Hello, everyone, and welcome to On Bordering, the final gathering of this year, Performing Borders Live 20. A program that I, Alessandro Cianetti, have curated with my brilliant friend and colleague, Xavier de Souza. Today, we are launching Lavander Men, Tonya Cori's performance to camera commission, and before starting, some housekeeping. The event is left optioned, and we want for this space to be an inclusive, accepting, welcoming, safe space for everyone, and any form of discrimination and hate speech will not be tolerated. If you need any support of any kind, please contact us in the comment section or at performingborders.gmail.com. The event is recorded and will be shared as a free to access resource on the Performing Borders Lada and our round websites. I also would like to thank our partners, the Levart Development Agency, Counterpoints Art, and HowRound The Other Commons for their amazing support for this launch and beyond, and they are Concealingland for funding the program. Lavander Men is an online conversation between two friends, Tonya Cori and Muhammad Ali Dali Agrabi, who have collaborated on three performances. Each performance happened in a different country and brought them closer. Their collaboration has changed their lives sometimes drastically and sometimes unintentionally. The screening will be followed by a conversation between Tonya Cori, Muhammad Ali Dali Agrabi, and Professor Harriet Hawkins and a Q&A with you all. Please write your comments and questions in the comments box and we'll pick them up from there. Tonya Cori is a live artist creating installations and performances focused on audience interactivity and concern with the ethical and political potential of such encounters. She is a distinguished artist in residence of theater and performance and director of the Center for Human Rights and the Arts at Barth College, New York. Her work has been presented in multiple languages across six continents. Muhammad Ali Dali Agrabi is a Tunisian theater artist and LGBT QI plus activist living in Malta. His latest creation, Would You Like to Dance with Me, was an interactive street performance with a group of asylum seekers. Dali worked on different campaigns with minority rights organizations in Tunisian Malta. He currently acts as a committee member of Malta LGBTQ rights movements. Harriet Hawkins is a professor in geography at the Royal Holloway University of London. Her research is focused on the advancement of the geo-humanities. I've filled the seats at the intersection of geographical scholarship with arts and humanities scholarship and practice. And now I leave you to Lavander Mann. Thank you. We're going to press a record on the sword. Sorry, it's taken me too long. I want to talk to you for a while, but you know, we've been working in Beirut for a while. How was Beirut? What happened? As I told you, we were lucky in Texas. We weren't injured. Our house was damaged. There were small things. You can see that it was damaged. We're fine. It was very big and traumatizing. It will stay with us for a very long time. At the age of 18, we're living a pandemic and economic collapse, one of the worst events in Lebanon. And the third biggest explosion in human history. I'll come visit you. Please come. I will train the dog. With your new mother. Yes. Habibi, finally. Yes. You've been there for two years? A little bit. Do you have a Maltese accent? I can hear right now. You lost your French accent in English. That's it. I lost my French, not only the accent. He speaks Maltese. Because he doesn't understand. Do you know a lot of people in Lebanon who don't know that Maltese is Arabic? They don't know Maltese. They have a strong resistance when you say that Maltese is Arabic. We don't know. We don't know in general. When you look at the picture from above, it's nice. When I'm happy, sometimes I say I regret asking for asylum. Because you can't go back to Tunisia? Yes. Do you work for a specific site? Do you work for a long time? Do you work for Tunisia? I'm asking for help. Your video is being edited. Your video is being edited. Sorry. Are you still editing? No. We are working with the community every day. We meet people in the city. We work very hard. We work for people. We are close to each other. We sleep and eat and dance. I don't know what to say. Do you still have them? I have them. The props we use here? The props. I have the sound system. I have the carpets. Aril. Oh, the boat drivers. Look at your boyfriend. I love watching it really fast. He's so pretty. He is. Did you love him in the show? Before the show or after the show? Everybody loved him in the show. Look how pretty he is. Before you loved him in the show? Before in the show and after the show. I got an assistant. She was a performer. I asked for help. She asked for help. I asked for help. She asked for help. She asked for help. She asked for help. She asked for help. I have an accent. I have a folder called Mania. Yes. I have a folder called Al-Akhra. Let me have a look. I love this place. I can see the performance. I can see the performance. Did you see me? This is your house. What happened to Lorenzo? Lorenzo is in Germany now. He is asking for help. It was like a moment that changed my life. They came to my workshop with the children of the neighborhood. They took me. I didn't understand anything. They didn't even let me walk.  They went to my house. Searched everything. They took everything. Humiliating kind of in front of the neighborhood. They are going like underground. Not knowing the time where you are and what you are doing here. Questions. For me it was super scary. I was always thinking about it. It changed my life also. It changed my life also. It changed my life also. So, yeah. Do you have pictures of the work that you did together in Lebanon? Do you remember this desk? You are sitting here. I am sitting here. Digitizing 5,000 meters. Look. All the letters here. All the letters from all over the world. The problem is the difference between the letters in London The delivery man came and called me and he gave it to me directly. Yes. But the one from Lebanon it was like a suspicious. Especially. Because we in the Arab world are not far from each other. This is our problem. That coming from London will be that we came to the police from Lebanon to get out. But she did an amazing job with it. Thank you. I wish you could see that installation. Look at how tired it is. He is tired. He is tired. He is tired of the police and the lights. I asked him to come. All the lights of the installation. I don't know. To be honest. That really in this folder this image that remind me always from the day that I gave it to and they put it on my Facebook and they saw everything. Yes. Because they asked for the password. They asked for the password. The password on Facebook, email, laptops, phone, everything. Yes. You know what they needed. They needed laptops as well. But the lawyer was much more... Yes, but they needed letters. Yes. Boxes of audience letter from Garden Speak. They asked what they needed. I put it in the installation. It was confiscated by the region police because they collaborated with us. They need to put it in the credit. Yes. Alexa? Alexa? Alexa? Alexa, come on. Alexa, what do you mean? Western Dream? No way. You help me read emails. You send me emails. Wow. You read the calendar. Do you remember me? Yes. Do you remember me now with the pasta? Wow. I remember everything. Radical activists, students, students, students, Alexa, music players. Why me? Why me? If you knew when you first started drinking lavender tea. These are the lavender that you brought me. I didn't know that lavender was a drink. Every time I drank it, I would remember all the spices and that's it. We got to know each other. But I also noticed that a young man came from a place that is conserved. From a certain place. He has nothing to do with art, politics, but he created a way for you and you have a lot of idealism in your work and in your society. And the issue is still not that this is the issue. But actually every time I asked why I decided to bring a baby. I wasn't sure that I would bring a baby. I think it's part of knowing about you and opening up to a feeling in general that I didn't have before. The feeling of being connected with people is not just about friendship.  You can also open up to a feeling that is very strange. And other things. I feel that I have been working with each other and I feel that I have also been connected with my own queerness. I don't. It's not like the coming out video. But I am listening to the music and I feel that I have to bring a baby. I want to bring a baby. I want to see the baby. I want to put the music. Listen to the music. Thank you for taking the time in the midst of all that's going on to produce such a heartfelt, sensitive and wonderful piece of work. I'm really excited and honoured to have the chance to develop the conversation with both of you tonight about this work. And of course with everyone who has joined us from around the world to enjoy the piece and also take part in the discussion. I promise not to monopolise it. I will be back in about 40-50 minutes and then there will be time for questions afterwards. Now in order to pose those questions if I can direct those of you listening to us and watching us to look to the top right of your screen right now you will see a little black-white outline of a speech bubble. If you click that it will open the chat window and in that chat window you will be able to type your questions. After we have had our conversation I will turn to address some of those. I have a good chance if I may to introduce our conversation by briefly reflecting on my own history with both of you. Not least because I think it will help the audience understand why exactly I'm here as a geographer. So as I said I'm a geographer and my work sits at the intersection of geographical themes of place, the environment, urban space and social justice. So when Tanya and I met many years ago now it felt like a really, really natural fit of sitting in a coffee shop in London having those kinds of really exciting exchanges that always seem to characterise that moment where you know you've met someone who you really hope to know for years and years to come. So Tanya has what I'm sure a number of you know now is over a decade of work at the intersection of live art, activism, social justice from her work with dictophone group including works such as The Sea is Mine exploring rights to space in Beirut to her work Garden Speak is lucky enough to get to a watch to evolve over a number of years. If you don't know this work Garden Speak creates an extraordinary powerful space in which as an audience members we get to listen to the oral histories of ten people killed at the beginning of the Syrian uprising and then buried in their gardens. I urge you to seek Garden Speak and Tanya's other work out on her website and of course eventually Garden Speak will hopefully start returring again and then you'll be able to see the extraordinary aspects of Garden Speak was the letters that Tanya invited you as an audience member to compose to the families and friends of those who have died as part of that installation and it's these letters which of course form the basis for the installation tell me what I can do and are of course integral to the evolution of Tanya and Dali's relationship and this piece that we've just seen. Now it was in the midst of some of the research I was doing to explore the very intricate relationships between the discipline of geography and artistic practice that I was lucky enough to travel to Tunis on Tanya's invitation to observe the evolution of the site specific piece Unmarry Us which Tanya was developing for the Dream City Festival there and it was in Tunis that I first met Dali who so profoundly shaped mine and I would go so far as to presume Tanya's experiences of Tunis the snaking streets passages and markets of the old Medina that he was kind enough to show us around but also the experiences of activism past and present in no street that he was kind enough and generous enough to share with us. What unfolded for me over the next week or so and for Tanya, Dali and the other collaborators was this incredible generosity of exchange and the most incredible experience for me of watching the final stages of a piece of live art develop. What emerged in front of me were the moving stories of intimate violence and the role of police and social relations in both enabling but crucially resisting this intimate violence but it was also a series of relationships that evolved, relationships between the women who are involved in telling the stories between the LGBTQ R.I. Plus activists in Tunis and of course as we'll hear between Tanya and Dali. What was clear from my slightly odd position as both an insider and an outsider to this work was this real sense of collaboration with the multiple forms that it took not least of course between the two of you Dali and Tanya. So to start our conversation I thought I'd ask you both to reflect if you can on your memories of unmarry us and your first memories of each other as a start point for the evolving of that friendship that has of course bought us to love and demand. Tanya can I invite you to respond? Thank you, thank you Harriet it's such a pleasure to actually be together. I know it's not as fun as being together in the midst of Madina and Tunis or in any room actually but it's good enough for me to be in a reunion together the three of us chatting and I want to also take this opportunity to thank Performing Borders and Bada for joining us together and giving me this chance to actually do a little reunion commission with Dali. Thinking about when we met in Tunis it was actually very very quick friendship that just happened very naturally together and people who work usually in performance and people who have studied theater know this feeling when you're in a studio together or in an rehearsal room and you just click on a different level, you click physically, you click mentally, energy wise this of course wasn't a theater or a studio it was the actual city but we very quickly I remember just walking in the street and just felt very natural that we are team together and on the same day we had dinner with a group of artists and one of the artists asked me if I brought my younger brother with me pointing at Dali and I said no he was my he's my artist assistant allocated by Dream Festival who put together an international artist with a local younger artist who would work as an artist assistant to help them put up the work in the city but it just stayed with me that it felt like we were family immediately Dali did you want to respond? to add on this, yes so to start thank you so much for this opportunity and everything like long time I didn't work with Danya it was like usual something like the idea very quick and perfect so yes when we first met I was thinking like because they told me the name of the artist so I was doing my research and looking and they was like oh she's famous what I would do with her yes I was thinking like this and then when I met her when she entered like she came from the airport it was like very natural hello and we started like kissing and we went I took like the luggage we went she rested a bit then we went for lunch and the conversation just started like that of all our life and everything without even knowing each other and even like a lot of other artists and artist assistants they were kind of jealous jealous yes a lot of them they asked like why are our assistants not like this and they was asking the same like because because it was feeling like it felt very very natural with Danya to be like this and to be part of the family even after you know I wonder if both of you can track through the importance of that idea of collaboration for your work obviously Unmarious was such a collaborative piece with you know so many different communities involved in that collaboration alongside the both of you but then also there was that wonderful moment in Lavender Man where you're like oh yes and the police they collaborated too and I thought that really kind of drew that richness of what collaboration could be out so I wondered if you could talk through how you maybe think through collaboration and maybe track us through how that happened in Unmarious so that kind of everyone can kind of know a bit more about that work that formed that relationship. Yeah so with side-specific work collaboration is key because often it's about looking at the politics of that space and when you're looking at the politics and history and design of a certain space you're looking at who uses that space do they feel welcome in that space do they feel abandoned by that space I wanted to in Unmarious to put on a wedding party on the rooftops of El Medina a wedding party that will involve activists from the LGBT community but also women from Bayti women's shelter and these women are often kind of hidden in the Medina because they're hiding from the abusers but also because of how the shelter is kind of hidden within the mazes or the streets of El Medina so I actually wanted to put these people out on the rooftops very clearly and tell them instead of them telling the story of abuse and of injustice actually working almost like geographers and urban researchers and tell us the story of Medina how it developed to be like that and by hearing that story we understand as audience that the design of El Medina and how the rooftops are linked with each other how the streets are so small that you feel safe in them you will make that link by yourself that actually this place that will look very harsh for our cider or will look quite conservative can act as a refuge for marginalized communities but it was very important for me that these people who might have been who are marginalized by the society abused by people to feel that their dignity is maintained in that work and that they have agency and how they present themselves so that's why collaborating with them is very important so it's not about just me directing them choreographing them in a way that they don't have a say or they don't bring what they have to the place but actually to work from their interest and their energy and their skills Dali can probably talk more about that but it's just everything developed from what we have around us so we just happened to have a friend who was always with us who was a cook so food became part of it Dali was supposed to be independent but because of who he is and where his house is and the stories that he tell he became part of the work himself so for me it's very important to collaborate in especially in such specific performances and to work with the team rather than force an already an already developed work and finished work on a team I want to add like I was really fascinated by the flexibility of Tanya with the work because it's not an artist that she came with an idea and she wanted to realize it there but the work started slowly slowly she started her research she started meeting people on different subjects from one and we have conversations after and we see what is happening in Dina itself and like even the presentation of the actual idea it was a surprise for me because the production team was always asking me to see the budget and everything what Tanya want to do and I'm like I don't know we still meeting people we don't know exactly what to do but like suddenly in the presentation of the idea she just start speaking about the wedding on the roof I start laughing on first I was thinking that she's joking but then I was like no she's serious and I started listening so yes this is the idea but it was like this and even with the community that we were working with it's a variable community and slowly slowly the work developed we had a text that we when we like when she saw that it's not needed anymore she just changed everything even the idea of the whole performance changed in the last 5 minutes and we did one rehearsal before we start the show so this kind of work it was very flexible for the women working in the performance and also for the story that she want to tell and to and she did this with all the work that we in every city Dali your your telling people's secrets I remember being really very profoundly impressed by I kind of arrived and I think you had kind of like 3 or 4 weeks to go before the performance and so it was sort of coming together but there were still lots of things that were really quite up in the air and it was really really fascinating to watch the way that the kind of all the different groups of people involved became such a central part of involving the way that the final piece kind of inhabited and explored that space and really working as you say Tanya with those skills but also Dali how it was so profoundly shaped by your skills and your knowledge too really intriguing to kind of watch and I'd also like to hear you talk through maybe how some of the things that you kind of saw happen and things that you kind of witnessed in those kinds in that collaboration and it's unfolding may have influenced the work that you've been doing in Malta because that that piece will you dance with me with the insight of silent seekers I'd really love to hear how that unfolded I thought you like I was so impressed by the work of Tanya and how she worked with communities and to start like would you like to dance with me it was an idea that just with who I want to work you know as now as a refugee coming from like I'm gay refugee so there is a specific kind of group and community that live here as LGBT migrants so there is certain kind of intersectionality between these two groups that they make people more vulnerable being not accepted from their own communities as being gays and not being accepted from the local communities for being migrants so this kind of idea brought me to why we don't interact with people and see it's a kind of experimentation what will happen there and then also taking in consideration that like some people were having some difficulties with the language and everything so we thought about recording all their story and kind of what they want to share and basically people they went in the street in Paletta in the capital city in front of the parliament and they are asking people to dance with them and people who accept will listen to a song from like a cultural song from that like someone's country and then they will hear a story and it will be a very intimate moment together through headphones linked to each other it's only them who hear all this also the idea of awkwardness being dancing with someone like a stranger in the street with no one hearing what you are hearing so it's kind of that kind of feeling also we worked on and it was in the same day it was they were like signing the petition to make 3rd of October as an international day for refugees so that was the work and they really built on what I learned from Tania because she always tell me working with the community is not easy even though you are part of the community and you have to understand and don't make your ideas as everything you always adapt and collaborate with others not it's like a kind of direction if I can throw that back to you Tania what do you think you have taken forward as broader lessons from the collaborative intersections we have the details of how the collaborations went forward into other works to discuss in more detail but those broader lessons of that collaboration it would be interesting to hear you reflect on that Tania I think that piece was very crucial to me unmarried because it was ideal in many ways the ideal situation for an artist who is interested in such specific performance is to work in a place that they love to be in with the community that they relate to with friends so obviously we started we didn't know each other but we ended up being friends so everything about that was an ideal situation and since then I have been trying to kind of find other ideal situation or try to think about any space and any group of people as this could be the beginning of a long-term relationship personal and professional I actually learn a lot obviously in the city because we ended up collaborating with a lot of his friends and his community and his friends changed how the work was going to be if he wasn't working with me but working with Dali because he's someone who has such a fresh take on everything he's still young he's starting his career and he's very he notices things and he makes links between various he has he's very attentive to details and because we've worked together a few times already so he kind of shows me how I work in a way that I'm not very aware of which is very nice for an artist so he always repeats that I work super fast which I knew about myself he's like you do things in five minutes you finish scenes in one minute you change everything on one day and I was like is that weird? I thought everybody worked like that that's why I kept telling him stop telling everybody it's exposing me so it's just I'm learning all of these things about myself and obviously about that space where we were together I've learned that from Dali Thank you I think it's precisely some of those textures and details of the collaborations and how they've evolved and the nature of that friendship that I found a really really powerful element of Lavender Man because a lot of my work has been trying to think through how collaborations and intersections of different bodies of knowledge and different forms of practice can happen sometimes it's geography and different forms of art sometimes it might be different kinds of communities and I think one of the things I found really striking about the account of collaboration that Lavender Man offers was that it kind of really draws out all the different kinds of aspects of collaboration it's both a kind of public thing because obviously you're making aspects of your collaboration public and some of the kinds of points where you both clearly had to confront quite difficult things that have emerged as a result of that collaboration but also things that have gone on to be very positive and collaboration in this context is both very public but also obviously so private and so intimate but also built through those really everyday little kinds of details and practices like the drinking of the Lavender Man tea which of course then becomes echoed in the title which I just think is a really lovely a really lovely kind of testament to that kind of daily ins and outsness of how relationships kind of form and also I think one of the things I was also really struck by when I was watching Lavender Man was a phrase I've been thinking about quite a lot recently by a theorist called Judith Butler who basically says kind of in relating we become undone and if we don't we miss something in a way that kind of relate and to care and to form relationships whether collaborative or not is about that kind of vulnerability and if we don't risk coming undone by each other we kind of miss something and I thought one of the things I think I was so struck by was the bravery of confronting some of the challenging aspects of collaboration that Lavender Man kind of draws out certainly for me as someone who kind of knows you both and I wondered if you could reflect on how it felt kind of exposing some of those kinds of difficult tricky questions about collaboration but also just the kind of intimacies of a relationship and the kinds of care and love that you feel for each other on screen because that was you know it was so powerful Dali do you want to go first when when Tanya first sent me the idea like her idea and what she wrote and she sent me an email and I was reading it I ended up crying and my boyfriend he was like no no no like what's happening and he read it and but because for me especially that long time now I didn't see Tanya like like we didn't met now for two years and it's a bit heavy to just kind of even the question that we asked it's not question that we asked ourselves before so it's everything new and we really discuss it at the first time there so it was something that it's heavy but in the same time I'm enjoying it because I'm with Tanya and I know that like sharing with her was always the thing we discuss everything and we don't have kind of limits and that's what I really love about our kind of relationship because it's really I call her mom she's not that old to be my mom but but that's the idea even like the way she asked me sometimes things to do and how to do it it's like it had to be strict so sometimes she's being the real mom and it's just actually as you said hi I think you describe it really powerfully that this particular project love and demand looking at our relationship looking at what we miss now in the live performance but live meeting but also looking at the ups and downs of collaboration and the very difficult moments and I felt that I was dealing with these quite shocking moments that we went through together Dali's arrest and me understanding that he was arrested because of the work that I've done and because our collaboration and realizing that it was actually by anti-terrorist police like so all over the word this is kind of the only police that you don't want to deal with because they function outside of the law and they could do whatever they basically could nap him so they could have just not given him back for as long as they wanted and so understanding the the responsibility and feeling that guilt related to my work and I always knew that working on the intersection between politics and live art and working with activists and working with contested events and contested spaces put people in danger but I was always hoping that it would be me that they would put in danger and I could deal with that because of the choice and I always thought that I found a way to maintain safety of people around me so that took me by surprise and and it really made me question whether the work is worth it whether collaboration is worth it and obviously it turned out and I had this conversation with Dali before like are you sure it turned out to be good for you are you sure you're okay are you sure and so I feel that this project is asking these questions they could be very very personal to us and very specific but I'm hoping that some of them are actually global and general to everyone who work together in collaboration now I think that question of our kind of ethical responsibility as collaborators towards each other is really I think very crucial not only to who we are as humans but then who we are especially if we sit in particular kinds of relationships whether it's an art making relationship or a research and art making relationship those questions of what makes an appropriate and ethical collaboration is vital especially when we're working I think as practitioners, as researchers and scholars with communities who in different contexts are kind of disempowered or marginalised in different kinds of ways and I think those ethical questions are very very complicated and very important to be asking ourselves I think I'd like to also pick up on something that's been a thread that's been running through both your answers to the last few sets of questions which has been that thread that I find so powerfully within all your work Tania anyway that really kind of powerful way that you bring to a certain kind of sensibility the intersections between the geopolitical and the intimate whether it's through kind of bodily intimate violences or whether it's through the kind of way we can track the questions of borders and how we engage with multiplicities of borders in a geopolitical context in an intimate context and obviously lavender man kind of brings those darly through your story and also through the kind of history of those collaborations and in particular that previous one called Malta and it strikes me that obviously one of the reasons we're here is to talk about performing borders and questions about kind of unbordering and what borders mean and you know I'm obviously one of those privileged people who's been relatively able to travel around the world pretty much as I wish for a number of for many years and I'm sure I'm not the only one who has found COVID-19 making us all consider our relationships with borders and our relationships with surveillance and obstruct kind of being obstructed at borders in ways that perhaps many of us have been of course incredibly privileged not to have to think about before obviously Brexit for those of us in Britain is raising those questions of borders in other kinds of ways too of course for many around the world borders are negotiating border restrictions and limits to movement and the violence that occurs there are sadly daily tragic tragic issues so I kind of would really like us to spend some time thinking through that question of borders for both of you those geopolitical borders the kind of questions around nation state and nationality but also how for you both it powerfully seems those intersect with other kinds of borders that may be bodily, they may be about the kind of cultures and societies we live in they may be boundaries around the world and how we love that kind of become intercepted very powerfully with those kinds of questions of the national border and the kind of geopolitical movement so I think there's many ways that come through in Lavender Man but I don't know if that's something that you'd be able to kind of comment reflect on Dali? How to start for me it was always a problem of borders that is the invisible and the visible borders that we are speaking about in Tunisia for example being part of the LGBT community is being like condemned with three years of prison it's like this criminal who is just walking in the street so you are waiting for your day kind of so you are in a kind of prison with borders but it's invisible for the moment and when I came here to Malta and I asked for asylum it's another procedure it's what the law says is something and what you live on everyday life it's another thing so waiting for example for my passport for two years and the half it was something like illegal from the side of the government it had to be in six months but everyday you ask and you don't know when and this is another border that you don't really see but you are waiting for something but you don't know when you will get it when you will get that kind of freedom of moving from a small really small island so borders can be really like you touch it, you feel it as now in Malta a small island with sea around or you can feel it in the way of everyday life how it goes being a Tunisian here and with this movement of like there is a big how to say it a big wave of hate speech seeing people quarantined in the sea in boats and they cannot enter the island seeing all this around it's very scary kind of seeing these borders it's going like they are building other kind of layers for these borders not only the passport not only the visas but more things to it and it's very scary on these moments now especially with the Covid it's like it's an argument now that they can use easily to stop people to make more borders to people I read somewhere that the official way that they measure global migration which is by the kind of granting of residence permits they've noted that in the first half of 2020 that fell by half and of course that's only kind of formal migration and we obviously know as you say very sadly that the kind of condition for migrants and refugees is so much worse under Covid-19 so yeah it's clearly a kind of issue that is drawing another lens on to kind of questions of global mobilities and immobilities Tania did you want to kind of respond to No I just want to say that I dream of a day when I don't work on borders anymore in a way I feel that maybe all of my work has been about borders in a way or another borders invisible intimate cities as borders the sea as border humans as borders and I just really hope that one day we don't focus on that anymore but it's not looking likely I think it's going to get worse now with rise of xenophobia around the world rise of right-wing politics again very populist but also with the economic collapse that been happening caused or made worse by the pandemic I think we're going to have another wave of closed borders lots of death on borders again and again and we're going to have to be forced to discuss the right to movement which seems like such an obvious and natural thing to do to be able to move to be able to expand horizons meet people and just because I feel that and I'm already nostalgic for it I felt like part of lavender man is to have this little almost being a little bit nostalgic to being able to meet people around the world and becoming friends with them and I feel that this now we can't do it right now because of the pandemic but I feel that it's going to become harder and harder with the cuts in the arts due to the pandemic with the inability to move sadly I feel that the words are going to get smaller and smaller and we're going to find ourselves already reminiscing to the times we were able to meet and become friends around the world I think it's really interesting you say that because when I was watching lavender man I was thinking similar things and I was also thinking about how I felt that one of the things that lavender man also posed provocatively for me in part of the way I think if I can describe it like this it seemed to use zoom as a medium if that's not a really horrible thing to say in terms of like you know zoom as a medium seems like yeah but I just felt that one of the things I kind of found fascinating was there was a geographer historian years ago called Francis Fukuyama who talked about the end of history and the end of geography and that globalization meant we no longer had to kind of ask some of these questions about nation state based borders and boundaries because everything was becoming so connected and that the internet has been kind of prophesized as another kind of tool of this kind of end of geography and I think I was very struck when I was watching lavender man about the way that there sort of seemed to be a kind of mobilization of a number of kind of tools that could make us think of zoom as a sort of the site of zoom I guess as the kind of iteration of site-specific work for a pandemic times where the way that you used the gestures of movement on the screen where you mirrored each other or copied each other was so powerful especially because the first time I watched the piece I didn't have the translation and I don't speak Arabic so I was not able to understand a lot of what you said apart from the kind of points where you broke into English or occasionally French and then I could kind of pick things up but that made me really focus on the gestures and it made me really really conscious of the kind of infrastructures of zoom as a kind of site in which to make work and the way that the menus kind of came up and gave a glimpse into your computer darling with your folder called Tanya and so I wondered if you could kind of reflect on kind of what it was like to make a piece of performance work when both of you are used to working with kind of live communities that use the internet in this way and that use kind of zoom as a tool and how that felt like and if you even thought about it in that way or if I'm kind of projecting my geographical interest in the sites of the kind of production and consumption of work onto your piece here Thank you for that I actually made me realise that I worked with zoom as a site without really being aware of it without really thinking that this is a site specific piece but it was a decision to work on zoom because of how we used it to check with each other about how to use it with work and just like a site how it affects how you relate to others or other performers and how you perform the work I felt that zoom actually indicated or led us to how we connected with each other for example the fact that it has these white boards so you could draw on it and becomes a reveal oh is he gonna ask me the fact that I've noticed in zoom that people kind of I personally noticed where people are looking and how they they move their body so this affected that exercise that we tried together oh so let's kind of like move differently or try to mirror or not mirror each other and different things that we tested even with the virtual background that we don't end up using we've also used captions so it was actually like a site and a site that we recently discovered because of the pandemic I mean I've used it before but it was never like such part of my daily life so yeah I think you're absolutely right that it was a site that just like any site it indicated how we work together and it affected the work I was also very struck by the ways that things that we're probably all so familiar with now from zoom and teams or google hangouts or whatever the kind of the way the domestic kind of comes into spaces it might not normally come into and the kind of are we on yet are you muted are you not muted and the kind of breaking down of the internet becomes kind of part of the conditions of how we kind of understand the work I wonder what your thoughts were because I was I think obviously Tanya makes it clear but I was also very struck by that kind of Alexa moment as well which speaks to another kind of element of those technologies and the kind of normalcy of everyday life kind of coming in in a particular way yes like I believe that the pandemic put us in a situation where we have to explore with like all the technology around us as artists because like to be honest the sexuality between different different elements of the art the media the like editing a video and these kind of things usually we don't think about it when you are we are working in live art and theater and music or and different things but now in this pandemic we are stuck at home and we need something to work and really like we need art to kind of really our existence as artists so working with these technologies always there is constraints within but there is also a lot of things to do and to create and really like after when Tanya was sending me the drafts of the videos and of the film and seeing the change and the editing part and everything it was amazing for me it's a piece of art on itself it's like a work of art on itself seeing the changing between like the first material and what came to it and what art to it and this animation and things it's very interesting well thank you very much both of you for the conversation I think I'm now going to with our last kind of 20 minutes or so take the opportunity to avail ourselves of another kind of form of the technology which is to take questions from audience in a kind of disembodied way so thank you very much for those of you who've been putting your questions in the chat for those of you who haven't had a chance if I can remind you it should be a little white outline of a speech bubble in the top right of your viewing screen if you click that you'll open a chat bar and in that you can post some questions and I should confess that the performing borders team have fantastically set up a system whereby I have questions on a separate document so I'm now going to definitely perform the sideways zoom eyes to look at my other document in order to read out some of these questions and pose them to you so I'm going to start with one from Florence which is to both of you and it's a question that I was really also wanting to post to you so it's really great she asks do you think the pandemic has shown us how arbitrary and blurred borders are and how we're never in our own universal space and that what we do always affect someone else and I guess linked to that as well I'd be interested if you can reflect on how the pandemic has kind of asked us to think about the sustainability of our actions as kind of artists and practitioners yeah I'm trying to repeat the first part of the question to myself you want me to repeat it okay so do you think the pandemic has shown us how arbitrary and blurred borders are and how we're never in our own universal space and how what we do always affect someone hmm yeah I think that we already knew that but the pandemic just made it like everything you know the pandemic just made things much bigger so here in Lebanon for example we've had so many difficult difficulties like total economic collapse political corruption and the pandemic made it worse and I think our relationship to borders the pandemic is just kind of putting a huge magnifier the precarity of work especially of art workers again the pandemic has made it much worse so I think this is what's been happening recently if I understood the question right yeah no I think so also from my perspective I don't know about you both but I've also become really aware of my body in a really extended way so all those kinds of discussions of what happens when you sneeze and you're shedding virus and are you shedding virus and the kind of sense that one may be contagious that breaks down the kind of boundaries of your relationship to kind of other people in different kinds of ways and those awkward pavement dances that have become a kind of a factor of life where everyone's like which way is everyone going? Dali I don't know how's it been in Malta? Malta is like the same as in the rest of the world but thinking about Malta as a really small country it's like everything is accentuated like we feel it more because like maximum we will go 20 km and we are in the end of the island so it's not like there is nothing to do even in your own country so travelling was an issue when everything stopped and everything and really people they start thinking of if now I cannot just travel to Sicily so people who were stuck for all their lives in their countries how they are feeling and how their thoughts go about borders and about all these kind of things also at a certain point we were stuck at home so it's another border going out in the street it was something that we couldn't do it's a kind of the pandemic helped this but at the same time it spread this kind of this hate speech of fear of the other and as you said we start being afraid of anyone who sneezes or cough in the street and thinking about even people who are coming to the country and this stigma on everyone who travel that he's carrying the virus and he's spreading it to other places and every time it's about the foreigners who are bringing the virus to us and like send them back to their countries or don't let them in so this is the idea it's becoming stronger also from both ways great thank you I've got a question here from Kate particularly Tanya a lot of your work Kate says revolves around international collaboration do you feel that the pandemic has stifled that or opened it up further with performance moving into digital spaces I haven't collaborated with anyone yet who I haven't collaborated with already so I think because I've felt that I mainly missed my friends all over the world when I had the chance to do digital pieces I've collaborated with Basel many of you know him Basel Zadaa who I worked with on as far as my fingertips take me so I collaborated with him again and I collaborated with Dali again I just felt like I needed to preserve these connections that I had because I miss my friends that I miss that part of my life and these conversations that I already started I think if we stay much longer in this situation perhaps it will allow me to collaborate with people that perhaps I can't I can't meet around the world for various reasons for example as 11 years I'm not allowed to go into occupied Palestine for example I could do a digital piece with people there for example just giving you an example but I haven't gotten to it yet yeah no I think there's possibilities but also as you say using the kind of opportunity to also use the digital spaces to reform connections that already exist in different kinds of ways Dali there's a question here for you from Marianne who's asking can you talk about the areas of difference between working as an artist in exile and then work within home communities working in like at home you feel you know everything kind of so you know where to go and who to ask and these kind of things there is no difficulties in your resources and in your research that you can do working here it's very different because you cannot work without knowing people without getting to have a community in the beginning without getting to know how things go so you start from the beginning you start everything and now I'm having a BA in Performing Arts so I'm even like helping to know and to know people in the industry and to know people around me so that's the difference mainly between working here and there great thank you Bobby has a question for both of you he says this is a great global conversation building on what you're saying about the pandemic I'm wondering if you're finding new opportunities for global solidarity with other artists and communities Tanya you've already kind of nodded towards how that might work for you Dali do you think that's something that you've been able to take advantage of yet or Tanya is there anything else you'd like to add on that I just I just think that now we have a chance we have an opportunity in the art world to think about how if we can reimagine our industry our work culture and if we start from solidarity with each other I think it's very important we are at the moment now when government are asking us to prove our worth to society and this is a very dangerous situation to be in because let them try to be without art all their life and then come back to us so I feel if we start at least in solidarity and understand that the most precarious people amongst us are the ones that usually are made redundant first are put on the side first people especially a workers art workers of color we've seen venues around the world balance their budgets on the back of these people and we should just resist that and we should be in solidarity with each other and understand how we could reimagine all together a post-pandemic work that is built on more equal and fair work ethics Dali was there anything you wanted to add or because I've got another question here about the local scene in Malta to ask if that so I'll move it from the global to the local so Juliane asks being a multi artist who lives abroad I look at the art I've seen in Malta and feel like it can sometimes feel restricted what's been your experience and take on the local scene and the funding that you found there and how to say it but like the local scene in Malta it's very limited yes but also it's we say it's a green space so you can work on it and you can involve something and can experiment Malta like have too many beautiful places and sites and things that you can work on usually the work what's done here it's like the classic theater the dance opera these kind of like pentamime and these kind of things but like now new movements of like young artists that they are working on site specific performances or on live performances interactive with audience and things and this is I think what I saw here after Valetta 2018 I saw that it's a new thing that start in Malta and it's always it gives you time to experiment yourself and to see and also to collaborate with others outside of Malta that's really exciting to hear about that kind of that green space as such a kind of yeah really interesting to see so Dale has a question which I think is a really nice one as we start to kind of wind into our final kind of 10 minutes he asks I've been an artist just starting my career and I'm often overwhelmed knowing where to start can you both please share some advice on what happened and what helped you when you first began creating art and performance so top tips would be would be welcome I like when people ask this question because obviously it's very different for everybody there is no rules but always helps to hear other people what works for them what works for me is to always find your people wherever you are like find people that you can trust that you can collaborate with and try to think that you are part of a community but also part of a click like people who would support each other with watch each other's work help each other and it's very important because you can't do it alone whatever medium it is you can't do it alone and then when you're actually working together you end up setting a culture by yourself a culture that people want to be part of a movement of sort and another tip would be that not to compromise on what's very important so draw the line on what's important for you if these are the ethics and the politics of the work then you draw the line there you could be flexible in everything else in where the work would go flexible in how the outcome there are places that you should be super flexible in because it's better for the work and better for you as human and as an artist and it will make you grow but there are specific things that you need to find that you should draw the line in and do not compromise no matter what happens and people don't be scared to do that because people will respect that Dali, top tips I think Danya said everything and I am myself starting my career and to be honest I answered this question before when I said when I moved here the first thing that I did is to know people to have a community and that's what Danya said so yes particularly it's very important because like they put you in connection this is one but they help you in developing a lot of things a lot of skills ideas like language we use in the art scene and everything so this is help you become knowing and become like shape your work and shape ideas thank you I think that is actually sadly but wonderfully a really wonderful place to end to bring kind of background to that question of relations and collaborations I guess the kind of centrality of people and those relationships which is obviously so so crucial to both of your work but also in particular comes so much and so strongly to the four in Lavender Man we leave the live stream and also the live captioner at 8 o'clock and I think it's important that there's some time for some thank yous so I think I would like to thank you all well thank sorry thank on all your behalf Alessandro Xavier and the team at performing borders for their support and both of the collaboration that we've seen in the new commission but also obviously of kind of making this event this evening happen I'd also like to thank Julia who I'm sure my rapid speech has not the easiest of live captioning so thank you to everyone who's been working behind the scenes to put this event on obviously thank you all for you as an audience and to everybody who posed questions I'm sorry that we couldn't kind of dwell on some of them for longer but that's unfortunately kind of the way with these I'm sure that if you email Tanya and Dali they will be happy to kind of open up discussion and make other connections and finally of course I want to thank Tanya and Dali for sharing both Lavender Man with us but also for the inspiring and incredibly generous conversation collaborations are of course incredibly public things and we enjoy consuming the results but there are also intensely private relationships that touch us all incredibly deeply and can also have very challenging private moments I'm doing us of course in this process and I want to thank Dali and Tanya personally but also in your behalf for sharing their collaboration with us and for doing so so generously and openly and so thank you all very much everybody have a wonderful rest of your day wherever you are in the world whether you're about to go to bed or whether your afternoon is just starting or wherever so thank you very much good to talk to you and thank you for sharing all of that with us and Dali thank you thank you Harriet thank you Tanya also


Hello, this is the next session of this course or I should say the segment 3 of the course on nano-electronic device fabrication and characterization. In the previous session, we learned about the nucleation and growth of nano particles in a homogeneous medium such as a liquid. And then we went on to consider the growth of nanocrystals of metals of semiconductors leading to the formation of quantum dots specifically of cadmium selenide. And then we discussed the growth of nanowires through the vapor liquid solid or the VLS method. What we shall do is to continue to discuss the growth of nanocrystals and also of nanowires to touch upon certain aspects that are important because what we described last time especially regarding nanocrystals growth was really the protocols for doing so. I mentioned in a part of the, I mentioned last time that crystals of metals, nanocrystals of metals especially platinum which I gave an example of was affected by the presence of polymers such as sodium polyacrylate which gave us specific shapes depending on the extent of the polymer present in the solution from which nanocrystals of metals in particular that of platinum are grown. Now, these are known as polymer stabilizers and are very useful for the growth of I should say cut the controlled growth of nanocrystals in general and specifically the nanocrystals of metals and semiconductors. There are a number of such polymer stabilizers polyethylene imine, polyvinyl pyrrolidone, sodium polyacrylate and so on. These are introduced primarily into the growth solution to form a monolayer on the nano particle or the crystal that is incipient that is growing. So, it forms a monolayer on the surface of this growing nanoparticle and the purpose of that is to prevent agglomeration that is we do not want these nanocrystals that are formed to agglomerate into entities that are really not individual crystals, but they are really combinations of nanocrystals that are essentially sticking together. So, if one wants to have nanocrystals that are separate from one another that do not become agglomerates aggregates then the use of such polymer stabilizers which form a thin layer on the surface of the growing nanoparticle is really very useful indeed essential. Now, it also turns out that these stabilizers can be used and can have various other influences depending on the surface chemistry of the solid, the polymer under solvent together as well as the temperature. The presence of such polymer stabilizers can for example, prevent the diffusion of growth species from the solution to the growing particle that is while we wish to prevent agglomeration it can also have the effect of preventing growth of the nanoparticle which may which we may desire to a certain controlled extent. The presence of the polymer stabilizers can also lead to the growth of preferred crystallographic planes that is to the faster growth of certain planes and the relatively slower growth of some other planes which can lead to shaped nanocrystals. This is what we saw in the growth of platinum nanoparticles in a solution that contained platinic acid H2 PTCL6 and sodium polyacrylates in different proportions. For example, on the left is a solution where the proportion of the two that is the platinic acid and the polymer stabilizer is one to one and in the second case on the right are images of nanoparticles of platinum formed when the sodium polyacrylate is in a much greater proportion that is the proportion is one is to five. So, what this illustrates is that one can actually control the shapes of nanocrystals that are formed using polymer stabilizers or polymer additives to the growing solution from which the crystals are grown in a controlled fashion, in a controlled proportion and also of course very often the temperature at which these reactions are conducted that form the nanocrystals through reduction the temperature is also an important factor. What is also an important factor as already mentioned is the solution from which this is grown that is you have H2 PTCL6 as well as sodium polyacrylate these are solutes in a solvent. So, what is the solvent one uses? So, these are all factors that can influence the emergence of nanoparticles of different shapes and different sizes controlled shapes and controlled sizes. Now, we have referred to the synthesis of cadmium nanocrystals cadmium selenide nanoprocesses last time through protocols that prepare the selenium precursors precursor I should say through the addition of octadecine, triactyl phosphine and then the preparation of the cadmium precursor which is the cadmium oxide and then an oleic acid solution is prepared again with octadecine and so on. So, these are subsequently mixed together and as I mentioned last time at an elevated temperature these are made to react so as to form cadmium selenide and particles of different sizes are separated by altering the reaction times that is to take out the solution at intervals of 10 seconds for example, each of those samples taken out at fixed intervals gives us cadmium selenide crystals of a certain size and of course, the size increases as the reaction time increases. Now, what is important to mention in the growth of semiconductor nanocrystals? What is important to understand is that the growth of these nanocrystals which are really compound semiconductors occurs commonly through the pyrolysis of organometallic precursors as we have seen here and unhydrous solvents. What is very important is that there is no hydration and also that there should be an inert ambient for these things. So, usually these are done in organ atmosphere or very dry nitrogen atmosphere or in a glove box so that there is no possibility of oxygen in trace quantities being present neither should there be any moisture and a polymer stabilizer or a capping material so called capping material. In this case we have octadecine for example, so they need not be polymers for example, it is often called a capping material what a capping material does is to literally cap to the growth of the nanocrystals to a certain degree or after a certain extent of growth. What is involved in the preparation of compound semiconductor nanocrystals which are really quantum dots as we discussed earlier is that there should be nucleation of the nanocrystals of the compound semiconductor through rapid injection of reactants to attain super saturation that is you inject them as we have shown last time it is rapidly injected into the solution from which growth takes place and by the rapid injection super saturation is induced. And then the phenomenon that is known as Oswald ripening is at play during the growth and what Oswald ripening really means is that as the growth takes place there is a distribution of sizes of these crystals that naturally occurs because some crystals grow larger at the expense of others. So, a certain degree of this growth that is these sizes then ripen Oswald ripening is the growth of crystals at the expense of smaller ones growth of larger crystals at the expense of smaller ones. Now, because of such growth that is the larger crystals essentially eating up the smaller ones what it does is to reduce these distribution of sizes that is it tends it leads us towards mono dispersity. So, Oswald ripening is a friend in the preparation of quantum dots that are mono dispersed. So, Oswald ripening is therefore, exploited to obtain mono dispersed crystals of compound semiconductors and size selective precipitation is done as pointed out earlier in the protocol whereby we take out certain amounts of the solution of the growth medium. So, that at different intervals we separate out crystals that are of different sizes. So, that is size selective precipitation to obtain mono dispersity which is which is aided by the phenomenon of Oswald ripening. The termination of growth for example, you know we do not necessarily want growth to go on indefinitely we want to limit it and that can be achieved when the organic components are occupy the surface of the growth sites or covered by that is the growth surfaces is covered by an organic entity and the presence of such an organic entity has shown in this cartoon can then prevent additional growth. For example, something like this can be injected into the growth solution after the growth has proceeded for a certain interval. So, one can therefore, achieve the termination of growth at a desired stage. Now, so far we have dealt with metal nanoparticles, nanocrystals I should say all these are nanocrystals, metal nanocrystals, compound semiconductor nanocrystals and earlier we have dealt with nanocrystals in one dimension namely nanowires of semiconductors such as silicon. Many semiconductors are actually oxides often complex oxides and oxides are actually oxides and oxide nanoparticles nanocrystals of oxides are potentially very important they have significant applications for example, as catalysts. So, the growth of oxide nanocrystals is also worth looking into, but the method of growth for oxide nanocrystals is significantly different from the method of growth for either metals or compound semiconductors and a process known as sol-gel processing is often employed among other methods. So, this sol-gel processing is the synthesis of colloidal involves synthesis of colloidal dispersions of inorganic and organic hybrids. So, one can obtain inorganic materials like oxides, one can also obtain nanocrystals or nanomaterials of inorganic organic hybrids through such a process and through this process one can also obtain fibers, powders, thin films and so on. So, it is a versatile method for the preparation of oxide primarily oxide materials or hybrids that contain oxides. As I said it is also an excellent way of making complex oxides such as perovskites such as ferrites and so forth. Perovskites are A B O 3 oxides ferrites are A B 2 O 4 oxides and so forth and these have significant applications. For example, B A T I O 3 perovskite is a very important p H O electric material. Sol-gel processing involves chemical precursors which are usually alkoxides or inorganic and organic salts and it involves organic or aqueous solvents which may be used often with catalyst added to the solution to get the process going at a desired rate. The sol-gel process contains two steps, two aspects so called hydrolysis and condensation. So, in the example shown we have a metal ethoxide O E T 4 is a E T stands for the ethyl groups E 2 H 5. So, we have a metal ethoxide which is one of the alkoxides, alkoxides are very fond of moisture. So, they quickly take up water or moisture and form the kind of the there is hydrolysis and formation of a complex as the as is shown here where some of the water is taken up by the ethyl group and then there is condensation. So, this moiety over here that is shown this moiety takes up hydroxyl moieties and we have eventually the formation of this complex entity due to condensation. Both of these steps hydrolysis and condensation are multiple step processes pretty complex processes and they may occur sequentially they may occur simultaneously depending on how exactly the process is designed. This condensation step that is shown here results in the formation of nanoscare clusters of metal oxides and hydroxides as you can see here. This is an entity and depending on the aging of this how long one carries out this process one can obtain through this a metal oxide or a hydroxide often with an organic group attached to it and so on. So, this is the result of the condensation process which is then subsequently heat treated to obtain the desired oxide material oxide structures. So, following condensation the product is fired which means that heat treated to a modest temperature modest by the standards of oxides oxides often require high temperatures of formation, but the solial process reduces the temperatures that are required to obtain oxides and oxide nanostructures to a significant degree and it also allows us to obtain as a result fine structured crystalline oxides nanostructured crystalline oxides. For example, barium titanate B A T I O 3 which I just mentioned a moment ago is obtained at a relatively low temperature of 400 to 700 degrees whereas by a different process usually the so called solid state reaction process the temperatures required for obtaining barium titanate is more than 1000 degrees. So, a significant reduction in temperature is achieved by the use of solial processing and precisely because much lower temperatures are used it is possible it becomes possible to obtain much smaller size crystals or nano crystals. Size control of these particles is possible through the variation of concentration of the reactants and by controlling the so called aging time how long one lets the sol-gel process proceed. So, it is possible through such controls to obtain mono disperse oxide particles in the range of 1 to 100 nanometers in size. A number of oxides can be prepared really there is no essential restriction on what kind of oxides can be prepared usually some kind of a metal complex or an alkoxide is possible for almost any useful metal. Now, one important aspect that we should keep in mind over here which I think I probably did not mention earlier is that a way to restrict the size of crystals that is to limit them to the nanometric regime is to have processes design processes conduct processes of growth at a low temperature that is simply the K T so called K T factor for crystals to grow the species that are involved in the growth have to have sufficient energy to move about and therefore, to have the energy to assemble together to become larger pieces larger crystals. Therefore, when a when the temperature is low this energy is low and therefore, first of all the process is slow and secondly, because of the limited mobility of the growth species the growth rate is low and therefore, becomes controllable and often one can have very excellent control over the growth rates by controlling the temperature at which these reactions are conducted and by limiting the temperature at which these reactions are conducted. Another thing that one could remember one could one could note in this context is that one way to prevent crystallization essentially obviate crystallization is to go from a high temperature to a low temperature very rapidly that is through quenching temperature quenching. So, if you had a melt for example, and therefore, you could take the melt from a relatively high temperature which is melting point to room temperature very rapidly by quenching then the kinetics of the process do not allow for crystallization to take place and one could end up with amorphous material because no time is allowed for the relaxation of these growth species into equilibrium positions which they would occupy in their crystalline state. So, not only can one obtain nano materials through this kind of rapid cooling controlled rapid cooling one can all together prevent crystallization from taking place to obtain amorphous materials even metals which tend to crystallize very readily can be obtained in amorphous form through this quenching process. It is also important to remember that not only can you have nano crystals, nano rods, nano wires and so forth, but one can also have bulk materials that are nano structured. I just mentioned amorphous and glassy materials I just mentioned amorphous materials through quenching and one of these things is through quenching a melt from high temperature you would get amorphous or glassy material and that is nano structured often all together non crystalline. So, that is an example of bulk materials which are very finely structured nano structured if it is crystalline one can have nano porous materials that is bulk materials with substantial macroscopic dimensions but with porosity on a nanometer scale. So, these are for example, the zeolite materials I do not know whether we will have time to actually go through zeolites as a class of materials, but zeolites which are very important as catalyst materials or these porous materials mesoporous for example, a micro porous. So, that they have very large pores inside which act as sites for catalytic reaction promoting catalytic reaction. Multi layer thin films which we mentioned in passing at least last time where we discussed processes like molecular beam epitaxy and MOCVD. So, that one can get multiple layers multiple quantum wells or super lattices and so forth even though individual layers there would be nanometric in range you can have a stack of layers that together is substantial apart from having a relatively large area for each layer only the layer thickness is small. So, that would be a nano structured bulk material and such materials would behave like bulk materials. For example, the band gap of gallium arsenide that is 3 nanometers thick or 10 nanometers thick that is grown by an epitaxial method is the same as the band gap of bulk gallium arsenide crystals because the way it is grown it is not a nanoparticle, but a nanometric single crystalline layer therefore, its behavior is that of a macroscopic gallium arsenide crystal, but we form quantum wells by alternately layering or sandwiching a gallium arsenide layer between gallium aluminum arsenide on either side layers of gallium aluminum arsenide on either side. So, all these are examples of nano structured bulk material. Now, such nano structured bulk material would for example, comprise nano crystals that are compacted together. You can have nano composites where for example, you have individual components in the composite each of which is nano structured, but then put together often through a process such as you know pressing them together and so on that results in a nano structured bulk material it could be an alloy for example. So, in this case the nano structuring of the material even though it is bulk the nano structuring affects its chemical physical mechanical properties and often these properties are enhanced if the individual components or if the parts of the nano structured bulk material or the constituents are nano structured. You have bulk material of which the constituents are nano structured and as a result of it you have enhancement of certain properties depending on the nature of the components nature of the constituents of such nano structured bulk material. So, it is important to remember that we do not necessarily mean only quantum dots or nanowires and so forth when we talk about nano materials nano structured bulk materials or an important aspect of nano materials. Examples here you know for example, an important aspect of nano structure bulk material or the so called thermal barrier coatings where you have nano structured material as shown in this micro graph of yttrium stabilized zirconia over here where you can see nano crystals regions of crystalline zirconia and such materials are so called thermal barrier coatings which are able to withstand or which are able to support large thermal gradients for example, in the exhaust of a jet engine. Other applications include catalysts as already mentioned solar cells batteries and so forth. So, all these are examples of applications of nano structured bulk material. Next time we mentioned homogeneous nucleation where we studied how nucleation is a result of the balance of energies, how the Gibbs free energy and the components of the Gibbs free energy then drive the formation of nuclei within the homogeneous medium. So, in heterogeneous nucleation what you have is nucleation taking place for example, from the liquid phase on to a solid surface or from the gas phase on to a solid surface. So, this is heterogeneous nucleation in the context of nano materials. Now, what is shown here is a graph is a is a is a figure that sketches the formation of a nucleus on a flat surface that is shown here. So, you have a solid surface and a nucleus is formed over here that has this kind of a shape approximately a part of a sphere. In such a nucleation process then various energies surface energies, surface energies per unit area at the different interfaces that are present play a role. Theta is the contact angle of this nucleus theta is shown here that is the contact angle and the different energies are gamma s v gamma s f and gamma v f. These are the respective energy per unit area at the substrate vapor because we are nucleating from the vapor on a solid substrate. So, gamma s v represents the substrate vapor interfacial energy and then you have the substrate nucleus interfacial energy over here because the nucleus is forming on the substrate and then you also have the vapor nucleus interface. So, you have three interfacial energies that are involved in the formation of this nucleus due to a heterogeneous process. If theta is 0 if sorry let us begin with theta being 180 degrees that is this theta is 180 degrees 180 degrees. So, then what you have really you would have a sphere you would have a sphere a droplet sitting on the surface not wetting the surface at all. So, no nucleation has taken place because really then you have nothing that is attached or bound to the substrate surface or the growth surface. Whereas, when theta equals 0 that is this one this nucleus is making a 0 contact angle with the substrate surface then you really have complete wetting of the substrate surface by the nucleus that is formed from the heterogeneous medium. This for example would be the case of homogeneous epitaxy or homo epitaxy where for example gallium arsenide can grow on a crystal of gallium arsenide as simply an extension of the crystal that is suppose I have a nucleus of gallium arsenide and the substrate is gallium arsenide. Let us say the substrate is a single crystal of gallium arsenide. So, this nucleus then becomes simply an extension of the crystal that is underneath that is called epitaxial growth on top of epitaxial means on top of. So, this growth of gallium arsenide on gallium arsenide. So, it is one and the same material. So, that is the case where the contact angle is 0. So, let us say sort of a simple case of heterogeneous nucleation, but a very important part of it I mentioned this last time MOCVD metal organic chemical vapor deposition more accurately called OMVPE that is organometallic vapor phase epitaxy that is a process whereby one grows a material like gallium arsenide or gallium aluminum arsenide on gallium arsenide itself. So, one grows a thin layer of gallium aluminum arsenide on gallium arsenide and that becomes possible because the lattice constant of gallium arsenide is substantially the same as the lattice constant of gallium aluminum arsenide. So, it is a case of homoepitaxy and in that case the vapor contains the species that are responsible for gallium arsenide on gallium arsenide. So, one brings in a species in this particular case a compound called trimethyl gallium that is. So, you have trimethyl gallium and the vapor also brings in another component arsene. So, this is the arsene gas. So, this is trimethyl gallium. So, these two combine together on the substrate surface to give us gallium arsenide and they liberate methane which is a gas and escapes from the surface. So, this is heterogeneous nucleation of gallium arsenide on gallium arsenide and as I said in such a case there is zero contact angle and very easy growth of the film on the substrate. Now, again as in the case of homogenous nucleation one has to take account of the different components of the Gibbs free energy which are listed here the different surface energies or being the radius or being the radius of this nucleus average radius of this nucleus and delta mu v is the change in the Gibbs free energy per unit volume as a result of this nucleation and the different components of this interfacial energy I have just described. So, one sets up this delta G and of course delta G has to be negative in order for nucleation to take place spontaneously. Now, one can show through a detailed analysis that is why for example here in this diagram we have shown the contact angle and the different components and so forth by using this diagram one can write down the different terms over here in terms of the r and the cosine theta and so forth and one can arrive as a result of this analysis that if this gamma S v is less than the sum of the other two interfacial energies then in that case so called island type growth takes place that is one gets islands of that is we get crystalline crystal material formation due to nucleation on the surface that is one would get islands over here for example one would get crystals forming on the surface of the crystal of the substrate and these would be nano crystals that is you now have nucleation of the nucleation on the substrate of the material of which for example you may want quantum dots that is you want to grow nano crystals due to heterogeneous nucleation on the surface and that is what happens when this condition is satisfied. So, one gets island type growth and there is a name for it attached to two scientists is called the Wollmer Weber growth mode which is important in the context of thin film growth we shall come to that I think in the next session. So, heterogeneous nucleation therefore leads to the formation under these conditions of quantum dots on this surface due to nucleation from for example the vapor phase. Now, the context in which this becomes relevant is the so called evaporation condensation process that is you have a substrate or the solid surface on which you want to have nucleation to take place either to give you quantum dots or nano crystals or to give a give you a continuous film which may comprise come quantum dots or which may really be an epitaxial surface of a very small thickness as we mentioned earlier. So, in this evaporation condensation process clearly you have a heterogeneous growth process taking place you have evaporation separated think of evaporating some material and then collecting them or condensing them on a substrate surface that process as shown in this cartoon is a multi step process in the bulk of the vapor let us consider this vapor. So, in the vapor phase you have to create the growth species that you are interested in collecting on the substrate in a crystalline form. Now, these have to diffuse from the bulk diffuse on the bulk on to the substrate surface of the growth surface where you want to have this heterogeneous growth taking place nucleation and growth taking place. So, they have to diffuse on the bulk of the vapor on to the surface and then they have to get adsorbed on to the surface they may get desorbed also you know without really having much of a dwell time on the substrate surface usually the substrate surface is at some elevated temperature not necessarily at a low temperature. So, usually this lands on a substrate that is reasonably at an elevated temperature therefore adsorption is not guaranteed there can be enough energy for this growth species to just get ejected out of the growth surface because the growth surface is hot and those species that get adsorbed on the surface can have mobility on along the surface surface diffusion of the growth species remember we are interested in the growth of crystals on this surface from the vapor phase. So, there is diffusion along the surface of the substrate and then when this takes place that is when you have the chance of nucleation of a crystal and the growth of a crystal what you want to have is irreversible incorporation of the growth species into a crystal structure to begin with of course, a nano structure a nano crystal and this one as we just now described in the case of gallium arsenide you actually have a chemical reaction taking place and if that is the case then you have the desorption of reaction byproducts such as for example, methane as I showed you just a moment ago. So, you have the desorption of the reaction byproducts and then of course, really these byproducts such as methane that is in the vapor phase would get diffused out of this chamber this vicinity. So, this process has to continue where there is diffusion of the growth species on to the surface it gets adsorbed on the surface is mobile on the surface due to diffusion gets incorporated into crystals and so on. So, this process has to continue for the growth of a crystal for the nucleation to occur and for the nucleation to lead to growth. So, there are multiple steps this is a pretty complicated process actually of these six steps that are shown here it turns out that the most likely rate limiting steps that is the ones that control the rate of growth of the nano crystal on the surface the ones that control the growth or the rate limiting step or the step number two namely the adsorption of the growth species on to the growth surface and then the incorporation of these growth species into a growing crystal. So, these two are usually the rate limiting steps. Now, continuing if you have a low concentration of the growth species in the vapor remember the growth species is coming here in the vapor form because we have evaporated it in some fashion. So, these are coming through the vapor phase. So, if the concentration of the growth species in the vapor phase is low then the growth process is adsorption limited there is not enough of flux of the growth species on to the growth surface. Therefore, as a at low concentrations what we have is growth rate of your crystal due to heterogeneous nucleation on the growth surface as a function of concentration of the growth species. So, at low concentrations on the left hand side you do not have enough of flux on to the growth surface therefore, the growth process is adsorption limited and essentially there is a linear increase in the growth rate as this flux of the growth species or the concentration of the growth species is gradually increased, but when the concentration of the growth species is sufficiently high then what is happening is there is a lot of impinging of the growth species on to the substrate surface, but there is too much of that happening therefore, surface reaction namely the adsorption of the species and then the joining of these species into the growing crystal that becomes the limiting step because there is too much flux not enough time so to speak not enough room for the surface reaction to proceed therefore, that becomes a the rate limiting step. Therefore, when the concentration is increased beyond a certain level concentration of the growth species in the vapor phase when that is increased beyond a certain level then what happens in the surface becomes the or what cannot happen I should say becomes the limiting step as a result of it there is a saturation of the growth rate beyond a certain level of concentration of the growth species in the vapor phase. So, this is a broad general description of heterogeneous nucleation process and what I want to recall here is that this is a very important process for nano structure growth both for example, in the formation of nano structure nano crystals quantum dots and so forth and also in the formation of films on a substrate surface as I said we will probably return to this in the next session. So, here are examples of heterogeneous nucleation nucleation of in this case evaporated silver on highly oriented pyrolytic graphite substrate HOPG stands for highly oriented pyrolytic graphite. What you can see here is that on the image on the left you have a series of dots that are essentially in a line. So, what is happening here is growth is taking place at defects along an edge. So, these are the so called edge defects. Defects often are the sites of nucleation that is where the conditions for nucleation are often more easily satisfied than in places where the crystallinity is perfect. So, defects in the HOPG edge defects then becomes they become the host for nucleation. On the right hand side is a case where you have a sample of HOPG with numerous defects on its surface and therefore, there is a more or less homogeneous nucleation of silver nano particles on the surface of the HOPG substrate from evaporated silver. So, these are specific illustrations of the formation of nano crystals from the evaporation condensation process. Then we return to the VLS process which we discussed last time the vapor liquid solid process whereby nano crystalline or rather crystalline nano wires or nano rods of semiconductors are formed because of the formation of a eutectic in this case of silicon in gold. So, what we have is a gold droplet at an elevated temperature and this is a very small droplet sized in nanometers and at this elevated temperature if you had for example flowing into this substrate if you had silane gas S I H 4 which decomposes into silicon and that silicon becomes a part of this eutectic over here and then this whole thing is sitting on a single crystal of silicon and progressively then there is the growth of or the crystallization of silicon from this eutectic and the gold droplets then gets gradually lifted due to the growth process and the growth process continues because the vapor then continuously becomes a part of this eutectic solvent from which this nano crystal gradually picks up the nutrient namely silicon to grow continuously with the orientation that is the orientation of the underlying substrate which is silicon 111. This is an example of silicon nanowires grown by the VLS method and what you can see here in a TEM micrograph transmission electron micrograph is the gold cap as we showed here this is the gold cap this is this catalyst particle that is a part of the growth process. So that gold cap is now at the top of this silicon nanowire which measures about 15 nanometers in diameter. So that forms the tip of this nanowire and you can see this forest of nanowires that are grown by the VLS method whereby one has gold nanodots that are in on a substrate and in this case for example those gold dots are not necessarily in a lithographed pattern gold dots are there and then there is a significant flux of silane that comes into it and essentially this is a an uncontrolled growth of silicon nanowires but what this illustrates is that pretty long wires this scale is 2 micrometers. So you can see that pretty long wires can be formed as a result of this process. So high aspect ratio wires can be obtained in such a way as to define a one dimensional crystal a nano crystal one dimensional system. So these are cases of or examples of gallium arsenide nanowires being grown by a similar method gallium phosphide and in this case gallium arsenide phosphide which is another compound semiconductor the point is that these examples show that this method VLS method is a versatile method to obtain nanostructured crystals or nanowires of a variety of compositions. What this graph shows over here is the temperature variation of the growth rate of nanowires of silicon and germanium both are semiconductors. So what has been done is to use silane vapor for silicon and german G H 4 vapor for germanium and the growth of nanowires by the VLS method is then that is the length of these wires is measured as a function of the growth temperature that is the temperature at which the substrate respectively silicon and germanium are maintained and these growth rates are found to depend on temperature and also on the catalyst employed it could be silver, gold, copper, nickel, palladium and so on. So what you can see here is that there is a there can be a let us remember that this is a so called Arrhenius plot that is you have the logarithm of the growth rate versus inverse absolute temperature. So this is the so called Arrhenius plot therefore what we are seeing here is an activation energy the slope of this each of these lines is the activation energy for growth under those particular conditions for that particular material. So each of them has a particular activation energy and what we see are different slopes indicating different activation energies that are involved in the growth of silicon and germanium under different catalytic influences and what you could also see is a very different rate of growth here and a rate of growth here that is you can substantially enhance the growth rate by changing the conditions under which growth is done. So remember this is a log scale so here we have growth rates in the order of 0.1 micrometer per minute here you have growth approaching 100 micrometers per minute. So very substantial changes or increase in the growth rates can be obtained by adjusting the conditions of growth appropriately. So what we have learned in this particular session is that the growth of nano crystals can be controlled by polymer stabilizers which can actually also define the shape of metallic nano crystals which allow us to get the compound semiconductor crystals of a very narrow set of dimensions that is mono disperse compound semiconductor crystals and subsequently we learned about heterogeneous catalysis or sorry heterogeneous nucleation and how heterogeneous nucleation can lead to controlled nano crystals on appropriate substrate surfaces. We will continue next time with the growth of nanowires in this case of carbon nanotubes and then move on to the growth of films through processes that lead us to nanostructures. Thank you.


What's going on guys it's your boy DPJ here today with another Destiny video in today's video we have top five sniping plays of the week now some of these are absolutely unbelievable I don't know how people are so good with snipers absolutely surprises the hell out of me I just don't get it but guys if you do enjoy the video if you can leave a like I would appreciate the support submit any of them badass clips you've got today email I just linked in the top of the video description hope you enjoyed the video and I'll catch you guys on that next one peace out till next time peace capture the zones they're all that matters enemy captured zone A zone C secure two four one triple down look at them four you're in the lead oh my god on YouTube every damn day watching these videos of the brand new games bearded the bigger they gone by DPJ Destiny gameplays weeklies J go and subscribe


The study aimed to investigate the factors related to non-adherence to multidisciplinary treatment, MDT, recommendations and the effectiveness of a smartphone-based app in improving compliance rates with MDTs in breast cancer patients. The results showed that app use was independently associated with adherence to adjuvant treatment, decreasing the non-compliance rate for chemotherapy and radiotherapy but not for anti, HER2 therapy or endocrine therapy. This article was authored by Jinyu, Jiayi Wu, Ohuang and others.