10.6092/issn.1973-9494/7938
Samples of chestnut wood taken from modern age structures in the Campania Region were subjected to chemical and physical analysis in order to examine the microstructural variations in the material as a result of exposure to microwaves with the aim of devitalising colonies of xylophages. Results showed that the use of microwaves does not lead to alterations in the structure of the wood, but does bring about variations in its hygroscopicity and permeability.
application/pdf
1973-9494
7938
en
Luca Pescione
Conservation Science in Cultural Heritage
microstructure
Elimination of Xylophages from Wood through Microwave Treatment: Microstructural Experiments
Text.Serial.Journal
https://conservation-science.unibo.it/
17
Articles
2018-03-28
2018-03-26
2018-03-28
2019-09-06
45-57
CSCH
Luca Pescione
2017
10.6092/issn.1973-9494/7938
45
Dipartimento di Ingegneria Civile, Università degli Studi di Salerno, Salerno
1973-9494
microstructure
en
57
Ates, S., Hakan Akyildiz, M., Özdemir, H., Gümüscaya, E. (2010) Technological and Chemical Properties of Chestnut Wood after Heat Treatment. <em>Romanian Biotechnological Letters</em>, 1(1).
Elimination of Xylophages from Wood through Microwave Treatment: Microstructural Experiments
https://conservation-science.unibo.it/article/download/7938/7654
17
E    LIMINATION OF XYLOPHAGES FROM WOOD THROUGH
     MICROWAVE TREATMENT: MICROSTRUCTURAL
     EXPERIMENTS

   Cesare Crova*4
   Istituto Superiore per la Conservazione ed il Restauro, Ministero dei beni e delle
   attività culturali e del turismo
   Rome, Italy

   Francesco Chiadini
   Dipartimento di Ingegneria Industriale, Università degli Studi di Salerno
   Salerno, Italy

   Luciano Di Maio
   Dipartimento di Ingegneria Industriale, Università degli Studi di Salerno
   Salerno, Italy

   Luigi Guerriero
   Dipartimento di Architettura e Disegno Industriale, Università della Campania
   Naples, Italy

   Luca Pescione
   Dipartimento di Ingegneria Civile, Università degli Studi di Salerno
   Salerno, Italy

   Keywords: microwave, structures in wood, xylophages, microstructure




                                                                                                  CONSERVATION SCIENCE IN CULTURAL HERITAGE
   1. Introduction

   The relevant literature points to the effectiveness of microwave treatment in reducing
or eliminating instances of deterioration in various types of materials caused by biologi-
cal attacks. There are reports, for example, of the positive effects regarding the eradi-
cation of herbaceous vegetation from the stone facing of architectonic monuments, as
well as annotations on the limits to be observed when utilising this technique, so as
to avoid structural alterations in the materials [1]. In the same way, the effectiveness
of microwave heating in disinfesting wooden structures under attack from xylophage
insects has also been conirmed with a series of advantages, compared to previously
used methods of chemical disinfestation: rapidity and effectiveness of the treatment;
minimisation of health risks for the operators; absence of toxic residues and VOC emis-
sions. In fact, trials have been conducted on the devitalisation of colonies of xylophages
in wooden elements (loor and rooing frames, window and door ixtures) through ex-
posure to microwaves for a period of approximately 3 minutes at a modest level of
average absorbed power, 20 W (quantiiable as the difference between the average


* Corresponding author: cesare.crova@beniculturali.it

                                                                                             45
                                                                                                          incident power of 23÷25 W and the average relected power of 3÷5 W), with the insects,
                                                                                                          no matter what their stage of development (egg, larva, pupa), being heated to the lethal
                                                                                                          temperature of approximately 60° C (Table 1; Figure 1). Although this technology is
                                                                                                          widely used for the restoration of antique furniture (placed in large-scale reverberation
                                                                                                          chambers and exposed to microwave treatments whose duration and intensity/power is
                                                                                                          set on the basis of empirical data, meaning the experience of the operators), trials have
                                                                                                          yet to be run to assess its effects on the microstructure of wood. The need for similar
                                                                                                          assessment is made even more urgent by the development of high-performance instru-
                                                                                                          ments [2, 3] and by the increasing use of on-site treatment techniques made possible
C. Crova, F. Chiadini, L. Di Maio, L. Guerriero, L. Pescione - Elimination of xylophages from wood




                                                                                                          by the introduction on the market, of microwave horn antennas and open application
                                                                                                          devices [4, 5] that can be used to radiate loor beams or roof trusses.
                                                                                                             This study has assessed the potential for application of microwave disinfestation to
                                                                                                          wooden elements dating from the past (affected by low humidity and various forms of
                                                                                                          deterioration) through instrumental analyses designed to evaluate any microstructural
                                                                                                          changes in samples of chestnut wood (Castanea sativa) subject to microwave radia-
                                                                                                          tion for pre-set periods of time at controlled levels of power.

                                                                                                                       Table 1. Surviving xylophages based on the duration of treatment [6].




                                                                                                          Figure 1. Percentage of xylophage mortality based on the temperature applied [7].




                                                                                                     46
   2. Objectives of the study

    As is widely known, microwave heating is the result of diathermy: the application
of an electromagnetic ield to a material causes the water molecules in the material to
rotate. This rotation is explained by the fact that the water molecules constitute a dipole
with a momentum that is not nil, given that, as we know, the H+ and O- atoms are not
aligned. The resulting oscillation generates kinetic energy that heats both the material
and the xylophages found inside it. Seeing that the amount of heat produced is deter-
mined by the level of humidity in the wood, the areas most responsive to the treatment
(those that heat up irst) are the ones found further inside the structure, where the
percentage of humidity is higher than in the outside layers.
    There is evidence in the literature of the effectiveness of heating in terms of
disinfestation and for reducing humidity and increasing permeability, but the con-
sequences on the chemical/performance-related features of the wood treated are
still up for discussion and there is no experimental evidence regarding the conse-
quences of the treatment on the structure of the wood. In the case of new wood,
assessments carried out to date have focused solely on performance and offer
contrasting results: in some instances, the heating reduced the wood’s properties
of mechanical resistance [8,9], while in others, these properties were found to have
increased [10].


   3. Experimental trials

   Experiments were carried out on samples of chestnut wood taken from beams
(rounded beams simply stripped of their bark and found in the main frame) and from
the “chiancarelle” (trunks of young chestnut wood smaller in diameter, split in half to
form “ginelle” and used in the secondary frame) of the loors of Palazzo δancellotti




                                                                                                   CONSERVATION SCIENCE IN CULTURAL HERITAGE
di Durazzo in Casalnuovo, near Naples [11]. A number of the samples date from
the 18th century, while others are from the 19th century; all have been extensively
exposed to biological attack (Figure 2). The samples chosen, therefore, consisted
of wood of the same species, employed for structural uses but dating from different
periods, and which had not undergone any previous treatment of preservation. To
obtain comparative data, similar samples of recent wood were also subjected to the
same experiment.
   The analyses were carried out on two types of samples, one consisting of thin ele-
ments (7.2×4.0×3.4 cm), the other of thicker pieces (7.2×7.0×3.4 cm), all of them cut
from the structural elements procured on-site, so as to render the dielectric measure-
ments both convenient and suitable for comparison.
   The heads of the beams showed evidence of fungus attack from basidiomycetes
(“cavities” with deep lines of cleavage) and from cerambycidae xylophage, as dem-
onstrated by the deep larval tunnels found in the alburnum. The “chiancarelle” trunks,
on the other hand, showed evidence of attack by common woodworm (anobium punc-
tatum), leaving the typical small-diameter holes (1-1.5 mm) from which the insects
have emerged (Figure 3).




                                                                                              47
C. Crova, F. Chiadini, L. Di Maio, L. Guerriero, L. Pescione - Elimination of xylophages from wood




                                                                                                          Figure 2. Samples of chestnut wood taken from the beam heads (above) and from the “chiancarelle”
                                                                                                          boards (below) originally found in structures of the 18th century (left) and the 19th century (right).




                                                                                                          Figure 3. Longitudinal sections of beam heads showing the damage produced by large
                                                                                                          cerambycidae larvae, alternated with undamaged pieces. Larvae tunnels reaching the alburnum
                                                                                                          are visible amidst portions of undamaged wood.

                                                                                                             The wood samples were exposed to microwaves in an aluminium reverberation
                                                                                                          chamber with an edge measuring 120 cm, powered by a 2-kW generator (magnetron)
                                                                                                          and an Alter SM 745 switching system. The power output of the magnetron is con-
                                                                                                          trolled remotely by a voltage signal of 0-10 V sent to the switch-mode power supply.
                                                                                                          The waveguide, equipped with a WR340 lange, consists of a circulator/isolator and
                                                                                                          a trunk waveguide with a directional coupler capable of providing readings of incident
                                                                                                          and relected power using an Anritsu ML 2438 A dual-channel power metre outitted
                                                                                                          with MA 2472 D sensors. The temperature is gauged by a FISO TMI 4 thermometer


                                                                                                     48
with ibre-optic sensors. The ibre-optic probe is inserted into each sample through a
hole with a diameter of 1.54 mm, down to a depth of approximately 35 mm, maintaining
adequate contact with the wood sample, so as to keep air gaps from causing inaccu-
rate temperature readings during the heating.
   The samples were heated to a temperature of roughly 60 °C for a period of exposure
of at least 3 minutes, at levels of average absorbed power of 20 W. These levels were
chosen as being characteristic of effective treatment, with the percentage of surviving
cerambycidae proving to be zero, in accordance with the literature on the subject [6].
   An initial, readily apparent effect of the heating was a decrease in the mass of
the samples. In light of the temperatures, which never exceeded 100°C, it can be
concluded that this reduction is tied to the loss of unbonded water from the samples.
An analysis of the temperatures shows that as the temperature increased in a nearly
constant (linear) fashion for both the historic and the new samples, differences were
observed in the reduction of the mass, which proved greater in the samples of historic
wood (Figure 4). This observation, together with the fact that the density of the historic
samples was signiicantly lower than that of the recent wood, makes it possible to
conclude that different quantities of unbonded water are involved (or different levels of
hygroscopicity), with the reduced quantity of water appearing to be tied to the deterio-
ration at work in the older samples.

   Pi = Power Incident = 23 ÷ 25 W ; Pr = Power Relected = 3 ÷ 5 W
   Padsorbed = 20 W (Padsorbed = Pincident – Prelected)
   T operating max = 100 ° C; t = 540 s ÷ 660 s;




                                                                                                      CONSERVATION SCIENCE IN CULTURAL HERITAGE



Figure 4. Temperature readings during the microwave heating of samples of chestnut wood from
the 18th and 19th centuries, as well as modern samples, with an incident power of 24W, up to a
maximum operating temperature of 100°C.

   Both before and after the microwave treatment, the following experimental evalua-
tions were carried out on the samples: dielectric readings, thermogravimetric analysis
(TGA), infrared spectroscopy analysis (FT-IR); optical microscope examination.
   Readings of complex permittivity were taken with an HP85070 dielectrometer con-
nected to an HP85107 vector network analyser. These readings were taken to assess
both the real portion, ’, and the imaginary portion, ’’, of the material’s permittivity,
given that wood is a non-magnetic, non-conductive medium. In taking the readings of
dielectric permittivity, the samples were alternately gauged along the ibre and across


                                                                                                 49
                                                                                                          the ibre to determine whether the anisotropy and the lack of uniformity of the material,
                                                                                                          inluence the heating or the other parameters that come into play. Various readings
                                                                                                          were taken on wood samples with similar characteristics to arrive at average values
                                                                                                          for the dielectric constants. Table 2 shows the igures for the ’ and ’’ of the different
                                                                                                          samples:

                                                                                                          Table 2. Dielectric constants of wood: ’ (real portion), ’’ (imaginary portion).

                                                                                                                        Chestnut specimens                                  1                            2

                                                                                                          18 century chestnut specimens on ibre
C. Crova, F. Chiadini, L. Di Maio, L. Guerriero, L. Pescione - Elimination of xylophages from wood




                                                                                                             th
                                                                                                                                                                      2.5 ÷ 3.5                      0.3 ÷ 0.7
                                                                                                          18th century chestnut specimens cross-ibre                  2.3 ÷ 3.6                     0.25 ÷ 0.5
                                                                                                          19th century chestnut specimens on ibre                     2.5 ÷ 2.6                     0.15÷0.35
                                                                                                          19th century chestnut specimens cross-ibre                  2.1 ÷ 2.5                     0.15 ÷ 0.3
                                                                                                          New chestnut specimens on ibre                              2.2 ÷ 2.6                     0.2 ÷ 0.38
                                                                                                          New chestnut specimens cross-ibre                            2 ÷ 2.6                      0.15 ÷ 0.33

                                                                                                             The readings of permittivity show that in the case of all the wood samples, regard-
                                                                                                          less of their age, the loss tangent ’’/ ’ was in the order of 10-2 ÷ 10-1, which represents
                                                                                                          an acceptable value for effective heating with microwaves. Given that the decrease
                                                                                                          in bonded water resulting from the microwave treatment corresponds to a variation in
                                                                                                          the electromagnetic characteristics of the materials, a comparison was made of the
                                                                                                          permittivity values and the loss tangent as measured both before and after the treat-
                                                                                                          ment, leading to the conclusion that for the materials exposed to the microwaves the
                                                                                                          heating was eficient.
                                                                                                             The average values of the coeficients of the real portion and the imaginary portion
                                                                                                          were calculated, having been determined on the basis of the loss tangents of the com-
                                                                                                          parative igures for all the samples exposed. The following table shows the average
                                                                                                          values as calculated, broken down by the different ages of the wood samples:

                                                                                                          Table 3. Evaluation of the loss tangent tan    for each category of samples and the related axis
                                                                                                          alignments.

                                                                                                                      Specimens on ibre                                         Loss factor
                                                                                                                                                                                2
                                                                                                                                                                                    /   1
                                                                                                                                                                                            = tan
                                                                                                                                New                                                     0.12
                                                                                                                            18th century                                                0.15
                                                                                                                            19th century                                                0.10

                                                                                                                    Specimens cross-ibre                                        Loss factor
                                                                                                                                                                                2
                                                                                                                                                                                    /   1
                                                                                                                                                                                            = tan
                                                                                                                                New                                                     0.11
                                                                                                                               th
                                                                                                                            18 century                                                  0.13
                                                                                                                            19th century                                                0.10



                                                                                                     50
   The point of the thermogravimetric analysis (TGA) is to determine the typical tem-
peratures of deterioration (pyrolysis) of the different constituent elements of the wood.
The trial was carried out on wood dust taken from each sample, in the vicinity of the
alburnum-duramen zone, both before and after heating. A comparison of the curves
shows a greater loss of weight by the recent wood, as compared to the 18th and 19th
century samples which presented a lower quantity of lignin, a reduction attributable to
the deterioration at work. The analysis was performed in a temperature range of Tamb –
900 °C, with a heating speed of 10 °C/min in nitrogen, at 50 mL/min, for samples weigh-
ing between 8 mg and 10 mg [12]. The use of microwaves did not produce noteworthy
divergences in the gravimetric curve, apart from a lowering of the curve between 50 °C
and 100 °C, which points to the greater loss of unbonded water, while the main compo-
nents (hemicellulose, cellulose and lignin) remained unchanged (Figure 5).




                                                                Figure 5. Overlapping
                                                                thermogravimetric curves
                                                                of the 18th century (1700s)
                                                                specimen before and after
                                                                the MW treatment (green
                                                                curves - top), of the 19th
                                                                century (1800s) specimen
                                                                before and after the MW
                                                                treatment (blue curves
                                                                - centre) and of the new




                                                                                                   CONSERVATION SCIENCE IN CULTURAL HERITAGE
                                                                specimen before and after
                                                                the MW treatment (red
                                                                curves - bottom). The pre-
                                                                and post-treatment curves
                                                                regard the same samples.
                                                                The lone difference is the
                                                                clearly visible downward
                                                                shift in the post-treatment
                                                                curves, evidence of the
                                                                greater loss of unbonded
                                                                water by the samples
                                                                that undergo microwave
                                                                treatment, as shown by
                                                                the downward inlection in
                                                                the section extending up
                                                                to 150 °C.




                                                                                              51
                                                                                                              In accordance with the relevant literature [13,14], the graphs of the resulting curves
                                                                                                          can be subdivided into four primary sections: from Tamb – to approximately 150 °C:
                                                                                                          evaporation of the water and of the volatile light compounds; from approximately 150
                                                                                                          °C to 260 °C: deterioration of the hemicellulose; from approximately 260 °C – 400 °C:
                                                                                                          deterioration of the cellulose and start of the deterioration of the lignin; from approxi-
                                                                                                          mately 400 °C – Tsup: decomposition of the lignin.
                                                                                                              Of particular interest is the infrared spectroscopy analysis (FT-IR), carried out
                                                                                                          with an interferometry spectroscope using the Fourier Transform method (FT), which
                                                                                                          serves to characterise different species of wood, though the approach is semi-de-
C. Crova, F. Chiadini, L. Di Maio, L. Guerriero, L. Pescione - Elimination of xylophages from wood




                                                                                                          structive. The behaviour observed in the radiation wavelength range from 4000 to 500
                                                                                                          cm-1 was similar for both the historic and recent materials, producing spectroscopic
                                                                                                          diagrams that resembled each other closely and proved comparable to those found in
                                                                                                          the literature [15]. The spectroscopic analysis did not reveal any noteworthy changes
                                                                                                          in the (minimum) peaks at any point along the length of the spectrum: for each wave-
                                                                                                          length of infrared radiation, the readings of the polymer components were the same,
                                                                                                          on account of the components’ stability, even after the microwave treatment. The only
                                                                                                          change was the intensiication of these peaks following heating (higher minimums),
                                                                                                          traceable to a morphological change, as conirmed by the relevant literature [16,17]. In
                                                                                                          light of the above, it can also be concluded that the microwave treatment did not result
                                                                                                          in modiications of the wood or of its constituent elements (hemicellulose, cellulose and
                                                                                                          lignin) (Figure 6).




                                                                                                          Figure 6. Overlapping FT-IR spectrums of the 18th century (1700s) specimen before and after the
                                                                                                          MW treatment (green curves - top), of 19th century (1800s) specimen before and after the MW
                                                                                                          treatment (blue curves - left) and of the new specimen before and after the MW treatment (red
                                                                                                          curves - right).

                                                                                                            Table 4 below presents the wave peak number associated with the polymeric com-
                                                                                                          ponent evaluated, together with the status of the peak:


                                                                                                     52
Table 4. Identiication and attribution of the peaks of the infrared spectrums.

  Characteristic peaks (cm-1)          Peak level              Polymeric component

            3600-3200                     intense                   Stretching OH
                1715                     medium                 Xylan (hemicellulose)
                1607                     medium                          Lignin
                1453                       weak                          Lignin
                1323                      intense                      Cellulose
                1216                     medium                          Lignin
                1157                     medium                          Lignin
                1030                      intense                 Polysaccharide
                                                            (hemicellulose and cellulose)
                895                        weak                   Polysaccharide
                                                            (hemicellulose and cellulose)

    The irst conclusion to be reached from the FTIR analysis is that the spectrums of
the three wood samples, though originating from different periods, present the same
peaks, indicating a nearly identical composition. This translates into an absence of
deterioration which, on the other hand, would have been present, had differences in
the types and numbers of peaks found along the spectrum been observed. At the same
time, it can be noted that, in the case of all three samples, the spectrums generated
by the analysis carried out following the microwave treatment present a slight differ-
ence in intensity: one that proves greater for the treated samples. The difference is
more acute in the case of the new wood, as opposed to the old, with this heightened




                                                                                                  CONSERVATION SCIENCE IN CULTURAL HERITAGE
intensity seeming to point to a slight increase in the density of the sample following the
microwave treatment, corresponding, as was shown by the TGA analysis as well, to a
gradual, heightened loss of unbonded water on the part of the more recent samples,
as opposed to those from the more distant past.
    The observations made with an optical microscope, by means of transmitted light,
also provide conirmation of the feasibility of using microwaves for xylophage disinfes-
tation; in fact the samples, viewed both before and after treatment - and regardless of
whether they were historic or new, even when viewed at different levels of enlargement
- did not present visual differences, preserving the same coniguration and the same
dimensions of the constituent elements of the parenchymatous tissue, just as was
observed for the dimensions of the primary constituent parts (Figure 7).
    In the image shown in Figure 7, obtained with an optical microscope at an enlarge-
ment of 5x, the main constituent parts of the structure of the chestnut wood can be
identiied, with highlights including portions of the early wood (darker in colour, with
veins of larger diameter) and portions of late wood (more lightly shaded, with veins of
smaller diameter). The change from late wood to early wood points to the start of a new
growth ring, indicating the dating, and thus the age, of the element. The arrangement
of the parenchymatous radii can be observed in the image, as shown by the continu-
ous black horizontal lines and the thick array of points distributed uniformly throughout
the section, coinciding with the wood ibres.



                                                                                             53
C. Crova, F. Chiadini, L. Di Maio, L. Guerriero, L. Pescione - Elimination of xylophages from wood




                                                                                                          Figure 7. Transversal section examined under optical microscope (5x).




                                                                                                          Figure 8. Radial section examined with optical microscope, pre-treatment (on left, 5x), post-
                                                                                                          treatment (on right, 20x).



                                                                                                             4. Discussion

                                                                                                             The experimentation carried out on the use of microwaves to disinfest chestnut
                                                                                                          wood under attack from xylophages has shown that the utilisation of this technique
                                                                                                          does not lead to modiications in the structure of the wood or in its primary constituent
                                                                                                          elements (hemicellulose, cellulose and lignin), whereas it does give rise to variations in
                                                                                                          hygroscopicity and permeability. These effects are more apparent in the historic wood
                                                                                                          samples, which showed reduced quantities of bonded water, while at the same time,
                                                                                                          no secondary effects of deterioration in the structure of the wood was observed.




                                                                                                     54
      5. Conclusions

   In the future, there will be other ields of research to explore involving the use of
microwave heating. Of particular importance will be ongoing efforts to evaluate the
effects of this technology on wood structures of cultural interest, with a special focus
on: permeability to water; evaluation of the properties of transport within the wood
structureν conirmation of the morphology of the main constituent elements through
speciic analyses (X-ray diffraction)ν the compatibility of the treatment for wood ele-
ments decorated with tempera paint or covered with “overlays” (determining whether
the painted portions would be damaged or if there is a risk of the overlays detaching
from the wood support).


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                                                                                                            Biographical notes

                                                                                                             Cesare Crova graduated in Architecture; he is a specialist in Restoration of Monu-
                                                                                                          ments and has a Ph.D. in Conservation of Architectural Heritage; he is a professor
                                                                                                          in Architecture Pathology at ISCR SAF. He has carried out teaching and research at
                                                                                                          IUAV, the “Sapienza” University of Rome, the University of Molise and the Cultural
                                                                                                          Heritage Department at the University of Padua. He works in the ield of cultural herit-
                                                                                                          age conservation, where he is part of several working groups at MiBACT, in addition to
                                                                                                          planning and directing restoration work. He is the National Vice President of Italia Nos-
                                                                                                          tra and a member of the CDA of the Circeo National Park; he is a committee member of
                                                                                                          the UNI Technical Corps at UNI / CT 033 / SC 01 / GL 01 “Guidelines and terminology”
                                                                                                          and a member of MiBACT Unite 4 Heritage (MiBACT H4U), “Blue Culture Helmets “.

                                                                                                              Francesco Chiadini is an electronics engineer, Ph.D. in Information Engineer-
                                                                                                          ing and researcher at the Department of Industrial Engineering at the University of
                                                                                                          Salerno. He has been Chairman of many international congress sessions; Research
                                                                                                          Scholar at Pennsylvania State University (PA-USA); Science Monitor at Livingston’s
                                                                                                          Laser Interferometer Gravitational Wave Observatory (LA-USA); Member of the Inter-
                                                                                                          national Doctoral Program for the assignment of the Doctor of Research at the Fakultät
                                                                                                          für Mathematik und Informatik at the FernUniversität in Hagen; Member of the Local
                                                                                                          Workshop IV Workshop on Metamaterials and Special Materials for Electromagne-
                                                                                                          tism and Telecommunication (MMSM 2008). He is currently a member of the Program
                                                                                                          Committee for the Optics + Photonics Conference: Nanostructured Thin Films and
                                                                                                          the Smart Structures / NDE Program Committee - Bioinspiration, Biomimetics, and
                                                                                                          Bioreplication Conference. He has been elevated to the rank of Senior Life Member
                                                                                                          of the SPIE Scientiic Society “in recognition of the signiicant contribution given to the
                                                                                                          Scientiic Community in Optics and Photonics”.

                                                                                                             Luciano Di Maio, engineer of Industrial Technologies at Chimico-Food, Ph.D. in
                                                                                                          Chemistry and New Materials Research. From 1999 to 2004, he was a researcher of
                                                                                                          Principles of Chemical Engineering. Since 2005, he has been an Associate Professor
                                                                                                          of Science and Technology of Materials, Faculty of Engineering, University of Salerno,


                                                                                                     56
where he teaches courses for the Degree in Chemical Engineering, Civil Engineering,
Degree courses in Food Engineering and the Single Cycle Degree in Architecture En-
gineering. He is a Member of the Board of Directors of the Interdepartmental Research
Center at the University of Salerno “Nanomaterials and Nanotechnologies (NANO -
MATES)”; member of the selective exam committee for university researchers; chair-
man and member of commissions for the conferment of research grants; referee of
the international magazine “Polymer Engineering & Science” and a member of various
scientiic associationsν an aggregate member of the State Examinations Committee for
the license to practice as an engineer; chairman of the guidance and tutoring commit-
tee of the Academic Council for Chemical Engineering.

   Luigi Guerriero graduated in Architecture; he has a Ph.D. in Conservation of Ar-
chitectural Heritage. Since 2000 he has been an associate professor of Restoration
at the Faculty of Architecture of the II University of Naples. He has organized and di-
rected research groups. He has coordinated national scientiic initiatives. He has been
a member on the scientiic council for national meetings and exhibitions. His research
concerns the theories and history of restoration, particularly regarding the protagonists
and interventions of the mid-twentieth century, the mensiochronologic characterization
of traditional constructive elements, with the related protocol of analysis of deteriora-
tion and of structural modeling and the methods and techniques of urban restoration.

   Luca Pescione graduated in Construction Engineering and Architecture at the Uni-
versity of Salernoν his studies cover the experimental ield of Chemistry and Tech-
nology for the Restoration and Conservation of Materials, with particular regard to
microwave processing in the restoration of eighteenth-century wooden elements. He
is mainly engaged in architectural design and restoration, both as a freelancer and in
specialized companies.




                                                                                                     CONSERVATION SCIENCE IN CULTURAL HERITAGE
    Summary
    Samples of chestnut wood taken from modern age structures in the Campania Re-
gion were subjected to chemical and physical analysis in order to examine the micro-
structural variations in the material as a result of exposure to microwaves with the aim
of devitalising colonies of xylophages. Results showed that the use of microwaves
does not lead to alterations in the structure of the wood but does bring about variations
in its hygroscopicity and permeability.

   Riassunto
   Campioni di legno di castagno, estratti da strutture campane di età moderna, sono
sottoposti ad indagini chimiche e isiche, allo scopo di evidenziare le variazioni micro-
strutturali indotte sul materiale dall’esposizione alle microonde inalizzata alla devitaliz-
zazione di colonie di insetti xilofagi. I risultati sperimentali mostrano che l’impiego delle
microonde non de-termina alterazioni nella struttura del legno, ma induce variazioni di
igroscopicità e di permeabilità.




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