A2-AJB-11(9) 2204-2209- 2012

African Journal of Biotechnology Vol. 11(9), pp. 2204-2209, 31 january, 2012 Available online at http://www.academicjournals.org/AJB DOI: 10.5897/AJB11.3052 ISSN 1684–5315 © 2012 Academic Journals

Full Length Research Paper

Effects of heat treatment on density, dimensional stability and color of Pinus nigra wood

Bilgin Guller

Forest Products Engineering Department, Faculty of Forestry, Suleyman Demirel University, Isparta, Turkey. E-mail:

[email protected]. Tel: +902462113970. Fax: +90 246 2371810.

Accepted 18 January, 2012

The purpose of this study was to evaluate the effect of heat treatment on some physical properties and color change of Pinus nigra wood which has high industrial use potential and large growing stocks in Turkey. Wood samples which comprised the material of the study were obtained from an industrial plant. Samples were subjected to heat treatment process of varying temperatures (190, 200, 212 and 225°C) and durations (60, 120 and 180 min). After these processes, density and swelling of the wood samples were tested in comparison with untreated ones. The results show that density decreased (2.57 to 12.6%) as treatment temperature and duration increased. Dimensional stability was improved (up to 66%) with the extent of the circumstances mainly depending on treatment temperature. Color became uniformly darker with increasing temperature and durations. Temperature had clearly greater influence on investigated properties than duration. Key words: Pinus nigra, heat treatment, temperature, color change.

INTRODUCTION Wood, as a renewable natural resource, has been used by humans for thousands of years. Since instability under changing moisture and biodegradability are major disadvantages of the material, considerable amount of research have been conducted on this topic. Heat treat-ment is a wood modification method being applied to improve dimensional stability and durability of the material (Esteves and Pereira, 2009). After heat treat-ment, the color of the wood changes, and the new color becomes uniform throughout the thickness of wood. Thus, thermal modification can be used to make a low-value wood to look like a high-value wood (Gunduz et al., 2009). In recent years, a broadening range of heat-treated softwood and temperate hardwood products have been marketed as alternatives to tropical hardwood for the external joinery and furniture applications. There are 30 companies across Europe operating thermal treatment plants with a total capacity of about 300,000 m3. Approximately 40, 13, 12, 8% of this capacity is in Finland, Germany, Netherland and Estonia, respectively. The remaining is distributed in France, Croatia, Austria, Switzerland, Sweden and Turkey (Anonymous, 2011). Since there is no chemical application during the process, heat-treated wood is considered as an eco-friendly

method which is an alternative to chemically impregnated wood materials (Rapp, 2001; Anonymous, 2003). A good literature review on wood modification by heat treatment, history and methods is done by Esteves and Pereira (2009). Depending on the variation of all heat treatment processes (industrial-scale, semi industrial scale or laboratory experiments), the properties of heat treated wood also vary. The extent of change in wood properties during heat treatment mainly depends on the heat treatment method, tree species and its wood charac-teristics, initial moisture content of the wood, the surrounding atmosphere and treatment temperature and time. Temperature has greater influence on many pro-perties than time (Mitchell, 1988; Rapp, 2001; Hill 2006; Esteves and Pereira, 2009). ThermoWood, developed by VTT in Finland, is an industrial-scale heat treatment process that has been widespread in the market. With high temperatures of this treatment, bending strength is reduced to 30%. A considerable (from 50 to 90%) reduction in shrinking and swelling is reported after the treatment (Homan and Jorissen, 2004; Sahin Kol, 2010).

The main purpose of this study was to determine industrial heat treatment effects on some physical proper- ties of Pinus nigra wood under varying temperatures and

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durations, which would give an opportunity for reduction of the process time. MATERIALS AND METHODS Wood samples used for this study were obtained from an industrial plant. Lumbers were stored and pre-dried at lumberyard in the conditions of 49% average relative humidity and 25°C air temperature. The thermal treatment was carried out in a prototype furnace of a forest product company following an industrial process called ThermoWood. Since the collaborated company has strict rules to keep the details of the process, only general mechanism of the process was mentioned here. In the process, wood was heated in the conditions of low air contents (under 3.5%) and in the presence of water steam. These conditions prevent wood material from burning at high temperature. Temperatures for the process range from 150 to 240°C, the time of duration range from 0.5 to 4 h (Homan and Jorissen, 2004). The temperature used for the actual heat treatment period is 212°C and duration of such temperature is 120 min for softwood species in the company where lumbers were planed, saw and test samples from sap wood were obtained. Control samples were cut from half of the lumbers. Heat treatment was applied at four different temperatures (190, 200, 212 and 225°C) and at three different duration (60, 120 and 180 min). Density of samples was measured according to ISO standard (ISO/CD 13061-2). As a result of the fact that wood density is a highly variable property between and within trees, the use of decrease density in percent to evaluate treatment effects was preferred. Percentage decrease in density was calculated by using control samples of each treatment. Dimensional stability was determined by measuring the volumetric swelling percentage of the samples which were immersed in a water bath at a controlled temperature of 20°C. During the tests, the water in the water bath was re-circulated continuously to maintain the required temperature of 20°C (Dubey, 2010). Swelling measurements of the samples were measured with 0.01 mm accuracy at three different marked positions before and after immersion in water for 2, 4, 8, 24, 48 and 72 h. Then, the specimens were weighed every 24 h and, once the weight changes of the test specimens were less than 0.1%, it was assumed that the specimens had reached equilibrium. The weight was measured with an accuracy of ±0.001 g. The dimensions in longitudinal, width (tangential) and thickness (radial) directions were measured to an accuracy of ±0.01 mm. The volumetric swelling coefficient (S) was determined by Equation (1) (Rowell and Youngs, 1981) given below:

1001

12(%)S x

V

VV −= (1)

Where, V2 is the wood volume after wetting with water; V1 is the wood volume of oven dried sample before wetting.

Three replicates of untreated and treated specimens were used for each test. A variety of terms is used to describe the degree of dimensional stability given to wood by treatments: Antishrink efficiency, swelling percent, dimensional stabilization efficiency, antiswelling efficiency and percent reduction in swelling (R). We used antiswelling efficiency (ASE) and it was determined using the following Equation (2) (Rowell and Youngs, 1981):

1001

12(%)ASE x

S

SS −= (2)

Where, S2 is the treated volumetric swelling coefficient; S1 is the

Guller 2205 untreated volumetric swelling coefficient.

Color of samples was measured according to ISO 7724/1-2-3 the tangential surface before and after heat treatment by a Minolta Croma-Meter CR-400 colorimeter. The sensor head was 6 mm in diameter. Measurements were made using a D65 illuminant and a 10-degree Standard observer. Percentage of reflectance, collected at 10-nm intervals over the visible spectrum (from 400 to 700 nm), was converted into the CIELAB color system, where L* describes the lightness and a* and b* describe the chromatic coordinates on the green-red and blue-yellow axes, respectively. From the L*, a* and b*values, the difference in the lightness (∆L*) and chroma coordinates (∆a* and ∆b*) were calculated using group mean values. ∆L*, ∆a* and ∆b* are the changes between pre and post treatment values. These values were used to calculate total color change (∆E*) according to Equation (3) (ISO 7724/3):

2/1222]*)(*)(*)[(* baLEab ∆+∆+∆=∆ (3)

Variance analysis was applied for the results of this study. All statistical calculations were based on the 95% confidence level. Tukey’s multiple range tests was used to determine the differences among treatments. Considering variations of four different temperatures, three process durations and particularly six different immersion times in water for the determination of swelling, the results were preferably given with simplified and understandable figures or tables and the important statistics were indicated in the text. Heat treated lumbers were evaluated visually in terms of quality in particular cracks. RESULTS AND DISCUSSION When compared with the control sample, wood density decreased with increasing time and temperature. The result is parallel to previously published report for different species (Ghalehno and Nazerian, 2011; Gunduz et al., 2009, Kaygin et al., 2009; Korkut and Guller, 2008; Yildiz et al., 2006). The highest decrease (12.6%) in density occurred at 225°C and 180 min, the lowest one (2.57%) was at 190°C and 60 min (Table 1).

According to statistical test on variation estimates for wood density decrease, temperature (62%) and duration (26%) are important sources of variations. On the other hand, the magnitude of temperature x duration inter-actions (5%) has lower importance than individual effects on the variation of wood density decrease. It means treatment temperature is more effective than the time duration and this result is consistent with some previous studies (Mitchell, 1988; Rapp, 2001; Hill 2006; Esteves and Pereira, 2009). The conditions of treatment differ among published works. Instead of extending this paper by comparing previous works which applied different conditions, a realistic point of view and focus on the studies including at least close conditions and/or species was done. For 190°C and 180 min duration, the density decrease of hornbeam wood was 4.88% by Ghalehno and Nazerian (2011) which is very close to that of the current result. However, at the same temperature and duration, and similar process for Scots pine, the result was reported to be about 3% (Kortelainen et al., 2006). The material of the reference works was 70°C kiln dried;

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2206 Afr. J. Biotechnol.

Table 1. Decrease (%) in P. nigra wood density after heat treatment.

Duration (min) Temperature (°C) N Mean Standard error

60

190 40 2.567 0.300 200 40 2.638 0.105 212 40 6.451 0.086 225 40 8.194 0.172

120

190 40 4.457 0.576 200 40 4.821 0.034 212 40 8.150 0.175 225 40 10.698 0.192

180

190 40 5.244 0.490 200 40 7.837 0.369 212 40 8.759 0.164 225 40 12.602 0.303

on the other hand, samples of the current study was naturally pre-dried in different conditions and this may be the probable cause of the difference between the results. For paulownia wood at 200°C and 180 min duration, density lose was found to be approximately 10% (Kaygin et al., 2009) which is 2% higher than that of our result. Akyildiz et al. (2009) reported approximately 13% density lost (12.7 for oven dry and 13.4 for air dry density) for P. nigra heat treated wood under 230°C and 8 h. The result is similar to this study result (12.6%) of 225°C and 180 min. The depolymerization reactions of wood polymers are the main cause of the density decreases. Above a certain temperature, the physical characteristics of hemicelluloses (127 to 235°C), lignin (167 to 217°C) and the cellulose (231 to 253°C) changes (Boonstra et al., 2007). Hemicellulose, which is less stable to heat effect than cellulose and lignin, plays important role in the decrease of physical properties of wood at high temperatures (Fengel and Wegener, 1989; Hillis, 1984).

As compared to the control group, heat treatments resulted in a significant (P < 0.05) reduction in swelling percent of wood, especially long time durations in water. The general trend is that volumetric swelling of wood decreases with increasing treatment temperature and durations (Figure 1). When compared with both the actual time and duration (212°C and 120 min) in practice and suggested ones (230°C and 120 min) which were obtained in laboratory conditions by Akyildiz et al. (2009), the current promising results of higher temperature (230°C) with a shorter duration (60 min) would present a possibility of having time reduction in practice for P. nigra.

Anti swelling efficiencies (ASE) of samples are shown in Figure 2. The highest ASE of 56 to 66% was found in the samples treated at 225°C for 180 min. The second one was 225°C for 120 min. The lowest ASE was found in 190°C for 60 min (7 to 13%). The standard errors of

means ranged from 0.13 to 0.71 among treatments. According to multiple comparison test results, there was no statistical difference (P<0.005) in the ASE for some treatments, that is, between 225°C, 60 min and 212°C, 120 min; 200°C, 60 min and 190°C, 120 min with no quality difference according to visual interpretation. This clearly indicates that treatment temperature is more effective on ASE than duration, especially treatment tem-perature of over 200°C. Dimensional stability is an important property of wooden material, particularly for the use under high humidity conditions. Thus, many studies have been conducted on this topic. Reported results on wood stability reductions (%) vary from one study to another one. These changes may explain differentiation of the heat treatment methods, standards and wood species. However, the general consensus is that heat treated wood has an advantage in terms of wood stability as compared to untreated ones (Hillis, 1984; Viitaniemi, 1997; Akyildiz and Ates, 2008; Korkut and Guller, 2008; Kaygin et al., 2009; Sahin Kol, 2010; Karlsson et al., 2011; Aydemir et al., 2011; Poncsac et al., 2011)

The availability and/or accessibility of the free hydroxyl groups of the wood play an important role in water sorption (Boonstra and Tjeerdsma, 2006). Degradation of carbohydrates and especially hemicelluloses causes a reduction in available free polar adsorption sites mainly of hydroxyl groups, including the free hydroxyl groups of water (Burmester, 1975; Feist and Sell, 1987; Hillis, 1984; Kartal et al., 2007; Aydemir et al., 2011). Irrever-sible hydrogen bond in the course of water movements within the pore system of the cell walls (Borrega and Karelampi, 2010) increase in the relative proportion of the crystalline cellulose, in which the hydroxyl groups are not easily accessible to water molecules (Pott, 2004) and cross linking of the lignin network (Tjeerdsma et al. 1998) might hinder the accessibility of free hydroxyl groups to

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Figure 1. Swelling (%) of heat treated and untreated wood samples

Figure 2. Antiswelling efficiency (ASE) of heat treated and untreated wood samples

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2208 Afr. J. Biotechnol.

Table 2. Effect of heat treatment on color properties of P. nigra.

Temperature (°C) Duration (min) L* a* b* ∆∆∆∆L* ∆∆∆∆a* ∆∆∆∆b* ∆∆∆∆E*

Control - 67.849 12.960 18.911

190 60 54.921 11.113 18.791 -12.928 -1.847 -0.120 13.060 120 47.793 11.511 17.150 -20.056 -1.449 -1.641 20.175 180 44.197 11.237 15.934 -23.652 -1.723 -2.857 23.886

200 60 42.719 10.322 15.141 -25.130 -2.638 -3.650 25.530 120 37.866 10.947 13.362 -29.983 -2.013 -5.429 30.537 180 34.286 9.833 10.976 -33.563 -3.127 -7.815 34.602

212 60 41.040 9.354 12.871 -26.809 -3.606 -5.920 27.691 120 36.610 9.672 13.312 -31.239 -3.288 -5.479 31.886 180 33.616 9.234 12.944 -34.233 -3.726 -5.847 34.928

225 60 31.750 9.824 11.558 -36.099 -3.136 -7.233 36.950 120 29.610 8.738 10.010 -38.239 -4.222 -8.781 39.461 180 23.165 4.255 5.195 -44.684 -8.705 -13.596 47.511

water (Pizzi et al., 1994). Furthermore, at very high temperatures (over 200°C), hemicelluloses may be changed to less hygroscopic substances like furfural polymers (Kamdem et al., 2002). Therefore, improved dimensional stability and water repellency of heat-treated wood are mainly due to decomposition or transformation of hemicelluloses at high temperatures.

The samples treated at 225°C were found to be darker than the other samples. The color values for the different temperatures showed clear effect of temperature on color changes. In this study, L*, a* and b* values decreased after heat treatments. The highest and lowest decreases in L* were found for the treatments at 225°C for 180 min and 190°C for 60 min (Table 2). The negative value of lightness (∆L*) and chromaticity coordinates (∆a*and ∆b*) indicated that color became darker with increase in temperature and durations. According to Fengel and Wegener (1989) and Sundqvist (2002), the reason for color changes is the production of chromospheres as a result of the hydrolytic reactions that occur during heat treatment. The extent of thermal degradation is directly related to the extent of the darkening of the color properties (Kawamura et al., 1996). The extent of change in color to black for the treatment of 225°C and 180 min, is an important aspect to consider in applications where the esthetic properties are of importance. Longer duration of time and/or higher temperature gives the wood a darker color. Therefore, the color can be used as an indicator of the severity of process conditions. However, the attained darker color after heat treatment is not stable against light exposure (Mitsui et al., 2003) and there has not been any cost-effective and easy method described to prevent this fading (Kaygin et al., 2009).

Conclusions Depending on the time and temperature, heat treatment caused decrease (2.57 to 12.6%) in wood density of P. nigra; on the other hand it caused considerable gain (up to 66%) in wood stability, especially for long time immersions (more than 24 h) in wetting conditions. Results show that it is possible to have similar wood stability, applying high temperature and shorter time duration instead of lower temperature and longer durations for P. nigra. Longer heating time and high tem-peratures increase significantly the cost of the process. Any reduction in the duration of the thermal process without any deterioration of wood quality saves energy and increases productivity. In this study, only visual comparisons were made to compare samples quality after treatments. So, more detailed investigations may be required in the aspects of wood quality and energy. ACKNOWLEDGEMENTS The author is grateful to NOVA and BHB forest products companies in Turkey for their help and he sincerely thanks Abdulkadir Soyguder for his invaluable help in communicating with the companies and for transportation possibilities. REFERENCES Akyildiz MH, Ates S (2008). Effect of heat treatment on equilibrium

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Akyildiz MH, Ates S, Özdemir H (2009). Technological and chemical

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Boonstra MJ, Van Acker J, Tjeerdsma B F, Kegel EV (2007). Strength properties of thermally modified softwoods and its relation to polymeric structural wood constituents, Ann. For. Sci. 64: 679-690.

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Editor-In-Chief George Nkem Ude, Ph.D Plant Breeder & Molecular Biologist Department of Natural Sciences Crawford Building, Rm 003A Bowie State University 14000 Jericho Park Road Bowie, MD 20715, USA Tel: (301)860-3347 (Office) Email: [email protected] Editor N. John Tonukari, Ph.D Department of Biochemistry Delta State University PMB 1 Abraka, Nigeria Email: [email protected] Associate Editors Prof. Dr. AE Aboulata Plant Path. Res. Inst., ARC, POBox 12619, Giza, Egypt 30 D, El-Karama St., Alf Maskan, P.O. Box 1567, Ain Shams, Cairo, Egypt Email: [email protected] Dr. S.K Das Department of Applied Chemistry and Biotechnology, University of Fukui, Japan E-mail: [email protected] Prof. Okoh, A. I Applied and Environmental Microbiology Research Group (AEMREG), Department of Biochemistry and Microbiology, University of Fort Hare. P/Bag X1314 Alice 5700, South Africa E-mail: [email protected]. Dr. Ismail TURKOGLU Department of Biology Education, Education Faculty, Fırat University, Elazığ, Turkey E-mail: [email protected] Prof T.K.Raja, PhD FRSC (UK)

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Department of Biotechnology PSG COLLEGE OF TECHNOLOGY (Autonomous) (Affiliated to Anna University) Coimbatore-641004, Tamilnadu, INDIA. www.psgtech.edu E-mail: [email protected], [email protected] Dr. George Edward Mamati Horticulture Department, Jomo Kenyatta University of Agriculture and Technology, P. O. Box 62000-00200, Nairobi, Kenya. Email: [email protected] Dr. Gitonga Kenya Agricultural Research Institute, National Horticultural Research Center, P.O Box 220, Thika, Kenya. Email: [email protected]

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Prof. Sagadevan G. Mundree Department of Molecular and Cell Biology University of Cape Town Private Bag Rondebosch 7701 South Africa E-mail: [email protected] Dr. Martin Fregene Centro Internacional de Agricultura Tropical (CIAT) Km 17 Cali-Palmira Recta AA6713, Cali, Colombia E-Mail: [email protected] Prof. O. A. Ogunseitan Laboratory for Molecular Ecology Department of Environmental Analysis and Design University of California, Irvine, CA 92697-7070. USA E-mail: [email protected] Dr. Ibrahima Ndoye UCAD, Faculte des Sciences et Techniques Departement de Biologie Vegetale BP 5005, Dakar, Senegal. Laboratoire Commun de Microbiologie IRD/ISRA/UCAD BP 1386, Dakar E-mail: [email protected] Dr. Bamidele A. Iwalokun Biochemistry Department Lagos State University P.M.B. 1087. Apapa – Lagos, Nigeria E-mail: [email protected] Dr. Jacob Hodeba Mignouna Associate Professor, Biotechnology Virginia State University Agricultural Research Station Box 9061 Petersburg, VA 23806, USA E-mail: [email protected] Dr. Bright Ogheneovo Agindotan Plant, Soil and Entomological Sciences Dept University of Idaho, Moscow ID 83843, USA E-mail: [email protected]

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Dr. A.P. Njukeng Département de Biologie Végétale Faculté des Sciences B.P. 67 Dschang Université de Dschang Rep. du CAMEROUN E-mail: [email protected] Dr. E. Olatunde Farombi Drug Metabolism and Toxicology Unit Department of Biochemistry University of Ibadan, Ibadan, Nigeria E-mail: [email protected] Dr. Stephen Bakiamoh Michigan Biotechnology Institute International 3900 Collins Road Lansing, MI 48909, USA E-mail: [email protected] Dr. N. A. Amusa Institute of Agricultural Research and Training Obafemi Awolowo University Moor Plantation, P.M.B 5029, Ibadan, Nigeria E-mail: [email protected] Dr. Desouky Abd-El-Haleem Environmental Biotechnology Department & Bioprocess Development Department, Genetic Engineering and Biotechnology Research Institute (GEBRI), Mubarak City for Scientific Research and Technology Applications, New Burg-Elarab City, Alexandria, Egypt. E-mail: [email protected] Dr. Simeon Oloni Kotchoni Department of Plant Molecular Biology Institute of Botany, Kirschallee 1, University of Bonn, D-53115 Germany. E-mail: [email protected] Dr. Eriola Betiku Chemical Engineering Department, Obafemi Awolowo University, Ile-Ife, Osun State, Nigeria. Present address: German Research Centre for Biotechnology, Biochemical Engineering Division, Mascheroder Weg 1, D-38124, Braunschweig, Germany E-mail: [email protected] Dr. Daniel Masiga International Centre of Insect Physiology and Ecology, Nairobi, Kenya [email protected] Dr. Essam A. Zaki Genetic Engineering and Biotechnology Research Institute, GEBRI, Research Area, Borg El Arab, Post Code 21934, Alexandria Egypt E-mail: [email protected] Dr. Alfred Dixon International Institute of Tropical Agriculture (IITA) PMB 5320, Ibadan Oyo State, Nigeria

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E-mail: [email protected] Dr. Sankale Shompole Dept. of Microbiology, Molecular Biology and Biochemisty, University of Idaho, Moscow, ID 83844, USA. E-mail: [email protected] Dr. Mathew M. Abang Germplasm Program International Center for Agricultural Research in the Dry Areas (ICARDA) P.O. Box 5466, Aleppo, SYRIA. Email: [email protected] Dr. Solomon Olawale Odemuyiwa Pulmonary Research Group Department of Medicine 550 Heritage Medical Research Centre University of Alberta Edmonton Canada T6G 2S2 E-mail: [email protected] Prof. Anna-Maria Botha-Oberholster Associate Professor: Plant Molecular Genetics Department of Genetics Forestry and Agricultural Biotechnology Institute Faculty of Agricultural and Natural Sciences University of Pretoria ZA-0002 Pretoria, South Africa Email: [email protected] [email protected] Dr. O. U. Ezeronye Department of Biological Science Michael Okpara University of Agriculture Umudike, Abia State, Nigeria. Email: [email protected] Dr. Joseph Hounhouigan Maître de Conférence Sciences et technologies des aliments Faculté des Sciences Agronomiques Université d'Abomey-Calavi 01 BP 526 Cotonou République du Bénin Email: [email protected] [email protected] [email protected] Prof. Christine Rey Dept. of Molecular and Cell Biology, University of the Witwatersand, Private Bag 3, WITS 2050, Johannesburg, South Africa E-mail: [email protected] Dr. Kamel Ahmed Abd-Elsalam Molecular Markers Lab. (MML) Plant Pathology Research Institute (PPathRI) Agricultural Research Center, 9-Gamma St., Orman, 12619, Giza, Egypt E-mail: [email protected] Dr. Jones Lemchi International Institute of Tropical Agriculture (IITA) Onne, Nigeria E-mail: [email protected]

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Prof. Greg Blatch Head of Biochemistry & Senior Wellcome Trust Fellow Department of Biochemistry, Microbiology & Biotechnology Rhodes University Grahamstown 6140 South Africa Email: [email protected] Dr. Beatrice Kilel P.O Box 1413 Manassas, VA 20108 USA Email: [email protected] Dr. Jackie Hughes Virologist Research-for-Development International Institute of Tropical Agriculture (IITA) Ibadan, Nigeria Email: [email protected] Dr. Robert L. Brown Southern Regional Research Center, U.S. Department of Agriculture, Agricultural Research Service, New Orleans, LA 70179. Email: [email protected] Dr. Deborah Rayfield Physiology and Anatomy Bowie State University Department of Natural Sciences Crawford Building, Room 003C Bowie MD 20715,USA Email: [email protected] Dr. Marlene Shehata Part-Time Professor of Pharmacology (APTPUO) University of Ottawa Heart Institute Genetics of Cardiovascular Diseases 40 Ruskin Street K1Y-4W7, Ottawa, ON, CANADA Email: [email protected] Dr. Hany Sayed Hafez The American University in Cairo, Egypt Tel: 0020105866670 Email: [email protected] [email protected] Dr. Clement O. Adebooye Department of Plant Science Obafemi Awolowo University, Ile-Ife Nigeria Email: [email protected] Dr. Ali Demir Sezer Marmara Üniversitesi Eczacilik Fakültesi, Tibbiye cad. No: 49, 34668, Haydarpasa, Istanbul, Turkey Email: [email protected] Dr. Ali Gazanchain P.O. Box: 91735-1148, Mashhad, Iran. Email: [email protected] [email protected]

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Dr. Anant B. Patel Centre for Cellular and Molecular Biology Uppal Road, Hyderabad 500007 India Email: [email protected]. Prof. Arne Elofsson Department of Biophysics and Biochemistry Bioinformatics at Stockholm University, Sweden Email: [email protected] Prof. Bahram Goliaei Departments of Biophysics and Bioinformatics Laboratory of Biophysics and Molecular Biology University of Tehran, Institute of Biochemistry and Biophysics Iran Email: [email protected] Dr. Nora Babudri Dipartimento di Biologia cellulare e ambientale Università di Perugia Via Pascoli Italy Email: [email protected] Dr. S. Adesola Ajayi Seed Science Laboratory Department of Plant Science Faculty of Agriculture Obafemi Awolowo University Ile-Ife 220005, Nigeria Email: [email protected], [email protected] Dr. Yee-Joo TAN Department of Microbiology Yong Loo Lin School of Medicine, National University Health System (NUHS), National University of Singapore MD4, 5 Science Drive 2, Singapore 117597 Singapore Email: [email protected] Prof. Hidetaka Hori Laboratories of Food and Life Science, Graduate School of Science and Technology, Niigata University. Niigata 950-2181, Japan E-mail: [email protected] Prof. Thomas R. DeGregori University of Houston, Texas 77204 5019, USA Email: [email protected] Dr. Wolfgang Ernst Bernhard Jelkmann Medical Faculty, University of Lübeck, Germany Email: [email protected] Dr. Moktar Hamdi Department of Biochemical Engineering, Laboratory of Ecology and Microbial Technology National Institute of Applied Sciences and Technology. BP: 676. 1080, Tunisia Email: [email protected]

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Dr. Salvador Ventura Department de Bioquímica i Biologia Molecular Institut de Biotecnologia i de Biomedicina Universitat Autònoma de Barcelona Bellaterra-08193 Spain Email: [email protected] Dr. Claudio A. Hetz Faculty of Medicine, University of Chile Independencia 1027 Santiago, Chile Tel: 617-432-0622 Email: [email protected] Prof. Felix Dapare Dakora Research Development and Technology Promotion Cape Peninsula University of Technology, Room 2.8 Admin. Bldg. Keizersgracht, P.O. 652, Cape Town 8000, South Africa Email: [email protected] Dr. Geremew Bultosa Department of Food Science and Post harvest Technology Haramaya University Personal Box 22, Haramaya University Campus Dire Dawa, Ethiopia Email: [email protected] Dr. José Eduardo Garcia Londrina State University Brazil Email: [email protected] Prof. Nirbhay Kumar Malaria Research Institute Department of Molecular Microbiology and Immunology Johns Hopkins Bloomberg School of Public Health E5144, 615 N. Wolfe Street Baltimore, MD 21205 Email: [email protected] Prof. M. A. Awal Department of Anatomy and Histplogy, Bangladesh Agricultural University, Mymensingh-2202, Bangladesh Email: [email protected] Prof. Christian Zwieb Department of Molecular Biology University of Texas Health Science Center at Tyler 11937 US Highway 271 Tyler, Texas 75708-3154 USA Email: [email protected] Prof. Danilo López-Hernández Instituto de Zoología Tropical, Facultad de Ciencias, Universidad Central de Venezuela. Institute of Research for the Development (IRD), Montpellier, France Email: [email protected] Prof. Donald Arthur Cowan Department of Biotechnology,

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University of the Western Cape Bellville 7535 Cape Town, South Africa Email: [email protected] Dr. Ekhaise Osaro Frederick University Of Benin, Faculty of Life Science Department of Microbiology P. M. B. 1154, Benin City, Edo State, Nigeria Email: [email protected] Dr. Luísa Maria de Sousa Mesquita Pereira IPATIMUP R. Dr. Roberto Frias, s/n 4200-465 Porto Portugal Email: [email protected] Dr. Min Lin Research Scientist & Adjunct professor Animal Diseases Research Institute Canadian Food Inspection Agency Ottawa, Ontario, Canada K2H 8P9 Email: [email protected] Prof. Nobuyoshi Shimizu Department of Molecular Biology, Center for Genomic Medicine Keio University School of Medicine, 35 Shinanomachi, Shinjuku-ku Tokyo 160-8582, Japan Email: [email protected] Dr. Adewunmi Babatunde Idowu Department of Biological Sciences University of Agriculture Abia Abia State, Nigeria Email: [email protected] Dr. Yifan Dai Associate Director of Research Revivicor Inc. 100 Technology Drive, Suite 414 Pittsburgh, PA 15219 USA Email: [email protected] Dr. Zhongming Zhao Department of Psychiatry, PO Box 980126, Virginia Commonwealth University School of Medicine, Richmond, VA 23298-0126, USA Email: [email protected] Prof. Giuseppe Novelli Human Genetics, Department of Biopathology, Tor Vergata University, Rome, Italy Email: [email protected] Dr. Moji Mohammadi 402-28 Upper Canada Drive Toronto, ON, M2P 1R9 (416) 512-7795 Canada Email: [email protected] Prof. Jean-Marc Sabatier Directeur de Recherche Laboratoire ERT-62

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Ingénierie des Peptides à Visée Thérapeutique, Université de la Méditerranée-Ambrilia Biopharma inc., Faculté de Médecine Nord, Bd Pierre Dramard, 13916, Marseille cédex 20. France Email: [email protected] [email protected] Dr. Fabian Hoti PneumoCarr Project Department of Vaccines National Public Health Institute www.pneumocarr.org Finland Email: [email protected] Prof. Irina-Draga Caruntu Department of Histology Gr. T. Popa University of Medicine and Pharmacy 16, Universitatii Street, Iasi, Romania Email: [email protected] Dr. Dieudonné Nwaga Soil Microbiology Laboratory, Biotechnology Center. PO Box 812, Plant Biology Department, University of Yaoundé I, Yaoundé, Cameroon Email: [email protected] Dr. Gerardo Armando Aguado-Santacruz Biotechnology CINVESTAV-Unidad Irapuato Departamento Biotecnología Km 9.6 Libramiento norte Carretera Irapuato-León Irapuato, Guanajuato 36500 Mexico Email: [email protected] [email protected] Dr. Abdolkaim H. Chehregani Department of Biology Faculty of Science Bu-Ali Sina University Hamedan, Iran Email: [email protected] Dr. Abir Adel Saad Molecular oncology Department of Biotechnology Institute of graduate Studies and Research Alexandria University, Egypt Email: [email protected] Dr. Azizul Baten Department of Statistics Shah Jalal University of Science and Technology Sylhet-3114, Bangladesh Email: [email protected] Dr. Bayden R. Wood Australian Synchrotron Program Research Fellow and Monash Synchrotron Research Fellow Centre for Biospectroscopy School of Chemistry Monash University Wellington Rd. Clayton, 3800 Victoria,

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Australia Email: [email protected] Dr. G. Reza Balali Molecular Mycology and Plant Pthology Department of Biology University of Isfahan Isfahan Iran Email: [email protected] Dr. Beatrice Kilel P.O Box 1413 Manassas, VA 20108 USA Email: [email protected] Dr. Gabor L. Lövei Department of Integrated Pest Management Danish Institute of Agricultural Sciences Flakkebjerg Research Centre DK-4200 Slagelse Denmark Email: [email protected] Prof. H. Sunny Sun Institute of Molecular Medicine National Cheng Kung University Medical College 1 University road Tainan 70101, Taiwan Email: [email protected] Prof. Ima Nirwana Soelaiman Department of Pharmacology Faculty of Medicine Universiti Kebangsaan Malaysia Jalan Raja Muda Abdul Aziz 50300 Kuala Lumpur, Malaysia Email: [email protected] Prof. Tunde Ogunsanwo Faculty of Science, Olabisi Onabanjo University, Ago-Iwoye. Nigeria Email: [email protected] Dr. Evans C. Egwim Federal Polytechnic, Bida Science Laboratory Technology Department, PMB 55, Bida, Niger State, Nigeria Email: [email protected] Prof. George N. Goulielmos Medical School, University of Crete Voutes, 715 00 Heraklion, Crete, Greece Email: [email protected] Dr. Uttam Krishna Cadila Pharmaceuticals limited , India 1389, Tarsad Road, Dholka, Dist: Ahmedabad, Gujarat, India Email: [email protected] [email protected] Prof. Mohamed Attia El-Tayeb Ibrahim Botany Department, Faculty of Science at Qena, South Valley University, Qena 83523, Egypt

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Email: [email protected] Dr. Nelson K. Ojijo Olang’o Department of Food Science & Technology, JKUAT P. O. Box 62000, 00200, Nairobi, Kenya Email: [email protected] [email protected] Dr. Pablo Marco Veras Peixoto University of New York NYU College of Dentistry 345 E. 24th Street, New York, NY 10010 USA Email: [email protected], [email protected] Prof. T E Cloete University of Pretoria Department of Microbiology and Plant Pathology, University of Pretoria, Pretoria, South Africa Email: [email protected] Prof. Djamel Saidi Laboratoire de Physiologie de la Nutrition et de Sécurité Alimentaire Département de Biologie, Faculté des Sciences, Université d’Oran, 31000 - Algérie Algeria Email: [email protected] [email protected] Dr. Tomohide Uno Department of Biofunctional chemistry, Faculty of Agriculture Nada-ku, Kobe., Hyogo, 657-8501, Japan Email: [email protected] Dr. Ulises Urzúa Faculty of Medicine, University of Chile Independencia 1027, Santiago, Chile Email: [email protected] Dr. Aritua Valentine National Agricultural Biotechnology Center, Kawanda Agricultural Research Institute (KARI) P.O. Box, 7065, Kampala, Uganda Email: [email protected] [email protected] Prof. Yee-Joo Tan Institute of Molecular and Cell Biology 61 Biopolis Drive, Proteos, Singapore 138673 Singapore Email: [email protected] Prof. Viroj Wiwanitkit Department of Laboratory Medicine, Faculty of Medicine, Chulalongkorn University, Bangkok Thailand Email: [email protected] Dr. Thomas Silou Universit of Brazzaville BP 389 Congo

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Email: [email protected] Prof. Burtram Clinton Fielding University of the Western Cape Western Cape, South Africa Email: [email protected] Dr. Brnčić (Brncic) Mladen Faculty of Food Technology and Biotechnology, Pierottijeva 6, 10000 Zagreb, Croatia. Email: [email protected] Dr. Meltem Sesli College of Tobacco Expertise, Turkish Republic, Celal Bayar University 45210, Akhisar, Manisa, Turkey. E-Mail : [email protected] Dr. Idress Hamad Attitalla Omar El-Mukhtar University, Faculty of Science, Botany Department, El-Beida, Libya. Email: [email protected] Dr. LINGA R. GUTHA Washington State University at Prosser, 24106 N Bunn Road, Prosser WA 99350-8694. Email: [email protected] Dr.YU JUNG KIM Department of Chemistry and Biochemistry California State University, San Bernardino 5500 University Parkway San Bernardino, CA 92407 Email: [email protected] Dr Helal Ragab Moussa Bahnay, Al-bagour, Menoufia, Egypt. Email: [email protected] Dr VIPUL GOHEL Flat No. 403, Alankar Apartment, Sector 56, Gurgaon-122 002, India. Email: [email protected] Dr. Sang-Han Lee Department of Food Science & Biotechnology, Kyungpook National University Daegu 702-701, Korea. Email: [email protected] Dr. Bhaskar Dutta DoD Biotechnology High Performance Computing Software Applications Institute (BHSAI) U.S. Army Medical Research and Materiel Command 2405 Whittier Drive Frederick, MD 21702 Email: [email protected] Dr. Muhammad Akram Faculty of Eastern Medicine and Surgery, Hamdard Al-Majeed College of Eastern Medicine,

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Hamdard University, Karachi. Email: [email protected] Dr. M.MURUGANANDAM Departtment of Biotechnology St. Michael College of Engineering & Technology, Kalayarkoil, India. Email: [email protected] Dr. Gökhan Aydin Suleyman Demirel University, Atabey Vocational School, Isparta-Türkiye, Email: [email protected] Dr. Rajib Roychowdhury Centre for Biotechnology (CBT), Visva Bharati, West-Bengal, India. Email: [email protected]. (Go to Alphabetical listing)

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