Ahmed Mohareb - Academia.edu (original) (raw)

Papers by Ahmed Mohareb

Alexandria Science Exchange Journal /Alexandria Science Exchange journal, Mar 30, 2024

This research aimed to assess the improvements in dimensional stability and resistance to wood de... more This research aimed to assess the improvements in dimensional stability and resistance to wood decay by treating the wood with a solution of glycerol-maleic anhydride mixture (GLY-MA) without a catalyst, at four concentrations (10%, 15%, 20%, and 25%), followed by heat treatment at 170 °C for 4 h. Four wood species were selected for property testing: two locally grown in Egypt, namely Tree of heaven (Ailanthus altissima, heartwood) and Cypress (Cupressus sempervirens, sapwood), and two imported species, European beech (Fagus sylvatica) and Norway spruce (Picea abies), both heartwood. The treatment conditions reported here proved the effectiveness in enhancing the stabilization against water absorption for all four wood species. All four concentrations improved dimensional stability, with the highest improvement observed with the 25% treatment for all wood species. Although the treatments had a slight effect on decreasing compressive strength and hardness, a clear significant difference was observed at a concentration of 25% compared to untreated samples. The hardness at a 25% concentration was 4434.7 N, 2440 N, 5220 N, and 1440 N for Tree of heaven, Cypress, Beech, and Spruce, respectively. Across all species studied, the use of the four concentrations demonstrated a shift in wood resistance against white rot and brown rot fungi from nonresistant to moderately resistant. Therefore, in terms of cost-effectiveness, it is recommended to use the low concentration, 10% to enhance decay resistance, as this concentration effectively achieves the desired outcome without the need for higher concentrations, in addition to being environmentally friendly.

Wood Science and Technology, May 22, 2010

In this study, the use of polyvinyl alcohol (PVA) as boron fixative agent was investigated. Two l... more In this study, the use of polyvinyl alcohol (PVA) as boron fixative agent was investigated. Two levels of PVA (2.5 and 4%) were evaluated with disodium octaborate tetrahydrate (DOT) at three concentrations (1, 2 and 4% boric acid equivalent (BAE)) using a double vacuum impregnation process on Scots pine sapwood specimens. Leaching was performed according to a laboratory leaching procedure.

European Journal of Wood and Wood Products, Oct 27, 2011

ABSTRACT Heat treatment is an effective method to improve biological resistance of low natural du... more ABSTRACT Heat treatment is an effective method to improve biological resistance of low natural durability wood species. The aim of this study was to enhance the decay resistance of Pinus patula, an African low natural durability softwood species, via wood thermal modification technique. Heat treatment was performed on wood specimens under inert conditions at different heat treatment intensities to reach mass losses of 5, 10 and 15%. Heat treated specimens were exposed to fungal decay using the brown rot fungus Poria placenta. The wood chemical and elemental composition was determined as well as extractives toxicity before and after wood thermal modification to understand the reasons of durability improvement. The treated specimens exhibited a significant increase in their durability against wood decay in line with the severity of the treatment. Wood holocellulose was found to be distinctly more sensitive to the heating process than the lignin constituent. In addition, obvious correlations were observed between weight losses recorded after fungal exposure and both holocellulose decrease and lignin ratio increase. The same correlations were observed with the elemental composition changes allowing using the observed differences for predicting of wood durability conferred by heat treatment. Furthermore, no significant differences were observed between the toxicity of Pinus patula wood extractives before and after its thermal modification.

41st Annual Meeting of the International Research Group on Wood Protection, Biarritz, France, 9-13 May 2010, 2010

ABSTRACT In this study, the use of polyvinyl alcohol (PVA) as boron fixative agent was investigat... more ABSTRACT In this study, the use of polyvinyl alcohol (PVA) as boron fixative agent was investigated. Two levels of PVA (2.5 and 4%) were evaluated with disodium octaborate tetrahydrate (DOT) at three concentrations (1, 2 and 4% boric acid equivalent (BAE)) using a double vacuum impregnation process on Scots pine sapwood specimens. Leaching was performed according to a laboratory leaching procedure. Boron analysis using atomic absorption spectrometer showed a significant reduction in boron leachability for the samples treated with both concentrations of PVA when compared to the stand-alone boron treatment leading to boron retentions capable of preventing wood biological degradations. Decay resistance of the leached specimens was evaluated using the brown rot fungus Poria placenta. Even if complete protection was not fully achieved, an improvement in decay resistance was observed for the samples treated with DOT in presence of PVA. This leak of efficacy was attributed to a decrease in the biological activity of the complexed boron against fungi. Durability of treated wood against termite attack, evaluated using Reticulitermes santonensis, indicated a significant enhancement for the samples treated in presence of the fixative agent compared to the pure boron treatment.

Journal of Polymers and The Environment, Jul 22, 2016

The urban solid waste problem has been one of the biggest environmental challenges these days. In... more The urban solid waste problem has been one of the biggest environmental challenges these days. In this context, developing biocomposites with improved performance by using various sources and wastes has been intensified in the last decades for economic and environmental points of view. In this study, physical behavior, fungal decay and termite attack tests were conducted in laboratory conditions to investigate the performance of composites developed from TetraPak and textile wastes. All the results were compared to standard wood products. The water swelling properties strongly decreased in the manufactured TetraPak composites when compared with the conventional particleboard panels. The fungal decay resistance tests revealed that the stand alone TetraPak based composites were not completely resistant to wooddecaying fungi. A significant amelioration in the decay durability was observed for the manufactured TetraPak composites compared to the standard wood samples. Durability classes were determined according to the criteria given in the European standard (CEN/TS15083-1). Interestingly, the data indicated that the increment of the wool waste proportion in the produced boards lead to a significant enhancement counter the test fungi. The results of termite screening test showed further considerable resistance for whole TetraPak based composites against termites when compared to traditional wood samples. Such panels could be an available alternative without any additives for wood based composite structures and it can be used in a wide range of applications.

International Biodeterioration & Biodegradation, Mar 1, 2010

Borates are well known for their ability to protect wood against fungal and insects attacks. Howe... more Borates are well known for their ability to protect wood against fungal and insects attacks. However, their use in outdoor applications is limited due to their high leachability from treated wood. In this study, monoglycerides were investigated as fixative agents to reduce boron depletion from Scots pine using a double vacuum impregnation process involving impregnation with disodium octaborate tetrahydrate (DOT) followed by a second impregnation with the fixative agent. Significant reduction in boron leachability in samples treated with monoglycerides was observed compared to the standalone boron treated specimens. Evaluation of decay resistance of treated blocks using the brown rot fungus Poria placenta indicated a slight increase of durability, while resistance to termites attacks was strongly improved as demonstrated by the low weight losses and the high termites mortality levels observed. Monoglycerides could therefore be valuable additives to reduce boron depletion for outdoor applications in which wood is exposed to natural leaching conditions.

Communications in agricultural and applied biological sciences, 2004

Polymer Degradation and Stability, 2010

Journal of Applied Biotechnology & Bioengineering

Al-Jabal Al-Akhdar region (Libya) has highest species diversity and having distinct environmental... more Al-Jabal Al-Akhdar region (Libya) has highest species diversity and having distinct environmental characteristics associated with evergreen forest along with the Mediterranean from the Atlas Mountains to the Levant, and it has an environment similar to other regions in Southern Europe such as Italy, the Greek islands and Turkey.1 The number of plant species reach up of 1100 species from the total of plant species in Libya (2000 species) with about 75 species of plants that grow only in AL-Jabal AL Akhdar and have been served for as basis of traditional medicinal systems for thousands of years.1–5 In addition, such plants produce a remarkable diverse array of over 5,00,000 low and high molecular mass natural products which are known as secondary metabolites, which can be used as an alternative form of health care as well as screening for active compounds that have significant effects against human and plant pathogens.2,6–8 Cupressus sempervirens; Juniperus phoenicea, Olea europaea and Pinus halepensis are a large species of trees which grew widely in temperate regions include Al-Jabal Al-Akhdar region, Libya and have been used in traditional medicine in many part of the world.1,9–13

The Natural Products Journal

Background: Plant extracts are important products in the world and have been widely used for isol... more Background: Plant extracts are important products in the world and have been widely used for isolation of important biologically active products. Because of their significant environmental impact, extensive research has been explored to determine the antimicrobial activity of plant extracts. Methods: Acetone extracts of the bark and leaf of Cupressus sempervirens and Juniperus phoenicea, collected from three different altitudes (125, 391, and 851 m high of sea level) at Al- Jabel Al-Akhdar area, Libya were obtained and analyzed by GC/MS. The antimicrobial activity of the extracts was further evaluated against plant bacteria Rhizobium radiobacter, Erwinia carotovora, Rhodococcus fascians and Ralstonia solanacearum and fungus Botrytis cinerea. Results: The impact of the altitude from the sea level on the quantity and chemical constituents of the extracts was investigated. The yield was largely dependent on tree species and the highest yield (6.50%) was obtained with C. sempervirens L ...

Alexandria Science Exchange Journal: An International Quarterly Journal of Science Agricultural Environments

In Egypt, Casuarina glauca and Eucalyptus camaldulensis are main common fast growing hardwood spe... more In Egypt, Casuarina glauca and Eucalyptus camaldulensis are main common fast growing hardwood species in plantations, which have a high potential for use in this country. In this study, thermal treatment process was used to improve the durability of these locally produced wood species as an effective mean in wood preservation. In this context, wood specimens were exposed to heat under inert atmosphere in laboratory conditions at temperature of 240°C with different durations to reach mass losses of 5, 10 and 15%. Fungal decay tests were conducted using the brown rot fungus Poria placenta and the white rot fungus Coriolus versicolor. The chemical composition of the wood and the elemental composition as well as the extractive toxicity before and after thermal modification of the wood were determined to understand the reasons for the improvement of the durability of the wood. Heat-modified wood specimens showed a significant increase in their durability against wood decomposition depending on the severity of the treatment. Wood holocellulose was found to be distinctly more sensitive to the heating process than lignin constituent did. In addition, the weight loss was increase by fungal decay and holocellulose was decreased however, the lignin ratio was increased. The results obtained in this work may provide valuable information as a way towards the use of heat treatment technology in wood preservation in Egypt.

Journal of Polymers and the Environment, 2016

Energies, 2016

The objective of the study was to analyze chemical structure of date palm (Phoenix dactylifera L.... more The objective of the study was to analyze chemical structure of date palm (Phoenix dactylifera L.) by employing ultimate, proximate and thermo-gravimetric techniques. Samples from different anatomical parts of date palm, namely trunk, frond base, frond midrib, leaflets, coir, fruit stem, date stone, and fruit empty bunches were considered for the experiments. Based on the findings in this work palm leaflet samples gave the highest amount of extractives content (32.9%), followed by date palm stone specimens with 31.5%. Cellulose content values of 32.8% and 47.5% were obtained for date palm stone and palm coir samples, respectively. Overall the hemicellulose contents of all samples were relatively similar to those of typical wood or non-wood lignocellulosic materials with the two exceptions of palm coir and palm leaflets. Both palm coir and palm leaflet specimens had 12.6% and 16.1% hemicellulose content. Volatile matter values of 74.3% and 87.5% were determined for leaflets and fruit empty bunch samples. The ash content of the samples ranged from 1.4% for date stone to 15.2% for palm leaflet samples. The thermal decomposition was completed below a temperature of 500˝C with an exception of those samples taken from palm leaflets. Taken together the data indicate that date palm stone and palm coir revealed could be more viable for renewable energy production than the other specimens considered in this work.

International Biodeterioration Biodegradation, Mar 1, 2010

Journal of Applied Polymer Science, 2015