Advanced Materials Research Vol. 925

Abstract: Human population has always been advocated to use exosomatic energy, exist in abundance in Mother Nature. As of today world's population has reached to 7.1 billion, which will be exceeding 8.0 billion by 2050. To fulfill the energy demand of increasing population, world existing energy should be increased by >50% by 2050. The question is do we have enough energy resources to meet the future energy demand Secondly, the use of reserved gas, oil, coal and other carbon-based energy sources would continue to emitgreenhouse gases which are estimated to warm up the world by 2°C by 2020, raising the sea level which will dwindle the world cultivable land. This paradigm shift has called foreffective, sensitive and advanced technologies dealing with the production, harvesting, conversion and distribution of renewable energy to meet the future energy needs. This paper has highlighted the potential applications of carbon nanotube (CNT) based composites to harvest the unlimited solar energy into electrical, mechanical and other forms of useful energy for human benefits. The competitive performances of CNTs in solar cells would build multibillion dollar energy market using green chemistry principles, reducing green house emission and ensuring enough energy for the future generations.

Abstract: Nanocellulose promises to be a very versatile material having wide range of biomedical and biotechnological applications including tissue engineering, drug delivery, wound dressings, medical implants, food, cosmetics, paper and textiles. The current methods for the synthesis of nanocellulose involve harsh chemical treatments which are perpetually hazardous to human and environment. Catalytic synthesis of nanocellulose might be a green approach. Among the various types of catalyst, ionic liquids, which are composed of both cations and anions and have low or negligible vapor pressure, are particularly promising. Ionic liquids also exhibit a relatively wide electrochemically stable window, good electrical conductivity, high ionic mobility, a broad range of room temperature liquid compositions, selective dissolvability to many organic and inorganic materials, and excellent chemical and thermal stabilities. In contrast, zeolite catalysts have been used in petroleum refineries for the removal of sulfur. Zeolite catalysts are also important for the synthesis of bulk chemicals, fine and specialty chemicals, fuels and chemicals. Acidic and metal modified micro porous zeolite catalysts have been used in several commercial processes in petroleum industry, fuel components, abatement of exhaust gas emissions and biomass upgrading, pharmaceutical and fine chemical industries. Currently, zeolite catalysts are synthesized in powder form and to make them industrially useful, such catalysts have to be mixed with a binder and formulated in different shapes. This paper reviewed the introduction, preparation, synthesis and application of nanocellulose from lignocellulosic palm biomass.

Abstract: Oil palm is a major agricultural product in Malaysia and it covers approximately 5 million hectares of land. Palm tree biomass is a by-product of oil palm cultivation. Biomass is a complex structure composed of cellulose, hemicelluloses and lignin. Cellulose, which gives the mechanical properties to the natural fiber, is organized in micro-fibrils enclosed by the other two main components: hemicellulose and lignin. Cellulose microfibrils can be found as intertwined microfibrils in the cell wall (220 μm in diameter and 100 40,000 nm in length). Cellulose microfibrils are in turn exist in cellulose nanofibers having diameter of 550 nm and length several millimeters conformed by nanocrystalline domains and amorphous regions. Nanocellulose, which is a degradation product of cellulose, has recently come to public attention because of its great mechanical properties combined with low molecular weight, renewability and biodegradability. Another advantage of nanofibrillar cellulose is that their production does not interfere with the food chain, therefore, they can be considered as socially sustainable raw materials. However, before the nanocellulose can be fully utilized to fabricate smart and environmentally friendly new high-tech products. Most common applications of nanocellulose are for polymer composite, bioplastics, films, foams, gels, cosmetics, dimensionally stable thickener and emulsion, implant material, biodegradable tissue scaffold, suture, drug delivery vehicle, filter paper, speaker membrane, battery membrane, concrete, drilling muds & enhanced oil recovery, water treatment, etc. Several methods have been proposed for the extraction/preparations of nanocellulose which involve extensive chemical and mechanical treatments which are not environmentally friendly. This paper reviewed various methods along with their limitations for the controlled structure synthesis of functionalized nanocellulose from palm tree biomass. The green catalytic approaches are schematically outlined.

Abstract: Lignin is the second most abundant naturally occurring macromolecule found in plant cell-wall, vascular components and woody stems. It is the largest renewable source of aromatic biopolymer. However, lignin is recalcitrant to be broken down by most chemicals. This is because of its complicated heterogeneous molecular structure. However, lignin depolymerization has huge potentials for the synthesis of a number of useful chemicals, perfumes and pharmaceuticals and toiletries. The oxidation products of lignin are important precursors for pulp/paper and food industries, synthetic thin films. Vanillin, veratryl aldehyde and para-benzoquinone are the oxidation products of lignin. These chemicals are the precursors of optically active alcohol, ketone, violuric acid and benzaldehyde. However, the oxidation of biolignin has been remaining a challenging task. Green catalytic approaches might be an interesting solution for the selective depolymerization of lignin into various platform chemicals. Metal oxide/silica supported nanoporous gold has received strong attention as green catalyst for the transformation of various natural polymers. Mesoporous metal oxide/silica provide enlarged surfaces for the breakdown of C-C, C-H and C-OH bonds. This paper has reviewed various green catalytic approaches for the control depolymerization of biolignin into platform chemicals.

Abstract: Lignocellulosic biomass consists of three polymeric components, namely cellulose, hemicellulose and lignin. Lignin is an amorphous polymer made by three different phenolic compounds, namely guaiacyl alcohol (G), syringyl alcohol (S) and p-coumaryl alcohol (H). It is the main component of cell walls and is composed of a 3D randomized net linked to cellulose and hemicelluloses. It functions as a biological barrier and glue to retain linked hemicelluloses and celluloses. Lignin and lignin derived compounds have important applications in paper and pulp industry as well as barrier thin film industry. On the other hand, cellulose and hemicelluloses are important feed stocks for biofuel, specialty chemicals and bio-surfactants. Degradation of lignin is a key step for the production of biofuel from biomass resources. Lignin can be depolymerized with enzyme and metal based catalyst, and acid peroxidases. Enzymatic approaches are green but expensive and slow. Acid peroxidases are often harsh, non-specific, and environmentally unfriendly and destroys lignin, cellulose and hemicelluloses. Several types of metal catalysts have been proposed for the selective cleavage of lignin. For example, nanoNi (O) was prepared by reducing of NiCl₂ with NaBH₄ under ultrasonication, Fe₃O₄ (NiAlO)_x was prepared by calcination of Mg (Ni)-Al hydrotalcite with incorporation of Fe₃O₄ followed by reduction with hydrogen, and NiO nanosheets were synthesized by reduction of Ni (NO₃)₂ with urea using benzyl alcohol as a structure directing agent. These metal based catalysts demonstrated promising results by depolymerizing lignin under thermal ultrasonic conditions. This paper reviewed various catalysts, their synthesis processes and mechanistic actions for the pretreatment of palm tree biomass for the extraction of all three components, namely cellulose, hemicelluloses and lignin.

Abstract: The soil is considered the most abundant building material in the world and after the only local resource available to the engineer for his work. On the other hand, the inclusion of materials such as soil stabilizing agents allowed improving some of its properties (mainly strength, permeability), reducing costs and environmental effects. This research investigated the effect of Acrylic polymer addition on permeability to four types of fill soils from different areas in Anbar government by laboratory tests working (i.e. the addition of different percentage of Acrylic polymer 25%, 50%, 75%, and 90% from optimum moisture content (O.M.C).The addition of acrylic to the soils lead to significant decrease in soil permeability and this serves in improving the soil layers that are effect on stability of foundation and very necessary for sensitive structures such as hydraulic structures (reservoir dams, earth dams , ... etc.). Descriptive statistical analysis including mean comparison using Duncans Multiple Range Test (DMRT) was conducted using SPSS software.

Abstract: Nanostructured apatite has been widely used as a bone substitute material due to its close resemblance to human bone mineral. To further mimic biological apatites, multiple ions doped non-stoichiometric nanoapatite has been studied. A nanosized apatite (NAp-2) containing Mg (1.09 wt%), Na (0.15 wt%), K (0.008 wt%) and CO₃^2- (5.18 wt%) was synthesized by a wet precipitation technique. The presence of these ions in NAp-2 was detected using ICP. Broad diffraction peaks of XRD results indicated the presence of nanocrystalline phase pure NAp-2. The primary particle size of the resulted powder was ~ 20 nm, typical of bone crystal size, estimated using Scherrers equation. Based on CHN results, the NAp-2 powders showed a total loss of 51 and 78% of carbonate ions when heat-treated at 900°C in both CO₂ and air atmospheres, respectively. This indicates that the heat-treatment in CO₂ flux has reduced the carbonate ions lost from the NAp-2. A highly crystalline HA phase was formed in the ionic doped NAp-2 without secondary phases, indicating a thermal stability of this powder at 900°C in CO₂ and air atmospheres. Thus, this study demonstrated that a phase pure multiple ions doped nanoapatite was synthesized using a wet precipitation technique.

Abstract: In order to widen the application range of bioactive glass (BG), we prepared a bioactive glass as a composite matrix, strengthened by titania nanoparticles. The prepared composites had different amounts of both bioactive glass (49S) and titania in the weight percents of 1:3, 1:1 and 3:1, respectively. Bioactive glass sols (49S) in the system (SiO₂CaOP₂O₅) were prepared following the solgel technique, then a solution of 2 wt% methylcellulose was added and stirred at room temperature. Precalcinated TiO₂ nanopowder was dispersed in the sol and the prepared mixture was fired at 600 °C. The inhomogeneity problem in preparation of composite powder was overcome by using methylcellulose (MC) as a dispersant. The nanostructure composites were characterized using X-ray diffraction (XRD) and Fourier transforms infrared spectroscopy (FT-IR). The microstructure of the surfaces of the different composites was examined by scanning electron microanalysis (SEM) to verify the apatite formation. The results led us to the conclusion that the addition of MC reinforces the composites and increases the formation of an apatite layer in the presence of BG and titania content.

Abstract: Reactive Ion Etching (RIE) is an important process in fabrication of semiconductor devices. Design Of Experiment (DOE) has been used to study the effect of Reactive Ion Etch (RIE) towards surface morphology of aluminum bond pad. Important RIE factors involved in this experimental study are ratio of Tetrafluoromethane (CF₄), Argon gas flow, BIAS, and ICP power. Different combinations of these factors produces different results of surface morphologies which was obtained using Atomic Force Microscopic (AFM). Produced results shows that overall surface roughness of the pad is affected by RIE and DOE offers a better way to optimize the desired outcome.

Abstract: This paper presents the correlation between electroless process time, immersion gold process time and the bump height in electroless nickel immersion gold (ENIG). A certain bump height need to be achieved in order to create acceptable solder bumps for reflow process. The study was done using a full factorial design of experiment (DOE). The DOE matrix is made of two levels with two factors. Analysis was done by plotting the main effects plot for each factor. The results suggest that higher process time increases the plating rate where the temperature fixed at 100 °C. It can be concluded that electroless nickel time has more influence to the bump height compared to immersion gold time.