Applied Mechanics and Materials Vol. 372

Abstract: Cellulose and hemicelluloses are the main building block of plant cell wall and are known as a natural polymer that usually used in the industries. Cellulose and hemicelluloses could be used as a feedstock for second generation biofuel production where it is subjected to hydrolysis into sugar after which it can be converted into bioethanol through fermentation process. In this study, the matured banana pseudo-stem is used as the source of hydrolyzing sugar from natural material. The objective of this research is to study the effects of different chemical pretreatments (sodium hydroxide, mixture of sodium hydroxide and hydrogen peroxide, sulphuric acid, mixture of sulphuric acid and hydrogen peroxide) and hydrolysis time (1-5 hours) on the sugar yield from banana pseudo-stem. Results showed that, after 3 hours hydrolysis most of the sugars from all chemical pretreatments reduced gradually. Analysis of sugar contents from acid hydrolysis process using High Pressure Liquid Chromatography (HPLC) showed that all the samples contained glucose, xylose, and arabinose where the highest glucose (16.02 mg/L) obtained from fiber treated with mixture of 1.0 M sulphuric acid and hydrogen peroxide. In addition, both highest xylose (64.23 mg/L) and arabinose (45.78 mg/L) are obtained from fiber treated with 0.5 M sodium hydroxide.

Abstract: High demand for wooden materials and rises in agricultural areas and forest fires increased the importance of composite particleboard instead of using solid woods. Particleboards are among the most popular materials used in interior and exterior applications. The objective of this study was to examine the physical and mechanical properties of phenol formaldehyde particleboard made from oil palm trunk (OPT) with 11% resin content. Two different board thicknesses were use; 12mm and 16mm. The particle size use in this study was 2mm and 1mm. Phenol formaldehyde (PF) was used as the binder. The result showed that modulus of rupture and modulus of elasticity were perform better at 16mm board thickness with 1.0mm particle size and meet the standard. The internal bonding strength was parallel with bending strength.

Abstract: Superconducting materials are a new kind of high-end technology materials mainly used in the fields of cutting-edge technology and military. However, the superiority of its various aspects is becoming familiar and understood gradually which steps this new material into all areas of the society. In the spirit of "people-oriented" principle, the purpose of every progress in science and technology or in any other field of social development is to accomplish people's all-round development, therefore, new technologies and new materials can always be integrated quickly into our daily life, in which they are improved and developed continuously. Family life is the most important element of people's daily life; therefore, given their superior properties, the wide application of superconducting materials to design household products is an inevitable trend in the future.

Abstract: This study reports inorganic nanoparticles modified molecular beacons as fluorescent DNA biosensors. MBs were modified by using CdTe quantum dots as energy donors and 4-(4'-(dimethylamino) phenylazo) benzoic acid, black hole quencher 1 and Au nanoparticles as energy acceptors, respectively. CdTe quantum dots were linked to molecular beacons when 1-ethyl-3-(3-dimethylaminopropyl) carbodi-imide hydrochloride was added. The fluorescence intensity of the modified molecular beacons decreased tremendously compared to the fluorescence intensity of CdTe quantum dots, which indicated that the fluorescence resonance energy transfer occurred between the donors and acceptors. The results indicated that this type of molecular beacons has high specificity and can be used to distinguish complementary DNA and its mutants.

Abstract: Fluorescent DNA probes based on the fluorescence resonance energy transfer (FRET) were presented in this paper when AuNPs were as the energy acceptors and CdTe quantum dots and CdTe/SiO2 core/shell nanoparticles were as the energy acceptors, respectively. The DNA probes were prepared when energy donors and acceptors were conjugated with two single-stranded complementary oligonucleotides and hybridized with each other and the fluorescent intensity of probes could be decreased. The quenching efficiency of DNA probe was about 67 % when CdTe QDs were as the energy donors, while that of DNA probe was about 75 % when CdTe/SiO2 fluorescent core/shell nanoparticles were as the energy acceptors, which indicated that CdTe/SiO2 core/shell nanoparticles were suitable donors compared with CdTe QDs in DNA probe field.

Abstract: In the present work, we employed low-energy ball milling in dry and wet conditions to synthesize Al-MWCNT composites with homogeneous distribution of reinforcing phases. Dry ball milling easily resulted in the collapse of MWCNTs as well as a cold welding of constituent particles. Wet milling, on the other hand, induced a homogeneous distribution of MWCNTs and matrix phase. However, the oxidation of aluminum which results in a poor sinterability, was a major problem in wet milling. The optimum content of MWCNT in the composites was 0.5 and 1 wt% for dry and wet milling, respectively.

Abstract: This paper describes the growth of Zn_xCd_1-xO nanorods (NRs) by a single step electrodeposition process. Thin films of polycrystalline nature with cadmium and zinc concentration changing from 10% - 90% were electrodeposited onto ITO conductive glass substrates. XRD analysis confirms a hexagonal wurtzite structure having grain size 57.2 nm. From the FESEM analysis, the synthesized Zn_xCd_1-xO nanorods have uniform hexagonal crystallographic planes, and their diameters are about 100 nm. Remarkably, the ultra-violet (UV) near-band-edge (NBE) emission was red-shifted from 2.75 eV to 3.02 eV due to the direct modulation of band gap caused by Zn/Cd substitution, revealed by UV visible spectroscopy. Finally, ZnCdO thin film deposited on ITO glass substrate is used as one electrode in photovoltaic cells to produce energy by absorbing the energy from the sun, this single junction cells have been put forward as a potential low-cost alternative to the widely used solar cells.

Abstract: In this study, polystyrene (PS) nanocomposites with TiO₂ and surface-modified TiO₂ nanoparticles were prepared by compression molding method. TiO₂ nanoparticles were modified by 3-(methacryloxy) propyl trimethoxysilane (MPS). The resulting nanocomposite thick films were compared with pure polystyrene. It was found that MPS-modified TiO₂ nanoparticles were better dispersed in PS matrix due to their hydrophobic characteristics. The addition of small amount of TiO₂ nanoparticles could greatly decrease the optical bandgap of PS from 4.0 eV in pure PS to less than 3.0 eV in PS-TiO₂ nanocomposite. The effects of surface modification and UVC irradiation on the physical properties and the degradation of nanocomposites were investigated.

Abstract: A core-hollow shell composite composed of a nickel (Ni) nanoparticle core encapsulated in a hollow silica shell (Ni@SiO₂) was prepared by using a nanocrystalline salt of nickel tris-hydrazine complex, which acted as not only a nickel source but also a solid template to produce the core-hollow shell structure. Structural characterizations using TEM and N₂ adsorption-desorption measurements of the thus-obtained Ni@SiO₂ powder revealed that it was composed of a Ni nanoparticle core of ca. 4.0 nm in diameter and a rectangular-shaped hollow silica shell with a micropore (ca. 0.5 nm in diameter) system.

Abstract: The purpose of this work was to study the wettability of single-walled carbon nanotube (SWCNTs) and molten 96.5Sn-3.0Ag-0.5Cu (SAC305) lead-free solder alloy. The SWCNTs was coated with silver (Ag) by using an electroless plating method in order to enhance its wettability. The wetting behavior of molten SAC305 alloy on three different substrates, alumina, un-coated SWCNTs and Ag-coated SWCNTs was investigated by employing a modified sessile drop technique. The wetting angle between the molten SAC305 and the three substrates was measured at temperature range of 250-550 °C. The average wetting angles between the molten SAC305 and the alumina, the un-coated SWCNTs and the Ag-coated SWCNTs substrates were 130.7±1.3°, 128.4±4.2° and 120.1±3.5°, respectively. The wettabilty of the SWCNTs was improved by coating it with silver. The wetting angle of the Ag-coated SWCNTs was decreased approx. 9° compared to that of the un-coated. Increasing temperature has slightly affected on the wettability of SWCNTs and the molten SAC305.