Journal of Material Sciences & Engineering

A number of physical and chemical method available for the production of silver nanoparticles however these methods are quite costly and make use of poisonous chemicals. Thus use of biological organism as bionanofactories offers a clean and cost effective alternative process for the fabrication of silver nanoparticles. Extracellular synthesis of silver nanocrystals from Fusarium oxysporum was accomplished. Data obtained from Ultra violet visible spectrometry was used to calculate the concentration of siver nanoparticles at optimum conditions. The optimum conditions where the concentration of silver nanoaprticles were maximum was found to be 20 g of fungal biomass incubated at 40°C at pH 8.0 using substrate concentration of 2 mM.

Graphene oxide was synthesized by using modified Hummers method and also Graphene-NiO nanocomposite prepared by hydrothermal method with the use of graphene oxide solution, Ni(NO3)2•6H2O and urea as raw materials. The synthesized nanocomposite was characterized by the XRD, Raman, SEM, TGA and energy dispersive spectrometer analysis. The results demonstrate that NiO nano particles uniformly covered on the surface of the graphene layer and Raman spectroscopy states that well formation of the Graphene-NiO Nano composite. CV curves of Graphene-NiO electrodes at different scan rates conveys that capacitance characteristic is very different from that of traditional electric double-layer capacitance in which the shape is normally an ideal rectangular shape. Therefore, cyclic voltammetry analysis is the evidence of these materials are having the ability of supercapacitor electrode material properties. TGA Analysis is used for the estimation of how much of graphene is exist in the Graphene-NiO nanocomposite.

The now physically founded exponent 3/2 that governs the relation of normal force to depth3/2 in conical/pyramidal indentation is a physically founded (FN = k h3/2). Strictly linear plots obtain non-iterated penetration resistance k (mN/ μm3/2) as slope, initial effects (including tip rounding), adhesion energy, and phase transitions with their transformation energy and activation energy. The reason for the failing of the Sneddon theory, claiming wrong exponent 2 (as do ABAQUS or ANSYS finite element simulations) is their neglect of long-range effects by shearing. Previous undue trials to rationalize the non-occurrence of exponent 2 are polynomial fittings and "best or variable exponent" iterations for curve fittings that lose all unique information from the loading curve. Also ISO 14577 unloading hardness HISO and reduced elastic modulus Er-ISO lack physical reality. They are redefined to physical dimensions as new indentation parameters Hphys and Er-phys. For the first time physically sound indentation hardness Hphys is obtained without iterations solely from loading curves. Also all mechanical indentation parameters relying on Sneddon's exponent 2 are unphysical. They require redefinition with new dimensions. This applies also to visco-elastic-plastic parameters in a recent NIST tutorial. The present ISO-standards create dilemma with physics. But the risk from using wrong mechanical parameters against physics is dangerous, subject to change.

Composite materials are widely used in structural mechanics as they can withstand high loads; although after a while, they can present relative strain due to these loadings. In the present work, it is implemented digital image correlation using one laser-beam and the speckles created by its reflection to describe the mechanical behavior of fiber-reinforced composites submitted under compression test. Composites were tested in two set of arrays: the first was done with fibers orientated parallel to the load and the second was done with fibers randomly orientated, as it is known that the stress-strain evolution change according to the orientation of the fibers. Our method allows us to evaluate the heterogeneous strain evolution observed during the tests. Validity of optical strain-measurements is assessed against the results of an universal testing machine, a good correlation was found by comparing the results.

Composite-hydroxide-mediated (CHM) approach was used to synthesize NiO nanocrystals. The proposed method makes use of molten composite hydroxides; providing reaction media and lower the process temperature. Processing temperature and reaction time are the two potential parameters to control the growth of a nanomaterial. The method was used at temperatures in the range of 180-250°C and formation of the nanomaterial was monitored using XRD, SEM, EDX, FTIR, and UV-visible spectroscopy. The produced nanomaterial was purely polycrystalline with an average crystallite size in the range of 23.71-36.92 nm. Method suggested formation of pyramid shaped NiO nanocrystals in the temperature range 220-250°C. Evidence on the elemental composition, purity, and chemical bonding were obtained from EDX and FTIR analysis respectively. Estimation on direct bandgap was made from the optical analysis and found to be in the range 4.0-4.8 eV. The method is attractive and seems a cost effective route for the growth of transition metal oxides for research purpose. For further efficacy, the approach can be examined for other technologically significant nanostructures.

In this paper we studied weapons had found in archaeological finds in the Iberian Peninsula pre-Roman times, in which have been observed the presence of magnetite patinas. The novelty of the study is the presence of silver wires with these magnetite patinas and what technology was used to it.

Polymer composites have been thoroughly explored for future electromagnetic interference (EMI) applications owing to their unique combination of electrical, mechanical, and optical properties. The composition, morphology, and surface characteristics of the filler material play critical roles in regulating the composite activity. We studied the formation, synthesis and EM attenuation properties of nickel zinc ferrite (NZF) + Polycaprolactone (PCL) microcomposites that were prepared via the conventional mixed oxide (CMO) technique. Compared with other preparation routes, CMO may provide the advantages of a simple process and the ability for mass production and controlled product formation. A rectangular waveguide connected to a vector network analyser coaxial cable was employed to measure the scattering parameters [S] for use in determining the attenuation values of NZF+PCL substrates for a variety of NZF% values. Measurement tests showed a simultaneous increment in the attenuation value with the filler percentage. NZF+PCL samples of 1-mm thickness were able to attenuate microwave frequencies by up to ~3.33 dB, where the highest attenuation magnitude of 8.599 dB over a large area was attributed to the 12.5% NZF filler content at 12 GHz. Thus, a low transmission of waves resulted from the high shielding effectiveness (SE) values that showed a maximum 6.86 dB EM interference. Scanning electron microscopy (SEM) was utilized to analyse the average particle size (1.45 μm) of the filler powder.

Aral problem, as the largest environmental disaster the world has acquired acute. This crisis affects the interests of all countries in Central Asia, which is becoming a concern of the world community. In this context, innovative research on the quality and safety of animal products in environmentally disadvantaged areas of the Kazakhstan part of the Aral sea region, is very relevant. One purpose was to conduct scientific research on the presence of heavy metals in the dairy products produced in the farms of the Aral and Kazalinsk areas of the Kyzylorda region of Kazakhstan. It was found that the quality of dairy products compared with the standard rate only slightly reduced and priority objectives for environmental health in the region, are the realization of projects for the system water allocation pools, as well as regulatory measures zones of the Syrdarya river, Recover and preserve the natural background of vegetation and disturbed the balance of the land.

This study reports on the synthesis of zinc oxide (ZnO) nanostructures and examines the performance of polymer nanocomposites fabricated using ZnO dispersed in polymer host matrices. The polymer matrix used was an epoxy based thermosetting polymer known as Diglycidyl Ether of Bisphenol-A(DGEBA). Zinc oxide nano particles were prepared by precipitation method using Poly Vinyl Alcohol as the surface modifier. It was characterized using Scanning Electron Microscopy (SEM) and X-ray Diffraction (XRD). And the average particle size has been found to be 25 nm. The main objective of this study is to investigate the simultaneous effect of the additive ZnO nanoparticles and curing agent on the curing kinetics, mechanical and morphological properties of Diglycidyl ether of bisphenol-A system. The mechanical properties of epoxy resin based on diglycidyl ether of bisphenol-A and Zinc Oxide were also investigated and improved mechanical properties were obtained for epoxy resin with 2% filler concentration.

Iron ores are used in blast furnace for the production of pig iron; AGBAJA Iron ore has an estimated reserve of over I billion metric tonnes. Unfortunately, this large reserve cannot be utilized for the production of pig iron due to its high sulphur contents. This work studied the reduction of sulphur content of AGBAJA iron ore. Acid leaching methods were used to reduce sulphur contents of the ore. Sulphuric acid of different concentrations were used at various leaching times, acid concentrations and particle sizes. Atomic Absorption Spectrophotometer, X-ray fluorescence spectrophotometer, Digital muffle furnace and Absorbance-concentration technique were used for experimentation and chemical analysis. The reduction of the sulphur content of AGBAJA Iron Ore using Acid leaching process experiments were carried out at the National Metallurgical Development Centre (NMDC), Jos in Plateau State of Nigeria. Sulphur is one of the main harmful elements in ferrous metallurgy and it affects the quality of iron and steel produced. At present, Nigeria has some large iron ore deposits including AGBAJA which bear tremendous iron ore with high sulphur content of 0.12%. Central composite design technique was applied to obtain optimum conditions of the processes. Surface response plots were obtained. The percentage degrees of reduction of sulphur content of AGBAJA Iron ore were found to increase with increase in acid concentration and leaching time and a decrease in particle size for the three acids. The experimental results for percentage removal of sulphur are 85.56% the optimum % removal of sulphur is 89.66%. The result of this work has shown that AGBAJA Iron Ore if properly processed can be used in our metallurgical plants and also can be exported since sulphur contents of the ore have been reduced drastically.

An analytical and numerical solution for the one dimensional of heat conduction in a slab exposed to different temperature at both ends is presented. The distribution of heat throughout the transient direction obeys to functionally graded (FG) temperature based on Dirichlet boundary conditions. The variation of functionally graded temperature can be described by any form of continuous function. In this case, where the external heat fluxes are not directly definite based on the Dirichlet or mixed boundary conditions, the fluxes that concluded over the slab faces are free to vary until the equilibrium condition is reached. By numerically solving the resulting heat-conduction equation, the distribution of temperature which vary with time through the slab is obtained. The obtained analytical results are presented graphically and the influence of the gradient variation of the temperature on shape formed with changed time is investigated.

Long fiber reinforced thermoplastic (LFT) composites have recently found increasing use in transportation, military and aerospace applications and become well established as high volume and low cost materials with high specific modulus and strength, superior damage tolerance, and excellent fracture toughness. This study is conducted to evaluate the performance of long fiber reinforced thermoplastic composite at elevated high temperature. Long carbon fiber reinforced polyarylamide (CF/PAA) composites containing 20 wt% and 30 wt% carbon fibers are used and processed using extrusion compression molding. Flexural and tensile samples are tested at three temperatures, room temperature, medium temperature (MD 65°C) and glass transition temperature (TG 80°C). Samples in both longitudinal and transverse directions are prepared to show the effect of the orientation on mechanical properties at different temperatures. The testing results show that as temperature increases, both of the flexural and tensile properties of the CF/PAA decrease as expected. Both of the flexural and tensile modulus reduce more dramatically than the flexural and tensile strength, indicating that the temperature has more pronounced effect on modulus than strength. The transversely oriented samples generally show larger reduction in properties than the longitudinally oriented samples. Temperature significantly affects flexural strength at the elevated temperature section between MD and TG temperature.

Possibilities of plasma chemical deposition of а-Si1-xGex:H (x=0 ÷ 1) films undoped and doped with PH3 or B2H6 have been analyzed from the viewpoint of their application in p-i-n structures of solar cell. The optical properties are considered, and the amount of hydrogen contained in those films is determined. The film properties are found to strongly depend on the film composition and the hydrogenation level. The number of hydrogen atoms in the films is varied by changing the gas mixture composition, and IR absorption in а-Si:H and а-Ge:H films is measured. The а-Si:H and а-Si0,88Ge1,2:H films were used to fabricate three-layer solar with an element area of 13 sm2 and an efficiency (ξ) of 9.5%.

In order to better understand the solubility properties of polyalkane, polyether and polysilicone materials, which are critical to the foaming behavior of shampoo and shaving creams, GROMACS molecular dynamics NVT simulations were performed using the OPLS-AA force field to determine the time-average number of hydrogen bonds in solutions of water co-solvated with methanol, ethanol, isopropanol, dimethyl ketone and acetyl methyl carbinol.

CdSe thin films were deposited on a glass substrate by using electron beam evaporation technique. The as deposited films were annealed from 100ºC to 300°C with an increment of 100°C. Morphological, structural and optical characterization of the films was carried out by using scanning electron microscope (SEM), X-ray diffraction (XRD), ultraviolet-visible (UV-Vis) spectroscopy; and Fourier transform infrared spectroscopy. The X-ray diffraction pattern that the film has a cubic phase with preferred orientation (100), the grain size was found to be in the range of 29-46 nm. SEM results reveal that film grains are polycrystalline in nature covered the whole surface of the substrate.

The CuTl-1223 superconducting samples, doping the Sr atom at Ba site, have been synthesized at 860oC pressure. The charge reservoir layer (CRL) of Cu0.5Tl0.5-1223 superconductor is modified by doping Sr atom. The decrease in c-axis length which is most probably due to smaller size of Sr atom as compared to Ba. The substitution of Sr atom at Ba is confirmed by the Fourier Transform Infrared Spectroscopy (FTIR). The critical temperatures i.e., Tc(R=0). Tconset are increased with the Sr content which shows that superconducting magnitude enhanced. The excess conductivity analysis has been done using Aslamazov-Larkin and Lawrance-Donaich models. The crossover temperatures i.e., TCR-3D=TG, T3D-2D and T2D-SWF and c-axis coherence length ξc(0) are slanted to lower values. Moreover, the inter-plane coupling (J) increases due to decrease in c-axis length. From fluctuations induced conductivity, it is found that there is an inverse relationship between critical temperatures and coherence length.

A structural model of metal-rich amorphous alloys is proposed. This model differs from the known models of the atomic structure of amorphous metal-rich alloys consisting of transition metal-early transition metal components or of transition metal-metalloid components. The atomic structures of these kinds of alloys were studied by means of synchrotron high energy X-ray diffraction. The results obtained are presented in the form of radial distribution functions suggesting that the atomic structures of amorphous transition metal-rich alloys consist of clusters with chemically disordered and structurally distorted bcc cells, irrespective of the crystal structure of the corresponding pure metallic elements.