பொருள் அறிவியல் & பொறியியல் இதழ்

Effect of aqueous electrolytes (KOH, KCl, CH3 COONa and NH4 Cl) on electrochemical behaviour of Supercapacitor was studied by cyclic voltammetry, cyclic stability, and electrochemical impedance analysis. The results show that among all aqueous electrolytes investigated, KOH revealed good supercapacitive behaviour and exhibited 675Fgm-1 specific capacitance, 86% of cyclic stability, 100% columbic efficiency and 8Ω equivalent series resistance ESR.

The objective of the present research is to analyze the structure, behavior and applicability of the integrated biosystems, through the study of the ancestral, current and potential uses of the sucker palms - Socratea Exhorriza and chonta - Iriartea Deltoidea; And how its ecosystem functioning provides us with environmental goods and services; Which until now have not been thoroughly reviewed and therefore many of its properties are unknown. It is for this reason that this research tries to demonstrate that there are tools that make it possible to formulate plans, programs or projects of sustainable use that allow the biosystem to maintain itself as the ecosystem. It is understood by integrated biosystems such as those that link two or more biological systems to transform organic waste into value-added products, through the use of processes involving microorganisms, major organisms, animals and plants. One of the processes becomes the raw material for the start of the next or the following processes (Rodríguez, et al.). "Biosystems are semi-open chemical chemosystems (or chemical reactors), which take from their surroundings the matter and energy they employ, which synthesize all their other components and reproduce" (Bunge). They are made up of elements among which are living beings organized at different hierarchical levels. For example, genetic systems, organ systems, parasite systems, plant systems, among others, where intermediate levels can be observed between individual systems and population systems or communities (Jaramillo). These constitutive elements play a fundamental role in the functioning of systems and therefore of biosystems, such as: Inorganic substances, organic compounds, climatic elements, producers, consumers, disintegrators. The study will be carried out through seven stages: The first one refers to the bioconstruction and use of wood, the second to the use of biomass, the third, the fauna refuge, the fourth, the entomological analysis of species found in Cellulose; The fifth, to edible and medicinal uses, the sixth to the interaction of microorganisms in the soil; And the seventh and last to the proposal of normative tools and recommended uses.

In the present work, laser induced shock wave on different materials was studied, the used materials is [Paramagnetic metal (Stainless steel 304) and Ferro magnetic metals (Iron)]; immersed in some media (air and water) to study the media effect on its properties. These materials are irradiated by using different laser intensities. Laser induced shock wave was achieved by employing Nd-YAG laser at wavelength 1064 nm. X-ray diffraction revealed shifting in diffracted angles of Fe toward higher angles due to phase transformation where in air transition from Austenite to Martensite while in water from Martensite to Martensite has smaller grain size because high generated temperature followed by quenched, the diffracted angle of S.S.304 metal shifted toward very little value due to twining effects where high stress and strain are produced.

The physics of industrial single-point force indentation hardness measurements (Vickers, Knoop, Brinell, Rockwell, Shore, Leeb, and others) is compared with the depth-sensing nano, micro, and macro instrumental hardness technique that provides several further mechanical parameters, when using the correct force/depth curves exponent 3/2 on the depth of the loading curves. Only the latter reveal phase change onset with transition energy, and temperaturedependent activation energy, which provides important information for applications of all types of solids, but is not considered in the ISO or ASTM standards. Furthermore, the high-load one-point techniques leave the inevitably even stronger and more diverse consecutive phase-transformations undetected, so that the properties of pristine materials are not obtained. But materials are mostly not (continuously) applied under so high load, which must lead to severe misinterpretations. The dilemma of ISO or ASTM standards violating the basic energy law, the dimensional law, and denying the occurrence of phase changes under load is demonstrated with the physics of depth-sensing indentations. Transformation of iterated ISO-hardness and finite element simulated hardness to physical hardness is exemplified. The one-point techniques remain important for industry, but they must be complemented by physical hardness with detection of the phase transformation onset sequences for the reliability of their results. The elastic modulus EISO from unloading curves as hitherto unduly called "Young's" modulus has nothing in common with unidirectional Young's modulus according to Hook's law, because the skew tip faces collect contributions from all crystal faces including shear moduli, while iteration fit is to Young's modulus of a standard. Unphysical and also physically corrected multidirectional indentation moduli mixtures of mostly anisotropic materials and there from deduced mechanical parameters have no physical basis and none of these should be used any more. A possible solution of this dilemma might be the use of indentation-Ephys and bulk moduli K from hydrostatic compression measurements. The reasons for obeying physical laws in the mechanics of materials are stressed.

Polymer solar cells (PSCs) are emerging alternative candidates to the standard silicone technology for green and renewable energy generation owing to their flexibility and solution processability. Bulk heterojunction (BHJ) organic solar cells (OSCs) based on conjugated semiconducting polymers as donor (D) and fullerene derivatives as acceptor (A) offer large D/A interfacial area, which overcomes the short exciton diffusion length. Although, recent advances in narrow band gap semiconducting polymers have led to the improvement in power conversion efficiency of organic photovoltaics (OPVs) beyond 10%, inefficient charge separation and low carrier mobility as well as negligible photon harvesting in near-infrared (NIR) and/or infrared (IR) region of the solar spectrum have still remained as bottle neck for ultimate performance of OPVs. Most PSCs only absorb the UV-visible part of the solar spectrum, leading to the low light harvesting efficiency. Hence, solution processed photoactive materials comprising nanostructured semiconducting inorganic quantum dots (QDs) as sensitizer have attracted great attention to improve energy conversion efficiency of the OPVs. This is attributed to the outstanding optoelectronic properties of QDs such as band gap tunability, potential NIR photons harvesting and multi exciton generation (MEG). However, the main shortcoming of inorganic QDs based OSCs is randomly hopping charge transport among discrete QD particles, which can be tackled through hybridization with one dimensional (1D) electrically conductive nanostructured materials such as carbon nanotube (CNT). By this way, CNT particles would behave as support for anchoring the light harvesting semiconductor QDs, leading to the enhancement of the exciton dissociation and charge transport towards the corresponding electrodes. Recently, manufacturing PSCs co-sensitized by QD loaded CNT has been shown as a promising direction to maximize performance of the device. This article reviews the recent developments in enhancement of OPVs‟ performance by utilization of high efficient light harvesting QDs and/or their hybrid with 1D CNTs.

Generally the methods were used to characterize soil contamination include collecting samples of soil then analyzing them to recognize contaminates in the laboratory. Commonly, this method of characterizing the contamination of a soil system is the only one agreeable to regulatory societies. However, sample analysis in the lab faces important problems such as soils sampling is really time consuming and costly, sampling is not constant with time and the samples be able to contaminate through sampling and carrying to the lab. Thus several geophysical techniques have been developed which used the dissimilarity in the soil physical properties after soil contamination. Dielectric technique shows high conceivable for characterization diesel contaminated soil. Further use of this technique; rely upon the availability of information about the dielectric properties of the contaminated soil. In this study, the effects of induced by a diesel presence in an unsaturated soil, on the complex dielectric properties were sought. It has been shown experimentally that the diesel presence in an unsaturated soil is traduced by an increase of both dielectric constant and loss factor. A comparison with the existing results in this study and in the literature for saturated soils shows an opposite effect on the complex dielectric properties. The importance of the influence induced by the diesel on the dielectric properties of an unsaturated soil was noticed and compared to a saturated soil. On the basis of the theoretical dielectric mixture models, a justification to these opposite behaviors and their importance has been presented and various models for the two cases have been developed.

Hydrocarbon reservoir is a porous and permeable structure in underground that are placed natural accumulation hydrocarbons in a liquid or gas forms and they are isolated by non-permeable rocks from the surrounding environment. Petroleum industry has used a wide variety of methodologies for stimulating the reservoir fluids to obtain the maximum amount of production rate in the surface; this method entails CO2 injection by transporting to the preferred layers which had the most recovery factor over a period of 35 years. Besides, in terms of fractured reservoirs enhanced oil recovery of these formations were poorly considerable candidates due to the complexity of predicting the productivity of these reservoirs. Oil and injected fluids tend to produce oil through gaps or cracks in the matrix block and cannot be moved easily. The purpose of this research is to gradually increase the extent of recovery by injecting carbon dioxide, methane and water. PVT modules of Eclipse software were being used. By injecting carbon dioxide into the reservoir, Injected Gas due to its gravity drainage move through the fracture of block matrix.

Fiber-reinforced composites are essentially axial particulates embedded in fitting matrices. The primary objective of fiber-reinforced composites it to obtain materials with high strength in conjunction with higher elastic modulus. The strength elevation is however affected with applied load transiting from matrix to fibers, interfacial bonding between fiber-matrix, their relative alignment and nature of fiber scheming the overall material behaviors. The alignment of fibers may however be continuous or random depending on the end applications. The choice of the fiber reinforcement and its fitting matrix also depends on application requirements. In recent years, the advent of composite technology has led to the development of different fiber reinforced composite systems via varying manufacturing methodologies to obtain advanced material behaviors. Herein, we present a comparative account on various kinds of synthetic fibers and their significance as potential reinforcements with special emphasis on carbon fibers.

The main aim of this study is to test the feasibility of using composite membrane of nonwovens and Nanofibre for the pre-filtration treatment of reactive dye bath effluent from the textile industry. The results of ultraviolet spectrophotometer of filtered and non-filtered sample show that the cleaning efficiency of effluent water will be achieved in the range of 70-80%. Cleaning efficiency of the Nano-filter filter remains around 70%. But a composite nonwoven filter made up of polyester fibre needle punched nonwoven and Nano-fibre web; the cleaning efficiency can reach as high as 90%.

To understand the behaviour of materials for applications in solid state electronic devices, the materials are to be exposed to different stresses such as thermal, electrical, humidity, optical, nuclear radiations, pressure (static or dynamic) etc. to better understand their structural, morphology, conduction, optical and sensing properties. The Se85-xTe15Agxcompositions prepared from melt-quench technique were exposed to high pressure (0-10 GPa) and temperature (300-373 K). The results depict the change in resistivity with respect to pressure in forward as well as backward pressurization. These results depicts that there is very small change in resistivity with change in pressure and the change in resistivity with respect to pressure follows the same pattern, when the pressure is applied from atmospheric pressure to 10 GPa and vice versa. The results of resistivity change with the variation of Silver in the compositions are also reported in this study. Similar results are observed in case of resistivity change with respect to temperature. Some deviation is observed in the results which are well explained with average coordination number, fermi level change and crystallinity.

Soil samples were randomly collected from the dump-yard of Katsina steel rolling mill and were analyzed for the presence and concentrations of the carcinogenic heavy metals namely: Chromium (Cr), Arsenic (As), Cadmium (Cd), Cobalt (Co) and Lead (Pb) using flame atomic absorption spectrophotometry instrumental method. The obtained concentrations were used to estimate the excess lifetime cancer risk due to exposure from these metals using models provided by the United State Environmental protection Agency for the population ages. The total estimated excess lifetime cancer risk due to exposure from these heavy metals via ingestion, inhalation and dermal pathways was found to be in the range of 2.73E-04 to 9.23E-07 for children, 6.07E-07E-07 to 5.64E-02 for adults and were majorly contributed by Chromium (Cr). These range clearly indicated the existence of values far above the USEPA recommended threshold of 1.00E-06 and consequently indicating that there is high risk of lifetime cancer development in the inhabitants around the study area.