Solar rechargeable battery—principle and materials

A brief survey of the historical development of a photoelectrochemical solar cell is given. The principle and future of solar chargeable battery is compared with a wet and a dry type photovoltaic cell. A solar chargeable battery, with or without a membrane and with an aqueous solution or with solid-state electrolytes is discussed. A new unique type of configuration “Sharon-Schottky” junction solar cell is described which can be used either as a charger for any secondary batteries or could be used for photoelectrolysis of water. All these configurations and their relative merits are discussed. A review on the various semiconductors and types of solar chargeable batteries is made. Finally, a conclusion is drawn for future direction of research for developing an economically viable photoelectrochemical (PEC) solar cell based on either the principle of a solar charger (to charge a Ni---Cd battery or lead—acid battery) and/or solar chargeable battery with or without without a membrane. Some new innovative ideas for the preparation of materials is discussed. The entire discussion is geared towards answering a relevant question: what has gone wrong to result in the stagnation and failure in commercialization of a PEC based solar cell?

Transmembrane domains participate in functions of integral membrane proteins

Integral membrane proteins have one or more transmembrane a-helical domains and carry out a variety of functions such as enzyme catalysis, transport across membranes, transducing signals as receptors of hormones and growth factors, and energy transfer in ATP synthesis. These transmembrane domains are not mere structural units anchoring the protein to the lipid bilayer but seem to-contribute in the overall activity. Recent findings in support of this are described using some typical examples-LDL receptor, growth factor receptor tyrosine kinase, HMG-CoA reductase, F-0-ATPase and adrenergic receptors. The trends in research indicate that these transmembrane domains participate in a variety of ways such as a linker, a transducer or an exchanger in the overall functions of these proteins in transfer of materials, energy and signals.

Self-Assembly and Catalytic Activity of Metal Nanoparticles Immobilized in Polymer Membrane Prepared via Layer-by-Layer Approach

Densely packed nanoparticles distributed in a stable and robust thin film is a highly preferred system for utilizing the various applications of nanoparticles. Here, we report covalent bond mediated layer-by-layer (LbL) self-assembled thin films of nanoparticles embedded in polymer membrane. Polymer with complementary functional group is utilized for fabrication of thin film via covalent bonding. UV-visible spectroscopy, atomic force microscopy (AFM) and scanning electron microscopy (SEM) were used to monitor the growth of LbL thin film. Subsequently, the composite thin film is used for catalysis of an organic electron transfer reaction of p-nitrophenol to p-aminophenol by sodium borohydride. The catalytic activity of these composite films is assayed multiple times, proving its applicability as a catalyst. The kinetic data obtained by monitoring reduction of p-nitrophenol suggest that the reaction rates are directly related to the sizes of the nanoparticle and porosity of the membrane.

Role of outer membrane exopolymers of Acidithiobacillus ferrooxidans in adsorption of cells onto pyrite and chalcopyrite

Bacterial surface polymers play a major role in the adhesion of bacterial cells to solid surfaces. Lipopolysaccharides (LPS) are essential constituents of the cell walls of almost all Gram-negative bacteria. This paper reports the results of the investigations on the role of outer membrane exopolymers (LPS) of the chemolithotroph, Acidithiobacillus ferrooxidans, in adsorption of the cells onto pyrite and chalcopyrite. Optimization of EDTA treatment for removal of LPS from cell surface and the surface characterization of EDTA-treated cells are outlined. There was no change in cell morphology or loss in cell motility upon treatment with upto 0.04 mM EDTA for 1 h. Partial removal of LPS by EDTA treatment resulted in reduced adsorption of the cells on both pyrite and chalcopyrite. The protein profile of the EDTA-extractable fraction showed presence of certain outer membrane proteins indicating that EDTA treatment results in temporary gaps in the outer membrane. Also, specificity towards pyrite compared to chalcopyrite that was exhibited by untreated cells was lost when their exopolymer layers were stripped off, which could be attributed to the role of outer membrane proteins in the mineral-specificity exhibited by the bacteria. (C) 2013 Elsevier B.V. All rights reserved.

Biogenic nanosilver incorporated reverse osmosis membrane for antibacterial and antifungal activities against selected pathogenic strains: An enhanced eco-friendly water disinfection approach

Reverse osmosis (RO) membranes have been used extensively in water desalination plants, waste water treatment in industries, agricultural farms and drinking water production applications. The objective of this work is to impart antibacterial and antifungal activities to commercially available RO membrane used in water purification systems by incorporating biogenic silver nanoparticles (AgNPs) synthesized using Rosa indica wichuriana hybrid leaf extract. The morphology and surface topography of uncoated and AgNPs-coated RO membrane were studied using Scanning Electron Microscopy (SEM) and Atomic Force Microscopy (AFM). Elemental composition of the AgNPs-coated RO membrane was analyzed by energy-dispersive X-ray spectroscopy (EDAX). The functional groups were identified by Fourier Transform Infrared spectroscopy (FT-IR). Hydrophilicity of the uncoated and AgNPs-coated RO membrane was analyzed using water contact angle measurements. The thermal properties were studied by thermogravimetric analysis (TGA). The AgNPs incorporated RO membrane exhibited good antibacterial and antifungal activities against pathogenic bacterial strains such as E. coli, S. aureus, M. luteus, K. pneumoniae, and P. aeruginosa and fungal strains such as Candida tropicalis, C. krusei, C. glabrata, and C. albicans.

Ni Nano-particle Encapsulated in Hollow Carbon Sphere Electrocatalyst in Polymer Electrolyte Membrane Water Electrolyzer

The present study evaluates the synthesis by solvo-thermal method and electrocatalytic activity of nickel nano-particles encapsulated in hollow carbon sphere, in hydrogen and oxygen evolution reaction in PEM water electrolyzer. The XRD patterns have ascertained the formation of nickel metal with different planes in face centered cubic (fcc) and hexagonal closed pack (hcp) form. SEM and TEM images have confirmed the nickel nano-particles with diameter of 10-50 nm inside the 0.2 mu m sized hollow carbon spheres. The BET surface area values gradually decreased with greater encapsulation of nickel; although the electrochemical active surface area (ECSA) values have been calculated as quite higher. It confirms the well dispersion of nickel in the materials and induces their electrocatalytic performance through the active surface sites. The cyclic voltammetric studies have evaluated hydrogen desorption peaks as five times more intense in nickel encapsulated materials, in comparison to the pure hollow carbon spheres. The anodic peak current density value has reached the highest level of 1.9 A cm(-2) for HCSNi10, which gradually decreases with lesser amount of nickel in the electrocatalysts. These electrocatalysts have been proved electrochemically stable during their usage for 48 h long duration under potentiostatic condition. (C) 2015 Elsevier Ltd. All rights reserved.

Studies on elastic coupling parameters of fracture modes in orthotropic materials

The characterisation of cracks is usually done using the well known three basic fracture modes, namely opening, shearing and tearing modes. In isotropic materials these modes are uncoupled and provide a convenient way to define the fracture parameters. It is well known that these fracture modes are coupled in anisotropic materials. In the case of orthotropic materials also, coupling exists between the fracture modes, unless the crack plane coincides with one of the axes of orthotropy. The strength of coupling depends upon the orientation of the axes of orthotropy with respect to the crack plane and so the energy release rate components associated with each of the modes vary with crack orientation. The variation, of these energy release rate components with the crack orientation with respect to orthotropic axes, is analyzed in this paper. Results indicate that in addition to the orthotropic planes there exists other planes with reference to which fracture modes are uncoupled.

Synthesis and vesicle formation from hybrid bolaphile/amphiphile ion-pairs. Evidence of membrane property modulation by molecular design

Four new hybrid (bolaphile/amphiphile) ion-pairs were synthesized. Electron microscopy indicated that each of these forms bilayer membranes upon dispersion in aqueous media. Membrane properties have also been examined by differential scanning calorimetry, microcalorimetry, temperature-dependent fluorescence anisotropy measurements, and UV-vis spectroscopy. The T-m values for the vesicular 1, 2, 3, 4, and 5 were 38, 12, 85, 31.3, and 41.6 degrees C, respectively. Interestingly the T-m values for 1 and 3 were found to depend on their concentration. The entrapment of small solute and the release capability have also been examined to demonstrate that these bilayers form enclosed vesicles. X-ray diffraction of the cast films has been performed to understand the nature and the thickness of these membrane organizations. The membrane widths ranged from 33 to 47 Angstrom. Finally, the above observations have been analyzed in light of the results obtained from molecular modeling studies. Thus we have demonstrated that membrane properties can be modulated by simple structural changes at the amphiphile level. It was shown that by judicious incorporation of central, isomeric, disubstituted aromatic units as structural anchors into different bolaphiles, one can modulate the properties of the resulting vesicles.

An Investigation of Friction During Friction Stir Welding of Metallic Materials

The technique of friction stir welding (FSW) puts effective use frictional heat for the purpose of joining metallic materials. In this research article, we present and discuss an experimental method to determine the coefficient of friction during FSW. The experiments were conducted to study the interaction between the FSW tool (a die steel) and the base metal (a high strength aluminum alloy) at various contact pressures (13MPa, 26MPa, and 39MPa) and rotation speeds (200rpm, 600rpm, 1000rpm, and 1400rpm). The experimental results, the microstructure, and the process temperature reveal the experimental setup to be capable of simulating the conditions during FSW. The coefficient of friction was found to vary from 0.15 to 1.4, and the temperature increased to as high as 450C. The coefficient of friction was found to increase with temperature. There exists a critical temperature at which point a steep increase in the coefficient of friction was observed. The critical temperature decreases from 250C at a contact pressure of 26MPa to 200C at contact pressure of 34MPa. Below the critical temperature at a specific contact pressure the maximum coefficient of friction is 0.6, and above the critical temperature it reaches a value as high as 1.4. The steep increase in the coefficient of friction is found to be due to the seizure phenomenon and the contact condition during FSW between the tool and the workpiece (base metal) is found to be sticking.

Einstein Relation in n-Channel Inversion Layers of Nonlinear Optical, Optoelectronic and Related Materials: Simplified Theory, Relative Comparison and Suggestion for an Experimental Determination

In this paper, we study the Einstein relation for the diffusivity to mobility ratio (DMR) in n-channel inversion layers of non-linear optical materials on the basis of a newly formulated electron dispersion relation by considering their special properties within the frame work of k.p formalism. The results for the n-channel inversion layers of III-V, ternary and quaternary materials form a special case of our generalized analysis. The DMR for n-channel inversion layers of II-VI, IV-VI and stressed materials has been investigated by formulating the respective 2D electron dispersion laws. It has been found, taking n-channel inversion layers of CdGeAs2, Cd(3)AS(2), InAs, InSb, Hg1-xCdxTe, In1-xGaxAsyP1-y lattice matched to InP, CdS, PbTe, PbSnTe, Pb1-xSnxSe and stressed InSb as examples, that the DMR increases with the increasing surface electric field with different numerical values and the nature of the variations are totally band structure dependent. The well-known expression of the DMR for wide gap materials has been obtained as a special case under certain limiting conditions and this compatibility is an indirect test for our generalized formalism. Besides, an experimental method of determining the 2D DMR for n-channel inversion layers having arbitrary dispersion laws has been suggested.

Use of microwaves for the synthesis and processing of materials

An overview of the synthesis of materials under microwave irradiation has been presented based on the work performed recently. A variety of reactions such as direct combination, carbothermal reduction, carbidation and nitridation have been described. Examples of microwave preparation of glasses are also presented. Great advantages of fast, clean and reduced reaction temperature of microwave methods are emphasized. The example of ZrO2-CeO2 ceramics has been used show the extraordinarily fast and effective sintering which occurs in microwave irradiation.

In search of inorganic nonlinear optical materials for second harmonic generation

In a search for inorganic oxide materials showing second-order nonlinear optical (NLO) susceptibility, we investigated several berates, silicates, and a phosphate containing trans-connected MO6, octahedral chains or MO5 square pyramids, where, M = d(0): Ti(IV), Nb(V), or Ta(V), Our investigations identified two new NLO structures: batisite, Na2Ba(TiO)(2)Si4O12, containing trans-connected TiO5 octahedral chains, and fresnoite, Ba2TiOSi2O7, containing square-pyramidal TiO5. Investigation of two other materials containing square-pyramidal TiO5 viz,, Cs2TiOP2O7 and Na4Ti2Si8O22. 4H(2)O, revealed that isolated TiO5, square pyramids alone do not cause a second harmonic generation (SHG) response; rather, the orientation of TiO5 units to produce -Ti-O-Ti-O- chains with alternating long and short Ti-O distances in the fresnoite structure is most likely the origin of a strong SHG response in fresnoite,

Nanocrystalline Janus films of inorganic materials prepared at the liquid-liquid interface

The interface between toluene and water has been employed to prepare ultrathin Janus nanocrystalline films of metal oxides, metal chalcogenides and gold, wherein the surface on the organic-side is hydrophobic and the aqueous-side is hydrophilic. We have changed the nature of the metal precursor or capping agent in the organic layer to increase the hydrophobicity. The strategy employed for this purpose is to increase the length of the alkane chain in the precursor or use a perfluroalkane derivative as precursor or as a capping agent. The hydrophobicity and hydrophilicity of the Janus films have been determined by contact angle measurements. The morphology of hydrophobic and hydrophilic sides of the film have been examined by field emission scanning electron microscopy.

Analysis Of Curved Laminated Beams Of Bimodulus Composite-Materials

Composite materials exhibiting different moduli in tension and in compression, commonly called as bimodular composites are being used in many engineering fields. A finite element analysis is carried out for small deflection static behavior of laminated curved beams of bi modulus materials for both solid and hollow circular cross-sections using an iterative procedure. The finite element has 16 d.o.f. and uses the displacement field in terms of first order Hermite in terpolation polynomials. The neutral surface, i.e. the locus of points having zero axial strain is found to vary drastically depending on the loading, lay up schemes and radius of curvature. As il lustrations, plots of the cross-sections of the ruled neutral-surface are presented for some of the investigated cases. Using this element a few problems of curved laminated beams of bimodulus materials are solved for both solid and hollow circular cross-sections.

Co-assembly of a Nafion-Mesoporous Zirconium Phosphate Composite Membrane for PEM Fuel Cells

Synthesis of mesoporous zirconium phosphate (MZP) by co-assembly of a tri-block copolymer, namely pluronic-F127, as a structure-directing agent, and a mixture of zirconium butoxide and phosphorous trichloride as inorganic precursors is reported. MZP with a specific surface area of 84 m(2) g(-1) average pore diameter of about 17 nm and pore volume of 0.35 cm(3) g(-1) has been prepared, and characterised by X-ray diffraction (XRD) and transmission electron microscopy. Nafion-MZP composite membrane is obtained by employing MZP as a surface-functionalised solid-super-acid-proton-conducting medium as well as all inorganic filler with high affinity to absorb water and fast proton-transport across the electrolyte membrane even under low relative humidity (RH) conditions. The composite membranes have been evaluated in H-2/O-2 polymer electrolyte fuel cells (PEFCs) at varying RH values between 18 and 100%; a peak power density of 355 mW cm(-2) at a load current density of 1,100 mA cm(-2) is achieved with the PEFC employing Nafion-MZP composite membrane while operating at optimum temperature (70 degrees C) under 18% RH and ambient pressure. On operating the PEFC employing Nafion-MZP membrane electrolyte with hydrogen and air feeds at ambient pressure and a RH value of 18%, a peak power density of 285 mW cm(-2) at the optimum temperature (60 degrees C) is achieved. In contrast, operating under identical conditions, a peak power density of only similar to 170 mW cm(-2) is achieved with the PEFC employing Nafion-1135 membrane electrolyte.