Direct synthesis of copper faujasite

Copper containing faujasite has been successfully prepared for the first time using a direct synthesis method. Faujasite type zeolite can be prepared in the presence of copper species by tuning the synthesis conditions. Ammonium hydroxide was used to form a copper complex that was later mixed with the reacting gel. Sodium is required to obtain copper faujasite. The complete elimination of sodium ions from the starting gel produces amorphous material. Crystallization took place at 358 K for 11 days. Crystallization temperature of 373 K produces ANA type zeolite as an impurity. Increasing by two times the amount of copper complex added to the reacting gel increases the crystallization time of Cu-FAU from 11 to 20 days (the crystallization rate decreases). The copper containing faujasite obtained was characterized by XRD, FESEM, EDX, EPR, FT-IR, TPR, and BET. According to the XRD pattern only FAU type zeolite was obtained. According to TPR experiments, the reduction temperature for Cu²⁺ ions present in Cu-FAU prepared by direct synthesis was 70 K more than for Cu-FAU prepared by ion-exchange. This difference can be due to the different location of the copper ions in the supercages or in the sodalite cages of the faujasite.     

Surface integrity study of WEDM with various wire electrodes: experiments and analysis

Abstract

Wire electrical discharge machining (WEDM) is always significant for its high-precision machining. However, due to the generation of high discharge energy during machining, machined surfaces are often got distorted. These might be upgraded by choosing the correct tool with proper machining condition. The effects of the electrode materials and process parameters on different responses of WEDM like average surface roughness, recast layer thickness, and surface morphology are systematically examined here to enhance the knowledge of WEDM and its correlation with electrode property. The experiments have been carried out on one of the expensive steel namely Maraging steel 300 due to its applicability in tooling and aerospace industries. Plain brass wire, zinc-coated brass wire (ZCB), and silver-coated brass (SCB) wires are used as a tool electrode for analysis. Comparative experimental studies prove that among BW, ZCB, and SCB, the overall performance of SCB is commendable owing to the high-quality surface considering control parameters in low discharge energy level. However, the second-best performance is shown by ZCB.     

Synthesis and characterization of iron oxide nanoparticles by solvothermal method

In the present work iron oxide nanoparticles have been synthesized by alkaline solvo thermal method using anhydrous ferric chloride, sodium hydroxide, polyethylene glycol and cetyl trimethyl ammonium bromide and characterized by X-ray diffraction (XRD), Fourier Transform Infrared Spectroscopy (FTIR), Field Emission Scanning Electron Microscopy (FESEM), Energy-dispersive X-ray Spectroscopy (EDX) and Thermal Gravimetric Analysis (TGA). XRD indicated that the product is a mixture of different phases of iron oxide viz. gamma-Fe₂O₃ (maghemite, tetragonal), Fe₂O₃ (maghemite, cubic), Fe₃O₄ (magnetite, cubic) and ?-Fe₂O₃(epsilon iron oxide). FESEM studies indicated that size of the particles is observed in the range of about 19.8 nm to 48 nm. EDX spectral analysis reveals the presence of carbon, oxygen, iron in the synthesized nanoparticles. The FTIR spectra indicated absorption bands due to O-H stretching, C-O bending, N-H stretching and bending, C-H stretching and Fe-O stretching vibrations. TGA curve represented weight loss of around 3.0446 % in the sample at temperature of about 180°C due to the elimination of the water molecules absorbed by the nanoparticles from the atmosphere.     

Heat induced voltage generation in electrochemical cell containing zinc oxide nanoparticles

The quest for alternative energy sources has stimulated interest in several new materials. Using an aqueous suspension of zinc oxide nanoparticles in specially-designed electrochemical cells we have observed significant voltage (maximum 498.0 mV) and storage capacity (∼60 h) upon thermal excitation. Voltage increased gradually with increasing temperature. The cells exhibited reasonable energy conversion efficiency (maximum 1.05%). Moreover, increases in efficiency and storage duration were observed with the insertion of a planar lipid membrane (PLM) within the electrochemical cell, since the hydrophobic barrier of the lipid membrane hindered back recombination of the charges produced by thermal excitation. The novelty of the cells lies in the fact that voltage was generated by utilizing the heat energy of solar radiation, as opposed to the light quanta of the solar influx used in conventional photovoltaic cells.     

Hydrogen Sulfide Oxidation by Sulfide Quinone Oxidoreductase

Hydrogen sulfide (H₂S) is an environmental toxin and a heritage of ancient microbial metabolism that has stimulated new interest following its discovery as a neuromodulator. While many physiological responses have been attributed to low H₂S levels, higher levels inhibit complex IV in the electron transport chain. To prevent respiratory poisoning, a dedicated set of enzymes that make up the mitochondrial sulfide oxidation pathway exists to clear H₂S. The committed step in this pathway is catalyzed by sulfide quinone oxidoreductase (SQOR), which couples sulfide oxidation to coenzyme Q₁₀ reduction in the electron transport chain. The SQOR reaction prevents H₂S accumulation and generates highly reactive persulfide species as products; these can be further oxidized or can modify cysteine residues in proteins by persulfidation. Here, we review the kinetic and structural characteristics of human SQOR, and how its unconventional redox cofactor configuration and substrate promiscuity lead to sulfide clearance and potentially expand the signaling potential of H₂S. This dual role of SQOR makes it a promising target for H₂S-based therapeutics.     

Parthenium sp. as a plant biomass for the production of alkalitolerant xylanase from mutant Penicillium oxalicum SAUE-3.510 in submerged fermentation

The use of congress grass (Parthenium sp.) and water hyacinth (Eichhornia crassipes) as low cost raw materials for xylanase production from mutant Penicillium oxalicum SAU_E-3.510 in submerged fermentation was investigated. For development of mutant from wild type P. oxalicum SA-8 ITCC 6024, a strategy of mixed mutagenesis was followed using UV-irradiation and ethidium bromide, which had resulted into 1.87 fold increases in the activity of the enzyme. For enzyme production, the fungus was cultivated in mineral medium containing congress grass as carbon source. Considerably higher levels of production (475.2 ± 6.0 IU ml^?1) were achieved in media containing congress grass, although it was slightly less than that was obtained (488.5 ± 6.5 IU ml^?1) in presence of commercial oat spelt xylan. This fact confirms the feasibility of using this low cost non-food resource as an alternative carbon source to save costs of the enzyme production process. Maximum xylanase activity was reported at 55 °C with its stability at 80 °C for 2 h. The highest activity of xylanase at pH 9.0 and its stability at similar pH for 24 h denote the alkalitolerant nature of enzyme.     

Antimicrobial efficacy and biocompatibility study of copper nanoparticle adsorbed mullite aggregates

A mullite based antimicrobial ceramic composite has been developed by simple adsorption of copper nano particle suspension. The physico-chemical properties of samples were characterized by different instruments which showed that the composite is well crystalline with homogeneous distribution of copper nanoparticles on the surface. Antimicrobial study was performed by plate count technique which showed > 99% mortality for all the bacterial species studied after 24 h of incubation. Minimum inhibitory concentration (MIC) values determined by batch culture process showed considerably low values (in terms of copper content) indicating that mullite matrix plays a role in enhancing the antimicrobial efficacy of the composite. Biocompatibility studies on human cancer cell lines indicated that the composite had negligible toxicity below 100 μg/mL of Cu content. Thus the composite can be suitable for developing antimicrobial ceramic wares and therapeutic purposes like treatment of variety of microbial infections.     

Nanocrystalline Mullite Synthesis at a Low Temperature: Effect of Copper Ions

Nanocrystalline mullite with grain sizes in the range of 13–30 nm has been prepared by the sol–gel route at a temperature as low as 600°C with the incorporation of copper ions as copper sulfate. Characterization of the copper-doped mullite was performed by DTA–TG, X-ray diffraction (XRD), FESEM, and FTIR spectroscopy.     

Making sense of randomness: Implicit encoding as a basis for judgment.

People attempting to generate random sequences usually produce more alternations than expected by chance. They also judge overalternating sequences as maximally random. In this article, the authors review findings, implications, and explanatory mechanisms concerning subjective randomness. The authors next present the general approach of the mathematical theory of complexity, which identifies the length of the shortest program for reproducing a sequence with its degree of randomness. They describe 3 experiments, based on mean group responses, indicating that the perceived randomness of a sequence is better predicted by various measures of its encoding difficulty than by its objective randomness. These results seem to imply that in accordance with the complexity view, judging the extent of a sequence's randomness is based on an attempt to mentally encode it. The experience of randomness may result when this attempt fails. (PsycINFO Database Record (c) 2011 APA, all rights reserved)     

Efficiency of a dye-sensitized photoelectrochemical device using thionine and triturated zinc oxide at different potency

A new and novel material, triturated zinc oxide nanoparticles, which is eco-friendly, easily available, low in cost, has been used here for the first time for enhancement of photovoltage generation and efficiency of a dye-sensitized photoelectrochemical device. This material when diluted and strongly agitated, together termed as potentized, is used as nanomedicine for centuries. This study using this material at two different potencies (6C and 30C) shows that addition of this material to thionine dye of concentration 0.85 μM enhances photovoltage generation significantly. The efficiency obtained with the latter is ~0.41%, whereas it is ~0.003% with dye only.