Mechanical property evaluation of an Al-2024 alloy subjected to HPT processing

An aluminum-copper alloy (Al-2024) was successfully subjected to high-pressure torsion (HPT) up to five turns at room temperature under an applied pressure of 6.0 GPa. The Al-2024 alloy is used as a fuselage structural material in the aerospace sector. Mechanical properties of the HPT-processed Al-2024 alloy were evaluated using the automated ball indentation technique. This test is based on multiple cycles of loading and unloading where a spherical indenter is used. After two and five turns of HPT, the Al-2024 alloy exhibited a UTS value of ~1014 MPa and ~1160 MPa respectively, at the edge of the samples. The microhardness was measured from edges to centers for all HPT samples. These results clearly demonstrate that processing by HPT gives a very significant increase in tensile properties and the microhardness values increase symmetrically from the centers to the edges. Following HPT, TEM examination of the five-turn HPT sample revealed the formation of high-angle grain boundaries and a large dislocation density with a reduced average grain size of ~80 nm. These results also demonstrate that high-pressure torsion is a processing tool for developing nanostructures in the Al-2024 alloy with enhanced mechanical propertie

Synthesis, spectral characterization, in-vitro microbiological evaluation and cytotoxic activities of novel macrocyclic bis hydrazone

A macrocyclic hydrazone Schiff base was synthesized by reacting 1,4-dicarbonyl phenyl dihydrazide with 2,6-diformyl-4-methyl phenol and a series of metal complexes with this new Schiff base were synthesized by reaction with Co(II), Ni(II) and Cu(II) metal salts. The Schiff base and its complexes have been characterized by elemental analyses, IR, 1H NMR, UV-vis, FAB mass, ESR spectra, fluorescence, thermal, magnetic and molar conductance data. The analytical data reveal that the Co(II), Ni(II) and Cu(II) complexes possess 2:1 metal-ligand ratios. All the complexes are non-electrolytes in DMF and DMSO due to their low molar conductance values. Infrared spectral data suggest that the hydrazone Schiff base behaves as a hexadentate ligand with NON NON donor sequence towards the metal ions. The ESR spectral data shows that the metal-ligand bond has considerable covalent character. The electrochemical behavior of the copper(II) complex was investigated by cyclic voltammetry. The Schiff base and its complexes have also been screened for their antibacterial (Escherichia coli, Staphylococcus aureus, Shigella dysentery, Micrococcus, Bacillus subtilis, Bacillus cereus and Pseudomonas aeruginosa) and antifungal activities (Aspergillus niger, Penicillium and Candida albicans) by MIC method. The brine shrimp bioassay was also carried out to study their in-vitro cytotoxic properties. © 2009 Elsevier Masson SAS. All rights reserved

BEST FROM WASTE

In our country, India, worshiping is the way of living and people offer various offerings to the deities which mainly consist of flowers, leaves, fruits, coconuts, clothes. out of which floral offerings are found in huge quantity. Thus, temple waste has a unique share of flower waste in the total waste. After fulfilling their purpose, flowers along with other waste, find their way into the garbage or are discarded either into some water bodies or left up on the open places as a waste causing various environmental problems. The majorly offered flowers in temples are rose, jasmine, marigold, chrysanthemum, hyacinth, hibiscus, etc. This floral waste can be utilized in different ways to produce valuable products and can thus help to save environment from pollution caused due to improper disposal of flower waste. Techniques like vermicomposting, composting, dyes extraction, extraction of essential oils, making of holy colors and bio-gas generation can be used. Moreover, this flower waste can also be used for making incense sticks besides using them for some art and craft techniques. Petals of different flowers can also be utilized for handmade papermaking by extracting the pulp or by mottling them into the readymade pulp. In this paper, we have reviewed the ways by which temple waste can be utilized and managed to get valuable products which will lead to a healthier and waste free environmen

A recent review on Nanoemulsion as a topical delivery system of antipsoriatic drugs

Psoriasis and psoriatic arthritis are a chronic skin disease of autoimmune system that is identified as patches of abnormal skin, affecting 2-5% of the world’s population. Psoriasis is an incurable lifetime disease which can be controlled and relieved through medication. Various approaches have been explored to treat the disease. Treatment of psoriasis includes topical therapy, systemic therapy and phototherapy. Topical therapy is the main psoriasis treatment. However, the conventional topical treatment such as gel and cream have low efficiency to  poor cosmetic and aesthetic appeal leading to poor patient compliance or adherence. Nanoemulsions are transparent or translucent dispersions, having the droplet size less than 100 nm with ultra-low interfacial tension, large o/w interfacial areas and long term physical stability recently, much attention has been paid to the application of Nano emulsion as drug delivery system. A small droplet size would enhance the drug delivery and penetration of a drug through the psoriasis skin layer. A good selection of oils and surfactants would enhance the transdermal treatment efficacy in psoriatic patient. Keywords: Nano emulsion topical drug delivery, psoriatic treatmen

Effect Of Annealing On Structure, Morphology, Electrical And Optical Properties Of Nanocrystalline TiO2 Thin Films

Semi-transparent and highly conducting nanostructured titanium oxide thin films have been prepared by sol-gel method. Thin films of TiO2 deposited on glass substrates using spin coating technique and the effect of annealing temperature (400 - 700 °C) on structural, microstructural, electrical and optical properties were studied. The X-ray diffraction and Atomic force microscopy measurements confirmed that the films grown by this technique have good crystalline tetragonal mixed anatase and rutile phase structure and homogeneous surface. The study also reveals that the rms value of thin film roughness increases from 7 to 19 nm. HRTEM image of TiO2 thin film (annealed at 700 °C) shows that a grain of about 50 - 60 nm in size is really aggregate of many small crystallites of around 10 - 15 nm. Electron diffraction pattern shows that the TiO2 films exhibited tetragonal structure. The surface morphology (SEM) of the TiO2 film showed that the nanoparticles are fine with an average grain size of about 50 - 60 nm. The optical band gap slightly decreases from 3.26 - 3.24 eV and the dc electrical conductivity was found in the range of 10-6 to 10-5(Ω·cm)-1 when the annealing temperature is changed from 400 to 700 °C. It is observed that TiO2 thin film annealed at 700 °C after deposition provide a smooth and flat texture suited for optoelectronic applications. When you are citing the document, use the following link http://essuir.sumdu.edu.ua/handle/123456789/967

Investigating the Temperature Effects on ZnO, TiO2, WO3 and HfO2 Based Resistive Random Access Memory (RRAM) Devices

In this paper, we report the effect of filament radius and filament resistivity on the ZnO, TiO2, WO3 and HfO2 based Resistive Random Access Memory (RRAM) devices. We resort to the thermal reaction model of RRAM for the present analysis. The results substantiate decrease in saturated temperature with increase in the radius and resistivity of filament for the investigated RRAM devices. Moreover, a sudden change in the saturated temperature at a lower value of filament radius and resistivity is observed as against the steady change at the medium and higher value of the filament radius and resistivity. Results confirm the dependence of saturated temperature on the filament size and resistivity in RRAM

High-precision calculations of van der Waals coefficients for heteronuclear alkali-metal dimers

Van der Waals coefficients for the heteronuclear alkali-metal dimers of Li, Na, K, Rb, Cs, and Fr are calculated using relativistic ab initio methods augmented by high-precision experimental data. We argue that the uncertainties in the coefficients are unlikely to exceed about 1%.Comment: 11 pages, 2 figs, graphicx.st

Investigating the Temperature Effects on ZnO, TiO2, WO3 and HfO2 Based Resistive Random Access Memory (RRAM) Devices

In this paper, we report the effect of filament radius and filament resistivity on the ZnO, TiO2, WO3 and HfO2 based Resistive Random Access Memory (RRAM) devices. We resort to the thermal reaction model of RRAM for the present analysis. The results substantiate decrease in saturated temperature with increase in the radius and resistivity of filament for the investigated RRAM devices. Moreover, a sudden change in the saturated temperature at a lower value of filament radius and resistivity is observed as against the steady change at the medium and higher value of the filament radius and resistivity. Results confirm the dependence of saturated temperature on the filament size and resistivity in RRAM

Preparation and Characterization of Metformin Hydrochloride — Compritol 888 ATO Solid Dispersion

Metformin hydrochloride (MET) sustained-release solid dispersions (SD) were prepared by the solvent evaporation and closed melt method, using compritol 888 ATO as the polymer with five different drug-carrier ratios. Characterization of solid dispersion was carried out by Fourier Transform Infrared (FTIR) spectroscopy, ultraviolet (UV) spectroscopy, Differential scanning calorimetry (DSC), X-ray powder diffraction (XRPD). The FTIR and UV studies suggested that no bond formation had occurred between the polymer and the drug. DSC and XPRD results ruled out any interaction or complex formation between the drug and the polymer. The formulated SD had acceptable physicochemical characters and SD with a 1 : 4 drug : Polymer ratio, which released the drug over an extended period of eight-to-ten hours. The data obtained from the in vitro release studies were fitted with various kinetic models and were found to follow the Korsmeyer-Peppas equation. The prepared SD showed good stability over the studied time period. The solvent evaporation method was found to be more helpful than the closed melt method, giving the sustained release action. The SD with a 1 : 4 ratio of drug to polymer, by the solvent evaporation method, was selected as the most effective candidate for the subsequent development of a well-timed, sustained-release dosage form of the drug