Effect of Interfacial Microstructure of Adsorbed Poly(ethylene glycol) Monooleate on Steel Substrate on Sliding Friction in Oil in Water Emulsion

The concentration of a nonionic surfactant and water pH were varied in an oil-in-water emulsion to minimize the friction coefficient between a steel ball sliding on a steel flat. At a surfactant concentration near the CMC (critical micelle concentration) the oil droplet size was found to be minimum. In this paper we study the microstructure of the surfactant molecules self-assembled on the steel substrate in water to comment on the ability of the surfactant aggregate to attract and retain oil. We find that a near semicylindrical hemimiceller microstructure with hydrocarbon tails projecting into bulk water as obtained at CMC in near neutral water is best able to capture and retain oil in yielding a low coefficient of friction.

Caryophyllene-Rich Essential Oil of Didymocarpus tomentosa: Chemical Composition and Cytotoxic Activity

The essential oil from the leaves of Didymocarpus tomentosa was extracted by hydrodistillation and analyzed by GC/FID and GC/MS. Twenty five constituents amounting to 81.6% of the oil were identified. The leaf oil contained 78.7% sesquiterpenes and 2.9% monoterpenes. The leaf essential oil of D. tomentosa is a unique caryophyllene-rich natural source containing beta-caryophyllene, caryophyllene oxide, alpha-humulene and humulene oxide. The cytotoxic activity of the oil was determined by the BSLT using shrimp larva and the MTT assay using HeLa tumor cell line. The oil showed significant cytotoxic activity with LC50 and IC50 values of 12.26 and 11.4 mu g/mL, respectively. This is the first report on the chemical composition and cytotoxic activity of the essential oil of D. tomentosa.

Grafting of Dispersants on MoS2 Nanoparticles in Base Oil Lubrication of Steel

Solid lubricant nanoparticles in suspension in oil are good lubricating options for practical machinery. In this article, we select a range of dispersants, based on their polar moieties, to suspend 50-nm molybdenum disulfide particles in an industrial base oil. The suspension is used to lubricate a steel on steel sliding contact. A nitrogen-based polymeric dispersant (aminopropyl trimethoxy silane) with a free amine group and an oxygen-based polymeric dispersant (sorbital monooleate) when grafted on the particle charge the particle negatively and yield an agglomerate size which is almost the same as that of the original particle. Lubrication of the contact by these suspensions gives a coefficient of friction in the similar to 0.03 range. The grafting of these surfactants on the particle is shown here to be of a chemical nature and strong as the grafts survive mechanical shear stress in tribology. Such grafts are superior to those of other silane-based test surfactants which have weak functional groups. In the latter case, the particles bereft of strong grafts agglomerate easily in the lubricant and give a coefficient of friction in the 0.08-0.12 range. This article investigates the mechanism of frictional energy dissipation as influenced by the chemistry of the surfactant molecule.

AN EXPERIMENTAL STUDY ON EFFERVESCENT ATOMIZATION OF BIO-OIL FUELS

This paper presents the work on detailed characterization of effervescent spray of Jatropha and Pongamia pure plant oils. The spray characteristics of these biofuels are compared with those of diesel. Both macroscopic and microscopic spray characteristics at different injection pressures and gas-to-liquid ratio (GLR) have been studied. The particle/droplet imaging analysis (PDIA) technique along with direct imaging methods are used for the purpose of spray characterization. Due to their higher viscosity, pure plant oils showed poor atomization compared to diesel and a blend of diesel and pure plant oil at a given GLR. Pure plant oil sprays showed a lower spray cone angle when compared to diesel and blends at lower GLRs. However, the difference is not significant at higher GLRs. Droplet size measurements at 100 mm downstream of the exit orifice showed reduction in Sauter mean diameter (SMD) diameter with increase in GLR. A radial variation in the SMD is observed for the blend and pure plant oils. Pure oils showed a larger variation when compared to the blend. Spray unsteadiness has been characterized based on the image-to-image variation in the mean droplet diameter and fluctuations in the spray cone angle. Results showed that pure plant oil sprays are more unsteady at lower GLRs when compared to diesel and blend. A critical GLR is identified at which the spray becomes steady. The three regimes of spray operation, namely ``steady spray,'' ``pulsating spray,'' and ``spray and unbroken liquid jet'' are identified in the injection pressure-GLR parameter space for these pure plant oils. Two-phase flow imaging inside the exit orifice shows that for the pure plant oils, the flow is highly transient at low GLRs and the bubbly, slug, and annular two-phase flow regimes are all observed. However, at higher GLRs where the spray is steady, only the annular flow regime is observed.

Micro-Raman and photoluminescence studies of self-assembled quantum well microtubes on GaAs substrate

The Semiconductor Quantum Well (QW) microtubes have been fabricated by strain-induced self assembling technique. Three types of multilayer structures have consisted of GaAs/InxGa1-xAs strained layers containing with various thickness of Monolayers of (GaAs/AlGaAs) QW were grown by Varian Gen II Molecular Beam Epitaxy (MBE) on the GaAs (100) substrate. The shape of the rolled up microtubes provide a clear idea about the formation of three dimensional micro- and nanostructures. Micro-Raman and photoluminescence (PL) studies were performed to the QW microtubes and as compared with their grown area on the GaAs substrate. The results of Raman spectra show the frequency shift of phonon modes measured in tube and compared with the grown area due to residual strain. The PL peaks of the microtube were red-shifted due to the strain effect and transition of bandgap from Type-II to Type-I. (C) 2013 Elsevier B.V. All rights reserved.

Biodegradation of acrylamide and purification of acrylamidase from newly isolated bacterium Moraxella osloensis MSU11

The increasing industrial utilization of polyacrylamide to assist water clarification, sludge conditioning, papermaking, and secondary oil recovery leads to environmental pollution. In this work, an acrylamide degrading bacterium was isolated from paper mill effluent at Charan mahadevi, Tamilnadu, India. The minimal medium containing acrylamide (40 mM) served as a sole source of carbon and nitrogen for acrylamide degrading bacteria. The bacterial strain has grown well in 40 mM acrylamide at pH (6-7) at 30 degrees C. Within 24-48 h acrylamide was converted into acrylic acid and other metabolites. Based on biochemical characteristics and 16S rRNA gene sequence, the bacterial strain was identified as Gram negative, diplobacilli Moraxella osloensis MSU11. The acrylamide hydrolyzing bacterial enzyme acrylamidase was purified by HPLC. The enzyme molecular weight was determined to be approximately 38 kDa by SDS-PAGE using reference enzyme Pectinase. These results show that M. osloensis MSU11 has a potential to degrade the acrylamide present in the environment. (C) 2013 Elsevier Ltd. All rights reserved.

FLOTATION OF QUARTZ WITH SOAPS OF BOMBAX MALABARICA OIL AND SHARK LIVER OIL AS COLLECTORS

An attempt has been made to use the indigeneous oils-Bombax Malabarica oil and Shark liver oil in the form of sodium soaps as collectors in the flotation of quartz using barium chloride as activator. The effect of pH, collector concentration and activator concentration on the flotation of quartz is studied in a Leaf and knoll flotation cell. The experiments show that it is possible to obtain 98.0 per cent of quartz as float using 10 mg. of Bombax. Malabarica oil and Shark liver oil soaps at pH values of more than 7.0 and when barium ion concentration is in excess of that required to form barium soaps. Bombax Malabarica oil is found to be superior to Shark liver oil as collector in the flotation of quartz.

Moisture Aided Degradation of Oil Impregnated Paper Insulation in Power Transformers

The presence of moisture in oil impregnated paper insulation (OIP) is detrimental to its long time performance. Until recently, it was thought insulation ageing was only a function of temperature and electrical stress. It has now been realized that moisture in all its forms causes rapid degradation of the electrical and mechanical properties with time. In this study, insulation paper samples were conditioned for desired level of moisture and were impregnated with premium quality transformer oil. The oil impregnated samples with 1 to 3 % moisture content were aged at 90 to 130 C. The indices for determining the extent of ageing considered in this work are degree of polymerization (DP), furan, carbon monoxide and carbon dioxide content. These quantities were monitored throughout the ageing experimental run. End-of-life (EOL) criterion used here is the reduction in the value of DP. Phenomenological models for estimating the service life of insulation are proposed and are validated against actual experimental data.

Nanodiamond-Based Thermal Fluids

Dispersions of nanodiamond (average size similar to 6 nm) within dielectric insulator mineral oil are reported for their enhanced thermal conductivity properties and potential applications in thermal management. Dynamic and kinematic viscosities-very important parameters in thermal management by nanofluids-are investigated. The dependence of the dynamic viscosity is well-described by the theoretical predictions of Einstein's model. The temperature dependence of the dynamic viscosity obeys an Arrhenius-like behavior, where the activation energy and the pre-exponential factor have an exponential dependence on the filler fraction of nanodiamonds. An enhancement in thermal conductivity up to 70% is reported for nanodiamond based thermal fluids. Additional electron microscopy, Raman spectroscopy and X-ray diffraction analysis support the experimental data and their interpretation.

Polyanhydrides of Castor Oil-Sebacic Acid for Controlled Release Applications

A family of high molecular weight castor oil (CO)-based biodegradable polyanhydrides was synthesized by a catalyst-free melt-condensation reaction between prepolymers of CO and sebacic acid (SA). The structure of the polymers was characterized by H-1 NMR and Fourier transform infrared spectroscopy, which indicated the formation of the anhydride bond along the polymer backbone. Thermal analysis and X-ray diffraction confirmed the semicrystalline nature of the polymers. Incorporation of SA enhanced the crystallinity of the polymer. The hydrophobic nature of these polymers was revealed by contact angle goniometry. Water wettability decreased with increase in SA content. Compressive tests demonstrated a sharp increase in strength and decrease in ductility with increasing SA content. In vitro hydrolytic degradation studies indicated surface-eroding behavior. The degradation rate decreased with an increase of SA content in the polymers because of increased crystallinity. The release studies of both hydrophobic and hydrophilic dyes followed zero-order kinetics. In vitro cell studies to assess the cytotoxicity of the polymer confirmed minimal toxicity of the degradation products. Thus, a family of CO-SA polyanhydrides have been synthesized and characterized for controlled release applications where the physical, mechanical, and degradation kinetics can be modulated by varying the weight fraction of the prepolymers.

Spectrum of the three-dimensional fuzzy well

We develop the formalism of quantum mechanics on three-dimensional fuzzy space and solve the Schrodinger equation for the free particle, finite and infinite fuzzy wells. We show that all results reduce to the appropriate commutative limits. A high energy cut-off is found for the free particle spectrum, which also results in the modification of the high energy dispersion relation. An ultra-violet/infra-red duality is manifest in the free particle spectrum. The finite well also has an upper bound on the possible energy eigenvalues. The phase shifts due to scattering around the finite fuzzy potential well are calculated.

EXPERIMENTAL STUDIES ON AIR-ASSISTED ATOMIZATION OF JATROPHA PURE PLANT OIL

The present study focuses on exploring air-assisted atomization strategies for effective atomization of high-viscosity biofuels, such as pure plant oils (PPOs). The first part of the study concerns application of a novel air-assisted impinging jet atomization for continuous spray applications, and the second part concerns transient spray applications. The particle/droplet imaging analysis (PDIA) technique along with direct imaging methods are used for the purpose of spray characterization. In the first part, effective atomization of Jatropha PPO is demonstrated at gas-to-liquid ratios (GLRs) on the order 0.1. The effect of liquid and gas flow rates on the spray characteristics is evaluated, and results indicate a Sauter mean diameter (SMD) of 50 mu m is achieved with GLRs as low as 0.05. In the second part of the study, a commercially available air-assisted transient atomizer is evaluated using Jatropha PPO. The effect of the pressure difference across the air injector and ambient gas pressure on liquid spray characteristics is studied. The results indicate that it is possible to achieve the same level of atomization of Jatropha as diesel fuel by operating the atomizer at a higher pressure difference. Specifically, a SMD of 44 mu m is obtained for the Jatropha oil using injection pressures of <1 MPa. A further interesting observation associated with this injector is the near constancy of a nondimensional spray penetration rate for the Jatropha oil spray.

Bolaamphiphiles as carriers for siRNA delivery: From chemical syntheses to practical applications

In this study we have investigated a new class of cationic lipids - ``bolaamphiphiles'' or ``bolas'' - for their ability to efficiently deliver small interfering RNAs (siRNAs) to cancer cells. The bolas of this study consist of a hydrophobic chain with one or more positively charged head groups at each end. Recently, we reported that micelles of the bolas GLH-19 and GLH-20 (derived from vernonia oil) efficiently deliver siRNAs, while having relatively low toxicities in vitro and in vivo. Our previous studies validated that; bolaamphiphiles can be designed to vary the magnitude of siRNA shielding, its delivery, and its subsequent release. To further understand the structural features of bolas critical for siRNAs delivery, new structurally related bolas (GLH-58 and GLH-60) were designed and synthesized from jojoba oil. Both bolas have similar hydrophobic domains and contain either one, in GLH-58, or two, in GLH-60 positively charged head groups at each end of the hydrophobic core. We have computationally predicted and experimentally validated that GLH-58 formed more stable nano sized micelles than GLH-60 and performed significantly better in comparison to GLH-60 for siRNA delivery. GLH-58/siRNA complexes demonstrated better efficiency in silencing the expression of the GFP gene in human breast cancer cells at concentrations of 5 mu g/mL, well below the toxic dose. Moreover, delivery of multiple different siRNAs targeting the HIV genome demonstrated further inhibition of virus production. Published by Elsevier B.V.

Part II: Design of Well Doping Profile for Improved Breakdown and Mixed-Signal Performance of STI-Type DePMOS Device

Shallow-trench isolation drain extended pMOS (STI-DePMOS) devices show a distinct two-stage breakdown. The impact of p-well and deep-n-well doping profile on breakdown characteristics is investigated based on TCAD simulations. Design guidelines for p-well and deep-n-well doping profile are developed to shift the onset of the first-stage breakdown to a higher drain voltage and to avoid vertical punch-through leading to early breakdown. An optimal ratio between the OFF-state breakdown voltage and the ON-state resistance could be obtained. Furthermore, the impact of p-well/deep-n-well doping profile on the figure of merits of analog and digital performance is studied. This paper aids in the design of STI drain extended MOSFET devices for widest safe operating area and optimal mixed-signal performance in advanced system-on-chip input-output process technologies.

Understanding transitions in a rural Indian building typology in the context of well-being

Rural settlements in Karnataka in India predominantly use locally available resources to build their dwelling units. The houses are constructed either by the villagers themselves or by local masons skilled in traditional architecture. However, traditional houses and lifestyle are slowly giving way to modern concrete dwellings and a new lifestyle. To analyse this trend of transition to modern dwellings in rural settlements, a case study was conducted in three villages near the city of Bengaluru in Karnataka. The present article discusses this transition in the context of sustainable well-being of rural settlements.