Search

We demonstrate heteroepitaxial growth of single-crystalline-like n and p-type doped GaAs thin films on inexpensive, flexible, and light-weight metal foils by metal-organic chemical vapor deposition. Single-crystalline-like Ge thin film on biaxially textured templates made by ion beam assisted deposition on metal foil served as the epitaxy enabling substrate for GaAs growth. The GaAs films exhibited strong (004) preferred orientation, sharp in-plane texture, low grain misorientation, strong photoluminescence, and a defect density of ~107cm-2. Furthermore, the GaAs films exhibited hole and electron mobilities as high as 66 and 300 cm² /V-s, respectively. High mobility single-crystalline-like GaAs thin films on inexpensive metal substrates can pave the path for roll-to-roll manufacturing of flexible III-V solar cells for the mainstream photovoltaics market. [ABSTRACT FROM AUTHOR]

Highlights: [•] Eu0.5Sr0.5Mn1−x Co x O3 samples are found to be in Pbnm orthorhombic structure. [•] Ground state properties of studied samples are sensitive to Co concentration. [•] Except x =0.1, all other samples show field induced insulator-metal transition. [•] The samples show large (>99.9%) magnetoresistance below insulator-metal transition. [•] Low temperature resistivity depends strongly on previous history of applied field. [Copyright &y& Elsevier]

Alkaline earth metal tungstate compounds activated by trivalent europium (Eu3+) are promising candidates for narrow spectral emission red phosphors suitable for high efficacy white light emitting diodes (LEDs). By growing crystals of these compounds from high temperature flux containing Na+ as the charge compensation element, enhancement in the emission intensity of A1 − xWO4: [ABSTRACT FROM AUTHOR]

Newly developed nanomaterials offer unique opportunities in the fields of industry and medical sciences that are complementary to current technology. Nanomaterials can be obtained through physicochemical processes from various inorganic and organic substances. The properties and functions of materials can be tuned through controlling the composition, structure, and morphology of the nanoparticles. Chitosan is the principle derivative of chitin, which is the second-most naturally occurring polysaccharide after cellulose. Chitosan has an amino group in the C-2 position and OH groups in the C-3 and C-5 positions of each repeat unit and can react with functional nanomaterials through various kinds of reaction mechanisms. There have been several reports on the preparation of nanoparticles and functional nanomaterials and their uses. This chapter summarizes the main advancements in the design and preparation of nanomaterials over the last 10 years, with an emphasis on functionalized metal nanoparticles, carbon nanotubes, graphene, fullerene, liposomes, quantum dots, and nanocomposites, and outlines the current developing interest in functionalization of chitosan derivatives in the form of nanomaterials to provide new strategies for a wide range of applications. [ABSTRACT FROM AUTHOR]

• Structural and magnetic properties of skyrmionic system, Cu 2 OSeO 3 are investigated. • Thermal hysteresis between FC and FCH data is observed. • Lattice distortion at the magnetic transition is noticed. • Large MCE is found near the ferrimagnetic transition for a small change in magnetic field. • The observed anomalous change in Cu(1)-Cu(2) distances tune the strength of the magnetic exchange interactions. [Display omitted] We report here the detailed investigation on structural and magnetic behavior of the polycrystalline sample of Cu 2 OSeO 3. The Mott insulator Cu 2 OSeO 3 is a fascinating material showing skyrmionic state and magneto-electric coupling. We observe clear signature of thermal hysteresis between field-cooled and field-cooled heating data in the low-field magnetization versus temperature curve just below the magnetic ordering temperature of T C ~ 60 K. Temperature dependent powder x-ray diffraction data indicate the presence of lattice anomaly below T C. The sample also shows reasonable value of conventional magnetocaloric effect for small value of applied magnetic field, which can be related to the change in the magnetic structure with field. [ABSTRACT FROM AUTHOR]

Pulmonary Lymphangitis carcinomatosis is an unusual metastatic manifestation of Oesophagogastric carcinoma and it occurs due to diffuse spread of the tumour to the pulmonary lymphatic system. We described a case of a 28 year old woman, presenting with gradually progressive dyspnoea and cough where results of Chest X-ray and HRCT thorax were consistent with features of Lymphangitis carcinomatosis. Upper GI endoscopic evaluation showed a tumour originating from oesophagogastric junction and extending to cardia of stomach. Biopsy from tumour revealed adenocarcinoma. As there is no definitive therapy to this condition, patient was managed conservatively only to succumb few days after hospitalisation. [ABSTRACT FROM AUTHOR]

Abstract Objective: This study assessed the utility of pus, soft tissue, and bone specimens in diagnosing diabetic foot infections and the spectrum of the microbial flora and in vitro susceptibility to antibiotics. Subjects and Methods: This prospective study was carried out in 60 consecutive patients with diabetes having clinically infected foot ulcers. Detailed history, physical examination, and investigation were carried out to diagnose the presence of osteomyelitis and the microbial etiology of foot ulcers. Foot ulcers were classified as per Wagner's classification. Soft tissue, pus, and bone samples were obtained and cultured for aerobic and anaerobic bacteria, and antimicrobial susceptibility testing was carried out as per the standard protocol. Results: Causative bacteria were isolated in 55 of 60 patients, and 157 isolates were cultured from 117 specimens with an average of 1.34 isolates per cases; however, the number of isolates per specimen did not differ among the various types of samples (P=0.78). Pus and soft tissue had predominantly polymicrobial flora, whereas bone infections were monomicrobial. The isolates from soft tissue specimens were different from those from bone and pus in 57% and 54% of cases, respectively. The common bacterial isolates from 117 specimens included Escherichia coli (21%) and Proteus species (15.9%). Nearly 70% of Staphylococcus aureus isolates were methicillin sensitive. All S. aureus and Enterococcus isolates were sensitive to vancomycin. Susceptibility of Gram-negative organisms to ciprofloxacin was 50%. Conclusions: Diabetic foot infections are mostly polymicrobial with Gram-negative predominance. Multiple sampling from superficial and deep tissues, including bone, when involved, yields more relevant information diagnostically and therapeutically. [ABSTRACT FROM AUTHOR]

Background: Pituitary metastasis as a presenting manifestation of silent systemic malignancy is rare. We describe four such cases. Materials and Methods: Four patients (0.7%) of malignancy with pituitary metastasis out of 540 patients of sellar mass within a period of 10 years were analyzed for clinical, hormonal and radiological findings. Result: The age range of these patients was 39-60 years with lag time ranging from 2to 5 months. Pituitary pathology was presenting manifestation in all 4 patients including diabetes insipidus, ophthalmoplegia and variable anterior pituitary hormone deficiency. 2 patients had bronchogenic carcinoma and one each had squamous cell and adenocarcinoma with unknown primary. Diagnosis of pituitary metastasis was confirmed in three on pituitary mass histopathology and in one it was based on rapidly appearing mass in a short time. Conclusion: Rapidly appearing mass in the sellar region, short lag time, sudden onset of ophthalmoplegia, -symptoms and signs disproportionate to the size of mass, presence of diabetes insipidus and destroyed but normal sized sella should invoke the suspicion of pituitary metastasis. [ABSTRACT FROM AUTHOR]

A novel chitosan derivative with ofloxacin (OFX) has been successfully prepared. The IR and 1H-NMR results revealed that the chitosan/ofloxacin (CH-OFX) complex exhibited an electrostatic interaction. The crystalline and surface morphology were analyzed by X-ray diffraction (XRD) and scanning electron microscopy (SEM). The antimicrobial activity of the complexes against various micro-organisms viz. Escherichia coli, Bacillus subtilis, Pseudomonas aeruginosa and Staphylococcus aureus was tested. It was established that their antibacterial activity is up to four times greater than that of free quinolone drug and chitosan, probably due to the conjunction of favorable pharmacokinetics, excellent bacterial susceptibility and good stability towards metabolic degradation. [ABSTRACT FROM AUTHOR]

Abstract: Hydrogenated nanocrystalline silicon (nc-Si:H) films, deposited by reactive radio-frequency sputtering with 33% hydrogen dilution in argon at 200°C, were treated with low-power hydrogen plasma at room temperature at various power densities (0.1–0.5W/cm2) and durations (10s–10min). Plasma treatment reduced the surface root mean square roughness and increased the average grain size. This was attributed to the mass transport of Si atoms on the surface by surface and grain boundary diffusion. Plasma treatment under low power density (0.1W/cm2) for short duration (10s) caused a significant enhancement of crystalline volume fraction and electrical conductivity, compared to as-deposited film. While higher power (0.5W/cm2) hydrogen plasma treatment for longer durations (up to 10min) caused moderate improvement in crystalline fraction and electrical properties; however, the magnitude of improvement is not significant compared to low-power (0.1W/cm2)/short-duration (10s) plasma exposure. The results indicate that low-power hydrogen plasma treatment at room temperature can be an effective tool to improve the structural and electrical properties of nc-Si:H. [ABSTRACT FROM AUTHOR]

The efficient procedure for preparation of chitosan acid salts in isopropyl alcohol under mild condition has been demonstrated. The salts were prepared by dissolving chitosan into ascorbic acid, p-amino benzoic acid and p-nitro benzoic acid, respectively, and then washed with an isopropyl/water mix-solvent. The prepared crystal salt and molecular conformation of modified chitosan derivatives are characterized by using ultraviolet, Fourier transform infrared (FTIR), 1H nuclear magnetic resonance (NMR), X-ray diffraction and Circular dichroism (CD) techniques. The formation of salts was confirmed by FTIR (∼1,523–1,557 cm−1) and NMR (∼7–8 ppm) with respect to the bonding between NH2 group on chitosan and COOH group on acid. The CD spectra of chitosan salts showed negative at (253, 285 and 295 nm band) in chitosan ascorbic acid, p-amino benzoic acid and p-nitro benzoic acid salt respectively in DMSO, indicating that the polymer adopted a helical secondary structure. The polymers are highly soluble in a wide pH range, which opens new perspectives for the biomedical application of chitosan based-materials. [ABSTRACT FROM AUTHOR]

Here we prove a probabilistic contraction mapping principle in Menger spaces. This is in line with research in fixed point theory using control functions which was initiated by Khan et al. [Bull. Austral. Math. Soc., 30(1984), 1-9] in metric spaces and extended by Choudhury et al. [Acta Mathematica Sinica, 24(8) (2008), 1379-1386] in probabilistic metric spaces. An example has also been constructed. [ABSTRACT FROM AUTHOR]

Abstract: This paper presents the results of an investigation on the efficacy of hybrid compression process for refrigerant HFC 134a in cooling applications. The conventional mechanical compression is supplemented by thermal compression using a string of adsorption compressors. Activated carbon is the adsorbent for the thermal compression segment. The alternatives of bottoming either mechanical or thermal compression stages are investigated. It is shown that almost 40% energy saving is realizable by carrying out a part of the compression in a thermal compressor compared to the case when the entire compression is carried out in a single-stage mechanical compressor. The hybrid compression is feasible even when low grade heat is available. Some performance indictors are defined and evaluated for various configurations. [Copyright &y& Elsevier]

Experimental and numerical studies on macrosegregation during directional solidification of an aqueous ammonium chloride solution in a rectangular cavity are presented. Depending on the initial concentration and boundary temperature conditions, three distinct situations in the liquid during the solidification process are studied: mass diffusion only, solutal convection and double diffusive convection. The time dependent concentration of the solution inside the cavity is measured online for the above three situations using a laser based technique. This technique measures refractive index of the solution, which indirectly gives the concentration variation at a point in the solution during solidification. The interface growth is photographed using a shadowgraph technique, and the flow is visualised using a sheet of laser light scattered by neutrally buoyant, hollow glass spheres seeded in the fluid. Corresponding numerical studies are performed using a macroscopic model based on a fixed grid, enthalpy based, control volume approach. A good agreement between the experimental and computational results is observed. [ABSTRACT FROM AUTHOR]

Abstract: This paper discusses moderate pressure CO2 sorption behavior of Illinois coals. The results fit the Langmuir and Dubinin–Astakhov (D–A) sorption models satisfactorily although the fit is better for D–A equation. Since factors like swelling of coal with CO2 sorption and CO2 dissolution in coal matrix contribute to uncertainties in estimating the void volume in and around the sample, an attempt was made to account for these by modifying the conventional adsorption equation. Re-fitting the experimental data using the modified equation results in improved fit for both models. The adsorption capacities of coals tested, as predicted by the equations, also reduce by 7% to 32%. The effect of volumetric uncertainty is more in lower rank coals than the higher rank ones. Furthermore, it explains the excess sorption behavior observed by others when extrapolated beyond the experimental pressure range. [Copyright &y& Elsevier]

Abstract: Size dependence of the blocking temperature (determined by SQUID magnetometry) and electron magnetic resonance (EMR) spectra are reported for NiO nanoparticles (NPs) with diameter –20 nm. Comparison of the vs. variations in the oleic acid (OA) coated and uncoated NiO NPs is made. The higher blocking temperatures observed for the uncoated NPs are suggested to result from the effects of the interparticles interactions (IPI). For the coated NPs with negligible IPI, the expected linear variation of with volume of the NPs is valid if effective anisotropy constant increases with decreasing . The decreasing intensity of the EMR signal with increasing is suggested to result from the surface Ni2+ spins whose density decreases with increasing D. [Copyright &y& Elsevier]

Abstract: Multiple drug resistance (MDR) represents a major obstacle to successful application of chemotherapy and a basic problem in cancer biology. MDR occurs at the cellular level and is multi-factorial in nature. The multidrug resistance gene, MDR1, and its gene product P-glycoprotein (P-gp) are now well known as an important determinant of MDR. Much effort has been devoted to develop P-gp inhibitors to modulate resistance. However, most of these resistance-modifying agents (RMA) are too toxic at the required doses. Therefore, the development of novel RMAs to overcome MDR represents a major challenge to modern cancer chemotherapy. In the present investigation, we describe the effect of oxalyl bis (N-phenyl) hydroxamic acid (OBPHA) and copper N-(2-hydroxy acetophenone) glycinate (CuNG) on multidrug-resistant P-gp-expressing CEM/ADR5000 T-cell acute lymphoblastic leukemia cells. CuNG, a known depleting agent for glutathione (GSH) and inhibitor of glutathione S-transferase (GST) and multidrug resistance-related protein 1 (MRP1), also inhibited P-gp-mediated doxorubicin accumulation and retention. The resistance-modifying effects of OBPHA were stronger than that of CuNG. Both novel RMAs overcame drug resistance more efficiently than verapamil, a well-known P-gp inhibitor. OBPHA and CuNG exposure resulted in an increased doxorubicin accumulation after 1–3h incubation by down-regulation of P-gp expression after 24h incubation. This is a clue that different mechanisms may contribute to modulation of P-gp-mediated drug resistance by these compounds. [Copyright &y& Elsevier]

Analytical solutions for the temperature distribution, heat transfer coefficient, and Nusselt number of steady electroosmotic flows with an arbitrary pressure gradient are obtained for two-dimensional straight microchannels. The thermal analysis considers interaction among advective, diffusive, and Joule heating terms in order to obtain the thermally developing behavior of mixed electroosmotic and pressure-driven flows with isothermal boundary conditions. Heat transfer characteristics are obtained for low Reynolds number microflows where the viscous and electric field terms are very dominant. The electroosmotic component of the flow velocity is modelled with Helmholtz-Smoluchowski slip velocity, and the mixed flow velocity is presented as linear superposition of pure electroosmotic velocity and plane Poiseuille velocity. In mixed flow cases, the governing equation for energy is not separable in general. Therefore, we introduced a method that considers the extended Graetz problem. Analytical results show that the heat transfer coefficient of mixed electroosmotic and pressure-driven flow is smaller than that of pure electroosmotic flow. For the parameter range studied here (Re<0.7), the fully developed Nusselt number is independent of the thermal Peclet number for both pure electroosmotic and mixed electroosmotic-pressure driven microflows. In mixed electroosmotic and pressure-driven flows, the thermal entrance length increases with the imposed pressure gradient. [Copyright &y& Elsevier]

Abstract: One of the important pathways of resistance to anthracyclines is governed by elevated levels of glutathione (GSH) in cancer cells. Resistant cells having elevated levels of GSH show higher expression of multidrug-resistant protein (MRP); the activity of glutathione S-transferases (GSTs) group of enzymes have also been found to be higher in some drug-resistant cells. The general mechanism in this type of resistance seems to be the formation of conjugates enzymatically by GSTs, and subsequent efflux by active transport through MRP (MRP1–MRP9). MRPs act as drug efflux pump and can also co-transport drugs like doxorubicin (Dox) with GSH. Depletion of GSH in resistant neoplastic cells may possibly sensitize such cells, and thus overcome multidrug resistance (MDR). A number of resistance modifying agents (RMA) like dl-buthionine (S, R) sulfoxamine (BSO) and ethacrynic acid (EA) moderately modulate resistance by acting as a GSH-depleting agent. As most of the GSH-depleting agents have dose-related toxicity, development of non-toxic GSH-depleting agent has immense importance in overcoming MDR. The present study describes the resistance reversal potentiality of novel copper complex, viz., copper N-(2-hydroxy acetophenone) glycinate (CuNG) developed by us in Dox-resistant Ehrlich ascites carcinoma (EAC/Dox) cells. CuNG depletes GSH in resistant (EAC/Dox) cells possibly by forming conjugate with it. Depletion of GSH results in higher Dox accumulation that may lead to enhanced rate of apoptosis in EAC/Dox cells. In vivo studies with male Swiss albino mice bearing ascitic growth of EAC/Dox showed tremendous increase in life span (treated/control, T/C=453%) for the treated group with apparent regression of tumor. Resistance to Dox in EAC/Dox cells is associated with over expression of GST-P1, GST-M1 (enzymes involved in phase II detoxification) and MRP1 (a transmembrane ATPase efflux pump for monoglutathionyl conjugates of xenobiotics). CuNG causes down regulation of all these three proteins in EAC/Dox cells. The effect of CuNG as RMA is better than BSO in many aspects. [Copyright &y& Elsevier]

Abstract: A simple and an eco-friendly process for the hydration of 3-cyanopyridine to nicotinamide in the presence of manganese dioxide catalyst has been described. The reaction is conducted at moderate temperature with the reaction times of 5–8h using an aqueous solution of 3-cyanopyridine. The effect of various reaction parameters on the yield of nicotinamide was studied. In most instances, nearly quantitative yields of amides are obtained without any by-products. The IR and ESCA findings of the catalysts are correlated with the catalytic activity. [Copyright &y& Elsevier]

Abstract: This study covers the performance of three cobalt-based catalytic systems (high surface area 15% Co/SiO2, low surface area 15% Co/SiO2, and 15% Co/Al2O3) of different characteristics in Fischer–Tropsch synthesis (FTS) in both conventional gas-phase and supercritical hexane (SCH) phase. The reaction was conducted in a high-pressure FTS reactor setup at reaction temperature of 240°C, syngas (H2/CO ratio of 2) flow rate of 50sccm/gcat, and total pressures from 20 to 65bar. The surface characteristics of these catalysts were measured by N2 physisorption using a TriStar 3000 gas adsorption analyzer. Room temperature X-ray diffraction (XRD), temperature and magnetic field (H) variation of the magnetization (M), and low-temperature (5K) electron magnetic resonance were used for determining the electronic states (Co0, CoO, Co3O4, Co2+) of cobalt for the calcined, reduced (before the reaction), and used samples (after the reaction). Correlations of the catalyst activity and selectivity with the catalysts surface characteristics reveal that pore radius of the catalyst has an influence on both syngas and CO conversions in gas-phase FTS. However, no such correlation was observed in the case of SCH-FTS, indicating an alleviation of that mass transfer limitations typically controlled by interparticle characteristics of the catalyst. This is attributed to the higher solubility of heavy products in the SCH medium that inhibits the condensation of those products inside the catalyst pores and enhances their in situ extraction. The XRD and magnetic characterizations of the used catalysts reveal that in situ reducibility of the Co3O4 to hcp-Co0 or fcc-Co0 is taking place during the FTS reaction. However, minimal in situ reduction was observed in the case of gas-phase FTS, whereby significant changes in the reduced cobalt electronic state and support (alumina, and silica) phase were detected under SCH-FTS conditions. As a result, both the activity and selectivity of the cobalt catalyst was found to be very stable and recoverable during SCH-FTS for relatively long time-on-stream (15 days). [Copyright &y& Elsevier]

The evolution of microstructure during continuous laser welding of dissimilar metals has been studied for a binary Cu–Ni couple. The effects of laser beam scan speed and laser power on the shape and size of the melt pool, the weldment–substrate interface, the composition profiles, and microstructures of the weldments have been investigated. It is shown that the melt pools exhibit a characteristic asymmetry in shape. The observed microstructure is characterised by the existence of compositional and microstructural variations leading to a banded appearance suggesting localised mixing. Distinct differences exist in the evolution of the microstructure in the copper and nickel sides of the weld pool. An attempt is made to explain some of the experimental observations using thermodynamic and thermal transport arguments. [ABSTRACT FROM AUTHOR]

Pituitary apoplexy presenting as frontal lobe syndrome is rare. Interestingly, in our patient the frontal lobe infarct was as a result of intense anterior cerebral artery spasm consequent to nonaneurysmal subarachnoid haemorrhage. The mechanisms of cerebral infarct associated with pituitary apoplexy are discussed. [ABSTRACT FROM AUTHOR]

This paper presents a computational model for heat transfer in direct fired pusher type reheat furnaces for heating steel billets prior to plastic working. Radiation, which is the dominant mode of heat transfer in the furnace chamber, is modelled in a detailed manner. The model incorporates several features of radiation heat transfer that are typical of reheat furnaces, such as non-grey participating gas in the chamber and specular/diffuse reflection off the furnace surfaces. Radiation heat transfer in the furnace chamber and conduction within the billets are modelled using the finite volume method (FVM). Convection heat flux on the billets is calculated using correlations from the literature. Overall, the model is capable of predicting the radiative heat flux distribution within the furnace, as well as the resulting temperature distribution within the billets as they pass through various zones in the furnace. Several key process parameters have been identified, and their effects on the heating process of the billets are studied. [ABSTRACT FROM AUTHOR]

Abstract: This paper presents a single-period inventory problem in an imprecise and uncertain mixed environment. The aim of this paper is to introduce demand as a fuzzy random variable. To determine the optimal order quantity a new methodology is developed for this model in presence of fuzzy random variable demand where the optimum is achieved using a graded mean integration representation. To illustrate the model the classical newsboy problem is considered. [Copyright &y& Elsevier]

Abstract: A homogeneous, isotropic porous matrix of activated carbon inside a portable steel cylinder is considered as the adsorption bed for natural gas (NG) which is idealized as pure methane for the purpose of simulation. The heat and fluid flow inside the porous adsorption bed are modeled using a volume averaging technique and Darcy–Brinkman formulation. The effective thermal conductivity of the activated carbon–methane system is calculated as a function of uptake according to the Luikov model. Heat generation due to the exothermic process of adsorption is considered. The governing equations are solved using an implicit finite volume method for the given boundary conditions. Three different models of adsorption are considered, namely (i) a no-flow model, (ii) flow model with uniform adsorption and (iii) a flow model with local adsorption. For each of these models, transient temperature profiles in the adsorption bed during the charging process are obtained, and the corresponding mass adsorption potentials are calculated. Parametric studies are performed to investigate the effects of gas inlet temperature and rate of charging on the maximum bed temperature and the time required to fill the cylinder. [Copyright &y& Elsevier]

Catalytic conversion of methanol to hydrocarbons with the special emphasis on lower olefins (ethylene and propylene) was carried out using 12-heteropoly acids of W and Mo and P or Si and salts of 12-heteropoly acids. Amongst the metal salts of tungstophosphoric acid, cesium salt exhibited better activity and selectivity for the formation of ethylene and propylene. The maximum selectivity for C2–C4 olefins was 60.7%. Physico-chemical characterization of the catalysts has been made by FTIR spectroscopy, XRD, DTA, acidity by n-butyl amine titration and surface area. Acidity and surface area of the catalysts influence the activity and selectivity for the olefins.Oligomerization of ethylene to higher olefins was carried out in liquid phase using TiCl4–Et3Al2Cl3, TiCl4–Et2AlCl, TiCl4–Et3Al and Ti(OBu)4–Et3Al2Cl3 catalyst systems. Among the catalysts tried, TiCl4 and Ti(OBu)4 based catalysts showed better activity and selectivity to alpha olefins in the range C4–C14. For vapour phase, HZSM-5, nickel salt supported on SAPO-5 molecular sieve, ZSM-5 and γ-alumina, heteropoly acid supported on ZSM-5 and potassium salt of tungstophosphoric acid were tested. The maximum selectivity of C4–C6 olefins was 10.0wt.% with HZSM-5 catalyst with a Si/Al ratio of 100. The selectivity for higher olefins was less than that obtained by liquid phase oligomerization of ethylene. [Copyright &y& Elsevier]

The influence of high content of MoO3 (32mol%) in V2O5–MoO3–P2O5 catalyst system supported on alumina, silica, HZSM-5 and modified clay was investigated for ammoxidation of 3-picoline. Unsupported VMPO catalyst and supported catalysts were prepared by incipient wet impregnation method keeping the mole ratio of V2O5–MoO3–P2O5 (1.00:3.27:0.14) constant. FT-IR spectra and X-ray diffractograms showed interaction among the active oxides and the support. The major phases identified were Mo4V6O25, Mo6V9O40 and MoV2O8. TG–DTA also showed the exothermic peaks indicating the formation of new compounds above 400°C. The physico-chemical properties of the catalysts were correlated with their activity and selectivity for ammoxidation of 3-picoline. The unsupported catalyst showed 96.0% selectivity whereas VMPO/HZSM-5 showed the highest selectivity (91.3%) amongst the supported catalysts. [Copyright &y& Elsevier]

Results of the characterization of six Co-based Fischer–Tropsch (FT) catalysts, with 15% Co loading and supported on SiO2 and Al2O3, are presented. Room temperature X-ray diffraction (XRD), temperature and magnetic field (H) variation of the magnetization (M), and low-temperature (5 K) electron magnetic resonance (EMR) are used for determining the electronic states (Co0, CoO, Co3O4, Co2+) of cobalt. Performance of these catalysts for FT synthesis is tested at reaction temperature of 240 °C and pressure of 20 bars. Under these conditions, 15% Co/SiO2 catalysts yield higher CO and syngas conversions with higher methane selectivity than 15% Co/Al2O3 catalysts. Conversely the Al2O3 supported catalysts gave much higher selectivity towards olefins than Co/SiO2. These results yield the correlation that the presence of Co3O4 yield higher methane selectivity whereas the presence of Co2+ species yields lower methane selectivity but higher olefin selectivity. The activities and selectivities are found to be stable for 55 h on-stream. [ABSTRACT FROM AUTHOR]

A three-dimensional model has been developed to study turbulent fluid flow and heat transfer in a gas metal arc weld pool. The phase change process during melting and solidification is modelled using the enthalpy–porosity technique. Mass and energy transports by droplet transfer are considered through a thermal analysis of the electrode. The droplet heat addition into the molten pool is considered to be in the form of a volumetric heat source distributed in an imaginary cylindrical cavity within the weld pool ('cavity' model). A two-equation k-ε model capable of addressing turbulent weld pool convection, taking into account the morphology of the phase change, is presented. The weld pool dynamics and geometry (shape and size) in a moving gas metal arc welding (GMAW) process are studied and the effects of enhanced diffusivities on the turbulent weld pool are discussed. The predicted weld pool geometry using laminar and turbulent models is also compared with corresponding experimental post-weld sections. [ABSTRACT FROM AUTHOR]

A method to determine the electronic state and concentration of Ni in Ni-loaded silicoaluminophosphate (NiSAPO-n) where n denotes the structure type (n=47, 18, 34, 44, 56and 17) is presented. The method involves measurements and analysis of the magnetization M versus magnetic field H (up to 55kOe at 2K) and M versus temperature (T=2–300K) data. The analysis yields spin S=1/2 corresponding to Ni(I) state for lightly doped samples, whereas for higher doping, both Ni(I) and Ni(0) are indicated. The concentration of Ni determined from these studies varies between the minimum of 0.2wt% for the n=47 sample to maximum of 1.75% for the n=17 sample. [ABSTRACT FROM AUTHOR]

For NiO nanorods of 5 nm diameter prepared by sol–gel technique, variations of the magnetization M with temperature T (5–370 K) and magnetic field H up to 55 kOe are reported. Also, temperature variations of the EMR (electron magnetic resonance) parameters (intensity I0, linewidth ΔH and resonance field Hr) of an observed line due to uncompensated spins are followed for T≤300 K. The M vs. H and T variations yield a blocking TB≃250 K, above which the data fits modified Langevin function with magnetic moment μp≃1240 μB/particle. For the EMR line, I0 decreases rapidly for T and the line broadens and shifts to lower H with lowering T, following the lineshift δHr=(ΔH)n with n≃2.8. This is close to the value of n=3 expected for randomly oriented particles. [Copyright &y& Elsevier]

The electron transport process in DNA-doped polypyrrole (PPY) nanocomposite film deposited on tin oxide coated glass by a simple electrodeposition technique is demonstrated here. Optical absorbance spectra clearly exhibited features corresponding to doped PPY nanocomposite film. The I–V characteristics of the films were non-ohmic and showed a significant change when illuminated with light. Photoinduced I–V profiles suggested carrier hopping to be the dominant transport mechanism in the nanocomposite PPY film. The temperature-dependent dc electrical conductivity data showed a crossover from variable-range hopping to thermally activated hopping of electrons with the increase in temperature. The ac electrical transport properties displayed a frequency-independent region below a characteristic frequency of [inline image] kHz, above which the conductivity showed a strong frequency-dependent behaviour. [ABSTRACT FROM AUTHOR]

Detailed structural and magnetic investigations have been performed on two equally Fe-doped MnCoGe alloys of nominal compositions Mn 0.875 Fe 0.125 CoGe and MnCo 0.875 Fe 0.125 Ge. The presence of martensitic phase transition (MPT) in both alloys is clear from the temperature variation of structural and magnetic properties. The nature of MPT is found to be complete in the Mn site Fe-doped alloy. On the other hand, a partial nature of the MPT is observed for the Co site Fe-doped alloy. The application of external hydrostatic pressure hardly affects the magnetic and structural transition temperatures. Both alloys show a significant amount of the magnetocaloric effect in ambient as well as in high pressure situation around their magnetic and structural transition regions. [ABSTRACT FROM AUTHOR]

Advancement of gas sensor technology over the past few decades has led to significant progress in pollution control and thereby, to environmental protection. An excellent example is the control of automobile exhaust emissions, made possible by the use of oxygen gas sensors. Since early 1970's there have been sustained studies on oxygen sensors and has led to development of sensors for various applications with varying performance characteristics. Solid electrolyte based potentiometric, amperometric and metal oxide based semiconducting resistive type sensors are used for high temperature applications. For solution-based pollution monitoring, dissolved oxygen sensors based on Clark electrodes have played a major role. More recently, for biological and medical applications, optical oxygen sensors are beginning to have an impact. In this review, we focus on both high temperature as well as dissolved oxygen sensors and compare the different methods of oxygen sensing, discuss underlying principles, and outline the designs and specific applications. [ABSTRACT FROM AUTHOR]

The electrical conductivity both dc and ac of polypyrrole doped with β-naphthalenesulfonicacid (NSA) and polypyrrole–polymethyl methacrylate blends have been investigated in the temperature range of 300–80 K and in the frequency range of 100–10 MHz. Samples are prepared by in situ polymerisation technique using the common solvent meta cresol. The frequency dependence of conductivity satisfies the power law, σ(ω)∝ωs, with s=0.73–0.95. In PPY–NSA, s is independent of temperature and explained by electron tunneling model whereas in PPY(NSA)–PMMA blend s decreases with temperature and the ac mechanism is predicted by the overlapping polaron tunneling. The ac conductivity σ(ω) as a function of temperature follows the scaling law, σ(ω)/σ0=1+(ω/ω0)n with n≃0.85. [Copyright &y& Elsevier]

A three-dimensional transient mathematical model (following a fixed-grid enthalpy-based continuum formulation) is used to study the interaction of double-diffusive natural convection and non-equilibrium solidification of a binary mixture in a cubic enclosure cooled from a side. Investigations are carried out for two separate test systems, one corresponding to a typical model “metal–alloy analogue” system and other corresponding to a real metal–alloy system. Due to stronger effects of solutal buoyancy in actual metal–alloy systems than in corresponding analogues, the convective transport mechanisms for the two cases are quite different. However, in both cases, similar elements of three-dimensionality are observed in the curvature and spacing of the projected streamlines. As a result of three-dimensional convective flow patterns, a significant solute macrosegregation is observed across the transverse sections of the cavity, which cannot be captured by two-dimensional simulations. [Copyright &y& Elsevier]

The use of microfabricated cantilevers as bioaffinity sensors was investigated. Since many bioaffinity interactions involve proteins as receptors, we conducted studies of the magnitude, kinetics, and reversibility of surface stresses caused when common proteins interact with microcantilevers (MCs) with nanostructured (roughened) gold surfaces on one side. Exposure of nanostructured, unfunctionalized MCs to the proteins immunoglobulin G and bovine serum albumin (BSA) resulted in reversible large tensile stresses, whereas MCs with smooth gold surfaces on one side produced reversible responses that were considerably smaller and compressive. The response magnitude for nanostructured MCs exposed to BSA is shown to be concentration dependent, and linear calibration over the range of 1-200 mg/L is demonstrated. Stable, reusable protein bioaffinity phases based on unique enantioselective antibodies are created by covalently linking monoclonal antibodies to nanostructured MC surfaces. The direct (label-free) stereoselective detection of trace amounts of an important class of chiral analytes, the α-amino acids, was achieved based on immunomechanical responses involving nanoscale bending of the cantilever. The temporal response of the cantilever (Δ deflection/Δ time) is linearly proportional to the analyte concentration and allows the quantitative determination of enantiomeric purity up to an enantiomeric excess of 99.8%. To our knowledge, this is the first demonstration of chiral discrimination using highly scalable microelectromechanical systems. [ABSTRACT FROM AUTHOR]

The dielectric relaxation spectroscopy of HCl-doped PANI–PVA composites have been investigated in the temperature range 110–300 K and in the frequency range 200 Hz–10 MHz near the percolation threshold. A large value of the dielectric constant has been observed at high temperature and low frequency. The complex dielectric constant ∊&ast;(ω) has been described by the electric modulus M&ast;(ω)=(1/∊&ast;(ω))=M′(ω)+iM″(ω). The data of M&ast;(ω) has been analysed by the stretched exponential decay of the electric field, φ(t)=exp−(t/τ0)β, where 0<β≤1. The temperature dependence of M′(ω) and M″(ω) obey a single master curve with β=0.79. [Copyright &y& Elsevier]

A numerical study of three-dimensional heat transfer and fluid flow in a moving gas metal arc welding (GMAW) process is performed by considering various driving forces of fluid flow such as buoyancy, Lorentz force, and surface tension. The computation of the current density distribution and the resulting Lorentz force field is performed by solving the Maxwell equations numerically in the domain of the workpiece. The phase change process during melting and solidification is modeled using the enthalpy-porosity technique. Mass and energy transports by droplet transfer are also considered through a thermal analysis of the electrode. The droplet heat addition to the molten pool is considered to be a volumetric heat source distributed in an imaginary cylindrical cavity within the weld pool ("cavity" model). This nature of the heat source distributed due to the falling droplets takes into account the momentum and thermal energy of the droplets. The numerical model is able to capture the well-known "finger" penetration commonly observed in the GMAW process. Numerical prediction regarding the weld pool shape and size is compared with the corresponding experimental results, showing good qualitative agreement between the two. The weld pool geometry is also found to be dependant on some key parameters of welding, such as the torch speed and power input to the workpiece. [ABSTRACT FROM AUTHOR]

Unlabelled: A double-blind, randomized, controlled trial was conducted to compare the clinical efficacy of hypo-osmolar oral rehydration salts (ORS) solution (224 mmol/L) and standard ORS solution (311 mmol/L) in children with persistent diarrhoea who were prone to develop dehydration. Initially, 95 children aged between 3 and 24 mo were included in the study for overnight observation. Of these, 70 children who passed stool more than 2 g/kg/h were finally enrolled in the study and were randomly assigned either standard ORS or hypo-osmolar ORS. After decoding the identity of ORS, it was observed that 37 children were in the standard ORS group and 33 in the hypo-osmolar ORS group. Clinical parameters and microbiological findings of stool samples were comparable in the two groups at the time of enrolment. Total stool output (2.5+/-1.1 vs 3.2+/-1.6 kg; p = 0.04), duration of diarrhoea (114.8+/-38.3 vs 145.4+/-40.0 h; p = 0.002), total intake of ORS (5.4+/-1.6 vs 7.8+/-1.8 l; p = 0.002) and total fluid intake (7.9+/-2.6 vs 10.0+/-4.1 l, p = 0.01) were significantly less in the hypo-osmolar ORS group compared to the standard ORS group. However, the percentage of weight gain on recovery in the hypo-osmolar group was less compared to that of the standard ORS group, though the difference was statistically insignificant. Thirty-five (95%) children in the standard ORS and 33 (100%) children in the hypo-osmolar group recovered within 10 d of initiation of therapy and modified dietary management.Conclusion: Our findings suggest that hypo-osmolar ORS has beneficial effects on the clinical course of dehydrating persistent diarrhoea. [ABSTRACT FROM AUTHOR]

• Stack-based thermal resistance network model developed for micro channel heat exchangers. • Correlations developed with straight, sinusoidal and zigzag channels for sCO 2 recuperator. • Hybrid model demonstrates that 20 rows are sufficient to attain the correct stack performance. • Several combinations of stack dimensions generated for different channel configurations. • Sinusoidal channel offered least pressure drop and stack volume compared to straight and zigzag channels. In this work, a full-scale Thermal Resistance Network (TRN) coupled with a unit-cell-based CFD model identified as the hybrid model is developed and implemented in designing a Mini Channel Heat Exchanger (MCHE) as a recuperator used in sCO 2 Brayton power block. The TRN framework converts the MCHE domains into a thermal circuit using resistances and advection currents that can be used to model the entire stack with varying thermo-physical properties of working fluids. The results from the TRN model with CFD-based heat transfer and pressure drop correlations developed for different channel lengths, are compared with the original CFD data to ascertain the lowest possible channel length for precise correlation development. An appropriate channel length is further used for deriving correlations for sinusoidal and zigzag flow paths. The hybrid model helps determine the upper limit of the side width (fin width) of the channels based on equivalent thermal resistance between fluid and walls as the lower limit is constrained by stress criteria. The present model estimates that at least 20 rows/plates need to be modelled for the correct performance estimation of a full-scale MCHE. The minimum rate of heat loss-based stack optimization approach is implemented in estimating the optimum number of rows and stack dimensions. The channel and stack dimensions are obtained and compared for straight, sinusoidal, and zigzag flow paths for Reynolds numbers ranging from 5 × 103 to 20 × 103, ensuring a temperature pinch of 5 °C at the cold inlet. For cold inlet Reynolds number and channel diameter of 1.5 × 104 and 1.5 mm, the stack volumes for straight, zigzag, and sinusoidal channels are 1.8 m3, 1.21 m3, and 1.15 m3, respectively with sinusoidal and zigzag paths resulting in almost similar pressure drop as ∼110 Pa, 27% lower compared to the straight channel. The article presents a guideline for hybrid model implementation in designing mini/micro channel heat exchangers. [ABSTRACT FROM AUTHOR]

A hospital-based case-control study was carried out to clarify the characteristics of mucoid presentation of acute enterocolitis in children. One hundred sixty-eight cases of acute mucoid enterocolitis (study population) were compared with 200 cases of watery diarrhoea and 118 cases of blood dysentery (control groups) on the basis of clinical characteristics and findings on stool examination. Study and control groups were comparable with respect to age, body weight and nutritional status. There was no significant difference in clinical characteristics (duration of diarrhoea, stool frequency, presence of vomiting, fever and dehydration) between patients suffering from mucoid enterocolitis and blood dysentery. However, watery diarrhoea patients had significantly high frequencies of vomiting (p = 0.00001) and dehydration (p = 0.00001). High numbers of microscopic red blood cells (mean ± SD: 40.8 ± 16.8) and white blood cells (40.6 ± 18.0) were present in faecal samples of the patients with mucoid enterocolitis, which is indicative of infection caused by enteroinvasive enteropathogens. Shigella was a commonly identified enteropathogen in patients with mucoid enterocolitis (40.5%) and in patients with dysentery (46.6%), with no statistically significant difference (p = 0.30). Isolation of Salmonella was statistically similar in study and control groups. However, Entamoeba histolytica was detected in significantly high frequency in patients with mucoid enterocolitis as compared to the patients with dysentery (p = 0.0004) and watery diarrhoea (p = 0.00004). Our results indicate that mucoid enterocolitis patients are infected with enteroinvasive enteropathogens, and that stool examination is useful in establishing the aetiological diagnosis. [ABSTRACT FROM AUTHOR]

Presents information on a study which described a blind deconvolution method which allows the deconvolution of broad-band signals. Application of blind deconvolution on data obtained from liquid chromatography and deep level transient spectroscopy; Examples; Conclusions.