Effect of chromium aging on the structural and thermal properties of chromium polyacrylate

The effects of aging time of Cr(III) solutions on the structural, thermal, magnetic, and morphological properties of chromium polyacrylate complexes were studied. Chromium retention was found to increase with longer aging periods. IR spectra revealed the formation of polychelate structures with noticeable changes on aging. The interaction of multivalent, polynuclear Cr(III) species with the polymer backbone resulted in a decrease in thermal stability for the complexes prepared from olated chromium solutions. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 98: 490–493, 2005     

Adenosine triphosphate (ATP) and other nucleotides stimulate the hydrolysis of phosphatidylethanolamine in intact fibroblasts

Addition of adenosine triphosphate (ATP) to [¹⁴C]ethanolamine-prelabeled NIH 3T3 fibroblasts resulted in rapid formation of [¹⁴C]ethanolamine from the prelabeled cellular phosphatidylethanolamine (PtdEtn) pool. After 2-min exposure, 10 μM ATP had near maximal effects on PtdEtn hydrolysis. Several other nucleotides, including UTP, ITP, and the stable ATP analog adenosine 5′-O-(3-thiotriphosphate) (ATPγS), also had stimulatory effects on PtdEtn hydrolysis with a potency comparable to that observed with ATP. The same nucleotides which acted on PtdEtn hydrolysis also had similar stimulatory effects on the hydrolysis of phosphatidylcholine (PtdCho) in [¹⁴C]choline-labeled cells. In isolated membranes, Mg²⁺ greatly enhanced the stimulatory effects of ATP and ATPγS, but not of other nucleotides, on the hydrolysis of PtdEtn and PtdCho. Results indicate that in isolated membranes, both ATP and ATPγS stimulate phospholipid hydrolysis by two different mechanisms, but in intact cells only one of these mechanisms appears to be responsive to externally added nucleotides.     

An Indo-Soviet experiment on anmhd generator test section at the Soviet U-02 facility

This paper summarizes the major results of the joint Indo-Soviet experiment for testing the Indianmhd generator channel section, designed and fabricated at the Bhabha Atomic Research Centre, Bombay, which was carried out at the U-02 facility in Moscow, USSR, in May 1980. The total test duration was 65 hours and included electrophysical tests and life tests under applied electric fields. The main purpose of the tests was to substantiate the physical concepts, computer codes, design features and special processing techniques involved in the development ofmhd generators for the Indian pilot plant at Tiruchirapalli. The experimental observations on the phenomena of heat transfer to the walls, gas dynamics in the channel, electrical characteristics of the generator and near-electrode processes including the analysis of arc spots correlate with the theoretical estimates based on present understanding of the physical processes occuring in similarmhd generators. The post-operational inspection of the channel section and extensive investigation of materials through microscopic analysis, chemical analysis and x-ray analysis are also reported in this paper. The joint test programme has clearly demonstrated the definite operating capability of the test section and has given sufficient information and encouragement for building better and improved channels for the future.     

Three dimensional solid-shell transition finite elements for heat conduction

This paper presents a finite element formulation for a special class of finite elements referred to as ‘Solid-Shell Transition Finite Elements’ for three dimensional heat conduction. The solid-shell transition elements are necessary in applications requiring the use of both three dimensional solid elements and the curved shell elements. These elements permit transition from the solid portion of the structure to the shell portion of the structure. A novel feature of the formulation presented here is that nodel temperatures as well as nodal temperature gradients are retained as primary variables. The element geometry is defined in terms of coordinates of the nodes as well as the nodal point normals for the nodes lying on the middle surface of the element. The temperature field with the element is approximated in terms of element approximation functions, nodal temperatures and nodal temperature gradients. The properties of the transition element are then derived using the weak formulation (or the quadratic functional) of the Fourier heat conduction equation in the Cartesian coordinate system and the element temperature approximation. The formulation presented here permits linear temperature distribution in the element thickness direction.

Convective boundaries as well as distributed heat flux is permitted on all six faces of the elements. Furthermore, the element formulation also permits internal heat generation and orthotropic material behavior. Numerical examples are presented firstly to illustrate the accuracy of the formulation and secondly to demonstrate its usefulness in practical application. Numerical results are also compared with the theoretical solutions.     

Nanostructured organic-inorganic photodiodes with high rectification ratio

High quality organic-inorganic heterojunction photodiodes based on nanostructured copper (II) phthalocyanine (CuPc) and intrinsic zinc oxide (i-ZnO) have been fabricated. The i-ZnO thin films/layers were grown by RF magnetron sputtering on clean indium tin oxide (ITO) coated glass substrates. These films have been characterized by optical absorption and field emission scanning electron microscopy (FESEM). CuPc thin films deposited at room temperature on i-ZnO have exhibited a change in their surface morphology with the post-deposition annealing temperature under normal atmosphere. The electrical dark conductivity and the photoconductivity of ITO/i-ZnO/CuPc/Au sandwich structures have been measured under various photoexcitation intensities using a xenon light source. The devices have shown excellent reproducibility of their electrical characteristics and high rectification ratios. The highest rectification ratio is nearly 831 calculated above the threshold voltage at room temperature for the sample annealed at 250?°C (i.e.?Pc 250). The effects of the annealing temperature of CuPc on the surface morphology, rectification ratio, and optical properties have been discussed.     

Preprogramming Floating Time of Liquid Marble

Non-sticking droplets wrapped with fine hydrophobic particles, namely liquid marbles, can be transported both on solid and water pool without an undesired spill of the inner encapsulated liquid. While the stimuli-responsive release of the inner liquid in the target area is proposed, the time-programmed release is not yet achieved. Herein, the hydrophobicity of nanoclay is modulated via a catalyst-free 1,4-conjugate addition reaction to form liquid marbles. This nanoclay liquid marble is robust and stable in air but collapses on the liquid pool with a specific lifetime. The lifetime of the liquid marble can be modulated over seconds to hours scale depending on the selection of chemically modulated wettability of the nanoclay. The critical mechanism of lifetime modulation is responsible for controlling the coalescence kinetics between the water pool and inner liquid by nanoclays’ high diffusion length and chemically varied water spreading potential. The NC liquid marble's programmable lifetime to ‘time-bomb’ type drug release and cascade chemical reaction is applied—without requiring any external intervention.     

An integrated genetic analysis microfluidic platform with valves and a PCR chip reusability method to avoid contamination

Clinical diagnostics and genomic research often require performing numerous genetic tests. While microfluidic devices provide a low-cost alternative to such demands, integrated microfluidic devices are fabricated using expensive technology not always affordable for single use. However, carryover cross-contamination (CXC) concerns (i.e. either false positive or false negative PCR data) in PCR chips prevent reuse, defying much of the advantages of miniaturized systems developed using expensive MEMS processing. In this work, we present an integrated and reusable PCR–CE glass microfluidic chip capable of multi-chamber PCR and sequential CE, with emphasis on a unique chip reusability approach to avoid CXC. For reliable PCR, the surface of the chamber is re-configured from its virgin hydrophilic (CA < 20°) to hydrophobic (CA > 110°) by silanization. To then extend this silanization method as a chip reusability technique, the silanization coating is ‘stripped and re-silanized’ (SRS) to create a fresh coating prior to each successive PCR run. Experimental confirmation of the effectiveness of SRS method in avoiding the CXC is demonstrated using plasmid DNA and HIV-1 infected DNA samples. We also present passive plug microvalves incorporated in the chip to enable fluid/vapor retention during the PCR and controlled fluid flow from the PCR chamber to the CE section for further analysis.     

Preferential grain growth and improved fatigue endurance in Sr substituted PZT thin films on Pt(1 1 1)/TiOx/SiO2/Si substrates

Pb(Zr_0.5Ti_0.5)O₃ and (Pb_0.9Sr_0.1)(Zr_0.5Ti_0.5)O₃ thin films were grown on Pt/TiO_x/SiO₂/Si substrates by chemical solution deposition. 10% Sr substituted PZT film showed high degree of (0 0 1) type preferential grain growth. Surface morphology revealed a clear correlation between preferred grain orientation and grain size. Room temperature dielectric constant was 1200 and 700 for the PZT and PSZT films, respectively. Dielectric loss reduced with Sr substitution. PZT film showed severe fatigue, and hence the polarization reduced to 20% of the initial value (24 μC/cm²) after 10⁸ cycles where as PSZT showed less fatigue, 75% of the initial polarization (12 μC/cm²) was retained after 10⁸ switching cycles.     

Preparation,structural, and characterizations of SnO2-coated TiNb2O7 anode materials for lithium-ion batteries

SnO₂-coated TiNb₂O₇ powders were synthesized via the solution coating method in the present research. The SnO₂ layers with a thickness of 3–5 nm were homogeneously coated on the surface of TiNb₂O₇ particles. TiNb₂O₇ coated with SnO₂ of 5 mol% with high Li⁺ diffusion coefficient delivered the discharge capacity of 319.5 mAh/g, which was 6.6% higher than that of the non-coated samples. The enhancement of capacity for the coated TiNb₂O₇ was owing to the low charge-transfer resistance of 17.5 Ω in contrary to the non-coated TiNb₂O₇ (27.8 Ω). SnO₂-coated TiNb₂O₇ possessed an improved capacity retention of 85.2% at 5 C after 100 cycles, superior to the non-coated TiNb₂O₇ (79.8%). On the other hand, the excessive amounts of SnO₂ coating led to the reduction in the capacity of the prepared samples. The excessive amounts of SnO₂ layers suppressed the Li⁺ diffusion and increased the charge-transfer resistance. The obtained results in this study indicated that coating of TiNb₂O₇ with appropriate amounts of SnO₂ significantly improved the electrochemical performance of TiNb₂O₇.