Fabrication and characteristics of tapes and test magnets made from Ag-Clad Bi-2223 superconductors

Pb_0.4Bi_1.8Sr₂Ca_2.2Cu₃O_x (Bi-2223) precursor powder was prepared by a solid-state reaction of carbonates and oxides of lead, bismuth, strontium, calcium, and copper, and the powder was then used to fabricate silver-clad tapes by the powder-in-tube technique. Transport critical current density (J_c) values>4×10⁴ A/cm² at 77K and 2×10⁵ A/cm² at 4.2 and 27K have been achieved in short tape samples. Long lengths of tape were tested by winding them into pancake coils. Recently, we fabricated a test magnet by stacking ten pancake coils, each containing three 16m lengths of rolled tape, and tested it at 4.2, 27 and 77K. A maximum generated field of 2.6 T was measured in zero applied field at 4.2K and the test magnet generated significant self-field in background fields up to 20 T. The results are discussed in this paper.     

Stability of Fe3+ — VO defect pairs in polycrystalline Pb(Ti,Zr)O3

The intensity of the EPR signal with g = 5.985 arising from a ferric ion — oxygen vacancy defect pair (Fe³⁺ — V_O) in PbTiO₃, varies with the extent of PbO nonstoichiometry at constant Fe³⁺ content due to an increased oxygen vacancy concentration. In PZT solid solutions, the signal intensity decreases with an increase in Zr. A lower intensity is also noticed for Fe³⁺ — V_O signals in PbZrO₃. This behaviour is explained on the basis of PbO nonstoichiometry arising from independent Pb- and O-vacancies as well as the randomly distributed crystallographic shear (CS) plane defects. The contribution to PbO nonstoichiometry from CS planes is larger in high zirconium compositions of PZT.     

Process Technology for the Production of Micronutrient Rich Red Palm Olein

Crude palm oil (CPO) is the richest natural source of carotenes that are destroyed in the conventional processing. There is a growing demand for nutritional products containing bioactive constituents externally fortified or preserved through modified process. A commercially viable process for the production of red palm olein (RPOn) rich in carotenes, tocols and sterols has been developed at pilot scale. The process developed involved neutralization of CPO followed by crystallization at controlled rate of cooling and deodorization of the resultant neutralized and winterized palm olein (WPOn) under controlled conditions of temperature and high vacuum. Analytical data related to micronutrients at each process step was monitored. The RPOn thus produced had not more than 0.25% of free fatty acids (FFA) and it retained more than 80% of the carotenes, about 85% of tocols and 65% of sterols originally present in the CPO. The physico-chemical characteristics of RPOn revealed that it is nutritionally of superior quality compared to that of the commercial refined bleached deodorized (RBD) palm olein currently available in the market. The carotenes, tocols and sterols profile of RPOn by HPLC showed that they were retained in their natural forms.     

Zero-<Emphasis Type="Italic">trans</Emphasis> shortening using palm stearin and rice bran oil

Several pilot-scale trials reported in this paper, using palm stearin-rice bran oil (PS-RBO) blends, obviously did not contain trans FA (TFA), whereas the commercial products were found to contain 18–27% TFA. The effects of processing conditions such as rate of agitation, crystallization temperature, and composition of the blends on the crystal structure of shortenings were studied. The products were evaluated for their physicochemical characteristics using DSC, X-ray diffraction (XRD), HPLC, and FTIR techniques. The formulation containing 50% PS and 50% RBO showed melting and cooling characteristics similar to those of hydrogenated commercial “vanaspati” samples. Analysis of the FA composition revealed that the formulated shortenings contained 15–19% C_18∶2 PUFA. Tocopherol and tocotrienol contents of the experimental shortenings were in the range of 850–1000 ppm with oryzanol content up to 0.6%. XRD studies demonstrated that the crystal form in the shortenings was predominantly the most stable β′ form, and there was less of the undesirable β form.     

Lipid metabolism of acetate-1-14C by leukocytes from dogs fed an arteriosclerosis-inducing diet

Dogs were maintainedoon a control ration or on a semisynthetic diet, containing 5% cholesterol and 16% hydrogenated coconut oil, known to induce hyperlipemia and arteriosclerosis. Circulating leukocytes isolated from dogs fed the coconut oil containing diet were shown to incorporate 50% more radioactivity into lipids than control leukocytes when incubated with acetate-1-¹⁴C. This increase, expressed as dpm/mg of leukocyte DNA, was not specific for any particular lipid since the distribution of radioactivity between neutral lipids and phospholipids, as well as among their subfractions, was the same regardless of the diet fed. The labeling patterns observed suggest that leukocyte fatty acid synthesis from acetate occurs predominantly, and perhaps exclusively, by the chain elongation pathway.     

Photonic textile fibers

The characterization of the emission from nylon fibers containing laser dyes and TIO(2) nanoparticle scatterers indicates laser behavior with linewidths as low as 4 nm in 200- to 800-μm fibers. These materials can be used to produce lasing textiles, which can be used to produce photonic codes for a variety of civilian and military applications.     

A magnetic bead-based DNA extraction and purification microfluidic device

This article introduces a novel magnetic bead-based DNA extraction and purification device using active magnetic mixing approach. Mixing and separation steps are performed using functionalised superparamagnetic beads suspended in cell lysis buffer in a circular chamber that is sandwiched between two external magnetic coils. Non-uniform nature of magnetic field causes temporal and spatial distribution of beads within the chamber. This process efficiently mixes the lysis buffer and whole blood in order to extract DNA from target cells. Functionalized surface of the magnetic beads then attract the exposed DNA molecules. Finally, DNA-attached magnetic beads are attracted to the bottom of the chamber by activating the bottom magnetic coil. DNA molecules are extracted from magnetic beads by washing and re-suspension processes. In this study, a circular PMMA microchamber, 25 μL in volume, 500 μm in depth and 8 mm in diameter was fabricated to purify DNA from spiked bacterial cell cultures into the whole blood sample using Promega Magazorb DNA extraction kit. The lysis efficiency was evaluated using a panel of Gram-positive (Bacillus subtilis) and Gram-negative (Escherichia coli) bacterial cells cultures into the blood sample to achieve approximately 100,000 copy levels inside the chip. Manufacturer’s standard extraction protocol was modified to a more simplified process suitable for chip-based extraction. The lysis step was performed using 5 min incubation at 56 °C followed by 5 min incubation at room temperature for binding process. Temperature rise was generated and maintained by the same external magnetic coils used for active mixing. The yield/purity and recovery levels of the extracted DNA were evaluated using quantitative UV spectrophotometer and real-time PCR assay, respectively. Real-time PCR results indicated efficient chip-based bacterial DNA extraction using modified extraction protocol comparable to the standard bench-top extraction process.     

Defect structure of acceptor-doped calcium titanate at elevated temperatures

The defect structure of acceptor (Al or Cr)-doped polycrystalline calcium titanate was investigated by measuring the oxygen partial pressure dependence (at 10° to 10–18 atm) of the electrical conductivity at 1000 and 1050° C. The observed electrical conductivity data were proportional to for the oxygen pressure range < 10^–10 atm and proportional to for the oxygen pressure range ( 10^–7 atm. The conductivity values were observed to increase with the acceptor concentration in the p-type region with the shift in the conductivity minima towards lower oxygen partial pressure. The absolute value of the electrical conductivity in the acceptor-doped samples were lower in the n-type region compared to the values in the undoped CaTiO₃. Aluminium and chromium were found to be equally effective in acting as acceptor impurities in CaTiO₃. The defect chemistry of CaTiO₃ is dominated by the added acceptor impurities for the entire oxygen partial pressure range used in this investigation.     

The study of the performance of an electrostatic valve used forbulk transport of particulate materials

In many mass transfer processes, it is necessary to accurately control the flow of particulate materials. Commonly used mechanical valves have serious drawbacks which can be overcome by the use of electric field, which can locally originate interparticle compressive forces throughout the bulk material as a result of the greatly enhanced electric field and charge flux densities occurring at the contact points between the particles or between the particles and the boundary. Such interparticle electroclamping forces can be established by applying an electric potential gradient between a separated pair of conductive electrode grids placed perpendicularly across the flow within the duct where the material flows. The flow control of particulate materials is, thus, achieved using no moving parts. When an electric field is applied to a packed bed of particulate solids, several types of electrical force (electrostatic attractive force, dielectrophoretic force, and electroclamping force) may be generated, depending on the bulk and surface resistivities of the particle, the geometry of the electrodes, as well as the nature of the applied field. The influence of the electrode geometry on flow control was investigated using computer modeling of the potential based on finite element techniques. Furthermore, the effect of the applied field with respect to the magnitude, frequency, pulsewidth, and pulse shape on flow controllability was experimentally investigated. The influence of the moisture content of turnip seeds on flow controllability and specific charge was investigated, and the results obtained are discussed in this paper     

Density functional theory and machine learning guided search for RE2Si2O7 with targeted coefficient of thermal expansion

Density functional theory (DFT) calculations and machine learning (ML) methods are used to establish a relationship between the crystal structures of rare-earth (RE) disilicates (RE₂Si₂O₇) and their coefficient of thermal expansion (CTE). The DFT total energy data predict the presence of several energetically competing crystal structures, which is rationalized as one of the reasons for observing polymorphism. An ensemble of support vector regression models is trained to rapidly predict the CTE as a function of RE₂Si₂O₇ crystal chemistry. Experiments subsequently validated the structure and CTE predictions for Sm₂Si₂O₇.