Low temperature preparation of nanocrystalline solid solution of strontium barium niobate by chemical process

Sr_xBa_1-xNb₂O₆ (with x = 0.4, 0.5 and 0.6) powders have been prepared by thermolysis of aqueous precursor solutions consisting of triethanolamine (TEA), niobium tartarate and, EDTA complexes of strontium and barium ions. Complete evaporation of the precursor solution by heating at ∼ 200°C, yields in a fluffy, mesoporous carbon rich precursor material, which on calcination at 750°C/2 h has resulted in the pure SBN powders. The crystallite and average particle sizes are found to be around 15 nm and 20 nm, respectively.     

Oxidation of Cr(III) in tannery sludge to Cr(VI): field observations and theoretical assessment

Sludge, soil and leachate samples collected from a chromium-contaminated tannery waste dumping site in Kanpur, India, were found to contain considerable amounts of Cr(VI), despite the fresh tannery sludge containing little or no Cr(VI). Literature reports suggested that dry Cr(III) precipitates could be converted to Cr(VI) when heated in the presence of oxygen. Also, Cr(III) in aqueous phase could be oxidized through interaction with manganese dioxide (MnO2) surface to Cr(VI). Measurement of manganese in the sludge samples collected from the site showed concentrations up to 0.6 mg/g. Based on equilibrium calculations, it was determined that both dry phase Cr(III) oxidation by atmospheric oxygen and aqueous phase Cr(III) oxidation by MnO2 surface were thermodynamically feasible. It was further suggested that in aqueous phase, manganese may act effectively as an electron transporter between Cr(III) and dissolved oxygen during Cr(III) oxidation, leading to regeneration of MnO2 solid phase. Further, as dissolved Cr(III) is oxidized, dissolution of Cr(OH3) will take place to maintain the equilibrium between the dissolved and solid phases of Cr(III). In the pH range of 3-10, and at oxygen partial pressure (P(O2)) of 10(-6) atm or higher, equilibrium conditions stipulate nearly complete conversion of Cr(III) to Cr(VI). At P(O2) of 10(-20) atm or lower, very little Cr(VI) is expected to be present under equilibrium conditions. In the intermediate P(O2) regions, incomplete dissolution of the Cr(OH3) solid phase and only partial conversion of chromium from +3 to the +6 oxidation state is expected, especially at lower pH values.     

Allergenic responses of red kidney bean (Phaseolus vulgaris cv chitra) polypeptides in BALB/c mice recognized by bronchial asthma and allergic rhinitis patients

Allergenicity potential of red kidney beans (Phaseolus vulgaris cv chitra) was assessed and attempts were made to identify the responsible proteins by pepsin digestibility assay and IgE immunoblotting. To evaluate allergenic potential, BALB/c mice were sensitized with red kidney bean proteins and levels of specific immunoglobulin, histamine, mast cell protease-1, cytokines and CCL-2 were measured. To confirm our findings in BALB/c, the studies were also extended to human subjects. Human sera collected from control subjects and allergic patients after skin prick test were used for IgE immunoblotting, measuring the levels of total and specific IgE and determining cross reactivity of red kidney bean with other legumes. Red kidney bean allergenic potential was evident by significant increase in specific IgE, IgG1, histamine, mast cell protease-1 and Th2 cytokine levels in comparison to control. Enhanced level of eosinophils in jejunum, prominent anaphylactic symptoms, and eruptive histopathological changes give indication towards red kidney beans allergenicity. IgE immunoblotting detected five protein components with molecular weights of approximately 170, 100, 43, 34 and 20 kDa. Red kidney bean proteins showed cross reactivity with peanut, soybean, chickpea and black gram. Finally, this work demonstrated that red kidney beans may induce allergic response in mice similar to human subjects, with identification of five clinically relevant allergenic protein components.     

Vitamin A fortification: Recent advances in encapsulation technologies

Vitamin A is an essential micronutrient whose deficiency is still a major health concern in many regions of the world. It plays an essential role in human growth and development, immunity, and vision, but may also help prevent several other chronic diseases. The total amount of vitamin A in the human diet often falls below the recommended dietary allowance of approximately 900–1000 $\mu$g/day for a healthy adult. Moreover, a significant proportion of vitamin A may be degraded during food processing, storage, and distribution, thereby reducing its bioactivity. Finally, the vitamin A in some foods has a relatively low bioavailability, which further reduces its efficacy. The World Health Organization has recommended fortification of foods and beverages as a safe and cost-effective means of addressing vitamin A deficiency. However, there are several factors that must be overcome before effective fortified foods can be developed, including the low solubility, chemical stability, and bioavailability of this oil-soluble vitamin. Consequently, strategies are required to evenly disperse the vitamin throughout food matrices, to inhibit its chemical degradation, to avoid any adverse interactions with any other food components, to ensure the food is palatable, and to increase its bioavailability. In this review article, we discuss the chemical, physical, and nutritional attributes of vitamin A, its main dietary sources, the factors contributing to its current deficiency, and various strategies to address these deficiencies, including diet diversification, biofortification, and food fortification.     

Design and implementation of qth quantile‐unbiased tr‐chart for monitoring times between events

The times between events control charts have been proposed in literature for statistical monitoring of high‐yield processes by observing the waiting times up to r ^th (r ≥ 1  ) non‐conforming items or defects. The average run length (ARL) is the most widely used performance measure to evaluate the chart's performance, but in recent years, it has been subjected to criticisms. Because the run length distribution is highly skewed and hence, the ARL is not necessarily a typical value of the run length. Thus, evaluation of the control chart based on ARL alone could be misleading. In this paper, the quantiles of run length distribution are considered, instead of ARL, to design the t_r ‐chart. Further, we eliminate the bias in q ^th quantile function of the t_r ‐chart for both the known and unknown parameter case. In particular, the MRL‐unbiased t_r ‐chart is discussed in detail and compared with the ARL‐unbiased t_r ‐chart. It is found that the MRL‐unbiased t_r ‐chart outperforms than the corresponding ARL‐unbiased chart in unknown parameter case. It is also found that the proposed chart requires less phase I observations than that of the earlier studies has been suggested.     

Low-Temperature Preparation of Nanocrystalline Lead Zirconate Titanate and Lead Lanthanum Zirconate Titanate Powders Using Triethanolamine

Nanocrystalline lead zirconate titanate (PZT) powders, with a Zr:Ti ratio of 60:40, have been prepared from a solution of triethanolamine (TEA) and Ti⁴⁺, Zr⁴⁺, and Pb²⁺ ions. The metal ions were in solution through complex formation with TEA. The soluble metal-ion–TEA complex formed the precursor material when it was completely dehydrated. Heat treatment of the precursor at 450°C resulted in single-phase PZT powders. The precursor and the heat-treated powders have been characterized by using thermal analysis and X-ray diffractometry (XRD) studies. The average particle size, as measured from X-ray line broadening and transmission electron microscopy studies, was ∼20 nm. PZT powders modified with 3 mol% of lanthanum (PLZT) also were prepared through this route and were investigated via XRD studies. The dielectric constants of the PZT and PLZT powders were 12475 and 11262, and their corresponding Curie temperatures were 362° and 315°C, respectively.     

Syntheses of nickel sulfides from 1,2-bis(diphenylphosphino)ethane nickel(II)dithiolates and their application in the oxygen evolution reaction

In this work, four heteroleptic Ni(II)dppe dithiolates complexes, [Ni(NED)(dppe)] (Ni-NED), [Ni(ecda)(dppe)] (Ni-ecda), [Ni(i-mnt)(dppe)] (Ni-i-mnt) and [Ni(cdc)(dppe)] (Ni-cdc) (dppe = 1,2-bis(diphenylphosphino)ethane; NED = 1-nitroethylene-2,2-dithiolate; ecda = 1-ethoxycarbonyl-1-cyanoethyelene-2,2-dithiolate; i-mnt = 1,1-dicyanoethylene-2,2-dithiolate and cdc = cyanodithioimidocarbonate), have been synthesized and characterized by analytical and spectroscopic techniques (Elemental analysis, vibrational, electronic absorption and multinuclear NMR spectroscopy). Structural characterization of all the four complexes by single crystal X-ray diffraction study suggests distortion in regular square planar geometry at Ni(II) center by coordination with two phosphorus of the dppe and two sulfur of the dithiolate ligands, respectively. The decomposition of all four complexes have been done to produce nickel sulfides and the resulting nickel sulfides have been utilized for electrocatalytic oxygen evolution reaction (OER). The nickel sulfide obtained by decomposing Ni-cdc shows best activity with overpotential η = 222 mV at j = 10 mA cm^?2 and a Tafel slope of 44.2 mV dec^?1 while other catalysts shows η > 470 mV at j = 5 mA cm^?2 and η > 600 mV at j = 10 mA cm^?2 at loading of 1.3 mg cm^?2.     

Accelerated Hot Corrosion Studies of D-Gun-Sprayed Cr<Subscript>2</Subscript>O<Subscript>3</Subscript>–50% Al<Subscript>2</Subscript>O<Subscript>3</Subscript> Coating on Boiler Steel and Fe-Based Superalloy

In the current investigation, Cr₂O₃–50% Al₂O₃ coating was deposited on ASTM-SA213-T-22 boiler steel and Fe-based superalloy Superfer 800H by D-gun spray process. The high-temperature corrosion performance of the coated as well as bare alloys was evaluated in Na₂SO₄–60%V₂O₅ molten salt, an aggressive environment at 900 °C under cyclic conditions. The kinetics of the corrosion were analyzed by the change in weight measurements which were taken after each cycle (i.e., 1-h heating in a tube furnace followed by 20-min cooling in ambient air) for a total period of 50 cycles. The X-ray diffraction and scanning electron microscopy/energy-dispersive X-ray analysis techniques were used for the analysis of corrosion products. During investigations, it was found that both the selected bare alloys have suffered intensive spallation in the form of removal of their oxide scales, which may be attributed to the formation of non-protective Fe₂O₃-dominated oxide scales, whereas the coated alloys have shown lesser weight gains along with better adhesiveness of the oxide scales with the substrate till the end of the experiment. The oxides of chromium and aluminum were the main phases revealed in the oxide scales of the coated specimens, which are reported to be protective against the hot corrosion.     

Dual biomarkers of anaerobic hydrocarbon degradation in historically contaminated groundwater

This study reports that ongoing in situ anaerobic hydrocarbon biodegradation at a manufactured gas plant impacted site is occurring, 9 years after the initial investigation. Groundwater samples from the site monitoring wells (MW) were analyzed for biomarkers by GC-MS, end-point PCR, and quantitative PCR (qPCR). Metabolic biomarkers included specific intermediates of anaerobic naphthalene and/or 2-methylnaphthalene degradation: 2-naphthoic acid (2-NA); 5,6,7,8-tetrahydro-2-NA (TH-2-NA); hexahydro-2-NA (HH-2-NA); and carboxylated-2-methylnaphthalene (MNA). The analogues of gene bssA, encoding alpha subunit of enzyme benzylsuccinate synthase, were used as a genetic biomarker. Results indicate 1-2 orders of magnitude higher abundance of total bacteria in the impacted wells than in the unimpacted wells. End-point PCR analysis of bssA gene, with degenerate primers, indicated the presence of hydrocarbon degrading bacteria within the plume. In qPCR analysis, using primers based on toluene-degrading denitrifying or sulfate-reducing/methanogenic bacteria, bssA genes were detected only in MW-24, located downstream from the source. Metabolic biomarkers were detected in multiple wells. The highest abundance of 2-NA (6.7 μg/L), TH-2-NA (2.6 μg/L), HH-2-NA, and MNA was also detected in MW-24. The distribution of two independent biomarkers indicates that the site is enriched for anaerobic hydrocarbon biodegradation and provides strong evidence in support of natural attenuation.