Organic bistable memory device using MoO3 nanocrystal as a charge trapping center

Organic bistable memory devices (OBDs) with MoO₃ as a nanocrystal inside organic layer were developed and bistability of MoO₃ based OBDs was investigated. High on/off ratio over 200 was obtained at a low reading voltage of 1 V. MoO₃ OBDs could be electrically switched between high conductance state and low conductance state over more than 100 cycles and space charge limited conduction mechanism dominated switching behavior in MoO₃ OBDs.     

Hydrogen production from solid reactions between MAlH4 and NH4Cl

Solid reactions between alkali aluminum hydrides (MAlH₄, M = Li or Na) and NH₄Cl (at mole ratio 1:1) at 170 °C were investigated quantitatively using temperature programmed reaction (TPR), thermo-gravimetric analysis (TGA), differential scanning calorimetry (DSC) and x-ray diffraction (XRD). The release of 3 mol of H₂ from per mole of MAlH₄ was measured, corresponding to 5.6 wt.% H₂ capacity for the NaAlH₄/NH₄Cl system and 6.6 wt.% for LiAlH₄/NH₄Cl, respectively. By ball milling of the precursor compounds prior to the mixing, the reaction proceeded fast and NH₃ production as the by-product could be avoided. The quick solid reactions may be attributed to the low melting temperatures of MAlH₄ and the exothermic nature of the reactions. The reaction mechanism was also discussed.     

Allergenicity of hen's egg ovomucoid gamma irradiated and heated under different pH conditions

This study was conducted to evaluate the effect of a treatment combining gamma radiation and heating on the allergenic properties of hen's egg ovomucoid (OM) under basic pH conditions. OM solutions of 2.0 mg/ml with pHs of 7.0, 9.0, and 10.0 were gamma irradiated at 10 kGy, heated at 100 degrees C for 15 min, or both. Half of the treated pH 10.0 sample solution was restored to pH 7.4 by dialysis. OM solutions were tested by a competitive direct enzyme-linked immunosorbent assay formatted with immunoglobulin E from egg-hypersensitive patients. An equation was obtained for quantifying intact OM from the standard curve, and the detected concentration of intact OM was calculated. The concentration of intact OM decreased with irradiation or heating, and the rate of the decrease was higher for a basic pH condition than for the physiological condition. The combination of irradiation and heating was very effective in reducing the amount of intact OM regardless of the pH condition. After treatment, the restoration of the pH to 7.4 did not affect the concentration of OM. The results of this study indicate that a combination of irradiation and heating might be an effective method for reducing egg hypersensitivity resulting from OM.     

Synthesis of nanoporous calcium phosphate spheres using poly(acrylic acid) as a structuring unit

Calcium phosphate (CaP) spheres with nanopores were synthesized using poly(acrylic acid) (PAA) as the structuring unit. In this method, colloidal droplets of the PAA/Ca²⁺ complex were prepared by adding a Ca(NO₃)₂ solution to a PAA aqueous solution and then mixed with an (NH₄)₂HPO₄ solution, which allowed the nucleation and growth of CaP nanocrystals in the PAA matrix. Thereafter, the as-synthesized PAA/CaP spheres were heat-treated at 550 °C for 3 h to remove the PAA phase, followed by treatment in ammonium nitrate solution to remove the CaO phase formed as an impurity. The prepared CaP spheres showed a narrow size distribution with an average diameter of 146 ± 43 nm and nanopores formed via the removal of the CaO phase.     

A solvent extraction approach to recover acetic acid from mixed waste acids produced during semiconductor wafer process

Recovery of acetic acid (HAc) from the waste etching solution discharged from silicon wafer manufacturing process has been attempted by using solvent extraction process. For this purpose 2-ethylhexyl alcohol (EHA) was used as organic solvent. In the pre-treatment stage >99% silicon and hydrofluoric acid was removed from the solution by precipitation. The synthesized product, Na(2)SiF(6) having 98.2% purity was considered of commercial grade having good market value. The waste solution containing 279 g/L acetic acid, 513 g/L nitric acid, 0.9 g/L hydrofluoric acid and 0.030 g/L silicon was used for solvent extraction study. From the batch test results equilibrium conditions for HAc recovery were optimized and found to be 4 stages of extraction at an organic:aqueous (O:A) ratio of 3, 4 stages of scrubbing and 4 stages of stripping at an O:A ratio of 1. Deionized water (DW) was used as stripping agent to elute HAc from organic phase. In the whole batch process 96.3% acetic acid recovery was achieved. Continuous operations were successfully conducted for 100 h using a mixer-settler to examine the feasibility of the extraction system for its possible commercial application. Finally, a complete process flowsheet with material balance for the separation and recovery of HAc has been proposed.     

Effects of exponentially decaying and growing concentrations on particle size distribution from a scanning mobility particle sizer

Abstract

A scanning mobility particle sizer (SMPS) is one of the most widely used instruments to obtain size distribution for atmospheric particles. In an SMPS measurement, a voltage scanning process on a differential mobility analyzer is required, and it typically takes 30?s to 120?s to obtain one entire size distribution. A size distribution obtained by an SMPS measurement might have significant deviations from actual values due to the scanning process when the measured particle concentrations change over time. In this study, we introduce an analytical approach for estimating particle size distribution under exponentially decaying and growing particle concentrations. The analytical SMPS results are validated by performing experiments using exponentially decaying particle concentrations under the same conditions. Furthermore, the effects of a decay parameter, initial size distribution, and scan time are evaluated, and the deviations from actual (real or true) size distributions obtained by an exact solution are analyzed. Geometric mean diameters and standard deviations of the size distributions from SMPS results increase or decrease with exponentially decaying or growing concentrations, respectively, and total concentrations estimated by the analytical SMPS approach are significantly underestimated or overestimated compared to real total concentrations. While SMPS measurements have been widely employed in various applications such as atmospheric particle characterization in highly variable particle concentrations versus time, very few studies on the influence of changing concentrations on SMPS measurements have been conducted. Therefore, the introduced analytical approach and findings provide valuable insight into the importance of accurate SMPS measurements with changing particle concentrations.

Copyright © 2020 American Association for Aerosol Research     

Molecular Weight Dependent Glucose Lowering Effect of Low Molecular Weight Chitosan Oligosaccharide (GO2KA1) on Postprandial Blood Glucose Level in SD Rats Model

This research investigated the effect of enzymatically digested low molecular weight (MW) chitosan oligosaccharide on type 2 diabetes prevention. Three different chitosan oligosaccharide samples with varying MW were evaluated in vitro for inhibition of rat small intestinal α-glucosidase and porcine pancreatic α-amylase (GO2KA1; <1000 Da, GO2KA2; 1000–10,000 Da, GO2KA3; MW > 10,000 Da). The in vitro results showed that all tested samples had similar rat α-glucosidase inhibitory and porcine α-amylase inhibitory activity. Based on these observations, we decided to further investigate the effect of all three samples at a dose of 0.1 g/kg, on reducing postprandial blood glucose levels in Sprague-Dawley (SD) rat model after sucrose loading test. In the animal trial, all tested samples had postprandial blood glucose reduction effect, when compared to control, however GO2KA1 supplementation had the strongest effect. The glucose peak (C_max) for GO2KA1 and control was 152 mg/dL and 193 mg/dL, respectively. The area under the blood glucose-time curve (AUC) for GO2KA1 and control was 262 h mg/dL and 305 h mg/dL, respectively. Furthermore, the time of peak plasma concentration of blood glucose (T_max) for GO2KA1 was significantly delayed (0.9 h) compared to control (0.5 h). These results suggest that GO2KA1 could have a beneficial effect for blood glucose management relevant to diabetes prevention in normal and pre-diabetic individuals. The suggested mechanism of action is via inhibition of the carbohydrate hydrolysis enzyme α-glucosidase and since GO2KA1 (MW < 1000 Da) had higher in vivo effect, we hypothesize that it is more readily absorbed and might exert further biological effect once it is absorbed in the blood stream, relevant to blood glucose management.     

Change of an egg allergen in a white layer cake containing gamma-irradiated egg white

This study was conducted to evaluate the reduction of an egg allergen in a cake containing gamma-irradiated egg white. A white layer cake was manufactured by a commercial formula with 10- or 20-kGy-irradiated egg white. Enzyme-linked immunosorbent assays (ELISAs) with immunoglobulin (Ig) E from egg-allergic patients and with rabbit anti-ovalbumin IgG were used to identify and quantify ovalbumin (OVA) in the samples. Concentrations of native OVA detected by IgE and IgG in the control were 432.88 and 375.46 microg/g sample, respectively. However, native OVA in samples with 10- and 20-kGy-irradiated egg white was detected at low concentrations (14.27 and 8.78 microg/g, respectively) by IgE (P < 0.05); IgG recognized OVA more often in 10- and 20-kGy samples than in controls. Conformational cleavage of OVA by irradiation could explain the IgG result. The results appear to suggest that irradiating egg white might reduce its allergenicity, which could be used in the production of baked goods of reduced allergenicity.     

Peroxisome proliferator-activated receptor alpha controls the hepatic CYP4A induction adaptive response to starvation and diabetes

The hepatic CYP4A enzymes are important fatty acid and prostaglandin omega-hydroxylases that are highly inducible by fibric acid hypolipidemic agents and other peroxisome proliferators. Induction of the CYP4A enzymes by peroxisome proliferators is mediated through the nuclear peroxisome proliferator-activated receptor alpha (PPARalpha). Fatty acids have recently been identified as endogenous ligands of PPARalpha, and this receptor has been implicated in the regulation of lipid homeostasis. In the present report we characterized the induction of the hepatic CYP4A genes in rats during the altered lipid metabolism associated with starvation and diabetes. The mRNA levels of CYP4A1, CYP4A2, and CYP4A3 were induced 7-17-fold in the livers of fasted animals and 3-8-fold in the livers of diabetic animals. This was accompanied by corresponding changes in CYP4A protein levels and arachidonic and lauric acid omega-hydroxylase activity. Interestingly, feeding animals after the fasting period caused as much as an 80% suppression of CYP4A mRNA levels, whereas CYP4A protein levels and functional activity returned to control values. A second PPARalpha-responsive gene, acyl-CoA oxidase, was also induced in rat liver by diabetes and fasting. By using PPARalpha-deficient mice, we unambiguously demonstrated that PPARalpha is strictly required for hepatic CYP4A induction by starvation and diabetes. Similarly, induction of hepatic thiolase and bifunctional enzyme also required expression of PPARalpha. This represents the first evidence for the pathophysiologically induced activation of a nuclear receptor.     

Paricalcitol Improves Hypoxia-Induced and TGF-β1-Induced Injury in Kidney Pericytes

Recently, the role of kidney pericytes in kidney fibrosis has been investigated. This study aims to evaluate the effect of paricalcitol on hypoxia-induced and TGF-β1-induced injury in kidney pericytes. The primary cultured pericytes were pretreated with paricalcitol (20 ng/mL) for 90 min before inducing injury, and then they were exposed to TGF-β1 (5 ng/mL) or hypoxia (1% O₂ and 5% CO₂). TGF-β1 increased α-SMA and other fibrosis markers but reduced PDGFRβ expression in pericytes, whereas paricalcitol reversed the changes. Paricalcitol inhibited the TGF-β1-induced cell migration of pericytes. Hypoxia increased TGF-β1, α-SMA and other fibrosis markers but reduced PDGFRβ expression in pericyte, whereas paricalcitol reversed them. Hypoxia activated the HIF-1α and downstream molecules including prolyl hydroxylase 3 and glucose transporter-1, whereas paricalcitol attenuated the activation of the HIF-1α-dependent molecules and TGF-β1/Smad signaling pathways in hypoxic pericytes. The gene silencing of HIF-1α vanished the hypoxia-induced TGF-β1, α-SMA upregulation, and PDGFRβ downregulation. The effect of paricalcitol on the HIF-1α-dependent changes of fibrosis markers was not significant after the gene silencing of HIF-1α. In addition, hypoxia aggravated the oxidative stress in pericytes, whereas paricalcitol reversed the oxidative stress by increasing the antioxidant enzymes in an HIF-1α-independent manner. In conclusion, paricalcitol improved the phenotype changes of pericyte to myofibroblast in TGF-β1-stimulated pericytes. In addition, paricalcitol improved the expression of fibrosis markers in hypoxia-exposed pericytes both in an HIF-1α-dependent and independent manner.