Determination of mercury by radiochemical displacement method

A radiochemical displacement method for the determination of micro amounts of Hg(II) has been developed. 65Zn was displaced from the Zn-1-(2-pyridylazo-2-naphthol) complex at pH 5 in borate buffers by Hg (II). 10-80 micrograms of mercury could be determined. Interference of various metal ions and methods for suppression have also been carried out.     

Positron annihilation studies of poly(N‐isopropyl acrylamide) gel in mixed solvents

Positron annihilation lifetime spectroscopy was used to characterize the reentrant volume‐phase‐transition behavior of poly(N‐isopropyl acrylamide) hydrogel in an ethanol/water mixed solvent. The polymer gel was synthesized with γ irradiation. The ortho‐positronium lifetime (τ₃) in the gel slowly increased with an increase in the ethanol content in the mixed solvent. τ₃ was not influenced by the volume phase transition. The ortho‐positronium intensity decreased with the collapse of the gel in an approximately 10% ethanol/water mixture. When swelled in pure ethanol, τ₃ initially increased with the solvent amount in the gel, showing the destruction of intramolecular hydrogen bonding and the relaxation of polymer chains. The lower critical solution temperature of the gel in the 10% ethanol/water mixture was lower than that in pure water, and τ₃ for various solvent contents showed behavior similar to that seen in pure solvent. © 2002 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 40: 1028–1036, 2002     

AMPK suppresses Th2 cell responses by repressing mTORC2

Allergic inflammation is a T helper 2 (Th2) cell-driven pathophysiological phenomenon, but the mechanism by which the metabolic cascade affects Th2 cell differentiation remains unclear. In this study, we investigated the roles of AMP-activated protein kinase (AMPK) and intracellular energy sensors in Th2 cell differentiation and the pathogenesis of allergic inflammation. Accordingly, T-cell-specific AMPK or Sirtuin 1 (Sirt1)-knockout mice were subjected to allergic inflammation, and their Th2 cell responses were investigated. The results demonstrated that inducing allergic inflammation in AMPK- and Sirt1-knockout mice increased Th2 cell responses and exacerbated allergic phenotypes. Furthermore, treatment with 5-aminoimidazole-4-carboxamide ribonucleotide (AICAR), an activator of AMPK, ameliorated allergic inflammation in mice. Mechanistically, our findings revealed that AMPK repressed mechanistic target of rapamycin complex 2 (mTORC2), which downregulated the expression of suppressor of cytokine signaling 5 (SOCS5) in CD4⁺ T cells. In addition, the loss of AMPK signaling reduced SOCS5 expression and increased interleukin-4-STAT6–GATA3 axis-mediated Th2 cell differentiation. Finally, the T-cell-specific deletion of Rictor, a member of mTORC2, in Sirt1^T-KO mice led to the reversal of allergic exacerbation to the level in control mice. Overall, our findings suggest that AMPK in CD4⁺ T cells inhibits the differentiation of Th2 cells by repressing mTORC2 and thus serves as a potential target for Th2 cell-associated diseases.Subject terms: Lymphocytes, Inflammation     

On the hydrothermal features of radiative Fe3O4–graphene hybrid nanofluid flow over a slippery bended surface with heat source/sink

Journal of Thermal Analysis and Calorimetry - The present investigation concentrates on the hydrothermal features of both hybrid nanofluid and usual nanofluid flow over a slippery permeable bent...     

An Observation on the Experimental Measurement of Dislocation Density

The common practice of ignoring the elastic strain gradient in measurements of geometrically necessary dislocation (GND) density is critically examined. It is concluded that the practice may result in substantial errors. Our analysis points to the importance of spatial variations of the elastic strain field in relation to its magnitude in inferring estimates of dislocation density from measurements.     

Trace element determination in high-purity aluminum clad samples by k 0-based internal monostandard instrumental neutron activation analysis

The k₀-based internal monostandard instrumental neutron activation analysis (IM-INAA) method was applied for quantification of trace impurities in seven high purity aluminum samples used as fuel cladding in a research reactor. Samples along with BCS CRM 182 (Si–Al alloy) were irradiated in high flux reactor neutrons for 10–15 h. In situ detection efficiency, needed in concentration calculation ratio by IM-INAA, was obtained using gamma rays of activation products produced in the samples. Elemental concentration ratios obtained with respect to Fe (used as internal monostandard) were converted to absolute concentrations by determining concentration of Fe by relative method of NAA. Concentrations of ten trace elements (Sc, Cr, Co, Zn, Ga, La, Ce, Sm, W and Hf) including major element Fe were determined in this work. The method used is non-destructive in nature and does not need multielement standards. Results of IM-INAA were compared with those obtained by relative method of INAA and inductively coupled plasma atomic emission spectrometry (ICP-AES). Details of methodologies and results obtained by all methods are discussed and compared in the paper.     

Trichloroisocyanuric Acid–KF as an Efficient Reagent for One-Pot Synthesis of Dialkylfluorophosphates from Dialkylphosphites

Trichloroisocyanuric acid–KF afforded dialkylfluorophosphates from dialkylphosphites at room temperature through a facile electrophilic–nucleophilic metathesis.     

Determination of trace concentrations of thorium in uranium oxide matrix by epithermal instrumental neutron activation analysis

An epithermal instrumental neutron activation analysis (EINAA) method using cadmium filter was standardized to determine trace concentrations of thorium in four samples of uranium oxide (U₃O₈) samples. Samples and thorium standards, wrapped with cadmium foil, were irradiated at a reactor neutron flux of about 10¹² cm^?2 s^?1. Radioactive assay was carried out using a Compton suppressed anticoincidence gamma ray spectrometer consisting of HPGe-BGO detectors coupled to MCA. Concentrations of thorium in these samples were found to be in the range of 15–72 mg kg^?1. EINAA results were validated by determining thorium concentrations in uranium matrix by standard addition method. EINAA results were compared with those obtained by two wet chemical methods namely ion chromatography (IC) and inductively coupled plasma atomic emission spectrometry (ICP-AES). The results obtained by the three methods were found to be in good agreement, indicating further validity of the proposed EINAA method.