Hyperfine induced 1s2s ^1S_0 \to 1s^2 ^1S_0 M1 transition of He-like ions

Hyperfine induced 1s2s ^1S_0 \to 1s^2 ^1S_0 M1 transition probabilities of He-like ions have been calculated from relativistic configuration interaction wavefunctions including the frequency independent Breit interaction and QED effects. Present results for {$^{151}$}Eu and {$^{155}$}Gd are in good agreement with previous calculations [Phys. Rev. A {\bf 63}, 054105 (2001)]. Electronic data are given in terms of a general scaling law in $Z$ that, given isotopic nuclear spin and magnetic moment, allows hyperfine induced decay rates to be estimated for any isotope. The results should be helpful for future experimental investigations on QED and parity non-conservation effects.Comment: 9 pages, 2 figure

Effects of the electron correlation and Breit and hyperfine interactions on the lifetime of the 2p5^53s states in neutral neon

In the framework of the multiconfiguration Dirac-Hartree-Fock method, we investigate the transition properties of four excited states in the $2p^53s$ configuration of neutral neon. The electron correlation effects are taken into account systematically by using the active space approach. The effect of higher-order correlation on fine structures is shown. We also study the influence of the Breit interaction and find that it reduces the oscillator strength of the $^3P^o_1 - ^1S_0$ transition by 17%. It turns out that the inclusion of the Breit interaction is essential even for such a light atomic system. Our ab initio calculated line strengths, oscillator strengths and transition rates are compared with other theoretical values and experimental measurements. Good agreement is found except for the $^3P^o_2 - ^1S_0$ M2 transition for which discrepancies of around 15% between theories and experiments remain. In addition, the impact of hyperfine interactions on the lifetimes of the $^3P^o_0$ and $^3P^o_2$ metastable states is investigated for the $^{21}$Ne isotope (I=3/2). We find that hyperfine interactions reduce the lifetimes drastically. For the $^3P^o_0$ state the lifetime is decreased by a factor of 630.Comment: Accepted by Phys. Rev.

catena-Poly[[tetra­kis­(1H-pyrazole-κN 2)copper(II)]-μ-hexa­fluoridosilicato-κ2 F:F′]

In the title one-dimensional coordination polymer, [Cu(SiF6)(C3H4N2)4]n, the CuII atom is coordinated by two hexafluoridosilicate F atoms and four pyrazole N atoms in a distorted trans-CuF2N4 octa­hedral environment. The dihedral angle between the planes of the pyrazlole rings in the asymmetric unit is 74.4 (3)°. The hexa­fluoridosilicate dianion acts as a bridging ligand, connecting the CuII atoms into a [1-10] chain. The Cu and Si atoms lie on special positions with 2/m site symmetry. In the crystal, intra­chain N—H⋯F hydrogen bonds occur and weak C—H⋯F inter­actions link the chains

Non-eutectic phase change materials for cold thermal energy storage

Phase change materials provide high-density thermal energy storage and a wide range of temperatures are required to meet different storage applications for cascaded thermal storage systems. Thus, non-eutectic phase change materials, namely aqueous ethylene glycol and ethanol solutions, are investigated in this paper for potential applications in high-grade cold thermal energy storage applications. The aqueous solutions of varying concentrations are characterized by differential scanning calorimetry and thermal response measurements for bulk PCMs. The phase change materials are able to meet a wide range of storage temperatures with no issue of phase separation. Graphene oxide powder of 1 wt.% is added as a stable nano-filler to enhance thermal conductivity and reduce supercooling degrees. Through thermal response measurements, improvements of charging times in the phase change of aqueous ethylene glycol and ethanol solutions are observed.NRF (Natl Research Foundation, S’pore)Published versio

Glomerular-specific protein kinase C-β-induced insulin receptor substrate-1 dysfunction and insulin resistance in rat models of diabetes and obesity

Insulin resistance has been associated with the progression of chronic kidney disease in both diabetes and obesity. In order to determine the cellular mechanisms contributing to this, we characterized insulin signaling in renal tubules and glomeruli during diabetic and insulin-resistant states using streptozotocin-diabetic and Zucker fatty-insulin-resistant rats. Compared with nondiabetic and Zucker lean rats, the insulin-induced phosphorylation of insulin receptor substrate-1 (IRS1), Akt, endothelial nitric oxide synthase, and glycogen synthase kinase 3α were selectively inhibited in the glomeruli but not in the renal tubules of both respective models. Protein, but not mRNA levels of IRS1, was decreased only in the glomeruli of streptozotocin-diabetic rats likely due to increased ubiquitination. Treatment with the protein kinase C-β inhibitor, ruboxistaurin, enhanced insulin actions and elevated IRS1 expression. In glomerular endothelial cells, high glucose inhibited the phosphorylation of Akt, endothelial nitric oxide synthase, and glycogen synthase kinase 3α; decreased IRS1 protein expression and increased its association with ubiquitin. Overexpression of IRS1 or the addition of ruboxistaurin reversed the inhibitory effects of high glucose. Thus, loss of insulin's effect on endothelial nitric oxide synthase and glycogen synthase kinase 3α activation may contribute to the glomerulopathy observed in diabetes and obesity

Protective Effects of GLP-1 on Glomerular Endothelium and Its Inhibition by PKCβ Activation in Diabetes

To characterize glucagon-like peptide (GLP)-1 signaling and its effect on renal endothelial dysfunction and glomerulopathy. We studied the expression and signaling of GLP-1 receptor (GLP-1R) on glomerular endothelial cells and the novel finding of protein kinase A–dependent phosphorylation of c-Raf at Ser259 and its inhibition of angiotensin II (Ang II) phospho–c-Raf(Ser338) and Erk1/2 phosphorylation. Mice overexpressing protein kinase C (PKC)β2 in endothelial cells (EC-PKCβ2Tg) were established. Ang II and GLP-1 actions in glomerular endothelial cells were analyzed with small interfering RNA of GLP-1R. PKCβ isoform activation induced by diabetes decreased GLP-1R expression and protective action on the renal endothelium by increasing its degradation via ubiquitination and enhancing phospho–c-Raf(Ser338) and Ang II activation of phospho-Erk1/2. EC-PKCβ2Tg mice exhibited decreased GLP-1R expression and increased phospho–c-Raf(Ser338), leading to enhanced effects of Ang II. Diabetic EC-PKCβ2Tg mice exhibited greater loss of endothelial GLP-1R expression and exendin-4–protective actions and exhibited more albuminuria and mesangial expansion than diabetic controls. These results showed that the renal protective effects of GLP-1 were mediated via the inhibition of Ang II actions on cRaf(Ser259) and diminished by diabetes because of PKCβ activation and the increased degradation of GLP-1R in the glomerular endothelial cells

Prediction of Skin Sensitization with a Particle Swarm Optimized Support Vector Machine

Skin sensitization is the most commonly reported occupational illness, causing much suffering to a wide range of people. Identification and labeling of environmental allergens is urgently required to protect people from skin sensitization. The guinea pig maximization test (GPMT) and murine local lymph node assay (LLNA) are the two most important in vivo models for identification of skin sensitizers. In order to reduce the number of animal tests, quantitative structure-activity relationships (QSARs) are strongly encouraged in the assessment of skin sensitization of chemicals. This paper has investigated the skin sensitization potential of 162 compounds with LLNA results and 92 compounds with GPMT results using a support vector machine. A particle swarm optimization algorithm was implemented for feature selection from a large number of molecular descriptors calculated by Dragon. For the LLNA data set, the classification accuracies are 95.37% and 88.89% for the training and the test sets, respectively. For the GPMT data set, the classification accuracies are 91.80% and 90.32% for the training and the test sets, respectively. The classification performances were greatly improved compared to those reported in the literature, indicating that the support vector machine optimized by particle swarm in this paper is competent for the identification of skin sensitizers

DNA linking number change induced by sequence-specific DNA-binding proteins

Sequence-specific DNA-binding proteins play a key role in many fundamental biological processes, such as transcription, DNA replication and recombination. Very often, these DNA-binding proteins introduce structural changes to the target DNA-binding sites including DNA bending, twisting or untwisting and wrapping, which in many cases induce a linking number change (ΔLk) to the DNA-binding site. Due to the lack of a feasible approach, ΔLk induced by sequence-specific DNA-binding proteins has not been fully explored. In this paper we successfully constructed a series of DNA plasmids that carry many tandem copies of a DNA-binding site for one sequence-specific DNA-binding protein, such as λ O, LacI, GalR, CRP and AraC. In this case, the protein-induced ΔLk was greatly amplified and can be measured experimentally. Indeed, not only were we able to simultaneously determine the protein-induced ΔLk and the DNA-binding constant for λ O and GalR, but also we demonstrated that the protein-induced ΔLk is an intrinsic property for these sequence-specific DNA-binding proteins. Our results also showed that protein-mediated DNA looping by AraC and LacI can induce a ΔLk to the plasmid DNA templates. Furthermore, we demonstrated that the protein-induced ΔLk does not correlate with the protein-induced DNA bending by the DNA-binding proteins