Olfactory marker protein regulation of glucagon secretion in hyperglycemia

The olfactory marker protein (OMP), which is also expressed in nonolfactory tissues, plays a role in regulating the kinetics and termination of olfactory transduction. Thus, we hypothesized that OMP may play a similar role in modulating the secretion of hormones involved in Ca²⁺ and cAMP signaling, such as glucagon. In the present study, we confirmed nonolfactory α-cell-specific OMP expression in human and mouse pancreatic islets as well as in the murine α-cell line αTC1.9. Glucagon and OMP expression increased under hyperglycemic conditions. Omp knockdown in hyperglycemic αTC1.9 cells using small-interfering RNA (siRNA) reduced the responses to glucagon release and the related signaling pathways compared with the si-negative control. The OMP^lox/lox;GCG^cre/w mice expressed basal glucagon levels similar to those in the wild-type OMP^lox/lox mice but showed resistance against streptozotocin-induced hyperglycemia. The ectopic olfactory signaling events in pancreatic α-cells suggest that olfactory receptor pathways could be therapeutic targets for reducing excessive glucagon levels.Subject terms: Diabetes insipidus, Cell biology     

Fabrication of a nanohybrid of conjugated polymer nanoparticles and graphene oxide for biosensing of trypsin

Conjugated polymers containing triphenylamine group are synthesized via Suzuki coupling polymerization. Fluorescent‐conjugated polymer nanoparticles (CPN) are prepared by reprecipitation method using the newly synthesized conjugated polymer. CPN can be encapsulated with polyarginine by electrostatic interaction. The CPN modified with polyarginine exhibit excellent interaction with graphene oxide (GO) which is chemically modified with hydrophilic groups that possesses negative charge, which, in turn, induces the quenching of the fluorescence of CPN upon formation of CPN–GO nanohybrid. Upon exposure to trypsin, the quenched fluorescence is recovered by release of CPN from the nanohybrid, because trypsin cleaves the polyarginine linkage, resulting in weakening of interaction between CPN and GO. © 2014 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2014 , 52, 1898–1904     

Contrast in terahertz conductivity of phase-change materials

Time-domain terahertz spectroscopy was used to study the dielectric and conductive properties of thin films of four phase-change materials: GeTe, GeSb₂Te₄, GeSbTe₂, and AgInSbTe. Both amorphous and crystalline phases were studied, and the spectra were analyzed by a model including a harmonic oscillator and the Drude term. Spectra in the crystalline phase of AgInSbTe are dominated by free-carrier motion with a scattering time of 50 fs. In the Ge-containing compounds, we observed a phonon mode and a conductive contribution of free charge carriers with a much shorter scattering time. The conductivity appears to be linked to the distortions of the crystal unit cell from cubic symmetry.     

机器人柔性手臂的动力学有限元分析

本文将弹性动力学虚功原理推广到机器人柔性动力学,建立了计及关节弹性和关节阻尼的柔性手臂有限元动力学模型,模型中包括了非线性刚体运动和弹性变形间的耦合。文中还导出了手臂参考坐标系间的运动学递推关系。本文方法推演简单、计算效率高,能够用于具有任意复杂部件的柔性机器人动力学分析。     

Determination of trace element levels in polyethylene by instrumental neutron activation analysis

Elements Al, As, Au, Br, Cl, Co, Cr, Cu, Fe, Hg, K, La, Mn, Mo, Na, Sb, Sc, Sm, V, and Zn were determined by INAA in several brands and batches of high pressure polyethylene (PE) Bralen (Slovnaft Bratislava, Czechoslovakia). A large scatter of trace element contents was found in both granules and foils, indicating an inhomogeneous distribution for the majority of the above mentioned elements present as impurities in PE. Larger amounts of the elements Al, Mn, and Sb were found in foils than in granules. Blank values resulting from using of PE Bralen as a canning material for INAA were compared to trace element concentration in human hair samples, too.     

Determination of iodine in foodstuffs consumed in libya using instrumental and radiochemical neutron activation analysis

Iodine was determined in foodstuffs consumed in Libya employing two modes of NAA. The first mode was instrumental using short-time irradiation with epithermal neutrons behind a Cd shield (EINAA). The other mode utilized short-time irradiation with the reactor-pile neutrons followed by radiochemical separation (RNAA). The radiochemical separation procedure was based on the alkaline-oxidative fusion of samples and extraction of elemental iodine into chloroform. Separation yield determined using the radiotracer ¹³¹I was within the range of 90 to 95%. For quality control purposes, standard reference materials were analyzed in both modes employed. Using RNAA, a detection limit of ∼1 ng g⁻¹ could be obtained indicating superiority of the method in measuring ultra-trace levels of iodine. On the other hand, more than one order of magnitude higher detection limit did not allow sufficiently accurate determination of iodine in Libyan foodstuffs using EINAA.     

Simultaneous low-level determination of iodine and manganese in biological materials by radiochemical neutron activation analysis

A new RNAA procedure was developed for simultaneous determination of low levels of I and Mn in biological materials. The procedure is based on sample decomposition by alkaline-oxidative fusion in a mixture of Na₂O₂ + NaOH at 900°C followed by extraction of elementary iodine by chloroform. Subsequently, Mn is separated either by precipitation of hydrated MnO₂ or by extraction of the Mn-diethyldithiocarbamate complex in chloroform. The accuracy of the RNAA procedure developed was proven by analysis of several low-level biological reference materials. Detection limits of I and Mn achievable in both institutes and the degree of interference for the Mn determination due to ⁵⁶Fe(n,p)⁵⁶Mn reaction with fast neutrons are discussed.