Inhomogeneous level splitting in Pr 2-x BixRu2O7

We report that Bi doping drives Pr 2-x BixRu2O7 from an antiferromagnetic insulator (x = 0) to a metallic paramagnet (x approximately 1) with a broad low T maximum in C/T. Neutron scattering reveals local low energy spin excitations (variant Planck's omega approximately 1 meV) with a spectrum that is unaffected by heating to k(B)T > variant Planck's omega. We show that a continuous distribution of splittings of the non-Kramers Pr3+ ground-state doublet such as might result from various types of lattice strain can account for all the data.     

Étude dans le système mercure solution acide des courbes I = f(E) relatives au dépôt et à la redissolution de traces de: Cu,Tl, Cd,Zn, Ni,Co, Fe

It is possible to redissolve in acid solution traces of Cu, Tl and Zu previously deposited on mercury without oxidising the mercury; the concentrations considered arcofthc order of 100y per ml of amalgam. Under the same conditions the redissolution of traces of Fe, Ni and Co can not be carried out without oxidation of the mercury.The constiuction in 1N H₂SO₄ medium of the curves I = f(E) for the Cu, Cd and Tl ions, the current I being negligible compared with the diffusion current, shows that. a. the variations in log I as a function of the potential E of the mercury or amalgam electrode are linear. b. the position of the curve log I — log a = f(E) is independent of the activity a of the element in solution or amalgam.Our experiments also show: 1° it is necessary to introduce a température coefficient for the coefficient relative to the overpotential of hydrogen on the mercury. 2° for cadmium, at weak current densities, a single electron is put into play in the case of deposition and in that of redissolving.     

Dosage gravimétrique rapide du béryllium dans les béryls

After attacking the beryl by fusing the powdered mineral with sodium peroxide and eliminating silica, beryllium is precipitated directly in the filtrate by mono-ammonium phosphate in the presence of complexon II or ethylene diamino-tetraacetic acid.Complexon II forms complexes and retains in the solution the other metals contained in beryl, but permits the quantitative precipitation of ammonium phosphate and beryllium which is calcined at 1000° and weighed out as beryllium pyrophosphate, Be2P2O7.     

Cinétique d'électrolyse de traces métalliques avec dégagement simultané d'hydrogène

The authors have determined, for analytical purposes, the influence of a certain number of factors affecting the kinetics of deposition of metallic traces on a platinum or mercury cathode when there is a simultaneous discharge of a large amount of hydrogen ions.The phenomenon of exaltation of the migration current of an ion in the presence of the simultaneous discharge of another chemical species allows an explanation of the parts played by the different factors considered.     

Infrared and Raman Spectra,Conformational Stability,Ab Initio Calculations,and Vibrational Assignments for Cyclopropyldifluorosilane

The infrared (3200–30 cm^–1) spectra of gaseous and solid Cyclopropyldifluorosilane, c-C₃H₅SiF₂H, and the Raman spectra (3200–20 cm^–1) of the liquid with quantitative depolarization values and the solid have been recorded. Both the syn (cis) and skew (gauche) conformers have been identified in the fluid phases, but only the syn conformer remains in the solid. Variable temperature (–55 to –100°C) studies of the infrared spectra of the sample dissolved in liquid xenon have been carried out. From these data, the enthalpy difference has been determined to be 73 ± 10 cm^–1 (209 ± 29 cal mol^–1), with the syn conformer being the more stable rotamer, which is at variance with the predictions from ab initio calculations. A complete vibrational assignment is proposed for both conformers based on infared band contours, relative intensities, depolarization values, and group frequencies. The vibrational assignments are supported by normal coordinate calculations utilizing the force constants from ab initio MP2/6-31G* calculations. Utilizing the frequencies of the silicon–hydrogen sketch, the rm Si—H bond distances of 1.474 and 1.472 Å have been obtained for the syn and skew conformers, respectively. Complete equilibrium geometries have been determined for both rotamers by ab initio calculations employing the 6-31G* and 6-311 +G** basis sets at levels of restricted Hartree-Fock (RHF) and/or Moller–Plesset (MP) to second order. The potential energy terms for the conformer interconversion have been obtained from the MP2/6-31G* calculation. The results are discussed and compared to those obtained for some similar molecules.     

γ-Secretase in Alzheimer’s disease

Alzheimer’s disease (AD) is caused by synaptic and neuronal loss in the brain. One of the characteristic hallmarks of AD is senile plaques containing amyloid β-peptide (Aβ). Aβ is produced from amyloid precursor protein (APP) by sequential proteolytic cleavages by β-secretase and γ-secretase, and the polymerization of Aβ into amyloid plaques is thought to be a key pathogenic event in AD. Since γ-secretase mediates the final cleavage that liberates Aβ, γ-secretase has been widely studied as a potential drug target for the treatment of AD. γ-Secretase is a transmembrane protein complex containing presenilin, nicastrin, Aph-1, and Pen-2, which are sufficient for γ-secretase activity. γ-Secretase cleaves >140 substrates, including APP and Notch. Previously, γ-secretase inhibitors (GSIs) were shown to cause side effects in clinical trials due to the inhibition of Notch signaling. Therefore, more specific regulation or modulation of γ-secretase is needed. In recent years, γ-secretase modulators (GSMs) have been developed. To modulate γ-secretase and to understand its complex biology, finding the binding sites of GSIs and GSMs on γ-secretase as well as identifying transiently binding γ-secretase modulatory proteins have been of great interest. In this review, decades of findings on γ-secretase in AD are discussed.Subject terms: Alzheimer''s disease, Alzheimer''s disease     

Cobalt ion-doped polyaniline,poly(N-methylaniline), and poly(N-ethylaniline): electrosynthesis and characterisation using electrochemical methods in acidic solutions

Cobalt ion (Co²⁺)-doped polyaniline (PANI-Co), poly(N-methylaniline) (PNMA-Co), and poly(N-ethylaniline) (PNEA-Co) films were synthesised electrochemically on a pencil graphite electrode (PGE) and their electrochemical properties were investigated for supercapacitor applications. The polymer film-coated electrodes (PGE/PANI-Co, PGE/PNMA-Co, and PGE/PNEA-Co) thus obtained were characterised by scanning electron microscopy (SEM) and different electrochemical methods. Cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS) measurements were employed in 0.1 M H₂SO₄ solution to calculate the specific capacitance (C _S) values of the electrodes. The maximum C _S of 192.94 F g^?1, 139.83 F g^?1, and 47.12 F g^?1 were achieved for PGE/PANI-Co, PGE/PNMA-Co, and PGE/PNEA-Co at 1 mV s^?1, respectively. On the other hand, the charge/discharge stability of the electrodes was analysed using the repeating chronopotentiometry (RCP) method. The RCP measurements indicate that the electrodes could be used as an electrode active material for low voltage supercapacitor applications.     

Interactions Between Helium Plasma Jets and Electrolytes at Different Driving Voltages

This study reports the effects of the driving voltage on interactions between plasma jets and electrolytes. Plasma jets over electrolytes, which were generated using five kinds of driving voltages, were characterized by distinct optical emissions from the gas region and the gas–liquid interface with unique electrical characteristics. The generated plasma jets over electrolytes resemble the characteristics of dielectric barrier discharges; the plasma–liquid interactions are affected by external driving voltages that vary the surface charge at the gas–liquid interface because of the conductive and dielectric nature of the electrolyte. The findings suggest that selecting an adequate driving voltage waveform is critical for specific applications utilizing plasma–liquid interactions.     

Structure and properties of dynamically cured EPDM and ionomer blends

The structure and properties of dynamically cured ethylene-propylene-diene terpolymer (EPDM) and ionomer blends have been studied. The blends were prepared in a laboratory internal mixer, where EPDM was cured under shear in the presence of ionomer with dicumyl peroxide (DCP) under different shear conditions. The effects of EPDM/ionomer compositions, DCP concentration and the intensity of shear mixing were investigated using capillary rheometer, differential scanning calorimeter (DSC) and scanning electron microscopy (SEM) techniques. Two kinds of poly(ethylene-co-methacrylic acid) ionomers containing different metal ions(Na⁺ and Zn⁺⁺) were compared and the effect of the metal ion type for neutralization was considered. The Zn-neutralized ionomer showed better miscibility with EPDM than the Na-neutralized ionomer. It is concluded from the rheological properties, crystallization behavior and morphology that the dynamically cured EPDM and Zn-ion ionomer blends show the behavior of a thermoplastic interpenetrating polymer network (IPN).