Improving the sensitivity of a humidity sensor based on fiber bend coated with a hygroscopic coating

A highly sensitive all-fiber humidity sensor is demonstrated. The sensor behaves as a humidity dependent optical switch between 85% and 90% RH. This sensor also offers the advantages of simple structure and low cost and its response is fast and reversible in nature. The typical humidity response of the sensor is suitable for using it as a human breath rate monitor.     

Polythermal section Sn4P3-Sn4As3

The T-x diagram of the polythermal section Sn₄P₃-Sn₄As₃ of the Sn-P-As system was constructed using the results of X-ray powder diffraction and differential thermal analyses. A continuous series of solid solutions (Sn₄P₃) _x (Sn₄As₃)_{1 ? x} was found to exist. The section is not quasi-binary; in a Sn₄As₃-rich region, this section intersects the peritectic part of the three-phase volume (L + SnAs + α) of the ternary diagram.     

Solid solubility in the Bi-Sb-As ternary system

The existence region of the ternary solid solution in the Bi-Sb-As system is studied using DTA, X-ray powder diffraction, and thermodynamic calculations. The alloys of this system have positive nonideality, which is mainly due to the elastic component of the enthalpy of mixing. The nonideality increases as the antimony concentration in the sample decreases, and finally brings about the instability and decay of the solid solution. It is shown experimentally that complete miscibility is observed at high antimony concentrations, when the antimony atom fraction is higher than or equal to 0.75–0.80.     

Spectral Asymptotics for Higher-Order Ordinary Differential Equations

This paper gives one-term componentwise asymptotics for theM and spectral matrices of a self-adjoint realisation of aneven-order ordinary differential expression. The underlyinginterval is assumed to have at least one regular endpoint, andthe boundary conditions are supposed to be separated. Furthermore,the weight function and the reciprocal of the highest-ordercoefficient are supposed to be of regular variation at the regularendpoint, in the sense of Bingham, Goldie and Teugels. 1991Mathematics Subject Classification: 34B24, 34E05.     

<Superscript>1</Superscript>H and <Superscript>7</Superscript>Li NMR in defect cobaltite Li<Subscript>0.6</Subscript>CoO<Subscript>2</Subscript>

Within a temperature range of 120–330 K, ⁷Li NMR spectra in Li_0.6CoO₂ are obtained. It is shown that as the temperature increases, both smooth and stepwise variation of ⁷Li NMR contact shifts occurs. The observed effects are explained by the occupation of the excited levels of cobalt ions. The stepwise change of the resonance line width depending on the temperature is revealed. It is driven by the features of the diffusive motion of lithium ions. The calculation of the ¹H NMR line shape provides the determination of the ratio of one-, two-, and three-spin proton clusters in Li_0.6CoO₂·xH₂O.     

A Method for the Quantitative Determination of the Total Flavonoid Content of Moringa Leaves (Moringa oleifera)

Moscow University Chemistry Bulletin - A differential spectrophotometry method for quantitation of the total flavonoid content of moringa leaves (Moringa oleifera) using aluminum chloride is...     

Gradient HPLC Separation of Alkylphosphonic Acids on a Hypercarb Porous Graphitic Carbon Adsorbent with an Aqueous Formic Acid Solution as the Mobile Phase

An approach to the gradient HPLC separation of alkylphosphonic acids on a Hypercarb porous graphitic carbon adsorbent with an aqueous formic acid solution as a mobile phase is proposed. Analytes were detected using a quadrupole mass spectrometer. To increase the retention of the analytes, the chromatographic column was washed with water before the injection of a sample solution. This procedure results in a three- to fourfold increase in the retention factors of alkylphosphonic acids in comparison with the analogs described in the publications.