A novel microporous copper silicate: Na2Cu2Si4O11.2H2O

The synthesis and structural characterisation of a thermally stable novel three-dimensional microporous copper silicate open-framework are described; the material is capable of undergoing reversible zeolitic water removal without destruction of the framework.     

Pionic x-ray transitions in 3He

Pionic ³He atoms have been produced in a gaseous target. Energies and strong absorption broadening of the 2 → 1 and the 3 → 1 transition lines have been measured. The 1s level is shifted by 44 ± 5 eV by the (attractive) strong interaction, and the natural 1s level width is 42 ± 14 eV.     

Optical Diagnosis for Thyroid and Parathyroid Tissues—A Review

Abstract

This article presents an overview of optical methodologies to aid the diagnosis and differentiation of thyroid and parathyroid tissues. In particular, we review the several techniques and associated methodologies that allow in vivo and ex vivo optical characterization of thyroid and parathyroid tissues. Emphasis is placed on the research potential of these techniques and whether intrinsic characteristics can provide useful contrast for the diagnosis of human thyroid and parathyroid malignant lesions.     

Tunable infrared generation in KTA and applications

Noncollinear difference frequency mixing of dye laser and Nd:YAG second harmonic (fundamental) radiation from a commercial laser system is employed for the generation of 2.7–5.3 μm (1.6–1.7 μm) radiations in a flux-grown KTiOAsO₁ crystal. The generated radiation is used to scan the methane absorption in the fundamental (v ₃) and its first overtone (2v ₃) band at pressure 90 torr in a laboratory made single pass gas cell of length 33 cm.     

Extending the kinetic solution of the classic Michaelis–Menten model of enzyme action

The principal aim of studies of enzyme-mediated reactions has been to provide comparative and quantitative information on enzyme-catalyzed reactions under distinct conditions. The classic Michaelis–Menten model (Biochem Zeit 49:333, 1913) for enzyme kinetic has been widely used to determine important parameters involved in enzyme catalysis, particularly the Michaelis–Menten constant (K _M ) and the maximum velocity of reaction (V _max ). Subsequently, a detailed treatment of the mechanisms of enzyme catalysis was undertaken by Briggs–Haldane (Biochem J 19:338, 1925). These authors proposed the steady-state treatment, since its applicability was constrained to this condition. The present work describes an extending solution of the Michaelis–Menten model without the need for such a steady-state restriction. We provide the first analysis of all of the individual reaction constants calculated analytically. Using this approach, it is possible to accurately predict the results under new experimental conditions and to characterize and optimize industrial processes in the fields of chemical and food engineering, pharmaceuticals and biotechnology.     

Slurry sampling and high-resolution continuum source flame atomic absorption spectrometry using secondary lines for the determination of Ca and Mg in dairy products

The present paper proposes a simple and fast analytical procedure for the sequential multi-element determination of Ca and Mg in dairy products employing sampling slurry and high resolution-continuum source flame atomic absorption spectrometry (HR-CS FAAS). Considering the high concentration of these species in these matrices, the analytical measurements were carried out at the secondary lines of 239.856 and 202.852 for Ca and Mg, respectively. The experimental conditions established for the preparation of the slurries during the optimization step were: 2.0 mol L^{− 1} hydrochloric acid, sonication time of 20 min and sample mass of 1.0 g for a slurry volume of 25 mL. Experiments demonstrated that the analytical curves can be established using the external calibration technique employing aqueous standards. The method allows the determination of Ca and Mg with limits of quantification of 0.038 and 0.016 mg g^{− 1}, respectively. The precision was evaluated under reproducibility and repeatability conditions and expressed as relative standard deviation. The results varied from 2.7 to 2.9% (all tests with n = 10) and using a yogurt sample containing Ca and Mg concentrations of 1.40 and 0.13 mg g^{− 1}, respectively.The accuracy was confirmed by the analysis of a certified reference material of non-fat milk powder furnished by the National Institute of Standard and Technology. The proposed method was applied for the determination of Ca and Mg in yogurt, cow milk and milk powder samples. The samples were also analyzed after complete acid digestion and Ca and Mg determination by HR-CS FAAS. No statistical difference was observed between the results obtained by both of the procedures performed.     

Measurement of thes-wave contribution to 2p-level shifts in pionic atoms

Energies and widths of pionic 3d-2p transitions of₃₀Zn,₃₂Ge, and₃₃As have been measured with a Ge detector. The values of the 2p shifts obtained from the measurementε _2p (Zn)=7.0±1.4keV,ε _2p (Ge)=5.5±0.9keV, andε _2p (As)=4.6±0.9keV show a decreasing behaviour for largeZ, which is caused by an increasings-wave contribution as predicted by theory.