Structural hydroxyl distribution in jadeite grains and the diagenesis mechanism of jadeitite in Myanmar, Guatemala and Russia

Carrying out jadeitite diagenesis in its basic state as well as in combination with the multiple fluid activities of water, we focused on jadeite grains in production areas such as Myanmar, Guatemala and Russia to determinethe essence of nominal anhydrous jadeite grains and the distribution of structural hydroxyl in individual jadeite grains via infrared microscope. This is a scientific problem that urgently needs to be solved. The results show that a microscale of structural water in the form of structural hydroxyl is widely found in the jadeite grains of primary jadeitite in Myanmar, Guatemala and Russia. There are certain differences in the three groups of characteristic infrared absorption bands generated by the stretching vibration of the structural hydroxyl in jadeite from these different producing areas. The structural hydroxyl content of the individual jadeite grain shows obvious differences according to the producing areas, and the structural hydroxyl content in jadeite grains in Myanmar is up to 2522.11 × 10-6. By contrast, jadeite grains in Guatemala and Russia yield lower results. In addition, the structural hydroxyl content in individual jadeite grains in the three producing areas are inhomogeneous, showing an increasing trend from interior to exterior. However, dynamic metamorphism of different intensities and multi-period fluid participation lead to differences in the increase, whereby an increase in structural hydroxyl content in jadeite grains from Guatemala and Russia is slower. The study of the distribution of structural hydroxyl in jadeite grain from different producing areas is helpful for exploring the interaction trajectory of fluids involved in jadeitite and the diagenesis mechanism of jadeitite, a fact that is of great scientific significance for revealing the formation process and conditions of jadeitite.

Распределение катионов Tb-=SUP=-3+-=/SUP=- и Eu-=SUP=-3+-=/SUP=- в решетке C-Gd-=SUB=-2-=/SUB=-O-=SUB=-3-=/SUB=- по данным спектров фотолюминесценции и дальнего ИК

In this work, we investigated the features of the photoluminescence of C-Gd2(1-x)TbxEuxO3 luminophores at x = 1.0 and 2.5 mol%, which are associated with the distribution of Tb3+ and Eu3+ activator ions over the centrosymmetric C3i and noncentrosymmetric C2 positions of cations in the bixbyite lattice, as well as in the positions at the boundaries crystallites CS. We studied the phase transformations of the samples, changes in the morphology of crystallites, photoluminescence spectra, and spectra of the far infrared region 50–600 cm–1 with changes in the annealing modes of the initial products of the sol – gel synthesis Gd2(1 – x)TbxEux(OH)y(CO3)z · n(H2O) at temperatures of 900 and 1200oC in air and hydrogen. Correlations have been established between changes in the characteristics of the samples and the parameters of their annealing. Based on the analysis of these correlations, the redistribution of activators over the indicated cation positions was determined, and a model was proposed for identifying infrared absorption bands in accordance with the localization of activators along the cationic sublattices C3i and C2.

Thieno[1,3,2]oxazaborinine-containing aza-BODIPYs with near infrared absorption bands: synthesis, photophysical properties, and device applications

Structurally constrained NIR aza-BODIPYs with thieno[1,3,2]oxazaborinine were synthesized for the first time, enabling their evaluation as NIR photodetectors through fabrication of a single-component device.

PREPARATION AND FTIR STUDIES OF PMMA/PVC POLYMER BLENDS, PVC-g-PMMA GRAFT COPOLYMERS AND EVALUATING GRAFT CONTENT

This study presents the qualitative and quantitative analyses of Fourier Transform Infrared (FTIR) spectra of poly(methyl methacrylate)/poly(vinyl chloride) blends (PMMA/PVC), as well as PVC-g-PMMA graft copolymers. Graft copolymerizations of methyl mathacrylate (MMA) onto PVC macromolecules were carried out mixture of cyclohexanone/N,N-dimethylformamide as solvents, dibenzoyl peroxide as initiator and nitrogen medium. FTIR spectra of PMMA/PVC blends showed that there were molecular interactions between C=O groups of PMMA and C-Cl groups of PVC. Assignments of infrared absorption bands for specific groups of PMMA/PVC blends have been contributed. Using regression method, linear calibration curve between PMMA mole content and peak areas of C=O groups in FTIR spectra of the blends has been found when C=O peak areas were multiplied by an appropriate factor. PMMA grafted content and total PMMA formed content in PVC-g-PMMA graft copolymers have been evaluated. The results showed that grafted PMMA content was increased since PVC was initiatly dechlorinated by NaOH solution. The grafted PMMA content and total formed PMMA content were 5.05 wt.% and 11.25 wt.% respectively when MMA monomers were grafted onto neat PVC and modified PVC molecules.

Endohedral alkali cations promote charge transfer transitions in complexes of C60 with [10]cycloparaphenylenes

The endohedral alkali cations in M+@C60⋯[10]CPP complexes boost the near infrared absorption bands associated with charge transfer from the nanoring to the fullerene.

EVALUATION OF CALLINECTES CHITOSAN AS A SUPERDISINTEGRANT IN METRONIDAZOLE TABLET

Objective: The objective of this study is to evaluate callinectes chitosan as a superdisintegrant in tablet formulation; superdisintegrants are incorporated into tablets at concentrations below 5% of tablet weight to effect prompt break-up of tablets after administration.Methods: Chitosan was extracted from shells of Callinectes gladiator. The polymer was characterized and then used as a disintegrant (in comparison with Ac-Di-Sol® and corn starch) at concentrations of 2, 4 and 8% for the formulation of metronidazole tablets. The micromeritic properties of granules; and mechanical and release properties of the tablets were studied.Results: A yield of 36.7% chitosan having degree of deacetylation of 62.7% was obtained from the crab shell. Fourier Transform Infrared absorption bands at 1495 and 3240 cm-1 typical of N-H bending and stretching respectively; and endothermic peak of 159 °C typical of melting of chitosan were obtained. No adverse interaction between the chitosan and metronidazole was observed. The disintegration times of tablets containing 2, 4 and 8% chitosan were 12.2, 10.4 and 9.3 min respectively.Conclusion: Callinectes chitosan is suitable for use as a superdisintegrant in tablets. It appears to be superior to corn starch as disintegrant although less effective compared to Ac-Di-Sol®. However, the relative cheapness and ready availability of chitosan would make it to be preferred to Ac-Di-Sol®.