[Study on quality status of mineral medicine Calamina].

In this paper, some quality problems of mineral medicine Calamina and calcined Calamina have been discussed after determination and analysis of the quality parameters of a large number of market samples, and the countermeasures are put forward. According to the XRD results, as well as the results of tests included in Chinese Pharmacopoeia(2015 edition), the authenticity of Calamina and calcined Calamina samples were identified. The content of zinc oxide in samples were determined by the method of determination in Chinese Pharmacopoeia. Individually, inductively coupled plasma mass spectrometry(ICP-MS), inductively coupled plasma atomic emission spectrometry(ICP-AES) and atomic fluorescence spectrometry(AFS) methods were used for the determination of impurity elements and harmful elements in Calamina and calcined Calamina samples. Four kinds of impurity elements of magnesium(Mg), iron(Fe), aluminum(Al), calcium(Ca) and five harmful elements such as lead(Pb), cadmium(Cd), arsenic(As), copper(Cu), mercury(Hg) were measured. The study showed that: ① Fake Calamina products on the market were overflowing; ② The mineral origin of the mainstream Calamina in the market is inconsistent with that stipulated in Chinese Pharmacopoeia(2015 edition); ③ The contents of harmful elements Pb and Cd in Calamina and calcined Calamina are generally higher, while the contents of harmful elements As and Cu in some inferior Calaminae are higher; ④ Parts of calcined Calamina were improperly or inadequately processed. In view of these quality problems, the countermeasures are put forward as follows: ① It is suggested that hydrozincite should be approved as the mineral source of Calamina, and be included by Chinese Pharmacopoeia; ② Strengthen the research on the specificity of Calamina identification methods to improve the quality control level; ③ Strengthen the research on the processing of Calamina, and formulate the limit standards for the content of Pb and Cd in Calamina; ④ Carry out research on the artificial synthesis of Calamina and calcined Calamina, in order to cope with the current shortage of Calamina resources and ensure the sustainable development of Calamina medicinal materials.

Study on quality status of mineral medicine Calamina / 中国中药杂志

In this paper, some quality problems of mineral medicine Calamina and calcined Calamina have been discussed after determination and analysis of the quality parameters of a large number of market samples, and the countermeasures are put forward. According to the XRD results, as well as the results of tests included in Chinese Pharmacopoeia(2015 edition), the authenticity of Calamina and calcined Calamina samples were identified. The content of zinc oxide in samples were determined by the method of determination in Chinese Pharmacopoeia. Individually, inductively coupled plasma mass spectrometry(ICP-MS), inductively coupled plasma atomic emission spectrometry(ICP-AES) and atomic fluorescence spectrometry(AFS) methods were used for the determination of impurity elements and harmful elements in Calamina and calcined Calamina samples. Four kinds of impurity elements of magnesium(Mg), iron(Fe), aluminum(Al), calcium(Ca) and five harmful elements such as lead(Pb), cadmium(Cd), arsenic(As), copper(Cu), mercury(Hg) were measured. The study showed that: ① Fake Calamina products on the market were overflowing; ② The mineral origin of the mainstream Calamina in the market is inconsistent with that stipulated in Chinese Pharmacopoeia(2015 edition); ③ The contents of harmful elements Pb and Cd in Calamina and calcined Calamina are generally higher, while the contents of harmful elements As and Cu in some inferior Calaminae are higher; ④ Parts of calcined Calamina were improperly or inadequately processed. In view of these quality problems, the countermeasures are put forward as follows: ① It is suggested that hydrozincite should be approved as the mineral source of Calamina, and be included by Chinese Pharmacopoeia; ② Strengthen the research on the specificity of Calamina identification methods to improve the quality control level; ③ Strengthen the research on the processing of Calamina, and formulate the limit standards for the content of Pb and Cd in Calamina; ④ Carry out research on the artificial synthesis of Calamina and calcined Calamina, in order to cope with the current shortage of Calamina resources and ensure the sustainable development of Calamina medicinal materials.

Optimization of Bi2O3, TiO2, and Sb2O3 doped ZnO-based low-voltage varistor ceramic to maximize nonlinear electrical properties.

In ZnO-based low voltage varistor, the two essential features of microstructure determining its nonlinear response are the formation Bi-enriched active grain boundaries as well as a controlled ZnO grain size by secondary spinel-type phases. Besides, the microstructure and phase composition are strongly affected by the dopant concentration during sintering process. In this study, the optimal dopant levels of Bi2O3, TiO2, and Sb2O3 to achieve maximized nonlinear electrical property (alpha) were quantified by the response surface methodology (RSM). RSM was also used to understand the significance and interaction of the factors affecting the response. Variables were determined as the molar ratio of Bi2O3, TiO2, and Sb2O3. The alpha was chosen as response in the study. The 5-level-3-factor central composite design, with 20 runs, was used to conduct the experiments by ball milling method. A quadratic model was established as a functional relationship between three independent variables and alpha. According to the results, the optimum values of Bi2O3, TiO2, and Sb2O3 were obtained 0.52, 0.50, and 0.30, respectively. Under optimal conditions the predicted alpha (9.47) was calculated using optimal coded values from the model and the theoretical value is in good agreement with the value (9.43) obtained by confirmation experiment.

Standard addition method applied to solid-state stripping voltammetry: determination of zirconium in minerals and ceramic materials.

An application of the standard addition method to stripping voltammetry of solid materials immobilized in inert electrodes is described. The method allows the determination of the mass fraction of a depositable metal M in a material on addition of known amounts of a standard material containing M to a mixture of that material and a reference compound of a second depositable metal, R. After a reductive deposition step, voltammograms recorded for those modified electrodes immersed in a suitable electrolyte produce stripping peaks for the oxidation of the deposits of M and R. If no intermetallic effects appear the quotients between the peak areas and the peak currents for the stripping oxidation of M and R vary linearly with the mass ratio of the added standard and the reference compound, thus providing an electrochemical method for determining the amount of M in the sample. The method has been applied to the determination of Zr in minerals, ceramic frits, and pigments, using ZnO as reference material and ZrO(2) as the standard.

Avaliação das propriedades físico-químicas de cimentos obturadores de canais radiculares / Property evaluation of different endodontic sealers: a comparative study

Tendo como base a norma ISO/DIS 6876.2, reedição da norma da ADA n° 57 foram avaliadas diferentes propriedades físico-químicas de cinco cimentos obturadores de canais radiculares comumente empregados na clínica diária: Óxido de Zinco e Eugenol, Endométhasone Endofill, AH Plus e Sealer 26. Os cimentos analisados apresentaram valores de escoamento, tempo de trabalho, tempo de presa, solubilidade e radiopacidade que satisfazem a norma ISO/DIS 6876.2

Zinc oxide eugenol cements. VI. Effect of zinc oxide type on the setting reactions.

The particle size and adsorbed water on zinc oxide from various sources have been investigated and related to the reactivity with eugenol. The reactivity of zinc oxide with eugenol alone increases with the amount of water reversibly adsorbed. When 1% acetic acid is added to eugenol, the reactivity increases as the particle size of the oxide decreases. Generally, zinc oxide powders are deactivated by heat treatment because of coalescence of particles and loss of the ability to readsorb water.

[Biological testing of pulp-preserving agents on the pulp of rat molars]. / Biologische Prüfung von Pulpaschutzmitteln an der Molarenpulpa der Ratte.

The effects of calxyl, ZOE, zinc oxide without eugenol, and zinc oxide with an antibacterial substance (glutaraldehyde) were tested on perforated molar pulps of rats. All of the substances tested were found to lead to the same initial reactions (acute inflammation and partial necrosis). Calxyl and ZOE yielded unfavorable results. There was a negligible tendency of the pulp toward hard tissue demarcation. Zinc oxide without eugenol improved the formation by the pulp of secondary tin. - The use of glutaraldehyde resulted in a less pronounced spread of inflammation as well as in the formation of new hard tissue in one half of the cases. Molars of rats are particularly suitable for biologically examining the local toxicity of pulpal protectives and the regeneration of the pulp. The results presented in this paper are discussed from the point of view of pulp-preserving therapy and of avoiding invasion by germs.