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Article in Chinese | WPRIM | ID: wpr-858111


OBJECTIVE: To investigate the effect of adding gold when determing the memory effect and stability of mercury by ICP-MS, and determine the appropriate amount of gold. METHODS: ICP-MS method was used to determine the amount of mercury in the solution. The RF power was 1 550 W, flow rate of carrier gas was 1.05 L•min-1, plasma gas flow rate was 15.0 L•min-1, peristaltic pump speed was 0.2 r•s-1, and sampling depth was 8 mm. The integration time was 0.1 s. RESULTS: Mercury solution began to demonstrate obvious memory effect at the concentration of 0.4 ng•mL-1. It gradually became unstable and the coefficient of variation gradually increased after being placed at room temperature for more than 2 h in the absence of stabilizer. After adding gold, the mercury soulution was stable within 48 h, and the coefficient of variation was within 5%. When the ratio of gold to mercury was 2∶1, the memory effect of mercury was decreaed, and its stability was well guaranteed. There was no difference when the mercury standard solution was prepared with or without other elements. CONCLUSION: This study plays a reference role in the detection and analysis of mercury and provides technical support for the revision and improvement of relevant detection methods.

Article in Chinese | WPRIM | ID: wpr-843587


Objective: To evaluate the efficacy and safety of a long-term adding metformin to a basic treatment strategy in systemic lupus erythematosus (SLE), and analyze whether the beneficial effects of metformin add-on treatment during the open-label proof-of-concept trial persisted during a posttrial follow-up (the metabolic memory effect), as there is a paucity of systematically collected data concerning long-term metformin use in SLE. Methods: Subjects who had participated in the open-label proof-of-concept trial and gave informed consent to this study were enrolled, and the disease flares and long-term adverse effects between metformin group and control group were compared. In addition, whether the benefit regarding decreased disease flare persisted after metformin withdrawal during the post-trial follow-up was investigated. Results: Twenty-nine subjects in the former metformin add-on strategy group and 28 subjects in the former control group were enrolled. No adverse reactions of metformin occurred during the study. The risk of disease flare in the control group was higher than that in the continuous metformin group, but the difference was not statistically significant (P=0.326). After metformin withdrawal, the risk of disease flare in the metformin group gradually increased to the control group (P=0.998). There was no significant difference between the two continuous metformin use groups whose metformin using duration are 2.56 years and 5.00 years respectively (P=0.802). Conclusion: A long-term metformin add-on treatment is security, and can keep SLE patients in a lower risk of disease flare. The metabolic regulation of metformin in SLE immune disorder may present a time-dependent metabolic memory effect.

Rev. dent. press ortodon. ortopedi. facial ; 14(6): 144-157, nov.-dez. 2009. ilus
Article in Portuguese | LILACS, BBO | ID: lil-533073


A grande variedade de fios ortodônticos presente no mercado pode gerar dúvidas quanto à melhor escolha para situações clínicas. Assim, o conhecimento das propriedades mecânicas dos mesmos facilita a escolha para aplicação do movimento ortodôntico na dependência da fase em que o tratamento se encontra. A evolução da tecnologia de manufatura dos fios e a elaboração de novas técnicas ortodônticas geraram a busca por uma melhor qualidade das ligas, a fim de torná-los biologicamente mais efetivos no que diz respeito aos dentes e tecidos de suporte. O presente artigo resume as principais características dos fios utilizados em Ortodontia, em relação ao histórico, propriedades mecânicas e aplicação clínica, de acordo com fases específicas de tratamento.

The huge variety of orthodontic wires brands available in market might generate confusion as regard to the best choice for clinical application. Therefore mechanical properties knowledge about wires would help the professional to apply the best orthodontic technique depending on the treatment phase. The wires manufacturing evolution and the new orthodontic techniques proposed guided the market into the search for better quality alloys, in order to make them biologically more effective to teeth and support tissues. This paper aims to summarize some main characteristics of orthodontic wires related to their history, mechanical properties and clinical application as regard to individual phase of treatment.

Orthodontic Wires/history , Orthodontic Wires , Orthodontics
Rio de Janeiro; s.n; 2007. 120 p. ilus, tab, graf.
Thesis in Portuguese | LILACS, BBO | ID: lil-518362


Objetivou-se nessa pesquisa comparar oito tipos de fios de NiTi superelásticos e termoativos, de seis empresas comerciais (GAC, TP, ORMCO, MASEL, MORELLI e UNITEK) àqueles com adição de cobre (CuNiTi 27 e 35OC, ORMCO), observando se as propriedades mecânicas dos dois últimos justificariam sua escolha clínica. Para tal foram realizados ensaios de tração e microscopia eletrônica de varredura. Os ensaios de tração foram realizados em máquina de ensaios mecânicos da marca EMIC, modelo DL10000, de 10 toneladas de capacidade, no Instituto Militar de Engenharia (IME). A composição química e a topografia superficial dos fios foram determinadas através da microscopia eletrônica de varredura em microscópio da marca JEOL, modelo JSM-5800 LV com sistema de microanálise EDS (energy dispersive spectroscopy). Os resultados mostraram que, de forma geral, os fios de NiTi termoativados apresentaram cargas mais suaves de desativação em relação aos superelásticos. Entre os fios que apresentaram as cargas biologicamente mais adequadas de desativação estão os termoativados da GAC e da UNITEK. Entre os fios de NiTi superelásticos, os de CuNiTi 27ºC da ORMCO foram os que apresentaram as cargas mais suaves de desativação, sendo semelhantes, estatisticamente (ANOVA), às apresentadas pelos fios de NiTi termoativados da UNITEK para a deformação de 4%. Quando comparados os fios de CuNiTi a 27 e a 35ºC, observou-se que os primeiros apresentaram forças de desativação de, aproximadamente, 1/3 das apresentadas pelos últimos, para a deformação de 4%. Quando analisada a microscopia eletrônica de varredura de superfície, os fios de NiTi superelásticos que apresentaram melhores acabamentos foram os da MASEL e MORELLI e os que apresentaram os piores acabamentos foram os de NiTi e CuNiTi 27ºC da ORMCO...

Leveling and aligning orthodontic wires must be able to generate light and continuous forces. Thus need to have high springback and flexibility. For this purpose it was suggested a variety of supereslatic and termoactivated Nickel-Titanium (NiTi) wires that may offer a load-deformation curve, in a constant plataform. Copper NiTi wires are presented as exhibiting better thermoactivating properties for optimum-forces system with better dental movement control. The aim of this study was to compare 8 NiTi superelastic and thermoactivated wires of six different brands (GAC, TP, ORMCO, MASEL, MORELLI and UNITEK) to Copper addicted wires (CuNiTi 270C and 350C, ORMCO) to verify if the mechanical properties of Copper NiTi would support it’s clinical use. Stress-strain tests were done in Engeneering Military Institute (IME-Brazil), through test machine (EMIC- DL 10000 model). Scanning electronic microscope with energy dispersive spectroscopy (JOEL, JSM-5800 LV model) was used to determine chemical composition and superficial topography of the wires. Results showed that, in general, thermoactivated NiTi wires exhibited lower deactivation loads when compared to NiTi superelastics. Among the thermoactivated, the GAC and UNITEK ones are the lighter ones. Among the superelastics, the Copper NiTi 270C (ORMCO) were the lighter ones, statistically similar (ANOVA) to thermoactivated NiTi from UNITEK, for 4% strain. Once Copper NiTi 270C showed deactivated loads 62% lower than Copper NiTi 350C , under 4% strain. As regard to Scanning Electronic Microscopy results for superelastic NiTi wires, better superficial burnishing were found for MASEL and MORELLI ones...

Copper , Nickel , Orthodontic Wires , Orthodontics/methods , Titanium , Analysis of Variance , Calorimetry , Elasticity , Microscopy, Electron, Scanning , Tensile Strength
Article in English | WPRIM | ID: wpr-643532


The great variety of commercial brands of orthodontic wires available on the market, stimulated by the so called superior wires (nickel titanium with shape memory effect and superelastic nickel titanium), makes the professional choice for a suitable and less expensive material difficult. The in vitro study of the mechanical properties of the orthodontic wires acts as an auxiliary tool for the professional. In this paper, a comparative study of mechanical properties was made, using stress strain tests for 4 types of orthodontic wires (conventional stainless steel, multistranded steel, superelastic nickel titanium and thermoactivated nickel titanium) separated into 5 groups. A series of 6 tests were tested for each group of wires. Initially, each group was tested 3 times until the wires broke. Furthermore, 3 more tests for each group were performed, stretching the wires under standardized activation loads, for a reliable comparison of their mechanical properties, during loading and unloading. t tests were applied to check differences among the groups. In vitro, the results suggest that regarding the mechanical properties supposedly desirable for physiological teeth movement, such as resilience, elasticity modulus, strength liberated during unloading, and the way that strength is liberated, thermoactivated nickel titanium wires, acting under mouth temperature, seems to be a good choice, followed by superelastic nickel titanium, multistranded stainless steel, and conventional stainless steel. Superelasticity was demonstrated for superelastic nickel titanium wires. When at 37degrees C, thermoactivated nickel titanium wires showed shape memory effect, showing that temperature is important for enhancing the mechanical properties.

Alloys , Elastic Modulus , Memory , Mouth , Nickel , Orthodontic Wires , Stainless Steel , Steel , Titanium , Tooth