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181.
David Donnermeyer Magdalena Ibing Sebastian Bürklein Iris Weber Maximilian P. Reitze Edgar Schfer 《Materials》2021,14(4)
The aim of this study was to gain information about the effect of thermal treatment of calcium silicate-based sealers. BioRoot RCS (BR), Total Fill BC Sealer (TFBC), and Total Fill BC Sealer HiFlow (TFHF) were exposed to thermal treatment at 37 °C, 47 °C, 57 °C, 67 °C, 77 °C, 87 °C and 97 °C for 30 s. Heat treatment at 97 °C was performed for 60 and 180 s to simulate inappropriate application of warm obturation techniques. Thereafter, specimens were cooled to 37 °C and physical properties (setting time/flow/film thickness according to ISO 6876) were evaluated. Chemical properties (Fourier-transform infrared spectroscopy) were assessed after incubation of the specimens in an incubator at 37 °C and 100% humidity for 8 weeks. Statistical analysis of physical properties was performed using the Kruskal-Wallis-Test (P = 0.05). The setting time, flow, and film thickness of TFBC and TFHF were not relevantly influenced by thermal treatment. Setting time of BR decreased slightly when temperature of heat application increased from 37 °C to 77 °C (P < 0.05). Further heat treatment of BR above 77 °C led to an immediate setting. FT-IR spectroscopy did not reveal any chemical changes for either sealers. Thermal treatment did not lead to any substantial chemical changes at all temperature levels, while physical properties of BR were compromised by heating. TFBC and TFHF can be considered suitable for warm obturation techniques. 相似文献
182.
生活垃圾焚烧飞灰基本特性及稳定化研究 总被引:2,自引:0,他引:2
对飞灰的化学组分和矿物结构、重金属含量及浸出毒性、二恶英类有机物的含量以及稳定化后产物的浸出毒性进行了试验研究,结果表明:焚烧飞灰属于SiO2-Al2O3-Fe2O3金属氧化物体系,具有一定的胶凝活性,重金属Pb、Cd、Zn的浸出浓度超过GB 5085.3—2007危险废物鉴别标准浸出毒性鉴别要求,二恶英毒性当量为553.6 ng/kg,经添加水泥和螯合剂稳定化处理后,重金属浸出毒性满足GB 16889—2008生活垃圾填埋场污染控制标准的入场要求,可直接送填埋场处置,为以后飞灰稳定化研究和应用提供参考。 相似文献
183.
Yuting Du ;Jie Zhang ;Qian Zheng ;Mingxin Li ;Yang Liu ;Baoping Zhang ;Bin Liu ;Hong Zhang ;Guoying Miao 《中国神经再生研究》2014,9(11):1129-1137
Heavy ion beams with high linear energy transfer exhibit more beneifcial physical and biological performance than conventional X-rays, thus improving the potential of this type of radiotherapy in the treatment of cancer. However, these two radiotherapy modalities both cause inevitable brain injury. The objective of this study was to evaluate the effects of heavy ion and X-ray irra-diation on the cytoskeleton and cytomechanical properties of rat cortical neurons, as well as to determine the potential mechanism of neuronal injury after irradiation. Cortical neurons from 30 new-born mice were irradiated with heavy ion beams at a single dose of 2 Gy and X-rays at a single dose of 4 Gy;subsequent evaluation of their effects were carried out at 24 hours after irradiation. An immunolfuorescence assay showed that after irradiation with both the heavy ion beam and X-rays, the number of primary neurons was signiifcantly decreased, and there was ev-idence of apoptosis. Radiation-induced neuronal injury was more apparent after X-irradiation. Under atomic force microscopy, the neuronal membrane appeared rough and neuronal rigidity had increased. These cell changes were more apparent following exposure to X-rays. Our ifnd-ings indicated that damage caused by heavy ion and X-ray irradiation resulted in the structural distortion and rearrangement of the cytoskeleton, and affected the cytomechanical properties of the cortical neurons. Moreover, this radiation injury to normal neurons was much severer after irradiation with X-rays than after heavy ion beam irradiation. 相似文献
184.
Michael T. McKay Grant B. Morgan Kevin E. Wells Frank C. Worrell Jon C. Cole James R. Andretta 《Addiction Research & Theory》2019,27(3):189-197
Time Perspective researchers are concerned with the way in which a combination of thoughts and feelings about the past, present and future influence behaviour. Time attitudes comprise a dimension of time perspective where the focus is narrowed to evaluative feelings about the three time periods. The present study included four waves of data gathered in the United Kingdom, and focused on time attitudes. Participants were adolescents in High schools who completed both the Adolescent and Adult Time Inventory-Time Attitudes Scale, at waves one to three (corresponding to High school years 1 to 3), and surveys of heavy episodic drinking (HED) and drunkenness at wave four (year 4 of High school). Four time attitudes profiles were identified (Positives, Negatives, Negative Futures, and Ambivalents), and the majority of adolescents (75.2%) transitioned between profiles at least once during the three waves of data collection. Fully adjusted analyses tentatively supported the relationship between having a positive time attitudes profile and reduced levels of HED, frequency of lifetime drunkenness, and age of first of drunkenness, with small to moderate effect sizes. Results suggested that the development and maintenance of a positive time attitudes profile might be protective against problematic drinking behaviour in adolescence. Consistent with related studies, it is clear that some time attitudes profiles are associated with less risky and healthier alcohol use behaviours than others, which has implications for possible intervention for problematic drinkers. 相似文献
185.
Sara Raponi Caterina Ilari Irene Della Starza Luca V. Cappelli Luciana Cafforio Alfonso Piciocchi Valentina Arena Paola Mariglia Francesca R. Mauro Massimo Gentile Giovanna Cutrona Riccardo Moia Chiara Favini Fortunato Morabito Davide Rossi Gianluca Gaidano Anna Guarini Ilaria Del Giudice Robin Foà 《British journal of haematology》2020,189(5):853-859
In chronic lymphocytic leukaemia (CLL), caution is warranted regarding the clinical implications of immunoglobulin variable heavy chain region (IGHV) rearrangements with a ‘borderline’ (BL) percentage of mutations (i.e. 97–97·9% IGHV identity). We analysed the IGHV mutational status in 759 untreated CLL patients (cohort 1). BL-CLL (n = 36, 5%) showed a time to first treatment (TFT) similar to that of M-CLL (n = 338) and significantly longer than that of UM-CLL (n = 385), despite the enrichment in subset #2 cases. In fact, CLLs belonging to subset #2 (n = 15/759, 2%) were significantly more frequent among BL-CLLs (n = 5/36, 14%), with a brief TFT. TFT of BL-CLL remained comparable to that of M-CLL also considering the 327 CLL patients evaluated at diagnosis. These findings were then validated in an independent cohort 2 of 759 newly diagnosed CLL patients (BL-CLL: n = 11, 1·4%) and in all newly diagnosed patients from cohorts 1 and 2 (n = 1 086, 84% stage A; BL-CLL: n = 47, 4·3%). BL-CLL at diagnosis showed a biological profile comparable to that of M-CLL with a low frequency of unfavourable prognostic markers, except for a significant enrichment in subset #2. Our data suggest that the prognosis of BL-CLL is good and similar to that of M-CLL, with the exception of subset #2 cases. 相似文献
186.
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188.
This paper examines the short- and medium-term effects of the PensionDanmark Health Scheme, the largest privately administered health program for workers in Denmark, which provides prevention and early management of work-related injuries. We use a difference-in-differences approach that exploits a natural variation in the program rollout across collective agreement areas in the construction sector and over time. The results show only little evidence of an effect on the prevention of injuries requiring medical attention in the first 3 years after the program was introduced. Despite this, we find evidence of significant positive effects on several labor market outcomes, suggesting that the program enables some work-injured individuals to maintain their work and earnings capacity. In view of its low costs, the program appears to be cost-effective overall. 相似文献
189.
Juhua Luo Michael Hendryx 《International journal of environmental health research》2014,24(2):125-136
Experimental studies have shown that both cadmium (Cd) and lead have potent endocrine disrupting activity. However, studies on whether these heavy metals disrupt thyroid system in humans, especially in general populations with low levels of exposure, are sparse. The study analyzed 6,231 participants aged 20 and older with measurements from 2007–2010 of the National Health and Nutrition Examination Survey (NHANES) to investigate whether whole blood Cd and lead level are associated with serum thyroid hormones measures. Our study suggests that thyroid function may be disrupted by both Cd and lead exposures in the general population and the specific roles of Cd and lead exposure on thyroid axis may differ by sex. However, the mechanisms by which these heavy metals may disrupt thyroid system function in general population needs to be further investigated. 相似文献
190.