KF／Al2O3催化下导眠能的合成

采用ＫＦ／Ａｌ２Ｏ３催化合成镇静药导眠能,具有反应条件温和,操作简便,产率高的特点。     

Estimation of Potential Health Effects from Acute Exposure to Hydrogen Fluoride Using a "Benchmark Dose" Approach

Communities across the United States are examining the manufacture, use, transport, and storage of hydrogen fluoride (HF) near residential areas as a consequence of a major release of HF in Texas in 1987. Reference exposure levels for routine and accidental HF emissions are calculated using existing animal and human data. The approach employs a logprobit extrapolation of concentration-response data to the 95% lower confidence limit on the toxic concentration producing a "benchmark dose" of 1% response (TC01), called a practical threshold. Species-specific and chemical-specific adjustment factors are applied to develop exposure levels applicable to the general public. Using this method, the 1-hr reference exposure level to protect the public against any irritation from a routine emission (REL-1) is 0.7 ppm and the level to protect against severe irritation from a once-in-a-lifetime (REL-2) release is 2 ppm. This approach is compared to a modified "uncertainty factor" approach.     

氧化镝、氟化钠分解电压的测定及其热力学分析

用线性扫描伏安法测得氧化镝和氟化钠的分解电压(以玻璃化碳为研究电极)分别是 E~(900℃)=1.34V 和 E~(970℃)=2.71V。热力学分析表明实测分解电压与理论分解电压相差较大的主要原因是阳极上的去极化作用——阳极上形成四氟化碳(对 NaF)或一氧化碳(对Dy_2O_3)。     

温度对聚合物QCM传感器性能的影响研究

以聚偏氟乙烯(PVDF)为敏感材料,石英晶体微天平(QCM)为敏感元件构成聚合物QCM传感器。该文主要对神经毒剂模拟剂DMMP的气敏特性进行研究,并重点讨论了温度对PVDF聚合物膜层QCM传感器性能的影响。结果表明,当测试温度愈接近PVDF的玻璃化温度,传感器的响应幅值就愈高,且在各个DMMP测试气氛浓度时,传感器的响应幅值对温度的依赖性均符合Arrhenius关系;升高温度有利于提高传感器的响应速度,但同时其灵敏度却降低。     

氟化钕的制备条件及组成研究

探讨了以碳酸氢铵转型制备氟化钕工艺中的有关影响因素。用Ｘ射线衍射分析、Ｘ射线荧光光谱分析、电镜及热分析等方法对产物进行了表征。研究结果表明在选定的条件下，氟化钕沉淀速度快，容易过滤洗涤，稀土收率高，产品纯净     

蚕业生产中抗氟性育种可能性的探讨

实验对15个蚕品种进行了抗氟性测定，发现在不同的蚕品种之间，存在着大约35倍的抗氟性差异。对4个不同保育地的杭7、杭8蚕原种进行抗氟性测定，发现在不同保育地的同一品种之间存在着3～4倍的抗氟性差异，试验结果表明，现有蚕品种资源中，存在能够抵抗现有氟污染的抗源，自然选择能够提高蚕的抗氟性水平。     

稀土掺杂复合氟化物纳米晶的制备和发光特性

综述了纳米发光材料的发展现状,着重阐述了稀土掺杂复合氟化物纳米晶的制备和荧光性质,并对这一新兴领域进一步的研究工作作了展望.     

Suppression by medical journals of a warning about overdosing formula‐fed infants with fluoride

In January 1990, a short letter was sent to the editor of the international medical journal, Pediatrics, to alert its readers that the standard, highly quoted paper by Singer and Ophaug on fluoride intake by infants, published in 1979 in the same journal, required revision/correction in order to protect one group of infants from receiving substantial overdoses of fluoride. This group comprises infants who are fed almost entirely on powdered formula which is reconstituted with fluoridated water.

The letter was based on the well‐established pediatric guidelines of water intake by infants and the fundamental toxicological principle of protecting groups at highest risk. It did not question the fluoridation of public water supplies. Nevertheless, the letter, together with a response to it by Ophaug, was rejected by the editor of Pediatrics, “due to a large backlog of articles.”; Following a protest, the letter was reviewed by three referees, two of whom conceded its main point, but was still not published.

In the present paper, the original, previously unpublished letter on fluoride intake by infants is first reproduced verbatim, and then the comments of the referees and editors are reported and examined. It is concluded that the most plausible explanation for the rejection of the letter is that it might assist the anti‐fluoridation movement. Another possible contributing explanation is that publication of the letter might reduce the status of the scholars who had defended the previous position and might be perceived to diminish the status of the journal.     

A Case Study Comparing Static and Spatially Explicit Ecological Exposure Analysis Methods

Exposure to chemical contaminants must be estimated when performing ecological risk assessments. A previous article proposed a habitat area and quality conditioned population exposure estimator, E[HQ]P, and described an individual-based, random walk, Monte Carlo model (SE3M) to facilitate calculation of E[HQ]P. In this article, E[HQ]P was compared with exposure estimates from a baseline risk assessment that evaluated mink and great blue heron exposure to fluoride at a federal Superfund site. Calculation of E[HQ]P took into consideration a receptor's forage area, movement behavior, population size, and the areal extent and quality of suitable habitat. The baseline assessment used four methods that did (total and unit Tier 2) and did not (total and unit Tier 1) consider habitat area or quality; where "total" included all exposure units on site and "unit" only a given exposure unit. Total Tier 1 estimates were consistently higher than E[HQ]P (e.g., 169.1 mg/kg x d versus 21.6 mg/kg x d). Risk managers using total Tier 1 results for decision making would be unlikely to underestimate exposure; however, implementability of correspondingly lower remedial objectives could be challenging. Unit Tier 1 estimates were higher (e.g., 96.5 mg/kg x d versus 61.6 mg/kg x d) or lower (e.g., 3.5 mg/kg x d versus 51.1 mg/kg x d) than E[HQ]P depending on variations in landscape features. Total Tier 2 and E[HQ]P estimates were similar (e.g., 20.7 mg/kg x d versus 21.6 mg/kg x d) when an ecologically questionable average exposure was assumed. Unit Tier 2 estimates were consistently well below E[HQ]P (e.g., 17.8 mg/kg x d versus 61.6 mg/kg x d) when an average exposure was not assumed. Risk managers using unit Tier 1 or 2 results could be basing their decisions on potentially large underestimates of exposure. By forgoing average exposure assumptions, and explicitly addressing landscape heterogeneity, SE3M appears capable of yielding exposure estimates that are not as potentially misleading to risk managers as those produced with traditional averaging methods.     

碱式氯化铝中三氧化二铝含量的测定——氟电极直接电位法

在微酸性溶液中,加入一定过量的氟化钾沉淀剂,使铝与它定量生成铝氟酸钾沉淀.用氟离子选择电极测定过量的 F~-量,间接计算出试样中铝的含量。此法简便、快速、干扰少、结果与常规的络合滴定法相比无显著性差异.