佳木斯台形变观测对东北地区几次浅震“场兆”异常的探讨

大地震在主破裂前往往行成地壳变形,高应力作用下进入峰值后的变形阶段,反映到地倾斜观测日均值曲线上,表现为固体潮形变趋势异常,这些异常能否指示远距离的地震,近年来不少研究者发现,远场前兆往往出现在对应力、应变变化反应灵敏的特殊构造部位。佳木斯台可能处于这种特殊的构造部位,对东北地区浅源地震短期前兆异常“场兆”的趋势性变化具有一定的意义。     

Lead sorption in calcareous soils

The sorption of lead by three soils that differed in texture and calcium carbonate content was studied at three different temperatures. Lead sorption was found to conform to both Freundlich and Langmuir isotherms. Soil adsorption maxima were derived from the reciprocal of the slope obtained by a least-squares fit of Langmuir plots for each soil. The highest adsorption capacity was exhibited by CaCO(3)-rich soil (773.55 mmol Pb kg(-1)). Raising the temperature from 298 K to 308 and 318 K increased the sorption capacity of all of the soils.     

The dangers of skin-lightening creams

Skin-lightening creams are extensively promoted online and in the media. They may contain a wide variety of active ingredients such as mercury, hydroquinone, and steroids that are highly toxic, especially after prolonged application. For more than a decade, we found high mercury content in many products sold on Saudi markets. Some of these products were later banned by the government. However, the presence of other ingredients has not been documented. We undertake this study on some of the most popular skin-lightening creams on the market to test for toxic ingredients such as mercury, titanium dioxide, hydroquinone, and corticosteroids. A total of 33 different brands were selected for the analysis of titanium (50 samples), hydroquinone (55 samples), and corticosteroids (56 samples) with the exception of mercury in which only 23 brands (34 samples) were tested. This study showed that 2 of 34 skin-lightening creams had mercury above the US FDA limit of 1?µg?g^?1. All products had titanium dioxide at less than 25% (w/w) of the EU and US FDA safety limits for personal products but 8 products from 7 different brands contained titanium dioxide above 1%, the permissible limit in cosmetics as color additives. In this study, we found 8 creams from 7 different brands had hydroquinone above 1.5% (w/w), the newly proposed FDA limit of hydroquinone in OTC skin-lightening drug products. Among the four tested corticosteroid compounds, the most frequently detected was cortisone and 18 products from 13 different brands were above 6?µg?g^?1 (MDL) with a maximum of up to 0.32% (w/w). Dexamethasone was found in 7 creams from 5 different brands with only 3 above the MDL of 9?µg?g^?1. Although one might argue that these corticosteroids are of mild or low potency, and they may be unlikely to have any adverse effects, these products are marketed as personal-care products on the assumption that they are safe and free of steroids. The overall results indicate that many of the skin-lightening creams sold in the Saudi market contained one or more toxic ingredients that in most cases were not listed on the packaging. Many of these ingredients are harmful and pose health risks if we take into account the frequency of application, the duration of practice, and area of the body applied, and their use during pregnancy and/or periods of lactation.