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关键词： 化学元素   规范书写   核素   元素符号   分子物理学   物理化学   标注  

摘要： 根据GB3102.8-93《物理化学和分子物理学的量和单位》的规定,现将化学元素和核素符号书写的规范要求介绍如下：（1）元素或核素的单字母符号均用正体大写,双字母符号首字母正体大写,第二个字母用正体小写。（2）核素的核子数（质子数）应标注在元素符号的左上角,例如：^（60）Co、^（32）P、^（99）mTc、^（125）I等;把核子数标注在元素符号右上角的写法是错误的,例如：

关键词： 非化学专业   化学科普实验   头发   微量元素   检测  

摘要： 结合中国科学技术大学的学期改制,在夏季学期面向全校非化学专业的低年级本科生开设了“生活中的化学科普实验”公选课程,课程内容多为与生活密切相关的热点问题.“头发中微量元素的测定”是其实验项目之一.该实验将学生自己的头发作为分析对象,合理地设计教学内容和实验步骤,以期激发学生对化学实验的兴趣,提高学生对化学学科的认识.

关键词： 化学元素   日本   定名   中文名称   化学研究所   应用化学   元素符号   实验设施  

摘要： 2017年3月14日，日本首次发现的113号元素被负责管理化学元素符号的国际化学组织“国际纯粹与应用化学联合会”正式命名为Nihonium，中文名称是“铢”．据报道，113号元素是日本理化学研究所的一个科研小组于13年前在该国崎玉县和光市的实验设施中合成的，是亚洲发现的第一个元素，它的名称来自于“日本”（Nihon）这一国名。

关键词： 高中化学   元素化合物   教学策略  

摘要： 元素化合物是中学化学的重要组成部分,是研究物质及其变化的素材,学生要从原子分子层次理性的认识物质及其变化,要认识化学科学对促进社会可持续发展的价值,没有元素化合物知识的感性认识,是不可能的。因此,对元素化合物的教学应不同于传统的教学方法,面对新课程的要求,教师的教学方法也随着发生相应的改变。学生需要从对原子、分子的认识出发,实现对于元素化合物的物质性质和变化规律的掌握。因此,高中化学元素化合物的教学需要采取系统化的教学策略,按照元素化合物知识的逻辑和线索,有步骤地开展教学。

关键词： 地球化学   铂族元素   辉绿岩   左所   武定   昆阳裂谷  

摘要： 古元古代晚期至中元古代早期,西南康滇地区发生过一次强烈的构造、岩浆及成矿事件,即昆阳裂谷,以广泛出露1.8~1.5 Ga基性岩浆岩及铁铜矿床为重要标志。文章报道了滇中武定地区左所辉绿岩的岩石化学、微量元素、Pb同位素及铂族元素地球化学特征,通过铂族元素地球化学对昆阳裂谷期的岩石圈演化、壳幔相互作用进行了探讨。左所辉绿岩相对富碱(w(Na_2O+K_2O)平均为3.55%),低w(Si O_2),较高的w(Ti O_2)(均值为3.30%)、w(P_2O_5)(平均值0.35%),Ca O/Ti O_2比值(平均值为2.4)及Al_2O_3/Ti O_2比值(平均值为3.4)低,具有典型地幔热柱玄武岩的岩石化学特征。左所辉绿岩微量元素中相对富集大离子半径元素,高场强元素弱亏损,稀土元素中出现弱的Eu负异常,反映了斜长石的轻度结晶分异。辉绿岩具有较高的铂族元素含量,PPGE和IPGE明显分异,PGE原始地幔标准化配分曲线呈较明显的左陡倾型。辉绿岩的Cu/Pd比值均低于原始地幔值,表明原始岩浆S不饱和,亦未发生硫化物的熔离过程,较高的PGE含量可能与初始岩浆本身的S含量较高有关。高的Pd/Ir比值可能与IPGE在部分熔融过程中更倾向于残留相以及岩浆演化早期铬铁矿和橄榄石的结晶分异有关。低程度的地幔部分熔融、Pb同位素特征暗示左所地区辉绿岩的形成过程:陆内裂谷环境下,富硫的原始岩浆在上升过程中受到较少下地壳物质的混染,侵位至浅表并较快冷却,形成辉绿岩。

关键词： Aerobic pretreatment   Fly ash   Combined effect   Methane generation   Mixed sludge  

摘要： The effect of aerobic pretreatment and fly ash addition on the production of methane from mixed sludge is studied. Three assays with pretreated and not pretreated mixed sludge in the presence of fly ash (concentrations of 0, 10, 25, 50, 250 and 500 mg/L) were run at mesophilic condition. It was found that the combined use of aerobic pretreatment and fly ash addition increases methane production up to 70% when the fly ash concentrations were lower than 50 mg/L, while concentrations higher than 250 mg/L cause up to 11% decrease of methane production. For the anaerobic treatment of mixed sludge without pretreatment, the fly ash improved methane generation at all the concentrations studied, with a maximum of 56%. The removal of volatile solids does not show an improvement compared to the separate use of an aerobic pre-treatment and fly ash addition. Therefore, the combined use of the aerobic pre-treatment and fly ash addition improves only the production of methane. (C) 2017 Elsevier Ltd. All rights reserved.

关键词： Xinqiao Cu-S-Fe-Au deposit   Garnet trace element geochemistry   Stratiform mineralization   Middle-Lower Yangtze River Valley   metallogenic belt   Eastern China  

摘要： The Xinqiao Cu-S-Fe-Au deposit in the Tongling ore district, an important part of the Middle-Lower Yangtze River Valley metallogenic belt in eastern China, is located along the northern margin of the Yangtze Block. The deposit consists of two major mineralization types: stratiform and skarn (the genesis of the former is disputed). The more important stratiform orebody (90% of the total Cu, S and Fe reserves) has abundant garnet as the main gangue mineral, similar to the skarn orebody hosted in the intrusive contact. Garnets from the Xinqiao stratiform orebody range from pure andradite (And(100)) to And(50)Gro(46), and can be divided into the early (Grt1) and late (Grt2) generation. Both generations contain low MnO (0.19-0.89%), wide range of Y/Ho (39.0-40.7 for Grtl, 29.8-67.9 for Grt2), and do not contain melt or fluid-melt inclusions, indicative of a magmatic-hydrothermal replacement origin. Grtl and the Grt2 cores are grandite, whilst the Grt2 rims are mainly andradite with some grandite zones. Grandite is enriched in heavy rare earth elements (HREEs), and displays low Sigma LREE/Sigma HREE, La-N/Yb-N and U concentrations with negative Eu anomalies, whereas andradite is HREE-depleted, and displays high Sigma LREE/Sigma HREE, LaN/YbN ratios and U concentrations with positive Eu. anomalies. The distinct trace element features suggest that the hydrothermal fluids for Grt1 and the Grt2 cores were of nearly neutral (pH), relatively oxidized and HREE-enriched, whereas those for the Grt2 rims bad experienced episodic inflections between a mildly acidic, relatively reduced and HREE-depleted fluid and a nearly neutral, relatively oxidized and HREE-enriched fluid. Meanwhile, they also reveal that Grtl and the Grt2 cores may have formed by diffusive metasomatism in a closed system, whereas the Grt2 rims may have formed by infiltration metasomatism in an open fracture system, possibly related to the unconformity that hosts the Xinqiao stratiform ore body. We propose that the

关键词： Platinum-group elements (PGE)   Re-Os isotopes   Lamprophyre   Mantle metasomatism  

摘要： Cenozoic lamprophyres are widespread along the Ailaoshan suture, SW Yunnan, SW China, where there are also many important gold deposits, especially the Zhenyuan deposit. We have carried out a geochemical investigation of the Zhenyuan lamprophyres in terms of major and trace elements, platinum-group elements (PGE), and Os isotopes. The Zhenyuan lamprophyres can be classified into groups with high or low Os concentrations. The Os-187/Os-188 ratios, corrected for in situ growth, are highly variable in both types of lamprophyre, ranging from mantle values up to 1.13. The highly radiogenic Os isotopic signatures are interpreted as being due to long-term accumulation of elevated Re/Os in the lithospheric mantle, as a result of subduction-related metasomatism. The highly variable Os-187-/Os-188 ratios of the low-Os lamprophyres might also have resulted from metasomatism of a deeply derived carbonate melt, which did not elevate Os concentrations significantly. The Zhenyuan lamprophyres feature low PGE contents and can be classified into two groups: A and B, based on their primitive mantle-normalized PGE patterns. Group A is characterized by strongly negative Ru anomalies, while Group B is characterized by slightly negative Ru anomalies and low total PGE contents. The PGE characteristics may be explained by a two-stage model of magma evolution. Very high Cu/Pd and low Pt/Y ratios indicate the first stage involved sulfur saturation and sulfide removal, producing variable total-PGE concentrations, especially in Group B. The second stage involved S-undersaturation and the early crystallization of silicate minerals (e.g., olivine) along with laurite and/or Ru-Ir-Os alloy, fractionating PGEs and producing marked negative Eu anomalies. (C) 2017 Published by Elsevier B.V.

关键词： Trace elements   Experimental petrology   Partition coefficients   REE   HFSE  

摘要： We present new partition coefficients for the REE, HFSE, Sn, In, Ga, Ba, Pt and Rh between clinopyroxene, olivine and basaltic melt as a function of crystal chemistry and melt composition at temperatures of 11901300 degrees C and 1-bar pressure. Two components, namely Al2O3 and Na2O, were chosen to be investigated since they are known to affect the structure of silicate melts and especially clinopyroxene crystal chemistry. The amount of Al-[4]' in clinopyroxene will result in an increase of D-i(cpx/melt) even after applying a correction factor to account for the effect of melt polymerization. Moreover, the positive correlation between Al-[4] and D-i(cpx/melt) is not restricted to the REE, but also applies for Sn, Ga, In, and Ba. The addition of up to 2.6 wt% Na2O to the silicate melt universally increases the D-i(cpx/melt) without any concomitant change in crystal chemistry or a significant effect in melt polymerization. This compositional effect is likely due to the ability of Na to break REE-Al complexes in the melt. Our results emphasize the importance of considering all variables that affect the behavior of trace elements in magmatic systems before applying the lattice strain model and derive meaningful results for the changes in the parameters of the crystallographic sites.

关键词： Dry fermented sausage   Biogenic amines   Polycyclic aromatic hydrocarbons   Minerals   Chemical hazard   Food safety   Food analysis   Food composition  

摘要： This work aims to evaluate the presence of chemical hazards on commercially-available dry fermented sausages (DFS) from different origins and provide preventive recommendations to warrant products safety. Samples (n = 20) were purchased at retail level in different markets of Lisbon (Portugal) and Novi Sad (Serbia). Biogenic amines (BAs), polycyclic aromatic hydrocarbons (PAHs) and heavy elements were determined. Portuguese and Serbian DFS showed low levels of cadaverine (0.6-202 mg/kg and 1.6-291 mg/kg, respectively), putrescine (3.5-401 mg/kg and 1.4-291 mg/kg, respectively) and tyramine (32.6-206 mg/kg and 5.0-246 mg/kg, respectively). Histamine never reached considerable levels in both DFS. Low molecular weight PAHs were the most abundant, comprising more than 90% of total PAHs. Serbian and the majority of Portuguese DFS well meet the EU legislation for the PAHs content. The most prevalent heavy element in DFS from both origins was lead (0.01-0.34 mg/kg). Contents of heavy elements in DFS from Portuguese and Serbian markets indicated that these potential hazards were present but at low risk for consumers. Additional investigation still has to be done regarding selection of autochthonous starters not producers of BAs and smoking step optimization to minimize the contents of BAs and potential toxic PAHs in DFS. (C) 2017 Elsevier Inc. All rights reserved.