Evidence of fluid evolution of Baoshan Cu−Pb−Zn polymetallic deposit: Constraints from in-situ sulfur isotope and trace element compositions of pyrite

In-situ LA-ICP-MS and S isotopes of pyrite from the Baoshan Cu polymetallic deposit were conducted to investigate the ore-forming process and the enrichment mechanism of elements. Three generations of pyrite (Py I, Py II, and Py III) in the skarn-type ores and pyrite in the carbonate-hosted sulfide ores from central, western, and northern (C_Py, W_Py, and N_Py) mining districts are selected for comparison. Compared with Py I and Py III, the contents of most elements in Py II are apparently higher. The As and Se contents are high within a wide range and are decoupled in the growth band of the C_Py. The highest As, Se, and Pb contents were found in W_Py and N_Py. These results indicate the drastic changes in the temperature and fluid mixing during the mineralization. The occurrence of fluctuation and change in temperature and f(O₂) was triggered by intermittent pulses of magmatic-hydrothermal fluids, mixing with meteoric water, and water−rock interactions. The sulfur isotopes of all species of pyrite indicated the magmatic source. The change in the f(O₂) conditions caused slight differences in the sulfur isotope compositions. Consequently, a metallogenic model was proposed to explain the ore-forming processes.     

催化共振光散射法测定空气中痕量甲醛的研究

吖啶橙分子聚集体微粒可在513nm波长处出现最大的共振光散射强度(RLS)。在稀硫酸介质中,甲醛能催化溴酸钾氧化吖啶橙的反应,促使其RLS强度减弱。在最佳实验条件下,甲醛质量浓度ρ在0.020～0.25μg/mL的范围内与△I值呈良好的线性关系,线性回归方程为△I=1113.99ρ+49.23,线性相关系数r为0.9986。本法与国标法进行对照,在置信度等于95%时,用Cochran检验,两种方法间不存在显著性差异,方法操作简单、灵敏度高,用于室内外空气中甲醛测定,结果满意。     

基于三维纳米阵列结构的表面增强拉曼技术研究及其在痕量铀酰离子探测中的应用

表面增强拉曼散射(SERS)是一种新型痕量表征技术，其灵敏度高、样品用量少、特征谱易辨识，尤其适用于铀酰离子等危化品的探测。在过去十几年里, 纳米材料和纳米技术在新兴技术和SERS的应用方面获得了长足发展，将先进的纳米制造技术引入了SERS领域。本文总结了利用光刻、原子层沉积等技术，开发了一系列高质量的三维阵列纳米材料作为SERS基底，并应用于痕量铀酰离子的检测。其中，以Al₂O₃、HfO₂等惰性氧化物包裹修饰的银纳米棒三维阵列作为基底，灵敏度高，稳定性好，根据不同特征的拉曼振动频谱，可识别多个不同种态的铀酰离子，检出限低至nmol/L，具有潜在的实际应用价值。     

针对多种处理痕迹的数字语音取证算法

现有的数字语音取证研究主要集中于对单一的某种操作进行检测，无法对不相关的操作进行判断。针对该问题，提出了一种能够同时检测经过变调、低通滤波、高通滤波和加噪这四种操作的数字语音取证方法。首先，计算语音的归一化梅尔频率倒谱系数（MFCC）统计矩特征；然后通过多个二分类器对特征进行训练，并组合投票得到多分类器；最后使用该多分类器对待测语音进行分类。在TIMIT以及UME语音库上的实验结果表明，归一化MFCC统计矩特征在库内实验中均达到了97%以上的检测率，且在对MP3压缩鲁棒性测试的实验中，检测率仍能保持在96%以上。     

不同产地菜籽油中微量元素的ICP-MS/MS法测定及统计比较

研究菜籽油中微量元素含量的分布规律及其与菜籽油产地之间的关系。采用电感耦合等离子体串联质谱(ICP-MS/MS)法测定了15种菜籽油中Be、Ti、Cr、Mn、Fe、Co、Ni、Cu、Zn、As、Se、Sr、Cd、Ba、Hg、Pb 16种微量元素的含量,将测定数据进行标准化处理后利用SPSS主成分分析与聚类分析对微量元素的分布进行评价。结果表明:菜籽油经煤油稀释后直接进样分析,在MS/MS模式下,分别选择O_2和NH_3/He为反应气,利用CRC技术消除了质谱干扰; Fe、Mn、Cu、Zn、Sr、Ba在0～500μg/kg范围内相关系数大于等于0. 999 8,其余10种分析元素在0～50. 0μg/kg范围内相关系数大于等于0. 999 6,16种元素的检出限为1. 05～20. 30 ng/kg;主成分分析结果显示累积方差的84. 487%来自前6个主成分,菜籽油的特征元素为Mn、Fe、Cu、Sr,聚类分析将15种菜籽油聚为3类,实现了不同产地菜籽油的初步判别。通过微量元素的主成分分析与聚类分析,可对菜籽油进行有效的产地溯源。     

黔西南某中高硫煤脱硫过程中微量元素的分配特性研究

为探究黔西南某中高硫煤中微量元素的富集程度,以及在脱硫降灰提质利用过程中微量元素的分配特性,通过摇床对其脱硫降灰进行了试验研究,并在合适的分选工艺条件下,考察了原煤、精煤和尾煤产品中微量元素的分配特征。通过“一粗一精一扫”重选,可获得产率32.83%、硫分0.96%、灰分11.16%的合格精煤产品。分选产品微量元素分析结果表明,该分选工艺对Cu、Sb、As、Co、Mo、TI、Ni等有害元素具有较好的脱除效果,并能一定程度富集锂和稀土等有价微量元素。通过此工艺可分别回收28.73%和47.37%的锂至精煤和中煤产品,精煤煤灰中Li₂O理论含量达5 258 μg/g,具有综合回收利用价值。研究结果可为该类中高硫煤炭资源的清洁与综合利用提供参考。     

Evaluation of microbial toxins,trace elements and sensory properties of a high-theabrownins instant Pu-erh tea produced using Aspergillus tubingensis via submerged fermentation

Theabrownins (TB) are polymeric phenolic compounds associated with the multiple bioactivities of Pu-erh tea, a post-fermented Chinese dark tea. High-TB instant Pu-erh tea was produced via a novel submerged fermentation (SF) using Aspergillus tubingensis and compared with samples produced commercially via the conventional solid-state fermentation (SSF). Viable microorganisms and microbial toxins, especially aflatoxins B₁, G₁, B₂, G₂, cyclopiazonic acid, fumonisins B₁, B₂, B₃ and ochratoxin A, were below the detection limit in all samples. Fewer microbial metabolites were found in SF instant tea compared with the SSF teas. Based on an adult consuming 1 g of instant Pu-erh tea daily, the dietary intake of investigated elements was below the safe limits recommended by various authorities. Tasters viewed the instant tea infusions as very mild, smooth, mellow and full. This suggested that submerged fermentation using A. tubingensis offers a speedy and safe alternative to commercial production of instant Pu-erh tea.     

基于ICP-MS的不同品种柑橘中矿物元素的差异性分析

研究春见蜜柑、不知火、茂谷柑三种不同种属不同产地柑橘中Na、K、Mg、Mn、Ca、Fe、Zn、Cu八种矿质元素的含量,从四个省份9个产地收集三个品种27个样品。采用微波消解-电感耦合等离子体质谱法检测样品中的8种矿质元素。同时采用主成分分析法和聚类分析法对不同品种不同产地间矿质元素含量的差异进行分析,检测结果表明三个柑橘品种样品中常量元素钾的含量最高,均在1000 mg/kg以上,占8种元素总含量的60%以上,其次为钙、镁,钠,钠为常量元素中含量最低的元素;主成分分析结果表明,前两个主成分方差贡献率为72.4%,K、Mg、Zn、Cu、Mn、Fe是不同品种及产地来源柑橘的特征差异元素;聚类分析结果表明同品种内不同产地样品矿物元素含量有差异,品种造成的元素含量差异明显大于由产地环境引起的差异。     

Experimental study on mercury content in flue gas of coal-fired units based on laser-induced breakdown spectroscopy

Accurate measurement of trace heavy metal mercury(Hg) in flue gas of coal-fired units is great significance for ecological and environmental protection.Mixed gas was used to simulate the actual flue gas of a power plant in this study.A laser-induced breakdown spectroscopy(LIBS)system for Hg measurement in mixed gas was built to study the effect of mixed gas pressure,Hg concentration in mixed gas and delay time on Hg measurement.The experimental results show that the appropriate low mixed gas pressure can obtain high Hg signal intensity and signal to noise ratio.The Hg signal intensity and signal to noise ratio increased with the increase of Hg concentration in mixed gas.The Hg signal intensity and signal to noise ratio decreased with the increase in delay time.According to the above results,the optimized measurement conditions can be determined.Different Hg concentrations in mixed gas were quantitatively analyzed by the internal standard method and traditional calibration method respectively.The relative error of prediction of the test sample obtained by the internal standard method was within 11.11%.The relative error of prediction of the traditional calibration method was less than 14.54%.This proved that the internal standard method can improve the accuracy of quantitative analysis of Hg concentration in flue gas using LIBS.