超声辅助酶法提取-原子荧光光谱法测定富硒黑木耳中硒形态

建立了富硒黑木耳中硒代胱氨酸、硒代半胱氨酸、亚硒酸、硒蛋氨酸、硒酸5种硒形态的液相色谱-原子荧光光谱分析方法。通过链酶蛋白酶E酶解,结合超声提取后,选取Hamilton PRP-X100离子交换色谱柱(250 mm×4.1 mm,10μm),40 mmol/L的磷酸氢二铵为流动相,在16 min内,5种硒形态完全达到基线分离。5种硒形态在线性范围内相关系数R为0.9990~0.9999;加标回收率为76.1%~108%;检出限分别为硒代胱氨酸0.35μg/L、甲基-硒代半胱氨酸0.46μg/L、亚硒酸0.26μg/L、硒代蛋氨酸0.64μg/L、硒酸3.06μg/L;方法应用于富硒黑木耳中硒形态的分析,精密度高、重现性好、方法稳定、准确可靠,是测定富硒黑木耳中硒形态含量的有效方法。     

金作保护剂铅试金分离富集石墨炉原子吸收光谱法测定矿石中痕量铑

铑矿石是获取铑的重要来源,但矿石中的铑含量极低,且分布不均匀,准确测定其含量一直是分析测试中的难题。本研究建立了一种可高效富集矿石中铑元素的铅试金——石墨炉原子吸收光谱分析方法。采用金作保护剂,铅试金分离富集矿石中的铑,形成的金-铑合金用王水溶解,石墨炉原子吸收光谱法进行测定。实验结果表明：熔剂配比m（硼砂）：m（纯碱）：m（黄丹粉）：m（淀粉）=5:5:10:1,加入15mg金做为保护剂,灰吹温度900℃,可完全富集50 μg铑。用石墨炉原子吸收光谱仪进行检测,方法的相对标准偏差RSD（n=11）为6.97%～11.23%,线性范围为0.17～50 μg?L-1,加标回收率为99.36%～100.94%,10倍于铑的其他共存贵金属对测定无干扰。方法准确、可靠、简便,可用于矿石样品中铑的日常分析。本研究对铑资源勘探开采及铑矿物的综合利用研究具有重要意义。     

微波消解-电感耦合等离子体发射光谱(ICP-OES)法测生物质中的碱金属和碱土金属

为研究并解决测试生物质样品中碱金属和碱土金属含量的干扰,采用微波消解-电感耦合等离子体发射光谱(ICP-OES)法对生物质中的碱金属和碱土金属钾、钙、钠、镁元素进行测定,考察了样品消解后不同的酸体系,共存元素干扰对钾、钠、钙、镁含量测定的干扰研究。经过研究表明,接近分析标准曲线酸浓度的样品干扰小,铅、铟、钛、锰元素对钠元素测定造成干扰,砷、铜、镉对钙元素测定干扰,铝对钾元素测定有干扰,镁测定不受共存元素干扰影响,运用干扰系数法可以减少共存元素对测定元素的误差。各待测元素标准曲线相关系数大于0.9996,检出限为0.0014~0.023 mg/L,玉米芯各元素的相对标准偏差为0.98%~1.9%,加标回收率为80.2%~106%;西瓜皮的各元素相对标准偏差为0.91%~2.3%,加标回收率为85.3%~106%。方法用于测定国家标准物质GBW07603,各元素结果均在标准值参考范围内。方法用于测定生物质中碱金属和碱土金属的结果,用t检验法与离子色谱测定值进行比对,结果无显著性差异。     

Evaluating the antimicrobial activity and cytotoxicity of polydopamine capped silver and silver/polydopamine core-shell nanocomposites

Fabrication of bioactive nanomaterials with improved stability and low toxicity towards healthy mammalian cells have recently been a topic of interest. Bioactive metal nanomaterials such as silver nanoparticles (AgNPs) tend to lose their stability with time and become toxic to some extent, limiting their biological applications. AgNPs were separately encapsulated and loaded on the surface of a biocompatible polydopamine (PDA) to produce Ag-PDA and Ag@PDA nanocomposites to unravel the issue of agglomeration. PDA was coated through the self-polymerization of dopamine on the surface of AgNPs to produce Ag-PDA core-shells nanocomposites. For Ag@PDA, PDA spheres were first designed through self-polymerization of dopamine followed by in situ reduction of silver nitrate (AgNO3) without any reductant. AgNPs sizes were controlled by varying the concentration of AgNO₃. The TEM micrograms showed monodispersed PDA spheres with an average diameter of 238 nm for Ag-PDA and Ag@PDA nanocomposites. Compared to Ag@PDA, Ag-PDA nanocomposites have shown insignificant toxicity towards human embryonic kidney (HEK-293T) and human dermal fibroblasts (HDF) cells with cell viability of over 95% at concentration of 250 µg/mL. A excellent antimicrobial activity of the nanocomposites was observed; with Ag@PDA possessing bactericidal effect at concentration as low as 12.5 µg/mL. Ag-PDA on the other hand were only found to be bacteriostatic against gram-positive and gram-negative bacteria was also observed.     

Graded regulation technology for enhanced oil recovery and water shutoff in pore-cavity-fracture carbonate reservoirs

Although a single type of chemical agent (eg, gels, microspheres, surfactants, etc.) has achieved some effects in enhanced oil recovery of carbonate reservoirs, for pore-cavity-fracture carbonate reservoirs, the use of a single type of chemical agent does not perform well. The main objective of this study is to study the effect of different types of chemical agents in enhanced oil recovery of complex carbonate reservoirs. In order to determine the screening principle of chemical agents, the types of water channeling in the North Troyes reservoir were analyzed. For complex fractures, step by step plugging, multi-agent and multi-slug comprehensive intervention is carried out to ensure the plugging of high-permeability channels and inhibit the seepage of large channels. It can plug channeling fracture channel, adjust secondary dominant channel and reduce matrix flow resistance, so as to expand macroscopic swept volume and improve microscopic water flooding efficiency. The results show that it is difficult to comprehensively control water channeling in pore-cave-fracture carbonate reservoir, and the reservoir heterogeneity in the test area can be improved by mixing different types of control and flooding agents and carrying out deep profile control. The plugging rate of gel is 97.18 %, and the oil–water selection ratio is 0.45 in fractured core; the expansion rate of nano - microspheres is more than 3 times; the wetting modifier can improve the imbibition oil displacement efficiency by 14.76%, and the test result shown that nano - microspheres and wetting modifier have good synergistic oil displacement effect. The field application result shown that daily oil production of oil well in the test area increased by 5.0 m³/d and the daily water rate decreased by 19.0% compared with that before the control flooding. The findings of this study can help for better understanding of enhanced oil recovery in pore-cave-fracture carbonate reservoir.     

One pot synthesis of chromium incorporated SBA-16 under acid medium-Application in the selective oxidation of benzyl alcohol derivatives

Cr-SBA-16 mesoporous silica heterogeneous catalysts (Si/Cr = 7, 14, and 28) were successfully synthesized by one-pot hydrothermal method at low acidic medium. The catalysts were characterized by means of X-ray diffraction (XRD), N₂ adsorption-desorption at 77 K, Fourier Transform Infrared (FTIR), X-ray photoelectron (XPS) and Diffuse Reflectance UV–Vis (DRS) Spectroscopies, Thermogravimetric analysis (TGA), Scanning electron microscopy (SEM) and Transmission electron microscopy (TEM) techniques. Herein, Cr-SBA-16 catalysts are evaluated in the selective catalytic oxidation of benzyl alcohol derivatives using H₂O₂ as oxidant. From XPS and UV–Vis (DRS) spectroscopies the molar ratios between Cr⁶⁺/Cr³⁺ are found to increase versus chromium loading in the following order: Cr-SBA-16(28) < Cr-SBA-16(14) < Cr-SBA-16(7). Hence the highest Cr⁶⁺ in tetrahedrally environment is observed for Si/Cr = 7. We demonstrated for the first time that the selective catalytic oxidation of benzyl alcohol (BzOH) using H₂O₂ over Cr-SBA-16 occurs through noncompetitive adsorption mechanism and the reaction is pseudo-first order to BzOH. The activity of the reaction depends on the symmetry of chromium species, herein, high activity is observed for tetrahedral chromium species in Cr-SBA-16(7). The absence of any chromium ions in the filtrate shows no chromium leaching from the silica framework.     

用平行双样测定结果相对偏差限值评估方法验证实验重复性限合理性的研究

分析方法标准验证实验得到的分析方法基本性能参数重复性限和再现性限是日常检测工作质控规范重要依据。以环境监测领域土壤、沉积物及固废样品中无机元素分析为例,考察了已颁布执行的标准文本和在生态环境部官网公开征求意见的分析方法标准中重复性限。将重复性限转化为相对偏差后,与日常检测工作中质控限值进行了比较。根据目前现行有效的平行双样测定结果相对偏差限值,方法验证数据有多大比例符合质控要求？根据方法验证结果,平行双样测定结果相对偏差限值有无改进可能？从上述两个角度进行了研究。研究结果表明：土壤、沉积物、固体废弃物中无机元素的测定,不同文献来源相同分析方法标准和不同分析方法标准,其重复性限转化得到的平行测定相对偏差合格率存在明显区别;用平行测定相对偏差限值可以快速判断标准文本中的重复性限是否合理,审核方法验证数据质量是否满足要求。基于已有标准文本方法验证数据,探讨了修改平行测定结果相对偏差限值可行性。     

检验检测服务模式研究

检验检测服务模式发展滞后于检验检测行业发展的重要原因之一就是缺乏针对于服务模式的理论定义。采用概念分析法,以服务模式的定义和检验检测行业的服务特点为逻辑,研究了相关的代表性理论,认为服务模式主要由服务的基本要素和服务的商业模式两方面的内容组成,并深入探讨了检验检测的服务模式,提出了构建检验检测服务模式这一概念的重要意义。     

-电感耦合等离子体质谱法测定硅锰冶炼渣中8种金属元素

实验采用HCl-HNO₃-HF-HClO₄混合酸为消解体系对样品进行前处理,加入1.0 mL盐酸羟胺溶液(100 g/L)溶解残渣,选择合适的同位素,以¹⁰³Rh为内标测定Cr、Co、Ni、Cu、Zn和Cd,以¹⁹³Ir为内标测定Tl和Pb,建立了电感耦合等离子体质谱(ICP-MS)法测定硅锰冶炼渣中8种重金属元素的方法。实验发现,样品前处理选择HCl∶HNO₃∶HF∶HClO₄=5∶5∶5∶1,并在复溶阶段加入1.0 mL盐酸羟胺溶液(100 g/L)可以完全消解样品,实验采用KED模式和干扰系数校正法消除质谱干扰,样品中待测元素的测定结果不受基体成分的干扰。通过绘制校准曲线及测定流程空白,各元素校准曲线的相关系数均大于0.9999,方法检出限为0.006~0.19 mg/kg,方法定量限为0.018~0.57 mg/kg。对硅锰渣实际样品进行测定,各元素的相对标准偏差(RSD,n=11)在0.83%~4.1%,加标回收率为94.7%~106%;经过人员比对实验,相对偏差为-4.54%~4.24%。测定结果稳定可靠,能满足硅锰冶炼渣中8种微量金属元素含量的分析检测要求。     

Anti-corrosion and anti-microbial evaluation of novel water-soluble bis azo pyrazole derivative for carbon steel pipelines in petroleum industries by experimental and theoretical studies

In this research, we investigated the synthesis of a novel water-soluble bis azo pyrazolin-5-one (ABP) which was synthesized efficiently via the regioselective reaction of hydrazine with coumarin hydrazone (CMH). Also, we evaluate their anti-corrosion and anti-bacterial behavior. The inhibition efficiency of ABP in an acidic medium (1.0 M HCl) was evaluated using various electrochemical and surface morphology measurements. The novel bis pyrazole-based azo dye ABP (16 × 10^?6 M) demonstrated a higher protection capacity (93.3 %). Tafel curves revealed that ABP was a mixed-type inhibitor. The adsorption of ABP on the C-steel (CS) surface is proven by the alteration in (R_ct and C_dl) impedance characteristics and obeyed the Langmuir isotherm model. SEM/EDX, AFM, and XPS surface examinations confirmed the enhancement of an adsorbed film protects the CS surface from acid corrosion at the appropriate dose. Furthermore, theoretical calculations using DFT and MC simulations were performed to identify the active sites on ABP molecules in charge of the adsorption and surface protection of the CS. The adsorption of bis pyrazole-based azo dye on the metal surface explained the protection mechanism. Moreover, the ABP screened for its antimicrobial activity against sulfate-reducing bacteria (SRB), and the calculated inhibition efficiency was 100 %. The current work presents significant results in manufacturing and producing novel water-soluble bis pyrazole-based azo dye derivative with high anti-corrosion and anti-microbial efficiency.