铝基火花源发射光谱仪测定MB1镁合金中锰含量

建立了用铝基体火花源原子发射光谱仪现有通道硬件测定镁合金(MB1)中锰元素含量的方法.方法线性相关系数为0.967 6,RSD为1.66%.对8个未知样品进行了测试,结果与化学分析方法所得结果一致.     

Mass spectrometric profiling of flavonoid glycoconjugates possessing isomeric aglycones

In fields such as food and nutrition science or plant physiology, interest in untargeted profiling of flavonoids continues to expand. The group of flavonoids encompasses several thousands of chemically distinguishable compounds, among which are a number of isobaric compounds with the same elemental composition. Thus, the mass spectrometric identification of these compounds is challenging, especially when reference standards are not available to support their identification. Many different types of isomers of flavonoid glycoconjugates are known, i.e. compounds that differ in their glycosylation position, glycan sequence or type of interglycosidic linkage. This work focuses on the mass spectrometric identification of flavonoid glycoconjugate isomers possessing the same glycan mass and differing only in their aglycone core. A non‐targeted HPLC‐ESI‐MS/MS profiling method using a triple quadrupole MS is presented herein, which utilizes in‐source fragmentation and a pseudo‐MS³ approach for the selective analysis of flavonoid glycoconjugates with isomeric/isobaric aglycones. A selective MRM‐based identification of the in‐source formed isobaric aglycone fragments was established. Additionally, utilizing the precursor scanning capability of the employed triple quadrupole instrument, the developed method enabled the determination of the molecular weight of the studied intact flavonoid glycoconjugate. The versatility of the method was proven with various types of flavonoid aglycones, i.e. anthocyanins, flavonols, flavones, flavanones and isoflavones, along with their representative glycoconjugates. The developed method was also successfully applied to a commercially available sour cherry sample, in which 16 different glycoconjugates of pelargonidin, genistein, cyanidin, kaempferol and quercetin could be tentatively identified, including a number of compounds containing isomeric/isobaric aglycones. Copyright © 2015 John Wiley & Sons, Ltd.     

An anion effect on the separation of AgI-containing melts using sound waves

Sound velocities in molten ((LiF + AgI)) and ((LiBr + AgI)) mixtures have been measured to investigate the relationship between the sound velocity and the temperature and the role of the anion in the (liquid + liquid) phase transition. Our results show that the ((LiBr + AgI)) system is biphasic between the melting point and T = 984 K and becomes monophasic above this temperature. We show that the upper consolute critical temperature for the AgI-containing melts increases with decreasing anion size in the series F⁻ > Cl⁻ > Br⁻. The ((LiF + AgI)) melt remains biphasic at all temperatures investigated up to T = 1218 K. The temperature coefficients for the sound velocities in the upper and lower phases of the ((LiBr + AgI)) system have opposite signs because of the superposition of the temperature and composition factors. The difference between the magnitudes of the velocities for the coexisting phases decreases exponentially with increasing temperature and is described by a critical exponent of 0.85 for the ((LiBr + AgI)) melt near the critical temperature. This value is 15% less than that found for alkali halide melts, in which long-range Coulomb forces between ions prevail. This difference may result from the fact that silver halides are intermediate between the typical ionic salts and the fully covalently bonded ones.     

不同碳源对产甲烷生物阴极性能的影响

以"H"型电池为主体装置,考察和比较了有机和无机碳源对产甲烷生物阴极启动期和稳定运行期性能的影响.结果表明,有机碳源可以加速产甲烷生物阴极的形成,并使其在稳定运行期维持较高的运行性能;有机碳源条件下所形成的产甲烷生物阴极具有较好的电化学活性,当阴极电势为-0.75 V(vs.SHE)时,其电流密度可达(2.34±0.15)A/m2;通过投加有机碳源,可以实现CO2(或HCO-3)的原位供给,与无机碳源直接供给方式相比,可在一定程度上缓解气液传质限制,提高微生物的生长速率,最终使产甲烷生物阴极表面生物量是无机碳源培养下的4倍多.从微生物分析角度解释了有机碳源提高产甲烷生物阴极性能的原因.     

Manipulation with sound and vibration: A review on the micromanipulation system based on sub-MHz acoustic waves

Manipulation of micro-objects have been playing an essential role in biochemical analysis or clinical diagnostics. Among the diverse technologies for micromanipulation, acoustic methods show the advantages of good biocompatibility, wide tunability, a label-free and contactless manner. Thus, acoustic micromanipulations have been widely exploited in micro-analysis systems. In this article, we reviewed the acoustic micromanipulation systems that were actuated by sub-MHz acoustic waves. In contrast to the high-frequency range, the acoustic microsystems operating at sub-MHz acoustic frequency are more accessible, whose acoustic sources are at low cost and even available from daily acoustic devices (e.g. buzzers, speakers, piezoelectric plates). The broad availability, with the addition of the advantages of acoustic micromanipulation, make sub-MHz microsystems promising for a variety of biomedical applications. Here, we review recent progresses in sub-MHz acoustic micromanipulation technologies, focusing on their applications in biomedical fields. These technologies are based on the basic acoustic phenomenon, such as cavitation, acoustic radiation force, and acoustic streaming. And categorized by their applications, we introduce these systems for mixing, pumping and droplet generation, separation and enrichment, patterning, rotation, propulsion and actuation. The diverse applications of these systems hold great promise for a wide range of enhancements in biomedicines and attract increasing interest for further investigation.     

Modifications to functional and biological properties of proteins of cowpea pulse crop by ultrasound-assisted extraction

Natural resource depletion, negative environmental effects and the challenge to secure global food security led to the establishment of the Sustainable Development Goals (SDGs). In need to explore underutilized sustainable protein sources, this study aims at isolating protein from cowpea by ultrasound-assisted extraction (UAE), where the techno-functional characteristics of the protein isolates were studied at different sonication conditions i.e., 100 W and 200 W at processing times ranging from 5 to 20 min. The US at 200 W-10 min produced the optimal results for all properties. In this process combination, there was an increase in protein yield, solubility, water-holding capacity, foaming capacity and stability, emulsion activity and stability, zeta-potential, and in-vitro protein digestibility from 31.78% to 58.96%, 57.26% to 68.85%, 3.06 g/g to 3.68 g/g 70.64% to 83.74%, 30.76% to 60.01%, 47.48% to 64.26%, 56.59% to 87.71%, –32.9 mV to −44.2 mV and 88.27% to 89.99%, respectively and particle size dropped from 763 nm to 559 nm in comparison to control. The microstructure and secondary-structure alterations of proteins caused by sonication were validated by SEM images, SDS-PAGE, and FTIR analyses. Sonication leads to acoustic cavitation and penetrate the cell walls, improving extraction from the solid to liquid phase. After sonication, the hydrophobic protein groups were exposed and proteins were partially denatured which increased its functionality. The findings demonstrated that UAE of cowpea protein improved yield, modify characteristics to fit the needs of the food industry, and contribute to achieving SDGs 2, 3, 7, 12, and 13.     

离子选择电极阵列土壤中硝态氮测定

土壤硝态氮反映土壤短期氮素供应水平,实时了解土壤硝态氮的含量为精准农业和农业面源污染防控提供支撑,因此,在线实时检测土壤硝态氮方法突破就显得十分迫切。土壤硝态氮中的硝酸根离子在土壤中的高水溶性和流动性为全固态硝酸根离子选择电极高敏感检测土壤中硝态氮提供了条件,固态硝态氮离子选择电极的离子选择膜反应硝酸根离子在被测溶液中的浓度。采用全固态硝酸根离子选择电极,且与温度电极和pH电极融合组成电极阵列对土壤饱和溶液中的硝态根离子进行检测。设计了高输入阻抗运算放大电路对电极信号进行采集,并通过微处理控制蠕动泵完成土壤硝态氮待测溶液连续流动测量及实时传输结果。实验结果表明,电极响应时间≤15 s,斜率-51.63 mV/decade,线性范围10-5-10-2.2 mol/L,最低检测限10-5.23 mol/L。相对标准差在0.78%-4.47%范围内,加标回收率均在90%-110%以内。与国家标准紫外可见分光光度法测试结果相比,相关系数（R2）为0.9952,为土壤硝态氮在现场检测奠定技术基础。     

常压敞开式质谱离子源发展趋势

近年来常压敞开式离子源凭借快速、原位、实时离子化样品等优势,被广泛应用于样品快速筛查、真伪鉴定、质谱成像等领域,已成为当今离子源的研究热点,受到了学术界及仪器制造、化学和生物分析等相关产业界的广泛关注。目前,该类离子源朝着克服基体效应、提高样品表面定位能力及增加离子传输距离等方向发展。本文主要介绍了可以很好解决上述问题并具有代表性的三种常压敞开式离子源:电喷雾萃取离子源(EESI)、介质阻挡放电离子源(DBDI)及空气动力辅助离子源(AFAI),重点涉及原理以及在此基础上所做的设计改进和应用进展。     

电喷雾/光电离双源型小型离子阱质谱仪的研制

构建了一套电喷雾/紫外灯双电离源离子阱质谱仪系统,用于气体和液体样品的快速检测.仪器采用非连续大气压进样技术,通过夹管阀装置来同时完成电喷雾离子和中性气态样品的采集和传输.所配备的两种电离源适合不同的分析对象,在应用上具有一定的互补性,其中电喷雾源用于溶液中极性化合物的电离,而紫外电离源主要用于分析气态有机物.本研究选择了苯甲醚、甲苯、2,4-二甲基苯胺、精氨酸、利血平和阿斯巴甜等不同类型的样品,测试了仪器在使用不同电离模式下的工作性能.结果表明,电喷雾源和紫外光电离源可用于不同类型样品的电离,在分析2,4-二甲基苯胺时还能分别生成不同类型的分子离子.两种电离源在工作时互不干扰,既能单独使用,也能同时开启,可根据检测需求随意切换工作模式,获得更全面的样品成分信息.双离子源设计是扩展小型质谱仪应用范围的一种有效途径,这种方案不会明显增加仪器的体积,却能提供更多样化的分析功能,满足对不同类型样品的检测需求.