Analysis of differential strategies to enhance detection of low‐abundance proteins in the bovine serum proteome

Serum‐based biomarkers hold propitious applications for addressing livestock health, and management. However, discovery of protein biomarkers in complex biological fluids like serum is wholly intractable due to the large dynamic range of protein concentrations; that is, ?10–12 high abundance proteins constitute >90% of the total protein content and effectively mask proteomic detection of low‐abundance biomarkers. Toward addressing this limitation, we test a continuous elution size‐based fractionation method, and two approaches that use affinity interaction‐based separation of proteins in preparing bovine serum, and compare liquid chromatography tandem mass spectrometry protein identification to neat serum. Our results identify the high‐abundance proteins in bovine serum, and demonstrate dynamic range compression and improved protein identification with the different enrichment methods. Although these findings indicate the highest protein number identified in bovine serum (445 proteins, all methods combined), and by any single sample processing method (312 proteins) to date, they still remain lower than levels deemed necessary for biomarker discovery. As such, this investigation revealed limitations to resolving the bovine serum proteome, and the need for species‐specific tools for immunodepleting high‐abundance proteins. In concert, this study represents a step toward advancing sample preparation methods for bovine serum biomarker identification.     

高效液相色谱-串联质谱法同时检测牛乳中11种农药残留量

采用高效液相色谱-串联质谱仪,建立一种可以同时检测牛乳中多种农药残留的分析方法。样品经乙腈提取,氯化钠、硫酸镁分层,经过2 次提取后,用C18固相萃取柱净化,流出液旋转蒸发至干后用乙腈复溶后上机测定。采用C18色谱柱进行分离,以5 mmol/L乙酸铵（含0.1%甲酸）-甲醇为流动相进行梯度洗脱,电喷雾离子化模式在多反应监测模式下测定。结果表明：啶虫脒、涕灭威、噻虫胺、甲胺磷、氟酰脲、苯丁锡、螺螨酯、苯醚甲环唑、噻草酮、氰氟虫腙及二甲四氯11 种农药在质量浓度0～100 ng/mL范围内线性良好,相关系数（R2）均大于0.995 0;对不含农药残留的牛乳样品进行3 个添加水平（1、2、4 μg/L）的测定,11 种农药的平均加标回收率为40.2%～99.2%,相对标准偏差均小于18.9%,方法检出限为1.00 μg/L;该方法可以快速、灵敏测定牛乳中11 种 农药残留量。     

变质量力学系统相对运动的Kane方程及其应用

本文给出变质量力学系统相对运动的Kane方程,并由此导出变质量非完整系统相对运动的若干运动微分方程。     

一类变质量问题的一般解法

本文讨论了物体在恒定场中运动时,在一定条件下,物体的质量随时间变化。以雨滴在恒定重力场中的下落过程为例,根据密歇尔斯基运动方程,讨论了质量变化的6种情况,分别得到其运动方程式,并用幂级数法求出解答。     

浙江省松二元立木材积表在千岛湖封山育林地区的适用性检验

随机抽取50株马尾松解析木,经F检验,浙江省松立木二元材积表(二),适用于千岛湖封山育林地区。     

Droplet infiltration and organic matter composition of intact crack and biopore surfaces from clay‐illuvial horizons

The organic matter (OM) in biopore walls and aggregate coatings may be important for sorption of reactive solutes and water as well as for solute mass exchange between the soil matrix and the preferential flow (PF) domains in structured soil. Structural surfaces are coated by illuvial clay‐organic material and by OM of different origin, e.g., earthworm casts and root residues. The objectives were to verify the effect of OM on wettability and infiltration of intact structural surfaces in clay‐illuvial horizons (Bt) of Luvisols and to investigate the relevance of the mm‐scale distribution of OM composition on the water and solute transfer. Intact aggregate surfaces and biopore walls were prepared from Bt horizons of Luvisols developed from Loess and glacial till. The mm‐scale spatial distribution of OM composition was scanned using diffuse reflectance infrared Fourier transform (DRIFT) spectroscopy. The ratio between alkyl and carboxyl functional groups in OM was used as potential wettability index (PWI) of the OM. The infiltration dynamics of water and ethanol droplets were determined measuring contact angles (CA) and water drop penetration times (WDPT). At intact surfaces of earthworm burrows and coated cracks of the Loess‐Bt, the potential wettability of the OM was significantly reduced compared to the uncoated matrix. These data corresponded to increased WDPT, indicating a mm‐scaled sub‐critical water repellency. The relation was highly linear for earthworm burrows and crack coatings from the Loess‐Bt with WDPT > 2.5 s. Other surfaces of the Loess‐Bt and most surfaces of the till‐derived Bt were not found to be repellent. At these surfaces, no relations between the potential wettability of the OM and the actual wettability of the surface were found. The results suggest that water absorption at intact surface structures, i.e., mass exchange between PF paths and soil matrix, can be locally affected by a mm‐scale OM distribution if OM is of increased content and is enriched in alkyl functional groups. For such surfaces, the relation between potential and actual wettability provides the possibility to evaluate the mm‐scale spatial distribution of wettability and sorption and mass exchange from DRIFT spectroscopic scanning.     

便携式风力灭火机的人机工程学评价

为研究便携式风力灭火机的振动、噪声和质量对操作人员生理和心理负荷的影响,通过试验对便携式风力灭火机(国产6MF-30和日本产HB2302)的把手振动和耳旁噪声进行测试,选取心率和反应时间对便携式风力灭火机进行人机工程学评价。结果表明:6MF-30的振动加速度、耳旁噪声、心率增加比、反应时间均大于HB2302;风力灭火机的耳旁噪声随着振动加速度的增加而增加,振动和噪声共同作用于操作人员,难以区分开,因此,将振动和噪声的综合作用视为一个影响因子,取得了较好的分析效果;质量和振动-噪声对心率增加比有显著影响,对反应时间没有显著影响,质量对心率的影响要大于振动-噪声。建议重新对6MF-30进行设计,重点考虑质量和减振降噪,发动机选择功率适中且质量轻的,前把手选择塑料作为主要材料。      

测定植物叶片滞留PM2.5等大气颗粒物质量的方法

以7种重庆市绿化基调树种为例,将滤膜过滤称质量优化为滤膜分级(10、2.5 μm)过滤称质量,并与数学比例关系换算相结合,建立了一种新的测定植物叶片滞留细颗粒物(PM2.5,直径≤2.5 μm)等大气颗粒物质量的方法。该方法不直接进行PM2.5的收集和称量,回避了单独采用滤膜过滤称质量时,由于PM10或PM2.5中粒径、质量极其微小的颗粒被滤掉而导致PM10或PM2.5不能完全被收集和准确称量的缺点。该方法所需仪器设备简单,普通实验室便具备,同时也克服了利用显微仪器观察并量算植物叶片滞留颗粒物的局限性。用通过120目筛的土壤样品进行准确性和稳定性检验,该方法准确可靠,具有可操作性。应用该方法测定了7种重庆市绿化基调树种叶片滞留PM2.5等大气颗粒物质量,为评价不同树种和林分结构的滞尘功能差别奠定了技术基础。      

不同品种苦荞麦种子形态性状差异及其化学成分研究

为探究川荞1号、西荞1号、米荞1号以及迪苦4个品种苦荞麦种子形态性状差异并鉴定其化学成分, 观察了不同品种苦荞麦种子的形态差异,同时进行千粒重和含水量的测试,并采用超高效液相色谱-四极杆-静电场轨道阱高分辨质谱(UPLC-Q-Orbitrap HRMS)技术,快速分析鉴定了4个品种苦荞麦的化学成分。结果表明： 4个品种苦荞麦种子形状、色泽等均存在明显差异,川荞1号主要呈黑色长锥形,而其他3种荞麦主要呈短锥形,米荞1号果皮呈米白色,迪苦果皮呈灰褐色;同时,4个品种苦荞麦种子千粒重和含水量亦存在显著差异;此外,4个品种苦荞麦中除个别成分有无之外,整体离子流峰形基本一致,共分析鉴定了包括黄酮类、氨基酸类、生物碱类等27个化合物。研究结果可为苦荞麦优良品种选育、优选质量控制指标提供较为全面的理论依据和参考,对进一步开发利用苦荞麦资源具有一定的指导意义。