QuEChERS-高效液相色谱-串联质谱法同时测定 果蔬中26种植物生长调节剂残留

目的建立高效液相色谱-串联质谱法同时测定果蔬中26种植物生长调节剂残留量的检测方法。方法样品经QuEChERS法预处理,用含1%甲酸的乙腈溶液提取,无水硫酸镁和十八烷基硅烷(C_(18))粉末净化,以Agilent Poroshell 120 EC-C_(18)(3.0 mm×100 mm,2.7μm)为分析色谱柱,甲醇和5 mmol/L乙酸铵-0.1%甲酸缓冲液作为流动相进行梯度洗脱分离,采用电喷雾多反应监测模式,基质匹配标准溶液外标法定量。结果 26种植物生长调节剂线性良好,线性相关系数均0.990,该方法的检出限在1~10μg/kg之间,以豆芽和苹果为代表性基质进行3个水平加标回收实验,回收率在80.81%~118.4%之间,相对标准偏差(RSD)为0.9%~14.8%。结论该方法灵敏度高,定性、定量准确,简便高效,可适用于多种水果和蔬菜中26种植物生长调节剂残留的同时检测要求。     

改良QuEChERS结合超高效液相色谱-四极杆/静电场轨道阱高分辨质谱法测定果蔬中15种植物生长调节剂残留

基于改良的QuEChERS方法,建立超高效液相色谱-四级杆/静电场轨道阱高分辨质谱法(UPLC-Q-Orbitrap HRMS)快速筛查和测定果蔬中15种植物生长调节剂残留的方法。样品以1%乙酸乙腈提取,多壁碳纳米管(MWCNTs)净化,采用Hypersil GOLD aq C₁₈色谱柱(2.1 mm×100 mm,1.9 μm)进行分离,乙腈和水(含0.1%甲酸-5 mmol/L甲酸铵)为流动相梯度洗脱,质谱采用全扫描/数据依赖的二级扫描模式,基质匹配校准曲线定量。结果显示:15种化合物在2.0~500.0 μg/L范围内,线性关系良好(r>0.990);在3个加标水平下,平均回收率为70.3%~107.2%,相对标准偏差(RSD)为1.4%~9.9%,定量限为10.0~20.0 μg/kg。该方法简单,灵敏度高,准确可靠,可对果蔬中植物生长调节剂进行快速筛查和定量分析。     

Importance of growth hormones and temperature for physiological regulation of dormancy and sprouting in onions

Onion is one of the most cultivated crops, and its production is increasing worldwide. Proper handling and storage will add huge benefits to the supply of onion to meet the demand of consumers. For storage, it is important to understand onion physiology from the day it was harvested from the field until it reaches the market. This review summarizes the scientific literature related to the physiology of the onion bulb with respect to growth regulators, temperature, and chemical controls. The biochemical changes that occur during dormancy break and sprouting have been discussed in detail. The three main environmental factors that can influence onions during storage are temperature, humidity, and composition of the atmosphere in the storage area. Among these factors, temperature plays a paramount role in the physiology of onion during pre- and postharvest storage. Particular emphasis was given to plant growth hormones (endogenous and exogenous) and their consequent effects with respect to dormancy, sprouting, and biochemical changes that occur in onions.     

有碱无碱工艺在云南胶磷矿选矿中的适应性

云南中低品位胶磷矿选别富集主要采用正—反浮选工艺流程,正浮选作业一般在碱性(pH 10.5)介质中完成,从试验指标、药剂成本等综合评价得知,硅钙质胶磷矿采用无碱工艺更合理,风化程度高的钙硅质胶磷无碱和有碱工艺都可以,硅质胶磷矿只能采用有碱工艺。有针对性地根据矿石性质选用合理的矿浆pH值调整剂,在取得相当技术指标的前提下,可以节约药剂成本、简化回水处理工艺,对于合理开发利用云南磷资源具有深远的意义。     

组合调整剂对铁矿物与石英的浮选分离影响

东鞍山铁矿石因矿石中碳酸盐含量高而难以选别,为寻找适宜的浮选组合调整剂及其用量,提高选别指标,分别以淀粉和CaCl₂及其组合为调整剂考察了添加调整剂对赤铁矿、磁铁矿、菱铁矿、铁白云石、石英单矿物可浮性的影响。结果表明：仅添加单一淀粉或CaCl₂均不能实现铁矿物与石英的分离,当淀粉与CaCl₂组合使用且pH>11时,石英与铁矿物可浮性差异较大。对东鞍山现场铁品位为50.88%的混磁精采用淀粉与CaCl₂为组合调整剂,RA715为捕收剂经1粗1精浮选试验,获得了铁品位为64.06%、回收率为61.96%的浮选精矿,与现场工艺指标相比,铁品位和回收率分别提高了1.33和6.01个百分点。     

核电封头五轴数控加工刀具路径规划研究

核电封头机械加工余量大,并且球面上非对称的分布这若干管嘴端面,这给高效刀具路径规划造成了极大的难度。在NURBS方法基础上,针对核电水室封头等形状复杂大型工件,从加工效率和稳定性的角度,建立环形铣刀加工曲面的运动几何学模型并应用加工域规划法进行刀具路径规划。合理的刀具路径规划可以有效的避免刀具干涉,缩短刀具路径,提高加工精度。     

Small‐Molecule Regulators of Autophagy and Their Potential Therapeutic Applications

Autophagy is a highly conserved process in which damaged proteins and organelles are sequestered in double‐membrane autophagosomes and delivered to lysosomes for degradation and recycling. As an efficient response to cellular stress, autophagy is essential for the maintenance of cellular homeostasis. Defective autophagy is associated with a variety of diseases, including cancer. This article summarizes current knowledge about the molecular mechanism of autophagy and its role in tumorigenesis. Particular focus is placed on the development of small‐molecule regulators of autophagy and their potential application as anticancer therapeutic agents.     

Enzymic production of aldopentauronic acid and use as a bioregulator in plant airlift bioreactors

Neutral and acidic oligosaccharides were obtained from birchwood xylan by treatment with an endoxylanase, family 11 class, from Sporotrichum thermophile. The main acidic xylooligosaccharide (aldopentauronic acid) was separated from the hydrolysate by anion-exchange and size-exclusion chromatography and the structure was determined by 13C NMR spectroscopy. The aldopentauronic acid yield was 25% (w/w) of the total solubilized sugars. The addition of purified aldopentauronic acid at a concentration of 5 mg/l to cucumber liquid culture in 2.5-l airlift bioreactors caused in increase in both the number of regenerants and their fresh weight.     

AGC of a multi-area multi-source hydrothermal power system interconnected via AC/DC parallel links under deregulated environment

This paper proposes the automatic generation control (AGC) of an interconnected multi-area multi-source hydrothermal power system under deregulated environment. The two equal control areas with hydro and thermal generating power sources are interconnected via AC/DC parallel links. The optimal proportional integral (PI) regulators are designed for the proposed power system to simulate all power market transactions which are possible in a restructured power system. The concept of DISCO participation matrix (DPM) is harnessed to simulate the transactions. Eigenvalue study is conducted to assess the effect of AC/DC parallel links on system performance. The study is also conducted, considering appropriate generation rate constraints (GRCs) for thermal and hydro generating sources. Further, the dynamic responses of the proposed multi-source hydrothermal power system are compared with single-source thermal–thermal power system and it has been ascertained that the responses of proposed power system are sluggish with large overshoots and settling times. Finally, the study is extended to frame and implement optimal PI regulators for the first time for the AGC of a conventional two-area non-reheat thermal power system with governor dead-band nonlinearity. The superiority of the optimal PI regulators has been established by comparing the results with recently published best claimed craziness based particle swarm optimization (CRAZYPSO) and hybrid bacterial foraging optimization algorithm-particle swarm optimization (hBFOA-PSO) algorithms based PI controller tuned for the same interconnected power system.