Kinetics Analysis for the Parallel Reaction of Binary Rare Earth with Tribromoarsenazo

The overall reaction was determined on the basis of the dissociation constant of TBA and the ratio of the ligand to the rare earth ion in the complex.The rate law,rate constants and acitivition energies for the reaction of La^(3+),Gd^(3+)and Ho^(3+)with TBA were studied.It is shown in the study that prerequisites for performing differential rate analysis for binary rare earths with TBA are that the pseudo-first-order parallel reaction mechanism should be conformed with,no multinuclear complex would be formed and the co-coloration effects could be neglected.

Analysis of Fatty Acid in Biological Samples Using Liquid Chromatography–Quadrupole-Orbitrap Mass Spectrometry Under Parallel Reaction Monitoring Mode

Fatty acids(FAs)are an important class of functional small molecules and participate in a variety of life biological processes.This experiment proposed a liquid chromatography–quadrupole-Qrbitrap mass spectrometry(LC–Q-Orbitrap MS)method to perform FA profiling under parallel reaction monitoring(PRM)acquisition mode.The FA was derivatized by 2-dimethylaminoethylamine(DMED)to increase the ionization e fficiency and provide the characterized fragment pattern.The mass spectra obtained from full scan,multiple ion monitoring(MIM),and PRM were compared.The results showed that the protonated ion of FA+DMED–H2O was detected and the neutral loss of 45.06 Da was observed in the tandem mass spectrum.The PRM method provided the highest selectivity and sensitivity for FA detection with the help of accurate mass weight and specific neutral loss-based fragments.The method validation was performed using the FA standards and pooled quality control serum sample,which showed that the established method had good repeatability,stability,and linearity.Finally,the developed method was successfully applied to analyze the rat serum and brain tissue samples for the drug e ffi-cacy evaluation of gross saponin of Tribulus terrestris L.fruit(GSTTF)against middle cerebral artery occlusion(MCAO)-induced ischemic stroke.This method has extensive practicability and great potential in the detection of FA,especially for the analysis of samples with complex matrices.

Defective g-C_(3)N_(4)supported Ru_(3)single-cluster catalyst for ammonia synthesis through parallel reaction pathways

Designing catalyst to achieve ammonia synthesis at mild conditions is a meaningful challenge in catalysis community.Defective g-C_(3)N_(4)nanosheet supported single-cluster ruthenium and iron catalysts were investigated for their ammonia synthesis performance.Based on density functional theory(DFT)calculations and microkinetic simulations,Ru_(3)single-cluster anchored on defective g-C3N4 nanosheet(Ru_(3)/Nv-g-C_(3)N_(4))has a turnover frequency(TOF)5.8 times higher than the Ru(0001)step surface at industrial reaction conditions of 673 K and 100 bar for ammonia synthesis.In other words,similar TOFs could be achieved on Ru_(3)/Nv-g-C_(3)N_(4)at much milder conditions(623 K,30 bar)than on Ru(0001)(673 K,100 bar).Our computations reveal the reaction proceeds parallelly on Ru_(3)/Nv-g-C_(3)N_(4)through both dissociative and alternative associative mechanisms at typical reaction conditions(600–700 K,10–100 bar);N–N bond cleavage of*N2 and*NNH from the two respective pathways controls the reaction collectively.With increasing temperatures or decreasing pressures,the dissociative mechanism gradually prevails and associative mechanism recedes.In comparison,Fe_(3)/Nv-g-C_(3)N_(4)catalyst shows a much lower catalytic activity than Ru3/Nv-g-C_(3)N_(4)by two orders of magnitude and the reaction occurs solely through the dissociative pathway.The finding provides a prospective candidate and deepens the mechanistic understanding for ammonia synthesis catalyzed by single-cluster catalysts(SCCs).

ESTIMATION OF OVERALL EFFECTIVENESS FACTORS FOR PARALLEL CATALYTIC REACTIONS

Approximate analytical expressions of overall effectiveness factors for parallel catalytic reac-tions occurring in a spherical catalyst pellet with both internal and external mass transfer resistancesare obtained after taking the information given by asymptotic solutions valid for small and largevalues of Thiele moduli.This approximate procedure is feasible for power law as well asLangmuir-Hinshelwood kinetics and the agreement between the approximation and the numerical re-sults is good enough for practical purposes.Moreover,the method does not require any iterative ortrial-and-error computation,and can be conveniently applied in most practical calculations for reac-tors giving reliable results.

DIA-based proteome profiling with PRM verification reveals the involvement of ER-associated protein processing in pollen abortion in Ogura CMS cabbage

Ogura cytoplasmic male sterility(Ogura CMS)is extensively applied in hybrid seed production in cruciferous crops.However,the posttranscriptional molecular basis of Ogura CMS in cruciferous crops remains elusive.Here,a data-independent acquisition-based proteomic approach coupled with a parallel reaction monitoring-based targeted proteomic assay was used to analyze the proteome dynamics of Ogura CMS cabbage line RM and its maintainer line RF during floral bud development to obtain insights into the mechanism underlying Ogura CMS in cruciferous crops.A total of 9162 proteins corresponding to 61464 peptides were identified in RM and RF floral buds.The proteomic fluctuation of RM was weaker than that of RF.Differences in protein expression between RM and RF gradually enlarged with floral bud development.Fifteen continually up-regulated and eight continually down-regulated proteins were found in RM relative to RF throughout floral bud development.Differentially expressed proteins between RM and RF during floral bud development were implicated in the endoplasmic reticulum(ER)-associated protein processing pathway,in which most of them exhibited down-regulated expression in RM.These data suggest that ER-associated protein processing may be involved in pollen abortion in Ogura CMS cabbage by inhibiting the expression of critical factors.Our findings not only deepen the understanding of the molecular mechanisms of Ogura CMS in cruciferous crops but also provide better guidance for applying Ogura CMS in the hybrid breeding of cruciferous crops.

间隔织物双剑杆织机平行打纬机构箱体的振动分析

针对双剑杆织机共轭凸轮与四连杆组合的平行打纬机构箱体随着织机转速的提高产生强烈振动,影响打纬精度和可靠性的问题,采用理论分析与虚拟仿真结合的方法对打纬机构及箱体进行动应力和振动特性研究。建立了平行打纬机构的动态静力分析方程,运用ADAMS软件对机构进行多体动力学仿真,求解箱体所受的支反力;构建箱体—弹簧阻尼—柔性基础的系统模型,分析箱体在竖直方向的受迫振动,并在仿真过程中探索减小箱体振动的方法。研究结果表明:摆臂轴孔处箱体所受支反力峰值最大,打纬推程阶段箱体的受力最为集中;当凸轮轴转速为260 r/min时齿轮啮合频率与箱体一阶固有频率相等,会产生共振,应避免使用这一转速工作;箱体在竖直方向上产生周期性振动,增加螺栓个数和附加动力减震器有助于改善箱体的振动特性,振幅分别减少38%和23%。

褐黄血蜱脂肪酸结合蛋白对褐黄血蜱卵及其原生质蛋白影响的研究

为了解蜱类脂肪酸结合蛋白(FABP)及其基因的结构和功能,本研究基于褐黄血蜱转录组文库中的Contig 879序列设计引物,采用cDNA末端快速扩增技术(RACE)扩增其两翼缺失部分,拼接后得到编码褐黄血蜱FABP (HfFABP)的全长cDNA序列;采用qPCR法检测该基因在褐黄血蜱的不同发育阶段、不同组织器官中的转录水平;采用平行反应监测(PRM)法分析HfFABP dsRNA干扰对褐黄血蜱产卵和孵化,以及卵原生质蛋白的影响。结果显示,HfFABP的cDNA全长1 443 bp,ORF长396 bp,编码132个氨基酸的多肽。HfFABP基因在雌蜱中的转录水平高于幼蜱、若蜱和雄蜱;在蜱的卵巢、中肠和体壳中的转录水平高于其在唾液腺中的转录水平;吸血使HfFABP基因的转录水平升高。HfFABP dsRNA干扰使蜱产卵减少,其中约30%的卵大小不均、蜡质增多、塌瘪易裂;表观正常的卵孵化率降低,原生质中的FABP、卵黄蛋白原(Vitellogenin)、弹性蛋白酶抑制剂(Neutrophil elastase inhibitor)、天冬氨酸蛋白酶(Aspartic protease)和热休克蛋白83 (Heat shock protein 83)等12种蛋白的丰度大幅下降(P<0.01、P<0.05)。上述结果首次表明HfFABP在蜱卵发育过程中发挥重要作用,本研究为HfFABP在抑制雌蜱生殖中的应用提供科学依据。

基于UHPLC-Q-Exactive orbitrap MS结合PRM技术快速鉴定棉秆的化学成分

【目的】系统研究棉秆的化学成分,为其深入开发利用奠定基础。【方法】采用超高效液相色谱-四极杆-静电场轨道阱高分辨质谱(ultra-high-performance liquid chromatography-quadrupole-electrostatic field orbitrap high resolution mass spectrometry,UHPLC-Q-Exactive orbitrap MS),色谱柱为Thermo Scientific Hypersil GOLD^(TM)aQ(100 mm×2.1 mm,1.9μm),流动相为0.1%甲酸水溶液(A)-乙腈(B),流速为0.3 m L·min^(-1),柱温为40℃,进样量为2μL;质谱采用电喷雾离子源,在正、负离子模式下采用一级母离子全扫描和数据依赖性前三强二级子离子扫描并结合平行反应监测(parallel reaction monitoring,PRM)模式采集数据。【结果】在棉秆中共鉴定了102种化合物,包括有机酸类化合物48种、黄酮及其苷类化合物13种、萜类化合物10种、核苷酸类化合物8种、氨基酸类化合物8种、香豆素类化合物3种、生物碱类化合物2种、其他化合物10种。其中,92种为首次在棉秆中发现。【结论】建立的UHPLC-Q-Exactive orbitrap MS结合PRM方法操作简便,灵敏度高,分析速度快,鉴定了棉秆中102种化合物,首次鉴定了92种,为棉秆的深入开发利用奠定基础。

标志物研究中常用蛋白组学质谱方法的定量准确性评估

在疾病发生过程中,蛋白质的表达水平、修饰状态或相互作用模式的变化有可能反映病理状态或疾病进展,因此蛋白质常被用作疾病标志物.基于质谱的蛋白质组学发现了大量的潜在疾病标志物,这些标志物及其质谱检测方法能否进一步推广至临床检测,定量准确性和稳定性是关键.本文合成了32条标准肽段,对数据非依赖性采集(DIA)、多反应监测(MRM)及平行反应监测(PRM) 3种有潜力在临床质谱方面大规模应用的定量方法进行了比较和评估.将肽段稀释成4个不同的浓度来模拟不同丰度的实际样本,用以上3种质谱方法采集数据后,比较了肽段发现率、标准曲线线性、日间和日内精密度及保留时间(RT)漂移等情况,总结了3种定量方法各自的优缺点和潜在应用方向.结果表明,MRM定量方法最适合临床应用,在于其优异的日间日内稳定性、灵敏度和定量精度;PRM适合科研方向靶向定量,因其拥有最高灵敏度和较高稳定性定量精度;而DIA由于高通量而依赖于软件和算法解析,定量数目多的同时,对于特定肽段定量准确性比PRM/MRM差.

具射流反作用力喷砂除锈并联机构自抗扰控制

针对由喷砂除锈并联机构末端喷枪射流反作用力造成的非匹配干扰问题,提出一种喷砂除锈并联机构非线性自抗扰控制方法。采用解析法对并联机构进行运动学分析,采用拉格朗日法建立考虑非匹配干扰的并联机构动力学模型;通过应用等效输入干扰技术将系统的非匹配干扰转换为位于控制输入通道的匹配干扰,并与建模误差、关节摩擦力及外部干扰等集总为系统总干扰;设计非线性扩张状态观测器对系统集总干扰进行实时精确估计和补偿,进一步设计基于扩张状态观测器的自抗扰控制,以增强系统对集总干扰的鲁棒性,同时提高其轨迹跟踪控制性能。最后证明闭环系统的稳定性,并基于MATLAB软件和具射流反作用力喷砂除锈并联机构样机,对所提出控制方法进行仿真和样机实验,实验结果验证了所提出方法的有效性。

A Rapid Parallel Synthesis of 2-Dialkylamino-4(3H)-quinazolines

Dialkylamino-4(3H)-quinazolinones 4 were rapidly synthesized by a solution-phase parallel synthetic method, which includes aza-Wittig reaction of iminophosphorane 1 with aromatic isocynate to give carbodiimide 2 and subsequent reaction of 2 with various aliphatic secondary amine in a parallel fashion.

Proteomics-based identification of proteins in tumor-derived exosomes as candidate biomarkers for colorectal cancer

BACKGROUND Colorectal cancer(CRC)is the second leading cause of cancer-related death,with high morbidity worldwide.There is an urgent need to find reliable diagnostic biomarkers of CRC and explore the underlying molecular mechanisms.Exosomes are involved in intercellular communication and participate in multiple pathological processes,serving as an important part of the tumor microenvironment.AIM To investigate the proteomic characteristics of CRC tumor-derived exosomes and to identify candidate exosomal protein markers for CRC.METHODS In this study,10 patients over 50 years old who were diagnosed with moderately differentiated adenocarcinoma were recruited.We paired CRC tissues and adjacent normal intestinal tissues(>5 cm)to form the experimental and control groups.Purified exosomes were extracted separately from each tissue sample.Data-independent acquisition mass spectrometry was implemented in 8 matched samples of exosomes to explore the proteomic expression profiles,and differentially expressed proteins(DEPs)were screened by bioinformatics analysis.Promising exosomal proteins were verified using parallel reaction monitoring(PRM)analysis in 10 matched exosome samples.RESULTS A total of 1393 proteins were identified in the CRC tissue group,1304 proteins were identified in the adjacent tissue group,and 283 proteins were significantly differentially expressed between them.Enrichment analysis revealed that DEPs were involved in multiple biological processes related to cytoskeleton construction,cell movement and migration,immune response,tumor growth and telomere metabolism,as well as ECM-receptor interaction,focal adhesion and mTOR signaling pathways.Six differentially expressed exosomal proteins(NHP2,OLFM4,TOP1,SAMP,TAGL and TRIM28)were validated by PRM analysis and evaluated by receiver operating characteristic curve(ROC)analysis.The area under the ROC curve was 0.93,0.96,0.97,0.78,0.75,and 0.88(P<0.05)for NHP2,OLFM4,TOP1,SAMP,TAGL,and TRIM28,respectively,indicating their good ability to distinguish CRC tissues from adjacent intestinal tissues.CONCLUSION In our study,comprehensive proteomic profiles were obtained for CRC tissue exosomes.Six exosomal proteins,NHP2,OLFM4,TOP1,SAMP,TAGL and TRIM28,may be promising diagnostic markers and effective therapeutic targets for CRC,but further experimental investigation is needed.

Reconstructed parallel sites enhance the reactive oxygen tolerance of non-noble metal catalyst for durable proton exchange membrane fuel cells

The establishment of reactive oxygen species(ROS) elimination sites in iron-nitrogen-carbon(Fe-N-C) electrocatalysts to achieve durable proton-exchange membrane fuel cells(PEMFCs) performance has attracted broad interest. However, realizing ROS removal efficiency and oxygen reduction reaction(ORR) activity within a single system represents a significant challenge to date. Herein, we demonstrate uniform ROS elimination sites and ORR centers through an electrochemical reconstruction method on the parallel sites of Fe@Ce NC electrocatalyst for durable PEMFC. During the reconstruction process, the Fe sites can retain their original configuration. Meanwhile, the pristine Ce clusters will evolve into more efficient, highly dispersed sites.Furthermore, the reconstructed Fe and Ce sites exhibit favorable energy barriers for the ORR and ROS elimination pathways,respectively, thereby maintaining ORR activity and achieving high ROS tolerance. Consequently, the PEMFC assembled with our catalyst shows only a 2% decay in power density after the accelerated durability test. We anticipate that this parallel structure design will provide new insight into the development of more durable electrocatalysts for PEMFCs.

基于蛋白质组学技术探讨榆栀止血颗粒治疗异常子宫出血大鼠的作用机制

目的:使用蛋白质组学技术研究榆栀止血颗粒对异常子宫出血大鼠蛋白表达的影响,探究其作用机制。方法:除对照组外通过药物致早孕大鼠流产的方法建立实验模型,30只SPF级Wistar妊娠雌鼠随机分为模型组、给药组和对照组,每组10只。给药组连续给予榆栀止血颗粒7 d,于第1、2、3、7天检测各组大鼠出血量。采用定量蛋白质组学分析榆栀止血颗粒对大鼠血清中蛋白表达差异的影响,并分析差异蛋白参与的信号通路。针对筛选出的差异蛋白和信号通路,利用平行反应监测技术进行验证。结果:模型组大鼠从第1天开始子宫出血量较对照组显著增加(P<0.01);与模型组比较,给药组大鼠从第1天开始子宫出血量显著减少(P<0.01)。共定量得到5496个蛋白质。给药组与模型组之间有84个差异蛋白(上调28个,下调56个)。差异蛋白主要富集于PI3K/Akt信号通路、补体和凝血级联、血小板激活等信号通路。选择玻连蛋白、纤溶酶原、丝氨酸蛋白酶抑制剂D1素辅因子Ⅱ等进行PRM验证,验证结果与TMT结果一致。结论:榆栀止血颗粒能够通过调节玻连蛋白、纤溶酶原等蛋白的表达水平,实现对异常子宫出血大鼠的治疗作用。

谈级数相同的平行反应

平行反应也称为竞争反应,是理科化学专业物理化学动力学中教学的重点内容之一,也是物理化学考研中常考内容。平行反应中最简单的一类是具有相同级数的不可逆平行反应。在1-1级平行反应动力学方程推导的基础上,阐述级数相同的平行反应的动力学特点、分析温度对级数相同平行反应的影响以及平行反应表观活化能的计算。最后通过例题解析,让同学们进一步理解和掌握具有相同级数的平行反应,同时为物理化学考研的有效复习提供一定的指向。

基于TMT和PRM技术筛选车叶草苷干预CUMS大鼠海马组织的差异表达蛋白

【目的】基于蛋白质组学探讨车叶草苷对慢性温和应激(chronic unpredictable mild stress,CUMS)抑郁模型大鼠海马组织的保护作用机制,为车叶草苷的开发利用提供依据。【方法】选取45只雄性SD大鼠预饲1周后,随机分为3组:空白组、模型组、车叶草苷组,每组各15只;空白组每笼饲养3只,其他组单笼饲养。试验周期为5周,于试验第3周开始,温和不可预知性刺激同时给药,车叶草苷组按0.070 g/kg BW剂量灌胃给药,空白组、模型组灌服等体积的生理盐水,每天一次。造模完成后提取大鼠海马组织总蛋白,利用同位素串联质谱标签(tandem mass tags,TMT)定量标记技术进行抑郁模型大鼠海马蛋白质组学分析,筛选潜在差异表达蛋白,借助平行反应监测(parallel reaction monitoring,PRM)技术对候选蛋白在海马组织中的表达情况进行靶向验证。【结果】筛选出车叶草苷组、模型组之间6个上调和17个下调的差异表达蛋白;GO功能和KEGG通路富集分析表明,它们主要参与神经活性配体-受体相互作用、互补和协同调节级联、胃酸分泌等信号通路;PRM成功验证缓激肽(BK)、免疫球蛋白(IGHM及ILD)、蛋白酶体激活剂复合物亚基1(PSME1)4个蛋白表达趋势与TMT定量结果一致,可能是车叶草苷调节抑郁的潜在靶标蛋白。车叶草苷通过参与调控神经活性配体-受体相互作用等信号通路的关键靶标、下调BK蛋白表达对神经元发挥直接或间接的保护作用、上调与免疫球蛋白IgG表达显著相关的PSME1蛋白水平产生免疫抑制、使免疫蛋白浓度趋于正常等途径保护海马组织。【结论】车叶草苷可能通过多途径协同作用减轻机体抑郁症状。本研究结果为深入探索CUMS模型病理机制及阐明车叶草苷调控海马组织的蛋白质或通路提供参考。

钠冷快堆多模块蒸汽发生器大泄漏钠水反应事故保护系统关键参数敏感性分析

钠冷快堆采用钠-钠-水三回路设计,当发生传热管破裂后,引起的大泄漏钠水反应事故将威胁二回路的完整性和安全性,设置的保护系统要能够有效保证二回路的完整性。本文以钠冷快堆二回路和多模块蒸汽发生器保护系统为研究对象,建立了大泄漏钠水反应模型,利用钠水反应实验结果对模型进行了验证。模拟了3根传热管发生双端断裂(3-Double-Ended Guillotine,3-DEG)的大泄漏钠水反应过程,分析了二回路的完整性和保护系统的响应。选取保护系统5种关键参数进行敏感性分析,计算其对二回路最高压力和保护系统的影响,结果表明:较小的液相爆破片爆破压力和爆破片爆破延迟时间、较短的泄放管长度以及液相爆破片放置在下腔室,将更有利于保护系统响应和二回路的完整性。

简单反应、单一反应、复杂反应等术语辨析

本文对简单反应、单一反应、复合反应、复杂反应、对峙反应、平行反应、竞争反应、连串反应、串联反应、多米诺反应、连续反应、正向反应、逆向反应、可逆反应、链[式]反应等容易混淆的化学反应术语进行了辨析,根据全国科学技术名词审定委员会定义等,推荐使用基元反应、总反应、可逆反应、平行反应、连串反应、链反应。

预期眼动任务中反应时呈双峰分布的神经环路模型

在执行精确时间内产生预期眼动的任务时,猕猴的反应时间呈现双峰分布.对这一现象,本文设计了包含大脑皮层的顶内沟外侧区(lateral intraparietal area,LIP)和辅助眼区(supplementary eye fields,SEF)、基底节(basal ganglia,BG)与上丘脑(superior colliculus,SC)在内的并行神经环路模型,通过计算模拟复现出双峰分布.本文探究了该分布的神经机制,发现SEF和LIP神经元群体之间的竞争过程导致了2个峰的出现,并且SEF脑区主要负责预期性眼动,主导了第1个峰的出现,LIP脑区主要负责由视觉刺激引发的反应性眼动,主导了第2个峰的出现.本文进一步地讨论了影响双峰分布形态的关键参数,从计算神经科学的角度探索了时间预期执行的过程.

绝经后骨质疏松症肾阴虚证关联基因CLCF1启动子区相互作用转录因子的筛选及分析

目的检测、分析与CLCF1基因上游启动子区域相互作用的转录因子。方法采用DNA pulldown技术联合质谱鉴定的方法检测与CLCF1基因启动子区域相互作用的蛋白,对鉴定出的蛋白质进行生物信息学分析,筛选出50个转录因子,使用平行反应监测(parallel reaction monitoring,PRM)技术靶向验证转录因子的表达情况。结果试验组与对照组共筛选出251个差异蛋白,GO富集结果表明差异蛋白主要涉及核糖体生物发生、正向调控DNA模板转录等生物学过程,包含转录调节复合物、SWI/SNF超家族型复合物,具有与cAMP应答元件结合、ATP水解活性等分子功能。KEGG通路显示,差异蛋白主要参与人t细胞白血病病毒1型感染、线粒体自噬、甲状腺激素等信号通路。PRM验证发现MAFK、TFE3、MITF、JUNB、FOSL2这5个转录因子表达趋势与DNA pulldown检测结果一致。结论MAFK、TFE3、MITF、JUNB、FOSL2这5个转录因子可能与CLCF1基因启动子区相结合。