Temperature of intermediate mass fragments in simulated ^(40)Ca + ^(40)Ca reactions around the Fermi energies by AMD model

The primary fragments in ^(40)Ca +^(40)Ca reactions at 35,50,80,100,140,and 300 MeV/u were simulated using the antisymmetrized molecular dynamics model,in the phase space at t=300 fm/c with a coalescence radius R_c=5 fm.The standard Gogny interactions g0,g0 as,and gOass were adopted in simulating the collisions at an impact parameter of b=0 fm.It was found,using an isobaric yield ratio method,that temperature of the primary fragment depends on the incident energy and hardness of the interaction potential.The temperature obtained in this work agrees with the results by the self-consistent fitting method.

An improved thermometer for intermediate-mass fragments

An improved thermometer(TIB) is proposed for intermediate-mass fragments via the difference between isobaric yield ratios.The residual free energy of three isobars is replaced by that of the binding energy.The measured fragments in the 140 A MeV ^(40,48) Ca +9Be(181Ta) and^(58,64) Ni +~9Be(^(181)Ta) reactions are analyzed to obtain T_(IB) ranging from 0.6 to 3.5 Me V.TIBis suggested to be a direct determination of temperature avoiding the fitting procedure.

Mass dependence of critical parameter and multiplicity of intermediate mass fragments in heavy ion reaction

The mass dependence of critical parameters for the liquid-gas phase transition and multiplicity of intermediate mass fragment in the heavy ion reaction is qualitatively explored under the framework of lattice gas model.Some results are compared with experimental data.

Emission of Intermediate Mass Fragments as a Function of Impact Parameter for ^(40)Ar+^(nat)Ag Collision at 30 MeV/u

Exclusive intermediate mass fragments（IMFs）are measured at forward angles forthe 40Ar+nalAg reaction at 30 MeV/u.The impact parameter is determined using the totaltransverse momentum method and linear momentum transfer method.IMFs emitted at forwardangles mainly come from projectile fragmentation in peripheral collisions,while IMFs in centralcollision mainly come from decay of hot target-like sources.IMFs from both projectile-like andtarget-like sources are observed in mid-central collision.In addition,the third component,non-equilibrium mid-rapidity components are observed in central,mid-central and peripheralcollisions.

Emission of Intermediate-Mass Fragments From Hot-Nuclei Produced in the Reaction ^(40)Ar+^(nat)Ag at 25 MeV/u

Inclusive Intermediate-Mass Fragments（IMFs）are measured at seven angles for the40Ar+Ag reaction at 25 MeV/u.The energy spectra of IMF from Li to F are obtained.A thermal mod-el with the same parameters well fits the energy spectra of all IMFs at backward angles.These IMFs areevaporated from hot nuclei formed in an incomplete fusion process.The angular distribution and Z distri-bution are calculated with the statistical code GEMINI.

Pairing effects on the fragment mass distribution of Th,U,Pu,and Cm isotopes

In this article,a comprehensive study of the fission process of Th,U,Pu,and Cm isotopes using a Yukawa-folded meanfield plus standard pairing model is presented.The study focused on analyzing the effects of the pairing interaction on the fragment mass distribution and its dependence on nuclear elongation.The significant role of pairing interactions in the fragment mass distributions of^(230)Th,^(234)U,^(240)Pu,and^(246)Cm was demonstrated.Numerical analysis revealed that increasing the pairing interaction strength decreased the asymmetric fragment mass distribution and increased the symmetric distribution.Furthermore,the odd-even mass differences at symmetric and asymmetric fission points were examined,highlighting their sensitivity to changes in the pairing interaction strength.Systematic analysis of the Th,U,Pu,and Cm isotope fragment mass distributions demonstrated the effectiveness of the model in reproducing the experimental data.In addition,the effects of the zero-point energy and half-width parameter on the fragment mass distribution for^(240)Pu were explored.Thus,this study provides valuable insights into the fission process by emphasizing the importance of pairing interactions and their relationship with nuclear elongation.

Crystal Structure and Mass Spectrometric Fragmentation Behavior of Eprosartan

The crystal structure determination and mass spectrometric fragmentation analysis of the medicinal ingredient eprosartan （4-[2-butyl-5-（2-carboxy-3-thiophen-2-yl-propenyl）-imidazol-l-ylmethyl]-benzoic acid） are presented. The single-crystal X-ray diffraction shows that the colorless transparent crystal of eprosartan is of monoclinic system, space group P2/c with a = 16.1861（15）, b = 10.9813（12）, c = 28.610（3） A, β = 118.452（2）°, Z = 4, V= 4471.1（8） A3, Dc = 1.288 g/cm3,μ（MoKα） = 0.178 mm^-1 and F（000） = 1831. The independent part of the unit cell contains two eprosartan molecules and one unordered H2O molecule in the crystal structure which is fixed by inter- and intramolecular hydrogen bonds. The product ions in electrospray ionization tandem mass spectrometry （ESI-MSn） displays the protonated eprosartan dissociated in three competitive pathways and the fragmentation mechanism is proposed and supported by the FTICRMSn results.

Comparative Studies on Mass Spectrometric Fragmentation of Linear Chiral Secondary Alcohols (R)-1-(4-Alkylphenyl) and (R)-1-(4-Alkoxyphenyl/Alkylthiophenyl) Alcohols

Mass spectrometric behaviour of （R） -1- （ 4-alkylphenyl ） alcohols, 1- （4-alkoxylphenyl） alcohols, and 1- （4-alkylthiophenyl） alcohols were studied with the aid of mass-analyzed ion kinetic energy spectrometry under electron impact ionization. All the title compounds show a tendency to eliminate a water molecule to form alkene ions and undergo an a-cleavago to produce protonated aldehyde ions by the loss of alkyl radicals. Except these two common fragment ions, they also show some different fragmentations due to with or without oxy/thioether-linkage.

Specific Mass Spectrometric Fragmentations from the Dissociation of Intermediate Ion-Neutral Complexes

It is reported that two kinds of specific mass spectrometric fragmentations are generated from dissociations of the intermediates of both the ion-neutral complex and the proton-bound complex. Collision-induced dissociation, isotopic labelling, and semi-empirical AM1 calculations were used to investigate the formation mechanism of the ion of m/z 139 from ionized tetrahydroimidazole-substituted methylene beta-diketones and the unimolecular fragmentations pathway of 3-phenyl-1-butyn-3-ol upon electron impact.

Effects of Rock Mass Conditions and Blasting Standard on Fragmentation Size at Limestone Quarries

The size distribution of fragmented rocks depends on not only the blasting standard but also the mechanical properties, joint system and crack density of rock mass. As, especially, the cracks in the rock mass are heavily developed at the limestone quarries in Japan, the joints and/or cracks in the rock mass have big impacts on the blasting effects such as the size of fragmented rocks. Therefore, if the joint system and/or crack density in the rock mass can be known and evaluated in quantity, the blasting operation can be done more effectively, efficiency and safety. However, the guideline for designing the appropriate blasting standard based on the rock mass condition such as mechanical properties, joint system and/or distribution of cracks, discontinuities, from the scientific point of view, has not been developed yet. Therefore, a series of blasting tests had been conducted in different mines and faces, geological conditions and blasting standards in order to know the impacts of each factor on the blasting effects. This paper summarizes the results of blasting tests and describes the impacts of rock mass conditions and blasting standard on the size of fragmented rocks.

Discrimination of Structural Isomers of Aromatic Compounds with EI Mass Spectra and Their Ionization Efficiency Curves of Dehydrogenated Fragment Ions

The mechanism of ionization and fragmentation for terphenyl (diphenylbenzene) with three structural ring isomers (ortho-, meta- and para-), and stilbene (1,2-diphenylethylene) with two geometrical isomers (trans- and cis-) by EI mass spectrometry and ionization efficiency curves are investigation.

UPLC-Q-Orbitrap-MS快速分析水红花子的化学成分

目的建立水红花子化学成分的快速鉴定方法。方法利用超高效液相串联四极杆静电场轨道阱质谱(UPLC-Q-Orbitrap-MS)技术,正、负离子模式下分别采集一级、二级质谱信息。通过推导质谱裂解规律,与质谱数据库(MassBank、mzCloud)、文献数据、对照品比对等方式,对化合物进行指认。结果从水红花子中共鉴定出54种化学成分,主要包括黄酮类、酚酸类、生物碱类等,其中有15种成分为首次从水红花子中发现,也是首次从药用植物红蓼中发现。结论该研究可为水红花子的深入质量评价及药效物质基础研究提供依据。

爆炸成型弹丸侵彻不同材料靶板后效破片特性试验研究

为研究靶板材料性能对爆炸成型弹丸(Explosively Formed Projectile,EFP)侵彻靶后破片特性的影响,开展EFP侵彻不同材料靶板(Q235钢、45号钢、装甲钢、2A12铝)后效破片特性试验,采用X光摄影方法观测靶后破片云形态及膨胀尺寸,通过布置多层纤维板获得破片散布特性,并对靶后破片进行回收。研究结果表明:在靶板密度一定的情况下,靶板强度主要影响破片云轴向膨胀能力,对径向膨胀能力影响很小;靶后破片环形毁伤区的飞散角位于20°~25°范围内差别不大,但是靶板背面出口崩落会造成靶后破片飞散角出现极大值,随着钢靶强度的增大,靶后破片径向散布增强,破片总数减小,但是大质量段钢破片数量增多;不同强度钢靶产生的钢破片平均尺寸满足Kipp等提出的基于材料流动应力的碎片尺寸模型。

基于UPLC-Q-TOF-MS/MS的“略麻1号”茎秆与块茎化学成分分析

目的:对“略麻1号”茎秆与块茎化学成分进行比较研究。方法:采用超高效液相色谱-四极杆飞行时间质谱法(UPLC-Q-TOF-MS/MS),Xbridge BEH C_(18)色谱柱(100 mm×2.1 mm,1.7μm),以0.1%甲酸水溶液-乙腈为流动相进行梯度洗脱,流速为0.3 mL·min^(–1);扫描方式采用正、负离子Full-ddMS2模式下采集数据;结合对照品、相关文献及质谱裂解规律对样品中成分的二级质谱数据进行分析。结果:从“略麻1号”茎秆中共鉴定出153个化合物,包括酚类20个、有机酸类46个、黄酮类11个、氨基酸类12个、生物碱类14个、其他类50个;从“略麻1号”块茎中共鉴定出126个化合物,包括酚类21个、有机酸类36个、氨基酸类13个、生物碱类11个、其他类45个。结论:“略麻1号”茎秆和块茎在物质基础上差异较大,在开发应用中应予以区别,茎秆具有较高的开发应用价值。

飞行时间-高分辨质谱法分析红曲类食品中他汀类物质

采用飞行时间-高分辨质谱法对22批次保健食品和普通食品中他汀类物质进行了分析,并总结了其裂解规律.利用高效液相色谱法测定了保健食品和普通食品中洛伐他汀总含量,内酯型与酸型洛伐他汀的比例.结果表明,保健食品及普通食品D1,D2中他汀类物质含量较高,不同样品中内酯型与酸型洛伐他汀的总含量及比例不同;保健食品中洛伐他汀日服用量在国家规定的安全范围内;大部分普通食品中未检出他汀类物质.

基于GC-Q-Exactive-MS的灵芝孢子油化学成分定性分析

目的:利用高分辨气相色谱-四级杆-静电轨道阱质谱法(GC-Q-Exactive-MS)定性分析灵芝孢子油的化学成分。方法:采用GC-Q-Exactive-MS,在电子轰击(EI)源下获取化合物的全扫描质谱数据,通过总结脂肪酸类、萜类、甾醇类及醛类化学成分的质谱裂解规律,并检索NIST、MassBank、HMDB、PubChem在线数据库及查阅相关文献,对灵芝孢子油的各类化学成分进行鉴定。结果:从灵芝孢子油中共鉴定了22个化学成分,包括3个脂肪酸类、4个萜类、4个甾醇类、4个醛类及7个其他类化合物。结论:研究结果为灵芝孢子油质量控制和中药弱极性化学成分定性分析提供了参考。

微液滴中N,N-二甲基苯胺类化合物的氧化行为研究

小尺寸、高电场的微液滴具有独特的化学性质,可以加速化学反应或实现液相中一些无法进行的反应。本文基于微液滴的化学特点,搭建了微液滴喷雾质谱平台,研究N,N-二甲基苯胺(DMA)类化合物的氧化行为和裂解反应。利用微液滴在空气-水界面自发产生的超高电场,使DMA类化合物发生氧化反应,形成了丰富的、其他手段难以获得的高活性自由基阳离子(DMA^(+·)),发现在整个微液滴反应中,DMA^(+·)占据主导地位,引导其他氧化反应进行。另外,通过改变DMA反应条件,探究实验条件和取代基模式对产生DMA^(+·)丰度和稳定性的影响,结果表明,对位有供电子基团有利于自由基阳离子的稳定。此外,DMA^(+·)解离后主要丢失氢自由基以及进一步发生甲基迁移反应丢失HC≡N,当DMA的对位连有供电子基团时,会促进该迁移反应的发生。该研究有助于加深对水微滴化学促进氧化反应特性的理解,有望将制备的高活性自由基阳离子等活性物种应用于化工或制药等领域。

Rapid chemome profiling of Artemisia capillaris Thunb. using direct infusion-mass spectrometry

Background:As one of the most popular traditional Chinese medicines(TCMs)for the treatment of various liver diseases,virgate wormwood herb(Artemisia capillaris Thunb.)has a long application history in TCM practices.It has been well established that the chemical composition is responsible for the pronounced therapeutic spectrum of A.capillaris.Although they are comprehensive,the time-intensive liquid chromatography coupled to tandem mass spectrometry(LCeMS/MS)assays cannot fully satisfy the analytical measurement workload from many test samples.Direct infusion-MS/MS(DIeMS/MS)may be the optimal choice to achieve high-throughput analysis if the mass spectrometer can universally record MS2 spectra.Methods:According to the application of gas phase ion fractionation concept,the MS/MSALL program enables to gain MS2 spectrum for each nominal m/z value with a data-independent acquisition algorithm via segmenting the entire MS1 ion cohort into sequential ion pieces with 1 Da width,when sufficient measurement time is allowed by DI approach.Here,rapid clarification of the chemical composition was attempted for A.capillaris using DIeMS/MSALL.A.capillaris extract was imported directly into the electrospray ionization interface to obtain the MS/MSALL measurement.After the MS1-MS2 dataset was well organized,we focused on structural characterization through retrieving information from the available databases and literature.Results:Twenty-six compounds were found,including 12 caffeoyl quinic acid derivatives,7 flavonoids,and 7 compounds belonging to other chemical families.Among them,24 ones were structurally identified.Compared with the LCeMS/MS technique,DIeMS/MSALL has the advantages of low-costing,solvent-saving,and time-saving.Conclusions:Chemical profiling of A.capillaris extract was accomplished within 5 min by DIeMS/MSALL,and this technique can be an alternative choice for chemical profile characterization of TCMs due to its extraordinary high-throughput advantage.

A Mass Spectrometric Study of Kratom Compounds by Direct Infusion Electrospray Ionization Triple Quadrupole Mass Spectrometry

Mitragynine (MG) and its major metabolites 7-hydroxymitragynine (7-OH-MG) are two of the major components of the plant extract Kratom, which is a tree planted in Southeast Asia. Kratom has long been used by opioid-dependent individuals as an alternative to their unavailable opioid of choice and chronic pain medication, as a stealth-to-urine drug screening opiate substitute while in opioid recovery treatment and recreationally, alone or as a booster. In this study, a direct infusion method was utilized and electrospray ionization triple quadrupole mass spectrometer was used as the detector for data acquisition. Pharmacokinetic study was conducted to investigate the effect of mitragynine and 7-hydroxymitragynine and major fragments of both compounds were proposed.