低能离子注入固态甲酸钠的质能沉积效应

以N~ 、H~ 、Ar 三种离子分别辐照固态甲酸钠样品，经电子顺磁共振（EPR），红外光谱（IR）的检测。结果发现，三种低能离子辐照后的甲酸钠样品中产生了COO~-自由基和亚甲基（－CH_2）．同时，结合茚三酮反应，证明了辐照后的甲酸钠样品中还含有新的基团──氨基（NH_2），并给出了氨基的产生量与注入离子的剂量和能量的相关曲线．     

110 keV Fe＋离子束对氨基酸衍生物的辐射分解

用200 kV离子注入机提供的110 keV Fe＋离子束注入L(＋)-半胱氨酸盐酸盐单晶水合物薄膜样品,离子注量为2.5×1016 ions•cm－2.离子注入后刮下薄膜进行简单固态混和,在傅里叶变换红外光谱仪、高效液相色谱仪和电喷雾电离-傅里叶变换质谱仪上对离子注入前后的样品分别进行了测试.对离子注入样品的两次红外光谱分析结果有所不同,表明薄膜样品不同部位受低能铁离子束辐照后可发生不同的辐射分解,但二者又具有一定的相似性,都反映了原分子中氨基、羧基和巯基等基团的受损和新的硝基的生成.高效液相色谱和傅里叶变换质谱分析表明,离子注入样品中产生了多种不同分子量的新分子,证实110 keV Fe＋离子束能够引起氨基酸衍生物的辐射分解.     

几种螯合剂解镍致小鼠急性肾毒性作用比较

为寻找镍(Ni)新型解毒剂，小鼠腹腔注射氯化镍溶液(5 mg Ni/kg)，观察二乙氨基二硫代甲酸钠(DDTC)，二羟乙氨基二硫代甲酸钠(DHED)，N-苯甲基-D-葡糖氨基二硫代甲酸钠(BGD)，meso-2，3-二巯基丁二酸钠(DMSA)及环己烷二胺四乙酸钠(CDTA)等螯合剂对镍致小鼠肾脏毒性的解毒作用。镍染毒引起小鼠肾脏脂质过氧化(LPO)和钙、铁及锌浓度增加，血清肌酐及血液尿素氮(BUN)升高。镍染毒30分钟和24小时后进行各螯合剂治疗(剂量均为400 μmol/kg     

低能氮离子对苯甲酸钠溶液的化学改性

利用气体尖端放电产生低能氮离子,这些离子在放电间隙的电场加速下攻击苯甲酸钠(PhCOONa)水溶液,造成溶液中分子的损伤。氮离子的作用使溶液的紫外吸收发生显著的变化,与茚三酮呈正反应,表明进入溶液的氮元素形成了某种形式的氨基。红外吸收光谱的分析进一步表明低能氮离子与PhCOONa溶液作用形成了酰胺及亚硝基化合物。所有的实验结果都反映了低能离子通过损伤分子及进一步与损伤碎片化学合成的化学改性作用。     

碱基在十二胺-N,N-二亚甲基膦酸改性氧化锆固定相上色谱行为的研究

研究了碱基在十二胺-N,N-二亚甲基膦酸(DDPA)改性氧化锆固定相（DPZ）上的色谱保留行为,考察了流动相中甲醇含量、流动相pH值、缓冲溶液中离子类型和离子强度对碱基保留的影响,对DDPA在氧化锆表面的吸附方式进行了研究。研究结果表明,DDPA仅以一个膦酸基与氧化锆结合,因而DPZ固定相表面上除了有长链的疏水烷基外,还有酸性的膦酸基和碱性的氨基。碱基分子中也存在氨基和酰胺基等极性基团,因此碱基在DPZ固定相上除了有疏水作用外,还具有电荷排斥作用、离子交换作用等多种保留机理。由于多种保留机理的存在,使得碱基在DPZ固定相上具有较好的分离选择性,在酸性条件下对碱基混合样品的分离取得了满意的结果。     

一种由多氟碘代烷合成多氟羧酸的新方法

本文报道了一种新的合成多氟羧酸的方法:即在银(I)离子存在下,甲酸钠与多氟烷基碘代烷反应的结果。     

298.1 K时脂肪酸钠盐对定组成水溶液中非水组分活度系数的影响

本文报告了298.1 K下甲酸钠(C_1), 乙酸钠(C_2)、丙酸钠(C_3)、丁酸钠(C_4)、戊酸钠(C_5)、已酸钠(C_6)和庚酸钠(C_7)七个盐对水溶液中乙醇、丙酮和乙腈三个溶质的活度系数的影响。实验方法是, 固定水溶液中乙醇、丙酮和乙腈的浓度(摩尔分数约为0.05), 用气相色谱法检测不同盐浓度下平衡气相中溶质分压的变化, 从而得出溶质的盐效应活度系数γ。本文给出了一个可以连续取样的气液平衡装置的设计。由实验结果可见, 不同碳链大小的脂肪酸根离子的盐效应作用差别很大。C_1、C_2的盐效应主要由于静电作用; 对C_3、C_4盐, 除静电作用外,它们的疏水基与溶质疏水基的相互作用对盐效应有显著影响; C_5、C_6和C_7的盐效应则反映了疏水离子的特色, 疏水水化、疏水相互作用、疏水离子形成的聚集体与不同官能团的特定相互作用等几项因素, 导致儿个溶质盐效应的差异。     

几种螯合剂解镍致小鼠胰脏毒作用比较

小鼠腹腔注射氯化镍溶液(5 mg Ni/kg)染毒，观察了N-苯甲基-D-葡糖氨基二硫代甲酸钠(BGD)、二乙氨基二硫代甲酸钠(DDTC)、二羟乙氨基二硫代甲酸钠(DHED)及meso-2，3-二巯基丁二酸钠(DMSA)等螯合剂对镍致小鼠胰脏毒性的解毒作用。镍染毒后引起小鼠胰脏胰蛋白酶活性升高和羧肽酶A活性降低以及组织中镍、钙、锌浓度增加；镍染毒30 min和24 h后进行各螯合剂治疗(剂量均为400 μmol/kg)，BGD、DDTC和DMSA可明显抑制上述变化，其中BGD解镍毒效果最好、自身毒性最小、对镍致小鼠胰脏毒性有更好的解毒作用。     

预辐射接枝四氟乙烯-乙烯共聚物湿敏膜的制备及特性研究

利用2 MeV电子加速器, 在常温下采用预辐照引发接枝的方法, 在四氟乙烯-乙烯共聚物(ETFE)上接枝丙烯酸(AA)和对苯乙烯磺酸钠(SSS), 制备了一种含羧酸基团和磺酸基团的接枝膜. 傅里叶变换红外光谱(FTIR)分析结果证明了磺酸基团和羧酸基团的成功引入, 并对接枝膜的热力学和化学特性进行了研究. 结果表明, 随着接枝率的增加, 接枝膜的结晶度逐渐降低, 接触角逐渐减小, 接枝膜的亲水性逐渐增强. 利用制备的接枝膜构建了电阻型湿度传感器, 并测定了传感器的电学特性. 在相对湿度(RH)从5%变化到98%时, 传感器电阻线性变化范围接近4个数量级, 具有响应速度快(吸附<1 min, 解吸<2 min), 湿滞小(<2%RH)的特点.     

低能氮离子注入乙醇重水溶液的GC-MS分析

将氮气常压弧光放电产生的N⁺在放电间隙电场的加速下“注入”到乙醇的重水溶液中,利用气相色谱-质谱(GC-MS)分析样品,证实有氘代产物(DCH₂CH₂OH)和羟基取代产物(DOCH₂CH₂OH)生成,这表明低能N⁺诱发水溶液中的反应与水分子分解产生的自由基有关.同时,产物中还检测到乙酸(CH₃COOD )和氨基乙醇(HOCH₂CH₂ND₂),说明反应是在氧化性氛围中进行的,而这种氧化作用可能亦与水分子分解产生的氢氧根自由基有关.氨基乙醇则可能是氮离子俘获重水中的氘形成氨基继而与乙醇反应生成的,这也是氮“沉积”在溶液中的重要形式.这些结果对初步揭示低能离子与水溶液体系反应的机理具有一定的意义.     

Mobile phase variations in thermospray liquid chromatography-mass spectrometry of pesticides

The effect of four different mobile phase compositions with reversed-phase methanol-water (50:50) + 0.05 M ammonium acetate, methanol-water (50:50) + 0.05 M ammonium formate, acetonitrile-water (50:50) + 0.05 M ammonium acetate and acetonitrile-water (50:50) + 0.05 M ammonium formate were compared in filament-on thermospray liquid chromatography-mass spectrometry for the determination of carbamate and chlorotriazine pesticides. In the positive-ion mode, [M + H]+ and [M + NH4]+ were generally the base peaks for the chlorotriazines and the carbamates, respectively. Depending on the mobile phase used, other adduct ions obtained corresponded to [M + CH3CN + H]+, [M + CH3OH + NH4]+, [M + CH3COONH4 + NH4 - 2H2O]+, [M + CH3CN + NH4]+, [M + CH3COONH4 + H - H2O]+ and the dimer [2M + H]+. In the negative-ion mode, [M - H]- and adducts with the ionizing additive [M + CH3COO]- or [M + HCOO]- were obtained. Other ions for the carbamates carbaryl and oxamyl corresponded to [M - CONHCH3 + CH3COOH]- and [M - CON(CH3)2 + HCOO]-, respectively. The variation of mobile phase composition provides additional structural information in thermospray liquid chromatography-mass spectrometry with no appreciable loss of sensitivity. Applications are reported for the determination of carbamate and chlorotriazine pesticides at the ng/g level in spiked and real soil samples, respectively.     

What ion is generated when ionizing acetonitrile?

It has long been assumed that ionizing neutral acetonitrile produces ions with the same atomic connectivity, CH(3)CN(+*). Recent calculations on the C(2)H(3)N(+*) potential energy surface have suggested that it may be difficult to generate pure CH(3)CN(+*) when ionizing acetonitrile. We have probed the interconversion of CH(3)CN(+*) and its lower energy isomer CH(2)CNH(+*) by calculation, collision-induced dissociation mass spectrometry and ion-molecule reaction. The latter ion, ionized ketenimine, is co-generated upon electron or chemical ionization of neutral acetonitrile in the ion source of a mass spectrometer. An estimate of the ratio of the two isomers can be obtained from their respective ion-molecule reactions with CO(2) or COS. CH(3)CN(+*) reacts by proton-transfer with CO(2) and charge transfer with COS, whereas CH(2)CNH(+*) is unreactive.     

低能氮离子诱发氨基酸前生物合成反应的初步研究

利用氮气火花放电产生离子 ,其中的正离子在阴极位降的加速下“注入”到三种羧酸盐的水溶液中 ,诱发其中的化学反应并沉积在水溶液中 .利用高效液相色谱 (HPLC)对离子注入后的样品进行分析 ,结果表明 ,氮离子注入可使氮沉积在溶液中 ,生成氨及氨基酸 ,这一结果不仅验证了低能离子注入样品时的“质量沉积”效应 ,而且还是原始地球条件下氨基酸生成的一种可能的途径     

A novel alpha-helix-liked metallohelicate series and their structural adjustments for the isomorphous substitution

A novel metallohelical motif is well designed and synthesized by mimicking the alpha-helical fold structure of protein. The 1D helical structures of [Cd(CH2(COO)2)(SC(NH2)2)2]n (I) and [Zn(CH2(COO)2) (SC(NH2)2)2]n (II) are primarily induced and stabilized by the multiple long-range intrahelix hydrogen bonds. Malonate dianion acts as a bidentate ligand coordinated with metal ions to form the backbone of the helix, and thiourea molecules that bend into the helical turn are involved in the intrahelix hydrogen-bond system. The metal ion occupations in the helix of I and II can be freely substituted by simply controlling the initial ratio of those two metal ions. Single crystals of three mixed metal ion complexes of [Cd0.77Zn0.23(CH2(COO)2)(SC(NH2)2)2]n (III), [Cd0.50Zn0.50(CH2(COO)2)(SC(NH2)2)2]n (IV), and [Cd0.21Zn0.79(CH2(COO)2)(SC(NH2)2)2]n (V) were synthesized from systems with an initial Cd/Zn mole ratio of 1:1 for III, 1:2 for IV, and 1:8 for V. They are isomorphous as confirmed by X-ray characterization. When the metal ion is substituted, the multiple intrahelix hydrogen interaction motifs of the coordination polymer structure are self-adjusted to sustain their 1D helical motifs.     

Dissociative electron attachment to gas phase glycine: exploring the decomposition pathways by mass separation of isobaric fragment anions

Dissociative electron attachment to gas phase glycine generates a number of fragment ions, among them ions observed at the mass numbers 15, 16 and 26 amu. From stoichiometry they can be assigned to the chemically rather different species NH(-)/CH(3)(-)(15 amu), O(-)/NH(2)(-)(16 amu) and CN(-)/C(2)H(2)(-)(26 amu). Here we use a high resolution double focusing two sector mass spectrometer to separate these isobaric ions. It is thereby possible to unravel the decomposition reactions of the different transient negative ions formed upon resonant electron attachment to neutral glycine in the energy range 0-15 eV. We find that within the isobaric ion pairs, the individual components generally arise from resonances located at substantial different energies. The corresponding unimolecular decompositions involve complex reaction sequences including multiple bond cleavages and substantial rearrangement in the precursor ion. To support the interpretation and assignments we also use (13)C labelling of glycine at the carboxylic group.     

Mass spectral characterization of tetracyclines by electrospray ionization,H/D exchange,and multiple stage mass spectrometry

Electrospray ionization (ESI) and collisionally induced dissociation (CID) mass spectra were obtained for five tetracyclines and the corresponding compounds in which the labile hydrogens were replaced by deuterium by either gas phase or liquid phase exchange. The number of labile hydrogens, x, could easily be determined from a comparison of ESI spectra obtained with N2 and with ND3 as the nebulizer gas. CID mass spectra were obtained for [M + H]+ and [M - H]- ions and the exchanged analogs, [M(Dx) + D]+ and [M(Dx) - D]- , and produced by ESI using a Sciex API-III(plus) and a Finnigan LCQ ion trap mass spectrometer. Compositions of product ions and mechanisms of decomposition were determined by comparison of the MS(N) spectra of the un-deuterated and deuterated species. Protonated tetracyclines dissociate initially by loss of H2O (D2O) and NH3 (ND3) if there is a tertiary OH at C-6. The loss of H2O (D2O) is the lower energy process. Tetracyclines without the tertiary OH at C-6 lose only NH3 (ND3) initially. MSN experiments showed easily understandable losses of HDO, HN(CH3)2, CH3 - N=CH2, and CO from fragment ions. The major fragment ions do not come from cleavage reactions of the species protonated at the most basic site. Deprotonated tetracyclines had similar CID spectra, with less fragmentation than those observed for the protonated tetracyclines. The lowest energy decomposition paths for the deprotonated tetracyclines are the competitive loss of NH3 (ND3) or HNCO (DNCO). Product ions appear to be formed by charge remote decompositions of species de-protonated at the C-10 phenol.     

Threshold collision-induced dissociation of hydrogen-bonded dimers of carboxylic acids

Energy-resolved competitive collision-induced dissociation is used to investigate the proton-bound heterodimer anions of a series of carboxylic acids (formic, acetic, and benzoic acid) and nitrous acid with their conjugate bases. The dissociation reactions of the complexes [CH3COO.H.OOCH]-, [CH3COO.H.ONO]-, [HCOO.H. ONO]-, [C6H5COO.H.OOCH]-, and [C6H5COO.H.ONO]- are investigated using a guided ion beam tandem mass spectrometer. Cross sections of the two dissociation channels are measured as a function of the collision energy between the complex ions and xenon target gas. Apparent relative gas-phase acidities are found by modeling the cross sections near the dissociation thresholds using statistical rate theory. Internal inconsistencies are found in the resulting relative acidities. These deviations apparently result from the formation of higher-energy conformers of the acids within the complex ions induced by double hydrogen bonding, which impedes the kinetics of dissociation to ground-state product acid conformations.     

Endgroup-assisted siloxane bond cleavage in the gas phase

Unimolecular dissociation of H(2)N(CH(2))(3)SiOSi(CH(2))(3)NH(3)(+) generates SiC(5)H(16)NO(+) and SiC(5)H(14)N(+). The formation of SiC(5)H(16)NO(+) involves dissociation of a Si[bond]O bond and formation of an O[bond]H bond through rearrangement. The fragmentation mechanism was investigated utilizing ab initio calculations and Fourier transform ion cyclotron resonance (FTICR) mass spectrometry in combination with hydrogen/deuterium (H/D) exchange reactions. Sustained off-resonance irradiation collision-induced dissociation (SORI-CID) studies of the fully deuterated ion D(2)N(CH(2))(3)SiOSi(CH(2))(3)ND(3)(+) provided convincing evidence for a backbiting mechanism which involves hydrogen transfer from the terminal amine group to the oxygen to form a silanol-containing species. Theoretical calculations indicated decomposition of H(2)N(CH(2))(3)SiOSi(CH(2))(3)NH(3)(+) through a backbiting mechanism is the lowest energy decomposition channel, compared with other alternative routes. Two mechanisms were proposed for the fragmentation process which leads to the siloxane bond cleavage and the SORI-CID results of partially deuterated precursor ions suggest both mechanisms should be operative. Rearrangement to yield a silanol-containing product ion requires end groups possessing a labile hydrogen atom. Decomposition of disiloxane ions with end groups lacking labile hydrogen atoms yielded product ions from direct bond cleavages.     

Crystal Structure of catena-[(Tetrakis-μ2-acetato-μ2-4,4'-bipyridine) dicopper(Ⅱ)] Acetonitrile Solvate

The title compound,[Cu2(CH3COO)4(C8H10N2)]n·nCH3CN1 (C8H10N2,4,4'-bipy = 4,4'-bipyridine),has been solvothermally synthesized in CH3CN and characterized by X-ray diffraction.The crystal is of monoclinic,space group Cc with a = 22.626(6),b = 14.012(4),c =15.106(4) (A),β = 107.610(3)°,V = 4565(2) (A)3,C20H23Cu2N3O8,Mr = 560.49,Z = 8,Dc = 1.631 g/cm3,μ = 1.914 mm-1,Flack parameter = 0.48(1),F(000) = 2288,R = 0.042 and wR = 0.)98 for 8887 observed reflections (I ＞ 2σ(I)).It consists of nearly linear one-dimensional chains [Cu2(CH3COO)4(C8H10N2)]n derived from paddle-wheel [Cu2(CH3COO)4] unit linked by 4,4'-bipy,and CH3CN as guest molecule regularly decorates between the chains.