Variable low-mass filtering using an electrodynamic ion funnel

An adjustable low-mass filter has been developed for an electrospray ionization (ESI) source to block ions associated with unwanted background species from entering the mass spectrometer. The low-mass filter is made by using an adjustable potential energy barrier from the conductance-limiting plate of an electrodynamic ion funnel, which prohibits species with higher ion mobilities from exiting the ESI source. We show that this arrangement provides a linear voltage adjustment for low-mass filtering from m/z 0 to 500. Mass filtering above m/z 500 is also performed; however, higher-mass species are attenuated. The mass filter was tested with a liquid chromatography/mass spectrometry (LC/MS) analysis of a bovine serum albumin (BSA) tryptic digest and resulted in the ability to block low-mass, background species, which accounted for 40-70% of the total ion current immediately behind the ESI source during peak elution and detection.     

Structural Investigation of Guest-to-Host and Ligand-Ligand Interactions in Werner Clathrates of [Ni(4-Etpy)4(NCS)2]⋅ nG Type (G = Naphthalene Derivatives). The Crystal Structure of [Ni(4-Etpy)4(NCS)2]⋅1-Methylnaphthalene

The stoichiometry and spectral properties of [Ni(4-Etpy)4(NCS)2]nG clathrates have been studied where n = 2 for G = 1-BrN (N = naphthalene), n = 1 or 2 for G = 1-MeN, and n = 0.5 for 2-MeN and 2-BrN. The complexes under study show electronic absorption spectra typical of an octahedral environment of the Ni(II) central atom. The differences found in IR spectra for the (CN) and (Ni–-NNCS) vibrations are discussed. The crystal structure of [Ni(4-Etpy)4(NCS)2]1-MeN was determined by X-ray diffraction and refined to R = 0.0586. Discrete non-centrosymmetric [Ni(4-Etpy)4(NCS)2] molecules form layers of a host structure and the space between the layers is occupied by 1-MeN. The relationship between interatomic distances in the host complex of similar clathrates are discussed.     

基于碘乙酸功能化树枝状聚合物的硫巯化肽段选择性富集新方法

蛋白质的硫巯化是一种重要的氧化翻译后修饰，在细胞衰老、内质网应激、血管舒张、细胞凋亡等过程中扮演重要角色。利用蛋白质组学技术表征硫巯化修饰具有十分重要的意义。该文发展了一种基于碘乙酸功能化的聚酰胺-胺树枝状聚合物（PAMAM-INS），并结合滤膜辅助的样品预处理技术用于硫巯化肽段的富集（简称FADE策略），利用FADE策略能从100倍质量干扰的牛血清白蛋白酶解产物中选择性地富集出硫巯化标准肽段。将细胞培养稳定同位素标记技术引入到FADE策略中，并将其应用于不同浓度梯度硫氢化钠刺激的SHSY5Y细胞硫巯化蛋白质组分析，共鉴定到163条硫巯化肽段。生物信息学的结果表明，硫巯化修饰可能在中枢神经系统中扮演着重要角色。     

小功率空气冷却ICP-AES 研究I——小功率空气冷却ICP的特性

本文用顺序等离子体光谱仪研究了27.12MHz他激式R.F.发生器点燃的小功率空气冷却ICP的特性。测量并比较了二十个元素五十七条谱线在空气冷却和氩冷却两种ICP中的检测限。     

BaF（Cl,Br）：Sm^2＋的光谱烧孔与光激励发光过程

Ｘ射线辐照前后，在ＢａＦ（Ｃｌ，Ｂｒ）：Ｓｍ＾２＋中以５６０ｎｍ的Ｎｄ：ＹＡＧ脉冲光在液氮温度下进行了双光子烧孔实验和光激励发光实验，结果表明，Ｓｍ＾２＋掺杂的碱土金属氟卤化物光谱烧孔过程中伴随着光激励发光过程，这一过程直接影响光谱烧孔过程的进行。     

MEASUREMENTS OF CHAIN INTERPENETRATION OF POLYMER GLASSES

The concept of entanglement provides the basis of our current understanding of the flow behavior of polymer melts, Current techniques developed to investigate the degree of interpenetration of polymer chains only provide indirectly the information of the degree of entanglement in a relatively large scale （several to tens of nanometer）. In this article, we report ^1H-NMR spectroscopy with dipolar filters under fast magic angle spinning for probing chain interpenetration of polymer glasses at the molecular level.     

Fourier transform Raman spectral measurements of powdered quaternary mixtures of organic compounds: Exceptional pure component spectral reconstruction using band-target entropy minimization (BTEM)

Fourier transform Raman spectra of eight mixtures of four organic solids, namely dicyandiamide, melamine, acetamide and urea were measured. Matrices formed from these spectra were first subjected to singular value decomposition to obtain the right singular vectors. The right singular vectors were then subjected to blind source separation using band-target entropy minimization (BTEM), thus no a priori information (i.e. involving the nature of the components present, their spectra, nor their concentrations) was included in the analysis. The recovered pure component spectra are of exceptionally high quality and are consistent with pure reference spectra. Various empirical and statistical tests, such as the Euclidean norm and target transform factor analysis, were employed to assess the quality of the recovered spectra. The present results indicate the applicability of combined Raman and BTEM analysis for solid mixtures.     

Synthesis and Visible Spectral Behaviour of Some New N‐Bridgehead Heterocyclic Cyanine Dyes Incorporating Pyrazolo (4,5‐b) Indolizine (Benzoindolizine)

The new unsymmetrical N‐bridgehead, apo (zeromethine), mono‐methine, dimethine, meso substituted tetramethine and styryl cyanine dyes incorporating pyrazolo (4,5‐b) indolizine (benzoindolizine) nuclei were prepared. Structural confirmation was carried out by elemental analyses, IR, H‐NMR, mass spectra and ¹³C‐NMR with the aid of carbon DEPT spectral data. The visible absorption spectra for the newly synthesized cyanines were examined in 95% ethanol.     

Photophysical studies of some dyes in aqueous solution of triton X-100

The spectral (both absorption and fluorescence) and photoelectrochemical studies of a few selective dyes, namely, anionic erythrosin B, neutral riboflavin and cationic safranin O have been carried out in aqueous solution of triton X-100, a neutral surfactant. The results show that the ionic dyes, erythrosin B and safranin O form 1:1 electron donor-acceptor (EDA) or charge-transfer (CT) complexes with triton X-100 both in the ground and excited states, whereas neutral dye riboflavin in its excited state forms 1:1 complex with triton X-100. In these complexes, the dyes act as electron acceptors whereas triton X-100 acts as an electron donor. The fluorescence spectra of erythrosin B and safranin O in presence of triton X-100 show enhancement of fluorescence intensity with red and blue shifts respectively while riboflavin shows normal quenching of fluorescence. A good correlation has been found among photovoltage generation of the systems consisting of these dyes and triton X-100, spectral shift due to complex formation and thermodynamic properties of these complexes.