Specific detection of Lewis x-carbohydrates in biological samples using liquid chromatography/multiple-stage tandem mass spectrometry

The Lewis x structure [Lex, Galbeta1-4(Fucalpha1-3)GlcNAc] motif is one of the tumor antigens and plays an important role in oncogenesis, development, cellular differentiation and adhesion. The detection of Lex-carbohydrates and their structural analysis are necessary to clarify the role of Lex in several biological events. Mass spectrometry has been preferably used for the structural analysis of carbohydrates. Especially, collision-induced dissociation (CID) tandem mass spectrometry (MS/MS), which causes a glycosidic bond cleavage, is used for carbohydrate sequencing. However, Lex cannot be identified by MS/MS due to the existence of the positional isomers, such as Lewis a [Galbeta1-3(alpha1-4Fuc)GlcNAc]. In the present study, we demonstrate the specific detection of Lex-carbohydrates in a biological sample by using multiple-stage MS/MS (MSn). Using pyridylaminated oligosaccharides bearing Lex, we found that the Lex-motif yields a cross-ring fragment by the cleavage of a bond between C-3 and C-4 of GlcNAc in Gal(Fuc)GlcNAc. The Lex-specific cross-ring fragment ion at m/z 259 was effectively detected by sequential scans, consisting of a full MS1 scan, data-dependent CID MS2 scan, MS3 of [Gal(Fuc)GlcNAc+Na]+ at m/z 534, and MS4 of [GalGlcNAc+Na]+ at m/z 388. The sequential scan was applied to N-linked oligosaccharide profiling using a LC/ESI-MSn system equipped with a graphitized carbon column. We successfully detected the Lex-motif and elucidated the structures of several Lex and Lewis y [(Fucalpha1-2)Galbeta1-4(Fucalpha1-3)GlcNAc] oligosaccharides in the murine kidney used as a model tissue. Our method is expected to be a powerful tool for the specific detection of the Lex-motif, and structural elucidation of Lex-carbohydrates in biological samples.     

Micro‐FT‐IR study of stretching a single filament: Polymorphic transition in nylon 6

The polymorphic transition (γ → α conversion) in a single nylon 6 filament under stretching has been explored for the first time by using micro‐FT‐IR spectroscopy. The content of γ‐form deceases with straining while the amount of α‐form gradually increases, suggesting γ → α conversion. A two‐step mechanism, that is, melting and recrystallization, seems pertinent for the γ → α conversion considering that the γ‐form shows somewhat reversible and the α‐form keeps nearly intact upon unloading. Moreover, stress‐induced γ → α conversion at large strain can be well correlated with the molecular orientation in the amorphous phase and thus a serial arrangement between the γ crystals and amorphous phase along the stretching direction is proposed. © 2009 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 47: 898–902, 2009     

Hydrothermal Synthesis and Structure of[{Mo_8V_4O_(36)(VO_4)(VO)_2}n]~(7n-)Bi-capped α-Keggin Fragments Linked to a Chain

The title compound, (H2en)3H3O{Mo8V4O36(VO4) (VO)2} ?4H2O, was hydrothermally synthesized and structurally characterized by means of IR, ESR spectrum and single crystal X-ray diffraction. It crystallized in a monoclinic system with space group P21/c, a=1. 980 4(4) nm, 6=2. 063 4(4) nm, c=l. 192 0(2) nm, =94. 76(3)?and deep black colour. The compound contains V-centered bi-capped a-Keggin fragments {Mo8V7O42} that are linked together by edge-shared units V O5 via V桹梀 bonds, forming a chain.     

硅多晶质量检测分析中的磷检电阻率曲线研究

本文对几种典型的实测电阻率曲线进行分析,利用普凡公式和补偿后净载流子导电模型对曲线的异常进行了合理解释并用低温红外检测结果进行了对比验证.采用硼磷杂质浓度补偿净值方法计算出的数据接近实测情况,电阻率特性曲线符合普凡公式描述的规律,可作为理论特性曲线使用.     

有机磷类阻燃剂的合成及应用进展

由于有机磷阻燃剂具有高效、低毒、无污染及无烟等特点,该领域的研究在国内外得到极大的关注,已经在合成和应用等方面取得了显著成就。 本文对磷系阻燃剂的阻燃机理及近年来磷系阻燃剂的应用进展作了简要综述。 分别综述了各类有机含磷阻燃剂的研究进展,并提出了有机磷阻燃剂今后的发展方向。     

Lasso算法的油砂钠元素近红外建模

以油砂中钠元素为研究对象,首次应用近红外光谱,结合Lasso(least absolute shrinkage and selection operator)建模方法,建立了油砂金属钠含量的近红外光谱定量校正模型,并与传统的PLS建模方法进行比较。结果表明,两种方法建立的油砂金属钠含量校正模型都具有很高的精度,预测性能方面略有差异。在实验验证集与预测集中,PLS与Lasso算法的相关系数分别是：R_v=0.878 8,R_p=0.857 9和R_v=0.887 4,R_p=0.860 0。实验验证了使用近红外光谱快速测定油砂金属钠含量的有效性,并分析了PLS与Lasso算法的适用范围。     

CCD扫描检测光束准直度

提出一种检测光束准直度的新方法。在对波面矢高进行定义的基础上,提出CCD轴向扫描检测激光束准直度的方法。利用采样光波在会聚透镜后形成的衍射图样,测量两个相同基准衍射图样之间的距离,即可确定入射光波的波面矢高,进而确定入射光波的准直度。在给出测量原理及模拟基准衍射图样的基础上．进行了实验验证。CCD轴向扫描方法具有结构简单、加工便利、操作方便的特点,是检测光束准直度的有效方法。     

介质阻挡放电低温等离子体脱硝性能研究

进行了介质阻挡放电低温等离子体脱除伴有SO₂的烟气中NO的研究,分别进行了直接等离子体脱硫脱硝和间接等离子体脱硫脱硝实验。在直接等离子体脱硫脱硝中,模拟烟气等混合气直接通入等离子体发生器,在反应器中电离分解NO以及和生成的高能电子、离子和自由基等离子体相互反应而进行脱除NO;间接等离子体脱硫脱硝中,模拟烟气连接在等离子体发生器出口与从反应器中产生出的等离子体发生氧化反应而进行脱除NO。结果表明,无论直接形式还是间接形式,脱硝效率都要比脱硫效率高,间接脱硫脱硝能够大大降低功率输入,节省能耗,具有重要的实际应用价值和意义。氨气的加入,有利于脱除效率的提升。     

Pressure-induced disordering and phase transformations in Eu2Zr2O7 pyrochlore

ABSTRACT

The structural properties of pyrochlore Eu₂Zr₂O₇ under high pressure have been studied by using Raman spectroscopy and in situ angle-dispersive X-ray diffraction (ADXRD). The results of Raman spectra indicate that Eu₂Zr₂O₇ undergoes a reversible structural change around 21.2?GPa. The results of Rietveld refinements from in situ ADXRD data indicate that the ordered pyrochlore structure (Fd-3m) transforms to the defect-cotunnite structure (Pnma) at 26.5?GPa. The phase transition is irreversible and the transformation process is mainly induced by the accumulations of anti-site defects of the cation sublattice and Frenkel defects on the anion sublattice. Besides, the <Zr–O> bonds should play a more important role than the <Eu–O> bonds in the process of the phase transformation.     

近红外全局隐含温度补偿模型的预测精度分析

温度波动影响含氢基团之间的作用力,从而影响近红外光谱的吸收强度和波峰位置等,导致近红外测量精度的降低。针对温度变化对近红外光谱建模精度的影响,对全局隐含温度补偿方法进行了研究,并对其预测精度进行了分析,分别从预测方差和置信区间两个方面对此类模型的精度进行了理论探讨和验证。同时通过温度的连续变化实验,即在温度连续变化的过程中,等时间间隔采集各样品的近红外光谱,研究了温度变化对光谱主元的连续模式影响,探讨了温度变化影响模型预测精度的方式和途径。最后对某高分子聚合物的粘度测量问题进行了实验验证和误差分析,得到标准温度下所建未经温度补偿的模型和全局隐含温度补偿模型的建模精度分别为：RMSEC=0.243 0, R_c=0.871 6, RMSEP=0.243 2, R_p=0.869 3; RMSEC=0.258 2, R_c=0.870 6, RMSEP=0.265 2, R_p=0.856 0,而当温度变化时,二者预测最大置信区间分别约为1.8和0.9 kPa·s。虽然全局隐含温度补偿模型相比于标准温度模型建模精度略降低,但预测精度提高了一倍左右。理论分析和实验结果均表明,全局温度补偿模型具有较高的预测精度,且对温度的变化有较强的鲁棒性和可靠性。