航天诱变番茄花粉的红外光谱研究

应用傅里叶红外光谱(FTIR),测试分析了4种番茄花粉样品的一维红外谱和二阶导数谱。结果表明,番茄花粉富含蛋白质、氨基酸和碳水化合物类成分;航天诱变选育番茄花粉的图谱与普通系统选育花粉的图谱基本类似,但在个别峰位处发生了变异。2种航天诱变选育花粉产生的共同变异是CH₃和C—O振动峰增强;不同的是大小番茄航天诱变选育花粉分别在酰胺Ⅰ带和酰胺Ⅱ带处的吸收增加。     

2-烷基TCNQ的红外光谱和结构研究——CH_2剪式振动的双峰与晶体场分裂的关系(英文)

测量了2-烷基TCNQ(C8TCNQ,C12TCNQ,C18TCNQ)浇铸膜的红外光谱,发现这类化合物的红外CH2剪式振动在1 471和1 462 cm-1处显示2个峰。这2个峰的强度比(I1 471/I1 462)随着烷基链的长度增加而明显减少。另外,来自CH2的1 471 cm-1吸收峰与来自TCNQ环的1 529 cm-1吸收峰的相对强度随着碳链的长度增加而不发生变化。CnTCNQ系列化合物的红外光谱CH2的剪式振动行为与长链脂肪酸中CH2行为很不相同。在长链脂肪酸中,晶体场效应导致了剪式振动分裂。考虑C12TCNQ的晶体结构,而将1 471cm-1峰归属为非叉指对接的碳链,将1 462 cm-1峰归于叉指对接的碳链,双峰的出现与晶体场分裂无关。并且得到烷基TCNQ中,非叉指对接的碳链的长度与碳链总长度无关的结论。     

婴幼儿奶粉的FTIR分析与鉴定

采用傅里叶变换红外光谱法(FTIR)获得了六种婴幼儿奶粉的红外光谱及其二阶导数谱. 奶粉中的脂肪(1 747, 2 854, 2 926 cm-1)、蛋白质(1 658, 1 540 cm-1)和糖(1 200～900 cm-1)等主要营养成分具有明显的红外指纹特征. 麦芽糊精、蔗糖和乳糖同样具有明显的指纹特征, 随着添加量的不同而改变. 同一厂家不同类型的婴幼儿奶粉, 脂肪、蛋白质和糖含量差异较大, 红外光谱差异较显著;不同厂家相同类型的婴幼儿奶粉的红外光谱差异较小, 但其二阶导数谱具有明显的指纹特征. 该方法简便、快速、可直观的评价奶粉的品质优劣.     

野生蕈菌孢子的傅里叶变换红外光谱研究

傅里叶变换红外光谱法(FTIR)研究了9种野生蕈菌的孢子,分析了主要吸收峰的归属,结果显示孢子的主要成分为脂类物质、蛋白质和多糖等。在1800—750cm-1光谱范围内,不同属、不同种的野生蕈菌孢子光谱显示了一定的差异,可以用来区分不同种类的孢子。对1800—1500cm-1和1200—1000cm-1范围的二阶导数光谱分别进行相关分析,9种孢子在1800—1500cm-1范围内的相关性相对较好,相关系数在0.843—0.998范围,表明它们含有的主要化学成分脂类物质、蛋白质等比较相似;在1200—1000cm-1范围内相关性较差,相关系数最大为0.780,最小为0.144,表明多糖物质构型或含量具有较大差异。傅里叶变换红外光谱结合特征峰分析和相关分析极有可能用于鉴别蕈菌孢子。     

硼酸三甲酯为探针红外光谱定量研究氧化镁的路易斯碱性

采用硼酸三甲酯(BATE)作为探针分子对MgO的路易斯碱性进行了红外光谱定量研究。MgO对硼酸三甲酯的吸附使硼酸三甲酯在1360cm-1的谱峰分裂成1410cm-1和1300cm-1两个峰,1036cm-1的谱峰紫移到1060cm-1。低压下吸收峰高与硼酸三甲酯压力成正比,与MgO含量成正比。结果表明MgO有一定的路易斯碱强度,与硼酸三甲酯之间的吸附是单分子层化学吸附。     

傅里叶显微红外研究C-末端酸性蛋白对α-硫素原核表达过程的影响

采用傅里叶变换显微红外手段研究了在信号肽缺失的情况下,C-末端酸性蛋白的存在对小麦α-硫素原核表达过程中蛋白质二级结构的影响.SDS-PAGE表明带有酸性蛋白(Sc样品)的重组质粒在大肠杆菌BL21(DE3)中以包涵体形式高效表达;而酸性蛋白缺失(S样品)可以极大提高外源蛋白的可溶性.通过对含有S及Sc的全细胞在诱导前及诱导后2 h的酰胺Ⅰ带区域图谱求筹谱及二阶导数谱,发现诱导前在1 630cm~1处吸收较弱,而在诱导2 h左右,在1 630 cm~(-1)处检测到明显的吸收峰,该位置的吸收主要来自于聚集体的贡献.进一步对酰胺Ⅰ带区域进行傅里叶去卷积处理,结合高斯曲线拟合,发现在Sc样品中随着诱导时间的增加,聚集体含量逐渐增加,这与SDS-PAGE结果一致.此外,伴随着聚集体的形成,α-螺旋的含量逐渐增加;而β-折叠和无规卷曲的含量却逐渐减少.在S样品中观察到无规卷曲的含量随诱导时间的增加逐渐提高,而β-转角及(1 629±1)cm~(-1)处对应的β-折叠的含量却逐渐减少.上述现象表明:C-末端酸性蛋白的引入导致表达过程中β-折叠和无规卷曲逐渐向聚集体和α-螺旋转化.     

红外光谱法用于肉苁蓉属中药鉴别研究

采用傅里叶变换红外光谱(FTIR)及其二阶导数谱和二维相关红外光谱对传统名贵中药材肉苁蓉、管花肉苁蓉和盐生肉苁蓉进行鉴别研究。结果表明,肉苁蓉与管花肉苁蓉的红外谱图有明显区别,相似系数仅0.623 3;而肉苁蓉与盐生肉苁蓉的峰形和峰位均极其相似,相似系数达0.904 8,仅从一维图上无法看出两者的成分差异,但通过二阶导数谱中1 730(1 738),816 cm-1处的峰形差异可发现二者的一些成分含量存在较明显差异。二维相关谱更直观地反映出三者的差异,它们的自动峰个数均不相同。可见,红外光谱法基本可以实现了对肉苁蓉属３种药材的鉴别,而且具有快速、有效和无损等优点。     

二氧化锡气敏纳米粉体的红外光谱研究

采用溶胶-凝胶法制备了纳米级SnO2,利用XRD和IR光谱对其晶化过程进行了详细研究。结果表明,硝酸胶溶有利于SnO2纳米晶的生成,676和545cm-1处的红外吸收分别为二氧化锡中Eu型对称的Sn-O的伸缩振动和A2u型对称的O-Sn-O变角振动,且随着纳米粉体热处理温度的升高,峰形窄化,A2u型的变角振动峰强度降低。     

FTIR同时测定多组分室内有机污染气体的方法研究

随着环保意识的增强,室内空气污染问题越来越引起人们的重视,尤其是挥发性有机化合物(VOCs)的污染。急需建立室内有机污染气体的多组分同时快速检测方法。文章采用红外光谱技术与化学计量学方法相结合,建立了同时测定室内主要有机污染气体苯、甲苯、二甲苯的分析方法。选择红外光谱中3 000～2 600 cm-1,1 100～600 cm-1两个谱段建立分析校正模型,对气体样品中苯、甲苯、二甲苯3种组分的计算浓度与标准浓度之间的复相关系数(r2)分别为0.970,0.955和0.946,校正集的均方根偏差(RMSEC)分别为0.074 2,0.081 9,0.087 7,预测集的均方根偏差(RMSEP)分别为0.132,0.134和0.033 3。 对未知样品的预测结果在误差允许范围内,用该方法同时测定多组分室内有机污染气体是可行的。采用偏最小二乘(PLS)算法所得分析校正模型的各性能指标略优于主成分回归(PCR)算法。     

钛酸铅单晶纳米棒的生长机制和声子特性研究

采用改进熔盐法经一步反应合成了直径50-80nm,长度为1-5μm的单晶PbTiO3纳米棒。纳米棒沿(100)晶向生长,其形成可以用Ostwald成熟机制来解释。PbTiO3纳米棒晶格结构为四方(a=b=3.926,c=3.963),与单晶相比四方性明显下降。通过变温拉曼测试发现其铁电-顺电相变温度为440℃,低于单晶(490℃)。相变过程中“软模”E(1TO)的软化行为(从67 cm-1到56 cm-1)比单晶显著减弱,表明钛酸铅纳米棒中铁电性的弱化。     

皮疹病人血清的表面增强拉曼光谱

研究了皮疹患者和健康人血清的表面增强拉曼光谱。结果表明： 皮疹患者血清中蛋白质主链酰胺Ⅰ的谱线出现在1 648 cm-1处,而在健康人血清中此峰消失。蛋白质侧链C—S键扭曲构象的谱线637 cm-1的相对强度增加了23%,而反式构象的谱线725 cm-1的相对强度减少了60%,说明C—S键的反式构象部分转成扭曲构象,表明皮疹患者血清中蛋白质的有序结构发生变化。类脂物特征峰1 449 cm-1的相对强度增加了近一倍,D-甘露糖的谱线1 099 cm-1消失,表明患者血清中糖蛋白、糖质发生了变化。这些拉曼特征峰为皮疹的诊断以及生化机理研究提供了有力的实验依据。最后用主成分分析(PCA)方法对健康人和皮疹患者血清的表面增强拉曼光谱进行分析,发现皮疹患者血清的主成分分布相对健康人较分散,并且此方法能准确的区分开这２种血清。     

Scanning the energy dissipation process of energetic materials based on excited state relaxation and vibration–vibration coupling

The energy dissipation mechanism of energetic materials(EMs) is very important for keeping safety. We choose nitrobenzene as a model of EM and employ transient absorption(TA) spectroscopy and time-resolved coherent anti-stokes Raman scattering(CARS) to clarify its energy dissipation mechanism. The TA data confirms that the excited nitrobenzene spends about 16 ps finishing the twist intramolecular charge transfer from benzene to nitro group, and dissipates its energy through the rapid vibration relaxation in the initial excited state. And then the dynamics of vibrational modes(VMs) in the ground state of nitrobenzene, which are located at 682 cm~(-1)(v_1), 854 cm~(-1)(v_2), 1006 cm~(-1)(v_3), and 1023 cm~(-1)(v_4),is scanned by CARS. It exhibits that the excess energy of nitrobenzene on the ground state would further dissipate through intramolecular vibrational redistribution based on the vibrational cooling of vi and v_2 modes, v_1 and v_4 modes, and v_3 and v_4 modes. Moreover, the vibration-vibration coupling depends not only on the energy levels of VMs, but also on the spatial position of chemical bonds relative to the VM.     

高压下正戊醇的拉曼光谱原位研究

在室温(23℃)高压条件下,利用立方氧化锆压腔研究了正戊醇在波数800~3 000 cm-1范围内的拉曼光谱。拉曼谱峰随着压力的增大变得越来越尖锐,C—H伸缩振动峰在高压下不易被分离。在0.1 MPa~1.75 GPa,其C—H伸缩振动峰均随着压力的增大向高波数方向线性移动,拉曼频移与压力的线性拟合方程分别为:P(MPa)=69.652 65.(Δνp)single,T=23℃+105.806 93,0(Δpν)single(cm-1)≤23;P(MPa)=77.974 04.(Δpν)2 960,T=23℃+95.390 5,0(Δνp)2 960(cm-1)≤21;P(MPa)=126.956 39.(Δpν)2 863,T=23℃-110.648 09,0(Δpν)2 863(cm-1)≤13。正戊醇的C—H伸缩振动单峰拟合的波数随压力的变化关系为(sνingle/P)T=(14±1)cm-1,适合用来标定体系压力。在压力为1.75 GPa时,正戊醇的拉曼谱峰有明显跳跃,同时镜下观察到其液-固相转变。液-固相转变过程中的摩尔体积变化为ΔVm=1.84×10-6m3.mol-1。     

FTIR光谱法与燕窝的品质分析

直接采用傅里叶变换红外光谱法(FTIR)获得了30种干燕窝产品的红外光谱图.结果显示,这些谱图与天然燕窝的红外光谱图均有不同程度的差异,主要表现在蛋白质、氨基酸(1 634,1 535 cm-1)和多糖(1 034cm-1)等主要营养成分的吸收峰;在干燕窝的谱图中,亚甲基的吸收峰(2 935 cm-1)及蛋白质和氨基酸的吸收峰(1 647,1 533,1 447 cm-1)等处的峰形、峰位和峰强度均与明胶的谱图较相似,说明大多数干燕窝样品中添加了不同量的明胶等物质;有些干冰糖燕窝产品中冰糖含量高达99%,燕窝仅含1%,在红外谱图上几乎观察不到燕窝的特征蜂.因此,市售燕窝的质量令人担忧.用FTIR可简便、快速、直观的评价燕窝产品的品质.     

芳羧酸功能化的聚苯乙烯与Tb(Ⅲ)离子形成的 高分子-稀土配合物的荧光发射性能

通过大分子反应将苯甲酸(BA)键合在聚苯乙烯(PS)侧链, 制得芳羧酸功能化的聚苯乙烯PSBA。以PSBA为大分子配基, 以邻菲啰啉(Phen)为小分子配体, 与Tb(Ⅲ)离子配位, 分别制备了二元配合物PS-(BA)₃-Tb(Ⅲ)与三元配合物PS-(BA)₁-Tb(Ⅲ)-(Phen)₂及PS-(BA)₁-Tb(Ⅲ)-(Phen)₃,采用红外光谱(FTIR)和紫外吸收光谱(UV) 对配合物进行了表征, 深入研究了配合物(溶液与薄膜)的荧光发射性能。 研究结果表明, 大分子配基PSBA与Tb(Ⅲ)离子所形成的二元或三元高分子-稀土配合物均能发射出很强的Tb(Ⅲ)离子特征荧光, 即键合在PSBA侧链的配基BA能有效地敏化Tb(Ⅲ)离子的荧光发射。与二元配合物相比较, 以小分子Phen为第二配体所形成的两种三元配合物具有强度更高的荧光发射。     

铀矿坑水样中铀电沉积层的表征

描述了硫酸铵溶液中铀矿坑水样品中铀的电沉积层特性。 电沉积液为10 ml 0.8 M的硫酸铵溶液, 电流密度0.6 A/cm2, pH值为2.5, 电镀1 h。 电沉积经化学分离后的水样品和电沉积的纯硝酸铀酰样品进行了比较, 并对二者分别做了红外(IR)光谱、 扫描电镜(SEM)、 元素分析以及α能谱测量。 IR谱上铀酰离子的反对称伸缩振动峰在887 cm-1附近, 使电沉积在不锈钢片上的铀主要以铀酰离子水合物的形式存在, 有一部分NH+4以NH3的形式替代水合物中的水, 使电沉积层中铀的化合物形式为UO2(OH)2·xNH3·yH2O或者UO2(OH)2-x·(ONH4)x·yH2O, 铀酰离子通过链的形式形成聚合结构。 SEM照片显示电沉积层均匀, 没堆积成团现象出现。 α谱表明电沉积层中铀的同位素主要是238U和234U, 相应的α能量峰4198和4773 keV很显著, 没其它峰的干扰。 Characteristics of electrodeposited uranium films of uranium ore water sample in ammonium sulphate was investigated in this work. The optimized electrodeposited conditions were as follows: electrolyte was ammonium sulphate of 0.8 M, and current density at the cathode was 0.6 A/cm2, electrolyte pH value was 2.5, the time of plating on the electrodeposition was 1 h. In this situation, the uniform, thin and adheresive films were produced by electrodeposition method. Two samples were made, one electrodeposition of pure uranyl nitrate, and another electrodeposition of uranium ore water sample after chemical separation. Characteristics of electrodeposited uranium films of uranium ore water sample after chemical separation was studied, making comparisons with electrodeposited films of uranyl nitrate. The analysis of film characteristics was done through infrared (IR) spectrum, scanning electron microscopy(SEM), element analysis and α spectrum measurment. According to Fourier transform infrared spectra, the asymmetric stretching vibration band of uranyl group is around 887 cm-1. In addition, according to IR spectrum, we know that uranium exists mainly as the form of hydrated polymeric compound in the film. Electrodeposited uranium films also included many NH+4. Polymeric structures of variable composition were present in the electrodeposited samples, with the unit monomeric formula UO2(OH)2·xNH3·yH2O or UO2(OH)2-x·(ONH4)x·yH2O. Scanning electron microscopy shows that the two samples have similar surface characteristics and no cluster is observed. The samples were also measured by spectrometer equipped with Passivated Implanted Planar Silicon(PIPS) detector. From the α spectrum, we know that isotopes of uranium in the film are 238U and 234U. 235U is not found in the α spectrum. It also shows that the chemical separation process can isolate uranium from other interfering elements effectively, the result of chemical separation is very satisfactory and electrodeposited process is rather efficient. Source electrodeposited in ammonium sulphate through optimized conditions satisfies the need of high resolution α spectrum.     

Two Simple NMR Experiments for Measuring Dipolar Couplings in Asparagine and Glutamine Side Chains

Residual dipolar couplings are now widely used for structure determination of biological macromolecules. Until recently, the main focus has been on measurement of dipolar couplings in the protein main chain. However, with the aim of more complete protein structure, it is also essential to have information on the orientation of protein side chains. In addition, residual dipolar couplings can potentially be employed to study molecular dynamics. In this Communication, two simple NH(2) and spin-state edited experiments are presented for rapid and convenient determination of five residual dipolar couplings from (15)N, (1)H correlation spectrum in asparagine and glutamine side chains. The pulse sequences are demonstrated on two proteins, 30.4-kDa Cel6A in diluted liquid crystal phase and 18-kDa human cardiac troponin C in water.     

IR spectroscopic methods for diagnosis of oncological pathologies in human tissues (Review)

Modern problems in the diagnosis of oncological pathologies using spectroscopic methods of analysis are considered. Fourier-transform IR spectroscopy methods are illustrated by investigation of tissues of breast, thyroid gland, stomach, kidney, lung, and skin excised during surgical intervention. IR spectra of surgical material are compared with data of histological analysis. Spectra of proteins and lipids in malignant neoplasms differ from those in benign tumors and in tissues beyond the pathological focus. Differences in protein spectra are attributed to changes in the supramolecular structure due to cleavage of intramolecular C=OH–N hydrogen bonds. Differences in IR spectra of lipids in neoplasms, when compared with those in normal tissues, are caused by changes in the structure of side chains of fatty-acid radicals appearing in malignant tumors. Spectral signatures of malignant pathology are revealed.     

Structural,electronic,vibrational,and thermodynamic properties of Zr_(1-x)Hf_xCo:A first-principles-based study

The physical properties including structural,electronic,vibrational and thermodynamic properties of Zr1-xHfx Co(x is the concentration of constituent element Hf,and changes from 0 to 1) are investigated in terms of the ABINIT program.The results reveal that all of Zr_(1-x)Hf_x Co have similar physical properties.When Hf concentration x gradually increases from 0.0 to 1.0,the lattice constant decreases from 3.217 ?A to 3.195 ?A very slowly.The calculated density of states(DOS)indicates that the metallic nature is enhanced and the electrical conductivity turns better with the increase of Hf.Moreover,as Hf concentration increases from 0 to 1,the Fermi energy gradually increases from-6.96 e V to-6.21 e V,and the electronic density of states at the Fermi level(N(E_f)) decreases from 2.795 electrons/e V f.u.down to 2.594 electrons/e V f.u.,both of which imply the decrease of chemical stability.The calculated vibrational properties show that the increase of Hf concentration from 0 to 1 causes the maximum vibrational frequency to decrease gradually from about 223 cm~(-1) to 186 cm~(-1),which suggests a lower dispersion gradient and lower phonon group velocities for these modes.Finally,the phonon related thermodynamic properties are obtained and discussed.     

白芥子炒制过程的红外及二维相关光谱研究

采用傅里叶变换红外光谱技术动态跟踪药用植物白芥子的炒制过程,获得了不同炒制时间样本的红外谱,二阶导数谱和热扰动下的二维相关红外谱。白芥子的红外谱表明,白芥子在炒制过程中1 747 cm-1油脂特征蜂的相对强度变化不明显,说明白芥子羧酸酯相对较稳定;而1 657 cm-1附近酰胺Ⅰ带峰和1 546 cm-1附近的酰胺Ⅱ带的吸收峰相对强度显著减小,是因为白芥子在高温炒制过程中,蛋白质(酶)发生了热变性;1 055 cm-1附近的纤维多糖的特征吸收峰在炒制10 min后明显减弱,这与药材表皮纤维多糖加热分解相关联。二阶导数谱和二维相关红外谱的变化规律与红外谱的结果相一致,进一步验证了白芥子药材在炒制过程中发生的主要变化是蛋白质变性及多糖的分解。该方法揭示了药材在炮制过程中所发生的物理化学变化过程,从分子光谱水平上奠定了白芥子药材炮制的目的“杀酶保甙”的理论基础。