Conformational energies of silacyclohexanes C5H10SiHMe,C5H10SiH(CF3) and C5H10SiCl(SiCl3) from variable temperature Raman spectra

From variable temperature vibrational Raman spectra, the axial/equatorial enthalpy differences for the substituted silacyclohexanes C₅H₁₀SiHMe, C₅H₁₀SiH(CF₃) and C₅H₁₀SiCl(SiCl₃) were determined. The pure liquids and solutions in various solvents were investigated. Preferred conformations are equatorial for methylsilacyclohexane and axial for trifluoromethylsilacyclohexane, consistent with earlier results from nuclear magnetic resonance experiments and ab initio calculations. For C₅H₁₀SiCl(SiCl₃) an enthalpy difference close to zero was found, which is supported by high‐level which is supported by high‐level quantum chemical calculations at the second‐order Møller‐Plesset (MP2) and coupled cluster with single, double, and perturbative triple excitations (CCSD(T)) levels, which employed various basis sets. A novel synthesis for C₅H₁₀SiCl(SiCl₃) was developed using ClMg(CH₂)₅MgCl instead of BrMg(CH₂)₅MgBr as a starting material. The procedure avoids the formation of partially brominated products, facilitating the purification of the compound. ¹H, ¹³C and ²⁹Si nuclear magnetic resonance data are reported. Copyright © 2012 John Wiley & Sons, Ltd.     

SO(10) v ×SO(10) H grand unified-extended technicolour models

We discuss a recently proposedSO(10) _v ×SO(10) _H grand unified-extended technicolour model. Because proton decay is probably too fast in this model, we study the other possible models based onSO(10) _v ×SO(10) _H . As a result of this analysis only a few of these models could possibly be realistic, they would be slight modifications of that previously proposed. None of them predicts the expected value forΛ _TC, it must be adjusted by introducing another mass scale. In these models ordinary fermion masses tend to be too small.     

液态水、苯和壬基乳化剂混合物冲击压缩特性的实验研究

 利用二级轻气炮在3.75~57.87 GPa 压力范围内,对体积比为10∶10∶1的液态水-苯-壬基酚聚氧乙烯醚混合体系进行了动高压加载实验,获得了10个Hugoniot数据。拟合结果表明,该混合体系的D-u关系可近似用直线方程D=1.407+1.503u_p描述,拟合精度约为0.102。混合体系H₂O-C₆H₆-C₃₅H₆₄O₁₁的冲击压缩实验结果基本符合体积相加原理,而在给定的实验压力区间内,冲击绝热曲线发生多次拐折的事实意味着该系统可能在6 GPa、10 GPa和30 GPa压力点附近发生了多次结构性相变。另外,还讨论了Lawrence-Berthlot混合规则中修正因子对高密度条件下指数-6型相互作用势排斥部分的影响。     

Stern-Volmer quenching and binding constants of 10-alkyl-9(10H)-acridone probes in SDS and BSA

Lucigenin (bis-N-methylacridinium nitrate) is an acridine-based probe that has been extensively used to detect reactive oxygen species (ROs) and has been shown to generate chemiluminescence in many biological materials. N-methylacridone is known to be the main emitter of the lucigenin's chemiluminescent system. This work investigates the distribution of synthesized 10-alkyl-9(10H)-acridone (-methyl, -butyl and -decyl) probes and quenchers (Cu²⁺, MV²⁺, BeV²⁺, Propy⁺ and DoPy⁺ ) in anionic micellar solution of sodium dodecyl sulfate (SDS).The binding ability of 10-alkyl-9(10H)-acridone to a serum lipoprotein (BSA)was investigated.     

二甲基硅硼烷,o-(SiMe)_2B_(10)H_(10),振动光谱的理论研究

本文利用高斯 94从头计算程序在 6- 31 G基组下对二甲基硅硼烷 ,o- (Si Me) 2 B1 0 H1 0 ,进行几何优化及振动光谱的理论计算 ,并对主要谱带特性进行指认 ,结果与实验基本符合。振动模式分析表明 450 cm-1 以下的两个强带中 32 6cm-1 (计算值为 369cm-1 )似乎是两个 Si原子相对笼骨架中其余 B原子整体的伸缩振动 ,而 399cm-1 (计算值为 42 1 cm-1 )则为 Si- Si(及其联带的 C原子一起参与的 )对称伸缩振动。优化几何及振动光谱的研究表明重的杂原子硅占据二十面体硼笼骨架位置后使笼结构的刚性弱化     

Nearly 10-fold enhancements in intermolecular H double-quantum NMR experiments by nuclear hyperpolarization

Intermolecular Multiple-Quantum Coherences (iMQCs) can yield interesting NMR information of high potential usefulness in spectroscopy and imaging – provided their associated sensitivity limitations can be overcome. A recent study demonstrated that ex situ dynamic nuclear polarization (DNP) could assist in overcoming sensitivity problems for iMQC-based experiments on ¹³C nuclei. In the present work we show that a similar approach is possible when targeting the protons of a hyperpolarized solvent. It was found that although the DNP procedure enhances single-quantum ¹H signals by about 600, which is significantly less than in optimized low-γ liquid-state counterparts, the non-linear dependence of iMQC-derived signals on polarization can yield very large enhancements approaching 10⁶. Cleary no practical amount of data averaging can match this kind of sensitivity gains. The fact that DNP endows iMQC-based ¹H NMR spectra with a sensitivity that amply exceeds that of their thermally polarized single-quantum counterpart, is confirmed in a number of simple single-scan 2D imaging experiments.     

Simulation of the thermal decomposition of the C9H10 methylcubane molecule

The thermal stability of the C₉H₁₀ methylcubane molecule was studied over the temperature range 1100–2100 K by molecular dynamics simulation with the tight binding potential. The temperature dependence of its lifetime to the decomposition moment was determined. The activation energy E _a = 1.7 ± 0.2 eV and frequency factor A = 10^{15.63 ± 0.53} s^?1 of the Arrhenius equation were found. Possible channels and final products of molecule decomposition were studied.     

Preionization effects of iso-C4H10 in N2 TE UV lasers

In this paper the ionizing role of isobutane (iso-C₄H₁₀) in the operation of a N₂TE UV laser is analyzed. Laser pulse width value modifications, different laser wavelengths generated in the 2⁺ system and voltage pulse period modifications are analysed in order to show that isobutane, in very reduced quantities, generates a preionizing effect that can be higher than that produced by a conventional wire preionization system.     

Studying the effect of hydrogen on diamond growth by adding C10H10Fe under high pressures and high temperatures

In this paper, hydrogen-doped industrial diamonds and gem diamonds were synthesized in the Fe–Ni–C system with C₁₀H₁₀Fe additive, high pressures and high temperatures range of 5.2–6.2?GPa and 1250–1460°C. Experimental results indicate similar effect of hydrogen on these two types of diamonds: with the increasing content of C₁₀H₁₀Fe added in diamond growth environment, temperature is a crucial factor that sensitively affects the hydrogen-doped diamond crystallization. The temperature region for high-quality diamond growth becomes higher and the morphology of diamond crystal changes from cube-octahedral to octahedral. The defects on the {100} surfaces of diamond are more than those on the {111} surfaces. Fourier transform infrared spectroscopy (FTIR) results indicate that the hydrogen atoms enter into the diamond crystal lattice from {100} faces more easily. Most interestingly, under low temperature, nitrogen atoms can also easily enter into the diamond crystal lattice from {100} faces cooperated with hydrogen atoms.     

Dissociative charge exchange in collisions of 10keV H 2 + ions on H2, He,and Ar targets

The velocity distributions of H-H fragment pairs arising from dissociative collisions of 10keV H ₂ ⁺ ions incident on H₂, He, and Ar were measured using a flight-time-difference method. The H ₂ ⁺ ions were produced in an electron impact ion source at two different electron energies, at 100eV and 18eV. The influence of the electron energy on the fragment velocity distributions is studied. Conclusions are drawn on the processes which lead to the formation of neutral fragment pairs. Electron capture into the repulsive b³ Σ _u ⁺ state of H₂ plays a dominant role.     

辛烷基苯酚聚氧乙烯醚与正癸醇层状液晶的有序性及层状结构

研究了层状液晶的层状结构及有序性,用偏振光显微镜法确定了辛烷基苯酚聚氧乙烯醚(TritonX 100)与正癸醇体系25℃时层状液晶的区域,绘制了部分相图,并用核磁共振氢谱法(2H NMR)进一步验证;用自旋标记电子自旋共振法测定了层状液晶分子排列的有序参数,研究结果显示,不同组分TritonX 100 /n C10H21OH/H2O体系层状液晶的超精细偶合常数基本相同,表明层状液晶中的微极性是一致的.而有序参数随着TritonX 100含量的增加而增加,随着层状液晶中水含量的增加而减少;用小角度X射线衍射方法测定了层状液晶的层间距离,并计算了水分子在层状液晶中的渗透率,其渗透率约为50%.     

Vibrational spectra of Na4P2O7·10H2O

The IR and Raman spectra are measured and analysed for sodium pyrophosphate decahydrate. The spectra are interpreted on the basis of P₂O ₇ ⁴⁻ ion and water vibrations. The observed results fit with the features predicted for the factor goup model. The appearance of two sets of frequencies in the stretching and bending regions of water suggests the existence of two kinds of water molecules in the crystal. This is confirmed by deuterium substitution.     

HF-laser performance of CO2-laser-ignited mixtures of SF6 :H2 and of S2F10 :H2

We have used a CO₂ laser to ignite mixtures of SF₆ :H₂ and S₂F₁₀ :H₂. We observed HF lasing from these mixtures when an optical resonator was constructed around the reaction cell. The HF-lasing performance of the two mixtures was compared as a function of mixture ratio, fluorine-donor pressure, and CO₂-laser frequency. Under comparable conditions, the HF-laser output for S₂F₁₀ :H₂ mixtures was typically 5–6 times greater than that for SF₆ :H₂ mixtures. Spectral output of the HF laser was coarsely resolved to provide data about the vibrational and rotational states of the HF molecule.     

Method of H1(10) evaluation using a spherical-type energy-independent neutron dose monitor

A spherical-type neutron dose monitor has been developed for the use of area monitoring around the neutron producing fields. Considering the practical fields that neutrons coming from multiple directions, the study has been performed using MCNP simulation, in order to estimate the resultant direction of the sources and to find a suitable method of H¹(10) evaluation. This was done by irradiating the monitor using two neutron sources of different energies and intensities; placed at an angle between them. A parallel neutron beam of 50 cm radius with wide energy was used for the irradiation. The direction of the neutron sources was determined comparing the responses of 12 thermo-luminescent detectors (TLDs) of first layer between single and two directional sources. It was found that in most of the cases, the direction of the source was estimated to be the average angle or near the average angle of single sources. Using a linear combinational equation the method has been developed for evaluating the dose from the mean values of selected detectors of two consecutive depths of TLDs and the TLD of core depth. It was found that the ratio of the calculated to the expected dose was almost close to unity which indicates that the method can be used for evaluating the dose with good accuracy.