Interaction of –CClx (x=1–3) with Ru2 and RuSn dimers: a density functional study

Density functional calculation were performed on the Ru₂ and RuSn metal dimers and the species formed from their interaction with –CCl_x (x=1–3) fragments. The importance of these fragments in the hydrodechlorination of carbon tetrachloride has been motivated this study aiming to contribute to understand the effect of the tin in the performance of the noble metals based catalysts. We have observed that the carbon tetrachloride does not form a precursor with the metal dimers. The CCl₄ readily dissociates forming adsorbed chlorine and –CCl₃ complexes. The chlorine atoms prefer to adsorb on the bridge sites and the RuSn–Cl binding energy is about 5 kcal mol⁻¹ larger than the Ru₂–Cl binding energy. The Ru₂–CCl_x (x=1–3) binding energies are larger than the respective RuSn–CCl_x (x=1–3) binding energies. However, the reaction energy of the dechlorination of CCl₄ leading to adsorbed –CCl_x (x=1–3) and chlorine is thermodynamically more favorable for RuSn than the Ru₂. The differences between Ru₂ and RuSn systems have been discussed based on the different interaction mechanism due to the presence of the tin center and its affinity for the chlorine atoms.     

三电极共面介质阻挡放电的放电特性及诱导气流实验研究

等离子体流动控制激励器由于其响应速度快、激励频带宽、能量损耗低、可靠性强的优势,在航空航天领域的主动流动控制等方面得到了广泛应用.文章提出了一种新型的等离子体气动激励器——三电极共面介质阻挡放电激励器,研究了该激励器电极结构对放电特性和诱导气流速度的影响,并与传统共面介质阻挡放电和沿面介质阻挡放电激励器进行了比较.结果表明:（1）随着激励电压的提高,高压电极和地电极之间先出现了丝状放电并逐渐延伸到第三电极;（2）随着第三电极与高压电极之间的距离增大,诱导气流速率从2.4 m/s下降到0 m/s,而第三电极宽度的变动对诱导气流速度影响可忽略不计;（3）相同外部条件下,该激励器诱导的气流速度小于沿面介质阻挡放电激励器,但高于共面介质阻挡放电激励器.      

Studies of molecular oxygen adsorbed on Cu surfaces

Molecular oxygen adsorbed on (110) and polycrystalline Cu surfaces has been investigated by UPS, XPS, AES, HREELS and LEED. Molecularly adsorbed O₂ on the (110) surface shows the characteristic three-peak He II spectrum due to π_g, π_u and σ_g orbitals, accompanied by an O-O stretching frequency at 660 cm⁻¹. On the polycrystalline Cu surface, adsorbed O₂ shows the three peak He II spectra with a considerably smaller separation between the π_u and σ_g band and two O-O stretching bands at 610 and 880 cm⁻¹. O₂ adsorbed on the Cu(110) surface gives rise to a (1 × 1) LEED pattern and characteristic K π¹π¹ transition in the Auger spectrum.     

Comparative infrared study of silicon and germanium nitrides

Silicon and germanium nitride (Si₃N₄ and Ge₃N₄) are isomorphic compounds. They have been studied in the β-phase which crystallises in the hexagonal system. The space group is P6₃/m (C_6h²).The IR transmission spectra of these two nitrides are very similar but the absorption frequencies of germanium nitride are shifted to the lower values in comparison with silicon nitride. We noted that the atomic mass effect is the only cause of this shift for the streching modes but not for the bending modes.     

血液可见吸收光谱与血氧参数神经网络估算法

总血红蛋白浓度和血氧饱和度是两个基本的血氧参数。文章提出了利用内置双光纤微创探头在位测量大鼠脑组织血氧参数的新方法。首先,利用悬乳液(Intralipid)和全血配置不同总血红蛋白浓度的混合溶液,模拟生物组织模型,用光纤光谱仪测试系统测量组织模型在加氧和去氧时的实时吸收光谱,同时用血氧分析仪(OXI meter)对血氧参数定标,建立测试光谱和定标数据样本集。然后,利用人工神经网络建立血液吸收光谱与血氧参数的神经网络模型,训练后的网络模型能根据吸收光谱输出生物组织的血氧参数值,总血红蛋白浓度和血氧饱和度的平均输出误差分别为±4μmol·L-1和±5%。最后,利用神经网络模型对大鼠脑组织血氧参数进行了在位测试实验,测得脑灰质的血氧饱和度为0.60~0.70,脑白质血氧饱和度为0.45~0.55;总血红蛋白浓度在脑皮层(深度1mm)附近最高,平均110μmol·L-1,其余深度脑组织的总血红蛋白浓度为70~90μmol·L-1。这种方法对脑外科微创手术中实时在位测试脑组织血氧参数具有重要的参考意义。     

General method for the photogeneration of benzolated cationic and anionic systems in aqueous solution. Test of relative stability of these systems in the excited state.

A general method for the photogeneration of dibenzolated carbocations and carbanions is described with the aim of testing the relative stabilty of these species as a function of number of pi-electrons in the excited state.     

Heat transfer limitation in a vertical annular closed two-phase thermosyphon with small fill rates

A thermosyphon with R113 as the working fluid employing fill ratios between 0.02 and 0.4, i.e. 2 and 40% of the evaporator volume, was experimentally and theoretically investigated. A critical heat flux (for which dry-out occurs) was measured which increases from about 10⁴W m⁻² at 5% fill ratio to about 5 × 10⁴W m⁻² at 40% fill ratio. The theoretical predictions are in close agreement with the experimental results.     

基于特征值方法的旋翼尾迹稳定性分析

给出一个旋翼尾迹线性化稳定性分析的方法.在该方法中,尾迹涡线被离散为直线涡段,尾迹的扰动归结为涡元端点的扰动,考虑了桨尖涡的自诱导和涡线的互诱导以及桨尖涡与桨叶的实际干扰.使用该方法,分别以UH-1H和AH-1G模型旋翼为例,对悬停和前飞状态的旋翼尾迹的稳定性进行计算和分析.结果表明:旋翼尾迹运动存在大于0的特征值,是内在不稳定的,且最大发散率随波数变化呈现出一定规律性;前飞与悬停状态不同,其最大发散率减小,不稳定性减弱.