A high-speed high-sensitivity acoustic cell for in-line continuous monitoring of MOCVD precursor gases

We describe a continuous wave resonant acoustic sensor that has been optimized as a very sensitive in-line monitor for measuring the composition of precursor gases used in MOCVD processes. The precursor/carrier gas mixtures flow through a compact stainless steel acoustic chamber that is isolated from the acoustic transducers by a set of metallic diaphragms. The sensor has been successfully operated at supply line pressures from atmosphere down to 50 Torr with gas flow rates of up to 1600 sccm. The accuracy of the speed of sound measurement for hydrogen gas is better than 0.005%, even in a high noise and low pressure environment. Hydrogen, as well as nitrogen or argon carrier gases, are accommodated within the instrument's 1–5 kHz working frequency range. The instrument's sensitivity and stability are demonstrated with the laboratory data. Measurements of the dynamic response characteristics of the metalorganic bubbler lines at low pressure are also be presented. Application of the cell is general, encompassing any of the metalorganic and hydride materials typically used in MOCVD processes.     

用玻色子组态混合和玻色子表面δ相互作用研究核谱

用玻色子组态混合波函数和玻色子表面δ相互作用研究了三玻色子核⁴⁶Ti和⁵⁴Cr的sdgIBMI的能谱和E2跃迁概率,理论计算结果令人满意,比sdIBMI能拟合出更多的能级和E2跃迁概率,而且它们的误差更小. 说明g玻色子在振动区也起着重要的作用,同时进一步证明了这种玻色子组态混合模型是成功的.     

Hydrolysis of palm kernel olein in AOT-isooctane-water reversed micelles

Rhizopus arrhizus lipase (EC 3.1.1.3; triacylglycerol hydrolase) was used in this study to investigate the hydrolysis of palm kernel olein in AOT-isooctane-water reversed micelle system at W_o = 13, pH = 7, and T = 30?C. The hydrolytic reaction obeys Michaelis-Menten kinetics for substrate concentrations in the range (0.175 and 0.877M). The apparentK _m and V_max for the substrate were 0.397M (equivalent to 9.06% w/v) and 5523 U/mg protein, respectively. Product inhibition with a dissociation constant of the enzyme-product complex,K _I = 9.74 mM, was confirmed. Experimental results from the change of product concentrations with respect to time correlated sufficiently with those predicted theoretically from the rate equation for a reaction time up to 100 min. However, the discrepancy between the observed results and the predicted ones would increase with reaction time. Possible reasons for this deviation were discussed.     

不同温度均匀二半空间接触后产生的辐射场

 应用电磁线路中涨落耗散理论，推导了不同温度均匀二半空间接触后产生辐射场密度的公式。将此公式近似展开后，即得Grover和Urtiew所获得的表示式，不过多了一松弛项，该项如用非富里叶热传导理论推导，也是存在的。该结果和实验结果一致，不过这里的松驰时间可以应用介质性质进行计算。     

全息透镜在车辆中的两种应用

通过把全息透镜嵌入挡风玻璃，实现全息透镜在车辆中的两种应用，即将具有颜色选择性的窄带全息透镜用于车辆的平视显示，将具有角度选择性的宽带全息透镜用于车辆的阳光防护。     

Focusing-defocusing phenomena of radio echo signal after passage of the morning solar terminator

Summary Campaign results of high-repetition ionospheric soundings, performed at the ionospheric station of Rome using a Digisonde 128P, are presented. We introduce an index derived from run rapid ionograms that can be used to detect oscillations of isodensity surfaces ofF ionospheric region started by morning solar terminator.     

光放大器前置可调光学滤波器

介绍Ｆ－Ｐ干涉滤波器实现中心波长可调的两种机理，给出通过改变腔距来改变中心波工的滤波器的典型结构，并且给出了相应的电压驱动电路，实验表明选择合适的光放大器前置滤波器可以提高系统的灵敏度。     

Substitution of calcium by strontium within selected calcium phosphates

Sr incorporation in the molecules of amorphous calcium phosphate, apatitic tricalcium phosphate, hydroxyapatite, octacalcium phosphate and dicalcium phosphate dihydrate was investigated. The concentration of Sr ranged from 225 to 1010 μ g / g, i.e. it overlapped with the physiological range of Sr concentrations in human bone. The leading experimental technique was extended X-ray absorption fine structure (EXAFS) at the Sr K edge. Results of these studies demonstrated the following: (1) Sr incorporation in the calcium phosphates is compound-dependent, (2) the coordination of incorporated Sr atoms in the Ca-P molecules is similar to that of Ca atoms, but interatomic distances are ≈0.015 nm larger, (3) in apatitic tricalcium phosphate, hydroxyapatite and octacalcium phosphate lattices Sr atoms may occupy selected Ca sites, which was not the case for dicalcium phosphate dihydrate, (4) in the apatite lattice Sr atoms are coordinated by 6 PO₄ tetrahedrals and (5) EXAFS spectra at the K edge of the incorporated Sr may be used to distinguish the structures of amorphous calcium phosphate, dicalcium phosphate dihydrate as well as apatite and its derivatives (apatitic tricalcium phosphate, octacalcium phosphate).