双折射双频激光器偏振特性的分析

用激光原理和晶体光学原理分析了腔内加旋光晶体的激光器输出光的偏振特性，实验和分析表明，激光器输出两束不同频率的垂直线偏振光，激光器两端输出光的偏振面有一夹角ａ，且此夹角与晶轴和传光方向的夹角θ有关。理论计算结果在双折射双频激光器的实验结果符合很好。     

微通道板增益疲劳机理研究

微通道板的增益疲劳是微通道板的主要问题之一，本文分析了微通道板的表面结构模型，同通道板活性表面上碱金属的逸出和碳的增加是导致微通道板的增益疲劳的主要原因，另外，探讨碱金属逸出的机理和碳污染的来源，介绍延长微通道板工作寿命的有效方法。     

Deposition of Oral Bacteria and Polystyrene Particles to Quartz and Dental Enamel in a Parallel Plate and Stagnation Point Flow Chamber

The aim of this paper is to determine to what extent (i) deposition of oral bacteria and polystyrene particles, (ii) onto quartz and dental enamel with and without a salivary conditioning film, (iii) in a parallel plate (PP) and stagnation point (SP) flow chamber and at common Peclet numbers are comparable. All three bacterial strains showed different adhesion behaviors, and even Streptococcus mitis BMS, possessing a similar cell surface hydrophobicity as polystyrene particles, did not mimic polystyrene particles in its adhesion behavior, possibly as a result of the more negative ζ potentials of the polystyrene particles. The stationary endpoint adhesion of all strains, including polystyrene particles, was lower in the presence of a salivary conditioning film, while also desorption probabilities under flow were higher in the presence of a conditioning film than in its absence. Deposition onto quartz and enamel surfaces was different, but without a consistent trend valid for all strains and polystyrene particles. It is concluded that differences in experimental results exist, and the process of bacterial deposition to enamel surfaces cannot be modeled by using polystyrene particles and quartz collector surfaces.     

Optimum gas chromatographic conditions in wall-coated capillary columns. Extended and simplified forms of the Golay-equation

Band broadening in capillary columns is satisfactorily described by the Golay-equation extended to situations of appreciable pressure drop by Giddings. In practice, however, several simplifications are often made. The effect of these simplifications on the calculated values of the minimum plate height and optimum carrier gas velocity are treated systematically.     

Measurement of attachment force of microbial cells

A parallel-plate flow chamber consisting of two transparent electro-conductive glass plates was constructed. The two glass plates were set parallel to each other and connected to a potentiostat apparatus to regulate the strength of the electric field between the plates. A microbial cell suspension was flowed through the chamber. This system enabled the application of an electrostatic force to suspend charged particles, e.g. microbial cells, existing between the two plates. The time course of the cell attachment of Pseudomonas syringae pv. atropurpurea NIAES 1309 suspended in 10 mM phosphate buffer solution (pH 7.0) to the glass plate was investigated at various electric field strengths ranging from −4.2 to +4.1 V cm⁻¹. The attachment rate and the maximum number of attached cells increased linearly with the increase in the strength of the positive electric field. In contrast, the rate and the number of cells decreased linearly with the decrease in the strength of the negative electric field. These linear relations gave a specific value for the strength of the electric field (−5.9 ± 0.7 V cm⁻¹) where the electrostatic repulsion and the microbial attachment force were thought to be equal, resulting in no cell attachment. From this value, the electrostatic repulsion, i.e. the microbial attachment force, was calculated to be 5.0 × 10⁻¹¹ N cell⁻¹ for cells of average size.     

Rapid quantification of HIV protease inhibitors in human plasma by high-performance liquid chromatography coupled with electrospray ionization tandem mass spectrometry

HIV protease inhibitors are important antiretroviral drugs which have substantially reduced the morbidity and mortality associated with HIV-1 infection. Recent data have shown relationships between plasma concentrations of the protease inhibitors and clinical response, which makes therapeutic drug monitoring valuable. We have developed and validated an assay, using liquid chromatography coupled with electrospray tandem mass spectrometry (LC/MS/MS), for the routine quantification of the six licensed protease inhibitors (amprenavir, indinavir, lopinavir, nelfinavir, ritonavir and saquinavir) and the pharmacologically active nelfinavir metabolite M8 in plasma. The sample pretreatment consisted of protein precipitation with a mixture of methanol and acetronitrile using only 100 microl of plasma. Chromatographic separation was performed on an Inertsil ODS3 column (50 x 2.0 mm i.d., particle size 5 microm), with a quick stepwise gradient using an acetate buffer (pH 5) and methanol, at a flow rate of 0.5 ml min(-1). The analytical run time was 5.5 min. The use of a 96-well plate autosampler allowed batch sizes up to 150 patient samples. The triple-quadrupole mass spectrometer was operated in the positive ion mode and multiple reaction monitoring was used for drug quantification. The method was validated over the concentration ranges 0.01-10 microg ml(-1) for indinavir and saquinavir, 0.1-10 microg ml(-1) for amprenavir, 0.05-10 microg ml(-1) for nelfinavir and ritonavir, 0.1-20 microg ml(-1) for lopinavir and 0.01-5 microg ml(-1) for M8. Saquinavir-d(5) and indinavir-d(6) were used as internal standards. The coefficients of variation were always <10% for both intra-day and inter-day precisions for each compound. Mean accuracies were also between the designated limits (+/-15%). The validated concentration ranges proved to be adequate in daily practice. This robust and fast LC/MS/MS assay is now successfully applied for routine therapeutic drug monitoring and pharmacokinetic studies in our hospital.     

重氮树脂与十二烷基硫酸钠相互作用研究

重氮树脂与十二烷基硫酸钠相互作用研究罗杨磊曹维孝（北京大学化学与分子工程学院北京１００８７１）关键词重氮树脂，十二烷基硫酸钠，负性ＰＳ版随着化学与生命科学领域的发展，大分子与小分子在溶液的相互作用越来越受到关注．表面活性剂因其具有自组装能力，...     

LOWLAD: a locally weightedL 1 smoothing spline algorithm with cross validated choice of smoothing parameters

The computation ofL ₁ smoothing splines on large data sets is often desirable, but computationally infeasible. A locally weighted, LAD smoothing spline based smoother is suggested, and preliminary results will be discussed. Specifically, one can seek smoothing splines in the spacesW _m (D), with [0, 1] ⁿ D. We assume data of the formy _i =f(t _i )+ _i ,i=1,..., N with {t _i } _i=1 ^N D, the _i are errors withE( _i )=0, andf is assumed to be inW _m . An LAD smoothing spline is the solution,s , of the following optimization problem

AnL 1 smoothing spline algorithm with cross validation

We propose an algorithm for the computation ofL ₁ (LAD) smoothing splines in the spacesW _M (D), with . We assume one is given data of the formy _i =(f(t _i ) + _i , i=1,...,N with {itt_i} _i=1 ^{N D} , the _i are errors withE( _i )=0, andf is assumed to be inW _M . The LAD smoothing spline, for fixed smoothing parameter0, is defined as the solution,s , of the optimization problem (1/N) _i=1 ^N ¦y _i –g(t _i ¦+J _M (g), whereJ _M (g) is the seminorm consisting of the sum of the squaredL ₂ norms of theMth partial derivatives ofg. Such an LAD smoothing spline,s , would be expected to give robust smoothed estimates off in situations where the _i are from a distribution with heavy tails. The solution to such a problem is a thin plate spline of known form. An algorithm for computings is given which is based on considering a sequence of quadratic programming problems whose structure is guided by the optimality conditions for the above convex minimization problem, and which are solved readily, if a good initial point is available. The data driven selection of the smoothing parameter is achieved by minimizing aCV() score of the form .The combined LAD-CV smoothing spline algorithm is a continuation scheme in 0 taken on the above SQPs parametrized in, with the optimal smoothing parameter taken to be that value of at which theCV() score first begins to increase. The feasibility of constructing the LAD-CV smoothing spline is illustrated by an application to a problem in environment data interpretation.     

The theoretical basis of column chromatography in multicomponent separations. Part 2: Peak capacity. Column systems with good selectivity

The selectivity of a column system, S, defined by equation 28, includes a variation coefficient (β) of plate number with capacity ratio which has a large influence on the peak capacity, as shown in Fig. 18. Some typical chromatograms are given. In order to predict S for a column system from Kovat's Index, equations 40 and 41 are given to calculate the constant of the carbon number rule for squalane at different temperatures or for different stationary phases. The specific retention value of heptane on squalane at different temperatures can be calculated from equation 42. The nonpolarity index, defined by equation 43, was used to calculate the retention value of heptane on various stationary phases. In liquid chromatography, the order of elution may be reversed by changing the composition of the eluent on the same chemically bonded silica (manufactured in China). The linear relations between the log retention values of different kinds of solutes or of a single solute on the silicas of different surface areas when using the same eluent are given.