Kinetic theory of dense fluids. II. The generalized Chapman-Enskog solution

In the second paper of this series we solve the kinetic equation proposed in the previous paper by a method following the spirit of Chapman and Enskog (generalized Chapman-Enskog method). The zeroth-order solution to the kinetic equation leads to the Euler equations in hydrodynamics for real fluids, and the first-order solution to the Navier-Stokes equations for real fluids. General formulas for transport coefficients such as viscosity and heat-conductivity coefficients are obtained for dense fluids, which are given in terms of time-correlation functions of fluxes conjugate to the thermodynamic forces. The results have the same formal structures as the time-correlation functions in linear response theory except for the collision operator appearing in place of the Liouville operator in the evolution operator for the system.     

Hinge peptide combinatorial libraries for inhilbitors of botulinum neurotoxins and saxitoxin: Deconvolution strategy

Combinatorial library screening offers a rapid process for identifying potential therapies to toxins. Hinge peptide libraries, which rely on conformational diversity rather than traditional molecular diversity, reduce the need for huge numbers of syntheses and screening steps and greatly expedite the discovery process of active molecules. Hinge peptide libraries having the structures: Acetyl-X₁–X₂–hinge–X₃–X₄–NH₂ (capped) and X₁–hinge–X₂–X₃ (uncapped), where X₁ through X₄ are near-equimolar mixtures of twelve L-amino acids and hinge = 4-aminobutyric acid, were screened for inhibitory activity in bioassays for botulinum neurotoxins A and B (BoNT/A, BoNT/B) and saxitoxin. The zinc protease activity of the reduced light chains of BoNT/A and /B was assayed by measuring the cleavage of synthetic substrates. Saxitoxin activity was measured by the restoration of the viability of neuroblastoma cells treated with ouabain and veratridine. Deconvolution of libraries was accomplished by fixing one position at a time beginning with the C-terminus. Primary library subsets in which position 4 was fixed showed moderate levels of inhibition for BoNT/A. Secondary library subsets showed stronger inhibition in the bioassays. In each of the bioassays, inhibitory potency was stronger when the second position to be fixed was on the opposite side of the hinge, rather than on the same side with respect to the C-terminus, suggesting that the hinge facilitates the interaction of side chains. Inhibitors for all three of the toxins studied were discovered within library subsets, although not necessarily in primary subsets. These studies demonstrate that (1) the best strategy for deconvoluting hinge peptide libraries is by fixing residues alternately on each side of the hinge moiety, and (2) it is essential to investigate secondary subsets even when primary subsets are inactive. The present findings support the concept that the increased flexibility imposed by the inclusion of a central hinge residue in small peptides increases the opportunity for side chain interactions, providing a distinct advantage for hinge peptide libraries over conventional peptide libraries. Hinge peptide libraries are a rich source of novel ligands for modulation of biomechanisms. The library subsets uncovered in this study may possess peptides that will lead to effective therapies to neurotoxin poisoning.     

Novel Fluorometric Turn On Detection of Aluminum by Chalcone-Based Chemosensor in Aqueous Phase

A novel, 100% water-soluble chalcone based chemosensing receptor {1-[3-(2-Hydroxy-phenyl)-3-oxo-propenyl]-naphthalen-2-yloxy}-acetic acid, L was synthesized and characterized. The receptor L is designed based on the chelation enhanced fluorescence (CHEF) mechanism. The chemosensing properties of L were evaluated by UV–vis and fluorescence spectrometric methods. It exhibits highly selective recognition ability towards aluminum ions in water over other metal ions. The binding stoichiometry of L? Al³⁺ complex is 2:1 by means of Job’s plot and the detection limit is 5.66?×?10^??8 M.     

Gauge and Bäcklund transformations for the generalized sine-Gordon equation and its η-dependent modified equation

We study the generalized sine-Gordon hierarchy and its associated-dependent modified sine-Gordon hierarchy. Two Bäcklund transformations for these two families are constructed. One of them is a generalization of the Bäcklund transformations of Wadatiet al. and the other one is new. Gauge transformations of a relevant AKNS system are employed to reduce the integration of these equations via the Bäcklund transformations to quadratures. Three generations of explicit solutions of the sine-Gordon equation are presented.     

Some New Features in the Pseudoscalar Meson and Vector Meson Photoproductions

We investigate the role of the t-channel meson exchange in various photoproduction processes to discuss features of the respective production mechanism. For the less model-dependent analysis we work with the t-channel meson pole reggeized in the Born approximation amplitude. With the meson–baryon coupling constants chosen consistently with symmetry prediction we show that the Reggeized pole model could reproduce the experimental data to a good degree in the lower energy region. Numerical consequences show the significance of the tensor meson exchange in the γ p → K ⁺Λ, the dominance of the pseudoscalar meson exchange in the πΔ (and KΣ*) processes, and the sizable role of the vector-meson magnetic moment in the charged ρ (and K*) photoproductions, respectively. These new features from the present analyses could provide a useful guide for future study of the N* resonances in the low energy region.     

食品中铝的测定及超标对人体的危害

用分光光度法测定了油炸食品、膨化、威化、面包粉、海蜇中的铝含量.利用Al3+在乙二胺-盐酸溶液缓冲介质中,与铬天青S及溴代十六烷基吡啶(CPB)反应形成蓝绿色四元胶束,在620nm处测定其吸光度,并对CPB质量浓度进行了最佳选择.结果表明,该法提高了测定灵敏度.5种类型的样品中,海蜇的铝含量最高;面包粉的铝含量最少.此方法允许pH值范围宽、稳定性好、操作简便,测定食品中微量铝得到较好的精密度和准确度.     

A non-linear fluid force model for vortex-induced vibration of an elastic cylinder

Even under the assumption of a sinusoidal lift and drag force at a single frequency for a stationary cylinder in a cross flow, higher harmonics that represent non-linearity in the fluid-structure interaction process are present. This fact is considered in the formulation of a non-linear fluid force model for a freely vibrating cylinder in a cross flow. The force model is developed based on an iterative process and the modal analysis approach. The fluid force components in the model can be evaluated from measured vibration data with the help of the auto-regressive moving averaging (ARMA) technique. An example is used to illustrate that non-linear (higher order) force components are present at resonance, even for a case with relatively weak fluid-structure interaction. Further analysis reveals that the fluid force components are dependent on structural damping and mass ratio. The non-linear fluid force model is further modified by taking these considerations into account and is used to predict the dynamic characteristics of a freely vibrating cylinder over a range of Reynolds numbers, mass and structural damping ratios. On comparison with measurements obtained from four different experiments and predictions made by previous single-degree-of-freedom model, good agreement is found over a wide range of these parameters.     

Piezoelectric PMN-PT fibre hydrophone for ultrasonic transducer calibration

A newly developed ceramic fibre hydrophone with an active element as small as 0.25 mm in diameter is described in this work. Lead magnesium niobate-lead titanate (PMN-PT) ceramic fibre with a nominal composition of 0.65Pb(Mg_1/3Nb_2/3)O₃-0.35PbTiO₃ was fabricated by an extrusion method. PMN-PT single crystals were ground to a powder form and then mixed with poly(acrylic) acid to form a homogenous slurry. The fibre was extruded by pressing the slurry through a spinneret and then sintering at 1250 °C for crystallization. The electrical characteristics of the PMN-PT fibre were evaluated by measuring the relative permittivity and the impedance spectrum. A piezoelectric PMN-PT fibre hydrophone was fabricated and its sensitivity, angular response, and spatial resolution were evaluated. The fibre hydrophone provides good spatial resolution, angular response and receiving sensitivity. PACS 43.58.+z; 77.84.Dy     

基于宽带多通道的光谱反射率重建方法研究

复制的多光谱数据获取要求图像数据具有设备无关、场景无关特性,能够真实客观表征物体颜色信息。针对获取系统扰动、噪声误差以及光谱重建中训练样本典型代表性与相关性要求,提出了基于正交回归的光谱重建算法,并通过子空间跟踪的训练样本选择算法,选择重建样本与训练样本集中相关性与代表性最好的样本参与光谱重建。实验通过改造后的仙娜宽带多通道成像系统进行验证,数据表明本文提出的方法,所选训练样本能较好的表征样本空间并具有较好的正交性,在宽带多光谱成像方面,重建光谱平均色度误差为3.6,其光谱精度与色度精度较其他方法具有明显提高。