Calibration of quartz load cells; An in-situ procedure for instrumented falling weight impact machines

Quartz load cells have particular problems concerning signal drift and time of load application during calibration. There is currently no available standard method for dealing with these problems. A procedure is suggested that may be used as a routine check in situ on the complete system of quartz cell, amplifier, recording device and data processing unit. It involves loading and unloading a quartz cell with a known mass, recording the output on a suitable storage device and manipulating the data with a computer program to provide a permanent record. The accuracy of the method is considered and the results of a comprehensive series of calibrations in tension and compression are reported.

It was found that, providing good axiality was obtained, then either tensile or compressive loading gave the same calibration. The preferred method was to apply a tensile load, via a hanger system on the end of the striker, which obviates any necessity to remove the load cell from the impact mass and avoids possible errors associated with non-axial loading. Using the procedure, the quartz load cell was calibrated to an accuracy of better than 0·1%.     

Magic-angle spinning solid-state NMR spectroscopy of the beta1 immunoglobulin binding domain of protein G (GB1): 15N and 13C chemical shift assignments and conformational analysis

Magic-angle spinning solid-state NMR (SSNMR) studies of the beta1 immunoglobulin binding domain of protein G (GB1) are presented. Chemical shift correlation spectra at 11.7 T (500 MHz 1H frequency) were employed to identify signals specific to each amino acid residue type and to establish backbone connectivities. High sensitivity and resolution facilitated the detection and assignment of every 15N and 13C site, including the N-terminal (M1) 15NH3, the C-terminal (E56) 13C', and side-chain resonances from residues exhibiting fast-limit conformational exchange near room temperature. The assigned spectra lend novel insight into the structure and dynamics of microcrystalline GB1. Secondary isotropic chemical shifts report on conformation, enabling a detailed comparison of the microcrystalline state with the conformation of single crystals and the protein in solution; the consistency of backbone conformation in these three preparations is the best among proteins studied so far. Signal intensities and line widths vary as a function of amino acid position and temperature. High-resolution spectra are observed near room temperature (280 K) and at <180 K, whereas resolution and sensitivity greatly degrade substantially near 210 K; the magnitude of this effect is greatest among the side chains of residues at the intermolecular interface of the microcrystal lattice, which we attribute to intermediate-rate translational diffusion of solvent molecules near the glass transition. These features of GB1 will enable its use as an excellent model protein not only for SSNMR methods development but also for fundamental studies of protein thermodynamics in the solid state.     

A study of the thermal and light induced spin transition in [FeL2](BF4)2 and [FeL2](ClO4)2 L=2,6-di(3-methylpyrazol-1-yl)pyrazine

The spin crossover compounds [FeL2](BF4)2, L=2,6-di(3-methylpyrazol-1-yl)pyrazine and [FeL2](ClO4)2 have very unusual two stage spin transitions which are initially steep and then become more gradual. A detailed variable temperature single crystal X-ray diffraction study has shown that the course of the spin transition is controlled by an order-disorder transition in the counter anions. The high and low spin states both crystallise in the tetragonal space group I4, the structures of the high and low spin states are presented at 290 and 30 K, respectively. The title compounds are shown to undergo LIESST (Light Induced Excited Spin State Trapping) under irradiation with either red or green laser light with wavelengths of 632.8 and 532.06 nm, respectively, at 30 K. The cell parameters for the tetragonal photo-induced metastable high spin state at this temperature are a= 9.169(6), c= 17.77(1) A for [FeL2](ClO4)2 with an increase in unit cell volume of 21 A3, and a= 9.11(1), c= 17.75(2) A and an increase in volume of 42.8 A3 for [FeL2](BF4)2.     

Higher order symmetrizer and application to an unusual transport equation

We study a class of stationary transport equation with nonlocal low-order tems We obtain the existence and uniqueness of a solution in sobolev spaces     

Probing the beta-1,3:1,4 glucanase, CtLic26A, with a thio-oligosaccharide and enzyme variants

The substrate binding regions of a beta-1,3:1,4 glucanase are revealed through structural analysis with a thio-oligosaccharide and kinetics of enzyme variants.     

求解复杂湍流的非线性涡黏性系数模型和代数应力模型

非线性涡黏性系数模型和代数应力模型联系了线性涡黏性系数湍流模型和完整的微分 雷诺应力模型.随着它们受到日益关注,其形式也越来越多样化.本篇综述的目的是对这些模 型加以总结并比较它们之间的共同点及不同之处,指出它们与完整微分雷诺应力模型之间的 关系,以及相对于线性涡黏性系数模型而言它们在预报流场上所具有的优势.     

An enantiospecific synthesis of estrone

Efficient ring cleavage of 9,10-dibromocamphor (3) provides a monocyclic hydroxyacid (5) which can serve as an intermediate in a new enantiospecific synthesis of estrone.