Molecular orbital study of the bridge bonding in an electron deficient molecule [(CH3)2ALH]2

The electronic distribution in the AlH₂Al bridge of the dimethyl aluminium hybride dimer was computed through ab initio SCF calculation. Comparison with diborane shows an increased role of the ionic Al⁺H ₂ ^2– Al⁺ structures with respect to the usual covalent three-center bonds.     

Tethering versus Non‐Coordination of Hydroxy and Methoxy Side Chains in Arene Half Sandwich Dichloro Ruthenium Complexes

We are reporting on the hydroxyalkyl appended arene ruthenium half sandwich complexes [{η⁶‐C₆H₅(CH₂)_nOH}RuCl₂] (n = 2, 3) and the methyl ether of the hydroxypropyl derivative. Most significantly, a structural comparison between the hydroxypropyl complex 1a and its methyl ether 2a reveals, that the latter adopts the conventional dichloro bridged dimeric structure while 1a is a monomer. Coordinative saturation of the ruthenium centre is achieved by intramolecular coordination of the appended hydroxy function, thus rendering the functionalized arene an eight electron donor chelate ligand. The structure is further stabilized by intermolecular OH···Cl hydrogen bridges between a terminal chloride ligand of one and the coordinated hydroxy group of a neighbour molecule, resulting in a sheet structure. These intermolecular interactions appear to be even stronger in the hydroxyethyl analogue. Several phosphine adducts have been prepared from the hydroxy or alkoxy functionalized [(η⁶‐arene)RuCl₂]_n precursors, including water soluble P(CH₂OH)₃ adducts. Electrochemical properties of the phosphine adducts and of the dichloro bridged aryl ether complex 2a are also discussed.     

A highly sensitive and specific enzyme immunoassay for detection of β-amanitin in biological fluids

Polyclonal antisera to -amanitin were generated in sheep and used to construct a competitive ELISA for measurement of the toxin in human serum and urine. The assay had a detection limit of about 80 pg mL^–1, a dynamic range of 80–2,000 pg mL^–1, a cross reactivity of 22% with -amanitin, and no cross reactivities with cyclic peptides from algal sources. Assay responses in buffer, serum, and urine were remarkably similar. Coupling of the toxin to carrier proteins was carried out by previously unreported methods. The key step that allowed the construction of the highly sensitive assay was the introduction of a novel heterologous hapten derivative made of -amanitin-cyanuric chloride derivative. The new derivative overcame the problems of bridge binding that was, in this case, particularly serious with the homologous hapten derivative. The study demonstrated that the developed antiserum and ELISA procedure can be used to detect -amanitin and related toxins from Amanita phalloides in human serum and urine samples from suspected poison cases and enable early treatment to be administered.     

Synthese und Geruch von (E)- und (Z)-bis-homo-ß-Santalol

Summary The synthesis of the title compounds is described. Guided by theoretical considerations and molecular modeling studies, the influence of the bulky group opposite to the osmophorically important primary hydroxyl function on the odour impression is determined. The organoleptic evaluation proved the predicted sandal like odour of the (Z)-isomer and its also predicted absence with (E)-isomer. A moderate increase of the volume of the bulky group shows no influence on the sandalwood odour of the new analogue.

     

Design of a Novel Sort of Luminescent Terbium(III) Hybrid Materials with Potential Molecular Bridge

Summary. A kind of precursor molecule (abbreviated as EPDA–APMS) was synthesized by means of the amidation reaction of 5-ethylpyridine-2,3-dicarboxylic acid (EPDA) with a crosslinking molecule (3-aminopropyl)trimethoxysilane (APMS). Then the hybrid materials were obtained by reaction of this kind of monomer (EPDA–APMS), tetraethoxysilane (TEOS) and Tb(NO₃)₃·6H₂O by an in-situ sol-gel process, resulting in a novel molecular hybrid material (named as Tb–EPDA–APMS) with double chemical bonds (Tb–O coordination bond and Si–O covalent bond). Ultraviolet absorption, phosphorescence, and fluorescence spectra were applied to characterize the photophysical properties of the obtained hybrid material. The strong luminescence of Tb³⁺ substantiates optimum energy match and effective intramolecular energy transfer between the triplet state energy of modified ligand bridge and emissive energy level of Tb³⁺.     

断层泥显微特征研究在桥基稳定性评价中的应用

基于SEM研究了桥基断裂断层泥的原状显微结构和显微构造、石英碎砾的显微构造、表面刻蚀形貌和结构特征 ,并进一步分析和评价了断裂的抗震和抗断关键问题 ,其对系统论证在断裂带上建设特大型过江桥梁工程的稳定性具有重大实际意义 ,并为镇扬大桥工程的合理设计和安全运行提供了地质依据     

Experimental Testing of a Moving Force Identification Bridge Weigh-in-Motion Algorithm

Bridge weigh-in-motion systems are based on the measurement of strain on a bridge and the use of the measurements to estimate the static weights of passing traffic loads. Traditionally, commercial systems employ a static algorithm and use the bridge influence line to infer static axle weights. This paper describes the experimental testing of an algorithm based on moving force identification theory. In this approach the bridge is dynamically modeled using the finite element method and an eigenvalue reduction technique is employed to reduce the dimension of the system. The inverse problem of finding the applied forces from measured responses is then formulated as a least squares problem with Tikhonov regularization. The optimal regularization parameter is solved using the L-curve method. Finally, the static axle loads, impact factors and truck frequencies are obtained from a complete time history of the identified moving forces.     

拱北隧道灌浆加固中注浆材料室内试验研究

为保证港珠澳大桥拱北隧道灌浆加固工程安全,进行了不同加固方法的注浆材料室内研究。研究了袖阀管单液注浆中水泥品种、水灰比、早强剂的品种、抗沉剂等对水泥浆液的物理性能和固结体抗压强度的影响,研究了袖阀管双液注浆中水泥品种、水灰比、水玻璃浆液浓度、水玻璃浆液与水泥浆的体积比等固结体抗压强度的影响,研究了高压双管旋喷注浆中水泥与土的质量比、养护条件对水泥固结体的抗压强度的影响。得到的灌浆材料优化配方可满足灌浆设计要求。     

Aerodynamic control of bridge cables through shape modification: A preliminary study

This paper examines the viability of modifying bridge cable shape and surface for the purpose of controlling wind-induced vibrations. To this end, an extensive wind-tunnel test campaign was carried out on various cable shapes about the critical Reynolds number region. Cable shapes were chosen to passively modify the flow in a particular manner. Tested shapes included those which have some form of waviness, faceting and shrouding. Section models were tested using a static inclined rig, allowing them to be installed at yawed cable-wind angles for both smooth and turbulent flow conditions. The aerodynamic damping of the tested cylinders is evaluated by applying both 1- and 2-dof quasi-steady aerodynamic instability models. This allows for the prediction of regions of aerodynamic instability, as a function of flow angle and Reynolds number. Whilst the plain, wavy and faceted cylinders are predicted to suffer from either dry inclined galloping, “drag crisis” or Den Hartog galloping, the shrouded cylinder is found to be stable for all angles of attack, albeit with an increase in drag at typical design wind velocities. Finally, turbulent flow is found to introduce an increased amount of aerodynamic damping mainly by providing a more constant lift force over tested Reynolds numbers.