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How to ensure water safety and clean water supply is a problem that cannot be ignored in modern industrialized society. However, due to the rapid urbanization, the content of heavy metal ions, antibiotics and organic pollutants in the water have increased. Water pollution has become a global problem. Therefore, how to efficiently carry out water treatment has become an urgent problem to be solved. Metal-organic frameworks (MOFs) are new porous materials with three-dimensional crystal structure, which are composed of metal ions and organic ligands. MOFs have controllable pore size, abundant adsorptive sites, a large number of active sites, so they have great application prospects in the field of water treatment. However, the water stability of general pure MOFs is relatively poor because water molecules attack the coordination bonds between metal ions and organic ligands in MOFs. Based on this theory, by modifying pure MOFs, the binding energy between metal and ligand increases, which can effectively protect the structure of MOFs. In this paper, metal ion modification, polymer modification, inorganic nonmetallic modification and functional group modification of MOFs are reviewed to remove heavy metal ions, antibiotics, and organic pollutants from water.

Abstract: A three-dimensional dynamic interaction model is developed for a LIM (linear induction motor) train and elevated bridge system, which is composed of a LIM-driven vehicle submodel and a finite element bridge submodel. Each LIM vehicle is modeled by a 27 degrees-of-freedom dynamic system. The expressions for the electromagnetic force between the linear motor and the reaction plate are derived, and the force model is established. By applying a modal superposition technique to the bridge submodel and using the measured track irregularities as the self-excitations of the train-bridge system, the equations of motion are established for analyzing the dynamic responses of the LIM vehicle and the elevated bridge. The proposed framework is applied to a 3-span elevated bridge with 29.9 m simply-supported girders. The full histories of the LIM train traversing the bridge are simulated, from which the dynamic responses of the LIM vehicle and elevated bridge system are obtained. The proposed method may help to find a way to assess the dynamic properties of elevated bridges and the running safety of a LIM train with reasonable computational effort.

An efficient in vitroplant regeneration system via hypocotyl segments of tetraploid Isatis indigoticaFort. was established. Murashige and Skoog's (MS) and Gamborg's (GB5) media were found to be superior to White medium for promoting shoot regeneration. The highest shoot regeneration (92 %) was achieved from hypocotyls cultured on MS medium containing 8.9 μM benzyladenine (BA) and 2.7 μM naphthaleneacetic acid (NAA), with an average of 4.2 shoots developed per explant. Plant regeneration was also improved when the explants were cultured in MS basal medium containing 3 % (m/v) sucrose and grown under a 12-h photoperiod. The developed shoots were well rooted in a half-strength MS medium supplemented with 0.5 μM indole-3-butyric acid (IBA) and were morphologically normal after transfer to soil.

This paper is concerned with the strength design of class 1 and class 2 steel I-beams that are curved in plan under vertical (or transverse) loading. It proposes and exemplifies straightforward lower bound interaction equations for designing steel I-beams curved in plan against combined bending and torsion actions, which are both easy to use and consistent with the corresponding methods of BS 5950 for designing steel members subjected to bending. The interaction equations incorporate the significant effects of the included angle and the secondary minor axis bending and torsion actions, and allow for different configurations of lateral bracing. The use of the proposed interaction equations will facilitate the strength design of steel I-beams curved in plan, and lead to safe and more economical structures.

In a companion paper, the effects of approximations in the flexural-torsional stability analysis of beams was studied, and it was shown that a second-order rotation matrix was sufficiently accurate for a flexural-torsional stability analysis. However, the second-order rotation matrix is not necessarily accurate in formulating finite element model for a 3-D non-linear analysis of thin-walled beams of open cross-section. The approximations in the second-order rotation matrix may introduce ‘self-straining’ due to superimposed rigid-body motions, which may lead to physically incorrect predictions of the 3-D non-linear behaviour of beams. In a 3-D non-linear elastic–plastic analysis, numerical integration over the cross-section is usually used to check the yield criterion and to calculate the stress increments, the stress resultants, the elastic–plastic stress–strain matrix and the tangent modulus matrix. A scheme of the arrangement of sampling points over the cross-section that is not consistent with the strain distributions may lead to incorrect predictions of the 3-D non-linear elastic–plastic behaviour of beams. This paper investigates the effects of approximations on the 3-D non-linear analysis of beams. It is found that a finite element model for 3-D non-linear analysis based on the second-order rotation matrix leads to over-stiff predictions of the flexural-torsional buckling and postbuckling response and to an overestimate of the maximum load-carrying capacities of beams in some cases. To perform a correct 3-D non-linear analysis of beams, an accurate model of the rotations must be used. A scheme of the arrangement of sampling points over the cross-section that is consistent with both the longitudinal normal and shear strain distributions is needed to predict the correct 3-D non-linear elastic–plastic behaviour of beams. Copyright © 2001 John Wiley & Sons, Ltd.

In formulating a finite element model for the flexural–torsional stability and 3-D non-linear analyses of thin-walled beams, a rotation matrix is usually used to obtain the non-linear strain–displacement relationships. Because of the coupling between displacements, twist rotations and their derivatives, the components of the rotation matrix are both lengthy and complicated. To facilitate the formulation, approximations have been used to simplify the rotation matrix. A simplified small rotation matrix is often used in the formulation of finite element models for the flexural–torsional stability analysis of thin-walled beams of open cross-section. However, the approximations in the small rotation matrix may lead to the loss of some significant terms in the stability stiffness matrix. Without these terms, a finite element line model may predict the incorrect flexural–torsional buckling load of a beam. This paper investigates the effects of approximations in the elastic flexural–torsional stability analysis of thin-walled beams, while a companion paper investigates the effects of approximations in the 3-D non-linear analysis. It is found that a finite element line model based on a small rotation matrix may predict incorrect elastic flexural–torsional buckling loads of beams. To perform a correct flexural–torsional stability analysis of thin-walled beams, modification of the model is needed, or a finite element model based on a second-order rotation matrix can be used. Copyright © 2001 John Wiley & Sons, Ltd.

The in-plane failure modes of steel arches range from the extremes of plastic collapse for stocky arches with significant bending actions to elastic buckling for slender arches in uniform compression. Between these extremes, failure involves an interaction between plastic collapse and elastic buckling which depends on the arch profile, support conditions, loading, and slenderness, and is influenced by geometrical imperfections and residual stresses.Few design codes give methods for designing steel arches against in-plane failure. The methods that are used are essentially based either on the buckling strengths of equivalent columns, or on the use of moment amplification or second-order elastic analysis and the attainment of a limiting stress. Any method based solely on elastic analysis and a limiting stress is necessarily conservative for stocky arches with negligible stability effects, since it ignores the often substantial redistributions that take place after first yield.This paper discusses the use of the method of plastic collapse analysis for the in-plane design of steel arches.

Arachidonic acid is elevated in a variety of cell types in response to extracellular stimuli, and has been hypothesized to exert at least some of its intracellular actions via activation of protein kinase C. Here we show that arachidonic acid stimulates a unique pattern of translocation of the epsilon-isoform of protein kinase C in isolated adult rat cardiac myocytes. Using western blot analysis, the majority of epsilon-protein kinase C was found in a cytosolic fraction in unstimulated cells. Treatment with 50 microM arachidonic acid caused a transient increase of epsilon-protein kinase C in a membrane fraction within 1 minute, then after 5-20 minutes most was found in a filament/nuclear fraction. Immunofluorescence and confocal microscopy of the filament fraction revealed a striated staining pattern with epsilon-protein kinase C localized near the Z-line where actin filaments are anchored and where transverse tubules are closely apposed to the myofilaments. delta-Protein kinase C, another isoform highly expressed in these cells, did not redistribute significantly in response to arachidonic acid, but in response to phorbol ester displayed a predominantly nuclear localization. Arachidonic acid also stimulated phosphorylation of the thin filament protein, troponin I, consistent with a filament localization for activated PKC. The physiological relevance of these findings was supported by the observation that 50 microM arachidonic acid promoted a 2.3-fold enhancement of myocyte twitch amplitude, an effect that was significantly blocked by the protein kinase C antagonist chelerythrine. Moreover, the onset of this physiological response correlated in time with translocation of epsilon-protein kinase C to the filaments. The results suggest that arachidonic acid initiates a redistribution of epsilon-protein kinase C to myofilament structures at or near the Z-line where this isozyme would be strategically located to regulate myofilament function and excitation-contraction coupling.

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