Hydrodynamic limit of a nongradient interacting particle process

A simple example of a nongradient stochastic interacting particle system is analyzed. In this model, symmetric simple exclusion in one dimension in a periodic environment, the dynamical term in the Green-Kubo formula contributes to the bulk diffusion constant. The law of large numbers for the density field and the central limit theorem for the density fluctuation field are proven, and the Green-Kubo expression for the diffusion constant is computed exactly. The hydrodynamic equation for the model turns out to be linear.     

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Computational study of ion distributions at the air/liquid methanol interface

Molecular dynamic simulations with polarizable potentials were performed to systematically investigate the distribution of NaCl, NaBr, NaI, and SrCl(2) at the air/liquid methanol interface. The density profiles indicated that there is no substantial enhancement of anions at the interface for the NaX systems, in contrast to what was observed at the air/aqueous interface. The surfactant-like shape of the larger more polarizable halide anions, which is part of the reason they are driven to air/aqueous interfaces, was compensated by the surfactant nature of methanol itself. These halide anions had on average an induced dipole of moderate magnitude in bulk methanol. As a consequence, methanol hydroxy groups donated hydrogen bonds to anions where the negatively charged side of the anion induced dipole pointed, and methyl groups interacted with anions where the positively charged side of the anion-induced dipole pointed. Furthermore, salts were found to disrupt the surface structure of methanol. For the neat air/liquid methanol interface, there is relative enhancement of methyl groups at the outer edge of the air/liquid methanol interface in comparison with hydroxy groups, but with the addition of NaX this enhancement was reduced somewhat. Finally, with the additional of salts to methanol, the computed surface potentials decreased, which is in contrast to what is observed in corresponding aqueous systems, where the surface potential increases with the addition of salts. Both of these trends have been indirectly observed with experiments. The surface potential trends were found to be due to the greater propensity of anions for the air/water interface that is not present at the air/liquid methanol interface.     

玫瑰红与介孔二氧化硅生物光敏复合体的激发态性质

以光动力治疗药物玫瑰红( Rose Bengal,RB)与孔径为2.7nm的介孔二氧化硅MCM-41为主体材料进行结构组装,制备了具有生物光敏功能的介孔复合载体.对介孔复合载体的性质进行了表征,通过紫外吸收和荧光光谱对玫瑰红RB在介孔孔道内的光学性质进行了分析.由于介孔道表面与RB的相互作用,不同结构和性质的内孔道中的...     

Chemiluminescent Carbapenem-Based Molecular Probe for Detection of Carbapenemase Activity in Live Bacteria

Carbapenemase-producing organisms (CPOs) pose a severe threat to antibacterial treatment due to the acquisition of antibiotic resistance. This resistance can be largely attributed to the antibiotic-hydrolyzing enzymes that the bacteria produce. Current carbapenem “wonder drugs”, such as doripenem, ertapenem, meropenem, imipenem, and so on, are resistant to regular β-lactamases, but susceptible to carbapenemases. Even worse, extended exposure of bacteria to these drugs accelerates the spread of resistance genes. In order to preserve the clinical efficacy of antibacterial treatment, carbapenem drugs should be carefully regulated and deployed only in cases of a CPO infection. Early diagnosis is therefore of paramount importance. Herein, we report the design, synthesis, and activity of the first carbapenemase-sensitive chemiluminescent probe, CPCL , which may be used to monitor CPO activity. The design of our probe enables enzymatic cleavage of the carbapenem core, which is followed by a facile 1,8-elimination process and the emission of green light through rapid chemical excitation. We have demonstrated the ability of the probe to detect a number of clinically relevant carbapenemases and the successful identification of CPO present in bacterial cultures, such as those used for clinical diagnosis. We believe that our use of “turn-on” chemiluminescence activation will find significant application in future diagnostic assays and improve antibacterial treatment.