Multiscale geometric modeling of macromolecules II: Lagrangian representation

Geometric modeling of biomolecules plays an essential role in the conceptualization of biolmolecular structure, function, dynamics, and transport. Qualitatively, geometric modeling offers a basis for molecular visualization, which is crucial for the understanding of molecular structure and interactions. Quantitatively, geometric modeling bridges the gap between molecular information, such as that from X‐ray, NMR, and cryo‐electron microscopy, and theoretical/mathematical models, such as molecular dynamics, the Poisson–Boltzmann equation, and the Nernst–Planck equation. In this work, we present a family of variational multiscale geometric models for macromolecular systems. Our models are able to combine multiresolution geometric modeling with multiscale electrostatic modeling in a unified variational framework. We discuss a suite of techniques for molecular surface generation, molecular surface meshing, molecular volumetric meshing, and the estimation of Hadwiger's functionals. Emphasis is given to the multiresolution representations of biomolecules and the associated multiscale electrostatic analyses as well as multiresolution curvature characterizations. The resulting fine resolution representations of a biomolecular system enable the detailed analysis of solvent–solute interaction, and ion channel dynamics, whereas our coarse resolution representations highlight the compatibility of protein‐ligand bindings and possibility of protein–protein interactions. © 2013 Wiley Periodicals, Inc.     

Expanding the Synthesis Field of High-Silica Zeolites

Aluminosilicate zeolites are synthesized under hydrothermal conditions in a basic/alkaline medium in the pH range between 9 and 14. The synthesis of MFI-type zeolite in an acidic medium is presented. The critical parameter determining the zeolite formation in an acidic medium was found to be the isoelectric point (IEP) of gel particles. MFI-type zeolite was synthesized above the isoelectric point of the employed silica source, where the silica species exhibit a negative charge and the paradigm of zeolite formation based on the electrostatic interaction with the positively charged template is retained. No zeolite formation is observed below the isoelectric point of silica. The impact of aluminum on the zeolite formation is also studied. The results of this study will serve to extend the synthesis field of high silica zeolites to the acidic medium and thus open new opportunities to control the zeolite properties.     

A Fluorescent Sensor for Dual‐Channel Discrimination between Phosgene and a Nerve‐Gas Mimic

The ability to analyze highly toxic chemical warfare agents (CWAs) and related chemicals in a rapid and precise manner is essential in order to alleviate serious threats to humankind and public security caused by unexpected terrorist attacks and industrial accidents. In this investigation, we designed a o‐phenylenediamine‐pyronin linked dye that is capable of both fluorogenic and colorimetric discrimination between phosgene and the prototypical nerve‐agent mimic, diethyl chlorophosphate (DCP) in the solution or gas phase. Moreover, this dye has been used to construct a portable kit that can be employed for real‐time monitoring of DCP and phosgene in the field, both in a discriminatory manner, and in a simple and safe way.     

Synthesis and photocatalytic properties of highly crystalline and ordered mesoporous TiO2 thin films

Highly crystalline and ordered mesoporous TiO2 thin films have been synthesized by stabilization of the mesostructure with confined carbon; the films exhibit 2.5% photoconversion efficiency for the water photolysis at zero-bias and Xe lamp illumination of 40 mW cm(-2).     

EPR,ENDOR and DFT study of l-lysine·HCl·2H2O single crystals X-irradiated at 66 K

Electron Paramagnetic Resonance (EPR), Electron-Nuclear DOuble Resonance (ENDOR) and ENDOR-Induced EPR (EIE) results indicated at least three radicals produced in l-lysine·HCl·2H₂O crystals irradiated at 66 K. EPR from radical R1 dominated the spectra and it was identified as the carboxyl anion, (H₂OO?) CH (NH₃)⁺ (CH₂)₄ (NH₃)⁺. Density-Functional Theory (DFT) calculations supported the assignment and indicated that the carboxyl group transformed from planar to a pyramidal configuration following electron trapping. Two small couplings detected from R1 were ascribed to protons transferred to the carboxyl group from neighboring molecules through intermolecular hydrogen bonds. Radical R2 was identified as the product of decarboxylation, ?H (NH₃)⁺(CH₂)₄ (NH₃)⁺. Although it was not possible to obtain R2's α-coupling tensor from the experiment, EPR simulations and DFT calculations provided strong support for the identification. Radical R3 exhibited several β-couplings but could be detected only in one plane and could not be identified.     

妊娠晚期羊水中微量元素测定及其与胎儿生长发育关系的研究

对１０２名足月正常妊娠第一胎的产妇妊娠晚期羊水中６种微量元素（锌、铜、锰、铁、钙、镁）首次进行了测定，并通过对出生新生儿生长发育的监测探讨其与胎儿生长发育的关系。妊娠晚期羊水中６种微量元素含量（±Ｓ／×１０－５）分别为：Ｚｎ２．２９±１．７７，Ｃｕ０．１４±０．１４，Ｍｎ０．１３±０．２３，Ｆｅ３．６９±２．７０，Ｃａ８２．５４±７４．１８，Ｍｇ１８．７１±１１．０９．男女新生儿其母羊水中微量元素含量比较无显著差异，Ｐ≥０．０５．与文献报道中期妊娠羊水中所含微量元素比较有增加趋势．６种微量元素相互关系中．与锌、钙呈正相关外，锌与铜、锰、铁、镁呈负相关．低体重组与低身长组新生儿孕母羊水中锌含量明显低于高体重组和高身长组，有显著差异，Ｐ≤０．０１．铁在高身长组含量增高，与低身长组比较有显著差异，Ｐ≤０．０５．锰于低体重组含量升高，与高体重组比较有显著差异，Ｐ≤０．０１．镁与铜于低身长组含量升高，与高身长组比较有显著差异，Ｐ分别≤０．０５与０．０１．可见高铜、高锰、高镁可致胎儿生长发育迟缓．     

EPR, ENDOR, and DFT study of free radicals in L-lysine·HCl·2H2O single crystals X-irradiated at 298 K

With K-band EPR (Electron Paramagnetic Resonance), ENDOR (Electron-Nuclear DOuble Resonance), and EIE (ENDOR-induced EPR) techniques, three free radicals (RI-RIII) in L-lysine hydrochloride dihydrate single crystals X-irradiated at 298 K were detected at 298 K, and six radicals (R1, R1', R2-R5) were detected if the temperature was lowered to 66 K from 298 K. R1 and RI dominated the central portion of the EPR at 66 and 298 K, respectively, and were identified as main chain deamination radicals, (-)OOC?H(CH(2))(4)(NH(3))(+). R1' was identified as a main chain deamination radical with the different configuration from R1 at 66 K, and it probably formed during cooling the temperature from 298 to 66 K. The configurations of R1, R1', and RI were analyzed with their coupling tensors. R2 and R3 each contain one α- and four β-proton couplings and have very similar EIEs at three crystallographic axes. The two-layer ONIOM calculations (at B3LYP/6-31G(d,p):PM3) support that R2 and R3 are from different radicals: dehydrogenation at C4, (-)OOCCH(NH(3))(+)CH(2)?H(CH(2))(2)(NH(3))(+), and dehydrogenation at C5, (-)OOCCH(NH(3))(+)(CH(2))(2)?HCH(2)(NH(3))(+), respectively. The comparisons of the coupling tensors indicated that R2 (66 K) is the same radical as RII (298 K), and R3 is the same as RIII. Thus, RII and RIII also are the radicals of C4 and C5 dehydrogenation. R4 and R5 are minority radicals and were observed only when temperature was lowered to 66 K. R4 and R5 were only tentatively assigned as the side chain deamination radical, (-)OOCCH (NH(3))(+)(CH(2))(3)?H(2), and the radical dehydrogenation at C3, (-)OOCCH(NH(3))(+)?H(CH(2))(3)(NH(3))(+), respectively, although the evidence was indirect. From simulation of the EPR (B//a, 66 K), the concentrations of R1, R1', and R2-R5 were estimated as: R1, 50%; R1', 11%; R2, 14%; R3, 16%; R4, 6%; R5, 3%.     

On fail‐safe systems under random shocks

In practical situations, systems often suffer shocks from external stressing environments, stressing the system at random. These random shocks may have non‐ignorable effects on the system's reliability. In this paper, we provide sufficient (and necessary) conditions on components' lifetimes and their surviving probabilities from random shocks for comparing the lifetimes of two fail‐safe systems by means of the usual stochastic, hazard rate, and likelihood ratio orderings. Numerical examples are presented to highlight these theoretical results as well.     

Blue/green light‐emitting diode based on diethyl[N‐arylmethylenethiobenzahydrazonato]gallium complexes

Three diethylgallium complexes of type Et₂GaL [L = N‐(4‐methoxy) benzylidenethiobenzahydrazonato ( 1 ), N‐(4‐N,N‐dimethylamino)benzy lidenethiobenzahydrazonato ( 2 ) and N‐(9‐anthryl)methylenethio benzahydrazonato ( 3 )] were synthesized by the reaction of triethylgallium with appropriate N‐arylmethylenethiobenzahydrazones. The compounds obtained were characterized by elemental analysis, ¹H NMR, IR and mass spectroscopy, respectively. Monolayer light‐emitting diodes based on the diethyl[N‐arylmethylenethio benzahydrazonato]gallium doped poly(vinylcarbazole) were fabricated using a spin coating method. The photoluminescent and electroluminescent emission spectra of 1 and 3 were measured (429 and 479 nm for 1 and 3 , respectively). The electroluminescent properties of 1 and 3 were also studied. The electroluminscence bands are located in the blue/green region (465 and 510 nm for complexes 1 and 3 , respectively). Copyright © 2006 John Wiley & Sons, Ltd.     

相对滴定法的研究Ⅱ．电位滴定法测定多种弱酸的混合溶液

本实验研究了两种弱酸混合溶液中的相对滴定法。利用该法可分别检测ｐＫａ值相差１的两种弱酸混合溶液中的两种弱酸。