Effect of Side Chain Length on Polycarboxylate Superplasticizer in Aqueous Solution: A Computational Study.

Molecular dynamics simulations were carried out to study the conformations of polycarboxylate ether (PCE) superplasticizers with different side chain lengths in aqueous solution. For four types of PCE molecules-PCE1, PCE2, PCE3, and PCE4-the steric hindrance between the PCE molecules increased with increasing side chain length. The side chain length not only affects water mobility but also affects the distribution of water molecules in the system. Simulation results indicate that water molecules were trapped by the PCE molecules, reducing the diffusion properties. PCE molecules with long side chains have more water molecules probability around the main chain and fewer water molecules probability near the side chain. Microscopic-level knowledge of the interaction between superplasticizer and water molecules facilitates understanding of the performance of superplasticizers in cement systems.

Computational Investigation into the Interactions of Traditional Chinese Medicine Molecules of WenQingYin with GluR2.

Docking and molecular dynamics simulations have been carried out to investigate the interaction of a traditional Chinese medicine, WenQingYin, with the glutamate receptor 2 (GluR2) subunit of the α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA) receptor. Four representative drug components of WenQingYin, namely 2-(3,4-dihydroxyphenyl)-5,6,7-trihydroxy-4H-chromen-4-one (PHF), 4-hydroxy-3-methoxybenzoic acid (HMB), 4-(2,3-dihydroxy-3-methylbutoxy)-7H-furo[3,2-g]chromen-7-one (DHMBP) and methyl 7-formylcyclopenta[c]pyran-4-carboxylate (cerbinal), and their complexes with GluR2 were simulated. Our results show that PHF, HMB, and DHMBP formed a partial hydrogen bond with GluR2 in its ligand-binding domain. However, cerbinal was not stable in the ligand-binding domain of GluR2 and induced a significant change in the structure of GluR2. Three-dimensional plots represent the contact and movement situation of the traditional Chinese medicine molecules in the ligand-binding domain. The combined results of the docking and molecular dynamics simulations provide insight into the interaction between these traditional Chinese medicine molecules and proteins.

Emission-tunable CuInS2/ZnS quantum dots: structure, optical properties, and application in white light-emitting diodes with high color rendering index.

Synthesis and application of CuInS2/ZnS core/shell quantum dots (QDs) with varying [Cu]/[In] ratios were conducted using a stepwise solvothermal route. CuInS2 (CIS) core QDs with varying [Cu]/[In] ratios exhibited deep-red emissions result from donor-acceptor pair recombination. The absorption and emission band gap of the CuInS2 QDs increased with the decrease in Cu content. The emission bands of the CuInS2/ZnS were tuned from 550 to 616 nm by controlling the [Cu]/[In] ratio after coating ZnS layer. The CIS QDs model was developed to elucidate the synthesized crystal structure and photoluminescence of the QDs with various [Cu]/[In] ratios. Temperature-dependent photoluminescence spectra of the CIS/ZnS QDs were also investigated. The temperature dependency of the photoluminescence energy and intensity for various CIS/ZnS QDs were studied from 25 to 200 °C. Efficient white light-emitting diodes with high color rendering index values (Ra = 90) were fabricated using CIS/ZnS QDs as color converters in combination with green light-emitting Ba2SiO4:Eu(2+) phosphors and blue light-emitting diodes.

Estimation of electron transfer properties of ferrocenyl-dicholesteryl-peptide in liquid and gel.

Molecular dynamics simulations were carried out to investigate the conformations of ferrocenyl-dicholesteryl N-formamidoformamide (Fc-LS2) molecules in solvents of methanol and 1-propanol. Fc-LS2 comprises ferrocene and cholesteryl units linked by a biocompatible N-formamidoformamide peptide unit. Our results showed that Fc-LS2 formed a gel with 1-propanol but not with methanol. Charge-transfer properties of Fc-LS2/1-propanol gel and Fc-LS2/methanol liquid were also investigated by quantum mechanical (QM) calculations. The QM results indicate that the amino acid linkages contribute to improved charge-transport properties and the transfer integrals of Fc-LS2/1-propanol are larger than those of Fc-LS2/methanol.

Spin-canting magnetization in an unusual Co4 cluster-based layer compound from a 2,3-dihydroxyquinoxaline ligand.

The self-assembly of Co(O(2)CPh)(2) with a 2,3-dihydroxyquinoxaline (H(2)dhq) linker has revealed a new two-dimensional cluster-based compound, [Co(4)(OMe)(2)(O(2)CPh)(2)(dhq)(2)(MeOH)(2)](n), which shows spin-canted magnetization and a definite magnetic hysteresis loop.

Clinical safety and anticoagulation efficacy of low-molecular-weight heparins in chronic hemodialysis patients: a single medical center experience.

BACKGROUND: In many countries low-molecular-weight heparins (LMWHs) are increasingly used for hemodialysis (HD). Low-range activated clotting time (ACT-LR) values and anti-Xa activity had been used to monitor the degree of anticoagulation caused by LMWH. However, the facilities are not easily available at most hospitals. Such data are limited in Taiwan. METHODS: A total of 76 patients receiving maintenance HD were prospectively enrolled. The HD patients were randomized to receive either nadroparin or enoxaparin and checked the ACT-LR values and anti-Xa activity. We aimed to analyze ACT-LR values and anti-Xa activity along with the clotting of the dialyzer or bleeding events associated with two LMWHs after they were administered. We also aimed to determine the dose necessary to reach maximum safety and efficacy. RESULTS: We found no significant differences in LMWH dosage, ACT-LR values, and anti-Xa activity between the two groups. There were no significant differences in bleeding/adverse events and extracorporeal circuit thrombosis between the two groups. Most of the bleeding and adverse events were subcutaneous minor bleeding. No major bleeding or mortality was found. We found significant differences in mean dosage, cost, bleeding/adverse effect, and extracorporeal circuit thrombosis between excessive and reduced nadroparin dosage groups. CONCLUSION: LMWH is not still routinely used due to its high cost in Taiwan. In our clinical experience, nadroparin and enoxaparin exhibited high levels of safety and efficacy in chronic HD patients. Reduced LMWHs dosage could promote patient's safety and decreased HD cost in HD patients with excessive dosage of LMWHs.

Slow magnetic relaxation in a cobalt magnetic chain.

A homospin ladder-like chain, [Co(Hdhq)(OAc)](n) (1; H(2)dhq = 2,3-dihydroxyquinoxaline), shows a single-chain-magnet-like (SCM-like) behavior with the characteristics of frequency dependence of the out-of-phase component in alternating current (ac) magnetic susceptibilities and hysteresis loops.

Solvent effects on molecular packing and tribological properties of octadecyltrichlorosilane films on silicon.

Self-assembled monolayer films of octadecyltrichlorosilane were prepared on silicon substrates using hexadecane, toluene, chloroform, and dichloromethane to determine the effects of solvent on molecular packing and tribological properties. Topographical atomic force microscopy images were used to evaluate the film quality and determine surface roughness, and tribological measurements, including friction, adhesion, and elasticity, provided additional information on the local nanoscale packing of the films. Our results showed that solvent viscosity and polarity affected the tribological properties of the films, with films prepared using hexadecane exhibiting superior properties. Langmuir-Blodgett experiments indicated that intermolecular interactions were stronger between octadecyltrichlorosilane and hexadecane molecules than for any other solvent in this study. These results demonstrate that solvent properties are an important consideration in monolayer film preparation and optimization for friction controlled surfaces.