Energy Transfer from the Upper Triplet States of Aromatic Molecules

The energy transfer from the upper triplet states of diphenylamine, naphthalene and triphenylene to toluene and hexene-1 is studed. Two mechanisms of dissipation transferred energy in solvents are discussed.     

Brownian diode: Molecular motor based on a semi-permeable Brownian particle with internal potential drop

A model of an autonomous isothermal Brownian motor with an internal propulsion mechanism is considered. The motor is a Brownian particle which is semi-transparent for molecules of surrounding ideal gas. Molecular passage through the particle is controlled by a potential similar to that in the transition rate theory, i.e. characterized by two stationary states with a finite energy difference separated by a potential barrier. The internal potential drop maintains the diode-like asymmetry of molecular fluxes through the particle, which results in the particle?s stationary drift.     

Imine Derivatives of Fumaraldehyde From Oxidation of A β-Aziridinyl Alcohol

Oxidation of a β-aziridinyl alcohol with tetrapropylammonium perruthenate yields a pyrrole and two unusual imine derivatives of fumaraldehyde.     

Poly(2-(dimethylamino)ethyl methacrylate) brushes fabricated by surface-mediated RAFT polymerization and their response to pH

In this study, well-defined, high density poly(2-(dimethylamino)ethyl methacrylate) [poly(DMAEMA)] brushes were fabricated by the combination of the self-assembly of a monolayer of RAFT agent and surface-mediated RAFT polymerization. The whole fabrication process of the poly(DMAEMA) was followed by water contact angles, grazing angle-Fourier transform infrared spectroscopy, X-ray photoelectron spectroscopy, and atomic force microscopy. Kinetic studies revealed a linear increase in poly(DMAEMA) film thickness with polymerization time, indicating that the chain growth from the surface was a controlled process. Characterization of the poly(DMAEMA) brushes, such as molecular weight and thickness determination, were measured by gel permeation chromatography, and ellipsometry, and the grafting density was estimated. The pH response of the poly(DMAEMA) brushes was further investigated and the results verified the “brush-like” to “mushroom-like” transition of the poly(DMAEMA) chains due to the reversible protonation/deprotonation upon changing the solution pH.     

Normal Coordinates Analysis for The M(NH3)2+ 4 Complex Ions in D4h and Td Symmetries. Simplified Molecular Models

A normal coordinates analysis for the M(NH₃)²⁺ ₄ complex ions in T_d symmetry (M = Zn, Cd, Co) and in D_4h symmetry (M = Cu, Pd, Pt) has been undertaken on the basis of a General Valence Force Field (GVFF), using simplified molecular models. Throughout the course of the present work, we have relaxed the point mass approximation for the NH₃-ligands in order to investigate, on a quantitative basis, some relevant ligand - framework coupling vibrations. The simplest molecular model able to accomplish this purpose is to treat the ammino group, in a linear ligator approximation. We show that these model calculations provide a satisfactory set of vibrational frequencies as well as consistent sets of force constants.     

Nonequilibrium molecular dynamics simulation of coupling between nanoparticles and base-fluid in a nanofluid

The intent of this study is to examine nonequilibrium heat transfer in a copper-argon nanofluid by molecular dynamics simulation. Two different methods, the physical definition method and the curve fitting method, are introduced to calculate the coupling factor between nanoparticles and base fluid. The results show that the coupling factors obtained by these two methods are consistent. The coupling factor is proportional to the volume fraction of the nanoparticle and inversely proportional to nanoparticle diameter. In the temperature range of 90-200 K, the coupling factor is not affected by temperature. The nanoparticle aggregation results in a decrease of the coupling factor.     

Influence of the e-beam irradiation and photo-oxidation aging on the structure and properties of LDPE-OMMT nanocomposite films

In this paper two systems, polyethylene (LDPE) and polyethylene/commercial organo-modified montmorillonite (LDPE/OMMT) nanocomposite, were subjected to e-beam irradiation at different doses and both the molecular modifications and mechanical properties have been investigated through solubility, FT-IR, calorimetric and tensile tests. Moreover, in some of the irradiated systems photo-oxidation aging was performed and its effects were studied. The results show an enhancement with irradiation of the positive effect of the nano-filler loading, related to the increase of the mechanical properties, due to the increase of the nano-filler polymer interaction.Nevertheless calorimetric and FT-IR data indicate that the well known reduction of LDPE/OMMT nanocomposite resistance to photo-oxidation ageing, with respect to LDPE, is amplified by ionizing radiation.     

Three component reactions：An efficient and green synthesis of 3, 4-dihydropyrimidin-2-(1H)-ones and thiones using silica gel-supported L-pyrrolidine-2-carboxylic acid-4-hydrogen sulfate

An environmentally benign aqueous protocol for the synthesis of 3,4-dihydropyrimidin-2-(1H)-ones and thiones promoted by a green catalyst,silica gel-supported L-pyrrolidine-2-carboxylic acid-4-hydrogen sulfate,has been developed.The use of nontoxic,thermally stable and inexpensive amino acid catalyst makes the process simple with minimal amount of chemical waste.Compared with classical Biginelli reaction conditions,this new method has the advantages of high yields and simple workup procedures.     

Dissipation of the plant growth regulator hexanoic acid 2-(diethylamino) ethyl ester in pakchoi and soil

A rapid and simple method for determining the plant growth regulator hexanoic acid 2-(diethylamino) ethyl ester (DA-6) in pakchoi and soil using gas chromatography-mass spectrometry (GC-MS) has been developed. For this purpose, a single step was used to extract DA-6 with dichloromethane from aqueous-acetone extracts of vegetables and soil. Average recoveries of DA-6 in pakchoi and soil were between 85% and 104% at both spiking levels 0.01 and 0.1 mg kg^?1. Relative standard deviations (RSD) were less than 11% for all of the recovery tests. The degradation of DA-6 in pakchoi and soil was studied. The results showed that DA-6 degradation in pakchoi and soil coincided with C = 3.9903 e^{?0.0516 t} , C = 0.3476 e^{?0.0224 t} , respectively; the half-lives were 13.43 h and 30.94 h in pakchoi and soil in Beijing, respectively.     

Chiral separation and molecular simulation study of six antihistamine agents on a coated cellulose tri-(3,5-dimethylphenycarbamate) column (Chiralcel OD-RH) and its recognition mechanisms

Enantiomeric separation of six antihistamine agents was first systematically investigated on a cellulose-based chiral stationary phase (CSP), that is, cellulose tris-(3,5-dimethyl phenyl carbamate) (Chiralcel OD-RH), under the reversed-phase mode. Orphenadrine, meclizine, terfenadine, dioxopromethazine, and carbinoxamine enantiomers were completely separated under the optimized mobile phase conditions with resolutions of 5.02, 1.93, 1.68, 1.67, and 1.54, respectively. Mequitazine was partially separated with a resolution of 0.77. The influences of type and concentration of buffer salt, the pH of buffer solution, and the type and ratio of organic modifier on the chiral separation were evaluated and optimized. For a better insight into the enantiorecognition mechanisms, molecular docking was carried out via the Autodock software. The lowest binding energy and the optimal conformations of the analytes/CSP complexes were supplied, and the mechanisms of chiral recognition were determined. According to the results, the key interactions for the chiral recognition of these six analytes on CDMPC were π–π interactions, hydrophobic interactions, hydrogen bond interactions, and some special interactions.