Molecular dynamics study on ultrathin liquid water film sheared between platinum solid walls: liquid structure and energy and momentum transfer

Molecular dynamics simulation has been performed on a liquid film that is sheared in between solid surfaces. As a shear is given to the liquid film, a Couette-like flow is generated in the liquid and energy conversion occurs from the macroscopic flow to the thermal energy, which is discharged back to the solid walls. In such a way, momentum and thermal energy fluxes are present simultaneously. And all these thermal and fluid phenomena take place in highly nonequilibrium state where thermal energy is not distributed equally to each degree of freedom of molecular motion in the vicinities of the solid-liquid interface. In the present paper, platinum and water are employed as solid and liquid, respectively. First, the structure and orientation of water molecules in the vicinities of the solid surfaces are analyzed and how these structure and orientation are influenced by the shear is considered. Based on this result, momentum and thermal energy transfer in the vicinities of and at the solid-liquid interfaces are investigated in detail. Results are compared with those of our previous study, in which monatomic and diatomic molecules are employed as liquid.     

Cis double allylation of cyclopropenes using cyclopropylindium reagents

The successive double allylation of cyclopropenes with allylindium sesquiiodide and allyl iodide proceeded with a cis-addition mode in the presence of other organometallics (e.g. Grignard reagent, cuprate, Et(2)Zn and Et(3)Al), giving the corresponding cis-diallylcyclopropanes in high yields.     

Heat conduction in chain polymer liquids: molecular dynamics study on the contributions of inter- and intramolecular energy transfer

In this paper, the molecular mechanisms which determine the thermal conductivity of long chain polymer liquids are discussed, based on the results observed in molecular dynamics simulations. Linear n-alkanes, which are typical polymer molecules, were chosen as the target of our studies. Non-equilibrium molecular dynamics simulations of bulk liquid n-alkanes under a constant temperature gradient were performed. Saturated liquids of n-alkanes with six different chain lengths were examined at the same reduced temperature (0.7T(c)), and the contributions of inter- and intramolecular energy transfer to heat conduction flux, which were identified as components of heat flux by the authors' previous study [J. Chem. Phys. 128, 044504 (2008)], were observed. The present study compared n-alkane liquids with various molecular lengths at the same reduced temperature and corresponding saturated densities, and found that the contribution of intramolecular energy transfer to the total heat flux, relative to that of intermolecular energy transfer, increased with the molecular length. The study revealed that in long chain polymer liquids, thermal energy is mainly transferred in the space along the stiff intramolecular bonds. This finding implies a connection between anisotropic thermal conductivity and the orientation of molecules in various organized structures with long polymer molecules aligned in a certain direction, which includes confined polymer liquids and self-organized structures such as membranes of amphiphilic molecules in water.     

α-Dimethylaminomethylenation-induced Houben-Hoesch-type cyclization of cyanoacetanilides: a practical synthesis of 3-formyl-4-hydroxyquinolin-2(1H)-ones

The tandem reaction of cyanoacetanilides with triflic anhydride in DMF proceeded at room temperature to afford 3-formyl-4-hydroxyquinolin-2(1H)-ones in good to high yields. A detailed mechanistic study revealed that the tandem reaction proceeded via α-dimethylaminomethylenation, which promoted the subsequent Houben-Hoesch-type cyclization. Both α-functionalization and the cyclization steps were optimized, and a multi-gram scale synthesis of 3-formyl-4-hydroxyquinolin-2(1H)-one was achieved.     

Synthesis of biologically active (-)-dehydroiso-β-lapachone and the determination of its absolute configuration

Synthesis of dehydoriso-β-lapachone (1) in both racemic and enantioenriched forms is achieved starting from reduced naphthoquinone equivalents. As for the synthesis of enantioenriched dehydroiso-β-lapachone, introduction of the asymmetric center was carried out by catalytic asymmetric epoxidation of the unfunctionalized trisubstituted olefin using Shi epoxidation diketal catalyst. The construction of isopropenylfurano-1,2-(β)-naphthoquinone was carried out by acidic ring-opening reaction of the epoxynaphthalene and the following diammonium cerium(IV) nitrate (CAN) oxidation. The absolute configuration of naturally occurring (-)-dehydroiso-β-lapachone was finally determined as (R) by comparing the measured optical rotation value of the synthetic (R)-dehydroiso-β-lapachone.     

Sub-wavelength micromachining of silica glass by irradiation of CO<Subscript>2</Subscript> laser with Fresnel diffraction

We investigated a simple and productive micromachining method of silica glass by ablation using a TEA CO₂ laser (10.6 μm) with a spatial resolution down to sub-wavelength scale. The silica glass was irradiated by the TEA CO₂ laser light through a copper grid mask with square apertures of 20×20 μm² attached to the silica glass surface. After the irradiation, circular holes with a diameter of several μm were formed on the silica glass surface at the centers of the apertures due to the Fresnel diffraction effect. The minimum diameter of the holes was 3.4 μm. The characteristics of the micromachining are discussed based on the electric field distributions of the CO₂ laser light under the mask using a three-dimensional full-wave electromagnetic field simulation.     

Synthesis and Pharmacological Profile of a New Selective G Protein-Coupled Receptor 119 Agonist; 6-((2-Fluoro-3-(1-(3-isopropyl-1,2,4-oxadiazol-5-yl)piperidin-4-yl)propyl)amino)-2,3-dihydro-1H-inden-1-one

6-((2-Fluoro-3-(1-(3-isopropyl-1,2,4-oxadiazol-5-yl)piperidin-4-yl)propyl)amino)-2,3-dihydro-1H-inden-1-one is a potent drug-like G protein-coupled receptor 119 (GPR119) agonist. It is hoped that this compound would be instrumental in probing the pharmacological potential of GPR119 agonists.     

Effects of intermolecular vibrational coupling and liquid dynamics on the polarized Raman and two-dimensional infrared spectral profiles of liquid N,N-dimethylformamide analyzed with a time-domain computational method

A time-domain method for calculating polarized Raman and two-dimensional infrared (2D-IR) spectra that includes the effects of both the diagonal frequency modulations (of individual molecules in the system) and the off-diagonal (intermolecular) vibrational coupling is presented and applied to the case of the amide I band of liquid N,N-dimethylformamide. It is shown that the effect of the resonant off-diagonal vibrational coupling and the resulting delocalization of vibrational modes is clearly seen as the noncoincidence effect in the polarized Raman spectrum and some spectral features (especially as asymmetric intensity patterns) in the 2D-IR spectra. The type of 2D-IR spectra (concerning the polarization condition) most appropriate for observing this effect is discussed. On the basis of the agreement between the observed and calculated band profiles of the polarized Raman spectrum, the time dependence of the transient IR absorption anisotropy is also calculated. The method of evaluating the extent of delocalization of vibrational modes that is relevant to the features of these optical signals in the time and frequency domains is discussed. The nature of the molecular motions (concerning the liquid dynamics) that are effective on the diagonal frequency modulations is also examined.     

Development of Laser Ionization Mass Spectrometer for detection of unstable species in flames

Results are presented here on the detection of unstable species formed in flames using a novel Laser Ionization Mass Spectrometry (LIMS) system. The chemical species generated in atmospheric pressure flames were directly introduced into a mass spectrometer operated at high vacuum conditions using a newly developed interface, in which the ionization was induced by laser irradiation. Optimum conditions for the experimental conditions were investigated in order to obtain mass spectra with adequate signal to noise (S/N) ratios. In addition, the distribution profiles of various species in the flame was measured and visualized. The distribution of OH profiles was also measured under the same conditions using Planer Laser Induced Fluorescence (PLIF) diagnostics. The results showed that the profiles of OH distribution by LIMS were in good agreement with those obtained using PLIF diagnostics.