Boundary Singularity for Thermal Transpiration Problem of the Linearized Boltzmann Equation

We study the boundary singularity of the fluid velocity for the thermal transpiration problem in the kinetic theory. Logarithmic singularity has been demonstrated through the asymptotic and computational analysis. The goal of this paper is to confirm this logarithmic singularity through exact analysis. We use an iterated scheme, with the “gain” part of the collision operator as a source. The iterated scheme is appropriate for large Knudsen numbers considered here and yields an explicit leading term.     

Synthesis and assignment of the absolute stereochemistry of (+)-hemifistularin 3

The first total synthesis of the marine natural product (+)-hemifistularin 3 in enantiomerically pure form was accomplished by using the amide forming reaction of (+)-spiroisoxazoline ester with the (+)-octopamine derivative. The stereodivergent strategy employed in this effort enabled the assignment of the absolute configurations at the three stereogenic centers in (+)-hemifistularin 3.     

Dose–dependent biodistribution of prenatal exposure to rutile-type titanium dioxide nanoparticles on mouse testis

Au@TiO₂/graphene (Gr) composite with visible-light response was fabricated. The prepared samples were characterized by X-ray diffraction, X-ray photoelectron spectroscopy, transmission electron microscope, and diffuse reflection spectroscopy, respectively. The results indicated that metallic Au nanoparticles with round shape and about 10 nm in size were loaded on TiO₂ particles uniformly, and Au@TiO₂ was grafted on Gr shaped in thin and big sheets. Photocatalytic degradation of 2,4-dichlorophenol (2,4-DCP) was conducted under the visible-light irradiation (>420 nm) in order to evaluate the activity of photocatalysts. The light absorption spectrum of TiO₂ was extended to visible-light region by loading Au nanoparticles with plasmonic effect and 2,4-DCP could be degraded with Au@TiO₂ and Au@TiO₂/Gr by photocatalysis under visible light. Compared to that with Au@TiO₂, the elimination rate of 2,4-DCP was increased with Au@TiO₂/Gr. This enhanced photocatalytic performance was attributed to the concentration effect due to the improved adsorption performance introduced by Gr.     

A Study of Linear Waves Based on Extended Thermodynamics for Rarefied Polyatomic Gases

We study the dispersion relation for sound in rarefied polyatomic gases basing on the recently developed theory of extended thermodynamics (ET) for both dense and rarefied polyatomic gases. For hydrogen and deuterium gases in a wide temperature range where the rotational and vibrational modes in a molecule play a role, we compare the dispersion relations with those obtained in experiments and by the classical Navier–Stokes Fourier theory. From the comparison with experiments, we estimate the bulk viscosity and evaluate its temperature dependence. We study the characteristics of attenuation in a gas which has a larger relaxation time related to the dynamic pressure than the other relaxation times related to the shear stress and the heat flux by adopting the ET theory with 6 fields.     

SYNTHESES AND SOME PROPERTIES OF SULFOXIDES,SULFILIMINES, AMINOSULFONIUM SALTS AND SULFOXIMINES CONTAINING PYRIDINE NUCLEI

Abstract

Several 2-pyridyl sulfides (1) (e.g., methyl (1a), ethyl (1b), isopropyl (1c), benzyl (1d), 1-phenylethyl (1e), l-menthyl (If) 2-pyridyl sulfides; and bis(2-pyridylthio)methane (1g), and methyl 2-(N-oxy-pyridyl) sulfide (1h) were prepared by the usual method. Sulfoxides (2) were prepared by oxidation of the corresponding sulfides with m-chloroperbenzoic acid in good yields. A few sulfoxides were found to work as phase-transfer catalysts for some typical nucleophilic reactions in nonpolar solvents such as benzene, and in two-phase systems such as benzene-water. S-2-Pyridyl-N-(p-toluenesulfonyl) sulfilimines (3) were prepared upon treatment of sulfides with Chloramine-T. Hydrolysis of N-(p-toluenesulfonyl)-2-pyridyl-o-tolylsulfilimine (3i) with conc. sulfuric acid gave the corresponding free sulfilimine in a moderate yield. S-2-Pyridyl sulfoximines (4) were not obtained by the general method from the sulfoxides and hydrazoic acid. Alkyl-2-pyridyl sulfoximines, however, were obtained by oxidation of the free sulfilimines derived from the corresponding aminosulfonium salts (5) prepared by reaction of the sulfides with mesitylene-sulfonylhydroxylamine (MSH). These free sulfilimines and sulfoximines thus prepared were found to give adducts with a few copper salts.     

KINETICS OF THE REACTION OF SULFIMIDES WITH POTASSIUM HYDROXIDE IN METHANOL

Abstract

The reaction of sulfimides with hydroxide ion in methanol gave the corresponding sulfoxide (the solvolysis product) and/or the corresponding α-methoxysulfide (the Pummerer type product). The pseudo first order rates for the solvolysis reaction and the Pummerer type reaction were determined using a large excess of potassium hydroxide. The rates of the solvolyses are correlated with [sgrave] values and the values of ρ _X = +1.2 and ρ _Y = +0.8 were obtained for aryl methyl N-aryl-sulfonylsulfimides (p-XC₆H₄S(NSO₂C₆H₄Y-p)CH₃), and both the activation enthalpy and entropy calculated are δH≠ = 18.8 kcal mol^?1 and δS≠ = –23.9 e.u. (PhS(NSO₂C₆H₄CH₃-p)CH₃), respectively. Hammett correlation with [sgrave] values for the Pummerer type reaction gave ρz = +2.0 for N-aryl-sulfonyltetramethylenesulfimides ((CH₂)₄SNSO₂C₆H₄Z-p), and the activation enthalpy and entropy are δH≠ = 27.9 kcal mol^?1 and δS≠ = +13.3 eu ((CH₂)₄SNSO₂C₆H₄CH₃-p), respectively. All these observations suggest that the solvolysis reaction proceeds via the initial nucleophilic attack of hydroxide ion on the sulfur atom of the sulfimide namely via an S _N 2 process at the sulfur atom whereas the Pummerer type reaction proceeds by way of the E 1cb mechanism.     

STUDY OF THE MECHANISM FOR THE REARRANGEMENT OF THIOLSULFINATE WITH ACETIC ANHYDRIDE BY 13C AND 18O-TRACER EXPERIMENTS

Abstract

Recently, we found that benzyl phenylmethanethiolsulfinate (I) reacts with acetic anhydride at 60°C to afford the rearranged sulfoxide, i.e., an almost 1:1 mixture of both erythro and threo-1-(acetoxylthio)benzyl benzyl sulfoxides(II) in a substantial yield.     

A Two Phase Model for the Binding of Cations To Long-Chain Polyphosphate Anions

Abstract

Binding of uni- and divalent cations to long-chain polyphosphate anions was investigated in the presence of excess uni-univalent salt. It was concluded that the binding occurs mainly in a “territorial binding” mode, i.e., most of the bound cations move freely within a specified volume around the polymer. Intrinsic complex formation (site binding) should be expressed as an equilibrium in the polymer phase.