Hybridization-sensitive fluorescence control in the near-infrared wavelength range

A series of near-infrared fluorescent probes were designed based on the concept of emission control caused by interdye excitonic interaction. The fluorescent probes showed very weak emission in the unhybridized state, whereas they emitted near-infrared fluorescence after hybridization with the complementary nucleic acid. The hybridization-dependent switching of fluorescence emission made it possible to monitor mRNA in human cells in the range of near-infrared wavelengths.     

Arrangement of K Clusters in the K-Doped Zeolite K-LTA

Abstract

K clusters incorporated into zeolite K-LTA causes ferromagnetism below 8 K. Distribution of K⁺ ions in its α-cages was studied by X-ray powder diffraction. On the basis of space group F23, electron-density distribution was determined by Rietveld analysis followed by iteration of analysis by a maximum-entropy method and whole-pattern fitting. K⁺ ions were located in α-cages in such a way that K clusters between adjacent α-cages are not equivalent to each other, which will lead to the ferromagnetism with antiferromagnetic components.     

Synthesis and crystal structure of a layered silicate HUS-1 with a halved sodalite-cage topology

A new layered silicate, HUS-1, was synthesized by hydrothermal synthesis using decomposed FAU- and *BEA-type zeolites as nanosized silica parts. Structural analyses by X-ray powder diffractometry and solid-state magic-angle-spinning (MAS) NMR spectroscopy revealed that HUS-1 has a layered structure containing a silicate layer per unit cell along a stacking direction. Its framework topology is similar to that of SOD-type zeolites and consists of a halved sodalite cage, which includes four- and six-membered Si rings. Structure refinement by the Rietveld method showed that tetramethylammonium (TMA) ions used as a structure-directing agent (SDA) were incorporated into the interlayer. The four methyl groups of the TMA molecule were located orderly in a hemispherical cage in the silicate layer, which suggests restraint of molecular motion. The interlayer distance is estimated at about 0.15 nm, which is unusually short in comparison with that in other layered silicates (e.g., β-HLS or RUB-15) with similar framework topologies. The presence of hydrogen bonding between adjacent terminal O atoms was clearly revealed by the (1)H MAS NMR spectroscopy and by electron-density distribution obtained by the maximum entropy method.     

SYNTHESIS AND REACTIONS OF HALO DERIVATIVES OF 4-ISOPROPYL-2H-1,4-THIAZIN-3-ONE

Abstract

Reaction of 4-isopropyl-2H-1,4-thiazin-3-one 1 (R [dbnd] i-Pr) with N-chloro- and N-bromosuccinimide occurred exclusively at the 6-position to give 6-chloro and 6-bromo derivatives of 1 (R [dbnd] i-Pr), respectively, in high yield, in sharp contrast to the 2-aroyloxylation by benzoyl peroxide or m-chloroperbenzoic acid reported earlier.² Reaction of 1 (R [dbnd] i-Pr) with methanesulfonyl chloride in the presence of aluminum chloride afforded an addition compound, 4-isopropyl-5,6-dichloro-1,4-tetrahydrothiazin-3-one. The 2-chloro derivative 6 of 1 (R [dbnd] i-Pr) was successfully prepared by hydrolysis of the 2-m-chloroben-zoyloxy derivative of 1 (R [dbnd] i-Pr) followed by treatment with thionyl chloride. Derivative 6 reacted readily under mild conditions with water, alcohols, thiols, ammonia and amines to give various 2-substituted compounds of 1 (R [dbnd] i-Pr). With phenol as a nucleophile, 1 (R [dbnd] i-Pr) reacted exclusively at the para position. Reaction at carbon atoms also occurred with N,N-dimethylaniline and 2,6-xylidine.     

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.     

Structural Interpretation of Eyring Activation Parameters for Tensile Yielding Behavior of Isotactic Polypropylene Solids

The temperature and strain rate dependence of the stress-strain curves of isotactic polypropylene were analyzed on the basis of Eyring kinetic theory. The molecular and structural basis underlying the parameters, such as activation volume and activation energy, used by the Eyring analysis were studied using the lamellar cluster theory, where a stacked lamella acts as a basic structural unit under yielding and necking deformation. It was suggested that, at lower temperatures, the activation volume corresponds to chain slippage within crystalline lamellae in the lamellar clusters whereas at higher temperature the increase in activation volume results in intralamellar slip corresponding to the α₂ relaxation.     

基于BICC算法的PIV技术

对基于ＢＩＣＣ（ＢｉｎａｒｙＩｍａｇｅＣｒｏｓｓ－Ｃｏｒｒｅｌａｔｉｏｎ）算法的ＰＩＶ（ＰａｒｔｉｃｌｅＩｍａｇｅＶｅｌｏｃｉｍｅｔｒｙ）技术的原理进行了较详细的介绍．以封闭的正方形容器内的旋转流场为例，用计算机模拟检验了ＢＩＣＣ算法的可靠性，最后利用ＰＩＶ技术对阀腔内真实流场进行了测量．结果表明，ＢＩＣＣ算法能有效地进行图像粒子的识别，利用该算法可以得到精确的ＰＩＶ测量结果．     

Chlorofluorocarbons adsorption structures and energetic over faujasite type zeolites—a first principle study

Adsorption of ozone depleting chlorofluorocarbons (CFC) over zeolite is of major global environmental concern. The current communication describes first-principle calculation performed on faujasite models to investigate the nature of CFCs including fluoro, chlorofluoro and hydrofluoro/chloro carbons (CF₄, CF₃Cl, CF₂Cl₂, CFCl₃, CHF₃, CHCl₃) adsorption. Experimentally it is observed that separation of halocarbons are possible using Na–Y, though the cause is unknown. Reactivity index within the helm of Hard Soft Acid Base (HSAB) principle was used to monitor the activity of the interacting CFCs using Density Functional Theory (DFT) to propose a qualitative order. The importance of both H-bonding and cation–F/Cl interactions in determining the low-energy sorption sites were monitored and rationalized. The host guest interactions show a distinctive difference between the adsorption phenomenon between H–Y and Na–Y and as well for Cl and F. It is observed that Cl has more favorable interaction with hydrogen of H–Y compared to Na–Y and for F the situation is just reversed. To validate this trend periodic optimization calculations were performed. The interaction energy as obtained matches well with the reactivity index order resulted from cluster calculations. This study is a combination of DFT and periodic calculation to rationalize the electronic phenomenon of the interaction process.     

Detection of heterogeneity and estimation of population characteristics from the field survey data: 1987/88 Japanese feasibility study of the southern hemisphere Minke whales

To get reliable information of the age structure of whale population, Japan conducted a feasibility study of scientific research in the Antarctic in 1987/88. Though the sample was not large enough, it was the first data free from the problem of selectivity and whaling ground bias. From the analysis, it was found that the biological characteristics are highly heterogeneous spatially or other ways. Considering this, we recognize that the survey should be designed to collect the sample from the whole research area uniformly to obtain unbiased estimates of population characteristics. However, in an actual biological field survey, it is difficult to keep the sampling fractions thecisely the same for each sampling units. Therefore, it is important to detect the heterogeneity in the sample, and poststratify the data corresponding to the heterogeneity. The methodology of the estimation and model evaluation presented here will be useful for the development of biological field survey in general.