Chemiluminescence of NS radical produced by the reaction of active nitrogen with sulfur vapor and sulfur chloride

Kinetics of NS (B² Π → X²Π) emission produced by the reaction of active nitrogen with sulfur vapor or sulfur chloride (S₂Cl₂) has been studied as a function of the total pressure and of the concentrations of atomic nitrogen and sulfur. The B ²Π state of NS is selectively formed by the three-body recombination reaction of N ans S atoms, N(⁴S) + S(³P) + M →. NS(B ²Π) + M. The highest vibrational level of the B ²Π state observed is ν′ = 12, which gives a lower bound for the dissociation energy of 4.93 eV.     

7,11-epi-thyrsiferol: completion of its synthesis, evaluation of its antimitotic properties, and the further development of an SAR model

We (a) describe the completion of a total synthesis of 7,11-epi-thyrsiferol (4), (b) compare the antimitotic activities of thyrsiferol (2), Delta15,28-dehydrothyrsiferol (3), and 7,11-epi-thyrsiferol (4), (c) evaluate the synergistic behavior of the title compound and colchicine to inhibit cell proliferation, and (d) describe the results of conformational searches that provide additional insight concerning the SAR profile of the thyrsiferol family of natural products.     

Effects of polymerization method on structure and properties of thermoplastic polyurethanes

The effects of the dynamic polymerization method and temperature on the molecular aggregation structure and the mechanical and melting properties of thermoplastic polyurethanes (TPUs) were successfully clarified. TPUs were prepared from poly (ethylene adipate) glycol (M_n = 2074), 4,4′‐diphenylmethane diisocyanate and 1,4‐butanediol by the one‐shot (OS) and the prepolymer (PP) methods in bulk at dynamic polymerization temperatures ranging from 140 to 230 °C. Glass‐transition temperatures (T_gs) of the soft segment and melting points (T_ms) of the hard segment domains of OS‐TPUs increased and decreased, respectively, with increasing polymerization temperatures, but those of PP‐TPUs were almost independent of the polymerization temperature. T_gs of the soft segment and T_ms of the hard segment domains of these TPUs polymerized above 190 °C were almost the same regardless of the polymerization method. Solid‐state nuclear magnetic resonance spectroscopy (NMR) analyses of OS‐ and PP‐TPUs showed that the relative proton content of fast decay components, which corresponds to the hard segment domains, in these TPUs decreased with increasing polymerization temperatures. These results clearly show that the degree of microphase separation becomes weaker with increasing polymerization temperatures. The temperature dependence of dynamic storage modulus and loss tangent of OS‐TPUs coincided with those of PP‐TPUs at polymerization temperature above 190 °C. The apparent shear viscosity for OS‐ and PP‐TPUs polymerized above 190 °C approached a Newtonian behavior at low shear rates regardless of the polymerization method. These results indicate that TPUs polymerized at higher temperatures form almost the same molecular aggregation structures irrespective of the dynamic polymerization method. © 2007 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 45: 800–814, 2007     

Crystal Structure of Zinc(II) Complexes with 2-Ethyl-3-hydroxy-4H-pyran-4-thione and 2-Ethyl-3-hydroxy-4H-pyran-4-selenone

Crystallography Reports - Zn(II) complexes with 2-ethyl-3-hydroxy-4H-pyran-4-thione, [Zn(ehpt)2], and 2-ethyl-3-hydroxy-4H-pyran-4-selenone, [Zn(ehps)2], were synthesized and characterized by...     

Facile synthesis of urea derivatives under mild conditions

Urea derivatives were readily synthesized in good yields under quite mild conditions, i.e., at ambient pressure and room temperature by sulfur-assisted carbonylation of primary amines with carbon monoxide followed by oxidation of the resulting ammonium thiocarbamates with molecular oxygen.     

Design of a new multi‐turn ion optical system ‘IRIS’ for a time‐of‐flight mass spectrometer

A new multi‐turn ion optical system ‘IRIS’ has been designed for use with a high‐performance time‐of‐flight (TOF) mass spectrometer, which satisfies the new design concepts of time focusing and phase space stability. It has an elliptical flight path composed of four toroidal electric sectors, with a flight path length for one lap of 0.974 m. Dimensions and voltages of sector electrodes have been optimized to satisfy theoretical requirements by simulations using surface charge method. Generally, multi‐turn instruments require an injection and ejection system to inject and eject ions. On the basis of this ion optical study, we have designed an injection and ejection ion optical system, which achieves time focusing for the total system. Furthermore, we have designed novel field‐adjusting electrodes (FAEs) for the perforated sectors in the injection and ejection systems, which accurately correct the electric potential around the perforated sector's hole. We have also used simulations to evaluate mass resolving power and ion transmissions for various lap numbers or flight path lengths. Through these we have confirmed that mass resolving powers of over 100 000 can be achieved with reasonable ion transmissions for a given set of initial conditions. Usually a multi‐turn TOF mass spectrometer with a closed optic axis has mass range limitations from overtaking ions. To solve this problem, a TOF segmentation method is proposed that identifies all peaks in a TOF spectrum, including those from overtaking ions. Copyright © 2008 John Wiley & Sons, Ltd.     

Iridium-catalyzed ring cleavage reaction of cyclobutanone O-benzoyloximes providing nitriles

[reaction: see text] Iridium-catalyzed ring cleavage reaction of cyclobutanone O-benzoyloximes in the presence of 9,10-dihydroanthracene and potassium carbonate proceeds to give saturated nitriles via C-C bond fission at the sterically more hindered site.     

Far infrared reflection spectra of layered semiconductors

Far infrared reflection and Raman spectra of InSe were measured at 5, 77 and 300 K. Phonon frequencies obtained by reflection spectra were well explained by two-point phonon combination. The crystal structure of-type was confirmed at low temperature. Ion blocking analysis supported also no change of phase by temperature in this semiconductor.     

Facile synthesis of 7-10 membered rings by intramolecular condensation using dialkylcarbonate as solvent

A convenient large-scalable synthesis of 1-benzazepines 19 as an important intermediate of CCR5 antagonist, oral HIV-1 therapy, was established. The anilination of o-halogenobenzaldehyde 9 with alkylamino-acid 16 gave o-formylaniline-acid 17. Compound 17 was esterified followed by the improved reaction using the combination of alcoholate and dialkyl carbonate in one-pot, to easily produce 19. Namely, these new processes afforded the desired product 19 in only two steps from the starting materials, as compared with the previous 10 steps. Moreover, these convenient methodologies were applied to other heterocycles to give 8-10 membered rings, such as 1-benzazocine, 1-benzazonine, and 1-benzazecine.     

Shot-noise-induced random telegraph noise in shuttle current

Random telegraph noise in the electric current produced by shot noise is predicted for an array of movable colloid particles by Monte Carlo and molecular dynamics calculations. The electron transport is attributed to the shuttle mechanism where moving colloid particles carry charges. The colloid-particle motion induced by the source-drain voltage shows periodic and/or quasiperiodic vibrations, and the current value depends on the vibration modes. Shot noise that is uncorrelated with the colloid-particle motion causes transitions between the periodic and quasiperiodic vibration modes, resulting in random switching between the current levels corresponding to the vibration modes.