Synthetic studies on β-lactam antibiotics. 15. conversion of 7-epicephems into 1-oxacephems

7-Epi-1-oxacephem was obtained by stereospecific, intramolecular etherification of alcohol prepared from 7-epicephems via aldehyde or formate. Synthesis of the 3-acetoxymethyl analogwas unsuccessful. Biologically active 1-oxacephems were derived from by known processes.     

Fluorination of double-walled carbon nanotubes

Fluorine atoms are selectively attached to the sidewall of the outer shell of DWNTs without disrupting the double-layered morphology; the stoichiometry of the fluorinated DWNTs is CF(0.30).     

Metallic Ni nanoparticles confined in hexagonally ordered mesoporous silica material

Single nanometer-sized metallic Ni particles have been successfully deposited inside a hexagonally ordered mesoporous silica material by using a liquid-phase reductive deposition method.     

The reactions 6, 7Li, 9Be, 10B(e,e′p) at 700 MeV and DWIA analysis

The proton spectral functions of ⁶Li, ⁷Li, ⁹Be and ¹⁰B obtained from the (e, e′p) reactions at 700 MeV are presented. The results were analyzed in the distorted-wave impulse approximation, using the shell-model single-particle wave functions consistent with the elastic electron scattering results. The observed Ip proton momentum distributions for the nuclei ⁶Li, ⁷Li and ⁹Be show significant disagreement with the shell-model momentum distributions. The occupation probabilities of the proton single-particle states are around 0.7, with a few exceptions.     

Contact density and number of 5s electrons inβ-Sn

Lifetimes and feeding times of high spin states in ¹⁵⁶ Er have been measured employing the recoil distance method in the reaction ¹²³ Sb(³⁷ Cl,4n) at bombarding energies of 158 and 166 MeV. The yrast states up to spin 20 ? were found to be collective. These levels are fed, however, from long-lived high spin states, causing time delays up to ～ 100 ps, the existence of which is interpreted as a signature for an oblate shape at high spin.     

New measurements of Cabibbo-suppressed decays of mesons with the CLEO-c detector

Using of data collected with the CLEO-c detector, we report on first observations and measurements of Cabibbo-suppressed decays of D mesons in the following six decay modes: pi+ pi- pi0 pi0, pi+ pi+ pi- pi- pi0, pi+ pi0 pi0, pi+ pi+ pi- pi0, eta pi0, and omega pi+ pi-. Improved branching fraction measurements in eight other multipion decay modes are also presented. The measured D --> pi pi rates allow us to extract the ratio of isospin amplitudes A(DeltaI = (3/2) / A(DeltaI = (1/2)) = 0.420 +/- 0.014(stat) +/- 0.016(syst) and the strong phase shift of delta1 = (86.4 +/- 2.8 +/- 3.3) degrees, which is quite large and now more precisely determined.     

Search for exclusive multibody non- decays at the resonance

Using data collected at the psi(3770) resonance with the CLEO-c detector at the Cornell e+e- storage ring, we present searches for 25 charmless decay modes of the psi(3770), mostly multibody final states. No evidence for charmless decays is found.     

Biodegradable network elastomeric polyesters from multifunctional aliphatic carboxylic acids and poly(epsilon-caprolactone) diols

Biodegradable elastomeric network polyesters were prepared from multifunctional aliphatic carboxylic acids such as tricarballylic acid (Yt) or meso-1,2,3,4-butanetetracarboxylic acid (Xb) and poly(epsilon-caprolactone) (PCL) diols with molecular weights of 530, 1,250 and 2,000 g.mol-1. Prepolymers prepared by a melt polycondensation were cast from DMF solution and postpolymerized at 280 degrees C for various periods of times to form a network. The resultant films were transparent, flexible and insoluble in organic solvents. The network polyesters obtained were characterized by IR absorption spectra, WAXS, density measurement, DSC, and tensile test. YtPCL1250, and XbPCL1250 network polyester films showed good elastomeric properties with high ultimate elongation (540-590%), and low Young's modulus (2.5-3.3 MPa). The enzymatic degradation was estimated by the weight loss of network films in a buffer solution with Rhizopus delemar lipase at 37 degrees C. The degree and rate of degradation were significantly affected by the molecular weight of PCL diol, chemical structures of multifunctional aliphatic carboxylic acids and the morphology of network films. The changes in the solid states of network films during the degradation were also estimated by the results of DSC and WAXS. [see text]     

Development of ultra-short pulse VUV laser system for nanoscale processing

We have developed intense vacuum ultraviolet (VUV) radiation sources for advanced material processing, such as photochemical surface reactions and precise processing on a nanometer scale. We have constructed a new VUV laser system to generate sub-picosecond pulses at the wavelength of 126 nm. A seed VUV pulse was generated in Xe as the 7th harmonic of a 882-nm Ti:sapphire laser. The optimum conversion was achieved at the pressure of 1.2 Torr. The seed pulse will be amplified by the Ar₂^*\mathrm{Ar}_{2}^{*} media generated by an optical-field-induced ionization Ar plasma produced by the Ti:sapphire laser. We have obtained a gain coefficient of g=0.16 cm⁻¹. Our developing system will provide VUV ultra-short pulses with sub-μJ energy at a repetition rate of 1 kHz.