A new disilene with π-accepting groups from the reaction of disilyne RSi≡SiR (R = Si(i)Pr[CH(SiMe3)2]) with isocyanides

The reaction of 1,1,4,4-tetrakis[bis(trimethylsilyl)methyl]-1,4-diisopropyltetrasila-2-yne (1) with tert-butylisocyanide or tert-octylisocyanide produced the corresponding disilyne-isocyanide adducts [RSiSiR(CNR')(2)] (R = Si(i)Pr[CH(SiMe(3))(2)](2), R' = (t)Bu (2a) or CMe(2)CH(2)(t)Bu (2b)), which are stable below -30 °C and were characterized by spectroscopic data and, in the case of 2a, X-ray crystallography. Upon warming to room temperature, 2 underwent thermal decomposition to produce 1,2-dicyanodisilene R(NC)Si═Si(CN)R (3) and 1,2-dicyanodisilane R(NC)HSiSiH(CN)R (4) via C-N bond cleavage and elimination of an alkane and an alkene. The 1,2-dicyanodisilene derivative 3 was characterized by X-ray crystallography.     

Superior electric storage in de‐alloyed and anodic oxidized Ti–Ni–Si glassy alloy ribbons

Ti–Ni–Si glassy alloy supercapacitors, devices that store electric charge on their TiO₂ surfaces that contain many nanometer‐sized cavities, display many advantages over other power‐source technologies. The use of de‐alloying and anodic oxidization methods has made possible the synthesis of a TiO₂ surface accessible to electron trapping. Until recently, no studies have addressed the “dry” electric storage in light glassy alloys. Our device realizes AC electric storage from 193 to 453 K with a voltage variation from 10 to 150 V, and DC capacitance of ～4.8 F (～52.8 kF/cm³), on the basis of electric double layers, deep electronic trapping sites and Shottky barriers. Further gains could be attained with surface optimization.

     

Optical pump-probe scanning tunneling microscopy for probing ultrafast dynamics on the nanoscale

The development of a method for exploring the ultrafast transient dynamics in small organized structures with high spatial resolution is expected to be a basis for further advances in current science and technology. Recently, we have developed a new microscopy technique by combining scanning tunneling microscopy (STM) with ultrashort-pulse laser technology, which enables the visualization of ultrafast carrier dynamics even on the single-atomic level. A nonequilibrium carrier distribution is generated using ultrashort laser pulses and its relaxation processes are probed by STM using the optical pump-probe method realized in STM by the pulse-picking technique. In this paper, the fundamentals of the new microscopy technique are overviewed.     

Reduction of n‐type diamond contact resistance by graphite electrode

The contact resistance between heavily phosphorus doped n‐type (n⁺‐type) diamond (111) layers and graphite electrodes was investigated. To analyze the contact resistance properties in detail in the low‐voltage region, the transfer length method including nonlinear terms with a constant current was analyzed based on the double Schottky contact configuration. Using this method, we have revaluated the metal contact resistance reported previously. Using the graphite electrodes, the linearity of current‐voltage characteristics was improved. The contact resistance was reduced by a factor of ten compared to that of conventional Ti/Pt/Au electrodes. The graphite electrodes were formed directly by thermal annealing at 1300 °C for 10 min from an n⁺‐type diamond surface. (© 2014 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

Monitoring of extra-axial brain tumor response to radiotherapy using pseudo-continuous arterial spin labeling images: Preliminary results

IntroductionTechnological developments have increased the ease of performing perfusion MRI by arterial spin labeling (ASL) in clinical settings. The objective of this study was to evaluate the effects of radiotherapy on extra-axial brain tumors by using MR perfusion images obtained using the pseudo-continuous arterial spin labeling (pcASL) method.Materials and MethodsSix consecutive patients (nine lesions) with extra-axial brain tumors treated only with radiotherapy were enrolled in this study. MR examinations, including pcASL imaging, were performed before and after radiotherapy. Cerebral blood flow, maximum tumor blood flow (mTBF), tumor volume and the ratio of signal enhancement by contrast material (enhancement ratio) were evaluated in serial examinations during the course of radiotherapy. Both the percentage change in mTBF (mTBF ratio) and the percentage change in volume (volume ratio) were calculated using values obtained before and after radiotherapy. The correlation between the volume ratio and the mTBF ratio was assessed using linear regression analysis and Spearman’s rank correlation coefficient (r_s).ResultsA strong correlation was demonstrated between the tumor volume ratio and the mTBF ratio before and after radiotherapy (r_s= 0.93, P< .01). However, no significant correlation was identified between changes in enhancement and volume ratio (r_s= 0.20) or between changes in enhancement and mTBF ratio (r_s= 0.30) before and after radiotherapy.ConclusionThe mTBF measured using pcASL may serve as an additive index for tumor volume when determining tumor response to radiotherapy even in the absence of contrast material.     

Investigation of the Interaction between C60 and Si Atoms

Abstract

The interaction between C₆₀ and Si atoms was investigated using X-ray photoelectron spec-troscopy (XPS) for the photo-irradiated Si-deposited C₆₀ film in order to establish a method of a synthesis for the Si-coated C₆₀. It was found that the Cls spectrum of the photo-irradiated film contains a peak due to C-Si bonding, while no peak due to C-Si bonding was observed for the film before photo-irradiation. This indicates that Si atoms stick to C₆₀ when using the present method.     

Design,Synthesis and Physical Properties of New Liquid Crystal Materials for Active Matrix LCD (1)

Abstract

Liquid crystal materials having a decahydronaphthalene ring structure were designed for active matrix LCD and were prepared by hydrogenation of the ocatahydronaphthalenes obtained through the reaction of a fluorinated phenyl magnesium bromide with the 6-alkyl-decahydronaphthalen-2-ones and followed by dehydration. These compounds exhibit wide nematic temperature ranges with low melting points and very low birefringences. These results are useful for design of new liquid crystal mixtures for TFT-displays.     

An optical fiber cable video system

Abstract

A novel and simple approach for optimization of a multiple quantum well electroabsorption waveguide modulator is presented. In our approach, all four of the modulator characteristic parameters (on-off ratio, insertion loss, bandwidth, and driving voltage) are included. Design examples for GaAs/AlGaAs multiple quantum well modulators are presented. The accuracy of our model is confirmed by comparison between calculated and published experimental data.     

Charmonium and Meson–Molecule Hybrid Tetraquarks

In the X (3872) decay, both of the ${{J/{\psi\pi\pi}}}$ and ${{J/{\psi\pi\pi\pi}}}$ branching fractions are observed experimentally, and their sizes are comparable to each other. In order to clarify the mechanism to cause such a large isospin violation, we investigate X(3872) employing a model of coupled-channel two-meson scattering with a ${{\rm c}\bar{c}}$ core. The two-meson states consist of ${{D^0\overline{D}^{*0}}}$ , D ⁺ D ^*?, ${{J/{\psi\rho}}}$ , and ${{J/{\psi\omega}}}$ . The effects of the ρ and ω meson width are also taken into account. We calculate the transfer strength from the ${{{\rm c}\bar{c}}}$ core to the final two-meson states. It is found that very narrow ${{J/{\psi\rho}}}$ and ${{J/{\psi\omega}}}$ peaks appear very close to the ${{D^0\overline{D}^{*0}}}$ threshold for a wide range of variation in the parameter sets. The size of the ${{J/{\psi\rho}}}$ peak is almost the same as that of ${{J/{\psi\omega}}}$ , which is consistent with the experiments. The large width of the ρ meson makes the originally small isospin violation by about five times larger.     

Proton Elastic Scattering of23,25F

Proton elastic scatterings of neutron-rich nuclei ²³F and ²⁵F have been measured for the first time at 289 and 298 MeV/nucleon, respectively, using the MUST2 silicon strip detector array and RIBF facility at RIKEN. The differential cross section of ²⁵F was found to be smaller than the calculation with the global potential by Koning and Deraloche. The small cross section of ²⁵F can be well reproduced by an optical model calculation with a shallow and long-tail potential.