Preparation of an Advanced Intermediate for the Synthesis of Stable Analogues of Guanofosfocin

The synthesis of C‐mannosyl‐guanosine 23 , an advanced intermediate for the preparation of stable analogues of guanofosfocin, is described. This convergent approach features an improved Traube‐type synthesis of a 8‐substituted guanine, followed by ribosylation. NMR Studies show that the C‐mannopyranosyl moiety of 23 adopts a distorted ¹C₄ conformation while the nucleoside is predominantly syn‐oriented.     

In-focus Fourier-domain Optical Coherence Tomography by Complex Numerical Method

We introduce a numerical in-focus Fourier-domain optical coherence tomography(in-focus FD-OCT) which can measure cross-sectional images of samples with the high lateral resolution comparable with the resolution in the focal plane in overall range of measurement. In this method, the lateral resolution is enhanced by lateral signal processing of a complex OCT image obtained with FD-OCT. Quantitative evaluation of this method and application to measurement of a porcine eyeball are presented.     

Path factors in cubic graphs

Let ? be a set of connected graphs. An ?‐factor of a graph is its spanning subgraph such that each component is isomorphic to one of the members in ?. Let P_k denote the path of order k. Akiyama and Kano have conjectured that every 3‐connected cubic graph of order divisible by 3 has a {P₃}‐factor. Recently, Kaneko gave a necessary and sufficient condition for a graph to have a {P₃, P₄, P₅}‐factor. As a corollary, he proved that every cubic graph has a {P₃, P₄, P₅}‐factor. In this paper, we prove that every 2‐connected cubic graph of order at least six has a {P_k ∣ k ≥ , 6}‐factor, and hence has a {P₃, P₄}‐factor. © 2002 Wiley Periodicals, Inc. J Graph Theory 39: 188–193, 2002; DOI 10.1002/jgt.10022     

Optimization of hysteretic characteristics of damping devices based on pseudoelastic shape memory alloys

In order to develop a fundamental understanding and the feasibility of SMA devices for passive vibration control, an undamped SDOF system with a pseudoelastic SMA restoring force is investigated to find the basic relationship between the shape of the hysteresis loop of SMA elements and their performance as a damping device. The dynamic characteristics of the device are evaluated by the steady-state response at the resonance point in order to focus on the damping effect. Dynamic analysis utilizing the equivalent linearization approach results in two major findings that, to the best of the authors’ knowledge, have not yet been reported in the literature. These results which characterize the unique behavior of the SMA hysteresis include: (a) for a given excitation amplitude, the “scale” of the hysteresis loop, which is a measure of displacement and restoring force, needs to be adjusted so that the response sweeps the maximum loop but does not exceed it; (b) the ratio of the area confined within the hysteresis loop to the area of a corresponding envelope of triangular shape should be as large as possible. The results of this study would be quite useful not only as a guideline for the design of actual SMA devices, but also as a basis for the development of new autoadaptive materials in future.     

Differentiation of AB‐FUBINACA positional isomers by the abundance of product ions using electron ionization–triple quadrupole mass spectrometry

Mass spectrometric differentiation of structural isomers is important for the analysis of forensic samples. Presently, there is no mass spectrometric method for differentiating halogen positional isomers of cannabimimetic compounds. We describe here a novel and practical method for differentiating one of these compounds, N‐(1‐amino‐3‐methyl‐1‐oxobutan‐2‐yl)‐1‐(4‐fluorobenzyl)‐1H‐indazole‐3‐carboxamide (AB‐FUBINACA (para)), and its fluoro positional (ortho and meta) isomers in the phenyl ring by electron ionization–triple quadrupole mass spectrometry. It was found that the three isomers differed in the relative abundance of the ion at m/z 109 and 253 in the product ion spectra, while the detected product ions were identical. The logarithmic values of the abundance ratio of the ions at m/z 109 to 253 (ln(A₁₀₉/A₂₅₃)) were in the order meta < ortho < para and increased linearly with collision energy. The differences in abundances were attributed to differences in the dissociation reactivity between the indazole moiety and the fluorobenzyl group because of the halogen‐positional effect on the phenyl ring. Our methodology, which is based on the abundance of the product ions in mass spectra, should be applicable to determination of the structures of other newly encountered designer drugs. Copyright © 2016 John Wiley & Sons, Ltd.     

连铸板坯热轧中角部裂纹变化的研究

采用有限元方法对轧件角部横向和纵向裂纹在多道次立-平轧制过程中变形行为进行了模拟,分析了裂纹的闭合与扩展行为．结果表明:采用平立辊,裂纹很好闭合,但变形程度大,可能延伸和往轧件顶面移动,对角部横向裂纹,裂纹尖端节点往外扩散,对三角形横向和纵向裂纹,裂纹可能发生折叠;采用孔型立辊,立轧后,轧件裂纹很好地闭合,平轧后,横向和侧面纵向裂纹可能被拉开,顶面纵向裂纹闭合较好,只有三角形横向裂纹可能发生折叠．     

Flow structure of microbubble-laden turbulent channel flow measured by PIV combined with the shadow image technique

The turbulence structure of a horizontal channel flow with microbubbles is experimentally investigated using combined particle image velocimetry (PIV) in order to clarify the mechanism of drag reduction caused by microbubbles. A new system which simultaneously measures the liquid phase and the dispersed bubbles is proposed, based on a combination of particle tracking velocimetry (PTV), laser-induced fluorescence (LIF) and the shadow image technique (SIT). To accurately obtain the velocity of the liquid phase, tracer particles which overlap with the bubble shadow images are almost entirely eliminated in the post-processing. Finally, the turbulence characteristics of the flow field are presented, including measurements for both phases, and the bubble effect on the turbulence is quantified.     

Hopf Bifurcation in Viscous Incompressible Flow Down an Inclined Plane

We provide the Hopf bifurcation theorem, which guarantees the existence of time periodic solution bifurcating from the stationary flow down an inclined plane under certain assumptions on the eigenvalues of the problem obtained by linearization around the stationary flow. Since we reduce the problem to the fixed domain, the inhomogeneous terms of reduced equations and reduced boundary conditions contain the highest derivatives. To deal with these we apply the Lyapunov–Schmidt decomposition directly.     

High-speed observation of ultrahigh-speed submerged water jets

Some peculiar phenomena occur around ultrahigh-speed submerged water jets accompanied by very severe cavitation erosion. Using the flow visualization technique with a xenon flash, the water jets were carefully observed, and the spatial distributions of highly erosive impulsive pressures around the jets were measured by means of a pressure-sensitive film technique. The effects of the injection pressure and the nozzle configuration are systematically clarified. Thus, the characteristics and structures of ultrahigh-speed submerged water jets are clearly shown.     

Rapid nickel diffusion in cold-worked carbon steel at 320–450 °C

The diffusion coefficient of nickel in cold-worked carbon steel was determined with the diffusion couple method in the temperature range between 320 and 450 °C. Diffusion couple was prepared by electro-less nickel plating on the surface of a 20% cold-worked carbon steel. The growth in width of the interdiffusion zone was proportional to the square root of diffusion time to 12,000 h. The diffusion coefficient (D_Ni) of nickel in cold-worked carbon steel was determined by extrapolating the concentration-dependent interdiffusion coefficient to 0% of nickel. The temperature dependence of D_Ni is expressed by D_Ni = (4.5 + 5.7/?2.5) × 10^?11 exp (?146 ± 4 kJ mol^?1/RT) m²s^?1. The value of D_Ni at 320 °C is four orders of magnitude higher than the lattice diffusion coefficient of nickel in iron. The activation energy 146 kJ mol^?1 is 54% of the activation energy 270.4 kJ mol^?1 for lattice diffusion of nickel in the ferromagnetic state iron.