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91.
92.
A combined experimental and theoretical study is described which examines the influence of strain-rate and dynamic pre-strain on the ductile fracture of thin cylinders. The thin-cylinder configuration is particularly important in this case because it allows inertia terms to be directly incorporated into the theory of plastic instability. A series of quasi-static and dynamic tests is conducted on three materials with differing degrees of strain-rate sensitivity and strain-hardening. The experimental observation that fracture is inhibited at high strain-rates is in accord with the theory when inertia can no longer be considered insignificant. It is also shown that dynamic pre-strain has little or no effect on the flow stress or the strain at fracture in materials which-are essentially strain-rate insensitive, but does reduce the fracture strain in the strain-rate sensitive materials. 相似文献
93.
94.
Rajendran Satheeshkumar Werner Kaminsky Hazel A. Sparkes Karnam Jayarampillai Rajendra Prasad 《合成通讯》2013,43(19):2203-2215
A new class of pyrazolo[3,4-a]acridines have been prepared. The synthon acridones were obtained in very good yield by a one-pot reaction of 2-amino-5-chloro or nitro substituted benzophenones with 1,3-cyclic diketones in the presence of freshly prepared Eaton’s reagent without solvent, using Friedländer synthesis. The intermediates were reacted with ethylformate followed by hydrazine hydrate to afford pyrazolo[3,4-a]acridines. All of the compounds were purified by recrystallization only, and no chromatographic workup was required. The structures of the synthesized compounds were deduced by spectroscopic techniques, including single-crystal x-ray diffraction. 相似文献
95.
Dharmaraj Rajamani Rajendran Surender Arunjunairaj Mahendran Shanmugam Muthusubramanian Chinnaswamy Thangavel Vijayakumar 《Journal of Thermal Analysis and Calorimetry》2013,114(2):883-893
Silica derived from the renewable resource rice husk is modified using stearic acid and N-[4-(chlorocarbonyl)phenyl]maleimide. These materials are used as fillers in the bismaleimide, 4,4′-bismaleimidodiphenylmethane (BMIM), and thermally cured. The thermogravimetric (TG) curves for polyBMIM/silica composites showed no pronounced changes compared to the TG curve for the pure polyBMIM. Kissinger–Akahira–Sunose, Flynn–Wall–Ozawa, and Friedman methods are used to compute the activation energy (E a) for degradation. Silica and surface-modified silica using stearic acid dispersed by ultrasonication increase the activation energy for degradation and show considerable influence on the thermal stability of cured BMIM. The long alkyl chain present in the stearic acid modified silica and the bulky spacer present in the chemically modified silica definitely alter the degradation process of cured BMIM. The SEM studies indicated uniform dispersion of the silica particles in the polyBMIM. 相似文献
96.
This paper discusses the determination of calcium in wine samples using Programmable Systemon-Chip (PSoC) microcontroller. This embedded system uses a PSoC CY8C27443 integrated circuit (IC) spectrophotometer as core unit, high intensity orange LED as light source and photodiode as light detector having the relative spectral sensitivity above 93% in the range of 550–650 nm. This single-chip design reduces hardware complexity and increases the stability by miniaturizing the device. The instrument obeys Beer’s law up to the concentration of 160 mg/L. Coloring agent Methylthymol Blue (MTB) forms a complex with calcium in presence of alkali (pH ≈ 12); the complex exhibits maximum absorbance at 610 nm. The spectral range, concentration of MTB and pH of the solution at which the reaction is carried out are optimized. The results of the developed method are compared statistically with those obtained by a conventional method by applying Student’s t-test and F-test. The regression analysis reveals excellent correlation (R 2 = 0.9998) and regression line equation obtained for that line Y = 0.29 + 0.99X with standard error of 0.62. It can be concluded that the obtained results are in good agreement with the reference method at 95% confidence level. 相似文献
97.
Direct and Single‐Molecule Visualization of the Solution‐State Structures of G‐Hairpin and G‐Triplex Intermediates
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Dr. Arivazhagan Rajendran Prof. Dr. Masayuki Endo Kumi Hidaka Prof. Dr. Hiroshi Sugiyama 《Angewandte Chemie (International ed. in English)》2014,53(16):4107-4112
We present the direct and single‐molecule visualization of the in‐pathway intermediates of the G‐quadruplex folding that have been inaccessible by any experimental method employed to date. Using DNA origami as a novel tool for the structural control and high‐speed atomic force microscopy (HS‐AFM) for direct visualization, we captured images of the unprecedented solution‐state structures of a tetramolecular antiparallel and (3+1)‐type G‐quadruplex intermediates, such as G‐hairpin and G‐triplex, with nanometer precision. No such structural information was reported previously with any direct or indirect technique, solution or solid‐state, single‐molecule or bulk studies, and at any resolution. Based on our results, we proposed a folding mechanism of these G‐quadruplexes. 相似文献
98.
Thin film of poly (vinylchloride) and poly (methylmethacrylate) blend polymer electrolytes plasticized with a combination
of DBP and Li2SO4 salts have been prepared by solution casting technique. The prepared films were subjected to a.c. impedance measurements
as a function of temperature ranging from 304–373 K. The maximum conductivity at 304 K was found to be 1.24 × 10−8 S·cm−1 for PVC-PMMA-Li2SO4-DBP (7.5-17.5-5-70 mole-%). Temperature dependence studies on the ionic conductivity in the PVC-PMMA-Li2SO4-DBP system suggest that the ion conduction follows the Williams-Landel-Ferry (WLF) mechanism, which is further confirmed
by Vogel-Tamman-Fulcher (VTF) plots. XRD, FTIR, SEM and thermal studies revealed complex formation in. 相似文献
99.
Plasticizers can be used to change the mechanical and electrical properties of polymer electrolytes by reducing the degree
of crystallinity and lowering the glass transition temperature. The transport properties of gel-type ionic conducting membranes
consisting of poly(ethylene oxide) (PEO), poly(methyl methacrylate) (PMMA), LiClO4 and dioctyl phthalate, diethyl phthalate or dimethyl phthalate (DMP) are studied. The polymer films are characterized by
X-ray diffraction, Fourier transform infrared and impedance spectroscopic studies. It is found that the addition of DMP as
the plasticizer in the PEO-PMMA-LiClO4 polymer complex favours an enhancement in ionic conductivity. The maximum conductivity value obtained for the solid polymer
electrolyte film at 305 K is 3.529×10–
4 S cm–1.
Electronic Publication 相似文献
100.
The preparation and characterization of composite polymer electrolytes of PMMA-LiClO4-DMP for different concentrations of CeO2 have been investigated. FTIR studies indicate complex formation between the polymer, salt and plasticizer. The electrical conductivity values measured by a.c. impedance spectroscopy are found to depend upon the CeO2 concentration. The temperature dependence of the conductivity of the polymer films seems to obey the VTF relation. The conductivity values are presented and the results are discussed. 相似文献