The effects of surface finish and grain size on the strength of sintered silicon carbide

The effects of surface treatment and microstructure, especially abnormal grain growth, on the strength of sintered SiC were studied. The surfaces of sintered SiC were treated with 400, 800 and 1200 grit diamond wheels. Grain growth was induced by increasing the sintering times at 2050 C. The beta to alpha transformation occurred during the sintering of beta-phase starting materials and was often accompanied by abnormal grain growth. The overall strength distributions were established using Weibull statistics. The strength of the sintered SiC is limited by extrinsic surface flaws in normal-sintered specimens. The finer the surface finish and grain size, the higher the strength. But the strength of abnormal sintering specimens is limited by the abnormally grown large tabular grains. The Weibull modulus increases with decreasing grain size and decreasing grit size for grinding

Cerenkov Line Emission as a Possible Mechanism of X-ray Lines in Gamma-ray Bursts

The recent discoveries of X-ray lines in the afterglows of gamma-ray bursts (GRBs) provide significant clues to the nature of GRB progenitors and central environments. However, the iron line interpretation by fluorescence or recombination mechanism requires a large amount of iron material. We argue that the very strong iron line could be attributed to an alternative mechanism: Cerenkov line emission since relativistic electrons and dense medium exist near GRB sites. Therefore, the broad iron lines are expected, and line intensity will be nearly independent of the iron abundance, the medium with the anomalously high Fe abundance is not required.Comment: 4 pages, revised version accepted for the publication in ApJ

Suppression of the superconducting energy gap in intrinsic Josephson junctions of Bi2Sr2CaCu2O8+δ\mathbf{Bi_2Sr_2CaCu_2O_{8+\delta}} single crystals

We have observed back-bending structures at high bias current in the current-voltage curves of intrinsic Josephson junctions. These structures may be caused by nonequilibrium quasiparticle injection and/or Joule heating. The energy gap suppression varies considerably with temperature. Different levels of the suppression are observed when the same level of current passes through top electrodes of different sizes. Another effect which is seen and discussed, is a super-current ``reentrance'' of a single intrinsic Josephson junction with high bias current.Comment: accepted by Supercond. Sci. and Tech., 200

International intermediaries: A systematic literature review and research agenda

Intermediaries such as trading companies, agents and merchants have played a key role in international business for centuries. Despite the growing importance of understanding the phenomenon of intermediaries, there are misperceptions and confusions regarding the concept and value of intermediaries, which result in disconnected and fragmented research findings. This study – based on an analysis of 101 articles published between 1985 and 2021 – aims to synthesise the conceptual developments and provide a more integrated understanding of both sourcing and trading intermediaries whose activities extend across national borders. The findings help to pave the way for further academic research by highlighting what we currently know and do not know about intermediaries, outlining the theoretically grounded research agenda for each of the three identified themes: (1) What are intermediaries? (2) When should intermediaries be used? and (3) How do intermediaries work and develop? The study shows that despite decades of research on this topic, the literature to date has been limited and scattered. Researchers are encouraged to consider the role of intermediaries in a bigger picture where intermediated exchanges exist not only in dyadic relationships, but also in triads or even in broader webs of networks

Nonionic surfactant Brij35 effects on toluene biodegradation in a composite bead biofilter

Nonionic surfactant effects on the toluene dissolved in the water phase and biodegradation kinetic behaviors of toluene in a composite bead biofilter were investigated. The toluene dissolved in the water phase was enhanced by the addition of surfactant into aqueous solution and the enhancing effect was more pronounced in the surfactant concentration less than critical micelle concentration. For the microbial growth process, the microbial growth rate was inhibited at higher surfactant content and thedegree of inhibitive effect was more pronounced at lower inlet concentration. The microbial growth rate was inhibited at higher inlet concentration. Zero-order kinetic with the diffusion limitation could beregarded as the most adequate biochemical reaction model. For the biochemical reaction process, the biochemical reaction rate was also inhibited at higher surfactant content and the degree of inhibitiveeffect was more pronounced at lower inlet concentration. The biochemical reaction rate was also inhibited at higher inlet concentration. The maximum elimination capacity decreased with increasing surfactant content and it was in the range of 17.41 to 26.12 g C h-1 m-3 bed volume. The addition of surfactant into filter material was unfavorable for toluene degraded by the microbial

A conditional quantum phase gate between two 3-state atoms

We propose a scheme for conditional quantum logic between two 3-state atoms that share a quantum data-bus such as a single mode optical field in cavity QED systems, or a collective vibrational state of trapped ions. Making use of quantum interference, our scheme achieves successful conditional phase evolution without any real transitions of atomic internal states or populating the quantum data-bus. In addition, it only requires common addressing of the two atoms by external laser fields.Comment: 8 fig

Mesoscopic circuits with charge discreteness:quantum transmission lines

We propose a quantum Hamiltonian for a transmission line with charge discreteness. The periodic line is composed of an inductance and a capacitance per cell. In every cell the charge operator satisfies a nonlinear equation of motion because of the discreteness of the charge. In the basis of one-energy per site, the spectrum can be calculated explicitly. We consider briefly the incorporation of electrical resistance in the line.Comment: 11 pages. 0 figures. Will be published in Phys.Rev.

Development of a usability evaluation method using natural product-use motion

The present study developed and tested a new usability evaluation method which considers natural product-use motions. The proposed method measures both natural product-use motions (NMs) and actual product-use motions (AMs) for a product using an optical motion capture system and examines the usability of the product based on motion similarity (MS; %) between NMs and AMs. The proposed method was applied to a usability test of four vacuum cleaners (A, B, C, and D) with 15 participants and their MSs were compared with EMG measurements and subjective discomfort ratings. Cleaners A (44.6%) and C (44.2%) showed higher MSs than cleaners B (42.9%) and D (41.7%); the MSs mostly corresponded to the EMG measurements, which could indicate that AMs deviated from NMs may increase muscular efforts. However, the MSs were slightly different from the corresponding discomfort ratings. The proposed method demonstrated its usefulness in usability testing, but further research is needed with various products to generalize its effectiveness. ? 2016 Elsevier Ltd113Nsciessciscopu

Self-consistent models of triaxial galaxies in MOND gravity

The Bekenstein-Milgrom gravity theory with a modified Poisson equation is tested here for the existence of triaxial equilibrium solutions. Using the non-negative least square method, we show that self-consistent triaxial galaxies exist for baryonic models with a mild density cusp $\rho \sim {\Sigma \over r}$. Self-consistency is achieved for a wide range of central concentrations, $\Sigma \sim 10-1000\mathrm{M_{\odot}pc^{-2}}$, representing low-to-high surface brightness galaxies. Our results demonstrate for the first time that the orbit superposition technique is fruitful for constructing galaxy models beyond Newtonian gravity, and triaxial cuspy galaxies might exist without the help of Cold dark Matter.Comment: 19 pages, 1 table, 7 figures, Accepted for publication in Ap