Mechanical Properties and Machinability of Glass Fiber-Reinforced Polyetheretherketone

Polyetheretherketone (PEEK) is a new type of special engineering plastic that has broad market potentials due to its particular microstructure and mechanical properties. However, few data can be found in the literatures devoted to the mechanical properties and machinability of PEEK, especially in the superprecision field. For the first time, the microscopic mechanical properties and machinability of glassfiber-reinforced PEEK (GF/PEEK), which is one typical derivative of pure PEEK, are studied. The nanoindentation experiment was performed to analyze the microscopic mechanical properties of GF/PEEK. The machinability was studied by single-point diamond turning (SPDT) on the GF/PEEK surface, the roughness and form accuracy of the machined surface were obtained in the following test. Experimental results indicate that GF/PEEK has good microscopic mechanical properties and machinability.Полиэфирэфиркетон новый вид специального конструкционного пластика, который благодаря особой микроструктуре и механическим свойствам имеет большие возможности выхода на рынок. Однако в литературе можно найти не так много данных, относящихся к механическим свойствам и обрабатываемости полиэфирэфиркетона, особенно в сверхточной области. Впервые проведено исследование обрабатываемости и механических свойств на микроскопическом уровне полиэфирэфиркетона, упрочненного стекловолокном, который является типичным производным чистого полиэфирэфиркетона. Выполнено наноиндентирование с целью анализа механических свойств материала на микроскопическом уровне. Обрабатываемость материала изучали с помощью одноточечной алмазной обточки по его поверхности, при испытании были получены значения шероховатости и точности формы обработанной поверхности. Экспериментальные результаты свидетельствуют о хороших механических свойствах и обрабатываемости полиэфирэфиркетона, упрочненного стекловолокном

Josephson Current in S-FIF-S Junctions: Nonmonotonic Dependence on Misorientation Angle

Spectra and spin structures of Andreev interface states in S-FIF-S junctions are investigated with emphasis on finite transparency and misorientation angle between in-plane magnetizations of ferromagnetic layers in a three-layer interface. It is demonstrated that the Josephson current in S-FIF-S quantum point contacts can exhibit a nonmonotonic dependence on the misorientation angle. The characteristic behavior takes place, if the pi-state is the equilibrium state of the junction in the particular case of parallel magnetizations.Comment: 5 pages, 4 figure

Flow-FISH analysis and isolation of clostridial strains in an anaerobic semi-solid bio-hydrogen producing system by hydrogenase gene target

By using hydrogenase gene-targeted polymerase chain reaction (PCR) and reverse transcriptase PCR (RT-PCR), the predominant clostridial hydrogenase that may have contributed to biohydrogen production in an anaerobic semi-solid fermentation system has been monitored. The results revealed that a Clostridium pasteurianum-like hydrogenase gene sequence can be detected by both PCR and RT-PCR and suggested that the bacterial strain possessing this specific hydrogenase gene was dominant in hydrogenase activity and population. Whereas another Clostridium saccharobutylicum-like hydrogenase gene can be detected only by RT-PCR and suggest that the bacterial strain possessing this specific hydrogenase gene may be less dominant in population. In this study, hydrogenase gene-targeted fluorescence in situ hybridization (FISH) and flow cytometry analysis confirmed that only 6.6% of the total eubacterial cells in a hydrogen-producing culture were detected to express the C. saccharobutylicum-like hydrogenase, whereas the eubacteria that expressed the C. pasteurianum-like hydrogenase was 25.6%. A clostridial strain M1 possessing the identical nucleotide sequences of the C. saccharobutylicum-like hydrogenase gene was then isolated and identified as Clostridium butyricum based on 16S rRNA sequence. Comparing to the original inoculum with mixed microflora, either using C. butyricum M1 as the only inoculum or co-culturing with a Bacillus thermoamylovorans isolate will guarantee an effective and even better production of hydrogen from brewery yeast waste

Hypoxia and H2O2 Dual-Sensitive Vesicles for Enhanced Glucose-Responsive Insulin Delivery

A glucose-responsive closed-loop insulin delivery system mimicking pancreas activity without long-term side effect has the potential to improve diabetic patients' health and quality of life. Here, we developed a novel glucose-responsive insulin delivery device using a painless microneedle-array patch containing insulin-loaded vesicles. Formed by self-assembly of hypoxia and H2O2 dual-sensitive diblock copolymer, the glucose-responsive polymersome-based vesicles (d-GRPs) can disassociate and subsequently release insulin triggered by H2O2 and hypoxia generated during glucose oxidation catalyzed by glucose specific enzyme. Moreover, the d-GRPs were able to eliminate the excess H2O2, which may lead to free radical-induced damage to skin tissue during the long-term usage and reduce the activity of GOx. In vivo experiments indicated that this smart insulin patch could efficiently regulate the blood glucose in the chemically induced type 1 diabetic mice for 10 h

Microneedle-array patches loaded with hypoxia-sensitive vesicles provide fast glucose-responsive insulin delivery

The past year demonstrated how developing pharmacological solutions for better ways of insulin substitution and making those drugs commercially available for patients with all forms of diabetes are becoming more and more complex issues worldwide in the light of increasing patient numbers and rising health-care costs. Meanwhile, the two first rapid-acting analogs are celebrating their 20th (insulin lispro) and 15th (insulin aspart) anniversaries of commercial approval. The discussion on the long-term safety concerns of insulin analogs has quieted down considerably and only further reassuring data regarding mitogenicity have become available lately. In 2013 the U.S. Food and Drug Administration (FDA) had requested additional cardiovascular data from a dedicated cardiovascular outcomes trial before the review of the New Drug Application for the long-acting insulin degludec could be completed. Degludec had received marketing authorization valid throughout the European Union (EU) and other countries already early 2013. In September 2015, the FDA approved Tresiba (insulin degludec injection) and Ryzodeg 70/30 (insulin degludec/insulin aspart injection) after reassuring data from the DEVOTE trial

Nonlinear ion-acoustic (IA) waves driven in a cylindrically symmetric flow

By employing a self-similar, two-fluid MHD model in a cylindrical geometry, we study the features of nonlinear ion-acoustic (IA) waves which propagate in the direction of external magnetic field lines in space plasmas. Numerical calculations not only expose the well-known three shapes of nonlinear structures (sinusoidal, sawtooth, and spiky or bipolar) which are observed by numerous satellites and simulated by models in a Cartesian geometry, but also illustrate new results, such as, two reversely propagating nonlinear waves, density dips and humps, diverging and converging electric shocks, etc. A case study on Cluster satellite data is also introduced.Comment: accepted by AS

Heat transfer enhancement in a micro-channel cooling system using cylindrical vortex generators.

Three-dimensional conjugate heat transfer under laminar flow conditions within a micro-channel is analysed numerically to explore the impact of a new design of vortex generator positioned at intervals along the base of the channel. The vortex generators are cylindrical with quarter-circle and half-circle cross sections, with variants spanning the whole width of the channel or parts of the channel. Micro-channels with Reynolds number ranging from 100 to 2300 are subjected to a uniform heat flux relevant to microelectronics cooling. To ensure the accuracy of the results, validations against previous microchannel studies were conducted and found to be in good agreement, before the new vortex generators with radii up to 400 µm were analysed. Using a thermal-hydraulic performance parameter expressed in a new way, the VGs described here are shown to offer significant potential in combatting the challenges of heat transfer in the technological drive toward lower weight/smaller volume electrical and electronic devices

A Precise Measurement of the Weak Mixing Angle in Neutrino-Nucleon Scattering

We report a precise measurement of the weak mixing angle from the ratio of neutral current to charged current inclusive cross-sections in deep-inelastic neutrino-nucleon scattering. The data were gathered at the CCFR neutrino detector in the Fermilab quadrupole-triplet neutrino beam, with neutrino energies up to 600 GeV. Using the on-shell definition, ${\rm sin ^2\theta_W} \equiv 1 - \frac{{\rm M_W} ^2}{{\rm M_Z} ^2}$, we obtain ${\rm sin ^2\theta_W} = 0.2218 \pm 0.0025 ({\rm stat.}) \pm 0.0036 ({\rm exp.\: syst.}) \pm 0.0040 ({\rm model})$.Comment: 10 pages, Nevis Preprint #1498 (Submitted to Phys. Rev. Lett.

The transition form factors for semi-leptonic weak decays of J/ψJ/\psi in QCD sum rules

Within the Standard Model, we investigate the semi-leptonic weak decays of $J/\psi$. The various form factors of $J/\psi$ transiting to a single charmed meson ($D^{(*)}_{(d,s)}$) are studied in the framework of the QCD sum rules. These form factors fully determine the rates of the weak semi-leptonic decays of $J/\psi$ and provide valuable information about the non-perturbative QCD effects. Our results indicate that the decay rate of the semi-leptonic weak decay mode $J/\psi \to D^{(*)-}_{s}+e^{+}+\nu_{e}$ is at order of $10^{-10}$.Comment: 28 pages, 6 figures, revised version to be published in Eur.Phys.J.