The preparation of nanophase tungsten carbide powder with zeolite-X catalysts

The reduction–carburization of tungsten trioxide (WO₃) under carbon monoxide flow was studied in the temperature range of 300–750 °C. The reduction–carburization of WO₃ was improved by mechanically mixing with zeolite-HX, -NaX and -KX. The interaction between cation in zeolite-X and oxygen in WO₃ affected the improvement of the reduction–carburization of WO₃ to WC. Moreover, the improved reduction–carburization of WO₃ could lead to the decrease of reaction temperature. Because the particle size of WC is in contact with a reaction temperature, the nanophase WC can be prepared at low temperature. In particular, the particle size of WC was controlled by reaction temperature. The particle sizes of produced WC at 550, 650 and 700 °C were 25, 50 and 100 nm respectively.     

Regulation of glutamatergic signalling by PACAP in the mammalian suprachiasmatic nucleus

Background  

Previous studies indicate that light information reaches the suprachiasmatic nucleus (SCN) through a subpopulation of retinal ganglion cells that contain both glutamate and pituitary adenylyl cyclase activating peptide (PACAP). While the role of glutamate in this pathway has been well studied, the involvement of PACAP and its receptors are only beginning to be understood. Speculating that PACAP may function to modulate how neurons in the suprachiasmatic nucleus respond to glutamate, we used electrophysiological and calcium imaging tools to examine possible cellular interactions between these co-transmitters.     

Characterization of mitochondria isolated from normal and ischemic hearts in rats utilizing atomic force microscopy

Mitochondria play critical roles in both the life and the death of cardiac myocytes. Various factors, such as the loss of ATP synthesis and increase of ATP hydrolysis, impairment in ionic homeostasis, formation of reactive oxygen species (ROS), and release of proapoptotic proteins are related to the generation of irreversible damage. It has been proposed that the release of cytochrome c is caused by a swelling of the mitochondrial matrix triggered by the apoptotic stimuli. However, there is a controversy about whether or not the mitochondria, indeed, swell during apoptosis. The major advantages of atomic force microscopy (AFM) over conventional optical and electron microscopes for bio-imaging include the fact that no special coating and vacuum are required and imaging can be done in all environments--air, vacuum or aqueous conditions. In addition, AFM force-distance curve measurements have become a fundamental tool in the fields of surface chemistry, biochemistry, and material science. In this study, we used AFM to observe the morphological and property changes in heart mitochondria that were isolated from a rat myocardial infarction model. From the shape parameters of the mitochondria in the AFM topographic image, it seemed that myocardial infarction caused the mitochondrial swelling. Also, the results of force-distance measurements showed that the adhesion force of heart mitochondria was significantly decreased by myocardial in infarction. Therefore, we suggested that myocardial infarction might be the cause of mitochondrial swelling and the changes in outer membrane of heart mitochondria.     

First-order transitions and thermodynamic properties in the 2D Blume-Capel model: the transfer-matrix method revisited

We investigate the first-order transition in the spin-1 two-dimensional Blume-Capel model in square lattices by revisiting the transfer-matrix method. With large strip widths increased up to the size of 18 sites, we construct the detailed phase coexistence curve which shows excellent quantitative agreement with the recent advanced Monte Carlo results. In the deep first-order area, we observe the exponential system-size scaling of the spectral gap of the transfer matrix from which linearly increasing interfacial tension is deduced with decreasing temperature. We find that the first-order signature at low temperatures is strongly pronounced with much suppressed finite-size influence in the examined thermodynamic properties of entropy, non-zero spin population, and specific heat. It turns out that the jump at the transition becomes increasingly sharp as it goes deep into the first-order area, which is in contrast to the Wang–Landau results where finite-size smoothing gets more severe at lower temperatures.     

Design of full-duplex and multifunction bidirectional CMOS transceiver for optical interconnect applications

This work presents a full-duplex and multifunction bidirectional transceiver for optical interconnect application. The transceiver utilizes a common limiting amplifier/gain stage, thus reducing total chip area and total power consumption. While providing a full-duplex bidirectional transmission with the aid of a hybrid circuit between the electrical input/output (I/O) and the optoelectronic signals from the transmitter and receiver circuits, it also allows for a half-duplex operation with the aid of a switch between the transimpedance amplifier signals and the transmitter electrical input from the I/O port. The multifunction bidirectional CMOS transceiver is designed in a 0.13 µm Si-CMOS technology, with power dissipation of 79 and 54.4 mW for the transmitter and receiver, respectively. It shows a 3-dB bandwidth of 5.58 and 5.69 GHz for the transmitter and the receiver respectively and with a 3-dB gain of 66.14 and 69.6 dB, in full-duplex mode. The transceiver operates up to 7 Gb/s in full-duplex mode.     

A strip-shield improves the efficiency of a solenoid coil in probes for high-field solid-state NMR of lossy biological samples

A strip-shield inserted between a high inductance double-tuned solenoid coil and the glass tube containing the sample improves the efficiency of probes used for high-field solid-state NMR experiments on lossy aqueous samples of proteins and other biopolymers. A strip-shield is a coil liner consisting of thin copper strips layered on a PTFE (polytetrafluoroethylene) insulator. With lossy samples, the shift in tuning frequency is smaller, the reduction in Q, and RF-induced heating are all significantly reduced when the strip-shield is present. The performance of 800 MHz ¹H/¹⁵N and ¹H/¹³C double-resonance probes is demonstrated on aqueous samples of membrane proteins in phospholipid bilayers.     

A sonochemical-assisted synthesis and annealing temperature effect of La<Subscript>0.7</Subscript>Sr<Subscript>0.3</Subscript>MnO<Subscript>3</Subscript> nanoparticles

This paper reports on the sonochemical-assisted synthesis of La_0.7Sr_0.3MnO₃ (LSMO) nanoparticles (NPs) which have a single-crystalline perovskite structure. The average particle size of LSMO NPs was controlled from about 40 to 120 nm by changing the annealing temperatures from 750 to 1050°C. The particle size, electrical resistivity, and ferromagnetic transition temperature of LSMO NPs were strongly dependent on the annealing temperature. A substantial decrease in resistivity and an enhancement in the insulator–metal transition temperature were found on increasing the annealing temperature. Furthermore, the enhancement in magnetization and paramagnetic–ferromagnetic (PM–FM) transition temperatures was observed as the annealing temperature increases.     

Signatures of the Unruh effect via high-power, short-pulse lasers

The ultra-high fields of high-power short-pulse lasers are expected to contribute to understanding fundamental properties of the quantum vacuum and quantum theory in very strong fields. For example, the neutral QED vacuum breaks down at the Schwinger field strength of 1.3×10¹⁸ V/m, where a virtual e⁺e^- pair gains its rest mass energy over a Compton wavelength and materializes as a real pair. At such an ultra-high field strength, an electron experiences an acceleration of a_S=2×10²⁸g and hence fundamental phenomena such as the long predicted Unruh effect start to play a role. The Unruh effect implies that the accelerated electron experiences the vacuum as a thermal bath with the Unruh temperature. In its accelerated frame the electron scatters photons off the thermal bath, corresponding to the emission of an entangled pair of photons in the laboratory frame. While it remains an experimental challenge to reach the critical Schwinger field strength within the immediate future even in view of the enormous thrust in high-power laser developments in recent years, the near-future laser technology may allow to probe the signatures of the Unruh effect mentioned above. Using a laser-accelerated electron beam (γ～300) and a counter-propagating laser beam acting as optical undulator should allow to create entangled Unruh photon pairs (i.e., signatures of the Unruh effect) with energies of the order of several hundred keV. An even substantially improved experimental scenario can be realized by using a brilliant 20 keV photon beam as X-ray undulator together with a low-energy (γ≈2) electron beam. In this case the separation of the Unruh photon pairs from background originating from linearly accelerated electrons (classical Larmor radiation) is significantly improved. Detection of the Unruh photons may be envisaged by Compton polarimetry in a 2D-segmented position-sensitive germanium detector.     

On 3-skein isomorphisms of graphs

It is shown that a 3-skein isomorphism between 3-connected graphs with at least 5 vertices is induced by an isomorphism. These graphs have no loops but may be infinite and have multiple edges.     

A Paper‐Based Platform for Long‐Term Deposition of Nanoparticles with Exceptional Redispersibility,Stability, and Functionality

Although nanoparticles (NPs) can be carefully engineered to have maximal stability and functionality desirable for use in diverse applications, they are generally not suitable for long‐term storage in solution. It is also difficult to store NPs in a dry state because dried NPs generally become aggregated and cannot easily be redispersed. Thus, a new strategy allowing long‐term storage of NPs with high stability, redispersibility, and functionality is highly demanded. By passivating the 13 nm gold nanoparticle (AuNP) surface with stabilizing agents and treating a paper substrate with both bovine serum albumin and sucrose after coating with a hydrophobic polyvinyl butyral layer, it is possible to fully redisperse (≈100%) dried AuNPs with colloidal stability comparable to that of as‐prepared AuNPs. Furthermore, AuNPs physically stabilized with polyvinylpyrrolidone can react with thiol‐containing compounds, such as 1,4‐dithiothreitol (DTT). Taking advantage of the oxidation reaction of hypochlorous acid with DTT, it is possible to demonstrate a paper‐based colorimetric sensor for detection of residual chlorine in water. Since this strategy is applicable to large‐sized AuNPs (30–90 nm), silver NPs, oleic acid‐capped magnetic NPs, and cetrimonium bromide‐passivated gold nanorods, it can be used for diverse NPs requiring long‐term storage for many applications.