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Ferromagnetic layered structure has been made at sub-surface of the antiferromagnetic FeRh bulk samples by high energy He ion beam irradiation. In accordance with the Transport of Ions in Matter simulation, such ion beam can effectively deposit the elastic collision energy in several lm regions in the depth from the surface. Measurement with a superconducting quantum interference device reveals the irradiated samples to be ferromagnetic. Assuming that only the part the energy deposited can be modified to be ferromagnetic, the corresponding irradiation induced magnetization is consistent with the data that we previously reported. On the other hand, the X-ray magnetic circular dichroism (XMCD) spectra for the irradiated samples are totally unchanged as those for the unirradiated samples. Since XMCD signal in total emission yield method is considered to be surface sensitive with a typical probing depth of several nm, the surface magnetic state is maintained to be antiferromagnetic. By utilizing these phenomena, three-dimensional magnetic patterning of FeRh can be realized, which may potentially be used for future magnetic exchange device application such as nano-scale sensors and memories. [ABSTRACT FROM AUTHOR]

One of the challenges of multi-recycled Pu, to be used to produce MOx fuel, lies in its isotopic composition. Further recycling enriches the isotopy toward 238Pu, 240Pu, and 241Pu, which have much higher specific activities than the 239Pu isotope, meaning that those fuels are subjected to strong self-irradiation, provoking defect accumulation in the (U,Pu)O2 crystal lattice. A combination of three different techniques, XRD, EPMA, and RS (x-ray diffraction, electron probe micro-analysis, and Raman spectroscopy, respectively) was implemented to characterize a particular self-irradiated, 238Pu, 240Pu, and 241Pu-enriched MIMAS (MIcronized-MASter blend)-type MOx fuel sample, which had been stored for 15 years at room temperature under an inert atmosphere, to maximize irradiation effects. For comparison purposes, a specimen from the same batch was submitted to a thermal treatment and was completely analyzed in the two months following this treatment. Two of these methods (EPMA and RS) were used in their imaging mode. In particular, four spectral characteristics could be extracted from the Raman spectra. However, because of the inherent heterogeneity of this particular MOx material, the results had to be analyzed in part in a rather statistical way. This combination of techniques first allowed for determining the local Pu content. Then, the effects of self-irradiation were analyzed in terms of lattice parameter swelling, defect injection, and resonant scattering. The merits and uncertainties associated with these methods are discussed in terms of macro- and/or micro-strains. Finally, the Raman spectroscopy of (U,Pu)O2, in the 0%–40% range, was revisited in part, in an indirect way, however. [ABSTRACT FROM AUTHOR]

Temperature-dependent acoustic loss Q−1 is studied in partially disordered langasite (LGS, La3Ga5SiO14) and ordered catangasite (CTGS, Ca3TaGa3Si2O14) crystals and compared with previously reported CTGS and langatate (LGT, La3Ga5.5Ta0.5O14) data. Two independent techniques, a contactless tone-burst excitation technique and contacting resonant piezoelectric spectroscopy, are used in this study. Contributions to the measured Q−1(T) are determined through fitting to physics-based functions, and the extracted fit parameters, including the activation energies of the processes, are discussed. It is shown that losses in LGS and CTGS are caused by a superposition of several mechanisms, including intrinsic phonon–phonon loss, point-defect relaxations, and conductivity-related relaxations. [ABSTRACT FROM AUTHOR]

Computer simulations and machine learning provide complementary ways of identifying structure/property relationships that are typically targeting toward predicting the ideal singular structure to maximize the performance in a given application. This can be inconsistent with experimental observations that measure the collective properties of entire samples of structures that contain distributions or mixture of structures, even when synthesized and processed with care. Metallic nanoparticle catalysts are an important example. In this study, we have used a multi-stage machine learning workflow to identify the correct structure/property relationships of Pt nanoparticles relevant to oxygen reduction, hydrogen oxidation, and hydrogen evolution reactions. By including classification prior to regression, we identified two distinct classes of nanoparticles and subsequently generated the class-specific models based on experimentally relevant criteria that are consistent with observations. These multi-structure/multi-property relationships, predicting properties averaged over a large sample of structures, provide a more accessible way to transfer data-driven predictions into the lab. [ABSTRACT FROM AUTHOR]

Fluctuations of state variables play a pivotal role in analyzing small signal stability of the power system due to the integration of renewable energy sources. This paper develops a theoretical analysis methodology by using the power spectral density (PSD) for capturing the frequency and amplitude of state variable fluctuations in heterogeneous power systems with stochastic excitations. The fluctuations in generation and consumption occurring simultaneously are modeled by stochastic Ornstein–Uhlenbeck processes. The PSDs of the state variable fluctuations can be analytically calculated. PSD-based quantities have been proposed to evaluate angle and frequency deviations. Moreover, a global performance metric has been presented to measure the synchronization stability and calculated using the PSDs of frequency deviations. The underlying mathematical relationship between the metric and the primary control effort mimicking the H 2 -norm performance is explained in detail. Finally, the proposed analysis methodology is numerically illustrated on the IEEE RTS-96 test case. We investigate the impact of auto-correlations of stochastic processes on stability. Our results show the metric can be an alternative quantitative index of stability. We further find that the inertia allocation does not provide significant grid stability gain under small stochastic power fluctuations. [ABSTRACT FROM AUTHOR]

We report on the temperature (T), magnetic field (μ0H), and angle (Θ, Φ) dependent resonant absorption of X-band microwaves in spinel ferrite epitaxial films subjected to two distinct states of growth strain. The polar angle (Θ) dependence of the resonance field (Hres) in films with ∼0.5% ab-plane expanded unit cell establishes a distinct perpendicular magnetic anisotropy (PMA). The anisotropy field (Han┴) for Θ = 0° increases monotonically on lowering the temperature from 300 K to 90 K following the behavior of the saturation magnetization (Ms) keeping Han┴/Ms ≈ 1. The narrow resonance linewidth (μ0ΔHres┴ = 3.7 mT at 300 K) and its negligible (±0.3 mT) variation with temperature establish the magnetic softness of these PMA films. The dependence of Hres on Θ, Φ, and T in films subjected to compressive stress shows in-plane cubic anisotropy whose strength is nonmonotonic in temperature. The ∼2.0% compression of the unit cell basal plane also appears to accentuate noncollinearity of sublattice magnetization of such films as indicated by the T-dependence of ΔHres. The thicker films with PMA display spin wave resonances whose position allows determination of the spin wave stiffness constant together with independent determination of Han┴. The resonance characteristics of the PMA films qualify them as potential candidates for frequency agile microwave devices and magnonic circuit elements. [ABSTRACT FROM AUTHOR]

Relationship between segmental relaxation and normal-mode relaxation has been studied for molten poly(butylene oxide)s having various molecular weights by broadband dielectric spectroscopy over a wide temperature (T) range. We found that T dependence of the segmental relaxation time, τs, was weaker than the normal mode time, τn, at high T(>250 K ~ Tg + 50 K), and the τn/τs ratio systematically decreased with increasing temperature. This high temperature complexity, whose mechanism has not been discussed in detail so far, was quantitatively explained by assuming the two step processes: local conformation change of polymers (elementary process) occurs first, and then the motion of a segment unit (second process) occurs. It was also found that the elementary process was strongly correlated with the experimentally observed β-relaxation. [ABSTRACT FROM AUTHOR]

Nanocrystalline sp2-boron nitride (BN) thin films have been grown for 2 and 4.5 h on mechanically polished polycrystalline pyrolytic boron nitride substrates at 1060 °C via chemical vapor deposition using diborane (B2H6) and ammonia (NH3) as the B- and N sources, respectively. The use of an N/B gas phase ratio of 200 resulted in sp2-BN thin films having a stoichiometric surface chemistry, as determined by x-ray photoelectron spectroscopy. Cross-sectional transmission electron microscopy revealed the initial growth of ∼4 nm thick partially ordered [0001] sp2-BN layers regardless of the crystallographic orientation of the sets of layers in the substrate. A transition zone then formed within the deposited films that contained randomly oriented polycrystalline grains and that culminated in the formation of protrusions. Atomic force microscopy verified an increase in roughening of the surfaces of the films with an increase in growth time and the associated thickness. [ABSTRACT FROM AUTHOR]

Optimal entrainment of limit-cycle oscillators by strong periodic inputs is studied on the basis of the phase-amplitude reduction and Floquet theory. Two methods for deriving the input waveforms that keep the system state close to the original limit cycle are proposed, which enable the use of strong inputs for entrainment. The first amplitude-feedback method uses feedback control to suppress deviations of the system state from the limit cycle, while the second amplitude-penalty method seeks an input waveform that does not excite large deviations from the limit cycle in the feedforward framework. Optimal entrainment of the van der Pol and Willamowski–Rössler oscillators with real or complex Floquet exponents is analyzed as examples. It is demonstrated that the proposed methods can achieve considerably faster entrainment and provide wider entrainment ranges than the conventional method that relies only on phase reduction. [ABSTRACT FROM AUTHOR]

The magnetic and dielectric polarization properties of the single crystal samples of CuFe1-xGaxO2 (x=0 and 0.02) are investigated. Experimental results show that the magnetization and dielectric polarizations are anisotropy and coupled together. Compared with pure CuFeO2, in the case with the magnetic field parallel to the c axis, a field-induced phase transition with a hysteresis is clearly observed between the five-sublattice (5SL) and three-sublattice (3SL) phases. Specially, an obvious spontaneous dielectric polarization is observed in CuFe0.98Ga0.02O2 in a lower magnetic field region, indicating that the Ga doping has an effect on the enhancement of spontaneous dielectric polarization. Based on the dilution effect, change of exchange interaction, and partial release of the spin frustration due to the structural modulation of the Ga ion dopant, the origin of the magnetization, and spontaneous polarization characteristics are discussed and the complete dielectric polarization diagrams are assumed. [ABSTRACT FROM AUTHOR]

It is expected to develop the measurement system to obtain physical/chemical information with nanoscale space resolution related to the non-thermal equilibrium phenomena. In this study, we developed controlled temperature-gradient kelvin force microscopy (T-KFM) to measure the temperature difference (ΔT)-induced vacuum level variation under non-thermal equilibrium. Therein, the biggest issue, difficulty in applying the large ΔT in narrow space (∼100 μm), was solved by introducing "heating and cooling systems" in T-KFM; one sample side is heated using a ceramic heater and the other side is cooled using liquid nitrogen. Using T-KFM, the space distribution of ΔT-induced vacuum level variation was well observed on the scale of hundreds of nanometers in a polycrystalline ZnO film with nanostructures. The obtained image of the ΔT-induced vacuum level variation can reflect a distribution of the thermal properties such as the thermal resistance and thermoelectromotive force. This pronounced technique for obtaining surface potential under T-gradient helps us to comprehend the non-thermal equilibrium phenomena. [ABSTRACT FROM AUTHOR]

Epitaxial rhombohedral boron nitride (r-BN) films were deposited on ZrB2(0001)/4H-SiC(0001) by chemical vapor deposition at 1485 °C from the reaction of triethylboron and ammonia and with a minute amount of silane (SiH4). X-ray diffraction (XRD) φ-scans yield the epitaxial relationships of r - BN (0001) ∥ Zr B 2 (0001) out-of-plane and r - BN [ 11 2 ¯ 0 ] ∥ Zr B 2 [ 11 2 ¯ 0 ] in-plane. Cross-sectional transmission electron microscopy (TEM) micrographs showed that epitaxial growth of r-BN films prevails to ∼10 nm. Both XRD and TEM demonstrate the formation of carbon- and nitrogen-containing cubic inclusions at the ZrB2 surface. Quantitative analysis from x-ray photoelectron spectroscopy of the r-BN films shows B/N ratios between 1.30 and 1.20 and an O content of 3–4 at. %. Plan-view scanning electron microscopy images reveal a surface morphology where an amorphous material comprising B, C, and N is surrounding the epitaxial twinned r-BN crystals. [ABSTRACT FROM AUTHOR]

An improved quartz crystal microbalance measurement method is described, which allows us to determine erosion, implantation, and release rates of thin films, during changing temperatures and up to 700 K. A quasi-simultaneous excitation of two eigenmodes of the quartz resonator is able to compensate for frequency drifts due to temperature changes. The necessary electronics, the controlling behavior, and the dual-mode temperature compensation are described. With this improved technique, quantitative in situ temperature-programmed desorption measurements are possible and the quartz crystal microbalance can be used for quantification of thermal desorption spectroscopy measurements with a quadrupole mass spectrometer. This is demonstrated by a study of the retention and release behavior of hydrogen isotopes in fusion-relevant materials. We find that more than 90% of the deuterium implanted into a thin film of beryllium is released during a subsequent temperature ramp up to 500 K. [ABSTRACT FROM AUTHOR]

A laser-ignited solid-propellant-fed magnetoplasmadynamic thruster (LISMPDT) is developed and tested. In this kind of thruster, a solid propellant is placed in a hollow cathode tube. When it works, the propellant is ablated and partially ionized by the laser; then, the plasma flow enters the chamber and is accelerated by the electromagnetic interaction. Unlike the typical magnetoplasmadynamic thrusters, almost any solid material can be used as a propellant in the LISMPDT; no tanks, valves, or piping systems are required for the propulsion system. Moreover, as the particles involved in the discharge process are produced from the laser ablation process, it would lead to a directed initial velocity and higher ionization. Meanwhile, a part of the energy serving the thruster could also be derived from the laser quasi as an add-on to the discharge energy with the separation of the ignition power and the ignition power unit from the thruster system. Experiments on the discharge characteristics and thrust performances were conducted and analyzed. The results validated the feasibility of the LISMPDT, and the maximal specific impulse reached ∼780 s, while the maximal thrust efficiency was expected to be about 9% under different operating conditions. It was also found that increasing the initial discharge voltage would effectively improve the propulsion performance while a longer laser pulse width led to reduced performance. [ABSTRACT FROM AUTHOR]

The response of rock mass to engineering activities related to environment greatly depends on the scale of rock mass. Therefore, the scale dependency of rock mechanical behavior under different rock mass conditions is investigated in this research. As a crucial parameter, the volume of the block provides a fundamental understanding to define the rock mass condition and possible mechanical response. In this paper, at first, a systematic approach to calculate the block size distribution (BSD) based on the natural fracture parameters using most suitable distribution functions was established with the R language. Then, the rock mass parameters were extracted from core mapping in the depth of 1500 m–2000 m and the BSD was presented in a similar manner to soil particle size distribution. Finally, the rock mass behavior under different block sizes was investigated. The results showed that Vb25 = 3.4 dm3, Vb50 = 6.4 dm3, and Vb75 = 11.2 dm3, which were the average percentages to represent the BSD. In the research area, therefore, the fractured rock mass was dominated by minor blocks. Besides, the variation of rock mass deformation vs BSD showed that the fractured rock mass was aggravated with the decrease in the block size. The results will enhance the effect of BSD on rock mass mechanical properties. [ABSTRACT FROM AUTHOR]

There are a number of pressing problems mankind is facing today that could, at least in part, be resolved by space systems. These include capabilities for fast and far-reaching telecommunication, surveying of resources and climate, and sustaining global information networks, to name but a few. Not surprisingly, increasing efforts are now devoted to building a strong near-Earth satellite infrastructure, with plans to extend the sphere of active life to orbital space and, later, to the Moon and Mars if not further. The realization of these aspirations demands novel and more efficient means of propulsion. At present, it is not only the heavy launch systems that are fully reliant on thermodynamic principles for propulsion. Satellites and spacecraft still widely use gas-based thrusters or chemical engines as their primary means of propulsion. Nonetheless, similar to other transportation systems where the use of electrical platforms has expanded rapidly, space propulsion technologies are also experiencing a shift toward electric thrusters that do not feature the many limitations intrinsic to the thermodynamic systems. Most importantly, electric and plasma thrusters have a theoretical capacity to deliver virtually any impulse, the latter being ultimately limited by the speed of light. Rapid progress in the field driven by consolidated efforts from industry and academia has brought all-electric space systems closer to reality, yet there are still obstacles that need addressing before we can take full advantage of this promising family of propulsion technologies. In this paper, we briefly outline the most recent successes in the development of plasma-based space propulsion systems and present our view of future trends, opportunities, and challenges in this rapidly growing field. [ABSTRACT FROM AUTHOR]

Chemical sensors can be used to analyze a wide variety of environmental and biological gases and liquids and may need to be able to selectively detect a target analyte. Different methods, including gas chromatography, chemiluminescence, selected ion flow tube, and mass spectroscopy, have been used to measure biomarkers. These methods show variable results in terms of sensitivity for some applications and may not meet the requirements for a handheld biosensor. A promising sensing technology utilizes AlGaN/GaN high electron mobility transistors (HEMTs). HEMT structures have been developed for use in microwave power amplifiers due to their high two dimensional electron gas (2DEG) mobility and saturation velocity. The conducting 2DEG channel of AlGaN/GaN HEMTs is very close to the surface and extremely sensitive to adsorption of analytes. HEMT sensors can be used for detecting gases, ions, pH values, proteins, and DNA. In this paper we review recent progress on functionalizing the surface of HEMTs for specific detection of glucose, kidney marker injury molecules, prostate cancer, and other common substances of interest in the biomedical field. [ABSTRACT FROM AUTHOR]

Dual-stack phase-change recording is an option to further increase the data capacity of rewritable optical disks. Such disks consist of two recording stacks that are both recorded and read from the same side of the disk. Consequently, the first recording stack needs therefore to be semitransparent to allow recording in the second recording stack. Thick nontransparent metal layers can therefore not be used in the first recording stack, which makes the first recording stack the most challenging stack from a thermal point of view. A numerical model based on crystal growth was developed to study formation and erasure of amorphous marks in phase-change stacks that are based on fast-growth doped SbTe phase-change materials. The validity of the model was demonstrated from transmission electron microscopy analyses of recorded marks that showed a good correspondence with the calculated mark shapes in a conventional single-stack recording stack. The model was subsequently applied to analyze formation and erasure of marks in slow-cooling phase-change stacks for digital versatile disk, (DVD) and digital video recording (DVR) recording conditions. The effect of the recording velocity, the erase power, and the crystal growth velocity on the erasability of amorphous marks was simulated. The calculated phenomena are in good agreement with the phenomena observed from DVD and DVR erasability measurements. Mark formation in slow-cooling recording stacks is characterized by severe recrystallization during writing. Two possible solutions are indicated in this article, aiming at reducing the heat accumulation and the resulting recrystallization during writing of amorphous marks. Additional semitransparent heat sinks improve the mark formation considerably but also require higher write powers. Another solution is the application of modified write strategies. Modeling and recorder results are discussed for both approaches. [ABSTRACT FROM AUTHOR]

Displays have revolutionized the way we work and learn, and thus, the development of display technologies is of paramount importance. The possibility of a free-space display in which 3D graphics can be viewed from 360° without obstructions is an active area of research—holograms or lightfield displays can realize such a display, but they suffer from clipping and a limited field of view. Here, we use a phased array of ultrasonic emitters to realize a volumetric acoustophoretic display in which a millimetric particle is held in midair using acoustic radiation forces and moved rapidly along a 3D path. Synchronously, a light source illuminates the particle with the target color at each 3D position. We show that it is possible to render simple figures in real time (10 frames per second) as well as raster images at a lower frame rate. Additionally, we explore the dynamics of a fast-moving particle inside a phased-array levitator and identify potential sources of degradation in image quality. The dynamics are nonlinear and lead to distortion in the displayed images, and this distortion increases with drawing speed. The created acoustophoretic display shows promise as a future form of display technology. [ABSTRACT FROM AUTHOR]

Over the past decade, significant progress in solar forecasting has been made. Nevertheless, there are concerns about duplication, long-term value, and reproducibility; this is referred to as the "solar forecasting bubble." There is an urgent need to reconcile and improve the current solar forecasting research practice. This discussion paper proposes a so-called "ROPES" guideline that describes the desirable characteristics of future solar forecasting studies. In short, ROPES stands for reproducible, operational, probabilistic and/or physically based, ensemble, and skill. This set of characteristics is intended to facilitate comparison, comprehension, and communication within the solar forecasting field and speed up its development. Compliance with ROPES is evaluated on 79 solar forecasting references published during 2017 January to 2018 July in 6 Elsevier energy journals. Although most current papers fall short of complying with ROPES, evidence suggests that a consensus is forming. [ABSTRACT FROM AUTHOR]

Discusses a study which employed ion-assisted pulsed laser deposition to produce films containing cubic boron nitride (c-BN) films. Properties of c-BN and diamond; Mechanism of c-BN growth; Characterization of c-BN.

Focuses on a study which investigated the texture formation and development of bismuth (Bi) -based superconducting phases during the heat-treatment process. Cause of the weak-link behavior in Bi-based superconductors; Process used to create the material; Role of interfacial energy in texture formation.

Examines transport critical current and magnetization behavior in c-axis textured bismuth-lead-strontium-calcium-copper-oxygen superconductor ribbons. Importance of the densification and the thickness reduction in the superconductor by cold rolling; Use of a scanning electron microscope microstructure; Control of the nucleation event.

A new composite oxidation method combining rapid thermal oxidation (RTO) and electrochemical oxidation (ECO) is proposed to improve electron emission characteristics of electron emitters based on thick porous silicon (PS) layers. Four groups of electron emitters with 8 µm PS layers were oxidized by RTO, ECO, composite RTO–ECO, and composite ECO–RTO, respectively. The experimental results indicated greater emission current density and efficiency of electron emitters oxidized by composite oxidation versus ECO or RTO alone. The most favorable results occurred for an electron emitter oxidized by ECO–RTO, with an emission current density of 2.2 A/m2 and efficiency of 2.9%. The higher and more uniform the oxygen content in the PS layer after oxidation, the better the electron emission characteristics that the authors noted. Thick PS layers can be oxidized completely and uniformly by composite oxidation to achieve adequate oxygen content with uniform distribution. This subsequently leads to formation of a longer acceleration tunnel, which increases effective emission area and continuously speeds up electrons. [ABSTRACT FROM AUTHOR]

We developed a longitudinally excited CO2 laser with a tandem discharge tube. The tandem scheme was constituted of two 30-cm long discharge tubes connected with an intermediate electrode. Two parts, each consisting of a charged capacitance and a 30-cm long discharge tube, were electrically connected in parallel and switched by a spark gap. The tandem scheme produced a short laser pulse like that of a TEA-CO2 laser with a charging voltage of -24.8 kV, which was smaller than the -40.0 kV charging voltage of our previous CO2 laser. At a gas pressure of 3.8 kPa, the spike pulse width was 145 ns, the pulse tail length was 58.8 µs, the output energy was 52.0 mJ, and the spike pulse energy was 2.4 mJ. We also investigated the dependence of the laser pulse and the discharge voltage on gas pressure. [ABSTRACT FROM AUTHOR]

A double-fluid theory is used to find the electromagnetic wave absorption of carbon monoxide with iron-catalyzed high-pressure disproportionation (HiPco)-grown single-walled carbon nanotubes (SWNTs). The electromagnetic wave absorption of carbon monoxide with HiPco SWNTs is obtained and is studied numerically. The absorption is then deduced and their functional dependence on the number density, collision frequency, cyclotron frequency, and angle of propagation is studied. The double-fluid theory predicts that there is an electromagnetic frequency dependency on the energy absorption properties of the system under investigation. The calculation results show that effects of magnetic field strength and the angle of microwave propagation on the absorption coefficient as well as the frequency band of resonant absorption are very significant. [ABSTRACT FROM AUTHOR]

A new large radius imaging plate diffraction camera for high-resolution and high-throughput synchrotron x-ray powder diffraction by means of multiple exposures has been developed for an insertion device beamline of SPring-8, Japan. The new imaging plate camera consists of a large radius cylindrical shape imaging plate cassette that is 400 mm in length and 954.9 mm in cylinder radius. The cassette is designed to be mounted on the 2θ arm of the diffractometer of BL15XU in SPring-8. One imaging plate covers 24° and several times of exposure changing the 2θ-setting angle is necessary to obtain whole powder diffraction data up to a high angle region. One pixel of the imaging plate corresponds to 0.003° in 2θ when the readout pixel size is 50 μm squares. Separately collected data are translated to 2θ-intensity format and are connected by comparing the peak and background intensity included in the overlapped area. The exposure time is less than 120 s for most samples and the readout time is about 3 min; thus, the total measurement time for one powder diffraction pattern is less than 20 min. The measurement time is the same order as the continuous 2θ-scanning method of the third generation synchrotron powder diffractometer. The angular resolution of the new imaging plate camera was evaluated by comparing the full width at half maximum of the 111 reflection of NBS-Si. The observed angular resolution is not so high as a powder diffractometer with a Si or a Ge analyzer monochromator in the third generation synchrotron facility but higher than a powder diffractometer with a Ge analyzer monochromator at a bending magnet beamline of the second generation synchrotron. The Rietveld analysis of NBS-CeO2 was successfully carried out with the data taken by the new imaging plate camera. [ABSTRACT FROM AUTHOR]

The magnetic ordering of an easy-plane Van Vleck magnet with a large anisotropy of the easy-plane type and an antiferromagnetic exchange interaction between spins is considered in the case when the ground state of the integer-spin ions is a singlet and the antiferromagnetic phase is realized only in an external magnetic field. It is found that the phase transformation of the singlet (paramagnetic) phase to the antiferromagnetic phase is a quantum phase transition belonging to the magnetic phase transitions of the displacive type. It is shown that the Landau theory of phase transitions is applicable to such a transformation, with the order parameter being the polarization of the singlet state. Nonstandard manifestations of the paraprocess converting the second-order magnetic phase transition of the displacive type to a first-order transition are noted. The phase diagram is constructed; it differs from those of classical antiferromagnets in that the antiferromagnetic phase on it is surrounded only by the paramagnetic phase. [ABSTRACT FROM AUTHOR]

A model to describe the underlying physics of high-energy electron emission from a porous silicon diode is presented. The model is based on an atomistic tight-binding method combined with semiclassical Monte Carlo simulation. It well reproduces essential features of experimental findings. An initial acceleration region is shown to play a crucial role in generating quasiballistic electron emission. [ABSTRACT FROM AUTHOR]

Highly crystalline organic superlattice has great potential for providing innovative function in organic devices. With studies of the structure and fundamental electronical properties, we have demonstrated the phathalocynine organic superlattice, which is a structure composed of periodically alternating crystalline layers of H2Pc and F16CuPc. A periodical crystal structure and electronic structure appear in this organic superlattice system. High density of mobile electrons and holes distribute periodically in F16CuPc and H2Pc layers, respectively, leading to a significant change in intrinsic properties of organic semiconductors. [ABSTRACT FROM AUTHOR]

Au-gated AlGaN/GaN high electron mobility transistor (HEMT) structures were functionalized in the gate region with label-free 3′-thiol-modified oligonucleotides. This serves as a binding layer to the AlGaN surface for hybridization of matched target deoxyribonucleic acid (DNA). X-ray photoelectron spectroscopy shows the immobilization of thiol-modified DNA covalently bonded with gold on the gated region. Hybridization between probe DNA and matched or mismatched target DNA on the Au-gated HEMT was detected by electrical measurements. The HEMT drain-source current showed a clear decrease of 115 μA as this matched target DNA was introduced to the probe DNA on the surface, showing the promise of the DNA sequence detection approach for biological sensing. [ABSTRACT FROM AUTHOR]

An approach is proposed to develop recording materials for high speed phase change optical data storage. It utilizes a thin film alloy mixture between a stoichiometric GeSbTe alloy and an additive ternary telluride alloy. Selection rules for an additive alloy are suggested. For a test, (Ge[sub 1]Sb[sub 2]Te[sub 4])[sub 1-x](Sn[sub 1]Bi[sub 2]Te[sub 4])[sub x] thin films are deposited by co-sputtering and their structural and thermal properties are studied. Ge[sub 1]Sb[sub 2]Te[sub 4] and Sn[sub 1]Bi[sub 2]Te[sub 4] are found to form a completely soluble pseudo-binary system, whose crystalline lattice parameters obey Vegard's rule over the entire range of x (0

Describes the fabrication of a scanning Hall-sensor microscope that can be served as a simple and conventional tool for nondestructive evaluation of magnetic materials. Active area of the microscope; Magnetic detection of small cracks in mild steels; Operation of the microscope.