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The amorphous chalcogenide glass Sn1As20S79 is demonstrated to undergo permanent changes in refractive index on irradiation with ultraviolet light. The refractive properties of this material and the effect of annealing at temperatures below the glass transition temperature are investigated in detail. An Sn1As20S79 strip waveguide is fabricated using this photoinduced refractive index change, and the device is shown to function as expected with good propagation characteristics for the 632.8 nm guided mode. [ABSTRACT FROM AUTHOR]

Changes in the refractive index and thickness of amorphous As2S8 semiconductor film are observed under illumination, annealing–illumination, and annealing-illumination cycles. Properties of the As2S8 film are measured using techniques of prism coupler, x-ray diffraction spectra and Raman spectra. After light illumination the refractive index change in an as-deposited As2S8 film is one order of magnitude greater than that of an annealed As2S8 film, corresponding to ∼0.06 and ∼0.0057, respectively. Photoexpansions with a change in the relative film thickness of the as-deposited and annealed As2S8 film are nearly -3.5% and -2.1%, respectively, which exhibit the photodensification. The full reversibility of the photoinduced refractive index change is claimed on an annealed As2S8 film sample. [ABSTRACT FROM AUTHOR]

Optical nonlinearities in the undoped As20S80, low doped P2As20S78 and Sn1As20S79 chacogenide glasses are investigated by using Z-scan method. These experiments show that at 1064 nm the figure of merit (FOM) for As20S80 is ∼1.02, while for Sn1As20S79 increases to ∼1.42, and for P2As20S78 decreases to ∼0.83. These resulted data indicate the addition of Sn in As20S80 system chalcogenide glass can enhance FOM due to creating narrow energy gaps. In addition, the self-phase modulation (SPM) width experiment for Sn1As20S79 strip waveguide displays that the full width half maximum (FWHM) of spectral width increases approximately 0.8 nm under the induction of bandgap light, meaning that the bandgap light can induce to enhance its optical nonlinearity with the nonlinear refractive index of n2≅5.27×10−14 cm2/W. [ABSTRACT FROM AUTHOR]

Amorphous As2S8 chalcogenide glass is shown to undergo changes in the refractive index upon exposure to ultraviolet light. This phenomenon is employed to fabricate an As2S8 stripe waveguide, which is shown to be an effective guided mode device with a useful switching functionality based on the photo-optical effect. [ABSTRACT FROM AUTHOR]

Ginseng (Panax ginseng) is a perennial herbaceous plant belonging to Panax genus of Araliaceae. Ginsenosides are a kind of important compounds in ginseng and minor ginsenosides are secondary metabolic derivatives of ginsenosides. Studies have shown that minor ginsenosides have many pharmacological effects, such as antioxidant, anti-tumor, anti-platelet aggregation, and neuroprotective effects. However, the therapeutic effects of minor ginsenosides are limited due to poor solubility in water, short halflife, and poor targeting accuracy. In recent years, to improve the application efficiency, the research on the nanocrystallization of minor ginsenosides have attracted extensive attention from researchers. This review focuses on the classification, preparation methods, pharmacological effects, and action mechanisms of minor ginsenoside nanoparticles, as well as existing problems and future direction of relevant research, which provides a reference for the in-depth research of minor ginsenoside nanoparticles. [ABSTRACT FROM AUTHOR]

An unconventional method of nonlocal spin detection is demonstrated in mesoscopic lateral spin valves at room temperature. Clear nonlocal spin signals are detected between the two ends of an extended ferromagnetic spin detector. This is different from the conventional method in which the nonlocal voltage is measured between the spin detector and the nonmagnetic channel. The results can be understood as spatially non-uniform absorption of a pure spin current into the spin detector across a low-resistance oxide interface. [ABSTRACT FROM AUTHOR]

The purpose of this study was to examine the associations of social support and self-efficacy with physical Activity (PA) and the mediating effect of self-efficacy on the relationship between social support and PA in Chinese adolescents. Participants included a total of 2341 Chinese adolescents (aged 12.75 ± 1.46 years). Self-reported instruments, including the physical activity questionnaire for adolescents, the social support revalued scale and the exercise self-efficacy scale, were used to measure physical activity, social support and exercise self-efficacy. Results showed that social support (r = 0.29, p < 0.05) and exercise self-efficacy (r = 0.43, p < 0.05) were significant and positive predictors of PA among Chinese adolescents, and exercise self-efficacy was a significant mediator in the relationship between social support and PA (standardized effect size = 0.15, p < 0.001). Such findings were evident with similar patterns in both male and female adolescents. The findings of this study have indicated the importance of social support and exercise self-efficacy on PA promotion in adolescents, which will aid the development of effective interventions in this population. [ABSTRACT FROM AUTHOR]

Acute respiratory distress syndrome (ARDS) is a devastating hypoxemic respiratory failure, characterized by disruption of the alveolar-capillary membrane barrier. Current management for ARDS remains supportive, including lung-protective ventilation and a conservative fluid strategy. Mesenchymal stem cells (MSCs) have emerged as a potentially attractive candidate for the management of ARDS through facilitating lung tissue regeneration and repair by releasing paracrine soluble factors. Over the last decade, a variety of strategies have emerged to optimize MSC-based therapy. Among these, the strategy using genetically modified MSCs has received increased attention recently due to its distinct advantage, in conferring incremental migratory capacity and, enhancing the anti-inflammatory, immunomodulatory, angiogenic, and antifibrotic effects of these cells in numerous preclinical ARDS models, which may in turn provide additional benefits in the management of ARDS. Here, we provide an overview of recent studies testing the efficacy of genetically modified MSCs using preclinical models of ARDS. [ABSTRACT FROM AUTHOR]

Cobalt/copper nonlocal spin valve devices with AlOx barriers are fabricated for the purpose of spin-transfer with a pure spin current. The submicron planar device consists of a Co spin injector (F1), a Co spin detector (F2), and a Cu channel. The F2 Co electrode is only 2.5 nm thick, but sizable nonlocal spin signals of 2–4 mΩ are measured at 4.2 K. The spin-transfer switching has been achieved with the assistance of a magnetic field. The magnetizations of F1 and F2 electrodes are set to an antiparallel state by sweeping the magnetic field. The magnetic field is then held at a value smaller but close to the switching field of F2. A small dc current (0.1–1 mA) is sufficient to switch F2 into being parallel with F1. Analysis has been done to rule out possible artifacts due to Oersted fields. [ABSTRACT FROM AUTHOR]

Charge density wave (CDW) order is ubiquitous among low-dimensional electronic systems, as realized in layered materials such as various 1T and 2H polytypes of transition metal dichalcogenides (TMDs). In particular, 2H-TaS2, a prominent member of the vast family of TMDs, hosts a canonical CDW phase transition whose mechanism remains controversial even after decades of research. Using state-of-the-art angle resolved photoemission spectroscopy (ARPES) measurements, we report, for the first time, pronounced many-body renormalizations in 2H-TaS2. These renormalizations are manifested by the presence of multiple slope changes, known as “kinks”, in the electronic dispersions. The temperature independence of the kink energies and their close correspondence with the phonon frequencies of the system evidence that these renormalizations are caused by electron–phonon interactions. In addition, the electron–phonon coupling parameter is momentum-dependent, and the CDW vector is not compatible with any of the Fermi surface nesting vectors. Collectively, these observations establish that the origin of the CDW transition in 2H-TaS2 is not the same as that of the Peierls ordering transition, rather this transition is triggered by strong electron–phonon coupling including its momentum anisotropy. The commonality between the ARPES data on 2H-TaS2 and those on 2H-TaSe2 and 2H-NbSe2 rationalize the above interpretation of the CDW transition being generic to incommensurate CDW orders in 2H polytypes of TMDs. [ABSTRACT FROM AUTHOR]

The effective plasma frequency (EPF) for a one-dimensional superconductor-metamaterial photonic crystal (PC) is theoretically analyzed by making use of the transfer matrix method together with Bloch theorem. The EPF in a PC is defined as the lowest frequency at which an electromagnetic wave can start to propagate through the PC. It is found that the EPF can be larger or smaller than the bulk plasma frequency of the superconductor. The EPF can even be zero when the suitable parameters are chosen. The filling factor of the metamaterial layer has an important influence on the EPF. If the filling factor is large enough, the EPF can keep being zero and is independent of the relative permittivity of metamaterial and the operating temperature. The effects of the thickness of the metamaterial layer, the thickness of the superconductor layer, the relative permittivity of metamaterial, and the operating temperature on the EPF are also discussed. [ABSTRACT FROM AUTHOR]

We study a host-pathogen system in a bounded spatial habitat where the environment is closed. Extinction and persistence of the disease are investigated by appealing to theories of monotone dynamical systems and uniform persistence. We also carry out a bifurcation analysis for steady state solutions, and the results suggest that a backward bifurcation may occur when the parameters in the system are spatially dependent. [ABSTRACT FROM AUTHOR]

Single crystals of Cu xTa1+ ySe2 were grown by chemical vapor transport. Single crystals of different compositions were obtained at slightly different reaction conditions from mixtures of the reactants of the same nominal composition. It is suggested that different diameters of the ampoules imply different contributions of convection and diffusion to the mass transport, and thus are responsible for different ratios of the amount of Cu, Ta, and Se transported. 2H-Cu0.52TaSe2 ( x = 0.52, y = 0) is formed in the narrower ampoule (diameter 15 mm). The crystal structure is based on the MoS2 type of stacking of TaSe2 layers. Partial ordering of Cu over the tetrahedral sites is responsible for a 2 a0 × 2 b0 × c0 superstructure with hexagonal P $\bar{6}$ m2 symmetry [ a0 = 3.468 (1) Å, c0 = 13.568 (3) Å]. 2H-Cu0.16Ta1.08Se2 ( x = 0.16, y = 0.08) is formed in the wider ampoule (diameter 18 mm). It possesses a NbS2-type of stacking. A superstructure is not formed, but the presence of Cu and intercalated Ta in alternating van der Waals gaps is responsible for the reduction of symmetry from P63/ mmc to P $\bar{6}$ m1 [ a0 = 3.439 (2) Å, c0 = 12.870 (2) Å]. Single crystals are formed towards the hotter side of the ampoules up to a temperature of 1168 K in both reactions. [ABSTRACT FROM AUTHOR]

The vortex motion in Cu0.03TaS2 has been investigated by resistivity results with a special electrode arrangements. The vortex behaviors for H c are completely different from that for H ab. The analysis indicates that when H ab, the sharp ρ - T transition is the superconductive-normal transition while for H c, the broadened ρ - T transition is caused by the suppression of the superconducting weak link between the S-Ta-S layers. The existence of the vortex pancake in Cu0.03TaS2 is contradictory to the Clem's model, further demonstrating that the models for high temperature cuprates superconductors are not applicable to the layered transition metal dichalcogenides. [ABSTRACT FROM AUTHOR]

In this work, we investigated a scalability of spin accumulation signal for various device sizes. We found that the spin accumulation signal is enhanced by shrinking Cu wire width and thickness. Moreover we estimate the signal to noise ratio (SNR) of a spin accumulation head structure by using the size dependence of spin accumulation signal. The SNR increases with reducing nonmagnetic wire width and thickness, which are corresponding to a track width and a gap width, respectively. And it has the maximum value around 2\sim 3\ \Tbit/inch^2 resolution. From these results, it has a possibility that spin accumulation effect is applicable to a new read head for high density hard disk drive. [ABSTRACT FROM AUTHOR]

The eightfold 2a0×2b0×2c0 superstructures of 6R-Cu xTa1+ yS2 are reported for crystal A with x = 0.237 and y = 0, and crystal B with x = 0.23 and y = 0.06. Compelling evidence is presented for the self-intercalation of tantalum onto octahedral sites, based on the diffraction data and crystal chemical arguments. The eightfold superstructure is formed by partial vacancy ordering within planes of intercalated atoms, while the stacking of TaS2 layers remains that of the 6R polytype. Temperature-dependent X-ray diffraction experiments show that the superstructure exists between T = 14 K and at least 370 K. Intercalated atoms enter the compound at octahedral and tetrahedral sites in alternating Van der Waals gaps. Intercalation is inhomogeneous, with average occupancies varying between 0.11 for octahedral sites within one Van der Waals gap and 0.23 for the tetrahedral sites within another Van der Waals gap. It is proposed that partial vacancy ordering is governed by the principle of maximum separation between intercalated atoms. [ABSTRACT FROM AUTHOR]

A subwavelength plasmonic indented waveguide with an active In GaAsP core is proposed. The characteristics of the gap plasmon mode and gain required for lossless propagation are investigated and analyzed by the finite element method. We numerically calculate the normalized mode areas and percentages of energy confined in In GaAsP and metal for plasmonic nanolaser applications. It is shown that the indentation of the sidewalls has an optimal value for which the lasing threshold gain is minimal. The structure could enable low-threshold subwavelength lasing and applications for optoelectronic integrated circuits. [ABSTRACT FROM AUTHOR]

The origin of high surface spin-flip rate in metallic nonlocal spin valves has been explored by tracking the evolution of the spin signals during the natural oxidation of the devices in air. The temperature dependence of spin signals evolves from a non-monotonic dependence with a maximum at ∼60 K for as-fabricated devices to a monotonic increase with decreasing temperatures for fully oxidized devices. The experimental results suggest that the high surface spin-flip rate originates from magnetic impurities near the side surfaces of the nonmagnetic channel and can be reduced by oxidation. [ABSTRACT FROM AUTHOR]

We performed measurements of Py/Cu and Py/Ag lateral spin valves as a function of injection current direction and magnitude. Above a 'critical' current, there is an unexpected dependence of spin injection on current direction. Positive currents show higher polarization of spin injection than negative. This implies that in addition to current-induced spin injection, there is a thermally induced injection from a spin-dependent Seebeck effect. A temperature gradient in the Py electrode, caused by Joule heating, is responsible for injecting excess spins into the non-magnetic channel. This effect has important consequences for understanding high-current spin-based devices, such as spin transfer torque devices. [ABSTRACT FROM AUTHOR]

A large spin signal (ΔRs) of 12.8 mΩ at room temperature is demonstrated in an all-metallic lateral spin valve (LSV) device comprising of ferromagnetic wire of a highly spin-polarized Co2Fe(Ge0.5Ga0.5) Heusler alloy and a Cu wire. From the results on multi-terminal LSV devices, the origin of the large ΔRs was concluded to be the high spin polarization of Co2Fe(Ge0.5Ga0.5) and the resultant small spin absorption. The all-metallic LSV device without MgO barrier has low contact resistance, which is considered to be beneficial for a high frequency ultrathin read sensor for the next generation ultrahigh density magnetic recording. [ABSTRACT FROM AUTHOR]

Cobalt-copper nonlocal spin valves are fabricated by shadow evaporation through nanoscale masks. The thickness of Co electrodes is varied and the spin diffusion length of the Cu channel is determined. Short spin diffusion lengths are found in devices with thick (>20 nm) Co layers. Co impurities are introduced into the Cu channel in the shadow evaporation process during the fabrication, and the impurities cause spin-flip scattering. The amount of Co impurities can be reduced by decreasing the thicknesses of Co electrodes. Spin diffusion lengths of ∼400 nm at 295 K and ∼800 nm at 4.2 K are measured in devices with thin (<10 nm) Co layers. [ABSTRACT FROM AUTHOR]

Spin-transfer effects induced by pure spin currents are explored in nonlocal spin valves by using sustained injection currents. Compared to pulsed injection currents used in previous experiments, this approach provides persistent spin-transfer torques and preserves the history of the reversal process. A nanoscale domain in a magnetic wire can be switched reversibly by the sustained pure spin currents. In addition, dips in nonlocal spin signal curves are observed at high magnetic fields for only one polarity of the injection currents. This indicates stable-state magnetization precession around the external field driven by the sustained pure spin currents. [ABSTRACT FROM AUTHOR]

Large nonlocal spin valve signals are reported in mesoscopic Ni80Fe20/Ag lateral spin valves upon exposing them to air. Magnetotransport measurements combined with transmission electron microscopy show that the formation of a native oxide layer at the Ni80Fe20/Ag interface is responsible for the large signals. The results indicate that lateral spin valves with superior performance to those based on high-resistance tunnel barriers can be achieved via controllable growth of native permalloy oxides. [ABSTRACT FROM AUTHOR]

We have systematically investigated the interface contributions to the spin injection characteristics in permalloy/MgO/Ag lateral spin valves. The spin valve signal remarkably increases with MgO thickness and reaches a maximum when the interface resistance is about 100 fΩ m2 for 1 nm thick MgO, which is two orders of magnitude lower than that of the typical tunnel junction. Our quantitative analysis based on the spin-dependent diffusion equation considering variable spin polarization in the MgO layer well describes the observed trend in the spin valve signals. [ABSTRACT FROM AUTHOR]

Submicron metallic lateral spin valves are fabricated with AlOx tunnel junctions as spin injection and detection barriers. The spin polarization is estimated to be ∼20%, determined by both Hanle effect and variations of device dimensions. The polarization is maintained at a large dc injection current density >2×106 A/cm2. Both the spin polarization and spin diffusion length are weakly temperature dependent. [ABSTRACT FROM AUTHOR]

The effect of interface on the spin injection characteristics in lateral spin valves with Permalloy/MgO/Ag junctions has been studied. The spin valve signal drastically increases after the insertion of a thin MgO layer in the local and nonlocal spin injection schemes. We analyze our results based on the spin-dependent diffusion equation. This reveals that the interface resistance of ∼100 fΩm2 could effectively overcome the spin resistance mismatch between ferromagnetic and nonmagnetic metals. [ABSTRACT FROM AUTHOR]

Large spin signals up to 38 mΩ are demonstrated in mesoscopic nonlocal spin valves with silver channels. Scanning electron microscope images reveal Volmer–Weber growth of the silver channels, which consist of coalesced silver islands from 30 to 80 nm in size. The temperature dependence of the spin signals is monotonic, in contrast to previously observed non-monotonic features due to high surface spin-flip rate. We hypothesize that magnetic impurities in the silver are primarily segregated at the bulk grain boundaries instead of near the side surfaces of the channel, resulting in an absence of high surface spin-flip rate. [ABSTRACT FROM AUTHOR]

We have investigated the effect of annealing on the nonlocal spin valve signal in lateral spin valves with permalloy/MgO/Ag junctions. The results show that annealing up to 400 °C pushes up the spin polarization of the MgO interface to 38%, resulting in an increase in the nonlocal spin valve signal of up to 77.2 mΩ. Further increase in the annealing temperature up to 500 °C causes a decrease in the spin valve signal of 48.0 mΩ. However, the high spin polarization of 55% could be advantageous for the enhancement of the spin accumulation in lateral spin valves. [ABSTRACT FROM AUTHOR]