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We theoretically explore dwell time for electrons in a semiconductor microstructure, which is constructed on the surface of the InAs/Al x In1- x As heterostructure by patterning a ferromagnetic (FM) stripe and a Schottky-metal (SM) stripe in a parallel configuration. Dwell time is found to be dependent on electron spins. Spin-polarized dwell time can be controlled by changing an applied voltage to SM stripe. Thus, electron spins can be separated in time dimension, and such a semiconductor microstructure can be used as an electrically tunable temporal spin splitter for spintronics device applications.

We apply a bias to a magnetoresistance (MR) device, which is constructed on surface of GaAs/AlxGa1– xAs heterostructure by patterning two asymmetric ferromagnetic stripes. Using improved transfer matrix method and Landauer–Büttiker theory, bias-dependent transmission, conductance and magnetoresistance ratio are calculated numerically. An obvious MR effect appears, because of a significant difference of transmission or conductance between parallel (P) and antiparallel (AP) magnetization configurations. MR ratio can be tuned by adjusting magnitude or direction of applied bias. These interesting features not only propose an alternative way to control MR effect, but also put forward an electrically-tunable MR device for magnetic information storage.

We theoretically investigate how to manipulate the wave-vector filtering effect by δ-doping for electrons in a magnetically and electrically confined semiconductor heterostructure, which can be constructed by patterning a ferromagnetic stripe and a Schottky-metal stripe in a parallel configuration on the surface of the GaAs/AlxGa1−xAs heterostructure. The δ-doping dependent transmission is calculated by exactly solving the Schrodinger equation with the help of an improved transfer matrix method. An appreciable wave-vector filtering effect is revealed. Its wave-vector filtering efficiency is found to be tunable by changing the weight or position of the δ-doping. Thus, a structurally controllable momentum filter can be obtained for nanoelectronics device applications.

Based on a magnetically confined GaAs/Al x Ga1– x As microstructure modulated by spin-orbit coupling (SOC), we propose a controllable electron-spin filter for spintronics applications. This device operates due to both Zeeman interaction and Rashba or Dresselhaus SOC. Its spin polarization can be tuned by changing interfacial confining electric field or engineering strain.

We report a theoretical investigation on Goose-Hänchen (GH) effect for spin electrons across a magnetically confined GaAs/AlxGa1-xAs microstructure modulated by spin-orbit coupling [(SOC), including Rashba and Dresselhaus types]. An intrinsic symmetry in the device is broken by SOC, which gives rise to a considerable spin polarization effect in GH shifts of electrons. Both magnitude and direction of spin polarization can be manipulated by Rashba or Dresselhaus SOC, i.e., interfacial confining electric field or strain engineering. Based on such a semiconductor microstructure, a controllable spatial spin splitter can be proposed for spintronics applications.

Based on antiparallel asymmetric double δ-magnetic-barrier semiconductor microstructure constructed on the surface of GaAs/Al1-xGaxAs heterostructure by patterning two ferromagnetic stripes, an electron-momentum filter was proposed recently. We further explore the effect of a δ-potential realized by the atomic-layer doping technique on this filter device. It is shown that this filter is sensitive to the δ-potential because the effective potential experienced by electrons in the device depends on the δ-potential. It is also shown that both magnitude and sign of wave-vector filtering efficiency can be tuned by adjusting weight or position of the δ-potential. Therefore, a controllable electron-momentum filter may be obtained for nanoelectronics device applications.

Semiconductor-based magnetoresistance (MR) device has many advantages such as high MR ratio at low switching magnetic field, but electron spins were ignored completely in previous researches. Electron spins should impact on performance of semiconductor-based MR device, as electron spins interact with magnetic fields. By considering a semiconductor microstructure constructed on GaAs/AlxGa1-xAs heterostructure by patterning two asymmetric ferromagnetic (FM) stripes, we theoretically explore effect of electron spins on semiconductor-based MR device. An interesting spin splitting effect is found in semiconductor-based MR device. Both magnitude and sign of spin splitting effect can be modified by applying a negative voltage. These findings may be helpful for designing semiconductor-based MR devices.

We theoretically investigate how to modulate spin-dependent lateral shifts by the spin-orbit coupling (SOC) in a hybrid magnetic-electric-barrier (MEB) nanostructure, which can be experimentally realized by depositing a ferromagnetic (FM) stripe and a Schottky metal (SM) stripe on the top and bottom of the semiconductor heterostructure, respectively. Two kinds of ROCs, Rashba SOC (RSOC) and Dresselhaus SOC (DSOC), are taken into account fully. The Schrodinger equation of the spin electron in the hybrid MEB nanostructure is exactly solved by using the improved transfer-matrix method (ITMM), and the lateral shift and its spin polarization are numerically calculated with the help of the stationary phase method (SPM). Theoretical analysis indicates that the spin polarization effect in the lateral shift still exists in the hybrid MEB nanostructure when the SOCs are considered. Numerical simulations show that both magnitude and sign of the spin polarization effect in lateral shifts vary strongly with the strengths of RSOC and DSOC. These interesting features may offer an effective means to control the behavior of spin-polarized electrons in the semiconductor nanostructure, and such a hybrid MEB nanostructure serves as a SOC-manipulable spatial spin splitter for spintronic applications.

We theoretically explore to manipulate the electron-spin polarization by a δ-potential in 3-layered semiconductor heterostructure modulated by the Rashba spin-orbit-coupling. An obvious electron-spin polarization effect still exists even if the δ-potential is embedded inside. Both size and sign of the electron-spin polarization can be tuned by changing the weight or position of the δ-potential. Therefore, a controllable spin filter can be obtained for spintronics device applications.

We report a theoretical exploration on the control of the Dresselhaus －spin-orbit －coupling (SOC) induced spin polarization via the δ-doping for electrons in the 3-layered semiconductor heterostructure (3-LSH). It is shown that an obvious electron-spin polarization effect still exists when a δ-doping is introduced inside. Moreover, both magnitude and sign of the spin polarization can be controlled by adjusting the weight or position of the δ-doping. Therefore, spin-polarized electrons can be manipulated by the δ-doping technique, and the considered 3-LSH can be used as a structurally-controllable spin filter, which may be helpful for spintronics device applications.

We propose to separate electron-spins by transmission time for electrons across a semiconductor microstructure. By calculating dwell time of electrons in a realistic magnetic microstructure, transmission time is found to be spin related, electron spins are, therefore, separated in time dimension. Besides, both magnitude and sign of spin-polarized dwell time can be manipulated by an applied voltage, which may give rise to an electrically-controllable temporal spin splitter for spintronics device applications.

A giant magnetoresistance (GMR) device formed by depositing two parallel nanosized ferromagnetic strips on top of a semiconductor heterostructure has been proposed theoretically (Zhai et al. in Phys Rev B 66:125305, 2002). For the sake of manipulating its performance, we introduce a tunable δ-potential into this device with the help of atomic-layer doping techniques such as molecular beam epitaxy (MBE) or metal-organic chemical-vapor deposition. We investigate theoretically the impact of such δ-doping on the magnetoresistance ratio (MR) of the GMR device. We find that, although the δ-doping is embedded in the device, a considerable GMR effect still exists due to the significant difference in electronic transmission between parallel (P) and antiparallel (AP) configurations. Moreover, the calculated results show that the MR of the GMR device varies sensitively with the weight and/or position of the δ-doping. Thus, the GMR device can be controlled by changing the δ-doping to obtain an adjustable GMR device for magnetoelectronics applications.

We report on a theoretical study of the influence of a δ-doping on a giant magnetoresistance (GMR) device based on a magnetically confined GaAs/AlxGa1⿿xAs heterostructure. The δ-doping dependent transmission and conductance of the device are calculated. It is shown that there still exists an obvious GMR effect even the inclusion of a δ-doping. It is also shown that the magnetoresistance ratio (MR) of the device can be switched by changing the weight and/or position of the δ-doping. These interesting features provide an alternative way to manipulate a GMR device, and the structure can be employed as a structurally controllable GMR device for magnetoelectronics applications.

We theoretically explore to separate electron-spins by dwell time of electrons through a magnetic microstructure with a δ-doping, which is fabricated on surface of InAs/AlxIn1-xAs heterostructure by patterning a ferromagnetic (FM) stripe. It is shown that dwell time is spin related due to both spin-field interaction and broken symmetry. It is also shown that spin-polarized dwell time can be manipulated structurally because of δ-doping dependent effective potential. Therefore, electron spins can be separated in time dimension and such a magnetic microstructure can serve as a controllable temporal spin splitter.

Considering Dresselhaus-type spin–orbit coupling (SOC), we theoretically investigate spin-polarized transport in a 3-layered semiconductor heterostructure, InSb/InxGa1-xAs/GaSb. Adopting improved transfer matrix method to solve Schrodinger equation, electronic transmission coefficient is obtained exactly, and then spin polarization ratio is evaluated. An appreciable electron-spin polarization effect by the Dresselhaus-SOC appears in this layered semiconductor heterostructure. Spin polarization is associated closely with in-plane wave vector, incident direction and SOC strength. In particular, both magnitude and sign of spin polarization are manipulated by strain engineering or an appropriate intermediate-layer. Therefore, such a 3-layered semiconductor heterostructure can serve as a controllable spin filter for spintronics device applications.

In layered semiconductor heterostructure, there exists spin-orbit coupling (SOC), which can induce electron-spin polarization. Considering a realistic 3-layered semiconductor heterostructure, InSb/InxGa1-xAs/GaSb, we present a theoretical study of spin polarized transport by the Rashba-SOC type. An obvious electron-spin polarization effect is found in such a 3-layered system, and its degree is related to in-plane wave vector, Rashba-SOC strength and intermediate-layer parameters. Both magnitude and sign of spin polarization can be manipulated by tuning interfacial confining electric field or fabricating intermediate layer properly. These interesting features may be useful for exploring new way of spin injection and designing controllable spin filter for spintronics applications.

Wave vector filtering effect is explored for electrons in magnetically and electrically confined semiconductor heterostructure, which can be realized experimentally by depositing a ferromagnetic stripe and a Schottky metal stripe in parallel configuration on the surface of [Formula: see text] heterostructure. Adopting improved transfer matrix method to solve Schrödinger equation, electronic transmission coefficient is calculated exactly, and then wave vector filtering efficiency is obtained by differentiating transmission probability over longitudinal wave vector. An obvious wave vector filtering effect appears, due to an essentially two-dimensional process for electron transmission through a magnetic nanostructure. Besides, wave vector filtering efficiency is associated closely with width, position and externally applied voltage of Schottky metal stripe, which makes wave vector filtering effect become controllable and results in a manipulable momentum filter for nanoelectronics.

By means of a hybrid magnetic–electric barrier (MEB) on the top of the semiconductor InAs/AlxIn1−xAs heterostructure, a spin filter can be obtained. In this work, we introduce a δ-doping into this MEB device by molecular beam epitaxy or metal-organic chemical-vapor deposition, to manipulate the spin filtering. With the help of the improved transfer-matrix method and Landauer–Bűttiker theory, transmission coefficient, conductance and spin polarization are calculated for the electrons across this device. Due to spin-field interaction between electron spins and magnetic fields, an obvious spin filtering effect remains in the device even if a δ-doping is included inside. The behavior of spin-polarized electrons is related closely to the δ-doping, due to the strong dependence of the effective potential experienced by the electrons on such a doping. Degree of spin polarization can be manipulated by properly adjusting weight or position of the δ-doping, which gives rise to a structurally controllable spin filter.

We theoretically investigate Goos-Hänchen (GH) displacement by modelling the spin transport in an archetypal device structure-a magnetically confined GaAs/Al

We theoretically investigate a tunable δ-potential effect on a spin spatial splitter, which can be realized experimentally by depositing a ferromagnetic stripe with a vertical magnetization on top of semiconductor heterostructure and using atomic-layer doping technique. With the help of stationary phase method, the δ-doping dependent spin-polarized lateral displacement is numerically calculated by means of the improved transfer-matrix technique. Both amplitude and sign of the spin polarized lateral displacement are found to vary dramatically with the weight and/or location of the δ-doping. Thus, a structurally tunable spin spatial splitter can be achieved for spintronic applications.

Taking ‘Fuji’ fresh-cut apples as material, studied on the effect of different temperatures (-2 ̊C,0 ̊C,2 ̊C and 4 ̊C) on storage quality of fresh-cut apples during 25 days. The results indicated that low temperature can significantly keep the storage quality of fresh-cut apples and inhibit browning. Moreover, compared to the other treatment groups, treatment at 0 ̊C better maintained the firmness, color, as well as higher contents of titratable acid and lower MDA content, which showed 0 ̊C can extent storage time.

This paper investigated the microbial infection of postharvest diseases of Dapingding jujube and cited the symptoms of common rot disease .At the same time, the antibacterial effect of cinnamon oil, natamycin and their composition on Dapingding jujube during the period of storage were studied. The results showed that the preservation inhibitory effect of cinnamon oil was better than natamycin at earlier storage, but just the opposite at later storage, while, the effect of the composition had been very good during the whole storage with higher rate of intact fruit, better fruit firmness and lower cankered index.

The quality of kiwifruit with three different maturities were studied on the shelf life. Different maturity of kiwifruits were stored at 0±0.5°Cfor 50 days and then taken them at 20±0.5°C for 12 days.Results showed that the kiwifruits with the firmness of 13kg cm-2 can keep a relative good quality during the shelf life.

The experiment was carried to study the fermentation regularity of different maturity, so as to provide theoretical basis for the effective storage of Lingwu long jujubes. The results showed that with the increase of maturity, the fermentation rate of fruits also increased, and the fermentation rate of eight, nine, ten mature fruits had significant differences, and the seven, eight mature were not. Based on the fermentation regularity and other quality indicators, the conclusion was that the storage of Lingwu long jujubes should be appropriate to eight mature jujube.

A controllable spin filter is proposed by theoretically investigating spin polarization in a magnetic microstructure constructed on surface of GaAs/AlxGa1-xAs heterostructure by patterning a horizontally-magnetized ferromagnetic stripe. Due to a broken intrinsic symmetry by spin-orbit coupling, a spin polarization effect appears in the magnetic microstructure. Degree of spin polarization can be modified by changing strength of spin-orbit coupling, which may be helpful for design of controllable spin-polarized source.

A magnetoresistance device was proposed by patterning two asymmetric ferromagnetic stripes on top and bottom of the GaAs/AlxGa1-xAs heterostructure. To control its performance, a tunable δ-potential is introduced inside this device by wire-like doping. Adopting transfer matrix method and Landauer-Buttiker conductance theory, Schrodinger equation is solved analytically and δ-doping dependent transmission, conductance and magnetoresistance ratio are calculated. An obvious magnetoresistance effect still stays in this device, due to existence of transmission difference between parallel and antiparallel configurations independent of δ-doping. However, its magnetoresistance ratio can be tuned by changing weight or position of δ-doping. These interesting results not only propose an alternative scheme to manipulate magnetoresistance device, but also a structurally-controllable magnetoresistance device can be obtained for magnetic information storage.

We present a theoretical study on the spin-dependent Goos–Hanchen (GH) effect in a two-dimensional electron gas modulated by ferromagnetic and Schottky metal (SM) stripes. The GH shifts for spin electron beams across this device are calculated with the help of the stationary phase method. It is shown that the GH shift of spin-up beam is significantly different from that of spin-down beam, i.e., this device shows up a considerable spin polarization effect in GH shifts of electron beams. It also is shown that both magnitude and sign of spin polarization of GH shifts are closely related to the stripe width, the magnetic strength and the gated voltage under SM stripe. These interesting properties not only provide an effective method of spin injection for spintronics application, but also give rise to a tunable spin beam splitter.

The study shows for the first time the presence of the Klebsiella oxytoca strain fp10 coproducing plasmid-mediated KPC-2 and IMP-8 carbapenemases. The strain was obtained from the fecal sample of an inpatient and showed high-level resistance to imipenem and ertapenem (MICs > 32 μg/ml). Conjugation experiments demonstrated the transferability of the carbapenem-resistant determinants. The results of plasmid analysis and Southern hybridization revealed that the bla KPC-2 gene was located on transferable plasmid pFP10-1 (∼54 kb), whereas the bla IMP-8 gene was on transferable plasmid pFP10-2 (∼180 kb). Analysis of the genetic environment of these two genes has demonstrated that IS Kpn6 and IS Kpn8 are involved in the spread of the bla KPC-2 gene, while the transposable elements IS 26 , intI1 , and tniC might contribute to the dissemination of the bla IMP-8 gene. The chimera of several transposon-associated elements indicated a novel genetic environment of IMP-type metallo-β-lactamase gene in Enterobacteriaceae from China.

Antibiotic therapy can affect not only the pathogenic bacteria, but also commensal microorganisms in the gut flora of humans, which might serve as a reservoir of antimicrobial resistance genes.1 Es...

The community could be a reservoir of antibiotic resistance genes. The aim of this study was to investigate the prevalence and genetic environments of bla(CTX-M) among faecal Escherichia coli obtained from healthy persons in a region of China.Bacteria in stool specimens were screened for extended-spectrum β-lactamase (ESBL) production on 2 MacConkey agars, one with cefotaxime and one with ceftazidime. bla(CTX-M) and their genetic environments, as well as phylogenetic analysis and detection of the O25b-ST131 clone of E. coli, were characterized by polymerase chain reaction and sequencing. Pulsed field gel electrophoresis and conjugation assays were performed by standard procedures.A surprisingly high number (50.5%, 55/109) of faecal samples showed the presence of ESBL-producing E. coli. bla(CTX-M) genes were detected in all of these strains. The CTX-M-9 group (41/55, 74.5%) was found most frequently, followed by the CTX-M-1 group (16/55, 29.1%). CTX-M-14 (n = 39) was the predominant CTX-M enzyme in this study. However, the genes for the CTX-M-2 and CTX-M-8 groups were not observed. ISEcp1 was detected in 90.9% of the strains, while IS26 was observed upstream from bla(CTX-M) in only 1 strain. Phylogenetic groups A and D were found to predominate in commensal E. coli. High clonal diversity was observed and most bla(CTX-M) genes were transferable. The O25b-ST131 clone was found in 4 strains.This study reveals the wide dissemination of CTX-M ESBL-producing E. coli in the gut flora of healthy individuals in China.

We theoretically investigate Goos-Hanchen (GH) displacement by modelling the spin transport in an archetypal device structure-a magnetically confined GaAs/Al x Ga1-x As nanostructure modulated by spin-orbit coupling (SOC). Both Rashba and Dresselhaus SOCs are taken into account. The degree of spin-polarized GH displacement can be tuned by Rashba or Dresselhaus SOC, i.e. interfacial confining electric field or strain engineering. Based on such a semiconductor nanostructure, a controllable spatial spin splitter can be proposed for spintronics applications.

The study of phylogenetic groups and pathogenicity island (PAI) markers in commensal Escherichia coli strains from asymptomatic Chinese people showed that group A strains are the most common and that nearly half of all fecal strains which were randomly selected harbor PAIs.

Extended-spectrum β-lactamase (ESBL)-producing Enterobacteriaceae have been of concern for many years, and clinicians, microbiologists, infection control practitioners, and hospital epidemiologists are struggling to overcome them. It is necessary to characterize the epidemiology of ESBL-producing

We theoretically investigate modulation of a tunable δ-potential to the lateral displacement of electrons across a magnetically modulated semiconductor nanostructure. Experimentally, this nanostructure can be produced by depositing a nanosized ferromagnetic stripe with in-plane magnetization on top of a semiconductor heterostructure, while the δ-potential can be realized by means of the atomic layer doping technique. Theoretical analysis reveals that this δ-doping can break the intrinsic symmetry in nanostructure and a considerable spin polarization in the lateral displacement will appear. Numerical calculations demonstrate that both magnitude and sign of spin polarization can be manipulated by changing the height and/or position of the δ-doping, giving rise to a structurally tunable spin spatial splitter.