With an extensive range of distinctive features at nano meter-scale thicknesses,two-dimensional(2D)materials drawn the attention of the scientific community.Despite tremendous advancements in exploratory research on 2...With an extensive range of distinctive features at nano meter-scale thicknesses,two-dimensional(2D)materials drawn the attention of the scientific community.Despite tremendous advancements in exploratory research on 2D materials,knowledge of 2D electrical transport and carrier dynamics still in its infancy.Thus,here we highlighted the electrical characteristics of 2D materials with electronic band structure,electronic transport,dielectric constant,carriers mobility.The atomic thinness of 2D materials makes substantially scaled field-effect transistors(FETs)with reduced short-channel effects conceivable,even though strong carrier mobility required for high performance,low-voltage device operations.We also discussed here about factors affecting 2D materials which easily enhanced the activity of those materials for various applications.Presently,Those 2D materials used in state-of-the-art electrical and optoelectronic devices because of the extensive nature of their electronic band structure.2D materials offer unprecedented freedom for the design of novel p-n junction device topologies in contrast to conventional bulk semiconductors.We also,describe the numerous 2D p-n junctions,such as homo junction and hetero junction including mixed dimensional junctions.Finally,we talked about the problems and potential for the future.展开更多
The InGaN films and GaN/InGaN/GaN tunnel junctions(TJs)were grown on GaN templates with plasma-assisted molecular beam epitaxy.As the In content increases,the quality of InGaN films grown on GaN templates decreases an...The InGaN films and GaN/InGaN/GaN tunnel junctions(TJs)were grown on GaN templates with plasma-assisted molecular beam epitaxy.As the In content increases,the quality of InGaN films grown on GaN templates decreases and the surface roughness of the samples increases.V-pits and trench defects were not found in the AFM images.p++-GaN/InGaN/n++-GaN TJs were investigated for various In content,InGaN thicknesses and doping concentration in the InGaN insert layer.The InGaN insert layer can promote good interband tunneling in GaN/InGaN/GaN TJ and significantly reduce operating voltage when doping is sufficiently high.The current density increases with increasing In content for the 3 nm InGaN insert layer,which is achieved by reducing the depletion zone width and the height of the potential barrier.At a forward current density of 500 A/cm^(2),the measured voltage was 4.31 V and the differential resistance was measured to be 3.75×10^(−3)Ω·cm^(2)for the device with a 3 nm p++-In_(0.35)Ga_(0.65)N insert layer.When the thickness of the In_(0.35)Ga_(0.65)N layer is closer to the“balanced”thickness,the TJ current density is higher.If the thickness is too high or too low,the width of the depletion zone will increase and the current density will decrease.The undoped InGaN layer has a better performance than n-type doping in the TJ.Polarization-engineered tunnel junctions can enhance the functionality and performance of electronic and optoelectronic devices.展开更多
Background:Bacillus cereus is an important pathogen that causes human food poisoning,specifically diarrhea and vomiting.B.cereus can also induce mastitis in dairy cows and has a strong survival ability in milk,as it c...Background:Bacillus cereus is an important pathogen that causes human food poisoning,specifically diarrhea and vomiting.B.cereus can also induce mastitis in dairy cows and has a strong survival ability in milk,as it cannot be inactivated by high-temperature short-time pasteurization.Therefore,B.cereus can enter the market through pasteurized milk and other dairy products,imposing enormous hidden dangers on food safety and human health.Results:In this study,B.cereus 2101(BC)was isolated from milk samples of cows with mastitis.BC grew rapidly with strong hemolysis,making it difficult to prevent mastitis and ensure food security.MAC-T cells were treated with BC and/or Lactobacillus rhamnosus GR-1(LGR-1).Pretreatment with LGR-1 protected the integrity of tight junctions and the expression of zonula occludens-1(ZO-1)and occludin destroyed by BC.Furthermore,LGR-1 pretreatment reduced the expression of NOD-like receptor family member pyrin domain-containing protein 3(NLRP3),caspase recruitment and activation domain(ASC),Caspase-1 p20,gasdermin D(GSDMD)p30,inflammatory factors(interleukin(IL)-1βand IL-18),and cell death induced by BC.Moreover,LGR-1 pretreatment reduced NLRP3 inflammasome activity and increased expressions of ZO-1 and occludin induced by lipopolysaccharides(LPS)+ATP stimulation.MAC-T cells were transfected with NLRP3 si RNA or MCC950 and/or treated with BC and/or LGR-1.NLRP3-si RNA transfection and MCC950 attenuated BC-induced NLRP3 inflammasome activity.Expression of inflammatory cytokines and cell death suggested that the inflammatory pathway might play an important role in the induction of the NLRP3 inflammasome by BC and the protection of LGR-1.Conclusions:These results suggest that LGR-1 might be a probiotic alternative to antibiotics and could be administered to prevent mastitis in dairy cows,thus ensuring food security.展开更多
Photocatalytic water splitting on noble metal-free photocatalysts for H_(2) generation is a promising but challenging approach to realize solar-to-chemical energy conversion.In this study,Mo/Mo_(2)C nanoparticles anch...Photocatalytic water splitting on noble metal-free photocatalysts for H_(2) generation is a promising but challenging approach to realize solar-to-chemical energy conversion.In this study,Mo/Mo_(2)C nanoparticles anchored carbon layer(Mo/Mo_(2)C@C)was obtained by a one-step in-situ phase transition approach and developed for the first time as a photothermal cocatalyst to enhance the activity of ZnIn_(2)S_(4)photocatalyst.Mo/Mo_(2)C@C nanosheet exhibits strong absorption in the full spectrum region and excellent photo-thermal conversion ability,which generates heat to improve the reaction temperature and accelerate the reaction kinetics.Moreover,metallic Mo/Mo_(2)C@C couples with ZnIn_(2)S_(4)to form ZnIn_(2)S_(4)-Mo/Mo_(2)C@C Schottky junction(denoted as ZMM),which prevents the electrons back transfer and restrains the charge recombination.In addition,conductive carbon with strong interfacial interaction serves as a fast charge transport bridge.Consequently,the optimized ZMM-0.2 junction exhibits an H2 evolution rate of 1031.07μmol g^(-1)h^-(1),which is 41 and 4.3 times higher than bare ZnIn_(2)S_(4)and ZnIn_(2)S_(4)-Mo2C,respectively.By designing novel photothermal cocatalysts,our work will provide a new guidance for designing efficient photocatalysts.展开更多
Tight junctions(TJs)are structures between cells where cells appear in the closest possible contact.They are responsible for sealing compartments when epithelial sheets are generated.They regulate the permeability of ...Tight junctions(TJs)are structures between cells where cells appear in the closest possible contact.They are responsible for sealing compartments when epithelial sheets are generated.They regulate the permeability of ions,(macro)molecules and cells via the paracellular pathway.Their structure at the electron microscopic level has been well known since the 1970s;however,only recently has their macromolecular composition been revealed.This review first examines the major macromolecular components of the TJs(occludin,claudins,junctional adhesion molecule and tricellulin)and then the associated macromolecules at the intracellular plaque[zonula occludens(ZO)-1,ZO-2,ZO-3,AF-6,cingulin,7H6].Emphasis is given to their interactions in order to begin to understand the mode of assembly of TJs.The functional significance of TJs is detailed and several mechanisms and factors involved are discussed briefly.Emphasis is given to the role of intestinal TJs and the alterations observed or speculated in diverse disease states.Specifically,intestinal TJs may exert a pathogenetic role in intestinal(inflammatory bowel disease,celiac disease)and extraintestinal diseases (diabetes type 1,food allergies,autoimmune diseases).Additionally,intestinal TJs may be secondarily disrupted during the course of diverse diseases,subsequently allowing the bacterial translocation phenomenon and promoting the systemic inflammatory response,which is often associated with clinical deterioration.The major questions in the field are highlighted.展开更多
The tight junction (TJ) is a critical cellular component for maintenance of tissue integrity, cellular interactions and cell-cell communications, and physiologically functions as the "great wall" against ext...The tight junction (TJ) is a critical cellular component for maintenance of tissue integrity, cellular interactions and cell-cell communications, and physiologically functions as the "great wall" against external agents and the surrounding hostile environment. During the host-pathogen evolution, viruses somehow found the key to unlock the gate for their entry into cells and to exploit and exhaust the host cells. In the liver, an array of TJ molecules is localized along the bile canaliculi forming the blood-biliary barrier, where they play pivotal roles in paracellular permeability, bile secretion, and cell polarity. In pathology, certain hepatic TJ molecules mediate virus entry causing hepatitis infection; deregulation and functional abnormality of the TJ have also been implicated in triggering liver cancer development and metastasis. All these findings shed new insights on the understanding of hepatic TJs in the development of liver disease and provide new clues for potential intervention.展开更多
Pancreatic cancer continues to be a leading cause of cancer-related death worldwide and there is an urgent need to develop novel diagnostic and therapeutic strategies to reduce the mortality of patients with this dise...Pancreatic cancer continues to be a leading cause of cancer-related death worldwide and there is an urgent need to develop novel diagnostic and therapeutic strategies to reduce the mortality of patients with this disease. In pancreatic cancer, some tight junction proteins, including claudins, are abnormally regulated and therefore are promising molecular targets for diagnosis, prognosis and therapy. Claudin-4 and-18 are overexpressed in human pancreatic cancer and its precursor lesions. Claudin-4 is a high affinity receptor of Clostridium perfringens enterotoxin(CPE). The cytotoxic effects of CPE and monoclonal antibodies against claudin-4 are useful as novel therapeutic tools for pancreatic cancer. Claudin-18 could be a putative marker and therapeutic target with prognostic implications for patients with pancreatic cancer. Claudin-1,-7, tricellulin and marvelD3 are involved in epithelial to mesenchymal transition(EMT) of pancreatic cancer cells and thus might be useful as biomarkers during disease. Protein kinase C is closely related to EMT of pancreatic cancer and regulates tight junctions of normal human pancreatic duct epithelial cells and the cancer cells. This review focuses on the regulation of tight junctions via protein kinase C during EMT in human pancreatic cancer for the purpose of developing new diagnostic and therapeutic modalities for pancreatic cancer.展开更多
Two-dimensional(2D) magnetic crystals have attracted great attention due to their emerging new physical phenomena. They provide ideal platforms to study the fundamental physics of magnetism in low dimensions. In this ...Two-dimensional(2D) magnetic crystals have attracted great attention due to their emerging new physical phenomena. They provide ideal platforms to study the fundamental physics of magnetism in low dimensions. In this research,magnetic tunneling junctions(MTJs) based on XSe2(X = Mn, V) with room-temperature ferromagnetism were studied using first-principles calculations. A large tunneling magnetoresistance(TMR) of 725.07% was obtained in the MTJs based on monolayer MnSe2. Several schemes were proposed to improve the TMR of these devices. Moreover, the results of our non-equilibrium transport calculations showed that the large TMR was maintained in these devices under a finite bias.The transmission spectrum was analyzed according to the orbital components and the electronic structure of the monolayer XSe2(X = Mn, V). The results in this paper demonstrated that the MTJs based on a 2D ferromagnet with room-temperature ferromagnetism exhibited reliable performance. Therefore, such devices show the possibility for potential applications in spintronics.展开更多
Objective:In this study,the influence of puerarin,paeoniflorin,and menthol on the structure and barrier function of tight junctions(TJs)in MadineDarby canine kidney epithelial(MDCK)and MDCK-multi-drug resistance 1(MDR...Objective:In this study,the influence of puerarin,paeoniflorin,and menthol on the structure and barrier function of tight junctions(TJs)in MadineDarby canine kidney epithelial(MDCK)and MDCK-multi-drug resistance 1(MDR1)cells was evaluated to determine the mechanisms by which the drugs cross the bloodebrain barrier(BBB).Method:Cells were treated with puerarin,paeoniflorin,and menthol followed by immunohistochemical staining with occludin,claudin-1,and F-actin.The cells were then observed using laser-scanning confocal microscopy.Average optical density(AOD)of the immunofluorescence images of the proteins were analyzed using ImageJ software while Transepithelial electrical resistance(TEER)was measured using an epithelial voltohmmeter.Results:Confocal microscopy revealed that puerarin-and paeoniflorin-treated tight junction proteins were conspicuous while menthol suppressed their expression.Correspondingly,AOD values of cells treated with puerarin or paeoniflorin,or both showed no difference compared to the control group(P>.05)while the menthol group value was downregulated.In 3 h,TEER of cells not treated with menthol were similar to the control group,while treatment with menthol significantly decreased TEER value(P<.05).In addition,application of menthol decreased TEER in MDCK cells earlier than in MDCK-MDR1 cells.Conclusion:Menthol but not puerarin and paeoniflorin may enhance paracellular transport and improve drug penetration of the BBB by disrupting the structure and,thereby,weakening the barrier function of TJs.展开更多
To study the influence of CoFeB/MgO interface on tunneling magnetoresistance(TMR),different structures of magnetic tunnel junctions(MTJs) are successfully prepared by the magnetron sputtering technique and characteriz...To study the influence of CoFeB/MgO interface on tunneling magnetoresistance(TMR),different structures of magnetic tunnel junctions(MTJs) are successfully prepared by the magnetron sputtering technique and characterized by atomic force microscopy,a physical property measurement system,x-ray photoelectron spectroscopy,and transmission electron microscopy.The experimental results show that TMR of the CoFeB/Mg/MgO/CoFeB structure is evidently improved in comparison with the CoFeB/MgO/CoFeB structure because the inserted Mg layer prevents Fe-oxide formation at the CoFeB/MgO interface,which occurs in CoFeB/MgO/CoFeB MTJs.The inherent properties of the CoFeB/MgO/CoFeB,CoFeB/Fe-oxide/MgO/CoFeB and CoFeB/Mg/MgO/CoFeB MTJs are simulated by using the theories of density functions and non-equilibrium Green functions.The simulated results demonstrate that TMR of CoFeB/Fe-oxide/MgO/CoFeB MTJs is severely decreased and is only half the value of the CoFeB/Mg/MgO/CoFeB MTJs.Based on the experimental results and theoretical analysis,it is believed that in CoFeB/MgO/CoFeB MTJs,the interface oxidation of the CoFeB layer is the main reason to cause a remarkable reduction of TMR,and the inserted Mg layer may play an important role in protecting Fe atoms from oxidation,and then increasing TMR.展开更多
For convenient and efficient verification of the magnetoresistance effect in graphene spintronic devices, vertical magnetic junctions with monolayer graphene sandwiched between two Ni Fe electrodes are fabricated by a...For convenient and efficient verification of the magnetoresistance effect in graphene spintronic devices, vertical magnetic junctions with monolayer graphene sandwiched between two Ni Fe electrodes are fabricated by a relatively simple way of transferring CVD graphene onto the bottom ferromagnetic stripes. The anisotropic magnetoresistance contribution is excluded by the experimental result of magnetoresistance(MR) ratio dependence on the magnetic field direction. The spin-dependent transport measurement reveals two distinct resistance states switching under an in-plane sweeping magnetic field. A magnetoresistance ratio of about 0.17 % is obtained at room temperature and it shows a typical monotonic downward trend with the bias current increasing. This bias dependence of MR further verifies that the spin transport signal in our device is not from the anisotropic magnetoresistance. Meanwhile, the I–V curve is found to manifest a linear behavior, which demonstrates the Ohmic contacts at the interface and the metallic transport characteristic of vertical graphene junction.展开更多
Temperature dependence of tunnel magnetoresistance (TMR) ratio. resistance, and coercivity from 4.2 K to room temperature (RT), applied dc bias voltage dependence of the TMR ratio and resistances at 4.2 K and RT. tunn...Temperature dependence of tunnel magnetoresistance (TMR) ratio. resistance, and coercivity from 4.2 K to room temperature (RT), applied dc bias voltage dependence of the TMR ratio and resistances at 4.2 K and RT. tunnel current I and dynamic conductance dI/dV as functions of the dc bias voltage at 4.2 K, and inelastic electron tunneling (IET) spectroscopy, d2I/dV2 versus V, at 4.2 K for a tunnel junction of Ta(5 nm)/Ni79 Fe21 (25 nm)/lr22 Mn78(12 nm)/Co75 Fe25(4 nm)/ Al(0.8 um)-oxide/Co75Fe25(4 nm)/Ni79Fe21(25 nm)/Ta(5 um ) were systematically investigated High TMR ratio of 59.2% at 4.2 K and 41.3% at RT were observed for this junction after annealing at 275’C for an hour. The temperature dependence of TMR ratio and resistances from 4.2 to 300 K at 1.0 mV bias and the dc bias voltage dependence of TMR ratio at 4.2 K from 0 to 80 mV can be evaluated by a comparison of self-consistent calculations with the experimental data based on the magnon-assisted inelastic excitation model and theory. An anisotropic wavelength cutoff energy of spin-wave spectrum in magnetic tunnel junctions (MTJs) was suggested, which is necessary for self-consistent calculations, based on a series of IET spectra observed in the MTJs.展开更多
Switching current distributions of an Nb/Al-AlO x /Nb Josephson junction are measured in a temperature range from 25 mK to 800 mK.We analyse the phase escape properties by using the theory of Larkin and Ovchinnikov (L...Switching current distributions of an Nb/Al-AlO x /Nb Josephson junction are measured in a temperature range from 25 mK to 800 mK.We analyse the phase escape properties by using the theory of Larkin and Ovchinnikov (LO) which takes discrete energy levels into account.Our results show that the phase escape can be well described by the LO approach for temperatures near and below the crossover from thermal activation to macroscopic quantum tunneling.These results are helpful for further study of macroscopic quantum phenomena in Josephson junctions where discrete energy levels need to be considered.展开更多
Modulated electronic state due to the layered crystal structures brings about moderate anisotropy of superconductivity in the iron-based superconductors and thus Abrikosov vortices are expected in the mixed state.Howe...Modulated electronic state due to the layered crystal structures brings about moderate anisotropy of superconductivity in the iron-based superconductors and thus Abrikosov vortices are expected in the mixed state.However,based on the angular and temperature dependent transport measurements in iron-based superconductor Ca_(10)(Pt_(3)As_(8))((Fe_(0.9)Pt_(0.1))_(2)As_(2))_(5) with Tc(≌)12 K,we find clear evidences of a crossover from Abrikosov vortices to Josephson vortices at a crossover temperature T*(≌)7 K,when the applied magnetic field is parallel to the superconducting FeAs layers,i.e.,the angle between the magnetic field and the FeAs layers θ=0°.This crossover to Josephson vortices is demonstrated by an abnormal decrease(increase)of the critical current(flux-flow resistance)below T*,in contrast to the increase(decrease)of the critical current(flux-flow resistance)above T* expected for Abrikosov vortices.Furthermore,when θ is larger than 0.5°,the flux-flow resistance and critical current have no anomalous behaviors across T*.These anomalous behaviors can be understood in terms of the distinct transition from the well-pinned Abrikosov vortices to the weakly-pinned Josephson vortices upon cooling,when the coherent length perpendicular to the FeAs layers ξ⊥ becomes shorter than half of the interlayer distance d/2.These experimental findings indicate the existence of intrinsic Josephson junctions below T* and thus quasi-two-dimensional superconductivity in Ca10(Pt3As8)((Fe0.9Pt0.1)2As2)5,similar to those in the cuprate superconductors.展开更多
The spin-dependent Andreev reflection is investigated theoretically by analyzing the electronic transport in a thin-film topological insulator(TI)ferromagnet/superconductor(FM/SC)junction.The tunneling conductance and...The spin-dependent Andreev reflection is investigated theoretically by analyzing the electronic transport in a thin-film topological insulator(TI)ferromagnet/superconductor(FM/SC)junction.The tunneling conductance and shot noise are calculated based on the Dirac-Bogoliubov-de Gennes equation and Blonder-Tinkham-Klapwijk theory.It is found that the magnetic gap in ferromagnet can enhance the Andreev retro-reflection but suppress the specular Andreev reflection.The gate potential applied to the electrode on top of superconductor can enhance the two types of reflections.There is a transition between the two types of reflections at which both the tunneling conductance and differential shot noise become zero.These results provide a method to realize and detect experimentally the intra-band specular Andreev reflection in thin film TI-based FM/SC structures.展开更多
We focus on two new 2D materials, i.e., monolayer and bilayer silicon phosphides(Si_1 P_1). Based on the elasticscattering Green's function, the electronic-transport properties of two-dimensional monolayer and bil...We focus on two new 2D materials, i.e., monolayer and bilayer silicon phosphides(Si_1 P_1). Based on the elasticscattering Green's function, the electronic-transport properties of two-dimensional monolayer and bilayer AuSi_1 P_1-Au molecular junctions are studied. It is found that their bandgaps are narrow(0.16 eV for a monolayer molecular junction and 0.26 eV for a bilayer molecular junction). Moreover, the calculated current-voltage characteristics indicate that the monolayer molecular junction provides constant output current(20nA) over a wide voltage range, and the bilayer molecular junction provides higher current(42nA).展开更多
Tight junctions are mainly formed by two types of proteins;claudins and occludin, both of which are fundamental to maintain the integrity and barrier function of the intestinal epithelium. This barrier function allows...Tight junctions are mainly formed by two types of proteins;claudins and occludin, both of which are fundamental to maintain the integrity and barrier function of the intestinal epithelium. This barrier function allows for the absorption of nutrients, mainly by transcytosis;however, in birds, 90% of the substances are absorbed by paracellular mechanisms. Despite this, claudins present in th<span style="font-family:Verdana;"></span><span style="font-family:;" "="">e different parts of the intestinal tract of adult chickens are not known, much less their functional role. This study aimed to determine the presence of mRNA of claudins 1, 2, 3, 5, 10, 12, 16 and occludin, in the different regions of the intestine (duodenum, jejunum, ileum, cecum, and rectum) in chickens (<i>Gallus gallus domesticus</i>) through RT-PCR. To meet this goal, 7 weeks old roosters destined for slaughter and chicken embryos of 16 days of incubation (positive control) were used. For all the processed samples, amplicons of the expected size were obtained;claudin 1 (662 pb), claudin 2 (162 pb), claudin 3 (185 pb), claudin 5 (224 pb), claudin 10 (687 pb), claudin 12 (738 pb), claudin 16 (191 pb) and occludin (430 pb). To corroborate these findings, obtained amplicons were sequenced and, subsequently, a basic alignment was performed on the NCBI, obtaining a correlation of 100% with the original sequences in all analyzed samples. To our knowledge, the present work represents the first written report regarding the presence of mRNA of the main proteins involved in tight junction formation throughout the intestinal tract of domestic chickens of 7 weeks of age. These findings will allow elucidating the specific function of each of the reported proteins in the process of paracellular absorption in chickens.</span>展开更多
Multi Tunnel Junctions (MTJs) have attracted much attention recently in the fields of Single-Electron Transistor (SET) and Single-Electron Memory (SEM). In this paper, we investigate a nano-device structure using a tw...Multi Tunnel Junctions (MTJs) have attracted much attention recently in the fields of Single-Electron Transistor (SET) and Single-Electron Memory (SEM). In this paper, we investigate a nano-device structure using a two one dimensional array MTJs connected to the basic Single Electron Circuits, in order to analyze the impact of physical parameters on the performances and application of this structure. The device generates can operate at room temperature. The simulation of single-electron circuit demonstrates with Monte Carlo simulator, SIMON.展开更多
Preliminary results of a study are reported here investigating mesoscopic tunnel junctions irradiated with coherent low-intensity (-50 to -10 dB) pulsed microwave RF fields at moderately low (LN2) temperatures. Quantu...Preliminary results of a study are reported here investigating mesoscopic tunnel junctions irradiated with coherent low-intensity (-50 to -10 dB) pulsed microwave RF fields at moderately low (LN2) temperatures. Quantum tunneling of electrons was observed through fabricated mesoscale gap junctions as a result of coherent irradiating fields at low temperatures around 77 - 100 K. The tunneling current was seen as a result of applied microwave fields across the junctions, distinguishable from shot noise and resistance effects. The form of tunneling behavior does not lead to any conductance quantization effects which could manifest the junction as a Quantum Point Contact (QPC), hence it is surmised that the phenomenon is purely low intensity RF field-induced tunneling of electrons across the mesoscale junctions at low temperatures.展开更多
Spin dynamics in several different types of ferromagnetic metal(FM)/10-nm-thick n-type GaAs quantum well(QW) junctions is studied by means of time-resolved Kerr rotation measurements. Compared with the MnGa/insitu dop...Spin dynamics in several different types of ferromagnetic metal(FM)/10-nm-thick n-type GaAs quantum well(QW) junctions is studied by means of time-resolved Kerr rotation measurements. Compared with the MnGa/insitu doped 10-nm-thick n-type GaAs QW junction, the spin lifetime of the MnGa/modulation-doped 10-nm-thick n-type GaAs QW junction is shorter by a factor of 5,consistent with the D'yakonov-Pcrel' spin relaxation mechanism. Meanwhile, compared with the spin lifetime of the MnAs/in-situ doped 10-nm-thick n-type GaAs QW junction, the MnGa/in-situ doped 10-nm-thick n-type GaAs QW junction is of a spin lifetime longer by a factor of 4.2. The later observation is well explained by the Rashba effect in the presence of structure inversion asymmetry, which acts directly on photo-excited eleetron spins. We demonstrate that MnGa-like FM/in-situ doped 10-nm-thick n-type GaAs QW junctions, which possess relatively low interfacial potential barriers, are able to provide long spin lifetimes.展开更多
文摘With an extensive range of distinctive features at nano meter-scale thicknesses,two-dimensional(2D)materials drawn the attention of the scientific community.Despite tremendous advancements in exploratory research on 2D materials,knowledge of 2D electrical transport and carrier dynamics still in its infancy.Thus,here we highlighted the electrical characteristics of 2D materials with electronic band structure,electronic transport,dielectric constant,carriers mobility.The atomic thinness of 2D materials makes substantially scaled field-effect transistors(FETs)with reduced short-channel effects conceivable,even though strong carrier mobility required for high performance,low-voltage device operations.We also discussed here about factors affecting 2D materials which easily enhanced the activity of those materials for various applications.Presently,Those 2D materials used in state-of-the-art electrical and optoelectronic devices because of the extensive nature of their electronic band structure.2D materials offer unprecedented freedom for the design of novel p-n junction device topologies in contrast to conventional bulk semiconductors.We also,describe the numerous 2D p-n junctions,such as homo junction and hetero junction including mixed dimensional junctions.Finally,we talked about the problems and potential for the future.
基金supported by the National Key Research and Development Program of China (2017YFE0131500, 2022YFB2802801)the National Natural Science Foundation of China (61834008, U21A20493)+1 种基金the Key Research and Development Program of Jiangsu Province (BE2020004, BE2021008-1)the Suzhou Key Laboratory of New-type Laser Display Technology (SZS2022007)
文摘The InGaN films and GaN/InGaN/GaN tunnel junctions(TJs)were grown on GaN templates with plasma-assisted molecular beam epitaxy.As the In content increases,the quality of InGaN films grown on GaN templates decreases and the surface roughness of the samples increases.V-pits and trench defects were not found in the AFM images.p++-GaN/InGaN/n++-GaN TJs were investigated for various In content,InGaN thicknesses and doping concentration in the InGaN insert layer.The InGaN insert layer can promote good interband tunneling in GaN/InGaN/GaN TJ and significantly reduce operating voltage when doping is sufficiently high.The current density increases with increasing In content for the 3 nm InGaN insert layer,which is achieved by reducing the depletion zone width and the height of the potential barrier.At a forward current density of 500 A/cm^(2),the measured voltage was 4.31 V and the differential resistance was measured to be 3.75×10^(−3)Ω·cm^(2)for the device with a 3 nm p++-In_(0.35)Ga_(0.65)N insert layer.When the thickness of the In_(0.35)Ga_(0.65)N layer is closer to the“balanced”thickness,the TJ current density is higher.If the thickness is too high or too low,the width of the depletion zone will increase and the current density will decrease.The undoped InGaN layer has a better performance than n-type doping in the TJ.Polarization-engineered tunnel junctions can enhance the functionality and performance of electronic and optoelectronic devices.
基金the following funds:the National Key R&D Program of China(Project No.2017YFD0502200)the National Natural Science Foundation of China(Project No.31960721)the National Natural Science Foundation of China(Project No.31873034)。
文摘Background:Bacillus cereus is an important pathogen that causes human food poisoning,specifically diarrhea and vomiting.B.cereus can also induce mastitis in dairy cows and has a strong survival ability in milk,as it cannot be inactivated by high-temperature short-time pasteurization.Therefore,B.cereus can enter the market through pasteurized milk and other dairy products,imposing enormous hidden dangers on food safety and human health.Results:In this study,B.cereus 2101(BC)was isolated from milk samples of cows with mastitis.BC grew rapidly with strong hemolysis,making it difficult to prevent mastitis and ensure food security.MAC-T cells were treated with BC and/or Lactobacillus rhamnosus GR-1(LGR-1).Pretreatment with LGR-1 protected the integrity of tight junctions and the expression of zonula occludens-1(ZO-1)and occludin destroyed by BC.Furthermore,LGR-1 pretreatment reduced the expression of NOD-like receptor family member pyrin domain-containing protein 3(NLRP3),caspase recruitment and activation domain(ASC),Caspase-1 p20,gasdermin D(GSDMD)p30,inflammatory factors(interleukin(IL)-1βand IL-18),and cell death induced by BC.Moreover,LGR-1 pretreatment reduced NLRP3 inflammasome activity and increased expressions of ZO-1 and occludin induced by lipopolysaccharides(LPS)+ATP stimulation.MAC-T cells were transfected with NLRP3 si RNA or MCC950 and/or treated with BC and/or LGR-1.NLRP3-si RNA transfection and MCC950 attenuated BC-induced NLRP3 inflammasome activity.Expression of inflammatory cytokines and cell death suggested that the inflammatory pathway might play an important role in the induction of the NLRP3 inflammasome by BC and the protection of LGR-1.Conclusions:These results suggest that LGR-1 might be a probiotic alternative to antibiotics and could be administered to prevent mastitis in dairy cows,thus ensuring food security.
基金supported by National Natural Science Foundation of China(Nos.21971143 and 21805165)the Hubei Provincial Department of Education(D20201207)and 111 Project(D20015).
文摘Photocatalytic water splitting on noble metal-free photocatalysts for H_(2) generation is a promising but challenging approach to realize solar-to-chemical energy conversion.In this study,Mo/Mo_(2)C nanoparticles anchored carbon layer(Mo/Mo_(2)C@C)was obtained by a one-step in-situ phase transition approach and developed for the first time as a photothermal cocatalyst to enhance the activity of ZnIn_(2)S_(4)photocatalyst.Mo/Mo_(2)C@C nanosheet exhibits strong absorption in the full spectrum region and excellent photo-thermal conversion ability,which generates heat to improve the reaction temperature and accelerate the reaction kinetics.Moreover,metallic Mo/Mo_(2)C@C couples with ZnIn_(2)S_(4)to form ZnIn_(2)S_(4)-Mo/Mo_(2)C@C Schottky junction(denoted as ZMM),which prevents the electrons back transfer and restrains the charge recombination.In addition,conductive carbon with strong interfacial interaction serves as a fast charge transport bridge.Consequently,the optimized ZMM-0.2 junction exhibits an H2 evolution rate of 1031.07μmol g^(-1)h^-(1),which is 41 and 4.3 times higher than bare ZnIn_(2)S_(4)and ZnIn_(2)S_(4)-Mo2C,respectively.By designing novel photothermal cocatalysts,our work will provide a new guidance for designing efficient photocatalysts.
文摘Tight junctions(TJs)are structures between cells where cells appear in the closest possible contact.They are responsible for sealing compartments when epithelial sheets are generated.They regulate the permeability of ions,(macro)molecules and cells via the paracellular pathway.Their structure at the electron microscopic level has been well known since the 1970s;however,only recently has their macromolecular composition been revealed.This review first examines the major macromolecular components of the TJs(occludin,claudins,junctional adhesion molecule and tricellulin)and then the associated macromolecules at the intracellular plaque[zonula occludens(ZO)-1,ZO-2,ZO-3,AF-6,cingulin,7H6].Emphasis is given to their interactions in order to begin to understand the mode of assembly of TJs.The functional significance of TJs is detailed and several mechanisms and factors involved are discussed briefly.Emphasis is given to the role of intestinal TJs and the alterations observed or speculated in diverse disease states.Specifically,intestinal TJs may exert a pathogenetic role in intestinal(inflammatory bowel disease,celiac disease)and extraintestinal diseases (diabetes type 1,food allergies,autoimmune diseases).Additionally,intestinal TJs may be secondarily disrupted during the course of diverse diseases,subsequently allowing the bacterial translocation phenomenon and promoting the systemic inflammatory response,which is often associated with clinical deterioration.The major questions in the field are highlighted.
基金Supported by A GRF Grant from the Research Grants Council of Hong Kong to Luk JM,No.771607M
文摘The tight junction (TJ) is a critical cellular component for maintenance of tissue integrity, cellular interactions and cell-cell communications, and physiologically functions as the "great wall" against external agents and the surrounding hostile environment. During the host-pathogen evolution, viruses somehow found the key to unlock the gate for their entry into cells and to exploit and exhaust the host cells. In the liver, an array of TJ molecules is localized along the bile canaliculi forming the blood-biliary barrier, where they play pivotal roles in paracellular permeability, bile secretion, and cell polarity. In pathology, certain hepatic TJ molecules mediate virus entry causing hepatitis infection; deregulation and functional abnormality of the TJ have also been implicated in triggering liver cancer development and metastasis. All these findings shed new insights on the understanding of hepatic TJs in the development of liver disease and provide new clues for potential intervention.
基金Supported by Ministry of Education,Culture,Sports Science,and Technology,and the Ministry of Health,Labour and Welfare of Japan
文摘Pancreatic cancer continues to be a leading cause of cancer-related death worldwide and there is an urgent need to develop novel diagnostic and therapeutic strategies to reduce the mortality of patients with this disease. In pancreatic cancer, some tight junction proteins, including claudins, are abnormally regulated and therefore are promising molecular targets for diagnosis, prognosis and therapy. Claudin-4 and-18 are overexpressed in human pancreatic cancer and its precursor lesions. Claudin-4 is a high affinity receptor of Clostridium perfringens enterotoxin(CPE). The cytotoxic effects of CPE and monoclonal antibodies against claudin-4 are useful as novel therapeutic tools for pancreatic cancer. Claudin-18 could be a putative marker and therapeutic target with prognostic implications for patients with pancreatic cancer. Claudin-1,-7, tricellulin and marvelD3 are involved in epithelial to mesenchymal transition(EMT) of pancreatic cancer cells and thus might be useful as biomarkers during disease. Protein kinase C is closely related to EMT of pancreatic cancer and regulates tight junctions of normal human pancreatic duct epithelial cells and the cancer cells. This review focuses on the regulation of tight junctions via protein kinase C during EMT in human pancreatic cancer for the purpose of developing new diagnostic and therapeutic modalities for pancreatic cancer.
基金Project supported by the National Natural Science Foundation of China(Grant Nos.61571415 and 61622406)the National Key Research and Development Program of China(Grant No.2017YFA0207500)+1 种基金the Strategic Priority Research Program of the Chinese Academy of Sciences(Grant No.XDB30000000)Beijing Academy of Quantum Information Sciences,China(Grant No.Y18G04)
文摘Two-dimensional(2D) magnetic crystals have attracted great attention due to their emerging new physical phenomena. They provide ideal platforms to study the fundamental physics of magnetism in low dimensions. In this research,magnetic tunneling junctions(MTJs) based on XSe2(X = Mn, V) with room-temperature ferromagnetism were studied using first-principles calculations. A large tunneling magnetoresistance(TMR) of 725.07% was obtained in the MTJs based on monolayer MnSe2. Several schemes were proposed to improve the TMR of these devices. Moreover, the results of our non-equilibrium transport calculations showed that the large TMR was maintained in these devices under a finite bias.The transmission spectrum was analyzed according to the orbital components and the electronic structure of the monolayer XSe2(X = Mn, V). The results in this paper demonstrated that the MTJs based on a 2D ferromagnet with room-temperature ferromagnetism exhibited reliable performance. Therefore, such devices show the possibility for potential applications in spintronics.
文摘Objective:In this study,the influence of puerarin,paeoniflorin,and menthol on the structure and barrier function of tight junctions(TJs)in MadineDarby canine kidney epithelial(MDCK)and MDCK-multi-drug resistance 1(MDR1)cells was evaluated to determine the mechanisms by which the drugs cross the bloodebrain barrier(BBB).Method:Cells were treated with puerarin,paeoniflorin,and menthol followed by immunohistochemical staining with occludin,claudin-1,and F-actin.The cells were then observed using laser-scanning confocal microscopy.Average optical density(AOD)of the immunofluorescence images of the proteins were analyzed using ImageJ software while Transepithelial electrical resistance(TEER)was measured using an epithelial voltohmmeter.Results:Confocal microscopy revealed that puerarin-and paeoniflorin-treated tight junction proteins were conspicuous while menthol suppressed their expression.Correspondingly,AOD values of cells treated with puerarin or paeoniflorin,or both showed no difference compared to the control group(P>.05)while the menthol group value was downregulated.In 3 h,TEER of cells not treated with menthol were similar to the control group,while treatment with menthol significantly decreased TEER value(P<.05).In addition,application of menthol decreased TEER in MDCK cells earlier than in MDCK-MDR1 cells.Conclusion:Menthol but not puerarin and paeoniflorin may enhance paracellular transport and improve drug penetration of the BBB by disrupting the structure and,thereby,weakening the barrier function of TJs.
基金Supported by the National Defense Advance Research Foundation under Grant No 9140A08XXXXXX0DZ106the Basic Research Program of Ministry of Education of China under Grant No JY10000925005+2 种基金the Scientific Research Program Funded by Shaanxi Provincial Education Department under Grant No 11JK0912the Scientific Research Foundation of Xi'an University of Science and Technology under Grant No 2010011the Doctoral Research Startup Fund of Xi'an University of Science and Technology under Grant No 2010QDJ029
文摘To study the influence of CoFeB/MgO interface on tunneling magnetoresistance(TMR),different structures of magnetic tunnel junctions(MTJs) are successfully prepared by the magnetron sputtering technique and characterized by atomic force microscopy,a physical property measurement system,x-ray photoelectron spectroscopy,and transmission electron microscopy.The experimental results show that TMR of the CoFeB/Mg/MgO/CoFeB structure is evidently improved in comparison with the CoFeB/MgO/CoFeB structure because the inserted Mg layer prevents Fe-oxide formation at the CoFeB/MgO interface,which occurs in CoFeB/MgO/CoFeB MTJs.The inherent properties of the CoFeB/MgO/CoFeB,CoFeB/Fe-oxide/MgO/CoFeB and CoFeB/Mg/MgO/CoFeB MTJs are simulated by using the theories of density functions and non-equilibrium Green functions.The simulated results demonstrate that TMR of CoFeB/Fe-oxide/MgO/CoFeB MTJs is severely decreased and is only half the value of the CoFeB/Mg/MgO/CoFeB MTJs.Based on the experimental results and theoretical analysis,it is believed that in CoFeB/MgO/CoFeB MTJs,the interface oxidation of the CoFeB layer is the main reason to cause a remarkable reduction of TMR,and the inserted Mg layer may play an important role in protecting Fe atoms from oxidation,and then increasing TMR.
基金Project supported by the National Natural Science Foundation of China (Grant No. 62004223)the Open Research Fund Program of the State Key Laboratory of LowDimensional Quantum Physics, China (Grant No. KF202012)。
文摘For convenient and efficient verification of the magnetoresistance effect in graphene spintronic devices, vertical magnetic junctions with monolayer graphene sandwiched between two Ni Fe electrodes are fabricated by a relatively simple way of transferring CVD graphene onto the bottom ferromagnetic stripes. The anisotropic magnetoresistance contribution is excluded by the experimental result of magnetoresistance(MR) ratio dependence on the magnetic field direction. The spin-dependent transport measurement reveals two distinct resistance states switching under an in-plane sweeping magnetic field. A magnetoresistance ratio of about 0.17 % is obtained at room temperature and it shows a typical monotonic downward trend with the bias current increasing. This bias dependence of MR further verifies that the spin transport signal in our device is not from the anisotropic magnetoresistance. Meanwhile, the I–V curve is found to manifest a linear behavior, which demonstrates the Ohmic contacts at the interface and the metallic transport characteristic of vertical graphene junction.
文摘Temperature dependence of tunnel magnetoresistance (TMR) ratio. resistance, and coercivity from 4.2 K to room temperature (RT), applied dc bias voltage dependence of the TMR ratio and resistances at 4.2 K and RT. tunnel current I and dynamic conductance dI/dV as functions of the dc bias voltage at 4.2 K, and inelastic electron tunneling (IET) spectroscopy, d2I/dV2 versus V, at 4.2 K for a tunnel junction of Ta(5 nm)/Ni79 Fe21 (25 nm)/lr22 Mn78(12 nm)/Co75 Fe25(4 nm)/ Al(0.8 um)-oxide/Co75Fe25(4 nm)/Ni79Fe21(25 nm)/Ta(5 um ) were systematically investigated High TMR ratio of 59.2% at 4.2 K and 41.3% at RT were observed for this junction after annealing at 275’C for an hour. The temperature dependence of TMR ratio and resistances from 4.2 to 300 K at 1.0 mV bias and the dc bias voltage dependence of TMR ratio at 4.2 K from 0 to 80 mV can be evaluated by a comparison of self-consistent calculations with the experimental data based on the magnon-assisted inelastic excitation model and theory. An anisotropic wavelength cutoff energy of spin-wave spectrum in magnetic tunnel junctions (MTJs) was suggested, which is necessary for self-consistent calculations, based on a series of IET spectra observed in the MTJs.
基金Project supported by the National Natural Science Foundation of China (Grant Nos.10534060 and 10874231)National Basic Research Program of China (Grant Nos.2006CB601007,2006CB921107,and 2009CB929102)
文摘Switching current distributions of an Nb/Al-AlO x /Nb Josephson junction are measured in a temperature range from 25 mK to 800 mK.We analyse the phase escape properties by using the theory of Larkin and Ovchinnikov (LO) which takes discrete energy levels into account.Our results show that the phase escape can be well described by the LO approach for temperatures near and below the crossover from thermal activation to macroscopic quantum tunneling.These results are helpful for further study of macroscopic quantum phenomena in Josephson junctions where discrete energy levels need to be considered.
基金Project supported by the National Key Research and Development Program of China(Grant No.2017YFA0302903)the National Natural Science Foundation of China(Grant No.11974412).
文摘Modulated electronic state due to the layered crystal structures brings about moderate anisotropy of superconductivity in the iron-based superconductors and thus Abrikosov vortices are expected in the mixed state.However,based on the angular and temperature dependent transport measurements in iron-based superconductor Ca_(10)(Pt_(3)As_(8))((Fe_(0.9)Pt_(0.1))_(2)As_(2))_(5) with Tc(≌)12 K,we find clear evidences of a crossover from Abrikosov vortices to Josephson vortices at a crossover temperature T*(≌)7 K,when the applied magnetic field is parallel to the superconducting FeAs layers,i.e.,the angle between the magnetic field and the FeAs layers θ=0°.This crossover to Josephson vortices is demonstrated by an abnormal decrease(increase)of the critical current(flux-flow resistance)below T*,in contrast to the increase(decrease)of the critical current(flux-flow resistance)above T* expected for Abrikosov vortices.Furthermore,when θ is larger than 0.5°,the flux-flow resistance and critical current have no anomalous behaviors across T*.These anomalous behaviors can be understood in terms of the distinct transition from the well-pinned Abrikosov vortices to the weakly-pinned Josephson vortices upon cooling,when the coherent length perpendicular to the FeAs layers ξ⊥ becomes shorter than half of the interlayer distance d/2.These experimental findings indicate the existence of intrinsic Josephson junctions below T* and thus quasi-two-dimensional superconductivity in Ca10(Pt3As8)((Fe0.9Pt0.1)2As2)5,similar to those in the cuprate superconductors.
文摘The spin-dependent Andreev reflection is investigated theoretically by analyzing the electronic transport in a thin-film topological insulator(TI)ferromagnet/superconductor(FM/SC)junction.The tunneling conductance and shot noise are calculated based on the Dirac-Bogoliubov-de Gennes equation and Blonder-Tinkham-Klapwijk theory.It is found that the magnetic gap in ferromagnet can enhance the Andreev retro-reflection but suppress the specular Andreev reflection.The gate potential applied to the electrode on top of superconductor can enhance the two types of reflections.There is a transition between the two types of reflections at which both the tunneling conductance and differential shot noise become zero.These results provide a method to realize and detect experimentally the intra-band specular Andreev reflection in thin film TI-based FM/SC structures.
基金Supported by the National Natural Science Foundation of China under Grant No 11374033
文摘We focus on two new 2D materials, i.e., monolayer and bilayer silicon phosphides(Si_1 P_1). Based on the elasticscattering Green's function, the electronic-transport properties of two-dimensional monolayer and bilayer AuSi_1 P_1-Au molecular junctions are studied. It is found that their bandgaps are narrow(0.16 eV for a monolayer molecular junction and 0.26 eV for a bilayer molecular junction). Moreover, the calculated current-voltage characteristics indicate that the monolayer molecular junction provides constant output current(20nA) over a wide voltage range, and the bilayer molecular junction provides higher current(42nA).
文摘Tight junctions are mainly formed by two types of proteins;claudins and occludin, both of which are fundamental to maintain the integrity and barrier function of the intestinal epithelium. This barrier function allows for the absorption of nutrients, mainly by transcytosis;however, in birds, 90% of the substances are absorbed by paracellular mechanisms. Despite this, claudins present in th<span style="font-family:Verdana;"></span><span style="font-family:;" "="">e different parts of the intestinal tract of adult chickens are not known, much less their functional role. This study aimed to determine the presence of mRNA of claudins 1, 2, 3, 5, 10, 12, 16 and occludin, in the different regions of the intestine (duodenum, jejunum, ileum, cecum, and rectum) in chickens (<i>Gallus gallus domesticus</i>) through RT-PCR. To meet this goal, 7 weeks old roosters destined for slaughter and chicken embryos of 16 days of incubation (positive control) were used. For all the processed samples, amplicons of the expected size were obtained;claudin 1 (662 pb), claudin 2 (162 pb), claudin 3 (185 pb), claudin 5 (224 pb), claudin 10 (687 pb), claudin 12 (738 pb), claudin 16 (191 pb) and occludin (430 pb). To corroborate these findings, obtained amplicons were sequenced and, subsequently, a basic alignment was performed on the NCBI, obtaining a correlation of 100% with the original sequences in all analyzed samples. To our knowledge, the present work represents the first written report regarding the presence of mRNA of the main proteins involved in tight junction formation throughout the intestinal tract of domestic chickens of 7 weeks of age. These findings will allow elucidating the specific function of each of the reported proteins in the process of paracellular absorption in chickens.</span>
文摘Multi Tunnel Junctions (MTJs) have attracted much attention recently in the fields of Single-Electron Transistor (SET) and Single-Electron Memory (SEM). In this paper, we investigate a nano-device structure using a two one dimensional array MTJs connected to the basic Single Electron Circuits, in order to analyze the impact of physical parameters on the performances and application of this structure. The device generates can operate at room temperature. The simulation of single-electron circuit demonstrates with Monte Carlo simulator, SIMON.
文摘Preliminary results of a study are reported here investigating mesoscopic tunnel junctions irradiated with coherent low-intensity (-50 to -10 dB) pulsed microwave RF fields at moderately low (LN2) temperatures. Quantum tunneling of electrons was observed through fabricated mesoscale gap junctions as a result of coherent irradiating fields at low temperatures around 77 - 100 K. The tunneling current was seen as a result of applied microwave fields across the junctions, distinguishable from shot noise and resistance effects. The form of tunneling behavior does not lead to any conductance quantization effects which could manifest the junction as a Quantum Point Contact (QPC), hence it is surmised that the phenomenon is purely low intensity RF field-induced tunneling of electrons across the mesoscale junctions at low temperatures.
文摘Spin dynamics in several different types of ferromagnetic metal(FM)/10-nm-thick n-type GaAs quantum well(QW) junctions is studied by means of time-resolved Kerr rotation measurements. Compared with the MnGa/insitu doped 10-nm-thick n-type GaAs QW junction, the spin lifetime of the MnGa/modulation-doped 10-nm-thick n-type GaAs QW junction is shorter by a factor of 5,consistent with the D'yakonov-Pcrel' spin relaxation mechanism. Meanwhile, compared with the spin lifetime of the MnAs/in-situ doped 10-nm-thick n-type GaAs QW junction, the MnGa/in-situ doped 10-nm-thick n-type GaAs QW junction is of a spin lifetime longer by a factor of 4.2. The later observation is well explained by the Rashba effect in the presence of structure inversion asymmetry, which acts directly on photo-excited eleetron spins. We demonstrate that MnGa-like FM/in-situ doped 10-nm-thick n-type GaAs QW junctions, which possess relatively low interfacial potential barriers, are able to provide long spin lifetimes.
