Layered transition metal hydroxides show distinct advantages in separately co-catalyzing CO_(2)reduction and H_(2)O oxidation at the electron-accumulating and hole-accumulating sites of wrapped heterojunction photocat...Layered transition metal hydroxides show distinct advantages in separately co-catalyzing CO_(2)reduction and H_(2)O oxidation at the electron-accumulating and hole-accumulating sites of wrapped heterojunction photocatalysts,while concurrently preventing side reactions and photocorrosion on the semiconductor surface.Herein,Ni-Co bimetallic hydroxides with varying Ni/Co molar ratios(Ni_(x)Co_(1-x)(OH)_(2),x=1,0.75,0.5,0.25,and 0)were grown in situ on a model 2D/2D S-scheme heterojunction composed of Cu_(2)O nanosheets and Fe_(2)O_(3)nanoplates to form a series of Cu_(2)O/Fe_(2)O_(3)@Ni_(x)Co_(1-x)(OH)_(2)(CF@NiCo)photocatalysts.The combined experimental and theoretical investigation demonstrates that incorporating an appropriate amount of Co into Ni(OH)_(2)not only modulates the energy band structure of Ni_(x)Co_(1-x)(OH)_(2),balances the electron-and hole-trapping abilities of the bifunctional cocatalyst and maximizes the charge separation efficiency of the heterojunction,but also regulates the d-band center of Ni_(x)Co_(1-x)(OH)_(2),reinforcing the adsorption and activation of CO_(2)and H_(2)O on the cocatalyst surface and lowering the rate-limiting barriers in the CO_(2)-to-CO and H_(2)O-to-O_(2)conversion.Benefiting from the Ni-Co synergy,the redox reactions proceed stoichiometrically.The optimized CF@Ni_(0.75)Co_(0.25)achieves CO and O_(2)yields of 552.7 and 313.0μmol gcat^(-1)h^(-1),respectively,11.3/9.9,1.6/1.7,and 4.5/5.9-fold higher than those of CF,CF@Ni,and CF@Co.This study offers valuable insights into the design of bifunctional noble-metal-free cocatalysts for high-performance artificial photosynthesis.展开更多
To further enhance the yield and quality of kiwifruit and promote the sustainable development of the kiwifruit industry,this paper summarized the characteristics,damage sites,and control methods of major kiwifruit dis...To further enhance the yield and quality of kiwifruit and promote the sustainable development of the kiwifruit industry,this paper summarized the characteristics,damage sites,and control methods of major kiwifruit diseases and pests.It pointed out the main issues in current kiwifruit pest and disease management and proposed corresponding solutions.The prevention and control of kiwifruit pests should adhere to the principle of"prevention first,integrated management",and standardized planting modes should be implemented.In this process,priority should be given to agricultural,physical,and biological control methods to effectively reduce the use of chemical pesticides.展开更多
Climate conditions is an important factor affected the fragrant rice growth and development.In order to study the effects of different planting seasons on fragrant rice performance in South China,present study was con...Climate conditions is an important factor affected the fragrant rice growth and development.In order to study the effects of different planting seasons on fragrant rice performance in South China,present study was conducted with three planting seasons(early season(April to July),middle season(June to September)and late season(August to November))and three fragrant rice cultivars,‘Basmati-385’,‘Meixiangzhan-2’and‘Xiangyaxiangzhan’.The results showed that the highest grain yield and grain 2-acetyl-1-pyrroline(2-AP,key component of fragrant rice aroma)content were both recorded in late season treatment while the fragrant rice in middle season treatment produced the lowest grain yield,grain filling percentage,1000-grain weight and gain 2-AP content.The highest contents of precursors(proline,pyrroline-5-carboxylic acid and 1-pyrro-line)which related to 2-AP biosynthesis were recorded in late season treatment compared with early season treatment and middle season treatment.The highest activities of enzymes(proline dehydrogenase,pyrroline-5-carboxylic acid synthetase and ornithine transaminase)which involved in 2-AP biosynthesis were also observed in late season treatment.Moreover,the fragrant rice cultivars in late season possessed the lowest chalk rice rate,chalkiness as well as the highest brown rice rate,head rice and protein content.Thus,the optimal season for fragrant rice production in South China is the late season.展开更多
The industrial application of the Kaufman ion thruster in its arc stage is limited owing to the instability of the discharge pulse.Presently,a complete prediction model that can predict the discharge pulse in the high...The industrial application of the Kaufman ion thruster in its arc stage is limited owing to the instability of the discharge pulse.Presently,a complete prediction model that can predict the discharge pulse in the high-current stage does not exist.In this study,a complete prediction model for the pulse in the ion thruster is established using the zero-dimensional plasma discharge model and equivalent circuit model.The zero-dimensional plasma discharge model is used to obtain the corresponding plasma parameters by calculating the beam current,discharge current,voltage,and gas flow under actual working conditions.The input parameters of the equivalent circuit model are calculated using empirical formulae to acquire the estimated discharge waveforms.The pulse waveforms obtained using the model are found to be consistent with the experimental results.The model is used to evaluate the process of rapid changes in plasma density.Additionally,this model is employed to predict changes in the pulse waveforms when the volume of the discharge chamber and grid plate transmittance are changed.展开更多
A 4H-SiC power MOSFET with specific on-resistance of 3.4 mΩ·cm^2 and breakdown voltage exceeding 1.5 kV is designed and fabricated.Numerical simulations are carried out to optimize the electric field strength in...A 4H-SiC power MOSFET with specific on-resistance of 3.4 mΩ·cm^2 and breakdown voltage exceeding 1.5 kV is designed and fabricated.Numerical simulations are carried out to optimize the electric field strength in gate oxide and at the surface of the semiconductor material in the edge termination region.Additional n-type implantation in JFET region is implemented to reduce the specific on-resistance.The typical leakage current is less than 1μA at VDS=1.4 kV.Drain–source current reaches 50 A at VDS=0.75 V and VGS=20 V corresponding to an on-resistance of 15 mΩ.The typical gate threshold voltage is 2.6 V.展开更多
Indacenodithiophene(IDT)derivatives are kinds of the most representative and widely used cores of small molecule acceptors(SMAs)in organic solar cells(OSCs).Here we systematically investigate the influence of end-grou...Indacenodithiophene(IDT)derivatives are kinds of the most representative and widely used cores of small molecule acceptors(SMAs)in organic solar cells(OSCs).Here we systematically investigate the influence of end-group fluo rination density and position on the photovoltaic properties of the IDT-based SMAs IDIC-nF(n=0,2,4).The absorption edge of IDIC-nF red-shifts with theπ-πstacking and crystallinity improvement,and their electronic energy levels downshift with increasing n.Due to the advantages of J_(sc)and FF as well as acceptable V_(oc),the difluorinated IDIC-2 F acceptor based OSCs achieve the highest power conversion efficiency(PCE)of 13%,better than the OSC devices based on IDIC and IDIC-4 F as acceptors.And the photovoltaic performance of the PTQ10:IDIC-2 F OSCs is insensitive to the active layer thickness:PCE still keep high values of 12.00%and 11.46%for the devices with active layer thickness of 80 and 354 nm,respectively.This work verifies that fine and delicate modulation of the SMAs molecular structure could optimize photovoltaic performance of the corresponding OSCs.Meanwhile,the thickness-insensitivity property of the OSCs has potential for large-scale and printable fabrication technology.展开更多
Reconfigurable intelligent surface(RIS)-assisted symbiotic radio is a spectrum-and energy-efficient communication paradigm,in which an RIS performs passive beamforming to enhance active transmission,while using the el...Reconfigurable intelligent surface(RIS)-assisted symbiotic radio is a spectrum-and energy-efficient communication paradigm,in which an RIS performs passive beamforming to enhance active transmission,while using the electromagnetic waves from the active transmission for additional information transfer(i.e.,passive transmission).In this paper,a hybrid RIS-based modulation,termed hybrid phase and code modulation(HPCM),is proposed to improve the reliability of RIS-assisted symbiotic radio.In RIS-HPCM,the RIS simultaneously performs direct sequence spread spectrum and passive beamforming on incident signals.Moreover,both the spreading code and phase offset are exploited to carry the RIS’s own information.A low-complexity detector is designed,in which the receiver first detects the spreading codes and then demodulates the constellation symbols.We analyze the bit error rate(BER)performance of RIS-HPCM over Rician fading channels.BER upper bounds and approximate BER expressions are derived in closed-form for maximum-likelihood and low-complexity detectors,respectively.Simulation results in terms of BER verify the analysis and show the superiority of RIS-HPCM over the existing RIS-based modulation.展开更多
Kiwifruit canker disease seriously affects the yield and quality of"Guichang"kiwifruit in Xiuwen County,Guizhou Province.In order to scientifically,safely,greenly and efficiently prevent and control the dise...Kiwifruit canker disease seriously affects the yield and quality of"Guichang"kiwifruit in Xiuwen County,Guizhou Province.In order to scientifically,safely,greenly and efficiently prevent and control the disease,theory was combined with prevention and control techniques to optimize existing prevention and control techniques,so as to improve the production yield and quality of kiwifruit.Specifically,biocontrol strains targeting local kiwifruit canker disease were screened,and reduced and mixed use of agrochemicals with improved efficiency was studied;and the effects and application techniques of disease resistance inducers and bioorganic fertilizers in inducing systemic disease resistance in kiwifruit trees were explored,and finally,an integrated green prevention and control scheme for kiwifruit canker disease that is suitable for kiwifruit production areas in Guizhou Province and has strong operability was proposed.This study provides technical support for green,efficient,standardized production technical services and sustainable and healthy development of kiwifruit industry.展开更多
Dictyophora rubrovalvata is an edible fungus with rich nutritional value.It contains various nutrients and bioactive components,and has immunomodulation,anti-tumor,anti-oxidation,anti-fatigue,anti-aging,anti-inflammat...Dictyophora rubrovalvata is an edible fungus with rich nutritional value.It contains various nutrients and bioactive components,and has immunomodulation,anti-tumor,anti-oxidation,anti-fatigue,anti-aging,anti-inflammation and alcoholic hepatitis-protection effects.With the continuous expansion of planting area of Dictyophora,the disease problem has become a major problem affecting the development of Dictyophora industry.In this paper,the pathogens,harmful symptoms and causes of main diseases in Dictyophora were summarized,so as to provide reference for comprehensive control of Dictyophora diseases and promote the high-quality development of Dictyophora industry.展开更多
Ni/β-Ga_2 O_3 lateral Schottky barrier diodes(SBDs) were fabricated on a Sn-doped quasi-degenerate n^+-Ga_2 O_3(201)bulk substrate. The resultant diodes with an area of 7.85 ×10^(-5) cm^2 exhibited excellent rec...Ni/β-Ga_2 O_3 lateral Schottky barrier diodes(SBDs) were fabricated on a Sn-doped quasi-degenerate n^+-Ga_2 O_3(201)bulk substrate. The resultant diodes with an area of 7.85 ×10^(-5) cm^2 exhibited excellent rectifying characteristics with an ideality factor of 1.21, a forward current density(J) of 127.4 A/cm2 at 1.4 V, a specific on-state resistance(R_(on,sp)) of1.54 mΩ·cm^2,and an ultra-high on/off ratio of 2.1 ×10^(11) at±1 V. Due to a small depletion region in the highly-doped substrate, a breakdown feature was observed at-23 V, which corresponded to a breakdown field of 2.1 MV/cm and a power figure-of-merit(VB2/R_(on)) of 3.4×10~5 W/cm^2. Forward current-voltage characteristics were described well by the thermionic emission theory while thermionic field emission and trap-assisted tunneling were the dominant transport mechanisms at low and high reverse biases, respectively, which was a result of the contribution of deep-level traps at the metal-semiconductor interface. The presence of interfacial traps also caused the difference in Schottky barrier heights of 1.31 eV and 1.64 eV respectively determined by current-voltage and capacitance-voltage characteristics. With reduced trapping effect and incorporation of drift layers, the β-Ga_2 O_3 SBDs could further provide promising materials for delivering both high current output and high breakdown voltage.展开更多
When zero-valent iron(ZVI)is prepared and applied under neutral conditions,it is easy to form oxides or hydroxides on its surface,which hinders the electron release of ZVI.To this end,a nucleophile was introduced into...When zero-valent iron(ZVI)is prepared and applied under neutral conditions,it is easy to form oxides or hydroxides on its surface,which hinders the electron release of ZVI.To this end,a nucleophile was introduced into the ZVI system to inhibit the precipitation of iron ions,improve the conductivity of the solution,and promote the removal efficiency of electrophilic functional groups in organic compounds.In this study,the addition of nucleophiles such as ethylenediamine,methylamine and dimethylamine to the ZVI/H_(2)O_(2)system resulted in an enhanced removal efficiency of tetracycline(TC)under neutral condition,while electrophiles such as EDTA-2Na and oxalic acid dihydrate impeded the removal of TC.Experimental results demonstrated that the presence of nucleophiles could effectively promote the release of iron ions and increase the proportion of ferrous in both aqueous solution and solid surface of ZVI.Experimental and theoretical calculation results revealed that the electrophilic functional group was eliminated in the TC molecule,and the toxicity of the treated solution was reduced significantly.Overall,this work provides a selection of the conditions and pollutants applicable to ZVI under neutral pH conditions.展开更多
BACKGROUND Persistent suspicion of prostate cancer(PCa)due to a rising prostate-specific antigen(PSA)level after repeated negative biopsies is a serious challenge in clinical practice.AIM To determine the role of Hira...BACKGROUND Persistent suspicion of prostate cancer(PCa)due to a rising prostate-specific antigen(PSA)level after repeated negative biopsies is a serious challenge in clinical practice.AIM To determine the role of Hiraoka’s transurethral detachment of the prostate(TUDP)combined with biopsy of the peripheral zone during the same session in patients with repeated negative biopsies in the diagnosis of PCa.METHODS We retrospectively evaluated the records of 10 patients who were eligible for inclusion in our hospital between December 2012 and August 2017.Patient demographics,a family history of PCa,the number of biopsies,prostate volume,pathological examination,and perioperative PSA level were obtained.RESULTS Two of 10 patients were pathologically diagnosed with PCa after surgery;the Gleason scores were 4+4 and 4+3,respectively.Both patients subsequently underwent laparoscopic radical prostatectomy.The median PSA levels preoperatively,and 3 mo and 1 year postoperatively in the other eight patients who were diagnosed with benign prostate hyperplasia after surgery were 19.10 ng/mL,1.10 ng/mL,and 1.15 ng/mL,respectively.The adjusted P values of the 3-mo and 1-year post-operative PSA level vs pre-operative PSA level were 0.003 and 0.026,respectively.None of the patients had increased PSA levels or PCa detected after a median 35 mo of follow-up.CONCLUSION TUDP combined with peripheral zone biopsy may improve the detection rate of PCa in patients with repeated negative biopsies.The PSA level declined rapidly in patients who had negative pathological examinations after TUDP,which remained stable 1 year after surgery.展开更多
BACKGROUND Timely and accurate evaluation of the patient's pulmonary arterial pressure(PAP)is of great significance for the treatment of congenital heart disease.Currently,there is no non-invasive gold standard me...BACKGROUND Timely and accurate evaluation of the patient's pulmonary arterial pressure(PAP)is of great significance for the treatment of congenital heart disease.Currently,there is no non-invasive gold standard method for evaluating PAP.AIM To assess the prognostic value of lipocalin-2(LCN2)in relation to PAP in patients with congenital heart disease associated with pulmonary artery hypertension.METHODS We conducted a retrospective analysis of 69 pediatric patients diagnosed with ventricular septal defects.The patients’clinical and laboratory data were collected.The serum LCN2 concentrations were compared between the pulmonary arterial hypertension(PAH)group and the nonPAH group.The correlation of LCN2 concentration with PAH classification was evaluated using binary logistic regression analysis.The receiver operating characteristic(ROC)curve was used to evaluate the diagnostic potential of LCN2 for PAH.RESULTS Serum LCN2 concentration significantly correlated with patients’mean PAP(r=0.544,P<0.001),but not correlated with creatinine(P=0.446)or blood urea nitrogen(P=0.747).LCN2 levels were significantly correlated with PAH in both univariate[odds ratio(OR)1.107,95%CI:1.033-1.185,P=0.004)]and multivariate regression analysis(OR 1.150,95%CI:1.027-1.288,P=0.015).ROC curve analysis revealed an area under the curve of 0.783 for LCN2.At the cutoff value of 19.42 ng/mL,the sensitivity and specificity of LCN2 for diagnosing PAH is 90.19%and 55.56%,respectively.LCN2 concentration also significantly correlated with the post-repair mean PAP in patients with congenital heart disease(r=0.532,P=0.009).CONCLUSION LCN2 is emerging as a candidate biomarker for assessing PAP in patients with congenital heart disease.Its high sensitivity in diagnosing PAH makes it a valuable tool in patient management.展开更多
A silicon carbide (SiC) vertical channel junction field effect transistor (VJFET) was fabricated based on in-house SiC epitaxial wafer with trenched and implanted method. Its forward drain current is in excess of 3.12...A silicon carbide (SiC) vertical channel junction field effect transistor (VJFET) was fabricated based on in-house SiC epitaxial wafer with trenched and implanted method. Its forward drain current is in excess of 3.12 A (170 W/cm2) with a current gain of ID/IG = 19746 at gate bias VG = 3 V and drain bias VD = 5.5 V. The SiC VJFET device’s related specific on-resistance 54 mΩ·cm2. The BV gain is 250 V with Vg from -10 V to -4 V and is 350 V with Vg from -4 V to -2 V. Self-aligned floating guard rings provide edge termination that blocks 3180V at a gate bias of ?14 V and a drain-current density of 1.53 mA/cm2.展开更多
Crystal phase engineering on photocatalytic materials is a subfield of photocatalysis with intensive research,which has been proven as a:versatile approach to maneuver their performance for applications in energy-and ...Crystal phase engineering on photocatalytic materials is a subfield of photocatalysis with intensive research,which has been proven as a:versatile approach to maneuver their performance for applications in energy-and environment-related fields.In this article,the state-of-the-art progress on phase-e ngin eered photocatalytic materials is reviewed.Firstly,we discuss the phase engin eeri ng on pristi ne semic on ductor photocatalysts,in which the phase-dependent light absorption,charge transfer and separation,and surface reaction behaviors in photocatalytic processes are summarized,respectively.Based on the elucidated mechanisms,the implementation of phase junctions in photocatalytic reactions is then presented.As a focus,we highlight the rational design of phase junctions toward steering the charge kinetics for enhanced photocatalytic and photoelectrocatalytic performance.Moreover,the crystal phase engineering on semiconductor-based hybrid photocatalysts is also in troduced,which un derli nes the importa nee of choosi ng a suitable phase for semic on ductor comp orients and co-catalysts as well as the synergism of differe nt semico nductor phases for improved photocatalytic performa nee.Fin ally,the challe nges and perspectives in this research field are proposed.In this review,particular emphasis is placed on establishing a linkage between crystal phase and photocatalytic activity to develop a structure-activity guide.Based on the guide,a framework is suggested for future research on the rational phase design of photocatalysts for improved performance in energy and environmental applications.展开更多
Graphene dispersions in low-boiling-point green solvents have wide applications in coatings,conducting inks,batteries,electronics and solar cells.Two three-dimensional(3D)cathode interfacial materials(CIMs)(1,3,5,7,9,...Graphene dispersions in low-boiling-point green solvents have wide applications in coatings,conducting inks,batteries,electronics and solar cells.Two three-dimensional(3D)cathode interfacial materials(CIMs)(1,3,5,7,9,11,13,15-octa-(9-bis(30-(N,N-dimethylamino)propyl)-2,7-fluorene)-vinylpentacyclo-octasiloxane)(POSSFN)and(1,3,5,7-tetra-(9-bis(30-(N,N-dimethylamino)propyl)-2,7-fluorene)-adamantane)(ADMAFN)are excellent surfactants for dispersing graphene in ethanol at the concentration of 0.97–1.18 mg mL−1,in agreement with their calculated large adsorption energies on graphene.The results of electron spin resonance,Raman,scanning Kelvin probe microscopy and X-ray photoelectron spectroscopy measurements indicate that the amino groups could n-dope graphene or form dipole interaction with graphene.The two 3D-surfactant-based graphene composites(POSSFN-G and ADMAFN-G)can work as high-performance CIMs in organic solar cells(OSCs),which improve the power conversion efficiency(PCE)of the OSCs based on PM6:Y6 to 15.9%–16.1%.ADMAFN forms dipole interaction with graphene in ADMAFN-G and the composite CIM delivers high PCE of 16.11%in the OSCs,while POSSFN forms n-doped composition with graphene in POSSFN-G which works well as thicker CIM film in the OSCs.展开更多
文摘Layered transition metal hydroxides show distinct advantages in separately co-catalyzing CO_(2)reduction and H_(2)O oxidation at the electron-accumulating and hole-accumulating sites of wrapped heterojunction photocatalysts,while concurrently preventing side reactions and photocorrosion on the semiconductor surface.Herein,Ni-Co bimetallic hydroxides with varying Ni/Co molar ratios(Ni_(x)Co_(1-x)(OH)_(2),x=1,0.75,0.5,0.25,and 0)were grown in situ on a model 2D/2D S-scheme heterojunction composed of Cu_(2)O nanosheets and Fe_(2)O_(3)nanoplates to form a series of Cu_(2)O/Fe_(2)O_(3)@Ni_(x)Co_(1-x)(OH)_(2)(CF@NiCo)photocatalysts.The combined experimental and theoretical investigation demonstrates that incorporating an appropriate amount of Co into Ni(OH)_(2)not only modulates the energy band structure of Ni_(x)Co_(1-x)(OH)_(2),balances the electron-and hole-trapping abilities of the bifunctional cocatalyst and maximizes the charge separation efficiency of the heterojunction,but also regulates the d-band center of Ni_(x)Co_(1-x)(OH)_(2),reinforcing the adsorption and activation of CO_(2)and H_(2)O on the cocatalyst surface and lowering the rate-limiting barriers in the CO_(2)-to-CO and H_(2)O-to-O_(2)conversion.Benefiting from the Ni-Co synergy,the redox reactions proceed stoichiometrically.The optimized CF@Ni_(0.75)Co_(0.25)achieves CO and O_(2)yields of 552.7 and 313.0μmol gcat^(-1)h^(-1),respectively,11.3/9.9,1.6/1.7,and 4.5/5.9-fold higher than those of CF,CF@Ni,and CF@Co.This study offers valuable insights into the design of bifunctional noble-metal-free cocatalysts for high-performance artificial photosynthesis.
基金Supported by College-level Scientific Research Project of Guizhou Industry Polytechnic College(2023ZK112023ZK10)Scientific and Technological Innovation Team Project of Guizhou Industry Polytechnic College(2023CXTD03).
文摘To further enhance the yield and quality of kiwifruit and promote the sustainable development of the kiwifruit industry,this paper summarized the characteristics,damage sites,and control methods of major kiwifruit diseases and pests.It pointed out the main issues in current kiwifruit pest and disease management and proposed corresponding solutions.The prevention and control of kiwifruit pests should adhere to the principle of"prevention first,integrated management",and standardized planting modes should be implemented.In this process,priority should be given to agricultural,physical,and biological control methods to effectively reduce the use of chemical pesticides.
基金This work was supported by National Natural Science Foundation of China(31271646)Agricultural and Rural Department Foundation of Guangdong Province(2018kczx06)+1 种基金Special fund for scientific innovation strategy-construction of high-level Academy of Agriculture Science(R2019QD-002)Key Areas Research Projects of Guangdong Province(2020B020225004)and(2018B020202004).
文摘Climate conditions is an important factor affected the fragrant rice growth and development.In order to study the effects of different planting seasons on fragrant rice performance in South China,present study was conducted with three planting seasons(early season(April to July),middle season(June to September)and late season(August to November))and three fragrant rice cultivars,‘Basmati-385’,‘Meixiangzhan-2’and‘Xiangyaxiangzhan’.The results showed that the highest grain yield and grain 2-acetyl-1-pyrroline(2-AP,key component of fragrant rice aroma)content were both recorded in late season treatment while the fragrant rice in middle season treatment produced the lowest grain yield,grain filling percentage,1000-grain weight and gain 2-AP content.The highest contents of precursors(proline,pyrroline-5-carboxylic acid and 1-pyrro-line)which related to 2-AP biosynthesis were recorded in late season treatment compared with early season treatment and middle season treatment.The highest activities of enzymes(proline dehydrogenase,pyrroline-5-carboxylic acid synthetase and ornithine transaminase)which involved in 2-AP biosynthesis were also observed in late season treatment.Moreover,the fragrant rice cultivars in late season possessed the lowest chalk rice rate,chalkiness as well as the highest brown rice rate,head rice and protein content.Thus,the optimal season for fragrant rice production in South China is the late season.
基金the financial support from National Natural Science Foundation of China(Nos.11402025,11475019,and 11702123)the National Key Laboratory of Science and Technology on Vacuum Technology&Physics(No.ZWK1608)+1 种基金the Advanced Space Propulsion Laboratory of BICEBeijing Engineering Research Center of Efficient and Green Aerospace Propulsion Technology(No.Lab ASP-2018-03)。
文摘The industrial application of the Kaufman ion thruster in its arc stage is limited owing to the instability of the discharge pulse.Presently,a complete prediction model that can predict the discharge pulse in the high-current stage does not exist.In this study,a complete prediction model for the pulse in the ion thruster is established using the zero-dimensional plasma discharge model and equivalent circuit model.The zero-dimensional plasma discharge model is used to obtain the corresponding plasma parameters by calculating the beam current,discharge current,voltage,and gas flow under actual working conditions.The input parameters of the equivalent circuit model are calculated using empirical formulae to acquire the estimated discharge waveforms.The pulse waveforms obtained using the model are found to be consistent with the experimental results.The model is used to evaluate the process of rapid changes in plasma density.Additionally,this model is employed to predict changes in the pulse waveforms when the volume of the discharge chamber and grid plate transmittance are changed.
基金supported by the National Science and Technology Major Project(No.2017YFB0102302)。
文摘A 4H-SiC power MOSFET with specific on-resistance of 3.4 mΩ·cm^2 and breakdown voltage exceeding 1.5 kV is designed and fabricated.Numerical simulations are carried out to optimize the electric field strength in gate oxide and at the surface of the semiconductor material in the edge termination region.Additional n-type implantation in JFET region is implemented to reduce the specific on-resistance.The typical leakage current is less than 1μA at VDS=1.4 kV.Drain–source current reaches 50 A at VDS=0.75 V and VGS=20 V corresponding to an on-resistance of 15 mΩ.The typical gate threshold voltage is 2.6 V.
基金supported by the Natural Science Foundation of China(Nos.51820105003,51863002 and 51973042)Excellent young scientific and technological talents of Guizhou,China(No.QKHPTRC[2019]5652)。
文摘Indacenodithiophene(IDT)derivatives are kinds of the most representative and widely used cores of small molecule acceptors(SMAs)in organic solar cells(OSCs).Here we systematically investigate the influence of end-group fluo rination density and position on the photovoltaic properties of the IDT-based SMAs IDIC-nF(n=0,2,4).The absorption edge of IDIC-nF red-shifts with theπ-πstacking and crystallinity improvement,and their electronic energy levels downshift with increasing n.Due to the advantages of J_(sc)and FF as well as acceptable V_(oc),the difluorinated IDIC-2 F acceptor based OSCs achieve the highest power conversion efficiency(PCE)of 13%,better than the OSC devices based on IDIC and IDIC-4 F as acceptors.And the photovoltaic performance of the PTQ10:IDIC-2 F OSCs is insensitive to the active layer thickness:PCE still keep high values of 12.00%and 11.46%for the devices with active layer thickness of 80 and 354 nm,respectively.This work verifies that fine and delicate modulation of the SMAs molecular structure could optimize photovoltaic performance of the corresponding OSCs.Meanwhile,the thickness-insensitivity property of the OSCs has potential for large-scale and printable fabrication technology.
基金supported in part by the National Natural Science Foundation of China under Grant 62201228 and Grant 62001190in part by the Science and Technology Major Project of Tibetan Autonomous Region of China under Grant No.XZ202201ZD0006G02.
文摘Reconfigurable intelligent surface(RIS)-assisted symbiotic radio is a spectrum-and energy-efficient communication paradigm,in which an RIS performs passive beamforming to enhance active transmission,while using the electromagnetic waves from the active transmission for additional information transfer(i.e.,passive transmission).In this paper,a hybrid RIS-based modulation,termed hybrid phase and code modulation(HPCM),is proposed to improve the reliability of RIS-assisted symbiotic radio.In RIS-HPCM,the RIS simultaneously performs direct sequence spread spectrum and passive beamforming on incident signals.Moreover,both the spreading code and phase offset are exploited to carry the RIS’s own information.A low-complexity detector is designed,in which the receiver first detects the spreading codes and then demodulates the constellation symbols.We analyze the bit error rate(BER)performance of RIS-HPCM over Rician fading channels.BER upper bounds and approximate BER expressions are derived in closed-form for maximum-likelihood and low-complexity detectors,respectively.Simulation results in terms of BER verify the analysis and show the superiority of RIS-HPCM over the existing RIS-based modulation.
基金Supported by Science and Technology Support Program of Guizhou Province(QKHZC[2020]1Y135)General Higher Education Science and Technology Top-notch Talents Project of Guizhou Province(QJH KY Z[2021]037)+5 种基金Science and Technology Program of Guizhou Province(QKHJZ-ZK[2022]ZD 025)High-level Talent Scientific Research Startup Project of Guizhou Institute of Technology(XJGC20190632)Earth Thesis Project of Guizhou Institute of Technology(KJZX20-005)High-Level Talent Initial Funding of Guizhou Industry Polytechnic College(2023-RC-01)Enterprise Commissioned Project of Guizhou Industrial Polytechnic College(2023-HX-01)Enterprise Commissioned Project of Guizhou Industrial Polytechnic College(2023-HX-02).
文摘Kiwifruit canker disease seriously affects the yield and quality of"Guichang"kiwifruit in Xiuwen County,Guizhou Province.In order to scientifically,safely,greenly and efficiently prevent and control the disease,theory was combined with prevention and control techniques to optimize existing prevention and control techniques,so as to improve the production yield and quality of kiwifruit.Specifically,biocontrol strains targeting local kiwifruit canker disease were screened,and reduced and mixed use of agrochemicals with improved efficiency was studied;and the effects and application techniques of disease resistance inducers and bioorganic fertilizers in inducing systemic disease resistance in kiwifruit trees were explored,and finally,an integrated green prevention and control scheme for kiwifruit canker disease that is suitable for kiwifruit production areas in Guizhou Province and has strong operability was proposed.This study provides technical support for green,efficient,standardized production technical services and sustainable and healthy development of kiwifruit industry.
基金Supported by Guiyang Science and Technology Planning Project (ZKHT[2020]3-13).
文摘Dictyophora rubrovalvata is an edible fungus with rich nutritional value.It contains various nutrients and bioactive components,and has immunomodulation,anti-tumor,anti-oxidation,anti-fatigue,anti-aging,anti-inflammation and alcoholic hepatitis-protection effects.With the continuous expansion of planting area of Dictyophora,the disease problem has become a major problem affecting the development of Dictyophora industry.In this paper,the pathogens,harmful symptoms and causes of main diseases in Dictyophora were summarized,so as to provide reference for comprehensive control of Dictyophora diseases and promote the high-quality development of Dictyophora industry.
基金supported by the National Key R&D Program of China(Grant No.2017YFB0403003)the National Natural Science Foundation of China(Grant Nos.61774081,61322403,and 91850112)+3 种基金the State Key R&D Project of Jiangsu,China(Grant No.BE2018115)Shenzhen Fundamental Research Project,China(Grant Nos.201773239 and 201888588)State Key Laboratory of Wide-Bandgap Semiconductor Power Electric Devices,China(Grant No.2017KF001)the Fundamental Research Funds for the Central Universities,China(Grant Nos.021014380093 and 021014380085)
文摘Ni/β-Ga_2 O_3 lateral Schottky barrier diodes(SBDs) were fabricated on a Sn-doped quasi-degenerate n^+-Ga_2 O_3(201)bulk substrate. The resultant diodes with an area of 7.85 ×10^(-5) cm^2 exhibited excellent rectifying characteristics with an ideality factor of 1.21, a forward current density(J) of 127.4 A/cm2 at 1.4 V, a specific on-state resistance(R_(on,sp)) of1.54 mΩ·cm^2,and an ultra-high on/off ratio of 2.1 ×10^(11) at±1 V. Due to a small depletion region in the highly-doped substrate, a breakdown feature was observed at-23 V, which corresponded to a breakdown field of 2.1 MV/cm and a power figure-of-merit(VB2/R_(on)) of 3.4×10~5 W/cm^2. Forward current-voltage characteristics were described well by the thermionic emission theory while thermionic field emission and trap-assisted tunneling were the dominant transport mechanisms at low and high reverse biases, respectively, which was a result of the contribution of deep-level traps at the metal-semiconductor interface. The presence of interfacial traps also caused the difference in Schottky barrier heights of 1.31 eV and 1.64 eV respectively determined by current-voltage and capacitance-voltage characteristics. With reduced trapping effect and incorporation of drift layers, the β-Ga_2 O_3 SBDs could further provide promising materials for delivering both high current output and high breakdown voltage.
基金financial support from Sichuan Science and Technology Program(No.2023NSFSC0345)the Fundamental Research Funds for the Central Universities(Southwest Minzu University,No.ZYN2022002)+1 种基金the Innovation Scientific Research Program for Graduates of Southwest Minzu University(Southwest Minzu University,No.3300222156)the China Scholarship Council(No.202008510077)。
文摘When zero-valent iron(ZVI)is prepared and applied under neutral conditions,it is easy to form oxides or hydroxides on its surface,which hinders the electron release of ZVI.To this end,a nucleophile was introduced into the ZVI system to inhibit the precipitation of iron ions,improve the conductivity of the solution,and promote the removal efficiency of electrophilic functional groups in organic compounds.In this study,the addition of nucleophiles such as ethylenediamine,methylamine and dimethylamine to the ZVI/H_(2)O_(2)system resulted in an enhanced removal efficiency of tetracycline(TC)under neutral condition,while electrophiles such as EDTA-2Na and oxalic acid dihydrate impeded the removal of TC.Experimental results demonstrated that the presence of nucleophiles could effectively promote the release of iron ions and increase the proportion of ferrous in both aqueous solution and solid surface of ZVI.Experimental and theoretical calculation results revealed that the electrophilic functional group was eliminated in the TC molecule,and the toxicity of the treated solution was reduced significantly.Overall,this work provides a selection of the conditions and pollutants applicable to ZVI under neutral pH conditions.
基金Supported by Shengjing Hospital Science and Technology Program,No.MC05.
文摘BACKGROUND Persistent suspicion of prostate cancer(PCa)due to a rising prostate-specific antigen(PSA)level after repeated negative biopsies is a serious challenge in clinical practice.AIM To determine the role of Hiraoka’s transurethral detachment of the prostate(TUDP)combined with biopsy of the peripheral zone during the same session in patients with repeated negative biopsies in the diagnosis of PCa.METHODS We retrospectively evaluated the records of 10 patients who were eligible for inclusion in our hospital between December 2012 and August 2017.Patient demographics,a family history of PCa,the number of biopsies,prostate volume,pathological examination,and perioperative PSA level were obtained.RESULTS Two of 10 patients were pathologically diagnosed with PCa after surgery;the Gleason scores were 4+4 and 4+3,respectively.Both patients subsequently underwent laparoscopic radical prostatectomy.The median PSA levels preoperatively,and 3 mo and 1 year postoperatively in the other eight patients who were diagnosed with benign prostate hyperplasia after surgery were 19.10 ng/mL,1.10 ng/mL,and 1.15 ng/mL,respectively.The adjusted P values of the 3-mo and 1-year post-operative PSA level vs pre-operative PSA level were 0.003 and 0.026,respectively.None of the patients had increased PSA levels or PCa detected after a median 35 mo of follow-up.CONCLUSION TUDP combined with peripheral zone biopsy may improve the detection rate of PCa in patients with repeated negative biopsies.The PSA level declined rapidly in patients who had negative pathological examinations after TUDP,which remained stable 1 year after surgery.
基金Supported by the Scientific Achievements Transformation Incubation Fund of Beijing Children's Hospital,No.ZHFY3-1-015.
文摘BACKGROUND Timely and accurate evaluation of the patient's pulmonary arterial pressure(PAP)is of great significance for the treatment of congenital heart disease.Currently,there is no non-invasive gold standard method for evaluating PAP.AIM To assess the prognostic value of lipocalin-2(LCN2)in relation to PAP in patients with congenital heart disease associated with pulmonary artery hypertension.METHODS We conducted a retrospective analysis of 69 pediatric patients diagnosed with ventricular septal defects.The patients’clinical and laboratory data were collected.The serum LCN2 concentrations were compared between the pulmonary arterial hypertension(PAH)group and the nonPAH group.The correlation of LCN2 concentration with PAH classification was evaluated using binary logistic regression analysis.The receiver operating characteristic(ROC)curve was used to evaluate the diagnostic potential of LCN2 for PAH.RESULTS Serum LCN2 concentration significantly correlated with patients’mean PAP(r=0.544,P<0.001),but not correlated with creatinine(P=0.446)or blood urea nitrogen(P=0.747).LCN2 levels were significantly correlated with PAH in both univariate[odds ratio(OR)1.107,95%CI:1.033-1.185,P=0.004)]and multivariate regression analysis(OR 1.150,95%CI:1.027-1.288,P=0.015).ROC curve analysis revealed an area under the curve of 0.783 for LCN2.At the cutoff value of 19.42 ng/mL,the sensitivity and specificity of LCN2 for diagnosing PAH is 90.19%and 55.56%,respectively.LCN2 concentration also significantly correlated with the post-repair mean PAP in patients with congenital heart disease(r=0.532,P=0.009).CONCLUSION LCN2 is emerging as a candidate biomarker for assessing PAP in patients with congenital heart disease.Its high sensitivity in diagnosing PAH makes it a valuable tool in patient management.
文摘A silicon carbide (SiC) vertical channel junction field effect transistor (VJFET) was fabricated based on in-house SiC epitaxial wafer with trenched and implanted method. Its forward drain current is in excess of 3.12 A (170 W/cm2) with a current gain of ID/IG = 19746 at gate bias VG = 3 V and drain bias VD = 5.5 V. The SiC VJFET device’s related specific on-resistance 54 mΩ·cm2. The BV gain is 250 V with Vg from -10 V to -4 V and is 350 V with Vg from -4 V to -2 V. Self-aligned floating guard rings provide edge termination that blocks 3180V at a gate bias of ?14 V and a drain-current density of 1.53 mA/cm2.
基金This work was financially supported in part by the National Key R&D Program of China(No.2017YFA0207301)the National Natural Science Foundation of China(Nos.21725102,21471141,21603191,and U1532135)+1 种基金CAS Key Research Program of Frontier Sciences(No.QYZDB-SSW-SLH018)CAS Interdisciplinary Innovation Team,and Innovative Program of Development Foundation of Hefei Center for Physical Science and Technology(No.2016FXCX003).
文摘Crystal phase engineering on photocatalytic materials is a subfield of photocatalysis with intensive research,which has been proven as a:versatile approach to maneuver their performance for applications in energy-and environment-related fields.In this article,the state-of-the-art progress on phase-e ngin eered photocatalytic materials is reviewed.Firstly,we discuss the phase engin eeri ng on pristi ne semic on ductor photocatalysts,in which the phase-dependent light absorption,charge transfer and separation,and surface reaction behaviors in photocatalytic processes are summarized,respectively.Based on the elucidated mechanisms,the implementation of phase junctions in photocatalytic reactions is then presented.As a focus,we highlight the rational design of phase junctions toward steering the charge kinetics for enhanced photocatalytic and photoelectrocatalytic performance.Moreover,the crystal phase engineering on semiconductor-based hybrid photocatalysts is also in troduced,which un derli nes the importa nee of choosi ng a suitable phase for semic on ductor comp orients and co-catalysts as well as the synergism of differe nt semico nductor phases for improved photocatalytic performa nee.Fin ally,the challe nges and perspectives in this research field are proposed.In this review,particular emphasis is placed on establishing a linkage between crystal phase and photocatalytic activity to develop a structure-activity guide.Based on the guide,a framework is suggested for future research on the rational phase design of photocatalysts for improved performance in energy and environmental applications.
基金the National Natural Science Foundation of China(51820105003,51863002 and 51973042)the Excellent Young Scientific and Technological Talents of Guizhou,China(QKHPTRC[2019]5652)。
文摘Graphene dispersions in low-boiling-point green solvents have wide applications in coatings,conducting inks,batteries,electronics and solar cells.Two three-dimensional(3D)cathode interfacial materials(CIMs)(1,3,5,7,9,11,13,15-octa-(9-bis(30-(N,N-dimethylamino)propyl)-2,7-fluorene)-vinylpentacyclo-octasiloxane)(POSSFN)and(1,3,5,7-tetra-(9-bis(30-(N,N-dimethylamino)propyl)-2,7-fluorene)-adamantane)(ADMAFN)are excellent surfactants for dispersing graphene in ethanol at the concentration of 0.97–1.18 mg mL−1,in agreement with their calculated large adsorption energies on graphene.The results of electron spin resonance,Raman,scanning Kelvin probe microscopy and X-ray photoelectron spectroscopy measurements indicate that the amino groups could n-dope graphene or form dipole interaction with graphene.The two 3D-surfactant-based graphene composites(POSSFN-G and ADMAFN-G)can work as high-performance CIMs in organic solar cells(OSCs),which improve the power conversion efficiency(PCE)of the OSCs based on PM6:Y6 to 15.9%–16.1%.ADMAFN forms dipole interaction with graphene in ADMAFN-G and the composite CIM delivers high PCE of 16.11%in the OSCs,while POSSFN forms n-doped composition with graphene in POSSFN-G which works well as thicker CIM film in the OSCs.
