Silicon carbide(SiC) is a promising platform for fabricating high-voltage, high-frequency and high-temperature electronic devices such as metal oxide semiconductor field effect transistors in which many junctions or i...Silicon carbide(SiC) is a promising platform for fabricating high-voltage, high-frequency and high-temperature electronic devices such as metal oxide semiconductor field effect transistors in which many junctions or interfaces are involved. The work function(WF) plays an essential role in these devices. However, studies of the effect of conductive type and polar surfaces on the WF of SiC are limited. Here, we report the measurement of WFs of Si-and C-terminated polar surfaces for both p-type and n-type conductive 4H-SiC single crystals by scanning Kelvin probe microscopy(SKPFM). The results show that p-type SiC exhibits a higher WF than n-type SiC.The WF of a C-terminated polar surface is higher than that of a Si-terminated polar surface, which is further confirmed by first-principles calculations. By revealing this long-standing knowledge gap, our work facilitates the fabrication and development of SiC-based electronic devices, which have tremendous potential applications in electric vehicles, photovoltaics, and so on. This work also shows that SKPFM is a good method for identifying polar surfaces of SiC and other polar materials nondestructively, quickly and conveniently.展开更多
Based on the charge balance principle,an optimal impurity distribution variation of lateral doping termination(OIDVLD)and its ion-injection mask design method are proposed and verified.The comparative simulations and ...Based on the charge balance principle,an optimal impurity distribution variation of lateral doping termination(OIDVLD)and its ion-injection mask design method are proposed and verified.The comparative simulations and experiments show that OID-VLD can achieve better blocking ability and reliability than the traditional VLD(T-VLD).Vertical double diffusion MOSFET(VDMOS)with OID-VLD achieved breakdown voltage(BV)of 1684 V and passed the 168 hours 100℃-110℃-120℃-125℃high-temperature reverse bias(HTRB)test,while VDMOS with T-VLD obtained BV of 1636 V and failed in the 20 hours 120℃HTRB test.展开更多
BACKGROUND Around 1 million cases of medical termination of pregnancy(MTP)take place yearly in the United States of America with around 2 percent of this population developing complications.The cardiovascular(CVD)comp...BACKGROUND Around 1 million cases of medical termination of pregnancy(MTP)take place yearly in the United States of America with around 2 percent of this population developing complications.The cardiovascular(CVD)complications occurring post MTP or after stillbirth is not very well described.AIM To help the reader better understand,prepare,and manage these complications by reviewing various cardiac comorbidities seen after MTP.METHODS We performed a literature search in PubMed,Medline,RCA,and google scholar,using the search terms“abortions”or“medical/legal termination of pregnancy”and“cardiac complications”or“cardiovascular complications”.RESULTS The most common complications described in the literature following MTP were infective endocarditis(IE)(n=16),takotsubo cardiomyopathy(TTC)(n=7),arrhythmias(n=5),and sudden coronary artery dissection(SCAD)(n=4).The most common valve involved in IE was the tricuspid valve in 69%(n=10).The most observed causative organism was group B Streptococcus in 81%(n=12).The most common type of TTC was apical type in 57%(n=4).Out of five patients de veloping arrhythmia,bradycardia was the most common and was seen in 60%(3/5)of the patients.All four cases of SCAD-P type presented as acute coronary syndrome 10-14 d post termination of pregnancy with predominant involvement of the right coronary artery.Mortality was only reported following IE in 6.25%.Clinical recovery was reported consistently after optimal medical management following all these complications.CONCLUSION In conclusion,the occurrence of CVD complications following pregnancy termination is infrequently documented in the existing literature.In this review,the most common CVD complication following MTP was noted to be IE and TTC.展开更多
Scientists have long studied gene transcription to better understand gene regulation and expression in living organisms.Transcription is the process by which DNA is copied into RNA,which then produces proteins that pe...Scientists have long studied gene transcription to better understand gene regulation and expression in living organisms.Transcription is the process by which DNA is copied into RNA,which then produces proteins that perform various functions in the body.Efficient and accurate transcription termination is crucial for controlling gene expression and maintaining genomic integrity.展开更多
Background:Acute suppurative terminal cholangitis(ASTC)is rarer than acute obstructive cholangitis and is not well studied.To explore this subtype of acute cholangitis,we described our clinical experience with ASTC.Me...Background:Acute suppurative terminal cholangitis(ASTC)is rarer than acute obstructive cholangitis and is not well studied.To explore this subtype of acute cholangitis,we described our clinical experience with ASTC.Methods:We performed a retrospective review of patients with ASTC admitted to our center from September 2014 to August 2020.We analyzed their clinical characteristics,including etiology,clinical manifestations,imaging features,treatment and prognosis.Results:A total of 32 ASTC patients were included in the analysis.The majority of the patients had a history of biliary operations,and clinical manifestations were occult and atypical.The positive rate of bacterial culture was 46.9%.All the patients had typical imaging features on computed tomography and magnetic resonance imaging.Treatment with effective antibiotics was provided as soon as diagnosis was established.After treatment,most patients had a good outcome.Elevated levels of total bilirubin,aspartate aminotransferase,procalcitonin and gamma-glutamyltransferase were the characteristics of critically ill patients and were associated with relatively poor prognosis.Conclusions:Our results demonstrated that ASTC should be recognized as a new subtype of acute cholangitis,and that earlier diagnosis and more personalized treatments are needed.展开更多
Machine learning(ML) is well suited for the prediction of high-complexity,high-dimensional problems such as those encountered in terminal ballistics.We evaluate the performance of four popular ML-based regression mode...Machine learning(ML) is well suited for the prediction of high-complexity,high-dimensional problems such as those encountered in terminal ballistics.We evaluate the performance of four popular ML-based regression models,extreme gradient boosting(XGBoost),artificial neural network(ANN),support vector regression(SVR),and Gaussian process regression(GP),on two common terminal ballistics’ problems:(a)predicting the V50ballistic limit of monolithic metallic armour impacted by small and medium calibre projectiles and fragments,and(b) predicting the depth to which a projectile will penetrate a target of semi-infinite thickness.To achieve this we utilise two datasets,each consisting of approximately 1000samples,collated from public release sources.We demonstrate that all four model types provide similarly excellent agreement when interpolating within the training data and diverge when extrapolating outside this range.Although extrapolation is not advisable for ML-based regression models,for applications such as lethality/survivability analysis,such capability is required.To circumvent this,we implement expert knowledge and physics-based models via enforced monotonicity,as a Gaussian prior mean,and through a modified loss function.The physics-informed models demonstrate improved performance over both classical physics-based models and the basic ML regression models,providing an ability to accurately fit experimental data when it is available and then revert to the physics-based model when not.The resulting models demonstrate high levels of predictive accuracy over a very wide range of projectile types,target materials and thicknesses,and impact conditions significantly more diverse than that achievable from any existing analytical approach.Compared with numerical analysis tools such as finite element solvers the ML models run orders of magnitude faster.We provide some general guidelines throughout for the development,application,and reporting of ML models in terminal ballistics problems.展开更多
The low efficiency and high cost of fresh agricultural product terminal distribution directly restrict the operation of the entire supply network.To reduce costs and optimize the distribution network,we construct a mi...The low efficiency and high cost of fresh agricultural product terminal distribution directly restrict the operation of the entire supply network.To reduce costs and optimize the distribution network,we construct a mixed integer programmingmodel that comprehensively considers tominimize fixed,transportation,fresh-keeping,time,carbon emissions,and performance incentive costs.We analyzed the performance of traditional rider distribution and robot distribution modes in detail.In addition,the uncertainty of the actual market demand poses a huge threat to the stability of the terminal distribution network.In order to resist uncertain interference,we further extend the model to a robust counterpart form.The results of the simulation show that the instability of random parameters will lead to an increase in the cost.Compared with the traditional rider distribution mode,the robot distribution mode can save 12.7%on logistics costs,and the distribution efficiency is higher.Our research can provide support for the design of planning schemes for transportation enterprise managers.展开更多
Improving the cooperative scheduling efficiency of equipment is the key for automated container terminals to copewith the development trend of large-scale ships. In order to improve the solution efficiency of the exis...Improving the cooperative scheduling efficiency of equipment is the key for automated container terminals to copewith the development trend of large-scale ships. In order to improve the solution efficiency of the existing spacetimenetwork (STN) model for the cooperative scheduling problem of yard cranes (YCs) and automated guidedvehicles (AGVs) and extend its application scenarios, two improved STN models are proposed. The flow balanceconstraints in the original model are decomposed, and the trajectory constraints of YCs and AGVs are added toacquire the model STN_A. The coupling constraint in STN_A is updated, and buffer constraints are added toSTN_A so that themodel STN_B is built.As the size of the problem increases, the solution speed of CPLEX becomesthe bottleneck. So a heuristic method containing three groups of heuristic rules is designed to obtain a near-optimalsolution quickly. Experimental results showthat the computation time of STN_A is shortened by 49.47% on averageand the gap is reduced by 1.69% on average compared with the original model. The gap between the solution ofthe heuristic rules and the solution of CPLEX is less than 3.50%, and the solution time of the heuristic rules is onaverage 99.85% less than the solution time of CPLEX. Compared with STN_A, the computation time for solvingSTN_B increases by 58.93% on average.展开更多
Background: Perforations of the terminal ileum are a frequent clinical situation and a therapeutic challenge. Surgical treatment is controversial. Several surgical modalities have been proposed and postoperative morbi...Background: Perforations of the terminal ileum are a frequent clinical situation and a therapeutic challenge. Surgical treatment is controversial. Several surgical modalities have been proposed and postoperative morbidity and mortality remain high. The aim of this study was to review our experience in the surgical management of perforations of the terminal ileum. Patients and methods: This is a descriptive cross-sectional study with retrospective data collection from January 1, 2017 to December 31, 2021, in five hospitals in Cameroon. Patients’ demographic, clinical presentation, surgical findings and 30-days postoperative outcomes data were collected. Results: We collected 34 files. The sex ratio was 1.4 and the average age was 20.28 years. The average consultation time was 9.1 days. Abdominal pain was present in all our patients. Peritoneal irritation was present in 46 cases (88.5%). The mean time to treatment after admission was 17.5 hours. The perforation was unique in 40 cases (76.9%) and located between 6 and 10 cm from the ileocecal valve in 29 cases (55.8%). Typhoid was the most suspected etiology intraoperatively in 38 cases (73.1%). A simple suture was performed in 18 patients (34.6%), resection with anastomosis in 11 patients (21.2%) and an ileostomy in 5 patients (9.6%). The average length of hospitalization was 21.74 days. Postoperative morbidity and mortality were 32.7% and 17.3% respectively. Conclusion: Perforations of the terminal ileum are common and affect young people. Surgical procedures are varied. Reducing consultation and care times and respecting treatment principles could improve postoperative morbidity and mortality, which remain high.展开更多
As the number of automated guided vehicles(AGVs)within automated container terminals(ACT)continues to rise,conflicts have becomemore frequent.Addressing point and edge conflicts ofAGVs,amulti-AGVconflict-free path pla...As the number of automated guided vehicles(AGVs)within automated container terminals(ACT)continues to rise,conflicts have becomemore frequent.Addressing point and edge conflicts ofAGVs,amulti-AGVconflict-free path planning model has been formulated to minimize the total path length of AGVs between shore bridges and yards.For larger terminalmaps and complex environments,the grid method is employed to model AGVs’road networks.An improved bounded conflict-based search(IBCBS)algorithmtailored to ACT is proposed,leveraging the binary tree principle to resolve conflicts and employing focal search to expand the search range.Comparative experiments involving 60 AGVs indicate a reduction in computing time by 37.397%to 64.06%while maintaining the over cost within 1.019%.Numerical experiments validate the proposed algorithm’s efficacy in enhancing efficiency and ensuring solution quality.展开更多
BACKGROUND High-grade B-cell lymphoma(HGBL)is an unusual malignancy that includes myelocytomatosis viral oncogene(MYC),B-cell lymphoma-2(BCL-2),and/or BCL-6 rearrangements,termed double-hit or triple-hit lymphomas,and...BACKGROUND High-grade B-cell lymphoma(HGBL)is an unusual malignancy that includes myelocytomatosis viral oncogene(MYC),B-cell lymphoma-2(BCL-2),and/or BCL-6 rearrangements,termed double-hit or triple-hit lymphomas,and HGBL-not otherwise specific(HGBL-NOS),which are morphologically characteristic of HGBL but lack MYC,BCL-2,or BCL-6 rearrangements.HGBL is partially transformed by follicular lymphoma and other indolent lymphoma,with few cases of marginal zone lymphoma(MZL)transformation.HGBL often has a poor prognosis and intensive therapy is currently mainly advocated,but there is no good treatment for these patients who cannot tolerate chemotherapy.CASE SUMMARY We reported a case of MZL transformed into HGBL-NOS with TP53 mutation and terminal deoxynucleotidyl transferase expression.Gene analysis revealed the gene expression profile was identical in the pre-and post-transformed tissues,suggesting that the two diseases are homologous,not secondary tumors.The chemotherapy was ineffective and the side effect was severe,so we tried combination therapy including venetoclax and obinutuzumab.The patient tolerated treatment well,and reached partial response.The patient had recurrence of hepatocellular carcinoma and died of multifunctional organ failure.He survived for 12 months after diagnosis.CONCLUSION Venetoclax combined with obinutuzumab might improve the survival in some HGBL patients,who are unsuitable for chemotherapy.展开更多
GaN-based vertical P-i-N diode with mesa edge terminal structure due to electric field crowding effect, the breakdown voltage of the device is significantly reduced. This work investigates three terminal structures, i...GaN-based vertical P-i-N diode with mesa edge terminal structure due to electric field crowding effect, the breakdown voltage of the device is significantly reduced. This work investigates three terminal structures, including deeply etched, bevel, and stepped-mesas terminal structures, to suppress electric field crowding effects at the device and junction edges. Deeply-etched mesa terminal yields a breakdown voltage of 1205 V, i.e., 89% of the ideal voltage. The bevel-mesa terminal achieves about 89% of the ideal breakdown voltage, while the step-mesa terminal is less effective in mitigating electric field crowding, at about 32% of the ideal voltage. This work can provide an important reference for the design of high-power, high-voltage GaN-based P-i-N power devices, finding a terminal protection structure suitable for GaNPiN diodes to further enhance the breakdown performance of the device and to unleash the full potential of GaN semiconductor materials.展开更多
In this work, the field plate termination is studied for Ga2O3Schottky barrier diodes(SBDs) by simulation. The influence of field plate overlap, dielectric material and thickness on the termination electric field dist...In this work, the field plate termination is studied for Ga2O3Schottky barrier diodes(SBDs) by simulation. The influence of field plate overlap, dielectric material and thickness on the termination electric field distribution are demonstrated.It is found that the optimal thickness increases with reverse bias increasing for all the three dielectrics of SiO2, Al2O3, and HfO2. As the thickness increases, the maximum electric field intensity decreases in SiO2and Al2O3, but increases in HfO2.Furthermore, it is found that SiO2and HfO2are suitable for the 600 V rate Ga2O3SBD, and Al2O3is suitable for both600 V and 1200 V rate Ga2O3SBD. In addition, the comparison of Ga2O3SBDs between the SiC and GaN counterpart reveals that for Ga2O3, the breakdown voltage bottleneck is the dielectric. While, for SiC and GaN, the bottleneck is mainly the semiconductor itself.展开更多
AIM: To assess an early termination of immune toler-ance state of chronic hepatitis B virus infection in Ban-gladesh and its clinical significance. METHODS: From a series of 167 treatment-naive chronic hepatitis B pat...AIM: To assess an early termination of immune toler-ance state of chronic hepatitis B virus infection in Ban-gladesh and its clinical significance. METHODS: From a series of 167 treatment-naive chronic hepatitis B patients aged between 12 to 20 years(mean ± SD; 17.5 ± 2.8 years), percutaneous liver biopsies of 89 patients who were all hepatitis B e antigen negative at presentation were done. Of them, 81 were included in the study. They had persistently normal or raised serum alanine aminotransferase(ALT) values. A precore mutation(PCM) study was accom-plished in 8 patients who were randomly selected. RESULTS: Forty-four(53.7%) patients had significant necroinflammation(HAI-NI > 7), while significant fi-brosis(HAI-F ≥ 3) was seen in 15(18.5%) patients. Serum ALT(cut off 42 U/L) was raised in 29(35.8%) patients, while low HBV DNA load(< 105 copies/mL)was observed in 57(70.4%) patients. PCM was nega-tive in all 8 patients. CONCLUSION: This study indicates that the current concept of age-related immune tolerance state of HBV infection deserves further analyses in different popula-tion groups.展开更多
The planar edge termination techniques of junction termination extension (JTE) and offset field plates and fieldlimiting rings for the 4H-SiC P i-N diode were investigated and optimized by using a two-dimensional de...The planar edge termination techniques of junction termination extension (JTE) and offset field plates and fieldlimiting rings for the 4H-SiC P i-N diode were investigated and optimized by using a two-dimensional device simulator ISE-TCAD10.0. By experimental verification, a good consistency between simulation and experiment can be observed. The results show that the reverse breakdown voltage for the 4H-SiC P-i-N diode with optimized JTE edge termination can accomplish near ideal breakdown voltage and much lower leakage current. The breakdown voltage can be near 1650 V, which achieves more than 90 percent of ideal parallel plane junction breakdown voltage and the leakage current density can be near 3 ×10^-5 A/cm2.展开更多
The point-contact high-purity germanium detector(HPGe)has the advantages of low background,low energy threshold,and high energy resolution and can be applied in the detection of rare-event physics.However,the performa...The point-contact high-purity germanium detector(HPGe)has the advantages of low background,low energy threshold,and high energy resolution and can be applied in the detection of rare-event physics.However,the performance of HPGe must be further improved to achieve superior energy resolution,low noise,and long-term reliability.In this study,we combine computational simulations and experimental comparisons to deeply understand the passivation mechanism of Ge.The surface passivation effect is calculated and inferred from the band structure and density of interface states,and further con-firmed by the minority carrier lifetime.The first-principles method based on the density functional theory was adopted to systematically study the lattice structure,band structure,and density of state(DOS)of four different systems:Ge–H,Ge–Ge-NH 2,Ge-OH,and Ge-SiO_(x).The electronic char-acteristics of the Ge(100)unit cell with different passi-vation groups and Si/O atomic ratios were compared.This shows that H,N,and O atoms can effectively reduce the surface DOS of the Ge atoms.The passivation effect of the SiO_(x) group varied with increasing O atoms and Si/O atomic ratios.Experimentally,SiO and SiO_(2) passivation films were fabricated by electron beam evaporation on a Ge substrate,and the valence state of Si and resistivity was measured to characterize the film.The minority carrier lifetime of Ge-SiO_(2) is 21.3 ls,which is approximately quadruple that of Ge-SiO.The passivation effect and mechanism are discussed in terms of hopping conduction and surface defect density.This study builds a relationship between the passivation effect and different termination groups,and provides technical support for the potential passivation layer,which can be applied in Ge detectors with ultralow energy thresholds and especially in HPGe for rare-event physics detection experiments in future.展开更多
The vertical GaN-on-GaN Schottky barrier diode with boron-implanted termination was fabricated and characterized.Compared with the Schottky barrier diode(SBD)without boron-implanted termination,this SBD effectively im...The vertical GaN-on-GaN Schottky barrier diode with boron-implanted termination was fabricated and characterized.Compared with the Schottky barrier diode(SBD)without boron-implanted termination,this SBD effectively improved the breakdown voltage from 189 V to 585 V and significantly reduced the reverse leakage current by 10^5 times.In addition,a high Ion/Ioff ratio of ~10^8 was achieved by the boron-implanted technology.We used Technology Computer Aided Design(TCAD)to analyze reasons for the improved performance of the SBD with boron-implanted termination.The improved performance of diodes may be attributed to that B+could confine free carriers to suppress electron field crowding at the edge of the diode,which could improve the breakdown voltage and suppress the reverse leakage current.展开更多
Continental reconstructions in Central Asia are represented by orogenesis along some large orogenic belts in the Altaid collage (Fig. 1 ) or Central Asian Orogenic Belt (CAOB), which separate the East European and...Continental reconstructions in Central Asia are represented by orogenesis along some large orogenic belts in the Altaid collage (Fig. 1 ) or Central Asian Orogenic Belt (CAOB), which separate the East European and Siberian cratons to the north from the Tarim and North China cratons to the south ($eng0r et al,, 1993; Jahn et al., 2004; Windley et al., 2007; Qu et al., 2008; Xiao et al., 2010; Xiao and Santosh, 2014). The Altaid Collage was characterized by complex long tectonic and structural evolution from at least ca. 1.0 Ga to late Paleozoic-early Mesozoic with considerable continental growth (Khain et al., 2002; Jahn et al., 2004; Xiao et al., 2009, 2014; KrOner et al., 2014), followed by Cenozoic intracontinental evolution related to far-field effect of the collision of the In- dian Plate to the Eurasian Accompanying with these complex world-class ore deposits developed 2001; Goldfarb et al., 2003, 2014). Plate (Cunningham, 2005). geodynamic evolutions, many (Qin, 2000; Yakubchuk et al,2001; Goldfarb et al., 2003, 2014).展开更多
基金financially supported by the Beijing Municipal Science and Technology Project (Grant No. Z231100006023015)the Major Scientific and Technological Research and Development of Shunyi District of Beijingthe Chinese Academy of Sciences。
文摘Silicon carbide(SiC) is a promising platform for fabricating high-voltage, high-frequency and high-temperature electronic devices such as metal oxide semiconductor field effect transistors in which many junctions or interfaces are involved. The work function(WF) plays an essential role in these devices. However, studies of the effect of conductive type and polar surfaces on the WF of SiC are limited. Here, we report the measurement of WFs of Si-and C-terminated polar surfaces for both p-type and n-type conductive 4H-SiC single crystals by scanning Kelvin probe microscopy(SKPFM). The results show that p-type SiC exhibits a higher WF than n-type SiC.The WF of a C-terminated polar surface is higher than that of a Si-terminated polar surface, which is further confirmed by first-principles calculations. By revealing this long-standing knowledge gap, our work facilitates the fabrication and development of SiC-based electronic devices, which have tremendous potential applications in electric vehicles, photovoltaics, and so on. This work also shows that SKPFM is a good method for identifying polar surfaces of SiC and other polar materials nondestructively, quickly and conveniently.
基金Project supported by the Key Research and Development Program of Jiangsu Province,China(Grant No.BE2020010)the Natural Science Foundation of Guangdong Province,China(Grant No.2023A1515012652)。
文摘Based on the charge balance principle,an optimal impurity distribution variation of lateral doping termination(OIDVLD)and its ion-injection mask design method are proposed and verified.The comparative simulations and experiments show that OID-VLD can achieve better blocking ability and reliability than the traditional VLD(T-VLD).Vertical double diffusion MOSFET(VDMOS)with OID-VLD achieved breakdown voltage(BV)of 1684 V and passed the 168 hours 100℃-110℃-120℃-125℃high-temperature reverse bias(HTRB)test,while VDMOS with T-VLD obtained BV of 1636 V and failed in the 20 hours 120℃HTRB test.
文摘BACKGROUND Around 1 million cases of medical termination of pregnancy(MTP)take place yearly in the United States of America with around 2 percent of this population developing complications.The cardiovascular(CVD)complications occurring post MTP or after stillbirth is not very well described.AIM To help the reader better understand,prepare,and manage these complications by reviewing various cardiac comorbidities seen after MTP.METHODS We performed a literature search in PubMed,Medline,RCA,and google scholar,using the search terms“abortions”or“medical/legal termination of pregnancy”and“cardiac complications”or“cardiovascular complications”.RESULTS The most common complications described in the literature following MTP were infective endocarditis(IE)(n=16),takotsubo cardiomyopathy(TTC)(n=7),arrhythmias(n=5),and sudden coronary artery dissection(SCAD)(n=4).The most common valve involved in IE was the tricuspid valve in 69%(n=10).The most observed causative organism was group B Streptococcus in 81%(n=12).The most common type of TTC was apical type in 57%(n=4).Out of five patients de veloping arrhythmia,bradycardia was the most common and was seen in 60%(3/5)of the patients.All four cases of SCAD-P type presented as acute coronary syndrome 10-14 d post termination of pregnancy with predominant involvement of the right coronary artery.Mortality was only reported following IE in 6.25%.Clinical recovery was reported consistently after optimal medical management following all these complications.CONCLUSION In conclusion,the occurrence of CVD complications following pregnancy termination is infrequently documented in the existing literature.In this review,the most common CVD complication following MTP was noted to be IE and TTC.
文摘Scientists have long studied gene transcription to better understand gene regulation and expression in living organisms.Transcription is the process by which DNA is copied into RNA,which then produces proteins that perform various functions in the body.Efficient and accurate transcription termination is crucial for controlling gene expression and maintaining genomic integrity.
基金This study was supported by a grant from the National Natural Science Foundation of China(81870457).
文摘Background:Acute suppurative terminal cholangitis(ASTC)is rarer than acute obstructive cholangitis and is not well studied.To explore this subtype of acute cholangitis,we described our clinical experience with ASTC.Methods:We performed a retrospective review of patients with ASTC admitted to our center from September 2014 to August 2020.We analyzed their clinical characteristics,including etiology,clinical manifestations,imaging features,treatment and prognosis.Results:A total of 32 ASTC patients were included in the analysis.The majority of the patients had a history of biliary operations,and clinical manifestations were occult and atypical.The positive rate of bacterial culture was 46.9%.All the patients had typical imaging features on computed tomography and magnetic resonance imaging.Treatment with effective antibiotics was provided as soon as diagnosis was established.After treatment,most patients had a good outcome.Elevated levels of total bilirubin,aspartate aminotransferase,procalcitonin and gamma-glutamyltransferase were the characteristics of critically ill patients and were associated with relatively poor prognosis.Conclusions:Our results demonstrated that ASTC should be recognized as a new subtype of acute cholangitis,and that earlier diagnosis and more personalized treatments are needed.
文摘Machine learning(ML) is well suited for the prediction of high-complexity,high-dimensional problems such as those encountered in terminal ballistics.We evaluate the performance of four popular ML-based regression models,extreme gradient boosting(XGBoost),artificial neural network(ANN),support vector regression(SVR),and Gaussian process regression(GP),on two common terminal ballistics’ problems:(a)predicting the V50ballistic limit of monolithic metallic armour impacted by small and medium calibre projectiles and fragments,and(b) predicting the depth to which a projectile will penetrate a target of semi-infinite thickness.To achieve this we utilise two datasets,each consisting of approximately 1000samples,collated from public release sources.We demonstrate that all four model types provide similarly excellent agreement when interpolating within the training data and diverge when extrapolating outside this range.Although extrapolation is not advisable for ML-based regression models,for applications such as lethality/survivability analysis,such capability is required.To circumvent this,we implement expert knowledge and physics-based models via enforced monotonicity,as a Gaussian prior mean,and through a modified loss function.The physics-informed models demonstrate improved performance over both classical physics-based models and the basic ML regression models,providing an ability to accurately fit experimental data when it is available and then revert to the physics-based model when not.The resulting models demonstrate high levels of predictive accuracy over a very wide range of projectile types,target materials and thicknesses,and impact conditions significantly more diverse than that achievable from any existing analytical approach.Compared with numerical analysis tools such as finite element solvers the ML models run orders of magnitude faster.We provide some general guidelines throughout for the development,application,and reporting of ML models in terminal ballistics problems.
文摘The low efficiency and high cost of fresh agricultural product terminal distribution directly restrict the operation of the entire supply network.To reduce costs and optimize the distribution network,we construct a mixed integer programmingmodel that comprehensively considers tominimize fixed,transportation,fresh-keeping,time,carbon emissions,and performance incentive costs.We analyzed the performance of traditional rider distribution and robot distribution modes in detail.In addition,the uncertainty of the actual market demand poses a huge threat to the stability of the terminal distribution network.In order to resist uncertain interference,we further extend the model to a robust counterpart form.The results of the simulation show that the instability of random parameters will lead to an increase in the cost.Compared with the traditional rider distribution mode,the robot distribution mode can save 12.7%on logistics costs,and the distribution efficiency is higher.Our research can provide support for the design of planning schemes for transportation enterprise managers.
基金National Natural Science Foundation of China(62073212).
文摘Improving the cooperative scheduling efficiency of equipment is the key for automated container terminals to copewith the development trend of large-scale ships. In order to improve the solution efficiency of the existing spacetimenetwork (STN) model for the cooperative scheduling problem of yard cranes (YCs) and automated guidedvehicles (AGVs) and extend its application scenarios, two improved STN models are proposed. The flow balanceconstraints in the original model are decomposed, and the trajectory constraints of YCs and AGVs are added toacquire the model STN_A. The coupling constraint in STN_A is updated, and buffer constraints are added toSTN_A so that themodel STN_B is built.As the size of the problem increases, the solution speed of CPLEX becomesthe bottleneck. So a heuristic method containing three groups of heuristic rules is designed to obtain a near-optimalsolution quickly. Experimental results showthat the computation time of STN_A is shortened by 49.47% on averageand the gap is reduced by 1.69% on average compared with the original model. The gap between the solution ofthe heuristic rules and the solution of CPLEX is less than 3.50%, and the solution time of the heuristic rules is onaverage 99.85% less than the solution time of CPLEX. Compared with STN_A, the computation time for solvingSTN_B increases by 58.93% on average.
文摘Background: Perforations of the terminal ileum are a frequent clinical situation and a therapeutic challenge. Surgical treatment is controversial. Several surgical modalities have been proposed and postoperative morbidity and mortality remain high. The aim of this study was to review our experience in the surgical management of perforations of the terminal ileum. Patients and methods: This is a descriptive cross-sectional study with retrospective data collection from January 1, 2017 to December 31, 2021, in five hospitals in Cameroon. Patients’ demographic, clinical presentation, surgical findings and 30-days postoperative outcomes data were collected. Results: We collected 34 files. The sex ratio was 1.4 and the average age was 20.28 years. The average consultation time was 9.1 days. Abdominal pain was present in all our patients. Peritoneal irritation was present in 46 cases (88.5%). The mean time to treatment after admission was 17.5 hours. The perforation was unique in 40 cases (76.9%) and located between 6 and 10 cm from the ileocecal valve in 29 cases (55.8%). Typhoid was the most suspected etiology intraoperatively in 38 cases (73.1%). A simple suture was performed in 18 patients (34.6%), resection with anastomosis in 11 patients (21.2%) and an ileostomy in 5 patients (9.6%). The average length of hospitalization was 21.74 days. Postoperative morbidity and mortality were 32.7% and 17.3% respectively. Conclusion: Perforations of the terminal ileum are common and affect young people. Surgical procedures are varied. Reducing consultation and care times and respecting treatment principles could improve postoperative morbidity and mortality, which remain high.
基金supported by National Natural Science Foundation of China(No.62073212)Shanghai Science and Technology Commission(No.23ZR1426600).
文摘As the number of automated guided vehicles(AGVs)within automated container terminals(ACT)continues to rise,conflicts have becomemore frequent.Addressing point and edge conflicts ofAGVs,amulti-AGVconflict-free path planning model has been formulated to minimize the total path length of AGVs between shore bridges and yards.For larger terminalmaps and complex environments,the grid method is employed to model AGVs’road networks.An improved bounded conflict-based search(IBCBS)algorithmtailored to ACT is proposed,leveraging the binary tree principle to resolve conflicts and employing focal search to expand the search range.Comparative experiments involving 60 AGVs indicate a reduction in computing time by 37.397%to 64.06%while maintaining the over cost within 1.019%.Numerical experiments validate the proposed algorithm’s efficacy in enhancing efficiency and ensuring solution quality.
基金Supported by The Lishui Science and Technology Planing Projects,No.2020SJZC048.
文摘BACKGROUND High-grade B-cell lymphoma(HGBL)is an unusual malignancy that includes myelocytomatosis viral oncogene(MYC),B-cell lymphoma-2(BCL-2),and/or BCL-6 rearrangements,termed double-hit or triple-hit lymphomas,and HGBL-not otherwise specific(HGBL-NOS),which are morphologically characteristic of HGBL but lack MYC,BCL-2,or BCL-6 rearrangements.HGBL is partially transformed by follicular lymphoma and other indolent lymphoma,with few cases of marginal zone lymphoma(MZL)transformation.HGBL often has a poor prognosis and intensive therapy is currently mainly advocated,but there is no good treatment for these patients who cannot tolerate chemotherapy.CASE SUMMARY We reported a case of MZL transformed into HGBL-NOS with TP53 mutation and terminal deoxynucleotidyl transferase expression.Gene analysis revealed the gene expression profile was identical in the pre-and post-transformed tissues,suggesting that the two diseases are homologous,not secondary tumors.The chemotherapy was ineffective and the side effect was severe,so we tried combination therapy including venetoclax and obinutuzumab.The patient tolerated treatment well,and reached partial response.The patient had recurrence of hepatocellular carcinoma and died of multifunctional organ failure.He survived for 12 months after diagnosis.CONCLUSION Venetoclax combined with obinutuzumab might improve the survival in some HGBL patients,who are unsuitable for chemotherapy.
文摘GaN-based vertical P-i-N diode with mesa edge terminal structure due to electric field crowding effect, the breakdown voltage of the device is significantly reduced. This work investigates three terminal structures, including deeply etched, bevel, and stepped-mesas terminal structures, to suppress electric field crowding effects at the device and junction edges. Deeply-etched mesa terminal yields a breakdown voltage of 1205 V, i.e., 89% of the ideal voltage. The bevel-mesa terminal achieves about 89% of the ideal breakdown voltage, while the step-mesa terminal is less effective in mitigating electric field crowding, at about 32% of the ideal voltage. This work can provide an important reference for the design of high-power, high-voltage GaN-based P-i-N power devices, finding a terminal protection structure suitable for GaNPiN diodes to further enhance the breakdown performance of the device and to unleash the full potential of GaN semiconductor materials.
基金Project supported by the Research Fund of Low Cost Fabrication of GaN Power Devices and System Integration,China(Grant No.JCYJ20160226192639004)the Research Fund of AlGaN HEMT MEMS Sensor for Work in Extreme Environment,China(Grant No.JCYJ20170412153356899)the Research Fund of Reliability Mechanism and Circuit Simulation of GaN HEMT,China(Grant No.2017A050506002)
文摘In this work, the field plate termination is studied for Ga2O3Schottky barrier diodes(SBDs) by simulation. The influence of field plate overlap, dielectric material and thickness on the termination electric field distribution are demonstrated.It is found that the optimal thickness increases with reverse bias increasing for all the three dielectrics of SiO2, Al2O3, and HfO2. As the thickness increases, the maximum electric field intensity decreases in SiO2and Al2O3, but increases in HfO2.Furthermore, it is found that SiO2and HfO2are suitable for the 600 V rate Ga2O3SBD, and Al2O3is suitable for both600 V and 1200 V rate Ga2O3SBD. In addition, the comparison of Ga2O3SBDs between the SiC and GaN counterpart reveals that for Ga2O3, the breakdown voltage bottleneck is the dielectric. While, for SiC and GaN, the bottleneck is mainly the semiconductor itself.
文摘AIM: To assess an early termination of immune toler-ance state of chronic hepatitis B virus infection in Ban-gladesh and its clinical significance. METHODS: From a series of 167 treatment-naive chronic hepatitis B patients aged between 12 to 20 years(mean ± SD; 17.5 ± 2.8 years), percutaneous liver biopsies of 89 patients who were all hepatitis B e antigen negative at presentation were done. Of them, 81 were included in the study. They had persistently normal or raised serum alanine aminotransferase(ALT) values. A precore mutation(PCM) study was accom-plished in 8 patients who were randomly selected. RESULTS: Forty-four(53.7%) patients had significant necroinflammation(HAI-NI > 7), while significant fi-brosis(HAI-F ≥ 3) was seen in 15(18.5%) patients. Serum ALT(cut off 42 U/L) was raised in 29(35.8%) patients, while low HBV DNA load(< 105 copies/mL)was observed in 57(70.4%) patients. PCM was nega-tive in all 8 patients. CONCLUSION: This study indicates that the current concept of age-related immune tolerance state of HBV infection deserves further analyses in different popula-tion groups.
基金Project supported by the Science and Technology Foundation of Hunan Province of China (Grant No. 2008FJ3102)
文摘The planar edge termination techniques of junction termination extension (JTE) and offset field plates and fieldlimiting rings for the 4H-SiC P i-N diode were investigated and optimized by using a two-dimensional device simulator ISE-TCAD10.0. By experimental verification, a good consistency between simulation and experiment can be observed. The results show that the reverse breakdown voltage for the 4H-SiC P-i-N diode with optimized JTE edge termination can accomplish near ideal breakdown voltage and much lower leakage current. The breakdown voltage can be near 1650 V, which achieves more than 90 percent of ideal parallel plane junction breakdown voltage and the leakage current density can be near 3 ×10^-5 A/cm2.
基金supported by the National Natural Science Foundation of China Youth Fund(No.12005017)。
文摘The point-contact high-purity germanium detector(HPGe)has the advantages of low background,low energy threshold,and high energy resolution and can be applied in the detection of rare-event physics.However,the performance of HPGe must be further improved to achieve superior energy resolution,low noise,and long-term reliability.In this study,we combine computational simulations and experimental comparisons to deeply understand the passivation mechanism of Ge.The surface passivation effect is calculated and inferred from the band structure and density of interface states,and further con-firmed by the minority carrier lifetime.The first-principles method based on the density functional theory was adopted to systematically study the lattice structure,band structure,and density of state(DOS)of four different systems:Ge–H,Ge–Ge-NH 2,Ge-OH,and Ge-SiO_(x).The electronic char-acteristics of the Ge(100)unit cell with different passi-vation groups and Si/O atomic ratios were compared.This shows that H,N,and O atoms can effectively reduce the surface DOS of the Ge atoms.The passivation effect of the SiO_(x) group varied with increasing O atoms and Si/O atomic ratios.Experimentally,SiO and SiO_(2) passivation films were fabricated by electron beam evaporation on a Ge substrate,and the valence state of Si and resistivity was measured to characterize the film.The minority carrier lifetime of Ge-SiO_(2) is 21.3 ls,which is approximately quadruple that of Ge-SiO.The passivation effect and mechanism are discussed in terms of hopping conduction and surface defect density.This study builds a relationship between the passivation effect and different termination groups,and provides technical support for the potential passivation layer,which can be applied in Ge detectors with ultralow energy thresholds and especially in HPGe for rare-event physics detection experiments in future.
基金Project supported by the National Key R&D Program of China(Grant No.2017YFB0404100)Science and Technology Planning Project of Guangdong Province,China(Grant No.2017B010112001)。
文摘The vertical GaN-on-GaN Schottky barrier diode with boron-implanted termination was fabricated and characterized.Compared with the Schottky barrier diode(SBD)without boron-implanted termination,this SBD effectively improved the breakdown voltage from 189 V to 585 V and significantly reduced the reverse leakage current by 10^5 times.In addition,a high Ion/Ioff ratio of ~10^8 was achieved by the boron-implanted technology.We used Technology Computer Aided Design(TCAD)to analyze reasons for the improved performance of the SBD with boron-implanted termination.The improved performance of diodes may be attributed to that B+could confine free carriers to suppress electron field crowding at the edge of the diode,which could improve the breakdown voltage and suppress the reverse leakage current.
基金financially supported by the Natural National Science Foundation of China(Grant Nos.41230207,41202150, 41472192,41390441 and 41190075)
文摘Continental reconstructions in Central Asia are represented by orogenesis along some large orogenic belts in the Altaid collage (Fig. 1 ) or Central Asian Orogenic Belt (CAOB), which separate the East European and Siberian cratons to the north from the Tarim and North China cratons to the south ($eng0r et al,, 1993; Jahn et al., 2004; Windley et al., 2007; Qu et al., 2008; Xiao et al., 2010; Xiao and Santosh, 2014). The Altaid Collage was characterized by complex long tectonic and structural evolution from at least ca. 1.0 Ga to late Paleozoic-early Mesozoic with considerable continental growth (Khain et al., 2002; Jahn et al., 2004; Xiao et al., 2009, 2014; KrOner et al., 2014), followed by Cenozoic intracontinental evolution related to far-field effect of the collision of the In- dian Plate to the Eurasian Accompanying with these complex world-class ore deposits developed 2001; Goldfarb et al., 2003, 2014). Plate (Cunningham, 2005). geodynamic evolutions, many (Qin, 2000; Yakubchuk et al,2001; Goldfarb et al., 2003, 2014).