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Earth-abundant photovoltaic semiconductor NaSbS2 in the rocksalt-derived structure:A first-principles study

Progress in Natural Science:Materials International 2019年第3期29卷 322-328页

作者： Xian Zhang Menglin Huang Peng Xu chen-min dai Zenghua Cai Dan Han Shiyou chen Key Laboratory of Polar Materials and Devices (MOE) and Department of Optoelectronics East China Normal University Department of Physics China Three Gorges University Collaborative Innovation Center of Extreme Optics Shanxi University

NaSbS2was recently proposed as a novel photovoltaic semiconductor with earth-abundant component elements,but its fundamental material properties have not been well *** systematical first-principles calculations for its electronic,optical and defect properties were carried out in the present study,and the results show that:i)NaSbS2in the rocksalt-derived structure has a quasi-direct band gap and thus may have long minority carrier lifetime;ii) its absorption coefficients are as high as 10～4～10～5 cm-1for the visible light and almost isotropic despite that the structure is distorted relative to the high-symmetry rocksalt structure;iii) the effective masses of the electron and hole carriers are anisotropic with much larger values along the z direction than in the x-y plane,and hence the orientational control of thin films should be important for enhancing the photovoltaic performance;iv) the valence and conduction band edges of NaSbS2are close to those of CuGaSe2) so the n-CdS/pCuGaSe2device structure can be inherited to form the n-CdS/p-NaSbS2solar cells;v) the acceptor defects (NaSbantisites and Na vacancies) have very high concentration,making the synthesized NaSbS2always be p-type;vi)the S-rich condition can suppress the formation of deep-level donor defects (S vacancies and SbNaantisites) and therefore should be adopted for fabricating high-efficiency NaSbS2solar cells.

关键词： NaSbS2 Photovoltaic semiconductor Optical absorption coefficients Defects First-principles calculation

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Used car price prediction based on XGBoost and retention rate

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The Journal of China Universities of Posts and Telecommunications 2024年第3期31卷 72-79页

作者： Shen Yutian chen Jian dai min Zhang Sirui Xu Jing Wang Qing College of Mechanical Engineering Yangzhou UniversityYangzhou 225127China College of Economics and Management Southeast University Chengxian CollegeNanjing 210088China Shandong Shuncheng Automobile Trade Co. LtdJinan 250000China

In order to improve the accuracy of used car price prediction,a machine learning prediction model based on the retention rate is proposed in this ***,a random forest algorithm is used to filter the variables in the *** main characteristic variables that affect used car prices,such as new car price,service time,mileage and so on,are filtered ***,the linear regression classification method is introduced to classify the test data into high and low retention rate *** that,the extreme gradient boosting(XGBoost)regression model is built for the two datasets *** prediction results show that the comprehensive evaluation index of the proposed model is 0.548,which is significantly improved compared to 0.488 of the original XGBoost ***,compared with other representative machine learning algorithms,this model shows certain advantages in terms of mean absolute percentage error(MAPE),5%accuracy rate and comprehensive evaluation *** a result,the retention rate-based machine learning model established in this paper has significant advantages in terms of the accuracy of used car price prediction.

关键词： random forest data dimensionality reduction extreme gradient boosting(XGBoost) retention rate price prediction

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Near-field wideband beam training for ELAA with uniform circular array

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Science China(Information Sciences) 2024年第6期67卷 370-383页

作者： Yuhao chen Linglong dai Department of Electronic Engineering Tsinghua UniversityBeijing National Research Center for Information Science and Technology (BNRist)

Extremely large-scale antenna array(ELAA) at millimeter wave(mmWave) and Terahertz(THz)band has been considered a key technology for combating high attenuation in high-frequency bands in future6G communications. Uniform circular arrays(UCAs) have attracted much attention because of their ability to provide flat beamforming gain at all angles. To realize efficient beamforming, beam training is widely used to acquire channel state information. However, with a large antenna number, the beam training overhead in ELAA systems becomes overwhelming. Moreover, with a large bandwidth, the beam defocus effect severely degrades beam training accuracy. To address these issues, this paper proposes a frequency-dependent focusing(FDF)-based beam training scheme to realize effective beam training in near-field wideband ELAA systems with UCA. Specifically, we first analyze the FDF property of UCA, where signals at different subcarriers can simultaneously focus on different distances. Then, by exploiting the FDF property to search different distances using different subcarriers simultaneously, we design a hierarchical codebook and propose an FDFbased beam training scheme. To reveal the effectiveness of the proposed scheme, we compare its necessary beam training overhead with that of existing schemes. Finally, the simulation results demonstrate that the proposed scheme can achieve accurate beam training in near-field wideband UCA systems with a low beam training overhead.

关键词： extremely large-scale antenna array (ELAA) uniform circular array (UCA) near-field wideband beam training

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Characterization of a New HIV-1 Circulating Recombinant Form CRF142_BC—Yunnan,China,2015 and 2021

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China CDC weekly 2024年第42期6卷 1080-1085页

作者： min chen Huichao chen Shouxiong Lei Jie dai Yanling Ma Manhong Jia Yunnan Provincial Key Laboratory of Public Health and Biosafety&Health Laboratory Center Yunnan Center for Disease Control and PreventionKunming CityYunnan ProvinceChina Institute for AIDS/STD Control and Prevention Yunnan Center for Disease Control and PreventionKunming CityYunnan ProvinceChina Division for AIDS/STD Control and Prevention Zhaotong Center for Disease Control and PreventionZhaotong CityYunnan ProvinceChina Yunnan Provincial Key Laboratory of Public Health and Biosafety&Institute for AIDS/STD Control and Prevention Yunnan Center for Disease Control and PreventionKunming CityYunnan ProvinceChina

What is already known about this topic?Recombinant strains dominate the human immunodeficiency virus 1(HIV-1)epidemic in *** Province was the first region in China to report HIV-1 infections in *** long-term HIV-1 epidemic led to the generation of various recombinant *** the 47 circulating recombinant forms(CRFs)reported in China,more than 20 were first identified in Yunnan *** is added by this report?This study reported a previously unrecognized HIV-1 CRF(CRF142_BC)characterized by the insertion of four short subtype B fragments into the subtype C ***142_BC was estimated to have emerged in the mid-1990s,close to the time of the emergence of most known CRF_BCs in *** are the implications for public health practice?The discovery of new CRFs will provide a basis for HIV-1 molecular tracing and intervention *** addition,HIV-1 recombination can alter viral biological *** study of HIV-1 gene variants needs to be intensified.

关键词： properties. China. intensified

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Metagenomics reveals the microbial community and functional metabolism variation in the partial nitritation-anammox process:From collapse to recovery

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Journal of Environmental Sciences 2024年第1期135卷 210-221页

作者： Hong Wang Hui Gong Xiaohu dai min Yang State Key Laboratory of Pollution Control and Resource Reuse College of Environmental Science and EngineeringTongji UniversityShanghai 200092China BIOMATH Department of Data Analysis and Mathematical ModellingGhent UniversityGhent 9000Belgium

Mainstream partial nitritation-anammox(PNA)process easily suffers from performance instability and even reactor collapse in ***,it is of great significance to unveil the characteristic of performance recovery,understand the intrinsic mechanism and then propose operational *** this study,we combined long-term reactor operation,batch tests,and metagenomics to reveal the succession of microbial community and functional metabolism variation from system collapse to *** aeration control(0.10-0.25mg O_(2)/L)was critical for performance *** was also found that Candidatus Brocadia became the dominant flora and its abundance increased from 3.5%to 11.0%.Significant enhancements in carbon metabolism and phospholipid biosynthesis were observed during system recovery,and the genes abundance related to signal transduction was dramatically *** up-regulation of sdh and suc genes showed the processes of succinate dehydrogenation and succinyl-CoA synthesis might stimulate the production of amino acids and the synthesis of proteins,thereby possibly improving the activity and abundance of AnAOB,which was conducive to the performance ***,the increase in abundance of hzs and hdh genes suggested the enhancement of the anammox *** in the abundance of key genes involved in nitrogen metabolism indicated that nitrogen removal pathway was more diverse after system *** achievement of performance recovery was driven by anammox,nitrification and denitrification coupled with dissimilatory nitrate reduction to *** results provide deeper insights into the recovery mechanism of PNA system and also provide a potential regulation strategy for the stable operation of the mainstream PNA process.

关键词： Partial nitritation-anammox Metagenomics Microbial community Functional metabolism Recovery

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Stereoselective synthesis of substituted 1,3-dienes from propargylic esters: electrophilic-metal or redox catalysis?

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Science China Chemistry 2024年第5期67卷 1384-1396页

作者： Mengfu dai Liangliang Song Liang-An chen Jiangsu Collaborative Innovation Center of Biomedical Functional Materials Jiangsu Key Laboratory of New Power BatteriesSchool of Chemistry and Materials ScienceNanjing Normal UniversityNanjing 210023China Jiangsu Co-Innovation Center of Efficient Processing and Utilization of Forest Resources International Innovation Center for Forest Chemicals and MaterialsCollege of Chemical EngineeringNanjing Forestry UniversityNanjing 210037China

1,3-Diene architectures are not only widely present in natural products, pharmaceuticals, and functional organic materials but also serve as versatile building blocks to furnish important functionalized molecules in synthetic chemistry due to conjugated repeating C=C units. Accordingly, various strategies to access substituted 1,3-dienes in a stereoselective manner have been developed. However, chemo-, regio-and stereoselective synthesis of highly substituted 1,3-dienes still remains elusive and challenging. Readily available propargylic esters have emerged as an appealing class of synthetic intermediates for accessing functionalized 1,3-dienes, especially challenging tri-or tetrasubstituted variants, via transition-metal catalysis, including electrophilic metal and redox neutral catalysis. This review, for the first time, systematically highlights recent advances in transitionmetal catalyzed synthesis of substituted 1,3-dienes from propargylic esters, discusses the mechanisms and synthetic utilities, and gives the remaining challenges and potential opportunities in this field.

关键词： 1 3-diene propargylic ester Lewis acid redox catalysis transition metal

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Perioperative and long-term results of ultrasonography-guided single-and multiple-tract percutaneous nephrolithotomy for staghorn calculi

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World Journal of Clinical Cases 2024年第7期12卷 1243-1250页

作者： Rui-Xiang cheng Ni dai Yan-min Wang Pei Qi Fen chen Department of Urology Wuhan Ninth HospitalWuhan 430081Hubei ProvinceChina Department of Urinary Pain Wuhan Hankou HospitalWuhan 430000Hubei ProvinceChina Pre-hospital Emergency Department Wuhan Puren HospitalWuhan 430081Hubei ProvinceChina Department of Orthopedic Trauma Surgery Wuhan Hankou HospitalWuhan 430000Hubei ProvinceChina Department of Ultrasound Hubei Provincial Hospital of Integrated Traditional Chinese and Western MedicineWuhan 430015Hubei ProvinceChina

BACKGROUND It is possible that this condition will lead to urosepsis and progressive deterioration of renal function in the absence of surgical *** recent clinical studies have shown that multi-tract percutaneous nephrolithotomy(MPCNL)has a similar stone free rate(SFR)as standard percutaneous nephrolithotomy(S-PCNL).As a result,M-PCNL was also recommended as a treatment option for staghorn *** To examine the perioperative and long-term results of ultrasonography-guided single-and *** This was a retrospective cohort *** March 2021 and January 2022,the urology department of our hospital selected patients for the treatment of staghorn calculi using percutaneous *** primary outcomes were com plication rate and SFR,and the characteristics of patients,operative parameters,laboratory measurements were also *** In total,345 patients were enrolled in the study(186 in the S-PCNL group and 159 in the M-PCNL group).The SFR in the M-PCNL group was significantly higher than that in the S-PCNL group(P=0.033).Moreover,the incidence rates of hydrothorax(P=0.03)and postoperative infection(P=0.012)were higher in the M-PCNL group than in the S-PCNL *** regression analysis demonstrated that post-operative white blood cell count(OR=2.57,95%CI:1.90-3.47,P<0.001)and stone size(OR=1.59,95%CI:1.27-2.00,P<0.001)were associated with a higher overall complication rate in the S-PCNL *** mass index(OR=1.22,95%CI:1.06-1.40,P=0.004)and stone size(OR=1.70,95%CI:1.35-2.15,P<0.001)were associated with increased overall complications in the M-PCNL *** Multiple access tracts can facilitate higher SFR while slightly increasing the incidence of acceptable complications.

关键词： Single-tract percutaneous nephrolithotomy Multiple-tract percutaneous nephrolithotomy Staghorn calculi Ultrasonography

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The Influence of the Sun and Moon on the Observation of Very High Energy Gamma-ray Sources Using EAS Arrays

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Research in Astronomy and Astrophysics 2024年第6期24卷 245-252页

作者： Tao Wen Songzhan chen Benzhong dai School of Physics and Astronomy Yunnan UniversityKunming 650091China Key Laboratory of Particle Astrophysics Institute of High Energy PhysicsChinese Academy of SciencesBeijing 100049China Tianfu Cosmic Ray Research Center Chengdu 610000China

With great advance of ground-based extensive air shower arrays,such as LHAASO and HAWC,many very high energy(VHE)gamma-ray sources have been discovered and are being monitored regardless of the day and the ***,the Sun and Moon would have some impacts on the observation of gamma-ray sources,which have not been taken into account in previous *** this paper,the influence of the Sun and Moon on the observation of very high energy gamma-ray sources when they are near the line of sight of the Sun or Moon is *** tracks of all the known VHE sources are scanned and several VHE sources are found to be very close to the line of sight of the Sun or Moon during some *** absorption of very high energy gamma rays by sunlight is estimated with detailed method and some useful conclusions are *** main influence is the block of the Sun and Moon on gamma rays and the shadow on the cosmic ray *** influence is investigated considering the detector angular resolution and some strategies on data analysis are proposed to avoid the underestimation of the gamma-ray emission.

关键词： astroparticle physics Sun:general methods:observational Sun:UV radiation

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Extracorporeal membrane oxygenation as a bridging therapy for patients with thiamine deficiency-induced pulmonary arterial hypertension

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World Journal of Emergency Medicine 2024年第2期15卷 147-149页

作者： Fangfang Qiu Weixing dai Tengyue Huang min Li Department of Intensive Care Unit the Fourth Affiliated Hospital of Zhejiang University School of MedicineYiwu 322000China Department of Intensive Care Unit the Second Affiliated Hospital of Zhejiang University School of MedicineHangzhou 310009China

Thiamine deficiency is characterized by a deficiency of thiamine(vitamin B1),lactic acidosis,pulmonary arterial hypertension(PAH),right-sided heart failure,and peripheral nerve *** deficiency is easily misdiagnosed and missed during clinical practice and is associated with death in severe cases.[1,2]Here we reported a patient who was admitted to the hospital with severe metabolic acidosis and pulmonary hypertension and finally diagnosed with thiamine deficiency by detecting plasma vitamin B1 *** clinically obvious thiamine deficiency is rare,and cases of thiamine deficiency requiring extracorporeal membrane oxygenation(ECMO)treatment are rarer,we believe that our case will be helpful for emergency clinicians.

关键词： vitamin hypertension arterial

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Prediction of suitable water content in granulation of sintering mixture based on Litster's model

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Journal of Iron and Steel Research International 2024年第3期31卷 552-560页

作者： Fang-lei dai Xiao-hui Fan Xiao-xian Huang Xu-ling chen min Gan Zhi-yun Ji Zeng-qing Sun School of minerals Processing and Bioengineering Central South UniversityChangsha 410083HunanChina

Suitable water content plays a decisive role in the granulation of sintering ***,a method was proposed to predict the suitable water content for effective granulation on the basis of Litster's granulation *** granulation effectiveness of a sintering mixture was predicted by the model,with the allowance error of±10%.The effects of the water absorption properties,particle size composition and content of adhesive particles on the suitable water content were *** results showed that the allowable error of prediction was within±0.5%compared to the experimentally determined suitable water *** an increase in adhesive powder content of mixtures with higher water absorption,the suitable water content increased to achieve similar granulation ***,as the amount of concentrates increased,the suitable water content first increased and then remained *** influence of the water absorption characteristics of the adhesive particles on the suitable water content was less than that of their particle size composition in the mixture.

关键词： Adhesive particle Sintering mixture Granulation effectiveness Suitable water content

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