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Unmanned Aerial Vehicles General Aerial Person-Vehicle Recognition Based on Improved YOLOv8s Algorithm
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作者 zhijian liu 《Computers, Materials & Continua》 SCIE EI 2024年第3期3787-3803,共17页
Considering the variations in imaging sizes of the unmanned aerial vehicles(UAV)at different aerial photography heights,as well as the influence of factors such as light and weather,which can result in missed detectio... Considering the variations in imaging sizes of the unmanned aerial vehicles(UAV)at different aerial photography heights,as well as the influence of factors such as light and weather,which can result in missed detection and false detection of the model,this paper presents a comprehensive detection model based on the improved lightweight You Only Look Once version 8s(YOLOv8s)algorithm used in natural light and infrared scenes(L_YOLO).The algorithm proposes a special feature pyramid network(SFPN)structure and substitutes most of the neck feature extraction module with the Special deformable convolution feature extraction module(SDCN).Moreover,the model undergoes pruning to eliminate redundant channels.Finally,the non-maximum suppression algorithm of intersection-union ratio based on minimum point distance(MPDIOU_NMS)algorithm has been integrated to eliminate redundant detection boxes,and a comprehensive validation has been conducted using the infrared aerial dataset and the Visdrone2019 dataset.The comprehensive experimental results demonstrate that when the number of parameters and floating-point operations is reduced by 30%and 20%,respectively,there is a 1.2%increase in mean average precision at a threshold of 0.5(mAP(0.5))and a 4.8%increase in mAP(0.5:0.95)on the infrared dataset.Finally,the mAP on the Visdrone2019 dataset has experienced an average increase of 12.4%.The accuracy and recall rates have seen respective increases of 9.2%and 3.6%. 展开更多
关键词 YOLOv8s SPFN SDCN PRUNING MPDIOU_NMS
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Application of Wavelength Selection Combined with DS Algorithm for Model Transfer between NIR Instruments
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作者 Honghong Wang Zhixin Xiong +2 位作者 Yunchao Hu zhijian liu Long Liang 《Journal of Renewable Materials》 SCIE EI 2023年第6期2713-2727,共15页
This study aims to realize the sharing of near-infrared analysis models of lignin and holocellulose content in pulp wood on two different batches of spectrometers and proposes a combined algorithm of SPA-DS,MCUVE-DS a... This study aims to realize the sharing of near-infrared analysis models of lignin and holocellulose content in pulp wood on two different batches of spectrometers and proposes a combined algorithm of SPA-DS,MCUVE-DS and SiPLS-DS.The Successive Projection Algorithm(SPA),the Monte-Carlo of Uninformative Variable Elimination(MCUVE)and the Synergy Interval Partial Least Squares(SiPLS)algorithms are respectively used to reduce the adverse effects of redundant information in the transmission process of the full spectrum DS algorithm model.These three algorithms can improve model transfer accuracy and efficiency and reduce the manpower and material consumption required for modeling.These results show that the modeling effects of the characteristic wavelengths screened by the SPA,MCUVE and SiPLS algorithms are all greatly improved compared with the full-spectrum modeling,in which the SPA-PLS result in the best prediction with RPDs above 6.5 for both components.The three wavelength selection methods combined with the DS algorithm are used to transfer the models of the two instruments.Among them,the MCUVE combined with the DS algorithm has the best transfer effect.After the model transfer,the RMSEP of lignin is 0.701,and the RMSEP of holocellulose is 0.839,which was improved significantly than the full-spectrum model transfer of 0.759 and 0.918. 展开更多
关键词 Near infrared spectroscopy HOLOCELLULOSE LIGNIN model transfer wavelength optimization direct standardization algorithm
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经脐单孔+1孔腹腔镜结直肠癌根治术的可行性研究 被引量:9
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作者 范琳峰 刘志坚 +3 位作者 曾翔辉 赖剑 赵书锋 曾祥福 《中国肿瘤临床》 CAS CSCD 北大核心 2020年第11期567-570,共4页
目的:探讨经脐单孔+1孔腹腔镜(single-incision plus one-port laparoscopic surgery,SILS+1)结直肠癌根治术的安全性及可行性。方法:回顾性分析2017年10月至2019年11月赣南医学院第一附属医院收治的8例进行经脐SILS+1结直肠癌根治术患... 目的:探讨经脐单孔+1孔腹腔镜(single-incision plus one-port laparoscopic surgery,SILS+1)结直肠癌根治术的安全性及可行性。方法:回顾性分析2017年10月至2019年11月赣南医学院第一附属医院收治的8例进行经脐SILS+1结直肠癌根治术患者的临床资料。结果:8例结直肠癌患者手术均顺利完成,无中转开腹及增加戳卡孔数量,手术平均时间107(95~124)min,平均出血33(10~80)mL,2例患者出现术后发热,考虑术后吸收热可能,术后第3天自行退热,其余患者术后无明显外科并发症,术后1~3天胃肠道功能恢复,3~5天拔出腹腔引流管,术后住院时间约9.3(7~11)天。术后病理再次证实为结直肠腺癌,淋巴结检出平均数目为13.6(11~16)枚,均无围手术期严重并发症及死亡的发生。术后随访3~24个月,平均10个月,未发现肿瘤局部复发、腹壁戳孔切口种植转移。结论:经脐SILS+1结直肠癌根治术安全可行,创伤小,美容效果令人满意,但远期疗效有待进一步观察。 展开更多
关键词 经脐 单孔+1孔 腹腔镜 结直肠癌
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锰锌铁氧致密化烧结原理及方法
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作者 尉晓东 刘志坚 +2 位作者 侯海彬 杨权平 赖焜 《陶瓷》 CAS 2021年第8期41-44,共4页
分析了致密化烧结的原理,推导出了致密化阶段铁氧体的理论放氧量,提出和分析了了通常的致密化烧结工艺方法。
关键词 锰锌铁氧体 致密化烧结 放氧
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相对湿度和散发源位置对某典型城市环境生物气溶胶迁移规律特性的影响 被引量:1
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作者 董志坚 刘志坚 +5 位作者 胡晨星 叶成林 陈立 迟海鹏 贺宇辰 戎瑞 《科学通报》 EI CAS CSCD 北大核心 2024年第7期842-853,共12页
近年来,城市生物安全问题受到国家和人民的高度关注,其中以生物气溶胶为载体的空气动力学迁移机制尚不完全清晰,因此无法实现该问题的精准防控.本研究重点关注了城市区域相对湿度(relative humidity,RH)和生物气溶胶释放位置(建筑上游... 近年来,城市生物安全问题受到国家和人民的高度关注,其中以生物气溶胶为载体的空气动力学迁移机制尚不完全清晰,因此无法实现该问题的精准防控.本研究重点关注了城市区域相对湿度(relative humidity,RH)和生物气溶胶释放位置(建筑上游空旷区和密集区)对下游相近位置(高密度区和低密度区)生物气溶胶迁移规律的影响.研究表明:随着RH增加,沿来流方向的行人高度水平方向和建筑所在区域竖直方向的流场逐渐减弱.RH和生物气溶胶释放位置对生物气溶胶的迁移和沉积有双重影响.(1)在两种不同释放位置下,随RH增加,生物气溶胶的横向迁移范围均增加,高密度区水平和竖直方向的生物气溶胶浓度均高于低密度区.(2)与密集区释放相比,在空旷区释放的生物气溶胶沿来流方向的横向迁移范围较小,迁移距离更长.(3)在两种不同释放位置下,随着RH增加,在空旷区释放工况下建筑表面的总沉积比略微增加;密集区释放工况下建筑表面总沉积比先降低后增加.本研究结果为防控和应对以生物气溶胶等为载体的城市生物安全问题提供了合理的流体力学理论支撑. 展开更多
关键词 城市环境 生物气溶胶 相对湿度 释放位置 迁移规律
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Interpenetrating LiB/Li_(3)BN_(2) phases enabling stable composite lithium metal anode
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作者 Piao Qing Shaozhen Huang +11 位作者 Tuoya Naren Quan Li Haifeng Huang Kecheng Long zhijian liu Lin Mei Fu Sun Weifeng Wei Yu Zhang Jianmin Ma Zhibin Wu Libao Chen 《Science Bulletin》 SCIE EI CAS CSCD 2024年第18期2842-2852,共11页
Host-less lithium metal anode generally suffers from large volume changes and serious dendrite growth during cycling,which poses challenges for its practical application.Interpenetrating phase composites with continuo... Host-less lithium metal anode generally suffers from large volume changes and serious dendrite growth during cycling,which poses challenges for its practical application.Interpenetrating phase composites with continuous architectures offer a solution to enhance mechanical properties of materials.Herein,a robust composite Li anode(LBN)material is fabricated through the metallurgical reaction between Li and hexagonal boron nitride(h-BN)with the formation of interpenetrating LiB/Li_(3)BN_(2)phases.As LiB fibers are anchored by Li_(3)BN_(2)granules,the collapse and slippage of LiB fibers are suppressed whilst the mechanical strength and structural stability of LBN are reinforced.By rolling,ultrathin(15μm),freestanding,and electrochemically stable LBN foil can be obtained.The LBN anode exhibits a high average Coulombic efficiency of 99.69%(1 mA cm^(-2),3 mAh cm^(-2))and a long lifespan of 2500 h(1 mA cm^(-2),1 m Ah cm^(-2)).Notably,the LiCoO_(2)(with double-sided load 40 mg cm^(-2))|LBN pouch cell can operate over450 cycles with a capacity retention of 90.1%.The exceptional cycling stability of LBN can be ascribed to the interpenetrating reinforcement architectures and synergistic electronic/ionic conductivity of the LiB/Li_(3)BN_(2)dual-lithiophilic-phases.This work provides a new methodology for thin Li strip processing and reinforced-architecture design,with implications beyond battery applications. 展开更多
关键词 Li metal anode ULTRATHIN Interpenetrating Li-B alloy Li_(3)BN_(2)
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Telomere-to-telomere genome assemblies of two Chinese Baijiu-brewing sorghum landraces
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作者 Jiandong Bao Heng Zhang +9 位作者 Fulin Wang Lin Li Xueming Zhu Junfeng Xu Yao Wang zhijian liu Guowei Zhai Heng Xu Fucheng Lin Ying Zhu 《Plant Communications》 SCIE CSCD 2024年第6期9-12,共4页
Dear Editor,Sorghum(Sorghum bicolor[L.]Moench)(2n=20),a C4 droughttolerant cereal crop,is widely cultivated for food,feed,and biofuel,resulting in varieties with distinct morphological characteristics.The Sanger-seque... Dear Editor,Sorghum(Sorghum bicolor[L.]Moench)(2n=20),a C4 droughttolerant cereal crop,is widely cultivated for food,feed,and biofuel,resulting in varieties with distinct morphological characteristics.The Sanger-sequencing-based sorghum reference genome of the inbred variety BTx623(grain sorghum)was initially released in 2009(base error<1 per 10 kb)(Paterson et al.,2009),and the most widely used version 3 assembly(base error<1 per 100 kb),consisting of 4773 contigs with 2679 unresolved gaps(~28 Mb)in 10 chromosomes,was improved by next-generation sequencing in 2017(McCormick et al.,2018). 展开更多
关键词 SORGHUM CULTIVATED CEREAL
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Using CONTAM to design ventilation strategy of negative pressure isolation ward considering different height of door gaps
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作者 Mingyao Ma Changsheng Cao +4 位作者 Yukun Xu zhijian liu Lingjie Zeng Chengquan Zhang Jun Gao 《Energy and Built Environment》 2024年第1期32-45,共14页
Infectious disease departments in hospitals require pressure gradient to create unidirectional airflow to prevent the spread of contaminants,typically by creating active air infiltration through the difference between... Infectious disease departments in hospitals require pressure gradient to create unidirectional airflow to prevent the spread of contaminants,typically by creating active air infiltration through the difference between supply and exhaust air volumes.The door gap is the channel of air flow between rooms,so its height has an important influence on the pressure difference and infiltration air volume of the room.There is still a lack of research on setting reasonable ventilation strategies according to the different heights of door gaps at different positions in the building.In this study,model of a set of isolation wards was established and analyzed using the multi-zone simulation software CONTAM,and the ventilation strategies with different heights of door gaps were applied to the actual infection diseases department.The results show that in a building with ventilation system divided by functional area,the difference in the height of the door gaps requires different active infiltration air volumes.Pressure fluctuations in the medical and patient corridors are greater than in other rooms.The significance of this study is to understand the active infiltration of air to guide the design and operation of ventilation systems in infectious disease hospitals or building remodeled to isolate close contacts of COVID-19 patients.It is also instructive for the design of pressure gradients in clean workshops,biological laboratories,and other similar buildings. 展开更多
关键词 Door gap height Active infiltration Pressure gradient Multizone model CONTAM Control strategy
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锰锌铁氧致密化烧结原理及方法
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作者 尉晓东 刘志坚 +2 位作者 侯海彬 杨权平 赖焜 《磁性元件与电源》 2024年第1期160-163,共4页
分析了致密化烧结的原理,推导出了致密化阶段铁氧体的理论放氧量,提出和分析了了通常的致密化烧结工艺方法。
关键词 锰锌铁氧体 致密化烧结 放氧
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The influence of air supply inlet location on the spatial-temporal distribution of bioaerosol in isolation ward under three mixed ventilation modes 被引量:1
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作者 zhijian liu Tianci Wang +2 位作者 Yongxin Wang Haiyang liu Guoqing Cao Song Tang 《Energy and Built Environment》 2023年第4期445-457,共13页
The outbreak of COVID-19 and the spread of infectious pathogens through bioaerosols have once again aroused widespread concern worldwide.Isolation ward is an important place to prevent the spread of infectious bioaero... The outbreak of COVID-19 and the spread of infectious pathogens through bioaerosols have once again aroused widespread concern worldwide.Isolation ward is an important place to prevent the spread of infectious bioaerosols.However,infection of health care workers(HCWs)in the isolation ward often occurs,so it is ur-gent to carry out relevant research to reduce the cross-infection between HCWs and patients.In this paper,the temporal and spatial distribution characteristics of bioaerosols under three mixed ventilation modes in a single ward were studied,namely,upper supply side return air of Case 1 and side supply and side return ventilation are Case 2 and Case 3 respectively.The results show that the removal efficiency of bioaerosol in the ventilation mode of Case 3,in which directional airflow is formed from the air supply inlet to the release source and then to the exhaust outlet,is 46.6%and 67.7%higher than that of Case 1 and Case 2,respectively.In addition,ventilation methods based on mixed theory do not guarantee good air quality in the breathing zone(1.3 m to 1.7 m)of HCWs,which may increase the inhalation risk for HCWs.It is hoped that our results can provide some useful suggestions for optimizing the airflow layout of the isolation ward,reducing the risk of cross-infection,and virus elimination. 展开更多
关键词 BIOAEROSOL Isolation ward Mixed ventilation Breathing zone Computational fluid dynamics
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Prevention of surgical site infection under different ventilation systems in operating room environment 被引量:6
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作者 zhijian liu Haiyang liu +3 位作者 Hang Yin Rui Rong Guoqing Cao Qihong Deng 《Frontiers of Environmental Science & Engineering》 SCIE EI CAS CSCD 2021年第3期63-76,共14页
Biological particles in the operating room(OR)air environment can cause surgical site infections(SSIs).Various ventilation systems have been employed in ORs to ensure an ultraclean environment.However,the effect of di... Biological particles in the operating room(OR)air environment can cause surgical site infections(SSIs).Various ventilation systems have been employed in ORs to ensure an ultraclean environment.However,the effect of different ventilation systems on the control of bacteria-carrying particles(BCPs)released from the surgical staff during surgery is unclear.In this study,the performance of four different ventilation systems(vertical laminar airflow ventilation(VLAF),horizontal laminar airflow ventilation(HLAP),differential vertical airflow ventilation(DVAF),and temperature-controlled airflow ventilation(TAF))used in an OR was evaluated and compared based on the spatial BCP concentration.The airflow field in the OR was solved by the Renormalization Group(RNG)k-e turbulence model,and the BCP phase was calculated by Lagrangian particle tracking(LPT)and the discrete random walk(DRW)model.It was found that the TAF system was the most effective ventilation system among the four ventilation systems for ensuring air cleanliness in the operating area.This study also indicated that air cleanliness in the operating area depended not only on the airflow rate of the ventilation system but also on the airflow distribution,which was greatly affected by obstacles such as surgical lamps and surgical staff. 展开更多
关键词 Operating room(OR) Bacteria-carrying particles(BCPs) Surgical site infections(SSIs) Ventilation
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Dust accumulated fungi in air-conditioning system:Findings based on field and laboratory experiments 被引量:2
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作者 zhijian liu Yuzhu Deng +2 位作者 Shengyuan Ma Bao-Jie He Guoqing Cao 《Building Simulation》 SCIE EI CSCD 2021年第3期793-811,共19页
This study analyzes the growth and reproduction of dust accumulated fungi(DAF)in an air-conditioning system based on field measurement and molecular biology,laboratory experiment and prediction modelling.The field mea... This study analyzes the growth and reproduction of dust accumulated fungi(DAF)in an air-conditioning system based on field measurement and molecular biology,laboratory experiment and prediction modelling.The field measurement was conducted to collect dust in filter screen,surface cooler and air supply duct of two air handling units(AHUs).The results indicate that dust volume and fungal number in two AHUs generally met the hygienic specification of public buildings,but the cleansing did not fulfil requirements.High-throughput sequencing was conducted,revealing that the dominant fungal species were Alternaria_betae-kenyensis,Cladosporium_delicatulum,Aspergillus_sydowii,Verticillium_dahliae.Laboratory experiment was conducted to analyze the impact of several factors(e.g.growth time,temperature,relative humidity,duct material)and their combination on the DAF growth.The results indicate that fungal growth increased with time,peaking at 4 days or 5 days.Higher relative humidity or temperature was conducive to fungal growth.The orthogonal experiment revealed that the condition of“antibacterial composite,22±1℃and 45%-55%RH”had the strongest inhibiting impact on fungal growth.Logistic model,Gompertz model and square-root model were further developed to predict the fungal growth under different conditions.The results show that the Logistic model had high feasibility and accuracy,the Gompertz model was feasible with lower accuracy and the square-root model was feasible with high accuracy.Overall,this study facilitates the understanding of the DAF growth in air-conditioning ducts,which is important for real-time prediction and timely control of the fungal contamination. 展开更多
关键词 dust accumulated fungi high-throughput sequencing air supply duct duct material orthogonal experiment fungal growth prediction
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Transmission of 200 Tb/s (375 × 3 × 178.125 Gb/s) PDM-DFTS-OFDM-32QAM super channel over lkm FMF 被引量:1
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作者 Ming LUO Qi MO +11 位作者 Xiang LI Rong HU Ying QIU Cai LI zhijian liu Wu liu Huang YU Wei DU Jing XU Zhixue HE Qi YANG Shaohua YU 《Frontiers of Optoelectronics》 CSCD 2015年第4期394-401,共8页
A few-mode fiber (FMF) is designed to support three spatial modes (LP01, LP 11a, and LP 11 b) and fabricated through plasma chemical vapor deposition (PCVD)and rod-in-tube (RIT) method. Using PDM-DFTS-OFDM- 32... A few-mode fiber (FMF) is designed to support three spatial modes (LP01, LP 11a, and LP 11 b) and fabricated through plasma chemical vapor deposition (PCVD)and rod-in-tube (RIT) method. Using PDM-DFTS-OFDM- 32QAM modulation, wavelength division multiplexing, mode multiplexing, and coherent detection, we successfully demonstrated 200Tb/s (375× 3 × 178.125Gb/s) signal over 1 km FMF using C and L bands with 25 GHz channel spacing. After 1 km FMF transmission, all the tested bit error rates (BERs) are below 20% forward error correction (FEC) threshold (2.0 × 10-2). Within each sub-channel, we achieved a spectral efficiency of 21.375 bits/Hz in the C and L bands. 展开更多
关键词 few-mode fiber (FMF) mode multiplexing coherent detection
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MiRNA-203 suppresses tumor cell proliferation, migration and invasion by targeting Slug in gastric cancer 被引量:7
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作者 liuqing Yang Hongwei Liang +11 位作者 Yanbo Wang Shanting Gao Kai Yin zhijian liu Xi Zheng Ying Lv Lei Wang Chen-Yu Zhang Xi Chen Guifang Xu Weijie Zhang Xiaoping Zou 《Protein & Cell》 SCIE CAS CSCD 2016年第5期383-387,共5页
Snail, a family of zinc finger transcription factors, plays an important role in morphogenesis and embryogenesis. Snail zinc finger family 2 (SNAI2 or Slug) has been demonstrated to regulate carcinogenesis of severa... Snail, a family of zinc finger transcription factors, plays an important role in morphogenesis and embryogenesis. Snail zinc finger family 2 (SNAI2 or Slug) has been demonstrated to regulate carcinogenesis of several human cancers including breast, prostate, head, neck, 展开更多
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The influence of home environmental factors and life style on children's respiratory health in Xi'an
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作者 Angui Li Yuexia Sun +3 位作者 zhijian liu Xiaoxia Xu Hongfa Sun Jan Sundell 《Chinese Science Bulletin》 SCIE EI CAS 2014年第17期2024-2030,共7页
To assess associations between home indoor air environments and asthma,allergies and pneumonia,children aged 1–8 years were surveyed from 12 kindergartens in the city of Xi’an.2,020 questionnaires were responded wit... To assess associations between home indoor air environments and asthma,allergies and pneumonia,children aged 1–8 years were surveyed from 12 kindergartens in the city of Xi’an.2,020 questionnaires were responded with a response rate of 83.5%.The prevalences of doctor diagnosed asthma,hay fever,and pneumonia were 2.9%,3.6%,and 28.3%,respectively.Living close to a highway was a risk factor for current rhinitis(AOR 1.5,95%CI 1.2–1.8),eczema(AOR 1.7,95%CI 1.2–2.5),and diagnosed pneumonia(AOR 1.3,95%CI 1.0–1.6).Dampness problems in the home were associated with 50%–130%increases in the prevalences of asthma and allergy.Airing bed linen under sun-shine was protective,especially against rhinitis.Pet avoidance was consistently and significantly associated with asthma and allergy(AOR 1.3–2.4).Decoration of the home during children’s early life is a risk factor for current rhinitis(AOR 1.9,95%CI 1.3–2.9)and eczema(AOR 1.9,95%CI1.1–3.6).Risk factors for pneumonia were living in an apartment(AOR 1.4,95%CI 1.1–1.8),latex wall paint(AOR 1.3,95%CI 1.0–1.7),dampness(AOR 1.4–1.5),breast feeding\3 months(AOR 1.3,95%CI 1.0–1.7),never airing bed linen in sunshine(AOR 1.3,95%CI1.3–1.6),and cleaning children’s room less frequently than once per day(AOR 1.4,95%CI 1.1–1.7).This study demonstrates that home indoor environmental and life style factors may influence the health of children in Xi’an. 展开更多
关键词 呼吸系统健康 生活方式 家庭化 西安市 环境因素 儿童 室内空气环境 危险因素
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Viral metagenomics analysis of feces from coronary heart disease patients reveals the genetic diversity of the Microviridae
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作者 Lianghua Guo Xiuguo Hua +9 位作者 Wen Zhang Shixing Yang Quan Shen Haibing Hu Jingjiao Li zhijian liu Xiaochun Wang Hua Wang Chenglin Zhou Li Cui 《Virologica Sinica》 SCIE CAS CSCD 2017年第2期130-138,共9页
Recent studies have declared that members of the ss DNA virus family Microviridae play an important role in multiple environments, as they have been found taking a dominant position in the human gut. The aim of this s... Recent studies have declared that members of the ss DNA virus family Microviridae play an important role in multiple environments, as they have been found taking a dominant position in the human gut. The aim of this study was to analyze the overall composition of the gut virome in coronary heart disease(CHD) patients, and try to discover the potential link between the human gut virome and CHD. Viral metagenomics methods were performed to detect the viral sequences in fecal samples collected from CHD inpatients and healthy persons as controls. We present the analysis of the virome composition in these CHD patients and controls. Our data shows that the virome composition may be linked to daily living habits and the medical therapy of CHD.Virgaviridae and Microviridae were the two dominant types of viruses found in the enteric virome of CHD patients. Fourteen divergent viruses belonging to the family Microviridae were found, twelve of which were grouped into the subfamily Gokushovirinae, while the remaining two strains might represent two new subfamilies within Microviridae, according to the phylogenetic analysis. In addition, the genomic organization of these viruses has been characterized. 展开更多
关键词 gut virome coronary heart disease (CHD) viral metagenomics Microviridae Gokushovirinae
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Quantitative distribution of human exhaled particles in a ventilation room
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作者 zhijian liu Hangyao Zhu +1 位作者 Yangfan Song Guoqing Cao 《Building Simulation》 SCIE EI CSCD 2022年第5期859-870,共12页
Respiratory viruses can be attached to human exhaled particles and spread from person to person through respiratory activities.The purpose of this study is to obtain the quantitative description formula of human exhal... Respiratory viruses can be attached to human exhaled particles and spread from person to person through respiratory activities.The purpose of this study is to obtain the quantitative description formula of human exhaled particles in the ventilated room through amount number of numerical simulation calculations and regression statistical analysis of the simulated data.In this study,a combination of numerical simulation and laboratory experiments was used,and the results were tallied preferably.Bacillus subtilis was released as a release source to investigate the migration and distribution of bioaerosol.The results show that under the condition of high air supply velocity,due to the disturbance of human respiration and airflow,the diffusion velocity of exhaled particles was faster and the diffusion range is larger than that of low air supply velocity within the same time frame.No matter where the location of the manikin was in the room,the exhaled particles would spread to the whole room in at least 900 s.The method used in this study could be used to predict the distribution of human exhaled particles concentration in different indoor spaces,such as public transport and hospitals.These findings could provide valuable reference for the location of indoor air purifiers,which plays a guiding role in the construction of a healthy indoor environment. 展开更多
关键词 droplet aerosols particulate concentrations bioaerosol release experiment CFD predictions
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NR类合金粉芯研究
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作者 侯海彬 刘志坚 +2 位作者 尉晓东 杨权平 赖焜 《磁性元件与电源》 2022年第3期170-171,178,共3页
采用改性有机硅树脂和低温绝缘玻璃粉对铁硅铬合金粉进行表面绝缘处理,制做NR类合金粉芯,通过高温烧结,低温玻璃粉熔融,形成薄膜覆盖在粉体表层,有机硅树脂分解为SiO_(2),分散在粉体间,起到隔离各金属粉体颗粒接触作用,提高其表面电阻,... 采用改性有机硅树脂和低温绝缘玻璃粉对铁硅铬合金粉进行表面绝缘处理,制做NR类合金粉芯,通过高温烧结,低温玻璃粉熔融,形成薄膜覆盖在粉体表层,有机硅树脂分解为SiO_(2),分散在粉体间,起到隔离各金属粉体颗粒接触作用,提高其表面电阻,最终使NR类磁芯能够电镀的目的。采取不同配方进行验证:1.确定合金磁粉中改性有机硅树脂和低温绝缘玻璃粉的加入配比,与磁芯烧结温度相匹配;2.研究热处理工艺,使改性有机硅树脂和低温绝缘玻璃粉完全熔融和分解,最佳效果是低温玻璃粉在金属粉体表面成膜,有机硅树脂分解为SiO_(2)或单质Si。同时,也使磁芯表面合金氧化,形成一层薄而均匀致密的氧化铬层,提高磁芯的绝缘度和耐磨性。3.研究电镀工艺参数,确定一个适合合金磁粉芯产品的电镀工艺,降低电镀液的酸度和电镀时间,减少对磁芯的腐蚀。结合本文章申请的专利,来保护磁芯表面的包覆层和氧化层不被破坏掉,电镀不扩散。 展开更多
关键词 铁硅铬合金粉 低温绝缘玻璃粉 有机硅树脂 NR合金粉芯 包覆 烧结
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