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Gapless genome assembly of azalea and multi-omics investigation into divergence between two species with distinct f lower color 被引量:4
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作者 Shuai Nie Shi-Wei Zhao +15 位作者 Tian-Le Shi Wei Zhao Ren-Gang Zhang Xue-Chan Tian Jing-Fang Guo Xue-Mei Yan Yu-Tao Bao Zhi-Chao Li lei kong Hai-Yao Ma Zhao-Yang Chen Hui Liu Yousry AEl-Kassaby Ilga Porth Fu-Sheng Yang Jian-Feng Mao 《Horticulture Research》 SCIE CSCD 2023年第1期193-206,共14页
The genus Rhododendron(Ericaceae),with more than 1000 species highly diverse in f lower color,is providing distinct ornamental values and a model system for f lower color studies.Here,we investigated the divergence be... The genus Rhododendron(Ericaceae),with more than 1000 species highly diverse in f lower color,is providing distinct ornamental values and a model system for f lower color studies.Here,we investigated the divergence between two parental species with different f lower color widely used for azalea breeding.Gapless genome assembly was generated for the yellow-f lowered azalea,Rhododendron molle.Comparative genomics found recent proliferation of long terminal repeat retrotransposons(LTR-RTs),especially Gypsy,has resulted in a 125 Mb(19%)genome size increase in species-specific regions,and a significant amount of dispersed gene duplicates(13402)and pseudogenes(17437).Metabolomic assessment revealed that yellow f lower coloration is attributed to the dynamic changes of carotenoids/f lavonols biosynthesis and chlorophyll degradation.Time-ordered gene co-expression networks(TO-GCNs)and the comparison confirmed the metabolome and uncovered the specific gene regulatory changes underpinning the distinct f lower pigmentation.B3 and ERF TFs were found dominating the gene regulation of carotenoids/f lavonols characterized pigmentation in R.molle,while WRKY,ERF,WD40,C2H2,and NAC TFs collectively regulated the anthocyanins characterized pigmentation in the red-f lowered R simsii.This study employed a multi-omics strategy in disentangling the complex divergence between two important azaleas and provided references for further functional genetics and molecular breeding. 展开更多
关键词 DIVERGENCE YELLOW COLLECTIVE
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Investigating the Changes in Air Pollutant Emissions over the Beijing-Tianjin-Hebei Region in February from 2014 to 2019 through an Inverse Emission Method 被引量:1
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作者 Xuechun LUO Xiao TANG +8 位作者 Haoyue WANG lei kong Huangjian WU Weiguo WANG Yating SONG Hongyan LUO Yao WANG Jiang ZHU Zifa WANG 《Advances in Atmospheric Sciences》 SCIE CAS CSCD 2023年第4期601-618,共18页
In recent years,China has implemented several measures to improve air quality.The Beijing-Tianjin-Hebei(BTH)region is one area that has suffered from the most serious air pollution in China and has undergone huge chan... In recent years,China has implemented several measures to improve air quality.The Beijing-Tianjin-Hebei(BTH)region is one area that has suffered from the most serious air pollution in China and has undergone huge changes in air quality in the past few years.How to scientifically assess these change processes remain the key issue in further improving the air quality over this region in the future.To evaluate the changes in major air pollutant emissions over this region,this paper employs ensemble Kalman filtering(EnKF)for integrating the national ground monitoring pollutant observation data and the Nested Air Quality Prediction Modeling System(NAQPMS)simulation data to inversely estimate the emission rates of SO_(2),NOX,CO,and primary PM_(2.5)over BTH region in February from 2014 to 2019.The results show that SO_(2),NOX,CO,and primary PM_(2.5)emissions in the BTH region decreased in February from 2014 to 2019 by 83%,37%,41%,and 42%,while decreases in Beijing during this period were 86%,67%,59%,and 65%,respectively.Compared with the prior emission inventory,the inversion emission inventory reduces the uncertainty of multi-pollutant simulation in the BTH region,with simulated root mean square errors of the monthly average concentrations of SO_(2),NOX,PM_(2.5),and CO reduced by 41%,30%,31%,and 22%,respectively.The average uncertainties of SO_(2),NOX,PM_(2.5),and CO inversion emissions in2014-19 are±14.03%yr^(-1),±28.91%yr^(-1),±126.15%yr^(-1),and±43.58%yr^(-1).Compared with the uncertainty of MEIC emission,the uncertainties of all species changed by+2%yr^(-1),-2%yr^(-1),-26%yr^(-1),and-4%yr^(-1),respectively.The spatial distribution results illustrate that air pollutant emissions are mainly distributed over the eastern and southern BTH regions.The spatial gap between the inversion emissions and MEIC emissions was further closed in 2019 compared to 2014.The results of this paper can provide a new reference for assessing changes in air pollution emissions over the BTH region in recent years and validating a bottom-up emission inventory. 展开更多
关键词 emission inversion emission trend air pollutants BEIJING-TIANJIN-HEBEI
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Efficacy of invisible advancement correction for mandibular retraction in adolescents based on Pancherz analysis 被引量:1
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作者 lei kong Xin-Qiang Liu 《World Journal of Clinical Cases》 SCIE 2023年第6期1299-1309,共11页
BACKGROUND Mandibular retraction is the main etiological mechanism of class II malocclusion in China and the subsequent distal molar relationship can cause functional discomfort in mastication,breathing and the tempor... BACKGROUND Mandibular retraction is the main etiological mechanism of class II malocclusion in China and the subsequent distal molar relationship can cause functional discomfort in mastication,breathing and the temporomandibular joint.The use of mandibular advancement(MA)devices has recently emerged as an adolescent mandibular retraction treatment;however,current studies regarding the effect thereof are relatively few,and there is lack of sufficient clinical support.AIM To investigate the clinical effect of invisalign MA on the treatment of mandibular retraction in adolescents.METHODS This study included 30 adolescent patients who underwent treatment with the MA appliances from December 2017 to June 2021.The lateral cephalometric data before and after treatment were collected and imported into Dolphin Imaging software.The changes were measured by linear measurement superimposed with lateral cephalometric trajectory based on the Pancherz technology.RESULTS There was no significant difference in the length and position of maxilla before and after the treatment.The position of the mandible moved 3.13 mm,the length increased 4.14 mm,the mandibular ramus length increased 4.09 mm,the body length increased 4.25 mm,and the position of the condyle moved 1.03 mm forward after treatment.Additionally,changes in the incisor sagittal position and labial inclination were observed.The position of the upper incisor point moved back 1.33 mm,without statistical difference,the inclination and tooth angle decreased by 3.44°and 4.06°,respectively;the position of the lower incisor point was moved 2.98 mm,and the inclination and tooth angle increased by 2.62°and 1.23°,respectively.Furthermore,changes in the incisor overjet and molar relationship were seen.Overjet decreased by 4.31 mm,of which 1.78 mm was due to dental factors,accounting for 41.3%of the effect as opposed to 58.7%due to skeletal factors.Molar relationship improved 3.87 mm,with 1.34 mm due to dental factors,and dental and skeletal factors were accounted for 34.6%and 65.4%of the effect,respectively.CONCLUSION For adolescent patients with mandible retraction,invisalign MA can effectively promote the mandible growth,and it was proven to be mainly due to skeletal effects. 展开更多
关键词 Mandibular retraction ADOLESCENT Pancherz technology Functional correction Invisible appliance Mandibular advancement
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ADSC-Exos outperform BMSC-Exos in alleviating hydrostatic pressure-induced injury to retinal ganglion cells by upregulating nerve growth factors
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作者 Zhi-Kun Zheng lei kong +2 位作者 Min Dai Yi-Dan Chen Yan-Hua Chen 《World Journal of Stem Cells》 SCIE 2023年第12期1077-1092,共16页
BACKGROUND Mesenchymal stem cells(MSCs)have protective effects on the cornea,lacrimal gland,retina,and photoreceptor cell damage,which may be mediated by exosomes(exos)released by MSCs.AIM To investigate the ameliorat... BACKGROUND Mesenchymal stem cells(MSCs)have protective effects on the cornea,lacrimal gland,retina,and photoreceptor cell damage,which may be mediated by exosomes(exos)released by MSCs.AIM To investigate the ameliorating effect of exos derived from different MSCs on retinal ganglion cell(RGC)injury induced by hydrostatic pressure.METHODS The RGC injury model was constructed by RGC damage under different hydrostatic pressures(40,80,120 mmHg).Then RGCs were cultured with adipose-derived stem cell(ADSC)-Exos and bone marrow-derived stem cell(BMSC)-Exos.Cell Counting Kit-8,transmission electron microscopy,flow cytometry,immunofluorescence,real-time quantitative polymerase chain reaction,and western blotting were performed to detect the ameliorating effect of exos on pressure-induced RGC injury.RESULTS ADSC-Exos and BMSC-Exos were successfully isolated and obtained.The gibbosity of RGCs was lower,the cells were irregularly ellipsoidal under pressure,and the addition of ADSC-Exos and BMSC-Exos significantly restored RGC morphology.Furthermore,the proliferative activity of RGCs was increased and the apoptosis of RGCs was inhibited.Moreover,the levels of lactate dehydrogenase and apoptosis-related proteins were increased,and the concentrations of antiapoptotic proteins and neurotrophic factors were decreased in damaged RGCs.However,the above indicators were significantly improved after ADSC Exos and BMSC-Exos treatment.CONCLUSION These findings indicated that ADSC-Exos and BMSC-Exos could ameliorate RGC injury caused by hydrostatic pressure by inhibiting apoptosis and increasing the secretion of neurotrophic factors. 展开更多
关键词 Adipose-derived stem cells Bone marrow-derived stem cells EXOSOMES GLAUCOMA
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连续碳纤维增强阴离子聚酰胺 6热塑性复合材料的制备与性能 被引量:4
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作者 孙福瑞 纪高宁 +7 位作者 朱世鹏 杨云华 冯志海 马壮 左小彪 孔磊 王伟 陈金耀 《高分子材料科学与工程》 EI CAS CSCD 北大核心 2022年第9期45-50,共6页
采用树脂传递模塑工艺(RTM)制备了阴离子聚酰胺6树脂和连续碳纤维(CF)增强阴离子聚酰胺6(APA6)热塑性复合材料,研究了催化剂配比对APA6树脂转化率、结晶度和力学性能的影响。进一步探讨了纤维体积分数对连续CF/APA6复合材料力学性能的影... 采用树脂传递模塑工艺(RTM)制备了阴离子聚酰胺6树脂和连续碳纤维(CF)增强阴离子聚酰胺6(APA6)热塑性复合材料,研究了催化剂配比对APA6树脂转化率、结晶度和力学性能的影响。进一步探讨了纤维体积分数对连续CF/APA6复合材料力学性能的影响,并采用扫描电镜(SEM)观察了复合材料的拉伸断裂形貌。结果表明,APA6树脂转化率和结晶度随着催化剂比例增大而降低;当纤维体积分数为40%时,连续CF/APA6复合材料的拉伸强度和弹性模量最高分别达到493 MPa和60 GPa;SEM分析表明,继续增加纤维体积分数(>40%),APA6树脂基体在碳纤维中的浸润性变差,弱化的界面使增强体作用难以发挥。 展开更多
关键词 碳纤维 阴离子聚酰胺6 热塑性复合材料
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Analysis of risk factors for polypoid lesions of gallbladder among health examinees 被引量:25
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作者 Hua-Li Yang Hui-Fang Shen +6 位作者 Yu Wang Xin-Gang Gu Jian-Min Qin Pei-Hao Yin Qi Li lei kong Li-Li Hou 《World Journal of Gastroenterology》 SCIE CAS CSCD 2012年第23期3015-3019,共5页
AIM: To investigate the prevalence and risk factors of polypoid lesions of gallbladder (PLG) among the health examinees in the Shanghai region, China. METHODS: A total of 11 816 subjects who underwent health examinati... AIM: To investigate the prevalence and risk factors of polypoid lesions of gallbladder (PLG) among the health examinees in the Shanghai region, China. METHODS: A total of 11 816 subjects who underwent health examinations in our hospital between August 2010 and February 2011 were analyzed retrospectively. Among them, there were 7174 men and 4642 women. PLG was diagnosed by the real-time ultrasonography. Those with the body mass index (BMI) ≥ 28 were considered to be obese. Blood biochemical indices were detected with the fully automatic biochemical analyzer and hepatitis B surface antigen (HBsAg) was tested by the automated enzyme immunoassay. The correlations between the prevalence of PLG and age, sex, BMI, serum cholesterol (T-Cho), triglycerides (TG),blood sugar, HBsAg, high-density lipoprotein (HDL-C), low-density lipoprotein (LDL-C), gallstone and fatty liver were investigated. After univariate analysis of 11 variables, stepwise logistic regression analysis was performed to explore the risk factors of PLG. RESULTS: There was a significant difference in sex, T-Cho, HBsAg, HDL-C, LDL-C and fatty liver between the PLG-positive group and the PLG-negative group (332/163 vs 6842/4479, P = 0.003; 22/473 vs 295/11 026, P =0.013; 92/403 vs 993/10 328, P = 0.001; 47/448 vs 332/10 989, P = 0.001; 32/463 vs 381/10 940, P = 0.001; 83/412 vs 3260/8061, P = 0.001). No significant difference was found in the age, BMI, TG, blood sugar and gallstone between the two groups (47.3 ± 26 vs 45.1 ± 33, P = 0.173; 59/436 vs 1097/10 224, P = 0.102; 52/443 vs 982/10 339, P = 0.158; 17/478 vs 295/11 026, P = 0.26; 24/471 vs 395/10 926, P = 0.109). Logistic regression analysis showed that the sex, HBsAg and HDL-C were independent risk factors for the development of PLG in a descending order of HDL-C > HBsAg > sex. CONCLUSION: In healthy people, the male gender, positive HBsAg, and low HDL-C confer higher risks of PLG development. 展开更多
关键词 POLYPOID GALLBLADDER Risk factors UItraso-nography Health examination
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The Impact of the Numbers of Monitoring Stations on the National and Regional Air Quality Assessment in China During 2013-18 被引量:2
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作者 Hongyan LUO Xiao TANG +8 位作者 Huangjian WU lei kong Qian WU Kai CAO Yating SONG Xuechun LUO Yao WANG Jiang ZHU Zifa WANG 《Advances in Atmospheric Sciences》 SCIE CAS CSCD 2022年第10期1709-1720,共12页
China national air quality monitoring network has become the core data source for air quality assessment and management in China.However,during network construction,the significant change in numbers of monitoring site... China national air quality monitoring network has become the core data source for air quality assessment and management in China.However,during network construction,the significant change in numbers of monitoring sites with time is easily ignored,which brings uncertainty to air quality assessments.This study aims to analyze the impact of change in numbers of stations on national and regional air quality assessments in China during 2013-18.The results indicate that the change in numbers of stations has different impacts on fine particulate matter(PM_(2.5))and ozone concentration assessments.The increasing number of sites makes the estimated national and regional PM_(2.5) concentration slightly lower by 0.6−2.2μg m^(−3) and 1.4−6.0μg m^(−3) respectively from 2013 to 2018.The main reason is that over time,the monitoring network expands from the urban centers to the suburban areas with low population densities and pollutant emissions.For ozone,the increasing number of stations affects the long-term trends of the estimated concentration,especially the national trends,which changed from a slight upward trend to a downward trend in 2014−15.Besides,the impact of the increasing number of sites on ozone assessment exhibits a seasonal difference at the 0.05 significance level in that the added sites make the estimated concentration higher in winter and lower in summer.These results suggest that the change in numbers of monitoring sites is an important uncertainty factor in national and regional air quality assessments,that needs to be considered in long-term concentration assessment,trend analysis,and trend driving force analysis. 展开更多
关键词 monitoring network newly added sites PM_(2.5) OZONE
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基于OTT数据的区块化深度规划方法 被引量:2
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作者 雷空 周程 +1 位作者 包其齐 易小洋 《邮电设计技术》 2019年第7期38-44,共7页
从OTT数据的组成结构、展现方式、关键字段的选取等方面,从深度规划的角度介绍了OTT数据;同时,从场景、需求和历史疑难站等维度,定义了区块化的选择方法,以及OTT数据的分析方法;并从网络弱覆盖、网络价值区域2个方面,描述了综合覆盖深... 从OTT数据的组成结构、展现方式、关键字段的选取等方面,从深度规划的角度介绍了OTT数据;同时,从场景、需求和历史疑难站等维度,定义了区块化的选择方法,以及OTT数据的分析方法;并从网络弱覆盖、网络价值区域2个方面,描述了综合覆盖深度规划的方法及流程,并辅以试点案例分析。此外,从电信企业市场发展、基站维护、Wi-Fi应用以及拓展应用等方面,对OTT数据的应用广度进行了探讨。 展开更多
关键词 OTT 网络 深度规划 应用场景 弱覆盖 价值区域 区块化 综合覆盖
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Real-world emission characteristics of carbonyl compounds from agricultural machines based on a portable emission measurement system 被引量:1
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作者 Wenhan Yu Xianbao Shen +8 位作者 BoboWu lei kong Kaijie Xuan Cheng Zhao Xinyue Cao Xuewei Hao Xin Li Hanyu Zhang Zhiliang Yao 《Journal of Environmental Sciences》 SCIE EI CAS CSCD 2023年第2期846-859,共14页
Emissions of carbonyl compounds from agricultural machines cannot be ignored.Carbonyl compounds can cause the formation of ozone(O3)and secondary organic aerosols,which can cause photochemical smog to form.In this stu... Emissions of carbonyl compounds from agricultural machines cannot be ignored.Carbonyl compounds can cause the formation of ozone(O3)and secondary organic aerosols,which can cause photochemical smog to form.In this study,20 agricultural machines were tested using portable emission measurement system(PEMS)under real-world tillage processes.The exhaust gases were sampled using 2,4-dinitrophenylhydrazine cartridges,and 15 carbonyl compounds were analyzed by high-performance liquid chromatography.Carbonyl compound emission factors for agricultural machines were 51.14–3315.62 mg/(kg-fuel),and were 2.58±2.05,0.86±1.07 and 0.29±0.20 g/(kg-fuel)for China 0,China II and China III emission standards,respectively.Carbonyl compound emission factor for sowing seeds of China 0 agricultural machines was 3.32±1.73 g/(kg-fuel).Formaldehyde,acetaldehyde and acrolein were the dominant carbonyl compounds emitted.Differences in emission standards and tillage processes impact ozone formation potential(OFP).The mean OFP was 20.15±16.15 g O3/(kg-fuel)for the China 0 emission standard.The OFP values decreased by 66.9% from China 0 to China II,and 67.4%from China II to China III.The mean OFP for sowing seeds of China 0 agricultural machines was 25.92±13.84 g O3/(kg-fuel).Between 1.75 and 24.22 times more ozone was found to be formed during sowing seeds than during other processes for China 0 and China II agricultural machines.Total carbonyl compound emissions from agricultural machines in China was 19.23 Gg in 2019.The results improve our understanding of carbonyl compound emissions from agricultural machines in China. 展开更多
关键词 Agricultural machines Carbonyl compounds Emission characteristics Tillage process PEMS
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酚醛/SiO_2双体系凝胶网络结构杂化气凝胶的制备与性能 被引量:10
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作者 师建军 孔磊 +3 位作者 左小彪 刘登瑶 严蛟 冯志海 《高分子学报》 SCIE CAS CSCD 北大核心 2018年第10期1307-1314,共8页
通过Sol-Gel反应过程控制,调节酚醛树脂(PR)溶液和SiO_2溶胶液的凝胶时间,共凝胶反应制备PR和SiO_2凝胶网络互穿的PR/SiO_2杂化气凝胶.考察了杂化气凝胶表观密度、收缩率、孔结构、微观形貌、热稳定性和力学性能随SiO_2气凝胶含量的基... 通过Sol-Gel反应过程控制,调节酚醛树脂(PR)溶液和SiO_2溶胶液的凝胶时间,共凝胶反应制备PR和SiO_2凝胶网络互穿的PR/SiO_2杂化气凝胶.考察了杂化气凝胶表观密度、收缩率、孔结构、微观形貌、热稳定性和力学性能随SiO_2气凝胶含量的基本变化规律.研究结果表明:伴随SiO_2气凝胶含量的增加,PR/SiO_2杂化气凝胶表观密度正比增加;同纯PR有机气凝胶相比,杂化气凝胶孔结构得到明显改善,当[TEOS]=1.50 mol/L时,平均孔径减小了一半,降至0.25μm,比表面积由24.60 m^2/g增至44 m^02/g左右;微观形貌照片显示有机气凝胶网络骨架中的大孔逐渐被SiO_2溶胶粒子填充,变成更细小疏松的孔结构形貌,孔径分布明显变宽,SiO_2气凝胶在PR凝胶骨架中纳米尺度内均匀分散;无机SiO_2气凝胶的引入能有效提高有机气凝胶骨架结构的强度和热稳定性,纳米分散SiO_2溶胶粒子的热阻隔效应抑制了PR有机骨架的热分解速率,当[TEOS]=1.00 mol/L时,杂化气凝胶的T_(max)由539℃提高到602℃,热分解温度区间明显展宽. 展开更多
关键词 气凝胶 共凝胶 杂化 溶胶-凝胶 孔结构
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CGPS:A machine learning-based approach integrating multiple gene set analysis tools for better prioritization of biologically relevant pathways 被引量:11
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作者 Chen Ai lei kong 《Journal of Genetics and Genomics》 SCIE CAS CSCD 2018年第9期489-504,共16页
Gene set enrichment(GSE) analyses play an important role in the interpretation of large-scale transcriptome datasets. Multiple GSE tools can be integrated into a single method as obtaining optimal results is challen... Gene set enrichment(GSE) analyses play an important role in the interpretation of large-scale transcriptome datasets. Multiple GSE tools can be integrated into a single method as obtaining optimal results is challenging due to the plethora of GSE tools and their discrepant performances. Several existing ensemble methods lead to different scores in sorting pathways as integrated results; furthermore, it is difficult for users to choose a single ensemble score to obtain optimal final results. Here, we develop an ensemble method using a machine learning approach called Combined Gene set analysis incorporating Prioritization and Sensitivity(CGPS) that integrates the results provided by nine prominent GSE tools into a single ensemble score(R score) to sort pathways as integrated results. Moreover, to the best of our knowledge, CGPS is the first GSE ensemble method built based on a priori knowledge of pathways and phenotypes. Compared with 10 widely used individual methods and five types of ensemble scores from two ensemble methods, we demonstrate that sorting pathways based on the R score can better prioritize relevant pathways, as established by an evaluation of 120 simulated datasets and 45 real datasets.Additionally, CGPS is applied to expression data involving the drug panobinostat, which is an anticancer treatment against multiple myeloma. The results identify cell processes associated with cancer, such as the p53 signaling pathway(hsa04115); by contrast, according to two ensemble methods(EnrichmentBrowser and EGSEA), this pathway has a rank higher than 20, which may cause users to miss the pathway in their analyses. We show that this method, which is based on a priori knowledge, can capture valuable biological information from numerous types of gene set collections, such as KEGG pathways, GO terms, Reactome, and BioCarta. CGPS is publicly available as a standalone source code at ftp://ftp.cbi.pku.edu.cn/pub/CGPS_download/cgps-1.0.0.tar.gz. 展开更多
关键词 Gene expression Differential expression Gene set enrichment Support vector machine
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Evaluation of the effect of wall boundary conditions on numerical simulations of circulating fluidized beds 被引量:3
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作者 lei kong Chao Zhang Jesse Zhu 《Particuology》 SCIE EI CAS CSCD 2014年第2期114-123,共10页
A computational fluid dynamics (CFD) modeling of the gas-solids two-phase flow in a circulating fluidized bed (CFB) riser is carried out. The Eularian-Eularian method with the kinetic theory of granular flow is us... A computational fluid dynamics (CFD) modeling of the gas-solids two-phase flow in a circulating fluidized bed (CFB) riser is carried out. The Eularian-Eularian method with the kinetic theory of granular flow is used to solve the gas-solids two-phase flow in the CFB riser. The wall boundary condition of the riser is defined based on the Johnson and Jackson wall boundary theory (Johnson & Jackson, 1987) with specularity coefficient and particle-wall restitution coefficient.The numerical results show that these two coefficients in the wall boundary condition play a major role in the predicted solids lateral velocity, which affects the solid particle distribution in the CFB riser. And the effect of each of the two coefficients on the solids distribution also depends on the other one. The generality of the CFD model is further validated under different operatin~ conditions of the CFB riser. 展开更多
关键词 CFD Circulating fluidized bed Gas-solids two-phase flowWall boundary conditionSpecularity coefficientParticle-wall restitution coefficient
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Variation characteristics of fine particulate matter and its components in diesel vehicle emission plumes
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作者 Xianbao Shen Jiateng Hao +8 位作者 lei kong Yue Shi Xinyue Cao Jiacheng Shi Zhiliang Yao Xin Li Bobo Wu Yiming Xu Kebin He 《Journal of Environmental Sciences》 SCIE EI CAS CSCD 2021年第9期138-149,共12页
A rapid reaction occurs near the exhaust nozzle when vehicle emissions contact the air.Twenty diesel vehicles were studied using a new multipoint sampling system that is suitable for studying the exhaust plume near th... A rapid reaction occurs near the exhaust nozzle when vehicle emissions contact the air.Twenty diesel vehicles were studied using a new multipoint sampling system that is suitable for studying the exhaust plume near the exhaust nozzle.The variation characteristics of fine particle matter(PM_(2.5)) and its components in diesel vehicle exhaust plumes were analyzed.The PM_(2.5) emissions gradually increased with increasing distance from the nozzle in the plume.Elemental carbon emissions remained basically unchanged, organic carbon and total carbon(TC) increased with increasing distance.The concentrations of SO_(4)^(2-),NO_(3)^(-) and NH_(4)^(+) (SNA) directly emitted by the vehicles were very low but increased rapidly in the exhaust plume.The selective catalytic reduction(SCR) reduced 42.7% TC, 40% NO_(3)^(-) emissions, but increased 104% SO_(4)^(2-) and 36% NH_(4)^(+) emissions, respectively.In summary,the SCR reduced 29% primary PM_(2.5) emissions for the tested diesel vehicles.The NH_(4)NO_(3) particle formation maybe more important in the plume, and there maybe other forms of formation of NH_(4)^(+) (eg.NH4Cl).The generation of secondary organic carbon(SOC) plays a leading role in the generation of secondary PM_(2.5).The SCR enhanced the formation of SOC and SNA in the plume, but comprehensive analysis shows that the SCR more enhanced the SNA formation in the plume, which is mainly new particles formation process.The inconsistency between secondary organic aerosol(SOA) and primary organic aerosol definitions is one of the important reasons for the difference between SOA simulation and observation. 展开更多
关键词 Variation characteristics Diesel vehicle Emission plume PM2.5 COMPONENTS
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