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831.
研究配筋圆钢管混凝土轴压短柱火灾后剩余承载力。利用ABAQUS有限元分析软件建立了ISO-834标准升温曲线升温作用下配筋圆钢管混凝土短柱温度场模型,基于温度场分析结果建立了配筋圆钢管混凝土轴压短柱力学分析模型,利用以往试验结果对模型进行了验证,计算结果与实验结果吻合良好。在此基础上进行了火灾后配筋圆钢管混凝土轴压短柱剩余承载力参数分析,选用的参数包括:升温时间、混凝土强度、钢管强度、钢筋强度、含钢率、配筋率、构件截面尺寸等。研究结果表明:在本次参数范围内,在其它条件相同的情况下,与常温下的承载力相比,受火时间越长,截面尺寸越小,构件火灾后剩余承载力的损失越高。结果可供有关钢管混凝土工程火灾后修复加固参考。 相似文献
832.
为明确驾驶人在不同复杂度的交通环境下视觉分心程度对跟车运动状态的影响,在驾驶模拟器上搭建城市、乡村和高速道路3种交通环境,利用视线遮挡方法,设置O、1和2s等3种固定时长,量化被试视觉分心程度;对26位被试进行模拟器驾驶试验,采集车辆速度、纵向加速度和车辆位置等参数;采用重复测量一般线性模型,分析视觉分心程度对上述参数... 相似文献
833.
Yanqing Zhou Yili Wang Shuoxun Dong Haotian Hao Junyi Li Chenyang Liu Xiaolin Li Yao Tong 《环境科学学报(英文版)》2022,34(3):26-39
Cationic hydrogels have receive d great attention to control eutrophication and recycle phosphate.In this study,a type of La(OH)3 loaded magnetic MAPTAC-based cationic hydrogel(La(OH)3@MMCH) was developed as a potential adsorbent for enhanced phosphate removal from aqueous environment.La(OH)3@MMCH exhibited high adsorption capacity of105.72±5.99 mg P/g,and reached equilibrium within 2 hr.La(OH)3@MMCH could perform effectively in a wide pH range from 3.... 相似文献
834.
为了定量生态相关物种基因组中低丰度的5-甲基-2-脱氧胞苷(5-mdC),建立了一种采用高效液相色谱串联质谱(HPLC-MS/MS)的无标记方法.全基因组DNA甲基化计算公式5-mdC (mole)/(5-mdC (mole)+dC (mole)可以转化为1/(1+dC (mole)/5-mdC (mole)),然后通过HPLC-MS/MS得到DNA样品中5-mdC和dC的物质的量比(dC (mole)/5-mdC (mole))即可得到基因组DNA甲基化值.此外,还对HPLC条件进行了优化使正常核苷和修饰核苷基线分离,消除分析物的交叉干扰.本方法避免了使用昂贵的稳定同位素标记内标,在等度高效液相色谱条件下实现了正常和修饰核苷基线分离,5-mdC和dC的保留时间分别为5.50和3.06min.5-mdC和dC的定量限分别为14.2和19.1pg/mL.日内和日间偏差和准确性(相对误差)都≤ 10%.该方法测定的小牛胸腺DNA和大型蚤及秀丽线虫的全基因组DNA甲基化值分别为(6.44 ±0.25)%,(0.097 ±0.010)%和(0.025 ±0.002)%.采用HPLC-MS/MS技术建立并验证了一种快速、高精密度和灵敏度的DNA样品全基因组DNA甲基化测定方法,适用于评估环境污染物对生态学相关物种的潜在表观遗传风险. 相似文献
835.
采用珠三角常规空气污染物与成分监测数据,通过分析对比2020年不同阶段的污染物浓度与气象等数据,研究了2020年珠三角臭氧污染特征与其主要成因。结果表明,2020年各月珠三角超标天首要污染物是O3,珠三角2020年O3评价浓度为148μg/m3,同比下降16%,AQI达标率同比上升9.5%。2020年O3污染相对严重的月份是4、8~11月,对应的月度O3评价浓度分别达到175,164,166,171,162μg/m3,均超过国家二级标准;其它月份均达标,6~12月O3污染情况同比改善明显,O3污染减轻使AQI达标率同比上升明显。2020年一季度受春节假期和疫情因素等共同影响,大气污染物排放量明显减少,但O3浓度下降不明显,主要由于日照时数同比上升约19%;4月全面复工复产,以及辐射相对较强的气象条件,使O3评价浓度同比上升约58%;5~8月“百日服务”与9~12月“百日行动”采取的污染防治措施有效降低O3前体物排放量,NO2浓度同比下降了22%~23%,VOCs浓度下降了18%~26%,使2个阶段的O3评价浓度均同比下降了20%左右。 相似文献
836.
Lu Zhao Evans Atoni Raphael Nyaruaba Yao Du Huaiyu Zhang Oscar Donde Doudou Huang Shuqi Xiao Nanjie Ren Teng Ma Zhu Shu Zhiming Yuan Lei Tong Han Xia 《环境科学学报(英文版)》2022,34(2):115-120
Wastewater-based epidemiology(WBE) has emerged as an effective environmental surveillance tool in monitoring fecal-oral pathogen infections within a community. Congruently, SARS-Co V-2, the etiologic agent of COVID-19, has been demonstrated to infect the gastrointestinal tissues, and be shed in feces. In the present study, SARS-Co V-2 RNA was concentrated from wastewater, sludge, surface water, ground water, sediment, and soil samples of municipal and hospital wastewater systems and related envi... 相似文献
837.
Fangjie Li Shengrui Tong Chenhui Ji Xinran Zhang Deng Lin Wenqian Zhang Weiran Li Lili Wang Maofa Ge Lixin Xia 《环境科学学报(英文版)》2022,34(4):85-97
The field observation of 54 non-methane hydrocarbon compounds (NMHCs) was conducted from September 1 to October 20 in 2020 during autumn in Haidian District, Beijing. The mean concentration of total NMHCs was 29.81 ± 11.39 ppbv during this period, and alkanes were the major components. There were typical festival effects of NMHCs with lower concentration during the National Day. Alkenes and aromatics were the dominant groups in ozone formation potential (OFP) and OH radical loss rate (LOH). The positive matrix factorization (PMF) running results revealed that vehicular exhaust became the biggest source in urban areas, followed by liquefied petroleum gas (LPG) usage, solvent usage, and fuel evaporation. The box model coupled with master chemical mechanism (MCM) was applied to study the impacts of different NMHCs sources on ozone (O3) formation in an O3 episode. The simulation results indicated that reducing NMHCs concentration could effectively suppress O3 formation. Moreover, reducing traffic-related emissions of NMHCs was an effective way to control O3 pollution at an urban site in Beijing. 相似文献
838.
Cobalt iron spinel (CoFe2O4) has been considered as a good heterogeneous catalysis to peroxymonosulfate (PMS) in the degradation of persistent organic pollutants due to its magnetic properties and good chemical stability. However, its catalytic activity needs to be further improved. Here, a facial strategy, “in-situ substitution”, was adopted to modify CoFe2O4 to improve its catalytic performance just by suitably increasing the Co/Fe ratio in synthesis process. Compared with CoFe2O4, the newly synthesized Co1.5Fe1.5O4, could not only significantly improve the degradation efficiency of phenol, from 50.69 to 93.6%, but also exhibited more effective mineralization ability and higher PMS utilization. The activation energy advantage for phenol degradation using Co1.5Fe1.5O4 was only 44.2 kJ/mol, much lower than that with CoFe2O4 (127.3 kJ/mol). A series of related representations of CoFe2O4 and Co1.5Fe1.5O4 were compared to explore the possible reasons for the outstanding catalytic activity of Co1.5Fe1.5O4. Results showed that Co1.5Fe1.5O4 as well represented spinel crystal as CoFe2O4 and the excess cobalt just partially replaced the position of iron without changing the original structure. Co1.5Fe1.5O4 had smaller particle size (8.7 nm), larger specific surface area (126.3 m2/g), which was more favorable for exposure of active sites. Apart from the superior physical properties, more importantly, more reactive centers Co (Ⅱ) and surface hydroxyl compounds generated on Co1.5Fe1.5O4, which might be the major reason. Furthermore, Co1.5Fe1.5O4 behaved good paramagnetism, wide range of pH suitability and strong resistance to salt interference, making it a new prospect in environmental application. 相似文献
839.
840.
以MIL-88A (Fe)为载体,通过原位沉淀法和离子交换法成功合成双Z型三元复合材料MIL-88A (Fe)/Ag3PO4/AgI (MAI),并将其应用于光芬顿体系中,高效去除染料废水中的罗丹明B (RhB).棒状的MIL-88A (Fe)作为载体,减少了Ag3PO4和AgI颗粒的团聚现象,形成的双Z型异质结减少了电子-空穴对的复合,提高了光催化活性.在催化剂为0.5g/L,初始pH值为3.0,H2O2浓度0.4mmol/L的条件下,20min内100mL的20mg/L的RhB可被完全降解,并且在循环5次使用后仍保持较高的催化性能.此外,自由基捕获实验和电子自旋共振实验表明h+,O2·﹣和HO·是MAI/Vis/H2O2催化体系中的主要活性物质.最后,提出了MAI降解的可能机理. 相似文献