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Treatment, residual chlorine and season as factors affecting variability of trihalomethanes in small

Roberta DYCK,Geneviève COOL,Manuel RODRIGUEZ,Rehan SADIQ

《环境科学与工程前沿(英文)》 2015年 第9卷 第1期   页码 171-179 doi: 10.1007/s11783-014-0750-1

摘要: Seasonal variability in source water can lead to challenges for drinking water providers related to operational optimization and process control in treatment facilities. The objective of this study is to investigate seasonal variability of water quality in municipal small water systems (<3000 residents) supplied by surface waters. Residual chlorine and trihalomethanes (THM) were measured over seven years (2003–2009). Comparisons are made within each system over time, as well as between systems according to the type of their treatment technologies. THM concentrations are generally higher in the summer and autumn. The seasonal variability was generally more pronounced in systems using chlorination plus additional treatment. Chloroform, total THM (TTHM) and residual chlorine concentrations were generally lower in systems using chlorination plus additional treatment. Conversely, brominated THM concentrations were higher in systems using additional treatment. Residual chlorine was highest in the winter and lowest in the spring and summer. Seasonal variations were most pronounced for residual chlorine in systems with additional treatment. There was generally poor correlation between THM concentrations and concentrations of residual chlorine. Further study with these data will be beneficial in finding determinants and indicators for both quantity and variability of disinfection byproducts and other water quality parameters.

关键词: drinking water     residual chlorine     seasonal variability     small municipal systems     treatment technologies     trihalomethanes    

Unlocked disinfection by-product formation potential upon exposure of swimming pool water to additional stimulants

Alvyn P. Berg, Ting-An Fang, Hao L. Tang

《环境科学与工程前沿(英文)》 2019年 第13卷 第1期 doi: 10.1007/s11783-019-1098-3

摘要:

• Swimming pool water was studied for DBPs upon exposure to additional stimulants.

• DBP formation could be induced by residual chlorine and extended incubation.

• Urine led to a massive formation of chloroform with additional stimulants.

• Reactions between chlorine and anthropogenic organics were slow and long-lasting.

• Urine control and air ventilation should be on the priority list for pool management.

关键词: Trihalomethanes     Haloacetic acids     Chloroform     Residual chlorine     Anthropogenic organics     Swimming pool water    

Concentration levels of disinfection by-products in 14 swimming pools of China

Xiaolu ZHANG,Hongwei YANG,Xiaofeng WANG,Yu ZHAO,Xiaomao WANG,Yuefeng XIE

《环境科学与工程前沿(英文)》 2015年 第9卷 第6期   页码 995-1003 doi: 10.1007/s11783-015-0797-7

摘要: Swimming has become a popular exercising and recreational activity in China but little is known about the disinfection by-products (DBPs) concentration levels in the pools. This study was conducted as a survey of the DBPs in China swimming pools, and to establish the correlations between the DBP concentrations and the pool water quality parameters. A total of 14 public indoor and outdoor pools in Beijing were included in the survey. Results showed that the median concentrations for total trihalomethanes (TTHM), nine haloacetic acids (HAA9), chloral hydrate (CH), four haloacetonitriles (HAN4), 1,1-dichloropropanone, 1,1,1-trichloropropanone and trichloronitromethane were 33.8, 109.1, 30.1, 3.2, 0.3, 0.6 µg?L and below detection limit, respectively. The TTHM and HAA9 levels were in the same magnitude of that in many regions of the world. The levels of CH and nitrogenous DBPs were greatly higher than and were comparable to that in typical drinking water, respectively. Disinfection by chlorine dioxide or trichloroisocyanuric acid could substantially lower the DBP levels. The outdoor pools had higher TTHM and HAA9 levels, but lower trihaloacetic acids (THAA) levels than the indoor pools. The TTHM and HAA9 concentrations could be moderately correlated with the free chlorine and total chlorine residuals but not with the total organic carbon (TOC) contents. When the DBP concentration levels from other survey studies were also included for statistical analysis, a good correlation could be established between the TTHM levels and the TOC concentration. The influence of chlorine residual on DBP levels could also be significant.

关键词: disinfection by-products (DBPs)     swimming pool     correlation     total organic carbon (TOC)     chlorine residual     bather load    

Surface-tailoring chlorine resistant materials and strategies for polyamide thin film composite reverse

《化学科学与工程前沿(英文)》 2022年 第16卷 第5期   页码 564-591 doi: 10.1007/s11705-021-2109-z

摘要: Polyamide thin film composite membranes have dominated current reverse osmosis market on account of their excellent separation performances compared to the integrally skinned counterparts. Despite their very promising separation performance, chlorine-induced degradation resulted from the susceptibility of polyamide toward chlorine attack has been regarded as the Achilles’s heel of polyamide thin film composite. The free chlorine species present during chlorine treatment can impair membrane performance through chlorination and depolymerization of the polyamide selective layer. From material point of view, a chemically stable membrane is crucial for the sustainable application of membrane separation process as it warrants a longer membrane lifespan and reduces the cost involved in membrane replacement. Various strategies, particularly those involved membrane material optimization and surface modifications, have been established to address this issue. This review discusses membrane degradation by free chlorine attack and its correlation with the surface chemistry of polyamide. The advancement in the development of chlorine resistant polyamide thin film composite membranes is reviewed based on the state-of-the-art surface modifications and tailoring approaches which include the in situ and post-fabrication membrane modifications using a broad range of functional materials. The challenges and future directions in this field are also highlighted.

关键词: reverse osmosis     polyamide     thin film composite membranes     chlorine resistance     surface modification    

Enhanced formation of trihalomethane disinfection byproducts from halobenzoquinones under combined UV/chlorine

《环境科学与工程前沿(英文)》 2022年 第16卷 第6期 doi: 10.1007/s11783-021-1510-7

摘要:

• 2,6-DCBQ and TCBQ generated THMs differently in chlorine and UV/chlorine processes.

关键词: Halobenzoquinone     Trihalomethane     Chlorine disinfection     UV irradiation     Disinfection byproducts     Combined UV/chlorine    

Change in genotoxicity of wastewater during chlorine dioxide and chlorine disinfections and the influence

WANG Lisha, HU Hongying, WANG Chao, Koichi Fujie

《环境科学与工程前沿(英文)》 2007年 第1卷 第1期   页码 18-22 doi: 10.1007/s11783-007-0003-7

摘要: The effects of chlorine dioxide and chlorine disinfections on the genotoxicity of different biologically treated sewage wastewater samples were studied by umu-test. The experiment results showed that when chlorine dioxide dosage was increased from 0 to 30 mg/L, the genotoxicity of wastewater first decreased rapidly and then tended to be stable, while when the chlorine dosage was increased from 0 to 30 mg/L, the genotoxicity of wastewater changed diver sely for different samples. It was then found that ammonia nitrogen did not affect the change of genotoxicity during chlorine dioxide disinfection of wastewater, while it greatly affected the change of genotoxicity during chlorine disin fection of wastewater. When the concentration of ammonia nitrogen was low (< 10 20 mg/L), the genotoxicity of wastewater decreased after chlorine disinfection, and when the concentration of ammonia nitrogen was high (> 10 20 mg/L), the genotoxicity of wastewater increased after chlorine disinfection.

Modeling and verifying chlorine decay and chloroacetic acid formation in drinking water chlorination

Wenjun LIU, Shaoying QI,

《环境科学与工程前沿(英文)》 2010年 第4卷 第1期   页码 65-72 doi: 10.1007/s11783-010-0010-y

摘要: This study presents a phenomenological model that can be used by the water professionals to quantify chlorine decay and disinfection byproduct (DBP) formation in water. The kinetic model was developed by introducing the concept of limiting chlorine demand and extending an established reactive species approach. The limiting chlorine demand, which quantifies chlorine reactive natural organic matter (NOM) on an equivalent basis, was mathematically defined by the relation between ultimate chlorine residue and initial chlorine dose. It was found experimentally that NOM in water has limiting chlorine demand that increases with chlorine dose once the ultimate residue is established. These results indicated that the complex NOM has a unique ability to adjust chemically to the change in redox condition caused by the free chlorine. It is attributed mainly to the redundant functional groups that persist in heterogeneous NOM molecules. The results also demonstrated that the effect of chlorine dose on the rate of chlorine decay can be quantitatively interpreted with the limiting chlorine demand. The kinetic model developed was validated for chlorine decay and chloroacetic acid formation in finished drinking water.

关键词: chlorine demand     chlorine decay     chloroacetic acids     disinfection byproducts     model    

植物氯素营养与含氯化肥科学施用

毛知耘,周则芳,石孝均,刘洪斌

《中国工程科学》 2000年 第2卷 第6期   页码 64-66

摘要:

文章主要概述了植物的氯素营养及科学施用含氯化肥三准则。

关键词: 植物氯营养     耐氯力类型     含氯化肥    

Self-healing polyamide reverse osmosis membranes with temperature-responsive intelligent nanocontainers for chlorine

《化学科学与工程前沿(英文)》 2023年 第17卷 第9期   页码 1183-1195 doi: 10.1007/s11705-022-2287-3

摘要: Improving the performance of reverse osmosis membranes remains great challenge to ensure excellent NaCl rejection while maintaining high water permeability and chlorine resistance. Herein, temperature-responsive intelligent nanocontainers are designed and constructed to improve water permeability and chlorine resistance of polyamide membranes. The nanocontainer is synthesized by layer-by-layer self-assembly with silver nanoparticles as the core, sodium alginate and chitosan as the repair materials, and polyvinyl alcohol as the shell. When the polyamide layer is damaged by chlorine attack, the polyvinyl alcohol shell layer dissolves under temperature stimulation of 37 °C, releasing inner sodium alginate and chitosan to repair broken amide bonds. The polyvinyl alcohol shell responds to temperature in line with actual operating environment, which can effectively synchronize the chlorination of membranes with temperature response and release inner materials to achieve self-healing properties. With adding temperature-responsive intelligent nanocontainers, the NaCl rejection of thin film composite membrane decreased by 15.64%, while that of thin film nanocomposite membrane decreased by only 8.35% after 9 chlorination cycles. Effective repair treatment and outstanding chlorine resistance as well as satisfactory stability suggest that temperature-responsive intelligent nanocontainer has great potential as membrane-doping material for the targeted repair of polyamide reverse osmosis membranes.

关键词: reverse osmosis     nanocontainer     self-healing     chlorine resistance     water permeability    

Secondary transfer length and residual prestress of fractured strand in post-tensioned concrete beams

Lizhao DAI; Wengang XU; Lei WANG; Shanchang YI; Wen CHEN

《结构与土木工程前沿(英文)》 2022年 第16卷 第3期   页码 388-400 doi: 10.1007/s11709-022-0809-1

摘要: An experimental study is performed on five post-tensioned concrete beams to explore the effects of different fracture positions on secondary transfer length and residual prestress of fractured strand. A numerical model is developed and used to predict the secondary transfer length and residual prestress of fractured strand in post-tensioned concrete beams. The model change interaction, which can deactivate and reactivate the elements for simulating the removal and reproduction of parts of the model, is used to reproduce the secondary anchorage of fractured strand. The numerical model is verified by experimental results. Results shows that the fractured strand can be re-anchored in concrete through the secondary anchorage, and the secondary transfer length of fractured strand with the diameter of 15.2 mm is 1133 mm. The residual prestress of fractured strand increases gradually in the secondary transfer length, and tends to be a constant beyond it. When the fractured strand is fully anchored in concrete, a minor prestress loss will appear, and the average prestress loss is 2.28% in the present study.

关键词: post-tensioned concrete beams     strand fracture     secondary transfer length     residual prestress    

Minimal residual disease in solid tumors: an overview

《医学前沿(英文)》 2023年 第17卷 第4期   页码 649-674 doi: 10.1007/s11684-023-1018-6

摘要: Minimal residual disease (MRD) is termed as the small numbers of remnant tumor cells in a subset of patients with tumors. Liquid biopsy is increasingly used for the detection of MRD, illustrating the potential of MRD detection to provide more accurate management for cancer patients. As new techniques and algorithms have enhanced the performance of MRD detection, the approach is becoming more widely and routinely used to predict the prognosis and monitor the relapse of cancer patients. In fact, MRD detection has been shown to achieve better performance than imaging methods. On this basis, rigorous investigation of MRD detection as an integral method for guiding clinical treatment has made important advances. This review summarizes the development of MRD biomarkers, techniques, and strategies for the detection of cancer, and emphasizes the application of MRD detection in solid tumors, particularly for the guidance of clinical treatment.

关键词: MRD     solid tumor     CTC     ctDNA    

Characterization of chlorine and heavy metals for the potential recycling of bottom ash from municipal

Boran WU, Dongyang WANG, Xiaoli CHAI, Fumitake TAKAHASHI, Takayuki SHIMAOKA

《环境科学与工程前沿(英文)》 2016年 第10卷 第4期 doi: 10.1007/s11783-016-0847-9

摘要: Industrial waste mixed with MSW is the main source of heavy metal in bottom ash. Chlorine content in bottom ash is controlled both by plastic and kitchen waste. Insoluble chlorine in Chinese MSWI bottom ash exists primarily as AlOCl. Bottom ash is an inevitable by-product from municipal solid waste (MSW) incineration plants. Recycling it as additives for cement production is a promising disposal method. However, the heavy metals and chlorine are the main limiting factors because of the potential environmental risks and corrosion of cement kilns. Therefore, investigating heavy metal and chlorine characteristics of bottom ash is the significant prerequisite of its reuse in cement industries. In this study, a correlative analysis was conducted to evaluate the effect of the MSW components and collection mode on the heavy metal and chlorine characteristics in bottom ash. The chemical speciation of insoluble chlorine was also investigated by synchrotron X-ray diffraction analysis. The results showed that industrial waste was the main source of heavy metals, especially Cr and Pb, in bottom ash. The higher contents of plastics and kitchen waste lead to the higher chlorine level (0.6 wt.%–0.7 wt.%) of the bottom ash. The insoluble chlorine in the MSW incineration bottom ash existed primarily as AlOCl, which was produced under the high temperature (1250℃) in incinerators.

关键词: Bottom ash     Chlorine     Heavy metals     Waste inputs     Synchrotron X-ray diffraction     AlOCl    

Effect of the ultraviolet/chlorine process on microbial community structure, typical pathogens, and antibiotic

《环境科学与工程前沿(英文)》 2022年 第16卷 第8期 doi: 10.1007/s11783-022-1521-z

摘要:

• UV/chlorine can effectively remove VBNC pathogens, ARGs and MGEs in reclaimed water.

关键词: UV/chlorine process     Pathogen     Antibiotic resistance genes     High-throughput qPCR     Reclaimed water    

Characterization of chlorine dioxide as disinfectant for the removal of low concentration microcystins

Mingsong WU, Junli HUANG, Yuling ZHANG, Shijie YOU, Shaofeng LI, Zhilin RAN, Yu TIAN

《环境科学与工程前沿(英文)》 2012年 第6卷 第1期   页码 75-81 doi: 10.1007/s11783-011-0331-5

摘要: Microcystins, which represents one kind of cancerogenic organic compounds, is abundant in eutrophication water. The effects of reaction factors on chlorine dioxide (ClO ) for removal of low-concentration Microcystin-LR, Microcystin-RR, and Microcystin-YR in water as well as the reaction mechanisms was investigated by using enzyme-linked immunosorbent assay (ELISA) kit and gas chromatography–mass spectrometry (GC-MS). The results showed that MC-LR, MC-RR, and MC-YR could be efficiently decomposed by ClO . The degradation efficiency was shown positively correlated to the concentration of ClO and reaction time; while the effect of reaction temperature and pH is slight. The kinetic constants and activation energies of the reaction of MC-LR, MC-RR, and MC-YR with ClO are determined as 459.89, 583.15, 488.43 L·(mol·min) and 64.78, 53.01, 59.15 kJ·mol , respectively. As indicated by high performance liquid chromatography mass spectrometer (HPLC-MS) analysis, degradation should be accomplished via destruction of Adda group by oxidation, with the formation of dihydroxy substituendums as end products. This study has provided a fundamental demonstration of ClO serving as oxidizing disinfectant to eliminate microcystins from raw water source.

关键词: disinfection     chlorine dioxide     microcystins     reaction mechanism    

The formation mechanism and the influence factor of residual stress in machining

null

《机械工程前沿(英文)》 2014年 第9卷 第3期   页码 265-269 doi: 10.1007/s11465-014-0311-0

摘要:

Residual stresses generated in cutting process have important influences on workpiece performance. The paper presents a method of theoretical analysis in order to explicate the formation mechanism of residual stresses in cutting. An important conclusion is drawn that the accumulated plastic strain is the main factor which determines the nature and the magnitude of surface residual stresses in the workpiece. On the basis of the analytical model for residual stress, a series of simulations for residual stress prediction during cutting AISI 1045 steel are implemented in order to obtain the influences of cutting speed, depth of cut and tool edge radius on surface residual stress in the workpiece. And these influences are explained from the perspective of formation mechanism of residual stress in cutting. The conclusions have good applicability and can be used to guide the parameters selection in actual production.

关键词: residual stress     analytical model     strain     plastic     cutting parameter    

标题 作者 时间 类型 操作

Treatment, residual chlorine and season as factors affecting variability of trihalomethanes in small

Roberta DYCK,Geneviève COOL,Manuel RODRIGUEZ,Rehan SADIQ

期刊论文

Unlocked disinfection by-product formation potential upon exposure of swimming pool water to additional stimulants

Alvyn P. Berg, Ting-An Fang, Hao L. Tang

期刊论文

Concentration levels of disinfection by-products in 14 swimming pools of China

Xiaolu ZHANG,Hongwei YANG,Xiaofeng WANG,Yu ZHAO,Xiaomao WANG,Yuefeng XIE

期刊论文

Surface-tailoring chlorine resistant materials and strategies for polyamide thin film composite reverse

期刊论文

Enhanced formation of trihalomethane disinfection byproducts from halobenzoquinones under combined UV/chlorine

期刊论文

Change in genotoxicity of wastewater during chlorine dioxide and chlorine disinfections and the influence

WANG Lisha, HU Hongying, WANG Chao, Koichi Fujie

期刊论文

Modeling and verifying chlorine decay and chloroacetic acid formation in drinking water chlorination

Wenjun LIU, Shaoying QI,

期刊论文

植物氯素营养与含氯化肥科学施用

毛知耘,周则芳,石孝均,刘洪斌

期刊论文

Self-healing polyamide reverse osmosis membranes with temperature-responsive intelligent nanocontainers for chlorine

期刊论文

Secondary transfer length and residual prestress of fractured strand in post-tensioned concrete beams

Lizhao DAI; Wengang XU; Lei WANG; Shanchang YI; Wen CHEN

期刊论文

Minimal residual disease in solid tumors: an overview

期刊论文

Characterization of chlorine and heavy metals for the potential recycling of bottom ash from municipal

Boran WU, Dongyang WANG, Xiaoli CHAI, Fumitake TAKAHASHI, Takayuki SHIMAOKA

期刊论文

Effect of the ultraviolet/chlorine process on microbial community structure, typical pathogens, and antibiotic

期刊论文

Characterization of chlorine dioxide as disinfectant for the removal of low concentration microcystins

Mingsong WU, Junli HUANG, Yuling ZHANG, Shijie YOU, Shaofeng LI, Zhilin RAN, Yu TIAN

期刊论文

The formation mechanism and the influence factor of residual stress in machining

null

期刊论文