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The impact of preozonation on the coagulation of cellular organic matter produced by Microcystis aeruginosa and its toxin degradation

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Journal of Environmental Sciences 2020年第12期32卷 124-133页

作者： Magdalena Barešová Jana Naceradská Katerina Novotná LenkaCermáková Martin Pivokonský Institute of Hydrodynamics of the Czech Academy of Sciences Pod Patankou 516612 Prague 6Czech Republic

Ozonation pretreatment is typically implemented to improve algal cell coagulation. However, knowledge on the effect of ozonation on the characteristics and coagulation of associated algal organic matter, particularly cellular organic matter(COM), which is extensively released during algal bloom decay, is limited. Hence, this study aimed to elucidate the impact of ozonation applied before the coagulation of dissolved COM from the cyanobacteria Microcystis aeruginosa. Additionally, the degradation of microcystins(MCs) naturally present in the COM matrix was investigated. A range of ozone doses(0.1–1.0 mg O3/mg of dissolved organic carbon – DOC) and ozonation pH values(pH 5, 7 and 9) were tested, while aluminium and ferric sulphate coagulants were used for subsequent coagulation. Despite negligible COM removal, ozonation itself eliminated MCs, and a lower ozone dose was required when performing ozonation at acidic or neutral pH(0.4 mg O3/mg DOC at pH 5 and 7 compared to 0.8 mg O3/mg DOC at pH 9). Enhanced MC degradation and a similar pattern of pH dependence were observed after preozonation-coagulation, whereas coagulation alone did not sufficiently remove MCs. In contrast to the benefits of MC depletion, preozonation using ≥0.4 mg O3/mg DOC decreased the coagulation efficiency(from 42%/48% to 28%–38%/41%–44% using Al/Fe-based coagulants), which was more severe with increasing ozone dosage. Coagulation was also influenced by the preozonation pH, where pH 9 caused the lowest reduction in COM removal. The results indicate that ozonation efficiently removes MCs, but its employment before COM coagulation is disputable due to the deterioration of coagulation.

关键词： Algal organic matter Coagulation Microcystins Microcystis aeruginosa Ozonation

Elucidating the dynamics of polymer transport through nanopores using asymmetric salt concentrations

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Nano Research 2022年第11期15卷 9943-9953页

作者： Martin Charron Lucas Philipp Liqun He Vincent Tabard-Cossa Department of Physics University of OttawaOttawaON K1N 6N5Canada

While notable progress has been made in recent years both experimentally and theoretically in understanding the highly complex dynamics of polymer capture and transport through nanopores,there remains significant disagreement between experimental observation and theoretical prediction that needs to be *** salt concentrations,where the concentrations of ions on each side of the membrane are different,can be used to enhance capture rates and prolong translocation times of electrophoretically driven polymers translocating through a nanopore from the low salt concentration reservoir,which are both attractive features for single-molecule ***,since asymmetric salt concentrations affect the electrophoretic pull inside and outside the pore differently,it also offers a useful control parameter to elucidate the otherwise inseparable physics of the capture and translocation *** this work,we attempt to paint a complete picture of the dynamics of polymer capture and translocation in both symmetric and asymmetric salt concentration conditions by reporting the dependence of multiple translocation metrics on voltage,polymer length,and salt concentration *** asymmetric salt concentration conditions,we experimentally observe the predictions of tension propagation theory,and infer the significant impact of the electric field outside the pore in capturing polymers and in altering polymer conformations prior to translocation.

关键词： nanopore DNA translocation salt gradient tension propagation polymer transport

Impact of Shaft Stiffness on Inertial Response of Fixed Speed Wind Turbines

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电力系统自动化 2012年第8期36卷 191-197页

作者： Francisco GONZLEZ-LONGATT Faculty of Engineering and Computing Coventry UniversityCoventry CV1 5FBUnited Kingdom

Future power system faces several challenges,one of them is the high penetration level of intermittent wind power generation,providing small or even no inertial response and being not contributing to the frequency *** effect of shaft stiffness on inertial response of fixed speed wind turbines is *** different drive-train models based on the multi-body system are *** small-signal analysis demonstrates no significant differences between models in terms of electro-mechanical eigen-values for increasing shaft *** natural resonance frequency of drive-train torsion modes shows slightly different values between damped and undamped models,but no significant differences are found in the number-mass ***-domain simulations show the changes in the active power contribution of a wind farm based on a fixed speed wind turbine during the system frequency *** changes in the kinetic energy during the dynamic process are calculated and their contribution to the inertia constant is small and *** largest contribution of the kinetic energy is provided at the beginning of the system frequency disturbance to reduce the rate of the frequency change,it is positive for the frequency stability.

关键词：风力发电机刚度模型惯性风力涡轮机频率稳定性轴定速传动系统

Spinal cord compression secondary to bone metastases from hepatocellular carcinoma

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World Journal of Gastroenterology 2006年第32期12卷 5247-5252页

作者： Dinesh Chandra Doval Komal Bhatia Ashok Kumar Vaid Keechelat Pavithran Jai Bhagwan Sharma Digant Hazarika Amarnath Jena Department of Medical Oncology Rajiv Gandhi Cancer Institute and Research Centre Rohini Sector- 5Delhi-110085India Department of Pathology Rajiv Gandhi Cancer Institute and Research Centre Rohini Sector- 5Delhi-110085India Department of Nuclear Medicine Rajiv Gandhi Cancer Institute and Research Centre Rohini Sector- 5Delhi-110085India

Bone metastases are rare in primary hepatocellular carcinoma （HCC）. Spinal cord compression （SCC） due to bone metastases occur commonly in patients with lung and breast carcinomas, and metastatic HCC is an unusual cause of SCC. Spinal cord compression is an oncologic emergency and treatment delays can lead to irreversible consequences. Thus, the awareness that SCC could be a potential complication of bone metastases due to HCC is of significance in initiation of early treatment that can improve the quality of life and survival of the patients, if diagnosed earlier. This paper describes four cases of primary HCC with varied manifestations of SCC due to bone metastases. The first patient presented primarily with the symptoms of bone pains corresponding to the bone metastases sites rather than symptoms of associated hepatic pathology and eventually developed SCC. The second patient, diagnosed as having HCC, developed extradural SCC leading to paraplegia during the course of illness, for which he underwent emergency laminectomy with posterior fixation. The third patient developed SCC soon after the primary diagnosis and had to undergo emergency laminectomy. Post laminectomy he had good neurological recovery. The Fourth patient presented primarily with radicular pains rather than frank paraplegia as the first manifestation of SCC.

关键词： Alpha feto protein External beam radiotherapy Hepatocellular carcinoma Laminectomy Spinal cord compression

Challenges and countermeasures of urban water systems against climate change:a perspective from China

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Frontiers of Environmental Science & Engineering 2023年第12期17卷 189-195页

作者： Yisheng Shao Yijian Xu China Academy of Urban Planning&Design No.5 Chegongzhuang West RoadBeijing 100044China

Urban water systems are facing various challenges against climate change,impacting cities’security and their sustainable ***,there are three major challenges:submersion risk of coastal cities as glaciers melt and sea level rises,more and severe urban flooding caused by extreme weather like intensified storm surge and heavy precipitation,and regional water resource patterns challenged by alteration of spatial distribution of *** this,two strategies including proactive adaptation and positive mitigation were proposed in this article to realize the reconstruction and optimization of urban water systems,to enhance their resilience,and eventually increase their adaptability and coping ability to climate *** proactive adaptation strategy consists of 1)construction of sponge cities to accommodate the increased regular rainfall and to balance the alterations of spatial redistribution of precipitation;2)reconstruction of excess stormwater discharge and detention system to increase capability for extreme precipitation events based on flood risk assessment under future climate change;3)deployment of forward-looking,ecological,and integrated measures to improve coastal protection capability against inundation risks caused by climate change and sea level *** positive mitigation strategy is to employ the systematic concept in planning and design and to adopt advanced applicable energy-saving technologies,processes,and management practices,aiming at reduction in flux of urban water systems,reinforcement in energy conservation and carbon reduction in both water supply systems and wastewater treatment systems,and thus a reduction of greenhouse gas emission from urban water systems.

关键词： Climate change Urban water system Resilience Adaptation Mitigation

Progress in twin roll casting of magnesium alloys: A review

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Journal of Magnesium and Alloys 2021年第2期9卷 362-391页

作者： Amjad Javaid Frank Czerwinski CanmetMATERIALS Natural Resources CanadaHamiltonOntarioL8P 0A5Canada

Twin roll casting was commercialized for a strip production from ferrous and non-ferrous alloys in the 1950 s;however,its application to magnesium has proven difficult and still creates major *** report describes global efforts in expanding manufacturing capabilities of magnesium sheet through twin roll casting path,offering many benefits,including a reduction in number of processing steps and energy *** addition to hardware design,alloy transformation during processing,product microstructure and properties,examples of successful solutions along with present technology and knowledge limitations are discussed.A particular attention is paid to developments at Canmet MATERIALS,having the only in North America pilot scale twin roll casting facility,devoted to *** are described that aim at design of new magnesium alloys,which could take advantage of unique processing conditions during twin roll casting and contribute to the overall progress in magnesium sheet manufacturing.

关键词： Twin roll casting Magnesium alloys Solidification Magnesium sheet

A review of microfluidic approaches for investigating cancer extravasation during metastasis

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Microsystems & Nanoengineering 2018年第1期4卷 400-412页

作者： Yu-Heng Vivian Ma Kevin Middleton Lidan You Yu Sun Institute of Biomaterials and Biomedical Engineering University of Toronto164 College StreetRoom 407TorontoON M5S 3G9Canada Department of Mechanical and Industrial Engineering University of Toronto5 King’s College RoadRoom 105TorontoON M5S 3G8Canada

Metastases,or migration of cancers,are common and severe cancer *** the 5-year survival rates of primary tumors have greatly improved,those of metastasis remain below 30%,highlighting the importance of investigating specific mechanisms and therapeutic approaches for *** devices have emerged as a powerful platform for drug target identification and drug response screening and allow incorporation of complex interactions in the metastatic microenvironment as well as manipulation of individual *** this work,we review microfluidic devices that have been developed to study cancer cell migration and extravasation in response to mechanical(section‘Microfluidic investigation of mechanical factors in cancer cell migration’),biochemical(section‘Microfluidic investigation of biochemical signals in cancer cell invasion’),and cellular(section‘Microfluidic metastasis-on-a-chip models for investigation of cancer extravasation’)*** highlight the device characteristics,discuss the discoveries enabled by these devices,and offer perspectives on future directions for microfluidic investigations of cancer metastasis,with the ultimate aim of identifying the essential factors for a‘metastasis-on-a-chip’platform to pursue more efficacious treatment approaches for cancer metastasis.

关键词： biochemical signal cancer cell migration cancer cell extravasation metastasis-on-a-chip cellular signal microfluidic mechanical signal

The influence of airtightness on contaminant spread in MURBs in cold climates

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Building Simulation 2022年第2期15卷 249-264页

作者： Philip Mckeen Zaiyi Liao Department of Architectural Science Ryerson UniversityTorontoM5B2K3Canada

Tall buildings in cold climates have unique challenges in maintaining indoor air quality due to stack *** the heating season,interior air buoyancy creates large pressure differentials in vertical shafts that can drive airflow from lower floors into upper *** pressure differential can result in the spread of contaminants throughout a *** recently,concern over COVID-19 has increased attention to the potential spread of airborne diseases in densely populated *** many multi-unit residential buildings,suite ventilation has traditionally relied upon fresh air supplied through a mechanically pressurized *** cold climates,large pressure differentials created by stack-effect can reduce the effectiveness of this *** and CFD simulations are employed to analyze airflow and contaminant spread due to stack *** are conducted on an idealized model of a 10-storey building using a range of experimentally derived airtightness *** demonstrate stack effect can reduce corridor ventilation to suites and even reverse the airflow for leakier *** airflow to suites can result in the accumulation of *** of the airflow can allow contaminants from a suite to spread throughout the *** spread is illustrated as a function of mechanical ventilation,building airtightness,and ambient *** to reduce the influence of stack effect on mechanically pressurized corridors are discussed.

关键词： MURBs ventilation contamination spread stack effect

Removal of organic matter and disinfection by-products precursors in a hybrid process combining ozonation with ceramic membrane ultrafiltration

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Frontiers of Environmental Science & Engineering 2015年第1期9卷 112-120页

作者： Xiaojiang FAN Yi TAO Dequan WEI Xihui ZHANG Ying LEI Hiroshi NOGUCHI Research Center for Environmental Engineering & Management Graduate School at Shenzhen Tsinghua University Shenzhen 518055 China Meidensha Corporation Meiko Building 5-5-50saki Shinagawa-ku Tokyo 141-8616 Japan

The performance of an integrated process including coagulation, ozonation, ceramic ultrafiltration （UF） and biologic activated carbon （BAC） filtration was investigated for the removal of organic matter and disinfection by-products （DBPs） precursors from micropolluted surface water. A pilot scale plant with the capacity of 120 m3 per day was set up and operated for the treatment of drinking water. Ceramic membranes were used with the filtration area of 50 m2 and a pore size of 60 nm. Dissolved organic matter was divided into five fractions including hydrophobic acid （HoA）, base （HOB） and neutral （HoN）, weakly hydrophobic acid （WHOA） and hydrophilic matter （HIM） by DAX-8 and XAD-4 resins. The experiment results showed that the removal of organic matter was significantly improved with ozonation in advance. In sum, the integrated process removed 73% of dissolved organic carbon （DOC）, 87% of UV254, 77% of trihalomethane （THMs） precursors, 76% of haloacetic acid （HAAs） precursors, 83%of trichloracetic aldehyde （CH） precursor, 77% of dichloroaeetonitrile （DCAN） precursor, 51% of trichloroacetonitrile （TCAN） precursor, 96% of 1,1,1- trichloroacetone （TCP） precursor and 63% of trichloroni- tromethane （TCNM） precursor. Hydrophobic organic matter was converted into hydrophilic organic matter during ozonation/UF, while the organic matter with molecular weight of 1000-3000 Da was remarkably decreased and converted into lower molecular weight organic matter ranged from 200-500 Da. DOC had a close linear relationship with the formation potential of DBPs.

关键词： ceramic ultrafiltration(UF) ozonation organic matter hydrophilic hydrophobic disinfection by-products