87 research outputs found
Huo zhuo Yang Shangkun Luo Ruiqing
No full text红卫兵串联联络站绘.文字:活捉 楊尚昆 羅瑞卿;下款: 红卫兵串联联络站绘 一九六七季三月九日.裝裱後高寬: 117 x 47 cm.Hong wei bing chuan lian lian luo zhan hui.Wen zi : huo zhuo Yang Shangkun Luo Ruiqing; Xia kuan : hong wei bing chuan lian lian luo zhan hui 1967 ji 3 yue 9 ri.Zhuang biao hou gao kuan : 111 x 47 cm
Huo zhuo Luo Ruiqing, Yang Shangkun
No full text珠江水利系统造反兵团绘."一九六七.五.一"题名及丛书由编目者拟定.Zhujiang shui li xi tong zao fan bing tuan hui."Yi jiu liu qi. wu. yi"Ti ming ji cong shu you bian mu zhe ni ding
Huo zhuo Yang Shangkun, Luo Ruiqing
No full text廣州東風总部宣.题名及丛书由编目者拟定.Guangzhou dong feng zong bu xuan.Ti ming ji cong shu you bian mu zhe ni ding
Mechanism study of virus removal in membrane filtration and the application to improve virus removal
No full textTo overcome the severer droughts in recent climate change, direct potable water reuse has been in practice and a wider acceptance can be expected with a reliable control of the water quality. Pathogenic viruses in municipal wastewater can result in outbreaks of virus infection without sufficient removal. Membrane bioreactor (MBR) has shown its promise to remove virus in municipal wastewater treatment, but the major concern is the trade-off between the water permeate flux and the virus removal efficiency. The objective of this study is to understand factors controlling virus removal in low pressure membrane filtration.
The virus transport in the membrane surface vicinity was investigated with the dynamic of virus removal. By filtering human adenovirus 2 (HAdV-2) with a 0.2 µm hollow fiber membrane, the virus removal efficiency was observed to be a function of the number of the total filtered virus (N_v). When N_v was low, the HAdV-2 removal efficiency decreased with N_v, while the permeate flux did not significantly change. The decrease of virus removal was attributed to the accumulation of rejected viruses in the membrane surface vicinity, leading to an increase of the local virus concentration. Further increase of N_v leaded to an increase of virus removal as a function of N_v, accompanied by a decrease of the permeate flux. By fitting the permeate flux decrease with the pore blockage-cake filtration model, it was determined that HAdV-2 fouled the membrane and decreased the effective membrane pore size, leading to the enhanced virus removal and the decreased permeate flux. It was also found that, the aim of high virus removal with the high permeate flux could be achieved by maintaining the pristine membrane and avoiding virus accumulation.
To quantitatively evaluate the virus adsorption on membrane, the adsorption kinetics was investigated with a quartz crystal microbalance with dissipation (QCM-D). Both in the presence and absence of foulants, the HAdV-2 adsorption onto membrane was determined to be irreversible in 3 to 100 mM CaCl2 solutions. The kinetics of HAdV-2 adsorption could be explained with the random sequential adsorption (RSA) model. A decrease of the virus adsorption rate was observed over the adsorption time, because previously adsorbed virions would exert repulsive forces towards the virion approaching the membrane surface. Similar observation was found even in the HAdV-2 favorable adsorption. The knowledge of virus adsorption indicated that virus adsorbed onto the membrane formed a monolayer to decrease the effective pore size, which enhances the pore blockage and cake layer formation.
The mechanism study illustrates the process of virus passage through the membrane. At the beginning of filtration, the observed high virus removal can be attributed to the virus adsorption onto the pristine membrane surface, and that the local concentration of suspended virus in the membrane surface vicinity is similar to the bulk solution. As filtration goes on, virions adsorbed on the membrane surface repel incoming virions and keep them suspended in the membrane surface vicinity. The convective transport and the diffusive transport jointly push the virus towards the membrane surface, increasing the local virus concentration in the membrane surface vicinity and decreasing the observed virus removal efficiency. In the long-term filtration, the virus adsorption facilitates foulant layer development, which translates into the improved virus removal with the decreased permeate flux.
The mechanism study indicates that to avoid virus adsorption and approaching membrane surface could be effective in maintaining the high virus removal and the high permeate flux at the beginning of filtration. This hypothesis was tested with a zwitterionic polymer grafted membrane. The repulsive interaction forces between incoming particles and the membrane surface was validated with atomic force microscope (AFM) in the contact mode. The repulsive forces keep a distance between viruses and the membrane surface, where the convective force is low since the flow velocity decays with the distance away from the membrane pores. The enhanced virus removal by the grafted membrane was observed in our bench-scale filtration experiment. In the presence of foulants, the permeate flux of the ungrafted membrane significantly decreased while the grafted membrane only had minor decrease in permeate flux. The grafted membrane achieved both higher virus removal and higher membrane permeate flux than the ungrafted membrane in the presence of foulants. The mechanism knowledge is validated by the enhanced virus removal of the grafted membrane. Practically, the zwitterionic polymer grafting method shows its promise to control viruses in water reuse.Submission published under a 24 month embargo labeled 'Closed Access', the embargo will last until 2018-12-01The student, Ruiqing Lu, accepted the attached license on 2016-11-21 at 10:58.The student, Ruiqing Lu, submitted this Dissertation for approval on 2016-11-21 at 11:10.This Dissertation was approved for publication on 2016-11-22 at 11:49.DSpace SAF Submission Ingestion Package generated from Vireo submission #10282 on 2017-02-28 at 14:41:41Made available in DSpace on 2017-03-01T17:01:23Z (GMT). No. of bitstreams: 4
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Previous issue date: 2016-11-22Embargo set by: Seth Robbins for item 98693
Lift date: 2019-03-01T17:02:22Z
Reason: Author requested closed access (OA after 2yrs) in Vireo ETD systemEmbargo set by: Seth Robbins for item 98693
Lift date: 2019-03-01T17:03:32Z
Reason: Author requested closed access (OA after 2yrs) in Vireo ETD systemEmbargo set by: Seth Robbins for item 98693
Lift date: 2019-03-01T17:05:02Z
Reason: Author requested closed access (OA after 2yrs) in Vireo ETD systemEmbargo set by: Seth Robbins for item 98693
Lift date: 2019-03-01T17:06:55Z
Reason: Author requested closed access (OA after 2yrs) in Vireo ETD systemLimited Restriction Lifted for Item 98693 on 2019-03-02T10:15:33Z
The people defeated Japanese fascism and they can certainly defeat U.S. imperialism too : speech at the rally of the people of all circles in Peking in celebration of the 20th anniversary of the victory of the War of Resistance against Japan
No full textIncludes bibliographical references.The International Labour and Radical History Pamphlet Collection consists of over 2200 pamphlets representing a broad spectrum of leftist opinion, including communists, socialists, liberal reformers, trade unionists, civil libertarians and antiwar activists. The majority of the pamphlets are in English and were published between 1920-1970 in the United States, the Soviet Union, Great Britain, Canada and China. There are also a number of earlier Fabian Society publications. Further information: http://www.library.mun.ca/asc/specialcollections/collections/radica
Commemorate the victory over German fascism! Carry the struggle against U.S. imperialism through to the end
No full textThe International Labour and Radical History Pamphlet Collection consists of over 2200 pamphlets representing a broad spectrum of leftist opinion, including communists, socialists, liberal reformers, trade unionists, civil libertarians and antiwar activists. The majority of the pamphlets are in English and were published between 1920-1970 in the United States, the Soviet Union, Great Britain, Canada and China. There are also a number of earlier Fabian Society publications. Further information: http://www.library.mun.ca/asc/specialcollections/collections/radica
Riverine nitrogen footprint of agriculture in the Mississippi–Atchafalaya River Basin: do we trade water quality for crop production?
No full textIncreasing food and biofuel demands have led to the cascading effects from cropland expansions, raised fertilizer use, to increased riverine nitrogen (N) loads. However, little is known about the current trade-off between riverine N pollution and crop production due to the lack of predictive understanding of ecological processes across the land-aquatic continuum. Here, we propose a riverine N footprint (RNF) concept to quantify how N loads change along with per unit crop production gain. Using data synthesis and a well-calibrated hydro-ecological model, we find that the RNF within the Mississippi–Atchafalaya River Basin peaked at 1.95 g N kg−1 grain during the 1990s, and then shifted from an increasing to a decreasing trend, reaching 0.65 g N kg−1 grain in the 2010s. This implies decoupled responses of crop production and N loads to key agricultural activities approximately after 2000, but this pattern varies considerably among sub-basins. Our study highlights the importance of developing a food–energy–water nexus indicator to examine the region-specific trade-offs between crop production and land-to-aquatic N loads for achieving nutrient mitigation goals while sustaining economic gains.This letter is published as Lu, Chaoqun, Jien Zhang, Bo Yi, Ignacio Calderon, Hongli Feng, Ruiqing Miao, David Hennessy, Shufen Pan, and Hanqin Tian. "Riverine nitrogen footprint of agriculture in the Mississippi–Atchafalaya River Basin: do we trade water quality for crop production?." Environmental Research Letters 18, no. 11 (2023): 114043. doi:10.1088/1748-9326/ad0128. © 2023 The Author(s).Original content from this work may be used under the terms of the Creative Commons Attribution 4.0 licence. Any further distribution of this work must maintain attribution to the author(s) and the title of the work, journal citation and DOI.This work is supported by the Iowa Nutrient Research Center, the Postdoc seed Grant award of Iowa State University, NSF Grant (1903722), and NSF CAREER (1945036)
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