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combining material characterization with single and multi-oxyanion adsorption for mechanistic study of chromate removal by cationic hydrogel

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Journal of Environmental Sciences 2011年第6期23卷 1004-1010页

作者： irene m.c.lo Samuel c.N.Tang Department of civil and Environmental Engineering The Hong Kong University of Science and TechnologyHong KongChina

cationic hydrogel with magnetic property was synthesized via radical polymerization and its removal capacity of chromate from contaminated water was found to be 200 mg/*** Fourier transform infrared spectroscopy（FT-iR） study,the mechanism of chromate removal by hydrogel was found to be non-specific adsorption,mainly due to ion exchange,as evidenced by the positively charged functional group,trimethyl ammonium-N＋（cH3）3,in the *** were accordingly determined by testing di？erent oxyanion adsorption onto the *** results of the chromate adsorption experiments illustrated that the amount of chromate adsorbed was nearly equal to that of the chloride released from the hydrogel,which is part of the evidence for ion *** and multi-oxyanion adsorption experiments were also performed,and it was demonstrated that ion removal was species independent,but charge dependent,another characteristic of the ion exchange *** was found that the same Langmuir model can be applied to best fit the findings of single and multi-oxyanion adsorption,which further indicates the mechanism of chromate removal is attributed to ion *** view of the above,the background anions compete for adsorption sites with chromate,evidenced by inhibitive chromate removal in the presence of background electrolytes in the batch studies,further echoing the ion exchange mechanism.

关键词： adsorption magnetic hydrogel mechanism ion exchange oxyanion

Seminal biomarkers for the evaluation of male infertility

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Asian Journal of Andrology 2016年第3期18卷 426-433,I0009页

作者： Jared m Bieniek Andrei P Drabovich Kirk c lo Department of Urology Hartford Hospital Hartford CT USA Department of clinical Biochemistry University Health Network Toronto ON Canada Department ofLaboratory medicine and Pathobiology University of Toronto Toronto ON Canada Department of Surgery Division of Urology Mount Sinai Hospital Toronto ONCanada.

For men struggling to conceive with their partners, diagnostic tools are limited and often consist of only a standard semen analysis. This baseline test serves as a crude estimation of male fertility, leaving patients and clinicians in need of additional diagnostic biomarkers. Seminal fluid contains the highest concentration of molecules from the male reproductive glands, therefore, this review focuses on current and novel seminal biomarkers in certain male infertility scenarios, including natural fertility, differentiating azoospermia etiologies, and predicting assisted reproductive technique success. currently available tests include antisperm antibody assays, DNA fragmentation index, sperm fluorescence in situ hybridization, and other historical sperm functional tests. The poor diagnostic ability of current assays has led to continued efforts to find more predictive biomarkers. Emerging research in the fields of genomics, epigenetics, proteomics, transcriptomics, and metabolomics holds promise for the development of novel male infertility biomarkers. Seminal protein-based assays of TEXi01, Ecm 1, and AcRV1 are already available or under final development for clinical use. Additional panels of DNA, RNA, proteins, or metabolites are being explored as we attempt to understand the pathophysiologic processes of male infertility. Future ventures will need to continue data integration and validation for the development of clinically useful infertility biomarkers to aid in male infertility diagnosis, treatment, and counseling.

关键词： assisted reproductive techniques diagnosis male infertility, semen

Size Effects of the critical Temperature in Ferroelectric Thin Films

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communications in Theoretical Physics 2007年第7期48卷 183-188页

作者： V.c.lo institute of Physics and center for condensed matter Physics Chinese Academy of SciencesBeijing 100080China

The size effects of the critical behaviors for the systems of interacting spins are discussed extensively *** this paper,the finite-size dependence of the critical temperature and susceptibility of the ferroelectric thinfilm are investigated numerically based on the four-state Potts model with the nearest-neighbor interactions between thedipole *** four orientations of the domains exist in the ferroelectric film and the movement of the domainwalls determines the polarization switching process besides the boundary conditions of the *** critical exponentsare obtained and our investigations show that the boundary conditions play the important roles for the ferroelectricproperties of the thin films and the critical behavior of the thin films strongly depends on the feature of the surface.

关键词： ferroelectric thin film critical temperature size effects

Simultaneous removal of chromium and arsenate from contaminated groundwater by ferrous sulfate:Batch uptake behavior

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Journal of Environmental Sciences 2011年第3期23卷 372-380页

作者： Xiaohong Guan Haoran Dong Jun ma irene m. c. lo State Key Laboratory of Urban Water Resource and Environment Harbin Institute of Technology Harbin 150090 China Department of civil and Environmental Engineering The Hong Kong University of Science and Technology Hong Kong 999077 China

chromium and/or arsenate removal by Fe（Ⅱ） as a function of pH, Fe（Ⅱ） dosage and initial cr（Ⅵ）/As（Ⅴ） ratio were examined in batch tests. The presence of arsenate reduced the removal efficiency of chromium by Fe（Ⅱ）, while the presence of chromate significantly increased the removal efficiency of arsenate by Fe（Ⅱ） at pH 6-8, in the absence of arsenate, chromium removal by Fe（Ⅱ） increased to a maximum with increasing pH from 4 to 7 and then decreased with a further increase in pH. The increment in Fe（Ⅱ） dosage resulted in an improvement in chromium removal and the improvement was more remarkable under alkaline conditions than that under acidic conditions. chromium removal by Fe（Ⅱ） was reduced to a larger extent under neutral and alkaline conditions than that under acidic conditions due to the presence of 10 μtmol/L arsenate. The presence of 20 μmol/L arsenate slightly improved chromium removal by Fe（Ⅱ） at pH 3.9-5,8, but had detrimental effects at pH 6.7-9.8. Arsenate removal was improved significantly at pH 4-9 due to the presence of 10μmol/L chromate at Fe（Ⅱ） dosages of 20-60 μmol/L. Elevating the chromate concentration from 10 to 20μmol/L resulted in a further improvement in arsenate removal at pH 4.0-4.6 when Fe（Ⅱ） was dosed at 30-60 μmol/L.

关键词： chromium removal arsenate removal ferrous iron groundwater treatment

Exact Time-Dependent Wave Functions of a confined Time-Dependent Harmonic Oscillator with Two moving Boundaries

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communications in Theoretical Physics 2009年第11期52卷 820-824页

作者： c.F.lo institute of Theoretical Physics and Department of Physics The Chinese University of Hong Kong

By applying the standard analytical techniques of solving partial differential equations, we have obtained the exact solution in terms of the Fourier sine series to the time-dependent Schrodinger equation describing a quantum one-dimensional harmonic oscillator of time-dependent frequency confined in an infinite square well with the two walls moving along some parametric trajectories. Based upon the orthonormal basis of quasi-stationary wave functions, the exact propagator of the system has also been analytically derived. Special eases like （i） a confined free particle, （ii） a confined time-independent harmonic oscillator, and （iii） an aging oscillator are examined, and the corresponding time- dependent wave functions are explicitly determined. Besides, the approach has been extended to solve the case of a confined generalized time-dependent harmonic oscillator for some parametric moving boundaries as well.

关键词： infinite square well harmonic oscillator moving boundaries Fourier series

can we grow sperm？ A translational perspective on the current animal and human spermatogenesis models

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Asian Journal of Andrology 2011年第5期13卷 677-682页

作者： Kirk c lo Trustin Domes Department of Surgery University of Toronto Toronto Ont. Canada Division of Urology Department of Surgery Mount Sinai Hospital Toronto Ont. Canada

There have been tremendous advances in both the diagnosis and treatment of male factor infertility; however, the mechanisms responsible to recreate spermatogenesis outside of the testicular environment continue to elude andrologists. Having the ability to ＇grow＇ human sperm would be a tremendous advance in reproductive biology with multiple possible clinical applications, such as a treatment option for men with testicular failure and azoospermia of multiple etiologies. To understand the complexities of human spermatogenesis in a research environment, model systems have been designed with the intent to replicate the testicular microenvironment. currently, there are both in vivoand in vitro model systems. in vivo model systems involve the transplantation of either spermatogonial stem cells or testicular xenographs. in vitro model systems involve the use of pluripotent stem cells and complex coculturing and/or three-dimensional culturing techniques. This review discusses the basic methodologies, possible clinical applications, benefits and limitations of each model system. Although these model systems have greatly improved our understanding of human spermatogenesis, we unfortunately have not been successful in demonstrating complete human spermatogenesis outside of the testicle.

关键词： fertility preservation spermatogenesis models spermatogonial stem cells

A comparative analysis of alternative approaches to fitting species-abundance models

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Journal of Plant Ecology 2012年第1期5卷 32-45页

作者： Sean R.connolly loïc m.Thibaut School of marine and Tropical Biology and ARc centre of Excellence for coral Reef Studies James Cook UniversityTownsvilleQueensland 4811Australia

Aims Fits of species-abundance distributions to empirical data are increasingly used to evaluate models of diversity maintenance and community structure and to infer properties of communities,such as species *** distributions predicted by several models are the Poisson lognormal(PLN)and the negative binomial(NB)distribution;however,at least three different ways to parameterize the PLN have been proposed,which differ in whether unobserved species contribute to the likelihood and in whether the likelihood is conditional upon the total number of individuals in the *** of these has an analogue for the ***,we propose a new formulation of the PLN and NB that includes the number of unobserved species as one of the estimated *** investigate the performance of parameter estimates obtained from this reformulation,as well as the existing alternatives,for drawing inferences about the shape of species abundance distributions and estimation of species *** We simulate the random sampling of a fixed number of individuals from lognormal and gamma community relative abundance distributions,using a previously developed‘individual-based’bootstrap *** use a range of sample sizes,community species richness levels and shape parameters for the species abundance distributions that span much of the realistic range for empirical data,generating 1000 simulated data sets for each parameter *** then fit each of the alternative likelihoods to each of the simulated data sets,and we assess the bias,sampling variance and estimation error for each *** Findings Parameter estimates behave reasonably well for most parameter values,exhibiting modest levels of median ***,for the NB,median error becomes extremely large as the NB approaches either of two limiting *** both the NB and PLN,>90%of the variation in the error in model parameters across parameter sets is explained by three quantities that corresponded to t

关键词： Poisson lognormal negative binomial Poisson gamma species-abundance distributions species richness

Preparation of cross-linked magnetic chitosan with quaternary ammonium and its application for cr(Ⅵ) and P(Ⅴ) removal

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Journal of Environmental Sciences 2014年第12期26卷 2379-2386页

作者： Wei Yao Pinhua Rao irene m.c.lo Wenqi Zhang Wenrui Zheng School of chemistry and chemical Engineering Shanghai University of Engineering Science Department of civil and Environmental Engineering The Hong Kong University of Science and Technology

Pollutants that exist in anionic species are issues of concern in water treatment. compared to cationic pollutants, the removal of anionic pollutants by adsorption is more difficult because most adsorbents carry predominantly negative charges in neutral and alkaline environments. in this study, a cross-linked chitosan derivative with quaternary ammonium and magnetic properties（Qm-chitosan） was prepared and employed to remove chromium（Vi） and phosphorus（V）（cr（Vi） and P（V）） from aqueous environments. The Qm-chitosan was characterized by Fourier transform infrared spectrometry（FT-iR）,thermogravimetric analysis（TGA）, energy dispersive X-ray（SEm-EDX） and zeta *** experiments show that Qm-chitosan can effectively remove cr（Vi） and P（V）, and the main mechanism was believed to be electrostatic interaction. A pseudosecond-order model was fitted to describe the kinetic processes of cr（Vi） and P（V） removal. The adsorption isotherms of both cr（Vi） and P（V） on the Qm-chitosan were well fitted by the Langmuir isotherm equation. The saturated adsorption capacity of P（V）（2.783 mmol/g） was found to be higher than that of cr（Vi）（2.323 mmol/g）, resulting from the size of the H2PO-4ions being smaller than that of the Hcr O-4ions. However, the theoretical calculation and experimental results showed that Qm-chitosan had a stronger affinity for cr（Vi） than P（V）. The adsorption–desorption of the Qm-chitosan was evaluated, and high regeneration rates were demonstrated.

关键词： magnetic chitosan Quaternary ammonium cr(Vi) P(V) Adsorption

Remittances for Disaster Risk management: Perspectives from Pacific island migrants Living in New Zealand

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international Journal of Disaster Risk Science 2018年第3期9卷 331-343页

作者： Jenna Pairama loc Le Dé Public Health and Psychosocial Studies Faculty of Health and Environmental Sciences Auckland University of Technology Emergency and Disaster management Faculty of Health and Environmental Sciences Auckland University of Technology

in many low-income countries, migrant remittances are essential in sustaining people's livelihoods and become even more important during and after ***, policymakers, and practitioners increasingly emphasize the need to better support this people-based mechanism, so disaster risk can be reduced. This suggests the importance of understanding migrants' perspectives on the remittance channels used and the challenges and opportunities of supporting remittances. However, such information is largely missing. Drawing on interviews and a focus group discussion carried out with Pacific island migrants living in New Zealand, the article identifies the capacity of migrants to utilize different remittance channels and resources to assist those affected in their country of origin. challenges faced include high transfer fees, lack of information and support from external stakeholders, and limited resources to effectively send both individual and collective remittances. The article concludes that there is a serious need to involve a large array of stakeholders in finding ways to better support remittances for disaster risk management, including migrants, government agencies, the private sector, nongovernmental organizations, and those receiving remittances.

关键词： Disaster risk management migration New Zealand Pacific island countries Remittances