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Influence of stabilizers on the antimicrobial properties of silver nanoparticles introduced into natural water

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Journal of environmental Sciences 2014年第3期26卷 542-549页

作者： Aleksandra Burkowska-But Grzegorz Sionkowski Maciej Walczak department of environmental Microbiology and biotechnology Nicolaus Copernicus University Faculty of Chemistry Nicolaus Copernicus University

Physical, chemical and biochemical properties of silver nanoparticles （AgNPs） depend to a great extent on their size, shape, size distribution, and stabilizers located on their surface. This study focused on two typical stabilizers, namely citrates （cit）, low molecular ions protecting nanoparticles by electrostatic repulsion, and polyvinylpyrrolidone （PVP）, a hydrophilic, neutral, high molecular polymer protecting nanoparficles by steric stabilization. Natural bacterioplankton was collected from a eutrophic, downtown lake and exposed to five concentrations （0.1-5 mg/L） of AgNPs-PVP and AgNPs-cit. Responses were monitored after 1, 3, 5 and 7 days of exposure, by evaluating the survival rate of bacteria, their respiratory activity, and the general activity of extracellular esterases. A significantly better （greater） survival rate of bacterioplankton was observed in water with an addition of AgNPs-cit. The inhibition of extracellular esterases was observed only in samples containing AgNPs-PVP. The inhibitory effect increased proportionally to the concentration of AgNPs-PVP applied. Within the studied concentration range, there was no statistically significant inhibition of bacterioplankton respiratorv activity bv AgNPs-PVP and AgNPs-cit.

关键词： silver nanoparticles antimicrobial properties nanoparticles in environment

Effects of particle composition and environmental parameters on catalytic hydrodechlorination of trichloroethylene by nanoscale bimetallic Ni-Fe

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Journal of environmental Sciences 2014年第5期26卷 1162-1170页

作者： Jianjun Wei Yajing Qian Wenjuan Liu Lutao Wang Yijie Ge Jianghao Zhang Jiang Yu Xingmao Ma department of environmental Science and engineering Beijing University of Chemical Technology department of Civil and environmental engineering Southern Illinois University Carbondale

Catalytic nickel was successfully incorporated into nanoscale iron to enhance its dechlorination efficiency for trichloroethylene （TCE）, one of the most commonly detected chlorinated organic compounds in groundwater. Ethane was the predominant product. The greatest dechlorination efficiency was achieved at 22 molar percent of nickel. This nanoscale Ni-Fe is poorly ordered and inhomogeneous; iron dissolution occurred whereas nickel was relatively stable during the 24-hr reaction. The morphological characterization provided significant new insights on the mechanism of catalytic hydrodcchlorination by bimetallic nanoparticles. TCE degradation and ethane production rates were greatly affected by environmental parameters such as solution pH, temperature and common groundwater ions. Both rate constants decreased and then increased over the pH range of 6.5 to 8.0, with the minimum value occurring at pH 7.5. TCE degradation rate constant showed an increasing trend over the temperature range of 10 to 25℃. However, ethane production rate constant increased and then decreased over the range, with the maximum value occurring at 20℃, Most salts in the solution appeared to enhance the reaction in the first half hour but overall they displayed an inhibitory effect. Combined ions showed a similar effect as individual salts.

关键词： nanoscale Ni-Fe trichloroethylene hydrodechlorination catalytic dechlorination composition environmental parameters

Polymerizable Ionic Liquid Copolymer P(MMA-co-BVIm-Br) and Its Effect on the Surface Wettability of PVDF Blend Membranes

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Chinese Journal of Polymer Science 2015年第6期33卷 857-868页

作者：杜春慧 Xu-min Ma Chun-jin Wu Mei-qiang Cai Meng-xin Hu Ting Wang School of environmental Science and engineering Zhejiang Gongshang University Schoolof Food Science and biotechnology Zhejiang Gongshang University

Polymerizable ionic liquid copolymer P（MMA-co-BVIm-Br） was synthesized by radical polymerization technique, and characterized by Fourier transform infrared spectrometry （FTIR）, 1H Nuclear magnetic resonance （1H-NMR） and gel permeation chromatography （GPC）. The resulting copolymer was used to prepare poly（vinylidene fluoride）（PVDF） blend membranes via a phase inversion method. The effects of the copolymer on the polymorphism, surface wettability and zeta potential （0 of the blend membranes were investigated by ATR-FTIR, contact angle instrument and zeta potential analyzer. Scanning electron microscopy （SEM and SEM-EDS） was also applied to investigate the morphology and the surface element changes of the fabricated membranes. The results indicated that P（MMA-co-BVIm-Br） copolymer existed on the surface of the membrane which made the blend membrane have a positive surface during the experimental pH range. The copolymer was also in favor of the formation of βcrystal phase in PVDF membranes. The contact angle experiment indicated that P（MMA-co-BVIm-Br） copolymer could switch the wettability of the blend membranes from hydrophilic to hydrophobic by exchanging Br- anion with PF6-. Compared with pure PVDF membranes, the water flux and water recovery flux of the blend membranes were enhanced obviously. The results from the flux recovery ratio （FR） and total fouling ratio （Rt） all suggested that the blend membranes had good anti-fouling properties.

关键词： PVDF membrane Polymerized ionic liquid Surface wettability Anti-fouling performance.

Modeling ocean wave propagation under sea ice covers

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Acta Mechanica Sinica 2015年第1期31卷 1-15页

作者： Xin Zhao Hayley H. Shen Sukun Cheng department of Civil and environmental engineering Clarkson University

Operational ocean wave models need to work globally, yet current ocean wave models can only treat ice covered regions crudely. The purpose of this paper is to provide a brief overview of ice effects on wave propagation and different research methodology used in studying these effects. Based on its proximity to land or sea, sea ice can be classified as： landfast ice zone, shear zone, and the marginal ice zone. All ice covers attenuate wave energy. Only long swells can penetrate deep into an ice cover. Being closest to open water, wave propagation in the marginal ice zone is the most complex to model. The physical appearance of sea ice in the marginal ice zone varies. Grease ice, pancake ice, brash ice, floe aggregates, and continuous ice sheet may be found in this zone at different times and locations. These types of ice are formed under different thermalmechanical forcing. There are three classic models that describe wave propagation through an idealized ice cover： mass loading, thin elastic plate, and viscous layer models. From physi cal arguments we may conjecture that mass loading model is suitable for disjoint aggregates of ice floes much smaller than the wavelength, thin elastic plate model is suitable for a con tinuous ice sheet, and the viscous layer model is suitable for grease ice. For different sea ice types we may need different wave ice interaction models. A recently proposed viscoelas tic model is able to synthesize all three classic models into one. Under suitable limiting conditions it converges to the three previous models. The complete theoretical framework for evaluating wave propagation through various ice covers need to be implemented in the operational ocean wave models. In this review, we introduce the sea ice types, previous wave ice interaction models, wave attenuation mechanisms,the methods to calculate wave reflection and transmission between different ice covers, and the effect of ice floe breaking on shaping the sea ice morphology. Labora

关键词： Ocean waves Sea ice Cryospheric change

Transient curvilinear-coordinate based fully nonlinear model for wave propagation and interactions with curved boundaries

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Journal of Hydrodynamics 2018年第4期30卷 549-563页

作者： Yu-Hsiang Chen Keh-Han Wang department of Civil and environmental engineering University of Houston

This paper presents a newly developed 3-D fully nonlinear wave model in a transient curvilinear coordinate system to simulate propagation of nonlinear waves and their interactions with curved boundaries and cylindrical structures. A mixed explicit and implicit finite difference scheme was utilized to solve the transformed governing equation and boundary conditions in grid systems fitting closely to the irregular boundaries and the time varying free surface. The model＇s performance was firstly tested by simulating a solitary wave propagating in a curved channel. This three-dimensional solver, after comparing the results with those obtained from the generalized Boussinesq（g B） model, is demonstrated to be able to produce stable and reliable predictions on the variations of nonlinear waves propagating in a channel with irregular boundary. The results for modeling a solitary wave encountering a vertical cylinder are also presented. It is found the computed wave elevations and hydrodynamic forces agree reasonably well with the experimental measurements and other numerical results.

关键词： Solitary wave curvilinear coordinate transformation curved channel wave scattering hydrodynamic forces

Beyond statistical significance:Embracing minimal clinically important difference for better patient care

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World Journal of Methodology 2025年第1期15卷 33-41页

作者： Naveen Jeyaraman Madhan Jeyaraman Swaminathan Ramasubramanian Sangeetha Balaji Sathish Muthu department of Orthopaedics ACS Medical College and HospitalDr MGR Educational and Research InstituteChennai 600077Tamil NaduIndia department of Research Methods Orthopaedic Research GroupCoimbatore 641045Tamil NaduIndia department of Orthopaedics Government Medical CollegeOmandurar Government EstateChennai 600002Tamil NaduIndia department of biotechnology Faculty of EngineeringKarpagam Academy of Higher EducationCoimbatore 641021Tamil NaduIndia department of Orthopaedics Government Medical CollegeKarur 639004Tamil NaduIndia

The minimal clinically important difference(MCID)represents a pivotal metric in bridging the gap between statistical significance and clinical relevance,addressing the direct impact of medical interventions from the patient's *** comprehensive review analyzes the evolution,applications,and challenges of MCID across medical specialties,emphasizing its necessity in ensuring that clinical outcomes not only demonstrate statistical significance but also offer genuine clinical utility that aligns with patient expectations and *** discuss the evolution of MCID since its inception in the 1980s,its current applications across various medical specialties,and the methodologies used in its calculation,highlighting both anchor-based and distribution-based ***,the paper delves into the challenges associated with the application of MCID,such as methodological variability and the interpretation difficulties that arise in clinical *** for the future include standardizing MCID calculation methods,enhancing patient involvement in setting MCID thresholds,and extending research to incorporate diverse global *** steps are critical to refining the role of MCID in patient-centered healthcare,addressing existing gaps in methodology and interpretation,and ensuring that medical interventions lead to significant,patient-perceived improvements.

关键词： Minimal clinically important difference Patient-centered care Clinical relevance Global health

Effect of water chemistry on the aggregation and photoluminescence behavior of carbon dots

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Journal of environmental Sciences 2018年第3期30卷 223-235页

作者： Mohamed Bayati Jingjing Dai Austin Zambrana Chloe Rees Maria Fidalgo de Cortalezzi department of Civil and environmental engineering University of Missouri

Carbon dots are rapidly emerging carbon-based nanomaterials that,due to their growing applications,will inevitable find their way to natural waters;however,their environmental fate is mostly *** dots with different surface functionality were fabricated and characterized by TEM and *** surface charge,given by the zeta potential,and their hydrodynamic diameter in suspension were investigated under a variety of environmentally relevant *** effect of ionic strength was studied in the presence of monovalent（NaCl）and divalent（CaCl2）cations,for p H levels from 3 to 11;humic acid was used as a model for dissolved natural organic *** potential energies of interactions were modeled by classical DLVO *** experimental results showed that water chemistry altered the surface charge of the nanomaterials,but their hydrodynamic size could not be correlated to those *** of specific interactions was found for the amino functionalized particles in most cases,as well as the plain carbon dots in the presence of Ca^（2＋）and humic *** remained largely stable in suspension,with some exception at the highest ionic strength *** theory did not adequately capture the aggregation behavior of the ***,cation and/or humic acid adsorption negatively affected the emission intensity of the particles,suggesting limitations to their use in natural water sensing *** particular stability shown by the carbon dots results in exposure to organisms in the water column and the possibility of contamination transported to significant distances from their source.

关键词： Carbon dots Photoluminescence Aggregation

Decontamination of alachlor herbicide wastewater by a continuous dosing mode ultrasound/Fe^(2+)/H_2O_2 process

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Journal of environmental Sciences 2014年第6期26卷 1332-1339页

作者： Chikang Wang Chunghan Liu department of environmental engineering and Health Yuanpei University

We used a ultrasound/Fe2＋/H2O2 process in continuous dosing mode to degrade the alachlor. Experimental results indicated that lower pH levels enhanced the degradation and mineralization of alachlor. The maximum alachlor degradation （initial alachlor concentration of 50 mg/L） was as high as 100% at pH 3 with ultrasound of 100 Watts, 20 mg/L of Fe2＋, 2 mg/min of H2O2 and 20℃ within 60 min reaction combined with 46.8% total organic carbon removal. Higher reaction temperatures inhibited the degradation of alachlor. Adequate dosages of Fe2＋ and H2O2 in ultrasound/Fe2＋/H2O2 process not only enhance the degradation efficiency of alachlor but also save the operational cost than the sole ultrasound or Fenton process. A continuous dosing mode ultrasound/Fe2＋/H2O2 process was proven as an effective method to degrade the alachlor.

关键词： alachlor continuous dosing mode degradation total organic carbon ultrasound/Fe2+/H2O2 process

Ferrierite vs. γ-Al_2O_3: The superiority of zeolites in terms of water-resistance in vapour-phase dehydration of methanol to dimethyl ether

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Journal of Energy Chemistry 2019年第3期28卷 162-169页

作者： Enrico Catizzone Massimo Migliori Antonio Purita Girolamo Giordano department of environmental and Chemical engineering University of Calabria

The catalytic conversion of methanol to dimethyl ether(DME) over a series of home-made FER-type zeolites having different acidities and commercial γ-Al_2O_3 has been studied with the aim to understand the impact of adding water in the reactant stream on the catalytic behavior on investigated materials. Cofeeding water with methanol, the alcohol conversion was slightly reduced over the investigated zeolites while the catalytic activity of γ-Al_2O_3, the traditional catalyst of MeOH-to-DME conversion, was strongly inhibited. It was also found that, for the investigated zeolites, both the amount and the initial deposition rate of the coke formed during the reaction were reduced when water was co-fed with methanol while no significant effects on both methanol conversion and DME selectivity were observed under the investigated conditions.

关键词： Ferrierite Zeolites Methanol dehydration Dimethyl ether Coke