196,054 research outputs found
Production, characterization, and toxicology of environmentally relevant nanoplastics: a review
No full textNanoplastic pollution is poorly known, in particular because research is actually mainly done using synthetic polymeric nanospheres that are not representative of environmental nanoplastics, which are very diverse in their composition, size, and shape. Here we review environmentally relevant nanoplastics with focus on their production, characterization, quantification, stability, aggregation, and toxicity. Production of environmentally relevant nanoplastics can be done by mechanical and physicochemical methods. Toxicological studies focus on internalization and toxicity on human cell lines, and bioaccumulation and systemic effects on model organisms
Quantitative evaluation of true-to-life nanoplastics using UV-visible spectroscopy and comparative analytical techniques
No full texteditorial reviewedThe growing concern over microplastic pollution has led to increased focus on environmental nanoplastics, which are smaller, more dynamic, and present unique challenges in both quantification and risk assessment. Nanoplastics exhibit high variability in size, shape, chemical composition, and surface chemistry, complicating their detection and quantification through conventional analytical techniques developed for nanomaterial analysis. One of the key challenges in nanoplastic research is the lack of realistic, environmentally relevant test materials that accurately mimic the characteristics of nanoplastics found in natural environments. In this study, we generated polystyrene-based nanoplastics from fragmented plastic items and use them to produce controlled test materials for evaluating and comparing analytical techniques under well-defined conditions. Specifically, we investigated the potential of microvolume UV-visible (UV-vis) spectroscopy as a practical and non-destructive technique for the quantification in stock suspensions, aiming to expand the analytical toolkit for environmental nanoplastic research. UV-vis spectroscopy was compared with established mass-based techniques, pyrolysis gas chromatography-mass spectrometry and thermogravimetric analysis, as well as nanoparticle tracking analysis, a number-based method. The comparative analysis demonstrated that UV-vis spectroscopy provides a rapid, accessible, and effective mean of quantifying nanoplastics, especially when sample volumes are limited. Despite some underestimation of nanoplastic concentrations relative to mass-based techniques, UV-vis measurement results were consistent in terms of order of magnitude, showing reliable trends across different methods. This study underscores the potential of UV-vis spectroscopy as a valuable tool for quantifying realistic nanoplastic test materials and supporting the development of future applications in environmental nanoplastic researc
Dr. Duane M. Jackson, Morehouse College, July 2011
No full textThis video is a conversation with Dr. Duane M. Jackson. Dr. Jackson talks about his paper, "Recall and the Serial Position Effect: The Role of Primacy and Recency on Accounting Students' Performance." Jackie Daniel, AUC Woodruff Library, is the interviewer
"Reflections on the subject of Emigration from Europe with a view to Settlement in the United States" By M. Carey.
No full text"Reflections on the subject of Emigration from Europe with a view to Settlement in the United States: containing bried sketches of the moral and political character of those states.
By M. Carey, member of the American philosophical, and of the American Antiquarian Society, and author of The Olive Branch, Cindiciae Hibernicae, essays on banking, on political economy, and on internal improvement.
To which are now added the English editor's comments on the subject; together with Important Advice to Emigrants, and Cautions Against Impositions Practiced in the Outports
Dispelling the Myths Behind First-author Citation Counts
No full textWe conducted a full-scale evaluative citation analysis study of scholars in the XML research field to explore just how different from each other author rankings resulting from different citation counting methods actually are, and to demonstrate the capability of emerging data and tools on the Web in supporting more realistic citation counting methods. Our results contest some common arguments for the continued
use of first-author citation counts in the evaluation of scholars, such as high correlations between author rankings by first-author citation counts and other citation
counting methods, and high costs of using more realistic citation counting methods that are not well-supported by the ISI databases. It is argued that increasingly available digital full text research papers make it possible for citation analysis studies to go beyond what the ISI databases have directly supported and to employ more
sophisticated methods
A Large-Scale 3D Study on Transport of Humic Acid-Coated Goethite Nanoparticles for Aquifer Remediation
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Open AccessFeature PaperArticle
A Large-Scale 3D Study on Transport of Humic Acid-Coated Goethite Nanoparticles for Aquifer Remediation
by Milica Velimirovic 1,2 [OrcID] , Carlo Bianco 3 [OrcID] , Natalia Ferrantello 3, Tiziana Tosco 3, Alessandro Casasso 3 [OrcID] , Rajandrea Sethi 3,*, Doris Schmid 1, Stephan Wagner 1,4 [OrcID] , Kumiko Miyajima 5, Norbert Klaas 5, Rainer U. Meckenstock 6 [OrcID] , Frank von der Kammer 1 and Thilo Hofmann 1,*
1
Department of Environmental Geosciences, Centre for Microbiology and Environmental Systems Science, University of Vienna, Althanstrasse 14, 1090 Vienna, Austria
2
Department of Chemistry, Atomic & Mass Spectrometry–A&MS Research Group, Campus Sterre, Ghent University, Krijgslaan 281-S12, 9000 Ghent, Belgium
3
Department of Environmental, Land and Infrastructure Engineering (DIATI), Politecnico di Torino, corso Duca degli Abruzzi, 24-10129 Torino, Italy
4
Department of Analytical Chemistry, UFZ-Helmholtz Centre for Environmental Research, Permoserstrasse 15, 04318 Leipzig, Germany
5
VEGAS—Research Facility for Subsurface Remediation, University of Stuttgart, Pfaffenwaldring 61, 70569 Stuttgart, Germany
6
Environmental Microbiology and Biotechnology, University Duisburg-Essen, 45141 Essen, Germany
*
Authors to whom correspondence should be addressed.
Water 2020, 12(4), 1207; https://doi.org/10.3390/w12041207
Received: 17 March 2020 / Revised: 10 April 2020 / Accepted: 16 April 2020 / Published: 24 April 2020
(This article belongs to the Special Issue Groundwater and Soil Remediation)
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Abstract
Humic acid-coated goethite nanoparticles (HA-GoeNPs) have been recently proposed as an effective reagent for the in situ nanoremediation of contaminated aquifers. However, the effective dosage of these particles has been studied only at laboratory scale to date. This study investigates the possibility of using HA-GoeNPs in remediation of real field sites by mimicking the injection and transport of HA-GoeNPs under realistic conditions. To this purpose, a three-dimensional (3D) transport experiment was conducted in a large-scale container representing a heterogeneous unconfined aquifer. Monitoring data, including particle size distribution, total iron (Fetot) content and turbidity measurements, revealed a good subsurface mobility of the HA-GoeNP suspension, especially within the higher permeability zones. A radius of influence of 2 m was achieved, proving that HA-GoeNPs delivery is feasible for aquifer restoration. A flow and transport model of the container was built using the numerical code Micro and Nanoparticle transport Model in 3D geometries (MNM3D) to predict the particle behavior during the experiment. The agreement between modeling and experimental results validated the capability of the model to reproduce the HA-GoeNP transport in a 3D heterogeneous aquifer. Such result confirms MNM3D as a valuable tool to support the design of field-scale applications of goethite-based nanoremediation
Dr. Glendon Swarthout
No full textHosted by Roger M. Busfield, MSU Assistant Professor of Speech and Theater, Meet the Author is designed to introduce a general audience to a contemporary author and their work through in-depth interviews. This episode features a conversation between Dr. Glendon Swarthout, prolific author and English professor at MSU, and assistant professors Sam S. Baskett and Theodore B. Strandness
Simulation of thermal plant optimization and hydraulic aspects of thermal distribution loops for large campuses
No full textFollowing an introduction, the author describes Texas A&M University and its utilities system. After that, the author presents how to construct simulation models for chilled water and heating hot water distribution systems. The simulation model was used in a $2.3 million Ross Street chilled water pipe replacement project at Texas A&M University. A second project conducted at the University of Texas at San Antonio was used as an example to demonstrate how to identify and design an optimal distribution system by using a simulation model. The author found that the minor losses of these closed loop thermal distribution systems are significantly higher than potable water distribution systems. In the second part of the report, the author presents the latest development of software called the Plant Optimization Program, which can simulate cogeneration plant operation, estimate its operation cost and provide optimized operation suggestions. The author also developed detailed simulation models for a gas turbine and heat recovery steam generator and identified significant potential savings. Finally, the author also used a steam turbine as an example to present a multi-regression method on constructing simulation models by using basic statistics and optimization algorithms. This report presents a survey of the author??s working experience at the Energy Systems Laboratory (ESL) at Texas A&M University during the period of January 2002 through March 2004. The purpose of the above work was to allow the author to become familiar with the practice of engineering. The result is that the author knows how to complete a project from start to finish and understands how both technical and nontechnical aspects of a project need to be considered in order to ensure a quality deliverable and bring a project to successful completion. This report concludes that the objectives of the internship were successfully accomplished and that the requirements for the degree of Degree of Engineering have been satisfied
Injection of guar gum micro-sized zero-valent iron via direct push – field study
No full textWithin the FP7 AQUAREHAB project (GA 226565), injectable micro-sized zerovalent iron particles (mZVI) were developed and evaluated for in-situ chemical reduction of chlorinated aliphatic hydrocarbons (CAHs). mZVI particles have good reactive properties and a longer life-time than nano-sized particles (nZVI), but need to be stabilised during injection to prevent sedimentation in storage vessels and injection tubes. Earlier we reported on a field scale injection of guar gum stabilized mZVI that was performed in November 2011 as a joined endeavour of several AQUAREHAB partners. More recently, April 2013, an additional larger scale pilot test was performed at another CAH-contaminated site in Belgium, where findings of the first test and numerous lab scale tests were used to work out an improved approach.
At a PCE contaminated test site, 250 kg of mZVI was injected as 5 m3 of 0.45% guar gum stabilized suspension via direct push between 2 and 8 m bgs. The mZVI was injected in a test area of 3 by 6 m via 6 high pressure injections (MIP-IN technology) targeting a radius of influence of 0.5 m. Multilevel monitoring wells were installed at different distances around the injection point, along with temperature sensors and devices specifically developed to detect magnetic particles via measurement of electromagnetic susceptibility. Groundwater samples were taken before the injection and during several months after the injection. After the injection, also several undisturbed soil core samples were collected to evaluate the presence of mZVI (via susceptibility measurements & chemical analyses) and guar gum. The aim of the field test was: (1) to evaluate the feasibility to prepare guar gum stabilised slurry at a larger scale, (2) to evaluate the injectability of the within AQUAREHAB developed mZVI, (3) to determine the radius of influence of the injection, (4) to document the impact of the mZVI on the pollutant concentrations, and (5) to study the fate and added value of the guar gum after the injection.
This paper presents the results of the followed approach, as well as some practical considerations related to lessons learned
Intern experience at CH���M Hill, Inc.: an internship report
No full textIncludes author's vita"Submitted to the College of Engineering of Texas A&M University in partial
fulfillment of the requirement for the degree of Doctor of Engineering."Includes bibliographical referencesA review of the author's internship experience with CH���M HILL, Inc.
during the period September 1975 through May 1976 is presented. During this nine month
internship the author worked as an Engineer II in the Industrial Processes discipline of this
large consulting engineering firm... The author's prime responsibility was as one of three
lead design engineers on the design of a large wastewater treatment facility for a pulp mill
in Hoquiam, Washington owned by ITT Rayonier Inc. The work generally consisted of the design
of individual treatment units and associated piping and pumping. The purpose of the project
was to provide wastewater treatment capabilities that would satisfy the effluent limitations
(standards) imposed upon the mill by the State of Washington Department of Ecology and the
U.S. Environmental Protection Agency. The author's assignment also entailed necessary
interaction with the project manager and other CH���M HILL design engineers and support staff
members, the client's representatives, and representatives of two other consulting engineering
firms working on the project. Thus, the internship position at CH���M HILL provided considerable
experience coordinating the author's work with the work of other engineers, guiding the design
and administrative efforts of a support staff, and interacting regularly with the client and
other consulting firms. This broad exposure to a variety of engineering and organizational
problems provided a valuable educational experience
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