1,720,959 research outputs found
BPA Adsorption on Microplastics in Different Chemical Conditions
No full textMicroplastics are increasingly seen as a health and environmental issue, both for their direct effects when ingested by living organisms and for their ability to adsorb and concentrate other pollutants. Current water treatment processes do not adequately remove microplastics from municipal water supplies, so a thorough understanding of how microplastics affect water quality is needed. The objective of this study is to evaluate the effects of certain water quality parameters on the ability of polystyrene microplastics to adsorb Bisphenol A (BPA). BPA is an endocrine disruptor used in plastics including food containers, baby bottles, plastic water bottles, and more. BPA can have negative effects on people due to it mimicking estrogen which may influence fertility issues, disrupt hormone systems, and reproduction functions. BPA was chosen because of its ability to adsorb well onto microplastics in comparison to other chemical contaminants found in water. The water quality chemical parameters investigated were chloride, nitrate phosphate, and copper ions. Simulated water samples of chloride were made with three concentrations while nitrate, phosphate, and copper were made with one concentration. Concentrations of each solute were selected based upon Environmental Protection Agency (EPA) guidelines and previous results obtained from testing Chicago River water samples. A constant amount of polystyrene microplastics and BPA were added to each sample and the mixtures were shaken for 5 days to allow time for the BPA to adsorb. The samples were then filtered and the amount of BPA left in the water was determined by measuring its UV absorbance on a UV-vis spectrophotometer. A decrease in the amount of BPA present in the water indicates that it was adsorbed onto the microplastic surface. Conclusions include comparisons between different concentrations of chloride and comparisons between each ion to identify how they affect BPA adsorption. For the future, investigating how these microplastics with BPA may affect the Chicago River water in the North Shore Channel
Trouble in Soil, Microplastics Decreasing Water Content
No full textUnderstanding the causes and impacts of environmental pollution in regional climate and ecosystems is crucial to predict and mitigate future climate change effects. In particular, microplastic contamination in soils is being increasingly documented, which may have a significant effect on soil respiration and carbon dioxide (CO2) emissions into the atmosphere. Microplastics are small particles of plastic (usually less than 5 mm in length) that come from a variety of sources and often emerge from a combination of commercial product manufacturing (including cosmetics and clothing) and the gradual disintegration of larger plastic items, (plastic bags and bottles). Microplastics found in soils are responsible for the destruction of the soil structure; reduction of infiltration capabilities for rain and irrigation waters; and changes to soil characteristics, such as porosity, pH-value, microbial activities, and soil respiration. In this study, we used a STELLA model to simulate the effects of microplastics on soil properties to determine how much additional CO2 will be emitted from the soil to the atmosphere. STELLA is a program to build models of complex systems by connecting icons to simulate different components and processes and the relationships between them. This provides a transparent model structure where underlying equations are based on user input. We designed a STELLA model that includes two main components: the soil water system (with water movement) and CO2 dynamics in the soil. Our experiments simulate seasonal changes in soil water and CO2 emissions over a 12-month period based on boundary conditions of 30-year averaged monthly temperature and precipitation data from Illinois. We are currently in the process of implementing microplastic pathways into the model to study the direct impacts of microplastics on soil properties and quantify additional CO2 emissions from the soil to the atmosphere. The experiments help us gain a better understanding of how climate controls the balance of water and CO2 in the soil and how excessive plastic use affects environmental and climate processes. Studying these relationships will help us determine if and how microplastics affect the amount of CO2 emissions into the atmosphere and whether microplastics play a crucial role in our changing climate
BPA Adsorption on Microplastics in Different Chemical Conditions
Full text linkMicroplastics (plastic particles \u3c 5 mm in size) are increasingly seen as a health and environmental issue, both for their direct effects when ingested by living organisms and for their ability to adsorb and concentrate other pollutants. Current water treatment processes do not adequately remove microplastics from municipal water supplies, so a thorough understanding of how microplastics affect water quality is needed. The objective of this study is to evaluate the effects of certain water quality parameters on the ability of polystyrene microplastics (PS MPs) to adsorb Bisphenol A (BPA). BPA is an endocrine disruptor (chemically like estrogen) used in plastics which can be released into the environment and act as a water pollutant. Water quality chemical parameters investigated were chloride, nitrate, phosphate, and copper ions. Concentrations of each solute were selected based upon Environmental Protection Agency (EPA) guidelines and previous results obtained from testing Chicago River water samples. A constant amount of PS MPs and BPA were added to each sample and the mixtures were shaken for 5 days to allow time for the BPA to adsorb. The samples were then filtered and the amount of BPA left in the water was determined by measuring its UV absorbance on a UV-vis spectrophotometer. BPA concentrations decreased in the water indicating that it had been adsorbed onto the microplastic surface, with the highest adsorption present with copper, which reduced BPA concentrations from 6.7 mg/L to 3.9 mg/L. Statistical analyses showed differences between copper, phosphate, nitrate, and chloride (df = 9, p = 0.002). Future work can apply these results to investigate the implications of pollutant transportation in urban waterways like the Chicago River
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Variations on the Author
Full text link“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Appropriate Similarity Measures for Author Cocitation Analysis
Full text linkWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
Dispelling the Myths Behind First-author Citation Counts
Full text linkWe 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
koamabayili/VECTRON-author-checklist: VECTRON author checklist
No full textWe have done our best to complete the author checklist relating to the use of animals in the hut study. Note that the objective for the hut study was to evaluate the IRS treatment applications for residual efficacy against Anopheles mosquitoes, including the local An. coluzzii mosquito population. Cows were only used to attract mosquitoes into the huts and no tests were carried out directly on the cows. The author checklist is intended for use with studies where experiments are carried out on animals, which is why we have had such difficulty in completing this for the hut study, as many of the questions do not relate to how the cows were used
- …
