271 research outputs found
Current mass spectrometry strategies for the analysis of pesticides and their metabolites in food and water matrices
No full textAnalysis of pesticides and their metabolites in food and water matrices continues to be an active research area closely related to food safety and environmental issues. This review discusses the most widely applied mass spectrometric (MS) approaches to pesticide residues analysis over the last few years. The main techniques for sample preparation remain solvent extraction and solid-phase extraction. The QuEChERS (Quick, Easy, Cheap, Effective, Rugged, Safe) approach is being increasingly used for the development of multi-class pesticide residues methods in various sample matrices. MS detectors—triple quadrupole (QqQ), ion-trap (IT), quadrupole linear ion trap (QqLIT), time-of-flight (TOF), and quadrupole time-of-flight (QqTOF)—have been established as powerful analytical tools sharing a primary role in the detection/quantification and/or identification/confirmation of pesticides and their metabolites. Recent developments in analytical instrumentation have enabled coupling of ultra-performance liquid chromatography (UPLC) and fast gas chromatography (GC) with MS detectors, and faster analysis for a greater number of pesticides. The newly developed “ambient-ionization” MS techniques (e.g., desorption electrospray ionization, DESI, and direct analysis in real time, DART) hyphenated with high-resolution MS platforms without liquid chromatography separation, and sometimes with minimum pre-treatment, have shown potential for pesticide residue screening. The recently introduced Orbitrap mass spectrometers can provide high resolving power and mass accuracy, to tackle complex analytical problems involved in pesticide residue analysi
Policy Formulation: A Dynamic Process
No full textLesley Burrows, Rip Economou, Michael Ippolito's thesis on dynamic policy development in public schools in Connecticut and Rhode Island.This thesis is being archived as a Digitized Shelf Copy for campus access to current students and staff only. We currently cannot provide this open access without the author's permission. If you are the author of this work and desire to provide it open access or wish access removed please contact the Wahlstrom Library to discuss permission
Molecular characterization of the ATPase of type II secretion system in Escherichia coli bacterium
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A Study of the square-wave modulation for the determination of trace metals by anodic and adsorptive stripping voltammetry on bismuth-film electrodes
No full textThis work reports on the application of square-wave stripping voltammetry for the simultaneous determination of trace metals on bismuth-film electrodes (BiFEs). Cd)II), PB(II) and Zn(II) were determined by square-wave anodic stripping voltammetry (SWASV) on an in-situ plated BiFEs while Ni(II) and Co(II) were determined by square-wave adsorptive stripping voltammetry (SWAdSV) on an exsitu plated BiFE. The general characteristics and advantages of the square-wave modulation are presented and discussed in the context of representative voltammograms. The effects of the square-wave parameters (frequency, step increment, pilse height) on the voltammetric signals obtained on BiFEs were studied and discussed in both the cases of SWASV and SWAdSV
Enhanced Retention of Historical Information with Empathetic Pedagogical Conversational Agents (PCAs)
No full textEmbodied learning using extended reality (XR) technology can enhance learning and satisfaction during field trips to historical sites. This study evaluates the impact of Empathetic Pedagogical Conversational Agents (PCAs) on historical information retention within a simulated XR environment. PCAs employ verbal and nonverbal behaviors to attract attention, with variations in humorous versus serious tones. These behaviors can evoke emotions that motivate learning and influence cognitive processes. The study used facial expressions and eye tracking to measure the impact on the retention of historical information, comparing attention-grabbing PCAs (AG-PCA) with non-attention-grabbing PCAs (NAG-PCA). Results show that AG-PCAs triggered curiosity and positive emotions, but also some dislike, leading to better retention of historical information among NAG-PCAs, particularly among female participants. The study concludes with recommendations for designing PCAs and multimodal content to enhance historical information retention and learner satisfaction
Screen-Printed Electrodes Modified with “Green” Metals for Electrochemical Stripping Analysis of Toxic Elements
No full textThis work reviews the field of screen-printed electrodes (SPEs) modified with “green” metals for electrochemical stripping analysis of toxic elements. Electrochemical stripping analysis has been established as a useful trace analysis technique offering many advantages compared to competing optical techniques. Although mercury has been the preferred electrode material for stripping analysis, the toxicity of mercury and the associated legal requirements in its use and disposal have prompted research towards the development of “green” metals as alternative electrode materials. When combined with the screen-printing technology, such environment-friendly metals can lead to disposable sensors for trace metal analysis with excellent operational characteristics. This review focuses on SPEs modified with Au, Bi, Sb, and Sn for stripping analysis of toxic elements. Different modification approaches (electroplating, bulk modification, use of metal precursors, microengineering techniques) are considered and representative applications are described. A developing related field, namely biosensing based on stripping analysis of metallic nanoprobe labels, is also briefly mentioned
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