Light-based processing of thermosets has gained increasing attention because of its broad application field including its use in digital light processing (DLP) 3D printing. This technique offers efficient design and fabrication of complex structures but typically results in non-recyclable thermoset-based products. To address this issue, we describe here a photocurable, dynamic β-amino ester (BAE) based cross-linker that is not only suitable for DLP printing but can also be chemically degraded transesterification upon the addition of 2-hydroxyethyl methacrylate (HEMA) as a decross-linker.
View Article and Find Full Text PDFPhys Chem Chem Phys
November 2023
This study provides a detailed understanding of how the reaction between CHNH, one of the primary products of the CHNH + OH/Cl reactions, and NO occurs in the atmosphere since the reaction is expected to be a dominant sink for the tropospheric CHNH radical. First, we focus on the reaction of the aminyl radical CHNH with NO, complementing the known reaction between CHNH and NO, to provide the overall picture of the CHNH + NO system. The reaction was meticulously examined across the extended range of temperature (298-2000 K) and pressure (0.
View Article and Find Full Text PDFSteady increase in electricity generation and heavy reliance on coal in Mainland Southeast Asia (M-SEA) create huge pressure on the environment. This study used information collected from individual thermal power plants (TPPs) in M-SEA to calculate emissions of air pollutants and greenhouse gases (GHG) for 2010, 2015 and 2019. The emissions were projected to 2030 following the latest national Power Development Plans.
View Article and Find Full Text PDFHymexazol is a volatile fungicide widely used in agriculture, causing its abundance in the atmosphere; thus, its atmospheric fate and conversion are of great importance when assessing its environmental impacts. Herein, we report a theoretical kinetic mechanism for the oxidation of hymexazol by OH radicals, as well as the subsequent reactions of its main products with O and then with NO by using the Rice-Ramsperger-Kassel-Marcus-based Master equation kinetic model on the potential energy surface explored at the ROCBS-QB3//M06-2X/aug-cc-pVTZ level. The predicted total rate constants (, ) for the reaction between hymexazol and OH radicals show excellent agreement with scarcely available experimental values (e.
View Article and Find Full Text PDFThe widespread use of vinyl butyrate (CHCHOC(O)CHCHCH or VB) in the polymer industry and daily-life materials inevitably results in its emission into the atmosphere. Therefore, understanding the mechanism and kinetics of the VB conversion is critical for evaluating its fate and environmental impacts. Herein, we theoretically investigate the chemical transformation of VB initiated by OH radicals in the atmosphere using the stochastic Rice-Ramsperger-Kassel-Marcus (RRKM)-based master equation kinetic model on the potential energy surface explored at the M06-2X/aug-cc-pVTZ level of theory.
View Article and Find Full Text PDFIn this study, cellulose nanocrystals were prepared the hydrolysis of corncob (CC) biomass using Brønsted acid ionic liquid 1-butyl-3-methylimidazolium hydrogen sulfate [Bmim][HSO]. The corncob was subjected to alkaline pretreatment, and was then hydrolysed by [Bmim][HSO], which acted as both solvent and catalyst. The effects of process conditions, including mass percent of CC (1.
View Article and Find Full Text PDFRecent research has shown writing strategies to have a substantial impact on language learners' writing performance but little is known about what strategies EFL learners use and how they use them in writing academic texts such as reports, final assignments, and project papers. The study reported in this paper extends this line of research by investigating the strategies Vietnamese EFL pre-service teachers use in academic writing. Data included document analysis of 17 pre-service teachers' final assignment papers (one paper per teacher) and individual semi-structured interviews with ten teachers.
View Article and Find Full Text PDFA series of Zr-sulfonic-based metal-organic frameworks have been synthesized by the solvothermal method, namely VNU-17 and VNU-23. Particularly, VNU-17 and VNU-23 adopt the sulfonate group (SO ) moieties densely packed within their structure, which can efficiently uptake MB from wastewater. The maximum adsorption capacity for MB onto VNU-23 is up to 1992 mg g at pH = 7, which is more than five times that of activated carbon and possesses the highest value among all the reported MOF materials.
View Article and Find Full Text PDFMolecularly imprinted polymers (MIPs) have evolved as promising platforms for specific recognition of proteins. However, molecular imprinting of the whole protein molecule is complicated by its large size, conformational instability, and structural complexity. These inherent limitations can be overcome by using epitope imprinting.
View Article and Find Full Text PDFRecent studies have sought to describe and understand English as a second/foreign language (ESL/EFL) teachers' pronunciation teaching practices in different contexts, but much less research has examined how teachers and learners perceive pronunciation instruction at tertiary level, especially in EFL settings. The qualitative study reported in this paper extends this line of research by investigating the beliefs of teachers and learners with regard to pronunciation instruction in tertiary EFL education in Vietnam. Data were collected from individual semi-structured interviews with six EFL teachers and focus group interviews with 24 students (four students per group) at a Vietnamese university.
View Article and Find Full Text PDFOral corrective feedback, a key topic in second language pedagogy and research in applied linguistics and second language acquisition, has widely been investigated for the past two decades. However, the relationship between teachers' and students' beliefs about oral corrective feedback has been relatively underexplored. The current study extends this line of research by examining the extent to which Vietnamese English as a foreign language teachers' and students' beliefs concerning the importance, types, and timing of feedback are aligned.
View Article and Find Full Text PDFIn this study, drying kinetics and quality of purple-fleshed sweet potato (PFSP) subjected to microwave-vacuum drying were investigated. The effects of hot water and steam blanching pretreatment on physicochemical characteristics of the dried products were also considered. The samples were dehydrated in a custom-made microwave-vacuum system at different power levels including 450, 600 and 850 W.
View Article and Find Full Text PDFRecent decades have witnessed extensive research focusing on oral corrective feedback (CF), a key aspect of English as a second/foreign language (ESL/EFL) learning and teaching, but relatively little research has examined the relationship between learner and teacher beliefs about CF. The study reported in this article investigated the relationship between teacher and learner beliefs regarding the optimal targets and sources of CF in Vietnamese secondary EFL contexts. Data which were collected at four Vietnamese public high schools included questionnaires completed by 250 students, interviews with 15 of them, and interviews with 24 teachers.
View Article and Find Full Text PDFIncreasing interests in photodynamic treatment (PDT) for food preservation require a holistic method to evaluate and compare different photosensitizer (PS)-light treatments. In this report, the absorbed photons were used as the basis to assess the antimicrobial photodynamic efficacy of two PSs, chlorophyllin sodium magnesium salt (Chl-Mg) and chlorophyllin sodium copper salt (Chl-Cu), under blue and white light against two typical foodborne pathogens, Gram-negative Escherichia coli, and Gram-positive Staphylococcus aureus. The results showed that the phototoxicity of a PS was predominantly decided by the absorbed photons rather than the characteristics of light sources.
View Article and Find Full Text PDFBioelectrochemistry
August 2021
A novel, sensitive and selective electrochemical sensor based on epitope-imprinted polydopamine (PDA) was developed for ovalbumin (OVA) detection. Molecularly imprinted polydopamine was synthesized on an AuNP-coated screen-printed carbon electrode (SPCE) via electropolymerization in the presence of OVA IgE-binding epitope as the template. Key process parameters including template concentration, electropolymerization cycle, pH, time required for template removal and rebinding were optimized.
View Article and Find Full Text PDFPhotodynamic treatment (PDT) could be a viable option to decontaminate food or food contact surfaces. Such applications require a rigorous method to assess the efficacy of different photosensitizer-light source systems. It is also essential to determine suitable treatment conditions to achieve desirable microbial inhibition for a given process.
View Article and Find Full Text PDFFrom the methanol extract of the wood of (Anacardiaceae), we had isolated a new secondary metabolite named gedebic acid () and six known compounds (). Their chemical structures were determined by spectroscopic methods as well as comparing with data in the literature. All compounds were tested for -glucosidase inhibitory activity.
View Article and Find Full Text PDFThe objective of this study was to develop a simple, inexpensive prototype device for rapid detection of hepatitis B virus (HBV). The device was able to simultaneously amplify, detect and quantify the target HBV DNA. The system was fabricated from a custom-made electrochemical set-up of which the temperature was thermostatically controlled by a water bath.
View Article and Find Full Text PDFThe aim of this work was to develop a programmable flow system for rapid assessment of total antioxidant capacity (TAC). Novel features of the prototype include a single pressure-driven source, versatile manipulation of fluid flows, ability to adapt to different TAC assays, and compatibility with microfluidic design. Antioxidant activity was determined by electrochemical measurement of residual 2,2-diphenyl-2-picrylhydrayl hydrate (DPPH•) free radicals in the solution.
View Article and Find Full Text PDFUnlabelled: Microwave and ohmic combination heating was proposed to improve the uniformity of thermal processing of particulate foods. Thermal patterns of a liquid-particle mixture in a small test cell were studied using both experimental and simulation approaches. Carrot cubes (10 mm × 10 mm × 10 mm) and 0.
View Article and Find Full Text PDFNumerous studies have suggested a link between the angiogenic FGF and VEGF signaling pathways; however, the nature of this link has not been established. To evaluate this relationship, we investigated VEGF signaling in ECs with disrupted FGF signaling in vitro and in vivo. ECs lacking FGF signaling became unresponsive to VEGF, caused by downregulation of VEGF receptor 2 (VEGFR2) expression after reduced Vegfr2 enhancer activation.
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