Objective: The aim of the present study was to determine the chemical species formed inside glass-ionomer cements after fluoride uptake and to investigate the depth of penetration of fluoride ions within the cement matrix.
Methods: An experimental fluoride-free glass with composition 2SiO-AlO-CaO was produced. The glass powder was mixed with aqueous poly(acrylic acid) (PAA), and allowed to set. The resulting specimens were stored in 20ml KF solution with 1000ppm fluorine for 24h and then placed into the same amount of water as for 24h. A fluoride selective electrode was used to give the F concentration of the respective solutions. F MAS-NMR spectra were recorded on powdered cement specimens using a Bruker AVANCE-NEO 600 spectrometer. In addition, SEM observation and EDX chemical analysis were conducted on the cross-section of a carefully fractured specimen.
Results: Fluoride was shown to be mainly present in the surface layers of the specimen after placement in the KF solution, and only a small fraction was re-released into water. F NMR spectroscopy showed that AlF complexes were formed within the cement.
Significance: The fluoride taken up by a free-fluoride glass ionomer cement mostly occupies surface layers and is retained because it bonds to aluminum within the matrix. This finding explains why the majority of fluoride taken up by conventional glass ionomer cements is retained.
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http://dx.doi.org/10.1016/j.dental.2021.04.011 | DOI Listing |
Sci Rep
December 2024
Division of Blood Components and Devices, Center for Biologics Evaluation and Research, FDA, Silver Spring, MD, 20993, USA.
Added safety measures coupled with the development and use of pathogen reduction technologies (PRT) significantly reduces the risk of transfusion-transmitted infections (TTIs) from blood products. Current approved PRTs utilize chemical and/or UV-light based inactivation methods. While the effectiveness of these PRTs in reducing pathogens are well documented, these can cause tolerable yet unintended consequences on the quality and efficacy of the transfusion products.
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December 2024
Key Laboratory of Microbial Technology for Industrial Pollution Control of Zhejiang Province, College of Environment, Zhejiang University of Technology, Hangzhou, 310014, People's Republic of China.
Diquat (DQ) is a non-selective, fast-acting herbicide that is extensively used in aquatic systems. DQ has been registered as the substitute for paraquat due to its lower toxicity. However, the widespread presence of DQ in aquatic systems can pose an ecological burden on aquatic organisms.
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December 2024
Center of Excellence in Catalysis and Catalytic Reaction Engineering, Department of Chemical Engineering, Faculty of Engineering, Chulalongkorn University, Bangkok, 10330, Thailand.
Glycerol, a by-product of biodiesel production, could be converted into various value-added products. This work focuses on its dehydrogenation to dihydroxyacetone (DHA), which is mainly used in the cosmetics industry. While several methods have been employed for DHA production, some necessitate catalysts and involve harsh reaction conditions as well as long reaction times.
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December 2024
Germplasm Bank of Wild Species & Yunnan Key Laboratory for Fungal Diversity and Green Development, Kunming Institute of Botany, Chinese Academy of Sciences, Kunming, 650201, China.
Continuous cropping obstacle has been becoming the bottleneck for the stable development of morel cultivation. The allelopathic effect of soil allelochemicals may play an instrumental role in the morel soil sickness. In this study, the allelochemicals were identified by gas chromatography-mass spectrometry (GC-MS) combined with in vitro bioassay.
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December 2024
Winogradsky Institute of Microbiology Federal Research Center Fundamentals of Biotechnology Russian Academy of Sciences, 60 let Oktyabrya Prospect, 7 Build.2, Moscow, Russia.
The Kuril Islands are located in the Far-East of Russia and enriched with shallow and terrestrial hot springs. Prokaryotic diversity of Kuril geothermal environments has been studied fragmentarily and mainly by culture-dependent methods. We performed the first large-scale investigation of microbial communities, inhabited more than 30 terrestrial hot springs of Kunashir and Iturup Islands, analyzed by 16S rRNA gene fragment amplicon sequencing, together with chemical analysis of thermal waters and sediments.
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