Search results for "Bisphenol"
showing 10 items of 84 documents
Modelling polycarbonate synthesis rates on the example of bulk heteropolyaddition of diphenyl carbonate and bisphenol A diglycidyl ether
2016
This paper investigates the effects of increased reaction mixture viscosity on the kinetics of linear polymer creation in a bulk polyaddition process of diphenyl carbonate and bisphenol A diglycidyl ether. The paper presents a method for solving a system of bulk polyaddition of diphenyl carbonate and bisphenol A diglycidyl ether process balance equations, allowing the determinatiof the process kinetic parameters. Determination of polymerisation reaction kinetic parameters was also made possible by the use of the so-called partial reaction rate constant. Such an approach enabled a significant simplification of the mathematical expressions describing the heteropolyaddition process and provide…
Relationship between endocrine disruptors and obesity with a focus on bisphenol A: a narrative review
2021
International audience; Introduction: Scientific data suggest that early exposure to endocrine-disrupting chemicals (EDCs) affect -repro, -neuro, -metabolic systems, to which are added other notions such as mixtures, window and duration of exposure, trans-generational effects, and epigenetic mechanisms. Methods: In the present narrative review, we studied the relationship between exposure to EDCs with the appearance and development of obesity. Results: Exposure to EDCs like Bisphenol A during the early stages of development has been shown to lead to weight gain and obesity. EDCs can interfere with endocrine signaling, affect adipocytes differentiation and endocrine function and disrupt meta…
Reduction of Polymerization Shrinkage Stress and Marginal Microleakage Using Soft-Start Polymerization
2003
Purpose: This study evaluated the influence of a soft-start light-curing exposure on polymerization shrinkage stress and marginal integrity of adhesive restorations. Materials and Methods: Six resin-based composites (Pertac II, Tetric Ceram, Definite, Surefil, Solitaire, and Visio-Molar) were adhesively bonded to a cylindrical cavity (n = 9 per material/light) in a photoelastic material. Visible light-curing was applied using either the standard polymerization mode (800 mW/cm2 exposure duration 40 s) of the curing light (Elipar TriLight, 3M ESPE) or the exponential mode from the same device (ramp-curing: 150 mW/cm2 to 800 mW/cm2 within the first 15 s of a total curing time of 40 s). Polymer…
Brominated flame retardants and toxic elements in the meat and liver of red deer (Cervus elaphus), wild boar (Sus scrofa), and moose (Alces alces) fr…
2017
In order to evaluate the contamination status of terrestrial biota in Latvia, muscle and liver tissues of red deer (Cervus elaphus), wild boar (Sus scrofa), and moose (Alces alces) were analyzed for the content of polybrominated diphenyl ethers (PBDE), hexabromocyclododecane (HBCD), tetrabromobisphenol A (TBBPA), as well as cadmium and lead. The highest mean concentrations of PBDEs (46.6pgg-1 wet weight (w.w.)), cadmium (0.95mgkg-1 w.w.), and lead (0.22mgkg-1 w.w.) were observed in the tissues of moose, while the wild boar samples contained the highest levels of HBCD, with the mean concentration equal to 264pgg-1 w.w. in muscle tissues. Generally low mean concentrations of TBBPA from 0.52 t…
Biomass-based composite catalysts for catalytic wet peroxide oxidation of bisphenol A:preparation and characterization studies
2019
The wet granulation process was used to prepare new, efficient, and cost-effective granular biomass-based composite catalysts for catalytic wet peroxide oxidation (CWPO) of bisphenol A (BPA). The most stable composite granules was prepared by mixing biomass-based carbon residue (CR) with metakaolin (MK) combined with calcium oxide (CaO) or cement and a solvent (NaOH or KOH). For all the prepared composite granules, the optimized binding agents to carbon ratio was 0.3, the solvent to carbon ratio 1.2, and the agitation rate 1200 rpm. The specific surface area of the prepared catalysts was 152–205 m2/g. The composite granular catalyst (CR + MK + CaO + NaOH) had the most durable and stable str…
Resource or waste? A perspective of plastics degradation in soil with a focus on end-of-life options.
2018
‘Capable-of-being-shaped’ synthetic compounds are prevailing today over horn, bone, leather, wood, stone, metal, glass, or ceramic in products that were previously left to natural materials. Plastic is, in fact, economical, simple, adaptable, and waterproof. Also, it is durable and resilient to natural degradation (although microbial species capable of degrading plastics do exist). In becoming a waste, plastic accumulation adversely affects ecosystems. The majority of plastic debris pollutes waters, accumulating in oceans. And, the behaviour and the quantity of plastic, which has become waste, are rather well documented in the water, in fact. This review collects existing information on pla…
Photoelectrochemical Bisphenol S Sensor Based on ZnO‐Nanoroads Modified by Molecularly Imprinted Polypyrrole
2019
Molecularly imprinted polymers are important tools for the design of sensors and other molecular recognition based analytical systems. In this paper the development of a photoelectrochemical sensor for selective bisphenol determination is reported. The sensor is based on a glass/ZnO/MIP‐Ppy structure consisting of glass modified by a ZnO layer (glass/ZnO), which is functionalized by molecularly imprinted conducting polymer polypyrrole (MIP‐Ppy). The sensitivity of the sensor to bisphenol is in the range of 0.7–12.5 µm. Selectivity tests to other bisphenolic compounds are performed. Some aspects of a photoinduced response mechanism in glass/ZnO/MIP‐Ppy nanostructures are predicte…
Guidelines for alkylphenols estimation as alkylphenol polyethoxylates pollution indicator in wastewater treatment plant effluents
2013
A solid-phase microextraction coupled with a gas chromatography-mass spectrometry method has been developed for the estimation of technical nonylphenol in the presence of other endocrine disruptors, belonging to different chemical families. The profile of the technical nonylphenol found in real samples was tested, and, given that it was similar to that provided for the standard used, reliable results were obtainable. Endocrine disruptors such as 4-n-nonylphenol, bisphenol A and 4-tert-octylphenol were simultaneously analysed. The best conditions achieved enabled the analysis of all analytes using a sample volume of 15 mL or even only 300 μL. Using such a low sample volume reduced the filtra…
TBBPA causes neurotoxic and the apoptotic responses in cultured mouse hippocampal neurons in vitro
2015
Abstract Background Tetrabromobisphenol A (TBBPA) is a brominated flame retardant widely used in a variety of commercial and household products. TBBPA can become bioaccumulated in human body fluids, and also in different brain regions. The aim of the present study was to determine the viability and apoptosis of cultured mouse hippocampal neurons in vitro after exposure to TBBPA. Additionally, we examined the involvement of ROS generation in the effect of TBBPA. Methods Primary hippocampal neuron cultures were prepared from Swiss mouse embryos on day 17/18 of gestation. The cultures were treated with TBBPA at concentrations ranging from 1 nM to 100 μM for 30 min or 3, 6 or 24 h. To study apo…
Biomonitoring of bisphenols A, F, S and parabens in urine of breastfeeding mothers: Exposure and risk assessment
2019
In the present study we used human biomonitoring to assess the internal exposure and the risk to four parabens and three bisphenols in 103 Spanish breastfeeding mothers participating in the BETTERMIILK project. Urinary methylparaben (MP), ethylparaben (EP), propylparaben (PP) and butylparaben (BP) presented detection frequencies ranging from 12% (BP) to 92% (MP), while bisphenol A (BPA), bisphenol F (BPF) and bisphenol S (BPS) were detected in 76% (BPA) and 20% (BPF, BPS) of the mothers. Average paraben concentrations (geometric mean) ranged from 0.021 ng mL(-1) (BP) to 17.7 ng mL(-1) (MP), whereas bisphenols had geometric means concentrations from 0.042 ng mL(-1) (BPF) to 0.927 ng mL(-1) (…