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Chemical Permeation through Disposable Gloves
Published in Robert N. Phalen, Howard I. Maibach, Protective Gloves for Occupational Use, 2023
The need to test the permeation of isocyanates compounds through disposable gloves has arisen from isocyanates being a skin sensitizer and causative agent for allergic contact dermatitis.37–40 Isocyanate compounds are used in several industries beyond the collision repair industry and construction, as well as in many products and applications, e.g., in foams, bed liners, adhesives, insulation, varnishes, and isocyanate paints.41,42Figure 24.3 shows an example of the PPE worn by a worker using an isocyanate. Isocyanates include diisocyanates both in monomer and polymer forms. Monomer diisocyanates include methylenebis (phenyl isocyanate) (MDI), toluene diisocyanate (TDI), and hexamethylene diisocyanate (HDI), followed by less common naphthalene diisocyanate (NDI), methylene bis-cyclohexylisocyanate (HMDI) (hydrogenated MDI), and isophorone diisocyanate (IPDI). Examples of widely used polyisocyanates include HDI biuret and HDI isocyanurate.
Cytochrome P450 Enzymes for the Synthesis of Novel and Known Drugs and Drug Metabolites
Published in Peter Grunwald, Pharmaceutical Biocatalysis, 2019
Sanjana Haque, Yuqing Gong, Sunitha Kodidela, Mohammad A. Rahman, Sabina Ranjit, Santosh Kumar
CYP101A1 (also known as CYPcam) is part of the metabolic pathway of P. putida for hydroxylation of camphor. The engineered CYP101A1 enzymes were often used to enhance catalytic activities of alkanes, such as butane, pentane, hexane, and heptanes (Bell et al., 2002), and produce compounds for the flavor and fragrance industries (Bell et al., 2003). The engineered CYP101A1 was also utilized to produce renewable chemicals from small-chain alkanes, such as alcohols (Xu et al., 2005). A recent report showed that engineered CYP101A1 was able to regio- and stereo-selectively hydroxylate isophorone to (R)-4-hydroxyisophorone, which is a synthetic intermediate for pigments and drug molecules. The F87W/Y96F/L244A/V247L mutant of CYP101A1 (generated by site-directed mutagenesis) can selectively yield 98% of (R)-4-hydroxyisophorone, while the wild-type enzyme mainly produces 7-hydroxyisophorone (Dezvarei et al., 2018b).
Combining a bio-based polymer and a natural antifoulant into an eco-friendly antifouling coating
Published in Biofouling, 2020
Ho Yin Chiang, Jiansen Pan, Chunfeng Ma, Pei-Yuan Qian
Poly(L-lactide) diol (PLA, Mw = 2,000g mol−1) from Daigang Biomaterial (Jinan, China) and 1,4-butanediol (BDO) from Shanghai Aladdin Bio-Chem Technology Co., Ltd (Shanghai, China) were dried at 110°C under reduced pressure for 2h prior to use. Isophorone diisocyanate (IPDI) and dibutyltin dilaurate (DBTDL) from Shanghai Aladdin Bio-Chem Technology Co., Ltd (Shanghai, China) were used as received. Tetrahydrofuran (THF) from Innochem (Beijing) Technology Co., Ltd (Beijing, China) was refluxed over CaH2 and distilled prior to use. Rosin, a naturally occurring resin that mainly consists of abietic acid (C19H29COOH), was obtained from Wuzhou Sun Shine Forestry & Chemicals Co., Ltd (Guangxi, China). Synthesized 5-octylfuran-2(5H)-one (butenolide) with a purity exceeding 99% was purchased from ChemPartner Co., Ltd (Shanghai, China) and used as received. Artificial seawater (ASW) was prepared according to ASTM D1141-98 (2013b). Epoxy panels and polyvinyl chloride (PVC) panels were obtained from local hardware stores in Hong Kong.
Anti-biofilm effect of a butenolide/polymer coating and metatranscriptomic analyses
Published in Biofouling, 2018
Wei Ding, Chunfeng Ma, Weipeng Zhang, Hoyin Chiang, Chunkit Tam, Ying Xu, Guangzhao Zhang, Pei-Yuan Qian
Butenolide was synthesized by Shanghai Medicilon Inc. (Shanghai, China). The structure is shown in Figure 1. DCOIT was obtained from The Dow Chemical Company (Midland, MI, USA). The molar masses and dispersity of the poly (ε-caprolactone)-based polyurethane used in the present study were 27,000 and 1.87, respectively. Poly (ε-caprolactone)-based polyurethane was prepared by polyaddition according to the steps described in a previous study (Ma et al. 2013), and a general experimental procedure was as follows: first, isophorone diisocyanate was allowed to react with poly (ε-caprolactone) diol at 70°C for 1 h in tetrahydrofuran under a nitrogen atmosphere, yielding a prepolymer. Subsequently, 1,4-butanediol and dibutyltin dilaurate (DBTDL) were added as the chain extender and catalyst, respectively, and the mixture was allowed to react at 80°C for 3 h. The product was precipitated into hexane twice, filtered, and dried under vacuum at 40°C for 24 h.
Fluorescent melamine-formaldehyde/polyamine coatings for microcapsules enabling their tracking in composites
Published in Journal of Microencapsulation, 2022
Christian Neumann, Sophia Rosencrantz, Andreas Schmohl, Latnikova Alexandra
The isophorone diamine, diethylene triamine, and tris(2-amioethyl)amines were also reacted with the MF at the ratio of (1:0.5). Optical microscopy shows successful deposition on the glass beads surface for all MF/polyamine polymers. Also in TGA, the MF/isophorone diamine (1:0.5), MF/diethylene triamine (1:0.5), and MF/tris(2-amioethyl)amine (1:0.5) showed lower thermal stability than MF, indicating the successful polymerisation. It can be assumed that many more amines will react with the MF and can be deposited as coatings on glass beads or microcapsules.