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Applied and Environmental Microbiology Jun 2022Dehalococcoides mccartyi strains harboring vinyl chloride (VC) reductive dehalogenase (RDase) genes are keystone bacteria for VC detoxification in groundwater aquifers,...
Dehalococcoides mccartyi strains harboring vinyl chloride (VC) reductive dehalogenase (RDase) genes are keystone bacteria for VC detoxification in groundwater aquifers, and bioremediation monitoring regimens focus on D. mccartyi biomarkers. We isolated a novel anaerobic bacterium, " Dehalogenimonas etheniformans" strain GP, capable of respiratory dechlorination of VC to ethene. This bacterium couples formate and hydrogen (H) oxidation to the reduction of trichloro-ethene (TCE), all dichloroethene (DCE) isomers, and VC with acetate as the carbon source. Cultures that received formate and H consumed the two electron donors concomitantly at similar rates. A 16S rRNA gene-targeted quantitative PCR (qPCR) assay measured growth yields of (1.2 ± 0.2) × 10 and (1.9 ± 0.2) × 10 cells per μmol of VC dechlorinated in cultures with H or formate as electron donor, respectively. About 1.5-fold higher cell numbers were measured with qPCR targeting , a single-copy gene encoding a putative VC RDase. A VC dechlorination rate of 215 ± 40 μmol L day was measured at 30°C, with about 25% of this activity occurring at 15°C. Increasing NaCl concentrations progressively impacted VC dechlorination rates, and dechlorination ceased at 15 g NaCl L. During growth with TCE, all DCE isomers were intermediates. Tetrachloroethene was not dechlorinated and inhibited dechlorination of other chlorinated ethenes. Carbon monoxide formed and accumulated as a metabolic by-product in dechlorinating cultures and impacted reductive dechlorination activity. The isolation of a new species able to effectively dechlorinate toxic chlorinated ethenes to benign ethene expands our understanding of the reductive dechlorination process, with implications for bioremediation and environmental monitoring. Chlorinated ethenes are risk drivers at many contaminated sites, and current bioremediation efforts focus on organohalide-respiring Dehalococcoides mccartyi strains to achieve detoxification. We isolated and characterized the first non- bacterium, " Dehalogenimonas etheniformans" strain GP, capable of metabolic reductive dechlorination of TCE, all DCE isomers, and VC to environmentally benign ethene. In addition to hydrogen, the new isolate utilizes formate as electron donor for reductive dechlorination, providing opportunities for more effective electron donor delivery to the contaminated subsurface. The discovery that a broader microbial diversity can achieve detoxification of toxic chlorinated ethenes in anoxic aquifers illustrates the potential of naturally occurring microbes for biotechnological applications.
Topics: Bacteria; Base Composition; Biodegradation, Environmental; Chloroflexi; Dehalococcoides; Ethylenes; Formates; Hydrogen; Phylogeny; RNA, Ribosomal, 16S; Sequence Analysis, DNA; Sodium Chloride; Trichloroethylene; Vinyl Chloride
PubMed: 35674428
DOI: 10.1128/aem.00443-22 -
Angewandte Chemie (International Ed. in... Nov 2021The use of ethane as a platform molecule for the manufacture of polyvinyl chloride (PVC) is a longstanding challenge, which would allow to reduce the raw material costs...
The use of ethane as a platform molecule for the manufacture of polyvinyl chloride (PVC) is a longstanding challenge, which would allow to reduce the raw material costs and CO emissions to produce this plastic. Herein, we discover that rare earth oxychlorides catalyze in a selective (up to 90 %) and stable (>50 h on stream) manner the reaction of ethane and molecular chlorine into 1,2-dichloroethane, which, upon established cracking, will translate into an order of magnitude higher vinyl chloride productivity compared to ethane oxychlorination technologies. In addition, representative europium oxychloride was supported on suitable carriers and was demonstrated to be selective (up to 90 %) and stable (>40 h on stream) in extrudate form. These findings bring the ethane-based production of PVC one step closer to implementation.
PubMed: 34288317
DOI: 10.1002/anie.202105851 -
Environmental Technology Apr 2022It is urgent to develop a high-efficient process for recycling the spent mercuric chlorides catalyst (SMC) from vinyl chloride monomer (VCM) production with the...
It is urgent to develop a high-efficient process for recycling the spent mercuric chlorides catalyst (SMC) from vinyl chloride monomer (VCM) production with the implementation of the 'Minamata Convention on mercury'. A ultrasound and microwave-assisted technology were developed to treat SMC in this study. Firstly, organic carbon deposition was separated from SMC by pretreatment (ultrasonic-assisted ethanol extraction). The optimized extraction conditions were: ultrasonic time 2 h, ultrasonic power 700 W, extraction temperature 65°C, and liquid-solid ratio 7:1. Under these conditions, 90% of hazardous Cl-containing organics were separated from SMC. Then the pretreated SMC was treated by microwave heating for mercury removal. Residual mercury concentration of SMC decreased from original 1.33% to only 11.92 mg/kg at the preferred conditions of 500°C for 60 min and the treated SMC passed the Toxicity Characteristics Leaching Procedure (TCLP) test. Simultaneously, catalyst support activated carbon (AC) was regenerated with specific surface area increasing from original 263.85 to 627.5 m/g. The organics from macropores and surface of AC was removed by pretreatment, intensifying the subsequent Hg removal and regeneration of AC as revealed by the comparative studies. Finally, SMC was subjected to water leaching for recovering metal values. 88.7% of Ba and 95.3% of Ce were leached with ultrasonic power 500 W and ultrasonic time 120 min. SMC was detoxified and valuable components Hg, AC, Ba, Ce were recovered by this new process, which may provide a new idea for industrial treatment of SMC.
Topics: Catalysis; Mercuric Chloride; Metals; Microwaves; Recycling
PubMed: 33001744
DOI: 10.1080/09593330.2020.1831618 -
Environmental Science & Technology Jan 2023Chlorinated organic chemicals are produced and used extensively worldwide, and their risks to the biology and environment are of increasing concern. However, chlorinated...
Chlorinated organic chemicals are produced and used extensively worldwide, and their risks to the biology and environment are of increasing concern. However, chlorinated byproducts [e.g., polychlorinated dibenzo--dioxins and dibenzofurans (PCDD/Fs)] formed during the commercial manufacturing processes and present in organochlorine products are rarely reported. The knowledge on the occurrences and fate of unintentional persistent organic chemicals in the manufacturing of organochlorine chemical is necessary for accurate assessment of the risks of commercial chemicals and their production. Here, PCDD/Fs were tracked throughout chlorobenzene and chloroethylene production processes (from raw materials to final products) by target analysis. Other byproducts that can further transform into PCDD/Fs were also identified by performing non-target screening. As a result, the PCDD/F concentrations were mostly the highest in bottom residues, and the octachlorinated congeners were dominant. Alkali/water washing stages may cause the formation of oxygen-containing byproducts including PCDD/Fs and acyl-containing compounds, so more attention should be paid to these stages. PCDD/Fs were of 0.17 and 0.21-1.2 ng/mL in monochlorobenzene and chloroethylene products, respectively. Annual PCDD/F emissions (17 g toxic equivalent in 2018) during chlorobenzene and chloroethylene production were estimated using PCDD/F emission factors. The results can contribute to the improvement of PCDD/F inventories for the analyzed commercial chemicals.
Topics: Dibenzofurans; Polychlorinated Dibenzodioxins; Vinyl Chloride; Dibenzofurans, Polychlorinated; Environmental Monitoring; Chlorobenzenes
PubMed: 36681930
DOI: 10.1021/acs.est.2c07322 -
Nature Chemistry Feb 2023New approaches are needed to both reduce and reuse plastic waste. In this context, poly(vinyl chloride) (PVC) is an appealing target as it is the least recycled...
New approaches are needed to both reduce and reuse plastic waste. In this context, poly(vinyl chloride) (PVC) is an appealing target as it is the least recycled high-production-volume polymer due to its facile release of plasticizers and corrosive HCl gas. Herein, these limitations become advantageous in a paired-electrolysis reaction in which HCl is intentionally generated from PVC to chlorinate arenes in an air- and moisture-tolerant process that is mediated by the plasticizer. The reaction proceeds efficiently with other plastic waste present and a commercial plasticized PVC product (laboratory tubing) can be used directly. A simplified life-cycle assessment reveals that using PVC waste as the chlorine source in the paired-electrolysis reaction has a lower global warming potential than HCl. Overall, this method should inspire other strategies for repurposing waste PVC and related polymers using electrosynthetic reactions, including those that take advantage of existing polymer additives.
PubMed: 36376389
DOI: 10.1038/s41557-022-01078-w -
Polymers Feb 2021Poly(vinyl chloride) (PVC) undergoes photodegradation induced by ultraviolet (UV) irradiation; therefore, for outdoor applications, its photostability should be enhanced...
Poly(vinyl chloride) (PVC) undergoes photodegradation induced by ultraviolet (UV) irradiation; therefore, for outdoor applications, its photostability should be enhanced through the use of additives. Several carvedilol tin complexes were synthesized, characterized and mixed with PVC to produce thin films. These films were irradiated at 25 °C with a UV light (λ = 313 nm) for up to 300 h. The reduction in weight and changes in chemical structure and surface morphology of the PVC films were monitored. The films containing synthesized complexes showed less undesirable changes than the pure PVC film. Organotin with a high content of aromatics was particularly efficient in inhibiting photodegradation of PVC. The carvedilol tin complexes both absorbed UV light and scavenged radicals, hydrochloride, and peroxides and, therefore, photostabilized PVC.
PubMed: 33561971
DOI: 10.3390/polym13040500 -
Cancers Dec 2021Malignant vascular tumors of the head and neck are rare neoplasms with variable clinical presentation, wide age distribution, and variable clinical courses. The... (Review)
Review
Malignant vascular tumors of the head and neck are rare neoplasms with variable clinical presentation, wide age distribution, and variable clinical courses. The heterogeneous presentation of angiosarcomas and epithelioid hemangioendothelioma often leads to misdiagnosis and unsuitable treatment. While risk factors for angiosarcomas are previous radiation, chronic lymphedema, and exposure to arsenic, thorium oxide, or vinyl chloride, there are only limited and retrospective data available on prognostic factors in EHE. In both angiosarcomas and EHE, surgery is the mainstay of treatment. There is limited evidence regarding the role of radiotherapy in EHE, although EHE is considered relatively radiosensitive. In angiosarcomas, adjuvant radiotherapy is recommended according to retrospective case series. A standard medical therapy for metastasized malignant vascular tumors is lacking. Chemotherapy, which is effective in angiosarcoma, is mostly ineffective in EHE. Targeted therapy, antiangiogenetic drugs and immunotherapy have been studied as new treatment options. The goal of this review is to summarize the current data regarding malignant vascular tumors along with their diagnosis and management.
PubMed: 34944821
DOI: 10.3390/cancers13246201 -
Frontiers in Chemistry 2023Poly (vinyl chloride) (PVC) is commonly used to manufacture biomedical devices and hospital components, but it does not present antimicrobial activity enough to prevent...
Poly (vinyl chloride) (PVC) is commonly used to manufacture biomedical devices and hospital components, but it does not present antimicrobial activity enough to prevent biofouling. With the emergence of new microorganisms and viruses, such as Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) that was responsible for the global pandemic caused by Coronavirus Disease 2019 (COVID-19), it is evident the importance of the development of self-disinfectant PVC for hospital environments and medical clinics where infected people remain for a long time. In this contribution, PVC nanocomposites with silver nanoparticles (AgNPs) were prepared in the molten state. AgNPs are well-known as antimicrobial agents suitable for designing antimicrobial polymer nanocomposites. Adding 0.1 to 0.5 wt% AgNPs significantly reduced Young's modulus and ultimate tensile strength of PVC due to the emergence of microstructural defects in the PVC/AgNP nanocomposites, but the impact strength did not change significantly. Furthermore, nanocomposites have a higher yellowness index (YI) and lower optical bandgap values than PVC. The PVC/AgNP nanocomposites present virucidal activity against SARS-CoV-2 (B.1.1.28 strain) within 48 h when the AgNP content is at least 0.3 wt%, suitable for manufacturing furniture and hospital equipment with self-disinfectant capacity to avoid secondary routes of COVID-19 contagion.
PubMed: 36993814
DOI: 10.3389/fchem.2023.1083399 -
Environmental Science & Technology Apr 2023Chlorinated paraffins (CPs) are used in many products, including soft poly(vinyl chloride) curtains, which are used in many indoor environments. Health hazards posed by...
Chlorinated paraffins (CPs) are used in many products, including soft poly(vinyl chloride) curtains, which are used in many indoor environments. Health hazards posed by CPs in curtains are poorly understood. Here, chamber tests and an indoor fugacity model were used to predict CP emissions from soft poly(vinyl chloride) curtains, and dermal uptake through direct contact was assessed using surface wipes. Short-chain and medium-chain CPs accounted for 30% by weight of the curtains. Evaporation drives CP migration, like for other semivolatile organic plasticizers, at room temperature. The CP emission rate to air was 7.09 ng/(cm h), and the estimated short-chain and medium-chain CP concentrations were 583 and 95.3 ng/m in indoor air 21.2 and 172 μg/g in dust, respectively. Curtains could be important indoor sources of CPs to dust and air. The calculated total daily CP intakes from air and dust were 165 ng/(kg day) for an adult and 514 ng/(kg day) for a toddler, and an assessment of dermal intake through direct contact indicated that touching just once could increase intake by 274 μg. The results indicated that curtains, which are common in houses, could pose considerable health risks through inhalation of and dermal contact with CPs.
Topics: Inhalation Exposure; Vinyl Chloride; Paraffin; Air Pollution, Indoor; Environmental Monitoring; Hydrocarbons, Chlorinated; Dust; China
PubMed: 36976867
DOI: 10.1021/acs.est.2c07040 -
Toxicology and Industrial Health Jun 2021Vinyl chloride (VC) is a confirmed human carcinogen associated with hepatocellular carcinoma and angiosarcoma. However, the role of microRNAs (miRNAs) in liver cell...
Vinyl chloride (VC) is a confirmed human carcinogen associated with hepatocellular carcinoma and angiosarcoma. However, the role of microRNAs (miRNAs) in liver cell cycle changes under VC exposure remains unclear, which prevents research on the mechanism of VC-induced carcinogenesis. In this study, male rats were injected intraperitoneally with VC (0, 5, 25, and 125 mg/kg body weight) for 6, 8, and 12 weeks. Cell cycle analysis of liver cells, miRNA-222, miRNA-199a, miRNA-195, and miRNA-125b expression in the liver and serum, and target protein expression were performed at different time points. The results showed a higher percentage of hepatocytes in the G1/G0 and S phases at the end of 6 and 12 weeks of VC exposure, respectively. MiRNA-222 expression decreased initially and then increased, whereas miRNA-199a, miRNA-195, and miRNA-125b expression increased initially and then decreased, which corresponded with changes in cell cycle distribution and related target proteins expression (p27, cyclinA, cyclinD1, and CDK6). The corresponding expression levels of miRNAs in serum did not change. Dynamic changes in miR-222, miR-199a, miR-195, and miR-125b induced by VC can lead to cell cycle deregulation by affecting cell cycle-related proteins, and these miRNAs can serve as early biomarkers for malignant transformation caused by VC.
Topics: Animals; Carcinoma, Hepatocellular; Cell Cycle; Gene Expression Profiling; Hepatocytes; Humans; Liver Neoplasms; MicroRNAs; Models, Animal; Rats; Vinyl Chloride
PubMed: 33973497
DOI: 10.1177/07482337211015591