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1.
BMC Genomics ; 22(1): 420, 2021 Jun 05.
Artigo em Inglês | MEDLINE | ID: mdl-34090348

RESUMO

BACKGROUND: Single-cell RNA sequencing (scRNA-seq) has led to remarkable progress in our understanding of tissue heterogeneity in health and disease. Recently, the need for scRNA-seq sample fixation has emerged in many scenarios, such as when samples need long-term transportation, or when experiments need to be temporally synchronized. Methanol fixation is a simple and gentle method that has been routinely applied in scRNA-sEq. Yet, concerns remain that fixation may result in biases which may change the RNA-seq outcome. RESULTS: We adapted an existing methanol fixation protocol and performed scRNA-seq on both live and methanol fixed cells. Analyses of the results show methanol fixation can faithfully preserve biological related signals, while the discrepancy caused by fixation is subtle and relevant to library construction methods. By grouping transcripts based on their lengths and GC content, we find that transcripts with different features are affected by fixation to different degrees in full-length sequencing data, while the effect is alleviated in Drop-seq result. CONCLUSIONS: Our deep analysis reveals the effects of methanol fixation on sample RNA integrity and elucidates the potential consequences of using fixation in various scRNA-seq experiment designs.


Assuntos
Metanol , RNA , Sequência de Bases , RNA/genética , Análise de Sequência de RNA , Análise de Célula Única
2.
Braz J Med Biol Res ; 54(9): e10700, 2021.
Artigo em Inglês | MEDLINE | ID: mdl-34076141

RESUMO

It was previously demonstrated that the methanol fraction of Sideroxylon obtusifolium (MFSOL) promoted anti-inflammatory and healing activity in excisional wounds. Thus, the present work investigated the healing effects of MFSOL on human keratinocyte cells (HaCaT) and experimental burn model injuries. HaCaT cells were used to study MFSOL's effect on cell migration and proliferation rates. Female Swiss mice were subjected to a second-degree superficial burn protocol and divided into four treatment groups: Vehicle, 1.0% silver sulfadiazine, and 0.5 or 1.0% MFSOL Cream (CrMFSOL). Samples were collected to quantify the inflammatory mediators, and histological analyses were performed after 3, 7, and 14 days. The results showed that MFSOL (50 µg/mL) stimulated HaCaT cells by increasing proliferation and migration rates. Moreover, 0.5% CrMFSOL attenuated myeloperoxidase (MPO) activity and also stimulated the release of interleukin (IL)-1ß and IL-10 after 3 days of treatment. CrMFSOL (0.5%) also enhanced wound contraction, promoted improvement of tissue remodeling, and increased collagen production after 7 days and VEGF release after 14 days. Therefore, MFSOL stimulated human keratinocyte (HaCaT) cells and improved wound healing via modulation of inflammatory mediators of burn injuries.


Assuntos
Queimaduras , Sapotaceae , Queimaduras/tratamento farmacológico , Feminino , Humanos , Queratinócitos , Metanol , Folhas de Planta , Prolina , Cicatrização
3.
Appl Microbiol Biotechnol ; 105(11): 4635-4648, 2021 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-34059939

RESUMO

Currently, the lack of reliable strategies for the diagnosis and treatment of cancer makes the identification and characterization of new therapeutic targets a pressing matter. Several studies have proposed the Six Transmembrane Epithelial Antigen of the Prostate 1 (STEAP1) as a promising therapeutic target for prostate cancer. Although structural and functional studies may provide deeper insights on the role of STEAP1 in cancer, such techniques require high amounts of purified protein through biotechnological processes. Based on the results presented, this work proposes the application, for the first time, of a fed-batch profile to improve STEAP1 biosynthesis in mini-bioreactor Komagataella pastoris X-33 Mut+ methanol-induced cultures, by evaluating three glycerol feeding profiles-constant, exponential, and gradient-during the pre-induction phase. Interestingly, different glycerol feeding profiles produced differently processed STEAP1. This platform was optimized using a combination of chemical chaperones for ensuring the structural stabilization and appropriate processing of the target protein. The supplementation of culture medium with 6 % (v/v) DMSO and 1 M proline onto a gradient glycerol/constant methanol feeding promoted increased biosynthesis levels of STEAP1 and minimized aggregation events. Deglycosylation assays with peptide N-glycosidase F showed that glycerol constant feed is associated with an N-glycosylated pattern of STEAP1. The biological activity of recombinant STEAP1 was also validated, once the protein enhanced the proliferation of LNCaP and PC3 cancer cells, in comparison with non-tumoral cell cultures. This methodology could be a crucial starting point for large-scale production of active and stable conformation of recombinant human STEAP1. Thus, it could open up new strategies to unveil the structural rearrangement of STEAP1 and to better understand the biological role of the protein in cancer onset and progression.


Assuntos
Antígenos de Neoplasias/biossíntese , Glicerol , Metanol , Oxirredutases/biossíntese , Proteínas Recombinantes/biossíntese , Humanos , Pichia , Regiões Promotoras Genéticas , Saccharomycetales
4.
Int J Mol Sci ; 22(11)2021 May 22.
Artigo em Inglês | MEDLINE | ID: mdl-34067304

RESUMO

Methylselenol (MeSeH) is a major cytotoxic metabolite of selenium, causing apoptosis in cancer cells through mechanisms that remain to be fully established. Previously, we demonstrated that, in Saccharomyces cerevisiae, MeSeH toxicity was mediated by its metabolization into selenomethionine by O-acetylhomoserine (OAH)-sulfhydrylase, an enzyme that is absent in higher eukaryotes. In this report, we used a mutant met17 yeast strain, devoid of OAH- sulfhydrylase activity, to identify alternative targets of MeSeH. Exposure to dimethyldiselenide (DMDSe), a direct precursor of MeSeH, caused an endoplasmic reticulum (ER) stress, as evidenced by increased expression of the ER chaperone Kar2p. Mutant strains (∆ire1 and ∆hac1) unable to activate the unfolded protein response were hypersensitive to MeSeH precursors but not to selenomethionine. In contrast, deletion of YAP1 or SKN7, required to activate the oxidative stress response, did not affect cell growth in the presence of DMDSe. ER maturation of newly synthesized carboxypeptidase Y was impaired, indicating that MeSeH/DMDSe caused protein misfolding in the ER. Exposure to DMDSe resulted in induction of the expression of the ER oxidoreductase Ero1p with concomitant reduction of its regulatory disulfide bonds. These results suggest that MeSeH disturbs protein folding in the ER by generating a reductive stress in this compartment.


Assuntos
Estresse do Retículo Endoplasmático/efeitos dos fármacos , Metanol/análogos & derivados , Compostos Organosselênicos/farmacologia , Saccharomyces cerevisiae/efeitos dos fármacos , Retículo Endoplasmático/efeitos dos fármacos , Retículo Endoplasmático/metabolismo , Metanol/farmacologia , Chaperonas Moleculares/metabolismo , Oxirredução/efeitos dos fármacos , Dobramento de Proteína/efeitos dos fármacos , Saccharomyces cerevisiae/metabolismo , Proteínas de Saccharomyces cerevisiae/metabolismo , Resposta a Proteínas não Dobradas/efeitos dos fármacos
5.
J Chromatogr A ; 1650: 462252, 2021 Aug 02.
Artigo em Inglês | MEDLINE | ID: mdl-34087521

RESUMO

The solvation parameter model is used for the selectivity evaluation of siloxane-bonded reversed-phase columns with mobile phases containing from 20-70 % (v/v) acetone-water. System constants determined at 10 % (v/v) increments of acetone solvent were utilized for the construction of system maps and correlation diagrams on five columns with different stationary phase chemistry; superficially porous octadecylsiloxane-bonded silica (Kinetex C18), electrostatic-shielded octadecylsiloxane-bonded silica (Luna Omega PS C18, diisobutyloctadecyl-bonded silica(Kinetex XB-C18), phenylhexyl-bonded silica (Kinetex Phenyl-Hexyl) and octylsiloxane-bonded silica (Kinetex C8). For all columns and acetone-water compositions the calibration n = 34 to 39 had a range for the coefficient of determination from 0.988 to 0.998, Fisher statistic from 277 to 1551 and a standard error of the estimate from 0.024 to 0.097. A comparison of the system constants for acetonitrile and methanol compositions for the same separation conditions confirms that the general solvation properties of acetone mobiles phases are more similar to that of acetonitrile than methanol and that method transfer should not be difficult.


Assuntos
Acetona , Cromatografia de Fase Reversa , Água , Acetona/química , Acetonitrilas/química , Calibragem , Indicadores e Reagentes , Metanol/química , Porosidade , Dióxido de Silício/química , Siloxanas/química , Solventes/química , Água/química
6.
Chemosphere ; 278: 130453, 2021 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-34126685

RESUMO

A method quantifying 16 polycyclic aromatic hydrocarbons (PAHs) in wood vinegars (WVs) obtained from slow pyrolysis of biomass with ultrasonic-assisted liquid-liquid extraction/gas chromatography-mass spectrometry (USALLE/GC-MS) was established. The recovery range was 83-128%, and the relative standard deviations (RSD%) were less than 15% except naphthalene, acenaphthylene and acenaphthene. Acenaphthylene, acenaphthene, fluorene, anthracene, phenanthrene, fluoranthene, and pyrene were observed in all samples and the other 9 compounds, including benzopyrene (B[a]P), were not detected. The concentration of ∑PAHs referred to the sum total of 7 PAHs mentioned above was 22.0-498.3 µg L-1. The PAHs concentration increased with the increasing pyrolysis temperature in bamboo willow WV, pinus sylvestris WV, and corncob WV, while it increased initially, and then decreased with a maximum at 550 °C in rice husk WV. The ∑PAHs concentration increased with a higher heating rate in the white pine WV, while rice husk WV and cornstalk WV showed the opposite trend. The varied condensed aromatic ring number showed that 3-ring PAHs relatively were the main component in all kind WVs. 3-ring PAHs increased with increasing temperatures, while 4-ring PAHs showed an opposite trend in sawdust WV and corncob WVs. A higher cellulose content in sawdust enhanced the reaction of lignin leading to a higher concentration of PAHs than that in straws and leaves. Calculations of the toxicity equivalents of PAHs in WVs indicated that anthracene was the most toxic among the PAHs, and the pinus sylvestris WV had the highest risk of ∑PAHs toxicity in all WVs.


Assuntos
Hidrocarbonetos Policíclicos Aromáticos , Ácido Acético , Biomassa , Metanol , Pirólise , Medição de Risco
7.
Biomed Res Int ; 2021: 6663399, 2021.
Artigo em Inglês | MEDLINE | ID: mdl-33954194

RESUMO

Today, the tendency to use of natural preservatives to increase food security has expanded. In the present study, antibacterial effects of Areca Nut fruit extracts were evaluated against Staphylococcus aureus, Escherichia coli, Salmonella enterica, and Enterobacter aerogenes bacteria using agar disc diffusion technique. Methanol, ethanol, and water were used as solvents for extraction by maceration method, and extracts were analyzed by GC-MS. The antibacterial activity was evaluated using microtiter broth dilution method to determine minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC). Results revealed that all ATCC strains were significantly inhibited by ethanolic and methanolic extracts. Escherichia coli produced a significantly larger zone of inhibition for Gentamicin (35 ± 0.65 mm) and Penicillin (25 mm ± 0.56), while Enterobacter aerogenes produced smaller zone of inhibition for Gentamicin (20 ± 0.87 mm) and Penicillin (15 ± 0.87 mm). Also, methanolic extract had considerable antibacterial activity with MIC value of 1.56 mg/mL against Escherichia coli. All of extracts were used to evaluate antibacterial effects in prepared cake, and as a result, all pathogenies were the most sensitive by methanolic extract in 100 mg/L of concentration except Escherichia coli that were more sensitive by ethanolic extract. In conclusion, the Areca Nut fruit extracts may be used as a natural preservative in food industries. Future studies should focus on the effect of Areca Nut fruit extracts in bakery and drinking industries.


Assuntos
Antibacterianos/farmacologia , Areca/química , Bactérias/efeitos dos fármacos , Etanol/química , Frutas/química , Metanol/química , Extratos Vegetais/farmacologia , Água/química , Cromatografia Gasosa-Espectrometria de Massas , Testes de Sensibilidade Microbiana
8.
J Agric Food Chem ; 69(19): 5481-5490, 2021 May 19.
Artigo em Inglês | MEDLINE | ID: mdl-33955745

RESUMO

A three-liquid-phase system (TLPS) was developed and used as a novel enzymatic one-pot multistep reaction (EOMR) system. In this system, lipase and phospholipase were enriched in a single liquid phase with a high recovery (ca. 98%) and then used for the simultaneous catalysis of mutually inhibiting and interfering reactions (hydrolysis of phospholipids and glyceride in crude oil). A novel emulsion containing the two dispersed droplets (W2/O/W2 and W1/W2 emulsion structures) could be the key reason for this phenomenon because the emulsion system not only provided a new catalytic interface but also relieved the product inhibition. As a result, the content of free fatty acid (main hydrolysate of the glyceride) and the removal of phospholipid from the crude oil could be increased to 96 and 95%, respectively, within 1 h. The product obtained from the EOMR was directly used in the production of biodiesel via enzymatic esterification, and the content of fatty acid methanol ester could be increased to 93% within 2 h. Furthermore, the enzymes in the middle phase could also be reused, at least for eight rounds without significant loss in catalytic efficiency. Therefore, the TLPS could be considered as an ideal catalytic platform for the EOMR.


Assuntos
Biocombustíveis , Lipase , Esterificação , Ácidos Graxos , Lipase/metabolismo , Metanol
9.
J Pharm Biomed Anal ; 201: 114126, 2021 Jul 15.
Artigo em Inglês | MEDLINE | ID: mdl-33989995

RESUMO

RP-18 TLC chromatography was used to evaluate the pharmacokinetic properties (volume of distribution, VD; plasma protein binding, %PPB; the ability to cross the blood-brain barrier expressed as log PS and log BB) of several cosmetic raw materials - sunscreen and preservatives. The majority of these compounds are intended for topical use on skin and their drug-likeness and the ability to cross biological barriers are undesired. The retention parameters RM0, S, PC1 and RM75 % obtained for mobile phases containing six organic modifiers (methanol, acetonitrile, THF, acetone, dioxane, DMF) were used as the sole descriptors or combined with calculated physicochemical properties (PSA, MW, VM) of studied compounds. The chromatographic parameters considered in this study are, generally speaking, good predictors of the compounds' pharmacokinetic properties VD, %PPB and log PS. RM75 % and the novel parameters derived from it (RM75 %/MW and RM75 %/VM) can be considered time- and cost-effective alternatives to the chromatographic parameters obtained by extrapolation or interpolation methods. In the case of some pharmacokinetic properties investigated in this study additional descriptors (PSA) have a significant influence on the quality of correlations.


Assuntos
Preparações Farmacêuticas , Protetores Solares , Cromatografia de Fase Reversa , Cromatografia em Camada Delgada , Metanol
10.
Mar Drugs ; 19(5)2021 Apr 29.
Artigo em Inglês | MEDLINE | ID: mdl-33947091

RESUMO

Antioxidants prevent ageing and are usually quantified and screened using the 1,1-diphenyl-2-picrylhydrazyl (DPPH) assay. However, this assay cannot be used for salt-containing samples, such as the cell-free supernatants of marine microorganisms that are aggregated under these conditions. Herein, the DPPH solvent (methanol or ethanol) and its water content were optimized to enable the analysis of salt-containing samples, aggregation was observed for alcohol contents of >70%. The water content of methanol influenced the activities of standard antioxidants but did not significantly affect that of the samples. Based on solution stability considerations, 70% aqueous methanol was chosen as the optimal DPPH solvent. The developed method was successfully applied to the cell-free supernatants of marine bacteria (Pseudoalteromonas rubra and Pseudoalteromonas xiamenensis), revealing their high antioxidant activities. Furthermore, it was concluded that this method would be useful for the screening of marine microorganism-derived antioxidants, which also has numerous potential applications, such as salt-fermented foods.


Assuntos
Antioxidantes/farmacologia , Compostos de Bifenilo/química , Picratos/química , Pseudoalteromonas/metabolismo , Antioxidantes/isolamento & purificação , Etanol/química , Metanol/química , Solventes/química
11.
J Agric Food Chem ; 69(21): 5882-5886, 2021 Jun 02.
Artigo em Inglês | MEDLINE | ID: mdl-34028273

RESUMO

The diastereoselectivity of adducts in the addition reaction via the Felkin-Anh model is affected significantly by the steric effect of bulky groups. However, the influence of steric alkyl chain length has not been studied for the diastereoselectivity. In this work, we present a new strategy for the racemic synthesis of ß-methyl alcohols to obtain various diastereomer ratios using the Felkin-Anh model. The addition of alkyl Grignard reagents to α-methyl aldehydes afforded diastereomer ratios of threo/erythro ≈ 2:1, while the reduction in structurally related ketones using LiAlH4 afforded ratios of threo/erythro ≈ 1:1. The experimental data showed no effect of alkyl chain length on either side on the stereoselectivity of adducts. All synthesized analogues were evaluated for attractiveness to Rhynchophorus ferrugineus weevils in the field. Five novel derivatives, including two alcohols and three ketones, were found to attract weevils in the field trials. Among them, 3-methyldecan-4-one (5b) and 4-methyldecan-5-ol (11a) were found to be the most attractive to the insects.


Assuntos
Gorgulhos , Álcoois , Animais , Cetonas , Metanol
12.
BMJ Open ; 11(5): e043037, 2021 05 19.
Artigo em Inglês | MEDLINE | ID: mdl-34011582

RESUMO

OBJECTIVES: To fill the existing research gap related to long-term costs of postacute care in methanol poisoning survivors, healthcare cost for 6 years after the outbreak has been modelled and estimated. DESIGN: In a prospective longitudinal cohort study, data collected from 55 survivors of the Czech methanol mass poisoning outbreak in 2012 were collected in four rounds (5 months, then 2, 4 and 6 years after the discharge) in the General University Hospital in Prague according to the same predefined study protocol. The collected data were used to inform the cost model. SETTING AND PARTICIPANTS: All 83 patients discharged from a hospital poisoning treatment after the 2012 methanol outbreak were informed about the study and invited to participate. Fifty-five patients (66%) gave their written informed consent and were followed until their death or the last follow-up 6 years later. The costs were modelled from the Czech healthcare service (general health insurance) perspective. MAIN OUTCOME MEASURES: Long-term national budget impact of the methanol poisoning outbreak, frequencies of sequelae and their average costs. RESULTS: The postacute cost analysis concentrated on visual and neurological sequelae that were shown to be dominant. Collected data were used to create process maps portraying gradual changes in long-term sequelae over time. Individual process maps were created for the central nervous system, peripheral nervous system, sequelae detected during eye examinations and sequelae concerning the visual evoked potentials. Based on the process maps the costs of the postacute outpatient care were estimated. CONCLUSIONS: In 2013-2019 the highest costs per patient related to postacute care were found in the first year; the average costs decreased afterwards, and remained almost constant for the rest of the studied period of time. These costs per patient ranged from CZK4142 in 2013 to CZK1845 in 2018, when they raised to CZK2519 in 2019 again.


Assuntos
Metanol , Envenenamento , Surtos de Doenças , Potenciais Evocados Visuais , Custos de Cuidados de Saúde , Humanos , Estudos Longitudinais , Envenenamento/epidemiologia , Estudos Prospectivos , Cuidados Semi-Intensivos , Sobreviventes
13.
J Chromatogr A ; 1649: 462230, 2021 Jul 19.
Artigo em Inglês | MEDLINE | ID: mdl-34038786

RESUMO

This paper reports on a new method for simultaneously determining the amphiphobicities of material surface by a dual-indicator assisted headspace gas chromatography. After adding 40 µL of both methanol-water and toluene-oil droplets on the sample surface for 20 s, the sample was turned vertically (to remove water and oil) and then placed in a headspace vial. The amount of methanol and toluene in the residual water and oil adhered to material surface was quantified using headspace gas chromatography. The results showed that the method has good measurement precision (RSD < 4.58%). It can be an effective tool for simultaneously determining the amphiphobicities of material surface.


Assuntos
Cromatografia Gasosa/métodos , Metanol/análise , Propriedades de Superfície , Tolueno/análise , Volatilização , Água/química
14.
J Environ Manage ; 289: 112468, 2021 Jul 01.
Artigo em Inglês | MEDLINE | ID: mdl-33823414

RESUMO

A continuous increase in the amount of greenhouse gases (GHGs) is causing serious threats to the environment and life on the earth, and CO2 is one of the major candidates. Reducing the excess CO2 by converting into industrial products could be beneficial for the environment and also boost up industrial growth. In particular, the conversion of CO2 into methanol is very beneficial as it is cheaper to produce from biomass, less inflammable, and advantageous to many industries. Application of various plants, algae, and microbial enzymes to recycle the CO2 and using these enzymes separately along with CO2-phillic materials and chemicals can be a sustainable solution to reduce the global carbon footprint. Materials such as MOFs, porphyrins, and nanomaterials are also used widely for CO2 absorption and conversion into methanol. Thus, a combination of enzymes and materials which convert the CO2 into methanol could energize the CO2 utilization. The CO2 to methanol conversion utilizes carbon better than the conventional syngas and the reaction yields fewer by-products. The methanol produced can further be utilized as a clean-burning fuel, in pharmaceuticals, automobiles and as a general solvent in various industries etc. This makes methanol an ideal fuel in comparison to the conventional petroleum-based ones and it is advantageous for a safer and cleaner environment. In this review article, various aspects of the circular economy with the present scenario of environmental crisis will also be considered for large-scale sustainable biorefinery of methanol production from atmospheric CO2.


Assuntos
Dióxido de Carbono , Metanol , Biomassa , Carbono , Catálise
15.
J Chromatogr A ; 1644: 462121, 2021 May 10.
Artigo em Inglês | MEDLINE | ID: mdl-33845425

RESUMO

In this study, we present results obtained on the enantioseparation of some cationic compounds of pharmaceutical relevance, namely tetrahydro-ß-carboline and 1,2,3,4-tetrahydroisoquinoline analogs. In high-performance liquid chromatography, chiral stationary phases (CSPs) based on strong cation exchanger were employed using mixtures of methanol and acetonitrile or tetrahydrofuran as mobile phase systems with organic salt additives. Through the variation of the applied chromatographic conditions, the focus has been placed on the study of retention and enantioselectivity characteristics as well as elution order. Retention behavior of the studied analytes could be described by the stoichiometric displacement model related to the counter-ion effect of ammonium salts as mobile phase additives. For the thermodynamic characterization parameters, such as changes in standard enthalpy Δ(ΔH°), entropy Δ(ΔS°), and free energy Δ(ΔG°), were calculated on the basis of van't Hoff plots derived from the ln α vs. 1/T curves. In all cases, enthalpy-driven enantioseparations were observed with a slight, but consistent dependence of the calculated thermodynamic parameters on the eluent composition. Elution sequences of the studied compounds were determined in all cases. They were found to be opposite on the enantiomeric stationary phases and they were not affected by either the temperature or the eluent composition.


Assuntos
Carbolinas/química , Cromatografia Líquida de Alta Pressão/métodos , Resinas de Troca Iônica/química , Tetra-Hidroisoquinolinas/química , Acetonitrilas , Cátions , Metanol , Estereoisomerismo , Relação Estrutura-Atividade , Temperatura
16.
Bioresour Technol ; 332: 125141, 2021 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-33862384

RESUMO

This study presents predictive modelling with uncertainty analysis, optimization and techno-economic feasibility of Bio-catalyzed Biodiesel Production from Azidirica Indica Oil (BCBPAIO). Central Composite Design (CCD) predictive model and optimum conditions for BCBPAIO were developed in Design Expert software. The model uncertainty analysis was performed using Monte Carlo simulation. The BCBPAIO simulation and economic analysis were conducted in ASPEN Batch Process Developer V10. The correlation coefficient (R2) and adjusted R2 value of the CCD model were 0.9922 and 0.9780 respectively. CCD model certainty gave 73.51% with 100,000 trials; the oil transesterification optimum conditions gave 87.04% conversion with 3.62 wt% of catalysts; and methanol to oil molar ratio of 8:1 at 59 °C for 4 h. The annual production cost, total capital investment, payback time and internal rate of returns are $ 3537105, $ 5243784, 2.67 and 43% respectively. This study shows that the production is profitably feasible.


Assuntos
Biocombustíveis , Metanol , Catálise , Esterificação , Óleos Vegetais , Incerteza
17.
Water Res ; 197: 117077, 2021 Jun 01.
Artigo em Inglês | MEDLINE | ID: mdl-33812128

RESUMO

Bioconversion of biogas to value-added liquids has received increasing attention over the years. However, many biological processes are restricted under acidic conditions owing to the excessive carbon dioxide (CO2, 30-40% v/v) in biogas. Here, using an enriched culture dominated by acid-tolerant ammonia-oxidizing bacteria (AOB) 'Candidatus Nitrosoglobus', this study examined the feasibility of producing methanol from methane in the CO2-acidified environment (i.e. pH of 5.0). Within the tested dissolved methane range (0.1-0.9 mM), methane oxidation by the acid-tolerant AOB culture followed first-order kinetics, with the same rate constant (i.e. 0.43 (L/(g VSS‧h)) between pH 7.0 and 5.0. The acidic methane oxidation showed robustness against high dissolved concentrations of CO2 (up to 4.06 mM) and hydrogen sulfide (H2S up to 0.11 mM), which led to a high methanol yield of about 30-40%. As such, the raw biogas containing toxic CO2 and H2S can directly serve for methanol production by this acid-tolerant AOB culture, economizing a conventionally costly biogas upgradation process. Afterwards, two batch reactors fed with methane and oxygen intermittently both obtained a final concentration of 1.5 mM CH3OH (equal to 72 mg chemical oxygen demand/L) in the liquid, suggesting it is a useful carbon source to enhance denitrification in wastewater treatment systems. In addition, ammonia availability was identified to be critical for a higher rate of this AOB-mediated methanol production. Overall, our results for the first time demonstrated the capability of a novel acid-tolerant AOB culture to oxidize methane, and also illustrated the technical feasibility to utilize raw biogas for methanol production at acidic conditions.


Assuntos
Amônia , Metano , Reatores Biológicos , Estudos de Viabilidade , Metanol , Oxirredução
18.
Artigo em Inglês | MEDLINE | ID: mdl-33808312

RESUMO

The International Health Regulations (2005) promote national capacity in core institutions so that countries can better detect, respond to and recover from public health emergencies. In accordance with the 'all hazards' approach to public health risk, this systematic review examines poisoning and toxic exposures in Myanmar. A systematic literature search was undertaken to find articles pertaining to poisoning in Myanmar published between 1998 and 2020. A number of poisoning risks are identified in this review, including snakebites, heavy metals, drugs of abuse, agrochemicals and traditional medicine. Patterns of poisoning presented in the literature diverge from poisoning priorities reported in other lower-middle income countries in the region. The experience of professionals working in a Yangon-based poison treatment unit also indicate that frequently observed poisoning as a result of pharmaceuticals, methanol, and petroleum products was absent from the literature. Other notable gaps in the available research include assessments of the public health burden of poisoning through self-harm, household exposures to chemicals, paediatric risk and women's occupational risk of poisoning. There is a limited amount of research available on poisoning outcomes and routes of exposure in Myanmar. Further investigation and research are warranted to provide a more complete assessment of poisoning risk and incidence.


Assuntos
Envenenamento , Saúde Pública , Criança , Feminino , Humanos , Renda , Metanol , Mianmar/epidemiologia , Envenenamento/epidemiologia
19.
Artigo em Inglês | MEDLINE | ID: mdl-33809113

RESUMO

Decreased greenhouse gas emissions (GHG) are urgently needed in view of global health threat represented by climate change. The goal of this paper is to test the validity of the Environmental Kuznets Curve (EKC) hypothesis, considering less common measures of environmental burden. For that, four different estimations are done, one considering total GHG emissions, and three more taking into account, individually, the three main GHG gases-carbon dioxide (CO2), nitrous oxide (N2O), and methane gas (CH4)-considering the oldest and most recent economies adhering to the EU27 (the EU 15 (Old Europe) and the EU 12 (New Europe)) separately. Using panel dynamic fixed effects (DFE), dynamic ordinary least squares (DOLS), and fully modified ordinary least squares (FMOLS) techniques, we validate the existence of a U-shaped relationship for all emission proxies considered, and groups of countries in the short-run. Some evidence of this effect also exists in the long-run. However, we were only able to validate the EKC hypothesis for the short-run in EU 12 under DOLS and the short and long-run using FMOLS. Confirmed is the fact that results are sensitive to models and measures adopted. Externalization of problems globally takes a longer period for national policies to correct, turning global measures harder and local environmental proxies more suitable to deeply explore the EKC hypothesis.


Assuntos
Gases de Efeito Estufa , Dióxido de Carbono/análise , Desenvolvimento Econômico , Europa (Continente) , Efeito Estufa , Gases de Efeito Estufa/análise , Metanol , Óxido Nitroso/análise
20.
J Chromatogr A ; 1645: 462091, 2021 May 24.
Artigo em Inglês | MEDLINE | ID: mdl-33845250

RESUMO

In this study, a background electrolyte capable to separate and quantify inorganic cations in high ionic strength samples by UV-absorption indirect detection was designed. In this regard, the four most abundant monovalent and divalent cations in earth crust (K+, Na+, Ca+2, Mg+2) were selected as model compounds. A group of small carboxylic acids and, several toluidines and pyridines were evaluated as mild strength complexing agents and chromophoric probes, respectively. The optimized background electrolyte was composed of 200 mM 2,4,6-trimethylpyridine as the chromophoric probe, 250 mM lactic acid as the weak complexing agent and pH buffering reagent (adjusted to pH 4.5), and 5% v/v methanol as organic solvent modifier. Based on a minimum number of components, it provided outstanding separation performance in less than 4 min in a wide linear dynamic range (10 - 2500 µg·mL-1). Performances were contrasted against a reference method based on conductometric detection. Furthermore, studies of separation efficiency and peak shape were carried out at different analyte concentrations in high electric conductivity solutions. The herein developed method demonstrated exceptional features in terms of limits of detection (~10 µg·mL-1), resolution, speed of analysis, sensitivity and peak capacity in high electric conductivity samples. Moreover, the method was successfully applied to high ionic strength samples such as rock digest, sea water, soy sauce and isotonic drinks.


Assuntos
Cátions/análise , Eletrólitos/química , Eletroforese Capilar/métodos , Espectrofotometria Ultravioleta/métodos , Ácido Láctico/química , Limite de Detecção , Metanol/química , Concentração Osmolar , Piridinas/química
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