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1.
Zhongguo Dang Dai Er Ke Za Zhi ; 22(3): 231-237, 2020 Mar.
Artigo em Chinês | MEDLINE | ID: mdl-32204759

RESUMO

OBJECTIVE: To identify risk factors for minimally invasive surfactant administration (MISA) failure in the treatment of preterm infants with respiratory distress syndrome (RDS) and the influence of MISA failure on neonatal outcome. METHODS: A retrospective analysis was performed for the clinical data of 148 preterm infants with a gestational age of ≤32 weeks and a clinical diagnosis of RDS, who were admitted to the neonatal intensive care unit of eight tertiary hospitals in Beijing, Tianjin and Hebei Province from July 1, 2017 to December 31, 2018 and were treated with MISA (bovine pulmonary surfactant, PS). According to whether MISA failure (defined as the need for mechanical ventilation within 72 hours after MISA) was observed, the infants were divided into two groups: MISA failure group (n=16) and MISA success (n=132). A logistic regression analysis was used to investigate the risk factors for MISA failure and its influence on neonatal outcome. RESULTS: The MISA failure rate was 10.8% (16/148). The logistic regression analysis showed that a high incidence rate of grade >II RDS before PS administration, low mean arterial pressure and high pulse pressure before administration, a low dose of initial PS administration, and long injection time and operation time were the risk factors for MISA failure (OR=5.983, 1.210, 1.183, 1.055, 1.036, and 1.058 respectively, P<0.05). After the control for the above risk factors, the logistic regression analysis showed that the MISA failure group had a significantly higher incidence rate of bronchopulmonary dysplasia (BPD) (OR=8.537, P<0.05). CONCLUSIONS: A high grade of RDS, a low mean arterial pressure, and a high pulse pressure before administration are independent risk factors for MISA failure, and a low dose of initial PS administration, a long injection time, and a long operation time may increase the risk of MISA failure. MISA failure may increase the incidence rate of BPD in preterm infants.


Assuntos
Surfactantes Pulmonares/uso terapêutico , Síndrome do Desconforto Respiratório do Recém-Nascido/tratamento farmacológico , Animais , Displasia Broncopulmonar , Bovinos , Humanos , Recém-Nascido , Recém-Nascido Prematuro , Respiração Artificial , Estudos Retrospectivos , Fatores de Risco , Tensoativos
2.
Bioresour Technol ; 304: 123021, 2020 May.
Artigo em Inglês | MEDLINE | ID: mdl-32086031

RESUMO

The present study aimed to enhance the biomethanation potential of mixed microalgae via cost effective surfactant coupled ultrasonic homogenization (SCUH). Mixed microalgae biomass was harvested using a coagulant (Alum) from a raceway pond. The harvested algal biomass was subjected to ultrasonic homogenization (UH) by varying the power from 100 to 180 W. A maximal soluble organic release of 2131 mg/L was achieved at an ultrasonic input energy (UIE) of 25200 kJ/kg TS. In order to enhance soluble organic release and to reduce energy spent, the optimized condition of ultrasonic pretreatment was coupled with varying sodium dodecyl sulphate (SDS) dosage. A higher solubilization of 30.5% was achieved at a UIE of 4200 kJ/kg SS with surfactant dosage of 0.02 g SDS/g SS for SCUH. SCUH showed higher methane production of 358 mL/g COD when compared to UH (185.9 mL/g COD), SCUH was economically feasible than UH.


Assuntos
Microalgas , Anaerobiose , Biomassa , Metano , Tanques , Tensoativos , Ultrassom
3.
Environ Sci Process Impacts ; 22(2): 430-441, 2020 Feb 26.
Artigo em Inglês | MEDLINE | ID: mdl-32003378

RESUMO

Quaternary ammonium compounds (QACs) are widely applied as surfactants and biocides in cleaning and personal-care products. Because of incomplete removal during wastewater treatment, QACs are present in wastewater effluents, with which they are discharged into natural waters, where they accumulate in sediments. To assess the levels of QACs in aquatic environments, a liquid chromatography high-resolution mass spectrometry method using both target and suspect screening was developed. The water and sediment sample preparation, measurement, and data analysis workflow were optimized for 22 target compounds with a wide range of hydrophobicity, including ionic liquids that have potential use as solvents and QACs common in personal-care and sanitizing products. In wastewater effluents, average concentrations of all target and suspect QACs combined ranged from 0.4 µg L-1 to 6.6 µg L-1. Various homologs of benzylalkyldimethylammonium (BAC) and dialkyldimethylammonium (DADMAC) as well as the ionic liquid butylpyridinium and 15 suspect QACs were detected in at least one wastewater effluent sample. A spatial profile of sediment samples in a lake demonstrated potential inputs from both municipal wastewater effluent and agricultural sources for BACs. In sediment cores, two distinct trends of temporal QAC accumulation were observed. In lakes with large watersheds and mixed domestic and industrial wastewater sources (Lake Pepin and Duluth Harbor), peak concentrations of QACs were found at depths corresponding to deposition in the 1980s and decreases after this time are attributed to improved wastewater treatment and source control. In a smaller lake with predominantly domestic wastewater inputs (Lake Winona), concentrations of QACs increased slowly over time until today.


Assuntos
Líquidos Iônicos , Águas Residuárias , Poluentes Químicos da Água , Lagos , Compostos de Amônio Quaternário , Tensoativos
4.
J Agric Food Chem ; 68(9): 2684-2695, 2020 Mar 04.
Artigo em Inglês | MEDLINE | ID: mdl-32083874

RESUMO

Dioxyethene fragment (-(OCH2CH2)2-) was introduced into traditional alkyl ß-d-glucopyranosides to ameliorate the water solubility, and eight nonionic surfactants, that is, alkoxy ethoxyethyl ß-d-glucopyranosides with alkyl chain lengths (n = 6-16), were synthesized and characterized. Their hydrophilic and lipophilic balance number, water solubility, critical micelle concentration (cmc), γcmc, Γmax, and hygroscopic rate decreased with an increase in the alkyl chain length. Hexadecoxy ethoxyethyl ß-d-glucopyranoside had no water solubility at 25 °C. Decoxy ethoxyethyl ß-d-glucopyranoside had the best emulsifying property in the toluene/water and n-octane/water systems and the strongest foaming property, whereas dodecoxy ethoxyethyl ß-d-glucopyranoside had the best emulsifying property in the rapeseed oil/water system. Such ß-d-glucopyranosides (n = 6-12) exhibited excellent surface activity. In addition, for the binary mixture of alkoxy ethoxyethyl ß-d-glucopyranosides (n = 8, 10, 12) and sodium dodecyl sulfate or cetyl trimethyl ammonium chloride, their cmc values were lower than the pure ß-d-glucopyranosides, indicating that they had synergistic interactions. The fan focal conic textures of alkoxy ethoxyethyl ß-d-glucopyranosides (n = 7-16) were observed during the cooling process under a polarizing optical microscope. Alkoxy ethoxyethyl ß-d-glucopyranosides (n = 14, 16) had the related melting points and the clear points with differential scanning calorimetry. With ß-d-glucopyranosides (n = 6-16) and n-butanol as the surfactant and cosurfactant, respectively, and with cyclohexane as the oil phase, the related microemulsion areas in their pseudoternary phase diagram system were investigated with the visual observation at 25 °C. Along with the slashing requirements of petroleum consumption, environmental protection, and green and sustainable development, nonionic sugar-based alkoxy ethoxyethyl ß-d-glucopyranosides should be expected to have their potential practical application because of their strengthened hydrophilicity, improved water solubility, and enhanced surface activity.


Assuntos
Glucosídeos/química , Tensoativos/química , Varredura Diferencial de Calorimetria , Interações Hidrofóbicas e Hidrofílicas , Solubilidade
5.
Chemosphere ; 244: 125534, 2020 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-32050335

RESUMO

Perfluoroalkyl acids (PFAAs) bioaccumulate in crops, with uptake being particularly high for short-chain PFAAs that are constantly transported with transpiration water to aerial plant parts. Due to their amphiphilic surfactant nature and ionized state at environmental pH, predicting the partitioning behavior of PFAAs is difficult and subject to considerable uncertainty, making experimental data highly desirable. Here, we applied a plant uptake model that combines advective flux with measured partition coefficients to reproduce the set of empirically derived plant uptake and soil-partitioning data for nine PFAAs in red chicory, in order to improve the mechanistic understanding and provide new insights into the complex uptake processes. We introduced a new parameter for retarded uptake (R) to explain the slow transfer of PFAA across biomembranes of the root epidermis, which has led to low transpiration stream concentration factors (TSCFs) presented in literature so far. We estimated R values for PFAAs using experimental data derived for red chicory and used the modified plant uptake model to simulate uptake of PFAA into other crops. Results show that this semi-empirical model predicted PFAAs transport to shoots and fruits with good accuracy based on experimental root to soil concentration factors (RCFdw) and soil to water partition coefficients (Kd) as well as estimated R values and plant-specific data for growth and transpiration. It can be concluded that the combination of rather low Kd with high RCFdw and the absence of any relevant loss are the reason for the observed excellent plant uptake of PFAAs.


Assuntos
Ácidos Alcanossulfônicos/metabolismo , Fluorcarbonetos/metabolismo , Modelos Químicos , Plantas/metabolismo , Poluentes do Solo/metabolismo , Ácidos Alcanossulfônicos/análise , Produtos Agrícolas/crescimento & desenvolvimento , Monitoramento Ambiental , Fluorcarbonetos/análise , Frutas/química , Solo , Poluentes do Solo/análise , Poluentes do Solo/química , Tensoativos/análise
6.
Sci Total Environ ; 711: 135099, 2020 Apr 01.
Artigo em Inglês | MEDLINE | ID: mdl-32000342

RESUMO

The rising demand for surfactants by the pharmaceuticals and cosmetic industries has generated vast amounts of petroleum-based synthetic surfactants, which are often toxic and non-degradable. Owing to their low toxicity, stability in extreme conditions, and biodegradability, biosurfactants could represent a sustainable alternative. The present study aimed to maximize the production of rhamnolipids (RL) from Pseudomonas aeruginosa by optimizing glucose concentration, temperature, and C/N and C/P ratios. After 96 h of cultivation at 37 °C, the final RL concentration was 4.18 ± 0.19 g/L with a final yield of 0.214 ± 0.010 g/gglucose when pure glucose was used as a carbon source. At present, the main obstacle towards commercialization of RL production is economic sustainability, due to the high cost of downstream processes and media components. For this reason, a renewable source such as wood hydrolysates (from birch and spruce woodchips) was examined here as a possible source of glucose for RL production. Both hydrolysates proved to be adequate, resulting in 2.34 ± 0.17 and 2.31 ± 0.10 g/L of RL, respectively, and corresponding yields of 0.081 ± 0.006 and 0.089 ± 0.004 g/gsugar after 96 h. These results demonstrate the potential of using renewable biomass for the production of biosurfactants and, to the best of our knowledge, they constitute the first report on the use of wood hydrolysates for RL production.


Assuntos
Pseudomonas aeruginosa , Biomassa , Florestas , Glicolipídeos , Petróleo , Tensoativos
8.
Mar Pollut Bull ; 151: 110804, 2020 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-32056599

RESUMO

Here, we report results from a 15-day mesocosm experiment examining changes in estimated oil equivalents (EOEs), n-alkanes (n-C10 to n-C35), polycyclic aromatic hydrocarbons (PAHs) and petroleum biomarkers. Water accommodated fractions (WAF) of oil and diluted chemically enhanced WAF (DCEWAF) were prepared and concentrations of oil residues determined on day 0, 3 and 15, respectively. Significant removals of n-alkane and PAHs were observed starting from day 3. The n-C17/pristane and n-C18/phytane ratios suggested that the n-alkane removal was due to biodegradation in the mesocosms. The ratios of C2-dibenzothiophenes/C2-phenanthrenes (D2/P2) and C3-dibenzothiophenes/C3-phenanthrenes (D3/P3) were found to be stable through the experiment. DCEWAF treatment had longer half-lives for most n-alkanes but shorter half-lives for most PAHs than the WAF treatment. Most petroleum biomarkers were stable throughout the experiment. However, depletion of TAS (tricyclic aromatic steroids) was observed on day 15 of DCEWAF treatment.


Assuntos
Ecossistema , Poluição por Petróleo , Petróleo , Tensoativos , Poluentes Químicos da Água , Hidrocarbonetos , Hidrocarbonetos Policíclicos Aromáticos
9.
Chem Biol Interact ; 317: 108962, 2020 Feb 01.
Artigo em Inglês | MEDLINE | ID: mdl-31982400

RESUMO

Quaternary ammonium compounds (e.g., benzalkonium chloride (BAC) and cetylpyridinium chloride (CPC)) constitute a group of cationic surfactants are widely used for personal hygiene and medical care despite the potential pulmonary toxicity. To examine whether BAC and CPC aerosols deposited in the alveolar region alter pulmonary function, we studied the effects on pulmonary surfactant using two-step in vitro models; cytotoxicity using A549 alveolar epithelial cell and changes in surface activity of the pulmonary surfactant monolayer using both Surfacten® and 1,2-dipalmitoyl-sn-glycero-3-phosphocholine (DPPC). Cell viability was decreased with BAC and CPC dose-dependently. A comparison of cytotoxicity among BAC homologues with different length of alkyl chain showed that C16-BAC, which has the longest alkyl chain, was more cytotoxic than C12- or C14-BAC. Caspase-3/7 activity and cleaved form of caspase-3 and PARP were increased in BAC- and CPC-exposed cells. The elevated caspase-3/7 activity and their cleaved active forms were abolished by caspase-3-inhibitor. Furthermore, we examined the features of the surface pressure/trough area (π-A) isotherm by the Langmuir-Wilhelmy method and atomic force microscopy (AFM) images of lipid monolayers on a subphase containing BAC, CPC, or pyridinium chloride (PC, as a control). The π-A isotherms showed that addition of BAC or CPC yielded dose-dependent increases in surface pressure without compression, indicating that BAC and CPC expand the isotherm to larger areas at lower pressure. The collapse pressure diminished with increasing concentration of CPC. Topographic images indicated that BAC and CPC resulted in smaller condensed lipid domains compared to the control. Conversely, PC without hydrocarbon tail group, showed no cytotoxicity and did not change the isotherms and AFM images. These results indicate that BAC and CPC cause cell death via caspase-3-dependent apoptotic pathway in A549 cells and alter the alveolar surfactant activity. These effects can be attributed to the long alkyl chain of BAC and CPC.


Assuntos
Apoptose/efeitos dos fármacos , Compostos de Benzalcônio/farmacologia , Cetilpiridínio/farmacologia , Células Epiteliais/efeitos dos fármacos , Pulmão/citologia , Mucosa Respiratória/citologia , Células A549 , Compostos de Benzalcônio/química , Sobrevivência Celular/efeitos dos fármacos , Cetilpiridínio/química , Humanos , Tensoativos/metabolismo
10.
Phys Chem Chem Phys ; 22(6): 3490-3498, 2020 Feb 14.
Artigo em Inglês | MEDLINE | ID: mdl-31990285

RESUMO

The liquid structures of six choline carboxylate/amino acid ionic liquids (bio-ILs) and their mixtures with water and various n-alkanols have been investigated by small-angle X-ray scattering (SAXS). The ILs exhibit long-range amphiphilic nanostructure comprised of polar and apolar domains that can be controlled by choice of anion, and which is tolerant to water dilution. Mixtures with n-alkanols can lead to marked changes in domain size and ordering. Utilising the Teubner-Strey model, we find amphiphilicity factors in many of these mixtures are comparable to those observed in conventional microemulsions, and that cooperative assembly in bio-IL/alkanol mixtures can enhance amphiphilicity, with potential to improve performance in a range of applications.


Assuntos
Aminoácidos/química , Ácidos Carboxílicos/química , Colina/química , Líquidos Iônicos/química , Nanoestruturas/química , Tensoativos/química
11.
Chem Commun (Camb) ; 56(13): 1988-1991, 2020 Feb 13.
Artigo em Inglês | MEDLINE | ID: mdl-31960852

RESUMO

Kinugasa reactions hold potential for bioorthogonal chemistry in that the reagents can be biocompatible. Unlike other bioorthogonal reaction products, ß-lactams are potentially reactive, which can be useful for synthesizing new biomaterials. A limiting factor for applications consists of slow reaction rates. Herein, we report an optimized aqueous copper(i)-catalyzed alkyne-nitrone cycloaddition involving rearrangement (CuANCR) with rate accelerations made possible by the use of surfactant micelles. We have investigated the factors that accelerate the aqueous CuANCR reaction and demonstrate enhanced modification of a model membrane-associated peptide. We discovered that lipids/surfactants and alkyne structure have a significant impact on the reaction rate, with biological lipids and electron-poor alkynes showing greater reactivity. These new findings have implications for the use of CuANCR for modifying integral membrane proteins as well as live cell labelling and other bioorthogonal applications.


Assuntos
Reação de Cicloadição/métodos , Lipídeos/química , Tensoativos/química , Água/química , Alquinos/química , Azidas/química , Catálise , Cobre/química , Proteínas de Membrana/química
12.
J Photochem Photobiol B ; 203: 111762, 2020 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-31896049

RESUMO

Activation of photocatalytic titania by ultraviolet-A (UVA) radiation has been proposed as a good approach for combating bacteria. Titania powder, in solution or immobilized on a surface, has excellent UVA-assisted killing properties on several microorganisms. However, these properties could not be demonstrated in biofilms of Pseudomonas aeruginosa, a resistant opportunistic human pathogen that can cause severe complications in patients who are immunocompromised or have burn wounds or cystic fibrosis. P. aeruginosa biofilms have detrimental effects on health and industry, causing serious economic damage. In this study, the effect of titania photocatalysis for controlling P. aeruginosa biofilms was investigated by employing different coatings obtained through sol-gel and evaporation-induced self-assembly. Biofilms were grown on non-mesoporous and mesoporous titania surfaces with different pore sizes, which were achieved based on the use of surfactants Brij-58 and Pluronics-F127. In addition, two structural forms of titania were assayed: amorphous and anatase. As well as inhibiting biofilm formation, these coatings significantly enhanced the bactericidal effect of UVA on P. aeruginosa biofilms. The most efficient surface with regard to total antibacterial effect was the mesoporous Brij-58-templated anatase film, which, compared to control biofilms, decreased the number of viable bacteria by about 5 orders, demonstrating the efficacy of this methodology as a disinfection system.


Assuntos
Biofilmes/efeitos dos fármacos , Nanopartículas Metálicas/toxicidade , Pseudomonas aeruginosa/fisiologia , Titânio/química , Raios Ultravioleta , Biofilmes/efeitos da radiação , Catálise , Nanopartículas Metálicas/química , Porosidade , Tensoativos/química
13.
Bioresour Technol ; 302: 122815, 2020 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-32000131

RESUMO

Three widely-used surfactants, rhamnolipid (RL), sophorolipid (SL) and sodium dodecyl benzene sulfonate (SDBS), were chosen to investigate their effects on the nitrification systems treating step-wised triclosan (TCS). Surfactants had little effects on nitrification. Surfactants could promote the desorption of TCS and enhance the TCS biodegradation in nitrification systems. And TCS biodegradation efficiencies obtained with RL, SL and SDBS were 1.25, 1.23 and 1.14 times higher than the control with 9.0 mg/L TCS, respectively. Illumina MiSeq sequencing showed that Amaricoccus could be resistant to TCS. And Amaricoccus, detected with RL, SL and SDBS, were more abundant than the control. DNA-based stable isotope probing assays revealed Amaricoccus was the major TCS degrader. And the addition of surfactants could obviously increase the diversity of active TCS degraders, especially for biosurfactants. It seems that the addition of surfactants showed positive effects for the nitrification systems treating TCS wastewater.


Assuntos
Triclosan , DNA , Isótopos , Nitrificação , Tensoativos
14.
Environ Sci Technol ; 54(3): 1513-1521, 2020 02 04.
Artigo em Inglês | MEDLINE | ID: mdl-31922402

RESUMO

Zwitterionic, cationic, and anionic per- and polyfluoroalkyl substances (PFASs) are identified in aqueous film-forming foam (AFFF) concentrates and AFFF-impacted sites. However, the mobility potential of zwitterionic and cationic PFASs is poorly understood, preventing reliable site assessment. The study aimed to elucidate the mobility behaviors of PFASs of various charge states in saturated soil-water systems and assess critical influencing factors. Five anionic, three zwitterionic, and one cationic PFASs were investigated in five soils through batch sorption experiments. Pairwise comparison revealed that the quaternary ammonium group imparted a strong affinity of cationic perfluorooctaneamide ammonium compound (PFOAAmS) for soils. The influence of the quaternary ammonium group is mitigated in polyfluoroalkyl betaines, yet perfluorooctane sulfonamidoalkyl betaine (PFOSB) showed strong sorption in selected soils. Two soil bulk properties showed some correlations with the soil-water distribution coefficient (Kd). A positive correlation with the fraction of soil organic carbon was found only for anionic PFASs, whereas cation exchange capacity had an approximate positive correlation with Kd only for PFOAAmS. Water chemistry (Ca2+ and pH) influences the sorption of nonanionic PFASs in very distinct fashions or even in opposite trends to what was known for anionic PFASs. Sorption was insensitive to pH changes except for PFOSB; PFOSB underwent profound sorption reduction because its speciation occurs around neutral pH, while the two other betaines and PFOAAmS have pKa values that are outside of the environmentally relevant range. The lack of correlations suggests that the transport potential of PFASs is probably highly site-specific. It remains a challenge in deciphering PFAS sorption mechanisms and predicting how AFFF plumes migrate.


Assuntos
Fluorcarbonetos , Poluentes do Solo , Poluentes Químicos da Água , Carbono , Estrutura Molecular , Solo , Tensoativos
15.
Chemosphere ; 242: 125237, 2020 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-31896179

RESUMO

The presence of surfactants in biofilters could enhance hydrophobic VOC removal. In this study, blood agar plate, methylene blue agar plate and a culture with n-hexane as the only carbon source were used to screen strains that could biodegrade n-hexane and produce biosurfactants simultaneously. The effects of n-hexane concentration on n-hexane removal and biosurfactant production were also investigated. Results showed that such a strain identified to be Pseudomonas sp. Strain NEE2 was successfully isolated from oil-polluted soils. The biosurfactants production by this strain were dependent on the initial concentration of n-hexane (132-2640 mg/L). At the concentration of 2640 mg/L of n-hexane, the biosurfactants promoted n-hexane removal. At 132 mg/L of n-hexane, n-hexane removal efficiency on day 2 exceeded 60%. The synergistic mechanisms of n-hexane removal and biosurfactant production by Pseudomonas sp. Strain NEE2 were discussed including the enhanced mass transfer from gas to liquid phase, within the biofilm phase and biodegradation at the presence of biosurfactants as well as the consequently enhanced production of the biosurfactants. These results in this study proved that it is possible for microorganisms utilizing the synergistic effect of hydrophobic VOC degradation and biosurfactant production for cost-effective hydrophobic VOC removal in biofilters.


Assuntos
Hexanos/metabolismo , Poluição por Petróleo , Pseudomonas/metabolismo , Poluentes do Solo/metabolismo , Biodegradação Ambiental , Interações Hidrofóbicas e Hidrofílicas , Solo , Tensoativos/química
16.
Environ Sci Process Impacts ; 22(2): 271-284, 2020 Feb 26.
Artigo em Inglês | MEDLINE | ID: mdl-31912080

RESUMO

The physical processes and time scales underlying the evolution of surface tension in atmospheric solution droplets are largely unaccounted for in present models describing cloud droplet formation. Adsorption of surface-active molecules at the surface of a solution droplet depresses the droplet surface tension but also depletes solute from the droplet bulk, which have opposing and sometimes canceling effects in cloud droplet formation. In this work, we study the effect of time-evolving surface tension for cloud droplet activation of particles composed of Nordic Aquatic Fulvic Acid (NAFA) mixed with sodium chloride (NaCl). We model the formation of cloud droplets using Köhler theory with surface tension depression and bulk/surface partitioning evaluated from two different thermodynamic surface models. Continuous ternary parameterizations were constructed from surface tension measurements of macroscopic droplets at different time steps after the formation of a droplet surface. The predicted results are compared to previous measurements of mixed NAFA-NaCl cloud condensation nuclei (CCN) activity and a bulk solution model that does not take the NAFA bulk/surface partitioning equilibrium into account. Whereas the bulk model shows a trend in cloud droplet formation following that of macroscopic surface tension depression with time, the variation with time essentially disappears when bulk/surface partitioning is taken explicitly into account during droplet activation. For all equilibrium time steps considered, the effect of surface tension depression in the NAFA-NaCl system is counteracted by the depletion of solute from the finite-sized droplet bulk phase. Our study highlights that a comprehensive data set is necessary to obtain continuous parameterizations of surface tension and other solution properties required to fully account for the bulk/surface partitioning in growing droplets. To our knowledge, no similar data set currently exists for other aqueous organic systems of atmospheric interest. Additional work is necessary to deconvolve the effects of bulk/surface partitioning in the context of time-evolution on cloud droplet activation and to determine whether the results presented here can be further generalized.


Assuntos
Tensoativos , Aerossóis , Soluções , Tensão Superficial
17.
J Basic Microbiol ; 60(1): 14-21, 2020 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-31696960

RESUMO

Gordoniae are one of the most promising hydrocarbon-oxidizing actinobacteria. Here we present the genome sequence analysis of thermotolerant strain Gordonia sp. 1D isolated from oil-refinery soil. It is capable of alkane consumption and biosurfactant production at temperatures of up to 50°C. Gordonia sp. 1D demonstrates maximum biosurfactant production when grown on hexadecane, and at 40°C it was slightly higher than at 27°C: 35 and 39 mN/m, respectively. For the first time, it was experimentally confirmed that the carbohydrate component of extracellular biosurfactants produced by strain 1D is trehalose. In addition, genes for the production of trehalose lipid biosurfactants were identified. The genetic determinants for two different pathways for trehalose synthesis were found. The strain carries genes otsA and otsB involved in de novo trehalose biosynthesis. Moreover, the genes treY and treZ responsible for trehalose biosynthesis from maltooligosaccharides and starch or glycogen were identified.


Assuntos
Genoma Bacteriano/genética , Gordonia (Bactéria)/genética , Gordonia (Bactéria)/metabolismo , Trealose/metabolismo , Genes Bacterianos , Glicolipídeos/química , Glicolipídeos/metabolismo , Gordonia (Bactéria)/classificação , Hidrocarbonetos/metabolismo , Petróleo/microbiologia , Filogenia , Microbiologia do Solo , Tensoativos/química , Tensoativos/metabolismo , Temperatura Ambiente
18.
Chem Biol Interact ; 315: 108870, 2020 Jan 05.
Artigo em Inglês | MEDLINE | ID: mdl-31669216

RESUMO

The toxic effects of poly(HEMA)-based polymeric nanoparticles must be analyzed before their biomedical applications as drug delivery systems. The aim of the study was to characterize and evaluate the toxicity for its biocompatibility of a newly synthesized l-glutamic acid-g-p(HEMA) polymeric nanoparticle The nanoparticle was synthesized with surfactant-free emulsion polymerization and grafting techniques. Grafting efficiency was estimated at 58%. The nanoparticle shape was verified as nearly spherical by scanning electron microscopy. Atomic force microscopy images showed a rough surface topography. The nanoparticle had an average size of ~194.6 nm on zeta analysis, and the zeta potential value was -18 mV. Fourier transformed infrared spectroscopy revealed spectra from 750 to 4000 cm-1 and characteristic peaks of stretching bands. The swelling ratio was 46%. With 24-h exposure, p(HEMA) and l-glutamic acid-g-p(HEMA) did not have cytotoxic effects on a human bronchial epithelial cell line (16HBE) and human monocyte cell line by water-soluble tetrazolium salt 1 (WST-1) assay and lactate dehydrogenase assay (LDH). It did not show genotoxic potential by comet assay and did not have mutagenic effects on Salmonella typhimurium TA98, TA100, TA1535 and TA1537 strains by Ames test. The nanoparticle at 160 µg/ml showed 2% hemolytic activity on erythrocytes. On cell migration assay, the percentage closure difference between exposed and control cells was estimated at 21%. We found no irritation effect on Hen's egg test-chorioallantoic membrane test. We determined that the polymeric nanoparticle l-glutamic acid-g-p(HEMA) was biocompatible and has potential for use in a drug delivery system.


Assuntos
Metacrilatos/química , Metacrilatos/toxicidade , Nanopartículas/química , Nanopartículas/toxicidade , Polímeros/química , Polímeros/toxicidade , Animais , Materiais Biocompatíveis/química , Materiais Biocompatíveis/toxicidade , Linhagem Celular , Galinhas , Sistemas de Liberação de Medicamentos/métodos , Emulsões/química , Emulsões/farmacologia , Emulsões/toxicidade , Eritrócitos/efeitos dos fármacos , Humanos , Monócitos/efeitos dos fármacos , Tamanho da Partícula , Coelhos , Salmonella typhimurium/efeitos dos fármacos , Propriedades de Superfície/efeitos dos fármacos , Tensoativos/química
19.
Chemosphere ; 242: 125109, 2020 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-31675586

RESUMO

Organoclays have been applied as efficient adsorbents for pharmaceutical pollutants from aqueous solution. In this work, dodecylpyridinium chloride (C12pyCl) and hexadecylpyridinium chloride (C16pyCl) cationic surfactants were used for the preparation of organobentonites destined for diclofenac sodium (DFNa) adsorption, an anionic drug widely detected in wastewater. The organofunctionalization of the clay samples was performed under microwave irradiation at 50 °C for 5 min with surfactant amounts of 100% and 200% in relation to the cation exchange capacity (CEC) of the pristine bentonite. The amount of incorporated ammonium salts based on CHN elemental analysis was higher for all samples prepared with 200% of the CEC. The basal spacings of the organoclays ranged from 1.54 to 2.13 nm, indicating the entrance of organic cations into the interlayer spacing of the clay samples, and the spacing depended on the size of the alkyl organic chain. The hydrophobic character of the organobentonites was verified by thermogravimetry and infrared spectroscopy (FTIR). The adsorption isotherms showed that the drug capacity adsorption was influenced by the amount of surfactant incorporated into the bentonite, the packing density and the arrangement of the surfactants in the interlayer spacing. Zeta potential measurements of the organobentonites and FTIR analysis after drug adsorption suggested that electrostatic and nonelectrostatic interactions contributed to the mechanism of adsorption.


Assuntos
Bentonita/química , Diclofenaco/química , Adsorção , Anti-Inflamatórios não Esteroides/química , Cátions/química , Interações Hidrofóbicas e Hidrofílicas , Eletricidade Estática , Tensoativos/química , Água/química , Difração de Raios X
20.
Environ Pollut ; 256: 113416, 2020 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-31677871

RESUMO

Marine oil spill often causes contamination of drinking water sources in coastal areas. As the use of oil dispersants has become one of the main practices in remediation of oil spill, the effect of oil dispersants on the treatment effectiveness remains unexplored. Specifically, little is known on the removal of dispersed oil from contaminated water using conventional adsorbents. This study investigated sorption behavior of three prototype activated charcoals (ACs) of different particle sizes (4-12, 12-20 and 100 mesh) for removal of dispersed oil hydrocarbons, and effects of two model oil dispersants (Corexit EC9500A and Corexit EC9527A). The oil content was measured as n-alkanes, polycyclic aromatic hydrocarbons (PAHs), and total petroleum hydrocarbons (TPHs). Characterization results showed that the smallest AC (PAC100) offered the highest BET surface area of 889 m2/g and pore volume of 0.95 cm3/g (pHPZC = 6.1). Sorption kinetic data revealed that all three ACs can efficiently adsorb Corexit EC9500A and oil dispersed by the two dispersants (DWAO-I and DWAO-II), and the adsorption capacity followed the trend: PAC100 > GAC12 × 20 > GAC4 × 12. Sorption isotherms confirmed PAC100 showed the highest adsorption capacity for dispersed oil in DWAO-I with a Freundlich KF value of 10.90 mg/g∙(L/mg)1/n (n = 1.38). Furthermore, the presence of Corexit EC9500A showed two contrasting effects on the oil sorption, i.e., adsolubilization and solubilization depending on the dispersant concentration. Increasing solution pH from 6.0 to 9.0 and salinity from 2 to 8 wt% showed only modest effect on the sorption. The results are useful for effective treatment of dispersed oil in contaminated water and for understanding roles of oil dispersants.


Assuntos
Hidrocarbonetos/química , Poluição por Petróleo , Poluentes Químicos da Água/química , Adsorção , Alcanos , Carvão Vegetal/química , Cinética , Petróleo/análise , Hidrocarbonetos Policíclicos Aromáticos/análise , Hidrocarbonetos Policíclicos Aromáticos/química , Salinidade , Água do Mar/química , Tensoativos/química , Poluentes Químicos da Água/análise
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