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1.
Chemosphere ; 244: 125544, 2020 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-32050341

RESUMO

Bacterial mercury oxidation coupled to denitrification offers great potential for simultaneous removal of elemental mercury (Hg0) and nitric oxide (NO) in a denitrifying membrane biofilm reactor (MBfR). Four potentially contributory mechanisms tested separately, namely, membrane gas separation, medium absorption, biosorption and biotransformation, which contributed 4.9%/7.2%, 8.1%/8.9%, 38.8%/9.5% and 48.2%/84.9% of overall Hg0/NO removal in MBfR. Herein, Hg0 bio-oxidation, oxidative Hg0 biosorption and denitrification played leading roles in simultaneous removal of Hg0 and NO. Living microbes performed simultaneous Hg0 bio-oxidation and denitrification, in which Hg0 as electron donor was biologically oxidized to oxidized mercury (Hg2+), while NO as the terminal electron acceptor was denitrified to N2. The Hg2+ further complexed with humic acids in extracellular polymeric substances via functional groups (-SH, -OH, -NH- and -COO-) and formed humic acids bound mercury (HA-Hg). Non-living microbial matrix performed oxidative Hg0 biosorption, in which Hg0 may be physically adsorbed by cellular matrix, then non-metabolically oxidized to Hg2+ via oxidative complexation with -SH in humic acids and finally cleavage of S-H bond and surface charge transfer led to formation of HA-Hg. Therefore, bioconversion of Hg0 to HA-Hg by Hg0 bio-oxidation and oxidative Hg0 biosorption coupled with NO denitrification to N2 dynamically cooperated to accomplish simultaneous removal of Hg0 and NO in MBfR.


Assuntos
Reatores Biológicos/microbiologia , Mercúrio/metabolismo , Óxido Nítrico/metabolismo , Eliminação de Resíduos Líquidos/métodos , Poluentes Químicos da Água/metabolismo , Bactérias , Biofilmes , Desnitrificação , Substâncias Húmicas , Membranas , Mercúrio/análise , Oxirredução
2.
Nat Commun ; 11(1): 541, 2020 Jan 28.
Artigo em Inglês | MEDLINE | ID: mdl-31992713

RESUMO

The fast development of high-resolution electron microscopy (EM) demands a background-noise-free substrate to support the specimens, where atomically thin graphene membranes can serve as an ideal candidate. Yet the preparation of robust and ultraclean graphene EM grids remains challenging. Here we present a polymer- and transfer-free direct-etching method for batch fabrication of robust ultraclean graphene grids through membrane tension modulation. Loading samples on such graphene grids enables the detection of single metal atoms and atomic-resolution imaging of the iron core of ferritin molecules at both room- and cryo-temperature. The same kind of hydrophilic graphene grid allows the formation of ultrathin vitrified ice layer embedded most protein particles at the graphene-water interface, which facilitates cryo-EM 3D reconstruction of archaea 20S proteasomes at a record high resolution of ~2.36 Å. Our results demonstrate the significant improvements in image quality using the graphene grids and expand the scope of EM imaging.


Assuntos
Grafite/química , Microscopia Eletrônica/instrumentação , Microscopia Eletrônica/métodos , Fenômenos Químicos , Microscopia Crioeletrônica/métodos , Elétrons , Desenho de Equipamento , Processamento de Imagem Assistida por Computador , Membranas , Polímeros , Proteínas
3.
Water Res ; 172: 115509, 2020 Apr 01.
Artigo em Inglês | MEDLINE | ID: mdl-31986399

RESUMO

A MBR treating compost leachate was studied in order to link the operating parameters (solid and hydraulic retention time) to contaminant's specific bacterial catabolic activity. In this context, a lab-scale aerobic membrane bioreactor was operated for 200 days, at solid retention times (SRT) of 30 and 45 days and four different contaminant load rates. Results showed that increasing the food to microorganism ratio (F/M) by increasing the contaminant load rates lessened the selectivity pressure, which allowed the proliferation of subdominant operational taxonomic units (OTU) (relative abundance >3%) that were otherwise inhibited by highly adapted dominant OTUs (relative abundance >10%). Subsequently, increasing the SRT resulted in a lower species richness and the selection of two dominant types of bacteria: 1) genera with low growth rates that feed on non-limiting substrates or substrates with few competitors, and 2) genera with metabolisms that are highly specific to the available substrates and that can outcompete the other genera by using the substrate more efficiently. The bacterial population evolution observed during this study suggests that the mixed liquor population diversity and structure can be modulated with the operating conditions for the bioenhancement of contaminant specific catabolic activity. Identified dominant and subdominant genera were linked to the MBR's NH4+ and COD removal performances. Interestingly, nitrification performances were unaffected by the organic load rate and the Nitrosomonas relative abundance.


Assuntos
Bactérias , Reatores Biológicos , Membranas , Nitrificação , Nitrosomonas
4.
Bioresour Technol ; 296: 122314, 2020 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-31671329

RESUMO

Processing complexities associated with different lignocellulosic bioethanol production stages have hindered reaching full commercial capacity. Therefore, in this study efforts were made to remediate some issues associated with hydrolysis and fermentation, by the integration of immersed membrane bioreactors (iMBRs) into lignocellulosic bioethanol production process. In this regards, double-staged continuous saccharification-filtration and co-fermentation-filtration of wheat straw slurry was conducted using iMBRs at filtration fluxes up to 51.0 l.m-2.h-1 (LMH). The results showed a stable long-term (264 h) continuous hydrolysis-filtration and fermentation-filtration with effective separation of lignin-rich solids (up to 70% lignin) from hydrolyzed sugars, and separation of yeast cells from bioethanol stream at an exceptional filtration performance at 21.9 LMH. Moreover, the effect of factors such as filtration flux, medium quality and backwashing on fouling and cake-layer formation was studied. The results confirmed the process intensification potentials of iMBRs in tackling commonly faced technical obstacles in lignocellulosic bioethanol production.


Assuntos
Etanol , Lignina , Reatores Biológicos , Fermentação , Hidrólise , Membranas
5.
Bioresour Technol ; 296: 122301, 2020 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-31678707

RESUMO

The formation of the dynamic membrane (DM) in an anaerobic dynamic membrane bioreactor (AnDMBR) treating food waste was, previously, found to be beneficial to the stable performance of an anaerobic digestion system. This study examines the effect of shear velocity and feed concentration on the performance and microbial community of an AnDMBR treating food waste. The shear velocity was varied from 0.04 to 1.74 m/h, using three different feed concentrations (50, 80, and 100 g-COD/L). The highest average methane production rate of 2.6 L-CH4/L/d was achieved at a feed concentration and shear velocity of 100-g COD/L and 0.34 m/h, respectively. Increasing shear velocity, within certain limits, is beneficial to AnDMBR systems, promoting better mixing, substrate-biomass interactions, and DM layer formation. Methanosarcina flavescens proliferated (69%) at high shear velocities when acetic acid was the major volatile fatty acid. The abundance ratio between Bacteroidetes and Firmicutes showed a linear relationship to methanogenic performance.


Assuntos
Microbiota , Eliminação de Resíduos , Anaerobiose , Reatores Biológicos , Alimentos , Membranas , Metano
6.
Bioresour Technol ; 296: 122352, 2020 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-31708385

RESUMO

The aim of this work was to study reverse solute flux (RSF) from osmotic membrane bioreactor (OMBR) and consequent solute buildup in the feed side. A polyelectrolyte (PAA-Na) served as a draw solute (DS) to minimize RSF in OMBRs. In addition, a bioelectrochemical system (BES) was employed to drive accumulated cations from the feed/anode side into the cathode compartment, subsequently achieving PAA-Na DS recovery with the aid of high catholyte pH. Compared to the 1 M NH4HCO3 DS, the 0.48 g mL-1 PAA-Na DS produced consistently stable water flux, enhanced water recovery and increased ammonium removal efficiency. Due to a dynamic balance between PAA removal and continuing RSF, the residual PAA concentration was 72 mg L-1 on the feed side (27.0% of TOC). These results demonstrate the advantages of integrating a PAA-Na DS with a BES to mitigate RSF and to support further development of OMBR technology.


Assuntos
Polieletrólitos , Purificação da Água , Reatores Biológicos , Membranas , Membranas Artificiais , Osmose
7.
J Contemp Dent Pract ; 20(9): 1024-1028, 2019 Sep 01.
Artigo em Inglês | MEDLINE | ID: mdl-31797823

RESUMO

AIM: The aim of this study was to introduce the less invasive vestibule access tunneling in combination with platelet-rich fibrin (PRF) membrane for gingival recession treatment. MATERIALS AND METHODS: Seven subjects with Miller's class I or II buccal gingival recession were selected for this study. All subjects were treated with mucogingival surgery using the less invasive vestibule access tunneling in combination with PRF membrane. Clinical examination performed on each subject and the height of gingival recession was recorded preoperatively (baseline), and at 1 and 3 months postoperatively. The data were statistically analyzed using analysis of variance (ANOVA) with post hoc Tukey's LSD test to determine the significant difference between groups. Statistical significance level was set at 0.05. RESULTS: The results showed that there were significant differences in recession height between baseline and both 1 month and 3 months postoperatively (p < 0.05). Nevertheless, there was no significant difference between 1 and 3 months postoperatively (p > 0.05). All patients reported satisfactory esthetic results both at 1 and 3 months postoperatively. CONCLUSION: Mucogingival surgery using the less invasive vestibule access tunneling in combination with PRF membrane for gingival recession treatment provided optimal root coverage. CLINICAL SIGNIFICANCE: This article introduces a new tunnel technique in combination with PRF membrane for gingival recession treatment. Previous studies tried to make access using the tunnel technique performed through gingival sulcus. In this study, the access is performed through the vestibule region. Access from the vestibule can minimize the damage of gingival margin integrity, especially in patients with thin gingival biotype.


Assuntos
Retração Gengival , Fibrina Rica em Plaquetas , Estética Dentária , Humanos , Membranas , Retalhos Cirúrgicos , Resultado do Tratamento
8.
Water Sci Technol ; 80(6): 1011-1021, 2019 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-31799945

RESUMO

We investigated the operating conditions of a baffled membrane bioreactor (B-MBR) under which long-term stable operation can be achieved through the continuous operation of a pilot-scale B-MBR. Under appropriate operating conditions, the B-MBR was capable of achieving excellent treated water quality in terms of biochemical oxygen demand and concentration of total nitrogen. Excellent removal of total phosphorus was also achieved. In addition, the degree of membrane fouling was acceptable, indicating that stable continuous operation of a B-MBR is possible under the operating conditions adopted in the present study. Estimation of the specific energy consumption in hypothetical full-scale B-MBRs operated under the conditions recommended by the findings was also performed in this study. The results suggest that energy consumption in full-scale B-MBRs would be in the range of 0.20-0.22 kWh/m3. These results strongly suggest that energy consumption in MBR operation can be significantly reduced by applying the concept of a B-MBR.


Assuntos
Membranas Artificiais , Eliminação de Resíduos Líquidos , Reatores Biológicos , Membranas , Fósforo
9.
Urologe A ; 58(12): 1429-1434, 2019 Dec.
Artigo em Alemão | MEDLINE | ID: mdl-31705143

RESUMO

BACKGROUND: Since their clinical introduction in 2011, PSMA-PET/CT (PSMA: prostate-specific membrane antigen) as well as PSMA therapy of prostate cancer (PC) have spread rapidly worldwide. OBJECTIVES: To summarize the current knowledge about both PSMA-PET/CT and PSMA therapy of PC. METHODS: The knowledge derived from the literature as well as the authors' experiences were collected in this review. RESULTS: PSMA-PET/CT demonstrates a very high sensitivity and specificity for the detection of recurrent PC as well as for the primary staging of intermediate- and high-risk PC. PSMA therapy shows promising results in third-line treatment for patients with castration-resistant, metastatic PC. CONCLUSIONS: PSMA-PET/CT is meanwhile established as the gold standard for the detection of recurrent PC and is in the process of assuming the same role for primary staging of intermediate- to high-risk PC. PSMA therapy serves as a promising third-line therapy in an increasing number of centers.


Assuntos
Tomografia Computadorizada com Tomografia por Emissão de Pósitrons , Neoplasias da Próstata , Humanos , Masculino , Membranas , Recidiva Local de Neoplasia , Antígeno Prostático Específico , Neoplasias da Próstata/diagnóstico por imagem
10.
World J Microbiol Biotechnol ; 35(10): 162, 2019 Oct 14.
Artigo em Inglês | MEDLINE | ID: mdl-31612285

RESUMO

Various transient metal and metal oxide nanoparticles (NPs) have shown pronounced biological activity, including antibacterial action against different Gram-negative and Gram-positive bacteria including pathogens and drug-resistant ones. Thus, NPs can be applied in nanotechnology for controlling bacterial growth as well as in biomedicine for the treatment of various diseases. However, the mechanisms of these effects are not clear yet. This review is focused on the antibacterial effects of transient metal NPs, especially iron oxide (Fe3O4) and Ag NPs on Escherichia coli wild type and antibiotic-resistant strains. Ag NPs show more pronounced bactericidal effect than Fe3O4 NPs. Moreover, Ag NPs display more expressed antibacterial effect at low concentrations. Interestingly, kanamycin-resistant strain is more susceptible to Fe3O4 NPs than wild type strain. In order to explain the possible mechanisms of NP effects, in addition to the production of reactive oxygen species causing damage in cells, particularly, their membranes, the changes in the membrane-associated H+-translocating FOF1-ATPase activity, H+-fluxes through the bacterial membrane, redox potential and hydrogen yield by membrane-associated enzymes-hydrogenases, are discussed. We observed from the results that FOF1-ATPase could be a main target for NPs. A scheme of possible action mechanism is proposed.


Assuntos
Antibacterianos/farmacologia , Bactérias/efeitos dos fármacos , Membranas , Nanopartículas Metálicas/química , Farmacorresistência Bacteriana/efeitos dos fármacos , Escherichia coli/efeitos dos fármacos , Compostos Férricos , Nanotecnologia/métodos , Espécies Reativas de Oxigênio , Prata/farmacologia
11.
Biochimie ; 167: 145-151, 2019 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-31586653

RESUMO

The research literature on atherosclerosis includes findings investigating the atherosclerotic effect of oxysterols, which are the oxidation products of cholesterol; and the literature on oxysterols refers to mechanisms by which oxysterols cause phospholipid packing defects in cell membranes. This review synthesizes these two bodies of research findings to describe how oxysterols cause phospholipid packing defects within the membranes of vascular endothelial cells, potentially increasing cell permeability of low-density lipoprotein cholesterol which may lead to atheroma formation. Exogenous sources of oxysterols are provided by dietary intake of animal-based foods that contain cholesterol oxidation products. This review proposes an explanation for the anti-atherosclerotic effect of plant-based dietary patterns, which is attributed to restriction or avoidance of dietary oxysterol intake from animal-based foods. Furthermore, raw-milk cheeses play an important role in the traditional French diet-low oxysterol content in these unheated foods may contribute to the French paradox, in which reduced coronary heart disease is associated with a diet high in saturated fat and cholesterol.


Assuntos
Aterosclerose , LDL-Colesterol/metabolismo , Células Endoteliais/metabolismo , Membranas/metabolismo , Oxisteróis/metabolismo , Fosfolipídeos/metabolismo , Aterosclerose/dietoterapia , Aterosclerose/metabolismo , Aterosclerose/prevenção & controle , Dieta , Células Endoteliais/citologia , Humanos , Oxirredução , Compostos Fitoquímicos/farmacologia
12.
Environ Sci Technol ; 53(21): 12846-12855, 2019 Nov 05.
Artigo em Inglês | MEDLINE | ID: mdl-31593452

RESUMO

Given our vast methane reserves and the forecasted shortage of crude oil in the not too distant future, the conversion of methane into value-added liquid chemicals or fuels would be beneficial. The generated chemicals or fuels could augment the petroleum-dominated chemical market, and also satisfy the increasing demand for transportation fuels. While methane bioconversion to liquid chemicals has just been reported recently, there is limited understanding of the process. This study aims to clarify the potential electron acceptors that could support the process. Here we operated four membrane biofilm reactors (MBfRs) fed with nitrate, nitrite, oxygen at a relatively low rate, and oxygen at a relatively high rate, respectively, to study if they can support methane bioconversion to short-chain fatty acids (SCFAs) and the associated microbiological features. All tested electron acceptors facilitated methane bioconversion to SCFAs (ranging from 1.1 to 36.7 mg acetate L-1 d-1, or 3.4 to 114.6 mg acetate d-1 m-2 of biofilm). The carbon efficiency was estimated to be 7.9 ± 1.4% to 148.5 ± 1.3%, with an efficiency higher than 100%, suggesting the assimilation of other carbon, very likely CO2, into the products. A low oxygen supply rate of 46.4 ± 2.3 mg O2 d-1 m-2 was found to be the most favorable among all the electron conditions provided according to the SCFAs production rate and also the carbon utilization efficiency. Microbial characterization revealed that completely different communities evolved in the respective reactors, suggesting diverse microbial pathways exist for methane bioconversion into value-added chemicals.


Assuntos
Elétrons , Metano , Biofilmes , Reatores Biológicos , Ácidos Graxos Voláteis , Membranas
13.
Int J Oral Maxillofac Implants ; 34(5): 1132-1142, 2019.
Artigo em Inglês | MEDLINE | ID: mdl-31528864

RESUMO

PURPOSE: This study evaluated the efficacy of newly designed, laser-perforated pure titanium membranes for guided bone regeneration using beta-tricalcium phosphate (ß-TCP), and compared them with the existing membrane. MATERIALS AND METHODS: Bilateral acute lateral ridge defects were created in the mandibles of 12 dogs (four defects per animal), which were then randomly divided into two groups (six dogs each). The twenty-four bone defects in each group were then further divided into five groups. The groups were as follows: (1) F001M0, a prototype membrane without a frame plus ß-TCP (n = 5); (2) F001M1, a prototype membrane with a frame plus ß-TCP (n = 5); (3) FBS, an existing control membrane plus ß-TCP (n = 5); (4) control 1, ß-TCP without membrane and with covering flap only (n = 5); and (5) control 2, no treatment (no ß-TCP and no membrane) (n = 4). In all groups where ß-TCP was used, it was mixed with peripheral blood. The animals were necropsied at 6 or 12 weeks postoperatively (six dogs each), and samples were collected and processed for radiographic, histologic, and histomorphometric analyses. RESULTS: Among the three membrane groups, regenerated tissue and bone volume was greatest in the F001M1 group at both 6 and 12 weeks postoperatively, although differences among groups were not statistically significant. Bone mineral density was similar among the membrane groups. Histologic analysis revealed that immature fibroblasts were present on the laser-perforated portion at 6 weeks, which induced vascularization. In addition, more calcified bone was replaced beneath the prototypes than beneath the FBS membrane at 12 weeks. Histomorphometric analyses revealed that the calcific osseous areas at 12 weeks after surgery were significantly greater in the F001M1 and F001M0 groups than in the FBS group (P = .021, P = .032). Furthermore, the fibrous tissue areas beneath the membrane at 12 weeks postoperatively were significantly smaller in the prototype groups than in the FBS group (P = .02, P = .02). CONCLUSION: The efficacies of both prototype membranes were not inferior to that of the FBS membrane, indicating that they may facilitate bone regeneration and maturation when ß-TCP mixed with autologous blood is employed.


Assuntos
Regeneração Óssea , Substitutos Ósseos , Titânio , Animais , Fosfatos de Cálcio , Cães , Mandíbula , Membranas
14.
Chemosphere ; 237: 124517, 2019 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-31549644

RESUMO

The dye wastewater treatment by membrane separation technology has obtained extensive attention in recent years. Nevertheless, it was rare for research on the removal of differently charged mixed dyes. In this study, several UiO-66-NH2 composite membranes were prepared and optimization experiments were conducted. The performance of composite membranes were evaluated by the removal of cationic (Methylene blue, MB), neutral (Rhodamine B, RB), and anionic (Congo red, CR) dyes. The optimization results demonstrated that the UiO-66-NH2/graphene oxide (UNG) composite membrane (PUF/PDA/UNG) which was loaded on polyurethane foam modified with polydopamine (PUF/PDA) had the best properties. In filtration experiments, the solution pH exhibited greater effect on the removal efficiency of MB and CR than RB. When NaCl, KCl, CaCl2 and Na2SO4 coexisted in the dye solution, the removal efficiency of MB by PUF/PDA/UNG membrane were 96.62%, 98.17%, 86.39% and 99.34% respectively. The presence of humic acid showed slight inhibitory effect on the removal of MB by PUF/PDA/UNG membrane (71.93%). The experimental results for mixed dyes filtration showed that PUF/PDA/UNG membrane could effectively remove MB, RB and CR in binary (i.e., MB/RB and RB/CR) and ternary (i.e., MB/RB/CR) systems through secondary filtration. And PUF/PDA/UNG membrane could remove MB and CR simultaneously through one-time filtration in MB/CR binary system. The removal mechanism was mainly attributed to the aggregation of mixed dyes, electrostatic interaction between dye molecules and the membrane surface, and hydrogen bonding. All results suggested that the as-prepared PUF/PDA/UNG membrane have great potential in practical treatment of dye wastewater.


Assuntos
Corantes/química , Grafite/química , Eliminação de Resíduos Líquidos , Poluentes Químicos da Água/química , Adsorção , Filtração , Indóis , Membranas , Azul de Metileno , Polímeros , Poliuretanos , Rodaminas , Águas Residuárias
15.
Mater Sci Eng C Mater Biol Appl ; 104: 109944, 2019 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-31500058

RESUMO

Anti-relapse therapy after surgery plays a critical role in cancer therapy. New strategies maximizing the delivery of drugs to tumor cells while reducing toxic side effects on normal tissues and organs are still urgently required. In order to solve the problems of the poor delivery and inadequate distribution of cytotoxic chemotherapeutic drugs in the clinical application, an ultrasound-controllable and implantable release-system that utilized waterborne polyurethane (WPU) and chitosan (CS) composite membrane as drug carrier with wide flexible loading capacity for doxorubicin (DOX) was described in present work. Benefiting from the hydrophilic segment in WPU and bioactivity of amino groups on side chains of CS, the resulting composite films exhibited fine biodegradability, favorable cytocompatibility and excellent blood compatibility. The in vitro release studies illustrated that the drug-loading membranes displayed a well sustained release effect manifested in slow release, stability and no sudden release, and the DOX was able to release in an ultrasound-controlled manner. Cellular uptake assay and CCK 8 assay showed that the DOX can be released efficiently from the drug-loading matrix and taken up by tumor cells. As a means of adjuvant local treatment, this work provided a facile approach to the design of ultrasound-regulated membrane matrix that is highly beneficial not only due to the higher and long-term therapeutic efficiency, and improvement of utilization efficiency of chemotherapeutic drugs but also the low toxicity to normal cells.


Assuntos
Antineoplásicos/química , Quitosana/química , Poliuretanos/química , Animais , Antineoplásicos/farmacologia , Linhagem Celular , Linhagem Celular Tumoral , Doxorrubicina/química , Doxorrubicina/farmacologia , Portadores de Fármacos/química , Sistemas de Liberação de Medicamentos/métodos , Liberação Controlada de Fármacos , Membranas/química , Camundongos , Nanopartículas/química , Ondas Ultrassônicas
16.
Ecotoxicol Environ Saf ; 184: 109618, 2019 Nov 30.
Artigo em Inglês | MEDLINE | ID: mdl-31487569

RESUMO

Photocatalytic membrane coupled to biodegradation offers potential for degrading volatile organic compounds (VOCs) in photocatalytic membrane biofilm reactor. An intimately coupled photocatalysis and biodegradation reactor was operated in continuous operation for 500 days to treat simulated waste gas containing toluene. Toluene removal efficiency obtained 99%, with the elimination capacity of 550 g m-3·h-1. Membrane photocatalysis coupled to biodegradation was created to improve toluene removal from 11 to 20%. The dominant genera were Lysinibacillus, Hydrogenophaga, Pseudomonas at 30 d, Rudaea, Dongia, Litorilinea at 230 d xyl, Tod, Tcb, Bed, Tmo, Tbu, Tou, Dmp, Cat were functional genes of toluene metabolism, as shown by16S rDNA and metagenomic sequencing. Photocatalysis destroyed part of the toluene into biodegradable intermediates that were immediately mineralized by microorganisms in biofilm, some toluene was directly degraded by toluene degrading bacterial community into carbon dioxide and water. The novel hybrid photocatalytic membrane biofilm reactor is a cost-effective and robust alternative to VOCs treatment.


Assuntos
Reatores Biológicos/microbiologia , Consórcios Microbianos/fisiologia , Tolueno/metabolismo , Bactérias/classificação , Bactérias/genética , Bactérias/metabolismo , Biodegradação Ambiental , Biofilmes , Membranas , Oxirredução , Processos Fotoquímicos , Tolueno/isolamento & purificação , Compostos Orgânicos Voláteis/isolamento & purificação , Compostos Orgânicos Voláteis/metabolismo
17.
Eur J Pharm Biopharm ; 145: 1-6, 2019 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-31560955

RESUMO

Both Gram-positive and Gram-negative bacteria can release nano-sized lipid bilayered structures, known as membrane vesicles (MVs). These MVs play an important role in bacterial survival by orchestrating interactions between bacteria and between bacteria and host. The major constituents of MVs are proteins, lipids and nucleic acids. Due to the immunogenicity of the membrane lipids and/or proteins of the MVs, in combination with adjuvant danger signals and the repeating patterns on the nanosized surface, MVs can effectively stimulate the innate and adaptive immune system. Since they are non-replicating, they are safer than attenuated vaccines. In addition, by genetic engineering of the donor cells, further improvements to their safety profile, immunogenicity and yield can be achieved. To date, one MV-based vaccine against Neisseria meningitidis (N. meningitidis) serogroup B was approved. Other (engineered) MVs in the pipeline study are mostly in the preclinical phase.


Assuntos
Bactérias/imunologia , Bicamadas Lipídicas/imunologia , Lipídeos de Membrana/imunologia , Membranas/imunologia , Vacinas/imunologia , Imunidade Adaptativa/imunologia , Adjuvantes Imunológicos , Animais , Formação de Anticorpos/imunologia , Proteínas de Bactérias/imunologia , Humanos
18.
Environ Sci Technol ; 53(20): 11869-11876, 2019 Oct 15.
Artigo em Inglês | MEDLINE | ID: mdl-31545033

RESUMO

Concentration polarization (CP) occurs in almost all membrane-based separation processes. In this study, the concentration profile of the dissolved salt has been accurately characterized using a previously developed laser-based spectrophotometric method which had a spatial resolution of 4.5 µm. The objective of the current work was to probe the concentration profile of the solute and analyze the impact of operating parameters, such as feed concentration, hydrodynamic conditions, and feed temperature, on the solute concentration profile in the boundary layer. This study also examined the validity of the conventional approach, where semi-empirical models are used to estimate the boundary layer thickness (BLT) and concentration polarization coefficient (CPC)-based on experimental results. Nusselt correlations were developed specifically for the membrane cell and validated through experimental observations at the operating conditions used in this study. A key finding of this study is that the conventional approach of estimating the effect of CP severely underpredicts the BLT and CPC. The results of this study highlight the need to develop new methods to estimate the BLT and CPC as the conventional approach of using semi-empirical Nusselt and Sherwood correlations does not agree with experimental observations obtained for a membrane distillation system employed in this study.


Assuntos
Destilação , Membranas Artificiais , Membranas , Soluções , Temperatura Ambiente
19.
Chemosphere ; 237: 124495, 2019 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-31394452

RESUMO

A regeneration method for porous electrospun membranes embedding alumina nanoparticles saturated with minocycline was investigated by UV-LED system. The percentage of adsorption capacities before and after regeneration were used to evaluate regeneration efficiency. The PVDF and PVDF-Al2O3 fiber mats were prepared by electrospinning technique. Scanning electron microscope (SEM), transmission electron microscope (TEM), energy-dispersive X-ray spectroscopy (EDS) analyses directly confirmed that Al2O3 nanoparticles were generally exposed to the surface of PVDF-Al2O3 fiber mats. Among them, PVDF-Al2O3 10% fiber mats can effectively adsorb minocycline (remove efficiency >97% in 18 h) with first-order rate constant k = 2.253 ±â€¯0.331 h-1. The sorption capacity can still keep 81% after five sorption/UV-regeneration circulations. Two successional stages may exist during regeneration: (i) transfer of minocycline from the surface of PVDF-Al2O3 fibers to the DI water, followed by the (ii) decomposition of this compound in aqueous solution by direct and indirect photolysis to yield the intermediate species. The desorption capacity and desorption percentage were 4.39 mg g-1 and 23.30% respectively. The regeneration yields were further enhanced to 94.20% by UV radiation. Minocycline was effectively degraded to intermediate products by direct and indirect photolysis, further degraded into CO2, H2O, and NOx by UV-generated ozone during regeneration. The results indicated that UV radiation was an effective method of regenerating PVDF-Al2O3 fiber mats with low energy requirements. The photochemical byproducts and the reaction sites during regeneration were also determined and recognized.


Assuntos
Óxido de Alumínio/química , Minociclina/química , Nanopartículas/química , Adsorção , Membranas , Fotólise , Porosidade , Raios Ultravioleta , Água/química , Poluentes Químicos da Água/análise
20.
Med Sante Trop ; 29(2): 127-132, 2019 May 01.
Artigo em Inglês | MEDLINE | ID: mdl-31379336

RESUMO

The induced membrane technique is a simple and effective method for reconstructing bone defects in limbs. It is suited to low resource settings, if sufficient care is taken in preparing and performing the technique. Key points for the success of this procedure are described here. In austere environments, its use is mostly limited by possibilities for treatment of bone infection, but also by access to surgical cement and available bone stock. Alternatives for overcoming these last two obstacles are presented.


Assuntos
Doenças Ósseas/cirurgia , Transplante Ósseo/métodos , Osso e Ossos/lesões , Osso e Ossos/cirurgia , Regeneração Tecidual Guiada/métodos , Doenças Ósseas/microbiologia , Recursos em Saúde , Humanos , Membranas
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