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1.
Chemosphere ; 244: 125386, 2020 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-32050321

RESUMO

Polysulfone ultrafiltration (UF) and polypiperazine-amide nanofiltration (NF) membranes were first fabricated by phase inversion and interfacial polymerization, and then modified by the commonly used TiO2 on the membrane surface, respectively. Compared with the pristine UF and NF membranes, pure water flux decreased by 40.66% for modified UF membrane and 12.92% for modified NF membrane, while the contact angle of the modified membranes decreased from 66.5° to 35.3° for UF membrane and from 48.2° to37.7° for NF membrane. However, the membrane modified by TiO2 nanoparticles for both UF and NF membranes exhibited much better anti-fouling and separation performance for two types of oil-in-water emulsions with different droplet size (i.e., prepared oil-in-water emulsion with low salinity and oil produced water in Shengli oilfield, China). It was obvious that water flux of modified UF only slightly decreased and the stable water flux was 2.2 times and 15.6% higher than that of pristine membranes for the prepared oil-in-water emulsion and produced water, respectively. According to the five fouling models for UF, the TiO2 modified UF membrane could alleviate the fouling on membrane surface and greatly increase water flux by reducing the adsorption, deposition, blockage of membrane pores and formation of cake layer for two types of oil-in-water emulsion. For NF, water flux of the modified membrane increased by 66.1% and 22.8% for prepared oil-in-water emulsion and produced water, respectively. TiO2 coating effectively alleviated the oil adhesion and cake layer formation on the membrane surface.


Assuntos
Emulsões/química , Membranas Artificiais , Poluição por Petróleo , Piperazina/química , Polímeros/química , Sulfonas/química , Purificação da Água/métodos , China , Emulsões/isolamento & purificação , Óleos Industriais , Nanopartículas , Campos de Petróleo e Gás , Ultrafiltração/métodos , Ultrafiltração/normas
2.
Food Chem ; 313: 126154, 2020 May 30.
Artigo em Inglês | MEDLINE | ID: mdl-31931425

RESUMO

The aim of this study was to develop a scalable crossflow diafiltration/ultrafiltration procedure for quinoa 11S globulin purification starting at the bench scale using Ultra15 centrifugal filter devices. The electrophoretic profiles of centrifugal ultrafiltration fractions showed a high heterogeneity in the bands, while crossflow ultrafiltration reduced the phenomena of protein sticking to the membrane, avoiding aggregate formation. In the crossflow protein concentration, flux decline curves were studied according to Hermia's fouling mechanisms and the resistance in a series model. High reversible resistance was related to external mechanisms due to complete blockage of the membrane surface followed by cake formation. The crossflow ultrafiltration was the most efficient technique for obtaining 57 kDa chenopodin isolate with higher processing capacity, purity and protein yield. The diafiltration/ultrafiltration process proved to be adequate and easy to handle to scale up the production of the 11S quinoa globulin.


Assuntos
Proteínas de Plantas/isolamento & purificação , Ultrafiltração/métodos , Centrifugação/métodos , Extratos Vegetais/química , Extratos Vegetais/isolamento & purificação , Ultrafiltração/instrumentação
3.
Chemosphere ; 240: 124940, 2020 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-31574446

RESUMO

Charged ultrafiltration (UF) membranes can repel electrically charged molecules that are smaller than the size of the membrane pores and display high rejection of solutes, high flux, and low operation pressures compared to uncharged UF, nanofiltration (NF) and reverse osmosis (RO). Here, a charged UF membrane composite (PANI/PVDF) was prepared and regulated via electrochemically reversible control in portions of amine/imine functional groups of PANI. As a result, the permeability and rejection ratios of CR2- on charged PANI/PVDF, with PVDF as a control, increased from 19.6 to a maximum of 183.3 L m-2 h-1 bar-1 and from 3.4% to 74%, which expands the trade-off confine benefited from surface potential change from -12.21 mV to -25.26 mV, furtherly, the rejection ratio of CR2- on PANI/PVDF reached up to 93% via the electrochemical regulation. Finally, a fixed-charge model was built that well describes the steric and electric repulsion effects on membrane performance and the important roles of the electrochemically controllable surface charge. Moreover, the contour map of rejection ratios containing the ratio of molecular size vs the average pore size of the membrane (r/R = 0.2-1.0) and the zeta potential (-10 to -60 mV) were taken into account, which can be used to visually understand the rejection performance of membranes. This model is also appropriate for varying molecular sizes and for molecules with different charges. Our work opens a new horizon for the design of electrochemically controllable charged membranes to remove charged compounds.


Assuntos
Corantes/análise , Técnicas Eletroquímicas/métodos , Ultrafiltração/métodos , Purificação da Água/métodos , Eletricidade , Membranas Artificiais , Propriedades de Superfície
4.
Chemosphere ; 238: 124659, 2020 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-31524612

RESUMO

A hybrid system was developed in this study consisting of different coagulation systems and ultrafiltration (UF). Property and effect of flocs formed in different coagulation systems on ultrafiltration membrane fouling control were investigated. All three coagulation systems, as pretreatment of UF, were effective in improving membrane flux and reducing membrane resistance within an appropriate range of natural organic matters (NOM) concentration. At high initial NOM concentration, the performance of polyaluminum chloride (PAC) on NOM removal and fouling control was severely limited. For PAC-poly dimethyl diallyl ammonium chloride (PAC-PolyDMDAAC) coagulation system, the limitation of initial NOM concentration on removing NOM and alleviating membrane fouling was slightly weakened, indicating composite flocculant PAC-PolyDMDAAC produced larger flocs through combined action of charge neutralization and adsorption bridging. In PAC + PolyDMDAAC dual coagulation system, the combined action of adsorption-bridging effect, sweeping effect, and charge neutralization were the mechanisms under both low and high initial NOM concentration. Although the flocs formed in PAC + PolyDMDAAC dual coagulation system had poor recovery ability compared with those formed in PAC and PAC-PolyDMDAAC coagulation system, flocs formed through adsorption-bridging and sweeping had large size and higher ability to resist shear force, resulting in the formation of cake layer with porous and fluffy structure and less blockage in membrane pore in PAC + PolyDMDAAC dual coagulation system. These results demonstrated that dual coagulation system combined PAC coagulation and PolyDMDAAC flocculation as a pretreatment of UF process can improve the characteristics of flocs and structure of cake layer for improving NOM removal and controlling membrane fouling.


Assuntos
Hidróxido de Alumínio , Membranas Artificiais , Ultrafiltração/métodos , Adsorção , Floculação , Ultrafiltração/instrumentação , Purificação da Água/métodos
5.
Heart Fail Clin ; 16(1): 81-97, 2020 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-31735318

RESUMO

Abnormal fluid handling leads to physiologic abnormalities in multiple organ systems. Deranged hemodynamics, neurohormonal activation, excessive tubular sodium reabsorption, inflammation, oxidative stress, and nephrotoxic medications are important drivers of harmful cardiorenal interactions in patients with heart failure. Accurate quantitative measurement of fluid volume is vital to individualizing therapy for such patients. Blood volume analysis and pulmonary artery pressure monitoring seem the most reliable methods for assessing fluid volume and guiding decongestive therapies. Still the cornerstone of decongestive therapy, diuretics' effectiveness decreases with progression of heart failure. Extracorporeal ultrafiltration, an alternative to diuretics, has been shown to reduce heart-failure events.


Assuntos
Síndrome Cardiorrenal/etiologia , Diuréticos/uso terapêutico , Insuficiência Cardíaca/complicações , Hemodinâmica/fisiologia , Ultrafiltração/métodos , Síndrome Cardiorrenal/terapia , Progressão da Doença , Insuficiência Cardíaca/fisiopatologia , Insuficiência Cardíaca/terapia , Humanos
6.
J Water Health ; 17(6): 910-920, 2019 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-31850898

RESUMO

Antibiotic resistance genes (ARGs), as emerging environmental contaminants, are becoming a threat to human health. In this study, the combined processes of powdered activated carbon (PAC)/biological PAC (BPAC)-ultrafiltration (UF) were adopted to reduce the levels of ARGs in secondary effluents from a wastewater treatment plant. The removal of dissolved organic carbon (DOC) and the change of normalized flux in the UF process were investigated. In addition, the structural characteristics of the microorganisms of the BPAC were analyzed. The results showed that the appropriate dosage of PAC and BPAC was 40 mg/L. At this dosage, PAC/BPAC-UF combined processes could effectively remove the ARGs in secondary effluents by 1.26-2.69-log and 1.55-2.97-log, respectively; and the removal rates of DOC would be 60.7% and 54.1%, respectively. Relative to the direct UF, the membrane fluxes of the two combined processes were increased by 15.6% and 25.1%, respectively. Significant removal correlations were found between ARGs, intI1, DOC and 16SrDNA. These results revealed that the PAC/BPAC-UF combined process might play a promising role in ARG reduction in secondary effluents from wastewater treatment plants.


Assuntos
Antibacterianos/análise , Carvão Vegetal/química , Resistência Microbiana a Medicamentos/genética , Genes Bacterianos , Ultrafiltração/métodos , Poluentes Químicos da Água/análise , Purificação da Água/métodos , Adsorção , Biodegradação Ambiental , Incrustação Biológica/prevenção & controle , Humanos , Membranas Artificiais , Pós , Águas Residuárias/química , Águas Residuárias/microbiologia
7.
Environ Sci Pollut Res Int ; 26(36): 36296-36307, 2019 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-31713819

RESUMO

Cake formed by flocs is a crucial factor to affect membrane fouling during coagulation-ultrafiltration process. To investigate the role of floc properties on cake, cake characteristics under various coagulant dosage conditions were calculated by scanning electron microscope (SEM) imaging. Results found that one SEM image with × 5000 magnification could accurately estimate cake porosity with relative error lower than 5.00% for all conditions, whereas more SEM images with × 10,000 magnification or × 20,000 magnification should be applied to calculate cake porosity precisely. This could be explained by different pore information of SEM images with various magnifications. Compared to single SEM image with × 10,000 magnification and × 20,000 magnification, single SEM image with × 5000 magnification contained the most comprehensive pore information and slightly overestimated pore area for pore smaller than 0.4 µm2 due to lower resolution. To verify feasibility by SEM image evaluating cake characteristics, cake porosity calculated by SEM image and Carman-Kozeny equation were analyzed. The results showed that cake porosity estimated by these two methods were nearly the same, proving the feasibility of this method. Moreover, with the increase of coagulant dosage, cake porosity presented similar variation with floc average size, indicating that floc average size was likely to dominate cake porosity in this study. For pore characteristics, pore average characteristic length and pore average area were in accordance with floc fractal dimension, whereas pore fractal dimension and pore amount were consistent with floc average size. This gives specific information about the relation between floc properties and cake characteristics.


Assuntos
Floculação , Microscopia Eletrônica de Varredura , Ultrafiltração/métodos , Incrustação Biológica/prevenção & controle , Coagulantes/análise , Fractais , Membranas Artificiais , Porosidade , Ultrafiltração/instrumentação
8.
BMC Neurol ; 19(1): 252, 2019 Oct 25.
Artigo em Inglês | MEDLINE | ID: mdl-31653203

RESUMO

BACKGROUND: Progressive multifocal leukoencephalopathy (PML) is a demyelinating disorder caused by JC virus (JCV). Although detecting JCV DNA in the cerebrospinal fluid (CSF) by real-time polymerase chain reaction (PCR) is useful, diagnosis is difficult when JCV concentrations are low. We therefore aimed to lower the detection limit of real-time PCR testing by enriching JCV in the CSF via ultrafiltration. METHODS: Virus suspensions and CSF specimens from 20 untreated patients with suspected PML were collected and total DNAs were extracted. The JCV large T gene was detected by quantitative real-time PCR under condition with and without prior centrifugal ultrafiltration. RESULTS: The JCV DNA was reliably detected to a lower limit of 10 copies/mL of virus suspension by real-time PCR with ultrafiltration. When using this method, the quantity of JCV DNA per PCR reaction increased 3.2- to 8.7-fold compared with the standard procedure. Seven patients were positive for JCV when using the standard procedure, and an additional patient was positive when using ultrafiltration. All JCV-positive patients had neurological features and magnetic resonance imaging findings compatible with PML. CONCLUSIONS: The detection limit of JCV DNA by real-time PCR can be lowered by viral enrichment using ultrafiltration. Our simple protocol offers a valuable tool for PML diagnosis when extremely low copy numbers of JCV are released into the CSF or when brain biopsy is not feasible.


Assuntos
DNA Viral/líquido cefalorraquidiano , Vírus JC/isolamento & purificação , Leucoencefalopatia Multifocal Progressiva/diagnóstico , Reação em Cadeia da Polimerase em Tempo Real/métodos , Ultrafiltração/métodos , Adulto , Feminino , Humanos , Leucoencefalopatia Multifocal Progressiva/líquido cefalorraquidiano , Masculino , Pessoa de Meia-Idade
9.
Mar Drugs ; 17(9)2019 Sep 12.
Artigo em Inglês | MEDLINE | ID: mdl-31547415

RESUMO

For the full use of Spanish mackerel (Scomberomorous niphonius) muscle to produce antioxidant peptides, the proteins of Spanish mackerel muscle were separately hydrolyzed under five kinds of enzymes and in vitro gastrointestinal digestion, and antioxidant peptides were isolated from the protein hydrolysate using ultrafiltration and multiple chromatography methods. The results showed that the hydrolysate (SMPH) prepared using in vitro GI digestion showed the highest degree of hydrolysis (27.45 ± 1.76%) and DPPH radical scavenging activity (52.58 ± 2.68%) at the concentration of 10 mg protein/mL among the six protein hydrolysates, and 12 peptides (SMP-1 to SMP-12) were prepared from SMPH. Among them, SMP-3, SMP-7, SMP-10, and SMP-11 showed the higher DPPH radical scavenging activities and were identified as Pro-Glu-Leu-Asp-Trp (PELDW), Trp-Pro-Asp-His-Trp (WPDHW), and Phe-Gly-Tyr-Asp-Trp-Trp (FGYDWW), and Tyr-Leu-His-Phe-Trp (YLHFW), respectively. PELDW, WPDHW, FGYDWW, and YLHFW showed high scavenging activities on DPPH radical (EC50 1.53, 0.70, 0.53, and 0.97 mg/mL, respectively), hydroxyl radical (EC50 1.12, 0.38, 0.26, and 0.67 mg/mL, respectively), and superoxide anion radical (EC50 0.85, 0.49, 0.34, and 1.37 mg/mL, respectively). Moreover, PELDW, WPDHW, FGYDWW, and YLHFW could dose-dependently inhibit lipid peroxidation in the linoleic acid model system and protect plasmid DNA (pBR322DNA) against oxidative damage induced by H2O2 in the tested model systems. In addition, PELDW, WPDHW, FGYDWW, and YLHFW could retain their high activities when they were treated under a low temperature (<60 °C) and a moderate pH environment (pH 5-9). These present results indicate that the protein hydrolysate, fractions, and isolated peptides from Spanish mackerel muscle have strong antioxidant activity and might have the potential to be used in health food products.


Assuntos
Antioxidantes/farmacologia , Produtos Pesqueiros , Peptídeos/farmacologia , Perciformes , Hidrolisados de Proteína/química , Animais , Antioxidantes/química , Antioxidantes/isolamento & purificação , Fracionamento Químico/métodos , Cromatografia/métodos , Peroxidação de Lipídeos/efeitos dos fármacos , Músculos/química , Estresse Oxidativo/efeitos dos fármacos , Peptídeos/química , Peptídeos/isolamento & purificação , Estabilidade Proteica , Ultrafiltração/métodos
10.
J Agric Food Chem ; 67(44): 12237-12244, 2019 Nov 06.
Artigo em Inglês | MEDLINE | ID: mdl-31560847

RESUMO

Human milk oligosaccharides (HMOs) maintain and promote infant health. Most of the current methods for HMOs quantitation require labor-intensive and time-consuming steps for sample preparation. This study presents two very simple and easy-to-operate pretreatment methods, requiring either ultrafiltration or centrifugation to separate free oligosaccharides from whole fat human milk and other milk matrix before oligosaccharides labeling for quantifying HMOs using ultrahigh pressure liquid chromatography with fluorescence detection. A single chromatography run quantified 15 sialylated and neutral HMOs with high sensitivity (with an LOD less than 8 pg for all HMOs tested: about 1 pg for 2'-fucosyllactose, 3-fucosyllactose, 4'-galactosyllactose, 3'-galactosyllactose, and 6'-galactosyllactose) and good linearity with coefficient of correlation above 0.999. Accuracy and precision were satisfactory for both pretreatment methods. Overall, the centrifugation pretreatment was efficient and reliable for samples with high levels of oligosaccharides, and the ultrafiltration pretreatment was especially suitable for samples with low oligosaccharide abundance.


Assuntos
Centrifugação/métodos , Leite Humano/química , Oligossacarídeos/análise , Oligossacarídeos/isolamento & purificação , Ultrafiltração/métodos , Cromatografia Líquida de Alta Pressão/instrumentação , Cromatografia Líquida de Alta Pressão/métodos , Feminino , Humanos
11.
J Chromatogr Sci ; 57(9): 838-846, 2019 Oct 17.
Artigo em Inglês | MEDLINE | ID: mdl-31504273

RESUMO

There is an increasing interest in screening and developing natural tyrosinase inhibitors widely applied in medicinal and cosmetic products, as well as in the food industry. In this study, an approach by ultrafiltration LC-MS and molecular docking was used to screen and identify tyrosinase inhibitors from Semen Oroxyli extract. The samples were first incubated with the tyrosinase to select the optimal binding conditions including tyrosinase concentration, incubation time and the molecular weight of ultrafiltration membrane. By comparison of the chromatographic profiles of the extracts after ultrafiltration with activated and inactivated tyrosinase, the potential inhibitors were obtained and then identified by LC-MS. The relative binding affinities of the potential inhibitors were also calculated based on the decrease of peak areas of those. As a result, seven compounds were fished out as tyrosinase inhibitors by this assay. Among them, oroxin A and baicalein showed higher tyrosinase inhibitory than resveratrol as positive drug, and their binding mode with enzyme was further verified via the molecular docking analysis. The test results showed that the proposed method was a simple, rapid, effective, and reliable method for the discovery of natural bioactive compounds, and it can be extended to screen other bioactive compounds from traditional Chinese medicines.


Assuntos
Bignoniaceae , Descoberta de Drogas/métodos , Inibidores Enzimáticos , Monofenol Mono-Oxigenase/antagonistas & inibidores , Extratos Vegetais , Cromatografia Líquida de Alta Pressão/métodos , Inibidores Enzimáticos/análise , Inibidores Enzimáticos/química , Inibidores Enzimáticos/metabolismo , Flavonas/análise , Flavonas/química , Flavonas/metabolismo , Glucosídeos/análise , Glucosídeos/química , Glucosídeos/metabolismo , Espectrometria de Massas/métodos , Simulação de Acoplamento Molecular/métodos , Monofenol Mono-Oxigenase/química , Monofenol Mono-Oxigenase/metabolismo , Extratos Vegetais/análise , Extratos Vegetais/química , Extratos Vegetais/metabolismo , Ultrafiltração/métodos
12.
J Cardiothorac Surg ; 14(1): 163, 2019 Sep 10.
Artigo em Inglês | MEDLINE | ID: mdl-31500645

RESUMO

BACKGROUND: Zero balance ultrafiltration (Z-BUF) utilizing injectable 8.4% sodium bicarbonate is utilized to treat hyperkalemia and metabolic acidosis associated with cardiopulmonary bypass (CPB). The nationwide shortage of injectable 8.4% sodium bicarbonate in 2017 created a predicament for the care of cardiac surgery patients. Given the uncertainty of availability of sodium bicarbonate solutions, our center pro-actively sought a solution to the sodium bicarbonate shortage by performing Z-BUF with dialysate (Z-BUF-D) replacement fluid for patients undergoing cardiopulmonary bypass. METHODS: Single-center, retrospective observational evaluation of the first 46 patients at an academic medical center who underwent Z-BUF using dialysate over a period of 150 days with comparison of these findings to a historical group of 39 patients who underwent Z-BUF with sodium chloride (Z-BUF-S) over the preceding 150 days. The primary outcome was the change in whole blood potassium levels pre- and post-Z-BUF-D. Secondary outcomes included changes in pre- and post-Z-BUF-D serum bicarbonate levels and the amount of serum bicarbonate used in each Z-BUF cohort (Z-BUF-D and Z-BUF-S). RESULTS: Z-BUF-D and Z-BUF-S both significantly reduced potassium levels during CPB. However, Z-BUF-D resulted in a significantly decreased need for supplemental 8.4% sodium bicarbonate administration during CPB (52 mEq ± 48 vs. 159 mEq ± 85, P < 0.01). There were no complications directly attributed to the Z-BUF procedure. CONCLUSION: Z-BUF with dialysate appears to be analternative to Z-BUF with sodium chloride with marked lower utilization of intravenous sodium bicarbonate.


Assuntos
Acidose/terapia , Bicarbonatos/provisão & distribução , Ponte Cardiopulmonar/efeitos adversos , Soluções para Diálise/provisão & distribução , Complicações Pós-Operatórias/terapia , Ultrafiltração/métodos , Bicarbonatos/farmacologia , Soluções para Diálise/farmacologia , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Estudos Retrospectivos , Estados Unidos
13.
Chemosphere ; 237: 124859, 2019 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-31549667

RESUMO

Concentration polarization is an important issue in micellar enhanced ultrafiltration (MEUF) of wastewater containing heavy metal ions at low surfactant concentrations. In this paper, we studied removal of Cd(Ⅱ) by cross flow MEUF at low sodium dodecyl sulfate (SDS) concentration levels, and the role of concentration polarization in flux decline and Cd(Ⅱ) rejection was emphasized. Concentration polarization resistance and SDS concentration near membrane were calculated to characterize concentration polarization. The results showed that SDS concentration near membrane was 13 mM when feed concentration was merely 0.8 mM. By combining phase diagram of SDS, structures of SDS micelles in concentration polarization layer were deduced and thin layer structure transformed to porous structure formed by accumulated globular micelles when SDS concentration increased. Although micelles formed in concentration polarization layer was responsible for flux decline, they also provided adsorption sites for Cd(Ⅱ).


Assuntos
Cádmio/isolamento & purificação , Ultrafiltração/métodos , Águas Residuárias/química , Adsorção , Membranas Artificiais , Metais Pesados , Micelas , Dodecilsulfato de Sódio/química , Tensoativos/química , Ultrafiltração/instrumentação
14.
Environ Sci Pollut Res Int ; 26(31): 31623-31631, 2019 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-31482524

RESUMO

A lab-scale unit of the hybrid continuous stirred tank reactor (CSTR) adsorption/ultrafiltration (UF) system was used to evaluate the removal efficiency of silica from brackish water. The semi-batch adsorption process was carried out using iron oxy/hydroxide agglomerates (IOAs) as adsorbent and hollow fiber ultrafiltration membrane as a barrier to the adsorbent passage to the product water. The effect of residence time, concentration of silica, and adsorbent dosage on the silica removal and UF membrane blockage was examined. It was found that a short residence time of 15 min was sufficient to achieve the maximum adsorption capacity similar to that obtained in batch isotherm experiments. The adsorption capacity increased with the augmentation of the silica concentration and decreased with the increase in the adsorbent dosage. The UF was effectively employed to separate the loaded adsorbent without fouling the membrane until breakthrough. A simple model was applied to accurately predict the adsorption breakthrough curves.


Assuntos
Águas Salinas/análise , Dióxido de Silício/análise , Ultrafiltração/métodos , Adsorção , Águas Salinas/química , Dióxido de Silício/química , Água , Purificação da Água
15.
J Dairy Sci ; 102(10): 8756-8767, 2019 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-31421884

RESUMO

Proteinaceous matter can leak into the permeate stream during ultrafiltration (UF) of milk and whey and lead to financial losses. Although manufacturers can measure protein content in the finished permeate powders, there is currently no rapid monitoring tool during UF to identify protein leak. This study applied front-face fluorescence spectroscopy (FFFS) and chemometrics to identify the fluorophore of interest associated with the protein leak, develop predictive models to quantify true protein content, and classify the types of protein leak in permeate streams. Crude protein (CP), nonprotein nitrogen (NPN), true protein (TP), tryptone-equivalent peptide (TEP), α-lactalbumin (α-LA), and ß-lactoglobulin (ß-LG) contents were measured for 37 lots of whey permeate and 29 lots of milk permeate from commercial manufacturers. Whey permeate contained more TEP than did milk permeate, whereas milk permeate contained more α-LA and ß-LG than did whey permeate. The types of protein leak were thus identified for predictive model development. Based on excitation-emission matrix (EEM) of high- and low-TP permeates, tryptophan excitation spectra were collected for predictive model development, measuring TP content in permeate. With external validation, a useful model for quality control purposes was developed, with a root mean square error of prediction of 0.22% (dry basis) and a residual prediction deviation of 2.8. Moreover, classification models were developed using partial least square discriminant analysis. These classification methods can detect high TP level, high TEP level, and presence of α-LA or ß-LG with 83.3%, 84.8%, and 98.5% cross-validated accuracy, respectively. This method showed that FFFS and chemometrics can rapidly detect protein leaks and identify the types of protein leak in UF permeate. Implementation of this method in UF processing plants can reduce financial loss from protein leaks and maintain high-quality permeate production.


Assuntos
Proteínas do Leite/análise , Leite/química , Proteínas do Soro do Leite/análise , Soro do Leite/química , Animais , Lactalbumina/análise , Lactoglobulinas/análise , Análise dos Mínimos Quadrados , Pós/análise , Espectrometria de Fluorescência , Ultrafiltração/métodos
16.
Mar Drugs ; 17(8)2019 Aug 08.
Artigo em Inglês | MEDLINE | ID: mdl-31398788

RESUMO

Angiotensin-I-converting enzyme (ACE) inhibitory peptides derived from natural products have shown a blood pressure lowering effect with no side effects. In this study, two novel ACE inhibitory peptides (His-Leu-His-Thr, HLHT and Gly-Trp-Ala, GWA) were purified from pearl oyster (Pinctada fucata martensii) meat protein hydrolysate with alkaline protease by ultrafiltration, polyethylene glycol methyl ether modified immobilized metal ion affinity medium, and reverse-phase high performance liquid chromatography. Both peptides exhibited high ACE inhibitory activity with IC50 values of 458.06 ± 3.24 µM and 109.25 ± 1.45 µM, respectively. Based on the results of a Lineweaver-Burk plot, HLHT and GWA were found to be non-competitive inhibitor and competitive inhibitor respectively, which were confirmed by molecular docking. Furthermore, the pearl oyster meat protein hydrolysate exhibited an effective antihypertensive effect on SD rats. These results conclude that pearl oyster meat protein is a potential resource of ACE inhibitory peptides and the purified peptides, HLHT and GWA, can be exploited as functional food ingredients against hypertension.


Assuntos
Inibidores da Enzima Conversora de Angiotensina/química , Inibidores da Enzima Conversora de Angiotensina/farmacologia , Peptídeos/química , Peptídeos/farmacologia , Peptidil Dipeptidase A/metabolismo , Pinctada/química , Hidrolisados de Proteína/química , Animais , Anti-Hipertensivos/química , Anti-Hipertensivos/farmacologia , Cromatografia Líquida de Alta Pressão/métodos , Hipertensão/tratamento farmacológico , Masculino , Carne , Simulação de Acoplamento Molecular , Pinctada/metabolismo , Hidrolisados de Proteína/metabolismo , Ratos , Ratos Sprague-Dawley , Ultrafiltração/métodos
17.
Chemosphere ; 237: 124398, 2019 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-31376692

RESUMO

The goal of this study was to identify the scaling from the chemical cleaning of a polyvinylidene fluoride (PVDF) membrane, fouled by treating a solution containing inorganic foulants (Al, Fe, and Mn) in the presence of kaolin and humic acid as a natural organic matter at Ca+2 strength of 0.5 mMole. Chemical cleaning of the membrane was conducted using solutions prepared in deionized water and permeate water (PW), and the accumulation of insoluble salts on the membrane during cleaning were evaluated. Energy dispersive spectroscopy analysis was used to verify the presence inorganic foulants, and field emission scanning electron microscopy confirmed the changes in membrane symmetry from the accumulation of the foulants. A Fourier-transformed infrared spectroscopy analysis indicated the presence of new functional groups, i.e., C-Cl and C-O with bond vibrations at 542 cm -1 and 1,026 cm-1, respectively, on the membrane surface. The adsorbed mass of HA in the presence of inorganic foulants decreased from 3.54 ±â€¯0.045 mg to 2.24 ±â€¯0.095 mg and 1.71 ±â€¯0.075 mg, and the flux recoveries decreased from 93.2% to 85.69% and 81.92%, for the pristine to chemically DI and PW cleaned membrane, respectively. However, the membrane characterization results confirmed that Al was the major contributor to the accumulation of inorganic salts on the membrane during chemical cleaning and its role was more severe in the presence of Mn. The fitting results of Hermia's fouling models and a specific fouling analysis confirmed the contribution of complete blocking model with increase in irreversible fouling was observed after chemical cleaning.


Assuntos
Incrustação Biológica , Membranas Artificiais , Purificação da Água/métodos , Adsorção , Substâncias Húmicas/efeitos adversos , Teste de Materiais/métodos , Microscopia Eletrônica de Varredura , Espectroscopia de Infravermelho com Transformada de Fourier , Ultrafiltração/métodos , Poluentes da Água/isolamento & purificação
18.
Sci Total Environ ; 691: 322-331, 2019 Nov 15.
Artigo em Inglês | MEDLINE | ID: mdl-31323577

RESUMO

A detailed comparison of sand filtration (SF) and ultrafiltration (UF) was conducted in this study with the aim to provide systematic support for alternative UF and SF technologies. The results of natural organic matter (NOM) removal indicated that SF conferred a slightly higher removal rate for UV-absorbing compounds, humic-like substances and protein-like substances than UF, with removal efficiencies of 21.9%, 19.8% and 26.1%, respectively. In addition, SF and UF exhibited different removal performances for organic fractions: UF better removed high molecular-weight (MW) organics, while SF exhibited higher removal of medium-MW organics. Furthermore, chlorine and chlorine dioxide were used as disinfectants to compare the different influences of SF and UF on disinfection by-product (DBP) formation. Unexpectedly, SF exhibited a better capacity for reducing the formation of chlorite than the UF process, with concentrations of 0.57 mg/L and 0.69 mg/L, respectively. Importantly, for the emergency scenario, e.g. seasonal algae pollution, the UF process achieved significantly higher removal of algae cells (98.7%) than SF due to size exclusion, indicating substantial resistance to algae load shocks. Therefore, these findings are beneficial for making practical decisions to adopt SF or UF technology in drinking water treatment plants.


Assuntos
Ultrafiltração/métodos , Poluentes Químicos da Água/análise , Purificação da Água/métodos , Desinfetantes/análise , Desinfecção , Água Potável/química , Membranas Artificiais
19.
Water Sci Technol ; 79(11): 2068-2078, 2019 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-31318344

RESUMO

A simple and efficient route was used to prepare an amphiphilic copolymer (poly(propylene glycol)-co-poly(ethylene glycol)-co-poly(propylene glycol)) (PPG-co-PEG-co-PPG) by one-pot polymerization reaction. This copolymer was used as the hydrophilic additive in preparation of poly(vinylidene fluoride) (PVDF) ultrafiltration membranes via immersion-precipitation process. Surface characteristics of the membranes were confirmed by contact angle measurements, zeta potential, attenuated total reflectance Fourier transform infrared spectroscopy, X-ray photoelectron spectroscopy, scanning electron microscopy and atomic force microscopy. During filtration experiments, the modified membranes showed better permeation and antifouling performances compared to PVDF membranes with bovine serum albumin, sodium alginate and yeast. After hydraulic stirring cleaning with deionized water, water flux recovery and rejection ratio of the modified membranes were higher than those of pristine PVDF membrane, and the flux recovery ratio was maximized at 94.29%. It was suggested that PPG-co-PEG-co-PPG copolymer was anchored in the PVDF membrane through the two hydrophobic ends of PPG blocks, while the hydrophilic intermediate of the PEG block segregated onto the membrane or pore surface during the membrane preparation process. The synthesized method of amphiphilic PPG-co-PEG-co-PPG copolymer paved a novel way to solve the problems of less compatibility between the copolymer and membrane matrix and instability with water molecules in the ultrafiltration process.


Assuntos
Membranas Artificiais , Ultrafiltração/métodos , Permeabilidade , Polivinil
20.
Chemosphere ; 236: 124330, 2019 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-31319309

RESUMO

Shear-induced dissociation coupling with ultrafiltration (SID-UF) is an efficient and environment-friendly technology for the separation of heavy metal ions. In this paper, SID-UF was successfully employed for the selective recovery of nickel, zinc and copper from electroplating effluent using poly (acrylic acid) sodium (PAAS) and copolymer of maleic acid and acrylic acid (PMA) as complexants, respectively. The effects of the pH, mass ratio of polymer to metal ions (P/M) and the rotating speed on the metals removal efficiency are discussed in detail. The shear stabilities of the polymer-metal complexes were explored and the complexes critical shear rates (γc) were calculated. The results show that the order of the shear stabilities of PAA-metal complex is PAA-Zn > PAA-Cu > PAA-Ni, and that of PMA-metal complex is PMA-Cu > PMA-Ni > PMA-Zn. In addition, the construction of the stable structures of complexes and the calculation of the energies of the frontier molecular orbital by density functional theory method further predict and confirm the shear stabilities of the polymer-metal complexes.


Assuntos
Galvanoplastia/métodos , Metais Pesados/química , Ultrafiltração/métodos
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