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1.
Chemosphere ; 248: 126027, 2020 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-32032875

RESUMO

In this study, an activation treatment for recycled anion exchange membranes is proposed. Following the circular economy approach, these membranes were prepared by using end-of-life reverse osmosis membranes as mechanical support. The end-of-life membrane was previously used and discarded by desalination plants after overcoming its lifespan. The activation treatment was based on the subsequent immersion of the membranes in diluted acid and alkali solutions. This treatment promoted the complete dissociation of the functional groups in the membrane, making them more reactive to the counter ions. The effects of acid and alkali concentrations and exposition times on the electrochemical properties were studied and the best combination was selected. In such a way, a decrease of 37% in membrane electrical resistance was achieved. The performance of activated and non-activated membranes in brackish water desalination by electrodialysis was compared. The results showed that the proposed activation treatment increased the flux of fresh water more than four-fold (from 1.2 to 4.9 L h-1·m-2), with a considerable reduction of energy consumption (from 5.2 to 3.0 kWh·m-3) and a great improvement in current efficiency (from 38% to 71%). In conclusion, this work shows a simple and low cost methodology for the improvement of the electrochemical properties of recycled electromembranes and thus, their performance in electrodialysis.


Assuntos
Diálise/métodos , Purificação da Água/instrumentação , Diálise/instrumentação , Filtração/instrumentação , Água Doce , Concentração de Íons de Hidrogênio , Membranas Artificiais , Reciclagem , Purificação da Água/métodos
2.
J Sci Food Agric ; 100(1): 168-176, 2020 Jan 15.
Artigo em Inglês | MEDLINE | ID: mdl-31471909

RESUMO

BACKGROUND: Removing excessive naturally occurring fluoride from tea and/or infusions is difficult because the process has low efficiency and causes secondary pollution. In this study, a novel electrodialysis (ED) technology was developed. We examined the effect of crucial parameters (electrolyte concentration, operation voltage, ED duration and initial concentration of the tea infusion) on defluoridation performance using a highly efficient ion-exchange membrane with five-compartment cells. RESULTS: The most effective ED system results were obtained at an electrolyte concentration of 10 g kg-1 and operating voltage of 20 V. Moreover, the fluoride removal capacity (10.70-66.93%) was highly dependent on the ED duration (1-15 min) and initial concentration of the tea infusion (0.5-10 g kg-1 ). The longer the ED duration and the lower the initial concentration, the higher was the defluoridation performance. During ED, limited loss of the main inclusions (total polyphenols, catechins, caffeine and selected ions) was observed. Furthermore, the D201 anion resin-filled ED stack (0.5-5 g) and improvement of concentrate compartment electrolyte (≥5 times the dilute compartment electrolyte) in the ED system enhanced the defluoridation rate significantly. CONCLUSION: ED is a potentially effective method that can be used for defluoridation in the deep processing of tea products. © 2019 Society of Chemical Industry.


Assuntos
Diálise/métodos , Fluoretos/química , Manipulação de Alimentos/métodos , Chá/química , Diálise/instrumentação , Fluoretos/isolamento & purificação , Manipulação de Alimentos/instrumentação
3.
Pak J Pharm Sci ; 32(4): 1563-1570, 2019 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-31608875

RESUMO

Herbal remedies like the Thymus serpyllum L. is useful in traditional medicine for the treatment of many diseases especially congestion, and bronchitis. The purpose of this study was to formulate a micro-emulsion, a gel and an ointment containing the plant hydro distilled thymus oil extracted from Thymus serpyllum L. collected from Ziarat, Balochistan. The prepared formulations were subjected to in-vitro and ex vivo study release, High performance Liquid Chromatography (HPLC), Thin Layer Chromatography (TLC), to justify their suitability for topical use. The in-vitro and ex-Vivo release was studied using Franz Cells and using two different kinds of membrane synthetic dialysis cellulose membrane and natural rabbit skin and the amount of drug released was determined by HPLC at λ 274nm. The three formulations result obtained through dialysis cellulose membrane showed the faster release than the natural rabbit skin. However, the micro-emulsion, gel formulation showed the same release except ointment. The release from the above mentioned formulation can be arranged in the following descending order. micro-emulsion > Gel > Ointment. The best fit of release kinetics was achieved by Krosmeyer- Peppas, the TLC and HPLC identifies the Thymol, isolation and quantification of the marker. This study demonstrates that it is necessary to assess the impact of release and permeability pattern of different formulations. In vitro and ex-vivo diffusion cell experiments can be utilized to develop formulations of traditional medicines identifies.


Assuntos
Óleos Vegetais/administração & dosagem , Óleos Vegetais/farmacologia , Pele/efeitos dos fármacos , Thymus (Planta)/química , Administração Tópica , Animais , Celulose , Fracionamento Químico , Cromatografia Líquida de Alta Pressão , Cromatografia em Camada Delgada , Diálise/instrumentação , Diálise/métodos , Avaliação Pré-Clínica de Medicamentos/métodos , Liberação Controlada de Fármacos , Emulsões/química , Emulsões/farmacocinética , Géis/química , Géis/farmacocinética , Masculino , Membranas Artificiais , Permeabilidade , Óleos Vegetais/química , Óleos Vegetais/isolamento & purificação , Coelhos , Timol/análise , Timol/farmacocinética
4.
Nat Protoc ; 14(4): 1130-1168, 2019 04.
Artigo em Inglês | MEDLINE | ID: mdl-30903110

RESUMO

Among the different developed solid-state nanopores, nanopores constructed in a monolayer of molybdenum disulfide (MoS2) stand out as powerful devices for single-molecule analysis or osmotic power generation. Because the ionic current through a nanopore is inversely proportional to the thickness of the pore, ultrathin membranes have the advantage of providing relatively high ionic currents at very small pore sizes. This increases the signal generated during translocation of biomolecules and improves the nanopores' efficiency when used for desalination or reverse electrodialysis applications. The atomic thickness of MoS2 nanopores approaches the inter-base distance of DNA, creating a potential candidate for DNA sequencing. In terms of geometry, MoS2 nanopores have a well-defined vertical profile due to their atomic thickness, which eliminates any unwanted effects associated with uneven pore profiles observed in other materials. This protocol details all the necessary procedures for the fabrication of solid-state devices. We discuss different methods for transfer of monolayer MoS2, different approaches for the creation of nanopores, their applicability in detecting DNA translocations and the analysis of translocation data through open-source programming packages. We present anticipated results through the application of our nanopores in DNA translocations and osmotic power generation. The procedure comprises four parts: fabrication of devices (2-3 d), transfer of MoS2 and cleaning procedure (24 h), the creation of nanopores within MoS2 (30 min) and performing DNA translocations (2-3 h). We anticipate that our protocol will enable large-scale manufacturing of single-molecule-analysis devices as well as next-generation DNA sequencing.


Assuntos
Dissulfetos/química , Sequenciamento de Nucleotídeos em Larga Escala/métodos , Microtecnologia/métodos , Molibdênio/química , Nanoporos/ultraestrutura , Nanotecnologia/métodos , DNA/análise , DNA/genética , Diálise/instrumentação , Diálise/métodos , Sequenciamento de Nucleotídeos em Larga Escala/instrumentação , Humanos , Microtecnologia/instrumentação , Nanotecnologia/instrumentação , Imagem Individual de Molécula/instrumentação , Imagem Individual de Molécula/métodos
5.
Appl Biochem Biotechnol ; 187(1): 396-406, 2019 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-29961901

RESUMO

Preparation of xylonic acid from xylonate fermentation broth was studied in a four-chamber bipolar membrane electrodialysis (BMED) setup. The effects of metal-ion size, current density, and xylonate concentration on BMED were evaluated principally with respect to acid yield and partially with respect to efficiency and energy consumption. Sodium xylonate was more successful than potassium xylonate because of its smaller size and easier membrane penetrability for BMDE. Efficient electrodialysis was achieved using 50 mA/cm2 current density for 14 min; thus, we obtained 92% xylonic acid from 100 g/L sodium xylonate fermentation broth. In conclusion, BMED can be used for producing xylonic acid from fermentation broth. Moreover, this study highlights ways of improving the efficiency of BMED.


Assuntos
Diálise/métodos , Técnicas Eletroquímicas/métodos , Fermentação , Membranas Artificiais , Xilose/análogos & derivados , Meios de Cultura , Diálise/instrumentação , Técnicas Eletroquímicas/instrumentação , Tamanho da Partícula , Potássio/química , Sódio/química , Xilose/química , Xilose/isolamento & purificação
6.
J Pharm Biomed Anal ; 163: 58-63, 2019 Jan 30.
Artigo em Inglês | MEDLINE | ID: mdl-30286436

RESUMO

A fast, precise, and accurate method that can simultaneously determine 7 anions in whole blood was established by on line dialysis-double suppression ion chromatography. Performance parameters which could affect the determination of anions were optimized, including the selection of protein precipitant in samples, the amount of filtrate discarded, selection of eluent flow rate, influence of the Ag-Na column on experimental results, influence of ethylenediamines on ClO2-, and investigation of nitrogen drying. Finally, 3.6 mmol/L sodium carbonate was selected as eluent, with a flow rate of 0.8 mL/min, to separate the 7 anions. Blood and alcohol (v/v, 1:4) were used to precipitate the proteins in blood. The 7 anions reached an adequate recovery rate when the first 2 mL of filtrate from the C18 column was discarded. The recovery rate at LLOQ, low, medium, and high concentrations was 80-120%. The correlation coefficients (r2) of the calibration curves of the targeted anions ranged from 0.9975 to 0.9998. The limit of detection (LOD) was 0.309-7.71 µg/L. This method has simple pretreatment, high accuracy, and good reproducibility and selectivity, and is suitable for the separation and determination of anions in blood.


Assuntos
Ânions/sangue , Fracionamento Químico/métodos , Limite de Detecção , Ânions/química , Calibragem , Fracionamento Químico/instrumentação , Cromatografia por Troca Iônica/instrumentação , Cromatografia por Troca Iônica/métodos , Diálise/instrumentação , Diálise/métodos , Etanol/química , Humanos , Reprodutibilidade dos Testes , Solventes/química , Fatores de Tempo
7.
Rev Bras Enferm ; 71(4): 1915-1920, 2018.
Artigo em Inglês, Português | MEDLINE | ID: mdl-30156677

RESUMO

OBJECTIVE: to identify damages resulting from incidents with the Hickman® catheter. METHOD: descriptive, retrospective, qualitative approach. The source of data were the notifications of incidents that occurred between January 2012 and May 2015, as well as the information available on the medical records of patients involved in incidents with the Hickman® catheter. RESULTS: the incidents related to the Hickman® catheter with the greatest impact on patient care were obstruction, fracture and traction. All incidents caused damage to patients, in a greater or lesser degree, in the dimensions of physical damage and subjective damage. FINAL CONSIDERATIONS: damage or potential risk of damage was present in all incidents analyzed. The need to revise cleaning and obstruction protocols for the maintenance of the permeability of Hickman® catheters was demonstrated.


Assuntos
Infecções Relacionadas a Cateter/economia , Diálise/instrumentação , Transplante de Medula Óssea/efeitos adversos , Transplante de Medula Óssea/métodos , Análise Custo-Benefício , Diálise/métodos , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Pesquisa Qualitativa , Estudos Retrospectivos , Fatores de Risco
8.
Water Res ; 144: 296-303, 2018 11 01.
Artigo em Inglês | MEDLINE | ID: mdl-30053621

RESUMO

While flow-electrode capacitive deionization (FCDI) is a potential alternative to brackish and/or sea water desalination, there is limited understanding of both the fate of ions following migration across the ion exchange membranes and the mechanisms responsible for ion separation. In this study, we investigate the desalting performance of an FCDI system operated over a range of conditions. Results show that although ion transport as a result of electrodialysis is inevitable in FCDI (and is principally responsible for pH excursion in the flow electrode), the use of high carbon content ensures that a high proportion of the charge and counterions are retained in the electrical double layers of the flowing carbon particles, even at high charging voltages (e.g., 2.0 V) during the deionization process. Estimation of the portions of sodium and chloride ions adsorbed in the flow electrode after migration through the membranes suggests that the ongoing capacitive adsorption exhibits asymmetric behavior with the anodic particles demonstrating better affinity for Cl- (than the cathodic particles for Na+) during electrosorption. These findings provide an explanation for the change in electrode properties that are observed under imperfect adsorption scenarios and provide insight into aspects of the design and operation of flow electrode pairs that is critical to achieving effective desalination by FCDI.


Assuntos
Purificação da Água/instrumentação , Purificação da Água/métodos , Adsorção , Carbono/química , Cloretos/química , Diálise/instrumentação , Diálise/métodos , Eletrodos , Desenho de Equipamento , Troca Iônica , Sódio/química , Cloreto de Sódio
9.
Water Sci Technol ; 77(11-12): 2624-2634, 2018 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-29944127

RESUMO

Breweries release significant amounts of wastewater loaded with various organic and mineral materials. Prior studies of membrane bioreactor (MBR) wastewater treatment have been conducted with very little interest granted to the conditions of biomass acclimation. This study displays biomass behavior during brewery wastewater treatment by an aerobic MBR. In addition, nanofiltration and electrodialysis have been studied as potential post-treatment to decrease mineral concentrations and permit further water reuse for agriculture. An anoxic/aerobic laboratory MBR, associated with a flat sulfonated polyether membrane was used for synthetic brewery wastewater treatment. Biomass acclimation was performed using a feeding substrate. Organic concentrations in the MBR influent varied from 700 mg COD/L to 10,600 mg COD/L (COD: chemical oxygen demand) for 110 days. The results indicate a good acclimation to effluent with high salts and organic matter loads. Steady evolution of biomass concentration and activities was achieved after 90 days of operation. A reduction of COD of around 95% was obtained with MBR and up to 99% with nanofiltration post-treatment for the reconstructed brewery effluent with an organic loading rate of 7 g COD/L·d and a solid and hydraulic retention time of 30 days and 36 hours. A good reduction of the salt content was also recorded primarily with the nanofiltration and electrodialysis processes.


Assuntos
Reatores Biológicos/microbiologia , Diálise/instrumentação , Filtração/métodos , Indústria Alimentícia , Eliminação de Resíduos Líquidos/métodos , Adaptação Biológica , Aerobiose , Cerveja , Análise da Demanda Biológica de Oxigênio , Biomassa , Diálise/métodos , Filtração/instrumentação , Membranas Artificiais , Eliminação de Resíduos Líquidos/instrumentação , Águas Residuárias/química
12.
Nefrología (Madrid) ; 38(1): 34-40, ene.-feb. 2018. graf, tab
Artigo em Espanhol | IBECS | ID: ibc-170079

RESUMO

Introducción: Se ha asociado la hemodiafiltración on-line (HDF-OL) a un aumento de la supervivencia. Hasta el momento no está bien establecida la influencia del diámetro interno de las fibras capilares del dializador sobre la capacidad convectiva. El objetivo del estudio fue valorar el efecto del aumento del diámetro interno del dializador sobre el volumen convectivo y la capacidad depurativa. Material y métodos: Se incluyeron 16 pacientes en HDF-OL posdilucional con reposición automática. Cada paciente recibió 4 sesiones, en las que se varió el diámetro interno, 185μm (FX60 Cordiax y FX80 Cordiax) versus 210μm (FX600 Cordiax y FX800 Cordiax). En cada sesión se determinaron diferentes solutos al inicio y al final de la diálisis. Resultados: El incremento de diámetro interno entre FX60 vs. FX600 y FX80 vs. FX800 no reflejó diferencias en el volumen convectivo: 32,3±3,1 vs. 31,8±3,6 y 33,7±4,3 vs. 33,5±3,8L/sesión, respectivamente. Los porcentajes de reducción tampoco mostraron diferencias: urea 83,7±4,5 vs. 84,1±3,4 para FX60 y FX600 y 82,7±4,1 vs. 83,6±3,8 para FX80 vs. FX800; creatinina similar 78,2±5,6 vs. 77,8±4,6 y 77,1±5,4 vs. 78,1±4,9; β2-microglobulina 82,2±4,3 vs. 82,9±4,2 y 82,9±4,7 vs. 84,0±3,8; mioglobina 71,0±10, vs. 70,2±9 y 72,8±11 vs. 75,0±10; prolactina 70,4±9 vs. 68,1±9 y 72,2±10 vs. 73,4±8,2; y α1-microglobulina 22,9±10 vs. 21,6±10 y 26,5±12 vs. 28,8±11, respectivamente. Conclusión: El incremento del diámetro interno de las fibras capilares no ha significado una mayor eficacia en el volumen convectivo ni en la capacidad depurativa (AU)


Introduction: Online haemodiafiltration (OL-HDF) has been associated with increased survival. To date, the influence of the inner diameter of the hollow fibres of the dialyser on convective volume has not been well established. The objective of the study was to evaluate the effect of increasing the inner diameter of the dialyser on the convective volume and removal capacity. Material and methods: We included 16 patients in posdilutional OL-HDF with autosubstitution. Each patient was analysed in 4 sessions in which the inner diameter varied; 185μm (FX60 Cordiax and FX80 Cordiax) versus 210μm (FX600 Cordiax and FX800 Cordiax). Different solutes were measured at the beginning and end of each dialysis session. Results: No differences in the convective volume were found with an increased inner diameter: 32.3±3.1 vs. 31.8±3.6 l/session (FX60 vs. FX600) and 33.7±4.3 vs. 33.5±3.8 l/session (FX80 vs. FX800). The reduction percentages also did not differ: urea 83.7±4.5 vs. 84.1±3.4 for FX60 and FX600, and 82.7±4.1 vs. 83.6±3.8 for FX80 vs. FX800; creatinine similar 78.2±5.6 vs. 77.8±4.6 y 77.1±5.4 vs. 78.1±4.9; β2-microglobulin 82.2±4.3 vs. 82.9±4.2, and 82.9±4.7 vs. 84.0±3.8; myoglobin 71.0±10 vs. 70.2±9 and 72.8±11 vs. 75.0±10; prolactin 70.4±9 vs. 68.1±9, and 72.2±10 vs. 73.4±8.2; and α1-microglobulin 22.9±10 vs. 21.6±10, and 26.5±12 vs. 28.8±11, respectively. Conclusion: The increase in the inner diameter of the hollow fibres did not result in improved convective volume and removal capacity (AU)


Assuntos
Humanos , Masculino , Feminino , Adulto , Pessoa de Meia-Idade , Idoso , Idoso de 80 Anos ou mais , Diálise/instrumentação , Garantia da Qualidade dos Cuidados de Saúde , Hemodiafiltração/métodos , Hemodiafiltração , Heparina de Baixo Peso Molecular/uso terapêutico , Análise de Variância , Ultrafiltração/instrumentação , Ultrafiltração/métodos
13.
Water Sci Technol ; 76(9-10): 2733-2741, 2017 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-29168713

RESUMO

In this study, the effects of the combination of acid hydrolysis and Donnan dialysis on the high-quality struvite production from digested sewage sludge were examined. The Box-Behnken design was applied in the hydrolysis using oxalic acid for the optimization of the conditions that affect the nutrients and metal release from digested sludge. An optimal condition was obtained at oxalic acid 0.5 M, acid/sludge ratio (mL/g) 10/1, and reaction time 60 min. The separation of the metals from hydrolyzed sludge liquid was carried out with the Donnan dialysis using a Nafion 117 cation exchange membrane. At the end of the 4 hours of operating time, the recovery values for Zn, K, Na, Mg, Fe, and Al were obtained as 67.9%, 62.1%, 57.6%, 39.4%, 5.3%, and 2.5%, respectively. The produced struvite meets the legal limits for fertilizer use in terms of Cd, Cu, Ni, Pb, Zn, Hg, and Cr content specified by Turkish regulations. A high Ca/Mg molar ratio and the presence of K, Na, and Al affected the efficiency of struvite crystallization. The use of oxalic acid resulted in low Ca release, and the metal ions that affect struvite purity were eliminated using Donnan dialysis.


Assuntos
Diálise/métodos , Esgotos/química , Estruvita/isolamento & purificação , Ácidos/química , Diálise/instrumentação , Hidrólise , Estruvita/química
14.
Methods Mol Biol ; 1658: 23-26, 2017.
Artigo em Inglês | MEDLINE | ID: mdl-28861779

RESUMO

A key event in the pathogenesis of prion diseases is the change in structure of the normal cellular form of the prion protein from a predominantly α-helix form to the ß-sheet-rich prion protein found in disease-associated tissue. To allow more detailed structural research into PrP misfolding, it is necessary to have techniques which enable enrichment of the ß-sheet content in recombinant PrP.This method describes the procedure for inducing ß-folding of recombinant PrP to resemble a disease-associated structure and ultimately produce soluble ß-folded recombinant PrP.


Assuntos
Dicroísmo Circular/métodos , Soluções para Diálise/química , Diálise/métodos , Proteínas Priônicas/química , Dobramento de Proteína , Diálise/instrumentação , Humanos , Concentração de Íons de Hidrogênio , Conformação Proteica em alfa-Hélice , Conformação Proteica em Folha beta , Proteínas Recombinantes/química , Termodinâmica
15.
Water Res ; 125: 23-31, 2017 11 15.
Artigo em Inglês | MEDLINE | ID: mdl-28834766

RESUMO

When natural feed waters are used in the operation of a reverse electrodialysis (RED) stack, severe fouling on the ion exchange membranes and spacers occurs. Fouling of the RED stack has a strong influence on the gross power density output; which can decrease up to 50%. Moreover, an increase in the pressure loss occurs between the feed water inlet and outlet, increasing the pumping energy and thus decreasing the net power density that can be obtained. In this work, we extensively investigated the use of CO2 saturated water as two-phase flow cleaning for fouling mitigation in RED using natural feed waters. Experiments were performed in the REDstack research facility located at the Afsluitdijk (the Netherlands) using natural feed waters for a period of 60 days. Two different gas combinations were experimentally investigated, water/air sparging and water/CO2 (saturated) injection. Air is an inert gas mixture and induces air sparging in the stack. In the case of CO2, nucleation, i.e. the spontaneous formation of bubbles, occurs at the spacer filaments due to depressurization of CO2 saturated water, inducing cleaning. Results showed that stacks equipped with CO2 saturated water can produce an average net power density of 0.18 W/m2 under real fouling conditions with minimal pre-treatment and at a low outside temperature of only 8 °C, whereas the stacks equipped with air sparging could only produce an average net power density of 0.04 W/m2. Electrochemical impedance spectroscopy measurements showed that the stacks equipped with air sparging increased in stack resistance due to the presence of stagnant bubbles remaining in the stack after every air injection. Furthermore, the introduction of CO2 gas in the feed water introduces a pH decrease in the system (carbonated solution) adding an additional cleaning effect in the system, thus avoiding the use of environmentally unwanted cleaning chemicals.


Assuntos
Dióxido de Carbono , Diálise/métodos , Diálise/instrumentação , Impedância Elétrica , Eletricidade , Desenho de Equipamento , Concentração de Íons de Hidrogênio , Troca Iônica , Laboratórios , Membranas Artificiais , Microscopia Eletrônica de Varredura , Países Baixos , Centrais Elétricas
16.
Water Res ; 125: 123-131, 2017 11 15.
Artigo em Inglês | MEDLINE | ID: mdl-28843152

RESUMO

This paper describes the experimental campaign carried out with a reverse electrodialysis (RED) demonstration plant (Marsala, Italy) with the main aims of: (i) evaluating the effect of various operating parameters, including the redox processes, on the system performances; (ii) using the plant for the simultaneous generation of electric energy and treatment of wastewater. The prototype (44 × 44 cm2, 500 cell pairs) was tested using both real (brackish water and brine) and artificial solutions. Tests with two different electrode rinse solutions (with or without iron redox couples) were performed. In agreement with the data obtained in the laboratory, the presence of iron ions contributes positively to the power production. The effect of flow rates in the electrode and saline compartments, as well as aging of the electrode rinse solution was also investigated. The possibility to remove an organic pollutant (the azoic dye Acid Orange 7) from the electrode solution was tested, obtaining a very fast and total removal of the pollutant. This experimental campaign represents the first demonstration in a real environment of the abilities of a RED plant to treat wastewater, thus giving useful indications for the spreading of RED technology in the near future.


Assuntos
Diálise/métodos , Eliminação de Resíduos Líquidos/métodos , Diálise/instrumentação , Eletricidade , Eletrodos , Itália , Oxirredução , Eliminação de Resíduos Líquidos/instrumentação , Águas Residuárias
17.
Anal Chem ; 89(14): 7302-7306, 2017 07 18.
Artigo em Inglês | MEDLINE | ID: mdl-28648046

RESUMO

Equilibrium dialysis is a simple and effective technique used for investigating the binding of small molecules and ions to proteins. A three-dimensional (3D) printer was used to create a device capable of measuring binding constants between a protein and a small ion based on equilibrium dialysis. Specifically, the technology described here enables the user to customize an equilibrium dialysis device to fit their own experiments by choosing membranes of various material and molecular-weight cutoff values. The device has dimensions similar to that of a standard 96-well plate, thus being amenable to automated sample handlers and multichannel pipettes. The device consists of a printed base that hosts multiple windows containing a porous regenerated-cellulose membrane with a molecular-weight cutoff of ∼3500 Da. A key step in the fabrication process is a print-pause-print approach for integrating membranes directly into the windows subsequently inserted into the base. The integrated membranes display no leaking upon placement into the base. After characterizing the system's requirements for reaching equilibrium, the device was used to successfully measure an equilibrium dissociation constant for Zn2+ and human serum albumin (Kd = (5.62 ± 0.93) × 10-7 M) under physiological conditions that is statistically equal to the constants reported in the literature.


Assuntos
Diálise , Impressão , Albumina Sérica Humana/química , Zinco/química , Sítios de Ligação , Diálise/instrumentação , Humanos
18.
Biomed Microdevices ; 19(2): 30, 2017 06.
Artigo em Inglês | MEDLINE | ID: mdl-28421400

RESUMO

In this study, we present a multistage-dialysis microdevice (MDM) for extraction of cryoprotectants (CPAs) from a CPA-laden cell suspension. We confirmed the functions of the key designs of the MDM using a fluorescence solution, we assessed the performance of the MDM by using the MDM to unload glycerin from glycerin-loaded swine erythrocytes, and we investigated the effects of the cell suspension flow rate, glycerin concentration, cell density, and membrane pore size on the clearance efficiency of glycerin (CG), the survival rate of cells (SC), and the recovery rate of cells (RC). Under the designed conditions, CG, SC, and RC reached ~60%, ~90%, and ~70%, respectively. In addition, a high flow rate causes high SC and RC but a low CG. For a low glycerin concentration, CG, SC, and RC are all high. If a low cell density or a large pore membrane is used, CG is high, whereas both SC and RC are low. This work provides insight into the development of microfluidic devices for the inline extraction of cryoprotectants from a small volume of cryopreserved cells prior to the use of the cells in lab-on-a-chip applications.


Assuntos
Crioprotetores/isolamento & purificação , Diálise/instrumentação , Dispositivos Lab-On-A-Chip
19.
Biosens Bioelectron ; 94: 312-320, 2017 Aug 15.
Artigo em Inglês | MEDLINE | ID: mdl-28319897

RESUMO

A variety of electrical activities occur depending on the functional state in each section of the gut, but the application of microelectrode array (MEA) is rather limited. We thus developed a dialysis membranes-enforced technique to investigate diverse and complex spatio-temporal electrical activity in the gut. Muscle sheets isolated from the gastrointestinal (GI) tract of mice along with a piece of dialysis membrane were woven over and under the strings to fix them to the anchor rig, and mounted on an 8×8 MEA (inter-electrode distance=150µm). Small molecules (molecular weight <12,000) were exchanged through the membrane, maintaining a physiological environment. Low impedance MEA was used to measure electrical signals in a wide frequency range. We demonstrated the following examples: 1) pacemaker activity-like potentials accompanied by bursting spike-like potentials in the ileum; 2) electrotonic potentials reflecting local neurotransmission in the ileum; 3) myoelectric complex-like potentials consisting of slow and rapid oscillations accompanied by spike potentials in the colon. Despite their limited spatial resolution, these recordings detected transient electric activities that optical probes followed with difficulty. In Addition, propagation of pacemaker-like potential was visualized in the stomach and ileum. These results indicate that the dialysis membrane-enforced technique largely extends the application of MEA, probably due to stabilisation of the access resistance between each sensing electrode and a reference electrode and improvement of electric separation between sensing electrodes. We anticipate that this technique will be utilized to characterise spatio-temporal electrical activities in the gut in health and disease.


Assuntos
Técnicas Biossensoriais/instrumentação , Eletrofisiologia/instrumentação , Membranas Artificiais , Potenciais de Ação/fisiologia , Animais , Colo/fisiologia , Diálise/instrumentação , Íleo/fisiologia , Camundongos , Microeletrodos
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