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International audience; Introduction: The search for the 'perfect' renal replacement therapy has been paralleled by the search for the perfect biomarkers for assessing dialysis adequacy. Three main families of markers have been assessed: small molecules (prototype: urea); middle molecules (prototype β2-microglobulin); comprehensive and nutritional markers (prototype of the simplified assessment, albumin levels; composite indexes as malnutrition-inflammation score). After an era of standardization of dialysis treatment, personalized dialysis schedules are increasingly proposed, challenging the dogma of thrice-weekly hemodialysis.Areas covered: In this review, we describe the advantages and limitations of the approaches mentioned above, focusing on the open questions regarding personalized schedules and incremental hemodialysis.Expert opinion: In the era of personalized dialysis, the assessment of dialysis adequacy should be likewise personalized, due to the limits of 'one size fits all' approaches. We have tried to summarize some of the relevant issues regarding the determination of dialysis adequacy, attempting to adapt them to an elderly, highly comorbidity population, which would probably benefit from tailor-made dialysis prescriptions. While no single biomarker allows precisely tailoring the dialysis dose, we suggest using a combination of clinical and biological markers to prescribe dialysis according to comorbidity, life expectancy, residual kidney function, and small and medium-size molecule depuration.

The worldwide biomedical polymeric waste (BPW) production from dialysis treatment is estimated to be reached about 1.6 million tons/year by 2025, dramatically raising financial, environmental, and ...

PURPOSE This study explored the apparel wants and needs of people on dialysis using the user-centered design process. The study's aim was to understand the experiences and feeling of people on dialysis and their clothing barriers, along with exploring their functional needs and aesthetic wants in apparel items. METHODS To achieve the study's aim, 15 semi-structured qualitative interviews with people undergoing dialysis or caregivers were conducted in March 2017. In addition, researchers observed two dialysis clinics after hours for additional context. RESULTS Three theme categories emerged, which included (a) dialysis treatment, (b) challenges of dialysis, (c) dialysis clothing barriers. Within the framework of the user-centered design process, a deeper understanding of both the physical and emotional challenges of dialysis helped in finding barriers and giving design considerations for researchers, industry professionals, and educators. SIGNIFICANCE The findings help to give voice to a target market who desires to participant in consuming both fashionable and functional clothing. Current apparel for PLWD focus on the physical ailment and not the psychological well-being. The study's findings help to give recommendations to researchers, industry professionals, and educators when designing and developing apparel, products, and other environments for people on dialysis.IMPLICATIONS FOR REHABILITATIONPeople undergoing dialysis treatment are an under-served population in terms of clothing needs and wants, which results in both physical and emotional challenges.This study recommends researchers and industry professional to apply the user-centered design process when designing and developing apparel for people on dialysis.People on dialysis have a similar unappealing "uniform" that is worn during treatment that gives access to their site and blood pressure cuff, hides blood staining and allows for weight fluctuations.Apparel considerations for designing should consider to break down clothing barriers and improve mental health of people on dialysis.

Background COVID-19 has created havoc in healthcare systems worldwide, including shortages in equipment and supplies for dialysis in the acute setting. Methods We compared our planning and experience at a tertiary care academic medical center to recommendations in the literature. Results Published literature and our experience underscored the need to plan for adequate dialysis equipment, particularly for continuous renal replacement therapy in the ICU setting, adequate nursing, and flexible scheduling of chronic patients to accommodate the surge in acute patients. We discovered other "shortages" not mentioned in the literature: shortages in the number of portable reverse osmosis (RO) machines needed to prepare dialysis water, inadequate number of rooms in units designated for COVID-19 patients with plumbing for dialysis, and lack of temperature blending valves on sinks that necessitated using cold water only, and damaging the RO membranes. We identified the need for cooperation between nephrology and critical care medicine, hospital-based and community nephrologists and community dialysis units as well as nephrologists at other hospitals in the region. We turned to guidance from the hospital ethics committee. Conclusion Planning for an expected surge in hospitalized patients requiring RRT demands coordination between critical care, dialysis and nursing services as well as community and hospital providers to make certain there are adequate dialysis resources. Our experience suggests that continuous dialysis is in greatest demand early in the illness, and that plans to increase supplies should be put in place. But, planning should also focus on unforeseen hospital-specific infrastructure shortages that can develop over time and hamper intermittent dialysis delivery to all patients who require treatment.

In order to determine copper at trace level by flame atomic absorption spectrometry (FAAS), a supramolecular solvent-based liquid-phase microextraction method has been developed. 1-(2-pyridylazo)-2-naphthol (PAN) was used as a chelating agent to obtain the copper complex. In this method, supramolecular solvent was prepared by using tetrahydrofuran (THF) and decanoic acid. pH, THF volume, amount of decanoic acid, amounts of chelating agent, ultrasonic bath and centrifugation time, matrix effects and sample solution volume parameters which were effective on the recovery of the method were optimised. The detection limit (LOD) and quantification limit (LOQ) were 7.30 mu g/L, 24.2 mu g/L, respectively. The preconcentration factor was found to be 40. The accuracy of the method was determined by analysing TMDA 53.3 and TMDA 64.2 certified reference materials and some addition recovery tests. The presented method was applied to urine, sweat, dialysis solution and water samples to determine their copper level by flame atomic absorption spectrometry (FAAS).

Background: A silicon nanowire field effect transistor biosensor has four advantages in the detection of small biomolecules. It is mark-free, immediately responsive, highly sensitive, and specific. However, because of environments with a high salt concentration, the Debye screening effect has been a major issue in biological detection. Objective: To overcome Debye screening effect, realize the clinical application of silicon nanowire field effect transistor and verify its specificity and sensitivity. Materials and methods: The test solution was desalted by miniature blood dialyzer, and then the tumor markers were detected by silicon nanowire field effect transistor. Results: Tumor markers in serum were detected successfully and their sensitivity and specificity were verified. Conclusion: This method was found to effectively promote the development of semiconductor materials in biological solution detection.

Simplified engineering models are presented, characterizing Donnan dialysis separations of a single and multicomponent feed solutions by an overall transport coefficient combining mass transfer res...

This study was undertaken to develops a new sludge dewatering technology based on polyethylene glycol solution dialysis. This method significantly reduced the final water content of sludge when compared to conventional dewatering methods. It was found that when the osmotic pressure difference between the polyethylene glycol solution and the sludge reached 8 MPa, the moisture content in the sludge was reduced to 28.6%, facilitating deep dehydration. To further improve the dehydration effect and explore the technical feasibility of dialysis dehydration, a dehydration experiment was designed using the polyethylene glycol solution dialysis method combined with external pressure. By applying external pressure to the dialysis membranes, the particles in the sludge were compacted, which reduced the internal voids of the sludge and propelled continuous water discharge. The results demonstrated that the dehydration effect was significantly improved when compared to single dialysis. A scanning electron microscope (SEM) was used to observe and quantitatively analyze the microstructure of the sludge before and after dehydration and to compare the variations in sludge microstructure throughout the dehydration process. The relationships between the sludge moisture content and the porosity and pore equivalent diameter were obtained. This demonstrated the effectiveness of the dewatering experiment using sludge dialysis combined with external pressure. This study also investigates the dehydration mechanism of this method during the sludge dehydration process. This study provides a novel solution for sludge volume reduction that can be applied to sewage treatment in the future.

In this work semi-IPNs of cellulose acetate (CA) – N, N’- methylene bisacrylamide (MBA) – crosslinked polyacrylamide (PAM), and native CA gel were prepared and characterized by FTIR, AFM, SEM, XRD,...

Introduction: Liposomes are nanospheres of lipid bilayer which can bind drug either in the phospholipid membrane or in the central aqueous droplet. Liposomes loaded with a drug can facilitate drug ...

Using a two-compartment counter-current dialyzer with single passes, the simultaneous transport of hydrochloric acid and sodium chloride through an anion-exchange membrane Neosepta-AFN was studied at steady state. The diffusion dialysis process was quantified by four membrane mass transfer coefficients, which were correlated with the hydrochloric acid and sodium chloride concentrations in the feed. These characteristics were calculated from the experimental data on dialysis using a two-step procedure combining the numerical integration of the basic differential equations and a multivariable optimization. The second step of this procedure ensured the best agreement between the experimental and calculated data.

In this work, calcium alginate hydrogels have been prepared by a new technique, called ‘diffusion through dialysis tube’ (DTDT) which involved transfer of crosslinking ions into alginate solution via a dialysis tube with a molecular weight cutoff of 8 k Da. The various hydrogels, prepared with varying degree of crosslinking, were characterized by FTIR, XRD and TG analysis. We also investigated their dynamic water absorbency in phosphate buffer saline (PBS) of pH 7.4 and the data were interpreted in terms of various kinetic models. The equilibrium water uptake data was used to determine network parameters of hydrogels. Finally, the stability and water absorbency of these hydrogels were enhanced to a desired level by using crosslinker solutions, composed of Ba++/Ca ++and Zn++ / Ca++ ions.

We report polyvinyl alcohol (PVA)-based hybrid membranes composed of salt of lignin sulfonic acid (LSA) and tetraethyl orthosilicate. The concentration of LSA with respect to PVA varied from 10% to 40%. The hybrid membranes showed water uptake (WU) in the range of 122–210%, ion exchange capacities in the range of 0.32–0.75 mmol g−1, dialysis coefficient (UOH) from 0.0068 to 0.0119 m h−1, and selectivity (S) from 15 to 26. The hybrid membranes also showed thermal and mechanical stability.

Hemodialysis provides the life support system for patients suffering from end-stage renal syndrome (ESRD). This review presents the historical development of different polymeric materials used for the synthesis of dialysis membranes. Initially, cellulose acetate and its derivatives formed the bases of polymeric materials for dialysis membranes, followed by polyacrylonitrile, polysulfone and others. The biocompatibility issues of each of these polymers have been discussed along with the clearance of uremic toxins. The acceptability of a particular membrane material for dialysis is not based entirely on the issue of biocompatibility. The uremic toxin flux is an equally important factor when recommending a particular material for use as a dialysis membrane. An ideal dialysis material would yield a membrane with high flux of uremic toxins with minimum biological reactions. Along with the development of biomaterials, spinning technologies employed for spinning of dialysis grade membranes have also been illustr...

In this manuscript, the preparation of pyrrolidinium-based anion-exchange membranes (AEMs) from brominated poly(2,6-dimethyl-1,4-phenyleneoxide) (BPPO) is reported. Prepared membranes were completely characterized in terms of Fourier transform infrared spectroscopy (FTIR), thermogravimetric analysis (TGA), scanning electron microscopy (SEM), atomic force microscopy (AFM), ion-exchange capacity (IEC), water uptake (WR), linear expansion ratios (LER), mechanical stability, acid stability, etc. Excellent thermal, mechanical and acid stability can be observed for prepared membranes. Prepared membranes were used in diffusion dialysis (DD) process for acid recovery from model waste HCl/FeCl2 solution. The dialysis coefficient of HCl (UH) is found to be in the range of 0.018–0.049 m/h, whereas the separation factor (S) was obtained as 36.24–66.39. Prepared membranes show much better DD performance than that of commercial fibre–supported DF-120B membrane (0.004 m/h for UH, 24.3 for S at 25°C). Prepared me...

This work concerns the optimization of the neutralization dialysis process applied to water desalination. This process is used for salt removal from a NaCl model solution (initially 0.08 M) in a three-compartment membrane stack (acid, salt, and alkali compartments) with a cation-exchange membrane and an anion-exchange one, i.e. Neosepta® CMX and AMX, respectively. The desalination process has been investigated as a function of three main parameters, namely the initial concentration and the flow rate of acidic and alkaline solutions as well as the saline solution volume. A fractional factorial design, i.e. 25−1, has been employed to assess the parameters affecting the desalination efficiency, and specifically to study the ion-exchange of H+ and Na+ through CMX and that of OH− and Cl− through AMX. A linear theoretical model based on the experimental results has been carried out to account for the influence of the different parameters investigated and their relative interactions. The analysis of vari...

In this study, a two-stage diffusion dialysis (DD) and electrodialysis (ED) system for the removal and recovery of sodium hydroxide from industrial wastewater were investigated. The study was carried out at laboratory scale using food industry wastewater. Sodium hydroxide is commonly used as principal strong base by various chemical industries. The processed wastewater therefore enhances the pH levels of receiving water bodies that affects the physiological functions of aquatic organisms, plants, and makes the water inappropriate for human consumption. 1.0-μm PTFE (Advantec, USA), forward osmosis (FO) (Hydration Technology Innovation) membranes, platinum coated over titanium anode, and graphite cathode were used in this study. In the first stage of the DD process, NaOH from the feed solution (FS) i.e. wastewater to draw solution (DS) i.e. deionized water (DI) was carried out through PTFE membrane in a diffusion cell. The initial concentration of NaOH in the FS was from 1 to 3 M and in the first st...

A number of relevant issues are considered which show that it is essential to address the issue of in-centre meals during dialysis. This discussion paper critically explores the potential complications posed to patients who consume a large calorific intake during their dialysis treatment. The mission is to appeal to more dialysis units and outpatient departments to gradually implement a 'no food' policy during regular scheduled dialysis treatment sessions. The authors aim to put forward the significances and challenges and offer some possible solutions when introducing a 'no eating policy' like this into dialysis units. Nutritional supplements could, however, be offered on an as required basis.

Poly(sodium-p-styrene-sulfonate) (PSSS) is synthesized by the method of ARGET ATRP, then mixed with polyvinyl alcohol (PVA), and cross-linked with different alkoxysilanes, that is, tetraethoxysilane (TEOS), 3-aminopropyltriethoxysilane (APTS), or γ-glycidoxypropyltrimethoxysilane (GPTS). The obtained flexible cation-exchange membranes have water uptakes (WR) of 46.8–120.7% and ion-exchange capacities (IEC) of 1.03–1.64 mmol/g. The category of the alkoxysilanes strongly influences the membrane properties. The membrane from GPTS has the highest thermal stability with Td (temperature at 5% weight loss) of 267.4°C, the highest IEC, and the lowest swelling degree in 65°C water, which is due to the dual cross-linking of Si–O–Si and C–O–C between GPTS and PVA. When applied for diffusion dialysis (DD) process of NaOH/Na2WO4 mixture, the membranes exhibit excellent alkali flux. The OH− dialysis coefficients (UOH) are in the range of 0.0072–0.0208 m/h, higher than PVA blank membrane (0.0077 m/h) or commerci...

A simple approach for large-scale production of aqueous dispersions of fullerene C60 (nC60) with good stability was developed by mixing a solution of crystalline fullerene in N-methylpyrrolidone (NMP) with water followed by exhaustive dialysis against water. Addition of amino acids or sugars at low concentration before dialysis increases the stability of the dispersion. Measurement of the size and ξ-potential of particles in nC60 showed that their average diameter is 100 nm and charge about –30 mV. IR spectra of the dried dispersions showed the presence of a broadband characteristic for C‒O bond. Changing the solvent NMP to pyridine does not significantly affect the spectral characteristics of the resulting dispersion. Our data suggest that the fullerene molecule in nC60 is associated with MP and water molecules, and obviously is partially hydroxylated. The proposed method is promising for the preparation of aqueous solutions of endofullerenes.

The rate of mass transfer of three heavy metal ions such as Cu, Ni, and Zn across a regenerated cellulose membrane in a batch dialysis cell was measured by conductivity method by air-sparging. Air-spargingenhanced the rate of mass transfer depending on the air velocity. The increase in mass transfer coefficient ranged from 83.3 to 125%, 149.83 to 200%, and 99.4 to 201.52% for Cu, Ni, and Zn, respectively. The exponent values of superficial velocity agreed with the values obtained in previous studies on heat and mass transfer in bubble-stirred systems. The ranges of exponents were 0.0093

The existence of excess sodium dodecyl sulfate (SDS) molecules in a single-walled carbon nanotube (SWNT) solution dispersed by hybridization with SDS leads to unstable atomic force microscopy (AFM) imaging. In this study, we demonstrate sequential dialysis against pure water in order to remove excess SDS molecules from an SDS-SWNT hybrid dispersion. A 1:102 volume ratio of SDS-SWNT dispersion to water in the dialysis was found to be effective in realizing stable AFM observations of the SDS-SWNT hybrids despite imperfect filtering of SDS via dialysis. On the other hand, the SDS-SWNT hybrids were stable even when this volume ratio was 1:106. Further, the SDS-SWNT hybrids were present in the solution even when the dialyzed samples were stored for 14 days. Our results reveal that dialysis under optimal conditions enables improved handling of SDS-SWNT hybrids, particularly for stable AFM observations.

The membranes were prepared with various concentrations of polyamide and monosodium glutamate additive for dialysis application in this work. The membranes were characterized by determining creatinine diffusive permeability and by obtaining scanning electron microscope images and thermal characteristics. The results show that a membrane prepared without additive has a thick skin layer and a nonporous sublayer. The permeation of creatinine solute does not take place due to this dense (thick/nonporous) structure. When an additive is used in membrane synthesis, the thickness of skin layer reduces and voids are present, which results in permeation of this unwanted solute through the membrane.

Native alpha-lactalbumins (α-LA) from equine, bovine, and human milk were not cytotoxic. However, after treatment with trifluoroethanol (TFE), all three α-LAs exhibited cytotoxicity. Toxic potencies were distinctly different among them. Equine α-LA was the most robust, bovine α-LA was moderate, and human α-LA was weak. There were no significant structural changes as between the native and the TFE-treated α-LAs.

A process of chemo-dialysis involving poly(benzimidazole) (PBI) as a chemically active membrane material is proposed for the transport of inorganic acids. These membranes possessing basic nature selectively bind acid molecules present in the feed solution due to acid-base interactions. They are transported across the membrane by concentration gradient as the driving force. The transported acid molecules are stripped away from other side of the membrane surface by a suitable stripping agent or water. Effects of nature of feed acid (pKa, molecular size), its concentration in the feed solution and the nature of stripping agent (base or water) on acid transport properties are presented. Membranes showed appreciable transport rates for three acids, viz., H2SO4, HCl and HNO3. The fluxes for different acids varied from 16.1 to 140.7 g/m2 h under different operating conditions. Most significantly, there was no transport of non-acidic solutes such as NaCl or glucose. This could be made possible since thes...

Ozone is considered as a strongest oxidizer and disinfectant applied in drinking water treatment. If the water to be ozonated contains bromides, this will lead to the formation of bromates, ions with potential carcinogenic implications to human organisms. We proposed Donnan dialysis process with an anion-exchange membrane to remove bromate ions from water. The rate and efficiency of anion removal (BrO3 –, SO4 2–, HCO3 –) from the natural water were examined with the use of two types of anion-exchange membranes: Selemion AMV and Neosepta ACS and with the use of varying salt concentration in the receiver: 50, 100 or 200 mM NaCl. Bromate ions were removed from natural water with 90% efficiency in the process with the Neosepta ACS (of a highly cross-linked surface layer) when salt concentration in the receiver equalled 100 mM NaCl. The application of the Selemion AMV yielded similar efficiency of bromate removal (94%) but NaCl concentration in the receiver had to be twice as high as with Neosepta ACS (200 mM)...

The internal reflux effect on dialysis through the retentate phase of a cross-flow rectangular module is investigated. Theoretical analysis of mass transfer in cross-flow devices with or without recycling is analogous to heat transfer in cross-flow heat exchangers. In contrast to a device without reflux, considerable mass transfer is achievable if cross-flow dialyzers are operated with reflux, which provides an increase in fluid velocity, resulting in a reduction in mass-transfer resistance. It is concluded that reflux can enhance mass transfer, especially for large flow rate and feed-concentration operated under high reflux ratio.

A study on mass transfer in countercurrent cross-flow rectangular dialyzers with external recycle was investigated. Theoretical analysis of mass transfer in cross-flow dialyzers is analogous to heat transfer in cross-flow heat exchangers. In contrast to a single-pass cross-flow device without recycle, improvement in mass transfer of about 30% is achievable if a double-pass device of the same size with external recycle is employed, which provides the increase of fluid velocity, resulting in increase of mass-transfer coefficient. Higher effectiveness may be expected when dialysis is operated for the system in which the mass-transfer resistances in the liquid films are comparable with that in the membrane.

The first innovative model is developed in electro-dialysis reversal (EDR) desalination. First, theoretical limiting current density (LCD) determination is fitted and validated with four test-runs literature lab data. The goodness of fit and validation of LCD is statistically high with overall r 2 0.966 at p < 0.001. Second, a sensitivity analysis is done to study the most sensitive parameter in EDR with the LCD to its six modeling parameters; it was found that transport numbers of ions in membrane (t im) and in solution (t is) are rate limiting. Third, the model is constructed with emphases on LCD, concentration potential (CP), and total area of resistances of both membrane and solution to highlighting these two limiting parameters. Fourth, the model is fitted, verified, and validated with six different sets of both desalting energy and TDS in concentrate data from five literatures including 59 measured data points with five different feedwater characteristics. The values of five parameters (t Ca++, m′, ...

The overall dialysis coefficient, which is the basic transport characteristic of a dialysis process, can easily be determined from experimental data obtained in a two-compartment dialysis cell. Here, the volume changes and the concentrations of component in both the compartments are recorded as functions of time. Generally, all these input quantities can be loaded with an experimental error. The paper deals with the transformation of concentration and liquid volume errors into the final results under the conditions of constant liquid volumes in both the compartments of the dialyzer. Using the generated precise experimental data, small random errors have been introduced into them and the effect of these errors upon the overall dialysis coefficient has been evaluated. The error analysis has proved that the unfavourable effect of the input quantities is dependent upon intensity of mass transfer. Moreover, in some cases the effect of the input quantities can be eliminated to some extent using reconciled exper...

The liposome immobilized on indium tin-oxide electrode was prepared as a “Membrane Chip” to evaluate the liposome-liposome interaction. Three kinds of neutral liposomes entrapping the fluorescence probe, calcein, were utilized as a sensory liposome. Twenty four kinds of liposomes were used to construct a membrane library based on the calcein release behavior. The loading of liposome including the unsaturated phospholipid into the dialyzer induced the variation of surface state of liposome membrane. We analyzed the above liposome by a comparison of it with the membrane library constructed by Membrane Chip. The liposome after its dialysis treatment was found to show the membrane property of the liposome with domain-like structure prior to the interaction with amyloid β protein. Also the above liposome showed the oxidized liposome-like membrane property. In conclusion, we demonstrated a membrane library-based method to evaluate the surface state of the model biomembranes with unclear surface property.

The effect of external recycle on the performance of dialysis in cross-flow rectangular membrane modules with feed-stream recycle was investigated theoretically. The analysis of mass transfer in parallel-plate devices with and without recycle is analogous to heat transfer in parallel-plate heat exchangers. In contrast to a device without recycle, improvement in mass transfer is achievable if cross-flow parallel-plate dialysis is operated in a device of the same size with recycle, which provides increased fluid velocity, resulting in reduction of the mass-transfer resistance.

The mechanism of the diffusive boron transfer through anion exchange AMX (Neosepta) membrane was evaluated by multiple regression methods. It was found that Donnan dialysis (OH-B(OH)4 - exchange) phenomena dominates over simple boric acid diffusion dialysis. Thus to enhance boron fluxes as well as its removal efficiency the process should be carried at as high as possible receiving solution pH while the feed solution pH should be maintained low.

The aim of this study was to determine the efficacy and feasibility of estimating dialysis adequacy using ionic dialysance (ID). We retrospectively reviewed the medical records of patients receiving thrice weekly dialysis for an eight-month period at a single-center Veterans Affairs hospital. Dialysis adequacy was determined monthly using pre- and post-treatment BUN measurements to calculate the single pool Kt/V (spKt/V) with the formula set forth by Daugirdas. On the same treatment day, K(ID)t was determined by multiplying the average ID times the time (t) of the treatment. A surrogate volume, V(ID), was estimated by dividing K(ID)t by spKt/V using data from the first six months. During the subsequent two months, we compared dialysis adequacy estimated by urea-based spKt/V to ionic dialysance based K(ID)t/V(ID) utilizing V(ID). In the first month, K(ID)t/V(ID) estimations and the simultaneous spKt/V determinations averaged 1.55 +/- 0.36 and 1.59 +/- 0.42, respectively. In the second month, K(ID)t/V(ID) and spKt/V averaged 1.52 +/- 0.33 and 1.54 +/- 0.35, respectively. K(ID)t/V(ID) correlated well with spKt/V, as the slope was 0.85 (r = 0.95, p0.001). There was considerable intra-patient variability of K(ID), time, and K(ID)t/V(ID) with coefficient of variations (CV) of 8.4 +/- 4.3, 9.0 +/- 5.3, and 15.8 +/- 9.2, respectively. However, the CV for K(ID)t/V(ID) was similar to the CV for spKt/V (15.3 +/- 7.4). These results suggest that it is possible to estimate dialysis adequacy during every treatment using K(ID)t/V(ID). Furthermore, there is considerable variability in the delivered dialysis adequacy, suggesting that many sessions result in sub-optimal dialysis.

The article is devoted to the theoretical aspects of the development of the effective method for the removal of protein-bound uremic toxins. It is shown that the methods of flow and differential scanning microcalorimetry are sufficient enough for the evaluation of the degree of ligand loading of human serum albumin with protein-bound uremic toxins. The molecules of albumin isolated from blood plasma of the patients being kept on chronic dialysis are demonstrating significant alterations of conformation and complex-forming properties, the correction of which by conventional methods of extracorporeal detoxification (exhaustive dialysis, treatment on synthetic SCN carbons) are practically ineffective. Deliganding of uremic albumin may be successfully performed on conventional carbon haemosorbents upon preliminary separation of blood plasma and its dilution with acetate buffer 1:1 at pH = 5.08. Treatment of the whole blood of patients onto new mass-fractal deliganding carbon, i.e., hemosorbents of HSGD trademark. These HSGD haemosorbents quite effectively could be used for restoration of main parameters of uremic HAS molecules conformation and ligand-binding activity simultaneously with hemodialysis upon the protection by locally performed citrate anticoagulation as an easier and cheaper method for the removal of protein-bound uremic toxins.

The method uses preparative centrifugal precipitation chromatography comprising a seal‐free continuous‐flow centrifuge machine equipped with a plastic disk and a spiral groove which accommodates convoluted tubing. A dialysis membrane is inserted into the convoluted tubing to separate proteins according to their solubility in ammonium sulfate solution. The system relies on the original model of centrifugal precipitation chromatography, which employs the centrifugal force and a concentration gradient of precipitants to perform a repetitive process of precipitation and dissolution of protein molecules. Compared to the previous model, the current model results in a higher yield of separated compounds.

An investigation in three replications was conducted to study the release and diffusion of iron (Fe) from iron-humate (Fe-HA) chelates and to assess its availability to growing plants. Labeled, 59Fe-HA, chelates, contained in dialysis bags, were dialyzed against distilled water, a Hoagland nutrient solution, a solution of 10−4 ethylenediamine tetraacetic acid (EDTA) or diethylenetriamine pentaacetic acid (DTPA), and 10−4 M citric acid, and the amount of radiation in the respective solutions measured at 1, 4, and 14 days after dialysis. Assessment of plant uptake of chelated 59Fe-HA and transport of Fe from root to leaf-tissue were examined by growing plant seedlings in Hoagland solutions for 30 days. The Fe source was labeled 59Fe-HA chelates, contained in dialysis bags, placed in the nutrient solutions, treated with or without EDTA. Since different plants were believed to exhibit different mechanisms, called strategies, in absorption and transport of Fe, two types of plants were grown, sunflower...

Microorganisms associated with basalt core were compared to those suspended in groundwater pumped from the same well in the eastern Snake River Plain Aquifer (Idaho, USA). Two wells located at different distances from the source of a mixed-waste plume in the fractured basalt aquifer were examined. In the well more distal from the plume source, an array of dialysis chambers filled with either deionized water or crushed basalt was equilibrated to compare the microorganisms collected in this fashion with those from core and groundwater samples collected in a traditional manner from the same well. The samples were characterized to determine the total amount of biomass, presence of specific populations or physiological groups, and potential community functions. Microorganisms and their activities were nearly undetectable in core and groundwater collected from the well farthest from the plume source and substantially enriched in both core and groundwater from the well closest to the plume source. In both wells,...

The pioneering work of Yatzidis[[1]] and Chang[[2]] who utilized conventional carbon for augmentation of dialysis efficiency, focused the world's attention for their potential use in uremia. As sor...

An on-line dialysis preconcentration determination of nitrite by injection method has been developed. In this paper, the polyetherimide-composed membranes (PEI) were used for the dialysing of the nitrite from the food samples matrix, because they showed a high dialysing yield and analytical signal, low blank signal and absence of membrane clogging. In the recipient (acceptor) stream, the nitrite which penetrated from the PEI membrane, is diazotised with sulphanilamide to form a diazonium action, which is supsequently coupled with N-(1-naphthyl)-ethylenediamine dihydrochloride to form a stable purple azo dye, the absorbance of which is measured at 525 nm. Various analytical parameters, such as effect of acidity (pH), flow rate, sample size, dialysing membranes, and interfering species were studied. The calibration curve was between 12.5 ng ml-1 and 3.2 µg ml-1, and the detection limit was 4.5 ng ml-1, and up to 15 samples can be analyzed per hour with a relative precision of ca.2.8%. The proposed method wa...

Development of a simple, rapid, and accurate methodology for clenbuterol residue extraction in bovine hair and retina by diphasic dialysis was evaluated. After bovine hair and retina samples digestion, diphasic dyalisis was used as an extraction procedure using four organic solvents (dichloromethane, n-hexane, ethyl acetate, and diethyl ether) and five different buffers (acetate, phosphate, borate, carbonate, and citrate). The organic extract was evaporated to dryness under a nitrogen stream and the residue was derivatized with butylboronic acid. The results of GC-MS determination show that acetate buffer [sodium acetate 0.2M: acetic acid (95:5) pH ≈ 5.8] was the best choice for buffer dialysis, when dichloromethane and diethyl ether were elected as extraction organic diphasic dialysis solvents for hair and retina, respectively. Discussion of validation data show that diphasic dialysis could be a good, rapid, accurate, and economic extraction procedure to determine clenbuterol in bovine hair and retina sa...

Refolding of CAB was studied at high concentrations of protein and urea. Aggregate formation was decreased by using higher concentrations of urea in refolding buffer. Refolding yields of 60% were obtained at high concentrations of CAB by using urea concentrations of 3.0-4.0 M in renaturation mixture. Comparison of the refolding yield and the amount of soluble CAB in renaturation mixture indicated that the apparent specific activity of refolded CAB was lower than that of native one at higher concentrations of urea. Difference in the steric structures of native and refolded CAB was observed in CD spectra of these samples. However, removal of urea from loosely folded CAB solution by dialysis recovered the native structure of CAB, as well as its native specific activity. Hence the refolding efficiency after dialysis was improved to about 70-80% at CAB concentrations of 3-5 kg/m3. Effect of incubation time of renaturation mixture before dialysis was studied, and it was shown that incubation time less than 3 hours increased aggregate formation and decreased the refolding yield. Therefore, formation of more stable intermediates in the refolding pathway decreases aggregate formation during urea removal. These results lead to a consecutive dilution-dialysis method for refolding at high concentrations of proteins.

Noncrystalline silica was obtained with lows iron, sodium, and nitrate ions concentrations from soluble sodium silicate (water glass) and nitric acid solution. Extractions with nitric acid solution...

Immunoaffinity chromatography can be applied to the treatment of biological samples. It consists of the separation, extraction, or purification of a molecule (para nitro analine in this paper) from a mixture by a selective interaction with an antibody. The latter is produced by living organisms after their contact with an antigen (modified protein in this case). The production of specific antibodies highly depends on the purity of antigen. This paper describes and compares two methods of antigen purification: dialysis and gel permeation chromatography. This chromatographic method allows one to obtain a pure antigen faster than dialysis but with a slightly larger dilution of the samples. It is not a drawback for the procedure of the antibodies production.

Harbor seal blubber samples were analyzed for PCDD/Fs and PCBs by splitting the initial extract into three aliquots and applying three different techniques for lipid removal (the first step of sample cleanup methodology for GC-HRMS analysis): gel permeation chromatography (GPC), sulfuric acid treatment, and dialysis through semipermeable membrane. Correlation coefficients of analyte concentrations obtained from three sets of replicate samples ranged from 0.965 to 0.994. In addition, a number of seal blubber samples were processed without pre-extraction using only the dialysis technique. The analyte concentrations in these samples correlated well with the analyte concentrations obtained from dialyzed blubber extracts (correlation higher than 0.998). For all analyses (PCDD/Fs, NO- and MO-PCBs) the average surrogate standard recoveries for the GPC and dialysis techniques varied from 68 to 111%. The recoveries for PCDD/Fs and MO-PCBs standards ranged from 61 to 89% and 36 to 43% for the NO-PCBs when ...

Inhibition of rat brain glutamate decarboxylase (GAD, EC 4.1.1.15) by individual stereoiso-mers of 4-fluoroglutamate (4-F-Glu) and 2-fluoro-4-aminobutyrate (2-F-GABA) was studied. All stereoisomers of 4-F-Glu inhibited decarboxylation of L-glutamate catalysed by the enzyme preparation. At 1 × 10−2 M concentration, the most potent inhibitor of GAD was D-erythro-4-F-Glu with about 70% inhibition in the presence of 1.23 × 10−2 M L-glutamate. The inhibition by all stereoisomers was of the competitive type. Ki values ranged from 2 × 10−3 M for the D-erythro isomer to 1.1 × 10−2M for the D-threo and L-erythro isomers. The influence of all stereoisomers was reversible as shown by dialysis except for a small amount in the case of the D-erythro isomer. The inhibition was independent of external pyridoxal-5′-phosphate added. No inhibition of rat brain GAD was found with 2-fluoro-4-aminobutyrate stereoisomers.

This study deals with the effect of an exponential-decay flux of ultrafiltration on the mass transfer rate of solute for dialysis in cross-flow membrane modules. The numerical method of orthogonal collocation was used to solve this problem. The calculated results of solute concentrations and separation efficiencies were analyzed under various operating conditions and decay coefficients of flux in ultrafiltration. The mass transfer rate is usually enhanced by the addition of the effect of ultrafiltration, but this effect decreases as the decay coefficient increases. A significant influence of the decay coefficient on the mass transfer rate appears when the solute transport is dominated by the effect of ultrafiltration, i.e. the conditions of lower dialysate flow rate, lower solute sieving coefficient, or lower overall mass transfer coefficient.

The aim of this study was to assess the suitability of automated dialysis, using a commercial system, for the analysis of sulphonamides in porcine tissue. The system involves automated dialysis, followed by trace enrichment of the dialysate prior to HPLC determination. The procedure was applied to the analysis of nine sulphonamide drug residues using reversed phase HPLC as the method of determination. Muscle samples were blended in saline, centrifuged and the supernatant was filtered before dialysis for an optimised time of 11 min. The resulting dialysate was concentrated on a reversed phase trace enrichment cartridge prior to HPLC analysis with UV detection at 280 nm. The developed method was evaluated by carrying out intra- and inter-assays on fortified porcine muscle. Mean recoveries, evaluated from the inter-assay study, were 80% or higher for the nine sulphonamides studied and the limit of determination for the method was 40 ng g−1.

Sir,Insulin resistance increases circulating malondialdehyde-modified LDL and impairs endothelial function in healthy young men.[1] In diabetics, oxidative stress impairs glucose uptake in muscle a...