Solute Retention Research Articles

Ultrathin membranes comprising polymers of intrinsic microporosity oligomers for high-performance organic solvent nanofiltration

Microporous organic polymers (MOPs) featuring chemically rigid backbones and permanent micropores are desirable for fabricating molecular selective membranes towards organics separation. However, coordinating facile film processing with high micropore persistence remains a challenge. In this paper, a low molecular weight polymers of intrinsic microporosity was rationally designed by precisely controlling the stoichiometric equilibrium of polymerization monomer. The polymers of intrinsic microporosity oligomers combine rigid and contorted structures with the aqueous solution processability, promoting the formation of 25-nm-thick polyacrylamide nanofilms with enhanced microporosity via support-free interfacial polymerization (SFIP). The resulting composite membranes have superior retention of small molecular solutes and high nonpolar and polar solvent permeances. Experiment and simulation results show that their excellent separation performance is due to substantially open and interconnected microporosity formed in the polymer networks based on rigid and contorted diamines as well as reduced film thickness. This study provides a new sight for using MOPs to construct high-microporosity membranes for precise and rapid molecular sieving.

Screening of the biphenyl polyamides nanofilms appropriate for molecular separation in organic solution feed

Developing polymeric separation membranes that combine excellent solvent stability, high permeability, and customizable molecular weight interception remains a challenge. Herein, thin-film composite (TFC) polyamide (PA) membranes with poly(ether ether ketone) (PEEK) support and biphenyl-centered polyamides active layer were fabricated through interfacial polymerization technique for the first time. Enhanced solvent stability was exhibited by the fabricated membranes due to the intrinsic resistance to organic solvents possessed by PEEK and biphenyl polyamides. The separation performance of the obtained membranes was systematically studied by relating to the properties of PA nanofilms in terms of nano-mechanical strength, morphologies, and microporosity. The organic solvent nanofiltration (OSN) performance of the resultant membranes in terms of permeability and molecular weight cut-off (MWCO) could be regulated. The optimized membrane exhibited a pure solvent permeability as high as 21.6 L m−2 h−1 bar−1 for acetonitrile and 14.0 L m−2 h−1 bar−1 for methanol. It also showed excellent long-term durability with almost unchanged permeability as well as solute retention remained above 97.8 % after a cumulative OSN operation of N, N-Dimethylformamide (DMF) based feed for 240 h. In particular, OSN membrane with targeted MWCOs covering the range of 170–370 g·mol−1 could be fabricated by selecting appropriate biphenyl acyl chlorides as building blocks. This approach offers a scalable and versatile platform for the development of solvent-stable, highly permeable, and customizable MWCO membranes for process-oriented OSN.

Energy and exergy analysis of a novel solar-powered passive multi-stage osmosis desalination system for sustainable water production

Climate change and population growth constantly exacerbate global water scarcity, and seawater desalination technology is crucial to addressing this crisis. Conventional fossil-fuel desalination poses environmental and economic challenges, especially in remote, water-scarce regions. Renewable energy offers sustainable options for seawater desalination; however, most related technologies face challenges in flexible deployment. Among passive technologies, interfacial evaporation still confronts issues of salt accumulation impacting desalination efficiency. Therefore, this study investigates a novel solar-powered passive multi-stage osmosis device that emulates mangroves’ transpiration and natural osmosis processes. Harnessing solar energy, it employs hydrophilic nanoporous membranes for water movement and evaporation and an osmosis membrane for solute retention, aiming for efficient seawater desalination without external power and pressure. Energy and exergy analyses reveal key efficiency factors. Results reveal significant pressure gradients across the osmosis membrane as a challenge. Optimizing salinity and adjusting the area ratio of the nanoporous membrane to the osmosis membrane is vital for stability and performance. Moreover, potential increases in water production from 0.97 kg/m2/h to 3.53 kg/m2/h with a five-stage setup, though benefits diminish with additional stages due to heat/exergy losses. The exergy efficiency increases from 0.14 % for a five-stage device to 0.18 % for a ten-stage system. This study demonstrates the solar-powered passive multi-stage osmosis device’s dependence on solar flux and highlights the importance of optimizing the air gap thickness and insulation to boost efficiency.

Retention factor variation on wide range of mobile phase compositions in reversed-phase high-performance liquid chromatography; a short tutorial

Mobile phase composition remains the major experimental parameter influencing the separation process in reversed-phase high-performance liquid chromatography (RP-HPLC). Its influence on the retention of solutes is explained by the Hildebrand solubility parameter and solvophobic theory, which also considers molecular characteristics of the participants in a separation process. The main empirical dependences (linear and polynomial) between the retention factor and the composition of mobile phase (retention function) are discussed taking into consideration a wide range of mobile phase compositions. Two direct chromatographic indices are resulting from these equations: the extrapolated value of retention factor for zero organic content in mobile phase composition (log kw) and the solvent strength parameter (S), which for a linear retention function is its slope being constant over the entire mobile phase compositions. Another chromatographic index could result from the retention function for zero content of water in mobile phase, but this situation can be applied only for very hydrophobic solutes. For large domains of mobile phase composition, the retention function cannot be described by a single type of dependence. This explains the paradox of generating by extrapolation different logkwvalues for different organic components. For the mobile phase close to pure water the retention function is different from that at average water concentration.

Exploring the potential of 5G uplink communication: Synergistic integration of joint power control, user grouping, and multi-learning Grey Wolf Optimizer

Non-orthogonal Multiple Access (NOMA) techniques offer potential enhancements in spectral efficiency for 5G and 6G wireless networks, facilitating broader network access. Central to realizing optimal system performance are factors like joint power control, user grouping, and decoding order. This study investigates power control and user grouping to optimize spectral efficiency in NOMA uplink systems, aiming to reduce computational difficulty. While previous research on this integrated optimization has identified several near-optimal solutions, they often come with considerable system and computational overheads. To address this, this study employed an improved Grey Wolf Optimizer (GWO), a nature-inspired metaheuristic optimization method. Although GWO is effective, it can sometimes converge prematurely and might lack diversity. To enhance its performance, this study introduces a new version of GWO, integrating Competitive Learning, Q-learning, and Greedy Selection. Competitive learning adopts agent competition, balancing exploration and exploitation and preserving diversity. Q-learning guides the search based on past experiences, enhancing adaptability and preventing redundant exploration of sub-optimal regions. Greedy selection ensures the retention of the best solutions after each iteration. The synergistic integration of these three components substantially enhances the performance of the standard GWO. This algorithm was used to manage power and user-grouping in NOMA systems, aiming to strengthen system performance while restricting computational demands. The effectiveness of the proposed algorithm was validated through numerical evaluations. Simulated outcomes revealed that when applied to the joint challenge in NOMA uplink systems, it surpasses the spectral efficiency of conventional orthogonal multiple access. Moreover, the proposed approach demonstrated superior performance compared to the standard GWO and other state-of-the-art algorithms, achieving reduced system complexity under identical constraints.

Cation-modulated permselectivity regulation of polyelectrolyte nanofiltration membranes for water purification

Polyelectrolyte multilayer (PEM) membranes fabricated by layer-by-layer (LBL) assembly have been widely adopted for nanofiltration (NF) due to their unique merits of highly tunable surface charge and pore size. However, current PEM membranes generally suffer from cumbersome preparation procedures and unsatisfying water permeance and/or solute retention rates, which stymie their practical applications. This study discloses a facile and effective method to deliberately regulate the interactions between polyelectrolytes and their LBL assembly behaviors by using cations with various valences and sizes as the modulators. Compared with the acquiescent background electrolyte NaCl, the PEMs modulated by divalent cations (i.e., Ca2+) exhibit intensified surface electronegativity with dense packing structures, and the resulting PEM membranes thus show high rejections for both inorganic salts (i.e., 94.0 % for Na2SO4) and negatively charged emerging micropollutants (EMPs) (i.e., 94.9 % and 99.9 % for tetracycline hydrochloride and perfluorododecanoic acid, respectively). In contrast, monovalent cations (i.e., Li+) lead to the formation of PEMs with loose structures and strong surface electronegativity, which endow the PEM membranes with a high water permeance of 15.0 LMH/bar and slightly reduced solute rejections. Nevertheless, the retention rates of Na2SO4 and perfluorooctanoic acid still surpass those obtained by the NaCl-modulated PEM membrane. Interestingly, trivalent cations such as Fe3+ and Al3+ are unable to facilitate the formation of an intact PEM. Characterization data and theoretical models imply that cations play a pivotal role in the stacking structure of PEMs through synergistically modulating polyelectrolyte-counterion interactions and the overcompensation and subsequent site diffusion of polyanions. This work demonstrates an effective approach to finely tune the nanostructure and permselectivity of the PEMs, which provides a valuable platform for the rational design of PEM NF membranes for effective separations of salts and EMPs.

Evaluation and Management of Kidney Dysfunction in Advanced Heart Failure: A Scientific Statement From the American Heart Association.

Early identification of kidney dysfunction in patients with advanced heart failure is crucial for timely interventions. In addition to elevations in serum creatinine, kidney dysfunction encompasses inadequate maintenance of sodium and volume homeostasis, retention of uremic solutes, and disrupted endocrine functions. Hemodynamic derangements and maladaptive neurohormonal upregulations contribute to fluctuations in kidney indices and electrolytes that may recover with guideline-directed medical therapy. Quantifying the extent of underlying irreversible intrinsic kidney disease is crucial in predicting whether optimization of congestion and guideline-directed medical therapy can stabilize kidney function. This scientific statement focuses on clinical management of patients experiencing kidney dysfunction through the trajectory of advanced heart failure, with specific focus on (1) the conceptual framework for appropriate evaluation of kidney dysfunction within the context of clinical trajectories in advanced heart failure, including in the consideration of advanced heart failure therapies; (2) preoperative, perioperative, and postoperative approaches to evaluation and management of kidney disease for advanced surgical therapies (durable left ventricular assist device/heart transplantation) and kidney replacement therapies; and (3) the key concepts in palliative care and decision-making processes unique to individuals with concomitant advanced heart failure and kidney disease.

Washing machine filters to mitigate microplastics release: Citizen science study to estimate microfibers capture potential and assess their social acceptability

The accumulation of microplastics in the environment, particularly due to the significant contribution of synthetic clothing washing water, leads to a need for developing source-based retention solutions. The project's objective is to assess the capability of washing machine filters to capture microfibers from domestic wastewater under real laundry conditions. This involves developing a protocol for quantifying microfibers tailored to washing machine lint samples, estimating the potential microfiber capture by washing machine filters, and evaluating the social acceptability of using such filters in households. Volunteers were recruited and they used their washing machines normally, collecting lint in the filter over a 6-month period and documenting information for each load. Various reagents were tested using plastic controls and lint samples to select the most efficient one for removing organic matter without affecting microplastics. Microscopic visual alterations, chemical signatures via FTIR, and the efficacy of the digestion protocol were assessed through mass balance and visual counting. After discarding digestion protocols affecting plastic integrity, those ensuring the most efficient mass loss of organic matter were identified as H2O2 30 % for 5 days at room temperature (RT), NaOCl 3 % for 24 h at RT, and H2O2 30 % at 40 °C for 24 h. Polyester, acrylic, and polyamide controls were tested with NaOCl 3 % for 24 h and H2O2 30 % for 5 days, showing no changes in SEM images. The FTIR successfully recognized the chemical signature. More significant alterations on positive samples (cotton and cellulose) were observed after NaOCl exposure. The mean mass of microfibers remaining after digestion was estimated at 4.62 mg per liter of washing water or 61 mg/kg of washed garment. The survey revealed that 67.8 % of volunteer participants found the filter installation challenging, and 21.4 % had to hire a plumber, highlighting potential challenges associated with implementing washing machine filters on a large scale.

African Women in Neurosurgery: An Exploration of Historical Perspectives, Current Realities, and Future Prospects

Gender disparities remain a significant issue, particularly impacting African women in the field of neurosurgery. Databases, articles, and perspectives were reviewed to identify challenges faced by African Women in Neurosurgery (AWIN), and explore solutions for recruitment, retention, and career advancement of AWIN. In 1982, Africa saw its first female neurosurgeon, with the first female president of the World Federation of Neurosurgical Societies appointed 4 null decades later. Presently, the continent hosts 245 female neurosurgeons, with North Africa comprising the majority at 76.3%, with Algeria notably contributing 72.2% of this total. Southern Africa contributes 7.8%, while West Africa, East Africa, and Central Africa contribute 6.5%, 6.1%, and 3.3%, respectively. Thirteen countries lack neurosurgeons entirely and 30 out of the 54 African nations face shortages of female neurosurgeons, with distributions as follows: North Africa (1-country), Southern Africa (6-countries), West Africa (8-countries), East Africa (9-countries), and Central Africa (6-countries). Our analysis mapped the distribution of 245 AWIN across the African regions and examined the professional trajectories and achievements of 17 pioneering AWIN. Additionally, we compiled registries for: 1) 76 neurosurgical training programs across 26 African countries, 2) organizations tackling gender disparities in neurosurgery, and 3) recommendations to promote AWIN across governmental, community, and academic spheres. To boost AWIN representation in neurosurgery, concerted and comprehensive efforts are vital. Collaboration among medical schools, training programs, and governments is key to fostering diversity and inclusivity in African neurosurgical settings.

The role of the cation and anion in aqueous liquid chromatography with sodium dodecyl sulphate and imidazolium-based ionic liquids as mobile phase reagents

BackgroundIn reversed-phase liquid chromatography, solute retention is primarily influenced by interactions between a nonpolar stationary phase and a moderately polar hydro-organic mobile phase, based on the solute lipophilicity. However, challenges regarding retention and peak tailing can arise due to ionic interactions between positively charged analytes and free silanols present on silica-based stationary phases. To address these challenges, incorporating surfactants and ionic liquids (ILs) into the mobile phase offers an effective solution. These additives synergistically enhance chromatographic performance through electrostatic and lipophilic interactions, which enable fine-tuning of selectivity and improved separation efficiency. ResultsThis study explores the chromatographic behaviour of several basic compounds in aqueous mixtures containing the anionic surfactant sodium dodecyl sulphate (SDS), above its critical micellar concentration, combined with various 1-alkyl-3-methylimidazolium-based ionic liquids (ILs) featuring chloride, tetrafluoroborate, and hexafluorophosphate anions, all without the addition of organic solvents. Specifically, this research investigates the influence of different anion types within the ILs and considers the impact of the IL cations. Analysis of solute peak profiles reveals narrow and symmetrical peaks. By introducing tetrafluoroborate and hexafluorophosphate IL anions into a mobile phase that contains an anionic surfactant, the study sheds light on the interactions occurring within the chromatographic column. This enhanced understanding of the combined effects of surfactants and ILs contributes to refining chromatographic methodologies. SignificanceThis research highlights the importance of carefully selecting the appropriate IL when incorporating it into a micellar mobile phase alongside SDS. This combination results in practical retention times that surpass the performance achieved with either the surfactant or IL alone in the mobile phase. The study particularly emphasises the impact of the IL anion, especially in the absence of SDS and organic solvents. This unveils interactions that are otherwise obscured in micellar and hydro-organic media, providing new insights into chromatographic dynamics.

Modelling the pH dependent retention and competitive adsorption of charged and ionizable solutes in mixed-mode and reversed-phase liquid chromatography

This study investigated the influence of pH on the retention of solutes using a mixed-mode column with carboxyl (-COOH) groups acting as weak cation exchanger bonded to the terminal of C18 ligands (C18-WCX column) and a traditional reversed-phase C18 column. First, a model based on electrostatic theory was derived and successfully used to predict the retention of charged solutes (charged, and ionizable) as a function of mobile phase pH on a C18-WCX column. While the Horváth model predicts the pH-dependent retention of ionizable solutes in reversed-phase liquid chromatography (RPLC) solely based on solute ionization, the developed model incorporates the concept of surface potential generated on the surface of the stationary phase and its variation with pH. To comprehensively understand the adsorption process, adsorption isotherms for these solutes were individually acquired on the C18-WCX and reversed-phase C18 columns. The adsorption isotherms followed the Langmuir model for the uncharged solute and the electrostatically modified Langmuir model for charged solutes. The elution profiles for the single components were calculated from these isotherms using the equilibrium dispersion column model and were found to be in close agreement with the experimental elution profiles. To enable modelling of two-component cases involving charged solute(s), a competitive adsorption isotherm model based on electrostatic theory was derived. This model was later successfully used to calculate the elution profiles of two components for scenarios involving (a) a C18 Column: two charged solutes, (b) a C18 Column: one charged and one uncharged solute, and (c) a C18-WCX Column: two charged solutes. The strong alignment between the experimental and calculated elution profiles in all three scenarios validated the developed competitive adsorption model.

Imbalances in Dissolved Elemental Export Fluxes Disclose “Hidden” Critical Zone Compartments

AbstractIn streams, short‐term element‐specific solute fluxes are often not balanced with long‐term chemical weathering fluxes determined in the residual solids from fractional element loss and denudation rate. The ratio of both estimates—the “Dissolved Export Efficiency” (DEE)—is frequently <1, indicating deficits in the stream dissolved load. To explore the cause of the stream deficits, we performed a daily water sampling campaign for one year in a forested headwater watershed in Southern Germany. We sampled surface runoff, above‐canopy and below‐canopy precipitation, subsurface flow from the organic soil layer, upper, and deep mineral soil, and groundwater. Regolith samples were obtained from a drill core and revealed the weathering front to lie between 7 and 15 m depth. We found a DEE < 1 for K, Si, Al, Fe. These elements are characterized by shallow slopes in C‐Q relationships, and the imbalances were found to originate in the deep saprolite. Their export pathway potentially includes “hidden” Critical Zone compartments or fluxes, presumably unsampled colloids that are exported preferentially during rare flushing events with stochastic temporal distribution. The DEE of nutritive elements like Ca, Mg, and P is also <1. These elements are characterized by steeper C‐Q slopes, and their imbalance can be explained by deep nutrient uptake followed by nutrient retainment in re‐growing forest biomass or export in plant debris. The collective evidence for these imbalances, including previous evidence from metal stable isotopes, suggests that the deep Critical Zone represents the location for chemical or biogenic retention and release of solutes.

Persistence of STEM Majors in Higher Education

Students in STEM programs often face difficult or ‘weed out’ courses in their first year of declaring their major and are frequently confronted with academic threats such as lack of understanding complex concepts, or receiving poor grades. The U.S. is estimated to need at least 1 million more STEM majors to meet the growing job market in STEM fields, and nearly 60% of students who declare a STEM major eventually switch to a non-STEM major or leave without any degree (Turetsky et al., 2020). Drawing on self-affirmation theory, this quantitative study explores the role that academic confidence and a sense of belonging play in STEM major persistence through a lens of self-affirmations. Fifty-four undergraduate students participated in a pre-test/post-test survey with a double-blind affirmation intervention in an introductory chemistry I course. Findings revealed a remarkably high STEM major persistence rate of 102%, but no statistically significant findings, challenging the notion of standalone affirmation interventions as a quick solution for retention. While the intervention did not yield statistically significant results, post-test belonging scores suggest a more significant influence on persistence than academic confidence. The study underscores the complexity of promoting STEM major persistence. Future research could explore longitudinal impacts, additional institutions, and mechanisms underlying student belonging to develop more effective retention strategies.

#3023 Dietary protein intake modulates the tubular handling of the uremic retention solute indoxyl sulfate

Abstract Background and Aims Nutritional intervention constitutes a key part of the clinical management of individuals with chronic kidney disease (CKD). The gut emerged as an important source of uremic retention solutes, including indoxyl sulfate, p-cresyl sulfate and TMAO among the others. Indoxyl sulfate (IS) is produced through the gut microbial fermentation of tryptophan into indole and its conversion into indoxyl sulfate in the liver. Previous authors hypothesised that higher amounts of gut microbial metabolites can be sensed by kidney's proximal tubule cells through the use of receptors and signaling pathways. Particular evidence points to the involvement of kidney Organic Anion Transporters’(OATs') in controlling the gut-kidney communication. According to the so-called remote sensing hypothesis, kidney tubular cells respond to uremic toxins plasma fluctuations altering the activity of OAT1. Few studies have investigated whether in CKD the protein content in the diet affects gut generation, plasma retention and excretion mechanisms of indolic uremic toxins including kidney cells OAT1 expression. Method Eighteen male Sprague-Dawley rats (Janvier, France) aged 7-8 weeks and weighing between 270 and 388 g were randomly assigned to a low protein (LP) diet (n = 10) or a high protein (HP) diet (n = 8) after undergoing a 5/6 nephrectomy to develop CKD. For each diet, a sham-operated control group (n = 7 and n = 8 correspondingly) was used. After 7 weeks, urine was collected, and 8 weeks after the disease was induced, euthanasia was performed. Samples of kidney and blood were taken. mRNA and protein expression of OAT1 were sought via qPCR and Western blot. Forty patients with CKD were recruited in a cross-sectional study investigating eating habits and uremic toxins levels. Eating habits were searched via a food diary. Protein and energy intake were therefore calculated. Blood and 48 h-urine were collected. Blood creatinine and urea were determined with standard laboratory techniques. Total plasmatic and urinary IS concentrations were measured using LC-MS/MS. The fractional excretion (FE) i.e. the percentage of IS excreted relatively to the kidney filtered load, was calculated to assess IS remote sensing. Results Rats with chronic kidney disease (CKD) had considerably higher plasmatic levels of IS (p < .001) than sham rats. Rats with CKD on an HP diet, however, did not differ in plasma IS from rats fed an LP diet (p = .63). On the other hand, CKD rats fed an HP diet showed a substantial rise in 24-hour urinary IS (p < .001). The FE of IS was significantly higher (p = .005) in CKD rats on a HP diet and correlated with 24 h-urinary IS (Spearman r = .51, p value=.03) and with protein intake (Spearman r = .52, p value=.03) in CKD rats. OAT1 mRNA and protein expression was significantly higher in CKD rats given a HP diet (p = .025 and p = .009, respectively). By dividing the CKD patients into two groups by the median of protein intake, the FE of IS was significantly higher (p = .018) in the patients consuming a larger portion of proteins. Conclusion A diet higher in protein content in 5/6 nephrectomized CKD rats as well as in CKD patients likely leads to an increased production of indole in the colon. This results in increased IS fractional excretion but unchanged IS plasma retention. These findings offer more evidence for the mechanisms behind the remote sensing and signaling of uremic toxins derived from indole. In summary, a low-protein diet is still advised for people with chronic kidney disease.

How Resilient are Lucid Motivators? Endeavoring Reforms for Effects of Psycho-social Factors on Workers Health Through Concurrent Engineering

BackgroundAs the tremendous impact of extreme workloads, arduous working conditions, and disorganization disrupt humane job definitions in some industries, the need for workplace re-articulation was interfered to ameliorate psycho-social factors and suggest organizational intervention strategies. Especially for colossally wounded health-care (HC) systems, today it is now even more unrealizable to retain workforce resilience considering the immense impact of overwhelming working conditions. MethodsThis study introduces employment of concurrent engineering tools to re-design humane workplaces annihilating abatement over devoured resources. The study handles HC-workforce resilience in a pioneering motive to introduce transformation of well-known motivators and proposes solutions for retention and resilience issues grounding on HC workers’ own voice. ResultsThe proposed adjustable approach introduces integral use of focus group studies, SWARA, and QFD methods, and was practiced on a real-world case regarding Turkish HC workforce. The paper also presents widespread effects of findings by tendering generalized psycho-social rehabilitation strategies. Results confirmed the modifications of the most potent incessant motivators. Conclusion“Burn out issues” and “Challenging work” were found as the most important motivator and satisfier, respectively, to be exigently fulfilled. Corrective interventions, required resolutions, and workplace articulation connotations were arbitrated in terms of entire outcomes on four dimensions in three different planning periods considering the current status, repercussions of pandemic, and contingency of similar catastrophes. Descriptive illustrations were additionally presented to support deducted interpretations.

IGC investigation of the effect of the length of the n-alkyl substituent in 5-alkylsubstituted norbornenes on solute retention

Polymerization of 5-n-alkyl-substituted 2-norbornenes synthesized a series of polymers having the same structure of the main polymer chain, but differing in the length of the alkyl substituent (up to 14 methylene units). The obtained polymers were studied by the capillary IGC method as a stationary phase during separation of a mixture of normal hydrocarbons C6-C10. Retention data in the form of a logarithm of the retention factor lnk were correlated with the size of the sorbate (via the carbon number of the alkane ZS) and with the size of the n-alkyl substituent in the polymer chain (via the carbon number of the polymer ZP). Correlation of lnk vs. ZS turned out to be linear for all polymers, but the angle of the slope of linear dependence dlnk/dZS increases with a decrease in the carbon number of the polymer ZP. Dependency of dlnk/dZS vs. ZP is not linear and indicates an increase in the retention of sorbates by the stationary phase with a decrease in the length of the alkyl substituent in the polymer chain. The correlation of the retention of lnk analytes with the carbon number of the polymer ZP is not linear and indicates an increase in the sorbate/sorbent interaction with a decrease in the length of the alkyl substituent. Inflection points were found at both correlations with ZP in the region of ZP = 8, which indicates a possible change in the sorption mechanism or a change in the phase state of the polymer. In polymer chemistry, the phase state of a polymer is characterized by the glass transition temperature Tg, the dependence of which vs. ZP turned out to be nonlinear with an inflection point at ZP ∼11. Thus, a decrease in the length of the alkyl substituent leads to the transition of the polymer from a rubbery state to a glassy one at ZP ∼ 11, which in turn, with a further decrease in the carbon number of the polymer to ZP ∼ 8, causes a change in the sorption mechanism from bulk sorption to surface sorption. The change in the sorption mechanism is accompanied by an increase in the interaction of the sorbate with the stationary phase, which manifests itself both in an increase in the retention time of analytes and in an increase in the enthalpy and entropy of sorption. The reason for this increase can be seen in the formation of a microporous structure in 5-alkyl-substituted polynorbornenes in a glassy state.

Prevalence of dysmagnesemia among CKD patients in North India

Prevalence of dysmagnesemia among CKD patients in North India

Post-translational modifications in kidney diseases and associated cardiovascular risk.

Patients with chronic kidney disease (CKD) are at an increased cardiovascular risk compared with the general population, which is driven, at least in part, by mechanisms that are uniquely associated with kidney disease. In CKD, increased levels of oxidative stress and uraemic retention solutes, including urea and advanced glycation end products, enhance non-enzymatic post-translational modification events, such as protein oxidation, glycation, carbamylation and guanidinylation. Alterations in enzymatic post-translational modifications such as glycosylation, ubiquitination, acetylation and methylation are also detected in CKD. Post-translational modifications can alter the structure and function of proteins and lipoprotein particles, thereby affecting cellular processes. In CKD, evidence suggests that post-translationally modified proteins can contribute to inflammation, oxidative stress and fibrosis,and induce vascular damage or prothrombotic effects, which might contribute to CKD progression and/or increase cardiovascular risk in patients with CKD. Consequently, post-translational protein modifications prevalent in CKD might be useful as diagnostic biomarkers and indicators of disease activity that could be used to guide and evaluate therapeutic interventions, in addition to providing potential novel therapeutic targets.

Fabrication of anti-fouling membranes of polyvinylidene fluoride (PVDF) with the addition of cellulose nanofibers (CNF)

In this study, cellulose nanofibers (CNF) were synthesized for the fabrication of polyvinylidene fluoride (PVDF) membranes using the non-solvent-induced phase separation (NIPS) technique with distilled water as the non-solvent. The hybrid membranes exhibited an asymmetric morphology, along with increased porosity and hydrophilicity with the rising concentration of CNFs. Thermal analysis revealed that all membranes are thermally stable up to approximately 430 °C, indicating their viability for high-temperature applications. Filtration tests demonstrated an enhanced permeate flux and albumin retention with the addition of CNF. The membrane with 1.5 wt% CNF increased solute retention by 19.67 % compared to the PVDF membrane. Furthermore, the hybrid membranes exhibited improved flow recovery rates and a reduction in irreversible fouling. These findings underscore the hydrophilic and anti-fouling properties of the membranes produced in this study, making them a promising solution to enhance the efficiency and sustainability of filtration and separation processes. Their significant potential for water treatment applications in the near future is highlighted.

Design optimization of hemodialyzer membrane modelled in chemical reaction module using statistical algorithms and ANOVA testing

High performing hemodialyzers membranes such as high flux membranes, high cut-off membranes and medium cut-off membranes are always at research interest due to their better efficiency than conventional membranes. These membranes provide greater toxin clearance, however retention of essential solutes in a preferable way are still under study. This paper aims at the design of high performing membrane to study the role of its parameters in solute removal and its capability of holding back important molecules. One of the most effective design of experiments (DOE) tool, namely Taguchi Algorithm was used for the formation of fractional factorial design of parameters. The simulation results were benchmarked with that of experimental data from literature and with manufacturers data sheets. Once the benchmarking was done, the error quantification and significance of each design were analysed using statistical method, Analysis of Variance (ANOVA) testing. The most relevant parameters that helped in better clearance in these membranes were thus identified and substantial conclusions were drawn which can be used in the future for designing optimal dialyzer designs. Results shows that clinically used dialyzer membranes such as RevaclearMax and FxCorDiax series on modelling using COMSOL Multiphysics with a blood flow rate of 400 ml/min and dialysate flow of 500 ml/min showed better urea clearance rate of above 300 indicating that the membranes thus designed was superior to the conventional high flux membranes that have a clearance rate of 297 of less for the exact same functional, geometrical, and parametric conditions. The model replication and thus validation of the design helped in understanding the influence of various parameters in toxin clearance. These parameters can be further investigated, and optimal models can be delivered with more of clinical examinations and trials.