A multi-physics modelling tool for Reverse Electrodialysis

In this work, a multi-physics modelling approach has been developed for the RED process

Investigation of Reverse ElectroDialysis Units by Multi-Physical Modelling

Reverse electrodialysis (RED) is an electrochemical membrane process that converts the salinity gradient energy between two solutions into electric current, by using ion exchange membranes. A novel multi-physical approach for RED modelling is proposed. 2-D simulations of one cell pair with tertiary current distribution (Nernst\u2013Plank equation and local electroneutrality) were performed. Moreover, the Donnan exclusion theory was implemented for simulating double layer phenomena. Transport phenomena and electrochemical behavior were well described. The influence of membrane/channel configuration, dilute concentration and feeds velocity on the process performance was assessed. For a dilute concentration 64 0.01M, stacks with profiled membranes reached lower resistances and higher net powers (up to 4.4 W/m2) with respect to stacks with empty channels, thus suggesting that only in some cases the profiles lead to a performance enhancement

Relationship between prolactin plasma levels and white matter volume in women with multiple sclerosis

BACKGROUND: The role of prolactin (PRL) on tissue injury and repair mechanisms in multiple sclerosis (MS) remains unclear. The aim of this work was to investigate the relationship between PRL plasma levels and brain damage as measured by magnetic resonance imaging (MRI). METHODS: We employed a chemiluminescence immunoassay for measuring plasma levels of PRL. We used a 1.5 T scanner to acquire images and Jim 4.0 and SIENAX software to analyse them. RESULTS: We included 106 women with relapsing remitting (RR) MS and stable disease in the last two months. There was no difference in PRL plasma levels between patients with and without gadolinium enhancement on MRI. PRL plasma levels correlated with white matter volume (WMV) (rho = 0.284, p = 0.014) but not with grey matter volume (GMV). Moreover, PRL levels predicted changes in WMV (Beta: 984, p = 0.034). CONCLUSIONS: Our data of a positive association between PRL serum levels and WMV support the role of PRL in promoting myelin repair as documented in animal models of demyelination. The lack of an increase of PRL in the presence of gadolinium enhancement, contrasts with the view considering this hormone as an immune-stimulating and detrimental factor in the inflammatory process associated with MS

CPX-351 treatment in secondary acute myeloblastic leukemia is effective and improves the feasibility of allogeneic stem cell transplantation: results of the Italian compassionate use program

Secondary acute myeloid leukemia (sAML) poorly responds to conventional treatments and allogeneic stem cell transplantation (HSCT). We evaluated toxicity and efficacy of CPX-351 in 71 elderly patients (median age 66 years) with sAML enrolled in the Italian Named (Compassionate) Use Program. Sixty days treatment-related mortality was 7% (5/71). The response rate at the end of treatment was: CR/CRi in 50/71 patients (70.4%), PR in 6/71 (8.5%), and NR in 10/71 (19.7%). After a median follow-up of 11 months relapse was observed in 10/50 patients (20%) and 12 months cumulative incidence of relapse (CIR) was 23.6%. Median duration of response was not reached. In competing risk analysis, CIR was reduced when HSCT was performed in first CR (12 months CIR of 5% and 37.4%, respectively, for patients receiving (=20) or not (=30) HSCT, p = 0.012). Twelve-months OS was 68.6% (median not reached). In landmark analysis, HSCT in CR1 was the only significant predictor of longer survival (12 months OS of 100 and 70.5%, for patients undergoing or not HSCT in CR1, respectively, p = 0.011). In conclusion, we extend to a real-life setting, the notion that CPX is an effective regimen for high risk AML patients and may improve the results of HSCT

Investigating the phenomenon of "cognitive-motor interference" in multiple sclerosis by means of dual-task posturography

BACKGROUND: Two simultaneously performed tasks may compete for common brain network resources in patients with multiple sclerosis (MS), suggesting the occurrence of a cognitive-motor interference. While this phenomenon has been well described for walking and gait, data on static balance are scarce. METHODS: In this cross-sectional study, 92 patients and 46 sex/age-matched healthy controls (HCs) were tested by means of static posturography under eyes opened (single-task condition) and while performing the Stroop word-colour task (dual-task condition), to estimate the dual-task cost (DTC) of standing balance. The patient group also underwent the Expanded Disability Status Scale, 25-foot walking test, 12-item MS walking scale, Modified Fatigue Impact Scale, and Symbol Digit Modalities Test. RESULTS: Patients had larger postural sway under both single-task and dual-task conditions (p<0.001), as well as greater DTC of standing balance (p=0.021) than HCs. Although secondary progressive (SP) patients had larger sway in both conditions than relapsing-remitting (RR) patients (p<0.05), these latter ones exhibited a greater DTC of postural balance (p=0.045). Deficits in sustained attention and information processing speed, as assessed by the SDMT, were also independently associated with the magnitude of DTC of standing balance (p=0.005). CONCLUSIONS: The phenomenon of cognitive-motor interference might be unmasked by a dual-task posturography and was associated with impaired sustained attention and information processing speed, especially in RR patients. The smaller DTC of standing balance observed in SP patients may be due to the ceiling effect of postural sway, or alternatively to the lack of postural reserve which constrained the more disabled patients to prioritize the balance over the cognitive task

Exergy analysis of electrodialysis for water desalination: Influence of irreversibility sources

The increasing freshwater demand is pushing the development and adoption of desalination technologies. In this framework, electrodialysis has a consolidated role in brackish water desalination, but to make it competitive with other technologies for the desalination of more concentrated solutions (e.g., seawater), the specific energy consumption should be reduced. Exergy analysis provides a useful tool for determining the contribution of each thermodynamic inefficiencies on the process efficiency and the specific energy consumption. In this regard, this paper presents an exergy analysis of the electrodialysis process. A 1-D model is used for evaluating the performance of industrial-scale systems, consisting of a single or a double-stage configuration, and fed by brackish water, concentrated brackish water, or seawater. The analysis is devoted to quantifying the effects of irreversibility sources, focusing especially on the non-ideal membrane behavior. Results highlight that the ohmic resistance of solutions and membranes along with undesired transport phenomena play a major role. More specifically, passing from an “ideal” to a “real” process, the maximum value of the exergy efficiency decreases by about 6% in the case of brackish water and 16% in the case of seawater. Besides, results reveal that the water permeability of membranes is detrimental to the exergy efficiency, leading to an 8% reduction in the case of seawater desalination. The development of improved membranes with low resistances slightly enhances the exergy efficiency with negligible influence on the performance of the system. The adoption of the double-stage strongly reduces the specific exergy consumption, and in the second stage, the exergy destruction due to uncontrolled mixing phenomena becomes more important than the one caused by the membrane resistance. The results shed a light on the main actions to be undertaken by industries and engineers for improving the performance of electrodialysis systems

Multi-physical modelling of Reverse ElectroDialysis

Energy extraction from salinity gradients (salinity gradient power, SGP) represents a novel and valuable renewable energy source. Among the existing SGP technologies, reverse electrodialysis (RED) is the oldest and one of the most promising. RED is a membrane-based electrochemical process that directly converts the salinity gradient energy into electric current. More precisely, in a RED unit two solutions at different concentration flow in two series of alternated channels, which are formed by piling two alternated series of cation and anion exchange membranes (CEMs and AEMs, respectively). The chemical potential difference between the two solutions generates an electric potential difference over each membrane along with a selective transport of cations (across CEMs) and anions (across AEMs) from each concentrate channel towards the two contiguous dilute ones. Eventually, the so generated ionic current is converted by redox reactions into an electric current in the two electrode compartments closing the stack. RED is characterized by a number of different physical phenomena, which should be properly modelled in order to drive the process design and optimization. In this regard, this work presents a novel approach for multi-physical modelling of the entire RED process. A single 2-D cell pair (encompassing two membranes and two feed channels) is the identified process repeating unit, coinciding with the computational domain investigated. In order to fully cover the phenomenological complexity of the operation of a RED unit, a number of different physical models were implemented and interconnected each other. In particular: (i) Navier–Stokes and continuity equations were solved for fluid dynamics modelling; (ii) Nernst–Plank equation was used for ion mass transfer; (iii) local electroneutrality condition was assumed everywhere, taking also into account the fixed charges concentration within the membranes. At membrane-solution interfaces: (iv) Donnan exclusion theory was applied to simulate voltage jump; (v) partition coefficients were adopted to simulate concentration jump. Finally, the model is completed by (vi) algebraic equations for the calculation of stack potential, current density and gross / net power density in a stack of any given number of cell pairs, by taking into account also the electrode compartments resistance and the external load variation. As model outputs, the distributions of velocity, pressure, concentrations, fluxes and potential in the overall domain were obtained, and the values of gross and net power density were computed. Different membrane/channel configurations were investigated, including flat membranes, either with or without non-conductive spacers, and profiled membranes. Moreover, the influence of the feeds concentration was evaluated. The model developed appears to be a promising tool for the optimization of RED units design and operatio