Nonideal Selectivity Research Articles

Upscaling Salinity Gradient CRED Cell for Blue Energy Harvesting

CRED (Capacitive reverse electrodialysis) cells are a hybrid technology that were originally introduced by David A. Vermaas to extract electrical energy from salinity gradient [1]. They use selective IME (ion membranes exchange) just like RED (Reverse Electrodialysis) systems but borrow long-lasting, non-faradaic and inexpensive capacitive electrodes from Capmix (Capacitive Mixing) systems achieving power densities around 0.9 W/m² of IME - 5 times higher than Capmix systems [2] but 2 times lower than RED systems [3].Since then, we reviewed this CRED cell in the MIE lab in order to simplify and optimize it. The current system designed by Youcef BRAHMI [4] only uses one IME and carbon felts as capacitive electrodes (Figure 1). The whole cell is equivalent to an ideal generator Ecell, an internal resistance Rcell and an internal capacitor C in series (Figure 2b). Due to the charge of the internal capacitor, the cell must be used in an alternative regime by switching the concentrated and diluted solutions of sodium chloride over a half-period T (Figure 2a). The uptake of these 3D electrodes increases drastically the capacitance allowing us to achieve around 2.3 W/m² by stabilizing the potential (Middle of Figure 5); which can even reach 3.3 W/m² by choosing an appropriate half-period and reducing the internal resistance by employing thinner membranes and higher concentrations (Figure 2e) [5]. Yet, this still represents about 2/3 of the maximum theoretical power obtained for a square potential generator like in RED systems. The maximal power is obtained for loading resistances Rload slightly higher than Rcell (Figure 2d).Very recently, Nan Wu proposed a very surprising technique to recover around 90% of the theoretical power density [5]. She used an additional power supply in phase with the fluid switching (Figure 3). For a given half-period, using this boosting technique ads 60% of the power compared to the non-boosting functioning after retrieving the power contribution of the external source (Figure 4). The boosting acts formally like an additional resistance that increases the characteristic time of the RC circuit stabilizing the whole cell potential at its highest value. It also allows to work with higher external resistances (up to 10 times).Currently, our techno-economic analysis estimates that our cell can produce energy at a cost of 200 €/MWh in the best conditions [6]. Given the decrease of the cost of the IME, these systems could become quite soon a profitable renewable energy. This motivates us in building a cell capable of producing 50 W. For that, we will upscale our CRED cell. The first approach is to increase the surface of a single membrane. We will focus on the effect of the extension of the length - along the flow - and the width – perpendicular to it. The extension of the length highlights the problem of the filling time that has to be as short as possible in order to reach the maximal potential as quick as possible and approach a square signal while not spending too much energy fighting viscous dissipations. Extending the length also amplifies the non-ideal selectivity of the membrane requiring an adjustment of the relative volume flows of the saline solutions. Preliminary results showed that during a switch, the potential of the cell is mostly given by the Donnan potential and its spatial mean considering a plug flow (Figure 5). Regarding the width, the mechanism is different. As the system displays an invariance regarding the flow, the main goal is to improve the transmission line along the current collectors that sets a limit width due to the linear resistance of the collectors. Increasing the surface of one membrane helps reducing the total inner resistance of the cell resulting in a higher current. We will then associate in series the CRED cells to obtain cumulative potential and power while preserving power density on small cells (Figure 6) [7].[1] D. A. Vermaas et al., Energy & Environmental Science, 2013[2] F. Liu et al., Energy & Environmental Science, 2012[3] D. A. Vermaas et al., Environmental Science & Technology, 2011[4] Y. Brahmi et al., Energy Conversion and Management, 2022[5] N. Wu et al., Environmental Science & Technology, 2023[6] N. Wu et al., Scientific Reports, 2024 (Under Review)[7] Z. MAN, PhD Student, 2023 - Now Figure 1

The role of single‐walled carbon nanotubes functionalized with gold to increase radiosensitivity of cancer cells to X‐ray radiation

The improvement of high‐Z‐based metallic nanostructures as radiosensitizers with high monolithicity and versatility by superadditive therapeutic track and the good protective effect is considerable, but they are limited by some problems such as nonideal selectivity for the target tissue. In this study, nanosystems were developed to enhance the efficacy of radiotherapy and reduce cancer cell survival based on innovative gold (Au) functionalized oxygen‐single‐walled carbon nanotubes (O‐SWCNTs). We illustrate the use of folic acid (FA) as a targeting agent and bovine serum albumin (BSA) to stabilize the physiological environment and increase durability. The physical and chemical properties of the nanosystems were evaluated using transmission electron microscopy (TEM), selected area electron diffraction (SAED), dynamic light scattering (DLS), zeta potential, X‐ray diffraction (XRD), ultraviolet–visible (UV–Visible), and Fourier transform infrared (FTIR) techniques. Finally, the MTT assay was used to investigate the therapeutic effects of nanoparticles in the 4 T1 mouse breast cancer model in the presence and absence of X‐rays. So, the cancer cells experienced a more effective reduction in survival after receiving O‐SWCNTs‐Au‐BSA‐FA + 8 Gy than O‐SWCNTs‐BSA, Au‐BSA‐FA, and O‐SWCNTs‐Au‐BSA + 8 Gy groups.

A multi-ion interference decoupling model based on ion-selective electrode arrays.

Compared to traditional liquid-junction ion-selective electrodes, solid-contact ion-selective electrodes (SC-ISEs) have attracted much attention and undergone rapid development due to their compactness and ease of integration. However, the application and widespread use of SC-ISEs are limited by their non-ideal selectivity and susceptibility to signal drift. Although the principles of artificial neural network (ANN) methods have shown significant progress in partially resolving the selectivity issue, they generally require extensive calibration steps and computational resources to implement. As a result, numerical computation models are more practical and economical, but existing approaches often overlook experimental phenomena and have relatively complex modeling principles. In this study, we propose a proportional factor model based on the trend of SC-ISEs affected by the multiple ions, along with a scalable dynamic correction procedure to improve its robustness. This model utilizes an estimated response surface method to solve nonlinear equations, requiring fewer calibration experiments. It accurately extracts the concentrations of multiple target ions in the presence of multi-ion interference and dynamically adjusts the model parameters for different types of ISEs. Additionally, we design a multi-channel SC-ISE array as a carrier for theoretical validation. In a case study, we demonstrate the feasibility of decoupling multiple ions using the SC-ISE array, obtaining concentrations of calcium, magnesium, sodium, and potassium ions, and verify the accuracy of the multi-ion detection system for real-world water samples.

Electrodialysis Desalination with Simultaneous pH Adjustment Using Bilayer and Bipolar Membranes, Modeling and Experiment.

A kinetic model of the bipolar electrodialysis process with a two-chamber unit cell formed by a bilayer (bipolar or asymmetric bipolar) and cation-exchange membrane is proposed. The model allows describing various processes: pH adjustment of strong electrolyte solutions, the conversion of a salt of a weak acid, pH adjustment of a mixture of strong and weak electrolytes. The model considers the non-ideal selectivity of the bilayer membrane, as well as the competitive transfer of cations (hydrogen and sodium ions) through the cation-exchange membrane. Analytical expressions are obtained that describe the kinetic dependences of pH and concentration of ionic components in the desalination (acidification) compartment for various cases. Comparison of experimental data with calculations results show a good qualitative and, in some cases, quantitative agreement between experimental and calculated data. The model can be used to predict the performance of small bipolar membrane electrodialysis modules designed for pH adjustment processes.

Biomimetic nanotherapeutics based on oxygen supply and ultrasmall Cu-Se-Au alloy nanoparticles for boosting radio-photothermal ablation of breast cancer

Radiotherapy (RT) is one of the important tools for clinical treatment of breast cancer. Currently, some nanoradiosensitizers have been developed for augmenting the therapeutic efficiency of RT. However, some limitations still exist for their further applications, such as oxygen dependence in hypoxic tumors, nonideal selectivity for tumors, and inevasible damages to normal tissues. To resolve these problems, a biomimetic nanoplatform was developed for efficient co-loading and precise co-delivery of oxygen and nanoradiosensitizer by taking advantage of large pore volumes and easy surface modification of dendritic large pore mesoporous silica nanoparticles (DLMSNs). The outer surfaces of DLMSNs were modified with citric acid for attaching firmly and chelating stably with ultrasmall Cu-Se-Au alloy nanoparticles possessing distinct radiosensitizing and photothermal conversion performances. The inner surfaces of DLMSNs were modified with perfluorosilane for loading perfluorohexane that has extraordinary oxygen-carrying capability to alleviate tumor hypoxia. White blood cells membranes were wrapped onto the surfaces of the resultant DLMSNs for promoting co-delivery of therapeutic agents targeting to tumor and reducing injuries to normal tissues. Biomimetic nanotherapeutic system thus prepared showed powerful suppression effects against breast cancer both in vitro and in vivo by intelligently integrating tumor-targeted delivery, oxygen supply, radiosensitizing and photothermal ablation.

Folic Acid Modified Bismuth Sulfide and Gold Heterodimers for Enhancing Radiosensitization of Mice Tumors to X-ray Radiation

The development of high-Z based metallic nanomaterials as radiosensitizers are limited due to having some challenges such as nonideal selectivity to the target tissue. In this work, we prepared X-ray triggered Bi2S3-Au heterodimers with a Schottky barrier and hopeful capability of the generation of free radicals for selectively improving radiotherapeutic efficacy in the tumors via not complicated and environmentally friendly methods. We explain the use of folic acid (FA) functionalized, BSA-modified Bi2S3-Au heterodimers (i.e., Bi2S3-Au-BSA-FA hybrids) as a targeted radiosensitizer for breast cancer therapy in the murine model. In addition to that, FA could give a tumor targeting ability, and the BSA coating could prolong circulation time ability to this hybrid system. The FA functionalized Bi2S3-Au heterodimer demonstrated in vitro and in vivo tumor enhanced radio sensitization. When the tumors were irradiated 24 h after receiving the Bi2S3-Au-BSA-FA hybrids, not only significant tumor inhibition was seen but also the survival ratio was increased in mice. Furthermore, the tumor bearing mice experienced a more effective tumor rejection when they received Bi2S3-Au-BSA-FA hybrids + X-ray irradiation than both of the Bi2S3-BSA + X-ray and Au + X-ray groups.

Habitat selection in transformed landscapes and the role of forest remnants and shade coffee in the conservation of resident birds.

Biodiversity conservation in transformed landscapes is becoming increasingly important. However, most assessments of the value of modified habitats rely heavily on species presence and/or abundance, masking ecological processes such as habitat selection and phenomena like ecological traps, which may render species persistence uncertain. High species richness has been documented in tropical agroforestry systems, but comparisons with native habitat remnants generally lack detailed information on species demography and habitat use. We generated a multi-species, multi-measure framework to evaluate the role of habitat selection in the adaptation of species to transformed landscapes, and demonstrate that its use could affect how we value the contribution different land uses make to biodiversity conservation. We analysed 7years of capture-mark-recapture and observation data for twelve species of resident birds present in native forest remnants and shade coffee plantations in a mega-diverse region. We assessed whether species behaved adaptively by evaluating the correlation between measures of habitat preference (occurrence, abundance, fidelity, inter-seasonal variance and age) and performance (body condition, muscle, primary moult, breeding and juveniles) in forest and coffee, and generated hypotheses about their role in species persistence. We documented adaptive habitat selection for seven species, non-ideal selection for four and maladaptive selection for one. While many species showed equal preference and/or equal performance in many traits, in general we found more evidence for birds preferring and/or performing better in forest than coffee, although relationships between our indicators and population adaptation need to be studied further before our proposed framework can be applied to more species and landscapes. While shade coffee can act as a biodiversity-friendly matrix providing complementary or supplementary habitat to a wide range of resident bird species, protecting remnants of native vegetation is still of paramount importance for biodiversity conservation in agricultural landscapes.

Enhanced Generation of Non-Oxygen Dependent Free Radicals by Schottky-type Heterostructures of Au-Bi2S3 Nanoparticles via X-ray-Induced Catalytic Reaction for Radiosensitization.

Despite the development of nanomaterials with high-Z elements for radiosensitizers, most of them suffer from their oxygen-dependent behavior in hypoxic tumor, nonideal selectivity to tumor, or inevasible damages to normal tissue, greatly limiting their further applications. Herein, we develop a Schottky-type heterostructure of Au-Bi2S3 with promising ability of reactive free radicals generation under X-ray irradiation for selectively enhancing radiotherapeutic efficacy by catalyzing intracellular H2O2 in tumor. On the one hand, like many other nanomaterials with rich high-Z elements, Au-Bi2S3 can deposit higher radiation dose within tumors in the form of high energy electrons. On the other hand, Au-Bi2S3 can remarkably improve the utilization of a large number of X-ray-induced low energy electrons during radiotherapy for nonoxygen dependent free radicals generation even in hypoxic condition. This feature of Schottky-type heterostructures Au-Bi2S3 attributes to the generated Schottky barrier between metal Au and semiconductor Bi2S3, which can trap the X-ray-generated electrons and transfer them to Au, resulting in efficient separation of the electron-hole pairs. Then, because of the matched potential between the conduction band of Bi2S3 and overexpressed H2O2 within tumor, the Au-Bi2S3 HNSCs can decompose the intracellular H2O2 into highly toxic •OH for selective radiosensitization in tumor. As a consequence, this kind of nanoparticle provides an idea to develop rational designed Schottky-type heterostructures as efficient radiosensitizers for enhanced radiotherapy of cancer.

Linking habitat selection and predation risk to spatial variation in survival

1. A central assumption underlying the study of habitat selection is that selected habitats confer enhanced fitness. Unfortunately, this assumption is rarely tested, and in some systems, gradients of predation risk may more accurately characterize spatial variation in vital rates than gradients described by habitat selection studies.2. Here, we separately measured spatial patterns of both resource selection and predation risk and tested their relationships with a key demographic trait, adult female survival, for a threatened ungulate, woodland caribou (Rangifer tarandus caribou Gmelin). We also evaluated whether exposure to gradients in both predation risk and resource selection value was manifested temporally through instantaneous or seasonal effects on survival outcomes.3. We used Cox proportional hazards spatial survival modelling to assess the relative support for 5 selection- and risk-based definitions of habitat quality, as quantified by woodland caribou adult female survival. These hypotheses included scenarios in which selection ideally mirrored survival, risk entirely drove survival, non-ideal selection correlated with survival but with additive risk effects, an ecological trap with maladaptive selection and a non-spatial effect of annual variation in weather.4. Indeed, we found positive relationships between the predicted values of a resource selection function (RSF) and survival, yet subsequently incorporating an additional negative effect of predation risk greatly improved models further. This revealed a positive, but non-ideal relationship between selection and survival. Gradients in these covariates were also shown to affect individual survival probability at multiple temporal scales. Exposure to increased predation risk had a relatively instantaneous effect on survival outcomes, whereas variation in habitat suitability predicted by an RSF had both instantaneous and longer-term seasonal effects on survival.5. Predation risk was an additive source of hazard beyond that detected through selection alone, and woodland caribou selection thus was shown to be non-ideal. Furthermore, by combining spatial adult female survival models with herd-specific estimates of recruitment in matrix population models, we estimated a spatially explicit landscape of population growth predictions for this endangered species.

Separation of weak and strong acids by electro-electrodialysis—Experiment and theory

The experimental results of the separation of acetic acid (HA) from the sulfuric acid by the electro-electrodialysis (EED) method and the modeling of process have been presented. The Neosepta membranes CMX and ACM have been used. It has been found that the efficiency of retention of HA is high (>0.9) when the process is conducted below the limiting current density with respect to HSO 4 − or SO 4 2− anions. The observed current efficiency of the H 2SO 4 removal was rather low ( CE S = ca. 0.7, when the initial concentration of H 2SO 4 in the mixture was 1 or 2 M) which was caused by the nonideal selectivity of the anion-exchange membrane. The experimental results have been described by the model based on the extended Nernst-Planck equation and the Donnan equilibrium. Since the efficiency of the process depended mainly on the selectivity of anion-exchange membrane (ACM), the concentration of fixed charges of that membrane, c ¯ m , and the ratio of volume fraction of pores to their squared tortuosity, V p/θ 2, have been chosen as the main fitting parameters. It has been found that the fitting of the EED data depends mainly on c ¯ m , whereas in the modeling of diffusion experiment (or an EED experiment conducted at low current density) both parameters are important. The best fit has been obtained for c ¯ m = 0.5 − 0.6 M , i.e. ca. one order smaller than that determined experimentally. The obtained optimal value of V p/θ 2, equal to 0.013, is consistent with those previously obtained for other Neosepta anion-exchange membrane.

NONIDEAL BREEDING HABITAT SELECTION: A MISMATCH BETWEEN PREFERENCE AND FITNESS

The selection of breeding sites in heterogeneous habitats should ideally be based on cues closely reflecting habitat quality and thus predicting realized individual fitness. Using long-term population data and data on territory establishment of male Northern Wheatears (Oenanthe oenanthe), we examined whether territory characteristics linked to individual fitness (reproductive performance and survival) also were linked to territory preference. Breeding territories varied in their physical characteristics and their potential effects on reproductive performance, and this variation among territories was correlated from one year to the next. Of all measured territory characteristics (from the focal and the previous year) only territory field layer height predicted individual fitness, i.e., reproductive performance was higher in territories with permanently short rather than growing field layers. Territory preference, instead, was only linked to the size of territory aggregations, i.e., males settled earlier at territory sites sharing borders with several adjacent sites than at those with few or no adjacent sites. This mismatch between territory characteristics linked to fitness and those linked to territory preference was not explained by site fidelity or compensated for by the different fitness components measured. Because the results were not in agreement with an ecological trap scenario, where poor habitats are preferred over high-quality habitats, our results suggest a more general case of nonideal habitat selection. Whereas nonideal selection with respect to territory field layer height may be explained by its poor temporal predictability within the breeding season, the preference for territory aggregations is still open to alternative adaptive explanations. Our study suggests that nonideal habitat selection should be investigated by direct estimates of preferences (e.g., order of territory establishment) and their links to habitat characteristics and fitness components. Furthermore, we suggest that the probability of establishing a territory needs to be included as a factor influencing patterns of habitat selection.

Overcoming the Problem of Non-Ideal Liquid Ion Exchanger Selectivity in Microelectrode Ion Flux Measurements

Ion-selective microelectrodes are a powerful tool in studies on various aspects of cell membrane biology in both animal and plant tissues. Further application of this technique is, however, limited to a large extent by the problem of non-ideal selectivity of the liquid ion exchanger used in the preparation of microelectrodes for ion flux measurements. Because of this problem, which is persistent in many commercial liquid ion exchangers, the microelectrode does not discriminate between the ion of interest and other interfering ions (for example, Mg2+ and Ca2+; Na+ and K+), thereby leading to inaccurate concentration readings and, consequently, inaccurate flux calculations. In this work we show that the existing analytical procedure to overcome this problem, using the inverted Nicolsky-Eisenman equation, is inadequate, and suggest an alternative analytical procedure that can be applied directly to the data obtained with commercially available liquid ion exchangers. We show that this alternative procedure allows accurate measurement of ionic concentrations with non-ideal ion-selective microelectrodes in the presence of interfering ions, and illustrate the method by direct experiment using Ca2+ and Mg2+ as a "case study". Several more examples are given, further illustrating practical applications of the method for study of plant responses to salinity, osmotic and reactive oxygen species stresses.

Optimum bit allocation in subband coding with nonideal reconstruction filters

Subband perceptual audio coding aims at providing the best subjective quality by decomposing the input signal into adjacent subbands. Every frequency component is then separately coded with a different number of bits in order to properly shape the quantization noise density power spectrum. In this letter, an optimum bit allocation algorithm is presented. As well as being applicable to either uniform or nonuniform frequency decompositions, it allows us to take into account the nonideal selectivity of the reconstruction filters. The effects of leakage for both short and long FIR filters have been investigated referring to a wavelet packet subband decomposition.

Ultrafiltration in a pipe filter with gelation

We investigate the process of unsteady-state ultrafiltration with gelation under laminar flow conditions in a pipe filter with nonideal selectivity of its membrane.

Effect of gel formation on the process of laminar continuous-flow ultrafiltration

We investigate the process of ultrafiltration with gel formation in laminar flow in a plane channel in the case of nonideal selectivity of the membrane.

Simultaneous quantification of carbon monoxide and methane in humid air using a sensor array and an artificial neural network

Abstract The simultaneous quantification of carbon monoxide and methane in humid air is presented. The response of a three-sensor array, including an undoped and a platinum doped tin dioxide sensor showing non-ideal selectivity and a humidity sensor is fed into an optimised feed forward back propagation artificial neural network in order to obtain the carbon monoxide and methane concentration as network output. The gaseous environments under study were ternary mixtures in the concentration ranges of 0–0.5% methane, 0–1000 ppm carbon monoxide and 0–60% relative humidity at 20°C. The network structure, network output with respect to a priori known test concentrations and the influence of the size of the training data set is discussed.

Single chloride-selective channels active at resting membrane potentials in cultured rat skeletal muscle

The patch-clamp technique was used to characterize channels that could contribute to the resting Cl-conductance in the surface membrane of cultured rat skeletal muscle. Two Cl- -selective channels, in addition to the Cl- -selective channel of large conductance described previously (Blatz and Magleby, 1983), were observed. One of these channels had fast kinetics and a conductance of 45 +/- 1.8 pS (SE) in symmetrical 100 mM KCl. The other had slow kinetics and a conductance of 61 +/- 2.4 pS. The channel with fast kinetics typically closed within 1 ms after opening and flickered between the open and shut states. The channel with slow kinetics typically closed within 10 ms after opening and displayed less flickering. Both channels were active in excised patches of membrane held at potentials similar to resting membrane potentials in intact cells, and both were open a greater percentage of time with depolarization. Under conditions of high ion concentrations, both channels exhibited nonideal selectivity for Cl- over K+ with the permeability ratio PK/PCl of 0.15-0.2. Additional experiments on the fast Cl- channel indicated that its activity decreased with lowered pHi and that SO2-4 and CH3SO-4 were ineffective charge carriers. These findings, plus the observation that the fast Cl- channel was also active in membrane patches on intact cells, suggest that the fast Cl- channel provides a molecular basis for at least some of the resting Cl- conductance. The extent to which the slow Cl- channel contributes is less clear as it was typically active only after excised patches of membrane had been exposed to high concentrations of KCl at the inner membrane surface.