Changes In Ionic Conductivity Research Articles

Influence of PEG plasticizer content on the proton-conducting PEO:MC-NH4I blend polymer electrolytes based films

Plasticized blend polymer electrolytes comprising of polyethylene glycol (PEG) as the plasticizing agent in polyethylene oxide (PEO)-methylcellulose (MC) blended polymer loaded ammonium iodide (NH4I) were prepared by standard solvent cast technique. Impedance analysis was used to detect the change in ionic conductivity due to incorporating various stoichiometric of PEG in the matrix. The diameter of the Cole-Cole plots semicircle decreased with increasing temperature, while the inclination of the spike region increased with increasing temperature, indicating the reduction in bulk resistance. Plasticized blend polymer electrolyte incorporated with 10 wt% of PEG was found to exhibit higher ionic conductivity of 3.37 × 10−3 S.cm−1. Temperature- and frequency-dependence of conductivity is found to follow Vogel Tammann Fulcher's relation and Jonscher power law, respectively. The unplasticized sample follows the overlapping large polaron tunneling (OLPT) model, whereas the highest conducting plasticized sample exhibits the non-overlapping small polarons (NSPT) model. The dielectric constants increase continuously with an increase in temperature due to increases in the polarization which leads to high dielectric loss. The shift in the imaginary modulus spectra towards high frequencies suggested a reduction in the dielectric relaxation time of the system.

Factors Influencing Preferential Anion Interactions during Solvation of Multivalent Cations in Ethereal Solvents

Most multivalent secondary batteries have employed electrolytes composed of cyclic ether solvents such as tetrahydrofuran or linear glycol ether solvents (glymes) such as 1,2-dimethoxyethane (G1). A robust understanding of multivalent cation solvation tendencies in these classes of solvents provides insight into corresponding structure–property relationships which, in turn, promotes the design and discovery of improved electrolytes. In this work, our goal is to systematically address how electrolyte constituent properties, namely, ether solvent structure and dication size, direct the solvation interactions of divalent electrolytes and their resultant properties. This study utilizes pulsed-field gradient (PFG) nuclear magnetic resonance (NMR) spectroscopy in conjunction with Raman spectroscopy and ionic conductivity measurements to elucidate the preferential interactions between multivalent cations, anions, and solvent molecules along with their correlated ion dynamics. These investigations incorporate two representative divalent cations (Ca2+ and Zn2+) as well as two ethereal solvent representatives from both the cyclic ether and glyme structural classes. The results reveal that anions coordinate more readily with divalent cations in cyclic ethers than in glymes. Furthermore, the coordination of the anions with Ca2+, i.e., contact-ion pair (CIP) formation is more pronounced than with Zn2+ in a glyme solvent of limited chain length (G1), providing insight into cation size effects that are important for translating solvation behavior across various multivalent electrolytes. Importantly, we find that specific anion coordination is more strongly controlled by solvent structure than by salt concentration in the practical range of 0.1–0.5 M. However, simply reducing these inner-sphere inter-ionic interactions by changing solvent structure does not necessarily de-correlate ionic motion. Instead, concentration-dependent changes in molar ionic conductivity suggest that second-shell interactions, i.e., solvent separated ion pairs (SSIPs), are prevalent in these electrolytes and that the solution dielectric constant, which is increased by the presence of dipolar ion pairs, is critical for controlling these interactions. These findings thus provide a basis for understanding the physical chemistry of multivalent battery electrolytes.

The effects of cycling on ionic and electronic conductivities of Li –ion battery electrodes

Li-ion battery performance is dependent on ionic and electronic transport, in turn dependent on electrode microstructure. Changes in microstructure during cell formation and cycling are poorly understood. In this work, the changes in effective ionic conductivity and diffusivity are quantified in terms of MacMullin number, a dimensionless ionic resistance that is related to tortuosity. Using an AC impedance technique, namely the blocking electrolyte method, the ionic resistance of electrode films at varying extents of cycling was determined. Variations in electronic resistivity were quantified by micro-scale measurements using a previously developed micro-four-line probe. Cycling effects on the ionic and electronic resistivity were investigated for a graphite anode and multiple cathode chemistries including LiCoO2 (LCO), LiNixCoyMnzO2 (NCM), and LiFePO4 (LFP). Clear evidence of changes in ionic and electronic resistivity were observed during cell formation and cycling. The magnitude of the changes depended on the chemistry of the electrodes and cycling conditions. The results indicate that, under normal cycling conditions, electronic resistivity increases while ionic resistivity is relatively stable and in some cases decreases, the latter being unexpected. However, under accelerated (high-temperature) cycling conditions, both electronic resistivity and ionic resistance were observed to increase.

Transport mechanisms of SARS-CoV-E viroporin in calcium solutions: Lipid-dependent Anomalous Mole Fraction Effect and regulation of pore conductance

The envelope protein E of the SARS-CoV coronavirus is an archetype of viroporin. It is a small hydrophobic protein displaying ion channel activity that has proven highly relevant in virus-host interaction and virulence. Ion transport through E channel was shown to alter Ca2+ homeostasis in the cell and trigger inflammation processes. Here, we study transport properties of the E viroporin in mixed solutions of potassium and calcium chloride that contain a fixed total concentration (mole fraction experiments). The channel is reconstituted in planar membranes of different lipid compositions, including a lipid mixture that mimics the endoplasmic reticulum-Golgi intermediate compartment (ERGIC) membrane where the virus localizes within the cell. We find that the E ion conductance changes non-monotonically with the total ionic concentration displaying an Anomalous Mole Fraction Effect (AMFE) only when charged lipids are present in the membrane. We also observe that E channel insertion in ERGIC-mimic membranes – including lipid with intrinsic negative curvature – enhances ion permeation at physiological concentrations of pure CaCl2 or KCl solutions, with a preferential transport of Ca2+ in mixed KCl-CaCl2 solutions. Altogether, our findings demonstrate that the presence of calcium modulates the transport properties of the E channel by interacting preferentially with charged lipids through different mechanisms including direct Coulombic interactions and possibly inducing changes in membrane morphology.

A significant enhancement of sodium ion conductivity in phosphate glasses by addition of WO3 and MoO3: the effect of mixed conventional-conditional glass-forming oxides.

Ion conducting oxide glasses are attractive materials for application in various electrochemical devices and an understanding of the structure-transport properties relationship is crucial for their development. An interesting effect of glass structure on the dynamics of mobile ions is the mixed glass-former effect which causes a non-linear change of ionic conductivity when glass-forming oxides get gradually substituted. Here, we report a strong, positive effect of structural changes on the conductivity of sodium ions in two glass systems 40Na2O-xMoO3-(60-x)P2O5 and 40Na2O-xWO3-(60-x)P2O5; x = 0-50 mol% where a conventional glass-forming oxide (P2O5) is gradually replaced by WO3/MoO3 which are conditional ones. In both glass systems, the compositional change in DC conductivity is non-linear, with the maximal increase of four orders of magnitude in the case of WO3 and three orders of magnitude in the case of MoO3. This significant enhancement of ionic conductivity is related to the formation of mixed phosphate-tungstate and phosphate-molybdate units in the glass network. The facilitating effect of these structural units on sodium ion dynamics is also observed in the changes of the shape of frequency-dependent conductivity and in the values of typical spatial extent of diffusion of sodium ions known as the Sidebottom length.

Polyester‐ZrO2 Nanocomposite Electrolytes with High Li Transference Numbers for Ambient Temperature All‐Solid‐State Lithium Batteries

AbstractPolyester‐ and polycarbonate‐based polymer electrolytes have attracted great interest after displaying promising functionality for solid‐state Li batteries. In this present work, poly(ϵ‐caprolactone‐co‐trimethylene carbonate) electrolytes are further developed by the inclusion of ZrO2 particles, prepared by an in situ sol‐gel method. SEM micrographs show that the ZrO2 particles are uniform and 30–50 nm in size. Contrary to many studies on filler‐polymer electrolytes, the changes in ionic conductivity are less significant upon addition of zirconia filler to the polymer electrolyte, but remain at ∼10−5 S cm−1 at room temperature. This can be explained by the amorphous nature of the polymer. Instead, high lithium transference numbers (0.83–0.87) were obtained. Plating/stripping tests with Li metal electrodes show long‐term cycling performance for >1000 cycles at 0.2 mA cm−2. Promising solid‐state lithium battery cycling results at ambient temperature using the material are also shown.

Neuronal Firing and Waveform Alterations through Ictal Recruitment in Humans.

Analyzing neuronal activity during human seizures is pivotal to understanding mechanisms of seizure onset and propagation. These analyses, however, invariably using extracellular recordings, are greatly hindered by various phenomena that are well established in animal studies: changes in local ionic concentration, changes in ionic conductance, and intense, hypersynchronous firing. The first two alter the action potential waveform, whereas the third increases the "noise"; all three factors confound attempts to detect and classify single neurons. To address these analytical difficulties, we developed a novel template-matching-based spike sorting method, which enabled identification of 1239 single neurons in 27 patients (13 female) with intractable focal epilepsy, that were tracked throughout multiple seizures. These new analyses showed continued neuronal firing with widespread intense activation and stereotyped action potential alterations in tissue that was invaded by the seizure: neurons displayed increased waveform duration (p < 0.001) and reduced amplitude (p < 0.001), consistent with prior animal studies. By contrast, neurons in "penumbral" regions (those receiving intense local synaptic drive from the seizure but without neuronal evidence of local seizure invasion) showed stable waveforms. All neurons returned to their preictal waveforms after seizure termination. We conclude that the distinction between "core" territories invaded by the seizure versus "penumbral" territories is evident at the level of single neurons. Furthermore, the increased waveform duration and decreased waveform amplitude are neuron-intrinsic hallmarks of seizure invasion that impede traditional spike sorting and could be used as defining characteristics of local recruitment.SIGNIFICANCE STATEMENT Animal studies consistently show marked changes in action potential waveform during epileptic discharges, but acquiring similar evidence in humans has proven difficult. Assessing neuronal involvement in ictal events is pivotal to understanding seizure dynamics and in defining clinical localization of epileptic pathology. Using a novel method to track neuronal firing, we analyzed microelectrode array recordings of spontaneously occurring human seizures, and here report two dichotomous activity patterns. In cortex that is recruited to the seizure, neuronal firing rates increase and waveforms become longer in duration and shorter in amplitude as the neurons are recruited to the seizure, while penumbral tissue shows stable action potentials, in keeping with the "dual territory" model of seizure dynamics.

Stretchable, Phase‐Transformable Ionogels with Reversible Ionic Conductor–Insulator Transition

AbstractStretchable iontronics with reversible conductor–insulator transitions are attracting great interest due to their promising applications in various fields of flexible electronics. However, effective conductivity switching of the ion conductors is still challenging. Here, a phase‐transformable ionogel (PTIG) that shows a reversible conductor–insulator transition with a very sharp change in bulk ionic conductivity (≈107 times) at a mild transition temperature of −15 °C is introduced. Moreover, this unique material shows good stretchability (840%), high transparency (97% transmittance in the visible range), and good stability. The ionogel material is used to prepare a long‐storage capacitor, which demonstrates good performance. Hence, the new PTIG has the potential for application in the development of flexible iontronics.

Campylobacter jejuni increases the paracellular permeability of broiler chickens in a dose-dependent manner

In recent years, several studies emphasize the deleterious effects of Campylobacter jejuni on the chicken intestine. In this context, it was shown that C. jejuni, contrary to the general belief, has a negative influence on the gut barrier in chickens. More precisely, we demonstrated that C. jejuni affects gut physiology characterized by changes in ion transport and transepithelial ion conductance, but the underlying mechanism is yet to be investigated. In the actual study, to determine epithelial paracellular permeability, the mucosal to serosal flux of 14C-mannitol in the small and large intestine was measured applying Ussing chamber. A total of seventy-five 1-day-old Ross 308 broiler chickens were housed in floor pens on wood shavings with feed and water provided ad libitum. Birds were randomly allocated to 3 different groups (n = 25 with 5 replicates/group) and infected at 14 d of age with a high (108 colony forming units [CFU]) or a low (104 CFU) dose of C. jejuni and a third group kept as noninfected control. Infection with the low dose of C. jejuni resulted in delayed cecal colonization but equalized at 21 d postinfection, independent of the dose. Invasion of liver and spleen with C. jejuni was only noticed in birds infected with 108 (CFU). Body weight (BW) and body weight gain of all birds infected with C. jejuni were lower than in the control group and varied with the dose of infection, confirming a negative correlation between the infection dose and birds BW. Mannitol flux in jejunum and cecum was significantly (P < 0.05) higher in all C. jejuni infected birds compared with control birds. Likewise, significant differences in mannitol flux of both jejunum and cecum were detected depending on the infection dose of C. jejuni. The correlation analyses revealed a positive relationship between Campylobacter dose and mannitol flux of both jejunum and cecum. Altogether, the actual results emphasize that the adverse effect of C. jejuni on gut permeability arises in a dose-dependent manner.

An affordable ammonia temperature-programmed desorption equipment and its calibration using the thermal decomposition of ammonium dihydrogen phosphate

A temperature-programmed desorption (TPD) equipment was built to follow ammonia release from solids; ammonia is detected following the ionic conductivity changes of saturated boric acid dissolution of with an ionic conductivity detector. The conductivity probe response is fast; it is insensitive to water, which is an advantage in the analysis of acid solids like zeolites and can be used with low heating rates or small samples. Ammonium dihydrogen phosphate (ADP) decomposition was used to calibrate the equipment and to check for its repeatability. In that process, it was found that the thermal decomposition of ADP was not well reported before. The decomposition of ADP follows a first-order kinetics and takes place in two steps; first, an ammonia molecule is released, and ammonia pyrophosphate is formed, then this decompounds to metaphosphoric acid and ammonia. Activation energies of 153 (4.6) kJ mol−1, and 69 (2.8) kJ mol−1, respectively, were calculated. NH3-TPD equipment requires a blank experiment due to the ability of the detector of sensing impurities in the carrier gas. Calibration of the technique gave a factor of conversion from conductivity to moles of ammonia of 347 (2.2) S m−1 mol−1 at 95.45% of confidence, a factor ten orders of magnitude higher than the limit of detection of the method calculated as 8.6 × 10-8 mole of ammonia. The limit of quantification was established as 2.9 × 10-7 mole of ammonia, a value quite low and useful when working with solid acids.

Gel polymer electrolyte based on PVDF-HFP:PMMA incorporated with propylene carbonate (PC) and diethyl carbonate (DEC) plasticizers : electrical, morphology, structural and electrochemical properties

To overcome the drawbacks of organic solvent−based liquid electrolytes and a solid polymer electrolyte as a separator in lithium polymer battery, in the recent study gel polymer electrolyte (GPE) using poly(vinylidene fluoride− hexafluropropylene) (PVDF−HFP) and poly (methyl methacrylate) (PMMA) as host polymers, lithium perchlorate (LiClO4) salt as conducting species and propylene carbonate (PC) and diethyl carbonate (DEC) plasticizers as an organic solvent has been prepared. The solution casting technique has been adopted to fabricate gel polymer electrolyte (GPE). The prepared GPE films were analyzed using different experimental techniques to discover the properties of GPE. The ionic conductivity of GPE films has been carried out using electrochemical impedance spectroscopic technique. The maximum ionic conductivity of 3.97E-4 S cm−1 has been obtained for GPE having 60 wt% PC:DEC. As an evidence of change in ionic conductivity, structural characterization has been analyzed using FTIR and SEM where, FTIR spectra reveal complex formation taking place between polymers, salt, and plasticizers and SEM micrograph shows a change in surface morphology with a change in plasticizers amount. Dielectric analysis has been also carried out in terms of dielectric constant () and dielectric loss (). Cyclic voltammetry (CV) has been applied to find electrochemical stability window.

ІОННІ КАНАЛИ В КОНТЕКСТІ ПОШУКУ МОЛЕКУЛЯРНИХ МІШЕНЕЙ РЕГУЛЯЦІЇ СКОРОТЛИВОСТІ МІОМЕТРІЮ

Many women now have complications in childbirth due to poor labor, which often threatens both mother and fetus. Also,the problem of prevention and treatment of premature uterine contractions is unresolved. Therefore, in this work we investigated the influence of ion channels as the end stage effectors of the regulatory cascades in the contractility of myometrium. To better understand the participation of TRPC4, TRPV4 and BKCa ion channels in myometrial contractility, we conducted experiments, keeping in mind the fact that changes in ionic conductivity of the plasma membrane regulate spontaneous and agonist-induced contractions. On the myometrial preparations of pregnant rats usingisolated tissue tensiometry, the amplitude of contractile force was recorded under the activation of these ion channels by their selective agonists. Obtained results allow us to consider (-) – englerin A as a way to stimulate uterine contractions in case of insufficient response to oxytocin, because at a concentration of 1 nM a significant increase in contraction force was developed and did not differ statistically from the response to oxytocin or carbacholin. The use of an agonist at concentrations of 30-100 nM causes some suppression of contractility. Based on the results describing the role of TRPV4 channels, namely the reduction of uterine smooth muscle contractions in response to their selective agonist GSK1016790A administration, we suggest that the main effect of activation of these channels depends on the expression and activity of adjacent calcium-dependent potassium channels. Our experiments found that the use of the liposomal form of quercetin to activate BKCa channels inhibits the excitability of myometrial cells more effectively than that dissolved in DMSO, which is promising for the correction of premature or excessive uterine activity.

Electrophysiological Biomarkers for Age-Related Changes in Human Atrial Cardiomyocytes: In Silico Study

Age-related changes in human cardiomyocytes are closely related to cardiac diseases, especially atrial fibrillation. Restricted availability of biological preparations from the human atrial myocardium complicates experimental studies on the aging processes in cardiomyocytes. In this preliminary study, we used available experimental data on the age-related changes in ionic conductances in canine atrial cardiomyocytes to predict possible consequences of similar remodeling in humans using two mathematical models (Courtemanche98 and Maleckar09) of human atrial cardiomyocytes. The study was performed using the model population approach, allowing one to assess variability in the cellular response to different interventions affecting model parameters. Here, this approach was used to evaluate the effects of age-related parameter modulation on action potential biomarkers in the two models. Simulation results show a significant decrease in the action potential duration and membrane potential at 20% of the action potential duration in aging. These model predictions are consistent with experimental data from mammalians. The action potential characteristics are shown to serve as notable biomarkers of age-related electrophysiological remodeling in human atrial cardiomyocytes. A comparison of the two models shows different behavior in the prediction of repolarization abnormalities.

Humidity Sensors Based on 3D Porous Polyelectrolytes via Breath Figure Method

AbstractA 3D porous P4VP film prepared via breath figure (BF) is used for quaternization to synthesize humidity‐sensitive polyelectrolytes. By combining the BF method, gaseous crosslinking, and screen‐printed electrodes, humidity sensors with good stability and a fast response to humidity change are obtained, thus making them possible for application in human breath monitoring. The water molecule adsorption of the porous polymer under different RHs is investigated using a quartz crystal microbalance. Cole–Cole plots and ionic conductivity change show that these devices function as humidity sensors under different humidity atmospheres.

Inducing interfacial progress based on a new sulfide-based composite electrolyte for all-solid-state lithium batteries

Li10GeP2S12-type sulfide solid electrolytes possess an obvious advantage in Li-ion conductivity, while show rather poor interfacial stability and compatibility against electrodes. Herein, the compositional tune via incorporating LiBr into Li10GeP2S12 matrix has been conducted to obtain a novel LiBr-Li10GeP2S12 composite electrolyte. It is interestingly found that high-conducting Li6PS5Br and Li10GeP2S12 co-exist, and Br substitution at the partial S sites of Li10GeP2S12 phase occurs in the composite electrolyte through the combination of Rietveld refinement against X-ray diffraction with Raman spectroscopy. In comparison with Li10GeP2S12 electrolyte itself, no appreciable change in ionic conductivity and activation barrier can be observed with respect to LiBr-Li10GeP2S12 composite electrolyte. While there is obvious improvement in interfacial conduction properties and chemical compatibility between cathode/anode and LiBr-Li10GeP2S12 electrolyte in terms of room-temperature interfacial resistances and temperature-dependence exchange current densities. Moreover, an all-solid-state cell containing the LiBr-Li10GeP2S12 composite electrolyte exhibits the distinct enhancement in discharge capacity and cycling stability during room-temperature galvanostatic cycling. In-situ electrochemical impedance spectroscopy measurements are discussed, suggesting that favorable interfacial modification of the cells can be provided in an internal way of the emergence of argyrodite Li6PS5Br in the new Li10GeP2S12-based electrolyte materials.

Utilizing a Tunable Triblock Copolymer for Design of Model Systems to Study Interactions at the Anion Exchange Polymer-Catalyst Interface

The heterogeneous microstructure of the electrode in polymer electrolyte-based electrochemical devices is not well understood. Due to its complex nature, it is challenging to investigate in a meaningful way. Model systems need to be designed to study controlled interfaces between polymer electrolytes and catalyst particles or surfaces. It is known from studies on proton exchange membranes that restructuring can occur at the polymer-catalyst interface and propagate into the bulk morphology of the material. This is potentially to the detriment of reactant and product species transport in the electrode, and ultimately affects device performance. There is currently little to no work reported on interactions between anion exchange polymers and non-precious metal catalysts more relevant to alkaline systems, such as silver or nickel. This research utilizes a highly tunable ABA triblock copolymer (polychloromethylstyrene-b-polycyclooctene-b-polychloromethylstyrene) to investigate different parameters within the chemistry space and how they influence interactions between the polymer and a catalyst surface. The synthesis route for the triblock copolymer has been optimized to achieve a variety of block lengths and A:B ratios, which ultimately lead to a range of characteristics (ionic conductivity, water uptake, mechanical properties) and morphologies when they are post-quaternized to produce AEMs. Additionally, the polycyclooctene (PCOE) midblock contains C=C double bonds that allow for a variety of post-modifications, such as radical crosslinking and hydrogenation. This system has given us a way to make changes to the chemistry and morphology of the polymer and investigate the effect on interactions at a silver surface. The polymer-catalyst interface has been fabricated for study in two different model systems – as a thin film on a flat surface of silver and in a constrained environment of silver nanoparticles. The structure and properties of the anion exchange polymer in these systems will be representative of any changes that occur due to interactions with the catalyst. In the thin film geometry, the properties of the polymer are studied by comparing the ‘bulk’ properties (represented as a thin film on atomically flat silicon where there are no interactions) with those of a thin film on a silver surface. Samples of varying thickness and chemistry have been prepared and the morphology of each system has been investigated using grazing incidence small angle and wide angle x-ray scattering (GISWAXS) and atomic force microscopy (AFM). Clear differences were found between the bulk properties and those at the silver interface that indicate a strong interaction between the anion exchange polymer and a silver catalyst surface. These change as a function of the various parameters under investigation, including A:B block ratios, molecular weight, chemistry of the polymer backbone, and chemistry of the quaternary ammonia cation group. For AEMs in silver nanoparticle constrained environments, properties under investigation are compared to those of the bulk polymer. Areas of current work include studying changes in thermal characteristics (using thermogravimetric analysis and differential scanning calorimetry), morphology (using transmission electron spectroscopy and small angle x-ray scattering), backbone crystallinity (using wide angle x-ray scattering), ionic and electrical conductivity, alkaline stability, vapor and liquid water uptake, and mechanical properties. Interactions between specific chemical groups are also being investigated with Fourier-transform infrared spectroscopy (FTIR). Furthering the understanding of interactions and morphological changes at the polymer-catalyst interfaces will provide a framework for rational design of anion exchange polymers. Ultimately, improvements in polymer design can have significant impacts on the transport of species in the electrode layer and overall device performance.

Semi‐Interpenetrating Network‐Structured Single‐Ion Conduction Polymer Electrolyte for Lithium‐Ion Batteries

AbstractA novel quasi solid single‐ion polymer electrolyte with semi‐interpenetrating network (semi‐IPN) structure has been prepared. The lithium‐ion conduction membrane is composed of both the cross‐linked lithiated poly‐2‐acrylamido‐2‐methylpropane sulfonic acid (PAMPS‐Li) as a polyanionic single‐ion lithium salt source and the high molecular weight polyethylene oxide (PEO) as a polymer matrix, in which the two components show great compatibility due to the special semi‐IPN structure. For such quasi‐solid electrolyte system, we have particularly studied the crystallinity variety and ionic conductivity change with a series of polymer salt concentration. The results show that the electrolyte has an appropriate mechanical stability, minimal crystallinity, and acceptable ionic conductivity of 1.34×10−5 S/cm at 60 °C. Furthermore, the lithium‐ion conduction membrane shows the lithium‐ion dominating conductive property and high transport number of 0.77. Moreover, the LiFePO4/Li batteries’ cycle results show a high discharge capacity of 140.0 mAh/g and a retention of 90.4 % after 100 cycles at the rate of 0.2 C.

Wearable Leather-Based Electronics for Respiration Monitoring.

This article presents a leather-based respiration sensor based on the ionic conductivity change of leather, caused by humidity variation during breathing. Leather was applied as a flexible substrate due to its biocompatibility, hydroscopicity, porosity, and ionic conductivity. Printing method was employed to fabricate the sensor, which could convert human respiration to electrical signals. By combining the leather with silver nanowires (AgNWs), data about human respiration rate, respiration depth, and respiration pattern can be acquired easily through a noninvasive way. Such sensor could work tens of hours consecutively due to the unique properties of leather.

Mechanistic Understanding of Cu-CHA Catalyst as Sensor for Direct NH3-SCR Monitoring: The Role of Cu Mobility.

The concept to utilize a catalyst directly as a sensor is fundamentally and technically attractive for a number of catalytic applications, in particular, for the catalytic abatement of automotive emission. Here, we explore the potential of microporous copper-exchanged chabazite (Cu-CHA, including Cu-SSZ-13 and Cu-SAPO-34) zeolite catalysts, which are used commercially in the selective catalytic reduction of automotive nitrogen oxide emission by NH3 (NH3-SCR), as impedance sensor elements to monitor directly the NH3-SCR process. The NH3-SCR sensing behavior of commercial Cu-SSZ-13 and Cu-SAPO-34 catalysts at typical reaction temperatures (i.e., 200 and 350 °C) was evaluated according to the change of ionic conductivity and was mechanistically investigated by complex impedance-based in situ modulus spectroscopy. Short-range (local) movement of Cu ions within the zeolite structure was found to determine largely the NH3-SCR sensing behavior of both catalysts. Formation of NH3-solvated, highly mobile CuI species showed a predominant influence on the ionic conductivity of both catalysts and, consequently, hindered NH3-SCR sensing at 200 °C. Density functional theory calculations over a model Cu-SAPO-34 system revealed that CuII reduction to CuI by coadsorbed NH3 and NO weakened significantly the coordination of the Cu site to the CHA framework, enabling high mobility of CuI species that influences substantially the NH3-SCR sensing. The in situ spectroscopic and theoretical investigations not only unveil the mechanisms of Cu-CHA catalyst as sensor elements for direct NH3-SCR monitoring but also allow us to get insights into the speciation of active Cu sites in NH3-SCR under different reaction conditions with varied temperatures and gas compositions.

Circadian Rhythms and Energy Metabolism Reprogramming in Parkinson's Disease.

Entropy rate is increased by several metabolic and thermodynamic abnormalities in neurodegenerative diseases (NDs). Changes in Gibbs energy, heat production, ionic conductance or intracellular acidity are irreversible processes impelling modifications of the entropy rate. The present review focuses on the thermodynamic implications in the reprogramming of cellular energy metabolism enabling in Parkinson's disease (PD) through the contrasting interplay of the molecular signaling pathways WNT/ β-catenin and PPARγ. In PD, WNT/β-catenin pathway is downregulated while PPARγ is upregulated. Thermodynamic behaviors of metabolic enzymes are modified by dysregulation of the canonical WNT/β-catenin pathway. Downregulation of WNT/β-catenin pathway leads to hypometabolism, oxidative stress and cell death through inactivation of glycolytic enzymes such as Glut, PKM2, PDK1, MCT-1, LDH-A but also to activation of PDH. In addition, in NDs, PPARγ is dysregulated even though it contributes to the regulation of several key circadian genes. PD processes may be considered as dissipative structures that exchange energy or matter with their environment far-from the thermodynamic equilibrium. Far-from-equilibrium thermodynamics are notions driven by circadian rhythms, which directly contribute to regulation of the molecular pathways WNT/β-catenin and PPARγ involved in the reprogramming of cellular energy metabolism enabling in Parkinson's disease.