Electric Conductivity

Besides its role in digestion and nutrient absorption, the crustacean gut participates in osmo/ionic regulation. We investigate microanatomy, ionic permeability and transepithelial electrophysiological parameters in the mid-and hindguts of three hyperosmoregulating crabs that inhabit estuarine waters (Chasmagnathus granulata), brackish mangrove swamp (Sesarma rectum) or freshwater (Dilocarcinus pagei). The abdominal hindguts are cuticle lined, the single-layered epithelia consisting of narrow, columnar cells exhibiting apically dense, unvesiculated cytoplasm. In the saltwater species, the thoracic midgut epithelium consists of tall, narrow, columnar cells displaying numerous, apical microvilli above dense apical cytoplasm. However, the corresponding gut segment in the hololimnetic species, D. pagei, consists of squat cells lacking apical microvilli, overlain by a heavy cuticle, constituting a thoracic or anterior hindgut. The midgut/ thoracic hindgut epithelia in all three crabs, and abdominal (posterior) hindgut of D. pagei, exhibit similar, small, lumen-negative voltages when perfused symmetrically with hemolymph-like salines. The hindguts of the saltwater species show similar, small, lumen-positive voltages. Small shortcircuit currents are detectable after voltage clamping. Washout and/or addition of luminal glucose or amino acids do not alter current or conductance, suggesting the absence of active, electrogenic nutrient absorption. Ion substitution did not disclose active, electrogenic absorption or secretion of Na 1 and/or Cl À . The midguts of the saltwater species exhibit similar conductances, greater than in D. pagei, but no ion selectivity; hindgut conductance is low, the epithelia showing moderate anion selectivity. The thoracic (anterior) and abdominal (posterior) hindgut epithelia of D. pagei, the freshwater species, exhibit similar, low conductances, and are ion selective. These findings reveal that active, electrogenic, salt and nutrient transport is undetectably low or absent. The reduced transepithelial conductances and notable ion selectivities in the abdominal and thoracic hindguts of D. pagei may reduce passive salt losses in fresh water, contributing to osmotic and ionic regulation.

Previous studies have shown that differing qualities of blood specimen seem to influence whole blood electrical aggregometry (WBEA), making it difficult to standardize the method. The aim of this study was to investigate the impact of hematocrit (HCT) and platelet count (PLC) on in vitro platelet aggregation in titrated whole blood (CWB) in order to compensate for their possible effects on impedance aggregometry. Red blood cells and blood platelets were isolated from fresh titrated whole blood taken from 15 healthy donors (mean age = 26 years) and recombined to 20 physiologically relevant combinations of hematocrit and platelet count (HCT: 20-50, PLC: 100-500). Platelet aggregability was measured using WBEA with three different triggers. A special-purpose software package was used in this study, ensuring proper calibration, acquisition, and evaluation of analogue to digital converted data, allowing the calculation of a set of characteristic parameters of each impedance curve. Most of the linear regressions showed that all parameters significantly depend on HCT and PLC. Furthermore, we found interactions of both variables, making it impossible to focus on the effects of one of the investigated variables only. The outcome of this study is a set of dependences, allowing the calculation of regressions for in vitro aggregation in whole blood, enabling a comparison of blood of any quality with each other, regardless of the variables HCT and PLC. Together with the previously defined dependence of sample age on WBEA data, this step should help to make this technique a more reliable and practicable clinical tool, making it suitable for daily routine investigations.

The reaction of ATP synthesis obeys the general thermodynamic relation between the rate constants for the forward and backward reactions: the ratio of these constants, i.e. the equilibrium constant depends only on the difference of the electrochemical potentials between two sides of the membrane ∆µ ~Н+, or proton motive force ∆µ ~Н+/F (pmf), and is independent of its individual components, the gradients of the electrical ∆ϕ = ϕ′ -ϕ′′ and chemical ∆µ Н + potentials (EP and CP). However, each of the two rates can differently depend on the pmf components, which manifests under non-equilibrium conditions created by the work of the proton pumps. The question of the actual form of this dependence is still debated: some authors believe that there is no such dependence [1, 2], and others suggest that there is a dependence upon pH [3]. Here we consider

Vibrio cholerae has been sporadically isolated from rivers in Tucumán, Argentina, since the outbreak in 1991. The aim of this study was to determine the environmental reservoir of the bacterium in these rivers, assessing the presence of Vibrio cholerae non-O1 and O1 (the latter both in its viable culturable and non culturable state) and its relationship to environmental physicochemical variables. 18 water samplings were collected in the Salí River (in Canal Norte and Banda) and the Lules River between 2003 and 2005. Physical-chemical measurements (pH, water temperature, electrical conductivity and dissolved oxygen) were examined. Vibrio cholerae was investigated with conventional culture methods and with Direct Immunofluorescence (DFA-VNC) in order to detect viable non culturable organisms. All isolated microorganisms corresponded to Vibrio cholerae non-O1 and non-O139 (Lules 26%, Canal Norte 33% and Banda 41%). The majority was found during spring and summer and correlated with tem...

Chemical composition and nutrient concentrations of 39 relatively poorly known Patagonian lakes (38-501S and from 701 to 681W) are described and analysed using principal component analysis (PCA). The general relationships between nutrients (total phosphorus, bioavailable phosphorus and dissolved inorganic nitrogen) and plankton biomass are examined. We seek to demonstrate that the extreme oligotrophy characterising many lakes and reservoirs of the Argentine Patagonian region of South America owes more to nitrogen deficiency than to a shortage of available phosphorus. The data show a range of trophic conditions with variable water chemistry characteristics. The first two axes of the PCA ordination explain most of the variance (63%). The first component of the variance in the environmental data is a trophic gradient, with positive correlations with the concentrations of nutrients (TP, SRP, DIN) and electrical conductivity and a negative correlation with transparency. For all the reservoirs considered, the calculated annual, summer and winter chlorophyll-a carrying capacities of the available phosphorus were consistently and significantly (Po0.05) in excess of observations but maximum chlorophyll-a values correlate with DIN availability. Indeed the chlorophyll-a carrying capacities, as an index of the resource-sustainable maximum biomass, of the available nitrogen gives a better predictive yield relationship than does P. Our findings are remarkable in so far as the general expectation that dinitrogen-fixing phytoplankton should thrive in the absence of dissolved inorganic nitrogen, at least to the supportive limits of the available phosphorus, is unfulfilled.

Membrane-less air-cathode microbial fuel cell (MFC), as one of the low-cost and potentially scalable modules in the bioelectrochemical technology, can treat wastewater and produce electricity without additional membrane and aeration cost. Nevertheless, the formation of biofilm (i.e., biofouling) on cathodes is observed to deteriorate the cathode performance. This study constructs an eight-unit membrane-less air-cathode MFC and aims to evaluate effects of cathodic biofouling on the performance of individual unit and the scale-up power efficiency during parallel connection. Results indicate cathodic biofoulings affect the cathodic performance by deteriorating both voltage and current output, further causing the performance variation among different cathodes. Moreover, the decrease of power densities by increasing the number of parallel-connected units is observed. Cyclic voltammetry demonstrates the onset potential decreases from 0.4 V to 0.1 V after cathodic biofouling. Electrochemical impedance spectroscopy reveals the polarization resistance of the biofouling cathode increases around two folds. In addition, we also find correlation between cathodic performance and microbial community and association between cathodic performance and unit position in the eight-unit MFC. Overall, our results suggest cathodic biofouling can be the key factor to limit the performance of parallel connection and warrant the need for further research to improve scale-up power efficiency.

This study examined the effect of H 2 O 2 on the TRPC6 channel and its underlying mechanisms using a TRPC6 heterologous expression system. In TRPC6-expressing HEK293T cells, H 2 O 2 significantly stimulated Ca 2؉ entry in a dose-dependent manner. Electrophysiological experiments showed that H 2 O 2 significantly increased TRPC6 channel open probability and whole-cell currents. H 2 O 2 also evoked a robust inward current in A7r5 vascular smooth muscle cells, which was nearly abolished by knockdown of TRPC6 using a small interfering RNA. Catalase substantially attenuated arginine vasopressin (AVP)-induced Ca 2؉ entry in cells co-transfected with TRPC6 and AVP V1 receptor. N-Ethylmaleimide and thimerosal were able to simulate the H 2 O 2 response. Dithiothreitol or glutathione-reduced ethyl ester significantly antagonized the response. Furthermore, both N-ethylmaleimide-and H 2 O 2 -induced TRPC6 activations were only observed in the cell-attached patches but not in the inside-out patches. Moreover, 1-oleoyl-2-acetyl-snglycerol effect on TRPC6 was significantly greater in the presence of H 2 O 2 . Biotinylation assays revealed a significant increase in cell surface TRPC6 in response to H 2 O 2 . Similarly, in cells transfected with TRPC6-EGFP, confocal microscopy showed a significant increase in fluorescence intensity in the region of the cell membrane and adjacent to the membrane. AVP also increased the fluorescence intensity on the surface of the cells co-transfected with TRPC6-EGFP and V1 receptor, and this response was inhibited by catalase. These data indicate that H 2 O 2 activates TRPC6 channels via modification of thiol groups of intracellular proteins. This cysteine oxidation-dependent pathway not only stimulates the TRPC6 channel by itself but also sensitizes the channels to diacylglycerol and promotes TRPC6 trafficking to the cell surface.

The initiation and propagation of electrochemical degradation in sodium-beta alumina type solid electrolytes has been found to involve grain boundaries. Degradation is preferentially initiated at 00.1 facets of large grains, lowering the critical current density threshold for coarse grained electrolytes. The critical current densities were determined by monitoring acoustic emissions during current flow. Direct indications of the implication of grain boundaries in degradation has been obtained from transmission and optical microscopy of degraded electrolytes • *on leave from the

Sodium-beta alumina solid electrolytes degrade during use in sodium sulfur cells. The degradation can take two forms: Mode I degradation involving the rapid propagation of macroscopic cracks driven by cathodic deposition of sodium in them; and Mode II degradation involving a slow degradation due to electron injection from the Na/..beta.. alumina contact. The initiation stage of Mode I is the most important one since cracks propagate rapidly once they are formed. The significance of the local microstructure on the Mode I initiation is discussed. It appears that grain boundaries can be favorable sites for Mode I failure initiation.

The effect of substrate nature on crystalline orientation and phase separation of P3HT and PCBM has been investigated. In particular a strongly hydrophilic substrate and a strongly hydrophobic one were employed. Hydrophobic substrate has been found to induce, at a given annealing temperature, a lower phase separation degree as well as a better packing of P3HT lamellae. We suggest these effects are caused from the different surface free energy between thin films and molecules which affect the ability of polymer to crystallize as well as migration of PCBM molecules away from the high surface free energy substrate (hydrophilic one). Since the discovery of photoinduced charge transfer between conjugated polymers and fullerene molecules [1] the interest in development of plastic solar cells as low-cost, light and flexible alternative to conventional silicon ones has strongly increased. Actually the most investigated couple is given by poly(3-hexylthiophene) (P3HT) and [6,6]-phenyl-C61-bu...

We examine time signals of ion current through single conically shaped nanopores in the presence of sub-millimolar concentrations of calcium ions. We show that calcium induces voltage-dependent ion current fluctuations in time in addition to the previously reported negative incremental resistance (Nano Lett. 2006, 6, 473-477). These current fluctuations occur on the millisecond time scale at voltages at which the effect of negative incremental resistance was observed. We explain the fluctuations as results of transient binding of calcium ions to carboxyl groups on the pore walls that cause transient changes in electric potential inside a conical nanopore. We support this explanation by recordings of ion current in the presence of manganese ions that bind to carboxyl groups 3 orders of magnitude more tightly than calcium ions. The system of a single conical nanopore with calcium ions is compared to a semiconductor device of a unijunction transistor in electronic circuits. A unijunction transistor also exhibits negative incremental resistance and current instabilities.

This study systematically investigates the effect of cathode porosity on the electrochemical and thermal behavior of high-rate lithium-ion batteries through a combination of experimental measurements and physics-based modeling. Four pouch batteries with cathode porosities of 21.0 %, 27.5 %, 34.0 %, and 40.5 % were fabricated by adjusting the calendaring pressure. A coupled electrochemical-thermal model was developed and validated, achieving high predictive accuracy with average relative errors ≤1.27 % for voltage and ≤9.2 % for temperature across 1C-30C discharge rates. Results show that reduced porosity improves discharge behavior at current rates lowering than 20C by mitigating polarization, while excessively low porosity at ultra-high rates (30C) aggravates lithium-ion concentration gradients, leading to a ''lithium-deficient dead zone" near the current collector and pronounced performance decline. Thermally, lower porosity slightly reduces temperature rise under moderate rates but increases it significantly at ultra-high rates due to elevated ohmic heating. Polarization heat decreases with porosity under moderate-low rates but reverses the trend at 30C, while reaction heat exhibits only minor changes, except for the emergence of an additional peak-valley pair during ultra-high-rate discharge. This study demonstrates that cathode porosity critically influences the balance between specific capacity, rate performance, and thermal behavior across various discharge rates. To achieve over 80 % capacity retention at 30C while maximizing energy density, an optimal porosity range of 27.5 %-34.5 % (compaction density: 3.1-3.4 g/cm 3) is recommended. These findings highlight the critical role of cathode porosity in shaping the electrochemical-thermal behavior of high-rate lithium-ion batteries and provide insights for the electrode structure optimization.

We report the thermoelectric performance of individual PbTe nanowires with sizes ranging from 76 to 436 nm grown from a vapor transport method that synthesizes high-quality, single-crystalline PbTe nanowires. Independent measurements of temperature-dependent Seebeck coefficient (S), thermal conductivity (κ) and electrical conductivity (σ ) of individual PbTe nanowires were investigated. By varying the nanowire size, the simultaneous increase and decrease of S (-130 μV K -1 ) and κ (1.2 W m -1 K -1 ), respectively, are achieved at room temperature. Our results demonstrate the enhanced thermoelectric properties of individual single-crystalline PbTe nanowires, compared to that of bulk PbTe, and can provide guidelines for future work on nanostructured thermoelectrics based on PbTe.

Department of Water, Land and Biodiversity Conservation and its employees do not warrant or make any representation regarding the use, or results of the use, of the information contained herein as regards to its correctness, accuracy, reliability, currency or otherwise. The Department of Water, Land and Biodiversity Conservation and its employees expressly disclaims all liability or responsibility to any person using the information or advice.

Several cervical spine braces and orthoses were evaluated for their compatibility with imaging in the MR scanner. Nine such devices were investigated: EXO cervical collar, Philadelphia collar, S.O.M.I. cervical orthosis, Guilford cervical orthosis, modified Guilford cervical orthosis, PMT halo cervical orthosis, modified PMT halo cervical orthosis, Bremer halo system, and Bremer MR-compatible halo system. Devices containing ferrous materials detected by a small bar magnet were not scanned. The remaining devices applied to a volunteer or a patient were scanned to evaluate image quality in the generation of images of the cervical spine and, in some cases, the brain. Orthoses that contained electrically conductive loops produced unsatisfactory scans. Replacement of ferrous materials with nonferrous metals and alloys and elimination of electrical loops proved to be necessary to make cervical braces and orthoses MR-compatible. Cervical orthoses with aluminum or graphite-carbon composite components that are interconnected with plastic joints such as the plastic ball-and-socket joints are, to date, the most successfully designed devices for MR compatibility. To make these orthoses CT compatible, low electron density materials are presently being evaluated to replace the titanium skull pins.

Several cervical spine braces and orthoses were evaluated for their compatibility with imaging in the MR scanner. Nine such devices were investigated: EXO cervical collar, Philadelphia collar, S.O.M.I. cervical orthosis, Guilford cervical orthosis, modified Guilford cervical orthosis, PMT halo cervical orthosis, modified PMT halo cervical orthosis, Bremer halo system, and Bremer MR-compatible halo system. Devices containing ferrous materials detected by a small bar magnet were not scanned. The remaining devices applied to a volunteer or a patient were scanned to evaluate image quality in the generation of images of the cervical spine and, in some cases, the brain. Orthoses that contained electrically conductive loops produced unsatisfactory scans. Replacement of ferrous materials with nonferrous metals and alloys and elimination of electrical loops proved to be necessary to make cervical braces and orthoses MR-compatible. Cervical orthoses with aluminum or graphite-carbon composite ...

PAN nanofibers can be easily converted into carbon nanofibers. Nanofibers are used in various applications due to their physical and chemical properties. Carbon nanofibers are made by carbonization process. Carbonization is done in an inert environment at high heat. However the heat required to carbonize the fibers usually destroy the fibers. To avoid this condition stabilization process is done. Stabilization is process of heating fibers in air. This process provides a ladder like structure to fiber. This process consumes considerable amount time and energy which add additional cost for making carbon nanofibers.

Surface acoustic wave (SAW) devices are currently used as passive remote-controlled sensors for measuring various physical quantities through a wireless link. Among the two main classes of designs—resonator and delay line—the former has the advantage of providing narrow-band spectrum informations and hence appears compatible with an interrogation strategy complying with Industry-Scientific-Medical regulations in radio-frequency (rf) bands centered around 434, 866, or 915 MHz. Delay-line based sensors require larger bandwidths as they consists of a few interdigitated electrodes excited by short rf pulses with large instantaneous energy and short response delays but is compatible with existing equipment such as ground penetrating radar (GPR). We here demonstrate the measurement of temperature using the two configurations, particularly for long term monitoring using sensors buried in soil. Although we have demonstrated long term stability and robustness of packaged resonators and signa...

Seawater intrusion into coastal river systems poses increasing challenges for freshwater availability and estuarine ecosystem integrity, especially under evolving climatic and anthropogenic pressures. This study presents a multidisciplinary investigation of marine intrusion dynamics within the Magra River estuary (Northwest Italy), integrating field monitoring, isotopic tracing (δ 18 O; δD), and multivariate statistical modeling. Over an 18month period, 11 fixed stations were monitored across six seasonal campaigns, yielding a comprehensive dataset of water electrical conductivity (EC) and stable isotope measurements from fresh water to salty water. EC and oxygen isotopic ratios displayed strong spatial and temporal coherence (R 2 = 0.99), confirming their combined effectiveness in identifying intrusion patterns. The mass-balance model based on δ 18 O revealed that marine water fractions exceeded 50% in the lower estuary for up to eight months annually, reaching as far as 8.5 km inland during dry periods. Complementary δD measurements provided additional insight into water origin and fractionation processes, revealing a slight excess relative to the local meteoric water line (LMWL), indicative of evaporative enrichment during anomalously warm periods. Multivariate regression models (PLS, Ridge, LASSO, and Elastic Net) identified river discharge as the primary limiting factor of intrusion, while wind intensity emerged as a key promoting variable, particularly when aligned with the valley axis. Tidal effects were marginal under standard conditions, except during anomalous events such as tidal surges. The results demonstrate that marine intrusion is governed by complex and interacting environmental drivers. Combined isotopic and machine learning approaches can offer high-resolution insights for environmental monitoring, early-warning systems, and adaptive resource management under climate-change scenarios.

We tested the effects of membrane phospholipids on the function of high-conductance, Ca2+-activated K+channels from the basolateral cell membrane of rabbit distal colon epithelium by reconstituting these channels into planar bilayers consisting of different 1:1 mixtures of phosphatidylethanolamine (PE), phosphatidylcholine (PC), phosphatidylserine (PS), and phosphatidylinositol (PI). At low ambient K+concentrations single-channel conductance is higher in PE/PS and PE/PI bilayers than in PE/PC bilayers. At high K+concentrations this difference in channel conductance is abolished. Introducing the negatively charged SDS into PE/PC bilayers increases channel conductance, whereas the positively charged dodecyltrimethylammonium has the opposite effect. All these findings are consistent with modulation of channel current by the charge of the lipid membrane surrounding the channel. But the K+that permeates the channel senses only a small fraction of the full membrane surface potential of th...

Water is an active participant of biochemical and physiological processes in living systems. This review explores the emerging recognition of water as structural biomarker, which gives knowledge about its biological environment studying water mobility by means of dielectric and nuclear magnetic resonance (NMR) techniques. Recent advances in the broadband dielectric spectroscopy (BDS) and NMR technique have deepened our understanding of water's behavior under confinement, hydration, and interactions with biomacromolecules and biological interfaces. These methods reveal pronounced deviations of water dynamic structure in biosystems from its bulk state, indicating manyfold specific interaction of water with its local environment. Microwave dielectric spectroscopy, particularly through analysis of γ-dispersion, captures disruptions in water hydrogen-bond network caused by interactions with ions, macromolecules, and cellular structures. Complementary NMR diffusion and relaxation studies enable precise characterization of water mobility and confinement effects. Evidence from biological tissues, cells, and model systems, including red blood cells, protein and polysaccharide hydrogels demonstrates how water's dielectric and NMR signatures can serve as indicators of biological systems stability and functionality. This review revisits a hypothesis proposed nearly 50 years ago, that water dynamical structure in biological systems is intimately connected with chemical composition and architecture of supramolecular and cellular structures in norm and pathology. Ultimately, dielectric and NMR assessments of water represent a powerful, yet underutilized, approach to non-invasive diagnostics and real-time biomonitoring. Recognizing water as a responsive probe of biological status opens new frontiers in the understanding of fundamental phenomena in living systems and their rational use in modern health and technological applications.

Electrical resistivity, Seebeck coefficient and Hall coefficient of pure thallium were measured at temperatures from 100 to 550 K, i.e. almost to the melting temperature of this metal. The history of the experiemental investigations of the transport properties of Tl is shortly reviewed. This is a first publication of the experimental data on the Seebeck coefficient and the Hall coefficient of Tl in such a broad temperature range.

The properties of amorphous carbon (a-C) deposited using a filtered cathodic vacuum arc as a function of the ion energy and substrate temperature are reported. The sp3 fraction was found to strongly depend on the ion energy, giving a highly sp3 bonded a-C denoted as tetrahedral amorphous carbon (ta-C) at ion energies around 100 eV. The optical band gap was found to follow similar trends to other diamondlike carbon films, varying almost linearly with sp2 fraction. The dependence of the electronic properties are discussed in terms of models of the electronic structure of a-C. The structure of ta-C was also strongly dependent on the deposition temperature, changing sharply to sp2 above a transition temperature, T1, of ≈200 °C. Furthermore, T1 was found to decrease with increasing ion energy. Most film properties, such as compressive stress and plasmon energy, were correlated to the sp3 fraction. However, the optical and electrical properties were found to undergo a more gradual transit...

We have monitored L-type Ca2+ channel activity, local cytoplasmic Ca2+ transients, the distribution of insulin- containing secretory granules and exocytosis in indi- vidual mouse pancreatic B-cells. Subsequent to the opening of the Ca2+ channels, exocytosis is initiated with a latency <100 ms. The entry of Ca2+ that precedes exocytosis is unevenly distributed over the cell and is concentrated to the region with the highest density of secretory granules. In this region, the cyto- plasmic Ca2+ concentration is 5-to 10-fold higher than in the remainder of the cell reaching concentrations of several micromolar. Single-channel recordings confirm that the L-type Ca2+ channels are clustered in the part of the cell containing the secretory granules. This arrangement, which is obviously reminiscent of the 'active zones' in nerve terminals, can be envisaged as being favourable to the B-cell as it ensures that the Ca2+ transient is maximal and restricted to the part of the cell where it is required to rapidly initiate exocytosis whilst at the same time minimizing the expenditure of metabolic energy to subsequently restore the resting Ca2+ concentration.

We have monitored L-type Ca2+ channel activity, local cytoplasmic Ca2+ transients, the distribution of insulin- containing secretory granules and exocytosis in indi- vidual mouse pancreatic B-cells. Subsequent to the opening of the Ca2+ channels, exocytosis is initiated with a latency <100 ms. The entry of Ca2+ that precedes exocytosis is unevenly distributed over the cell and is concentrated to the region with the highest density of secretory granules. In this region, the cyto- plasmic Ca2+ concentration is 5-to 10-fold higher than in the remainder of the cell reaching concentrations of several micromolar. Single-channel recordings confirm that the L-type Ca2+ channels are clustered in the part of the cell containing the secretory granules. This arrangement, which is obviously reminiscent of the 'active zones' in nerve terminals, can be envisaged as being favourable to the B-cell as it ensures that the Ca2+ transient is maximal and restricted to the part of the cell where it is required to rapidly initiate exocytosis whilst at the same time minimizing the expenditure of metabolic energy to subsequently restore the resting Ca2+ concentration.

Although N- and P-type Ca 2+ channels predominant in fast-secreting systems, Lc-type Ca 2+ channels (C-class) can play a similar role in certain secretory cells and synapses. For example, in retinal bipolar cells, Ca 2+ entry through the Lc channels triggers ultrafast exocytosis, and in pancreatic β-cells, evoked secretion is highly sensitive to Ca 2+ . These findings suggest that a rapidly release pool of vesicles colocalizes with the Ca 2+ channels to allow high Ca 2+ concentration and a tight coupling of the Lc channels at the release site. In binding studies, we show that the Lc channel is physically associated with synaptotagmin (p65) and the soluble N-ethylmaleimide-sensitive attachment proteins receptors: syntaxin and synaptosomal-associated protein of 25 kDa. Soluble N-ethylmaleimide-sensitive attachent proteins receptors coexpressed in Xenopus oocytes along with the Lc channel modify the kinetic properties of the channel. The modulatory action of syntaxin can be overcome by...

We consider a mathematical model which describes the frictional contact between a piezoelectric body and an electrically conductive foundation. The process is quasistatic, the material behavior is modeled with an electro-viscoelastic constitutive law and the contact is described with subdifferential boundary conditions. We derive the variational formulation of the problem which is in the form of a system involving two historydependent hemivariational inequalities in which the unknowns are the velocity and electric potential field. Then we prove the existence of a unique weak solution to the model. The proof is based on a recent result on history-dependent hemivariational inequalities obtained in Migórski et al. (submitted for publication) .

Human activities are source of many micropollutants to the environment: pesticides, pharmaceuticals, heavy metals, etc. that can enter the water cycle through stormwater or wastewater. Many of these substances are of major concern regarding their possible long-term impacts on both humans and the environment. In this study, we proposed to use substance flow analysis as tool for xenobiotics management in cities. We illustrated this approach with the case study of copper, cadmium and zinc in Lausanne, Switzerland. The results showed that around 1500 kg of copper, 9.3 kg of cadmium and 4000 kg of zinc enter the aquatic compartment yearly. These amounts contribute to sediment enrichment, which may pose a long-term risk for the aquatic organisms. The major sources of copper in receiving surface water are roofs and catenaries of trolleybuses, but the major source of cadmium and zinc are urban furniture. Substance flow analysis also highlights that these heavy metals enters surface water ma...

The fraction of the 110-K phase in the Bi-Sr-Ca-Cu-0 compound is rapidly increased if small amounts of Pb are incorporated in the compound. The maximum T, (R 0) of 106 K was ob- tained after a sintering treatment of several days at 860'C. Computer-generated powder diffraction patterns showed, when compared to the measured ones, the possibility for Pb to occupy Ca or Bi sites.

This study explores cold sintering of naturally occurring minerals as supplementary cementitious materials (SCM) or cement analogs, which have the potential to transform the traditional high-energy, high-emission cement manufacturing pathways. Diopside (MgCaSi 2 O 6), a natural inosilicate, is used as the model system. As diopside is hard for cold sintering directly (by itself), this study demonstrates that the addition of amorphous silica nanoparticles can enable cold sintering of diopside. The cold-sintered diopside-silica composites are characterized by X-ray diffraction, scanning electron microscopy, and transmission electron microscopy. The effect of the relative weight percentage of silica added is examined. The relative density of the cold-sintered composite reaches nearly 90% at 400 MPa and 200 • C in 60 min. For specimens with the addition of 30 wt% or more of amorphous SiO 2 , cold sintering also induces partial crystallization, converting a fraction of amorphous silica to quartz. The crystallization kinetics exhibits a stochastic nature. The Vickers hardness of the cold-sintered diopsidesilica composite increases with increasing amount of silica, whichpromotes cold sintering, reaching ∼3 GPa with 20 wt% or more silica. The diopside-silica composites studied here serve as a model system for metal-leached silicate mine tailings, which are expected to have nanoporous amorphous silica shells on silicate particles to enable the silica-assisted cold sintering mechanism discovered in this study.

Using time domain reflectometry (TDR), we studied stem water content (θstem), stem electrical conductivity (σstem), and their ratio for 220 d in stressed, installation‐cured, living trees of four species. Lysimeter‐grown mango (Mangifera indica L.), banana (Musa acuminata Colla), date (Phoenix dactylifera L.), and olive (Olea europaea L.) were subjected to several types of mild (intensity and duration) water stresses simulating horticultural orchard irrigation practices. This study of living trees was triggered by our previous study accomplished in uncured, thawed, native, cut stem segments. We have confirmed in living trees our earlier findings that θstem reacts sensitively and within minutes to water stress. This response is the main driver of σstem changes, by far exceeding the salinity effect on σstem Known irrigation rates, half‐hourly tree weights from load cells, and frequent sampling of drainage solution for volume and salinity independently confirmed our findings. Relative ...

Close, direct, and accurate monitoring of the plant water status may serve as a practical (irrigation scheduling) and a research (climate–environmental induced physiologic changes) tool. Methods for high‐frequency capacitance measurement (e.g., time domain reflectometry [TDR]) possess the potential for high resolution dielectric measurements with minimal dependence on properties of the measured matrix. The objective of this study is to test the accuracy, response time, and sensitivity of the TDR methodology in measuring changes in water status in a mango (Mangifera indica L., Cultivar ‘Kent’) tree stem exposed to several perturbations concerning water, salinity, fruit load, and radiation. Under several induced stress conditions, stem and root zone water content (θ) and electrical conductivity (σ) were simultaneously measured. Our study is distinct in its detailed and frequent measurements of stem water content (θstem) using short (29–70 mm) TDR probes in trees growing in a detached ...

concentrations of sulfate and chloride ions were recorded in the wells adjacent to the Sabzevaran fault. The highest concentrations of oxygen-18, tritium, and carbon-14 were observed in the central part of the fault. Also, groundwater in the fault zone exhibited distinct isotopic signatures compared to the eastern part of the aquifer. The difference in groundwater residence time and its recharge through the fault accounted for the isotopic difference. The results of this study indicated that the Sabzevaran fault caused the hydraulic disconnection of the western part of the aquifer of the Jiroft plain aquifer. This disconnection has affected both groundwater flow and quality. Due to the action of the fault, significant changes in surface topography, bedrock level, aquifer thickness, groundwater level, hydraulic gradient, groundwater flow direction, and water quality have occurred. Examining groundwater fluctuations, water quality parameters, and isotopic signatures also confirmed these findings. This study showed that the Sabzevaran fault acts as a hydraulic barrier to groundwater flow in the Jiroft plain and leads to the channelization of groundwater flow, especially in the western margin of the aquifer. To better understand the effect of the Sabzvararen fault on the groundwater system, further geoelectrical studies should be conducted at the fault zone. Monitoring groundwater depth, water quality, and the isotopic composition of wells adjacent to the fault zone is very important. It is suggested that the hydrogeological behaviour of the Sabzvararan fault be considered in the development of mathematical models of the groundwater system and the formulation of aquifer management strategies.

Introduction

Faults are among important geological structures, affecting groundwater flow and its quality. The faults’ function can cause the complexity of the groundwater flow in alluvial aquifers. Faults have different hydrogeological behaviors in geological environments. Fault zones can act as a conduit for groundwater flow, a barrier to groundwater flow, or a complex conduit/barrier system. The displacement of rock and sedimentary layers around the faults may lead to clear changes in the bedrock level, aquifer thickness, and groundwater depth. Faults can also channelize the groundwater flow and solute transport. Determining the hydrological behavior of fault structures can play an important role in the sustainable management of water resources. The Sabzevaran fault system is one of the most important fault systems in southern Iran. This system is a right-lateral transverse fault having a length of 150 km. Sabzevaran fault striking N-S (from the west of Jiroft city to the southwest of Kahnuj city in Kerman province, Iran) shows the evidence of Quaternary deformation. The fault scarps, cutoff ridges, and tilted rivers represent the activity of this fault. This study aims to investigate the hydrogeological behavior of the Sabzevaran fault and to evaluate its impact on the water fluctuations and groundwater quality.

Materials and Methods

Various data were used to investigate the hydrogeological behavior of the Sabzevaran fault. Geophysical surveys are one of the best indirect methods to study the subsurface geological situation. Geophysical studies were conducted by geoelectri method of Abkav- Louis Berger Company. The results were used to investigate the effect of the fault on changing the aquifer geometry and the situation of the subsurface layers. Investigating the groundwater level’ fluctuations is very important in water resources studies. The groundwater level’ fluctuations were investigated using the depth water data of the monitoring wells. The groundwater depth and isopotential maps were also plotted. Fault systems can affect the groundwater quality. To evaluate the impact of the Sabzevaran fault on the groundwater quality, 57 water samples were collected from abstraction wells and their parameters such as electrical conductivity and concentration of major cations (calcium, sodium, and magnesium) and anions (bicarbonate, sulfate, and chloride) were measured in the laboratory of Kerman Regional Water Authority. The isotopic ratio of the chemical elements of water molecules is a useful and new method in water resources studies. The isotopic contents of oxygen-18 (18O), tritium (3H) and carbon-14 (14C) were also used in this research.

Results and Discussion

The geoelectrical results confirmed the activity of the Sabzevaran fault and its role in changing the aquifer geometry. The Sabzevaran fault changed the bedrock topography, aquifer thickness and depth to water level. A significant difference in the depth of water can be observed around the Sabzevaran fault. There was a significant difference in the groundwater level due to fault action. The difference in water level on both sides of the fault ranged from 20m to more than 30m in different areas. The pattern of temporal fluctuations of groundwater was completely different on both sides of the fault. The groundwater level had a sinusoidal pattern on the west side of the fault, while the groundwater showed a completely downward trend in the east of the fault. The direction of groundwater flow was also different around the Sabzevaran fault. Groundwater flow was parallel to the fault line in the eastern part of the fault, while groundwater was channelized in the western part of the fault. The highest amount of electrical conductivity and concentrations of sulphate and chloride ions were recorded in the wells adjacent to the Sabzevaran fault. The highest concentrations of oxygen-18, tritum, and carbon-14 were observed in the middle part of the fault. Also, groundwater of the fault zone has a distinct isotopic content compared to the eastern part of the aquifer. The difference in groundwater residence time and its entrance into the aquifer through the fault were the reasons of the isotopic difference.

Conclusion

The results of this study indicated that the Sabzevaran fault caused the hydraulic disconnection of the western part of the aquifer of the Jiroft plain. This disconnectivity had affected the groundwater flow and its quality. Due to the action of the fault, clear changes in surface topography, bedrock level, aquifer thickness, groundwater level, hydraulic gradient, groundwater flow direction, and water quality had occurred. Examining the groundwater fluctuations, water quality parameters, and isotopic content of water samples also confirmed these findings. This study showed that the Sabzevaran fault behaves as a hydraulic barrier to groundwater flow in Jiroft plain and led to the channelization of the groundwater flow, especially in the western margin of the aquifer. In order to more accurately investigate the effect of the Sabzvararen fault on the groundwater system, it is necessary to carry out geoelectrical studies at the fault zone. Measuring groundwater depth, water quality and isotopic content of wells adjacent to the fault zone is very important. It is suggested to consider the hydrogeological behaviour of the Sabzvararan fault in the preparation of mathematical models of the groundwater system and the development of aquifer management strategies.

Management of groundwater resources in arid and semi-arid regions is particularly importantbecause the drinking water of a large part of the countries that are in arid and semi-arid areas relies on groundwater sources. The ever-increasing need for water due to severe socio-economic changes in the country and successive droughts in recent years has led to the expansion of deep and semi-deep wells and dams. Excessive extraction of groundwater by digging deep wells has caused a drop in the groundwater level. The groundwater level is one of the most important parameters affecting qanat discharge, preventing land subsidence, and ensuring permanent river recharge. Using new methods to know the changes in the groundwater level and simulating the effects of different management methods can be of great help in managing aquifer water resources. Recently, the use of different models and simulations of aquifers has helped researchers achieve better management goals, and groundwater modeling has become an important tool for managing aquifer water resources. Since Khorasan Razavi Province is located in the arid and semi-arid climatic zone, the exploitation of groundwater plays a significant role in providing part of the water needed for agriculture, drinking, and livestock farming. Thus, management of this valuable resource is essential. However, for effective management, a series of tools are required to predict and simulate the effects of various factors. One of these tools is modeling, which can yield acceptable results using some measurable parameters. Mashhad-Chenaran plain falls under the main basin of the Kashfroud River, which has an area of 990,914 ha and is located in northern Khorasan Razavi Province within the Qaraqom watershed. Mashhad-Chenaran plain includes a part of Mashhad City, Targaba-Shandiz, Chenaran, and a section of southern Quchan. The GMS model was used to investigate the effect of implementing the cultivation pattern and its effect on groundwater level changes in the northern part of the Mashhad-Chennaran aquifer. The required layers of the GMS model are: (a) observation well layer, (b) harvesting values layer, (c) aquifer recharge layer, (d) aquifer boundary layer, and (e) bottom rock layer of aquifer. In the simulation of the studied area, the cell size throughout the studied area was set at 300 × 300 m. According to the available data and information for running the model in a steady state, the initial hydraulic load was set to September 2006. Then, the LPF package was used in the MODFLOW model to solve the groundwater flow and level, and the groundwater flow of the studied area was simulated in both stable and unstable states. After preparing the coverage needed for the model, the model was calibrated in a steady-state. After calibrating the model in the steady state by introducing stress periods, the GMS model was calibrated in the unsteady-state. The results showed that the GMS model accurately simulated the water level after calibration. A review of the observed and simulated values chart shows that in some of the piezometers studied, the simulated groundwater level was higher than the observed one, and the model tended to overestimate the levels. To implement the management scenario, water used in all all agricultural wells was reduced by six percent, and the model was rerun. The results showed that the 6% reduction in water consumption in the agricultural sector led to an increase in the piezometers levels by approximately 5 to 15 cm on average, resulting in a groundwater level rise in the studied areas. One of the primary sources of water supply for agriculture, animal husbandry, and drinking in the Mashhad-Chenaran Plain region is groundwater. However, in recent years, due to excessive exploitation of groundwater resources and climate changes, t groundwater levels has declined, causing significant socio-economic impacts. Therefore, for better management and sustainable utilization of this groundwater source, it is necessary to monitor groundwater level fluctuations and predict the effects of various factors on these changes. One of the best tools for determining groundwater level fluctuations and assessing the impact of different factors is computer modeling. Groundwater models play crucial roles in managing these resources, and the MODFLOW model used in this research proved effective in simulating groundwater levels in both steady and unsteady conditions. Analysis of the observed and simulated balance using the GMS model demonstrated that a six percent reduction in agricultural water withdrawal could raise groundwater levels. However, this increase does not fully compensate for the damage caused by excessive withdrawal and only mitigates its effects.

Groundwater is the largest source of water in semi-arid regions. It is, therefore, essential to develop and exploit underground water resources to meet these needs. Precipitation is the main source of recharge for many aquifers. Changes in precipitation and groundwater level depth are closely related. It is more difficult to quantify groundwater availability and the long-term effects of climate change on groundwater than surface water. Although groundwater resources are more resilient than surface water, they are increasingly vulnerable to overexploitation, drought, pollution, and the lack of permanentconsistent precipitation, reducing quality and availability. The decrease in aquifer quality and storage capacity as a result of extraction exceeding the available surplus is due to the development of urban areas, the use of water-based industries, and an increased cultivation area, which jeopardizes underground water sources. Although human factors have a strong influence on groundwater, the natural hydrological cycle plays a key role in regulating the condition of the aquifer. In arid and semi-arid countries and regions of the world where surface water resources are relatively scarce, groundwater is often the most important or even the only source of water for regional food security, drinking water, economic development, and environmental conservation. Quantitative information about groundwater resources related to wells, springs, and qanats was provided by relevant organizations, including the Iranian Water Resources Research Organization (Tamab) and the Yazd Regional Water Organization, as well as previous research. For a more detailed investigation, the level and depth maps of underground water were drawn for five years based on the available information. The zoning map of fiveyear underground water changes was prepared using ArcGIS software to analyze the amount of water level drop in the observation wells. This research considered the distribution of wells, springs, and qanats and the trend of changes in their number, discharge, and annual consumption in different parts. There are 25, 122, 0, and 11 semideep wells, deep wells, springs, and qanats. It is worth mentioning that the statistics of the selected wells in each plain were used in the calculations and for the underground water maps, which have the most complete statistics during the selected period, so the number of wells mentioned in each plain is not necessarily the same as the number of wells in the piezometric network, and the length of the statistical period used did not necessarily cover the entire statistical period. The maximum depth of underground water in the Bahadoran and Shams aquifers in 2018 was 68 m and 47.7 m, respectively, with the deepest points in the northern areas of the Bahadoran aquifer and southern Shams aquifers, toward the southern areas of the Bahadoran aquifer and the eastern parts. The water depth in the west of the Shams aquifer has decreased; therefore, the minimum depth of underground water in both aquifers is approximately 11.8 m. The highest groundwater level in the aquifers of the Bahadoran area in 2018 was approximately 1538.91 m in the southwestern and western areas of the aquifers. In the eastern part of the Bahadoran aquifer, it reached 1447.3 m, and in the southern part of the Shams aquifer, it reached 1190 m in 2018. The groundwater level in 2013 and 2008 was higher than in 2018, but it did not change significantly. The decline in groundwater level from 2008 to 2013 and from 2013 to 2018 was approximately 13.14 m and 6.68 m, respectively. Examining the changes in the groundwater level during the statistical period shows that the overall trend has been downward. This study investigated the level and depth of underground water sources in the Bahadoran watershed in Yazd province. The results indicate an alarming drop in the groundwater table. The spatial distribution of groundwater extraction differed throughout the watershed, so some areas experienced a severe decrease in the water level. In addition, due to the use of these resources, the seasonal variation in water level reduction differs. In the absence of surface water sources due to a decrease in precipitation and prolonged droughts, the majority of groundwater extractıon is done for various purposes, such as increasing the area of agricultural cultivation. This excessive extraction occurs through additional water wells. Therefore, it is necessary to carry out comprehensive studies to investigate the relationship between the extent of vegetation in the area and the amount of groundwater extractıon from aquifers using satellite images. In addition, it is suggested to evaluate the balance between groundwater extractıon and recharge in all watersheds of the country. The results of this study provide policy makers and managers with information on changes in groundwater resources in aquifers, which can be used for optimal management .

Graphene nanoplatelet (GnP)-filled polysulfone (PSU) cellular nanocomposites, prepared by two different methods—namely, water vapor-induced phase separation (WVIPS) and supercritical CO2 dissolution (scCO2) foaming—were produced with a range of densities from 0.4 to 0.6 g/cm3 and characterized in terms of their structure and electrical conduction behavior. The GnP content was varied from 0 to 10 wt%. The electrical conductivity values were increased with the amount of GnP for the three different studied foam series. The highest values were found for the microcellular nanocomposites prepared by the WVIPS method, reaching as high as 8.17 × 10−2 S/m for 10 wt% GnP. The variation trend of the electrical conductivity for each series was analyzed by applying both the percolation and the tunneling models. Comparatively, the tunneling model showed a better fitting in the prediction of the electrical conductivity. The preparation technique of the cellular nanocomposite affected the resultant...

Polyetherimide (PEI) foams with graphene nanoplatelets (GnP) were prepared by supercritical carbon dioxide (scCO2) dissolution. Foam precursors were prepared by melt-mixing PEI with variable amounts of ultrasonicated GnP (0.1–2.0 wt %) and foamed by one-step scCO2 foaming. While the addition of GnP did not significantly modify the cellular structure of the foams, melt-mixing and foaming induced a better dispersion of GnP throughout the foams. There were minor changes in the degradation behaviour of the foams with adding GnP. Although the residue resulting from burning increased with augmenting the amount of GnP, foams showed a slight acceleration in their primary stages of degradation with increasing GnP content. A clear increasing trend was observed for the normalized storage modulus of the foams with incrementing density. The electrical conductivity of the foams significantly improved by approximately six orders of magnitude with only adding 1.5 wt % of GnP, related to an improved...

Thermal stability, electrical conductivity and ammonia sensing studies on p-toluenesulfonic acid doped polyaniline:titanium dioxide (pTSA/Pani:TiO 2 ) nanocomposites, Sensors and Actuators B 157 (2011) 122-129. 2. Mohd Omaish Ansari and Faiz Mohammad; Thermal stability of HCl-dopedpolyaniline and TiO 2 nanoparticles based nanocomposites. Journal of Applied Polymer Science (2011).

In the high-latitude regions of Saturn, the ionosphere is strongly coupled to the magnetosphere through the exchange of energy. The influx of energetic particles from Saturn's magnetosphere enhances the ionospheric densities and temperatures, affects the electrodynamical properties of the ionosphere, and contributes to the heating of the thermosphere. It is therefore critical to accurately model the energy deposition of these magnetospheric particles in the upper atmosphere in order to evaluate key ionospheric quantities of the coupled magnetosphere-ionosphere system. We present comprehensive results of ionospheric calculations in the auroral regions of Saturn using our Saturn Thermosphere-Ionosphere Model (STIM). We focus on solar minimum conditions during equinox. The atmospheric conditions are derived from the STIM 3-D General Circulation Model. The ionospheric component is self-consistently coupled to the solar and auroral energy deposition component. The precipitating electrons are assumed to have a Maxwellian distribution in energy with a mean energy E m and an energy flux Q 0 . In the presence of hard electron precipitation (1 < E m ≤ 20 keV) with Q 0 > 0.04 mW m -2 , the ionospheric conductances are found to be proportional to the square root of the energy flux, but the response of the ionosphere is not instantaneous and a time delay needs to be applied to Q 0 when estimating the conductances. In the presence of soft electron precipitation (E m < 500 eV) with Q 0 ≤ 0.2 mW m -2 , the ionospheric conductances at noon are found to be primarily driven by the Sun. However, soft auroral electrons are efficient at increasing the ionospheric total electron content and at heating the thermal electron population.

The only way to get a global, instantaneous picture of the energetic particle input over the auroral oval is through spectral imaging. The major driver of auroral emissions in the high-latitude ionosphere is overall electron precipitation. However, for certain locations and times, such as the equatorial edge of the evening auroral oval, proton precipitation can be the major energy source and thus the primary contributor to auroral emissions. Using kinetic transport models to describe the transport of energetic particles in the atmosphere, we analyze UV spectra from the STP78-1 satellite mission during magnetically disturbed conditions (Kp = 6) in the evening sector of the auroral oval. We discuss the contribution of protons and electrons to the auroral emissions. The energy flux of the incident protons is inferred from the H Lyman a emissions, after removing the H geocoronal background induced by solar radiation. Both the mean energy and energy flux of electron precipitation are inferred from non-H emissions (N II 108.5 nm, N 2 135.4 nm, and O I 135.6 nm), after removing the contribution of proton precipitation. From the latitudinal distribution of the incident energy flux the location of the electron and proton aurorae is discussed. The estimation of the particle characteristics allows one to infer the Pedersen and Hall electrical conductances induced by particle precipitation. For the studied substorm period, energetic protons contribute significantly to the Pedersen conductance, $25-30% overall of the total particle-induced conductances and much more at the equatorward edge of the midnight aurora. Because protons and electrons do not interact in the same way with the atmosphere, our study shows that while analyzing auroral spectra and studying the state of the ionosphere, it is crucial to separate electron and proton components of the precipitation. The method described to disentangle the relative contribution of precipitating electrons and protons may be applicable to the UV data of the upcoming TIMED and DMSP missions.

O efeito do posicionamento de amostragem para a quantificação do N-NO 3 residual no solo foi determinado após o cultivo do tomateiro fertirrigado. Três experimentos foram conduzidos, em ambiente protegido, com fertirrigação por gotejamento. Em cada experimento, os tratamentos foram arranjados em parcela subdivida, com dez critérios para o manejo da adubação nitrogenada na parcela e posições de amostragem do solo na subparcela. Esses foram arranjados no delineamento experimental de blocos ao acaso. Foi determinado o teor de N-NO 3 no solo de amostras retiradas no final do ciclo de cada experimento, em diferentes posições. Em todos os experimentos, o teor de N-NO 3 residual no solo foi proporcional à quantidade de N aplicada nos diferentes critérios. Em condições de ambiente protegido e fertilizante nitrogenado fertirrigado por gotejamento, a melhor estratégia de amostragem do solo para a determinação do teor de N-NO 3 residual foi obtida pela utilização de amostra composta tomada em posições distanciadas em 10 cm da planta na entre linha e sobre a linha de transplante.

The effect of sample positioning for quantification of residual N-NO 3 in soil was determined after cultivating fertirrigated tomato plants. Three experiments were carried out in an unheated greenhouse, using drip fertirrigation. Soil N-NO 3 level was determined from samples taken at the end of the cycle of each experiment. In all the experiments, the residual N-NO 3 level of the soil was proportional to the amount of N applied in different criteria. Under unheated greenhouse conditions and using nitrogen fertilization by drip fertirrigation, the best soil sampling strategy for residual N-NO 3 level determination was obtained by the use of a composite sample taken at a position 10 cm from the plants, between rows, and on the transplant row.