Increase In Ion Concentration Research Articles

Mechanism, Kinetics, and Potential of Mean Force of Evaporation of Water from Aqueous Sodium Chloride Solutions of Varying Concentrations.

The mechanism, kinetics, and potential of mean force of evaporation of water from aqueous NaCl solutions are investigated through both unbiased molecular dynamics simulations and also biased simulations using the umbrella sampling method. The results are obtained for aqueous solutions of three different NaCl concentrations ranging from 0.6 to 6.0 m and also for pure water. The rate of evaporation is found to decrease in the presence of ions. It is found that the process of evaporation of a surface water molecule from ionic solutions can be triggered through its collision with another water or chloride ion. Such collisions provide the additional kinetic energy that is required for evaporation. However, when the collision takes place with a Cl- ion, the evaporation of the escaping water also involves a collision with water in the vicinity of the ion at the same time along with the ion-water collision. These two collisions together provide the required kinetic energy for escape of the evaporating water molecule. Thus, the mechanism of evaporation process of ionic solutions can be more complex than that of pure water. The potential of mean force (PMF) of evaporation is found to be positive and it increases with increasing ion concentration. Also, no barrier in the PMF is found to be present for the condensation of water from vapor phase to the surfaces of the solutions. A detailed analysis of the unsuccessful evaporation attempts by surface water molecules is also made in the current study.

Formation of Composite Coatings of Layered Double Hydroxide Particles and Hydroxide Gel by Electrophoretic Deposition on Mg Alloy and Corrosion Resistance

To improve the corrosion resistance of Mg alloys, composite coatings of layered double hydroxide intercalated with carbonate (LDH-CO3, hydrotalcite) particles and magnesium and aluminum hydroxide gel were formed on AZ31 Mg alloy by electrophoretic deposition (EPD) using the LDH-CO3 suspension with Mg(NO3)2 and Al(NO3)3 in total of 1.25–125 mmol/L. Wet-dry cyclic corrosion tests were performed for the coated specimens after ultrasonication. LDH-CO3 particle-rich layer and magnesium and aluminum hydroxide gel-rich layer almost alternately piled up to form a composite layer. The hydroxide gel adhered the particles together and to the substrate. At the bottom of the composite layer, flake-shape LDH-structured substance densely covered the substrate surface. The coverage and thickness of the composite layer increased from sub-micrometers to 30 µm with an increase of Mg and Al ion concentrations of the suspension. By ultrasonication, parts of the composite layer delaminated to expose the LDH-structured substance layer, while the coverage by the remaining composite layer increased with an increase of Mg and Al ion concentrations. The LDH-CO3 particles and hydroxide gel composite coatings prevented corrosion initiation even in the areas where the LDH-structured substance layer was exposed.

Comparative Spectrophotometric Determination of Neodymium (III), Praseodymium (III), Samarium (III) and Terbium (III) in Aqueous and Micelle Media

This research work titled comparative spectrophotometric determination of neodymium (III), praseodymium (III), samarium (III) and terbium (III)in aqueous and micelle media using schiff base was carried out with the aim to use a simple, rapid and sensitive spectrophotometric method for the determination of Nd (III), Pr (III), Sm(III) and Tb(III) using the Schiff base 2,2′-((1E,1′E)-(1,2-phenylenebis(azanlylidene)bis (methanylylidene))diphenol (BSOPD) as a ligand. Spectral and absorbance measurements were carried out using UV/Visible Spectrophotometer (Jenway model no.: 6305) with 1-cm matched quartz cells. This method of experiment was based on the formation of green coloured complexes, upon the reaction of Nd(III) and Pr(III) and a brown coloured complexes for Sm(III) and Tb(III) having a maximum absorbance of 376, 386, 384 and 380 nm respectively. The comparative analysis of the complexes formed in aqueous and in micellar media were investigated in this study. In the obtained results, it was discovered that, Beer’s law was obeyed in the concentration ranges of 0.001 - 0.02 ppm. The molar absorptivity was found to be in the range of 7,776- 23,197 and 27,087 dm³mol^-1cm^-1 and the Sandell’s sensitivity for the compounds analyzed were in the ranges of 6.13-19.34 g cm^-2. The increase in absorbance in the presence of the surfactants is due to micelle formation. The reactants were bound in a small volume of stern layer of the micelle leading to a greater increase in concentration effect. This effect in concentration reaches a maximum before decreasing due to dilution effect occasioned by increase in metal ion concentration.

An increase in the cytosolic concentration of free calcium ions activates the neutrophil NADPH-oxidase provided that the free fatty acid receptor 2 has been allosterically modulated

Signals generated by free fatty acid receptor 2 (FFA2R) can activate the neutrophil NADPH-oxidase without involvement of any orthosteric FFA2R agonist. The initiating signals may be generated by P2Y2R, the receptor for ATP. An FFA2R specific allosteric modulator (PAM; Cmp58) was required for this response and used to investigate the mechanism by which signals generated by ATP/P2Y2R activate an FFA2R dependent process. The P2Y2R induced signal that together with the modulated FFA2R activates neutrophils, was generated downstream of the Gαq containing G protein coupled to P2Y2R. A rise in the cytosolic concentration of ionized calcium ([Ca2+]i) was hypothesized to be the important signal. The hypothesis gained support from the finding that the modulator transferred the neutrophils to a Ca2+sensitive state. The rise in [Ca2+]i induced by the Ca2+ specific ionophore ionomycin, activated the neutrophils provided that an allosteric modulator was bound to FFA2R. The activity of the superoxide generating NADPH-oxidase induced by ionomycin was rapidly terminated and the FFA2Rs could then no longer be activated by the FFA2R agonist propionate or by the signal generated by ATP/P2Y2R. The non-responding state of FFA2R was, however, revoked by a cross-activating allosteric FFA2R modulator. The [Ca2+]i mediated activation of neutrophils with their FFA2Rs allosterically modulated, represent a unique regulatory receptor crosstalk mechanism by which the activation potency of a G protein coupled receptor is controlled by a receptor-crosstalk signaling system operating from the cytosolic side of the plasma membrane.

Crystallographic and luminescence studies of Gd2Si2O7: Er3+ nanomaterials for NUV energized lighting applications

Gd2-xSi2O7:xEr3+ (x = 1–6 mol%) green light-emitting nanomaterials were prepared via Solution-combustion (SC) synthetic route. Structural and spectrophotometric analysis were executed to recognize the phase identification and luminescence characteristics of the designated nanophosphors, respectively. The obtained crystallographic parameters clearly indicated that the synthesized nanomaterials are structured into the triclinic phase with P-1 space group. The enlarged view of concentration dependent XRD patterns of Gd2Si2O7:Er3+ samples specifies that as the Er3+ ion concentration increases, the diffraction peaks show a regular shift towards higher value of 2 theta. The average particle size lies in range of several nanometres which distinctively rationalizes the requirements of these samples in lighting applications. Under NUV excitation at 389 nm, Gd2Si2O7:Er3+ samples exhibit cool green light emission corresponding to 4S3/2→4I15/2 (553 nm) electronic transitions of dopant ion. The dipolar-dipolar interaction is plausible for the energy transference amongst the dopants in Gd2Si2O7:Er3+ materials. The triple-exponential fitting behavior explains the possibility of occurrence of three different cationic sites for the Er3+ ions in the host matrix.

IPLA2 inhibition blocks LysoPC-induced TRPC6 externalization and promotes Re-endothelialization of carotid injuries in hypercholesterolemic mice

Lipid oxidation products, including lysophosphatidylcholine (lysoPC), accumulate at the site of arterial injury after vascular interventions and hinder re-endothelization. LysoPC activates calcium-permeable channels, specifically canonical transient receptor potential 6 (TRPC6) channels that induce a sustained increase in intracellular calcium ion concentration [Ca2+]i and contribute to dysregulation of the endothelial cell (EC) cytoskeleton. Activation of TRPC6 leads to inhibition of EC migration in vitro and delayed re-endothelization of arterial injuries in vivo. Previously, we demonstrated the role of phospholipase A2 (PLA2), specifically calcium-independent PLA2 (iPLA2), in lysoPC-induced TRPC6 externalization and inhibition of EC migration in vitro. The ability of FKGK11, an iPLA2-specific pharmacological inhibitor, to block TRPC6 externalization and preserve EC migration was assessed in vitro and in a mouse model of carotid injury. Our data suggest that FKGK11 prevents lysoPC-induced PLA2 activity, blocks TRPC6 externalization, attenuates calcium influx, and partially preserves EC migration in vitro. Furthermore, FKGK11 promotes re-endothelization of an electrocautery carotid injury in hypercholesterolemic mice. FKGK11 has similar arterial healing effects in male and female mice on a high-fat diet. This study suggests that iPLA2 is a potential therapeutic target to attenuate calcium influx through TRPC6 channels and promote EC healing in cardiovascular patients undergoing angioplasty.

Peptide Sodium Channels Modulator Mu-Agatoxin-Aa1a Prevents Ischemia-Reperfusion Injury of Cells

Ischemia-reperfusion injury (IRI) is an irreversible functional and structural injury. Restoration of normal oxygen concentration exacerbates the emergence and development of deadly cells. One of the possible moments of reperfusion damage to cells is an increase in the intracellular concentration of sodium ions. In this article, we study the mu-agatoxin-Aa1a, a modulator of sodium channels, on the processes of IRI cells damage. The toxin was synthesized using an automatic peptide synthesizer. Hypoxia was induced by reducing the content of serum and oxygen in the CHO-K1 culture. The influence of the toxin on the level of apoptosis; intracellular concentration of sodium, calcium, and potassium ions; intracellular pH; totality of reactive oxygen species (ROS), nitric oxide (NO), and ATP; and changes in the mitochondrial potential were studied. The experiments performed show that mu-agatoxin-Aa1a effectively prevents IRI of cells. Toxin reduces the level of apoptosis and prevents a decrease in the intracellular concentration of sodium and calcium ions during IRI. Mu-agatoxin-Aa1a contributes to the maintenance of elevated intracellular pH, reduces the intracellular concentration of ROS, and prevents the decrease in intracellular NO concentration and mitochondrial potential under conditions of reoxygenation/reperfusion. An analysis of experimental data shows that the mu-agatoxin-Aa1a peptide has adaptogenic properties. In the future, this peptide can be used to prevent ischemia/reperfusion tissue damage different genesis.

Salinity, temperature and pressure effect on hydrogen wettability of carbonate rocks

Hydrogen had been injected into the geologic formations, and the geologic formation wettability would influence the hydrogen storage. Hydrogen wettability of sandstone reservoirs (quartz), mica and other rocks have been explored in the previous study. However, the research on hydrogen wettability of carbonate rocks was lacked. In this study, we studied the carbonate rock wettability alteration when exposed to the hydrogen environments. Salinity, temperature and pressure effect on H 2 /carbonate rock/brine wettability were explored. When the solutions ions concentration increased, the advancing/receding contact angle would increase, and divalent ions could make the contact angle higher than monovalent ion, which was because ions could compress the electric double layer. The carbonate rock powder in brine showed negative charge, and the zeta potential increased with higher ions concentration. When temperature increased and the pressure decreased, the contact angle would decrease, which was related to the H 2 gas density and molecular interactions. • The divalent ions showed higher effect on the hydrogen wettability alteration than monovalent ion. • The contact angle increased with the increase of ions concentration. • The contact angle increased with the decrease of temperature. • The contact angle increased with the increase of pressure. • The high salinity could compress the electric double layer, and increased the contact angle.

Variation of ZnS deposition time on chemically prepared Cd1-xZnxS ternary compound from CdS/ZnS bilayers

Chemical bath deposition (CBD) was successfully used for the preparation of cadmium zinc sulphide (Cd1-xZnxS) ternary alloy thin film with × composition, in the range of 0 and 1, from post annealing treatment of bilayer cadmium sulphide (CdS)/zinc sulphide (ZnS) thin film. Increasing the ZnS layer deposition time leads to an increase in the overall thickness of the bilayer with an attendant increase in zinc ion concentration. From the XRD measurement, thin film samples presented hexagonal structure, with a shift in the peaks position to higher angles coupled with a decreasing crystalline size and lattice constants as zinc ion is continuously incorporated into the Cd1−xZnxS thin films. The continuous addition of the wider band gap energy ZnS into the ternary compound as the ZnS deposition time increases constantly brought about the widening of the band gap energy. Energy dispersive spectroscopy (EDS) measurement established the presence of the major elements Cd, Zn and S. The room temperature electrical resistivity determined from the point probe measurement ranges between 2.1 × 10-3 and 1.2 × 101 Ωm, and showed a decrease with increasing zinc ion contents. In this study, it was established that Cd1-xZnxS ternary compounds can be prepared starting with CdS/ZnS bilayer, and its post thermal annealing, with the band gap energy able to be accurately controlled by modifying the CdS/ZnS thickness ratio through variation of ZnS deposition time. The results from CdZnS thin film compounds prepared under this present condition established its superior effectiveness as a buffer layer in thin film solar cells.

Techno-Economic Analysis of Vacuum Membrane Distillation for Seawater Desalination

Seawater desalination is an affordable and viable solution to the growing freshwater scarcity problem in water scarce regions. The current study focuses on cost analysis of Vacuum Membrane Distillation (VMD) setup for removing salts from water. The membrane used in the flat sheet VMD module was Polytetrafluoroethylene (PTFE) with 250 mm × 200 mm dimensions and 165 µm thickness. The experiments were carried out with variations in parameters such as velocity, pressure, concentration, and temperature. For the cost analysis, the operational, maintenance, instrumentation, and capital cost of the lab model was considered and then upscaled. A range of experiments was performed for NaCl and KCl under variations of operating parameters. It was noted that, for the NaCl solution, the increase in temperature from 50 °C to 70 °C doubled the permeate flux. However, for the conditions tested, the concentration shift from 0.25 M to 0.75 M decreased the permeate flux by 1.4% because the increase in ion concentrations along the membrane lowers the vapor pressure, restricting the permeate flux. The results trend for the KCl solution was similar to the NaCl; at temperature T1, it was noted that increased concentration from 0.25 M to 0.75 M significantly reduces the permeate flow. The reduction in permeate flow was nonlinear for a given pressure 30 kPa and velocity 5.22 m/s, but linear for all other variables. It was also observed that with an increase in temperature from 60 °C to 70 °C, the permeate flux for concentration 0.25 M was 49% for all the combinations of pressure and velocity. In addition, permeate flow increased 53% from temperature 50 °C to 60 °C and 49% from temperature 60 °C to 70 °C for both the solutions at a concentration of 0.25 M. This shows that the temperature also had a profound impact on the permeate flux. The economic analysis and market survey shows that the cost of clean water at the lab level was high which can be significantly reduced using a large-scale setup providing 1,000,000 L/H of distilled water.

Salt Stress Inhibits Photosynthesis and Destroys Chloroplast Structure by Downregulating Chloroplast Development-Related Genes in Robinia pseudoacacia Seedlings.

Soil salinization is an important factor limiting food security and ecological stability. As a commonly used greening tree species, Robinia pseudoacacia often suffers from salt stress that can manifest as leaf yellowing, decreased photosynthesis, disintegrated chloroplasts, growth stagnation, and even death. To elucidate how salt stress decreases photosynthesis and damages photosynthetic structures, we treated R. pseudoacacia seedlings with different concentrations of NaCl (0, 50, 100, 150, and 200 mM) for 2 weeks and then measured their biomass, ion content, organic soluble substance content, reactive oxygen species (ROS) content, antioxidant enzyme activity, photosynthetic parameters, chloroplast ultrastructure, and chloroplast development-related gene expression. NaCl treatment significantly decreased biomass and photosynthetic parameters, but increased ion content, organic soluble substances, and ROS content. High NaCl concentrations (100-200 mM) also led to distorted chloroplasts, scattered and deformed grana lamellae, disintegrated thylakoid structures, irregularly swollen starch granules, and larger, more numerous lipid spheres. Compared to control (0 mM NaCl), the 50 mM NaCl treatment significantly increased antioxidant enzyme activity while upregulating the expression of the ion transport-related genes Na+/H+ exchanger 1(NHX 1) and salt overly sensitive 1 (SOS 1) and the chloroplast development-related genes psaA, psbA, psaB, psbD, psaC, psbC, ndhH, ndhE, rps7, and ropA. Additionally, high concentrations of NaCl (100-200 mM) decreased antioxidant enzyme activity and downregulated the expression of ion transport- and chloroplast development-related genes. These results showed that although R. pseudoacacia can tolerate low concentrations of NaCl, high concentrations (100-200 mM) can damage chloroplast structure and disturb metabolic processes by downregulating gene expression.

Molecular dynamics simulation of ethanol electrohydrodynamic atomization: Microscopic mechanism of the operating parameter effects

Electrohydrodynamic (EHD) atomization is a physical process, in which a liquid subjected to an external strong electric field and pumped through a capillary tube, disintegrates into monodisperse fine drops. In present work, EHD atomization behaviors under various operating parameters were numerically investigated using molecular dynamics (MD) methods. Good agreement was obtained between the MD simulations and the previous experimental work. The effects of electric potential, liquid flowrate, sodium chloride concentration and temperature on EHD atomization process were systematically examined, analyzed and discussed from the microscopic perspective. The results show that the jet length and the number of ethanol molecules ejected from capillary tube increased with an increase in electric Bond number. As the electric Bond number increases, the interaction between ethanol molecules decreases, and the hydrogen bond number reduces. As the Weber number increases, the jet length also increases, and the jet morphology may change from ‘plump’ to ‘sharp,’ and finally disrupts into liquid fragments. Sodium chloride plays an important role in the formation of atomization mode. With increasing ions concentration, a continuous jet can convert into dripping, which results from that the ions could destroy the stable structure of hydrogen bond among ethanol molecules. Furthermore, the ethanol clusters would gradually increase in size as the sodium chloride ion concentrations increasing. In addition, the movement of cations is inseparable from the breakup of the jet. The trend of individual atom motion in an ethanol molecule increases with an increase in temperature. This work provides a microscopic insight into EHD atomization and will be potentially useful for optimizing operating parameters and improving efficiency.

Exploring the effect of ion concentrations on the electrode activity and stability for direct alkaline seawater electrolysis

Studying the electrode activity and stability changes caused by the increasing ion concentration during the alkaline seawater electrolysis is crucial to exploit industrial-level seawater electrolyser. Herein, the concentration of hydroxide ion (OH−), chlorine ion (Cl−), and the other ions in alkaline seawater (OIAS) is investigated to understand the activity and stability for nickel foam (NF) electrodes as both hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) electrodes. As a whole, the activity of HER electrode is mainly dropped with the increasing concentration of OH−, while the OER electrode is enhanced with the increasing concentration of OH− and Cl−. However, the all (OH−, Cl− and OIAS) increasing ion concentrations decrease the HER electrode stability, while the Cl− reduces, the OH− and OIAS enhances the stability of OER electrode. Moreover, the chloride evolution reaction (ClER) in 6 M NaOH with seawater can be ignored even though the concentration of salts in alkaline seawater reach to saturation.

Salt sensitive purely zwitterionic physical hydrogel for prevention of postoperative tissue adhesion.

Abdominal adhesions are a class of serious complications following abdominal surgery, resulting in a complicated and severe syndrome and sometimes leading to a Gordian knot. Traditional therapies employ hydrogels synthesized using complicated chemical formulations-often with click chemistry or thermal responsive hydrogel. The complicated synthesis process and severe conditions limit the extent of the hydrogels' applications. In this work, poly 3-[2-(methacryloyloxy)ethyl](dimethyl)-ammonio]-1-propanesulfonate (PSBMA) polymer was synthesized to self-assemble into physical hydrogels due to the inter- and intramolecular ion interactions. The strong static interaction bonding density has a substantial impact on the gelation and physicochemical properties, which is beneficial to clinical applications and offers a novel way to obtain the desired hydrogel for a specific biomedical application. Intriguingly, this PSBMA polymer can be customized into a transient network with outstanding antifouling capability depending on the ion concentration. As ion concentration increases, the PSBMA hydrogel dissociated completely, endowing it as a candidate for adhesion prevention. In the cecum-sidewall model, the PSBMA hydrogel demonstrated superior anti-adhesion properties than commercial HA hydrogel. Furthermore, we have demonstrated that this PSBMA hydrogel could inhibit the inflammatory response and encourage anti-fibrosis resulting in adhesion prevention. Most surprisingly, the recovered skins of cecum and sidewall are as smooth as the control skin without any scar and damage. In conclusion, a practical hydrogel was synthesized using a facile method based on purely zwitterionic materials, and this ion-sensitive, antifouling adjustable supramolecular hydrogel with great clinic transform potential is a promising barrier for preventing postoperative tissue adhesion. STATEMENT OF SIGNIFICANCE: The development of hydrogels with satisfactory coverage, long retention time, facile synthetic method, and good biocompatibility is vital for preventing peritoneal adhesions. Herein, we developed a salt sensitive purely zwitterionic physical hydrogel poly 3-[2-(methacryloyloxy)ethyl](dimethyl)-ammonio]-1-propanesulfonate (PSBMA) hydrogel to effectively prevent postoperative and recurrent abdominal adhesions. The hydrogel was simple to synthesize and easy to use. In the cecum-sidewall model, PSBMA hydrogel could instantaneously adhere and fix on irregular surfaces and stay in the wound for more than 10 days. The PSBMA hydrogel could inhibit the inflammatory response, encourage anti-fibrosis, and restore smoothness to damaged surfaces resulting in adhesion prevention. Overall, the PSBMA hydrogel is a promising candidate for the next generation of anti-adhesion materials to meet clinical needs.

Organ distribution of Nano-WC particles after repeated intratracheal instillation into the lungs of SD rats and subsequent organ injury

Nano-tungsten carbide (nano-WC) is widely used in composite materials due to its special physical and chemical properties. Owing to their small size, nano-WC nanoparticles easily enter organisms through the respiratory tract, which may cause health hazards. However, only a few studies have reported the toxicity of nano-WC. In this study, a 10 mg/kg nano-WC suspension and 0.9% normal saline were quantitatively perfused into the lungs of two groups of healthy male SD rats by tracheal instillation, and the in vivo pulmonary toxic effects were systematically evaluated. Additionally, as multiple organs and tissues are involved, systemic effects were observed throughout the body and mainly manifested as inflammatory damage. The concentrations of tungsten ions in various organs and alveolar lavage fluid were measured by ICP–MS, and the results showed that the lung was the target organ, as it had the highest concentration of ions. In addition, the abnormal increases in the tungsten ion concentrations in the liver and kidney may be closely related to the immune damage we observed. This study provides a theoretical basis and data support for the systematic evaluation of the health hazards of nano-WC and a reference for the safe use of nanomaterials.

Residence Time Distribution Analysis of Drip-Irrigated Beds—The Effect of Material and Fluid Properties with Implications for Heap Leaching Practice

The quantitative effect of particle shape, porosity, wettability, particle size, and solution viscosity on the residence time distribution (RTD) profiles of non-reactive, steady-state, drip-irrigated ore beds characteristic of heap leaching systems is presented. Results were obtained using step-up tracer tests and allowed for the analysis of preferential flow behaviour within the systems. The key findings were as follows. Increased particle sphericity enhanced channelling in beds of smaller particles, but not for larger particle sizes. Higher particle wettability caused greater liquid dispersion during both initial wetting studies and at steady-state fluid flux. Higher porosity levels and the inclusion of fines in mixed sized beds resulted in longer average solute residence times, higher liquid hold-up, longer solution and tracer breakthrough times, and increases in drain-down moisture percentages. Increasing the irrigation fluid’s viscosity, reflective of the increase in ionic concentrations in leach solutions, reduced both the solution and tracer breakthrough times and increased dispersion with signs of more discontinuous or isolated fluid volumes at steady-state. These results highlighted the importance of the inclusion of fines in agglomerated beds to improve uniform wetting especially those with low to moderate particle porosities (<2.5 m2/g specific surface area). The viscosity results suggest that there may be changes in preferential flow extent, due to variations in viscosity owing to the increasing sulphate concentration within the liquid phase in heaps and with time.

Zwitterionic biodegradable physical hydrogel based on ATRP technology for effective prevention of postoperative tissue adhesion

Postoperative adhesions are one of the most common complications post intraperitoneal surgery. Even after the adhesiolysis, the recurrence of adhesions is as high as 85%. Although zwitterionic-based materials have been reported for the application, unlike the conventional zwitterionic hydrogel, a series of poly (sulfobetaine methacrylate) grafted dextran derivatives (Dex-g-PSBMA) were synthesized by atom transfer radical polymerization (ATRP) reaction, making it fined controllable copolymer by its living polymerization property. Intriguingly, the Dex-g-PSBMA copolymer can self-assemble into a physical hydrogel under physiological conditions. When injected at the site of the lesions, it can immediately cover the wound area, and as the ion concentration increases, the chemical bonds dissociate and the hydrogel may degrade completely. In the abdominal wall-cecum injury adhesion model in rats, Dex-g-PSBMA hydrogel showed excellent anti-adhesion ability, effectively preventing postoperative abdominal wall-cecum adhesion. The mechanism exploration revealed that Dex-g-PSBMA hydrogel can take an effect on the TGF-β/Smad signaling pathway, which can inhibit the Smad3 and activate the Smad7 pathway, thereby reducing the probability of tissue fibrosis, reducing fibrin deposition, and resisting fibroblast adhesions. In conclusion, these findings demonstrated that this Dex-g-PSBMA physical hydrogel is a promising candidate for completely preventing post-surgical adhesions.

Synthesis of tunable near infrared absorbance of gold nanorods (AuNRs) and their gold oxidation states during nanorod formation following by synchrotron based X-ray absorption spectroscopy (XANES)

A study of growth mechanism on AuNRs synthesized using seed-mediated method has been conducted via time resolved synchrotron based XAS. The synthesized AuNRs were characterized by TEM and UV–vis spectroscopy. It was found that the volume change of AgNO3 solution influenced their surface plasmon resonances (SPR) of AuNRs. An increase of silver ions concentration resulted in an increase of the aspect ratio (AR). For the growth mechanism investigation, time-resolved XANES in fluorescent mode and UV–vis measurement were employed. The potential growth mechanism was proposed according to the XANES spectrums. The reduction of Au(3+) oxidation state to Au(0) occurs after the reducing agent were added. The change in oxidation state of the AuNRs corresponded to the XANES spectrum of AuCl illustrating the oxidation states were reduced from Au(3+) to Au(+) then Au(0), respectively. Moreover, the rate of change in oxidation state depended on the AR. The formation of AuNRs was completed for the shorter rods (AR∼2.0) while the longer rods (AR∼4.2) still exhibit higher feature of oxidation state compared at the same reaction time. In addition, the change in absorbance from UV–vis spectrums revealed that AuNRs with AR∼2.0 took 50 min to complete rod formation which is faster than that of the AuNRs with AR∼4.2 (60 min). These UV–vis results were in a good agreement with the XANES spectrums. This finding leaded to conclude that the rod formation of AuNRs with lower AR could occurred faster than the formation of AuNRs with higher AR.

Methodical study of chromium (VI) ion adsorption from aqueous solution using low-cost agro-waste material: isotherm, kinetic, and thermodynamic studies.

This study involved preparation and modification of Saccharum officinarium as adsorbent used for the removal of chromium (VI) ions in a batch process. The adsorbent was modified with oxalic acid for improved performance of the adsorbent by increasing the surface area of the adsorbent. Surface morphology of the adsorbents was characterized by scanning electron microscopy (SEM) and X-ray diffraction (XRD), while Fourier transform infrared (FT-IR) analysis was carried out before and after the adsorption of Cr (VI) ions to determine the participating functional group in the processes. The optimum adsorption was attained at pH 2 and contact time of 180min with efficiency of adsorption of 56.7 and 92.6% onto RSO and MSO, respectively. The adsorption capacity increases with increase in initial metal ion concentration of the sorption mixture. The isotherms studies indicate that the experimental data were best fitted to Freundlich, Langmuir, and Sips models with R2 = 0.999 for adsorption of Cr (VI) ions onto raw S. officinarium (RSO) and modified S. officinarium (MSO). The maximum adsorption capacity obtained were 227.27 and 243.90mg*g-1 while the adsorption energy obtained from D-R were found to be 3.460 and 6.325kJ*mol-1 onto RSO and MSO, respectively. This revealed that the physiosorption process was favored in interaction of Cr (VI) ions onto both adsorbents. Separation factors obtained showed that the process is favored with increase in initial concentration of the adsorbate. Thermodynamic parameter values obtained showed that the sorption of Cr (VI) ions onto RSO and MSO is feasible, spontaneous, and endothermic in nature. The positive value of ΔS° indicates increase in disorderliness of the adsorption process. Kinetic data achieved at different initial concentrations of adsorbate have been analyzed, and the mechanism of the reaction was also studied by intra-particle and Bangham kinetic model. Each of the models was tested with R2 ˃ 0.9, where pseudo-second-order is the best-fitted model and Bangham mechanism only fitted with adsorption of Cr (VI) ions onto RSO. The reusability potential of RSO and MSO contributes to the economic values and reliability of the adsorbents for removal of Cr (VI) ions from aqueous solution.

Decoding Natural Astrocyte Rhythms: Dynamic Actin Waves Result from Environmental Sensing by Primary Rodent Astrocytes.

Astrocytes are key regulators of brain homeostasis, equilibrating ion, water, and neurotransmitter concentrations and maintaining essential conditions for proper cognitive function. Recently, it has been shown that the excitability of the actin cytoskeleton manifests in second-scale dynamic fluctuations and acts as a sensor of chemophysical environmental cues. However, it is not known whether the cytoskeleton is excitable in astrocytes and how the homeostatic function of astrocytes is linked to the dynamics of the cytoskeleton. Here it is shown that homeostatic regulation involves the excitable dynamics of actin in certain subcellular regions of astrocytes, especially near the cell boundary. The results further indicate that actin dynamics concentrate into "hotspot" regions that selectively respond to certain chemophysical stimuli, specifically the homeostatic challenges of ion or water concentration increases. Substrate topography makes the actin dynamics of astrocytes weaker. Super-resolution images demonstrate that surface topography is also associated with the predominant perpendicular alignment of actin filaments near the cell boundary, whereas flat substrates result in an actin cortex mainly parallel to the cell boundary. Additionally, coculture with neurons increases both the probability of actin dynamics and the strength of hotspots. The excitable systems character of actin thus makes astrocytes direct participants in neural cell network dynamics.