Search Results (45)

Renal function refers to the combined actions of the glomerulus and tubular system to achieve homeostasis in bodily fluids. While the glomerulus is essential in the first step of urine formation through a coordinated filtration mechanism, the tubular system carries out active mechanisms of secretion and reabsorption of solutes and proteins using specific transporters in the epithelial cells. The assessment of renal function usually focuses on glomerular function, so the tubular function is often underestimated as a fundamental part of daily clinical practice. Therefore, it is essential to properly understand the tubular physiological mechanisms and their clinical association with prevalent human pathologies. This review discusses the primary solutes handled by the kidneys, including glucose, amino acids, sodium, potassium, calcium, phosphate, citrate, magnesium and uric acid. Additionally, it emphasizes the significance of physicochemical characteristics of urine, such as pH and osmolarity. The use of a concise methodology for the comprehensive assessment of urine should be strengthened in the basic training of nephrologists when dealing with problems such as water and electrolyte balance disorders, acid-base disorders, and harmful effects of commonly used drugs such as chemotherapy, antibiotics, or diuretics to avoid isolated replacement of the solute without carrying out comprehensive approaches, which can lead to potentially severe complications. Full article

We report on a series of SrMo_1−xMn_xO_3−δ perovskite oxides designed as potential anode materials for solid oxide fuel cells (SOFCs). These materials were synthesized using a citrate method, yielding scheelite-type precursors with nominal SrMo_1−xMn_xO₄ compositions, which were further reduced to obtain the active perovskite oxides. Their structural evolution was examined through X-ray diffraction (XRD) and neutron powder diffraction (NPD). These techniques provided insights into the crystallographic changes upon Mn doping, revealing key factors influencing ionic conductivity. Whereas the oxidized scheelite precursors are tetragonal, space group I4₁/a, the reduced perovskite specimens are cubic, space group Pm-3m, and show the conspicuous absence of oxygen vacancies, even at the highest temperature of 800 °C. The transport properties were analyzed through electrical conductivity measurements, exhibiting a metallic-like behavior. Thermogravimetric analysis (TGA) and dilatometry give insights into the thermal stability and expansion behavior, essential for SOFC operation. Test single SOFCs were built in an electrolyte-supported configuration, on LSGM pellets of 300 μm thickness, assessing the performance of the title materials as anodes. This work emphasizes the critical relationship between the crystal structure and its electrochemical behavior, providing a deeper understanding of how doping strategies can optimize fuel cell performance. Full article

Magnetic fields influence the deposition process and its current efficiency. They have a remarkable influence on thin films’ surface characteristics and catalytic properties. Here, we study the correlation between the magnetic flux density and the current efficiency of the deposition process in the presence of a magnetic field with different intensities in different directions: the directions parallel and perpendicular to the electrode surface. We also show how the magnetic field direction impacts the surface roughness. Furthermore, we also analyze the impact of these synthesized films on the hydrogen evolution reaction (HER) when using them as electrocatalysts and how the application of a magnetic field in two dissimilar orientations influences the surface roughness and wettability. The synthesized Ni films are characterized using a scanning electron microscope (SEM), X-ray diffraction (XRD), and atomic force microscopy (AFM). Full article

In observing the electrocatalytic current of nanoparticles (NPs) using single-entity electrochemistry (SEE), the surface state of the NPs significantly influences the SEE signal. This study investigates the influence of capping agents on the electrocatalytic properties of gold (Au) NPs using SEE. Two inner-sphere reactions, hydrazine oxidation and glucose oxidation, were chosen to explore the SEE characteristics of Au NPs based on the capping agent presence. The results revealed that “capping agent-free” Au NPs exhibited signal magnitudes and frequencies consistent with theoretical expectations, indicating superior stability and catalytic performance in electrolyte solutions. In contrast, citrate-capped Au NPs showed signals varying depending on the applied potential, with larger magnitudes and lower frequencies than expected, likely due to an aggregation of NPs. This study suggests that capping agents play a crucial role in the catalytic performance and stability of Au NPs in SEE. By demonstrating that minimizing capping agent presence can enhance effectiveness in SEE, it provides insights into the future applications of NPs, particularly highlighting their potential as nanocatalysts in energy conversion reactions and environmental applications. Full article

The main drawback of seawater batteries that use the aluminum (Al)–air system is their susceptibility to anode self-corrosion during the oxygen evolution reaction, which, in turn, affects their discharge performance. This study consist of an electrochemical investigation of pure Al, 6061 Al alloy, and both types coated with zinc as an anode in a 3.5% sodium chloride (NaCl) electrolyte. The electrolyte solution used for the deposition of zinc metal contained citrate, with and without EDTA as a complexing agent. Subsequently, the performance of the anode was tested in a seawater battery, using a carbon@MnO₂ cathode and a 3.5% NaCl electrolyte. The performance of Al–air batteries has been significantly enhanced by applying a process of electrodepositing zinc (Zn) with a citrate deposition electrolyte solution in both pure aluminum and alloy 6061. The performance of the battery was further enhanced by adding EDTA as a chelating agent to the citrate-based electrolyte solution. The Al–air battery with aluminum alloy 6061 with Zn electrodeposition with an additional EDTA as the anode, carbon@MnO₂ as the cathode, and NaCl 3.5% solution as the electrolyte has the highest battery performance, with a specific discharge capacity reaching 414.561 mAh.${\mathrm{g}}^{-1}$ and a specific energy density reaching 0.255 mWh.${\mathrm{g}}^{-1}$, with stable voltage at 0.55 V for 207 h. Full article

Hard ceramic coatings were successfully prepared on the surface of ZM5 magnesium alloy by micro-arc oxidation (MAO) technology in silicate and aluminate electrolytes, respectively. The optimization of hard ceramic coatings prepared in these electrolyte systems was investigated through an orthogonal experimental design. The microstructure, elemental composition, phase composition, and tribological properties of the coatings were characterized by scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDS), X-ray diffraction (XRD), and tribological testing equipment. The results show that the growth of the hard ceramic coatings is significantly influenced by the different electrolyte systems. Coatings prepared from both systems have shown good wear resistance, with the aluminate electrolyte system being superior to the silicate system in performance. The optimized formulation for the silicate electrolyte solution has been determined to be sodium silicate at 8 g/L, sodium dihydrogen phosphate at 0.2 g/L, sodium tetraborate at 2 g/L, and potassium hydroxide at 1 g/L. The optimized formulation for the aluminate electrolyte solution consists of sodium aluminate at 5 g/L, sodium fluoride at 3 g/L, sodium citrate at 3 g/L, and sodium hydroxide at 0.5 g/L. Full article

Titanium anodic memristors were prepared in phosphate buffer (PB) and citrate buffer (CB) electrolytes. Studying their I-U sweeps, the memristors presented self-rectifying and volatile behaviors. Transmission electron microscopic analysis revealed crystalline protrusions inside a semi-crystalline Ti oxide. Grounded in this, a hybrid interfacial memristive switching mechanism relaying on partial filaments was proposed. Moreover, both analyzed memristor types demonstrated multilevel switching capabilities. The memristors anodized in the PB and CB showed high-to-low resistance ratios of 4 × 10⁴ and 1.6 × 10², respectively. The observed (more than two order of magnitude) ratio improvement of the PB memristors suggests their better performance, in spite of their modestly high resistive state instabilities, attributed to the thermal stress caused by consecutive switching. The endurance and retention of both the PB and CB memristors was measured over up to 10⁶ cycles, indicating very good lifetimes. Phosphate incorporation into the anodic oxide was confirmed by photoelectron spectroscopy analysis and was related to the improved memristive behavior of the PB sample. The presence of phosphate inside the memristively active layer modifies the availability of free O species (vacancies and ions) in the oxide. Taking all this into consideration, Ti anodic memristors anodized in PB are emphasized as candidates for neuromorphic computing. Full article

Despite features of cost-effectiveness, high safety, and superior capacity, aqueous zinc-ion batteries (ZIBs) have issues of uncontrolled dendritic cell failure and poor Zn utilization, resulting in inferior cycling reversibility. Herein, the environmentally friendly and naturally abundant sodium citrate (SC) was adopted as a dual-functional additive for ZnSO₄-based (ZSO) electrolytes. Owing to the abundant hydrogen-bond donors and hydrogen-bond acceptors of SC, the Zn²⁺-solvation shell is interrupted to facilitate Zn desolvation, resulting in inhibited corrosion reactions. Additionally, sodium ions (Na⁺) from the SC additive with a lower effective reduction potential than that of zinc ions (Zn²⁺) form an electrostatic shield inhibiting the formation of initial surface protuberances and subsequent Zn dendrite growth. This assists in the Zn three-dimensional (3D) diffusion and deposition, thereby effectively enhancing cycling stability. Specifically, a long cycling lifespan (more than 760 h) of the Zn//Zn symmetric cell is achieved with a 2 M ZSO-1.0 SC electrolyte at a current density of 1 mA cm⁻². When coupled with the NaV₃O₈·1.5 H₂O (NVO) cathode, the full battery containing SC additive exhibited a capacity retention rate (40.0%) and a cycling life of 400 cycles at a current density of 1 A g⁻¹ compared with that of pure ZnSO₄ electrolyte (23.8%). This work provides a protocol for selecting an environmentally friendly and naturally abundant dual-functional electrolyte additive to achieve solvation shell regulation and Zn anode protection for the practical large-scale application of ZIBs. Full article

This work presents the structural and electrical characterization of K₂NiF₄-type layered perovskites of LaSrAl_1−xMg_xO_4−δ composition to be used as oxide–ion electrolytes for a solid-oxide fuel cell (SOFC). These perovskites were prepared by mechano-chemical synthesis (ball milling), an alternative to traditional synthesis methods such as citrate-nitrates and solid-state reaction. With these methods, two things are avoided: first, the use of nitrate salts, which are more environmentally harmful than oxide precursors, and second, it saves the series of long thermal treatments associated with solid-state reactions. After grinding the precursors, nanometric particles were obtained with a combination of crystalline regions and amorphous regions; this effect was determined by XRD and TEM, showing that Mg has a positive effect on the phase formation by only mechanical synthesis. R2C4: After sintering, it was found by XRD that the sample x = 0.1 only presents the diffraction peaks corresponding to the desired phase, which shows a phase purity greater than 97%, even higher than that of the standard undoped sample. For x = 0.2 and 0.3, there was a segregation of impurities, possibly by the local migration of La and Sr heavy cations; this was determined by SEM and EDS. The electrical characterization of the sintered pellets was carried out by electrochemical impedance spectroscopy, which determined that the incorporation of Mg in the structure improves the ionic conductivity by three orders of magnitude, obtaining conductivities of 1.6 mS/cm at 900 °C for x = 0.2. Although the improvement in conductivity is considerable, many challenges such as densification, the segregation of impurities, and the study of mechanical and thermal properties must be carried out on these materials to endorse them as solid electrolytes in SOFC. Full article

Zinc–tungsten coatings have been considered as environmentally friendly, and corrosion- and wear-resistant coatings. Here, Zn–W coatings were successfully electrodeposited from an aqueous solution. Citrate-based electrolytes with pH in the range of 3.0 to 5.7 were used as plating baths. The kinetics of co-reduction in the Zn(II)–W(VI)–Cit system was studied on the basis of partial polarization curves. The effects of applied potential, electrolyte composition, pH, hydrodynamic conditions and passed charge on the electrodeposition of Zn–W layers were determined. X-ray photoelectron spectroscopy confirmed the presence of metallic tungsten co-deposited with zinc. X-ray diffraction analysis revealed the formation of hexagonal Zn–W phase resulting from a substitution of Zn atoms by W atoms in the Zn crystal lattice. The formation of the proper stable and electroactive W(VI) and Zn(II) complexes is the first crucial factor enabling the induced codeposition of Zn–W alloys. The tungsten content in the Zn–W deposit is closely related to the concentration of electroactive tungstate–citrate species and its ratio relative to the zinc–citrate electroactive species in the electrolytic bath. The oxidation state of tungsten in the electrodeposited Zn–W layers can be controlled mainly by the applied deposition potential and by the bath pH, which determines the type of W(VI)–Cit species that can be reduced. Full article

This paper deals with the properties and testing of newly prepared organic pigments based on melamine cyanurate containing magnesium or zinc cations depending on their composition and anticorrosive properties in model coatings. Organic pigments based on melamine cyanurate with Mg²⁺ in the form of a complex differing in the ratio of melamine and cyanurate units were prepared. Furthermore, a pigment based on melamine citrate with magnesium cation Mg²⁺, a pigment based on melamine citrate with magnesium cation, and a pigment based on melamine cyanurate with zinc cation were prepared. The properties of Mg-containing organic pigments were also compared with those of selected magnesium-containing inorganic oxide-type pigments. The above-synthesized pigments were characterized by inductively coupled plasma-optical emission spectroscopy, elemental analysis, scanning electron microscopy, and X-ray diffraction. In addition, the basic parameters that are indicative of the applicability of the pigments in the binders of anti-corrosion coatings were determined. The anti-corrosive properties of the tested pigments were verified after application to the epoxy-ester resin-based paint binder in three different concentrations: at pigment volume concentrations of 0.10%, 0.25%, and 0.50%. The anticorrosive effectiveness of pigmented organic coatings was verified by cyclic corrosion tests in a salt electrolyte fog (NaCl + (NH₄)₂SO₄) in an atmosphere containing SO₂ and by the electrochemical technique of linear polarization. Finally, the effect of the structure of the pigments on the mechanical resistance of the organic coatings was investigated. The results obtained showed that the new organic pigments exhibit anticorrosive properties, and at the same time, differences in performance were found depending on the structure of the pigments tested. Specifically, the results of cyclic corrosion tests and the electrochemical technique of linear polarization clearly demonstrated that synthesized pigments of the organic type based on melamine cyanurate containing magnesium or zinc cations ensure the anti-corrosion efficiency of the tested organic coatings. The highest anti-corrosion efficiency was achieved by the system pigmented with synthesized melamine cyanurate with magnesium cation (C₁₂H₁₆MgN₁₈O₆), whose anti-corrosion efficiency was comparable to the anti-corrosion efficiency of the tested inorganic pigment MgFe₂O₄, which was prepared by high-temperature solid-phase synthesis. In addition, these organic coatings achieved high mechanical resistance after being tested using the most used standardized mechanical tests. Full article

The effect of current density and bath temperature in the electroplating process on resistance to corrosion of Zn-Ni alloys was evaluated in this work. The electrolytic bath consisted of nickel sulfate, zinc sulfate, sodium sulfate, boric acid, and sodium citrate at pH 7.0. The current density was varied in the range 20–80 mA/cm² and the bath temperature in the range 30–60 °C. Increasing, independently, the current density or the bath temperature increased the nickel content in the obtained alloy, which affected the alloy microstructure, with a predominant γ phase and cauliflower-like morphology. The nickel content in the alloys was in the range 20–42%wt. A synergistic effect between the current density and bath temperature was observed from a design of experiments and response surface models. The maximum resistance to corrosion occurred for the alloy containing 42%wt. nickel. This alloy was obtained at upper levels of current density and bath temperature, presenting a corrosion potential of −0.789 V and polarization resistance of 4136 $\mathsf{\Omega }$.cm². Full article

Ni thin films were synthesized through the electrodeposition method from three different electrolytes (acetate, borate, and citrate). Furthermore, they were assessed as electrocatalysts for hydrogen evolution reaction (HER) in 1 M NaOH. Herein, various electrodeposition parameters, such as the pH of the electrolytes, the deposition potential, and the influence of the magnetic field, were measured. We compared the different morphologies and characteristics depending on the thin film electrodeposition process parameters. Moreover, we studied the material’s wettability changes based on the electrolyte’s composition and the applied external magnetic field. It was found that the deposited Ni thin film from the citrate electrolyte under the influence of the magnetic field in the perpendicular direction to the electrode surface had the best catalytic performance to HER. It possessed an overpotential value of 231 mV and a Tafel slope of 118 mV dec⁻¹. The deposition process was accomplished by using the chronoamperometry technique. Measuring scanning electron microscope and X-ray diffraction were used to characterize the fabricated films’ surface morphologies and crystalline structures. Full article

Cold stress is one of the major abiotic stresses that limits the growth and development of plants. Improving the cold tolerance of plants is essential to enhance crop productivity in the changing environment. OPEN STOMATA 1 (OST1), also known as sucrose non-fermenting 1 related protein kinases 2.6/2E (SnRK2.6/SnRK2E), has been reported to involved in cold stress response in plants. This interesting protein is confined to expressed in guard cells and vascular system. However, the detailed mechanism of how OST1 regulates cold stress, especially at the metabolomic level is largely unknown. In this study, metabolomic profiling of ost1 mutant and WT Arabidopsis plants under cold stress was investigated. The results showed that ost1-4 mutants displayed cold sensitive phenotypes compared with the WT plant, as evidenced by higher MDA content and electrolyte leakage and lower photosynthetic characteristics. Next, the metabolic changes between ost1-4 and WT plants in response to cold stress was analyzed by using the GC-TOF-MS system. The results showed that numbers of metabolites were identified to be related to OST1 regulated cold stress response. A large portion of the metabolites were carbohydrates and organic acids. The KEGG enrichment analysis revealed that the alanine, aspartate and glutamate metabolism, cyanoamino acid metabolism and citrate cycle (TCA cycle) were presumptive pathways that most related to OST1 regulated cold stress response. Gene expression such as AtGDHs, AtPPC1 and AtAK1 was also in line with the metabolic changes in the presumed pathways. Overall, this study provides fundamental knowledge for understanding the underlying metabolic mechanisms of OST1 mediated cold stress response in plants. Full article

Porous carbon electrode materials are utilized in supercapacitors with very fast charge/discharge and high stability upon cycling thanks to their electrostatic charge storage mechanism. Further enhancement of the performance of such materials can be achieved by doping them with heteroatoms which alter the kinetics of charge/discharge of the adsorbed species and result in pseudocapacitance phenomena. Here, microporous N-doped activated carbons were synthesized by thermochemical activation process. The structure and composition of the final material were adjusted by tuning the synthesis conditions and the choice of precursor molecules. In particular, N-doped activated carbons with a controlled specific surface area in the range of 270–1380 m²/g have been prepared by KOH-activation of sucrose/ammonium citrate mixture. By adjusting the composition of precursors, N-doping was varied from ca. 1.5 to 7.3 at%. The role of the components and synthesis conditions on the composition and structure of final products has been evaluated. The N-doped activated carbon with optimized structure and composition has demonstrated an outstanding performance as electrode material for aqueous electrolyte supercapacitors. The specific capacitance measured in a 3-electrode cell with 0.75 mg/cm² loading of optimized activated carbon in 1M H₂SO₄ changed from 359 F/g at 0.5 A/g charging rate to 243 F/g at 20 A/g. Less than 0.01% of capacitance loss has been detected after 1000 charging/discharging cycles. Full article