Concentrated Potassium Research Articles

Multinuclear PFGSTE NMR description of 39K, 23Na, 7Li, and 1H specific activation energies governing diffusion in alkali nitrite solutions

While pulsed field gradient stimulated echo nuclear magnetic resonance (PFGSTE NMR) spectroscopy has found widespread use in the quantification of self-diffusivity for many NMR-active nuclei, extending this technique to uncommon nuclei with unfavorable NMR properties remains an active area of research. Potassium-39 (39K) is an archetypical NMR nucleus exhibiting an unfavorable gyromagnetic ratio combined with a very low Larmor frequency. Despite these unfavorable properties, this work demonstrates that 39K PFGSTE NMR experiments are possible in aqueous solutions of concentrated potassium nitrite. Analysis of the results indicates that 39K NMR diffusometry is feasible when the nuclei exhibit spin–lattice and spin–spin relaxation coefficients on the order of 60–100 ms and 50–100 ms, respectively. The diffusivity of 39K followed Arrhenius behavior, and comparative 23Na, 7Li, and 1H PFGSTE NMR studies of equimolal sodium nitrite and lithium nitrite solutions led to correlations between the enthalpy of hydration with the activation energy governing self-diffusion of the cations and also of water. Realizing the feasibility of 39K PFGSTE NMR spectroscopy has a widespread impact across energy sciences because potassium is a common alkali element in energy storage materials and other applications.

Investigation on Structural, Optical, and Thermal Properties of Graphene Oxide (GO) Nanoparticles

The aim of the study , A nanoparticles of graphene oxide (GO) was synthesized by modified Hummer’s method. A new approach to synthesis graphene is oxidizing graphite powder with mixture with concentrated Sulphuric acid (H2SO4), Sodium Nitrate (Na NO3) and Potassium permanganate (KMnO4), Currently,an improved method for the preparation of graphene Oxide was most common one. The Graphene Oxide (GO) was characterized by X-Ray diffractration, FT-IR Spectroscopy, UV Visible Spectroscopy , Raman Spectroscopy and TGA analysis. The X-ray diffractration (XRD) results of Graphene oxide nanoparticles was found to be 12.9 nm with a hexagonal crystal structure. Key Words: Graphene oxide, Hummer’s method,Graphite, X-ray diffratcration, FI-IR analysis,UV-Visible spectroscopy ,Raman spectroscopy and TGA-DTA analysis

Development and validation of an acid/alkaline digestion method for efficient microplastic extraction from wastewater treatment plant effluents: Sulfuric acid concentration and contact time do matter

Accurate analysis of microplastic particles (MPs) in environmental samples requires removal of interferences during sample preparation. Wastewater samples are interference-rich and thus particularly challenging, with concentrated sulfuric acid currently deemed impractical as a reagent. Therefore, this study aimed to establish a straightforward, effective, and safe method employing concentrated sulfuric acid and potassium hydroxide to eliminate interferents from effluent samples obtained from wastewater treatment plants (WWTPs). We found that 80 % sulfuric acid at room temperature with a brief contact time of 5 min was viable through a qualitative spot test involving 37 plastics categorized into three types (I, II, and III) based on their polymer structure's oxygen position. A quantitative assessment revealed that treatments involving H2SO4 and KOH (20 %, 24 h, 48 °C), either separately or in combination, had no discernible physical impact on the overall plastics, except for a subtle one for Type III plastics (e.g., nylon and PMMA) known to be labile under harsh pH conditions. This acid/alkaline digestion (AAD) method, incorporating such conditions for H2SO4 and KOH treatments, yielded a high mass removal efficacy (97.8 ± 2.4 %, n = 13) for eliminating natural particle interferents for primary, secondary, and tertiary effluent samples. Furthermore, the AAD method allowed for the determination of MPs in effluents with high surrogate particle recoveries (e.g., 95.1 % for larger than 500 μm size fraction). This method is readily adaptable to create appropriate protocols for different types of environmental matrices.

Influence of Contact Pressure and Flow Rate on the Performance of Anion Exchange Membrane Electrolysis

Hydrogen production by electrolysis is a key aspect of a climate-neutral economy. However, there are still weak points in the established low-temperature technologies such as high material costs in case of PEM electrolysis and poor dynamic operations in case of alkaline electrolysis. The emerging electrolysis technology, the anion exchange membrane (AEM) electrolysis, addresses these weaknesses and combines their advantages. Due to the solid polymer electrolyte and the alkaline environment, AEM water electrolysis is featured by a compact zero-gap cell design and inexpensive materials like non-noble metal catalysts. Hence, it offers the potential to a cost-effective and efficient electrolysis technology.To enable the breakthrough of this technology, we contribute by conducting performance evaluations of membrane electrode assemblies (MEAs) under application-oriented conditions. One focus is on non-noble metal MEAs with an active area of 25 cm2 operated with pure water and low concentrated potassium hydroxide solution.To ensure comparability of different MEAs, it is crucial to compare them at their performance optimum. This is achieved by determining the optimal set-up parameters like contact pressure and operation parameters like flow rate for each MEA type. Otherwise, deviation from the optimal operating point by up to 50 % may occur.The influence of the parameters contact pressure and flow rate on the MEA performance is discussed in this presentation. To investigate their impact, we analysed the MEAs in an electrolyser test station using polarisation curves, electrochemical impedance spectroscopy and load tests at constant current and constant voltage.Some of the results presented are obtained within the project “REVAL – reversible anion exchange membrane electrolysis” (funding code 03ZZ0732D) funded by the German Federal Ministry of Education and Research (BMBF).

Incapacité des logiciels d’aide à la prescription hospitaliers à sécuriser l’utilisation des solutions concentrées de potassium injectable

To determine whether hospital computerised physician order entry (CPOE) systems contribute to securing intravenous potassium chloride (KCl) prescriptions with reference to the recommendations issued by French healthcare agencies. We sent a questionnaire to the members of the Association pour le Digital et l'Information en Pharmacie. More than three quarters of the 84 responses received involving 23 CPOE systems indicate that it is possible to: prescribe an ampoule of concentrated potassium chloride 10% 10mL intravenously without any diluents (80%); prescribe 4g of KCl in a bag of 500mL of NaCl 0,9% (98%); prescribe a solution that contains 6 grams of KCl per liter (94%); prescribe the administration of an injectable ampoule orally by means of a free text comment (83%). Nearly half of the responses indicate that it is possible to prescribe: concentrated KCl ampoules as administration solvent (50%); an injectable vial to be administered by oral route (52%). At least 23 hospital CPOE systems are unable to secure the prescriptions of injectable KCl. This finding lifts the veil on an unthought, namely the role of CPOE systems in securing high-risk medications. In order to solve this problem, it should be mandatory that health information technology vendors pay particular attention to these drugs. With regard to injectable KCl, the utilisation of a dilution vehicle, maximum concentration and maximum infusion flow rate are the first four constraints to be satisfied.

Tunning solvation structure in non-flammable, localized high-concentration electrolytes with enhanced stability towards all aluminum substrate-based K batteries

Although metallic potassium or graphite anode with low redox potentials are desirable for potassium-ion batteries (PIBs), the severe capacity decay caused by consecutive reduction reactions on the aggressively reactive anode surface is inevitable because of the scarcity of an effective passivation layer. Additionally, the development of PIBs faces potential safety hazards due to the usage of reactive anodes with flammable electrolytes. Herein, a fire-retardant localized high-concentration electrolyte (LHCE) is formulated by adding a low-polarity co-solvent of highly fluorinated ether into the concentrated potassium bis(fluorosulfonyl)imide/trimethyl phosphate. A unique electrolyte solvation environment with the enhanced anion-cation interaction in an LHCE facilitates a durable anion-derived solid electrolyte interphase (SEI) with self-accelerated interfacial kinetics and minimizes the SEI dissolution compared to the conventional carbonate-based electrolyte. Consequently, the unmodified Al substrate could sustain stable potassium metal cycling above 3400 h (over 800 cycles) with high reversibility (98%), and the graphite anode retains prolonged cyclic stability (over 300 cycles) with a high reversible capacity (257.6 mAh g−1) and capacity retention (92.6 % at 0.2 C). Meanwhile, Al corrosion at high voltage is significantly suppressed, and the electrochemical window is extended due to less free solvents in an LHCE, enabling good electrolyte compatibility with high-voltage cathodes. Coupling non-flammable solvents and the concept of LHCE could facilitate a better understanding of electrolyte chemistry and offer more opportunities to use K or graphite anode for all Al substrate-based PIBs highlighted with high performance and superb safety.

Mg-Doped KFeSO4F as a High-Performance Cathode Material for Potassium-Ion Batteries

Potassium iron sulfate fluoride (KFeSO4F) is a high-voltage positive electrode material for potassium-ion batteries, but its practical performance remains limited due to its moderate electronic conductivity. In this study, we employed Mg ion doping in the Fe site of KFeSO4F to tune the crystallinity and ionic/electronic conductivity. Furthermore, we made a composite with carbon nanotubes to enhance the electrode’s electronic conductivity. In a K-ion cell filled with concentrated potassium bis(fluorosulfonyl)amide/triglyme electrolyte, the KFe0.95Mg0.05SO4F/CNT composite electrode delivers discharge (potassiation) capacities of 107 and 100 mAh g–1 in the first and 100th cycles at a rate of 0.1C with reasonable rate capability. UV–vis absorption spectroscopy studies of Mg-doped KFeSO4F powder samples showed a narrower band gap compared to KFeSO4F. Furthermore, from the combined results of X-ray diffraction and absorption spectroscopy studies, we found that multiple two-phase reaction mechanisms through the Fe3+/Fe2+ redox occurred during the reversible depotassiation/potassiation cycle.

Sustainable Alkali-Activated Slag Binders Based on Alternative Activators Sourced From Mineral Wool and Glass Waste

In the present study, four different locally available waste glass materials (bottle glass-BG, glass wool-GW, stone wool-SW and cathode-ray tube glass-CRTG) were treated with hot concentrated potassium hydroxide (KOH) in order to obtain alternative alkali activators (AAAs). We evaluated the suitability of the solutions obtained for use as AAAs in the production of AAMs. AAMs were prepared using electric arc furnace slag and selected AAAs with a higher content of dissolved Si. We evaluated the performance of the AAMs in comparison to that of slags activated with KOH or potassium-silicate (K-silicate). The compressive strength of the AAMs prepared with KOH-based AAAs were high when Si and Al were simultaneously abundant in the AAA (9.47 MPa when using the activator sourced from the CRTG), and low with the addition of KOH alone (1.97 MPa). The AAM produced using commercial K-silicate yielded the highest compressive strength (27.7 MPa). The porosity of the KOH-based AAM was lowest when an alternative BG-based activator was used (24.1%), when it was similar to that of the AAM prepared with a K-silicate. The BG-based activator had the highest silicon content (33.1 g/L), and NMR revealed that Si was present in the form of Q0, Q1 and Q2. The concentrations of toxic trace elements in the AAAs used for alkali activation of the slag were also determined, and leaching experiments were performed on the AAMs to evaluate the immobilisation potential of alkali-activated slag. In the SW AAAs the results show acceptable concentrations of trace and minor elements with respect to the regulations on waste disposal sites, while in the activators prepared from BG, CRTG and GW some elements exceeded the allowable limits (Pb, Ba, Sb, and As).

Reactions of Neptunium(V) in Alkali-Metal Hydroxides.

The preparation of two new neptunium hydroxide compounds synthesized in concentrated potassium and rubidium hydroxide is reported. The phases K4[(NpO2)2(OH)6]·4H2O and Rb4[(NpO2)4(OH)8]·2H2O were prepared and their chemical structures determined using single-crystal X-ray diffraction. Raman spectra of the compounds are also presented. The newly synthesized phases are structurally related to Np2O5 and Na[NpO2(OH)2]. The potassium-containing phase reported here consists of infinite chains of edge-sharing neptunium hydroxide polyhedra but lacking the cation-cation interactions (CCIs) observed in Np2O5 and Na[NpO2(OH)2]. Rb4[(NpO2)4(OH)8]·2H2O is a an expanded three-dimensional framework based on NpO2+ CCIs like those observed in Np2O5 and Na[NpO2(OH)2]. Together these complexes begin to develop a structural series of neptunium(V) oxides and hydroxides of varying dimensionalities within the alkali-metal series. The potential roles of the alkali-metal cations and neptunyl(V) CCIs in directing the resulting structures are discussed.

Towards Realizing High-Voltage Aqueous Zinc Batteries: An Investigation of the Zinc Anode in Concentrated Acetate-Based Electrolytes

Zinc-based aqueous battery systems are attractive for grid storage applications due to the inherent electrolyte safety, material non-toxicity, low cost, high volumetric capacity of zinc and the low polarizability of the zinc anode in aqueous solutions. Despite these key features, they possess lower energy density when compared to lithium-ion batteries primarily due to the limited working potential range for aqueous electrolytes. In addition, zinc hosts a slew of problems such as inhomogeneous material distribution upon cycling and the formation of inactive zinc species and dendrites, all of which contribute to capacity loss and ultimately, cell failure. Water-in-salt electrolytes (WiSE) have been found to be an effective strategy to expand the electrochemical window of aqueous electrolytes for high energy density aqueous-based batteries, including zinc batteries. There is a growing amount of literature on highly concentrated acetate-based electrolytes as low-cost and non-toxic WiSE for lithium, potassium, sodium and magnesium and zinc battery systems. However, work is scarce on the nature of zinc electrochemistry, morphology and reversibility in these concentrated electrolytes at realistic current densities (> 1 mA/cm2) and higher zinc utilization. Understanding the electrochemical behavior of zinc in this electrolyte system will significantly aid in the development of a high voltage zinc aqueous battery.In this work, the zinc electrochemical performance and surface morphology is studied in highly concentrated bi-salt potassium acetate (KOAc)-zinc acetate (Zn(OAc)2) electrolytes. The impact of the high concentration on the electrochemical working window of the electrolytes is measured using potential sweep and constant-current techniques. As the acetate concentration is varied from 1 m to 32 m, the largest electrochemical window is measured at 3.33 V for 31 m KOAc+ 1 m Zn(OAc)2. Zinc half cells are cycled at current densities of 1-5 mA/cm2 to examine zinc reversibility with respect to zinc depth-of-discharge (DOD) in these electrolytes. The zinc discharge product is visualized by in-operando optical microscopy as a function of the potential and is observed to be a zinc plating/stripping phenomenon in contrast to zinc dissolution/precipitation typically observed in alkaline media. Energy dispersive X-ray spectroscopy and X-ray diffraction studies display the minor presence of zinc oxide and zinc hydroxide after repeated cycling. Cloud point measurements are performed to measure the phase stability of these electrolytes at 5-25ºC as a function of acetate concentration, which show that concentrations below (and including) 27 m KOAc + 1 m Zn(OAc)2 does not induce crystallization at these temperatures. Preliminary measurements using spectroscopic techniques such as Raman and nuclear magnetic resonance (NMR) spectroscopy are conducted to elucidate ion solvation structures as a function of acetate concentration. Overall, the current and proposed studies are fruitful in understanding the relationship between zinc anode and the concentrated acetate-based electrolytes in the pursuit of a high-voltage aqueous zinc battery.

The effect of corrosive substances on fingermark recovery: A pilot study

Corrosive substance attacks have become a growing issue within the UK. Although most commonly occurring in gang-related offences, there are high profile instances where this type of attack has been used to attack women to disfigure and destroy livelihoods. Despite the increase in such attacks, there has been very little published research into the recovery of forensic evidence from items used in these crimes. The effect of corrosive substances on the recovery of different types of forensic evidence is unknown, and there is no guidance for laboratories processing exhibits contaminated with corrosive substances regarding optimum treatments. This pilot study focused on establishing the effectiveness of a range of fingermark visualisation processes in recovering fingermarks on surfaces exposed to concentrated sulfuric acid (acid) and potassium hydroxide (alkali). Results indicate that on non-porous surfaces vacuum metal deposition and powder suspensions remain effective, and on porous surfaces fingermarks could still be visualised with physical developer. Alkalis were found to be more detrimental than acid environments in this limited study. The results demonstrate that fingermark recovery is still feasible on surfaces exposed to corrosive substances and provides encouragement that treatment protocols could be developed for this type of exhibit.

Insight on the inhibitive property of potassium ion on the stability of shale: a diffuse double-layer thickness (\u03ba\u22121) perspective

It is believed that potassium ions reduce the hydration energy and swelling of clays and thus promoting stability to shales. This belief was made based on volumetric and linear expansion data obtained from shale and KCl solutions interactions. However, swelling data alone is not adequate to mitigate wellbore instability in shale. Such data must be incorporated with mechanical and physicochemical data for complete and accurate wellbore instability analysis.This paper presents clear experimental evidence showing that concentrated potassium chloride solutions tend to suppress shale swelling as higher concentration of potassium ions collapses the diffuse double layer of clay particles causing shale shrinkage which confirms the notion that the Debye length (κ−1) decreases as the ionic concentration increases.Results show that there exists a KCl concentration threshold above which shale’s compressive strength deteriorates significantly. This concentration threshold was found to hover around 5% by weight. The amount of water and ions uptake into shale was quantified using gravimetric measurements. Significant potassium ions invasion into shale was experimentally measured as KCl solution concentration increased which proved the leaky nature of shale’s membrane. The reduction of shale’s compressive strength seems to be well correlated with the amount of ions uptake into shale. Moreover, data suggests that shale’s compressive strength was not significantly impacted by swelling. It was possible to gravimetrically separate osmotic water from associated water as shale interacted with KCl solutions. Results suggest that osmotic water is responsible for shale swelling since it is unattached to ions which makes it free to move around inside shale. On the other hand, data suggest that associated water does not contribute to shale swelling as it is bound to potassium ions which makes it unfree to move around. It is fair to state, based on our experimental data, that osmotic water is responsible for shale swelling while associated water contributes to shale’s compressive strength alteration.

A modified Hummers soft oxidative method for functionalization of CNTs: Preparation, characterization and potential application for selective determination of norepinephrine

Functionalized carbon nanotubes, CNTs(COOH), of excess oxygen containing functional groups were prepared using a modified Hummers method. The method is based on oxidizing pristine carbon nanotubes (P-CNTs) by moderately concentrated sulfuric acid and potassium permanganate at low temperature to avoid possible CNTs fragmentation and to preserve the aspect dimensional ratio. The resulting compatible materials were characterized and confirmed by scanning electron microscopy (SEM), energy dispersive X-ray (EDX), Fourier transform infrared spectroscopy (FTIR), X-ray photoelectron spectroscopy (XPS) and electrochemical method including cyclic voltammetry (CV) and differential pulse voltammetry (DPV). Fabrication of a sensitive sensor was much reliable by directly casting of CNTs(COOH) onto the surface of a glassy carbon electrode, CNTs(COOH)-GCE, rather than the tradition electrochemically reduced deposition method, ER-CNTs(COOH)-GCE, which ultimately misplaces large number of surface oxides. The functionalized surface materials exhibited an exceptional electrochemical activity on norepinephrine (NOR) oxidation in the presence of high concentrations of electrochemical active interference species such as ascorbic acid (AA) and uric acid (UA). The proposed sensor was excellently passed the selectivity test and lowered the detection limit of NOR (DL3σ, NOR) into 0.035 μM (6 ppb). It was also applied successfully for detection of NOR in serum blood sample with tolerable recovery percentages.

Textured stainless steel foil as efficient rear reflector for flexible black silicon

This paper reports textured SS foil as an efficient rear reflector for flexible b-Si. Wafer thinning by concentrated potassium hydroxide (KOH) solution followed by metal-assisted chemical etching (MACE) are used to fabricate the flexible b-Si with 67 μm thickness. After the MACE process, the b-Si exhibit nanowires (NWs) with average diameter of 100 nm and height of 1.25 µm. To texture the stainless steel (SS) foil, wet chemical etching involving hydrofluoric (HF) acid (49%) is used at room temperature for different durations; from 10 to 30 min. When increasing the etching time of the SS foil, the SS foil exhibits formation of random textures with the roughest morphology after being etched for 20 min. At the same etching time, the SS foil also shows the highest root mean square (RMS) surface roughness and peak texture angle with a broad angle distribution. With the textured SS foil, the flexible b-Si demonstrates absorption enhancement of 1.27 at wavelength of 1075 nm due to the enhanced light scattering at the b-Si/textured SS interface.

Impact of HHO gas enrichment and high purity biodiesel on the performance of a 315 cc diesel engine

Biodiesel and oxyhydrogen (HHO) gas have shown promising results in improving engine performance and emissions. In this work, the effects of HHO gas and 5% biodiesel blends (B5) and their combined use in a 315 cc diesel engine have been analyzed. Biodiesel is produced by base catalyzed transesterification and cleaned by emulsification. Its calculated cetane index (CCI) was 61.4. HHO gas is produced from electrolysis of concentrated potassium hydroxide solution. The use of 5% biodiesel blend resulted in a significant rise of 9.4% in the brake thermal efficiency (BTE) and a maximum reduction of 8.19% in the brake specific fuel consumption (BSFC). HHO enrichment of diesel and biodiesel at 2.81 L/min through the intake manifold improved the torque and power by an average of over 3%. HHO addition also improved the BTE of diesel by a maximum of 3.67%. The combination of high CCI biodiesel fuel and HHO creates a mixture that has shortened the ignition delay (ID) to the point that adverse effects were observed due to the premature combustion as shown by the average decrease in the BTE of 2.97% compared to B5. Thus, B5, on its own, is found to be the optimum fuel under these conditions.

One-pot synthesis of pre-reduced graphene oxide for efficient production of high-quality reduced graphene oxide and its lithium storage application

Graphene oxide (GO) is the key for the large-scale production of graphene by chemical oxidation-thermal reduction route. However, the current synthesis methods of GO involve concentrated sulfuric acid and potassium permanganate, which poses a risk of explosion and potential environmental pollution. Furthermore, a large number of oxygen-containing functional groups cause GO sheets to swell, posing a major challenge to the purification process. In this paper, a one-pot hydrothermal method is developed to synthesize pre-reduced graphene oxide (PRGO). The precursor is then employed to produce reduced graphene oxide (RGO) by further high-temperature thermal reduction. It not only avoids the complex temperature control and dilution operations during the oxidation and exfoliation processes but also enables the recycling of sulfuric acid. The synthesized weakly hydrophilic PRGO is highly conducive to achieve rapid filtration, which simplifies the purification process. The obtained reduced graphene oxide exhibits high rate capability and stable long cycling performance as the anode of lithium-ion batteries. This simple, safe and green synthesis route paves the way to large-scale preparation of graphene and its application for Li-ion storage.

Vitamin D analyses in veterinary feeds by gas chromatography-tandem mass spectrometry.

This report examines the feasibility of determination of Vitamin D3, D2 and their 25-hydroxy metabolites utilizing Gas Chromatography Tandem Mass Spectrometry (GC/MS/MS) as a potential alternative to popular Liquid Chromatography Tandem Mass Spectrometric (LC/MS/MS) methodologies. The GC/MS/MS approach was found to operate reasonably well despite long-standing concerns that gas-liquid chromatography of vitamin D compounds invoke thermal rearrangements owing to the relatively high inlet and capillary column temperatures used. The workup procedure involved incubation of feed samples with concentrated potassium hydroxide for overnight fat saponification, extraction of D Vitamins in n-hexane and reaction with N,O-bis(trimethylsilyl)trifluoroacetamide at 70 °C for 30 mins. In addition to parent compounds, small amounts of pyro-, isopyro-, and iso-vitamin D and isotachysterol3 variants were obtained from each Vitamin D-related compound upon extraction and GC/MS/MS analysis. Mass spectral and chromatographic behavior of these compounds are herein described and interpreted. Multiple Reaction Monitoring settings on GC/MS/MS included m/z 456→351 for Vitamin D3 and m/z 486→363 for Vitamin D2. Trimethylsilylation enabled single predominant peaks for Vitamins D3 and D2, and sample workup in the presence of deuterated Vitamin D analogs enabled accurate and precise sensitivity to 1 ppb (ng/g) in feeds. The method could be extended with reasonable accuracy to 25-hydroxy (25OH) compounds, but accuracies would be significantly improved by inclusion of respective 25OH-specific deuterated internal standards. The method was applied to 27 submissions of suspect dog foods of which 22% were discovered elevated and 44% were discovered to contain toxic levels of Vitamin D3. The described method was thus discovered to provide a suitable mass spectrometric approach for Vitamin D, proving itself here specifically of value in detection of ergocalciferol and cholecalciferol in animal feeds. The specificity and sensitivity of the tandem quadrupole approach can enable suitable applicability to serum determination if desired.

An affordable option to Au single crystals through cathodic corrosion of a wire: Fabrication, electrochemical behavior, and applications in electrocatalysis and spectroscopy

Faceting and nanostructuring of polycrystalline gold electrodes by cathodic corrosion in concentrated potassium hydroxide electrolytes has been systematically studied at different electrode potentials. Current-potential curves for the restructured Au electrodes in 0.1 M H2SO4 show characteristics of Au(111) in the double-layer and oxidation region. Thus, the modified Au electrodes adopt properties typically known for well-defined single crystal surfaces. Besides the preferential surface faceting, the electrochemically active surface area (EASA) is enhanced as a function of potential, concentration and time. Scanning electron micrographs show the formation of triangular pits and nanostructures with a specific orientation confirming the formation of (111)-facets. In this way, the behavior of single crystals is accompanied with the properties of nanoparticles which are of utmost interest in electrocatalysis and surface-enhanced Raman spectroscopy (SERS). The electrocatalytic activity of the newly formed “Au(111)” surface from an Au wire has been tested towards the hydrogen evolution reaction (HER) and for the formic acid oxidation reaction (FAOR). The study of electrocatalytic reactions at these nanostructured electrodes allows to identify active centers, which are absent for extended single crystal surfaces. Adsorbed pyridine on the nanostructured Au electrodes directly shows SERS activity, while untreated polycrystalline Au is SERS-inactive. The use of cathodic corrosion of simple wires is a paradigm of SERS-applications in electrochemistry with clean Au electrodes that provide properties of Au(111) single crystals.

Correcting hypokalaemia in a paediatric patient with Bartter syndrome through oral dose of potassium chloride intravenous solution

Bartter syndrome is a rare autosomal recessive disorder characterized by hypokalaemia. Hypokalaemia is defined as low serum potassium concentration ˂3.5 mmol/L, which may lead to arrhythmia and death if left untreated. The aim of this case report was to normalize serum potassium concentration without the need for intravenous intervention. A 5-month-old male of 2.7 kg body weight diagnosed with Bartter syndrome was admitted to the general paediatric ward with acute severe hypokalaemia and urinary tract infection. The main challenge was the inability to administer drugs through intravenous route due to compromised body size. Therefore, we shifted the route of administration to the nasogastric tube/oral route. A total of 2 mL of concentrated intravenous potassium chloride (4 mEq potassium) were dissolved in distilled water and administered through nasogastric tube. Serum potassium concentration was rapidly normalized, which culminated in patient discharge. In conclusion, shifting drug administration from intravenous to oral route in a paediatric patient with Bartter syndrome includes numerous advantages such as patient convenience, minimized risk of cannula-induced infection, and reduced nurse workload.

Studies on Energy Cells Based on Si-, Si-Ge- and Ge-Air Systems

Silicon metal may be used as a fuel in Si-Air fuel cells. The most important characteristics of theseenergy cells is its thermodynamic reversibility. The Silicon-air energy cell is highly promising for electric vehicles due to its high theoretical energy density (8470 Wh kg-1) and its discharge products are non-toxic. For the first time, pure silicon and germanium powders are used as anode material. Nickel wire mesh embedded with charcoal and manganese dioxide powder as cathode and concentrated potassium hydroxide is used as electrolyte. Voltage-time curves have been presented in this study for pure silicon and germanium powder, and 5% and 10% germanium with silicon powder.