Bathing Solution Research Articles

Generation of oxygen interstitials with excess in situ Ga doping in chemical bath deposition process for the growth of p-type ZnO nanowires

The current work focuses on the incorporation of excess amount of gallium (Ga) in zinc oxide (ZnO) nanowires to generate oxygen interstitials for developing p-type conductivity. Ga has been used as an n-type dopant in ZnO lattice by reducing its inherent vacancies up to 3% molar ratio of Ga and Zn employing chemical bath deposition technique. However, the addition of more than 4% of gallium nitrate in the bath solution creates oxygen interstitials which are confirmed from the presence of X-ray photoelectron spectroscopy (XPS) peak at 532.6 eV and the relevant cathodoluminescence (CL) peak at 626 nm of the grown Ga-doped ZnO nanowires. The p-type conductivity of such ZnO nanowires has been confirmed from current–voltage, capacitance–voltage and Hall voltage measurements. The reproducibility of the results indicates the incorporation of excess Ga to be a promising technique for growing p-type ZnO nanowires.

Structural, optical, electrical and morphological properties of CdS films deposited by CBD varying the complexing agent concentration

Abstract CdS thin films were deposited on commercial glass substrates by CBD technique at constant temperature and deposition time of 90 °C and 50 min, respectively. The reaction was performed by mixing cadmium acetate, ammonium acetate, ammonium hydroxide, thiourea, and deionized water as an aqueous medium. The S/Cd ratio in the solution was kept constant at 4.46 to make sure that the films were as stoichiometric as possible. Optical, electrical, structural properties and the presence of organic compounds in the films were studied modifying the concentration of ammonium hydroxide (complexing agent) in the bath solution. X-ray diffraction patterns show that all films have the cubic phase with a preferential orientation in the plane (1 1 1). An increase of the film’s resistivity from 102 to 107 Ω-cm is observed by increasing the ammonium hydroxide concentration in the solution in the narrow interval of 0.18–0.36 M. Transmittance values up to 70% are obtained at the lowest concentrations of this reagent, obtaining from these spectra the highest value of the direct bandgap, 2.37 eV. Results about the presence of organic compounds and their influence on the photoluminescence properties are shown, which have not been reported to date. The main organic compound identified by FTIR is cyanamide, whose concentration is higher at the lowest ammonium hydroxide concentrations. Photoluminescence spectra of the films show green, red and orange bands, located at 2.27 eV, 1.78 eV, and 2.02 eV, respectively. An additional band was observed with low intensity at 2.99 eV associated with the presence of nanoparticles in some films. The films with the lower presence of defects, higher uniformity and best optical, electrical and structural properties for their use as window material in solar cells are those deposited from a bath solution with a 0.24 M concentration of the complexing agent.

THE EFFECT OF COPPER ION ON THE FILM FORMATION RATE OF TITANIUM-BASED NANOCERAMIC LAYER ON A MILD STEEL SURFACE

In this study, the effect of copper ion (Cu[Formula: see text]) was investigated on the film formation rate of Ti-based nanoceramic conversion layer on a ST12 type mild steel. At the first step, the film formation properties of the Ti conversion layer were characterized using DC polarization technique and FE-SEM micrographs. In the next step, concentration of Cu ion was optimized in the Ti solution bath, and finally, the rate of Ti ion (Ti[Formula: see text]) consumption in the conversion solution bath, with and without Cu ion, was detected by spectrophotometric technique using a dye-metal indicator. It was revealed that the addition of Cu ion to the Ti solution bath could increase the precipitation rate of Ti-based compounds on the mild steel substrate, leading to increment of film formation rate of the conversion layer.

Facile synthesis of TiO2/rGO neatly electrodeposited on carbon fiber applied as ternary electrode for supercapacitor

A direct and quick approach to performer rGO (reduced graphene oxide) and TiO2 (titanium oxide) depositions using electrochemical techniques to reduce GO on CF substrate (rGO/CF) with subsequent TiO2 nanoparticles electrodeposition to produce ternary nanocomposites TiO2/rGO/CF is presented. A new bath solution consisting of titanium chloride, H2O2 and supporting salt LiClO4 was develop in order to simplify and reduce the preparation time of TiO2 synthesis. Scanning electron microscopy images showed irregular and flakes-like shape aggregates with high particle density on CF substrate characteristic of rGO morphology. Homogeneous distribution of TiO2 nanoparticles on TiO2/rGO/CF surfaces were observed on graphene sheets without modifying their morphologies. The CV curves presented a quasi-rectangular shape, indicating that the charge storage occurs preferentially through of the TiO2/rGO/CF electric double layer. Galvanostatic tests showed the highest time of the charge/discharge for TiO2/rGO/CF_5 sample, probably attributed to its surface area increase, improving its charge storage capacity. These results assured that TiO2/rGO/CF ternary composite has great potential as new electrode for supercapacitor application.

Influence of thiourea on electroless Ni–P films deposited on silicon substrates

Electroless nickel–phosphorus films were produced on silicon substrates in alkaline bath solutions, with the addition of thiourea in a concentration range of 1.0–5.0 mg L−1. The influence of thiourea on the chemical composition, morphology and corrosion resistance of the films was studied. The results revealed thiourea had a major influence on plating rate, phosphorus-content and aggregate size. The optimal content of thiourea was 1 mg L−1. Thiourea accelerated the deposition rate at low concentration of 1 mg L−1, but deceased the deposition rate and the phosphorus content at high concentration. The surface of the film without thiourea was smooth and dense. Also, with increasing thiourea content, the surface evolved into coarse nodular morphology with clear intercolonial boundaries. With the addition of 1 mg L−1 thiourea, the film had better corrosion resistance compared to film without thiourea.

Hydrothermal syntheses of Vanadium doped [formula omitted] cubic particles with enhanced photoelectrochemical activity

Water splitting to produce hydrogen using semiconductor material has been a focus of intense research in last few years. The main challenge to accomplish this task is to find a suitable band gap, non-toxic and earth abundant material for photoelectrochemical (PEC) process. α-Fe2O3 is proven to be a suitable candidate for PEC process because of its stability, non-toxic nature, abundance is nature and a narrow band gap of (1.9–2.2 eV). In this work V-doped α-Fe2O3 cubic particles were deposited on ITO substrate by hydrothermal and annealing method. The composition of V was controlled in bath solution by changing the concentration of V from 0 to 3%. After successful deposition, all samples were characterized by structural studies using x-ray diffraction, morphological studies using scanning electron microscopy (SEM) and transmission electron microscopy (TEM), optical studies using UV–VIS spectroscopy to measure band gap (eV) and chronoamperometry was applied to measure photo response of samples. SEM and TEM studies revealed cubic particles with size varying from 350 nm to 400 nm. XRD studies confirms hematite structure for V-doped and undoped α-Fe2O3 samples. Optical studies show a variation of band gap from 1.89 eV ∼ 2.09 eV. Chronoamperometry studies revealed that 3%V-doped samples displayed 16 times higher PEC activity with respect to undoped α-Fe2O3film. The higher current density can be attributed to band gap narrowing and increased donor density. Result provided in this work can provide an imperative guideline for the design of efficient photocatalysis application using α-Fe2O3.

Using Sodium Polyacrylate Aqueous Solution to Replace Lead Bath for Patenting High-Strength Steel Rope Wire of Automobile Industry

Abstract In order to eventually eliminate the lead toxicity in the steel wire making industry and to protect our environment from pollution, a polymer quenchant, aqueous sodium polyacrylate (SPA) solution, was selected to replace the lead bath and used as a substitution quenchant in patenting of high strength and precise steel rope wire for a car window auto lifter. A series of different concentrations of aqueous SPA solution were made up, cooling curves of these solutions at different temperatures were measured, and the cooling characteristics of the quenchant were evaluated according to the requirements for high strength steel wire patenting treatment. The cooling mechanism of patenting treatment and the cooling behavior of steel wires in the different concentrations of SPA solution bath at different temperatures were systematically explored and analyzed. Then, the cold-drawn KSC72A (0.72 % carbon) steel wires were subjected to patenting treatment in the optimized concentration of the SPA solution bath. The effect of the staying time in the water bath treatment on the microstructure and mechanical properties of the steel wire was investigated by means of a scanning electron microscope, a transmission electronic microscope, and material testing machines. The results show that when the SPA solution concentration is between 5–20 %, both the cooling rate at the high temperature range and the vapor blanket breaking the temperature decrease with the bath temperature increasing. When the temperature of the SPA aqueous solution bath is between 70°C∼95°C, the concentration has a barely significant effect on the cooling rate at a higher temperature range, which is needed for the sorbite transformation; however, the higher bath temperatures can make the vapor blanket stage (A-stage) maintain at 400°C. The patenting test results show that, within the designed length of the patenting bed, both the sorbite colony size and the lamella space decrease with the extension of processing time in the solution bath, and the mechanical properties (tensile strength, percentage of elongation, and reduction of area) of the steel wires do increase as the sorbite colony size and the lamella space decrease. When the KSC72A (0.72 % carbon) steel rope wires with diameters of 0.8 mm are subjected to the patenting treatment in the SPA solution bath at 90°C with the concentration of 10 %, the satisfactory metallurgical results and mechanical properties can be obtained by using a wire feed speed of 50 cm/min within the 50-cm length of the solution bath. The sorbite lamellae space and the sorbite colony size of the steel rope wires are about 82.76 nm and 2.86 μm, respectively. The tensile strength, elongation percentage, area reduction, and micro-hardness reach 1,266 MPa, 6.4 %, 54.5 %, and 340 HV, correspondingly. This excellent combination of the mechanical properties completely meets the technical requirements of the high strength steel rope wire. Hence, the SPA aqueous solution bath can replace the traditional lead bath to be used for the patenting process of high strength steel rope wires.

Effect of Solution pH and Post-annealing temperatures on the Optical Bandgap of the Copper Oxide Thin Films Grown by modified SILAR Method

AbstractCuprous oxide (Cu2O) thin films have been grown on both soda lime glass (SLG) microscope slides and Fluorine-doped Tin Oxide (FTO) substrates by a modified SILAR technique. The pH level of the bath solution was systematically varied in the range of 4.50 – 7.95 to elucidate their effect on the physical properties of the deposited product. The prepared films showed compact surface morphology composed of spherical grains evident from their SEM images. The XRD measurement showed that the as-deposited films were single phase Cu2O with (111) preferred orientation and this texturing was found to be increasing with increasing pH and annealing temperature. The annealed Cu2O films were found to be stable up to 200 °C and completely converted to cupric oxide (CuO) phases when the temperature reached to 350 °C. The estimated optical bandgaps of the as-grown samples were found in the range of 2.28 – 2.48 eV using UV-Vis-NIR transmission data and showing a bandgap narrowing trend with the decreasing level of solution pH. The effect of post-annealing temperatures (75-350 0C) on the as-deposited films was also studied and found to be crucial to control the optical bandgap (1.44 – 2.13) eV and electrical properties of the films. The sheet resistance of the as-deposited samples was found to be decreasing from 4120 MΩ/square to 800 MΩ/square while grown with increasing acetic acid content in the precursor solutions and decreasing up to 2.66 MΩ/square while annealing up to 250 °C in the air.

Fabrication of MoS2/WSe2 heterostructures as electrocatalyst for enhanced hydrogen evolution reaction

Two-dimensional material based heterostructures produce novel phenomena due to distinctive interactions between stacked layers. This paper details fabrication of van der Waals heterostructure consisting of layered MoS2 and WSe2 on FTO substrates by combining solution bath and radio-frequency sputtering. Raman scattering confirmed WSe2/MoS2 heterostructure formation, X-ray photoelectron spectroscopy surface profile detailed the heterostructure composition, and depth profile showed heterostructure interfacial structure with stacked WSe2 and MoS2 layers on the FTO substrate. Surface properties confirmed the WSe2/MoS2 heterostructure formed a multi-structured array of nanograins, and high resolution electron micrographs confirmed vertically formed layered fringes. Hydrogen evolution showed enhanced electrocatalytic behavior with 116 mV overpotential at 10 mA/cm2 and 76 mV/decade Tafel slope. Electrocatalytic property robustness was confirmed by over 20 h continuous hydrogen evolution reaction in an acidic solution. Enhanced electrocatalytic outcomes were due to increased interfacial hole-electron separation, dispersing active facets through the interface. The stacked layered structure provides a new avenue for two-dimensional heterostructures for energy harvesting devices.

Effect of Additives on Electrodeposition of Zinc-Nickel Alloy On Mild Steel

Considering the good corrosion resistance of Zn-Ni alloy, it is selected in the present study to be the protective coating on mild steel and it is considered as a strong candidate for the replacement of environmentally hazardous cadmium. Zn-Ni alloy coating is applied by electrodeposition at optimum temperature, current density and time. The bath solution used is consisting of EDTA as complexing agent. The electrodeposition is also carried out with tartaric acid and benzaldehyde additives to have good corrosion resistance and brightness. The electrodeposits obtained with and without additives are examined for nature and alloy composition. The corrosion behaviour of the electrodeposits is studied by Tafel polarization and electrochemical impedance spectroscopy.

Facile and cost-effective growth of MoS2 on 3D porous graphene-coated Ni foam for robust and stable hydrogen evolution reaction

To replace the costly, noble platinum electrocatalyst, the inexpensive, earth abundant and highly efficient electrocatalysts of layered transition metal dichalcogenides (TMDs) are explored for the hydrogen evolution reaction (HER). This paper describes cost-effective synthesis of 1T-MoS2 on 3D-graphene/Ni foam (NF) via a facile solution bath approach as an electrocatalyst for HER. The improved HER performances were observed due to the 3D-structure of MoS2/graphene. HER performance of MoS2/graphene/NF electrocatalyst exposed a superior catalytic performance with the low overpotential (−89 mV vs RHE) to drive the 10 mA cm−2, steep Tafel slope (45 mV dec−1), large exchange current density (4.16 × 10−1 mA cm−2), and robust stability over 18 h. Density functional theory (DFT) calculations also confirmed the reduced Gibbs free energy for H-adsorption (ΔGH) for MoS2/graphene compared to MoS2. The observed results suggest that the 1T-MoS2/graphene/NF is an interesting alternative to platinum-based catalyst for boosting HER efficiency.

Achieving non-adsorptive anodized film on Al-2024 alloy: Surface and electrochemical corrosion investigation

Naturally formed oxide film on the surface of aluminum reduces corrosion rate to significant extent. Anodizing of aluminum is done to enhance this feature by increasing film thickness deliberately to desired level. In the current work, anodizing of Al-2024 alloy was carried out in sulfuric-acetic acid anodizing bath of different concentrations along with gradually increased applied potential. The structure and morphology of the developed anodized film was investigated with and without the addition of acetic acid. Structural and surface analysis results revealed the difference in the anodized layer formation with the presence of acetic acid in sulfuric acid bath. Electrochemical investigation was carried out to evaluate the surface protective performance of the formed anodized film in 3.5% NaCl solution. Potentiodynamic polarization (PDP) and electrochemical impedance spectroscopy (EIS) revealed that lowest corrosion rate with highest polarization resistance was achieved due to the presence of CH3COOH in the anodizing bath. Non-adsorptive and less porous anodized film noticed to be formed with the presence of CH3COOH in bath solution.

An accurate and sensitive analytical strategy for the determination of palladium in aqueous samples: slotted quartz tube flame atomic absorption spectrometry with switchable liquid-liquid microextraction after preconcentration using a Schiff base ligand.

This study presents a green analytical method for palladium determination by slotted quartz tube flame atomic absorption spectrometry (SQT-FAAS) following switchable liquid-liquid microextraction (SLLME). Efficient extraction of palladium was facilitated by complexation with a Schiff base ligand, synthesized specifically for this study. A three-stage thorough optimization procedure was carried out to boost the absorbance output of palladium. Complex formation was the first stage, and parameters evaluated included buffer solution pH and amount, concentration of ligand, and mixing period. The amount of switchable solvent and concentration and amount of sodium hydroxide and acid amount were optimized in the second stage. Optimization of sample and fuel flow rates and SQT parameters completed the third stage of optimization, and all optimum parameters were used to determine analytical performance of the method. The method had a broad linear dynamic range, and the calibration plots showed good linearity with R2 values greater than 0.9991. The limits of detection and quantification of the SLLME-SQT-FAAS method were 15 and 50μg/L, respectively. The precision of the method, expressed as percent relative standard deviation, was below 9.0% for all measurements. Spiked recovery results performed for a palladium electroplating bath solution gave poor results when quantified against aqueous calibration standards. Matrix matching was therefore used to improve recovery results which ranged between 97 and 105% for four different spike concentrations.

Biophysical Properties of the Electropermeabilization-Induced Membrane Conductance in Patch Clamped Adrenal Chromaffin Cells

Our group recently showed that a single 5 ns high intensity electric pulse (NEP) elicited membrane permeabilization in whole-cell voltage clamped bovine adrenal chromaffin cells, inducing an instantaneous inward conductance at the holding potential of −70 mV. When Na+ was completely replaced in the bath solution with n-methyl-d-glucamine, the NEP-induced current was significantly reduced suggesting that the current was partially carried by Na+. Later, a slow voltage ramp protocol from −100 mV to 80 mV was used to inactivate Na+ channel, whereas K+ and Ca2+ channels were blocked by cesium, tetraethylammonium and nitrendipine. With this ramp protocol, the fact that the NEP-induced conductance showed a consistent reversal potential around −10 mV revealed the properties of the current that resembled protein ion channel-like activity. We further exposed cells to SKF-96365 and La3+, both compounds considered to be able to alter the activity of TRP channels. The results showed 33% and 59 % inhibition effect on the NEP-induced current. Therefore, one possibility of the NEP-induced conductance is a TRP-like channel that is activated via some sort of elctromechnical coupling triggered as a consequence of the NEP. It is known that many TRP channels are localized in caveolae, a subset of membrane lipid rafts involved in compartmentalized signal transduction. Methy-β-cyclodextrin, as cholesterol depletion drug which disrupts caveolae integrity, produced a strong inhibitory effect on the NEP-induced current suggesting the hypothesis that caveolae disruption altered TRP trafficking and/or compartmentalization leading to a diminished ability of NEP to activate these channels, although this observation cannot rule out the possibility that membrane cholesterol depletion altered the biophysical properties of the membrane in a way that would prevent or limit the formation of lipid-containing electronanopores.

Catalytic effect of ammonia-containing species on water splitting during electrodialysis with ion-exchange membranes

It is known that some components of the bathing solution can enhance water splitting at depleted solution/ion-exchange membrane interface via protonation/deprotonation reactions with water. In this paper, we show that not only the presence of such components is important, but also a mechanism ensuring their sufficiently high concentration near the membrane surface. A comparative study of the electrochemical behavior of a Neosepta® homogeneous cation-exchange CMX and an anion-exchange AMX membranes (Astom, Japan) in 0.02 M KCl or 0.02 M NH4Cl solutions is carried out. The NH4+/NH3 couple is an effective catalyst of water splitting. The deprotonation reaction rate constant of the NH4+ ions, which limits the rate of water splitting, is about 10 s−1. It is almost 6 orders of magnitude greater than the rate constant for direct water dissociation in free solution. A comprehensive electrochemical characterization of the membrane systems is made: voltammetry, chronopotentiometry, electrochemical impedancemetry, and pH-metry (including color indication of the pH of the membrane internal solution). It is found that the water splitting rate at the interface of the AMX membrane in the NH4Cl solution is essentially higher than in the KCl solution. The difference in the rates of this reaction in KCl and NH4Cl solutions at the CMX membrane is insignificant. The reason for the weak effect of the NH4+/NH3 couple on the rate of water splitting at the CMX membrane is that the concentration of both NH4+ and NH3 species is very low near its surface if the current density is close to or higher than its limiting value. As for the AMX membrane, we show that the ammonia-containing species can be transported to its depleted surface from the enriched solution by back “facilitated” diffusion through the membrane and this transport plays a crucial role in the occurrence of the rapid water splitting.

Cyclosis-mediated intercellular transmission of photosynthetic metabolites in Chara revealed with chlorophyll microfluorometry.

Symplastic interconnections of plant cells via perforations in adjoining cell walls (plasmodesmata) enable long-distance transport of photoassimilates and signaling substances required for growth and development. The pathways and features of intercellular movement of assimilates are often examined with fluorescent tracers whose molecular dimensions are similar to natural metabolites produced in photosynthesis. Chlorophyll fluorescence was recently found to be a sensitive noninvasive indicator of long-distance intracellular transport of physiologically produced photometabolites in characean internodes. The present work shows that the chlorophyll microfluorometry has a potential for studying the cell-to-cell transport of reducing substances released by local illumination of one internode and detected as the fluorescence increase in the neighbor internode. The method provides temporal resolution in the time frame of seconds and can be used to evaluate permeability of plasmodesmata to natural components released by illuminated chloroplasts. The results show that approximately one third of the amount of photometabolites released into the streaming cytoplasm during a 30-s pulse of local light permeates across the nodal complex with the characteristic time of ~10s. The intercellular transport was highly sensitive to moderate elevations of osmolarity in the bath solution (150mM sorbitol), which contrasts to the view that only transnodal gradients in osmolarity (and internal hydrostatic pressure) have an appreciable influence on plasmodesmal conductance. The inhibition of cell-to-cell transport was reversible and specific; the sorbitol addition had no influence on photosynthetic electron transport and the velocity of cytoplasmic streaming. The conductance of transcellular pores increased in the presence of the actin inhibitor cytochalasin D but the cell-to-cell transport was eventually suppressed due to the deceleration and cessation of cytoplasmic streaming. The results show that the permeability of plasmodesmata to low-molecular photometabolites is subject to upregulation and downregulation.

Hydrogen peroxide constricts rat arteries by activating Na+-permeable and Ca2+-permeable cation channels

Oxidative stress is associated with many cardiovascular diseases, such as hypertension and arteriosclerosis. Oxidative stress reportedly activates the L-type voltage-gated calcium channel (VDCCL) and elevates [Ca2+]i in many cells. However, how oxidative stress activates VDCCL under clinical setting and the consequence for arteries are unclear. Here, we examined the hypothesis that hydrogen peroxide (H2O2) regulates membrane potential (Em) by altering Na+ influx through cation channels, which consequently activates VDCCL to induce vasoconstriction in rat mesenteric arteries. To measure the tone of the endothelium-denuded arteries, a conventional isometric organ chamber was used. Membrane currents and Em were recorded by the patch-clamp technique. [Ca2+]i and [Na+]i were measured with microfluorometry using Fura2-AM and SBFI-AM, respectively. We found that H2O2 (10 and 100 µM) increased arterial contraction, and nifedipine blocked the effects of H2O2 on isometric contraction. H2O2 increased [Ca2+]i as well as [Na+]i, and depolarised Em. Gd3+ (1 µM) blocked all these H2O2-induced effects including Em depolarisation and increases in [Ca2+]i and [Na+]i. Although both nifedipine (30 nM) and low Na+ bath solution completely prevented the H2O2-induced increase in [Na+], they only partly inhibited the H2O2-induced effects on [Ca2+]i and Em. Taken together, the results suggested that H2O2 constricts rat arteries by causing Em depolarisation and VDCCL activation through activating Gd3+-and nifedipine-sensitive, Na+-permeable channels as well as Gd3+-sensitive Ca2+-permeable cation channels. We suggest that unidentified Na+-permeable cation channels as well as Ca2+-permeable cation channels may function as important mediators for oxidative stress-induced vascular dysfunction.

Optical and Structural Properties of Chemical Bath Deposited Cadmium Sulphur Selenide (CdS1–xSex (0 ≤ x ≤ 1)) Thin Films

The tuneable band gap property of Cadmium-sulphur-selenide (CdS1–xSex) thin film makes it an appropriate material for a wide range of optoelec-tronic applications and this has aroused a lot of interest. In this paper, we report the study of Cadmium-sulphur-selenide (CdS1–xSex) thin films, successfully grown on commercial glass slide substrate by the chemical bath deposition technique. The effect of selenium content (x value) on the structural, and some optical properties have been studied. The bath solution contained cadmium acetate dehydrate [Cd(CH3COO)2·2H2O], so-dium selenosulphate [Na2SeSO3] and thiourea [CS(NH2)2] were used as the sources of Cd2+, Se2﹣ and S2+, respectively. Tartaric acid (C4H6O6) was used as a complexing agent. The pH of the solution was adjusted to 12 by drop-wise addition of ammonia. The bath temperature was kept at 90°C for a deposition time of 1 hour. Post deposition annealing processes of the thin films were performed in a furnace at a temperature of 400°C for two hours. Both as-deposited and annealed films were characterised by Powder X-Ray Diffraction, Scanning Electron Microscopy, UV-Visible Optical Absorption Spectroscopy and Energy Dispersive X-Ray Analysis. Optical absorption data analysis indicates that direct allowed transitions occur in the films. The band gap of the as-deposited CdS1–xSex decreased linearly from 2.34 eV to 1.48 eV, with increasing selenium content, and in the annealed samples, decreased from 1.84 eV to 1.36 eV. X-ray diffrac-tion measurements revealed, that pure CdS, and CdSe had mixed hexago-nal and cubic phases. All the remaining ternary compounds were com-posed of cubic CdS and hexagonal CdSe phases. The annealed samples showed well defined and more intense peaks, suggesting an improvement in crystallinity. The average grain size increased slightly with increasing selenium content. SEM micrographs showed that the films were compact with a smooth texture and good coverage across the entire area of the substrate.

Patch-Clamp Analysis of the Mitochondrial Calcium Uniporter.

Mitochondria accumulate significant amounts of calcium when cytosolic calcium is elevated above the resting levels of 50-100nM during signaling events. This calcium uptake is primarily mediated by a macromolecular protein assembly called mitochondrial calcium uniporter (MCU) that resides in the mitochondrial inner membrane. In 2004, we applied patch-clamp technique for the first time to record calcium currents from the mitochondrial inner membrane and proved unequivocally that MCU is a highly selective calcium channel. This chapter describes how patch-clamp technique can be applied to record the Ca2+ uniporter currents from the mitochondrial inner membrane, isolation of mitochondria from the heart tissue, and preparation of mitoplast using French Press. We also discuss advantages of patch-clamp technique as compared to other methods of determining mitochondrial uniporter activity and important considerations in applying patch-clamp technique to such a small subcellular organelle. With small variations in the bath and pipette solution composition, the same methodology can be applied to study any other currents (e.g., H+ or Cl-) from the mitochondrial inner membrane.

Growth of a Pure and Single Phase Iron Sulfide (Pyrite) Thin Film by Electrochemical Deposition for Photovoltaic Applications

Single phase iron pyrite (FeS2) films have been successfully deposited on ITO-coated glass substrates using a 3-electrode electrochemical system with graphite as the counter electrode and Ag/AgCl as the reference electrode. In this single-step electrodeposition, the FeS precursor thin film was directly electrodeposited on the conductive substrate from the electrolytic bath solution which contained FeSO4.7H2O as an iron source, and Na2S2O3.5H2O as a sulfur source. The deposition was carried out potentiostatically at a constant potential of -0.9 V vs. Ag/AgCl at room temperature. The growth of the iron pyrite phase was achieved by annealing the as-deposited at 500°C for an hour in an ambient of sulfur to form the pyrite phase. For sulfurization, two different techniques, one using the Kipp’s apparatus and a second, which involved heating elemental sulfur at 200°C, were used for the production of the sulfur gas. X-ray diffraction analyses of the sulfurized films showed that both sulfurization techniques appeared to form the pyrite phase, however, the second method yielded films with maximum crystalline order and stoichiometry with no discernable impurity peaks. Optical absorption measurements revealed the existence of a direct transition with an estimated band gap of 1.75 eV. SEM micrograph showed a compact morphology with a rough surface made up of crystallites of irregular shapes and sizes with well-defined edges, covering the entire substrate. EDAX analysis of the film was consistent with the formation of FeS2 pyrite thin films.