Aqueous Solution Of Citric Acid Research Articles

Morphological and Structural Modifications of Si-Based Nanostructures Synthesized from Metal Silicide Templates in IP6, Acid and Metal Chloride Solutions

Powders consisting of Si-based nanostructures were synthesized by the extraction of Ca atoms from CaSi2 powders using an inositol hexakisphosphate (IP6) aqueous solution. The raw CaSi2 powders were simply immersed in a diluted IP6 solution, then dried. It is noted that the Si-based nanostructures were easily exfoliated from the powders to expose the surfaces corresponding to the Si {111} planes of the nanostructures. In addition, the Si-based nanostructures were also synthesized by metal atom extraction from SrSi2, BaSi2 and Mg2Si using the IP6 aqueous solution. It was found that the nanostructures mainly including the amorphous Si-oxide phase were obtained for the IP6-treated SrSi2, BaSi2 and Mg2Si powders. Moreover, the amorphous Si oxide-based nanostructures were synthesized from CaSi2 using citric acid, malic acid, FeCl3 and FeCl2 aqueous solutions. It was demonstrated that the morphological and structural properties of the synthesized Si-based nanostructures depend on the silicide templates and the solutions.

Improved stability to auto-oxidation of the olive oil by addition of citric acid Short title: Olive oil auto-oxidation and citric acid

The effect of addition of citric acid on the oxidation stability of olive oil produced in North-East of Algeria was assessed using UV- Visible spectrophotometry (K232 nm, K270 nm, carotenoids (470 nm), chlorophylls (670 nm)), free acidity, peroxide value, Fourier Transform Infrared spectroscopy (FTIR) and chemometric methods. Five olive oils (Chemlal variety) were collected from five geographical areas. Two preparations were made for each geographical area: the first one by adding a small amount of citric acid aqueous solution 1/1000 in volume and the second preparation without any additive. All analyses were carried out every 30 days during one year. A higher oxidative stability of olive oil samples was reached when using 1/1000 of citric acid in comparison with samples without any additive through the values of quality analytical indices. FTIR has been used to evaluate auto-oxidation of olive oils. The frequency regions of 3474-2679 cm-1 and 1746-1032 cm-1 were picked up for olive oil storage time quantification. A close relationship between actual and predicted storage time shows a good correlation with R2 of 0.999, 0.989, 0.980, 0.984 and 0.983 for all samples. Thus, citric acid can enhance oxidative stability and improve the shelf life of olive oil.

Corrosion Rates of Stainless Steels in Renewable Biofuel Sources of Refined Rapeseed Oil, Waste Cooking Oil and Animal Waste Lard

The 1.4541 and the 1.4571 stainless steels and a carbon steel were subjected to immersion corrosion tests in stagnant and stirred biomass fuel sources such as rapeseed oil, waste cooking oil and animal waste lard as well as their emulsions with 5 and 50 wt.% aqueous citric acid solutions at a temperature of 80°C so as to model storage, handling and purification conditions. Passivation of carbon steel was facilitated by flow of the less acidic rapeseed and waste cooking oils and increased flux of oxygen. Carbon steel was sensitive for the higher concentration of proton donor species, acidity of the waste lard. Higher mass loss rates correlated with increased corrosion currents measured in citric acid solution by electrochemical methods. Flow of the biomasses and increased acid concentration of the emulsions were beneficial for the passivation of stainless steels. Although corrosion related mass loss, dissolution rate of the passive layers increased by flow and high acidity of the fluids, both the formation and compactness of passive layers are facilitated by the biomasses with higher concentration of oxygen donating species like water, alcohol and acids. Surface transformation of the passivating steels was reflected by decreasing electrochemical pseudo-capacity of the interfaces and increasing resistance of the passive layers derived from the results of Tafel and Stern methods as well as impedance results. Anti-correlation between mass loss results obtained by immersion in the biomasses and electrochemical data measured in dilute aqueous citric acid solution is explained by the varied compactness, resistance of the passive layers and exchange currents of the steel electrodes due to the orders of magnitude different activities of the hydrogen ion in the biomass mixtures and citric acid solution.

The Effect of Food‐Simulating Agents on the Bond Strength of Hard Chairside Reline Materials to Denture Base Resin

To investigate the influence of food-simulating agents on the shear bond strength between direct hard liners and denture base acrylic resin. In addition, mode of failure was evaluated. One hundred fifty cylindrical columns of denture base resin were fabricated and bonded to three types of hard reline materials (Hard GC Reline, Tokuyama Rebase II Fast, TDV Cold Liner Rebase). Specimens of each reline material were divided into five groups (n = 10) to undergo 12-day immersion in distilled water, 0.02 N citric acid aqueous solution, heptane, and 40% ethanol/water solution at 37°C. The control group was not immersed in any solution. The shear bond strength test was performed, and the failure mode was determined. Statistics were analyzed with two-way ANOVA and chi-square test (α = 0.05). Significant interaction was found between the hard liners and food simulating agents (p < 0.001). The shear bond strength of Tokuyama in 40% ethanol and TDV in heptane decreased significantly (p = 0.001, p < 0.001 respectively); however, none of the solutions could significantly affect the shear bond strength of Hard GC Reline (p = 0.208). The mixed failure mode occurred more frequently in Hard GC Reline compared with the other liners (p < 0.001) and was predominant in specimens with higher bond strength values (p = 0.012). Food simulating agents did not adversely affect the shear bond strength of Hard GC Reline; however, ethanol and heptane decreased the bond strength of Tokuyama and TDV, respectively. These findings may provide support to dentists to recommend restricted consumption of some foods and beverages for patients who have to use dentures relined with certain hard liners.

Enamel Remineralization Potential of Novel Dentifrice with Tetracalcium Phosphate/Monetite Powder Component

Abstract The aim was to investigate the enamel health benefits of a novel toothpaste with active tetracalcium phosphate/monetite mixtures under de/remineralization cycling. The enamel de/remineralization cycling protocol was consisted of demineralization in 1% aqueous solution of citric acid at pH 3.6 with following treatment with toothpastes and soaking in remineralization storage solution. Effectiveness of toothpastes to promote remineralization was evaluated by surface microhardness measurements, enamel erosion depth, analysis of surface roughness and fluorescent optical method. The novel tetracalcium phosphate/monetite toothpaste had the same remineralization potential as commercial calcium silicate/phosphate toothpaste and significantly higher than control storage solution group (p&lt;0.05). Surface roughness was significantly lower after addition of fluorides to dentifrice (p&lt;0.05). The enamel erosion depth was significantly reduced by applying toothpastes as compared to negative control (p&lt;0.05) and did not differ from calcium silicate/phosphate toothpaste (p&gt;0.66). The results showed that dentifrice formulations containing active tetracalcium phosphate/monetite mixture with or without fluoride addition had excellent enamel remineralization potential under de/remineralization cycling and successfully promote remineralization of enamel with daily using in the form of toothpaste.

Volumetric, Viscosity and Conductance Studies of Solute–Solute and Solute–Solvent Interactions of Some Alkali Metal Chlorides in Aqueous Citric Acid at Different Temperatures

Abstract The present study aims for the structure-making and structure-breaking behavior of some electrolytes in aqueous citric acid solution. The density, viscosity and conductance of some alkali metal chlorides lithium chloride (LiCl), sodium chloride (NaCl) and potassium chloride (KCl) in 0.01 m aqueous citric acid have been measured in the concentration range 0.01–0.12 m at 303.15, 308.15, 313.15 and 318.15 K. From these measurements, molar volume, viscosity parameters and molar conductance have been deliberated. Debye Hückel limiting law is used for the assessment of the contributions of various types of solute–solvent interactions. Jones–Dole viscosity equation is used to calculate viscosity B-coefficient for these salts in aqueous citric acid, which is known to provide information concerning the solvation of ions and their effects on the structure of the solvent in the near environment of the solute particles. The free energies of activation of viscous flow per mole of solvent, Δ μ 1 0 ‡ $\Delta \mu _1^{0\ddagger }$ and solute, Δ μ 2 0 ‡ , $\Delta \mu _2^{0\ddagger },$ have also been evaluated by using viscosity data. Using molar volume, the transfer volume Фv o tr has also been computed. The structure making/ breaking behavior of LiCl, NaCl and KCl is inferred from the sign of second derivative of partial molar volume with respect to temperature at constant pressure (d2φv o/dT2)p, Temperature coefficient of B. dB/dT and temperature coefficient of Walden product i.e. d(Λm oηo)/dT values. It has been found from these studies that LiCl, NaCl and KCl behave as structure-breaker in 0.01 m aqueous citric acid solution. The results have been qualitatively used to explain the molecular interaction and structural changes between the components of these mixtures.

One-step synthesis of fluorescent carbon dots for sensitive and selective detection of hyperin

In this article, we presented a new rapid, sensitive and selective method for the determination of hyperin (Hyp) based on the fluorescence quenching of fluorescent carbon dots (CDs). The CDs were prepared by simply mixing an aqueous solution of citric acid with diphosphorus pentoxide. This one-step synthetic route is fast and simple with neither high temperature nor complicated synthesis steps is involved. When Hyp was added to CDs solution, the fluorescence intensity of the CDs significantly decreased. The CDs display high selectivity for Hyp over many potentially interfering substances. Under the optimized conditions, a good linear relationship between the fluorescence intensity ratio Fo/F and the concentration of Hyp is obtained in a range of 0.22–55 µM with a detection limit (S/N = 3) of 78.3 nM. The method was successfully applied for the determination of Hyp in fufangmuji granules and human serum samples with recoveries in a range of 93.3–107.0%. This paper highlights the usefulness of CDs as an effective fluorescence probe for the Hyp detection due to its easy preparation, low-cost, excellent photostability, favorable biocompatibility and low cytotoxicity.

Improvement of the Electrochemical Performance of P2-Na0.7MnO2 Composite By Ni Doping

Lately, sodium ion batteries (SIB) have been studied very intensively as a potential alternative to Li ion batteries (LIB). As sodium is 6th most abundant element in Earth which makes it very cheap compared to lithium. Also, the cell chemistry is similar to LIB system. In addition, cheap and lighter aluminum can be used as a current collector at the anode side instead of copper foil. Among the studied cathodes, P2-type Na0.7MnO2 cathode is more attractive as it can deliver high capacity and high energy density, moreover Mn is one of the cheap elements. However, the long cyclability of the composite has been an issue due to the Jahn-Teller distortion which is associated with the existence of Mn3+. In this study, our approach was to suppress the Jahn-Teller distortion by Ni doping by varying the dopant amount from 0%, 10% and 20%. The composites were synthesized by combustion method. The aqueous solution of stoichiometric values of sodium nitrate (98%), manganese (II) nitrate hexahydrate (97%), and nickel (II) nitrate hexahydrate (98%) were added to aqueous citric acid solution (nitrates : citric acid, 1 : 0.5 in weight). The solution was heated on a hot plate at 100 °C for overnight under constant stirring to evaporate the solvent. Then dried powder was further heated to 200 °C for auto combustion of citric acid. Burnt powder further heated at 500 °C for 3 h to decompose the nitrates and yield a homogeneously mixed amorphous powder containing carbon residues. The obtained decomposition product was pelletized and heated in a tube furnace at 900 °C (heating rate – 5 °C / min) for 10 h in air atmosphere and then slowly cooled to room temperature. The obtained powder was transferred to Ar-filled glove box to avoid the contact with moisture in the air. X-ray diffraction (XRD, Xpert, PANalitical) using Cu-Kα radiation was employed to characterize the crystal structure of the synthesized powders. XRD measurement was carried out in the 2θ range of 10−80° with a step size of 0.03°. The FULLPROF Rietveld program was used to analyze the observed powder diffraction patterns. Structural studies during cycle were examined by means of in-situ synchrotron X-ray diffraction (XRD) and ex-situ X-ray Absorption Spectroscopy (XAS). In-situ XRD and ex-situ XAS measurement was respectively carried out at 9B beamline and 8C beamline of Pohang Accelerator Laboratory (PAL), Pohang, South Korea. Electrochemical properties were studied in an half-cell configuration assembling a R2032 coin-type cell using sodium metal as the negative electrode in an Ar-filled glove box. The electrolyte solution comprised 0.5 M NaPF6 in propylene carbonate and fluorinated ethylene carbonate (PC:FEC, 98:2 in volume). The cells were charged and discharged between 2.0 V and 4.3 V at a rate of 0.1C at 25 °C. Among the successfully synthesized samples Na0.7Mn0.8Ni0.2O2 composite displayed better electrochemical performance. As shown in Figure 1 the composite delivered initial discharge capacity of 160 mAh g-1 at 0.1C between voltage of 2.0 V and 4.3 V and the capacity retention is remarkably improved compared to bare composite. Data on structural change during cycling and other detailed studies will be presented at the meeting. Figure 1. Initial charge-discharge profiles of P2-Na0.7Mn1-xNixO2 composites at 0.1C. Figure 1

Aqueous electrophoretic deposition of citric-acid-stabilized copper nanoparticles

Citric-acid-stabilized copper (Cu) nanoparticles (NPs) were deposited on indium tin oxide (ITO) substrates using aqueous electrophoretic deposition (EPD). Usually, Cu NPs are unstable in aqueous solution because they oxidize and aggregate easily, which is why aqueous EPD has not been used before to deposit them on substrates. However, we showed that treating Cu NPs using citric acid in aqueous solution removed surface oxides and stabilized the surfaces sufficiently. After the treatment, the Cu NPs remained highly stable in aqueous solution even after one week, and this stability was sustained under an electric field in aqueous solution. The Cu NPs were deposited rapidly on ITO substrates by aqueous EPD at a deposition rate that increased with current density (0.25, 0.46, and 0.96 mg/cm2/min at 0.10, 0.20, and 0.30 mA/cm2, respectively). The Cu NP films obtained by the rapid deposition at 0.30 mA/cm2 contained too much water, leading to cracked and low density films. Instead, we demonstrated that a current density of 0.20 mA/cm2 resulted in uniform and high density Cu NP films.

A facile environmentally benign strategy to synthesize Bi3+ self-doped NaBiO3·2H2O with enhanced visible light photocatalytic performance

A facile environmentally benign strategy was developed to prepare Bi3+ self-doped NaBiO3·2H2O by acidic hydrolysis of NaBiO3·2H2O in citric acid aqueous solution. The investigation of methyl orange degradation performance revealed that Bi3+ self-doped NaBiO3·2H2O exhibited remarkably enhanced visible light photocatalytic activity than pristine NaBiO3·2H2O, and the optimal Bi3+ self-doped NaBiO3·2H2O (CBO-0.25) achieved the maxima (92.5%) degradation efficiency within 30 min. Due to the formation of new energy level derived from Bi3+ in the forbidden gap, Bi3+ self-doped NaBiO3·2H2O samples presented extended visible light response range and improved photogenerated charges separation efficiency than pristine NaBiO3·2H2O, which is responsible for the enhancement of photocatalytic performance. Radical capture experimental results confirmed that hole was the dominant reactive species. Our synthesis method for Bi3+ self-doped NaBiO3·2H2O may pave a new way for designing self-doped materials.

Thermogravimetric study of the reduction of CuO–WO3 oxide mixtures in the entire range of molar ratios

The oxide mixtures CuO–WO3 of various compositions were synthesized by citrate–gel combustion process, starting with the aqueous solutions of copper nitrate, ammonium tungstate and citric acid. Cu–W nanocomposite powders were produced by reduction of oxide mixtures in hydrogen atmosphere under thermogravimetric control. Characterization of CuO–WO3 mixtures and their reduction products was performed by SEM and XRD methods. The morphology of both oxide and metal particles displayed notable dependence on composition. Copper displayed promoting action during reduction of CuO–WO3 mixtures. The mean reduction temperature shifted monotonously from that of CuO toward that of WO3. The reduction proceeded in three steps, first of which was mainly reduction of CuO and the other two originated mainly of the two-step reduction of WO3. The composition CuO–WO3 at a molar ratio 1:1 was shown to form the compound CuWO4. The reduction of this compound was subjected to a detailed thermokinetic study. For those purposes, model-free expanded Friedman, multiple heating rate Coats–Redfern and Kissinger methods and some model-fitting methods, incorporated in the software Kinetics2015, were used. Among model-fitting models, the nucleation and growth kinetic model enabled the best fit of experimental results for all three reduction stages.

Molecular Interactions Investigation of L-Histidine in Water and in Aqueous Citric Acid at Different Temperatures Using Volumetric and Acoustic Methods

Abstract Densities, ρ and ultrasonic speeds, u of L-histidine (0.02–0.12 mol·kg−1) in water and 0.1 mol·kg−1 aqueous citric acid solutions were measured over the temperature range (298.15–313.15) K with interval of 5 K at atmospheric pressure. From these experimental data apparent molar volume Φ V , limiting apparent molar volume Φ V O and the slope SV , partial molar expansibilities Φ E O , Hepler’s constant, adiabatic compressibility β, transfer volume Φ V, tr O , intermolecular free length (Lf ), specific acoustic impedance (Z) and molar compressibility (W) were calculated. The results are interpreted in terms of solute–solute and solute–solvent interactions in these systems. It has also been observed that L-histidine act as structure maker in water and aqueous citric acid.

Investigation of the separation of carboxylic acids from aqueous solutions using a pilot scale membrane unit

Separation of carboxylic acids from aqueous solutions using synthetic membranes has been investigated within the context of this study. Formic, glycolic, malic, and citric acid aqueous solutions were prepared in the experiments as mixtures to be separated. Nanofiltration (NF) and reverse osmosis (RO) membranes were used for the separation of acid solutions. The experiments were carried out on a pilot scale membrane unit allowing the use of membranes with a surface area of 140cm2. Experiments were performed by using different initial acid concentrations (5–15% w.) at 10, 20, 30bar and 20°C. Thus, the effects of pressure, the type of membrane and acids were analyzed on the separation performance by using single acid solutions, and model equations were formed with the help of response surface methodology (RSM) in the case of citric acid, which has the highest rejection ratio. As a result of the experimental studies carried out, very high rejection values (max. 98.36%) were obtained and it was seen that the carboxylic acids were successfully separated from the aqueous media.

Nanocrystalline LiCo0.8Fe0.2PO4 / Multi-Walled Carbon Nanotubes Positive Electrode for 5-Volts Class Lithium Ion Batteries

1. Introduction Lithium cobalt phosphate (LiCoPO4) with olivine structure has attracted much attention as a new positive electrode material for lithium ion batteries because of its high potential (4.8V vs. Li/Li+), theoretical capacity (167 mAh g-1) and thermal stability due to the P-O covalent bonding. However, the practical use of LiCoPO4 has been limited by the capacity fading during cycling due to the electrolyte oxidation and irreversible structure changes such as amorphization and anti-site defects of the material during charge and discharge1). Besides, it suffers from its poor rate performance related to the inherently low electron conductivity (<10-9 S cm-1)2) and Li+ diffusivity (<10-13 cm2 s-1)2) due to its b-axis oriented diffusion path. To overcome these limitations, we have synthesized Fe-substituted LiCoPO4 (LiCo0.8Fe0.2PO4) nanoparticles which are highly dispersed within a multi-walled carbon nanotube (MWCNT) matrix via an original in-situ material synthesis method called ultracentrifugation (UC) treatment3,4). Here, we also report about the influence of Fe substitution on cycle and rate performances of LiCo0.8Fe0.2PO4. 2. Experimental UC treatment was carried out on the prepared mixture of Co(CH3COO)2・4H2O, Fe(CH3COO)2, CH3COOLi, citric acid, MWCNT and H3PO4 aqueous solution. Obtained composites were electrochemically characterized using a 2032 coin half-cell with Li metal in 1M LiPF6 / EC:PC:DMC (1:1:3, volume ratio). Physicochemical characterizations of the LiCo0.8Fe0.2PO4/ MWCNT composite were conducted by HRTEM, XRD, XPS, XAFS measurements and Mössbauer spectroscopy. 3. Results and Discussion The XRD pattern of LiCo0.8Fe0.2PO4 / MWCNT composite indicates an olivine structure, without impurity phases. The combination of XRD, XPS, XAFS and Mössbauer analysis suggests that substituted Fe3+ into LiCoPO4 crystals was not placed in the Co2+ site, but in the Li+ site. The result of HRTEM observation indicates that LiCo0.8Fe0.2PO4 nanocrystals (ca. 100 nm) were highly dispersed within a MWCNT matrix. In addition, HRTEM images of LiCo0.8Fe0.2PO4 / MWCNT composite showed that a substitution of Fe3+ into LiCoPO4 crystals prevents degradations such as amorphization of LiCoPO4and electrolyte decomposition during charge and discharge processes. Then, LiCo0.8Fe0.2PO4 / MWCNT composite showed a higher discharge capacity of 130 mAh g-1 than LiCoPO4 / MWCNT composite and enabled a 100C (36 seconds) rate discharge with 45 mAh g-1. Furthermore, the obtained composite showed stable cycle performance with 81 % of capacity retention after 100 cycles at 0.2C. These enhancements were achieved by the combination of an entanglement between nanocrystalline LiCo0.8Fe0.2PO4 and MWCNT matrix and Fe3+ substitution in the Li+ site of LiCoPO4. The Fe3+substitution gives a “pillar effect” which effectively prevents an irreversible crystal structure change and electrolyte decomposition during charge and discharge processes, resulting in the stable cycle performance. References 1) A. Boulineau et al., Chem. Mater., 27, 802 (2015). 2) S. Brutti et al., ACS Symposium Series, (2013). 3) K. Naoi et al., Acc. Chem. Res., 46, 1075 (2013). 4) K. Naoi et al., Energy Environ. Sci., 5, 9363 (2012).

Molecular interaction studies of l-alanine and l-phenylalanine in water and in aqueous citric acid at different temperatures using volumetric, viscosity and ultrasonic methods

Densities, ultrasonic speeds and viscosities of l-alanine and l-phenylalanine in water and in 0.1mol·kg−1 aqueous citric acid solutions were measured over the temperature range (298.15 to 313.15)K with interval of 5K at atmospheric pressure. From these experimental data apparent molar volume, limiting apparent molar volume and the slope, partial molar expansibilities, adiabatic compressibility, transfer volume, Falkenhagen coefficient, Jone-Dole's coefficient, the temperature derivative of Jone-Dole's coefficient, intermolecular free length, specific acoustic impedance, and molar compressibility were calculated. The results are interpreted in terms of solute – solute and solute-solvent interactions in these systems. It has also been observed that l-alanine acts as a structure breaker whereas l-phenylalanine acts as a structure maker in aqueous citric acid.

Fabrication of resistively-coupled single-electron device using an array of gold nanoparticles

We demonstrated one type of single-electron device that exhibited electrical characteristics similar to those of resistively-coupled SE transistor (R-SET) at 77 K and room temperature (287 K). Three Au electrodes on an oxidized Si chip served as drain, source, and gate electrodes were formed using electron-beam lithography and evaporation techniques. A narrow (70-nm-wide) gate electrode was patterned using thermal evaporation, whereas wide (800-nm-wide) drain and source electrodes were made using shadow evaporation. Subsequently, aqueous solution of citric acid and 15-nm-diameter gold nanoparticles (Au NPs) and toluene solution of 3-nm-diameter Au NPs chemisorbed via decanethiol were dropped on the chip to make the connections between the electrodes. Current–voltage characteristics between the drain and source electrodes exhibited Coulomb blockade (CB) at both 77 and 287 K. Dependence of the CB region on the gate voltage was similar to that of an R-SET. Simulation results of the model based on the scanning electron microscopy image of the device could reproduce the characteristics like the R-SET.

Evaluation of the activity of a gold catalyst supported on alumina (Au/γ–Al2O3)

The activity and selectivity of a catalyst (Au/γ–Al2O3) and the support (γ–Al2O3 cubic) in the oxidation reaction of cyclohexene in the liquid phase to obtain (epoxycyclohexane, 2-cyclohexen-1-ona, 2-cyclohexen-1-ol) were evaluated. The catalyst was prepared by the precipitation-deposition method from aqueous solutions of HAuCl4, citric acid (2% m/v) and polyvinyl alcohol. For the adequacy of the support, starting from boehmite calcined at 773 K, γ–Al2O3 phase was obtained. The reaction products and the evaluation of the same were analyzed by gas chromatograph (GC), showing relevant results of the Au/γ–Al2O3 system with high conversion levels, mostly to products of 2-cyclohexen-1-one, 2-cyclohexen-1-ol with 31.17% and 25.89% selectivity respectively, and to a lesser proportion to epoxycyclohexane with 13.33% selectivity. Regarding to the system formed by the support, the results reported were 13.31% for 2-cyclohexen-1-ona, 4.28% for 2-cyclohexen-1-ol and 3-23% epoxycyclohexane.

Study of InSb thin films grown on different substrates by the pulsed electrodeposition technique

Stoichiometric InSb thin films were prepared, on four different substrates, using a pulsed electrodeposition technique. The electrochemical bath used for the growth of InSb thin films was made up of a mixture of aqueous solutions of indium trichloride (InCl3), antimony trichloride (SbCl3), citric acid (C6H8O7·H2O) and sodium citrate (Na3C6H5O7·2H2O). Energy dispersive analysis of X rays along with X-ray diffraction (XRD) studies show that the elemental composition and crystalinity of thin films is strongly dependent on the ionic composition of the electrochemical bath. Stoichiometric InSb thin films can be grown on all the four substrates from the same bath, by properly selecting the composition of the bath. XRD studies show that the InSb thin films grown on all the four substrates have preferred orientation along the (111) plane. The presence of sharp Raman peaks of longitudinal optical phonon mode and transverse optical phonon mode in stoichiometric thin films confirm that they are of good crystalinity.

Effects of prewash on the pyrolysis kinetics of cut tobacco

ABSTRACTSmoking is a big public health issue because of the harmful substances generated. To diminish the risk of smoking, cut tobacco was washed with pure water, aqueous solution of sodium carbonate, or citric acid to remove the precursors of harmful substances in this work. The composition and pyrolysis kinetics of washed cut tobacco were determined to interpret the reduction in harmful substances generated during fast pyrolysis process. Sugar and alkaloid in cut tobacco were removed partly during prewash process. Thermogravimetric analysis demonstrated that cut tobacco washed with aqueous solution of citric acid was pyrolyzed at higher temperature, while the one washed with the solution of sodium carbonate was pyrolyzed at lower temperature. The changes in composition and pyrolysis kinetics resulted in significant reduction in benzo[a]pyrene, phenol, and nitrosamine 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone generated during pyrolysis, demonstrating that wash of cut tobacco with suitable chemicals is a promising approach to reduce the harmful substances generated during smoking.

Volumetric, viscosity and ultrasonic studies of solute-solute and solute-solvent interactions of glycine and diglycine in water and in aqueous citric acid at different temperatures

Densities, ρ, ultrasonic speeds, u and viscosities, ƞ of glycine and diglycine in water and 0.1mol·kg−1 aqueous citric acid solutions were measured over the temperature range (298.15 to 313.15) K at the interval of 5K at atmospheric pressure. From these experimental data apparent molar volume ФV, limiting apparent molar volume ФVO and the slope SV, partial molar expansibilities ФEO, adiabatic compressibility β, transfer volume ФVOtr, Falkenhagen coefficient A, Jone- Dole coefficient B, the temperature derivative of B coefficient dB/dT, intermolecular free length (Lf), specific acoustic impedance (Z), and molar compressibility (W) were calculated. The results are interpreted in terms of solute–solute and solute-solvent interactions. It was observed that glycine and diglycine act as structure breakers in aqueous citric acid at different temperatures.