Concentration Of Organic Additives Research Articles

Moderate concentration of citric acid for the formation of LaMnO3 and LaCoO3 nano-perovskites

Stoichiometric LaMnO3 and LaCoO3 nanoparticles were synthesized via calcination of a dried solution, containing molar ratio of La(NO3)3·6H2O/[Mn(NO3)2·4H2O or Co(NO3)2·6H2O]=1 and citric acid as disperser at temperature range of 600–900 °C for 5 h. The role of organic additive concentration, which was 0.0, 1.0, 2.5 and 5 times of the total number of moles of the nitrate ions, was investigated on phase formation, morphology, extent of crystallization and particle size of the products. Products were characterized by X-ray diffraction (XRD), Fourier-transform infrared spectroscopy (FT-IR), scanning electron microscopy (SEM) and transmission electron microscopy (TEM) analysis. The tendency of lanthanum ion toward manganese cation was observed to be more than to cobalt cation for the formation of LaBO3 (B: Mn or Co) perovskite phase. A spongy product was formed on perovskite phase formation or in the presence of citric acid. A constructive or destructive effect was observed for the organic disperser on perovskite phase formation, which depended on mole of the citric acid.

New antireflection coatings on silicate glass, deposited from a silicon dioxide sol containing a nonionogenic surfactant and an oligoether based on ethylene oxide

Transparent nanoporous thin films with low refractive index (1.23–1.25) were produced on glass substrates by application of a formulation based on a silicon dioxide sol into which two organic compounds, an oligoether based on ethylene oxide and a nonionogenic surfactant, are introduced. It is shown that the antireflection capacity of the nanoporous coating can be substantially raised at comparatively low concentrations of silicon dioxide and organic additives in the sol by making higher the rate at which the formulation is applied to the substrate.

The effects of pH and polyethylene glycol on the Cr(III) solution chemistry and electrodeposition of chromium

The effects of pH and the organic additive, polyethylene glycol (PEG), on the trivalent chromium electroplating were investigated in view of the solution stability, electrochemical reactions and the properties of deposited layer. It was sought out that the concentration of chromic complexes in the chromic bath with formic acid was closely dependent on pH. The chromic complex formation in the bath, examined by theoretical calculation and UV–vis absorption measurement, was not affected by PEG addition. However, adsorbed PEG molecules on the cathode surface caused the hydrogen evolution rate to be retarded and the deposited coating morphology smooth, small cracks and nodular structure. The variations of solution acidity and organic additive concentration affected the complex formation, the cathodic reaction and the physical property of the deposit.

Freeze granulation: Powder processing for transparent alumina applications

Use of freeze granulated powders is successfully used as an industrially viable alternative to loose powder sintering for transparent polycrystalline alumina (PCA). Freeze granulation with narrow granule size distribution was realized after suspension condition optimization, with very good flowability and regular spherical shapes. The key factors are low viscosity slurries linked to the complex interactions between the organic processing additives and their interaction with dopant ions in solution. Real in-line transmittances (RITs) of 52% were achieved by pulsed electric current sintering (PECS) of dry pressed green bodies from doped granulated powders. This is the first example of a high RIT (>50%) alumina produced from simple dry pressing of a granulated powder. The results indicate that higher granule solid loads and lower organic additive concentrations give better RITs after PECS. Aging of the powder slurry before freeze granulation proves a crucial step for the optical performance of the final transparent PCA.

Synthesis of CaCO3 nanoparticles via citrate method and sequential preparation of CaO and Ca(OH)2 nanoparticles

AbstractCalcium carbonate nanoparticles were synthesized via so‐called sol–gel citrate method using calcium nitrate as precursor in presence of different concentration of citric acid, selected to be 0.0, 0.5, 1.25 and 2.5 times of the concentration of the precursor, on calcining at 600 °C for 5 h. Stable phase of the calcite is formed in presence of citric acid. The roles of organic additive concentration, calcination temperature and sonication on the particle size of the products were investigated. Calcium oxide nanoparticles were prepared by facial calcination of the resulted product at 900 °C for 5 h. Calcium hydroxide nanoparticles, however, were synthesized on sonication of the product for 20 min in water at room temperature. Samples were characterized by XRD and FT‐IR studies. Crystallite size of samples was calculated by XRD data and was measured by TEM analysis. The specific surface are (SSA) of samples was calculated by the XRD data and compared by the measured BET. (© 2012 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)

Influence of yeast extract and casein hydrolysate on callus multiplication and somatic embryogenesis of date palm ( Phoenix dactylifera L.)

Complex organic additives are known to improve growth and differentiation of in vitro plant cultures. The present investigation was conducted to determine the effect of various concentrations of yeast extract (YE) and casein hydrolysate (CH) on callus growth and somatic embryogenesis in date palm cultivar Nabout Saif. Callus induced from shoot tip explants was grown on callus multiplication medium supplemented with either YE or CH at 0.0, 0.1, 0.25, 0.5, and 1 g l −1. To induce somatic embryogenesis, callus was transferred to a hormone-free medium containing the corresponding concentration of additives. The results have shown that callus weight and the number of somatic embryos were directly proportional to increases in the concentration of organic additives tested. Callus growth was best achieved when 1 g l −1 of either YE or CH was added to the culture medium. At this concentration of YE, callus growth was double that of the control medium. On CH-containing media growth was 2.3 times that of the control. This indicates that CH is more effective in enhancing callus growth. However, YE was more effective in enhancing somatic embryogenesis. The data show that the best somatic embryo formation was obtained on either 1 g l −1 YE or 0.5 g l −1 CH which produced 45 and 30 embryos per culture, respectively, as compared to 20 embryos produced in the control treatment. Resultant somatic embryos successfully rooted and regenerated plantlets which exhibited normal growth in the greenhouse. Enhanced plant regeneration, an essential criterion for commercial micropropagation, was achieved.

Aggregation Behavior Modulation of 1-Dodecyl-3-methylimidazolium Bromide by Organic Solvents in Aqueous Solution

Material preparation in ionic liquids and environmental pollution control by ionic liquids are often closely dependent on the aggregation behavior of ionic liquids in solution. In the present work, conductivity, fluorescence probe, and dynamic light scattering techniques have been used to study the effect of organic solvents on the aggregation behavior of 1-dodecyl-3-methylimidazolium bromide in water. It was shown that the critical aggregation concentration (CAC), the ionization degree of the aggregates (α), and the standard Gibbs energy of aggregation (ΔG(m)°) of the ionic liquid increase, while its aggregation number (N(agg)) and aggregates' size decrease with increasing concentration of organic additives in water. These results have been discussed from the favorable interactions of alkyl chain of the ionic liquid with the mixed solvents. It is suggested that the solvophobic parameter, characterized quantitatively by Gibbs energy of transfer of hydrocarbon from gas into a given solvent, can be used to account for the effect of organic additives on the formation and growth of the ionic liquid aggregates in water. Aggregation behavior of ionic liquids in aqueous organic solutions can be modulated simply by the solvophobic parameters of hydrocarbon in the mixed solvents.

Can Nitrilotriacetic Acid (NTA) Act as a Habit Modifier for Rock Salt Crystals? An Answer from Computational and Experimental Studies

It has been reported that nitrilotriacetic acid (NTA) has no effect on the growth habit of sodium chloride. We report here that NTA acts as a habit modifier for rock salt. The concentration of NTA required to influence the habit of salt crystals from cubic to octahedron is much less compared to the concentrations of other organic additives used for this purpose. The influence of NTA under different pH conditions toward the morphology of sodium chloride crystals has been investigated by experimental and computational methods. Prior to any analysis, a conformational search of NTA and its three dissociated forms was performed with molecular mechanics MM2* and DFT (B3LYP/6-31+G*) methods in aqueous phase. The low energy conformers were used to derive quantum chemically molecular electrostatic potential (MESP) to examine the possible sites of interaction for NTA and its dissociated forms with the important planes of NaCl. Three dimensional (3D)-slab model calculations performed to mimic the surfaces of sodium ...

Palladium crystals of various morphologies for SERS enhancement

Palladium (Pd) nanostructures with urchin-like, hemispherical, flower-like, and plate-like morphologies were controllably deposited on silicon substrates in aqueous hydrogen fluoride (HF) solution at room temperature. The morphology of the Pd nanostructures changed from urchin-like to hemispherical and flowerlike in the presence of polyvinyl pyrrolidone (PVP, MW = 55 000) and cetyltrimethylammonium bromide (CTAB), respectively. The Pd nanostructures were characterized by transmission electron microscopy, high-resolution transmission electron microscopy, field emission scanning electron microscopy, energy-dispersive X-ray, and X-ray diffraction. The size and shape of palladium nanostructures were investigated as a function of metal precursor concentration, reaction time and organic additive concentration. The possible formation mechanisms were discussed. In addition, the morphology-dependent surface-enhanced Raman scattering (SERS) of the as-synthesized Pd nanostructures were investigated. The results showed that urchin-like Pd nanostructures had the highest SERS activity than the other Pd nanostructures for Rhodamine 6G (R6G) probe molecules.

Toward the Crystallization of Photosystem II Core Complex from Pisum sativum L.

The crystallization of the higher plant ∼1 gigadalton homodimeric lipid-pigment−protein complex of photosystem II constitutes a challenging undertaking that has not been crowned with success to date. In the continuation of our previous efforts (Kuta-Smatanova et al. Photosyn. Res. 2006, 90, 255−259) that had provided needle and plate crystals of plant photosystem II for the first time, we report on a study to crystallize three-dimensional crystals of the photosystem II from Pisum sativum L. suitable for X-ray analysis. In our screening, we optimized temperature, supersaturation rate, and concentrations of detergents, buffers, salts, and organic additives. We used a sitting and hanging drop vapor-diffusion method, microbatch under oil and counter-diffusion techniques, and direct and cross-influenced procedures. We have identified that the major limiting factors for the growth of crystals are the photosystem II stability and requirement of indispensable divalent cations. The newly proposed physicochemical c...

Two variable semi‐empirical and artificial neural‐network‐based modeling of peptide mobilities in CZE: The effect of temperature and organic modifier concentration

This work was focused on investigating the effects of two separation influencing parameters in CZE, namely temperature and organic additive concentration upon the electrophoretic migration properties of model tripeptides. Two variable semi-empirical (TVSE) models and back-propagation artificial neural networks (ANN) were applied to predict the electrophoretic mobilities of the tripeptides with non-polar, polar, positively charged, negatively charged and aromatic R group characteristics. Previously published work on the subject did not account for the effect of temperature and buffer organic modifier concentration on peptide mobility, in spite of the fact that both were considered to be influential factors in peptide analysis. In this work, a substantial data set was generated consisting of actual electrophoretic mobilities of the model tripeptides in 30 mM phosphate buffer at pH 7.5, at 20, 25, 30, 35 and 40 degrees C and at four different organic additive containing running buffers (0, 5, 10 and 15% MeOH) applying two electric field strengths (12 and 16 kV) to assess our mobility predicting models. Based on the Arrhenius plots of natural logarithm of mobility versus reciprocal absolute temperature of the various experimental setups, the corresponding activation energy values were derived and evaluated. Calculated mobilities by TVSE and back-propagation ANN models were compared with each other and to the experimental data, respectively. Neural network approaches were able to model the complex impact of both temperature and organic additive concentrations and resulted in considerably higher predictive power over the TVSE models, justifying that the effect of these two factors should not be neglected.

Exfoliation of Single-Walled Carbon Nanotubes Induced by the Structural Effect of Perylene Derivatives and Their Optoelectronic Properties

We designed an innovative and effective dispersion system for single-walled carbon nanotubes (SWCNTs) by introducing an exfoliation concept. Perylene derivatives were used as organic additives for dispersion of the SWCNTs. The SWCNT solutions were characterized with UV−vis−NIR absorption spectroscopy and transmission electron microscopy. Our newly designed dispersion system improved the degree of dispersion of the SWCNTs more than 10% and showed much better dispersion stability, compared to a conventional dispersion system. Furthermore, from the optoelectronic properties, we found that our designed dispersion system reduced the sheet resistance by about 50% at similar transmittance. Our analysis demonstrated that our designed dispersion system could provide a well-dispersed SWCNTs solution with long-term dispersion stability even under an extremely low dispersant concentration for dispersion of SWCNTs (weight ratio of CNTs/organic additive = 1, concentration of organic additives = 0.1 g/L, sonic treatment...

Influence of pulse plating conditions on the structure and properties of pure and composite nickel nanocrystalline coatings

An additive-free Watts type bath containing micron- and nano-SiC particles (1 μm and 20 nm respectively), as well as ultrafine-WC particles (200 nm), was used for the production of pure Ni and nickel matrix composite electrocoatings under both direct and pulse current conditions. Moreover, nickel nanocrystalline deposits were obtained from a Watts type bath containing small amounts of 2-butyne-1,4-diol, in order to investigate the combined advantages of additives and pulse technique on the properties of the deposits. The influence of the variable electrolysis parameters, the particle size and the organic additive concentration on the surface morphology, the structure and properties of the deposits were discussed. It has been proved that the application of pulse electrodeposition affects drastically the structural characteristics and properties of the deposits and under well-defined conditions could lead to the preparation of nanostructured materials with improved mechanical properties.

Capillary electrophoresis with capacitively coupled contactless conductivity detection for low molecular weight organic acids in different samples

CE with capacitively coupled contactless conductivity detection (CE-C(4)D) was explored and validated for the identification and quantification of organic acids in various types of samples. The analyses were performed under optimized conditions, using a buffer system composed of 20 mM MES-histidine (His), pH 6.0, 0.1 mM CTAB, 0.025% HP-beta-CD, and 10% methanol. The investigation included a study of the effects of buffer pH, concentration of CTAB, type and concentration of organic additives, on the migration behavior, resolution and selectivity of the organic acids. The intra- and interday RSDs (n = 6) obtained for migration time and peak area were typically in the range of 0.12-2% and 0.5-4%, respectively. Linearity, detection limits, and repeatability were evaluated. In order to evaluate the application potential of the developed method, real samples from different sources were analyzed. The results demonstrate that CE-C(4)D is a versatile tool for analyzing organic acids in beverages, Chinese herbal medicines (CHM) and plants as it allows for their detection, identification, and quantification.

The effect of processing conditions on the photoluminescence properties of Ca(Y 0.94Eu 0.06)BO 4 phosphors synthesized by ultrasonic spray pyrolysis

The effect of processing conditions on the photoluminescence properties of the Ca(Y 0.94Eu 0.06)BO 4 phosphors that were synthesized by ultra-sonic spray pyrolysis was investigated. The morphology and size of the Ca(Y 0.94Eu 0.06)BO 4 phosphors were controlled by changing processing conditions, including precursor concentration, organic additives content, and air flow rate, and substantially affected their luminescent properties. Lower precursor concentration yielded higher emission intensity. High emission intensity was obtained for an air flow rate of 5–20 l/min. The magnitude of the emission intensity on organic additive concentration followed the order of 0.5 M>0.3 M>0.7 M.

Elaboration by Tape Casting and Hot Rolling of Copper/Silicon Carbide Composite Thin Films for Microelectronic Applications

During the last decade, the use of metal matrix composites (MMCs) materials such as Al/SiC or CuW for microelectronic devices have made powder modules more reliable. Today, due to the continuous increasing complexity, miniaturization and high density of components in modern devices, high power microelectronic industries are looking for new adaptive thin films with high thermal conductivity, low coefficient thermal expansion, and good machinability. This paper presents an original and new elaboration method (tape casting and hot rolling) which has been optimized in order to elaborate copper/silicon carbide thin film composite materials. The first part presents the optimization of the tape casting parameters used (powder mixing; optimization of the nature and concentration of organic additives; tape casting, debinding and pre-sintering conditions). In the second part, the main characteristics of thin film obtained are discussed, such as thermomechanical properties of the composite Cu/SiC thin films.

Effect of organic acids on the hydrothermal crystallization of Fe(OH)3

We have studied hydrothermal crystallization of amorphous iron(III) hydroxide in aqueous suspensions containing organic acids. The results indicate that the nature and concentration of organic additives (as well as the pH of the suspension, temperature, Fe(OH)3 concentration, and gaseous atmosphere) have a significant effect on the physicochemical properties of the resulting particles. Organic substances that form stronger complexes with Fe(III) and, accordingly, are more strongly adsorbed on the surface of Fe(OH)3 particles are shown to have a stronger effect on the morphology and phase composition of the forming iron oxide particles. A mechanism underlying the effect of organic acids on Fe(OH)3 crystallization is proposed.

Monitoring of the conversion from triptolide to tripchlorolide in triptergium wilfordii by micellar electrokinetic caillary chromatography

A novel concocting method to convert Triptolide (T) into Tripchlorolide (T 4) in the traditional Chinese herb Tripterygium wilfordii Hook F. and a micellar electrokinetic capillary chromatographic (MEKC) approach by which the conversion of Triptolide (T) and Tripchlorolide (T 4) was identified and determined had been established. Investigations of the influence of different pH values of boric acid and borax buffer and of sodium dodecyl sulfate (SDS) and organic additive concentrations had been carried out, and the optimum separation for T and T 4 was achieved using boric acid and borax of pH 7.0 with 30 mM SDS and 20% (volume ratio) methanol as the running buffer. It was found that MEKC exhibited good accuracy, precision and repeatability and the content of T 4 was greatly increased in the herb that was treated by the new concocting method.

The “recipe” of the stucco sculptures of Giacomo Serpotta

Mineralogical and chemical data (organic) of some representative samples collected from stucco-works by the famous Sicilian sculptor Giacomo Serpotta (Palermo, 1656–1732) have been combined with the aim of ascertaining their manufacture technology in the light of local historical sources. A complete correspondence between samples belonging to the “ Victory” statue (1723) and the S. S. Rosario oratory (1685–1689) as regards stratigraphy, mineralogy of sand aggregate, composition of binder matrix, and nature and concentrations of organic additives is pointed out. Considering that the studied works of art cover more than 35 years of the artist’s activity, it is consequential to think of a well-established “recipe”. A significant spin-off should be derived in the comprehension of deterioration processes and correct design of restoration works.

Micellar association in simultaneous presence of organic salts/additives

AbstractViscosity measurements under Newtonian flow conditions had been performed on cetyltrimethylammonium bromide (CTAB) aqueous solutions in the combined presence of sodium salts of aromatic acids (sodium salicylate, NaSal; sodium benzoate, NaBen; sodium anthranilate, NaAn) and organic additives (1‐hexanol, C6OH; n‐hexylamine, C6NH2) at 30°C. On addition of C6OH or C6NH2, the viscosity of 25 mM CTAB solution remained nearly constant without salt as well as with a lower salt concentration. This is due to low CTAB concentration which is not sufficient to produce structural changes in this concentration range of salts. However, as the salt concentration was increased further, the effect of C6OH/C6NH2 addition was different with different salts: The viscosity first increased; then a decrease was observed with the former while with C6NH2 a decrease followed by constancy appeared in plots of relative viscosities (ηr) vs. organic additive concentrations. At further higher salt concentration, the magnitude of ηr was much higher. The viscosity increase is explained in terms of micellar growth and the decrease in terms of swollen micelle formation (due to interior solubilization of organic additive) or micellar disintegration (due to formation of water + additive pseudophase).