Influence Of Different Concentration Research Articles

In vitro сlonal propagation of repairing hybrids of wild strawberry Fragaria ananassa Duch.

The features of the clonal propagation technology of repairing hybrids of wild strawberry (Fragaria ananassa Duch.) have been studied. Traditionally, the strawberry is vegetative propagated by grafting, but for the repairing varieties of strawberry, this method is less effective because plants form only 1–2 rosettes per plant during the growing season. The clonal micropropagation in vitro is the alternative method of reproduction to vegetative propagation. For the introduction of strawberry in vitro culture apical stolons and non-rooting rosettes collected from April to June have been taken. To obtain polyploid plants formed during callusogenesis process, stem and leaf explants were used. The main medium was Murashige-Skug agar medium (MS) supplemented with plant growth regulators (PGRs) and ascorbic acid (1.5 mg/l), the control medium was MS medium without PGRs. The influence of different concentration of cytokinin (0,3-1 mg/l 6-BAP) on the multiplication and auxin (0,5-1 mg/l IAA) on rooting of repairing hybrids of strawberry in vitro culture have been studied. The optimal concentrations of 6-benzylaminopurine (0.3 mg/l) were determined at the propagation stage and the same for α-indoleacetic acid (0,5 mg/l) on the rooting stage have been determined. Microrosettes with a well-developed root system obtained during in vitro cultivation were acclimatized and grown on hydroponics. Adapted to growth in the open ground plants were used as a planting material, which was propagated in a greenhouse.

FORMULATION OF CONTROLLED RELEASE MATRIX TABLET OF DICLOFENAC SODIUM USING CROSS LINKED STARCH UREA

The present works aims to develop controlled release matrix tablet of diclofenac sodium with modified starch cross linked starch urea as an sustained release polymer and to evaluate the prepared dosage form for physical parameters like weight variation, hardness, fria bility and drug content. Cross linked starch urea is modified starch introducing desirable alterations in the starch structure so that its behavior is predi ctable and controllable. In the current study, the influence of different concentration of polymer o n erosion of matrix system was studied with a view to develop controlled release formulation of diclofenac sodium. The Diclofenac sodium tablet was prepared by wet granulation method. The result from in vitro drug release study indicated that formulation F 1 to F6 were with different polymer concentration and F5 found to release the drug at a steady state over an extended period of time up to 24 h.

Synthesis of Cu2ZnSnS4 nanoparticles and controlling the morphology with polyethylene glycol

Cu2ZnSnS4 nanoparticles were synthesized by wet chemical technique using metal thiourea precursor at 250°C. The structural and morphological properties of as grown nanoparticles have been characterized by X-ray diffraction, Raman spectroscopy, scanning electron microscopy and transmission electron microscopy. The influence of different concentration of polyethylene glycol as structure directing agent on the morphologies of Cu2ZnSnS4 nanoparticles are investigated on thin films deposited by spin coating technique. The mean crystallite size of the Cu2ZnSnS4 nanoparticles was found to improve with polyethylene glycol concentration. Scanning electron microscopy images of Cu2ZnSnS4 revealed aggregated spherical shaped nanoparticles whereas the polyethylene glycol assisted Cu2ZnSnS4 nanoparticle films show nanoflakes and nanorods structures with increasing concentration of polyethylene glycol. Transmission electron microscopy analysis has also been performed to determine the size and structure of nanorods. UV–vis absorption spectroscopy shows the broad band absorption with optical bandgap of 1.50eV for polyethylene glycol assisted Cu2ZnSnS4 films.

Effect of cobalt doping on structural, optical and redox properties cerium oxide nanoparticles

Cobalt-doped ceria nanoparticles were synthesized using the polyol method under co-precipitation hydrolysis. The structural, morphological, optical and redox properties were observed to investigate the influence of different concentration of cobalt ion doping on the prepared CeO2 nanomaterials in terms of X-ray diffraction, field-emission transmission electron microscopy, thermogravimetric analysis, Fourier-transform infrared spectroscopy, UV/vis absorption spectroscopy and temperature program reduction techniques. The optical band gap energy was calculated from the optical absorption spectra for doped ceria nanoparticles, which have been found to be 2.68, 2.77, and 2.82 eV for the 2, 4, and 7 mol% Co ion-doped CeO2 nanoparticles, respectively. As observed, the band gap energies increases as the doping Co ion concentrations increased, which could be due to significant increased oxygen vacancies with Co doping. The synergistic interaction between Co and CeO2 was the main factor responsible for high catalytic activity of cobalt-doped CeO2 model catalysts.

Controlled deposition and enhanced visible light photocatalytic performance of Pt-modified TiO2 nanotube arrays

Highly ordered TiO2 nanotube arrays (TiO2 NTAs) have been fabricated by the potentiostatic anodization method with Ti foils. Pt nanoparticles have been successfully deposited onto TiO2 NTAs by UV light photoreduction method. In this work, X-ray diffraction, field emission scanning electron microscope, high resolution transmission electron microscopy, X-ray photoelectron spectroscopy, ultraviolet-visible spectroscopy and energy dispersive X-ray spectrometer methods were adopted to characterize the samples. The influence of different concentration of H2PtCl6 precursor solution on the morphology and photocatalytic performances of samples was discussed. The SEM observations showed that Pt nanoparticles distributed on the wall of TiO2 nanotubes uniformly. UV–vis spectra analysis showed that the light absorption of Pt/TiO2 NTAs has been extended to the visible light range. When the concentration of H2PtCl6 was 3mM, the prepared sample showed the highest photodegradation rate. After irradiated under visible light for 2h, the degradation rate of methyl orange solution reached 84.27%. Under the same condition, no obvious photodegradation of methyl orange was found for TiO2 NTAs. Kinetic research showed that photodegradation process followed the first-order reaction, the apparent reaction rate constant of 3 Pt/TiO2 NTAs was 1.493×10−2min−1.

Synthesis and Characterizations of Silver Colloid Nanoparticles Stabilized by Dextran

This study aims to investigate the influence of different concentration of silver nanoparticles in Dextran (Dx) suspension. The silver nanoparticles (AgNPs) were prepared by chemical reduction method using reduction agents, Dextran (Dx) under moderate temperature at different concentration. Three different sample solutions were prepared viz., 0.4, g0.8 and 1.2% (w/v) Dx at a constant temperature (80C). Silver nitrate (AgNO3) was taken as the metal precursor while Dx was used as the solid support and polymeric stabilizer. The formation of nano silver was identified by the color change from white precipitate to yellowish-brown color. Formation of Ag-NPs was determined by UV–Vis spectroscopy where surface plasmon absorption maxima can be observed at 412-437 nm from the UV-Vis spectrum. The synthesized nanoparticles were also characterized by X-ray diffraction (XRD). The peaks in the XRD pattern confirmed that the AgNPs possessed a face-centered cubic and peaks of contaminated crystalline phases were unable to be located. The Fourier transform infrared (FT-IR) spectrum suggested the complexation present between Dx and AgNPs. Scanning Electron Microscopy (SEM) with EDX and Atomic Force Microscopy (AFM) was applied to characterize the morphology, particle size distribution of the AgNPs. The average particle size of the stabilized samples ranged from 10-40 nm. It was demonstrated that this convenient method is versatile to produce silver nanoparticles with controlled size and shape.

The thermoluminescence and optically stimulated luminescence properties of Cr-doped alpha alumina transparent ceramics

Abstract Polycrystalline Cr:α-Al 2 O 3 transparent ceramics were fabricated by conventional solid-state processing under vacuum condition. The SEM microstructure photographs of Cr:α-Al 2 O 3 transparent ceramics doped with different content of Cr 2 O 3 were investigated. The absorption, emission spectra, thermoluminescence and optical stimulated luminescence of Cr:α-Al 2 O 3 transparent ceramics were comparable to those of Cr:α-Al 2 O 3 crystals. The influence of different concentration of Cr 2 O 3 on the thermoluminescence and optical stimulated luminescence properties of Cr:α-Al 2 O 3 transparent ceramics was discussed. It showed so interesting results with high TL sensitivity and high stability of OSL signal that Cr:α-Al 2 O 3 transparent ceramics might be a promising material in TL dosimetry and replace Cr:α-Al 2 O 3 crystals.

Investigation into the Electromagnetic Interference Shielding Effectiveness of Silicon Rubber Filled with Carbon Fiber

In this paper, the silicone rubber composed of carbon fibers was prepared. The influence of different concentration of carbon fibers on the conductivity, electromagnetic shielding interference effectiveness property of the silicone rubber was discussed from the point of view of condition of carbon fiber and silicone rubber. The results showed that there existed the extreme conductivity and shielding effectiveness (SE) across the tested frequency range from 2.6 GHz to 3.95 GHz of silicone rubber composites filled with carbon fibers. When the content of the carbon fibbers was 50 parts per hundred of rubber (phr), the SE values of composites were typically above 63 dB and close to the extremum. The compact packing structure of carbon fibers does not play an important role in improved the conductivity of composite. The SE of the composite depends on the conductivity of composite.

Influence of different concentration of heavy metals on the seed germination and growth of tomato

Some heavy metals in higher doses may cause metabolic disorders and growth inhibition for most of the plant species. This study was performed in order to evaluate two tomato varieties (Barakat and Local tomato) response to ordinary Heavy Metals (Fe, Pb and Cu) in northern of Iran. Five doses (0, 0.001, 0.01, 0.1 and 1%) of lead acetate, cupric carbonate and ferric chloride were investigated. The experiment was conducted under 12±2h photoperiodic laboratory condition in a laboratory germinator. Results showed that the reaction of varieties to different heavy metal compounds and those doses is varied and Barakat variety has greater resistance in more indices. Also, heavy metals kind and different doses of these compounds affected the germination and some growth indices. In this experiment the highest inhibition on shoot length 2.66 cm, root/ shoot ratio 0.87, moisture content 0.31 g, fresh weight 0.32 g and dry weight 0.059 g were obtained from Fe compound, however; had not significance different with other heavy metal compounds in case of root length 3.39 cm and coefficient of germination velocity 0.27% (P≤0.05). Also, dose of 1% appeared highest undesirable effect on all evaluated indexes.

The Influence of Electroless-Silver Coated Cenosphere Powders on the Electromagnetic Shielding Interference Effectiveness and Mechanical Properties of the Silicone Rubber

Silver plating cenosphere powders were developed by electroless plating method. After being mixed with silver plating cenosphere powders and curing agent, silicone rubber composites was obtained. The surface morphology, microstructure and cross-section of Ag-coated cenosphere powders and composites were analyzed using scanning electron microscopy (SEM) and X-ray diffraction (XRD). The influence of different concentration of Ag-coated cenosphere powders on the conductivity, electromagnetic shielding interference effectiveness and mechanical properties of the silicone rubber was discussed from the point of view of condition of Ag-coated cenosphere powders and silicone rubber. The results showed that the smooth and compact silver coating was deposited on the surface of cenosphere powders. The Ag-coated cenosphere powders possessed good oxidation resistance and enough strength to resist being crushed during the preparation of composites. The adhension between the silver film and cenosphere powders was good. There existed the extreme shielding effectiveness (SE) of silicone rubber composites filled with Ag-coated cenosphere powders. The electrical conductivity no longer plays an important role in enhancing the SE of composites when the SE of composites reaches the extremum. When the content of the Ag-coated cenosphere powders was 180 parts per hundred of rubber (phr), the SE values of composites were typically above 80 dB and close to the extremum across the tested frequency range from 2.6 GHz to 3.95 GHz. And the mechanical properties of composites with 180 phr were not degraded obviously.

Sucrose/bovine serum albumin mediated biomimetic crystallization of calcium carbonate

To understand the role of the sucrose/bovine serum albumin system in the biomineralization process, we have tested the influence of different concentration of the sucrose/bovine serum albumin (BSA) on calcium carbonate (CaCO3) precipitation. The CaCO3 crystals were characterized by scanning electron microscope (SEM), Fourier transform infrared spectrograph (FT-IR) and powder X-ray diffractometry (XRD). The possible formation mechanism of CaCO3 in the sucrose/bovine serum albumin system was discussed.

Inter- and Intraconfigurational Transitions of Nd3+ in Hexafluorocryolite-type K3YF6 Lattice

Vacuum ultraviolet, visible, and infrared luminescence of Nd3+ incorporated into hexafluorocryolite-type K3YF6 lattice were investigated. Emission from the 4f25d1 at 8 K is observed after the excitation of 4f25d1 by synchrotron radiation. At higher temperatures only the transitions within the 4f shell are observed with the significant participation of 2G(2)9/2 emission to the lower 4f levels. The difference between near-infrared emission spectra excited at 800 and 186 nm implies that emission band excited at 186 nm consists of overlapping transitions originating from the 4F3/2 and higher energy levels. The room temperature 4F3/2 emission lifetime and the influence of different concentration of Nd3+ ions on rate of the self-quenching luminescence lifetime have been studied in details. The 4F3/2 emission lifetime measured at 2.6 × 1019/cm3 Nd3+ concentration in K3YF6 equals 5.3 ms and is the highest value ever reported for Nd3+-doped crystals.

Influence of ammonium, nitrate and nitrite on the performance of the pure culture of Acinetobacter junii

The influence of different concentration ranges (0-500 mg/L) of ammonium, nitrate and nitrite presence in the wastewater, on the performance of the pure culture of phosphate-accumulating bacterium Acinetobacter junii in the anaerobic and aerobic conditions, was investigated. A. junii was able to use ammonium and nitrate salts as the source of nitrogen, unlike in the case of nitrite salt. Comparing to the control reactors with the peptone and yeast extract as the sources of nitrogen, at the lowest tested concentration of ammonium and nitrate the performance of the system was inhibited due to the nitrogen deficit in the wastewater, while at the highest concentration it was positively influenced. Nitrite in all concentrations detrimentally affected the phosphate release and uptake rates, chemical oxygen demand uptake rates, nitrogen uptake rates, as well as multiplication of A. junii. The higher the nitrite concentration, the more pronounced was the effect. At the highest nitrite concentration tested a complete failure of the system was observed.

Effect of Ethanol on the Oxidation of Atrazine in the Remediation of Contaminated Soil

The oxidation of an atrazine solution obtained from a flushing treatment of a contaminated soil was investigated. Experimental tests were performed on an artificially contaminated standard soil. Atrazine was removed from the soil by flushing with an aqueous solution at 5% volume of ethanol. Oxidative Fenton-type treatment on the extracted solution was then performed in order to transform atrazine into its by-products. The influence of different concentration of ethanol on atrazine oxidation was studied. Results show that the oxidative treatment is strongly affected by the ethanol residual amount. The degradation mechanism of atrazine during oxidation with Fenton's reagent in the presence of ethanol was also investigated.

The aqueous photochemical transformation of acrylic acid

Acrylic acid in sea water is thought to occur mostly as the product of microbial cleavage of dimethylsulphoniopropionate (DMSP), but could also be a pollutant introduced by waste waters of the organic chemical industry. Solutions of acrylic acid in natural and artificial sea water, and distilled and riverine water were photolyzed using a photochemical reactor and exposure to sunlight. The transformation of acrylic acid comprises the decarboxylation of the carboxylic group and subsequent polymerization to a polyethylene type molecule. Kinetic studies showed the lowest reaction rate in distilled water and somewhat higher and very similar rates in other aqueous media. The approximately similar reaction rates in all natural waters studied suggest that inorganic ions, especially Na+, Mg2+ and halides, and dissolved organic matter (probably humics) enhance the reaction rates. On studying the influence of different concentration ranges on the reaction kinetics, an exponential increase of rates with decreasing concentration was found. The reaction rate in the sea water solution in field conditions is rather slow. In thirty days exposure about 15% of the reactant was transformed. This reaction seems to be important in the marine environment in specific conditions, especially in phycospheres and macroaggregates where higher concentrations of acrylic acid inhibit the bacterial metabolism.

Gamma‐radiation induced grafting of acrylonitrile onto guar gum: Influence of reaction conditions on the properties of the grafted and saponified products

AbstractIn the gamma‐radiation induced grafting of acrylonitrile onto guar gum, the influence of different concentration of the monomer acrylonitrile on the PAN add‐on, the number average molecular weight of the PAN side chains, and the grafting frequency of the PAN side chains are reported. At 0.3 Mard dosage, the PAN add‐on were 32.4, 48.5, and 66.2% and the number average molecular weight of the PAN side chains were 59,700, 132,200, and 238,900, respectively, at three different reaction conditions. The frequency of grafting also showed considerable variation at 0.2 Mrad dosage, for all three sets of samples. The viscosity of the aqueous dispersions of the saponified samples at different concentrations are also reported. The water absorbency of the saponified samples were evaluated and the values were around 250 g/g. The fall in viscosity of the aqueous dispersions on storage were also evaluated. The observed fall in viscosity was lower in the case of the product with higher PAN content. © 1993 John Wiley & Sons, Inc.