scholarly journals Studies on the effect of Dielectric constants of Aquo-DMF Solvent- System of the Solvolysis Products of Nicotinates

2020 ◽  
Vol 16 (5) ◽  
pp. 72-77
Author(s):  
RENU KUMARI ◽  
◽  
R.T. SINGH ◽  
Keyword(s):  
Solvent System ◽  
Dielectric Constants ◽  
Dimethyl Formamide ◽  
Kinetic Temperature ◽  
Methyl Nicotinate ◽  
Increase With Increase ◽  
Solute Interaction ◽  
Simultaneous Decrease ◽  
Reaction Media ◽  
Activated Complex

From the eenhancement observed in G* values with simultaneous decrease in the values of H and S* of the reaction, it is concluded that the organic co-solvent dimethyl formamide (DMF) acts as entropy controller and enthalpy stimulator solvent for alkali catalysed solvolysis of Methyl nicotinate. Form the evaluated values of water molecules associated with the activated complex of the reaction which are found to increase with increase in the temperature of the reaction, it is inferred that the bimolecular mechanistic path is changed to unimolecular in presence of the organic component (DMF) of the reaction media. The numerical value of Iso-Kinetic temperature of the reaction which comes to be nearly 287.5 (below 300) indicates that there is weak but considerable solvent-solute interaction in the aquo-DMF solvent system.

Solvent effect and Activation Parameters: A Kinetic Reaction of Ethyl Caprylate in Water-Acetone Media

2021 ◽  
pp. 441-444
Author(s):  
A.K. Singh
Keyword(s):  
Organic Solvent ◽  
Water Concentration ◽  
Activation Parameters ◽  
Kinetic Temperature ◽  
Kinetic Reaction ◽  
Kinetic Result ◽  
Solute Interaction ◽  
Eyring Equation ◽  
Reaction Media ◽  
Hydrolysis Of

The kinetic result of hydrolysis of Ethyl Caprlyate has been investigated at different composition of aqueous-organic solvent with Acetone (30-70% v/v) over the temperature range of 20 to 400c. The calculated result follows second order kinetics and is observed that the rate decreases with increasing proportion of Acetone. This behavior is attributed electrostatic nature that various solvent-solute interaction in reaction media. Linear plots of Logk against water concentration shows that equilibrium shifted from dense form to bulky form. Iso-kinetic temperature has been determined with the help of slopes of (ΔH*) versus (ΔS*). Thermodynamic parameter has been calculated with the help of Wynne-Jones and Eyring equation.

scholarly journals Studies on the effect of Aquo-Dioxan Solvent System on the biochemical behaviour of the Substituted Valerates

2020 ◽  
Vol 16 (5) ◽  
pp. 63-71
Author(s):  
SUSHMA KUMARI ◽  
Keyword(s):  
Free Energy ◽  
Solvent Effect ◽  
Hydrolysis Product ◽  
Solvent System ◽  
Simultaneous Increase ◽  
Solute Interaction ◽  
Reaction Media ◽  
Energy Activation

Valerates and Substituted Valerates have been found to be useful for humanbeings as its hydrolysis product i.e. valence acid is used in the society in the form of perfumes flavours platister, vinyl stabilizer and pharmaceuyicals. With a views to study the solvent effect of 1:4 dioxan on the biochemical behivour of the hydrolysis product of a substituted valerate, the kinetic of Alkali catalysed of mothyl iso-valerate was studies in aquodioxan media. Increase observed in free energy activation with simultaneous increase in the value of both the activation H* and S*, it is concluded that in the presence of dioxan with reaction media, the reaction becomes enthaipy dominating and entropy controlled. From the evaluated values of the reaction which comes to be 329.0, it is inferred that Barclay-Butler rule is obeyed by the reaction and there is strong solvent- solute interaction in presence of dioxan the reaction media.

Static dielectric constants of the N,N-dimethylformamide/2-methoxyethanol solvent system at various temperatures

1992 ◽  
Vol 70 (12) ◽  
pp. 2895-2899 ◽  
Author(s):  
Fulvio Corradini ◽  
Luigi Marcheselli ◽  
Lorenzo Tassi ◽  
Giuseppe Tosi
Keyword(s):  
Liquid State ◽  
Specific Interaction ◽  
Solvent System ◽  
Liquid Mixtures ◽  
Dielectric Constants ◽  
Empirical Equations ◽  
Binary Liquid ◽  
Fraction Mixture ◽  
Static Dielectric Constants ◽  
Formation Of Complexes

Measurements of static dielectric constants (ε) have been made for binary liquid mixtures of N,N-dimethylformamide (DMF)/2-methoxyethanol (ME) at 19 temperatures ranging from −10 to +80 °C. Some empirical equations of the type ε = ε(T), ε = ε(X1), and ε = ε(T,X1) have been applied to check their validity. The εE values, which refer to the deviation of the dielectric constants of the binaries from the values arising from mole fraction mixture law, have been calculated. Deviations from ideal behaviour have been found to be positive at all temperatures. The positive εE values are attributed to a specific interaction between unlike molecules, which leads to the formation of complexes between DMF and ME in the liquid state. These nDMF•mME complex moieties were found to have the stoichiometric ratios 2:1, 1:1, and 1:2 in the temperature range of −10 to +80 °C.

Microwave Dielectric Properties of A-Site Modified Pb(Mg1/2W1/2)O3

2007 ◽  
Vol 280-283 ◽  
pp. 1-4
Author(s):  
Jian Jiang Bian ◽  
Hong Bo Gao ◽  
Xiao Wu Wang
Keyword(s):  
Dielectric Properties ◽  
Structural Difference ◽  
Microwave Dielectric Properties ◽  
Dielectric Constants ◽  
Sintering Behavior ◽  
Microwave Dielectric ◽  
Increase With Increase ◽  
A Site ◽  
Perovskite Type ◽  
Perovskite Type Structure

The sintering behavior, microstructure and microwave dielectric properties of A-site modified Pb(Mg1/2W1/2)O3 with Ca2+, Ba2+and La3+ were investigated in this paper. It is discovered that a series of single-phase perovskite type solid solutions with A-site vacancies were formed for Pb1-3/2xLax(Mg1/2W1/2)O3 (0 £ x £ 2/3)). The solid solution took cubic perovskite type structure (Fm3m)with random distribution of A-site vacancies when 0 < x < 0.5, and tetragonal or orthorhombic structure with the ordering of A-site vacancies when 0.5 £ x £ 2/3. However, the solid solubility of Ba(Mg1/2W1/2)O3 and Ca(Mg1/2W1/2)O3 in Pb(Mg1/2W1/2)O3 is limited to 15 and 5 mol%, respectively, in spite of no structural difference between the end member. It was also found that the A-site substitution with Ca2+, Ba2+and La3+ for Pb2+ has no influences on the degree of B-site ordering between Mg2+ and W6+. However, the antiferroelectric Tc decreases with increase in the content of A-site substitution. The dielectric constants and temperature coefficient of resonant frequency of La3+ modified Pb(Mg1/2W1/2)O3 are much lower than that of. Ca2+and Ba2+ modified Pb(Mg1/2W1/2)O3, and decrease with increasing La content. However, its Q×f values is much higher than that of Ca2+and Ba2+ modified Pb(Mg1/2W1/2)O3, and increase with increase in La content. Relatively good combination microwave dielectric properties were obtained for Pb1-3/2xLax(Mg1/2W1/2)O3 with x=0.56: er=28.7, Q×f=18098, and tf=-5.8ppm/oC.

scholarly journals ANTI-TUMOR ACTIVITY OF BACTERIAL LECTIN AND 5-METHYLURACIL ADDUCT

2014 ◽  
Vol 2 ◽  
pp. 307-312
Author(s):  
Elena Welchinska
Keyword(s):  
Molecular Complex ◽  
Phase Transfer ◽  
Solvent System ◽  
Biological Properties ◽  
Dimethyl Formamide ◽  
Gas Liquid Chromatography ◽  
Substitution Reactions ◽  
Methods Of Synthesis ◽  
Inhaled Anesthetic ◽  
Anti Tumor Activity

The synthesis was performed using 5-methyluracil mono-and bis-derivatives with the halogen-containing pharmacophore groups in the composition of molecules; their physiochemical and biological properties were studied. These reactions are a typical example of substitution reactions on heteroatom N(1) of uracil molecule using as the second component the reaction of halothane—the known inhaled anesthetic.  The reactions were carried out in a solvent system: benzene-dimethyl formamide and diethyl ether, under conditions of phase transfer catalysis DB-18-crown-6-complex (alkaline medium), by heating from 2 to 11 hours, followed by purification, and drying of the resulting products.  The structure of the synthesized compounds was confirmed by elemental analysis, IR and 1HNMR spectra.  The purity was controlled by the methods of thin-layer and gas-liquid chromatography. Chromatography, IR and 1HNMR spectra of the final products were identified in comparison with the chromatograms, IR and 1HNMR spectra of the initial compounds. Variation of the reaction conditions and changes in methods of synthesis enabled to receive the synthesized compounds of high purity and to increase their practical output up to 43-80%.  Molecular complex of Bacterial lectin and 5-methyluracil bis-derivative was obtained.  The toxicity and anti-tumor activity of some of the synthesized compounds were investigated. We have found that the new molecular complex of Bacterial lectin and 5-methyluracil bis-derivative has high anti-tumor activity in Limphosarcoma Plissa—62.8% (activity criterion >50%), which allows us to consider the synthesized compound as a physiologically active compound with the prospect for further study as a potential vehicle for anti-tumoral treatment in patients. 

DEFORMATION BEHAVIORS OF THERMO-MECHANICALLY PROCESSED Zr-Nb-P ALLOYS

2009 ◽  
Vol 23 (06n07) ◽  
pp. 1816-1821
Author(s):  
SAN KO ◽  
SUN IG HONG
Keyword(s):  
Dislocation Density ◽  
Room Temperature ◽  
Activation Volume ◽  
Phosphorus Addition ◽  
Increase With Increase ◽  
Controlling Mechanism ◽  
Solute Interaction ◽  
Segregation Of Alloying Elements ◽  
Deformation Behaviors ◽  
Phosphorous Content

Deformation behaviors of Zr -1.5 wt. % Nb alloys with no phosphorus addition and with various phosphorous contents (20 ppm, 160 ppm) were investigated in this study. The flow stress of Zr -1.5 Nb increased with the addition of 20~160 ppm phosphorous over a temperature range from room temperature to 450C. The dislocation density appeared to increase with increase of phosphorous content. The increase of strength with phosphorous addition may be linked to the increase of dislocation density. The increase of dislocation density with a higher phosphorous content can be associated with the increase of statistically stored dislocation due to a lower recovery rate. The activation volume decreased from 650~750 b 3 to 450`550 b3 with the addition of 160 ppm phosphorous at room temperature. The rate-controlling mechanism of the deformation of Zr - Nb - P alloy is thought to be the dislocation-solute interaction in which the segregation of alloying elements such as oxygen and phosphorous atoms affects the activation length of dislocations.

Co-solvent system of [EMIM]Ac and DMF to improve the enzymatic saccharification of pussy willow (Salix gracilistyla Miq.)

Holzforschung ◽  
2017 ◽  
Vol 71 (1) ◽  
pp. 43-50 ◽  
Author(s):  
Song Yi Han ◽  
Chan-Woo Park ◽  
Nam-Hun Kim ◽  
Seung-Hwan Lee
Keyword(s):  
Soluble Fraction ◽  
Enzymatic Saccharification ◽  
Solvent System ◽  
Water Soluble ◽  
Dimethyl Formamide ◽  
Glucose Yield ◽  
Water Soluble Fraction ◽  
Salix Gracilistyla ◽  
Mass Ratios

Abstract A co-solvent system consisting of 1-ethyl-3-methylimidazolium acetate ([EMIM]Ac)/N,N-dimethyl formamide (DMF) with different mass ratios was tested to improve the enzymatic saccharification of pussy willow (Salix gracilistyla Miq.). This system effectively lowered the viscosity and increased the biomass loading in the system. The water-soluble fraction obtained from the pure [EMIM]Ac remained constant or increased slightly as the amount of DMF was increased to 70%. At [EMIM]Ac/DMF ratios of 5/5 and 3/7, longer pretreatment times and higher temperatures increased the water-soluble fraction. The crystallinity of the pretreated product was increased by increasing amounts of DMF. The yield of enzymatic saccharification by means of this co-solvent system was comparable to that based on a pure [EMIM]Ac pretreatment, even though the glucose yield was slightly lower in case of DMF amount >70%. Expectedly, longer pretreatment times and higher temperatures improved the yield of enzymatic saccharification.

scholarly journals A DFT Investigation on the Origins of Solvent-Dependent Polysulfide Reduction Mechanism in Rechargeable Li-S Batteries

Catalysts ◽  
2020 ◽  
Vol 10 (8) ◽  
pp. 911
Author(s):  
Guan-Ying Du ◽  
Chi-You Liu ◽  
Elise Y. Li
Keyword(s):  
Density Functional ◽  
Bond Cleavage ◽  
Solvent System ◽  
Dielectric Constants ◽  
Reduction Mechanism ◽  
Dft Methods ◽  
The Density Functional Theory ◽  
High Theoretical Capacity ◽  
Donor Numbers ◽  
The Stability

The lithium-sulfur (Li-S) battery is one of the promising energy storage alternatives because of its high theoretical capacity and energy density. Factors governing the stability of polysulfide intermediates in Li-S batteries are complex and are strongly affected by the solvent used. Herein, the polysulfide reduction and the bond cleavage reactions are calculated in different solvent environments by the density functional theory (DFT) methods. We investigate the relationship between the donor numbers (DN) as well as the dielectric constants (ε) of the solvent system and the relative stability of different polysulfide intermediates. Our results show that the polysulfide reduction mechanism is dominated by its tendency to form the ion-pair with Li+ in different organic solvents.

En face dual fluorescence staining of fatty streaks allows observation of initiation and progression of atherosclerotic lesions

1995 ◽  
Vol 53 ◽  
pp. 864-865
Author(s):  
Anne M. Klinkner ◽  
Crystal R. Waites ◽  
Peter J. Bugelski ◽  
William D. Kerns
Keyword(s):  
Fluorescent Dyes ◽  
Nile Red ◽  
Dimethyl Formamide ◽  
High Cholesterol Diet ◽  
Methods Development ◽  
Atherosclerotic Lesions ◽  
En Face ◽  
Biochemical Evaluation ◽  
Stock Solutions ◽  
Dual Staining

A primary effort in the understanding of the progression of atherosclerotic disease has been methods development for visualization of the atherosclerotic plaque. We introduce a new method for the qualitative analysis of lipids in atherosclerotic fatty streaks which also retains those lipids for biochemical evaluation. An original aspect of the process is the ability to view an entire fatty streak en face, selectively stained for specific lipid classes within the lesion.New Zealand white rabbits were fed a high cholesterol diet(0.15%-0.3% for 14 wks). The aorta was removed and fixed in Carson's phosphate buffered formaldehyde followed by dual staining in the fluorescent dyes Nile red and filipin. Stock solutions of nile red(0.5mg/ml acetone) and filipin(2.5mg/ml dimethyl formamide) were prepared and kept at -20°C; all subsequent steps were at RT. 0.5cm × 1.0cm pieces of aorta were trimmed and adventitia removed. The pieces were then washed 3×15 min in PBS w/o CaMg, soaked in Nile red(NR)/filipin(Fl) stain(100(il NR stock + 200μl Fl stock in 10 ml PBS for 30 min, washed in PBS 3×30 min, rinsed with distilled water, mounted(Crystal Mount, Biomedia) and coverslipped and viewed by fluorescence microscopy.

Electron microscopy studies of PZT ferroelectric film capacitor structures

1992 ◽  
Vol 50 (2) ◽  
pp. 1364-1365
Author(s):  
V. Kaushik ◽  
P. Maniar ◽  
J. Olowolafe ◽  
R. Jones ◽  
A. Campbell ◽  
...  
Keyword(s):  
Electric Fields ◽  
Sol Gel ◽  
Ferroelectric Material ◽  
Dielectric Constants ◽  
Dielectric Films ◽  
Lead Zirconium Titanate ◽  
Si Substrate ◽  
Film Capacitor ◽  
Pzt Films ◽  
High Dielectric

Lead zirconium titanate films (Pb (Zr,Ti) O3 or PZT) are being considered for potential application as dielectric films in memory technology due to their high dielectric constants. PZT is a ferroelectric material which shows spontaneous polarizability, reversible under applied electric fields. We report herein some results of TEM studies on thin film capacitor structures containing PZT films with platinum-titanium electrodes.The wafers had a stacked structure consisting of PZT/Pt/Ti/SiO2/Si substrate as shown in Figure 1. Platinum acts as electrode material and titanium is used to overcome the problem of platinum adhesion to the oxide layer. The PZT (0/20/80) films were deposited using a sol-gel method and the structure was annealed at 650°C and 800°C for 30 min in an oxygen ambient. XTEM imaging was done at 200KV with the electron beam parallel to <110> zone axis of silicon.Figure 2 shows the PZT and Pt layers only, since the structure had a tendency to peel off at the Ti-Pt interface during TEM sample preparation.

Sign in / Sign up

Export Citation Format

Share Document