Determination of Hydrogen Solubility in Heavy Fractions of Crude Oils by a Modified Direct Method

2013 ◽  
Vol 58 (12) ◽  
pp. 3453-3457 ◽  
Author(s):  
Shunfeng Ji ◽  
Zongxian Wang ◽  
Aijun Guo ◽  
Ying Zhou ◽  
Kun Chen
Keyword(s):  
Direct Method ◽  
Hydrogen Solubility ◽  
Crude Oils ◽  
Heavy Fractions

Ab initio structure determination of cytochrome c6 by combined reciprocal space-real space approach

2003 ◽  
Vol 218 (1) ◽  
Author(s):  
K. Chowdhury ◽  
S. Ghosh ◽  
M. Mukherjee
Keyword(s):  
Cytochrome C ◽  
Ab Initio ◽  
Structure Determination ◽  
Direct Method ◽  
Real Space ◽  
Reciprocal Space ◽  
Cytochrome C6 ◽  
Ab Initio Structure ◽  
Space Approach

AbstractThe direct method program SAYTAN has been applied successfully to redetermine the structure of cytochrome c

scholarly journals Determination of the vaporization order of crude oils through the chemical analysis of crude oil residues burned on water

Chemosphere ◽  
2021 ◽  
pp. 131563
Author(s):  
Laurens van Gelderen ◽  
Kristoffer Gulmark Poulsen ◽  
Jan H. Christensen ◽  
Grunde Jomaas
Keyword(s):  
Chemical Analysis ◽  
Crude Oil ◽  
Crude Oils

scholarly journals The determination of the heat of dissociation of fluorine and of the latent heat of vaporisation of lithium

1932 ◽  
Vol 136 (829) ◽  
pp. 76-82 ◽  
Keyword(s):  
High Temperature ◽  
Absorption Spectra ◽  
Latent Heat ◽  
Chemical Reactivity ◽  
Direct Method ◽  
Thermal Methods ◽  
Heat Of Dissociation

The heats of dissociation of chlorine, bromine, and iodine have been determined by thermal methods and estimated to be 58·9, 45·2 and 35·2 kilo-cals. respectively. But no data are yet known concerning the heat of dissociation of fluorine. It is very difficult to subject fluorine to the same treatment as Cl 2 , Br 2 and I 2 ( i. e ., heating to a high temperature in a sealed quartz bulb) owing to its extreme chemical reactivity, and hence no direct method of determining the heat of dissociation of fluorine has yet been devised. In the present paper I have determined it indirectly by interpretation of the absorption spectra of alkali fluorides (for the present only NaF and KF). A short theory of the experiment is given below.

scholarly journals THE ELASTO-VISCOPLASTIC-TIME-DEPENDENT NATURE OF WAXY CRUDE OILS

2014 ◽  
Vol 13 (2) ◽  
pp. 16
Author(s):  
B. A. Tarcha ◽  
B. P. P. Forte ◽  
E. J. Soares ◽  
R. L. Thompson
Keyword(s):  
Yield Stress ◽  
Crude Oils ◽  
Time Dependency ◽  
Gelation Temperature ◽  
Viscous Effects ◽  
Waxy Crude Oil ◽  
Waxy Crude ◽  
Crucial Feature ◽  
Waxy Crude Oils

Production in reservoirs located in deep and ultra-deep water that contain waxy crude oils faces a huge obstacle imposed by the low temperatures of the environment. When the waxy crude oil is subjected to a temperature below the Gelation Temperature, as in the case investigated in the present work, it exhibits a variety of non-Newtonian features: elasticity, plasticity, viscous effects, and time-dependency, which renders to this material a highly complex behavior. A crucial feature that is frequently ignored when the determination of the yield stress is being carried out is the timedependency nature of these materials. We demonstrate that this character has a significant impact on the measurement of the yield stress and, therefore, values obtained from a protocol that neglects time-dependency can be substantially different from a more careful procedure.

scholarly journals Simultaneous determination of procaine hydrochloride, procainamide hydrochloride and lidocaine by molecular absorption spectrometry

2019 ◽  
pp. 318-324
Author(s):  
Nicoleta Mirela Marin ◽  
Gheorghe Batrinescu ◽  
Mihai Nita-Lazar ◽  
Luoana Florentina Pascu ◽  
Carol Blaziu Lehr
Keyword(s):  
Simultaneous Determination ◽  
Direct Method ◽  
Absorption Spectrometry ◽  
Procaine Hydrochloride ◽  
Zero Crossing ◽  
Multicomponent Analysis ◽  
First Derivative ◽  
Cramer’S Rule ◽  
Derivative Spectrometry

Two spectrometric methods have been developed for quantitative simultaneous determination of procaine hydrochloride (PH·HCl), procainamide hydrochloride (PHA·HCl) and lidocaine (Lid) from synthetic mixture. The methods employed are first derivative spectrometry, using zero crossing method and multicomponent analysis which is based on the additivity law. Using first derivative spectrometry, the wavelength selected for the quantitative determination of PH·HCl was 237 nm for Lid was 242 nm and for PHA·HCl was 290 nm in mixture. The method is linear when the concentration ranged between 6.62-9.93 μg/mL for PH·HCl, 6.43-9.64 for PHA·HCl and 5.56-8.35 for Lid. The multicomponent analysis is a direct method and involves the absorbance measurements of at three different wavelengths. The molar absorption coefficients values were calculated at each wavelength and the concentration of PH·HCl, PHA·HCl and Lid from mixture was determined by solving matrix using Cramer's rule. The recovery of each compound in mixture was calculated and it is 101.4 % for PH·HCl, 100.4 % for PHA·HCl and 98.4 % for Lid.

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