DETERMINATION OF THE DEGREE OF ORDER OF MESOMORPHIC p-n-ALKOXYBENZOIC ACIDS BY IR DICHROISM METHOD

1975 ◽  
Vol 36 (C1) ◽  
pp. C1-55-C1-57 ◽  
Author(s):  
I. I. KONSTANTINOV ◽  
V. L. KHODZHAEVA ◽  
M. V. SHISHKINA ◽  
Y. B. AMERIK
Keyword(s):  
Ir Dichroism ◽  
Degree Of Order

Feasibility of Molecular Structure Determination With a High Resolution Electron Microscope

1968 ◽  
Vol 26 ◽  
pp. 338-339
Author(s):  
T. A. Welton
Keyword(s):  
Electron Microscope ◽  
Substrate Surface ◽  
Helical Axis ◽  
Base Plane ◽  
Resolution Electron ◽  
High Resolution Electron Microscope ◽  
High Degree ◽  
Degree Of Order ◽  
Purine Pyrimidine

An ultimate design goal for an improved electron microscope, aimed at biological applications, is the determination of the structure of complex bio-molecules. As a prototype of this class of problems, we propose to examine the possibility of reading DNA sequence by an imaginable instrument design. This problem ideally combines absolute importance and relative simplicity, in as much as the problem of enzyme structure seems to be a much more difficult one.The proposed technique involves the deposition on a thin graphite lamina of intact double helical DNA rods. If the structure can be maintained under vacuum conditions, we can then make use of the high degree of order to greatly reduce the work involved in discriminating between the four possible purine-pyrimidine arrangements in each base plane. The phosphorus atoms of the back bone form in projection (the helical axis being necessarily parallel to the substrate surface) two intertwined sinusoids. If these phosphorus atoms have been located up to a certain point on the molecule, we have available excellent information on the orientation of the base plane at that point, and can then locate in projection the key atoms for discrimination of the four alternatives.

scholarly journals AVALIAÇÃO DOS PARÂMETROS TERMODINÂMICOS E CINÉTICOS DE CENOURAS SUBMETIDAS A SECAGEM CONVECTIVA

e-xacta ◽  
2017 ◽  
Vol 10 (2) ◽  
pp. 73 ◽  
Author(s):  
Heloísa Righi Pessoa da Silva ◽  
Roberta Pazinato Cuco ◽  
Barbara Daniele Almeida Porciuncula ◽  
Camila Da Silva
Keyword(s):  
Experimental Data ◽  
Free Energy ◽  
Mathematical Models ◽  
Thermodynamic Parameters ◽  
Kinetic Data ◽  
Temperature Characteristic ◽  
Different Temperatures ◽  
Endothermic Process ◽  
Degree Of Order

<p>Este estudo tem como objetivo a obtenção de dados cinéticos da secagem de cenouras, bem como o ajuste de modelos matemáticos aos dados experimentais e determinação dos parâmetros termodinâmicos do processo. Buscando este propósito, experimentos foram conduzidos em estufa com renovação e circulação de ar, nas temperaturas de 50, 60, 70 e 80 °C. Os modelos matemáticos foram ajustados aos dados das cinéticas de secagem à diferentes temperaturas, e os modelos de Page e de Midilli apresentaram o maior coeficiente de correlação (R<sup>2</sup>) e menor valor de RMSE. Da análise termodinâmica verificou-se que a entalpia e a energia livre de Gibbs diminuíram com o aumento da temperatura, característico de um processo endotérmico. A entropia apresentou valores negativos e diminuiu com a diminuição na temperatura de secagem, isto indica que há um aumento no grau de ordem do sistema, considerado desfavorável entropicamente.</p><p> </p><p>ABSTRACT</p><p>This study aims to obtain kinetic data of carrot drying, as well as the adjustment of mathematical models to the experimental data and determination of the thermodynamic parameters of the process. For this purpose, experiments were conducted in an oven with renovation and circulation of air, at temperatures of 50, 60, 70 and 80 °C. The mathematical models were adjusted to the drying kinetics data at different temperatures, and the Page and de Midilli models presented the highest correlation coefficient (R<sup>2</sup>) and lowest RMSE values. From the thermodynamic analysis it was verified that the enthalpy and the free energy of Gibbs decreased with the increase of the temperature, characteristic of an endothermic process. The entropy presented negative values and decreased with the decrease in the drying temperature, this indicates that there is an increase in the degree of order of the system, considered as entropically unfavorable.</p>

Spectroscopical Investigation of Order-disorder in Some Compounds with Scheelite Structure

1974 ◽  
Vol 29 (5-6) ◽  
pp. 340-346 ◽  
Author(s):  
W. J. Schipper ◽  
G. Blasse
Keyword(s):  
Raman Spectra ◽  
Vibrational Spectra ◽  
Short Range ◽  
Infrared And Raman Spectra ◽  
Scheelite Structure ◽  
Crystallographic Order ◽  
Degree Of Order

Infrared and Raman spectra have been measured of scheelites with formula ALnW8O8, ALnMo2O8 (A = Li, Na, K; Ln = La, Y), Y2MWO8 M = Ge, Si), Y2GeMoO8 and the zircon Y2SiMoO8 in order to get information about the crystallographic order. The A+ and Ln3+ ions in the scheelites ALnW2O8 and ALnMo2O8 are probably ordered in layers Ln-Ln-A-A perpendicular to the c-axis. The order is short-range only. The degree of order decreases in the sequence K, Na, Li. The compounds Y2MWO8 and Y2GeMoO8 are not ordered, whereas the Si4+ and Mo6+ ions in Y2SiMoO8 are ordered in alternate layers perpendicular to the c-axis. The use of vibrational spectra for the determination of crystallographic order is discussed.

Refined Determination of the Structure of Kerogen Etc. by Xrd and its Significance

1995 ◽  
Vol 39 ◽  
pp. 553-560
Author(s):  
Wei Mingxin ◽  
Liu Delian ◽  
Chen Deyu ◽  
Wang Guanxin
Keyword(s):  
Nearest Neighbors ◽  
Computer Programs ◽  
X Ray Diffraction ◽  
Empirical Coefficient ◽  
Experimental Conditions ◽  
X Ray ◽  
Peak Separation ◽  
Aromatic Clusters ◽  
Degree Of Order

The aromaticity fa, crystallite parameters dm, dy, La, Lc, Mc, and RDF parameters r1 and Ka have been determined for sedimentary organic matter, such as kerogens, coals, and bitumens. Here, the rt value is the interatomic distance between the nearest neighbors of carbon atoms, and Ka is an empirical coefficient as an indicator of the degree of order-stacking for aromatic clusters. The refined methods of X-ray diffraction include the improved experimental conditions and new computer programs. The computer programs are composed of four software: AMORPHOUS software; NORMALIZATION software; RDF (Radial Distribution Function) software; and MPS (Multiple Peak Separation) software.

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