The Structure of Papaverine in Solution as Determined by 1H Nuclear Magnetic Relaxation Methods

1987 ◽  
Vol 40 (5) ◽  
pp. 915 ◽  
Author(s):  
ID Rae ◽  
ID Rae ◽  
PM Simmonds ◽  
PM Simmonds
Keyword(s):  
Magnetic Relaxation ◽  
Torsional Angle ◽  
Relaxation Methods ◽  
Conformational Energy Calculations ◽  
Related Alkaloid ◽  
Cdcl3 Solution ◽  
13C Relaxation ◽  
Noesy Spectra ◽  
Broad Energy ◽  
Good Agreement

Hydrogen relaxation in the papaverine molecule in CDCl3 solution has been studied so as to derive the conformation about the C1-CH2 bond. This was done for papaverine itself, in which the resonances of H5 and H8 were reassigned on the basis of NOESY spectra, and in the 7-OC2H3 analogue, the spectrum of which confirms the reassignment. The value for the torsional angle C 8a-C1-CH2-C lays between 70 and 92�, in good agreement with those found in crystals of papaverine , its hydrochloride, and the related alkaloid isosevanine (all in the range 68-94�). Conformational energy calculations show a broad energy minimum over the range 60-70�. The 6,7-methylenedioxy analogue of papaverine has essentially the same conformation but tumbles more rapidly in solution, the Tc value for it being 1.9×10-1ls whereas values for papaverine were 5.6×10-11 s (from 1H relaxation) and 3.1×1011 s (from 13C relaxation).

scholarly journals Alignment of Dust Grains by Magnetic Relaxation: A Comparison Between Results Obtained by Two Different Methods

1973 ◽  
Vol 52 ◽  
pp. 187-189
Author(s):  
P. Cugnon
Keyword(s):  
Monte Carlo ◽  
Monte Carlo Method ◽  
Magnetic Relaxation ◽  
Planck Equation ◽  
Dust Grains ◽  
Fokker Planck Equation ◽  
The Monte Carlo Method ◽  
Good Agreement ◽  
Fokker Planck

This paper is devoted to a comparison between results obtained by Purcell and Spitzer (1971) using a Monte-Carlo method and by the author (1971) using a Fokker-Planck equation. It is shown that there is a good agreement between the results within the dispersion expected from the Monte-Carlo method.

A study of internal rotation in 2-furaldehyde through 13C relaxation times in the rotating frame

1987 ◽  
Vol 52 (2) ◽  
pp. 541-546 ◽  
Author(s):  
Vladimír Mlynárik
Keyword(s):  
Shape Analysis ◽  
Line Shape ◽  
Activation Enthalpy ◽  
Relaxation Times ◽  
Rotating Frame ◽  
Line Shape Analysis ◽  
13C Relaxation Times ◽  
Free Activation Energy ◽  
13C Relaxation ◽  
Good Agreement

Carbon-13 relaxation times in the rotating frame were used to study the exchange between unequally populated rotamers of 2-furaldehyde. Calculated free activation energy and activation enthalpy are in good agreement with the results of 1H line shape analysis. Accuracy and reliability of this method in comparison with the line shape analysis is discussed.

Relaxation Methods for Nonlinear Dynamics and Hysteresis Operators

1999 ◽  
Author(s):  
A. Kurdila ◽  
J. Li
Keyword(s):  
Nonlinear Dynamics ◽  
Structural Systems ◽  
Relaxed Controls ◽  
Dynamical Models ◽  
Active Materials ◽  
Relaxation Methods ◽  
Dynamic Hysteresis ◽  
Identification Theory ◽  
Hysteresis Operators ◽  
Good Agreement

Abstract Previous research has demonstrated that rigorous modeling and identification theory can be derived for structural dynamical models that incorporate control influence operators that are static Krasnoselskii-Pokrovskii integral hysteresis operators. Experimental evidence likewise has shown that some dynamic hysteresis models provide more accurate representations of a class of structural systems actuated by some active materials including shape memory alloys and piezoceramics. In this paper, we show that the representation of control influence operators via static hysteresis operators can be interpreted in terms of a homogeneous Young’s measure. Within this framework, we subsequently derive dynamic hysteresis operators represented in terms of Young’s measures that are parameterized in time. We show that the resulting integrodifferential equations are similar to the class of relaxed controls discussed by Warga [10], Garnkrelidze [24], and Roubicek [25]. The formulation presented here differs from that studied in [10], [24] and [25] in that the kernel of the hysteresis operator is a history dependent functional, as opposed to Caratheodory integral satisfying a growth condition. The theory presented provides representations of dynamic hysteresis operators that have provided good agreement with experimental behavior in some active materials.

Oscillator Strength Measurements in the Vacuum-Ultraviolet by the Emission Method

1988 ◽  
Vol 102 ◽  
pp. 353-356
Author(s):  
C. Goldbach ◽  
G. Nollez
Keyword(s):  
Oscillator Strength ◽  
Vacuum Ultraviolet ◽  
Oscillator Strengths ◽  
Emission Method ◽  
Absolute Scale ◽  
Good Agreement

AbstractThe principles and the realization of an experiment devoted to oscillator strength measurements in the vacuum-ultraviolet by the emission method are briefly presented. The results obtained for the strong multiplets of neutral nitrogen and carbon in the 1200-2000 Å range yield an absolute scale of oscillator strengths in good agreement with the most recent calculations.

A High Voltage Electron Microscopy Study of Sub-Oxide Formation in Vanadium

1971 ◽  
Vol 29 ◽  
pp. 212-213
Author(s):  
R. H. Geiss ◽  
R. L. Ladd ◽  
K. R. Lawless
Keyword(s):  
High Vacuum ◽  
Microscopy Study ◽  
Electron Microscopy Study ◽  
Ultra High Vacuum ◽  
Pure Oxygen ◽  
Pressure Oxidation ◽  
High Voltage Electron Microscopy ◽  
Oxidation Study ◽  
Voltage Electron ◽  
Good Agreement

Detailed electron microscope and diffraction studies of the sub-oxides of vanadium have been reported by Cambini and co-workers, and an oxidation study, possibly complicated by carbon and/or nitrogen, has been published by Edington and Smallman. The results reported by these different authors are not in good agreement. For this study, high purity polycrystalline vanadium samples were electrochemically thinned in a dual jet polisher using a solution of 20% H2SO4, 80% CH3OH, and then oxidized in an ion-pumped ultra-high vacuum reactor system using spectroscopically pure oxygen. Samples were oxidized at 350°C and 100μ oxygen pressure for periods of 30,60,90 and 160 minutes. Since our primary interest is in the mechanism of the low pressure oxidation process, the oxidized samples were cooled rapidly and not homogenized. The specimens were then examined in the HVEM at voltages up to 500 kV, the higher voltages being necessary to examine thick sections for which the oxidation behavior was more characteristic of the bulk.

Diagnostic Value of Electron Microscopy in Soft Tissue Tumors

1970 ◽  
Vol 28 ◽  
pp. 220-221
Author(s):  
Gerald Fine ◽  
Azorides R. Morales
Keyword(s):  
Cardiac Myxoma ◽  
Osteogenic Sarcoma ◽  
Diagnostic Value ◽  
Soft Tissue Tumors ◽  
Amelanotic Melanoma ◽  
Growth Patterns ◽  
Light Microscopic Level ◽  
Mesenchymal Tumors ◽  
Good Agreement

For years the separation of carcinoma and sarcoma and the subclassification of sarcomas has been based on the appearance of the tumor cells and their microscopic growth pattern and information derived from certain histochemical and special stains. Although this method of study has produced good agreement among pathologists in the separation of carcinoma from sarcoma, it has given less uniform results in the subclassification of sarcomas. There remain examples of neoplasms of different histogenesis, the classification of which is questionable because of similar cytologic and growth patterns at the light microscopic level; i.e. amelanotic melanoma versus carcinoma and occasionally sarcoma, sarcomas with an epithelial pattern of growth simulating carcinoma, histologically similar mesenchymal tumors of different histogenesis (histiocytoma versus rhabdomyosarcoma, lytic osteogenic sarcoma versus rhabdomyosarcoma), and myxomatous mesenchymal tumors of diverse histogenesis (myxoid rhabdo and liposarcomas, cardiac myxoma, myxoid neurofibroma, etc.)

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