Variable-Temperature Study of Syndiotactic Polystyrene

1989 ◽  
Vol 43 (3) ◽  
pp. 440-442 ◽  
Author(s):  
Richard A. Nyquist
Keyword(s):  
Ambient Temperature ◽  
Variable Temperature ◽  
Syndiotactic Polystyrene ◽  
Temperature Study ◽  
Crystalline Forms

IR data are presented which indicate that syndiotactic polystyrene exists in different crystalline forms at ambient temperature, depending upon its physical history.

P.M.R. spectra of heteroaromatic molecules containing bridgehead nitrogen atoms. V. Pyrrolo[a]quinoline

1976 ◽  
Vol 29 (4) ◽  
pp. 847 ◽  
Author(s):  
ML Heffernan ◽  
GM Irvine
Keyword(s):  
Ambient Temperature ◽  
Spin System ◽  
Variable Temperature ◽  
Membered Ring ◽  
Coupling Constants ◽  
Ring Proton ◽  
Temperature Study ◽  
Proton Resonances ◽  
Cdcl3 Solution ◽  
Bridgehead Nitrogen

The p.m.r. spectra of (CD3)2SO and CDCl3 solutions of pyrrolo[a]quinoline, a nine-spin system, have been analysed. In the former case, the various multiplets were sufficiently non-overlapping for detailed double-irradiation experiments to be performed in order to confirm the proton assignments and to determine the magnitudes and relative signs of several inter-ring coupling constants. For the CDCl3 solution, it was found that there was broadening of the five-membered ring proton resonances at ambient temperature. A variable-temperature study showed that the broadening was arising from the exchange of the H1 and H3 protons and that the effects of exchange could be avoided by running the spectra at or below -20�.

scholarly journals Born out of Fire and Ice: Polymorph Studies of the Antiviral Famciclovir

Crystals ◽  
2021 ◽  
Vol 11 (2) ◽  
pp. 129
Author(s):  
Liana Vella-Zarb ◽  
Ulrich Baisch
Keyword(s):  
Variable Temperature ◽  
Chemical Properties ◽  
Crystal Form ◽  
X Ray Diffraction ◽  
Crystal Forms ◽  
X Ray ◽  
Physical Chemical ◽  
Diffraction Patterns ◽  
Crystalline Forms

There is much interest and focus on solid forms of famciclovir. However, in spite of the abundance of reported differences in oral bioavailability, compressibility, and other physical–chemical properties of the various crystal forms of this drug, very little precise structural analysis is available in the literature to date. The form used in the commercial formulation is the anhydrous form I. Patents and patent applications report three different anhydrous crystalline forms on the basis of unindexed powder diffraction patterns. Single-crystal and variable-temperature X-ray diffraction experiments using the commercially available anhydrous form of famciclovir were carried out and led not only to the crystal structure determination of the anhydrous form I, but also to discovery of a new crystal form of anhydrous famciclovir from powder data.

scholarly journals Optimization of Ring Laser Gyroscope Bias Compensation Algorithm in Variable Temperature Environment

Sensors ◽  
2020 ◽  
Vol 20 (2) ◽  
pp. 377
Author(s):  
Jun Weng ◽  
Xiaoyun Bian ◽  
Ke Kou ◽  
Tianhong Lian
Keyword(s):  
Ambient Temperature ◽  
Ring Laser ◽  
Variable Temperature ◽  
Engineering Application ◽  
Output Curve ◽  
Temperature Model ◽  
Temperature Drift ◽  
Derivative Term ◽  
Ring Laser Gyroscope ◽  
Bias Compensation

In a high accuracy strapdown inertial navigation system (SINS), the ring laser gyroscope’s (RLG) bias changes and the performance decreases due to factors in the RLG’s self-heating and changes in ambient temperature. Therefore, it is important to study the bias temperature drift characteristics of RLGs in high, low, and variable temperature environments. In this paper, a composite temperature calibration scheme is proposed. The composite temperature model introduces the derivative term and the temperature derivative cross-multiplier on the basis of the static model and sets the overlap regions for the piecewise least squares fitting. The results show that the composite temperature model can compensate the bias trend term well at ambient temperature, improve the fitting accuracy, and smooth the output curve. The compensation method has a small amount of calculations and flexible parameter design. The precision of the laser gyros in one SINS is improved by about 64.9%, 15.7%, and 3.6%, respectively, which has certain engineering application value.

ATR or transmission—A variable temperature study comparing both techniques using [Fe(3ditz)3](BF4)2 as model system

2016 ◽  
Vol 86 ◽  
pp. 198-205 ◽  
Author(s):  
Danny Müller ◽  
Christian Knoll ◽  
Marco Seifried ◽  
Peter Weinberger
Keyword(s):  
Variable Temperature ◽  
Model System ◽  
Temperature Study

Carbon-13 variable-temperature study of 1-hetero-spiro[2.5]octanes

1985 ◽  
Vol 23 (1) ◽  
pp. 2-6 ◽  
Author(s):  
P. Iratçabal ◽  
M. F. Grenier-Loustalot ◽  
A. Lichanot ◽  
F. Metras
Keyword(s):  
Variable Temperature ◽  
Temperature Study
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