scholarly journals A convenient method for lactonization of α-allyl esters using iodine in dimethyl- sulphoxide

2014 ◽  
Vol 28 (3) ◽  
pp. 469 ◽  
Author(s):  
B. R. Nawghare ◽  
S. V. Gaikwad ◽  
B. V. Pawar ◽  
P. D. Lokhande
Keyword(s):  
Convenient Method ◽  
Dimethyl Sulphoxide ◽  
Allyl Esters

The application of the Hammett equation to 13C N.M.R. spectroscopy: correlations in the β-nitrostyrenes

1976 ◽  
Vol 29 (12) ◽  
pp. 2607 ◽  
Author(s):  
DAR Happer
Keyword(s):  
Chemical Shift ◽  
Convenient Method ◽  
Experimental Error ◽  
Dimethyl Sulphoxide ◽  
Hammett Equation ◽  
Excellent Correlation ◽  
Substituent Constants ◽  
Hammett Σ Constants

A series of 33 β-nitrostyrenes has been prepared and their 13C N.M.R. spectra have been determined in dimethyl sulphoxide and in deuterochloroform (where soluble). Hammett correlations between substituent and the chemical shift of both the para ring carbons and the α-carbon of the ethenyl group have been shown to be only approximate. In contrast, an excellent correlation has been observed between the chemical shift of the β-carbon of the ethenyl group and Hammett σ+ constants in all cases except those involving para substituents capable of exerting a - R effect. Possible reasons for this are considered. The system appears to be the first reported one where 13C measurements for both meta- and para-substituted compounds give rise to correlations in which agreement lies well inside the limits of experimental error, and shows promise as a convenient method for calculating substituent constants and studying their variation with solvent.

Thickness and composition determinations from T.E.M. specimens using both x-ray and backscattered electron data

1984 ◽  
Vol 42 ◽  
pp. 576-577
Author(s):  
M.D. Ball ◽  
H. Lagace ◽  
M.C. Thornton
Keyword(s):  
Electron Microscope ◽  
Atomic Number ◽  
Transmission Electron Microscope ◽  
Convenient Method ◽  
Flow Chart ◽  
X Ray ◽  
Intensity Measurements ◽  
Transmission Electron ◽  
Electron Intensity ◽  
Backscattered Electron

The backscattered electron coefficient η for transmission electron microscope specimens depends on both the atomic number Z and the thickness t. Hence for specimens of known atomic number, the thickness can be determined from backscattered electron coefficient measurements. This work describes a simple and convenient method of estimating the thickness and the corrected composition of areas of uncertain atomic number by combining x-ray microanalysis and backscattered electron intensity measurements.The method is best described in terms of the flow chart shown In Figure 1. Having selected a feature of interest, x-ray microanalysis data is recorded and used to estimate the composition. At this stage thickness corrections for absorption and fluorescence are not performed.

Stereo imaging in the shadow electron microscope

1978 ◽  
Vol 36 (1) ◽  
pp. 120-121
Author(s):  
W. C. T. Dowell
Keyword(s):  
Electron Microscopy ◽  
Electron Microscope ◽  
Convenient Method ◽  
Patent Application ◽  
Standard Technique ◽  
Stereo Imaging ◽  
Stereo Images ◽  
Specimen Height

Stereo imaging is not new to electron microscopy. Von Ardenne, who first published transmission pairs nearly forty hears ago, himself refers to a patent application by Ruska in 1934. In the early days of the electron microscope von Ardenne employed a pair of magnetic lenses to view untilted specimens but soon opted for the now standard technique of tilting the specimen with respect to the beam.In the shadow electron microscope stereo images can, of course, be obtained by tilting the specimen between micrographs. This obvious method suffers from the disadvantage that the magnification is very sensitive to small changes in specimen height which accompany tilting in the less sophisticated stages and it is also time consuming. A more convenient method is provided by horizontally displacing the specimen between micrographs. The specimen is not tilted and the technique is both simple and rapid, stereo pairs being obtained in less than thirty seconds.

Rotary Beveling for In Situ Thin-Section Microscopy of Cell Cultures

1981 ◽  
Vol 39 ◽  
pp. 550-551
Author(s):  
Dean A. Handley ◽  
Jack T. Alexander ◽  
Shu Chien
Keyword(s):  
Cell Growth ◽  
Cell Cultures ◽  
Molecular Interactions ◽  
Convenient Method ◽  
Petri Dish ◽  
Simple Method ◽  
Thin Section Microscopy ◽  
Thin Sectioning ◽  
Organic Fluids

In situ preparation of cell cultures for ultrastructural investigations is a convenient method by which fixation, dehydration and embedment are carried out in the culture petri dish. The in situ method offers the advantage of preserving the native orientation of cell-cell interactions, junctional regions and overlapping configurations. In order to section after embedment, the petri dish is usually separated from the polymerized resin by either differential cryo-contraction or solvation in organic fluids. The remaining resin block must be re-embedded before sectioning. Although removal of the petri dish may not disrupt the native cellular geometry, it does sacrifice what is now recognized as an important characteristic of cell growth: cell-substratum molecular interactions. To preserve the topographic cell-substratum relationship, we developed a simple method of tapered rotary beveling to reduce the petri dish thickness to a dimension suitable for direct thin sectioning.

A Convenient Method for the Preparation of 1-(Phenylsulfonyl)-1-alkynes

Synlett ◽  
1992 ◽  
Vol 1992 (10) ◽  
pp. 825-826 ◽  
Author(s):  
Martin C. Clasby ◽  
Donald Craig
Keyword(s):  
Convenient Method
Sign in / Sign up

Export Citation Format

Share Document