ALKOXIDES OF VANADIUM (IV)

1962 ◽  
Vol 40 (6) ◽  
pp. 1183-1188 ◽  
Author(s):  
D. C. Bradley ◽  
M. L. Mehta
Keyword(s):  
Molecular Weights ◽  
New Compounds ◽  
Titanium Compounds

A number of tetraalkoxides of vanadium (IV) have been prepared by alcoholysis of tetrakis(diethylamino)vanadium (IV). Volatilities and molecular weights were determined on the new compounds and compared with the properties of the corresponding titanium compounds. Some of the primary alkoxides of vanadium are polymeric and this polymerization affects not only the volatility but also the color of the compound.

scholarly journals N-Disilanyl-phosphinimine, Darstellung und Eigenschaften / N-Disilanyl-phosphine Imines, Preparation and Properties

1975 ◽  
Vol 30 (11-12) ◽  
pp. 907-913 ◽  
Author(s):  
Werner Wolfsberger
Keyword(s):  
Elemental Analysis ◽  
Nmr Spectra ◽  
Ir And Nmr Spectra ◽  
Molecular Weights ◽  
Tertiary Phosphines ◽  
New Compounds

Several routes for the synthesis of N-pentamethyldisilanylphosphine imines have been investigated. The title compounds may be prepared by methylation of N-(2-chlorodisilanyl)-phosphine imines, from tertiary phosphines and pentamethyldisilanyl azide, from triorganophosphine imines and pentamethyldisilanyl chloride, or, by transsilylation, from the corresponding N-trimethylsilylphosphine imines. 22 new compounds were characterized by elemental analysis, molecular weights, IR and NMR spectra.

Reactions of Amino-imino-boranes with Transition Metal Halides and Substituted Transition Metal Halides

2001 ◽  
Vol 56 (7) ◽  
pp. 659-670 ◽  
Author(s):  
Barbara Böck ◽  
Heinrich Nöth ◽  
Ulrich Wietelmann
Keyword(s):  
Transition Metal ◽  
The Other ◽  
Metal Halides ◽  
Other Hand ◽  
New Compounds ◽  
Hydrolysis Of ◽  
Cl Atoms ◽  
Titanium Compounds

The aminoiminoborane tmp-B=NCMe3 (1) adds to TiBr4 or ZrCl4 in a 1:1 ratio while PdCl2 adds 1 in a 1:2 ratio. In these new compounds the NBN unit is almost linear and the configuration corresponds to an allene. On the other hand 1 and Ti(OR)4 compounds and Ti(NMe2)4 give N metallated diaminoboranes tmp-B(X)-NCMe3EX3 (X = OR, NMe2). Mixed compounds Ti(OR)3-nXn lead to diaminoboranes with BOR groups while the TiCl bond inserts into the B = N bond of 1 to produce tmp-BNMe2-NCMe3TiCl3. Hydrolysis of this compound leads to a spirocyclic dititanoxane with a short linear Ti-O-Ti bond and pentacoordinated Ti centers carrying two Cl atoms each. Spirocycles with a BN2E (E = Ti, Nb, Ta, Pd) unit are formed when 1 is allowed to react with TiCl4, NbCl5, TaCl5 and PdCl2. The palladium compound 16 is dimeric, and dimerization occurs via Pd-Cl bridges. The aminoiminoborane tmp-B=NC6H3-2,6-iPr2 reacts with the titanium compounds in the same manner as 1, however without formation of spirocycles.

Transmission Electron Microscopy of Protein Macromolecules

1971 ◽  
Vol 29 ◽  
pp. 424-425
Author(s):  
Henry S. Slayter
Keyword(s):  
Biological Systems ◽  
Metal Vapor ◽  
Resolving Power ◽  
Electron Microscopic ◽  
Chemical Methods ◽  
Molecular Weights ◽  
The Past ◽  
Physical Chemical ◽  
Transmission Electron

Electron microscopic methods have been applied increasingly during the past fifteen years, to problems in structural molecular biology. Used in conjunction with physical chemical methods and/or Fourier methods of analysis, they constitute powerful tools for determining sizes, shapes and modes of aggregation of biopolymers with molecular weights greater than 50, 000. However, the application of the e.m. to the determination of very fine structure approaching the limit of instrumental resolving power in biological systems has not been productive, due to various difficulties such as the destructive effects of dehydration, damage to the specimen by the electron beam, and lack of adequate and specific contrast. One of the most satisfactory methods for contrasting individual macromolecules involves the deposition of heavy metal vapor upon the specimen. We have investigated this process, and present here what we believe to be the more important considerations for optimizing it. Results of the application of these methods to several biological systems including muscle proteins, fibrinogen, ribosomes and chromatin will be discussed.

Characterization of microtubules by dark-field STEM and replication

1991 ◽  
Vol 49 ◽  
pp. 152-153
Author(s):  
S.B. Andrews ◽  
R.D. Leapman ◽  
P.E. Gallant ◽  
T.S. Reese
Keyword(s):  
Protein Interactions ◽  
Low Dose ◽  
Unit Length ◽  
Dark Field ◽  
Carbon Films ◽  
Microtubule Associated Proteins ◽  
Molecular Weights ◽  
Freeze Dried ◽  
Protein Motors ◽  
Associated Proteins

As part of a study on protein interactions involved in microtubule (MT)-based transport, we used the VG HB501 field-emission STEM to obtain low-dose dark-field mass maps of isolated, taxol-stabilized MTs and correlated these micrographs with detailed stereo images from replicas of the same MTs. This approach promises to be useful for determining how protein motors interact with MTs. MTs prepared from bovine and squid brain tubulin were purified and free from microtubule-associated proteins (MAPs). These MTs (0.1-1 mg/ml tubulin) were adsorbed to 3-nm evaporated carbon films supported over Formvar nets on 600-m copper grids. Following adsorption, the grids were washed twice in buffer and then in either distilled water or in isotonic or hypotonic ammonium acetate, blotted, and plunge-frozen in ethane/propane cryogen (ca. -185 C). After cryotransfer into the STEM, specimens were freeze-dried and recooled to ca.-160 C for low-dose (<3000 e/nm2) dark-field mapping. The molecular weights per unit length of MT were determined relative to tobacco mosaic virus standards from elastic scattering intensities. Parallel grids were freeze-dried and rotary shadowed with Pt/C at 14°.

Electron Microscope Study of RNA's of Paramyxoviruses

1972 ◽  
Vol 30 ◽  
pp. 196-197
Author(s):  
Ruchama Baum ◽  
J.T. Seto
Keyword(s):  
Electron Microscopy ◽  
Electron Microscope ◽  
Electron Microscope Study ◽  
Sendai Virus ◽  
Sodium Dodecyl ◽  
Rna Molecules ◽  
Virus Particles ◽  
Molecular Weights ◽  
Length Measurements

The ribonucleic acid (RNA) of paramyxoviruses has been characterized by biochemical and physiochemical methods. However, paramyxovirus RNA molecules have not been studied by electron microscopy. The molecular weights of these single-stranded viral RNA molecules are not known as yet. Since electron microscopy has been found to be useful for the characterization of single-stranded RNA, this investigation was initiated to examine the morphology and length measurements of paramyxovirus RNA's.Sendai virus Z strain and Newcastle disease virus (NDV), Milano strain, were used. For these studies it was necessary to develop a method of extracting RNA molecules from purified virus particles. Highly purified Sendai virus was treated with pronase (300 μg/ml) at 37°C for 30 minutes and the RNA extracted by the sodium dodecyl sulfate (SDS)-phenol procedure.

Nucleic Acid Molecules Prepared by Monolayer Techniques

1972 ◽  
Vol 30 ◽  
pp. 178-179
Author(s):  
Dimitrij Lang
Keyword(s):  
Electron Microscopy ◽  
Standard Deviation ◽  
Nucleic Acid ◽  
Cytochrome C ◽  
Nucleic Acids ◽  
Contour Length ◽  
Sample Standard Deviation ◽  
Molecular Weights ◽  
Length Measurements ◽  
Protein Monolayer

The success of the protein monolayer technique for electron microscopy of individual DNA molecules is based on the prevention of aggregation and orientation of the molecules during drying on specimen grids. DNA adsorbs first to a surface-denatured, insoluble cytochrome c monolayer which is then transferred to grids, without major distortion, by touching. Fig. 1 shows three basic procedures which, modified or not, permit the study of various important properties of nucleic acids, either in concert with other methods or exclusively:1) Molecular weights relative to DNA standards as well as number distributions of molecular weights can be obtained from contour length measurements with a sample standard deviation between 1 and 4%.

Crystal chemistry of high-Tc superconductors

1990 ◽  
Vol 48 (4) ◽  
pp. 1118-1119
Author(s):  
Maryvonne Hervieu
Keyword(s):  
Oxygen Deficiency ◽  
Large Family ◽  
Copper Oxides ◽  
High Tc Superconductors ◽  
High Tc ◽  
Single Mechanism ◽  
Square Planar ◽  
History Of ◽  
Bismuth Cuprates ◽  
New Compounds

Four years after the discovery of superconductivity at high temperature in the Ba-La-Cu-O system, more than thirty new compounds have been synthesized, which can be classified in six series of copper oxides: La2CuO4 - type oxides, bismuth cuprates, YBa2Cu3O7 family, thallium cuprates, lead cuprates and Nd2CuO4 - type oxides. Despite their quite different specific natures, close relationships allow their structures to be simply described through a single mechanism. The fifth first families can indeed be described as intergrowths of multiple oxygen deficient perovskite slabs with multiple rock salt-type slabs, according to the representation [ACuO3-x]m [AO]n.The n and m values are integer in the parent structures, n varying from 0 to 3 and m from 1 to 4; every member of this large family can thus be symbolized by [m,n]. The oxygen deficient character of the perovskite slabs involves the existence or the co-existence of several types of copper environment: octahedral, pyramidal and square planar.Both mechanisms, oxygen deficiency and intergrowth, are well known to give rise easily to nonstoichiometry phenomena. Numerous and various phenomena have actually been characterized in these cuprates, strongly depending on the thermal history of the samples.

Evaluation of New Compounds for Opioid Activity: Annual Report (1993)

1994 ◽  
Author(s):  
J. C. Woods ◽  
◽  
C. P. France ◽  
F. Medzihradsky ◽  
C. B. Smith ◽  
...  
Keyword(s):  
Annual Report ◽  
Opioid Activity ◽  
New Compounds
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