Green Chemistry. Reaction of Elemental Phosphorus (P4) and Elemental Sulfur with Protonodonor Reagents: New Methods for the Synthesis of Ammonium Salts ofS,S′-Dialkyltetrathiophosphoric Acids and Octathiotetraphosphetane

2013 ◽  
Vol 24 (3) ◽  
pp. 163-167 ◽  
Author(s):  
Elvira S. Batyeva ◽  
Elena K. Badeeva ◽  
Elena V. Platova ◽  
Aidar T. Gubaidullin ◽  
Nikki Porch ◽  
...  
Keyword(s):  
Green Chemistry ◽  
Elemental Sulfur ◽  
Ammonium Salts ◽  
Elemental Phosphorus ◽  
New Methods

Mechanism of the Gelling of Hevea Latex by Zinc Compounds

1952 ◽  
Vol 25 (4) ◽  
pp. 995-1005
Author(s):  
G. M. Kraay ◽  
M. van den Tempel
Keyword(s):  
Zinc Oxide ◽  
Reaction Mechanism ◽  
Ammonium Chloride ◽  
Room Temperature ◽  
Ammonium Salts ◽  
Zinc Ions ◽  
Latex Particles ◽  
Zinc Compounds ◽  
New Methods ◽  
Rubber Particles

Abstract Zinc oxide is known to be soluble to a certain extent in ammoniated Hevea latex. The solubility may be enhanced by several means, such as the addition of ammonium salts, and is due to the formation of zinc-ammonia complexes. The complexes themselves have no coagulating power. When heated, however, zinc ions are produced by dissociation of the complexes, and these ions react chemically with the adsorbed soap on the rubber globules, forming an insoluble zinc soap which links up all the rubber globules into a gel. Evidence in favor of the proposed mechanism was obtained by displacing the adsorbed natural higher fat acids of the rubber particles by a soap which does not form an insoluble zinc soap, such as Igepon-T. A latex treated in this manner does not gel when heated with zinc oxide and ammonium chloride at 70° C. By displacing the Igepon-T with ammonium oleate, the original rapid gelation is restored. Depending on the concentration of zinc ions available at room temperature and the amount and types of higher fat acids on the latex particles, thickening or even gelling may occur at room temperature. The above interpretation of the reaction mechanism may lead to new methods for the evaluation of latex.

scholarly journals Green chemistry and polymers made from sulfur

2017 ◽  
Vol 19 (12) ◽  
pp. 2748-2761 ◽  
Author(s):  
Max J. H. Worthington ◽  
Renata L. Kucera ◽  
Justin M. Chalker
Keyword(s):  
Green Chemistry ◽  
Elemental Sulfur ◽  
Polysulfide Polymers

Polysulfide polymers prepared from elemental sulfur have found increasing use in applications that benefit the environment.

Replication of Wet Objects and Cells

1974 ◽  
Vol 32 ◽  
pp. 102-103
Author(s):  
S. Basu ◽  
D. F. Parsons
Keyword(s):  
Water Vapor Pressure ◽  
High Vacuum ◽  
Polystyrene Latex ◽  
Vacuum System ◽  
Saturated Water Vapor ◽  
Replication Method ◽  
New Methods ◽  
Saturated Water ◽  
Water Vapors ◽  
Intermediate Chamber

We are approaching the invasiveness of cancer cells from the studies of their wet surface morphology which should distinguish them from their normal counterparts. In this report attempts have been made to provide physical basis and background work to a wet replication method with a differentially pumped hydration chamber (Fig. 1) (1,2), to apply this knowledge for obtaining replica of some specimens of known features (e.g. polystyrene latex) and finally to realize more specific problems and to improvize new methods and instrumentation for their rectification. In principle, the evaporant molecules penetrate through a pair of apertures (250, 350μ), through water vapors and is, then, deposited on the specimen. An intermediate chamber between the apertures is pumped independently of the high vacuum system. The size of the apertures is sufficiently small so that full saturated water vapor pressure is maintained near the specimen.

A Freeze Shadow Technique for the Preparation of Soft Paint Latexes for Electron Microscopy

1977 ◽  
Vol 35 ◽  
pp. 314-315
Author(s):  
Earl R. Walter ◽  
Glen H. Bryant
Keyword(s):  
Sample Preparation ◽  
High Vacuum ◽  
Vacuum System ◽  
Latex Particles ◽  
New Methods ◽  
Diffusion Pump ◽  
Film Forming ◽  
Routine Basis ◽  
Distribution Studies ◽  
Preparation Techniques

With the development of soft, film forming latexes for use in paints and other coatings applications, it became desirable to develop new methods of sample preparation for latex particle size distribution studies with the electron microscope. Conventional latex sample preparation techniques were inadequate due to the pronounced tendency of these new soft latex particles to distort, flatten and fuse on the substrate when they dried. In order to avoid these complications and obtain electron micrographs of undistorted latex particles of soft resins, a freeze-dry, cold shadowing technique was developed. The method has now been used in our laboratory on a routine basis for several years.The cold shadowing is done in a specially constructed vacuum system, having a conventional mechanical fore pump and oil diffusion pump supplying vacuum. The system incorporates bellows type high vacuum valves to permit a prepump cycle and opening of the shadowing chamber without shutting down the oil diffusion pump. A baffeled sorption trap isolates the shadowing chamber from the pumps.

Scanning Electron Microscope Study of Bacteria on Mineral Surfaces

1976 ◽  
Vol 34 ◽  
pp. 130-131
Author(s):  
V.K. Berry
Keyword(s):  
Oxidation Reaction ◽  
Electron Microscope Study ◽  
Elemental Sulfur ◽  
Thiobacillus Ferrooxidans ◽  
Physical Contact ◽  
Metal Sulfides ◽  
Low Grade ◽  
Mineral Surfaces ◽  
Mineral Surface ◽  
Scanning Electron Microscope Study

There are two strains of bacteria viz. Thiobacillus thiooxidansand Thiobacillus ferrooxidanswidely mentioned to play an important role in the leaching process of low-grade ores. Another strain used in this study is a thermophile and is designated Caldariella .These microorganisms are acidophilic chemosynthetic aerobic autotrophs and are capable of oxidizing many metal sulfides and elemental sulfur to sulfates and Fe2+ to Fe3+. The necessity of physical contact or attachment by bacteria to mineral surfaces during oxidation reaction has not been fairly established so far. Temple and Koehler reported that during oxidation of marcasite T. thiooxidanswere found concentrated on mineral surface. Schaeffer, et al. demonstrated that physical contact or attachment is essential for oxidation of sulfur.

Directional observation on lipid of male nectary of Lindera megaphylla hemsl. by the rapid embedding method with polyethylene glycol (PEG)

1990 ◽  
Vol 48 (3) ◽  
pp. 718-719
Author(s):  
Dai Dalin ◽  
Guo Jianmin
Keyword(s):  
Electron Microscope ◽  
Polyethylene Glycol ◽  
Chemical Reaction ◽  
Traditional Method ◽  
Osmium Tetroxide ◽  
Unsaturated Lipid ◽  
Embedding Method ◽  
Long Period ◽  
New Methods

Lipid cytochemistry has not yet advanced far at the EM level. A major problem has been the loss of lipid during dehydration and embedding. Although the adoption of glutaraldehyde and osmium tetroxide accelerate the chemical reaction of lipid and osmium tetroxide can react on the double bouds of unsaturated lipid to from the osmium black, osmium tetroxide can be reduced in saturated lipid and subsequently some of unsaturated lipid are lost during dehydration. In order to reduce the loss of lipid by traditional method, some researchers adopted a few new methods, such as the change of embedding procedure and the adoption of new embedding media, to solve the problem. In a sense, these new methods are effective. They, however, usually require a long period of preparation. In this paper, we do research on the fiora nectary strucure of lauraceae by the rapid-embedding method wwith PEG under electron microscope and attempt to find a better method to solve the problem mentioned above.

Sign in / Sign up

Export Citation Format

Share Document