Coccal cell-wall compactness and the swelling action of denaturants

1972 ◽  
Vol 18 (5) ◽  
pp. 623-629 ◽  
Author(s):  
Li-Tse Ou ◽  
Robert E. Marquis
Keyword(s):  
Cell Walls ◽  
Weak Interactions ◽  
Polymer Chains ◽  
Urea Solution ◽  
Ion Exchange Resins ◽  
Low Density ◽  
Micrococcus Lysodeikticus ◽  
Exchange Resins ◽  
And Staphylococcus Aureus ◽  
Isolated Cell

Isolated cell walls of Micrococcus lysodeikticus and Staphylococcus aureus were found to have relatively low densities in both the dried and hydrated states. Thus, it appears that the component polymers of these structures do not form crystallites or other highly condensed assemblies, but rather, that their distribution within the wall matrix is similar to that of the polymer chains in low-density, ion-exchange resins. Micrococcus lysodeikticus walls, which are composed mainly of peptidoglycan, swelled significantly when they were heated or transferred to 8 M urea solution. This finding suggests that the compactness of walls and their component peptidoglycans is determined in part by weak interactions that can be disrupted by urea or by heat.

scholarly journals The preparation of iodinated vancomycin and its distribution in bacteria treated with the antibiotic

1970 ◽  
Vol 116 (1) ◽  
pp. 83-92 ◽  
Author(s):  
H. R. Perkins ◽  
M. Nieto
Keyword(s):  
Cell Walls ◽  
Membrane Fraction ◽  
Living Cells ◽  
Differential Absorption ◽  
Micrococcus Lysodeikticus ◽  
Labelled Compound ◽  
Isolated Cell ◽  
Specific Peptide ◽  
Absorption Measurements

Vancomycin was radioactively labelled by iodination with 125I. Iodinated vancomycin was only a little less potent as an antibiotic than vancomycin itself. It was shown, both by chromatography and differential absorption measurements, to combine with acyl-d-alanyl-d-alanine residues. Radioactive vancomycin was used to follow the fate of the antibiotic in bacteria that had been subjected to the least concentration required to inhibit growth. Most of the radioactivity was in the cell walls, although some was found in the membrane fraction. The latter proportion increased during longer incubations with the antibiotic. Pre-formed protoplasts adsorbed very little vancomycin. Mg2+ removed labelled vancomycin from the mucopeptide of Bacillus licheniformis, but had little effect on the antibiotic adsorbed on Micrococcus lysodeikticus, either in vivo or on previously isolated cell walls. Specific peptide was shown to compete with cell walls for vancomycin and it also extracted from cell-wall samples the labelled compound that had been adsorbed on M. lysodeikticus living cells.

Embedding Procedure for Water Swollen Samples

1970 ◽  
Vol 28 ◽  
pp. 504-505
Author(s):  
Ann M. Thomas ◽  
Virginia Shemeley
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Ion Exchange ◽  
Structural Changes ◽  
Cross Linking ◽  
Ion Exchange Resins ◽  
Transmission Electron ◽  
First Pass ◽  
Exchange Resins

Those samples which swell rapidly when exposed to water are, at best, difficult to section for transmission electron microscopy. Some materials literally burst out of the embedding block with the first pass by the knife, and even the most rapid cutting cycle produces sections of limited value. Many ion exchange resins swell in water; some undergo irreversible structural changes when dried. We developed our embedding procedure to handle this type of sample, but it should be applicable to many materials that present similar sectioning difficulties.The purpose of our embedding procedure is to build up a cross-linking network throughout the sample, while it is in a water swollen state. Our procedure was suggested to us by the work of Rosenberg, where he mentioned the formation of a tridimensional structure by the polymerization of the GMA biproduct, triglycol dimethacrylate.

Characterization of machined polystyrene foam

1989 ◽  
Vol 47 ◽  
pp. 372-373
Author(s):  
C. W. Price ◽  
E. F. Lindsey ◽  
R. M. Franks ◽  
M. A. Lane
Keyword(s):  
Surface Finish ◽  
Cell Walls ◽  
Surface Structures ◽  
Efficient Technique ◽  
Low Density ◽  
Polystyrene Foam ◽  
Planar Surfaces ◽  
Machining Characteristics

Diamond-point turning is an efficient technique for machining low-density polystyrene foam, and the surface finish can be substantially improved by grinding. However, both diamond-point turning and grinding tend to tear and fracture cell walls and leave asperities formed by agglomerations of fragmented cell walls. Vibratoming is proving to be an excellent technique to form planar surfaces in polystyrene, and the machining characteristics of vibratoming and diamond-point turning are compared.Our work has demonstrated that proper evaluation of surface structures in low density polystyrene foam requires stereoscopic examinations; tilts of + and − 3 1/2 degrees were used for the stereo pairs. Coating does not seriously distort low-density polystyrene foam. Therefore, the specimens were gold-palladium coated and examined in a Hitachi S-800 FESEM at 5 kV.

Applications of Ion Exchange Resin in Oral Drug Delivery Systems

2017 ◽  
Vol 7 (03) ◽  
Author(s):  
Kathpalia Harsha ◽  
Das Sukanya
Keyword(s):  
Drug Delivery ◽  
Ion Exchange ◽  
Drug Delivery Systems ◽  
Oral Drug Delivery ◽  
Physical Stability ◽  
Delivery Systems ◽  
Oral Drug ◽  
Ion Exchange Resins ◽  
Exchange Resins ◽  
Oral Drug Delivery Systems

Ion Exchange Resins (IER) are insoluble polymers having styrene divinylbenzene copolymer backbone that contain acidic or basic functional groups and have the ability to exchange counter ions with the surrounding aqueous solutions. From the past many years they have been widely used for purification and softening of water and in chromatographic columns, however recently their use in pharmaceutical industry has gained considerable importance. Due to the physical stability and inert nature of the resins, they can be used as a versatile vehicle to design several modified release dosage forms The ionizable drug is complexed with the resin owing to the property of ion exchange. This resin complex dissociatesin vivo to release the drug. Based on the dissociation strength of the drug from the drug resin complex, various release patterns can be achieved. Many formulation glitches can be circumvented using ion exchange resins such as bitter taste and deliquescence. These resins also aid in enhancing disintegrationand stability of formulation. This review focuses on different types of ion exchange resins, their preparation methods, chemistry, properties, incompatibilities and their application in various oral drug delivery systems as well as highlighting their use as therapeutic agents.

THE DISPOSAL OF USED ION EXCHANGE RESINS

2004 ◽  
Vol 3 (3) ◽  
pp. 447-455
Author(s):  
Viky Dicu ◽  
Carmen Iesan ◽  
Mihai Chirica ◽  
Satish Bapat
Keyword(s):  
Ion Exchange ◽  
Ion Exchange Resins ◽  
Exchange Resins

FTIR ANALYSIS OF ION EXCHANGE RESINS WITH APPLICATION IN PERMANENT HARD WATER SOFTENING

2014 ◽  
Vol 13 (9) ◽  
pp. 2145-2152 ◽  
Author(s):  
Liliana Lazar ◽  
Laura Bulgariu ◽  
Bogdan Bandrabur ◽  
Ramona-Elena Tataru-Farmus ◽  
Mioara Drobota ◽  
...  
Keyword(s):  
Ion Exchange ◽  
Hard Water ◽  
Ion Exchange Resins ◽  
Ftir Analysis ◽  
Water Softening ◽  
Exchange Resins

Innovative and sustainable concept of regeneration of decolorization ion exchange resins

2012 ◽  
pp. 381-384 ◽  
Author(s):  
M.A. Theoleyre ◽  
Anne Gonin ◽  
Dominique Paillat
Keyword(s):  
Ion Exchange ◽  
Water Requirement ◽  
Ion Exchange Resins ◽  
Salt Solutions ◽  
Nanofiltration Membranes ◽  
Industrial Efficiency ◽  
Salt Consumption ◽  
Multiple Effect ◽  
Exchange Resins

Regeneration of resins used for decolorization of sugar solutions is done with concentrated salt solutions. Nanofiltration membranes have been proven effective, in terms of industrial efficiency in decreasing salt consumption. More than 90% of the salt that is necessary for regeneration can be recycled through a combination of direct recycling of intermediate eluates, the separation of colored compounds by use of very selective nanofiltration membranes and a multiple-effect evaporation of salty permeates. The desalted color compound solution is sent to the molasses, limiting considerably the effluent to be treated. Starting from a liquor of 800 IU, the water requirement is limited to less than 100 L/t of sugar and the amount of wastewater can be reduced to less than 40 L/t of sugar.

Innovative concepts of regeneration of decolorization ion exchange resins in sugar refineries

2016 ◽  
pp. 377-380
Author(s):  
Marc André Théoleyre ◽  
Anne Gonin ◽  
Dominique Paillat
Keyword(s):  
Ion Exchange ◽  
Reverse Osmosis ◽  
Energy Supply ◽  
Ion Exchange Resins ◽  
Salt Solutions ◽  
Nanofiltration Membranes ◽  
Local Conditions ◽  
Salt Consumption ◽  
Multiple Effect ◽  
Exchange Resins

Regeneration of resins used for decolorization of sugar solutions is done with concentrated salt solutions. Nanofiltration membranes have been proven effective, in terms of industrial efficiency in decreasing salt consumption. More than 90% of the salt that is necessary for regeneration can be recycled through a combination of direct recycling of intermediate eluates, the separation of colored compounds by use of very selective nanofiltration membranes and a system to concentrate salty permeates. According to specific local conditions on energy supply and cost, the concentration of salty permeates can be either a multiple effect evaporator or a combination of electrodialysis and reverse osmosis. The desalted color compound solution is sent to the molasses, limiting considerably the effluent to be treated. Starting from a liquor of 800 IU, the water requirement is limited to less than 100 L/t of sugar and the amount of wastewater can be reduced to less than 40 L/t of sugar.

Extra colour removal in a refinery

2011 ◽  
pp. 718-725 ◽  
Author(s):  
Laura Diego ◽  
Fernando Martín ◽  
Marta G de Quevedo ◽  
Jaime Sagristá
Keyword(s):  
Refining Process ◽  
Ion Exchange Resins ◽  
Colour Removal ◽  
Precipitated Calcium Carbonate ◽  
Sodium Bisulphite ◽  
Powdered Carbon ◽  
Raw Sugar ◽  
Sugar Refinery ◽  
Exchange Resins ◽  
Main Factor

The main factor affecting the raw sugar refining process is certainly “colour”. The higher colour removal, the higher is the obtained sugar yield. Therefore, colour removal is the main goal throughout the process. In a conventional sugar refinery colour is removed in the purification and decolorisation steps – the second one is normally done using ion-exchange resins – but there are some other ways of colour removal such as adding some colour removing agents (powdered carbon, sodium bisulphite, PCC [precipitated calcium carbonate]). In this article the pilot plant results of experiments of increasing colour removal in the refining process are described, such as PCC addition, 3rd carbonatation (re-purification), hydrogen peroxide addition, powdered carbon addition, sodium bisulphite addition and crystallization improvements. The good results achieved in some of these trials led to perform some industrial trials, the results of wich are summarized in this article as well.

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