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.

Determination of the phase structure of polymerblends by electron microscopy

1978 ◽  
Vol 36 (1) ◽  
pp. 492-493
Author(s):  
Dr. G. Kaemof
Keyword(s):  
Screw Extruder ◽  
Electron Microscopic ◽  
Thin Sections ◽  
Single Screw Extruder ◽  
Transmission Electron ◽  
The Matrix ◽  
Twin Screw ◽  
Special Case ◽  
Microscopic Investigations

A mixture of polycarbonate (PC) and styrene-acrylonitrile-copolymer (SAN) represents a very good example for the efficiency of electron microscopic investigations concerning the determination of optimum production procedures for high grade product properties.The following parameters have been varied:components of charge (PC : SAN 50 : 50, 60 : 40, 70 : 30), kind of compounding machine (single screw extruder, twin screw extruder, discontinuous kneader), mass-temperature (lowest and highest possible temperature).The transmission electron microscopic investigations (TEM) were carried out on ultra thin sections, the PC-phase of which was selectively etched by triethylamine.The phase transition (matrix to disperse phase) does not occur - as might be expected - at a PC to SAN ratio of 50 : 50, but at a ratio of 65 : 35. Our results show that the matrix is preferably formed by the components with the lower melting viscosity (in this special case SAN), even at concentrations of less than 50 %.

Best Practices for Single-Laboratory Validation of Chemical Methods for Trace Elements in Foods. Part I—Background and General Considerations

2013 ◽  
Vol 96 (1) ◽  
pp. 190-203 ◽  
Author(s):  
Cory J Murphy ◽  
James D MacNeil ◽  
Stephen G Capar
Keyword(s):  
Trace Elements ◽  
Best Practices ◽  
Clinical Samples ◽  
Chemical Methods ◽  
Chemical Contaminants ◽  
The Past ◽  
Fit For Purpose ◽  
Single Laboratory ◽  
General Guidance

Abstract The metals subgroup of AOAC INTERNATIONAL's Community on Chemical Contaminants and Residues in Food has been engaged for the past several years in discussions concerning the requirements for the single-laboratory validation (SLV) of methods for the determination of trace elements in foods. This paper reviews the general guidance currently available related to validation of chemical analytical methods and current typical validation practices found in publications on the analysis of elements in food and other matrixes, such as environmental and clinical samples. Based on the available guidance on SLV requirements and a review of current practices in elemental analysis, a general approach based on best practices is proposed for SLV of a method for elements in food to demonstrate the method as “fit-for-purpose.”

An integrated system for wastewater COD characterization and a case study

2010 ◽  
Vol 62 (4) ◽  
pp. 866-874 ◽  
Author(s):  
P. Lu ◽  
X. Zhang ◽  
D. Zhang
Keyword(s):  
Simultaneous Determination ◽  
Membrane Filtration ◽  
Treatment Plant ◽  
Integrated System ◽  
Chemical Methods ◽  
Physical Chemical ◽  
Heterotrophic Biomass ◽  
Raw Wastewater

The guidelines of Activated Sludge Model (ASM) can make the use of modeling more straightforward and systematical. Therefore, this paper aims to develop a guideline for wastewater COD characterization. Four physical-chemical methods were compared experimentally for wastewater characterization in this paper and flocculation + 0.45 μm membrane filtration combining respirometry was selected to determine soluble inert COD. Simultaneous determination of readily and slowly biodegradable COD through respirometric measurement of raw wastewater was proved feasible. In addition, two methods were evaluated to determine heterotrophic biomass. In light of these investigations, an integrated system for characterizing wastewater COD fractions defined in ASM1 was proposed and then applied to characterize influent COD of a treatment plant. By following this guideline, a detailed and practical COD characterization can be obtained. Moreover, this study could also provide an example for the development of more widely accepted guidelines.

The Use of Radioactive Sulfur in Vulcanization

1958 ◽  
Vol 31 (5) ◽  
pp. 1035-1054 ◽  
Author(s):  
G. A. Blokh
Keyword(s):  
Isotopic Exchange ◽  
Radioactive Tracer ◽  
Chemical Methods ◽  
Physical Chemical ◽  
Isotope Method ◽  
Vulcanization Process ◽  
Sulfur Containing ◽  
Structure And Activity ◽  
Made In

Abstract One of the newest and most promising physical-chemical methods consists of the use of radioactive tracer atoms, particularly in such varying fields of knowledge as research, industry, agriculture, etc. It should not be surprising therefore that these methods are favored in the study of rubber, especially in connection with the very complex vulcanization process. The use of the isotope method introduces new, realistic prospects to the experimental study of vulcanization. These include the interaction of sulfur-containing chemicals, such as accelerators, in mixtures subjected to vulcanization. A study of the interaction of accelerators with vulcanizing agents, based on isotopic exchange, makes possible a determination of the mobility of sulfur atoms at carbon-sulfur bonds and other bonds of organic substances. By the isotope method it is possible to observe the movements of sulfur tracer atoms and of tagged sulfur compounds in the complex and manifold curing process. The mobility of sulfur in various combinations with carbon is directly related to accelerator structure and activity and, consequently, to the synthesis of new accelerator types. It is very important to clarify the question as to whether the mobility of sulfur atoms and the intensity of the isotope exchange can serve as a criterion for accelerated activity in curing. Tracer atoms can be used extensively to solve many technological problems in the rubber industry. This review deals with scientific studies made in the field of tagged sulfur vulcanization.

The Petrological Investigation of Roman and Islamic Ceramics from Cyrenaica

1979 ◽  
Vol 10 ◽  
pp. 35-46 ◽  
Author(s):  
J. A. Riley
Keyword(s):  
Traditional Approach ◽  
Routine Practice ◽  
Chemical Methods ◽  
Scientific Methods ◽  
Economic Problems ◽  
The Past ◽  
Preliminary Examination ◽  
Scientific Analysis

The methodology of Mediterranean pottery study (for all periods, but especially for the Roman period) has developed considerably over the past fifteen years, and the range of questions asked of it has been greatly extended. Alongside the traditional approach to pottery studies, which concentrates on typology and chronology, there has been an increasing emphasis on the characterization and determination of the origin of pottery using scientific methods, and also a growing awareness of the importance of pottery quantification (i.e. expressing the relative frequency of different pottery types or styles).It is as a result of these latter two developments that coarse, functional wares can now be used convincingly to complement and greatly extend the economic information provided by fine, decorative wares. Cyrenaica has been in the fore-front of this research (see summary in Humphrey 1979), and it is the purpose of this article to provide a preliminary examination of one aspect, namely the contribution of petrological analysis to our understanding of Cyrenaican local pottery fabrics, and of coarse ware imports.Before a satisfactory typology of pottery from any area can be established, and before that pottery can be used most effectively as evidence for the resolution of economic problems, it is essential that the local fabrics should be recognised. Although visual classification of pottery fabric types is often possible on the basis of subjective factors such as general appearance, texture, hardness, nature of inclusions, etc. (as described in Young in press), there are often problems when attempting to establish their origin. This is normally best done by scientific analysis, using either geological or chemical techniques. It is rapidly becoming the routine practice to analyse fabrics, in the first instance, by geological methods (to identify the major inclusions within the clay), and then, if necessary, by chemical methods (which analyse the elemental composition of the clay).

Immunolocalization of individual filament-forming proteins in the cytoskeleton of Tetrahymena

1990 ◽  
Vol 48 (3) ◽  
pp. 476-477
Author(s):  
Hong Yi ◽  
Norman E. Williams ◽  
Virginia M. Dress ◽  
Kenneth C. Moore
Keyword(s):  
Confocal Microscopy ◽  
Laser Scanning ◽  
Silver Enhancement ◽  
Molecular Weights ◽  
Transmission Electron ◽  
The Individual ◽  
Order Structures

Four polypeptides (tetrins I-IV) have been isolated from the ciliated protozoan Tetrahvmena pyriformis. These polypeptides assemble in vitro into 3-4 nm filaments identical with those present in abundance in a cytoskeletal framework associated with the feeding organelle system (oral apparatus) of this cell type. The polypeptides ranging in molecular weights from 79-89 kDa are not similar to each other in either biochemical or immunological properties. In vivo, the filaments are organized into higher order structures described as cages, cables, and networks. The specific hypothesis arises that the alternate packing arrangements may correlate with different distributions of the individual tetrin polypeptides. We report the production of monoclonal antibodies for each tetrin polypeptide, and the determination of the location of each within the cell using confocal microscopy and immunogold-silver enhancement procedures in conjunction with transmission electron microscopy (TEM).Cell samples for confocal microscopy were labelled according to conventional immunofluorescent procedures and examined with a Bio-Rad MRC-600 laser scanning confocal microscope.

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