Gelation of Rubber Sols by Ultraviolet Light

1946 ◽  
Vol 19 (3) ◽  
pp. 632-644 ◽  
Author(s):  
R. Buckingham ◽  
G. V. Planer
Keyword(s):  
Ultraviolet Light ◽  
Experimental Work ◽  
Carbonyl Compounds ◽  
Theoretical Aspect ◽  
The Other ◽  
Other Hand ◽  
Industrial Manufacture ◽  
Quantitative Results

Abstract On exposure of rubber sols to ultraviolet light in the absence of oxygen, gels known as rubber photogels are formed under certain conditions. It has been found that on removing the solvent the rubber recovered exhibits properties somewhat similar to those obtained on vulcanization. The study of photogelation is of interest, apart from the purely theoretical aspect, because of its possible bearing on the problem of vulcanization, including the various sulfurless vulcanization reactions. Another important aspect is the bearing on the study of the aging of rubber, as well as on the industrial manufacture of rubber cements and solutions. Solvents used in the preparation of photogels are divided into active ones, i.e., those which condense with the rubber on irradiation, and nonactive ones. A number of accelerators are effective in the reaction ; among the most efficient of these are carbonyl compounds Buch as benzophenone, acetone, benzaldehyde, as well as benzoquinone, chloranil, eosin, etc. The nature of the reaction has not hitherto been satisfactorily explained, and a number of widely varying theories have been advanced in the literature. Some investigators regard the reaction as being a polymerization. Pummerer and Kehlen support this view because of the similarity to the photopolymerizations of styrene and isoprene, both of which are favored by the same accelerators as those used in the formation of photogels. Stevens, on the other hand, mentioned cyclization of the rubber molecules as a possible mechanism, and Asano drew attention to the possibility of a stereochemical rearrangement taking place in the molecule on irradiation, producing insolubility. In the experimental work to be described, the reaction was studied by determining the reaction curves under various conditions. As it has frequently been pointed out in the literature that inconsistent quantitative results have been obtained in the study of this reaction, particular importance was attached to developing methods which enabled reproducible results to be obtained.

scholarly journals Analysis of Request for Proposals in Construction Industry

2016 ◽  
Vol 20 (1) ◽  
pp. 104 ◽  
Author(s):  
Michal Tkáč ◽  
Radoslav Delina ◽  
Martina Sabolová
Keyword(s):  
Construction Industry ◽  
Single Case ◽  
The Other ◽  
Pareto Analysis ◽  
Construction Companies ◽  
Potential Client ◽  
Other Hand ◽  
Quantitative Results ◽  
Main Barrier

<p><strong>Purpose:</strong> The purpose of this paper is to identify and determine reasons why construction companies reject some of the request for proposals (RFPS) suitable for them. <br /><strong>Methodology/Approach:</strong> The research has several parts. Within the first part the list of reasons which lead to rejection of RFPS and thus potential client are identified. Then the comparison of differences between groups of rejected RFPS with different configuration is made. The last part of research use Pareto analysis to determine most obvious and most costly reasons of rejection of RFPS. <br /><strong>Findings:</strong> The paper identifies 12 reasons, why construction companies decline to prepare proposal for their potential clients. It also doesn’t confirm that configuration of RFPS has significant impact on the rejection of RFPS. Moreover the results on the other hand showed that insufficient trust represent the main barrier which influences the rejection of RFPS in selected company.<br /><strong>Research Limitation/implication:</strong> The main limitation of the research is that it is based on single case study. Although, the quantitative results have to be generalised very carefully, on the other hand paper provide list of the possible reasons why construction companies decline to compete for an offer. <br /><strong>Originality/Value of paper:</strong> The paper provides unique perspective because apart from traditional attitude, where only the submitted RFPS are evaluated, this paper analyses rejected RFPS and tries to identify and determine reasons why construction companies decide not to prepare proposal and thus reduce the possibility to acquire new contract.</p>

“ Ten Years' Testing of Model Seaplanes ”

1923 ◽  
Vol 27 (149) ◽  
pp. 224-243
Author(s):  
G. S. Baker
Keyword(s):  
Experimental Work ◽  
Royal Society ◽  
General Meeting ◽  
National Physical Laboratory ◽  
The Other ◽  
Experimental Tank ◽  
Know How ◽  
Other Hand ◽  
Physical Laboratory ◽  
Hull Design

An Ordinary General Meeting- of the Society was held at the Royal Society of Arts, on Thursday, February ist, 1923, Professor L. Bairstow in the chair.The Chairman, in opening- the proceedings, said that Mr. G. S. Baker, O.B.E., of the National Physical Laboratory, would deal with flying boats and seaplanes. He would deal with the hull and its design, that part of the seaplane which differentiates it from the aeroplane. That subject had been touched on very lightly by Major Rennie at the previous meeting of the Society, in view of the present paper by Mr. Baker.Mr. Baker had begun work in 1912 on the problems of hull design, at a time when nothing of a definite nature was known; a few individual experiments had been carried out, but there was no systematised knowledge at all at that time. From that state of ignorance a great deal of experimental work had now rescued us. He did not know how far Mr. Baker would stress the point, but it was quite clear, from the investigation of certain accidents to seacraft, that there were fundamental differences in the behaviour of seaplane hulls on the water, differences which had a great deal of effect on the risk of flying-. For instance, if one type of hull was such that when the plane rose in the air it stalled, then all the aerodynamical consequences of stalling- followed, and there was difficulty. On the other hand, it appeared that we had a type of flying- boat which did not make the plane stall on getting into the air, and consequently if it came back to the water it was still controlled. For this type of development, which he believed really dated back to the C.E.i, we were mainly indebted to Mr. Baker and his associates at the National Physical Laboratory, and to the generosity of Sir Alfred Yarrow in placing such a magnificent piece of apparatus as the experimental tank at the disposal of the nation.Mr. Baker then read his paper on “ Ten Years’ Testing of Model Seaplanes.”

scholarly journals Newton as an experimenter

1943 ◽  
Vol 181 (986) ◽  
pp. 244-250
Keyword(s):  
Experimental Work ◽  
Furnace Operation ◽  
The Other ◽  
Theoretical Studies ◽  
Other Hand ◽  
Made In ◽  
Grinding And Polishing ◽  
At Home

The duty has been assigned to me of telling you something about Newton as an experimentalist. As the result of a study of what is known of his history, it seems to me that among his various intellectual pursuits experiment was his first love and the love to which he was most constant. Strange though it be, he seems in some moods to have doubted whether his theoretical studies were worth while, and I do not recall any case where he expressed himself enthusiastically about them. On the other hand, he speaks of his optical work as ‘The oddest if not the most considerable detection which has hitherto been made in the operation of nature.’ Newton loved the mechanical side of experimental work. As a boy he constructed sundials, and, what is more, fixed one of them into the side of the house effectually enough for it to be there a century later. A notebook of his boyhood shows him assiduous in collecting recipes for various kinds of drawing materials, and he notes methods of performing some (rather nasty) conjuring tricks. Later on, when he is making his reflecting telescope, it is obvious that he is a skilled amateur mechanic, at home in furnace operation. He builds his own brick furnace, prepares speculum metal, and is apparently more successful than the professional opticians of the time in grinding and polishing it to a satisfactory spherical figure. (The days of parabolizing were not yet.) It was not until a good many years later that they were able to put such instruments on the market.

Analysis of chromosome movement in crane fly spermatocytes by ultraviolet microbeam irradiation of individual chromosomal spindle fibres. I. General results

1981 ◽  
Vol 59 (9) ◽  
pp. 770-776 ◽  
Author(s):  
Peggy J. Sillers ◽  
Arthur Forer
Keyword(s):  
Ultraviolet Light ◽  
Monochromatic Light ◽  
The Other ◽  
Spindle Fibre ◽  
Chromosome Movement ◽  
Opposite Pole ◽  
Other Hand ◽  
Ultraviolet Microbeam ◽  
The Difference ◽  
Spindle Fibres

Single chromosomal spindle fibres in anaphase Nephrotoma ferruginea (crane fly) spermatocytes were irradiated with monochromatic ultraviolet light focussed to a 4-μm spot by means of an ultraviolet microbeam apparatus. The movement of the half-bivalent associated with the irradiated spindle fibre was either unaffected or the half-bivalent stopped moving; i.e., the effect was all-or-none. When the half-bivalent associated with the irradiated spindle fibre did stop moving, the partner half-bivalent moving towards the opposite pole (i.e., the half-bivalent with which the first half-bivalent was previously paired) also stopped moving: all other half-bivalents moved normally. In over 90% of the 69 cases the movements of the two half-bivalents were only temporarily blocked; when movement resumed both half-bivalents resumed movement at the same time, after stoppage times ranging from 2 min to more than 15 min. In a few cases the half-bivalents never resumed poleward motion.When half-bivalents that had stopped movement finally resumed movement they often did not reach the poles; i.e., they "lagged" and remained separate from the other chromosomes. This result occurred only in spermatocytes of N. ferruginea. In spermatocytes of N. suturalis or N. abbreviata, on the other hand, the stopped half-bivalents did not lag but always reached the poles.Half-bivalent pairs that stopped moving in N. ferruginea spermatocytes did so for shorter times than did those previously reported (after irradiation of chromosomal spindle fibres) in N. suturalis spermatocytes. We suggest that the difference is due to our use of monochromatic ultraviolet light as opposed to the previous use of heterochromatic ultraviolet light. We assume that different wavelengths of monochromatic light produce different effects, that any given monochromatic irradiation produces only one effect (albeit different effects at different wavelengths), but that heterochromatic irradiations can produce multiple effects.Irradiation of the interzone (between separating half-bivalents) had no effect on the chromosome-to-pole movements of the half-bivalents. Therefore the stoppage of movement of half-bivalent pairs is specific for irradiation of chromosomal spindle fibres. On the other hand, irradiation of the interzone often blocked pole-to-pole elongation.

Estimation of Aflatoxin in Corn by “Dockage” Assay

1969 ◽  
Vol 52 (6) ◽  
pp. 1304-1306 ◽  
Author(s):  
Robert M Johnson ◽  
Walter T Greenaway ◽  
William P Dolan
Keyword(s):  
Uv Light ◽  
The Other ◽  
Foreign Material ◽  
Other Hand ◽  
Tlc Plates ◽  
Quantitative Results ◽  
Positive Results ◽  
Ground Corn

Abstract A method of analyzing corn for aflatoxin was developed by assaying only the broken corn, foreign material, and chaff (dockage). Only 1 out of 21 commercial ground corn samples to which corn containing aflatoxin was added gave positive results for aflatoxin. On the other hand, all “Dockage” portions sieved from these same samples gave positive results. The procedure consists of streaking corn extracts on preparative coated sheets for cleanup, separation, and identification. If quantitative results are desired, fluorescent areas are collected and spotted on TLC plates for identification under UV light.

Control of Aeroplanes at Low Speeds

1923 ◽  
Vol 27 (154) ◽  
pp. 473-487
Keyword(s):  
Experimental Work ◽  
The Other ◽  
Research Committee ◽  
General Direction ◽  
Private Person ◽  
Other Hand ◽  
Low Speeds ◽  
Combined Work ◽  
The Way

I must begin by explaining how I come to be giving this lecture. The experimental work with which I shall deal has, for the most part, been done at the N.P.L. and the R.A.E., under the general direction of the Aeronautical Research Committee. The way in which I come to be connected with the work is that I am a member of this Committee and am Chairman of a small panel that was created, some three years ago, by the Committee, to deal with this and other work relating to control and stability. The experiments that I shall describe and the methods of dealing with the results that I shall employ are, therefore, the results of the combined work of a considerable number of people. I can thus claim no special ownership of any of the ideas that I shall use, except in so far as I belong to the panel that has been working upon them. On the other hand I am giving the lecture as a private person, so that any views I express are personal ones and in no sense official.

scholarly journals Associative relations of Serbian adjectives in the free association verbal test

2021 ◽  
Vol 77 (2) ◽  
pp. 185-200
Author(s):  
Milena Jakic-Simsic
Keyword(s):  
Native Speakers ◽  
Free Association ◽  
The Other ◽  
Association Tests ◽  
Parts Of Speech ◽  
Other Hand ◽  
Associative Relation ◽  
Different Ages ◽  
Verbal Test ◽  
Quantitative Results

Previous research on the associative relations of adjectives is not unanimous in terms of whether participants more often respond by using nouns or adjectives in free association tests. On the other hand, when it comes to paradigmatic associative relationships, researchers agree that native speakers respond to adjective stimuli mostly by associations of opposite meaning, but generally do not state the percentage, since conclusions are often made on the basis of the dominant associate, and not upon the entire associative field. Therefore, 45 associative fields of adjectives of the Serbian language are analyzed based on the material obtained from two associative dictionaries, prepared on the basis of the responses of 800 participants (ranging from 18 to 25 years of age) and 1,200 participants of different ages (groups of 5, 9, 13 and 17 years of age, each of which comprised 300 participants). The aim of this study is to examine the ratio of syntagmatic and paradigmatic associations of adjectives, as well as the paradigmatic type of relation between the adjective-type stimuli and their associates (the closeness and the oppositeness of meaning and other types of associative relations). The material was annotated according to parts of speech, as well as according to the types of associative relations. The quantitative results showed that the associations of examined adjectives are slightly more frequently syntagmatic (52%) than paradigmatic (44%), while the oppositeness of meaning proved to be the most common as well as the strongest associative relation of commonly used adjectives of the Serbian language.

A PRELIMINARY EVALUATION OF THE SHALLOW REFLECTION SEISMOGRAPH

Geophysics ◽  
1956 ◽  
Vol 21 (2) ◽  
pp. 388-405 ◽  
Author(s):  
L. C. Pakiser ◽  
R. E. Warrick
Keyword(s):  
Experimental Work ◽  
Colorado Plateau ◽  
The Other ◽  
Preliminary Evaluation ◽  
Mississippi Valley ◽  
Other Hand ◽  
Portage County ◽  
Rock Section

Following successful tests of a specially constructed shallow reflection seismograph in early 1954, new experimental work has been conducted on the Colorado Plateau, in the Upper Mississippi Valley zinc‐lead district, and in Portage County, Ohio. Although reflections were recorded in all of these areas, they were not continuous and correlatable on the Colorado Plateau and in the Upper Mississippi Valley. In Ohio, on the other hand, reflections were recorded from horizons within the Pleistocene overburden as well as from bedrock and horizons within the consolidated rock section. Conditions favoring good reflections are similar for both shallow‐ and deep‐reflection work; they differ only in scale.

Natural photonics for industrial inspiration

2009 ◽  
Vol 367 (1894) ◽  
pp. 1759-1782 ◽  
Author(s):  
Andrew R Parker
Keyword(s):  
Optical Characterization ◽  
Natural World ◽  
The Other ◽  
Other Hand ◽  
Industrial Manufacture ◽  
Optics Industry ◽  
Current Engineering

There are two considerations for optical biomimetics: the diversity of submicrometre architectures found in the natural world, and the industrial manufacture of these. A review exists on the latter subject, where current engineering methods are considered along with those of the natural cells. Here, on the other hand, I will provide a modern review of the different categories of reflectors and antireflectors found in animals, including their optical characterization. The purpose of this is to inspire designers within the $2 billion annual optics industry.

Microhardness Testing, Its Possibilities and Limitations

1960 ◽  
Vol 33 (3) ◽  
pp. 876-889 ◽  
Author(s):  
J. R. Scott ◽  
A. L. Soden
Keyword(s):  
Experimental Work ◽  
Hardness Test ◽  
Standard Test ◽  
The Other ◽  
Test Results ◽  
Good Reproducibility ◽  
Substantial Equivalence ◽  
Other Hand ◽  
Microhardness Testing ◽  
The One

Abstract The need to test small awkwardly shaped rubber articles, which cannot be tested by normal methods, has led to the development of a scaled-down micro test for hardness. Attention is drawn to the mechanical problems that arise in devising such a micro test, especially those associated with friction in the moving parts and with the measurement of the very small movements of the indentor; the various ways in which these problems have been solved are described. The results of experimental work are presented to show the substantial equivalence in readings between the micro and the normal (macro) test, the good reproducibility of micro test results, the influence of testpiece dimensions, and the advantage of using a foot on the instrument as specified in ISO Recommendation R48 for the normal hardness test. Attention is drawn in particular to the influence of the dimensions of the rubber tested, showing on the one hand that reliable hardness measurements can be made, as expected theoretically, on much thinner and smaller specimens than in the standard test, though on the other hand there are minimum dimensions below which even the micro test cannot be expected to give results agreeing strictly with those of the macro test.

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