The Oxidation of Rubber at Atmospheric Temperatures

1931 ◽  
Vol 4 (2) ◽  
pp. 229-238
Author(s):  
W. C. Davey
Keyword(s):  
Acetone Extract ◽  
Similar Form ◽  
Degree Of Cure ◽  
Moist Atmosphere ◽  
Oxidation Rates ◽  
Insoluble Form ◽  
The Difference ◽  
Acetone Extracts ◽  
Very High ◽  
Quartz Tubes

Abstract (1) Oxidation at ordinary temperatures in the dark proceeds very slowly for unextracted rubbers, but at quite a reasonable speed for extracted rubber-sulfur mixings. The rate of oxidation of accelerated mixings, even if acetone-extracted, is very slow. (2) The final increases in weight after long aging are higher at ordinary temperatures than at 70° C. and the amount of acetone extract and the (acetone extract)/(increase in weight) ratios are also very much higher. (3) Storage in a moist atmosphere retards the oxidation in comparison with storage in a dry atmosphere, but the relative rates of oxidation in the two media are dependent on the rubbers under consideration. With slowly oxidizing samples, the lower the degree of cure the less the difference in oxidation rates, but with fast oxidizing rubbers the difference in rates of oxidation in the two media is less if the degree of cure is higher. The amount of acetone extract formed is less during storage in a moist atmosphere than in a dry one. (4) The acetone extract curves show definite maxima due to the change of the extract to insoluble matter, but the tendency for this change is small at atmospheric temperatures. (5) The effect of exposure in sunlight is to cause markedly lower acetone extracts to be obtained than when the samples are stored indoors. Exposed in quartz tubes, the extent of the acetone extract change to insoluble matter is of the order of that at 70° in the dark, and the acetone extract curves are of a similar form. Exposed in glass vessels the degree of extract conversion is not so great as at 70° but very much greater than when the samples are stored indoors. Accelerated mixings exposed in sunlight give very high acetone extracts, indicating that the acetone extracts of such mixings have little tendency to pass into an insoluble form.

The metachor as a characteristic of the association of electrolytes in aqueous solutions

1984 ◽  
Vol 49 (5) ◽  
pp. 1061-1078 ◽  
Author(s):  
Jiří Čeleda ◽  
Stanislav Škramovský
Keyword(s):  
Aqueous Solutions ◽  
Apparent Volume ◽  
Solutions Of Electrolytes ◽  
Molal Volumes ◽  
The Difference ◽  
High Concentrations ◽  
Experimental Values ◽  
Suitable Characteristic ◽  
Association Of Ions ◽  
Very High

Based on the earlier paper introducing a concept of the apparent parachor of a solute in the solution, we have eliminated in the present work algebraically the effect which is introduced into this quantity by the additivity of the apparent molal volumes. The difference remaining from the apparent parachor after substracting the contribution corresponding to the apparent volume ( for which the present authors suggest the name metachor) was evaluated from the experimental values of the surface tension of aqueous solutions for a set of 1,1-, 1,2- and 2,1-valent electrolytes. This difference showed to be independent of concentration up to the very high values of the order of units mol dm-3 but it was directly proportional to the number of the free charges (with a proportionality factor 5 ± 1 cm3 mol-1 identical for all studied electrolytes). The metachor can be, for this reason, a suitable characteristic for detection of the association of ions and formation of complexes in the solutions of electrolytes, up to high concentrations where other methods are failing.

Quality-of-Life Measurement in Advanced Cancer: Assessing the Individual

1999 ◽  
Vol 17 (11) ◽  
pp. 3603-3611 ◽  
Author(s):  
Dympna Waldron ◽  
Ciaran A. O'Boyle ◽  
Michael Kearney ◽  
Michael Moriarty ◽  
Desmond Carney
Keyword(s):  
Quality Of Life ◽  
Advanced Cancer ◽  
Internal Validity ◽  
Semistructured Interview ◽  
Incurable Cancer ◽  
Life Measurement ◽  
The Difference ◽  
The Individual ◽  
Very High

PURPOSE: Despite the increasing importance of assessing quality of life (QoL) in patients with advanced cancer, relatively little is known about individual patient's perceptions of the issues contributing to their QoL. The Schedule for the Evaluation of Individual Quality of Life (SEIQoL) and the shorter SEIQoL–Direct Weighting (SEIQoL-DW) assess individualized QoL using a semistructured interview technique. Here we report findings from the first administration of the SEIQoL and SEIQoL-DW to patients with advanced incurable cancer. PATIENTS AND METHODS: QoL was assessed on a single occasion using the SEIQoL and SEIQoL-DW in 80 patients with advanced incurable cancer. RESULTS: All patients were able to complete the SEIQoL-DW, and 78% completed the SEIQoL. Of a possible score of 100, the median QoL global score was as follows: SEIQoL, 61 (range, 24 to 94); SEIQoL-DW, 60.5 (range, 6 to 95). Psychometric data for SEIQoL indicated very high levels of internal consistency (median r = .90) and internal validity (median R2 = 0.88). Patients' judgments of their QoL were unique to the individual. Family concerns were almost universally rated as more important than health, the difference being significant when measured using the SEIQoL-DW (P = .002). CONCLUSION: Patients with advanced incurable cancer were very good judges of their QoL, and many patients rated their QoL as good. Judgments were highly individual, with very high levels of consistency and validity. The primacy given to health in many QoL questionnaires may be questioned in this population. The implications of these findings are discussed with regard to clinical assessment and advance directives.

scholarly journals Phylogeographic Structure of White Oaks Throughout the European Continent

Genetics ◽  
1997 ◽  
Vol 146 (4) ◽  
pp. 1475-1487 ◽  
Author(s):  
S Dumolin-Lapègue ◽  
B Demesure ◽  
S Fineschi ◽  
V Le Come ◽  
R J Petit
Keyword(s):  
Statistical Approach ◽  
Restriction Analysis ◽  
Phylogeographic Structure ◽  
White Oak ◽  
European Continent ◽  
The Balkans ◽  
Left Behind ◽  
The Difference ◽  
Mantel’S Test ◽  
Very High

Patterns of chloroplast DNA (cpDNA) variation were studied in eight white oak species by sampling 345 populations throughout Europe. The detection of polymorphisms by restriction analysis of PCR-amplified cpDNA fragments allowed the identification of 23 haplotypes that were phylogenetically ordered. A systematic hybridization and introgression between the eight species studied is evident. The levels of subdivision for unordered (G  ST) and ordered (N  ST) alleles are very high and close (0.83 and 0.85). A new statistical approach to the quantitative study of phylogeography is presented, which relies on the coefficients of differentiation G  ST and N  ST and the Mantel's test. Based on pairwise comparisons between populations, the significance of the difference between both coefficients is evaluated at a global and a local scale. The mapped distribution of the haplotypes indicates the probable routes of postglacial recolonization followed by oak populations that had persisted in southern refugia, especially in the Iberian peninsula, Italy and the Balkans. Most cpDNA polymorphisms appear to be anterior to the befinnina of the last recolonization. A subset of the preexisting haplotypes have merely expanded north, while others were left behind in the south.

scholarly journals Hyperfine structure in the arc spectrum of cæsium and nuclear rotation

1928 ◽  
Vol 121 (787) ◽  
pp. 432-447 ◽  
Keyword(s):  
Hyperfine Structure ◽  
Nuclear Spin ◽  
High Frequency ◽  
Principal Series ◽  
Very High Frequency ◽  
Nuclear Rotation ◽  
Higher Temperature ◽  
The Difference ◽  
Mechanical Moment ◽  
Very High

The arc spectrum of cæsium was investigated with the object of finding whether any of its lines possessed hyperfine structure, resulting from a nuclear magnetic moment, due to a quantised nuclear spin. The lines belonging to the principal series should, owing to the greater degree of penetration of the electron in the (1 s or 6 1 ) orbit, and the correspondingly greater interaction, show the greatest effect. The lines of the principal series are very easily broadened if the vapour pressure of the metal becomes high, so that great care had to be used in obtaining the spectrum of cæsium at a sufficiently low temperature. The most satisfactory method of excitation was found to be the application by means of external electrodes of a very high frequency alternating current to a tube filled with helium at about 2 mm. pressure containing a small quantity of cæsium. The tube required slight heating to bring out the cæsium lines; without this the helium spectrum was very much stronger than the metallic spectrum. At a very low vapour pressures of cæsium the discharge was blue in colour. Under these conditions the lines of the principal series showed no broadening greater than that due to thermal agitation, but at a slightly higher temperature the colour of the discharge became purple and the lines broadened. The lines belonging to the principal series were found to be very close doublets with very nearly constant frequencies differences. A theory is worked out which explains the origin of these doublets, assuming a nuclear spin of one half quantum; by correlating the difference in the separation of the hyperfine structure doublets in the 1 s — m 2 p 3/2 lines and the 1 s — m 2 p 1/2 lines, it is shown that a ratio of the magnetic to the mechanical moment of the nucleus about twice as great as the corresponding ratio for the electron would account for the observed frequency differences. The spectral notation used throughout is that of Hund. The results are compared with those found for the hyperfine structure of some of the bismuth lines by Back and Goudsmid, and are found to be in satisfactory agreement. A selection principle is found which applies both to the bismuth and the cæsium spectrum.

scholarly journals Synergistic Interaction of Methanol Extract fromCanarium odontophyllumMiq. Leaf in Combination with Oxacillin against Methicillin-ResistantStaphylococcus aureus(MRSA) ATCC 33591

2016 ◽  
Vol 2016 ◽  
pp. 1-7 ◽  
Author(s):  
Dayang Fredalina Basri ◽  
Vimashiinee Sandra
Keyword(s):  
Inhibitory Concentration ◽  
Methanol Extract ◽  
Bactericidal Effect ◽  
Acetone Extract ◽  
Pharmacodynamic Interaction ◽  
Antistaphylococcal Activity ◽  
Preliminary Study ◽  
Canarium Odontophyllum ◽  
Time Kill ◽  
Acetone Extracts

Canarium odontophyllum(CO) Miq. has been considered as one of the most sought-after plant species in Sarawak, Malaysia, due to its nutritional and pharmacological benefits. This study aimed to evaluate the pharmacodynamic interaction of crude methanol and acetone extracts from CO leaves in combination with oxacillin, vancomycin, and linezolid, respectively, against MRSA ATCC 33591 as preliminary study has reported its potential antistaphylococcal activity. The broth microdilution assay revealed that both methanol and acetone extracts were bactericidal with Minimum Inhibitory Concentration (MIC) of 312.5 μg/mL and 156.25 μg/mL and Minimum Bactericidal Concentration (MBC) of 625 μg/mL and 312.5 μg/mL, respectively. Fractional Inhibitory Concentration (FIC) indices were obtained via the chequerboard dilution assay where methanol extract-oxacillin, acetone extract-oxacillin, methanol extract-linezolid, and acetone extract-linezolid combinations exhibited synergism (FIC index ≤ 0.5). The synergistic action of the methanol extract-oxacillin combination was verified by time-kill analysis where bactericidal effect was observed at concentration of 1/8 × MIC of both compounds at 9.6 h compared to oxacillin alone. As such, these findings postulated that both extracts exert their anti-MRSA mechanism of action similar to that of vancomycin and provide evidence that the leaves ofC. odontophyllumhave the potential to be developed into antistaphylococcal agents.

scholarly journals Has the Propensity to Pay Dividends Declined? Evidence from the US Banking Sector

2021 ◽  
Vol 14 (3) ◽  
pp. 103
Author(s):  
Shaojie Lai ◽  
Qing Wang ◽  
Jiangze Du ◽  
Shuwen Pi
Keyword(s):  
Banking Sector ◽  
Logit Models ◽  
Sample Period ◽  
Financial Firms ◽  
The Us ◽  
The Difference ◽  
High Level ◽  
Propensity To Pay ◽  
Financial Firm ◽  
Very High

This article examines the propensity to pay dividends in the U.S banking sector during 1973–2014. Although the propensity to pay dividends has been declining over the 52 years of our sample period, banks are consistently more likely to pay dividends than non-financial firms. Using the coefficients from logit models estimated early in the sample period to forecast the percentage of dividend payers in each subsequent year, we conclude that there has been a decline in the likelihood of paying dividends in the banking sector. However, the decline started from a very high level as compared to that of the non-banking sectors. In addition, the variables taken from the non-financial firm literature do not explain the difference between the actual and expected percentage of dividend payers in the banking sector. We also conduct exploratory analyses with bank-specific variables. Although newly included variables are significantly related to the likelihood of paying dividends, they do not explain the declining propensity to pay dividends in the banking sector.

The economic and financial viability of sheltered employment centres

2019 ◽  
Vol 57 (9) ◽  
pp. 2261-2283
Author(s):  
Vera Gelashvili ◽  
Eva María Aguilar Pastor ◽  
María-Jesús Segovia-Vargas ◽  
Maria-del-Mar Camacho-Miñano
Keyword(s):  
Training Programs ◽  
Similar Response ◽  
Economic Returns ◽  
Content Type ◽  
Strategic Plans ◽  
Low Levels ◽  
The Difference ◽  
Practical Implications ◽  
Very High

Purpose The purpose of this paper is to investigate whether sheltered employment centers (CEEs) which have a higher rate of professionalization of their managers have better economic returns than those that have a lower one. Design/methodology/approach A questionnaire has been drawn up for their managers. After collecting the answers, an index of professionalization classifies the CEEs with managers of high, medium and low levels of professionalism. This index is then correlated with the main financial ratios of companies. Findings The results show that companies with the highest level of managers’ professionalization, on average, have higher economic returns than companies with medium and low rates, although the difference is not very high. This study is an important contribution to academic literature, as it is the first to examine the professionalization of CEE managers. Research limitations/implications Finally, this paper is not short of limitations. The number of responses is small but there are similar studies with similar response rates. Additionally, the scarcity of responses may suggest that there is a lack of interest about the utility of professionalization by some CEEs managers because, perhaps, they do not have the necessary competences to understand its importance in management. Practical implications This study has some main implications for stakeholders: first, CEEs must pay more attention to the professionalization of their management team, because professionalization can lead to meeting its goals and guaranteeing the firm’s growth. Second, training programs in skills and attitudes should be designed to strengthen these competencies. Moreover, managers of social firms should know that the establishment of strategic plans will be useful to identify new opportunities in the market. Social implications Given the important role of these social firms for the employment of people with disabilities, training programs should be promoted by government in order to ensure the professionalization of these companies. Originality/value This research is an important contribution to the literature on this subject because there are no studies about the level of professionalization of CEEs, companies that represent an important value for the economy of a country.

Comparison of the Bromine and Nitric Acid Methods of Estimating Sulfur in Acetone Extracts

1947 ◽  
Vol 20 (1) ◽  
pp. 315-319 ◽  
Author(s):  
J. F. Morley ◽  
J. R. Scott
Keyword(s):  
Nitric Acid ◽  
Sulfur Content ◽  
Elementary Sulfur ◽  
Total Sulfur ◽  
Total Sulfur Content ◽  
Acid Method ◽  
The Difference ◽  
The One ◽  
Acetone Extracts ◽  
Free Sulfur

Abstract From the experiments described, it appears that neither the bromine method nor the nitric acid method is perfectly satisfactory, for the following reasons. (1) Neither method gives the true free sulfur in rubbers containing sulfur-bearing accelerators, as these cause positive errors of anything up to 0.2–0.3 per cent. (2) The nitric acid method does not give the true free sulfur in rubbers, without sulfur-bearing accelerators, because the result includes some of the sulfur combined with the rubber “resins” the tests do not show definitely whether this applies also to the bromine method. (3) Neither method gives the total sulfur in the acetone extract, since some of the sulfur combined with the “resins” is not included in the result; the presence of certain sulfur-bearing accelerators increases the error. The statement previously referred to (loc. cit.), that the bromine method approximates more nearly to the elementary sulfur content and the nitric acid method more nearly to the total sulfur content of the extract, appears to be a correct generalization. In most cases, however, the difference between the results obtained by the two methods would be less than 0.1 per cent. In respect of simplicity and rapidity of working, the bromine method has the advantage over the nitric acid method, and therefore in all ordinary circumstances is the one to be recommended.

scholarly journals The Difference of Angiopoietin-2 Levels between Dengue Hemorrhagic Fever Patients with Shock and without Shock

2019 ◽  
Vol 7 (13) ◽  
pp. 2119-2122 ◽  
Author(s):  
Rinang Mariko ◽  
Eryati Darwin ◽  
Yanwirasti Yanwirasti ◽  
Sri Rezeki Hadinegoro
Keyword(s):  
Dengue Hemorrhagic Fever ◽  
Sampling Design ◽  
Dengue Infection ◽  
Health Sector ◽  
Hemorrhagic Fever ◽  
Incidence And Mortality ◽  
The Mean ◽  
The Difference ◽  
Angiopoietin 2 ◽  
Very High

BACKGROUND: Dengue infection is one of the problems in the national health sector in Indonesia because the incidence and mortality in Indonesia due to dengue infection is still very high. In 2005 Indonesia became the highest contributor to dengue infection in Southeast Asia (53%) with 95.270 people and 1.298 deaths. AIM: This study aims to analyse differences in angiopoietin-2 levels in dengue hemorrhagic fever (DHF) with and without shock. METHODS: This study was a consecutive sampling design with the research subject was obtained based on the order of admission to the hospital — the serum Angiopoietin-2 levels using the ELISA method. The statistical test used is the independent t-test. The value of p < 0.05 was said to be statistically significant. RESULT: The result showed that the mean of Angiopoietin-2 levels in DHF patients with shock was higher than in DHF (p < 0.05). CONCLUSION: This study concluded that there was a difference in the average level of Angiopoietin-2 among DHF patients with shock compared to without shock.

scholarly journals The Effect of Probabilistic Information on Threshold Forecasts

2007 ◽  
Vol 22 (4) ◽  
pp. 804-812 ◽  
Author(s):  
Susan Joslyn ◽  
Karla Pak ◽  
David Jones ◽  
John Pyles ◽  
Earl Hunt
Keyword(s):  
General Tendency ◽  
Laboratory Setting ◽  
Time Intervals ◽  
Probabilistic Information ◽  
Within Subjects ◽  
Low Probability ◽  
The Difference ◽  
High Winds ◽  
Very High

Abstract The study reported here asks whether the use of probabilistic information indicating forecast uncertainty improves the quality of deterministic weather decisions. Participants made realistic wind speed forecasts based on historical information in a controlled laboratory setting. They also decided whether it was appropriate to post an advisory for winds greater than 20 kt (10.29 m s−1) during the same time intervals and in the same geographic locations. On half of the forecasts each participant also read a color-coded chart showing the probability of winds greater than 20 kt. Participants had a general tendency to post too many advisories in the low probability situations (0%–10%) and too few advisories in very high probability situations (90%–100%). However, the probability product attenuated these biases. When participants used the probability product, they posted fewer advisories when the probability of high winds was low and they posted more advisories when the probability of high winds was high. The difference was due to the probability product alone because the within-subjects design and counterbalancing of forecast dates ruled out alternative explanations. The data suggest that the probability product improved threshold forecast decisions.

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