Two Modes of Action of Antioxidants in Rubber

1945 ◽  
Vol 18 (1) ◽  
pp. 22-23 ◽  
Author(s):  
Jean Le Bras
Keyword(s):  
Systematic Study ◽  
Base Composition ◽  
Chemical Compositions ◽  
Rubber Mixture ◽  
Modes Of Action ◽  
Other Substances ◽  
Harmful Effects

Abstract It is a commonly accepted belief that antioxidants protect oxidizable products from the harmful effects of oxygen by retarding the rate at which these oxidizable products combine with oxygen. Consequently, if the oxidizability of a rubber mixture containing no antioxidant and the oxidizability of the same mixture to which such an agent has been added are measured under the same conditions, the absorption of oxygen would be expected to be distinctly less rapid in the second case. This has, in fact, been proved to be true in general, not only for rubber, but also for other substances which are protected by antioxidants. In a systematic study of a series of antioxidants of differing chemical compositions, various observations were made which gave indications that these products react in two different ways. In these experiments a rubber mixture of chosen composition was prepared as a blank or control, and was compared with other mixtures of the same base composition to which various antioxidants selected for study had been added in the same proportion in all cases.

A Review on Regulatory Aspects of Food Contact Materials (FCM’S)

2018 ◽  
Vol 55 (4) ◽  
pp. 500
Author(s):  
V. S. Deepika Rani ◽  
R. Naveen Kumar ◽  
Sudershan Rao Vemula
Keyword(s):  
Food Safety ◽  
Scientific Evidence ◽  
Scientific Information ◽  
Primary Objective ◽  
Contact Materials ◽  
Food Contact Materials ◽  
Food Contact ◽  
Safeguard Measures ◽  
Other Substances ◽  
Harmful Effects

Since the advent of commercial production of Food Contact Materials (FCM) and their extensive use in day to day life, many harmful effects on health were reported to be caused due to ingestion of food contaminated with constituents that migrated from FCM. Over the years, this aspect of food safety from FCM rose to be an important research interest and thus added scientific information on FCM. Based on the scientific evidence and new issues being raised (E.g. BPA replaced by other substances), these regulations are also being molded from time to time across the world. Therefore this review aims at providing an overview of regulations and amendments on FCM in various countries with emphasis on important aspects (e.g. traceability and safeguard measures of EU framework regulations, Food contact notification of USFDA, etc.) in FCM laws. Hereunder, for a better understanding of these regulations, various countries reviewed in this article are grouped into 3 categories, i.e. – countries having 1) specific regulations 2) Non- specific/ few regulations 3) No data available on FCM regulations. Though these regulations differed from one country to other, all were formulated with a primary objective, of ensuring consumer food safety. This review will not only help in ensuring food safety but also helps in, to strengthen regulatory framework and grow in trade, fulfilling the gaps with global FCM regulations.

scholarly journals Recent Advancements in the Nanomaterial Application in Concrete and Its Ecological Impact

Materials ◽  
2021 ◽  
Vol 14 (21) ◽  
pp. 6387
Author(s):  
Haleema Saleem ◽  
Syed Javaid Zaidi ◽  
Nasser Abdullah Alnuaimi
Keyword(s):  
Ecological Impact ◽  
Research Area ◽  
Chemical Compositions ◽  
Mechanical And Thermal Properties ◽  
Nano Tio2 ◽  
Construction Waste ◽  
Nanosized Materials ◽  
Significant Research ◽  
Harmful Effects ◽  
Study Development

At present, nanotechnology is a significant research area in different countries, owing to its immense ability along with its economic impact. Nanotechnology is the scientific study, development, manufacturing, and processing of structures and materials on a nanoscale level. It has tremendous application in different industries such as construction. This study discusses the various progressive uses of nanomaterials in concrete, as well as their related health risks and environmental impacts. Nanomaterials such as nanosilica, nano-TiO2, carbon nanotubes (CNTs), ferric oxides, polycarboxylates, and nanocellulose have the capability to increase the durability of buildings by improving their mechanical and thermal properties. This could cause an indirect reduction in energy usage and total expenses in the concrete industry. However, due to the uncertainties and irregularities in size, shape, and chemical compositions, some nanosized materials might have harmful effects on the environment and human health. Acknowledgement of the possible beneficial impacts and inadvertent dangers of these nanosized materials to the environment will be extremely important when pursuing progress in the upcoming years. This research paper is expected to bring proper attention to the probable effects of construction waste, together with the importance of proper regulations, on the final disposal of the construction waste.

scholarly journals A systematic study of stellar models for C/O-rich Wolf-Rayet Stars

1988 ◽  
Vol 108 ◽  
pp. 92-91
Author(s):  
N. Langer ◽  
M. Kiriakidis
Keyword(s):  
Chemical Composition ◽  
Systematic Study ◽  
Effective Temperature ◽  
Mass Range ◽  
Stellar Mass ◽  
Stellar Structure ◽  
Chemical Compositions ◽  
Helium Stars ◽  
Pure Helium ◽  
Stellar Models

A grid of homogeneous stellar models for Wolf-Rayet stars in the mass range from 1 to 60 M⊙ has been computed. For each stellar mass, stars with eight different sets of chemical compositions — from pure helium stars with (Y,C,O)=(1,0,0) to extreme helium poor stars with (Y,C,O)=(0.02,0.11,0.87) — have been calculated in order to investigate the dependence of the stellar structure on the stellar mass and chemical composition. Modern input physics adapted to the exotic chemical composition of the Wolf-Rayet stars has been incorporated in the models, including effects of partial recombination of helium, carbon, and oxygen, and detailed opacity tables for 20 different combinations of the (Y,C,O)-abundances. Furthermore, we estimated the effect of the intense, partly optically thick Wolf-Rayet winds on their apparent effective temperature, using the formalism of de Loore et al. (1982, IAU-Symp. 99, 53) with the parameters: = 3 . 10−5M⊙yr−1, β = 2, and v∞ = 2000 km s−1.

Contributions to the Analysis of Rubber. III. Determination of Copper in Raw Rubber, in Mixtures, and in Fillers

1938 ◽  
Vol 11 (4) ◽  
pp. 706-715
Author(s):  
P. Dekker
Keyword(s):  
Copper Content ◽  
Harmful Effect ◽  
Allowable Limit ◽  
Rubber Mixture ◽  
Copper Compounds ◽  
Decisive Importance ◽  
Harmful Effects ◽  
Determination Of Copper ◽  
Rubber Article

Abstract It is already well known that copper compounds have an extremely harmful effect on rubber articles. Since, however, very small quantities of copper are always present in fillers, in fact, in compounding ingredients in general and even in ordinary plantation rubber itself, it is not possible to manufacture a rubber article which is free of copper. In view of this, one must be content in each case with keeping the copper content within a certain allowable limit. However, it has been found that not only is the quantity of copper of decisive importance, but that still other factors play a part in the harmful effects brought about by the copper. Attention has been called repeatedly in the literature to the fact that copper compounds which are injurious are those which dissolve in the rubber mixture. Nevertheless, it is certain that the harmful effects of copper depend not only on solubility but also on other factors. But since so little is known about this problem, nothing can be done for the time being except to regard any copper which may be found as injurious. In the Netherlands Government Rubber Institute the permissible quantity of copper in rubber articles has been set at 0.001 per cent. Although with this percentage harmlessness is not guaranteed, it may still be expected that, with such small percentages of copper compounds, aging is not affected unfavorably. The present work is concerned chiefly with methods for determining copper.

scholarly journals Comb Construction and Brood Development on Beeswax Foundation Adulterated with Paraffin

2013 ◽  
Vol 57 (1) ◽  
pp. 75-83 ◽  
Author(s):  
Piotr Semkiw ◽  
Piotr Skubida
Keyword(s):  
Negative Impact ◽  
Domestic Market ◽  
Chemical Compositions ◽  
Brood Rearing ◽  
Brood Development ◽  
Bee Colonies ◽  
Harmful Effects

Summary In 2010 - 2011 the influence of beeswax foundation adulterated with different percentages of paraffin, on comb construction, brood rearing and bee colonies development was evaluated. Beeswax foundation adulterated with different rate of paraffin (10%, 30%, 50%) was prepared. Each year of the study into 7 experimental bee colonies set in Dadant type bee-hives, the three-frames queen insulators were inserted. Every frame in the insulators had a half of the foundation made from pure beeswax (the control - 0% paraffin) and a second half made from wax adulterated with paraffin (experimental). As a result every colony had an insulator with 3 frames with beeswax foundation with different percentages of paraffin (10 and 0%, 30 and 0%, 50 and 0%). The queens were put in the insulators what stimulated bees to prepare a place for laying eggs, thus, to construct the combs on the foundation. Paraffin used in our experiment had no negative impact on the bee colonies. Bees drew out the foundation properly, and no destruction was observed. The queens laid eggs on the systematically drawn out comb cells. Brood development was normal and its quality was suitable. The worker bees emerged after 21 days. No case of brood or emerging worker bees death was noted. Because of the different chemical compositions and purities of the paraffin available on the domestic market, it is impossible to exclude the fact that such paraffin may cause harmful effects on bee colonies.

The Restraining of Vulcanization in Rubber Manufacture

1935 ◽  
Vol 8 (2) ◽  
pp. 230-238
Author(s):  
D. F. Twiss ◽  
F. A. Jones
Keyword(s):  
Hydrogen Atom ◽  
Time Lag ◽  
Rubber Mixture ◽  
The Past ◽  
Chemical Derivatives ◽  
Other Substances ◽  
Delayed Action ◽  
Derivatives Of ◽  
Vulcanization Accelerator ◽  
Made In

Abstract Delayed-Action Accelerators During the past few years, considerable advance has been made in the ordinary method of compounding technic with respect to scorching. The advances fall essentially into two well-marked divisions, viz., the development of “delayed-action accelerators” and the addition of “vulcanization restrainers,” “inhibitors of prevulcanization,” or “antiscorch agents.” With a true delayed-action accelerator vulcanization should not occur until a certain period of time has elapsed, after which rapid vulcanization takes place. The existence of this “time lag” can be explained on the basis that the reputed accelerators are inactive, but on heating are decomposed into other substances which constitute the real accelerators. Some organic accelerators give a temperature lag, and though comparatively safe from prevulcanization in processing, they vulcanize only above a certain critical temperature. Hence, when the rubber mixture is heated, vulcanization does not take place until this temperature is attained. Such accelerators are not delayed-action accelerators in the narrower sense. In all organic accelerators the activity can be associated with a particular grouping, and in the simplest form of accelerator generally with a particular hydrogen atom. Most if not all delayed-action accelerators can be regarded as chemical derivatives of known powerful accelerators in which the place of the active hydrogen atom is occupied by a more or less easily displaceable organic grouping; the delayed-action accelerator is consequently often a compound, e. g., of the thio-ester or thio-ether (or even “thio-anhydride”) type, which itself strictly is not a vulcanization accelerator, but is capable of undergoing decomposition (e. g., “hydrolysis” or fission) with formation of one.

scholarly journals Industrial Applications of Dinoflagellate Phycotoxins Based on Their Modes of Action: A Review

Toxins ◽  
2020 ◽  
Vol 12 (12) ◽  
pp. 805
Author(s):  
Kichul Cho ◽  
Jina Heo ◽  
Jinwook Han ◽  
Hyun Dae Hong ◽  
Hancheol Jeon ◽  
...  
Keyword(s):  
Harmful Algal Blooms ◽  
Algal Blooms ◽  
Atmospheric Carbon Dioxide ◽  
Therapeutic Agents ◽  
Industrial Applications ◽  
Severe Damage ◽  
Distinctive Features ◽  
The Past ◽  
Modes Of Action ◽  
Harmful Effects

Dinoflagellates are an important group of phytoplanktons, characterized by two dissimilar flagella and distinctive features of both plants and animals. Dinoflagellate-generated harmful algal blooms (HABs) and associated damage frequently occur in coastal areas, which are concomitant with increasing eutrophication and climate change derived from anthropogenic waste and atmospheric carbon dioxide, respectively. The severe damage and harmful effects of dinoflagellate phycotoxins in the fishing industry have been recognized over the past few decades, and the management and monitoring of HABs have attracted much attention, leaving aside the industrial application of their valuable toxins. Specific modes of action of the organisms’ toxins can effectively be utilized for producing beneficial materials, such as Botox and other therapeutic agents. This review aims to explore the potential industrial applications of marine dinoflagellate phycotoxins; furthermore, this review focuses on their modes of action and summarizes the available knowledge on them.

25I-NBOMe: The legal LSD

2016 ◽  
Vol 33 (S1) ◽  
pp. S72-S73 ◽  
Author(s):  
I. Ezquiaga ◽  
M. Grifell ◽  
L. Galindo ◽  
L. Martínez ◽  
Á. Palma ◽  
...  
Keyword(s):  
Mass Spectrometry ◽  
Gas Chromatography Mass Spectrometry ◽  
Novel Psychoactive Substances ◽  
Psychoactive Substances ◽  
Energy Control ◽  
High Affinity ◽  
Other Substances ◽  
Competing Interest ◽  
Serotonin 2A ◽  
Harmful Effects

IntroductionNovel psychoactive substances (NPS) use is progressively increasing year on year. A new group of phenethylamines sold as legal stimulants and hallucinogens is being reported increasingly since 2012. Within this group, 25I-NBOMe is an outstanding substance with powerful effects and high affinity with the serotonin 2a (5HT2a) receptor. Several toxicity cases have been reported so far.ObjectivesTo describe the presence of 25I-NBOMe and its characteristics in samples delivered to Energy Control from 2009 to 2015 in Spain.MethodsAmong the samples, 21,198 analyzed from august 2009 to august 2015 and only those samples containing 25I-NBOMe were studied (n = 56). Samples were analyzed by Energy Control, a Spanish harm-reduction NGO that offers users the possibility of analyzing the substances they intend to consume. Analysis was done by Gas Chromatography–Mass Spectrometry.ResultsFrom 56 samples were 25I-NBOMe was found, 24 were bought as LSD (42.8%), 12 as 25I-NBOMe (21.4%), 4 as 25C-NBOMe (7.1%), 4 as 25I-NBOH (7.1%) and 12 as other substances (21.4%), gummy bears included. All samples were received from 2012 on, having the highest peak on 2013 (19 samples).Conclusions25I-NBOMe consumption represents an emerging issue with potential harmful effects, especially when the substance used is not the expected. Further pharmacokinetic, pharmacodynamic, clinical and epidemiological researches should be conducted to deepen knowledge about 25I-NBOMe and the management of its possible toxic effects. Physicians should be aware of NPS, their increasing use and the clinical differences between them.Disclosure of interestThe authors have not supplied their declaration of competing interest.

The Proöxygenic Role of Iron in the Oxidizability of Rubber

1934 ◽  
Vol 7 (2) ◽  
pp. 213-233 ◽  
Author(s):  
Charles Dufraisse ◽  
Roger Vieillefosse
Keyword(s):  
Current Practice ◽  
Manufacturing Processes ◽  
Iron Compounds ◽  
Simple Manner ◽  
Rubber Mixture ◽  
The Past ◽  
Harmful Effects

Abstract The influence of iron on the oxidizability of rubber, though not as a matter of fact neglected in the past, has perhaps not received sufficient attention. However, the various ways in which this metal and its derivatives have caused contamination are certainly too obvious to imagine that they have passed unobserved. As is known, traces of iron can be detected in latex at the time it is tapped, and regardless of the method of treatment which it undergoes later, the rubber has an opportunity at every step in its preparation to become further contaminated with iron. Milling, calendering, and molding are carried out with iron equipment, and the ingredients used in rubber compounding may contain more or lees iron, at least as impurities, even when they are not primarily iron compounds, as is the case of certain pigments. In short, manufacturing processes, contamination by iron from ingredients, adventious causes such as iron containers for latex, dust and various other causes which need not be enumerated, all contribute to the presence of iron in rubber. Certainly then iron cannot be a very dangerous element under ordinary conditions, for otherwise its harmful effects would have been recognized long ago, and would have led to the avoidance of iron in practice, as has happened in the case of copper. Nevertheless experiments of the authors to determine why vulcanization increases the oxidizability of rubber have led to the suspicion that iron may be harmful, and a desire to ascertain the role it plays in deterioration prompted the authors to carry out the experiments which are described in the present paper. The object of the work was thus limited, and it aimed not to settle the problem of the influence of iron on rubber, but rather to investigate in a simple manner in what way iron gets into a rubber mixture, in what form it exists, and what are its harmful effects. Incidental to this, some of the observations may perhaps be of some value in current practice.

Characterization of carbides in M50NiL

1991 ◽  
Vol 49 ◽  
pp. 606-607
Author(s):  
L. S. Lin ◽  
K. P. Gumz ◽  
A. V. Karg ◽  
C. C. Law
Keyword(s):  
Temperature Effects ◽  
Base Composition ◽  
Lattice Parameter ◽  
Control Surface ◽  
Carbide Formation ◽  
Particle Sizes ◽  
Low Carbon ◽  
Fee Structure ◽  
Heat Treated

Carbon and temperature effects on carbide formation in the carburized zone of M50NiL are of great importance because they can be used to control surface properties of bearings. A series of homogeneous alloys (with M50NiL as base composition) containing various levels of carbon in the range of 0.15% to 1.5% (in wt.%) and heat treated at temperatures between 650°C to 1100°C were selected for characterizations. Eleven samples were chosen for carbide characterization and chemical analysis and their identifications are listed in Table 1.Five different carbides consisting of M6C, M2C, M7C3 and M23C6 were found in all eleven samples examined as shown in Table 1. M6C carbides (with least carbon) were found to be the major carbide in low carbon alloys (<0.3% C) and their amounts decreased as the carbon content increased. In sample C (0.3% C), most particles (95%) encountered were M6C carbide with a particle sizes range between 0.05 to 0.25 um. The M6C carbide are enriched in both Mo and Fe and have a fee structure with lattice parameter a=1.105 nm (Figure 1).

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