Prevulcanization Inhibitor the Chemistry of Scorch Delay

1970 ◽  
Vol 43 (5) ◽  
pp. 1188-1193 ◽  
Author(s):  
R. I. Leib ◽  
A. B. Sullivan ◽  
C. D. Trivette
Keyword(s):  
Delay Period ◽  
Crosslinking Process ◽  
Time Period ◽  
Rubber Compounds ◽  
Speed Up ◽  
Autocatalytic Process ◽  
Vulcanization Process

Abstract Sulfenamide accelerators serve to perform two functions. They provide the necessary time period required to mix, process and shape rubber compounds. This portion of the overall vulcanization process is usually referred to as scorch delay. In addition, sulfenamides function as accelerators, in that once the crosslinking process has begun, they speed up this reaction. The delay period occurs because the sulfenamide must be converted to polythiobenzothiazoles, the precursors to crosslinking, before crosslinking can take place. The overall reaction of sulfenamide with sulfur is an autocatalytic process with MBT the autocatalyst. The role of PVI in this scheme is to remove MBT from this autocatalytic sequence of reactions, thus delaying those reactions which preceed crosslink formation.

Activators in Accelerated Sulfur Vulcanization

2004 ◽  
Vol 77 (3) ◽  
pp. 512-541 ◽  
Author(s):  
Geert Heideman ◽  
Rabin N. Datta ◽  
Jacques W. M. Noordermeer ◽  
Ben van Baarle
Keyword(s):  
Reaction Mechanisms ◽  
Model Compound ◽  
Background Information ◽  
Zinc Compounds ◽  
Chemical Mechanisms ◽  
Sulfur Vulcanization ◽  
Multifunctional Additives ◽  
Vulcanization Process

Abstract This review provides relevant background information about the vulcanization process, as well as the chemistry of thiuram- and sulfenamide-accelerated sulfur vulcanization with emphasis on the role of activators, to lay a base for further research. It commences with an introduction of sulfur vulcanization and a summary of the reaction mechanisms as described in literature, followed by the role of activators, particularly ZnO. The various possibilities to reduce ZnO levels in rubber compounding, that have been proposed in literature, are reviewed. A totally different approach to reduce ZnO is described in the paragraphs about the various possible roles of multifunctional additives (MFA) in rubber vulcanization. Another paragraph is dedicated to the role of amines in rubber vulcanization, in order to provide some insight in the underlying chemical mechanisms of MFA systems. Furthermore, an overview of Model Compound Vulcanization (MCV) with respect to different models and activator/accelerator systems is given. In the last part of this review, the various functions of ZnO in rubber are summarized. It clearly reveals that the role of ZnO and zinc compounds is very complex and still deserves further clarification.

Possible Role of High-Dose Barbiturates and Early Administration of Parenteral Ketogenic Diet for Reducing Development of Chronic Epilepsy in Febrile Infection-Related Epilepsy Syndrome: A Case Report

2020 ◽  
Author(s):  
Shimpei Baba ◽  
Tohru Okanishi ◽  
Koichi Ohsugi ◽  
Rika Suzumura ◽  
Keiko Niimi ◽  
...  
Keyword(s):  
Continuous Infusion ◽  
Ketogenic Diet ◽  
Epilepsy Syndrome ◽  
High Dose ◽  
Early Administration ◽  
Chronic Epilepsy ◽  
Time Period ◽  
Irreversible Brain Damage ◽  
Electroencephalogram Eeg

AbstractWe describe the efficacy of high-dose barbiturates and early administration of a parenteral ketogenic diet (KD) as initial treatments for acute status epilepticus (SE) in an 8-year-old girl with febrile infection-related epilepsy syndrome (FIRES). The patient was admitted to our hospital with refractory focal SE. Abundant epileptic discharges over the left frontal region were observed on electroencephalogram (EEG). Treatment with continuous infusion of thiamylal for 4 hours, increased incrementally to 40 mg/kg/h, successfully ended the clinical SE, and induced a burst-suppression coma. The infusion rate was then gradually decreased to 4 mg/kg/h over the next 12 hours. Parenteral KD was administered from days 6 to 21 of illness. Continuous infusion of thiamylal was switched to midazolam on day 10 without causing seizures or EEG exacerbations. The patient has remained seizure free in the 15 months since hospital discharge. The effectiveness of KD for the treatment of FIRES has attracted attention amongst clinicians, but KD treatment may need to last for 2 to 4 days before it can stop SE, a time period that could cause irreversible brain damage. Considering the severity of SE in our patient and the dose of barbiturates needed to treat it, we consider this case to have had a good clinical outcome. The results suggest that rapid termination of seizure using high-dose barbiturates in conjunction with early administration of parenteral KD could reduce the development of chronic epilepsy in patients with FIRES.

scholarly journals Identification and developmental regulation of a neuron-specific subunit of cytoplasmic dynein.

1996 ◽  
Vol 7 (2) ◽  
pp. 331-343 ◽  
Author(s):  
K K Pfister ◽  
M W Salata ◽  
J F Dillman ◽  
E Torre ◽  
R J Lye
Keyword(s):  
Axonal Transport ◽  
Developmental Regulation ◽  
Cytoplasmic Dynein ◽  
Retrograde Axonal Transport ◽  
Protein Isoforms ◽  
Cultured Neurons ◽  
Developmentally Regulated ◽  
Time Period ◽  
Intermediate Chains

Cytoplasmic dynein is the microtubule minus-end-directed motor for the retrograde axonal transport of membranous organelles. Because of its similarity to the intermediate chains of flagellar dynein, the 74-kDa intermediate chain (IC74) subunit of dynein is thought to be involved in binding dynein to its membranous organelle cargo. Previously, we identified six isoforms of the IC74 cytoplasmic dynein subunit in the brain. We further demonstrated that cultured glia and neurons expressed different dynein IC74 isoforms and phospho-isoforms. Two isoforms were observed when dynein from glia was analyzed. When dynein from cultured neurons was analyzed, six IC74 isoforms were observed, although the relative amounts of the dynein isoforms from cultured neurons differed from those found in dynein from brain. To better understand the role of the neuronal IC74 isoforms and identify neuron-specific IC74 dynein subunits, the expression of the IC74 protein isoforms and mRNAs of various tissues were compared. As a result of this comparison, the identity of each of the isoform spots observed on two-dimensional gels was correlated with the products of each of the IC74 mRNAs. We also found that between the fifteenth day of gestation (E15) and the fifth day after birth (P5), the relative expression of the IC74 protein isoforms changes, demonstrating that the expression of IC74 isoforms is developmentally regulated in brain. During this time period, there is relatively little change in the abundance of the various IC74 mRNAs. The E15 to P5 time period is one of rapid process extension and initial pattern formation in the rat brain. This result indicates that the changes in neuronal IC74 isoforms coincide with neuronal differentiation, in particular the extension of processes. This suggests a role for the neuronal IC74 isoforms in the establishment or regulation of retrograde axonal transport.

Exodus

2021 ◽  
Vol 2 (11) ◽  
pp. 37-51
Author(s):  
Geoffrey Hart ◽  
Keyword(s):  
Short Story ◽  
Jewish People ◽  
Deep Space ◽  
Traditional Foods ◽  
Religious Ceremony ◽  
Time Period ◽  
Archeological Evidence ◽  
Historical Basis ◽  
The Right

What makes a "religious" holiday? Does the combination of ritual, culture, and family custom all merge together to create "religion?" Does it even matter if the historical basis for religious stories are false? In this work of philosophical short story fiction, the spaceship computer AI wakes up a family in deep space hibernation to give them time to prepare for, and celebrate, Passover. There are many situations unique to being in space that must be overcome; determining the right time period when taking into consideration time dilation, not to mention missing ingredients for traditional foods. Also, they are short two people of the requisite ten and ask the computer AI to "convert" and serve the role of two additional Jewish people. Awkwardly, the computer reminds them that some of their traditional stories are not supported by archeological evidence. This all begs important questions about the complicated weaving of history, faith, culture, and family custom in religious ceremony.

Radical Mechanisms in Saturated and Olefinic Systems. II. Disubstitutive Carbon-Carbon Cross-Linking by Tertiary Alkoxy Radicals in Isoprenic Olefins and Rubber

1951 ◽  
Vol 24 (4) ◽  
pp. 777-786
Author(s):  
E. H. Farmer ◽  
C. G. Moore
Keyword(s):  
Natural Rubber ◽  
Cross Linking ◽  
Chain Molecules ◽  
Alkoxy Radicals ◽  
Full Extent ◽  
Carbon Chains ◽  
Butyl Peroxide ◽  
High Degree ◽  
Vulcanization Process

Abstract The high degree of dehydrogenation effected by tert.-butoxy radicals at the α-methylenic groups of olefins enables these radicals to be used for the carbon-to-carbon cross-linking of unsaturated carbon chains, and especially of the polyisoprenic chains of natural rubber. Such cross-linking amounts to a vulcanization process in which the connecting links between chain molecules are just C—C bonds, which may be expected to have appropriate attributes. An examination has first been made of the cross-linking produced by tert.- butoxy radicals (from di-tert.-butyl peroxide) at 140° between the short iso-prenic chains in 1-methylcyclohexene, 4-methylhept-3-ene, 2,6-dimethylocta-2, 6-diene, and digeranyl. Cross-linking proceeds efficiently in each case, and the points of union in these isoprene units which become directly joined are not confined to original α-methylenic carbon atoms. Where the reagent radicals are in considerable deficit, e.g., one per two or three of the isoprene units present, those olefin molecules which are attacked become linked together mostly by single unions to form aggregates containing two, three or four molecules; but in the tetraisoprenic olefins the extent to which more than one union is formed between some of the directly linked molecules becomes appreciable. In natural rubber, cross-linking occurs smoothly and to nearly the full extent corresponding to the (in practice restricted) proportion of peroxidic reagent employed. Good vulcanizates can be so obtained in which the tensile stength is found to increase towards a maximum and then to decline rapidly as the degree of cross-linking steadily increases. Thus to obtain vulcanizates of the optimum physical characteristics, the degree of cross-linking must be suitably chosen. The role of the peroxidic reagent is almost entirely non-additive and non-degradative.

scholarly journals The Model of Sociological Education in the USSR (the Late 1950s — Early 1980s)

2021 ◽  
pp. 112-117
Author(s):  
Sergei V. Kozin ◽  
Zhanna B. Litvinova
Keyword(s):  
Sociological Research ◽  
Scientific Publications ◽  
Mutual Exchange ◽  
Research Areas ◽  
Time Period ◽  
The Given ◽  
Soviet Sociology

The article provides an analysis of foreign and Soviet scientific publications devoted to the problem of sociological education, the “revival” of Soviet sociology, as well as to the role and place of sociology among the sciences, in society and education. The given study covers the time period of the late 1950s — early 1980s and briefly describes the education of the population of the USSR at that time. Looking through the works on Soviet sociology, the authors show that sociology was introduced not only into the research areas of specific universities and laboratories, but also into many other branches and spheres of activity, as well as into the authorities’ activity. The authors of the article purposefully focus on the role of consolidation and mutual exchange of sociological research from various sociological services.

scholarly journals Analytical and diagnostic performances of a high-throughput immunoassay for SARS-CoV-2 IgM and IgG

2020 ◽  
Author(s):  
Andrea Padoan ◽  
Chiara Cosma ◽  
Paolo Zaupa ◽  
Mario Plebani
Keyword(s):  
Sensitivity And Specificity ◽  
Symptom Onset ◽  
Severe Disease ◽  
Onset Time ◽  
Time Frame ◽  
Serum Samples ◽  
Time Period ◽  
Analytical Imprecision ◽  
Range Of Values

BackgroundAbstractReliable SARS-CoV-2 serological assays are required for diagnosing infections, for the serosurveillance of past exposures and for assessing the response to future vaccines. In this study, the analytical and clinical performances of a chemiluminescent immunoassays for SARS-CoV-2 IgM and IgG detection (Mindray CL-1200i), targeting Nucleocapsid (N) and receptor binding domain (RBD) portion of the Spike protein, were evaluated.MethodsPrecision and linearity were evaluated using standardized procedures. A total of 157 leftover serum samples from 81 hospitalized confirmed COVID-19 patients (38 with moderate and 43 with severe disease) and 76 SARS-CoV-2 negative subjects (44 healthcare workers, 20 individuals with rheumatic disorders, 12 pregnant women) were included in the study. In an additional series of 44 SARS-CoV-2 positive, IgM and IgG time kinetics were also evaluated in a time-period of 38 days.ResultsPrecision was below or equal to 4% for both IgM and IgG, in all the studied levels, whilst a slightly significant deviation from linearity was observed for both assays in the range of values covering the manufacturer’s cut-off. Considering a time frame ≥ 12 days post symptom onset, sensitivity and specificity for IgM were 92.3% (95%CI:79.1%-98.4%) and 92.1% (95%CI:83.6%-97.0%). In the same time frame, sensitivity and specificity for IgG were 100% (95%CI:91.0%-100%) and 93.4% (95%CI:85.3%-97.8%). The assays agreement was 73.9% (Cohen’s kappa of 0.373). Time kinetics showed a substantial overlapping of IgM and IgG response, the latter values being elevated up to 38 days from symptoms onset.ConclusionsAnalytical imprecision is satisfactory as well as the linearity, particularly when taking into account the fact that both assays are claimed to be qualitative. Diagnostic sensitivity of IgG was excellent, especially considering specimens collected ≥12 days post symptom onset. Time kinetics suggest that IgM and IgG are detectable early in the course of infection, but the role of SARS-CoV-2 antibodies in clinical practice still requires further evaluations.

scholarly journals A Diary Study on When and With Whom Recovery Experiences Modulate Daily Stress and Worry During a COVID-19 Lockdown

2021 ◽  
Vol 12 ◽  
Author(s):  
Julie Ménard ◽  
Annie Foucreault ◽  
Hugues Leduc ◽  
Sophie Meunier ◽  
Sarah-Geneviève Trépanier
Keyword(s):  
Mental Health ◽  
Negative Mood ◽  
Future Research ◽  
Daily Stress ◽  
Multiple Risk Factors ◽  
Time Period ◽  
Lag Effect ◽  
Recovery Experiences ◽  
Measured Time

In April 2020, almost six out of 10 people around the world were in lockdown due to the COVID-19 pandemic. Being locked down usually has a deleterious effect on the confined individual's mental health. In this exceptionally challenging context, finding ways to minimize negative mood about the pandemic is essential. Pandemic-related negative states (“negative mood”) and recovery experiences were investigated in a sample of 264 individuals who completed daily surveys four times per day over 7 consecutive days. MSEMs analyses revealed that negative mood persisted from moment-to-moment through the day, thus showing a response lag effect. Further analyses revealed that when someone experienced pandemic-related psychological detachment, relaxation, mastery, control, pleasure, or relatedness at specific periods of the day, mood had improved at the next measured time period, suggesting a protective effect. However, the pattern displayed by singles with dependents suggests that some recovery experiences at specific periods during the day seem to have a backfiring effect and worsen subsequent mood. These findings bring new insight into the role of recovery experiences during lockdowns and suggest that many could benefit from such experiences throughout the day when self-isolating. However, for individuals with multiple risk factors such as being single with dependents, some recovery experiences, at specific periods during the day, might not bring the desired outcome and future research is needed to examine if guilt or domestic burden may explain this finding. Results contribute to our understanding of how to take care of one's mental health during the current pandemic, and concrete recommendations adapted to individual contexts are provided.

scholarly journals Design and verification of additional filtration for the application of ecological transmission and hydraulic fluids in tractorc

2013 ◽  
Vol 61 (5) ◽  
pp. 1305-1311 ◽  
Author(s):  
Pavel Máchal ◽  
Radoslav Majdan ◽  
Zdenko Tkáč ◽  
Bohuslav Stančík ◽  
Rudolf Abrahám ◽  
...  
Keyword(s):  
Chemical Elements ◽  
Main Role ◽  
Additive Concentration ◽  
Test Operation ◽  
Time Period ◽  
Medium Level ◽  
Agricultural Tractors ◽  
High Level ◽  
And Function

This contribution presents the design and function verification of additional filtration. It is intended for the common transmission and hydraulic oil filling of tractors. The main role of this filtration concept is to ensure a high level of oil cleanness as a condition for the application of ecologic fluids in tractors. The next one is to decrease the wear of lubricated tractor components, the degradation of oil and eventually to extend the interval of oil change. The designed additional filtering is characterized by ease installation through the use of quick couplings and hoses to the external hydraulic circuit. Therefore, the filtration is suitable for various tractor types. Filter element has been designed with the filter ability 1micron and the ability to separate to 0.5 dm3 of water from oil. Function of additional filtration was verified during the 150 engine hours of tractor operation. During this time period the oil contamination was evaluated on the basis of chemical elements content such as Fe, Cu, Si, Al, Ni, Mo and Cr. The additive concentration was evaluated on the basis of chemical elements content such as Ca, P and Zn. During the test operation of tractor the concentration decrease of chemical elements reached the values 25.53 % (Fe), 23.53 % (Si), 25 % (Al) and 5.5 % (Cu). The decrease of additive concentration reached only medium level (6.6 %). Therefore, the designed additional filtration doesn’t remove additives from oil. Based on the evaluation of the content of chemical elements (that representing contamination and additives), we can say that the designed filtering method is suitable for use in agricultural tractors.

scholarly journals ROLE OF TRAM TRANSIT IN FORMATION OF MAGNITOGORSK TRANSPORTATION SYSTEM (1930–1955)

2020 ◽  
Vol 17 (5) ◽  
pp. 316-325
Author(s):  
M. N. Potemkina ◽  
M. V. Gryaznov ◽  
T. G. Pashkovskaya ◽  
E. A. Timofeev
Keyword(s):  
Soviet Union ◽  
Transport System ◽  
Urban Transport ◽  
Political Life ◽  
Information Support ◽  
Transport Systems ◽  
Electric Transport ◽  
Route Network ◽  
Time Period

The article provides information about the state of Magnitogorsk electric transport during its formation. This is one of the steps to preserving the history of emergence and development of tram traffic, an attempt to outline its fundamental role in formation of the transport system, as well as in socio-economic and political life of Magnitogorsk, one of the first so called social cities of the Soviet Union. The article is structured into sections relating to expansion of the tram route network, state and development of tram fleet. The considered time period captures the years of the Great Patriotic War and is limited to the beginning of the «thaw» in the domestic political life of the Soviet state. Through systematization of documentary evidence, the fundamental role of tram traffic in formation of the transport system of Magnitogorsk for the studied time period is determined. This should contribute to development of information support for research on the historical patterns of formation of urban transport systems in the period of industrialization.This issue offers the first part of the article.

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