Aging of Tire Parts during Service. I. Types of Aging in Heavy-Duty Tires

1990 ◽  
Vol 63 (5) ◽  
pp. 683-697 ◽  
Author(s):  
Asahiro Ahagon ◽  
M. Kida ◽  
H. Kaidou
Keyword(s):  
High Temperatures ◽  
Laboratory Evaluation ◽  
Thickness Variation ◽  
Type I ◽  
Heavy Duty ◽  
Oxidative Aging ◽  
The Third ◽  
Air Supply ◽  
Oxidative Condition ◽  
Reference Relation

Abstract Three types of aging were found to exist. The factors determining the types were the temperature and the air-supply conditions irrespective of where the rubber was aged, in the tires or in the laboratory. This means that the aging characteristics of a tire part in the field can be properly predicted if these factors in a tire are taken into account in the laboratory evaluation. In the first type, Type I, the aging yields increased M100 and reduced λb closely following the reference relation, Equation (3), which holds for the rubbers crosslinked with increasing the amount of curatives. This type of aging was found at temperatures below about 80°C, under either oxidative or anaerobic conditions. The extents of the changes in λb and M100 were large under the former conditions and small under the latter. As for the aging in the heavy-duty tires, the sidewall and the belt showed this type, with the changes to considerable extents suggesting an oxidative aging. The oxidative condition for the sidewall is apparent. Although air supply to the belt seems difficult because of the interior position and the massiveness of the tires, the cords of air wicking type occupy a substantial section of the part shortening the permeation path of the inflating air to create an oxidative condition. This type of aging is governed substantially by crosslinking, so that aging yields the same effect on the λb vs.M100 relation as the one obtained in crosslinking with increasing curatives. In the second type, Type II, M100 was either changed little or even reduced, while λb was reduced. This type was observed in an anaerobic aging at temperatures higher than about 90°C. The extents of the changes in this type appeared relatively small. This type of aging in the heavy-duty tires was observed mainly in the belt-edge filler and sporadically in the belt. The belt-edge fillers are placed at the edges above the second and below the third belt layers with the thickness considerably larger than that of the belt rubber between the cords. This makes the air supply condition in the part virtually anaerobic. Furthermore, being in the midsection of the thick crown region and under a severe flexural condition, the part should operate at considerably high temperatures. The sporadic appearance of this type in the belt may be due to the thickness variation of the rubber layers including the underlying parts, together with the severe service conditions causing extensive temperature rise in the particular service. The characteristics of this type are speculated to come from extensive main-chain modifications like cyclic sulfide formations. In the third type, Type III, M100 was increased, and λb was reduced but to an extent larger than expected from the M100 value on the basis of the reference relation. This type was obtained in the oxidative aging at temperatures above about 90°C. This type of aging was not found in the tire parts of the present study. The causes of this type are considered to be from appreciable amounts of chain scission in addition to crosslinking, due to oxidation at high temperatures.

Selective Oxidation and the Third-Element Effect on the Oxidation of Mg-Y Alloys at High Temperatures

2009 ◽  
Vol 40 (9) ◽  
pp. 2184-2189 ◽  
Author(s):  
J.F. Fan ◽  
G.C. Yang ◽  
Y.H. Zhou ◽  
Y.H. Wei ◽  
B.S. Xu
Keyword(s):  
Selective Oxidation ◽  
High Temperatures ◽  
The Third

Maturation process and characterization of a novel thermostable and halotolerant subtilisin-like protease with high collagenolytic but low gelatinolytic activity

2021 ◽  
Author(s):  
Kui Zhang ◽  
Qianqian Huang ◽  
Yu Li ◽  
Lanhua Liu ◽  
Xiao-Feng Tang ◽  
...  
Keyword(s):  
High Temperatures ◽  
Type I Collagen ◽  
Elevated Temperatures ◽  
Catalytic Domain ◽  
Ion Pairs ◽  
Gelatinolytic Activity ◽  
Type I ◽  
Fish Scale ◽  
Collagenolytic Proteases ◽  
Collagenolytic Protease

Enzymatic degradation of collagen is of great industrial and environmental significance; however, little is known about thermophile-derived collagenolytic proteases. Here, we report a novel collagenolytic protease (TSS) from thermophilic Brevibacillus sp. WF146. The TSS precursor comprises a signal peptide, an N-terminal propeptide, a subtilisin-like catalytic domain, a β-jelly roll (βJR) domain, and a prepeptidase C-terminal (PPC) domain. The maturation of TSS involves a stepwise autoprocessing of the N-terminal propeptide and the PPC domain, and the βJR rather than the PPC domain is necessary for correct folding of the enzyme. Purified mature TSS displayed optimal activity at 70°C and pH 9.0, a half-life of 1.5 h at 75°C, and an increased thermostability with rising salinity up to 4 M. TSS possesses an increased number of surface acidic residues and ion pairs, as well as four Ca 2+ -binding sites, which contribute to its high thermostability and halotolerance. At high temperatures, TSS exhibited high activity toward insoluble type I collagen and azocoll, but showed a low gelatinolytic activity, with a strong preference for Arg and Gly at the P1 and P1’ positions, respectively. Both the βJR and PPC domains could bind but not swell collagen, and thus facilitate TSS-mediated collagenolysis via improving the accessibility of the enzyme to the substrate. Additionally, TSS has the ability to efficiently degrade fish scale collagen at high temperatures. IMPORTANCE Proteolytic degradation of collagen at high temperatures has the advantages of increasing degradation efficiency and minimizing the risk of microbial contamination. Reports on thermostable collagenolytic proteases are limited, and their maturation and catalytic mechanisms remain to be elucidated. Our results demonstrate that the thermophile-derived TSS matures in an autocatalytic manner, and represents one of the most thermostable collagenolytic proteases reported so far. At elevated temperatures, TSS prefers hydrolyzing insoluble heat-denatured collagen rather than gelatin, providing new insight into the mechanism of collagen degradation by thermostable collagenolytic proteases. Moreover, TSS has the potential to be used in recycling collagen-rich wastes such as fish scales.

ELECTROLYTIC EXCHANGE FEATURES DURING MYOCARDIAL INFARCTION WITH RECURRENT EPISODES OF ISCHEMIA IN MEN UNDER 60 YEARS OLD

2021 ◽  
pp. 120-126
Author(s):  
Golikov A.V. ◽  
Epifanov S.Yu. ◽  
Reiza V.A.
Keyword(s):  
Myocardial Infarction ◽  
Blood Serum ◽  
Absolute Risk ◽  
Risk Groups ◽  
Unfavorable Outcome ◽  
Study Group ◽  
Type I ◽  
Sodium Potassium ◽  
The Third ◽  
Recurrent Myocardial Infarction

Relevance. Recurrent myocardial infarction and early postinfarction angina negatively effects on the prognosis of myocardial infarction. Aim. To evaluate myocardial infarction sodium, potassium, chlorides, calcium metabolism, features in men under 60 years old with recurrent myocardial infarction and early postinfarction angina to improve prevention and outcomes. Material and methods. The study included men aged 19-60 years old with type I myocardial infarction. Patients are divided into two age-comparable groups: I - the study group, with recurrent myocardial infarction - 110 patients; II - control, without it - 555 patients. A comparative analysis of blood serum electrolyte levels, their dynamics from the first hours to the end of the third week of myocardial infarction in the selected groups were performed. Their impact on the risk of recurrent ischemia and unfavorable outcome was assessed. Results. In the study group, in the first hours of the disease, the levels of chloride were higher (103.7±5.5 and 101.7±4.7 (mmol/l); p=0.002), and total calcium at the end of the third week of myocardial infarction (2.3±0.2 mmol/l) - lower than in the control (2.46±0.16; p=0.001). With an unfavorable outcome in the study group, the sodium level was lower in the first hours of the disease (138.7±4.9 and 142.7±6.6 (mmol/l); p=0.049). Moreover, the risk of its development was associated with sodium levels ≥148.0 mmol/l (absolute risk: 100.0%; relative - 13.8; p<0.0001) and potassium levels ≥5.3 mmol/l (absolute: 71,4%; relative - 12.4; p<0.0001). The risk of developing recurrent episodes of ischemia in the examined increased at chloride levels ≥104.7 mmol/l (absolute: 28.4%; relative: 3.1; p=0.0001) and sodium ≥139.0 mmol/l (absolute: 19.5%; relative: 1.7; p=0.03) in the first hours of myocardial infarction and calcium (<2.4 mmol/l) at the end of the third week of the disease (absolute: 31.0%; relative: 4.9; p=0.003). Conclusions. The listed combinations of levels of basic electrolytes in blood serum are markers of recurrence of ischemia in myocardial infarction and poor outcome. They should be used to identify risk groups with the necessary preventive measures and for predictive modeling.

Aromatase Inhibitors in the Treatment and Prevention of Breast Cancer

2001 ◽  
Vol 19 (3) ◽  
pp. 881-894 ◽  
Author(s):  
Paul E. Goss ◽  
Kathrin Strasser
Keyword(s):  
Breast Cancer ◽  
Aromatase Inhibitors ◽  
Clinical Status ◽  
Phase Iii ◽  
Type I ◽  
Third Generation ◽  
Line Treatment ◽  
Second Line ◽  
First Line ◽  
The Third

PURPOSE: The purpose of this article is to provide an overview of the current clinical status and possible future applications of aromatase inhibitors in breast cancer. METHODS: A review of the literature on the third-generation aromatase inhibitors was conducted. Some data that have been presented but not published are included. In addition, the designs of ongoing trials with aromatase inhibitors are outlined and the implications of possible results discussed. RESULTS: All of the third-generation oral aromatase inhibitors—letrozole, anastrozole, and vorozole (nonsteroidal, type II) and exemestane (steroidal, type I)—have now been tested in phase III trials as second-line treatment of postmenopausal hormone-dependent breast cancer. They have shown clear superiority compared with the conventional therapies and are therefore considered established second-line hormonal agents. Currently, they are being tested as first-line therapy in the metastatic, adjuvant, and neoadjuvant settings. Preliminary results suggest that the inhibitors might displace tamoxifen as first-line treatment, but further studies are needed to determine this. CONCLUSION: The role of aromatase inhibitors in premenopausal breast cancer and in combination with chemotherapy and other anticancer treatments are areas of future exploration. The ongoing adjuvant trials will provide important data on the long-term safety of aromatase inhibitors, which will help to determine their suitability for use as chemopreventives in healthy women at risk of developing breast cancer.

Cromwell Mortimer, F. R. S. ( c . 1698-1752) and the invention of the metalline thermometer for measuring high temperatures

1969 ◽  
Vol 24 (1) ◽  
pp. 113-135 ◽  
Keyword(s):  
Eighteenth Century ◽  
Seventeenth Century ◽  
High Temperatures ◽  
Boiling Point ◽  
Early Years ◽  
Fourth Degree ◽  
The Third ◽  
Upper Limit

Although the liquid-in-glass thermometer came into use either in the last decade of the sixteenth or during the early years of the seventeenth century (1), it was not until the eighteenth century that reproducible scales of temperature were established, arising from the work of Fahrenheit (2), Reaumur (3) and Celsius (4). So far as eighteenth-century chemists were concerned, the upper limit of temperature to which the liquid-in-glass thermometer could be used was set by the boiling point of mercury, at that time assumed to be 600 °F (5). In the latter half of the seventeenth century any temperatures attained in chemical operations could be indicated only by reference to a scale comprising some seven ‘degrees of heat’. In the middle to upper ranges, for example, to quote from Glaser’s The Compleat Chymist , the third ‘degree’ was that of hot ashes; the fourth ‘degree’ was that of hot sand, and the fifth that of hot iron filings; the sixth ‘degree’ was attained in the closed reverberatory charcoal fire, and the seventh and highest ‘degree’ was the ‘Flaming-Fire or Fire of Fusion’, made with wood or charcoal (6).

Elasto-Viscoplastic Dispersive Waves in Silicon Wafers

2007 ◽  
Author(s):  
Li Liu ◽  
C. Steve Suh
Keyword(s):  
Stress Wave ◽  
High Temperatures ◽  
Nonlinear Function ◽  
Low Frequency ◽  
Propagation Model ◽  
Constitutive Law ◽  
Stress Wave Propagation ◽  
Thickness Variation ◽  
Low Frequencies ◽  
Induced Stress

This paper provides the required knowledge base for establishing Laser Induced Stress Wave Thermometry (LISWT) as a viable alternative to current infrared technologies for temperature measurement up to 1000°C with ±1°C resolution. A stress wave propagation model having a complex, temperature-dependent elasto-viscoplastic constitutive law is developed. Investigated results show that wave group velocity is a nonlinear function of temperature. Nonlinearity becomes more prominent at high temperatures and low frequencies. As such, for LISWT to achieve better thermal resolution at high temperatures, low frequency components of the induced stress wave should be exploited. The results also show that the influence of temperature on attenuation is relatively small. It is not recommended to use attenuation for resolving temperature variation as small as several degrees Celsius. In addition to temperature, geometry also is found to have an impact on wave dispersion and attenuation. The influence of thickness on wave velocity is significant, thus suggesting that for LISWT to achieve high temperature resolution, wafer thickness must be accurately calibrated in order to eliminate all possible errors introduced by thickness variation.

Why Schools Should Care About Intellectual Styles

2012 ◽  
Vol 11 (3) ◽  
pp. 256-270 ◽  
Author(s):  
Li-fang Zhang
Keyword(s):  
Research Evidence ◽  
School Context ◽  
Educational Institutions ◽  
Type I ◽  
Type Ii ◽  
Learning And Development ◽  
The Third ◽  
Intellectual Styles ◽  
Processing Information ◽  
Research Findings

Traditionally, many educators and psychologists believed that successes and failures within the school context are attributable mainly to individual differences in such classic variables as ability, personality, and learning motivation. This article presents research evidence demonstrating that intellectual styles, that is, people’s preferred ways of processing information and dealing with tasks, also play critical roles in students’ learning and development and in teachers’ practices. It further demonstrates that some styles are more valued than are others and that styles are malleable.The article is divided into four parts. The first part briefly introduces the background of the research to be presented. The second reviews the key literature, supporting the position that intellectual styles are value laden, with creativity-generating styles (also known as Type I styles) being more adaptive than are norm-favoring styles (also known as Type II styles). The third part highlights some research findings indicating that styles can be modified. The final and fourth part of the article discusses the implications of the research evidence for various parties of educational institutions at all levels—generally referred to as “schools” in this article.

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