Thermochemical characterization of Zr/Fe2O3 pyrotechnic mixture under natural aging conditions

2019 ◽  
Vol 126 (10) ◽  
pp. 105113 ◽  
Author(s):  
Byung Heon Han ◽  
Yoocheon Kim ◽  
Seung-gyo Jang ◽  
Jeayong Yoo ◽  
Jack J. Yoh
Keyword(s):  
Natural Aging ◽  
Pyrotechnic Mixture ◽  
Aging Conditions

Accelerated aging and characterization of HDPE pin type insulators (15 kV)

2021 ◽  
pp. 096739112110476
Author(s):  
Cynthia DC Erbetta ◽  
Maria Elisa SR Silva ◽  
Roberto FS Freitas ◽  
Ricardo G Sousa
Keyword(s):  
Differential Scanning Calorimetry ◽  
Fourier Transform ◽  
High Density Polyethylene ◽  
Accelerated Aging ◽  
Natural Aging ◽  
Accelerated Weathering ◽  
Electrical System ◽  
Scanning Calorimetry ◽  
Aging Conditions

The study of the behavior of polymeric material used for insulators in the electrical system is extremely important in order to evaluate their lifetime as well as their performance when exposed to different environmental conditions. In the present work, the behavior of high-density polyethylene (HDPE) pin type insulators (15 kV), under accelerated aging conditions, was studied. Samples were exposed to aging, for 200 h, 1000 h, and 2000 h, in accelerated weathering chambers, according to two different methods. In Method 1, the parameters were established based on natural aging in location conditions, and in Method 2, ASTM G155 standard parameters were used. All samples were characterized by rheometry, Fourier-transform infrared spectroscopy (FTIR), and differential scanning calorimetry (DSC). The accelerated aging conditions, used in Methods 1 and 2, affected the aging of HDPE pin type insulators samples differently, the changes being more intense in Method 1.

scholarly journals Longitudinal Characterization of the Gut Bacterial and Fungal Communities in Yaks

2021 ◽  
Vol 7 (7) ◽  
pp. 559
Author(s):  
Yaping Wang ◽  
Yuhang Fu ◽  
Yuanyuan He ◽  
Muhammad Fakhar-e-Alam Kulyar ◽  
Mudassar Iqbal ◽  
...  
Keyword(s):  
Natural Aging ◽  
Fungal Communities ◽  
Significant Shift ◽  
Mature Adult ◽  
Bacterial Phyla ◽  
Development Stages ◽  
Composition And Structure ◽  
Intestinal Functions ◽  
Development Phases

Development phases are important in maturing immune systems, intestinal functions, and metabolism for the construction, structure, and diversity of microbiome in the intestine during the entire life. Characterizing the gut microbiota colonization and succession based on age-dependent effects might be crucial if a microbiota-based therapeutic or disease prevention strategy is adopted. The purpose of this study was to reveal the dynamic distribution of intestinal bacterial and fungal communities across all development stages in yaks. Dynamic changes (a substantial difference) in the structure and composition ratio of the microbial community were observed in yaks that matched the natural aging process from juvenile to natural aging. This study included a significant shift in the abundance and proportion of bacterial phyla (Planctomycetes, Firmicutes, Bacteroidetes, Spirochaetes, Tenericutes, Proteobacteria, and Cyanobacteria) and fungal phyla (Chytridiomycota, Mortierellomycota, Neocallimastigomycota, Ascomycota, and Basidiomycota) across all development stages in yaks. As yaks grew older, variation reduced, and diversity increased as compared to young yaks. In addition, the intestine was colonized by a succession of microbiomes that coalesced into a more mature adult, including Ruminococcaceae_UCG-005, Romboutsia, Prevotellaceae_UCG-004, Blautia, Clostridium_sensu_stricto_1, Ruminococcus_1, Ruminiclostridium_5, Rikenellaceae_RC9_gut_group, Alloprevotella, Acetitomaculum, Lachnospiraceae_NK3A20_group, Bacteroides, Treponema_2, Olsenella, Escherichia-Shigella, Candidatus_Saccharimonas, and fungal communities Mortierella, Lomentospora, Orpinomyces, and Saccharomyces. In addition, microorganisms that threaten health, such as Escherichia-Shigella, Mortierella, Lomentospora and Hydrogenoanaerobacterium, Corynebacterium_1, Trichosporon, and Coprinellus, were enriched in young and old yaks, respectively, although all yaks were healthy. The significant shifts in microflora composition and structure might reflect adaptation of gut microbiome, which is associated with physicochemical conditions changes and substrate availability in the gut across all development periods of yaks.

Accelerated Aging of Vulcanized Rubber. Factors Determining the Relation between Oven and Bomb Aging

1947 ◽  
Vol 20 (3) ◽  
pp. 760-768 ◽  
Author(s):  
R. G. Newton ◽  
J. R. Scott
Keyword(s):  
Accelerated Aging ◽  
Natural Aging ◽  
Relative Importance ◽  
Temperature Coefficients ◽  
Vulcanized Rubber ◽  
Relative Response ◽  
Aging Conditions ◽  
Moderate Range ◽  
Natural Rubber Vulcanizates ◽  
Theoretical Considerations

Abstract A study has been made of the influence of the following factors on the relative rates of tensile deterioration of natural rubber vulcanizates in the Geer oven and oxygen bomb, both at 70° C : period of vulcanization, sulfur ratio, nature of accelerator. Expressing this relation as the oven/bomb ratio, i.e., the ratio between oven and bomb aging periods that give the same deterioration, the following conclusions are drawn. (1) Varying the period of vulcanization of a given mix over a moderate range (2:3) around the optimum does not noticeably alter the oven/bomb ratio, except in unaccelerated mixes, where overvulcanization gave an abnormally low ratio, owing to the rubber perishing very rapidly in the oven. (2) The effect of varying the sulfur ratio within the usual limits for soft rubbers is small, and appears to result from the quicker vulcanization of the mixes richer in sulfur. (3) The nature of the accelerator profoundly affects the ratio, values ranging from 3 to 27 being found among the present mixes ; this effect is believed to be exerted through the influence of the accelerator both on rate of vulcanization and on the oxidizability of the vulcanizate. Theoretical considerations indicate that a rubber which vulcanizes quickly and (or) oxidizes slowly should give a low oven/bomb ratio, whereas one that vulcanizes slowly and(or) oxidizes quickly should give a higher ratio. The experimental data are generally in accord with this, and there is evidence that both rate of vulcanization and oxidizability can have an important effect, but the data do not enable the separate effect of each to be assessed exactly. The bearing of the results on the use of the oven and bomb tests is briefly discussed. It is shown that they demonstrate the fallacy of using a single factor for converting oven to bomb aging periods or vice versa, and that the relative natural aging resistances of widely different vulcanizates cannot be reliably assessed by either test, a limitation arising from the fact that the relative importance of oxidative decay and aftervulcanization varies from one type of mix to another, and that the temperature coefficients of these processes are not necessarily the same. These facts are very important in relation to the choice and application of accelerated aging tests for specification purposes, since these usually have to be applied to rubbers of unknown compositions, which are likely to vary widely in their relative response to different aging conditions.

scholarly journals Quantitative Trait Locus Mapping of Seed Vigor in Soybean under −20 °C Storage and Accelerated Aging Conditions via RAD Sequencing

2021 ◽  
Vol 43 (3) ◽  
pp. 1977-1996
Author(s):  
Rongfan Wang ◽  
Fengqi Wu ◽  
Xianrong Xie ◽  
Cunyi Yang
Keyword(s):  
Quantitative Trait ◽  
Accelerated Aging ◽  
Natural Aging ◽  
Storage Conditions ◽  
Seed Vigor ◽  
C Storage ◽  
Poor Seed ◽  
Aging Conditions ◽  
Trait Locus ◽  
Locus Mapping

Due to its fast deterioration, soybean (Glycine max L.) has an inherently poor seed vigor. Vigor loss occurring during storage is one of the main obstacles to soybean production in the tropics. To analyze the genetic background of seed vigor, soybean seeds of a recombinant inbred line (RIL) population derived from the cross between Zhonghuang24 (ZH24, low vigor cultivar) and Huaxia3hao (HX3, vigorous cultivar) were utilized to identify the quantitative trait loci (QTLs) underlying the seed vigor under −20 °C conservation and accelerated aging conditions. According to the linkage analysis, multiple seed vigor-related QTLs were identified under both −20 °C and accelerated aging storage. Two major QTLs and eight QTL hotspots localized on chromosomes 3, 6, 9, 11, 15, 16, 17, and 19 were detected that were associated with seed vigor across two storage conditions. The indicators of seed vigor did not correlate well between the two aging treatments, and no common QTLs were detected in RIL populations stored in two conditions. These results indicated that deterioration under accelerated aging conditions was not reflective of natural aging at −20 °C. Additionally, we suggest 15 promising candidate genes that could possibly determine the seed vigor in soybeans, which would help explore the mechanisms responsible for maintaining high seed vigor.

Processing of V65 Aluminium Alloy Wires Processed from Hot and Warm Rolled Rods for Rivet Applications

2012 ◽  
Vol 710 ◽  
pp. 174-179
Author(s):  
Niraj Nayan ◽  
S.V.S. Narayana Murty ◽  
S.C. Sharma ◽  
Parameshwar Prasad Sinha
Keyword(s):  
Aluminium Alloy ◽  
Vacancy Concentration ◽  
Natural Aging ◽  
High Plasticity ◽  
Potential Candidate ◽  
2024 Alloy ◽  
Treat Ment ◽  
Aa 2024 ◽  
Aging Kinetics

High shear strength of 25 kg/mm2 combined with a high plasticity makes Russian grade V65 aluminum alloys as potential candidate compared to AA2024 for riveting applications in aerospace industries. The lower content of magnesium over the AA 2024 alloy decreases the aging kinetics of this alloy because of the decreased vacancy concentration in the as-quenched alloy which in turn gives flexibility to carryout riveting operation even after 4 days after solution heat treat¬ment and natural aging at room temperature. This paper presents the processing and characterization of V65 aluminium alloy wires processed from hot and warm rolled rods. Mechanical properties of the wires have been evaluated in T6 and T4 tempers and correlated with microstructures. Detailed microstructural examination using optical microscopy and fractography of the tensile tested samples using scanning electron microscopy were carriedout.

scholarly journals Proteome-Wide Characterization of Seed Aging in Arabidopsis: A Comparison between Artificial and Natural Aging Protocols

2008 ◽  
Vol 148 (1) ◽  
pp. 620-641 ◽  
Author(s):  
Loïc Rajjou ◽  
Yoann Lovigny ◽  
Steven P.C. Groot ◽  
Maya Belghazi ◽  
Claudette Job ◽  
...  
Keyword(s):  
Natural Aging ◽  
Seed Aging

Effect of Aging Precipitates on the Bendability of an Al-Mg-Si Alloy

2014 ◽  
Vol 794-796 ◽  
pp. 572-577 ◽  
Author(s):  
Hidetaka Nakanishi ◽  
Mineo Asano ◽  
Hideo Yoshida
Keyword(s):  
Shear Bands ◽  
Natural Aging ◽  
Bending Test ◽  
Heat Radiation ◽  
Plate Material ◽  
Bake Hardening ◽  
Β Phase ◽  
Phase Precipitate ◽  
Aging Conditions ◽  
Better Than

Al-Mg-Si alloys are usually applied a T4 temper as the plate material for automobile bodies due to the necessity of a high bake hardening property. Many reports about the improvement in the bendability of Al-Mg-Si alloys applied a T4 temper have been published, because they easily crack during the hemming process. On the other hand, Al-Mg-Si alloys applied T6 and T7 tempers are used as the material of wiring plates and heat radiation devices. A high electrical conductivity and good bendability are necessary for these devices. In this study, the effect of the aging conditions on the bendability was investigated. As a result, the bendability at the T6 temper significantly decreased. The bendability under the aging temper, and over the aging temper was better than that at the T6 temper. Samples treated by natural-aging at high temperature before the T6 temper easily cracked during the bending test. It was postulated that the formation of shear bands was significant and the bendability decreased during the bending test under the high density and fine β phase precipitate conditions.

scholarly journals Effects of Mg, Si contents and natural aging conditions on the bake hardenability of Al-Mg-Si alloys

2004 ◽  
Vol 54 (10) ◽  
pp. 412-417 ◽  
Author(s):  
Hidenori HATTA ◽  
Hiroki TANAKA ◽  
Shinichi MATSUDA ◽  
Hideo YOSHIDA
Keyword(s):  
Natural Aging ◽  
Aging Conditions ◽  
Bake Hardenability
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