Trowelable Rubber Rocket Insulation for Use at 2800°C

1984 ◽  
Vol 57 (4) ◽  
pp. 843-854 ◽  
Author(s):  
J. G. Sommer
Keyword(s):  
Room Temperature ◽  
Loss Rate ◽  
Service Temperature ◽  
Material Loss ◽  
Blowing Agent ◽  
Unusual Combination ◽  
Novel Approaches ◽  
Glass Microballoons ◽  
Burning Propellant ◽  
Intense Heat

Abstract Ablative, trowelable rocket insulation was prepared; it crosslinks at room temperature and self-bonds to prevulcanized NBR insulation. The material loss rate (MLR) of this insulation is low when it is tested by an oxyacetylene torch at temperatures of about 2800°C. Boric acid in the insulation causes an effective char to form at service temperature. This char slows the loss rate of nondegraded insulation beneath it. Density of this nondegraded insulation is 1.3 g/cm3. Density is reduced sharply to 0.8 g/cm3 by incorporating glass microballoons. They cause only a slight increase in MLR of the insulation at service temperatures. MLR can be significantly reduced by incorporating a blowing agent which decomposes only after the insulation is exposed to service temperature. Hence, an unusual combination of requirements is met by several novel approaches. This insulation has protected rockets as large as 6.6 meters in diameter from the intense heat of burning propellant in service.

Experiment and Optimization of High-Efficiency Mechanical Separation of Peanut Seedlings and Residual Film Based on Suspension Velocity

2021 ◽  
Vol 64 (4) ◽  
pp. 1381-1389
Author(s):  
Fengwei Gu ◽  
Meng Yang ◽  
Zhichao Hu ◽  
Yanhua Zhang ◽  
Chong Zhang ◽  
...  
Keyword(s):  
Moisture Content ◽  
Rotational Speed ◽  
Loss Rate ◽  
Removal Rate ◽  
Performance Tests ◽  
Test Results ◽  
Material Loss ◽  
Validation Test ◽  
Residual Film ◽  
Forage Utilization

HighlightsAn efficient method for separating peanut seedlings and residual film harvested from film-mulched peanut was proposed, and the mechanism was optimized.The relationships between the suspension velocity and moisture content of different shredded materials were studied.Four-factor, three-level Box-Behnken experiments were carried out and analyzed, and the optimal parameter combination was determined.A validation test was carried out to verify the rationality and accuracy of the optimized regression model.Abstract. To address the problems of lower residual film removal and higher material loss in the forage utilization of peanut seedlings wrapped in residual film, this study explored the relationships between the suspension velocity and moisture content of different shredded materials derived from peanut seedlings and conducted performance tests and parameter optimization for a machine that uses peanut seedlings as forage material. Four-factor, three-level Box-Behnken experiments were designed using the rotational speeds of the shredding shaft, upper fans, and lower fans and the frequency of the vibrating sieve as test factors, and using the residual film removal rate and material loss rate as response values. The test results indicated that the suspension velocity of the shredded materials showed a quadratic relationship with moisture content. The performance tests showed that the significance sequence of the test factors for the residual film removal rate was: rotational speed of the lower fans, rotational speed of the upper fans, rotational speed of the shredding shaft, and frequency of the vibrating sieve. The significance sequence for the material loss rate was: rotational speed of the lower fans, rotational speed of the shredding shaft, frequency of the vibrating sieve, and rotational speed of the upper fans. The parameter optimization and validation test showed that the residual film removal rate was 92.71% and the material loss rate was 8.19% when the rotational speeds of the shredding shaft, upper fans, and lower fans were 1650, 770, and 665 rpm, respectively, and the frequency of the vibrating sieve was 4 Hz. The relative errors between the validation test results and the predicted values from the regression models were less than 3%, which suggests that the regression models are reliable. This study provides a reference for the forage utilization of peanut seedlings harvested from film-mulched peanut and provides a reference for determining the optimal working parameters of forage processing machines. Keywords: Agricultural machinery, Box-Behnken experiment, Optimization, Peanut film-seedling separation, Suspension velocity.

Synthesis and Structural Systematics of Nitrogen Base Adducts of Group 2 Salts. I. Some Adducts of Group 2 Halides With Acetonitrile

1996 ◽  
Vol 49 (1) ◽  
pp. 27 ◽  
Author(s):  
AF Waters ◽  
AH White
Keyword(s):  
Coordination Sphere ◽  
Molecular Species ◽  
Room Temperature ◽  
Linear Array ◽  
Nitrogen Base ◽  
X Ray ◽  
Unusual Combination ◽  
Anionic Species ◽  
Group 2 ◽  
O 352

Recrystallization of anhydrous Group 2 halides from anhydrous acetonitrile has yielded, in a number of cases, adducts MX2.nMeCN suitable for characterization by room-temperature single-crystal X-ray studies, which revealed novel stereochemical types. Magnesium(II) bromide yields a trisolvate, ionic with disproportionated ligand arrays, as [Mg(NCMe)6][MgBr4] (1), an unusual combination of homoleptic cationic and anionic species. Crystals are triclinic, Pī , a 19.129(1), b l6.870(8), c 8.737(7) Ǻ,α 83.96(3), β 87.93(4), γ 65.24(2)�, Z=4 f.u .; R was 0.068 for N o 3181 'observed' (I > 3σ(I)) reflections. Mg-N are 2.12(2)-2.18(2) Ǻ, and Mg-Br are 2.452(7)-2.481(6) Ǻ. Calcium(II) bromide, by contrast, yields a disolvate , an infinite polymer, with the two MeCN ligands trans in a quasi-octahedral coordination sphere, and the polymer comprising a ... Ca(μ-Br)2Ca(μ-Br)2... linear array. Crystals of 1:2 CaBr2/MeCN (2) are orthorhombic, Pbam , a l4.252(3), b 8.539(2), c 4.2088(6) Ǻ, Z=2 f.u .; R 0.043 for N o 352. Ca-N is 2.46(1) Ǻ, and Ca-Br 2.8765(9) Ǻ. CaI2 and SrI2 yield pentasolvates as neutral, molecular species [( MeCN )5MX2] (3) and (4), with the halides trans in a pentagonal bipyramidal coordination sphere. They are isomorphous . orthorhombic, Pcab , a ≈ 18.4, b ≈ 14.6, c ≈ 14.3 Ǻ, Z = 8 f.u .; R were 0.042 and 0.059 for N o 2297 and 1489 respectively. Ca-I are 3.132(2), 3.116(2) Ǻ and Sr -I are 3.265(3), 3.238(3) Ǻ, while Ca-N are (range) 2.518(8)-2.566(8) Ǻ and Sr -N 2.68(2)-2.73(2) Ǻ.

scholarly journals Biocontrol of Pear Postharvest Decay by Kombucha

2019 ◽  
Vol 47 (3) ◽  
Author(s):  
Junping TAN ◽  
Xian ZHOU ◽  
Shuiyuan CHENG ◽  
Zexiong CHEN ◽  
Yuanyuan GOU ◽  
...  
Keyword(s):  
Weight Loss ◽  
Electric Conductivity ◽  
Room Temperature ◽  
Loss Rate ◽  
Economic Benefits ◽  
Control Group ◽  
Pear Fruit ◽  
Weight Loss Rate ◽  
Post Harvest ◽  
Mda Content

Kombucha is sweetened, slightly alcoholic, and lightly effervescent tea drink. Its acidity inhibits the growth of harmful bacteria. Here, we studied effect of kombucha on post-harvest preservation of pear. The Hosui pears were soaked with the kombucha for 15 minutes, and in distilled water as the control, respectively. Superoxide dismutase (SOD), peroxidase (POD), malondialdehyde (MDA), hydrogen peroxide (H2O2), proline content, electric conductivity, weight loss rate and good fruit rate in pear were measured during storage at room temperature. The results showed that the kombucha could effectively prolong the storage time of pear fruit. The fruit quality of the treated group was 1.5 times higher than that of the control pear fruit when stored at room temperature for 18 days. The weight loss rate, MDA content and electric conductivity of the treatment group were lower than those of the control group during the whole storage period, indicating that kombucha can inhibit the transformation of polysaccharides such as starch and pectin, and delay the degradation of nutrients in the fruit, resulting in a decrease in weight loss rate, inhibition of membrane lipid peroxidation, reducing MDA content, electric conductivity, maintaining cell membrane stability, delaying pear fruit senescence. Kombucha can inhibit the content of H2O2 and proline, increase the activity of POD and SOD increase the storage stability of fruits. The purpose of this study was to elucidate the physiological mechanism of post-harvest preservation of pear by kombucha. The use of kombucha can prolong the supply period of pear, increase economic benefits and expand the market of pear.   ********* In press - Online First. Article has been peer reviewed, accepted for publication and published online without pagination. It will receive pagination when the issue will be ready for publishing as a complete number (Volume 47, Issue 3, 2019). The article is searchable and citable by Digital Object Identifier (DOI). DOI link will become active after the article will be included in the complete issue. *********

Research on Shrinkage Chemical Properties of Cement Stabilized Macadam Material Based on a Multi-dimensional Expansion and Shrinkage Tester

2020 ◽  
Vol 71 (6) ◽  
pp. 418-428
Author(s):  
Aiping Fei ◽  
Wensheng Zhang ◽  
Tiezhi Zhang
Keyword(s):  
Water Loss ◽  
Room Temperature ◽  
Loss Rate ◽  
Chemical Properties ◽  
Shrinkage Strain ◽  
Fine Aggregate ◽  
Water Loss Rate ◽  
Dry Shrinkage ◽  
Reflection Crack ◽  
Shrinkage Coefficient

In order to find out the shrinkage law of cement stabilized macadam material under specific conditions, this paper studied the expansion and shrinkage properties of cement stabilized macadam material under two environmental conditions, five kinds of cement dosage conditions, suspended compacted type and skeleton compaced type based on the multi-dimensional expansion and shrinkage tester. Through the test comparison, it is confirmed that the water loss rate of cement stabilized macadam material increases with the increase of cement dosage, showing a general change rule of rising first and then stabilizing. The average increase of the total water loss rate of suspended compacted cement stabilized macadam at room temperature was greater than that of the skeleton compacted cement stabilized macadam. The dry shrinkage strain also follows the above trend. Either at room temperature or under the conditions of dry shrinkage box, the water loss rate of suspended compacted cemeny stabilized macadam is higher than that of skeleton compacted cement stabilized macadam , which can be up to 3.23% higher. By comparing the temperature shrinkage coefficient under the high and low temperature environment, the temperature coefficient of the skeleton compacted cement stabilized macadam is smaller than that of the suspended compacted cement stabilized macadam. The temperature shrinkage coefficient of the suspended compacted cement stabilized macadam increases by 5.56% on average for each 0.5% increase of the cement dosage, and the temperature shrinkage coefficient of the skeleton compacted cement stabilized macadam increases by 6.33% on average. Through the comparative analysis of tests, it can be found that the anti-reflection crack ability of the skeleton compacted cement stabilized macadam material is better, and the fine aggregate content should be strictly controlled in the construction.

Analysis the Application of Environmental Properties of SO2 Fungicide for Extended Storage Life of Muscate Table Grapes at Room Temperature

2012 ◽  
Vol 600 ◽  
pp. 33-38
Author(s):  
Hui Ye Duan ◽  
Wen Cai Xu ◽  
Dong Li Li ◽  
Ya Bo Fu ◽  
Jing Yong Zhang
Keyword(s):  
Decay Rate ◽  
Water Loss ◽  
Room Temperature ◽  
Loss Rate ◽  
Transmission Rate ◽  
Control Group ◽  
Water Loss Rate ◽  
Table Grapes ◽  
Environmental Properties ◽  
Significant Difference

The germicidal bags which can release environmental properties of SO2 fungicide, have lower water vapor transmission rate and higher oxygen transmission rate, and theirs effect on preservation of table grapes was investigated during storage at room temperature. The results showed that germicidal bags were able to maintain physicochemical, and physiological quality of grapes at a higher level compared with the common LDPE bags. At 16th days, decreases in the water loss rate, berry decay rate, and contents of total soluble solids, titratable acidity of germicidal bags groups were significantly inhibited. Although the content of TSS, TA and the berry firmness didn't show the significant difference between the germicidal bags and control group, but decay rate, shatter rate, and water loss rate of the control group were increased to 5.01%, 13.58%, and 0.67%, respectively. The control group had lost edible value. The overall results expressed that grapes quality can be maintained effectively at least for 16 days using germicidal bags.

Fresh-Keeping Effect of Kojic Acid on Rape

2013 ◽  
Vol 774-776 ◽  
pp. 695-698
Author(s):  
Xi Zhang ◽  
Yu Ting Dong ◽  
Jiang Sen Pei ◽  
Tao Han ◽  
Bei Guo
Keyword(s):  
Dry Matter ◽  
Room Temperature ◽  
Fruits And Vegetables ◽  
Loss Rate ◽  
Kojic Acid ◽  
Water Evaporation ◽  
Weight Loss Rate ◽  
Natural Preservative ◽  
Phenotypic Changes ◽  
Slowing Down

Kojic acid is a metabolite from some common microbe, it is a natural preservative. The kojic acid has broad prospects in the storage and preservation of fruits and vegetables. In this study, using different concentrations of kojic acid sprayed the surface of rape and stored at room temperature, observed phenotypic changes. Then the CAT and POD activity, chlorophyll content and weight loss rate were determined in rape treated by kojic acid. From the overall trend, compared with the water, spraying 0.5% and 1% kojic acid to a certain extent reduce chlorophyll loss of rape, water evaporation and dry matter decrease was slowing down, and maintains the appropriate activity of CAT and POD. It means that the kojic acid has obviously effect on rape preservation.

Intercalation of Sodium-Potassium Alloys Into Graphite

1998 ◽  
Vol 548 ◽  
Author(s):  
L. Antoine ◽  
J.C. Gachon ◽  
D. Guerard
Keyword(s):  
Alkali Metal ◽  
Metal Content ◽  
Room Temperature ◽  
Gas Purification ◽  
Sodium Potassium ◽  
Graphene Layers ◽  
Polymerization Catalyst ◽  
High Alkali ◽  
Intense Heat

ABSTRACTThe intercalation, at room temperature, of the sodium-potassium eutectic into graphite is performed, in a glove box under purified argon. It leads to a high alkali metal content powder. The annealing under vacuum, at 200°C for two days leads to a pure first stage compound whose formula is NaK2C12 with a color and a structure close to that of KC8. This phase is unstable and decomposes slowly in a mixture of KC8 and free alloy. However, this free alloy, which is liquid at room temperature, remains as inclusions between the graphene layers and the compound remains as a powder which can be useful for some applications when one needs large quantities of an alkali metal “solid” at room temperature, e.g. for gas purification (it reacts with oxygen and with moisture), for rapid and intense heat provider (it burns in air and the carbon is also participating to the heating), for ionic polymerization catalyst…

SONOS memory devices with ion beam modified nitride layers

2012 ◽  
Vol 1430 ◽  
Author(s):  
D. Simatos ◽  
P. Dimitrakis ◽  
V. Ioannou-Sougleridis ◽  
P. Normand ◽  
K. Giannakopoulos ◽  
...  
Keyword(s):  
Room Temperature ◽  
Loss Rate ◽  
Ion Beam ◽  
Memory Window ◽  
Electron Loss ◽  
Gate Stacks ◽  
Pulse Regime ◽  
Transmission Electron ◽  
Nitride Layers ◽  
Nitride Oxide

ABSTRACTIn this work we examine the development of ion beam modified oxide-nitride-oxide structures formed by low-energy (1 keV) implantation of Si, N and Ar ions (1x1016 ions/cm2) into oxide-nitride gate stacks and subsequent wet-oxidation to form the blocking oxide. Transmission electron microscopy indicates that the thickness of the blocking oxide layer is strongly affected by the implantation process going from 1 nm (non-implanted sample) to 4-5 nm (N and Ar implants) and 7.5 nm (Si implant). The Si implanted stacks exhibit the highest attainable memory window (∼ 8.5 V for a 1 ms pulse regime), which involve both electron and hole storage. In contrast the thinner blocking oxide that develops to the nitrogen and argon implanted stacks limits the memory window which is due only to electron trapping. Room temperature charge retention measurements of the programming state reveal that the electron loss rate is faster in samples implanted with Si than N, allowing for a memory window of 1.7 V and 2.5 V respectively after ten years extrapolation. This retention behavior is mainly attributed to the different nature of the traps generated in the implanted materials.

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