نتایج جستجو برای: aging time
تعداد نتایج: 1980703 فیلتر نتایج به سال:
the role played by soil constituents in governing temporal trends of metal mobility in calcareousmediterranean soils deserves special attention due to the particular soil and climate characteristics. reactionsoccurring during the aging modify the metal mobility over time, and the rate of metal application and type ofsoil can be decisive in the outcome of aging reactions in soils. the aim of the...
A facile effective stirring aging at room temperature prior to conventional hydrothermal treatment was employed in the template-free synthesis of micro- and nano-crystalline sodalites with two different initial gel compositions. The effect of initial Si/Al molar ratio, NaOH concentration and stirring aging time were investigated on the morphology and particle size of the...
In order to aging study of the compsite solid propellants, usually the changes in propellant properties during warehousing and storage are measured, and then the shelf life of them estimated. In this regard, by applying the common methods based on mechanical tests, chemical and thermal analysis, the propellant properties due to aging and time lapse are measured. In this paper, first we remark t...
use of plant growth promoting bacteria (pgpb) and high quality of seed as agricultural inputs play important roles in sustainable crop production. to study the effects of different levels of seed aging and pgpb's application on field emergence, seedling establishment and yield of two red kidney bean cultivars in field conditions, an experiment was carried out as factorial based in a rcbd d...
We removed from the Penna model for biological ageing any random killing Verhulst factor. Deaths are due only to genetic diseases and the population size is fixed, instead of fluctuating around some constant value. We show that these modifications give qualitatively the same results obtained in an earlier paper, where the random killings (used to avoid an exponential increase of the population)...
Objectives: Perception of ageing has been introduced as an independent predictor of functional disability and mortality in older adults. The present study aimed to investigate the perception of aging in the literature and reach a more comprehensive understanding of this concept. Methods & Materials: A comprehensive search of electronic databases of ProQuest, Web of Science, CINAHL,&n...
the effects of isothermal aging at temperatures between 550-850 ?c for durations of 1-100 h on microstructure, tensile properties, and impact fracture behavior of 316l austenitic stainless steel weld metal have been investigated. for this purpose, various techniques including metallographic observations, measurement of ferrite content using ferritscope, and fractographic investigations have bee...
objective: despite the high strength of zirconia restorations, aging in the oral environment and masticatory loading may result in transformation of tetragonal to monoclinic phase and decrease their strength. statements in this regard are controversial. this study sought to compare the flexural strength (fs) of zirkonzahn (zirkonzahn, cercon, ceramill) and mamut (dubai medical equipment llc, du...
Propellants are decomposed slowly during storage. So each propellant has useful life time which more than that time propellant is not safe and cannot used. Tracing of propellant stabilizer consumption is one of the important methods for determination of storage life time period of a propellant. In this article by accelerated aging on a double-base propellant and then chemical extraction of stab...
several samples of mesoporous silica were prepared via sol-gel chemistry in the presence of ctab as template with variation of stirring intensity and aging time, ratios of ctab/sio2 and nh4oh/h2o in synthesis mixture. effects of aging temperature, hydrothermal treatment and ter-butanol addition to the synthesis mixture on the textural properties of obtained samples were also studied. results of...
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