نتایج جستجو برای: aerogel
تعداد نتایج: 1852 فیلتر نتایج به سال:
Introduction: Silica aerogel is an ultra-lowdensity glass foam used in collector tiles for the capture of particles in low Earth orbit [1] and, recently, for the capture of cometary particles by NASA’s Stardust mission [2]. Reliable and reproducible methods for cutting these and future collector tiles from sample return missions are necessary to enable detailed study of the captured material. T...
ethylene polymerization was carried out using phillips chromium catalyst based on silica supports such as silicaaerogel, sio2 (grace 643), and titanium modified sio2 (g 643), and the results were compared with othercatalysts based on sio2 (aldrich), sba-15(hex), sba-15(sp) and mcm-41. a combination of tga, dsc, xrd,nitrogen adsorption, sem, icp, ftir and other analyses were used to characterize...
Graphene aerogel materials have attracted increasing attention owing to their large specific surface area, high conductivity and electronic interactions. Here, we report for the first time a novel strategy for the synthesis of nitrogen-doped activated graphene aerogel/gold nanoparticles (N-doped AGA/GNs). First, the mixture of graphite oxide, 2,4,6-trihydroxybenzaldehyde, urea and potassium hyd...
Positronium yield using the “3γ method” and lifetime measurements were performed at cryogenic and room temperature by means of a variable energy positron beam in homogeneous porous silica (Aerogel). An estimation of the positronium (Ps) mean diffusion length was obtained by measuring capped samples. An efficient formation of cooled Ps atoms is a requisite for the production of antihydrogen, wit...
Silica aerogels functionalized with strongly fluorescent carbon quantum dots were first prepared and used for simple, sensitive, and selective sensing of NO2 gas. In the presence of ethanol, homemade silica aerogels with a large specific surface area of 801.17 m(2)/g were functionalized with branched polyethylenimine-capped quantum dots (BPEI-CQDs) with fluorescence quantum yield higher than 40...
Within the phenomenological approach a criterion for a choice of the order parameter of the superfluid phases of 3 He in aerogel in a vicinity of the transition temperature is derived. The order parameter of bulk B-phase of 3 He meets this criterion and that of the bulk A-phase doesn't. A class of order parameters of Equal Spin Pairing (ESP) type meeting the derived criterion is discussed. Orde...
Within a phenomenological approach possible forms of the order parameter of the superfluid phases of 3He in a vicinity of the transition temperature are discussed. Effect of aerogel is described by a random tensor field interacting with the orbital part of the order parameter. With respect to their interaction with the random tensor field a group of ”robust” order parameters which can maintain ...
This paper describes the development of a threshold type aerogel Čerenkov counter with a large sensitive area of 0.6m to be carried onboard the BESS rigidity spectrometer to detect cosmic-ray antiprotons. The design incorporates a large diffusion box containing 46 finemesh photomultipliers, with special attention being paid to achieving good performance under a magnetic field and providing suff...
The photoluminescence features of Eu(3+)-, Tb(3+)-, Tb(3+)/Eu(3+)-alginate aerogel (hydrogel and alcogel) and Eu(3+)-alginate xerogel hybrids were investigated. The Eu(3+)-alginate aerogel and alcogel exhibit the highest (5)D0 quantum efficiencies (9.9 and 8.2%, respectively), while the hydrogel and xerogel have lower values (5.2 and 5.6%, respectively). The Tb(3+)/Eu(3+) hybrids are multiwavel...
Reduced graphene oxide-magnetite hybrid aerogels attract great interest thanks to their potential applications, e.g., as magnetic actuators. However, the tendency of magnetite particles to migrate within the matrix and, ultimately, escape from the aerogel structure, remains a technological challenge. In this article we show that coating magnetite particles with polydopamine anchors them on grap...
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