نتایج جستجو برای: aerogel

تعداد نتایج: 1852  

2002
Priya Sharma

We report theoretical calculations of the thermal conductivity of superfluid He impregnated into high-porosity aerogel and compare these results with available experimental data.

2017
Qiufang Yao Bitao Fan Ye Xiong Chunde Jin Qingfeng Sun Chengmin Sheng

Cellulose nanofibril/graphene oxide hybrid (CNF/GO) aerogel was fabricated via a one-step ultrasonication method for adsorptive removal of 21 kinds of antibiotics in water. The as-prepared CNF/GO aerogel possesses interconnected 3D network microstructure, in which GO nanosheets with 2D structure were intimately grown along CNF through hydrogen bonds. The aerogel exhibited superior adsorption ca...

Journal: :Nanoscale 2015
Pin Hao Zhenhuan Zhao Liyi Li Chia-Chi Tuan Haidong Li Yuanhua Sang Huaidong Jiang C P Wong Hong Liu

Current applications of carbon-based supercapacitors are limited by their low energy density. One promising strategy to enhance the energy density is to couple metal oxides with carbon materials. In this study, a porous MnCo2O4.5 nanoneedle/carbon aerogel hybrid nanostructure was synthesized by assembling MnCo2O4.5 nanoneedle arrays on the surface of channel walls of hierarchical porous carbon ...

1998
J. M. Parpia

We have examined the superfluidity of 3He in 98.2% porous silica aerogel with up to 34% 4He at 21.6 bars. The mixture is phase separated for 4He fractions between ,11% and 34%, and the 4Herich phase preferentially occupies the regions of highest silica density in the aerogel, thus modifying the distribution of the correlated disorder seen by superfluid 3He. The 3He Tc increases slightly with 4H...

2017
Pierre Hunger Yuriy M. Bunkov Eddy Collin Henri Godfrin H. Godfrin

The phenomenon of phase-coherent precession of magnetization in superfluid He and the related effects of spin superfluidity are based on the true Bose-Einstein condensation of magnons. Several different states of coherent precession have been observed in He-B: homogeneously precessing domain (HPD); persistent signal formed by Q-balls at very low temperatures; coherent precession with fractional...

Journal: :journal of nanostructures 2013
a. tadjarodi m. haghverdi v. mohammadi m. rajabi

the silica aerogel was prepared by the acid–base sol–gel polymerization of tetraethylorthosilicate precursor followed by ambient pressure drying. the prepared silica aerogels were characterized by fourier transform infrared )ft-ir(, thermo-gravimetric and differential thermal analysis )tg/dta(, x-ray diffractometer )xrd(, energy dispersive x-ray microanalysis )edx(, brunauer–emmitt–teller (bet)...

Journal: Polyolefins Journal 2015

Monolithic aerogels of high molecular weight polyethylene (Mw= 3x106- 6x106 g/mol) have been prepared by solvent extraction with supercritical carbon dioxide from thermoreversible gels prepared in decalin. These low density and highly porous aerogels present an apparent porosity up to 90%. The aerogel morphology observed by scanning electron microscopy (SEM) is characterized by spherulitic stru...

Journal: :Chemical Engineering Journal 2022

Polymer aerogels are a promising, non-brittle alternative to silica aerogel, but limited by their very poor high-temperature stability. Polyimide is widely known for its high heat-resistance, however, degree of volume shrinkage common polyimide after exposure temperatures above 200 °C. Here, we present the aerogel-in-aerogel composites that comprise aerogel grains with nanoparticulate microstru...

Journal: Journal of Nanoanalysis 2017
Hossein Afkhami Abadani Jamal Davarpanah, Mohamad Mehdi Seraji Sadra Soleimankhani,

Phenol-formaldehyde/silica hybrid gel with hydrophobic character, high porosity, and thesmall pore size mean was prepared via sol-gel polymerization under solvent saturated vaporatmosphere and was dried by ambient drying method. The silica sols were prepared based onTetraethoxysilane (TEOS) and Methyltrimethoxysilane (MTES) as hydrophilic and hydrophobicprecursors, respectively. Phenol-formalde...

2009
D. E. Brownlee D. Joswiak G. Matrajt S. Messenger

Introduction: One of the most remarkable findings from of the study of comet samples returned by the Stardust mission is the apparent scarcity of pre-solar grains. Unlike common expectations, the abundance of pre-solar grains in comet Wild 2 appears to be less than in primitive meteorites, micrometeorites and IDPs. The best measurements of the abundances of isotopically anomalous pre-solar grai...

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