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1

ANALYSIS AND TESTING OF MULTILAYER AND AEROGEL INSULATION CONFIGURATIONS  

Microsoft Academic Search

Multilayer insulation systems that have robust operational characteristics have long been a goal of many research projects. Such thermal insulation systems may need to offer some degree of structural support and?or mechanical integrity during loss of vacuum scenarios while continuing to provide insulative value to the vessel. Aerogel-based composite blankets can be the best insulation materials in ambient pressure environments;

W. L. Johnson; J. A. Demko; J. E. Fesmire

2010-01-01

2

Analysis and Testing of Multilayer and Aerogel Insulation Configurations  

Microsoft Academic Search

Multilayer insulation systems that have robust operational characteristics have long been a goal of many research projects. Such thermal insulation systems may need to offer some degree of structural support and\\/or mechanical integrity during loss of vacuum scenarios while continuing to provide insulative value to the vessel. Aerogel-based composite blankets can be the best insulation materials in ambient pressure environments;

W. L. Johnson; Jonathan A Demko; J. E. Fesmire

2010-01-01

3

Aerogel-Based Insulation for Industrial Steam Distribution Systems  

SciTech Connect

Thermal losses in industrial steam distribution systems account for 977 trillion Btu/year in the US, more than 1% of total domestic energy consumption. Aspen Aerogels worked with Department of Energy’s Industrial Technologies Program to specify, develop, scale-up, demonstrate, and deliver Pyrogel XT®, an aerogel-based pipe insulation, to market to reduce energy losses in industrial steam systems. The product developed has become Aspen’s best selling flexible aerogel blanket insulation and has led to over 60 new jobs. Additionally, this product has delivered more than ~0.7 TBTU of domestic energy savings to date, and could produce annual energy savings of 149 TBTU by 2030. Pyrogel XT’s commercial success has been driven by it’s 2-4X better thermal performance, improved durability, greater resistance to corrosion under insulation (CUI), and faster installation times than incumbent insulation materials.

John Williams

2011-03-30

4

Aerogel Based Insulation for High Temperature Industrial Processes.  

National Technical Information Service (NTIS)

Under this program, Aspen Aerogels has developed an industrial insulation called Pyrogel HT, which is 4-5 times more thermally efficient than current non-aerogel technology. Derived from nanoporous silica aerogels, Pyrogel HT was specifically developed to...

O. Evans

2011-01-01

5

Method of fabricating a multilayer insulation blanket  

Microsoft Academic Search

An improved multilayer insulation blanket for insulating cryogenic structures operating at very low temperatures is disclosed. An apparatus and method for fabricating the improved blanket are also disclosed. In the improved blanket, each successive layer of insulating material is greater in length and width than the preceding layer so as to accommodate thermal contraction of the layers closest to the

John D. Gonczy; Ralph C. Niemann; William N. Boroski

1993-01-01

6

Multilayer insulation blanket, fabricating apparatus and method  

Microsoft Academic Search

An improved multilayer insulation blanket for insulating cryogenic structures operating at very low temperatures is disclosed. An apparatus and method for fabricating the improved blanket are also disclosed. In the improved blanket, each successive layer of insulating material is greater in length and width than the preceding layer so as to accommodate thermal contraction of the layers closest to the

J. D. Gonczy; R. C. Niemann; W. N. Boroski

1992-01-01

7

Aerogel beads as cryogenic thermal insulation system  

NASA Astrophysics Data System (ADS)

An investigation of the use of aerogel beads as thermal insulation for cryogenic applications was conducted at the Cryogenics Test Laboratory of NASA Kennedy Space Center. Steady-state liquid nitrogen boiloff methods were used to characterize the thermal performance of aerogel beads in comparison with conventional insulation products such as perlite powder and multilayer insulation (MLI). Aerogel beads produced by Cabot Corporation have a bulk density below 100 kilograms per cubic meter (kg/m3) and a mean particle diameter of 1 millimeter (mm). The apparent thermal conductivity values of the bulk material have been determined under steady-state conditions at boundary temperatures of approximately 293 and 77 kelvin (K) and at various cold vacuum pressures (CVP). Vacuum levels ranged from 10-5 torr to 760 torr. All test articles were made in a cylindrical configuration with a typical insulation thickness of 25 mm. Temperature profiles through the thickness of the test specimens were also measured. The results showed the performance of the aerogel beads was significantly better than the conventional materials in both soft-vacuum (1 to 10 torr) and no-vacuum (760 torr) ranges. Opacified aerogel beads performed better than perlite powder under high-vacuum conditions. Further studies for material optimization and system application are in progress. .

Fesmire, J. E.; Augustynowicz, S. D.; Rouanet, S.

2002-05-01

8

Aerogel insulation systems for space launch applications  

NASA Astrophysics Data System (ADS)

New developments in materials science in the areas of solution gelation processes and nanotechnology have led to the recent commercial production of aerogels. Concurrent with these advancements has been the development of new approaches to cryogenic thermal insulation systems. For example, thermal and physical characterizations of aerogel beads under cryogenic-vacuum conditions have been performed at the Cryogenics Test Laboratory of the NASA Kennedy Space Center. Aerogel-based insulation system demonstrations have also been conducted to improve performance for space launch applications. Subscale cryopumping experiments show the thermal insulating ability of these fully breathable nanoporous materials. For a properly executed thermal insulation system, these breathable aerogel systems are shown to not cryopump beyond the initial cooldown and thermal stabilization phase. New applications are being developed to augment the thermal protection systems of space launch vehicles, including the Space Shuttle External Tank. These applications include a cold-boundary temperature of 90 K with an ambient air environment in which both weather and flight aerodynamics are important considerations. Another application is a nitrogen-purged environment with a cold-boundary temperature of 20 K where both initial cooldown and launch ascent profiles must be considered. Experimental results and considerations for these flight system applications are discussed.

Fesmire, J. E.

2006-02-01

9

Aerogel insulation applications for liquid hydrogen launch vehicle tanks  

Microsoft Academic Search

Solutions to thermal insulation problems using aerogel beads were demonstrated for space launch vehicles using a model of the space shuttle external tank’s liquid hydrogen (LH2) intertank. Test results using liquid helium show that with aerogel, the nitrogen mass inside the intertank is greatly reduced and free liquid nitrogen is eliminated. Physisorption within the aerogel was also investigated, showing that

J. E. Fesmire; J. P. Sass

2008-01-01

10

Aerogel-Based Insulation for High-Temperature Industrial Processes  

Microsoft Academic Search

Under this program, Aspen Aerogels has developed an industrial insulation called Pyrogel HT, which is 4-5 times more thermally efficient than current non-aerogel technology. Derived from nanoporous silica aerogels, Pyrogel HT was specifically developed to address a high temperature capability gap not currently met with Aspen Aerogels{trademark} flagship product, Pyrogel XT. Pyrogel XT, which was originally developed on a separate

Owen Evans

2011-01-01

11

Fullerene Type Multilayer Insulation Blanket on a Spherical Cold Surface  

Microsoft Academic Search

Fullerene type multilayer insulation blanket is proposed for the insulation around a spherical cold surface, and has been applied to a 10 liter spherical tank of liquid nitrogen. As fullerene has 32 faces with 90 edges, 32 polygons of stacked insulation sheets must be connected each other to fabricate such a MLI blanket. The MLI blanket has 90 slots at

T. Ohmori; T. Shinozaki; H. Kaneko

2010-01-01

12

Performance characterization of perforated multilayer insulation blankets  

Microsoft Academic Search

Perforated multilayer insulation (MLI) blanket systems are targeted for large- scale cryogenic facilities. Space applications and particle accelerators are two fields concerned with thermal shielding of cryogenic devices. Because radiation heat transfer varies with T 4, heat transfer in the range of 300 K to 77 K is dominant even for devices operating at temperatures as low as 2 K.

13

Thermal and Solar-Optical Properties of Silica Aerogel for Use in Insulated Windows.  

National Technical Information Service (NTIS)

Silica aerogel is a porous insulating material that is transport to solar radiation. To understand its insulating performance in a window system, it is necessary to first study component heat transfer paths. Aerogel's absorption coefficient, a measure of ...

J. Hartmann M. Rubin D. Arasteh

1987-01-01

14

Aerogel-Based Insulation for High-Temperature Industrial Processes  

SciTech Connect

Under this program, Aspen Aerogels has developed an industrial insulation called Pyrogel HT, which is 4-5 times more thermally efficient than current non-aerogel technology. Derived from nanoporous silica aerogels, Pyrogel HT was specifically developed to address a high temperature capability gap not currently met with Aspen Aerogels{trademark} flagship product, Pyrogel XT. Pyrogel XT, which was originally developed on a separate DOE contract (DE-FG36-06GO16056), was primarily optimized for use in industrial steam processing systems, where application temperatures typically do not exceed 400 C. At the time, further improvements in thermal performance above 400 C could not be reasonably achieved for Pyrogel XT without significantly affecting other key material properties using the current technology. Cumulative sales of Pyrogel HT into domestic power plants should reach $125MM through 2030, eventually reaching about 10% of the total insulation market share in that space. Global energy savings would be expected to scale similarly. Over the same period, these sales would reduce domestic energy consumption by more than 65 TBtu. Upon branching out into all industrial processes in the 400 C-650 C regime, Pyrogel HT would reach annual sales levels of $150MM, with two-thirds of that being exported.

Dr. Owen Evans

2011-10-13

15

Thermal resistance and compressive strain of underwater aerogel syntactic foam hybrid insulation at atmospheric and elevated hydrostatic pressure  

NASA Astrophysics Data System (ADS)

The purpose of this study was to present a new underwater thermal insulation designed for flexibility and high thermal resistance. The insulation was a hybrid composite of two constituents: syntactic foam and an insulating aerogel blanket. Methods for treating and combining the constituents into a hybrid insulation of several designs are presented. A final configuration was selected based on high thermal resistance and was tested for thermal resistance and compressive strain to a pressure of 1.2 MPa (107 msw, meters of sea water) for five continuous pressure cycles. The thermal resistance and compressive strain results were compared to foam neoprene and underwater pipeline insulation. It was found that the hybrid insulation has a thermal resistance significantly higher than both foam neoprene and underwater pipeline insulation at atmospheric and elevated hydrostatic pressures (1.2 MPa). The total thermal resistance of the hybrid insulation decreased 32% at 1.2 MPa and returned to its initial value upon decompression. It was concluded that the hybrid insulation, with modifications, could be used for wetsuit construction, shallow underwater pipeline insulation, or any underwater application where high thermal resistance, flexibility, and resistance to compression are desired.

Bardy, Erik; Mollendorf, Joseph; Pendergast, David

2006-05-01

16

Heat insulation performance, mechanics and hydrophobic modification of cellulose-SiO2 composite aerogels.  

PubMed

Cellulose-SiO2 composite hydrogel was prepared by combining the NaOH/thiourea/H2O solvent system and the immersion method with controlling the hydrolysis-fasculation rate of tetraethyl orthosilicate (TEOS). The hydrophobic composite aerogels were obtained through the freeze-drying technology and the cold plasma modification technology. Composite SiO2 could obviously reduce the thermal conductivity of cellulose aerogel. The thermal conductivity could be as low as 0.026 W/(mK). The thermal insulation mechanism of the aerogel material was discussed. Composite SiO2 reduced hydrophilicity of cellulose aerogel, but environmental humidity had a significant influence on heat insulation performance. After hydrophobic modification using CCl4 as plasma was conducted, the surface of composite aerogel was changed from hydrophilic to hydrophobic and water contact angle was as high as 132°. The modified composite aerogel still kept good heat insulation performance. This work provided a foundation for the possibility of applying cellulose-SiO2 composite aerogel in the insulating material field. PMID:23987346

Shi, Jianjun; Lu, Lingbin; Guo, Wantao; Zhang, Jingying; Cao, Yang

2013-06-19

17

A blanket design, apparatus, and fabrication techniques for the mass production of multilayer insulation blankets for the Superconducting Super Collider  

Microsoft Academic Search

The multilayer insulation (MLI) system for the Superconducting Super Collider (SSC) consists of full cryostat length assemblies of aluminized polyester film fabricated in the form of blankets and installed as blankets to the 4.5K cold mass and the 20K and 80K thermal radiation shields. Approximately 40,000 MLI blankets will be required in the 10,000 cryogenic devices comprising the SSC accelerator.

J. D. Gonczy; W. N. Boroski; R. C. Niemann; J. G. Otavka; M. K. Ruschman; C. J. Schoo

1989-01-01

18

A blanket design, apparatus, and fabrication techniques for the mass production of multilayer insulation blankets for the Superconducting Super Collider  

SciTech Connect

The multilayer insulation (MLI) system for the Superconducting Super Collider (SSC) consists of full cryostat length assemblies of aluminized polyester film fabricated in the form of blankets and installed as blankets to the 4.5K cold mass and the 20K and 80K thermal radiation shields. Approximately 40,000 MLI blankets will be required in the 10,000 cryogenic devices comprising the SSC accelerator. Each blanket is nearly 17 meters long and 1.8 meters wide. This paper reports the blanket design, an apparatus, and the fabrication method used to mass produce pre-fabricated MLI blankets. Incorporated in the blanket design are techniques which automate quality control during installation of the MLI blankets in the SSC cryostat. The apparatus and blanket fabrication method insure consistency in the mass produced blankets by providing positive control of the dimensional parameters which contribute to the thermal performance of the MLI blanket. By virtue of the fabrication process, the MLI blankets have inherent features of dimensional stability three-dimensional uniformity, controlled layer density, layer-to-layer registration, interlayer cleanliness, and interlayer material to accommodate thermal contraction differences. 11 refs., 6 figs., 1 tab.

Gonczy, J.D.; Boroski, W.N.; Niemann, R.C.; Otavka, J.G.; Ruschman, M.K.; Schoo, C.J.

1989-09-01

19

Blanket Design, Apparatus, and Fabrication Techniques for the Mass Production of Multilayer Insulation Blankets for the Superconducting Super Collider.  

National Technical Information Service (NTIS)

The multilayer insulation (MLI) system for the Superconducting Super Collider (SSC) consists of full cryostat length assemblies of aluminized polyester film fabricated in the form of blankets and installed as blankets to the 4.5K cold mass and the 20K and...

J. D. Gonczy W. N. Boroski R. C. Niemann J. G. Otavka M. K. Ruschman

1989-01-01

20

Polyurea based aerogel for a high performance thermal insulation material  

Microsoft Academic Search

Less fragile lightweight nanostructured polyurea based organic aerogels were prepared via a simple sol–gel processing and\\u000a supercritical drying method. The uniform polyurea wet gels were first prepared at room temperature and atmospheric pressure\\u000a by reacting different isocyanates with polyamines using a tertiary amine (triethylamine) catalyst. Gelation kinetics, uniformity\\u000a of wet gel, and properties of aerogel products were significantly affected by

Je Kyun Lee; George L. Gould; Wendell Rhine

2009-01-01

21

Thermo-hygric properties of a newly developed aerogel based insulation rendering for both exterior and interior applications  

Microsoft Academic Search

A new kind of rendering based on silica aerogel granulates was developed showing a high performance namely a low thermal conductivity and a low vapour transmission resistance, a combination of characteristics unachieved by existing renderings. This insulation rendering has a clear advantage over insulation boards which need a plane subsurface, adjustment, gluing and even fastening by means of dowels. A

Th. Stahl; S. Brunner; M. Zimmermann; K. Ghazi Wakili

22

Effects of weave architecture on aeroacoustic performance of ceramic insulation blankets  

SciTech Connect

A comparison of sewn, quilted Advanced Flexible Reusable Surface Insulation (AFRSI) blankets and integrally woven core Tailorable Advanced Blanket Insulation (TABI) systems was conducted in a 170 decibel aeroacoustic environment under oscillating air loads. Preconditioning in a radiant heat source was done at both 2,000[degrees]F and 2,500[degrees]F before testing. It was shown that a multilayer weave construction based on an angle interlock weave architecture was superior to other systems investigated and did not require a surface coating to enhance survivability. Single-ply TABI fabric surfaces using an insulated intergrally woven core structure can survive up to 2,000[degrees]F without the use of a ceramic coating to toughen the surface to the aeroacoustic noise level. AFRSI blankets required a ceramic coating in order to demonstrate comparable performance after exposure to a 2,000[degrees]F radiant heat temperature. 14 refs., 7 figs., 2 tabs.

Sawko, P.M. (NASA Ames Research Center, Moffet Field, CA (United States)); Tran, D. (San Jose State Univ., CA (United States))

1993-10-01

23

Cryogenic Thermal Performance Testing of Bulk-Fill and Aerogel Insulation Materials  

NASA Astrophysics Data System (ADS)

Thermal conductivity testing under actual-use conditions is a key to understanding how cryogenic thermal insulation systems perform in regard to engineering, economics, and materials factors. The Cryogenics Test Laboratory at NASA's Kennedy Space Center tested a number of bulk-fill insulation materials, including aerogel beads, glass bubbles, and perlite powder, using a new cylindrical cryostat. Boundary temperatures for the liquid nitrogen boiloff method were 78 K and 293 K. Tests were performed as a function of cold vacuum pressure under conditions ranging from high vacuum to no vacuum. Results were compared with those from complementary test methods in the range of 20 K to 300 K. Various testing techniques are required to completely understand the operating performance of a material and to provide data for answers to design engineering questions.

Scholtens, B. E.; Fesmire, J. E.; Sass, J. P.; Augustynowicz, S. D.; Heckle, K. W.

2008-03-01

24

Electrically insulating coatings for V-Li self-cooled blanket in a fusion system  

SciTech Connect

The blanket system is one of the most important components in a fusion reactor because it has a major impact on both the economics and safety of fusion energy. The primary functions of the blanket in a deuterium/tritium-fueled fusion reactor are to convert the fusion energy into sensible heat and to breed tritium for the fuel cycle. The liquid-metal blanket concept requires an electrically insulating coating on the first-wall structural material to minimize the magnetohydrodynamic pressure drop that occurs during the flow of liquid metal in a magnetic field. Based on the thermodynamics of interactions between the coating and the liquid lithium on one side and the structural V-base alloy on the other side, several coating candidates are being examined to perform the insulating function over a wide range of temperatures and lithium chemistries.

Natesan, K.; Reed, C. B.; Uz, M.; Park, J. H.; Smith, D. L.

2000-05-17

25

A Thermal Resistance (R-Value) Correlation for Blow-in-Blanket Mineral Fiber Insulation  

Microsoft Academic Search

A correlation between the apparent thermal conductivity, measured at 75°F, and density of mineral fiber insulation has been developed for the fiber most commonly used in Blow-in-Blanket (BIB) applications. The correlation describes the data obtained for specimens prepared by six contractors to within ±5% in the den sity range 1.6 to 3.0 1b\\/ft3. R-value per inch increased from 3.85 ft2.hr.°F\\/Btu.in

David W. Yarbrough; Clay C. Bare

1992-01-01

26

Applications for silica aerogel products  

Microsoft Academic Search

Aerogels, nanoporous lightweight materials, were discovered more than 60 years ago. The supercritical manufacturing process and expensive raw materials typically used to produce aerogels prohibited commercialization on an industrial scale. Recently, a commercially attractive ambient pressure production process was developed which will allow broader commercialization of silica aerogel products. Some aerogel products for insulation applications and their preparation is described.

M. Schmidt; F Schwertfeger

1998-01-01

27

Hydrophobic and thermal insulation properties of silica aerogel\\/epoxy composite  

Microsoft Academic Search

Silica aerogel\\/epoxy composite was prepared by dry mixing hydrophobic aerogels with epoxy powders and heat pressing method. The composite materials show a serviceability temperature up to 250°C with low thermal conductivity (0.11–0.044W\\/mk) and hydrophobic property (water contact angle of 117–140°). Transmission electron microscope photos proved that part of silica aerogels nanopores had been immersed by epoxy. Based on this phenomenon,

Dengteng Ge; Lili Yang; Yao Li; Jiupeng Zhao

2009-01-01

28

Technical applications of aerogels  

SciTech Connect

Aerogel materials posses such a wide variety of exceptional properties that a striking number of applications have developed for them. Many of the commercial applications of aerogels such as catalysts, thermal insulation, windows, and particle detectors are still under development and new application as have been publicized since the ISA4 Conference in 1994: e.g.; supercapacitors, insulation for heat storage in automobiles, electrodes for capacitive deionization, etc. More applications are evolving as the scientific and engineering community becomes familiar with the unusual and exceptional physical properties of aerogels, there are also scientific and technical application, as well. This paper discusses a variety of applications under development at Lawrence Livermore National Laboratory for which several types of aerogels are formed in custom sizes and shapes. Particular discussions will focus on the uses of aerogels for physics experiments which rely on the exceptional, sometimes unique, properties of aerogels.

Hrubesh, L.W.

1997-08-18

29

Mechanism of low thermal conductivity of xonotlite-silica aerogel nanoporous super insulation material  

Microsoft Academic Search

In an effort to incorporate the low thermal conductivity of the silica aerogel and the superior structure strength of the xonotlite, a composite material of these two was produced. It was synthesized under vacuum condition and dried by supercritical drying technique. The thermal conductivity of the new material, which is at 298 K with the gas pressure ranging from 1.01×105

Hailong Yang; Wen Ni; Deping Chen; Guoqiang Xu; Tao Liang; Li Xu

2008-01-01

30

Sol-gel zirconia coatings aimed at dust suppression in aluminosilicate high temperature insulating blankets  

Microsoft Academic Search

The feasibility of reducing the amount of loftable fibres in aluminosilicate blankets by coating with sol-gel zirconia was studied. A zirconium alkoxide based solution was employed to coat small samples of blanket using a dip-coating technique. The zirconia coatings and two grades of blanket were analysed using DTA, XRD, SEM and optical microscopy techniques to characterize any reactions and phase

B. Ben-Nissan; D. Martin

1996-01-01

31

Mechanical Properties of Aerogels.  

National Technical Information Service (NTIS)

Aerogels are extremely low density solids that are characterized by a high porosity and pore sizes on the order of nanometers. Their low thermal conductivity and sometimes transparent appearance make them desirable for applications such as insulation in c...

K. E. Parmenter F. Milstein

1995-01-01

32

Aerogel: Tile Composites Toughen a Brittle Superinsulation.  

National Technical Information Service (NTIS)

Pure aerogels, though familiar in the laboratory for decades as exotic lightweight insulators with unusual physical properties, have had limited industrial applications due to their low strength and high brittleness. Composites formed of aerogels and the ...

S. White D. Rasky

1998-01-01

33

Mechanical Properties of Aerogels. Final Report  

Microsoft Academic Search

Aerogels are extremely low density solids that are characterized by a high porosity and pore sizes on the order of nanometers. Their low thermal conductivity and sometimes transparent appearance make them desirable for applications such as insulation in cryogenic vessels and between double paned glass in solar architecture. An understanding of the mechanical properties of aerogels is necessary before aerogels

K. E. Parmenter; F. Milstein

1995-01-01

34

Monolithic silica aerogel in superinsulating glazings  

Microsoft Academic Search

Silica aerogel is an open-pored porous transparent material with optical and thermal properties that makes the material very interesting as an insulation material in windows. A number of different aerogels have been investigated for their optical and thermal performance. High thermal resistance of aerogel was found for all the investigated samples and the samples showed very high solar as well

K Duer; S Svendsen

1998-01-01

35

Beta cloth durability assessment for Space Station Freedom (SSF) Multi-Layer Insulation (MLI) blanket covers  

Microsoft Academic Search

MLI blankets for the Space Station Freedom (SSF) must comply with general program requirements and recommendations for long life and durability in the low-Earth orbit (LEO) environment. Atomic oxygen and solar ultraviolet\\/vacuum ultraviolet are the most important factors in the SSF natural environment which affect materials life. Two types of Beta cloth (Teflon coated woven glass fabric), which had been

S. L. Koontz; S. Jacobs; J. Le

1993-01-01

36

System and Method for Suppressing Sublimation using Opacified Aerogel.  

National Technical Information Service (NTIS)

The present invention relates to a castable, aerogel-based, ultra-low thermal conductivity opacified insulation to suppress sublimation. More specifically, the present invention relates to an aerogel opacified with various opacifying or reflecting constit...

J. A. Palk J. G. Snyder J. P. Fleurial J. S. Sakamoto S. M. Jones T. Calliat

2004-01-01

37

Transparent and crack-free silica aerogels  

NASA Astrophysics Data System (ADS)

The process of making silica aerogels has been studied in detail over the past two decades due to its usage in a wide range of low end applications such as thermal insulators, super-capacitors etc., as well as high end applications like particle physics, space explorations. These applications call for control over the properties of aerogels, such as their transparency, density, porosity, pore size, and integrity. However, despite all the past research, controlling properties of aerogels is still not a fully developed science, a lot more research needs to be done. The literature on silica aerogels does not cover the study of the relation between transparency and cracks in aerogels -- which can be a key factor in making aerogels for many applications. Hence, optimization of the transparency and integrity of the aerogels in order to obtain high transparency and low cracks was attempted in this thesis.

Athmuri, Kalyan Ram

38

Radiation transport and image transmission through aerogels  

Microsoft Academic Search

Optical and thermal properties of aerogels play an important role in their application as transparent insulation, daylighting systems and superinsulated windows. Directional-directional transmission, tdd, as well as the directional-hemispherical transmission, tdh, are presented for 20 mm thick monolithic and granular SiO2 aerogel. For optimized monolithic aerogels, averaged transmission values of t?dh,sol = (91 ± 14)% and t?dd,vis = (84 ±

A. Beck; J Linsmeier; W Körner; H Scheller; J Fricke

1995-01-01

39

Influence of Boehmite Precursor on Aluminosilicate Aerogel Pore Structure, Phase Stability and Resistance to Densification at High Temperatures.  

National Technical Information Service (NTIS)

Aluminosilicate aerogels are of interest as constituents of thermal insulation systems for use at temperatures higher than those attainable with silica aerogels. It is anticipated that their effectiveness as thermal insulators will be influenced by their ...

F. I. Hurwitz H. Guo K. N. Newlin

2011-01-01

40

Design Tool for Cryogenic Thermal Insulation Systems  

SciTech Connect

Thermal isolation of low-temperature systems from ambient environments is a constant issue faced by practitioners of cryogenics. For energy-efficient systems and processes to be realized, thermal insulation must be considered as an integrated system, not merely an add-on element. A design tool to determine the performance of insulation systems for comparative trade-off studies of different available material options was developed. The approach is to apply thermal analysis to standard shapes (plane walls, cylinders, spheres) that are relatively simple to characterize with a one-dimensional analytical or numerical model. The user describes the system hot and cold boundary geometry and the operating environment. Basic outputs such as heat load and temperature profiles are determined. The user can select from a built-in insulation material database or input user defined materials. Existing information has been combined with the new experimental thermal conductivity data produced by the Cryogenics Test Laboratory for cryogenic and vacuum environments, including high vacuum, soft vacuum, and no vacuum. Materials in the design tool include multilayer insulation, aerogel blankets, aerogel bulk-fill, foams, powders, composites, and other insulation system constructions. A comparison of the design tool to a specific composite thermal insulation system is given.

Demko, Jonathan A [ORNL; Fesmire, J. E. [NASA Kennedy Space Center, Kennedy Space Center, Florida; Augustynowicz, S. D. [Sierra Lobo Inc., Kennedy Space Center, Florida

2008-01-01

41

Polyurea Aerogels.  

National Technical Information Service (NTIS)

Polyurea aerogels as well as methods for preparing the same are disclosed. One method involves mixing a polyisocyanate with a polyamine in a solvent and supercritically drying the resultant gel. Polyoxyalkyleneamine are a preferred type of the polyamines....

J. K. Lee

2006-01-01

42

Vinduer og solvaegge med monolitisk silica aerogel. (Windows and solar walls with monolithic solica aerogel).  

National Technical Information Service (NTIS)

This report deals with the experimental and theoretical work concerning application of evacuated monolithic silica aerogel as a transparent insulating material for window panes and covers for solar walls. Models for determination of the heat transfer thro...

K. Ingerslev Jensen

1991-01-01

43

Synthesis and physico-chemical properties of organic aerogels  

NASA Astrophysics Data System (ADS)

Basically, an organic aerogel is any aerogel with a framework consists of organic polymers. The organic aerogels are fabricated by the sol-gel polymerization of resorcinol with formaldehyde, followed by exchanging with acetone, and then with liquid CO2 and drying under CO2 supercritical conditions. The organic aerogels obtained by this process exhibits themselves as an insulators i.e. they possesses high resistance to the flow of current through them. These obtained aerogels when heated at elevated temperatures of about 1100 °C they becomes conducting, demonstrates themselves a low resistance of the order of 4?.

Kavale, Mahendra S.; Parale, V. G.; Rao, A. Venkateswara; Wagh, P. B.; Gupta, Satish C.

2013-06-01

44

Aerogel commercialization pilot project. Final program report  

SciTech Connect

Aerogels are extremely light weight, high surface area, very insulative materials that offer many potential improvements to commercial products. Aerogels have been the subject of extensive research at Department of Energy Laboratories and have been considered one of the technology most ready for commercialization. However, commercialization of the technology had been difficult for the National Laboratories since end users were not interested in the high temperature and high pressure chemical processes involved in manufacturing the raw material. Whereas, Aerojet as a supplier of rocket fuels, specialty chemicals and materials had the manufacturing facilities and experience to commercially produce aerogel-type products. Hence the TRP provided a link between the technology source (National Laboratories), the manufacturing (Aerojet) and the potential end users (other TRP partners). The program successfully produced approximately 500 ft{sup 2} of organic aerogel but failed to make significant quantities of silica aerogel. It is significant that this production represents both the largest volume and biggest pieces of organic aerogel ever produced. Aerogels, available from this program, when tested in several prototype commercial products were expected to improve the products performance, but higher than expected projected production costs for large scale manufacture of aerogels has limited continued commercial interest from these partners. Aerogels do, however, offer potential as a specialty material for some high value technology and defense products.

NONE

1996-02-13

45

Aerogel commercialization: Technology, markets and costs  

SciTech Connect

Commercialization of aerogels has been slow due to several factors including cost and manufacturability issues. The technology itself is well enough developed as a result of work over the past decade by an international-community of researchers. Several extensive substantial markets appear to exist for aerogels as thermal and sound insulators, if production costs can keep prices in line with competing established materials. The authors discuss here the elements which they have identified as key cost drivers, and they give a prognosis for the evolution of the technology leading to reduced cost aerogel production.

Carlson, G.; Lewis, D.; McKinley, K.; Richardson, J.; Tillotson, T.

1994-10-07

46

Shrinkage and pore structure in preparation of carbon aerogels  

Microsoft Academic Search

To aim at thermal insulator applications, the shrinkage and the pore structure of resorcinol–formaldehyde (RF) aerogels and\\u000a carbon aerogels were investigated during the supercritical drying and the carbonization process. The water (W) molar ratio\\u000a has small effects on the surface area or the particle size, but has significant effects on the density of the aerogel. Higher\\u000a W\\/R ratio leads to

Junzong FengJian; Jian Feng; Changrui Zhang

47

Evacuated aerogel glazings  

Microsoft Academic Search

This paper describes the main characteristics of monolithic silica aerogel and its application in evacuated superinsulating aerogel glazing including the evacuation and assembling process. Furthermore, the energetic benefit of aerogel glazing is quantified. In evacuated aerogel glazing the space between the glass panes is filled with monolithic silica aerogel evacuated to a rough vacuum of approximately 1–10hPa. The aerogel glazing

J. M. Schultz; K. I. Jensen

2008-01-01

48

Silica aerogel-polymer nanocomposites and new nanoparticle syntheses  

Microsoft Academic Search

Aerogels are extremely high surface area, low density materials with applications including thermal and acoustic insulators, radiation detectors and cometary dust particle traps. However, their low density and aggregate structure makes them extremely fragile and practically impossible to machine or handle without breaking. This has led to the development of aerogel composites with enhanced mechanical properties through the addition of

Dylan Joseph Boday

2009-01-01

49

Tailoring mechanical properties of aerogels for aerospace applications.  

PubMed

Silica aerogels are highly porous solid materials consisting of three-dimensional networks of silica particles and are typically obtained by removing the liquid in silica gels under supercritical conditions. Several unique attributes such as extremely low thermal conductivity and low density make silica aerogels excellent candidates in the quest for thermal insulation materials used in space missions. However, native silica aerogels are fragile at relatively low stresses. More durable aerogels with higher strength and stiffness are obtained by proper selection of silane precursors and by reinforcement with polymers. This paper first presents a brief review of the literature on methods of silica aerogel reinforcement and then discusses our recent activities in improving not only the strength but also the elastic response of polymer-reinforced silica aerogels. Several alkyl-linked bis-silanes were used in promoting flexibility of the silica networks in conjunction with polymer reinforcement by epoxy. PMID:21361281

Randall, Jason P; Meador, Mary Ann B; Jana, Sadhan C

2011-03-01

50

Experimental investigation on mechanical properties of a fiber-reinforced silica aerogel composite  

Microsoft Academic Search

Aerogel has been used for thermal insulation because of its extremely low thermal conductivity, but the application has been restricted to non-loading-bearing structures by its low strength properties. Fiber-reinforced aerogel was prepared with higher strength but without sacrificing much of its thermal conductivity. While fiber-reinforced aerogel performs as load-bearing insulation, two behaviors must be investigated: compression and stress relaxation at

Xiaoguang Yang; Yantao Sun; Duoqi Shi; Jinlong Liu

2011-01-01

51

Multilayer insulation for spacecraft applications  

Microsoft Academic Search

Multilayer Insulation (MLI) blankets provide a lightweight insulation system with a high thermal resistance in vacuum. MLI blankets are utilized to reduce heat loss from a spacecraft to the cold space, or to prevent excessive heating of the surroundings from an internal component with heat dissipation. MLI blankets consist of a number of highly reflecting radiation shields interspaced with a

Che-Shing Kang

1999-01-01

52

Electrical Insulators for the Theta-Pinch Fusion Reactor.  

National Technical Information Service (NTIS)

The five major applications for electrical insulators in the Reference Theta Pinch Reactor are as follows: (1) first-wall insulator, (2) blanket intersegment insulator, (3) graphite encapsulating insulator, (4) implosion coil insulator, and (5) compressio...

F. W. Clinard

1976-01-01

53

Resorcinol-formaldehyde and carbon aerogel microspheres  

SciTech Connect

Aerogels are a unique class of materials possessing an open-cell structure with ultrafine cells/pores (<100nm), high surface area (400--1100 m{sup 2}/g), and a solid matrix composed of interconnected particles, fibers, or platelets with characteristic dimensions of 10nm. Although monolithic aerogels are ideal candidates for many applications (e.g. transparent window insulation), current processing methods have limited their introduction into the commercial marketplace. Our research focuses on the formation of resorcinol-formaldehyde (RF) aerogel microspheres which offer an attractive alternative to monolith production. An inverse emulsion polymerization is used to produce these spherical gel particles which undergo solvent exchange followed by supercritical drying with carbon dioxide. This process yields aerogel microspheres (10--80{mu} diameter) which can be used as loosely packed powders, compression molded into near-net shapes using a polymer binder, or used as additives in conventional foaming operations to produce new aerogel composites with superior thermal properties. The emulsification procedure, thermal characterization, mechanical properties, and potential applications of RF aerogel microspheres will be discussed.

Alviso, C.T.; Pekela, R.W.; Gross, J. [Lawrence Livermore National Lab., CA (United States); Lu, X.; Caps, R.; Fricke, J [Wuerzburg Univ. (Germany). Physikalisches Inst.

1996-04-01

54

Thin aerogel films for optical, thermal, acoustic, and electronic applications  

SciTech Connect

Aerogels are a special class of continuously porous solid materials which are characterized by nanometer size particles and pores. Typically, aerogels are made using sol-gel chemistry to form a solvent filled, high porosity gel that is dried by removing the solvent without collapsing the tenuous solid phase. As bulk materials, aerogels are known to have many exceptional, and even some unique physical properties. Aerogels provide the highest thermal insulation and lowest dielectric constant of any other material known. However, some important applications require the aerogels in the form of thin films or sheets. For example, electronic applications require micrometer thin aerogel films bonded to a substrate, and others require thicker films, either on a substrate or as free standing sheets. Special methods are required to make aerogel thin films or sheets. In this paper, the authors discuss the special conditions needed to fabricate thin aerogel films and they describe methods to make films and thin sheets. They also give some specific applications for which aerogel films are being developed.

Hrubesh, L.W.; Poco, J.F. [Lawrence Livermore National Lab., CA (United States). Chemistry and Material Sciences Dept.

1994-09-01

55

Melamine-formaldehyde aerogels.  

National Technical Information Service (NTIS)

The ability to tailor the structure and properties of aerogels at the nanometer scale opens up exciting possibilities for these unique, low density materials. Traditional inorganic aerogels have been formed from the hydrolysis and condensation of metal al...

C. T. Alviso R. W. Pekala

1991-01-01

56

Highly Insulating Windows with a U-value less than 0.6 W/m2K  

SciTech Connect

U.S. households rely primarily on three sources of energy: natural gas, electricity, and fuel oil. In the past several decades, electricity consumption by households has grown dramatically, and a significant portion of electricity used in homes is for lighting. Lighting includes both indoor and outdoor lighting and is found in virtually every household in the United States. In 2001, according to the US Energy Information Administration, lighting accounted for 101 billion kWh (8.8 percent) of U.S. household electricity use. Incandescent lamps, which are commonly found in households, are highly inefficient sources of light because about 90 percent of the energy used is lost as heat. For that reason, lighting has been one focus area to increase the efficiency of household electricity consumption. Windows have several functions, and one of the main functions is to provide a view to the outside. Daylighting is another one of windows main functions and determines the distribution of daylight to a space. Daylighting windows do not need to be transparent, and a translucent daylighting window is sufficient, and often desired, to diffuse the light and make the space more environmentally pleasing. In homes, skylights are one source of daylighting, but skylights are not very energy efficient and are inseparably linked to solar heat gain. In some climates, added solar heat gains from daylighting may be welcome; but in other climates, heat gain must be controlled. More energy efficient skylights and daylighting solutions, in general, are desired and can be designed by insulating them with aerogels. Aerogels are a highly insulating and transparent material in its pure form. The overall objective for this project was to prepare an economical, translucent, fiber-reinforced aerogel insulation material for daylighting applications that is durable for manufacturing purposes. This advanced insulation material will increase the thermal performance of daylighting windows, while satisfying constraints such as durability, cost, user acceptance, size limits, and environmental safety concerns. The energy efficient daylighting window will consist of a translucent and resilient aerogel panel sandwiched between glass panes in double glazed windows. Compared to the best windows available today, the double glazed translucent windows with 1/2-inch aerogel inserts will have a U-value of 1.2 W/m{sup 2} K (0.211 BTU/ft{sup 2} h F) without any coating or low conductivity fill gases. These windows will be more effective than the windows with an Energy Star rating of U-2 W/m{sup 2} K and could be made even more efficient by using low-e coated glass glazings and inert gas fills. This report summarizes the work accomplished on Cooperative Agreement DE-FC26-03NT41950. During this project, Aspen Aerogels made transparent and translucent aerogels from TMOS and TEOS. We characterized the transparency of the aerogels, reinforced the transparent aerogels with fibers and prepared large translucent aerogel panels and blankets. We also conducted an initial market study for energy efficient translucent windows. A lab-scale process was developed that could be scaled-up to manufacture blankets of these translucent aerogels. The large blankets prepared were used to fabricate prototype translucent windows and skylights. The primary goal of this project was to develop transparent, resilient, hydrophobic silica aerogels that have low thermal conductivities (R-10/inch) to be used to produce aerogel insulated double-glazing windows with a U value of 0.6 W/m{sup 2}K. To meet this objective we developed a process and equipment to produce blankets of translucent, hydrophobic aerogel. We focused on silica, organically-modified silica aerogels (Ormosils), and fiber reinforced silica aerogels due to the appreciable expertise in silica sol-gel processing available with the personnel at Aspen Aerogels, and also due to the quantity of knowledge available in the scientific literature. The project was conducted in three budget periods, herein called BP1, BP2 and BP3.

Wendell Rhine; Ying Tang; Wenting Dong; Roxana Trifu; Reduane Begag

2008-11-30

57

Blanket technology experiments at Argonne National Laboratory  

NASA Astrophysics Data System (ADS)

Argonne National Laboratory has the largest U.S. program for the development of blanket technology. The goals of the program are to resolve critical issues for different blanket concepts, to develop the understanding and predictive capability of blanket behavior, and to develop the technology needed to build and operate advanced fusion blankets. The projects within the program are liquid metal MHD, breeder neutronics, tritium oxidation, transient electromagnetics, FLIBE chemistry, and insulator coatings. The present status and recent results of the projects are described.

Mattas, R. F.; Reed, C. B.; Picologlou, B.; Finn, P.; Clemmer, R.; Porges, K.; Bennett, E.; Turner, L. R.

1988-02-01

58

Method of casting aerogels  

DOEpatents

The invention describes a method for making monolithic castings of transparent silica aerogel with densities in the range from 0.001 g/cm[sup 3] to 0.6 g/cm[sup 3]. Various shapes of aerogels are cast in flexible polymer molds which facilitate removal and eliminate irregular surfaces. Mold dimensions are preselected to account for shrinkage of aerogel which occurs during the drying step of supercritical extraction of solvent. 2 figures.

Poco, J.F.

1993-09-07

59

Melamine-formaldehyde aerogels  

DOEpatents

Organic aerogels that are transparent and essentially colorless are prepared from the aqueous, sol-gel polymerization of melamine with formaldehyde. The melamine-formaldehyde (MF) aerogels have low densities, high surface areas, continuous porosity, ultrafine cell/pore sizes, and optical clarity. 3 figs.

Pekala, R.W.

1992-01-14

60

Chitin Nanowhisker Aerogels  

PubMed Central

Chitin nanowhiskers are structured into mesoporous aerogels by using the same benign process used previously in our group to make cellulose nanowhisker aerogels. The nanowhiskers are sonicated in water to form a hydrogel before solvent-exchange with ethanol and drying under supercritical CO2 (scCO2). Aerogels are prepared with various densities and porosities, relating directly to the initial chitin nanowhisker content. scCO2 drying enables the mesoporous network structure to be retained as well as allowing the gel to retain its initial dimensions. The chitin aerogels have low densities (0.043–0.113 g cm?3), high porosities (up to 97 %), surface areas of up to 261 m2 g?1, and mechanical properties at the high end of other reported values (modulus between 7 and 9.3 MPa). The aerogels were further characterized by using X-ray diffraction, BET analysis, electron microscopy, FTIR, and thermogravimetric analysis. Characterization showed that the rod-like crystalline nature of the nanowhiskers was retained during the aerogel production process, making the aerogel truly an assembled structure of chitin nanocrystals. These aerogels also showed the lowest reported shrinkage during drying to date, with an average shrinkage of only 4 %.

Heath, Lindy; Zhu, Lifan; Thielemans, Wim

2013-01-01

61

Edge-to-edge assembled graphene oxide aerogels with outstanding mechanical performance and superhigh chemical activity.  

PubMed

Aerogels, an extremely important aggregation state of various self-assembled nanoscale building blocks, have great potential in fields ranging from energy storage to thermal insulation. However, the porosity of aerogels makes them mechanically weak in most cases, and the chemical activity of the resulting aerogel needs consideration. Herein, chemically crosslinked graphene oxide (GO) 3D aerogels with large specific surface areas (up to 850 m(2) g(-1) ), outstanding mechanical performance (up to 20 MPa Young's modulus, 1 MPa yield strength and 45 J g(-1) specific energy adsorption), and superhigh chemical activity (toward some reducing gases such as H2 S, HI, and SO2 ), are fabricated by assembling 2D GO sheets edge-to-edge into uniform, 3D hydrogel networks with subsequent supercritical fluid drying. These aerogels are superior to other 3D frameworks (e.g. graphene aerogels) assembled via partial overlapping of the basal planes of the 2D building blocks. PMID:23512583

Huang, Huan; Chen, Pengwan; Zhang, Xuetong; Lu, Yun; Zhan, Wanchu

2013-03-20

62

Silica aerogel-polymer nanocomposites and new nanoparticle syntheses  

NASA Astrophysics Data System (ADS)

Aerogels are extremely high surface area, low density materials with applications including thermal and acoustic insulators, radiation detectors and cometary dust particle traps. However, their low density and aggregate structure makes them extremely fragile and practically impossible to machine or handle without breaking. This has led to the development of aerogel composites with enhanced mechanical properties through the addition of polymers or surface modifiers. To date, attempts to strengthen aerogels have come with significant increases in density and processing time. Here I will describe our search for a solution to these problems with our invention using methyl cyanoacrylate chemical vapor deposition (CVD) to strengthen silica, aminated silica and bridged polysilsesquioxane aerogels. This approach led to a strength improvement of the composites within hours and the strongest composite prepared had a 100x strength improvement over the precursor aerogel. We also developed the first approach to control the molecular weight of the polymers that reinforce silica aerogels using surface-initiated atom transfer radical polymerization (SI-ATRP). Although PMMA reinforcement of silica aerogels improved the mechanical properties, further strength improvements were achieved by cross-linking the grafted PMMA. Additionally, we developed the first silica aerogels reinforced with polyaniline nanofibers that were strong and electrically conductive. Reinforcing silica aerogels with polyaniline allowed them to be used as a sensor for the detection of protonating and deprotonating gaseous species. Finally we developed a new approach for the synthesis of silica and bridged polysilsesquioxane spheres using a surfactant free synthesis. This approach allowed for the first in-situ incorporation of base sensitive functionalities during the sol-gel polymerization.

Boday, Dylan Joseph

63

Thermal alteration of hydrated minerals during hypervelocity capture to silica aerogel at the flyby speed of Stardust  

Microsoft Academic Search

Outside the Earth's atmosphere, silica aerogel is one of the best materials to capture finegrained extraterrestrial particles in impacts at hypervelocities. Because silica aerogel is a superior insulator, captured grains are inevitably influenced by frictional heat. Therefore, we performed laboratory simulations of hypervelocity capture by using light-gas guns to impact into aerogels fine-grained powders of serpentine, cronstedtite, and Murchison CM2

Takaaki Noguchi; Tomoki Nakamura; Kyoko Okudaira; Hajime Yano; Seiji Sugita; Mark J. Burchell

2007-01-01

64

Silica modified cellulosic aerogels  

Microsoft Academic Search

\\u000a Abstract  Shaped cellulosic aerogels—as the ‘young’ generation succeeding the well-established silica and synthetic polymer-based aerogels—are\\u000a intriguing materials that feature properties similar to those of their antecessors combined with the additional advantages\\u000a and characteristics of the re-growing biopolymer cellulose. Reinforced shaped cellulosic aerogels consisting of two interpenetrating\\u000a networks of cellulose and silica were prepared from shaped cellulose solutions by (1) regenerating (reprecipitating)

Marco Litschauer; Marie-Alexandra Neouze; Emmerich Haimer; Ute Henniges; Antje Potthast; Thomas Rosenau; Falk Liebner

2011-01-01

65

Optofluidic microchannels in aerogel.  

PubMed

We report optofluidic waveguides made by filling microchannels in aerogel with water. The aerogel cladding is a nanoporous material with an extremely low refractive index of ~1.05, giving a large index step from the water core. Channels were formed by removing embedded optical fibers, which could be nonuniform or multiple. The porosity of the aerogel allowed air to be displaced from the channel, preventing the trapping of bubbles. The attenuation of red light in the highly multimode water core waveguide was no greater than 1.5 dB/cm. PMID:21847232

Xiao, Limin; Birks, T A

2011-08-15

66

Photoconductivity of carbon aerogels  

Microsoft Academic Search

Photoconductivity was measured on a series of carbon aerogels to investigate their electronic properties. Carbon aerogels are a special class of low-density microcellular foams, consisting of interconnected carbon particles ([similar to]120 A diameter) and narrow graphitic ribbons ([similar to]25 A width) intertwined within each particle. Both the dark- and photo-conductivities show drastic changes in the temperature range 5--300 K, which

M. Hosoya; G. Reynolds; M. S. Dresselhaus; P. W. Pekala

1993-01-01

67

Polyimide aerogels cross-linked through amine functionalized polyoligomeric silsesquioxane.  

PubMed

We report the first synthesis of polyimide aerogels cross-linked through a polyhedral oligomeric silsesquioxane, octa(aminophenyl)silsesquioxane (OAPS). Gels formed from polyamic acid solutions of 3,3',4,4'-biphenyltetracarboxylic dianhydride (BPDA), bisaniline-p-xylidene (BAX) and OAPS were chemically imidized and dried using supercritical CO(2) extraction to give aerogels having density around 0.1 g/cm(3). The aerogels are greater than 90 % porous, have high surface areas (230 to 280 m(2)/g) and low thermal conductivity (14 mW/m-K at room temperature). Notably, the polyimide aerogels cross-linked with OAPS have higher modulus than polymer reinforced silica aerogels of similar density and can be fabricated as both monoliths and thin films. Thin films of the aerogel are flexible and foldable making them an ideal insulation for space suits, and inflatable structures for habitats or decelerators for planetary re-entry, as well as more down to earth applications. PMID:21294517

Guo, Haiquan; Meador, Mary Ann B; McCorkle, Linda; Quade, Derek J; Guo, Jiao; Hamilton, Bart; Cakmak, Miko; Sprowl, Guilherme

2011-02-04

68

Bonding aerogels with polyurethanes  

SciTech Connect

Aerogels, porous silica glasses with ultra-fine cell size (30nm), are made by a solution gelation (sol-gel) process. The resulting gel is critical point dried to densities from 0.15--0.60 g/cc. This material is machinable, homogeneous, transparent, coatable and bondable. To bond aerogel an adhesive should have long cure time, no attack on the aerogel structure, and high strength. Several epoxies and urethanes were examined to determine if they satisfied these conditions. Bond strengths above 13 psi were found with double bubble and DP-110 epoxies and XI-208/ODA-1000 and Castall U-2630 urethanes. Hardman Kalex Tough Stuff'' A-85 hardness urethane gave 18 psi bond strength. Hardman A-85, Tuff-Stuff'' was selected for further evaluation because it produced bond strengths comparable to the adherend cohesive strength. 5 refs., 2 figs.

Matthews, F.M.; Hoffman, D.M.

1989-11-01

69

Evaluation of Aerogel Materials for High-Temperature Batteries  

SciTech Connect

Siiica aerogels have 1/3 the thermal conductivity of the best commercial composite insulations, or ~13 mW/m-K at 25°C. However, aerogels are transparent in the near IR region of 4-7 µm, which is where the radiation peak from a thermal-battery stack occurs. Titania and carbon- black powders were examined as thermal opacifiers, to reduce radiation at temperatures between 300°C and 600°C, which spans the range of operating temperature for most thermal batteries. The effectiveness of the various opacifiers depended on the loading, with the best overall results being obtained using aerogels filled with carbon black. Fabrication and strength issues still remain, however.

Ashley, Carol S.; Guidotti, Ronald A.; Reed, Scott T.; Reinhardt, Frederick W.

1999-05-04

70

Innovative Liquid Breeder Blanket Design Activities in Japan  

SciTech Connect

In order to clarify key engineering issues and to enhance key R and D activities for D-T fusion blankets, many design activities on innovative liquid blanket systems are on going as collaboration studies in Japan. Recently an improved long-life Flibe blanket has been proposed, and the self-cooled Li/V blanket design has started. For Flibe systems, much progress has been made on tritium permeation barrier, energy conversion system, free surface designs, and thermofluid loop experiments. For Li/V systems, evaluation studies have proceeded on Be-free nuclear properties and allowable crack fraction on multilayered MHD insulation coatings.

Sagara, Akio [National Institute for Fusion Science (Japan); Tanaka, Teruya [National Institute for Fusion Science (Japan); Muroga, Takeo [National Institute for Fusion Science (Japan); Hashizume, Hidetoshi [Tohoku University (Japan); Kunugi, Tomoaki [Kyoto University (Japan); Fukada, Satoshi [Kyushu University (Japan); Shimizu, Akihiko [Kyushu University (Japan)

2005-04-15

71

21 CFR 582.1711 - Silica aerogel.  

Code of Federal Regulations, 2010 CFR

...2010-04-01 2010-04-01 false Silica aerogel. 582.1711 Section 582.1711 Food and...Purpose Food Additives § 582.1711 Silica aerogel. (a) Product. Silica aerogel as a finely powdered microcellular silica...

2010-04-01

72

21 CFR 582.1711 - Silica aerogel.  

Code of Federal Regulations, 2010 CFR

...2009-04-01 2009-04-01 false Silica aerogel. 582.1711 Section 582.1711 Food and...Purpose Food Additives § 582.1711 Silica aerogel. (a) Product. Silica aerogel as a finely powdered microcellular silica...

2009-04-01

73

21 CFR 182.1711 - Silica aerogel.  

Code of Federal Regulations, 2010 CFR

...2010-01-01 2009-04-01 true Silica aerogel. 182.1711 Section 182.1711 Food and...GRAS Food Substances § 182.1711 Silica aerogel. (a) Product. Silica aerogel as a finely powdered microcellular silica...

2010-01-01

74

21 CFR 182.1711 - Silica aerogel.  

Code of Federal Regulations, 2010 CFR

...2009-04-01 2009-04-01 false Silica aerogel. 182.1711 Section 182.1711 Food and...GRAS Food Substances § 182.1711 Silica aerogel. (a) Product. Silica aerogel as a finely powdered microcellular silica...

2009-04-01

75

Silica aerogel production costs  

SciTech Connect

We performed a cost study for a silica aerogel production plant. It was found that the production costs are dominated by the cost of the base materials, and not by the energy (supercritical extraction) requirements. Alternative production methods using cheaper input materials (process development for TMOS, TEOS ) are needed.

Lewis, D.L.; Carlson, G.A.

1993-01-01

76

Silica aerogel production costs  

SciTech Connect

We performed a cost study for a silica aerogel production plant. It was found that the production costs are dominated by the cost of the base materials, and not by the energy (supercritical extraction) requirements. Alternative production methods using cheaper input materials (process development for TMOS, TEOS?) are needed.

Lewis, D.L.; Carlson, G.A.

1993-01-01

77

Development of optically active aerogels  

SciTech Connect

The objective of this work is to develop the methodology to incorporate specified concentrations of dye molecules within a silica aerogel matrix. Secondary goals are to determine the optical characteristics of the dye-doped aerogel and to determine how the dye molecules are held within the silica matrix. Fluorescence and UV-YIS spectra are used to characterize the dye-doped aerogel. Such spectra can give information about how the dye molecules are bound within the aerogel matrix. 13 figs., 1 tab.

Hrubesh, L.W.; Tillotson, T.M.

1990-10-15

78

Carbon aerogels and xerogels  

SciTech Connect

The aqueous polycondensation of resorcinol with formaldehyde proceeds through a sol-gel transition and results in the formation of highly crosslinked, transparent gels. If the solvent is simply evaporated from the pores of these gels, large capillary forces are exerted and a collapsed structure known as a xerogel is formed. In order to preserve the gel skeleton and minimize shrinkage, the aforementioned solvent or its substitute must be removed under supercritical conditions. The microporous material that results from this operation is known as an aerogel. Because resorcinol-formaldehyde aerogels and xerogels consist of a highly crosslinked aromatic polymer, they can be pyrolyzed in an inert atmosphere to form vitreous carbon monoliths. The resultant porous materials are black in color and no longer transparent, yet they retain the ultrafine cell size (< 50 nm), high surface area (600--800 m[sup 2]/g), and the interconnected particle morphology of their organic precursors. The thermal, acoustic, mechanical, and electrical properties of carbon aerogels/xerogels primarily depend upon polymerization conditions and pyrolysis temperature. In this paper, the chemistry-structure-property relationships of these unique materials will be discussed in detail.

Pekala, R.W.; Alviso, C.T.

1992-04-01

79

Button cell supercapacitors with monolithic carbon aerogels  

Microsoft Academic Search

Carbon aerogels are highly porous materials prepared via pyrolysis of resorcinol–formaldehyde aerogels. The density of the aerogels can be varied in a wide range, whereby the major part of the pores is accessible to ionic conductors. Therefore, the application of high surface area aerogels as electrodes in supercapacitor devices is promising. In the present publication, the integration of thin monolithic

H. Pröbstle; C. Schmitt; J. Fricke

2002-01-01

80

Materials for breeding blankets  

SciTech Connect

There are several candidate concepts for tritium breeding blankets that make use of a number of special materials. These materials can be classified as Primary Blanket Materials, which have the greatest influence in determining the overall design and performance, and Secondary Blanket Materials, which have key functions in the operation of the blanket but are less important in establishing the overall design and performance. The issues associated with the blanket materials are specified and several examples of materials performance are given. Critical data needs are identified.

Mattas, R.F.; Billone, M.C.

1995-09-01

81

Aerogels: production, characterization, and applications  

Microsoft Academic Search

Aerogels are unique materials with many fascinating properties. A scientific curiosity since being prepared in the 1930's, today's research has focused on potential applications and more economic production routes. In this paper, we present a historic review of aerogels while bringing the reader up-to-date on the latest technological developments.

J. Fricke; T Tillotson

1997-01-01

82

Production of hollow aerogel microspheres  

DOEpatents

A method is described for making hollow aerogel microspheres of 800--1200{mu} diameter and 100--300{mu} wall thickness by forming hollow alcogel microspheres during the sol/gel process in a catalytic atmosphere and capturing them on a foam surface containing catalyst. Supercritical drying of the formed hollow alcogel microspheres yields hollow aerogel microspheres which are suitable for ICF targets.

Upadhye, R.S.; Henning, S.A.

1990-12-31

83

Organic carbon aerogels from the sol-gel polymerization of phenolic-furfural mixtures  

DOEpatents

The sol-gel polymerization of a phenolic-furfural mixture in dilute solution leads to a highly cross-linked network that can be supercritically dried to form a high surface area foam. These porous materials have cell/pore sizes .ltoreq.1000 .ANG., and although they are dark brown in color, they can be classified as a new type of aerogel. The phenolic-furfural aerogel can be pyrolyzed in an inert atmosphere at 1050.degree. C. to produce carbon aerogels. This new aerogel may be used for thermal insulation, chromatographic packing, water filtration, ion-exchange, and carbon electrodes for energy storage devices, such as batteries and double-layer capacitors.

Pekala, Richard W. (Pleasant Hill, CA)

1998-04-28

84

Organic aerogels from the sol-gel polymerization of phenolic-furfural mixtures  

DOEpatents

The sol-gel polymerization of a phenolic-furfural mixture in dilute solution leads to a highly cross-linked network that can be supercritically dried to form a high surface area foam. These porous materials have cell/pore sizes.ltoreq.1000.ANG., and although they are dark brown in color, they can be classified as a new type of aerogel. The phenolic-furfural aerogel can be pyrolyzed in an inert atmosphere at 1050.degree. C. to produce carbon aerogels. This new aerogel may be used for thermal insulation, chromatographic packing, water filtration, ion-exchange, and carbon electrodes for energy storage devices, such as batteries and double-layer capacitors.

Pekala, Richard W. (Pleasant Hill, CA)

1995-01-01

85

Organic aerogels from the sol-gel polymerization of phenolic-furfural mixtures  

DOEpatents

The sol-gel polymerization of a phenolic-furfural mixture in dilute solution leads to a highly cross-linked network that can be supercritically dried to form a high surface area foam. These porous materials have cell/pore sizes .ltoreq.1000.ANG., and although they are dark brown in color, they can be classified as a new type of aerogel. The phenolic-furfural aerogel can be pyrolyzed in an inert atmosphere at 1050.degree. C. to produce carbon aerogels. This new aerogel may be used for thermal insulation, chromatographic packing, water filtration, ion-exchange, and carbon electrodes for energy storage devices, such as batteries and double-layer capacitors.

Pekala, Richard W. (Pleasant Hill, CA)

1996-01-01

86

Evaluation of Fire Test Methods for Aircraft Thermal Acoustical Insulation.  

National Technical Information Service (NTIS)

The report presents the results of laboratory round robin flammability testing performed on thermal acoustic insulation blankets and the films used as insulation coverings. The work was requested by the aircraft industry as a result of actual incidents in...

P. Cahill

1997-01-01

87

High power density self-cooled lithium-vanadium blanket.  

SciTech Connect

A self-cooled lithium-vanadium blanket concept capable of operating with 2 MW/m{sup 2} surface heat flux and 10 MW/m{sup 2} neutron wall loading has been developed. The blanket has liquid lithium as the tritium breeder and the coolant to alleviate issues of coolant breeder compatibility and reactivity. Vanadium alloy (V-4Cr-4Ti) is used as the structural material because it can accommodate high heat loads. Also, it has good mechanical properties at high temperatures, high neutron fluence capability, low degradation under neutron irradiation, good compatibility with the blanket materials, low decay heat, low waste disposal rating, and adequate strength to accommodate the electromagnetic loads during plasma disruption events. Self-healing electrical insulator (CaO) is utilized to reduce the MHD pressure drop. A poloidal coolant flow with high velocity at the first wall is used to reduce the peak temperature of the vanadium structure and to accommodate high surface heat flux. The blanket has a simple blanket configuration and low coolant pressure to reduce the fabrication cost, to improve the blanket reliability, and to increase confidence in the blanket performance. Spectral shifter, moderator, and reflector are utilized to improve the blanket shielding capability and energy multiplication, and to reduce the radial blanket thickness. Natural lithium is used to avoid extra cost related to the lithium enrichment process.

Gohar, Y.; Majumdar, S.; Smith, D.

1999-07-01

88

Monolayer coated aerogels and method of making  

DOEpatents

Aerogels having a monolayer coating are described. The aerogel and a monolayer forming precursor are provided in a supercritical fluid, whereupon the aerogel and the monolayer forming precursor are reacted in said supercritical fluid to form a covalent bond between the aerogel and the monolayer forming precursor. Suitable aerogels are ceramic oxides such as silica, alumina, aluminosilicate, and combinations thereof. Suitable monolayer forming precursors include alkyl silanes, chlorosilanes, boranes, chloroboranes, germanes, and combinations thereof. The method may also include providing a surface preparation agent such as water, or hydroetching an aerogel to enhance the coating of the monolayer.

Zemanian, Thomas Samuel (Richland, WA); Fryxell, Glen (Kennwick, WA); Ustyugov, Oleksiy A. (Spokane, WA)

2006-03-28

89

Silica Aerogel Windows in Danish Residential Buildings: Assessment of Possibilities for Energy Conservation.  

National Technical Information Service (NTIS)

The main purpose of this report has been to describe the potential energy saving by replacing all windows in the Danish building stock by highly insulated windows with monolithic silica aerogel, the so-called Airglass-windows. A description of the buildin...

O. Bruun Joergensen

1989-01-01

90

Nanostructural engineering of organic aerogels  

SciTech Connect

Aerogels are a special class of open-cell foams with an ultrafine cell/pore size (<50 nm), high surface area (400-1100 M{sup 2}/g), and a solid matrix composed of interconnected colloidal-like particles or fibers with characteristic diameters of 10 nm. This paper examines the correlation between nanostructure and thermal conductivity in a series of resorcinol-formaldehyde (RF) aerogels prepared under different synthetic conditions.

Pekala, R.W.; Alviso, C.T. [Lawrence Livermore National Lab., CA (United States); Lu, X.; Caps, R.; Frocle, J. [Physikalisches Institut der Universitat Wurzburg, Wurzburg, (Germany)

1995-03-01

91

Low RF Reflectivity Spacecraft Thermal Blanket by Using High-Impedance Surface Absorbers  

NASA Astrophysics Data System (ADS)

A technique for designing a low-RF reflectivity thermal blanket is presented. Multi-layer insulation (MLI) blankets are employed to stabilize the temperature on spacecraft unit but they can be responsible of passive intermodulation products and high-mutual coupling between antennas since they are realized with metallic materials. The possibility to replace the last inner layer of a MLI blanket with an ultra-thin absorbing layer made of high-impedance surface absorber is discussed.

Costa, F.; Monorchio, A.; Carrubba, E.; Zolesi, V.

2012-05-01

92

Analysis of ER string test thermally instrumented interconnect 80-K MLI blanket  

Microsoft Academic Search

An 80-K Multi Layer Insulation (MLI) blanket in the interconnect region between magnets DD0019 and DD0027 in the Fermi National Accelerator Laboratory (FNAL) ER string was instrumented with temperature sensors to obtain the steady-state temperature gradient through the blanket after string cooldown. A thermal model of the 80-K blanket assembly was constructed to analyze the steady-state temperature gradient data. Estimates

E. Daly; R. Pletzer

1992-01-01

93

Low RF reflectivity spacecraft thermal blanket by using high-impedance surface absorbers  

Microsoft Academic Search

A technique for designing a low-RF reflectivity thermal blanket is presented. Multi-layer insulation (MLI) blankets are employed to stabilize the temperature on spacecraft unit but they can be responsible of passive intermodulation products and high-mutual coupling between antennas since they are realized with metallic materials. The possibility to replace the last inner layer of a MLI blanket with an ultra-thin

Filippo Costa; Agostino Monorchio; Elisa Carrubba; Valfredo Zolesi

2012-01-01

94

Helium Cooled Flibe Blanket.  

National Technical Information Service (NTIS)

The blanket design uses a pressure vessel to contain the 50 atmosphere helium gas. Helium cools the first wall and blanket internals. The internals consist of a bed of beryllium balls nominally 1 cm diameter in which neutrons are multiplied and later capt...

R. Moir

1984-01-01

95

Helium cooled Flibe blanket  

Microsoft Academic Search

The blanket design uses a pressure vessel to contain the 50 atmosphere helium gas. Helium cools the first wall and blanket internals. The internals consist of a bed of beryllium balls nominally 1 cm diameter in which neutrons are multiplied and later captured, breeding adequate (even excess) amounts of tritium and releasing energy in exothermic nuclear reactions. Tritium is bred

Moir

1984-01-01

96

Physics of Interplanetary Dust Collection with Aerogel.  

National Technical Information Service (NTIS)

This report presents the results of research undertaken to study various problems associated with hypervelocity capture of dust particles in aerogel. The primary topics investigated were the properties of shocked aerogel and the requirements for reliable ...

W. W. Anderson

1998-01-01

97

Aerogel Algorithm for Shrapnel Penetration Experiments  

Microsoft Academic Search

To aid in assessing shrapnel produced by laser-irradiated targets, we have performed shrapnel collection ``BB gun'' experiments in aerogel and have developed a simple analytical model for deceleration of the shrapnel particles in the aerogel. The model is similar in approach to that of Anderson and Ahrens (J. Geophys. Res., 99 El, 2063-2071, Jan. 1994) and accounts for drag, aerogel

R. E. Tokheim; D. C. Erlich; D. R. Curran; M. Tobin; D. Eder

2004-01-01

98

Vacuum-dried robust bridged silsesquioxane aerogels.  

PubMed

Robust aerogels derived from a thiol-ene clicked bridged silsesquioxane precursor are obtained by a facile vacuum-drying method. With rather low densities, the flexible aerogels are still robust enough to bear at least 20 repeating compressions and further functionalization by wet doping. The durability and facile preparation procedure promise the aerogels' wider practical applications. PMID:23784876

Wang, Zhen; Dai, Zhen; Wu, Junjie; Zhao, Ning; Xu, Jian

2013-06-20

99

Fusion blanket inherent safety assessment  

SciTech Connect

The inherent safety aspect of TPSS reactor blankets has been investigated. The idea is to design the blanket so safe that cost savings can be realized such as through non-nuclear grading construction. If the blanket materials are carefully selected, inherent safety is feasible for fusion reactor blankets up to 5 to 10 MW/m/sup 2/ neutron wall loading.

Sze, D.K.; Jung, J.; Cheng, E.T.

1986-01-01

100

MHD considerations for a self-cooled liquid lithium blanket  

SciTech Connect

The magnetohydrodynamic (MHD) effects can present a feasibility issue for a self-cooled liquid metal blanket of magnetically confined fusion reactors, especially inboard regime of a tokamak. This pressure drop can be significantly reduced by using insulated wall structure. A self-healing insulating coating has been identified, which will reduce the pressure drop by more than a factor of 10. The future research direction to further quantify the performance of this coating is also outlined.

Sze, D.K.; Mattas, R.F.; Hull, A.B.; Picologlou, B.F.; Smith, D.L.

1992-03-01

101

Performance of uncoated AFRSI blankets during multiple Space Shuttle flights  

NASA Astrophysics Data System (ADS)

Uncoated Advanced Flexible Reusable Surface Insulation (AFRSI) blankets were successfully flown on seven consecutive flights of the Space Shuttle Orbiter OV-099 (Challenger). In six of the eight locations monitored (forward windshield, forward canopy, mid-fuselage, upper wing, rudder/speed brake, and vertical tail) the AFRSI blankets performed well during the ascent and reentry exposure to the thermal and aeroacoustic environments. Several of the uncoated AFRSI blankets that sustained minor damage, such as fraying or broken threads, could be repaired by sewing or by patching with a surface coating called C-9. The chief reasons for replacing or completely coating a blanket were fabric embrittlement and fabric abrasion caused by wind erosion. This occurred in the orbiter maneuvering system (OMS) pod sidewall and the forward mid-fuselage locations.

Sawko, Paul M.; Goldstein, Howard E.

1992-04-01

102

U.S. technical report for the ITER blanket/shield: A. blanket: Topical report, July 1990--November 1990  

SciTech Connect

Three solid-breeder water-cooled blanket concepts have been developed for ITER based on a multilayer configuration. The primary difference among the concepts is in the fabricated form of breeder and multiplier. All the concepts have beryllium for neutron multiplication and solid-breeder temperature control. The blanket design does not use helium gaps or insulator material to control the solid breeder temperature. Lithium oxide (Li{sub 2}O) and lithium zirconate (Li{sub 2}ZrO{sub 3}) are the primary and the backup breeder materials, respectively. The lithium-6 enrichment is 95%. The use of high lithium-6 enrichment reduces the solid breeder volume required in the blanket and consequently the total tritium inventory in the solid breeder material. Also, it increases the blanket capability to accommodate power variation. The multilayer blanket configuration can accommodate up to a factor of two change in the neutron wall loading without violating the different design guidelines. The blanket material forms are sintered products and packed bed of small pebbles. The first concept has a sintered product material (blocks) for both the beryllium multiplier and the solid breeder. The second concept, the common ITER blanket, uses a packed bed breeder and beryllium blocks. The last concept is similar to the first except for the first and the last beryllium zones. Two small layers of beryllium pebbles are located behind the first wall and the back of the last beryllium zone to reduce the total inventory of the beryllium material and to improve the blanket performance. The design philosophy adopted for the blanket is to produce the necessary tritium required for the ITER operation and to operate at power reactor conditions as much as possible. Also, the reliability and the safety aspects of the blanket are enhanced by using low-pressure water coolant and the separation of the tritium purge flow from the coolant system by several barriers.

Not Available

1995-01-01

103

Status of aerogel production in Novosibirsk  

NASA Astrophysics Data System (ADS)

Silica aerogel blocks are being produced for use in Cherenkov detectors by a collaboration of Boreskov Institute of Catalysis and Budker Institute of Nuclear Physics since 1986. Novosibirsk aerogel is used in several detectors; among them are KEDR, SND (BINP, Novosibirsk), LHCb (CERN, Geneva), AMS (for International Space Station mission) and others. Currently our investigations are going on in two directions: multilayer aerogels for Focusing Aerogel RICH and aerogels with high index of refraction. We have synthesized two-, three- and four-layer aerogel tiles with dimensions of 115 mm×115 mm. We have modernized the method of pinhole drying for preparation of aerogels with refractive index in the range of 1.07-1.20.

Barnyakov, A. Yu.; Barnyakov, M. Yu.; Beloborodov, K. I.; Bobrovnikov, V. S.; Buzykaev, A. R.; Golubev, V. B.; Gulevich, B. V.; Danilyuk, A. F.; Kononov, S. A.; Kravchenko, E. A.; Martin, K. A.; Onuchin, A. P.; Porosev, V. V.; Serednyakov, S. I.

2011-05-01

104

The conversion of a room temperature NaK loop to a high temperature MHD facility for Li\\/V blanket testing  

Microsoft Academic Search

The Vanadium\\/Lithium system has been the recent focus of ANL`s Blanket Technology Pro-ram, and for the last several years, ANL`s Liquid Metal Blanket activities have been carried out in direct support of the ITER (International Thermonuclear Experimental Reactor) breeding blanket task area. A key feasibility issue for the ITER Vanadium\\/Lithium breeding blanket is the Near the development of insulator coatings.

C. B. Reed; R. C. Haglund; M. E. Miller; J. R. Nasiatka; I. R. Kirillov; A. P. Ogorodnikov; G. V. Preslitski; G. P. Goloubovitch; Zeng Yu Xu

1996-01-01

105

Conversion of a room temperature NaK loop to a high temperature MHD facility for Li\\/V blanket testing  

Microsoft Academic Search

The Vanadium\\/Lithium system has been the recent focus of ANL`s Blanket Technology Program, and for the last several years, ANL`s Liquid Metal Blanket activities have been carried out in direct support of the ITER (International Thermonuclear Experimental Reactor) breeding blanket task area. A key feasibility issue for the ITER Vanadium\\/Lithium breeding blanket is the development of insulator coatings. Design calculations,

C. B. Reed; R. C. Haglund; M. E. Miller; J. R. Nasiatka; I. R. Kirillov; A. P. Ogorodnikov; G. V. Preslitski; G. P. Goloubovitch; Z. Y. Xu

1996-01-01

106

Perioperative thermal insulation.  

PubMed

To determine the efficacy of passive insulators advocated for prevention of cutaneous heat loss, we determined heat loss in unanesthetized volunteers covered by one of the following: a cloth "split sheet" surgical drape; a Convertors disposable-paper split sheet; a Thermadrape disposable laparotomy sheet; an unheated Bair Hugger patient-warming blanket; 1.5-mil-thick plastic hamper bags; and a prewarmed, cotton hospital blanket. Cutaneous heat loss was measured using 10 area-weighted thermal flux transducers while volunteers were exposed to a 20.6 degrees C environment for 1 h. Heat loss decreased significantly from 100 +/- 3 W during the control periods to 69 +/- 6 W (average of all covers) after 1 h of treatment. Heat losses from volunteers insulated by the Thermadrape (61 +/- 6 W) and Bair Hugger covers (64 +/- 5 W) were significantly less than losses from those insulated by plastic bags (77 +/- 11 W). The paper drape (67 +/- 7 W) provided slightly, but not significantly, better insulation than the cloth drape (70 +/- 4 W). Coverage by prewarmed cotton blankets initially resulted in the least heat loss (58 +/- 8 W), but after 40 min, resulted in heat loss significantly greater than that for the Thermadrape (71 +/- 7 W). Regional heat loss was roughly proportional to surface area, and the distribution of regional heat loss remained similar with all covers. These data suggest that cost and convenience should be major factors when choosing among passive perioperative insulating covers. It is likely that the amount of skin surface covered is more important than the choice of skin region covered or the choice of insulating material. PMID:2021204

Sessler, D I; McGuire, J; Sessler, A M

1991-05-01

107

Effective emittance measurements on clamshell-wrapped multi-layer insulation for half inch tubing  

Microsoft Academic Search

The three clamshell-wrapped multi-layer insulation (MLI) blankets for Space Station external fuel lines have been subjected to effective emittance measurements. Tube target temperatures were of the order of 110 to -40 F. While blanket no. 1 was modeled after that currently used on the Space Shuttle Orbiter, the no. and no. 3 blankets were designed to reduce heat leakage through

C. A. Stobb

1993-01-01

108

Prediction of Mechanical Properties of Aerogels using a Multifractal Multidimensional Multiscaling Approach  

NASA Astrophysics Data System (ADS)

Aerogels, produced by sol-gel technologies, have several applications in sensors, high energy particle physics, catalysis, heat insulation, supercapacitors, heat storage devices, high efficiency windows, among others. These applications take advantage of the outstanding properties these materials present as a result of their structure. However, the low mechanical properties that these materials present as result of the process, limits their commercial applications. In this dissertation, it is investigated the relationship between the processing conditions and mechanical properties of these materials computationally. The prediction of the effective properties for these materials is a daunting task because of their complex structure. Aerogels's structure is not homogeneous nor periodic, but rather amorphous, nanostructured, and highly porous, making the traditional techniques used to study other materials inapplicable. This dissertation presents the prediction of mechanical properties of aerogels calculated by a novel Multifractal Multidimensional Multiscaling Approach (MMMA) developed here. MMMA consists on recursively calculating the effective properties of the material along several scales. Since aerogels and structures produced by sol-gel technologies present a multifractal character, it is shown that MMMA is applicable to predict the effective properties of these materials. The implementation of MMMA requires a fractal characterization of the structure. For this, computational scattering experiments were performed on structures resembling aerogels. The structures resembling aerogels were produced computationally incorporating the chemistry and the physical phenomena involved in the formation process. MMMA was used to predict the mechanical properties of silica aerogels for different processing conditions. Thus, mechanical properties, scattering experiments, and processing conditions were investigated and correlated in this work.

Campo Schickler, Fritz Andres

109

Multilayer thermal insulation tests  

NASA Astrophysics Data System (ADS)

The main purpose of this work is to make experimental measurements of the effective emittance of Multilayer Thermal Insulation (MLI) constructed from Brazilian materials. The emissivities obtained are compared with theoretical and literary references. Heat is carefully calculated and a study of the resulting uncertainties made. The results obtained are encouraging and it is possible to produce and furnish the neceassary thermal blankets for Brazilian satellites. New materials are sought and additional MLI configurations will be tested.

Mantelli, Marcia Barbosa H.

1988-02-01

110

Method for Nanoencapsulation of Aerogels and Nanoencapsulated Aerogels Produced by Such Method.  

National Technical Information Service (NTIS)

A method for increasing the compressive modulus of aerogels comprising: providing aerogel substrate comprising a bubble matrix in a chamber; providing monomer to the chamber, the monomer comprising vapor phase monomer which polymerizes substantially free ...

T. A. Sullivan

2004-01-01

111

Method for Nanoencapsulation of Aerogels and Nanoencapsulated Aerogels Produced by such Method (2007).  

National Technical Information Service (NTIS)

A method for increasing the compressive modulus of aerogels comprising: providing aerogel substrate comprising a bubble matrix in a chamber; providing monomer to the chamber, the monomer comprising vapor phase monomer which polymerizes substantially free ...

T. A. Sullivan

2007-01-01

112

Desalination with carbon aerogel electrodes  

SciTech Connect

An electrically regenerated electrosorption process known as carbon aerogel CDI was developed for continuously removing ionic impurities from aqueous streams. A salt solution flows in a channel formed by pairs of parallel carbon aerogel electrodes. Each electrode has a very high BET surface area and very low resistivity. After polarization, anions and cations are removed from electrolyte by the electric field and electrosorbed onto the carbon aerogel. The solution is thus separated into two streams, brine and water. Based on this, carbon aerogel CDI appears to be an energy-efficient alternative to evaporation, electrodialysis, and reverse osmosis. The energy required by this process is about QV/2, plus losses. Estimated energy requirement for sea water desalination is 18-27 Wh gal{sup -1}, depending on cell voltage and flow rate. The requirement for brackish water desalination is less, 1.2-2.5 Wh gal{sup -1} at 1600 ppM. This is assuming that stored electrical energy is reclaimed during regeneration.

Farmer, J.C.; Richardson, J.H.; Fix, D.V.

1996-10-21

113

Some applications of silica aerogels  

Microsoft Academic Search

Silica aerogels are very highly divided materials which are synthesised through the association of a chemical step, the so-called sol–gel chemistry, with a physical step which is a particular way of drying the wet gel, namely under supercritical conditions with respect to the liquid phase filling its porosity. This drying process preserves the texture of the dry material: in practice

Gerard Marcel Pajonk

2003-01-01

114

ITER breeding blanket design  

SciTech Connect

A breeding blanket design has been developed for ITER to provide the necessary tritium fuel to achieve the technical objectives of the Enhanced Performance Phase. It uses a ceramic breeder and water coolant for compatibility with the ITER machine design of the Basic Performance Phase. Lithium zirconate and lithium oxide am the selected ceramic breeders based on the current data base. Enriched lithium and beryllium neutron multiplier are used for both breeders. Both forms of beryllium material, blocks and pebbles are used at different blanket locations based on thermo-mechanical considerations and beryllium thickness requirements. Type 316LN austenitic steel is used as structural material similar to the shielding blanket. Design issues and required R&D data are identified during the development of the design.

Gohar, Y.; Cardella, A.; Ioki, K.; Lousteau, D.; Mohri, K.; Raffray, R.; Zolti, E. [ITER Joint Central Team, Garching (Germany)] [and others

1995-12-31

115

Tritiation of aerogel matrices: T2O, tritiated organics and tritium exchange on aerogel surfaces.  

National Technical Information Service (NTIS)

Three methods for incorporation of tritium into the phoshor/aerogel matrix have been demonstrated: (1) adsorption of T(sub 2)O by the aerogel, (2) incorporation of tritiated organic into the pores of the aerogel and (3) isotopic exchange of tritium from T...

R. E. Ellefson J. T. Gill T. J. Shepodd L. E. Leonard

1990-01-01

116

Aerogels derived from multifunctional organic monomers  

SciTech Connect

Traditional inorganic aerogels are mad via the hydrolysis and condensation of metal alkoxides. Recently, we reported the synthesis of organic aerogels based upon the aqueous polycondensation of (1) resorcinol with formaldehyde and (2) melamine with formaldehyde. The former materials can also be pyrolyzed in an inert atmosphere to form vitreous carbon aerogels. In both the inorganic and organic systems, the structure and properties of the dried aerogel are dictated by polymerization conditions. Factors such as pH, reactant ratio, and temperature influence the crosslinking chemistry and growth processes taking place prior to gelation. The ability to tailor the structure and properties of aerogels at the nanometer scale opens up exciting possibilities for these novel materials. This paper addresses the chemistry-structure-property relationships of organic aerogels. 22 refs., 7 figs.

Pekala, R.W.; Alviso, C.T.; Kong, F.M.; Hulsey, S.S.

1991-09-01

117

Development of aerogel Cherenkov detectors at Novosibirsk  

Microsoft Academic Search

The development of aerogel Cherenkov counters with the light collection using a wavelength shifter is described. 80 counters of this type are working in the KEDR detector. A project of similar counters for the SND detector based on “heavy” aerogel with n=1.13 has been developed. Aerogel with a refractive index of 1.006–1.13 and dimensions of blocks up to 200×200×50mm3 is

A. Yu. Barnyakov; M. Yu. Barnyakov; J. Bähr; T. Bellunato; K. I. Beloborodov; V. S. Bobrovnikov; A. R. Buzykaev; M. Calvi; A. F. Danilyuk; V. Djordjadze; V. B. Golubev; S. A. Kononov; E. A. Kravchenko; D. Lipka; C. Matteuzzi; M. Musy; A. P. Onuchin; D. Perego; V. A. Rodiakin; G. A. Savinov; S. I. Serednyakov; A. G. Shamov; F. Stephan; V. A. Tayursky; A. I. Vorobiov

2005-01-01

118

Ultralight and highly compressible graphene aerogels.  

PubMed

Chemically converted graphene aerogels with ultralight density and high compressibility are prepared by diamine-mediated functionalization and assembly, followed by microwave irradiation. The resulting graphene aerogels with density as low as 3 mg cm(-3) show excellent resilience and can completely recover after more than 90% compression. The ultralight graphene aerogels possessing high elasticity are promising as compliant and energy-absorbing materials. PMID:23418081

Hu, Han; Zhao, Zongbin; Wan, Wubo; Gogotsi, Yury; Qiu, Jieshan

2013-02-18

119

High surface area carbon aerogels for supercapacitors  

Microsoft Academic Search

Applications of carbon aerogels as electrodes in supercapacitors require high surface area and simple production method. Carbon aerogels are derived via the pyrolysis of resorcinol-formaldehyde (RF) aerogels. In order to simplify production, subcritical drying of the RF gels is favoured, which is possible for gels prepared with high molar resorcinol to catalyst (R\\/C) ratios, i.e. very low catalyst concentrations. Resulting

R. Saliger; U Fischer; C Herta; J Fricke

1998-01-01

120

Hypervelocity impact experiments on aerogel dust collector  

Microsoft Academic Search

Laboratory hypervelocity impact experiments were conducted to verify the performance of aerogel dust collectors used for gathering meteoroids and space debris in the near-Earth environment and to derive the relationships of various parameters characterizing the projectile with morphology of tracks left by the penetrating projectile in the aerogel collector pad. Silica aerogel collectors of 0.03 g\\/cm3 density were impacted at

Yukihito Kitazawa; Akira Fujiwara; Toshihiko Kadono; Kichiro Imagawa; Yutaka Okada; Kazuo Uematsu

1999-01-01

121

Analysis of ER string test thermally instrumented interconnect 80-K MLI blanket  

SciTech Connect

An 80-K Multi Layer Insulation (MLI) blanket in the interconnect region between magnets DD0019 and DD0027 in the Fermi National Accelerator Laboratory (FNAL) ER string was instrumented with temperature sensors to obtain the steady-state temperature gradient through the blanket after string cooldown. A thermal model of the 80-K blanket assembly was constructed to analyze the steady-state temperature gradient data. Estimates of the heat flux through the 80-K MLI blanket assembly and predicted temperature gradients were calculated. The thermal behavior of the heavy polyethylene terapthalate (PET) cover layers separating the shield and inner blanket and inner and outer blankets was derived empirically from the data. The results of the analysis predict a heat flux of 0.363--0.453 W/m{sup 2} based on the 11 sets of data. These flux values are 33--46% below the 80-K MLI blanket heat leak budget of 0.676 W/m{sup 2}. The effective thermal resistance of the two heavy PET cover layers between the shield and inner blanket was found to be 2.1 times that of a single PET spacer layer, and the effective resistance of the two heavy PET cover layers between the inner blanket and outer blanket was found to be 7 times that of a single PET spacer layer. Based on these results, the 80-K MLI blanket assembly appears to be performing more than adequately to meet the 80-K static IR heat leak budget. However, these results should not be construed as a verification of the 80-K static IR heat leak, since no actual heat leak was measured. The results have been used to improve the empirically based model data in the 80-K MLI blanket thermal model, which has previously not included the effects of heavy PET cover layers on 80-K MLI blanket thermal performance.

Daly, E.; Pletzer, R.

1992-04-01

122

Development of Improved Flammability Criteria for Aircraft Thermal Acoustic Insulation.  

National Technical Information Service (NTIS)

A large number of small-, intermediate-, and full-scale flame propagation tests representative of an in-flight fire were conducted on various thermal acoustic insulation blanket materials. Results indicated that the current Federal Aviation Administration...

T. Marker

2000-01-01

123

Improving the thermal performance of single-glazed windows using translucent granular aerogel  

Microsoft Academic Search

Cost-effective materials, products and installation methods are required to improve the energy efficiency of the UK's existing building stock. The aim of this paper is to assess the potential for high-performance translucent granular aerogel insulation to be retrofitted over single glazing to reduce heat loss without blocking out all of the useful natural light. In situ testing of a 10-mm-thick

Mark Dowson; David Harrison; Salmaan Craig; Zachary Gill

2011-01-01

124

Multiple layer thermal insulation device  

SciTech Connect

A thermal insulation device is described comprising a modular or block insulation composed of at least two layers of serpentine folded fibrous insulating blankets with the layers of blankets being secured by means of extended folds of the hot face layer being interengaged with folds of the cold face layer, with the cold face layer then being separately secured to attachment means for mounting the block on the wall, ceiling, door or other surface of a furnace, kiln or like structure. The layers of fiber are commonly composed of fibers of different compositions, with the more thermally resistant fiber comprising the outer or hot face layer and the less thermally resistant composition comprising the inner or cold face layer.

Cimochowski, A.E.; Heffelmire, B.A.

1982-07-20

125

Summary report for ITER task - T68: MHD facility preparation for Li\\/V blanket option  

Microsoft Academic Search

A key feasibility issue for the ITER Vanadium\\/Lithium breeding blanket is the question of insulator coatings. Design calculations show that an electrically insulating layer is necessary to maintain an acceptably low MHD pressure drop. To enable experimental investigations of the MHD performance of candidate insulator materials and the technology for putting them in place, the room-temperature ALEX (Argonne`s Liquid Metal

C. B. Reed; R. C. Haglund; M. E. Miller

1995-01-01

126

Thermal performance measurements of a 100 percent polyester MLI (multilayer insulation) system for the Superconducting Super Collider  

Microsoft Academic Search

The plastic materials used in the multilayer insulation (MLI) blankets of the superconducting magnets of the Superconducting Super Collider (SSC) are comprised entirely of polyesters. This paper reports on tests conducted in three separate experimental blanket arrangements. The tests explore the thermal performance of two candidate blanket joint configurations each employing a variation of a stepped-butted joint nested between sewn

J. D. Gonczy; W. N. Boroski; R. C. Niemann

1989-01-01

127

Synthesis and Characterization of Vanadium Oxide Aerogels.  

National Technical Information Service (NTIS)

Vanadium pentoxide aerogels were synthesized by supercritical drying with CO2. The aerogels were prepared using a variety of sol compositions from the system VO(OC3H7)3/H2O/acetone. The materials were found to be of fairly low density (0.04g/cu cm to 0. l...

F. Chaput B. Dunn P. Fuqua K. Salloux

1995-01-01

128

A fractal model for superionic aerogels  

Microsoft Academic Search

Ion conducting aerogels are a new class of superionic conductors expected to have interesting properties. Aerogels are extremely porous and have very high surface area. Such porous materials often exhibit self-similarity in structure within certain length scales, so they can be modelled as fractals. This is confirmed by small angle neutron and x-ray scattering experiments. In the present paper we

Shashwati Roy; Ruma Dasgupta; S. Tarafdar

1996-01-01

129

Polyurethane-based organic aerogels' thermal performance  

Microsoft Academic Search

A novel type of chemistry based on the use of polyisocyanates which can be turned into heavily cross-linked polyurethanes (PUR), polyureas, polyurethone imines or polyisocyanurates (PIR) to make organic aerogels is now being developed. Feasibility study of the polyisocyanate-based aerogels and various parameter effects on the thermal performance of these materials are described. This paper focuses on the low density

G. Biesmans; D. Randall; E. Francais; M. Perrut

1998-01-01

130

Thermal expansion of carbon and silica aerogels above room temperature  

Microsoft Academic Search

Thermal expansion of aerogels was studied from 30 to 130°C for silica aerogels and up to 1000°C for carbon aerogels. Measurements were performed in air and in vacuum with different heating\\/cooling rates. The upper temperature limit is determined by partially irreversible shrinkage of silica aerogels due to condensation reactions and by the pyrolysis temperature range for carbon aerogels (1050–2100°C). The

J. Gross; J. Fricke

1995-01-01

131

COMPARATIVE THERMOPHYSIOLOGICAL TESTS ON BLANKETS MADE FROM WOOL AND ACRYLIC-FIBRE–COTTON BLENDS  

Microsoft Academic Search

An account is given of the determination of the thermophysiological properties of two blankets, one made from wool and the other from an acrylic-fibre–cotton blend but otherwise matched in weight and fibre diameter, by laboratory measurements as well as by climatic-chamber tests with human subjects.The tests show that the blanket made from wool confers a higher degree of thermal insulation

K. H. Umbach

1986-01-01

132

Chemistry in an inorganic-organic hybrid aerogel: Chitosan-silica aerogel  

NASA Astrophysics Data System (ADS)

In this thesis, chemistry in a nanoporous inorganic-organic hybrid aerogel (X-silica aerogel) has been explored. The aerogel typically consisted of 10%w/w bioderived polymer (chitosan), and 90%w/w inorganic silica, which interact at the molecule level. The aerogel has a low density in the range of 0.2--0.3 g/cm3, high surface area in the range of 500--950m 2/g, and large pore volume about 90%. The pores are about 3--5 nm in diameter and the size of the primary particles comprising the aerogel network is about 1.5nm. Chemical studies of X-silica aerogels were carried out in the first instance with organic molecules, including dansyl chloride (DC), succinic anhydride (SA), bis(4-isocynatocyclohexyl) methane (HMDI), and isocyanatoethyl methacrylate (IEMA). These reactions lead to modified X-silica aerogel products imparted with valuable functionalities, including fluorescence, carboxylic acid groups, and pendant isocyanate and methacrylate groups. The functionalized aerogels then were utilized to form novel composites. The isocyanate functionalized aerogels were combined with amine-containing silicone polymers to produce aerogel-silicone polymer composites, and methacrylate functionalized aerogels were reacted with hydroxyethylmethacrylate (HEMA) monomer to produce aerogel-polyHEMA composites. The chemical studies were extended to gold-ion Au(III)-X-silica aerogels. Photoreduction of the Au(IIl)-X-silica aerogels by UV irradiation at 254nm reduced the Au(III) ions into Au(0) nanoparticles (AuNPs) while oxidizing the chitosan. Various sizes of AuNPs, with mean diameters from 8--87nm were obtained by varying the Au(III) ions concentration in aerogels from Au(III)/-NH 2 (-NH2 amine groups on chitosan) ratio 1:120 to 1:5. The intensity and time of exposure to the UV light were varied to explore their effect. Two dimensional patterns of Au(0)-X-silica aerogels were achieved by UV irradiation through a mask. Photo-reduction of Au(III)-X-silica aerogels in the presence of various thiols and disulfides leads to functionalized Au nanoparticles by the strong chemisorption of sulfurs and Au nanoparticles. Moreover, when these are present during the photolysis they control the growth of the gold nanoparticles.

Liu, Xipeng

133

Uncooled thin film infrared imaging device with aerogel thermal isolation: Deposition and planarization techniques  

SciTech Connect

The authors have successfully integrated a thermally insulating silica aerogel thin film into a new uncooled monolithic thin film infrared (IR) imaging device. Compared to other technologies (bulk ceramic and microbridge), use of an aerogel layer provides superior thermal isolation of the pyroelectric imaging element from the relatively massive heat sinking integrated circuit. This results in significantly higher thermal and temporal resolutions. They have calculated noise equivalent temperature differences of 0.04--0.10 C from a variety of Pb{sub x}Zr{sub y}Ti{sub 1{minus}y}O{sub 3} (PZT) and Pb{sub x}La{sub 1{minus}x}Zr{sub y}Ti{sub 1{minus}y}O{sub 3} (PLZT) pyroelectric imaging elements in monolithic structures. In addition, use of aerogels results in an easier, less expensive fabrication process and a more robust device. Fabrication of these monolithic devices entails sol-gel deposition of the aerogel, sputter deposition of the electrodes, and solution chemistry deposition of the pyroelectric imaging elements. Uniform pyroelectric response is achieved across the device by use of appropriate planarization techniques. These deposition and planarization techniques are described. Characterization of the individual layers and monolithic structure using scanning electron microscopy, atomic force microscopy and Byer-Roundy techniques also is discussed.

Ruffner, J.A.; Clem, P.G.; Tuttle, B.A.; Brinker, C.J. [Sandia National Labs., Albuquerque, NM (United States); Sriram, C.S. [Univ. of New Mexico, Albuquerque, NM (United States). Dept. of Chemical and Nuclear Engineering; Bullington, J.A. [AMMPEC, Inc., Albuquerque, NM (United States)

1998-04-01

134

Thermal performance of a liquid hydrogen tank multilayer insulation system at warm boundary temperatures of 630, 530, and 152 R  

Microsoft Academic Search

The results are presented of a study conducted to obtain experimental heat transfer data on a liquid hydrogen tank insulated with 34 layers of MLI (multilayer insulation) for warm side boundary temperatures of 630, 530, and 150 R. The MLI system consisted of two blankets, each blanket made up of alternate layers of double silk net (16 layers) and double

Robert J. Stochl; Richard H. Knoll

1991-01-01

135

Uncooled thin film pyroelectric IR detector with aerogel thermal isolation  

SciTech Connect

Uncooled pyroelectric IR imaging systems, such as night vision goggles, offer important strategic advantages in battlefield scenarios and reconnaissance surveys. Until now, the current technology for fabricating these devices has been limited by low throughput and high cost which ultimately limit the availability of these sensor devices. We have developed and fabricated an alternative design for pyroelectric IR imaging sensors that utilizes a multilayered thin film deposition scheme to create a monolithic thin film imaging element on an active silicon substrate for the first time. This approach combines a thin film pyroelectric imaging element with a thermally insulating SiO{sub 2} aerogel thin film to produce a new type of uncooled IR sensor that offers significantly higher thermal, spatial, and temporal resolutions at a substantially lower cost per unit. This report describes the deposition, characterization and optimization of the aerogel thermal isolation layer and an appropriate pyroelectric imaging element. It also describes the overall integration of these components along with the appropriate planarization, etch stop, adhesion, electrode, and blacking agent thin film layers into a monolithic structure. 19 refs., 8 figs., 6 tabs.

Ruffner, J.A.; Clem, P.G.; Tuttle, B.A. [and others

1998-01-01

136

Radon adsorption on an aerogel  

NASA Astrophysics Data System (ADS)

Radon is an important radioactive gas, responsible for environmental exposures and subsequent impact on human health. It is a Noble gas and under most circumstances is not chemically reactive. Its physical properties and resultant behavior, however, may not be simple in all cases, especially where barriers to free diffusion are present, or when encountering materials with special properties. The importance of radon comes from its radioactivity, by imparting energy in material after decay, with resulting damage to living tissue. Transport in the environment is controlled by its physical properties, since it is chemically inert. Aerogels made of silica glass are a relatively new material with the unique property of having a very large surface area, on the order of hundreds of m2 per gram, compared to the exterior surface of the bulk volume of typical solid materials. Insight may be gained into the behavior of both radon and unique materials by observing how radon interacts with such materials. Silica aerogel monoliths with bulk densities of approximately 0.25 g cm-3 were manufactured and exposed to radon gas diffusing freely into the gel using a closed chamber. Measurements were taken while allowing the gas to diffuse out of the gel. Radon is found to diffuse out of the sample chamber at about the same rate when a gel material is present as from an empty chamber. Long-term measurements show radioactivity (from progeny) remains present leading to the conclusion that, the radon may have penetrated some distance into the gel. This leaves open the possibility of applying aerogels as a radon detector. The aerogel manufactured in this study did not preferentially absorb radon. Some evidence suggests that radon may have penetrated the surface however, based on increased long-term radioactivity. Doping the gel with cerium salts, known to cause glass produced by melting processes to scintillate when exposed to ionizing radiation did not produce observable light signal distinguishable from Cerenkov radiation, thereby excluding the hypothesis that the cerium will scintillate in the current arrangement.

Schopfer, Carl J.

137

Synthesis and characterization of a nanocrystalline diamond aerogel  

PubMed Central

Aerogel materials have myriad scientific and technological applications due to their large intrinsic surface areas and ultralow densities. However, creating a nanodiamond aerogel matrix has remained an outstanding and intriguing challenge. Here we report the high-pressure, high-temperature synthesis of a diamond aerogel from an amorphous carbon aerogel precursor using a laser-heated diamond anvil cell. Neon is used as a chemically inert, near-hydrostatic pressure medium that prevents collapse of the aerogel under pressure by conformally filling the aerogel’s void volume. Electron and X-ray spectromicroscopy confirm the aerogel morphology and composition of the nanodiamond matrix. Time-resolved photoluminescence measurements of recovered material reveal the formation of both nitrogen- and silicon- vacancy point-defects, suggesting a broad range of applications for this nanocrystalline diamond aerogel.

Pauzauskie, Peter J.; Crowhurst, Jonathan C.; Worsley, Marcus A.; Laurence, Ted A.; Kilcoyne, A. L. David; Wang, Yinmin; Willey, Trevor M.; Visbeck, Kenneth S.; Fakra, Sirine C.; Evans, William J.; Zaug, Joseph M.; Satcher, Joe H.

2011-01-01

138

Low density, resorcinol-formaldehyde aerogels  

SciTech Connect

This patent describes the polycondensation of resorcinol with formaldehyde under alkaline conditions results in the formation of surface functionalized polymer Clusters. The covalent crosslinking of these clusters produces gels which when processed under supercritical conditions, produce low density, organic aerogels (density {le} 100 mg/cc; cell size {le} 0.1 microns). The aerogels are transparent, dark red in color and consist of interconnected colloidal-like particles with diameters of about 100. These aerogels may be further carbonized to form low density carbon foams with cell size of about 0.1 micron.

Pekala, R.

1991-03-05

139

Affordable Window Insulation with R-10/inch Rating  

SciTech Connect

During the performance of contract DE-FC26-00-NT40998, entitled ''Affordable Window Insulation with R-10/inch Value'', research was conducted at Aspen Aerogels, Inc. to develop new transparent aerogel materials suitable for window insulation applications. The project requirements were to develop a formulation or multiple formulations that have high transparency (85-90%) in the visible region, are hydrophobic (will not opacify with exposure to water vapor or liquid), and have at least 2% resiliency (interpreted as recoverable 2% strain and better than 5% strain to failure in compression). Results from an unrelated project showed that silica aerogels covalently bonded to organic polymers exhibit excellent mechanical properties. At the outset of this project, we believed that such a route is the best to improve mechanical properties. We have applied Design of Experiment (DOE) techniques to optimize formulations including both silica aerogels and organically modified silica aerogels (''Ormosils''). We used these DOE results to optimize formulations around the local/global optimization points. This report documents that we succeeded in developing a number of formulations that meet all of the stated criteria. We successfully developed formulations utilizing a two-step approach where the first step involves acid catalyzed hydrolysis and the second step involves base catalyzed condensation to make the gels. The gels were dried using supercritical CO{sub 2} and we were able to make 1 foot x 1 foot x 0.5 inch panels that met the criteria established.

Jenifer Marchesi Redouane Begag; Je Kyun Lee; Danny Ou; Jong Ho Sonn; George Gould; Wendell Rhine

2004-10-15

140

MARS high-temperature blanket  

SciTech Connect

The MARS high temperature blanket is designed for the dual applications of either high efficiency electricity production or process heat for synthetic fuel production. Other blanket design goals are tritium self-sufficiency, low tritium inventory, more than 40% of the blanket energy extracted at high energy, long lifetime in the neutron environment, no use of reactive liquid metals, minimization of long term activation and use of characterized materials and fabrication techniques. This challenging set of goals has been met with a novel blanket design that uses radial zoning and the unique properties of the lead-lithium eutectic, Pb/sub 83/Li/sub 17/, as a coolant/neutron multiplier/breeder. During the first year of MARS, the blanket design was optimized for electricity production. A reoptimization for the synthetic fuel application is in progress.

Gordon, J.D.; Berwald, D.H.; Flanders, B.A.

1982-12-01

141

Helium cooled Flibe blanket  

SciTech Connect

The blanket design uses a pressure vessel to contain the 50 atmosphere helium gas. Helium cools the first wall and blanket internals. The internals consist of a bed of beryllium balls nominally 1 cm diameter in which neutrons are multiplied and later captured, breeding adequate (even excess) amounts of tritium and releasing energy in exothermic nuclear reactions. Tritium is bred in the molten flibe salt which flows slowly (0.1m/sec) in steel tubes. The salt is kept reducing by periodic reacting with beryllium so the tritium will be in the T/sub 2/ form, however with somewhat enhanced corrosion rate the salt could be kept oxidizing in which case the tritium would be in the TF form. To prevent the tritium from permitting too much into the helium stream, a tungsten coating on the inside of the tubes is proposed. Tritium is removed from the salt and helium by processing both. Because the solubility of tritium in Flibe is so low, there will be a strong driving force for tritium permeation and this places a great burden on a high integrity tungsten permeation barrier. The tritium in the helium is prevented from permeating excessively into the steam system by jacketing the steel steam generator tubes with a 1 mm aluminum jacket. Clearly, tritium containment and barrier development are the most important feasibility issues for this design.

Moir, R.

1984-10-01

142

Structure-property relationships of carbon aerogels  

SciTech Connect

Of the organic reactions in sol-gel polymerizations, the most studied reaction is the aqueous polycondensation of resorcinol with formaldehyde; the resulting crosslinked gels are supercritically dried from CO{sub 2} to give resorcinol-formaldehyde (RF) aerogels. These aerogels can be pyrolyzed to form vitreous carbon monoliths with black color, high porosity, ultrafine cell/pore size, high surface area, and interconnected particles of the organic precursor. The structure and properties of the carbon aerogels depend on R/C (resorcinol/catalyst) ratio of starting solution, pyrolysis temperature, and chemical activation. Each variable is discussed. Carbon aerogels provide an almost ideal electrode material (in double-layer capacitors) owing to low electrical resistivity (<40 mohm-cm), controllable pore size distribution (5--500 {angstrom}), and high volumetric surface areas ({approximately}500 m{sup 2}/cm{sup 3}).

Pekala, R.W.; Alviso, C.T.; Kong, F.M.

1993-12-01

143

Study of multilayer thermal insulation by inverse problems method  

Microsoft Academic Search

The purpose of this paper is to introduce a new method in the research of radiative and thermal properties of materials with further applications in the design of thermal control systems (TCS) of spacecrafts. In this paper the radiative and thermal properties (emissivity and thermal conductance) of a multilayered thermal-insulating blanket (MLI), which is a screen-vacuum thermal insulation as a

O. M. Alifanov; A. V. Nenarokomov; V. M. Gonzalez

2009-01-01

144

Effect of the drying conditions on the microstructure of silica based xerogels and aerogels.  

PubMed

Nanostructured silica based xerogels and aerogels are prepared by sol-gel technology, using methyltrimethoxysilane as precursor. The influence of the drying method and conditions on the microstructure of the obtained materials is investigated, since the drying stage has a critical influence on their porosity. Two types of drying methods were used: atmospheric pressure drying (evaporative), to produce xerogels, and supercritical fluids drying, to obtain aerogels. Although the supercritical fluids drying technique is more expensive and hazardous than the atmospheric pressure drying, it is well known that aerogels are less dense than the xerogels due to less pore shrinkage. However, the ideal situation would be to use atmospheric pressure drying in conditions that minimize the pore collapse. Therefore, in this work, different temperature cycles for atmospheric pressure drying and two heating rates for the supercritical fluids drying are tested to study the gels' shrinkage by analyzing the density and porosity properties of the final materials. The best materials obtained are aerogels dried with the lower heating rate (approximately 80 degrees C/h), since they exhibit very low bulk density (approximately 50 kg/m3), high porosity (95%)-mainly micro and mesopores, high surface area (approximately 500 m2/g), moderate flexibility and a remarkable hydrophobic character (>140 degrees). It was proved that the temperature cycles of atmospheric pressure drying can be tuned to obtain xerogels with properties comparable to those of aerogels, having a bulk density only approximately15 kg/m3 higher. All the synthesized materials fulfill the requirements for application as insulators in Space environments. PMID:22962830

Durães, L; Ochoa, M; Rocha, N; Patrício, R; Duarte, N; Redondo, V; Portugal, A

2012-08-01

145

Structural and acidic characterization of niobia aerogels  

Microsoft Academic Search

A niobia (Nb[sub 2]O[sub 5]) gel was prepared by the hydrolysis and condensation of niobrium pentaethoxide and subsequently dried by supercritical extraction with carbon dioxide to produce an aerogel. The structural and acidic properties of this aerogel heat-treated at different temperatures were characterized by surface area measurements, X-ray diffraction, Raman spectroscopy, n-butylamine titration, pyridine adsorption, and 1-butene isomerization. These results

S. M. Maurer; E. I. Ko

1992-01-01

146

Imaging aerogels at the molecular level  

Microsoft Academic Search

Aerogels are a special class of open-cell foams that have an ultrafine cell\\/pore size (2 g-1), and an ultrastructure composed of interconnected colloidal-like particles or polymeric chains with characteristic dimensions of 10 nm. The purpose of this paper is to directly image a series of resorcinol-formaldehyde (RF) and silica aerogels by high resolution transmission electron microscopy (HRTEM). A new vertical

G. C. Ruben; R. W. Pekala; T. M. Tillotson; L. W. Hrubesh

1992-01-01

147

Microstructural dependence of aerogel mechanical properties  

SciTech Connect

Aerogels are highly porous solids derived from the hypercritical drying of covalently crosslinked gels. SEM, TEM and scattering studies reveal that these materials have an open-cell morphology with a solid matrix composed of interconnected colloidal-like particles. Processing variables and synthetic conditions largely determine the microstructure and morphology. In this study, the structure-mechanical property relationships of silica, resorcinol-formaldehyde, and carbon aerogels are examined. 13 refs., 2 figs.

LeMay, J.D.; Tillotson, T.M.; Hrubesh, L.W.; Pekala, R.W.

1990-04-11

148

Cytochrome C stabilization and immobilization in aerogels.  

PubMed

Sol-gel-derived aerogels are three-dimensional, nanoscale materials that combine large surface areas and high porosities. These traits make them useful for any rate-critical chemical process, particularly sensing or electrochemical applications, once physical or chemical moieties are incorporated into the gels to add their functionality into the ultraporous scaffold. Incorporating biomolecules into aerogels has been challenging due to the inability of most biomolecules to remain structurally intact within the gels during the necessary supercritical fluid processing. However, the heme protein cytochrome c (cyt. c) forms self-organized superstructures around gold (or silver) nanoparticles in buffer that can be encapsulated within silica and processed to form aerogels in which cyt. c retains its characteristic visible absorption. The gold (or silver) nanoparticle-nucleated superstructures protect the majority of the protein from the harsh physicochemical conditions necessary to form an aerogel. The Au?cyt. c superstructures exhibit rapid gas-phase recognition of nitric oxide (NO) within the aerogel matrix, as facilitated by the high-quality pore structure of the aerogel, and remain viable for weeks at room temperature. PMID:20865398

Harper-Leatherman, Amanda S; Wallace, Jean Marie; Rolison, Debra R

2011-01-01

149

Insulation products promote thermal efficiency  

SciTech Connect

The judicious use of thermal insulation products in non-residential buildings can provide a number of advantages including increased energy efficiency, lower first costs (by avoiding overside HVAC systems), improved fire safety and better acoustics. Thermal insulation products are those products which retard the flow of heat energy. Materials include glass, plastics, and organic materials such as wood fibers, vermiculite and perlite. Forms range from the familiar batts and blankets of glass fibers to foamed plastic, rigid boards, losse fill and systems combining two or more products, such as polystyrene boards covered with insulating plaster. The R values of selected insulation materials with a cost/sq. ft. of each material at R 10 are given. Costs cover both the material and installation and may vary depending on local conditions.

Chalmers, R.

1985-04-01

150

Ambient pressure process for preparing aerogel thin films reliquified sols useful in preparing aerogel thin films  

SciTech Connect

A method for preparing aerogel thin films by an ambient-pressure, continuous process is disclosed. The method of this invention obviates the use of an autoclave and is amenable to the formation of thin films by operations such as dip coating. The method is less energy intensive and less dangerous than conventional supercritical aerogel processing techniques.

Brinker, C.J.; Prakash, S.S.

1999-09-07

151

Blanket comparison and selection study. Volume II  

SciTech Connect

This volume contains extensive data for the following chapters: (1) solid breeder tritium recovery, (2) solid breeder blanket designs, (3) alternate blanket concept screening, and (4) safety analysis. The following appendices are also included: (1) blanket design guidelines, (2) power conversion systems, (3) helium-cooled, vanadium alloy structure blanket design, (4) high wall loading study, and (5) molten salt safety studies. (MOW)

Not Available

1983-10-01

152

Synthesis and Properties of Vanadium Oxide Aerogel Films.  

National Technical Information Service (NTIS)

The fine colloid size, high surface area and controllable density of vanadium oxide aerogels make these materials interesting candidates for lithium insertion electrodes. Thin films of vanadium oxide aerogels were prepared using an alkoxide precursor sol ...

H. P. Wong B. Dunn K. Salloux F. Chaput M. W. Breiter

1996-01-01

153

Simplified multilayer insulation pumpdown calculation approach  

Microsoft Academic Search

During launch, or simulated launch, of space vehicles such as NASA's Space Telescope, pressure within Multilayer Blankets (MLI) must decay from atmospheric to minimum effective operational (0.00001 torr) levels rapidly to prevent excessive cooling of insulated hardware during venting time. This evacuation rate is a function of ambient pressure decay rate, number of shields, enclosed volume, venting area, initial temperature,

R. G. Bettini

1983-01-01

154

Heat transfer correlations for multilayer insulation systems  

Microsoft Academic Search

Multilayer insulation (MLI) blankets are extensively used in spacecrafts as lightweight thermal protection systems. Heat transfer analysis of MLI is sometimes too complex to use in practical design applications. Hence, for practical engineering design purposes, it is necessary to have simpler procedures to evaluate the heat transfer rate through MLI. In this paper, four different empirical models for heat transfer

C. K. Krishnaprakas; K. Badari Narayana; Pradip Dutta

2000-01-01

155

Aerogels: A new material for emissive display applications  

SciTech Connect

The remarkable optical and electronic properties of doped and undoped silica aerogels establish their utility as unique, multifunctional host materials for fluorescent dyes and other luminescent materials for display and imaging applications. We present results on the photoluminescence and absorption of undoped silica aerogels and aerogels doped with Er{sup 3+}, rhodamine 6G (R6G), and fluorescein. We also demonstrate evidence of Fowler-Nordheim tunneling of electrons in aerogels. 4 refs., 10 figs.

Glauser, S.A.C. [California Univ., Davis, CA (United States); Lee, H.W.H. [Lawrence Livermore National Lab., CA (United States)

1997-03-01

156

Synthesis and magnetic properties of iron oxide silica aerogel nanocomposites  

Microsoft Academic Search

Iron oxide silica nanocomposite aerogels were produced by sol gel procedure followed by the hypercritical evaporation of the solvent. Aerogels hosting maghemite were synthesized from the precursors TEOS and TMOS. Mean oxide particle size seems to be strongly influenced by the solvent. The magnetic properties of the iron oxide particles hosted in silica aerogeles pores were studied by means of

M. B. Fernández van Raap; F. H. Sanchez; A. G. Leyva; M. L. Japas; E. Cabanillas; H. Troiani

2007-01-01

157

Carbon aerogels: An update on structure, properties, and applications  

SciTech Connect

Aerogels are unique porous materials whose composition, structure, and properties can be controlled at the nanometer scale. This paper examines the synthesis of organic aerogels and their carbonized derivatives. Carbon aerogels have low electrical resistivity, high surface area, and a tunable pore size. These materials are finding applications as electrodes in double layer capacitors.

Pekala, R.W.; Mayer, S.T.; Kaschmitter, J.L.; Kong, F.M.

1993-07-01

158

Effective emittance measurements on clamshell-wrapped multi-layer insulation for half inch tubing  

NASA Astrophysics Data System (ADS)

The three clamshell-wrapped multi-layer insulation (MLI) blankets for Space Station external fuel lines have been subjected to effective emittance measurements. Tube target temperatures were of the order of 110 to -40 F. While blanket no. 1 was modeled after that currently used on the Space Shuttle Orbiter, the no. and no. 3 blankets were designed to reduce heat leakage through minimization of EVA flap material.

Stobb, C. A.

1993-07-01

159

Analysis of ER string test thermally instrumented interconnect 80-K MLI blanket.  

National Technical Information Service (NTIS)

An 80-K Multi Layer Insulation (MLI) blanket in the interconnect region between magnets DD0019 and DD0027 in the Fermi National Accelerator Laboratory (FNAL) ER string was instrumented with temperature sensors to obtain the steady-state temperature gradie...

E. Daly R. Pletzer

1992-01-01

160

High resolution transmission electron microscopy of melamine-formaldehyde aerogels and silica aerogels  

SciTech Connect

The goal of the high resolution transmission electron microscopy (HRTEM) was to image the structure of two tetramethyl orthosilicate (TMOS) and two melamine-formaldehyde (MF) aerogels at the single polymer chain level{sup 1,2}. With this level of structural resolution we hoped to interrelate each aerogel's structure with its physical properties and its method of synthesis. Conventional single-step base catalysed TMOS aerogels show strings of spheroidal particles linked together with minimal necking. The spheroidal particles range from 86--132 {Angstrom} and average 113{plus minus}10 {Angstrom} in diameter{sup 2}. In contrast the TMOS aerogels reported on here were made by a two step method. After extended silica chains are grown in solution under acidic conditions with a substoichiometric amount of water, the reaction is stopped and the methanol hydrolysed from TMOS is removed. Then base catalysis and additional water are added to cause gel formation is a nonalcoholic solvent. The MF aerogels were prepared for HRTEM by fracturing them on a stereo microscope stage with razor knife so that fractured pieces with smooth flat surfaces could be selected for platinum-carbon replication. The two silica (TMOS) aerogels were both transparent and difficult to see. These aerogels were fractured on a stereo microscope stage with tweezers. 6 refs., 4 figs.

Ruben, G.C. (Dartmouth Coll., Hanover, NH (United States). Dept. of Biological Sciences)

1991-09-01

161

Venting through multiple-layer insulation on Space Station Freedom. II - Ascent rate pressure chamber testing  

Microsoft Academic Search

A test was conducted to determine the venting characteristics of the multiple-layer insulation (MLI) to be installed on the Space Station Freedom (SSF). A full MLI blanket with inter-blanket joints was installed onto a model of a section of the SSF pressure wall, support structure, and debris shield. Data were taken from this test and were used to predict the

Jeffrey B. Sharp; Alan Buitekant; John F. Fay; Jon B. Holladay

1993-01-01

162

The aerocapacitor: A carbon aerogel based supercapacitor  

SciTech Connect

During the 1980's, a wide variety of carbon foams, formed by the pyrolysis of polymeric foams, were developed at several Department of Energy Laboratories. These foams are known for their monolithic structure and the ability to tailor their critical parameters (e.g. porosity, density). Lawrence Livermore National Laboratory (LLNL) exclusively developed a unique type of carbon foam, known as carbon aerogels. Carbon aerogels are a special class of open-cell foams with (1) homogeneous ultrafine particle and pore size, (2) very large useful surface area per unit volume, and (3) monolithic structure, that yields (4) excellent electrical conductivity due to the intimate connection of the particles. We have applied carbon aerogels to make an Aerocapacitor''; a high power- and energy-density electrochemical double layer capacitor (EDLC) that uses carbon aerogels as electrodes. Carbon aerogel surface areas range from about 100 to 700 m[sup 2]/cc (as measured by BET analysis), with bulk densities of 0.05 to 1.0 g/cm[sup 3] and their morphology allows stored energy to be released rapidly, resulting in high power-densities.

Mayer, S.T.; Pekala, R.W.; Kaschmitter, J.L.

1992-12-01

163

The aerocapacitor: A carbon aerogel based supercapacitor  

SciTech Connect

During the 1980`s, a wide variety of carbon foams, formed by the pyrolysis of polymeric foams, were developed at several Department of Energy Laboratories. These foams are known for their monolithic structure and the ability to tailor their critical parameters (e.g. porosity, density). Lawrence Livermore National Laboratory (LLNL) exclusively developed a unique type of carbon foam, known as carbon aerogels. Carbon aerogels are a special class of open-cell foams with (1) homogeneous ultrafine particle and pore size, (2) very large useful surface area per unit volume, and (3) monolithic structure, that yields (4) excellent electrical conductivity due to the intimate connection of the particles. We have applied carbon aerogels to make an ``Aerocapacitor``; a high power- and energy-density electrochemical double layer capacitor (EDLC) that uses carbon aerogels as electrodes. Carbon aerogel surface areas range from about 100 to 700 m{sup 2}/cc (as measured by BET analysis), with bulk densities of 0.05 to 1.0 g/cm{sup 3} and their morphology allows stored energy to be released rapidly, resulting in high power-densities.

Mayer, S.T.; Pekala, R.W.; Kaschmitter, J.L.

1992-12-01

164

An Overview of US ITER Test Blanket Module Program  

SciTech Connect

A testing strategy and corresponding test plan have been presented for the two proposed US candidate breeder blankets: 1) a helium-cooled solid breeder concept with ferritic steel structure and Be neutron multiplier, but without a fully independent TBM, and 2) a dual-coolant helium-cooled ferritic steel structure with self-cooled LiPb breeding zone that uses a flow channel insert as MHD and thermal insulator. Example test module designs, and configuration choices for each line of ITER TBM are shown and discussed in the paper. In addition, near-term R&D items for decision-making on testing of both solid breeder and dual-coolant PbLi liquid breeder blanket concepts in ITER are identified.

Ying, A.; Abdou, Mohamed A.; Wong, Clement; Malang, S.; Morley, Neil B.; Sawan, M.; Merrill, Brad; Sze, Dai Kai; Kurtz, Richard J.; Willms, Scott; Ulrickson, Mike; Zinkle, Steven J.

2006-01-01

165

Water extractable arabinoxylan aerogels prepared by supercritical CO2 drying.  

PubMed

Water extractable arabinoxylan (WEAX) aerogels were prepared by extracting the solvent from the alcogels (WEAX hydrogels with an alcohol as the solvent) with carbon dioxide under supercritical conditions. WEAX aerogels were characterized using scanning electron microscopy and adsorption and desorption nitrogen isotherms. The micrographs indicate a heterogeneous porous network structure in WEAX aerogel. Adsorption/desorption nitrogen isotherms of this material were type IV, which confirm that this material possess a mesoporous structure. WEAX aerogels rehydration capability was evaluated and the water absorption mechanism was determined. The WEAX aerogels water absorption mechanism was non-Fickian (n = 0.54). PMID:23673527

Marquez-Escalante, Jorge; Carvajal-Millan, Elizabeth; Miki-Yoshida, Mario; Alvarez-Contreras, Lorena; Toledo-Guillén, Alma Rosa; Lizardi-Mendoza, Jaime; Rascón-Chu, Agustín

2013-05-14

166

Thermal performance of various multilayer insulation systems below 80K  

Microsoft Academic Search

The SSC collider dipole cryostat consists of a vacuum shell operating at room temperature, two thermal shields operating near 80K and 20K respectively, and the superconducting magnet assembly operating near 4K. The cryostat design incorporates multilayer insulation (MLI) blankets to limit radiant heat transfer into the 80K and 20K thermal shields. Also, an MLI blanket is used to impede heat

W. N. Boroski; T. H. Nicol; C. J. Schoo

1992-01-01

167

Structural and acidic characterization of niobia aerogels  

SciTech Connect

A niobia (Nb[sub 2]O[sub 5]) gel was prepared by the hydrolysis and condensation of niobrium pentaethoxide and subsequently dried by supercritical extraction with carbon dioxide to produce an aerogel. The structural and acidic properties of this aerogel heat-treated at different temperatures were characterized by surface area measurements, X-ray diffraction, Raman spectroscopy, n-butylamine titration, pyridine adsorption, and 1-butene isomerization. These results were then compared to those of a niobia xerogel, a precipitated niobia, and a commerical niobic acid. The synthetic route to produce the aerogel was found to stabilize a porous network consisting of NbO[sub 6] octahedra with Nb [double bond] O bonds which gave rise to strong Lewis acid sites. Steady-state activity and selectivity data of 1-butene isomerization suggested that all niobia samples possessed comparable Broensted acidity.

Maurer, S.M.; Ko, E.I. (Carnegie Mellon Univ., Pittsburgh, PA (United States))

1992-05-01

168

Aerogel Algorithm for Shrapnel Penetration Experiments  

NASA Astrophysics Data System (ADS)

To aid in assessing shrapnel produced by laser-irradiated targets, we have performed shrapnel collection ``BB gun'' experiments in aerogel and have developed a simple analytical model for deceleration of the shrapnel particles in the aerogel. The model is similar in approach to that of Anderson and Ahrens (J. Geophys. Res., 99 El, 2063-2071, Jan. 1994) and accounts for drag, aerogel compaction heating, and the velocity threshold for shrapnel ablation due to conductive heating. Model predictions are correlated with the BB gun results at impact velocities up to a few hundred m/s and with NASA data for impact velocities up to 6 km/s. The model shows promising agreement with the data and will be used to plan and interpret future experiments.

Tokheim, R. E.; Erlich, D. C.; Curran, D. R.; Tobin, M.; Eder, D.

2004-07-01

169

Ambient-pressure silica aerogel films  

SciTech Connect

Very highly porous (aerogel) silica films with refractive index in the range 1.006--1.05 (equivalent porosity 98.5--88%) were prepared by an ambient-pressure process. It was shown earlier using in situ ellipsometric imaging that the high porosity of these films was mainly attributable to the dilation or `springback` of the film during the final stage of drying. This finding was irrefutably reconfirmed by visually observing a `springback` of >500% using environmental scanning electron microscopy (ESEM). Ellipsometry and ESEM also established the near cent per cent reversibility of aerogel film deformation during solvent intake and drying. Film thickness profile measurements (near the drying line) for the aerogel, xerogel and pure solvent cases are presented from imaging ellipsometry. The thickness of these films (crack-free) were controlled in the range 0.1-3.5 {mu}m independent of refractive index.

Prakash, S.S. [New Mexico Univ., Albuquerque, NM (United States); Brinker, C.J. [New Mexico Univ., Albuquerque, NM (United States)]|[Sandia National Labs., Albuquerque, NM (United States); Hurd, A.J. [Sandia National Labs., Albuquerque, NM (United States)

1994-12-31

170

Status of fusion reactor blanket design  

SciTech Connect

The recent Blanket Comparison and Selection Study (BCSS), which was a comprehensive evaluation of fusion reactor blanket design and the status of blanket technology, serves as an excellent basis for further development of blanket technology. This study provided an evaluation of over 130 blanket concepts for the reference case of electric power producing, DT fueled reactors in both Tokamak and Tandem Mirror (TMR) configurations. Based on a specific set of reactor operating parameters, the current understanding of materials and blanket technology, and a uniform evaluation methodology developed as part of the study, a limited number of concepts were identified that offer the greatest potential for making fusion an attractive energy source.

Smith, D.L.; Sze, D.K.

1986-02-01

171

Transport of liquids using superhydrophobic aerogels  

Microsoft Academic Search

The experimental results of the studies on the transportation of water droplets on a superhydrophobic silica aerogel-powder-coated surface are reported. The superhydrophobic silica aerogels were prepared using sol–gel processing of methyltrimethoxysilane (MTMS) precursor, methanol (MeOH) solvent, and base (NH4OH)-catalyzed water followed by supercritical drying using methanol solvent. The molar ratio of NH4OH\\/MTMS, H2O\\/MTMS, and MeOH\\/MTMS were varied from 1.7×10?1 to

A. Venkateswara Rao; Manish M. Kulkarni; Sharad D. Bhagat

2005-01-01

172

Incorporation of noble metals into aerogels  

DOEpatents

Aerogels or xerogels containing atomically dispersed noble metals for applications such environmental remediation. New noble metal precursors, such as Pt--Si or Pd(Si--P).sub.2, have been created to bridge the incompatibility between noble metals and oxygen, followed by their incorporation into the aerogel or xerogel through sol-gel chemistry and processing. Applications include oxidation of hydrocarbons and reduction of nitrogen oxide species, complete oxidation of volatile organic carbon species, oxidative membranes for photocatalysis and partial oxidation for synthetic applications.

Hair, Lucy M. (Livermore, CA); Sanner, Robert D. (Livermore, CA); Coronado, Paul R. (Livermore, CA)

1998-01-01

173

Simplified multilayer insulation pumpdown calculation approach  

NASA Astrophysics Data System (ADS)

During launch, or simulated launch, of space vehicles such as NASA's Space Telescope, pressure within Multilayer Blankets (MLI) must decay from atmospheric to minimum effective operational (0.00001 torr) levels rapidly to prevent excessive cooling of insulated hardware during venting time. This evacuation rate is a function of ambient pressure decay rate, number of shields, enclosed volume, venting area, initial temperature, and trapped gas. A simplified computer simulation that estimates blanket internal pressure during an isentropic evacuation as a function of the above variables is presented. Analytical predictions are compared to test data to confirm the reasonableness of this approach.

Bettini, R. G.

1983-04-01

174

MHD pressure drops and thermal hydraulic analysis for the ITER breeding blanket design  

NASA Astrophysics Data System (ADS)

The breeding blanket design of the International Thermonuclear Experimental Reactor (ITER) is a self-cooled liquid lithium system with a vanadium structure. Electrical insulation of the coolant channel surfaces from the liquid metal is required to reduce the magnetohydrodynamic (MHD) pressure to less than 1 MPa. Insulation is provided by AIN coating at the channel surfaces in contact with lithium. MHD pressure drop and thermal hydraulic analysis of the blanket design is carried out subject to pressure, temperature, and stress considerations. Design windows relating the lithium flow velocity, MHD pressure, and structural temperature are formulated. The requirements of the insulator coating and characterization of the coating effectiveness are presented. Effects on the MHD pressure drop due to uniform cracks through the coating layer is also analyzed.

Hua, Thanh Q.; Gohar, Y.

1994-06-01

175

Methyltrimethoxysilane based flexible silica aerogels for oil absorption applications  

NASA Astrophysics Data System (ADS)

The experimental results on the synthesis of flexible and superhydrophobic silica aerogels using methyltrimethoxysilane (MTMS) precursor by a two-step (acid-base) sol-gel process followed by the supercritical drying are reported. The effects of various sol-gel parameters on the flexibility of the aerogels have been investigated. The aerogels of different densities were obtained by varying the molar ratio of MeOH/MTMS(S) from 14 to 35, with lower densities for larger S values. It has been observed that the Young's modulus (Y) decreased from 14.11 × 104 to 3.43×104 N/m2 with the decrease in the density of the aerogels from 100 to 40 kg/m3. Simultaneously, the aerogels are superhydrophobic with a contact angle as high as 169°. The superhydrophobic aerogels are thermally stable up to a temperature of 463 K, above which they become hydrophilic. The aerogels have been characterized by bulk density, percentage volume shrinkage, and porosity measurements. The microstructures of the aerogels have been studied using the transmission electron microscopy (TEM). The Young's modulus of the aerogels has been determined by an uniaxial compression test. The variation of physical properties of the aerogels has been explained by taking into consideration the hydrolysis, condensation reactions, the resulting colloidal clusters and their network formation.

Kavale, Mahendra S.; Mahadik, D. B.; Parale, V. G.; Rao, A. Venkateswara; Wagh, P. B.; Gupta, S. C.

2012-06-01

176

Morphology-controlled graphene aerogel for energy storage  

NASA Astrophysics Data System (ADS)

The development of new anode/cathode materials with highly conductive, non-corrosive, high specific surface area and high porosity for energy storage devices is highly desirable. Graphene aerogels has been focused emergently recently due to novel properties of the graphene. However, the aerogel-based application performance strongly depends on the morphology and structure of the graphene aerogels. The graphene aerogels with low-density have thinner struts, a different distribution of particle sizes, and less internal connectivity. This, in turn, changes the way the material can transport electric charge. As a result, the highest surface area graphene aerogels end up having the worst electrical conductivity, and the most conductive graphene aerogels have lowest surface areas. So the best designs of the developed graphene aerogel nanostructures in terms of pore size, porosity, density and mechanical properties for energy storage devices are essential. In this work, we develop a new fabrication method of graphene aerogels with well-controlled morphology and high electrical conductivity from graphene oxide through the supercritical drying process. The morphology and electrical conductivity of the graphene aerogels are controlled by the precursor contents and the synthesis conditions. The experimental results are very useful for experimentalists deciding the best graphene aerogel nanostructures for their needs.

Truong Nguyen, Son; Tien Nguyen, Hoa; Duong, Hai Minh

2012-02-01

177

Control of nanoparticle aggregation in aerogel hosts  

Microsoft Academic Search

Plasmonic aerogel containing 50nm gold nanoparticles is made using a modified 2-step method that maintains control over the gel time while preventing nanoparticle aggregation. Strong narrow surface plasmon resonances verify that the nanoparticles are well dispersed within the silica matrix, and enable applications in sensing, SERS, nonlinear optics or plasmonic gain. Discrepancies between measured and simulated resonance wavelengths are attributed

M. D. W. Grogan; S. C. Heck; L. M. Xiao; R. England; S. A. Maier; T. A. Birks

178

Chemical Analyses of Silicon Aerogel Samples.  

National Technical Information Service (NTIS)

After five years of operating, two Aerogel counters: A1 and A2, taking data in Hall A at Jefferson Lab, suffered a loss of performance. In this note possible causes of degradation have been studied. In particular, various chemical and physical analyses ha...

F. Palmisano R. De Leo S. Marrone T. van der Werf

2008-01-01

179

Eureka Aerogel Capture of Meteoroids in Space.  

National Technical Information Service (NTIS)

Light gas gun studies have shown that 6 km/s solid mineral and glass test particles can be successively captured in 0.05 g cm(exp -3) aerogel without severe heating or fragmentation. In spite of this work, there has been uncertainty in the performance of ...

D. E. Brownlee F. Horz L. Hrubsch J. A. M. Mcdonnell P. Tsou

1994-01-01

180

Manufacturing complex silica aerogel target components  

SciTech Connect

Aerogel is a material used in numerous components in High Energy Density Physics targets. In the past these components were molded into the proper shapes. Artifacts left in the parts from the molding process, such as contour irregularities from shrinkage and density gradients caused by the skin, have caused LANL to pursue machining as a way to make the components.

Defriend Obrey, Kimberly Ann [Los Alamos National Laboratory; Day, Robert D [Los Alamos National Laboratory; Espinoza, Brent F [Los Alamos National Laboratory; Hatch, Doug [Los Alamos National Laboratory; Patterson, Brian M [Los Alamos National Laboratory; Feng, Shihai [Los Alamos National Laboratory

2008-01-01

181

Multiplier, moderator, and reflector materials for lithium-vanadium fusion blankets.  

SciTech Connect

The self-cooled lithium-vanadium fusion blanket concept has several attractive operational and environmental features. In this concept, liquid lithium works as the tritium breeder and coolant to alleviate issues of coolant breeder compatibility and reactivity. Vanadium alloy (V-4Cr-4Ti) is used as the structural material because of its superior performance relative to other alloys for this application. However, this concept has poor attenuation characteristics and energy multiplication for the DT neutrons. An advanced self-cooled lithium-vanadium fusion blanket concept has been developed to eliminate these drawbacks while maintaining all the attractive features of the conventional concept. An electrical insulator coating for the coolant channels, spectral shifter (multiplier, and moderator) and reflector were utilized in the blanket design to enhance the blanket performance. In addition, the blanket was designed to have the capability to operate at high loading conditions of 2 MW/m{sup 2} surface heat flux and 10 MW/m{sup 2} neutron wall loading. This paper assesses the spectral shifter and the reflector materials and it defines the technological requirements of this advanced blanket concept.

Gohar, Y.; Smith, D. L.

1999-10-07

182

Desalination with carbon aerogel electrodes. Revision 1  

SciTech Connect

Electrically regenerated electrosorption process (carbon aerogel CDI) was developed by LLNL for continuously removing ionic impurities from aqueous streams. A salt solution flows in a channel formed by numerous pairs of parallel carbon aerogel electrodes. Each electrode has a very high BET surface area (2-5.4x10{sup 6}ft{sup 2}lb{sup -1} or 400-1100 m{sup 2}g{sup -1}) and very low electrical resistivity ({le}40 m{Omega}). Ions are removed from the electrolyte by the electric field and electrosorbed onto the carbon aerogel. It is concluded that carbon aerogel CDI may be an energy-efficient alternative to electrodialysis and reverse osmosis for desalination of brackish water ({le}5000 ppM). The intrinsic energy required by this process is about QV/2, where Q is the stored electrical charge and V is the voltage between the electrodes, plus losses. Estimated requirement for desalination of a 2000 ppM feed is -0.53-2.5 Wh/gal{sup -1} (0.5-2.4 kJ L{sup -1}), depending on voltage, flow rate, cell dimensions, aerogel density, recovery ratio, etc. This assumes that 50-70% of the stored electrical energy is reclaimed during regeneration (electrical discharge). Though the energy requirement for desalination of sea water is also low, this application will be much more difficult. Additional work will be required for desalination of streams that contain more than 5000 ppM total dissolved solids (2000 ppM will require electrochemical cells with extremely tight, demanding tolerances). At this present time, the process is best suited for streams with dilute impurities, as recently demonstrated during a field test at LLNL Treatment Facility C.

Farmer, J.C.; Richardson, J.H.; Fix, D.V. [Lawrence Livermore National Lab., CA (United States); Thomson, S.L.; May, S.C. [Bechtel National, Inc., San Francisco, CA (United States)

1996-12-04

183

Cryogenic insulation  

Microsoft Academic Search

Midwesco Enterprise, Inc, has developed an improved insulator for use with LNG pipelines that practically satisfies the theoretical promise of a satisfactory insulator, is relatively inexpensive, does not require periodic reevacuation (as does vacuum-type insulation), and offers a coefficient of thermal expension sufficiently low to prevent cracking at the cold face next to the line (unlike polyurethane foam). This new

Hallwood

1974-01-01

184

Processing and characterization of high porosity aerogel films  

SciTech Connect

Aerogels are highly porous solids having unique morphology among materials because both the pores and particles making up the material have sizes less than wavelengths of visible light. Such a unique morphology modifies the normal molecular transport mechanisms within the material, resulting in exceptional thermal, acoustical, mechanical, and electrical properties. For example, aerogels have the lowest measured thermal conductivity and dielectric constant for any solid material. Special methods are required to make aerogel films with high porosity. In this paper, we discuss the special conditions needed to fabricate aerogel films having porosities greater than 75% and we describe methods of processing inorganic aerogel films having controllable thicknesses in the range 0.5 to 200 micrometers. We report methods and results of characterizing the films including thickness, refractive index, density (porosity), and dielectric constant. We also discuss results of metallization and patterning on the aerogel films for applications involving microminiature electronics and thermal detectors.

Hrubesh, L.W.; Poco, J.F.

1994-11-22

185

Non-silica aerogels as hypervelocity particle capture materials  

NASA Astrophysics Data System (ADS)

The Stardust sample return mission to the comet Wild 2 used silica aerogel as the principal cometary and interstellar particle capture and return medium. However, since both cometary dust and interstellar grains are composed largely of silica, using a silica collector complicates the science that can be accomplished with these particles. The use of non-silica aerogel in future extra-terrestrial particle capture and return missions would expand the scientific value of these missions. Alumina, titania, germania, zirconia, tin oxide, and resorcinol/formaldehyde aerogels were produced and impact tested with 20, 50, and 100?m glass microspheres to determine the suitability of different non-silica aerogels as hypervelocity particle capture mediums. It was found that non-silica aerogels do perform as efficient hypervelocity capture mediums, with alumina, zirconia, and resorcinol/formaldehyde aerogels proving to be the best of the materials tested.

Jones, Steven M.

2010-01-01

186

Effect of Ultra Violet Radiation on Surface Properties: Comparison of RTV 655 and Silica--Based Aerogels  

NASA Astrophysics Data System (ADS)

The broad spectrum of ultra violet (UV) radiation causes material property changes such as chalkiness, brittleness, color change, and ultimately complete mechanical failure. UV radiation is also known to modify the surface charge state of insulators. These effects are intensified for materials used in space exploration due to the lack of an atmosphere. In this work, we compare the radiation response and the material properties of RTV 655 (existing calibration targets material on Phoenix Mars Lander) and silica-based aerogels. The extreme light-weight and ability to color-code aerogels makes this material a candidate for the next generation of calibration targets. The radiation response of both materials will be studied using Kelvin Probe, UV-VIS spectrophotometry, and ESR techniques.

Sinden-Redding, Mackenzie; Sabri, Firouzeh

2009-11-01

187

Synthesis and magnetic properties of iron oxide silica aerogel nanocomposites  

NASA Astrophysics Data System (ADS)

Iron oxide silica nanocomposite aerogels were produced by sol gel procedure followed by the hypercritical evaporation of the solvent. Aerogels hosting maghemite were synthesized from the precursors TEOS and TMOS. Mean oxide particle size seems to be strongly influenced by the solvent. The magnetic properties of the iron oxide particles hosted in silica aerogeles pores were studied by means of magnetometry and AC susceptometry. Interrelation between synthesis parameters, structure and magnetic behavior is discussed.

Fernández van Raap, M. B.; Sanchez, F. H.; Leyva, A. G.; Japas, M. L.; Cabanillas, E.; Troiani, H.

2007-09-01

188

Functionalisation and chemical characterisation of cellulose-derived carbon aerogels  

Microsoft Academic Search

A series of nitrogen- and oxygen-functionalised carbon aerogels was produced from a carbon aerogel derived from cellulose acetate. Samples were oxidised by H2O2 or HNO3 and\\/or enriched in nitrogen by reaction with gaseous ammonia or co-heating of the carbon aerogel and melamine. Porosity variations and morphology were monitored using N2 adsorption and helium pycnometry. The surface chemistry was characterised by

Bartosz Grzyb; Claudia Hildenbrand; Sandrine Berthon-Fabry; Dominique Bégin; Nathalie Job; Arnaud Rigacci; Patrick Achard

2010-01-01

189

Energy loss and impact cratering in aerogels: theory and experiment  

Microsoft Academic Search

Aerogel collectors have been deployed in low-Earth orbit to collect orbital debris and micrometeorites. An array of silica aerogel collectors is currently en-route back to Earth following an encounter with the Comet Wild-2 on board the Stardust spacecraft. Stardust is returning, for laboratory analysis, cometary and interstellar dust grains which impacted into the aerogel collectors at hypervelocities. While the morphology

Gerardo Domínguez; Andrew J. Westphal; Steven M. Jones; Mark L. F. Phillips

2004-01-01

190

Magnetic and Mössbauer spectroscopy studies of nanocrystalline iron oxide aerogels  

NASA Astrophysics Data System (ADS)

A sol-gel synthesis was used to produce iron oxide aerogels. These nanocrystalline aerogels have a pore-solid structure similar to silica aerogels but are composed entirely of iron oxides. Mössbauer experiments and x-ray diffraction showed that the as-prepared aerogel is an amorphous or poorly crystalline iron oxide, which crystallized as a partially oxidized magnetite during heating in argon. After further heat treatment in air, the nanocrystallites are fully converted to maghemite. The particles are superparamagnetic at high temperatures, but the magnetic properties are strongly influenced by magnetic interactions between the particles at lower temperatures.

Carpenter, E. E.; Long, J. W.; Rolison, D. R.; Logan, M. S.; Pettigrew, K.; Stroud, R. M.; Kuhn, L. Theil; Hansen, B. Rosendahl; Mørup, S.

2006-04-01

191

Purging of a tank-mounted multilayer insulation system by gas diffusion  

Microsoft Academic Search

The investigation was conducted on a multilayer insulation (MLI) system mounted on a spherical liquid hydrogen propellant tank. The MLI consisted of two blankets of insulation each containing 15 double-aluminized Mylar radiation shields separated by double silk net spacers. The gaseous nitrogen initially contained within the MLI system and vacuum chamber was purged with gaseous helium introduced both underneath the

I. E. Sumner

1978-01-01

192

Aerogel Keystones: Extraction Of Complete Hypervelocity Impact Events From Aerogel Collectors  

SciTech Connect

In January 2006, the Stardust mission will return the first samples from a solid solar-system body since Apollo, and the first samples of contemporary interstellar dust ever collected. Although sophisticated laboratory instruments exist for the analysis of Stardust samples, techniques for the recovery of particles and particle residues from aerogel collectors remain primitive. Here we describe our recent progress in developing techniques for extracting small volumes of aerogel, which we have called ''keystones,'' which completely contain particle impacts but minimize the damage to the surrounding aerogel collector. These keystones can be fixed to custom-designed micromachined silicon fixtures (so-called ''microforklifts''). In this configuration the samples are self-supporting, which can be advantageous in situations in which interference from a supporting substrate is undesirable. The keystones may also be extracted and placed onto a substrate without a fixture. We have also demonstrated the capability of homologously crushing these unmounted keystones for analysis techniques which demand flat samples.

Westphal, A J; Snead, C; Butterworth, A; Graham, G A; Bradley, J; Bajt, S; Grant, P G; Bench, G; Brennan, S; Piannetta, P

2003-11-07

193

Magnetic hydrophobic nanocomposites: Silica aerogel/maghemite  

NASA Astrophysics Data System (ADS)

Magnetic hydrophobic aerogels (MHA) in the form of nanocomposites of silica and maghemite (?-Fe2O3) were prepared by one step sol-gel procedure followed by supercritical solvent extraction. Silica alcogels were obtained from TEOS, MTMS, methanol and H2O, and Fe(III) nitrate as magnetic precursor. The hydrophobic property was achieved using the methytrimethoxysilane (MTMS) as co-precursor for surface modification. The so produced nanocomposite aerogels are monolithic, hydrophobic and magnetic. The interconnected porous structure hosts ˜6 nm size ?-Fe2O3 particles, has a mean pore diameter of 5 nm, and a specific surface area (SSA) of 698 m²/g. Medium range structure of MHA is determined by SAXS, which displays the typical fractal power law behavior with primary particle radius of ˜1 nm. Magnetic properties of the nanoparticle ensembles hosted in them are studied by means of dc-magnetometry.

Mendoza Zélis, P.; Fernández van Raap, M. B.; Socolovsky, L. M.; Leyva, A. G.; Sánchez, F. H.

2012-08-01

194

Evaluation of Fire Test Methods for Aircraft Thermal Acoustical Insulation  

Microsoft Academic Search

Round robin flammability testing was performed by eight laboratories on thermal acoustical insulation blankets and films used asinsulation coverings. Test samples were subjected to vertical Bunsen burner testing and cotton swab testing. The test dataindicated that the cotton swab test produced consistent test results, whereas the vertical flammability test did not.17. Key WordsThermal acoustical insulation, Cotton swab test, VerticalBunsen burner

Patricia Cahill

1997-01-01

195

Directory of certified insulation material. Sorted by type and manufacturer  

SciTech Connect

Insulation materials that have been certified as complying with the regulations that became effective September 22, 1981 are identified in the directory. Six physical forms of insulation are covered: board; foil; foam and spray; blanket; loose fill; and water heater kits, duct, and pipe wrap. Information on the manufacturer and brand name; material, type, facings; primary use, usage exposure, vapor barrier; labeled product thickness, and labeled thermal performance is given. (MCW)

Not Available

1982-03-01

196

Method for making monolithic metal oxide aerogels  

DOEpatents

Transparent, monolithic metal oxide aerogels of varying densities are produced using a method in which a metal alkoxide solution and a catalyst solution are prepared separately and reacted. The resulting hydrolyzed-condensed colloidal solution is gelled, and the wet gel is contained within a sealed, but gas permeable, containment vessel during supercritical extraction of the solvent. The containment vessel is enclosed within an aqueous atmosphere that is above the supercritical temperature and pressure of the solvent of the metal alkoxide solution.

Coronado, Paul R. (Livermore, CA)

1999-01-01

197

Subcritical crack growth in silica aerogel  

Microsoft Academic Search

The sub-critical crack growth domain in hydrophilic silica aerogel was studied using the Double-Cleavage-Drilled-Compression test (DCDC). The effect of temperature and water vapor content on the crack growth rate is measured. The experiments are carried out between 295 and 383 K with relative air moisture ranging from 5% to 80% Rh. Like dense silica, crack growth velocities were found to

F. Despetis; P. Etienne; S. Etiennecalas

2004-01-01

198

Use of silica aerogels in Cherenkov counters  

Microsoft Academic Search

Silica aerogel is widely used as a radiator for Cherenkov detectors. It is a highly porous, low-density, and transparent substance\\u000a with refractive index n ranging between the values of n n ? 1.3 for condensed phases. The review is devoted to the consideration of various factors affecting the identification of\\u000a particles in Cherenkov counters: the chromatic aberration, the number of

Yu. N. Kharzheev

2008-01-01

199

Positron and positronium studies of silica aerogel  

NASA Astrophysics Data System (ADS)

Variable-energy positron annihilation spectroscopy (VEPAS) has been used to probe the structure of gold nanoparticles suspended in a silica aerogel matrix by measuring the annihilation parameters S and W, and the ortho-positronium (o-Ps) fraction parameter F, as a function of incident positron energy. Correction methods have been developed to improve the sensitivity of F by removing background contributions to the number of recorded o-Ps annihilation events. Charging effects have also been observed and investigated.

Edwardson, C. J.; Grogan, M. D. W.; Birks, T. A.; Coleman, P. G.

2011-01-01

200

Structure and performance of carbon aerogel electrodes  

SciTech Connect

The chemistry and physics of small clusters of atoms (1--100 nm) has received considerable attention in recent years because these assemblies often have properties between the molecular and bulk solid-state limits. The different properties can be explained in terms of the large fraction of atoms that are at the surface of a cluster as compared to the interior. Although the synthesis and properties of metal and. semiconductor clusters, metallocarbohedrenes, fullerenes, and nanotubes are the subject of extensive investigations, little attention has been paid to cluster-assembled porous materials. This oversight is of particular interest to us since we believe that aerogels are one of the few monolithic materials presently available where the benefits of cluster assembly can be demonstrated. In particular, the unique optical, thermal, acoustic, mechanical, and electrical properties of aerogels are directly related to their nanostructure, which is composed of interconnected particles (3--30 nm) with small interstitial pores (< 50 nm). This structure leads to extremely high surface areas (400--1100 m{sup 2}/g) with a large fraction of the atoms covering the surface of the interconnected particles. As a result of these structural features, carbon aerogels are finding applications as electrodes in supercapacitors with high energy and power densities.

Pekala, R.W.; Mayer, S.T.; Poco, J.F.; Kaschmitter, J.L.

1994-03-01

201

Effect of uni-axial loading on the nanostructure of silica aerogels  

Microsoft Academic Search

Aerogels are unique materials offering a combination of remarkable properties that make them useful in a wide range of applications. However, aerogel materials can be difficult to work with because they are fragile. The intent of the work presented here was to study the relationship between axial loading and pore structure in aerogel material. Silica aerogel samples with a bulk

Ondrej Nikel; Ann M. Anderson; Mary K. Carroll; William D. Keat

2011-01-01

202

Present Status of ITER Test Blanket Development  

NASA Astrophysics Data System (ADS)

As one of the engineering test programs in ITER, the test blanket program, which utilizes ITER as a test bed to develop breeding blanket systems for fusion DEMO plants, has been planned and advanced. The Test Blanket Working Group (TBWG) has been organized to review and coordinate test programs on Test Blanket Modules(TBM). Five breeding blanket concepts have been proposed and discussed in the TBWG, and Japan is participating in the development of all of these concepts. This paper describes the status of TBM design, blanket technology and materials development for ITER TBMs. The current design and R&D status of candidate TBM concepts, which include 1) a water-cooling system with a solid breeder, 2) a helium gas-cooling system with a solid breeder, 3) a lithium-lead (LiPb) breeding system, 4) a liquid lithium breeding system, and 5) a molten salt breeding system, are presented and discussed.

Tanaka, Satoru; Akiba, Masato; Enoeda, Mikio; Hasegawa, Akira; Konishi, Satoshi; Muroga, Takeo; Sagara, Akio

203

Development of low density silica aerogel as a capture medium for hyper-velocity particles  

SciTech Connect

We have developed a method of bonding silica aerogel to various substrate materials including aluminum, silicon, glass, and other aerogels, using a silicon compound. The bonds are stronger than the aerogel, they are transparent, and they have very low off-gassing. We have also improved the transparency of silica aerogels by modifying the sol-gel chemistry that results in the gel. The new aerogels have about 15% higher transmission through the visible and 85% higher transmission between 250 and 330nm wavelengths, as compared with conventional silica aerogels. The ultraviolet cut-off wavelength of the aerogel can be varied as desired with our developed method.

Hrubesh, L.W.; Poco, J.F.

1991-10-01

204

Synthesis and Use of Organic Biodegradable Aerogels as Drug Carriers.  

PubMed

Aerogels of natural polysaccharides possess both biocharacteristics of polysaccharides, such as good biological compatibility and cell or enzyme-controlled degradability, and aerogel characteristics, such as very high porosity and specific surface areas that makes them highly attractive in drug delivery. Biodegradable alginate aerogels were synthesized via a sol-gel process. In the present work two methods of ionic cross-linking were used to prepare alginate hydrogels as monoliths and spheres, which can be further easily converted to high surface area aerogels. The aerogels obtained were further used as drug carriers. We investigated the effect of process parameters, such as starting concentration and viscosity of alginate solution, on synthesis products and on model drug (nicotinic acid) release. The results indicate that by using the internal setting cross-linking method for obtaining monolithic aerogels nicotinic acid was released in a more controlled manner. The aerogels thus obtained also exhibited smaller volume shrinkage than the ones described in other publications. However, with increasing alginate concentration in both types of synthesis more compact and cross-linked aerogels were formed. PMID:21457617

Veronovski, Anja; Novak, Zoran; Knez, Zeljko

2011-03-31

205

Time Dependent Spectral Emission of Proton Bombarded Aerogels.  

National Technical Information Service (NTIS)

The University of Arizona 2 MV Van de Graaff accelerated 1 MeV protons to bombard aerogel targets. The spectroscopic emission characteristics of proton bombarded aerogels 1.68 mm - 5.50 mm thick were studied, particularly the emission as a function of bom...

E. W. Marsh

1998-01-01

206

Carbon cloth-reinforced and activated aerogel films for supercapacitors  

Microsoft Academic Search

The incorporation of carbon cloth into resorcinol formaldehyde (RF) aerogel precursors allows the manufacture of flexible, mechanically stable monolithic carbon aerogel electrodes with thicknesses in the 100 ?m range. These were used to build button cell supercapacitors (diameter: 22 mm, thickness: 6 mm) with a capacitance of about 11 F and a serial resistance of about 170 m?. These cells

C. Schmitt; H Pröbstle; J Fricke

2001-01-01

207

Organic aerogels from the polycondensation of resorcinol with formaldehyde  

Microsoft Academic Search

The polycondensation of resorcinol with formaldehyde under alkaline conditions results in the formation of surface functionalized polymer “clusters”. The covalent crosslinking of these “clusters” produces gels which are processed under supercritical conditions to obtain low density, organic aerogels ( ? 0.1 g cm-3). The aerogels are transparent, dark red in colour, and consist of interconnected colloidal-like particles with diameters of

R. W. Pekala

1989-01-01

208

Thermal Performance of a Customized Multilayer Insulation (MLI).  

National Technical Information Service (NTIS)

The thermal performance of a LH2 tank on a shroudless vehicle was investigated. The 1.52 m (60 in) tank was insulated with 2 MLI blankets consisting of 18 double aluminized Mylar radiation shields and 19 silk net spacers. The temperature of outer space wa...

K. E. Leonhard

1976-01-01

209

Thermal performance of a customized multilayer insulation (MLI)  

Microsoft Academic Search

The thermal performance of a LH2 tank on a shroudless vehicle was investigated. The 1.52 m (60 in) tank was insulated with 2 MLI blankets consisting of 18 double aluminized Mylar radiation shields and 19 silk net spacers. The temperature of outer space was simulated by using a cryoshroud which was maintained at near liquid hydrogen temperature. The heating effects

K. E. Leonhard

1976-01-01

210

Analysis of multilayer insulation between 80K and 300K  

Microsoft Academic Search

A model has been developed that can be used to determine the temperature distribution and heat transfer through a multilayer insulation (MLI) blanket. Predictions from the model were compared with a series of temperature measurements made during laboratory experiments and during a test of five superconducting magnets (dipoles) installed in a string and tested at Fermi National Accelerator Laboratory, FNAL

S. D. Augustynowicz; J. A. Demko; V. I. Datskov

1993-01-01

211

Qualification of MHD effects in dual-coolant DEMO blanket and approaches to their modelling  

Microsoft Academic Search

Design refinements of vertical insulated banana-shaped liquid metal channels are being considered as a progress of conceptual design of dual-coolant liquid metal blankets (DEMO specifications). Among them: (a) optimised channel geometry and (b) improvements on flow channel inserts.Progress of channel conceptual design is conducted in parallel with underlying physics of MHD models in diverse aspects: (1) MHD models, (2) MHD

E. Mas de les Valls; L. Batet; V. de Medina; J. Fradera; L. A. Sedano

2011-01-01

212

Fusion-Reactor Blanket-Material Safety-Compatibility Studies.  

National Technical Information Service (NTIS)

Blanket material selection for fusion reactors is strongly influenced by the desire to minimize safety and environmental concerns. Blanket material safety compatibility studies are being conducted to identify and characterize blanket-coolant-material inte...

D. W. Jeppson L. D. Muhlestein R. F. Keough S. Cohen

1982-01-01

213

75 FR 51482 - Woven Electric Blankets From China  

Federal Register 2010, 2011, 2012, 2013

...Electric Blankets From China Determination On the basis...reason of imports from China of woven electric blankets...Sunbeam Products, Inc., doing business as Jarden Consumer Solutions...electric blankets from China were being sold at...

2010-08-20

214

High resolution transmission electron microscopy of melamine-formaldehyde aerogels and silica aerogels.  

National Technical Information Service (NTIS)

The goal of the high resolution transmission electron microscopy (HRTEM) was to image the structure of two tetramethyl orthosilicate (TMOS) and two melamine-formaldehyde (MF) aerogels at the single polymer chain level(sup 1,2). With this level of structur...

G. C. Ruben

1991-01-01

215

Aerogel Keystones: Extraction Of Complete Hypervelocity Impact Events From Aerogel Collectors  

Microsoft Academic Search

In January 2006, the Stardust mission will return the first samples from a solid solar-system body since Apollo, and the first samples of contemporary interstellar dust ever collected. Although sophisticated laboratory instruments exist for the analysis of Stardust samples, techniques for the recovery of particles and particle residues from aerogel collectors remain primitive. Here we describe our recent progress in

Andrew J. Westphal; Christopher J. Snead; Anna L. Butterworth; Giles A. Graham; John P. Bradley; Saÿsa Bajt; Patrick G. Grant; Graham Bench; Sean Brennan; P Piannetta

2003-01-01

216

Aerogel keystones: Extraction of complete hypervelocity impact events from aerogel collectors  

Microsoft Academic Search

In January 2006, the Stardust mission will return the first samples from a solid solar system body beyond the Moon and the first samples of contemporary interstellar dust ever collected. Although sophisticated laboratory instruments exist for the analysis of Stardust samples, techniques for the recovery of particles and particle residues from aerogel collectors remain primitive. Here, we describe our recent

Andrew J. Westphal; Christopher Snead; Anna Butterworth; Giles A. Graham; John P. Bradley; Sasa Bajt; Patrick G. Grant; Graham Bench; Sean Brennan; Piero Pianetta

2004-01-01

217

Thermal alteration of hydrated minerals during hypervelocity capture to silica aerogel at the flyby speed of Stardust  

NASA Astrophysics Data System (ADS)

Outside the Earth's atmosphere, silica aerogel is one of the best materials to capture finegrained extraterrestrial particles in impacts at hypervelocities. Because silica aerogel is a superior insulator, captured grains are inevitably influenced by frictional heat. Therefore, we performed laboratory simulations of hypervelocity capture by using light-gas guns to impact into aerogels fine-grained powders of serpentine, cronstedtite, and Murchison CM2 meteorite. The samples were shot at >6 km s-1 similar to the flyby speed at comet P/Wild-2 in the Stardust mission. We investigated mineralogical changes of each captured particle by using synchrotron radiation X-ray diffraction (SR-XRD), transmission electron microscope (TEM), and field emission scanning electron microscope (FE-SEM). SR-XRD of each grain showed that the majority of the bulk grains keep their original mineralogy. In particular, SR-XRD and TEM investigations clearly exemplified the presence of tochilinite whose decomposition temperature is about 300 °C in the interior of the captured Murchison powder. However, TEM study of these grains also revealed that all the samples experienced melting and vesiculation on the surface. The cronstedtite and the Murchison meteorite powder show remarkable fracturing, disaggregation, melting, and vesiculation. Steep thermal gradients, about 2500 °C/?m were estimated near the surface of the grains (<2 ?m thick) by TEM observation. Our data suggests that the interior of >4 ?m across residual grains containing abundant materials that inhibit temperature rise would have not experienced >300 °C at the center.

Noguchi, Takaaki; Nakamura, Tomoki; Okudaira, Kyoko; Yano, Hajime; Sugita, Seiji; Burchell, Mark J.

2007-03-01

218

47 CFR 22.353 - Blanketing interference.  

Code of Federal Regulations, 2010 CFR

...any cases of blanketing interference in their area of responsibility...modified transmitter(s). Interference must be resolved promptly...the field strength of the electromagnetic radiation from such stations...required to resolve blanketing interference to mobile receivers or...

2010-10-01

219

47 CFR 22.353 - Blanketing interference.  

Code of Federal Regulations, 2010 CFR

...any cases of blanketing interference in their area of responsibility...modified transmitter(s). Interference must be resolved promptly...the field strength of the electromagnetic radiation from such stations...required to resolve blanketing interference to mobile receivers or...

2009-10-01

220

Thermal Performance Measurements of a 100 Percent Polyester MLI (Multilayer Insulation) System for the Superconducting Super Collider: Part 2, Laboratory Results (300K-80K).  

National Technical Information Service (NTIS)

The plastic materials used in the multilayer insulation (MLI) blankets of the superconducting magnets of the Superconducting Super Collider (SSC) are comprised entirely of polyesters. This paper reports on tests conducted in three separate experimental bl...

J. D. Gonczy W. N. Boroski R. C. Niemann

1989-01-01

221

Nano-sized Ni-doped carbon aerogel for supercapacitor.  

PubMed

Carbon aerogel was prepared by polycondensation of resorcinol with formaldehyde using sodium carbonate as a catalyst in ambient conditions. Nano-sized Ni-doped carbon aerogel was then prepared by a precipitation method in an ethanol solvent. In order to elucidate the effect of nickel content on electrochemical properties, Ni-doped carbon aerogels (21, 35, 60, and 82 wt%) were prepared and their performance for supercapacitor electrode was investigated. Electrochemical properties of Ni-doped carbon aerogel electrodes were measured by cyclic voltammetry at a scan rate of 10 mV/sec and charge/discharge test at constant current of 1 A/g in 6 M KOH electrolyte. Among the samples prepared, 35 wt% Ni-doped carbon aerogel (Ni/CA-35) showed the highest capacitance (110 F/g) and excellent charge/discharge behavior. The enhanced capacitance of Ni-doped carbon aerogel was attributed to the faradaic redox reactions of nano-sized nickel oxide. Moreover, Ni-doped carbon aerogel exhibited quite stable cyclability, indicating long-term electrochemical stability. PMID:22121750

Lee, Yoon Jae; Jung, Ji Chul; Park, Sunyoung; Seo, Jeong Gil; Baeck, Sung-Hyeon; Yoon, Jung Rag; Yi, Jongheop; Song, In Kyu

2011-07-01

222

Hypervelocity Capture of Meteoritic Particles in Nonsilica Aerogels  

SciTech Connect

The Stardust mission captured particles from the comet 81P/Wild 2 in gradient density silica aerogel and returned the collected samples to earth in 2006. The analyses of these particles have revealed several new insights into the formation of our solar system. However, since the aerogel used as the capture material was silica, the elemental analyses of the silica-rich particles were made more complicated in certain ways due to the mixing of the silicon of the particles and that of the aerogel. By using a nonsilica aerogel, future elemental analyses of silica-rich particles captured in aerogel could be made more straightforward. Resorcinol/formaldehyde (RF), alumina, and zirconia aerogels were impact tested with meteoritic fragments and the captured fragments were mapped with synchrotron-based X-ray microprobe (XRM) and the particles were analyzed with X-ray fluorescence (XRF). The resorcinol/formaldehyde aerogel proved to be the best capture material, in that it could be keystoned and XRF could be used to locate and analyze particles that were less than 10 {micro}m.

S Jones; G Flynn

2011-12-31

223

Temperature and moisture dependence of dielectric constant for silica aerogels  

SciTech Connect

The dielectric constants of silica aerogels are among the lowest measured for any solid material. The silica aerogels also exhibit low thermal expansion and are thermally stable to temperatures exceeding 500{degrees}C. However, due to the open porosity and large surface areas for aerogels, their dielectric constants are strongly affected by moisture and temperature. This paper presents data for the dielectric constants of silica aerogels as a function of moisture content at 25{degrees}C, and as a function of temperature, for temperatures in the range from 25{degrees}C to 450{degrees}C. Dielectric constant data are also given for silica aerogels that are heat treated in dry nitrogen at 500{degrees}C, then cooled to 25{degrees}C for measurements in dry air. All measurements are made on bulk aerogel spheres at 22GHz microwave frequency, using a cavity perturbation method. The results of the dependence found here for bulk materials can be inferred to apply also to thin films of silica aerogels having similar nano-structures and densities.

Hrubesh, L.H., LLNL

1997-03-01

224

Synthesis and properties of Chitosan-silica hybrid aerogels  

SciTech Connect

Chitosan, a polymer that is soluble in dilute aqueous acid, is derived from chitin, a natural polyglucosamide. Aquagels where the solid phase consists of both chitosan and silica can be easily prepared by using an acidic solution of chitosan to catalyze the hydrolysis and condensation of tetraethylorthosilicate. Gels with chitosan/TEOS mass ratios of 0.1-1.1 have been prepared by this method. Standard drying processes using CO{sub 2} give the corresponding aerogels. The amount of chitosan in the gel plays a role in the shrinkage of the aerogel during drying. Gels with the lowest chitosan/silica ratios show the most linear shrinkage, up to 24%, while those with the highest ratios show only a 7% linear shrinkage. Pyrolysis at 700 C under nitrogen produces a darkened aerogel due to the thermal decomposition of the chitosan, however, the aerogel retains its monolithic form. The pyrolyzed aerogels absorb slightly more infrared radiation in the 2-5 {micro}m region than the original aerogels. B.E.T. surface areas of these aerogels range from 470-750 m{sup 2}/g. Biocompatibility screening of this material shows a very high value for hemolysis, but a low value for cytotoxicity.

Ayers, Michael R.; Hunt, Arlon J.

2001-06-01

225

Thermal conductivity studies of a polyurea cross-linked silica aerogel-RTV 655 compound for cryogenic propellant tank applications in space  

NASA Astrophysics Data System (ADS)

Silica-based aerogel is an ideal thermal insulator with a makeup of up to 99% air associated with the highly porous nature of this material. Polyurea cross-linked silica aerogel (PCSA) has superior mechanical properties compared to the native aerogels yet retains the highly porous open pore network and functions as an ideal thermal insulator with added load-bearing capability necessary for some applications. Room temperature vulcanizing rubber-RTV 655—is a space qualified elastomeric thermal insulator and encapsulant with high radiation and temperature tolerance as well as chemical resistance. Storage and transport of cryogenic propellant liquids is an integral part of the success of future space exploratory missions and is an area under constant development. Limitations and shortcomings of current cryogenic tank materials and insulation techniques such as non-uniform insulation layers, self-pressurization, weight and durability issues of the materials used, has motivated the quest for alternative materials. Both RTV 655 and PCSA are promising space qualified materials with unique and tunable microscopic and macroscopic properties making them attractive candidates for this study. In this work, the effect of PCSA geometry and volume concentration on the thermal behavior of RTV 655—PCSA compound material has been investigated at room temperature and at a cryogenic temperature. Macroscopic and microscopic PCSA material was encapsulated at increasing concentrations in an RTV 655 elastomeric matrix. The effect of pulverization on the nanopores of PCSA as a method for creating large quantities of homogeneous PCSA microparticles has also been investigated and is reported. The PCSA volume concentrations ranged between 22% and 75% for both geometries. Thermal conductivity measurements were performed based on the steady state transient plane source method.

Sabri, F.; Marchetta, J.; Smith, K. M.

2013-10-01

226

Superhydrophobic silica aerogels based on methyltrimethoxysilane precursor  

Microsoft Academic Search

The experimental results on the synthesis and physicochemical properties of superhydrophobic silica aerogels, with the highest ever obtained contact angle (?173°), using methyltrimethoxysilane (MTMS) precursor, methanol (MeOH) solvent and ammonium hydroxide (NH4OH) catalyst, are reported. The molar ratios of NH4OH\\/MTMS (N), H2O\\/MTMS (H) and MeOH\\/MTMS (M) were varied from 4.25×10?2 to 3.5×10?1, 2 to 10 and 1.75 to 17, respectively.

A. Venkateswara Rao; Manish M. Kulkarni; D. P. Amalnerkar; Tanay Seth

2003-01-01

227

Production and Rare Earth Doping of Aerogels  

NASA Astrophysics Data System (ADS)

We present recent studies into several methods for making Aerogels. We used both critical point drying methods and chemical dehydroxylation to achieve low density glasses. We used an SEM to characterize the increased pore sizes in these glass materials. In addition, we will present preliminary results of our efforts to add rare earth ions to the glass structure. We are attempting to add the rare earth ions to the glass while avoiding the clustering problems normally encountered in the sol-gel synthesis technique.

Montejo, Genderzon; Sanchez, Freddy; Wenzlau, Dylan; Hoffman, Kurt

2010-10-01

228

Blanket materials for DT fusion reactors  

SciTech Connect

This paper presents an overview of the critical materials issues that must be considered in the development of a tritium breeding blanket for a tokamak fusion reactor that operates on the D-T-Li fuel cycle. The primary requirements of the blanket system are identified and the important criteria that must be considered in the development of blanket technology are summarized. The candidate materials are listed for the different blanket components, e.g., breeder, coolant, structure and neutron multiplier. Three blanket concepts that appear to offer the most potential are: (1) liquid-metal breeder/coolant, (2) liquid-metal breeder/separate coolant, and (3) solid breeder/separate coolant. The major uncertainties associated with each of the design concepts are discussed and the key materials R and D requirements for each concept are identified.

Smith, D.L.

1981-01-01

229

Lithium titanate aerogel for advanced lithium-ion batteries.  

PubMed

This work details the synthesis and characterization of a novel lithium titanate aerogel as an anode material for lithium ion batteries. Excessive loss of lithium during supercritical drying can be overcome by increasing the lithium precursor concentration during synthesis. Chronopotentiometry shows the aerogel to have a capacity about 80 % of theoretical at a symmetric C/3 rate, which is comparable to a commercial product. Cyclic voltammetry reveals a batt-cap behavior for the high-surface area aerogel, implying the potential for improved rate capability if electrical conductivity can be maintained. PMID:22496498

Maloney, Ryan P; Kim, Hyun Joong; Sakamoto, Jeffrey S

2012-04-19

230

Aerogels for microelectronic applications: Fast, inexpensive, and light as air  

SciTech Connect

Silica aerogel consists of bonded silicon and oxygen joined into log strands, which are randomly linked together with pockets of air between them. Discovered in the 1930s, the material was thought to have little use outside of theoretical science. However, with the advent of greatly improved processing techniques, such as those developed at Lawrence Livermore National Laboratory, aerogels are on the verge of commercialization. This document describes the need for aerogels in the high-speed microelectronics industry, and state of the art processing techniques. Collaboration is welcomed in the endeavor.

Contolini, R.J.; Hrubesh, L.W.; Bernhardt, A.F.

1993-03-25

231

Venting through multiple-layer insulation on Space Station Freedom. II - Ascent rate pressure chamber testing  

NASA Astrophysics Data System (ADS)

A test was conducted to determine the venting characteristics of the multiple-layer insulation (MLI) to be installed on the Space Station Freedom (SSF). A full MLI blanket with inter-blanket joints was installed onto a model of a section of the SSF pressure wall, support structure, and debris shield. Data were taken from this test and were used to predict the venting of the actual Space Station pressure-wall/MLI/debris-shield assemply during launch and possible re-entry. It was found that the pressure differences across the debris shields and MLI blankets were well within the specified limits in all cases.

Sharp, Jeffrey B.; Buitekant, Alan; Fay, John F.; Holladay, Jon B.

1993-01-01

232

ADVANCED HIGH PERFORMANCE SOLID WALL BLANKET CONCEPTS  

SciTech Connect

OAK A271 ADVANCED HIGH PERFORMANCE SOLID WALL BLANKET CONCEPTS. First wall and blanket (FW/blanket) design is a crucial element in the performance and acceptance of a fusion power plant. High temperature structural and breeding materials are needed for high thermal performance. A suitable combination of structural design with the selected materials is necessary for D-T fuel sufficiency. Whenever possible, low afterheat, low chemical reactivity and low activation materials are desired to achieve passive safety and minimize the amount of high-level waste. Of course the selected fusion FW/blanket design will have to match the operational scenarios of high performance plasma. The key characteristics of eight advanced high performance FW/blanket concepts are presented in this paper. Design configurations, performance characteristics, unique advantages and issues are summarized. All reviewed designs can satisfy most of the necessary design goals. For further development, in concert with the advancement in plasma control and scrape off layer physics, additional emphasis will be needed in the areas of first wall coating material selection, design of plasma stabilization coils, consideration of reactor startup and transient events. To validate the projected performance of the advanced FW/blanket concepts the critical element is the need for 14 MeV neutron irradiation facilities for the generation of necessary engineering design data and the prediction of FW/blanket components lifetime and availability.

WONG, CPC; MALANG, S; NISHIO, S; RAFFRAY, R; SAGARA, S

2002-04-01

233

Low dielectric polyimide aerogels as substrates for lightweight patch antennas.  

PubMed

The dielectric properties and loss tangents of low-density polyimide aerogels have been characterized at various frequencies. Relative dielectric constants as low as 1.16 were measured for polyimide aerogels made from 2,2'-dimethylbenzidine (DMBZ) and biphenyl 3,3',4,4'-tetracarbozylic dianhydride (BPDA) cross-linked with 1,3,5-triaminophenoxybenzene (TAB). This formulation was used as the substrate to fabricate and test prototype microstrip patch antennas and benchmark against state of practice commercial antenna substrates. The polyimide aerogel antennas exhibited broader bandwidth, higher gain, and lower mass than the antennas made using commercial substrates. These are very encouraging results, which support the potential advantages of the polyimide aerogel-based antennas for aerospace applications. PMID:23134844

Meador, Mary Ann B; Wright, Sarah; Sandberg, Anna; Nguyen, Baochau N; Van Keuls, Frederick W; Mueller, Carl H; Rodríguez-Solís, Rafael; Miranda, Félix A

2012-11-07

234

Partially hydrolized alkoxysilanes as precursors for silica aerogels  

SciTech Connect

The classical sol-gel process for synthesizing SiO/sub 2/ aerogels involves the hydrolysiscondensation of tetraethyoxysilane (TEOS) andor teramethyoxysilane (TMOS) to produce a gel which can then be supercritically extracted to a low density, highly porous aerogel glass. Controlled hydrolysis of TEOS and TMOS leads to partially hydrolyzed compounds that can be subsequently water processed to form silica aerogels in the density range from .020 to .500 gcc. The partially hydrolyzed compounds are stable when sealed from moist air and can be stored for future use. We discuss the controlled conditions used to obtain these compounds and present data that characterize their structure. We detail the procedures for preparing the wide range of aerogel densities. We also report on their use as an adhesive. 4 refs., 5 figs.

Tillotson, T.M.; Hrubesh, L.W.; Thomas, I.M.

1988-03-31

235

Texture of chromia aerogels and structure of their nanocrystals  

Microsoft Academic Search

Mesoporous chromia aerogels with a surface area of 484-735 m2g-1 a pore volume of 0.4- 0.9 cm3 g-1 and a pore diameter of 3-9 nm were prepared by urea-assisted homogeneous precipitation from an aqueous Cr(NC3)3 solution, followed by continuous supercritical CO2 extraction. The aerogels were characterized by means of N2-adsorption isotherms, AA, HR- TEM, FTIR, thermoanalytical methods TPD, TPO, DSC

M. Abecassis-Wolfovich; H. Rotter; M. V. Landau; E. Korin; A. I. Erenburg; D. Mogilyansky; E. Garshtein

2003-01-01

236

Low density TEOS based silica aerogels using methanol solvent  

Microsoft Academic Search

Highly transparent monolithic silica aerogels based on the TEOS precursor were prepared by the two-step (acid-base) sol–gel\\u000a process. The hydrolysis and condensation reactions of tetraethoxysilane (TEOS) proceeded in methanol solvent with oxalic acid\\u000a and NH4OH as the catalysts, respectively. The wet gels were supercritically dried using methanol. The aerogels were characterized\\u000a by transmission electron microscopy (TEM) and measurements of optical

Sharad D. Bhagat; Hiroshi Hirashima; A. Venkateswara Rao

2007-01-01

237

AEM and HREM evaluation of carbon nanostructures in silica aerogels  

SciTech Connect

Nanostructured carbon has been deposited in silica aerogels by chemical vapor infiltration using acetylene or ferrocene at moderate temperatures. Using analytical electron microscopy and high-resolution electron microscopy, we have observed various carbon rings and nanotubes in the silica aerogel-based carbon composite. Both X-ray microanalysis and nano-probe diffraction techniques have been used to confirm the presence of those carbon nanostructures. Morphologies and structural properties of the carbon nanotubes and rings have also been examined in detail.

Song, X.Y.; Cao, W.; Hunt, A.J.

1994-04-01

238

Modeling of thermal conduction in granular silica aerogels  

Microsoft Academic Search

Monolithic silica aerogels of large sizes are difficult to synthesize and manipulate. Granular form is the easiest way of\\u000a conditioning them. One of the most promising applications is probably thermal superinsulation applied to the building sector.\\u000a To understand and quantify thermal conduction in granular silica aerogels, numerical simulations are necessary. Our method\\u000a is based on two steps: determining properties of

S. Spagnol; B. Lartigue; A. Trombe; V. Gibiat

2008-01-01

239

Impact Features and Projectile Residues in Aerogel Exposed on Mir  

Microsoft Academic Search

Approximately 0.63 m2 of SiO2-based aerogel (0.02 g cm?3) was exposed for 18 months on the Mir Station to capture hypervelocity particles from both man-made and natural sources. Optical inspection revealed two major classes of hypervelocity impact features in the aerogel: (1) long, carrot-shaped tracks, well known from laboratory impact experiments, that exhibit a depth- (t) to-diameter (D) relationship of

F. Hörz; M. E. Zolensky; R. P. Bernhard; T. H. See; J. L. Warren

2000-01-01

240

Titanium-doped silica aerogels for lightweighted optics  

NASA Astrophysics Data System (ADS)

A process is presented for fabricating titanium doped silica aerogels. Aerogels were produced by the hydrolysis of TEOS and titanium isopropoxide in ethanol and then supercritically dried in a nitrogen overpressure. A detailed study of gelling and annealing was performed to minimize shrinkage and produce dried gels with densities less than 10% of ordinary glass. Lightweighted structures with densities between 0.16 g/cm3 and 0.06 g/cm3 were produced.

Pazol, Brian G.; Defranzo, Anthony C.

1993-12-01

241

Fabrication of mesoporous titania aerogel film via supercritical drying  

Microsoft Academic Search

Using a supercritical drying method, fluorine-doped tin oxide (FTO) glass was coated with a mesoporous titania aerogel film\\u000a prepared from titania sols with viscosity between 10 and 60 cP that had been spin coated, immersed in IPA solution, and aged\\u000a at least 3 weeks. Mesoporous titania aerogel film has an anatase structure, and an average porosity of 76%. It is hydrophilic,\\u000a and

Won Ju Sung; Sang-Hoon Hyun; Dong-Hyun Kim; Doo-Soo Kim; Jungho Ryu

2009-01-01

242

Integration of carbon aerogels in PEM fuel cells  

Microsoft Academic Search

We prepared resorcinol–formaldehyde (RF) aerogel films with a high molar ratio of resorcinol\\/catalyst (R\\/C) of about 1500 and a low mass ratio of 30%. At the onset of the gelation process, organic fibers or carbon fiber fleece were added to the sol in order to increase the mechanical stability. Upon pyrolysis the RF-aerogel as well as the organic fibers were

M. Glora; M Wiener; R Petri?evi?; H Pröbstle; J Fricke

2001-01-01

243

A silica aerogel counter for large-acceptance hadron detection  

Microsoft Academic Search

In order to study the feasibility of large scale multicell counters, two prototypes with respective detection area 80*40 cm\\/sup 2\\/ and 65*31 cm\\/sup 2\\/ were constructed. The Cerenkov light produced in silica aerogel of refractive index n=1.03 and diffused in a well optimized box was detected with five quantacon photomultipliers. Results of beam tests concerning the aerogel thickness, the diffusing

C. Arnault; P. Heusse; P. Barberis; U. Dosselli; W. Buckhardt; F. Montanet; G. Bassompierre; G. Coignet; M. Schneegans

1980-01-01

244

APT target-blanket fabrication development  

SciTech Connect

Concepts for producing tritium in an accelerator were translated into hardware for engineering studies of tritium generation, heat transfer, and effects of proton-neutron flux on materials. Small-scale target- blanket assemblies were fabricated and material samples prepared for these performance tests. Blanket assemblies utilize composite aluminum-lead modules, the two primary materials of the blanket. Several approaches are being investigated to produce large-scale assemblies, developing fabrication and assembly methods for their commercial manufacture. Small-scale target-blanket assemblies, designed and fabricated at the Savannah River Site, were place in Los Alamos Neutron Science Center (LANSCE) for irradiation. They were subjected to neutron flux for nine months during 1996-97. Coincident with this test was the development of production methods for large- scale modules. Increasing module size presented challenges that required new methods to be developed for fabrication and assembly. After development, these methods were demonstrated by fabricating and assembling two production-scale modules.

Fisher, D.L.

1997-06-13

245

Structural Materials for Fusion Reactor Blanket Systems.  

National Technical Information Service (NTIS)

Consideration of the required functions of the blanket and the general chemical, mechanical, and physical properties of candidate tritium breeding materials, coolants, structural materials, etc., leads to acceptable or compatible combinations of materials...

E. E. Bloom D. L. Smith

1984-01-01

246

BWTR (Boiling Water Tokamak Reactor) Blanket Study.  

National Technical Information Service (NTIS)

The NUWMAK design is a second generation reactor design study. It utilizes the experiences we obtained from UWMAK series designs, combined with recent development in plasma physics and aimed toward a more optimized reactor design. The blanket for NUWMAK i...

D. K. Sze C. W. Maynard I. N. Sviatoslavsky E. T. Cheng C. C. Wang

1978-01-01

247

Improved Acoustic Blanket Developed and Tested.  

National Technical Information Service (NTIS)

Acoustic blankets are used in the payload fairing of expendable launch vehicles to reduce the fairing's interior acoustics and the subsequent vibration response of the spacecraft. The Cassini spacecraft, to be launched on a Titan IV in October 1997, requi...

1996-01-01

248

Recyclable Solid Blanket for a Fusion Reactor  

NASA Astrophysics Data System (ADS)

Neutron damage and tritium inventory will limit the lifetime of inner wall components of a fusion reactor, leading to increased operation cost and possibly making it economically unattractive. Thick liquid walls may be a solution to this; however, at present the feasibility of forming and maintaining thick liquid walls remains to be demonstrated for a tokamak configuration. Here it is proposed to construct inner wall components of a reactor using a meltable material. During the normal operation the blanket is maintained in the solid state. After some period of operation, when a critical level of neutron damage and tritium inventory in the blanket is accumulated, the structure is melted and drained out of the reactor chamber. After that, by bringing in fresh liquid blanket material and freezing it to the solid state on the walls, the blanket is rebuilt. Thus the blanket is periodically replaced without opening up the reactor chamber, relatively easily compared to a solid blanket. Preliminary calculations demonstrate that such system can satisfy the basic requirements of thermal transport and tritium breeding in a reactor.

Umansky, M. V.

2009-11-01

249

Tritium control in helium-cooled blankets  

NASA Astrophysics Data System (ADS)

As a part of the Blanket Comparison and Selection study (BCSS), GA Technologies as responsible for the design of helium-cooled, solid- and liquid-metal breeder blankets. Conceptual blanket designs are developed, including the consideration of the generation, transport, and extraction of tritium. Evaluations are made of the inventory and leakage of tritium for helium-cooled Li2O and LiAlO2 and liquid lithium breeder blankets for tokamak and tandem mirror reactors. To facilitate the evaluation, a solid breeder tritium code TRIT4 is developed. The results from this study indicate that tritium inventories and leakages are acceptable for the proposed helium-cooled blankets. An assumption made in the tritium leakage calculations is that tritium is released to the helium purge and coolant streams as T2 and remains in that form. If oxidation to T2O is possible, significant reduction in the tritium leakage will be possible. It is concluded that more experimental data on breeder material properties and tritium permeation behavior are needed. However, an adequate number of techniques is available to control the breeder tritium inventory and leakage to an acceptable level in helium-cooled solid- and lithium-breeder blankets.

Wong, C. P. C.; Maya, I.; Kessel, C.; Roelant, D.; Schultz, K. R.

1985-06-01

250

Effective optical constants {ital n} and κ and extinction coefficient of silica aerogel  

Microsoft Academic Search

In this work the normal reflectance, {ital R}, at a planar silica aerogel interface and the normal transmittance, {ital T}, of a silica aerogel slab were measured using a Fourier Transform Infrared Spectrometer. Two procedures were used to obtain the effective optical constants, i.e., the refractive index {ital n} and the absorption index κ, of silica aerogel. One procedure determined

J. S. Zeng; R. Greif; P. Stevens; M. Ayers; A. Hunt

1996-01-01

251

Theoretical modeling of carbon content to minimize heat transfer in silica aerogel  

Microsoft Academic Search

Silica aerogel has a small absorption coefficient over the range 3–8 ?m where significant thermal energy is transferred by radiation. Adding carbon to silica aerogel reduces thermal radiation but increases solid conduction. Whether the total energy transfer increases or decreases depends on the carbon content. This paper presents a theoretical method for determining the optimal carbon-loading level in silica aerogel

S. Q. Zeng; A. Hunt; R. Greif

1995-01-01

252

Synthesis and magnetic properties of iron oxide–silica aerogel nanocomposites  

Microsoft Academic Search

Iron oxide–silica nanocomposite aerogels were produced by sol–gel procedure followed by the hypercritical evaporation of the solvent. Aerogels hosting maghemite were synthesized from the precursors TEOS and TMOS. Mean oxide particle size seems to be strongly influenced by the solvent. The magnetic properties of the iron oxide particles hosted in silica aerogeles pores were studied by means of magnetometry and

M. B. Fernández van Raap; F. H. Sanchez; A. G. Leyva; M. L. Japas; E. Cabanillas; H. Troiani

2007-01-01

253

Deposition of ruthenium nanoparticles on carbon aerogels for high energy density supercapacitor electrodes  

Microsoft Academic Search

The preparation and characterization of high surface area ruthenium\\/carbon aerogel composite electrodes for use in electrochemical capacitors is reported. These new materials have been prepared by the chemical vapor impregnation of ruthenium into carbon aerogels to produce a uniform distribution of adherent â20 â« nanoparticles on the aerogel surface. The electrochemically oxidized ruthenium particles contribute a pseudocapacitance to the electrode

J. M. Miller; B. Dunn; T. D. Tran; R. W. Pekala

1997-01-01

254

Comparison of lithium and the eutectic lead lithium alloy, two candidate liquid metal breeder materials for self-cooled blankets  

SciTech Connect

Liquid metals are attractive candidates for both near-term and long-term fusion applications. The subjects of this comparison are the differences between the two candidate liquid metal breeder materials Li and LiPb for use in breeding blankets in the areas of neutronics, magnetohydrodynamics, tritium control, compatibility with structural materials, heat extraction system, safety, and required R&D program. Both candidates appear to be promising for use in self-cooled breeding blankets which have inherent simplicity with the liquid metal serving as both breeders and coolant. The remaining feasibility question for both breeder materials is the electrical insulation between liquid metal and duct walls. Different ceramic coatings are required for the two breeders, and their crucial issues, namely self-healing of insulator cracks and radiation induced electrical degradation are not yet demonstrated. Each liquid metal breeder has advantages and concerns associated with it, and further development is needed to resolve these concerns.

Malang, S. [Kernforschungszentrum Karlsruhe GmbH (Germany); Mattas, R. [Argonne National Lab., IL (United States)

1994-06-01

255

Current Trends of Blanket Research and Deveopment in Japan 3.Blanket Designs in Fusion Power Reactors  

NASA Astrophysics Data System (ADS)

The main functions of the blanket in fusion power reactors are basically independent of the type of magnetic fusion reactor (tokamak, helical, etc.) and inertia fusion. However, from technical point of view, many candidate designs of blanket have been proposed depending on the particular reactor concepts. Their main features are characterized for the recent typical designs, and key issues are defined.

Sagara, Akio; Enoeda, Mikio; Nishio, Satoshi; Kozaki, Yasuji

256

Summary report for ITER task - T68: MHD facility preparation for Li/V blanket option  

SciTech Connect

A key feasibility issue for the ITER Vanadium/Lithium breeding blanket is the question of insulator coatings. Design calculations show that an electrically insulating layer is necessary to maintain an acceptably low MHD pressure drop. To enable experimental investigations of the MHD performance of candidate insulator materials and the technology for putting them in place, the room-temperature ALEX (Argonne`s Liquid Metal EXperiment) NaK facility was upgraded to a 300{degrees}C lithium system. The objective of this upgrade was to modify the existing facility to the minimum extent necessary, consistent with providing a safe, flexible, and easy to operate MHD test facility which uses lithium at ITER-relevant temperatures, Hartmann numbers, and interaction parameters. The facility was designed to produce MHD pressure drop data, test section voltage distributions, and heat transfer data for mid-scale test sections and blanket mockups. The system design description for this lithium upgrade of the ALEX facility is given in this document.

Reed, C.B.; Haglund, R.C.; Miller, M.E. [and others

1995-08-01

257

Development of low density silica aerogel as a capture medium for hyper-velocity particles. Summary report for FY 1991  

SciTech Connect

We have developed a method of bonding silica aerogel to various substrate materials including aluminum, silicon, glass, and other aerogels, using a silicon compound. The bonds are stronger than the aerogel, they are transparent, and they have very low off-gassing. We have also improved the transparency of silica aerogels by modifying the sol-gel chemistry that results in the gel. The new aerogels have about 15% higher transmission through the visible and 85% higher transmission between 250 and 330nm wavelengths, as compared with conventional silica aerogels. The ultraviolet cut-off wavelength of the aerogel can be varied as desired with our developed method.

Hrubesh, L.W.; Poco, J.F.

1991-10-01

258

Insulation resistance of mineral-insulated cables  

NASA Astrophysics Data System (ADS)

The insulation characteristics of Al203, and Mg0 insulated cables are summarized. The insulation resistance of Mg0 insulated cables normally attains 5000 ohms/m at 1000 C, although values of up to 5000 ohms at 1000 C can be realised. The insulation resistance increases by a power of 10 per 100 K fall in temperature. The insulation resistance of Al203 insulated cables in the temperature range from 600 to 1000 C is 10 billion to 100 billion ohms/m. The addition of BN increases insulation resistance over small boundaries, but results vary widely between cables. The insulation resistance of cables whose insulating material is filled with argon, helium or nitrogen at 25 bar is improved by half a power of 10 at 1000 C.

Gerlach, O.

1982-01-01

259

Deposition of ruthenium nanoparticles on carbon aerogels for high energy density supercapacitor electrodes  

SciTech Connect

The preparation and characterization of high surface area ruthenium/carbon aerogel composite electrodes for use in electrochemical capacitors is reported. These new materials have been prepared by the chemical vapor impregnation of ruthenium into carbon aerogels to produce a uniform distribution of adherent {approx}20 {angstrom} nanoparticles on the aerogel surface. The electrochemically oxidized ruthenium particles contribute a pseudocapacitance to the electrode and dramatically improve the energy storage characteristics of the aerogel. These composites have demonstrated specific capacitances in excess of 200 F/g, in comparison to 95 F/g for the untreated aerogel.

Miller, J.M.; Dunn, B. [Univ. of California, Los Angeles, CA (United States). Dept. of Materials Science and Engineering; Tran, T.D.; Pekala, R.W. [Lawrence Livermore National Labs., CA (United States). Chemical Sciences Div.

1997-12-01

260

Multilayer insulation (MLI) in the Superconducting Super Collider: A practical engineering approach to physical parameters governing MLI thermal performance  

SciTech Connect

Multilayer insulation (MLI) is employed in cryogenic devices to control the heat load of those devices. The physics defining the thermal performance of an MLI system is extremely complex due to the thermal dynamics of numerous interdependent parameters which in themselves contribute differently depending on whether boundary conditions are transient or steady-state. The Multilayer Insulation system for the Superconducting Super Collider (SSC) consists of full cryostat length assemblies of aluminized polyester film, fabricated in the form of blankets, and installed as blankets to the 4.5K cold mass, and the 20K and 80K thermal radiation shields. Approximately 40,000 blankets will be required in the 10,000 cryogenic devices comprising the SSC accelerator. Each blanket will be nearly 56 feet long by 6 feet wide and will consist of as many as 32 reflective and 31 spacer layers of material. Discussed are MLI material choices, and the physical parameters which contribute to the operational performance of MLI systems. Disclosed is a method for fabricating MLI blankets by employing a large diameter winding mandrel having a circumference sufficient for the required blanket length. The blanket fabrication method assures consistency in mass produced MLI blankets by providing positive control of the dimensional parameters which contribute to the MLI blanket thermal performance. The fabrication method can be used to mass produce prefabricated MLI blankets that by virtue of the product have inherent features of dimensional stability, three-dimensional uniformity, controlled layer density, layer-to-layer registration, interlayer cleanliness, and interlayer material to accommodate thermal contraction differences. 9 refs., 4 figs., 2 tabs.

Gonczy, J.D.; Boroski, W.N.; Niemann, R.C.

1989-03-01

261

Conversion of a room temperature NaK loop to a high temperature MHD facility for Li/V blanket testing  

SciTech Connect

The Vanadium/Lithium system has been the recent focus of ANL`s Blanket Technology Program, and for the last several years, ANL`s Liquid Metal Blanket activities have been carried out in direct support of the ITER (International Thermonuclear Experimental Reactor) breeding blanket task area. A key feasibility issue for the ITER Vanadium/Lithium breeding blanket is the development of insulator coatings. Design calculations, Hua and Gohar, show that an electrically insulating layer is necessary to maintain an acceptably low magnetohydrodynamic (MHD) pressure drop in the current ITER design. Consequently, the decision was made to convert Argonne`s Liquid Metal EXperiment (ALEX) from a 200{degree}C NaK facility to a 350{degree}C lithium facility. The upgraded facility was designed to produce MHD pressure drop data, test section voltage distributions, and heat transfer data for mid-scale test sections and blanket mockups at Hartmann numbers (M) and interaction parameters (N) in the range of 10{sup 3} to 10{sup 5} in lithium at 350{degree}C. Following completion of the upgrade work, a short performance test was conducted, followed by two longer, multiple-hour, MHD tests, all at 230{degree}C. The modified ALEX facility performed up to expectations in the testing. MHD pressure drop and test section voltage distributions were collected at Hartmann numbers of 1000. 4 refs., 2 figs.

Reed, C.B.; Haglund, R.C.; Miller, M.E.; Nasiatka, J.R. [Argonne National Lab., IL (United States); Kirillov, I.R.; Ogorodnikov, A.P.; Preslitski, G.V.; Goloubovitch, G.P. [D.V. Efremov Scientific Research Inst. of Electrophysical Apparatus, St. Petersburg (Russian Federation); Xu, Z.Y.

1996-12-31

262

Some comments on superfluid 3He placed in globally deformed aerogel  

NASA Astrophysics Data System (ADS)

New experimental results focused on the behavior of the superfluid A-like phase placed in globally deformed aerogel environment are considered. We compare experimental data collected by using optically attested axially stretched silica aerogel, on the one hand, and "nematically ordered" aerogel consisting of nearly parallel Al2O3 · H2O polymer strands, on the other. In the case of axially stretched silica aerogel the point of view was adopted according to which the orbital anisotropy axis l? is long-ranged. The experiments were carried out by pulsed NMR techniques in keeping the direction of an externally applied magnetic field normal to aerogel stretching axis. We have generalized the dipole-locked configuration for arbitrary angle of inclination of the magnetic field with respect to aerogel stretching axis. The experimental data collected in using "nematically ordered" aerogel cannot be reconciled with above-mentioned results.

Baramidze, G. A.; Kharadze, G. A.

2013-08-01

263

The requirements for processing tritium recovered from liquid lithium blankets: The blanket interface  

SciTech Connect

We have initiated a study to define a blanket processing mockup for Tritium Systems Test Assembly. Initial evaluation of the requirements of the blanket processing system have been started. The first step of the work is to define the condition of the gaseous tritium stream from the blanket tritium recovery system. This report summarizes this part of the work for one particular blanket concept, i.e., a self-cooled lithium blanket. The total gas throughput, the hydrogen to tritium ratio, the corrosive chemicals, and the radionuclides are defined. The key discoveries are: the throughput of the blanket gas stream (including the helium carrier gas) is about two orders of magnitude higher than the plasma exhaust stream;the protium to tritium ratio is about 1, the deuterium to tritium ratio is about 0.003;the corrosion chemicals are dominated by halides;the radionuclides are dominated by C-14, P-32, and S-35;their is high level of nitrogen contamination in the blanket stream. 77 refs., 6 figs., 13 tabs.

Clemmer, R.G.; Finn, P.A.; Greenwood, L.R.; Grimm, T.L.; Sze, D.K.; Bartlit, J.R.; Anderson, J.L.; Yoshida, H.; Naruse

1988-03-01

264

Superfluid transition to ABM state of 3He in aerogel  

NASA Astrophysics Data System (ADS)

Stability of the ABM pairing state in aerogel is studied in order to identify the equal-spin pairing (ESP) state of superfluid 3He there close to the transition temperature Tc(P). It is shown by examining Tc(P) beyond the mean-field approximation that the quenched disorder makes the normal to ABM transition point higher compared with that of the normal to BW transition over a wider pressure range than in the bulk case. If the ESP state in 3He in aerogel is the ABM state, the present result naturally explains why the ESP state in aerogel at least upon cooling is realized even at lower pressures than the so-called PCP in the bulk case.

Aoyama, Kazushi; Ikeda, Ryusuke

2005-08-01

265

Thermally distinct ejecta blankets from Martian craters  

NASA Astrophysics Data System (ADS)

A study of Martian ejecta blankets is carried out using the high-resolution thermal IR/visible data from the Termoskan instrument aboard Phobos '88 mission. It is found that approximately 100 craters within the Termoskan data have an ejecta blanket distinct in the thermal infrared (EDITH). These features are examined by (1) a systematic examination of all Termoskan data using high-resolution image processing; (2) a study of the systematics of the data by compiling and analyzing a data base consisting of geographic, geologic, and mormphologic parameters for a significant fraction of the EDITH and nearby non-EDITH; and (3) qualitative and quantitative analyses of localized regions of interest. It is noted that thermally distinct ejecta blankets are excellent locations for future landers and remote sensing because of relatively dust-free surface exposures of material excavated from depth.

Betts, B. H.; Murray, B. C.

1993-06-01

266

First Wall, Blanket, Shield Engineering Technology Program  

SciTech Connect

The First Wall/Blanket/Shield Engineering Technology Program sponsored by the Office of Fusion Energy of DOE has the overall objective of providing engineering data that will define performance parameters for nuclear systems in advanced fusion reactors. The program comprises testing and the development of computational tools in four areas: (1) thermomechanical and thermal-hydraulic performance of first-wall component facsimiles with emphasis on surface heat loads; (2) thermomechanical and thermal-hydraulic performance of blanket and shield component facsimiles with emphasis on bulk heating; (3) electromagnetic effects in first wall, blanket, and shield component facsimiles with emphasis on transient field penetration and eddy-current effects; (4) assembly, maintenance and repair with emphasis on remote-handling techniques. This paper will focus on elements 2 and 4 above and, in keeping with the conference participation from both fusion and fission programs, will emphasize potential interfaces between fusion technology and experience in the fission industry.

Nygren, R.E.

1982-01-01

267

Synthesis of Highly Crystalline sp(2)-Bonded Boron Nitride Aerogels.  

PubMed

sp(2)-Bonded boron nitride aerogels are synthesized from graphene aerogels via carbothermal reduction of boron oxide and simultaneous nitridation. The color and chemical composition of the original gel change dramatically, while structural features down to the nanometer scale are maintained, suggesting a direct conversion of the carbon lattice to boron nitride. Scanning and transmission electron microscopies reveal a foliated architecture of wrinkled sheets, a unique morphology among low-density, porous BN materials. The converted gels display a high degree of chemical purity (>95%) and crystalline order and exhibit unique cross-linking structures. PMID:24011289

Rousseas, Michael; Goldstein, Anna P; Mickelson, William; Worsley, Marcus A; Woo, Leta; Zettl, Alex

2013-09-12

268

Fabrication of gradient density SiO 2 aerogel  

Microsoft Academic Search

With tetraethoxysilane as the organic precursor, gradient density aerogels were fabricated by three different methods: layer-by-layer\\u000a gelation, sol-co-gelation and continuous formation technics. Through layer-by-layer method, a 5-layer graded density silica\\u000a aerogel whose density ranges from 50 to 200 mg\\/cm3 was obtained, but it existed a dense skin between adjacent layers which could result in density mutation in the interface.\\u000a In order

Jia-Yin GuiBin; Bin Zhou; Yan-Hong Zhong; Ai Du; Jun Shen

2011-01-01

269

A Silica Aerogel Counter for Large-Acceptance Hadron Detection  

NASA Astrophysics Data System (ADS)

In order to study the feasibility of large scale multicell counters, two prototypes with respective detection area 80 × 40 cm2 and 65 × 31 cm2 were constructed. The Cerenkov light produced in silica aerogel of refractive index n = 1.03 and diffused in a well optimized box was detected with five quantacon photomultipliers. Results of beam tests concerning the aerogel thickness, the diffusing material and box shape, the influence of the incident particle position and the momentum threshold curves for ?, K and p are presented. The final design of a multicell detection system is given.

Arnault, C.; Barberis, P. L.; Bassompierre, G.; Burkhardt, W.; Coignet, G.; Dosselli, U.; Heusse, P.; Montanet, F.; Schneegans, M.

1981-04-01

270

Study of lithium diffusion through vanadium pentoxide aerogel  

NASA Astrophysics Data System (ADS)

Good electrode materials play an important part in rechargeable Li batteries. In this paper, safe and inexpensive vanadium pentoxide (V2O5) aerogel materials were used as cathode materials. We discussed preparation of the films and lithium ion diffusion at the interface between the cathode and electrolyte by potential-step current transient technique and digital simulations. The results showed that diffusion coefficient (DLi) of the V2O5 aerogel film was 9.18×10-14cm2/s and exchange current was 12.5×10-6A at potential step 3.6~3.5VLi/Li+.

Wang, Airong; Wu, Guangming; Yang, Hui-yu; Zhang, Ming-xia; Fang, Xingmei; Yang, Xiao-yun; Zhou, Bin; Shen, Jun

2008-03-01

271

Natural circulation in fusion reactor blankets  

NASA Astrophysics Data System (ADS)

The relative importance of natural circulation and heat conduction as heat transfer mechanisms in lithium, sodium and flibe is investigated for a range of magnetic field strengths of interest in fusion reactor blankets. The calculations are based on an order-of-magnitude simplification of the fluid equations, and a modified version of the fission reactor thermal-hydraulic code THERMIT. The results show that conduction is dominant for lithium (and sodium) for typical magnetic field strengths, but that natural circulation is most important in flibe. In fact, preliminary calculations suggest the possibility of a simple flibe blanket module with cooling only along the module boundaries.

Gierszewski, P. J.; Mikic, B.; Todreas, N. E.

1980-07-01

272

Review of advances in development of vanadium alloys and MHD insulator coatings  

Microsoft Academic Search

Recent progress in the development of low activation vanadium alloys and MHD insulator coatings for a Li-self cooled blanket is reviewed. Research progress in vanadium alloys is highlighted by technology for fabricating creep tubes, comparison of thermal creep in vacuum and Li, understanding impurity transfer between vanadium alloys and Li and its impact on mechanical properties, behavior of hydrogen and

Takeo Muroga; J. M. Chen; V. M. Chernov; K. Fukumoto; David T Hoelzer; Richard Kurtz; T. Nagasaka; Bruce A Pint; M. Satou; Akihiro Suzuki; H. Watanabe

2007-01-01

273

MHD pressure drop in ferritic pipes of fusion blankets  

Microsoft Academic Search

Magnetohydrodynamic flows in pipes of ferromagnetic material is an important issue for liquid metal blanket concepts using MANET as wall material. Fusion relevant magnetic fields of 4–8 T cause high pressure drop in the blanket header where a massive structure of ferromagnetic material exists. It is briefly outlined that in the blanket the reduction of pressure drop due to magnetic

J. Reimann; Leo Bühler; K. Messadek; R. Stieglitz

2003-01-01

274

Lightweight Insulated Footwear.  

National Technical Information Service (NTIS)

Compound formulations having good low temperature flexibility were developed for the outsole, upper and outer skin of the lightweight insulated boot. The proper insulation thickness for the entire boot was determined from foot insulation test data to prod...

R. A. Mazzeo

1971-01-01

275

Integrated first-wall\\/blanket\\/shield concept  

Microsoft Academic Search

An integrated first-wall\\/blanket\\/shield concept has evolved from the desire to improve the attractiveness and reduce the capital cost of fusion reactors. Design simplicity, improved safety, high performance, and reactor modularization are the key design factors in developing this concept. The main features and analysis of the concept are the subject of this paper.

Gohar

1986-01-01

276

The climatic impact of supervolcanic ash blankets  

NASA Astrophysics Data System (ADS)

Supervolcanoes are large caldera systems that can expel vast quantities of ash, volcanic gases in a single eruption, far larger than any recorded in recent history. These super-eruptions have been suggested as possible catalysts for long-term climate change and may be responsible for bottlenecks in human and animal populations. Here, we consider the previously neglected climatic effects of a continent-sized ash deposit with a high albedo and show that a decadal climate forcing is expected. We use a coupled atmosphere-ocean General Circulation Model (GCM) to simulate the effect of an ash blanket from Yellowstone volcano, USA, covering much of North America. Reflectivity measurements of dry volcanic ash show albedo values as high as snow, implying that the effects of an ash blanket would be severe. The modeling results indicate major disturbances to the climate, particularly to oscillatory patterns such as the El Niño Southern Oscillation (ENSO). Atmospheric disruptions would continue for decades after the eruption due to extended ash blanket longevity. The climatic response to an ash blanket is not significant enough to instigate a change to stadial periods at present day boundary conditions, though this is one of several impacts associated with a super-eruption which may induce long-term climatic change.

Jones, Morgan T.; Sparks, R. Stephen J.; Valdes, Paul J.

2007-11-01

277

The climatic impact of supervolcanic ash blankets  

NASA Astrophysics Data System (ADS)

Supervolcanoes are capable of ejecting 1000's of cubic kilometres of magmatic material in a single eruption, far surpassing anything recorded in human history. It has been postulated that these eruptions have acted as catalysts for long-term climate change and are responsible for bottlenecks in human and animal populations. Tephra deposits from a super-eruption are capable of covering an area the size of USA (~10,000,000 sq. km) with ash, destroying vegetation and considerably raising the surface albedo. Ecological responses to smaller eruptions show that recovery of flora takes over 15 years, while previous studies of ash blankets demonstrate sustained surface residence times. This suggests that a supervolcanic ash blanket would instigate a decadal climate response that would dominate in the aftermath of the effects of aerosols in the stratosphere. We use a coupled atmosphere-ocean General Circulation Model (GCM) to simulate the effect of an ash blanket from Yellowstone volcano, USA, and show that it causes major disruptions to the climate, particularly to oscillatory systems such as the El Niño Southern Oscillation (ENSO). The regional disturbance instigates a global response, with significant variations in surface temperatures, pressures and precipitation patterns. The ocean remains largely unaffected, though a marked increase in sea ice is seen in the North Atlantic. While the response to a supervolcanic ash blanket is predicted to be severe, the isolated effects of the disturbance are not significant enough to instigate long-term climate change at present day boundary conditions.

Jones, M. T.; Sparks, S. J.; Valdes, P. J.

2006-12-01

278

BWTR (Boiling Water Tokamak Reactor) blanket study  

Microsoft Academic Search

The NUWMAK design is a second generation reactor design study. It utilizes the experiences we obtained from UWMAK series designs, combined with recent development in plasma physics and aimed toward a more optimized reactor design. The blanket for NUWMAK is designed to minimize thermal cycling, provide internal thermal energy storage, eliminate the need for an intermediate loop, minimize tritium inventory,

D. K. Sze; C. W. Maynard; I. N. Sviatoslavsky; E. T. Cheng; C. C. Wang; J. Wrazel

1978-01-01

279

Partisanship Redefined: Why Blanket Primaries are Constitutional  

Microsoft Academic Search

In 2003, the Ninth Circuit Court of Appeals rendered a decision that would pave the way for drastic changes in Washington State's election process. In Democratic Party of Washington v. Reed, the court held that Washington's nearly seventy-year-old blanket primary was unconstitutional, and the Supreme Court declined to review the case. The Ninth Circuit professed to be bound by California

Deidra A. Foster

2005-01-01

280

Activation analysis of ITER blanket first wall  

Microsoft Academic Search

To analyze the activation of ITER blanket structural components, the authors have prepared the AUCDAS code that calculates changes in nuclide concentrations and radioactivity characteristics during neutron irradiation and during cooling. UCDAS takes into account all neutron reactions and decay types, the prepared library of constants contains nuclear data of nuclides from hydrogen to californium. A comparative analysis of the

A. Lopatkin; V. Muratov

1998-01-01

281

Methods to Enhance Blanket Power Density.  

National Technical Information Service (NTIS)

The overall objective of this task is to investigate the extent to which the power density in the FED/INTOR breeder blanket test modules can be enhanced by artificial means. Assuming a viable approach can be developed, it will allow advanced reactor blank...

P. Y. Hsu L. G. Miller T. S. Bohn G. A. Deis G. R. Longhurst

1982-01-01

282

Silver Teflon Blanket: LDEF Tray C-08.  

National Technical Information Service (NTIS)

A study of the Teflon blanket surface at the edge of tray C-08 illustrates the complexity of the microenvironments on the Long Duration Exposure Facility (LDEF). The distribution of particulate contaminants varied dramatically over a distance of half a ce...

E. R. Crutcher L. S. Nishimura K. J. Warner W. W. Wascher

1992-01-01

283

Blanket neutronics experiments at the lotus facility  

Microsoft Academic Search

LOTUS is a nuclear test facility designed for obtaining integral neutronics data for slab assemblies representative of fusion or hybrid blanket concepts. Its main element is a sealed, high intensity, D-T neutron generator. This paper presents some preliminary results from a set of spectrum measurements carried out with a NE-213 scintillator spectrometer. Neutron spectra are given for measurements made behind

Pierre-Andre Haldy; Anil Kumar; William R. Leo; Lawrence Green

1986-01-01

284

Removal of BTEX vapours from waste gas streams using silica aerogels of different hydrophobicity.  

PubMed

Silica aerogels are alternative adsorbents to activated carbon (AC) for the removal and the recovery of organic vapours from gas streams. The adsorption capacity measurements of different silica aerogels were done by mini-column method. Continuous adsorption measurements show that silica aerogels are excellent adsorbents of BTEX vapours from waste gas stream. Compared to the most used adsorbents, such as AC and silica gel, aerogels exhibit capacities which enormously exceed that of both commonly used adsorbents. By increasing the degree of hydrophobicity, aerogels become less effective, but they do not adsorb water vapour from gas stream. Silica monolith aerogels with different degrees of hydrophobicity by incorporating methyltrimethoxysilane (MTMS) or trimethylethoxysilane (TMES) in standard sol-gel synthesis were prepared. Excellent properties of aerogels, obtained with the sol-gel synthesis, were preserved with supercritical drying with CO(2). The degree of hydrophobicity of the aerogels was tested by measuring the contact angle (theta) of a water droplet with the aerogel surface. The aerogels were also characterised by FTIR, nitrogen sorption and DSC/TG measurements. PMID:19095355

Standeker, Suzana; Novak, Zoran; Knez, Zeljko

2008-11-11

285

Common insulating properties in insulating materials  

Microsoft Academic Search

Insulating materials exist in a variety of different forms, including gas, liquid, solid, and vacuum, and different forms of insulating materials have significantly different dielectric strengths and insulating properties. Power transmission\\/substation facilities for UHV AC and 500 kV DC power transmission and 500 kV underground power transmission facilities have been designed and constructed by taking advantage of the insulating properties

Shigemitsu Okabe; Naoki Hayakawa; Hiroshi Murase; Hiroyuki Hama; Hitoshi Okubo

2006-01-01

286

Synthesis, characterization, and modeling of hydrogen storage in carbon aerogels  

SciTech Connect

Carbon aerogels are a special class of open-cell foams with an ultrafine cell/pore size (<50 nm), high surface area (600-800 m{sup 2}/g), and a solid matrix composed of interconnected colloidal-like particles or fibers with characteristic diameters of 10 nm. These materials are usually synthesized from the sol-gel polymerization of resorcinol-formaldehyde or phenolic-furfural, followed by supercritical extraction of the solvent and pyrolysis in an inert atmosphere. The resultant aerogel has a nanocrystalline structure with micropores (<2 nm diameter) located within the solid matrix. Carbon aerogel monoliths can be prepared at densities ranging from 0.05-1.0 g/cm{sup 3}, leading to volumetric surface areas (> 500 m{sup 2}/cm{sup 3}) that are much larger than commercially available materials. This research program is directed at optimization of the aerogel structure for maximum hydrogen adsorption over a wide range of temperatures and pressures. Computer modeling of hydrogen adsorption at carbon surfaces was also examined.

Pekala, R.W.; Coronado, P.R.; Calef, D.F.

1995-04-01

287

AGING AND IODINE LOADING OF SILVER-FUNCTIONALIZED AEROGELS  

SciTech Connect

Engineered silver-functionalized silica aerogels are being investigated for their application in off-gas treatment at a used nuclear fuel reprocessing facility. Reprocessing will release several key volatile radionuclides, including iodine-129. To achieve regulatory compliance, iodine-129 must be removed from any off-gas stream prior to environmental discharge. Silver-functionalized aerogels have been demonstrated to have high iodine capture capacity, high porosity and potential for conversion into a waste form. Capture materials used in off-gas treatment may be exposed to a heated, high humidity, acidic gas stream for months. Extended exposure to this stream could affect sorbent performance. It was the aim of this study to evaluate what impacts might be observed when Ag0-functionalized aerogels prepared at Pacific Northwest National Laboratory were contacted with a dry air stream for up to 6 months and then used to adsorb iodine from a synthetic off-gas stream. Results demonstrate that there is some loss of iodine capture capacity caused by aging, but that this loss is not as marked as for aging of more traditional iodine sorbents, such as silver-impregnated mordenite. Specifically, aging silver-functionalized aerogel under a dry air stream for up to 6 months can decrease its iodine capacity from 41wt% to 32wt%.

Bruffey, Stephanie H [ORNL; Jubin, Robert Thomas [ORNL; Anderson, Kaara K [ORNL; Walker Jr, Joseph Franklin [ORNL

2013-01-01

288

Partially Hydrolized Alkoxysilanes as Precursors for Silica Aerogels.  

National Technical Information Service (NTIS)

The classical sol-gel process for synthesizing SiO sub 2 aerogels involves the hydrolysis condensation of tetraethyoxysilane (TEOS) and or teramethyoxysilane (TMOS) to produce a gel which can then be supercritically extracted to a low density, highly poro...

T. M. Tillotson L. W. Hrubesh I. M. Thomas

1988-01-01

289

Nitridation under ammonia of high surface area vanadium aerogels  

NASA Astrophysics Data System (ADS)

Vanadium pentoxide gels have been obtained from decavanadic acid prepared by ion exchange on a resin from ammonium metavanadate solution. The progressive removal of water by solvent exchange in supercritical conditions led to the formation of high surface area V2O5, 1.6H2O aerogels. Heat treatment under ammonia has been performed on these aerogels in the 450 900 °C temperature range. The oxide precursors and oxynitrides have been characterized by XRD, SEM, TGA, BET. Nitridation leads to divided oxynitride powders in which the fibrous structure of the aerogel is maintained. The use of both very low heating rates and high surface area aerogel precursors allows a higher rate and a lower threshold of nitridation than those reported in previous works. By adjusting the nitridation temperature, it has been possible to prepare oxynitrides with various nitrogen enrichment and vanadium valency states. Whatever the V(O,N) composition, the oxidation of the oxynitrides in air starts between 250 and 300 °C. This determines their potential use as chemical gas sensors at a maximum working temperature of 250 °C.

Merdrignac-Conanec, Odile; El Badraoui, Khadija; L'Haridon, Paul

2005-01-01

290

Porous silicon nanocrystals in a silica aerogel matrix.  

PubMed

Silicon nanoparticles of three types (oxide-terminated silicon nanospheres, micron-sized hydrogen-terminated porous silicon grains and micron-size oxide-terminated porous silicon grains) were incorporated into silica aerogels at the gel preparation stage. Samples with a wide range of concentrations were prepared, resulting in aerogels that were translucent (but weakly coloured) through to completely opaque for visible light over sample thicknesses of several millimetres. The photoluminescence of these composite materials and of silica aerogel without silicon inclusions was studied in vacuum and in the presence of molecular oxygen in order to determine whether there is any evidence for non-radiative energy transfer from the silicon triplet exciton state to molecular oxygen adsorbed at the silicon surface. No sensitivity to oxygen was observed from the nanoparticles which had partially H-terminated surfaces before incorporation, and so we conclude that the silicon surface has become substantially oxidised. Finally, the FTIR and Raman scattering spectra of the composites were studied in order to establish the presence of crystalline silicon; by taking the ratio of intensities of the silicon and aerogel Raman bands, we were able to obtain a quantitative measure of the silicon nanoparticle concentration independent of the degree of optical attenuation. PMID:22805684

Amonkosolpan, Jamaree; Wolverson, Daniel; Goller, Bernhard; Polisski, Sergej; Kovalev, Dmitry; Rollings, Matthew; Grogan, Michael D W; Birks, Timothy A

2012-07-17

291

Extreme synthesis and chemical doping of diamond aerogel  

NASA Astrophysics Data System (ADS)

Amorphous carbon aerogels have attracted much interest in recent years due to their low density, large intrinsic surface areas (>1000 m^2/g), large pore volume, low dielectric constant, and high strength. We use high-pressure (˜20 GPa) laser-heating (>600 C) within a diamond anvil cell (DAC) to convert the amorphous network of a low-density (40mg/cc) carbon aerogel into an ultrananocrystalline diamond aerogel. Photoluminescence spectroscopy and confocal time-correlated single-photon counting indicate the recovered material contains both negatively-charged and neutral nitrogen-vacancy (NV) complexes. Synchrotron scanning transmission x-ray microscopy (STXM) is used to compare the carbon electronic density-of-states of the amorphous starting material with the recovered diamond aerogel with ˜100 meV energy resolution. Finally, we use nanoscale secondary ion mass spectrometry to investigate doping of the resorcinol-formaldehyde starting material with the aim of chemically tuning heteroatomic point defects within this diamond material system.

Pauzauskie, Peter J.; Crowhurst, Jonathan C.; Worsley, Marcus A.; Laurence, Ted A.; Wang, Yinmin; Kilcoyne, A. L. D.; Weber, Peter K.; Willey, Trevor M.; Visbeck, Kenneth S.; Evans, William J.; Satcher, Joe H., Jr.

2010-03-01

292

Ultralow density silica aerogels by alcohol supercritical drying  

Microsoft Academic Search

Synthesis of ultralow density aerogels requires full transformation of diluted monomers into solid. Shrinkage during ageing and supercritical drying must be controlled as low as possible. Reported investigations deal with achievement in the optimisation of the two-step process parameters performed using classical acid and basic steps. Acid step involves the formation of partially hydrolysed and partially condensed silica mixture in

L. Kocon; F. Despetis; J. Phalippou

1998-01-01

293

Enhanced thermal characterization of silica aerogels through molecular dynamics simulation  

NASA Astrophysics Data System (ADS)

Porous structures of silica aerogels are generated using classical molecular dynamics, with the Tersoff potential, which has been re-parametrized for modeling silicon dioxides. This work demonstrates that this potential is superior to the widely used BKS potential in terms of characterizing the thermal conductivities of amorphous silica, by comparing the vibrational density of states with previous experimental studies. Aerogel samples of increasing densities are obtained through an expanding, heating and quenching process. Reverse non-equilibrium molecular dynamics is applied at each density to determine the thermal conductivity. A power-law fit of the results is found to accurately reflect the power-law variation found in experimental bulk aerogels. The results are also of the same order of magnitude as experimental bulk aerogels, but they are consistently higher. By analyzing the pore size distribution on different simulation length scales, we show that such a disparity is due to finite sizes of pores that can be represented, where increasing simulation length scales lead to an increase in the largest pore size that can be modeled.

Yeo, J. J.; Liu, Z. S.; Ng, T. Y.

2013-10-01

294

New organic aerogels based upon a phenolic-furfural reaction  

SciTech Connect

The aqueous polycondensation of (1) resorcinol with formaldehyde and (2) melamine with formaldehyde are two proven synthetic routes for the formation of organic aerogels. Recently, we have discovered a new type of organic aerogel based upon a phenolic-furfural (PF) reaction. This sol-gel polymerization has a major advantage over past approaches since it can be conducted in alcohol (e.g., 1-propanol), thereby eliminating the need for a solvent exchange step prior to supercritical drying from carbon dioxide. The resultant aerogels are dark brown in color and can be converted to a carbonized version upon pyrolysis in an inert atmosphere. BET surface areas of 350--600 m{sup 2}/g have been measured, and transmission electron microscopy reveals an interconnected structure of irregularly-shaped particles or platelets with {approximately}10 nm dimensions. Thermal conductivities as low as 0.015 W/m-K have been recorded for PF aerogels under ambient conditions. This paper describes the chemistry-structure-property relationships of these new materials in detail.

Hrubesh, L.W.

1994-09-01

295

Nuclear Magnetic Resonance Studies of Resorcinol-Formaldehyde Aerogels  

SciTech Connect

In this article we report a detailed study of resorcinol-formaldehyde (RF) aerogels prepared under different processing conditions, [resorcinol]/[catalyst] (R/C) ratios in the starting sol-gel solutions, using continuous flow hyperpolarized 129Xe NMR in combination with solid-state 13C and two-dimensional wide-line separation (2D-WISE) NMR techniques. The degree of polymerization and the mobility of the cross-linking functional groups in RF aerogels are examined and correlated with the R/C ratios. The origin of different adsorption regions is evaluated using both co-adsorption of chloroform and 2D EXSY 129Xe NMR. A hierarchical set of Xe exchange processes in RF aerogels is found using 2D EXSY 129Xe NMR. The exchange of Xe gas follows the sequence (from fastest to slowest): mesopores with free gas, gas in meso- and micro-pores, free gas with micropores, and, finally, among micropore sites. The volume-to-surface-area (Vg/S) ratios for aerogels are measured for the first time without the use of geometric models. The Vg/S parameter, which is related both to the geometry and the interconnectivity of the pore space, has been found to correlate strongly with the R/C ratio and exhibits an unusually large span: an increase in the R/C ratio from 50 to 500 results in about a 5-fold rise in Vg/S.

Moudrakovski, Igor L.; Ratcliffe, C I.; Ripmeester, J A.; Wang, Li Q.; Exarhos, Gregory J.; Baumann, T; Satcher, J H.

2005-06-09

296

Porous silicon nanocrystals in a silica aerogel matrix  

NASA Astrophysics Data System (ADS)

Silicon nanoparticles of three types (oxide-terminated silicon nanospheres, micron-sized hydrogen-terminated porous silicon grains and micron-size oxide-terminated porous silicon grains) were incorporated into silica aerogels at the gel preparation stage. Samples with a wide range of concentrations were prepared, resulting in aerogels that were translucent (but weakly coloured) through to completely opaque for visible light over sample thicknesses of several millimetres. The photoluminescence of these composite materials and of silica aerogel without silicon inclusions was studied in vacuum and in the presence of molecular oxygen in order to determine whether there is any evidence for non-radiative energy transfer from the silicon triplet exciton state to molecular oxygen adsorbed at the silicon surface. No sensitivity to oxygen was observed from the nanoparticles which had partially H-terminated surfaces before incorporation, and so we conclude that the silicon surface has become substantially oxidised. Finally, the FTIR and Raman scattering spectra of the composites were studied in order to establish the presence of crystalline silicon; by taking the ratio of intensities of the silicon and aerogel Raman bands, we were able to obtain a quantitative measure of the silicon nanoparticle concentration independent of the degree of optical attenuation.

Amonkosolpan, Jamaree; Wolverson, Daniel; Goller, Bernhard; Polisski, Sergej; Kovalev, Dmitry; Rollings, Matthew; Grogan, Michael D. W.; Birks, Timothy A.

2012-07-01

297

Liquid-vapor critical behavior in silica aerogel  

Microsoft Academic Search

Fluids in porous media provide a testing ground for the effects of disorder and confinement on phase transitions and critical phenomena. Specifically, highly porous silica aerogel with its tenuous solid structure has allowed low temperature physicists to probe the effect of dilute fixed impurities on both the 4He superfluid transition and the 3He superfluid transition. Both systems have yielded exciting

Tobias Kent Herman

2005-01-01

298

Cherenkov detector of 90Sr based on aerogel as radiator  

Microsoft Academic Search

90Sr is a highly radiotoxic fission product, which may pollute the environment following an accident in a nuclear power plant. It is a pure ? emitter and thus difficult to detect by standard methods. Recent progress in silica aerogel production, as well as the new multianode photomultiplier tubes (PMTs), offer possibilities for the detection of 90Sr, based on Cherenkov radiation

R. Pestotnik; S. Korpar; P. Krizan; R. Dolenec

2008-01-01

299

Mechanically Strong Lightweight Materials for Aerospace Applications (x-aerogels).  

National Technical Information Service (NTIS)

The X-Aerogel is a new NASA-developed strong lightweight material made by reacting the mesoporous surfaces of 3-D networks of inorganic nanoparticles with polymeric crosslinkers. Since the relative amount of the crosslinker and the backbone are comparable...

N. Leventis

2005-01-01

300

A Silica Aerogel Counter for Large-Acceptance Hadron Detection  

Microsoft Academic Search

In order to study the feasibility of large scale multicell counters, two prototypes with respective detection area 80 × 40 cm2 and 65 × 31 cm2 were constructed. The Cerenkov light produced in silica aerogel of refractive index n = 1.03 and diffused in a well optimized box was detected with five quantacon photomultipliers. Results of beam tests concerning the

C. Arnault; P. L. Barberis; G. Bassompierre; W. Burkhardt; G. Coignet; U. Dosselli; P. Heusse; F. Montanet; M. Schneegans

1981-01-01

301

Adsorptive crystallization of benzoic acid in aerogels from supercritical solutions  

Microsoft Academic Search

In this work, adsorption and crystallization of benzoic acid in different porous carriers (silica aerogel, MCM41, Trisopor glass, zeolite) from supercritical CO2 solutions is studied. The main purpose is to reveal the influence of the adsorptive properties of the carrier on the crystallization behavior of the solute. Therefore, both adsorption and crystallization processes are studied as a function of carrier's

B. S. K. Gorle; I. Smirnova; W. Arlt

2010-01-01

302

Liquid Metal Compatibility Issues for Test Blanket Modules  

SciTech Connect

Liquid metal compatibility issues are being investigated for two different test blanket modules involving either Li or Pb-17 at.%Li. A solution to the magnetohydrodynamic (MHD) problem for the V-Li concept may be attainable using multi-layer coatings or a flow channel insert with vanadium in contact with the flowing Li instead of a ceramic insulating layer. These strategies rely on the expected excellent compatibility of vanadium alloys which is being further investigated. For systems using Pb-17Li, capsule testing of SiC and various alloys is being conducted. Monolithic SiC specimens exposed for 1000 h in Pb-Li at 800 and 1100 {sup o}C showed no mass change after cleaning and no detectable increase in the Si content of the Pb-Li after the test. In order to investigate the behavior of corrosion resistant aluminide coatings, initial capsule testing at 700 {sup o}C has been used to establish baseline dissolution rates for 316 stainless steel, FeCrAl, Fe{sub 3}Al and NiAl. The samples containing Al showed significantly less mass loss than 316 stainless steel, suggesting that aluminide coatings will be beneficial in this temperature range.

Pint, Bruce A [ORNL; Moser, Jeremy L [ORNL; Tortorelli, Peter F [ORNL

2006-01-01

303

Characterization of aerogel and Photomultiplier Tubes for the 12-GeV Hall C Kaon Aerogel Detector at Jefferson Lab  

NASA Astrophysics Data System (ADS)

Thomas Jefferson National Accelerator Facility's upgrade from 6-GeV to 12-GeV beam energy requires a new magnetic spectrometer for Hall C. At 6 GeV the High Momentum Spectrometer (HMS) made use of an aerogel threshold Cherenkov detector for particle identification of p/K/p. The HMS is not designed to operate at momenta greater than 7 GeV/c, instead a Super High Momentum Spectrometer (SHMS) will be constructed. An aerogel threshold Cherenkov detector needs to be included in the new spectrometer as well. Pions, kaons and protons of sufficient velocity produce Cherenkov radiation when passing through media with low indices of refraction. Aerogels with n = 1.020 and n = 1.030 will be used for p/K/p separation. A diffusion box, lined with millipore, will collect the light from the Cherenkov radiation. Photomultiplier tubes (PMTs) will then detect the light and convert the photons into an electrical signal that electronics will then be able to interpret. This presentation will show the dependence of the aerogel's signal strength on thickness of stack as well as the PMTs' gain dependence on high voltage.

Wood, Kevin

2011-10-01

304

Aerogel tracks made by impacts of glycine: Implications for formation of bulbous tracks in aerogel and the Stardust mission  

NASA Astrophysics Data System (ADS)

Impacts of small particles of soda-lime glass and glycine onto low density aerogel are reported. The aerogel had a quality similar to the flight aerogels carried by the NASA Stardust mission that collected cometary dust during a flyby of comet 81P/Wild 2 in 2004. The types of track formed in the aerogel by the impacts of the soda-lime glass and glycine are shown to be different, both qualitatively and quantitatively. For example, the soda-lime glass tracks have a carrot-like appearance and are relatively long and slender (width to length ratio <0.11), whereas the glycine tracks consist of bulbous cavities (width to length ratio >0.26). In consequence, the glycine particles would be underestimated in diameter by a factor of 1.7-3.2, if the glycine tracks were analyzed using the soda-lime glass calibration and density. This implies that a single calibration for impacting particle size based on track properties, as previously used by Stardust to obtain cometary dust particle size, is inappropriate.

Nixon, Adam; Burchell, Mark J.; Price, Mark C.; Kearsley, Anton T.; Jones, Steven

2012-04-01

305

Thermal performance of various multilayer insulation systems below 80K  

SciTech Connect

The SSC collider dipole cryostat consists of a vacuum shell operating at room temperature, two thermal shields operating near 80K and 20K respectively, and the superconducting magnet assembly operating near 4K. The cryostat design incorporates multilayer insulation (MLI) blankets to limit radiant heat transfer into the 80K and 20K thermal shields. Also, an MLI blanket is used to impede heat transfer through residual gas conduction into the 4K superconducting magnet assembly. A measurement facility at Fermilab has been used to experimentally optimize the thermal insulation system for the dipole cryostat. Previous thermal measurements have been used to define the 80K MLI system configuration and verify system performance. With the 80K MLI system defined, the current effort has focused on experimentally defining the optimum insulation scheme for the 20K thermal shield. The SSC design specification requires that radiant heat transfer be limited to 0.093 W/m[sup 2] at an insulating vacuum of 10[sup [minus]6]torr.

Boroski, W.N.; Nicol, T.H.; Schoo, C.J.

1992-04-01

306

Thermal performance of various multilayer insulation systems below 80K  

SciTech Connect

The SSC collider dipole cryostat consists of a vacuum shell operating at room temperature, two thermal shields operating near 80K and 20K respectively, and the superconducting magnet assembly operating near 4K. The cryostat design incorporates multilayer insulation (MLI) blankets to limit radiant heat transfer into the 80K and 20K thermal shields. Also, an MLI blanket is used to impede heat transfer through residual gas conduction into the 4K superconducting magnet assembly. A measurement facility at Fermilab has been used to experimentally optimize the thermal insulation system for the dipole cryostat. Previous thermal measurements have been used to define the 80K MLI system configuration and verify system performance. With the 80K MLI system defined, the current effort has focused on experimentally defining the optimum insulation scheme for the 20K thermal shield. The SSC design specification requires that radiant heat transfer be limited to 0.093 W/m{sup 2} at an insulating vacuum of 10{sup {minus}6}torr.

Boroski, W.N.; Nicol, T.H.; Schoo, C.J.

1992-04-01

307

Calcium silicate insulation structure  

DOEpatents

An insulative structure including a powder-filled evacuated casing utilizes a quantity of finely divided synthetic calcium silicate having a relatively high surface area. The resultant structure-provides superior thermal insulating characteristics over a broad temperature range and is particularly well-suited as a panel for a refrigerator or freezer or the insulative barrier for a cooler or a insulated bottle.

Kollie, Thomas G. (Oak Ridge, TN); Lauf, Robert J. (Oak Ridge, TN)

1995-01-01

308

Multiple density layered insulator  

DOEpatents

A multiple density layered insulator for use with a laser is disclosed which provides at least two different insulation materials for a laser discharge tube, where the two insulation materials have different thermoconductivities. The multiple layer insulation materials provide for improved thermoconductivity capability for improved laser operation. 4 figs.

Alger, T.W.

1994-09-06

309

Vibration and Thermal Cycling Effects on Bulk-fill Insulation Materials for Cryogenic Tanks  

NASA Astrophysics Data System (ADS)

Large-scale (1,000,000 liters or more) cryogenic storage tanks are typically perlite-insulated double-walled vessels. Associated problems with perlite, such as mechanical compaction and settling, could be greatly reduced by using newer bulk-fill materials such as glass bubbles or aerogel beads. Using the newer materials should translate to lower life cycle costs and improved system reliability. NASA Kennedy Space Center is leveraging its experience in the areas of materials development, insulation testing, and cryogenic systems design to develop an insulation retrofit option that will meet both industry and NASA requirements. A custom 10-liter dewar test apparatus, developed by the KSC Cryogenics Test Laboratory, was used to determine the vibration and thermal cycling effects on different bulk-fill insulation materials for cryogenic tanks. The testing included liquid-nitrogen boiloff testing and thermal cycling (with vibration) of a number of test dewars. Test results show that glass bubbles have better thermal performance and less mechanical compaction compared to perlite powder. The higher cost of the bulk material should be offset by reduced commodity loss from boiloff and improvements in material handling, evacuation, and vacuum retention. The long-term problem with settling and compaction of perlite should also be eliminated. Aerogel beads are superior for the no-vacuum condition and can now be considered in some applications. Further studies on large-scale systems are presently being pursued.

Fesmire, J. E.; Augustynowicz, S. D.; Nagy, Z. F.; Sojourner, S. J.; Morris, D. L.

2006-04-01

310

Impact of the fabrication method on the physicochemical properties of carbon nanotube-based aerogels  

Microsoft Academic Search

The preparation and characterization of porous multi-walled carbon nanotube-based aerogels is reported here. Aerogels with varying nanotube content (25–100wt.%) were fabricated by a combination of flash freezing\\/lyophilization process, using poly(vinyl alcohol) as a structural binder. The resulting aerogels were characterized by SEM imaging and nitrogen porosimetry. The specific surface area as well as the thermal behavior of the carbon nanotube-based

Theodosis Skaltsas; Georgios Avgouropoulos; Dimitrios Tasis

2011-01-01

311

Removal of bromide and iodide anions from drinking water by silver-activated carbon aerogels  

Microsoft Academic Search

The aim of this study is to analyze the use of Ag-doped activated carbon aerogels for bromide and iodide removal from drinking water and to study how the activation of Ag-doped aerogels affects their behavior. It has been observed that the carbonization treatment and activation process of Ag-doped aerogels increased the surface area value (SN2), whereas the volume of meso-(V2)

M. Sánchez-Polo; J. Rivera-Utrilla; E. Salhi; U. von Gunten

2006-01-01

312

Luminescent studies of fluorescent chromophore-doped silica aerogels for flat panel display applications  

SciTech Connect

The remarkable optical and electronic properties of doped and undoped silica aerogels establish their utility as unique, mulitfunctional host materials for fluorescent dyes and other luminescent materials for display and imaging applications. We present results on the photoluminescence, absorption, and photoluminescence excitation spectra of undoped silica aerogels and aerogels doped with Er{sup 3+}, rhodamine 6G (R6G), and fluorescein. 4 refs., 12 figs.

Glauser, S.A.C. [California Univ., Davis, CA (United States). Dept. of Applied Science; Lee, H.W.H. [Lawrence Livermore National Lab., CA (United States)

1997-04-01

313

The effects of physical and chemical interactions in the formation of cellulose aerogels  

Microsoft Academic Search

Aerogels are low density materials which are produced from wet gels, and find a variety of potential uses. The relative importance\\u000a of shape\\/geometry and self-association of the starting materials for the production of aerogels is studied herein. Aerogels\\u000a were produced from microcrystalline cellulose (MCC) and its functionalized analog, carboxymethyl cellulose (CMC). With increasing\\u000a functionalization, CMC gains the potential for self-association,

Warut SurapolchaiDavid; David A. Schiraldi

2010-01-01

314

Neutronics Assessment of Molten Salt Breeding Blanket Design Options  

SciTech Connect

Neutronics assessment has been performed for molten salt breeding blanket design options that can be utilized in fusion power plants. The concepts evaluated are a self-cooled Flinabe blanket with Be multiplier and dual-coolant blankets with He-cooled FW and structure. Three different molten salts were considered including the high melting point Flibe, a low melting point Flibe, and Flinabe. The same TBR can be achieved with a thinner self-cooled blanket compared to the dual-coolant blanket. A thicker Be zone is required in designs with Flinabe. The overall TBR will be {approx}1.07 based on 3-D calculations without breeding in the divertor region. Using Be yields higher blanket energy multiplication than obtainable with Pb. A modest amount of tritium is produced in the Be ({approx}3 kg) over the blanket lifetime of {approx}3 FPY. Using He gas in the dual-coolant blanket results in about a factor of 2 lower blanket shielding effectiveness. We show that it is possible to ensure that the shield is a lifetime component, the vacuum vessel is reweldable, and the magnets are adequately shielded. We conclude that molten salt blankets can be designed for fusion power plants with neutronics requirements such as adequate tritium breeding and shielding being satisfied.

Sawan, M.E. [University of Wisconsin-Madison (United States); Malang, S. [Fusion Nuclear Technology Consulting (United States); Wong, C.P.C. [General Atomics (United States); Youssef, M.Z. [University of California-Los Angeles (United States)

2005-04-15

315

UV Induced Insulator Flashover  

Microsoft Academic Search

Insulators are critical components in high-energy, pulsed power systems. It is known that the vacuum surface of the insulator will flashover when illuminated by ultraviolet (UV) radiation depending on the insulator material, insulator cone angle, applied voltage and insulator short-history. A testbed comprised of an excimer laser (KrF, 248 nm, ~2 MW\\/cm2, 30 ns FWHM,), a vacuum chamber (low 1.0E-6

J. B. Javedani; T. L. Houck; B. T. Kelly; D. A. Lahowe; M. D. Shirk; D. A. Goerz

2008-01-01

316

Leftover Superfluid 4He in Aerogel and Its Crystallization by Cooling  

NASA Astrophysics Data System (ADS)

Using a variable volume cell, we were able to crystallize 4He in aerogels at a constant temperature. The entire crystallization process was monitored visually owing to the transparency of the aerogel. Two different crystallization processes of 4He in aerogels were observed: creep at high temperatures and avalanche at low temperatures. In a 96 % porosity aerogel, we noticed that 4He remained liquid in some parts of the cell even though other parts of the aerogel were completely crystallized. Once such a situation was formed, the application of additional pressure did not further crystallize the liquid. This is presumably because a supply path of 4He atoms from the bulk crystal was blocked by the crystals in the aerogel. This leftover liquid, however, was found to begin to crystallize via avalanches when cooled below a particular temperature. If the crystallization pressure in aerogel is temperature independent at low temperatures as the bulk crystallization pressure, the crystallization by cooling is rather unusual. Possible explanations would be a decrease of the crystallization pressure in aerogel in the low temperature region, or the supersolidity of crystals in aerogel playing some role in mass transport.

Matsuda, Hirofumi; Ochi, Aguri; Isozaki, Rei; Nomura, Ryuji; Okuda, Yuichi

2013-05-01

317

Europium-Containing Organic Gels and Organic and Carbon Aerogels. Preparation and Initial Applications in Catalysis  

Microsoft Academic Search

Summary.  We prepared organic gels and organic and carbon aerogels doped with europium through sol–gel processes. Eu-gels were prepared\\u000a by sol–gel polymerization of the potassium salt of 2,4-dihydroxybenzoic acid with formaldehyde followed by ion-exchange with\\u000a Eu(OTf)3. Eu–organic aerogels were obtained after CO2 supercritical drying of the gels and Eu–carbon aerogels were obtained by pyrolysing the organic aerogels. The Eu-gels containing\\u000a 12%

Sandra Martínez; Laura Martín; Elies Molins; Marcial Moreno-Mañas; Anna Roig; Adelina Vallribera

2006-01-01

318

Enhanced thermal transport in carbon aerogel nanocomposites containing double-walled carbon nanotubes  

NASA Astrophysics Data System (ADS)

We report thermal conductivity measurements of a carbon aerogel nanocomposite containing double-walled carbon nanotubes. The nanocomposites were prepared by the sol-gel polymerization of resorcinol with formaldehyde in aqueous suspension containing a surfactant-stabilized dispersion of double-walled carbon nanotubes. Subsequent drying and pyrolysis resulted in free-standing monolithic carbon aerogel nanocomposites with uniform dispersions of carbon nanotubes. The monoliths were characterized by high-resolution scanning electron microscopy and thermal conductivity measurements via the transient hot-wire method. Enhanced thermal conductivities were observed for carbon aerogel nanocomposites relative to pristine carbon aerogels. The details of these results are discussed in comparison with theory and literature.

Worsley, Marcus A.; Satcher, Joe H.; Baumann, Theodore F.

2009-04-01

319

A sol-gel route to very high porosity silica aerogels  

SciTech Connect

This report discusses the preparation and characterization of very high porosity silica aerogels. The data presented here suggests a microstructure for the very high porosity silica aerogel that differs from the bead-like structure proposed for single-step, base catalysed TMOS aerogels. The data is consistent with an interlinked polymer chain-like structure, with an average chain diameter of 2-3nm and an average chain length >15nm. The increased transparency of these new aerogels also indicates that they have very small particles and uniform pores less than 50nm.

Hrubesh, L.W.; Tillotson, T.M.; Poco, J.F.

1991-02-01

320

Dissolution rate enhancement by adsorption of poorly soluble drugs on hydrophilic silica aerogels.  

PubMed

The aim of this work is to evaluate the feasibility of hydrophilic silica aerogels as drug carriers and to investigate the influence of the aerogels properties on the release rate of poorly water-soluble drugs. Hydrophilic silica aerogels of different densities were loaded with two model drugs, ketoprofen and griseofulvin, by adsorption from their solution in supercritical CO2. It is demonstrated that up to 30 wt% of ketoprofen and 5.4 wt% of griseofulvin can be deposited on hydrophilic aerogels through physical adsorption. The obtained drug-aerogel formulations were characterized by IR- and UV-spectroscopy, X-ray diffraction and scanning electron microscopy. Release kinetics of both drugs were studied in vitro. The release rate of ketoprofen from the drug-aerogel formulation is much faster than that of the corresponding crystalline drugs. The release rate of ketoprofen increases in 500% and that of griseofulvin in 450%, respectively. The reasons for the release enhancement are the enlarged specific surface area of drugs by adsorption on aerogels compared to their crystalline form and the immediate collapse of aerogel network in aqueous media. The dissolution rate of poorly water soluble drugs can be significantly enhanced by adsorption on highly porous hydrophilic silica aerogels. PMID:15581080

Smirnova, Irina; Suttiruengwong, Supakij; Seiler, Matthias; Arlt, Wolfgang

2004-11-01

321

A Precambrian proximal ejecta blanket from Scotland  

NASA Astrophysics Data System (ADS)

Ejecta blankets around impact craters are rarely preserved onEarth. Although impact craters are ubiquitous on solid bodiesthroughout the solar system, on Earth they are rapidly effaced,and few records exist of the processes that occur during emplacementof ejecta. The Stac Fada Member of the Precambrian Stoer Groupin Scotland has previously been described as volcanic in origin.However, shocked quartz and biotite provide evidence for high-pressureshock metamorphism, while chromium isotope values and elevatedabundances of platinum group metals and siderophile elementsindicate addition of meteoritic material. Thus, the unit isreinterpreted here as having an impact origin. The ejecta blanketreaches >20 m in thickness and contains abundant dark green,vesicular, devitrified glass fragments. Field observations suggestthat the deposit was emplaced as a single fluidized flow thatformed as a result of an impact into water-saturated sedimentarystrata. The continental geological setting and presence of groundwatermake this deposit an analogue for Martian fluidized ejecta blankets.

Amor, Kenneth; Hesselbo, Stephen P.; Porcelli, Don; Thackrey, Scott; Parnell, John

2008-04-01

322

Neutronics integral experiments of annular blanket system simulating tokamak reactor configuration  

Microsoft Academic Search

Neutronics experiments on annular blanker systems that use a pseudoline source are performed. Deuterium-tritium neutron sources are set at the center of the inner cavity of the annular blanket system, and the pseudoline source is obtained by oscillating the annular blanket system back and forth in a 2-m span. Three annular blanket configurations are examined: the reference blanket, a blanket

Chikara Konno; Yukio Oyama; Fujio Maekawa

1995-01-01

323

Improving MRI magnet thermal performance using variable density multilayer insulation  

NASA Astrophysics Data System (ADS)

Careful techniques for multilayer insulation (MLI) wrapping of MRI magnet cryostats have been shown to be critical in establishing a net Zero Helium Boil Off. Traditional MLI together with a cryocooler have been used in such 'Zero Boil Off' cryostats for many years. This paper discusses how the evolution in design of MRI magnet cryostats is challenging traditional MLI. By looking at the fundamental design equations for MLI, new insight can be gained into improving the design using variable density insulation. A new, proprietary method for creating variable density in MLI was devised and the resulting blankets were applied to MRI magnets. Results show a 10% improvement in insulation performance and a 42% improvement in material cost of the MLI. This new Variable Density MLI also holds promise for application to other liquid helium cryostats.

Zia, Jalal; Rutherford, William; Einziger, William

2012-06-01

324

Identifying Markov Blankets Using Lasso Estimation  

Microsoft Academic Search

\\u000a Determining the causal relation among attributes in a domain is a key task in data mining and knowledge discovery. The Minimum\\u000a Message Length (MML) principle has demonstrated its ability in discovering linear causal models from training data. To explore\\u000a the ways to improve efficiency, this paper proposes a novel Markov Blanket identification algorithm based on the Lasso estimator.\\u000a For each

Gang Li; Honghua Dai; Yiqing Tu

2004-01-01

325

Progress on the TAURO blanket system  

Microsoft Academic Search

TAURO is a self-cooled Pb?17Li blanket for Fusion Power Reactors (FPRs) using SiCf\\/SiC composites structures. It has been developed with the objective to achieve both passive safety and high thermal efficiency. The Pb?17Li outlet temperature exceeds 850°C. A Brayton cycle is envisaged for power conversion and the possibility of hydrogen production is addressed. This paper recalls the main features of

H Golfier; G Aiello; M Futterer; L Giancarli; A Li-Puma; Y Poitevin; J Szczepanski

2002-01-01

326

Nuclear Analysis of an ITER Blanket Module  

NASA Astrophysics Data System (ADS)

ITER blanket system is the reactor's plasma-facing component, it is mainly devoted to provide the thermal and nuclear shielding of the Vacuum Vessel and external ITER components, being intended also to act as plasma limiter. It consists of 440 individual modules which are located in the inboard, upper and outboard regions of the reactor. In this paper attention has been focused on to a single outboard blanket module located in the equatorial zone, whose nuclear response under irradiation has been investigated following a numerical approach based on the Monte Carlo method and adopting the MCNP5 code. The main features of this blanket module nuclear behaviour have been determined, paying particular attention to energy and spatial distribution of the neutron flux and deposited nuclear power together with the spatial distribution of its volumetric density. Moreover, the neutronic damage of the structural material has also been investigated through the evaluation of displacement per atom and helium and hydrogen production rates. Finally, an activation analysis has been performed with FISPACT inventory code using, as input, the evaluated neutron spectrum to assess the module specific activity and contact dose rate after irradiation under a specific operating scenario.

Chiovaro, P.; Di Maio, P. A.; Parrinello, V.

2013-08-01

327

An overview of dual coolant Pb-17Li breeder first wall and blanket concept development for the US ITER-TBM design  

SciTech Connect

An attractive blanket concept for the fusion reactor is the dual coolant Pb-17Li liquid (DCLL) breeder design. Reduced activation ferritic steel (RAFS) is used as the structural material. Helium is used to cool the first wall and blanket structure, and the self-cooled breeder Pb-17Li is circulated for power conversion and for tritium breeding. A SiCf/SiC composite insert is used as the magnetohydrodynamic (MHD) insulation to reduce the impact from the MHD pressure drop of the circulating Pb-17Li and as the thermal insulator to separate the high temperature Pb-17Li from the helium cooled RAFS structure. For the reference tokamak power reactor design, this blanket concept has the potential of satisfying the design limits of RAFS while allowing the feasibility of having a high Pb-17Li outlet temperature of 700 C. We have identified critical issues for the concept, some of which include the first wall design, the assessment of MHD effects with the SiC-composite flow coolant insert, and the extraction and control of the bred tritium from the Pb-17Li breeder. R&D programs have been proposed to address these issues. At the same time we have proposed a test plan for the DCLL ITER-Test Blanket Module program.

Wong, C C; Malang, S; Sawan, M; Dagher, M; Smolentsev, S; Merrill, B; Youssef, M; Reyes, S; Sze, D D; Morley, N B; Sharafat, S; Calderoni, P; Sviatoslavsky, G; Kurtz, R; Fogarty, P; Zinkle, S; Abdou, M

2005-05-13

328

Neutronic optimization of solid breeder blankets for STARFIRE design  

SciTech Connect

Extensive neutronic tradeoff studies were carried out to define and optimize the neutronic performance of the different solid breeder options for the STARFIRE blanket design. A set of criteria were employed to select the potential blanket materials. The basic criteria include the neutronic performance, tritium-release characteristics, material compatibility, and chemical stability. Three blanket options were analyzed. The first option is based on separate zones for each basic blanket function where the neutron multiplier is kept in a separate zone. The second option is a heterogeneous blanket type with two tritium breeder zones. In the first zone the tritium breeder is assembled in a neutron multiplier matrix behind the first wall while the second zone has a neutron moderator matrix instead of the neutron multiplier. The third blanket option is similar to the second concept except the tritium breeder and the neutron multiplier form a homogeneous mixture.

Gohar, Y.; Abdou, M.A.

1980-01-01

329

Passively safe tandem mirror fusion blanket afterheat thermal analysis  

Microsoft Academic Search

This paper presents results of the thermal analysis of an inherently safe blanket design concept. The blanket is composed of V-15Cr-5Ti structure with lithium for tritium breeding, beryllium for neutron multiplication and SiC for neutron reflection and moderation. Cooling of the blanket is provided by flowing helium gas which is assumed to be unavailable for heat transfer during the accident.

J. K. Garner; C. F. Carson; R. H. Whitley; J. D. Gordon

1987-01-01

330

FWBS Program element II: Blanket and shield testing  

Microsoft Academic Search

The First Wall\\/Blanket\\/Shield (FWBS) Program has the goal to provide the development and testing of FWBS systems for magnetic fusion reactors. Program Element II of this program is to develop the thermal-hydraulic and thermomechanical data base for blanket and shield components. The critical blanket\\/shield data needs were identified, alternate techniques to simulate fusion neutron bulk heating were evaluated, and a

K. R. Schultz; A. R. Veca

1983-01-01

331

Focusing Aerogel RICH for particle identification and momentum measurement  

NASA Astrophysics Data System (ADS)

The work is devoted to the development of the Focusing Aerogel RICH (FARICH). The option of the forward RICH for the SuperB project in Italy is presented. It features an aerogel-NaF radiator and MCP photodetectors. Monte Carlo simulation predicts the ?/ K separation at the level better than 3? from 0.2 to 7 GeV/c, the ?/? separation—from 0.13 to 1.3 GeV/c, and the kaon momentum measurement with an accuracy of about 1% at 1 GeV/c. FARICH for the Super Charm-Tau Factory project in Novosibirsk is proposed. Monte Carlo simulation predicts ?/? separation at the level better than 3? for a momentum from 0.3 to 1.7 GeV/c. A prototype will be tested on the new electron test beam facility at VEPP-4M collider.

Barnyakov, A. Yu.; Barnyakov, M. Yu.; Basok, I. Yu.; Blinov, V. E.; Bobrovnikov, V. S.; Borodenko, A. A.; Buzykaev, A. R.; Gulevich, V. V.; Danilyuk, A. F.; Kononov, S. A.; Kravchenko, E. A.; Kuyanov, I. A.; Onuchin, A. P.; Ovtin, I. V.

2011-05-01

332

Electrochemical behavior of carbon aerogels derived from different precursors  

SciTech Connect

The ability to tailor the structure and properties of porous carbons has led to their increased use as electrodes in energy storage devices. Our research focuses on the synthesis and characterization of carbon aerogels for use in electrochemical double layer capacitors. Carbon aerogels are formed from the sol-gel polymerization of (1) resorcinol-formaldehyde or (2) phenolic-furfural, followed by supercritical drying from carbon dioxide, and subsequent pyrolysis in an inert atmosphere. These materials can be produced as monoliths, composites, thin films, powders, or microspheres. In all cases, the areogels have an open-cell structure with an ultrafine pore size (<100 nm), high surface area (400-1 100 m{sup 2}/g), and a solid matrix composed of interconnected particles, fibers, or platelets with characteristic dimensions of 10 nm. This paper examines the effects of the carbon precursor and processing conditions on electrochemical performance in aqueous and organic electrolytes.

Pekala, R.W.; Alviso, C.T.; Nielson, J.K.; Tran, T.D. [Lawrence Livermore National Lab., CA (United States); Reynolds, G.M.; Dresshaus, M.S. [Massachusetts Inst. of Tech., Cambridge, MA (United States). Dept. of Physics

1995-04-01

333

A comparison of mechanical properties and scaling law relationships for silica aerogels and their organic counterparts  

SciTech Connect

Aerogels are a special class of open-cell foams derived from the supercritical extraction of highly crosslinked, inorganic or organic gels. The resultant materials have ultrafine cell/pore sizes (< 100 nm), high surface areas (350--1000m{sup 2}/g), and a microstructure composed of interconnected colloidal-like particles or polymeric chains with characteristic diameters of 10 nm. TEM and SAXS show that this microstructure is sensitive to variations in processing conditions that influence crosslinking chemistry and growth processes prior to gelation. Traditional silica aerogels are prepared via the hydrolysis and condensation of tetramethoxy silane (TMOS) or tetraethoxy silane (TEOS). Factors such as pH and the (H{sub 2}O)/(TMOS) ratio affect the microstructure of the dried aerogel. It is generally accepted that polymeric' silica aerogels result from acid catalysis while colloidal'silica aerogels result from base catalysis. Recently, Hrubesh and Tillotson developed a new condensed silica' procedure for obtaining silica aerogels with densities as low as 0.004g/cc, i.e. only 3{times} the density of air. Organic aerogels are formed from the aqueous, polycondensation of (1) resorcinol/formaldehyde or (2) melamine/formaldehyde. The microstructure of the resorcinol-formaldehyde (RF) aerogels is dictated by the amount of base catalyst used in the sol-gel polymerization. In addition, these materials can be pyrolyzed in an inert atmosphere to form vitreous carbon aerogels. Melamine- formaldehyde (MF) aerogels that are both colorless and transparent are only formed under acidic conditions (i.e. pH = 1--2). In this paper, the microstructural dependence and scaling law relationships for the compressive modulus of silica, carbon, RF, and MF aerogels will be discussed in detail. 17 refs., 1 fig.

Pekala, R.W.; Hrubesh, L.W.; Tillotson, T.M.; Alviso, C.T.; Poco, J.F.; LeMay, J.D.

1990-08-01

334

Thermal performance measurements of a 100 percent polyester MLI (multilayer insulation) system for the Superconducting Super Collider  

Microsoft Academic Search

Thermal performance measurements of a 100 percent polyester multilayer insulation (MLI) system for the Superconducting Super Collider (SSC) were conducted in a Heat Leak Test Facility (HLTF) under three experimental test arrangements. Each experiment measured the thermal performance of a 32-layer MLI blanket instrumented with twenty foil sensors to measure interstitial layer temperatures. Heat leak values and sensor temperatures were

W. N. Boroski; J. D. Gonczy; R. C. Niemann

1989-01-01

335

Synthesis and properties of vanadium oxide aerogel films. Technical report, 1 June 1995-31 May 1996  

Microsoft Academic Search

The fine colloid size, high surface area and controllable density of vanadium oxide aerogels make these materials interesting candidates for lithium insertion electrodes. Thin films of vanadium oxide aerogels were prepared using an alkoxide precursor sol and supercritical drying with CO2. Film preparation methods included spin coating of fine aerogel particles suspended in a solvent and dip coating of the

H. P. Wong; B. Dunn; K. Salloux; F. Chaput; M. W. Breiter

1996-01-01

336

Porous structure of organic and carbon aerogels synthesized by sol-gel polycondensation of resorcinol with formaldehyde  

Microsoft Academic Search

Organic aerogels were synthesized via the sol-gel polycondensation of resorcinol with formaldehyde in a slightly basic aqueous solution and followed by supercritical drying with carbon dioxide. As a result of characterization by nitrogen adsorption, the resorcinol-formaldehyde (RF) aerogels were mesoporous materials with high surface areas and had few micropores. The surface area of the RF aerogel was controlled by the

H. Tamon; H. Ishizaka; M. Mikami; M. Okazaki

1997-01-01

337

Current Trends of Blanket Research and Development in Japan 5.The Frontiers of Research on Fusion Blanket Technology  

NASA Astrophysics Data System (ADS)

Current topics concerning blanket technology are reviewed. In the chemical engineering/chemistry area, the qualitative and quantitative effects of mass transfer steps of tritium is important in the understanding of the behavior of bred tritium in the solid breeder blanket system. Such phenomena as adsorption, isotope exchange reactions, and water formation reaction at the grain surface produce profound effects on the behavior of the bred tritium in the blanket. Regarding the liquid system, the physical or chemical properties of Li, Li17Pb83 and Flibe as liquid blanket materials were compared. Some recent studies were introduced regarding tritium recovery from the liquid blanket materials, impurity removal from salts, ceramic coating of structural materials, and the vapor pressure of mixtures of metals or salts. Thermal hydraulic topics in relation to several candidate power reactor concepts are summarized. Emphasis is laid on the simultaneous removal of heat and tritium from the blanket and some aspects of forming effective power cycles are developed.

Nishikawa, Masabumi; Fukada, Satoshi; Shimizu, Akihiko; Iguchi, Tetsuo

338

Bulk and surface light scattering from transparent silica aerogel  

NASA Astrophysics Data System (ADS)

Elastic light scattering has been used to study structural properties of different transparent aerogels, which may be used as filling materials in super-windows. With a goniometer having an angular resolution better than 0.6 degree(s) and a He-Ne laser as the light source we investigated the angular distribution of scattered intensity from transparent silica aerogels and one xerogel. The densities ranged between 0.11 and 0.60 gcm-3. An exponential correlation function for the density fluctuations of a random porous medium has been utilized to analyze the large-angle scattering, which is dominated by bulk scattering, for different polarization of the incident light. The determination of correlation lengths in the nanometer range was possible, because the absolute scattering intensities were determined. For relative angular dependence measurements, this range would have been accessible only to small angle x-ray scattering (SAXS). The resulting mean pore sizes between 8 nm and 50 nm and specific surface areas between 500 and 700 m2/g agree well with nitrogen-porosimetry data from the literature. The data compare quite well with correlation lengths calculated from specular transmittance data from an ordinary spectrophotometer. This method, which is not sensitive to the angular distribution of superposed forward scattering with large correlation lengths, has also been applied to a series of base-catalyzed TMOS aerogels with different catalyst concentrations. The forward scattering peak of the signal may be attributed to correlation lengths in the micrometer range. Experimental results for aerogel surfaces with evaporated aluminum indicate that this might be due to the surface properties. A quantitative analysis, however, is not possible yet.

Platzer, Werner J.; Bergkvist, Mikael

1992-11-01

339

Silica aerogel–iron oxide nanocomposites: structural and magnetic properties  

Microsoft Academic Search

Magnetic nanocomposites formed by iron oxide particles hosted in silica aerogels pores have been synthesized by sol–gel processes and supercritical evacuation of the solvent. Two iron-containing salts have been essayed: (A) Fe(NO3)·9H2O and (B) FeNa(EDTA)·2H2O. The synthetic routes made use of the gel pores as nanoreactors. Structural and magnetic properties have been studied by combining X-ray diffraction (XRD), N2 adsorption

L. Casas; A Roig; E Rodr??guez; E Molins; J Tejada; J Sort

2001-01-01

340

The Subcritical Preparation of Aerogels Based on Sodium Water Glass  

Microsoft Academic Search

A procedure is presented which involves working below the supercritical temperature and pressure and which conserves the structure of the wet gel. The fundamental step of the subcritical preparation of aerogels is the prevention of the condensation reaction of the =SisurfaceOH groups at the inner surface of the gel during drying. The reaction\\u000a$$2* \\\\equiv {\\\\text{Si}}_{{\\\\text{surface}}} {\\\\text{OH}} \\\\to \\\\equiv {\\\\text{Si}}

Thomas Gerber; Fachbereich Physik

1998-01-01

341

Current Status of Blanket Purchase Agreement Usage Within Marine Corps Field Contracting Activities.  

National Technical Information Service (NTIS)

This thesis examines the use of Blanket Purchase Agreements (BPA's) by Marine Corps field contracting activities. This research examines the regulations regarding the use of blanket purchase agreements and to what extent blanket purchase agreements are us...

W. Javoroski

1990-01-01

342

Systematic methodology for estimating direct capital costs for blanket tritium processing systems  

SciTech Connect

This paper describes the methodology developed for estimating the relative capital costs of blanket processing systems. The capital costs of the nine blanket concepts selected in the Blanket Comparison and Selection Study are presented and compared.

Finn, P.A.

1985-01-01

343

Carbon aerogel based electrode material for EAP actuators  

NASA Astrophysics Data System (ADS)

In this work we report an actuator material, that consist of carbon aerogel, 1-ethyl-3-methylimidazolium tetrafluoroborate (EMIBF4) and poly(vinylidene-co-hexafluoropropylene) (PVdF(HFP)). Actuators were made by using layer-by-layer casting method and they work as a bending actuators. Carbon aerogel is synthesized from 5- methylresorcinol, which is a waste product in oil-shale industry. It makes the material "environmentally green". Carbon aerogels have a very low density and considerable specific surface area. It is generally understood that the large interfacial surface area of electrodes gives rise to better actuation performance; therefore, designing actuators with high specific surface area electrodes is of interest. The assembled three layer actuators require low voltage to operate and work steadily in open air due to non-volatile electrolyte. The electromechanical and electrical characteristics of prepared actuators were examined and compared to our previously reported actuators based on the carbide-derived carbon and activated carbon electrodes. The differences in actuation performance were analyzed in the context of pore characteristics and degree of graphitization of carbons. The gas sorption measurements were performed to characterize pore size distribution. These actuators show high strain, low back-relaxation and low power consumption and they are good for slow-response applications compared to carbon nanotube actuators.

Kaasik, Friedrich; Torop, Janno; Peikolainen, Anna-Liisa; Koel, Mihkel; Aabloo, Alvo

2011-03-01

344

Effect of different trimethyl silylating agents on the hydrophobic and physical properties of silica aerogels  

Microsoft Academic Search

An essential feature of the ambient pressure dried aerogel manufacturing process is the end-capping of the reactive silanol groups in the silica wet gel. In this report, we have presented the effect of two different trimethyl silylating agents viz. trimethylchlorosilane (TMCS) and hexamethyldisilazane (HMDZ) on the hydrophobic and physical properties of ambient pressure dried silica aerogels. The hydrogels were prepared

Poonam M. Shewale; A. Venkateswara Rao; A. Parvathy Rao

2008-01-01

345

Equation of state and crushing dynamics of low-density silica aerogels.  

National Technical Information Service (NTIS)

Shock compression of low-density silica aerogels reveals a rate process associated with the crushing dynamics of the aerogel structure. Embedded magnetic impulse velocity gauge (MIV) experiments have been accomplished on density 0.3 and 0.12 g/cu cm mater...

R. Rabie J. J. Dick

1991-01-01

346

Making flexible magnetic aerogels and stiff magnetic nanopaper using cellulose nanofibrils as templates  

Microsoft Academic Search

Nanostructured biological materials inspire the creation of materials with tunable mechanical properties. Strong cellulose nanofibrils derived from bacteria or wood can form ductile or tough networks that are suitable as functional materials. Here, we show that freeze-dried bacterial cellulose nanofibril aerogels can be used as templates for making lightweight porous magnetic aerogels, which can be compacted into a stiff magnetic

R. T. Olsson; M. A. S. Azizi Samir; G. Salazar-Alvarez; L. Belova; V. Ström; L. A. Berglund; O. Ikkala; J. Nogués; U. W. Gedde

2010-01-01

347

Hydrophobic and low density silica aerogels dried at ambient pressure using TEOS precursor  

Microsoft Academic Search

In the conventional ambient pressure drying of silica aerogels, tedious repetitive gel washing and solvent exchange steps (?6 days) are involved. Therefore, in the present studies, we intended to reduce the processing time of TEOS based ambient pressure dried silica aerogels. Solvents such as methanol, hexane and Hexamethyldisilazane (HMDZ) as surface chemical modification agents have been used. To get good

Jyoti L. Gurav; A. Venkateswara Rao; Uzma K. H. Bangi

2009-01-01

348

Influence of Catalyst (Citric Acid) Concentration on the Physical Properties of TEOS Silica Aerogels  

Microsoft Academic Search

In the present paper, the experimental results on the influence of catalyst (citric acid) concentration on the physical properties of TEOS silica aerogels, are reported. The aerogels have been prepared by hydrolysis and polycondensation of tetraethoxysilane (TEOS) using citric acid (CTA) as a new catalyst followed by supercritical drying in an autoclave. In order to obtain the best quality silica

P. B. Wagh; A. Venkateswara Rao; D. Haranath

1997-01-01

349

Effect of solvents and catalysts on monolithicity and physical properties of silica aerogels  

Microsoft Academic Search

The effect of various solvents and catalysts on the monolithicity and physical properties of silica aerogels is reported. The aerogels were prepared by hydrolysis and polycondensation of tetramethoxysilane, followed by hypercritical drying, using 6 solvents of different chain lengths, and 17 catalysts consisting of strong and weak acids, bases and their mixtures. It was found that solvents of longer chain

A. Venkateswara Rao; G. M. Pajonk; N. N. Parvathy

1994-01-01

350

SAXS structural study of xerogels and aerogels formed from small-molecule organic gelators  

Microsoft Academic Search

Structure of monosaccharide gels formed from glucose-based gelators with organic solvents were studied using SAXS method, in wet state and after drying as xerogels and aerogels. Fractal analysis of the scattering data was carried out. It occurred that these gels essentially change their structure during drying. The structure of the xerogels indicates a strong collapse. The aerogels produced from the

H. Grigoriew; D. Chmielewska; J. Gronkowski

2008-01-01

351

Three-dimensional textural and compositional analysis of particle tracks and fragmentation history in aerogel  

SciTech Connect

We report analyses of aerogel tracks using (1) synchrotron X-ray computed microtomography (XRCMT), (2) laser confocal scanning microscopy (LCSM), and (3) synchrotron radiation X-ray fluorescence (SRXRF) of particles and their paths resulting from simulated hypervelocity impacts (1-2), and a single {approx}1 mm aerogel track from the Stardust cometary sample collector (1-3). Large aerogel pieces can be imaged sequentially, resulting in high spatial resolution images spanning many tomographic fields of view ('lambda-tomography'). We report calculations of energy deposited, and tests on aromatic hydrocarbons showing no alteration in tomography experiments. Imaging at resolutions from -17 to -1 micron/pixel edge (XRCMT) and to <100 nm/pixel edge (LCSM) illustrates track geometry and interaction of particles with aerogel, including rifling, particle fragmentation, and final particle location. We present a 3-D deconvolution method using an estimated point-spread function for aerogel, allowing basic corrections of LCSM data for axial distortion. LCSM allows rapid, comprehensive, non-destructive, high information return analysis of tracks in aerogel keystones, prior to destructive grain extraction. SRXRF with LCSM allows spatial correlation of grain size, chemical, and mineralogical data. If optical methods are precluded in future aerogel capture missions, XRCMT is a viable 3D imaging technique. Combinations of these methods allow for complete, nondestructive, quantitative 3-D analysis of captured materials at high spatial resolution. This data is fundamental to understanding the hypervelocity particle-aerogel interaction histories of Stardust grains.

Ebel, Denton S.; Greenberg, Michael; Rivers, Mark L.; Newville, Matthew; (AMNH)

2010-05-04

352

Three-dimensional textural and compositional analysis of particle tracks and fragmentation history in aerogel  

NASA Astrophysics Data System (ADS)

We report analyses of aerogel tracks using (1 synchrotron X-ray computed microtomography (XRCMT), (2) laser confocal scanning microscopy (LCSM), and (3) synchrotron radiation X-ray fluorescence (SRXRF) of particles and their paths resulting from simulated hypervelocity impacts (1-2), and a single ~1 mm aerogel track from the Stardust cometary sample collector (1-3). Large aerogel pieces can be imaged sequentially, resulting in high spatial resolution images spanning many tomographic fields of view (‘lambda-tomography’). We report calculations of energy deposited, and tests on aromatic hydrocarbons showing no alteration in tomography experiments. Imaging at resolutions from ~17 to ~1 micron/pixel edge (XRCMT) and to <100 nm/ pixel edge (LCSM) illustrates track geometry and interaction of particles with aerogel, including rifling, particle fragmentation, and final particle location. We present a 3-D deconvolution method using an estimated point-spread function for aerogel, allowing basic corrections of LCSM data for axial distortion. LCSM allows rapid, comprehensive, non-destructive, high information return analysis of tracks in aerogel keystones, prior to destructive grain extraction. SRXRF with LCSM allows spatial correlation of grain size, chemical, and mineralogical data. If optical methods are precluded in future aerogel capture missions, XRCMT is a viable 3D imaging technique. Combinations of these methods allow for complete, nondestructive, quantitative 3-D analysis of captured materials at high spatial resolution. This data is fundamental to understanding the hypervelocity particle-aerogel interaction histories of Stardust grains.

Ebel, D. S.; Greenberg, M.; Rivers, M. L.; Newville, M.

2009-11-01

353

Method for Bonding Insulator to Insulator.  

National Technical Information Service (NTIS)

A method for making an airtight seal between a pair of insulator elements, such as glass plates, without destroying any fine structure etched in the insulator elements. A thin metal film is deposited on one of the elements to be sealed and then placed in ...

H. Wohltjen J. F. Giuliani

1982-01-01

354

Disordered Floquet topological insulators  

NASA Astrophysics Data System (ADS)

In the presence of an external periodic field some materials become Floquet topological insulators. Introducing disorder into these systems may alter their electronic properties, which may critically affect their applications. We investigate the effects of disorder on Floquet topological insulators using a Green's function formalism. We find that in the presence of disorder, the transport properties of Floquet topological insulators differ from those of standard topological insulators. We further investigate the robustness of the topological phase to disorder.

Baruch, Shirit; Pereg-Barnea, Tami

2013-03-01

355

Carbon Quantum Dot-Functionalized Aerogels for NO2 Gas Sensing.  

PubMed

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%. The prepared porous CQD-aerogel hybrid material could maintain its excellent fluorescence (FL) activity in its solid state. The FL of CQD-aerogel hybrid material could be selectively and sensitively quenched by NO2 gas, suggesting a promising application of the new FL-functionalized aerogels in gas sensing. PMID:23905622

Wang, Ruixue; Li, Geli; Dong, Yongqiang; Chi, Yuwu; Chen, Guonan

2013-08-14

356

Density Uniform and Surface Characterization of Tantalum Oxide Aerogel for Radiation Transport Experiments  

NASA Astrophysics Data System (ADS)

Tantalum aerogel was fabricated and machined at General Atomics for radiation transport experiments at the OMEGA laser facility. These targets are machined into small disks from 250 or 500 mg/cc tantalum oxide aerogel. During machining, differences in density uniformity and machining characteristics were observed in some of the aerogels. Ultimately, rough surfaces or intrinsic density variations in the sample can lead to areal density non-uniformities that can affect the experiment. Using contact radiography, optical profilometry, and scanning electron microscopy the surface roughness and areal density uniformity were quantified. This information was used to improve the synthesis procedure of the bulk aerogel material to fabricate more uniform aerogel targets and provide input for comparison shot data of experiment vs modeling data.

Hund, J. F.; Frederick, C. A.; Tipton, A. P.; Giraldez, E. M.; Kaae, J. L.; Back, C. A.; Hoppe, M. L., Jr.

2007-11-01

357

Adsorption of toxic organic compounds from water with hydrophobic silica aerogels.  

PubMed

Silica monolith aerogels with different degrees of hydrophobicity were prepared by incorporating methyltrimethoxysilane (MTMS) or trimethylethoxysilane (TMES) in standard sol-gel synthesis followed by supercritical drying of gels with carbon dioxide (CO(2)) at 40 degrees C and 100 bar. The hydrophobicity of the aerogels was tested by measuring the contact angle (theta). The aerogels were also characterised by FTIR, DSC, and porosity measurements. Adsorption capacity measurements show that such modified hydrophobic silica aerogels are excellent adsorbents for different toxic organic compounds from water. In comparison to granulated active carbon (GAC) they exhibit capacities which are from 15 to 400 times higher for all tested compounds. Adsorption properties of hydrophobic silica aerogel remain stable even after 20 adsorption/desorption cycles. PMID:17350031

Standeker, Suzana; Novak, Zoran; Knez, Zeljko

2007-02-14

358

Organic modification of TEOS based silica aerogels using hexadecyltrimethoxysilane as a hydrophobic reagent  

NASA Astrophysics Data System (ADS)

The experimental results on the synthesis and characterization of tetraethoxysilane (TEOS) based hydrophobic silica aerogels using hexadecyltrimethoxysilane (HDTMS) as a hydrophobic reagent by two step sol-gel process, are described. The molar ratio of tetraethoxysilane (TEOS), methanol (MeOH), acidic water (0.001 M, oxalic acid) and basic water (10 M, NH 4OH) was kept constant at 1:55:3.25:1.25 and the molar ratio of HDTMS/TEOS (M) was varied from 0 to 28.5 × 10 -2. The organic modification was confirmed by infrared spectroscopic studies, and the hydrophobicity of the aerogels was tested by the contact angle measurements. The maximum contact angle of 152° was obtained for M = 22.8 × 10 -2. The aerogels retained the hydrophobicity up to a temperature of 240 °C and above this temperature the aerogels became hydrophilic. The aerogels were characterized by the thermal conductivity, density, contact angle measurements, optical transmission and scanning electron micrographs.

Hegde, Nagaraja D.; Venkateswara Rao, A.

2006-11-01

359

Insulated waterproof drainage material  

Microsoft Academic Search

An insulative waterproof drainage material is described comprising: a sheet of rigid material having hills and valleys therein to define a core having opposed surfaces; permeable fabric material attached to one of the opposed surfaces; and a layer of thermally insulative material on the other of the opposed surfaces. The insulative material has first surface covering the hills and valleys

Tarko

1988-01-01

360

Vacuum insulator coating development  

Microsoft Academic Search

The authors discuss the electrical and mechanical requirements for vacuum insulators in high peak power generators. To increase the lifetime of these insulators, they have developed a coating called Dendresist. This coating has extended the insulator lifetime on the PITHON, DM2, CASINO, and Double-EAGLE pulsed power generators. They describe its development, and compare its electrical and mechanical strength to that

I. S. Roth; P. S. Sincerny; L. Mandelcorn; M. Mendelsohn; D. Smith; T. G. Engel; L. Schlitt; C. M. Cooke

1997-01-01

361

ITER solid breeder blanket materials database  

SciTech Connect

The databases for solid breeder ceramics (Li{sub 2},O, Li{sub 4}SiO{sub 4}, Li{sub 2}ZrO{sub 3} and LiAlO{sub 2}) and beryllium multiplier material are critically reviewed and evaluated. Emphasis is placed on physical, thermal, mechanical, chemical stability/compatibility, tritium, and radiation stability properties which are needed to assess the performance of these materials in a fusion reactor environment. Correlations are selected for design analysis and compared to the database. Areas for future research and development in blanket materials technology are highlighted and prioritized.

Billone, M.C. [Argonne National Lab., IL (United States); Dienst, W. [Kernforschungszentrum Karlsruhe GmbH (Germany). Inst. fuer Material- und Festkoerperforschung; Flament, T. [CEA Centre d`Etudes de Fontenay-aux-Roses (France). Commissariat A L`Energie Atomique; Lorenzetto, P. [NET Team, Garching (Germany); Noda, K. [Japan Atomic Energy Research Inst., Takai, Ibaraki, (Japan); Roux, N. [CEA Centre d`Etudes et de Recherches Les Materiaux (France). Commissariat a L`Energie Atomique

1993-11-01

362

Thermal control of solid breeder blankets  

SciTech Connect

An assessment of the thermal control mechanisms applicable to solid breeder blanket designs under ITER-like operating conditions is presented in this paper. Four cases are considered: a helium gap; a sintered block Be region; a sintered block helium region with a metallic felt at the Be/clad interface; and a Be packed bed region. For these cases, typical operating are explored to determine the ranges of wall load which can be accommodated while maintaining the breeder within its allowable operating temperature window. The corresponding region thicknesses are calculated to help identify practicality and design tolerances.

Raffray, A.R.; Ying, A.; Gorbis, Z.; Tillack, M.S.; Abdou, M.A.

1991-01-01

363

Thermal control of solid breeder blankets  

SciTech Connect

An assessment of the thermal control mechanisms applicable to solid breeder blanket designs under ITER-like operating conditions is presented in this paper. Four cases are considered: a helium gap; a sintered block Be region; a sintered block helium region with a metallic felt at the Be/clad interface; and a Be packed bed region. For these cases, typical operating are explored to determine the ranges of wall load which can be accommodated while maintaining the breeder within its allowable operating temperature window. The corresponding region thicknesses are calculated to help identify practicality and design tolerances.

Raffray, A.R.; Ying, A.; Gorbis, Z.; Tillack, M.S.; Abdou, M.A.

1991-12-31

364

Dependence of multi-layer insulation thermal performance on interstitial gas pressure  

NASA Astrophysics Data System (ADS)

Four examples of multi-layer insulation (MLI) blankets, differing in layer density, thickness, and spacer type, were evaluated using the Cryostat-100 fixture, a cylindrical calorimeter, in the Cryogenic Test Laboratory at Kennedy Space Center. The steady state thermal performance of each was measured at pressures ranging from high vacuum (down to 10-6 Torr) up to 1 atmosphere. The four heat flux versus pressure data sets were reduced to a single "universal curve", demonstrating the essential parameters that determine how the performance of a generic blanket depends on interstitial gas pressure. A simple phenomenological model based on molecular collision probabilities is followed by a systematic curve fitting procedure encompassing the entire pressure range. The final result is a closed-form expression for the pressure-dependent heat flux that can be readily generalized to arbitrary thermal boundary temperatures, gas species, and MLI blanket thickness and layer density.

Feller, Jeffrey Robert; Johnson, Wesley

2012-06-01

365

Security Blankets and Children's Security of Attachment to Their Mothers.  

ERIC Educational Resources Information Center

|This study investigated the relations between toddlers' degree of attachment to their mothers and their development of an attachment to a security blanket. Seventy-four 18-month-olds were separated from their mothers three times; the third time the toddlers were left for 5 minutes in an unfamiliar playroom with their blanket and with a stranger.…

Donate-Bartfield, Evelyn L.; Passman, Richard H.

366

An assessment of the base blanket for ITER  

SciTech Connect

Ideally, the ITER base blanket would provide the necessary tritium for the reactor to be self-sufficient during operation, while having minimal impact on the overall reactor cost, reliability and safety. A solid breeder blanket has been developed in CDA phase in an attempt to achieve such objectives. The reference solid breeder base blanket configurations at the end of the CDA phase has many attractive features such as a tritium breeding ratio (TBR) of 0.8--0.9 and a reasonably low tritium inventory. However, some concerns regarding the risk, cost and benefit of the base blanket have been raised. These include uncertainties associated with the solid breeder thermal control and the potentially high cost of the amount of Be used to achieve high TBR and to provide the necessary thermal barrier between the high temperature solid breeder and low temperature coolant. This work addresses these concerns. The basis for the selection of a breeding blanket is first discussed in light of the incremental risk, cost and benefits relative to a non-breeding blanket. Key issues associated with the CDA breeding blanket configurations are then analyzed. Finally, alternative schemes that could enhance the attractiveness and flexibility of a breeding blanket are explored.

Raffray, A.R.; Abdou, M.A.; Ying, A.

1991-12-31

367

An assessment of the base blanket for ITER  

SciTech Connect

Ideally, the ITER base blanket would provide the necessary tritium for the reactor to be self-sufficient during operation, while having minimal impact on the overall reactor cost, reliability and safety. A solid breeder blanket has been developed in CDA phase in an attempt to achieve such objectives. The reference solid breeder base blanket configurations at the end of the CDA phase has many attractive features such as a tritium breeding ratio (TBR) of 0.8--0.9 and a reasonably low tritium inventory. However, some concerns regarding the risk, cost and benefit of the base blanket have been raised. These include uncertainties associated with the solid breeder thermal control and the potentially high cost of the amount of Be used to achieve high TBR and to provide the necessary thermal barrier between the high temperature solid breeder and low temperature coolant. This work addresses these concerns. The basis for the selection of a breeding blanket is first discussed in light of the incremental risk, cost and benefits relative to a non-breeding blanket. Key issues associated with the CDA breeding blanket configurations are then analyzed. Finally, alternative schemes that could enhance the attractiveness and flexibility of a breeding blanket are explored.

Raffray, A.R.; Abdou, M.A.; Ying, A.

1991-01-01

368

Leachate Recirculation Using Permeable Blankets in Engineered Landfills  

Microsoft Academic Search

Subsurface leachate recirculation or liquid injection methods for municipal solid waste MSW landfills are horizontal trenches, vertical wells, and permeable blankets. In this study, results of field-scale testing and numerical modeling of a recently developed subsurface leachate recirculation system called permeable blankets have been presented. In the field, at a MSW landfill located in Michigan, the travel of injected leachate

Mazen M. Haydar; Milind V. Khire

2007-01-01

369

US blanket technology programs. [Directory of current research  

SciTech Connect

Experimental research in US programs related to blanket technology is described through brief summaries of the objectives, facilities, recent experimental results and principal investigators for the Blanket Technology Program, TRIO-1 Experiment, TSTA, Fusion Hybrid Program and selected activities in the Fusion Materials and Fusion Safety Programs in neutronics research.

Nygren, R.E.

1985-01-01

370

NEUTRONICS DESIGN STUDIES OF AN LBE COOLED ATW BLANKET  

Microsoft Academic Search

As part of the Advanced Accelerator Application (AAA) program in the US, preliminary trade studies have been performed at Argonne National Laboratory (ANL) and Los Alamos National Laboratory (LANL) to define and compare candidate Accelerator Transmutation of Waste (ATW) systems. The studies at ANL have focused primarily on the blanket component of the overall system, because the choice of blanket

W. S. YANG; H. S. KHALIL

371

Tritium management in HCLL-PPCS model AB blanket  

Microsoft Academic Search

When dealing with activities related to the design and optimisation of the Helium Cooled Lithium Lead (HCLL) blanket, doubts arose in the past about the technical feasibility of the tritium processing system. The questionable feasibility was due to the heavy performance requirements for different tritium processing subsystems, mainly consequence of the high tritium permeation rate from the breeding blanket into

I. Ricapito; A. Aiello; A. Ciampichetti; G. Benamati; M. Utili; M. Zucchetti

2007-01-01

372

High power density self-cooled lithium-vanadium blanket.  

National Technical Information Service (NTIS)

A self-cooled lithium-vanadium blanket concept capable of operating with 2 MW/m(sup 2) surface heat flux and 10 MW/m(sup 2) neutron wall loading has been developed. The blanket has liquid lithium as the tritium breeder and the coolant to alleviate issues ...

Y. Gohar S. Majumdar D. Smith

1999-01-01

373

Conceptual design of a self-cooled FLIBE blanket  

Microsoft Academic Search

A self-cooled Flibe blanket concept is developed. The problems associated with tritium breeding, tritium containment, and corrosion are investigated and potential solutions developed. A highly efficient and compact blanket and power conversion system is incorporated. The resulting system is low pressure with high thermal efficiency and is inherently safe.

D. K. Sze; J. Jung; E. T. Cheng; S. Piet; A. Klein

1986-01-01

374

Conceptual design of a self-cooled FLIBE blanket  

SciTech Connect

A self-cooled Flibe blanket concept is developed. The problems associated with tritium breeding, tritium containment, and corrosion are investigated and potential solutions developed. A highly efficient and compact blanket and power conversion system is incorporated. The resulting system is low pressure with high thermal efficiency and is inherently safe.

Sze, D.K.; Jung, J.; Cheng, E.T.; Piet, S.; Klein, A.

1986-11-01

375

Conceptual design of a self-cooled Flibe blanket  

SciTech Connect

A self-cooled Flibe blanket concept has been developed. The problems associated with tritium breeding, tritium containment, and corrosion have been investigated and potential solutions developed. A highly efficient and compact blanket and power conversion system has been incorporated. The resulting system is low pressure with high thermal efficiency and is inherently safe.

Sze, D.K.; Jung, J.; Cheng, E.T.; Piet, S.; Klein, A.

1986-06-01

376

Conceptual design of a self-cooled Flibe blanket  

Microsoft Academic Search

A self-cooled Flibe blanket concept has been developed. The problems associated with tritium breeding, tritium containment, and corrosion have been investigated and potential solutions developed. A highly efficient and compact blanket and power conversion system has been incorporated. The resulting system is low pressure with high thermal efficiency and is inherently safe.

D. K. Sze; J. Jung; E. T. Cheng; S. Piet; A. Klein

1986-01-01

377

Helium-cooled, flibe breeder, beryllium multiplier blanket  

Microsoft Academic Search

The concept described for the blanket surrounding a fusion reaction chamber is based on the use of molten fluoride salts to convert fusion energy into electricity and to breed the tritium fuel for the fusion power plant. Helium cools the first-wall and the blanket internals, which consist of a bed of beryllium balls in which neutrons are multiplied. The neutrons

R. W. Moir; D. H. Berwald; J. H. De Van; J. Jung; J. D. Lee; R. C. Muninger; W. S. Neef; A. E. Sherwood

1985-01-01

378

Neutronics Investigation into Lithium/Vanadium Test Blanket Modules  

SciTech Connect

A neutronics-based investigation was carried out for self-cooled Blanket Test Modules in ITER with coolant of liquid lithium and structural materials of V-4Cr-4Ti. The design feasibility was demonstrated for the test module having the purpose to validate the tritium self sufficiency for DEMO Li/V blanket without neutron multiplier Be.

Muroga, T.; Tanaka, T. [Fusion Engineering Research Center, National Institute for Fusion Science (United States)

2005-04-15

379

Biocompatibility of surfactant-templated polyurea-nanoencapsulated macroporous silica aerogels with plasma platelets and endothelial cells.  

PubMed

The recently synthesized polyurea-nanoencapsulated surfactant-templated aerogels (X-aerogels) are porous materials with significantly improved mechanical strengths. Surface-wise they resemble polyurethane, a common biocompatible material, but their biocompatibility has never been investigated. As lightweight and strong materials, if X-aerogels also have acceptable biocompatibility, they may be used in many implantable devices. The goal of this study was to investigate their biocompatibility toward platelets, blood plasma, and vascular endothelial cells, in terms of cell activation and inflammatory responses. Platelets were incubated with X-aerogel and platelet activation was measured through CD62P and phosphatidylserine expression. Platelet aggregation was also measured. Contact with X-aerogel did not induce platelet activation or impair aggregation. To determine X-aerogel-induced inflammation, plasma anaphylatoxin C3a level was measured after incubation with X-aerogel. Results showed that X-aerogel induced no changes in plasma C3a levels. SEM and SDS-PAGE were used to examine cellular/protein deposition on X-aerogel samples after plasma incubation. No structural change or organic deposition was detected. Furthermore, X-aerogel samples did not induce any significant changes in vascular endothelial cell culture parameters after 5 days of incubation. These observations suggest that X-aerogels have a suitable biocompatibility toward platelets, plasma, and vascular endothelial cells, and they have potential for use in blood implantable devices. PMID:19358258

Yin, Wei; Venkitachalam, Subramaniam M; Jarrett, Ellen; Staggs, Sarah; Leventis, Nicholas; Lu, Hongbing; Rubenstein, David A

2010-03-15

380

MHD Effects on Heat Transfer in a Molten Salt Blanket  

SciTech Connect

Heat transfer in closed channel flows of molten salts (MS)s, such as FLiBe or FLiNaBe, has been considered under specific reactor conditions. MHD effects have been accessed for two blanket concepts: self-cooled MS blanket, and dual-coolant MS blanket. The effect of heat transfer degradation due to turbulence reduction by a magnetic field in the First Wall channels of the self-cooled blanket was analyzed with the K-{epsilon} model of turbulence. In the dual-coolant blanket, the MS flow is laminar. A 2-D MHD code was used to calculate the laminar velocity profile first. Then, the temperature field was calculated using a 3-D temperature code. Reasonable interface temperatures below the material limit of 550 deg. C, and low heat escape from the breeder zone have been demonstrated. Model limitations and the ways of their improvement are also discussed.

Smolentsev, Sergey; Miraghaie, Reza; Abdou, Mohamed [University of California (United States)

2005-04-15

381

Thermal performance of a liquid hydrogen tank multilayer insulation system at warm boundary temperatures of 630, 530, and 152 R  

NASA Astrophysics Data System (ADS)

The results are presented of a study conducted to obtain experimental heat transfer data on a liquid hydrogen tank insulated with 34 layers of MLI (multilayer insulation) for warm side boundary temperatures of 630, 530, and 150 R. The MLI system consisted of two blankets, each blanket made up of alternate layers of double silk net (16 layers) and double aluminized Mylar radiation shields (15 layers) contained between two cover sheets of Dacron scrim reinforced Mylar. The insulation system was designed for and installed on a 87.6 in diameter liquid hydrogen tank. Nominal layer density of the insulation blankets is 45 layers/in. The insulation system contained penetrations for structural support, plumbing, and electrical wiring that would be representative of a cryogenic spacecraft. The total steady state heat transfer rates into the test tank for shroud temperatures of 630, 530, 152 R were 164.4, 95.8, and 15.9 BTU/hr respectively. The noninsulation heat leaks into the tank (12 fiberglass support struts, tank plumbing, and instrumentation lines) represent between 13 to 17 pct. of the total heat input. The heat input values would translate to liquid H2 losses of 2.3, 1.3, and 0.2 pct/day, with the tank held at atmospheric pressure.

Stochl, Robert J.; Knoll, Richard H.

1991-06-01

382

Thermal performance of a liquid hydrogen tank multilayer insulation system at warm boundary temperatures of 630, 530, and 152 R  

NASA Astrophysics Data System (ADS)

The results are presented of a study conducted to obtain experimental heat transfer data on a liquid hydrogen tank insulated with 34 layers of MLI (multilayer insulation) for warm side boundary temperatures of 630, 530, and 150 R. The MLI system consisted of two blankets, each blanket made up of alternate layers of double silk net (16 layers) and double aluminized Mylar radiation shields (15 layers) contained between two cover sheets of Dacron scrim reinforced Mylar. The insulation system was designed for and installed on an 87.6 in. diameter liquid hydrogen tank. Nominal layer density of the insulation blankets is 45 layers/in. The insulation system contained penetrations for structural support, plumbing, and electrical wiring that would be representative of a cryogenic spacecraft. The total steady state heat transfer rates into the test tank for shroud temperatures of 630, 530, 152 R were 164.4, 95.8, and 15.9 BTU/hr, respectively. The noninsulation heat leaks into the tank (12 fiberglass support struts, tank plumbing, and instrumentation lines) represent between 13 to 17 pct. of the total heat input. The heat input values would translate to liquid H2 losses of 2.3, 1.3, and 0.2 pct/day, with the tank held at atmospheric pressure.

Stochl, Robert J.; Knoll, Richard H.

1991-06-01

383

Updating pipe insulation  

SciTech Connect

Every plant engineer knows that proper insulation saves energy. The right insulation also increases plant yields and capacity without capital expansion. Field experience has shown that proper insulation, a combination of the right material, thickness, and jacketing helps maintain optimum temperatures throughout a process. The result is processes that safely run hotter and faster, and produce more acceptable product. In hydrocarbon processing, for example, insulating fuel, lubricant, and petrochemical lines helps ensure more premium-grade product. In power generation, better insulation means more saleable electricity per ton of fuel. In chemical processing, properly insulating process heat lines for reactor vessels and turbines means consistent product and less scrap. The same holds true for pulp and paper processing (especially at the pulping end), textile manufacturing, and food processing. This paper briefly explains a 5-step program to help a plant engineer determine the plant's pipe insulation requirements.

Rickards, D. (CertainTeed Corp., Valley Forge, PA (United States))

1993-03-04

384

Physical and mechanical characteristics and chemical compatibility of aluminum nitride insulator coatings for fusion reactor applications  

SciTech Connect

The blanket system is one of the most important components in a fusion reactor because it has a major impact on both the economics and safety of fusion energy. The primary functions of the blanket in a deuterium/tritium-fueled fusion reactor are to convert the fusion energy into sensible heat and to breed tritium for the fuel cycle. The Blanket Comparison and Selection Study, conducted earlier, described the overall comparative performance of various concepts, including liquid metal, molten salt, water, and helium. Based on the requirements for an electrically insulating coating on the first-wall structural material to minimize the MHD pressure drop during the flow of liquid metal in a magnetic field, AlN was selected as a candidate coating material for the Li self-cooled blanket concept. This report discusses the results from an ongoing study of physical and mechanical characteristics and chemical compatibility of AlN electrical insulator coatings in a liquid Li environment. Details are presented on the AlN coating fabrication methods, and experimental data are reported for microstructures, chemistry of coatings, pretreatment of substrate, heat treatment of coatings, hardness data for coatings, coating/lithium interactions, and electrical resistance before and after exposure to lithium. Thermodynamic calculations are presented to establish regions of stability for AlN coatings in an Li environment as a function of O concentration and temperature, which can aid in-situ development of AlN coatings in Li.

Natesan, K.; Rink, D.L. [Argonne National Lab., IL (United States). Energy Technology Div.

1996-04-01

385

The Breeding Blanket Interface (BBI): Recent results for the solid breeder and the aqueous salt solution blanket concepts  

SciTech Connect

The Tritium Systems Test Assembly (TSTA) at Los Alamos is a full-scale facility dedicated to testing tritium processing for fusion reactors. We are involved in a study of adding a Breeder Blanket Interface (BBI) to the TSTA. The BBI is to test the processing required for the tritium output streams for the various fusion reactor breeder blankets. In the current phase of the study, we are evaluating the characteristics of the output from various breeding blankets types. Emphasis is placed on defining the output stream with respect to H/T ratio, impurity content, and radionuclide content. Reported herein is an assessment for two blanket concepts: solid breeder blanket (ceramic, Li{sub 2}O), and aqueous salt solution. 24 refs., 2 figs., 2 tabs.

Clemmer, R.G.; Finn, P.A.; Greenwood, L.R.; Sze, D.K.; Bartlit, J.R.; Sherman, R.; Anderson, J.L.; Yoshida, H.; Naruse, Y.; Enoeda, M.; Okuno, K. (Argonne National Lab., IL (USA); Los Alamos National Lab., NM (USA); Japan Atomic Energy Research Inst., Tokai, Ibaraki (Japan))

1989-10-01

386

Structural characterization of hierarchically porous alumina aerogel and xerogel monoliths.  

PubMed

Detailed nanostructures have been investigated for hierarchically porous alumina aerogels and xerogels prepared from ionic precursors via sol-gel reaction. Starting from AlCl3.-6H2O and poly(ethylene oxide) (PEO) dissolved in a H2O/EtOH mixed solvent, monolithic wet gels were synthesized using propylene oxide (PO) as a gelation initiator. Hierarchically porous alumina xerogels and aerogels were obtained after evaporative drying and supercritical drying, respectively. Macroporous structures are formed as a result of phase separation, while interstices between the secondary particles in the micrometer-sized gel skeletons work as mesoporous structures. Alumina xerogels exhibit considerable shrinkage during the evaporative drying process, resulting in relatively small mesopores (from 5.4 to 6.2 nm) regardless of the starting composition. For shrinkage-free alumina aerogels, on the other hand, the median mesopore size changes from 13.9 to 33.1 nm depending on the starting composition; the increases in PEO content and H2O/EtOH volume ratio both contribute to producing smaller mesopores. Small-angle X-ray scattering (SAXS) analysis reveals that variation of median mesopore size can be ascribed to the change in agglomeration state of primary particles. As PEO content and H2O/EtOH ratio increase, secondary particles become small, which results in relatively small mesopores. The results indicate that the agglomeration state of alumina primary particles is influenced by the presence of weakly interacting phase separation inducers such as PEO. PMID:19646712

Tokudome, Yasuaki; Nakanishi, Kazuki; Kanamori, Kazuyoshi; Fujita, Koji; Akamatsu, Hirofumi; Hanada, Teiichi

2009-06-21

387

Inorganic hollow nanotube aerogels by atomic layer deposition onto native nanocellulose templates.  

PubMed

Hollow nano-objects have raised interest in applications such as sensing, encapsulation, and drug-release. Here we report on a new class of porous materials, namely inorganic nanotube aerogels that, unlike other aerogels, have a framework consisting of inorganic hollow nanotubes. First we show a preparation method for titanium dioxide, zinc oxide, and aluminum oxide nanotube aerogels based on atomic layer deposition (ALD) on biological nanofibrillar aerogel templates, that is, nanofibrillated cellulose (NFC), also called microfibrillated cellulose (MFC) or nanocellulose. The aerogel templates are prepared from nanocellulose hydrogels either by freeze-drying in liquid nitrogen or liquid propane or by supercritical drying, and they consist of a highly porous percolating network of cellulose nanofibrils. They can be prepared as films on substrates or as freestanding objects. We show that, in contrast to freeze-drying, supercritical drying produces nanocellulose aerogels without major interfibrillar aggregation even in thick films. Uniform oxide layers are readily deposited by ALD onto the fibrils leading to organic-inorganic core-shell nanofibers. We further demonstrate that calcination at 450 °C removes the organic core leading to purely inorganic self-supporting aerogels consisting of hollow nanotubular networks. They can also be dispersed by grinding, for example, in ethanol to create a slurry of inorganic hollow nanotubes, which in turn can be deposited to form a porous film. Finally we demonstrate the use of a titanium dioxide nanotube network as a resistive humidity sensor with a fast response. PMID:21361349

Korhonen, Juuso T; Hiekkataipale, Panu; Malm, Jari; Karppinen, Maarit; Ikkala, Olli; Ras, Robin H A

2011-03-01

388

Effects of nanoparticle shape on the morphology and properties of porous CdSe assemblies (aerogels).  

PubMed

We demonstrate the effect of differently shaped CdSe nanoscale building blocks (dots, rods, branched nanoparticles, and hyperbranched nanoparticles) on the morphologies, surface characteristics, and optical properties of resultant porous CdSe nanostructured aerogels. Monolithic CdSe aerogels were produced by controlled oxidative removal of surface thiolate ligands from differently shaped CdSe nanoparticles to yield a wet gel, followed by CO(2) supercritical drying. The X-ray diffraction data show that the resultant CdSe aerogels maintain the crystalline phase of the building blocks without significant grain growth. However, the transmission electron microscopy images indicate that the morphology of CdSe aerogels changes from a colloid-type morphology to a polymer-type morphology when the building block changes from dot to rod or the branched nanoparticle. The morphology of the CdSe aerogel assembled from hyperbranched nanoparticles appears to be intermediate between the colloid-type and the polymer-type. Nitrogen physisorption measurements suggest that the surface areas and porosity are a direct function of the shape of the primary building blocks, with aerogels formed from rods or branched particles exhibiting the greatest surface areas (>200 m(2)/g) and those prepared from hyperbranched nanoparticles exhibiting the least (<100 m(2)/g). Band gap measurements and photoluminescence studies show that the as-prepared CdSe aerogels retain to a large extent the intrinsic quantum confinement of the differently shaped building blocks, despite being connected into a 3D network. PMID:19206358

Yu, Hongtao; Brock, Stephanie L

2008-08-01

389

Neutronic assessment of He-cooled molten Li fusion blanket  

SciTech Connect

This study is intended to assess overall neutronic performances of He-cooled molten Li (HCML) blanket with a reflector and investigate the impact of {sup 6}Li enrichment on tritium breeding ratio (TBR). To precisely evaluate the neutronic performances of the reflected HCML blanket, three-dimensional D-shape torus model is utilized and Monte-Carlo calculations are performed. In this study, the neutronic characteristics of five potential reflector candidates are compared and the reflected blanket is also optimized from the neutronic point of view. Taking into account the material availability and potential safety features, a high-density graphite reflector can be a practical choice for a high-performance HCML blanket. The graphite-reflected HCML blanket shows the best performances when the reflector is placed such that the blanket is divided into a thick front region and a thin back region. The HCML blanket with a slightly-enriched Li (8-10 wt% {sup 6}Li) breeder shows the highest TBR. (authors)

Han, B. [Nuclear Engineering Dept., Seoul National Univ., San 56-1, Shinlim-dong, Kwanak-gu, Seoul (Korea, Republic of); Kim, Y. [Korea Atomic Energy Research Inst., 150, Deokjin-dong, Yuseong-gu, Daejeon (Korea, Republic of); Kim, C. H. [Nuclear Engineering Dept., Seoul National Univ., San 56-1, Shinlim-dong, Kwanak-gu, Seoul (Korea, Republic of)

2006-07-01

390

EU Blanket Design Activities and Neutronics Support Efforts  

SciTech Connect

An overview is provided of the design activities and the related neutronics support efforts conducted in the European Union for the development of breeder blankets for future fusion power reactors. The EU fusion programme considers two blanket lines, the Helium-Cooled Pebble Bed (HCPB) blanket with Lithium ceramics pebbles (Li{sub 4}SiO{sub 4} or Li{sub 2}TiO{sub 3}) as breeder and beryllium pebbles as neutron multiplier, and the Helium-Cooled Lithium-Lead (HCLL) blanket with the Pb-Li eutectic alloy as breeder and neutron multiplier. The blanket design and the related R and D efforts are based on the use of the same coolant and the same modular blanket structure to minimise the development costs as much as possible. The neutronic support efforts include design analyses for the layout and optimization of the modular HCPB/HCLL blankets based on detailed three-dimensional Monte Carlo calculations as well as underlying neutronics activities conducted in the frame of the European Fusion and Activation File (EFF/EAF) projects to develop qualified nuclear data and computational tools for reliable neutronics design calculations.

Fischer, U. [Forschungszentrum Karlsruhe (Germany); Batistoni, P. [ENEA Fusion Division (Italy); Boccaccini, L.V. [Forschungszentrum Karlsruhe (Germany); Giancarli, L. [CEA Saclay (France); Hermsmeyer, S. [Forschungszentrum Karlsruhe (Germany); Poitevin, Y. [CEA Saclay (France)

2005-05-15

391

Simplified procedure for encapsulating cytochrome c in silica aerogel nanoarchitectures while retaining gas-phase bioactivity.  

PubMed

Cytochrome c (cyt. c) has been encapsulated in silica sol-gels and processed to form bioaerogels with gas-phase activity for nitric oxide through a simplified synthetic procedure. Previous reports demonstrated a need to adsorb cyt. c to metal nanoparticles prior to silica sol-gel encapsulation and processing to form aerogels. We report that cyt. c can be encapsulated in aerogels without added nanoparticles and retain structural stability and gas-phase activity for nitric oxide. While the UV-visible Soret absorbance and nitric oxide response indicate that cyt. c encapsulated with nanoparticles in aerogels remains slightly more stable and functional than cyt. c encapsulated alone, these properties are not very different in the two types of aerogels. From UV-visible and Soret circular dichroism results, we infer that cyt. c encapsulated alone self-organizes to reduce contact with the silica gel in a way that may bear at least some resemblance to the way cyt. c self-organizes into superstructures of protein within aerogels when nanoparticles are present. Both the buffer concentration and the cyt. c concentration of solutions used to synthesize the bioaerogels affect the structural integrity of the protein encapsulated alone within the dried aerogels. Optimized bioaerogels are formed when cyt. c is encapsulated from 40 mM phosphate buffered solutions, and when the loaded cyt. c concentration in the aerogel is in the range of 5 to 15 ?M. Increased viability of cyt. c in aerogels is also observed when supercritical fluid used to produce aerogels is vented over relatively long times. PMID:22924640

Harper-Leatherman, Amanda S; Iftikhar, Mariam; Ndoi, Adela; Scappaticci, Steven J; Lisi, George P; Buzard, Kaitlyn L; Garvey, Elizabeth M

2012-10-04

392

Precipitation behavior in F82H during heat treatments of blanket fabrication  

Microsoft Academic Search

Reduced Activation Ferritic\\/Martensitic steels are leading candidates for the structural material of DEMO blanket module, and they are really used for the ITER test blanket module. During the fabrication process of blanket module, the structural material is exposed to various heat conditions. Microstructural evolutions under the complicated heat history should be focused, because they determine the performance of blanket module.

Hideo Sakasegawa; Hiroyasu Tanigawa; Sho Kano; Masato Enomoto

2011-01-01

393

Identification of superfluid phases of 3He in uniformly isotropic 98.2% aerogel.  

PubMed

Superfluid ^{3}He confined to high porosity silica aerogel is the paradigm system for understanding impurity effects in unconventional superconductors. However, a crucial first step has been elusive: exact identification of the microscopic states of the superfluid in the presence of quenched disorder. Using a new class of highly uniform aerogel materials, we report pulsed nuclear magnetic resonance experiments that demonstrate definitively that the two observed superfluid states in aerogel are impure versions of the isotropic and axial p-wave states. The theoretically predicted destruction of long-range orbital order (Larkin-Imry-Ma effect) in the impure axial state is not observed. PMID:22181617

Pollanen, J; Li, J I A; Collett, C A; Gannon, W J; Halperin, W P

2011-10-31

394

Characterization of three fibrous insulations for potential HTGR application  

SciTech Connect

Three fibrous insulation materials manufactured by Babcock and Wilcox were characterized for possible use as HTGR core thermal insulations. These materials (Unifelt 3000 board, Unifelt 2600 board, and Kaowool blanket) were characterized by spectrographic analysis, x-ray diffractometry, scanning electron microscopy, ignition studies and bulk density measurements, resilience tests, helium permeation tests, and compressive stress-strain tests. Of these properties, resilience is the most important for determining acceptability of material for HTGR use. The arbitrary resilience acceptability criterion is 90% or greater after 20 h at 816/sup 0/C (1500/sup 0/F). Based on the resilience test, the Unifelt 3000 was acceptable, the Unifelt 2600 was marginal, and the Kaowool was unacceptable.

Selle, J. E.

1980-11-01

395

Mechanical attachments for flexible blanket TPS  

NASA Astrophysics Data System (ADS)

The operability of a flexible blanket thermal protection system for a reusable launch vehicle can be improved by using mechanical attachments instead of adhesive bonding to fasten the thermal protection system to the vehicle structure. Mechanical attachments offer specific benefits by (1) permitting the use of composite or metal structures at or near their maximum temperatures (above the adhesive temperature limit) thereby reducing the required TPS thickness and weight, (2) significantly reducing both the frequency and time for TPS replacement, (3) providing easy access to hatches and the underlying structure, and (4) allowing the attachment of flexible TPS to integral cryotanks, where the TPS/structure interface temperature may fall below the lower temperature of the silicone adhesives.

Newquist, Charles W.; Anderson, David M.; Shorey, Mark W.; Preedy, Kristina S.

1998-01-01

396

Detect corrosion under insulation  

SciTech Connect

Technology is available to quickly and reliably detect corrosion under insulation (CUI) of piping systems without disturbing the insulation. This technology has permitted many refineries and petrochemical facilities to successfully detect this problem in an expedient and cost-effective manner. CUI is difficult to find because of the insulation cover that masks the corrosion problem until it is too late. It is expensive to remove the insulation, particularly if asbestos is involved. There is a number of methods to inspect for corrosion under insulation. The main ones are profile radiography, ultrasonic spot readings and insulation removal. The other method now available is real-time X-ray. Real-time X-ray has proven to be a safe, fast and effective pipe inspection method.

Twomey, M. [Conam Inspection Inc., Signal Hill, CA (United States)

1997-01-01

397

Development of fusion blanket technology for the DEMO reactor.  

PubMed

The viability of various materials and blanket designs for use in nuclear fusion reactors can be tested using computer simulations and as parts of the test blanket modules within the International Thermonuclear Experimental Reactor (ITER) facility. The work presented here focuses on blanket model simulations using the Monte Carlo simulation package MCNPX (Computational Physics Division Los Alamos National Laboratory, 2010) and FISPACT (Forrest, 2007) to evaluate the tritium breeding capability of a number of solid and liquid breeding materials. The liquid/molten salt breeders are found to have the higher tritium breeding ratio (TBR) and are to be considered for further analysis of the self sufficiency timing. PMID:22112596

Colling, B R; Monk, S D

2011-11-10

398

Disinfection of woollen blankets in steam at subatmospheric pressure  

PubMed Central

Blankets may be disinfected in steam at subatmospheric pressures by temperatures below boiling point inside a suitably adapted autoclave chamber. The chamber and its contents are thoroughly evacuated of air so as to allow rapid heat penetration, and steam is admitted to a pressure of 10 in. Hg below atmospheric pressure, which corresponds to a temperature of 89°C. Woollen blankets treated 50 times by this process were undamaged. Vegetative organisms were destroyed but not spores. The method is suitable for large-scale disinfection of blankets and for disinfecting various other articles which would be damaged at higher temperatures.

Alder, V. G.; Gillespie, W. A.

1961-01-01

399

Molten salt cooling/17Li-83Pb breeding blanket concept  

NASA Astrophysics Data System (ADS)

A description of a fusion breeding blanket concept using draw salt coolant and static (17)Li-(83)Pb is presented. The (17)Li-(83)Pb has high breeding capability and low tritium solubility. Draw salt operates at low pressure and is inert to water. Corrosion, magnetohydrodynamics, and tritium containment problems associated with the design are alleviated because of the use of a static LiPb blanket. Blanket tritium recovery is by permeation toward the plasma. A direct contact steam generator is proposed to eliminate some generic problems associated with a tube shell steam generator.

Sze, D. Z.; Cheng, E. T.

1985-02-01

400

Metal-insulator transitions  

Microsoft Academic Search

Metal-insulator transitions are accompanied by huge resistivity changes, even over tens of orders of magnitude, and are widely observed in condensed-matter systems. This article presents the observations and current understanding of the metal-insulator transition with a pedagogical introduction to the subject. Especially important are the transitions driven by correlation effects associated with the electron-electron interaction. The insulating phase caused by

Masatoshi Imada; Atsushi Fujimori; Yoshinori Tokura

1998-01-01

401

Measuring Wall Insulation  

NASA Astrophysics Data System (ADS)

Currently, the only way for homeowners to learn about the effectiveness of their home insulation is to hire an energy auditor. This difficulty deters homeowners from taking action to improve energy efficiency. We have developed a simple device to measure wall insulation by measuring the temperature difference between the wall surface and the interior air. This device is effective in diagnosing cases of low insulation.

Parks, Beth; Kurkel, Kevin; Zranchev, Amanda; Brown, Clayton

2011-03-01

402

Strong, conductive, lightweight, neat graphene aerogel fibers with aligned pores.  

PubMed

Liquid crystals of anisotropic colloids are of great significance in the preparation of their ordered macroscopic materials, for example, in the cases of carbon nanotubes and graphene. Here, we report a facile and scalable spinning process to prepare neat "core-shell" structured graphene aerogel fibers and three-dimensional cylinders with aligned pores from the flowing liquid crystalline graphene oxide (GO) gels. The uniform alignment of graphene sheets, inheriting the lamellar orders from GO liquid crystals, offers the porous fibers high specific tensile strength (188 kN m kg(-1)) and the porous cylinders high compression modulus (3.3 MPa). The porous graphene fibers have high specific surface area up to 884 m(2) g(-1) due to their interconnected pores and exhibit fine electrical conductivity (2.6 × 10(3) to 4.9 × 10(3) S m(-1)) in the wide temperature range of 5-300 K. The decreasing conductivity with decreasing temperature illustrates a typical semiconducting behavior, and the 3D interconnected network of 2D graphene sheets determines a dual 2D and 3D hopping conduction mechanism. The strong mechanical strength, high porosity, and fine electrical conductivity enable this novel material of ordered graphene aerogels to be greatly useful in versatile catalysts, supercapacitors, flexible batteries and cells, lightweight conductive fibers, and functional textiles. PMID:22799441

Xu, Zhen; Zhang, Yuan; Li, Peigang; Gao, Chao

2012-07-23

403

Deep Bed Adsorption Testing using Silver-Functionalized Aerogel  

SciTech Connect

Nuclear fission results in the production of fission products and activation products, some of which tend to be volatile during used fuel reprocessing and evolve in gaseous species into the reprocessing facility off-gas systems. Analyses have shown that I129, due to its radioactivity, high potential mobility in the environment, and high longevity (half life of 15.7 million years), can require control efficiencies of up to 1,000x or higher to meet regulatory emission limits. Two Aerogel sorption tests that have been performed this fiscal year. The maximum iodine decontamination factor (DF) was measured to be over 10,000, above the 1,000-10,000 target DF range. The mass transfer zone may be as short as 0.5 inches under the sorption conditions of the first test. Only a small fraction of the iodine sorbed on Bed 1 was desorbed during the purge periods. The silver-functionalized Aerogel appears to have potential to be a very effective and efficient iodine sorbent.

Nick Soelberg; Tony Watson

2012-06-01

404

Inelastic scattering from liquid /sup 4/He in aerogel glass  

SciTech Connect

The physics of liquid and solid /sup 4/He in restricted geometries has motivated a number of interesting experiments. Recent experiments include detailed measurements of the phase diagram for bulk liquid in vycor, showing a suppression of the superfluid transition and elevation of the melting pressure, and measurements of the superfluid fraction in vycor, aerogel, and zerogel glasses near the lambda point, in which critical exponents differ from the pure /sup 4/He values have been observed. Many striking features in several of the experiments on helium in restricted geometries are poorly understood. We have performed inelastic neutron scattering measurements of liquid helium in aerogel glass above and below the superfluid transition for two samples of different porosities. The kinetic energy (KE) of the confined liquid is the same as that of the bulk liquid in the normal phase, but is clearly higher than the bulk values in the superfluid phase. The observed scattering in the superfluid phase is more peaked than in the normal phase: consistent with the presence of a Bose condensate. An estimate of the condensate fraction using a modification of a method due to Sears yields values consistent with those estimated for the bulk liquid. 7 refs., 2 figs., 1 tab.

Snow, W.M.; Sokol, P.E.

1988-01-01

405

Gas insulated transmission line with insulators having field controlling recesses  

DOEpatents

A gas insulated transmission line having a novel insulator for supporting an inner conductor concentrically within an outer sheath. The insulator has a recess contiguous with the periphery of one of the outer and inner conductors. The recess is disposed to a depth equal to an optimum gap for the dielectric insulating fluid used for the high voltage insulation or alternately disposed to a large depth so as to reduce the field at the critical conductor/insulator interface.

Cookson, Alan H. (Pittsburgh, PA); Pederson, Bjorn O. (Chelmsford, MA)

1984-01-01

406

Fusion blanket for high-efficiency power cycles  

SciTech Connect

The efficiencies of blankets for fusion reactors are usually in the range of 30 to 40%, limited by the operating temperature (500/sup 0/C) of conventional structural materials such as stainless steels. In this project two-zone blankets are proposed; these blankets consist of a low-temperature shell surrounding a high-temperature interior zone. A survey of nucleonics and thermal hydraulic parameters has led to a reference blanket design consisting of a water-cooled stainless steel shell around a BeO, ZrO/sub 2/ interior (cooled by Ar) utilizing Li/sub 2/O for tritium breeding. In this design, approx. 60% of the fusion energy is deposited in the high-temperature interior. The maximum Ar temperature is 2230/sup 0/C leading to an overall efficiency estimate of 55 to 60% for this reference case.

Usher, J.L.; Powell, J.R.; Fillo, J.A.; Horn, F.L.; Lazareth, O.W.; Taussig, R.

1980-01-01

407

Drag Force on a High Porosity Aerogel in Liquid 3He  

NASA Astrophysics Data System (ADS)

We discuss the drag force exerted on a high porosity aerogel in liquid 3He and its effect on sound propagation. The drag force is governed by distinct laws depending on the Knudsen number Kn, the ratio of the quasiparticle mean free path to a characteristic linear size of a body immersed in liquid. In the liquid 3He-aerogel system, the characteristic length scale is aerogel strand diameter and both of the Knudsen limit (Kn ? 1) and the hydrodynamic limit (Kn ? 1) can be achieved in the normal phase by varying temperature. We show that the crossover between the two limits can be found as a drastic change in the temperature dependence of sound attenuation in the normal phase of liquid 3He in aerogel.

Takeuchi, Hiromitsu; Higashitani, Seiji; Nagai, Katsuhiko

2012-12-01

408

Experiments with ^3He in 10% uniaxially compressed aerogel: the superfluid phase diagram  

NASA Astrophysics Data System (ADS)

Entraining ^3He in aerogel provides a way to introduce disorder in the otherwise ideal quantum fluid. Motivated by the recent prediction that uniaxially compressed aerogel can stabilize the anisotropic A phase over the isotropic B phase, we use a torsional oscillator technique to measure the superfluid phase diagram of ^3He entrained in 10% axially compressed, 98% porous aerogel. We observe that a broad region of the temperature-pressure phase diagram is occupied by the metastable A phase. The reappearance of the A phase on warming from the B phase, before superfluidity is extinguished at Tc, is in contrast to its absence in uncompressed aerogel. We also find that the anticipated alignment of the angular momentum vector by compression is not observed.

Zhelev, Nikolay; Bennett, Robert; Smith, Eric; Pollanen, Johannes; Halperin, William; Parpia, Jeevak

2012-02-01

409

Organic compound alteration during hypervelocity collection of carbonaceous materials in aerogel  

NASA Astrophysics Data System (ADS)

The NASA Stardust mission brought to Earth micron-size particles from the coma of comet 81P/Wild 2 using aerogel, a porous silica material, as the capture medium. A major challenge in understanding the organic inventory of the returned comet dust is identifying, unambiguously, which organic molecules are indigenous to the cometary particles, which are produced from carbon contamination in the Stardust aerogel, and which are cometary organics that have been modified by heating during the particle capture process. Here it is shown that 1) alteration of cometary organic molecules along impact tracks in aerogel is highly dependent on the original particle morphology, and 2) organic molecules on test-shot terminal particles are mostly preserved. These conclusions are based on two-step laser mass spectrometry (L2MS) examinations of test shots with organic-laden particles (both tracks in aerogel and the terminal particles themselves).

Spencer, M. K.; Clemett, S. J.; Sandford, S. A.; McKay, D. S.; Zare, R. N.

2009-03-01

410

Ignition Capsules with Aerogel-Supported Liquid DT Fuel For The National Ignition Facility  

SciTech Connect

For high repetition-rate fusion power plant applications, capsules with aerogel-supported liquid DT fuel can have much reduced fill time compared to {beta}-layering a solid DT fuel layer. The melting point of liquid DT can be lowered once liquid DT is embedded in an aerogel matrix, and the DT vapor density is consequently closer to the desired density for optimal capsule design requirement. We present design for NIF-scale aerogel-filled capsules based on 1-D and 2-D simulations. An optimal configuration is obtained when the outer radius is increased until the clean fuel fraction is within 65-75% at peak velocity. A scan (in ablator and fuel thickness parameter space) is used to optimize the capsule configurations. The optimized aerogel-filled capsule has good low-mode robustness and acceptable high-mode mix.

Ho, D D; Salmonson, J D; Clark, D S; Lindl, J D; Haan, S W; Amendt, P; Wu, K J

2011-10-25

411

Making flexible magnetic aerogels and stiff magnetic nanopaper using cellulose nanofibrils as templates  

NASA Astrophysics Data System (ADS)

Nanostructured biological materials inspire the creation of materials with tunable mechanical properties. Strong cellulose nanofibrils derived from bacteria or wood can form ductile or tough networks that are suitable as functional materials. Here, we show that freeze-dried bacterial cellulose nanofibril aerogels can be used as templates for making lightweight porous magnetic aerogels, which can be compacted into a stiff magnetic nanopaper. The 20-70-nm-thick cellulose nanofibrils act as templates for the non-agglomerated growth of ferromagnetic cobalt ferrite nanoparticles (diameter, 40-120 nm). Unlike solvent-swollen gels and ferrogels, our magnetic aerogel is dry, lightweight, porous (98%), flexible, and can be actuated by a small household magnet. Moreover, it can absorb water and release it upon compression. Owing to their flexibility, high porosity and surface area, these aerogels are expected to be useful in microfluidics devices and as electronic actuators.

Olsson, R. T.; Azizi Samir, M. A. S.; Salazar-Alvarez, G.; Belova, L.; Ström, V.; Berglund, L. A.; Ikkala, O.; Nogués, J.; Gedde, U. W.

2010-08-01

412

Capture of High-Speed Interstellar Dust Analogues in Stardust Flight Spare Aerogel  

NASA Astrophysics Data System (ADS)

We present the results of laboratory campaigns investigating the effects of particle density and composition on the dimensions of tracks created by hypervelocity dust grains hitting Stardust flight spare aerogel collectors.

Trieloff, M.; Postberg, F.; Hillier, J. K.; Armes, S.; Bugiel, S.; Butterworth, A.; Dupin, D.; Fielding, L. A.; Fujii, S.; Gainsforth, Z.; Grün, E.; Li, Y. W.; Srama, R.; Sterken, V.; Stodolna, J.; Westphal, A.

2012-09-01

413

FIRST STEP blanket structure and fuel assembly design  

SciTech Connect

FIRST STEP (Fusion, Inertial, Reduced Requirement Systems Test for Special Nuclear Material, Tritium, and Energy Production) is an Inertial Confinement Fusion (ICF) plant designed to produce tritium, SNM, and energy using near-term technology. It is an integrated facility that will serve as a test bed for fusion power plant technology. The design of the blanket structure and blanket fuel assembly for wetted-wall FIRST STEP reactors is presented here.

Saylor, W.W.; Pendergrass, J.H.; Thayer, G.R.

1984-01-01

414

Dynamic Ordering-Based Search Algorithm for Markov Blanket Discovery  

Microsoft Academic Search

\\u000a Markov blanket discovery plays an important role in both Bayesian network induction and feature selection for classification\\u000a tasks. In this paper, we propose the Dynamic Ordering-based Search algorithm (DOS) for learning a Markov blanket of a domain\\u000a variable from statistical conditional independence tests on data. The new algorithm orders conditional independence tests\\u000a and updates the ordering immediately after a test is

Yifeng Zeng; Xian He; Yanping Xiang; Hua Mao

415

Transient thermal and dynamic stresses in strongback-design blankets  

SciTech Connect

Transient thermal stresses of the first wall are compared for strongback-design blankets that contain stainless steel, ferritic steel, or a vanadium alloy as structural materials. Transient dynamics stresses due to plasma disruptions are computed on a parametric basis. Disruption loading characteristics, for which transient effects are important, are identified. Also explored are the relative merits of supporting the blanket at the top versus the bottom from the standpoint of dynamic stresses.

Majumdar, S.

1994-06-01

416

Evaluation of organic moderator/coolants for fusion breeder blankets  

SciTech Connect

Organic coolants have several attractive features for fusion breeder blanket design. Their apparent compatibility with lithium and their ideal physical and nuclear properties allows straight-forward, high performance designs. Radiolytic damage can be reduced to about the same order as comparable fission systems by using multiplier/stripper blanket designs. Tritium recovery from the organic should be straightforward, but additional data is needed to make a better assessment of the economics of the process.

Romero, J.B.

1980-03-01

417

Conceptual design of a self-cooled Flibe blanket  

Microsoft Academic Search

There are a number of attractive features for Flibe, such as: (1) low-pressure operation, (2) relatively inert to air and water, (3) low activation, (4) high-temperature stability, and (5) low electrical conductivity. If these features can be incorporated into a self-cooled blanket, a simple, high-performance, and reliable blanket may be possible. Detailed analysis has uncovered some attractive features and some

D. K. Sze; E. T. Cheng; J. Jung; S. Piet; A. Klein

1986-01-01

418

Identification of minerals and meteoritic materials via Raman techniques after capture in hypervelocity impacts on aerogel  

SciTech Connect

For this study, an extensive suite of mineral particles analogous to components of cosmic dust were tested to determine if their Raman signatures can be recognized after hypervelocity capture in aerogel. The mineral particles were mainly of greater than 20 micrometers in size and were accelerated onto the silica aerogel by light gas gun shots. It was found that all the individual minerals captured in aerogel could be subsequently identified using Raman (or fluorescent) spectra. The beam spot size used for the laser illumination was of the order of 5 micrometers, and in some cases the captured particles were of a similar small size. In some samples fired into aerogel there was observed a shift in the wavenumbers of some of the Raman bands, a result of the trapped particles being at quite high temperatures due to heating by the laser. Temperatures of samples under laser illumination were estimated from the relative intensities of Stokes and anti-Stokes Raman bands, or, in the case of ruby particles, from the wavenumber of fluorescence bands excited by the laser. It was found that the temperature of particles in aerogel varied greatly, dependent upon laser power and the nature of the particle. In the worst case, some particles were shown to have temperatures in the 500-700 C range at a laser power of about 3 mW at the sample. However most of the mineral particles examined at this laser power had temperatures below 200 C. This is sufficiently low a temperature not to damage most materials expected to be found captured in aerogel in space. In addition, selected meteorite samples were examined to obtain Raman signatures of their constituent minerals and were then shot into aerogel. It was possible to find several Raman signatures after capture in aerogel and obtain a Raman map of a whole grain in situ in the aerogel. Finally, a Raman analysis was carried out of a particle captured in aerogel in space and carbonaceous material identified. In general therefore it is concluded that Raman analysis is indeed well suited for an in-situ analysis of micrometer sized non-terrestrial materials captured in aerogel.

Burchell, M J; Mann, J; Creighton, J A; Kearsley, A; Graham, G A; Esposito, A P; Franchi, I A; Westphal, A J; Snead, C

2004-10-04

419

Polymeric outdoor insulation  

Microsoft Academic Search

The need for resistance to surface tracking and erosion partially differentiates outdoor insulation from indoor insulation. A review of the current status of development of standards for testing these properties worldwide on materials and components is presented. Of special interest is the self-restoration of the hydrophobicity of some materials, most notably silicones, after the hydrophobicity has been removed by surface

W. T. Starr

1990-01-01

420

Improved DC Gun Insulator  

Microsoft Academic Search

Many user facilities such as synchrotron light sources and free electron lasers require accelerating structures that support electric fields of 10-100 MV\\/m, especially at the start of the accelerator chain where ceramic insulators are used for very high gradient DC guns. These insulators are difficult to manufacture, require long commissioning times, and have poor reliability, in part because energetic electrons

M. L. Neubauer; K. B. Beard; R. Sah; C. Hernandez-Garcia; G. Neil

2009-01-01

421

Insulators and Conductors  

NSDL National Science Digital Library

In this activity, learners explore the concept of conducting or insulating electricity. Learners test different everyday materials to determine if the materials are conductors or insulators of electricity. Learners work in teams to test their predictions about each material and then compare results and discuss findings.

Ieee

2013-07-08

422

Surface chemical modification of silica aerogels using various alkyl-alkoxy\\/chloro silanes  

Microsoft Academic Search

The experimental results on the surface chemical modification of silica aerogels using various alkyl-alkoxy\\/chloro silane (organosilane) compounds, are reported. Silica alcogels, prepared by keeping the molar ratio of tetramethoxysilane (TMOS), organosilane compound, methanol (MeOH), water (H2O) and ammonia (NH4OH) constant at 1:0.5:14:4:3.7×10?3 respectively, were dried supercritically to obtain the aerogels. In all, 10 organosilane compounds having zero to three functional

A. Venkateswara Rao; Manish M. Kulkarni; D. P. Amalnerkar; Tanay Seth

2003-01-01

423

Effect of Processing Temperature on Gelation and Physical Properties of Low Density TEOS Based Silica Aerogels  

Microsoft Academic Search

In the present paper the experimental results of the effect of sol-gel processing temperature on the physical properties of\\u000a the TEOS based silica aerogels are reported and discussed. The aerogels were produced by the two step sol-gel process at various\\u000a temperatures in the range of 26–70?;C followed by supercritical drying using methanol solvent extraction. A remarkable reduction in the gelation

NAGARAJA D. HEGDE; A. VENKATESWARA RAO

2006-01-01

424

Physicochemical properties of ambiently dried sodium silicate based aerogels catalyzed with various acids  

Microsoft Academic Search

Experimental results on the physico-chemical properties of ambiently dried sodium silicate based aerogels catalyzed with various\\u000a acids are reported. The aerogels were prepared by hydrolysis and polycondensation of sodium silicate followed by subsequent\\u000a washings, surface chemical modification and ambient pressure drying using 10 various acid catalysts consisting of strong and\\u000a weak acids. The strength and concentration of acids have the

Uzma K. H. Bangi; A. Parvathy Rao; H. Hirashima; A. Venkateswara Rao

2009-01-01

425

Iron-oxide aerogel and xerogel catalyst formulations: Characterization by 57Fe Mössbauer and XAFS spectroscopies  

Microsoft Academic Search

Iron in various iron-oxide aerogel and xerogel catalyst formulations (?85% Fe2O3; ?10% K, Co, Cu, or Pd) developed for possible use in Fischer–Tropsch synthesis (FTS) or the water-gas-shift (WGS) reaction has been examined by 57Fe Mössbauer spectroscopy. The seventeen samples consisted of both as-prepared and calcined aerogels and xerogels and their products after use as catalysts for FTS or the

Frank E. Huggins; Sumit Bali; Gerald P. Huffman; Edward M. Eyring

2010-01-01

426

Monolithic Nickel (II) Oxide Aerogels Using an Organic Epoxide: The Importance of the Counter Ion  

SciTech Connect

The synthesis and characterization of nickel (II) oxide aerogel materials prepared using the epoxide addition method is described. The addition of the organic epoxide propylene oxide to an ethanolic solution of NiCl{sub 2} 6H{sub 2}O resulted in the formation of an opaque light green monolithic gel and subsequent drying with supercritical CO{sub 2} gave a monolithic aerogel material of the same color. This material has been characterized using powder X-ray diffraction, electron microscopy, elemental analysis, and nitrogen adsorption/desorption analysis. The results indicate that the nickel (II) oxide aerogel has very low bulk density (98 kg/m{sup 3} ({approx}98 %porous)), high surface area (413 m{sup 2}/g), and has a particulate-type aerogel microstructure made up of very fine spherical particles with an open porous network. By comparison, a precipitate of Ni{sub 3}(NO{sub 3}){sub 2}(OH){sub 4} is obtained when the same preparation is attempted with the common Ni(NO{sub 3}){sub 2} 6H{sub 2}O salt as the precursor. The implications of the difference of reactivity of the two different precursors are discussed in the context of the mechanism of gel formation via the epoxide addition method. The synthesis of nickel (II) oxide aerogel, using the epoxide addition method, is especially unique in our experience. It is our first example of the successful preparation of a metal oxide aerogel using a metal divalent metal ion and may have implications for the application of this method to the preparation of aerogels or nanoparticles of other divalent metal oxides. To our knowledge this is the first report of a monolithic pure nickel (II) oxide aerogel materials.

Gash, A E; Satcher, J H; Simpson, R L

2004-01-13

427

Synthesis of window glazing coated with silica aerogel films via ambient drying  

Microsoft Academic Search

An ambient drying process (1 atm, 270 °C) has been developed in order to synthesize window glazing coated with silica aerogel films. The aerogel film could be manufactured by this process of wet gel films obtained via a dip-\\/spin-coating of the silica sol on a glass slide. Before drying, the isoproponol solvent in wet gels was exchanged with n-heptane to

Gun-Soo Kim; Sang-Hoon Hyun

2003-01-01

428

Preparation of polyurethane-based aerogels and xerogels for thermal superinsulation  

Microsoft Academic Search

Previous work has demonstrated the feasibility of synthesizing low-density polyurethane- and polyisocyanurate-based aerogels that exhibit low effective thermal conductivity. On the basis of this literature, the present study synthesized and characterized nanostructured polyurethane aerogel-like materials processed via subcritical drying routes. Two families of polyurethane gels were studied. Wet gels were synthesized with two polyols of different functionality. The influence of

A. Rigacci; J. C. Marechal; M. Repoux; M. Moreno; P. Achard

2004-01-01

429

Effect of mixed Catalysts system on TEOS-based silica aerogels dried at ambient pressure  

Microsoft Academic Search

In the present paper, the experimental results on the effect of mixed Catalysts system on the physical properties of the TEOS-based silica aerogels, are reported and discussed. The aerogels were produced by the single-step as well as two-step sol–gel process followed by atmospheric pressure drying. In the single-step process, only the NH4F was used as a catalyst, whereas in the

Jyoti L. Gurav; Digambar Y. Nadargi; A. Venkateswara Rao

2008-01-01

430

Capacitive deionization characteristics of nanostructured carbon aerogel electrodes synthesized via ambient drying  

Microsoft Academic Search

RF (resorcinol formaldehyde) organic aerogels were cost-effectively prepared by solvent exchange using acetone and then ambient drying of RF wet gels obtained from the sol–gel method of the starting solution of RF. The carbon aerogel electrodes for the capacitive deionization (CDI) process with high specific surface area (?610 m2\\/g), high specific capacitance (?220 F\\/g), high porosity (?80%), low bulk density

Hae-Hyun Jung; Sung-Woo Hwang; Sang-Hoon Hyun; Kang-Ho Lee; Gye-Tai Kim

2007-01-01

431

On the chemistry and morphology of titania aerogels derived from sol-gel processing  

NASA Astrophysics Data System (ADS)

Sol-gel processing is used to prepare materials as diverse as catalyst supports, adsorbents, films, fibers, ceramics, and glasses. The advantage of the sol-gel processing is its ability to produce highly pure and homogeneous products at low temperatures. The microstructure of titania gels and surface fractality as well as chemistry of titania aerogels have been systematically investigated in this dissertation. In Part I, various synthetic procedures were described and employed to synthesize polymeric and particulate titania gels. Titania aerogels were prepared via freeze and COsb2 supercritical drying. Part II concerns the development of a novel sample preparation technique for studying titania gel microstructure prior to drying via conventional transmission electron microscopy. This new technique was employed to investigate the microstructure of several titania gels. In Part III, the surface fractality of polymeric and particulate titania aerogels was studied by means of adsorption techniques. Three distinctly different methods, e.g., Avnir and Pfeifer's method, Frenkel-Halsey-Hill method, and the thermodynamic method, were employed to determine the surface fractality. The performances of these three methods were compared. It was found that the fractal surfaces of particulate aerogels are slightly more irregular than those of polymeric aerogels. In addition, the effects of solvent replacement in polymeric titania gels on the surfaces of resultant aerogels were investigated. Solvent replacement resulted in smoothing the surfaces of aerogels obtained from subsequent freeze drying. In Part IV, the effects of catalyst, drying method, and solvent replacement on the chemistry of titania aerogels were analyzed qualitatively via photoacoustic infrared spectroscopy. The utility of photoacoustic technique for obtaining such information was clearly demonstrated. Finally, the conclusions reached and recommendations for future work are presented in Part V.

Meng, Fang

432

FRACTURE OF SILICA AEROGELS: EFFECTS OF SURFACE NATURE ON CRACK PROPAGATION  

Microsoft Academic Search

Silica aerogels show like dense silica a low speed fracture regime under water vapor. This sub-critical crack growth domain is approached by the Double-Cleavage-Drilled-Compression test (DCDC). Because stress corrosion is a surface phenomenon and since water adsorption is affected by the physical properties of silica surface, we investigate hydrophilic aerogels obtained in the same experimental conditions and outgassed under primary

F. DESPETIS; P. ETIENNE; S. ETIENNE-CALAS; J. PHALIPPOU

433

Formation of superfluid liquid pocket in aerogel and its solidification by cooling  

NASA Astrophysics Data System (ADS)

Formation of superfluid liquid pockets of 4He surrounded by 4He crystals were observed in an aerogel of 96% porosity. The liquid pockets did not crystallize by application of pressure but crystallized via avalanche by cooling below a particular temperature. The crystallization by cooling was also observed when crystals occupied a smaller portion of the aerogel. Driving force for the crystallization by cooling and possible mass transport process are discussed.

Matsuda, H.; Ochi, A.; Isozaki, R.; Nomura, R.; Okuda, Y.

2013-09-01

434

Mott-insulator dynamics  

SciTech Connect

The hydrodynamics of a lattice Bose gas in a time-dependent external potential is studied in a mean-field approximation. The conditions under which a Mott insulating region can melt, and the local density can adjust to the new potential, are determined. In the case of a suddenly switched potential, it is found that the Mott insulator stays insulating and the density will not adjust if the switch is too abrupt. This comes about because too rapid currents result in Bloch oscillation-type current reversals. For a stirrer moved through a Mott insulating cloud, it is seen that only if the stirrer starts in a superfluid region and the velocity is comparable to the time scale set by the tunneling will the Mott insulator be affected.

Lundh, Emil [Department of Physics, Umeaa University, 901 87 Umeaa (Sweden)

2011-09-15

435

Topological Anderson insulator.  

PubMed

Disorder plays an important role in two dimensions, and is responsible for striking phenomena such as metal-insulator transition and the integral and fractional quantum Hall effects. In this Letter, we investigate the role of disorder in the context of the recently discovered topological insulator, which possesses a pair of helical edge states with opposing spins moving in opposite directions and exhibits the phenomenon of quantum spin Hall effect. We predict an unexpected and nontrivial quantum phase termed "topological Anderson insulator," which is obtained by introducing impurities in a two-dimensional metal; here disorder not only causes metal-insulator transition, as anticipated, but is fundamentally responsible for creating extended edge states. We determine the phase diagram of the topological Anderson insulator and outline its experimental consequences. PMID:19392389

Li, Jian; Chu, Rui-Lin; Jain, J K; Shen, Shun-Qing

2009-04-01

436

Non-supercritically dried silica–silica composite aerogel and its possible application for confining simulated nuclear wastes  

Microsoft Academic Search

The simpler non-supercritical drying approach has been used for the first time for the preparation of silica–silica composite\\u000a aerogels (CA) and the efficiency of the process being demonstrated by testing the use of the aerogels for simulated high level\\u000a nuclear waste confinement. Compositions of 5, 10, 20, 30, 40 and 50 wt% of silica (aerosil® 380) in silica–aerogel were prepared\\u000a by

P. R. Aravind; P. Shajesh; P. Mukundan; P. Krishna Pillai; K. G. K. Warrier

2008-01-01

437

Synthesis and characterization of vanadium oxide aerogels. Technical report No. 2, 1 June 1994-31 May 1995  

Microsoft Academic Search

Vanadium pentoxide aerogels were synthesized by supercritical drying with CO2. The aerogels were prepared using a variety of sol compositions from the system VO(OC3H7)3\\/H2O\\/acetone. The materials were found to be of fairly low density (0.04g\\/cu cm to 0.lg\\/cu cm) with surface areas in the range of 300 to 400 meters squared\\/g. Chemical and structural studies indicate that the aerogels are

F. Chaput; B. Dunn; P. Fuqua; K. Salloux

1995-01-01

438

Iron Aerogel and Xerogel Catalysts for Fischer-Tropsch Synthesis of Diesel Fuel  

SciTech Connect

Iron aerogels, potassium-doped iron aerogels, and potassium-doped iron xerogels have been synthesized and characterized and their catalytic activity in the Fischer-Tropsch (F-T) reaction has been studied. Iron aerogels and xerogels were synthesized by polycondensation of an ethanolic solution of iron(III) chloride hexahydrate with propylene oxide which acts as a proton scavenger for the initiation of hydrolysis and polycondensation. Potassium was incorporated in the iron aerogel and iron xerogel by adding aqueous K{sub 2}CO{sub 3} to the ethanolic solutions of the Fe(III) precursor prior to addition of propylene oxide. Fischer-Tropsch activities of the catalysts were tested in a fixed bed reactor at a pressure of 100 psi with a H{sub 2}:CO ratio of 2:1. Iron aerogels were found to be active for F-T synthesis, and their F-T activities increased on addition of a K containing promoter. Moessbauer spectroscopic data are consistent with an open, nonrigid iron(III) aerogel structure progressing to an iron carbide/metallic iron catalyst via agglomeration as the F-T synthesis proceeds in the course of a 35 h fixed bed reaction test.

Bali, S.; Huggins, F; Huffman, G; Ernst, R; Pugmire, R; Eyring, E

2009-01-01

439

Fine-grained material of 81P/Wild 2 in interaction with the Stardust aerogel  

NASA Astrophysics Data System (ADS)

The deceleration tracks in the Stardust aerogel display a wide range of morphologies, which reveal a large diversity of incoming particles from comet 81P/Wild 2. If the large and dense mineral grains survived the extreme conditions of hypervelocity capture, this was not the case for the fine-grained material that is found strongly damaged within the aerogel. Due to their low mechanical strength, these assemblages were disaggregated, dispersed, and flash melted in the aerogel in walls of bulbous deceleration tracks. Their petrologic and mineralogical properties are found significantly modified by the flash heating of the capture. Originating from a quenched melt mixture of comet material and aerogel, the representative microstructure consists of silica-rich glassy clumps containing Fe-Ni-S inclusions, vesicles and "dust-rich" patches, the latter being remnants of individual silicate components of the impacting aggregate. The average composition of these melted particle fragments is close to the chondritic CI composition. They might originate from ultrafine-grained primitive components comparable to those found in chondritic porous IDPs. Capture effects in aerogel and associated sample biases are discussed in terms of size, chemical and mineralogical properties of the grains. These properties are essential for the grain survival in the extremely hot environment of hypervelocity impact capture in aerogel, and thus for inferring the correct properties of Wild 2 material.

Leroux, Hugues

2012-04-01

440

Mesoporous TiO2 aerogel for selective enrichment of phosphopeptides in rat liver mitochondria.  

PubMed

The enrichment of low abundance phosphopeptides before MS analysis is a critical step for in-depth phosphoproteome research. In this study, mesoporous titanium dioxide (TiO(2)) aerogel was prepared by precipitation and supercritical drying. The specific surface area up to 490.7 m(2) g(-1) is achieved by TiO(2) aerogel, much higher than those obtained by commercial TiO(2) nanoparticles and by the latest reported mesoporous TiO(2) spheres. Due to the large specific surface area and the mesoporous structure of the aerogel, the binding capacity for phosphopeptides is six times higher than that of conventional TiO(2) microparticles (173 vs 28 ?mol g(-1)). Because of the good compatibility of enrichment procedure with MALDI-TOF-MS and the large binding capacity of TiO(2) aerogel, a detection limit as low as 30 amol for analyzing phosphopeptides in ?-casein digest was achieved. TiO(2) aerogel was further applied to enrich phosphopeptides from rat liver mitochondria, and 266 unique phosphopeptides with 340 phosphorylation sites, corresponding to 216 phosphoprotein groups, were identified by triplicate nanoRPLC-ESI-MS/MS runs, with false-positive rate less than 1% at the peptide level. These results demonstrate that TiO(2) aerogel is a kind of promising material for sample pretreatment in the large-scale phosphoproteome study. PMID:22595430

Zhang, Liyuan; Liang, Zhen; Yang, Kaiguang; Xia, Simin; Wu, Qi; Zhang, Lihua; Zhang, Yukui

2012-04-12

441

Three-dimensional arrayed amino aerogel biochips for molecular recognition of antigens.  

PubMed

The three-dimensional (3D) biochips prepared in this study are composed of a glass microscopy slide arrayed with amino aerogel dots. The amino aerogel was produced using the sol-gel process, with an ionic liquid as the template followed by a solvent extraction to remove the template and build a three-dimensional mesoporous structure. The FTIR spectrum verified that the major template was removed and the (29)Si solid-state NMR spectra recognized the cross-linkages in the SiO(2) network structure. SEM images measured the particles at around 100 nm. After grinding, the BET analysis confirmed that the nano-size amino aerogel powders had exhibited specific surface area of 188 m(2)/g, pore volume of 0.83 cm(3)/g, and average pore size of 16.2 nm. The as-prepared amino aerogel surface contained amino functional groups capable of performing a sandwich immunoassay. The primary antibody was immobilized on the internal surface of the arrayed amino aerogel to capture its affinity antigen. On the top of the captured antigen, the report antibody was read its labeling fluorescent dye. In comparison to the corresponding two-dimensional (2D) biochip, the 3D amino aerogel biochips were observed to amplify signal intensities more effectively due to their remarkable capturing capability. PMID:21783248

Li, Yen K; Chen, Yun-Chu; Jiang, Kai-Jen; Wu, Jui-chuang; Chen-Yang, Yui W

2011-07-23

442

Capillary Condensation of Liquid 4He in Aerogel on Cooling Through {lambda} Point  

SciTech Connect

Capillary condensation of liquid 4He in silica aerogel with a 90% porosity was investigated visually. The initial condition of the experiment was such that liquid 4He was present in the sample cell but not in the aerogel. This situation was realized by introducing the liquid into the cell at a fast rate to avoid liquefaction in the aerogel. The free surface of the liquid rose up in the cell with filling and eventually reached the bottom of the aerogel. Then, the aerogel absorbed the liquid by capillary condensation. The height of the liquid in the aerogel rose with time t roughly as t1/2 in the normal fluid phase. This behavior was consistent with the Washburn model. When the system was cooled through the {lambda} point during the condensation, the liquid height started to rise faster in the superfluid phase with a constant velocity of about 0.3 mm/sec. The dynamics of capillary condensation was strongly dependent on whether the liquid 4He was in the normal or the superfluid phase.

Miyashita, W.; Yoneyama, K.; Kato, H.; Nomura, R.; Okuda, Y. [Department of Condensed Matter Physics, Tokyo Institute of Technology, 2-12-1, O-okayama, Meguro, Tokyo 152-8551 (Japan)

2006-09-07

443

APT Blanket System Loss-of-Helium-Gas Accident Based on Initial Conceptual Design - Helium Supply Rupture into Blanket Module  

SciTech Connect

The model results are used to determine if beam power shutdown is necessary (or not) as a result of the LOHGA accident to maintain the blanket system well below any of the thermal-hydraulic constraints imposed on the design. The results also provide boundary conditions to the detailed bin model to study the detailed temperature response of the hot blanket module structure. The results for these two cases are documented in the report.

Hamm, L.L.

1998-10-07

444

The Preservation of Cometary Organics in Stardust Aerogel  

NASA Astrophysics Data System (ADS)

It has been recognized for many years that the continuous global accretion of organic matter from comets and carbonaceous asteroids, over geological timescales, to the surfaces of both Earth and Mars may have played a significant role in the prebiotic chemical evolution of these planets [1]. The dominant mass fraction of accreted meteoritic material is in the form of interplanetary dust for which the current accretion rate is estimated at ˜ 40±20 Gg·yr-1 [2]. Our understanding of the organic matter present in interplanetary dust is, however, limited by the analytical challenges involved in the molecular analysis of heterogeneous micron sized particles. We have used the technique of ultrafast two-step laser mass spectrometry (µltra-L2 MS) to investigate the nature and distribution of the aromatic organic matter present in individual dust particles from comet P81/Wild 2 collected in aerogel by the STARDUST sample return mission [3]. Complex aromatic hydrocarbons have been detected in cometary particles entrained along multiple aerogel tracks. Although terrestrial contamination from the aerogel remains a concern, a substantial fraction is interpreted as indigenous. The spectral complexity is atypical of carbonaceous and ordinary chondrites. While simple fused ring polycyclic aromatic hydrocarbon (PAHs) such as naphthalene (C10 H8 ), acenaphthalene (C12 H8 ), phenanthrene (C14 H10 ) are present along with their homologous alkylation series (Ar-(CH2 )n -H) there are additionally many prominent odd-mass species present. These are consistent with several interleaved alkylation series of N-containing PAHS (NPAHs) in the form of nitriles (Ar-CN). These species may be related to the 2.3 & 4.6 µm 'XCN' adsorption features observed in the spectra of many young stellar objects and some comets, which is believed to be synthesized by ultraviolet and/or ion bombardment of precometary ices in circumstellar environments. The presence of organo-N species is of particular importance to the organic inventory of the the early Earth since its abiotic synthesis would have been extremely slow due to the difficulty in cleaving the N?N triple bond in the absence of biology. [1] Anders (1989) Nature 342, 255; [2] Love & Brownlee (1993) Science 262, 550; Clemett et al. MAPS (submited)

Clemett, Simon; Nakamura-Messenger, Keiko; Sandford, Scott; McKay, David

445

Nano-sized Mn-doped activated carbon aerogel as electrode material for electrochemical capacitor: effect of activation conditions.  

PubMed

Carbon aerogel (CA) was prepared by a sol-gel polymerization of resorcinol and formaldehyde, and a series of activated carbon aerogels (ACA-KOH-X, X = 0, 0.3, 0.7, 1, and 2) were then prepared by a chemical activation using different amount of potassium hydroxide (X represented weight ratio of KOH with respect to CA). Specific capacitances of activated carbon aerogels were measured by cyclic voltammetry and galvanostatic charge/discharge methods in 6 M KOH electrolyte. Among the samples prepared, ACA-KOH-0.7 showed the highest specific capacitance (149 F/g). In order to combine excellent electrochemical performance of activated carbon aerogel with pseudocapacitive property of manganese oxide, 7 wt% Mn was doped on activated carbon aerogel (Mn/ACA-KOH-0.7) by an incipient wetness impregnation method. For comparison, 7 wt% Mn was also impregnated on carbon aerogel (Mn/ACA-KOH-0) by the same method. It was revealed that 7 wt% Mn-doped activated carbon aerogel (Mn/ACA-KOH-0.7) showed higher specific capacitance than 7 wt% Mn-doped carbon aerogel (Mn/ACA-KOH-0) (178 F/g vs. 98 F/g). The enhanced capacitance of Mn/ACA-KOH-0.7 was attributed to the outstanding electric properties of activated carbon aerogel as well as the faradaic redox reactions of manganese oxide. PMID:22966708

Lee, Yoon Jae; Park, Hai Woong; Park, Sunyoung; Song, In Kyu

2012-07-01

446

Experimental study of the influences of degraded vacuum on multilayer insulation blankets  

Microsoft Academic Search

The paper presented experimental investigation on the heat transfer of MLI with different rarefied gases at different pressures. The investigations were carried out using an innovative static liquid nitrogen boil-off rate measurement system in the case of the small temperature perturbations of cold and warm boundaries. The heat fluxes for a number of inert and some polyatomic gases have been

P. J. Sun; J. Y. Wu; P. Zhang; L. Xu; M. L. Jiang

2009-01-01

447

Safety Evaluation of the EVOLVE Blanket Concept  

SciTech Connect

This article summarizes the results of the safety evaluation of the Evaporation of Lithium and Vapor Extraction (EVOLVE) W-alloy first wall (FW) and blanket concept. We have analyzed the EVOLVE design response during a confinement bypass accident. A confinement bypass accident was chosen because, based on previous safety studies, this accident can produce environmental releases by breaching the primary radioactive confinement boundary of EVOLVE, which is the EVOLVE vacuum vessel (VV). As a consequence of a bypass accident, air from a room adjoining the reactor enters the plasma chamber by way of a failed VV port. This air reacts with the high temperature metals inside of the VV to release energy in the case of a lithium spill, or to mobilize radioactive material by oxidation, and then transport this material to the environment by natural convection airflow through the failed VV port. We use the MELCOR code to analyze the response of EVOLVE during this accident. Based on these results, the EVOLVE concept can meet the no-evacuation dose goal set by the DOE Fusion Safety Standard if the EVOLVE confinement building ventilation system is closed within two hours of the onset of this accident.

Merrill, B.J. [Idaho National Engineering and Environmental Laboratory (United States); Marshall, T.D. [Idaho National Engineering and Environmental Laboratory (United States); Khater, H.Y. [University of Wisconsin (United States); Malang, S. [Forschungszentum Karlsruhe GmbH (Germany); Wong, C.P.C. [General Atomics (United States)

2003-09-15

448

Structure-Property Relationships in Porous 3-D Nanostructures as a Function of Preparation Conditions: Isocyanate Cross-Linked Silica Aerogels.  

National Technical Information Service (NTIS)

Sol-gel derived silica aerogels are attractive candidates for many unique thermal, optical, catalytic, and chemical applications because of their low density and high mesoporosity. However, their inherent fragility has restricted use of aerogel monoliths ...

D. S. Papadopoulos L. McCorkle L. A. Capadona M. A. B. Meador N. Leventis

2007-01-01

449

Chitosan bio-based organic-inorganic hybrid aerogel microspheres.  

PubMed

Recently, organic-inorganic hybrid materials have attracted tremendous attention thanks to their outstanding properties, their efficiency, versatility and their promising applications in a broad range of areas at the interface of chemistry and biology. This article deals with a new family of surface-reactive organic-inorganic hybrid materials built from chitosan microspheres. The gelation of chitosan (a renewable amino carbohydrate obtained by deacetylation of chitin) by pH inversion affords highly dispersed fibrillar networks shaped as self-standing microspheres. Nanocasting of sol-gel processable monomeric alkoxides inside these natural hydrocolloids and their subsequent CO(2) supercritical drying provide high-surface-area organic-inorganic hybrid materials. Examples including chitosan-SiO(2), chitosan-TiO(2), chitosan-redox-clusters and chitosan-clay-aerogel microspheres are described and discussed on the basis of their textural and structural properties, thermal and chemical stability and their performance in catalysis and adsorption. PMID:22689451

El Kadib, Abdelkrim; Bousmina, Mosto

2012-06-11

450

Anisotropy of Silica Aerogels Induced by Small Strain  

NASA Astrophysics Data System (ADS)

We have performed optical birefringence measurements on isotropic aerogel samples grown with varying amounts of ammonia catalyst to determine the relationship between stress, strain, and transmitted light intensity, focusing on the regime of relatively small axial strain. We find that our samples exhibit a delayed onset of birefringence at ˜3 % strain, beyond which the transmitted intensity increases linearly, with a faster rate of increase for samples prepared with larger catalyst concentrations. We have also calculated the sound velocity from the slope of the stress-strain curve, and found an approximately linear increase with catalyst solution pH for samples of similar density. Samples of similar density also appear to exhibit a universal relationship between applied stress and transmitted intensity. We are not able to identify the mechanism for this unique behavior.

Zimmerman, A. M.; Specht, M. G.; Ginzburg, D.; Pollanen, J.; Li, J. I. A.; Collett, C. A.; Gannon, W. J.; Halperin, W. P.

2013-06-01

451

Insulation fact sheet  

SciTech Connect

Electricity bills, oil bills, gas bills - all homeowners pay for one or more of these utilities, and wish they paid less. Often many of us do not really know how to control or reduce our utility bills. We resign ourselves to high bills because we think that is the price we have to pay for a comfortable home. We encourage our children to turn off the lights and appliances, but may not recognize the benefits of insulating the attic. This publication provides facts relative to home insulation. It discusses where to insulate, what products to use, the decision making process, installation options, and sources of additional information.

NONE

1997-08-01

452

Outdoor HV composite polymeric insulators  

Microsoft Academic Search

HV composite polymeric insulators are being accepted increasingly for use in outdoor installations by the traditionally cautious electric power utilities worldwide. They currently represent ~60 to 70% of newly installed HV insulators in North America. The tremendous growth in the applications of non-ceramic composite insulators is due to their advantages over the traditional ceramic and glass insulators. These include light

R. Hackam

1999-01-01

453

Insulated Structural Bushings.  

National Technical Information Service (NTIS)

An electrically insulated, structurally strong bushing for use at the chassis mounting interface of an electronic chassis, especially a Low Power RF chassis requiring a single point electrical ground, includes a specially machined epoxy-glass bushing with...

J. J. Chino

1979-01-01

454

Cooper Pairs in Insulators?!  

SciTech Connect

Nearly 50 years elapsed between the discovery of superconductivity and the emergence of the microscopic theory describing this zero resistance state. The explanation required a novel phase of matter in which conduction electrons joined in weakly bound pairs and condensed with other pairs into a single quantum state. Surprisingly, this Cooper pair formation has also been invoked to account for recently uncovered high-resistance or insulating phases of matter. To address this possibility, we have used nanotechnology to create an insulating system that we can probe directly for Cooper pairs. I will present the evidence that Cooper pairs exist and dominate the electrical transport in these insulators and I will discuss how these findings provide new insight into superconductor to insulator quantum phase transitions.

Valles, James (Brown University)

2008-07-23

455

Evaluation of mineralogical alteration of micrometeoroid analog materials captured in aerogel  

NASA Astrophysics Data System (ADS)

Silica aerogel has been used as a capturing medium for micrometeoroids and space debris. Several previous investigations suggest that aerogel could capture hypervelocity particles macroscopically intact. However, it has not been fully evaluated whether retrieved grains retain their pristine mineralogy. This study attempts to evaluate the intact survivability of high-speed projectiles in aerogel using impact experiments. Such experiments are essential for rigorous examination or further scientific discussion on the samples of on-going and future sample return missions in which aerogels are/will be used as capturing media. We fired two kinds of micrometeoroid analog materials into aerogel with a two-stage light gas gun (2-4 km/s), serpentine and cronstedtite, which are commonly found in CM/CI, and CM chondrites, respectively. As these hydrated minerals are broken down into anhydrous ones at relatively low temperatures, it is suitable for the evaluation of thermal alteration during the capturing process. The retrieved residues were examined with SEM/EDS, Synchrotron Radiation-XRD, and TEM/EDS. The SR-XRD analysis revealed that most of the volumes of residues are mineralogically unaltered. TEM observations show that one serpentine grain shot at 4 km/s has an unaltered crystalline part inside, an amorphous layer, and the outermost molten aerogel layer. One cronstedtite grain shot at 3 km/s, also examined by TEM, was found to have an unaltered interior as well as a vesiculated silicate melt layer. Image analysis revealed both mineral grains reduced their volume down to 10% of the original on average. These results suggest that it is possible to capture serpentine and cronstedtite particles mineralogically intact with the aerogel, at least in the interior of each particle, below 4 km/s, in spite of their large volume loss.

Okudaira, K.; Noguchi, T.; Nakamura, T.; Sugita, S.; Sekine, Y.; Yano, H.

2004-01-01

456

High Power Density Blanket Design Study for Fusion Reactors  

NASA Astrophysics Data System (ADS)

A conceptual design study of a high power density blanket has been carried out. The Fusion Experimental Breeder, FEB, is adopted as the reference reactor. The neutron wall loading is 0.5 MW/m2. The blanket is cooled by 10 MPa helium in tube. The concept of LiPb eutectic/transuranium oxide suspension is adopted. The neutronics design is performed to provide the design basis, and it gives an energy multiplication of 37 and a flattened power density distribution with a peak value of 70 W/m3. Multiple cooling panels are introduced to reduce the peak temperature of the blanket. In spite of up to 15 cooling panels, the blanket module is calculated using the ANSYS code and analytically as well. The results are consistent with each other and can meet the thermal criteria. However, structural calculation results from ANSYS did not satisfy the criterion: The blanket structure design is then improved by using curved cooling panels to model the structure in detail. Temperature distribution is obtained using the Pro/Mechanica code. Detailed structural analyses are also done by this code. Some satisfactory results are obtained.

Huang, J. H.; Zhu, Y. K.; Deng, P. Zh.

2003-06-01

457

Overview of design activities for Li/V blankets  

SciTech Connect

Recent fusion power plant design studies in the US have been conducted within the ARIES project. The most recent design of Li/V blankets was conducted as part of the ARIES-RS design. The ARIES-RS fusion power plant design study is based on reversed-shear (RS) physics with a Li/V (lithium breeder and vanadium structure) blanket. The reversed-shear discharge has been documented in many large tokamak experiments. The plasma in the RS mode has a high beta, low current, and low current drive requirement. Therefore, it is an attractive physics regime for a fusion power plant. The blanket system based on a Li/V has high temperature operating capability, good tritium breeding, excellent high heat flux removal capability, long structural life time, low activation, low after heat and good safety characteristics. For these reasons, the ARIES-RS reactor study selected Li/V as the reference blanket. The combination of attractive physics and attractive blanket engineering is expected to result in a superior power plant design.

Sze, D.K.; Mattas, R.F.

1997-12-31

458

Slurry blankets for D-T fusion reactors  

SciTech Connect

A brief overview of the blanket design problem is followed by a general model for fusion power plants based on tritium material balances. This model is used to determine the relationships between important design parameters including doubling time, plant tritium inventory, tritium breeding ratio, and tritium burn rate. A novel concept, the Poor Blanket is then described along with the results of neutron transport calculations that indicate that slurries of Li/sub 2/O particles in molten flibe (LiF-BeF/sub 2/) would provide adequate tritium breeding rates. A preliminary design study of a Pool Blanket is reported for a spheromak reactor in which a Li/sub 2/O slurry is both a breeder and the heat transfer medium. Laboratory experiments indicate that the tritium would exist primarily in the molten salt phase. The results of these studies indicate that the Pool Blanket with a slurry breeder would be an attractive choice for first generation fusion reactors. Calculations of the tritium breeding ratios for slurries of Li/sub 2/O in molten LiF-NaF (a salt that is less toxic than those that contain Be) indicate that such systems merit further investigation. A brief study of neutron multipliers for fusion reactor blankets indicates that Be is by far the best material in that respect. Finally, the results of some density and viscosity measurements for slurries of Li/sub 2/O in molten flibe are reported.

Kasturirangan, T.M.

1985-01-01

459

Photonic Floquet topological insulators  

NASA Astrophysics Data System (ADS)

Topological insulators are a new phase of matter, with the striking property that conduction of electrons occurs only on the surface. In two dimensions, surface electrons in topological insulators do not scatter despite defects and disorder, providing robustness akin to superconductors. Topological insulators are predicted to have wideranging applications in fault-tolerant quantum computing and spintronics. Recently, large theoretical efforts were directed towards achieving topological insulation for electromagnetic waves. One-dimensional systems with topological edge states have been demonstrated, but these states are zero-dimensional, and therefore exhibit no transport properties. Topological protection of microwaves has been observed using a mechanism similar to the quantum Hall effect, by placing a gyromagnetic photonic crystal in an external magnetic field. However, since magnetic effects are very weak at optical frequencies, realizing photonic topological insulators with scatterfree edge states requires a fundamentally different mechanism - one that is free of magnetic fields. Recently, a number of proposals for photonic topological transport have been put forward. Specifically, one suggested temporally modulating a photonic crystal, thus breaking time-reversal symmetry and inducing one-way edge states. This is in the spirit of the proposed Floquet topological insulators, where temporal variations in solidstate systems induce topological edge states. Here, we propose and experimentally demonstrate the first external field-free photonic topological insulator with scatter-free edge transport: a photonic lattice exhibiting topologically protected transport of visible light on the lattice edges. Our system is composed of an array of evanescently coupled helical waveguides arranged in a graphene-like honeycomb lattice. Paraxial diffraction of light is described by a Schrödinger equation where the propagation coordinate acts as `time'. Thus the waveguides' helicity breaks zreversal symmetry in the sense akin to Floquet Topological Insulators. This structure results in scatter-free, oneway edge states that are topologically protected from scattering.

Rechtsman, Mikael C.; Zeuner, Julia M.; Plotnik, Yonatan; Lumer, Yaakov; Podolsky, Daniel; Dreisow, Felix; Nolte, Stefan; Segev, Mordechai; Szameit, Alexander

2013-09-01

460

Insulator for laser housing  

DOEpatents

The present invention provides a heat-resistant electrical insulator adapted for joining laser housing portions, which insulator comprises: an annulus; a channel in the annulus traversing the circumference and length of the housing; at least two ports, each communicating with the channel and an outer surface of the housing; and an attachment for securely attaching each end of the annulus to a laser housing member.

Duncan, David B. (Auburn, CA)

1992-01-01

461

ASRM Case Insulation development  

Microsoft Academic Search

The ASRM Case Insulation Program used design of experiments to develop a high performance case insulation. The program traded-off more than thirty properties in areas of ablation performance, material properties, processibility, bonding\\/aging. Kevlar pulp was found to be the most significant factor. The low-molecular weight ethylene propylene diene monomer, EPDM was the second most significant factor. The curative was the

W. F. S. Tam; M. Bell

1993-01-01

462

Modulated Floquet topological insulators.  

PubMed

The application of spatially uniform light on conventional insulators can induce Floquet spectra with characteristics akin to those of topological insulators. We demonstrate that spatial modulation of light allows for remarkable control of the properties in these systems. We provide configurations to generate one-dimensional bulk modes, photoinduced currents, as well as fractionalized excitations. We show a close analogy to p-wave superconductors and use this analogy to explain our results. PMID:23383821

Katan, Yaniv Tenenbaum; Podolsky, Daniel

2013-01-02

463

Modulated Floquet Topological Insulators  

NASA Astrophysics Data System (ADS)

The application of spatially uniform light on conventional insulators can induce Floquet spectra with characteristics akin to those of topological insulators. We demonstrate that spatial modulation of light allows for remarkable control of the properties in these systems. We provide configurations to generate one-dimensional bulk modes, photoinduced currents, as well as fractionalized excitations. We show a close analogy to p-wave superconductors and use this analogy to explain our results.

Katan, Yaniv Tenenbaum; Podolsky, Daniel

2013-01-01

464

Insulator for laser housing  

DOEpatents

The present invention provides a heat-resistant electrical insulator adapted for joining laser housing portions, which insulator comprises: an annulus; a channel in the annulus traversing the circumference and length of the housing; at least two ports, each communicating with the channel and an outer surface of the housing; and an attachment for securely attaching each end of the annulus to a laser housing member. 3 figs.

Duncan, D.B.

1992-12-29

465

Topological magnon insulator in insulating ferromagnet  

NASA Astrophysics Data System (ADS)

In the ferromagnetic insulator with the Dzyaloshinskii-Moriya interaction, we theoretically predict and numerically verify a topological magnon insulator, where the charge-free magnon is topologically protected for transporting along the edge/surface while it is insulating in the bulk. The chiral edge states form a connected loop as a 4?- or 8?-period Möbius strip in the spin-wave vector space, showing the nontrivial topology of magnonic bands. Using the nonequilibrium Green's function method, we explicitly demonstrate that the one-way chiral edge transport is indeed topologically protected from defects or disorders. Moreover, we show that the topological edge state mainly localizes around edges and leaks into the bulk with oscillatory decay. Although the chiral edge magnons and energy current prefer to travel along one edge from the hot region to the cold one, the anomalous transports are identified in the opposite edge, which reversely flow from the cold region to the hot one. Our findings could be validated within wide energy ranges in various magnonic crystals, such as Lu2V2O7.

Zhang, Lifa; Ren, Jie; Wang, Jian-Sheng; Li, Baowen

2013-04-01

466

Blanket-relevant liquid metal MHD channel flows: data base and optimization simulation development  

Microsoft Academic Search

The problems of generalization and integration of test, theoretical and design data relevant to liquid metal (LM) blanket are discussed in present work. First results on MHD data base and LM blanket optimization codes are presented

I. A. Evtushenko; I. R. Kirillov; S. I. Sidorenkov

1995-01-01

467

75 FR 19954 - Cheniere Marketing, LLC; Application for Blanket Authorization To Export Liquefied Natural Gas  

Federal Register 2010, 2011, 2012, 2013

...Docket No. 10-31-LNG] Cheniere Marketing, LLC; Application for Blanket Authorization...filed on March 23, 2010, by Cheniere Marketing, LLC (CMI), requesting blanket authorization...to reflect a name change from Cheniere Marketing, Inc to Cheniere Marketing,...

2010-04-16

468

78 FR 4400 - Eni USA Gas Marketing LLC; Application for Blanket Authorization To Export Previously Imported...  

Federal Register 2010, 2011, 2012, 2013

...FE Docket No. 12-161-LNG] Eni USA Gas Marketing LLC; Application for Blanket Authorization To...filed on November 8, 2012, by Eni USA Gas Marketing LLC (Eni USA Gas Marketing), requesting blanket authorization to...

2013-01-22

469

77 FR 76013 - Sempra LNG Marketing, LLC; Application for Blanket Authorization To Export Previously Imported...  

Federal Register 2010, 2011, 2012, 2013

...FE Docket No. 12-155-LNG] Sempra LNG Marketing, LLC; Application for Blanket Authorization...filed on October 26, 2012, by Sempra LNG Marketing, LLC (Sempra LNG Marketing), requesting blanket authorization to...

2012-12-26

470

Nuclear-Radiation-Actuated Valve for Increasing Coolant Flow to Blanket).  

National Technical Information Service (NTIS)

The present invention relates to a breeder reactor blanket fuel assembly coolant system valve which increases coolant flow to the blanket fuel assembly to minimize long-term temperature increases caused by fission of fissile fuel created from fertile fuel...

D. W. Christiansen D. P. Schively

1982-01-01

471

Intersubassembly fuel penetration into a failed blanket subassembly. [LMFBR  

SciTech Connect

This work provides additional understanding of hypothetical core-disruptive accident issues involving LMFBRs. Intersubassembly molten fuel and steel penetration into a failed blanket subassembly was analyzed with the two-dimensional SIMMER-II code. Interaction of the fuel and steel with the blanket coolant was included in the investigation. The molten core material was injected through a prescribed opening in the blanket subassembly wall. Eighteen cases involving variations of parameters of importance to the subsequent flow were calculated. In general the resulting pressurization was a good figure of merit for rating the severity of the events. In turn, the pressurization depended on the wall opening size, the initial pool pressure, and the heat-transfer rates. However, only when the wall failure rate was large relative to the sodium expulsion rate, was sufficient pressure generated that could affect the reactor vessel containment.

DeVault, G.P.; Bell, C.R.

1982-08-01

472

Rotating liquid blanket with no first wall for fusion reactors  

SciTech Connect

A toroidal vortex of liquid FLiBe (LiF + BeF/sub 2/) is suggested for the blanket of a fusion reactor. Because this reactor chamber has no solid first wall, it might avoid many of the problems that accompany conventional blanket design. The liquid blanket is sustained by nozzles that inject a continuous layer of cool liquid on the inner surface. A second set of nozzles sends a stream of droplets across the diverted scape-off layer or edge plasma to carry its heat away. The feasibility issues of most importance are judged to be avoiding turbulent breakup of the vortex and preventing too much contamination of the plasma by the evaporating FLiBe.

Moir, R.W.

1989-03-01

473

Rotating liquid blanket with no first wall for fusion reactors  

SciTech Connect

A toroidal vortex of liquid FLiBe (LiF + BeF/sub 2/) is suggested for the blanket of a fusion reactor. Because this reactor chamber has no solid first wall, it might avoid many of the problems that accompany conventional blanket design. The liquid blanket is sustained by nozzles that inject a continuous layer of cool liquid on the inner surface. A second set of nozzles sends a stream of droplets across the diverted scrape-off layer or edge plasma to carry its heat away. The feasibility issues of most importance are judged to be avoiding turbulent breakup of the vortex and preventing too much contamination of the plasma by the evaporating FliBe. 7 refs., 5 figs., 1 tabs.

Moir, R.W.

1988-11-18

474

Influence of molar ratios of precursor, solvent and water on physical properties of citric acid catalyzed TEOS silica aerogels  

Microsoft Academic Search

The experimental results on the influence of molar ratios of precursor, solvent and water on the physical properties of TEOS silica aerogels are reported. The aerogels have been prepared by hydrolysis and polycondensation of tetraethoxysilane (TEOS) using citric acid as a new catalyst followed by supercritical drying in an autoclave. In order to identify the optimal condition for producing the

P. B. Wagh; A. Venkateswara Rao; D. Haranath

1998-01-01

475

Experimental impacts into Teflon targets and LDEF thermal blankets  

NASA Astrophysics Data System (ADS)

The Long Duration Exposure Facility (LDEF) exposed approximately 20 sq m of identical thermal protective blankets, predominantly on the Ultra-Heavy Cosmic Ray Experiment (UHCRE). Approximately 700 penetration holes greater than 300 micron in diameter were individually documented, while thousands of smaller penetrations and craters occurred in these blankets. As a result of their 5.7 year exposure and because they pointed into a variety of different directions relative to the orbital motion of the nonspinning LDEF platform, these blankets can reveal important dynamic aspects of the hypervelocity particle environment in near-earth orbit. The blankets were composed of an outer teflon layer (approximately 125 micron thick), followed by a vapor-deposited rear mirror of silver (less than 1000 A thick) that was backed with an organic binder and a thermal protective paint (approximately 50 to 75 micron thick), resulting in a cumulative thickness (T) of approximately 175 to 200 microns for the entire blanket. Many penetrations resulted in highly variable delaminations of the teflon/metal or metal/organic binder interfaces that manifest themselves as 'dark' halos or rings, because of subsequent oxidation of the exposed silver mirror. The variety of these dark albedo features is bewildering, ranging from totally absent, to broad halos, to sharp single or multiple rings. Over the past year experiments were conducted over a wide range of velocities (i.e., 1 to 7 km/s) to address velocity dependent aspects of cratering and penetrations of teflon targets. In addition, experiments were performed with real LDEF thermal blankets to duplicate the LDEF delaminations and to investigate a possible relationship of initial impact conditions on the wide variety of dark halo and ring features.

Hoerz, F.; Cintala, M. J.; Zolensky, M. E.; Bernhard, R. P.; See, T. H.

1994-03-01

476

Helium-cooled test blanket module box behaviour under accidental pressurisation  

Microsoft Academic Search

The helium-cooled lithium–lead (HCLL) breeder blanket concept is one of the two breeder blanket lines presently developed by the EU for DEMO reactor. In the short-term so-called DEMO relevant test blanket modules (TBMs) of these breeder blanket concepts shall be designed, manufactured, tested, installed, commissioned and operated in ITER for first tests in a fusion environment.For the purpose of licensing

Christian Girard; Nicolas Schmidt; Jean-François Salavy; Gilles Rampal

2008-01-01

477

Nuclear characteristics of D-D fusion reactor blankets - Technical data  

Microsoft Academic Search

Technical data on the nuclear characteristics of D-D fusion reactor blankets are presented as a supplement to Nakashima and Ohta (1978). Topics considered include the internal spectral shifter and energy converter, effects of neutron source ratio, the molten salt blanket, and the B4C cooled blanket. Bench-mark calculations of (H-T)B, (H-T)MG\\/(H-T)B, and phi-MG\\/phi-M are reported for an example of D-D blankets.

H. Nakashima; M. Ohta; Y. Nakao

1978-01-01

478

A facile route for 3D aerogels from nanostructured 1D and 2D materials  

PubMed Central

Aerogels have numerous applications due to their high surface area and low densities. However, creating aerogels from a large variety of materials has remained an outstanding challenge. Here, we report a new methodology to enable aerogel production with a wide range of materials. The method is based on the assembly of anisotropic nano-objects (one-dimensional (1D) nanotubes, nanowires, or two-dimensional (2D) nanosheets) into a cross-linking network from their colloidal suspensions at the transition from the semi-dilute to the isotropic concentrated regime. The resultant aerogels have highly porous and ultrafine three-dimensional (3D) networks consisting of 1D (Ag, Si, MnO2, single-walled carbon nanotubes (SWNTs)) and 2D materials (MoS2, graphene, h-BN) with high surface areas, low densities, and high electrical conductivities. This method opens up a facile route for aerogel production with a wide variety of materials and tremendous opportunities for bio-scaffold, energy storage, thermoelectric, catalysis, and hydrogen storage applications.

Jung, Sung Mi; Jung, Hyun Young; Dresselhaus, Mildred S.; Jung, Yung Joon; Kong, Jing

2012-01-01

479

The application of carbon aerogel electrodes to desalination {ampersand} waste treatment  

SciTech Connect

An electrically-regenerated electrosorption process known as carbon aerogel capacitive deionization (CDI) has been developed by Lawrence Livermore National Laboratory (LLNL) for continuously removing ionic impurities from aqueous streams. A salt solution flows through an unobstructed channel formed by numerous pairs of parallel carbon aerogel electrodes. Each electrode has a very high Brunauer-Emmet-Teller (BET) surface area (2.0-5.4 x 1O{sup 6} ft{sup 2} lb{sup -1} or 400-1100) and very low electrical resistivity (< 40 m{omega} cm). Surface areas of 1.3 x 10{sup 7} ft{sup 2} lb{sup -1} (2600 m{sup 2} g{sup -1}) have been achieved activation. After polarization, anions and cations are removed from the electrolyte by the imposed electric field and electrosorbed onto the carbon aerogel. The solution is thus separated into two streams, concentrate and purified water. Based upon this analysis, it is concluded that carbon aerogel CDI may be an energy-efficient alternative to electrodialysis and reverse osmosis for the desalination of brackish water (< 5000 ppm), provided that cell geometries and aerogel properties are carefully tailored for such applications.

Farmer, J.C., Tran, T.D., Richardson, J.H., Fix, D.V., May, S.C., Thomson, S.L.

1997-08-01

480

A facile route for 3D aerogels from nanostructured 1D and 2D materials.  

PubMed

Aerogels have numerous applications due to their high surface area and low densities. However, creating aerogels from a large variety of materials has remained an outstanding challenge. Here, we report a new methodology to enable aerogel production with a wide range of materials. The method is based on the assembly of anisotropic nano-objects (one-dimensional (1D) nanotubes, nanowires, or two-dimensional (2D) nanosheets) into a cross-linking network from their colloidal suspensions at the transition from the semi-dilute to the isotropic concentrated regime. The resultant aerogels have highly porous and ultrafine three-dimensional (3D) networks consisting of 1D (Ag, Si, MnO(2), single-walled carbon nanotubes (SWNTs)) and 2D materials (MoS(2), graphene, h-BN) with high surface areas, low densities, and high electrical conductivities. This method opens up a facile route for aerogel production with a wide variety of materials and tremendous opportunities for bio-scaffold, energy storage, thermoelectric, catalysis, and hydrogen storage applications. PMID:23152940

Jung, Sung Mi; Jung, Hyun Young; Dresselhaus, Mildred S; Jung, Yung Joon; Kong, Jing

2012-11-14