WorldWideScience
 
 
1

MEMS Cantilevers - Sacrificial Layer Removal  

Science.gov (United States)

This animation, created by Southwest Center for Microsystems Education (SCME), "illustrates the removal or etch of the sacrificial layer of silicon dioxide. Removing this layer allows the micro-cantilevers to move. Such cantilevers are used as sensors for a variety of applications." The supporting MEMS Cantilever Learning Modules and activities can be downloaded from the SCME website under Educational Materials.

2014-07-22

2

Polyimide sacrificial layer and novel materials for post-processing surface micromachining  

Science.gov (United States)

We present a low-temperature post-processing module, utilizing polyimide as a sacrificial layer and novel materials such as PECVD SiC and metals (sputtered aluminium and titanium) as structural layers. The use of spin-on polyimide allows an all-dry final release step overcoming stiction problems often encountered in wet sacrificial etching processes. The spinning and curing procedure has been tailored to the specific needs of the IC-compatible post-process module. For the patterning of the polyimide, thin films of aluminium, PECVD silicon oxide or silicon carbide are employed as a mask layer. Anisotropic etching of the mask film and of the polyimide layer is accomplished by RIE. After patterning the structural layer, sacrificial etching of the polyimide is done using an isotropic dry etch process in high-density oxygen plasma. An underetch rate of 4 ?m min-1 is achieved. Compatibility with different structural materials is tested and test structures are designed and realized in a fully post-processing surface micromachining module.

Bagolini, A.; Pakula, L.; Scholtes, T. L. M.; Pham, H. T. M.; French, P. J.; Sarro, P. M.

2002-07-01

3

Laser forward transfer using a sacrificial layer: Influence of the material properties  

International Nuclear Information System (INIS)

The deposition of metal and polymer patterns was achieved with a laser forward transfer method involving a sacrificial release layer. Aluminum, gelatine and methylcellulose pixels were precisely transferred from a donor to a receiver substrate using the UV-laser decomposition of an intermediate triazene polymer layer. The roughness and edge sharpness of the pixels are found to be very dependent on the transfer material. For aluminum, a thick layer of triazene has to be used to get a clean transfer, which remains unclear yet. The applied fluence as well as the triazene thickness are strongly interdependent on the mechanical properties of the transfer layer. This work endeavours some important aspects of the transfer mechanism, and opens the way to further investigations, which are necessary to get a clear understanding of the process

4

Laser forward transfer using a sacrificial layer: Influence of the material properties  

Energy Technology Data Exchange (ETDEWEB)

The deposition of metal and polymer patterns was achieved with a laser forward transfer method involving a sacrificial release layer. Aluminum, gelatine and methylcellulose pixels were precisely transferred from a donor to a receiver substrate using the UV-laser decomposition of an intermediate triazene polymer layer. The roughness and edge sharpness of the pixels are found to be very dependent on the transfer material. For aluminum, a thick layer of triazene has to be used to get a clean transfer, which remains unclear yet. The applied fluence as well as the triazene thickness are strongly interdependent on the mechanical properties of the transfer layer. This work endeavours some important aspects of the transfer mechanism, and opens the way to further investigations, which are necessary to get a clear understanding of the process.

Fardel, Romain [Empa, Swiss Federal Laboratories for Materials Testing and Research, Laboratory for Functional Polymers, Uberlandstrasse 129, 8600 Duebendorf (Switzerland); Paul Scherrer Institut, General Energy Research Department, 5232 Villigen PSI (Switzerland)], E-mail: romain.fardel@empa.ch; Nagel, Matthias; Nueesch, Frank [Empa, Swiss Federal Laboratories for Materials Testing and Research, Laboratory for Functional Polymers, Uberlandstrasse 129, 8600 Duebendorf (Switzerland); Lippert, Thomas [Empa, Swiss Federal Laboratories for Materials Testing and Research, Laboratory for Functional Polymers, Uberlandstrasse 129, 8600 Duebendorf (Switzerland)], E-mail: thomas.lippert@psi.ch; Wokaun, Alexander [Paul Scherrer Institut, General Energy Research Department, 5232 Villigen PSI (Switzerland)

2007-12-15

5

SU-8 Based MEMS Process with Two Metal Layers using ?-Si as a Sacrificial Material  

Polymer based microelectromechanical systems (MEMS) micromachining is finding more interest in research and applications. This is due to its low cost and less time processing compared with silicon MEMS. SU-8 is a photo-patternable polymer that is used as a structural layer for MEMS and microfluidic devices. In addition to being processed with low cost, it is a biocompatible material with good mechanical properties. Also, amorphous silicon (?-Si) has found use as a sacrificial layer in silicon MEMS applications. ?-Si can be deposited at large thicknesses for MEMS applications and also can be released in a dry method using XeF2 which can solve stiction problems related to MEMS applications. In this thesis, an SU-8 MEMS process is developed using amorphous silicon (?-Si) as a sacrificial layer. Electrostatic actuation and sensing is used in many MEMS applications. SU-8 is a dielectric material which limits its direct use in electrostatic actuation. This thesis provides a MEMS process with two conductive metal electrodes that can be used for out-of-plane electrostatic applications like MEMS switches and variable capacitors. The process provides the fabrication of dimples that can be conductive or non-conductive to facilitate more flexibility for MEMS designers. This SU-8 process can fabricate SU-8 MEMS structures of a single layer of two different thicknesses. Process parameters were tuned for two sets of thicknesses which are thin (5-10?m) and thick (130?m). Chevron bent-beam structures and different suspended beams (cantilevers and bridges) were fabricated to characterize the SU-8 process through extracting the density, Young’s Modulus and the Coefficient of Thermal Expansion (CTE) of SU-8. Also, the process was tested and used as an educational tool through which different MEMS structures were fabricated including MEMS switches, variable capacitors and thermal actuators.

Ramadan, Khaled S.

2012-04-01

6

Sacrificial materials for SFR severe accident mitigation  

International Nuclear Information System (INIS)

In case of postulated Sodium Fast Reactor severe accidents, the core could melt and form a mixture called corium. In this event, sacrificial materials could then be used to reduce the heat load to the retention structure and to avoid the criticality risk. This approach was applied in the past with, for instance, depleted uranium oxide used as sacrificial material in the SNR300 ex-vessel core catcher. A review of sacrificial material candidates has been conducted, considering both neutron absorber and diluent materials. This review was initially based on criteria related to thermophysical and chemical thermodynamic properties (melting and boiling temperature, ability to form a liquid solution with molten fuel...). Neutronic calculations have been done for some generic configurations in order to estimate the reactivity decrease due to the mixing of corium with some different materials. Materials such as aluminium oxide, uranium oxide and hafnium or europium oxides will be presented in more details and their relative advantages discussed. (authors)

7

Parylene C as a Sacrificial Material for Microfabrication  

Science.gov (United States)

Parylene C has been investigated for use as a sacrificial material in microfabrication. Although Parylene C cannot be patterned lithographically like photoresists, it nevertheless extends the range of processing options by offering a set of properties that are suitable for microfabrication and are complementary to those of photoresists. The compatibility of Parylene C with several microfabrication processes was demonstrated in experiments in which a thin film of Parylene C was deposited on a silicon wafer, then several thin metal films were deposited and successfully patterned, utilizing the Parylene C pads as a sacrificial layer. The term "parylene" -- a contraction of "poly(para-xylene)" -- denotes a family of vapor-deposited polymers. In Parylene C (the most common form of parylene), a chlorine atom is substituted for one of the hydrogen atoms on the benzene ring of each para-xylene moiety. Heretofore, parylenes have been used as conformal coating materials in diverse applications.

Beamesderfer, Michael

2005-01-01

8

High dose, heavy ion implantation into metals: the use of sacrificial surface layers to enhance retention  

International Nuclear Information System (INIS)

While of considerable interest for the production of metallic alloys, high dose, heavy ion implantation is highly problematical, since the process is limited by sputtering effects. Sputtering is less significant, however, for light target materials, such as C and Al. This paper summarizes studies involving the use of light materials (such as C and Al) which act as slowly sputtering ''sacrificial layers'' when deposited on metallic targets prior to heavy ion implantation. The use of C and Al sacrificial coatings has enabled implanted ion retentions of 100% to be obtained in a number of ion-metal target systems, where the retentions in uncoated samples were as low as 20%. Ion implantation invariably leads to mixing at the sacrificial layer-metal target interface. This mixing may be detrimental in certain systems, so it is useful to be able to minimize or remove this mixed region. To achieve this, a number of techniques have been investigated: (1) removal of the mixed region in the latter stages of the implant; (2) using a barrier layer or chemical effects to minimize mixing at the sacrificial layer-metal interface; (3) choosing a sacrificial layer material which forms a mixed region which has desirable properties. The results of these investigations, for a number of different ion-target systems, are outlined in this paper. (orig.)

9

Performance characterization of geopolymer composites for hot sodium exposed sacrificial layer in fast breeder reactors  

Energy Technology Data Exchange (ETDEWEB)

Highlights: • Performance evaluation of geopolymers subjected to hot liquid sodium is performed. • Apart from mechanical properties, micro-analytical techniques are used for material characterization. • The geopolymer composite showed comparatively lesser damage than conventional cement composites. • Geopolymer technology can emerge as a new choice for sacrificial layer in SCFBRs. - Abstract: A sacrificial layer of concrete is used in sodium cooled fast breeder reactors (SCFBRs) to mitigate thermo-chemical effect of accidentally spilled sodium at and above 550 °C on structural concrete. Performance of this layer is governed by thermo-chemical stability of the ingredients of sacrificial layer concrete. Concrete with limestone aggregate is generally used as a sacrificial layer. Conventional cement based systems exhibit instability in hot liquid sodium environment. Geo-polymer composites are well known to perform excellently at elevated temperatures compared to conventional cement systems. This paper discusses performance of such composites subjected to exposure of hot liquid sodium in air. The investigation includes comprehensive evaluation of various geo-polymer composites before any exposure, after heating to 550 °C in air, and after immersing in hot liquid sodium initially heated to 550 °C in air. Results from the current study indicate that hot liquid sodium produces less damage to geopolymer composites than to the existing conventional cement based system. Hence, the geopolymer technology has potential application in mitigating the degrading effects of sodium fires and can emerge as a new choice for sodium exposed sacrificial layer in SCFBRs.

Haneefa, K. Mohammed, E-mail: mhkolakkadan@gmail.com [Department of Civil Engineering, IIT Madras, Chennai (India); Santhanam, Manu [Department of Civil Engineering, IIT Madras, Chennai (India); Parida, F.C. [Radiological Safety Division, Indira Gandhi Centre for Atomic Research, Kalpakkam (India)

2013-12-15

10

Performance characterization of geopolymer composites for hot sodium exposed sacrificial layer in fast breeder reactors  

International Nuclear Information System (INIS)

Highlights: • Performance evaluation of geopolymers subjected to hot liquid sodium is performed. • Apart from mechanical properties, micro-analytical techniques are used for material characterization. • The geopolymer composite showed comparatively lesser damage than conventional cement composites. • Geopolymer technology can emerge as a new choice for sacrificial layer in SCFBRs. - Abstract: A sacrificial layer of concrete is used in sodium cooled fast breeder reactors (SCFBRs) to mitigate thermo-chemical effect of accidentally spilled sodium at and above 550 °C on structural concrete. Performance of this layer is governed by thermo-chemical stability of the ingredients of sacrificial layer concrete. Concrete with limestone aggregate is generally used as a sacrificial layer. Conventional cement based systems exhibit instability in hot liquid sodium environment. Geo-polymer composites are well known to perform excellently at elevated temperatures compared to conventional cement systems. This paper discusses performance of such composites subjected to exposure of hot liquid sodium in air. The investigation includes comprehensive evaluation of various geo-polymer composites before any exposure, after heating to 550 °C in air, and after immersing in hot liquid sodium initially heated to 550 °C in air. Results from the current study indicate that hot liquid sodium produces less damage to geopolymer composites than to the existing conventional cement based system. Hence, the geopolymer technology has potential application in mitigating the degrading effects of sodium fires and can emerge as a new choice for sodium exposed sacrificial layer in SCFBRs

11

Cleaning graphene with a titanium sacrificial layer  

International Nuclear Information System (INIS)

Graphene is a promising material for future electronic applications and chemical vapor deposition of graphene on copper is a promising method for synthesizing graphene on the wafer scale. The processing of such graphene films into electronic devices introduces a variety of contaminants which can be difficult to remove. An approach to cleaning residues from the graphene channel is presented in which a thin layer of titanium is deposited via thermal e-beam evaporation and immediately removed. This procedure does not damage the graphene as evidenced by Raman spectroscopy, greatly enhances the electrical performance of the fabricated graphene field effect transistors, and completely removes the chemical residues from the surface of the graphene channel as evidenced by x-ray photoelectron spectroscopy.

12

Cleaning graphene with a titanium sacrificial layer  

Energy Technology Data Exchange (ETDEWEB)

Graphene is a promising material for future electronic applications and chemical vapor deposition of graphene on copper is a promising method for synthesizing graphene on the wafer scale. The processing of such graphene films into electronic devices introduces a variety of contaminants which can be difficult to remove. An approach to cleaning residues from the graphene channel is presented in which a thin layer of titanium is deposited via thermal e-beam evaporation and immediately removed. This procedure does not damage the graphene as evidenced by Raman spectroscopy, greatly enhances the electrical performance of the fabricated graphene field effect transistors, and completely removes the chemical residues from the surface of the graphene channel as evidenced by x-ray photoelectron spectroscopy.

Joiner, C. A., E-mail: cjoiner3@gatech.edu; Roy, T.; Hesabi, Z. R.; Vogel, E. M. [School of Materials Science and Engineering, Georgia Institute of Technology, Atlanta, Georgia 30332 (United States); Chakrabarti, B. [School of Materials Science and Engineering, Georgia Institute of Technology, Atlanta, Georgia 30332 (United States); Department of Materials Science and Engineering, The University of Texas at Dallas, Richardson, Texas 75080 (United States)

2014-06-02

13

Thin polymer films as sacrificial layers for easier cleaning  

Digital Repository Infrastructure Vision for European Research (DRIVER)

We propose a new approach for the removal of fouling agents from an interface. The interface is pre-coated with a polymer layer of a few nanometers thick that can be removed by a simple trigger such as a change in pH or salt concentration. When fouling agents adsorb on the interface, they can be removed by simply desorbing (sacrificing) the polymer coating. We show a proof of principle of this concept on the basis of two different types of sacrificial layers. The first system consists of a si...

Vos, W. M.; Keizer, A.; Cohen Stuart, M. A.; Kleijn, J. M.

2010-01-01

14

Shadowgraphy investigation of laser-induced forward transfer: Front side and back side ablation of the triazene polymer sacrificial layer  

International Nuclear Information System (INIS)

Thin films of a photodecomposible triazene polymer are used as sacrificial layer for the micro-deposition of sensitive materials by laser-induced forward transfer. To understand the ablation process of this sacrificial layer, the ultraviolet laser ablation of triazene films was investigated by time-resolved shadowgraphy. Irradiation from the film side shows a complete decomposition into gaseous fragments, while ablation through the substrate causes ejection of a solid flyer of polymer. The occurence of the flyer depends on the film thickness as well as on the applied fluence, and a compact flyer is obtaind when these two parameters are optimized

15

Debris bed and sacrificial materials interactions at high temperatures  

International Nuclear Information System (INIS)

A series of high temperature furnace experiments were conducted to examine materials interactions under possible post-accident heat removal conditions following a hypothetical core disruptive accident. The study of material interaction within simulated dried-out debris beds and between such debris beds and candidate core retention materials produced results with significant reactor safety implications. Urania sintering dependence on particle size was examined because sintering may determine characteristics of the crust between molten fuel and structural or sacrificial material. The behavior of a mixed UO2/steel simulated debris bed was studied above the steel melting point. Finally the interaction of a particulate UO2 bed with Harklase (98% MgO) brick was examined at various temperatures to determine the characteristics to be expected

16

Method of using sacrificial materials for fabricating internal cavities in laminated dielectric structures  

Science.gov (United States)

A method of using sacrificial materials for fabricating internal cavities and channels in laminated dielectric structures, which can be used as dielectric substrates and package mounts for microelectronic and microfluidic devices. A sacrificial mandrel is placed in-between two or more sheets of a deformable dielectric material (e.g., unfired LTCC glass/ceramic dielectric), wherein the sacrificial mandrel is not inserted into a cutout made in any of the sheets. The stack of sheets is laminated together, which deforms the sheet or sheets around the sacrificial mandrel. After lamination, the mandrel is removed, (e.g., during LTCC burnout), thereby creating a hollow internal cavity in the monolithic ceramic structure.

Peterson, Kenneth A. (Albuquerque, NM)

2009-02-24

17

Improvement in semiconductor laser printing using a sacrificial protecting layer for organic thin-film transistors fabrication  

International Nuclear Information System (INIS)

Laser-induced forward transfer (LIFT) has been used to deposit pixels of an organic semiconductor, distyryl-quaterthiophenes (DS4T). The dynamics of the process have been investigated by shadowgraphic imaging for the nanosecond (ns) and picosecond (ps) regime on a time-scale from the laser iradiation to 1.5 ?s. The morphology of the deposit has been studied for different conditions. Intermediate sacrificial layer of gold or triazene polymer has been used to trap the incident radiation. Its role is to protect the layer to be transferred from direct irradiation and to provide a mechanical impulse strong enough to eject the material.

18

Improvement in semiconductor laser printing using a sacrificial protecting layer for organic thin-film transistors fabrication  

Science.gov (United States)

Laser-induced forward transfer (LIFT) has been used to deposit pixels of an organic semiconductor, distyryl-quaterthiophenes (DS4T). The dynamics of the process have been investigated by shadowgraphic imaging for the nanosecond (ns) and picosecond (ps) regime on a time-scale from the laser iradiation to 1.5 ?s. The morphology of the deposit has been studied for different conditions. Intermediate sacrificial layer of gold or triazene polymer has been used to trap the incident radiation. Its role is to protect the layer to be transferred from direct irradiation and to provide a mechanical impulse strong enough to eject the material.

Rapp, Ludovic; Cibert, Christophe; Nénon, Sébastien; Alloncle, Anne Patricia; Nagel, Matthias; Lippert, Thomas; Videlot-Ackermann, Christine; Fages, Frédéric; Delaporte, Philippe

2011-04-01

19

Development of an SU-8 MEMS process with two metal electrodes using amorphous silicon as a sacrificial material  

Science.gov (United States)

This work presents an SU-8 surface micromachining process using amorphous silicon as a sacrificial material, which also incorporates two metal layers for electrical excitation. SU-8 is a photo-patternable polymer that is used as a structural layer for MEMS and microfluidic applications due to its mechanical properties, biocompatibility and low cost. Amorphous silicon is used as a sacrificial layer in MEMS applications because it can be deposited in large thicknesses, and can be released in a dry method using XeF2, which alleviates release-based stiction problems related to MEMS applications. In this work, an SU-8 MEMS process was developed using ?-Si as a sacrificial layer. Two conductive metal electrodes were integrated in this process to allow out-of-plane electrostatic actuation for applications like MEMS switches and variable capacitors. In order to facilitate more flexibility for MEMS designers, the process can fabricate dimples that can be conductive or nonconductive. Additionally, this SU-8 process can fabricate SU-8 MEMS structures of a single layer of two different thicknesses. Process parameters were optimized for two sets of thicknesses: thin (5-10 µm) and thick (130 µm). The process was tested fabricating MEMS switches, capacitors and thermal actuators.

Ramadan, Khaled S.; Nasr, Tarek; Foulds, Ian G.

2013-03-01

20

Porous silicon oxide sacrificial layers deposited by pulsed-direct current magnetron sputtering for microelectromechanical systems  

International Nuclear Information System (INIS)

The development of silicon oxide layers with high etch rates to be used as sacrificial layers in surface micromachining for microsystems fabrication poses a great technological challenge. In this work, we have investigated the possibility of obtaining easily removable silicon oxide layers by pulsed-direct current (DC) magnetron reactive sputtering. We have carried out a comprehensive study of the influence of the deposition parameters (total pressure and gas composition) on the composition, residual stress and lateral etch rate in fluoride wet solutions of the films. This study has allowed to determine the sputtering conditions to deposit, at high rates (up to 0.1 ?m/min), silicon oxide films with excellent characteristics for their use as sacrificial layers. Films with roughness around 5 nm rms, residual stress below 100 MPa and very high lateral etch rate (up to 5 ?m/min), around 70 times higher than for thermal silicon oxide, have been achieved. The structural characteristics of these easily removable silicon oxide layers have been assessed by infrared spectroscopy and atomic force microscopy, which have revealed that the films exhibit a porous structure, related to very specific sputter conditions. Finally, the viability of these films has been demonstrated by using them as sacrificial layer in the fabrication process of AlN-based microresonators.

 
 
 
 
21

Homeotropic Alignment of a Discotic Liquid Crystal Induced by a Sacrificial Layer  

DEFF Research Database (Denmark)

A convenient method to induce face-on orientation of an alkoxy phtalocyanine discotic mesogen is described. The alignment is imposed by the confinement of the discotic thin films with a top sacrificial polymer layer that is easily removed by washing with a selective solvent, after thermal annealing. Thin films have been characterized by optical and atomic force microscopy, UV-Vis absorption spectroscopy, and grazing incidence wide angle X-ray scattering. The data converge in showing the central role of the sacrificial layer in promoting alignment with the planar molecules orienting parallel to the substrate in an essentially homeotropic arrangement over large lateral length scales and the persistence of this desirable alignment after removal of the layer.

Pouzet, Eric; De Cupere, Vinciane

2009-01-01

22

Fabrication of LTCC Micro-fluidic Devices Using Sacrificial Carbon Layers  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Ease of fabrication and design flexibility are two attractive features of low temperature co-fired ceramics (LTCC) technology for fabrication of complex micro-fluidic devices. Such structures are designed and processed using different shaping methods, the extent and complexity of which depends on the final device specifications (dimensions, mechanical and functional properties). In this work, we propose a sacrificial layer method based on carbon-black paste, which burns out during the L...

Birol, Hansu; Maeder, Thomas; Jacq, Caroline; Corradini, Giancarlo; Passerini, Reynald; Fournier, Yannick; Stra?ssler, Sigfrid; Ryser, Peter

2005-01-01

23

Soft substrate as a sacrificial layer for fabrication free-standing SU-8-based nanofluidic system  

Science.gov (United States)

In this paper, we describe a new fabrication process utilizing polydimethylesiloxane (PDMS) and polyester (PET) as a sacrificial substrate for fabricating free-standing SU-8-based nanofluidic system. The soft substrate permits SU-8 UV cured patterning and layer-to-layer bonding, and allows the SU-8 structures to be easily peeled off from the substrate after complete fabrication. In the process, PDMS-on glass is used as a handling wafer, on which SU-8 based trenches is imprinted by a flexible film mold using low-pressure nanoimprint lithography. The reservoir pattern of SU-8 is fabricated on the bonding layer, in which PET serves as substrate. The nanochannel is sealed by optimized bonding process, which is flexible and easily controllable with the use of soft substrate as a sacrificial layer. After bonding process, PDMS and PET could be easily peeled off from nanaofluidic system. The SEM results shows that the height of the fully enclosed nanochannels will be about hundreds nanometer. Large area of free standing SU-8 structure layers are successfully fabricated and peeled off from the soft substrate layer as single continuous sheets.

Li, Xiaojun; Wang, Xudi; Jin, Jian; Li, Xin; Tian, Yangchao; Fu, Shaojun

2010-10-01

24

Fabrication of a subminiature silicon condenser microphone using the sacrificial layer technique  

Digital Repository Infrastructure Vision for European Research (DRIVER)

The application of the sacrificial layer technique for the fabrication of a subminiature silicon condenser microphone with a plasma-enhanced chemical vapor deposited silicon nitride diaphragm has been investigated. Square diaphragms with dimensions from 0.6 to 2.6 mm and a thickness of 1 ¿m have been realized. Measurements on a microphone with a 2×2 mm diaphragm and a 1 ¿m airgap have shown that a sensitivity of 1.4 mV/Pa for low frequencies can be achieved with a low bias voltage (-2 V). ...

Scheeper, P. R.; Olthuis, W.; Bergveld, P.

1991-01-01

25

Generation of cavities in silicon wafers by laser ablation using silicon nitride as sacrificial layer  

International Nuclear Information System (INIS)

Throughout this investigation, experiments on laser ablation with silicon (Si) wafers have been performed using silicon nitride (Si3N4) as a sacrificial layer to find the optimal fluence capable of removing the Si3N4, which allows the subsequent anisotropic etching in Si with potassium hydroxide. As a result, an alternative to the traditional micromachining techniques that require more steps and processing times has been introduced. The effect of the pulse numbers on Si wafers has been studied and it has been observed that when increasing the pulse numbers at the same fluence, the capacity of the pyramidal cavity formed was greater than using only one pulse at higher fluences. Microcavities were performed with a floating Si3N4 layer. This happens to be very useful for the development of drug delivery systems and the manufacture of microarrays. Microcavities were also used as masters for the fabrication of microionizers in polydimethyl siloxane (PDMS).

26

Development of Sacrificial Material for the Eu-APR1400 Core Catcher  

Energy Technology Data Exchange (ETDEWEB)

To increase and diversify the export marker of the Korean nuclear reactor design, we developed the Eu- APR1400 reactor design based on the APR1400 reactor design, satisfying the European nuclear design requirements including the European Utility Requirements (EUR) and the Finnish requirements of YVL. As recommended by both requirements, the so called core-catcher molten core ex-vessel cooling facility was developed to manage a severe accident at the Eu-APR1400 reactor involving a core meltdown and to mitigate its consequences. Usually, sacrificial material (SM), which controls the melt properties and modifies melt conditions favorable to corium retention, can be employed to protect the core catcher body from the molten core and increase its cooling capability. The EPR reactor design (by Areva, France) core catcher consists of the initial corium retention space, the transportation channel and the wide spreading room for core melt cooling. The EPR used two kinds of SM to protect the initial core retention space from core melt and to spread the core melt across the wide spreading room using the different compositions. The VVER (Russia) ensures melt localization in a water-cooled vessel located directly beneath the reactor. SM is used to remove the thermal focusing effect by the layer inversion process between metallic and oxidic melts. The functional requirements for the SM determined for the present core catcher are (1) melting spreading improvement, (2) focusing effect prevention, (3) hydrogen explosion prevention, (4) FP (fission product) release decreasing, and (5) melt recriticality exclusion. The rest of the paper is organized as follows. The next section provides detailed descriptions of the composition of the present SM, which satisfies its functional requirements. Following this, the manufacturing process of the SM is presented

Suh, Jung Soo; Kim, Mun Soo; Kim, Yong Soo [KHNP Central Research Institute, Daejeon (Korea, Republic of)

2011-10-15

27

Development of Sacrificial Material for the Eu-APR1400 Core Catcher  

International Nuclear Information System (INIS)

To increase and diversify the export marker of the Korean nuclear reactor design, we developed the Eu- APR1400 reactor design based on the APR1400 reactor design, satisfying the European nuclear design requirements including the European Utility Requirements (EUR) and the Finnish requirements of YVL. As recommended by both requirements, the so called core-catcher molten core ex-vessel cooling facility was developed to manage a severe accident at the Eu-APR1400 reactor involving a core meltdown and to mitigate its consequences. Usually, sacrificial material (SM), which controls the melt properties and modifies melt conditions favorable to corium retention, can be employed to protect the core catcher body from the molten core and increase its cooling capability. The EPR reactor design (by Areva, France) core catcher consists of the initial corium retention space, the transportation channel and the wide spreading room for core melt cooling. The EPR used two kinds of SM to protect the initial core retention space from core melt and to spread the core melt across the wide spreading room using the different compositions. The VVER (Russia) ensures melt localization in a water-cooled vessel located directly beneath the reactor. SM is used to remove the thermal focusing effect by the layer inversion process between metallic and oxidic melts. The functional requirements for the SM determined for the present core catcher are (1) melting spreading improvement, (2) focusing effectspreading improvement, (2) focusing effect prevention, (3) hydrogen explosion prevention, (4) FP (fission product) release decreasing, and (5) melt recriticality exclusion. The rest of the paper is organized as follows. The next section provides detailed descriptions of the composition of the present SM, which satisfies its functional requirements. Following this, the manufacturing process of the SM is presented

28

Comparative study of LPE and VPE silicon thin film on porous sacrificial layer  

International Nuclear Information System (INIS)

Thin film single crystal silicon on foreign substrate is an attractive way to realize cheap and efficient photovoltaic devices. In this paper we will compare epitaxial growth of silicon thin film on double porous sacrificial layers obtained by liquid or vapor phase epitaxy (LPE or VPE). Porous silicon is formed by electrochemical anodisation of monocrystalline silicon in a HF/ethanol solution. VPE is achieved in an atmospheric pressure chemical vapor deposition (APCVD) reactor under H2 atmosphere. Growth rate is in between 0.5-3 ?m/min. LPE is realised in a graphite sliding boat using indium or tin as solvent. Growth rate is in the range 0.1-1 ?m/min depending on the temperature, the cooling rate and the solvent. We discuss the substrate orientation, temperature, growth rate, layer homogeneity and electrical properties of the epilayers for both growing techniques. Diffusion length and mobility are measured respectively with LBIC and Hall effect technique. The values obtained for p-type (?>100 V/cm2/s and Ln>100 ?m) allows the realisation of solar cell using interdigitated technology on the top of this layer, which is detached and transferred onto mullite substrate

29

Selective Removal of Dry-Etching Residue Derived from Polymer Sacrificial Layer for Microelectromechanical-System Device Fabrication  

Science.gov (United States)

A selective removal of dry-etching residue using hydrofluoric acid (HF) vapor is described in relation to the fabrication of microelectromechanical-system (MEMS) devices. Auger electron spectroscopy (AES) analysis of residue after dry etching of polymer sacrificial layers reveals that the residue is mainly composed of silicon oxides. HF vapor removes the dry-etching residue, and raising the vapor temperature enables the selective removal of the residue without damaging silicon dioxide (SiO2), which is often used as the insulator for MEMS devices. Direct-contact-type MEMS switches with SiO2 insulators fabricated using polymer sacrificial layers demonstrate the effectiveness of removing the dry-etching residue selectively.

Takagahara, Kazuhiko; Kuwabara, Kei; Sakata, Tomomi; Ishii, Hiromu; Sato, Yasuhiro; Jin, Yoshito

2012-09-01

30

Fabrication of low-temperature co-fired ceramics micro-fluidic devices using sacrificial carbon layers  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Ease of fabrication and design flexibility are two attractive features of low temperature co-fired ceramics (LTCC) technology for fabrication of complex micro-fluidic devices. Such structures are designed and processed using different shaping methods, the extent and complexity of which depends on the final device specifications (dimensions, mechanical and functional properties). In this work, we propose a sacrificial layer method based on carbon-black paste, which burns out during the LTCC fi...

Birol, Hansu; Maeder, Thomas; Jacq, Caroline; Straessler, Sigfrid; Ryser, Peter

2005-01-01

31

Further work on sodium borates as sacrificial materials for a core-catcher  

International Nuclear Information System (INIS)

Sodium borates are suitable low melting point sacrificial materials for a core-catcher of a fast reactor. Concept, design and initial development work have been described previously. Here we report on the measurements of density, volumetric thermal expansion coefficients and viscosity of borax and sodium metaborate, pure and with various percentages of dissolved UO2. The density of these molten salts was measured with the buoyancy method in the temperature range 850 - 13000C, while the viscosity was measured in the temperature range 700 - 12500C with a Haake viscosity balance. Simulation experiments with low melting point materials were performed to investigate the ratio of the downward to sideward melt velocity. The results of these experiments show that this ratio is equal to 0.34 for a solid to liquid density ratio rho = 1.66. For the real borax core-catcher rho = 4 and this would correspond to a velocity ratio of about one

32

Creation of freestanding wrinkled nano-films with desired deformation properties by controlling the surface morphology of a sacrificial layer  

Science.gov (United States)

Various wrinkle patterns can be formed due to the buckling of a stiff thin film on a compliant substrate. However, most wrinkled films previously reported were fixed on a large deformable substrate and thereby the potential deformability of the film was mechanically constrained by the substrate. In this study, we developed a technique for forming various wrinkled structures on the surface of a sacrificial resin layer. Since the sacrificial layer can be subsequently removed with a solvent, freestanding wrinkled films are created using the sacrificial layer. We found that a wrinkled structure is formed on the surface of the layer by applying a compressive strain to the resin layer at the appropriate moment during the hardening process. The wrinkle pattern depends on the curing time and the timing of the straining in two in-plane orthogonal directions. In addition to conventional stripe and labyrinth patterns by simple uniaxial and equi-biaxial strains, respectively, it was found that independent biaxial strains induce interesting structures, such as an orthogonally ordered wrinkle pattern and a nonsymmetrical buckling structure, in which the stripe array produced by the first straining remains and many finer wrinkles appear in each stripe by the second straining in the orthogonal direction. We conducted tensile experiments for 300-nm-thick freestanding Cu films having these wrinkled structures. The wrinkled nano-films have a variety of mechanical properties: the stripe structure has extremely high deformability (more than 10% strain) and reversibility, the labyrinth structure shows planar isotropic deformation, and the nonsymmetrical buckling structure has an anisotropic modulus and strength. Finite element analysis on the wrinkle structures revealed that the local stress concentration dominates the fracture limits.

Hirakata, Hiroyuki; Maruyama, Tomohiro; Yonezu, Akio; Minoshima, Kohji

2013-05-01

33

Amor Sacrificial  

Directory of Open Access Journals (Sweden)

Full Text Available El sacrificio corresponde al amor argumentado. Su ejercicio muchas veces inscrito en el orden sagrado de la cultura no deja de comprometer la participación de la Bemächtigungstrieb", pulsión de apoderamiento. En tanto el sacrificio se rinde al otro para su apaciguamiento o complacencia, por supuesto amor a él, se descubre un desprendimiento de goce, al elevar el mal, la destrucción, al estatuto de soberano bien. La demanda sacrificial atribuida a los dioses introduce la dimensión de falta en estos seres supuestamente omnipotentes. Amor y dioses requieren de su provisión persistente de sacrificios. El cuerpo sometido a la tiranía de la imagen idealizada y exaltada es expuesto a distintos y renovados sacrificios. Y parece que ningún sacrificio fuera satisfactorio. La proclama de guerra puede inscribir de forma preponderante la retórica del sacrificio en su pretensión heroica o de sujeción abominable.

Mario Orozco Guzm\\u00E1n

2011-01-01

34

Sugar-mediated disassembly of mucin/lectin multilayers and their use as pH-Tolerant, on-demand sacrificial layers.  

Science.gov (United States)

The layer-by-layer (LbL) assembly of thin films on surfaces has proven to be an extremely useful technology for uses ranging from optics to biomedical applications. Releasing these films from the substrate to generate so-called free-standing multilayer films opens a new set of applications. Current approaches to generating such materials are limited because they can be cytotoxic, difficult to scale up, or have undesirable side reactions on the material. In this work, a new sacrificial thin film system capable of chemically triggered dissolution at physiological pH of 7.4 is described. The film was created through LbL assembly of bovine submaxillary mucin (BSM) and the lectin jacalin (JAC) for a (BSM/JAC) multilayer system, which remains stable over a wide pH range (pH 3-9) and at high ionic strength (up to 5 M NaCl). This stability allows for subsequent LbL assembly of additional films in a variety of conditions, which could be released from the substrate by incubation in the presence of a competitive inhibitor sugar, melibiose, which selectively disassembles the (BSM/JAC) section of the film. This novel multilayer system was then applied to generate free-standing, 7 ?m diameter, circular ultrathin films, which can be attached to a cell surface as a "backpack". A critical thickness of about 100 nm for the (BSM/JAC) film was required to release the backpacks from the glass substrate, after incubation in melibiose solution at 37 °C for 1 h. Upon their release, backpacks were subsequently attached to murine monocytes without cytotoxicity, thereby demonstrating the compatibility of this mucin-based release system with living cells. PMID:24964165

Polak, Roberta; Crouzier, Thomas; Lim, Rosanna M; Ribbeck, Katharina; Beppu, Marisa M; Pitombo, Ronaldo N M; Cohen, Robert E; Rubner, Michael F

2014-08-11

35

SU-8 surface micromachining using polydimethylglutarimide (pmgi) as a sacrificial material  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Microelecromechanical systems (MEMS) are mechanical structures that are fabricated using similar techniques used to fabricate integrated circuits. MEMS were originally fabricated using silicon based technologies; however, a more diverse set of materials, including polymers, are being now being used to fabricate MEMS. Polymer micromachining is less expensive than silicon micromachining and can be performed in less time. SU-8 is finding greater use as a structural polymer MEMS material due to i...

Foulds, Ian G.

2007-01-01

36

Pt/Ti Electrodes of PZT Thin Films Patterning by Novel Lift-Off Using ZnO as a Sacrificial Layer  

International Nuclear Information System (INIS)

We achieve a successful novel lift-off of patterning Pt/Ti electrodes on SiO2/Si substrates by employing ZnO sacrificial layer deposition and patterning, successive uniform Pt/Ti deposition and final lift-off. Then we deposit PZT thin films on the electrodes. Compared with the conventional lift-off processes for the electrodes, this novel process does not need post-annealing, which must be performed after conventional lift-off process. It is demonstrated that the electrodes patterned by the novel lift-off process have stronger adhesion. The electrodes and the PZT films on the electrodes are more compact and smoother than those by the conventional lift-off process

37

Manufacture of micro-electro-mechanical-system using sacrificial layer made of silicon, useful for micro-electro-mechanical-system device architecture, e.g. radio-frequency capacitive switch and current switch  

Digital Repository Infrastructure Vision for European Research (DRIVER)

NOVELTY - A micro-electro-mechanical-system (MEMS) is manufactured by the use of a sacrificial layer that is made of silicon. USE - The invention is used in surface micromachining for the manufacture of a MEMS containing a suspended metal layer or MEMS device architecture. MEMS device is a suspended gate metal oxide semiconductor field effect transistor (SG-MOSFET). It is used as radio-frequency capacitive switch, current switch, radio-frequency tuneable capacitor, magnetic field sensor, acce...

Ionescu, M. A.; Fluckiger, Ph; Hibert, C.; Fritschi, R.; Pott, V.

2002-01-01

38

Hot sodium-triggered thermo-chemical degradation of concrete aggregates in the sodium resistant sacrificial layers of fast breeder reactors  

Energy Technology Data Exchange (ETDEWEB)

Highlights: • Concrete aggregates were exposed to liquid sodium exposure at 550 °C. • Thermal and chemical effects were studied using megascopic and micro-analytical techniques. • Aggregates underwent significant thermo-chemical degradation upon exposure. • Limestone found more suitable for sodium environment than siliceous aggregate. - Abstract: Sodium is used as an efficient coolant in fast breeder reactor (FBR) for extracting nuclear heat from its high power density core to steam generator, to produce electricity. Accidentally spilled Sodium at elevated temperatures of 550 °C or above may interact with concrete leading to its deterioration. A sacrificial concrete layer is provided on the structural concrete to mitigate the harmful impacts of these interactions. Locally available crushed rocks like limestone and granite are employed as aggregates in sacrificial and structural concrete respectively. Rocks are naturally occurring multi-mineral and multiphase inorganic systems of the earth. Aggregates are the main constituents of concrete accounting for 70–80% of its mass. In this paper, an attempt is made to study the physico-chemical modifications that may occur in the aggregates during the interactions between liquid sodium and the aggregates of concrete. The experimental strategy consists of heating of granite, limestone and river sand aggregates at 550 °C for 30 min and further treating them with 1 Normal aqueous solution of NaOH, to differentiate thermal and chemical effects. Furthermore, sodium-aggregate interaction study at 550 °C was conducted to characterize the combined effects of heat and sodium. Siliceous aggregates (granite and river sand) were found to be easily attacked by ferric oxidation during heating in air and also subjected to rapid chemical reactions with liquid NaOH, producing mineral phases of sodium silicate, sodium orthosilicates, calcium orthosilicates and sodium carbonates. Initiation and propagation of cracking in the siliceous aggregates are sustained due to differential thermal expansion of minerals and chemical invasion of inter-granular structures. Limestone, on the other hand, was mostly stable, and its thermal performance was affected by the fraction of deleterious accessory minerals present in it. Combined action of corrosive NaOH and heat induced cracks in hot sodium environment at 550 °C may lead to more drastic degradation of concrete with siliceous aggregate than with limestone aggregate.

Haneefa, K. Mohammed, E-mail: mhkolakkadan@gmail.com [Department of Civil Engineering, IIT Madras, Chennai (India); Santhanam, Manu [Department of Civil Engineering, IIT Madras, Chennai (India); Ramasamy, R. [Department of Ocean Engineering, IIT Madras, Chennai (India); Parida, F.C. [Radiological Safety Division, Indira Gandhi Centre for Atomic Research, Kalpakkam (India)

2013-12-15

39

Hot sodium-triggered thermo-chemical degradation of concrete aggregates in the sodium resistant sacrificial layers of fast breeder reactors  

International Nuclear Information System (INIS)

Highlights: • Concrete aggregates were exposed to liquid sodium exposure at 550 °C. • Thermal and chemical effects were studied using megascopic and micro-analytical techniques. • Aggregates underwent significant thermo-chemical degradation upon exposure. • Limestone found more suitable for sodium environment than siliceous aggregate. - Abstract: Sodium is used as an efficient coolant in fast breeder reactor (FBR) for extracting nuclear heat from its high power density core to steam generator, to produce electricity. Accidentally spilled Sodium at elevated temperatures of 550 °C or above may interact with concrete leading to its deterioration. A sacrificial concrete layer is provided on the structural concrete to mitigate the harmful impacts of these interactions. Locally available crushed rocks like limestone and granite are employed as aggregates in sacrificial and structural concrete respectively. Rocks are naturally occurring multi-mineral and multiphase inorganic systems of the earth. Aggregates are the main constituents of concrete accounting for 70–80% of its mass. In this paper, an attempt is made to study the physico-chemical modifications that may occur in the aggregates during the interactions between liquid sodium and the aggregates of concrete. The experimental strategy consists of heating of granite, limestone and river sand aggregates at 550 °C for 30 min and further treating them with 1 Normal aqueous solution of NaOH, to differentiate thermal and chemical effects. Furthermore, sodium-aggregate interaction study at 550 °C was conducted to characterize the combined effects of heat and sodium. Siliceous aggregates (granite and river sand) were found to be easily attacked by ferric oxidation during heating in air and also subjected to rapid chemical reactions with liquid NaOH, producing mineral phases of sodium silicate, sodium orthosilicates, calcium orthosilicates and sodium carbonates. Initiation and propagation of cracking in the siliceous aggregates are sustained due to differential thermal expansion of minerals and chemical invasion of inter-granular structures. Limestone, on the other hand, was mostly stable, and its thermal performance was affected by the fraction of deleterious accessory minerals present in it. Combined action of corrosive NaOH and heat induced cracks in hot sodium environment at 550 °C may lead to more drastic degradation of concrete with siliceous aggregate than with limestone aggregate

40

Surface imprinting on nano-TiO{sub 2} as sacrificial material for the preparation of hollow chlorogenic acid imprinted polymer and its recognition behavior  

Energy Technology Data Exchange (ETDEWEB)

Highlights: Black-Right-Pointing-Pointer Used surface imprinting technique with nano-TiO{sub 2} as sacrificial support material. Black-Right-Pointing-Pointer Improved adsorption capability of the H-MIP1 compared with the previous work. Black-Right-Pointing-Pointer Excellent mass transfer dynamics for the H-MIP1. Black-Right-Pointing-Pointer Investigated adsorption thermodynamic of the H-MIP1. - Abstract: Surface imprinting chlorogenic acid (CGA) on nano-TiO{sub 2} particles as sacrificial support material was successfully performed by using 4-vinylpyridine (4-VP) as functional monomer to obtain a hollow CGA-imprinted polymer (H-MIP1). Fourier transmission infrared spectrometry (FTIR) and scanning electron microscopy (SEM) were utilized for structurally characterizing the polymers obtained and adsorption dynamics and thermodynamic behavior investigated according to different models. Binding selectivity, adsorption capacity and the reusability for this H-MIP1 were also evaluated. This hollow CGA imprinted polymer shows rapid binding dynamics and higher binding capability toward the template molecules. The pseudo first-order kinetic model was shown best to describe the binding process of CGA on the H-MIP1 and Langmuir isotherm model best to fit the experimental adsorption isotherm data. Through adsorption isotherms at different temperatures, thermodynamic parameter values were obtained. Selectivity coefficients for the H-MIP1 toward the template were 2.209, 3.213, 1.746 and 2.353 relative to CA, VA, PCA and GA, respectively. This H-MIP1 was also indicated with a good imprint effect and a high capability to capture CGA from methanol extract of Eucommia ulmoides (E. ulmoides) leaves. Additionally, a good reusability for this imprinted polymer was exhibited during repeated adsorption-desorption use.

Li Hui, E-mail: lihuijsdx@163.com [College of Chemistry and Chemical Engineering, Jishou University, Hunan 416000, Jishou (China); Key Laboratory of Plant Resource Conservation and Utilization, Jishou University, Hunan 416000, Jishou (China); Li Gui [Key Laboratory of Plant Resource Conservation and Utilization, Jishou University, Hunan 416000, Jishou (China); Li Zhiping; Lu Cuimei; Li Yanan [College of Chemistry and Chemical Engineering, Jishou University, Hunan 416000, Jishou (China); Tan Xianzhou [Key Laboratory of Plant Resource Conservation and Utilization, Jishou University, Hunan 416000, Jishou (China)

2013-01-01

 
 
 
 
41

Building biomedical materials layer-by-layer  

Directory of Open Access Journals (Sweden)

Full Text Available In this materials perspective, the promise of water based layer-by-layer (LbL assembly as a means of generating drug-releasing surfaces for biomedical applications, from small molecule therapeutics to biologic drugs and nucleic acids, is examined. Specific advantages of the use of LbL assembly versus traditional polymeric blend encapsulation are discussed. Examples are provided to present potential new directions. Translational opportunities are discussed to examine the impact and potential for true biomedical translation using rapid assembly methods, and applications are discussed with high need and medical return.

Paula T. Hammond

2012-05-01

42

CMUTs with high-K atomic layer deposition dielectric material insulation layer.  

Science.gov (United States)

Use of high-? dielectric, atomic layer deposition (ALD) materials as an insulation layer material for capacitive micromachined ultrasonic transducers (CMUTs) is investigated. The effect of insulation layer material and thickness on CMUT performance is evaluated using a simple parallel plate model. The model shows that both high dielectric constant and the electrical breakdown strength are important for the dielectric material, and significant performance improvement can be achieved, especially as the vacuum gap thickness is reduced. In particular, ALD hafnium oxide (HfO2) is evaluated and used as an improvement over plasma-enhanced chemical vapor deposition (PECVD) silicon nitride (Six)Ny)) for CMUTs fabricated by a low-temperature, complementary metal oxide semiconductor transistor-compatible, sacrificial release method. Relevant properties of ALD HfO2) such as dielectric constant and breakdown strength are characterized to further guide CMUT design. Experiments are performed on parallel fabricated test CMUTs with 50-nm gap and 16.5-MHz center frequency to measure and compare pressure output and receive sensitivity for 200-nm PECVD Six)Ny) and 100-nm HfO2) insulation layers. Results for this particular design show a 6-dB improvement in receiver output with the collapse voltage reduced by one-half; while in transmit mode, half the input voltage is needed to achieve the same maximum output pressure. PMID:25474786

Xu, Toby; Tekes, Coskun; Degertekin, F

2014-12-01

43

Surface imprinting on nano-TiO2 as sacrificial material for the preparation of hollow chlorogenic acid imprinted polymer and its recognition behavior  

Science.gov (United States)

Surface imprinting chlorogenic acid (CGA) on nano-TiO2 particles as sacrificial support material was successfully performed by using 4-vinylpyridine (4-VP) as functional monomer to obtain a hollow CGA-imprinted polymer (H-MIP1). Fourier transmission infrared spectrometry (FTIR) and scanning electron microscopy (SEM) were utilized for structurally characterizing the polymers obtained and adsorption dynamics and thermodynamic behavior investigated according to different models. Binding selectivity, adsorption capacity and the reusability for this H-MIP1 were also evaluated. This hollow CGA imprinted polymer shows rapid binding dynamics and higher binding capability toward the template molecules. The pseudo first-order kinetic model was shown best to describe the binding process of CGA on the H-MIP1 and Langmuir isotherm model best to fit the experimental adsorption isotherm data. Through adsorption isotherms at different temperatures, thermodynamic parameter values were obtained. Selectivity coefficients for the H-MIP1 toward the template were 2.209, 3.213, 1.746 and 2.353 relative to CA, VA, PCA and GA, respectively. This H-MIP1 was also indicated with a good imprint effect and a high capability to capture CGA from methanol extract of Eucommia ulmoides (E. ulmoides) leaves. Additionally, a good reusability for this imprinted polymer was exhibited during repeated adsorption-desorption use.

Li, Hui; Li, Gui; Li, Zhiping; Lu, Cuimei; Li, Yanan; Tan, Xianzhou

2013-01-01

44

Treatment of colloidal waste material by electroflotation using sacrificial electrodes. Gisei denkyoku wo mochiita denkai fujo bunri ni yoru colloid jo kendaku busshitsu no shori  

Energy Technology Data Exchange (ETDEWEB)

Experiments were carried out on batch electroflotation using aluminum sacrificial electrodes for such a colloidal waste material as disperse dye. The experiments were intended to elucidate separation mechanisms and look into various conditions to maximize separation rate. The following results were obtained: Aluminum dissolution is proportional to current density and is larger than the theoretical value based on Faraday's law; the separation process consists of two steps; in the first step the sol concentration remained nearly at the initial value, and flocculation of the sol is based on a charge neutralization with dissolved aluminum ions; the second step is a flotation and separation process in which the separation followed a linear velocity expression and the velocity constant increased with increasing current densities; the aluminum dissolution can be increased effectively with use of a polarity conversion method to switch anodic and cathodic polarities every certain times, where the optimum conversion time was found to be about 900 seconds; and use of bipolar electrodes disposed with auxiliary electrodes was effective to optimize the operation voltage and reduce the size of flotation tanks. 11 refs., 14 figs.

Osasa, K.; Nakakura, H.; Tanaka, H. (Yamaguchi Univ., Yamaguchi (Japan). Faculty of Engineering)

1993-03-10

45

CMP Control of Multi-Layer Inter-Layer Dielectrics (ILD) using X-ray Reflectivity  

International Nuclear Information System (INIS)

Thin sacrificial films are used as cap layer in the back-end semiconductor processing for protecting the bulk porous inter-layer low-k dielectric during the CMP process. The existing optical measurement techniques struggle to separate these thin films from the bulk low-k due to very similar optical coefficients. Glancing angle x-ray reflectivity is well suited for separation of thin sacrificial film and bulk dielectric film as x-ray reflectivity depends strongly on changes in electron densities for two materials. This paper discusses the x-ray reflectivity technique and its applications for measurement of low-k stack and sacrificial oxide post CMP

46

Nanoscale buckling deformation in layered copolymer materials  

Digital Repository Infrastructure Vision for European Research (DRIVER)

In layered materials, a common mode of deformation involves buckling of the layers under tensile deformation in the direction perpendicular to the layers. The instability mechanism, which operates in elastic materials from geological to nanometer scales, involves the elastic contrast between different layers. In a regular stacking of "hard" and "soft" layers, the tensile stress is first accommodated by a large deformation of the soft layers. The inhibited Poisson contraction...

Makke, Ali; Perez, Michel; Lame, Olivier; Barrat, Jean-louis

2012-01-01

47

Application of the GEMINI2 code to Develop the Sacrificial Concrete for the Core-catcher Experiment by KAERI  

Energy Technology Data Exchange (ETDEWEB)

In the late phase of a severe accident, the reactor lower vessel may fail, the hot molten corium discharging into the reactor cavity can threaten the integrity of the containment due to the combustible gas generation, the fission product release and the large amount of steam generation from the MCCI (molten core concrete interaction). Therefore, it is important to make the relocated hot molten corium cool-down in a safe and fast manner. For this purpose, KAERI has proposed a new cooling concept for the corium in a cavity by simultaneously injecting water and non-condensable gas into the nozzles embedded in the concrete basement from the bottom. From the COMET experimental results, the most important condition to achieve a cooling for a melt by a 'bottom injection' will be whether the melt can be changed into a porous structure or not. It means that the phenomena for forming a porous structure by a fuel coolant interaction during a bottom injection are the crucial mechanisms that need to be identified. The possible scenario to form a porous layer may be a 'local pressure build-up' by a strong steam generation. This pressure build-up may propagate and expand in a lateral direction. Also, this steam filled void region may iterate an expansion and shrinkage. In addition, this strong vibration and steaming may produce a porous layer. KAERI is planning to perform a core-catcher experiment for identifying the debris coolability by a bottom injection. To fulfill this experiment successfully, it is necessary to develop sacrificial concrete. The sacrificial concrete can decrease not only the corium temperature but also the viscosity. An enhanced mobility can provide a higher possibility to form a porous layer. The purpose of this study is to elucidate the CaO content in the sacrificial concrete using the GEMINI2 code. Figure 1 is the conceptual picture for the core-catcher experiment. The melt from the termite reactions will be relocated over the sacrificial concrete. The water will be injected from the bottom after the melt has eroded the sacrificial concrete. The purpose of the experiment is to estimate whether a porous layer can be formed or not. The main ingredient of the sacrificial concrete is CaO. The application of the sacrificial concrete can decrease not only the solidus temperature but also the viscosity. If the molten corium has a high solidification temperature, then even a small cooling at the begin of the bottom injection may make the most of the molten material freeze immediately. A lower viscosity can provide more mobility to a molten material. An enhanced mobility and a lowered solidification temperature can provide an enhanced possibility of forming a porous layer. Consequently, the purpose of this study is to elucidate the CaO content for the sacrificial concrete, which can make the solidus and liquidus temperature low using the GEMINI-2 code. This sacrificial concrete will be applied to a test for estimating the corium coolability under a bottom injection based on the new cooling concept developed by KAERI.

Park, Jong Hwa; Kim, Jong Hwan; Min, Byung Tae; Kim, Hwan Yeol; Hong, Seong Wan [Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of)

2009-05-15

48

Surface micromachined PDMS microfluidic devices fabricated using a sacrificial photoresist  

International Nuclear Information System (INIS)

PDMS is a widely used material for construction of microfluidic devices. The traditional PDMS microfabrication process, although versatile, cannot be used to form microfluidic devices with embedded tall topological features, such as thick-film electrodes and porous reactor beds. This paper presents an elegant surface micromachining process for microfluidic devices that allows complete leak-proof sealing and a conformal contact of the PDMS with tall pre-existing topographical features and demonstrates this approach by embedding 6 µm thick Ag/AgCl (high capacity 1680 µA s) electrodes inside the microchannels. In this process, thin spin-cast films of the PDMS are used as the structural material and a photoresist is used as the sacrificial material. A crucial parameter, namely adhesion of the spun-cast structural layer to the substrate, was characterized for different pre-polymer ratios using a standard tensile test, and a 1:3 (curing agent:base) combination was found to be the best with a maximum adhesion strength of 7.2 MPa. The elastic property of the PDMS allowed extremely fast release times of ?1 min of the fabricated microchannels. The versatility of this process was demonstrated by the fabrication of a pneumatic microvalve with multi-layered microchannel geometry. The valve closure occurred at 6.37 kPa

49

Cucurbit[8]uril-based stimuli-responsive films as a sacrificial layer for preparation of free-standing thin films.  

Science.gov (United States)

A pseudo-polycation was prepared based on the supramolecular cucurbit[8]uril ternary complex. It was then layer-by-layer assembled with poly(acrylic acid) to fabricate a stimuli-responsive film, which exhibited disassembly properties in response to stimuli, providing a supramolecular route for the fabrication of free-standing thin films. PMID:25370182

Li, Dan-Dan; Chen, Xia-Chao; Ren, Ke-Feng; Ji, Jian

2015-01-15

50

Reflection and transmission for layered composite materials  

Science.gov (United States)

A layered planar structure consisting of different bianisotropic materials separated by jump-immittance sheets is considered. Reflection and transmission coefficients are determined via a chain-matrix algorithm. Applications are important for radomes and radar-absorbing materials.

Graglia, Roberto D.; Uslenghi, Piergiorgio L. E.

1991-01-01

51

Novel process for direct bonding of GaN onto glass substrates using sacrificial ZnO template layers to chemically lift-off GaN from c-sapphire  

Science.gov (United States)

GaN was grown on ZnO-buffered c-sapphire (c-Al2O3) substrates by Metal Organic Vapor Phase Epitaxy. The ZnO then served as a sacrificial release layer, allowing chemical lift-off of the GaN from the c-Al2O3 substrate via selective wet etching of the ZnO. The GaN was subsequently direct-wafer-bonded onto a glass substrate. X-Ray Diffraction, Scanning Electron Microscopy, Energy Dispersive X-ray microanalysis, Room Temperature Photoluminescence & optical microscopy confirmed bonding of several mm2 of crack-free wurtzite GaN films onto a soda lime glass microscope slide with no obvious deterioration of the GaN morphology. Using such an approach, InGaN based devices can be lifted-off expensive single crystal substrates and bonded onto supports with a better cost-performance profile. Moreover, the approach offers the possibility of reclaiming and reusing the substrate.

Rogers, D. J.; Ougazzaden, A.; Sandana, V. E.; Moudakir, T.; Ahaitouf, A.; Teherani, F. Hosseini; Gautier, S.; Goubert, L.; Davidson, I. A.; Prior, K. A.; McClintock, R. P.; Bove, P.; Drouhin, H.-J.; Razeghi, M.

2012-02-01

52

Studies towards freestanding GaN in hydride vapor phase epitaxy by in-situ etching of a sacrificial ZnO buffer layer  

Energy Technology Data Exchange (ETDEWEB)

By in-situ etching of a ZnO buffer layer freestanding GaN layers were prepared by hydride vapor phase epitaxy (HVPE). For the template growth, single crystalline ZnO buffer layers, grown by pulsed laser deposition on sapphire, were used. They were overgrown with a thin GaN layer by a multilayer growth using metal organic vapor phase epitaxy (MOVPE). The removal of the ZnO buffer during the HVPE growth allowed the fabrication of strain-free freestanding GaNlayers with a full width-half-maximum of the donor bound exciton (D{sup 0}X) of 2.3 meV at a position of 3.47 eV in low temperature (15 K) photoluminescence (copyright 2009 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

Lipskil, Frank; Thapa, Sarad B.; Hertkorn, Joachim; Wunderer, Thomas; Schwaiger, Stephan; Scholz, Ferdinand [Institute of Optoelectronics, Ulm University, 89081 Ulm (Germany); Feneberg, Martin; Wiedenmann, Michael; Thonke, Klaus [Institute of Semiconductor Physics, Ulm University, 89081 Ulm (Germany); Hochmuth, Holger; Lorenz, Michael; Grundmann, Marius [Semiconductor Physics Group, Institute for Experimental Physics II, University Leipzig, 04103 Leipzig (Germany)

2009-06-15

53

LTCC free-standing structures with mineral sacrificial paste  

Digital Repository Infrastructure Vision for European Research (DRIVER)

In this work, mineral sacrificial pastes (MSP) previously developed for standard thick-film technology (alumina substrates) are extended to LTCC in order to make a capacitive anemometer. Application of MSP materials on free-sintering (unconstrained and not zero-shrinkage) LTCC is challenging: shrinkage must be matched to that of the LTCC in order to avoid excessive deformation, or sufficiently compliant materials must be used. Here, different MSP materials / materials systems are...

Fournier, Yannick; Triverio, Olivier; Maeder, Thomas; Ryser, Peter

2008-01-01

54

KAPOOL experiments to simulate molten corium - sacrificial concrete interaction  

International Nuclear Information System (INIS)

In future Light Water Reactors special devices (core catchers) might be required to prevent containment failure by basement erosion after reactor pressure vessel melt-through during a core meltdown accident. In the planned European Pressurized Reactor (EPR) the core melt is retained in the reactor cavity for ? 1 h to pick up late melts after the failure of the reactor pressure vessel. The reactor cavity is protected by a layer of sacrificial concrete and closed by a melt gate at the bottom towards the spreading compartment. After erosion of the sacrificial concrete and melt-through of the gate the core melt should be distributed homogeneously into the spreading compartment. There the melt is cooled by flooding with water. The knowledge of the sacrificial concrete erosion phase in the reactor cavity is essential for the severe accident assessment. Several KAPOOL experiments have been performed to investigate the erosion of two possible compositions of sacrificial concretes using alumina-iron thermite melts as a simulant for the core melt. Erosion rates as a function of the melt temperature and the inhomogeneity of the melt front are presented in this paper. (authors)

55

Sacrificial wafer bonding for planarization after very deep etching  

Digital Repository Infrastructure Vision for European Research (DRIVER)

A new technique is presented that provides planarization after a very deep etching step in silicon. This offers the possibility for resist spinning and layer patterning as well as realization of bridges or cantilevers across deep holes or grooves. The sacrificial wafer bonding technique contains a wafer bond step followed by an etch back. Results of polymer bonding followed by dry etching and anodic bonding combined with KOH etching are discussed. The polymer bonding has been applied in a str...

Spiering, Vincent L.; Berenschot, J. W.; Elwenspoek, Miko; Fluitman, Jan H. J.

1995-01-01

56

Ultrasonic classification of thin layers within multi-layered materials  

International Nuclear Information System (INIS)

Methods for non-destructive inspection of layered materials are becoming more and more popular as a way of assuring product integrity and quality. In this paper, we present a model-based technique using ultrasonic measurements for classification of thin bonding layers within three-layered materials. This could be, for example, an adhesive bond between two thin plates, where the integrity of the bonding layer needs to be evaluated. The method is based on a model of the wave propagation of pulse-echo ultrasound that first reduces the measured data to a few parameters for each measured point. The model parameters are then fed into a statistical classifier that assigns the bonding layer to one of a set of predefined classes. In this paper, two glass plates are bonded together with construction silicone, and the classifiers are trained to determine if the bonding layer is intact or if it contains regions of air or water. Two different classification methods are evaluated: nominal logistic regression and discriminant analysis. The former is slightly more computationally demanding but, as the results show, it performs better when the model parameters cannot be assumed to belong to a multivariate Gaussian distribution. The performance of the classifiers is evaluated using both simulations and real measurements

57

Innovative design and material solutions of thermal contact layers for high heat flux applications in fusion devices  

International Nuclear Information System (INIS)

One difficulty associated with the design and development of sacrificial plasma facing components that have to handle the high heat and particle fluxes in ITER is achieving the necessary contact conductance between the plasma protection material and the high-conductivity substrate in contact with the coolant. This paper presents a novel bond idea which is proposed as one of the options for the sacrificial energy dump targets located at the bottom of the divertor legs. The bonded joint in this design concept provides thermal and electrical contact between the armour and the cooled sub-structure while promoting remote, in-situ maintenance repair and an easy replaceability of the armour part without disturbing the cooling pipes or rewelding neutron irradiated materials. To provide reliable and demountable adhesion, the bond consists of a metal alloy, treated in the semi-solid phase so that it leads to a fine dispersion of a globular solid phase into a liquid matrix (rheocast process). This thermal bond layer would normally operate in the solid state but could be brought reversibly to the semi-solid state during the armour replacement simply by heating it slightly above its solidus temperature. Material and design options are discussed in this paper. Possible methods of installation and removal are described, and lifetime considerations are addressed. In order to validate this concept within the ITER time-frame, a R ampersand D programme must be rapidly implementedogramme must be rapidly implemented

58

Inkjet printing of 2D layered materials.  

Science.gov (United States)

Inkjet printing of 2D layered materials, such as graphene and MoS2, has attracted great interests for emerging electronics. However, incompatible rheology, low concentration, severe aggregation and toxicity of solvents constitute critical challenges which hamper the manufacturing efficiency and product quality. Here, we introduce a simple and general technology concept (distillation-assisted solvent exchange) to efficiently overcome these challenges. By implementing the concept, we have demonstrated excellent jetting performance, ideal printing patterns and a variety of promising applications for inkjet printing of 2D layered materials. PMID:25169938

Li, Jiantong; Lemme, Max C; Östling, Mikael

2014-11-10

59

Layer coefficients for NHDOT pavement materials  

Science.gov (United States)

In 1992, the New Hampshire Department of Transportation (NHDOT) experimented with the use of reclaimed asphalt concrete as a base course material, identified by NHDOT as reclaimed stabilized base (RSB). The RSB and a control test section were placed on Interstate 93 between exits 18 and 19. The RSB test section was designed to the same structural number (SN) as the control. To evaluate the structural capacity of these test sections, the U.S. Army Cold Regions Research and Engineering Laboratory (CRREL) conducted deflection tests using a Dynatest 8000 falling weight deflectometer (FWD). Preliminary analysis of the results by NHDOT personnel showed higher deflection in the reclaimed asphalt concrete test sections. The explanation was that the layer coefficient used for the RSB layer in the design was probably incorrect. A total of 10 test sections constituting the base course materials used by NHDOT were built near Bow, New Hampshire. CRREL evaluated and estimated the layer coefficients of the base course materials. The test program was developed to characterize the material in more than one way. Tests were conducted with the heavy weight deflectometer (HWD), dynamic cone penetrometer (DCP) and the Clegg hammer. In situ California bearing ratio (CBR) tests were also conducted. The deflection from the HWD were used with the WESDEF back calculation program to determine the layer moduli. The moduli were than used with the AASHTO Design Guide to calculate the layer coefficients. The layer coefficients were also determined with the method proposed by Rohde. The CBR values from the Clegg hammer, in situ CBR and DCP tests were also used in the relationships in the HDM model to determine the layer coefficients.

Janoo, Vincent C.

1994-09-01

60

Acoustic cloaking using layered pentamode materials.  

Science.gov (United States)

While receiving less attention in the literature than electromagnetic cloaking, theoretical efforts to define and create acoustic cloaks based upon mimicking coordinate transformations through use of metamaterials is of interest. The present work extends recent analysis of Norris [Proc. R. Soc. London, Ser. A 464, 2411-2434 (2008)] by considering a range of cloaks, from those comprised of fluid layers which are isotropic in bulk moduli with anisotropic density to those having anisotropic bulk moduli and isotropic density. In all but pure inertial varieties, fluid layers comprising the cloaks are pentamode materials governed by a special scalar acoustic equation for pseudopressure derived by Norris. In most cases presented, material properties of the fluid/pentamode layers are based upon target values specified by continuously varying properties resulting from theoretical coordinate transformations geared to minimize scattered pressure limited by realistic goals. The present work analyzes such cloaks for the specific case of plane wave scattering from an acoustically hard sphere. An initial exploration of the parameter space defining such cloaks (for example, material properties of its constituent layers, and operating frequency) is undertaken with a view toward "optimal" design. PMID:21117736

Scandrett, Clyde L; Boisvert, Jeffrey E; Howarth, Thomas R

2010-05-01

 
 
 
 
61

Electrochemistry : SacrificialAnode (10 Variations)  

Science.gov (United States)

The following electrochemical data may be helpful in answering the question below. One method for protecting metals against corrosion is to connect the metal directly to a "sacrificial anode". This is the method used to protect pipelines and ships hulls. Which of the following metals would you consider the best candidate for a sacrificial anode for a ship's hull? The hull is steel (which is mostly iron).

62

Protective nitrided layers for thermonuclear reactor materials  

International Nuclear Information System (INIS)

Radiation resistance and hydrogen permeability of nitrided layer of steel 08Kh18N10T-perspective material for the first wall of thermonuclear reactor-have been investigated. The nitrided layer was produced in the flow of high-purity nitrogen at 1000 deg C for 80 min, 8h 10 min and 22 h; diffusion zones 50, 150 and 200 ?m wide respectively were obtained. It is established, that irradiation with helium and hydrogen ions at 400-450 deg C by the doses up to 5x1019 cm-1 practically does not change the sample surface. The zone of internal nitridation, containing fine dispersed particles of Cr2N, decreases noticeally the steel hydrogen permeability

63

Ceramic nanostructure materials, membranes and composite layers  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Synthesis methods to obtain nanoscale materials will be briefly discussed with a focus on sol-gel methods. Three types of nanoscale composites (powders, membranes and ion implanted layers) will be discussed and exemplified with recent original research results. Ceramic membranes with a thickness of 1–10 ?m consist of a packing of elementary particles with a size of 3–7 nm. The mean pore size is about 2.5–3 nm. The preparation routes are based on sol and sol-gel technologies. The pores ...

Burggraaf, A. J.; Keizer, K.; Hassel, B. A.

1989-01-01

64

Sacrificial Plastic Mold With Electroplatable Base  

Science.gov (United States)

A sacrificial plastic mold having an electroplatable backing is provided. One embodiment consists of the infusion of a softened or molten thermoplastic through a porous metal substrate (sheet, screen, mesh or foam) and into the features of a micro-scale molding tool contacting the porous metal substrate. Upon demolding, the porous metal substrate will be embedded within the thermoplastic and will project a plastic structure with features determined by the mold tool. This plastic structure, in turn, provides a sacrificial plastic mold mechanically bonded to the porous metal substrate which provides a conducting support suitable for electroplating either contiguous or non-contiguous metal replicates. After electroplating and lapping, the sacrificial plastic can be dissolved to leave the desired metal structure bonded to the porous metal substrate. Optionally, the electroplated structures may be debonded from the porous substrate by selective dissolution of the porous substrate or a coating thereon.

Domeier, Linda A. (Danville, CA); Hruby, Jill M. (Livermore, CA); Morales, Alfredo M. (Livermore, CA)

2005-08-16

65

Redox buffered hydrofluoric acid etchant for the reduction of galvanic attack during release etching of MEMS devices having noble material films  

Science.gov (United States)

Etchant solutions comprising a redox buffer can be used during the release etch step to reduce damage to the structural layers of a MEMS device that has noble material films. A preferred redox buffer comprises a soluble thiophosphoric acid, ester, or salt that maintains the electrochemical potential of the etchant solution at a level that prevents oxidation of the structural material. Therefore, the redox buffer preferentially oxidizes in place of the structural material. The sacrificial redox buffer thereby protects the exposed structural layers while permitting the dissolution of sacrificial oxide layers during the release etch.

Hankins, Matthew G. (Albuquerque, NM)

2009-10-06

66

The density and distribution of sacrificial bonds in polymer chains determines the amount of dissipated energy  

International Nuclear Information System (INIS)

Full text: A common strategy for natural materials to increase their toughness while retaining a considerable stiffness is the use of sacrificial bonds (SBs). This study investigates the influence of the density and arrangement of SBs on the mechanical properties, especially the amount of dissipated energy of a single polymer chain using Monte Carlo simulation methods. The results show that: first, molecular chain fluctuations reduce the efficacy of sacrificial bonds. Second, increasing SB density increases the amount of dissipated energy per loading cycle. Third, a regular spatial arrangement of SBs is highly desirable for efficient energy dissipation. (author)

67

Electromagnetic cloaking by layered structure of homogeneous isotropic materials  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Electromagnetic invisibility cloak requires material with anisotropic distribution of the constitutive parameters deduced from a geometrical transformation as first proposed by Pendry et al. [Science 312, 1780 (2006)]. In this paper, we proposed a useful method to realize the required radius-dependent, anisotropic material parameters and to construct an electromagnetic cloak through concentric layered structure of thin, alternating layers of homogeneous isotropic materials. ...

Huang, Ying; Feng, Yijun; Jian, Tian

2007-01-01

68

Alternating Current Corrosion of Aluminium Sacrificial Anodes  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Direct Electric Heating (DEH) is applied to subsea oil production and transmission pipelines to prevent freezing of hydrates as wax during productions shut downs. To prevent clogging, the pipes are heated by application of alternating current (AC) voltage. As a result, a risk for AC corrosion is introduced, which is the motivation and subject of this thesis. The steel pipes are coated and applied conventional cathodic protection (CP) by use of AlZnIn sacrificial anodes. The present work focus...

Forthun, Kari

2013-01-01

69

A templated electrosynthesis of macroporous NiAl layered double hydroxides thin films.  

Science.gov (United States)

Colloidal crystals of polystyrene (PS) beads self-assembled on Pt electrode were used as a sacrificial template to electrosynthesis thin films of macroporous Layered Double Hydroxides (LDH). Such nanostructured materials display a high internal surface area and porosity leading to enhanced electrochemical performance. PMID:21125133

Prevot, Vanessa; Forano, Claude; Khenifi, Aicha; Ballarin, Barbara; Scavetta, Erika; Mousty, Christine

2011-02-14

70

Atomic layer deposition of nanostructured materials  

CERN Document Server

Atomic layer deposition, formerly called atomic layer epitaxy, was developed in the 1970s to meet the needs of producing high-quality, large-area fl at displays with perfect structure and process controllability. Nowadays, creating nanomaterials and producing nanostructures with structural perfection is an important goal for many applications in nanotechnology. As ALD is one of the important techniques which offers good control over the surface structures created, it is more and more in the focus of scientists. The book is structured in such a way to fi t both the need of the expert reader (du

Pinna, Nicola

2012-01-01

71

Novel solutions for thin film layer deposition for organic materials  

Science.gov (United States)

Innovative systems for carrier-gas enhanced vapor phase deposition of organic layers offer advanced methods for the precise deposition of complex thin-film layer stacks. The approach inherently avoids potential short-comings from solvent-based polymer deposition and offers new opportunities. The process operates at low pressure (thus avoiding complex vacuum setups), and, by employing AIXTRON's extensive experience in freely scalable solutions, can be adapted to virtually any production process and allows for R&D and production systems alike. Deposition of organic layers and stacks recommends the approach for a wide range of organic small molecule and polymer materials (including layers with gradual change of the composition), for conductive layers, for dielectric layers, for barrier systems, for OLED materials, and surface treatments such as oleophobic / hydrophobic coatings. With the combination of other vapor phase deposition solutions, hybrid systems combining organic and inorganic materials and other advanced stacks can be realized.

Keiper, Dietmar; Long, Michael; Schwambera, Markus; Gersdorff, Markus; Kreis, Juergen; Heuken, Michael

2011-03-01

72

Examples of material solutions in bimetallic layered castings  

Digital Repository Infrastructure Vision for European Research (DRIVER)

In paper is presented technology of bimetallic layered castings based on founding method of layer coating directly in cast process so-called method of mould cavity preparation. Prepared castings consist two fundamental parts i.e. bearing part and working part (layer). The bearing part of bimetallic layered casting is typical foundry material i.e. pearlitic grey cast iron, whereas working part (layer) is depending on accepted variant plates of alloy steels sort X6Cr13, X12Cr13, X10CrNi18-8 and...

Tenerowicz, S.; Cholewa, M.; Wro?bela, T.

2011-01-01

73

Novel composite materials synthesized by the high-temperature interaction of pyrrole with layered oxide matrices  

Science.gov (United States)

The initial goal of the research presented herein was to develop the very first synthetic metal---high-temperature superconductor ceramic composite material, in the specific form of a polypyrrole---Bi2Sr2CaCu 2O8+delta nanocomposite. In the course of scientific investigation, this scope was broadened to encompass structurally and compositionally similar layered bismuthates and simpler layered oxides. The latter substrates were prepared through novel experimental procedures that enhanced the chance of yielding nanostructured morphologies. The designed novel synthesis approaches yielded a harvest of interesting results that may be further developed upon their dissemination in the scientific community. High-temperature interaction of pyrrole with molybdenum trioxide substrates with different crystalline phases and morphologies led to the formation of the first members of a new class of heterogeneous microcomposites characterized by incomplete occupancy by the metal oxide core of the volume encapsulated by the rigid, amorphous permeable polymeric membrane that reproduces the volume of the initial grain of precursor substrate. The method may be applied for various heterogeneous catalyst substrates for the precise determination of the catalytically active crystallographic planes. In a different project, room-temperature, templateless impregnation of molybdenum trioxide substrates with different crystalline phases and morphologies by a large excess of silver (I) cations led to the formation of 1-D nanostructured novel Ag-Mo-O ternary phase in what may be the simplest experimental procedure available to date that has yielded a 1-D nanostructure, regardless the nature of the constituent material. Interaction of this novel ternary phase with pyrrole vapors at high reaction temperatures led to heterogeneous nanostructured composites that exhibited a silver nanorod core. Nanoscrolls of vanadium pentoxide xerogel were synthesized through a novel, facile reflux-based method that employed very acidic pH levels and long reaction times. The nanoscrolls proved to be an excellent precursor for the synthesis of reduced vanadium oxide nanosheets by the redox intercalation of long chain monoamine molecules. In a related development, the very first synthetic metal---mixed-valence polyoxovanadate salt hybrid material was synthesized in the form of a polypyrrole---tetrammonium hexavanadate microcomposite by a redox simultaneous co-precipitation in an aqueous solution. The novel material displayed good mechanical properties towards solid lubricant applications and tunable electronic conductivity. Nanocomposites of polypyrrole---layered bismuthates were produced by the topotactic intercalation of pyrrole and its subsequent in situ polymerization. Insulating and superconducting layered bismuthates were used in a similar experimental procedure that used pre-intercalated iodine species as sacrificial topotactic oxidizing agents. A novel method of iodine intercalation by a solution-based transport procedure was used in the process. Interaction of pyrrole with layered bismuthates at high reaction temperatures led to the formation of polymer-covered metal nanorods as a result of intrinsic lattice templating effect. The successful synthesis of the 1-D heterogeneous nanostructures represents the first example in which nanocomposites were used as precursors. Appropriate doping of the initial layered ceramic substrates led to polymer-covered metal alloy nanorods.

Pavel, Alexandru Cezar

74

Method for depositing layers of high quality semiconductor material  

Energy Technology Data Exchange (ETDEWEB)

Plasma deposition of substantially amorphous semiconductor materials is carried out under a set of deposition parameters which are selected so that the process operates near the amorphous/microcrystalline threshold. This threshold varies as a function of the thickness of the depositing semiconductor layer; and, deposition parameters, such as diluent gas concentrations, must be adjusted as a function of layer thickness. Also, this threshold varies as a function of the composition of the depositing layer, and in those instances where the layer composition is profiled throughout its thickness, deposition parameters must be adjusted accordingly so as to maintain the amorphous/microcrystalline threshold.

Guha, Subhendu (Troy, MI); Yang, Chi C. (Troy, MI)

2001-08-14

75

Epitaxial Growth of GaN-based LEDs on Simple Sacrificial Substrates  

Energy Technology Data Exchange (ETDEWEB)

The objective of this project is to produce alternative substrate technologies for GaN-based LEDs by developing an ALD interlayer of Al{sub 2}O{sub 3} on sacrificial substrates such as ZnO and Si. A sacrificial substrate is used for device growth that can easily be removed using a wet chemical etchant leaving only the thin GaN epi-layer. After substrate removal, the GaN LED chip can then be mounted in several different ways to a metal heat sink/reflector and light extraction techniques can then be applied to the chip and compared for performance. Success in this work will lead to high efficiency LED devices with a simple low cost fabrication method and high product yield as stated by DOE goals for its solid state lighting portfolio.

Ian Ferguson; Chris Summers

2009-12-31

76

Examples of material solutions in bimetallic layered castings  

Directory of Open Access Journals (Sweden)

Full Text Available In paper is presented technology of bimetallic layered castings based on founding method of layer coating directly in cast process so-called method of mould cavity preparation. Prepared castings consist two fundamental parts i.e. bearing part and working part (layer. The bearing part of bimetallic layered casting is typical foundry material i.e. pearlitic grey cast iron, whereas working part (layer is depending on accepted variant plates of alloy steels sort X6Cr13, X12Cr13, X10CrNi18-8 and X2CrNiMoN22-5-3. The ratio of thickness between bearing and working part is 8:1. The verification of the bimetallic layered castings was evaluated on the basis of ultrasonic NDT (non-destructive testing, structure and macro- and microhardness researches.

S. Tenerowicz

2011-07-01

77

Novel material properties of strained-layer superlattices  

International Nuclear Information System (INIS)

Strained-layer superlattices (SLS's) are high quality structures grown from lattice-mismatched semiconductor materials. Recent Sandia studies have demonstrated that a variety of SLS material properties can be tailored through the flexible choice of layer materials and thicknesses and through the use of quantum size effects, zone folding effects, and strain effects. The use of strained layers in SLS's allows these structures to exhibit a number of novel features. Examples of these features include: independently variable band gap and lattice constant using mismatched ternaries; strain-induced band gap shifts; and strain-modified effective masses. These features provide the opportunity for a variety of fundamental and applied materials studies using SLS systems

78

Electromagnetic cloaking by layered structure of homogeneous isotropic materials  

CERN Document Server

Electromagnetic invisibility cloak requires material with anisotropic distribution of the constitutive parameters deduced from a geometrical transformation as first proposed by Pendry et al. [Science 312, 1780 (2006)]. In this paper, we proposed a useful method to realize the required radius-dependent, anisotropic material parameters and to construct an electromagnetic cloak through concentric layered structure of thin, alternating layers of homogeneous isotropic materials. With proper design of the permittivity or the thickness ratio of the alternating layers, we demonstrated the low-reflection and power-flow bending properties of the proposed cloaking structure through rigorous analysis of the scattered electromagnetic fields. The proposed cloaking structure does not require anisotropy or inhomogeneity of the material constitutive parameters usually realized by metamaterials with subwavelength structured inclusions, therefore may lead to a practical path to an experimental demonstration of electromagnetic c...

Huang, Ying; Jian, Tian

2007-01-01

79

Properties of silicon-on-defect-layer material  

Energy Technology Data Exchange (ETDEWEB)

A new silicon material, silicon-on-defect-layer (SODL), has been measured by secondary ion mass spectrometry (SIMS) and spreading resistivity (SR) measurements. SIMS data show that the buried defect-layer in SODL consists of silicon oxide due to the gettering of intrinsic oxygen by proton-implanted damage. Furthermore, SODL procedure makes a silicon wafer contain much fewer oxygen in surface-layer on the defect-layer, resulting in a purified surface-layer. Measurements of SR indicate that the surface-layer of n-type silicon wafer was converted to p-type silicon after SODL procedure. A metal oxide semiconductor (MOS) device with a value of electron mobility in the inversion mode of 714 cm{sup 2}/(V {center_dot} s) was fabricated on SODL material. Like isolation function of a well in a complementary MOS (CMOS) device, the p-n junction in SODL material could play a role of isolation between the surface-layer and bulk. In addition, by reducing the implantation energy, SODL technology for making p-n junction, in which built-in field separates light-generated electrons and holes, is a candidate to make cheap solar cells by using low-quality low-cost silicon.

Li, J.; Jones, K.W. [Brookhaven National Lab., Upton, NY (United States); Coleman, J.H. [Plasma Physics Corp., Locust Valley, NY (United States); Yi, J.; Wallace, R.; Anderson, W.A. [State Univ. of New York, Buffalo, NY (United States)

1996-12-31

80

Incorporating microorganisms into polymer layers provides bioinspired functional living materials  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Artificial two-dimensional biological habitats were prepared from porous polymer layers and inoculated with the fungus Penicillium roqueforti to provide a living material. Such composites of classical industrial ingredients and living microorganisms can provide a novel form of functional or smart materials with capability for evolutionary adaptation. This allows realization of most complex responses to environmental stimuli. As a conceptual design, we prepared a material surface with self-cle...

Gerber, Lukas C.; Koehler, Fabian M.; Grass, Robert N.; Stark, Wendelin J.

2011-01-01

 
 
 
 
81

Contact mechanics of layered elastic materials: experiment and theory  

International Nuclear Information System (INIS)

This paper reports an experimental and theoretical investigation of the indentation of a layered elastic solid, with special reference to the surface force apparatus (SFA). The contacting surfaces of the SFA comprise a 3-layer material: a thin mica surface layer on a thicker epoxy layer supported by a thick silica substrate. An existing finite element analysis of the deformation of ideal mica/epoxy/silica surfaces used in the SFA is adapted to compare with the experimental measurements of the variation of contact size with load, both with and without adhesion at the interface. This is in marked difference to the Johnson, Kendall and Roberts (JKR) theory for homogeneous solids. Experiments and finite element calculations were also carried out on the elastic indentation of a thin (5.5 ?m) layer of mica on a very thick layer of epoxy (>100 ?m). As input data for the calculations, the elastic moduli of the mica and epoxy were measured in separate indentation experiments. The stiffness of a layered solid can be expressed by an 'effective modulus' Ee*, which has been deduced from the experimental measurements and compared with the theoretical values with fair success. The work of adhesion is commonly measured in the SFA by observing the 'pull-off force' to separate the surfaces. The theory shows that, for a layered solid, the pull-force can vary significantly from the JKR value for a homogeneous solid. In particular, it was found that the mica surfaccular, it was found that the mica surface energy, ?sv, measured by SFA experiments using crossed cylinders of mean radius R, where the materials are layered and the mica/mica adhesion is high, can vary with the pull-off force Fp according to Fp/4?R sv p/2?R, and for this particular experiment was given as ?sv = Fp/3.5 ?R as compared with ?sv = Fp/3?R for homogeneous materials

82

Sacrificial bonds and hidden length in biomaterials -- a kinetic description of strength and toughness in bone  

Science.gov (United States)

Sacrificial bonds and hidden length in structural molecules account for the greatly increased fracture toughness of biological materials compared to synthetic materials without such structural features, by providing a molecular-scale mechanism of energy dissipation. One example of occurrence of sacrificial bonds and hidden length is in the polymeric glue connection between collagen fibrils in animal bone. In this talk, we propose a simple kinetic model that describes the breakage of sacrificial bonds and the revelation of hidden length, based on Bell's theory. We postulate a master equation governing the rates of bond breakage and formation, at the mean-field level, allowing for the number of bonds and hidden lengths to take up non-integer values between successive, discrete bond-breakage events. This enables us to predict the mechanical behavior of a quasi-one-dimensional ensemble of polymers at different stretching rates. We find that both the rupture peak heights and maximum stretching distance increase with the stretching rate. In addition, our theory naturally permits the possibility of self-healing in such biological structures.

Lieou, Charles K. C.; Elbanna, Ahmed E.; Carlson, Jean M.

2013-03-01

83

Arhaeoastronomical analysis of Levinsadovka sacrificial complex (South Russia)  

Digital Repository Infrastructure Vision for European Research (DRIVER)

The article presents research data using arhaeoastronomical methods of Levinsadovka settlement sacrificial complex in Northern Black Sea coast. In this work, new method of accounting terrain elevations using topographic maps was developed in arhaeoastronomical studies. Calculations of azimuths of the sun and moon rise and set in the astronomically significant moments of the year were made and astronomical regularities in the organization of the sacrificial complex identified...

Vodolazhskaya, Larisa; Larenok, Vera

2013-01-01

84

Structure, Orientation and Stability of Lysozyme Confined in layered Materials  

Digital Repository Infrastructure Vision for European Research (DRIVER)

The confinement of lysozyme in 3 layered materials based on montmorillonite and lamellar double hydroxide exhibiting different surface charges was studied. The protein structure and orientation in these materials were determined by X-Ray diffraction, time resolved fluorescence and fluorescence anisotropy. For both Montmorillonite exchanged with sodium and modified with non-ionic surfactant (tri-ethylene glycol mono n-decyl ether), the lysozyme was found to be located in the interlayer space w...

Balme, Se?bastien; Gue?gan, Re?gis; Janot, Jean-marc; Jaber, Maguy; Lepoitevin, Mathilde; Dejardin, Philippe; Bourrat, Xavier; Motelica-heino, Mikael

2013-01-01

85

The effect of gamma irradiation on few layered graphene materials  

Digital Repository Infrastructure Vision for European Research (DRIVER)

The effect of -irradiation on the structure and composition of chemically synthesized few-layered graphene materials was studied. Fully oxidized graphene oxide and graphene nanoribbons, as well as their respective chemically post-reduced forms, were treated under -irradiation in an air-sealed environment. Three different irradiation doses of 60, 90 and 150 kGy were applied. Structure and composition of the irradiated materials were analyzed by X-ray diffraction (XRD), Fourier...

Anso?n Casaos, Alejandro; Pue?rtolas, J. A.; Pascual, F. J.; Herna?ndez-ferrer, J.; Castell, Pere; Benito, Ana M.; Maser, Wolfgang K.; Marti?nez, M. Teresa

2014-01-01

86

Thermal transport in layered materials for thermoelectrics and thermal management  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Atomic level thermal transport in layered materials, namely, Bi 2Te3 and graphene is investigated using first principles calculations, lattice dynamics (LD) calculations, molecular dynamics simulations, spectral phonon analysis and empirical modeling. These materials resemble geometrically while differ significantly in the nature of thermal transport. Because of their uniquely low/high thermal conductivities, they are of great interest in thermoelectrics and thermal management applications, r...

Qui, Bo

2012-01-01

87

CVD COATING OF CERAMIC LAYERS ON CERAMIC CUTTING TOOL MATERIALS  

Digital Repository Infrastructure Vision for European Research (DRIVER)

When forming cutting tool materials based on ceramic components, one must take into considration the combination of wear resistance and mechanical properties which can withstand unfavorable cutting conditions at the same time maintaining high strength and fracture toughness. Ceramic cutting tools which are designed for machining at high cutting speeds and which have high strength and fracture toughness can be formed by applying a thin layer of ceramic materials on the substrate in order to in...

Porat, R.

1991-01-01

88

Optimized Material For Bottom Layer Of Trilevel Resist System  

Science.gov (United States)

Requirements for the bottom layer of the trilevel resist system are examined with the aid of the SAMPLE simulator. Some conventional positive photoresists and our new bottom layer material RG-3900B are evaluated as a bottom layer. RG-3900B is a phenolic resin mixed with a novel azide compound. It is found that RG-3900B has the following excellent optical properties with relatively short baking time at about 200°C; it strongly absorbs the exposing light and is transparent at visible regions for alignment. Therefore, when applied as a bottom layer, it minimizes linewidth variations on highly reflective substrate topography without degradation of alignment accuracy. RG-3900B has been successfully applied to our various devices with multilevel metalization to obtain fine patterns.

Moriuchi, Noboru; Shirai, Seiichiro; Iwayanagi, Takao

1986-07-01

89

Thin layer laser bonding using spin-on-glass materials  

International Nuclear Information System (INIS)

We developed and characterized a new laser bonding process with a nano adhesive layer for transparent materials. The adhesive is spin-coated on a glass substrate and cured locally with a focused laser beam. The minimum viscosity of the adhesive is very low, so that a thin layer only a few hundred nanometers thick can be coated on a cover substrate. Laser irradiation from a Nd:YAG laser system with a wavelength of 1064 nm is employed as the curing source for the localized nano layer bonding process. The measured thickness of the bonding layer is in the range of 400 nm to 3 ?m. This process can be applied to the nano or micro bonding of various transparent systems such as flat panel displays, biochips, and heat-sensitive microelectronics. We present experimental results and discuss the process characteristics

90

Carbon and titanium based layers for wood-based material  

Directory of Open Access Journals (Sweden)

Full Text Available Purpose: The main purpose of this work was to work out the technology of manufacturing carbon and titanium based layers on the surfaces of sintered carbides machining edges used in furniture industry.Design/methodology/approach: A hybrid deposition system employing DC magnetron sputtering and radio frequency plasma assisted chemical vapour deposition (RF PACVD in one reaction chamber was used to manufacture Ti:C gradient layers. For the laboratory investigation layers were deposited on sintered carbide samples. Friction coefficient and SEM EDS analysis were made. For the exploitation tests layers were deposited on the commercial sintered carbide tools widely used in furniture industry.Findings: As the result of investigation it was noticed that Ti and C based gradient layers deposited on sintered carbides surfaces seems to be a very interesting alternative for standard non modified machining tools because of they noticeably decreased friction coefficient and improved durability.Practical implications: Presented technology is dedicated for furniture industry as a layer improving the cutting properties of the machining toolsOriginality/value: Application of carbon and titanium based layers deposited by hybrid deposition method on sintered carbide cutting edges for wood and wood-based materials machining.

W. Kaczorowski

2008-04-01

91

Acoustic waves in solid and fluid layered materials  

Science.gov (United States)

This is a comprehensive theoretical survey of acoustic wave propagation in layered materials including elastic, viscoelastic and piezoelectric layers. The phonon modes are particularly emphasized in the case of periodic multilayered structures such as superlattices though other layered materials such as adsorbed layers and quasiperiodic structures are also discussed. Besides the bulk waves propagating in the whole materials, specific attention is paid to the effect of inhomogeneities within the perfect superlattice such as a free surface (with or without a cap layer), a superlattice/substrate interface and a defect layer embedded in the superlattice. Such inhomogeneities are usually present in actual device structures as a support (substrate) or as a protection (cap layer) for the superlattice; the defect layers offer the possibility of wave filtering and sometimes they can be introduced as an imperfection during the epitaxial growth process. The superlattices are considered as semi-infinite or finite size structures. The symmetry of the materials are chosen such that the transverse acoustic waves are decoupled from the sagittal one (i.e., those having components of the acoustic displacement in the sagittal plane formed by the propagation direction and the normal to the interfaces). A general rule about the existence of localized surface modes in elastic, viscoelastic and piezoelectric semi-infinite superlattices with a free surface is presented. The adsorption of a hard material on the top of the superlattice (cap layer) has been shown to be appropriate for detecting experimentally high frequency guided modes within the adsorbed layer. Also, the superlattice/substrate interface may exhibit interface modes which are without analogue in the case of an interface between two homogeneous media. For a finite size superlattice, due to the interaction between the surface, interface and bulk waves, different localized and resonant modes are obtained and their properties are investigated. In particular, the effect of a buffer layer embedded between the superlattice and the substrate in confining guided modes in the superlattice is highlighted. These results are obtained in the frame of a Green's function formalism that enables us to deduce the dispersion curves, local and total densities of states, as well as the transmission and reflection coefficients and the corresponding phase times. In particular, an exact relation between the density of states and the phase times is pointed out. The application of elastic layered periodic structures as acoustic mirrors that exhibit total reflection of waves for all incident angles and polarizations in a given frequency range is indicated. These structures may also be used as acoustic filters when a defect layer is inserted within the finite size layered structure. A discussion is also included about some spectroscopic techniques used to probe the acoustic waves such as Raman and Brillouin light scattering and other acoustic techniques such as the surface acoustic waves and the picosecond laser techniques among others. A comparison of the theoretical results with experimental data available in the literature is also presented and the reliability of the theoretical predictions is indicated. Finally, other acoustic wave properties in quasiperiodic structures are briefly reviewed.

El Boudouti, E. H.; Djafari-Rouhani, B.; Akjouj, A.; Dobrzynski, L.

92

A study of layered lithium manganese oxide cathode materials  

Science.gov (United States)

Substituted layered sodium manganese oxide bronzes with the P2 structure were prepared by glycine-nitrate combustion synthesis. The Na in the as-prepared materials could be completely ion-exchanged for Li under mild conditions. All lithium manganese oxide compounds obtained after ion-exchange have O2 stacking of the layers. Cyclic voltammetry and stepped potential experiments on lithium cells containing these materials show that the main redox reaction around 3.1 V is a diffusion-controlled process and is completely reversible. O2-Li 0.6[Al 0.1Mn 0.85? 0.05]O 2 and O2-Li 0.6[Ni 0.1Mn 0.85? 0.05]O 2 are particularly promising as cathode materials in lithium cells because of the high reversible discharge capacities (180 mAh/g).

Eriksson, Tom A.; Doeff, Marca M.

93

Sacrificial template method of fabricating a nanotube  

Science.gov (United States)

Methods of fabricating uniform nanotubes are described in which nanotubes were synthesized as sheaths over nanowire templates, such as using a chemical vapor deposition process. For example, single-crystalline zinc oxide (ZnO) nanowires are utilized as templates over which gallium nitride (GaN) is epitaxially grown. The ZnO templates are then removed, such as by thermal reduction and evaporation. The completed single-crystalline GaN nanotubes preferably have inner diameters ranging from 30 nm to 200 nm, and wall thicknesses between 5 and 50 nm. Transmission electron microscopy studies show that the resultant nanotubes are single-crystalline with a wurtzite structure, and are oriented along the direction. The present invention exemplifies single-crystalline nanotubes of materials with a non-layered crystal structure. Similar "epitaxial-casting" approaches could be used to produce arrays and single-crystalline nanotubes of other solid materials and semiconductors. Furthermore, the fabrication of multi-sheath nanotubes are described as well as nanotubes having multiple longitudinal segments.

Yang, Peidong (Berkeley, CA); He, Rongrui (Berkeley, CA); Goldberger, Joshua (Berkeley, CA); Fan, Rong (El Cerrito, CA); Wu, Yi-Ying (Albany, CA); Li, Deyu (Albany, CA); Majumdar, Arun (Orinda, CA)

2007-05-01

94

KAPOOL experiments to simulate molten corium sacrificial-concrete interaction and gate opening in the EPR core catcher concept  

International Nuclear Information System (INIS)

In future light water reactors special devices (core catchers) might be required to prevent containment failure by basement erosion after reactor pressure vessel meltthrough during a core meltdown accident. In the case of a postulated core melt down accident in the EPR (European pressurized water reactor) the ex-vessel melt shall be retained and cooled in a special compartment inside the containment to exclude significant radioactive release to the environment. After failure of the reactor pressure vessel the core melt is retained in the reactor cavity for ? 1 h to pick up late melt releases. The reactor cavity is protected by a layer of sacrificial concrete and closed by a steel gate at the bottom. After meltthrough of this gate the core melt should be distributed homogeneously in a special spreading room. A series of experiments has been performed to investigate the erosion of the sacrificial concrete as well as the gate ablation using alumina-iron thermite melts as a simulant for the core melt. Two different sorts of sacrificial concrete have been studied so far: boro-silicate glass concrete and a concrete based on Fe2O3/SiO2. Erosion velocities of the sacrificial concrete, the homogeneity of the melt front and steel gate ablation results are presented in this report. (orig.)

95

Application of sacrificial concrete for the retention and conditioning of molten corium in the EPR core melt retention concept  

International Nuclear Information System (INIS)

The core melt stabilisation concept of the EPR involves an ex-vessel MCCI phase with sacrificial concrete for the retention and conditioning of molten corium before and after spreading. Both MCCI phases are simulated with the computer code COSACO, developed by Siemens/KWU. A brief overview of the main features of the code is given together with the results of a parametric study performed for the conservative assumption of a stepwise melt release from the RPV. This study demonstrates that the addition of sacrificial concrete in the reactor pit is an adequate means (i) to achieve a sufficient retention period and (ii) to oxidise all Zr initially present in the melt. For the spreading compartment, COSACO calculations predict a fully oxidised melt at the end of the MCCI. Its liquidus temperature, as confirmed by supplementary DTA-tests, is about 1850 C, and therefore significantly below the initial value of 2400 C. It is further demonstrated that the erosion of the provided sacrificial concrete will result in a density difference of about 2 Mg/m3 between the oxidic and metallic melt and thus in a stable layer inversion. These results justify the choice made for the composition of the sacrificial concrete. (orig.)

96

Investigation into conditions of producing two-layer materials with the surface layer of titanium carbide-steel  

International Nuclear Information System (INIS)

The possibility is studied of the production of iron-based twin-layer materials with addition of 1, 2, 3% Cu having a surface layer made up of titanium carbide - steel through the method of the simultaneous pressing and sintering together with the hot-pressing of the sintered layer to the sintered basic material. The strength of the layer coupling increases with a higher copper content and lower pressing force applied to the basic material. Thermal treatment enhances the layer hardness and practically does not effect on the layer coupling

97

Adhesion layer for etching of tracks in nuclear trackable materials  

Science.gov (United States)

A method for forming nuclear tracks having a width on the order of 100-200 nm in nuclear trackable materials, such as polycarbonate (LEXAN) without causing delamination of the LEXAN. The method utilizes an adhesion film having a inert oxide which allows the track to be sufficiently widened to >200 nm without delamination of the nuclear trackable materials. The adhesion film may be composed of a metal such as Cr, Ni, Au, Pt, or Ti, or composed of a dielectric having a stable surface, such as silicon dioxide (SiO.sub.2), silicon nitride (SiN.sub.x), and aluminum oxide (AlO). The adhesion film can either be deposited on top of the gate metal layer, or if the properties of the adhesion film are adequate, it can be used as the gate layer. Deposition of the adhesion film is achieved by standard techniques, such as sputtering or evaporation.

Morse, Jeffrey D. (Martinez, CA); Contolini, Robert J. (Lake Oswego, OR)

2001-01-01

98

Atomic Layer Deposition for the Conformal Coating of Nanoporous Materials  

Directory of Open Access Journals (Sweden)

Full Text Available Atomic layer deposition (ALD is ideal for applying precise and conformal coatings over nanoporous materials. We have recently used ALD to coat two nanoporous solids: anodic aluminum oxide (AAO and silica aerogels. AAO possesses hexagonally ordered pores with diameters d∼40 nm and pore length L∼70 microns. The AAO membranes were coated by ALD to fabricate catalytic membranes that demonstrate remarkable selectivity in the oxidative dehydrogenation of cyclohexane. Additional AAO membranes coated with ALD Pd films show promise as hydrogen sensors. Silica aerogels have the lowest density and highest surface area of any solid material. Consequently, these materials serve as an excellent substrate to fabricate novel catalytic materials and gas sensors by ALD.

Joe H. Satcher

2006-07-01

99

Study of materials for using at waste layer in repositories  

International Nuclear Information System (INIS)

This research has an objective to characterize Brazilian clays and to implant a data base containing the information obtained form tests and suppliers. Such information will allow to buy and and to select optimum material for its utilization in the stuffing layer. Brazilian suppliers were contacted for obtaining information and samples, the various clays were tested and these tests comprehend the following: identification of the mineral constituents, determination of the compaction curve as function of the humidity, hydraulic conductivity, humidity and organic material contents, cationic exchange capacity, specific surface, and etc

100

Atomic layer deposited aluminum oxide barrier coatings for packaging materials  

International Nuclear Information System (INIS)

Thin aluminum oxide coatings have been deposited at a low temperature of 80 oC on various uncoated papers, polymer-coated papers and boards and plain polymer films using the atomic layer deposition (ALD) technique. The work demonstrates that such ALD-grown Al2O3 coatings efficiently enhance the gas-diffusion barrier performance of the studied porous and non-porous materials towards oxygen, water vapor and aromas.

 
 
 
 
101

First-principles description of correlation effects in layered materials  

Digital Repository Infrastructure Vision for European Research (DRIVER)

We present a first-principles description of anisotropic materials characterized by having both weak (dispersionlike) and strong covalent bonds, based on the adiabatic-connection fluctuation-dissipation theorem with density functional theory. For hexagonal boron nitride the in-plane and out-of-plane bonding as well as vibrational dynamics are well described both at equilibrium and when the layers are pulled apart. Bonding in covalent and ionic solids is also described. The formalism allows us...

Marini, Andrea; Garci?a-gonza?lez, P.; Rubio Secades, A?ngel

2006-01-01

102

New buffer layer materials for CIGS solar cells  

Energy Technology Data Exchange (ETDEWEB)

The compound semiconductor CuIn{sub x}Ga{sub (1-x)}Se{sub 2} (CIGSE) are used as absorber material in thin-film photovoltaic cells. In conventional CIGSE based solar cells a thin CdS layer (buffer) significantly improves the photovoltaic performance and efficiencies up to 19.9% have been realized. Since Cd is a toxic heavy metal there is a demand for suitable substitute materials. The first requirements for these materials are an adequate band gap, a crystal structure compatible to that of CIGSE, and an n-type conductivity. An interesting class of materials are half-Heuslers, which are ternary compounds with a C1b MgAgAs structure. For many half-Heusler compounds the crystal structure matches well with the layer of the tetragonal CIGS unit cell. Using ab initio calculations based on B3LYP hybrid functionals, we have studied electronic properties of the most promising half-Heusler materials. Our results affirm the band gap rule for 8-electron half- Heuslers presented.

Gruhn, Thomas; Felser, Claudia [Institute of Inorganic and Analytical Chemistry, Johannes Gutenberg University, Mainz (Germany); Kieven, David [Helmholtz-Zentrum Berlin fuer Materialien und Energie GmbH, Berlin (Germany)

2009-07-01

103

Self assembled multi-layer nanocomposite of graphene and metal oxide materials  

Science.gov (United States)

Nanocomposite materials having at least two layers, each layer consisting of one metal oxide bonded to at least one graphene layer were developed. The nanocomposite materials will typically have many alternating layers of metal oxides and graphene layers, bonded in a sandwich type construction and will be incorporated into an electrochemical or energy storage device.

Liu, Jun; Aksay, Ilhan A; Choi, Daiwon; Kou, Rong; Nie, Zimin; Wang, Donghai; Yang, Zhenguo

2013-10-22

104

Self assembled multi-layer nanocomposite of graphene and metal oxide materials  

Energy Technology Data Exchange (ETDEWEB)

Nanocomposite materials having at least two layers, each layer consisting of one metal oxide bonded to at least one graphene layer were developed. The nanocomposite materials will typically have many alternating layers of metal oxides and graphene layers, bonded in a sandwich type construction and will be incorporated into an electrochemical or energy storage device.

Liu, Jun; Choi, Daiwon; Kou, Rong; Nie, Zimin; Wang, Donghai; Yang, Zhenguo

2014-09-16

105

Oxygen diffusion barriers using a new sacrificial design concept for future high-density memory devices  

Science.gov (United States)

We emphasize the importance of the new design concept for diffusion barriers in high-density memory capacitors. RuTiN and RuTiO films are proposed as sacrificial oxygen diffusion barriers. They showed much lower sheet resistance up to 800 °C than various barriers including binary and ternary nitrides, reported by others. The contact resistance for both the Pt/RuTiN/TiSix/n++poly-plug/n+channel layer/Si and the Pt/RuTiO/RuTiN/TiSix/n++poly-plug/n+channel layer/Si contact structures, the most important electrical parameter for the diffusion barrier in the bottom-electrode structure of capacitors, exhibited values as low as 5 k?, even after annealing up to 750 °C. When each RuTiN and TiN film is inserted as a glue layer between the bottom electrode Pt layer in the CVD-BST simple stack-type structure, the thermal stability of the RuTiN glue layer is observed to be 150 °C higher than that of the TiN glue layer. Moreover, the capacitance of the PVD-BST simple stack-type structure with a TiN glue layer initially degrades after annealing at 500 °C, and thereafter failed completely. In the case of RuTiN and the RuTiO/RuTiN glue layers, however, the capacitance continuously increased up to 550 °C. These new experimental results accommodate the introduction of the sacrificial design concept of diffusion barriers against oxygen in high-density memory capacitors.

Yoon, D. S.; Roh, J. S.

106

Materials science and technology strained-layer superlattices materials science and technology  

CERN Document Server

The following blurb to be used for the AP Report and ATI only as both volumes will not appear together there.****Strained-layer superlattices have been developed as an important new form of semiconducting material with applications in integrated electro-optics and electronics. Edited by a pioneer in the field, Thomas Pearsall, this volume offers a comprehensive discussion of strained-layer superlattices and focuses on fabrication technology and applications of the material. This volume combines with Volume 32, Strained-Layer Superlattices: Physics, in this series to cover a broad spectrum of topics, including molecular beam epitaxy, quantum wells and superlattices, strain-effects in semiconductors, optical and electrical properties of semiconductors, and semiconductor devices.****The following previously approved blurb is to be used in all other direct mail and advertising as both volumes will be promoted together.****Strained-layer superlattices have been developed as an important new form of semiconducting ...

Beer, Albert C; Pearsall, Thomas P

1991-01-01

107

Gamma radiation transport and scattering in layers of material  

International Nuclear Information System (INIS)

A program was written allowing to model, using the Monte Carlo method, gamma radiation transport through homogeneous and heterogeneous material under given geometrical conditions. Modelling all basic types of interactions it was found that coherent scattering has great infiuence on the value of albedo. Further computations showed that the dependence on atomic number Z of the probability of impingement of backscattered photons on the detector, is a compticated curve with maxima in every group of the periodical table. The shape of the curve is influenced by the dependence of albedo on Z. The said program was used to compute the probability of gamma backscattering from layers of material with a thickness less than the saturation thickness. Also computed were the values of gamma radiation buildup factors, and the configuration was designed for measuring material density using gamma radiation backscattering under different measuring conditions. (M.D.)

108

Features of heat treatment of highly porous layered materials ??????????? ???????? ????????? ???????? ?????????????? ??????????  

Directory of Open Access Journals (Sweden)

Full Text Available Effectiveness of thermal insulation products is determined by a set of criteria that can be expressed in terms of energy costs: reduction of the cost of heating (the main criterion, energy consumption in the course of construction, energy consumption in the course of production of materials having pre-set properties, and service durability of the material.On the one hand, service durability (as a property is generated in the course of material production, and on the other hand, it depends on the conditions that the material is exposed to in the course of any construction process. The same parameter affects energy-related criteria. Insulation replacement or unplanned repairs add supplementary energy costs.The manufacturing process of thermal insulation materials contemplates processing of a significant amount of non-renewable natural resources, namely, fuel combustion. Optimization of these costs is necessary and possible through appropriate organization of processes, including the process of heat treatment of products.Layered materials can improve the product performance and durability. Production and heat treatment of mineral fibers are the most energy-consuming steps of the mineral wool production. Optimization of these processes can involve significant economic effects.??????? ???????????? ????????????????? ?????????? ?????? ? ???????????? ????????????? ?????????? ???????????????? ????????? ????????, ? ????????? ????????? ???????. ??????????? ???? ?????? ?????????? ? ???????? ?? ???? ?????????? ??????????? ??????????????? ?????????, ? ?.?. ???????? ???????? ????????? ???? ???????. ? ??????????? ?????????????? ??????? ???????? ?????????? ?? ??????? ?????????? ???????? ????????? ???????????? ??????? ? ??? ???????? ?????????. ??????????? ???? ????????? ????????? ????????? ????????????? ?????????????? ???????.

Zhukov Aleksey Dmitrievich

2013-05-01

109

Models of failure in compression of layered materials  

DEFF Research Database (Denmark)

Compressive failure of fibre reinforced or layered materials by fibre kinking, matrix splitting and fibre/matrix debonding is analysed, The main focus is on brittle matrix composites, however, the analysis of effects due to debonding is carried out in a general framework allowing for arbitrary time-independent plasticity of the layers. Fibre kinking and matrix splitting are regarded as competing failure modes with the conditions governing the active mode depending on the biaxial stress state in the composite and a combination of micro mechanical parameters. Two criteria for matrix splitting, and two models for the evolution of micro cracks in the matrix have been discussed. (C) 1999 Elsevier Science Ltd. All rights reserved.

Jensen, Henrik Myhre

1999-01-01

110

An innovative series of layered nanostructured aminoalkylsilica hybrid material  

International Nuclear Information System (INIS)

An innovative series of silica-based hybrid materials containing pendant cationic ammoniumpropyl groups was obtained using the sol-gel method, by varying the molar ratio of the inorganic and organic precursors. Thermogravimetric analysis showed that samples were thermally stable up to 260 deg C. Results obtained by X-ray diffractometry, transmission electron microscopy, 29Si nuclear magnetic resonance and elemental analysis were compatible with a silsesquioxane layered structural model showing basal distances up to 5.4 nm, containing amorphous silica in the interlayer space. (author)

111

First-principles description of correlation effects in layered materials.  

Science.gov (United States)

We present a first-principles description of anisotropic materials characterized by having both weak (dispersionlike) and strong covalent bonds, based on the adiabatic-connection fluctuation-dissipation theorem with density functional theory. For hexagonal boron nitride the in-plane and out-of-plane bonding as well as vibrational dynamics are well described both at equilibrium and when the layers are pulled apart. Bonding in covalent and ionic solids is also described. The formalism allows us to ping down the deficiencies of common exchange-correlation functionals and provides insight toward the inclusion of dispersion interactions into the correlation functional. PMID:16712011

Marini, Andrea; García-González, P; Rubio, Angel

2006-04-01

112

Failure modes and materials design for biomechanical layer structures  

Science.gov (United States)

Ceramic materials are finding increasing usage in the area of biomechanical replacements---dental crowns, hip and bone implants, etc.---where strength, wear resistance, biocompatibility, chemical durability and even aesthetics are critical issues. Aesthetic ceramic crowns have been widely used in dentistry to replace damaged or missing teeth. However, the failure rates of ceramic crowns, especially all-ceramic crowns, can be 1%˜6% per year, which is not satisfactory to patients. The materials limitations and underlying fracture mechanisms of these prostheses are not well understood. In this thesis, fundamental fracture and damage mechanisms in model dental bilayer and trilayer structures are studied. Principle failure modes are identified from in situ experimentation and confirmed by fracture mechanics analysis. In bilayer structures of ceramic/polycarbonate (representative of ceramic crown/dentin structure), three major damage sources are identified: (i) top-surface cone cracks or (ii) quasiplasticity, dominating in thick ceramic bilayers; (iii) bottom-surface radial cracks, dominating in thin ceramic bilayers. Critical load P for each damage mode are measured in six dental ceramics: Y-TZP zirconia, glass-infiltrated zirconia and alumina (InCeram), glass-ceramic (Empress II), Porcelain (Mark II and Empress) bonded to polymer substrates, as a function of ceramic thickness d in the range of 100 mum to 10 mm. P is found independent of d for mode (i) and (ii), but has a d 2 relations for mode (iii)---bottom surface radial cracking. In trilayer structures of glass/core-ceramic/polycarbonate (representing veneer porcelain/core/dentin structures), three inner fracture origins are identified: radial cracks from the bottom surface in the (i) first and (ii) second layers; and (iii) quasiplasticity in core-ceramic layer. The role of relative veneer/core thickness, d1/d 2 and materials properties is investigated for three core materials with different modulus (114--270GPa) and strength (400--1400MPa): Y-TZP zirconia, InCeram alumina and Empress II glass-ceramic. Explicit relations for the critical loads P to produce these different damage modes in bilayer and trilayer structures are developed in terms of basic material properties (modulus E, strength, hardness H and toughness T) and geometrical variables (thickness d and contact sphere radius r). These experimentally validated relations are used to design of optimal material combinations for improved fracture resistance and to predict mechanical performance of current dental materials.

Deng, Yan

113

Universal method for creating optically active nanostructures on layered materials.  

Science.gov (United States)

The ability to form patterned surface nanostructures has revolutionized the miniaturization of electronics and led to the discovery of emergent behaviors unseen in macroscopic systems. However, the creation of such nanostructures typically requires multiple processing steps, a high level of technical expertise, and highly sophisticated equipment. In this work, we have discovered a simple method to create nanostructures with control size and positioning in a single processing step using a standard scanning electron microscope. The technique can be applied to a wide range of systems and was successful in every layered material tested. Patterned nanostructures were formed on graphite, topological insulators, novel superconductors, and layered transition metal dichalcogenides. The nanostructures were formed via the incorporation of carbon nanoparticles into the samples in a novel form of intercalation. It appears that the electron beam interacts with residual organic molecules available on the sample surface, making it possible for them to intercalate between the layers in their crystal structure and break down into carbon. These carbon nanoparticles have strong broad-wavelength interactions in the visible light range, making these nanostructures easily detectable in an optical microscope and of interest for a range of nanoscale electro-optical devices. PMID:24793140

Kidd, Timothy E; O'Shea, Aaron; Beck, Benjamin; He, Rui; Delaney, Conor; Shand, Paul M; Strauss, Laura H; Stollenwerk, Andrew; Hurley, Noah; Spurgeon, Kyle; Gu, Genda

2014-05-27

114

Utilization of Industrial Waste Material in GSB Layer  

Directory of Open Access Journals (Sweden)

Full Text Available India has series of steel plant clusters located along its length and breadth of the territory. Several million metric tons of iron and steel are produced in these plants annually. Along with the production of iron and steel, huge quantities of solid wastes like blast furnace slag and steel slag as well as other wastes such as flue dust, blast furnace sludge, and refractories are also being produced in these plants. These solid wastes can be used as non-traditional/non-conventional aggregates in pavement construction due to acute scarcity of traditional/conventional road construction materials. A study was conducted to investigate the possibility of using Granulated Blast Furnace Slag (GBFS with various blended mixes of traditional/conventional aggregates in subbase layer with different percentages. This study also presents the result of experimental investigation on the influence of Rice husk ash (RHA on the index properties of Red soil which is used as filler material in subbase layer.

U Arun Kumar

2014-08-01

115

Sacrificial bonds and hidden length in biomaterials -- a kinetic, constitutive description of strength and toughness in bone  

CERN Document Server

Sacrificial bonds and hidden length in structural molecules account for the greatly increased fracture toughness of biological materials compared to synthetic materials without such structural features, by providing a molecular-scale mechanism for energy dissipation. One example is in the polymeric glue connection between collagen fibrils in animal bone. In this paper, we propose a simple kinetic model that describes the breakage of sacrificial bonds and the release of hidden length, based on Bell's theory. We postulate a master equation governing the rates of bond breakage and formation. This enables us to predict the mechanical behavior of a quasi-one-dimensional ensemble of polymers at different stretching rates. We find that both the rupture peak heights and maximum stretching distance increase with the stretching rate. In addition, our theory naturally permits the possibility of self-healing in such biological structures.

Lieou, Charles K C; Carlson, Jean M

2013-01-01

116

Sacrificial bonds and hidden length in biomaterials: A kinetic constitutive description of strength and toughness in bone  

Science.gov (United States)

Sacrificial bonds and hidden length in structural molecules account for the greatly increased fracture toughness of biological materials compared to synthetic materials without such structural features by providing a molecular-scale mechanism for energy dissipation. One example is in the polymeric glue connection between collagen fibrils in animal bone. In this paper we propose a simple kinetic model that describes the breakage of sacrificial bonds and the release of hidden length, based on Bell's theory. We postulate a master equation governing the rates of bond breakage and formation. This enables us to predict the mechanical behavior of a quasi-one-dimensional ensemble of polymers at different stretching rates. We find that both the rupture peak heights and maximum stretching distance increase with the stretching rate. In addition, our theory naturally permits the possibility of self-healing in such biological structures.

Lieou, Charles K. C.; Elbanna, Ahmed E.; Carlson, Jean M.

2013-07-01

117

Materiales laminares pilareados: preparación y propiedades Pillared layered materials: preparation and properties  

Digital Repository Infrastructure Vision for European Research (DRIVER)

The structure of several types of layered materials will be described. These include clays, layered double hydroxides, group IV metal phosphates and other layered materials. The preparation of the pillared materials and pillaring agents will be presented along with a description of the properties and applications of the products.

Pergher, Sibele B. C.; Avelino Corma; Vicente Fornes

1999-01-01

118

Fabrication of Meso-Porous Sintered Metal Thin Films by Selective Etching of Silica Based Sacrificial Template  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Meso-porous metal materials have enhanced surface energies offering unique surface properties with potential applications in chemical catalysis, molecular sensing and selective separation. In this paper, commercial 20 nm diameter metal nano-particles, including silver and copper were blended with 7 nm silica nano-particles by shear mixing. The resulted powders were cold-sintered to form dense, hybrid thin films. The sacrificial silica template was then removed by selective etching in 12 wt% h...

Dumee, Ludovic F.; Fenghua She; Mikel Duke; Stephen Gray; Peter Hodgson; Lingxue Kong

2014-01-01

119

Physico-chemical and material aspects of the core melt retention concept of the EPR  

International Nuclear Information System (INIS)

To maintain containment integrity and to reduce the radiological consequences of a postulated severe accident, the core melt stabilization concept of the EPR employs sacrificial materials for melt conditioning and protective materials to avoid basemat penetration. The sacrificial materials added to the core melt fully oxidize the chemically aggressive metallic zirconium, significantly reduce the initially very high melt temperature and lead to a favorable layer inversion in the spreading room. Experimental and theoretical work shows that the sacrificial concrete lowers the liquidus temperature of the oxidic corium melt down to 1800-1850 C. This in turn reduces the long-term temperatures of the molten corium and hence also the thermochemical challenges to the protective layer in the spreading room. The spreading area consists of three layers of different materials (from top to bottom): (i) sacrificial concrete, (ii) sacrificial metal and (iii) zirconia (ZrO2) as protective material. Due to the layer inversion achieved by the sacrificial material a contact between the oxidic melt and the protective layer with corresponding thermochemical interactions is avoided. The protective material is in contact with a metal melt (Fe, 3-7 w% Cr, 7 w% Ni). This metal melt is covered by a less dense oxidic melt (UO2, ZrO2, FeO, SiO2, Al2O3, CaO,..) which gives rise to a certain oxygen concentration in the metal melt. Thoxygen concentration in the metal melt. The thermochemical stability of ZrO2 is predominantly influenced by the temperature and oxygen concentration in the metallic melt. The parameter governing the stability against chemical dissolution is the activity of FeO in the metal melt which is related to the oxygen concentration. Performed theoretical and experimental investigations demonstrate that under EPR conditions this FeO activity always remains below the threshold value for the formation of liquid ZrO2-FeO phases and therefore dissolution of ZrO2 can be excluded. The presence of the weak desoxidant chromium in the metallic melt is beneficial and further increases the safety margin compared to a chromium-free metal melt. Technological application forms of ZrO2 are sinteractive ramming mass, sintered ceramic bricks or ZrO2 concretes. At the current state of knowledge, ramming mass is the most promising application form for the bottom area of the spreading room. Laboratory tests have shown that, when heating ramming mass by a metallic melt under

120

"Determination of mechanical strength of different material double-layer rectangular tablets "  

Digital Repository Infrastructure Vision for European Research (DRIVER)

The mechanical strength of different material composite beams were assessed. All tablets were subjected to three-point bending test. For the preparation of tablets, the material of the lower layer was initially put in the die and compacted by a certain pressure. The second material was then put upon the first layer. Modulus of elasticity of the selected materials were used to interpret the behaviour of the top and bottom layers of the different materials composite tablets. Determination of th...

"Haririan I; Tajkey J; Jm, Newton

2000-01-01

 
 
 
 
121

Gate induced superconductivity in layered material based electronic double layer field effect transistors  

Energy Technology Data Exchange (ETDEWEB)

Applying the principle of field effect transistor to layered materials provides new opportunities to manipulate their electronic properties for interesting sciences and applications. Novel gate dielectrics like electronic double layer (EDL) formed by ionic liquids are demonstrated to achieve an electrostatic surface charge accumulation on the order of 10{sup 14} cm{sup -2}. To realize electric field-induced superconductivity, we chose a layered compound: ZrNCl, which is known to be superconducting by introducing electrons through intercalation of alkali metals into the van der Waals gaps. A ZrNCl-based EDL transistor was micro fabricated on a thin ZrNCl single crystal made by mechanical micro-cleavage. Accumulating charges using EDL gate dielectrics onto the channel surface of ZrNCl shows effective field effect modulation of its electronic properties. Sheet resistance of ZrNCl EDL transistor is reduced by applying a gate voltage from 0 to 4.5 V. Temperature dependence of sheet resistance showed clear evidence of metal-insulator transition upon gating, observed at a gate voltage higher than 3.5 V. Furthermore, gate-induced superconductivity took place after metal-insulator transition when the transistor is cooled down to about 15 K.

Ye, J.T., E-mail: yejianting@imr.tohoku.ac.j [Institute for Materials Research, Tohoku University, Sendai 980-8577 (Japan); Inoue, S.; Kobayashi, K.; Kasahara, Y.; Yuan, H.T.; Shimotani, H.; Iwasa, Y. [Institute for Materials Research, Tohoku University, Sendai 980-8577 (Japan)

2010-12-15

122

Layered cathode materials for lithium ion rechargeable batteries  

Science.gov (United States)

A number of materials with the composition Li.sub.1+xNi.sub..alpha.Mn.sub..beta.Co.sub..gamma.M'.sub..delta.O.sub.2-- zF.sub.z (M'=Mg,Zn,Al,Ga,B,Zr,Ti) for use with rechargeable batteries, wherein x is between about 0 and 0.3, .alpha. is between about 0.2 and 0.6, .beta. is between about 0.2 and 0.6, .gamma. is between about 0 and 0.3, .delta. is between about 0 and 0.15, and z is between about 0 and 0.2. Adding the above metal and fluorine dopants affects capacity, impedance, and stability of the layered oxide structure during electrochemical cycling.

Kang, Sun-Ho (Naperville, IL); Amine, Khalil (Downers Grove, IL)

2007-04-17

123

Advanced Lithium Ion Battery Materials Prepared with Atomic Layer Deposition  

Science.gov (United States)

As the world consumes the dwindling supply of fossil fuels, an alternative to gasoline powered vehicles will become necessary. Lithium ion batteries (LIBs) are emerging as the dominant power source for portable electronics, and are seen as a promising energy source in the development of electric vehicles. Current LIB technology is not well suited for vehicles, increases in the energy density, power density and durability are needed before LIB are ready for widespread use in electric vehicles. LiCoO2 and graphite are the dominant cathode and anode active materials, respectively in LIBs. On the cathode side, instabilities in LiCoO 2 can lead to the deterioration of the LIB. Decomposition of electrolyte on the graphite anode surface to form a solid-electrolyte interphase (SEI) consumes lithium from the cathode resulting in a lower battery capacity. Instabilities in the in the SEI can result in catastrophic battery failure. Previous studies have employed metal oxides films, typically grown with wet chemical techniques, to stabilize LiCoO2 and mitigate the formation of the SEI on graphite. The thicknesses of films grown with wet chemical techniques was typically ˜50--1000 A. In order to achieve higher power densities, the particle size of LIB active materials is being scaled down. As active materials get smaller the mass contribution of a protective film can become a significant fraction of the total mass. Atomic layer deposition (ALD) has been used to grow ultra thin films of Al2O3 on LiCoO2 and graphite. By altering the interaction between the active material and the battery electrolyte it was possible to improve the stability of both LiCoO2 and graphite electrodes in LIBs. In the case of graphite, the Al2O3 film may be thought of as an artificial SEI. During the initial charge-discharge cycle of a LIB, the electrolyte decomposes on the anode to form the SEI. The formation of the SEI is believed to prevent further decomposition of the electrolyte on the anode surface. The SEI contains electrolyte decomposition products including Li2CO3, Li2O, LiOH, LiF and R-OLi. In order to grow a truly artificial SEI on the graphite anode, i.e. grow a film that mimics the SEI that forms during charge-discharge cycling, new ALD chemistries for the growth of Li2CO3 and LiOH have been developed. The ALD of an artificial SEI layer may limit lithium loss and improve the capacity stability during charge-discharge cycles.

Cavanagh, Andrew S.

124

Arhaeoastronomical analysis of Levinsadovka sacrificial complex (South Russia)  

CERN Document Server

The article presents research data using arhaeoastronomical methods of Levinsadovka settlement sacrificial complex in Northern Black Sea coast. In this work, new method of accounting terrain elevations using topographic maps was developed in arhaeoastronomical studies. Calculations of azimuths of the sun and moon rise and set in the astronomically significant moments of the year were made and astronomical regularities in the organization of the sacrificial complex identified. Related to the moon directions, as the most dedicated, identified. Revealed that the stone tools and fragments, used as sacrifices, mark the direction to the northern minor standstill moonrise. A similar situation was found on two archaeological sites: in Bezymennoye II settlement South sanctuary and in Pustynka settlement religious building. Drawing on ethnographic and folklore data, it is concluded about semiotic connection of stone tools, found in these religious constructions, with the "thunderstones" and meteorites.

Vodolazhskaya, Larisa

2013-01-01

125

Photoreduction of graphene oxide enhanced by sacrificial agents.  

Science.gov (United States)

In this work, the photoreduction of graphene oxides (GOs) was carried out in the presence of a sacrificial agent of Na2S/Na2SO3 and triethanolamine (TEA) separately in the solution. The photoreduction of GOs was enhanced with the addition of the sacrificial agent, which was examined in terms of reduction extent and needed reduction period. The quench of the GO emission was observed in the photoluminescence spectra of both GO solutions with Na2S/Na2SO3 and TEA. Although both sacrificial agents facilitated the charge transfer in the irradiated GO solutions, the aggregation of GO/reduced GO (RGO) occurred in the Na2S/Na2SO3-contained solution during photoreduction, which limited further photoreduction of GOs with the assistance of Na2S/Na2SO3. By keeping good dispersion characteristic during the whole process, the photoreduction efficiency of GO in the presence of TEA was therefore superior to that with the assistance of Na2S/Na2SO3. PMID:25454453

Cho, Hsun-Wei; Wu, Jih-Jen

2015-01-15

126

Large-scale simulations of layered double hydroxide nanocomposite materials  

Science.gov (United States)

Layered double hydroxides (LDHs) have the ability to intercalate a multitude of anionic species. Atomistic simulation techniques such as molecular dynamics have provided considerable insight into the behaviour of these materials. We review these techniques and recent algorithmic advances which considerably improve the performance of MD applications. In particular, we discuss how the advent of high performance computing and computational grids has allowed us to explore large scale models with considerable ease. Our simulations have been heavily reliant on computational resources on the UK's NGS (National Grid Service), the US TeraGrid and the Distributed European Infrastructure for Supercomputing Applications (DEISA). In order to utilise computational grids we rely on grid middleware to launch, computationally steer and visualise our simulations. We have integrated the RealityGrid steering library into the Large-scale Atomic/Molecular Massively Parallel Simulator (LAMMPS) 1 . which has enabled us to perform re mote computational steering and visualisation of molecular dynamics simulations on grid infrastruc tures. We also use the Application Hosting Environment (AHE) 2 in order to launch simulations on remote supercomputing resources and we show that data transfer rates between local clusters and super- computing resources can be considerably enhanced by using optically switched networks. We perform large scale molecular dynamics simulations of MgiAl-LDHs intercalated with either chloride ions or a mixture of DNA and chloride ions. The systems exhibit undulatory modes, which are suppressed in smaller scale simulations, caused by the collective thermal motion of atoms in the LDH layers. Thermal undulations provide elastic properties of the system including the bending modulus, Young's moduli and Poisson's ratios. To explore the interaction between LDHs and DNA. we use molecular dynamics techniques to per form simulations of double stranded, linear and plasmid DNA up to 480 base pairs in length intercalated within LDHs. Our models are found to be in agreement with experimental observations, according to which hydration is a crucial factor in determining the structural stability of DNA. At elevated tem peratures and pressures, the structural stability of LDH-intercalated DNA is substantially enhanced as compared to DNA in bulk water. We also discuss how the properties of LDHs are modified due to DNA intercalation. Our studies show that LDHs are flexible enough to deform around bulky intercalants such as DNA. The flexibility of layered materials has been shown to affect the pathway by which intercalation occurs. Recent experimental studies of LDHs have shown that these minerals can form staged intermediate structures during intercalation. However, the mechanism which produces staged structures remains un determined. We simulated three differently stacked structures and show that even though the structures under study are all energetically very similar, overall there is greater diffusion of DNA strands in a Daumas-Herold configuration compared to a Rudorff model and a stage-1 structure. The picture on the titlepage was produced using a visualisation package called Visual Molecular Dy namics (VMD) and represents a plasmid strand of DNA containing 480 base pairs intercalated inside an LDH. Only one layer of the LDH is displayed and water molecules have been hidden in order to aid viewing of the structure. The visualisation was produced from our largest simulation which contained 1,157,038 atoms, with lateral dimensions of 588.3Ax677.7A.

Thyveetil, Mary-Ann

127

PDMS as a sacrificial substrate for SU-8-based biomedical and microfluidic applications  

International Nuclear Information System (INIS)

We describe a new fabrication process utilizing polydimethylesiloxane (PDMS) as a sacrificial substrate layer for fabricating free-standing SU-8-based biomedical and microfluidic devices. The PDMS-on-glass substrate permits SU-8 photo patterning and layer-to-layer bonding. We have developed a novel PDMS-based process which allows the SU-8 structures to be easily peeled off from the substrate after complete fabrication. As an example, a fully enclosed microfluidic chip has been successfully fabricated utilizing the presented new process. The enclosed microfluidic chip uses adhesive bonding technology and the SU-8 layers from 10 µm to 450 µm thick for fully enclosed microchannels. SU-8 layers as large as the glass substrate are successfully fabricated and peeled off from the PDMS layer as single continuous sheets. The fabrication results are supported by optical microscopy and profilometry. The peel-off force for the 120 µm thick SU-8-based chips is measured using a voice coil actuator (VCA). As an additional benefit the release step leaves the input and the output of the microchannels accessible to the outside world facilitating interconnecting to the external devices

128

Layer-by-layer analysis of hydrogen in structural materials on the base of reflected electron spectroscopy  

International Nuclear Information System (INIS)

On the base of reflected electron spectroscopy the techniques of layer-by-layer analysis of hydrogen concentration in structural materials affected to thermonuclear plasma are developed. The given technique of nondestructive control may be used for analysis of thermonuclear reactor nodes and components connecting with plasma and for studying of hydrogen interaction with different materials using in hydrogen energetics. The program of statistical simulation of spectra of elastically reflected electrons from inhomogeneous media are created

129

Layer continuity in accumulative roll bonding of dissimilar material combinations  

International Nuclear Information System (INIS)

Highlights: • Instability in the strong layer has been observed by secondary electron micrographs and orientation imaging micrographs. • Tensile tests and three point bend tests revealed the detrimental effects of layer instability on mechanical properties. • DEFORM 2D simulations revealed a form of zigzag shear instability. • The instability observed in micrographs and simulations are in good conformity. • Explanations and analytical estimates of the necking in the hard layers that were proposed earlier are disputed. - Abstract: Strips were made by accumulative roll bonding of up to 64 alternating layers of an AA3103 alloy and either commercial purity copper or CuZn20 brass as the second type of layer. With increasing number of accumulative roll bonding cycles the layered structure became unstable. Instability in the strongest layer observed by secondary electron micrographs and orientation imaging micrographs revealed shear bands through the strong layers. The influence of the layer instability on the mechanical properties was investigated by tensile tests and three point bending tests. Numerical simulations using the commercial finite element software DEFORM 2D were used for investigating the instability mechanism in deformation of the multilayers. It is argued that the earlier proposed explanations and analytical estimates of the necking in the hard layers due to internal stresses do not apply. Instead the onset of the instability is in the form of a zigzag-shear instability, where the layers experience periodic increased thinning and bending

130

Laminated metal composite formed from low flow stress layers and high flow stress layers using flow constraining elements and making same  

Science.gov (United States)

A laminated metal composite of low flow stress layers and high flow stress layers is described which is formed using flow constraining elements, preferably in the shape of rings, individually placed around each of the low flow stress layers while pressure is applied to the stack to bond the layers of the composite together, to thereby restrain the flow of the low flow stress layers from the stack during the bonding. The laminated metal composite of the invention is made by the steps of forming a stack of alternate layers of low flow stress layers and high flow stress layers with each layer of low flow stress material surrounded by an individual flow constraining element, such as a ring, and then applying pressure to the top and bottom surfaces of the resulting stack to bond the dissimilar layers together, for example, by compression rolling the stack. In a preferred embodiment, the individual flow constraining elements surrounding the layers of low flow stress material are formed of a material which may either be the same material as the material comprising the high flow stress layers, or have similar flow stress characteristics to the material comprising the high flow stress layers. Additional sacrificial layers may be added to the top and bottom of the stack to avoid damage to the stack during the bonding step; and these additional layers may then be removed after the bonding step.

Syn, Chol K. (Moraga, CA); Lesuer, Donald R. (Livermore, CA)

1995-01-01

131

Carbon and titanium based layers for wood-based material  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Purpose: The main purpose of this work was to work out the technology of manufacturing carbon and titanium based layers on the surfaces of sintered carbides machining edges used in furniture industry.Design/methodology/approach: A hybrid deposition system employing DC magnetron sputtering and radio frequency plasma assisted chemical vapour deposition (RF PACVD) in one reaction chamber was used to manufacture Ti:C gradient layers. For the laboratory investigation layers were deposited on sinte...

Kaczorowski, W.; Batory, D.

2008-01-01

132

Surface modification of layered zirconium phosphates: a novel pathway to multifunctional materials.  

Science.gov (United States)

The intercalation of inorganic layered materials has resulted in a wide range of applicability. In such cases the applicability of the material is largely dependent upon the species intercalated within the layer, and the layered material acts largely as a host. Recently, the surface modification of inorganic layered materials has been investigated and it has been shown that the exterior layers can be exclusively functionalized. The advent of surface chemistry allows for the synthesis of particles with both a controlled interlayer and surface. This approach can be used to tailor nanoparticles for specific applications. Herein we review the surface chemistry of ?-zirconium bis(monohydrogen orthophosphate) monohydrate (Zr(HPO4)2·H2O, ?-ZrP) along with some applications of recent interest. Not only can these reactions be applied to ?-ZrP, but similar chemistry can also be expanded to other layered materials and systems. PMID:24737164

Mosby, Brian M; Díaz, Agustín; Clearfield, Abraham

2014-07-21

133

Observation of bulk strain solitons in layered bars of different materials  

Science.gov (United States)

It is shown that the behavior of a bulk strain soliton in layered waveguides, comprising layers of different materials, depends on the type of contact between layers. In delaminated waveguides, solitons propagate independently in each layer and possess significantly different velocities and amplitudes that depend on the parameters of layer materials, whereas a single resultant soliton propagates in a waveguide bonded with a glassy adhesive. These properties of nonlinear bulk strain waves can be used for nondestructive testing due to the negligibly small damping of bulk solitons.

Dreiden, G. V.; Samsonov, A. M.; Semenova, I. V.

2014-12-01

134

Unusually stable ~100-fold reversible and instantaneous swelling of inorganic layered materials.  

Science.gov (United States)

Cells can swell or shrink in certain solutions; however, no equivalent activity has been observed in inorganic materials. Although lamellar materials exhibit increased volume with increase in the lamellar period, the interlamellar expansion is usually limited to a few nanometres, with a simultaneous partial or complete exfoliation into individual atomic layers. Here we demonstrate a large monolithic crystalline swelling of layered materials. The gallery spacing can be instantly increased ~100-fold in one direction to ~90 nm, with the neighbouring layers separated primarily by H2O. The layers remain strongly held without peeling or translational shifts, maintaining a nearly perfect three-dimensional lattice structure of >3,000 layers. First-principle calculations yield a long-range directional structuring of the H2O molecules that may help to stabilize the highly swollen structure. The crystals can also instantaneously shrink back to their original sizes. These findings provide a benchmark for understanding the exfoliating layered materials. PMID:23535653

Geng, Fengxia; Ma, Renzhi; Nakamura, Akira; Akatsuka, Kosho; Ebina, Yasuo; Yamauchi, Yusuke; Miyamoto, Nobuyoshi; Tateyama, Yoshitaka; Sasaki, Takayoshi

2013-01-01

135

Zn's role in dissolution of al sacrificial anodes  

Science.gov (United States)

The role of alloying elements in the dissolution of aluminium sacrificial anodes was investigated. The effect of indium on the electrochemical performance of anode and the relationship between indium and impurities, such as silicon and iron, were studied. The distribution of indium in aluminium alloy was detected. The electrochemical behaviour of In-implanted aluminium alloy was also studied. The experimental results indicate that indium activates the surface of aluminium alloy and improves the electrochemical performance of alloy containing more amounts of impurity. Indium combines with silicon and iron. More satisfactory properties were obtained when the alloy's proportion of content of In to that of (Si+Fe) is about 1?(8˜10). The electrochemical properties of Al alloy, especially the surface activity of the anode were improved by ion implantation. Indium segregates in the alloy. The amount of Si and Fe in the In-rich segregated phase is richer than that in the matrix. It is proposed that the In-rich segregated phase particles activate the surface and promote the dissolution process of the aluminium sacrificial anode.

Sun, Hejian; Huo, Shizhong

1990-12-01

136

Protective nitrided layers for the structural materials of thermonuclear reactors  

Energy Technology Data Exchange (ETDEWEB)

Application of protective coatings based on light elements having strong interatomic bonds is one of the most practical and promising methods of decreasing the rate of erosion (wear) of the first wall of thermonuclear reactors due to ion sputtering and blistering. We carried out experiments for determining the surface radiation resistance and hydrogen permeability of a steel having a protective nitrided layer. In order to develop the protective layer on the 08Kh18N10T steel, it was subjected to nitriding in a stream of high purity nitrogen at 1000/sup 0/C. The specimens having a nitride layer were bombarded simultaneously with helium and hydrogen ions; besides this, hydrogen permeability of the specimens having a zone of internal nitriding was studied.

Afrikanov, I.N.; Baranova, E.K.; Guseva, M.I.; Isakov, M.G.; Shiryaev, P.P.

1987-07-01

137

Surface alloys as interfacial layers between quasicrystalline and periodic materials  

International Nuclear Information System (INIS)

Low adhesion with normal metals is an intrinsic property of many quasicrystalline surfaces. Although this property could be useful to develop low friction or non-stick coatings, it is also responsible for the poor adhesion of quasicrystalline coatings on metal substrates. Here we investigate the possibility of using complex metallic surface alloys as interface layers to enhance the adhesion between quasicrystals and simple metal substrates. We first review some examples where such complex phases are formed as an overlayer. Then we study the formation of such surface alloys in a controlled way by annealing a thin film deposited on a quasicrystalline substrate. We demonstrate that a coherent buffer layer consisting of the ?-Al4Cu9 approximant can be grown between pure Al and the i-Al-Cu-Fe quasicrystal. The interfacial relationships between the different layers are defined by [111]Al parallel [110]Al4Cu9 parallel [5f]i-Al-Cu-Fe

138

Formation of nanocrystalline surface layers in various metallic materials by near surface severe plastic deformation  

Digital Repository Infrastructure Vision for European Research (DRIVER)

The surface of the various kinds of metallic materials sheets were severely deformed by wire-brushing at ambient temperature to achieve nanocrystalline surface layer. The surface layers of the metallic materials developed by the near surface severe plastic deformation (NS-SPD) were characterized by means of TEM. Nearly equiaxed nanocrystals with grain sizes ranging from 30 to 200 nm were observed in the near surface regions of all the severely scratched metallic materials, which are Ti-added ...

Masahide Sato, Nobuhiro Tsuji

2004-01-01

139

Unusually stable ~100-fold reversible and instantaneous swelling of inorganic layered materials  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Cells can swell or shrink in certain solutions; however, no equivalent activity has been observed in inorganic materials. Although lamellar materials exhibit increased volume with increase in the lamellar period, the interlamellar expansion is usually limited to a few nanometres, with a simultaneous partial or complete exfoliation into individual atomic layers. Here we demonstrate a large monolithic crystalline swelling of layered materials. The gallery spacing can be instantly increased ~100...

Geng, Fengxia; Ma, Renzhi; Nakamura, Akira; Akatsuka, Kosho; Ebina, Yasuo; Yamauchi, Yusuke; Miyamoto, Nobuyoshi; Tateyama, Yoshitaka; Sasaki, Takayoshi

2013-01-01

140

UV nanoimprint materials: Surface energies, residual layers, and imprint quality  

Digital Repository Infrastructure Vision for European Research (DRIVER)

UV nanoimprint lithography is attracting more and more interest, because it has the potential of becoming a high-resolution, low-cost patterning technique. The availability of suitable UV curing materials is mandatory for successful imprinting. Within this work, a systematic investigation of commercially available photo curing materials was conducted to provide an overview of the properties of these materials. Their wetting behavior with respect to different substrate surfaces was characteriz...

Schmitt, H.; Frey, L.; Ryssel, H.; Rommel, M.; Lehrer, C.

2007-01-01

 
 
 
 
141

High Pressure Synthesis and Characterisation of Layered Carbon Nitride Materials  

Digital Repository Infrastructure Vision for European Research (DRIVER)

The research undertaken in this project has involved the synthesis of the carbon nitride material C6N9H3.HCl under high pressures and temperatures in the piston cylinder apparatus. The synthesis conditions of the material have been perfected and the relatively well crystallised products have been characterised in several ways to try to gain a better understanding of the structure of the material. Characterisation techniques used include; elemental analysis, X-ray diffraction, infrared spectro...

Lees, V. J.

2012-01-01

142

Features of heat treatment of highly porous layered materials ??????????? ???????? ????????? ???????? ?????????????? ??????????  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Effectiveness of thermal insulation products is determined by a set of criteria that can be expressed in terms of energy costs: reduction of the cost of heating (the main criterion), energy consumption in the course of construction, energy consumption in the course of production of materials having pre-set properties, and service durability of the material.On the one hand, service durability (as a property) is generated in the course of material production, and on the other hand, it depends o...

Zhukov Aleksey Dmitrievich; Smirnova Tat’yana Viktorovna; Chugunkov Aleksandr Viktorovich; Khimich Anastasiya Olegovna

2013-01-01

143

Interaction between a compliant material and an unstable boundary layer flow  

International Nuclear Information System (INIS)

The response of a compliant coating to pressure fluctuations due to an unsteady boundary layer flow and the effect of the response on the stability of the flow field are examined. A pseudospectral solution of the Navier--Stokes equations is coupled to a finite element calculation of the behavior of the compliant material. In particular, the effect of material response on the growth rate of a Tollmien--Schlichting type instability in an unstable boundary layer is examined. Results are presented for three materials; a soft polyvinylchloride (PVC), a stiffer PVC, and a two-layer material consisting of a thick layer of soft PVC covered by a thin layer of neoprene. copyright 1988 Academic Press, Inc

144

Mott p-n junctions in layered materials  

Science.gov (United States)

The p-n junction has provided the basis for the semiconductor-device industry. Investigations of p-n junctions based on Mott insulators is still in its infancy. Layered Mott insulators, such as cuprates or other transition metal oxides, present a special challenge since strong in-plane correlations are important. Here we model the planes carefully using plaquette cellular dynamical mean field theory with an exact diagonalization solver. The energy associated with interplane hopping is neglected compared with the long-range Coulomb interaction that we treat in the Hartree-Fock approximation. Within this new approach, dynamical layer theory, the charge redistribution is obtained at the final step from minimization of a function of the layer fillings. A simple analytical description of the solution, in the spirit of the Thomas-Fermi theory, reproduces quite accurately the numerical results. Various interesting charge reconstructions can be obtained by varying the Fermi energy differences between both sides of the junction. One can even obtain quasi-two-dimensional charge carriers at the interface, in the middle of a Mott insulating layer. The density of states as a function of position does not follow the simple band bending picture of semiconductors.

Charlebois, M.; Hassan, S. R.; Karan, R.; Sénéchal, D.; Tremblay, A.-M. S.

2013-01-01

145

Effect of outer layer thickness on full concentration gradient layered cathode material for lithium-ion batteries  

Science.gov (United States)

Full concentration gradient (FCG) layered cathode materials Li[Ni0.6-xCo0.15+xMn0.25]O2 (x = 0, 0.01, and 0.04) with different outer layer thicknesses are synthesized via a specially developed coprecipitation method. In the FCG cathode, the nickel concentration decreases linearly and the cobalt concentration increases from the center to particle surface throughout the particle at a fixed composition of Mn. The thickness of the FCG primary particle increases in the radial direction with an increasing outer layer thickness of the secondary particles and significantly affects the electrochemical performance. An increase in the stable outer layer thickness improves the cycle performance and thermal stability of the FCG materials at the expense of reversible capacity, whereas the rate capability and low temperature performance are significantly deteriorated by increasing outer layer thickness. All of the FCG materials exhibit superior electrochemical and thermal properties compared to the conventional cathode Li[Ni0.58Co0.17Mn0.25]O2 due to the unique microstructure of the FCG cathode.

Lee, Eung-Ju; Noh, Hyung-Joo; Yoon, Chong S.; Sun, Yang-Kook

2015-01-01

146

TiO?/ZnO inner/outer double-layer hollow fibers for improved detection of reducing gases.  

Science.gov (United States)

TiO2/ZnO double-layer hollow fibers (DLHFs) are proposed as a superior sensor material in comparison to regular single-layer hollow fibers (HFs) for the detection of reducing gases. DLHFs were synthesized on sacrificial polymer fibers via atomic layer deposition of a first layer of TiO2 followed by a second layer of ZnO and by a final thermal treatment. The inner TiO2 receives electrons from the ZnO outer layer, which becomes more resistive due to the significant loss of electrons. This highly resistive ZnO layer partially regains its original resistivity when exposed to reducing gases such as CO, thus enabling more resistance variation in DLHFs. DLHFs are a novel material compared to HFs and can be successfully employed to fabricate chemical sensors for the accurate detection of reducing gases. PMID:25379680

Katoch, Akash; Kim, Jae-Hun; Kim, Sang Sub

2014-12-10

147

Neutron scatering and lattice dynamics of materials with layered structures  

International Nuclear Information System (INIS)

A brief summary of fundamental equations for the Born-von Karman formalism is presented. A force model is then constructed in which certain parameters are used to characterize the interatomic interactions. The inelastic scattering of neutrons has proved to be an invaluable experimental technique for studying in detail, the dynamics of crystalline solids and a brief summary of the main results which are used in the interpretation of experimental data is presented. Atomic vibrations in layered compounds are fully discussed and neutron scattering experiments on layered compounds outlined. Experimental data, with some emphasis on experimental details, are presented for graphite, transition metal dichalcogenides, GaSe, PbI2 and iodine. (C.F.)

148

"Determination of mechanical strength of different material double-layer rectangular tablets "  

Directory of Open Access Journals (Sweden)

Full Text Available The mechanical strength of different material composite beams were assessed. All tablets were subjected to three-point bending test. For the preparation of tablets, the material of the lower layer was initially put in the die and compacted by a certain pressure. The second material was then put upon the first layer. Modulus of elasticity of the selected materials were used to interpret the behaviour of the top and bottom layers of the different materials composite tablets. Determination of the strength at the highest and lowest point of different material composite beams, showed that if the material with higher modulus of elasticity was placed at the lower layer, the value of compressive strength (?c obtained from exerting fracture load at the higher point, was more than the value obtained at the lower point (i.e. tensile strength, ?f. On the other hand, if the material of higher modulus of elasticity E, was located at the top surface, the stress value at the lower layer (?f was more than its value at the higher layer (i.e. ?c. The range of ?c/?f was 1/3, if number of components (n was much more than one. Inversely, when ‘n’ was less than 1, the value for ?c/?f was near 3.

"Haririan I

2000-08-01

149

Optical tamm states at interfaces of different periodic media containing single and double negative material layers  

International Nuclear Information System (INIS)

Optical Tamm States (OTS) are investigated at the interfaces of semi-infinite metal and finite one dimensional periodic structures. Three types of periodic structures are considered here. Initially a one dimensional structure of alternate regular material layers is considered. The other two structures consist of alternate left-handed material and regular material layers and alternate single negative layers. The transfer matrix approach is used to derive the dispersion relation for the TE mode Optical Tamm States (OTS). The dispersion relations is plotted in the photonic band gap frequency range and analyzed by changing the structure parameters. (author)

150

Surface alloys as interfacial layers between quasicrystalline and periodic materials  

Energy Technology Data Exchange (ETDEWEB)

Low adhesion with normal metals is an intrinsic property of many quasicrystalline surfaces. Although this property could be useful to develop low friction or non-stick coatings, it is also responsible for the poor adhesion of quasicrystalline coatings on metal substrates. Here we investigate the possibility of using complex metallic surface alloys as interface layers to enhance the adhesion between quasicrystals and simple metal substrates. We first review some examples where such complex phases are formed as an overlayer. Then we study the formation of such surface alloys in a controlled way by annealing a thin film deposited on a quasicrystalline substrate. We demonstrate that a coherent buffer layer consisting of the {gamma}-Al{sub 4}Cu{sub 9} approximant can be grown between pure Al and the i-Al-Cu-Fe quasicrystal. The interfacial relationships between the different layers are defined by [111]{sub Al} parallel [110]{sub Al4Cu9} parallel [5f]{sub i-Al-}C{sub u-Fe}.

Duguet, T; Ledieu, J; Dubois, J M; Fournee, V [Laboratoire de Science et Genie des Materiaux et de Metallurgie, UMR 7584 CNRS-Nancy Universite, Ecole des Mines de Nancy, Parc de Saurupt, F-54042 Nancy (France)], E-mail: fournee@lsg2m.org

2008-08-06

151

A estrutura sacrificial do compadrio: uma ontologia da desigualdade?  

Directory of Open Access Journals (Sweden)

It is shown that god-parenthood is not only a religious or kinship institution and that it does not reinforce inequalities that supposedly pre-exist it, but rather it is a structure that generates inequalities. God-parenthood is understood as a structure by the description of reciprocity circuits. Understood as the circulation of a child from biological towards spiritual parents, to be returned by "grace", it implies asymmetries and inequalities. It also evokes the ontology of the social, founded on non-mercantile values' circulation, and on what Sahlins (2008 designates "elementary structure of political life". It is shown that reciprocity is related to the sacrificial aspect of the child's gift, and also to other types of considerations, such as that present in the catholic vows. Finally, it is demonstrated the relevancy of this type of analysis for future understandings of other benefits and categories often taken as purely economic ones, such as "labor".

Marcos Lanna

2009-01-01

152

Zinc-stearate-layered hydroxide nanohybrid material as a precursor to produce carbon nanoparticles  

Energy Technology Data Exchange (ETDEWEB)

Research highlights: > In this work, a new organic-clay nanohybrid material, in which the organic moiety is intercalated between the inorganic layers, was synthesized using stearate anion as a guest and zinc hydroxide nitrate as an inorganic layered host by ion-exchange technique. Carbon nanoparticles were obtained by heat treating of the nanohybrid material, zinc-stearate-layered hydroxide. The proposed method is very simple, the chemicals used in the synthesis are cheap and the manner is economic and suitable for a large scale production of nano-sized carbon nanoparticles. - Abstract: Zinc-stearate-layered hydroxide nanohybrid was prepared using stearate anion as an organic guest, and zinc layered hydroxide nitrate, as a layered inorganic host by the ion-exchange method. Powder X-ray diffraction patterns and Fourier transform infrared results indicated that the stearate anion was actually intercalated into the interlayer of zinc layered hydroxide nitrate and confirmed the formation of the host-guest nanohybrid material. Also, surface properties data showed that the intercalation process has changed the porosity for the as-prepared nanohybrid material in comparison with that of the parent material, zinc hydroxide nitrate. The nanohybrid material was heat-treated at 600 deg. C under argon atmosphere. Stearate anion was chosen as a carbonaceous reservoir in the nanohybrid to produce carbon nanoparticles after heat-treating of the nanohybrid and subsequently acid washing process.

Ghotbi, Mohammad Yeganeh, E-mail: myeganeh@malayeru.ac.ir [Nanomaterials and Nanotechnology Program, Ceramic Engineering Department, Faculty of Engineering, University of Malayer, Malayer (Iran, Islamic Republic of); Materials and Energy Research Center, P.O. Box 14155-4777, Tehran (Iran, Islamic Republic of); Bagheri, Narjes [Materials and Energy Research Center, P.O. Box 14155-4777, Tehran (Iran, Islamic Republic of); Sadrnezhaad, S.K. [Materials and Energy Research Center, P.O. Box 14155-4777, Tehran (Iran, Islamic Republic of); Department of Materials Sciences and Engineering, Sharif University of Technology, P.O. Box 11365-9466, Tehran (Iran, Islamic Republic of)

2011-02-03

153

Zinc-stearate-layered hydroxide nanohybrid material as a precursor to produce carbon nanoparticles  

International Nuclear Information System (INIS)

Research highlights: ? In this work, a new organic-clay nanohybrid material, in which the organic moiety is intercalated between the inorganic layers, was synthesized using stearate anion as a guest and zinc hydroxide nitrate as an inorganic layered host by ion-exchange technique. Carbon nanoparticles were obtained by heat treating of the nanohybrid material, zinc-stearate-layered hydroxide. The proposed method is very simple, the chemicals used in the synthesis are cheap and the manner is economic and suitable for a large scale production of nano-sized carbon nanoparticles. - Abstract: Zinc-stearate-layered hydroxide nanohybrid was prepared using stearate anion as an organic guest, and zinc layered hydroxide nitrate, as a layered inorganic host by the ion-exchange method. Powder X-ray diffraction patterns and Fourier transform infrared results indicated that the stearate anion was actually intercalated into the interlayer of zinc layered hydroxide nitrate and confirmed the formation of the host-guest nanohybrid material. Also, surface properties data showed that the intercalation process has changed the porosity for the as-prepared nanohybrid material in comparison with that of the parent material, zinc hydroxide nitrate. The nanohybrid material was heat-treated at 600 deg. C under argon atmosphere. Stearate anion was chosen as a carbonaceous reservoir in the nanohybrid to produce carbon nanoparticles after heat-treating of the nanohybrid and subsequently acid washhe nanohybrid and subsequently acid washing process.

154

Structural material having surface treated layer and method of forming the surface treated layer  

Energy Technology Data Exchange (ETDEWEB)

Energy is injected to the surface of structural members in a nuclear reactor made of an austenite stainless steel by using laser beams to melt the surface. Then, the surface is solidified by in pro-eutectoid ferrite which is formed under a condition of relatively low cooling rate to form a solidified portion comprising two-phase tissue of ferrite and austenite. Then, the surface of the surface layer of the two-phase tissue is melted using laser beams. Then, a solidified portion of an austenite single phase tissue which is formed under a condition of high cooling rate is formed. Thus, an upper layer made of an single phase austenite tissue and a lower layer comprising two-phase tissue of ferrite and austenite are formed. With such a constitution, a structure less sensitive to coagulation cracking and high temperature cracking during surface treatment and having excellent corrosion resistance can be obtained. (I.N.)

Uraki, Keiichi; Satsuta, Toshitaka; Konuma, Akira [and others

1996-04-23

155

Structural material having surface treated layer and method of forming the surface treated layer  

International Nuclear Information System (INIS)

Energy is injected to the surface of structural members in a nuclear reactor made of an austenite stainless steel by using laser beams to melt the surface. Then, the surface is solidified by in pro-eutectoid ferrite which is formed under a condition of relatively low cooling rate to form a solidified portion comprising two-phase tissue of ferrite and austenite. Then, the surface of the surface layer of the two-phase tissue is melted using laser beams. Then, a solidified portion of an austenite single phase tissue which is formed under a condition of high cooling rate is formed. Thus, an upper layer made of an single phase austenite tissue and a lower layer comprising two-phase tissue of ferrite and austenite are formed. With such a constitution, a structure less sensitive to coagulation cracking and high temperature cracking during surface treatment and having excellent corrosion resistance can be obtained. (I.N.)

156

High quality 2D crystals made by anodic bonding: a general technique for layered materials  

International Nuclear Information System (INIS)

Anodic bonding of nanolayers is an easy technique based on a simple apparatus, which has already proven successful in application in the fabrication of high quality graphene. Here we demonstrate its extension to the fabrication of high quality nanolayers from several layered materials. The strengths of this technique are its high throughput rate and ease of application. All fabrication parameters are controllable and need to be determined carefully. We report optimal parameters found for nine layered materials. In general, using optimal parameters results in high quality 2D layers, in most cases much larger than those obtained by ‘Scotch tape’ microcleavage, with higher yields and which are easily transferable to other substrates. Moreover the samples obtained are clean and the good optical contrast of these layers on the glass substrate makes their identification very easy. This is thus the technique of choice for making nanolayers in the laboratory from any layered material. (paper)

157

Theoretical Studies on Layered Materials and Transition Metal Borides  

Science.gov (United States)

From a geometrical point of view, a crystal structure may be described in terms of coordination polyhedra. The number of vertices of polyhedra, the coordination number, depends largely on the cation to anion radius ratio. It is obvious that a minimum coordination number is necessary for the formation of a layer structure. With a coordination number 2, only chain or finite molecules are possible. A high coordination number, on the other hand, will lead to a two, three dimensional or framework structure. We have studied several compounds which belong to the group of structures mentioned above. rm V_2O_5, Bi_2WO_6, LiBiPd_2O_4, Pd_3P_2S _8 and CuTe, have a two-dimensional layered structures whereas the hexagonal rm MT_3B _2 (M = rare earth metal or Ca, Sr, Ba. T = Fe, Ru, Os, Co, Rh, Ir, Pt) compounds and rm MT_4B_4(M = rare earth metal. T = Ru, Os, Co, Rh, Ir) are three dimensional expansions of polyhedra. Inside of these solid state crystals, electrons and atoms act collectively to create waves described as quasiparticles. They determine in part whether a crystal is an insulator, a semiconductor, a conductor or a superconductor. In analyzing the electronic structure and properties of our target compounds, we focus our study on structural distortions. These studies include the inter-layer interaction in a number of systems and the bonding and dynamics of transition metal boride superconductors. We rely heavily upon the LCAO approach of the chemist and the tight binding approach of solid state physicist.

Seong, Seeyearl

158

Atomic layer deposition on polymer based flexible packaging materials: Growth characteristics and diffusion barrier properties  

Energy Technology Data Exchange (ETDEWEB)

One of the most promising areas for the industrial application of atomic layer deposition (ALD) is for gas barrier layers on polymers. In this work, a packaging material system with improved diffusion barrier properties has been developed and studied by applying ALD on flexible polymer based packaging materials. Nanometer scale metal oxide films have been applied to polymer-coated papers and their diffusion barrier properties have been studied by means of water vapor and oxygen transmission rates. The materials for the study were constructed in two stages: the paper was firstly extrusion coated with polymer film, which was then followed by the ALD deposition of oxide layer. The polymers used as extrusion coatings were polypropylene, low and high density polyethylene, polylactide and polyethylene terephthalate. Water vapor transmission rates (WVTRs) were measured according to method SCAN-P 22:68 and oxygen transmission rates (O{sub 2}TRs) according to a standard ASTM D 3985. According to the results a 10 nm oxide layer already decreased the oxygen transmission by a factor of 10 compared to uncoated material. WVTR with 40 nm ALD layer was better than the level currently required for most common dry flexible packaging applications. When the oxide layer thickness was increased to 100 nm and above, the measured WVTRs were limited by the measurement set up. Using an ALD layer allowed the polymer thickness on flexible packaging materials to be reduced. Once the ALD layer was 40 nm thick, WVTRs and O{sub 2}TRs were no longer dependent on polymer layer thickness. Thus, nanometer scale ALD oxide layers have shown their feasibility as high quality diffusion barriers on flexible packaging materials.

Kaeaeriaeinen, Tommi O., E-mail: tommi.kaariainen@lut.f [ASTRaL, Lappeenranta University of Technology, Prikaatinkatu 3 E, 50100 Mikkeli (Finland); Maydannik, Philipp, E-mail: philipp.maydannik@lut.f [ASTRaL, Lappeenranta University of Technology, Prikaatinkatu 3 E, 50100 Mikkeli (Finland); Cameron, David C., E-mail: david.cameron@lut.f [ASTRaL, Lappeenranta University of Technology, Prikaatinkatu 3 E, 50100 Mikkeli (Finland); Lahtinen, Kimmo, E-mail: kimmo.lahtinen@tut.f [Tampere University of Technology, Paper Converting and Packaging Technology, P.O. Box 541, 33101 Tampere (Finland); Johansson, Petri, E-mail: petri.johansson@tut.f [Tampere University of Technology, Paper Converting and Packaging Technology, P.O. Box 541, 33101 Tampere (Finland); Kuusipalo, Jurkka, E-mail: jurkka.kuusipalo@tut.f [Tampere University of Technology, Paper Converting and Packaging Technology, P.O. Box 541, 33101 Tampere (Finland)

2011-03-01

159

Layered packaging: A synergistic method of transporting radioactive material  

International Nuclear Information System (INIS)

The DOE certification for a transportation cask used to ship radioactive Krypton 85 from the Idaho Chemical Processing Plant (ICPP) to Oak Ridge National Laboratory (ORNL), was allowed to expire in 1987. The Westinghouse Idaho Nuclear Company (WINCO) was charged by DOE with modifying this cask to meet all current NRC requirements and preparing an updated Safety Analysis Report for Packaging, which would be submitted by DOE to the NRC for certification. However, an urgent need arose for ORNL to receive Krypton 85 which was in storage at the ICPP, which would not allow time to obtain certification of the modified shipping cask. WINCO elected to use a layered shipping configuration in which the gaseous Krypton 85 was placed in the uncertified, modified shipping cask to make use of its shielding and thermal insulation properties. This cask was then inserted into the Model No. 6400 (Super Tiger) packaging using a specially constructed plywood box and polyurethane foam dunnage. Structural evaluations were completed to assure the Super Tiger would provide the necessary impact, puncture, and thermal protection during maximum credible accidents. Analyses were also completed to determine the uncertified Krypton shipping cask would provide the necessary containment and shielding for up to 3.7 E+14 Bq of Krypton 85 when packaged inside the Super Tiger. The resulting reports, based upon this layered packaging concept, were adequate to first obtain DOE certification for several rest obtain DOE certification for several restricted shipments of Krypton 85 and then NRC certification for unrestricted shipments

160

Computational synthesis of single-layer GaN on refractory materials  

Science.gov (United States)

The synthesis of single-layer materials relies on suitable substrates. In this paper, we identify suitable substrates for the stabilization and growth of single-layer GaN and characterize the effect of the substrate on the electronic structure of single-layer GaN. We identify two classes of epitaxial substrates, refractory metal diborides and transition-metal dichalcogenides. We find that the refractory diborides provide epitaxial stabilization for the growth and functionalization of single layer GaN. We show that chemical interactions of single layer GaN with the diboride substrates result in n-type doping of the single-layer GaN. Transition-metal dichalcogenides, on the other hand, although epitaxially matched, cannot provide sufficient thermodynamic stabilization for the growth of single layer GaN. Nonetheless, energy band alignments of GaN/metal chalcogenides show that they make good candidates for heterostructures.

Singh, Arunima K.; Hennig, Richard G.

2014-08-01

 
 
 
 
161

Can nature's design be improved upon? High strength, transparent nacre-like nanocomposites with double network of sacrificial cross links.  

Science.gov (United States)

The preparation of a high-strength and highly transparent nacre-like nanocomposite via layer-by-layer assembly technique from poly(vinyl alcohol) (PVA) and Na+-montmorillonite clay nanosheets is reported in this article. We show that a high density of weak bonding interactions between the polymer and the clay particles: hydrogen, dipole-induced dipole, and van der Waals undergoing break-reform deformations, can lead to high strength nanocomposites: sigmaUTS approximately 150 MPa and E' approximately 13 GPa. Further introduction of ionic bonds into the polymeric matrix creates a double network of sacrificial bonds which dramatically increases the mechanical properties: sigmaUTS approximately 320 MPa and E' approximately 60 GPa. PMID:18590319

Podsiadlo, Paul; Kaushik, Amit K; Shim, Bong Sup; Agarwal, Ashish; Tang, Zhiyong; Waas, Anthony M; Arruda, Ellen M; Kotov, Nicholas A

2008-11-20

162

Radionuclide separations using pillared layered materials. Final report  

International Nuclear Information System (INIS)

The objective of this project is to prepare an all inorganic strontium specific sorbent or ion exchanger for the removal of highly alkaline nuclear waste solutions. A series of clays and layered titanates were pillared and calcined to convert their essentially two dimensional structure to three dimensional porous structures with high surface areas. The pillaring agents were alumina, zirconia, chromia and silica based. The pillared clays, particularly those containing Zr pillars, achieved moderate (Kd as high at 13,700 ml/g with V:m = 28) selectivities for Sr2+. In contrast, the silica pillared titanates showed exceptional affinities for Sr2+ with Kd values in excess of 100,000 ml/g in 5M NaNO3 + 1M NaOH. These latter results suggest a more detailed study of the pillared titanates in the presence of simulants closely resembling real waste solutions

163

Self-organized electronic superlattices in layered materials  

Science.gov (United States)

We show that in layered systems with electronic phase separation tendency, the long-range Coulomb interaction can drive the spontaneous formation of unidirectional superlattices of electronic charge in a completely homogeneous crystalline background. In this self-organized electronic heterostructure, the ratio among the number of crystalline planes in the minority and majority electronic phases corresponds to Farey fractions with the superlattice period controlled by the background charge density and the frustrating Coulomb interaction strength. The phase diagram displays Arnold tongues obeying a modified Farey tree hierarchy and a devil's staircase, typical of systems with frustration among different scales. We further discuss the competition of these electronic superlattices, recently observed in iron-based superconductors and mixed valence compounds, with in-plane electronically modulated phases.

Ortix, Carmine; Di Castro, Carlo; Lorenzana, José

2014-12-01

164

Radionuclide separations using pillared layered materials. Final report  

Energy Technology Data Exchange (ETDEWEB)

The objective of this project is to prepare an all inorganic strontium specific sorbent or ion exchanger for the removal of highly alkaline nuclear waste solutions. A series of clays and layered titanates were pillared and calcined to convert their essentially two dimensional structure to three dimensional porous structures with high surface areas. The pillaring agents were alumina, zirconia, chromia and silica based. The pillared clays, particularly those containing Zr pillars, achieved moderate (Kd as high at 13,700 ml/g with V:m = 28) selectivities for Sr{sup 2+}. In contrast, the silica pillared titanates showed exceptional affinities for Sr{sup 2+} with Kd values in excess of 100,000 ml/g in 5M NaNO{sup 3} + 1M NaOH. These latter results suggest a more detailed study of the pillared titanates in the presence of simulants closely resembling real waste solutions.

Clearfield, A. [Texas A and M Univ., College Station, TX (United States). Research Foundation

1995-08-31

165

Crack propagation in bone on the scale of mineralized collagen fibrils: role of polymers with sacrificial bonds and hidden length.  

Science.gov (United States)

Sacrificial bonds and hidden length (SBHL) in structural molecules provide a mechanism for energy dissipation at the nanoscale. It is hypothesized that their presence leads to greater fracture toughness than what is observed in materials without such features. Here, we investigate this hypothesis using a simplified model of a mineralized collagen fibril sliding on a polymeric interface with SBHL systems. A 1D coarse-grained nonlinear spring-mass system is used to model the fibril. Rate-and-displacement constitutive equations are used to describe the mechanical properties of the polymeric system. The model quantifies how the interface toughness increases as a function of polymer density and number of sacrificial bonds. Other characteristics of the SBHL system, such as the length of hidden loops and the strength of the bonds, are found to influence the results. The model also gives insight into the variations in the mechanical behavior in response to physiological changes, such as the degree of mineralization of the collagen fibril and polymer density in the interfibrillar matrix. The model results provide constraints relevant for bio-mimetic material design and multiscale modeling of fracture in human bone. PMID:25108082

Wang, Wenyi; Elbanna, Ahmed

2014-11-01

166

Steady-state Rn diffusion through tailings and multiple layers of covering materials  

International Nuclear Information System (INIS)

Uranium tailings piles are generally rehabilitated by covering them with a number of layers of earthen materials. This paper derives exact equations for the Rn concentration profile and flux attenuation through any number of covering layers. The equations take account of the distribution of Rn between interstitial air and water. Numerical examples are given to show that approximate methods give rise to significant errors in some circumstances. The flux attenuation factor depends not only on the diffusion coefficient, porosity, moisture content and thickness of each layer but also upon the order of placement. To achieve maximum flux attenuation, the least permeable material should be uppermost

167

Proactive materials aging management and multi-layered maintenance  

International Nuclear Information System (INIS)

Long term operation of NPP has been receiving a great concern based upon the plant operation experiences and progressive improvement in countermeasures and mitigations. At the same time of this LTO movement, proactive materials aging management is also receiving a great concern to realize the LTO in NPP. Recent PMDM activities in Japan as well as some international one are reviewed and a necessity of an international cooperation is emphasized in relation to reliable maintenance performance connected from the top of the organization to operators and maintenance engineers at plant sites. (author)

168

High Curie temperature drive layer materials for ion-implanted magnetic bubble devices  

Science.gov (United States)

Ion implantation of bubble garnets can lower the Curie temperature by 70 C or more, thus limiting high temperature operation of devices with ion-implanted propagation patterns. Therefore, double-layer materials were made with a conventional 2-micron bubble storage layer capped by an ion-implantable drive layer of high Curie temperature, high magnetostriction material. Contiguous disk test patterns were implanted with varying doses of a typical triple implant. Quality of propagation was judged by quasistatic tests on 8-micron period major and minor loops. Variations of magnetization, uniaxial anisotropy, implant dose, and magnetostriction were investigated to ensure optimum flux matching, good charged wall coupling, and wide operating margins. The most successful drive layer compositions were in the systems (SmDyLuCa)3(FeSi)5O12 and (BiGdTmCa)3(FeSi)5O12 and had Curie temperatures 25-44 C higher than the storage layers.

Fratello, V. J.; Wolfe, R.; Blank, S. L.; Nelson, T. J.

1984-01-01

169

High Curie temperature drive layer materials for ion-implanted magnetic bubble devices  

Science.gov (United States)

Ion implantation of bubble garnets can lower the Curie temperature by 70 C or more, thus limiting high temperature operation of devices with ion-implanted propagation patterns. Therefore, double-layer materials were made with a conventional 2-micron bubble storage layer capped by an ion-implantable drive layer of high Curie temperature, high magnetostriction material. Contiguous disk test patterns were implanted with varying doses of a typical triple implant. Quality of propagation was judged by quasistatic tests on 8-micron period major and minor loops. Variations of magnetization, uniaxial anisotropy, implant dose, and magnetostriction were investigated to ensure optimum flux matching, good charged wall coupling, and wide operating margins. The most successful drive layer compositions were in the systems (SmDyLuCa)3(FeSi)5O12 and (BiGdTmCa)3(FeSi)5O12 and had Curie temperatures 25-44 C higher than the storage layers.

Fratello, V. J.; Wolfe, R.; Blank, S. L.; Nelson, T. J.

1984-03-01

170

Optimized cylindrical invisibility cloak with minimum layers of non-magnetic isotropic materials  

International Nuclear Information System (INIS)

We present optimized design of cylindrical invisibility cloak with minimum layers of non-magnetic isotropic materials. Through an optimization procedure based on genetic algorithm, simpler cloak structure and more realizable material parameters can be achieved with better cloak performance than that of an ideal non-magnetic cloak with a reduced set of parameters. We demonstrate that a cloak shell with only five layers of two normal materials can result in an average 20 dB reduction in the scattering width for all directions when covering the inner conducting cylinder with the cloak. The optimized design can substantially simplify the realization of the invisibility cloak, especially in the optical range.

171

Suitability of Structural Aluminium Profiles as Sacrificial Anode for Carbon Steel  

Digital Repository Infrastructure Vision for European Research (DRIVER)

The life of low carbon steels in many small scale structures can be remarkably prolonged by complementary sacrificial anode cathodic protection (SACP) but for constraints in availability of specialty anodes. Suitability of commonly available structural aluminium profiles as sacrificial anodes for low carbon steel has been investigated. Three different profiles were studied. Bare and coated steel samples were found to migrate clearly too cathodic potential regimes when coupled with the press-f...

Otunniyi, Iyiola O.; Oloruntoba, Daniel T.

2012-01-01

172

Using fugacity to predict volatile emissions from layered materials with a clay/polymer diffusion barrier  

Science.gov (United States)

Structural insulated panels (SIPs) have significant environmental and energy advantages. However, the tight structure that results may cause degraded indoor air quality and the potential release of volatile organic compounds (VOCs) from these layered materials must be considered. A physically based model for predicting VOC emissions from multi-layer materials is described. Fugacity is used to eliminate the concentration discontinuities at the interface between layers. This avoids an obstacle associated with numerically simulating mass transfer in composite materials. The numerical model is verified for a double-layer system by comparing predicted concentrations to those obtained with a previously published analytical model. In addition, hexanal emissions from multi-layer SIPs are simulated to demonstrate the usefulness of the fugacity approach. Finally, the multi-layer model is used to investigate the impact that clay/polyurethane nanocomposite diffusion barriers can have on VOC emissions. Indoor gas-phase concentrations can be greatly reduced with a barrier layer on the surface, thereby minimizing the environmental impact of SIPs.

Yuan, Huali; Little, John C.; Marand, Eva; Liu, Zhe

173

Struvite precipitation and phosphorus removal using magnesium sacrificial anode.  

Science.gov (United States)

Struvite precipitation using magnesium sacrificial anode as the only source of magnesium is presented. High-purity magnesium alloy cast anode was found to be very effective in recovery of high-quality struvite from water solutions and from supernatant of fermented waste activated sludge from a wastewater treatment plant that does not practice enhanced biological phosphorus removal. Struvite purity was strongly dependent on the pH and the electric current density. Optimum pH of the 24 mM phosphorus and 46 mM ammonia solution (1:1.9 P:N ratio) was in the broad range between 7.5 and 9.3, with struvite purity exceeding 90%. Increasing the current density resulted in elevated struvite purity. No upper limits were observed in the studied current range of 0.05-0.2 A. Phosphorus removal rate was proportional to the current density and comparable for tests with water solutions and with the supernatant from fermented sludge. The highest P-removal rate achieved was 4.0 mg PO4-P cm(-2) h(-1) at electric current density of 45 A m(-2). Initial substrate concentrations affected the rate of phosphorus removal. The precipitated struvite accumulated in bulk liquid with significant portions attached to the anode surface from which regular detachment occurred. PMID:24387911

Kruk, Damian J; Elektorowicz, Maria; Oleszkiewicz, Jan A

2014-04-01

174

Optimisation of the material properties of indium tin oxide layers for use in organic photovoltaics  

Science.gov (United States)

The influence of indium tin oxide [(In2O3:Sn), ITO] material properties on the output performance of organic photovoltaic (OPV) devices has been modelled and investigated. In particular, the effect of altering carrier concentration (n), thickness (t), and mobility (?e) in ITO films and their impact on the optical performance, parasitic resistances and overall efficiency in OPVs was studied. This enables optimal values of these parameters to be calculated for solar cells made with P3HT:PC61BM and PCPDTBT:PC71BM active layers. The optimal values of n, t and ?e are not constant between different OPV active layers and depend on the absorption spectrum of the underlying active layer material system. Consequently, design rules for these optimal values as a function of donor bandgap in bulk-heterojunction active layers have been formulated.

Doggart, P.; Bristow, N.; Kettle, J.

2014-09-01

175

Optimisation of the material properties of indium tin oxide layers for use in organic photovoltaics  

International Nuclear Information System (INIS)

The influence of indium tin oxide [(In2O3:Sn), ITO] material properties on the output performance of organic photovoltaic (OPV) devices has been modelled and investigated. In particular, the effect of altering carrier concentration (n), thickness (t), and mobility (?e) in ITO films and their impact on the optical performance, parasitic resistances and overall efficiency in OPVs was studied. This enables optimal values of these parameters to be calculated for solar cells made with P3HT:PC61BM and PCPDTBT:PC71BM active layers. The optimal values of n, t and ?e are not constant between different OPV active layers and depend on the absorption spectrum of the underlying active layer material system. Consequently, design rules for these optimal values as a function of donor bandgap in bulk-heterojunction active layers have been formulated.

176

Metalorganic chemical vapor deposition of gallium nitride on sacrificial substrates  

Science.gov (United States)

GaN-based light emitting diodes (LEDs) face several challenges if the technology is to continue to make a significant impact in general illumination, and on technology that has become known as solid state lighting (SSL). Two of the most pressing challenges for the continued penetration of SSL into traditional lighting applications are efficacy and total lumens from the device, and their related cost. The development of alternative substrate technologies is a promising avenue toward addressing both of these challenges, as both GaN-based device technology and the associated metalorganic chemical vapor deposition (MOCVD) technology are already relatively mature technologies with a well-understood cost base. Zinc oxide (ZnO) and silicon (Si) are among the most promising alternative substrates for GaN epitaxy. These substrates offer the ability to access both higher efficacy and lumen devices (ZnO) at a much reduced cost. This work focuses on the development of MOCVD growth processes to yield high quality GaN-based materials and devices on both ZnO and Si. ZnO is a promising substrate for growth of low defect-density GaN because of its similar lattice constant and thermal expansion coefficient. The major hurdles for GaN growth on ZnO are the instability of the substrate in a hydrogen atmosphere, which is typical of nitride growth conditions, and the inter-diffusion of zinc and oxygen from the substrate into the GaN-based epitaxial layer. A process was developed for the MOCVD growth of GaN and InxGa 1-xN on ZnO that attempted to address these issues. The structural and optical properties of these films were studied using various techniques. X-ray diffraction (XRD) showed the growth of wurtzite GaN on ZnO, and room-temperature photoluminescence (RT-PL) showed near band-edge luminescence from the GaN and InxGa1-xN layers. However, high zinc and oxygen concentrations due to interdiffusion near the ZnO substrate remained an issue; therefore, the diffusion of zinc and oxygen into the subsequent GaN layer was studied in more detail. Several approaches were investigated---for example, transition layers such as Al2O3 and Al xGa1-xN/GaN---to minimize diffusion of these impurities into the GaN layer. Silicon, due to its prevalence, is the most promising material for the development of an inexpensive, large-area substrate technology. The challenge in MOCVD growth of GaN on Si is the tensile strain induced by the lattice and thermal mismatch between GaN and Si and the formation of anti-phase boundaries. Typical approaches to solve these problems involve complicated and multiple buffer layer structures, which lead to relatively slow growth rates. In this work, a thin atomic layer deposition (ALD)-grown Al2O3 interlayer was employed to relieve strain and increase material quality while also simplifying the growth process. While some residual strain was still observed in the GaN material by XRD and PL, the use of this oxide interlayer leads to an improvement in thin film quality as seen by a reduction in both crack density (device structures. A redshift in peak emission wavelength was also observed on silicon compared to sapphire, and this is attributed to higher indium content due to the slight tensile strain in the layers on silicon. IQE of the devices on silicon is ˜32% as measured by LT-PL, compared to ˜37% on sapphire, but this difference can be assigned to the difference in indium compositions. These results show a great promise toward an inexpensive, large-area, silicon-based substrate technology for MOCVD growth of the next generation of GaN-based optoelectronic devices for SSL and other applications.

Fenwick, William Edward

177

Surface layer properties of the workpiece material in high performance grinding  

Digital Repository Infrastructure Vision for European Research (DRIVER)

This paper focuses on the development of high temperatures in the cutting zone during high performance grinding. In order to identify the infl uence of grinding temperature on surface integrity, temperatures were measured in the workpiece surface layer under diff erent machining conditions. Beside this, under the same conditions, the surface layer properties of the workpiece material were determined through metallographic examination. Microstructureand microhardness of the workpiece surface l...

Gostimirovic?, M.; Kovac?, P.; Jes?ic?, D.; S?koric?, B.; Savkovic?, B.

2012-01-01

178

Single layer buckle folding in non-linear materials—II. Comparison between theory and experiment  

Science.gov (United States)

Results from scale-model experiments on the development of single layer folds from an initial perturbation of known shape are compared with infinitesimal amplitude theories for buckling of non-linear viscous materials. The experiments were performed in pure shear, using paraffin wax as an analogue for the power-law behaviour of common rocks. Effective viscosity ratios of 30 and 8 between layer and matrix were used, with power-law stress exponents of around 3.8 for the matrix and around 3 for the layer. The layer material shows strain softening behaviour. The variation of growth rate with wavelength (the range of wavelengths corresponding to the Fourier series representation for the non-periodic fold shape) was determined for each of the perturbation shapes and viscosity contrasts employed. These growth rate curves closely resemble those calculated from theory, but for short wavelengths and particularly for narrow initial pertubations, observed growth rates tend to be higher than theoretical values. This may reflect the strain softening behaviour of the layer. Bonding of the matrix—layer interface appears to have a much greater effect on the growth rate curve than theoretically predicted, at least for the low to moderate viscosity ratios investigated. Experimental fold shapes are also compared directly with theoretical shapes. The best-fit between theory and observation occurs for values of the viscosity ratio and the layer stress exponent which are very close to the calibrated material properties, providing further experimental evidence that current fold theories are a good approximation to low but finite amplitude, single layer folding in non-linear materials.

Mancktelow, Neil S.; Abbassi, Mohammad R.

1992-01-01

179

Crack propagation in the vicinity of the interface in layered materials  

Directory of Open Access Journals (Sweden)

Full Text Available The paper deals with the problem of crack propagation in the vicinity of the interface in layered materials. Layered materials are often used in practice, primarily because of their better mechanical properties in comparison with the properties of individual materials components. The configuration of a crack with its tip at the bi-material interface can be created during crack propagation in the structure. It is important to decide if the crack propagates into the second material in this case. The step change of material properties at the bi-material interface means that classical linear elastic fracture mechanics are not appropriate. A generalized approach has to be applied. In this paper, two criteria are applied for the determination of the critical value of an applied load. Knowledge of these values is important for the estimation of the service life time of such structures. The results obtained can be used especially for multi-layer polymer composites designs. On the basis of the procedures presented, suitable materials combinations can be suggested for new composite structures.

Knésl Z.

2009-06-01

180

Behavior of alumina barrier layer in the supporting electrolytes for deposition of nanowired materials  

International Nuclear Information System (INIS)

In this study, we report the results obtained investigating the behavior of sulfuric and chromic acid alumina templates in typical supporting electrolytes frequently used for alternating current (ac) deposition of various nm-scaled materials. Qualitative analysis of voltammetric profiles taken for as-grown, ac-treated and annealed alumina films in a conventional tetraborate re-anodizing solution revealed dramatical changes in the properties of alumina barrier layer during ac treatment in these supporting electrolytes even at low current density. These changes were related here with the transport of protons through the barrier layer during ac treatment, discharge at the metal/oxide interface and hydrogenation of alumina material by hydrogen atoms in an upward way. This conclusion comes from the behavior of Pt/Hg|alumina|Mez+ electrode and the valence band X-ray photoelectron spectra taken from the inner part of alumina barrier layer material before and after the ac treatment.

 
 
 
 
181

Two-Dimensional Nanosheets Produced by Liquid Exfoliation of Layered Materials  

Science.gov (United States)

If they could be easily exfoliated, layered materials would become a diverse source of two-dimensional crystals whose properties would be useful in applications ranging from electronics to energy storage. We show that layered compounds such as MoS2, WS2, MoSe2, MoTe2, TaSe2, NbSe2, NiTe2, BN, and Bi2Te3 can be efficiently dispersed in common solvents and can be deposited as individual flakes or formed into films. Electron microscopy strongly suggests that the material is exfoliated into individual layers. By blending this material with suspensions of other nanomaterials or polymer solutions, we can prepare hybrid dispersions or composites, which can be cast into films. We show that WS2 and MoS2 effectively reinforce polymers, whereas WS2/carbon nanotube hybrid films have high conductivity, leading to promising thermoelectric properties.

Coleman, Jonathan N.; Lotya, Mustafa; O'Neill, Arlene; Bergin, Shane D.; King, Paul J.; Khan, Umar; Young, Karen; Gaucher, Alexandre; De, Sukanta; Smith, Ronan J.; Shvets, Igor V.; Arora, Sunil K.; Stanton, George; Kim, Hye-Young; Lee, Kangho; Kim, Gyu Tae; Duesberg, Georg S.; Hallam, Toby; Boland, John J.; Wang, Jing Jing; Donegan, John F.; Grunlan, Jaime C.; Moriarty, Gregory; Shmeliov, Aleksey; Nicholls, Rebecca J.; Perkins, James M.; Grieveson, Eleanor M.; Theuwissen, Koenraad; McComb, David W.; Nellist, Peter D.; Nicolosi, Valeria

2011-02-01

182

Behavior of alumina barrier layer in the supporting electrolytes for deposition of nanowired materials  

Energy Technology Data Exchange (ETDEWEB)

In this study, we report the results obtained investigating the behavior of sulfuric and chromic acid alumina templates in typical supporting electrolytes frequently used for alternating current (ac) deposition of various nm-scaled materials. Qualitative analysis of voltammetric profiles taken for as-grown, ac-treated and annealed alumina films in a conventional tetraborate re-anodizing solution revealed dramatical changes in the properties of alumina barrier layer during ac treatment in these supporting electrolytes even at low current density. These changes were related here with the transport of protons through the barrier layer during ac treatment, discharge at the metal/oxide interface and hydrogenation of alumina material by hydrogen atoms in an upward way. This conclusion comes from the behavior of Pt/Hg|alumina|Me{sup z+} electrode and the valence band X-ray photoelectron spectra taken from the inner part of alumina barrier layer material before and after the ac treatment.

Jagminas, Arunas, E-mail: jagmin@ktl.mii.l [Institute of Chemistry, A. Gostauto 9, 01108 Vilnius (Lithuania); Cesuniene, Asta [Institute of Chemistry, A. Gostauto 9, 01108 Vilnius (Lithuania); Vrublevsky, Igor [Department of Microelectronics, Belarusian State University of Informatics and Radioelectronics, 6 Brovka str, Minsk 220013 (Belarus); Jasulaitiene, Vitalija; Ragalevicius, Rimas [Institute of Chemistry, A. Gostauto 9, 01108 Vilnius (Lithuania)

2010-03-30

183

Synthesis of layered cathode material Li[Co x Mn1- x ]O2 from layered double hydroxides precursors  

International Nuclear Information System (INIS)

Cathode materials Li[Co x Mn1- x ]O2 for lithium secondary batteries have been prepared by a new route-precursor method of layered double hydroxides (LDHs). In situ high-temperature X-ray diffraction (HT-XRD) and thermogravimetric analysis coupled with mass spectrometry (TG-MS) were used to monitor the structural transformation during the reaction of CoMn LDHs and LiOH.H2O: firstly the layered structure of LDHs transformed to an intermediate phase with spinel structure; then the distortion of the structure occurred with the intercalation of Li+ into the lattice, resulting in the formation of layered Li[Co x Mn1- x ]O2 with ?-NaFeO2 structure. Extended X-ray absorption fine structure (EXAFS) data showed that the Co-O bonding length and the coordination number of Co were close to those of Mn in Li[Co x Mn1- x ]O2, which indicates that the local environments of the transitional metals are rather similar. X-ray photoelectron spectroscopy (XPS) was used to measure the oxidation state of Co and Mn. The influences of Co/Mn ratio on both the structure and electrochemical property of Li[Co x Mn1- x ]O2 have been investigated by XRD and electrochemical tests. It has been found that the products synthesized by the precursor method demonstrated a rather stable cycling behavemonstrated a rather stable cycling behavior, with a reversible capacity of 122.5 mAh g-1 for the layered material Li[Co0.80Mn0.20]O2. - Graphical abstract: In situ HT-XRD and TG-MS were used to monitor the structural transformation during the reaction of CoMn LDHs and LiOH.H2O: firstly the layered structure of LDHs transformed to an intermediate phase with spinel structure; then intercalation of Li+ occurred, which results in the formation of layered Li[Co x Mn1- x ]O2 with ?-NaFeO2 structure. The structure and the electrochemical properties of Li[Co x Mn1- x ]O2 were studied

184

Abrasive wear mechanisms and surface layer structure of refractory materials after mechanical working  

International Nuclear Information System (INIS)

The mechanisms of abrasive wear and surface layer structure formation after different kinds of mechanical working are considered in terms of fracture and plastic deformation mechanisms for various refractory materials. The principles for classification of abrasive wear mechanisms are proposed, the four types of wear mechanisms are distinguished for various combinations of fractures and plastic deformation types. The concept of characteristic deformation temperature t* (knee temperature) is used. Detailed examples are given of investigating the surface layer structures in grinded crystals of sapphire and molybdenum. The amorphisation tendency of the thinnest surface layer while mechanical polishing is discussed separately. 19 refs., 11 figs., 2 tabs. (Author)

185

Shape-selective sieving layers on an oxide catalyst surface.  

Science.gov (United States)

New porous materials such as zeolites, metal-organic frameworks and mesostructured oxides are of immense practical utility for gas storage, separations and heterogeneous catalysis. Their extended pore structures enable selective uptake of molecules or can modify the product selectivity (regioselectivity or enantioselectivity) of catalyst sites contained within. However, diffusion within pores can be problematic for biomass and fine chemicals, and not all catalyst classes can be readily synthesized with pores of the correct dimensions. Here, we present a novel approach that adds reactant selectivity to existing, non-porous oxide catalysts by first grafting the catalyst particles with single-molecule sacrificial templates, then partially overcoating the catalyst with a second oxide through atomic layer deposition. This technique is used to create sieving layers of Al(2)O(3) (thickness, 0.4-0.7 nm) with 'nanocavities' (layers result in selectivity (up to 9:1) towards less hindered reactants in otherwise unselective, competitive photocatalytic oxidations and transfer hydrogenations. PMID:23174984

Canlas, Christian P; Lu, Junling; Ray, Natalie A; Grosso-Giordano, Nicolas A; Lee, Sungsik; Elam, Jeffrey W; Winans, Randall E; Van Duyne, Richard P; Stair, Peter C; Notestein, Justin M

2012-12-01

186

Optical properties of atomic layer deposited materials and their application in silicon waveguides  

Science.gov (United States)

Atomic layer deposition (ALD) is a promising method to grow optical materials on waveguide structures. Propagation loss analysis indicates that amorphous TiO2 and Al2O3 films are promising for the waveguide purposes. Instead, polycrystalline ZnO does not work properly as a waveguide by itself, but the waveguiding properties can probably be enhanced by introducing intermediate Al2O3 layers. The wide variety of available materials, conformal growth properties and low scattering losses of many ALD films enable their usage in various waveguide applications. Experimental coating of silicon waveguides is discussed.

Alasaarela, Tapani; Hiltunen, Jussi; Khanna, Amit; Säynätjoki, Antti; Tervonen, Ari; Honkanen, Seppo

2010-02-01

187

Two-Dimensional Nanosheets Produced by Liquid Exfoliation of Layered Materials  

Digital Repository Infrastructure Vision for European Research (DRIVER)

If they could be easily exfoliated, layered materials would become a diverse source of two-dimensional crystals whose properties would be useful in applications ranging from electronics to energy storage. We show that layered compounds such as MoS(2), WS(2), MoSe(2), MoTe(2), TaSe(2), NbSe(2), NiTe(2), BN, and Bi(2)Te(3) can be efficiently dispersed in common solvents and can be deposited as individual flakes or formed into films. Electron microscopy strongly suggests that the material is exf...

Coleman, Jn; Lotya, M.; O Neill, A.; Bergin, Sd; King, Pj; Khan, U.; Young, K.; Gaucher, A.; S.; Smith, Rj; Shvets, Iv; Arora, Sk; Stanton, G.; Kim, Hy; Lee, K.

2011-01-01

188

Injectable materials with magnetically controlled anisotropic porosity.  

Science.gov (United States)

We propose a method to create aligned porosity in injectable materials by using magnetically responsive microrods as pore forming sacrificial templates. Rod alignment occurs through the application of an external magnetic field after injecting the material into the desired end location. Removal of the sacrificial templates through dissolution or resorption generates porosity in deliberately tuned orientations after injection, offering a powerful method to design the porous architecture of injectable materials. PMID:23030632

Sommer, Marianne R; Erb, Randall M; Studart, André R

2012-10-24

189

Crystallographic dependence of the lateral undercut wet etch rate of Al0.5In0.5P in diluted HCl for III-V sacrificial release  

DEFF Research Database (Denmark)

The authors investigated the use of InAlP as a sacrificial layer lattice-matched to GaAs when diluted hydrochloric acid is used for sacrificial etching. They show that InAlP can be used to fabricate submicrometer air gaps in micro-opto-electro-mechanical systems and that a selectivity toward GaAs larger than 500 is achieved. This selectivity enables fabrication control of the nanometer-size structures required in photonic crystal and high-index contrast subwavelength grating structures. The crystallographic dependence of the lateral etch rate in InAlP is shown to be symmetric around the ?110? directions where an etch rate of 0.5??m/min is obtained at 22?°C in HCl:2H2O. Since the etch rate in the ?100? directions exceeds by ten times that of the ?110? directions, InAlP may be used in sacrificial release of high-aspect ratio structures. Free-hanging structures with length to air-gap aspect ratios above 600 are demonstrated by use of critical point drying following the sacrificial etch.

Ansbæk, Thor; Semenova, Elizaveta

2013-01-01

190

Investigation of Materials for Boundary Layer Control in a Supersonic Wind Tunnel  

Science.gov (United States)

During operation of the NASA Glenn Research Center 15- by 15-Centimeter Supersonic Wind Tunnel (SWT), a significant, undesirable corner flow separation is created by the three-dimensional interaction of the wall and floor boundary layers in the tunnel corners following an oblique-shock/ boundary-layer interaction. A method to minimize this effect was conceived by connecting the wall and floor boundary layers with a radius of curvature in the corners. The results and observations of a trade study to determine the effectiveness of candidate materials for creating the radius of curvature in the SWT are presented. The experiments in the study focus on the formation of corner fillets of four different radii of curvature, 6.35 mm (0.25 in.), 9.525 mm (0.375 in.), 12.7 mm (0.5 in.), and 15.875 mm (0.625 in.), based on the observed boundary layer thickness of 11.43 mm (0.45 in.). Tests were performed on ten candidate materials to determine shrinkage, surface roughness, cure time, ease of application and removal, adhesion, eccentricity, formability, and repeatability. Of the ten materials, the four materials which exhibited characteristics most promising for effective use were the heavy body and regular type dental impression materials, the basic sculpting epoxy, and the polyurethane sealant. Of these, the particular material which was most effective, the heavy body dental impression material, was tested in the SWT in Mach 2 flow, and was observed to satisfy all requirements for use in creating the corner fillets in the upcoming experiments on shock-wave/boundary-layer interaction.

Braafladt, Alexander; Lucero, John M.; Hirt, Stefanie M.

2013-01-01

191

Mixed-layered bismuth--oxygen--iodine materials for capture and waste disposal of radioactive iodine  

Energy Technology Data Exchange (ETDEWEB)

Materials and methods of synthesizing mixed-layered bismuth oxy-iodine materials, which can be synthesized in the presence of aqueous radioactive iodine species found in caustic solutions (e.g. NaOH or KOH). This technology provides a one-step process for both iodine sequestration and storage from nuclear fuel cycles. It results in materials that will be durable for repository conditions much like those found in Waste Isolation Pilot Plant (WIPP) and estimated for Yucca Mountain (YMP). By controlled reactant concentrations, optimized compositions of these mixed-layered bismuth oxy-iodine inorganic materials are produced that have both a high iodine weight percentage and a low solubility in groundwater environments.

Krumhansl, James L; Nenoff, Tina M

2015-01-06

192

Mixed-layered bismuth-oxygen-iodine materials for capture and waste disposal of radioactive iodine  

Science.gov (United States)

Materials and methods of synthesizing mixed-layered bismuth oxy-iodine materials, which can be synthesized in the presence of aqueous radioactive iodine species found in caustic solutions (e.g. NaOH or KOH). This technology provides a one-step process for both iodine sequestration and storage from nuclear fuel cycles. It results in materials that will be durable for repository conditions much like those found in Waste Isolation Pilot Plant (WIPP) and estimated for Yucca Mountain (YMP). By controlled reactant concentrations, optimized compositions of these mixed-layered bismuth oxy-iodine inorganic materials are produced that have both a high iodine weight percentage and a low solubility in groundwater environments.

Krumhansl, James L; Nenoff, Tina M

2013-02-26

193

A novel nanocomposite material prepared by intercalating photoresponsive dendrimers into a layered double hydroxide  

International Nuclear Information System (INIS)

A novel combination for an inorganic-organic nanocomposite material was demonstrated. Anthryl dendron, i.e., poly(amidoamine) dendron with an anthracene chromophore group at the focal point, was incorporated in the interlayer space of ZnAl-NO3 type layered double hydroxide (LDH) through an anion-exchange reaction. The photoabsorption and fluorescence properties of the resulting material were different from those of the bare anthryl dendron molecule. It was suggested that the change in photochemical properties was due to the organization and ?-? interaction of anthracene chromophores within the interlayer of the LDH. - Graphical abstract: A novel inorganic-organic nanocomposite material, a layered double hydroxide (LDH) containing photoresponsive dendrimers in the interlayer space, was successfully prepared through an ion-exchange reaction. The resulting material exhibited unique photochemical properties, compared to those of the bare photoresponsive dendrimer molecule.

194

Development of a Biocompatible Layer-by-Layer Film System Using Aptamer Technology for Smart Material Applications  

Directory of Open Access Journals (Sweden)

Full Text Available Aptamers are short, single-stranded nucleic acids that fold into well-defined three dimensional (3D structures that allow for binding to a target molecule with affinities and specificities that can rival or in some cases exceed those of antibodies. The compatibility of aptamers with nanostructures such as thin films, in combination with their affinity, selectivity, and conformational changes upon target interaction, could set the foundation for the development of novel smart materials. In this study, the development of a biocompatible aptamer-polyelectrolyte film system was investigated using a layer-by-layer approach. Using fluorescence microscopy, we demonstrated the ability of the sulforhodamine B aptamer to bind its cognate target while sequestered in a chitosan-hyaluronan film matrix. Studies using Ultraviolet-visible (UV-Vis spectrophotometry also suggest that deposition conditions such as rinsing time and volume play a strong role in the internal film interactions and growth mechanisms of chitosan-hyaluronan films. The continued study and development of aptamer-functionalized thin films provides endless new opportunities for novel smart materials and has the potential to revolutionize the field of controlled release.

Amanda Foster

2014-05-01

195

A dynamic priority-based approach to concurrent toolpath planning for multi-material layered manufacturing  

Digital Repository Infrastructure Vision for European Research (DRIVER)

This paper presents an approach to concurrent toolpath planning for multi-material layered manufacturing (MMLM) to improve the fabrication efficiency of relatively complex prototypes. The approach is based on decoupled motion planning for multiple moving objects, in which the toolpaths of a set of tools are independently planned and then coordinated to deposit materials concurrently. Relative tool positions are monitored and potential tool collisions detected at a predefined rate. When a pote...

Choi, Sh; Zhu, Wk

2010-01-01

196

Method of forming oxidation layers to metal materials in contact with water in nuclear power plants  

International Nuclear Information System (INIS)

Purpose: To form oxidation layers excellent in water-proofness on metal materials in contact with water in nuclear power plants at a relatively low temperature and within a short period of time. Method: When cathode polarization is applied at least to a portion of metal materials in contact with water to be formed with oxidation layers, oxidation layers are formed in a high temperature water at about 200 deg C and in a relatively short period of time. The oxidation layers have a greater suppression effect against corrosions than oxidation layers formed under the anode polarization. That is, it is possible to form oxidation layers of high corrosion inhibiting effect, which have been formed so far at a high temperature of 200 deg C in a period of about 2000 hours, within about 200 hours at an identical temperature in an accelerated manner. As a result, corrosion products can be suppressed from being formed in feedwater circuits at the initial operation stage of the nuclear power plant and it is possible to realize a further reduction in the dose rate at a pipeway surfaces in the plant due to activation of corrosion products introduced into the reactor. (Kamimura, M.)

197

Approximate Electromagnetic Cloaking of a Dielectric Sphere Using Homogeneous Isotropic Multi-Layered Materials  

Directory of Open Access Journals (Sweden)

Full Text Available In cloaking, a body is hidden from detection by surrounding it by a coating consisting of an unusual anisotropic nonhomogeneous material. The permittivity and permeability of such a cloak are determined by the coordinate transformation of compressing a hidden body into a point or a line. The radially-dependent spherical cloaking shell can be approximately discretized into many homogeneous anisotropic layers; each anisotropic layer can be replaced by a pair of equivalent isotropic sub-layers, where the effective medium approximation is used to find the parameters of these two equivalent sub-layers. In this work, the scattering properties of cloaked dielectric sphere is investigated using a combination of approximate cloaking, where the dielectric sphere is transformed into a small sphere rather than to a point, together with discretizing the cloaking material using pairs of homogeneous isotropic sub-layers. The back-scattering normalized radar cross section, the scattering patterns are studied and the total scattering cross section against the frequency for different number of layers and transformed radius.

Hany M. Zamel

2013-10-01

198

Dynamic Response of Layered TiB/Ti Functionally Graded Material Specimens  

International Nuclear Information System (INIS)

This paper covers the dynamic response of rectangular (25.4x101.6x3.175 mm) specimens manufactured from layers of TiB/Ti. The layers contained volume fractions of TiB that varied from 0 to 85% and thus formed a functionally graded material. Witness samples of the 85% TiB material were also tested to provide a baseline for the statistical variability of the test techniques. Static and dynamic tests were performed to determine the in situ material properties and fundamental frequencies. Damping in the material/ fixture was also found from the dynamic response. These tests were simulated using composite beam theory which gave an analytical solution, and using finite element analysis. The response of the 85% TiB specimens was found to be much more uniform than the functionally graded material and the dynamic response more uniform than the static response. A least squares analysis of the data using the analytical solutions were used to determine the elastic modulus and Poisson's ratio of each layer. These results were used to model the response in the finite element analysis. The results indicate that current analytical and numerical methods for modeling the material give similar and adequate predictions for natural frequencies if the measured property values were used. The models did not agree as well if the properties from the manufacturer or those of Hill and Linn were used

199

Polymer/graphite oxide composites as high-performance materials for electric double layer capacitors  

Energy Technology Data Exchange (ETDEWEB)

A single graphene sheet represents a carbon material with the highest surface area available to accommodating molecules or ions for physical and chemical interactions. Here we demonstrate in an electric double layer capacitor the outstanding performance of graphite oxide for providing a platform for double layer formation. Graphite oxide is generally the intermediate compound for obtaining separated graphene sheets. Instead of reduction with hydrazine, we incorporate graphite oxide with a poly(ethylene oxide)-based polymer and anchor the graphene oxide sheets with poly(propylene oxide) diamines. This polymer/graphite oxide composite shows in a ''dry'' gel-electrolyte system a double layer capacitance as high as 130 F g{sup -1}. The polymer incorporation developed here can significantly diversify the application of graphene-based materials in energy storage devices. (author)

Tien, Chien-Pin; Teng, Hsisheng [Department of Chemical Engineering and Center for Micro/Nano Science and Technology, National Cheng Kung University, No. 1 Ta-Hsueh Road, Tainan 70101 (China)

2010-04-15

200

The collective mechanism of mass transport in surface layers of irradiated materials  

International Nuclear Information System (INIS)

The new collective mechanism of mass transport connected with diffusion of submicroscopic dislocation loops (SDL) which can act in surface layers of radiated crystalline materials is proposed and substantiated. It is shown that in real conditions SDL can diffuse essentially faster then point defects

 
 
 
 
201

Method of interlayer tunneling for studies of layered high temperature superconductors and charge density wave materials  

Energy Technology Data Exchange (ETDEWEB)

A brief review of recent results on interlayer tunneling spectroscopy of layered high temperature superconductors (HTS) and charge density wave (CDW) materials is presented demonstrating high capability of this method for studies of both electron condensed states. (copyright 2006 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

Latyshev, Yu.I.; Orlov, A.P. [IREE, RAS, Mokhovaya 11-7, 101999 Moscow (Russian Federation); Monceau, P. [CRTBT-CNRS, BP 166, 38042 Grenoble (France); Brazovskii, S.A. [LPTM-CNRS, Universite Paris-Sud, Paris 91405 (France); Yamashita, T. [NIMS, 305-0047 Ibaraki, Tsukuba (Japan); Bulaevskii, L.N. [Los Almos National Lab., Los Alamos, NM 87545 (United States)

2006-09-15

202

Acquaintance with international and Iranian organizations responsible to replacement of the destroying materials of ozone layer  

International Nuclear Information System (INIS)

Acquaintance with international and Iranian organizations responsible to replacement of the depletion materials of ozone layer is discussed. Vienna Convection for depletion is briefly reviewed and then Montreal Protocol is described. Finally,Islamic Republic of Iran programs in this respect are represented

203

Effect of base layer materials on physiological and perceptual responses to exercise in personal protective equipment.  

Science.gov (United States)

Ten men (non-firefighters) completed a 110 min walking/recovery protocol (three 20-min exercise bouts, with recovery periods of 10, 20, and 20 min following successive bouts) in a thermoneutral laboratory while wearing firefighting personal protective equipment over one of four base layers: cotton, modacrylic, wool, and phase change material. There were no significant differences in changes in heart rate, core temperature, rating of perceived exertion, thermal discomfort, and thermal strain among base layers. Sticking to skin, coolness/hotness, and clothing humidity sensation were more favorable (p firefighting ensembles (base layer + turnout gear) indicated differences in thermal protective performance and total heat loss among the base layers and among ensembles; however, differences in heat dissipation did not correspond with physiological responses during exercise or recovery. PMID:23849898

Smith, Denise L; Arena, Logan; DeBlois, Jacob P; Haller, Jeannie M; Hultquist, Eric M; Lefferts, Wesley K; Russell, Tim; Wu, Annie; Fehling, Patricia C

2014-05-01

204

Study on coating layer of ceramic materials for SFR fuel slugs  

Energy Technology Data Exchange (ETDEWEB)

The plasma-sprayed coating can provide the crucible with a denser, more durable, coating layer, compared with the more friable coating layer formed by slurry-coating. Plasma-sprayed coatings are consolidated by mechanical interlocking of the molten particles impacting on the substrate and are dense by the heat applied by the plasma. The objective of this study is to develop a coating method and material for crucibles to prevent material interactions with the U-Zr/U-TRU-Zr fuels. Reducing these interactions will result in a fuel loss reduction. According to coating and U-Zr interaction results preformed in previous experience, Y{sub 2}O{sub 3}, TiC, and TaC coating materials were selected as promising coating materials Various combinations of coating conditions such as; coating thickness, double multi-layer coating methods were investigated to find the bonding effect on the substrate in pursuit of more effective ways to withstand the thermal stresses. To develop a coating method and material for crucibles to prevent material interactions with U-TRU-Zr fuels, the refractory coating was performed using vacuum plasma-sprayed method onto niobium rod. The various combinations of coating conditions such as; coating thickness, double multi-layer coating methods were investigated to find the bonding effect to withstand the thermal stress. Most of coating method samples did not maintain integrity in the U-Zr-RE melt because of the cracks or the microcracks of the coating layer, presumably formed from the thermal expansion difference. Only the double-layer coated rod with TaC and Y{sub 2}O{sub 3} powders, which is, which consists of vacuum plasma-sprayed TaC bond coating with the coating thickness of 100?m onto niobium rod and vacuum plasma-sprayed Y{sub 2}O{sub 3} coating with the coating thickness of 100?m on the top of the bond coating layer, survived the 2 cycles dipping test of U-Zr-RE melt this is likely caused by good adhesion of the TaC coating onto the niobium rod and the chemical inertness of Y{sub 2}O{sub 3} coating material in U-Zr-RE melt.

Song, Hoon; Kim, Jonghwan; Kim, Kihwan; Ko, Youngmo; Woo, Yoonmyung; Lee, Chanbock [Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of)

2013-05-15

205

Thermophysical Properties of Mars' North Polar Layered Deposits and Related Materials from Mars Odyssey THEMIS  

Science.gov (United States)

The presence of a thick sequence of horizontal layers of ice-rich material at Mars north pole, dissected by troughs and eroding at its margins, is undoubtedly telling us something about the evolution of Mars climate [1,2] we just don t know what yet. The North Polar Layered Deposits (NPLD) most likely formed as astronomically driven climate variations led to the deposition of conformable, areally extensive layers of ice and dust over the polar region. More recently, the balance seems to have fundamentally shifted to net erosion, as evidenced by the many troughs within the NPLD and the steep, arcuate scarps present near its margins, both of which expose layering. We defined a number of Regions of Interest ROI) for THEMIS to target as part of the Mars Odyssey Participating Scientist program. We use these THEMIS data in order to understand the morphology and color/thermal properties of the NPLD and related materials over relevant (i.e., m to km) spatial scales. We have assembled color mosaics of our ROIs in order to map the distribution of ices, the different layered units, dark material, and underlying basement. The color information from THEMIS is crucial for distinguishing these different units which are less distinct on Mars Orbiter Camera images. We wish to understand the nature of the marginal scarps and their relationship to the dark material. Our next, more ambitious goal is to derive the thermophysical properties of the different geologic materials using THEMIS and Mars Global Surveyor Thermal Emission Spectrometer TES) data.

Vasavada, A. R.; Richardson, M. I.; Byrne, S.; Ivanov, A. B.; Christensen, P. R.

2003-01-01

206

Comparative dissolution study of drug and inert isomalt based core material from layered pellets.  

Science.gov (United States)

Layered and coated pellets were formulated to control the release of the diclofenac sodium selected as model drug. A highly water soluble isomalt inert pellet core material was used to osmotically modulate the drug release through the swellable polyvinyl acetate coating layer. Image analysis was applied to determine the shape parameters and the swelling behavior of the pellets. UV-spectroscopy and liquid chromatography with refractive index detection were applied to measure the concentration of the model drug and the core materials. Simultaneous dissolution of both the diclofenac sodium and isomalt was observed. Relationship was found between the dissolution profile of the drug and the core material which linear correlation was independent on the coating level. The latter enables the modulation of drug release beside the permeability control of the swelled coating polymer. PMID:24996006

Kállai-Szabó, Nikolett; Luhn, Oliver; Bernard, Joerg; Kállai-Szabó, Barnabás; Zelkó, Romána; Antal, István

2014-09-01

207

Suitability of Structural Aluminium Profiles as Sacrificial Anode for Carbon Steel  

Directory of Open Access Journals (Sweden)

Full Text Available The life of low carbon steels in many small scale structures can be remarkably prolonged by complementary sacrificial anode cathodic protection (SACP but for constraints in availability of specialty anodes. Suitability of commonly available structural aluminium profiles as sacrificial anodes for low carbon steel has been investigated. Three different profiles were studied. Bare and coated steel samples were found to migrate clearly too cathodic potential regimes when coupled with the press-finish BS1470:6000 AlMgSi series alloy in a chloride medium. No weight loss was observed for the coated steel sample, while the aluminium profile showed dissolution. This alloy, commonly available in press-finish profiles for structural purposes, is therefore recommendable as sacrificial anodes for complementary SACP of low carbon steel structures under atmospheric or aqueous exposures.

Iyiola O. OTUNNIYI

2012-11-01

208

Growth of molten core debris pools in concrete. Part II. A. Pool growth in composite beds; B. Effect of overlaying steel layers. Final report, March 1, 1978-September 30, 1979  

International Nuclear Information System (INIS)

The heat and mass transfer processes taking place in molten core debris/concrete systems have been experimentally investigated. Two types of experiments have been conducted. The first experiment simulates the growth of a molten debris pool in a composite sacrificial bed. This experiment models debris pool growth in an inner, low-melting point, sacrificial material zone followed by a melting attack on the concrete bed. The purpose of the inner zone is to quickly melt and dilute the debris pool so that its subsequent downward growth in the concrete may be slowed. In the second experiment a two-layer immiscible liquid system is volumetrically heated and allowed to melt into a low-density gas releasing solid bed which is miscible in the initially-higher-density bottom liquid. The solid melts, mixes with, and dilutes the bottom liquid pool until its density is lower than that of the top liquid

209

A thin layer including a carbon material improves the rate capability of an electric double layer capacitor  

Science.gov (United States)

We present a new method to improve the rate capability of an electric double layer capacitor (EDLC) using a thin polymer layer having a high concentration of carbon material on a current collector (CLC). A novel thermocuring coating composed of a glycol-chitosan, a pyromellitic acid and a conductive carbon powder can form stable CLC on a metal foil current collector simply by spreading and curing at 160 °C for a couple of minutes. We compared the performance of some demonstration EDLC cells using three kinds of current collector: a conventional aluminum oxide foil for EDLC, an aluminum foil and an aluminum foil with CLC. The cell with the CLC had a much higher rate capability than the cell without CLC. Only the CLC cell was able to discharge at a current density of 500C. This cell shows a slight deterioration in capacity in a high temperature, continuous charging, life test, and the CLC has a suppressing effect on the internal resistance increase of EDLCs. The use of a CLC film current collector is one of the most effective and simple methods for the improvement of EDLC rate performance. In particular, a current collector consisting of aluminum foil coupled with a CLC promises to be a low cost alternative to the aluminum oxide foil commonly used in EDLCs.

Sato, Takaya; Marukane, Shoko; Morinaga, Takashi; Uemura, Taichi; Fukumoto, Kunihiro; Yamazaki, Satoshi

2011-03-01

210

Improvement of lithium storage performance of Sn-alloy anode materials by a polypyrrole protective layer  

Science.gov (United States)

The SnO2-based anode with improved reversible capacity and cyclability was achieved by employing a protective layer composed of crosslinked polypyrrole nanowires. Scanning electron microscopy measurement was performed to characterize the surface and cross section morphology of electrodes before and after cycling. The crosslinked polypyrrole nanowire protective layer with good elasticity adhered to the SnO2 surface could form a network, leading to buffer the volumetric swelling of active materials during the lithiation/delithiation process. A good cycling stability and an excellent rate capability of the modified electrode were achieved.

Peng, Peng; Wen, Zhaoyin; Liu, Yu; Jin, Jun

2015-01-01

211

Comparison of some coating techniques to fabricate barrier layers on packaging materials  

International Nuclear Information System (INIS)

Atomic layer deposition (ALD), electron beam evaporation, magnetron sputtering and a sol-gel method were used to deposit thin aluminum oxide coatings onto two different fiber-based packaging materials of commercial board grades coated with synthetic and biodegradable polymers. Significant decreases in both the water vapor and oxygen permeation rates were observed. With each technique the barrier performance was improved. However, among the techniques tested ALD was found to be most suitable. Our results moreover revealed that biodegradable polylactic acid-coated paperboard with a 25-nm thick layer of aluminum oxide grown by ALD on top of it showed promising barrier characteristics against water vapor and oxygen.

212

Slab waveguide with air core layer and anisotropic left-handed material claddings as a sensor  

Science.gov (United States)

A three-layer slab waveguide with air core layer and anisotropic left-handed material claddings is investigated for sensing applications. Different from the waveguide mode sensors and surface plasmon resonance sensors in which the analyte is placed in the evanescent field region, the proposed sensor contains the sample in the core region that supports the oscillating field. Due to the strong concentration of the electromagnetic field in the analyte medium, the proposed device exhibits unusual sensitivity enhancement. The simulations revealed that the sensitivity improvement of TE3 mode compared to conventional evanescent wave sensor is approximately a factor of 20.

Taya, S. A.

2014-12-01

213

Microscopic observation of pattern attack by aggressive ions on finished surface of aluminium alloy sacrificial anode  

International Nuclear Information System (INIS)

This paper presents the results of a microscopic observation on submerged finished surface of aluminium alloy sacrificial anode. Experimental tests were carried out on polished surface aluminium anode exposed to seawater containing aggressive ions in order to observe of pattern corrosion attack on corroding surface of anode. Results have shown, at least under the present testing condition, that surface of sacrificial anode were attack by an aggressive ion such as chloride along grain boundaries. In addition, results of microanalysis showed that the corrosion products on surface of aluminium alloy have Al, Zn and O element for all sample and within the pit was consists of Al, Zn, O and Cl element. (author)

214

Highly efficient gate-tunable photocurrent generation in vertical heterostructures of layered materials  

Science.gov (United States)

Layered materials of graphene and MoS2, for example, have recently emerged as an exciting material system for future electronics and optoelectronics. Vertical integration of layered materials can enable the design of novel electronic and photonic devices. Here, we report highly efficient photocurrent generation from vertical heterostructures of layered materials. We show that vertically stacked graphene-MoS2-graphene and graphene-MoS2-metal junctions can be created with a broad junction area for efficient photon harvesting. The weak electrostatic screening effect of graphene allows the integration of single or dual gates under and/or above the vertical heterostructure to tune the band slope and photocurrent generation. We demonstrate that the amplitude and polarity of the photocurrent in the gated vertical heterostructures can be readily modulated by the electric field of an external gate to achieve a maximum external quantum efficiency of 55% and internal quantum efficiency up to 85%. Our study establishes a method to control photocarrier generation, separation and transport processes using an external electric field.

Yu, Woo Jong; Liu, Yuan; Zhou, Hailong; Yin, Anxiang; Li, Zheng; Huang, Yu; Duan, Xiangfeng

2013-12-01

215

Frequency characterization of thin soft magnetic material layers used in spiral inductors  

Energy Technology Data Exchange (ETDEWEB)

The paper details the characterization of thin magnetic materials layers, particularly soft materials, with respect to their behaviour in frequency (from 10 MHz to 1 GHz). The proposed method is suitable for any soft but insulating magnetic material; Yttrium Iron Garnet (YIG) is used as an example. The principle is based on a comparison between simulations for different values of the permeability and measurement values versus frequency of planar inductor structures; an experimental validation is proposed as well. Thin magnetic material is first deposited on an alumina substrate using RF sputtering technique; a planar spiral winding of copper is then deposited on the magnetic material by the same technique. The effective permeability versus frequency is obtained by comparing two samples of spiral windings with and without magnetic material. Network analyser measurements on samples of various geometrical dimensions and of different thicknesses are necessary to determine the effective magnetic permeability; we have obtained a relative effective permeability of about 30 for seven turns spiral inductor of a 17 {mu}m YIG film. - Highlights: Black-Right-Pointing-Pointer A simple and original method is presented for the characterization of soft magnetic layer. Black-Right-Pointing-Pointer This is a non-destructive method based on standard equipment. Black-Right-Pointing-Pointer The principle is based on a comparison between simulations and measurement. Black-Right-Pointing-Pointer An experimental validation is proposed as well.

Kriga, Adoum; Allassem, Desire [Universite de Lyon, F-42023 Saint Etienne (France); Universite de Saint Etienne, Jean Monnet, F-42023 Saint Etienne (France); LT2C, F-42023 Saint Etienne (France); Soultan, Malloum [Universite de N' Djamena N' Djamena (Chad); Chatelon, Jean-Pierre; Siblini, Ali [Universite de Lyon, F-42023 Saint Etienne (France); Universite de Saint Etienne, Jean Monnet, F-42023 Saint Etienne (France); LT2C, F-42023 Saint Etienne (France); Allard, Bruno [Laboratoire Ampere INSA-Lyon 20, avenue Einstein 69621 Villeurbanne Cedex France (France); Rousseau, Jean Jacques, E-mail: rousseau@univ-st-etienne.fr [Universite de Lyon, F-42023 Saint Etienne (France); Universite de Saint Etienne, Jean Monnet, F-42023 Saint Etienne (France); LT2C, F-42023 Saint Etienne (France)

2012-07-15

216

Nonlinear Localization due to a Double Negative Defect Layer in a One-Dimensional Photonic Crystal Containing Single Negative Material Layers  

International Nuclear Information System (INIS)

We investigate the effects of introducing a defect layer in a one-dimensional photonic crystal containing single negative material layers on the transmission properties. The width of the defect layer is taken to be the same or smaller than the period of the structure. Different cases of the defect layer being linear or nonlinear and double positive or double negative are discussed. It is found that only a nonlinear double negative layer gives rises to a localized mode within the zero-?eff gap in this kind of structure. It is also shown that the important characteristics of the nonlinear defect mode such as its frequency, its FWHM and the threshold of the associated bistability can be controlled by changing the widths of the defect layer and the host layers

217

Layered tungsten oxide-based organic/inorganic hybrid materials I: Infrared and Raman study  

CERN Document Server

Tungsten oxide-organic layered hybrid materials have been studied by infrared and Raman spectroscopy, and demonstrate a difference in bonding nature as the length of the interlayer organic `spacer' molecule is increased. Ethylenediamine-tungsten oxide clearly displays a lack of terminal -NH3^+ ammonium groups which appear in hybrids with longer alkane molecules, thus indicating that the longer chains are bound by electrostatic interactions as well as or in place of the hydrogen bonding that must be present in the shorter chain ethylenediamine hybrids. The presence of organic molecules between the tungsten oxide layers, compared with the layered tungstic acid H2WO4, shows a decrease in the apical W=O bond strength, as might be expected from the aforementioned electrostatic interaction.

Ingham, B

2004-01-01

218

Ta-C micro-composite material formed by heat treatment of plasma carburized layer  

Energy Technology Data Exchange (ETDEWEB)

Tantalum-carbon micro-composite material (MCM) was produced by a process which combines plasma carburizing and heat treatment. The fabrication was performed in inductively coupled radio-frequency plasma, using CH{sub 4}-H{sub 2}-Ar mixtures, followed by a two-step heat treatment which includes solid solution and aging. The crystallography, microstructure and composition of the intermediate layers and of the MCMs were characterized by X-ray diffraction, scanning electron microscopy, energy-dispersive analysis and atomic force microscopy. The mechanical properties of the layers and of the MCMs were studied by laterally resolved depth-sensing indentation. It was found that the size and hardness within the recrystallized grains and carbon-rich grain boundaries are strongly related to the composition and thickness of the initial carburized layer. The mechanisms involved in the different process steps, in particular redistribution of Ta-C compounds and carbon diffusion towards the film bulk, are discussed.

Raveh, A.; Rubinshtein, A.; Weiss, M.; Mintz, M.H.; Klemberg-Sapieha, J.E.; Martinu, L

2004-11-01

219

Ta-C micro-composite material formed by heat treatment of plasma carburized layer  

International Nuclear Information System (INIS)

Tantalum-carbon micro-composite material (MCM) was produced by a process which combines plasma carburizing and heat treatment. The fabrication was performed in inductively coupled radio-frequency plasma, using CH4-H2-Ar mixtures, followed by a two-step heat treatment which includes solid solution and aging. The crystallography, microstructure and composition of the intermediate layers and of the MCMs were characterized by X-ray diffraction, scanning electron microscopy, energy-dispersive analysis and atomic force microscopy. The mechanical properties of the layers and of the MCMs were studied by laterally resolved depth-sensing indentation. It was found that the size and hardness within the recrystallized grains and carbon-rich grain boundaries are strongly related to the composition and thickness of the initial carburized layer. The mechanisms involved in the different process steps, in particular redistribution of Ta-C compounds and carbon diffusion towards the film bulk, are discussed

220

Microstructural characterization of mixed-material deposition layer on the LHD divertor tiles by using nano-geological diagnosis  

Science.gov (United States)

Fusion plasma research crucially needs to understand the characteristics of the deposition layer that forms in the vacuum vessel because of the migration of plasma-facing materials. Such a deposition layer can accumulate on the fuel particles on account of a co-deposition process and can be a source of dust in the plasma. In this study, nano-geological diagnosis which uses a focused ion beam (FIB) fabrication technique and transmission electron microscope (TEM) observations, has been applied to the mixed-material deposition layer formed in a large helical device (LHD). A cross-sectional view of the deposition layer with nanometer resolution was successfully observed. The total thickness of the layer was estimated at ˜8 ?m, and it has very fine and stratified layer structures in the nanometer level. The characteristics of each layer are indicative of the operational history of the LHD and the mechanism of dust formation by layer flaking.

Tokitani, M.; Masuzaki, S.; Yoshida, N.; Sagara, A.; Noda, N.; Yamada, H.; LHD Experiment Group

2013-07-01

 
 
 
 
221

Microstructural characterization of mixed-material deposition layer on the LHD divertor tiles by using nano-geological diagnosis  

International Nuclear Information System (INIS)

Fusion plasma research crucially needs to understand the characteristics of the deposition layer that forms in the vacuum vessel because of the migration of plasma-facing materials. Such a deposition layer can accumulate on the fuel particles on account of a co-deposition process and can be a source of dust in the plasma. In this study, nano-geological diagnosis which uses a focused ion beam (FIB) fabrication technique and transmission electron microscope (TEM) observations, has been applied to the mixed-material deposition layer formed in a large helical device (LHD). A cross-sectional view of the deposition layer with nanometer resolution was successfully observed. The total thickness of the layer was estimated at ?8 ?m, and it has very fine and stratified layer structures in the nanometer level. The characteristics of each layer are indicative of the operational history of the LHD and the mechanism of dust formation by layer flaking

222

Extremely efficient liquid exfoliation and dispersion of layered materials by unusual acoustic cavitation.  

Science.gov (United States)

Layered materials must be exfoliated and dispersed in solvents for diverse applications. Usually, highly energetic probe sonication may be considered to be an unfavourable method for the less defective exfoliation and dispersion of layered materials. Here we show that judicious use of ultrasonic cavitation can produce exfoliated transition metal dichalcogenide nanosheets extraordinarily dispersed in non-toxic solvent by minimising the sonolysis of solvent molecules. Our method can also lead to produce less defective, large graphene oxide nanosheets from graphite oxide in a short time (within 10?min), which show high electrical conductivity (>20,000?S m(-1)) of the printed film. This was achieved by adjusting the ultrasonic probe depth to the liquid surface to generate less energetic cavitation (delivered power ~6?W), while maintaining sufficient acoustic shearing (0.73?m s(-1)) and generating additional microbubbling by aeration at the liquid surface. PMID:24875584

Han, Joong Tark; Jang, Jeong In; Kim, Haena; Hwang, Jun Yeon; Yoo, Hyung Keun; Woo, Jong Seok; Choi, Sua; Kim, Ho Young; Jeong, Hee Jin; Jeong, Seung Yol; Baeg, Kang-Jun; Cho, Kilwon; Lee, Geon-Woong

2014-01-01

223

DETERMINATION OF MECHANICAL STRENGTH OF SAME MATERIAL DOUBLE-LAYER RECTANGULAR TABLETS  

Directory of Open Access Journals (Sweden)

Full Text Available The mechanical strength of same material composite beams of Avicel PHI02, Starch 1500 and Emcompress were assessed by three-point bending test. To provide an improved method of comparing the strength of the tablets, the tensile strength of the specimens was calculated by equations based on stress analysis. Increasing the compaction pressure led to decrease of the porosity of the compacted tablets while the overall mass of the composite tablets were kept constant. Meanwhile, the values of fracture load and strengths (including tensile and shear raised by increasing the compaction pressure. However, when the lower layer was compacted twice, the value of tensile stress of the lower layer was more than its value in a single compacted tablet with the same material. This observation was attributed to the extent of the reduction of porosity during compaction of the single tablets which raised in their tensile strength values.

ISMAEL HARTRIAN

2000-07-01

224

Development of N-layer materials for SNS junction and SQUID applications  

International Nuclear Information System (INIS)

Materials characteristics including water reactivity, oxygen loss, electromigration of oxide ions, and interfacial reactivity problems have plagued attempts to produce reliable and reproducible cuprate SNS superconductor junctions. In an effort to solve some of these formidable problems, new N-layer compounds from the family of R1-xCaxBa2-yLayCu3-zMzO7-? (R = Y, Gd and Pr; M = Co, Ni and Zn; 0 2Cu3O7-? phase and the modified materials exhibit enhanced durability properties. The compounds have been utilized to make both SNS junctions and SQUID devices

225

Guided Modes in a Four-Layer Slab Waveguide with Dispersive Left-Handed Material  

Directory of Open Access Journals (Sweden)

Full Text Available A four-layer slab waveguide including left-handed material is investigated numerically in this paper. Considering left-handed material dispersion, we find eight TE guided modes as frequency from 4 GHz to 6 GHz. The fundamental mode can exist, and its dispersion curves are insensitive to the waveguide thickness. Besides, the total power fluxes of TE guided modes are analyzed and corresponding new properties are found, such as: positive and negative total power fluxes coexist; at maximum value of frequency, we find zero total power flux, etc. Our results may be of benefit to the optical waveguide technology.

Lufa Shen

2010-05-01

226

Thin layer activation for materials research and development at IAM of the European commission  

International Nuclear Information System (INIS)

After a short description of the cyclotron of the European Commission Institute for Advanced Materials (IAM)-Ispra site (italy) and its activities, an overview of the Thin Layer Activation (TLA) technique is given. The use of TLA for materials studies is illustrated with examples of ongoing research within the IAM. Notably this includes corrosion studies and laboratory and industrial wear testing. Due to its specific properties, including area selectivity, high sensitivity and speed in addition to the possibility for in-situ and on-line monitoring, TLA can contribute significantly to monitor surface degradation in both research and industrial applications. (authors)

227

Polycrystalline SiC as source material for the growth of fluorescent SiC layers  

DEFF Research Database (Denmark)

Polycrystalline doped SiC act as source for fluorescent SiC. We have studied the growth of individual grains with different polytypes in the source material. We show an evolution and orientation of grains of different polytypes in polycrystalline SiC ingots grown by the Physical Vapor Transport method. The grain influence on the growth rate of fluorescent SiC layers grown by a sublimation epitaxial process is discussed in respect of surface kinetics.

Kaiser, M.; Hupfer, T.

2013-01-01

228

Surface wave sensors based on nanometric layers of strongly absorbing materials.  

Science.gov (United States)

We demonstrate the excitation of guided modes in thin layers of strongly absorbing chalcogenide glasses. These modes are similar to surface plasmon polaritons in terms of resonance width and shift with changes in the permittivity of the surrounding medium. We exploit these characteristics to demonstrate a high sensitivity chalcogenide glass refractive index sensor that outperforms gold surface plasmon resonance sensors at short wavelengths in the visible. This demonstration opens a new range of possibilities for sensing using different materials. PMID:22535033

Zhang, Yichen; Arnold, Christophe; Offermans, Peter; Gómez Rivas, Jaime

2012-04-23

229

Employing Adaptive Finite Elements to Model Squeezing of a Layered Material in 3D  

Directory of Open Access Journals (Sweden)

Full Text Available In this paper we employ 3D hp-adaptive finite element method (hp-FEM to model the behavior of a squeezed layered material. Under a moderate pressure, the linear elasticity model can be used to imitate the process. Thanks to hp-adaptivity, only the regions where the error rate is high are refined, making sure that all peculiarities are automatically localized

Marcin Sieniek

2013-11-01

230

Deformation kinetics of layered personal protective material under impact via terahertz reflectometry  

Science.gov (United States)

Terahertz dynamic scanning reflectometry (TDSR) was used for measuring layered materials' deformation kinetics spectra. Multi-layered materials are used for protective devices such as helmet and body armor. An in-situ measurement of deformation profile and other dynamic characteristics is important when such material is subjected to ballistic impacts. Current instrumentation is limited in their abilities to provide sub-surface information in a non-destructive fashion. A high sensitivity TDSR has been used to measure dynamic surface deformation characteristics in real-time (in-situ) and also at post deformation (ex-situ). Real-time ballistic deformation kinetics was captured with a high speed measurement system. The kinetics spectra was used to compute a number of crucial parameters such as deformation length and its propagation profile, the relaxation position, and the macroscopic vibration profile. In addition, the loss of mass due to impact was quantified for accurate determination of the trauma causing energy. For non-metallic substrates, a transmitted beam was used to calibrate mass loss, a priori, of the laminate layers due to impact. Deformation kinetics information may then be used to formulate trauma diagnosis conditions from blunt hit via the Sturdivan criterion [1]. The basic difference in the proposed approach is that here diagnostic criteria are inferred by measuring the helmet itself; no need to draw blood or any biopsy from the patient.

Rahman, Anis; Rahman, Aunik; Mentzer, Mark A.

2014-05-01

231

New Material Development for Surface Layer and Surface Technology in Tribology Science to Improve Energy Efficiency  

Science.gov (United States)

This paper reviews the development of new material and surface technology in tribology and its contribution to energy efficiency. Two examples of the economic benefits, resulted from the optimum tribology in the transportation sector and the manufacturing industry are discussed. The new materials are proposed to modify the surface property by laminating the bulk material with thin layer/coating. Under a suitable condition, the thin layer on a surface can provide a combination of good wear, a low friction and corrosion resistance for the mechanical components. The innovation in layer technology results molybdenum disulfide (MoS2), diamond like carbon (DLC), cubic boron nitride (CBN) and diamond which perform satisfactory outcome. The application of the metallic coatings to carbon fibre reinforced polymer matrix composites (CFRP) has the capacity to provide considerable weight and power savings for many engineering components. The green material for lubricant and additives such as the use of sunflower oil which possesses good oxidation resistance and the use of mallee leaves as bio-degradable solvent are used to answer the demand of the environmentally friendly material with good performance. The tribology research implementation for energy efficiency also touches the simple things around us such as: erasing the laser-print in a paper with different abrasion techniques. For the technology in the engineering surface, the consideration for generating the suitable surface of the components in running-in period has been discussed in order to prolong the components life and reduce the machine downtime. The conclusion, tribology can result in reducing manufacturing time, reducing the maintenance requirements, prolonging the service interval, improving durability, reliability and mechanical components life, and reducing harmful exhaust emission and waste. All of these advantages will increase the energy efficiency and the economic benefits.

Ismail, R.; Tauviqirrahman, M.; Jamari, Jamari; Schipper, D. J.

2009-09-01

232

46 CFR 35.01-25 - Sacrificial anode installations-TB/ALL.  

Science.gov (United States)

...sacrificial anodes in cargo tanks utilized for the carriage...be permitted in cargo tanks under the following criteria...above the bottom of the tank. Special consideration...given when structural design prevents the anodes...installation and a chemical analysis of the alloy...

2010-10-01

233

Fabrication of transferable Al(2)O(3) nanosheet by atomic layer deposition for graphene FET.  

Science.gov (United States)

Without introducing defects in the monolayer of carbon lattice, the deposition of high-? dielectric material is a significant challenge because of the difficulty of high-quality oxide nucleation on graphene. Previous investigations of the deposition of high-? dielectrics on graphene have often reported significant degradation of the electrical properties of graphene. In this study, we report a new way to integrate high-? dielectrics with graphene by transferring a high-? dielectric nanosheet onto graphene. Al2O3 film was deposited on a sacrificial layer using an atomic layer deposition process and the Al2O3 nanosheet was fabricated by removing the sacrificial layer. Top-gated graphene field-effect transistors were fabricated and characterized using the Al2O3 nanosheet as a gate dielectric. The top-gated graphene was demonstrated to have a field-effect mobility up to 2200 cm(2)/(V s). This method provides a new method for high-performance graphene devices with broad potential impacts reaching from high-frequency high-speed circuits to flexible electronics. PMID:24483324

Jung, Hanearl; Park, Jusang; Oh, Il-Kwon; Choi, Taejin; Lee, Sanggeun; Hong, Juree; Lee, Taeyoon; Kim, Soo-Hyun; Kim, Hyungjun

2014-02-26

234

A proposed method to determine the adherence for the layers made out of thermal sprayed materials on internal cylindrical surfaces  

Directory of Open Access Journals (Sweden)

Full Text Available The paper presents an investigation method for the adherence of the layers made out of thermal sprayed materials on the inner surface of some parts. The base material is made of steel. The deposition procedure was the electric arc thermal spraying, flame spraying asnd plasma spraying and the filler materials used were: copper, brass and aluminum bronze. The proposed method analyses the adherence force by measuring the shear unit fracture stress of the deposited layers.

Adrian V. Petrica

2005-10-01

235

Transmission of Thermonuclear Detonations through Layers of Burned Material in Carbon-Oxygen White Dwarfs  

Science.gov (United States)

In three-dimensional delayed-detonation models of type Ia supernovae, detonations propagate through funnels of degenerate carbon-oxygen matter that are left unburned by turbulent deflagrations in central parts of a white dwarf. Some of these funnels can be disconnected from the rest of the unburned material, thus creating unburned pockets that cannot be directly reached by a detonation wave. These pockets may or may not ignite when strong shocks generated by detonations reach them through layers of burned material. In this work, we study the detonation transmission phenomena in exploding white dwarfs using one-dimensional time-dependent numerical simulations based on reactive Euler equations. The thermonuclear burning of carbon-oxygen mixture is modeled by a 13-nuclei alpha network. We use a steady-state solution for the reaction-zone structure of a one-dimensional detonation wave as an initial condition. Time-dependent computations performed for a fully resolved carbon reaction scale show that a detonation shock passing through a layer of burned material can initiate a new detonation or decay. The critical thickness of burned material that allows the detonation reignition is a function of density. This work was supported in part by the NASA ATP program (NRA-02-OSS-01-ATP) and by the Naval Research Laboratory (NRL) through the Office of Naval Research.

Gamezo, V. N.; Oran, E. S.

2006-06-01

236

Radiation transport through a plasma boundary layer between armatures and material surfaces  

International Nuclear Information System (INIS)

This paper reports on the ablation of rail and insulator materials by plasma armatures which limits the velocity and the component lifetime of electromagnetic launchers. The photon radiation from the armature is the dominant form of energy transfer causing the ablation. However, not all of the escaping radiation actually is transmitted to the ablating surface and hence vapor shielding is to occur in the plasma boundary layer. A 1 D, time dependent self-consistent hydrodynamics model with a multigroup flux limited diffusion approximation for radiative transfer is used to estimate the energy transmission and the amount of ablated material. It has been found that the vapor shield is optically thin for photon energies where most of the incident source radiation is distributed, thus the simple diffusion model for radiative transfer would overestimate the radiation flux at the material surface

237

Atomic layer deposition of nanostructured materials for energy and environmental applications  

Energy Technology Data Exchange (ETDEWEB)

Atomic layer deposition (ALD) is a thin film technology that in the past two decades rapidly developed from a niche technology to an established method. It proved to be a key technology for the surface modification and the fabrication of complex nanostructured materials. In this Progress Report, after a short introduction to ALD and its chemistry, the versatility of the technique for the fabrication of novel functional materials will be discussed. Selected examples, focused on its use for the engineering of nanostructures targeting applications in energy conversion and storage, and on environmental issues, will be discussed. Finally, the challenges that ALD is now facing in terms of materials fabrication and processing will be also tackled. (Copyright copyright 2012 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

Marichy, Catherine [Department of Chemistry, CICECO, University of Aveiro (Portugal); Bechelany, Mikhael [Institut Europeen des Membranes (ENSCM, UMR CNRS 5635), Universite Montpellier 2, Montpellier (France); Pinna, Nicola [Department of Chemistry, CICECO, University of Aveiro (Portugal); World Class University (WCU) Program of Chemical, Convergence for Energy and Environment (C2E2), School of Chemical and Biological Engineering, College of Engineering, Seoul National University (SNU), Seoul (Korea, Republic of)

2012-02-21

238

Surface reconstruction and chemical evolution of stoichiometric layered cathode materials for lithium-ion batteries.  

Science.gov (United States)

The present study sheds light on the long-standing challenges associated with high-voltage operation of LiNi(x)Mn(x)Co(1-2x)O2 cathode materials for lithium-ion batteries. Using correlated ensemble-averaged high-throughput X-ray absorption spectroscopy and spatially resolved electron microscopy and spectroscopy, here we report structural reconstruction (formation of a surface reduced layer, to transition) and chemical evolution (formation of a surface reaction layer) at the surface of LiNi(x)Mn(x)Co(1-2x)O2 particles. These are primarily responsible for the prevailing capacity fading and impedance buildup under high-voltage cycling conditions, as well as the first-cycle coulombic inefficiency. It was found that the surface reconstruction exhibits a strong anisotropic characteristic, which predominantly occurs along lithium diffusion channels. Furthermore, the surface reaction layer is composed of lithium fluoride embedded in a complex organic matrix. This work sets a refined example for the study of surface reconstruction and chemical evolution in battery materials using combined diagnostic tools at complementary length scales. PMID:24670975

Lin, Feng; Markus, Isaac M; Nordlund, Dennis; Weng, Tsu-Chien; Asta, Mark D; Xin, Huolin L; Doeff, Marca M

2014-01-01

239

In situ ellipsometry of surface layer of non-metallic transparent materials during its finish processing  

International Nuclear Information System (INIS)

For modern technology applications it is important to develop non-contact methods of control of the modification of dielectric materials surface layer. The aim of the work is to determine the level of roughness changes in the surface layer of non-metallic material, optical glass BK-7, and to control it by in situ ellipsometry. The probing light spot was formed at a second (lower) reflective surface of the plate being studied during its mechanical processing at direct observation of these changes. The fine mechanical polishing was carried out for 2 hours by using the grinding-polishing machine installed directly on the sample table of ellipsometer LEF-3M. The angle of light incidence was close to 70 degree. The ellipsometric parameters, were determined within the mechanically processed area. For this purpose, the probing light beam passed two times through the sample and then returned to the initial (air) medium, where its polarization state was studied. The polarized beam falls on lower plate surface polished by conventional technology using grinding-polishing CeO2-based instrument 'Aquapol' (grain size 1 micron). The time dependences of the ellipsometric parameters during the surface layer treatment were studied. In these dependences the tendency of changes of ellipsometric parameters indicates the surface roughness enhancement

240

Vertically stacked multi-heterostructures of layered materials for logic transistors and complementary inverters.  

Science.gov (United States)

Graphene has attracted considerable interest for future electronics, but the absence of a bandgap limits its direct applicability in transistors and logic devices. Recently, other layered materials such as molybdenum disulphide (MoS(2)) have been investigated to address this challenge. Here, we report the vertical integration of multi-heterostructures of layered materials for the fabrication of a new generation of vertical field-effect transistors (VFETs) with a room temperature on-off ratio > 10(3) and a high current density of up to 5,000 A cm(-2). An n-channel VFET is created by sandwiching few-layer MoS(2) as the semiconducting channel between a monolayer graphene sheet and a metal thin film. This approach offers a general strategy for the vertical integration of p- and n-channel transistors for high-performance logic applications. As an example, we demonstrate a complementary inverter with a larger-than-unity voltage gain by vertically stacking graphene, Bi(2)Sr(2)Co(2)O(8) (p-channel), graphene, MoS(2) (n-channel) and a metal thin film in sequence. The ability to simultaneously achieve a high on-off ratio, a high current density and a logic function in such vertically stacked multi-heterostructures can open up possibilities for three-dimensional integration in future electronics. PMID:23241535

Yu, Woo Jong; Li, Zheng; Zhou, Hailong; Chen, Yu; Wang, Yang; Huang, Yu; Duan, Xiangfeng

2013-03-01

 
 
 
 
241

Nanostructure and thermal stability of Co oxide multi-layer materials  

International Nuclear Information System (INIS)

High-resolution microscopy and x-ray refraction were carried out for surveying thermal and environmental stability in nano-multi-layer materials, which are candidate for soft x-ray mirror materials. Co3O4/SiO2 nano-layer: This system shows excellent X-ray refraction property, and has a flat structure at nano-scale, where the thermal stability was high up to 600degC. Co3O4/BN nano-layer: This showed not enough x-ray refraction property, and has a nano-particle structure of Co3O4. Such difference may be caused by less wet-ability and chemical affinity. Thermal stability at high temperature up to 700-1000degC: The nano-particle structure in Co3O4/BN system up to 600degC, where such high stability consists with qualitative thermodynamic data, even if nano-scale particles. (author)

242

Li-rich layer-structured cathode materials for high energy Li-ion batteries  

Science.gov (United States)

Li-rich layer-structured xLi2MnO3 ? (1 - x)LiMO2 (M = Mn, Ni, Co, etc.) materials have attracted much attention due to their extraordinarily high reversible capacity as the cathode material in Li-ion batteries. To better understand the nature of this type of materials, this paper reviews history of development of the Li-rich cathode materials, and provides in-depth study on complicated crystal structures and reaction mechanisms during electrochemical charge/discharge cycling. Despite the fabulous capability at low rate, several drawbacks still gap this type of high-capacity cathode materials from practical applications, for instance the large irreversible capacity loss at first cycle, poor rate capability, severe voltage decay and capacity fade during electrochemical charge/discharge cycling. This review will also address mechanisms for these inferior properties and propose various possible solutions to solve above issues for future utilization of these cathode materials in commercial Li-ion batteries.

Li, Liu; Lee, Kim Seng; Lu, Li

2014-08-01

243

Tuning the Transport Properties of Layered Materials for Thermoelectric Applications using First-Principles Calculations  

Thermoelectric materials can convert waste heat into electric power and thus provide a way to reduce the dependence on fossil fuels. Our aim is to model the underlying materials properties and, in particular, the transport as controlled by electrons and lattice vibrations. The goal is to develop an understanding of the thermoelectric properties of selected materials at a fundamental level. The structural, electronic, optical, and phononic properties are studied in order to tune the transport, focusing on KxRhO2, NaxRhO2, PtSb2 and Bi2Se3. The investigations are based on density functional theory as implemented in the all electron linearized augmented plane wave plus local orbitals WIEN2k and pseudo potential Quantum-ESPRESSO codes. The thermoelectric properties are derived from Boltzmann transport theory under the constant relaxation time approximation, using the BoltzTraP code. We will discuss first the changes in the electronic band structure under variation of the cation concentration in layered KxRhO2 in the 2H phase and NaxRhO2 in the 3R phase. We will also study the hydrated phase. The deformations of the RhO6 octahedra turn out to govern the thermoelectric properties, where the high Seebeck coefficient results from ”pudding mold" bands. We investigate the thermoelectric properties of electron and hole doped PtSb2, which is not a layered material but shares “pudding mold" bands. PtSb2 has a high Seebeck coefficient at room temperature, which increases significantly under As alloying by bandgap opening and reduction of the lattice thermal conductivity. Bi2Se3 (bulk and thin film) has a larger bandgap then the well-known thermoelectric material Bi2Te3, which is important at high temperature. The structural stability, electronic structure, and transport properties of one to six quintuple layers of Bi2Se3 will be discussed. We also address the effect of strain on a single quintuple layer by phonon band structures. We will analyze the electronic and transport properties of Tl-doped Bi2Se3 under strain, focusing on the giant Rashba spin splitting (Tl doping breaks the inversion symmetry in Bi2Se3) and its dependence on biaxial tensile and compressive strain.

Saeed, Yasir

2014-05-11

244

Emergency sacrificial sealing method in filters, equipment, or systems  

Energy Technology Data Exchange (ETDEWEB)

A system seals a filter or equipment component to a base and will continue to seal the filter or equipment component to the base in the event of hot air or fire. The system includes a first sealing material between the filter or equipment component and the base; and a second sealing material between the filter or equipment component and the base and proximate the first sealing material. The first sealing material and the second seal material are positioned relative to each other and relative to the filter or equipment component and the base to seal the filter or equipment component to the base and upon the event of fire the second sealing material will be activated and expand to continue to seal the filter or equipment component to the base in the event of hot air or fire.

Brown, Erik P

2014-09-30

245

Emanation thermal analysis for characterization of surface and near surface layers of advanced materials  

International Nuclear Information System (INIS)

A non traditional method, called emanation thermal analysis (ETA), was used the for characterization of surface and near surface layers of SiC based materials. This method consists in the measurement of the release of inert gas (radon) from the samples previously labeled to the depth of several tens of nanometers with the inert gas atoms. The ETA results brought about information about microstructure changes and transport properties of SiC/SiCf composites on heating in the range 30-1300degC in argon and air, respectively. The annealing of structure irregularities which served as diffusion paths for radon was evaluated. The temperature range of the formation and crystallization of the silica layer resulting after oxidation of the SiC/SiCf sample on heating in air was determined from the ETA results. (author)

246

Processing of hazardous material, or damage treatment method for shallow layer underground storage structure  

International Nuclear Information System (INIS)

In radioactive waste processing facilities and shallow layer underground structures for processing hazardous materials, sheet piles having freezing pipes at the joint portions are spiked into soils at the periphery of a damaged portion of the shallow layer underground structure for processing or storing hazardous materials. Liquid nitrogen is injected to the freezing pipes to freeze the joint portions of adjacent sheet piles. With such procedures, continuous waterproof walls are formed surrounding the soils at the peripheries of the damaged portion. Further, freezing pipes are disposed in the surrounding soils, and liquid nitrogen is injected to freeze the soils. The frozen soils are removed, and artificial foundation materials are filled in the space except for the peripheries of the damaged portion after the removal thereof, and liquid suspension is filled in the peripheries of the damaged portion, and restoration steps for closing the damaged portion are applied. Then, the peripheries of the damaged portion are buried again. With such procedures, series of treatments for removing contaminated soils and repairing a damaged portion can be conducted efficiently at a low cost. (T.M.)

247

Finite Element Analysis of Layered Fiber Composite Structures Accounting for the Material's Microstructure and Delamination  

Science.gov (United States)

The present paper focuses on composite structures which consist of several layers of carbon fiber reinforced plastics (CFRP). For such layered composite structures, delamination constitutes one of the major failure modes. Predicting its initiation is essential for the design of these composites. Evaluating stress-strength relation based onset criteria requires an accurate representation of the through-the-thickness stress distribution, which can be particularly delicate in the case of shell-like structures. Thus, in this paper, a solid-shell finite element formulation is utilized which allows to incorporate a fully three-dimensional material model while still being suitable for applications involving thin structures. Moreover, locking phenomena are cured by using both the EAS and the ANS concept, and numerical efficiency is ensured through reduced integration. The proposed anisotropic material model accounts for the material's micro-structure by using the concept of structural tensors. It is validated by comparison to experimental data as well as by application to numerical examples.

Stier, Bertram; Simon, Jaan-Willem; Reese, Stefanie

2014-05-01

248

Assessment of doses caused by electrons in thin layers of tissue-equivalent materials, using MCNP  

International Nuclear Information System (INIS)

Absorbed doses caused by electron irradiation were calculated with Monte Carlo N-Particle transport code (MCNP) for thin layers of tissue-equivalent materials. The layers were so thin that the calculation of energy deposition was on the border of the scope of MCNP. Therefore, in this article application of three different methods of calculation of energy deposition is discussed. This was done by means of two scenarios: in the first one, electrons were emitted from the centre of a sphere of water and also recorded in that sphere; and in the second, an irradiation with the PTB Secondary Standard BSS2 was modelled, where electrons were emitted from an 90Sr/90Y area source and recorded inside a cuboid phantom made of tissue-equivalent material. The speed and accuracy of the different methods were of interest. While a significant difference in accuracy was visible for one method in the first scenario, the difference in accuracy of the three methods was insignificant for the second one. Considerable differences in speed were found for both scenarios. In order to demonstrate the need for calculating the dose in thin small zones, a third scenario was constructed and simulated as well. The third scenario was nearly equal to the second one, but a pike of lead was assumed to be inside the phantom in addition. A dose enhancement (caused by the pike of lead) of ?113 % was recorded for a thin hollow cylinder at a depth of 0.007 cm, which the basal-skin layer of 0.007 cm, which the basal-skin layer is referred to in particular. Dose enhancements between 68 and 88 % were found for a slab with a radius of 0.09 cm for all depths. All dose enhancements were hardly noticeable for a slab with a cross-sectional area of 1 cm2 which is usually applied to operational radiation protection. (authors)

249

Complex layered materials and periodic electromagnetic band-gap structures: Concepts, characterizations, and applications  

Science.gov (United States)

The main objective of this dissertation is to characterize and create insight into the electromagnetic performances of two classes of composite structures, namely, complex multi-layered media and periodic Electromagnetic Band-Gap (EBG) structures. The advanced and diversified computational techniques are applied to obtain their unique propagation characteristics and integrate the results into some novel applications. In the first part of this dissertation, the vector wave solution of Maxwell's equations is integrated with the Genetic Algorithm (GA) optimization method to provide a powerful technique for characterizing multi-layered materials, and obtaining their optimal designs. The developed method is successfully applied to determine the optimal composite coatings for Radar Cross Section (RCS) reduction of canonical structures. Both monostatic and bistatic scatterings are explored. A GA with hybrid planar/curved surface implementation is also introduced to efficiently obtain the optimal absorbing materials for curved structures. Furthermore, design optimization of the non-uniform Luneburg and 2-shell spherical lens antennas utilizing modal solution/GA-adaptive-cost function is presented. The lens antennas are effectively optimized for both high gain and suppressed grating lobes. The second part demonstrates the development of an advanced computational engine, which accurately computes the broadband characteristics of challenging periodic electromagnetic band-gap structures. This method utilizes the Finite Difference Time Domain (FDTD) technique with Periodic Boundary Condition/Perfectly Matched Layer (PBC/PML), which is efficiently integrated with the Prony scheme. The computational technique is successfully applied to characterize and present the unique propagation performances of different classes of periodic structures such as Frequency Selective Surfaces (FSS), Photonic Band-Gap (PBG) materials, and Left-Handed (LH) composite media. The results are incorporated into some novel applications such as high Q nanocavity lasers, guiding the electromagnetic waves at sharp bends, and miniaturized microstrip patch antennas.

Mosallaei, Hossein

250

Unified perfectly matched layer for finite-difference time-domain modeling of dispersive optical materials.  

Science.gov (United States)

Finite-difference time-domain (FDTD) simulations of any electromagnetic problem require truncation of an often-unbounded physical region by an electromagnetically bounded region by deploying an artificial construct known as the perfectly matched layer (PML). As it is not possible to construct a universal PML that is non-reflective for different materials, PMLs that are tailored to a specific problem are required. For example, depending on the number of dispersive materials being truncated at the boundaries of a simulation region, an FDTD code may contain multiple sets of update equations for PML implementations. However, such an approach is prone to introducing coding errors. It also makes it extremely difficult to maintain and upgrade an existing FDTD code. In this paper, we solve this problem by developing a new, unified PML algorithm that can effectively truncate all types of linearly dispersive materials. The unification of the algorithm is achieved by employing a general form of the medium permittivity that includes three types of dielectric response functions, known as the Debye, Lorentz, and Drude response functions, as particular cases. We demonstrate the versatility and flexibility of the new formulation by implementing a single FDTD code to simulate absorption of electromagnetic pulse inside a medium that is adjacent to dispersive materials described by different dispersion models. The proposed algorithm can also be used for simulations of optical phenomena in metamaterials and materials exhibiting negative refractive indices. PMID:19997357

Udagedara, Indika; Premaratne, Malin; Rukhlenko, Ivan D; Hattori, Haroldo T; Agrawal, Govind P

2009-11-01

251

Characteristics of Photonic Bandgap Fibres with Hollow Core's Inner Surface Coated by a Layer Material  

International Nuclear Information System (INIS)

Hollow core's inner surface coating in a photonic bandgap fibre (PBGF) is investigated by means of finite element method. The coat material and thickness-dependence dispersion curve and group velocity dispersion are numerically studied. The coating with materials of low index or small thickness will rise up the dispersion curve but will not induce surface modes. However, coating with materials of high index or big coat thickness will induce surface modes and avoided-crossings. By varying coat material's refractive index and thickness, the appearances of surface modes and avoided-crossings can be changed. It is found that the avoided-crossing can enormously enlarge the negative dispersion which can find applications in dispersion compensation. We numerically achieve a negative dispersion as large as -21416.15 ps/nm/km. The results give a physical insight into the propagation properties of PBGFs with the hollow core coated by a layer of material and are of crucial significance in the applications of PBGF coating

252

Optical properties of PbS-doped silica optical fiber materials based on atomic layer deposition  

Science.gov (United States)

Optical properties of PbS-doped silica optical fiber materials and theoretical simulation are investigated. PbS is deposited on silica optical fiber materials by Atomic Layer Deposition (ALD) technique with Pb(tmhd)2 and H2S as Pb and S precursors, respectively. Its stoichiometry is confirmed by X-ray photoelectron spectroscopy (XPS). The valence states of S and Pb element are -2 and +2, respectively. The Raman spectra further reveal that PbS has been doped into optical fiber materials almost without destroying irregular rings structure in silica material network. And there are distinct absorption bands at 248 and 352 nm. Fluorescence spectra are obtained with 330 and 350 nm pumping, two fluorescence peaks at 768 and 808 nm, respectively. In addition, the microstructure models for PbS-doped optical fiber materials are built on Gaussian09 platform, and its optical properties of the absorption and emission spectra are calculated using density functional theory (DFT) and time-dependent density functional theory (TDDFT) methods. There are obvious absorption and emission peaks at 325.7 and 769.8 nm, respectively, which are in good agreement with experiments.

Dong, Yanhua; Wen, Jianxiang; Pang, Fufei; Chen, Zhenyi; Wang, Jie; Luo, Yanhua; Peng, Gangding; Wang, Tingyun

2014-11-01

253

Production of layered zirconium-steel composite materials by solid-phase welding  

International Nuclear Information System (INIS)

The method of solid-phase welding is applied to produce layered composite materials on the basis of zirconium and stainless steel type 12Kh18N10T with niobium and copper interlayers used in nuclear reactor fuel elements as well as in control devices with nondetachable joints. It is shown that adhesion joints of zirconium and steel obtained by vacuum hot rolling possess high stability under conditions of thermal cycling and alternating loading. A correlation is established between structural changes in the composite and its softening under thermal cycling within the range of 200-800 deg C

254

Defect physics, delithiation mechanism, and electronic and ionic conduction in layered lithium manganese oxide cathode materials  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Layered LiMnO2 and Li2MnO3 are of great interest for lithium-ion battery cathodes because of their high theoretical capacities. The practical application of these materials is, however, limited due to poor electrochemical performance. We herein report a comprehensive first-principles study of defect physics in LiMnO2 and Li2MnO3 using hybrid density functional calculations. We find that manganese antisites have low formation energies in LiMnO2 and may act as nucleation sites...

Hoang, Khang

2014-01-01

255

Material technology trends to improve multi-layer coatings: Challenges to traditional thinking  

Energy Technology Data Exchange (ETDEWEB)

Current global acceptance of the three layer polyethylene coating system for the exterior coating of steel pipelines (for almost any environment on-shore/off-shore for oil, gas or water pipelines) has helped to expand the present coating use. The focus of this paper will be on coating material changes by technology, to up-grade the end use of the coating system and to present those changes to the engineering and corrosion community to the benefit of the end user or client.

Cox, J.W. [DuPont Canada Inc., Calgary, Alberta (Canada); Grimshaw, D. [Jotun Powder Coatings Ltd., Scunthorpe (United Kingdom); D`Agostino, C. [Novacor Chemicals Ltd., Mississauga, Ontario (Canada)

1996-12-31

256

Crystal Chemical Concept of Arrangement and Function of Layered Superconducting Materials  

Digital Repository Infrastructure Vision for European Research (DRIVER)

The crystal chemical concept of arrangement and function of layered superconducting materials is supposed. The concept is based on results of our investigation of crystal chemistry of high-temperature superconductors (HTSC) cuprates, diborides AB2 and borocarbides of nickel RNi2B2C. According to these results: (1) the main role in appearance of superconductivity played by the structural fragments - sandwiches A2(CuO2) in HTSC cuprates, A2(B2) in diborides and RB(Ni) in nicke...

Volkova, L. M.; Polyshchuk, S. A.; Magarill, S. A.; Herbeck, F. E.

2002-01-01

257

Fabrication of Meso-Porous Sintered Metal Thin Films by Selective Etching of Silica Based Sacrificial Template  

Directory of Open Access Journals (Sweden)

Full Text Available Meso-porous metal materials have enhanced surface energies offering unique surface properties with potential applications in chemical catalysis, molecular sensing and selective separation. In this paper, commercial 20 nm diameter metal nano-particles, including silver and copper were blended with 7 nm silica nano-particles by shear mixing. The resulted powders were cold-sintered to form dense, hybrid thin films. The sacrificial silica template was then removed by selective etching in 12 wt% hydrofluoric acid solutions for 15 min to reveal a purely metallic meso-porous thin film material. The impact of the initial silica nano-particle diameter (7–20 nm as well as the sintering pressure (5–20 ton·m?2 and etching conditions on the morphology and properties of the final nano-porous thin films were investigated by porometry, pyknometery, gas and liquid permeation and electron microscopy. Furthermore, the morphology of the pores and particle aggregation during shear mixing were assessed through cross-sectioning by focus ion beam milling. It is demonstrated that meso-pores ranging between 50 and 320 nm in average diameter and porosities up to 47% can be successfully formed for the range of materials tested.

Ludovic F. Dumee

2014-08-01

258

Explosive magnetic device with a three-layered liner for radiographic study of dynamic strength of materials  

International Nuclear Information System (INIS)

This paper presents the device comprising the helical and disk explosive magnetic generator with a three-layered cylindrical liner (Al-dielectric-Cu) designed for experiments at the current of 33-35 MA. Polyethylene or water was used as a dielectric layer. The experiments tested successfully the idea to study the dynamic strength of materials by X-raying the growth of amplitude of axisymmetric sinusoidal perturbations machined initially on the outer surface of the examined inner layer of the liner

259

Automatic identification of single- and/or few-layer thin-film material  

DEFF Research Database (Denmark)

One or more digital representations of single- (101) and/or few-layer (102) thin- film material are automatically identified robustly and reliably in a digital image (100), the digital image (100) having a predetermined number of colour components, by - determining (304) a background colour component of the digital image (100) for each colour component, and - determining or estimating (306) a colour component of thin-film material to be identified in the digital image (100) for each colour component by obtaining a pre-determined contrast value (C R; C G; C B) for each colour component and multiplying the respective bacground colour component with a numerical difference between the pre-determined contrast value (C R; C G; C B) for a given colour component and about 1, - identifying points or parts of the image with all colour components being within a predetermined range of the determined or estimated colour component.

Jessen, Bjarke SØrensen Technical University of Denmark,

260

Holographic recording characteristics and applications of single-layer panchromatic dichromated gelatin material  

Science.gov (United States)

A high-quality single-layer panchromatic dichromated gelatin material is achieved successfully by employing new types of multi-color photosensitizers and photochemical promoters to conventional photo-crosslinking gelatin system. Its holographic recording characteristics such as spectral response, the photosensitivity of three primary colors, spectral selectivity of volume reflection hologram, angular and wavelength selectivity of volume transmission hologram, are studied in detail. Using red, green and blue lasers, namely three primary colors, the bright volume transmission and reflection holograms can be recorded on the panchromatic material at the exposure level of 30 mJ/cm2. Some preliminary results of space, angle and wavelength multiplexing holographic storage for storing multiple binary and grey-tone optical images, are also reported in this paper.

Zhu, Jianhua; Xu, Min; Chen, Ligong; Guo, Yongkang; Guo, Lurong

2005-09-01

 
 
 
 
261

OPTIMIZING A PORTABLE MICROWAVE INTERFERENCE SCANNING SYSTEM FOR NONDESTRUCTIVE TESTING OF MULTI-LAYERED DIELECTRIC MATERIALS  

International Nuclear Information System (INIS)

The projected microwave energy pattern, wave guide geometry, positioning methods and process variables have been optimized for use of a portable, non-contact, lap-top computer-controlled microwave interference scanning system on multi-layered dielectric materials. The system can be used in situ with one-sided access and has demonstrated capability of damage detection on composite ceramic armor. Specimens used for validation included specially fabricated surrogates, and ballistic impact-damaged specimens. Microwave data results were corroborated with high resolution direct-digital x-ray imaging. Microwave interference scanning detects cracks, laminar features and material properties variations. This paper presents the details of the system, the optimization steps and discusses results obtained.

262

A Method to Estimate the Dynamic Displacement and Stress of a Multi-layered Pavement with Bituminous or Concrete Materials  

Directory of Open Access Journals (Sweden)

Full Text Available In this research work, a method to estimate the dynamic characteristics of a multilayered pavement with bituminous or concrete materials is proposed. A mechanical model is established to investigate the dynamic displacement and stress of the multi-layered pavement structure. Both the flexible and the rigid pavements, corresponding to bituminous materials and concrete materials, respectively, are studied. The theoretical solutions of the multi-layered pavement structure are deduced considering the compatibility condition at the interface of the structural layers. By introducing FFT (Fast Fourier Transform algorithm, some numerical results are presented. Comparisons of the theoretical and experimental result implied that the proposed method is reasonable in predicting the stress and displacement of a multi-layered pavement with bituminous or concrete materials. DOI: http://dx.doi.org/10.5755/j01.ms.20.4.6071

Zheng LU

2014-12-01

263

Material and Doping Dependence of the Nodal and Anti-Nodal Dispersion Renormalizations in Single- and Multi-Layer Cuprates  

Energy Technology Data Exchange (ETDEWEB)

In this paper we present a review of bosonic renormalization effects on electronic carriers observed from angle-resolved photoemission spectra in the cuprates. Specifically, we discuss the viewpoint that these renormalizations represent coupling of the electrons to the lattice and review how materials dependence, such as the number of CuO{sub 2} layers, and doping dependence can be understood straightforwardly in terms of several aspects of electron-phonon coupling in layered correlated materials.

Johnston, S.; /Waterloo U. /SLAC; Lee, W.S.; /Stanford U., Geballe Lab. /SLAC; Nowadnick, E.A.; /SLAC /Stanford U., Phys. Dept.; Moritz, B.; /SLAC /North Dakota U.; Shen, Z.-X.; /Stanford U., Geballe Lab. /SLAC /Stanford U., Phys. Dept. /Stanford U., Appl. Phys. Dept.; Devereaux, T.P.; /Stanford U., Geballe Lab. /SLAC

2010-02-15

264

Material utilisation when depositing CdTe layers by inline AP-MOCVD  

Science.gov (United States)

A study was undertaken to assess the efficiency of precursors' usage during deposition of cadmium telluride (CdTe) layers via atmospheric pressure metal organic chemical vapour deposition (AP-MOCVD) for thin film photovoltaic solar cells. Precursors were released from a showerhead assembly normal to the glass substrate 0.7 mm thick (5×7.5 cm2) being deposited which was kept stationary or moved under the showerhead assembly, with speed of upto 2.25 cm/min. In order to estimate the effective precursor utilisation, the weight deposit (layer) was compared against the theoretical values calculated for ideal molar supply. The layer thickness, composition, morphology, and crystallinity were also measured using profilometry, energy dispersive X-ray (EDX), scanning electron microscopy (SEM), and X-ray diffraction (XRD), respectively. It is shown that over 40% material utilisation can be achieved depending on the deposition parameters of substrate temperature and speed, partial pressure of precursors and total gas flow. The activation energy derived from an Arrhenius plot of deposition rate equals 49 kJ mol-1 and is consistent with previous reports of MOCVD CdTe using a horizontal reactor. This confirms that, despite the very different reactor geometry, the alkyl radical homolysis and reaction mechanism applies in the case of the inline injector geometry in the work presented here. These results demonstrate an alternative path to high throughput processing of CdTe thin film solar cells by inline AP-MOCVD.

Barrioz, V.; Kartopu, G.; Irvine, S. J. C.; Monir, S.; Yang, X.

2012-09-01

265

Novel magnetic materials prepared by electrodeposition techniques: arrays of nanowires and multi-layered microwires  

International Nuclear Information System (INIS)

The fabrication process by electrodeposition routes and the study of general magnetic properties is reported for two types of nanostructured magnetic materials: (a) nickel-filled highly-ordered nanoporous alumina templates, and (b) electrodeposited Ni layers onto glass coated amorphous microwires. Arrays of Ni nanowires, about 30 nm in diameter and separated by about 100 nm, are obtained by electrodeposition into the pores of alumina membranes prepared by two-steps anodization process from highly pure aluminum substrates. Morphological studies have been performed by high resolution scanning electron microscopy (HRSEM). The study includes the optimization of preparation parameters and the magnetic characterization of the hexagonally arranged nanowire arrays, i.e. the influence of the pore diameter and the interwire distance on the coercivity of the whole nanowire array. On the other hand, multi-layered magnetic microwires have been prepared in the following sequence: a nanometric Au coat is first sputtered onto Pyrex coated FeSiB amorphous microwires followed by electrodeposition of a 500 nm thick Ni external cover. While in as-cast microwires the hysteresis loop is squared shaped (magnetic bistability), in the case of the multilayer microwire, a transverse magnetic anisotropy is induced when reducing the measuring temperature as a consequence of the stresses induced by the different thermal expansion coefficients of the various layerss layers

266

Investigation of epitaxial silicon layers as a material for radiation hardened silicon detectors  

Energy Technology Data Exchange (ETDEWEB)

Epitaxial grown thick layers ({ge} 100 micrometers) of high resistivity silicon (Epi-Si) have been investigated as a possible candidate of radiation hardened material for detectors for high-energy physics. As grown Epi-Si layers contain high concentration (up to 2 {times} 10{sup 12} cm{sup {minus}3}) of deep levels compared with that in standard high resistivity bulk Si. After irradiation of test diodes by protons (E{sub p} = 24 GeV) with a fluence of 1.5 {times} 10{sup 11} cm{sup {minus}2}, no additional radiation induced deep traps have been detected. A reasonable explanation is that there is a sink of primary radiation induced defects (interstitial and vacancies), possibly by as-grown defects, in epitaxial layers. The ``sinking`` process, however, becomes non-effective at high radiation fluences (10{sup 14} cm{sup {minus}2}) due to saturation of epitaxial defects by high concentration of radiation induced ones. As a result, at neutron fluence of 1 {times} 10{sup 14} cm{sup {minus}2} the deep level spectrum corresponds to well-known spectrum of radiation induced defects in high resistivity bulk Si. The net effective concentration in the space charge region equals to 3 {times} 10{sup 12} cm{sup {minus}3} after 3 months of room temperature storage and reveals similar annealing behavior for epitaxial as compared to bulk silicon.

Li, Z. [Brookhaven National Lab., Upton, NY (United States); Eremin, V.; Ilyashenko, I.; Ivanov, A.; Verbitskaya, E. [Russian Academy of Sciences, St. Petersburg (Russian Federation). Ioffe Physico-Technical Inst.; CERN RD-48 ROSE Collaboration

1997-12-01

267

Enhanced ionic conductivity in composite materials due to interfacial space charge layers  

International Nuclear Information System (INIS)

The ionic conductivity of a number of salts (e.g., ?-AgI, LiI, CuCl, HgI2, etc.) can be enhanced by one to three orders of magnitude with the addition of fine particles of an insoluble and nonconducting material such as Al2O3 or SiO2. Typically the conductivity increases with addition of the inert particles and reaches a peak at 10-40 vol % of the particles. The mechanism responsible for the enhanced conductivity of the composite is not understood at this time. Some claim that this effect is due to an increased concentration of charge carriers in a diffuse space charge layer near the charged surface of the particle. The goal of the present study is to test this proposed mechanism by calculating the maximum space charge layer effect and then using this result to estimate the conductivity of a composite with a random distribution of Al2O3 particles. Also, the conductivity of composite systems has been investigated assuming an ordered distribution of particles which are surrounded by a high conductivity layer

268

In-situ fabrication and fracture characteristics of structural gradient Ni/Ni-aluminide//Ti/Ti-aluminide layered materials  

Energy Technology Data Exchange (ETDEWEB)

Ni/Ni-aluminide//Ti/Ti-aluminide laminate composite, considered as a functionally gradient material, was manufactured by thin foil hot press technique. Thick intermetallic layers of NiAl and TiAl{sub 3} were formed by a self-propagating high-temperature synthesis (SHS) reaction, and thin continuous layers of Ni{sub 3}Al and TiAl were formed by a solid-state diffusion. Fracture resistance with loading along the crack arrester direction is higher than crack divider direction due to the interruption of crack growth in metal layers. The Ni{sub 3}Al and NiAl intermetallic layer showed cleavage and intergranular fracture behavior, respectively, while the fracture mode of TiAl{sub 3} layer was found to be a intragranular cleavage. The debonding between metal and intermetallic layer and the pores were observed in the Ni/Ni-aluminide layers, resulting in the lower fracture resistance. (orig.)

Chung, D.S. [Dept. of Materials, Ulsan Polytechnic Coll., Ulsan (Korea); Kim, J.K. [Dept. of Materials Engineering, Miryang National Univ., Kyungnam (Korea); Enoki, M. [Dept. of Materials Engineering, The Univ. of Tokyo, Tokyo (Japan)

2005-07-01

269

Electrical and material characterization of tantalum pentoxide (Ta2O5) charge trapping layer memory  

International Nuclear Information System (INIS)

In this experiment, tantalum pentoxide (Ta2O5) was used in a metal/oxide/high-k Ta2O5/oxide/silicon (MOHOS) novel nanocrystal memory as a trapping layer. Post-annealing treatment, which can passivate defects and improve the material quality of the high-k dielectric, was applied to optimize device performance for a better memory window and faster P/E (program/erase) cycle. Material and electrical characterization techniques including X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), atomic force microscopy (AFM), and electrical measurements were performed to analyze the device under different annealing conditions. The Ta2O5 charge trapping layer memory annealed at 900 deg. C had a higher window of 3.3 V in the current-voltage (C-V) hysteresis loop, and a higher charge retention capability than the samples prepared under various annealing conditions. These higher levels were due to the higher probability of deep-level charge trapping and lower leakage current.

270

Characterization of Elastic-plastic Material Properties for IMC Layer of ENEPIG by Using Reverse Algorithm  

Science.gov (United States)

Recently, the reliability assurance of lead-free solder to prevent environmental contamination is quite important issue for chip-scale packaging. Although lots of efforts have been devoted to the solder undergone drop, shear and creep loads, there was a little research on IMC due primarily to its thickness restriction and geometric irregularity. However, the IMC is known as the weakest layer governing failures of the solder joint. The present work is to characterize realistic material properties of the IMC for ENEPIG process. Lee's modified reverse algorithm was adopted to determine elastic-plastic stress-strain curve and so forth, after examining several methods, which requires inherently elastic data. In this context, a series of nano-indentation tests as well as corresponding simulations were carried out by changing indentation depths from 200 to 400 nm and strain rates from 0.05 to 0.10 1/s. It would be conclude that effect of strain rate is relatively small and IMC layer should be more than 5 times of indentation depth when using the recommended method, which are applicable to generate realistic material properties for further diverse structural integrity simulations.

Kim, Jong-Min; Lee, Hyun-Boo; Chang, Yoon-Suk; Choi, Jae-Boong; Kim, Young-Jin; Ji, Kum-Young

2010-05-01

271

Rediscovering black phosphorus as an anisotropic layered material for optoelectronics and electronics  

Science.gov (United States)

Graphene and transition metal dichalcogenides (TMDCs) are the two major types of layered materials under intensive investigation. However, the zero-bandgap nature of graphene and the relatively low mobility in TMDCs limit their applications. Here we reintroduce black phosphorus (BP), the most stable allotrope of phosphorus with strong intrinsic in-plane anisotropy, to the layered-material family. For 15-nm-thick BP, we measure a Hall mobility of 1,000 and 600?cm2?V-1?s-1 for holes along the light (x) and heavy (y) effective mass directions at 120?K. BP thin films also exhibit large and anisotropic in-plane optical conductivity from 2 to 5??m. Field-effect transistors using 5?nm BP along x direction exhibit an on-off current ratio exceeding 105, a field-effect mobility of 205?cm2?V-1?s-1, and good current saturation characteristics all at room temperature. BP shows great potential for thin-film electronics, infrared optoelectronics and novel devices in which anisotropic properties are desirable.

Xia, Fengnian; Wang, Han; Jia, Yichen

2014-07-01

272

Assessment of doses caused by electrons in thin layers of tissue-equivalent materials, using MCNP.  

Science.gov (United States)

Absorbed doses caused by electron irradiation were calculated with Monte Carlo N-Particle transport code (MCNP) for thin layers of tissue-equivalent materials. The layers were so thin that the calculation of energy deposition was on the border of the scope of MCNP. Therefore, in this article application of three different methods of calculation of energy deposition is discussed. This was done by means of two scenarios: in the first one, electrons were emitted from the centre of a sphere of water and also recorded in that sphere; and in the second, an irradiation with the PTB Secondary Standard BSS2 was modelled, where electrons were emitted from an (90)Sr/(90)Y area source and recorded inside a cuboid phantom made of tissue-equivalent material. The speed and accuracy of the different methods were of interest. While a significant difference in accuracy was visible for one method in the first scenario, the difference in accuracy of the three methods was insignificant for the second one. Considerable differences in speed were found for both scenarios. In order to demonstrate the need for calculating the dose in thin small zones, a third scenario was constructed and simulated as well. The third scenario was nearly equal to the second one, but a pike of lead was assumed to be inside the phantom in addition. A dose enhancement (caused by the pike of lead) of ?113 % was recorded for a thin hollow cylinder at a depth of 0.007 cm, which the basal-skin layer is referred to in particular. Dose enhancements between 68 and 88 % were found for a slab with a radius of 0.09 cm for all depths. All dose enhancements were hardly noticeable for a slab with a cross-sectional area of 1 cm(2), which is usually applied to operational radiation protection. PMID:23576794

Heide, Bernd

2013-10-01

273

Gigantic swelling of inorganic layered materials: a bridge to molecularly thin two-dimensional nanosheets.  

Science.gov (United States)

Platy microcrystals of a typical layered material, protonated titanate, have been shown to undergo an enormous degree of swelling in aqueous solutions of various amines, including tertiary amines, quaternary ammonium hydroxides, and primary amines. Introducing these solutions expanded the crystal gallery height by up to ~100-fold. Through systematic analysis, we determined that ammonium ion intercalation is predominantly affected by the acid-base equilibrium and that the degree of swelling or inflow of H2O is controlled by the osmotic pressure balance between the gallery and the solution environment, both of which are relatively independent of electrolyte identity but substantially dependent on molarity. In solutions of tertiary amines and quaternary ammonium hydroxides, the uptake of ammonium ions increases nearly linearly with increasing external concentration before reaching a saturation plateau, i.e., ~40% relative to the cation-exchange capacity of the crystals used. The only exception is tetrabutylammonium ions, which yield a lower saturation value, ~30%, owing to steric effects. The swelling behaviors in some primary amine solutions differ as a result of the effect of attractive forces between amine solute molecules on the solution osmotic pressure. Although the swelling is essentially colligative in nature, the stability of the resultant swollen structure is heavily dependent on the chemical nature of the guest ions. Intercalated ions of higher polarity and smaller size help stabilize the swollen structure, whereas ions of lower polarity and larger size lead readily to exfoliation. The insight gained from this study sheds new light on both the incorporation of guest molecules into a gallery of layered structures in general and the exfoliation of materials into elementary single-layer nanosheets. PMID:24635385

Geng, Fengxia; Ma, Renzhi; Ebina, Yasuo; Yamauchi, Yusuke; Miyamoto, Nobuyoshi; Sasaki, Takayoshi

2014-04-01

274

Imaging Fourier transform spectroscopy of the boundary layer plume from laser irradiated polymers and carbon materials  

Science.gov (United States)

The high-energy laser (HEL) lethality community needs for enhanced laser weapons systems requires a better understanding of a wide variety of emerging threats. In order to reduce the dimensionality of laser-materials interaction it is necessary to develop novel predictive capabilities of these events. The objective is to better understand the fundamentals of laser lethality testing by developing empirical models from hyperspectral imagery, enabling a robust library of experiments for vulnerability assessments. Emissive plumes from laser irradiated fiberglass reinforced polymers (FRP), poly(methyl methacrylate) (PMMA) and porous graphite targets were investigated primarily using a mid-wave infrared (MWIR) imaging Fourier transform spectrometer (FTS). Polymer and graphite targets were irradiated with a continuous wave (cw) fiber lasers. Data was acquired with a spectral resolution of 2 cm-1 and spatial resolution as high as 0.52 mm2 per pixel. Strong emission from H2O, CO, CO2 and hydrocarbons were observed in the MWIR between 1900-4000 cm-1. A single-layer radiative transfer model was developed to estimate spatial maps of temperature and column densities of CO and CO2 from the hyperspectral imagery of the boundary layer plume. The spectral model was used to compute the absorption cross sections of CO and CO2, using spectral line parameters from the high temperature extension of the HITRAN. Also, spatial maps of gas-phase temperature and methyl methacrylate (MMA) concentration were developed from laser irradiated carbon black-pigmented PMMA at irradiances of 4-22 W/cm2. Global kinetics interplay between heterogeneous and homogeneous combustion kinetics are shown from experimental observations at high spatial resolutions. Overall the boundary layer profile at steady-state is consistent with CO being mainly produced at the surface by heterogeneous reactions followed by a rapid homogeneous combustion in the boundary layer towards buoyancy.

Acosta, Roberto I.

275

Development of nano cerium oxide incorporated aluminium alloy sacrificial anode for marine applications  

International Nuclear Information System (INIS)

Aluminium-zinc alloy sacrificial anodes are extensively used for cathodic protection. The performance of the sacrificial anodes can be significantly improved by incorporation of microalloying elements in the aluminium matrix. In the present work nano cerium oxide particles of different concentrations, ranging from 0 to 1 wt% were incorporated for activating and improving the performance of the anode. The electrochemical test results revealed the increased efficiency of the anode. The electrochemical impedance spectroscopy revealed the information that the presence of nano cerium oxide in the anode matrix caused effective destruction of the passive alumina film, which facilitated enhancement of galvanic performance of the anode. Moreover, the biocidal activity of cerium oxide prevented the bio accumulation considerably which enables the anodes to be used in aggressive marine conditions

276

Sacrificial Microchannel Sealing by Glass-Frit Reflow for Chip Scale Atomic Magnetometer  

Science.gov (United States)

A novel sealing technique using sacrificial microchannels was proposed for atmosphere control in a micromachined alkali gas-filled cell for a chip scale atomic magnetometer. The microchannels act as feedthrough connecting the cell to outside atmosphere during evacuation and gas-filling steps, and eventually they are sealed by glass-frit reflow. Si microchannel dedicated as a sacrificial microchannel was proposed and its feasibility was successfully demonstrated by experiments. The simulation results clarified the glass-frit reflow characteristics and its dependence on cross-sectional shape of the microchannel. Hermeticity of the proposed sealing technique of less than 10-12Pa·m3/s leak rate was verified by a high resolution helium leak test.

Tsujimoto, Kazuya; Hirai, Yoshikazu; Sugano, Koji; Tsuchiya, Toshiyuki; Tabata, Osamu

277

Magnesium-Based Sacrificial Anode Cathodic Protection Coatings (Mg-Rich Primers) for Aluminum Alloys  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Magnesium is electrochemically the most active metal employed in common structural alloys of iron and aluminum. Mg is widely used as a sacrificial anode to provide cathodic protection of underground and undersea metallic structures, ships, submarines, bridges, decks, aircraft and ground transportation systems. Following the same principle of utilizing Mg characteristics in engineering advantages in a decade-long successful R&D effort, Mg powder is now employed in organic coatings (termed ...

Blanton, Michael D.; Rawlins, James W.; Pathak, Shashi S.; Mendon, Sharathkumar K.

2012-01-01

278

Long-term performance of different aluminum alloy designs as sacrificial anodes for rebars  

Digital Repository Infrastructure Vision for European Research (DRIVER)

This paper presents the performance of various cathodic-protection designs using Aluminum alloys to protect prestressed piles. The results obtained with different system designs (bracelete type-Al/Zn/In alloy, thermosprayed aluminum (3-year evaluation) and conventional Al/Zn/In anocies in an epoxy-painted steel bracelet (12-year evaluation)), indicated that all of these systems may be used as sacrificial anodes for pile protection. However, the thermosprayed aluminum type can not be used in p...

Rinco?n, O.; Sa?nchez, M.; Romero, M.; Paz, G.; Campos, W.

2003-01-01

279

Roles of hydrophilicities and hydrophobicities of dye and sacrificial electron donor on the photochemical pathway  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Relative rates of the photosensitized production of singlet oxygen (1O2) and of superoxide (O2•?) were determined using different couples of dyes and sacrificial electron donors (SEDs) of either high or low hydrophobicities. Such rates were also measured in the absence and presence of single unilamellar vesicles (SUVs) with 9DMPC:1DMPA mol ratio composition. The dyes aluminum phthalocyanine tetrasulfonate (AlPcS4) and pheophorbide-a (PHEO) were used as hydrophilic and hydrophobic photosen...

Sanchez-cruz, Pedro; Dejesus-andino, Francisco; Alegria, Antonio E.

2012-01-01

280

‘Utilitarian’ judgments in sacrificial moral dilemmas do not reflect impartial concern for the greater good  

Science.gov (United States)

A growing body of research has focused on so-called ‘utilitarian’ judgments in moral dilemmas in which participants have to choose whether to sacrifice one person in order to save the lives of a greater number. However, the relation between such ‘utilitarian’ judgments and genuine utilitarian impartial concern for the greater good remains unclear. Across four studies, we investigated the relationship between ‘utilitarian’ judgment in such sacrificial dilemmas and a range of traits, attitudes, judgments and behaviors that either reflect or reject an impartial concern for the greater good of all. In Study 1, we found that rates of ‘utilitarian’ judgment were associated with a broadly immoral outlook concerning clear ethical transgressions in a business context, as well as with sub-clinical psychopathy. In Study 2, we found that ‘utilitarian’ judgment was associated with greater endorsement of rational egoism, less donation of money to a charity, and less identification with the whole of humanity, a core feature of classical utilitarianism. In Studies 3 and 4, we found no association between ‘utilitarian’ judgments in sacrificial dilemmas and characteristic utilitarian judgments relating to assistance to distant people in need, self-sacrifice and impartiality, even when the utilitarian justification for these judgments was made explicit and unequivocal. This lack of association remained even when we controlled for the antisocial element in ‘utilitarian’ judgment. Taken together, these results suggest that there is very little relation between sacrificial judgments in the hypothetical dilemmas that dominate current research, and a genuine utilitarian approach to ethics. PMID:25460392

Kahane, Guy; Everett, Jim A.C.; Earp, Brian D.; Farias, Miguel; Savulescu, Julian

2015-01-01

 
 
 
 
281

Thermal response of infinitely extended layered nickel-titanium shape memory alloy thin film with variable material properties  

Science.gov (United States)

This paper reports a study of the thermal response of an infinitely extended shape memory alloy thin film. Motivated by experiments reported in the literature about SMA thin films on a silicon substrate, the thin film is taken to have three layers from the bottom to the top - an amorphous layer, a non-transforming austenitic layer and a transforming SMA layer. The boundary conditions are taken to be adiabatic and convective at the bottom of the film and the top respectively. The material properties of the transforming layer (thermal conductivity, electrical resistivity and specific heat) are taken to evolve hysteretically with temperature, commencing from an initial room temperature state of martensite. All the results are presented in non-dimensional form. The steady state results are compared with an analytical solution. The computations of the transient response are carried out with ANSYS. The thermal response of the 3-layer model is compared with that of a 1-layer model (where the entire film is a SMA transforming layer) and it is seen that the the temperature of the top surface for the 3-layer model is higher than that of the 1-layer model. It is also seen that the evolution of the specific heat has the least effect whereas the evolution of the electrical resistivity has the most effect on the thermal response of the 3-layer model. The thermal response of the infinitely extended films provides a benchmark against which the response of finite sized films can be assessed.

Bhattacharyya, Abhijit; Ozturk, Mehmet Mete

2013-04-01

282

Fluorine uptake into the human tooth from a thin layer of F-releasing material  

Energy Technology Data Exchange (ETDEWEB)

Using the proton induced gamma-ray emission (PIGE) method (TIARA, Japan), we have studied fluorine (F) distribution in the human tooth under various conditions. Here, we report F uptake into the human tooth from a thin layer of F-releasing low viscous resin (FLVR). Crowns of human teeth were horizontally cut and the dentin of the cut surface was first covered with four kinds of FLVR (FL-Bond, Reactmer Bond, Xeno Bond, and Protect Liner F; thickness, 50-150 {mu}m) according to the manufacturers' instructions. Non-F-releasing and F-releasing filling resins were also hardened, on the cut surfaces of crowns covered with four kinds of FLVR thin layers. The type of the non-F-releasing filling materials used was LITE FIL IIP: G1-A (FL-Bond and LITE FIL IIP), G2-A (Reactmer Bond and LITE FIL IIP), G3-A (Xeno Bond and LITE FIL IIP), and G4-A (Protect Liner F and LITE FIL IIP). The types of F-releasing filling materials used were G1-B (FL-Bond and Beautifil), G2-B (Reactmer Bond and Reactmer Paste), G3-B (Xeno Bond and Xeno CF Paste), and G4-B (Protect Liner F and Teethmate F-1). Treatment and measurements of specimens were the same as previously reported [H. Yamamoto, M. Nomahci, K. Yasuda, Y. Iwami, S. Ebisu, N. Yamamoto, T. Sakai, T. Kamiya, Nucl. Instr. and Meth. B 210 (2003) 388]. F uptake from specimens following one month of application was estimated from 2-D maps. F penetration was observed in all teeth of G1-A-G4-A groups. The maximum values of F concentration in each tooth and F penetration depth were larger for larger F concentrations in FLVR. FLVR was useful for the F uptake into the tooth, and the F distribution near the thin layer of FLVR depended on the materials used. Between G1-A and G1-B or G4-A and G4-B, the F uptake was significantly different. We were able to obtain fundamental data, which were useful for the analysis of F transportation relating to prevention of caries.

Yamamoto, H. [Department of Restorative Dentistry and Endodontology, Graduate School of Dentistry, Osaka University, 1-8 Yamadaoka, Suita, Osaka, 565-0871 (Japan)]. E-mail: yhiroko@dent.osaka-u.ac.jp; Nomachi, M. [Graduate School of Science, Osaka University, Toyonaka, Osaka, 560-0043 (Japan); Yasuda, K. [Wakasa Wan Energy Research Center, Tsuruga, Fukui, 914-0192 (Japan); Iwami, Y. [Department of Restorative Dentistry and Endodontology, Graduate School of Dentistry, Osaka University, 1-8 Yamadaoka, Suita, Osaka, 565-0871 (Japan); Ebisu, S. [Department of Restorative Dentistry and Endodontology, Graduate School of Dentistry, Osaka University, 1-8 Yamadaoka, Suita, Osaka, 565-0871 (Japan); Komatsu, H. [Graduate School of Dental Medicine, Hokkaido University, Sapporo, Hokkaido, 060-8585 (Japan); Sakai, T. [Advanced Radiation Technology Center, JAERI, Takasaki, Gunma, 370-1292 (Japan); Kamiya, T. [Advanced Radiation Technology Center, JAERI, Takasaki, Gunma, 370-1292 (Japan)

2007-07-15

283

The effect of gamma-irradiation on few-layered graphene materials  

Science.gov (United States)

The effect of ?-irradiation on the structure and composition of chemically synthesized few-layered graphene materials was studied. Fully oxidized graphene oxide and graphene nanoribbons, as well as their respective chemically post-reduced forms, were treated under ?-irradiation in an air-sealed environment. Three different irradiation doses of 60, 90 and 150 kGy were applied. Structure and composition of the irradiated materials were analyzed by X-ray diffraction (XRD), Fourier-transform infrared spectroscopy (FTIR), thermogravimetric analysis (TGA), Raman spectroscopy and X-ray photoelectron spectroscopy (XPS). The XRD patterns were not affected by ?-irradiation, and small changes were observed in the FTIR and TGA results. However, significant modifications were detected by Raman spectroscopy and XPS, particularly in the Raman G/D band intensity ratios and in the C 1s XPS profiles. Comparatively, the changes in Raman and XPS spectra after ?-irradiation were even greater than those occurring during the chemical reduction of graphene oxides. Our results indicate that the graphene carbon lattice was strongly affected by ?-irradiation, but the materials experienced small variations in their oxygen content.

Ansón-Casaos, A.; Puértolas, J. A.; Pascual, F. J.; Hernández-Ferrer, J.; Castell, P.; Benito, A. M.; Maser, W. K.; Martínez, M. T.

2014-05-01

284

Photon tunneling and transmittance resonance through a multi-layer structure with a left-handed material  

International Nuclear Information System (INIS)

This paper investigates the photon tunneling and transmittance resonance through a multi-layer structure including a left-handed material(LHM). An analytical expression for the transmittance in a five-layer structure is given by the analytical transfer matrix method. The transmittance is studied as a function of the refractive index and the width of the LHM layer. The perfect photon tunneling results from the multi-layer structure, especially from the relation between the magnitude of the refractive index and the width of the LHM layer and those of the adjoining layers. Photons may tunnel through a much greater distance in this structure. Transmittance resonance happens, the peaks and valleys appear periodically at the resonance thickness. For an LHM with inherent losses, the perfect transmittance is suppressed. (electromagnetism, optics, acoustics, heat transfer, classical mechanics, and fluid dynamics)

285

Synthesis of polyaniline/carbon black hybrid hollow microspheres by layer-by-layer assembly used as electrode materials for supercapacitors  

International Nuclear Information System (INIS)

Graphical abstract: The polyaniline/carbon black hybrid hollow microspheres with a external diameter about 3.0 ?m were prepared via layer-by-layer assembly technique, and the electrochemical tests showed that polyaniline/carbon black hybrid hollow microspheres would be a potential candidates of electrode materials for supercapacitors with high specific capacitance. Highlights: ? The PAn/CB hybrid hollow microspheres were prepared via LBL technique. ? The specific capacitance increased with the increase in the adsorption of PAn and CB. ? The hollow structure and synergistic effect of shell enhance the specific capacitance. ? The PAn/CB hollow microsphere is a candidate of electrode material for supercapacitor. -- Abstract: The polyaniline (PAn)/carbon black (CB) hybrid hollow microspheres have been prepared by the layer-by-layer assembly technique alternately adsorbing of PAn and CB onto the polystyrene sulfonate microsphere templates after etching the templates by dialysis. The hollow structure of the obtained hybrid hollow microspheres was characterized by transmission electron microscopy, which indicated that the external diameter of the hollow microspheres was about 3.0 ?m. When the hybrid hollow microsphere were used as the electrode material for supercapacitors, the results showed that the specific capacitance increased with the increase in the adsorption numbers of PAn and CB, which was as high as 532 F g?1 at a charge–discharge current density of 10 mA cm?2 in 1.0 M H2SO4 electrolyte after alternately adsorbing of PAn and CB six times

286

Non-destructive characterization of surface layers on non ferromagnetic materials  

International Nuclear Information System (INIS)

Electromagnetic nondestructive techniques are usually applied to solve many inspection problems in industry. In particular, eddy currents are used for the detection of defects and the characterization of physical properties of metallic materials and components. One such application is the measurement of thickness of non conductive layers on a conducting substrate. A laboratory device for the quantitative determination of those thicknesses was developed at our laboratory. It works in the range from 0 to 100 ?m and was calibrated with a micro metre screw. This task involved the design and construction of the sensors their characterization (working frequency, resolution, sensitivity, etc.) and the setup of the mechanical system and the electronic signal generation and measurement circuit. (author)

287

Improved description of soft layered materials with van der Waals density functional theory  

Science.gov (United States)

The accurate description of van der Waals forces within density functional theory is currently one of the most active areas of research in computational physics and chemistry. Here we report results on the structural and energetic properties of graphite and hexagonal boron nitride, two layered materials where interlayer binding is dominated by van der Waals forces. Results from several density functionals are reported, including the optimized Becke88 van der Waals (optB88-vdW) and the optimized PBE van der Waals (optPBE-vdW) (Klimeš et al 2010 J. Phys.: Condens. Matter 22 022201) functionals. Where comparison to experiment and higher-level theory is possible, the results obtained from the two new van der Waals density functionals are in good agreement. An analysis of the physical nature of the interlayer binding in both graphite and hexagonal boron nitride is also reported.

Graziano, Gabriella; Klimeš, Ji?í; Fernandez-Alonso, Felix; Michaelides, Angelos

2012-10-01

288

The thin electrolyte layer approach to corrosion testing of dental materials--characterization of the technique.  

Science.gov (United States)

An innovative technique for corrosion testing of metallic dental materials is introduced. The thin electrolyte layer technique (TET) simulates the physical characteristics of the oral environment by employing a still, thin layer of an electrolyte, in contrast to bulk electrolyte techniques (BET) which utilize relatively large quantities of fluid. Limiting current density tests on a platinum electrode revealed a lower surface oxygen content for TET. Borate buffer (pH 6.8) was employed as an electrolyte. The effect of lower oxygen content in TET on passivation and polarization characteristics of 316L SS in 0.9% saline was investigated. The results revealed differences in the polarization resistance and open circuit potential development with time, as well as in anodic and cathodic polarization behavior. Lower O2 concentration in TET was attributed to different electrolyte convection characteristics under both testing conditions. Additionally, use of the TET resulted in better data reproducibility. Overall, this investigation led to a deeper understanding of the electrochemical processes inherent in thin electrolytes such as those found in the oral environment. PMID:9884061

Ledvina, M; Rigney, E D

1998-12-01

289

SeP hole injection layer for devices based on organic materials  

Science.gov (United States)

Selenium?:?phosphour (SeP) thin films produced by thermal sublimation in vacuum are used as hole injection layers (HILs) in tris(8-hydroxyquinolinato) aluminum (Alq3) based devices. These devices are constructed in the sandwich structure substrate/HIL/Alq3/Al using three different substrate electrodes: fluorine doped tin oxide, Au, and indium tin oxide. The obtained electrical measurements indicate a better injection of positive charge carriers using the SeP layer. Syncrotron radiation x-ray photoelectron experiments allowed the determination of the work function of SeP. The obtained value (? = 5.6 eV) is close to the HOMO energy level of Alq3 and is consistent with the better positive charge injection. The thermionic injection process is suggested to be responsible for the charge injection from the different substrate electrodes into the SeP material. From transmittance measurements it was possible to calculate the refractive index and absorption coefficient as a function of wavelength, and to estimate the optical band gap (Eg = 1.9 eV). The latter and the measured work function were used in the construction of an energy level diagram of the SeP thin films used as HILs in organic devices. The hole injection efficiency of the produced films are compared with results using poly(3,4-ethylenedioxythiophene) poly(styrenesulfonate) (PEDOT?:?PSS).

Serbena, J. P. M.; Machado, K. D.; Siqueira, M. C.; Hümmelgen, I. A.; Mossanek, R. J. O.; de Souza, G. B.; da Silva, J. H. D.

2014-01-01

290

A WOOD REPLACEMENT MATERIAL OF SANDWICH STRUCTURE USING COIR FIBER MATS AND FIBERGLASS FABRICS AS CORE LAYER  

Digital Repository Infrastructure Vision for European Research (DRIVER)

The tensile strength and bending strength of natural coir fiber are lower than many other natural fibers. Therefore, coir fiber is unsuitable for many fiber reinforcement applications. This study exploits the better shock resistance and toughness of coir fiber, which suggest that coir fiber can be used as a type of replacement material in plywood. Fast-growing poplar was chosen as the surface material, and coir fiber was selected as the core layer material for their buffering ability and toug...

Jia Yao,; Ying Cheng Hu,; Wei Lu

2011-01-01

291

The behaviour of selected material/oxide layer systems with change of temperature loading  

International Nuclear Information System (INIS)

In this work, the behaviour of material/oxide layer systems with isothermal and thermal cycling stresses was examined in detail on the example of X 20 CrMoV 12 1, alloy 800 H (X 10 NiCrAlTi 32 20) and HK 40 (G-X 40 CrNiSi 25 20) steels. The materials were in the form of heat exchanger pipes and some of them were bar material. The change of temperature loading was defined by the parameter temperature of the isothermal stopping phase, maximum cooling load, duration of the isothermal stopping phase and the value of the cooling speed. The parameters for the individual materials were as follows: X 20 CrMoV 12 1:650deg C, 350deg-250deg C, 4-24 hours, 10degC/min; Alloy 800 H: 900degC, 650deg-800deg C, 12-48 hours, 25degC/min; HK 40: 950deg C, 750deg C, 12-48 hours, 25degC/min. The compliance of the parameters was controlled by a personal computer, which was used to record sound emission measurements. The analysis of sound signals on the heat exchanger pipes, similar to components, or on bars should give information on the time of occurrence and the type of oxidation damage. The experiments were carried out in air, air + 0.5% SO2 and for X 20 CrMoV 12 1 also with an (Ar + 5% H2) + 50% H2O gas mixture on the inside of the heat exchanger pipes. (orig./MM)

292

In Situ XRD Investigations on Structural Change of P2-Layered Materials during Electrochemical Sodiation/Desodiation  

DEFF Research Database (Denmark)

Sodium layered oxides (NaxMO2) are attractive as positive electrode materials for rechargeable sodium-ion batteries (SIBs) due to high capacity, fast ionic diffusion and simple synthetic process. O3-layered lithium compounds have led successful commercialization of current lithium-ion batteries; as a result, rich experiences for structural studies of O3-layered compounds have been accumulated over the past decades. For sodium layered oxides, however, P2-layered compounds have been reported for better cyclability and structural stability during electrochemical reactions than O3-structure. Therefore, systematic studies on P2-layered materials for SIBs are highly required. In this study, we report the structural and electrochemical property of P2-NaxFeyMnyCo1-2yO2 synthesized by simple solid state reaction. The X-ray diffraction pattern of as-synthesized powder is indexed as a hexagonal lattice (P63/mmc, No.194), which is identical to P2-layered structure. The structural changes in hexagonal P2-layered oxides have been investigated during electrochemical sodiation/desodiation by in-situ synchrotron X-ray diffractions of a capillary based micro battery cell. From the result of in-situ studies, the initial layered structure is maintained from 2.0 to 4.0 V vs. Na+/Na during first desodiation. The phase transformation is observed over the 4.0 V, but the original P2 structure is completely restored at the following sodiation process. The relationship between structural and electrochemical properties of this P2-layered material will be discussed.

Jung, Young Hwa; Johnsen, Rune E.

2014-01-01

293

Formation of accessory mineral bed layers during erosion of bentonite buffer material  

International Nuclear Information System (INIS)

Document available in extended abstract form only. dilute groundwater at a transmissive fracture interface, accessory phases within bentonite, such as quartz, feldspar, etc., might remain behind and form a filter bed or cake. As more and more montmorillonite is lost, the thickness of the accessory mineral bed increases and the continued transport of montmorillonite slows and possibly stops if the porosity of the filter bed is sufficiently compressed. Alternatively or concurrently, as the accessory mineral filter bed retains montmorillonite colloids, a filter cake composed of montmorillonite itself may be formed. Ultimately, depending on their extent, properties, and durability, such processes may provide the bentonite buffer system with an inherent, self-filtration mechanism which serves to limit the effects of colloidal erosion. A conceptual view of bentonite buffer extrusion and erosion in an intersecting fracture with formation of an accessory mineral filter bed and montmorillonite filter cake is presented in Figure 1. Due to the swelling pressure of the bentonite buffer, the situation described in Figure 1 may be analogous to that of the case of pressure filtration where a filter cake is formed by pressing a suspension through a filter medium and, by a mechanism known as expression, the filter cake is compressed by direct contact with a solid surface resulting in a reduction of its porosity. In order to examine whether the erosion of bentonite material through con erosion of bentonite material through contact with dilute groundwater at a transmissive fracture interface could intrinsically result in 1) the formation of an accessory mineral filter bed and cake and/or 2) filter caking of montmorillonite itself, a series of laboratory tests were performed in a flow-through, horizontal, 1 mm aperture, artificial fracture system. Bentonite buffer material was simulated by using mixtures (75/25 weight percent ratio) of purified sodium montmorillonite and various additives serving as accessory mineral proxies (kaolin, quartz sand, chromatographic silica). The resulting mixtures were compacted into dense sample tablets with effective montmorillonite dry densities between 1.4 to 1.6 g/cm3. The fracture erosion tests were performed using a Grimsel groundwater simulant (relative to Na+ and Ca2+ concentration only) contact solution at an average flow rate of 0.09 ml/min through the system. In colloid filtration theories, the filter bed is modelled as an assemblage of single or unit collectors having a known geometry. According to Richards [2010], the particle size distribution of the accessory minerals in MX-80 bentonite consists of particles with sizes less than 30 ?m. Of the additive materials used in this study, the kaolin material consists of particles with sizes less than 20 ?m showing a peak size of 6 ?m, the chromatographic silica consists of particles with sizes narrowly distributed between 10 to 14 ?m, and the sand consists of particles with sizes between 160 to 550 ?m at a peak size of 280 ?m. The tests were designed to lead to the development of erosive conditions (i.e., sodium montmorillonite against a dilute solution) and, in every case, the formation of an accessory mineral bed layer near the extrusion/erosion interface was observed. Moreover, these layers grew progressively in thickness over the course of the tests. These results provide evidence that, following erosive loss of colloidal montmorillonite through contact with dilute groundwater at a transmissive fracture interface, accessory phases (within bentonite) remain behind and form bed layers

294

Tube Formation in Nanoscale Materials  

Directory of Open Access Journals (Sweden)

Full Text Available Abstract The formation of tubular nanostructures normally requires layered, anisotropic, or pseudo-layered crystal structures, while inorganic compounds typically do not possess such structures, inorganic nanotubes thus have been a hot topic in the past decade. In this article, we review recent research activities on nanotubes fabrication and focus on three novel synthetic strategies for generating nanotubes from inorganic materials that do not have a layered structure. Specifically, thermal oxidation method based on gas–solid reaction to porous CuO nanotubes has been successfully established, semiconductor ZnS and Nb2O5nanotubes have been prepared by employing sacrificial template strategy based on liquid–solid reaction, and an in situ template method has been developed for the preparation of ZnO taper tubes through a chemical etching reaction. We have described the nanotube formation processes and illustrated the detailed key factors during their growth. The proposed mechanisms are presented for nanotube fabrication and the important pioneering studies are discussed on the rational design and fabrication of functional materials with tubular structures. It is the intention of this contribution to provide a brief account of these research activities.

Yan Chenglin

2008-01-01

295

Low Concentration of Iron as First Wall Material in LHD Plasmas with Edge Ergodic Layer  

International Nuclear Information System (INIS)

Full text: Experiments of Large Helical Device (LHD) have been successfully conducted during past 14 years, based on the first wall fully covered with rectangular protection plates made of stainless steel, basically having no serious impurity problem. The impurity behavior of iron has been quantitatively studied with a spectroscopic system newly developed for measuring two-dimensional distribution of extreme-ultraviolet (EUV) impurity lines. The iron density in core plasmas is found to be fairly low, at least five orders of magnitude smaller than the electron density. The highest density of iron is observed during impurity accumulation triggered by pellet injection. The central density of Fe23+ ions analyzed from FeXXIV profile reaches 2.6 x 109 cm-3 during the impurity accumulation phase with appearance of a large inward convective velocity of V = - 6 m/s, whereas it is only 3 x 108 cm-3 before the accumulation occurs. No accumulation is observed for light impurities. The accumulation is mainly caused by the density gradient. These results are very similar to tokamak ones, but only the value of the iron density is different between tokamaks and LHD. The stochastic magnetic filed layer of LHD can effectively fulfill its function as the impurity screening in collisional regime of 10 K /Lee K is the Kolmogolov length and Lee the electron mean free path. Inb>ee the electron mean free path. In 3D edge transport simulation the impurity screening is observed in the edge boundary region, where the LK is nearly 10 m. The iron with slower velocity is ionized at outer region of the stochastic layer where the parallel thermal gradient (i.e., thermal force) is smaller. Therefore, larger values of LK /Lee for heavier ions like iron enhance the friction force along magnetic filed, leading to an efficient impurity screening. In LHD the radiation loss from iron is smaller than 1 MW in usual discharges (PNBI = 20 - 30 MW), which is often comparable to radiation from carbon originated in divertor plates. These transport processes interacted with magnetic field structure are of primal reason why the density of iron impurity is fairly low in LHD. The screening effect developed in edge stochastic layer intrinsically existing in LHD works well for materials of the first wall. The present result strongly suggests tolerant use of high-Z materials to the first wall of LHD-type reactor. (author)

296

Thermal Stability of Gold Nanoparticles Embedded within Metal Oxide Frameworks Fabricated by Hybrid Modifications onto Sacrificial Textile Templates.  

Science.gov (United States)

The stability and spatial separation of nanoparticles (NP's) is essential for employing their advantageous nanoscale properties. This work demonstrates the entrapment of gold NP's embedded in a porous inorganic matrix. Initially, gold NP's are decorated on fibrous nylon-6, which is used as an inexpensive sacrificial template. This is followed by inorganic modification using a novel single exposure cycle vapor phase technique resulting in distributed NP's embedded within a hybrid organic-inorganic matrix. The processing is extended to the synthesis of porous nanoflakes after calcination of the modified nylon-6 yielding a porous metal oxide framework surrounding the disconnected NP's with a surface area of 250 m(2)/g. A unique feature of this work is the use of a transmission electron microscope (TEM) equipped with an in situ annealing sample holder. The apparatus affords the opportunity to explore the underlying nanoscopic stability of NP's embedded in these frameworks in a single step. TEM analysis indicates thermal stability up to 670 °C and agglomeration characteristics thereafter. The vapor phase processes developed in this work will facilitate new complex NP/oxide materials useful for catalytic platforms. PMID:25557142

Padbury, Richard P; Halbur, Jonathan C; Krommenhoek, Peter J; Tracy, Joseph B; Jur, Jesse S

2015-01-27

297

Laser etching of transparent materials at a backside surface adsorbed layer  

International Nuclear Information System (INIS)

The laser etching using a surface adsorbed layer (LESAL) is a new method for precise etching of transparent materials with pulsed UV-laser beams. The influence of the processing parameters to the etch rate and the surface roughness for etching of fused silica, quartz, sapphire, and magnesium fluoride (MgF2) is investigated. Low etch rates of 1 nm/pulse and low roughness of about 1 nm rms were found for fused silica and quartz. This is an indication that different structural modifications of the material do not affect the etching significantly as long as the physical properties are not changed. MgF2 and sapphire feature a principal different etch behavior with a higher etch rate and a higher roughness. Both incubation effects as well as the temperature dependence of the etch rate can be interpreted by the formation of a modified near surface region due to the laser irradiation. At repetition rates up to 100 Hz, no changes of the etch rate have been observed at moderate laser fluences

298

Effect of the number of graded layers on the microstructure and properties of SiC/C functionally graded materials  

International Nuclear Information System (INIS)

SiC/C bulk functionally graded materials (FGMs) with different numbers of graded layers (N) for fusion technology were designed and fabricated successfully by a power stacking method and hot-pressing process under the pressure of 30 MPa at 2000 deg. C. Results showed that the number of graded layers (N) had marked effect on the microstructure and properties of the as-received SiC/C FGMs. SEM examinations indicated that interfaces between the adjacent layers faded out gradually and became more linearly continuous gradient with increasing number of graded layers, which led to marked improvement in the bend strength and thermal shock resistance of the samples. Water quenching tests with a temperature difference of 500 deg. C showed that SiC/C FGMs with N > 8 had the best thermal shock resistance for the materials studies, and no cracks occurred after 90 quench cycles

299

Comparative Study of Charge Trapping Type SOI-FinFET Flash Memories with Different Blocking Layer Materials  

Directory of Open Access Journals (Sweden)

Full Text Available The scaled charge trapping (CT type silicon on insulator (SOI FinFET flash memories with different blocking layer materials of Al2O3 and SiO2 have successfully been fabricated, and their electrical characteristics including short-channel effect (SCE immunity, threshold voltage (Vt variability, and the memory characteristics have been comparatively investigated. It was experimentally found that the better SCE immunity and a larger memory window are obtained by introducing a high-k Al2O3 blocking layer instead of a SiO2 blocking layer. It was also confirmed that the variability of Vt before and after one program/erase (P/E cycle is almost independent of the blocking layer materials.

Yongxun Liu

2014-06-01

300

Protective or damage promoting effect of calcium carbonate layers on the surface of cement based materials in aqueous environments  

International Nuclear Information System (INIS)

Cement based materials permanently exposed to aggressive aqueous environments are subject to chemical changes affecting their durability. However, this holds also for tap water that is considered to be not aggressive to cementitious materials, although in that case a formation of covering layers of CaCO3 on the alkaline surfaces is commonly supposed to provide protection against reactive transport processes. Thus, investigations of the structural and chemical properties of the material/water interface were carried out in laboratory experiments and case studies to elucidate the consequences of surface reactions for the durability of cement based materials exposed to tap water. Focused Ion Beam investigations revealed that a protective effect of a CaCO3 covering layer depends on its structural properties, which are in turn affected by the hydro-chemical conditions during crystallization. Surface precipitation of CaCO3 can trigger further chemical degradation, if the required calcium is supplied by the pore solution of the material.

 
 
 
 
301

Dependences of optical properties of spherical two-layered nanoparticles on parameters of gold core and material shell  

International Nuclear Information System (INIS)

Modeling of nonlinear dependences of optical properties of spherical two-layered gold core and some material shell nanoparticles (NPs) placed in water on parameters of core and shell was carried out on the basis of the extended Mie theory. Efficiency cross-sections of absorption, scattering and extinction of radiation with wavelength 532 nm by core–shell NPs in the ranges of core radii r00=5–40 nm and of relative NP radii r1/r00=1–8 were calculated (r1—radius of two-layered nanoparticle). Shell materials were used with optical indexes in the ranges of refraction n1=0.2–1.5 and absorption k1=0–3.5 for the presentation of optical properties of wide classes of shell materials (including dielectrics, metals, polymers, vapor shell around gold core). Results show nonlinear dependences of optical properties of two-layered NPs on optical indexes of shell material, core r00 and relative NP r1/r00 radii. Regions with sharp decrease and increase of absorption, scattering and extinction efficiency cross-sections with changing of core and shell parameters were investigated. These dependences should be taken into account for applications of two-layered NPs in laser nanomedicine and optical diagnostics of tissues. The results can be used for experimental investigation of shell formation on NP core and optical determination of geometrical parameters of core and shell of two-layered NPs. -- Highlights: • Absorption, scattering and extinction of two-layered nanoparticles are studied. • Shell materials change in wide regions of materials (metals, dielectrics, vapor). • Effect of sharp decrease and increase of optical characteristics is established. • Explanation of sharp decreasing and increasing optical characteristics is presented

302

Design, materials and R and D issues of innovative thermal contact joints for high heat flux applications  

International Nuclear Information System (INIS)

Plasma facing components in fusion machines are designed with a layer of sacrificial armour material facing the plasma and a high-conductivity material in contact with the coolant. One of the most critical issues associated with making the proposed design concept work, from a power handling point of view, is achieving the necessary contact conductance between the armour and the heat sink.This paper presents a novel idea for the interface joint between the sacrificial armour and the actively cooled permanent heat sink. It consists of a thermal bond layer of a binary or more complex alloy, treated in the semi-solid region in such a way as to lead to a fine dispersion of a globular solid phase into a liquid matrix (rheocast process). The alloy in this ''mushy state'' exhibits a time-dependent, shear rate-dependent viscosity, which is maintained reversibly when the material is solidified and heated again in the semi-solid state. The function of the thermal bond layer is to facilitate heat transfer between the replaceable armour and the permanent heat sink without building up excessive thermal stresses, as in conventional brazed joints, and allow an easy replacement whenever needed without disturbing the coolant system. No contact pressure is required in this case to provide the desired heat transfer conductance, and the reversible thixotropic properties of the rheocast material should guarantee the stability of the layer in the semi-solid conditions.Key design, material ami-solid conditions.Key design, material and testing issues are identified and discussed in this paper with emphasis on specific needs for future research and development work. Examples of suitable material options which are being considered are reported together with some initial heat transfer analysis results. (orig.)

303

Magnetic, thermoelectric, and electronic properties of layered oxides and carbon materials  

Science.gov (United States)

The structure and physical properties of layered oxides and carbon materials were studied. Two layered carbon materials were studied: carbon nanotubes (CNTs) synthesized by electron irradiation from amorphous carbon in situ in a transmission electron microscope (TEM) and a carbon and silver nanocomposite consisting of graphitic carbon nanospheres encapsulating Ag nanoparticles. In the CNT experiments, the effect of electron irradiation in the TEM is shown to alter drastically their structure and properties, even being able to transform amorphous carbon into a CNT. This suggests a possible alternative synthesis technique for the production of CNTs, in addition to providing a method for tailoring their properties. The structure and magnetic properties of the carbon and silver nanocomposite was characterized with x-ray diffraction, scanning and transmission electron microscopy techniques, and magnetic susceptibility measurements with a superconducting quantum interference device (SQUID) magnetometer. While the sp2 bonding gives a graphene sheet its mechanical properties, the p pi electrons are responsible for its electronic and magnetic properties. In a flat graphene sheet the ppi electrons are itinerant, but in a narrow ppi band. The introduction of curvature to the graphene sheets that encapsulate the Ag nanoparticles is demonstrated to narrow the ppi band sufficiently to result in "ferromagnetic" behavior. A model that is able to explain spin localization and ferrimagnetic spin-spin interactions in graphitic materials with positive curvature is presented. Layered oxides from the family of the P2 NaxCoO 2 structure were synthesized and their properties studied. Na xCoO2 has a rich phase diagram ranging form a promising Na-rich thermoelectric composition to the hydrated Na-poor composition Na 0.33CoO2 1.3H2O that is superconductive. Intermediate to these two Na compositions exists an insulating phase with x ? 0.5 that presents a variety of interesting structural, magnetic, thermoelectric, and electronic behavior. Investigations of NaxCoO 2 that probe the role of H2O in the superconductive Na 0.33CoO2 1.3H2O are presented and conclude that H2O plays a more active role than a passive lattice spacer. The relationship between Na ordering and an interesting magnetic behavior observed with chi(T) measurements of annealed NaxCoO 2 and Srx/2CoO2 samples is determined and found to correspond to a (2a x 2a) superstructure. The properties of NaxCoO2 (x?0.5) are reviewed and thermoelectric S(T) measurements are made in order to develop a model that is able to explain the salient features of the Na0.5CoO 2 (x?0.5) phase.

Caudillo, Roman

304

Laser induced forward transfer aluminum layers: Process investigation by time resolved imaging  

Science.gov (United States)

Laser induced forward transfer of an aluminum thin film on a triazene polymer as a sacrificial layer has been studied with time resolved imaging. Both side- and front-on imaging of the process give a more detailed understanding of the stability of the ejected material during flight. For high fluence ablation (800 mJ/cm2) the flyer is stable for 400 ns and gets decomposed completely when interacting with the shockwave after 1 ?s. Material detachments on the edges of the flyer are observed at an early stage of the ablation process (laser fluence (200 mJ/cm2) the flyer has the size of the ablation spot and keeps its shape for nearly 1 ?s. The back pressure of the decomposed triazene polymer bends the flyer towards the direction of flight and indications for folding are observed.

Mattle, Thomas; Shaw-Stewart, James; Schneider, Christof W.; Lippert, Thomas; Wokaun, Alexander

2012-09-01

305

Laser induced forward transfer aluminum layers: Process investigation by time resolved imaging  

International Nuclear Information System (INIS)

Highlights: ? Side- and front-on shadowgraphy. ? Aluminum flyer is ejected intact for all tested energies. ? Indications of bending of the aluminum flyer are shown. - Abstract: Laser induced forward transfer of an aluminum thin film on a triazene polymer as a sacrificial layer has been studied with time resolved imaging. Both side- and front-on imaging of the process give a more detailed understanding of the stability of the ejected material during flight. For high fluence ablation (800 mJ/cm2) the flyer is stable for 400 ns and gets decomposed completely when interacting with the shockwave after 1 ?s. Material detachments on the edges of the flyer are observed at an early stage of the ablation process (2) the flyer has the size of the ablation spot and keeps its shape for nearly 1 ?s. The back pressure of the decomposed triazene polymer bends the flyer towards the direction of flight and indications for folding are observed.

306

EFFECTIVE LAYERED MATERIALS WITH TRANZITION ZONE FROM NANOPARTICLES CREATED IN VOLUME OF COMPOSITE / ??????????? ???????? ????????? ? ?????????? ????? ?? ??????????, ????????????? ? ?????? ?????????  

Directory of Open Access Journals (Sweden)

Full Text Available The authors describe the developed energy-effective and speedy technology of three-layered monolithic products with developed specific surface area and nanostructured transition zone between layers created by hydro thermal and power field / ??????? ????????????? ????????????????? ? ?????????? ?????????? ??????????? ?????????? ??????? ? ???????? ???????? ???????????? ? ????????????????????? ?????????? ????? ????? ??????, ??????????? ????????????????? ?????

Sokov V. N. / ????? ?????? ??????????

2014-10-01

307

Multiple pass and multiple layer friction stir welding and material enhancement processes  

Science.gov (United States)

Processes for friction stir welding, typically for comparatively thick plate materials using multiple passes and multiple layers of a friction stir welding tool. In some embodiments a first portion of a fabrication preform and a second portion of the fabrication preform are placed adjacent to each other to form a joint, and there may be a groove adjacent the joint. The joint is welded and then, where a groove exists, a filler may be disposed in the groove, and the seams between the filler and the first and second portions of the fabrication preform may be friction stir welded. In some embodiments two portions of a fabrication preform are abutted to form a joint, where the joint may, for example, be a lap joint, a bevel joint or a butt joint. In some embodiments a plurality of passes of a friction stir welding tool may be used, with some passes welding from one side of a fabrication preform and other passes welding from the other side of the fabrication preform.

Feng, Zhili (Knoxville, TN) [Knoxville, TN; David, Stan A. (Knoxville, TN) [Knoxville, TN; Frederick, David Alan (Harriman, TN) [Harriman, TN

2010-07-27

308

Atomic layer deposited molybdenum nitride thin film: a promising anode material for Li ion batteries.  

Science.gov (United States)

Molybdenum nitride (MoNx) thin films are deposited by atomic layer deposition (ALD) using molybdenum hexacarbonyl [Mo(CO)6] and ammonia [NH3] at varied temperatures. A relatively narrow ALD temperature window is observed. In situ quartz crystal microbalance (QCM) measurements reveal the self-limiting growth nature of the deposition that is further verified with ex situ spectroscopic ellipsometry and X-ray reflectivity (XRR) measurements. A saturated growth rate of 2 Å/cycle at 170 °C is obtained. The deposition chemistry is studied by the in situ Fourier transform infrared spectroscopy (FTIR) that investigates the surface bound reactions during each half cycle. As deposited films are amorphous as observed from X-ray diffraction (XRD) and transmission electron microscopy electron diffraction (TEM ED) studies, which get converted to hexagonal-MoN upon annealing at 400 °C under NH3 atmosphere. As grown thin films are found to have notable potential as a carbon and binder free anode material in a Li ion battery. Under half-cell configuration, a stable discharge capacity of 700 mAh g(-1) was achieved after 100 charge-discharge cycles, at a current density of 100 ?A cm(-2). PMID:24641277

Nandi, Dip K; Sen, Uttam K; Choudhury, Devika; Mitra, Sagar; Sarkar, Shaibal K

2014-05-14

309

Crystal Chemical Concept of Arrangement and Function of Layered Superconducting Materials  

CERN Document Server

The crystal chemical concept of arrangement and function of layered superconducting materials is supposed. The concept is based on results of our investigation of crystal chemistry of HTSC cuprates, diborides AB2 and borocarbides of nickel RNi2B2C. According to these results: (1) the main role in appearance of superconductivity play the structural fragments - sandwiches A2(CuO2) in HTSC cuprates, A2(B2) in diborides and RB(Ni) in nickel borocarbides but not the separate planes of CuO2, B2 or Ni; (2) correlations between Tc and crystal chemical parameters of these sandwiches have similar character in all three classes of compounds, despite of distinction of a nature of their superconductivity. The central idea of concept consists in following: in contrast to metallic conduction, for which it is enough to provide only concentration and mobility of charge carriers, for occurrence of a superconductivity it is necessary to create in addition a space (channels) for stream of charge carriers, compression of stream o...

Volkova, L M; Magarill, S A; Herbeck, F E

2003-01-01

310

Refractory nanoporous materials fabricated using tungsten atomic layer deposition on silica aerogels  

Energy Technology Data Exchange (ETDEWEB)

We report an approach for preparing refractory nanoporous materials using high surface area silica aerogels as templates for the growth of conformal tungsten (W) coatings by atomic layer deposition (ALD). Nanoporous silica aerogel monoliths were prepared with a variety of initial pore sizes and initial densities in the range of 0.3-0.5 g/cc using porogen extraction methods. Next, W ALD using Si{sub 2}H{sub 6} and WF{sub 6} reactants at 200 Degree-Sign C was employed to coat the inner surfaces of the silica aerogels. After coating, scanning electron microscopy revealed a microstructure in which the ALD W completely encapsulated the silica aerogel micro-cells. The porosity of the aerogels was preserved during the first 10 W ALD cycles allowing the density to be controlled by adjusting the number of W ALD cycles to achieve densities as high as 5 g/cc. Nitrogen adsorption surface area measurements revealed a gradual decrease in the surface area of the silica aerogels with increasing numbers of W ALD cycles, consistent with a partial filling of the aerogel voids. The high density nanoporous tungsten monoliths survived high temperature vacuum heating (1500 Degree-Sign C) making them promising candidates for solid rare-isotope catchers that can be used in the production of short-lived radioactive isotope beams in facilities such as the facility for rare isotope beams (FRIB).

Mane, Anil U.; Greene, John P.; Nolen, Jerry A. [Argonne National Laboratory, 9700 South Cass Avenue, Argonne, IL 60439 (United States); Sampathkumaran, Uma; Owen, Thomas W.; Winter, Ray [InnoSence LLC, 2531 West 237 Street, Torrance, CA 90505 (United States); Elam, Jeffrey W., E-mail: jelam@anl.gov [Argonne National Laboratory, 9700 South Cass Avenue, Argonne, IL 60439 (United States)

2012-06-15

311

Refractory nanoporous materials fabricated using tungsten atomic layer deposition on silica aerogels  

International Nuclear Information System (INIS)

We report an approach for preparing refractory nanoporous materials using high surface area silica aerogels as templates for the growth of conformal tungsten (W) coatings by atomic layer deposition (ALD). Nanoporous silica aerogel monoliths were prepared with a variety of initial pore sizes and initial densities in the range of 0.3-0.5 g/cc using porogen extraction methods. Next, W ALD using Si2H6 and WF6 reactants at 200 °C was employed to coat the inner surfaces of the silica aerogels. After coating, scanning electron microscopy revealed a microstructure in which the ALD W completely encapsulated the silica aerogel micro-cells. The porosity of the aerogels was preserved during the first 10 W ALD cycles allowing the density to be controlled by adjusting the number of W ALD cycles to achieve densities as high as 5 g/cc. Nitrogen adsorption surface area measurements revealed a gradual decrease in the surface area of the silica aerogels with increasing numbers of W ALD cycles, consistent with a partial filling of the aerogel voids. The high density nanoporous tungsten monoliths survived high temperature vacuum heating (1500 °C) making them promising candidates for solid rare-isotope catchers that can be used in the production of short-lived radioactive isotope beams in facilities such as the facility for rare isotope beams (FRIB).

312

Refractory nanoporous materials fabricated using tungsten atomic layer deposition on silica aerogels  

Science.gov (United States)

We report an approach for preparing refractory nanoporous materials using high surface area silica aerogels as templates for the growth of conformal tungsten (W) coatings by atomic layer deposition (ALD). Nanoporous silica aerogel monoliths were prepared with a variety of initial pore sizes and initial densities in the range of 0.3-0.5 g/cc using porogen extraction methods. Next, W ALD using Si2H6 and WF6 reactants at 200 °C was employed to coat the inner surfaces of the silica aerogels. After coating, scanning electron microscopy revealed a microstructure in which the ALD W completely encapsulated the silica aerogel micro-cells. The porosity of the aerogels was preserved during the first 10 W ALD cycles allowing the density to be controlled by adjusting the number of W ALD cycles to achieve densities as high as 5 g/cc. Nitrogen adsorption surface area measurements revealed a gradual decrease in the surface area of the silica aerogels with increasing numbers of W ALD cycles, consistent with a partial filling of the aerogel voids. The high density nanoporous tungsten monoliths survived high temperature vacuum heating (1500 °C) making them promising candidates for solid rare-isotope catchers that can be used in the production of short-lived radioactive isotope beams in facilities such as the facility for rare isotope beams (FRIB).

Mane, Anil U.; Greene, John P.; Nolen, Jerry A.; Sampathkumaran, Uma; Owen, Thomas W.; Winter, Ray; Elam, Jeffrey W.

2012-06-01

313

Elimination of initial stress-induced curvature in a micromachined bi-material composite-layered cantilever  

Science.gov (United States)

Micro-devices with a bi-material-cantilever (BMC) commonly suffer initial curvature due to the mismatch of residual stress. Traditional corrective methods to reduce the residual stress mismatch generally involve the development of different material deposition recipes. In this paper, a new method for reducing residual stress mismatch in a BMC is proposed based on various previously developed deposition recipes. An initial material film is deposited using two or more developed deposition recipes. This first film is designed to introduce a stepped stress gradient, which is then balanced by overlapping a second material film on the first and using appropriate deposition recipes to form a nearly stress-balanced structure. A theoretical model is proposed based on both the moment balance principle and total equal strain at the interface of two adjacent layers. Experimental results and analytical models suggest that the proposed method is effective in producing multi-layer micro cantilevers that display balanced residual stresses. The method provides a generic solution to the problem of mismatched initial stresses which universally exists in micro-electro-mechanical systems (MEMS) devices based on a BMC. Moreover, the method can be incorporated into a MEMS design automation package for efficient design of various multiple material layer devices from MEMS material library and developed deposition recipes.

Liu, Ruiwen; Jiao, Binbin; Kong, Yanmei; Li, Zhigang; Shang, Haiping; Lu, Dike; Gao, Chaoqun; Chen, Dapeng

2013-09-01

314

Preparation and biological evaluation of a fibroblast growth factor-2-apatite composite layer on polymeric material  

Energy Technology Data Exchange (ETDEWEB)

A polymeric percutaneous device with good biocompatibility and resistance to bacterial infection is required clinically. In this study, a fibroblast growth factor-2 (FGF-2)-hydroxyapatite (HAp) composite layer (FHAp layer) was formed on the surfaces of ethylene-vinyl alcohol copolymer (EVOH) specimens using a coating process in a supersaturated calcium phosphate solution supplemented with FGF-2. FGF-2 in the FHAp layer retained its biological activity to promote proliferation of fibroblasts. The EVOH specimens coated with HAp and FHAp layers were percutaneously implanted in the scalp of rats. Not only the HAp layer but also the FHAp layer showed good biocompatibility, and FGF-2 showed no harmful effects on the skin tissue responses to the implanted specimen as long as 14 d. No significantly higher infection resistance was verified for the FHAp layer over the HAp layer, although an FHAp layer coated on a metallic percutaneous device for bone fixation demonstrated higher resistance to bacterial infection over an HAp layer in the previous study. The efficacy of FHAp layers coated on percutaneous implants in resistance to bacterial infection depends on physical factors including fixation condition, stiffness and movement of implants.

Sasaki, Kenkichi; Kamitakahara, Masanobu; Ioku, Koji [Graduate School of Environmental Studies, Tohoku University, Aoba 6-6-20, Aramaki, Aoba-ku, Sendai 980-8579 (Japan); Oyane, Ayako [Nanosystem Research Institute, National Institute of Advanced Industrial Science and Technology (AIST), Central 4, 1-1-1 Higashi, Tsukuba, Ibaraki 305-8562 (Japan); Hyodo, Koji [Human Technology Research Institute, National Institute of Advanced Industrial Science and Technology (AIST), 1-2-1 Namiki, Tsukuba, Ibaraki 305-8564 (Japan); Ito, Atsuo; Sogo, Yu, E-mail: a-oyane@aist.go.j [Human Technology Research Institute, National Institute of Advanced Industrial Science and Technology (AIST), Central 6, 1-1-1, Higashi, Tsukuba, Ibaraki 305-8566 (Japan)

2010-12-15

315

A high-capacity, low-cost layered sodium manganese oxide material as cathode for sodium-ion batteries.  

Science.gov (United States)

A layered sodium manganese oxide material (NaMn3 O5 ) is introduced as a novel cathode materials for sodium-ion batteries. Structural characterizations reveal a typical Birnessite structure with lamellar stacking of the synthetic nanosheets. Electrochemical tests reveal a particularly large discharge capacity of 219 mAh g(-1) in the voltage rang of 1.5-4.7 V vs. Na/Na(+) . With an average potential of 2.75 V versus sodium metal, layered NaMn3 O5 exhibits a high energy density of 602 Wh kg(-1) , and also presents good rate capability. Furthermore, the diffusion coefficient of sodium ions in the layered NaMn3 O5 electrode is investigated by using the galvanostatic intermittent titration technique. The results greatly contribute to the development of room-temperature sodium-ion batteries based on earth-abundant elements. PMID:24919424

Guo, Shaohua; Yu, Haijun; Jian, Zelang; Liu, Pan; Zhu, Yanbei; Guo, Xianwei; Chen, Mingwei; Ishida, Masayoshi; Zhou, Haoshen

2014-08-01

316

On the electric space charge distribution in a near-surface layer of beta-radiometric dielectric materials  

International Nuclear Information System (INIS)

The effect of the diffusion of elastically scattered part of ?-decay electrons on the electric charge distribution in a near-surface layer of radioactive dielectric materials is theoretically considered. It is shown that the diffusion sources account leads to substantial change in the space charge structure

317

An efficient interpolation for calculation of the response of composite layered material and its implementation in MUSIC imaging  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Focus is on computing the response of a layered composite anisotropic material to a source not close to the domain of interest. A novel interpolation and integration method taking care of fast oscillating spectral response is proposed. The implementation into the multiple signal classification (MUSIC) imaging method is presented also.

Rodeghiero, Giacomo; Zhong, Yu; Lambert, Marc; Lesselier, Dominique; Chen, Xudong

2013-01-01

318

A Gaussian Treatment for the Friction Issue of Lennard-Jones Potential in Layered Materials: Application to Friction between Graphene, MoS2 and Black Phosphorus  

Digital Repository Infrastructure Vision for European Research (DRIVER)

The Lennard-Jones potential is widely used to describe the interlayer interactions within layered materials like graphene. However, it is also widely known that this potential strongly underestimates the frictional properties for layered materials. Here we propose to supplement the Lennard-Jones potential by a Gaussian-type potential, which enables more accurate calculations of the frictional properties of two-dimensional layered materials. Furthermore, the Gaussian potentia...

Jiang, Jin-wu; Park, Harold S.

2015-01-01

319

Results of Tests with Large Sacrificial and Self-Cleaning Strainers and the installation at Ringhals 2  

International Nuclear Information System (INIS)

The paper describes briefly activities performed by Vattenfall Utveckling AB at Alvkarleby Laboratory as part of the qualification programme for the new ECCS strainers at PWR plant Ringhals 2 based on the 'robust solution' with large sacrificial strainers and a self-cleaning 'wing-strainer' of same type as used for the five modified Swedish BWR plants. With the new knowledge gained from several BWR strainer projects following the BarseNick strainer incident in 1992, the functioning of ECCS strainers for PWR was re-evaluated. The upgrading at Ringhals 2, a 3-loop Westinghouse plant having fiberglass and mineral wool as insulation, was the result of a design study including a lot of experimental work mainly in 1993 and 1994. The new ECC system was installed in 5 days in the summer outage 1995. In a first study in year 1993 in the large test tank at Alvkarleby Laboratory it was discovered that the earlier design basis for debris settlement was not fulfilled. Recirculating water falling from a large break will not only prevent settling of the fibrous insulation debris but also disintegrate wads and larger pieces to fibres and fines. It could no longer be assumed that the insulation would settle in front of the strainers. This discovery affected the further work within the project group and the work at Alvkarleby Laboratory. It is presented some test data that have not been published before, e.g. combinations of fibres and particulate material. The test programme included ate material. The test programme included also chemical treated fibrous insulation as well as combinations with carbon powder or oil. Also experiences from combinations of fibres and RMI debris were gained. Some information from projects later performed for the US market are included. Also it is included some experience on deviations in results when tests are performed in different ways. At the end the modified strainer system for Ringhals 2 is presented. (author)

320

Design considerations for electrode buffer layer materials in polymer solar cells.  

Science.gov (United States)

Electrode buffer layers in polymer-based photovoltaic devices enable highly efficient devices. In the absence of buffer layers, we show that diode rectification is lost in ITO/P3HT:PCBM/Ag (ITO = indium tin oxide; P3HT = poly(3-hexylthiophene); PCBM = phenyl C61-butyric acid methyl ester) devices due to nonselective charge injection through the percolated phase pathways of a bulk heterojunction active layer. Charge-selective injection, and thus rectification and device function, can be regained by placing thin, polymeric buffer layers that break the direct electrode-active layer contact. Additionally, we show that strong active layer-buffer layer interactions lead to unwanted vertical phase separation and a kinked current-voltage curve. Device function is regained, increasing power conversion efficiency from 3.6% to 7.2%, by placing a noninteracting layer between the buffer and active layer. These results guide the design and selection of future polymeric electrode buffer layers for efficient polymer solar cell devices. PMID:25116039

Bilby, David; Frieberg, Bradley; Kramadhati, Shobhita; Green, Peter; Kim, Jinsang

2014-09-10

 
 
 
 
321

Numerical simulation of phase change material composite wallboard in a multi-layered building envelope  

International Nuclear Information System (INIS)

Highlights: ? A numerical method to study the heat transfer through a PCM composite wallboard is presented. ? PCM wallboard can reduce energy consumption and shift peak electricity load. ? There is an optimal location for the PCM wallboard in the building envelop. ? The PCM wallboard performance depends on weather conditions. - Abstract: Phase change materials (PCMs) have the capability to store/release massive latent heat when undergoing phase change. When impregnated or encapsulated into wallboard or concrete systems, PCMs can greatly enhance their thermal energy storage capacity and effective thermal mass. When used in the building envelope PCM wallboard has the potential to improve building operation by reducing the energy requirement for maintaining thermal comfort, downsizing the AC/heating equipment, and shifting the peak load from the electrical grid. In this work we numerically studied the potential of PCM on energy saving for residential homes. For that purpose we solved the one-dimensional, transient heat equation through the multi-layered building envelope using the Crank–Nicolson discretization scheme. A source term is incorporated to account for the thermal-physical properties of the composite PCM wallboard. Using this code we examined a PCM composite wallboard incorporated into the walls and roof of a typical residential building across various climate zones. The PCM performance was studied under all seasonal conditions using the latest typical meteorological year (TMY3) data for exterior boundary conditions. Our simulations show that PCM performance highly depends on the weather conditions, emphasizing the necessity to choose different PCMs at different climate zones. Comparisons were also made between different PCM wallboard locations. Our work shows that there exists an optimal location for PCM placement within building envelope dependent upon the resistance values between the PCM layer and the exterior boundary conditions. We further identified the energy savings potential by comparing the performance of the PCM wallboard against the performance of a building envelope without PCM. Our study shows that PCM composite wallboard can reduce the energy consumption in summer and winter and can shift the peak electricity load in the summer

322

Fabrication of nano-sized metal patterns on flexible polyethylene-terephthalate substrate using bi-layer nanoimprint lithography  

International Nuclear Information System (INIS)

Polymer films are widely used as a substrate for displays and for solar cells since they are cheap, transparent and flexible, and their material properties are easy to design. Polyethylene-terephthalate (PET) is especially useful for various applications requiring transparency, flexibility and good thermal and chemical resistance. In this study, nano-sized metal patterns were fabricated on flexible PET film by using nanoimprint lithography (NIL). Water-soluble poly-vinyl alcohol (PVA) resin was used as a planarization and sacrificial layer for the lift-off process, as it does not damage the PET films and can easily be etched off by using oxygen plasma. NIL was used to fabricate the nano-sized patterns on the non-planar or flexible substrate. Finally, a nano-sized metal pattern was successfully formed by depositing the metal layer over the imprinted resist patterns and applying the lift-off process, which is economic and environmentally friendly, to the PET films.

323

Numerical Investigation of Physicochemical Processes Occurring During Water Evaporation in the Surface Layer Pores of a Forest Combustible Material  

Science.gov (United States)

A numerical investigation of the physicochemical processes occurring during water evaporation from the pores of the surface layer of a forest combustible material has been carried out. The characteristic features of the suppression of the thermal decomposition reaction of a combustible material with water filling fullyits pores and formation of a water fi lm over its surface have been determined. The characteristic times of suppression of thermal decomposition reactions under various environmental conditions and the thickness and kinds of forest combustible material (birch leaves, pine and spruce needles, etc.) have been established.

Zhdanova, A. O.; Kuznetsov, G. V.; Strizhak, P. A.

2014-07-01

324

Analysis of layered scattering materials by pulsed photothermal radiometry: application to photon propagation in tissue.  

Science.gov (United States)

A model of pulsed photothermal radiometry (PPTR) based on optical diffusion theory is presented for a turbid, two-layer, semi-infinite medium containing a surface layer whose optical absorption and scattering properties differ from that of the underlying layer. Assuming one-dimensional geometry, we develop expressions for the depth-dependent fluence distributions and radiant-energy-density profiles and for the time dependence of the PPTR signal. Experimental tests of the PPTR model in a series of layered phantoms of varying optical properties are described. The results of these tests are consistent with the model predictions. PMID:21052451

Vitkin, I A; Wilson, B C; Anderson, R R

1995-06-01

325

Fabrication of functionally graded materials between P21 tool steel and Cu by using laser aided layered manufacturing  

Energy Technology Data Exchange (ETDEWEB)

With the development of layered manufacturing, thermally conductive molds or molds embedding conformal cooling channels can be directly fabricated. Although P21 tool steel is widely used as a mold material because of its dimensional stability, it is not efficient for cooling molds owing to its low thermal conductivity. Hence, the use of functionally graded materials (FGMs) between P21 and Cu may circumvent a tradeoff between the strength and the heat transfer rate. As a preliminary study for the layered manufacturing of thermally conductive molds having FGM structures, one dimensional P21 Cu FGMs were fabricated by using laser aided direct metal tooling (DMT), and then, material properties such as the thermal conductivity and specific heat that are related to the heat transfer were measured and analyzed.

Jeong, Jong Seol; Shin, Ki Hoon [Seoul Nat' l Univ., Seoul (Korea, Republic of)

2013-01-15

326

Cyclododecane as support material for clean and facile transfer of large-area few-layer graphene  

Energy Technology Data Exchange (ETDEWEB)

The transfer of chemical vapor deposited graphene is a crucial process, which can affect the quality of the transferred films and compromise their application in devices. Finding a robust and intrinsically clean material capable of easing the transfer of graphene without interfering with its properties remains a challenge. We here propose the use of an organic compound, cyclododecane, as a transfer material. This material can be easily spin coated on graphene and assist the transfer, leaving no residues and requiring no further removal processes. The effectiveness of this transfer method for few-layer graphene on a large area was evaluated and confirmed by microscopy, Raman spectroscopy, x-ray photoemission spectroscopy, and four-point probe measurements. Schottky-barrier solar cells with few-layer graphene were fabricated on silicon wafers by using the cyclododecane transfer method and outperformed reference cells made by standard methods.

Capasso, A.; Leoni, E.; Dikonimos, T.; Buonocore, F.; Lisi, N. [ENEA, Materials Technology Unit, Surface Technology Laboratory, Casaccia Research Centre, Via Anguillarese 301, 00060 Rome (Italy); De Francesco, M. [ENEA, Technical Unit for Renewable Energies Sources, Casaccia Research Center, Via Anguillarese 301, 00060 Rome (Italy); Lancellotti, L.; Bobeico, E. [ENEA, Portici Research Centre, P.le E. Fermi 1, 80055 Portici (Italy); Sarto, M. S.; Tamburrano, A.; De Bellis, G. [Research Center on Nanotechnology Applied to Engineering of Sapienza (CNIS), SSNLab, Sapienza University of Rome, P.le Aldo Moro 5, 00185 Rome (Italy)

2014-09-15

327

Cyclododecane as support material for clean and facile transfer of large-area few-layer graphene  

International Nuclear Information System (INIS)

The transfer of chemical vapor deposited graphene is a crucial process, which can affect the quality of the transferred films and compromise their application in devices. Finding a robust and intrinsically clean material capable of easing the transfer of graphene without interfering with its properties remains a challenge. We here propose the use of an organic compound, cyclododecane, as a transfer material. This material can be easily spin coated on graphene and assist the transfer, leaving no residues and requiring no further removal processes. The effectiveness of this transfer method for few-layer graphene on a large area was evaluated and confirmed by microscopy, Raman spectroscopy, x-ray photoemission spectroscopy, and four-point probe measurements. Schottky-barrier solar cells with few-layer graphene were fabricated on silicon wafers by using the cyclododecane transfer method and outperformed reference cells made by standard methods.

328

Tribological Investigations of Hard-Faced Layers and Base Materials of Forging Dies with Different Kinds of Lubricants Applied  

Directory of Open Access Journals (Sweden)

Full Text Available This paper gives a procedure for choosing the right technology for reparative hard facing of damaged forging dies. Since they are subject to impact loads and cyclic temperature elevations, forging dies should be made of steel that is able to withstand great impact loads, maintain good mechanical properties at elevated temperatures and that is resistant to wear and thermal fatigue. For these reasons, forging dies are made of conditionally weldable alloy tool steels; however it makes hard facing of damaged tools even more difficult. In this paper, wear resistance of base materials, hard-faced layers and heat-affected zones are tribologically investigated when two different lubricants - pure synthetical oil LM 76 and LM 76 with 6% molybdenum disulfide (MoS2 are applied. Tribological investigations have shown that the wear resistance of the hard faced layers is considerably greater than the wear resistance of the base material. However, the base material has better properties concerning friction.

V. Lazi?

2010-12-01

329

Cyclododecane as support material for clean and facile transfer of large-area few-layer graphene  

Science.gov (United States)

The transfer of chemical vapor deposited graphene is a crucial process, which can affect the quality of the transferred films and compromise their application in devices. Finding a robust and intrinsically clean material capable of easing the transfer of graphene without interfering with its properties remains a challenge. We here propose the use of an organic compound, cyclododecane, as a transfer material. This material can be easily spin coated on graphene and assist the transfer, leaving no residues and requiring no further removal processes. The effectiveness of this transfer method for few-layer graphene on a large area was evaluated and confirmed by microscopy, Raman spectroscopy, x-ray photoemission spectroscopy, and four-point probe measurements. Schottky-barrier solar cells with few-layer graphene were fabricated on silicon wafers by using the cyclododecane transfer method and outperformed reference cells made by standard methods.

Capasso, A.; De Francesco, M.; Leoni, E.; Dikonimos, T.; Buonocore, F.; Lancellotti, L.; Bobeico, E.; Sarto, M. S.; Tamburrano, A.; De Bellis, G.; Lisi, N.

2014-09-01

330

Impact of seed layer on material quality of epitaxial germanium on silicon deposited by low pressure chemical vapor deposition  

International Nuclear Information System (INIS)

The impact of the growth conditions of the germanium seed layer on the material quality of epitaxial germanium grown on (100) silicon by Low Pressure Chemical Vapor Deposition is studied. In order to obtain a smooth surface morphology, a thin Ge seed layer is grown at low temperature, followed by a thick Ge cap layer at high temperature. An optimal seed deposition condition of 335 deg. C and 4 kPa is identified. Seed layer growth at lower temperatures (e.g. 320 deg. C) leads to the formation of crystallographic defects, while growth above 350 deg. C produces unacceptable surface roughening associated with rapid Ge surface diffusion. Seed growth pressures above 6 kPa are found to lead to gas phase nucleation. A qualitative growth model for the Ge seed layer at 335 deg. C and 4 kPa is also described. It is demonstrated that a Ge seed layer thickness greater than 30 nm is required to obtain smooth Ge films. For seed layers at or below 30 nm thicknesses, the lowered thermal stability of this thin film produces severe islanding during the transition to the cap growth temperature (650 deg. C). In situ doping with boron above ?1019 cm-3 in the seed layer enhances the seed growth rate and lowers the Ge/Si interfacial oxygen level. For in situ annealed 2 ?m-thick Ge films deposited on this seed layer, a threading dislocation density of ?2 x 107 cm-2 is achieved, along with a surface roughness of ?1.6 nm of ?1.6 nm

331

Novel hetero-layered materials with tunable direct band gaps by sandwiching different metal disulfides and diselenides.  

Science.gov (United States)

Although bulk hexagonal phases of layered semiconducting transition metal dichalcogenides (STMD) such as MoS2, WS2, WSe2 and MoSe2 exhibit indirect band gaps, a mono-layer of STMD possesses a direct band gap which could be used in the construction of novel optoelectronic devices, catalysts, sensors and valleytronic components. Unfortunately, the direct band gap only occurs for mono-layered STMD. We have found, using first principles calculations, that by alternating individual layers of different STMD (MoS2, WS2, WSe2 and MoSe2) with particular stackings, it is possible to generate direct band gap bi-layers ranging from 0.79 eV to 1.157?eV. Interestingly, in this direct band gap, electrons and holes are physically separated and localized in different layers. We foresee that the alternation of different STMD would result in the fabrication of materials with unprecedented optical and physico-chemical properties that would need further experimental and theoretical investigations. PMID:23528957

Terrones, Humberto; López-Urías, Florentino; Terrones, Mauricio

2013-01-01

332

Effect of Soft Material Hardness and Hard Material Surface Morphology on Friction and Transfer Layer Formation; Dry Condition  

Directory of Open Access Journals (Sweden)

Full Text Available The morphological features of the surface in both micro and macro levels are important factors governing the tribological behavior of the contacting surfaces. Surface hardness is also an important factor which governs the friction and wear behaviors of the contacting surfaces. Surface morphology of a tool is an important factor as it primarily controls the tribological behavior at the interface which in turn controls the surface finish of products. In the present investigation a pin-on-plate sliding tester was used to identify the effect of surface morphology and hardness on co-efficient of friction and transfer layer which characterizes the tribological behavior. The morphology of mild steel (EN8 plate surfaces were modified by employing three different surface modification methods like grinding (silicon carbide wheel polishing, shot blasting and electric discharge machining methods. Surface roughness parameters which characterize the morphology of the steel plates were measured using a three dimensional optical profilometer. Role of hardness is studied by employing lead, copper and Aluminum (Al6082 pins which were slid against steel plates. Experiments were conducted for plate inclination angles of 1, 1.5,2 and 2.5 degrees. Normal load was varied from 1 to 150N during the tests. Experiments were conducted under dry condition in ambient environment. Scanning electron microscope was used to study the formation of transfer layer on plate and pin surfaces. It was observed that the co-efficient of friction and transfer layer formation were found to depend on the surface morphology of the harder surface. The quantum of transfer layer formation on the surfaces is found to increase with increase in surface roughness

Mr.M Basavaraju

2013-09-01

333

Effect of Soft Material Hardness and Hard Material Surface Morphology on Friction and Transfer Layer Formation; Lubricated Condition  

Directory of Open Access Journals (Sweden)

Full Text Available Hot and cold forming of metals is carried out in industry for manufacturing engineering components. Such manufacturing processes employ dies, whose surface condition is one of the factors which characterize the surface finish of engineering components. The surface finish of engineering components is largely influenced by the tribological phenomenon at die and components interface. Lubrication, morphology and hardness of die surface are found to control surface finish of the products. In the present investigation a pin-on-plate sliding tester was used to identify the effect of surface morphology, lubrication and hardness on co-efficient of friction and transfer layer which characterizes the tribological behaviour. The morphology of mild steel (EN8 plate surfaces were modified by employing three different surface modification methods like grinding (silicon carbide wheel polishing, shot blasting and electric discharge machining methods. Surface roughness parameters which characterize the morphology of the steel plates were measured using a three dimensional optical profilometer. Role of hardness is studied by employing lead, copper and Aluminum (Al6082 pins which were slid against steel plates. Experiments were conducted for plate inclination angles of 1, 1.5,2 and 2.5 degrees. Normal load was varied from 1 to 150N during the tests. Experiments were conducted under lubricated condition in ambient environment. Scanning electron microscope was used to study the formation of transfer layer on plate and pin surfaces. It was observed that the co-efficient of friction and transfer layer formation were found to depend on the surface morphology of the harder surface under lubricated condition. The quantum of transfer layer formation on the surfaces is found to increase with increase in surface roughness.

Dr.S Ranganatha

2013-09-01

334

Ciprofloxacin-intercalated Zinc Layered Hydroxides Hybrid Material: Synthesis and in Vitro Release Profiles of an Antibiotic Compound  

International Nuclear Information System (INIS)

The intriguing anion exchange properties of layered hydroxides salts, combined with its high layer charge density have provided strong motivations for the potential use of the inorganic layered host material in drug delivery applications. Ciprofloxacin (CFX), a wide spectrum antibiotic has been anion exchanged with nitrate of zinc hydroxide nitrate (ZHN), which belongs to the LHS family, resulted in the expansion of the basal spacing from 9.92 Amstrom of ZHN to 21.5 Angstrom of ZCFX, the obtained hybrid material. Other characterizations, such as Fourier transform infra red spectroscopy (FTIR), CHNS analysis and TGA/ DTG have further corroborated this finding. Electron microscopy study reveals the plate-like structure of the nano hybrid material. The in vitro release of CFX was performed in phosphate saline buffer at pH 7.4 and it behaves in a slow and sustained release profile over a period of 72 hours. This study suggests that ZHN, which demonstrates a controlled release behavior, could be a potential host material in the drug delivery applications. (author)

335

Submicrometer-sized hierarchical hollow spheres of heavy lanthanide orthovanadates: sacrificial template synthesis, formation mechanism, and luminescent properties.  

Science.gov (United States)

Hollow spheres of heavy lanthanide orthovanadates (LnVO4, Ln = Tb, Dy, Er, Tm, Yb, Lu) and yolk-shell structures of Ho(OH)CO3@HoVO4 have been successfully prepared by employing Ln(OH)CO3 colloidal spheres as a sacrificial template and NH4VO3 as a vanadium source. In particular, the as-obtained LuVO4 hollow spheres are assembled from numerous hollow-structured elliptic nanoparticles, and their textural parameters such as the inner and outer diameters, shell thicknesses, and number of shells could be finely tuned through introducing different amounts of NH4VO3 and employing Lu(OH)CO3 templates with different sizes. The possible mechanisms for the formation of hollow spheres and yolk-shell structures, and also the hollow-structured elliptic nanoparticles of LuVO4, i.e., building blocks of LuVO4 hollow spheres, are proposed and discussed in detail. Under ultraviolet excitation, the obtained LuVO4:Eu(3+) hollow spheres show strong red emissions located in the saturated color region, and the modulation of emission intensity and color purity could be realized by tuning the textural parameters of the obtained hollow spheres. It was found that the nanostructure of the building blocks of LuVO4:Eu(3+) hollow spheres also had an effect on the luminescent properties of the as-obtained materials. Moreover, the quantum efficiency could be affected by the textural parameters of the as-obtained LuVO4:Eu(3+) hollow spheres, and the double-shelled LuVO4:Eu(3+) hollow sphere has the highest quantum efficiency. In addition, the excellent biocompatibility indicates the potential biological applications of LuVO4 hollow spheres. PMID:24308367

Yang, Xiaoyan; Xu, Lin; Zhai, Zheng; Cheng, Fangfang; Yan, Zhenzhen; Feng, Xiaomiao; Zhu, Junjie; Hou, Wenhua

2013-12-23

336

Transient thermal stress analysis of multi-layered composite laminate cylinder and its analytical extension to non-homogeneous materials  

International Nuclear Information System (INIS)

Many kinds of composite materials, which consist of composite structure of matrix material and mixture for reinforcement, have been developed recently. And evaluation or research of their mechanical behaviors have been carried out widely (Vinson et al., 1986). As one of composite materials, metal matrix composites have been developed as new materials which may be adaptable for the super high-temperature environment, and it would be predicted that they show the complicated and characteristic mechanical behaviors, these phenomena could not be shown in isothermal problems due to the external loading. In the present paper, the authors analyze the transient plane thermal stress problem of a multi-layered composite laminated cylinder due to symmetrical and asymmetrical heating. So far as analytical developments for the multi-layered composite cylinder, the authors have introduced the method of Laplace transform to the temperature field and Airy's stress function method to the thermoelastic field, and then evaluated the temperature and thermal stress distributions in a transient state. Moreover, the authors have applied the theoretical developments proposed in this paper into the analysis of a cylinder with nonhomogeneous material properties such as a functionally gradient material

337

Non-local effects in effective medium response of nano-layered meta-materials  

CERN Document Server

We analyze electromagnetic modes in multi-layered nano-composites and demonstrate that the response of a majority of practical layered structures is strongly affected by the effective non-localities, and is not described by conventional effective-medium theories. We develop the analytical description of the relevant phenomena and confirm our results with numerical solutions of Maxwell equations. Finally, we use the developed formalism to demonstrate that multi-layered plasmonic nanostructures support high-index volume modes, confined to deep subwavelength areas.

Elser, J; Salakhutdinov, I; Avrutsky, I; Elser, Justin; Podolskiy, Viktor A.; Salakhutdinov, Ildar; Avrutsky, Ivan

2006-01-01

338

A replacement of high-k process for CMOS transistor by atomic layer deposition  

Science.gov (United States)

A replacement of high-k process was implemented on an independent double gate FinFET, following the ordinary gate-first process with minor modifications. The present scheme involves neither exotic materials nor unprecedented processing. After the source/drain process, the sacrificial gate oxide was selectively substituted with amorphous Ta2O5 via conformal plasma enhanced atomic layer deposition. The present gate-first gate-dielectric-last scheme combines the advantages of the process and design simplicity of the gate-first approach and the control of the effective gate workfunction and the interfacial oxide of the gate-dielectric-last approach. Electrical characterization data and cross-sectional images are provided as evidence of the concept.

Han, Jin-Woo; Choi, Byung Joon; Yang, J. Joshua; Moon, Dong-Il; Choi, Yang-Kyu; Williams, R. Stanley; Meyyappan, M.

2013-08-01

339

A replacement of high-k process for CMOS transistor by atomic layer deposition  

International Nuclear Information System (INIS)

A replacement of high-k process was implemented on an independent double gate FinFET, following the ordinary gate-first process with minor modifications. The present scheme involves neither exotic materials nor unprecedented processing. After the source/drain process, the sacrificial gate oxide was selectively substituted with amorphous Ta2O5 via conformal plasma enhanced atomic layer deposition. The present gate-first gate-dielectric-last scheme combines the advantages of the process and design simplicity of the gate-first approach and the control of the effective gate workfunction and the interfacial oxide of the gate-dielectric-last approach. Electrical characterization data and cross-sectional images are provided as evidence of the concept. (fast track communication)

340

Structure and magnetism of new hybrid cobalt hydroxide materials built from decorated brucite layers  

Digital Repository Infrastructure Vision for European Research (DRIVER)

The structure, synthesis and magnetic properties of three new complex cobalt hydroxyl oxalates are presented, showing a modification of the 2-D double layer hydroxide structure. Co12(OH)18(ox)3(pip) [ox = oxalate, C2O42?; pip = piperazine, C4N2H10] (1), is essentially built from brucite-like layers with a one ninth depletion of the octahedral sites and a preservation of a trigonal crystallogra...

Keene, T. D.; Light, M. E.; Hursthouse, M. B.; Price, D. J.

2011-01-01

 
 
 
 
341

Flaw investigation in a multi-layered, multi-material composite: Using air-coupled ultrasonic resonance imaging  

Science.gov (United States)

Ceramic tiles are the main ingredient of a multi-material, multi-layered composite being considered for the modernization of tank armors. The high stiffness, low attenuation, and precise dimensions of these uniform tiles make them remarkable resonators when driven to vibrate. Defects in the tile, during manufacture or after usage, are expected to change the resonance frequencies and resonance images of the tile. The comparison of the resonance frequencies and resonance images of a pristine tile/lay-up to a defective tile/lay-up will thus be a quantitative damage metric. By examining the vibrational behavior of these tiles and the composite lay-up with Finite Element Modeling and analytical plate vibration equations, the development of a new Nondestructive Evaluation technique is possible. This study examines the development of the Air-Coupled Ultrasonic Resonance Imaging technique as applied to a hexagonal ceramic tile and a multi-material, multi-layered composite.

Livings, R. A.; Dayal, V.; Barnard, D. J.; Hsu, D. K.

2012-05-01

342

Cathodic protection by zinc sacrificial anodes: impact on marine sediment metallic contamination.  

Science.gov (United States)

Cathodic protection by sacrificial zinc anodes is often applied to prevent immerged metallic structures from corrosion. But this technique induces the zinc anodes dissolution, which can induce marine sediments and seawater contamination. A large scale experiment, in natural seawater, was conducted during 12 months, in order to evaluate the potential environmental impact of this continuous zinc dissolution, and of some necessary cleaning operations of the anodes surfaces. The heavy metal (Cr, Cu, Pb and Zn) concentration in water and sediment samples was monitored. A sequential extraction procedure was applied on sediment samples to differentiate the zinc mobile fractions from the residual one. A significant increase of zinc concentration was observed in water as well as in the surface sediments under the specific operating conditions. Sediments then become a secondary pollution source, as the sorbed labile zinc can be remobilized to seawater. PMID:19250740

Rousseau, C; Baraud, F; Leleyter, L; Gil, O

2009-08-15

343

Silicon nanotubes from sacrificial silicon nanowires: fabrication and manipulation via embedding in flexible polymers  

International Nuclear Information System (INIS)

In the present work we report a simple method to fabricate Si nanotubes (NTs) starting from the growth of self-assembled sacrificial Si nanowires that, at the same time, embeds them into a polyimide matrix, allowing a very easy manipulation of these nano-objects, including removal, transfer and positioning. Our all-silicon fabrication method is completely compatible with the Si technology platform and is therefore implementable using the existing technology. Transferred NTs show good electrical contact with underlying electrodes, and relatively low resistance values have been measured. All these features demonstrate the effectiveness of the transfer method and the potentiality of the NTs in electronics. Finally, optical reflectivity of the NTs has been measured in the near UV–near IR spectral range. (paper)

344

De un sendero sacrificial surcado de goce // from a sacrificed path plow through of pleasure  

Directory of Open Access Journals (Sweden)

Full Text Available El presente trabajo discierne un semblante maldito del sacrificio. En nombre del amor se ha idealizado el sacrificio como paradigma de su audacia y heroísmo, mientras la cultura se ha encargado de enaltecer la proeza sacrificial como puesta en acto del amor. El destinatario de esta inmolación suprema inscribe la producción del goce divino en calidad de objeto “a”, tal como lo revelan sacrificios paradigmáticos presentes en la historia y la literatura. // The current work discerns a cursed countenance from the sacrifice. The sacrifice has been idealized in love's name, as paradigm of its courage and heroism, meanwhile the culture has taken charge of dignifying the sacrificed feat as event in the love act. The addressee of this supreme immolation registers the production of the divine enjoyment as “a” object, just as it is revealed by paradigmatic sacrifices present on history and literature.

Mario Orozco Guzmán

2011-06-01

345

Aluminum alloy for cladding excellent in sacrificial anode property and erosion-corrosion resistance  

International Nuclear Information System (INIS)

An aluminum alloy for cladding excellent in sacrificial anode property and erosion-corrosion resistance, which consists essentially of, in weight percentage: zinc - 0.3 to 3.0%, magnesium - 0.2 to 4.0%, manganese - 0.3 to 2.0%, and, the balance aluminum and incidental impurities; said alloy including an aluminum alloy also containing at least one element selected from the group consisting of, in weight percentage: indium - 0.005 to 0.2%, tin - 0.01 to 0.3%, and, bismuth - 0.01 to 0.3%; provided that the total content of indium, tin and bismuth being up to 0.3%

346

Magnetic materials. Tilt engineering of spontaneous polarization and magnetization above 300 K in a bulk layered perovskite.  

Science.gov (United States)

Crystalline materials that combine electrical polarization and magnetization could be advantageous in applications such as information storage, but these properties are usually considered to have incompatible chemical bonding and electronic requirements. Recent theoretical work on perovskite materials suggested a route for combining both properties. We used crystal chemistry to engineer specific atomic displacements in a layered perovskite, (Ca(y)Sr(1- y))(1.15)Tb(1.85)Fe2O7, that change its symmetry and simultaneously generate electrical polarization and magnetization above room temperature. The two resulting properties are magnetoelectrically coupled as they arise from the same displacements. PMID:25613888

Pitcher, Michael J; Mandal, Pranab; Dyer, Matthew S; Alaria, Jonathan; Borisov, Pavel; Niu, Hongjun; Claridge, John B; Rosseinsky, Matthew J

2015-01-23

347

Characterization of the Minimum Effective Layer of Thermal Insulation Material Tow-plaster from the Method of Thermal Impedance  

Directory of Open Access Journals (Sweden)

Full Text Available Our objective in this study is to determine the effective thermal insulating layer of a composite towplaster. The characterization of thermal insulating material is proposed from the study of the thermal impedance in dynamic two-dimensional frequency. Thermo physical properties of the material tow-plaster are determined from the study of the thermal impedance. Nyquist representations have introduced an interpretation of certain phenomena of heat transfer from the series and shunt resistors. The overall coefficient of heat exchange is determined from the Bode plots. A method for determining the thermal conductivity is proposed.

M.S. Ould Brahim

2011-04-01

348

Novel layered crystalline organic polymer-inorganic hybrid material comprising calcium phosphate with unique architectures for superior performance catalyst support.  

Science.gov (United States)

An organic copolymer-inorganic hybrid material, calcium phosphonate-phosphate (CaPS-PVPA), is fabricated under mild conditions. In particular, CaPS-PVPA is not prepared with traditional methods such as a hydrothermal one, but with amorphous reactions for a simple, fast, cost-effective and environmentally benign approach. Characterization shows that CaPS-PVPA is a layered crystalline mesoporous material, and could be readily used as a catalytic support. A catalyst with immobilization of chiral salen Mn(iii) onto CaPS-PVPA demonstrate a superior catalytic disposition (conv. > 99% and ee > 99%), which offers great potential for industry scale applications. PMID:25340324

Huang, Jing; Tang, Mei; Li, Xin; Zhong, Guo Zhen; Li, Chang Ming

2014-12-14

349

Co-release of cells and polymeric nanoparticles from sacrificial microfibers enhances nonviral gene delivery inside 3D hydrogels.  

Science.gov (United States)

Hydrogels can promote desirable cellular phenotype by mimicking tissue-like stiffness or serving as a gene delivery depot. However, nonviral gene delivery inside three-dimensional (3D) hydrogels remains a great challenge, and increasing hydrogel stiffness generally results in further decrease in gene delivery efficiency. Here we report a method to enhance nonviral gene delivery efficiency inside 3D hydrogels across a broad range of stiffness using sacrificial microfibers for co-releasing cells and polymeric nanoparticles (NPs). We fabricated hydrolytically degradable alginate as sacrificial microfibers, and optimized the degradation profile of alginate by varying the degree of oxidization. Scanning electron microscopy confirmed degradation of alginate microfibers inside hydrogels, leaving behind microchannel-like structures within 3D hydrogels. Sacrificial microfibers also serve as a delivery vehicle for co-releasing encapsulated cells and NPs, allowing cell attachment and spreading within the microchannel surface upon microfiber degradation. To examine the effects of sacrificial microfibers on nonviral gene delivery inside 3D hydrogels, alginate microfibers containing human embryonic kidney 293 cells and polymeric NPs were encapsulated within 3D hydrogel scaffolds with varying stiffness (9, 58, and 197?kPa). Compared with cells encapsulated in bulk hydrogels, we observed up to 15-fold increase in gene delivery efficiency using sacrificial microfibers, and gene delivery efficiency increased as hydrogel stiffness increased. The platform reported herein provides a strategy for enhancing nonviral gene delivery inside 3D hydrogels across a broad range of stiffness, and may aid tissue regeneration by engaging both mechanotransduction and nonviral gene delivery. PMID:24483329

Madl, Christopher M; Keeney, Michael; Li, Xiaolan; Han, Li-Hsin; Yang, Fan

2014-10-01

350

A WOOD REPLACEMENT MATERIAL OF SANDWICH STRUCTURE USING COIR FIBER MATS AND FIBERGLASS FABRICS AS CORE LAYER  

Directory of Open Access Journals (Sweden)

Full Text Available The tensile strength and bending strength of natural coir fiber are lower than many other natural fibers. Therefore, coir fiber is unsuitable for many fiber reinforcement applications. This study exploits the better shock resistance and toughness of coir fiber, which suggest that coir fiber can be used as a type of replacement material in plywood. Fast-growing poplar was chosen as the surface material, and coir fiber was selected as the core layer material for their buffering ability and toughness, and fiberglass fabrics were added in the core layer as strengthening components. The optimization of this plywood structure was carried out with an orthogonal experiment and the intuitive analysis method. The mechanical performance of some samples even exceeded that of natural wood. Through analysis of test results and scanning electron microscope (SEM observations, the buffering and toughening mechanisms of the coir fiber mats were revealed. This new material can be used to replace wood in plywood and in the transportation industry as a packaging material and as platform floors for freight vehicles.

Jia Yao,

2011-12-01

351

Four-layer tin-carbon nanotube yolk-shell materials for high-performance lithium-ion batteries.  

Science.gov (United States)

All high-capacity anodes for lithium-ion (Li-ion) batteries, such as those based on tin (Sn) and silicon (Si), suffer from large volume changes during cycling with lithium ions, and their high capacities can be only achieved in the first few cycles. We design and synthesize a unique four-layer yolk-shell tin-carbon (Sn-C) nanotube array to address this problem. The shape and size of the exterior Sn?nanotube@carbon core-shell layer, the encapsulated interior Sn nanowire@carbon nanotube core-shell layer, and the filling level of each layer can be all controlled by adjusting the experimental conditions. Such a nanostructure has not been reported for any metal or metal oxide-based material. Owing to the special design of the electrode structure, the four-layer hierarchical structure demonstrates excellent Li-ion storage properties in terms of high capacity, long cycle life, and high rate performance. PMID:24648261

Chen, Peng; Wu, Fengdan; Wang, Yong

2014-05-01

352

Influence of the type of ceramic moulding materials on the top layer of titanium precision castings  

Directory of Open Access Journals (Sweden)

Full Text Available The article presents the results of the research which was executed to describe the conditions specific of the formation of surface of certain micro-geometry and of the upper layers on precision titanium castings for medical industry. On the ready precision castings some tests were carried out to obtain the surface micro-geometry satisfying the requirements of implants to be used in human organism. The surfaces with specific spherical macro-unevenness were formed as well as plane surfaces of 2 ÷ 6 ?m roughness. With the help of the light and electron microscopy, the possibility of formation of upper layers directly through an interaction of liquid titanium or Ti6Al4V alloy with the first layer of ceramic mould made from the ceramic mixtures based on Ekosil binder and molochite or zirconia has been confirmed.

Myszka D.

2007-01-01

353

Stacking and registry effects in layered materials: the case of hexagonal boron nitride.  

Science.gov (United States)

The interlayer sliding energy landscape of hexagonal boron nitride (h-BN) is investigated via a van der Waals corrected density functional theory approach. It is found that the main role of the van der Waals forces is to anchor the layers at a fixed distance, whereas the electrostatic forces dictate the optimal stacking mode and the interlayer sliding energy. A nearly free-sliding path is identified, along which band gap modulations of ?0.6??eV are obtained. We propose a simple geometric model that quantifies the registry matching between the layers and captures the essence of the corrugated h-BN interlayer energy landscape. The simplicity of this phenomenological model opens the way to the modeling of complex layered structures, such as carbon and boron nitride nanotubes. PMID:20867872

Marom, Noa; Bernstein, Jonathan; Garel, Jonathan; Tkatchenko, Alexandre; Joselevich, Ernesto; Kronik, Leeor; Hod, Oded

2010-07-23

354

Heat transfer and material flow during laser assisted multi-layer additive manufacturing  

Energy Technology Data Exchange (ETDEWEB)

A three-dimensional, transient, heat transfer, and fluid flow model is developed for the laser assisted multilayer additive manufacturing process with coaxially fed austenitic stainless steel powder. Heat transfer between the laser beam and the powder particles is considered both during their flight between the nozzle and the growth surface and after they deposit on the surface. The geometry of the build layer obtained from independent experiments is compared with that obtained from the model. The spatial variation of melt geometry, cooling rate, and peak temperatures is examined in various layers. The computed cooling rates and solidification parameters are used to estimate the cell spacings and hardness in various layers of the structure. Good agreement is achieved between the computed geometry, cell spacings, and hardness with the corresponding independent experimental results.

Manvatkar, V.; De, A.; DebRoy, T. [Department of Materials Science and Engineering, The Pennsylvania State University, University Park, Pennsylvania 16802 (United States)

2014-09-28

355

Shape-selective sieving layers on an oxide catalyst surface  

Science.gov (United States)

New porous materials such as zeolites, metal-organic frameworks and mesostructured oxides are of immense practical utility for gas storage, separations and heterogeneous catalysis. Their extended pore structures enable selective uptake of molecules or can modify the product selectivity (regioselectivity or enantioselectivity) of catalyst sites contained within. However, diffusion within pores can be problematic for biomass and fine chemicals, and not all catalyst classes can be readily synthesized with pores of the correct dimensions. Here, we present a novel approach that adds reactant selectivity to existing, non-porous oxide catalysts by first grafting the catalyst particles with single-molecule sacrificial templates, then partially overcoating the catalyst with a second oxide through atomic layer deposition. This technique is used to create sieving layers of Al2O3 (thickness, 0.4-0.7 nm) with ‘nanocavities’ (TiO2 photocatalyst. The additional layers result in selectivity (up to 9:1) towards less hindered reactants in otherwise unselective, competitive photocatalytic oxidations and transfer hydrogenations.

Canlas, Christian P.; Lu, Junling; Ray, Natalie A.; Grosso-Giordano, Nicolas A.; Lee, Sungsik; Elam, Jeffrey W.; Winans, Randall E.; van Duyne, Richard P.; Stair, Peter C.; Notestein, Justin M.

2012-12-01

356

COMPOSITION OSCILLATIONS IN HARD MATERIAL LAYERS DEPOSITED FROM THE VAPOUR PHASE  

Digital Repository Infrastructure Vision for European Research (DRIVER)

For the deposition of hard layers on hard metals from the gas phase in the systems Ti-C-B, Ti-N-B, Ti-V-C-O, Ti-Zr-C, Ti-C-N, Ti-C, B-C and Si-C at selected deposition conditions the existence of oscillations was established, which result in a lamellar structure of the layers. As shown by Auger-Spectroscopic analyses the composition of the lamellas changes alternately. Reasons for the lamellar deposition are discussed and a qualitative macroscopic model is presented.

Bartsch, K.; Leonhardt, A.; Wolf, E.

1991-01-01

357

Protective layer for nuclear fuel container and powdery spray material for its manufacture  

International Nuclear Information System (INIS)

The protective layer consists of at least 40 weight% of at least one intermetallic boron compound, (with a minimal boron content of 5 weight%), minutely dispersed in a matrix consisting essentially of iron, nickel or an alloy of iron and/or nickel and/or chromium. The thickness of the layer corresponds to a boron-10 isotope content of at least 5 mg/cm2/. By this means, a high neutron capture cross section combined with very good long-time corrosion resistance and mechanical properties is achieved

358

Production of Quasicomposite Surface Layer of a Metal Material by Shock Wave Strain Hardening  

Directory of Open Access Journals (Sweden)

Full Text Available Quite often in order to improve the performance of a product it is necessary to form a strengthened structure that will be extremely hard and have good plasticity at the same time. One way to meet this challenge is to apply shock wave mechanical hardening to produce micro- or nanocrystalline heterogeneous structures in homogeneous metals or alloys. A peculiar feature of such structure is its layer-by-layer formation with smooth transition between hard and plastic areas, which improves the performance of the strengthened item significantly

A.V. Kirichek

2014-07-01

359

Novel Growing Integration Layer (GIL) method for joining/bonding of metallic and ceramic materials, and its applications for bulk metallic glasses with high bioactivities  

International Nuclear Information System (INIS)

This article describes a new approach to overcome the cracking and peeling of ceramic layer on bulk metallic materials. Based on previous studies and our results, we have proposed a novel concept and technology: Growing Integration Layer (GIL) or Growing Integration Processing (GIP) for the coating, joining and/or bonding of ceramic layer on metallic materials. As one of its application, titanate layers with nano-mesh morphology, having widely diffused interfaces from the Ti-based bulk metallic glass (BMG) have been fabricated by the hydrothermal-electrochemical reaction in an aqueous solutions at low temperatures below 120 oC. This titanate layer could induce the deposition of bone-like hydroxyapatite after 12 days of immersion in a simulated body fluid (SBF). The GIL method exhibited not only the improvement of adhesion performance of ceramic layers but also the introduction of new functionality such as bioactivity to the metallic bulk materials.

360

Near-field pressure distributions to enhance sound transmission into multi-layer materials  

Digital Repository Infrastructure Vision for European Research (DRIVER)

The large impedance difference between air and most solids prevents significant energy transfer from incident acoustic waves across the air-material interface. Refraction also plays a role in preventing acoustic transmission, as the wave speed difference between air and solid materials results in an increase of the resulting propagation angles, creating near-field pressure distributions in the solid material. By utilizing evanescent pressure distributions, which decay normal to the usual dire...

Jessop, Andrew M.

2013-01-01

 
 
 
 
361

Analytic expressions for atomic layer deposition: Coverage, throughput, and materials utilization in cross-flow, particle coating, and spatial atomic layer deposition  

International Nuclear Information System (INIS)

In this work, the authors present analytic models for atomic layer deposition (ALD) in three common experimental configurations: cross-flow, particle coating, and spatial ALD. These models, based on the plug-flow and well-mixed approximations, allow us to determine the minimum dose times and materials utilization for all three configurations. A comparison between the three models shows that throughput and precursor utilization can each be expressed by universal equations, in which the particularity of the experimental system is contained in a single parameter related to the residence time of the precursor in the reactor. For the case of cross-flow reactors, the authors show how simple analytic expressions for the reactor saturation profiles agree well with experimental results. Consequently, the analytic model can be used to extract information about the ALD surface chemistry (e.g., the reaction probability) by comparing the analytic and experimental saturation profiles, providing a useful tool for characterizing new and existing ALD processes

362

N-trimethylchitosan/Alginate Layer-by-Layer Self Assembly Coatings Act as "Fungal Repellents" to Prevent Biofilm Formation on Healthcare Materials.  

Science.gov (United States)

Fungal biofilm formation on healthcare materials is a significant clinical concern, often leading to medical-device-related infections, which are difficult to treat. A novel fungal repellent strategy is developed to control fungal biofilm formation. Methylacrylic acid (MAA) is grated onto poly methyl methacrylate (PMMA)-based biomaterials via plasma-initiated grafting polymerization. A cationic polymer, trimethylchitosan (TMC), is synthesized by reacting chitosan with methyl iodide. Sodium alginate (SA) is used as an anionic polymer. TMC/SA multilayers are coated onto the MAA-grafted PMMA via layer-by-layer self-assembly. The TMC/SA multilayer coatings significantly reduce fungal initial adhesion, and effectively prevent fungal biofilm formation. It is concluded that the anti-adhesive property of the surface is due to its hydrophilicity, and that the biofilm-inhibiting action is attributed to the antifungal activity of TMC as well as the chelating function of TMC and SA, which may have acted as fungal repellents. Phosphate buffered saline (PBS)-immersion tests show that the biofilm-modulating effect of the multilayer coatings is stable for more than 4 weeks. Furthermore, the presence of TMC/SA multilayer coatings improves the biocompatibility of the original PMMA, offering a simple, yet effective, strategy for controlling fungal biofilm formation. PMID:25295485

Jiang, Fuguang; Yeh, Chih-Ko; Wen, Jianchuan; Sun, Yuyu

2014-10-01

363

Trapping and depth profile of tritium in surface layers of metallic materials  

Science.gov (United States)

Tritium amount retained in surface layers and release behavior from surface layers were examined using SS316L samples exposed to plasmas in the Large Helical Device and a commercial Cu-Be alloy plate. BIXS analyses and observation by SEM indicate that carbon and titanium deposited on the plasma-facing surface of the SS316L samples. Larger amount of tritium was trapped in the plasma-facing surface in comparison with the polished surface. Higher enrichment of tritium in surface layers was similarly found in the polished surface of both samples. The amount of surface tritium in both samples was almost same, while the bulk concentration of tritium in Cu-Be was much lower than that in SS316L. Tritium release from the SS316L and Cu-Be samples into water was examined by immersion experiments. Tritium elution was observed for both samples, but changes in the residual tritium amount in surface layers were different from each other.

Matsuyama, M.; Chen, Z.; Nisimura, K.; Akamaru, S.; Torikai, Y.; Hatano, Y.; Ashikawa, N.; Oya, Y.; Okuno, K.; Hino, T.

2011-10-01

364

Laser study of phase changes in the surface layer of porous materials  

International Nuclear Information System (INIS)

The paper presents some aspects of the use of interference patterns observed upon reflection of laser radiation from the surface of a porous solid (laser speckles) for the study of moisture condensation in the near-surface layer. (interaction of laser radiation with matter. laser plasma)

365

An ultra-wideband wire spiral antenna for in-body communications using different material matching layers.  

Science.gov (United States)

In this work an ultra-wideband wire antenna was designed and fabricated for transmitting/receiving signals to/from inside the human body. The antenna provides high gain and thus high field intensity in its broadside direction; hence, a high energy density wireless can be established with the inner body. The proposed antenna operates in the frequency band of 3-10 GHz with an impedance of 200 Ohms in free space. The antenna was embedded in different materials with permittivity values ranging from 12 to 74 in order to evaluate the matching layer effect on wave propagation from outside to inside the body. The antenna port impedance was adjusted by using matching circuits. The electric field intensity inside the human chest was calculated for different materials and depths. The best improvement in wave penetration was obtained for the frequency band of 750-1000 MHz by embedding the antenna inside a material with permittivity equal to 27. PMID:25571603

Khaleghi, Ali; Balasingham, Ilangko; Chavez-Santiago, Raul

2014-08-01

366

Fabrication of tubed functionally graded material by slurry dipping process. Thickness control of dip-coated layer  

International Nuclear Information System (INIS)

In order to obtain long life fuel cladding tubes for the fast breeder reactor, the concept of functionally graded material was applied for the material combination of Molybdenum/stainless steel/Titanium, in which Titanium and Molybdenum were placed at the inner and outer sides, respectively. Slurry dipping method was employed because of its capability of shape forming and microstructural control. We have hitherto reported the design criteria for the graded layers, preparation of the slurry, and microstructural control of the dip-coated layers. In the present report, the thickness control of the dip-coated layer is described in detail. The thickness of the dip-coated layer depends primarily on the viscosity of the slurry. Nevertheless, for the stable dispersion of the powder in the slurry, which dominates the microstructural homogeneity, an optimum viscosity value is present for the individual slurries. With stable slurries of Ti, Mo, stainless steel powders and their mixtures, the thicknesses of dip-coated layers were controlled in dependence of their viscosities and yield values. For Ti and stainless steel powders and their mixture a PAANa was used as a dispersing agent. A NaHMP was found to be effective for the dispersion of Mo powder and Mo/stainless steel powder mixture. For all slurries tested in the present investigation PVA addition was helpful for the viscosity control. Dip-coating maps have been drawn for the stabilization of the slurries and for the formation of films with a sufficient strength for further manipulation for the slurries with low viscosity (?10 mPa s). The final film thickness for the low-viscosity slurry with the optimum condition was about 200 ?m. The slurries with high viscosities of several hundreds mPa s had a good stability and the yield value was easy to be controlled. The film thickness was able to be adjusted in the size range between several tens and several hundreds ?m. The final thickness of the graded layer was determined on the basis of the material balance involved and densification ratio attained by drying, sintering and HIP treatment processes. (author)

367

New hybrid material based on layered double hydroxides and biogenic silver nanoparticles: antimicrobial activity and cytotoxic effect  

Scientific Electronic Library Online (English)

Full Text Available SciELO Brazil | Language: English Abstract in portuguese Hidróxidos duplos lamelares (HDLs) têm sido amplamente investigados devido às suas diversas aplicações nas indústrias de materiais e biotecnologia. A combinação de nanopartículas de prata com o material biocompatível HDL pode criar um novo material híbrido com novas propriedades sinergísticas. Neste [...] trabalho, nanopartículas de prata biogênicas (AgNPbio) foram associadas com Mg-Al HDL para obter o material híbrido HDL-AgNPbio. O novo material híbrido obtido foi caracterizado por difratometria de raios X (XRD), microscopias eletrônica de transmissão (TEM) e de varredura com espectroscopia de energia dispersiva por raios-X (MEV-EDS), espectrometria de emissão atômica por plasma acoplado indutivamente (ICP-OES) e espectroscopia na região do infravermelho com transformada de Fourier (FTIR). O HDL foi eficiente em adsorver nanopartículas de prata devido à carga superficial oposta entre as AgNPbio (? = -13,2 mV) e o HDL (? = +3,2 mV). Além disso, as AgNPbio não foram lixiviadas do material híbrido, mesmo após cinco ciclos de lavagem, indicando uma forte interação. Uma importante propriedade deste material híbrido foi a sua atividade antimicrobiana contra Staphylococcus aureus e Escherichia coli e ausência de efeito citotóxico em células de fibroblastos (V79). Este material híbrido é um interessante e promissor nanobiocompósito para aplicações biomédicas e cosméticas. Abstract in english Layered double hydroxides (LDHs) have been widely investigated due to their several applications in the material and biotechnology industries. The combination of silver nanoparticles with biocompatible LDH material can create a new hybrid material with new properties. In this work, biogenic silver n [...] anoparticles (AgNPbio) were associated with Mg-Al LDH to obtain the hybrid material LDH-AgNPbio. The new hybrid material obtained was characterized by X-ray diffractometry (XRD), scanning electron microscopy with energy-dispersive X-ray spectroscopy (SEM-EDS), transmission electron microscopy (TEM), inductively coupled plasma optical emission spectrometry (ICP-OES) and Fourier transform infrared spectroscopy (FTIR). LDH was efficient to absorb silver nanoparticles due to an opposite surface charge between AgNPbio (? = -13.2 mV) and LDH (? = +3.2 mV). Furthermore, AgNPbio was not lixiviated from LDH-AgNPbio, even after five washes, indicating a strong interaction. An important property of this hybrid material was its antimicrobial activity against Staphylococcus aureus and Escherichia coli and absence of cytotoxic effect to fibroblast cell (V79). This hybrid material is an interesting and promising nanobiocomposite for biomedical and cosmetic applications.

Priscyla D., Marcato; Natália V., Parizotto; Diego Stéfani T., Martinez; Amauri J., Paula; Iasmin R., Ferreira; Patrícia S., Melo; Nelson, Durán; Oswaldo L., Alves.

2013-02-01

368

Effect of ?-irradiation on commercial polypropylene based mono and multi-layered retortable food packaging materials  

International Nuclear Information System (INIS)

Irradiation processing of food in the prepackaged form may affect chemical and physical properties of the plastic packaging materials. The effect of ?-irradiation doses (2.5-10.0 kGy) on polypropylene (PP)-based retortable food packaging materials, were investigated using Fourier transform infrared (FTIR) spectroscopic analysis, which revealed the changes happening to these materials after irradiation. The mechanical properties decreased with irradiation while oxygen transmission rate (OTR) was not affected significantly. Colour measurement indicated that Nylon 6 containing multilayer films became yellowish after irradiation. Thermal characterization revealed the changes in percentage crystallinity

369

Cadmium Free Buffer Layers and the Influence of their Material Properties on the Performance of Cu(In,Ga)Se2 Solar Cells  

Digital Repository Infrastructure Vision for European Research (DRIVER)

CdS is conventionally used as a buffer layer in Cu(In,Ga)Se2, CIGS, solar cells. The aim of this thesis is to substitute CdS with cadmium-free, more transparent and environmentally benign alternative buffer layers and to analyze how the material properties of alternative layers affect the solar cell performance. The alternative buffer layers have been deposited using Atomic Layer Deposition, ALD. A theoretical explanation for the success of CdS is that its conduction band, Ec, forms a small p...

Hultqvist, Adam

2010-01-01

370

Atomic layer deposition-based functionalization of materials for medical and environmental health applications  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Nanoporous alumina membranes exhibit high pore densities, well-controlled and uniform pore sizes, as well as straight pores. Owing to these unusual properties, nanoporous alumina membranes are currently being considered for use in implantable sensor membranes and water purification membranes. Atomic layer deposition is a thin-film growth process that may be used to modify the pore size in a nanoporous alumina membrane while retaining a narrow pore distribution. In addition, films deposited by...

Narayan, Roger J.; Adiga, Shashishekar P.; Pellin, Michael J.; Curtiss, Larry A.; Hryn, Alexander J.; Stafslien, Shane; Chisholm, Bret; Shih, Chun-che; Shih, Chun-ming; Lin, Shing-jong; Su, Yea-yang; Jin, Chunming; Zhang, Junping; Monteiro-riviere, Nancy A.; Elam, Jeffrey W.

2010-01-01

371

Mass exchange in adjacent layers of grain material stored in silo  

Directory of Open Access Journals (Sweden)

Full Text Available The paper presents the results of a study on the process of moisture diffusion during barley grain storage in a grain storage silo. The moisture migration was caused by concentration gradient. The study was conducted using a model test station and consisted in the measurement of barley grain moisture and temperature in a silo, and in measuring the pressure exerted by the grain bulk on the silo wall. Analysis of the results showed that none of the parameters studied was stable. It was found that when the grain moisture content applied was 16% in the bottom layer and 10% in the upper layer the average value of grain moisture content in the silo increased from 13.2% to 14.1% over the ten days of the process, while with reverse positioning of the layers in the silo the corresponding increase reached 13.8%. This was due to additional precipitation of water in the course of the process of grain respiration. Moisture diffusion caused an increase in the temperature of the grain within the silo (up to 33°C at ambient temperature of 16°C. Another important effect of the moisture diffusion was the swelling of grains, which caused an increase in the pressure of the barley grain bulk against the silo wall. The highest increase in the wall load was observed at the boundary line between layers of grain of different moisture content levels. The changes in the values of the parameters under study were described by means of regression equations.

Bilański W.K.

1998-06-01

372

Wafer-edge defect reduction for tri-layer materials in BEOL applications  

Science.gov (United States)

As the semiconductor feature size continues to shrink, the thickness of photo resist needs to be thinner and thinner to prevent resist features from collapse. Coupling with the need of high NA lithography for small feature patterning, both the reflectance control and the etch budget on resist thickness are becoming major challenges for lithographers. One way to simultaneously satisfy the needs of superior low reflectance, sufficient etch resistance and minimizing the resist feature collapse is adopting tri-layer lithography scheme. The tri-layer scheme has been successfully implemented in our manufacturing flow for FEOL (Front-End-of-Line) application. This work investigated the application of tri-layer scheme to BEOL (Back-End-of-Line) AlCu patterning. One critical problem met in this application is the defect that majorly originates from wafer edge after AlCu patterning. The defects were finally ascribed to the hump formation of Si-rich hard-mask by EBR (Edge Bead Removal) process. The hump of Si-rich hard-mask yields etch masking behavior during AlCu etch accordingly leads to pattern bridging or peeling of inorganic hard-mask after AlCu patterning. To reduce the defect, several evaluations were made to suppress the hump formation, including the EBR optimization, bake condition of Si-rich hard-mask, film stacking architecture of tri-layer by EBR rinse and surfactant additive added Si-rich hard-mask. A synergy effect among process factors has been proposed to effectively fix the defect problem around wafer edge.

Du, J. R.; Huang, C. H.; Yang, Elvis; Yang, T. H.; Chen, K. C.; Lu, Chih-Yuan

2011-03-01

373

Preparation and Characterization of TiO2/CdS Layers as Potential Photoelectrocatalytic Materials  

Directory of Open Access Journals (Sweden)

Full Text Available The TiO2/CdS semiconductor composites were prepared on
indium tin oxide (ITO substrates in di®erent mass proportions via wet-chemical techniques using bi-distilled water, acetyl-acetone, poly-propylene-glycol and Triton X-100 as additives. The composite layers were annealed in normal conditions at the temperature of 450±C, 120 min. with a rate of temperature increasing of 5±C/min. The structural and optical properties of all the TiO2/CdS ayers were characterized by X-ray di®raction, UV-VIS spectroscopy, spectrofluorimetry and FT/IR microscopy. The microstructural properties of the deposited TiO2/CdS layers can be modi¯ed by varying the mass proportions of TiO2:CdS. The good crystallinity level and the high optical adsorption of
the TiO2/CdS layers make them attractive for photoelectrochemical cell applications.

Teofil-Danut Silipas

2011-01-01

374

Effects of lossy, layered filler particles on the bulk permittivity of a composite material  

International Nuclear Information System (INIS)

The ability to control the frequency at which a dielectric material exhibits maximum loss (the relaxation frequency) is of interest in telecommunications and radar absorption. A theoretical investigation of the behaviour of the complex bulk permittivity of a composite material with coated, spheroidal filler particles is presented. In the model, the filler particles are replaced mathematically by electric multipole sources located at their centres (Harfield N 2000 J. Mater. Sci. 35 5809-16). It is shown how factors such as particle shape, orientation with respect to the applied electric field, thickness of coating and permittivity value of the individual phases influences the bulk permittivity of the composite material. For a composite with coated filler particles, one or two relaxation frequencies may be observed. Employing the theory of Pauly and Schwan (Hanai T 1968 Electrical properties of emulsions Emulsion Science ed P Sherman (London: Academic)), particular attention is paid to the way in which the relaxation frequencies are affected by the material parameters

375

Air-coupled ultrasonic investigation of multi-layered composite materials.  

Science.gov (United States)

Air-coupled ultrasonics is fine alternative for the immersion testing technique. Usually a through transmission and a pitch-catch arrangement of ultrasonic transducers are used. The pitch-catch arrangement is very attractive for non-destructive testing and evaluation of materials, because it allows one-side access to the object. However, this technique has several disadvantages. It is sensitive to specularly reflected and edge waves. A spatial resolution depends on a distance between the transducers. A new method for detection and visualisation of inhomogeneities in composite materials using one-side access air-coupled ultrasonic measurement technique is described. Numerical predictions of Lamb wave interaction with a defect in a composite material are carried out and the interaction mechanism is explained. Experimental measurements are carried out with different arrangements of the transducers. The proposed method enables detect delamination and impact type defects in honeycomb materials. PMID:16797664

Kazys, R; Demcenko, A; Zukauskas, E; Mazeika, L

2006-12-22

376

A new layered indium selenium oxychloride material: Synthesis, structure, and characterization of InSeO 3Cl  

Science.gov (United States)

A new layered indium selenium oxychloride material, InSeO 3Cl has been synthesized by a standard solid-state reaction using In 2O 3, InCl 3, and SeO 2 as reagents. Single-crystal X-ray diffraction was used to determine the structure of the reported material. InSeO 3Cl crystallizes in the orthorhombic space group Pbca (No. 61), with a = 7.0580(14) Å, b = 7.0390(14) Å, c = 16.206(3) Å, V = 805.1(3) Å 3, and Z = 8. InSeO 3Cl has a layered structure consisting of distorted InO 4Cl 2 octahedra and SeO 3 polyhedra. The Se 4+ cations are in asymmetric coordination environment attributed to their stereoactive lone pairs. The lone pairs on the Se 4+ cations approximately point in the [101], [-10-1], [10-1], and [-101] direction. A separation of the halophile and the chalcophile moieties is observed from the reported material. Detailed structural analysis with full characterization including infrared spectroscopy, bond valence calculations, thermogravimetric analysis, elemental analysis, and dipole moment calculations are reported.

Lee, Dong Woo; Ok, Kang Min

2010-12-01

377

Influence of fouling on the efficiency of sacrificial anodes in providing cathodic protection in Southeast Asian tropical seawater.  

Science.gov (United States)

Aluminum and zinc based sacrificial anodes are routinely used to provide corrosion protection to metals (typically steel) exposed to seawater, for example in steel pipelines and storage tanks. However, the high fouling rates experienced in South East Asia means that both the anodes and the metals to be protected rapidly become coated with macrofoulers, which could potentially prevent the anodes from being effective. The present study, involving exposure tests of up to 18 months, indicates that both aluminum and zinc sacrificial anodes remain effective even after being completely coated with biofouling. Furthermore, it was easier to remove the biofouling on the cathodically protected samples than on their unprotected counterparts, possibly due to the higher local pH produced by cathodic protection at the metal and seawater interface. PMID:20818571

Blackwood, D J; Lim, C S; Teo, S L M

2010-10-01

378

Immobilizing highly catalytically active noble metal nanoparticles on reduced graphene oxide: a non-noble metal sacrificial approach.  

Science.gov (United States)

In this work, we have developed a non-noble metal sacrificial approach for the first time to successfully immobilize highly dispersed AgPd nanoparticles on reduced graphene oxide (RGO). The Co3(BO3)2 co-precipitated with AgPd nanoparticles and subsequently sacrificed by acid etching effectively prevents the primary AgPd particles from aggregation. The resulted ultrafine AgPd nanoparticles exhibit the highest activity (turnover frequency, 2739 h(-1) at 323 K) among all the heterogeneous catalysts for the dehydrogenation of formic acid to generate hydrogen without CO impurity. The sacrificial approach opens up a new avenue for the development of high-performance metal nanocatalysts. PMID:25543717

Chen, Yao; Zhu, Qi-Long; Tsumori, Nobuko; Xu, Qiang

2015-01-14

379

Localized corrosion of metallic materials and ? radiation effects in passive layers under simulated radwaste repository conditions. Final report  

International Nuclear Information System (INIS)

The task of the project was to simulate the conditions in a radwaste repository and to perform local analyses in order to detect the critical conditions and material susceptibilities leading to localized corrosion of materials. The information thus obtained was to yield more precise data on the long-term stability of materials for the intended purpose, in order to be able to appropriately select or optimize the materials (Ti, TiO.2Pd, Hastelloy C4, fine-grained structural steel). A major aspect to be examined was natural inhomogeneities of the electrode surfaces, as determined by the grain structure of the selected materials. Thus a laterally inhomogeneous composition in the welded zone induces an inhomogeneous current distribution, and hence strong susceptibility to localized corrosion. This effect was to be quantified, and the localized corrosion processes had to be identified by means of novel, electrochemical methods with a resolution power of ?m. The investigations were to be made under conditions as near to practice as possible, for instance by simulating radwaste repository conditions and performing measurements at elevated temperatures (170 C) in an autoclave. Another task was to examine the radiation effects of ? radiation on passive layers, and describe the possible modifications induced by recrystallisation, photocorrosion, or oxide formation. (orig./MM)

380

Theory of the axi-symmetric extrusion process of multi-layer materials with a strong plastic nonhomogeneity  

Digital Repository Infrastructure Vision for European Research (DRIVER)

A novel simplified r hcorctical solution is found lor thc strcss starcs accompanying thc proccss of cxt ri~siono f ma![ i-laycr matcrialsunder rhc conditions af axial symmetry. Thc solution i~ bawd nn ~ h mc n dcl of pcrfcct plastic material satisfying thc Trcsca yicld condition.thc Haar-Karman conditions bcing sntisficd in each layer. Thc laycrs arc chnnctcrizcd by difrercnt yicld limits and stmng plasticnonhomogeneity. In thc ncighhoi~rhoorol f thc interfaces conrinuous variation of rhc yic...

Piwnik, J.; Patejuk, A.

2008-01-01

 
 
 
 
381

Comparative Study of Charge Trapping Type SOI-FinFET Flash Memories with Different Blocking Layer Materials  

Digital Repository Infrastructure Vision for European Research (DRIVER)

The scaled charge trapping (CT) type silicon on insulator (SOI) FinFET flash memories with different blocking layer materials of Al2O3 and SiO2 have successfully been fabricated, and their electrical characteristics including short-channel effect (SCE) immunity, threshold voltage (Vt) variability, and the memory characteristics have been comparatively investigated. It was experimentally found that the better SCE immunity and a larger memory window are obtained by introducing a high-k Al2O3 bl...

Yongxun Liu; Toshihide Nabatame; Takashi Matsukawa; Kazuhiko Endo; Uchi, Shinichi O.; Junichi Tsukada; Hiromi Yamauchi; Yuki Ishikawa; Wataru Mizubayashi; Yukinori Morita; Shinji Migita; Hiroyuki Ota; Toyohiro Chikyow; Meishoku Masahara

2014-01-01

382

The motion of low energy electrons in thin layers of amorphous materials  

International Nuclear Information System (INIS)

Recently there have been experiments which precisely measure the transmitted current of low energy electrons (0 - 15 eV) through thin layers of matter. The authors aim at a theoretical description of such experiments by representing relevant observable quantities in terms of the autocorrelation of the potential which the electron experiences, in scattering through the medium. For example, the current which is detected may be expresses as a cumulant expansion, the various terms representing the action of the medium on the electron. The cumulants may serve as coefficients of a Langevin type equation. An outline and discussion of the approach is given

383

Thermal shock problem of a generalized thermoelastic layered composite material with variable thermal conductivity  

Directory of Open Access Journals (Sweden)

Full Text Available The dynamic treatment of one-dimensional generalized thermoelastic problem of heat conduction is made for a layered thin plate which is exposed to a uniform thermal shock taking into account variable thermal conductivity. The basic equations are transformed by Laplace transform and solved by a direct method. The solution was applied for a plate of sandwich structure, which is thermally shocked, and is traction-free in the outer sides. The inverses of Laplace transforms are obtained numerically. The temperature, the stress, and the displacement distributions are represented graphically.

2006-01-01

384

Minimum model and its theoretical analysis for superconducting materials with BiS$_2$ layers  

Digital Repository Infrastructure Vision for European Research (DRIVER)

We perform first principles band calculation of the newly discovered superconductor LaO$_{1-x}$F$_x$BiS$_2$, and study the lattice structure and the fluorine doping dependence of the gap between the valence and conduction bands. We find that the distance between La and S as well as the fluorine doping significantly affects the band gap. On the other hand, the four orbital model of the BiS$_2$ layer shows that the lattice structure does not affect this portion of the band. St...

Suzuki, Katsuhiro; Usui, Hidetomo; Kuroki, Kazuhiko

2012-01-01

385

Nuclear-physical method of hydrogen analysis in subsurface layers of materials  

International Nuclear Information System (INIS)

Technique of hydrogen content determination based on the recording of the mixture recoil nuclei separating from the sample analyzed as a result of elastic collision with incident ions is considered. Dependence of certain analytical characteristics of the method (resolution to the depth, the thickness of the layer analyzed etc.) on the type and energy of incident ion, the analysis geometry is investigated. Analysis results of niobium and GaAs samples implanted with hydrogen with the energy of 100 keV and dose of 1016 are presented. Carbon ions with the energies 8.9 and 13.5 MeV have been used in the analysis

386

Stacking and Registry Effects in Layered Materials: The Case of Hexagonal Boron Nitride  

Digital Repository Infrastructure Vision for European Research (DRIVER)

The interlayer sliding energy landscape of hexagonal boron nitride (h-BN) is investigated via a van der Waals corrected density functional theory approach. It is found that the main role of the van der Waals forces is to "anchor" the layers at a fixed distance, whereas the electrostatic forces dictate the optimal stacking mode and the interlayer sliding energy. A nearly free-sliding path is identified, along which bandgap modulations of ~0.6 eV are obtained. We propose a sim...

Marom, Noa; Bernstein, Jonathan; Garel, Jonathan; Tkatchenko, Alexandre; Joselevich, Ernesto; Kronik, Leeor; Hod, Oded

2010-01-01

387

A study on the formation of plastic deformation layer in the steam generator tube materials during fretting wear  

Energy Technology Data Exchange (ETDEWEB)

The wear test of steam generator (SG) tube materials against ferritic stainles steels has been performed to evaluate the wear mechanism in water environment. It is difficult to observe the wear particle layers that are frequently formed in air environment. So the wear rate of SG tube materials in water environment depends on the change of mechanical properties between contact surfaces during fretting test. From the result of the subsurface hardness test, Inconel 690 has high hardness value than Inconel 600 as close to surface and this means that energy must be consumed in the contact surface of Inconel 690 to plastically deform the same volume. Main cause of hardness variation is due to the difference of the stacking fault energy with the chromium content. Besides, the deviation of wear coefficient in the Work-rate model was explained by the change of friction coefficient during fretting wear.

Lee, Y. H.; Kim, I. S. [KAIST, Taejon (Korea, Republic of); Park, Y. S. [KEPRI, Taejon (Korea, Republic of)

2001-05-01

388

A study on the formation of plastic deformation layer in the steam generator tube materials during fretting wear  

International Nuclear Information System (INIS)

The wear test of steam generator (SG) tube materials against ferritic stainles steels has been performed to evaluate the wear mechanism in water environment. It is difficult to observe the wear particle layers that are frequently formed in air environment. So the wear rate of SG tube materials in water environment depends on the change of mechanical properties between contact surfaces during fretting test. From the result of the subsurface hardness test, Inconel 690 has high hardness value than Inconel 600 as close to surface and this means that energy must be consumed in the contact surface of Inconel 690 to plastically deform the same volume. Main cause of hardness variation is due to the difference of the stacking fault energy with the chromium content. Besides, the deviation of wear coefficient in the Work-rate model was explained by the change of friction coefficient during fretting wear

389

Mesoscopic effective material parameters for thin layers modeled as single and double grids of interacting loaded wires  

CERN Document Server

As an example of thin composite layers we consider single and double grids of periodically arranged interacting wires loaded with a certain distributed reactive impedance. Currents induced to the wires by a normally incident plane wave are rigorously calculated and the corresponding dipole moment densities are determined. Using this data and the averaged fields we assign mesoscopic material parameters for the proposed grid structures. These parameters depend on the number of grids, and measure the averaged induced polarizations. It is demonstrated that properly loaded double grids possess polarization response that over some frequency range can be described by assigning negative values for the mesoscopic parameters. Discussion is conducted on the physical meaningfulness to assign such material parameters for thin composite slabs. The results predicted by the proposed method for the double-grid structures are compared with the results obtained using the commonly adopted S-parameter retrieval procedure.

Ikonen, Pekka; Gonzalo, Ramon; Simovski, Constantin; Tretyakov, Sergei

2007-01-01

390

A nuclear physical method for determining helium in surface layers of materials  

International Nuclear Information System (INIS)

The method of recoil nuclei, which permits to obtain data on integral content, differential distribution, and in crystal structures - on location in lattice of helium impUrity atoms without sample destruction, has been considered. The method is based on impurity nuclei recording, which are knocked off the sample layer analyzed as a result of elastic cocollisions with accelerated ions. When heavy ions are used the method of recoil nuclei permits to determine helium impurities with the concentration above 5x1012 atom/cm2. The thickness of the layer analyzed can reach 1 ?m at the resolution approximately 40 nm. Determination of helium impurity implanted with the energy up to 200 keV is possible. Results of helium determination in the alloy Ti-Al-V made using a cyclotron with the energy of nitrogen accelerated ions 16 MeV are presented. The bunch current in the chamber constituted 0.05 ?A. To record recoil nuclei a silicon surface-barrier detector with the resolution 40 keV is used. A good separation of peaks corresponding to recoil nuclei of hydrogen and helium adsorbed on the surface sample, which are implanted with the energy 30 keV and dose 5X1017 and 1x1016 atom/cm2, is observed. Residual concentration of helium constitutes 2.45x1016 atom/cm2 for the introduced dose 5x1017 atom/cm2

391

Approximate Electromagnetic Cloaking of a Dielectric Sphere Using Homogeneous Isotropic Multi-Layered Materials  

Digital Repository Infrastructure Vision for European Research (DRIVER)

In cloaking, a body is hidden from detection by surrounding it by a coating consisting of an unusual anisotropic nonhomogeneous material. The permittivity and permeability of such a cloak are determined by the coordinate transformation of compressing a hidden body into a point or a line. The radially-dependent spherical cloaking shell can b...

Zamel, Hany M.; Essam El Diwany; Hadia El Hennawy

2013-01-01

392

Formation of a CdO Layer on CdS/ZnO Nanorod Arrays to Enhance their Photoelectrochemical Performance.  

Science.gov (United States)

The performance and photocatalytic activity of the well-known CdS/ZnO nanorod array system were improved significantly by the layer-by-layer heterojunction structure fabrication of a transparent conductive oxide (TCO) CdO layer on the CdS/ZnO nanorods. Accordingly, a CdO layer with a thickness of approximately 5-10?nm can be formed that surrounds the CdS/ZnO nanorod arrays after annealing at 500?°C under air. At an external potential of 0.0?V vs. Ag/AgCl, the CdO/CdS/ZnO nanorod array electrodes exhibit an increased incident photon to conversion efficiency, which is significantly higher than that of the CdS/ZnO nanorod array electrodes. The high charge separation between the electrons and holes at the interfaces of the heterojunction structure results from the specific band energy structure of the photoanode materials, and the unique high conductivity of the CdO layer is attributed to the suppression of electron-hole recombination; this suppression enhances the photocurrent density of the CdO/CdS/ZnO nanorod arrays. The photoresponse of the electrodes in an electrolytic solution without sacrificial agents indicated that the CdO layer also has the ability to suppress the well-known photocorrosive behavior of CdS/ZnO nanorods. PMID:25324138

Van, Thanh Khue; Pham, Long Quoc; Kim, Do Yoon; Zheng, Jin You; Kim, Dokyoung; Pawar, Amol U; Kang, Young Soo

2014-12-01

393

High-performance hierarchical LiNi1/3Mn1/3Co1/3O2 microspheres synthesized via a facile template-sacrificial route  

International Nuclear Information System (INIS)

Highlights: • Microsphere hierarchical LiNi1/3Mn1/3Co1/3O2 was fabricated. • A facile in situ route with MnO2 as the sacrificial template was developed. • Conventional co-precipitate synthesis method was compared. • The hierarchical microsphere sample exhibits superior electrochemical performance. -- Abstract: LiNi1/3Mn1/3Co1/3O2 microspheres have been successfully synthesized via a facile in situ route with MnO2 as the sacrificial template. The as-obtained sample shows a unique nano/micro-hierarchical structure. As a cathode material for lithium-ion battery, the sample exhibits excellent electrochemical performance with higher capacity, superior cycling stability and rate capability as compared with that prepared by conventional co-precipitate reaction method. The discharge specific capacities for the first cycle are 196, 187, 182 and 176 mA h g?1 at 0.1, 0.2, 0.5 and 1 C, respectively. The superior performance can be ascribed to the unique microstructure with numerous nanosized primary particles that can provide rapid pathway for Li+ and e? diffusion, and facilitate the penetration of the electrolyte

394

High-performance hierarchical LiNi{sub 1/3}Mn{sub 1/3}Co{sub 1/3}O{sub 2} microspheres synthesized via a facile template-sacrificial route  

Energy Technology Data Exchange (ETDEWEB)

Highlights: • Microsphere hierarchical LiNi{sub 1/3}Mn{sub 1/3}Co{sub 1/3}O{sub 2} was fabricated. • A facile in situ route with MnO{sub 2} as the sacrificial template was developed. • Conventional co-precipitate synthesis method was compared. • The hierarchical microsphere sample exhibits superior electrochemical performance. -- Abstract: LiNi{sub 1/3}Mn{sub 1/3}Co{sub 1/3}O{sub 2} microspheres have been successfully synthesized via a facile in situ route with MnO{sub 2} as the sacrificial template. The as-obtained sample shows a unique nano/micro-hierarchical structure. As a cathode material for lithium-ion battery, the sample exhibits excellent electrochemical performance with higher capacity, superior cycling stability and rate capability as compared with that prepared by conventional co-precipitate reaction method. The discharge specific capacities for the first cycle are 196, 187, 182 and 176 mA h g{sup ?1} at 0.1, 0.2, 0.5 and 1 C, respectively. The superior performance can be ascribed to the unique microstructure with numerous nanosized primary particles that can provide rapid pathway for Li{sup +} and e{sup ?} diffusion, and facilitate the penetration of the electrolyte.

Xiong, Wen; Jiang, Yan; Yang, Ze [Key Laboratory for Advanced Battery Materials and System (Ministry of Education), School of Materials Science and Engineering, Huazhong University of Science and Technology, Wuhan, Hubei 430074 (China); Li, Dinggen [School of Energy and Power Engineering, Huazhong University of Science and Technology, Wuhan, Hubei 430074 (China); Huang, Yunhui, E-mail: huangyh@mail.hust.edu.cn [Key Laboratory for Advanced Battery Materials and System (Ministry of Education), School of Materials Science and Engineering, Huazhong University of Science and Technology, Wuhan, Hubei 430074 (China)

2014-03-15

395

Colloidal processing and CO2 capture performance of sacrificially templated zeolite monoliths  

International Nuclear Information System (INIS)

Highlights: ? We demonstrate structuring of hierarchically porous zeolite monoliths. ? Structured zeolite monoliths show high CO2 adsorption capacity. ? Addition of 5 wt% of kaolin to zeolite monoliths ensures a mechanical stability. ? Cyclic adsorption and regeneration show that structured monoliths are robust. -- Abstract: Sacrificial templating of suspension cast and subsequently thermally treated zeolite monoliths with glassy carbon spheres and fibers yielded zeolite 13X and silicalite-1 monoliths with macroporosities up to 50 vol%. Homogeneous distribution of the macroporosity in hierarchically porous monoliths was obtained by tailoring the surface chemistry of the carbon particles by polyelectrolyte-assisted adsorption of zeolite particles. The effect of amount of kaolin binder and temperature for the thermal treatment on the monoliths strength, surface area and CO2 uptake was studied by diametral compression tests, electron microscopy, X-ray diffraction and gas adsorption. Cyclic adsorption and regeneration measurements showed that zeolite 13X monoliths display a high CO2 uptake while the silicalite-1 monoliths could be regenerated with a relatively low energy penalty.

396

Synthesis of porous silica hollow spheres using sacrificial template for drug delivery applications  

Directory of Open Access Journals (Sweden)

Full Text Available In this work, we report on the synthesis of SiO2 hollow spheres using carbon nanospheres as the sacrificial template by hydrothermal method. The synthesized substrates are in a spherical morphology and uniform size distribution. The effects of hydrothermal process, concentration and the reaction temperature were optimized during synthesis of carbon nanospheres. Infrared spectroscopy (IR, and scanning electronic microscopy (SEM methods were used for identification of the synthesized products. The synthesized SiO2 nanospheres were used as drug carrier to investigate in vitro release behavior of monoterpenic phenol isomers, carvacrol and thymol, in simulated body fluid (SBF. Ultraviolet-visible spectroscopy (UV-vis method was carried out to determine the amount of the drugs entrapped in the carrier. The results indicated that SiO2 nanospheres have high ability to adsorb the drugs and there is no need for adjusting the pH during the adsorption process. The drug release profile shows a three stages pattern and indicates a delayed release action.

Rasoul Safdari

2014-06-01

397

Electrochemical treatment of Orange II dye solution-Use of aluminum sacrificial electrodes and floc characterization  

International Nuclear Information System (INIS)

Electrocoagulation (EC) of Orange II dye in a flow through cell with aluminum as sacrificial electrodes was carried out under varying conditions of dye concentration, current density, flow rate, conductivity, and the initial pH of the solution in order to optimize the operating parameters for maximum benefits. Maximum removal efficiency of 94.5% was obtained at the following conditions: dye concentration = 10 ppm, current density = 160 A/m2, initial pH 6.5, conductance = 7.1 mS/cm, flow rate = 350 mL/min, and concentration of added NaCl = 4.0 g/L of dye solution. The EC-floc was characterized using Fourier transform infrared spectroscopy, scanning electron microscopy/energy dispersive X-ray spectroscopy, and powder X-ray diffraction techniques. The removal mechanism has been proposed that is in compliance with the Pourbaix diagram, solubility curve of aluminum oxides/hydroxides, and physico-chemical properties of the EC-floc.

398

Oxidant-dependent switching between reversible and sacrificial oxidation pathways for Bacillus subtilis OhrR.  

Science.gov (United States)

The Bacillus subtilis OhrR protein functions as a transcriptional repressor of the inducible peroxidase, OhrA. Derepression is mediated by the organic-peroxide selective oxidation of an active site cysteine (C15). In the presence of cumene hydroperoxide (CHP), oxidation of OhrR leads to a sulphenic acid intermediate which reacts to form either a mixed-disulphide or a protein sulphenamide. These inactive forms of OhrR can be reactivated by thiol-disulphide exchange reactions allowing restoration of repression. Here, we demonstrate that linoleic acid hydroperoxide (LHP) is a potent oxidant for OhrR and even low levels lead to overoxidation of OhrR to cysteine sulphinic (and sulphonic) acid derivatives. Kinetic competition experiments indicate that further oxidation of the initial OhrR sulphenate product occurs at least 100-fold more rapidly with LHP than with CHP. Thus, depending on the oxidant, OhrR can be either reversibly oxidized or can instead function as a sacrificial regulator. PMID:18363800

Soonsanga, Sumarin; Lee, Jin-Won; Helmann, John D

2008-05-01

399

Preparation of titanium dioxide nanoparticles from electrocoagulated sludge using sacrificial titanium electrodes.  

Science.gov (United States)

A comprehensive investigation of electrocoagulation using sacrificial titanium (Ti) electrodes in wastewater was carried out. The effects of specific process variables, such as initial pH, mixing, current density, initial organic loading, and ionic/electrolyte strength were first optimized to produce recyclable Ti-based sludge. The sludge was incinerated at 600 degrees C to produce functional TiO(2) photocatalyst. X-ray diffraction analysis revealed that TiO(2) produced at optimum electrocoagulation conditions was mostly anatase structure. The specific surface area of the synthesized TiO(2) photocatalyst was higher than that of the commercially available and widely used Degussa P-25 TiO(2). Furthermore, energy dispersive X-ray and X-ray photoelectron spectroscopy analyses showed that in additional to titanium and oxygen, this photocatalyst is also composed of carbon and phosphorus. These elements were mainly doped as a substitute site for the oxygen atom. Transmission electron microscopy images exhibited sharply edged nanorods, round nanoparticles, and nanotubes with nonuniform shapes showing some structural defects. Photodecomposition of gaseous acetaldehyde by this photocatalyst was also conducted under UV and visible light irradiation to study the photocatalytic properties of the doped TiO(2) photocatalyst. While no photocatalytic activity was observed under visible light irradiation, this doped TiO(2) photocatalyst exhibited high photocatalytic activity under UV light. PMID:20560597

Shon, H K; Phuntsho, S; Vigneswaran, S; Kandasamy, J; Nghiem, L D; Kim, G J; Kim, J B; Kim, J-H

2010-07-15

400

Extension and optimization of a three-layer method for the estimation of thermal conductivity of super-insulating materials  

Science.gov (United States)

The three-layer method is a characterization method dedicated to the measurement of the thermal conductivity of small samples made out of insulating or super-insulating materials. It is based on the transient recording of the mean temperatures of two brass plates placed, respectively, above and under the sample, one of them being heated. In case of a super insulating material, the rate of heat flow from the heated to the unheated plate through the surrounding air is not negligible with respect to the rate of heat flow through the sample. It is shown that introduction of a simple parallel thermal resistance allows taking this flow of heat into account. An analytical model, based on a new quadrupolar approach, was developed to estimate this resistance considered further as a known parameter in the estimation process. An experimental study was carried out to characterize samples whose thermal conductivities have been measured previously with another method. The deviation of the estimated thermal conductivities from these reference values with respect to the three-layer method results reaches 29% without considering parallel heat flow but is lower than 2% using the new model.

Bahrani, Seyed Amir; Jannot, Yves; Degiovanni, Alain

2014-10-01

 
 
 
 
401

A green synthesis of a layered titanate, potassium lithium titanate; lower temperature solid-state reaction and improved materials performance  

International Nuclear Information System (INIS)

A layered titanate, potassium lithium titanate, with the size range from 0.1 to 30 µm was prepared to show the effects of the particle size on the materials performance. The potassium lithium titanate was prepared by solid-state reaction as reported previously, where the reaction temperature was varied. The reported temperature for the titanate preparation was higher than 800 °C, though 600 °C is good enough to obtain single-phase potassium lithium titanate. The lower temperature synthesis is cost effective and the product exhibit better performance as photocatalysts due to surface reactivity. - Graphical abstract: Finite particle of a layered titanate, potassium lithium titanate, was prepared by solid-state reaction at lower temperature to show modified materials performance. Display Omitted - Highlights: • Potassium lithium titanate was prepared by solid-state reaction. • Lower temperature reaction resulted in smaller sized particles of titanate. • 600 °C was good enough to obtain single phased potassium lithium titanate. • The product exhibited better performance as photocatalyst

402

Influence of oxide layers on the cladding material in a liquid lead environment: a comparison between MATRA and TRACE  

Energy Technology Data Exchange (ETDEWEB)

The liquid lead-cooled fast reactor (LFR) is one design proposal for further investigations in the frame of the Generation IV project. Due to the high melting point of lead (327 deg. C), the temperature of operation is in the range of 400 to 500 deg. C. This requires a cladding material, which sustains high temperatures over long time periods. The proposed material will be the ferritic-martensitic steel T-91. One drawback of working in a liquid lead environment is the high solubility of metals in it. A protective oxide layer is one option to face the corrosion issue but has the disadvantage of a low thermal conductivity, which increases the cladding temperature. The layout of the fuel assembly (FA) of the LFR is determined to be either an open quadratic array or a hexagonal design with a wrapper. Both designs influence the thermohydraulic of the core since the heat transfer depends on the geometry of the cooling channel. Investigations of the influence of the oxide layer and of the impact of the heat transfer were done for an open quadratic FA. For the assessment of the above mentioned challenges, the subchannel code MATRA and the system code TRACE were extended and applied. Corresponding results are here compared. (authors)

Jaeger, Wadim; Sanchez Espinoza, Victor H. [Forschungszentrum Karlsruhe GmbH, Institute for Reactor Safety, Eggenstein-Leopoldshafe (Germany)

2008-07-01

403

Influence of oxide layers on the cladding material in a liquid lead environment: a comparison between MATRA and TRACE  

International Nuclear Information System (INIS)

The liquid lead-cooled fast reactor (LFR) is one design proposal for further investigations in the frame of the Generation IV project. Due to the high melting point of lead (327 deg. C), the temperature of operation is in the range of 400 to 500 deg. C. This requires a cladding material, which sustains high temperatures over long time periods. The proposed material will be the ferritic-martensitic steel T-91. One drawback of working in a liquid lead environment is the high solubility of metals in it. A protective oxide layer is one option to face the corrosion issue but has the disadvantage of a low thermal conductivity, which increases the cladding temperature. The layout of the fuel assembly (FA) of the LFR is determined to be either an open quadratic array or a hexagonal design with a wrapper. Both designs influence the thermohydraulic of the core since the heat transfer depends on the geometry of the cooling channel. Investigations of the influence of the oxide layer and of the impact of the heat transfer were done for an open quadratic FA. For the assessment of the above mentioned challenges, the subchannel code MATRA and the system code TRACE were extended and applied. Corresponding results are here compared. (authors)