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

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

3

Tuneable Capacitor based on dual picks profile of the sacrificial layer  

Digital Repository Infrastructure Vision for European Research (DRIVER)

In this paper, we present a novel dual gap tuneable capacitor process based on the profile of the sacrificial layer. This profile involves a tri-layer photo-resist process with only one mask level. This realization is based on a special profile of the sacrificial layer designed by two picks. The mechanism of the sacrificial layer realisation is dependent on resist thickness, resist formulation (viscosity, type of polymer and/or solvent, additives...), design of the patterned...

Soulimane, S.; Casset, F.; Chapuis, F.; Charvet, P. -l; Ai?d, M.

2008-01-01

4

Use of Amphoteric Copolymer Films as Sacrificial Layers for Constructing Free-Standing Layer-by-Layer Films  

Directory of Open Access Journals (Sweden)

Full Text Available The present paper reports the use of an amphoteric copolymer, poly(diallylamine-co-maleic acid (PDAMA, as a component of precursor layers (or sacrificial layers for constructing free-standing layer-by-layer (LbL films. A PDAMA-poly(styrenesulfonate (PSS film or PDAMA-poly(dimethyldiallylammonium chloride (PDDA film was coated on the surface of a quartz slide at pH 4.0 or 8.0, respectively, as a sacrificial layer that can be removed by changing the pH. The surface of the sacrificial layer was further covered with LbL films composed of poly(allylamine hydrochloride (PAH and PSS. The PAH-PSS films were released from the substrate upon immersing the film-coated quartz slide in acidic or neutral/basic solution, respectively, as a result of the pH-induced dissolution of the PDAMA-PDDA or PDAMA-PSS sacrificial layer. Thus, PDAMA-based sacrificial layers have been demonstrated to dissolve in both acidic and neutral solutions, depending on the type of counter polymer. The thicknesses of the sacrificial layers and released LbL films are crucial factors for constructing free-standing LbL films. The releasing kinetics also depended on the thickness of the crucial layers. The free-standing PAH-PSS films obtained were stable in water or in air in the dry state. PDAMA-based sacrificial layers may be useful in constructing free-standing LbL films containing biomolecules with limited pH stability.

Baozhen Wang

2013-06-01

5

Metallization and Biopatterning on Ultra-Flexible Substrates via Dextran Sacrificial Layers  

Science.gov (United States)

Micro-patterning tools adopted from the semiconductor industry have mostly been optimized to pattern features onto rigid silicon and glass substrates, however, recently the need to pattern on soft substrates has been identified in simulating cellular environments or developing flexible biosensors. We present a simple method of introducing a variety of patterned materials and structures into ultra-flexible polydimethylsiloxane (PDMS) layers (elastic moduli down to 3 kPa) utilizing water-soluble dextran sacrificial thin films. Dextran films provided a stable template for photolithography, metal deposition, particle adsorption, and protein stamping. These materials and structures (including dextran itself) were then readily transferrable to an elastomer surface following PDMS (10 to 70?1 base to crosslinker ratios) curing over the patterned dextran layer and after sacrificial etch of the dextran in water. We demonstrate that this simple and straightforward approach can controllably manipulate surface wetting and protein adsorption characteristics of PDMS, covalently link protein patterns for stable cell patterning, generate composite structures of epoxy or particles for study of cell mechanical response, and stably integrate certain metals with use of vinyl molecular adhesives. This method is compatible over the complete moduli range of PDMS, and potentially generalizable over a host of additional micro- and nano-structures and materials. PMID:25153326

Tseng, Peter; Pushkarsky, Ivan; Di Carlo, Dino

2014-01-01

6

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

7

Tuneable Capacitor based on dual picks profile of the sacrificial layer  

CERN Document Server

In this paper, we present a novel dual gap tuneable capacitor process based on the profile of the sacrificial layer. This profile involves a tri-layer photo-resist process with only one mask level. This realization is based on a special profile of the sacrificial layer designed by two picks. The mechanism of the sacrificial layer realisation is dependent on resist thickness, resist formulation (viscosity, type of polymer and/or solvent, additives...), design of the patterned layer (size or width) and the conditions under which this layer is prepared: thermal treatment, etch back processes... In this communication we demonstrate influence of the later parameters and discuss how a dual pick profile was achieved.

Soulimane, S; Chapuis, F; Charvet, P -L; aïd, M

2008-01-01

8

Phosphorus diffusion gettering process of multicrystalline silicon using a sacrificial porous silicon layer  

Digital Repository Infrastructure Vision for European Research (DRIVER)

The aims of this work are to getter undesirable impurities from low-cost multicrystalline silicon (mc-Si) wafers and then enhance their electronic properties. We used an efficient process which consists of applying phosphorus diffusion into a sacrificial porous silicon (PS) layer in which the gettered impurities have been trapped after the heat treatment. As we have expected, after removing the phosphorus-rich PS layer, the electrical properties of the mc-Si wafers were significantly improved...

Lotfi, Derbali; Hatem, Ezzaouia

2012-01-01

9

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.

Andreasen, Jens Wenzel; Breiby, Dag Werner

2009-01-01

10

Electroassisted transfer of vertical silicon wire arrays using a sacrificial porous silicon layer.  

Science.gov (United States)

An electroassisted method is developed to transfer silicon (Si) wire arrays from the Si wafers on which they are grown to other substrates while maintaining their original properties and vertical alignment. First, electroassisted etching is used to form a sacrificial porous Si layer underneath the Si wires. Second, the porous Si layer is separated from the Si wafer by electropolishing, enabling the separation and transfer of the Si wires. The method is further expanded to develop a current-induced metal-assisted chemical etching technique for the facile and rapid synthesis of Si nanowires with axially modulated porosity. PMID:23919596

Weisse, Jeffrey M; Lee, Chi Hwan; Kim, Dong Rip; Cai, Lili; Rao, Pratap M; Zheng, Xiaolin

2013-09-11

11

Methods for making thin layers of crystalline materials  

Science.gov (United States)

Methods for making growth templates for the epitaxial growth of compound semiconductors and other materials are provided. The growth templates are thin layers of single-crystalline materials that are themselves grown epitaxially on a substrate that includes a thin layer of sacrificial material. The thin layer of sacrificial material, which creates a coherent strain in the single-crystalline material as it is grown thereon, includes one or more suspended sections and one or more supported sections.

Lagally, Max G; Paskiewicz, Deborah M; Tanto, Boy

2013-07-23

12

Fabrication of Relaxer-Based Piezoelectric Energy Harvesters Using a Sacrificial Poly-Si Seeding Layer  

Science.gov (United States)

The effect of a polycrystalline silicon (poly-Si) seeding layer on the properties of relaxor Pb(Zr0.53,Ti0.47)O3-Pb(Zn1/3,Nb2/3)O3 (PZT-PZN) thin films and energy-harvesting cantilevers was studied. We deposited thin films of the relaxor on two substrates, with and without a poly-Si seeding layer. The seeding layer, which also served as a sacrificial layer to facilitate cantilever release, was found to improve morphology, phase purity, crystal orientation, and electrical properties. We attributed these results to reduction of the number of nucleation sites and, therefore, to an increase in relaxor film grain size. The areal power density of the wet-based released harvester was measured. The power density output of the energy harvester with this relaxor composition and the poly-Si seeding layer was 325 ?W/cm2.

Fuentes-Fernandez, E. M. A.; Salomon-Preciado, A. M.; Gnade, B. E.; Quevedo-Lopez, M. A.; Shah, P.; Alshareef, H. N.

2014-11-01

13

A Full-dry Processing Technique from Sacrificial Layer Etching to Water-repellent Coating  

Science.gov (United States)

A new full-dry processing method has been developed that includes a new sacrificial layer dry etching technique, which enables the microscopic structures used for microsensors to be released from silicon substrates with high repeatability, and a new water-repellent dry coating technique, which prevents the released structures from sticking to substrates during operation. The usefulness of this full-dry processing method from etching to coating, with respect to the length of releasable cantilevers, was evaluated by comparison with the conventional wet method. It was confirmed that the full-dry processing method permits sustainable cantilevers to be about three times longer than those released using the conventional wet method.

Shimaoka, Keiichi; Sakata, Jiro; Mitsushima, Yasuichi

14

Altering the dewetting characteristics of ultrathin gold and silver films using a sacrificial antimony layer  

International Nuclear Information System (INIS)

Solid state dewetting of ultrathin films is the most straightforward means of fabricating substrate-supported noble metal nanostructures. This assembly process is, however, quite inflexible, yielding either densely packed smaller structures or widely spaced larger structures. Here, we demonstrate the utility of introducing a sacrificial antimony layer between the substrate and noble metal overlayer. We observe an agglomeration process which is radically altered by the concurrent sublimation of antimony. In stark contrast with conventional dewetting, where the thickness of the deposited metal film determines the characteristic length scales of the assembly process, it is the thickness of the sacrificial antimony layer which dictates both the nanoparticle size and interparticle spacing. The result is a far more flexible self-assembly process where the nanoparticle size and areal density can be varied widely. Demonstrations show nanoparticle areal densities which are varied over four orders of magnitude assembled from the identical gold layer thickness, where the accompanying changes to nanostructure size see a systematic shift in the wavelength of the localized surface plasmon resonance. As a pliable self-assembly process, it offers the opportunity to tailor the properties of an ensemble of nanostructures to meet the needs of specific applications. (paper)

15

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

Science.gov (United States)

Throughout this investigation, experiments on laser ablation with silicon (Si) wafers have been performed using silicon nitride (Si 3N 4) as a sacrificial layer to find the optimal fluence capable of removing the Si 3N 4, 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 Si 3N 4 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).

Lerner, B.; Perez, M. S.; Toro, C.; Lasorsa, C.; Rinaldi, C. A.; Boselli, A.; Lamagna, A.

2012-01-01

16

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

17

Phosphorus diffusion gettering process of multicrystalline silicon using a sacrificial porous silicon layer  

Science.gov (United States)

The aims of this work are to getter undesirable impurities from low-cost multicrystalline silicon (mc-Si) wafers and then enhance their electronic properties. We used an efficient process which consists of applying phosphorus diffusion into a sacrificial porous silicon (PS) layer in which the gettered impurities have been trapped after the heat treatment. As we have expected, after removing the phosphorus-rich PS layer, the electrical properties of the mc-Si wafers were significantly improved. The PS layers, realized on both sides of the mc-Si substrates, were formed by the stain-etching technique. The phosphorus treatment was achieved using a liquid POCl3-based source on both sides of the mc-Si wafers. The realized phosphorus/PS/Si/PS/phosphorus structures were annealed at a temperature ranging between 700°C and 950°C under a controlled O2 atmosphere, which allows phosphorus to diffuse throughout the PS layers and to getter eventual metal impurities towards the phosphorus-doped PS layer. The effect of this gettering procedure was investigated by means of internal quantum efficiency and the dark current-voltage ( I- V) characteristics. The minority carrier lifetime measurements were made using a WTC-120 photoconductance lifetime tester. The serial resistance and the shunt resistance carried out from the dark I- V curves confirm this gettering-related solar cell improvement. It has been shown that the photovoltaic parameters of the gettered silicon solar cells were improved with regard to the ungettered one, which proves the beneficial effect of this gettering process on the conversion efficiency of the multicrystalline silicon solar cells.

Lotfi, Derbali; Hatem, Ezzaouia

2012-07-01

18

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

19

Screen printing of a capacitive cantilever-based motion sensor on fabric using a novel sacrificial layer process for smart fabric applications  

Science.gov (United States)

Free-standing cantilevers have been fabricated by screen printing sacrificial and structural layers onto a standard polyester cotton fabric. By printing additional conductive layers, a complete capacitive motion sensor on fabric using only screen printing has been fabricated. This type of free-standing structure cannot currently be fabricated using conventional fabric manufacturing processes. In addition, compared to conventional smart fabric fabrication processes (e.g. weaving and knitting), screen printing offers the advantages of geometric design flexibility and the ability to simultaneously print multiple devices of the same or different designs. Furthermore, a range of active inks exists from the printed electronics industry which can potentially be applied to create many types of smart fabric. Four cantilevers with different lengths have been printed on fabric using a five-layer structure with a sacrificial material underneath the cantilever. The sacrificial layer is subsequently removed at 160 °C for 30 min to achieve a freestanding cantilever above the fabric. Two silver electrodes, one on top of the cantilever and the other on top of the fabric, are used to capacitively detect the movement of the cantilever. In this way, an entirely printed motion sensor is produced on a standard fabric. The motion sensor was initially tested on an electromechanical shaker rig at a low frequency range to examine the linearity and the sensitivity of each design. Then, these sensors were individually attached to a moving human forearm to evaluate more representative results. A commercial accelerometer (Microstrain G-link) was mounted alongside for comparison. The printed sensors have a similar motion response to the commercial accelerometer, demonstrating the potential of a printed smart fabric motion sensor for use in intelligent clothing applications.

Wei, Yang; Torah, Russel; Yang, Kai; Beeby, Steve; Tudor, John

2013-07-01

20

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

 
 
 
 
21

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

22

Electric double layer effect in a nano-scale SiO2 sacrificial layer etching process and its application in nanowire fabrication  

Science.gov (United States)

Process controllability has become one of the key factors for utilizing micro-scale processes in nanofabrication. Sacrificial layer technology especially should be carefully handled to avoid excessive etching of nano-scale device structures. In this work, the etching behavior of a buffered HF (BHF) solution for thermally-grown silicon dioxide sacrificial layers with thicknesses in the range of 22 to 112.7 nm was characterized. For the first time, accelerated limiting of etching was reported for sub-50 nm layers. However, for thicker ones (more than 50 nm), almost constant rate isotropic etching was observed. A detailed discussion revealed that the conventional diffusion-induced etching model was no longer valid in such a minute structure, and the electric double layer (EDL) effect instead, was likely to dominate. Simulation was carried out to investigate the influence of the electric potential generated by an interfacial charge layer upon reactive ions in the etchant, which was proved to be consistent with the experimental results. By using such nano-scale sacrificial layer technology, combined with anisotropic silicon etching, cost-effective and stable production of silicon nanowires (SiNWs) was accomplished, with a uniform width down to 100 nm, respectively. Reliable electrical connection was also achieved by smooth transitions from the nanowire to single crystal silicon electrodes, which further confirmed the potential of this highly controllable process.

Gong, Yibin; Dai, Pengfei; Gao, Anran; Li, Tie; Zhou, Ping; Wang, Yuelin

2010-10-01

23

Sodium Exposure Tests on Limestone Concrete Used as Sacrificial Protection Layer in FBR  

International Nuclear Information System (INIS)

Hot sodium coming in contact with structural concrete in case of sodium leak in FBR system cause damage as a result of thermo-chemical attack by burning sodium. In addition, release of free and bound water from concrete leads to generation of hydrogen gas, which is explosive in nature. Hence limestone concrete, as sacrificial layer on the structural concrete in FBR, needs to be qualified. Four concrete blocks of dimension 600 mm x 600 mm x 300 mm with 300 mm x 300 mm x 150 mm cavity were cast and subjected to controlled sodium exposure tests. They have composition of ordinary portland cement, water, fine and coarse aggregate of limestone in the ratio of 1: 0.58: 2.547: 3.817. These blocks were subjected to preliminary inspection by ultrasonic pulse velocity technique and rebound hammer tests. Each block was exposed for 30 minutes to about 12 kg of liquid sodium (? 120 mm liquid column) at 550 deg. C in open air, after which sodium was sucked back from the cavity of the concrete block into a sodium tank. On-line temperature monitoring was carried out at strategic locations of sodium pool and concrete block. After removing sodium from the cavity and cleaning the surfaces, rebound hammer testing was carried out on each concrete block at the same locations where data were taken earlier at pre-exposed stage. The statistical analysis of rebound hammer data revealed that one of the concrete block alone has undergone damage to the extent of 16%. The loss of mass occurred for all the four blocks varied from 0.6 to 2.4% due to release of water during the test duration. Chemical analysis of sodium in concrete samples collected from cavity floor of each block helped in generation of depth profiles of sodium monoxide concentration for each block. From this it is concluded that a bulk penetration of sodium up to 30 mm depth has taken place. However it was also observed that at few local spots, sodium penetrated into concrete up to 50 mm. Cylindrical core samples of 50 mm x 150 mm long were obtained from the exposed cavity and tested for compressive strength and longitudinal ultrasonic pulse velocity (UPV). These are compared with core samples obtained from concrete cubes used as standard reference. The average reduction in UPV and compressive strength were 7% and 29% respectively indicating marginal degradation in mechanical properties of sodium-exposed concrete. (authors)

24

Feasibility study of barium fluoride films as a sacrificial layer for patterning of ZnO nanowire arrays  

Science.gov (United States)

Vertical aligned ZnO nanowires were grown by metal-organic chemical vapor deposition technique on Si substrate. X-ray diffraction patterns and the high-resolution transmission electron microscopy confirmed the single crystalline growth of the ZnO nanowires along [0 0 0 1] direction. In another experiment, BaF 2 films were deposited on silicon substrate by thermal evaporation. The BaF 2 films show polycrystalline nature along with a granular surface morphology. Based on the solubility of BaF 2 film in cold water, BaF 2 layer was used as a sacrificial layer for the patterning of ZnO nanowire arrays. A sharp edge was obtained between the hexagonal pattern and the surrounding nanowires, which is suitable for micropatterning of ZnO nanowires for electronic devices.

Kar, J. P.; Choi, J. H.; Myoung, J. M.

2009-04-01

25

Synthesis and characterization of photodefinable polycarbonates for use as sacrificial materials in the fabrication of microfluidic devices  

Science.gov (United States)

A fabrication technique recently developed at Georgia Institute of Technology involving thermally sacrificial polymeric materials allows for fabrication of microfluidic devices with greater degrees of functionality (i.e., fully integrated, complex, multi-level fluidic systems with functional valves, pumping systems, and other micro- electromechanical system [MEMS] components). In this method, thermally sacrificial polymers are coated onto a substrate and patterned into the shape of the desired channels and devices. These polymeric structures are then over-coated with a permanent structural material such as an inorganic glass or polymer. These steps can be repeated to produce complex, three-dimensional systems. Once the device build-up is complete, the structure is heated to a temperature at which the sacrificial polymer slowly decomposes, thus leaving behind the desired open-channeled structures. This process was first developed using functionalized polynorbornenes that decompose at temperatures in the range of 425 degree(s)C. In order to make this approach compatible with a wider range of substrates and structural materials, polymers with lower decomposition temperatures were desired. Polycarbonates were identified as a class of polymers with the desired lower decomposition temperatures (200- 300 degree(s)C). A disadvantage of commercially available polycarbonates, like poly (propylene carbonate), is that they have low glass transition temperatures (Tgapproximately equals 40 degree(s)C). This introduces several problems, including pattern deformation at elevated processing temperatures. Also, a significant number of process steps are required to pattern the channel structures using simple polymer materials. Therefore, this paper will describe recent results of work on photodefinable polycarbonates with improved thermal properties. Utilizing a polymer that can be patterned directly by conventional lithography greatly simplifies the fabrication process and eliminates the need for the plasma etch steps required in the original process. Results of the synthesis and characterization of polycarbonates patterned with the use of a photoacid generator, thus exploiting the acid-catalyzed thermolysis of polycarbonates, will be presented.

White, Celesta E.; Henderson, Clifford L.

2002-07-01

26

Fabrication of a three-layer SU-8 mould with inverted T-shaped cavities based on a sacrificial photoresist layer technique.  

Science.gov (United States)

A novel method for fabricating a three-layer SU-8 mould with inverted T-shaped cavities is presented. The first two SU-8 layers were spin coated and exposed separately, and simultaneously developed to fabricate the bottom and the horizontal part of the inverted T-shaped cavity. Then, a positive photoresist was filled into the cavity, and a wet lapping process was performed to remove the excess photoresist and make a temporary substrate. The third SU-8 layer was spin coated on the temporary substrate to make the vertical part of the inverted T-shaped cavity. The sacrificial photoresist layer can prevent the first two SU-8 layers from being secondly exposed, and make a temporary substrate for the third SU-8 layer at the same time. Moreover, the photoresist can be easily removed with the development of the third SU-8 layer. A polydimethylsiloxane (PDMS) microchip with arrays of T-shaped cantilevers for studying the mechanics of cells was fabricated by using the SU-8 mould. PMID:24850230

Liu, Junshan; Zhang, Dong; Sha, Baoyong; Yin, Penghe; Xu, Zheng; Liu, Chong; Wang, Liding; Xu, Feng; Wang, Lin

2014-10-01

27

Fabrication of polymer micro-devices based on organic sacrificial pastes  

Digital Repository Infrastructure Vision for European Research (DRIVER)

We investigate in this work the fabrication of polymer micro-fluidic and micro-mechanical devices based on sublimable compounds as sacrificial layers, using a thick-film screen-printing deposition process. Fabrication of printed polymer microstructures featuring properties such as low cost, transparency and biocompatibility is particularly attractive and suitable for disposable biomedical devices. Channel, cavities and spacings for micro-devices are first defined by sacrificial material layer...

Serra, Nathalie; Maeder, Thomas; Gentsch, Olivier; Ryser, Peter

2010-01-01

28

Buckle-driven delamination of hydrophobic micro-, nano-, and heterostructured membranes without a sacrificial layer  

Science.gov (United States)

A fabrication method, based on thin film buckling, is demonstrated to form unique membranes that can be used for applications in optics and biosensing. This method should be applicable to a variety of material systems, which, along with its simplicity and compatibility with different film architectures, allows for widespread implementation.A fabrication method, based on thin film buckling, is demonstrated to form unique membranes that can be used for applications in optics and biosensing. This method should be applicable to a variety of material systems, which, along with its simplicity and compatibility with different film architectures, allows for widespread implementation. Electronic supplementary information (ESI) available: Monolayer characterization and details; morphological parameters of the membranes; diffraction pattern images; rigorous coupled wave analysis; pattern transfer fidelity; experimental details. See DOI: 10.1039/c3nr03933a

Larsen, George K.; Zhao, Yiping

2013-10-01

29

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

30

Comparison of solvent and sacrificial volume-material-based lamination processes of low-temperature co-fired ceramics tapes  

Science.gov (United States)

The lamination process determines the quality of low temperature co-fired ceramics (LTCC) based spatial structures. This paper compares two methods of the microchannel fabrication process in zero-shrinkage LTCC substrates. The first one is based on a two-step lamination process and uses various sacrificial volume materials (SVM). The second one is based on the cold chemical lamination (CCL) process. On the one hand, the SVM gives the possibility of decreasing the deformation of the three-dimensional (3D) structures during the lamination process. The channel volume is filled with a special fugitive material. It protects the spatial structure from deformation during lamination, and evaporates completely during the co-firing process. The bonding quality and strength depend strongly on the fugitive phase type. On the other hand, the CCL is a solvent-based method. It is another alternative for bonding of green ceramic tapes. A special liquid agent is screen printed on the green tape, which melts the tape surface. Then the tapes are stacked and compressed at room temperature by a printing roll. The influence of each method on the microchannel geometry is analyzed in this paper. The resulting structures' bonding quality and mechanical properties are examined by a scanning electron microscope (SEM).

Malecha, Karol; Jurków, Dominik; Golonka, Leszek J.

2009-06-01

31

Comparison of solvent and sacrificial volume-material-based lamination processes of low-temperature co-fired ceramics tapes  

International Nuclear Information System (INIS)

The lamination process determines the quality of low temperature co-fired ceramics (LTCC) based spatial structures. This paper compares two methods of the microchannel fabrication process in zero-shrinkage LTCC substrates. The first one is based on a two-step lamination process and uses various sacrificial volume materials (SVM). The second one is based on the cold chemical lamination (CCL) process. On the one hand, the SVM gives the possibility of decreasing the deformation of the three-dimensional (3D) structures during the lamination process. The channel volume is filled with a special fugitive material. It protects the spatial structure from deformation during lamination, and evaporates completely during the co-firing process. The bonding quality and strength depend strongly on the fugitive phase type. On the other hand, the CCL is a solvent-based method. It is another alternative for bonding of green ceramic tapes. A special liquid agent is screen printed on the green tape, which melts the tape surface. Then the tapes are stacked and compressed at room temperature by a printing roll. The influence of each method on the microchannel geometry is analyzed in this paper. The resulting structures' bonding quality and mechanical properties are examined by a scanning electron microscope (SEM)

32

Illumination-dependent HF Etching of AlAs Sacrificial Layers for the Formation of ``Rolled Up'' Nanotubes from Strained InGaAs/GaAs Films  

Science.gov (United States)

"Rolled-up" nanostructures formed from lattice mismatched III-V heterojunction films by taking advantage of a strain-induced self-rolling mechanism represent a useful type of building blocks for nanotechnology, with possible applications in high-speed microelectronic and optoelectronic devices. This work investigated the effect of illumination on the hydrofluoric acid etching of AlAs sacrificial layers with systematically varied thicknesses in order to release and roll up MBE grown InGaAs/GaAs bilayers. Based on this "etch suppression effect" (ESE), we propose an illumination-assisted technique that offers an advantage over other methods of rolling up nano-objects on a substrate from inherently strained films because it allows control over the positioning of rolled-up micro- and nanotubes independently from lithographic methods. For thicknesses of AlAs below 10 nm, we found two etching regimes for the area under illumination: one at low illumination intensities, in which the etching and releasing proceeds as expected and one at higher intensities in which the etching and any releasing are completely suppressed. The "etch suppression" area is well defined by the illumination spot, which can be used to realize well-controlled heterogeneously etched regions on the same sample.

Costescu, Ruxandra M.

2011-10-01

33

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

34

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

International Nuclear Information System (INIS)

Highlights: ? Used surface imprinting technique with nano-TiO2 as sacrificial support material. ? Improved adsorption capability of the H-MIP1 compared with the previous work. ? Excellent mass transfer dynamics for the H-MIP1. ? Investigated adsorption thermodynamic of the H-MIP1. - Abstract: 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.

35

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

36

New class of layered materials  

International Nuclear Information System (INIS)

A new class of layered materials has been prepared by alternate deposition of two dissimilar metals. Strong experimental evidence is shown that coherent structures with layer thicknesses approaching interatomic spacing can be prepared in this fashion. The experimental x-ray measurements are found to be in good qualitative and quantitative agreement with model calculations

37

Fracture Spacing in Layered Materials  

Energy Technology Data Exchange (ETDEWEB)

We perform an elastostatic analysis of a periodic array of cracks under constant loading. We give an analytical solution and show that there is a limitation to the fracture spacing, due to a transition from an opening to a compressive loading. For this configuration, the threshold of the fracture spacing depends on neither the applied strain nor the elastic parameters of the material. This result shows that, in the general case of layered materials, the physical mechanism that is responsible for the limitation in the density of fractures is related mainly to the geometry of the problem. This is in agreement with observations and with recent numerical results.

Adda-Bedia, M.; Amar, M. Ben

2001-06-18

38

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

39

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

40

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

 
 
 
 
41

Thick photopolymer layers for holographic recording materials  

Digital Repository Infrastructure Vision for European Research (DRIVER)

In this article the behavior of thick photopolymer layers as material for holographic recording is studied. The material used is a photopolymer based on acrylamides, consisting of acrylamide as monomer, yellowish eosin as sensitizer and triethanolamine as radical generator, all on a matrix of polyvinyl alcohol. We studied the influence of the thickness of the layer on the behavior of the photopolymer as a holographic recording material. According to Kogelnik's theory, the thickness determines...

Garci?a Llopis, Celia; Fimia Gil, Antonio; Pascual Villalobos, Inmaculada

1999-01-01

42

Nano transfer and nanoreplication using deterministically grown sacrificial nanotemplates  

Science.gov (United States)

Methods, manufactures, machines and compositions are described for nanotransfer and nanoreplication using deterministically grown sacrificial nanotemplates. An apparatus, includes a substrate and a nanoconduit material coupled to a surface of the substrate. The substrate defines an aperture and the nanoconduit material defines a nanoconduit that is i) contiguous with the aperture and ii) aligned substantially non-parallel to a plane defined by the surface of the substrate.

Melechko, Anatoli V. (Oak Ridge, TN); McKnight, Timothy E. (Greenback, TN); Guillorn, Michael A. (Ithaca, NY); Ilic, Bojan (Ithaca, NY); Merkulov, Vladimir I. (Knoxville, TX); Doktycz, Mitchel J. (Knoxville, TN); Lowndes, Douglas H. (Knoxville, TN); Simpson, Michael L. (Knoxville, TN)

2012-03-27

43

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

44

Toughening elastomers with sacrificial bonds and watching them break.  

Science.gov (United States)

Elastomers are widely used because of their large-strain reversible deformability. Most unfilled elastomers suffer from a poor mechanical strength, which limits their use. Using sacrificial bonds, we show how brittle, unfilled elastomers can be strongly reinforced in stiffness and toughness (up to 4 megapascals and 9 kilojoules per square meter) by introducing a variable proportion of isotropically prestretched chains that can break and dissipate energy before the material fails. Chemoluminescent cross-linking molecules, which emit light as they break, map in real time where and when many of these internal bonds break ahead of a propagating crack. The simple methodology that we use to introduce sacrificial bonds, combined with the mapping of where bonds break, has the potential to stimulate the development of new classes of unfilled tough elastomers and better molecular models of the fracture of soft materials. PMID:24723609

Ducrot, Etienne; Chen, Yulan; Bulters, Markus; Sijbesma, Rint P; Creton, Costantino

2014-04-11

45

Bioinspired layered materials with superior mechanical performance.  

Science.gov (United States)

Nature has inspired researchers to construct structures with ordered layers as candidates for new materials with high mechanical performance. As a prominent example, nacre, also known as mother of pearl, consists of a combination of inorganic plates (aragonite calcium carbonate, 95% by volume) and organic macromolecules (elastic biopolymer, 5% by volume) and shows a unique combination of strength and toughness. Investigations of its structure reveal that the hexagonal platelets of calcium carbonate and the amorphous biopolymer are alternatively assembled into the orderly layered structure. The delicate interface between the calcium carbonate and the biopolymer is well defined. Both the building blocks that make up these assembled layers and the interfaces between the inorganic and organic components contribute to the excellent mechanical property of natural nacre. In this Account, we summarize recent research from our group and from others on the design of bioinspired materials composed by layering various primitive materials. We focus particular attention on nanoscale carbon materials. Using several examples, we describe how the use of different combinations of layered materials leads to particular properties. Flattened double-walled carbon nanotubes (FDWCNTs) covalently cross-linked in a thermoset three-dimensional (3D) network produced the materials with the highest strength. The stiffest layered materials were generated from borate orthoester covalent bonding between adjacent graphene oxide (GO) nanosheets, and the toughest layered materials were fabricated with Al2O3 platelets and chitosan via hydrogen bonding. These new building blocks, such as FDWCNTs and GO, and the replication of the elaborate micro-/nanoscale interface of natural nacre have provided many options for developing new high performance artificial materials. The interface designs for bioinspired layered materials are generally categorized into (1) hydrogen bonding, (2) ionic bonding, and (3) covalent bonding. Using these different strategies, we can tune the materials to have specific mechanical characteristics such as high strength, excellent strain resistance, or remarkable toughness. Among these design strategies, hydrogen bonding affords soft interfaces between the inorganic plates and the organic matrix. Covalent cross-linking forms chemical bonds between the inorganic plates and the organic matrix, leading to much stronger interfaces. The interfaces formed by ionic bonding are stronger than those formed by hydrogen bonding but weaker than those formed by covalent bonding. PMID:24635413

Cheng, Qunfeng; Jiang, Lei; Tang, Zhiyong

2014-04-15

46

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; Ostling, Mikael

2014-11-10

47

Electrically actuated sacrificial membranes for valving in microsystems  

Science.gov (United States)

Valving is essential to microflow circuits and networks in microsystem technology. Many different types of valves have been designed and fabricated. Membranes of sacrificial material have already been designed for one-shot valving. However, the new design proposed here, based on sacrificial micro-membranes with embedded electrodes, has the advantages of being efficient, easily controllable and requiring very low energy levels. We have shown that a 100 µm × 100 µm × 500 nm Si3N4 membrane with a platinum electrode can be actuated to break up with an energy input of only 6 µJ, during an actuation time of 200 µs. At rest, in the absence of actuation, such membranes can withstand a pressure of 1 bar. The goal of the development of such membranes is to hydrodynamically connect, one by one, a series of initially isolated micro-chambers implemented in a silicon chip.

Allain, M.; Berthier, J.; Basrour, S.; Pouteau, P.

2010-03-01

48

Porous ZnCo2O4 nanowires synthesis via sacrificial templates: high-performance anode materials of Li-ion batteries.  

Science.gov (United States)

A simple microemulsion-based method has been developed to synthesize ZnCo(2)(C(2)O(4))(3) nanowires that can be transformed to porous ZnCo(2)O(4) nanowires under annealing conditions. The morphology of porous ZnCo(2)O(4) nanowires can be tuned by the initial ZnCo(2)(C(2)O(4))(3) nanowires and the annealing temperatures. The as-synthesized porous ZnCo(2)O(4) nanowires have been applied as anode materials of Li-ion batteries, which show superior capacity and cycling performance. The porous one-dimensional (1D) nanostructures and large surface area are responsible for the superior performance. Moreover, it is indicated that porous ZnCo(2)O(4) nanowires synthesized at low annealing temperature (500 °C) show larger capacity and better cycling performance than that prepared at high annealing temperature (700 °C), because of their higher porosity and larger surface area. PMID:21395282

Du, Ning; Xu, Yanfang; Zhang, Hui; Yu, Jingxue; Zhai, Chuanxin; Yang, Deren

2011-04-18

49

Nanotransfer and nanoreplication using deterministically grown sacrificial nanotemplates  

Energy Technology Data Exchange (ETDEWEB)

Methods, manufactures, machines and compositions are described for nanotransfer and nanoreplication using deterministically grown sacrificial nanotemplates. A method includes depositing a catalyst particle on a surface of a substrate to define a deterministically located position; growing an aligned elongated nanostructure on the substrate, an end of the aligned elongated nanostructure coupled to the substrate at the deterministically located position; coating the aligned elongated nanostructure with a conduit material; removing a portion of the conduit material to expose the catalyst particle; removing the catalyst particle; and removing the elongated nanostructure to define a nanoconduit.

Melechko, Anatoli V. (Oak Ridge, TN); McKnight, Timothy E. (Greenback, TN), Guillorn, Michael A. (Ithaca, NY); Ilic, Bojan (Ithaca, NY); Merkulov, Vladimir I. (Knoxville, TN); Doktycz, Mitchel J. (Knoxville, TN); Lowndes, Douglas H. (Knoxville, TN); Simpson, Michael L. (Knoxville, TN)

2011-05-17

50

Atomic Layer Thermopile Materials: Physics and Application  

Directory of Open Access Journals (Sweden)

Full Text Available New types of thermoelectric materials characterized by highly anisotropic Fermi surfaces and thus anisotropic Seebeck coefficients are reviewed. Early studies revealed that there is an induced voltage in high TC oxide superconductors when the surface of the films is exposed to short light pulses. Subsequent investigations proved that the effect is due to anisotropic components of the Seebeck tensor, and the type of materials is referred to atomic layer thermopile (ALT. Our recent studies indicate that multilayer thin films at the nanoscale demonstrate enhanced ALT properties. This is in agreement with the prediction in seeking the larger figure of merit (ZT thermoelectric materials in nanostructures. The study of ALT materials provides both deep insight of anisotropic transport property of these materials and at the same time potential materials for applications, such as light detector and microcooler. By measuring the ALT properties under various perturbations, it is found that the information on anisotropic transport properties can be provided. The information sometimes is not easily obtained by other tools due to the nanoscale phase coexistence in these materials. Also, some remained open questions and future development in this research direction have been well discussed.

H.-U. Habermeier

2008-11-01

51

Radionuclide separations using pillared layered materials  

International Nuclear Information System (INIS)

This is the final report of a two-year Laboratory Directed Research and Development (LDRD) project at the Los Alamos National Laboratory (LANL). Pillared Layered Materials (PLMs) are layered inorganic ion exchangers propped apart by metal oxide pillars. PLMs have been synthesized to sorb strontium from liquid nuclear wastes. A study that compared over 60 sorbers for their ability to sorb strontium from Hanford simulants showed that PLMs were the best sorbers; strontium distribution coefficients (SrKd) > 20000 mL/g were obtained. In addition, PLMs showed a high degree of selectivity for strontium over cesium, transition metals, lanthanides and actinides. The sorption of strontium is, however, inhibited by complexants (EDTA); SrKd values drop to d values for Sr2+ and Ba2+ show a strong pH dependence; Kd values increase to >104 above pH 12. The general surface complexation mechanism explains the sorption of these cations on PLMs

52

Layered Atom Arrangements in Complex Materials  

Energy Technology Data Exchange (ETDEWEB)

In this report, we develop an atom layer stacking model to describe systematically the crystal structures of complex materials. To illustrate the concepts, we consider a sequence of oxide compounds in which the metal cations progress in oxidation state from monovalent (M{sup 1+}) to tetravalent (M{sup 4+}). We use concepts relating to geometric subdivisions of a triangular atom net to describe the layered atom patterns in these compounds (concepts originally proposed by Shuichi Iida). We demonstrate that as a function of increasing oxidation state (from M{sup 1+} to M{sup 4+}), the layer stacking motifs used to generate each successive structure (specifically, motifs along a 3 symmetry axis), progress through the following sequence: MMO, MO, M{sub r}O, MO{sub r/s}O{sub u/v}, MOO (where M and O represent fully dense triangular atom nets and r/s and u/v are fractions used to describe partially filled triangular atom nets). We also develop complete crystallographic descriptions for the compounds in our oxidation sequence using trigonal space group R{bar 3}.

K.E. Sikafus; R.W.Grimes; S.M.Corish; A.R. Cleave; M.Tang; C.R.Stanek; B.P. Uberuaga; J.A.Valdez

2005-04-15

53

Radionuclide separations using pillared layered materials  

Energy Technology Data Exchange (ETDEWEB)

This is the final report of a two-year Laboratory Directed Research and Development (LDRD) project at the Los Alamos National Laboratory (LANL). Pillared Layered Materials (PLMs) are layered inorganic ion exchangers propped apart by metal oxide pillars. PLMs have been synthesized to sorb strontium from liquid nuclear wastes. A study that compared over 60 sorbers for their ability to sorb strontium from Hanford simulants showed that PLMs were the best sorbers; strontium distribution coefficients ({sup Sr}K{sub d}) > 20000 mL/g were obtained. In addition, PLMs showed a high degree of selectivity for strontium over cesium, transition metals, lanthanides and actinides. The sorption of strontium is, however, inhibited by complexants (EDTA); {sup Sr}K{sub d} values drop to <20 mL/g when they are present. The most promising PLMs were the Cr, Ti, Zr, and Si pillared tantalum tungstate. The K{sub d} values for Sr{sup 2+} and Ba{sup 2+} show a strong pH dependence; K{sub d} values increase to >10{sup 4} above pH 12. The general surface complexation mechanism explains the sorption of these cations on PLMs.

Schroeder, N.C.; Wade, K.L.; Morgan, D.M. [and others

1998-12-31

54

Magnesium sacrificial anode behavior at elevated temperature  

International Nuclear Information System (INIS)

Magnesium sacrificial anode coupled to mild steel was tasted in sodium chloride and tap water environments at elevated temperatures. The anode failed to protect the mild steel specimens in tap water environment at all temperatures specified. This was partly due to low conductivity of this medium. The temperature factor did not help to activate the anode in this medium. In sodium chloride environment the anode demonstrated good protection for steel cathodes. The weight loss was high for magnesium in sodium chloride environment particularly beyond 60 degree centigrade. In tap water environment the weight loss was negligible for the anode. It also suffered localized shallow pitting corrosion. Magnesium anode cannot be utilized where high temperature is involved particularly in high conductivity mediums. Protection of structures containing high resistivity waters is not feasible using sacrificial anode system. (author)

55

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)

56

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

57

Contact mechanics for layered materials with randomly rough surfaces.  

Science.gov (United States)

The contact mechanics model of Persson is applied to layered materials. We calculate the M function, which relates the surface stress to the surface displacement, for a layered material, where the top layer (thickness d) has different elastic properties than the semi-infinite solid below. Numerical results for the contact area as a function of the magnification are presented for several cases. As an application, we calculate the fluid leak rate for laminated rubber seals. PMID:22301779

Persson, B N J

2012-03-01

58

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

59

Thermodynamics of sacrificial deoxidation of refractory metals  

International Nuclear Information System (INIS)

Sacrificial deoxidation via suboxide evaporation at high temperature and vacuum is one of the most important techniques for the purification of many refractory metals. A theoretical thermodynamic approach has been attempted to assess and examine the deoxidation tendencies of refractory metals of groups IV and V. Based on the thermodynamic data available for gaseous suboxides and reported or estimated values of oxygen activities in the metals, vapour pressures of suboxides have been calculated and plotted as a function of temperature and oxygen content of the metal. From these data it has been possible to estimate: (1) the extent of deoxidation, (2) the vaporization loss of metal during deoxidation, and (3) the rate of deoxidation. Calculations have also been made for ternary systems such as Nb-Zr-O and Ta-Hf-O. The calculated values are compared with the reported values based on the experimental observations. (author)

60

Measurement and modeling of terahertz spectral signatures from layered material  

Science.gov (United States)

Many materials such as drugs and explosives have characteristic spectral signatures in the terahertz (THz) band. These unique signatures hold great promise for potential detection utilizing THz radiation. While such spectral features are most easily observed in transmission,real life imaging systems will need to identify materials of interest from reflection measurements,often in non-ideal geometries. In this work we investigate the interference effects introduced by layered materials,whic h are commonly encountered in realistic sensing geometries. A model for reflection from a layer of material is presented,along with reflection measurements of single layers of sample material. Reflection measurements were made to compare the response of two materials; ?-lactose monohydrate which has sharp absorption features,and polyethylene which does not. Finally,the model is inverted numerically to extract material parameters from the measured data as well as simulated reflection responses from the explosive C4.

Kniffin, G. P.; Schecklman, S.,; Chen, J.; Henry, S. C.; Zurk, L. M.; Pejcinovic, B.; Timchenko, A. I.

2010-04-01

 
 
 
 
61

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

62

The mechanics of crack growth in layered materials  

Energy Technology Data Exchange (ETDEWEB)

Layered materials comprised of one brittle and one ductile constituent exhibit crack growth characteristics that depend on the sequential renucleation of cracks in each brittle layer. An analysis of the problem is presented with two different interface responses. One for a well-bonded, slipping interface and the other for an interface that debonds. It is shown that either slip or debonding enhance the fracture resistance, with debonding being the more effective. The analysis is compared with experimental results for several layered systems.

He, M.Y.; Heredia, F.E.; Wissuchek, D.J.; Shaw, M.C.; Evans, A.G. (Univ. of California, Santa Barbara, CA (United States). Materials Dept.)

1993-04-01

63

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

64

Layered zeolitic materials: an approach to designing versatile functional solids.  

Science.gov (United States)

Relevant layered zeolites have been considered in this perspective article from the point of view of the synthesis methodologies, materials characterization and catalytic implications, considering the unique physico-chemical characteristics of lamellar materials. The potential of layered zeolitic precursors to generate novel lamellar accessible zeolites through swelling, intercalation, pillarization, delamination and/or exfoliation treatments is studied, showing the chemical, functional and structural versatility exhibited by layered zeolites. Recent approaches based on the assembly of zeolitic nanosheets which act as inorganic structural units through the use of dual structural directing agents, the selective modification of germanosilicates and the direct generation of lamellar hybrid organic-inorganic aluminosilicates are also considered to obtain layered solids with well-defined functionalities. The catalytic applications of the layered zeolites are also highlighted, pointing out the high accessibility and reactivity of active sites present in the lamellar framework. PMID:24457617

Díaz, Urbano; Corma, Avelino

2014-07-21

65

The possibility of forming a sacrificial anode coating for Mg  

Energy Technology Data Exchange (ETDEWEB)

Mg is the most active engineering metal, and is often used as a sacrificial anode/coating to protect other engineering metals from corrosion attack. So far no sacrificial anode coating has been developed or considered for Mg. This study explores the possibility of forming a sacrificial coating for Mg. A lithiated carbon coating and a metaphosphated coating are applied on the Mg surface, respectively, and their open-circuit-potentials are measured in saturated Mg(OH)2 solution. They exhibit more negative potentials than bare Mg. SEM reveals that the metaphosphated coating offers more effective and uniform protection for Mg than the lithiated carbon coating. These preliminary results indicate that development of a sacrificial anode coating for Mg is indeed possible.

Dudney, Nancy J [ORNL; Li, Juchuan [Oak Ridge National Laboratory (ORNL); Sacci, Robert L [ORNL; Thomson, Jeffery K [ORNL

2014-01-01

66

Nanotransfer and nanoreplication using deterministically grown sacrificial nanotemplates  

Energy Technology Data Exchange (ETDEWEB)

Methods, manufactures, machines and compositions are described for nanotransfer and nanoreplication using deterministically grown sacrificial nanotemplates. An apparatus, includes a substrate and a nanoreplicant structure coupled to a surface of the substrate.

Melechko, Anatoli V. (Oak Ridge, TN); McKnight, Timothy E. (Greenback, TN); Guillorn, Michael A. (Ithaca, NY); Ilic, Bojan (Ithaca, NY); Merkulov, Vladimir I. (Knoxville, TN); Doktycz, Mitchel J. (Knoxville, TN); Lowndes, Douglas H. (Knoxville, TN); Simpson, Michael L. (Knoxville, TN)

2011-08-23

67

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

68

Epitaxially grown layered MFI-bulk MFI hybrid zeolitic materials.  

Science.gov (United States)

The synthesis of hybrid zeolitic materials with complex micropore-mesopore structures and morphologies is an expanding area of recent interest for a number of applications. Here we report a new type of hybrid zeolite material, composed of a layered zeolite material grown epitaxially on the surface of a bulk zeolite material. Specifically, layered (2-D) MFI sheets were grown on the surface of bulk MFI crystals of different sizes (300 nm and 10 ?m), thereby resulting in a hybrid material containing a unique morphology of interconnected micropores (?0.55 nm) and mesopores (?3 nm). The structure and morphology of this material, referred to as a "bulk MFI-layered MFI" (BMLM) material, was elucidated by a combination of XRD, TEM, HRTEM, SEM, TGA, and N(2) physisorption techniques. It is conclusively shown that epitaxial growth of the 2-D layered MFI sheets occurs in at least two principal crystallographic directions of the bulk MFI crystal and possibly in the third direction as well. The BMLM material combines the properties of bulk MFI (micropore network and mechanical support) and 2-D layered MFI (large surface roughness, external surface area, and mesoporosity). As an example of the uses of the BMLM material, it was incorporated into a polyimide and fabricated into a composite membrane with enhanced permeability for CO(2) and good CO(2)/CH(4) selectivity for gas separations. SEM-EDX imaging and composition analysis showed that the polyimide and the BMLM interpenetrate into each other, thereby forming a well-adhered polymer/particle microstructure, in contrast with the defective interfacial microstructure obtained using bare MFI particles. Analysis of the gas permeation data with the modified Maxwell model also allows the estimation of the effective volume of the BMLM particles, as well as the CO(2) and CH(4) gas permeabilities of the interpenetrated layer at the BMLM/polyimide interface. PMID:23045956

Kim, Wun-gwi; Zhang, Xueyi; Lee, Jong Suk; Tsapatsis, Michael; Nair, Sankar

2012-11-27

69

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

70

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

71

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 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

72

Sacrificial template method of fabricating a nanotube  

Energy Technology Data Exchange (ETDEWEB)

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 <001> 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

73

Shear zone refraction and deflection in layered granular materials.  

Science.gov (United States)

Refraction and deflection of shear zones in layered granular materials were studied experimentally and numerically. We show that (i) according to a recent theoretical prediction [T. Unger, Phys. Rev. Lett. 98, 018301 (2007)] shear zones refract in layered systems in analogy with light refraction, (ii) zone refraction obeys Snell's law known from geometric optics, and (iii) under natural pressure conditions (i.e., in the presence of gravity) the zone can also be deflected by the interface, so that the deformation of the high friction material is avoided. PMID:20365106

Börzsönyi, Tamás; Unger, Tamás; Szabó, Balázs

2009-12-01

74

Electromagnetic cloaking by layered structure of homogeneous isotropic materials.  

Science.gov (United States)

Electromagnetic invisibility cloak requires material with anisotropic distribution of the constitutive parameters as first proposed by Pendry et al. [Science 312, 1780 (2006)]. In this paper, we proposed an electromagnetic cloak structure that does not require metamaterials with subwavelength structured inclusions to realize the anisotropy or inhomogeneity of the material parameters. We constructed a concentric layered structure of alternating homogeneous isotropic materials that can be treated as an effective medium with the required radius-dependent anisotropy. 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 could be possibly realized by normal materials, therefore may lead to a practical path to an experimental demonstration of electromagnetic cloaking, especially in the optical range. PMID:19547468

Huang, Ying; Feng, Yijun; Jiang, Tian

2007-09-01

75

Capacitive micro force sensors manufactured with mineral sacrificial layers  

Digital Repository Infrastructure Vision for European Research (DRIVER)

In this work a prototype of micro force sensor of range ?N...mN is presented. Instead of the traditional piezoresistive strain sensing through thick-film resistors used for higher forces, a more effective principle is used: measurement of beam displacement rather than strain. A design of a cantilever sensor with capacitive electrodes, optionally coupled with an electrostatic force cancelling to achieve higher sensitivity, is proposed and discussed. The structuration of the device...

Fournier, Yannick; Wiedmer, Simon; Maeder, Thomas; Ryser, Peter

2007-01-01

76

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.)

77

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

78

Contact mechanics of layered elastic materials: experiment and theory  

Energy Technology Data Exchange (ETDEWEB)

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 {mu}m) layer of mica on a very thick layer of epoxy (>100 {mu}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' E{sub e}{sup *}, 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 surface energy, {gamma}{sub 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 F{sub p} according to F{sub p}/4{pi}R < {gamma}{sub sv} < F{sub p}/2{pi}R, and for this particular experiment was given as {gamma}{sub sv} = F{sub p}/3.5 {pi}R as compared with {gamma}{sub sv} = F{sub p}/3{pi}R for homogeneous materials.

McGuiggan, P M [Department of Materials Science and Engineering, Johns Hopkins University, Baltimore, MD 21218 (United States); Wallace, J S [MACS Consulting, Germantown, MD 20874 (United States); Smith, D T [Ceramics Division, National Institute of Standards and Technology, 100 Bureau Drive, Gaithersburg, MD 20899 (United States); Sridhar, I [School of Mechanical and Aerospace Engineering, Nanyang Technological University, 50 Nanyang Avenue, Singapore 639798, Singapore (Singapore); Zheng, Z W [School of Mechanical and Aerospace Engineering, Nanyang Technological University, 50 Nanyang Avenue, Singapore 639798, Singapore (Singapore); Johnson, K L [Engineering Department, University of Cambridge, Trumpington Street, Cambridge, England CB2 1PZ (United Kingdom)

2007-10-07

79

Candor Chasma - Massive (non-layered) material expos  

Science.gov (United States)

One of the most striking discoveries of the Mars Global Surveyor mission has been the identification of thousands of meters/feet of layers within the wall rock of the enormous martian canyon system, Valles Marineris.Valles Marineris was first observed in 1972 by the Mariner 9 spacecraft, from which the troughs get their name: Valles--valleys, Marineris--Mariner.Some hints of layering in both the canyon walls and within some deposits on the canyon floors were seen in Mariner 9 and Viking orbiter images from the 1970s. The Mars Orbiter Camera on board Mars Global Surveyor has been examining these layers at much higher resolution than was available previously.MOC images led to the realization that there are layers in the walls that go down to great depths. An example of the wall rock layers can be seen in MOC image 8403, shown above (C).MOC images also reveal amazing layered outcrops on the floors of some of the Valles Marineris canyons. Particularly noteworthy is MOC image 23304 (D, above), which shows extensive, horizontally-bedded layers exposed in buttes and mesas on the floor of western Candor Chasma. These layered rocks might be the same material as is exposed in the chasm walls (as in 8403--C, above), or they might be rocks that formed by deposition (from water, wind, and/or volcanism) long after Candor Chasma opened up.In addition to layered materials in the walls and on the floors of the Valles Marineris system, MOC images are helping to refine our classification of geologic features that occur within the canyons. For example, MOC image 25205 (E, above), shows the southern tip of a massive, tongue-shaped massif (a mountainous ridge) that was previously identified as a layered deposit. However, this MOC image does not show layering. The material has been sculpted by wind and mass-wasting--downslope movement of debris--but no obvious layers were exposed by these processes.Valles Marineris a fascinating region on Mars that holds much potential to reveal information about the early history and evolution of the red planet. The MOC Science Team is continuing to examine the wealth of new data and planning for new Valles Marineris targets once the Mapping Phase of the Mars Global Surveyor mission commences in March 1999.This image: Massive (non-layered) material exposed in central Candor Chasma. MOC image 25205 subframe shown at 11.7 meters (38.4 feet) per pixel resolution. Image shows the southern tip of a massive 'interior deposit' that points like a giant tongue from Ophir Chasma (to the north) down into the center of Candor Chasma. The ridged and grooved bright unit is the 'interior deposit'. South of this ridged unit is a low elevation surface mantled by dark dunes and sand. Image covers an area approximately 5.7 by 5.7 kilometers (3.5 x 3.5 miles). North is approximately up, illumination is from the lower right. Image 25205 was obtained during Mars Global Surveyor's 252nd orbit at 2:45 p.m. (PDT) on April 20, 1998.Malin Space Science Systems and the California Institute of Technology built the MOC using spare hardware from the Mars Observer mission. MSSS operates the camera from its facilities in San Diego, CA. The Jet Propulsion Laboratory's Mars Surveyor Operations Project operates the Mars Global Surveyor spacecraft with its industrial partner, Lockheed Martin Astronautics, from facilities in Pasadena, CA and Denver, CO.

1998-01-01

80

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

 
 
 
 
81

Estimation of stresses in layers of dentures’ relining materials  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Purpose: Durability tests of materials relining dentures should be carried out in conditions reflecting the realloading that accompanies bite force transmission. The influence of geometry resulting from a denture foundationshape on real stresses in relining has not been so far found.Design/methodology/approach: Using FEM modeling, identified were the stress levels in relining layers inconditions reflecting biting loading for two opposite cases of bone foundation atrophy.Findings: The equivale...

Z?mudzki, J.; Chladek, W.; Krukowska, J.

2008-01-01

82

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.

83

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

84

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

85

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

86

Investigations of sacrificial and plasma mirrors on the HELEN laser CPA beam  

Science.gov (United States)

The performance of sacrificial and plasma mirrors has been investigated on the HELEN laser chirped pulse amplification [CPA] beam line. Sacrificial mirrors are initially highly reflective surfaces that degrade during the course of a pulsed laser experiment. They are being considered for protecting the off axis parabolic surfaces used to focus CPA lasers from plasma physics target generated debris and shrapnel. Plasma mirrors are initially low reflectivity surfaces that transmit low intensity beams but produce a reflecting plasma surface during the course of the laser pulse. They are being investigated to prevent prepulse effects in plasma physics experiments and increase the contrast ratio of the incident laser beam.The sacrificial mirrors were operated at 45 degrees angle of incidence and an average input beam diameter of ~14 mm with intensities in the range 8 TW/cm2 to 44 TW/cm2. Dielectric protected silver and gold coatings as well as dielectric multi layers were studied as the mirror surfaces for directing all of the short pulse [500fs] laser beams onto tantalum foil targets of 10 microns thickness. Proton emissions from the foils monitored by radiochromic film were used to evaluate the beam irradiance achieved from the mirror surfaces. Glass witness plates were used to evaluate debris and shrapnel emissions from the mirror surfaces, the diagnostics and the target foils. The plasma mirrors were operated in a similar configuration but with beam diameters of ~8mm and irradiances of 57 TW/cm2 to 235 TW/cm2. Uncoated and sol gel anti-reflection coated fused silica were used as the high intensity mirror surfaces. The influence of surface coating on laser damage morphology will be described as well as post shot inspection of debris distributions.

Andrew, James E.; Comley, Andrew J.

2007-01-01

87

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

88

Studies of layered and pillared manganese oxide materials  

Science.gov (United States)

Synthetic Birnessite, an octahedral layered manganese oxide material called OL-1 was synthesized with Na+, K+, Na +/Mg2+, K+/Mg2+, Na +/K+ ions as interlayer cations by redox reactions between permanganate and alcohols in a strong basic media. Chromia pillared OL-1s were prepared under reflux conditions using trinuclear chromium hydroxyl acetate as a pillaring agent followed by calcination in a N2 atmosphere at 200°C. Vanadium oxide pillared OL-1s were obtained by intercalating neutral vanadyl acetylacetonate (VOacac) or vanadium acetylacetonate (Vacac) into the interlayer of OL-1 and subsequently calcining in air at 300°C. The synthesis procedures were monitored using X-ray diffraction studies. The resultant materials were characterized by XRD, X-ray absorption, X-ray photoelectron spectra, FTIR, UV-VIS, inductively coupled plasma, transmission electron spectroscopy, scanning electron microscopy with energy dispersive X-ray analysis, potentiometric titration, thermal analyses, TPD measurements, BET surface area and pore size distribution measurements. OL-1 materials prepared using this alcohol route showed enhanced thermal stabilities and increased Mg accommodation compared to OL-1s prepared with other methods. Based on the analysis methods developed here, Na-OL-1 exhibited recoverable and reversible structural and surface O2 oxygen species while K-OL-1 showed higher stability. Na-OL-1 had predominantly Bronsted acid sites resulting from OH groups bonded to Mn on Na-OL-1 surfaces, while the Na/Mg-OL-1 had mainly Lewis acid sites. Large porosity was obtained in chromia pillared OL-1 materials with a narrow pore size distribution centered around 18 A. Although these materials remained "amorphous" as determined by XRD after calcination, TEM morphology studies suggest that the materials were still layered. EXAFS studies indicated the formation of Cr-O-Mn bonds in the resultant materials via comer-shared linkages of CrO6 and MnO6 octahedra. Good crystallinity in VOacac intercalated OL-1 was achieved, which after calcination, led to the formation of mesoporous VOx pillared OL-1 materials with the pore diameters being in the range of 36 to 41 A. The intercalation of bulky neutral inorganic species into the interlayer of OL-1 through an exfoliation route simplified the pillaring process and preparative factors and made the process and pore sizes in the pillared materials controllable.

Ma, Ying

89

Thermal analysis of a double layer phase change material floor  

International Nuclear Information System (INIS)

Phase change materials (PCMs) can be used to shift the cooling or heating load from the peak period to the off-peak period. In this paper, a new double layer phase change material (PCM) floor is put forward. The two layers of PCM have different melting temperature. The system is used to store heat or cold energy in the off-peak period and release them in the peak period during heating or cooling. According to the numerical model built in this paper, the thermal performances of the floor are analyzed. The results show that the optimal melting temperatures of PCMs exist. The fluctuations of the floor surface temperatures and the heat fluxes will be reduced and the system still can provide a certain amount of heat or cold energy after the heat pump or chiller has been turned off for a long time. Compared to the floor without PCM, the energy released by the floor with PCM in peak period will be increased by 41.1% and 37.9% during heating and cooling when the heat of fusion of PCM is 150 kJ/kg. - Highlights: ? A new double layer phase change material floor is put forward. ? The system is used to store heat or cold energy in the off-peak period and release them in the peak period during heating or cooling. ? The optimal melting temperatures of PCMs in the system exist. ? The heat and cold energy released by the floor with PCM in peak period can be increased by 41.1% and 37.9%.

90

Nanoscale engineering materials by supercritical fluid and atomic layer deposition  

Science.gov (United States)

With the development of material science and technology, modification of substrates, which have random geometry and high aspect ratio three dimensional (3D) complex structures, with desired functional, reactive and stable coatings becomes important and challenging. The ability to fabricate mono- or multi-layers of functional materials with precisely controlled dimensions, finely tuned composition and molecular structures, attracts significant interests in materials science and is the key to construct such devices and structures at nano- and micro-scale with desired properties. In this study, supercritical carbon dioxide (scCO2) has been studied as an alternative route for modifying substrates due to the unique gas-like (low viscosity, high diffusivity and zero surface tension) and liquid-like properties (high density). (1) The reaction kinetics of metal oxides thin film deposition from pyrolysis of metal organics in scCO2 was studied in detail. This method was demonstrated as a powerful technique to coat oxides, including Al2O3, Ga2O3 and others, into 3D high aspect ratio complex structure of carbon nanotubes (CNTs) forest. (2) The low temperature scCO 2 based hydrogenolysis process was developed as a useful way to functionalize aligned CNTs forest with dense Nickel nanoparticles. On the second part of this work, atomic layer deposition (ALD)/molecular layer deposition (MLD), as a vapor phase, stepwise and self-limiting vacuum based deposition process, was demonstrated as a powerful way to form highly conformal and uniform film onto substrates, even into highly complex 3D complex structures. In this study, (4) Metal oxide ALD is applied onto 3D electrospun polymer microfiber mats template to illustrate an effective and robust strategy to fabricate long and uniform metal oxide microtubes with precisely controllable wall thickness. Designer tubes of various sizes and different materials were demonstrated by using this method. (5) By further extending this technique, complex coaxial Al2O3/ZnO/Al2O3 multilayed microtubular structure is fabricated, which provides an unique platform to study the solid state reaction and diffusion process (Kirkendall Effect) between Al2 O3 shells and the confined middle ZnO layers by annealing the samples at 700°C. (6) The extension of ALD-MLD process of polyamides, zinc hybrid, aminosilane self assembly monolayers were studied by various techniques to illustrate the surface reaction mechanism.

Peng, Qing

91

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

92

Encapsulation of the herbicide picloram by using polyelectrolyte biopolymers as layer-by-layer materials.  

Science.gov (United States)

Microcapsules of the herbicide picloram (PLR) were formulated by a layer-by-layer (LbL) self-assembly method using the polyelectrolyte biopolymers of biocompatible chitosan (CS) and the UV-absorbent sodium lignosulfonate (SL) as shell materials. The herbicide PLR was recrystallized and characterized using XRD analysis. The obtained PLR-loaded microcapsules were characterized by using SEM, FTIR, CLSM, and ?-potential measurements. The herbicide loading and encapsulation efficiency were also analyzed for the PLR-loaded microcapsules. The influence of LbL layer numbers on herbicide release and photodegradation rates was investigated in vitro. The results showed that the release rates and photodegradation rates of PLR in microcapsules decreased with increasing number of CS/SL self-assembly layers. The results demonstrated that polyelectrolyte biopolymer-based LbL multilayer microcapsules can be a promising approach for the controlled release of PLR as well as other pesticides with poor photostability or short half-release time. PMID:23544987

Wang, Xiaojing; Zhao, Jing

2013-04-24

93

Thermal transport in layered materials for thermoelectrics and thermal management  

Science.gov (United States)

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, respectively. Besides Bi2Te3 and graphene, many other materials in the family of layered materials also exhibit great promises for various applications in thermoelectrics, thermal management, and electronics. In order to investigate the thermal properties of general layered materials, we explore the use of tight-binding molecular dynamics (TBMD) approach, which neither relies on the availability of classical potentials nor demands significant computational resources as ab initio MD approach does. In addition, a general model for the effective phonon group velocities, which is relevant for the lattice thermal transport in general few-layer materials, is developed. First of all, two-body interatomic potentials in the Morse potential form have been developed for bismuth telluride. The density functional theory with local-density approximations is first used to calculate the total energies for many artificially distorted Bi2Te3 configurations to produce the energy surface. Then by fitting to this energy surface and other experimental data, the Morse potential form is parameterized. The fitted empirical interatomic potentials are shown to reproduce the elastic and phonon data well. With the classical interatomic potentials developed, molecular dynamics simulations are performed to predict the thermal conductivity of bulk Bi2Te3 at different temperatures, and the results agree with experimental data well. To facilitate phonon-engineering, we predict the thermal conductivity of Bi2Te3 nanowires with diameters ranging from 3 to 30 nm with both smooth and rough surfaces. It is found that when the nanowire diameter decreases to the molecular scale, the thermal conductivity shows significant reduction as compared to bulk value. On the other hand, the thermal conductivity for the 30-nm-diam nanowire only shows less than 20% reduction, in agreement with recent experimental data. Also, the thermal conductivity of nanowires shows a weaker temperature dependence than the typical T -1 trend, consistent with experimental observations. This is attributed to the strong boundary scattering of phonons. Being motivated by the recent experimental exfoliation of atomically-thin Bi2Te3 flakes, thermal conductivity of perfect and nanoporous few-quintuple Bi2Te3 thin films as well as nanoribbons with perfect and zig-zag edges is investigated using molecular dynamics (MD) simulations with Green-Kubo method. We find minimum thermal conductivity of perfect Bi2Te3 thin films with three quintuple layers (QLs) at room temperature. Nanoporous films and nanoribbons are studied for additional phonon scattering channels in suppressing thermal conductivity. So far we have studied the lattice thermal conductivity of Bi2Te 3 bulk and important nanostructures. To understand the detailed phonon transport, dominant phonon modes and how various nanostructures can efficiently alter the thermal conductivity in Bi2Te3 through phonon scattering, we further study the mode-wise phonon properties in Bi2Te 3 using spectral energy density approach (SED). The anharmonic phonon dispersions and relaxation times along ? - Z direction are extracted. To validate the as-obtained spectral properties, the lattice thermal conductivity in the cross-plane direction is obtained under isotropic approximation, which is found to agree with Green-Kubo predictions well. (Abstract shortened by UMI.).

Qui, Bo

94

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

95

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

96

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

97

Asymmetric wicking and reduced evaporation time of droplets penetrating a thin double-layered porous material  

Science.gov (United States)

We study numerically and experimentally the penetration and evaporation dynamics of droplets wicking into a thin double-layered porous material with order-of-magnitude difference in the physical properties between the layers. We show that such double-layered porous materials can be used to create highly asymmetrical wicking properties, preventing liquid droplets wicking from one surface to the other, while allowing wicking in the reverse direction. In addition, these double-layered porous materials are shown to reduce the evaporation time of droplets penetrating into the porous material, compared with a single-layered porous material of equal thickness and physical properties similar to either of the layers.

Gat, Amir D.; Vahdani, Aria; Navaz, Homayun; Nowakowski, Albert; Gharib, Morteza

2013-09-01

98

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

99

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

Directory of Open Access Journals (Sweden)

Full Text Available 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.

Sibele B. C. Pergher

1999-09-01

100

A novel electrode material for electric double-layer capacitors  

Science.gov (United States)

In this study, a novel electrode material, modified activated carbon aerogel, has been developed for electric double-layer capacitors (EDLCs). This novel material was produced by the activation of carbon aerogel under CO 2 flow, followed by surface modification with a surfactant, sodium oleate. It has been characterized by BET measurement and BJH method for its surface area and pore-size distribution, and by constant-current charge-discharge technique, cyclic voltammetry and electrochemical impedance spectrum (EIS) for its specific capacitance, equivalent series resistance and power capability. It was found that, after the surface modification, the wettability of the organic electrolyte based on non-polar organic solvent (i.e., propylene carbonate) to the activated carbon aerogel was improved greatly, which resulted in a lower internal resistance and a higher usable surface area. As results, a higher specific capacitance, energy density and power capability were achieved for the capacitor using the modified activated carbon aerogel electrodes than those without the surface modification. The effects from the surface modification became more significant at higher charge-discharge rates, at which the wettability of the electrolyte to the electrode material usually becomes more important and critical.

Wei, Y.-Z.; Fang, B.; Iwasa, S.; Kumagai, M.

 
 
 
 
101

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

102

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

103

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

Energy Technology Data Exchange (ETDEWEB)

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 (ZrO{sub 2}) 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 (UO{sub 2}, ZrO{sub 2}, FeO, SiO{sub 2}, Al{sub 2}O{sub 3}, CaO,..) which gives rise to a certain oxygen concentration in the metal melt. The thermochemical stability of ZrO{sub 2} 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 ZrO{sub 2}-FeO phases and therefore dissolution of ZrO{sub 2} 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 ZrO{sub 2} are sinteractive ramming mass, sintered ceramic bricks or ZrO{sub 2} 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.

Hellmann, S.; Funke, F.; Lansmann, V.; Friedrich, B. [Siemens AG, Power Generation (KWU), Erlangen (Germany)

2000-05-01

104

Formation of elongated fascicle-inspired 3D tissues consisting of high-density, aligned cells using sacrificial outer molding.  

Science.gov (United States)

The majority of muscles, nerves, and tendons are composed of fiber-like fascicle morphology. Each fascicle has a) elongated cells highly aligned with the length of the construct, b) a high volumetric cell density, and c) a high length-to-width ratio with a diameter small enough to facilitate perfusion. Fiber-like fascicles are important building blocks for forming tissues of various sizes and cross-sectional shapes, yet no effective technology is currently available for producing long and thin fascicle-like constructs with aligned, high-density cells. Here we present a method for molding cell-laden hydrogels that generate cylindrical tissue structures that are ~100 ?m in diameter with an extremely high length to diameter ratio (>100 : 1). Using this method we have successfully created skeletal muscle tissue with a high volumetric density (~50%) and perfect cell alignment along the axis. A new molding technique, sacrificial outer molding, allows us to i) create a long and thin cylindrical cavity of the desired size in a sacrificial mold that is solid at a low temperature, ii) release gelling agents from the sacrificial mold material after the cell-laden hydrogel is injected into fiber cavities, iii) generate a uniform axial tension between anchor points at both ends that promotes cell alignment and maturation, and iv) perfuse the tissue effectively by exposing it to media after melting the sacrificial outer mold at 37 °C. The effects of key parameters and conditions, including initial cavity diameter, axial tension, and concentrations of the hydrogel and gelling agent upon tissue compaction, volumetric cell density, and cell alignment are presented. PMID:24744046

Neal, Devin; Sakar, Mahmut Selman; Ong, Lee-Ling S; Harry Asada, H

2014-06-01

105

Integration of AlN with molybdenum electrodes and sacrificial amorphous silicon release using XeF2  

Science.gov (United States)

This paper presents a new post-CMOS-compatible integration scheme for AlN-based MEMS devices. The proposed scheme integrates molybdenum (Mo) bottom electrodes with an amorphous silicon (a-Si) sacrificial layer, which is etched using XeF2 to release the MEMS structures. This integration approach faces two potential issues, which are solved in this work: (i) poor adhesion of AlN with a-Si, and (ii) XeF2 attacking the Mo electrode during the removal of the a-Si sacrificial layer. The adhesion problem was solved by introducing a thin oxide layer between a-Si and AlN. The sidewalls of the Mo electrodes were protected by a 0.2 µm thick SiN spacer layer from the XeF2 attack. The robustness of the integration scheme was verified by fabricating an FBAR band pass filter. RF measurements on the FBAR band pass filter show that the proposed integration works well and can be utilized for other AlN-based MEMS devices in post-CMOS applications.

Sharma, Jaibir; Fernando, Sanchitha; Tan, Wee Ming

2014-03-01

106

Fabrication of sacrificial anode cathodic protection through casting method  

International Nuclear Information System (INIS)

Aluminum is one of the few metals that can be cast by all of the processes used in casting metals. These processes consist of die casting, permanent mold casting, sand casting (green sand and dry sand), plaster casting, investment casting, and continuous casting. Other processes such as lost foam, squeeze casting, and hot isostatic pressing are also used. Permanent mold casting method was selected in which used for fabricating of sacrificial anode cathodic protection. This product was ground for surface finished and fabricated in the cylindrical form and reinforced with carbon steel at a center of the anode. (Author)

107

Estimation of stresses in layers of dentures’ relining materials  

Directory of Open Access Journals (Sweden)

Full Text Available Purpose: Durability tests of materials relining dentures should be carried out in conditions reflecting the realloading that accompanies bite force transmission. The influence of geometry resulting from a denture foundationshape on real stresses in relining has not been so far found.Design/methodology/approach: Using FEM modeling, identified were the stress levels in relining layers inconditions reflecting biting loading for two opposite cases of bone foundation atrophy.Findings: The equivalent Huber-Mises` stresses have not reached their critical values, although tangentialstresses on the interfacial where relining is bonded with denture base have reached 440kPa, which, for some of thecommercial types of relining denotes the bonding strength.Research limitations/implications: The linear elastic mechanical characteristics were assumed. Hence,during further research, taken into account should be the “stiffening” of characteristics in the upper loadings range,which is typical for silicones.Practical implications: In case of a convex foundation the biggest danger will be caused by any bond defectsoccurring in the central area because in that area shear of bond has reached the highest values.Originality/value: Values of stresses components identified in this paper reflect the real shear conditions ofrelining bonding with denture base and might constitute a determinant for strength tests.

J. ?mudzki

2008-03-01

108

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

109

Reduction of saturation thickness for gamma radiation shielding materials using suitable front layer  

International Nuclear Information System (INIS)

In optimization of thickness of shielding materials when stratified layers of binary materials are used, the thickness and Z value of the front layer play significant roles. It has been found that a layer of high-Z material when placed before a gamma radiation shield reduces the optimum saturation thickness needed for shielding purpose. In the present investigation, measurements of energy albedo as well as optimum thickness for 662 keV energy photons have been reported using lead, tin and iron as front layer material and aluminium, concrete and iron as shielding materials. (author). 14 refs., 7 figs., 2 tabs

110

Photovoltaic properties of double layer devices consisting of titanium dioxide and porphyrin dispersed hole transporting material layer  

International Nuclear Information System (INIS)

The photovoltaic effect in the double layer device consisting of titanium dioxide (TiO2) and tetraphenyl-porphirin (TPP) blended with hole transporting material (HTM), denoted as ITO/TiO2/TPP+HTM/Au, has been investigated in this study. Short circuit photocurrent increases drastically by the usage of double-layered structure and fluorene based monomeric material as HTM. Photovoltaic properties are improved considerably using dopants and dyes with higher ionization potential energy than that of HTM. Furthermore, it was proposed that the quantum efficiency of the photovoltaic device is improved effectively by the treatment of ionic space charge polarization (poling) when supporting electrolyte was doped into organic layers. The enhancement of photocurrent in double layer device is explained in terms of the increase of electric field at the TiO2/organic layer interface due to the accumulation of ionic space charges

111

Standard test method for laboratory evaluation of magnesium sacrificial anode test specimens for underground applications  

CERN Document Server

1.1 This test method covers a laboratory procedure that measures the two fundamental performance properties of magnesium sacrificial anode test specimens operating in a saturated calcium sulfate, saturated magnesium hydroxide environment. The two fundamental properties are electrode (oxidation potential) and ampere hours (Ah) obtained per unit mass of specimen consumed. Magnesium anodes installed underground are usually surrounded by a backfill material that typically consists of 75 % gypsum (CaSO4·2H2O), 20 % bentonite clay, and 5 % sodium sulfate (Na2SO4). The calcium sulfate, magnesium hydroxide test electrolyte simulates the long term environment around an anode installed in the gypsum-bentonite-sodium sulfate backfill. 1.2 This test method is intended to be used for quality assurance by anode manufacturers or anode users. However, long term field performance properties may not be identical to property measurements obtained using this laboratory test. Note 1—Refer to Terminology G 15 for terms used ...

American Society for Testing and Materials. Philadelphia

1997-01-01

112

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

Scientific Electronic Library Online (English)

Full Text Available SciELO Brazil | Language: Spanish Abstract in spanish [...] Abstract in english 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 an [...] d applications of the products.

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

113

Teo-iconología del poder sacrificial entre los mochica Teo-iconology of sacrificial power among the Moche  

Directory of Open Access Journals (Sweden)

Full Text Available Partiendo de las evidencias icónicas del rasgo predatorio y sus equivalentes narrativos presentes en diferentes piezas de la cultura mochica, el texto busca establecer (i una metodología de aproximación al sacrificio caníbal que tenga en cuenta diversas formas icónicas de ‹escritura›, y (ii una explicación so-ciocósmica de la política sacrificial. Al articular lo escritural y lo político, es posible aportar una nueva perspectiva a la rica discusión que sobre las relaciones entre canibalismo y poder han venido proponiendo los arqueólogos, los semióticos y los antropólogos de las culturas prehispánicas.Based on the iconographic evidences of predation and their narrative equivalents, present in different aspects of the Mochica culture, this essay seeks to establish (i a methodology for approaching the cannibal sacrifice taking into account different forms of iconic ‹writing›; and (ii establish a socio-cosmic explanation to sacrificial politics. By articulating these scriptural and political aspects, the paper will provide a new perspective to the rich discussion on the relationship between cannibalism and power that has been proposed by archaeologists, anthropologists and studies on the semiotic of Prehispanic cultures.

Adolfo Chaparro Amaya

2011-12-01

114

Teo-iconología del poder sacrificial entre los mochica / Teo-iconology of sacrificial power among the Moche  

Scientific Electronic Library Online (English)

Full Text Available SciELO Chile | Language: Spanish Abstract in spanish Partiendo de las evidencias icónicas del rasgo predatorio y sus equivalentes narrativos presentes en diferentes piezas de la cultura mochica, el texto busca establecer (i) una metodología de aproximación al sacrificio caníbal que tenga en cuenta diversas formas icónicas de ‹escritura›, y (ii) una ex [...] plicación so-ciocósmica de la política sacrificial. Al articular lo escritural y lo político, es posible aportar una nueva perspectiva a la rica discusión que sobre las relaciones entre canibalismo y poder han venido proponiendo los arqueólogos, los semióticos y los antropólogos de las culturas prehispánicas. Abstract in english Based on the iconographic evidences of predation and their narrative equivalents, present in different aspects of the Mochica culture, this essay seeks to establish (i) a methodology for approaching the cannibal sacrifice taking into account different forms of iconic ‹writing›; and (ii) establish a [...] socio-cosmic explanation to sacrificial politics. By articulating these scriptural and political aspects, the paper will provide a new perspective to the rich discussion on the relationship between cannibalism and power that has been proposed by archaeologists, anthropologists and studies on the semiotic of Prehispanic cultures.

Adolfo, Chaparro Amaya.

2011-12-01

115

Thin nickel silicide layer formation on silicon on insulator material  

Energy Technology Data Exchange (ETDEWEB)

In this work we study the phase transition of 14 and 7 nm thin Ni layers grown on standard silicon and silicon on insulator (SOI) wafers implanted with As. We investigate the thermal stability of the NiSi phase using spike thermal processes which are widely used to preserve shallow junction from dopant diffusion during electrical activation. Nickel reaction has been performed in nitrogen ambient in the temperature range from 450 to 1125 deg. C and has been characterised by electrical and structural analyses. In spite of the thin layers used, spike annealing processes extend the stability window up to 900 deg. C preserving the NiSi layer from structural degradation. Moreover, the use of SOI substrates has a favourable impact on the silicide structure that prevents agglomeration and hole formation.

Alberti, A. [CNR-IMM Sezione Catania, Stradale Primosole 50, 95121 Catania (Italy)]. E-mail: alessandra.alberti@imm.cnr.it; Cafra, B. [CNR-IMM Sezione Catania, Stradale Primosole 50, 95121 Catania (Italy); Bongiorno, C. [CNR-IMM Sezione Catania, Stradale Primosole 50, 95121 Catania (Italy); Mannino, G. [CNR-IMM Sezione Catania, Stradale Primosole 50, 95121 Catania (Italy); Privitera, V. [CNR-IMM Sezione Catania, Stradale Primosole 50, 95121 Catania (Italy); Kammler, T. [AMD Saxony LLC and Co. KG, Wilschdorfer Landstrasse 101, Dresden (Germany); Feudel, T. [AMD Saxony LLC and Co. KG, Wilschdorfer Landstrasse 101, Dresden (Germany)

2004-12-15

116

Thin nickel silicide layer formation on silicon on insulator material  

International Nuclear Information System (INIS)

In this work we study the phase transition of 14 and 7 nm thin Ni layers grown on standard silicon and silicon on insulator (SOI) wafers implanted with As. We investigate the thermal stability of the NiSi phase using spike thermal processes which are widely used to preserve shallow junction from dopant diffusion during electrical activation. Nickel reaction has been performed in nitrogen ambient in the temperature range from 450 to 1125 deg. C and has been characterised by electrical and structural analyses. In spite of the thin layers used, spike annealing processes extend the stability window up to 900 deg. C preserving the NiSi layer from structural degradation. Moreover, the use of SOI substrates has a favourable impact on the silicide structure that prevents agglomeration and hole formation

117

Noise and vibration level reduction by covering metal structures with layers of damping materials. [considering viscoelastic insulation layers  

Science.gov (United States)

One of the most important methods of reducing the noise and vibration level is the damping of the secondary sources, such as metal plates, often used in vehicle structures, by means of covering materials with high internal viscosity. Damping layers are chosen at an optimum thickness corresponding to the frequency and temperature range in which a certain structure works. The structure's response corresponding to various real situations is analyzed by means of a measuring chain including electroacoustical or electromechanical transducers. The experimental results provide the dependence of the loss factor and damping transmission coefficient as a function of the damping layer thickness or of the frequency for various viscoelastic covering materials.

Rugina, I.; Paven, H. T. O.

1974-01-01

118

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

119

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

120

Fully three-dimensional microfabrication with a grayscale polymeric self-sacrificial structure  

Science.gov (United States)

We present in this paper a novel method to fabricate fully three-dimensional (3D) microstructures and moving parts using a partially crosslinked polymer as sacrificial supports. This is realized on a projection microstereolithography (PµSL) which produces both the microstructure and the sacrificial part simultaneously using digital grayscale images. To establish the selectivity of the etchant to the partially crosslinked sacrificial parts, we measured the etching rate as a function of photo-crosslinking light intensity and the light exposure time. This technology may enable more complex scaffolds in tissue engineering and smart hydrogel devices.

Xia, Chunguang; Fang, Nicholas

2009-11-01

 
 
 
 
121

Abradable layer for a flow machine, comprises a particle composite material and a composite that contains ceramic particles with surface functional layers  

DEFF Research Database (Denmark)

A machine abradable layer (10), comprises a particle composite material, and a composite (1) that contains ceramic particles (2) with functional layers on the surface (20). The layers form stable intermediary phases at high operating temperatures. The intermediary phases are partly formed by a chemical reaction between a precursor and the ceramic particles. The material is used as an abradable layer for a machine, eg a gas turbine, turbo compressor etc. The layer can operate at high temperatures.

Wilson, Scott unknown

122

Tribological and Wear Properties of Multi-Layered Materials  

Digital Repository Infrastructure Vision for European Research (DRIVER)

The usage of fabrics as reinforcements in composites is spreading due to fabrics’ properties. The use of fabrics allows obtaining of sinuous surfaces, for instance, unlike the use of prepregs. Using fabrics as reinforcements it is also possible to obtain laminate-like materials having the same matrix in all their volume. In the case of pre-pregs usage always it is necessary to discuss about the bonding between individual plies. For this study eight materials were formed. The forming method ...

Bria, V.; Dima, D.; Andrei, G.; -g Birsan, I.; Circiumaru, A.

2011-01-01

123

Tribological and Wear Properties of Multi-Layered Materials  

Directory of Open Access Journals (Sweden)

Full Text Available The usage of fabrics as reinforcements in composites is spreading due to fabrics’ properties. The use of fabrics allows obtaining of sinuous surfaces, for instance, unlike the use of prepregs. Using fabrics as reinforcements it is also possible to obtain laminate-like materials having the same matrix in all their volume. In the case of pre-pregs usage always it is necessary to discuss about the bonding between individual plies. For this study eight materials were formed. The forming method consisted in placing the pre-polymer imbued fabric pieces into a mould to obtain plates of composites. Two types of fabric were used: one simple type of untwisted tows of carbon fibres and the second one simple type of alternated untwisted tows of carbon and aramide fibres. Both fabrics were prepared in order to ensure the matrix adherence. The polymer matrix is realised from epoxy system EPIPHEN RE 4020 / EPIPHEN DE 4020 filled with clay and talc in equal amounts of 5% (weight ratio. The use of clay and talc were meant to improve the thermal dimensional stability of final materials. Tribological properties of formed materials were studied using pin-on-disk method with steel disk and pins made of materials. Both orientation of reinforcement fibres relative to friction direction were taken into account. Results are encouraging further studies in order to identify the best solution of forming a multi-component material with more than one designable property.

V. Bria

2011-09-01

124

Surface layer properties of the workpiece material in high performance grinding  

Directory of Open Access Journals (Sweden)

Full Text Available 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 layer, as well as the burned surfaces and microcracks phenomena were investigated. The conducted experimental investigations allow the surface layer properties of the workpiece material in high performance grinding to be defined.

M. Gostimirovi?

2012-01-01

125

Engineering interconnected 3D vascular networks in hydrogels using molded sodium alginate lattice as the sacrificial template.  

Science.gov (United States)

Engineering 3D perfusable vascular networks in vitro and reproducing the physiological environment of blood vessels is very challenging for tissue engineering and investigation of blood vessel function. Here, we engineer interconnected 3D microfluidic vascular networks in hydrogels using molded sodium alginate lattice as sacrificial templates. The sacrificial templates are rapidly replicated in polydimethylsiloxane (PDMS) microfluidic chips via Ca(2+)-crosslinking and then fully encapsulated in hydrogels. Interconnected channels with well controlled size and morphology are obtained by dissolving the monolayer or multilayer templates with EDTA solution. The human umbilical vein endothelial cells (HUVECs) are cultured on the channel linings and proliferated to form vascular lumens. The strong cell adhesion capability and adaptive response to shear stress demonstrate the excellent cytocompatibility of both the template and template-sacrificing process. Furthermore, the barrier function of the endothelial layer is characterized and the results show that a confluent endothelial monolayer is fully developed. Taken together, we develop a facile and rapid approach to engineer a vascular model that could be potentially used in physiological studies of vascular functions and vascular tissue engineering. PMID:24887141

Wang, Xue-Ying; Jin, Zi-He; Gan, Bo-Wen; Lv, Song-Wei; Xie, Min; Huang, Wei-Hua

2014-08-01

126

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)

127

Wide-gap layered oxychalcogenide semiconductors: Materials, electronic structures and optoelectronic properties  

International Nuclear Information System (INIS)

Applying the concept of materials design for transparent conductive oxides to layered oxychalcogenides, several p-type and n-type layered oxychalcogenides were proposed as wide-gap semiconductors and their basic optical and electrical properties were examined. The layered oxychalcogenides are composed of ionic oxide layers and covalent chalcogenide layers, which bring wide-gap and conductive properties to these materials, respectively. The electronic structures of the materials were examined by normal/inverse photoemission spectroscopy and energy band calculations. The results of the examinations suggested that these materials possess unique features more than simple wide-gap semiconductors. Namely, the layered oxychalcogenides are considered to be extremely thin quantum wells composed of the oxide and chalcogenide layers or 2D chalcogenide crystals/molecules embedded in an oxide matrix. Observation of step-like absorption edges, large band gap energy and large exciton binding energy demonstrated these features originating from 2D density of states and quantum size effects in these layered materials

128

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

129

Layer separation for material discrimination cargo imaging system  

Science.gov (United States)

We propose an approach to boost the accuracy of the performance of a high-energy x-ray material discrimination imaging system. The theory of using two energies of x-rays to scan objects to extract the atomic information has been well developed. Such an approach is known as dual-energy imaging. At the beginning of this century, mega-volt-level dual-energy systems began to be applied to extract information regarding the materials inside a cargo container. For a system that scans at two x-ray energies, the ratio between the attenuations of the two energies will be different for different materials. Using this property, we can classify the content of a cargo container from the attenuation ratio image. However, thick shielding can reduce the signal-to-noise ratio such that correct material identification with low false alarm rate is unfeasible without further image processing. We have developed a method for high atomic number discrimination that can more accurately identify a region of high atomic number. The pixels of each object are clustered using our proposed clustering approach. The thickness and ratio of high- and low-energy attenuations of each object can then be more correctly calculated by separating it from its background. Our method can significantly improve the accuracy by suppressing false alarms and increasing the detection rate.

Fu, Kenneth; Ranta, Dale; Das, Pankaj; Guest, Clark

2010-01-01

130

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 washing process.

131

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

132

Lattice dynamics of a layered material BC 2N  

Science.gov (United States)

Vibrational properties of new layered compounds BC 2N are investigated based on a generalized valence-force field model whose force constants have been determined from ab initio total energy calculation. The calculated phonon density-of-states spectra in the higher-energy region show different peak structures depending on local atomic arrangements. If crystal structures of BC 2N have patterns segregated into graphite and hexagonal boron nitride and each segregated domain contains more than dozens of atoms, the phonon spectra of these structures can be described by a superposition of the spectra of graphite and hexagonal boron nitride. There is a possibility of determining polymorphic structures of BC 2N from the lattice vibrations.

Nozaki, Hanae; Itho, Satoshi

1996-02-01

133

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

134

Advanced Materials and Detection Methods in Ultrathin-Layer Chromatography  

Science.gov (United States)

The performance of highly anisotropic, nanostructured, thin-film ultrathin-layer chromatography (UTLC) media with porosity and architecture engineered using the glancing-angle deposition (GLAD) process is investigated. Anisotropic structures resembling nanoblades are fabricated on the plates, producing channel-like features that partially decouple analyte migration from development direction, and offering new separation behaviours. These GLAD UTLC plates provide channel features that reduce transverse spot broadening while providing the wide pores required for rapid migration and high separation performance with plate numbers approaching 800. The rapid separations typical of these miniaturized plates call for new alternative detection techniques. I have designed, implemented and characterized a measurement system which records UTLC separations in full colour with 32 µm spatial resolution and 33 ms temporal resolution. My code analyzes multiple tracks per plate, filters analyte spots by colour, and automatically generates time-resolved figures of merit. Both absorption and transmission detection modes are examined, each of which offers their own advantages.

Oko, Anthony James

135

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

136

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

International Nuclear Information System (INIS)

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 (O2TRs) 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 layematerials to be reduced. Once the ALD layer was 40 nm thick, WVTRs and O2TRs 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.

137

Generation of spectral holes by inserting central structurally chiral layer defects in periodic structurally chiral materials  

Science.gov (United States)

The insertion of a structurally chiral layer defect between two identical chiral mirrors, made of periodic structurally chiral materials such as chiral liquid crystals and chiral sculptured thin films, generates two different types of spectral holes, depending on the thicknesses of the chiral mirrors and the central layer defect.

Lakhtakia, Akhlesh

2007-07-01

138

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

International Nuclear Information System (INIS)

emonstrated 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

139

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)

140

Silk as a biocohesive sacrificial binder in the fabrication of hydroxyapatite load bearing scaffolds.  

Science.gov (United States)

Limitations of current clinical methods for bone repair continue to fuel the demand for a high strength, bioactive bone replacement material. Recent attempts to produce porous scaffolds for bone regeneration have been limited by the intrinsic weakness associated with high porosity materials. In this study, ceramic scaffold fabrication techniques for potential use in load-bearing bone repairs have been developed using naturally derived silk from Bombyx mori. Silk was first employed for ceramic grain consolidation during green body formation, and later as a sacrificial polymer to impart porosity during sintering. These techniques allowed preparation of hydroxyapatite (HA) scaffolds that exhibited a wide range of mechanical and porosity profiles, with some displaying unusually high compressive strength up to 152.4 ± 9.1 MPa. Results showed that the scaffolds exhibited a wide range of compressive strengths and moduli (8.7 ± 2.7 MPa to 152.4 ± 9.1 MPa and 0.3 ± 0.1 GPa to 8.6 ± 0.3 GPa) with total porosities of up to 62.9 ± 2.7% depending on the parameters used for fabrication. Moreover, HA-silk scaffolds could be molded into large, complex shapes, and further machined post-sinter to generate specific three-dimensional geometries. Scaffolds supported bone marrow-derived mesenchymal stem cell attachment and proliferation, with no signs of cytotoxicity. Therefore, silk-fabricated HA scaffolds show promise for load bearing bone repair and regeneration needs. PMID:24881027

McNamara, Stephanie L; Rnjak-Kovacina, Jelena; Schmidt, Daniel F; Lo, Tim J; Kaplan, David L

2014-08-01

 
 
 
 
141

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

142

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

143

Improving impact resistance of ceramic materials by energy absorbing surface layers  

Science.gov (United States)

Energy absorbing surface layers were used to improve the impact resistance of silicon nitride and silicon carbide ceramics. Low elastic modulus materials were used. In some cases, the low elastic modulus was achieved using materials that form localized microcracks as a result of thermal expansion anisotropy, thermal expansion differences between phases, or phase transformations. In other cases, semi-vitreous or vitreous materials were used. Substantial improvements in impact resistance were observed at room and elevated temperatures.

Kirchner, H. P.; Seretsky, J.

1974-01-01

144

Liquid phase exfoliation of 2D layered materials and their application  

Science.gov (United States)

In this work, several materials possessing a layered structure were investigated using a technique of exfoliation in liquid phase to produce few- to mono-layers of the material. Materials exfoliated in such a way included graphite, boron nitride, molybdenum disulfide and tungsten disulfide. Subsequent transmission electron microscopy and accompanying electron diffraction patterns revealed that few and mono layer forms of these materials have been realized through this exfoliation method. Ultraviolet-visible spectroscopy confirmed the shifting of the band gaps in molybdenum and tungsten disulfides that is predicted in reducing the number of layers of these materials and was also used to confirm the band gap of the boron nitride. As a potential application, exfoliated molybdenum disulfide was used in the construction of electrodes for electrical charge storage in an electrochemical double layer capacitor, or supercapacitor, style device. Cyclic voltammetry, galvanostatic charge discharge, and electrochemical impedance spectroscopy measurements were performed using three different electrolytes, which showed good capacitive behavior for these devices. Using the data from electrochemical impedance spectroscopy, equivalent circuit models were generated to represent the systems in different electrolytes. From this, it was determined that the capacitive behavior of these systems was partially diffusion limited.

Winchester, Andrew J.

145

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

146

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

147

Magnetic orientation and control of magnetic anisotropy in thermoelectric and superconducting materials with layered crystal structures  

International Nuclear Information System (INIS)

We report magnetic orientation of layered functional materials, thermoelectric and superconducting compounds, with feeble magnetic susceptibility using three different magnetic orientation techniques and control of their magnetic anisotropies. For thermoelectric layered oxides, the combination of magnetic orientation and electrophoretic deposition enabled the fabrication of multi-layered thermoelectric modules containing a highly oriented thermoelectric layer formed by the static field. For superconducting compounds, tri-axial orientation of RF-based high critical temperature superconductors with and without twin microstructure using a modulated rotation magnetic field was attempted, and their magnetization axes at room temperature were determined. Moreover, we now focus on the magnetic orientation of Iron-based pnictide superconductors in epoxy resin, and these magnetic orientation techniques are useful for the fabrication of functional materials with high performance and for the clarification of mechanism of superconductivity in Iron-based pnictides. (author)

148

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

149

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

150

Different materials as a cathode modification layer on the impact of organic solar cells  

Science.gov (United States)

Organic thin film solar cells based on conjugated polymer or small molecules have showed an interesting approach to energy conversion since Tang reported a single donor-accepter hetero-junction solar cell. The power conversion efficiency of organic solar cells has increased steadily over last decade. Small-molecular weight organic double heterojunction donor-acceptor layer organic solar cells (OSC) with a structure of indium-tin-oxide (ITO)/CuPc(200Å)/C60(400Å)/x/Ag(1000Å), using CuPc(copper Phthalocyanine)as donor layer, and Alq3(8-Hydroxyquinoline aluminum salt), BCP(Bromocresol purple sodium salt) and Bphen(4'7-diphyenyl-1,10-phenanthroline) as cathode modification layer, respectively were fabricated. The performance of OSC was studied as a function of the different materials as an cathode modification layer to optimize the structure. The current-voltage characteristic of the solar cell under AM1.5 solar illumination at an intensity of 100 mw/cm2 showed that the power conversion efficiency (PCE) was dependent of the different materials of the cathode modification layer. the efficiency along with the different materials as an cathode modification layer will diminish under that standard solar illumination(AM1.5)was obtained. Using a double heterostructure of ITO/CuPc(200Å)/C60(400Å)/Alq3(60Å)/Ag(1000Å) with high-vacuum evaporation technology, the efficiency was 0.587%.the efficiency was 0.967% when the material of the cathode modification layer was BCP, with the structure of ITO/CuPc(200Å)/C60(400Å)/BCP(35Å)/Ag(1000Å), and the efficiency was 0.742% when the material of the cathode modification layer was Bphen, with the structure of ITO/CuPc(200Å)/C60(400Å)/ Bphen(50Å)/Ag(1000Å).Using different materials as a cathode modification layer, it can be seen that the material which matches the energy level could even eventually be able to improve the energy conversion efficiency more.

Zhong, Jian; Huang, Qiuyan; Yu, Junsheng; Jiang, Yadong

2010-10-01

151

Process for forming one or more substantially pure layers in substrate material using ion implantation  

Energy Technology Data Exchange (ETDEWEB)

The method comprises selecting an implantable element and a substrate material to be implanted which, at the implant/anneal temperatures, have limited mutual solubility and have no intermediate phases formed. In an example, Be is implanted with 11 {times}10{sup 17} Al/cm{sup 2} at 200 keV and then annealed for 1 h at 500 C. Rutherford backscattering shows that layer formation occurred during the anneal. SEM shows rectangular Be defects in the Al layer. Other examples of implantable elements and suitable substrate materials are tabulated. 6 figs, 1 table. (DLC)

Musket, R.G.; Brown, D.W.; Munir, Z.A.

1990-12-31

152

Disrupting admicelle formation and preventing surfactant adsorption on metal oxide surfaces using sacrificial polyelectrolytes.  

Science.gov (United States)

The adsorption of anionic, cationic, and nonionic surfactants was measured on high-surface area silica and alumina nanoparticles when in the presence of the proposed polyelectrolyte sacrificial agents. Surfactant adsorption was characterized using two types of adsorption isotherms: one with constant polymer concentration and varying surfactant concentration, and another with a varying polymer concentration and constant surfactant concentration. Polystyrenesulfonate and Polydiallyl dimethylammonium chloride were tested as potential sacrificial agents on alumina and silica, respectively. Each surfactant/polymer system was allowed to reach equilibrium and supernatant surfactant concentrations were measured. This information was then plotted in order to determine what, if any, effect the proposed sacrificial agent had on the equilibrium adsorption. Results indicate that both of these polymers can have a large effect on total surfactant adsorption at a variety of surfactant concentrations. PMID:24826944

Weston, Javen S; Harwell, Jeffrey H; Shiau, Benjamin J; Kabir, Mahfuz

2014-06-10

153

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

154

Anodic dissolution of Al sacrificial anodes in NaCl solution containing Ce  

Energy Technology Data Exchange (ETDEWEB)

Research highlights: {yields} Ce improves the current efficiency of Al sacrificial anodes. {yields} Ce enhances a uniform attack on the surface of the Al alloy. {yields} The dissolution of the Al anode in chloride media initiates at precipitations where Ce is enriched. {yields} Ce enhances the activation on the surface of Al sacrificial anodes. - Abstract: The corrosion behaviour of Al-Zn-In sacrificial anodes has been investigated in a sodium chloride solution containing CeCl{sub 3}. Scanning electron microscopy, energy-dispersive X-ray analysis, and inductively coupled plasma mass spectrometry have been employed to gain knowledge of the micro-morphology and corrosion process of the Al alloy. Cerium, both as the alloy element and as the additive in the NaCl solution, improves the electrochemical properties of the Al-Zn-In alloy. The activation of Ce in the Al-Zn-In alloy in the NaCl solution has been studied.

Xiong, W. [Hubei Key Laboratory of Materials Chemistry and Service, School of Chemistry and Chemical Engineering, Huazhong University of Science and Technology, Wuhan 430074 (China); Qi, G.T., E-mail: qigongtai@mail.hust.edu.c [Hubei Key Laboratory of Materials Chemistry and Service, School of Chemistry and Chemical Engineering, Huazhong University of Science and Technology, Wuhan 430074 (China); Guo, X.P. [Hubei Key Laboratory of Materials Chemistry and Service, School of Chemistry and Chemical Engineering, Huazhong University of Science and Technology, Wuhan 430074 (China); Lu, Z.L. [Analytical and Testing Center, Huazhong University of Science and Technology, Wuhan 430074 (China)

2011-04-15

155

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

156

Simulation of trapping properties of high ? material as the charge storage layer for flash memory application  

International Nuclear Information System (INIS)

We investigated the trapping properties of high ? material as the charge storage layer in non-volatile flash memory devices using a two-dimensional device simulator, Medici. The high ? material is sandwiched between two silicon oxide layers, resulting in the Silicon-Oxide-High ?-Oxide-Silicon (SOHOS) structure. The trap energy levels of the bulk electron traps in high ? material were determined. The programming and erasing voltage and time using Fowler Nordheim tunneling were estimated by simulation. The effect of deep level traps on erasing was investigated. Also, the effect of bulk traps density, thickness of block oxide and thickness of high ? material on the threshold voltage of the device was simulated

157

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)

158

Multi-layered Poly-Dimethylsiloxane As A Non-Hermetic Packaging Material For Medical MEMS  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Poly-dimethylsiloxane (PDMS) is an attractive material for packaging implantable biomedical microdevices owing to its biocompatibility, ease in application, and bio-friendly mechanical properties. Unfortunately, devices encapsulated by PDMS lack the longevity for use in chronic implant applications due to defect-related moisture penetration through the packaging layer. This paper describes an effort to improve the performance of PDMS as packaging material by constructing the encapsulant from ...

Lachhman, S.; Zorman, C. A.; Ko, W. H.

2012-01-01

159

Monte Carlo program for the transport of ?-particles through layers of different materials  

International Nuclear Information System (INIS)

The transport of electrons through a homogeneous material has been treated by various authors. At Julich, a Monte Carlo package has been developed to cover the electron transport through layers of different materials. The main program follows the path of the electron and keeps book of its energy deposition. The program allows both the calculation for plane and point sources and a plane or finitely extended receptor

160

Film of lignocellulosic carbon material for self-supporting electrodes in electric double-layer capacitors  

Digital Repository Infrastructure Vision for European Research (DRIVER)

A novel thin, wood-based carbon material with heterogeneous pores, film of lignocellulosic carbon material (FLCM), was successfully fabricated by carbonizing softwood samples of Picea jezoensis (Jezo spruce). Simultaneous increase in the specific surface area of FLCM and its affinity for electrolyte solvents in an electric double-layer capacitor (EDLC) were achieved by the vacuum ultraviolet/ozone (VUV/O3) treatment. This treatment increased the specific surface area of FLCM by 50% over that ...

Tsubasa Funabashi; Jun Mizuno; Masamichi Sato; Masao Kitajima; Makoto Matsuura; Shuichi Shoji

2013-01-01

 
 
 
 
161

Metal and semiconductor nanoparticles stabilized in ultrathin nanofilms and layer-structured materials  

Science.gov (United States)

The interlamellar space of layer structured materials, such as montmorillonite, kaolinite, graphite oxide can be regarded as a nanophase reactor, in which size-quantized semiconductor and noble metal particles can be prepared. Particle growth is sterically hindered in the interlamellar space between neighboring lamellae which favors the formation of 2-10 nm particles. These synthesis strategies were successfully applied for the preparation and incorporation of Pd and Ag metal and CdS, ZnO, SnO2 semiconductor nanoparticles. Layer-by-layer self-assembled nanofilms were prepared from aqueous suspensions of semiconductor nanoparticles and various clay mineral suspensions onto glass surface. The nanoparticles adsorb on the surface of the support wiht their protecting layers allwoing the preparation of semiconductor and noble metal nanocomposites by this method. The properties of these nanocomposites have been investigated by optical measurements, x-ray diffraction, small angle x-ray scattering, atomic force and transmission electron microscopy.

Dekany, Imre; Szabo, Tamas; Korosi, Laszlo

2003-04-01

162

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

163

Film of lignocellulosic carbon material for self-supporting electrodes in electric double-layer capacitors  

Directory of Open Access Journals (Sweden)

Full Text Available A novel thin, wood-based carbon material with heterogeneous pores, film of lignocellulosic carbon material (FLCM, was successfully fabricated by carbonizing softwood samples of Picea jezoensis (Jezo spruce. Simultaneous increase in the specific surface area of FLCM and its affinity for electrolyte solvents in an electric double-layer capacitor (EDLC were achieved by the vacuum ultraviolet/ozone (VUV/O3 treatment. This treatment increased the specific surface area of FLCM by 50% over that of original FLCM. The results obtained in this study confirmed that FLCM is an appropriate self-supporting EDLC electrode material without any warps and cracks.

Tsubasa Funabashi

2013-09-01

164

Embedded proteins and sacrificial bonds provide the strong adhesive properties of gastroliths  

Science.gov (United States)

The adhesive properties of gastroliths from a freshwater crayfish (Cherax quadricarinatus) were quantified by colloidal probe atomic force microscopy (AFM) between heavily demineralized gastrolith microparticles and gastrolith substrates of different composition. Combined AFM and transmission electron microscopy studies demonstrated that the sequential detachment and large adhesion energies that characterise the adhesive behaviour of a native gastrolith substrate are dominated by sacrificial bonds between chitin fibres and between chitin fibres and CaCO3. The sacrificial bonds were shown to be strongly related to the gastrolith proteins and when the majority of these proteins were removed by ethylenediaminetetraacetic acid (EDTA), the sequential detachment disappeared and the adhesive energy was reduced by more than two orders of magnitude.The adhesive properties of gastroliths from a freshwater crayfish (Cherax quadricarinatus) were quantified by colloidal probe atomic force microscopy (AFM) between heavily demineralized gastrolith microparticles and gastrolith substrates of different composition. Combined AFM and transmission electron microscopy studies demonstrated that the sequential detachment and large adhesion energies that characterise the adhesive behaviour of a native gastrolith substrate are dominated by sacrificial bonds between chitin fibres and between chitin fibres and CaCO3. The sacrificial bonds were shown to be strongly related to the gastrolith proteins and when the majority of these proteins were removed by ethylenediaminetetraacetic acid (EDTA), the sequential detachment disappeared and the adhesive energy was reduced by more than two orders of magnitude. Electronic supplementary information (ESI) available. See DOI: 10.1039/c2nr30536d

Thormann, Esben; MizunoPresent Address: Nihon L'Oreal, Research; Innovation Center, 3-2-1 Sakado, Takatsu, Kawasaki, Kanagawa, Japan., Hiroyasu; Jansson, Kjell; Hedin, Niklas; Fernández, M. Soledad; Arias, José Luis; Rutland, Mark W.; PaiPresent Address: CenterFunctional Nanomaterials, Brookhaven National Laboratory, 735 Brookhaven Avenue, Upton, New York 11973., Ranjith Krishna; Bergström, Lennart

2012-06-01

165

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

Energy Technology Data Exchange (ETDEWEB)

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.

Hirvikorpi, Terhi, E-mail: terhi.hirvikorpi@vtt.f [VTT Technical Research Centre of Finland, Biologinkuja 7, Espoo, P.O. Box 1000, FI-02044 VTT (Finland); Vaehae-Nissi, Mika, E-mail: mika.vaha-nissi@vtt.f [VTT Technical Research Centre of Finland, Biologinkuja 7, Espoo, P.O. Box 1000, FI-02044 VTT (Finland); Harlin, Ali, E-mail: ali.harlin@vtt.f [VTT Technical Research Centre of Finland, Biologinkuja 7, Espoo, P.O. Box 1000, FI-02044 VTT (Finland); Karppinen, Maarit, E-mail: maarit.karppinen@tkk.f [Laboratory of Inorganic Chemistry, Department of Chemistry, Aalto University School of Science and Technology, Kemistintie 1, P.O. Box 16100, FI-00076 AALTO (Finland)

2010-07-30

166

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.

167

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

168

The Influnece of Peat Layer on Hidrogen and Aluminium Concentration Originating from the Substratum Sulphidic Materials  

Directory of Open Access Journals (Sweden)

Full Text Available Much of peatland in Indonesia has sulphidic materials as substratum. Soil acidity and metal elements in peatland may originate from the sulphidic materials which occur underneath of the peat layer. Peat soil buffering capacity and chelating ability of the peat materials regulate the soil acidity and metal solubility in the peatland. The study was aimed to examine the influence of peat thickness and land hydrological conditions on the concentrations of exchangeable aluminium (Al and hidrogen (H in the peatland. The study was carried out on peaty acid sulphate soil, deep peat, moderate peat and shallow peat. Exchangeable Al and H were observed in the wet season, transition from wet to dry season and dry season. The results showed that exchangeables of Al and H were mainly originated from sulphidic material which were occured underneath of the peat layer. Peat layer had an important role on the solubility of Al and H in the peatland. Peat thickness had influence on exchangeable-Al and H, 50 cm of the peat thickness (shallow peat was the critical for peat function to reduce the Al and H solubility in the peatland. Hydrological condition factor did not influence on the solubility of Al and H.

Benito Heru Purwanto

2012-09-01

169

Hierarchical hybrid organic-inorganic materials with tunable textural properties obtained using zeolitic-layered precursor.  

Science.gov (United States)

Novel layered zeolitic organic-inorganic materials have been synthesized using a two-dimensional zeolite precursor IPC-1P prepared by a top-down approach from zeolite UTL. The formation of porous materials containing organic linkers or polyhedral oligomeric siloxane covalently bonded to zeolite layers in the interlayer space was confirmed by a variety of characterization techniques (N2/Ar sorption analysis, XRD, (29)Si and (13)C NMR, TEM). The organic-inorganic porous hybrids obtained by intercalation with silsesquioxane posessed layered morphology and contained large crystalline domains. The hybrids exhibited mesoporous or hierarchical micro-/mesoporous systems, stable up to 350 °C. Textural properties of the formed zeolitic organic-inorganic materials can be controlled by varying the linker or synthetic conditions over a broad range. Surface areas and pore volumes of synthesized hybrids significantly exceed those for parent zeolite UTL and corresponding swollen material; the amount of micropores increased with increasing rigidity and size of the organic linker in the order biphenyl > phenylene > ethanediyl. PMID:24451039

Opanasenko, Maksym; Parker, Wallace O'Neil; Shamzhy, Mariya; Montanari, Erica; Bellettato, Michela; Mazur, Michal; Millini, Roberto; ?ejka, Ji?í

2014-02-12

170

Method of manufacturing test pieces formed with oxide layers containing radioactive materials  

International Nuclear Information System (INIS)

Purpose: To obtain test pieces having oxide layers with the same natures as oxide layers containing radioactive materials formed in high temperature and high pressure water of a nuclear reactor and also containing radioactive materials of necessary concentrations and types. Method: A solution is prepared by previously adding a predetermined amount of a solution of radioactive chloride and a solution of not-radioactive chloride of the same element to an aqueous boric acid solution controlled to a certain concentration. Then, the solution is passed through boric type anionic exchange resins to obtain a solution of radioactive boric acid salt at a required concentration not containing chlorine at all. The solution and metal pieces are put into an autoclave and, after removing the oxygen in the autoclave by nitrogen gas bubbling, heated at a required temperature for a certain period of time. Accordingly, a test specimen having oxide layers of the same natures as those containing radioactive materials formed in high temperature and high pressure water in the nuclear reactor and containing radioactive materials of required concentrations and types can be obtained. (Yoshihara, H.)

171

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

Science.gov (United States)

Layered materials of graphene and MoS?, 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-MoS?-graphene and graphene-MoS?-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. PMID:24162001

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

2013-12-01

172

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

173

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

174

Efficient perfect matched layer for hybrid MRTD-FDTD computation with lossy dielectric material boundaries  

Science.gov (United States)

Existing implementation of perfectly matched layers (PML) constraining the computational volume in an electromagnetic modeling of open structures has been shown to be efficient. However, cases with absorbing materials inserted into PML require substantial amount of memory and calculation time spent on the computation of the field inside the PML layer. In this paper we are addressing these problems by introducing a new computational method. As the procedure requires some substantial amount of memory and operations to compute fields in the PML layer, the paper addresses these issues. The PML split-field equations are revisited yielding a reduction from four-term storage to only three. In addition, the new algorithm is used with a new hybrid MRTD-FDTD (HMRTD) method applied to various lossy structures, conjointly with a higher-order field evaluation. Results demonstrate the efficiency of the new PML algorithm as compared to current schemes.

Massy, I.; Peña, N.; Ney, M. M.

2012-01-01

175

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

176

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

177

Triple-Layer Rewritable Disc with Sb-Based Phase-Change Material  

Science.gov (United States)

We have been developing a triple-layer rewritable disc on the base of Blu-ray disc systems using a Mn-Sb-Te-Ge phase-change material and N/2 write strategy. The remarkable features of the Mn-Sb-Te-Ge phase-change material are the high crystallization speed and high thermal stability of amorphous marks. The N/2 write strategy can be set at a long cooling pulse period and can realize the formation of amorphous marks of sufficient size. As a result, a sufficient symbol error rate (SER) and a high read stability were achieved and we confirmed the feasibility of a triple-layer rewritable disc with 100 Gbyte and 72 Mbps recording rate.

Shingai, Hiroshi; Kato, Tatsuya; Kosuda, Masanori; Takagi, Yasuhiro; Oyake, Hisaji; Hirata, Hideki

2010-08-01

178

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

179

Effect of complex alloying of powder materials on properties of laser melted surface layers  

International Nuclear Information System (INIS)

Quality and properties of laser melted surface layers produced using self-fluxing powder mixture of Ni-Cr-B-Si system and the same powders with enhanced Fe content alloyed with Co, Ti, Nb, Mo have been investigated. Composition of powder material is determined which does not cause of defect formation under laser melting and makes possible to produce a good mechanical and tribological properties of treated surface

180

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

 
 
 
 
181

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

182

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

Energy Technology Data Exchange (ETDEWEB)

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., E-mail: tokitani.masayuki@LHD.nifs.ac.jp [National Institute for Fusion Science, Oroshi, Toki, Gifu 509-5292 (Japan); Masuzaki, S. [National Institute for Fusion Science, Oroshi, Toki, Gifu 509-5292 (Japan); Yoshida, N. [Research Institute for Applied Mechanics, Kyushu University, Kasuga-Koen, Kasuga, Fukuoka 816-8580 (Japan); Sagara, A.; Noda, N.; Yamada, H. [National Institute for Fusion Science, Oroshi, Toki, Gifu 509-5292 (Japan)

2013-07-15

183

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

184

Tin disulfide-an emerging layered metal dichalcogenide semiconductor: materials properties and device characteristics.  

Science.gov (United States)

Layered metal dichalcogenides have attracted significant interest as a family of single- and few-layer materials that show new physics and are of interest for device applications. Here, we report a comprehensive characterization of the properties of tin disulfide (SnS2), an emerging semiconducting metal dichalcogenide, down to the monolayer limit. Using flakes exfoliated from layered bulk crystals, we establish the characteristics of single- and few-layer SnS2 in optical and atomic force microscopy, Raman spectroscopy and transmission electron microscopy. Band structure measurements in conjunction with ab initio calculations and photoluminescence spectroscopy show that SnS2 is an indirect bandgap semiconductor over the entire thickness range from bulk to single-layer. Field effect transport in SnS2 supported by SiO2/Si suggests predominant scattering by centers at the support interface. Ultrathin transistors show on-off current ratios >10(6), as well as carrier mobilities up to 230 cm(2)/(V s), minimal hysteresis, and near-ideal subthreshold swing for devices screened by a high-k (deionized water) top gate. SnS2 transistors are efficient photodetectors but, similar to other metal dichalcogenides, show a relatively slow response to pulsed irradiation, likely due to adsorbate-induced long-lived extrinsic trap states. PMID:25247490

Huang, Yuan; Sutter, Eli; Sadowski, Jerzy T; Cotlet, Mircea; Monti, Oliver L A; Racke, David A; Neupane, Mahesh R; Wickramaratne, Darshana; Lake, Roger K; Parkinson, Bruce A; Sutter, Peter

2014-10-28

185

Single-material zinc sulfide bi-layer antireflection coatings for GaAs solar cells.  

Science.gov (United States)

We demonstrated the efficiency improvement of GaAs single-junction (SJ) solar cells with the single-material zinc sulfide (ZnS) bi-layer based on the porous/dense film structure, which was fabricated by the glancing angle deposition (GLAD) method, as an antireflection (AR) coating layer. The porous ZnS film with a low refractive index was formed at a high incident vapor flux angle of 80° in the GLAD. Each optimum thickness of ZnS bi-layer was determined by achieving the lowest solar weighted reflectance (SWR) using a rigorous coupled-wave analysis method in the wavelength region of 350-900 nm, extracting the thicknesses of 20 and 50 nm for dense and porous films, respectively. The ZnS bi-layer with a low SWR of ~5.8% considerably increased the short circuit current density (J(sc)) of the GaAs SJ solar cell to 25.57 mA/cm(2), which leads to a larger conversion efficiency (?) of 20.61% compared to the conventional one without AR layer (i.e., SWR~31%, J(sc) = 18.81 mA/cm(2), and ? = 14.82%). Furthermore, after the encapsulation, its J(sc) and ? values were slightly increased to 25.67 mA/cm(2) and 20.71%, respectively. For the fabricated solar cells, angle-dependent reflectance properties and external quantum efficiency were also studied. PMID:24104577

Leem, Jung Woo; Jun, Dong-Hwan; Heo, Jonggon; Park, Won-Kyu; Park, Jin-Hong; Cho, Woo Jin; Kim, Do Eok; Yu, Jae Su

2013-09-01

186

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

187

Structural factors affecting lithium transport in lithium-excess layered cathode materials  

Science.gov (United States)

Lithium ion batteries have drawn significant attention as the principle energy storage device powering today's mobile electronic equipment. Despite the increased usage, the performance of current lithium ion battery technology falls short of the requirements needed for large format applications such as electric vehicles. The layered lithium-excess oxide compounds Li[NixLi1/3-2x/3Mn2/3-x/3]O2 are of interest as a new generation of cathode materials for high energy density lithium ion batteries. Efforts to achieve a better understanding of the electrochemistry of lithium-excess materials require the connection of crystal structure to electrochemical properties. In this dissertation, a combination of advanced characterization techniques was used as a tool to understand the intercalation mechanism of the layered lithium-excess transition metal oxide Li[NixLi1/3-2x/3Mn 2/3-x/3]O2. The research identified that synthesis influences the structure of the material specifically the surface of the particles. The formation of a hydroxide rich surface film decreases the electrochemical performance. Post synthesis modifications including high pressure and high temperature leads to the formation of a second layered phase in the bulk; however, the treated samples display good electrochemical properties. This result underlines the flexibility of the structure of Li[NixLi1/3-2x/3Mn 2/3-x/3]O2, a feature uncommon to other layered transition metal oxides. Surface characterization of the layered lithium-excess cathodes following electrochemical cycling revealed the formation of a new surface phase 1 to 5 nm thick as well as insight to the complex cation rearrangement process and phase transformation. This part of the research identified that significant changes occurred during electrochemical cycling; however did not identify when the transformations occurred. Investigation using in situ techniques during the first electrochemical cycle shows that the structure undergoes irreversible changes in lattice parameters and microstrain. Microstrain analysis shows that the material undergoes large increases in microstrain during the voltage plateau region. During the charging cycle, charge compensation mechanisms such as oxygen removal and cation migration accommodates the microstrain; however during discharge, these compensation mechanisms do not exist; therefore, causing the microstrain to increase. The analysis of structural changes before, during and following electrochemical property testing has led to an increased understanding of the lithium transport mechanisms in the lithium-excess series of materials.

Fell, Christopher R.

188

Sacrificial Tamper Slows Down Sample Explosion in FLASH Diffraction Experiments  

International Nuclear Information System (INIS)

Intense and ultrashort x-ray pulses from free-electron lasers open up the possibility for near-atomic resolution imaging without the need for crystallization. Such experiments require high photon fluences and pulses shorter than the time to destroy the sample. We describe results with a new femtosecond pump-probe diffraction technique employing coherent 0.1 keV x rays from the FLASH soft x-ray free-electron laser. We show that the lifetime of a nanostructured sample can be extended to several picoseconds by a tamper layer to dampen and quench the sample explosion, making <1 nm resolution imaging feasible.

189

Surface acoustic admittance and absorption of highly porous, layered, fibrous materials  

Science.gov (United States)

Some acoustic properties of Kevlar-29 - a fine fibered, layered material is investigated. Kevlar is characterized by very high strength, uniform filaments arranged in a parallel batt where most filaments are random in the x-y plane but ordered as planes in the z direction. For experimental purposes, volume porosity, static flow resistance and mean filament diameter are used to identify the material. To determine the acoustic surface admittance of Kevlar, batts of the material are cut into small pads and placed into a standing wave tube terminated by a rigid brass plug. The attenuation and relative phase shift are recorded at each frequency in the range of 50 to 6000 Hz. Normalized conductance and susceptance are combined to form the acoustic absorption coefficient. The data are compared with theory by plotting the normalized admittance and normal incident absorption coefficient versus cyclic frequency.

Tesar, J. S.; Lambert, R. F.

1984-01-01

190

Preparation of thin layer materials with macroporous microstructure for SOFC applications  

International Nuclear Information System (INIS)

A facile and versatile method using polymethyl methacrylate (PMMA) microspheres as pore formers has been developed to prepare thin layer oxide materials with controlled macroporous microstructure. Several mixed oxides with fluorite and perovskite-type structures, i.e. doped zirconia, ceria, ferrites, manganites, and NiO-YSZ composites have been prepared and characterised by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), nitrogen adsorption and mercury porosimetry. The synthesised materials are nanocrystalline and present a homogeneous pore distribution and relatively high specific surface area, which makes them interesting for SOFC and catalysis applications in the intermediate temperature range. - Graphical abstract: Thin films materials of mixed oxides with potential application in SOFC devices have been prepared with macroporous microstructure using PMMA microspheres as pore formers. Display Omitted

191

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

192

Layered single-metal hydroxide/ethylene glycol as a new class of hybrid material.  

Science.gov (United States)

Neutral ethylene glycol (EG) molecules have been intercalated into zinc hydroxide layers to produce a new hybrid material in which only one kind of metal ion is included. Initially, layered basic zinc acetate (LBZA, Zn(5)(OH)(8)(CH(3)COO)(2).2H(2)O) was prepared from a methanolic zinc acetate dihydrate solution. The immersion of LBZA in EG resulted in its intercalation, which was accompanied by an interlayer expansion of 7.12 A, as revealed by X-ray diffractometry. A Fourier transform infrared spectroscopic study indicated that the new compound contained both the acetate groups and the EG molecules. Together with thermogravimetry-differential thermal analysis, a composition of the new compound was estimated to be Zn(5)(OH)(8)(CH(3)COO)(2)(HOC(2)H(4)OH)(2).2H(2)O. The EG intercalation was found to increase the dehydration temperature of the zinc hydroxide layers from 130 to 180 degrees C. So the thermally stable material is then promising as a new class of precursors in creating organic-inorganic nanocomposites. PMID:16390083

Kasai, Asayo; Fujihara, Shinobu

2006-01-01

193

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

194

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

195

Thermal properties measurement of dry bulk materials with a cylindrical three layers device  

Science.gov (United States)

This paper presents a new method dedicated to thermal properties (conductivity and diffusivity) measurement of dry bulk materials including powders. The cylindrical three layers experimental device (brass/bulk material/stainless steel) and the principle of the measurement method based on a crenel thermal excitation are presented. The one-dimensional modeling of the system is used for a sensitivity analysis and to calculate the standard deviation of the estimation error. Experimental measurements are carried out on three bulk materials: glass beads, cork granules, and expanded polystyrene beads. The estimated thermal properties are compared with the values obtained by other measurement methods. Results are in good agreement with theoretical predictions: both thermal conductivity and diffusivity can be estimated with a good accuracy for low density material like cork granules or expanded polystyrene beads since only thermal diffusivity can be estimated for heavier materials like glass beads. It is finally shown that this method like all transient methods is not suited to the thermal characterization of wet bulk materials.

Jannot, Y.; Degiovanni, A.

2013-09-01

196

CDR 1 shielding mortar and the filling of sacrificial shields of Alto Lazio nuclear power station  

International Nuclear Information System (INIS)

The use of mortars for shelding needs in place of heavy concrete or metals was growing in the last fifteen years. The reason is they are easy to use in applications where the shilding or the technological requirement are severe or construction field asks for peculiar devices. Mortar emploied in the filling of the central part of the Alto Lazio 1 and 2 Sacrificial Shields was studied and produced by Nuclear Protection, with the continuous surveillance by ENEL, CCN, and ENEA. The qualification required a long sequence of analyses and experimental tests. In the report are indicated the characteristics of the CDR 1 mortar, with the technical and the QC requirements, the technological tests, the neutron and gamma attenuation tests and the thermogravimetric tests performed; the filling of a 1:1 scale moke-up, and finally the filling of the two A.L. sacrificial shields

197

Embedded proteins and sacrificial bonds provide the strong adhesive properties of gastroliths  

DEFF Research Database (Denmark)

The adhesive properties of gastroliths from a freshwater crayfish (Cherax quadricarinatus) were quantified by colloidal probe atomic force microscopy (AFM) between heavily demineralized gastrolith microparticles and gastrolith substrates of different composition. Combined AFM and transmission electron microscopy studies demonstrated that the sequential detachment and large adhesion energies that characterise the adhesive behaviour of a native gastrolith substrate are dominated by sacrificial bonds between chitin fibres and between chitin fibres and CaCO3. The sacrificial bonds were shown to be strongly related to the gastrolith proteins and when the majority of these proteins were removed by ethylenediaminetetraacetic acid (EDTA), the sequential detachment disappeared and the adhesive energy was reduced by more than two orders of magnitude. © 2012 The Royal Society of Chemistry.

Thormann, Esben; Mizuno, Hiroyasu

2012-01-01

198

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

199

Electrothermal crack analysis in a finite conductive layer with temperature-dependent material properties  

Energy Technology Data Exchange (ETDEWEB)

The method of Greenwood and Williamson is extended to obtain a solution to the coupled non-linear problem of steady-state electrical and thermal conduction across a crack in a conductive layer, for which the electrical resistivity and thermal conductivity are functions of temperature. The problem can be decomposed into the solution of a pair of non-linear algebraic equations involving boundary values and material properties. The new mixed-boundary value problem given from the thermal and electrical boundary conditions for the crack in the conductive layer is reduced in order to solve a singular integral equation of the first kind, the solution of which can be expressed in terms of the product of a series of the Chebyshev polynomials and their weight function. The non-existence of the solution for an infinite conductor in electrical and thermal conduction is shown. Numerical results are given showing the temperature field around the crack.

Jang, Yong Hoon; Lee, Sang Young [Yonsei University, Seoul (Korea, Republic of)

2006-08-15

200

Modification of the structure and surface layer properties of hard magnetic materials with plasma processing  

International Nuclear Information System (INIS)

Processing of hard magnetic materials like Nd-Fe-B and Sm-Co with pulsed plasma streams gives the possibility to modify its physical and chemical properties considerably. In particular, in combination with deposition of protective coatings, the corrosion resistance can be essentially improved. Due to specific processes initiated by plasma treatment, such as fast heating and melting of surface layer with simultaneous penetration of ions of plasma streams to the material depth and following high-speed cooling (cooling rate ?10-6 K/c), effective modification of surface layer has been achieved. Features of pulsed plasma stream interaction with surface of the samples have been discussed. Controlled crystallization of amorphous alloys allows creation of new materials for producing permanent magnets. For this purpose it is important to form specific multiphase microstructure of alloy from the amorphous state. X-ray amorphous Nd2Fe23B3 phase has been synthesized as a result of the interaction of accelerated helium plasma streams with Nd8Fe87B5 alloy. Microstructure and composition of modified surface layer are examined. It is shown that integral content of elements have not been changed actually after plasma treatment. However distribution of constituent elements in the modified layer is not homogenous. Atoms in modified layer are redistributed diffusively due to the formation of domains (?50 nm) that are centers of crystallization of Nd2Fe23B3 phase. Nd atoms push off to the domains borders and form individual inclusions. Features of crystallization and formation of magnetic phases have been studied, optimal annealing conditions (temperature and time) have been determined. Optimal alloy composition with highest magnetic characteristics has been defined. Thermal stability tests of magnetic flux have been carried out also. Influence of deposited SiO2 protective coatings on corrosion resistance of hard-magnetic alloys has been studied. The tests were carried out by gravimetric method in the environment of distill water vapors of 100% humidity at room temperature. It was observed that uncoated samples after 48 hours testing had the trails of point corrosion and an average gain in weight was 0.120%. While deep red-brown encrustation are quickly developed on unprotected samples and substantial increase in weight after 120 hours of exposure is found, the coated samples show the first visual developments of corrosion only after 744 hours and the weigh gain did not exceed 0.02 % on average. Investigations of protective Ti coatings deposited with ECR plasma source have been performed also. Coating modification and mixing under the pulsed plasma processing are discussed. (author)

 
 
 
 
201

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

202

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

International Nuclear Information System (INIS)

imum 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

203

Work function and electron affinity of some layered transition metal dichalcogenide materials  

International Nuclear Information System (INIS)

Work function and electron affinity values of various semiconducting and metallic layered transition metal dichalcogenides (TMDCs) which might be suitable for the photovoltaic applications (such as ZrSxSe2-x where 0?x?2, HfSe2, HfS2, TiTe2, NbTe2, TaS2) have been measured using photoemission spectroscopy and vibrating capacitor Kelvin probe techniques. All samples were single crystals grown by the chemical vapour transport method with iodine as a transport agent. The measured values are compared to the previously reported empirical and calculated values based on various band models, and proved good agreement for most of the materials.

204

Nanohybrid-layered double hydroxides/urease materials: Synthesis and application to urea biosensors  

International Nuclear Information System (INIS)

Nanohybrid [ZnAl]-layered double hydroxides/urease were prepared for the first time using the coprecipitation of enzyme and inorganic matrix. By varying the respective amount of urease and LDH, we obtained hybrid materials with various amount and dispersion rate of active biomolecules. X-ray diffraction and infrared spectroscopy confirm the preservation of the structure of each partner while the morphology properties are in good agreement with the permeability study. These new nanohybrids were applied for the development of urea biosensors. Biosensor responses to urea additions were obtained using capacitance (C vs. V) measurements at urease-LDH biofilm deposited on an insulated semiconductor (IS) structure

205

Microwave absorption properties of carbon nanocoils coated with highly controlled magnetic materials by atomic layer deposition.  

Science.gov (United States)

In this work, atomic layer deposition is applied to coat carbon nanocoils with magnetic Fe(3)O(4) or Ni. The coatings have a uniform and highly controlled thickness. The coated nanocoils with coaxial multilayer nanostructures exhibit remarkably improved microwave absorption properties compared to the pristine carbon nanocoils. The enhanced absorption ability arises from the efficient complementarity between complex permittivity and permeability, chiral morphology, and multilayer structure of the products. This method can be extended to exploit other composite materials benefiting from its convenient control of the impedance matching and combination of dielectric-magnetic multiple loss mechanisms for microwave absorption applications. PMID:23171130

Wang, Guizhen; Gao, Zhe; Tang, Shiwei; Chen, Chaoqiu; Duan, Feifei; Zhao, Shichao; Lin, Shiwei; Feng, Yuhong; Zhou, Lei; Qin, Yong

2012-12-21

206

Los Alamos MAWST software layered on Westinghouse Savannah River Company's nuclear materials accountability system  

International Nuclear Information System (INIS)

The Los Alamos Safeguards Systems Group's Materials Accounting With Sequential Testing (MAWST) computer program was developed to fulfill DOE Order 5633.3B requiring that inventory-difference control limits be based on variance propagation or any other statistically valid technique. Westinghouse Savannah River Company (WSRC) developed a generic computerized accountability system, NucMAS, to satisfy accounting and reporting requirements for material balance areas. NucMAS maintains the calculation methods and the measurement information required to compute nuclear material transactions in elemental and isotopic masses by material type code. The Safeguards Systems Group designed and implemented to WSRC's specifications a software interface application, called NucMASloe. It is a layered product for NucMAS that automatically formats a NucMAS data set to a format compatible with MAWST and runs MAWST. This paper traces the development of NucMASloe from the Software Requirements through the testing and demonstration stages. The general design constraints are described as well as the difficulties encountered on interfacing an external software product (MAWST) with an existing classical accounting structure (NucMAS). The lessons learned from this effort, the design, and some of the software are directly applicable to the Local Area Network Material Accountability System (LANMAS) being sponsored by DOE

207

Study on UV-shielding mechanism of layered double hydroxide materials.  

Science.gov (United States)

The development of UV-shielding materials has attracted considerable attention in the field of coatings and sunscreen. This paper reports the UV-shielding mechanism of layered double hydroxide (LDH) materials in terms of chemical composition, structure and morphology, by using (LDH/PAA)n films (n stands for bilayer number) through alternate LBL assembly of LDH nanoparticles and poly(acrylic acid) (PAA) on quartz substrates as a model system. A combination investigation based on experimental and theoretical study demonstrates that the maximum UV scattering can be achieved when ?/d ? 1.98; the introduction of Zn element is an effective way to tune the electron structure, band gap, transition mode and resulting UV-shielding property of LDH materials. A UV-shielding efficiency as high as 95% can be obtained by modulating the particle size, composition and thickness of the LDHs. Furthermore, the UV anti-aging capacity of LDH-modified bitumen was studied, which demonstrates a large improvement in UV-resistance performance of bitumen by the incorporation of LDH materials. Therefore, this work systematically discloses the relationship between UV-shielding property and chemical/structural parameters of LDH materials, which can be potentially used as anti-aging agents in various organic matrices and polymer areas. PMID:24064552

Shi, Wenying; Lin, Yanjun; Zhang, Shitong; Tian, Rui; Liang, Ruizheng; Wei, Min; Evans, David G; Duan, Xue

2013-11-01

208

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

209

Functionalization of Fibers Using Azlactone-Containing Polymers: Layer-by-Layer Fabrication of Reactive Thin Films on the Surfaces of Hair and Cellulose-Based Materials  

Digital Repository Infrastructure Vision for European Research (DRIVER)

We report an approach to the functionalization of fibers and fiber-based materials that is based on the deposition of reactive azlactone-functionalized polymers and the ‘reactive’ layer-by-layer assembly of azlactone-containing thin films. We demonstrate (i) that the azlactone-functionalized polymer poly(2-vinyl-4,4-dimethylazlactone) (PVDMA) can be used to modify the surfaces of a model protein-based fiber (horsehair) and cellulose-based materials (e.g., cotton and paper), and (ii) that ...

Buck, Maren E.; Lynn, David M.

2010-01-01

210

Cooperation of micro- and meso-porous carbon electrode materials in electric double-layer capacitors  

Energy Technology Data Exchange (ETDEWEB)

The capacitive characteristics of micro- and meso-porous carbon materials have been compared in cyclic voltammetric studies and galvanostatic charge-discharge tests. Meso-porous carbon can keep certain high capacitance values at high scan rates, whereas micro-porous carbon possesses very high capacitance values at low scan rates but fades quickly as the scan rate rises up. For better performance of electric double-layer capacitors (EDLCs), the cooperative application of both kinds of carbon materials has been proposed in the following two ways: mixing both kinds of carbons in the same electrode or using the asymmetric configuration of carbon electrodes in the same EDLC. The cooperative effect on the electrochemical performance has also been addressed. (author)

Zheng, Cheng [State Key Laboratory of Electroanalytical Chemistry, Changchun Institute of Applied Chemistry, Chinese Academy of Sciences, 5625 Renmin Street, Changchun 130022, Jilin Province (China); Graduate University of Chinese Academy of Sciences, Beijing 100039 (China); Qi, Li; Wang, Hongyu [State Key Laboratory of Electroanalytical Chemistry, Changchun Institute of Applied Chemistry, Chinese Academy of Sciences, 5625 Renmin Street, Changchun 130022, Jilin Province (China); Yoshio, Masaki [Advanced Research Center, Saga University, 1341 Yoga-machi, Saga 840-0047 (Japan)

2010-07-01

211

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

212

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

213

Colloidal-chemical properties of layer silicate dispersions used for production of highly porous glass-ceramic materials  

International Nuclear Information System (INIS)

We study the processes of structure formation in dispersions of layered silicate montmorillonite for the production of highly porous materials with the addition of glass powder by duplication of a polyurethane matrix. Rheological properties of dispersions were regulated by polyvinyl alcohol. It is established that the dense layer of glass powder is formed after the application of glass containing a dispersion on the surface of a polymer template. The thickness of this layer depends on the PVA concentration in the system.

214

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.

215

Crystallization of amorphous silicon thin films using nanoenergetic intermolecular materials with buffer layers  

Science.gov (United States)

Optimization of the crystallization of amorphous silicon (a-Si) using a mixture of nanoenergetic materials of iron oxide/aluminum (Fe 2O 3/Al) was studied. To achieve high-quality polycrystalline Si (poly-Si) thin films, silicon oxide (SiO 2) and silver (Ag) layer were deposited on the a-Si as buffer layers to prevent the metal diffusion in a-Si during thermite reaction and to transport the thermal energy released from nanoenergetic materials, respectively. Raman measurement was used to define the crystallinity of poly-Si. For molar ratio of Al and Fe of 2 with 100-nm-thick-SiO 2, Raman measurement showed the 519.59 cm -1 of peak position and the 5.08 cm -1 of full width at half maximum with 353 MPa of low tensile stress indicating high quality poly-Si thin film. These results showed that optimized thermite reaction could be used successfully in crystallization of a-Si to high -quality poly-Si thin films.

Lee, Choong Hee; Jeong, Tae Hoon; Kim, Do Kyung; Jeong, Woong Hee; Kang, Myung-Koo; Hwang, Tae Hyung; Kim, Hyun Jae

2009-02-01

216

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

217

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 cm(2)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 10(5), a field-effect mobility of 205 cm(2)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. PMID:25041752

Xia, Fengnian; Wang, Han; Jia, Yichen

2014-01-01

218

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

219

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

220

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.

 
 
 
 
221

SYNTHESIS AND ADSORPTION CHARACTERISTIC OF HUMIC/MGAL LAYERED DOUBLE HYDROXIDE HYBRID MATERIALS  

Directory of Open Access Journals (Sweden)

Full Text Available Two synthetic routes, coprecipitation and adsorption, for the incorporation of humic acid and Mg-Al layered double hydroxide (MgAl-LDH were investigated and two kinds of dark brown Humic / MgAl-LDH hybrid materials were synthesized. X-ray Diffraction (XRD, Fourier Transform Infrared Spectroscopy (FTIR, thermogravimetric analysis (TGA, total organic carbon (TOC and elemental analysis show that the stable humic anions contents in the prepared materials are 10.84% (w w-1 and 5.88% (w w-1 from coprecipitation, adsorption process, respectively, and humic anions rather bond with exposed hydrated metal ions on the subsurface of fine LDH particles than intercalate into the interlayer space. Via coprecipitation method, a Humic/LDH hybrid material with finer particle size and higher humic carbon content can be obtain. Further aqueous Zn(II adsorption experiment showed that it was a kind of favorable humic material with much higher Zn (II adsorption capacity, 181 mg g-1, than that of ordinary adsorbents in literature.

XIAOQIAN LIU

2010-12-01

222

Layer closure of laparotomy wounds with absorbable and non-absorbable suture materials.  

Science.gov (United States)

Opinions vary regarding the best suture material for abdominal wound closure. Some surgeons favour non-absorbable sutures while others use absorbable materials, but there is little objective clinical information regarding the relative merits of the different suture materials. In a randomized prospective clinical trial the synthetic absorbable polyglactin and polyglycolic acid sutures were compared with the non-absorbable polypropylene suture in the closure of 161 laparotomy wounds. A layered closure technique was used in all cases. The total incidence of wound dehiscence and herniation was 8-1 per cent, and there was no significant difference between polylycolic acid (9-6 per cent), polyglactin (5-8 per cent) and polypropylene (8-8 per cent). Dehiscence and herniation were significantly more common in wounds closed by surgeons in training. It was concluded that none of the suture materials provided satisfactory freedom from wound complications. It is possible that these sutures may prove satisfactory with an alternative technique of abdominal wound closure, but this should be the subject of further clinical studies. PMID:791437

Irvin, T T; Koffman, C G; Duthie, H L

1976-10-01

223

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

224

MODELLING OF ACOUSTIC EMISSION SIGNALS FOR THE CASE OF MATERIAL SURFACE LAYERS DISTRACTION IN THE PROCESS OF FRICTION  

Directory of Open Access Journals (Sweden)

Full Text Available  The obtained data of the resulting acoustic signals emission at the prevailing mechanism of the material surface layer wear under friction have been considered. It has been shown that the form and parameters of the acoustic emission resulting signals depend on the time of the initiation of type-I or type-II secondary structures fracture (rotation velocity of friction pair, as well as the stressed-deformed state of the materials’ surface layers of friction pairs.

Sergey F. Filonenko

2008-02-01

225

Enhanced photoconductivity in organic single-layered photoreceptors with bipolar charge transport materials  

International Nuclear Information System (INIS)

The organic single-layered photoreceptors (SLPRs) consisting of polycarbonate (PC) matrix containing dispersed N,N'-diethyl-4-aminobenzaldehyde-1-phenyl-1'-(?-naphthyl)-hydrazone (BAH) and 2,4,7-trinitrylfluorenone (TNF) as bipolar charge (hole and electron) transport materials, as well as oxotitanium phthalocyanine (TiOPc) as charge generation materials (CGMs), were prepared. The influence of organic electron transport material (ETM) on the photosensitivity in the photoreceptors was investigated. It was found that small amount of TNF (TNF/BAH ?0.005) could improve the photosensitivity of photoreceptors greatly, i.e. the enhanced photoconductive effect, but the further increase of TNF concentration would lead to the decline of the photosensitivity. Differential scanning calorimeter (DSC), UV-Vis and cyclic voltammograms (CV) study showed that the enhanced photoconductivity might be resulted from the improvement of the separation efficiency of electron-hole pairs, and the decline of photosensitivity was due to the formation of the charge transfer complex (CTC) of TNF-BAH

226

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

International Nuclear Information System (INIS)

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.

227

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)

228

New magnetic materials obtained by ion-exchange reactions from non-magnetic layered perovskites  

International Nuclear Information System (INIS)

New layered magnetic materials (MCl)Ca2Ta3O10 (M = Cu, Fe), have been prepared by ion-exchange reactions of non-magnetic perovskite derivatives, ACa2Ta3O10 (A = Rb, Li), in corresponding anhydrous molten salts. Powder x-ray diffraction patterns of the products are successfully indexed assuming tetragonal symmetry with cell dimensions a = 3.829 A and c = 15.533 A for Cu, and a = 3.822 A and c = 15.672 A for Fe. Being separated by the Ca2Ta3O10 triple-layer perovskite slabs, the transition-metal chloride (MCl) network provides a two-dimensional magnetic lattice. Magnetic susceptibility measurements show that (CuCl)Ca2Ta3O10 is in an antiferromagnetic state below 8 K, while (FeCl)Ca2Ta3O10 has two anomalies at 91 and 125 K, suggesting successive phase transitions due to geometrical spin frustration

229

New magnetic materials obtained by ion-exchange reactions from non-magnetic layered perovskites  

Energy Technology Data Exchange (ETDEWEB)

New layered magnetic materials (MCl)Ca{sub 2}Ta{sub 3}O{sub 10} (M = Cu, Fe), have been prepared by ion-exchange reactions of non-magnetic perovskite derivatives, ACa{sub 2}Ta{sub 3}O{sub 10} (A = Rb, Li), in corresponding anhydrous molten salts. Powder x-ray diffraction patterns of the products are successfully indexed assuming tetragonal symmetry with cell dimensions a = 3.829 A and c = 15.533 A for Cu, and a = 3.822 A and c = 15.672 A for Fe. Being separated by the Ca{sub 2}Ta{sub 3}O{sub 10} triple-layer perovskite slabs, the transition-metal chloride (MCl) network provides a two-dimensional magnetic lattice. Magnetic susceptibility measurements show that (CuCl)Ca{sub 2}Ta{sub 3}O{sub 10} is in an antiferromagnetic state below 8 K, while (FeCl)Ca{sub 2}Ta{sub 3}O{sub 10} has two anomalies at 91 and 125 K, suggesting successive phase transitions due to geometrical spin frustration.

Kageyama, H [Department of Chemistry, Graduate School of Science, Kyoto University, Kyoto 606-8502 (Japan); Viciu, L [Department of Chemistry and the Advanced Materials Research Institute, University of New Orleans, New Orleans, LA 70148-2820 (United States); Caruntu, G [Department of Chemistry and the Advanced Materials Research Institute, University of New Orleans, New Orleans, LA 70148-2820 (United States); Ueda, Y [Institute for Solid State Physics, University of Tokyo, Kashiwa, Chiba 277-8581 (Japan); Wiley, J B [Department of Chemistry and the Advanced Materials Research Institute, University of New Orleans, New Orleans, LA 70148-2820 (United States)

2004-03-24

230

Periodic materials-based vibration attenuation in layered foundations: experimental validation  

International Nuclear Information System (INIS)

Guided by the recent advances in solid-state research in periodic materials, a new type of layered periodic foundation consisting of concrete and rubber layers is experimentally investigated in this paper. The distinct feature of this new foundation is its frequency band gaps. When the frequency contents of a wave fall within the range of the frequency band gaps, the wave, and hence its energy, will be weakened or cannot propagate through the foundation, so the foundation itself can serve as a vibration isolator. Using the theory of elastodynamics and the Bloch–Floquet theorem, the mechanism of band gaps in periodic composites is presented, and a finite element model is built to show the isolation characteristic of a finite dimensional periodic foundation. Based on these analytical results, moreover, a scaled model frame and a periodic foundation were fabricated and shake table tests of the frame on the periodic foundation were performed. Ambient, strong and harmonic vibration attenuations are found when the exciting frequencies fall into the band gaps. (fast track communication)

231

Periodic materials-based vibration attenuation in layered foundations: experimental validation  

Science.gov (United States)

Guided by the recent advances in solid-state research in periodic materials, a new type of layered periodic foundation consisting of concrete and rubber layers is experimentally investigated in this paper. The distinct feature of this new foundation is its frequency band gaps. When the frequency contents of a wave fall within the range of the frequency band gaps, the wave, and hence its energy, will be weakened or cannot propagate through the foundation, so the foundation itself can serve as a vibration isolator. Using the theory of elastodynamics and the Bloch-Floquet theorem, the mechanism of band gaps in periodic composites is presented, and a finite element model is built to show the isolation characteristic of a finite dimensional periodic foundation. Based on these analytical results, moreover, a scaled model frame and a periodic foundation were fabricated and shake table tests of the frame on the periodic foundation were performed. Ambient, strong and harmonic vibration attenuations are found when the exciting frequencies fall into the band gaps.

Xiang, H. J.; Shi, Z. F.; Wang, S. J.; Mo, Y. L.

2012-11-01

232

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

233

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)

234

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

International Nuclear Information System (INIS)

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, thermo sprayed aluminum (3-year evaluation) and conventional Al/Zn/In anodes 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 thermo sprayed aluminum type can not be used in prestressed concrete piles because the very negative potentials (4) they supply to the reinforcement could lead to hydrogen embrittlement. (Author) 16 refs

235

Effect of Alclad Layer on Material Flow and Defect Formation in Friction-Stir-Welded 2024 Aluminum Alloy  

Science.gov (United States)

The effect of the Alclad layer on material flow and defect formation during friction-stir welding (FSW) of 6.5-mm-thick 2024Al-T351 alloy plates was investigated. To characterize the material flow during FSW, different cross sections of the keyhole and "stop-action weld" were made for metallographic observations. It was found that the top Alclad assembled at the shoulder/workpiece interface, thereby weakening the material flow in the shoulder-driven zone and favoring the formation of void defect at high traveling speeds. The bottom Alclad layer extended into the weld at excess material flow state, which could be avoided at balanced material flow state. A conceptual model of material flow was proposed to describe the formation of the weld. It was indicated that a perfect FSW joint of Alclad 2024Al alloy without defect could be obtained at an optimum FSW condition.

Zhang, Z.; Xiao, B. L.; Wang, D.; Ma, Z. Y.

2011-06-01

236

Natural convection around a horizontal solid cylinder wrapped with a layer of fibrous or porous material  

International Nuclear Information System (INIS)

Heat losses in duct flow and heat transfer enhancement are investigated through an analysis of natural convection about a horizontal cylinder with a porous or fibrous coating. The porous substrate may be used for two purposes. According to its properties, it may be employed as an insulating material or as a means to surface augmentation. An optimization study is then carried out in order to find the best conditions that allow good thermal insulation or heat transfer rate improvement. The flow motion and heat transfer coefficient are predicted for various conditions. The results show that an efficient insulation which means less than 10% in heat losses is obtained for a porous layer thickness of 0.8x tube diameter and a permeability corresponding to Da ? 10-7. Nevertheless, there is a Darcy number limit above which convection must be accounted for. Porous or fibrous materials may also be used as a heat transfer augmentation technique. To achieve this goal, porous media with high permeability and/or high effective thermal conductivity must be selected

237

On the mechanism of oxide layer formation on surfaces of structural materials in aqueous medium at high temperatures and protective properties of such layers  

International Nuclear Information System (INIS)

In high-temperature water a magnetite layer is formed on steel that inhibits further corrosion of the matrix material. Complexon treatment has proved a success for purposeful and more rapid formation of such a protective layer. During the first step of that treatment iron complexonates are formed at temperatures of about 1500C which are decomposed by thermolysis in the following step at a temperature of 2900C and higher yielding a magnetite layer on the steel surface. With this, special requirements arise for both the state of metallic surface and the reaction conditions. Analogically to thermolytic decomposition of the complexonates, a radiolytical decomposition is also possible. Complexon treatment with a view to increasing corrosion resistance is also applicable to various metals present in a system. Deposition on the corresponding matrix takes place according to Dankov's principle of structural equality. Complexon treatment has special importance for zirconium alloys to prevent hydrogen absorption. (author)

238

Biofabrication of multi-material anatomically shaped tissue constructs  

International Nuclear Information System (INIS)

Additive manufacturing in the field of regenerative medicine aims to fabricate organized tissue-equivalents. However, the control over shape and composition of biofabricated constructs is still a challenge and needs to be improved. The current research aims to improve shape, by converging a number of biocompatible, quality construction materials into a single three-dimensional fiber deposition process. To demonstrate this, several models of complex anatomically shaped constructs were fabricated by combined deposition of poly(vinyl alcohol), poly(?-caprolactone), gelatin methacrylamide/gellan gum and alginate hydrogel. Sacrificial components were co-deposited as temporary support for overhang geometries and were removed after fabrication by immersion in aqueous solutions. Embedding of chondrocytes in the gelatin methacrylamide/gellan component demonstrated that the fabrication and the sacrificing procedure did not affect cell viability. Further, it was shown that anatomically shaped constructs can be successfully fabricated, yielding advanced porous thermoplastic polymer scaffolds, layered porous hydrogel constructs, as well as reinforced cell-laden hydrogel structures. In conclusion, anatomically shaped tissue constructs of clinically relevant sizes can be generated when employing multiple building and sacrificial materials in a single biofabrication session. The current techniques offer improved control over both internal and external construct architecture underscoring its potential to generate customized implants for human tissue regeneration. (paper)

239

Multiple layers of self-asssembled Ge/Si islands: Photoluminescence, strain fields, material interdiffusion, and island formation  

International Nuclear Information System (INIS)

Strain fields in stacked layers of vertically aligned self-assembled Ge islands on Si(100) can cause a reduction of the wetting layer thickness in all but the initial layer and hence induce an energy separation ?Ewl between the energy transitions of the different wetting layers. Our systematic photoluminescence (PL) study on twofold stacked Ge/Si layers shows that the quantity ?Ewl is a sensitive function of the Si spacer thickness and reflects the degree of strain field interaction between the island layers. Pronounced PL blueshifts are also observed for the island related energy transition in twofold and multifold island layers. We suggest that with increasing number of stacked island layers strain field superposition of buried islands causes enhanced SiGe material intermixing during Si overgrowth of the islands. This effect naturally explains the strong PL blueshift of the island related energy transition. Recently observed shape transformations in stacked Ge islands are well explained by our model of superimposed strain fields. We also discuss the initial stages of island formation in the second Ge layer of twofold island stacks. Many of the effects observed in this paper on the Ge/Si system are probably also important for self-assembling III/V islands but due to extremely small sizes are much harder to evaluate

240

Compressive Failure Mechanisms in Layered Materials : PhD Thesis Defended in public at Aalborg University (120808)  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Two important failure modes in fiber reinforced composite materials in cluding layers and laminates occur under loading conditions dominated by compression in the layer direction. These two distinctly different failure modes are 1. buckling driven delamination 2. failure by strain localization into kink bands. The present thesis falls into two parts dealing with the two failure modes. In the first part of the thesis the effects of system geometry on buckling driven delamination is investigate...

Sørensen, Kim Dalsten

2008-01-01

 
 
 
 
241

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

Directory of Open Access Journals (Sweden)

Full Text Available 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 as Mg-rich primers as a sacrificial anode pigment to protect aerospace grade aluminum alloys against corrosion. Mg-rich primers have performed very well on aluminum alloys when compared against the current chromate standard, but the carcinogenic chromate-based coatings/pretreatments are being widely used by the Department of Defense (DoD to protect its infrastructure and fleets against corrosion damage. Factors such as reactivity of Mg particles in the coating matrix during exposure to aggressive corrosion environments, interaction of atmospheric gases with Mg particles and the impact of Mg dissolution, increases in pH and hydrogen gas liberation at coating-metal interface, and primer adhesion need to be considered for further development of Mg-rich primer technology.

Michael D. Blanton

2012-09-01

242

Sacrificial template growth of CdS nanotubes from Cd(OH)2 nanowires  

International Nuclear Information System (INIS)

A diffusion-controlled process was proposed for the preparation of inorganic nanotubes from nanowires. The preformed Cd(OH)2 nanowires were used as the sacrificial templates to generate CdS nanotubes with different wall thickness. The axle-sleeve transition state found in-between the precursor and the formation of products proves the diffusion-controlled mechanism. CdS nanotubes can be prepared via this method at different temperature and with various sulfide sources. X-ray diffraction (XRD) and high-resolution transmission electron microscopy (HRTEM) results showed that all obtained CdS nanotubes consist conglomerated crystallites, and the crystallinity can be altered by changing the temperature of the growth process. The wall thickness of the produced CdS nanotubes can be controlled by changing the concentration of the sulfide source and stopping the reaction at different stages. -- Graphical abstract: CdS nanotubes were prepared with Cd(OH)2 nanowires as the sacrificial templates. Diffusion played an important role in the process. The morphology of the produced nanotubes can be varied by alternating the reaction conditions

243

Highly interconnected porous electrodes for dye-sensitized solar cells using viruses as a sacrificial template  

Energy Technology Data Exchange (ETDEWEB)

A novel means of generating highly interconnected and nano-channeled photoelectrodes by employing one-dimensionally shaped M13 viruses as a sacrificial template is proposed for highly efficient dye-sensitized solar cells (DSSCs). The electrostatic binding between oppositely charged TiO{sub 2} nanoparticles and M13 viruses provides a uniform complexation and suppresses random aggregation of TiO{sub 2} nanoparticles. After the calcination process, the traces of viruses leave porously interconnected channel structures inside TiO{sub 2} nanoparticles, providing efficient paths for electrolyte contact as well as increased surface sites for dye adsorption. As a result, DSSCs generated using a sacrificial virus template exhibit an enhanced current density (J{sub SC}) of 12.35 mA cm-{sup 2} and a high photoconversion efficiency ({eta}) of 6.32%, greater than those of conventional photoelectrodes made of TiO{sub 2} nanoparticles (J{sub SC} of 8.91 mA cm-{sup 2} and {eta} of 4.67%). In addition, the stiffness and shape of the M13 virus can be varied, emphasizing the usefulness of the one-dimensional structural characteristics of M13 viruses for the highly interconnected porous structure of DSSC photoelectrodes. (Copyright copyright 2011 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

Lee, Yong Man; Kim, Young Hun; Lee, Jun Haeng; Park, Jong Hyeok; Park, Nam-Gyu; Choe, Woo-Seok; Yoo, Pil J. [School of Chemical Engineering, SKKU Advanced Institute of Nanotechnology (SAINT), Sungkyunkwan University, Suwon 440-746 (Korea, Republic of); Ko, Min Jae [Solar Cell Center, Korea Institute of Science and Technology (KIST), Seoul 136-791 (Korea, Republic of)

2011-03-22

244

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

245

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

246

Synthesis, characterization, and application of novel microporous mixed metal oxides, and nanostructured layered material-polymer films  

Science.gov (United States)

Zeolites are microporous crystalline aluminosilicates with pores and cavities of molecular dimension. They consist of interconnected aluminum and silicon tetrahedra to build a variety of 3D open framework structures. Due to their structure, stability, and activity, zeolites have been widely used in a broad variety of applications in industry. It is, therefore, of great interest to make new structures with potentially novel properties. In this regard, there has recently been a growing interest in the synthesis of novel mixed metal oxides with octahedral and tetrahedral units owing to the possibility to find unique electronic and optical properties. Hence, these materials can find advanced applications as well as conventional applications, just like zeolites. Research efforts have led to the discovery of several mixed octahedral and tetrahedral metal oxides with novel crystal structures including titanium silicates and cerium silicate. Layered materials with transport paths along the thickness of the layers are of particular interest due to potential usage as selective layers of nanometer scale in nanocomposite membranes. A new layered silicate (we call AMH-3) has been synthesized under hydrothermal conditions. The crystal structure solution via powder X-ray diffraction has revealed its unique layer structure of three dimensional microporosity within layers. Layered materials with porous layers will open up new areas of applications, such as selective nanocomposite separation membranes. Polymer/selective-flake nanocomposite membranes have been fabricated for the first time, which can, in principle, be scaled down to submicrometer structures. A layered aluminophosphate with a porous net layer is used as a selective phase and a polyimide as a continuous phase. The microstructures of the nanocomposite membranes were investigated using various characterization techniques. Nanocomposite membranes with 10 wt% layered aluminophosphate show substantial enhancement in performance with oxygen selectivity over nitrogen as high as 8.9 (as compared to 3.6 of pure polymer) and carbon dioxide selectivity over methane as high as 40.9 (as compared to 13.4 of pure polymer) in room temperature permeation measurements. This improved performance, along with permeability estimation through the aluminophosphate layers with a semiempirical model, suggests that the layered aluminophosphate acts as a molecular sieve favoring smaller molecules.

Jeong, Hae-Kwon

247

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

Science.gov (United States)

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.

Pustovalov, V. K.; Astafyeva, L. G.; Zharov, V. P.

2013-12-01

248

Low temperature silicon dioxide by thermal atomic layer deposition: Investigation of material properties  

Science.gov (United States)

SiO2 is the most widely used dielectric material but its growth or deposition involves high thermal budgets or suffers from shadowing effects. The low-temperature method presented here (150 °C) for the preparation of SiO2 by thermal atomic layer deposition (ALD) provides perfect uniformity and surface coverage even into nanoscale pores, which may well suit recent demands in nanoelectronics and nanotechnology. The ALD reaction based on 3-aminopropyltriethoxysilane, water, and ozone provides outstanding SiO2 quality and is free of catalysts or corrosive by-products. A variety of optical, structural, and electrical properties are investigated by means of infrared spectroscopy, UV-Vis spectroscopy, secondary ion mass spectrometry, capacitance-voltage and current-voltage measurements, electron spin resonance, Rutherford backscattering, elastic recoil detection analysis, atomic force microscopy, and variable angle spectroscopic ellipsometry. Many features, such as the optical constants (n, k) and optical transmission and surface roughness (1.5 Å), are found to be similar to thermal oxide quality. Rapid thermal annealing (RTA) at 1000 °C is demonstrated to significantly improve certain properties, in particular by reducing the etch rate in hydrofluoric acid, oxide charges, and interface defects. Besides a small amount of OH groups and a few atomic per mille of nitrogen in the oxide remaining from the growth and curable by RTA no impurities could be traced. Altogether, the data point to a first reliable low temperature ALD-growth process for silicon dioxide.

Hiller, D.; Zierold, R.; Bachmann, J.; Alexe, M.; Yang, Y.; Gerlach, J. W.; Stesmans, A.; Jivanescu, M.; Müller, U.; Vogt, J.; Hilmer, H.; Löper, P.; Künle, M.; Munnik, F.; Nielsch, K.; Zacharias, M.

2010-03-01

249

A sodium layered manganese oxides as 3 V cathode materials for secondary lithium batteries  

International Nuclear Information System (INIS)

The synthesis of a new anhydrous sodium manganese oxide ?-Na0.66MnO2.13 obtained via a sol-gel process in organic medium is reported. The partial and limited removal of sodium ions from the layered host lattice (hexagonal symmetry; a = 2.84 A, c = 11.09 A) allows to get a high and stable specific capacity of 180 mAh g-1 at C/20 in the cycling limits 4.3/2 V with a mean working voltage of 3 V without the emergence of a spinel phase. By introducing acetylene black in solution during the sol-gel reaction, a composite material containing 8 wt.% AB has been obtained. The rate capability is shown to be significantly improved leading to an increase of the available specific capacity with for instance 200 and 90 mAh g-1 at C/20 and C rate. This effect is ascribed to a better electronic contact between particles and/or the modification of the oxide surface which makes the intercalation process more homogeneous and more efficient

250

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

251

Conceptual material design for magnetic tunneling junction cap layer for high magnetoresistance ratio  

Science.gov (United States)

A conceptual material design for magnetic tunneling junction cap layer realizing a steep NiFe/AlOx interface is proposed. Tunnel magneto resistance stack of cap/NiFe/AlOx/CoFe/Ru/CoFe/PtMn/Ta//sub was prepared. Maximum magnetoresistance (MR) ratios of nonmagnetic-NiFeZr, Zr, Ta, Ru, and Rh caps at 0 V were 55%, 28%, 50%, 43%, and 42%, respectively. The decrease of MR ratio and the increase of resistance area product RA with Ru cap compared to Ta cap correlate with the partial oxidation of the NiFe/AlOx interface occurring in additional postannealing, which was confirmed by focused-ion-beam-transmission-electron-microscope-energy-dispersive-x-ray-fluorescence observation. Since standard electrode potential is TaNiFeZr alloy cap and the highest MR ratio of 55% was realized, without suffering from the diffusion of Zr. The highest MR ratio with nonmagnetic-NiFeZr cap is consistent with the lowest electrode potential of Zr, and we believe that nonmagnetic-NiFeZr cap realizes a steep NiFe/AlOx interface without the oxidation of NiFe.

Nagamine, M.; Nagase, T.; Nishiyama, K.; Yoshikawa, M.; Amano, M.; Asao, Y.; Ikegawa, S.; Yoda, H.; Honjo, H.; Mori, K.; Ishiwata, N.; Tahara, S.

2006-04-01

252

Energy loss spectrum of swift charged particles penetrating a layer of material  

International Nuclear Information System (INIS)

The energy loss spectrum of a beam of charged particles penetrating a layer of random material has been analyzed theoretically. A steepest-descent evaluation of the Bothe-Landau integral yields general expressions for the spectrum, the most probable energy loss, and the halfwidth, without reference to a particular collision cross section. The procedure has been tested against rigorous results for model cross sections as well as the Landau-Vavilov theory for free-Coulomb scattering. The most probable energy loss is found to be systematically smaller than the mean energy loss by an amount which is independent of foil thickness for not-too-thin foils. This peak shift turns out to be insensitive to the angle of emergence from the foil but sensitive to nonuniformities in foil thickness and to detector resolution. The influence of shell corrections on the spectrum has been discussed, and the peak shift has been evaluated explicitly for the Landau-Vavilov case, for moderately relativistic ions, for slow ions stopped in a free electron gas, and for heavy ions stopped by elastic collisions. A procedure has been outlined for determining stopping power and straggling from measured peak energy losses and halfwidths. Systematic errors may be present in current stopping power data, caused by the use of most probable instead of mean energy loss values. Estimated peak shifts compare well with recent experimental results. (orig.)

253

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

254

Simulation of trapping properties of high {kappa} material as the charge storage layer for flash memory application  

Energy Technology Data Exchange (ETDEWEB)

We investigated the trapping properties of high {kappa} material as the charge storage layer in non-volatile flash memory devices using a two-dimensional device simulator, Medici. The high {kappa} material is sandwiched between two silicon oxide layers, resulting in the Silicon-Oxide-High {kappa}-Oxide-Silicon (SOHOS) structure. The trap energy levels of the bulk electron traps in high {kappa} material were determined. The programming and erasing voltage and time using Fowler Nordheim tunneling were estimated by simulation. The effect of deep level traps on erasing was investigated. Also, the effect of bulk traps density, thickness of block oxide and thickness of high {kappa} material on the threshold voltage of the device was simulated.

Yeo, Yee Ngee [Silicon Nano Device Laboratory, Department of Electrical and Computer Engineering, National University of Singapore, 4 Engineering Drive 3, Singapore 117576 (Singapore); Wang Yingqian [Silicon Nano Device Laboratory, Department of Electrical and Computer Engineering, National University of Singapore, 4 Engineering Drive 3, Singapore 117576 (Singapore); Samanta, Santanu Kumar [Silicon Nano Device Laboratory, Department of Electrical and Computer Engineering, National University of Singapore, 4 Engineering Drive 3, Singapore 117576 (Singapore); Yoo, Won Jong [Silicon Nano Device Laboratory, Department of Electrical and Computer Engineering, National University of Singapore, 4 Engineering Drive 3, Singapore 117576 (Singapore)]. E-mail: eleyoowj@nus.edu.sg; Samudra, Ganesh [Silicon Nano Device Laboratory, Department of Electrical and Computer Engineering, National University of Singapore, 4 Engineering Drive 3, Singapore 117576 (Singapore); Gao, Dongyue [Silicon Nano Device Laboratory, Department of Electrical and Computer Engineering, National University of Singapore, 4 Engineering Drive 3, Singapore 117576 (Singapore); Chong, Chee Ching [Institute of High Performance Computing, 1 Science Park Rd. Singapore Science Park II, Singapore 117528 (Singapore)

2006-05-10

255

Atomic layer deposition of HfxAlyCz as a work function material in metal gate MOS devices  

International Nuclear Information System (INIS)

As advanced silicon semiconductor devices are transitioning from planar to 3D structures, new materials and processes are needed to control the device characteristics. Atomic layer deposition (ALD) of HfxAlyCz films using hafnium chloride and trimethylaluminum precursors was combined with postdeposition anneals and ALD liners to control the device characteristics in high-k metal-gate devices. Combinatorial process methods and technologies were employed for rapid electrical and materials characterization of various materials stacks. The effective work function in metal–oxide–semiconductor capacitor devices with the HfxAlyCz layer coupled with an ALD HfO2 dielectric was quantified to be mid-gap at ?4.6?eV. Thus, HfxAlyCz is a promising metal gate work function material that allows for the tuning of device threshold voltages (Vth) for anticipated multi-Vth integrated circuit devices

256

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

Digital Repository Infrastructure Vision for European Research (DRIVER)

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. T...

Ould Brahim, M. S.; I Diagne, S. Tamba

2011-01-01

257

Determination of interfacial layers in high - k ALD nanolaminate materials by ARXPS and SRXPS measurements  

International Nuclear Information System (INIS)

The interfacial layers of high dielectric constant (high-k) nanolaminate films are here explored. Problems concerning ALD nanolaminate layers deals mainly with lack of accurate methods to determine in depth profile of few nm thick stacks. Modified angle resolved XPS (ARXPS) and synchrotron radiation XPS(SRXPS) are proposed as methods suitable in layer profiling. Studied stacks containing ZrO/HfO or AlO/ZrO, were prepared on Si substrates by atomic layer deposition (ALD). Two sets of experiments were covered. First dealt with initial growth (up to 20 cycles, with thickness d<2 nm) of AlO/ZrO and included layer by layer insitu investigation by SRXPS. Second experiment refer to industrial grown ZrO/HfO films (d?3 nm) processed with various parameters resulting in both, layer by layer and homogenous depositions. For those samples ex situ XPS, with angle dependent variation of probing depth, measurements were covered. By comparing obtained intensity ratios for different angles with computational developed stack model it was found that no simple layer by layer but some intermixing growth occurred including interaction with silicon substrate.

258

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

259

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 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)

260

Molecular simulation of adsorption and separation of mixtures of short linear alkanes in pillared layered materials at ambient temperature.  

Science.gov (United States)

Grand canonical Monte Carlo and configurational-bias Monte Carlo techniques are carried out to simulate the adsorption of ternary and quaternary mixtures of short linear alkanes, involving methane, ethane, propane, and n-butane, in pillared layered materials at ambient temperature, T=300 K. In the simulation, a pillared layered pore is modeled by a uniform distribution of pillars between two layered walls built by making two separate talc lamellas parallel each other with a given size of interlayer distance. The interaction between fluid molecules and two layered walls is measured by storing potentials calculated in advance at a series of grid points. The interaction between fluid molecules and pillars is also calculated by a site-to-site method. The potential model proposed in this work is proved to be effective because of the simulation result being good agreement with the experimental data for the adsorption of nitrogen at 77 K. Then, the adsorption isotherms of mixtures of short linear alkanes in pillared layered pores with three different porosities psi=0.98, 0.93 and 0.85, and three pore widths H=1.02, 1.70 and 2.38 nm at 300 K are obtained by taking advantage of the model. The simulation results tell us that the longer chain component is preferentially adsorbed at low pressures, and its adsorption increases and then decreases as the pressure increases while the shorter chain component is still adsorbed at high pressures. Moreover, the sorption selectivity of pillared layered materials for the longest chain component in alkane mixtures increases as the mole fraction of methane in the gas phase increases. The selectivity of pillared layered materials for the longest chain component in alkane mixtures also increases as the pore width decreases and the porosity increases. PMID:17482203

Li, Wen-Zhuo; Liu, Zi-Yang; Che, Yu-Liang; Zhang, Dan

2007-08-15

 
 
 
 
261

Neutron analysis for microvoids in an adhesive layer between high x-ray attenuation materials  

International Nuclear Information System (INIS)

We demonstrate the potential of neutron systems for detecting microscale defects in a thin epoxy adhesive layer between two metal plates. Neutron tomography has been used to ascertain the internal structure of the adhesive layer. The distribution of defects including microvoids is found in three-dimensionally reconstructed models that are obtained from neutron tomography images and is compared with that obtained from a magnified real image of the layer. From the results, we find that a neutron system can be the most suitable tool for detecting microscale defects in a thin adhesive layer that lies between two high X-ray attenuation plates. (author)

262

The pancreas of sacrificial animals as an object of divination for the indigenous peoples on the Island of Sumba, Indonesia.  

Science.gov (United States)

This paper describes contemporary 'intestinal' divination with the pancreas by indigenous people in Indonesia and explores the feasibility of comparing it to ancient intestinal divination. To our knowledge, divinatory use of the pancreas of sacrificial animals (chickens) has not yet been described in the literature. PMID:16015018

Sachs, Michael; Mulvahill, Matthew; Dapawole, Yance Lele

2005-01-01

263

Preparation of multi-shelled conductive polymer hollow microspheres by using Fe3O4 hollow spheres as sacrificial templates.  

Science.gov (United States)

Multi-shelled conductive polymer hollow microspheres were successfully generated by using Fe3O4 hollow microspheres as sacrificial templates via a programmed reaction-temperature process. Moreover, the multi-shelled PEDOT microspheres exhibited superb microwave absorption performance. PMID:25189419

Pang, Rui; Hu, Xiujie; Zhou, Shuyun; Sun, Chenghua; Yan, Jun; Sun, Xingming; Xiao, Shizhuo; Chen, Ping

2014-09-18

264

Synthesis of layered cathode material Li[Co xMn 1-x]O 2 from layered double hydroxides precursors  

Science.gov (United States)

Cathode materials Li[Co xMn 1-x]O 2 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·H 2O: 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 xMn 1-x]O 2 with ?-NaFeO 2 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 xMn 1-x]O 2, 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 xMn 1-x]O 2 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 behavior, with a reversible capacity of 122.5 mAh g -1 for the layered material Li[Co 0.80Mn 0.20]O 2.

Lu, Yanluo; Wei, Min; Yang, Lan; Li, Congju

2007-05-01

265

Zinc sacrificial anode behavior at elevated temperatures in sodium chloride and tap water environments  

International Nuclear Information System (INIS)

Zinc sacrificial anode coupled to mild steel was tested in sodium chloride and tap water environments at elevated temperatures. The anode failed to protect the mild steel specimens in tap water environment at all temperatures specified for this study. This was partly due to the high resistivity of the medium. The temperature factor did not help to activate the anode in water tap medium. In sodium chloride environment the anode demonstrated good protection for steel cathodes. In tap water environment the anode weight loss was negligible. The zinc anode suffered intergranular corrosion in sodium chloride environment and this was noticed starting at 40 degree centigrade. In tap water environment the zinc anode demonstrated interesting behavior beyond 60 degree centigrade, that could be attributed to the phenomenon of reversal of potential at elevated temperatures. It also showed shallow pitting spots in tap water environment without any sign of intergranular corrosion. Zinc anodes would suffer intergranular corrosion at high temperatures. (author)

266

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

267

Molecular engineering of fracture energy dissipating sacrificial bonds into cellulose nanocrystal nanocomposites.  

Science.gov (United States)

Even though nanocomposites have provided a plethora of routes to increase stiffness and strength, achieving increased toughness with suppressed catastrophic crack growth has remained more challenging. Inspired by the concepts of mechanically excellent natural nanomaterials, one-component nanocomposites were fabricated involving reinforcing colloidal nanorod cores with polymeric grafts containing supramolecular binding units. The concept is based on mechanically strong native cellulose nanocrystals (CNC) grafted with glassy polymethacrylate polymers, with side chains that contain 2-ureido-4[1H]-pyrimidone (UPy) pendant groups. The interdigitation of the grafts and the ensuing UPy hydrogen bonds bind the nanocomposite network together. Under stress, UPy groups act as sacrificial bonds: simultaneously providing adhesion between the CNCs while allowing them to first orient and then gradually slide past each other, thus dissipating fracture energy. We propose that this architecture involving supramolecular binding units within side chains of polymer grafts attached to colloidal reinforcements opens generic approaches for tough nanocomposites. PMID:24706578

McKee, Jason R; Huokuna, Johannes; Martikainen, Lahja; Karesoja, Mikko; Nykänen, Antti; Kontturi, Eero; Tenhu, Heikki; Ruokolainen, Janne; Ikkala, Olli

2014-05-12

268

Functionalization of fibers using azlactone-containing polymers: layer-by-layer fabrication of reactive thin films on the surfaces of hair and cellulose-based materials.  

Science.gov (United States)

We report an approach to the functionalization of fibers and fiber-based materials that is based on the deposition of reactive azlactone-functionalized polymers and the "reactive" layer-by-layer assembly of azlactone-containing thin films. We demonstrate (i) that the azlactone-functionalized polymer poly(2-vinyl-4,4-dimethylazlactone) (PVDMA) can be used to modify the surfaces of a model protein-based fiber (horsehair) and cellulose-based materials (e.g., cotton and paper), and (ii) that fibers functionalized in this manner can be used to support the fabrication of covalently cross-linked and reactive polymer multilayers assembled using PVDMA and poly(ethyleneimine) (PEI). The growth, chemical reactivity, and uniformity of films deposited on these substrates were characterized using fluorescence microscopy, confocal microscopy, and scanning electron microscopy (SEM). In addition to the direct functionalization of fibers, we demonstrate that the residual azlactone functionality in PVDMA-treated or film-coated fibers can be exploited to chemically modify the surface chemistry and physicochemical properties of fiber-based materials postfabrication using amine functionalized molecules. For example, we demonstrate that this approach permits control over the surface properties of paper (e.g., absorption of water) by simple postfabrication treatment of film-coated paper with the hydrophobic amine n-decylamine. The azlactone functionality present in these materials provides a platform for the modification of polymer-treated and film-coated fibers with a broad range of other chemical and biological species (e.g., enzymes, peptides, catalysts, etc.). The results of this investigation thus provide a basis for the functionalization of fibers and fiber-based materials (e.g., textile fabrics or nonwoven mats) of potential utility in a broad range of consumer, industrial, and biomedical contexts. PMID:20402471

Buck, Maren E; Lynn, David M

2010-05-01

269

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

International Nuclear Information System (INIS)

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

270

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

271

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

272

A study of Al-Zn-Sn alloy sacrificial anode cathodic protection requirements for structure used in seawater  

International Nuclear Information System (INIS)

Full text: The study will be focused on the alloying of Aluminum alloy sacrificial anode. The work will explore, evaluate and assess the effectiveness of Al-Zn-Sn alloy sacrificial anode tested in tropical seawater. This study is directed toward the development of new and more comprehensive data that will provide a technical basis for improved, more cost - effective guidelines for prediction, verification and optimization of cathodic protection requirements for structures used in tropical seawater. Furthermore, this study will also evaluate the potential and benefits of laboratory research upon marine corrosion without needed to be in the actual marine environment. The influence of alloy composition on the electrochemical properties of this Al-Zn-Sn will be determined by various tasks of testing which fully conducted in the laboratory. SEM and EDAX analysis will be employed in order to characterize surface structure of Al-Zn-Sn alloy. The corrosion measurement analyzer will be used by means to identify the electrochemical properties such as potential, corrosion rate and passivation of Al-Zn-Sn sacrificial anode when immersed in seawater. The relationship between morphological structure and electrochemical results will be examined. The data obtained will be used to evaluate the performance of Al-Zn-Sn alloy as a sacrificial anode cathodic protection for structure used in tropical seawater. Further verification will be made to testify that the Al-Zn-Sn alloy meets the qestify that the Al-Zn-Sn alloy meets the quality requirements to be used as a sacrificial anode in tropical seawater. (author)

273

Can Sacrificial Feeding Areas Protect Aquatic Plants from Herbivore Grazing? Using Behavioural Ecology to Inform Wildlife Management  

Science.gov (United States)

Effective wildlife management is needed for conservation, economic and human well-being objectives. However, traditional population control methods are frequently ineffective, unpopular with stakeholders, may affect non-target species, and can be both expensive and impractical to implement. New methods which address these issues and offer effective wildlife management are required. We used an individual-based model to predict the efficacy of a sacrificial feeding area in preventing grazing damage by mute swans (Cygnus olor) to adjacent river vegetation of high conservation and economic value. The accuracy of model predictions was assessed by a comparison with observed field data, whilst prediction robustness was evaluated using a sensitivity analysis. We used repeated simulations to evaluate how the efficacy of the sacrificial feeding area was regulated by (i) food quantity, (ii) food quality, and (iii) the functional response of the forager. Our model gave accurate predictions of aquatic plant biomass, carrying capacity, swan mortality, swan foraging effort, and river use. Our model predicted that increased sacrificial feeding area food quantity and quality would prevent the depletion of aquatic plant biomass by swans. When the functional response for vegetation in the sacrificial feeding area was increased, the food quantity and quality in the sacrificial feeding area required to protect adjacent aquatic plants were reduced. Our study demonstrates how the insights of behavioural ecology can be used to inform wildlife management. The principles that underpin our model predictions are likely to be valid across a range of different resource-consumer interactions, emphasising the generality of our approach to the evaluation of strategies for resolving wildlife management problems. PMID:25077615

Wood, Kevin A.; Stillman, Richard A.; Daunt, Francis; O'Hare, Matthew T.

2014-01-01

274

Can sacrificial feeding areas protect aquatic plants from herbivore grazing? Using behavioural ecology to inform wildlife management.  

Science.gov (United States)

Effective wildlife management is needed for conservation, economic and human well-being objectives. However, traditional population control methods are frequently ineffective, unpopular with stakeholders, may affect non-target species, and can be both expensive and impractical to implement. New methods which address these issues and offer effective wildlife management are required. We used an individual-based model to predict the efficacy of a sacrificial feeding area in preventing grazing damage by mute swans (Cygnus olor) to adjacent river vegetation of high conservation and economic value. The accuracy of model predictions was assessed by a comparison with observed field data, whilst prediction robustness was evaluated using a sensitivity analysis. We used repeated simulations to evaluate how the efficacy of the sacrificial feeding area was regulated by (i) food quantity, (ii) food quality, and (iii) the functional response of the forager. Our model gave accurate predictions of aquatic plant biomass, carrying capacity, swan mortality, swan foraging effort, and river use. Our model predicted that increased sacrificial feeding area food quantity and quality would prevent the depletion of aquatic plant biomass by swans. When the functional response for vegetation in the sacrificial feeding area was increased, the food quantity and quality in the sacrificial feeding area required to protect adjacent aquatic plants were reduced. Our study demonstrates how the insights of behavioural ecology can be used to inform wildlife management. The principles that underpin our model predictions are likely to be valid across a range of different resource-consumer interactions, emphasising the generality of our approach to the evaluation of strategies for resolving wildlife management problems. PMID:25077615

Wood, Kevin A; Stillman, Richard A; Daunt, Francis; O'Hare, Matthew T

2014-01-01

275

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

Energy Technology Data Exchange (ETDEWEB)

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.

Hwang, Seon Yong; Jung, Ho Yong [Department of Materials Science and Engineering, Korea University, Seoul, 136-701 (Korea, Republic of); Jeong, Jun-Ho [Nano-Mechanical Systems Research Center, Korea Institute of Machinery and Materials, Yuseong-gu Daejeon, 305-343 (Korea, Republic of); Lee, Heon, E-mail: heonlee@korea.ac.k [Department of Materials Science and Engineering, Korea University, Seoul, 136-701 (Korea, Republic of)

2009-05-29

276

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.

277

Thermotropic layers for flat-plate collectors - A review of various concepts for overheating protection with polymeric materials  

Energy Technology Data Exchange (ETDEWEB)

Within this paper a comprehensive review of the developments of thermotropic hydrogels, thermotropic polymer blends and thermotropic systems with fixed domains for overheating protection purposes is given. In addition, performance properties for thermotropic layers to prevent overheating in solar collectors are defined. The different thermotropic material classes are discussed as to their ability to meet these requirements. The review shows that thermotropic layers developed so far need to be adapted as to switching temperature and long-term stability for applicability in solar thermal collectors. (author)

Resch, Katharina [Polymer Competence Center Leoben GmbH, Roseggerstrasse 12, 8700 Leoben (Austria); Wallner, Gernot M. [Institute of Materials Science and Testing of Plastics, University of Leoben, Franz-Josef Strasse 18, 8700 Leoben (Austria)

2009-01-15

278

Effect of interface layers on phase-change recording material analyzed by hard X-ray photoelectron spectroscopy method  

International Nuclear Information System (INIS)

The influence of interface layers on the chemical and electronic states of a phase-change recording material, GeBiTe (GBT) alloy, used in high-speed rewritable HD DVD media was investigated for the first time by hard-X-ray photoelectron spectroscopy (HX-PES). The binding state of elements for the amorphous state of the phase-change recording film with interface layers is closer to that of the crystalline state than the amorphous film without interface layers. The density of states (DOS) for the valence band of the amorphous state without an interface layer was smaller than that of the crystalline state. The band-edge energy of the amorphous state without an interface layer was lower than that of the crystalline state by about 0.5eV. On the other hand, the DOS and the band-edge energy of the amorphous state of GBT with interface layers were almost the same as those of the crystalline state. This result may lead to almost the same carrier for electrical conduction for the crystalline state as the amorphous state, which is totally unexpected, thus very interesting, because the atomic arrangements should differ from each other. We speculate that these effects are a factor allowing high-speed crystallization. (author)

279

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)

280

Model of superconducting vortices in layered materials for the interpretation of transmission electron microscopy images  

DEFF Research Database (Denmark)

More realistic simulations of the magnetic field and electron optical phase shift associated to pancake vortices in layered high-Tc superconducting specimen require a number of layers larger than 7, the practical upper limit set by the discrete algebraic approach followed so far. This goal can be achieved by resorting to a continuum approximation of the screening layers above and below the one containing the pancake vortex. It is thus possible to increase the number of layers and to investigate more exotic vortex core structures than those represented by the pancakes pinned at tilted columnar defects. In particular it will be shown how recently observed dumbbell-like contrast features in the out-of-focus images of superconducting vortices forming a large angle with the specimen surfaces can be interpreted as due to a kinked structure of the pancakes. © 2004 The American Physical Society

Beleggia, Marco; Pozzi, G.

2004-01-01

 
 
 
 
281

Dislocation filtering in semiconductor superlattices with lattice-matched and lattice-mismatched layer materials  

International Nuclear Information System (INIS)

We investigate the ability of semiconductor superlattices to filter or block threading dislocations by growing and studying structural properties of superlattices composed of alternating layers (--100 A each) of In/sub x/Ga1/sub -//sub x/As and In/sub y/Al1/sub -//sub y/As. These superlattices were grown with x = y corresponding to lattice-matched compositions such that the layers have minimal strain, and xnot =y corresponding to lattice-mismatched compositions such that the layers have large coherent strains. By correlating the number of dislocations observed in optical images of the superlattices, with the amount of layer strain determined by x-ray double diffraction analysis, we investigate the effect of strain on the filtering ability. We find that both types of superlattices are effective in filtering dislocations

282

Powder Synthesis of SrTiO sub 3 Boundary Layer Capacitor Materials.  

Science.gov (United States)

Powders with controlled agglomerate structure were synthesized from a solution of strontium nitrate and titanium citrate to produce strontium titanate boundary layer capacitors (STBLCs). A unique citrate formation ultrasonically generated aerosol/freeze d...

B. A. Tuttle, J. A. Voigt

1987-01-01

283

Conceptual material design for magnetic tunneling junction cap layer for high magnetoresistance ratio  

International Nuclear Information System (INIS)

A conceptual material design for magnetic tunneling junction cap layer realizing a steep NiFe/AlOx interface is proposed. Tunnel magneto resistance stack of cap/NiFe/AlOx/CoFe/Ru/CoFe/PtMn/Ta//sub was prepared. Maximum magnetoresistance (MR) ratios of nonmagnetic-NiFeZr, Zr, Ta, Ru, and Rh caps at 0 V were 55%, 28%, 50%, 43%, and 42%, respectively. The decrease of MR ratio and the increase of resistance area product RA with Ru cap compared to Ta cap correlate with the partial oxidation of the NiFe/AlOx interface occurring in additional postannealing, which was confirmed by focused-ion-beam-transmission-electron-microscope-energy-dispersive- x-ray-fluorescence observation. Since standard electrode potential is Ta< Fe< Ni< Ru, it is supposed that NiFe with Ru cap is positively charged, the NiFe/AlOx interface is easily oxidized during annealing by negatively charged oxidizing species, and increase of RA and decrease of MR ratio occur. RA with Rh cap was even higher than that with Ru cap, consistent with the higher electrode potential of Rh than that of Ru. On the other hand, as the electrode potential of Ta is lower than NiFe, we think that NiFe with Ta cap is negatively charged, the oxidation of the NiFe/AlOx interface is suppressed, and the lower RA and higher MR ratio than those with Ru cap are obtained. Since the electrode potential of Zr is still lower than Ta, we expected an even higher MR ratio with Zr cap. However, magnetism and magnetostriction of Zr/NiFe/AlOx//sub sample changed significantly at first and saturated rapidly in sequential postannealing processes, indicating that the diffusion of Zr to NiFe proceeds at the beginning and saturates promptly. Therefore, we introduced nonmagnetic-NiFeZr alloy cap and the highest MR ratio of 55% was realized, without suffering from the diffusion of Zr. The highest MR ratio with nonmagnetic-NiFeZr cap is consistent with the lowest electrode potential of Zr, and we believe that nonmagnetic-NiFeZr cap realizes a steep NiFe/AlOx interface without the oxidation of NiFe

284

Thin-layer chromatography of radioactively labelled cholesterol and precursors from biological material  

International Nuclear Information System (INIS)

The investigation methods of the action of xenobiotics on sterol biosynthesis from 14C-acetate in rat hepatocyte cultures can be developed, with regard to extraction using Extrelut and the separation of the sterol pattern by thin-layer chromatography, in such a way that they are suitable for wider application, e.g., screening. Good visualisation and recognition of changes in the sterol pattern are possible using autoradiography of the thin-layer chromatogram. (orig.)

285

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

286

Adhesive and stress-strain properties of the polymeric layered materials reinforced by the knitted net  

International Nuclear Information System (INIS)

It is known that the textile materials (woven fabric and mesh) used for reinforcing of various polymer films and coatings. This paper discusses reinforcement of thermoplastic polymers based on PE (polyethylene) and PVC (polyvinyl Chloride) with a knitted mesh weave loin. According by the research identified adhesion, strength and deformation properties of new polymer laminates. The production of such materials has been discussed in detail and performance of resultant composites material is analyzed and compared with other materials. (author)

287

Patterning Technology of Ferrite and Insulating Material in a Single Layer of the Multilayer Ceramic Device  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Patterning technology of ferrite and insulating material in multilayer ceramic devices is proposed. In the conventional technology, the different ceramic materials such as the ferrite and the insulating material have been prepared in the form of the each different green sheet, and then they have been stacked each other. Otherwise the different material has filled cavities that were formed by a mechanical punching in advanced. In our proposing technology, arbitrary patterning of the different ...

Fumio Uchikoba; Ken Saito; Toshiki Fujino; Aki Kenmochi; Minami Takato

2012-01-01

288

Test of Capsule (11M-22K) with Double Layered Thermal Media for Irradiation of Future Nuclear System Materials  

Energy Technology Data Exchange (ETDEWEB)

By the irradiation test, the structural integrity and safety of the capsule during irradiation at high temperature were confirmed. The outlet temperatures of VHTR and SFR are 1,000 .deg. C and 550 .deg. C, respectively, which are much higher than the irradiation temperatures of the material capsules tested at HANARO up to recently. The capsule for high-temperature materials was designed as a double layered thermal media, in which the outer layer is aluminum and the inner layer is Ti or graphite. This capsule aims at allowing irradiation at temperatures of up to 1,000 .deg. C in the near future. As future nuclear systems are to be operated at high temperatures, the irradiation tests at high temperature are necessary. In accordance with this requirement, a capsule suitable for an irradiation test at high temperatures is being developed to overcome a restriction on the use of aluminum at high temperature. A new capsule with thermal media of a double layered structure, the outer of which is Al and the inner is Ti or graphite, was designed. This capsule was applied to an irradiation test up to 900 .deg. C. The capsule for use at the irradiation test up to 1,000 .deg. C will be developed at the beginning in 2014.

Cho, Man Soon; Choo, Kee Nam; Yang, Seong Woo; Kang, Young Hwan; Park, Sang Jun [Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of)

2013-05-15

289

Test of Capsule (11M-22K) with Double Layered Thermal Media for Irradiation of Future Nuclear System Materials  

International Nuclear Information System (INIS)

By the irradiation test, the structural integrity and safety of the capsule during irradiation at high temperature were confirmed. The outlet temperatures of VHTR and SFR are 1,000 .deg. C and 550 .deg. C, respectively, which are much higher than the irradiation temperatures of the material capsules tested at HANARO up to recently. The capsule for high-temperature materials was designed as a double layered thermal media, in which the outer layer is aluminum and the inner layer is Ti or graphite. This capsule aims at allowing irradiation at temperatures of up to 1,000 .deg. C in the near future. As future nuclear systems are to be operated at high temperatures, the irradiation tests at high temperature are necessary. In accordance with this requirement, a capsule suitable for an irradiation test at high temperatures is being developed to overcome a restriction on the use of aluminum at high temperature. A new capsule with thermal media of a double layered structure, the outer of which is Al and the inner is Ti or graphite, was designed. This capsule was applied to an irradiation test up to 900 .deg. C. The capsule for use at the irradiation test up to 1,000 .deg. C will be developed at the beginning in 2014

290

Photo-switching in a hybrid material made of magnetic layered double hydroxides intercalated with azobenzene molecules.  

Science.gov (United States)

A magnetic photoresponsive hybrid material is prepared by intercalation of a switchable trans-azobenzene-4,4'-dicarboxylate guest in the interlamellar space offered by a ferromagnetic Co(2+)Al(3+)-layered double hydroxide (LDH) host. Magnetic switching is triggered by compression/modification of the in-plane structure coupled the guest's isomerization causing a change in the magnetization of 27%. PMID:24706546

Abellán, Gonzalo; Coronado, Eugenio; Martí-Gastaldo, Carlos; Ribera, Antonio; Jordá, Jose Luis; García, Hermenegildo

2014-06-25

291

Modulation transfer function measurements for thin layers of azo dyes in PVA matrix used as an optical recording material.  

Science.gov (United States)

Diffraction efficiencies and characteristic erasure times were measured for two recording materials suitable for real-time holography and four-wave mixing. A study of real-time transmission volume grating formation was done in conjunction with polarization states of the writing beams for 30-microm thick layers. Modulation transfer function curves presented were obtained using a versatile device for which the spatial frequency domain was 500-4000 cycles/mm. PMID:20539385

Couture, J J; Lessard, R A

1988-08-15

292

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

293

Some regularities of structure and surface layer properties changing of metal materials after electro-erosion machining  

International Nuclear Information System (INIS)

Effect of electoerosion machining on the surface state of pearlitic class steel of the 12KhN4MFA type, bronzes BrAMts 9-2 and BrAZhNMts 9-4-4-1, of the alloy PT-3V has been studied. As a result of electroerosion machining (EEM) a transformed layer, presenting overheated and partially melted metal, the structure and hardness of which depend on chemical composition of the materials treated, their tendency to phase transformatins and saturation with introduction elements, is formed on the surface of metal materials

294

Synthesis of nested coaxial multiple-walled nanotubes by atomic layer deposition.  

Science.gov (United States)

Nested multiple-walled coaxial nanotube structures of transition metal oxides, semiconductors, and metals were successfully synthesized by atomic layer deposition (ALD) techniques utilizing nanoporous anodic aluminum oxide (AAO) as templates. In order to fabricate free-standing tube-in-tube nanostructures, successive ALD nanotubes were grown on the interior template walls of the AAO nanochannels. The coaxial nanotubes were alternated by sacrificial spacers of ALD Al(2)O(3), to be chemically removed to release the nanotubes from the AAO template. In this study, we synthesized a novel nanostructure with up to five nested coaxial nanotubes within AAO templates. This synthesis can be extended to fabricate n-times tube-in-tube nanostructures of different materials with applications in multisensors, broadband detectors, nanocapacitors, and photovoltaic cells. PMID:20085347

Gu, Diefeng; Baumgart, Helmut; Abdel-Fattah, Tarek M; Namkoong, Gon

2010-02-23

295

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

296

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

Science.gov (United States)

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.

2014-09-01

297

Diffusivity measurements of silicon in silicon dioxide layers using isotopically pure material  

International Nuclear Information System (INIS)

We report measurement of the silicon diffusion coefficient in silicon dioxide films using isotopically enriched 28Si silicon dioxide layers that enable relatively low 30Si concentration measurements to be performed using secondary ion mass spectrometry. Two types of experiments are made. 30Si atoms are introduced in excess in a stoichiometric isotopically pure silicon dioxide layer either by ion implantation or by a predeposition technique. These experiments are representative of any physical situation in which excess silicon atoms are introduced into silicon dioxide layers during silicon processing. The estimated diffusivity values are significantly higher than previously reported values for Si diffusion within a stoichiometric oxide and closer to reported values for excess Si diffusion within an oxide. The activation energy of the diffusivity is found to be 4.74 eV. [copyright] 2001 American Institute of Physics

298

Thin layer chromatography-application in qualitative analysis on presence of coumarins and flavonoids in plant material.  

Science.gov (United States)

Drugs, natural medicinal plant, animals and mineral materials, have a large and various application in official pharmacy and medicine. Carriers of multilateral pharmacological effects that those drugs shown, are chemically define as active components that are present in them. Methods of qualitative and quantitative analysis are used for the chemical investigation of components that drugs contain. Method of thin layer chromatography has been shown as very reliable. According to the chemical investigation of single drugs, it is possible to define a group of compound or single compound comparing them with standards. Relating to the usage of method of thin layer chromatography, it has been carried out investigation on presence of coumarins and flavonoids in domestic plant material that have wide everyday usage. Coumarins and flavonoids from the point of view of chemical belonging are phenol derivatives with important pharmacological effects. Applying method of thin layer chromatography, it is detected presence of coumarins and flavonoids substances in plant material that has been tested. Anethi graveolens fructus et folium (fruit and leaf of dill), Anethum graveolens L., Apiaceae, Avenae sativae fructus (fruit of oats), Avena sativa L., Poaceae and Asperulae odoratae herba (sweet woodruff), Asperula odorata L., Rubiaceae. Chromatograms are developed in systems cyclohexane-ethylacetat (13:7) and toluene-ether (1:1) saturated with 10% acetic acid, and visualisation by observing on UV lamp (254 and 366 nm), spraying with reagents KOH (10% ethanol solution) and diphenylboryloxyethylamine (1% methanol solution). PMID:16232145

Kovac-Besovi?, Elvira E; Duri?, Kemal

2003-07-01

299

Surface wave propagation in a swelling porous elastic material under a inviscid liquid layer  

Directory of Open Access Journals (Sweden)

Full Text Available The present investigation is to study the surface wave propagationin a swelling porous elastic half space under homogeneous inviscidliquid layer. The frequency equation is derive for both swellingporous (SP and without swelling porous (elastic medium (EL medium. The dispersion curves giving the phase velocity and attenuation coefficient with wave number are plotted graphically to depict the effect of swelling porous half space under a homogeneous inviscid liquid layer. The amplitudes of displacement in both SP and EL medium are obtained and are shown graphically. Some special cases are also deduced from the present investigation.

Kuldeep Kumar

2010-12-01

300

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

 
 
 
 
301

Ab initio synthesis of single-layer III-V materials  

Science.gov (United States)

The discovery of a novel material requires the identification of the material's composition as well as of suitable synthesis conditions. We present a data-mining approach to identify suitable substrates for the growth of two-dimensional materials and apply the method to the recently predicted two-dimensional III-V compounds. We identify several lattice-matched substrates for their epitaxial growth, stabilization, and functionalization. Density-functional calculations show that these substrates sufficiently reduce the formation energies of the metastable two-dimensional materials to make them thermodynamically stable. We show that chemical interactions of the two-dimensional materials with the substrates shift the Fermi level of these materials, resulting in doping. The large adsorption energies and strong doping indicate that these metals should provide good electrical contact to enable transport measurements and electronic applications.

Singh, Arunima K.; Zhuang, Houlong L.; Hennig, Richard G.

2014-06-01

302

Controllable fabrication of nanostructured materials for photoelectrochemical water splitting via atomic layer deposition.  

Science.gov (United States)

Photoelectrochemical (PEC) water splitting is an attractive approach to generate hydrogen as a clean chemical fuel from solar energy. But there remain many fundamental issues to be solved, including inadequate photon absorption, short carrier diffusion length, surface recombination, vulnerability to photo-corrosion, and unfavorable reaction kinetics. Owing to its self-limiting surface reaction mechanism, atomic layer deposition (ALD) is capable of depositing thin films in a highly controllable manner, which makes it an enabling technique to overcome some of the key challenges confronted by PEC water splitting. This tutorial review describes some unique and representative applications of ALD in fabricating high performance PEC electrodes with various nanostructures, including (i) coating conformal thin films on three-dimensional scaffolds to facilitate the separation and migration of photocarriers and enhance light trapping, as well as realizing controllable doping for bandgap engineering and forming homojunctions for carrier separation; (ii) achieving surface modification through deposition of anti-corrosion layers, surface state passivation layers, and surface catalytic layers; and (iii) identifying the main rate limiting steps with model electrodes with highly defined thickness, composition, and interfacial structure. PMID:24500041

Wang, Tuo; Luo, Zhibin; Li, Chengcheng; Gong, Jinlong

2014-10-20

303

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

Energy Technology Data Exchange (ETDEWEB)

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.

Yanguas-Gil, Angel; Elam, Jeffrey W., E-mail: jelam@anl.gov [Argonne National Laboratory, Energy Systems Division, 9700 S Cass Ave, Lemont, Illinois 60439 (United States)

2014-05-15

304

Morphology change of galvanically displaced one-dimensional tellurium nanostructures via controlling the microstructure of sacrificial Ni thin films  

International Nuclear Information System (INIS)

One-dimensional Tellurium (Te) nanostructures with controlled dimensions and morphologies have been synthesized by the galvanic displacement reaction (GDR) of electrodeposited nickel (Ni) thin films. The effects of sacrificial Ni microstructure and HTeO2+ ion concentration on the resulting Te nanostructures were systematically investigated. The preferred crystal orientation of sacrificial Ni thin films was varied to synthesize Te nanostructures with various levels of distinctiveness. By adjusting the concentration of HTeO2+ ions in the galvanic displacement electrolyte, well-aligned one-dimensional (1-D) Te nanostructures such as conical and hexagonal pillars were prepared where the diameter ranged from ?70 to ?900 nm and the length ranged from 1 to 3.6 ?m

305

Effects of cyclical environments on high-performance multi-layer insulation materials.  

Science.gov (United States)

Results of a test program designed to determine the effects of 100 temperature and compressive loading cycles on several multilayer insulation materials and composites. A total of four reflector materials, four separator materials, eight face-sheet systems, and one fastener material were subjected to 100 temperature cycles from -320 to 400 or 650 F. Generic types of materials studied included Mylar, Kapton, Dacron, Nomex, and Beta Glass. The temperature cycling was followed by visual inspection, metal adhesion tests on the reflectors, and tensile tests of the face sheets, fastener, and separators. A total of six composites were subjected to compressive cycles between zero and 0.15 psi, and density changes were measured. Application of the experimental results to the shuttle orbiter is discussed.

Krause, D. R.; Fredrickson, G. O.; Klevatt, P. L.

1971-01-01

306

Thermal decomposition pathway of undoped and doped zinc layered gallate nanohybrid with Fe 3+, Co 2+ and Ni 2+ to produce mesoporous and high pore volume carbon material  

Science.gov (United States)

A series of brucite-like materials, undoped and doped zinc layered hydroxide nitrate with 2% (molar) Fe 3+, Co 2+ and Ni 2+ were synthesized. Organic-inorganic nanohybrid material with gallate anion as a guest, and zinc hydroxide nitrate, as an inorganic layered host was prepared by the ion-exchange method. The nanohybrid materials were heat-treated at various temperatures, 400-700 °C. X-ray diffraction, thermal analysis and also Fourier transform infrared results showed that incorporation of the doping agents within the zinc layered hydroxide salt layers has enhanced the heat-resistivity of the nanohybrid materials in the thermal decomposition pathway. Porous carbon materials can be obtained from the heat-treating the nanohybrids at 600 and 700 °C. Calcination of the nanohybrids at 700 °C under nitrogen atmosphere produces mesoporous and high pore volume carbon materials.

Ghotbi, Mohammad Yeganeh; bin Hussein, Mohd Zobir; Yahaya, Asmah Hj; Abd Rahman, Mohd Zaki

2009-12-01

307

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’ (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

308

Fabrication of Porous Hydroxyapatite through Combination of Sacrificial Template and Direct Foaming Techniques  

Directory of Open Access Journals (Sweden)

Full Text Available The porous hydroxyapatite (HA bioceramics were prepared through combination of sacrificial template and direct foaming techniques using PMMA granules (varied from 5 to 50wt% in content as a template and H2O2 solution (varied from 5 to 30wt% in concentration as a foaming agent, respectively. The effects of PMMA content and H2O2 concentration on final porosity, microstructure and mechanical strengths were studied. The porous samples using PMMA provided the porosity ranging from 52% to 75%, the samples using H2O2 had the porosity ranging from 82% to 85%, and the sample using both pore formers provided the porosity ranging between 84% and 90%. The higher content of PMMA and concentration of H2O2 led the porosity increased, leading to a decrease in the compressive and flexural strengths. Furthermore, this combination technique allowed interconnected pores having two levels of pore size, which were come from PMMA and H2O2. The PMMA formed the small pores with the diameter ranging between 100 and 300 ?m, while H2O2 provided the larger pores with the diameter ranging from 100 to 1,000 ?m depending on concentration.

Serena M Best

2011-04-01

309

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.

310

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.

311

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

312

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)

313

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.

314

Hydrogen isotopes confinement in the over-dusted layers of fusion reactor candidate materials  

International Nuclear Information System (INIS)

In the work the experiments on gas-emission determination from samples of sputtered beryllium, graphite, tungsten, jointly sputtered graphite and tungsten obtained by the magnetron sputtering method at the 'Argamak' facility (National Nuclear Center of the Republic of Kazakhstan), as well as the samples processed on the 'OSPA' plasma accelerator (TRINITI, Russia). The gas-release curves were obtained for indicated samples under different heating velocities within temperature range from 300 up to 1200 K. Gas-release parameters and hydrogen isotopes confinement in these layers were determined. Simulation of hydrogen isotopes gas-emission from samples sputtered layers on the base of obtained experiments with application of simulating programs and TMAP code was carried out

315

Mass exchange in adjacent layers of grain material stored in silo  

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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

316

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

International Nuclear Information System (INIS)

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)

317

Deuterium retention in codeposited layers and carbon materials exposed to high flux D-plasma  

Science.gov (United States)

A ceramic BCN target with samples of dense RG-Ti-91 without boron, RG-Ti-B with boron (0.1 at.%) and porous POCO AXF-5Q graphites was exposed in a stationary D-plasma of the `Lenta' device with an ion energy of 200 eV and an ion flux of (3 - 6) × 10 17 D/cm 2s at 1040 and 1400 K to a fluence of ˜1 × 10 22 D/cm 2. Codeposited layers were obtained for comparison on the target surface. Thermal desorption spectroscopy (TDS) showed that the amount of deuterium in RG-Ti after exposure at 1040 K was more than an order of magnitude higher than in POCO (9 × 10 17 and 7 × 10 16 D/cm 2, respectively). The retention took place preferentially in a surface layer about 100 ?m thick. The bulk deuterium concentration in both RG-Ti and POCO was lower than 1 appm. The irradiated RG-Ti surface was subjected to strong erosion and consisted of `columnar' grains covered with TiC at their tips. The deuterium in RG-Ti irradiated at 1400 K was located in the surface layer (1.5 × 10 16 D/cm 2). The value of the bulk concentration did not exceed 0.1 appm while in POCO it was equal to about 20 appm. TDS for deuterium in RG-Ti demonstrated a spectrum similar to that for codeposited layers on a target surface. The differences in deuterium retention in the graphites are explained on the basis of structural differences. Considering tritium inventory assessment for ITER, dense graphites like RG-Ti are preferred for working divertor plates at high temperatures.

Arkhipov, I. I.; Gorodetsky, A. E.; Zalavutdinov, R. Kh; Zakharov, A. P.; Burtseva, T. A.; Mazul, I. V.; Khripunov, B. I.; Shapkin, V. V.; Petrov, V. B.

318

High-Efficiency White Organic Light-Emitting Diodes Using Codoped Blue-Light-Emitting Layers with Different Functional Materials  

Science.gov (United States)

We have demonstrated high-efficiency white organic light-emitting diodes (WOLEDs) using codoped blue-emitting layers with three light emitters, 4''-(2,2-diphenylvinyl)-1-[4-(N,N-diphenylamino)-styryl]-terphenyl, fac-tris(2-phenypyridine) iridium(III), and bis(5-benzoyl-2-phenylpyridinato-C,N)iridium(III) (acetylacetonate). Blue-emitting layers (BEMLs) were codoped with the different functional materials, N,N'-bis(1-naphyl)-N,N'-diphenyl-1,1'-biphenyl-4,4'-diamine and 4,7-diphenyl-1,10-phenanthroline, which are used as charge-transporting materials in OLEDs. An optimized device with centralized carriers in emitting layers showed a maximum luminance of 19 710 cd/m2 at 12 V, a maximum luminous efficiency of 23.20 cd/A at 0.14 mA/cm2, and an external quantum efficiency of 10.20% at 32.19 cd/m2.

Seo, Ji Hoon; Kim, Gu Young; Koo, Ja Ryong; Hyung, Gun Woo; Lee, Kum Hee; Kim, Jin Ho; Yoon, Seung Soo; Kim, Young Kwan

2009-05-01

319

Experiments on passive hypersonic boundary layer control using ultrasonically absorptive carbon-carbon material with random microstructure  

Science.gov (United States)

For the first time, the influence of ultrasonically absorptive carbon-carbon material on hypersonic laminar to turbulent boundary layer transition was investigated experimentally. A 7° half-angle blunted cone with a nose radius of 2.5 mm and a total length of 1,077 mm was tested at zero angle of attack in the High Enthalpy Shock Tunnel Göttingen of the German Aerospace Center (DLR) at Mach 7.5. One-third of the metallic model surface in circumferential direction was replaced by DLR in-house manufactured ultrasonically absorptive carbon-carbon material with random microstructure for passive transition control. The remaining model surface consisted of polished steel and served as reference surface. The model was equipped with coaxial thermocouples to determine the transition location by means of surface heat flux distribution. Flush-mounted piezoelectric fast-response pressure transducers were used to measure the pressure fluctuations in the boundary layer associated with second-mode instabilities. The free-stream unit Reynolds number was varied over a range of Re m = 1.5 × 106 m-1 to Re m = 6.4 × 106 m-1 at a stagnation enthalpy of h 0 ? 3.2 MJ/kg and a wall temperature ratio of T w/ T 0 ? 0.1. The present study revealed a clear damping of the second-mode instabilities and a delay of boundary layer transition along the ultrasonically absorptive carbon-carbon insert.

Wagner, Alexander; Kuhn, Markus; Martinez Schramm, Jan; Hannemann, Klaus

2013-10-01

320

High performance LiMn2O4 cathode materials grown with epitaxial layered nanostructure for Li-ion batteries.  

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Tremendous research works have been done to develop better cathode materials for a large scale battery to be used for electric vehicles (EVs). Spinel LiMn2O4 has been considered as the most promising cathode among the many candidates due to its advantages of high thermal stability, low cost, abundance, and environmental affinity. However, it still suffers from the surface dissolution of manganese in the electrolyte at elevated temperature, especially above 60 °C, which leads to a severe capacity fading. To overcome this barrier, we here report an imaginative material design; a novel heterostructure LiMn2O4 with epitaxially grown layered (R3?m) surface phase. No defect was observed at the interface between the host spinel and layered surface phase, which provides an efficient path for the ionic and electronic mobility. In addition, the layered surface phase protects the host spinel from being directly exposed to the highly active electrolyte at 60 °C. The unique characteristics of the heterostructure LiMn2O4 phase exhibited a discharge capacity of 123 mAh g(-1) and retained 85% of its initial capacity at the elevated temperature (60 °C) after 100 cycles. PMID:24392731

Lee, Min-Joon; Lee, Sanghan; Oh, Pilgun; Kim, Youngsik; Cho, Jaephil

2014-02-12

 
 
 
 
321

Sugar-anionic clay composite materials: intercalation of pentoses in layered double hydroxide  

Science.gov (United States)

The intercalation of non-ionized guest pentoses (ribose and 2-deoxyribose) into the Mg-Al and Zn-Al layered double hydroxides (LDHs) was carried out at 298 K by the calcination-rehydration reaction using the Mg-Al and Zn-Al oxide precursors calcined at 773 K. The resulting solid products reconstructed the LDH structure with incorporating pentoses, and the maximum amount of ribose intercalated by the Mg-Al oxide precursor was approximately 20 times that by the Zn-Al oxide precursor. The ribose/Mg-Al LDH was observed to have the expanded LDH structure with a broad (003) spacing of 0.85 nm. As the thickness of the LDH hydroxide basal layer is 0.48 nm, the interlayer distance of the ribose/Mg-Al LDH is 0.37 nm. This value corresponds to molecular size of ribose in thickness (0.36 nm), supporting that ribose is horizontally oriented in the interlayer space of LDH. The maximum amount of ribose intercalated by the Mg-Al oxide precursor was approximately 5 times that of 2-deoxyribose. Ribose is substituted only by the hydroxyl group at C-2 position for 2-deoxyribose. Therefore, the number of hydroxyl group of sugar is essentially important for the intercalation of sugar molecule into the LDH, suggesting that the intercalation behavior of sugar for the LDH was greatly influenced by hydrogen bond between hydroxyl group of the intercalated pentose and the LDH hydroxide basal layers.

Aisawa, Sumio; Hirahara, Hidetoshi; Ishiyama, Kayoko; Ogasawara, Wataru; Umetsu, Yoshio; Narita, Eiichi

2003-09-01

322

Preparation and Characterization of TiO2/CdS Layers as Potential Photoelectrocatalytic Materials  

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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

323

Acid modified diatomaceous earth--a sorbent material for thin layer chromatography.  

Science.gov (United States)

Natural diatomaceous earth (DE) is modified by flux calcination and refluxing with acid. To characterize natural DE, modified DE's [flux calcinated (FC)DE and FCDE-I] and silica gel 60GF(254) (Si-60GF(254)) are analyzed microscopically, physically, and chemically by various techniques. FCDE-I and Si-60GF(254) are investigated for their usefulness in the stationary phase of thin layer chromatography (TLC) both individually and in composition. Sodium diethyldithiocarbamate (DEDTC) and ammonium pyrrolidinedithiocarbamate (PyDTC) are prepared as Co or Cu (M) complexes [M(DEDTC)(2) and M(PyDTC)(2), respectively]. These complexes and their mixtures are run on thin layers of Si-60GF(254) and FCDE-I individually, and on various FCDE-I and Si-60GF(254) mixtures. Pure toluene and various toluene-cyclohexane mixtures (3:1, 1:1, 1:2, 1:3, v/v) are used as mobile phases for the running the complexes. The best analytical separations of both M(DEDTC)(2) and M(PyDTC)(2) complexes are obtained when using pure toluene and toluene-cyclohexane (3:1, 1:1, v/v) as mobile phases on FCDE-I-Si-60GF(254) (1:3, 1:1, w/w) layers as stationary phases. This study shows that it is possible to qualitatively analyze and to satisfactorily separate a mixture Cu(2+) and Co(2+) cations on cited chromatographic systems. PMID:18402721

Ergül, Soner; Sava?ci, Sahin

2008-04-01

324

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

325

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

Science.gov (United States)

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.

George, Johnsy; Kumar, R.; Sajeevkumar, V. A.; Sabapathy, S. N.; Vaijapurkar, S. G.; Kumar, D.; Kchawahha, A.; Bawa, A. S.

2007-07-01

326

Long-term self-assembly of inorganic layered materials influenced by the local states of the interlayer cations.  

Science.gov (United States)

A wide variety of parameters as, e.g., temperature, humidity, particle size, and cation state are known to influence the agglomeration process of two-dimensional (2D) nanosheets, called self-assembly, in inorganic layered materials. The detailed studies on which parameters are decisive and how they influence the self-assembly, however, have not been performed yet. Here, the long-term self-assembly was studied for layered stevensite and hectorite, and compared with our previous data of saponite for elucidating an influence of local states of the interlayer cations. The results were analyzed with respect to a recently established rheological model, in which 2D nanosheets migrate parallel to the layer direction aided by water molecules as lubricants [K. Sato et al., J. Phys. Chem. C, 2012, 116, 22954]. With decreasing the strength of the local electric fields facing to the interlayer spaces, cation positions split into two or three, which makes the distribution of water molecules more uniformly. These water molecules enhance the rheological motion of the 2D nanosheets parallel to the layer direction, thus accelerating the self-assembly process. PMID:24770790

Sato, Kiminori; Numata, Kazuomi; Dai, Weili; Hunger, Michael

2014-06-14

327

Analytical and modeling investigations of volume fraction of interfacial layers around ellipsoidal aggregate particles in multiphase materials  

International Nuclear Information System (INIS)

The determination of the volume fraction of interfacial layers is very significant for assessing the quantitative relationship between the microstructure and macroscopic physical properties of complex multiphase materials. In this work, based on a three-phase composite structure, an approximate analytical model for the volume fraction of interfacial layers around ellipsoidal aggregate particles is presented in detail. To verify the accuracy and reliability of the derived analytical model, a numerical model is introduced by means of random packing of polydispersed ellipsoidal aggregate particles, in which the relative spatial position between an arbitrary point and an ellipsoidal particle is precisely and conveniently determined. With the analytical and numerical models applied, the dependence of the volume fraction of interfacial layers on various factors, such as the particle shape, the volume fraction and the maximum particle size of aggregates, and the thickness of the interfacial layers, is evaluated. Furthermore, the results from the analytical model and the numerical model with these factors are compared. It is found that the theoretical results are favorably consistent with the simulated results. (paper)

328

Triple-conducting layered perovskites as cathode materials for proton-conducting solid oxide fuel cells.  

Science.gov (United States)

We report on an excellent anode-supported H(+) -SOFC material system using a triple conducting (H(+) /O(2-) /e(-) ) oxide (TCO) as a cathode material for H(+) -SOFCs. Generally, mixed ionic (O(2-) ) and electronic conductors (MIECs) have been selected as the cathode material of H(+) -SOFCs. In an H(+) -SOFC system, however, MIEC cathodes limit the electrochemically active sites to the interface between the proton conducting electrolyte and the cathode. New approaches to the tailoring of cathode materials for H(+) -SOFCs should therefore be considered. TCOs can effectively extend the electrochemically active sites from the interface between the cathode and the electrolyte to the entire surface of the cathode. The electrochemical performance of NBSCF/BZCYYb/BZCYYb-NiO shows excellent long term stability for 500 h at 1023 K with high power density of 1.61 W?cm(-2) . PMID:25146887

Kim, Junyoung; Sengodan, Sivaprakash; Kwon, Goeun; Ding, Dong; Shin, Jeeyoung; Liu, Meilin; Kim, Guntae

2014-10-01

329

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

330

Molecular Sensing Ability of Layered Inorganic/Luminous Organic Nano Hybrid Solid Materials  

International Nuclear Information System (INIS)

To apply titanate nanosheet/decyltrimethlammonium/rhodamine 3B (TNS/C10TMA/R3B) hybrid material with highly luminescent ability to high performance sensor or indicator, spectroscopic properties in the absence and presence of water and/or NH3 vapors were investigated. The TNS/C10TMA/R3B hybrid material exhibited tone change of photoadsorption and photoluminescence in the presence of water vapor. Moreover, this material exhibited remarkable quenching in the presence of NH3 vapor under humid condition. It was found that this quenching was caused by an intramolecular cyclization reaction of incorporated R3B. This photoluminescence intensity decreased with an increase in NH3 concentration. This fact is that the present hybrid material has a high potential for molecular sensor or indicator.

331

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

332

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.

333

Hierarchical assembly of Ti(IV)/Sn(II) co-doped SnO? nanosheets along sacrificial titanate nanowires: synthesis, characterization and electrochemical properties.  

Science.gov (United States)

Hierarchical assembly of Ti(IV)/Sn(II)-doped SnO? nanosheets along titanate nanowires serving as both sacrificial templates and a Ti(IV) source is demonstrated, using SnCl2 as a tin precursor and Sn(II) dopants and NaF as the morphology controlling agent. Excess fluoride inhibits the hydrolysis of SnCl2, promoting heterogeneous nucleation of Sn(II)-doped SnO? on the titanate nanowires due to the insufficient oxidization of Sn(II) to Sn(IV). Simultaneously, titanate nanowires are dissolved forming Ti(4+) species under the etching effect of in situ generated HF resulting in spontaneous Ti(4+) ion doping of SnO? nanosheets formed under hydrothermal conditions. Compositional analysis indicates that Ti(4+) ions are incorporated by substitution of Sn sites at a high level (16-18 at.%), with uniform distribution and no phase separation. Mössbauer spectroscopy quantified the relative content of Sn(II) and Sn(IV) in both Sn(II)-doped and Ti(IV)/Sn(II) co-doped SnO? samples. Electrochemical properties were investigated as an anode material in lithium ion batteries, demonstrating that Ti-doped SnO? nanosheets show improved cycle performance, which is attributed to the alleviation of inherent volume expansion of the SnO?-based anode materials by substituting part of Sn sites with Ti dopants. PMID:23904051

Wang, Hongkang; Xi, Liujiang; Tucek, Jiri; Zhan, Yawen; Hung, Tak Fu; Kershaw, Stephen V; Zboril, Radek; Chung, C Y; Rogach, Andrey L

2013-10-01

334

Ultrathin spinel membrane-encapsulated layered lithium-rich cathode material for advanced Li-ion batteries.  

Science.gov (United States)

Lack of high-performance cathode materials has become a technological bottleneck for the commercial development of advanced Li-ion batteries. We have proposed a biomimetic design and versatile synthesis of ultrathin spinel membrane-encapsulated layered lithium-rich cathode, a modification by nanocoating. The ultrathin spinel membrane is attributed to the superior high reversible capacity (over 290 mAh g(-1)), outstanding rate capability, and excellent cycling ability of this cathode, and even the stubborn illnesses of the layered lithium-rich cathode, such as voltage decay and thermal instability, are found to be relieved as well. This cathode is feasible to construct high-energy and high-power Li-ion batteries. PMID:24844948

Wu, Feng; Li, Ning; Su, Yuefeng; Zhang, Linjing; Bao, Liying; Wang, Jing; Chen, Lai; Zheng, Yu; Dai, Liqin; Peng, Jingyuan; Chen, Shi

2014-06-11

335

Toward Nanoscale Material Applications: Colloidal Quantum Dot Memory And Multi-Layer Graphene Electronics And Optoelectronics  

Science.gov (United States)

In this dissertation, the analysis of a possible use of colloidal semiconductor quantum dots (QDs) in memory storage devices is presented. The charging and discharging behaviors of capped cadmium selenide (CdSe) QDs deposited on a sheet of graphite film layers in ambient conditions were analyzed. Individual QDs can be addressed (charged) with the synergistic action of light and the mechanical interaction of a probe of an atomic force microscope (AFM). The probe squeezes the coating layer of QDs helping the photoelectron to tunnel to either the conductive AFM probe or to the substrate. The charge can be induced on individual QDs by locating the QDs with AFM. The charges were stable in ambient conditions (survived up to 24 hours), and even recovered within a minute after their forced neutralization by airflow of negative ions. The analyzed QDs allow recording information at a density up to 1Tb/cm 2. A possibility to attain charging (writing) time down to nanoseconds while keeping discharging (storage) times for more than 100 years is also demonstrated. These results may also be of interest for QDs based sensors, memory, and solar cell applications. Multi-layer heteroepitaxial graphene was successfully formed on 3C-SiC grown on a Si substrate using single gas source molecular beam epitaxy (MBE). The observation of ambipolar behavior, one of the unique properties of graphene, verifies the successful growth of graphene layers. The epitaxial graphene is believed to be unintentionally p-type doped with the Fermi level offset around +0.11˜+0.12 V at the Dirac point. Backgate field-effect transistors using multilayer graphene channel were designed, fabricated and characterized for electronic and optoelectronic applications. Even though some gate leakage current was observed, the experimental results show the device worked as an n-type transistor as well as an infrared detector. The drain saturated current of the graphene channel transistor is on the order of mA/mm. The extracted effective mobility was calculated to be around 6000 cm/ V.s which is much higher than Si under any circumstances. The photoreponsivity of the device was achieved up to 100 A/W at 1064 nm wavelength source. Constant photocurrent from 1400 nm to 1600 nm due to interband transition was also observed. The response at 1.6 THz with photoresponsivity of 75 muA/W at 1.6 THz is believed due to intraband transitions.

Olac-vaw, Roman

336

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

337

Characterization of sputtered indium tin oxide layers as transparent contact material  

International Nuclear Information System (INIS)

The electrical, optical, and various mechanical properties of rf sputtered indium tin oxide layers were investigated in terms of electrical resistivity (four-probe measurement and Hall), optical transparency, scanning transmission electron spectroscopy and x-ray spectroscopy. Whereas the specific conductivity is at the lower limit reported in the literature (2x10-4 ? cm), and the optical transparency is as high as 90% in the wavelength range between 550 and 800 nm, the grain size is between 10 and 25 nm. The stress is tensile and in the range of 7 kbar after deposition, to drop to 3 kbar after anneal

338

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

339

Transport properties of Layer-Antiferromagnet CuCrS2: A possible thermoelectric material  

Digital Repository Infrastructure Vision for European Research (DRIVER)

The electrical, thermal conductivity and Seebeck coefficient of the quenched, annealed and slowly cooled phases of the layer compound CuCrS2 have been reported between 15K to 300K. We also confirm the antiferromagnetic transition at 40K in them by our magnetic measurements between 2K and 300K. The crystal flakes show a minimum around 100K in their in-plane resistance behavior. For the polycrystalline pellets the resistivity depends on their flaky texture and it attains at mo...

Tewari, G. C.; Tripathi, T. S.; Rastogi, A. K.

2009-01-01

340

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

 
 
 
 
341

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

342

Comparative researches concerning cleaning chosen construction materials surface layer using UV and IR laser radiation  

International Nuclear Information System (INIS)

The paper presents comparative research studies of cleaning out of deposits and pollution disposals on different constructional materials like; steel, cast iron, aluminium, copper by using UV and IR laser radiation of wavelength ? =1.064 ?m; ? = 0.532 ?m; ? = 0.355 ?m and ? = 0.266 ?m and also impulse laser TEA CO2 at radiation ? = 10.6 ?m were used for the experiments. Achieved experimental results gave us basic information on parameters and conditions and application of each used radiation wavelength. Each kind of pollution and base material should be individually treated, selecting the length of wave and radiation energy density. Laser microtreatment allows for broad cleaning application of the surface of constructional materials as well as may be used in future during manufacturing processes as: preparation of surface for PVD technology, galvanotechnics, cleaning of the surface of machine parts etc. (author)

343

Collision of a vortex ring on granular material. Part II. Erosion of the granular layer  

International Nuclear Information System (INIS)

In our previous paper (part I), an experimental result was presented on the normal impact of a vortex ring on the granular layer (glass beads of diameter 0.10 mm), which was placed at a specified distance from the outlet of the vortex ring generator. The Reynolds number of the vortex ring ranged from 1000 to 6000, whereas the traveling distance ranged from 2 to 13 times of the diameter of the vortex ring generator nozzle. In part I, the deformation of the vortex ring impacting on the granular layer and the development of the secondary vortex ring were focused. In this paper (part II), the erosion of the granular surface by the vortex ring is described. Various patterns were found depending on the Reynolds number of the vortex ring and the traveling distance. Two patterns, one (grooves) which has radial striations from the central depressed region to the outer edge of the rim and the other (dimples) which is characterized by isolated small depressions around the outer edge of the rim, are examined in detail. The formation processes of these patterns are elucidated in terms of the deformation of the vortex ring. (paper)

344

Study of surfaces and surface layers on high temperature materials after short-time thermal loads  

International Nuclear Information System (INIS)

Being part of the plasma-wall interaction during TOKAMAK operation, erosion- and redeposition processes of First Wall materials substantially influence plasma parameters as well as the properties of the First Wall. An important redeposition process of eroded material is the formation of thin films by atomic condensation. Examinations of First Wall components after TOKAMAK operation lead to the assumption that these thin metallic films tend to agglomerate to small particles under subsequent heat load. In laboratory experiments it is shown that thin metallic films on various substrates can agglomerate under short time high heat fluxes and also under longer lasting lower thermal loads, thus verifying the ''agglomeration hypothesis''. (orig.)

345

A green synthesis of a layered titanate, potassium lithium titanate; lower temperature solid-state reaction and improved materials performance  

Science.gov (United States)

A layered titanate, potassium lithium titanate, with the size range from 0.1 to 30 ?m 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.

Ogawa, Makoto; Morita, Masashi; Igarashi, Shota; Sato, Soh

2013-10-01

346

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)

347

Diseño de aleaciones para ánodos de sacrificio sustentables / Designing alloys for sustainable sacrificial anodes  

Scientific Electronic Library Online (English)

Full Text Available SciELO Mexico | Language: Spanish Abstract in spanish Se presenta: un proceso de diseño de aleaciones para fabricar ánodos de sacrificio, usados en ambientes marinos; la propuesta de sustituir al In con Ag, en aleaciones Al-Zn-In, buscando sustentar el medio ambiente; y la proposición de incluir los parámetros de los procesos de fabricación de ánodos y [...] los estructurales en la normatividad sobre ánodos de sacrificio. Se manufacturaron en el laboratorio, se ensayaron y compararon ocho aleaciones Al-Zn 2% (contenido menor al que señala la norma para aleaciones con In (de 3.5 a 5%) y con Sn (de 4 a 5%), buscando mayor sustentabilidad); cuatro se alearon con In (de 0.59 a 0.766%) y cuatro con Ag (de 0.23 a 0.428%). Se usaron dos rapideces de enfriamiento durante la solidificación, buscando modificar la estructura y cambiar propiedades y comportamientos ante la corrosión -el potencial de corrosión, la rapidez de corrosión, la activación del ánodo, el tipo de corrosión y la eficiencia de corriente-. se evaluaron las estructuras y se midieron sus potenciales; se encontró que la variación de la rapidez de enfriamiento modificó la estructura de las aleaciones, sus propiedades y comportamientos ante la corrosión y que el comportamiento general de algunas de las aleaciones con Ag es superior a las que contienen in. Las mayores eficiencias se dieron en las aleaciones con menor contenido de In (69%) y de Ag (71%). Abstract in english In this paper we present: a) a design process for manufacturing alloys to be used as sacrificial anodes in marine environments; b) the proposal to replace in with Ag, in search of alloys that could contribute to environmental sustain; and c) the proposal to include the parameters related to anode st [...] ructure and their manufacturing process in the regulation of sacrificial anodes. Eight Al-Zn 2% alloys were manufactured, tested, and compared in our laboratory. These had a lower content than the one indicated by the alloy standards - 3.5-5% and 4-5% content for in and Sn respectively- looking for a more sustainable environment. Four of them were alloyed with In (from 0.59 to 0.766%), and four with Ag (from 0.23 to 0.428%). in order to modify the structure, two cooling rates were used during solidification, seeking to modify their properties, and hence their behavior against corrosion, i.e. corrosion potential, corrosion rate, anode activation, type of corrosion and current efficiency. It was found that the variation of the cooling rate changes the structure of the alloys, their properties and corrosion behaviors. The overall behavior of some of the Ag alloys is superior to those containing In. The higher efficiencies were obtained for alloys with the lower amount of In (69%) and Ag (71%).

Guillermo, Salas-Banuet; Laura, Verduzco-Flores.

2013-06-01

348

Two Layer Magnetodielectric Metamaterial with Enhanced Dielectric Constant as a New Ferrite Like Material  

Science.gov (United States)

In this study, we present large enhancement of effective dielectric constant of magnetodielectric metamaterials made from two layers of parallel periodic non-magnetized iron wires embedded inside dielectric (wax), in two orientations of them, relative to the incident electromagnetic field. This kind of enhancement is predicted by finite difference time domain (FDTD) method electromagnetic simulations made for infinite size metamaterials of same unit cell and same electromagnetic wave’s geometry of incidence. In this model, the complex internal constants were estimated from the calculated complex S-parameters by using Ross-Nicolson method. The validity of our prediction was tested, from comparison of calculated S-parameters with experimental ones measured on a sample made by rapid prototyping, using a modified strip transmission line method. The dielectric enhancement was found to be about 500%, as it was expected from simulations. Applicability of this family of metamaterials to ferrites like applications is discussed.

Zouganelis, Georgios; Rybin, Oleg

2006-11-01

349

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

Science.gov (United States)

Relative rates of the photosensitized production of singlet oxygen ((1)O(2)) and of superoxide (O(2) (•-)) 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 (AlPcS(4)) and pheophorbide-a (PHEO) were used as hydrophilic and hydrophobic photosensitizers, respectively. Xanthine (X) and glutathione (GSH) were used as hydrophobic and hydrophilic SEDs, respectively. The presence of SUVs in the aqueous sample produces the physical separation or encounter of SEDs and photosensitizers according to their membrane binding constants. When both the SED and the photosensitizer are localized within the same phase, a strong decrease in the rate of (1)O(2) formation, united to a strong increase in the rate of O(2) (•-) formation, is observed, relative to when both of these species are localized in different phases. The lipid phase is always present in the biological milieu. Thus, the use of a hydrophobic couple of both dye and SED (as in the case of X and PHEO), as well as a hydrophilic couple of both dye and SED (as in the case of GSH and AlPcS4), should strongly favor the Type I mechanism over the Type II. Since only a small number of hydroxyl radicals are needed to initiate a chain reaction of phospholipid peroxidation, the latter could be more toxic to the tumor tissue than peroxidation by a much higher concentration of singlet oxygen molecules. PMID:22563206

Sanchez-Cruz, Pedro; Dejesus-Andino, Francisco; Alegria, Antonio E

2012-05-15

350

Layer cathode methods of manufacturing and materials for Li-ion rechargeable batteries  

Science.gov (United States)

A positive electrode active material for lithium-ion rechargeable batteries of general formula Li.sub.1+xNi.sub..alpha.Mn.sub..beta.A.sub..gamma.O.sub.2 and further wherein A is Mg, Zn, Al, Co, Ga, B, Zr, or Ti and 0material is manufactured by employing either a solid state reaction method or an aqueous solution method or a sol-gel method which is followed by a rapid quenching from high temperatures into liquid nitrogen or liquid helium.

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

2008-01-01

351

The application of a layer of carbonaceous material to a surface  

International Nuclear Information System (INIS)

A method of applying a carbonaceous material to a surface is described. It consists of exposing the surface to an ionised gas atmosphere generated in a gas consisting substantially of carbon and hydrogen, and applying to the surface through capacitive means an electrical potential which changes in sign at time intervals of between 5 x 10-9 seconds and 10-6 seconds. (author)

352

Quantum electrodynamics near anisotropic polarizable materials: Casimir-Polder shifts near multi-layers of graphene  

CERN Document Server

In a recent paper we have formulated a theory of non-relativistic quantum electrodynamics in the presence of an inhomogeneous Huttner-Barnett dielectric. Here we generalize the formalism to anisotropic materials and show how it may be modified to include conducting surfaces. We start with the derivation of the photon propagator for a slab of material and use it to work out the energy-level shift near a medium whose conductivity in the direction parallel to the surface far exceeds that in the direction perpendicular to the surface. We investigate the influence of the anisotropy of the material's electromagnetic response on the Casimir-Polder shifts, both analytically and numerically, and show that it may have a significant impact on the atom-surface interaction, especially in the non-retarded regime, i.e. for small atom-surface separations. Our results for the energy shift may be used to estimate the Casimir-Polder force acting on quantum objects close to multilayers of graphene or graphite. They are particula...

Eberlein, Claudia

2012-01-01

353

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

354

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

355

A green synthesis of a layered titanate, potassium lithium titanate; lower temperature solid-state reaction and improved materials performance  

Energy Technology Data Exchange (ETDEWEB)

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.

Ogawa, Makoto, E-mail: waseda.ogawa@gmail.com [Graduate School of Creative Science and Engineering, Waseda University, 1-6-1 Nishiwaseda, Shinjuku-ku, Tokyo 169-8050 (Japan); Department of Earth Sciences, Waseda University, 1-6-1 Nishiwaseda, Shinjuku-ku, Tokyo 169-8050 (Japan); Morita, Masashi, E-mail: m-masashi@y.akane.waseda.jp [Graduate School of Creative Science and Engineering, Waseda University, 1-6-1 Nishiwaseda, Shinjuku-ku, Tokyo 169-8050 (Japan); Igarashi, Shota, E-mail: uxei_yoshi_yoshi@yahoo.co.jp [Graduate School of Creative Science and Engineering, Waseda University, 1-6-1 Nishiwaseda, Shinjuku-ku, Tokyo 169-8050 (Japan); Sato, Soh, E-mail: rookie_so_sleepy@yahoo.co.jp [Graduate School of Creative Science and Engineering, Waseda University, 1-6-1 Nishiwaseda, Shinjuku-ku, Tokyo 169-8050 (Japan)

2013-10-15

356

High energy spinel-structured cathode stabilized by layered materials for advanced lithium-ion batteries  

Science.gov (United States)

Due to well-known Jahn-Teller distortion in spinel LiMn1.5Ni0.5O4, it can only be reversibly electrochemically cycled between 3 and 4.8 V with a limited reversible capacity of ?147 mAh g-1. This study intends to embed the layer-structured Li2MnO3 nanodomains into LiMn1.5Ni0.5O4 spinel matrix so that the Jahn-Teller distortion can be suppressed even when the average Mn oxidation state is below +3.5. A series of xLi2MnO3·(1 - x)LiMn1.5Ni0.5O4 where x = 0, 0.1, 0.2, 0.3, 0.4, 0.5 and 1 are synthesized by co-precipitation method. The composites with intermediate values of x = 0.1, 0.2, 0.3, 0.4 and 0.5 exhibit both spinel and layered structural domains in the particles and show greatly improved cycle stability than that of the pure spinel. Among them, 0.3Li2MnO3·0.7LiMn1.5Ni0.5O4 delivers the highest and almost constant capacity after a few conditional cycles and shows superior cycle stability. Ex-situ X-ray diffraction results indicate that no Jahn-Teller distortion occurs during the cycling of the 0.3Li2MnO3·0.7LiMn1.5Ni0.5O4 composite. Additionally, 0.3Li2MnO3·0.7LiMn1.5Ni0.5O4 possesses a high energy density of ?700 Wh kg-1, showing great promise for advanced high energy density lithium-ion batteries.

Lu, Jia; Chang, Ya-Lin; Song, Bohang; Xia, Hui; Yang, Jer-Ren; Lee, Kim Seng; Lu, Li

2014-12-01

357

Synthesis of a novel polyaniline-intercalated layered manganese oxide nanocomposite as electrode material for electrochemical capacitor  

Energy Technology Data Exchange (ETDEWEB)

Polyaniline-intercalated layered manganese oxide (PANI-MnO{sub 2}) nanocomposite was synthesized via exchange reaction of polyaniline (PANI) with n-octadecyltrimethylammonium-intercalated manganese oxide in N-methyl-2-pyrrolidone solvent. The PANI-MnO{sub 2} nanocomposite was characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS), Fourier transform infrared (FTIR) spectroscopy, and so on. XRD analysis showed that the basal spacing was 1.47 nm, corresponding to the benzene rings of PANI were arranged in a zigzag conformation and located perpendicular to the inorganic layers. The C-N stretching vibration ({nu}{sub C-N}) which appeared with PANI at 1293 cm{sup -1} shifted to 1306 cm{sup -1} for PANI-MnO{sub 2} nanocomposite, indicating the existence of interactions between intercalated PANI and manganese oxide layers. The XPS results showed that PANI was still in the conductive form after inserting the polymer into layered manganese oxide. The electrochemical properties as electrode materials for electrochemical capacitors were examined by cyclic voltammetry and galvanostatic charge/discharge test in 0.1 M Na{sub 2}SO{sub 4} solution. The maximum specific capacitance of 330 F g{sup -1} was obtained from galvanostatic charge/discharge at a constant current density of 1 A g{sup -1}. The specific capacitance of PANI-MnO{sub 2} nanocomposite had improvement values of 76 and 59% compared to those of PANI (187 F g{sup -1}) and manganese oxide (208 F g{sup -1}) components, respectively, which was due to synergic effects from each pristine component. (author)

Zhang, Xiong; Ji, Liyan; Yang, Wensheng [State Key Laboratory of Chemical Resource Engineering, Beijing University of Chemical Technology, Beijing 100029 (China); Zhang, Shichao [College of Materials Science and Engineering, Beijing University of Aeronautics and Astronautics, Beijing 100083 (China)

2007-11-15

358

The computer determination of dose-rate distribution of gamma radiation in the layers of various absorbing materials  

International Nuclear Information System (INIS)

An attempt was made to examine the usefulness of the elaborated computer program for calculation of gamma radiation dose rate for technological purposes. The main problem is the determination of radiation dose absorbed in materials of various type, size and kind. To this end the results of computer calculations were compared with those obtained experimentally. For experimental determinations of dose rate the chemical Fricke dosimeter and ionizing chamber were used. Good agreement of the results was obtained for absorbing layers of air, water and aluminium. In case of concrete, on account of the lack of unanimous data concentrating the properties of this material, serious discrepancy was observed. For polymeric low density materials (foamed and granulated polystyrene) of a thickness up to several centimeters the results were close to those calculated for air and water respectively. The present version of the computer program enables one to calculate, with a good accuracy, the radiation dose rate for a given configuration of radiation sources in the irradiated material. Therefore it may be used for technological purposes. (author). 4 refs, 3 figs, 1 tab

359

Facile preparation of hierarchical TiO2 nano structures: growth mechanism and enhanced photocatalytic H2 production from water splitting using methanol as a sacrificial reagent.  

Science.gov (United States)

Owing to unique features, hierarchical nanostructure of TiO2 has superior photocatalytic activity. In this work a facile hydrothermal route has been explored to prepare 3D hierarchical TiO2 (3D-HTiO2), 1D/3D hybrid hierarchical TiO2 composite (HHC), and 3D hierarchical protonated titanate microspheres H2Ti2O5·H2O (3DHPTMS) at the expense of free-standing titania nanotube membrane (TiO2-Memb). It proceeded through the formation of peroxotitanium complex, a water-soluble Ti complex as an intermediate. Mechanism of formation, role of membrane crystallinity, and reaction parameters giving fine control on tuning morphology and crystal structure have been investigated systematically. Photocatalytic activities were determined by measuring the amount hydrogen generated from water splitting under UV irradiation in the presence of methanol as a sacrificial reagent. Self-assembled hierarchical titania nanostructures exhibited much superior photocatalytic activity compared to that of starting material, i.e., TiO2-Memb. Enhanced photocatalytic activity is due to characteristic morphology, increased surface area, and enhanced production of photogenerated charge carriers. PMID:24937083

Haider, Zeeshan; Kang, Young Soo

2014-07-01

360

Hydrogen Storage Materials Based on Single-Layer Aluminum Nitride Nanostructures  

International Nuclear Information System (INIS)

Using the first-principles method based on density functional theory, we study the hydrogen storage properties of Li-doped single-layer aluminum nitride nanostructures (AlN). For the pristine AlN sheet, each Al atom adsorbs one H2 with an average binding energy of 0.14 eV/H2. The hydrogen blinding energies and storage capacities can be markedly increased by doping Li atoms onto the AlN sheet. The charge analysis shows that there are charges transferring from the Li atoms to the AlN sheet, thus the charged Li atoms can polarize hydrogen molecules and enhance the interaction between hydrogen molecules and the AlN sheet. In the fully loaded cases, the Li-doped AlN sheet can contain up to 8.25wt% of molecular hydrogen with an average binding energy of 0.20 eV/H2. (condensed matter: structure, mechanical and thermal properties)

 
 
 
 
361

Positron annihilation lifetime spectroscopy (PALS) application in metal barrier layer integrity for porous low- k materials  

CERN Document Server

Positron Annihilation Lifetime Spectroscopy (PALS) is a useful tool to pre-screen metal barrier integrity for Si-based porous low-k dielectrics. Pore size of low-k, thickness of metal barrier Ta, positronium (Ps) leakage from PALS, trench sidewall morphology, electrical test from one level metal (1LM) pattern wafer and Cu diffusion analysis were all correlated. Macro-porous low-k (pore size >=200 AA) and large scale meso-porous low-k (>50~200 AA) encounter both Ps leakage and Cu diffusion into low-k dielectric in the 0.25 mu mL/0.3 mu mS structures when using SEMATECH in-house PVD Ta 250 AA as barrier layer. For small scale meso-porous (>20~50 AA) and micro- porous (<=20 AA) low-k, no Ps leakage and no Cu diffusion into low-k were observed even with PVD Ta 50 AA, which is proved also owing to sidewall densification to seal all sidewall pores due to plasma etch and ash. For future technology, smaller pore size of porous Si-based low-k (=<50 AA) will be preferential for dense low-k like trench sidewall to...

Simon, Lin; Gidley, D W; Wetzel, J T; Monnig, K A; Ryan, E T; Simon, Jang; Douglas, Yu; Liang, M S; En, W G; Jones, E C; Sturm, J C; Chan, M J; Tiwari, S C; Hirose, M

2002-01-01

362

Highly mesoporous carbonaceous material of activated carbon beads for electric double layer capacitor  

Energy Technology Data Exchange (ETDEWEB)

The activated carbon beads (ACB) are prepared by a new preparation method, which is proposed by mixing the coal tar pitch and fumed silica powder at a certain weight ratio and activation by KOH at different weight ratios and different temperatures. The BET surface area, pore volume and average pore size are obtained based on the nitrogen adsorption isotherms at 77 K by using ASAP 2010 apparatus. The results show that our samples have much high specific surface area (SSA) of 3537 m{sup 2} g{sup -1} and high pore volume value of 305 cm{sup 3} g{sup -1}. The percentage of mesopore volume increases with the weight ratio of KOH/ACB ranging from 4% to 72% The electrochemical double layer capacitors (EDLCs) are assembled with resultant carbon electrode and electrolyte of 1 mol L{sup -1} Et4NBF4/PC. The specific capacitance of the ACB sample could be as high as 191 7 F g{sup -1} by constant current charge/discharge technique, indicating that the ACB presents good characteristics prepared by the method proposed in this work. The investigation of influence of carbon porosity structure on capacitance indicates that the SSA plays an important role on the capacitance and all the pore sizes of less than 1 {mu}. from 1 to 2 nm and larger than 2 {mu} contribute to the capacitance Mesopore structure is beneficial for the performance at high current density.

Feng, Z.H.; Xue, R.S.; Shao, X.H. [Beijing University of Chemical Technology, Beijing (China). College of Science

2010-10-01

363

Impact of Carbon and Tungsten as Divertor Materials on the Scrape-off Layer Conditions in JET  

International Nuclear Information System (INIS)

Full text: In detached divertor conditions, a five-fold stronger reduction of the ion current to the low-field side target plate and a 30% increase in the density limit were observed in neutral-beam heated, low-confinement mode plasmas with the ITER-like Wall compared to the previous carbon wall. These significant differences occurred at higher core densities despite the fact that nearly identical scrape-off layer parameters were measured in attached divertor conditions. When attached, the magnitude and distribution of radiative power as well as the total ion currents to the divertor target plates were measured the same for a range of divertor plasma geometries, including configurations with the high field side strike point on the vertical plate and the low field side strike point on the horizontal plate, and configurations with both strike points on the vertical plates. The 5-to-10-fold reduction of the scrape-off layer carbon content as inferred from low charge state carbon emission, and the fact that both beryllium and tungsten have a low radiation potential in the scrape-off layer, would indicate that the deuterium emission was and still is the dominating radiator. Simulations of deuterium gas fuelling scans with the fluid edge code EDGE2/EIRENE show that replacing carbon with beryllium and tungsten as wall materials leads to reduced impurity radiation, as expected, and translates into an increase in the power conducted to the plates. The ion currents to the plate the plates. The ion currents to the plates, however, are predicted to be similar in both materials configurations. Saturation of the ion currents is predicted at the highest achievable density; the simulations do not predict the reduction of the currents close to the density limit as observed in the experiments. Since the JET ITER-like wall constitutes the same materials and their poloidal distribution as foreseen for the nuclear phase of ITER, understanding the observed differences in the SOL conditions between the two materials configuration, and clarifying the discrepancy between the experimental data and simulations are instrumental for erosion and power handling in ITER. (author)

364

Carbon aerogels as electrode material for electrical double layer supercapacitors-Synthesis and properties  

International Nuclear Information System (INIS)

This paper constitutes a description of technological research the aim of which was to design a symmetric supercapacitor dedicated for the system of quality of electrical energy improvement (supply interruption, voltage dip). The main task was to use the carbon aerogel technology as the efficient method for production of electrode material with desirable properties. Carbon aerogels were prepared by carbonization of resorcinol-formaldehyde (RF) polymer gels. RF-gels were synthesized by curing polycondensation and by the inverse emulsion polymerization of resorcinol with formaldehyde, followed by microwave drying. The morphostructural characteristics of the carbon aerogels were investigated by atomic force microscopy (AFM) and the N2 adsorption (BET method). The electrochemical properties were characterized by means of cycle voltammetry, galvanostatic charging/discharging, and self-discharge.

365

Carbon aerogels as electrode material for electrical double layer supercapacitors-Synthesis and properties  

Energy Technology Data Exchange (ETDEWEB)

This paper constitutes a description of technological research the aim of which was to design a symmetric supercapacitor dedicated for the system of quality of electrical energy improvement (supply interruption, voltage dip). The main task was to use the carbon aerogel technology as the efficient method for production of electrode material with desirable properties. Carbon aerogels were prepared by carbonization of resorcinol-formaldehyde (RF) polymer gels. RF-gels were synthesized by curing polycondensation and by the inverse emulsion polymerization of resorcinol with formaldehyde, followed by microwave drying. The morphostructural characteristics of the carbon aerogels were investigated by atomic force microscopy (AFM) and the N{sub 2} adsorption (BET method). The electrochemical properties were characterized by means of cycle voltammetry, galvanostatic charging/discharging, and self-discharge.

Halama, Agnieszka [Electrotechnical Institute, Division of Electrotechnology and Materials Science, Wroclaw (Poland); Szubzda, Bronislaw, E-mail: szubzda@iel.wroc.p [Electrotechnical Institute, Division of Electrotechnology and Materials Science, Wroclaw (Poland); Pasciak, Grzegorz [Electrotechnical Institute, Division of Electrotechnology and Materials Science, Wroclaw (Poland)

2010-10-30

366

Raman enhancement effect on two-dimensional layered materials: graphene, h-BN and MoS2.  

Science.gov (United States)

Realizing Raman enhancement on a flat surface has become increasingly attractive after the discovery of graphene-enhanced Raman scattering (GERS). Two-dimensional (2D) layered materials, exhibiting a flat surface without dangling bonds, were thought to be strong candidates for both fundamental studies of this Raman enhancement effect and its extension to meet practical applications requirements. Here, we study the Raman enhancement effect on graphene, hexagonal boron nitride (h-BN), and molybdenum disulfide (MoS2), by using the copper phthalocyanine (CuPc) molecule as a probe. This molecule can sit on these layered materials in a face-on configuration. However, it is found that the Raman enhancement effect, which is observable on graphene, hBN, and MoS2, has different enhancement factors for the different vibrational modes of CuPc, depending strongly on the surfaces. Higher-frequency phonon modes of CuPc (such as those at 1342, 1452, 1531 cm(-1)) are enhanced more strongly on graphene than that on h-BN, while the lower frequency phonon modes of CuPc (such as those at 682, 749, 1142, 1185 cm(-1)) are enhanced more strongly on h-BN than that on graphene. MoS2 demonstrated the weakest Raman enhancement effect as a substrate among these three 2D materials. These differences are attributed to the different enhancement mechanisms related to the different electronic properties and chemical bonds exhibited by the three substrates: (1) graphene is zero-gap semiconductor and has a nonpolar C-C bond, which induces charge transfer (2) h-BN is insulating and has a strong B-N bond, while (3) MoS2 is semiconducting with the sulfur atoms on the surface and has a polar covalent bond (Mo-S) with the polarity in the vertical direction to the surface. Therefore, the different Raman enhancement mechanisms differ for each material: (1) charge transfer may occur for graphene; (2) strong dipole-dipole coupling may occur for h-BN, and (3) both charge transfer and dipole-dipole coupling may occur, although weaker in magnitude, for MoS2. Consequently, this work studied the origin of the Raman enhancement (specifically, chemical enhancement) and identifies h-BN and MoS2 as two different types of 2D materials with potential for use as Raman enhancement substrates. PMID:24780008

Ling, Xi; Fang, Wenjing; Lee, Yi-Hsien; Araujo, Paulo T; Zhang, Xu; Rodriguez-Nieva, Joaquin F; Lin, Yuxuan; Zhang, Jin; Kong, Jing; Dresselhaus, Mildred S

2014-06-11

367

A functionalized phosphonate-rich organosilica layered hybrid material (PSLM) fabricated through a mild process for heavy metal uptake.  

Science.gov (United States)

A phosphonate-rich organosilica layered hybrid material (PSLM) made of 3-(trihydroxysilyl)propyl methylphosphonate, monosodium salt, as the single silica source, has been obtained from its aqueous solution through a xerogel process and mild thermal aging. The method is simple, affording bulk quantities of powdered PSLM in a single-step. The hybrid is stable in water and possesses a high content of phosphonate groups fixed on the solid matrix. In addition, PSLM shows good thermal stability, which exceeds 300°C in air. The material was characterized using SEM, TEM, XRD, FT-IR and TGA techniques. Potentiometric titrations show that PSLM bears high-surface density of phosphonate groups (3 mmol g(-1)). As a result, the material displays high metal uptake capacity for heavy metal ions such as Cu(2+) (2.72mmolg(-1)), Pb(2+) (1.67 mmol g(-1)) and Cd(2+) (1.00 mmol g(-1)) at neutral pH values e.g. the pH of natural waters. Detailed theoretical modeling using a Surface Complexation Model combined with Electron Paramagnetic Resonance (EPR) spectroscopy shows that the surface distribution of surface bound Cu(2+) ions is rather homogeneous e.g. copper-binding phosphonate sites are arranged in average distances 5-8?. PMID:24565929

Daikopoulos, Chris; Bourlinos, Athanasios B; Georgiou, Yiannis; Deligiannakis, Yiannis; Zboril, Radek; Karakassides, Michael A

2014-04-15

368

Nano-sized structured layered positive electrode materials to enable high energy density and high rate capability lithium batteries  

Energy Technology Data Exchange (ETDEWEB)

Nano-sized structured dense and spherical layered positive active materials provide high energy density and high rate capability electrodes in lithium-ion batteries. Such materials are spherical second particles made from agglomerated primary particles that are Li.sub.1+.alpha.(Ni.sub.xCo.sub.yMn.sub.z).sub.1-tM.sub.tO.sub.2-dR.sub.d- , where M is selected from can be Al, Mg, Fe, Cu, Zn, Cr, Ag, Ca, Na, K, In, Ga, Ge, V, Mo, Nb, Si, Ti, Zr, or a mixture of any two or more thereof, R is selected from F, Cl, Br, I, H, S, N, or a mixture of any two or more thereof, and 0.ltoreq..alpha..ltoreq.0.50; 0materials and their use in electrochemical devices are also described.

Deng, Haixia; Belharouak, Ilias; Amine, Khalil

2012-10-02

369

Layered double hydroxide/carbon nanotubes composite as a high performance anode material for Ni–Zn secondary batteries  

International Nuclear Information System (INIS)

Nanostructured Zn–Al layered double hydroxide (LDH) and carbon nanotubes (CNTs) have been successfully assembled to form LDH/CNT composite by electrostatic force. The morphology and microstructure of LDH/CNT composites were investigated by transmission electron microscopy and X-ray diffractometer. The assembly mechanism of LDH with CNTs was also discussed. Furthermore, the unique three-dimensional composite thus prepared was used as a new anode material for Ni–Zn secondary batteries to enhance the cell performance for the first time. The electrochemical performances of LDH/CNT composite as anode active material for Ni–Zn cells were investigated by galvanostatic charge/discharge cycling and cyclic voltammogram. The obtained results clearly demonstrated that the LDH/CNT composite had superior cycle stability compared with the conventional ZnO and Zn–Al–LDH, and the discharge capacity could maintain 390 mAh g?1 after 200 cycling tests. At the same time, the LDH/CNT composite also exhibited lower charge plateau voltage and higher discharge plateau voltage, and the average utilization ratio of the anode could reach 95.6%. These results indicated that this kind of composite is a promising anode material for Ni/Zn cells. It exhibits a high capacity (?400 mAh g?1) and high cycling stability

370

In Situ X-ray Absorption Study of a Layered Manganese-chromium Oxide-based Cathode Material  

International Nuclear Information System (INIS)

We have investigated the electronic and atomic structure of a manganese-chromium-based layered oxide material Li(Li0.2Cr0.4Mn0.4)O2 during electrochemical cycling using in situ X-ray absorption spectroscopy. Our results indicate that charge compensation in the cathode material is achieved by the oxidation/reduction of octahedral Cr(III) ions to tetrahedral Cr(VI) ions during delithiation/lithiation. Manganese ions are present predominantly in the Mn(IV) oxidation state and do not appear to actively participate in the charge compensation process. To accommodate the large changes in coordination symmetry of the Cr(III) and Cr(VI) ions, the chromium ions have to move between the regular octahedral sites in the R(bar 3)m-like lattice to interstitial tetrahedral sites during the charge/discharge process. The highly reversible (at least after the first charge) three-electron oxidation/reductions and the easy mobility of the chromium between octahedral and tetrahedral sites are very unusual and interesting. Equally interesting is the fact that chromium is the active metal undergoing oxidation/reduction rather than manganese. Our results also suggest that in the local scale manganese and chromium ions are not evenly distributed in the as-prepared material, but are present in separate domains of Mn and Cr-rich regions.

371

Zirconia layer coated mesoporous silica microspheres as HILIC SPE materials for selective glycopeptide enrichment.  

Science.gov (United States)

Characterization of protein glycosylation requires highly specific methods for the enrichment of glycopeptides because of their sub-stoichiometric glycosylation-site occupancy. The hydrophilic affinity based strategy has attracted more attention, owing to its broad glycan specificity, good reproducibility, and compatibility with mass spectrometric (MS) analysis. Several polar matrices have emerged for hydrophilic interaction chromatography (HILIC) approaches, including sepharose, cellulose, ZIC-HILIC and titania. Here, we present the solid-phase extraction (SPE) utility of zirconia coated mesoporous silica (ZrO(2)/MPS) microspheres for glycopeptide isolation prior to MS analysis. The high specificity of this SPE approach was demonstrated by the enrichment of glycopeptides from the digests of model glycoproteins in HILIC mode. ZrO(2)/MPS microspheres show superior selectivity and glycosylation heterogeneity coverage for glycopeptide enrichment to conventional sepharose. Furthermore, digested mixtures of the phosphoprotein ?-casein and IgG were also treated with ZrO(2)/MPS HILIC SPE materials, which exhibited that glycopeptides could be effectively enriched with interference from phosphorylated peptides. PMID:21897947

Wan, Huihui; Yan, Jingyu; Yu, Long; Sheng, Qianying; Zhang, Xiuli; Xue, Xingya; Li, Xiuling; Liang, Xinmiao

2011-11-01

372

Empirical force fields for complex hydrated calcio-silicate layered materials.  

Science.gov (United States)

The use of empirical force fields is now a standard approach in predicting the properties of hydrated oxides which are omnipresent in both natural and engineering applications. Transferability of force fields to analogous hydrated oxides without rigorous investigations may result in misleading property predictions. Herein, we focus on two common empirical force fields, the simple point charge ClayFF potential and the core-shell potential to study tobermorite minerals, the most prominent family of Calcium-Silicate-Hydrates that are complex hydrated oxides. We benchmark the predictive capabilities of these force fields against first principles results. While the structural information seem to be in close agreement with DFT results, we find that for higher order properties such as elastic constants, the core-shell potential quantitatively improves upon the simple point charge model, and shows a larger degree of transferability to complex materials. In return, to remedy the deficiencies of the simple point charge potential for hydrated calcio-silicates, we suggest using both structural data and elasticity data for potential calibration, a new force field potential, CSH-FF. This re-parameterized version of ClayFF is then applied to simulating an atomistic model of cement (Pellenq et al., PNAS, 2009). We demonstrate that this force field improves the predictive capabilities of ClayFF, being considerably less computational intensive than the core-shell model. PMID:21069228

Shahsavari, Rouzbeh; Pellenq, Roland J-M; Ulm, Franz-Josef

2011-01-21

373

Equation of material balance for systems of double porosity with layer of initial gas  

International Nuclear Information System (INIS)

The physical complexity associated to naturally fractured reservoirs calls for the use of more robust formulations of the Material-Balance Equation (MBE) for determining the initial hydrocarbon in place and predicting reservoir performance. In this paper, we present an improved version of the dual-porosity MBE for naturally fractured reservoirs, published by Penuela et al. (2001), including the existence of an initial gas phase in the reservoir. Considering that a fractured reservoir may be modeled either using different properties for each porous medium or with average values for the total system, two solution techniques based on each of these assumptions are proposed. Convenient arrangements of the equation allow us to estimate not only the original oil and gas volumes but also the relative storage capacity of the porous media (fractures and matrix) and the compressibility for the fractured and total systems. The new equation can be applied to a broader range of reservoirs due to its more general character. The consistency of the expression proposed has been tested with a set of synthetic models exhibiting different storage capacity in the fractures

374

Influence of cathode material and SiCl4 gas on inductively coupled plasma etching of AlGaN layers with Cl2/Ar plasma  

International Nuclear Information System (INIS)

The influence of cathode coverplate material on inductively coupled plasma etching of GaN and AlGaN with 1% and 10% of Al was investigated. It was revealed that coverplate material has a great impact on the etching of Al-containing layers. Results obtained with a graphite coverplate and a Si wafer on top of a quartz coverplate indicate that etch products of coverplate material such as SiClx, CClx reactive species and SiClx+, CClx+ ions play a significant role in fast and smooth etching of Al-containing layers. They act as getters to remove oxygen in the process chamber and as effective etchers for oxide layers formed by background oxygen in the process chamber. Experiments where SiCl4 gas was added to Cl2/Ar plasma confirmed the role of SiClx reactive species and SiClx+ ions for fast and smooth etching of AlGaN layers

375

Atomic layer deposition of materials in the Cu2ZnSnS4 system for nanostructured photovoltaics  

Science.gov (United States)

One of the largest challenges to the widespread adoption of solar energy is the cost. Cu2ZnSnS4 provides an interesting potential solution as a very cheap absorbing material, because the components are earth-abundant (compared to In, Te) and non-toxic (compared to Cd). This work encompasses efforts to produce Cu2ZnSnS4 via atomic layer deposition, with the intent of laying the groundwork for making an extremely thin absorber photovoltaic device. Depositions of the compounds Cu2S, SnS 2, and ZnS are described, with the resulting thin films showing band gaps and stoichiometry similar to bulk samples. The ideal deposition parameters of ZnS were especially of interest due to the use of a newer, non-pyrophoric zinc precursor, Zn(TMHD)2. Multi-layered films of CuxS (x˜2) and ZnS were studied with extended x-ray absorption fine structure measurements, which determined that the films are dominated by copper, while the zinc is relegated to islands on the surface where it oxidizes. This effect is likely due to the incompatible crystal structures of ZnS and Cu2S, and is diminished in films with thicker layers with the ZnS deposited first. Finally, chemical vapor depositions of Cu2S followed by SnS 2 were annealed at 450°C in H2S to produce Cu2SnS 3, which now only requires the addition of CVD ZnS to make Cu2 ZnSnS4 for a photovoltaic device.

Short, Andrew J.

376

Mechanically stacked 1 nm thick carbon nanosheets: Ultrathin layered materials with tunable optical, chemical and electrical properties  

CERN Document Server

Carbon nanosheets are mechanically stable free-standing two-dimensional materials with a thickness of ~1 nm and well defined physical and chemical properties. They are made by radiation induced cross-linking of aromatic self-assembled monolayers. Here we present a route to the scalable fabrication of multilayer nanosheets with tunable electrical, optical and chemical properties on insulating substrates. Stacks up to five nanosheets with sizes of ~1 cm^2 on oxidized silicon were studied. Their optical characteristics were investigated by visual inspection, optical microscopy, UV/Vis reflection spectroscopy and model calculations. Their chemical composition was studied by X-ray photoelectron spectroscopy. The multilayer samples were then annealed in ultra high vacuum at various temperatures up to 1100 K. A subsequent investigation by Raman, X-ray photoelectron and UV/Vis reflection spectroscopy as well as by electrical four-point probe measurements demonstrates that the layered nanosheets transform into nanocry...

Nottbohm, Christoph T; Beyer, Andre; Stosch, Rainer; Golzhauser, Armin; 10.1002/smll.201001993

2011-01-01

377

Combustion-wave propagation in a thin layer of material with gas-phase reaction between fuel and oxidant  

Energy Technology Data Exchange (ETDEWEB)

In the area of study of combustion-wave propagation in a thin layer of material, this work investigates the flame jet and the influence of its size on the velocity and limits of propagation of the combustion wave. The position of the region of intense chemical reaction, the magnitude of the gasification-product flow, and the structure of the flame jet are determined. It is found that combustion-wave propagation in the opposing direction to the oxidant flow is only possible when the edge of the chemical-reaction precedes the point of maximum gasification rate of the fuel. Combustion-wave propagation in a concurrent flow of oxidant is considered analogously.

Rybanin, S.S.; Sobolev, S.L.

1984-01-01

378

Predictions of flow velocity and velocity boundary layer thickness at the surface during laser melting of ceramic materials  

International Nuclear Information System (INIS)

A scaling analysis for momentum and heat transport in the laser-induced melt pool of ceramic materials has been carried out to predict the flow velocity and velocity boundary layer thickness at the melt surface. Compared with analyses available in the literature for momentum and heat transport in the melt pool formed by other high energy density beams, the present scaling analysis has more appropriately incorporated the volumetric heating source in the energy equation and quantified the relative amounts of laser energy consumed by thermal diffusion and by the traverse of the workpiece. The scaling predictions have been assessed by comparison with numerical results of a case study obtained by the present authors, and good qualitative agreement was observed

379

Design of a multifunctional nanohybrid system of the phytohormone gibberellic acid using an inorganic layered double-hydroxide material.  

Science.gov (United States)

To offer a multifunctional and applicable system of the high-value biotechnological phytohormone gibberellic acid (GA), a nanohybrid system of GA using the inorganic Mg-Al layered double-hydroxide material (LDH) was formulated. The ion-exchange technique of LDH was applied to synthesize the GA-LDH hybrid. The hybrid structure of GA-LDH was confirmed by different spectroscopic techniques. The nanohybrid size was described by SEM to be ?0.1 ?m. The GA-LDH nanohybrid structure was the key parameter that controlled GA properties. The layered molecular structure of LDH limited the interaction of GA molecules in two-dimensional directions. Accordingly, GA molecules did not crystallize and were released in an amorphous form suitable for dissolution. At various simulated soil solutions, the nanohybrids showed a sustained release process following Higuchi kinetics. The biodegradation process of the intercalated GA showed an extended period of soil preservation as well as a slow rate of degradation. PMID:20722412

Hafez, Inas H; Berber, Mohamed R; Minagawa, Keiji; Mori, Takeshi; Tanaka, Masami

2010-09-22

380

Improvement of Electrical Contact Between TE Material and Ni Electrode Interfaces by Application of a Buffer Layer  

Science.gov (United States)

A single ?-structure thermoelectric (TE) module based on p-type NaCo2O4, n-type Mg2Si, and Ni electrode was fabricated by the spark plasma sintering (SPS) method. The NaCo2O4 powder was synthesized by using a metal-citric acid complex decomposition method. Bulk Mg2Si prepared by melt quenching was ground into a powder and sieved to particle size of 75 ?m or less. To obtain a sintered body of NaCo2O4 or Mg2Si, the powder was sintered using SPS. Pressed Ni powder or mixed powder consisting of Ni and SrRuO3 powder was inserted between these materials and the Ni electrode in order to connect them, and electrical power was passed through the electrodes from the SPS equipment. The open-circuit voltage ( V OC) values of a single module in which TE materials were connected to the Ni electrodes by using pressed Ni powder was 82.7 mV, and the maximum output current ( I max) and maximum output power ( P max) were 212.4 mA and 6.65 mW at ? T = 470 K, respectively. On the other hand, V OC of a single module in which TE materials and an Ni electrode were connected with a mixed powder (Ni:SrRuO3 = 6:4 volume fraction) was 109 mV, and I max and P max were 4034 mA and 109 mW at ? T = 500 K, respectively. These results indicate that the resistance at the interface between the TE materials and the Ni electrode can be decreased and the output power can be increased by application of a buffer layer consisting of Ni and SrRuO3.

Arai, Koya; Matsubara, Masanori; Sawada, Yukie; Sakamoto, Tatsuya; Kineri, Tohru; Kogo, Yasuo; Iida, Tsutomu; Nishio, Keishi

2012-06-01

 
 
 
 
381

Anion-exchangeable layered materials based on rare-earth phosphors: unique combination of rare-earth host and exchangeable anions.  

Science.gov (United States)

Layered materials, three-dimensional crystals built from stacking two-dimensional components, are attracting intense interest because of their structural anisotropy and the fascinating properties that result. However, the range of such layered materials that can exchange anions is quite small. Continuing efforts have been underway to identify a new class of anion-exchangeable materials. One major goal is the incorporation of rare-earth elements within the host because researchers expect that the marriage of rare-earth skeleton host and the exchangeable species within the interlayer will open up new avenues both for the assembly of layered materials and for the understanding of rare-earth element chemistry. Such lanthanide layered solids have industrial potential. These materials are also of academic importance, serving as an ideal model for studying the cationic size effect on structure stability associated with lanthanide contraction. In this Account, we present the work done by ourselves and others on this novel class of materials. We examine the following four subtopics regarding these layered anionic materials: (1) synthesis strategy and composition diversity, (2) structural features, (3) structure stability with relative humidity, and (4) applications. These materials can be synthesized either by hydrothermal reactions or by homogeneous precipitation, and a variety of anions can be intercalated into the gallery. Although only cations with a suitable size can form the layered structure, the possible range is wide, from early to late lanthanides. We illustrate the effect of lanthanide contraction on properties including morphology, lattice dimensions, and coordination numbers. Because each lanthanide metal ion coordinates water molecules, and the water molecules point directly into the gallery space, this feature plays a critical role in stabilizing the layered structure. In the 9-fold monocapped square antiprism structure, the humidity-triggered transition between high- and low-hydrated phases corresponds to the uptake of H(2)O molecules at the capping site, which provides further evidence of the importance of water coordination. Applications using this unique combination of rare-earth element chemistry and layered materials include ion-exchange, photoluminescence, catalysis, and biomedical devices. Further exploration of the compounds and new methods for functional modification would dramatically enrich the junction of these two fields, leading to a new generation of layered materials with desirable properties. PMID:20560546

Geng, Fengxia; Ma, Renzhi; Sasaki, Takayoshi

2010-09-21

382

Preparation of mesoporous carbon/polypyrrole composite materials and their supercapacitive properties  

Directory of Open Access Journals (Sweden)

Full Text Available We synthesized mesoporous carbons/polypyrrole composites, using a chemical oxidative polymerization and calcium carbonate as a sacrificial template. N2 adsorption-desorption method, Fourier infrared spectroscopy, and transmission electron microscopy were used to characterize the structure and morphology of the composites. The measurement results indicated that as-synthesized carbon with the disordered mesoporous structure and a pore size of approximately 5 nm was uniformly coated by polypyrrole. The electrochemical behavior of the resulting composite was examined by cyclic voltammetry and cycle life measurements, and the obtained results showed that the specific capacitance of the resulting composite electrode was as high as 313 F g?1, nearly twice the capacitance of pure mesoporous carbon electrode (163 F g–1. This reveals that the electrochemical performance of these materials is governed by a combination of the electric double layer capacitance of mesoporous carbon and pseudocapacitance of polypyrrole.

WU-JUN ZOU

2011-08-01

383

Neighboring Hetero-Atom Assistance of Sacrificial Amines to Hydrogen Evolution Using Pt-Loaded TiO2-Photocatalyst  

Directory of Open Access Journals (Sweden)

Full Text Available Photocatalytic H2 evolution was examined using Pt-loaded TiO2-photocatalyst in the presence of amines as sacrificial agents. In the case of amines with all of the carbon attached to the hetero-atom such as 2-aminoethanol, 1,2-diamonoethane, 2-amino-1,3-propanediol, and 3-amino-1,2-propanediol, they were completely decomposed into CO2 and water to quantitatively evolve H2. On the other hand, the amines with both hetero-atoms and one methyl group at the ?-positions (neighboring carbons of amino group such as 2-amino-1-propanol and 1,2-diaminopropane were partially decomposed. Also, the photocatalytic H2 evolution using amines without the hetero-atoms at the ?-positions such as ethylamine, propylamine, 1-butylamine, 1,3-diaminopropane, 2-propylamine, and 2-butylamine was inefficient. Thus, it was found that the neighboring hetero-atom strongly assisted the degradation of sacrificial amines. Moreover, rate constants for H2 evolution were compared among amines. In conclusion, the neighboring hetero-atom did not affect the rate constants but enhanced the yield of hydrogen evolution.

Masahide Yasuda

2014-05-01