Optical waves in a gradient negative-index lens of a half-infinite length.

Science.gov (United States)

Ding, Yi S; Chan, C T; Wang, R P

2013-10-16

Materials with negative permittivity and permeability can overcome the diffraction limit, thereby making the sub-wavelength imaging possible. In this study, we analyze the effects of gradient index on a half-infinite perfect lens. We assume that the sharp interface between the vacuum and the negative-index material is replaced by a smooth transition profile such that the index gradually changing from positive to negative. Interestingly, we find that if the graded index profile is modeled by a tanh function, we can have closed-form analytical solutions for this problem, which is a distinct advantage as numerical solutions are not accurate for evanescent waves with large transverse wave vectors. By analyzing the analytical formulas we confirm that a nonzero total absorption can occur even for a near-zero absorption coefficient in the steady-state limit and the image plane contains multiple sub-wavelength images of an object.

Overlapping illusions by transformation optics without any negative refraction material

Science.gov (United States)

Sun, Fei; He, Sailing

2016-01-01

A novel method to achieve an overlapping illusion without any negative refraction index material is introduced with the help of the optic-null medium (ONM) designed by an extremely stretching spatial transformation. Unlike the previous methods to achieve such an optical illusion by transformation optics (TO), our method can achieve a power combination and reshape the radiation pattern at the same time. Unlike the overlapping illusion with some negative refraction index material, our method is not sensitive to the loss of the materials. Other advantages over existing methods are discussed. Numerical simulations are given to verify the performance of the proposed devices.

Origami with negative refractive index to generate super-lenses

International Nuclear Information System (INIS)

Guenneau, Fanny; Chakrabarti, Sangeeta; Guenneau, Sebastien; Ramakrishna, S Anantha

2014-01-01

Negative refractive index materials (NRIM) enable unique effects including superlenses with a high degree of sub-wavelength image resolution, a capability that stems from the ability of NRIM to support a host of surface plasmon states. Using a generalized lens theorem and the powerful tools of transformational optics, a variety of focusing configurations involving complementary positive and negative refractive index media can be generated. A paradigm of such complementary media are checkerboards that consist of alternating cells of positive and negative refractive index, and are associated with very singular electromagnetics. We present here a variety of multi-scale checkerboard lenses that we call origami lenses and investigate their electromagnetic properties both theoretically and computationally. Some of these meta-structures in the plane display thin bridges of complementary media, and this highly enhances their plasmonic response. We demonstrate the design of three-dimensional checkerboard meta-structures of complementary media using transformational optics to map the checkerboard onto three-dimensional corner lenses, the only restriction being that the corresponding unfolded structures in the plane are constrained by the four color-map theorem. (paper)

A single-layer wide-angle negative-index metamaterial at visible frequencies.

Science.gov (United States)

Burgos, Stanley P; de Waele, Rene; Polman, Albert; Atwater, Harry A

2010-05-01

Metamaterials are materials with artificial electromagnetic properties defined by their sub-wavelength structure rather than their chemical composition. Negative-index materials (NIMs) are a special class of metamaterials characterized by an effective negative index that gives rise to such unusual wave behaviour as backwards phase propagation and negative refraction. These extraordinary properties lead to many interesting functions such as sub-diffraction imaging and invisibility cloaking. So far, NIMs have been realized through layering of resonant structures, such as split-ring resonators, and have been demonstrated at microwave to infrared frequencies over a narrow range of angles-of-incidence and polarization. However, resonant-element NIM designs suffer from the limitations of not being scalable to operate at visible frequencies because of intrinsic fabrication limitations, require multiple functional layers to achieve strong scattering and have refractive indices that are highly dependent on angle of incidence and polarization. Here we report a metamaterial composed of a single layer of coupled plasmonic coaxial waveguides that exhibits an effective refractive index of -2 in the blue spectral region with a figure-of-merit larger than 8. The resulting NIM refractive index is insensitive to both polarization and angle-of-incidence over a +/-50 degree angular range, yielding a wide-angle NIM at visible frequencies.

Bulk material engineering and procurement management of NPS

International Nuclear Information System (INIS)

Fu Sanhong; Fan Kai

2005-01-01

In a nuclear power project, bulk material is often not in an outstanding position, compared to equipment, yet bulk material is one of most difficult part in engineering and procurement management. If the schedule is not in good control, it will seriously hamper the progress of the whole project. The article explores bulk material engineering and procurement management of NPS, illustrated with tables and graphs. First, major difficult aspects of bulk material procurement are described. On one hand, bulk material is really bulky in kind. We must have detail information of manufacturers, manufacture duration, and take good control of bidding schedule. On the other hand, when an order is placed, we need to make clear everything in the procurement package, such as material types, delivery batches, quantity of each batch and delivery schedule, which is a tremendous work. Then, a schedule conflict is analyzed: when an order is placed, the detail type and quantity cannot be defined (since the construction design is not finished yet). To settle this conflict, the concept 'Requirement Schedule Curve' is brought forward, along with the calculation method. To get this curve, we need to make use of the technical data of the reference power station, along with the site construction schedule, to produce a site quantity requirement curve varying from time, for each type of material. Last, based on the 'Requirement Schedule Curve', we are able to build a unified database to control the engineering, procurement, manufacturing and delivery schedule, so as to procure precisely, manufacture on time, and optimize the storage. In this way, the accurate control of bulk material engineering and procurement schedule can be achieved. (authors)

On metallic gratings coated conformally with isotropic negative-phase-velocity materials

International Nuclear Information System (INIS)

Inchaussandague, Marina E.; Lakhtakia, Akhlesh; Depine, Ricardo A.

2008-01-01

Application of the differential method (also called the C method) to plane-wave diffraction by a perfectly conducting, sinusoidally corrugated metallic grating coated with a linear, homogeneous, isotropic, lossless dielectric-magnetic material shows that coating materials with negative index of refraction may deliver enhanced maximum nonspecular reflection efficiencies in comparison to coating materials with positive index of refraction

On metallic gratings coated conformally with isotropic negative-phase-velocity materials

Energy Technology Data Exchange (ETDEWEB)

Inchaussandague, Marina E. [GEA-Grupo de Electromagnetismo Aplicado, Departamento de Fisica, Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires, Ciudad Universitaria, Pabellon I, 1428 Buenos Aires (Argentina); CONICET-Consejo Nacional de Investigaciones Cientificas y Tecnicas, Rivadavia 1917, Buenos Aires (Argentina)], E-mail: mei@df.uba.ar; Lakhtakia, Akhlesh [CATMAS-Computational and Theoretical Materials Sciences Group, Department of Engineering Science and Mechanics, Pennsylvania State University, University Park, PA 16802-6812 (United States)], E-mail: akhlesh@psu.edu; Depine, Ricardo A. [GEA-Grupo de Electromagnetismo Aplicado, Departamento de Fisica, Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires, Ciudad Universitaria, Pabellon I, 1428 Buenos Aires (Argentina); CONICET-Consejo Nacional de Investigaciones Cientificas y Tecnicas, Rivadavia 1917, Buenos Aires (Argentina)], E-mail: rdep@df.uba.ar

2008-03-31

Application of the differential method (also called the C method) to plane-wave diffraction by a perfectly conducting, sinusoidally corrugated metallic grating coated with a linear, homogeneous, isotropic, lossless dielectric-magnetic material shows that coating materials with negative index of refraction may deliver enhanced maximum nonspecular reflection efficiencies in comparison to coating materials with positive index of refraction.

Gigantic negative magnetoresistance in the bulk of a disordered topological insulator

Science.gov (United States)

Breunig, Oliver; Wang, Zhiwei; Taskin, A. A.; Lux, Jonathan; Rosch, Achim; Ando, Yoichi

2017-05-01

With the recent discovery of Weyl semimetals, the phenomenon of negative magnetoresistance (MR) is attracting renewed interest. Large negative MR is usually related to magnetism, but the chiral anomaly in Weyl semimetals is a rare exception. Here we report a mechanism for large negative MR which is also unrelated to magnetism but is related to disorder. In the nearly bulk-insulating topological insulator TlBi0.15Sb0.85Te2, we observed gigantic negative MR reaching 98% in 14 T at 10 K, which is unprecedented in a nonmagnetic system. Supported by numerical simulations, we argue that this phenomenon is likely due to the Zeeman effect on a barely percolating current path formed in the disordered bulk. Since disorder can also lead to non-saturating linear MR in Ag2+δSe, the present finding suggests that disorder engineering in narrow-gap systems is useful for realizing gigantic MR in both positive and negative directions.

Gigantic negative magnetoresistance in the bulk of a disordered topological insulator

Science.gov (United States)

Breunig, Oliver; Wang, Zhiwei; Taskin, A A; Lux, Jonathan; Rosch, Achim; Ando, Yoichi

2017-01-01

With the recent discovery of Weyl semimetals, the phenomenon of negative magnetoresistance (MR) is attracting renewed interest. Large negative MR is usually related to magnetism, but the chiral anomaly in Weyl semimetals is a rare exception. Here we report a mechanism for large negative MR which is also unrelated to magnetism but is related to disorder. In the nearly bulk-insulating topological insulator TlBi0.15Sb0.85Te2, we observed gigantic negative MR reaching 98% in 14 T at 10 K, which is unprecedented in a nonmagnetic system. Supported by numerical simulations, we argue that this phenomenon is likely due to the Zeeman effect on a barely percolating current path formed in the disordered bulk. Since disorder can also lead to non-saturating linear MR in Ag2+δSe, the present finding suggests that disorder engineering in narrow-gap systems is useful for realizing gigantic MR in both positive and negative directions. PMID:28541291

On binding energy of trions in bulk materials

Science.gov (United States)

Filikhin, Igor; Kezerashvili, Roman Ya.; Vlahovic, Branislav

2018-03-01

We study the negatively T- and positively T+ charged trions in bulk materials in the effective mass approximation within the framework of a potential model. The binding energies of trions in various semiconductors are calculated by employing Faddeev equation in configuration space. Results of calculations of the binding energies for T- are consistent with previous computational studies and are in reasonable agreement with experimental measurements, while the T+ is unbound for all considered cases. The mechanism of formation of the binding energy of trions is analyzed by comparing contributions of a mass-polarization term related to kinetic energy operators and a term related to the Coulomb repulsion of identical particles.

Optical bistability induced by quantum coherence in a negative index atomic medium

International Nuclear Information System (INIS)

Zhang Hong-Jun; Sun Hui; Li Jin-Ping; Yin Bao-Yin; Guo Hong-Ju

2013-01-01

Bistability behaviors in an optical ring cavity filled with a dense V-type four-level atomic medium are theoretically investigated. It is found that the optical bistability can appear in the negative refraction frequency band, while both the bistability and multi-stability can occur in the positive refraction frequency bands. Therefore, optical bistability can be realized from conventional material to negative index material due to quantum coherence in our scheme. (electromagnetism, optics, acoustics, heat transfer, classical mechanics, and fluid dynamics)

The electromagnetically induced negative refractive index in the Er3+:YAlO3 crystal

International Nuclear Information System (INIS)

Liu Chunxu; Zhang Jisen; Liu Junye; Jin Guang

2009-01-01

We carried out the negative refractive index in the solid medium Er 3+ :YAlO 3 crystal with a Λ-type four-level scheme proposed for atomic vapour by Thommen and Mandel, and Kaestel (Phys. Rev. Lett. 2006 96 053601 and 2007 98 069301) based on quantum interference and electromagnetically induced transparency (EIT). The results show that the frequency band with the negative index is much wider (∼1 MHz) than reported previously. Usually, Im[n] is always positive, corresponding to absorption, and the figure of merit (FOM, the ratio of real to imaginary, namely |Re[n]/Im[n]|) is only on the order of unity. We achieve FOM |Re[n]/Im[n]| = 4.6. The corresponding negative Im[n] is related to the stimulated emission of 4 I 13/2 → 4 I 15/2 of the rare earth ion Er 3+ under external electromagnetic fields. It is concluded that the rare earth ion doped material with abundant energy levels and various electric and magnetic transitions is an outstanding and practical candidate for the electromagnetically induced negative refractive index material.

Design of negative refractive index metamaterial with water droplets using 3D-printing

Science.gov (United States)

Shen, Zhaoyang; Yang, Helin; Huang, Xiaojun; Yu, Zetai

2017-11-01

We numerically and experimentally demonstrate a negative refractive index (NRI) behavior in combined water droplets and photosensitive resin materials operating in the microwave regime. The NRI is achieved over a very wide frequency range in 10.27-15 GHz with bandwidth of 4.63 GHz. The simulated results approximately agree with the experimental results. The negative index band can be controlled by water droplet radius. The proposed metamaterial production process is simple and may have potential applications in broadband tunable devices.

Structures with negative index of refraction

Science.gov (United States)

Soukoulis, Costas M [Ames, IA; Zhou, Jiangfeng [Ames, IA; Koschny, Thomas [Ames, IA; Zhang, Lei [Ames, IA; Tuttle, Gary [Ames, IA

2011-11-08

The invention provides simplified negative index materials (NIMs) using wire-pair structures, 4-gap single ring split-ring resonator (SRR), fishnet structures and overleaf capacitor SRR. In the wire-pair arrangement, a pair of short parallel wires and continuous wires are used. In the 4-gap single-ring SRR, the SRRs are centered on the faces of a cubic unit cell combined with a continuous wire type resonator. Combining both elements creates a frequency band where the metamaterial is transparent with simultaneously negative .di-elect cons. and .mu.. In the fishnet structure, a metallic mesh on both sides of the dielectric spacer is used. The overleaf capacitor SRR changes the gap capacities to small plate capacitors by making the sections of the SRR ring overlap at the gaps separated by a thin dielectric film. This technique is applicable to conventional SRR gaps but it best deploys for the 4-gap single-ring structures.

Combining item and bulk material loss-detection uncertainties

International Nuclear Information System (INIS)

Eggers, R.F.

1982-01-01

Loss detection requirements, such as five formula kilograms with 99% probability of detection, which apply to the sum of losses from material in both item and bulk form, constitute a special problem for the nuclear material statistician. Requirements of this type are included in the Material Control and Accounting Reform Amendments described in the Advance Notice of Proposed Rule Making (Federal Register, 46(175):45144-46151). Attribute test sampling of items is the method used to detect gross defects in the inventory of items in a given control unit. Attribute sampling plans are designed to detect a loss of a specificed goal quantity of material with a given probability. In contrast to the methods and statistical models used for item loss detection, bulk material loss detection requires all the material entering and leaving a control unit to be measured and the calculation of a loss estimator that will be tested against an appropriate alarm threshold. The alarm threshold is determined from an estimate of the error inherent in the components of the loss estimator. In this paper a simple grahical method of evaluating the combined capabilities of bulk material loss detection methods and item attribute testing procedures will be described. Quantitative results will be given for several cases, indicating how a decrease in the precision of the item loss detection method tends to force an increase in the precision of the bulk loss detection procedure in order to meet the overall detection requirement. 4 figures

Formulating Fermat's principle for light traveling in negative refraction materials

International Nuclear Information System (INIS)

Veselago, Viktor G

2002-01-01

The formulation of Fermat's principle for electromagnetic waves traveling in materials with a negative refractive index is refined. It is shown that a formulation in terms of the minimum (or extremum) of wave travel time between two points is not correct in general. The correct formulation involves the extremum of the total optical length, with the optical length for the wave propagation through left-handed materials taken to be negative. (methodological notes)

Femtosecond laser damage threshold and nonlinear characterization in bulk transparent SiC materials

International Nuclear Information System (INIS)

DesAutels, G. Logan; Finet, Marc; Ristich, Scott; Whitaker, Matt; Brewer, Chris; Juhl, Shane; Walker, Mark; Powers, Peter

2008-01-01

Semi-insulating and conducting SiC crystalline transparent substrates were studied after being processed by femtosecond (fs) laser radiation (780 nm at 160 fs). Z-scan and damage threshold experiments were performed on both SiC bulk materials to determine each sample's nonlinear and threshold parameters. 'Damage' in this text refers to an index of refraction modification as observed visually under an optical microscope. In addition, a study was performed to understand the damage threshold as a function of numerical aperture. Presented here for the first time, to the best of our knowledge, are the damage threshold, nonlinear index of refraction, and nonlinear absorption measured values

Bulk material management mode of general contractors in nuclear power project

International Nuclear Information System (INIS)

Zhang Jinyong; Zhao Xiaobo

2011-01-01

The paper introduces the characteristics of bulk material management mode in construction project, and the advantages and disadvantages of bulk material management mode of general contractors in nuclear power project. In combination with the bulk material management mode of China Nuclear Power Engineering Co., Ltd, some improvement measures have been put forward as well. (authors)

Forecasting Dry Bulk Freight Index with Improved SVM

Directory of Open Access Journals (Sweden)

Qianqian Han

2014-01-01

Full Text Available An improved SVM model is presented to forecast dry bulk freight index (BDI in this paper, which is a powerful tool for operators and investors to manage the market trend and avoid price risking shipping industry. The BDI is influenced by many factors, especially the random incidents in dry bulk market, inducing the difficulty in forecasting of BDI. Therefore, to eliminate the impact of random incidents in dry bulk market, wavelet transform is adopted to denoise the BDI data series. Hence, the combined model of wavelet transform and support vector machine is developed to forecast BDI in this paper. Lastly, the BDI data in 2005 to 2012 are presented to test the proposed model. The 84 prior consecutive monthly BDI data are the inputs of the model, and the last 12 monthly BDI data are the outputs of model. The parameters of the model are optimized by genetic algorithm and the final model is conformed through SVM training. This paper compares the forecasting result of proposed method and three other forecasting methods. The result shows that the proposed method has higher accuracy and could be used to forecast the short-term trend of the BDI.

Relation between Raman backscattering from droplets and bulk water: Effect of refractive index dispersion

Science.gov (United States)

Plakhotnik, Taras; Reichardt, Jens

2018-03-01

A theoretical framework is presented that permits investigations of the relation between inelastic backscattering from microparticles and bulk samples of Raman-active materials. It is based on the Lorentz reciprocity theorem and no fundamental restrictions concerning the microparticle shape apply. The approach provides a simple and intuitive explanation for the enhancement of the differential backscattering cross-section in particles in comparison to bulk. The enhancement factor for scattering of water droplets in the diameter range from 0 to 60 μm (vitally important for the a priori measurement of liquid water content of warm clouds with spectroscopic Raman lidars) is about a factor of 1.2-1.6 larger (depending on the size of the sphere) than an earlier study has shown. The numerical calculations are extended to 1000 μm and demonstrate that dispersion of the refractive index of water becomes an important factor for spheres larger than 100 μm. The physics of the oscillatory phenomena predicted by the simulations is explained.

High-negative effective refractive index of silver nanoparticles system in nanocomposite films

Science.gov (United States)

Altunin, Konstantin K.; Gadomsky, Oleg N.

2012-03-01

We have proved on the basis of the experimental optical reflection and transmission spectra of the nanocomposite film of poly(methyl methacrylate) with silver nanoparticles that (PMMA + Ag) nanocomposite films have quasi-zero refractive indices in the optical wavelength range. We show that to achieve quasi-zero values of the complex index of refraction of composite materials is necessary to achieve high-negative effective refractive index in the system of spherical silver nanoparticles.

High temperature superconductor bulk materials. Fundamentals - processing - properties control - application aspects

International Nuclear Information System (INIS)

Krabbes, G.; Fuchs, G.; Canders, W.R.; May, H.; Palka, R.

2006-01-01

This book presents all the features of bulk high temperature superconducting materials. Starting from physical and chemical fundamentals, the authors move on to portray methods and problems of materials processing, thoroughly working out the characteristic properties of bulk superconductors in contrast to long conductors and films. The authors provide a wide range of specific materials characteristics with respect to the latest developments and future applications guiding from fundamentals to practical engineering examples. This book contains the following chapters: 1. Fundamentals 2. Growth and melt processing of YBCO 3. Pinning-relevant defects in bulk YBCO 4. Properties of bulk YBCO 5. Trapped fields 6. Improved YBCO based bulk superconductors and functional elements 7. Alternative systems 8. Peak effect 9. Very high trapped fields in YBCO permanent magnets 10. Engineering aspects: Field distribution in bulk HTSC 11. Inherently stable superconducting magnetic bearings 12. Application of bulk HTSCs in electromagnetic energy converters 13. Applications in magnet technologies and power supplies

Electromagnetic forces in negative-refractive-index metamaterials: A first-principles study

Science.gov (United States)

Yannopapas, Vassilios; Galiatsatos, Pavlos G.

2008-04-01

According to the theory of Veselago, when a particle immersed within a metamaterial with negative refractive index is illuminated by plane wave, it experiences a reversed radiation force due to the antiparallel directions of the phase velocity and energy flow. By employing an ab initio method, we show that, in the limit of zero losses, the effect of reversed radiation pressure is generally true only for the specular beam. Waves generated by diffraction of the incident light at the surface of the slab of the metamaterial can produce a total force which is parallel to the radiation flow. However, when the actual losses of the materials are taken into account, the phenomenon of reversed radiation force is evident within the whole range of a negative refractive index band.

Epitaxially Grown Layered MFI–Bulk MFI Hybrid Zeolitic Materials

KAUST Repository

Kim, Wun-gwi

2012-11-27

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 μm), 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 N2 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 CO2 and good CO2/CH4 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 CO2 and CH4 gas permeabilities of the interpenetrated layer at the BMLM/polyimide interface. © 2012 American Chemical Society.

Carbon nanotubes grown on bulk materials and methods for fabrication

Science.gov (United States)

Menchhofer, Paul A [Clinton, TN; Montgomery, Frederick C [Oak Ridge, TN; Baker, Frederick S [Oak Ridge, TN

2011-11-08

Disclosed are structures formed as bulk support media having carbon nanotubes formed therewith. The bulk support media may comprise fibers or particles and the fibers or particles may be formed from such materials as quartz, carbon, or activated carbon. Metal catalyst species are formed adjacent the surfaces of the bulk support material, and carbon nanotubes are grown adjacent the surfaces of the metal catalyst species. Methods employ metal salt solutions that may comprise iron salts such as iron chloride, aluminum salts such as aluminum chloride, or nickel salts such as nickel chloride. Carbon nanotubes may be separated from the carbon-based bulk support media and the metal catalyst species by using concentrated acids to oxidize the carbon-based bulk support media and the metal catalyst species.

Self-closing sheet for encapsulating and dumping a bulk of material

DEFF Research Database (Denmark)

2017-01-01

The invention relates to a sheet (1) to be placed in relation to a split barge (100) for encapsulating a bulk of material (101) to be dumped when the bulk of material is released, the sheet comprising a material containing portion (4) and at least one material free portion (3) extending from...

Materials processing and machine applications of bulk HTS

Science.gov (United States)

Miki, M.; Felder, B.; Tsuzuki, K.; Xu, Y.; Deng, Z.; Izumi, M.; Hayakawa, H.; Morita, M.; Teshima, H.

2010-12-01

We report a refrigeration system for rotating machines associated with the enhancement of the trapped magnetic flux of bulk high-temperature superconductor (HTS) field poles. A novel cryogenic system was designed and fabricated. It is composed of a low-loss rotary joint connecting the rotor and a closed-cycle thermosiphon under a GM cryocooler using a refrigerant. Condensed neon gas was adopted as a suitable cryogen for the operation of HTS rotating machines with field poles composed of RE-Ba-Cu-O family materials, where RE is a rare-earth metal. Regarding the materials processing of the bulks HTS, thanks to the addition of magnetic particles to GdBa2Cu3O7 - d (Gd123) bulk superconductors an increase of more than 20% in the trapped magnetic flux density was achieved at liquid nitrogen temperature. Field-pole Gd123 bulks up to 46 mm in diameter were synthesized with the addition of Fe-B alloy magnetic particles and assembled into the synchronous machine rotor to be tested. Successful cooling of the magnetized rotor field poles down to 35 K and low-output-power rotating operation was achieved up to 720 rpm in the test machine with eight field-pole bulks. The present results show a substantial basis for making a prototype system of rotating machinery of applied HTS bulks.

Materials processing and machine applications of bulk HTS

Energy Technology Data Exchange (ETDEWEB)

Miki, M; Felder, B; Tsuzuki, K; Xu, Y; Deng, Z; Izumi, M [Department of Marine Electronics and Mechanical Engineering, Tokyo University of Marine Science and Technology, 2-1-6, Etchu-jima, Koto-ku, Tokyo 135-8533 (Japan); Hayakawa, H [Kitano Seiki Co. Ltd, 7-17-3, Chuo, Ohta-ku, Tokyo 143-0024 (Japan); Morita, M; Teshima, H, E-mail: d082025@kaiyodai.ac.j [Nippon Steel Co. Ltd, 20-1, Shintomi, Huttsu-shi, Chiba 293-8511 (Japan)

2010-12-15

We report a refrigeration system for rotating machines associated with the enhancement of the trapped magnetic flux of bulk high-temperature superconductor (HTS) field poles. A novel cryogenic system was designed and fabricated. It is composed of a low-loss rotary joint connecting the rotor and a closed-cycle thermosiphon under a GM cryocooler using a refrigerant. Condensed neon gas was adopted as a suitable cryogen for the operation of HTS rotating machines with field poles composed of RE-Ba-Cu-O family materials, where RE is a rare-earth metal. Regarding the materials processing of the bulks HTS, thanks to the addition of magnetic particles to GdBa{sub 2}Cu{sub 3}O{sub 7-d} (Gd123) bulk superconductors an increase of more than 20% in the trapped magnetic flux density was achieved at liquid nitrogen temperature. Field-pole Gd123 bulks up to 46 mm in diameter were synthesized with the addition of Fe-B alloy magnetic particles and assembled into the synchronous machine rotor to be tested. Successful cooling of the magnetized rotor field poles down to 35 K and low-output-power rotating operation was achieved up to 720 rpm in the test machine with eight field-pole bulks. The present results show a substantial basis for making a prototype system of rotating machinery of applied HTS bulks.

The optimisation of transfer chutes in the bulk materials industry / M.N. van Aarde

OpenAIRE

Van Aarde, Michiel Nicolaas

2009-01-01

Bulk materials handling is a rapidly growing global industry. Immense challenges exist to improve the efficiency and cost effectiveness of transporting and handling bulk materials continuously. The nature and scale of bulk materials handling varies from country to country. This study specifically focuses on the handling of bulk materials in the mining sector. Within this industry, transfer chutes are a key component used for transferring bulk material from one conveyor to another. Among o...

Ultra-low thermal expansion realized in giant negative thermal expansion materials through self-compensation

OpenAIRE

Fei-Ran Shen; Hao Kuang; Feng-Xia Hu; Hui Wu; Qing-Zhen Huang; Fei-Xiang Liang; Kai-Ming Qiao; Jia Li; Jing Wang; Yao Liu; Lei Zhang; Min He; Ying Zhang; Wen-Liang Zuo; Ji-Rong Sun

2017-01-01

Materials with zero thermal expansion (ZTE) or precisely tailored thermal expansion are in urgent demand of modern industries. However, the overwhelming majority of materials show positive thermal expansion. To develop ZTE or negative thermal expansion (NTE) materials as compensators has become an important challenge. Here, we present the evidence for the realization of ultra-low thermal expansion in Mn–Co–Ge–In particles. The bulk with the Ni2In-type hexagonal structure undergoes giant NTE o...

Chiral metamaterials: from optical activity and negative refractive index to asymmetric transmission

International Nuclear Information System (INIS)

Li, Zhaofeng; Mutlu, Mehmet; Ozbay, Ekmel

2013-01-01

We summarize the progress in the development and application of chiral metamaterials. After a brief review of the salient features of chiral metamaterials, such as giant optical activity, circular dichroism, and negative refractive index, the common method for the retrieval of effective parameters for chiral metamaterials is surveyed. Then, we introduce some typical chiral structures, e.g., chiral metamaterial consisting of split ring resonators, complementary chiral metamaterial, and composite chiral metamaterial, on the basis of the studies of the authors’ group. The coupling effect during the construction of bulk chiral metamaterials is mentioned and discussed. We introduce the application of bianisotropic chiral structures in the field of asymmetric transmission. Finally, we mention a few directions for future research on chiral metamaterials. (review article)

Femtosecond index change mechanisms and morphology of SiC crystalline materials

International Nuclear Information System (INIS)

DesAutels, Logan; Brewer, Christopher; Powers, Peter; Walker, Mark; Tomlin, David; Fratini, Albert; Juhl, Shane; Chen Weibin

2009-01-01

Femtosecond lasers have a unique ability of processing bulk transparent materials for various applications such as micromachining, waveguide manufacturing, and photonic bandgap structures just to name a few. These applications depend on the formation of micron or submicron size features that are known to be index modifications to the bulk substrate [H. Guo, H. Jiang, Y. Fang, C. Peng, H. Yang, Y. Li, Q. Gong, J. Opt. A: Pure Appl. Opt. 6 (2004) 787]. To the best of our knowledge the physical understanding of how these index-modified features are formed is still unknown, but many good theories exist such as Petite et al. [G. Petite, P. Daguzan, S. Guizard, P. Martin, in: IEEE Annual Report Conference on Electrical Insulation and Dielectric Phenomena, vol. 15, IEEE, 1995, pp. 40-44] or Tien et al. [A. Tien, S. Backus, H. Kapteyn, M. Murnane, G. Mourou, Phys. Rev. Lett. 82 (1999) 3883]. In this Letter the question on the physical cause for index changes is investigated by the combined efforts between Wright-Patterson AFB (WPAFB) and the University of Dayton (UD) using numerous imaging equipment such as TEM, AFM, NSOM, Nomarski microscopy, X-ray crystallography, Raman spectroscopy, and even diffraction efficiency experiments. With all the combined imaging equipment this research is able to present valuable data and deduce plausible theories of the physics of the index modification mechanism

Double Negative Materials (DNM), Phenomena and Applications

Science.gov (United States)

2009-07-01

5697–5711. Maksimović, M., and Z. Jakšić. “Emittance and Absorptance Tailoring by Negative Refractive Index Metamaterial-Based Cantor Multilayers.” J...TOKEN=48950826 Popov, A. K., S. A. Myslivets, T. F. George , and V. M. Shalaev. “Tailoring Transparency of Negative-Index Metamaterials With Parametric...Popov, A. K., S. A. Myslivets, T. F. George , and V. M. Shalaev. “Compensating Losses in Positive- and Negative-Index Metamaterials Through

Characterization of Zeolite in Zeolite-Geopolymer Hybrid Bulk Materials Derived from Kaolinitic Clays

Directory of Open Access Journals (Sweden)

Hayami Takeda

2013-05-01

Full Text Available Zeolite-geopolymer hybrid materials have been formed when kaolin was used as a starting material. Their characteristics are of interest because they can have a wide pore size distribution with micro- and meso-pores due to the zeolite and geopolymer, respectively. In this study, Zeolite-geopolymer hybrid bulk materials were fabricated using four kinds of kaolinitic clays (a halloysite and three kinds of kaolinite. The kaolinitic clays were first calcined at 700 °C for 3 h to transform into the amorphous aluminosilicate phases. Alkali-activation treatment of the metakaolin yielded bulk materials with different amounts and types of zeolite and different compressive strength. This study investigated the effects of the initial kaolinitic clays on the amount and types of zeolite in the resultant geopolymers as well as the strength of the bulk materials. The kaolinitic clays and their metakaolin were characterized by XRD analysis, chemical composition, crystallite size, 29Si and 27Al MAS NMR analysis, and specific surface area measurements. The correlation between the amount of zeolite formed and the compressive strength of the resultant hybrid bulk materials, previously reported by other researchers was not positively observed. In the studied systems, the effects of Si/Al and crystalline size were observed. When the atomic ratio of Si/Al in the starting kaolinitic clays increased, the compressive strength of the hybrid bulk materials increased. The crystallite size of the zeolite in the hybrid bulk materials increased with decreasing compressive strength of the hybrid bulk materials.

The homogenisation of bulk material in blending piles.

NARCIS (Netherlands)

Gerstel, A.W.

1979-01-01

In this thesis the homogenisation of bulk material in three types of piles is dealt with. The homogenisation implies that the fluctuations of a material proprety in the input flow of the pile are transformed into output fluctuations, whereby the latter ones are evened out. Analyses are presented

Device for determining the content of bulk materials on conveyor belts

International Nuclear Information System (INIS)

Fritsche, D.

1983-01-01

On the basis of the forward scattering of photon radiation the invention is aimed at determining the content of bulk material, in particular the ash content of lignite, independently of the height of the material conveyed by belts. This could be achieved by making the radiation source support movable, so that the distance between source and conveyor belt is variable and adaptable to the mean height of the bulk material

Cast bulk metallic glass alloys: prospects as wear materials

Energy Technology Data Exchange (ETDEWEB)

Hawk, Jeffrey A.; Dogan, Omer N.; Shiflet, Gary J. (Dept. of Materials Science and Engineering, University of Virginia, Charlottesville, VA)

2005-01-01

Bulk metallic glasses are single phase materials with unusual physical and mechanical properties. One intriguing area of possible use is as a wear material. Usually, pure metals and single phase dilute alloys do not perform well in tribological conditions. When the metal or alloy is lightweight, it is usually soft leading to galling in sliding situations. For the harder metals and alloys, their density is usually high, so there is an energy penalty when using these materials in wear situations. However, bulk metallic glasses at the same density are usually harder than corresponding metals and dilute single phase alloys, and so could offer better wear resistance. This work will discuss preliminary wear results for metallic glasses with densities in the range of 4.5 to 7.9 g/cc. The wear behavior of these materials will be compared to similar metals and alloys.

Apparatus for measuring moisture in moving bulk material using a lithium-7 radiation source

International Nuclear Information System (INIS)

Ashe, J.B.

1976-01-01

A nucleonic device is described for measuring the moisture content of bulk materials using a radioisotopic fast-neutron source such as lithium-7 admixed with an alpha-particle emitter such as americium-241 as a means of minimizing the thickness of the layer of bulk material required proximate to the moisture sensor for a neutron-reflection moisture gauge for proper operation of said gauge. Minimization of the required thickness of the bulk material permits use of a neutron-reflection moisture gauge for measurements of bulk materials on lightly-loaded belts and other types of conveyors where measurements have previously been impracticable

Measurement of the Microwave Refractive Index of Materials Based on Parallel Plate Waveguides

Science.gov (United States)

Zhao, F.; Pei, J.; Kan, J. S.; Zhao, Q.

2017-12-01

An electrical field scanning apparatus based on a parallel plate waveguide method is constructed, which collects the amplitude and phase matrices as a function of the relative position. On the basis of such data, a method for calculating the refractive index of the measured wedge samples is proposed in this paper. The measurement and calculation results of different PTFE samples reveal that the refractive index measured by the apparatus is substantially consistent with the refractive index inferred with the permittivity of the sample. The proposed refractive index calculation method proposed in this paper is a competitive method for the characterization of the refractive index of materials with positive refractive index. Since the apparatus and method can be used to measure and calculate arbitrary direction of the microwave propagation, it is believed that both of them can be applied to the negative refractive index materials, such as metamaterials or “left-handed” materials.

Design of solar drying-plant for bulk material drying

Directory of Open Access Journals (Sweden)

Peter Horbaj

2008-11-01

Full Text Available A generally well-known high energy requirement for technological processes of drying and the fact that the world’s supplyof the conventional energy sources has considerably decreased are the decisive factors forcing us to look for some new, if possible,renewable energy sources for this process by emphasising their environmental reliability. One of the possibilities how to replace, atleast partly, the conventional energy sources – heat in a drying process is solar energy.Air-drying of bulk materials usually has a series of disadvantages such as time expenditure, drying defects in the bulk materialand inadequate final moisture content. A method that obviates or reduces the disadvantages of air-drying and, at the same time, reducesthe costs of kiln drying, is drying with solar heat. Solar energy can replace a large part of this depletable energy since solar energy cansupply heat at the temperatures most often used to dry bulk material. Solar drying-plant offer an attractive solution.

Characterisation of ferroelectric bulk materials and thin films

CERN Document Server

Cain, Markys G

2014-01-01

This book presents a comprehensive review of the most important methods used in the characterisation of piezoelectric, ferroelectric and pyroelectric materials. It covers techniques for the analysis of bulk materials and thick and thin film materials and devices. There is a growing demand by industry to adapt and integrate piezoelectric materials into ever smaller devices and structures. Such applications development requires the joint development of reliable, robust, accurate and - most importantly - relevant and applicable measurement and characterisation methods and models. In the past f

"Peak-tracking chip" (PTC) for bulk refractive index sensing and bioarray sensing

KAUST Repository

Bougot-Robin, Kristelle; Austin, H. Robert; Benisty, Henri; Hsing, I-Ming; Kodzius, Rimantas; Li, Shunbo; Wen, Weijia; Zhang, Yinghua

2013-01-01

Resonant techniques are of wide interest to detect variation of effective refractive index at a chip surface. Both Surface Plasmon Resonance (SPR) and dielectric resonant waveguide (RWGs) can be exploited. Through their design, RWGs allow more flexibility (size of the biomolecule to detect, detection angle…). Using specially designed RWG “Peak-tracking chip”, we propose to use spatial information from a simple monochromatic picture as a new label-free bioarray technique. We discuss robustness, sensitivity, multiplex detection, fluidic integration of the technique and illustrate it through bulk refractive index sensing as well as specific recognition of DNA fragment from gyrase A.

"Peak-tracking chip" (PTC) for bulk refractive index sensing and bioarray sensing

KAUST Repository

Bougot-Robin, Kristelle

2013-10-20

Resonant techniques are of wide interest to detect variation of effective refractive index at a chip surface. Both Surface Plasmon Resonance (SPR) and dielectric resonant waveguide (RWGs) can be exploited. Through their design, RWGs allow more flexibility (size of the biomolecule to detect, detection angle…). Using specially designed RWG “Peak-tracking chip”, we propose to use spatial information from a simple monochromatic picture as a new label-free bioarray technique. We discuss robustness, sensitivity, multiplex detection, fluidic integration of the technique and illustrate it through bulk refractive index sensing as well as specific recognition of DNA fragment from gyrase A.

Delignified and Densified Cellulose Bulk Materials with Excellent Tensile Properties for Sustainable Engineering.

Science.gov (United States)

Frey, Marion; Widner, Daniel; Segmehl, Jana S; Casdorff, Kirstin; Keplinger, Tobias; Burgert, Ingo

2018-02-07

Today's materials research aims at excellent mechanical performance in combination with advanced functionality. In this regard, great progress has been made in tailoring the materials by assembly processes in bottom-up approaches. In the field of wood-derived materials, nanocellulose research has gained increasing attention, and materials with advanced properties were developed. However, there are still unresolved issues concerning upscaling for large-scale applications. Alternatively, the sophisticated hierarchical scaffold of wood can be utilized in a top-down approach to upscale functionalization, and one can profit at the same time from its renewable nature, CO 2 storing capacity, light weight, and good mechanical performance. Nevertheless, for bulk wood materials, a wider multipurpose industrial use is so far impeded by concerns regarding durability, natural heterogeneity as well as limitations in terms of functionalization, processing, and shaping. Here, we present a novel cellulose bulk material concept based on delignification and densification of wood resulting in a high-performance material. A delignification process using hydrogen peroxide and acetic acid was optimized to delignify the entire bulk wooden blocks and to retain the highly beneficial structural directionality of wood. In a subsequent step, these cellulosic blocks were densified in a process combining compression and lateral shear to gain a very compact cellulosic material with entangled fibers while retaining unidirectional fiber orientation. The cellulose bulk materials obtained by different densification protocols were structurally, chemically, and mechanically characterized revealing superior tensile properties compared to native wood. Furthermore, after delignification, the cellulose bulk material can be easily formed into different shapes, and the delignification facilitates functionalization of the bioscaffold.

Low-loss negative index metamaterials for X, Ku, and K microwave bands

Directory of Open Access Journals (Sweden)

David A. Lee

2015-04-01

Full Text Available Low-loss, negative-index of refraction metamaterials were designed and tested for X, Ku, and K microwave frequency bands. An S-shaped, split-ring resonator was used as a unit cell to design homogeneous slabs of negative-index metamaterials. Then, the slabs of metamaterials were cut unto prisms to measure experimentally the negative index of refraction of a plane electromagnetic wave. Theoretical simulations using High-Frequency Structural Simulator, a finite element equation solver, were in good agreement with experimental measurements. The negative index of refraction was retrieved from the angle- and frequency-dependence of the transmitted intensity of the microwave beam through the metamaterial prism and compared well to simulations; in addition, near-field electromagnetic intensity mapping was conducted with an infrared camera, and there was also a good match with the simulations for expected frequency ranges for the negative index of refraction.

Hygroscopicity and bulk thermal expansion in Y2W3O12

International Nuclear Information System (INIS)

Sumithra, S.; Umarji, A.M.

2005-01-01

Negative thermal expansion material, Y 2 W 3 O 12 has been synthesized by the solid-state method and bulk thermal expansion of the material has been investigated from 300 to 1100 K. The material reversibly forms a trihydrate composition whose X-ray diffraction pattern can be indexed to an orthorhombic unit cell with a = 10.098(1) A, b = 13.315(3) A, c = 9.691(4) A. The cell volume of the hydrated pattern is 7% smaller than the unhydrated cell volume. According to the dilatometric studies, the material shows a 3-6% increase in the linear strain at about 400 K, which can be attributed to the removal of water. Sintering the material at 1473 K leads to large grain size of >100 μm, which results in a large hysteresis in the bulk thermal expansion behavior. Hot pressing at 1273 K under a uniaxial pressure of 25 MPa results in a fine-grained (2-5 μm) ceramic. Glazing the ceramic prevents moisture pick up and a linear thermal expansion over the entire temperature range 1100-300 K and an average linear thermal expansion co-efficient of -9.65 x 10 -6 /K is observed. The effect of water on the thermal expansion behavior of this system is discussed

Tunable negative index metamaterial using yttrium iron garnet

International Nuclear Information System (INIS)

He, Yongxue; He, Peng; Dae Yoon, Soack; Parimi, P.V.; Rachford, F.J.; Harris, V.G.; Vittoria, C.

2007-01-01

A magnetic field tunable, broadband, low-loss, negative refractive index metamaterial is fabricated using yttrium iron garnet (YIG) and a periodic array of copper wires. The tunability is demonstrated from 18 to 23 GHz under an applied magnetic field with a figure of merit of 4.2 GHz/kOe. The tuning bandwidth is measured to be 5 GHz compared to 0.9 GHz for fixed field. We measure a minimum insertion loss of 4 dB (or 5.7 dB/cm) at 22.3 GHz. The measured negative refractive index bandwidth is 0.9 GHz compared to 0.5 GHz calculated by the transfer function matrix theory and 1 GHz calculated by finite element simulation

All-angle negative refraction and active flat lensing of ultraviolet light.

Science.gov (United States)

Xu, Ting; Agrawal, Amit; Abashin, Maxim; Chau, Kenneth J; Lezec, Henri J

2013-05-23

Decades ago, Veselago predicted that a material with simultaneously negative electric and magnetic polarization responses would yield a 'left-handed' medium in which light propagates with opposite phase and energy velocities--a condition described by a negative refractive index. He proposed that a flat slab of left-handed material possessing an isotropic refractive index of -1 could act like an imaging lens in free space. Left-handed materials do not occur naturally, and it has only recently become possible to achieve a left-handed response using metamaterials, that is, electromagnetic structures engineered on subwavelength scales to elicit tailored polarization responses. So far, left-handed responses have typically been implemented using resonant metamaterials composed of periodic arrays of unit cells containing inductive-capacitive resonators and conductive wires. Negative refractive indices that are isotropic in two or three dimensions at microwave frequencies have been achieved in resonant metamaterials with centimetre-scale features. Scaling the left-handed response to higher frequencies, such as infrared or visible, has been done by shrinking critical dimensions to submicrometre scales by means of top-down nanofabrication. This miniaturization has, however, so far been achieved at the cost of reduced unit-cell symmetry, yielding a refractive index that is negative along only one axis. Moreover, lithographic scaling limits have so far precluded the fabrication of resonant metamaterials with left-handed responses at frequencies beyond the visible. Here we report the experimental implementation of a bulk metamaterial with a left-handed response to ultraviolet light. The structure, based on stacked plasmonic waveguides, yields an omnidirectional left-handed response for transverse magnetic polarization characterized by a negative refractive index. By engineering the structure to have a refractive index close to -1 over a broad angular range, we achieve Veselago

Integration of bulk piezoelectric materials into microsystems

Science.gov (United States)

Aktakka, Ethem Erkan

Bulk piezoelectric ceramics, compared to deposited piezoelectric thin-films, provide greater electromechanical coupling and charge capacity, which are highly desirable in many MEMS applications. In this thesis, a technology platform is developed for wafer-level integration of bulk piezoelectric substrates on silicon, with a final film thickness of 5-100microm. The characterized processes include reliable low-temperature (200°C) AuIn diffusion bonding and parylene bonding of bulk-PZT on silicon, wafer-level lapping of bulk-PZT with high-uniformity (+/-0.5microm), and low-damage micro-machining of PZT films via dicing-saw patterning, laser ablation, and wet-etching. Preservation of ferroelectric and piezoelectric properties is confirmed with hysteresis and piezo-response measurements. The introduced technology offers higher material quality and unique advantages in fabrication flexibility over existing piezoelectric film deposition methods. In order to confirm the preserved bulk properties in the final film, diaphragm and cantilever beam actuators operating in the transverse-mode are designed, fabricated and tested. The diaphragm structure and electrode shapes/sizes are optimized for maximum deflection through finite-element simulations. During tests of fabricated devices, greater than 12microm PP displacement is obtained by actuation of a 1mm2 diaphragm at 111kHz with integration of a 50-80% efficient power management IC, which incorporates a supply-independent bias circuitry, an active diode for low-dropout rectification, a bias-flip system for higher efficiency, and a trickle battery charger. The overall system does not require a pre-charged battery, and has power consumption of <1microW in active-mode (measured) and <5pA in sleep-mode (simulated). Under lg vibration at 155Hz, a 70mF ultra-capacitor is charged from OV to 1.85V in 50 minutes.

Bulk Material Based Thermoelectric Energy Harvesting for Wireless Sensor Applications

International Nuclear Information System (INIS)

Wang, W S; Magnin, W; Wang, N; Hayes, M; O'Flynn, B; O'Mathuna, C

2011-01-01

The trend towards smart building and modern manufacturing demands ubiquitous sensing in the foreseeable future. Self-powered Wireless sensor networks (WSNs) are essential for such applications. This paper describes bulk material based thermoelectric generator (TEG) design and implementation for WSN. A 20cm 2 Bi 0.5 Sb 1.5 Te 3 based TEG was created with optimized configuration and generates 2.7mW in typical condition. A novel load matching method is used to maximize the power output. The implemented power management module delivers 651μW to WSN in 50 deg. C. With average power consumption of Tyndall WSN measured at 72μW, feasibility of utilizing bulk material TEG to power WSN is demonstrated.

Nuclear techniques for bulk and surface analysis of materials

International Nuclear Information System (INIS)

D'Agostino, M.D.; Kamykowski, E.A.; Kuehne, F.J.; Padawer, G.M.; Schneid, E.J.; Schulte, R.L.; Stauber, M.C.; Swanson, F.R.

1978-01-01

A review is presented summarizing several nondestructive bulk and surface analysis nuclear techniques developed in the Grumman Research Laboratories. Bulk analysis techniques include 14-MeV-neutron activation analysis and accelerator-based neutron radiography. The surface analysis techniques include resonant and non-resonant nuclear microprobes for the depth profile analysis of light elements (H, He, Li, Be, C, N, O and F) in the surface of materials. Emphasis is placed on the description and discussion of the unique nuclear microprobe analytical capacibilities of immediate importance to a number of current problems facing materials specialists. The resolution and contrast of neutron radiography was illustrated with an operating heat pipe system. The figure shows that the neutron radiograph has a resolution of better than 0.04 cm with sufficient contrast to indicate Freon 21 on the inner capillaries of the heat pipe and pooling of the liquid at the bottom. (T.G.)

Bulk nanoscale materials in steel products

International Nuclear Information System (INIS)

Chehab, B; Wang, X; Masse, J-P; Zurob, H; Embury, D; Bouaziz, O

2010-01-01

Although a number of nanoscale metallic materials exhibit interesting mechanical properties the fabrication paths are often complex and difficult to apply to bulk structural materials. However a number of steels which exhibit combinations of plasticity and phase transitions can be deformed to produce ultra high strength levels in the range 1 to 3 GPa. The resultant high stored energy and complex microstructures allow new nanoscale structures to be produced by combinations of recovery and recrystallisation. The resultant structures exhibit totally new combinations of strength and ductility to be achieved. In specific cases this also enables both the nature of the grain boundary structure and the spatial variation in structure to be controlled. In this presentation both the detailed microstructural features and their relation to the strength, work-hardening capacity and ductility will be discussed for a number of martensitic and austenitic steels.

Purity Evaluation of Bulk Single Wall Carbon Nanotube Materials

International Nuclear Information System (INIS)

Dettlaff-Weglikowska, U.; Hornbostel, B.; Cech, J.; Roth, S.; Wang, J.; Liang, J.

2005-01-01

We report on our experience using a preliminary protocol for quality control of bulk single wall carbon nanotube (SWNT) materials produced by the electric arc-discharge and laser ablation method. The first step in the characterization of the bulk material is mechanical homogenization. Quantitative evaluation of purity has been performed using a previously reported procedure based on solution phase near-infrared spectroscopy. Our results confirm that this method is reliable in determining the nanotube content in the arc-discharge sample containing carbonaceous impurities (amorphous carbon and graphitic particles). However, the application of this method to laser ablation samples gives a relative purity value over 100 %. The possible reason for that might be different extinction coefficient meaning different oscillator strength of the laser ablation tubes. At the present time, a 100 % pure reference sample of laser ablation SWNT is not available, so we chose to adopt the sample showing the highest purity as a new reference sample for a quantitative purity evaluation of laser ablation materials. The graphitic part of the carbonaceous impurities has been estimated using X-ray diffraction of 1:1 mixture of nanotube material and C60 as an internal reference. To evaluate the metallic impurities in the as prepared and homogenized carbon nanotube soot inductive coupled plasma (ICP) has been used

Large-scale Homogenization of Bulk Materials in Mammoth Silos

NARCIS (Netherlands)

Schott, D.L.

2004-01-01

This doctoral thesis concerns the large-scale homogenization of bulk materials in mammoth silos. The objective of this research was to determine the best stacking and reclaiming method for homogenization in mammoth silos. For this purpose a simulation program was developed to estimate the

Lossless acoustic half-bipolar cylindrical cloak with negative-index metamaterial

Science.gov (United States)

Lee, Yong Y.; Ahn, Doyeol

2018-05-01

A lossless acoustic half-bipolar cylindrical cloak that has an exposed bottom is considered. Here, we show that a cloak that includes a complementary region including a negative-index medium inside of the cloaking shell works in the illumination direction independently even in the presence of the exposed bottom of the structure. This is due to the fact that the phase velocity of the wave in the normal direction can be cancelled in the presence of a boundary containing a negative-index medium that reduces scattering significantly.

Belt conveyors for bulk materials. 6th ed.

Energy Technology Data Exchange (ETDEWEB)

NONE

2007-07-01

The 16 chapters are entitled: Belt conveyor general applications economics; Design considerations; Characteristics and conveyability of bulk materials; Capacities, belt widths and speeds; Belt conveyor idlers; Belt tension and power engineering; Belt selection; Pulleys and shafts; Curves; Steep angle conveying; Belt cleaners and accessories; Transfer points; Conveyor motor drives and controls; Operation, maintenance and safety; Belt takeups; and Emerging technologies. 6 apps.

Porous 3D graphene-based bulk materials with exceptional high surface area and excellent conductivity for supercapacitors

Science.gov (United States)

Zhang, Long; Zhang, Fan; Yang, Xi; Long, Guankui; Wu, Yingpeng; Zhang, Tengfei; Leng, Kai; Huang, Yi; Ma, Yanfeng; Yu, Ao; Chen, Yongsheng

2013-01-01

Until now, few sp2 carbon materials simultaneously exhibit superior performance for specific surface area (SSA) and electrical conductivity at bulk state. Thus, it is extremely important to make such materials at bulk scale with those two outstanding properties combined together. Here, we present a simple and green but very efficient approach using two standard and simple industry steps to make such three-dimensional graphene-based porous materials at the bulk scale, with ultrahigh SSA (3523 m2/g) and excellent bulk conductivity. We conclude that these materials consist of mainly defected/wrinkled single layer graphene sheets in the dimensional size of a few nanometers, with at least some covalent bond between each other. The outstanding properties of these materials are demonstrated by their superior supercapacitor performance in ionic liquid with specific capacitance and energy density of 231 F/g and 98 Wh/kg, respectively, so far the best reported capacitance performance for all bulk carbon materials. PMID:23474952

Displacement per atom profile in carbon nanotube bulk material under gamma irradiation

International Nuclear Information System (INIS)

Leyva, A.; Pinnera, I.; Leyva, D.; Cruz, C.; Abreu, Y.

2011-01-01

Taking into account the physical properties and the displacement threshold energy values reported in literature for C atoms in single and multiple walled carbon nanotubes, the effective atomic displacement cross-section in carbon nanotube bulk materials exposed to the gamma rays were calculated. Then, using the mathematical simulation of photons and particles transport in the matter, energy fluxes distribution of electrons and positrons within the irradiated object were also calculated. Finally, considering both results, the atomic displacement damage profiles inside the analyzed carbon nanotube bulk materials were determined. (Author)

A Miniaturized Antenna with Negative Index Metamaterial Based on Modified SRR and CLS Unit Cell for UWB Microwave Imaging Applications

Directory of Open Access Journals (Sweden)

Md. Moinul Islam

2015-01-01

Full Text Available A miniaturized antenna employing a negative index metamaterial with modified split-ring resonator (SRR and capacitance-loaded strip (CLS unit cells is presented for Ultra wideband (UWB microwave imaging applications. Four left-handed (LH metamaterial (MTM unit cells are located along one axis of the antenna as the radiating element. Each left-handed metamaterial unit cell combines a modified split-ring resonator (SRR with a capacitance-loaded strip (CLS to obtain a design architecture that simultaneously exhibits both negative permittivity and negative permeability, which ensures a stable negative refractive index to improve the antenna performance for microwave imaging. The antenna structure, with dimension of 16 × 21 × 1.6 mm3, is printed on a low dielectric FR4 material with a slotted ground plane and a microstrip feed. The measured reflection coefficient demonstrates that this antenna attains 114.5% bandwidth covering the frequency band of 3.4–12.5 GHz for a voltage standing wave ratio of less than 2 with a maximum gain of 5.16 dBi at 10.15 GHz. There is a stable harmony between the simulated and measured results that indicate improved nearly omni-directional radiation characteristics within the operational frequency band. The stable surface current distribution, negative refractive index characteristic, considerable gain and radiation properties make this proposed negative index metamaterial antenna optimal for UWB microwave imaging applications.

75 FR 34573 - Bulk Solid Hazardous Materials: Harmonization With the International Maritime Solid Bulk Cargoes...

Science.gov (United States)

2010-06-17

... reduced iron (DRI) as briquettes molded at a temperature of 650 [deg]C or higher that have a density of 5... temperature of 650 [deg]C or higher or had a density of 5.0 g/cm[sup3] or greater. In this proposed rule, we... bulk materials of Hazard Classes 4 through 9. c. One comment recommended that a DCM be required for...

A generalized cost Malmquist index in DEA for DMUs with negative data

Directory of Open Access Journals (Sweden)

Ghasem Tohidi

2014-10-01

Full Text Available In some data envelopment analysis (DEA applications, some inputs of DMUs have negative values with positive cost. This paper generalizes the global cost Malmquist productivity index to compare the productivity of different DMUs with negative inputs in any two periods of times under variable returns to scale (VRS technology, and then the generalized index is decomposed to several components. The obtained components are computed using the nonparametric linear programming models, known as DEA. To illustrate the generalized index and its components, a numerical example at three successive periods of time is given.

Textile inspired flexible metamaterial with negative refractive index

Science.gov (United States)

Burgnies, L.; Lheurette, É.; Lippens, D.

2015-04-01

This work introduces metallo-dielectric woven fabric as a metamaterial for phase-front manipulation. Dispersion diagram as well as effective medium parameters retrieved from reflection and transmission coefficients point out negative values of refractive index. By numerical simulations, it is evidenced that a pair of meandered metallic wires, arranged in a top to bottom configuration, can yield to a textile metamaterial with simultaneously negative permittivity and permeability. While the effective negative permittivity stems from the metallic grid arrangement, resonating current loop resulting from the top to bottom configuration of two meandered metallic wires in near proximity produces magnetic activity with negative permeability. By adjusting the distance between pairs of metallic wires, the electric plasma frequency can be shifted to overlap the magnetic resonance. Finally, it is shown that the woven metamaterial is insensitive to the incident angle up to around 60°.

Measurement of particulate concentrations produced during bulk material handling at the Tarragona harbor

Energy Technology Data Exchange (ETDEWEB)

Artinano, B.; Gomez-Moreno, F.J.; Pujadas, M.; Moreno, N.; Alastuey, A.; Querol, X.; Martin, F.; Guerra, A.; Luaces, J.A.; Basora, J. [CIEMAT, Madrid (Spain)

2007-09-15

Bulk material handling can be a significant source of particles in harbor areas. The atmospheric impact of a number of loading/unloading activities of diverse raw materials has been assessed from continuous measurements of ambient particle concentrations recorded close to the emission sources. Two experimental campaigns have been carried out in the Tarragona port to document the impact of specific handling operations and bulk materials. Dusty bulk materials such as silica-manganese powder, tapioca, coal, clinker and lucerne were dealt with during the experiments. The highest impacts on ambient particle concentrations were recorded during handling of clinker. For this material and silica-manganese powder, high concentrations were recorded in the fine grain size ({lt}2.5 {mu}m). The lowest impacts on particulate matter concentrations were recorded during handling of tapioca and lucerne, mainly in the coarse grain size (2-5-10 {mu} m). The effectiveness of several emission abatement measures, such as ground watering to diminish coal particle resuspension, was demonstrated to reduce ambient concentrations by up to two orders of magnitude. The importance of other good practices in specific handling operations, such as controlling the height of the shovel discharge, was also evidenced by these experiments. The results obtained can be further utilized as a useful experimental database for emission factor estimations.

Hazard index for underground toxic material

International Nuclear Information System (INIS)

Smith, C.F.; Cohen, J.J.; McKone, T.E.

1980-06-01

To adequately define the problem of waste management, quantitative measures of hazard must be used. This study reviews past work in the area of hazard indices and proposes a geotoxicity hazard index for use in characterizing the hazard of toxic material buried underground. Factors included in this index are: an intrinsic toxicity factor, formulated as the volume of water required for dilution to public drinking-water levels; a persistence factor to characterize the longevity of the material, ranging from unity for stable materials to smaller values for shorter-lived materials; an availability factor that relates the transport potential for the particular material to a reference value for its naturally occurring analog; and a correction factor to accommodate the buildup of decay progeny, resulting in increased toxicity

Hazard index for underground toxic material

Energy Technology Data Exchange (ETDEWEB)

Smith, C.F.; Cohen, J.J.; McKone, T.E.

1980-06-01

To adequately define the problem of waste management, quantitative measures of hazard must be used. This study reviews past work in the area of hazard indices and proposes a geotoxicity hazard index for use in characterizing the hazard of toxic material buried underground. Factors included in this index are: an intrinsic toxicity factor, formulated as the volume of water required for dilution to public drinking-water levels; a persistence factor to characterize the longevity of the material, ranging from unity for stable materials to smaller values for shorter-lived materials; an availability factor that relates the transport potential for the particular material to a reference value for its naturally occurring analog; and a correction factor to accommodate the buildup of decay progeny, resulting in increased toxicity.

Bulk Building Material Characterization and Decontamination Using a Concrete Floor and Wall Contamination Profiling Technology

International Nuclear Information System (INIS)

Aggarwal, S.; Charters, G.; Blauvelt, D.

2002-01-01

The concrete profiling technology, RadPro(trademark) has four major components: a drill with a specialized cutting and sampling head, drill bits, a sample collection unit and a vacuum pump. The equipment in conjunction with portable radiometric instrumentation produces a profile of radiological or chemical contamination through the material being studied. The drill head is used under hammer action to penetrate hard surfaces. This causes the bulk material to be pulverized as the drill travels through the radioactive media efficiently transmitting to the sampling unit a representative sample of powdered bulk material. The profiling equipment is designed to sequentially collect all material from the hole. The bulk material samples are continuously retrieved by use of a specially designed vacuumed sample retrieval unit that prevents cross contamination of the clean retrieved samples. No circulation medium is required with this profiling process; therefore, the only by-product from drilling is the sample. The data quality, quantity, and representativeness may be used to produce an activity profile from the hot spot surface into the bulk building material. The activity data obtained during the profiling process is reduced and transferred to building drawings as part of a detailed report of the radiological problem. This activity profile may then be expanded to ultimately characterize the facility and expedite waste segregation and facility closure at a reduced cost and risk

Dust prevention in bulk material transportation and handling

Science.gov (United States)

Kirichenko, A. V.; Kuznetsov, A. L.; Pogodin, V. A.

2017-10-01

The environmental problem of territory and atmosphere pollution caused by transportation and handling of dust-generating bulk cargo materials is quite common for the whole world. The reducing of weight of fine class coal caused by air blowing reaches the level of 0.5-0.6 t per railcar over the 500 km transportation distance, which is equal to the loss of 1 % of the total weight. The studies showed that all over the country in the process of the railroad transportation, the industry loses 3-5 metric tonnes of coal annually. There are several common tactical measurers to prevent dust formation: treating the dust-producing materials at dispatch point with special liquid solutions; watering the stacks and open handling points of materials; frequent dust removing and working area cleaning. Recently there appeared several new radical measures for pollution prevention in export of ore and coal materials via sea port terminals, specifically: wind-dust protection screens, the container cargo handling system of delivery materials to the hold of the vessels. The article focuses on the discussion of these measures.

Ultra-low thermal expansion realized in giant negative thermal expansion materials through self-compensation

Science.gov (United States)

Shen, Fei-Ran; Kuang, Hao; Hu, Feng-Xia; Wu, Hui; Huang, Qing-Zhen; Liang, Fei-Xiang; Qiao, Kai-Ming; Li, Jia; Wang, Jing; Liu, Yao; Zhang, Lei; He, Min; Zhang, Ying; Zuo, Wen-Liang; Sun, Ji-Rong; Shen, Bao-Gen

2017-10-01

Materials with zero thermal expansion (ZTE) or precisely tailored thermal expansion are in urgent demand of modern industries. However, the overwhelming majority of materials show positive thermal expansion. To develop ZTE or negative thermal expansion (NTE) materials as compensators has become an important challenge. Here, we present the evidence for the realization of ultra-low thermal expansion in Mn-Co-Ge-In particles. The bulk with the Ni2In-type hexagonal structure undergoes giant NTE owing to a martensitic magnetostructural transition. The major finding is that the thermal expansion behavior can be totally controlled by modulating the crystallinity degree and phase transition from atomic scale. Self-compensation effect leads to ultra-low thermal expansion with a linear expansion coefficient as small as +0.68 × 10-6/K over a wide temperature range around room temperature. The present study opens an avenue to reach ZTE particularly from the large class of giant NTE materials based on phase transition.

Ultra-low thermal expansion realized in giant negative thermal expansion materials through self-compensation

Directory of Open Access Journals (Sweden)

Fei-Ran Shen

2017-10-01

Full Text Available Materials with zero thermal expansion (ZTE or precisely tailored thermal expansion are in urgent demand of modern industries. However, the overwhelming majority of materials show positive thermal expansion. To develop ZTE or negative thermal expansion (NTE materials as compensators has become an important challenge. Here, we present the evidence for the realization of ultra-low thermal expansion in Mn–Co–Ge–In particles. The bulk with the Ni2In-type hexagonal structure undergoes giant NTE owing to a martensitic magnetostructural transition. The major finding is that the thermal expansion behavior can be totally controlled by modulating the crystallinity degree and phase transition from atomic scale. Self-compensation effect leads to ultra-low thermal expansion with a linear expansion coefficient as small as +0.68 × 10−6/K over a wide temperature range around room temperature. The present study opens an avenue to reach ZTE particularly from the large class of giant NTE materials based on phase transition.

A high energy microscope for local strain measurements within bulk materials

DEFF Research Database (Denmark)

Lienert, U.; Poulsen, H.F.; Martins, R.V.

2000-01-01

A novel diffraction technique for local, three dimensional strain scanning within bulk materials is presented. The technique utilizes high energy, micro-focussed synchrotron radiation which can penetrate several millimeters into typical metals. The spatial resolution can be as narrow as 1 mum...... in one dimension and in three dimensions about 5x10x100 mum(3) Bulk properties are probed non-destructively and in-situ measurements during thermo-mechanical processing are feasible. A dedicated experimental station has been constructed at the ID11 beamline of the European Synchrotron Radiation Facility...

Superhard MgB sub 2 bulk material prepared by high-pressure sintering

CERN Document Server

Ma, H A; Chen, L X; Zhu, P W; Ren, G Z; Guo, W L; Fu, X Q; Zou Guang Tian; Ren, Z A; Che, G C; Zhao, Z X

2002-01-01

Superhard MgB sub 2 bulk material with a golden metallic shine was synthesized by high-pressure sintering for 8 h at 5.5 GPa and different temperatures. Appropriate pressure and temperature conditions for synthesizing polycrystalline MgB sub 2 with high hardness were investigated. The samples were characterized by means of atomic force microscopy and x-ray diffraction. The Vickers hardness, bulk density, and electrical resistivity were measured at room temperature.

Cherenkov radiation by an electron bunch that moves in a vacuum above a left-handed material

International Nuclear Information System (INIS)

Averkov, Yu.O.; Yakovenko, V.M.

2005-01-01

Cherenkov radiation by a nonrelativistic electron bunch that moves above an interface of a vacuum-left-handed material has been investigated theoretically. The electron density of the bunch is described by a Gauss distribution. Cherenkov radiation for the frequency range where the refractive index is negative is shown to lead to simultaneous excitation of both bulk and surface electromagnetic waves over one and the same frequency range. In this case the wave vector magnitude in the plane of the interface of surface electromagnetic waves is larger than the corresponding wave vector magnitude of bulk electromagnetic waves. The energy flows in a left-handed material have been calculated. The spectral density and the radiation pattern have been investigated

Bulk Materials Analysis Using High-Energy Positron Beams

International Nuclear Information System (INIS)

Glade, S C; Asoka-Kumar, P; Nieh, T G; Sterne, P A; Wirth, B D; Dauskardt, R H; Flores, K M; Suh, D; Odette, G.R.

2002-01-01

This article reviews some recent materials analysis results using high-energy positron beams at Lawrence Livermore National Laboratory. We are combining positron lifetime and orbital electron momentum spectroscopic methods to provide electron number densities and electron momentum distributions around positron annihilation sites. Topics covered include: correlation of positron annihilation characteristics with structural and mechanical properties of bulk metallic glasses, compositional studies of embrittling features in nuclear reactor pressure vessel steel, pore characterization in Zeolites, and positron annihilation characteristics in alkali halides

Recent progress in material technology on RE-Ba-Cu-O bulk superconductors

International Nuclear Information System (INIS)

Teshima, Hidekazu; Morita, Mitsuru

2011-01-01

The current status of large-grained RE-Ba-Cu-O (RE: Y or rare earth elements) bulk superconductors with excellent superconducting properties is described. Gd-Ba-Cu-O bulk superconductors can trap a very high magnetic field even if they are melt-processed in air. Although the electromagnetic force caused by the trapped field is larger for a larger sample and may break the sample, a large sample of Gd-Ba-Cu-O 46 mm in diameter has the potential of trapped magnetic fields greater than 10 T at around 40 K. In addition, single-grained bulk superconductors as large as 150 mm can be obtained using the RE compositional gradient method. Dy-Ba-Cu-O is an ideal material for current leads because it has low thermal conductivity and high critical current density at 77 K in high magnetic fields. Eu-Ba-Cu-O has low magnetic permeability, and is therefore suitable for bulk NMR applications. Progress in machining technology has made possible various bulk superconductors with complicated shapes such as coils, leading to small and strong electromagnets by stacking several coil-shaped bulk superconductors together. (author)

Shear bond strength of bulk-fill and nano-restorative materials to dentin.

Science.gov (United States)

Colak, Hakan; Ercan, Ertugrul; Hamidi, Mehmet Mustafa

2016-01-01

Bulk-fill composite materials are being developed for preparation depths of up to 4 mm in an effort to simplify and improve the placement of direct composite posterior restorations. The aim of our study was to compare shear-bond strength of bulk-fill and conventional posterior composite resins. In this study, 60 caries free extracted human molars were used and sectioned parallel to occlusal surface to expose midcoronal dentin. The specimens were randomly divided into four groups. Total-etch dentine bonding system (Adper Scotchbond 1XT, 3M ESPE) was applied to dentin surface in all the groups to reduce variability in results. Then, dentine surfaces covered by following materials. Group I: SonicFill Bulk-Fill, Group II: Tetric EvoCeram (TBF), Group III: Herculite XRV Ultra, and Group IV: TBF Bulk-Fill, 2 mm × 3 mm cylindrical restorations were prepared by using application apparatus. Shear bond testing was measured by using a universal testing machine. Kruskal-Wallis and Mann-Whitney U-tests were performed to evaluate the data. The highest value was observed in Group III (14.42 ± 4.34) and the lowest value was observed in Group IV (11.16 ± 2.76) and there is a statistically significant difference between these groups (P = 0.046). However, there is no statistically significant difference between the values of other groups. In this study, Group III was showed higher strength values. There is a need for future studies about long-term bond strength and clinical success of these adhesive and bulk-fill systems.

Optical characteristics of novel bulk and nanoengineered laser host materials

Science.gov (United States)

Prasad, Narasimha S.; Sova, Stacey; Kelly, Lisa; Bevan, Talon; Arnold, Bradley; Cooper, Christopher; Choa, Fow-Sen; Singh, N. B.

2018-02-01

The hexagonal apatite single crystals have been investigated for their applications as laser host materials. Czochralksi and flux growth methods have been utilized to obtain single crystals. For low temperature processing (useful properties as laser hosts and bone materials. Calcium lanthanum silicate (Nd-doped) and lanthanum aluminate material systems were studied in detail. Nanoengineered calcium and lanthanum based silicates were synthesized by a solution method and their optical and morphological characteristics were compared with Czochralski grown bulk hydroxyapatite single crystals. Materials were evaluated by absorbance, fluorescence and Raman characteristics. Neodymium, iron and chromium doped crystals grown by a solution method showed weak but similar optical properties to that of Czochralski grown single crystals.

Bulk density, cone index and water content relations for some Ghanian soils

International Nuclear Information System (INIS)

Agodzo, S.K.; Adama, I.

2004-01-01

Correlations were established between water content θ, bulk density ρ and cone index Δ for 4 Ghanaian soils, namely, Kumasi, Akroso, Nta and Offin series. The relationship between Δ and θ is in the form Δ = a θ 2 + b θ + c, where the correlation coefficients r 2 for the various soils were found to be very high. Similarly, Δ - ρ relationships were linear but the correlations got weaker with increasing sand content of the soil, as expected. Soil sample sizes and compaction procedures did not conform to standard procedures, yet the results did not deviate from what pertains when standard procedures are used. (author)

ABOUT INDEX EVALUATION OF MATERIAL RESOURCE SUPPLIER SELECTION

OpenAIRE

V. A. Skochinskaya

2008-01-01

The paper analyzes existing methods for evaluation of material resource supplier selection. It shows advantages and shortcomings of the present evaluation systems. The necessity for application of an index evaluation is justified in the paper. The paper contains rating (index) evaluation for material resource supplier selection which is based on the application of quantitative (index) tool instead of an expert (numerical) evaluation. 

ABOUT INDEX EVALUATION OF MATERIAL RESOURCE SUPPLIER SELECTION

Directory of Open Access Journals (Sweden)

V. A. Skochinskaya

2008-01-01

Full Text Available The paper analyzes existing methods for evaluation of material resource supplier selection. It shows advantages and shortcomings of the present evaluation systems. The necessity for application of an index evaluation is justified in the paper. The paper contains rating (index evaluation for material resource supplier selection which is based on the application of quantitative (index tool instead of an expert (numerical evaluation. 

On-line analysis of bulk materials using pulsed neutron interrogation

International Nuclear Information System (INIS)

Lebrun, P.; Tourneur, P. Le; Poumarede, B.; Bach, P.; Moeller, H.

1999-01-01

On the basis of our joint experience in neutronics for SODERN and in cement plant engineering for KRUPP POLYSIUS, we have developed a new on-line bulk materials analyser for the cement industry. This equipment includes a pulsed neutron generator GENIE 16, some gamma ray and neutron detectors, specially designed electronics with high counting rate, software delivering the mean elemental composition of raw material, and adequate shielding. This material is transported through the equipment on a conveyor belt, the size of which is adapted to the requirements. This paper briefly describes the equipment and some results, as obtained in dynamic test from a demonstrator installed in Germany

On-line analysis of bulk materials using pulsed neutron interrogation

Science.gov (United States)

Lebrun, P.; Tourneur, P. Le; Poumarede, B.; Möller, H.; Bach, P.

1999-06-01

On the basis of our joint experience in neutronics for SODERN and in cement plant engineering for KRUPP POLYSIUS, we have developed a new on-line bulk materials analyser for the cement industry. This equipment includes a pulsed neutron generator GENIE 16, some gamma ray and neutron detectors, specially designed electronics with high counting rate, software delivering the mean elemental composition of raw material, and adequate shielding. This material is transported through the equipment on a conveyor belt, the size of which is adapted to the requirements. This paper briefly describes the equipment and some results, as obtained in dynamic test from a demonstrator installed in Germany.

Development of a novel filling technique. Loading bulk particulate materials into tankers or processes

Energy Technology Data Exchange (ETDEWEB)

Farnish, R.J.; Berry, R.; Bradley, M. [Greenwich Univ., Chatham Maritime, Kent (United Kingdom). Wolfson Centre for Bulk Solids Handling Technology

2008-07-01

The majority of industrial dosing or filling operations demand high filling rates and often good repeatability of discharges. For coarse, free-flowing materials the issues of obtaining a high degree of filling efficiency are substantially less challenging than for less free-flowing or cohesive bulk particulates. Typical equipment arrangements for achieving a controlled (often dual rate) discharge of particles into a relatively small capacity container (flask, sack or big bag) often rely on either a mechanical extraction of material from a buffer (screw feeders) or the manipulation of a constricting arrangement to achieve a turn down in discharge rate. Where less freeflowing or very fine particles are being handled, the introduction of air into the powder is invariably used to modify the bulk condition of the material to a condition where discharge can be initiated and supported (typical examples being powder feed to an impeller packer, or discharge of powder into a rail or road wagon). This article will therefore report on some recent research that has been undertaken by The Wolfson Centre for Bulk Solids Handling Technology, University of Greenwich. (orig.)

O the Determination of the Complex Refractive Index of Powdered Materials in the 9 TO 11 Micrometer Spectral Region Utilizing AN Attenuated Total Reflectance Technique.

Science.gov (United States)

Gillespie, James Bryce

1982-03-01

A specific method of determining the complex refractive index of powdered materials using attenuated total reflectance (ATR) spectroscopy was investigated. A very precise laser/goniometric ATR system was assembled and applied to powdered samples of carbon blacks, graphite, kaolin clay, quartz, calcite, and sodalime glass beads. The reflectivity data fell into two categories: (1) data representative of a medium having a unique effective refractive index and (2) data representative of a scattering medium having no unique refractive index. Data of the first kind were obtained from all the carbon black, graphite, and kaolin clay samples. The Fahrenfort-Visser solution of the Fresnel equations was applied to the goniometric reflectivity data for these samples to obtain the complex refractive index of these effective media. The complex refractive index obtained in this manner is not that of the bulk material but is instead a value which may be related to the bulk material value through some refractive index mixing rule. A systematic experiment using carbon black of particle size 0.0106 mm diameter was conducted to determine the applicability of several mixture rules for the volume packing fraction range of .2 to .6 which is most often encountered. The Bruggemann effective medium theory produced credible results while the Lorentz-Lorenz rule and the empirical Biot-Arago rule were invalid in this volume packing region. The Bruggemann rule was applied to lampblack, Mogul-L carbon black, graphite, and kaolin clay to obtain the complex refractive indices of these materials from the ATR spectroscopy data. Goniometric reflectivity data representative of an inhomogeneous scattering medium were obtained from all the powdered quartz, powdered calcite, and sodalime glass beads samples. These samples all contained particles with diameters nearly as large as the wavelength. These data demonstrate that the ATR technique, coupled with an effective medium analysis, may be used to obtain

Nottingham Prognostic Index in Triple-Negative Breast Cancer: a reliable prognostic tool?

International Nuclear Information System (INIS)

Albergaria, André; Ricardo, Sara; Milanezi, Fernanda; Carneiro, Vítor; Amendoeira, Isabel; Vieira, Daniella; Cameselle-Teijeiro, Jorge; Schmitt, Fernando

2011-01-01

A breast cancer prognostic tool should ideally be applicable to all types of invasive breast lesions. A number of studies have shown histopathological grade to be an independent prognostic factor in breast cancer, adding prognostic power to nodal stage and tumour size. The Nottingham Prognostic Index has been shown to accurately predict patient outcome in stratified groups with a follow-up period of 15 years after primary diagnosis of breast cancer. Clinically, breast tumours that lack the expression of Oestrogen Receptor, Progesterone Receptor and Human Epidermal growth factor Receptor 2 (HER2) are identified as presenting a 'triple-negative' phenotype or as triple-negative breast cancers. These poor outcome tumours represent an easily recognisable prognostic group of breast cancer with aggressive behaviour that currently lack the benefit of available systemic therapy. There are conflicting results on the prevalence of lymph node metastasis at the time of diagnosis in triple-negative breast cancer patients but it is currently accepted that triple-negative breast cancer does not metastasize to axillary nodes and bones as frequently as the non-triple-negative carcinomas, favouring instead, a preferentially haematogenous spread. Hypothetically, this particular tumour dissemination pattern would impair the reliability of using Nottingham Prognostic Index as a tool for triple-negative breast cancer prognostication. The present study tested the effectiveness of the Nottingham Prognostic Index in stratifying breast cancer patients of different subtypes with special emphasis in a triple-negative breast cancer patient subset versus non- triple-negative breast cancer. We demonstrated that besides the fact that TNBC disseminate to axillary lymph nodes as frequently as luminal or HER2 tumours, we also showed that TNBC are larger in size compared with other subtypes and almost all grade 3. Additionally, survival curves demonstrated that these prognostic factors are

Developing bulk exchange spring magnets

Science.gov (United States)

Mccall, Scott K.; Kuntz, Joshua D.

2017-06-27

A method of making a bulk exchange spring magnet by providing a magnetically soft material, providing a hard magnetic material, and producing a composite of said magnetically soft material and said hard magnetic material to make the bulk exchange spring magnet. The step of producing a composite of magnetically soft material and hard magnetic material is accomplished by electrophoretic deposition of the magnetically soft material and the hard magnetic material to make the bulk exchange spring magnet.

Environment-oriented life cycle analysis of bulk materials, applied in solar cell systems

International Nuclear Information System (INIS)

Geelen, H.

1994-04-01

In the solar cell technology several bulk materials (glass, steel, aluminium, concrete, copper, zinc and synthetic materials) are applied intensively. By means of a life cycle analysis (LCA) the environmental effects and bottlenecks of the use of these materials is investigated in this report. Also attention is paid to the options to reduce the environmental effects of photovoltaic (PV) systems by changing processes and/or by redesign of the PV systems. Two systems are studied: solar cells, integrated in pitched roofs, and solar cells on the ground in solar cell arrays. The study is focused on the use of bulk materials in the solar module, the cables and the supporting construction. After brief introductions on the environment-oriented LCA method, the standard construction of PV modules and the principles of solar cells, an overview is given of the present and future material input for the above-mentioned PV-systems. Next, attention is paid to the energy consumption and the most important emissions of the production of the bulk materials. Based on these data three environmental effect scores of the PV systems are calculated and analyzed: the energy consumption, the greenhouse effect or global warming equivalent, and the acidifying effect or acidification equivalent. Also a fourth effect, for which the so-called environmental indicator human toxicity is defined, is described. By means of this indicator the hazardous effects for the public health can be indicated. The sum of the four indicators is a measure for the environmental profile of the roof PV-system and the ground PV-array system. Recommendations are given by which the systems and their environmental profiles can be improved. 29 figs., 50 tabs., 5 appendices, refs

Acoustic behavior of a fibrous bulk material. [Kevlar 29 sound absorber

Science.gov (United States)

Hersh, A. S.; Walker, B.

1979-01-01

A semiempirical model is presented describing the acoustic behavior of Kevlar 29, a bulk absorbing material. The model is based on an approximate solution to the one-dimensional equations representing conservation of fluctuating mass, momentum and energy. By treating the material as a momentum sink, theoretical expressions of the material complex propagation constants and characteristic impedance were derived in terms of a single constant. Evaluating the constant at a single frequency for a particular specimen, excellent agreement between prediction and measurement was achieved for a large range of sound frequencies and material porosities and thicknesses. Results show that Kevlar 29 absorbs sound efficiently even at low frequencies. This is explained in terms of a frequency dependent material phase speed.

Materials processing, pulsed field magnetization and field-pole application to propulsion motors on Gd123 bulk superconductors

International Nuclear Information System (INIS)

Izumi, M; Xu, C; Xu, Y; Morita, E; Kimura, Y; Hu, A; Ichihara, M; Murakami, M; Sakai, N; Hirabayashi, I; Sugimoto, H; Miki, M

2008-01-01

Gd123 bulk superconductor is one of the promising magnet materials. We studied the materials processing to grow high performance magnet with a doping of nano-sized metal oxides such as ZrO 2 as a candidature of pinning centre. The enhancement of the critical current density was obtained. Growth of nano-sized particles of Gd211 in addition to BaZrO 3 were observed by TEM. The formation of nano-sized particles appears a key to improve the integrated flux trapped inside the bulks and the TEM reveals an intriguing effect of the addition to the microstructure of bulk materials. Magnetization process is crucial especially for an extended machinery. Pulsed field magnetization was applied to the field-pole bulk on the rotor disk of the tested synchronous motor. The trapped flux density of 1.3 T for Gd123 bulk sample and of 60 mm diameter was reached in the limited dimension of the tested motor by a step cooling method down to 38 K with a closed-cycle condensed neon. The pulsed magnetic field was applied with a new type of split-armature coil. A large bulk of 140 mm diameter has also shown a potential flux trapping superior to other smaller specimens. The bulk magnet provides a strong magnetic field around the bulk body itself with high current density relative to a coil winding. A comparative drawing of a 'torque density' of a variety of motors which is defined as the torque divided by the volume of the motor indicates a potential advantage of bulk motor as a super permanent magnet motor

Role of phase matching in pulsed second-harmonic generation: Walk-off and phase-locked twin pulses in negative-index media

International Nuclear Information System (INIS)

Roppo, Vito; Centini, Marco; Sibilia, Concita; Bertolotti, Mario; De Ceglia, Domenico; Scalora, Michael; Akozbek, Neset; Bloemer, Mark J.; Haus, Joseph W.; Kosareva, Olga G.; Kandidov, Valery P.

2007-01-01

The present investigation is concerned with the study of pulsed second-harmonic generation under conditions of phase and group velocity mismatch, and generally low conversion efficiencies and pump intensities. In positive-index, nonmetallic materials, we generally find qualitative agreement with previous reports regarding the presence of a double-peaked second harmonic signal, which comprises a pulse that walks off and propagates at the nominal group velocity one expects at the second-harmonic frequency, and a second pulse that is 'captured' and propagates under the pump pulse. We find that the origin of the double-peaked structure resides in a phase-locking mechanism that characterizes not only second-harmonic generation, but also χ (3) processes and third-harmonic generation. The phase-locking mechanism that we describe occurs for arbitrarily small pump intensities, and so it is not a soliton effect, which usually relies on a threshold mechanism, although multicolor solitons display similar phase locking characteristics. Thus, in second harmonic generation a phase-matched component is always generated, even under conditions of material phase mismatch: This component is anomalous, because the material does not allow energy exchange between the pump and the second-harmonic beam. On the other hand, if the material is phase matched, phase locking and phase matching are indistinguishable, and the conversion process becomes efficient. We also report a similar phase-locking phenomenon in negative index materials. A spectral analysis of the pump and the generated signals reveals that the phase-locking phenomenon causes the forward moving, phase-locked second-harmonic pulse to experience the same negative index as the pump pulse, even though the index of refraction at the second-harmonic frequency is positive. Our analysis further shows that the reflected second-harmonic pulse generated at the interface and the forward-moving, phase-locked pulse appear to be part of the

Efficient Bulk Operations on Dynamic R-Trees

DEFF Research Database (Denmark)

Arge, Lars Allan; Hinrichs, Klaus; Vahrenhold, Jan

2002-01-01

In recent years there has been an upsurge of interest in spatial databases. A major issue is how to manipulate efficiently massive amounts of spatial data stored on disk in multidimensional spatial indexes (data structures). Construction of spatial indexes (bulk loading ) has been studied...... intensively in the database community. The continuous arrival of massive amounts of new data makes it important to update existing indexes (bulk updating ) efficiently. In this paper we present a simple, yet efficient, technique for performing bulk update and query operations on multidimensional indexes. We...... present our technique in terms of the so-called R-tree and its variants, as they have emerged as practically efficient indexing methods for spatial data. Our method uses ideas from the buffer tree lazy buffering technique and fully utilizes the available internal memory and the page size of the operating...

Analysis on approach of safeguards implementation at research reactor handling item count and bulk material

International Nuclear Information System (INIS)

Kim, Hyun Jo; Lee, Sung Ho; Lee, Byung Doo; Jung, Juang

2016-01-01

KiJang research reactor (KJRR) will be constructed to produce the radioisotope such as Mo-99 etc., provide the neutron transmutation doping (NTD) service of silicon, and develop the core technologies of research reactor. In this paper, the features of the process and nuclear material flow are reviewed and the material balance area (MBA) and key measurement point (KMP) are established based on the nuclear material flow. Also, this paper reviews the approach on safeguards and nuclear material accountancy at the facility level for Safeguards-by-Design at research reactor handling item count and bulk material. In this paper, MBA and KMPs are established through the analysis on facility features and major process at KJRR handling item count and bulk material. Also, this paper reviews the IAEA safeguards implementation and nuclear material accountancy at KJRR. It is necessary to discuss the safeguards approach on the fresh FM target assemblies and remaining uranium in the intermediate level liquid wastes

Analysis on approach of safeguards implementation at research reactor handling item count and bulk material

Energy Technology Data Exchange (ETDEWEB)

Kim, Hyun Jo; Lee, Sung Ho; Lee, Byung Doo; Jung, Juang [KAERI, Daejeon (Korea, Republic of)

2016-05-15

KiJang research reactor (KJRR) will be constructed to produce the radioisotope such as Mo-99 etc., provide the neutron transmutation doping (NTD) service of silicon, and develop the core technologies of research reactor. In this paper, the features of the process and nuclear material flow are reviewed and the material balance area (MBA) and key measurement point (KMP) are established based on the nuclear material flow. Also, this paper reviews the approach on safeguards and nuclear material accountancy at the facility level for Safeguards-by-Design at research reactor handling item count and bulk material. In this paper, MBA and KMPs are established through the analysis on facility features and major process at KJRR handling item count and bulk material. Also, this paper reviews the IAEA safeguards implementation and nuclear material accountancy at KJRR. It is necessary to discuss the safeguards approach on the fresh FM target assemblies and remaining uranium in the intermediate level liquid wastes.

Negative running of the spectral index, hemispherical asymmetry and the consistency of Planck with large r

International Nuclear Information System (INIS)

McDonald, John

2014-01-01

Planck favours a negative running of the spectral index, with the likelihood being dominated by low multipoles l ∼< 50 and no preference for running at higher l. A negative spectral index is also necessary for the 2- Planck upper bound on the tensor-to-scalar ratio r to be consistent with values significantly larger than 0.1. Planck has also observed a hemispherical asymmetry of the CMB power spectrum, again mostly at low multipoles. Here we consider whether the physics responsible for the hemispherical asymmetry could also account for the negative running of the spectral index and the consistency of Planck with a large value of r. A negative running of the spectral index can be generated if the hemispherical asymmetry is due to a scale- and space-dependent modulation which suppresses the CMB power spectrum at low multipoles. We show that the observed hemispherical asymmetry at low l can be generated while satisfying constraints on the asymmetry at higher l and generating a negative spectral index of the right magnitude to account for the Planck observation and to allow Planck to be consistent with a large value of r

Influence of refraction index strength on the light propagation in dielectrics material with periodic refraction index

International Nuclear Information System (INIS)

Hidayat, Arif; Latifah, Eny; Kurniati, Diana; Wisodo, Hari

2016-01-01

This study investigated the influence of refraction index strength on the light propagation in refraction index-varied dielectric material. This dielectric material served as photonic lattice. The behavior of light propagation influenced by variation of refraction index in photonic lattice was investigated. Modes of the guiding light were determined numerically using squared-operator iteration method. It was found that the greater the strength of refraction index, the smaller the guiding modes.

Specific absorption rate analysis of broadband mobile antenna with negative index metamaterial

Science.gov (United States)

Alam, Touhidul; Faruque, Mohammad Rashed Iqbal; Islam, Mohammad Tariqul

2016-03-01

This paper presents a negative index metamaterial-inspired printed mobile wireless antenna that can support most mobile applications such as GSM, UMTS, Bluetooth and WLAN frequency bands. The antenna consists of a semi-circular patch, a 50Ω microstrip feed line and metamaterial ground plane. The antenna occupies a very small space of 37 × 47 × 0.508 mm3, making it suitable for mobile wireless application. The perceptible novelty shown in this proposed antenna is that reduction of specific absorption rate using the negative index metamaterial ground plane. The proposed antenna reduced 72.11 and 75.53 % of specific absorption rate at 1.8 and 2.4 GHz, respectively.

Investigation of the spin Seebeck effect and anomalous Nernst effect in a bulk carbon material

Science.gov (United States)

Wongjom, Poramed; Pinitsoontorn, Supree

2018-03-01

Since the discovery of the spin Seebeck effect (SSE) in 2008, it has become one of the most active topics in the spin caloritronics research field. It opened up a new way to create the spin current by a combination of magnetic fields and heat. The SSE was observed in many kinds of materials including metallic, semiconductor, or insulating magnets, as well as non-magnetic materials. On the other hand, carbon-based materials have become one of the most exciting research areas recently due to its low cost, abundance and some exceptional functionalities. In this work, we have investigated the possibility of the SSE in bulk carbon materials for the first time. Thin platinum film (Pt), coated on the smoothened surface of the bulk carbon, was used as the spin detector via the inverse spin Hall effect (ISHE). The experiment for observing longitudinal SSE in the bulk carbon was set up by applying a magnetic field up to 30 kOe to the sample with the direction perpendicular to the applied temperature gradient. The induced voltage from the SSE was extracted. However, for conductive materials, e.g. carbon, the voltage signal under this set up could be a combination of the SSE and the anomalous Nernst effect (ANE). Therefore, two measurement configurations were carried out, i.e. the in-plane magnetization (IM), and the perpendicular-to-plane magnetization (PM). For the IM configuration, the SSE + ANE signals were detected where as the only ANE signal existed in the PM configuration. The results showed that there were the differences between the voltage signals from the IM and PM configurations implying the possibility of the SSE in the bulk carbon material. Moreover, it was found that the difference in the IM and PM signals was a function of the magnetic field strength, temperature difference, and measurement temperature. Although the magnitude of the possible SSE voltage in this experiment was rather low (less than 0.5 μV at 50 K), this research showed that potential of using

Amorphous silicon as high index photonic material

Science.gov (United States)

Lipka, T.; Harke, A.; Horn, O.; Amthor, J.; Müller, J.

2009-05-01

Silicon-on-Insulator (SOI) photonics has become an attractive research topic within the area of integrated optics. This paper aims to fabricate SOI-structures for optical communication applications with lower costs compared to standard fabrication processes as well as to provide a higher flexibility with respect to waveguide and substrate material choice. Amorphous silicon is deposited on thermal oxidized silicon wafers with plasma-enhanced chemical vapor deposition (PECVD). The material is optimized in terms of optical light transmission and refractive index. Different a-Si:H waveguides with low propagation losses are presented. The waveguides were processed with CMOS-compatible fabrication technologies and standard DUV-lithography enabling high volume production. To overcome the large mode-field diameter mismatch between incoupling fiber and sub-μm waveguides three dimensional, amorphous silicon tapers were fabricated with a KOH etched shadow mask for patterning. Using ellipsometric and Raman spectroscopic measurements the material properties as refractive index, layer thickness, crystallinity and material composition were analyzed. Rapid thermal annealing (RTA) experiments of amorphous thin films and rib waveguides were performed aiming to tune the refractive index of the deposited a-Si:H waveguide core layer after deposition.

Theoretical study on the electronic and optical properties of bulk and surface (001) InxGa1-xAs

Science.gov (United States)

Liu, XueFei; Ding, Zhao; Luo, ZiJiang; Zhou, Xun; Wei, JieMin; Wang, Yi; Guo, Xiang; Lang, QiZhi

2018-05-01

The optical properties of surface and bulk InxGa1-xAs materials are compared systematically first time in this paper. The band structures, density of states and optical properties including dielectric function, reflectivity, absorption coefficient, loss function and refractive index of bulk and surface InxGa1-xAs materials are investigated by first-principles based on plane-wave pseudo-potentials method within the LDA approximation. The results agree well with the available theoretical and experimental studies and indicate that the electronic and optical properties of bulk and surface InxGa1-xAs materials are much different, and the results show that the considered optical properties of the both materials vary with increasing indium composition in an opposite way. The calculations show that the optical properties of surface In0.75Ga0.25As material are unexpected to be far from the other two indium compositions of surface InxGa1-xAs materials while the optical properties of bulk InxGa1-xAs materials vary with increasing indium composition in an expected regular way.

High symmetry versus optical isotropy of a negative-index metamaterial

DEFF Research Database (Denmark)

Menzel, Christoph; Rockstuhl, Carsten; Lliew, Rumen

2010-01-01

condition since it is usually assumed that light does not resolve the spatial details of MM but experiences the properties of an effective medium, which is then optically isotropic. In this work we challenge this assumption by analyzing the isofrequency surfaces of the dispersion relation of the split cube...... in carcass negative index MM. We show that this MM is basically optically isotropic but not in the spectral domain where it exhibits negative refraction. The primary goal of this contribution is to introduce a tool that allows to probe a MM against optical isotropy....

Zinc sulfide and zinc selenide immersion gratings for astronomical high-resolution spectroscopy: evaluation of internal attenuation of bulk materials in the short near-infrared region

Science.gov (United States)

Ikeda, Yuji; Kobayashi, Naoto; Kondo, Sohei; Yasui, Chikako; Kuzmenko, Paul J.; Tokoro, Hitoshi; Terada, Hiroshi

2009-08-01

We measure the internal attenuation of bulk crystals of chemical vapor deposition zinc selenide (CVD-ZnS), chemical vapor deposition zinc sulfide (CVD-ZnSe), Si, and GaAs in the short near-infrared (sNIR) region to evaluate the possibility of astronomical immersion gratings with those high refractive index materials. We confirm that multispectral grade CVD-ZnS and CVD-ZnSe are best suited for the immersion gratings, with the smallest internal attenuation of αatt=0.01 to 0.03 cm-1 among the major candidates. The measured attenuation is roughly in proportion to λ-2, suggesting it is dominated by bulk scattering due to the polycrystalline grains rather than by absorption. The total transmittance in the immersion grating is estimated to be at least >80%, even for the spectral resolution of R=300,000. Two potential problems, the scattered light by the bulk material and the degradation of the spectral resolution due to the gradient illumination in the diffracted beam, are investigated and found to be negligible for usual astronomical applications. Since the remaining problem, the difficulty of cutting grooves on CVD-ZnS and CVD-ZnSe, has recently been overcome by the nanoprecision fly-cutting technique, ZnS and ZnSe immersion gratings for astronomy can be technically realized.

A contribution to problems of clean transport of bulk materials

Directory of Open Access Journals (Sweden)

Fedora Jaroslav

1996-03-01

Full Text Available The lecture analyses the problem of development of the pipe conveyor with a rubber belt, the facitities of its application in the practice and environmental aspects resulting from its application. The pipe conveyor is a new perspective transport system. It enables ransporting bulk materials (coal, crushed, rock, coke, plant ash, fertilisers, limestones, time in a specific operations (power plants, heating plants.cellulose, salt, sugar, wheat and other materials with a minimum effect on the environment. The transported material is enclosed in the pipeline so that there is no escape of dust, smell or of the transported material itself. The lecture is aimed at: - the short description of the operating principle and design of the pipe conveyor which was developed in the firm Matador Púchov in cooperation with the firm TEDO, - the analysis of experiencie in working some pipe conveyors which were under operation for a certain

Bulk-Fill Resin Composites

DEFF Research Database (Denmark)

Benetti, Ana Raquel; Havndrup-Pedersen, Cæcilie; Honoré, Daniel

2015-01-01

the restorative procedure. The aim of this study, therefore, was to compare the depth of cure, polymerization contraction, and gap formation in bulk-fill resin composites with those of a conventional resin composite. To achieve this, the depth of cure was assessed in accordance with the International Organization...... for Standardization 4049 standard, and the polymerization contraction was determined using the bonded-disc method. The gap formation was measured at the dentin margin of Class II cavities. Five bulk-fill resin composites were investigated: two high-viscosity (Tetric EvoCeram Bulk Fill, SonicFill) and three low......-viscosity (x-tra base, Venus Bulk Fill, SDR) materials. Compared with the conventional resin composite, the high-viscosity bulk-fill materials exhibited only a small increase (but significant for Tetric EvoCeram Bulk Fill) in depth of cure and polymerization contraction, whereas the low-viscosity bulk...

Feasibility study on diagnosis of material damage using bulk wave mixing technique

Energy Technology Data Exchange (ETDEWEB)

Choi, Jeong Seok; Cho, Youn Ho [Pusan National University, Busan (Korea, Republic of)

2016-02-15

Ultrasonic nonlinear evaluation is generally utilized for detection of not only defects but also microdamage such as corrosion and plastic deformation. Nonlinearity is determined by the amplitude ratio of primary wave second harmonic wave, and the results of its comparison are used for evaluation. Owing to the experimental features, the experimental nonlinearity result contains system nonlinearity and material nonlinearity. System nonlinearity is that which is unwanted by the user; hence, it acts as an error and interrupts analysis. In this study, a bulk wave mixing technique is implemented in order to minimize the system nonlinearity and obtain the reliable analysis results. The biggest advantage of this technique is that experimental nonlinearity contains less system nonlinearity than that for the conventional nonlinear ultrasonic technique. Theoretical and experimental verifications are performed in this study. By comparing the results of the bulk wave mixing technique with those of the conventional technique, the strengths, weaknesses, and application validity of the bulk wave mixing technique are determined.

Novel low temperature processing techniques for apatite ceramics and chitosan polymer composite bulk materials and its mechanical properties

Science.gov (United States)

Onoki, Takamasa; Nakahira, Atsushi; Tago, Tomoyuki; Hasegawa, Yoshiyuki; Kuno, Tomoaki

2012-12-01

A co-precipitation method was used for processing chitosan (CHI)/calcium hydrogen phosphate dehydrate (DCPD) hybrid material. CHI solution was mixed into 1.0-M calcium nitrate solution. CHI/DCPD hybrid material was prepared by the above explained addition of CHI and Ca ion source to 1.0-M diammonium hydrogen phosphate solution. It was observed by transmission electron microscopy that CHI and DCPD were mixed within submicron meter scale. CHI/HA bulk materials derived from the CHI/DCPD hybrid materials were obtained by using a hydrothermal hot-pressing (HHP) method. A pressure of 40 MPa was initially applied to the sample. An HHP autoclave was heated up to 150 °C for 2 h. Modified 3-point bending tests were conducted to obtain an easy estimate of the fracture toughness for the CHI/HA bulk materials made with the HHP method. The critical stress intensity factor Kc of the fabricated CHI/HA bulk materials was enhanced from 0.30 to 0.40 MPam1/2 by the hybridization of CHI into DCPD.

High mechanical Q-factor measurements on silicon bulk material

Energy Technology Data Exchange (ETDEWEB)

Schwarz, Christian; Nawrodt, Ronny; Heinert, Daniel; Schroeter, Anja; Neubert, Ralf; Thuerk, Matthias; Vodel, Wolfgang; Seidel, Paul [Institut fuer Festkoerperphysik, Helmholtzweg 5, D-07743 Jena (Germany); Tuennermann, Andreas [Institut fuer Angewandte Physik, Albert-Einstein-Strasse 15, D-07745 Jena (Germany)

2008-07-01

The direct observation of gravitational waves is one of the biggest challenges in science. Current detectors are limited by different kinds of noise. One of the fundamental noise sources is thermal noise arising from the optical components. One of the most promising attempts to reduce the thermal noise contribution in future detectors will be the use of high Q-factor materials at cryogenic temperatures. Silicon seems to be the most interesting material due to its excellent optical and thermal properties. We present high Q-factor measurements on bulk samples of high purity silicon in a temperature range from 5 to 300 K. The sample dimensions vary between 76.2 mm x 12..75 mm. The Q-factor exceeds 4.10{sup 8} at 6 K. The influence of the crystal orientation, doping and the sample preparation on the Q-factor is discussed.

Method of altering the effective bulk density of solid material and the resulting product: hollow polymeric particles

International Nuclear Information System (INIS)

Kool, L.B.; Nolen, R.L.; Solomon, D.E.

1981-01-01

Hollow spherical particles are made by spraying a mixture of powdered solid material with a solution of a film-forming polymer in a solvent therefor into a heated chamber where the solvent evaporates. The powder is thereby captured in the wall of the hollow polymer particles formed. Such particles are used to form a suspension in a fluid material. The hollow particles are of such size and wall thickness, in relation to the bulk density of the powdered solid material, that the bulk density of each hollow spherical particle is commensurate with the density of the fluid material. The particles thereby remain in suspension over a substantial period of time with little or no agitation of the fluid. (author)

A new miniaturized negative-index meta-atom for tri-band applications

Directory of Open Access Journals (Sweden)

Hossain Mohammad Jakir

2017-07-01

Full Text Available In this paper, a miniature negative index meta-atom was designed; simulated, fabricated and measured based on parallel incidence of electromagnetic wave that can maintain a tri-band applications in microwave spectra. Compare to the other multi-band conventional metamaterial, the proposed meta-atom structure allows miniaturization factor and follows better effective medium ratio (EMR. Finite-integration technique (FIT based computer simulation technology (CST electromagnetic simulator was adopted to examine the design of the meta-atom. It exhibits tri-band response in conjunction with backward wave property over a certain frequency band in the microwave regime. Furthermore, the effective medium ratio is considerably improved compared to previously reported metamaterial. Moreover, few parametric analyses were done with the meta-atom. The size, scattering parameters and effective medium parameters of the proposed negative index miniaturized meta-atom is appropriate for tri-band applications.

A two-dimensional uniplanar transmission-line metamaterial with a negative index of refraction

International Nuclear Information System (INIS)

Elek, Francis; Eleftheriades, George V

2005-01-01

A uniplanar transmission-line (TL) network has been loaded with lumped elements (chip or printed), enabling one to achieve a two-dimensional (2D) uniplanar negative-refractive-index (NRI) metamaterial. The metamaterial consists of a 2D array of unit cells, composed of TL sections connected in series and loaded in a specified manner. The unit cell dimensions can be designed to be much smaller than the operating wavelength, enabling one to identify the structure as an effective medium, with a negative index of refraction. This NRI metamaterial supports transverse electric (TE) waves, as opposed to related previous work on NRI-TL media that supported transverse magnetic (TM) waves. The dispersion characteristics are calculated using a simple, fast 2D loaded TL model with periodic (Bloch) boundary conditions. Subsequently the dispersion relation is simplified in the homogeneous limit, thus allowing one to identify effective permittivities and permeabilities, which are shown to be simultaneously negative. Simulations demonstrating the negative refraction of a plane wave on an interface between such a NRI uniplanar metamaterial and a commensurate positive-refractive-index (PRI) metamaterial verify the validity of the proposed concept and theory. A fully printed unit cell is presented at microwave frequencies (∼10 GHz) along with a prescription for synthesizing an isotropic 3D transmission line NRI metamaterial based on this unit cell

Composites of amorphous and nanocrystalline Zr–Cu–Al–Nb bulk materials synthesized by spark plasma sintering

Energy Technology Data Exchange (ETDEWEB)

Drescher, P., E-mail: philipp.drescher@uni-rostock.de [Fluidic Technology and Microfluidics, Faculty of Mechanical Engineering and Marine Technology, University of Rostock, 18059 Rostock (Germany); Witte, K. [Physics of New Materials, Institute of Physics, University of Rostock, 18051 Rostock (Germany); Yang, B. [Polymer Physics, Institute of Physics, University of Rostock, 18051 Rostock (Germany); Steuer, R.; Kessler, O. [Chair of Materials Science, Faculty of Mechanical Engineering and Marine Technology, University of Rostock, 18059 Rostock (Germany); Burkel, E. [Physics of New Materials, Institute of Physics, University of Rostock, 18051 Rostock (Germany); Schick, C. [Polymer Physics, Institute of Physics, University of Rostock, 18051 Rostock (Germany); Seitz, H. [Fluidic Technology and Microfluidics, Faculty of Mechanical Engineering and Marine Technology, University of Rostock, 18059 Rostock (Germany)

2016-05-15

The fabrication of Zr{sub 70}Cu{sub 24}Al{sub 4}Nb{sub 2} bulk metallic glass composite samples by spark plasma sintering (SPS) process has been successfully realized. The unique characteristics of bulk metallic glasses could lead to the possibility of future applications as new structural and functional materials. The densification of an amorphous Zr{sub 70}Cu{sub 24}Al{sub 4}Nb{sub 2} powder was realized in a systematic study changing the sintering temperature in the SPS process leading to stable composites characteristic of amorphous and nanocrystalline structures. X-ray diffractometry (XRD) and differential scanning calorimetry (DSC) analysis, transmission electron microscopy (TEM) as well as hardness tests were applied to determine the structural and mechanical properties of the sintered materials. A stable amorphous bulk metallic glass based on Zr{sub 70}Cu{sub 24}Al{sub 4}Nb{sub 2} with a low fraction of crystallites could be fabricated applying a nominal sintering temperature of 400 °C. Higher sintering temperatures lead to composites with high fractions of nanocrystalline material with porosities below 0.5%.

Procedure and device for the radiometric determination of the quantity, quality and foreign substances in moved bulk materials

International Nuclear Information System (INIS)

Krone, C.; Jentsch, G.; Berger, J.

1987-01-01

This invention has to do with a procedure and device for the simultaneous radiometric determination of quantity, quality and foreign substances in moved bulk materials in particular lignite at one measuring point. The section of the bulk material discharge is transmitted by nuclides for soft and hard gamma radiation in pairs. The pulse rates are registered in pairs by means of detectors and evaluated in real-time operation

Coagulase-negative Staphylococcus species in bulk milk: Prevalence, distribution, and associated subgroup- and species-specific risk factors.

Science.gov (United States)

De Visscher, A; Piepers, S; Haesebrouck, F; Supré, K; De Vliegher, S

2017-01-01

Coagulase-negative staphylococci (CNS) have become the main pathogens causing bovine mastitis in recent years. A huge variation in species distribution among herds has been observed in several studies, emphasizing the need to identify subgroup- and species-specific herd-level factors to improve our understanding of the differences in ecological and epidemiological nature between species. The use of bulk milk samples enables the inclusion of a large(r) number of herds needed to identify herd-level risk factors and increases the likelihood of recovering enough isolates per species needed for conducting subgroup- and, eventually, species-specific analyses at the same time. This study aimed to describe the prevalence and distribution of CNS species in bulk milk samples and to identify associated subgroup- and species-specific herd-level factors. Ninety percent of all bulk milk samples yielded CNS. Staphylococcus equorum was the predominant species, followed by Staphylococcus haemolyticus and Staphylococcus epidermidis. A seasonal effect was observed for several CNS species. Bulk milk samples from herds with a loose-pack or a tiestall housing system were more likely to yield CNS species compared with herds with a freestall barn, except for S. epidermidis, Staphylococcus simulans, and Staphylococcus cohnii. In September, herds in which udders were clipped had lower odds of yielding Staphylococcus chromogenes, S. simulans, and Staphylococcus xylosus, the CNS species assumed to be most relevant for udder health, in their bulk milk than herds in which udder clipping was not practiced. Bulk milk of herds participating in a monthly veterinary udder health-monitoring program was more likely to yield these 3 CNS species. Herds always receiving their milk quality premium or predisinfecting teats before attachment of the milking cluster had lower odds of having S. equorum in their bulk milk. Herds not using a single dry cotton or paper towel for each cow during premilking udder

Photon management with index-near-zero materials

Energy Technology Data Exchange (ETDEWEB)

Wang, Zhu; Yu, Zongfu [Department of Electrical and Computer Engineering, University of Wisconsin Madison, Madison, Wisconsin 53706 (United States); Wang, Ziyu [Department of Foundation, Southeast University, Chengxian College, 210018 Nanjing (China)

2016-08-01

Index-near-zero materials can be used for effective photon management. They help to restrict the angle of acceptance, resulting in greatly enhanced light trapping limit. In addition, these materials also decrease the radiative recombination, leading to enhanced open circuit voltage and energy efficiency in direct bandgap solar cells.

Mechanisms of the anomalous Pockels effect in bulk water

Science.gov (United States)

Yukita, Shunpei; Suzuki, Yuto; Shiokawa, Naoyuki; Kobayashi, Takayoshi; Tokunaga, Eiji

2018-04-01

The "anomalous" Pockels effect is a phenomenon that a light beam passing between two electrodes in an aqueous electrolyte solution is deflected by an AC voltage applied between the electrodes: the deflection angle is proportional to the voltage such that the incident beam alternately changes its direction. This phenomenon, the Pockels effect in bulk water, apparently contradicts what is believed in nonlinear optics, i.e., macroscopic inversion symmetry should be broken for the second-order nonlinear optical effect to occur such as the first-order electro-optic effect, i.e., the Pockels effect. To clarify the underlying mechanism, the dependence of the effect on the electrode material is investigated to find that the Pockels coefficient with Pt electrodes is two orders of magnitude smaller than with indium tin oxide (ITO) electrodes. It is experimentally confirmed that the Pockels effect of interfacial water in the electric double layer (EDL) on these electrodes shows an electrode dependence similar to the effect in bulk water while the effects depend on the frequency of the AC voltage such that the interfacial signal decreases with frequency but the bulk signal increases with frequency up to 221 Hz. These experimental results lead to a conclusion that the beam deflection is caused by the refractive index gradient in the bulk water region, which is formed transiently by the Pockels effect of interfacial water in the EDL when an AC electric field is applied. The refractive index gradient is caused by the diffuse layer spreading into the bulk region to work as a breaking factor of inversion symmetry of bulk water due to its charge-biased ionic distribution. This mechanism does not contradict the principle of nonlinear optics.

Two-dimensional fluid-filled closed-cell cellular solid as an acoustic metamaterial with negative index

Science.gov (United States)

Dorodnitsyn, V.; Van Damme, B.

2016-04-01

A concept for acoustic metamaterials consisting of a cellular medium with fluid-filled cells is fabricated and studied experimentally. In such a system, the fluid and solid structure explicitly interact, and elastic wave propagation is coupled to both phases. Focusing here on shear wave behavior, we confirm previous numerical studies in three steps. We first measure the material deformations pertaining to three qualitatively different shear wave modes in the frequency range below 3.5 kHz. We then measure the group velocity and demonstrate that, within a certain frequency interval, the group and phase velocity have opposite signs. This shows that the system acts as a negative-index metamaterial. Finally, we confirm the presence of band gaps due to the locally resonant behavior of the cell walls. The demonstrated concept of a closed, fluid-filled cellular material as an acoustic metamaterial opens a wide space for applications.

Feasibility of introducing ferromagnetic materials to onboard bulk high-Tc superconductors to enhance the performance of present maglev systems

International Nuclear Information System (INIS)

Deng, Zigang; Wang, Jiasu; Zheng, Jun; Zhang, Ya; Wang, Suyu

2013-01-01

Highlights: ► Ferromagnetic materials guide the flux distribution of the PMG to bulk positions. ► With ferromagnetic materials, guidance performance can be enhanced greatly. ► A new HTS Maglev system with onboard ferromagnetic materials is designed. ► The design can meet large guidance force requirements for practical applications. -- Abstract: Performance improvement is a long-term research task for the promotion of practical application of promising high-temperature superconducting (HTS) magnetic levitation (maglev) vehicle technologies. We studied the feasibility to enhance the performance of present HTS Maglev systems by introducing ferromagnetic materials to onboard bulk superconductors. The principle here is to make use of the high magnetic permeability of ferromagnetic materials to alter the flux distribution of the permanent magnet guideway for the enhancement of magnetic field density at the position of the bulk superconductors. Ferromagnetic iron plates were added to the upper surface of bulk superconductors and their geometric and positioning effects on the maglev performance were investigated experimentally. Results show that the guidance performance (stability) was enhanced greatly for a particular setup when compared to the present maglev system which is helpful in the application where large guidance forces are needed such as maglev tracks with high degrees of curves

Porous composite with negative thermal expansion obtained by photopolymer additive manufacturing

Directory of Open Access Journals (Sweden)

Akihiro Takezawa

2015-07-01

Full Text Available Additive manufacturing (AM could be a novel method of fabricating composite and porous materials having various effective performances based on mechanisms of their internal geometries. Materials fabricated by AM could rapidly be used in industrial application since they could easily be embedded in the target part employing the same AM process used for the bulk material. Furthermore, multi-material AM has greater potential than usual single-material AM in producing materials with effective properties. Negative thermal expansion is a representative effective material property realized by designing a composite made of two materials with different coefficients of thermal expansion. In this study, we developed a porous composite having planar negative thermal expansion by employing multi-material photopolymer AM. After measurement of the physical properties of bulk photopolymers, the internal geometry was designed by topology optimization, which is the most effective structural optimization in terms of both minimizing thermal stress and maximizing stiffness. The designed structure was converted to a three-dimensional stereolithography (STL model, which is a native digital format of AM, and assembled as a test piece. The thermal expansions of the specimens were measured using a laser scanning dilatometer. Negative thermal expansion corresponding to less than −1 × 10−4 K−1 was observed for each test piece of the N = 3 experiment.

Semiconductor-diode-aided dosimetry of the irradiation of pourable bulk material

International Nuclear Information System (INIS)

Gruenewald, T.; Rudolf, M.

1987-01-01

The irradiation of unpackaged pourable bulk material requires the employment of a dosimeter which can be readily transported along with the material. Planar diffused silicon diodes have been found to be suitable for this purpose. To date these have been used solely for the purpose of dose rate measurements; however, it can be shown that the permanent change in reverse recover time at the p-n junction correlates with the absorbed irradiation dose in the range up to 10 kGy. Appropriate selection of the diode and thermal treatment lead to a linear dependence and enable the silicon dosimeter to be reused. (author). 16 refs, 4 figs

Surface, interface and bulk materials characterization using Indus synchrotron sources

International Nuclear Information System (INIS)

Phase, Deodatta M.

2014-01-01

Synchrotron radiation sources, providing intense, polarized and stable beams of ultra violet, soft and hard x-ray photons, are having great impact on physics, chemistry, biology, materials science and other areas research. In particular synchrotron radiation has revolutionized materials characterization techniques by enhancing its capabilities for investigating the structural, electronic and magnetic properties of solids. The availability of synchrotron sources and necessary instrumentation has led to considerable improvements in spectral resolution and intensities. As a result, application scope of different materials characterization techniques has tremendously increased particularly in the analysis of solid surfaces, interfaces and bulk materials. The Indian synchrotron storage ring, Indus-1 and Indus-2 are in operation at RRCAT, Indore. The UGC-DAE CSR with the help of university scientist had designed and developed an angle integrated photoelectron spectroscopy (AlPES) beam line on Indus-1 storage ring of 450 MeV and polarized light beam line for soft x-ray absorption spectroscopy (SXAS) on Indus-2 storage ring of 2.5 GeV. (author)

Profit Malmquist Index and Its Global Form in the Presence of the Negative Data in DEA

Directory of Open Access Journals (Sweden)

Ghasem Tohidi

2014-01-01

Full Text Available This paper first introduces the allocative and profit efficiency in the presence of the negative data and then presents a new circular index to measure the productivity change of decision making units (DMUs for the case that the dataset contains the inputs and/or outputs with the negative values in data envelopment analysis (DEA. The proposed index is decomposed into four components in the two stages. The range directional model (RDM and the proposed efficiencies are used to compute the proposed index and its components. The interpretations of the components are presented. Finally, a numerical example is organized to illustrate the proposed index and its components at three successive periods of time.

Trions in bulk and monolayer materials: Faddeev equations and hyperspherical harmonics.

Science.gov (United States)

Filikhin, I; Kezerashvili, R Ya; Tsiklauri, Sh M; Vlahovic, B

2018-03-23

The negatively T - and positively T + charged trions in bulk and monolayer semiconductors are studied in the effective mass approximation within the framework of a potential model. The binding energies of trions in various semiconductors are calculated by employing the Faddeev equation with the Coulomb potential in 3D configuration space. Results of calculations of the binding energies for T - are consistent with previous computational studies, while the T + is unbound for all considered cases. The binding energies of trions in monolayer semiconductors are calculated using the method of hyperspherical harmonics by employing the Keldysh potential. It is shown that 2D T - and T + trions are bound and the binding energy of the positive trion is always greater than for the negative trion due to the heavier effective mass of holes. Our calculations demonstrate that screening effects play an important role in the formation of bound states of trions in 2D semiconductors.

The theoretical justification for the fractionation of bulk materials during separation

Directory of Open Access Journals (Sweden)

Piven Valery

2017-01-01

Full Text Available In separating lines at different stages of the technological process is carried out fractionation of the bulk material. These different quality streams subsequently processed on the working bodies or machines that are more suited for a specific faction. Fractionation can increase productivity, reduce costs, reduce the amount of material being processed through the working bodies of the passes. Criteria for selection of the working body for fractionation and its place in the production line depends on many factors and insufficiently developed. The aim of this work is to determine the criteria for evaluating the effectiveness of the working body for the fractionation of the raw material on the basis of a possible increase productivity throughout the production line. The curves obtained by calculation, allow us to estimate the total increase in line speed. Obtained dependence can be used for calculations of separation processes of granular mixtures in the production of building materials, food industry, powder metallurgy, pharmaceutical and other.

The choice of nuclear material measurement strategy in bulk-form in material balance area

International Nuclear Information System (INIS)

Smirnov, V.M.; Sergeev, S.A.; Kirsanov, V.S.

1999-01-01

Concepts have been defined such as Shipment batch, Technological batch, and Accounting batch, it has been found that Shipment and Technological batches should be formed through the arrangement of group of measured Accounting batches. The strategy for nuclear material (NM) measurement based on the Accounting batch is shown to give a possibility to use the advantages for the accounting purposes: ensure safeguards of non-diversion of NM at quantitative (numerical) level, which is a higher grade of safeguards compared to the systems of accounting and control now in force of the US and EURATOM; ensure a guaranteed accuracy and reliability (confidence level) when making up NM balance in Material Balance Area (MBA) and at Federal level, which has been realized only in part in the NM control and accounting systems. Strategy of NM measurement for MBAs counting NM in bulk form has been proposed [ru

Method and Apparatus of Measuring Velocity and Sound Attenuation Coefficient in Bulk Materials Based on the Analysis of the Structure of Sound-Insulation Materials on the Basis of Perlite

Science.gov (United States)

Kapranov, B. I.; Mashanov, A. P.

2017-04-01

This paper presents the results of research and describes the apparatus for measuring the acoustic characteristics of bulk materials. Ultrasound, it has passed through a layer of bulk material, is further passes through an air gap. The presence of air gap prevents from measuring tract mechanical contacts, but complicates the measurement technology Studies were conducted on the example of measuring the acoustic characteristics of the widely used perlite-based sound-proofing material.

Mechanical design engineering. NASA/university advanced design program: Lunar Bulk Material Transport Vehicle

Science.gov (United States)

Daugherty, Paul; Griner, Stewart; Hendrix, Alan; Makarov, Chris; Martiny, Stephen; Meyhoefer, Douglas Ralph; Platt, Cody Claxton; Sivak, John; Wheeler, Elizabeth Fitch

1988-01-01

The design of a Lunar Bulk Material Transport Vehicle (LBMTV) is discussed. Goals set in the project include a payload of 50 cubic feet of lunar soil with a lunar of approximately 800 moon-pounds, a speed of 15 mph, and the ability to handle a grade of 20 percent. Thermal control, an articulated steering mechanism, a dump mechanism, a self-righting mechanism, viable power sources, and a probable control panel are analyzed. The thermal control system involves the use of small strip heaters to heat the housing of electronic equipment in the absence of sufficient solar radiation and multi-layer insulation during periods of intense solar radiation. The entire system uses only 10 W and weighs about 60 pounds, or 10 moon-pounds. The steering mechanism is an articulated steering joint at the center of the vehicle. It utilizes two actuators and yields a turning radius of 10.3 feet. The dump mechanism rotates the bulk material container through an angle of 100 degree using one actuator. The self-righting mechanism consists of two four bar linkages, each of which is powered by the same size actuator as the other linkages. The LBMTV is powered by rechargeable batteries. A running time of at least two hours is attained under a worst case analysis. The weight of the batteries is 100 pounds. A control panel consisting of feedback and control instruments is described. The panel includes all critical information necessary to control the vehicle remotely. The LBMTV is capable of handling many types of cargo. It is able to interface with many types of removable bulk material containers. These containers are made to interface with the three-legged walker, SKITTER. The overall vehicle is about 15 feet in length and has a weight of about 1000 pounds, or 170 lunar pounds.

Effect of rare earth substitution in cobalt ferrite bulk materials

International Nuclear Information System (INIS)

Bulai, G.; Diamandescu, L.; Dumitru, I.; Gurlui, S.; Feder, M.; Caltun, O.F.

2015-01-01

The study was focused on the influence of small amounts of rare earth (RE=La, Ce, Sm, Gd, Dy, Ho, Er, Yb) addition on the microstructure, phase content and magnetic properties of cobalt ferrite bulk materials. The X-Ray diffraction measurements confirmed the formation of the spinel structure but also the presence of secondary phases of RE oxides or orthoferrite in small percentages (up to 3%). Density measurements obtained by Archimedes method revealed a ~1 g cm −3 decrease for the RE doped cobalt ferrite samples compared with stoichiometric one. Both the Mössbauer and Fourier Transform Infrared Spectrocopy analysis results confirmed the formation of the spinel phase. The saturation magnetization and coercive field values of the doped samples obtained by Vibrating Sample Magnetometry were close to those of the pure cobalt ferrite. For magnetostrictive property studies the samples were analyzed using the strain gauge method. Higher maximum magnetostriction coefficients were found for the Ho, Ce, Sm and Yb doped cobalt ferrite bulk materials as related to the stoichiometric CoFe 2 O 4 sample. Moreover, improved strain derivative was observed for these samples but at higher magnetic fields due to the low increase of the coercive field values for doped samples. - Highlights: • Substitution by a large number of rare earth elements was investigated. • First reported results on magnetostriction measurements of RE doped cobalt ferrite. • The doped samples presented an increased porosity and a decreased grain size. • Increased magnetostrctive response was observed for several doped samples

Mesoscale structural characterization within bulk materials by high-energy X-ray microdiffraction

DEFF Research Database (Denmark)

Lienert, U.; Poulsen, H.F.; Kvick, Å.

2001-01-01

A novel diffraction technique for the local three-dimensional characterization within polycrystalline bulk materials is presented. The technique uses high-energy synchrotron radiation (40 keV materials. Focusing broadband optics have been developed...... experimental evidence that a longitudinal resolution down to 10 mum can be obtained. Fundamental materials properties such as the strain/stress state, grain-orientation, -size, and -surface topology can be probed and mapped in three dimensions in favorable cases. Imbedded volumes and interfaces become...... accessible. The technique is nondestructive and allows for in situ studies of samples in complicated environments. A dedicated experimental station has been constructed at the ID11 beamline of the European Synchrotron Radiation Facility. On-line two-dimensional detectors and conical slits have been developed...

Module 13: Bulk Packaging Shipments by Highway

International Nuclear Information System (INIS)

Przybylski, J.L.

1994-07-01

The Hazardous Materials Modular Training Program provides participating United States Department of Energy (DOE) sites with a basic, yet comprehensive, hazardous materials transportation training program for use onsite. This program may be used to assist individual program entities to satisfy the general awareness, safety training, and function specific training requirements addressed in Code of Federal Regulation (CFR), Title 49, Part 172, Subpart H -- ''Training.'' Module 13 -- Bulk Packaging Shipments by Highway is a supplement to the Basic Hazardous Materials Workshop. Module 13 -- Bulk Packaging Shipments by Highway focuses on bulk shipments of hazardous materials by highway mode, which have additional or unique requirements beyond those addressed in the ten module core program. Attendance in this course of instruction should be limited to those individuals with work experience in transporting hazardous materials utilizing bulk packagings and who have completed the Basic Hazardous Materials Workshop or an equivalent. Participants will become familiar with the rules and regulations governing the transportation by highway of hazardous materials in bulk packagings and will demonstrate the application of these requirements through work projects and examination

Negative thermal expansion materials: technological key for control of thermal expansion

OpenAIRE

Koshi Takenaka

2012-01-01

Most materials expand upon heating. However, although rare, some materials contract upon heating. Such negative thermal expansion (NTE) materials have enormous industrial merit because they can control the thermal expansion of materials. Recent progress in materials research enables us to obtain materials exhibiting negative coefficients of linear thermal expansion over −30 ppm K−1. Such giant NTE is opening a new phase of control of thermal expansion in composites. Specifically examining pra...

The influence of ALN-Al gradient material gradient index on ballistic performance

International Nuclear Information System (INIS)

Wang Youcong; Liu Qiwen; Li Yao; Shen Qiang

2013-01-01

Ballistic performance of the gradient material is superior to laminated material, and gradient materials have different gradient types. Using ls-dyna to simulate the ballistic performance of ALN-AL gradient target plates which contain three gradient index (b = 1, b = 0.5, b = 2). Through Hopkinson bar numerical simulation to the target plate materials, we obtained the reflection stress wave and transmission stress wave state of gradient material to get the best gradient index. The internal stress state of gradient material is simulated by amplification processing of the target plate model. When the gradient index b is equal to 1, the gradient target plate is best of all.

Nonlinear propagation of electromagnetic waves in negative-refraction-index composite materials.

Science.gov (United States)

Kourakis, I; Shukla, P K

2005-07-01

We investigate the nonlinear propagation of electromagnetic waves in left-handed materials. For this purpose, we consider a set of coupled nonlinear Schrödinger (CNLS) equations, which govern the dynamics of coupled electric and magnetic field envelopes. The CNLS equations are used to obtain a nonlinear dispersion, which depicts the modulational stability profile of the coupled plane-wave solutions in left-handed materials. An exact (in)stability criterion for modulational interactions is derived, and analytical expressions for the instability growth rate are obtained.

Measurement of the refractive index dispersion of As2Se3 bulk glass and thin films prior to and after laser irradiation and annealing using prism coupling in the near- and mid-infrared spectral range

International Nuclear Information System (INIS)

Carlie, N.; Petit, L.; Musgraves, J. D.; Richardson, K.; Anheier, N. C. Jr.; Qiao, H. A.; Bernacki, B.; Phillips, M. C.

2011-01-01

The prism coupling technique has been utilized to measure the refractive index in the near- and mid-IR spectral region of chalcogenide glasses in bulk and thin film form. A commercial system (Metricon model 2010) has been modified with additional laser sources, detectors, and a new GaP prism to allow the measurement of refractive index dispersion over the 1.5-10.6 μm range. The instrumental error was found to be ±0.001 refractive index units across the entire wavelength region examined. Measurements on thermally evaporated AMTIR2 thin films confirmed that (i) the film deposition process provides thin films with reduced index compared to that of the bulk glass used as a target, (ii) annealing of the films increases the refractive index of the film to the level of the bulk glass used as a target to create it, and (iii) it is possible to locally increase the refractive index of the chalcogenide glass using laser exposure at 632.8 nm.

Laser-induced damage thresholds of bulk and coating optical materials at 1030  nm, 500  fs.

Science.gov (United States)

Gallais, Laurent; Commandré, Mireille

2014-02-01

We report on extensive femtosecond laser damage threshold measurements of optical materials in both bulk and thin-film form. This study, which is based on published and new data, involved simple oxide and fluoride films, composite films made from a mixture of two dielectric materials, metallic films, and the surfaces of various bulk materials: oxides, fluorides, semiconductors, and ionic crystals. The samples were tested in comparable conditions at 1030 nm, 375 to 600 fs, under single-pulse irradiation. A large number of different samples prepared by different deposition techniques have been tested, involving classical materials used in the fabrication of optical thin film components (Ag, AlF3, Al2O3, HfO2, MgF2, Nb2O5, Pt, Sc2O3, SiO2, Ta2O5, Y2O3, and ZrO2) and their combination with codeposition processes. Their behaviors are compared with the surfaces of bulk materials (Al2O3, BaF2, CaF2, Ge, KBr, LiF, MgF2, NaCl, Quartz, Si, ZnS, ZnSe, and different silica glasses). Tabulated values of results are presented and discussed.

Bulk and interface quantum states of electrons in multi-layer heterostructures with topological materials

Science.gov (United States)

Nikolic, Aleksandar; Zhang, Kexin; Barnes, C. H. W.

2018-06-01

In this article we describe the bulk and interface quantum states of electrons in multi-layer heterostructures in one dimension, consisting of topological insulators (TIs) and topologically trivial materials. We use and extend an effective four-band continuum Hamiltonian by introducing position dependence to the eight material parameters of the Hamiltonian. We are able to demonstrate complete conduction-valence band mixing in the interface states. We find evidence for topological features of bulk states of multi-layer TI heterostructures, as well as demonstrating both complete and incomplete conduction-valence band inversion at different bulk state energies. We show that the linear k z terms in the low-energy Hamiltonian, arising from overlap of p z orbitals between different atomic layers in the case of chalcogenides, control the amount of tunneling from TIs to trivial insulators. Finally, we show that the same linear k z terms in the low-energy Hamiltonian affect the material’s ability to form the localised interface state, and we demonstrate that due to this effect the spin and probability density localisation in a thin film of Sb2Te3 is incomplete. We show that changing the parameter that controls the magnitude of the overlap of p z orbitals affects the transport characteristics of the topologically conducting states, with incomplete topological state localisation resulting in increased backscattering.

Nanocharacterization of the negative stiffness of ferroelectric materials

Czech Academy of Sciences Publication Activity Database

Skandani, A.A.; Čtvrtlík, Radim; Al-Haik, M.

2014-01-01

Roč. 105, č. 8 (2014), "082906-1"-"082906-5" ISSN 0003-6951 R&D Projects: GA TA ČR TA03010743 Institutional support: RVO:68378271 Keywords : ferroelectric materials * negative stiffness * thermomechanical environments Subject RIV: JJ - Other Materials Impact factor: 3.302, year: 2014

Standard Guide for Unrestricted Disposition of Bulk Materials Containing Residual Amounts of Radioactivity

CERN Document Server

American Society for Testing and Materials. Philadelphia

2009-01-01

1.1 This guide covers the techniques for obtaining approval for release of materials encountered in decontamination and decommissioning (D&D) from restricted use. This would be addressed in the decommissioning plan (E 1281). It applies to materials that do not meet any of the requirements for regulatory control because of radioactivity content. Fig. 1 shows the logic diagram for determining the materials that could be considered for release. Materials that negotiate this logic tree are referred to as “candidate for release based on dose.” 1.2 The objective of this guide is to provide a methodology for distinguishing between material that must be carefully isolated to prevent human contact from that that can be recycled or otherwise disposed of. It applies to material in which the radioactivity is dispersed more or less uniformly throughout the volume of the material (termed residual in bulk form) as opposed to surface contaminated objects. 1.3 Surface contaminated objects are materials externally co...

Bulk and Thin film Properties of Nanoparticle-based Ionic Materials

Science.gov (United States)

Fang, Jason

2008-03-01

Nanoparticle-based ionic materials (NIMS) offer exciting opportunities for research at the forefront of science and engineering. NIMS are hybrid particles comprised of a charged oligomeric corona attached to hard, inorganic nanoparticle cores. Because of their hybrid nature, physical properties --rheological, optical, electrical, thermal - of NIMS can be tailored over an unusually wide range by varying geometric and chemical characteristics of the core and canopy and thermodynamic variables such as temperature and volume fraction. On one end of the spectrum are materials with a high core content, which display properties similar to crystalline solids, stiff waxes, and gels. At the opposite extreme are systems that spontaneously form particle-based fluids characterized by transport properties remarkably similar to simple liquids. In this poster I will present our efforts to synthesize NIMS and discuss their bulk and surface properties. In particular I will discuss our work on preparing smart surfaces using NIMS.

Color of bulk-fill composite resin restorative materials.

Science.gov (United States)

Barutcigil, Çağatay; Barutcigil, Kubilay; Özarslan, Mehmet Mustafa; Dündar, Ayşe; Yilmaz, Burak

2018-03-01

To evaluate the color stability of novel bulk-fill composite resins. Color measurements of a nanohybrid composite resin (Z550) and 3 bulk-fill composite resins (BLK, AFX, XTF; n = 45) were performed before polymerization. After polymerization, color measurements were repeated and specimens were immersed in distilled water or red wine, or coffee. Color change [CIEDE2000 (ΔE 00 )] was calculated after 24 h, 1 and 3 weeks. Data were analyzed with Kruskal-Wallis, Mann-Whitney U and Wilcoxon tests (α = 0.05). Color changes observed after polymerization were significant for all groups. Color changes observed in distilled water for Z550 and AFX were significant. Color changes after stored in red wine and coffee were significant for all groups. Bulk-fill composite resin color change increased over time for all groups in red wine and coffee (P composite resin and bulk-fill composite resins. AFX had the highest color change in distilled water. The color of tested bulk-fill composite resins significantly changed after immersion in beverages and over time. Color change observed with the nanohybrid composite resin after 1 week was stable. Clinicians should keep in mind that tested composite resins may change color when exposed to water and significantly change color immediately after they are polymerized. In addition, the color change continues over time should the patient is a coffee and/or red wine consumer. © 2017 Wiley Periodicals, Inc.

Optical negative refraction by four-wave mixing in thin metallic nanostructures.

Science.gov (United States)

Palomba, Stefano; Zhang, Shuang; Park, Yongshik; Bartal, Guy; Yin, Xiaobo; Zhang, Xiang

2011-10-30

The law of refraction first derived by Snellius and later introduced as the Huygens-Fermat principle, states that the incidence and refracted angles of a light wave at the interface of two different materials are related to the ratio of the refractive indices in each medium. Whereas all natural materials have a positive refractive index and therefore exhibit refraction in the positive direction, artificially engineered negative index metamaterials have been shown capable of bending light waves negatively. Such a negative refractive index is the key to achieving a perfect lens that is capable of imaging well below the diffraction limit. However, negative index metamaterials are typically lossy, narrow band, and require complicated fabrication processes. Recently, an alternative approach to obtain negative refraction from a very thin nonlinear film has been proposed and experimentally demonstrated in the microwave region. However, such approaches use phase conjugation, which makes optical implementations difficult. Here, we report a simple but different scheme to demonstrate experimentally nonlinear negative refraction at optical frequencies using four-wave mixing in nanostructured metal films. The refractive index can be designed at will by simply tuning the wavelengths of the interacting waves, which could have potential impact on many important applications, such as superlens imaging.

Estimation of Bulk modulus and microhardness of tetrahedral semiconductors

International Nuclear Information System (INIS)

Gorai, Sanjay Kumar

2012-01-01

A general empirical formula was found for calculating of bulk modulus (B) and microhardness (H) from electronegativity and principal quantum number of II-VI, III-V semiconductors. Constant C1, appearing the in the expression of bulk modulus and constants C2 and C3, appearing in the expression of microhardness and the exponent M have following values respectively The numerical values of C1,C2, C3 and M are respectively 206.6, 8.234, 1.291, -1.10 for II-VI 72.4, 31.87, 7.592, -0.95 for III-V semiconductors. Both electro-negativity and principal quantum number can effectively reflect on the chemical bonding behaviour of constituent atoms in these semiconductors. The calculated values of bulk modulus and microhardness are in good agreement with the reported values in the literature. Present study helps in designing novel semiconductor materials, and to further explore the mechanical properties of these semiconductors.

Wave propagation inside one-dimensional photonic crystals with single-negative materials

International Nuclear Information System (INIS)

Wang Ligang; Chen Hong; Zhu Shiyao

2006-01-01

The propagation of light waves in one-dimensional photonic crystals (1DPCs) composed of alternating layers of two kinds of single-negative materials is investigated theoretically. The phase velocity is negative when the frequency of the light wave is smaller than the certain critical frequency ω cr , while the Poynting vector is always positive. At normal incidence, such 1DPCs may act as equivalent left-handed materials. At the inclined incidence, the effective wave vectors inside such 1DPCs do refract negatively, while the effective energy flows do not refract negatively. Therefore, at the inclined incidence, the 1DPCs are not equivalent to the left-handed materials

Photothermal Infrared Radiometry in Experimental Studies of the Pyroelectric Properties of Bulk Materials

Science.gov (United States)

Aleksandrov, S. E.; Gavrilov, G. A.; Kapralov, A. A.; Muratikov, K. L.; Sotnikova, G. Yu.

2017-12-01

A simple and efficient method for determining the pyrolelectric coefficients of ferroelectric and pyroelectric bulk materials by taking into account the heat exchange of a sample with the environment is proposed on the basis of the radiometric registration of the variation dynamics of the temperature of the surface when it is exposed to laser radiation in the form of a temporal step.

Feasibility of introducing ferromagnetic materials to onboard bulk high-T{sub c} superconductors to enhance the performance of present maglev systems

Energy Technology Data Exchange (ETDEWEB)

Deng, Zigang, E-mail: zgdeng@gmail.com [Applied Superconductivity Laboratory (ASCLab), Southwest Jiaotong University (SWJTU), Chengdu, Sichuan 610031 (China); State Key Laboratory of Traction Power (TPL), Southwest Jiaotong University (SWJTU), Chengdu, Sichuan 610031 (China); Wang, Jiasu [Applied Superconductivity Laboratory (ASCLab), Southwest Jiaotong University (SWJTU), Chengdu, Sichuan 610031 (China); Zheng, Jun; Zhang, Ya [Applied Superconductivity Laboratory (ASCLab), Southwest Jiaotong University (SWJTU), Chengdu, Sichuan 610031 (China); State Key Laboratory of Traction Power (TPL), Southwest Jiaotong University (SWJTU), Chengdu, Sichuan 610031 (China); Wang, Suyu [Applied Superconductivity Laboratory (ASCLab), Southwest Jiaotong University (SWJTU), Chengdu, Sichuan 610031 (China)

2013-02-14

Highlights: ► Ferromagnetic materials guide the flux distribution of the PMG to bulk positions. ► With ferromagnetic materials, guidance performance can be enhanced greatly. ► A new HTS Maglev system with onboard ferromagnetic materials is designed. ► The design can meet large guidance force requirements for practical applications. -- Abstract: Performance improvement is a long-term research task for the promotion of practical application of promising high-temperature superconducting (HTS) magnetic levitation (maglev) vehicle technologies. We studied the feasibility to enhance the performance of present HTS Maglev systems by introducing ferromagnetic materials to onboard bulk superconductors. The principle here is to make use of the high magnetic permeability of ferromagnetic materials to alter the flux distribution of the permanent magnet guideway for the enhancement of magnetic field density at the position of the bulk superconductors. Ferromagnetic iron plates were added to the upper surface of bulk superconductors and their geometric and positioning effects on the maglev performance were investigated experimentally. Results show that the guidance performance (stability) was enhanced greatly for a particular setup when compared to the present maglev system which is helpful in the application where large guidance forces are needed such as maglev tracks with high degrees of curves.

Handling of bulk solids theory and practice

CERN Document Server

Shamlou, P A

1990-01-01

Handling of Bulk Solids provides a comprehensive discussion of the field of solids flow and handling in the process industries. Presentation of the subject follows classical lines of separate discussions for each topic, so each chapter is self-contained and can be read on its own. Topics discussed include bulk solids flow and handling properties; pressure profiles in bulk solids storage vessels; the design of storage silos for reliable discharge of bulk materials; gravity flow of particulate materials from storage vessels; pneumatic transportation of bulk solids; and the hazards of solid-mater

Pleural fluid cell-free DNA integrity index to identify cytologically negative malignant pleural effusions including mesotheliomas

International Nuclear Information System (INIS)

Sriram, Krishna B; Courtney, Deborah; Yang, Ian A; Bowman, Rayleen V; Fong, Kwun M; Relan, Vandana; Clarke, Belinda E; Duhig, Edwina E; Windsor, Morgan N; Matar, Kevin S; Naidoo, Rishendran; Passmore, Linda; McCaul, Elizabeth

2012-01-01

The diagnosis of malignant pleural effusions (MPE) is often clinically challenging, especially if the cytology is negative for malignancy. DNA integrity index has been reported to be a marker of malignancy. The aim of this study was to evaluate the utility of pleural fluid DNA integrity index in the diagnosis of MPE. We studied 75 pleural fluid and matched serum samples from consecutive subjects. Pleural fluid and serum ALU DNA repeats [115bp, 247bp and 247bp/115bp ratio (DNA integrity index)] were assessed by real-time quantitative PCR. Pleural fluid and serum mesothelin levels were quantified using ELISA. Based on clinico-pathological evaluation, 52 subjects had MPE (including 16 mesotheliomas) and 23 had benign effusions. Pleural fluid DNA integrity index was higher in MPE compared with benign effusions (1.2 vs. 0.8; p<0.001). Cytology had a sensitivity of 55% in diagnosing MPE. If cytology and pleural fluid DNA integrity index were considered together, they exhibited 81% sensitivity and 87% specificity in distinguishing benign and malignant effusions. In cytology-negative pleural effusions (35 MPE and 28 benign effusions), elevated pleural fluid DNA integrity index had an 81% positive predictive value in detecting MPEs. In the detection of mesothelioma, at a specificity of 90%, pleural fluid DNA integrity index had similar sensitivity to pleural fluid and serum mesothelin (75% each respectively). Pleural fluid DNA integrity index is a promising diagnostic biomarker for identification of MPEs, including mesothelioma. This biomarker may be particularly useful in cases of MPE where pleural aspirate cytology is negative, and could guide the decision to undertake more invasive definitive testing. A prospective validation study is being undertaken to validate our findings and test the clinical utility of this biomarker for altering clinical practice

Negative thermal expansion materials: technological key for control of thermal expansion.

Science.gov (United States)

Takenaka, Koshi

2012-02-01

Most materials expand upon heating. However, although rare, some materials contract upon heating. Such negative thermal expansion (NTE) materials have enormous industrial merit because they can control the thermal expansion of materials. Recent progress in materials research enables us to obtain materials exhibiting negative coefficients of linear thermal expansion over -30 ppm K -1 . Such giant NTE is opening a new phase of control of thermal expansion in composites. Specifically examining practical aspects, this review briefly summarizes materials and mechanisms of NTE as well as composites containing NTE materials, based mainly on activities of the last decade.

Negative thermal expansion materials: technological key for control of thermal expansion

Directory of Open Access Journals (Sweden)

Koshi Takenaka

2012-01-01

Full Text Available Most materials expand upon heating. However, although rare, some materials contract upon heating. Such negative thermal expansion (NTE materials have enormous industrial merit because they can control the thermal expansion of materials. Recent progress in materials research enables us to obtain materials exhibiting negative coefficients of linear thermal expansion over −30 ppm K−1. Such giant NTE is opening a new phase of control of thermal expansion in composites. Specifically examining practical aspects, this review briefly summarizes materials and mechanisms of NTE as well as composites containing NTE materials, based mainly on activities of the last decade.

Negative thermal expansion materials: technological key for control of thermal expansion

International Nuclear Information System (INIS)

Takenaka, Koshi

2012-01-01

Most materials expand upon heating. However, although rare, some materials contract upon heating. Such negative thermal expansion (NTE) materials have enormous industrial merit because they can control the thermal expansion of materials. Recent progress in materials research enables us to obtain materials exhibiting negative coefficients of linear thermal expansion over −30 ppm K −1 . Such giant NTE is opening a new phase of control of thermal expansion in composites. Specifically examining practical aspects, this review briefly summarizes materials and mechanisms of NTE as well as composites containing NTE materials, based mainly on activities of the last decade. (topical review)

Reflection from a flat dielectric film with negative refractive index

OpenAIRE

Hillion, Pierre

2007-01-01

We analyse the reflection of a TM electromagnetic field first on a flat dielectric film and second on a Veselago film with negative refractive index, both films being deposited on a metallic substrat acting as a mirror. An incident harmonic plane wave generates inside a conventional dielectric film a refracted propagating wave and an evanescent wave that does not contribute to reflection on the metallic substrat so that part of the information conveyed by the incident field is lost. At the op...

Effect of electrode materials on a negative ion production in a cesium seeded negative ion source

Energy Technology Data Exchange (ETDEWEB)

Shimizu, Takashi; Morishita, Takutoshi; Kashiwagi, Mieko; Hanada, Masaya; Iga, Takashi; Inoue, Takashi; Watanabe, Kazuhiro; Imai, Tsuyoshi [Japan Atomic Energy Research Inst., Naka, Ibaraki (Japan). Naka Fusion Research Establishment; Wada, Motoi [Doshisha Univ., Kyoto (Japan)

2003-03-01

Effects of plasma grid materials on the negative ion production efficiency in a cesium seeded ion source have been experimentally studied. Grid materials of Au, Ag, Cu, Ni, and Mo were examined. A 2.45 GHz microwave ion source was utilized in the experiment to avoid contamination of tungsten from filament cathode. Relations between the negative ion currents and work functions of the grid were measured for these materials. Influence of the contamination by tungsten on the grid was also investigated. If was clarified that the negative ion production efficiency was determined only by the work function of the grid. The efficiency did not depend on the material itself. The lowest work function of 1.42 eV was obtained for Au grid with Cs, and a high H{sup -} production efficiency of 20.7 mA/kW was measured. This efficiency is about 1.3 times larger than that of Cs/Mo and Cs/Cu. Further improvement of the production efficiency was observed by covering the plasma grid with tungsten and cesium simultaneously. Such co-deposition of W and Cs on the plasma grid produced the negative ion production efficiency of 1.7 times higher than that from the tungsten grid simply covered with Cs. (author)

9 CFR 113.10 - Testing of bulk material for export or for further manufacture.

Science.gov (United States)

2010-01-01

... 9 Animals and Animal Products 1 2010-01-01 2010-01-01 false Testing of bulk material for export or for further manufacture. 113.10 Section 113.10 Animals and Animal Products ANIMAL AND PLANT HEALTH... manufacture. When a product is prepared in a licensed establishment for export in large multiple-dose...

Index change of chalcogenide materials from precision glass molding processes

Science.gov (United States)

Deegan, J.; Walsh, K.; Lindberg, G.; Benson, R.; Gibson, D.; Bayya, S.; Sanghera, J.; Stover, E.

2015-05-01

With the increase in demand for infrared optics for thermal applications and the use of glass molding of chalcogenide materials to support these higher volume optical designs, an investigation of changes to the optical properties of these materials is required. Typical precision glass molding requires specific thermal conditions for proper lens molding of any type of optical glass. With these conditions a change (reduction) of optical index occurs after molding of all oxide glass types and it is presumed that a similar behavior will happen with chalcogenide based materials. We will discuss the effects of a typical molding thermal cycle for use with commercially and newly developed chalcogenide materials and show results of index variation from nominally established material data.

A general solution to the material performance index for bending strength design

International Nuclear Information System (INIS)

Burgess, S.C.; Pasini, D.; Smith, D.J.; Alemzadeh, K.

2006-01-01

This paper presents a general solution to the material performance index for the bending strength design of beams. In general, the performance index for strength design is ρ f q /ρ where σ f is the material strength, ρ is the material density and q is a function of the direction of scaling. Previous studies have only solved q for three particular cases: proportional scaling of width and height (q=2/3), constrained height (q=1) and constrained width (q=1/2). This paper presents a general solution to the exponent q for any arbitrary direction of scaling. The index is used to produce performance maps that rank relative material performance for particular design cases. The performance index and the performance maps are applied to a design case study

Tribology of polymeric nanocomposites friction and wear of bulk materials and coatings

CERN Document Server

Friedrich, Klaus

2013-01-01

Tribology of Polymeric Nanocomposites provides a comprehensive description of polymeric nanocomposites, both as bulk materials and as thin surface coatings, and provides rare, focused coverage of their tribological behavior and potential use in tribological applications. Providing engineers and designers with the preparation techniques, friction and wear mechanisms, property information and evaluation methodology needed to select the right polymeric nanocomposites for the job, this unique book also includes valuable real-world examples of polymeric nanocomposites in a

A fast and robust bulk-loading algorithm for indexing very large digital elevation datasets II. Experimental results

Science.gov (United States)

Rodríguez, Félix R.; Barrena, Manuel

2011-07-01

The spatial indexing of eventually all the available topographic information of Earth is a highly valuable tool for different geoscientific application domains. The Shuttle Radar Topography Mission (SRTM) collected and made available to the public one of the world's largest digital elevation models (DEMs). With the aim of providing on easier and faster access to these data by improving their further analysis and processing, we have indexed the SRTM DEM by means of a spatial index based on the kd-tree data structure, called the Q-tree. This paper is the second in a two-part series that includes a thorough performance analysis to validate the bulk-load algorithm efficiency of the Q-tree. We investigate performance measuring elapsed time in different contexts, analyzing disk space usage, testing response time with typical queries, and validating the final index structure balance. In addition, the paper includes performance comparisons with Oracle 11g that helps to understand the real cost of our proposal. Our tests prove that the proposed algorithm outperforms Oracle 11g using around a 9% of the elapsed time, taking six times less storage with more than 96% of page utilization, and getting faster response times to spatial queries issued on 4.5 million points. In addition to this, the behavior of the spatial index has been successfully tested on both an open GIS (VT Builder) and a visualizer tool derived from the previous one.

Negative Refractive Index Metasurfaces for Enhanced Biosensing

Directory of Open Access Journals (Sweden)

Dragan Tanasković

2010-12-01

Full Text Available In this paper we review some metasurfaces with negative values of effective refractive index, as scaffolds for a new generation of surface plasmon polariton-based biological or chemical sensors. The electromagnetic properties of a metasurface may be tuned by its full immersion into analyte, or by the adsorption of a thin layer on it, both of which change its properties as a plasmonic guide. We consider various simple forms of plasmonic crystals suitable for this purpose. We start with the basic case of a freestanding, electromagnetically symmetrical plasmonic slab and analyze different ultrathin, multilayer structures, to finally consider some two-dimensional “wallpaper” geometries like split ring resonator arrays and fishnet structures. A part of the text is dedicated to the possibility of multifunctionalization where a metasurface structure is simultaneously utilized both for sensing and for selectivity enhancement. Finally we give an overview of surface-bound intrinsic electromagnetic noise phenomena that limits the ultimate performance of a metasurfaces sensor.

Simultaneous measurement of thermal conductivity and heat capacity of bulk and thin film materials using frequency-dependent transient thermoreflectance method.

Science.gov (United States)

Liu, Jun; Zhu, Jie; Tian, Miao; Gu, Xiaokun; Schmidt, Aaron; Yang, Ronggui

2013-03-01

The increasing interest in the extraordinary thermal properties of nanostructures has led to the development of various measurement techniques. Transient thermoreflectance method has emerged as a reliable measurement technique for thermal conductivity of thin films. In this method, the determination of thermal conductivity usually relies much on the accuracy of heat capacity input. For new nanoscale materials with unknown or less-understood thermal properties, it is either questionable to assume bulk heat capacity for nanostructures or difficult to obtain the bulk form of those materials for a conventional heat capacity measurement. In this paper, we describe a technique for simultaneous measurement of thermal conductivity κ and volumetric heat capacity C of both bulk and thin film materials using frequency-dependent time-domain thermoreflectance (TDTR) signals. The heat transfer model is analyzed first to find how different combinations of κ and C determine the frequency-dependent TDTR signals. Simultaneous measurement of thermal conductivity and volumetric heat capacity is then demonstrated with bulk Si and thin film SiO2 samples using frequency-dependent TDTR measurement. This method is further testified by measuring both thermal conductivity and volumetric heat capacity of novel hybrid organic-inorganic thin films fabricated using the atomic∕molecular layer deposition. Simultaneous measurement of thermal conductivity and heat capacity can significantly shorten the development∕discovery cycle of novel materials.

Determination Of Work Indexes Of Basic Ceramic Raw Materials

OpenAIRE

İPEK, Halil; UÇBAŞ, Yaşar

2017-01-01

In this study, the grindability of basic ceramic raw materials have been investigated by using Bond grindability test and the results have been compared. Bond grindability test results show that work indexes of raw materials are dependent on their hardnesses.

First-principles investigation of the bulk and low-index surfaces of MoSe_2

International Nuclear Information System (INIS)

Mirhosseini, Hossein; Roma, Guido; Kiss, Janos; Felser, Claudia

2014-01-01

In the framework of density functional theory, the geometry, electronic structure, and magnetic properties of the bulk and low index surfaces of MoSe_2 have been studied. We have carried out calculations with various exchange-correlation functionals to select one which is able to describe the van der Waals (vdW) interactions and gives the best geometry compared with experiments. The inclusion of the vdW forces, however, does not guarantee a reliable description for the geometry of this compound: some vdW functionals strongly overestimate the interlayer distance, similar to GGA functionals. Our investigation shows that the recently introduced optB86bvdW functional yields the best results for MoSe_2. The vdW functionals have less impact on the electronic structure: the differences between the band structures of the experimental atomic structure, calculated by the vdW-DF and PBE functionals are marginal. We have tried the HSE06 hybrid functional as well but the results are not satisfactory: the overestimated interlayer distance leads to a significant overestimation of the band gap. The band structure of the bulk and monolayer is calculated and by the analysis of the bands character the indirect to direct band-gap transition is explained. The surface energy, work function and band structure of the surfaces are calculated as well. The role of the MoSe_2 buffer layer in Cu(In,Ga)Se_2 based solar cells is discussed by considering the work function values. (authors)

Probing near-normally propagating bulk acoustic waves using pseudo-reflection geometry Brillouin spectroscopy

Science.gov (United States)

Parsons, L. C.; Andrews, G. T.

2012-09-01

Pseudo-reflection geometry Brillouin spectroscopy can be used to probe acoustic wave dispersion approximately along the surface normal of a material system while avoiding the difficulties associated with specularly reflected light encountered in an ideal reflection configuration. As an example of its application, we show analytically that it can be used to determine both the refractive index and bulk acoustic mode velocities of optically-isotropic non-metallic materials and confirm the utility of the approach via a series of experiments on fused quartz, gallium phosphide, water, and porous silicon films.

46 CFR 148.04-23 - Unslaked lime in bulk.

Science.gov (United States)

2010-10-01

... 46 Shipping 5 2010-10-01 2010-10-01 false Unslaked lime in bulk. 148.04-23 Section 148.04-23... HAZARDOUS MATERIALS IN BULK Special Additional Requirements for Certain Material § 148.04-23 Unslaked lime in bulk. (a) Unslaked lime in bulk must be transported in unmanned, all steel, double-hulled barges...

Modelling of bulk superconductor magnetization

International Nuclear Information System (INIS)

Ainslie, M D; Fujishiro, H

2015-01-01

This paper presents a topical review of the current state of the art in modelling the magnetization of bulk superconductors, including both (RE)BCO (where RE = rare earth or Y) and MgB 2 materials. Such modelling is a powerful tool to understand the physical mechanisms of their magnetization, to assist in interpretation of experimental results, and to predict the performance of practical bulk superconductor-based devices, which is particularly important as many superconducting applications head towards the commercialization stage of their development in the coming years. In addition to the analytical and numerical techniques currently used by researchers for modelling such materials, the commonly used practical techniques to magnetize bulk superconductors are summarized with a particular focus on pulsed field magnetization (PFM), which is promising as a compact, mobile and relatively inexpensive magnetizing technique. A number of numerical models developed to analyse the issues related to PFM and optimise the technique are described in detail, including understanding the dynamics of the magnetic flux penetration and the influence of material inhomogeneities, thermal properties, pulse duration, magnitude and shape, and the shape of the magnetization coil(s). The effect of externally applied magnetic fields in different configurations on the attenuation of the trapped field is also discussed. A number of novel and hybrid bulk superconductor structures are described, including improved thermal conductivity structures and ferromagnet–superconductor structures, which have been designed to overcome some of the issues related to bulk superconductors and their magnetization and enhance the intrinsic properties of bulk superconductors acting as trapped field magnets. Finally, the use of hollow bulk cylinders/tubes for shielding is analysed. (topical review)

In Situ Formation of Carbon Nanomaterials on Bulk Metallic Materials

Directory of Open Access Journals (Sweden)

J. Y. Xu

2014-01-01

Full Text Available Carbon nanomaterials were synthesized in situ on bulk 316L stainless steel, pure cobalt, and pure nickel by hybrid surface mechanical attrition treatment (SMAT. The microstructures of the treated samples and the resulted carbon nanomaterials were investigated by SEM and TEM characterizations. Different substrates resulted in different morphologies of products. The diameter of carbon nanomaterials is related to the size of the nanograins on the surface layer of substrates. The possible growth mechanism was discussed. Effects of the main parameters of the synthesis, including the carbon source and gas reactant composition, hydrogen, and the reaction temperature, were studied. Using hybrid SMAT is proved to be an effective way to synthesize carbon nanomaterials in situ on surfaces of metallic materials.

A simplified analytical approach to calculation of the electromagnetic behavior of left-handed metamaterials with a graded refractive index profile

Directory of Open Access Journals (Sweden)

Dalarsson N.

2007-01-01

Full Text Available We investigated the spectral properties of a new class of nanostructured artificial composite materials with tailored electromagnetic response, i.e. negative refractive index materials, also known as "left-handed" metamaterials. We analyzed structures incorporating both ordinary positive index media and negative refractive index metamaterials where the interface may be graded to an arbitrary degree. Utilizing a modified version of the Rosen-Morse function, we derived analytical expressions for the field intensity and spectral reflection and transmission through a graded interface between positive and negative index materials. We compared our results to numerical solutions obtained using the transfer matrix technique. .

Simulation of Field Dependence of Critical Current Densities of Bulk High Tc Superconducting Materials regarding Thermally Activated Flux Motion

Science.gov (United States)

Santosh, M.; Naik, S. Pavan Kumar; Koblischka, M. R.

2017-07-01

In the upcoming generation, bulk high temperature superconductors (HTS) will play a crucial and a promising role in numerous industrial applications ranging from Maglev trains to magnetic resonance imaging, etc. Especially, the bulk HTS as permanent magnets are suitable due to the fact that they can trap magnetic fields being several orders of magnitude higher than those of the best hard ferromagnets. The bulk HTS LREBa2Cu3O7-δ (LREBCO or LRE-123, LRE: Y, Gd, etc.,) materials could obtain very powerful compact superconducting super-magnets, which can be operated at the cheaper liquid nitrogen temperature or below due to higher critical temperatures (i.e., ∼90 K). As a result, the new advanced technology can be utilized in a more attractive manner for a variety of technological and medical applications which have the capacity to revolutionize the field. An understanding of the magnetic field dependence of the critical current density (J c(H)) is important to develop better adapted materials. To achieve this goal, a variety of Jc (H) behaviours of bulk LREBCO samples were modelled regarding thermally activated flux motion. In essence, the Jc (H) curves follows a certain criterion where an exponential model is applied. However, to fit the complete Jc (H) curve of the LRE-123 samples an unique model is necessary to explain the behavior at low and high fields. The modelling of the various superconducting materials could be understood in terms of the pinning mechanisms.

Characterisation of bulk solids

Energy Technology Data Exchange (ETDEWEB)

D. McGlinchey [Glasgow Caledonian University, Glasgow (United Kingdom). Centre for Industrial Bulk Solids Handling

2005-07-01

Handling of powders and bulk solids is a critical industrial technology across a broad spectrum of industries, including minerals processing. With contributions from leading authors in their respective fields, this book provides the reader with a sound understanding of the techniques, importance and application of particulate materials characterisation. It covers the fundamental characteristics of individual particles and bulk particulate materials, and includes discussion of a wide range of measurement techniques, and the use of material characteristics in design and industrial practice. Contents: Characterising particle properties; Powder mechanics and rheology; Characterisation for hopper and stockpile design; Fluidization behaviour; Characterisation for pneumatic conveyor design; Explosiblility; 'Designer' particle characteristics; Current industrial practice; and Future trends. 130 ills.

Observation of bulk-ion heating in a tokamak plasma by application of positive and negative current pulses in TRIAM-1

Energy Technology Data Exchange (ETDEWEB)

Toi, K; Hiraki, N; Nakamura, K; Mitarai, O; Kawai, Y; Itoh, S [Kyushu Univ., Fukuoka (Japan). Research Inst. for Applied Mechanics

1980-09-01

A positive of negative current pulse induced by a pulsed toroidal electric field much higher than the Dreicer field increases the bulk-ion temperature of the plasma centre two to three times, without macroscopic plasma destruction. The decay time of the raised ion temperature agrees well with the prediction from neoclassical transport theory. The magnitude of the positive current pulse is limited by violent current disruption, and that of the negative current by a lack of MHD equilibrium which is due to a marked reduction of the total plasma current. The relevant current-driven instabilities in the turbulent heating of a tokamak plasma, skin heating and inward transfer of the energy deposition in the skin layer are briefly discussed.

Feasibility of introducing ferromagnetic materials to onboard bulk high-Tc superconductors to enhance the performance of present maglev systems

Science.gov (United States)

Deng, Zigang; Wang, Jiasu; Zheng, Jun; Zhang, Ya; Wang, Suyu

2013-02-01

Performance improvement is a long-term research task for the promotion of practical application of promising high-temperature superconducting (HTS) magnetic levitation (maglev) vehicle technologies. We studied the feasibility to enhance the performance of present HTS Maglev systems by introducing ferromagnetic materials to onboard bulk superconductors. The principle here is to make use of the high magnetic permeability of ferromagnetic materials to alter the flux distribution of the permanent magnet guideway for the enhancement of magnetic field density at the position of the bulk superconductors. Ferromagnetic iron plates were added to the upper surface of bulk superconductors and their geometric and positioning effects on the maglev performance were investigated experimentally. Results show that the guidance performance (stability) was enhanced greatly for a particular setup when compared to the present maglev system which is helpful in the application where large guidance forces are needed such as maglev tracks with high degrees of curves.

Investigations on Cs-free alternative materials for negative hydrogen ion formation

Energy Technology Data Exchange (ETDEWEB)

Kurutz, Uwe

2017-01-19

Neutral beam injection (NBI) represents a main auxiliary heating and current drive system for thermonuclear fusion devices. For ITER, a total heating power of up to 33 MW will be delivered for up to one hour pulses at particle energies of up to 1 MeV by two NBI systems. The respective ion sources will therefore have to allow for the extraction and acceleration of negative hydrogen ions at a current density of 200 A/m{sup 2} from a low pressure low temperature hydrogen plasma. Also for the succeeding demonstration reactor DEMO the application of NBI is currently discussed. Respective systems will, however, have to fulfil even higher demands, like higher powers (up to 135 MW), longer pulse lengths (2 h or even cw operation), and more restrictive constrains regarding the reliability and stability. Today efficient NBI negative hydrogen ion sources are based mainly on the conversion of positive hydrogen ions and/or hydrogen atoms at a grid surface coated with caesium. Cs is used for reducing the grid's work function which significantly enhances the particle conversion probability. However, the alkali metal is chemically very reactive and easily forms compounds with residual gas impurities. Furthermore, complex redistribution dynamics of the deposited Cs layer is given. This inherently links the application of Cs with a temporal and spatial non-stability of the negative ion yield, which contradicts the required reliability of a DEMO NBI system. Thus, for DEMO, Cs-free alternative materials for negative ion formation are investigated within this work at a flexible laboratory experiment. An ECR discharge is used which provides comparable parameters (pressure, densities, particle fluxes and -energies) to the NBI ion sources. Negative ion formation is measured above different material samples via laser photodetachment together with global plasma parameters using a Langmuir probe and optical emission spectroscopy. The plasma parameters are used for modelling the

Investigations on Cs-free alternative materials for negative hydrogen ion formation

International Nuclear Information System (INIS)

Kurutz, Uwe

2017-01-01

Neutral beam injection (NBI) represents a main auxiliary heating and current drive system for thermonuclear fusion devices. For ITER, a total heating power of up to 33 MW will be delivered for up to one hour pulses at particle energies of up to 1 MeV by two NBI systems. The respective ion sources will therefore have to allow for the extraction and acceleration of negative hydrogen ions at a current density of 200 A/m 2 from a low pressure low temperature hydrogen plasma. Also for the succeeding demonstration reactor DEMO the application of NBI is currently discussed. Respective systems will, however, have to fulfil even higher demands, like higher powers (up to 135 MW), longer pulse lengths (2 h or even cw operation), and more restrictive constrains regarding the reliability and stability. Today efficient NBI negative hydrogen ion sources are based mainly on the conversion of positive hydrogen ions and/or hydrogen atoms at a grid surface coated with caesium. Cs is used for reducing the grid's work function which significantly enhances the particle conversion probability. However, the alkali metal is chemically very reactive and easily forms compounds with residual gas impurities. Furthermore, complex redistribution dynamics of the deposited Cs layer is given. This inherently links the application of Cs with a temporal and spatial non-stability of the negative ion yield, which contradicts the required reliability of a DEMO NBI system. Thus, for DEMO, Cs-free alternative materials for negative ion formation are investigated within this work at a flexible laboratory experiment. An ECR discharge is used which provides comparable parameters (pressure, densities, particle fluxes and -energies) to the NBI ion sources. Negative ion formation is measured above different material samples via laser photodetachment together with global plasma parameters using a Langmuir probe and optical emission spectroscopy. The plasma parameters are used for modelling the inherently

Doping in controlling the type of conductivity in bulk and nanostructured thermoelectric materials

International Nuclear Information System (INIS)

Fuks, D.; Komisarchik, G.; Kaller, M.; Gelbstein, Y.

2016-01-01

Doping of materials for thermoelectric applications is widely used nowadays to control the type of conductivity. We report the results of ab-initio calculations aimed at developing the consistent scheme for determining the role of impurities that may change the type of conductivity in two attractive thermoelectric classes of materials. It is demonstrated that alloying of TiNiSn with Cu makes the material of n-type, and alloying with Fe leads to p-type conductivity. Similar calculations for PbTe with small amount of Na substituting for Pb leads to p-type conductivity, while Cl substituting for Te makes PbTe an n-type material. It is shown also that for nano-grained materials the n-type conductivity should be observed. The effect of impurities segregating to the grain boundaries in nano-structured PbTe is also discussed. - Highlights: • Bulk and nano-grained TE materials were analyzed by DFT. • The electronic effects on both PbTe and TiNiSn were demonstrated. • The role of impurities on the conductivity type was analyzed. • Interfacial states in nano-grained PbTe affect the conductivity type.

Physico-mechanical characteristics of commercially available bulk-fill composites.

Science.gov (United States)

Leprince, Julian G; Palin, William M; Vanacker, Julie; Sabbagh, Joseph; Devaux, Jacques; Leloup, Gaetane

2014-08-01

Bulk-fill composites have emerged, arguably, as a new "class" of resin-based composites, which are claimed to enable restoration in thick layers, up to 4mm. The objective of this work was to compare, under optimal curing conditions, the physico-mechanical properties of most currently available bulk-fill composites to those of two conventional composite materials chosen as references, one highly filled and one flowable "nano-hybrid" composite. Tetric EvoCeram Bulk Fill (Ivoclar-Vivadent), Venus Bulk Fill (Heraeus-Kulzer), SDR (Dentsply), X-tra Fil (VOCO), X-tra Base (VOCO), Sonic Fill (Kerr), Filtek Bulk Fill (3M-Espe), Xenius (GC) were compared to the two reference materials. The materials were light-cured for 40s in a 2mm×2mm×25mm Teflon mould. Degree of conversion was measured by Raman spectroscopy, Elastic modulus and flexural strength were evaluated by three point bending, surface hardness using Vickers microindentation before and after 24h ethanol storage, and filler weight content by thermogravimetric analysis. The ratio of surface hardness before and after ethanol storage was considered as an evaluation of polymer softening. Data were analyzed by one-way ANOVA and post hoc Tukey's test (p=0.05). The mechanical properties of the bulk-fill composites were mostly lower compared with the conventional high viscosity material, and, at best, comparable to the conventional flowable composite. Linear correlations of the mechanical properties investigated were poor with degree of conversion (0.090.8). Softening in ethanol revealed differences in polymer network density between material types. The reduction of time and improvement of convenience associated with bulk-fill materials is a clear advantage of this particular material class. However, a compromise with mechanical properties compared with more conventional commercially-available nano-hybrid materials was demonstrated by the present work. Given the lower mechanical properties of most bulk-fill materials

Processing bulk natural wood into a high-performance structural material

Science.gov (United States)

Song, Jianwei; Chen, Chaoji; Zhu, Shuze; Zhu, Mingwei; Dai, Jiaqi; Ray, Upamanyu; Li, Yiju; Kuang, Yudi; Li, Yongfeng; Quispe, Nelson; Yao, Yonggang; Gong, Amy; Leiste, Ulrich H.; Bruck, Hugh A.; Zhu, J. Y.; Vellore, Azhar; Li, Heng; Minus, Marilyn L.; Jia, Zheng; Martini, Ashlie; Li, Teng; Hu, Liangbing

2018-02-01

Synthetic structural materials with exceptional mechanical performance suffer from either large weight and adverse environmental impact (for example, steels and alloys) or complex manufacturing processes and thus high cost (for example, polymer-based and biomimetic composites). Natural wood is a low-cost and abundant material and has been used for millennia as a structural material for building and furniture construction. However, the mechanical performance of natural wood (its strength and toughness) is unsatisfactory for many advanced engineering structures and applications. Pre-treatment with steam, heat, ammonia or cold rolling followed by densification has led to the enhanced mechanical performance of natural wood. However, the existing methods result in incomplete densification and lack dimensional stability, particularly in response to humid environments, and wood treated in these ways can expand and weaken. Here we report a simple and effective strategy to transform bulk natural wood directly into a high-performance structural material with a more than tenfold increase in strength, toughness and ballistic resistance and with greater dimensional stability. Our two-step process involves the partial removal of lignin and hemicellulose from the natural wood via a boiling process in an aqueous mixture of NaOH and Na2SO3 followed by hot-pressing, leading to the total collapse of cell walls and the complete densification of the natural wood with highly aligned cellulose nanofibres. This strategy is shown to be universally effective for various species of wood. Our processed wood has a specific strength higher than that of most structural metals and alloys, making it a low-cost, high-performance, lightweight alternative.

Frequency-domain Harman technique for rapid characterization of bulk and thin film thermoelectric materials

Science.gov (United States)

Moran, Samuel

Nanostructured thermoelectrics, often in the form of thin films, may potentially improve the generally poor efficiency of bulk thermoelectric power generators and coolers. In order to characterize the efficiency of these new materials it is necessary to measure their thermoelectric figure of merit, ZT. The only direct measurement of ZT is based on the Harman technique and relies on measuring the voltage drop across a sample subjected to a passing continuous current. Application of this technique to thin films is currently carried out as a time-domain measurement of the voltage as the thermal component decays after switching off an applied voltage. This work develops a technique for direct simultaneous measurement of figure of merit and Seebeck coefficient from the harmonic response of a thermoelectric material under alternating current excitation. A thermocouple mounted on the top surface measures voltage across the device as the frequency of the applied voltage is varied. A thermal model allows the sample thermal conductivity to also be determined and shows good agreement with measurements. This technique provides improved signal-to-noise ratio and accuracy compared to time-domain ZT measurements for comparable conditions while simultaneously measuring Seebeck coefficient. The technique is applied to both bulk and thin film thermoelectric samples.

A setup for measuring the Seebeck coefficient and the electrical resistivity of bulk thermoelectric materials

Science.gov (United States)

Fu, Qiang; Xiong, Yucheng; Zhang, Wenhua; Xu, Dongyan

2017-09-01

This paper presents a setup for measuring the Seebeck coefficient and the electrical resistivity of bulk thermoelectric materials. The sample holder was designed to have a compact structure and can be directly mounted in a standard cryostat system for temperature-dependent measurements. For the Seebeck coefficient measurement, a thin bar-shaped sample is mounted bridging two copper bases; and two ceramic heaters are used to generate a temperature gradient along the sample. Two type T thermocouples are used to determine both temperature and voltage differences between two widely separated points on the sample. The thermocouple junction is flattened into a disk and pressed onto the sample surface by using a spring load. The flexible fixation method we adopted not only simplifies the sample mounting process but also prevents thermal contact deterioration due to the mismatch of thermal expansion coefficients between the sample and other parts. With certain modifications, the sample holder can also be used for four-probe electrical resistivity measurements. High temperature measurements are essential for thermoelectric power generation. The experimental system we developed is capable of measuring the Seebeck coefficient and the electrical resistivity of bulk thermoelectric materials in a wide temperature range from 80 to 500 K, which can be further extended to even higher temperatures. Measurements on two standard materials, constantan and nickel, confirmed the accuracy and the reliability of the system.

Colossal negative thermal expansion in reduced layered ruthenate.

Science.gov (United States)

Takenaka, Koshi; Okamoto, Yoshihiko; Shinoda, Tsubasa; Katayama, Naoyuki; Sakai, Yuki

2017-01-10

Large negative thermal expansion (NTE) has been discovered during the last decade in materials of various kinds, particularly materials associated with a magnetic, ferroelectric or charge-transfer phase transition. Such NTE materials have attracted considerable attention for use as thermal-expansion compensators. Here, we report the discovery of giant NTE for reduced layered ruthenate. The total volume change related to NTE reaches 6.7% in dilatometry, a value twice as large as the largest volume change reported to date. We observed a giant negative coefficient of linear thermal expansion α=-115 × 10 -6  K -1 over 200 K interval below 345 K. This dilatometric NTE is too large to be attributable to the crystallographic unit-cell volume variation with temperature. The highly anisotropic thermal expansion of the crystal grains might underlie giant bulk NTE via microstructural effects consuming open spaces in the sintered body on heating.

Double-negative metamaterial research for accelerator applications

International Nuclear Information System (INIS)

Antipov, S.; Spentzouris, L.; Gai, W.; Liu, W.; Power, J.G.

2007-01-01

Material properties are central to the design of particle accelerators. One area of advanced accelerator research is to investigate novel materials and structures and their potential use in extending capabilities of accelerator components. Within the past decade a new type of artificially constructed material having the unique property of simultaneously negative permittivity and permeability has been realized, and is under intense investigation, primarily by the optical physics and microwave engineering communities [C.M. Soukoulis, Science 315 (2007) 47; D.R. Smith, J.B. Pendry, M.C.K. Wiltshire, Science 305 (2004) 788; J.B. Pendry, A.J. Holden, W.J. Stewart, I. Youngs, Phys. Rev. Lett. 76 (1996) 4773]. Although they are typically constructed of arrays of discrete cells, as long as the condition that the wavelength of applied radiation is significantly greater than the cell dimensions is met, the material mimics a continuous medium and can be described with the bulk properties of permittivity, ε, and permeability, μ. When the permittivity and permeability are simultaneously negative in some frequency range, the metamaterial is called double negative (DNM) or left-handed (LHM) and has unusual properties, such as a negative index of refraction. An investigation of these materials in the context of accelerators is being carried out by IIT and the Argonne Wakefield Accelerator Facility [S. Antipov, W. Liu, W. Gai, J. Power, L. Spentzouris, AIP Conf. Proc. 877 (2006); S. Antipov, W. Liu, J. Power, L. Spentzouris, Design, Fabrication, and Testing of Left-Handed Metamaterial, Wakefield Notes at Argonne Wakefield Accelerator, ]. Waveguides loaded with metamaterials are of interest because the DNM can change the dispersion relation of the waveguide significantly. For example, slow backward waves can be produced in a DNM-loaded waveguide without having corrugations. This article begins with a brief introduction of known design principles for realizing a DNM [J.B. Pendry, A

Large area bulk superconductors

Science.gov (United States)

Miller, Dean J.; Field, Michael B.

2002-01-01

A bulk superconductor having a thickness of not less than about 100 microns is carried by a polycrystalline textured substrate having misorientation angles at the surface thereof not greater than about 15.degree.; the bulk superconductor may have a thickness of not less than about 100 microns and a surface area of not less than about 50 cm.sup.2. The textured substrate may have a thickness not less than about 10 microns and misorientation angles at the surface thereof not greater than about 15.degree.. Also disclosed is a process of manufacturing the bulk superconductor and the polycrystalline biaxially textured substrate material.

Perspective and potential of smart optical materials

Science.gov (United States)

Choi, Sang H.; Duzik, Adam J.; Kim, Hyun-Jung; Park, Yeonjoon; Kim, Jaehwan; Ko, Hyun-U.; Kim, Hyun-Chan; Yun, Sungryul; Kyung, Ki-Uk

2017-09-01

The increasing requirements of hyperspectral imaging optics, electro/photo-chromic materials, negative refractive index metamaterial optics, and miniaturized optical components from micro-scale to quantum-scale optics have all contributed to new features and advancements in optics technology. Development of multifunctional capable optics has pushed the boundaries of optics into new fields that require new disciplines and materials to maximize the potential benefits. The purpose of this study is to understand and show the fundamental materials and fabrication technology for field-controlled spectrally active optics (referred to as smart optics) that are essential for future industrial, scientific, military, and space applications, such as membrane optics, filters, windows for sensors and probes, telescopes, spectroscopes, cameras, light valves, light switches, and flat-panel displays. The proposed smart optics are based on the Stark and Zeeman effects in materials tailored with quantum dot arrays and thin films made from readily polarizable materials via ferroelectricity or ferromagnetism. Bound excitonic states of organic crystals are also capable of optical adaptability, tunability, and reconfigurability. To show the benefits of smart optics, this paper reviews spectral characteristics of smart optical materials and device technology. Experiments testing the quantum-confined Stark effect, arising from rare earth element doping effects in semiconductors, and applied electric field effects on spectral and refractive index are discussed. Other bulk and dopant materials were also discovered to have the same aspect of shifts in spectrum and refractive index. Other efforts focus on materials for creating field-controlled spectrally smart active optics on a selected spectral range. Surface plasmon polariton transmission of light through apertures is also discussed, along with potential applications. New breakthroughs in micro scale multiple zone plate optics as a micro

Effect of adding bulking materials over the composting process of municipal solid biowastes

Directory of Open Access Journals (Sweden)

Ricardo Oviedo-Ocaña

2015-12-01

Full Text Available Biowastes (BW, the main raw materials for the composting installations in developing countries, are characterized for containing uncooked food wastes (FW, high moisture content, low porosity, acidic pH, and low C/N ratios which affects the overall composting process (CP. In this study, we evaluated the effect of adding sugarcane bagasse (SCB and star grass (SG (Cynodon plectostachyus (K. Schum. Pilg. as bulking materials (BM over the quality of the substrate, progress of the process, and quality of the obtained product. In this sense, two pilot-scale experiments were performed. The first one contained a substrate formed by 78% BW and 22% SCB (pile A. The second experiment contained a substrate formed by 66% BW and 34% SG (pile B. For each experiment, control treatments (piles A' and B' respectively were performed by using 100% BW without BM. The results showed that in both cases the adding of BM improved substrate quality (pH, moisture, and total organic C content [TOC], speeding up the starting step (2-3 d and reducing the duration of the thermophilic phase of CP (3 d. However, the physico-chemical properties of both BM increased cooling and maturation phases duration (between 15 and 20 d. Obtained products quality was improved in terms of higher TOC, cation-exchange capacity, bulk density, and higher water holding capacity. Application of obtained products A and B could improve some soil properties like major nutrient, water retention, and increasing the organic matter.

Local behaviour of negative thermal expansion materials

International Nuclear Information System (INIS)

Fornasini, P.; Dalba, G.; Grisenti, R.; Purans, J.; Vaccari, M.; Rocca, F.; Sanson, A.

2006-01-01

EXAFS can represent a powerful probe of the local behaviour of negative thermal expansion (NTE) materials, thanks to the possibility of measuring the expansion of selected inter-atomic bonds and the perpendicular relative atomic displacements. The effectiveness of EXAFS for NTE studies is illustrated by a comparison of results recently obtained on germanium, CuCl and the cuprites Cu 2 O and Ag 2 O

High reliability solid refractive index matching materials for field installable connections in FTTH network

Science.gov (United States)

Saito, Kotaro; Kihara, Mitsuru; Shimizu, Tomoya; Yoneda, Keisuke; Kurashima, Toshio

2015-06-01

We performed environmental and accelerated aging tests to ensure the long-term reliability of solid type refractive index matching material at a splice point. Stable optical characteristics were confirmed in environmental tests based on an IEC standard. In an accelerated aging test at 140 °C, which is very much higher than the specification test temperature, the index matching material itself and spliced fibers passing through it had steady optical characteristics. Then we performed an accelerated aging test on an index matching material attached to a built-in fiber before splicing it in the worst condition, which is different from the normal use configuration. As a result, we confirmed that the repeated insertion and removal of fiber for splicing resulted in failure. We consider that the repetition of adhesion between index matching material and fibers causes the splice to degrade. With this result, we used the Arrhenius model to estimate a median lifetime of about 68 years in a high temperature environment of 60 °C. Thus solid type index matching material at a splice point is highly reliable over long periods under normal conditions of use.

Mechanical characterization of selected adhesives and bulk materials at liquid nitrogen and room temperatures

International Nuclear Information System (INIS)

Fitzpatrick, C.M.; Stoddart, W.C.T.

1977-01-01

This paper presents the results of a series of mechanical tests on selected adhesives and bulk materials. The materials tested are of general interest to designers of magnets for cryogenic service and include several epoxies, a varnish, a B-stage glass cloth, insulation papers, and commercially available fiber-reinforced composites. These tests were performed at room temperature (293 K) and at liquid nitrogen temperature (77 K). The tests include both simple tension tests and lap shear tests with various adherends. The parameters critical to tensile or bond strength were varied as part of the test program. The procedures used to manufacture and test these specimens and the results of the tests are reported in this paper

Electrochemical Characteristics of Layered Transition Metal Oxide Cathode Materials for Lithium Ion Batteries: Surface, Bulk Behavior, and Thermal Properties.

Science.gov (United States)

Tian, Chixia; Lin, Feng; Doeff, Marca M

2018-01-16

Layered lithium transition metal oxides, in particular, NMCs (LiNi x Co y Mn z O 2 ) represent a family of prominent lithium ion battery cathode materials with the potential to increase energy densities and lifetime, reduce costs, and improve safety for electric vehicles and grid storage. Our work has focused on various strategies to improve performance and to understand the limitations to these strategies, which include altering compositions, utilizing cation substitutions, and charging to higher than usual potentials in cells. Understanding the effects of these strategies on surface and bulk behavior and correlating structure-performance relationships advance our understanding of NMC materials. This also provides information relevant to the efficacy of various approaches toward ensuring reliable operation of these materials in batteries intended for demanding traction and grid storage applications. In this Account, we start by comparing NMCs to the isostructural LiCoO 2 cathode, which is widely used in consumer batteries. Effects of changing the metal content (Ni, Mn, Co) upon structure and performance of NMCs are briefly discussed. Our early work on the effects of partial substitution of Al, Fe, and Ti for Co on the electrochemical and bulk structural properties is then covered. The original aim of this work was to reduce the Co content (and thus the raw materials cost) and to determine the effect of the substitutions on the electrochemical and bulk structural properties. More recently, we have turned to the application of synchrotron and advanced microscopy techniques to understand both bulk and surface characteristics of the NMCs. Via nanoscale-to-macroscale spectroscopy and atomically resolved imaging techniques, we were able to determine that the surfaces of NMC undergo heterogeneous reconstruction from a layered structure to rock salt under a variety of conditions. Interestingly, formation of rock salt also occurs under abuse conditions. The surface

Unlocking the Electrocatalytic Activity of Antimony for CO2 Reduction by Two-Dimensional Engineering of the Bulk Material.

Science.gov (United States)

Li, Fengwang; Xue, Mianqi; Li, Jiezhen; Ma, Xinlei; Chen, Lu; Zhang, Xueji; MacFarlane, Douglas R; Zhang, Jie

2017-11-13

Two-dimensional (2D) materials are known to be useful in catalysis. Engineering 3D bulk materials into the 2D form can enhance the exposure of the active edge sites, which are believed to be the origin of the high catalytic activity. Reported herein is the production of 2D "few-layer" antimony (Sb) nanosheets by cathodic exfoliation. Application of this 2D engineering method turns Sb, an inactive material for CO 2 reduction in its bulk form, into an active 2D electrocatalyst for reduction of CO 2 to formate with high efficiency. The high activity is attributed to the exposure of a large number of catalytically active edge sites. Moreover, this cathodic exfoliation process can be coupled with the anodic exfoliation of graphite in a single-compartment cell for in situ production of a few-layer Sb nanosheets and graphene composite. The observed increased activity of this composite is attributed to the strong electronic interaction between graphene and Sb. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

Femtosecond Laser Processing of Membranes for Sensor Devices on different Bulk Materials

Directory of Open Access Journals (Sweden)

Johann Zehetner

2017-01-01

Full Text Available We demonstrate that diaphragms for sensor applications can be fabricated by laser ablation in a~variety of substrates such as ceramics, glass, sapphire or SiC. However, ablation can cause pinholes in membranes made of SiC, Si and metals. Our experiments indicate that pinhole defects in the ablated membranes are affected by ripple structures related to the polarization of the laser. From our simulation results on light propagation in Laser-Induced Periodic Surface Structures (LIPSS we find out that they are acting as a slot waveguide in SiC material. The results further show that field intensity is enhanced inside LIPSS and spreads out at surface distortions promoting the formation of pinholes. The membrane corner area is most vulnerable for pinhole formation. Pinholes funnel laser radiation into the bulk material causing structural damage and stress in the membrane. We show that a~polarization flipping technique inhibits the formation of pin holes caused by LIPSS.

Molecular dynamics simulation of self-diffusion processes in titanium in bulk material, on grain junctions and on surface.

Science.gov (United States)

Sushko, Gennady B; Verkhovtsev, Alexey V; Yakubovich, Alexander V; Schramm, Stefan; Solov'yov, Andrey V

2014-08-21

The process of self-diffusion of titanium atoms in a bulk material, on grain junctions and on surface is explored numerically in a broad temperature range by means of classical molecular dynamics simulation. The analysis is carried out for a nanoscale cylindrical sample consisting of three adjacent sectors and various junctions between nanocrystals. The calculated diffusion coefficient varies by several orders of magnitude for different regions of the sample. The calculated values of the bulk diffusion coefficient correspond reasonably well to the experimental data obtained for solid and molten states of titanium. Investigation of diffusion in the nanocrystalline titanium is of a significant importance because of its numerous technological applications. This paper aims to reduce the lack of data on diffusion in titanium and describe the processes occurring in bulk, at different interfaces and on surface of the crystalline titanium.

Ultra low and negative expansion glass–ceramic materials ...

Indian Academy of Sciences (India)

Ultra low and negative expansion glass–ceramic materials have been obtained from pyrophyllite and blast furnace slag. The batch composition was modified with the addition of lithium carbonate, hydrated alumina, boric acid and nucleating agent (titania). The batch was melted at 1400°C followed by casting in the form of ...

Index of Free and Inexpensive Food and Nutrition Information Materials.

Science.gov (United States)

Gordon, Kathleen, Comp.; And Others

This annotated index contains approximately 2,000 free or inexpensive pamphlets or brochures about food and nutrition. The prime criterion for inclusion of materials was that they be easily available and inexpensive; the cut-off cost was set at $3.00. The majority of materials listed were produced in either Canada or the United States. These…

The Assessment of Positivity and Negativity in Social Networks: The Reliability and Validity of the Social Relationships Index

Science.gov (United States)

Campo, Rebecca A.; Uchino, Bert N.; Holt-Lunstad, Julianne; Vaughn, Allison; Reblin, Maija; Smith, Timothy W.

2009-01-01

The Social Relationships Index (SRI) was designed to examine positivity and negativity in social relationships. Unique features of this scale include its brevity and the ability to examine relationship positivity and negativity at the level of the specific individual and social network. The SRI's psychometric properties were examined in three…

Lower-energy neutron sources for increasing the sensitivity of nuclear gages for measuring the water content of bulk materials

International Nuclear Information System (INIS)

Bailey, S.M.

1977-01-01

The sensitivity of a gage using a nuclear source for measuring the water content of bulk materials, such as plastic concrete, is increased by use of a lithium or fluorine neutron nuclear source. 3 figures

Effect of bulk-fill base material on fracture strength of root-filled teeth restored with laminate resin composite restorations.

Science.gov (United States)

Taha, N A; Maghaireh, G A; Ghannam, A S; Palamara, J E

2017-08-01

To evaluate the effect of using a bulk-fill flowable base material on fracture strength and fracture patterns of root-filled maxillary premolars with MOD preparations restored with laminate restorations. Fifty extracted maxillary premolars were selected for the study. Standardized MOD cavities with endodontic treatment were prepared for all teeth, except for intact control. The teeth were divided randomly into five groups (n=10); (Group 1) sound teeth, (Group 2) unrestored teeth; (Group 3) MOD cavities with Vitrebond base and resin-based composite (Ceram. X One Universal); (Group 4) MOD cavities with 2mm GIC base (Fuji IX GP) and resin-based composite (Ceram. X One Universal) open laminate, (Group 5) MOD cavities were restored with 4mm of bulk-fill flowable base material (SDR) and resin-based composite (Ceram. X One Universal). All teeth were thermocycled and subjected to a 45° ramped oblique load in a universal testing machine. Fracture load and fracture patterns were recorded. Data were analyzed using one-way ANOVA and Dunnett's T3 test. Restoration in general increased the fracture strength compared to unrestored teeth. The fracture strength of group 5 (bulk-fill) was significantly higher than the fracture strength of the GIC laminate groups and not significantly different from the intact teeth (355±112N, P=0.118). The type of failure was unfavorable for most of the groups, with the majority being mixed failures. The use of a bulk-fill flowable base material significantly increased the fracture strength of extracted root-filled teeth with MOD cavities; however it did not improve fracture patterns to more favorable ones. Investigating restorative techniques that may improve the longevity of root-filled premolar teeth restored with direct resin restorations. Copyright © 2017 Elsevier Ltd. All rights reserved.

A coupled melt-freeze temperature index approach in a one-layer model to predict bulk volumetric liquid water content dynamics in snow

Science.gov (United States)

Avanzi, Francesco; Yamaguchi, Satoru; Hirashima, Hiroyuki; De Michele, Carlo

2016-04-01

Liquid water in snow rules runoff dynamics and wet snow avalanches release. Moreover, it affects snow viscosity and snow albedo. As a result, measuring and modeling liquid water dynamics in snow have important implications for many scientific applications. However, measurements are usually challenging, while modeling is difficult due to an overlap of mechanical, thermal and hydraulic processes. Here, we evaluate the use of a simple one-layer one-dimensional model to predict hourly time-series of bulk volumetric liquid water content in seasonal snow. The model considers both a simple temperature-index approach (melt only) and a coupled melt-freeze temperature-index approach that is able to reconstruct melt-freeze dynamics. Performance of this approach is evaluated at three sites in Japan. These sites (Nagaoka, Shinjo and Sapporo) present multi-year time-series of snow and meteorological data, vertical profiles of snow physical properties and snow melt lysimeters data. These data-sets are an interesting opportunity to test this application in different climatic conditions, as sites span a wide latitudinal range and are subjected to different snow conditions during the season. When melt-freeze dynamics are included in the model, results show that median absolute differences between observations and predictions of bulk volumetric liquid water content are consistently lower than 1 vol%. Moreover, the model is able to predict an observed dry condition of the snowpack in 80% of observed cases at a non-calibration site, where parameters from calibration sites are transferred. Overall, the analysis show that a coupled melt-freeze temperature-index approach may be a valid solution to predict average wetness conditions of a snow cover at local scale.

Acoustic cloaking by a near-zero-index phononic crystal

KAUST Repository

Zheng, Li-Yang

2014-04-21

Zero-refractive-index materials may lead to promising applications in various fields. Here, we design and fabricate a near Zero-Refractive-Index (ZRI) material using a phononic crystal (PC) composed of a square array of densely packed square iron rods in air. The dispersion relation exhibits a nearly flat band across the Brillouin zone at the reduced frequency f  = 0.5443c/a, which is due to Fabry-Perot (FP) resonance. By using a retrieval method, we find that both the effective mass density and the reciprocal of the effective bulk modulus are close to zero at frequencies near the flat band. We also propose an equivalent tube network model to explain the mechanisms of the near ZRI effect. This FP-resonance-induced near ZRI material offers intriguing wave manipulation properties. We demonstrate both numerically and experimentally its ability to shield a scattering obstacle and guide acoustic waves through a bent structure.

Recent ARPES experiments on quasi-1D bulk materials and artificial structures.

Science.gov (United States)

Grioni, M; Pons, S; Frantzeskakis, E

2009-01-14

The spectroscopy of quasi-one-dimensional (1D) systems has been a subject of strong interest since the first experimental observations of unusual line shapes in the early 1990s. Angle-resolved photoemission (ARPES) measurements performed with increasing accuracy have greatly broadened our knowledge of the properties of bulk 1D materials and, more recently, of artificial 1D structures. They have yielded a direct view of 1D bands, of open Fermi surfaces, and of characteristic instabilities. They have also provided unique microscopic evidence for the non-conventional, non-Fermi-liquid, behavior predicted by theory, and for strong and singular interactions. Here we briefly review some of the remarkable experimental results obtained in the last decade.

Time-resolved x-ray diffraction techniques for bulk polycrystalline materials under dynamic loading

Energy Technology Data Exchange (ETDEWEB)

Lambert, P. K.; Hustedt, C. J.; Zhao, M.; Ananiadis, A. G.; Hufnagel, T. C. [Department of Materials Science and Engineering, Johns Hopkins University, Baltimore, Maryland 21218 (United States); Vecchio, K. S. [Department of NanoEngineering, University of California San Diego, La Jolla, California 92093 (United States); Huskins, E. L. [Oak Ridge Institute for Science and Education, Oak Ridge, Tennessee 37830 (United States); US Army Research Laboratory, Aberdeen Proving Ground, Aberdeen, Maryland 21005 (United States); Casem, D. T. [US Army Research Laboratory, Aberdeen Proving Ground, Aberdeen, Maryland 21005 (United States); Gruner, S. M. [Department of Physics, Cornell University, Ithaca, New York 14853 (United States); Cornell High Energy Synchrotron Source (CHESS), Cornell University, Ithaca, New York 14853 (United States); Kavli Institute at Cornell for Nanoscale Science, Cornell University, Ithaca, New York 14853 (United States); Tate, M. W.; Philipp, H. T.; Purohit, P.; Weiss, J. T. [Department of Physics, Cornell University, Ithaca, New York 14853 (United States); Woll, A. R. [Cornell High Energy Synchrotron Source (CHESS), Cornell University, Ithaca, New York 14853 (United States); Kannan, V.; Ramesh, K. T. [Department of Mechanical Engineering, Johns Hopkins University, Baltimore, Maryland 21218 (United States); Kenesei, P.; Okasinski, J. S.; Almer, J. [X-ray Science Division, Argonne National Laboratory, Argonne, Illinois 60439 (United States)

2014-09-15

We have developed two techniques for time-resolved x-ray diffraction from bulk polycrystalline materials during dynamic loading. In the first technique, we synchronize a fast detector with loading of samples at strain rates of ∼10{sup 3}–10{sup 4} s{sup −1} in a compression Kolsky bar (split Hopkinson pressure bar) apparatus to obtain in situ diffraction patterns with exposures as short as 70 ns. This approach employs moderate x-ray energies (10–20 keV) and is well suited to weakly absorbing materials such as magnesium alloys. The second technique is useful for more strongly absorbing materials, and uses high-energy x-rays (86 keV) and a fast shutter synchronized with the Kolsky bar to produce short (∼40 μs) pulses timed with the arrival of the strain pulse at the specimen, recording the diffraction pattern on a large-format amorphous silicon detector. For both techniques we present sample data demonstrating the ability of these techniques to characterize elastic strains and polycrystalline texture as a function of time during high-rate deformation.

Synthesis of Bulk Superconducting Magnesium Diboride

Directory of Open Access Journals (Sweden)

Margie Olbinado

2002-06-01

Full Text Available Bulk polycrystalline superconducting magnesium diboride, MgB2, samples were successfully prepared via a one-step sintering program at 750°C, in pre Argon with a pressure of 1atm. Both electrical resistivity and magnetic susceptibility measurements confirmed the superconductivity of the material at 39K, with a transition width of 5K. The polycrystalline nature, granular morphology, and composition of the sintered bulk material were confirmed using X-ray diffractometry (XRD, scanning electron microscopy (SEM, and energy dispersive X-ray analysis (EDX.

Electron and positron contributions to the displacement per atom profile in bulk multi-walled carbon nanotube material irradiated with gamma rays

International Nuclear Information System (INIS)

Leyva Fabelo, Antonio; Pinnera Hernandez, Ibrahin; Leyva Pernia, Diana

2013-01-01

The electron and positron contributions to the effective atom displacement cross-section in multi-walled carbon nanotube bulk materials exposed to gamma rays were calculated. The physical properties and the displacement threshold energy value reported in literature for this material were taken into account. Then, using the mathematical simulation of photon and particle transport in matter, the electron and positron energy flux distributions within the irradiated object were also calculated. Finally, considering both results, the atom displacement damage profiles inside the analyzed bulk carbon nanotube material were determined. The individual contribution from each type of secondary particles generated by the photon interactions was specified. An increasing behavior of the displacement cross-sections for all the studied particles energy range was observed. The particles minimum kinetic energy values that make probabilistically possible the single and multiple atom displacement processes were determined. The positrons contribution importance to the total number of point defects generated during the interaction of gamma rays with the studied materials was confirmed

The prospects for very high-power electron accelerators for processing bulk materials

International Nuclear Information System (INIS)

Cleland, M.R.; Thompson, C.C.; Malone, H.F.

1977-01-01

The recent growth in the industrial usage of ionizing radiation has been stimulated by the development of reliable, high-power, electron beam generators which operate in the beam power range of 10 to 100 kilowatts. This high output has reduced the costs of radiation processes to about 0.001 dollars per megarad-pound of product material. At this rate electron beam treatment is now less expensive than conventional methods for curing plastic and rubber products and sterilizing medical disposables. Future applications of electron beam radiation to bulk chemicals and waste materials will require even larger generators operating in the power range of 100 to 1000 kilowatts to handle greater material thruputs. Unit processing costs must be further reduced because of the lower intrinsic values of these materials. Fortunately, lower unit costs will follow the development of more powerful equipment because most of the cost factors do not increase in proportion to the output power. This is demonstrated by analyzing the downward trends in radiation processing costs as the machine voltage and the beam current are increased. The Dynamitron accelerator technology is reviewed to show that this could be one method of achieving the projected power levels. Several large-scale radiation processes are discussed to show that applications can be found for electron beam systems operating in the projected range. (author)

Phonons of single quintuple Bi 2 Te 3 and Bi 2 Se 3 films and bulk materials

KAUST Repository

Cheng, Wei; Ren, Shang-Fen

2011-01-01

Phonons of single quintuple films of Bi2Te3 and Bi2Se3 and corresponding bulk materials are calculated in detail by MedeA (a trademark of Materials Design) and Vienna ab initio simulation package (VASP). The calculated results with and without spin-orbit couplings are compared, and the important roles that the spin-orbit coupling plays in these materials are discussed. A symmetry breaking caused by the anharmonic potentials around Bi atoms in the single quintuple films is identified and discussed. The observed Raman intensity features in Bi 2Te3 and Bi2Se3 quintuple films are explained. © 2011 American Physical Society.

Phonons of single quintuple Bi 2 Te 3 and Bi 2 Se 3 films and bulk materials

KAUST Repository

Cheng, Wei

2011-03-10

Phonons of single quintuple films of Bi2Te3 and Bi2Se3 and corresponding bulk materials are calculated in detail by MedeA (a trademark of Materials Design) and Vienna ab initio simulation package (VASP). The calculated results with and without spin-orbit couplings are compared, and the important roles that the spin-orbit coupling plays in these materials are discussed. A symmetry breaking caused by the anharmonic potentials around Bi atoms in the single quintuple films is identified and discussed. The observed Raman intensity features in Bi 2Te3 and Bi2Se3 quintuple films are explained. © 2011 American Physical Society.

Stoichiometry control in quantum dots: a viable analog to impurity doping of bulk materials.

Science.gov (United States)

Luther, Joseph M; Pietryga, Jeffrey M

2013-03-26

A growing body of research indicates that the stoichiometry of compound semiconductor quantum dots (QDs) may offer control over the materials' optoelectronic properties in ways that could be invaluable in electronic devices. Quantum dots have been characterized as having a stoichiometric bulk-like core with a highly reconstructed surface of a more flexible composition, consisting essentially of ligated, weakly bound ions. As such, many efforts toward stoichiometry-based control over material properties have focused on ligand manipulation. In this issue of ACS Nano, Murray and Kagan's groups instead demonstrate control of the conductive properties of QD arrays by altering the stoichiometry via atomic infusion using a thermal evaporation technique. In this work, PbSe and PbS QD films are made to show controlled n- or p-type behavior, which is key to developing optimized QD-based electronics. In this Perspective, we discuss recent developments and the future outlook in using stoichiometry as a tool to further manipulate QD material properties in this context.

Mass production of bulk artificial nacre with excellent mechanical properties.

Science.gov (United States)

Gao, Huai-Ling; Chen, Si-Ming; Mao, Li-Bo; Song, Zhao-Qiang; Yao, Hong-Bin; Cölfen, Helmut; Luo, Xi-Sheng; Zhang, Fu; Pan, Zhao; Meng, Yu-Feng; Ni, Yong; Yu, Shu-Hong

2017-08-18

Various methods have been exploited to replicate nacre features into artificial structural materials with impressive structural and mechanical similarity. However, it is still very challenging to produce nacre-mimetics in three-dimensional bulk form, especially for further scale-up. Herein, we demonstrate that large-sized, three-dimensional bulk artificial nacre with comprehensive mimicry of the hierarchical structures and the toughening mechanisms of natural nacre can be facilely fabricated via a bottom-up assembly process based on laminating pre-fabricated two-dimensional nacre-mimetic films. By optimizing the hierarchical architecture from molecular level to macroscopic level, the mechanical performance of the artificial nacre is superior to that of natural nacre and many engineering materials. This bottom-up strategy has no size restriction or fundamental barrier for further scale-up, and can be easily extended to other material systems, opening an avenue for mass production of high-performance bulk nacre-mimetic structural materials in an efficient and cost-effective way for practical applications.Artificial materials that replicate the mechanical properties of nacre represent important structural materials, but are difficult to produce in bulk. Here, the authors exploit the bottom-up assembly of 2D nacre-mimetic films to fabricate 3D bulk artificial nacre with an optimized architecture and excellent mechanical properties.

In situ neutron scattering study of nanostructured PbTe-PbS bulk thermoelectric material

Energy Technology Data Exchange (ETDEWEB)

Ren, Fei [Temple University; Schmidt, Robert D [ORNL; Case, Eldon D [Michigan State University, East Lansing; An, Ke [ORNL

2016-01-01

Nanostructures play an important role in thermoelectric materials. Their thermal stability, such as phase change and evolution at elevated temperatures, is thus of great interest to the thermoelectric community. In this study, in situ neutron diffraction was used to examine the phase evolution of nanostructured bulk PbTe-PbS materials fabricated using hot pressing and pulsed electrical current sintering (PECS). The PbS second phase was observed in all samples in the as-pressed condition. The temperature dependent lattice parameter and phase composition data show an initial formation of PbS precipitates followed by a redissolution during heating. The redissolution process started around 570 600 K, and completed at approximately 780 K. During cooling, the PECS sample followed a reversible curve while the heating/cooling behavior of the hot pressed sample was irreversible.

Quality indexes for selecting control materials of the nuclear reactors

International Nuclear Information System (INIS)

Martinez-Val, J.M.; Pena, J.; Esteban Naudin, A.

1981-01-01

Quality indexes are established and valued for selecting control materials, The requirements for accomplishing such purposes are explained with detailed analysis: absortion cross section must be as high as possible, adequate reactivity evolution versus depletion, good resistance to radiation, appropiate thermal stability, mechanical resistance and ductility, chemical compatibility with the environment, good heat transfer properties, abundant in the nature and low costs. At present Westinghouse desire to commercialize hafnium as control material shows the exciting task of looking for new materials controlling nuclear reactors. (auth.)

Near surface bulk density estimates of NEAs from radar observations and permittivity measurements of powdered geologic material

Science.gov (United States)

Hickson, Dylan; Boivin, Alexandre; Daly, Michael G.; Ghent, Rebecca; Nolan, Michael C.; Tait, Kimberly; Cunje, Alister; Tsai, Chun An

2018-05-01

The variations in near-surface properties and regolith structure of asteroids are currently not well constrained by remote sensing techniques. Radar is a useful tool for such determinations of Near-Earth Asteroids (NEAs) as the power of the reflected signal from the surface is dependent on the bulk density, ρbd, and dielectric permittivity. In this study, high precision complex permittivity measurements of powdered aluminum oxide and dunite samples are used to characterize the change in the real part of the permittivity with the bulk density of the sample. In this work, we use silica aerogel for the first time to increase the void space in the samples (and decrease the bulk density) without significantly altering the electrical properties. We fit various mixing equations to the experimental results. The Looyenga-Landau-Lifshitz mixing formula has the best fit and the Lichtenecker mixing formula, which is typically used to approximate planetary regolith, does not model the results well. We find that the Looyenga-Landau-Lifshitz formula adequately matches Lunar regolith permittivity measurements, and we incorporate it into an existing model for obtaining asteroid regolith bulk density from radar returns which is then used to estimate the bulk density in the near surface of NEA's (101955) Bennu and (25143) Itokawa. Constraints on the material properties appropriate for either asteroid give average estimates of ρbd = 1.27 ± 0.33g/cm3 for Bennu and ρbd = 1.68 ± 0.53g/cm3 for Itokawa. We conclude that our data suggest that the Looyenga-Landau-Lifshitz mixing model, in tandem with an appropriate radar scattering model, is the best method for estimating bulk densities of regoliths from radar observations of airless bodies.

Development of superconductor bulk for superconductor bearing

Energy Technology Data Exchange (ETDEWEB)

Kim, Chan Joong; Jun, Byung Hyuk; Park, Soon Dong (and others)

2008-08-15

Current carrying capacity is one of the most important issues in the consideration of superconductor bulk materials for engineering applications. There are numerous applications of Y-Ba-Cu-O (YBCO) bulk superconductors e.g. magnetic levitation train, flywheel energy storage system, levitation transportation, lunar telescope, centrifugal device, magnetic shielding materials, bulk magnets etc. Accordingly, to obtain YBCO materials in the form of large, single crystals without weak-link problem is necessary. A top seeded melt growth (TSMG) process was used to fabricate single crystal YBCO bulk superconductors. The seeded and infiltration growth (IG) technique was also very promising method for the synthesis of large, single-grain YBCO bulk superconductors with good superconducting properties. 5 wt.% Ag doped Y211 green compacts were sintered at 900 .deg. C {approx} 1200 .deg.C and then a single crystal YBCO was fabricated by an infiltration method. A refinement and uniform distribution of the Y211 particles in the Y123 matrix were achieved by sintering the Ag-doped samples. This enhancement of the critical current density was ascribable to a fine dispersion of the Y211 particles, a low porosity and the presence of Ag particles. In addition, we have designed and manufactured large YBCO single domain with levitation force of 10-13 kg/cm{sup 2} using TSMG processing technique.

Toxic substances registry system: Index of material safety data sheets

Science.gov (United States)

1993-01-01

The Material Safety Data Sheets (MSDS's) listed in this index reflect product inventories and associated MSDS's which were submitted to the Toxic Substances Registry database maintained by the Base Operations Contractor at the Kennedy Space Center. The purpose of this index is to provide KSC government, contractor, and tenant organizations a means to access information on the hazards associated with these chemicals. The Toxic Substance Registry Service (TSRS) was established to manage information dealing with the storage and use of toxic and otherwise hazardous materials at KSC. As a part of this service, the BOC Environmental Health Services maintains a central repository of MSDS's which were provided to TSRS. The data on the TSRS are obtained from NASA, contractor, and tenant organizations who use or store hazardous materials at KSC. It is the responsibility of these organizations to conduct inventories, obtain MSDS's, distribute Hazard Communication information to their employees, and otherwise implement compliance with appropriate Federal, State, and NASA Hazard Communication and Worker Right-to-Know regulations and policies.

Post-cure depth of cure of bulk fill dental resin-composites.

Science.gov (United States)

Alrahlah, A; Silikas, N; Watts, D C

2014-02-01

To determine the post-cure depth of cure of bulk fill resin composites through using Vickers hardness profiles (VHN). Five bulk fill composite materials were examined: Tetric EvoCeram(®) Bulk Fill, X-tra base, Venus(®) Bulk Fill, Filtek™ Bulk Fill, SonicFill™. Three specimens of each material type were prepared in stainless steel molds which contained a slot of dimensions (15 mm × 4 mm × 2 mm), and a top plate. The molds were irradiated from one end. All specimens were stored at 37°C for 24h, before measurement. The Vickers hardness was measured as a function of depth of material, at 0.3mm intervals. Data were analysed by one-way ANOVA using Tukey post hoc tests (α=0.05). The maximum VHN ranged from 37.8 to 77.4, whilst the VHN at 80% of max.VHN ranged from 30.4 to 61.9. The depth corresponding to 80% of max.VHN, ranged from 4.14 to 5.03 mm. One-way ANOVA showed statistically significant differences between materials for all parameters tested. SonicFill exhibited the highest VHN (pFill the lowest (p≤0.001). SonicFill and Tetric EvoCeram Bulk Fill had the greatest depth of cure (5.03 and 4.47 mm, respectively) and was significant's different from X-tra base, Venus Bulk Fill and Filtek Bulk Fill (p≤0.016). Linear regression confirmed a positive regression between max.VHN and filler loading (r(2)=0.94). Bulk fill resin composites can be cured to an acceptable post-cure depth, according to the manufacturers' claims. SonicFill and Tetric EvoCeram Bulk Fill had the greatest depth of cure among the composites examined. Copyright © 2013 Academy of Dental Materials. Published by Elsevier Ltd. All rights reserved.

Confining light with negative refraction in checkerboard metamaterials and photonic crystals

International Nuclear Information System (INIS)

Ramakrishna, S. Anantha; Guenneau, S.; Enoch, S.; Tayeb, G.; Gralak, B.

2007-01-01

We present here a finite slab of triangular checkerboard of negative refractive index material that exhibits a form of extraordinary transmission. We show that such a checkerboard can be used to confine light and can act as an open resonator. Effectively even a single point of intersection between three triangular wedges of negative refractive index may act as a resonator that confines light in the limit when n tends toward -1. We find that the quality of the confinement improves by adding more triangular wedges around the initial point in a checkerboard fashion. The confinement effect is also demonstrated by using a photonic crystal that shows the negative refraction effect

Bulk-fill resin composites: polymerization contraction, depth of cure, and gap formation.

Science.gov (United States)

Benetti, A R; Havndrup-Pedersen, C; Honoré, D; Pedersen, M K; Pallesen, U

2015-01-01

The bulk-filling of deep, wide dental cavities is faster and easier than traditional incremental restoration. However, the extent of cure at the bottom of the restoration should be carefully examined in combination with the polymerization contraction and gap formation that occur during the restorative procedure. The aim of this study, therefore, was to compare the depth of cure, polymerization contraction, and gap formation in bulk-fill resin composites with those of a conventional resin composite. To achieve this, the depth of cure was assessed in accordance with the International Organization for Standardization 4049 standard, and the polymerization contraction was determined using the bonded-disc method. The gap formation was measured at the dentin margin of Class II cavities. Five bulk-fill resin composites were investigated: two high-viscosity (Tetric EvoCeram Bulk Fill, SonicFill) and three low-viscosity (x-tra base, Venus Bulk Fill, SDR) materials. Compared with the conventional resin composite, the high-viscosity bulk-fill materials exhibited only a small increase (but significant for Tetric EvoCeram Bulk Fill) in depth of cure and polymerization contraction, whereas the low-viscosity bulk-fill materials produced a significantly larger depth of cure and polymerization contraction. Although most of the bulk-fill materials exhibited a gap formation similar to that of the conventional resin composite, two of the low-viscosity bulk-fill resin composites, x-tra base and Venus Bulk Fill, produced larger gaps.

Grindability determination of torrefied biomass materials using the Hybrid Work index

Energy Technology Data Exchange (ETDEWEB)

Van Essendelft, D.T.; Zhou, X.; Kang, B.S.-J.

2012-01-01

The grindability of torrefied biomass materials is a difficult parameter to evaluate due to its inhomogeneous character and non-uniform morphology. However, it is necessary to develop a grinding test that is representative of the wide ranging character of biomass and torrefied biomass materials. Previous research has shown that Resistance to Impact Milling (RIM) can be linearly correlated to thermally driven weight loss in biomass. In particular, the RIM equipment was found to supply the right energy level to physically break down structurally deficient biomass materials while leaving the un-touched material relatively intact [1–3]. However, the RIM procedure was not designed to extract the comminution energy. Alternatively, the Bond Work Index (BWI) procedure was developed to accurately assess the grinding energy of brittle materials [4,5]. However, the milling energy is too low to be effective for biomass comminution. In this research, the BWI procedure was utilized with the ball–mill approach in the RIM test to evaluate torrefied biomass materials. The hybridized procedure has been shown to be both highly correlated to energy consumption and sensitive to degree of torrefaction. The proposed Hybrid Work Index (HWI) is certainly useful for assessing torrefaction in a laboratory environment, but it may also be correlated to grinding energy at industrial scales.

On the role of API in determining porosity, pore structure and bulk modulus of the skeletal material in pharmaceutical tablets formed with MCC as sole excipient.

Science.gov (United States)

Ridgway, Cathy; Bawuah, Prince; Markl, Daniel; Zeitler, J Axel; Ketolainen, Jarkko; Peiponen, Kai-Erik; Gane, Patrick

2017-06-30

The physical properties and mechanical integrity of pharmaceutical tablets are of major importance when loading with active pharmaceutical ingredient(s) (API) in order to ensure ease of processing, control of dosage and stability during transportation and handling prior to patient consumption. The interaction between API and excipient, acting as functional extender and binder, however, is little understood in this context. The API indomethacin is combined in this study with microcrystalline cellulose (MCC) at increasing loading levels. Tablets from the defined API/MCC ratios are made under conditions of controlled porosity and tablet thickness, resulting from different compression conditions, and thus compaction levels. Mercury intrusion porosimetry is used to establish the accessible pore volume, pore size distribution and, adopting the observed region of elastic intrusion-extrusion at high pressure, an elastic bulk modulus of the skeletal material is recorded. Porosity values are compared to previously published values derived from terahertz (THz) refractive index data obtained from exactly the same tablet sample sets. It is shown that the elastic bulk modulus is dependent on API wt% loading under constant tablet preparation conditions delivering equal dimensions and porosity. The findings are considered of novel value in respect to establishing consistency of tablet production and optimisation of physical properties. Copyright © 2017 Elsevier B.V. All rights reserved.

Theoretical investigations of the bulk modulus in the tetra-cubic transition of PbTiO3 material

Directory of Open Access Journals (Sweden)

Renan A. P. Ribeiro

2014-01-01

Full Text Available Resulting from ion displacement in a solid under pressure, piezoelectricity is an electrical polarization that can be observed in perovskite-type electronic ceramics, such as PbTiO3, which present cubic and tetragonal symmetries at different pressures. The transition between these crystalline phases is determined theoretically through the bulk modulus from the relationship between material energy and volume. However, the change in the material molecular structure is responsible for the piezoelectric effect. In this study, density functional theory calculations using the Becke 3-Parameter-Lee-Yang-Parr hybrid functional were employed to investigate the structure and properties associated with the transition state of the tetragonal-cubic phase change in PbTiO3 material.

Comparison of self-written waveguide techniques and bulk index matching for low-loss polymer waveguide interconnects

Science.gov (United States)

Burrell, Derek; Middlebrook, Christopher

2016-03-01

Polymer waveguides (PWGs) are used within photonic interconnects as inexpensive and versatile substitutes for traditional optical fibers. The PWGs are typically aligned to silica-based optical fibers for coupling. An epoxide elastomer is then applied and cured at the interface for index matching and rigid attachment. Self-written waveguides (SWWs) are proposed as an alternative to further reduce connection insertion loss (IL) and alleviate marginal misalignment issues. Elastomer material is deposited after the initial alignment, and SWWs are formed by injecting ultraviolet (UV) light into the fiber or waveguide. The coupled UV light cures a channel between the two differing structures. A suitable cladding layer can be applied after development. Such factors as longitudinal gap distance, UV cure time, input power level, polymer material selection and choice of solvent affect the resulting SWWs. Experimental data are compared between purely index-matched samples and those with SWWs at the fiber-PWG interface. It is shown that writing process. Successfully fabricated SWWs reduce overall processing time and enable an effectively continuous low-loss rigid interconnect.

Bulk fill restoratives: to cap or not to cap--that is the question?

Science.gov (United States)

Tomaszewska, Iwona M; Kearns, Jennifer O; Ilie, Nicoleta; Fleming, Garry J P

2015-03-01

To assess the cuspal deflection and cervical microleakage scores of standardised large mesio-occlusal-distal (MOD) cavities filled with different restoration protocols: (1) conventional resin restoratives, (2) bulk fill flowable base materials 'capped' with a conventional dimethacrylate resin-based composite (RBC) or (3) bulk fill resin restorative materials. Standardised MOD cavities were prepared in sixty-four sound maxillary premolar teeth and randomly allocated to eight groups. Restorations were placed in conjunction with a universal bonding system and resin restorative materials were irradiated with a quartz-tungsten-halogen light-curing-unit. Restoration protocol (eight oblique increments of conventional resin restorative, bulk fill flowable base and two occlusal 'capping' RBC increments (three increments in total) or bulk fill resin restorative (two increments)) was the dependent variable. A twin channel deflection measuring gauge measured the buccal and palatal cuspal deflections. Teeth were thermally fatigued, immersed in a 0.2% basic fuchsin dye for 24h, sectioned and examined for cervical microleakage score. Post hoc Tukey's tests highlighted significant differences in the mean total cuspal deflection values between resin restoratives (p fill flowable base materials with occlusal 'capping' RBC increments (restoration protocol 2) compared with bulk fill resin restoratives (restoration protocol 3). Not all bulk fill flowable materials or bulk fill resin restoratives behave in a similar fashion when used to restore standardised MOD cavities in maxillary premolar teeth and material selection is vital in the absence of clinical data. Poorly performing bulk fill flowable materials or bulk fill restoratives can be identified using the cuspal deflection and cervical microleakage protocol which could save the complications encountered clinically when restoring Class II restorations. Copyright © 2015 Elsevier Ltd. All rights reserved.

Broadband giant-refractive-index material based on mesoscopic space-filling curves

Science.gov (United States)

Chang, Taeyong; Kim, Jong Uk; Kang, Seung Kyu; Kim, Hyowook; Kim, Do Kyung; Lee, Yong-Hee; Shin, Jonghwa

2016-08-01

The refractive index is the fundamental property of all optical materials and dictates Snell's law, propagation speed, wavelength, diffraction, energy density, absorption and emission of light in materials. Experimentally realized broadband refractive indices remain 1,800 resulting from a mesoscopic crystal with a dielectric constant greater than three million. This gigantic enhancement effect originates from the space-filling curve concept from mathematics. The principle is inherently very broad band, the enhancement being nearly constant from zero up to the frequency of interest. This broadband giant-refractive-index medium promises not only enhanced resolution in imaging and raised fundamental absorption limits in solar energy devices, but also compact, power-efficient components for optical communication and increased performance in many other applications.

Use of muonic x rays for nondestructive analysis of bulk samples for low Z constituents

International Nuclear Information System (INIS)

Reidy, J.J.; Hutson, R.L.; Daniel, H.; Springer, K.

1978-01-01

Muonic x rays have been used in quantitative analysis on bulk samples of ''tissue equivalent'' material whose primary constituents are low Z elements (Z less than or equal to 20). The muonic x-ray spectrum resulting from negative muons stopping in ''tissue equivalent'' materials has been obtained. Relative muonic x-ray intensities were determined and correlated with atomic abundances in these materials. A comparison of the results for the various samples is presented. This work establishes the usefulness of this technique for analyses of gross specimens (greater than or equal to few grams) for elements with 6 less than or equal to Z less than or equal to 20 and atomic abundances greater than 0.15 percent

Bulk Nano-structured Materials for Turbomachinery Components, Phase I

Data.gov (United States)

National Aeronautics and Space Administration — This SBIR Phase I effort seeks to exploit some of the tremendous benefits that could be attained from a revolutionary new approach to grain refinement in bulk...

Sadder and less accurate? False memory for negative material in depression.

Science.gov (United States)

Joormann, Jutta; Teachman, Bethany A; Gotlib, Ian H

2009-05-01

Previous research has demonstrated that induced sad mood is associated with increased accuracy of recall in certain memory tasks; the effects of clinical depression, however, are likely to be quite different. The authors used the Deese-Roediger-McDermott paradigm to examine the impact of clinical depression on erroneous recall of neutral and/or emotional stimuli. Specifically, they presented Deese-Roediger-McDermott lists that were highly associated with negative, neutral, or positive lures and compared participants diagnosed with major depressive disorder and nondepressed control participants on the accuracy of their recall of presented material and their false recall of never-presented lures. Compared with control participants, major depressive disorder participants recalled fewer words that had been previously presented but were more likely to falsely recall negative lures; there were no differences between major depressive disorder and control participants in false recall of positive or neutral lures. These findings indicate that depression is associated with false memories of negative material.

Soft network materials with isotropic negative Poisson's ratios over large strains.

Science.gov (United States)

Liu, Jianxing; Zhang, Yihui

2018-01-31

Auxetic materials with negative Poisson's ratios have important applications across a broad range of engineering areas, such as biomedical devices, aerospace engineering and automotive engineering. A variety of design strategies have been developed to achieve artificial auxetic materials with controllable responses in the Poisson's ratio. The development of designs that can offer isotropic negative Poisson's ratios over large strains can open up new opportunities in emerging biomedical applications, which, however, remains a challenge. Here, we introduce deterministic routes to soft architected materials that can be tailored precisely to yield the values of Poisson's ratio in the range from -1 to 1, in an isotropic manner, with a tunable strain range from 0% to ∼90%. The designs rely on a network construction in a periodic lattice topology, which incorporates zigzag microstructures as building blocks to connect lattice nodes. Combined experimental and theoretical studies on broad classes of network topologies illustrate the wide-ranging utility of these concepts. Quantitative mechanics modeling under both infinitesimal and finite deformations allows the development of a rigorous design algorithm that determines the necessary network geometries to yield target Poisson ratios over desired strain ranges. Demonstrative examples in artificial skin with both the negative Poisson's ratio and the nonlinear stress-strain curve precisely matching those of the cat's skin and in unusual cylindrical structures with engineered Poisson effect and shape memory effect suggest potential applications of these network materials.

Using the Clear Communication Index to Improve Materials for a Behavioral Intervention.

Science.gov (United States)

Porter, Kathleen J; Alexander, Ramine; Perzynski, Katelynn M; Kruzliakova, Natalie; Zoellner, Jamie M

2018-02-08

Ensuring that written materials used in behavioral interventions are clear is important to support behavior change. This study used the Clear Communication Index (CCI) to assess the original and revised versions of three types of written participant materials from the SIPsmartER intervention. Materials were revised based on original scoring. Scores for the entire index were significantly higher among revised versions than originals (57% versus 41%, p < 0.001); however, few revised materials (n = 2 of 53) achieved the benchmark of ≥90%. Handouts scored higher than worksheets and slide sets for both versions. The proportion of materials scored as having "a single main message" significantly increased between versions for worksheets (7% to 57%, p = 0.003) and slide sets (33% to 67%, p = 0.004). Across individual items, most significant improvements were in Core, with four-items related to the material having a single main message. Findings demonstrate that SIPsmartER's revised materials improved after CCI-informed edits. They advance the evidence and application of the CCI, suggesting it can be effectively used to support improvement in clarity of different types of written materials used in behavioral interventions. Implications for practical considerations of using the tool and suggestions for modifications for specific types of materials are presented.

Using the Steel Vessel Material-Cost Index to Mitigate Shipbuilder Risk

National Research Council Canada - National Science Library

Keating, Edward G; Murphy, Robert; Schank, John F; Birkler, John

2008-01-01

This paper describes how the US Navy structures fixed-price and fixed-price, incentive-fee shipbuilding contracts and how labor- and material-cost indexes can mitigate shipbuilder risk in either type of contract...

Understanding bulk behavior of particulate materials from particle scale simulations

Science.gov (United States)

Deng, Xiaoliang

Particulate materials play an increasingly significant role in various industries, such as pharmaceutical manufacturing, food, mining, and civil engineering. The objective of this research is to better understand bulk behaviors of particulate materials from particle scale simulations. Packing properties of assembly of particles are investigated first, focusing on the effects of particle size, surface energy, and aspect ratio on the coordination number, porosity, and packing structures. The simulation results show that particle sizes, surface energy, and aspect ratio all influence the porosity of packing to various degrees. The heterogeneous force networks within particle assembly under external compressive loading are investigated as well. The results show that coarse-coarse contacts dominate the strong network and coarse-fine contacts dominate the total network. Next, DEM models are developed to simulate the particle dynamics inside a conical screen mill (comil) and magnetically assisted impaction mixer (MAIM), both are important particle processing devices. For comil, the mean residence time (MRT), spatial distribution of particles, along with the collision dynamics between particles as well as particle and vessel geometries are examined as a function of the various operating parameters such as impeller speed, screen hole size, open area, and feed rate. The simulation results can help better understand dry coating experimental results using comil. For MAIM system, the magnetic force is incorporated into the contact model, allowing to describe the interactions between magnets. The simulation results reveal the connections between homogeneity of mixture and particle scale variables such as size of magnets and surface energy of non-magnets. In particular, at the fixed mass ratio of magnets to non-magnets and surface energy the smaller magnets lead to better homogeneity of mixing, which is in good agreement with previously published experimental results. Last but not

Magnetism tuned by the charge states of defects in bulk C-doped SnO2 materials.

Science.gov (United States)

Lu, Ying-Bo; Ling, Z C; Cong, Wei-Yan; Zhang, Peng

2015-10-21

To analyze the controversial conclusions on the magnetism of C-doped SnO2 (SnO2:C) bulk materials between theoretical calculations and experimental observations, we propose the critical role of the charge states of defects in the geometric structures and magnetism, and carry out a series of first principle calculations. By changing the charge states, we can influence Bader charge distributions and atomic orbital occupancies in bulk SnO2:C systems, which consequently conduct magnetism. In all charged SnO2:C supercells, C-2px/py/pz electron occupancies are significantly changed by the charge self-regulation, and thus they make the C-2p orbitals spin polarized, which contribute to the dominant magnetic moment of the system. When the concentration of C dopant in the SnO2 supercell increases, the charge redistribution assigns extra electrons averagely to each dopant, and thus effectively modulates the magnetism. These findings provide an experimentally viable way for controlling the magnetism in these systems.

Omnidirectional Photonic Band Gap Using Low Refractive Index Contrast Materials and its Application in Optical Waveguides

KAUST Repository

Vidal Faez, Angelo

2012-07-01

Researchers have argued for many years that one of the conditions for omnidirectional reflection in a one-dimensional photonic crystal is a strong refractive index contrast between the two constituent dielectric materials. Using numerical simulations and the theory of Anderson localization of light, in this work we demonstrate that an omnidirectional band gap can indeed be created utilizing low refractive index contrast materials when they are arranged in a disordered manner. Moreover, the size of the omnidirectional band gap becomes a controllable parameter, which now depends on the number of layers and not only on the refractive index contrast of the system, as it is widely accepted. This achievement constitutes a major breakthrough in the field since it allows for the development of cheaper and more efficient technologies. Of particular interest is the case of high index contrast one-dimensional photonic crystal fibers, where the propagation losses are mainly due to increased optical scattering from sidewall roughness at the interfaces of high index contrast materials. By using low index contrast materials these losses can be reduced dramatically, while maintaining the confinement capability of the waveguide. This is just one of many applications that could be proven useful for this discovery.

Self-Assembled Soft Optical Negative Index Materials

Science.gov (United States)

2008-08-05

within the MURI indicated that anodization of aluminum films provides hexagonal nano-hole arrays, which, when backfilled with e.g. silver via...is possible and can be implemented using gold or silver nanowires. The metamaterial we designed uses square or hexagonal arrays of thin (10-20nm...acceleration, and adaptive mesh refinement on the interface [22]. Since nanorings (tori) are objects of interest in metamaterial synthesis, we

A Negative Thermal Expansion Material of ZrMgMo3O12

International Nuclear Information System (INIS)

Song Wen-Bo; Liang Er-Jun; Liu Xian-Sheng; Li Zhi-Yuan; Yuan Bao-He; Wang Jun-Qiao

2013-01-01

A material with the formula ZrMgMo 3 O 12 having negative thermal expansion is presented and characterized. It is shown that ZrMgMo 3 O 12 crystallizes in an orthorhombic symmetry with space group Pnma(62) or Pna2 1 (33) and exhibits negative thermal expansion in a large temperature range (α l = −3.8 × 10 −6 K −1 from 300K to 1000K by x-ray diffraction and α l = −3.73 × 10 −6 K −1 from 295K to 775K by dilatometer). ZrMgMo 3 O 12 remains the orthorhombic structure without phase transition or decomposition at least from 123K to 1200K and is not hygroscopic. These properties make it an excellent material with negative thermal expansion for a variety of applications

Diffusion or bulk flow

DEFF Research Database (Denmark)

Schulz, Alexander

2015-01-01

is currently matter of discussion, called passive symplasmic loading. Based on the limited material available, this review compares the different loading modes and suggests that diffusion is the driving force in apoplasmic loaders, while bulk flow plays an increasing role in plants having a continuous...

Broadband Terahertz Refraction Index Dispersion and Loss of Polymeric Dielectric Substrate and Packaging Materials

Science.gov (United States)

Motaharifar, E.; Pierce, R. G.; Islam, R.; Henderson, R.; Hsu, J. W. P.; Lee, Mark

2018-01-01

In the effort to push the high-frequency performance of electronic circuits and signal interconnects from millimeter waves to beyond 1 THz, a quantitative knowledge of complex refraction index values and dispersion in potential dielectric substrate, encapsulation, waveguide, and packaging materials becomes critical. Here we present very broadband measurements of the real and imaginary index spectra of four polymeric dielectric materials considered for use in high-frequency electronics: benzocyclobutene (BCB), polyethylene naphthalate (PEN), the photoresist SU-8, and polydimethylsiloxane (PDMS). Reflectance and transmittance spectra from 3 to 75 THz were made using a Fourier transform spectrometer on freestanding material samples. These data were quantitatively analyzed, taking into account multiple partial reflections from front and back surfaces and molecular bond resonances, where applicable, to generate real and imaginary parts of the refraction index as a function of frequency. All materials showed signatures of infrared active organic molecular bond resonances between 10 and 50 THz. Low-loss transmission windows as well as anti-window bands of high dispersion and loss can be readily identified and incorporated into high-frequency design models.

It's material strength, not a negative Grueneisen gamma

International Nuclear Information System (INIS)

Sinz, K.H.P.H.; Moss, W.C.

1993-01-01

Hydrocode simulations of CORRTEX data (shock position as a function of time) require a model for the material properties of the medium in which the explosion occurs. Prior to the BULLION underground nuclear test, Furnish performed gun experiments on core samples that were taken from a satellite hole near the working point. We have analyzed some of these data and constructed a constitutive model that is consistent with the gun data. The model consists of a Mie-Grueneisen equation of state that is parameterized using a Hugoniot, a Grueneisen gamma that is only volume dependent, and a pressure dependent strength model. Previous analyses of these particular experiments have ignored material strength, because of its lack of influence on numerical simulations of the CORRTEX data. However, if strength is excluded, negative gammas are required to fit Furnish's data, but these negative gammas give an extremely poor fit to the CORRTEX field data. Our simple model, which includes strength, has a positive volume dependent gamma. The model fits Furnish's laboratory data and the measured experimental CORRTEX data. What is remarkable about the model is that all of the parameters in it can be obtained from the gun data, indicating that laboratory experiments of this type (and perhaps others) on core samples are potentially more useful than believed previously

It's material strength, not a negative Grueneisen gamma

International Nuclear Information System (INIS)

Sinz, K.H.P.H.; Moss, W.C.

1993-02-01

Hydrocode simulations of CORRTEX data (shock position as a function of time) require a model for the material properties of the medium in which the explosion occurs. Prior to the BULLION underground nuclear test, Furnish performed gun experiments on core samples that were taken from a satellite hole near the working point. The authors have analyzed some of these data and constructed a constitutive model that is consistent with the gun data. The model consists of a Mie-Grueneisen equation of state that is parameterized using the Hugoniot, a Grueneisen gamma that is only volume dependent, and a pressure dependent strength model. Previous analyses of these particular experiments have ignored material strength, because of its lack of influence on numerical simulations of the CORRTEX data. However, if strength is excluded, negative gammas are required to fit Furnish's data, but these negative gammas give an extremely poor fit to the CORRTEX field data. The simple model, which includes strength, has a positive volume dependent gamma. The model fits Furnish's laboratory data and the measured experimental CORRTEX data. What is remarkable about the model is that all of the parameters in it can be obtained from the gun data, indicating that laboratory experiments of this type (and perhaps others) on core samples are potentially more useful than believed previously

Negative permeability from random particle composites

Energy Technology Data Exchange (ETDEWEB)

Hussain, Shahid, E-mail: shussain2@qinetiq.com

2017-04-15

Artificial media, such as those composed of periodically-spaced wires for negative permittivity and split ring resonators for negative permeability have been extensively investigated for negative refractive index (NRI) applications (Smith et al., 2004; Pendry et al., 1999) [1,2]. This paper presents an alternative method for producing negative permeability: granular (or particulate) composites incorporating magnetic fillers. Artificial media, such as split-ring resonators, are designed to produce a magnetic resonance feature, which results in negative permeability over a narrow frequency range about the resonance frequency. The position of the feature is dependent upon the size of the inclusion. The material in this case is anisotropic, such that the feature is only observable when the materials are orientated in a specific direction relative to the applied field. A similar resonance can be generated in magnetic granular (particulate) materials: ferromagnetic resonance from the natural spin resonance of particles. Although the theoretical resonance profiles in granular composites shows the permeability dipping to negative values, this is rarely observed experimentally due to resonance damping effects. Results are presented for iron in spherical form and in flake form, dispersed in insulating host matrices. The two particle shapes show different permeability performance, with the magnetic flakes producing a negative contribution. This is attributed to the stronger coupling with the magnetic field resulting from the high aspect ratio of the flakes. The accompanying ferromagnetic resonance is strong enough to overcome the effects of damping and produce negative permeability. The size of random particle composites is not dictated by the wavelength of the applied field, so the materials are potentially much thinner than other, more traditional artificial composites at microwave frequencies. - Highlights: • Negative permeability from random particle composites is

The Effect of Bulk Depth and Irradiation Time on the Surface Hardness and Degree of Cure of Bulk-Fill Composites

Directory of Open Access Journals (Sweden)

Farahat F

2016-09-01

Full Text Available Statement of Problem: For many years, application of the composite restoration with a thickness less than 2 mm for achieving the minimum polymerization contraction and stress has been accepted as a principle. But through the recent development in dental material a group of resin based composites (RBCs called Bulk Fill is introduced whose producers claim the possibility of achieving a good restoration in bulks with depths of 4 or even 5 mm. Objectives: To evaluate the effect of irradiation times and bulk depths on the degree of cure (DC of a bulk fill composite and compare it with the universal type. Materials and Methods: This study was conducted on two groups of dental RBCs including Tetric N Ceram Bulk Fill and Tetric N Ceram Universal. The composite samples were prepared in Teflon moulds with a diameter of 5 mm and height of 2, 4 and 6 mm. Then, half of the samples in each depth were cured from the upper side of the mould for 20s by LED light curing unit. The irradiation time for other specimens was 40s. After 24 hours of storage in distilled water, the microhardness of the top and bottom of the samples was measured using a Future Tech (Japan- Model FM 700 Vickers hardness testing machine. Data were analyzed statistically using the one and multi way ANOVAand Tukey’s test (p = 0.050. Results: The DC of Tetric N Ceram Bulk Fill in defined irradiation time and bulk depth was significantly more than the universal type (p < 0.001. Also, the DC of both composites studied was significantly (p < 0.001 reduced by increasing the bulk depths. Increasing the curing time from 20 to 40 seconds had a marginally significant effect (p ≤ 0.040 on the DC of both bulk fill and universal studied RBC samples. Conclusions: The DC of the investigated bulk fill composite was better than the universal type in all the irradiation times and bulk depths. The studied universal and bulk fill RBCs had an appropriate DC at the 2 and 4 mm bulk depths respectively and

The effects of irradiance and exposure time on the surface roughness of bulk-fill composite resin restorative materials

Science.gov (United States)

Alkhudhairy, Fahad I.

2018-01-01

Objectives: To evaluate the surface roughness of 4 different bulk-fill resin-based composites cured using different irradiance levels. Methods: This in vitro study was performed in February 2017 to August 2017 at the College of Dentistry, King Saud University. Twenty-four specimens were prepared from each of the bulk-fill materials [Tetric N-Ceram (TNC), SonicFill (SF), Smart Dentin Replacement (SDR), and Filtek Bulk-Fill (FB)] using a brass metal mold, resulting in a total of 96 specimens, cured using a Bluephase N light curing unit. Half of the total number of specimens (N=48) were cured using high-power irradiance (1200 mW/cm2) for 20 seconds, while the remaining half (N=48) were cured using low power irradiance (650 mW/cm2) for 40 seconds. After 24 hours, baseline surface roughness of each specimen was analyzed using a profilometer, then polished using Sof-lex abrasive disks, and the surface roughness of all groups was assessed. Results: Post-polished SonicFill cured at high irradiance had the highest mean surface roughness (0.23±0.03), whereas pre-polished Smart Dentin Replacement (0.11±0.01) and SonicFill (0.11±0.02) cured at low irradiance had the lowest mean surface roughness. Conclusion: High curing irradiance (1,200 mW/cm2) had no positive influence on the surface roughness of Filtek Bulk Fill and Tetric N-Ceram bulk-fill RBCs compared with lower curing irradiance (650 mW/cm2). However, the difference of curing irradiance significantly affected the surface roughness in SDR and sonic fill RBCs. PMID:29436570

The Oslo Health Study: A Dietary Index Estimating Frequent Intake of Soft Drinks and Rare Intake of Fruit and Vegetables Is Negatively Associated with Bone Mineral Density

Science.gov (United States)

Høstmark, Arne Torbjørn; Søgaard, Anne Johanne; Alvær, Kari; Meyer, Haakon E.

2011-01-01

Background. Since nutritional factors may affect bone mineral density (BMD), we have investigated whether BMD is associated with an index estimating the intake of soft drinks, fruits, and vegetables. Methods. BMD was measured in distal forearm in a subsample of the population-based Oslo Health Study. 2126 subjects had both valid BMD measurements and answered all the questions required for calculating a Dietary Index = the sum of intake estimates of colas and non-cola beverages divided by the sum of intake estimates of fruits and vegetables. We did linear regression analyses to study whether the Dietary Index and the single food items included in the index were associated with BMD. Results. There was a consistent negative association between the Dietary Index and forearm BMD. Among the single index components, colas and non-cola soft drinks were negatively associated with BMD. The negative association between the Dietary Index and BMD prevailed after adjusting for gender, age, and body mass index, length of education, smoking, alcohol intake, and physical activity. Conclusion. An index reflecting frequent intake of soft drinks and rare intake of fruit and vegetables was inversely related to distal forearm bone mineral density. PMID:21772969

Magnetic levitation systems using a high-Tc superconducting bulk magnet

Energy Technology Data Exchange (ETDEWEB)

Ohsaki, Hiroyuki [Dept. of Electrical Engineering, Univ. of Tokyo (Japan); Kitahara, Hirotaka [Dept. of Electrical Engineering, Univ. of Tokyo (Japan); Masada, Eisuke [Dept. of Electrical Engineering, Univ. of Tokyo (Japan)

1996-12-31

Recent development of high-performance high-Tc bulk superconductors is making their application for electromagnetic force use feasible. We have studied electromagnetic levitation systems using high-Tc bulk superconducting material. In this paper, after an overview of superconducting magnetic levitation systems, with an emphasis on high-Tc bulk superconductor applications, experimental results of a high-Tc bulk EMS levitation and FEM analysis results of magnetic gradient levitation using bulk superconductor are described. Problems to be solved for their application are also discussed. (orig.)

Ferromagnetic bulk glassy alloys

International Nuclear Information System (INIS)

Inoue, Akihisa; Makino, Akihiro; Mizushima, Takao

2000-01-01

This paper deals with the review on the formation, thermal stability and magnetic properties of the Fe-based bulk glassy alloys in as-cast bulk and melt-spun ribbon forms. A large supercooled liquid region over 50 K before crystallization was obtained in Fe-(Al, Ga)-(P, C, B, Si), Fe-(Cr, Mo, Nb)-(Al, Ga)-(P, C, B) and (Fe, Co, Ni)-Zr-M-B (M=Ti, Hf, V, Nb, Ta, Cr, Mo and W) systems and bulk glassy alloys were produced in a thickness range below 2 mm for the Fe-(Al, Ga)-(P, C, B, Si) system and 6 mm for the Fe-Co-(Zr, Nb, Ta)-(Mo, W)-B system by copper-mold casting. The ring-shaped glassy Fe-(Al, Ga)-(P, C, B, Si) alloys exhibit much better soft magnetic properties as compared with the ring-shaped alloy made from the melt-spun ribbon because of the formation of the unique domain structure. The good combination of high glass-forming ability and good soft magnetic properties indicates the possibility of future development as a new bulk glassy magnetic material

Graviton localization and Newton law for a dS4 brane in a 5D bulk

International Nuclear Information System (INIS)

Kehagias, A; Tamvakis, K

2002-01-01

We consider a dS 4 brane embedded in a five-dimensional bulk with a positive, vanishing or negative bulk cosmological constant and derive the localized graviton spectrum that consists of a normalizable zero mode separated by a gap from a continuum of massive states. We estimate the massive sector contribution to the static potential at short distances and find that only in the case of a negative bulk cosmological constant is there a range, determined by the effective four-dimensional and bulk cosmological constants, where the conventional Newton law is valid. (letter to the editor)

46 CFR 153.900 - Certificates and authorization to carry a bulk liquid hazardous material.

Science.gov (United States)

2010-10-01

... ship must have a Subchapter D or I Certificate of Inspection that is endorsed to allow the cargo tank... requirements for the bulk liquid cargo; and (2) The ship— (i) Has a Certificate of Inspection, Certificate of...) CERTAIN BULK DANGEROUS CARGOES SHIPS CARRYING BULK LIQUID, LIQUEFIED GAS, OR COMPRESSED GAS HAZARDOUS...

Molybdate Based Ceramic Negative-Electrode Materials for Solid Oxide Cells

DEFF Research Database (Denmark)

Graves, Christopher R.; Reddy Sudireddy, Bhaskar; Mogensen, Mogens Bjerg

2010-01-01

Novel molybdate materials with varying Mo valence were synthesized as possible negative-electrode materials for solid oxide cells. The phase, stability, microstructure and electrical conductivity were characterized. The electrochemical activity for H2O and CO2 reduction and H2 and CO oxidation...... enhanced the electrocatalytic activity and electronic conductivity. The polarization resistances of the best molybdates were two orders of magnitude lower than that of donor-doped strontium titanates. Many of the molybdate materials were significantly activated by cathodic polarization, and they exhibited...... higher performance for cathodic (electrolysis) polarization than for anodic (fuel cell) polarization, which makes them especially interesting for use in electrolysis electrodes. ©2010 COPYRIGHT ECS - The Electrochemical Society...

Revisiting the Balazs thought experiment in the case of a left-handed material: electromagnetic-pulse-induced displacement of a dispersive, dissipative negative-index slab.

Science.gov (United States)

Chau, Kenneth J; Lezec, Henri J

2012-04-23

We propose a set of postulates to describe the mechanical interaction between a plane-wave electromagnetic pulse and a dispersive, dissipative slab having a refractive index of arbitrary sign. The postulates include the Abraham electromagnetic momentum density, a generalized Lorentz force law, and a model for absorption-driven mass transfer from the pulse to the medium. These opto-mechanical mechanisms are incorporated into a one-dimensional finite-difference time-domain algorithm that solves Maxwell's equations and calculates the instantaneous force densities exerted by the pulse onto the slab, the momentum-per-unit-area of the pulse and slab, and the trajectories of the slab and system center-of-mass. We show that the postulates are consistent with conservation of global energy, momentum, and center-of-mass velocity at all times, even for cases in which the refractive index of the slab is negative or zero. Consistency between the set of postulates and well-established conservation laws reinforces the Abraham momentum density as the one true electromagnetic momentum density and enables, for the first time, identification of the correct form of the electromagnetic mass density distribution and development of an explicit model for mass transfer due to absorption, for the most general case of a ponderable medium that is both dispersive and dissipative. © 2012 Optical Society of America

High Performance Bulk Thermoelectric Materials

Energy Technology Data Exchange (ETDEWEB)

Ren, Zhifeng [Boston College, Chestnut Hill, MA (United States)

2013-03-31

Over 13 plus years, we have carried out research on electron pairing symmetry of superconductors, growth and their field emission property studies on carbon nanotubes and semiconducting nanowires, high performance thermoelectric materials and other interesting materials. As a result of the research, we have published 104 papers, have educated six undergraduate students, twenty graduate students, nine postdocs, nine visitors, and one technician.

A comparative study of bulk-fill composites: degree of conversion, post-gel shrinkage and cytotoxicity

Directory of Open Access Journals (Sweden)

Flávia Gonçalves

2018-03-01

Full Text Available Abstract: Bulk-fill composites are claimed to be restorative materials used in deep preparations and effectively photoactivated in layers up to 4 mm. The aim of the present study was to evaluate the degree of conversion, post-gel volumetric shrinkage, and cytotoxicity of six bulk-fill and two conventional composites. Degree of conversion was determined by FTIR spectroscopy; post-gel volumetric shrinkage was determined using the strain gauge method; and cytotoxicity in human fibroblasts was evaluated indirectly by the MTT assay. Data were subjected to one-way ANOVA/Tukey's test (α = 0.05. All materials, including bulk-fill and conventional composites, were classified as non-toxic, with cell viability higher than 70%. Bulk-fill composites exhibited volumetric shrinkage similar to or lower (1.4 to 0.4% than that of conventional composites (1.7–2.1%. However, only four of the bulk-fill composites were able to sustain a homogeneous conversion at the 4-mm depth. Despite their non-toxicity and shrinkage similar to that of conventional materials, not all commercial bulk-fill materials were able to maintain a conversion as high as 80% of the superficial layer, at the 4-mm depth, indicating some failure in the bulk-fill design of some commercial brands. Therefore, the use of bulk-fill materials in dental practice is advantageous, but special attention should be given to the selection and correct use of the materials.

Sensory memory during physiological aging indexed by mismatch negativity (MMN).

Science.gov (United States)

Ruzzoli, Manuela; Pirulli, Cornelia; Brignani, Debora; Maioli, Claudio; Miniussi, Carlo

2012-03-01

Physiological aging affects early sensory-perceptual processes. The aim of this experiment was to evaluate changes in auditory sensory memory in physiological aging using the Mismatch Negativity (MMN) paradigm as index. The MMN is a marker recorded through the electroencephalogram and is used to evaluate the integrity of the memory system. We adopted a new, faster paradigm to look for differences between 3 groups of subjects of different ages (young, middle age and older adults) as a function of short or long intervals between stimuli. We found that older adults did not show MMN at long interval condition and that the duration of MMN varied according to the participants' age. The current study provides electrophysiological evidence supporting the theory that the encoding of stimuli is preserved during normal aging, whereas the maintenance of sensory memory is impaired. Considering the advantage offered by the MMN paradigm used here, these data might be a useful reference point for the assessment of auditory sensory memory in pathological aging (e.g., in neurodegenerative diseases). Copyright © 2012 Elsevier Inc. All rights reserved.

A pressure-amplifying framework material with negative gas adsorption transitions.

Science.gov (United States)

Krause, Simon; Bon, Volodymyr; Senkovska, Irena; Stoeck, Ulrich; Wallacher, Dirk; Többens, Daniel M; Zander, Stefan; Pillai, Renjith S; Maurin, Guillaume; Coudert, François-Xavier; Kaskel, Stefan

2016-04-21

Adsorption-based phenomena are important in gas separations, such as the treatment of greenhouse-gas and toxic-gas pollutants, and in water-adsorption-based heat pumps for solar cooling systems. The ability to tune the pore size, shape and functionality of crystalline porous coordination polymers--or metal-organic frameworks (MOFs)--has made them attractive materials for such adsorption-based applications. The flexibility and guest-molecule-dependent response of MOFs give rise to unexpected and often desirable adsorption phenomena. Common to all isothermal gas adsorption phenomena, however, is increased gas uptake with increased pressure. Here we report adsorption transitions in the isotherms of a MOF (DUT-49) that exhibits a negative gas adsorption; that is, spontaneous desorption of gas (methane and n-butane) occurs during pressure increase in a defined temperature and pressure range. A combination of in situ powder X-ray diffraction, gas adsorption experiments and simulations shows that this adsorption behaviour is controlled by a sudden hysteretic structural deformation and pore contraction of the MOF, which releases guest molecules. These findings may enable technologies using frameworks capable of negative gas adsorption for pressure amplification in micro- and macroscopic system engineering. Negative gas adsorption extends the series of counterintuitive phenomena such as negative thermal expansion and negative refractive indices and may be interpreted as an adsorptive analogue of force-amplifying negative compressibility transitions proposed for metamaterials.

Synthesis of bulk nanocrystalline Pb-Sn-Te alloy under high pressure

International Nuclear Information System (INIS)

Zhu, P W; Chen, L X; Jia, X; Ma, H A; Ren, G Z; Guo, W L; Liu, H J; Zou, G T

2002-01-01

Pb-Sn-Te bulk nanocrystalline (NC) materials are prepared successfully by quenching melts under high pressure. The mean particle size is about 100 nm and the crystal structure is NaCl type. The mechanism of formation of the bulk NC alloy is explained: there is an increasing of the nucleation rate and a decrease in the growth rate of nuclei with increase of pressure during the solidification processes. The thermoelectric properties of Pb-Sn-Te bulk NC alloy are enhanced. This method is promising for producing thermoelectric materials with improved high-energy conversion efficiency

Surface Modifier-Free Organic-Inorganic Hybridization To Produce Optically Transparent and Highly Refractive Bulk Materials Composed of Epoxy Resins and ZrO2 Nanoparticles.

Science.gov (United States)

Enomoto, Kazushi; Kikuchi, Moriya; Narumi, Atsushi; Kawaguchi, Seigou

2018-04-25

Surface modifier-free hybridization of ZrO 2 nanoparticles (NPs) with epoxy-based polymers is demonstrated for the first time to afford highly transparent and refractive bulk materials. This is achieved by a unique and versatile hybridization via the one-pot direct phase transfer of ZrO 2 NPs from water to epoxy monomers without any aggregation followed by curing with anhydride. Three types of representative epoxy monomers, bisphenol A diglycidyl ether (BADGE), 3,4-epoxycyclohexylmethyl-3',4'-epoxycyclohexane carboxylate (CEL), and 1,3,5-tris(3-(oxiran-2-yl)propyl)-1,3,5-triazinane-2,4,6-trione (TEPIC), are used to produce transparent viscous dispersions. The resulting ZrO 2 NPs are thoroughly characterized using dynamic light scattering (DLS), transmission electron microscopy (TEM), Fourier transform infrared (FT-IR), and solid-state 13 C CP/MAS NMR measurements. The results from DLS and TEM analyses indicate nanodispersion of ZrO 2 into epoxy monomers as a continuous medium. A surface modification mechanism and the binding fashion during phase transfer are proposed based on the FT-IR and solid-state 13 C CP/MAS NMR measurements. Epoxy-based hybrid materials with high transparency and refractive index are successfully fabricated by heat curing or polymerizing a mixture of monomers containing epoxy-functionalized ZrO 2 NPs and methylhexahydrophthalic anhydride in the presence of a phosphoric catalyst. The TEM and small-angle X-ray scattering measurements of the hybrids show a nanodispersion of ZrO 2 in the epoxy networks. The refractive index at 594 nm ( n 594 ) increases up to 1.765 for BADGE-based hybrids, 1.667 for CEL-based hybrids, and 1.693 for TEPIC-based hybrids. Their refractive indices and Abbe's numbers are quantitatively described by the Lorentz-Lorenz effective medium expansion theory. Their transmissivity is also reasonably explained using Fresnel refraction, Rayleigh scattering, and the Lambert-Beer theories. This surface modifier-free hybridization

Iron zircon pigment synthesis: Proposal of a mixing index for the raw materials mixtures

International Nuclear Information System (INIS)

Zumaquero, E.; Ortsb, M.J.; Sanz, V.; Mestre, S.

2017-01-01

Iron zircon coral pigments are very interesting from an industrial point of view because of their high colouring power and their stability at high temperatures. However, the pigment's synthesis is particularly troublesome due to its specific reaction mechanism. As an encapsulated pigment it becomes very important how the raw materials are distributed in the reaction mixture. To evaluate the effectiveness of the mixing process, it would be convenient to define a parameter, that is the mixing index, to estimate the degree of homogeneity of the system. In the current investigation, a mixing index is proposed derived from the power spectrum of Fourier transform of scanning electron microscope (SEM) images of the raw material mixture. Concretely, the number of pixels in a certain range of values in the image of the power spectrum, seems to behave relatively well as mixing index. This index allows us to distinguish between samples with different zirconia and iron oxide used as precursors. The proposed mixing index seems to be related to the colouring power of the final pigment when the synthesis generates enough zircon to encapsulate hematite particles. [es

Elastic properties of a material composed of alternating layers of negative and positive Poisson's ratio

International Nuclear Information System (INIS)

Kocer, C.; McKenzie, D.R.; Bilek, M.M.

2009-01-01

The theory of elasticity predicts a variety of phenomena associated with solids that possess a negative Poisson's ratio. The fabrication of metamaterials with a 'designed' microstructure that exhibit a Poisson's ratio approaching the thermodynamic limits of 1/2 and -1 increases the likelihood of realising these phenomena for applications. In this work, we investigate the properties of a layered composite, with alternating layers of materials with negative and positive Poisson's ratio approaching the thermodynamic limits. Using the finite element method to simulate uniaxial loading and indentation of a free standing composite, we observed an increase in the resistance to mechanical deformation above the average value of the two materials. Even though the greatest increase in stiffness is gained as the thermodynamic limits are approached, a significant amount of added stiffness can be attained, provided that the Young's modulus of the negative Poisson's ratio material is not less than that of the positive Poisson's ratio material

High-Energy Laser Interaction with Gases, Droplets, and Bulk Liquids.

Science.gov (United States)

Jarzembski, Maurice Anthony

Breakdown threshold intensities (I_ {rm TH}) were measured as functions of wavelengths and pressure for air, He, Ar, and Xe using a Nd:YAG pulsed laser. Multiphoton absorption dominates in the UV and cascade collision ionization dominates in the IR; however, both can be affected by other electron gain and loss processes. Presence of droplets lowers breakdown of gases due to field enhancements. Breakdown is initiated either in the droplet material or in the gas. At lambda = 0.532mum for a 50 μm dia. water droplet in He, Ar, and air for p pressure. For droplet -in-Xe, at p pressure. For droplet-in-Xe, at p 140 Torr, breakdown occurs outside the droplet and is dependent on gas pressure. Pressure dependence of breakdown was observed for 120mum dia. water droplets in Ar at p > 400 Torr. The required intensity for breakdown of droplet depends on I_{ rm TH} of bulk liquid and the effective field enhancement created by the droplet. The I _{rm TH} of droplet-in-air provides an upper limit to the propagation of a high energy laser beam in the atmosphere containing particles. By geometrical optics approach, a significant field enhancement located at the critical ring region, encircling the axis of the sphere in the forward direction at angle theta_{c}, was discovered where nonlinear processes can occur. This was confirmed experimentally and by Mie theory. Field enhancements calculated at the critical ring for water droplets of different sizes agree well with measurements. For a droplet of given size and real refractive index, the effective field enhancement and the volume over which it occurs are two important factors governing the occurrence of breakdown in droplets for both off resonance and on resonance conditions. Measurements of wavelength dependence of breakdown showed that in the UV, I_{rm TH} for droplets and bulk liquids were comparable and lower by few orders of magnitude from that of air. Transmittance and reflectance of bulk liquids in the UV change with

Bulk-fill resin-based composites: an in vitro assessment of their mechanical performance.

Science.gov (United States)

Ilie, N; Bucuta, S; Draenert, M

2013-01-01

The study aimed to assess the mechanical performance of seven bulk-fill RBCs (Venus Bulk Fill, Heraeus Kulzer; SureFil SDR flow, Dentsply Caulk; x-tra base and x-tra fil, VOCO; Filtek Bulk Fill, 3M ESPE; SonicFill, Kerr; Tetric EvoCeram Bulk Fill, Ivoclar Vivadent) by determining their flexural strength (σ), reliability (Weibull parameter, m), flexural modulus (Eflexural), indentation modulus (YHU), Vickers hardness (HV), and creep (Cr). The significant highest flexural strengths were measured for SonicFill, x-tra base, and x-tra fil, while x-tra base, SureFil SDR flow, and Venus Bulk Fill showed the best reliability. The differences among the materials became more evident in terms of Eflexural and YHU, with x-tra fil achieving the highest values, while Filtek Bulk Fill and Venus Bulk Fill achieved the lowest. The enlarged depth of cure in bulk-fill RBCs seems to have been realized by enhancing the materials' translucency through decreasing the filler amount and increasing the filler size. The manufacturer's recommendation to finish a bulk-fill RBC restoration by adding a capping layer made of regular RBCs is an imperative necessity, since the modulus of elasticity and hardness of certain materials (SureFil SDR flow, Venus Bulk Fill, and Filtek Bulk Fill) were considerably below the mean values measured in regular nanohybrid and microhybrid RBCs. The class of bulk-fill RBCs revealed similar flexural strength values as the class of nanohybrid and microhybrid RBCs, and significantly higher values when compared to flowable RBCs. The modulus of elasticity (Eflexural), the indentation modulus (YHU), and the Vickers hardness (HV) classify the bulk-fill RBCs as between the hybrid RBCs and the flowable RBCs; in terms of creep, bulk-fill and the flowable RBCs perform similarly, both showing a significantly lower creep resistance when compared to the nanohybrid and microhybrid RBCs.

Application of the simulation of a tank capacity proposal for loading and unloading process of bulk material

Directory of Open Access Journals (Sweden)

Janka Šaderová

2012-12-01

Full Text Available n this paper, the algorithm is given - how to design a tankfor bulk materials. An important part of the proposal is to setthe loading and unloading of a tank, which is also closely related to the proposal of its capacity and volume. Loading and unloadingprocess is dependent on several factors but the main are: method and speed of loading which represents the parameter - hour powerof loading device (e.g. continuous by a conveyor belt, method andspeed of unloading (continuousor at intervals and a typeand capacity of means of transport, in which the material loading (truck, rail car, conveyor belt system. The paper presents twomethods for determination of the loadingand unloading process - the graphic method and determination during the simulation -creating a simulation model.

Standard practice for bulk sampling of liquid uranium hexafluoride

CERN Document Server

American Society for Testing and Materials. Philadelphia

2001-01-01

1.1 This practice covers methods for withdrawing representative samples of liquid uranium hexafluoride (UF6) from bulk quantities of the material. Such samples are used for determining compliance with the applicable commercial specification, for example Specification C787 and Specification C996. 1.2 It is assumed that the bulk liquid UF6 being sampled comprises a single quality and quantity of material. This practice does not address any special additional arrangements that might be required for taking proportional or composite samples, or when the sampled bulk material is being added to UF6 residues already in a container (“heels recycle”). 1.3 The number of samples to be taken, their nominal sample weight, and their disposition shall be agreed upon between the parties. 1.4 The scope of this practice does not include provisions for preventing criticality incidents. 1.5 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of th...

Thermal, spectral, and surface properties of LED light-polymerized bulk fill resin composites.

Science.gov (United States)

Pişkin, Mehmet Burçin; Atalı, Pınar Yılmaz; Figen, Aysel Kantürk

2015-02-01

The aim of this study was to evaluate the thermal, spectral, and surface properties of four different bulk fill materials – SureFil SDR (SDR, Dentsplay DETREY), QuixFil (QF, Dentsplay DETREY), X-tra base (XB, Voco) X-tra fil (XF, Voco) – polymerized by light-emitting diode (LED). Resin matrix, filler type, size and amount, and photoinitiator types influence the degree of conversion. LED-cured bulk fill composites achieved sufficient polymerization. Scanning electron microscope (SEM) analysis revealed different patterns of surface roughness, depending on the composite material. Bulk fill materials showed surface characteristics similar to those of nanohybrid composites. Based on the thermal analysis results, glass transition (T(g)) and initial degradation (T(i)) temperatures changed depending on the bulk fill resin composites.

Design of a New Sensor for Determination of the Effects of Tractor Field Usage in Southern Spain: Soil Sinkage and Alterations in the Cone Index and Dry Bulk Density

Directory of Open Access Journals (Sweden)

Diego L. Valera

2012-10-01

Full Text Available Variations in sinkage and cone index are of crucial importance when planning fieldwork, and for determining the trafficability of farm machinery. Many studies have highlighted the link between higher values of these parameters and dramatic decreases in crop yield. Variations in the dry bulk density and cone index of clayey soil in Southern Spain were measured following each of five successive passes over the same land with the three types of tractor most widely used in the area (tracked, two-wheel drive and four-wheel drive. In addition, sinkage (rut depth of the running gear was measured using a laser microrelief profile meter. This device, which integrates three sensors, was specifically designed for these experiments, as was an electrical penetrometer to determine the cone index, and both instruments proved reliable and accurate in the field. The main goal of this study was to design, manufacture and test these new devices. The first pass caused most soil alteration when compared to successive passes for all types of tractor tested and soil conditions prevailing during the tests. (Heavier four-wheel drive tractors were found to cause greater soil damage (sinkage, cone index and dry bulk density than two-wheel drive and track tractors. There was no statistically significant difference between the two latter types. The greatest alterations were recorded in the top 10 cm of the soil. The results show that soil compaction should be avoided as much as possible. This can be achieved by ensuring that tractors always travel along the same tracks, especially in the wet season. At present these aspects are not considered by farmers in this area.

Induction detection of concealed bulk banknotes

International Nuclear Information System (INIS)

Fuller, Christopher; Chen, Antao

2011-01-01

Bulk cash smuggling is a serious issue that has grown in volume in recent years. By building on the magnetic characteristics of paper currency, induction sensing is found to be capable of quickly detecting large masses of banknotes. The results show that this method is effective in detecting bulk cash through concealing materials such as plastics, cardboards, fabrics and aluminum foil. The significant difference in the observed phase between the received signals caused by conducting materials and ferrite compounds, found in banknotes, provides a good indication that this process can overcome the interference by metal objects in a real sensing application. This identification strategy has the potential to not only detect the presence of banknotes, but also the number, while still eliminating false positives caused by metal objects

Study on Brewster angle thin film polarizer using hafnia-silica mixture as high-refractive-index material

Science.gov (United States)

Xu, Nuo; Zhu, Meiping; Sun, Jian; Chai, Yingjie; Kui, Yi; Zhao, Yuanan; Shao, Jianda

2018-02-01

Two kinds of polarizer coatings were prepared by electron beam evaporation, using HfO2-SiO2 mixture and HfO2 as the high-refractive-index materials, respectively. The HfO2-SiO2 mixture layer was implemented by coevaporating SiO2 and metal Hf, the materials were deposited at an oxygen atmosphere to achieve stoichiometric coatings. The certain HfO2 and SiO2 content ratio is controlled by adjusting the deposition rate of HfO2 and SiO2 using individual quartz crystal monitor. The spectral performance, surface and interfacial properties, as well as the laser-induced damage performance were studied and compared. Comparing with polarizer coating using HfO2 as high-refractive-index material, the polarizer coating using HfO2-SiO2 mixture as high-refractive-index material shows better performance with broader polarizing bandwidth, lower surface roughness, better interfacial property while maintaining high laser-induced damage threshold.

The projected relative index of consequence equivalence of transport of radioactive materials

International Nuclear Information System (INIS)

Nandakumar, A.N.

1999-01-01

The need exists for defining a unit risk factor to enable analysis to make a proper decision when faced with many options relating to the transport of radioactive materials between sites. A method is discussed for deriving such a factor with reference to the collective dose receivable due to the transport of radioactive material incidental to the production of one GWe.a of nuclear power. This quantity would enable the analyst to determine the projected relative index of consequence equivalence (PRICE) for the transport of various types of radioactive materials. (author)

Curing characteristics of flowable and sculptable bulk-fill composites

OpenAIRE

Miletic, Vesna; Pongpruenska, Pong; De Munck, Jan; Brooks, Neil R; Van Meerbeek, Bart

2016-01-01

OBJECTIVES: The aim of this study was to determine and correlate the degree of conversion (DC) with Vickers hardness (VH) and translucency parameter (TP) with the depth of cure (DoC) of five bulk-fill composites. MATERIALS AND METHODS: Six specimens per group, consisting of Tetric EvoCeram Bulk Fill ("TEC Bulk," Ivoclar Vivadent), SonicFill (Kerr), SDR Smart Dentin Replacement ("SDR," Dentsply), Xenius base ("Xenius," StickTech; commercialized as EverX Posterior, GC), Filtek Bul...

Enhanced bulk conductivity and bipolar transport in mixtures of MoOx and organic hole transport materials

International Nuclear Information System (INIS)

Tian, Baolin; Ban, Dayan; Aziz, Hany

2013-01-01

We study the conductivity of thin films of molybdenum oxide (MoO x ) mixed with an organic hole transport material, such as N,N′-bis(naphthalen-1-yl)-N,N′-bis (phenyl)benzidine or 4′,4″-tri(N-carbazolyl)triphenylamine, in lateral test devices. Contrary to previous reports, the conductivity of the mixture is found to exceed that of neat MoO x , exhibiting ∼ 5 orders of magnitude higher conductivity in comparison to the neat films. Studies also show that the mixing enhances both hole and electron transport. The higher conductivity may be attributed to a higher concentration of “free” carriers in the mixture, as a result of the formation of a charge transfer complex between the MoO x and the hole transport material. The findings shed light on the potential of hybrid composites of inorganic and organic materials in realizing enhanced conductivity. - Highlights: • We investigate the conductivity of mixtures of MoO x and hole transport material (HTM). • Materials are studied in lateral devices instead of conventional vertical devices. • Mixing MoO x with HTM brings > 5 orders of magnitude increase in bulk conductivity. • The mixture of MoO x and HTM enhances both hole and electron transport

Reduction of damage threshold in dielectric materials induced by negatively chirped laser pulses

International Nuclear Information System (INIS)

Louzon, E.; Henis, Z.; Pecker, S.; Ehrlich, Y.; Fisher, D.; Fraenkel, M.; Zigler, A.

2005-01-01

The threshold fluence for laser induced damage in wide band gap dielectric materials, fused silica and MgF 2 , is observed to be lower by up to 20% for negatively (down) chirped pulses than for positively (up) chirped, at pulse durations ranging from 60 fs to 1 ps. This behavior of the threshold fluence for damage on the chirp direction was not observed in semiconductors (silicon and GaAs). Based on a model including electron generation in the conduction band and Joule heating, it is suggested that the decrease in the damage threshold for negatively chirped pulse is related to the dominant role of multiphoton ionization in wide gap materials

Multi-band Microwave Antennas and Devices based on Generalized Negative-Refractive-Index Transmission Lines

Science.gov (United States)

Ryan, Colan Graeme Matthew

Focused on the quad-band generalized negative-refractive-index transmission line (G-NRI-TL), this thesis presents a variety of novel printed G-NRI-TL multi-band microwave device and antenna prototypes. A dual-band coupled-line coupler, an all-pass G-NRI-TL bridged-T circuit, a dual-band metamaterial leaky-wave antenna, and a multi-band G-NRI-TL resonant antenna are all new developments resulting from this research. In addition, to continue the theme of multi-band components, negative-refractive-index transmission lines are used to create a dual-band circularly polarized transparent patch antenna and a two-element wideband decoupled meander antenna system. High coupling over two independently-specified frequency bands is the hallmark of the G-NRI-TL coupler: it is 0.35lambda0 long but achieves approximately -3 dB coupling over both bands with a maximum insertion loss of 1 dB. This represents greater design flexibility than conventional coupled-line couplers and less loss than subsequent G-NRI-TL couplers. The single-ended bridged-T G-NRI-TL offers a metamaterial unit cell with an all-pass magnitude response up to 8 GHz, while still preserving the quad-band phase response of the original circuit. It is shown how the all-pass response leads to wider bandwidths and improved matching in quad-band inverters, power dividers, and hybrid couplers. The dual-band metamaterial leaky-wave antenna presented here was the first to be reported in the literature, and it allows broadside radiation at both 2 GHz and 6 GHz without experiencing the broadside stopband common to conventional periodic antennas. Likewise, the G-NRI-TL resonant antenna is the first reported instance of such a device, achieving quad-band operation between 2.5 GHz and 5.6 GHz, with a minimum radiation efficiency of 80%. Negative-refractive-index transmission line loading is applied to two devices: an NRI-TL meander antenna achieves a measured 52% impedance bandwidth, while a square patch antenna incorporates

Bulk metallic glass matrix composites

International Nuclear Information System (INIS)

Choi-Yim, H.; Johnson, W.L.

1997-01-01

Composites with a bulk metallic glass matrix were synthesized and characterized. This was made possible by the recent development of bulk metallic glasses that exhibit high resistance to crystallization in the undercooled liquid state. In this letter, experimental methods for processing metallic glass composites are introduced. Three different bulk metallic glass forming alloys were used as the matrix materials. Both ceramics and metals were introduced as reinforcement into the metallic glass. The metallic glass matrix remained amorphous after adding up to a 30 vol% fraction of particles or short wires. X-ray diffraction patterns of the composites show only peaks from the second phase particles superimposed on the broad diffuse maxima from the amorphous phase. Optical micrographs reveal uniformly distributed particles in the matrix. The glass transition of the amorphous matrix and the crystallization behavior of the composites were studied by calorimetric methods. copyright 1997 American Institute of Physics

Evolution of polarization in an atomic vapour with negative refractive index

International Nuclear Information System (INIS)

Zhuang Fei; Shen Jianqi

2006-01-01

A three-level Lambda-configuration atomic vapour may exhibit simultaneously negative permittivity and permeability in the optical frequency band, and an isotropic left-handed vapour medium could therefore be realized within the framework of quantum optics. One of the most remarkable features of the present scheme is that both the refractive index and the photon helicity reversal inside the vapour can be controllably manipulated by an external coupling light field. The phenomenological Hamiltonian that describes the process of helicity reversal is constructed and the time-dependent Schroedinger equation governing the time evolution of the polarization states of the lightwave is solved by means of the Lewis-Riesenfeld invariant theory. The transition between the polarization states (and hence the accompanied photon helicity reversal), which is exactly analogous to the transition operation between bits in digital circuit, may be valuable for the development of new techniques in quantum optics and would have potential applications in information technology

A Novel Approach to Forecasting the Bulk Freight Market

Directory of Open Access Journals (Sweden)

Vangelis Tsioumas

2017-03-01

Full Text Available The fast-paced and ever changing freight market compels maritime executives to use sound forecasting tools. This paper aims to enhance the forecasting accuracy of the Baltic Dry Index (BDI by means of developing a multivariate Vector Autoregressive model with exogenous variables (VARX. The proposed model incorporates the Chinese steel production, the dry bulk fleet development and a new composite indicator, the Dry Bulk Economic Climate Index (DBECI. The predictive power of this approach is evaluated against a univariate ARIMA framework, which serves as a benchmark model. The selection of explanatory variables and the model specification are validated using a series of pertinent tests. The results demonstrate that the VARX model outperforms the ARIMA approach, suggesting that the selected independent variables can substantially improve the accuracy of BDI forecasts. The present study is of interest to maritime practitioners, as it provides useful insights into the direction of the freight market and allows them to make informed decisions.

Band structure of comb-like photonic crystals containing meta-materials

Science.gov (United States)

Weng, Yi; Wang, Zhi-Guo; Chen, Hong

2007-09-01

We study the transmission properties and band structure of comb-like photonic crystals (PC) with backbones constructed of meta-materials (negative-index materials) within the frame of the interface response theory. The result shows the existence of a special band gap at low frequency. This gap differs from the Bragg gaps in that it is insensitive to the geometrical scaling and disorder. In comparison with the zero-average-index gap in one-dimensional PC made of alternating positive- and negative-index materials, the gap is obviously deeper and broader, given the same system parameters. In addition, the behavior of its gap-edges is also different. One gap-edge is decided by the average permittivity whereas the other is only subject to the changing of the permeability of the backbone. Due to this asymmetry of the two gap-edges, the broadening of the gap could be realized with much freedom and facility.

Direct Electrospray Printing of Gradient Refractive Index Chalcogenide Glass Films.

Science.gov (United States)

Novak, Spencer; Lin, Pao Tai; Li, Cheng; Lumdee, Chatdanai; Hu, Juejun; Agarwal, Anuradha; Kik, Pieter G; Deng, Weiwei; Richardson, Kathleen

2017-08-16

A spatially varying effective refractive index gradient using chalcogenide glass layers is printed on a silicon wafer using an optimized electrospray (ES) deposition process. Using solution-derived glass precursors, IR-transparent Ge 23 Sb 7 S 70 and As 40 S 60 glass films of programmed thickness are fabricated to yield a bilayer structure, resulting in an effective gradient refractive index (GRIN) film. Optical and compositional analysis tools confirm the optical and physical nature of the gradient in the resulting high-optical-quality films, demonstrating the power of direct printing of multimaterial structures compatible with planar photonic fabrication protocols. The potential application of such tailorable materials and structures as they relate to the enhancement of sensitivity in chalcogenide glass based planar chemical sensor device design is presented. This method, applicable to a broad cross section of glass compositions, shows promise in directly depositing GRIN films with tunable refractive index profiles for bulk and planar optical components and devices.

Characteristics of low polymerization shrinkage flowable resin composites in newly-developed cavity base materials for bulk filling technique.

Science.gov (United States)

Nitta, Keiko; Nomoto, Rie; Tsubota, Yuji; Tsuchikawa, Masuji; Hayakawa, Tohru

2017-11-29

The purpose of this study was to evaluate polymerization shrinkage and other physical properties of newly-developed cavity base materials for bulk filling technique, with the brand name BULK BASE (BBS). Polymerization shrinkage was measured according to ISO/FDIS 17304. BBS showed the significantly lowest polymerization shrinkage and significantly higher depth of cure than conventional flowable resin composites (p<0.05). The Knoop hardness, flexural strength and elastic modulus of that were significantly lower than conventional flowable resin composites (p<0.05). BBS had the significantly greatest filler content (p<0.05). SEM images of the surface showed failure of fillers. The lowest polymerization shrinkage was due to the incorporation of a new type of low shrinkage monomer, which has urethane moieties. There were no clear correlations between inorganic filler contents and polymerization shrinkage, flexural strength and elastic modulus. In conclusion, the low polymerization shrinkage of BBS will be useful for cavity treatment in dental clinics.

Structural determinants in the bulk heterojunction.

Science.gov (United States)

Acocella, Angela; Höfinger, Siegfried; Haunschmid, Ernst; Pop, Sergiu C; Narumi, Tetsu; Yasuoka, Kenji; Yasui, Masato; Zerbetto, Francesco

2018-02-21

Photovoltaics is one of the key areas in renewable energy research with remarkable progress made every year. Here we consider the case of a photoactive material and study its structural composition and the resulting consequences for the fundamental processes driving solar energy conversion. A multiscale approach is used to characterize essential molecular properties of the light-absorbing layer. A selection of bulk-representative pairs of donor/acceptor molecules is extracted from the molecular dynamics simulation of the bulk heterojunction and analyzed at increasing levels of detail. Significantly increased ground state energies together with an array of additional structural characteristics are identified that all point towards an auxiliary role of the material's structural organization in mediating charge-transfer and -separation. Mechanistic studies of the type presented here can provide important insights into fundamental principles governing solar energy conversion in next-generation photovoltaic devices.

Induction detection of concealed bulk banknotes

Science.gov (United States)

Fuller, Christopher; Chen, Antao

2012-06-01

The smuggling of bulk cash across borders is a serious issue that has increased in recent years. In an effort to curb the illegal transport of large numbers of paper bills, a detection scheme has been developed, based on the magnetic characteristics of bank notes. The results show that volumes of paper currency can be detected through common concealing materials such as plastics, cardboard, and fabrics making it a possible potential addition to border security methods. The detection scheme holds the potential of also reducing or eliminating false positives caused by metallic materials found in the vicinity, by observing the stark difference in received signals caused by metal and currency. The detection scheme holds the potential to detect for both the presence and number of concealed bulk notes, while maintaining the ability to reduce false positives caused by metal objects.

The influence of irradiation potential on the degree of conversion and mechanical properties of two bulk-fill flowable RBC base materials.

Science.gov (United States)

Finan, Leah; Palin, William M; Moskwa, Natalia; McGinley, Emma Louise; Fleming, Garry J P

2013-08-01

To assess the depth of cure claims of two bulk-fill flowable RBC bases (SDR and x-tra base) using Fourier transform infrared (FTIR) spectroscopy, biaxial flexure strength (BFS), and Vickers hardness number (VHN) for specimen depths of 8mm (in 1mm increments). The degree of conversion (DC) was measured by monitoring the peak height (6164cm(-1)) of specimens (11.0±0.1mm diameter, 1.0±0.1mm thickness) during light irradiation for 20s using a quartz tungsten halogen light curing unit at 650±26mW/cm(2). DC was measured up to 120s post irradiation and repeated (n=3) for irradiation depths up to 8mm (in 1mm increments). Further series (n=20) of eight discs were prepared, stacked, light irradiated and numbered from one to eight (distance from the LCU). The specimens were stored at 37±1°C for 24h and BFS tested with the fracture fragments used to determine the VHN for each specimen. X-tra base can be irradiated to 8mm without a change in DC, something the SDR material cannot claim. However, the DC results confirm both bulk-fill flowable RBC bases have a depth of cure in excess of 4mm. One-way ANOVAs of BFS and VHN data showed significant differences between irradiation depths for x-tra base and SDR with increasing irradiation depth (4mm) resulting in significant reductions in mean BFS and VHN. The claims that the bulk-fill flowable RBC bases have a depth of cure in excess of 4mm can be confirmed but the differing chemistry of the resin formulations and filler characteristics contribute to significant differences in DC, BFS and VHN data between the two materials tested. Copyright © 2013 Academy of Dental Materials. Published by Elsevier Ltd. All rights reserved.

The impact of compaction, moisture content, particle size and type of bulking agent on initial physical properties of sludge-bulking agent mixtures before composting.

Science.gov (United States)

Huet, J; Druilhe, C; Trémier, A; Benoist, J C; Debenest, G

2012-06-01

This study aimed to experimentally acquire evolution profiles between depth, bulk density, Free Air Space (FAS), air permeability and thermal conductivity in initial composting materials. The impact of two different moisture content, two particle size and two types of bulking agent on these four parameters was also evaluated. Bulk density and thermal conductivity both increased with depth while FAS and air permeability both decreased with it. Moreover, depth and moisture content had a significant impact on almost all the four physical parameters contrary to particle size and the type of bulking agent. Copyright © 2012 Elsevier Ltd. All rights reserved.

Home composting using different ratios of bulking agent to food waste.

Science.gov (United States)

Guidoni, Lucas Lourenço Castiglioni; Marques, Roger Vasques; Moncks, Rodrigo Bilhalva; Botelho, Fabiana Torma; da Paz, Matheus Francisco; Corrêa, Luciara Bilhalva; Corrêa, Érico Kunde

2018-02-01

The negative environmental impacts associated with home composting may be due to the absence of a defined operation criteria for the degradation process. In addition to the potentially low environmental impact in terms of energy and water usage, which is minimal to the manufacture of the composting unit and avoiding the processing and transportation of waste or byproduct, composting at home can also promote a reduction in the emission of unpleasant gases. The proportion of the food waste and bulking agents in the composting mixture may be decisive to fulfill good practices of waste stabilization. The aim of this study was to investigate how different ratios of bulking agent and organic household waste can affect the progress and outcome of the composting process. Three treatments, varying in the ratio of rice husk: raw fruit and vegetable leftovers (70:30, 50:50, 30:70; v:v) were used in a home composting system on a pilot scale. Results show that the proportion of starting materials used in the composting mixture influenced the degradation of organic matter, nitrogen dynamics of the process and its toxicity on germinating plants. The proportions with greater amounts of food waste had higher concentrations of mineral matter, higher peak temperature, and a better initial carbon-to-nitrogen ratio, while the proportion containing 70% of bulking agent lacked odors and leachate generation and showed a low nitrogen loss. A higher proportion of food waste presented better conditions for microbiological development and less time to obtain characteristics of matured composts. A higher proportion of bulking agents resulted in favorable conditions for household handling and less potential for environmental impacts. Copyright © 2017 Elsevier Ltd. All rights reserved.

Positive or negative Poynting effect? The role of adscititious inequalities in hyperelastic materials

KAUST Repository

Mihai, L. A.

2011-08-10

Motivated by recent experiments on biopolymer gels whereby the reverse of the usual (positive) Poynting effect was observed, we investigate the effect of the so-called \\'adscititious inequalities\\' on the behaviour of hyperelastic materials subject to shear. We first demonstrate that for homogeneous isotropic materials subject to pure shear, the resulting deformation consists of a triaxial stretch combined with a simple shear in the direction of the shear force if and only if the Baker-Ericksen inequalities hold. Then for a cube deformed under pure shear, the positive Poynting effect occurs if the \\'sheared faces spread apart\\', whereas the negative Poynting effect is obtained if the \\'sheared faces draw together\\'. Similarly, under simple shear deformation, the positive Poynting effect is obtained if the \\'sheared faces tend to spread apart\\', whereas the negative Poynting effect occurs if the \\'sheared faces tend to draw together\\'. When the Poynting effect occurs under simple shear, it is reasonable to assume that the same sign Poynting effect is btained also under pure shear. Since the observation of the negative Poynting effect in semiflexible biopolymers implies that the (stronger) empirical inequalities may not hold, we conclude that these inequalities must not be imposed when such materials are described. © 2011 The Royal Society.

Studies of nonlinear femtosecond pulse propagation in bulk materials

Science.gov (United States)

Eaton, Hilary Kaye

2000-10-01

Femtosecond pulse lasers are finding widespread application in a variety of fields including medical research, optical switching and communications, plasma formation, high harmonic generation, and wavepacket formation and control. As the number of applications for femtosecond pulses increases, so does the need to fully understand the linear and nonlinear processes involved in propagating these pulses through materials under various conditions. Recent advances in pulse measurement techniques, such as frequency-resolved optical gating (FROG), allow measurement of the full electric field of the pulse and have made detailed investigations of short- pulse propagation effects feasible. In this thesis, I present detailed experimental studies of my work involving nonlinear propagation of femtosecond pulses in bulk media. Studies of plane-wave propagation in fused silica extend the SHG form of FROG from a simple pulse diagnostic to a useful method of interrogating the nonlinear response of a material. Studies of nonlinear propagation are also performed in a regime where temporal pulse splitting occurs. Experimental results are compared with a three- dimensional nonlinear Schrödinger equation. This comparison fuels the development of a more complete model for pulse splitting. Experiments are also performed at peak input powers above those at which pulse splitting is observed. At these higher intensities, a broadband continuum is generated. This work presents a detailed study of continuum behavior and power loss as well as the first near-field spatial- spectral measurements of the generated continuum light. Nonlinear plane-wave propagation of short pulses in liquids is also investigated, and a non-instantaneous nonlinearity with a surprisingly short response time of 10 fs is observed in methanol. Experiments in water confirm that this effect in methanol is indeed real. Possible explanations for the observed effect are discussed and several are experimentally rejected. This

Temporary surface passivation for characterisation of bulk defects in silicon : a review

OpenAIRE

Grant, Nicholas E.; Murphy, John D.

2017-01-01

Accurate measurements of the bulk minority carrier lifetime in high-quality silicon materials is challenging due to the influence of surface recombination. Conventional surface passivation processes such as thermal oxidation or dielectric deposition often modify the bulk lifetime significantly before measurement. Temporary surface passivation processes at room or very low temperatures enable a more accurate measurement of the true bulk lifetime, as they limit thermal reconfiguration of bulk d...

RESEARCHES REGARDING USE OF TEXTILE MATERIALS FOR THERMAL INSULATION AT NEGATIVE TEMPERATURES

Directory of Open Access Journals (Sweden)

IOSUB Andrei

2014-05-01

Full Text Available Using thermal insulation in negative temperature acts to reduce heat flow to the cooled space or to objects that have a temperature below ambient temperature. To achieve economic operation of the space to be cooled insulation thickness and quality is an important factor. In this article we want to compare three products used in thermal insulation at negative temperatures: expanded polystyrene, non-woven and wool coats. The materials will be tested with a mechanical vapor compression refrigerator capable of producing temperatures in the range +4 .. -35 ° C, managed by a programmer Dixel capable of recording values between +40. .. -60 °C. Refrigeration insulation enclosure was made with 100 mm expanded polystyrene. On one side of the enclosure will be a cut of 250 * 250 mm, chosen in a central position where the material will be introduced to be tested. The dimensions of the samples are 250 * 250 * 60 mm. To check the insulation properties of materials it will be used a temperature logger capable of recording with two probes temperatures between +125...-40° C. One of the probes will be inserted inside the refrigerator and the second probe will be positioned to the outside of the test material adhered to an aluminum plate, in order to read a average temperature. The difference in thickness of the insulation shall be filled with non-woven material. Hardening the assembly will be made using a 6 mm thick OSB board. The materials will be tested in an identical ambient temperature and humidity.

Assessment of Real-Time Compaction Quality Test Indexes for Rockfill Material Based on Roller Vibratory Acceleration Analysis

Directory of Open Access Journals (Sweden)

Tianbo Hua

2018-01-01

Full Text Available Compaction quality is directly related to the structure and seepage stability of a rockfill dam. To timely and accurately test the compaction quality of the rockfill material, four real-time test indexes were chosen to characterize the soil compaction degree based on the analysis of roller vibratory acceleration, including acceleration peak value (ap, acceleration root mean square value (arms, crest factor value (CF, and compaction meter value (CMV. To determine which of these indexes is the most appropriate, a two-part field compaction experiment was conducted using a vibratory roller in different filling zones of the dam body. Data on rolling parameters, real-time test indexes, and compaction quality indexes were collected to perform statistical regression analyses. Combined with the spectrum analysis of the acceleration signal, it was found that the CF index best characterizes the compaction degree of the rockfill material among the four indexes. Furthermore, the quantitative relations between the real-time index and compaction quality index were established to determine the control criterion of CF, which can instruct the site work of compaction quality control in the rockfill rolling process.

4D and 2D superconformal index with surface operator

Science.gov (United States)

Nakayama, Yu

2011-08-01

We study the superconformal index of the mathcal{N} = 4 super-Yang-Milles theory on S 3 × S 1 with the half BPS superconformal surface operator (defect) inserted at the great circle of S 3. The half BPS superconformal surface operators preserve the same supersymmetry as well as the symmetry of the chemical potential used in the definition of the superconformal index, so the structure and the parameterization of the superconformal index remain unaffected by the presence of the surface operator. On the surface defect, a two-dimensional (4, 4) superconformal field theory resides, and the four-dimensional super-conformal index may be regarded as a superconformal index of the two-dimensional (4, 4) superconformal field theory coupled with the four-dimensional bulk system. We construct the matrix model that computes the superconformal index with the surface operator when it couples with the bulk mathcal{N} = 4 super-Yang-Milles theory through the defect hypermultiplets on it.

Negative Index Materials and Plasmonic Antennas Based Nanocouplers

DEFF Research Database (Denmark)

Andryieuski, Andrei

. The metallization is based on silver reduction from the silver-ammonia complex with formaldehyde. Continuous and smooth silver layer can be deposited starting from 30 nm. The technology can be used for the complex photonic structures fabrication for the infrared frequencies. The coupling effects between...... metamaterials monolayers are investigated. It is shown that some metamaterials can be treated as homogeneous in the resonant frequency region, but some cannot at any value of the metamaterials period. The quantitative homogenization condition is formulated. Five types of the nanoantenna based couplers...

Octonacci photonic crystals with negative refraction index materials

Science.gov (United States)

Brandão, E. R.; Vasconcelos, M. S.; Anselmo, D. H. A. L.

2016-12-01

We investigate the optical transmission spectra for s-polarized (TE) and p-polarized (TM) waves in one-dimensional photonic quasicrystals on a quasiperiodic multilayer structure made up by alternate layers of SiO2 and metamaterials, organized by following the Octonacci sequence. Maxwell's equations and the transfer-matrix technique are used to derive the transmission spectra for the propagation of normally and obliquely incident optical fields. We assume Drude-Lorentz-type dispersive response for the dielectric permittivity and magnetic permeability of the metamaterials. For normally incident waves, we observe that the spectra does not have self-similar behavior or mirror symmetry and it also features the absence of optical band gap. Also for normally incident waves, we show regions of full transmittance when the incident angle θC = 0° in a particular frequency range.

Three-Dimensionally Isotropic Negative Refractive Index Materials from Block Copolymer Self-Assembled Chiral Gyroid Networks

KAUST Repository

Hur, Kahyun

2011-10-17

Metamaterials are engineered artificial materials that offer new functionalities such as super-resolution imaging and cloaking. Calculations of the photonic properties of three-dimensionally isotropic metamaterials with cubic double gyroid and alternating gyroid morphologies from block copolymer self-assembly are presented.

Contribution of bulk mass spectrometry isotopic analysis to characterization of materials in the framework of CMX-4

International Nuclear Information System (INIS)

Kuchkin, A.; Stebelkov, V.; Zhizhin, K.; Lierse von Gostomski, Ch.; Kardinal, Ch.; Loi, E.; Keegan, E.; Kristo, M.J.

2018-01-01

Seven laboratories used the results of bulk uranium isotopic analysis by either inductively coupled plasma mass spectrometry (ICP-MS) or thermal ionization mass spectrometry (TIMS) for characterization of the samples in the Nuclear Forensic International Technical Working Group fourth international collaborative material exercise, CMX-4. Comparison of the measured isotopic compositions of uranium in three exercise samples is implemented for identifying any differences or similarities between the samples. The role of isotopic analyses in the context of a real nuclear forensic investigation is discussed. Several limitations in carrying out ICP-MS or TIMS analysis in CMX-4 are noted. (author)

Gamma-ray attenuation to measure water contents and/or bulk densities of porous materials

International Nuclear Information System (INIS)

Ferraz, E.S.B.

1983-01-01

Attenuation of gamma radiation during transmission through soil and porous materials has been used for approximately three decades as a method for determining volumetric water content, theta, and bulk density, rho. This method is particularly suited for laboratory determinations of theta and rho in soil columns but it also has been used with success under field conditions. Measurements of attentuation of a collimated beam of monoernergetic gamma-rays has been used successfully by many investigators to provide rapid, non-destructive determinations for small volumes of soil. For stable soils, i.e. soils which do not swell upon wetting or shrink upon drying, rho may be assumed to remain constant during water flow through the soil, and thus changes in intensity or transmitted radiation may be attributed to changes in water content, theta. However, for unstable soils, the dry bulk density is subject to change with time during water flow through the soil and cannot be assumed to be a constant. Several investigators have utilized either a single beam of dual-energy gamma photons or two separate monoenergetic photon beams with greatly different energies to simultaneously determine theta and rho in these soils. A general review of gamma-ray attenuation methods for determining theta and rho in laboratory soil cores and in field soil profiles is reported in this paper. Theoretical equations for transmission and attenuation of gamma radiation in soils are presented for both single and double beams of gamma photons. Sensitivity, precision, accuracy, and experimental errors for the method are evaluated and discussed with respect to the theory. (author)

High-precision Mg isotope measurements of terrestrial and extraterrestrial material by HR-MC-ICPMS—implications for the relative and absolute Mg isotope composition of the bulk silicate Earth

DEFF Research Database (Denmark)

Bizzarro, Martin; Paton, Chad; Larsen, Kirsten Kolbjørn

2011-01-01

-isotope composition for Earth’s mantle – and hence that of the bulk silicate Earth – to be 25Mg/24Mg 1/4 0.126896 ¿ 0.000025 and 26Mg/24Mg 1/4 0.139652 ¿ 0.000033. Given the restricted range of m25Mg obtained for bulk planetary material by the sample-standard bracketing technique and the excellent agreement between...

Randall-Sundrum model with λ<0 and bulk brane viscosity

International Nuclear Information System (INIS)

Lepe, Samuel; Pena, Francisco; Saavedra, Joel

2008-01-01

We study the effect of the inclusion of bulk brane viscosity on brane world (BW) cosmology in the framework of the Eckart's theory, we focus in the Randall-Sundrum model with negative tension on the brane

Role of shape of hole in transmission and negative refractive index of sandwiched metamaterials

International Nuclear Information System (INIS)

Zhong Min; Ye Yong-Hong

2014-01-01

Transmission and negative refractive index (NRI) of metal—dielectric—metal (MDM) sandwiched metamaterial perforated with four kinds of shapes of holes are numerically studied. Results indicate that positions of all transmission peaks of these kinds of holes are sensitive to the shape of the hole. Under the same conditions, the circular hole can obtain the maximum NRI and the rectangular hole can obtain the maximum frequency bandwidth of NRI. Moreover, the figure of merit (FOM) of the circular hole is the maximum too. As a result, we can obtain a higher NRI and FOM metamaterial by drilling circular hole arrays on MDM metamaterial. (electromagnetism, optics, acoustics, heat transfer, classical mechanics, and fluid dynamics)

Permanent magnet with MgB{sub 2} bulk superconductor

Energy Technology Data Exchange (ETDEWEB)

Yamamoto, Akiyasu, E-mail: yamamoto@appchem.t.u-tokyo.ac.jp [The University of Tokyo, 7-3-1 Hongo, Bunkyo, Tokyo 113-8656 (Japan); JST-PRESTO, 4-1-8 Honcho, Kawaguchi, Saitama 332-0012 (Japan); Ishihara, Atsushi; Tomita, Masaru [Railway Technical Research Institute, 2-8-38 Hikari, Kokubunji, Tokyo 185-8540 (Japan); Kishio, Kohji [The University of Tokyo, 7-3-1 Hongo, Bunkyo, Tokyo 113-8656 (Japan)

2014-07-21

Superconductors with persistent zero-resistance currents serve as permanent magnets for high-field applications requiring a strong and stable magnetic field, such as magnetic resonance imaging. The recent global helium shortage has quickened research into high-temperature superconductors (HTSs)—materials that can be used without conventional liquid-helium cooling to 4.2 K. Herein, we demonstrate that 40-K-class metallic HTS magnesium diboride (MgB{sub 2}) makes an excellent permanent bulk magnet, maintaining 3 T at 20 K for 1 week with an extremely high stability (<0.1 ppm/h). The magnetic field trapped in this magnet is uniformly distributed, as for single-crystalline neodymium-iron-boron. Magnetic hysteresis loop of the MgB{sub 2} permanent bulk magnet was determined. Because MgB{sub 2} is a simple-binary-line compound that does not contain rare-earth metals, polycrystalline bulk material can be industrially fabricated at low cost and with high yield to serve as strong magnets that are compatible with conventional compact cryocoolers, making MgB{sub 2} bulks promising for the next generation of Tesla-class permanent-magnet applications.

Microwave processed bulk and nano NiMg ferrites: A comparative study on X-band electromagnetic interference shielding properties

Energy Technology Data Exchange (ETDEWEB)

Chandra Babu Naidu, K., E-mail: chandrababu954@gmail.com [Ceramic Composite Laboratory, Centre for Crystal Growth, SAS, VIT University, Vellore 632014, Tamilnadu (India); Madhuri, W., E-mail: madhuriw12@gmail.com [Ceramic Composite Laboratory, Centre for Crystal Growth, SAS, VIT University, Vellore 632014, Tamilnadu (India); IFW, Leibniz Institute for Solid State and Materials Research, Technische Universität Dresden, 01069 Dresden (Germany)

2017-02-01

Bulk and nano Ni{sub 1-x}Mg{sub x}Fe{sub 2}O{sub 4} (x = 0–1) samples were synthesized via microwave double sintering and microwave assisted hydrothermal techniques respectively. The diffraction pattern confirmed the formation of cubic spinel phases in case of both the ferrites. The larger bulk densities were achieved to the bulk than that of nano. In addition, a comparative study on X-band (8.4–12 GHz) electromagnetic interference shielding properties of current bulk and nanomaterials was elucidated. The results showed that the bulk Ni{sub 0.6}Mg{sub 0.4}Fe{sub 2}O{sub 4} composition revealed the highest total shielding efficiency (SE{sub T}) of ∼17 dB. In comparison, the shielding efficiency values of all bulk contents were higher than that of nano because of larger bulk densities. Moreover, the ac-electromagnetic parameters such as electrical conductivity (σ{sub ac}), the respective real (ε′ & μ′) and imaginary parts (ε″ & μ″) of complex permittivity and permeability were investigated as a function of gigahertz frequency. The bulk ferrites of x = 0.4 & 0.6 showed the high ε″ of 10.26 & 6.71 and μ″ of 3.65 & 3.09 respectively at 12 GHz which can work as promising microwave absorber materials. Interestingly, nanoferrites exhibited negative μ″ values at few frequencies due to geometrical effects which improves the microwave absorption. - Highlights: • Bulk and nano NiMg ferrites are prepared by microwave and hydrothermal method. • X-band EMI shielding properties are studied for both bulk and nano ferrites. • Bulk Ni{sub 0.6}Mg{sub 0.4}Fe{sub 2}O{sub 4} revealed the highest SE{sub T} of ∼17 dB at 8.4 GHz. • Bulk x = 0.4 & 0.6 showed the high ε″ and μ″ at 12 GHz for absorber applications.

Optimization of a solar-blind and middle infrared two-colour photodetector using GaN-based bulk material and quantum wells

International Nuclear Information System (INIS)

Long-Bin, Cen; Bo, Shen; Zhi-Xin, Qin; Guo-Yi, Zhang

2009-01-01

This paper calculates the wavelengths of the interband transitions as a function of the Al mole fraction of A1xGa 1–x N bulk material. It is finds that when the Al mole fraction is between 0.456 and 0.639, the wavelengths correspond to the solar-blind (250 nm to 280 nm). The influence of the structure parameters of A1yGa 1–y N/GaN quantum wells on the wavelength and absorption coefficient of intersubband transitions has been investigated by solving the Schrödinger and Poisson equations self-consistently. The A1 mole fraction of the A1yGa 1–y N barrier changes from 0.30 to 0.46, meanwhile the width of the well changes from 2.9 nm to 2.2 nm, for maximal intersubband absorption in the window of the air (3 μm < λ < 5 μm). The absorption coefficient of the intersubband transition between the ground state and the first excited state decreases with the increase of the wavelength. The results are finally used to discuss the prospects of GaN-based bulk material and quantum wells for a solar-blind and middle infrared two-colour photodetector. (classical areas of phenomenology)

Negative Differential Transconductance in a MoS2 /WSe2 Heterojunction Field Effect Transistor

Science.gov (United States)

Zubair, Ahmad; Nourbakhsh, Amirhasan; Dresselhaus, Mildred; de Gendt, Stefan; Palacios, Tomas

2015-03-01

In this work, we demonstrate the negative transconductance in heterojunction transistors made of two-dimensional materials for the first time. Negative transconductance plays a key role in multi-valued logic/memory and frequency multiplication circuits. The simpler fabrication method of stacked van der Waals heterostructures compared to the conventional bulk semiconductors and large area CVD growth of the layered 2D materials systems makes it a prime candidate for scalable novel applications of their heterostructures. Vertically stacked MoS2/WSe2 heterostructures are fabricated by mechanical exfoliation and an in-house dry transfer process. A two-step process of e-beam lithography and metal deposition (Au on MoS2, and Pd on WSe2) were performed to fabricate n-type MoS2 and ambipolar WSe2 FET. The transfer characteristics on the non-overlapping regions shows the expected characteristics of the n-type, MoS2 FET and ambipolar WSe2 FET. At the same time, the transfer characteristics of the overlapping region between MoS2 and WSe2 show negative differential transconductance. With proper scaling and careful optimization this negative differential transconductance will lead to novel applications.

Randall-Sundrum model with {lambda}<0 and bulk brane viscosity

Energy Technology Data Exchange (ETDEWEB)

Lepe, Samuel [Instituto de Fisica, Pontificia Universidad Catolica de Valparaiso, Casilla 4950, Valparaiso (Chile); Pena, Francisco [Departamento de Ciencias Fisicas, Facultad de Ingenieria, Ciencias y Administracion, Universidad de la Frontera, Avda. Francisco Salazar 01145, Casilla 54-D, Temuco (Chile); Saavedra, Joel [Instituto de Fisica, Pontificia Universidad Catolica de Valparaiso, Casilla 4950, Valparaiso (Chile)], E-mail: joel.saavedra@ucv.cl

2008-04-17

We study the effect of the inclusion of bulk brane viscosity on brane world (BW) cosmology in the framework of the Eckart's theory, we focus in the Randall-Sundrum model with negative tension on the brane.

An overview of rotating machine systems with high-temperature bulk superconductors

Science.gov (United States)

Zhou, Difan; Izumi, Mitsuru; Miki, Motohiro; Felder, Brice; Ida, Tetsuya; Kitano, Masahiro

2012-10-01

The paper contains a review of recent advancements in rotating machines with bulk high-temperature superconductors (HTS). The high critical current density of bulk HTS enables us to design rotating machines with a compact configuration in a practical scheme. The development of an axial-gap-type trapped flux synchronous rotating machine together with the systematic research works at the Tokyo University of Marine Science and Technology since 2001 are briefly introduced. Developments in bulk HTS rotating machines in other research groups are also summarized. The key issues of bulk HTS machines, including material progress of bulk HTS, in situ magnetization, and cooling together with AC loss at low-temperature operation are discussed.

Frontal negativity: An electrophysiological index of interpersonal guilt.

Science.gov (United States)

Leng, Bingbing; Wang, Xiangling; Cao, Bihua; Li, Fuhong

2017-12-01

The present study aimed to reveal the temporal course and electrophysiological correlates of interpersonal guilt. Human participants were asked to perform multiple rounds of a dot-estimation task with their partners, while event-related potential being recorded. The paired participants were informed that they would win money if both responded correctly; otherwise, both of them would lose money. The feeling of guilt in Self-Wrong condition (SW) was significantly higher than that in Both-Wrong and Partner-Wrong conditions. At approximately 350 ms after the onset of feedback presentation, greater negativities were observed in the frontal regions in the guilt condition (i.e., SW) than those in the non-guilt condition. The guilt-modulated frontal negativity might reflect the interactions of self-reflection, condemnation, and negative emotion.

Organic hybrid planar-nanocrystalline bulk heterojunctions

Science.gov (United States)

Forrest, Stephen R [Ann Arbor, MI; Yang, Fan [Piscataway, NJ

2011-03-01

A photosensitive optoelectronic device having an improved hybrid planar bulk heterojunction includes a plurality of photoconductive materials disposed between the anode and the cathode. The photoconductive materials include a first continuous layer of donor material and a second continuous layer of acceptor material. A first network of donor material or materials extends from the first continuous layer toward the second continuous layer, providing continuous pathways for conduction of holes to the first continuous layer. A second network of acceptor material or materials extends from the second continuous layer toward the first continuous layer, providing continuous pathways for conduction of electrons to the second continuous layer. The first network and the second network are interlaced with each other. At least one other photoconductive material is interspersed between the interlaced networks. This other photoconductive material or materials has an absorption spectra different from the donor and acceptor materials.

Tunable multichannel filter in photonic crystal heterostructure containing permeability-negative materials

International Nuclear Information System (INIS)

Hu Xiaoyong; Liu Zheng; Gong Qihuang

2008-01-01

A tunable multichannel filter is demonstrated theoretically based on a one-dimensional photonic crystal heterostructure containing permeability-negative material. The filtering properties of the photonic crystal filter, including the channel number and frequency, can be tuned by adjusting the structure parameters or by a pump laser. The angular response of the photonic crystal filter and the influences of the losses on the filtering properties are also analyzed

Tunable multichannel filter in photonic crystal heterostructure containing permeability-negative materials

Energy Technology Data Exchange (ETDEWEB)

Hu Xiaoyong [State Key Laboratory for Mesoscopic Physics, Department of Physics, Peking University, Beijing 100871 (China)], E-mail: xiaoyonghu@pku.edu.cn; Liu Zheng [State Key Laboratory for Mesoscopic Physics, Department of Physics, Peking University, Beijing 100871 (China); Gong Qihuang [State Key Laboratory for Mesoscopic Physics, Department of Physics, Peking University, Beijing 100871 (China)], E-mail: qhgong@pku.edu.cn

2008-01-14

A tunable multichannel filter is demonstrated theoretically based on a one-dimensional photonic crystal heterostructure containing permeability-negative material. The filtering properties of the photonic crystal filter, including the channel number and frequency, can be tuned by adjusting the structure parameters or by a pump laser. The angular response of the photonic crystal filter and the influences of the losses on the filtering properties are also analyzed.

Bulk microstructure and local elastic properties of carbon nanocomposites studied by impulse acoustic microscopy technique

Science.gov (United States)

Levin, V.; Petronyuk, Yu.; Morokov, E.; Chernozatonskii, L.; Kuzhir, P.; Fierro, V.; Celzard, A.; Bellucci, S.; Bistarelli, S.; Mastrucci, M.; Tabacchioni, I.

2016-05-01

Bulk microstructure and elastic properties of epoxy-nanocarbon nanocomposites for diverse types and different content of carbon nanofiller has been studied by using impulse acoustic microscopy technique. It has been shown occurrence of various types of mesoscopic structure formed by nanoparticles inside the bulk of nanocomposite materials, including nanoparticle conglomerates and nanoparticle aerogel systems. In spite of the bulk microstructure, nanocarbon composites demonstrate elastic uniformity and negligible influence of nanofiller on elastic properties of carbon nanocomposite materials.

Optical and Electrical Characterization of Melt-Grown Bulk Indium Gallium Arsenide and Indium Arsenic Phosphide Alloys

Science.gov (United States)

2011-03-01

spectrum, photoluminescence (PL), and refractive index measurements. Other methods such as infrared imagery and micro probe wavelength dispersing ...States. AFIT/DS/ENP/11-M02 OPTICAL AND ELECTRICAL CHARACTERIZATION OF MELT- GROWN BULK INDIUM GALLIUM ARSENIDE AND INDIUM ARSENIC PHOSPHIDE ...CHARACTERIZATION OF MELT-GROWN BULK INDIUM GALLIUM ARSENIDE AND INDIUM ARSENIC PHOSPHIDE ALLOYS Jean Wei, BS, MS Approved

Broadband one-dimensional photonic crystal wave plate containing single-negative materials.

Science.gov (United States)

Chen, Yihang

2010-09-13

The properties of the phase shift of wave reflected from one-dimensional photonic crystals consisting of periodic layers of single-negative (permittivity- or permeability-negative) materials are demonstrated. As the incident angle increases, the reflection phase shift of TE wave decreases, while that of TM wave increases. The phase shifts of both polarized waves vary smoothly as the frequency changes across the photonic crystal stop band. Consequently, the difference between the phase shift of TE and that of TM wave could remain constant in a rather wide frequency range inside the stop band. These properties are useful to design wave plate or retarder which can be used in wide spectral band. In addition, a broadband photonic crystal quarter-wave plate is proposed.

Preparation and characterization of rare-earth bulks with controllable nanostructures

International Nuclear Information System (INIS)

Song Xiaoyan; Zhang Jiuxing; Li Erdong; Lu Nianduan; Yin Fuxing

2006-01-01

The preparation and characterization of pure rare-earth-metal bulks with controllable nanostructures are reported in this paper. A novel 'oxygen-free' in situ synthesis technique that combines inert-gas condensation with spark plasma sintering (SPS) technology is proposed. Taking into account the special mechanisms of SPS consolidation and the scale effects of nanoparticles, we introduced practical procedures for preparing rare-earth bulks of amorphous, mixed amorphous and nanocrystals, and nanocrystalline microstructures, respectively. Compared with the conventional polycrystalline bulk, these nanostructured bulks exhibit substantially improved physical and mechanical properties. This technique enables comprehensive studies on the microstructures and properties of a large variety of nanostructured metallic materials that are highly reactive in the air

Material recycling of post-consumer polyolefin bulk plastics: Influences on waste sorting and treatment processes in consideration of product qualities achievable.

Science.gov (United States)

Pfeisinger, Christian

2017-02-01

Material recycling of post-consumer bulk plastics made up of polyolefins is well developed. In this article, it is examined which effects on waste sorting and treatment processes influence the qualities of polyolefin-recyclats. It is shown that the properties and their changes during the product life-cycle of a polyolefin are defined by its way of polymerisation, its nature as a thermoplast, additives, other compound and composite materials, but also by the mechanical treatments during the production, its use where contact to foreign materials is possible and the waste sorting and treatment processes. Because of the sum of the effects influencing the quality of polyolefin-recyclats, conclusions are drawn for the material recycling of polyolefins to reach high qualities of their recyclats. Also, legal requirements like the EU regulation 1907/2006 concerning the registration, evaluation, authorisation and restrictions on chemicals are considered.

Modification of Low Refractive Index Polycarbonate for High Refractive Index Applications

Directory of Open Access Journals (Sweden)

Gunjan Suri

2009-01-01

Full Text Available Polycarbonates and polythiourethanes are the most popular materials in use today, for optical applications. Polycarbonates are of two types which fall in the category of low refractive index and medium refractive index. The present paper describes the conversion of low refractive index polycarbonates into high refractive index material by the use of a high refractive index monomer, polythiol, as an additive. Novel polycarbonates, where the properties of refractive index and Abbe number can be tailor made, have been obtained. Thermal studies and refractive index determination indicate the formation of a new polymer with improved properties and suitable for optical applications.

Electrical Double Layer-Induced Ion Surface Accumulation for Ultrasensitive Refractive Index Sensing with Nanostructured Porous Silicon Interferometers.

Science.gov (United States)

Mariani, Stefano; Strambini, Lucanos Marsilio; Barillaro, Giuseppe

2018-03-23

Herein, we provide the first experimental evidence on the use of electrical double layer (EDL)-induced accumulation of charged ions (using both Na + and K + ions in water as the model) onto a negatively charged nanostructured surface (e.g., thermally growth SiO 2 )-Ion Surface Accumulation, ISA-as a means of improving performance of nanostructured porous silicon (PSi) interferometers for optical refractometric applications. Nanostructured PSi interferometers are very promising optical platforms for refractive index sensing due to PSi huge specific surface (hundreds of m 2 per gram) and low preparation cost (less than $0.01 per 8 in. silicon wafer), though they have shown poor resolution ( R) and detection limit (DL) (on the order of 10 -4 -10 -5 RIU) compared to other plasmonic and photonic platforms ( R and DL on the order of 10 -7 -10 -8 RIU). This can be ascribed to both low sensitivity and high noise floor of PSi interferometers when bulk refractive index variation of the solution infiltrating the nanopores either approaches or is below 10 -4 RIU. Electrical double layer-induced ion surface accumulation (EDL-ISA) on oxidized PSi interferometers allows the interferometer output signal (spectral interferogram) to be impressively amplified at bulk refractive index variation below 10 -4 RIU, increasing, in turn, sensitivity up to 2 orders of magnitude and allowing reliable measurement of refractive index variations to be carried out with both DL and R of 10 -7 RIU. This represents a 250-fold-improvement (at least) with respect to the state-of-the-art literature on PSi refractometers and pushes PSi interferometer performance to that of state-of-the-art ultrasensitive photonics/plasmonics refractive index platforms.

High-pressure X-ray diffraction study of bulk- and nanocrystalline GaN

DEFF Research Database (Denmark)

Jorgensen, J.E.; Jakobsen, J.M.; Jiang, Jianzhong

2003-01-01

Bulk- and nanocrystalline GaN have been studied by high-pressure energy-dispersive X-ray diffraction. Pressure-induced structural phase transitions from the wurtzite to the NaCl phase were observed in both materials. The transition pressure was found to be 40 GPa for the bulk-crystalline GaN, while...... the wurtzite phase was retained up to 60 GPa in the case of nanocrystalline GaN. The bulk moduli for the wurtzite phases were determined to be 187 ( 7) and 319 ( 10) GPa for the bulk- and nanocrystalline phases, respectively, while the respective NaCl phases were found to have very similar bulk moduli [ 208...

Natural radioactivity in building materials in the European Union: a database and an estimate of radiological significance.

Science.gov (United States)

Trevisi, R; Risica, S; D'Alessandro, M; Paradiso, D; Nuccetelli, C

2012-02-01

The authors set up a database of activity concentration measurements of natural radionuclides (²²⁶Ra, ²³²Th and ⁴⁰K) in building material. It contains about 10,000 samples of both bulk material (bricks, concrete, cement, natural- and phosphogypsum, sedimentary and igneous bulk stones) and superficial material (igneous and metamorphic stones) used in the construction industry in most European Union Member States. The database allowed the authors to calculate the activity concentration index I--suggested by a European technical guidance document and recently used as a basis for elaborating the draft Euratom Basic Safety Standards Directive--for bricks, concrete and phosphogypsum used in the European Union. Moreover, the percentage could be assessed of materials possibly subject to restrictions, if either of the two dose criteria proposed by the technical guidance were to be adopted. Copyright © 2011 Elsevier Ltd. All rights reserved.

Micromegas in a bulk

International Nuclear Information System (INIS)

Giomataris, I.; De Oliveira, R.; Andriamonje, S.; Aune, S.; Charpak, G.; Colas, P.; Fanourakis, G.; Ferrer, E.; Giganon, A.; Rebourgeard, Ph.; Salin, P.

2006-01-01

In this paper, we present a novel way to manufacture the bulk Micromegas detector. A simple process based on the Printed Circuit Board (PCB) technology is employed to produce the entire sensitive detector. Such a fabrication process could be extended to very large area detectors made by the industry. The low cost fabrication together with the robustness of the electrode materials will make it attractive for several applications ranging from particle physics and astrophysics to medicine

[Recycle of contaminated scrap metal]: Task 1.3.2, Bulk solids feed system. Topical report, October 1993-- January 1996

International Nuclear Information System (INIS)

1996-07-01

A critical requirement in DOE's efforts to recycle, reuse, and dispose of materials from its decontamination and decommissioning activities is the design of a robust system to process a wide variety of bulk solid feeds. The capability to process bulk solids will increase the range of materials and broaden the application of Catalytic Extraction Processing (CEP). The term bulk solids refers to materials that are more economically fed into the top of a molten metal bath than by submerged injection through a tuyere. Molten Metal Technology, Inc. (MMT) has characterized CEP's ability to process bulk solid feed materials and has achieved significant growth in the size of bulk solid particles compatible with Catalytic Extraction Processing. Parametric experimental studies using various feed materials representative of the components of various DOE waste streams have validated design models which establish the reactor operating range as a function of feed material, mass flow rate, and particle size. MMT is investigating the use of a slurry system for bulk solid addition as it is the most efficient means for injecting soils, sludges, and similar physical forms into a catalytic processing unit. MMT is continuing to evaluate condensed phase product removal systems and alternative energy addition sources to enhance the operating efficiency of bulk solids CEP units. A condensed phase product removal system capable of on-demand product removal has been successfully demonstrated. MMT is also investigating the use of a plasma arc torch to provide supplemental heating during bulk solids processing. This comprehensive approach to bulk solids processing is expected to further improve overall process efficiency prior to the deployment of CEP for the recycle, reuse, and disposal of materials from DOE decontamination and decommissioning Activities

Melt-growth bulk superconductors and application to an axial-gap-type rotating machine

International Nuclear Information System (INIS)

Zhang, Yufeng; Zhou, Difan; Ida, Tetsuya; Miki, Motohiro; Izumi, Mitsuru

2016-01-01

The present manuscript addresses key issues in the course of our study of materials processing of bulk high-temperature superconductors, trapped flux and its application to a prototype axial-gap-type rotating machine. The TUMSAT group has conducted a series of studies since 2003 on the growth of GdBa 2 Cu 3 O 7−δ bulk material and its application in a compact low-speed high-torque rotating machine. In the stage of material growth, gaining the advantage of a large motive torque density requires large integrated flux in the motor/generators. A large grain surface might be required with sophisticated techniques for the melt-growth texture in the bulk with optimal flux pinning. In the second stage, the in situ magnetization procedure for bulk superconductors in the applied machine is a crucial part of the technology. Pulsed current excitation by using an armature copper winding has magnetized field pole bulks on the rotor. The axial-gap flux synchronous machine studied in the past decade is a condensed technology and indicates that further scientific development is required for a future compact machine to be superior to conventional ones in accordance with the cryogenic periphery and flux stabilization. (paper)

Spark-plasma-sintering magnetic field assisted compaction of Co{sub 80}Ni{sub 20} nanowires for anisotropic ferromagnetic bulk materials

Energy Technology Data Exchange (ETDEWEB)

Ouar, Nassima; Schoenstein, Frédéric; Mercone, Silvana; Farhat, Samir; Jouini, Noureddine [Laboratoire des Sciences des Procédés et des Matériaux, CNRS, LSPM—UPR 3407, Université Paris 13, Sorbonne-Paris-Cité, 99 Avenue J.-B. Clément, 93430 Villetaneuse (France); Villeroy, Benjamin [Institut de Chimie et des Matériaux Paris Est, CNRS, ICMPE—UMR 7182, Equipe de Chimie Métallurgique des Terres Rares, 2-8 rue Henri Dunant, 94320 Thiais Cedex (France); Leridon, Brigitte [Laboratoire de Physique et d’Étude des Matériaux, LPEM, ESPCI-ParisTech, CNRS, UPMC, 10 rue Vauquelin, F-75231 Paris Cedex 5 (France)

2013-10-28

We developed a two-step process showing the way for sintering anisotropic nanostructured bulk ferromagnetic materials. A new reactor has been optimized allowing the synthesis of several grams per batch of nanopowders via a polyol soft chemistry route. The feasibility of the scale-up has been successfully demonstrated for Co{sub 80}Ni{sub 20} nanowires and a massic yield of ∼97% was obtained. The thus obtained nanowires show an average diameter of ∼6 nm and a length of ∼270 nm. A new bottom-up strategy allowed us to compact the powder into a bulk nanostructured system. We used a spark-plasma-sintering technique under uniaxial compression and low temperature assisted by a permanent magnetic field of 1 T. A macroscopic pellet of partially aligned nanowire arrays has been easily obtained. This showed optimized coercive properties along the direction of the magnetic field applied during compaction (i.e., the nanowires' direction)

Finite element analysis and simulation of rheological properties of bulk molding compound (BMC)

Science.gov (United States)

Ergin, M. Fatih; Aydin, Ismail

2013-12-01

Bulk molding compound (BMC) is one of the important composite materials with various engineering applications. BMC is a thermoset plastic resin blend of various inert fillers, fiber reinforcements, catalysts, stabilizers and pigments that form a viscous, molding compound. Depending on the end-use application, bulk molding compounds are formulated to achieve close dimensional control, flame and scratch resistance, electrical insulation, corrosion and stain resistance, superior mechanical properties, low shrink and color stability. Its excellent flow characteristics, dielectric properties, and flame resistance make this thermoset material well-suited to a wide variety of applications requiring precision in detail and dimensions as well as high performance. When a BMC is used for these purposes, the rheological behavior and properties of the BMC is the main concern. In this paper, finite element analysis of rheological properties of bulk molding composite material was studied. For this purpose, standard samples of composite material were obtained by means of uniaxial hot pressing. 3 point flexural tests were then carried out by using a universal testing machine. Finite element analyses were then performed with defined material properties within a specific constitutive material behavior. Experimental and numerical results were then compared. Good correlation between the numerical simulation and the experimental results was obtained. It was expected with this study that effects of various process parameters and boundary conditions on the rheological behavior of bulk molding compounds could be determined by means of numerical analysis without detailed experimental work.

Gamma index evaluation of IMRT technique using gafchromic film EBT3 for homogeneous and inhomogeneous material

Science.gov (United States)

Nisauf, T. A.; Wibowo, W. E.; Pawiro, S. A.

2017-07-01

This study was done to evaluate the gamma index for registering between the planar of dose planning and the measurement of EBT film. The treatment plan was simulated for 5 patients using Fan Beam Computerized Tomography (FBCT) modality, Philips Pinnacle planning system, 6 MV photon energy, 50 segments IMRT technique, and calculation grid resolution (CGR) of 0.2 cm. Gamma Index (GI) evaluation was done with criteria of dose difference (DD) of 2 %, dose to agreement (DTA) of 2 mm and dose difference (DD) of 5 % DTA of 3 mm, SAD 100 cm, depth of 5 cm and 10 cm of the phantom. The result shows that GI for homogeneous material is greater than for inhomogeneous material with discrepancy to previous work is about 1.98 % for homogeneous material (depth 5 cm) and 2.05 % (depth 10 cm) while it was found of 2.98 % for inhomogeneous material (equivalent depth 5 cm) and 4.59 % (equivalent depth 10 cm).

Reversible bulk-phase change of anthroyl compounds for photopatterning based on photodimerization in the molten state and thermal back reaction.

Science.gov (United States)

Kihara, Hideyuki; Yoshida, Masaru

2013-04-10

As new organic materials for rewritable photopatterning, 2-anthroyl and 9-anthroyl ester compounds were synthesized. Their bulk-phase changes (we use "bulk-phase change" as complete phase change in a mass of a material neither in a surface nor in a small quantity in this study) triggered by photodimerization under melting conditions (melt-photodimerization) and subsequent thermal back reactions were investigated. All the anthroyl compounds exhibited melting points lower than ca. 160 °C, and they were nearly quantitatively converted to the corresponding photodimers by UV irradiation at temperatures of ∼5 °C higher than their respective melting points. We found that there were two kinds of bulk-phase change behaviors through the photoreaction. Two of the anthroyl compounds remained isotropic and lost fluidity during the melt-photodimerization. The obtained photodimers exhibited robust solid-state amorphous phases at room temperature. In contrast, the other three anthroyl compounds showed crystallization during the melt-photodimerization. The resulting photodimers changed from isotropic to crystalline phases, even at high temperature. Various experiments revealed that the bulk phase of the photodimers was affected not by the existence of regioisomers but by their fluidity at the photoirradiation temperature. The latter three photodimers retained enough fluidity, reflecting their high molecular mobilities at the photoirradiation temperature at which the isothermal crystallization occurred. The other two products were not able to crystallize due to low fluidity, resulting in amorphous phases. We also found that all the photodimers reverted to the corresponding monomers by thermal back reaction and recovered their initial photochemical and thermal properties. Using these reversible bulk-phase changes of the anthroyl compounds, we successfully demonstrated rewritable photopatterning in not only negative images but also positive ones, based on the optical contrast

350 keV accelerator based PGNAA setup to detect nitrogen in bulk samples

Energy Technology Data Exchange (ETDEWEB)

Naqvi, A.A., E-mail: aanaqvi@kfupm.edu.sa [Department of Physics and King Fahd University of Petroleum and Minerals, Dhahran (Saudi Arabia); Al-Matouq, Faris A.; Khiari, F.Z.; Gondal, M.A.; Rehman, Khateeb-ur [Department of Physics and King Fahd University of Petroleum and Minerals, Dhahran (Saudi Arabia); Isab, A.A. [Department of Chemistry, King Fahd University of Petroleum and Minerals, Dhahran (Saudi Arabia); Raashid, M.; Dastageer, M.A. [Department of Physics and King Fahd University of Petroleum and Minerals, Dhahran (Saudi Arabia)

2013-11-21

Nitrogen concentration was measured in explosive and narcotics proxy material, e.g. anthranilic acid, caffeine, melamine, and urea samples, bulk samples through thermal neutron capture reaction using 350 keV accelerator based prompt gamma ray neutron activation (PGNAA) setup. Intensity of 2.52, 3.53–3.68, 4.51, 5.27–5.30 and 10.38 MeV prompt gamma rays of nitrogen from the bulk samples was measured using a cylindrical 100 mm×100 mm (diameter×height ) BGO detector. Inspite of interference of nitrogen gamma rays from bulk samples with capture prompt gamma rays from BGO detector material, an excellent agreement between the experimental and calculated yields of nitrogen gamma rays has been obtained. This is an indication of the excellent performance of the PGNAA setup for detection of nitrogen in bulk samples.

350 keV accelerator based PGNAA setup to detect nitrogen in bulk samples

International Nuclear Information System (INIS)

Naqvi, A.A.; Al-Matouq, Faris A.; Khiari, F.Z.; Gondal, M.A.; Rehman, Khateeb-ur; Isab, A.A.; Raashid, M.; Dastageer, M.A.

2013-01-01

Nitrogen concentration was measured in explosive and narcotics proxy material, e.g. anthranilic acid, caffeine, melamine, and urea samples, bulk samples through thermal neutron capture reaction using 350 keV accelerator based prompt gamma ray neutron activation (PGNAA) setup. Intensity of 2.52, 3.53–3.68, 4.51, 5.27–5.30 and 10.38 MeV prompt gamma rays of nitrogen from the bulk samples was measured using a cylindrical 100 mm×100 mm (diameter×height ) BGO detector. Inspite of interference of nitrogen gamma rays from bulk samples with capture prompt gamma rays from BGO detector material, an excellent agreement between the experimental and calculated yields of nitrogen gamma rays has been obtained. This is an indication of the excellent performance of the PGNAA setup for detection of nitrogen in bulk samples

350 keV accelerator based PGNAA setup to detect nitrogen in bulk samples

Science.gov (United States)

Naqvi, A. A.; Al-Matouq, Faris A.; Khiari, F. Z.; Gondal, M. A.; Rehman, Khateeb-ur; Isab, A. A.; Raashid, M.; Dastageer, M. A.

2013-11-01

Nitrogen concentration was measured in explosive and narcotics proxy material, e.g. anthranilic acid, caffeine, melamine, and urea samples, bulk samples through thermal neutron capture reaction using 350 keV accelerator based prompt gamma ray neutron activation (PGNAA) setup. Intensity of 2.52, 3.53-3.68, 4.51, 5.27-5.30 and 10.38 MeV prompt gamma rays of nitrogen from the bulk samples was measured using a cylindrical 100 mm×100 mm (diameter×height ) BGO detector. Inspite of interference of nitrogen gamma rays from bulk samples with capture prompt gamma rays from BGO detector material, an excellent agreement between the experimental and calculated yields of nitrogen gamma rays has been obtained. This is an indication of the excellent performance of the PGNAA setup for detection of nitrogen in bulk samples.

Effect of dual-cure composite resin as restorative material on marginal adaptation of class 2 restorations.

Science.gov (United States)

Bortolotto, Tissiana; Melian, Karla; Krejci, Ivo

2013-10-01

The present study attempted to find a simple direct adhesive restorative technique for the restoration of Class 2 cavities. A self-etch adhesive system with a dual-cured core buildup composite resin (paste 1 + paste 2) was evaluated in its ability to restore proximo-occlusal cavities with margins located on enamel and dentin. The groups were: A, cavity filling (cf) with paste 1 (light-curing component) by using a layering technique; B, cf by mixing both pastes, bulk insertion, and dual curing; and C, cf by mixing both pastes, bulk insertion, and chemical curing. Two control groups (D, negative, bulk; and E, positive, layering technique) were included by restoring cavities with a classic three-step etch-and-rinse adhesive and a universal restorative composite resin. SEM margin analysis was performed before and after thermomechanical loading in a chewing simulator. Percentages (mean ± SD) of "continuous margins" were improved by applying the material in bulk and letting it self cure (54 ± 6) or dual cure (59 ± 9), and no significant differences were observed between these two groups and the positive control (44 ± 19). The present study showed that the dual-cured composite resin tested has the potential to be used as bulk filling material for Class 2 restorations. When used as filling materials, dual-cure composite resins placed in bulk can provide marginal adaptation similar to light-cured composites applied with a complex stratification technique.

Combating wear in bulk solids handling plants

Energy Technology Data Exchange (ETDEWEB)

1986-01-01

A total of five papers presented at a seminar on problems of wear caused by abrasive effects of materials in bulk handling. Topics of papers cover the designer viewpoint, practical experience from the steel, coal, cement and quarry industries to create an awareness of possible solutions.

Using molecular mechanics to predict bulk material properties of fibronectin fibers.

Directory of Open Access Journals (Sweden)

Mark J Bradshaw

Full Text Available The structural proteins of the extracellular matrix (ECM form fibers with finely tuned mechanical properties matched to the time scales of cell traction forces. Several proteins such as fibronectin (Fn and fibrin undergo molecular conformational changes that extend the proteins and are believed to be a major contributor to the extensibility of bulk fibers. The dynamics of these conformational changes have been thoroughly explored since the advent of single molecule force spectroscopy and molecular dynamics simulations but remarkably, these data have not been rigorously applied to the understanding of the time dependent mechanics of bulk ECM fibers. Using measurements of protein density within fibers, we have examined the influence of dynamic molecular conformational changes and the intermolecular arrangement of Fn within fibers on the bulk mechanical properties of Fn fibers. Fibers were simulated as molecular strands with architectures that promote either equal or disparate molecular loading under conditions of constant extension rate. Measurements of protein concentration within micron scale fibers using deep ultraviolet transmission microscopy allowed the simulations to be scaled appropriately for comparison to in vitro measurements of fiber mechanics as well as providing estimates of fiber porosity and water content, suggesting Fn fibers are approximately 75% solute. Comparing the properties predicted by single molecule measurements to in vitro measurements of Fn fibers showed that domain unfolding is sufficient to predict the high extensibility and nonlinear stiffness of Fn fibers with surprising accuracy, with disparately loaded fibers providing the best fit to experiment. This work shows the promise of this microstructural modeling approach for understanding Fn fiber properties, which is generally applicable to other ECM fibers, and could be further expanded to tissue scale by incorporating these simulated fibers into three dimensional

HIPPO, the high-pressure preferred orientation diffractometer at LANSCE for characterization of bulk materials

International Nuclear Information System (INIS)

Bennett, K.; Dreele, R.B. von; Wenk, H.R.

2001-01-01

United States National Laboratory researchers and University of California faculty, representing a broad range of scientific disciplines, is building a novel time-of-flight (TOF) neutron diffractometer and associated in situ equipment at the Manuel Lujan Jr. Neutron Scattering Center (Lujan Center), under the auspices of the United States Department of Energy. The goal with the High-Pressure Preferred Orientation Instrument (HIPPO) is to investigate dynamic processes in heterogeneous bulk materials in a variety of environments. The instrument, which will become available in summer 2001, has the extremely high count-rates necessary to study time-dependent processes in small (1-mm diameter) and large (2-cm diameter) samples, and in a large variety of environmental conditions (10-2000 K cryostats and furnaces, 0-20 GPa pressure vessels, straining cells, goniometers, magnets, etc.). The 3-D arrangement of detectors allows direct measurements of crystal orientation distributions in polycrystalline materials. The analysis of TOF diffraction patterns with versatile Rietveld codes provides simultaneous information on crystal structure, texture, microstructure and phase proportions. While this instrument has many applications in materials science, it is also of great interest for geology and geophysics. Some applications include: kinetics of reactions, structure of silicate glasses and melts, high-pressure investigations of complex systems, evolution of texture and anisotropy during deformation and recrystallization. The Lujan Center aims at creating an instrument with high data through-put and easy access to researchers and students. While the HIPPO instrument will be part of the national user facility operated by the Lujan Center, the scientific program will be guided by the University of California consortium with the goal of satisfying national priorities and establishing an environment of scientific excellence. (author)

HIPPO, the high-pressure preferred orientation diffractometer at LANSCE for characterization of bulk materials

Energy Technology Data Exchange (ETDEWEB)

Bennett, K.; Dreele, R.B. von [Manuel Lujan Jr. Neutron Scattering Center, Los Alamos, NM (United States); Wenk, H.R. [Department of Geology and Geophysics, Univ. of California, Berkely, CA (United States)

2001-03-01

United States National Laboratory researchers and University of California faculty, representing a broad range of scientific disciplines, is building a novel time-of-flight (TOF) neutron diffractometer and associated in situ equipment at the Manuel Lujan Jr. Neutron Scattering Center (Lujan Center), under the auspices of the United States Department of Energy. The goal with the High-Pressure Preferred Orientation Instrument (HIPPO) is to investigate dynamic processes in heterogeneous bulk materials in a variety of environments. The instrument, which will become available in summer 2001, has the extremely high count-rates necessary to study time-dependent processes in small (1-mm diameter) and large (2-cm diameter) samples, and in a large variety of environmental conditions (10-2000 K cryostats and furnaces, 0-20 GPa pressure vessels, straining cells, goniometers, magnets, etc.). The 3-D arrangement of detectors allows direct measurements of crystal orientation distributions in polycrystalline materials. The analysis of TOF diffraction patterns with versatile Rietveld codes provides simultaneous information on crystal structure, texture, microstructure and phase proportions. While this instrument has many applications in materials science, it is also of great interest for geology and geophysics. Some applications include: kinetics of reactions, structure of silicate glasses and melts, high-pressure investigations of complex systems, evolution of texture and anisotropy during deformation and recrystallization. The Lujan Center aims at creating an instrument with high data through-put and easy access to researchers and students. While the HIPPO instrument will be part of the national user facility operated by the Lujan Center, the scientific program will be guided by the University of California consortium with the goal of satisfying national priorities and establishing an environment of scientific excellence. (author)

Evaluation and remediation of bulk soap dispensers for biofilm.

Science.gov (United States)

Lorenz, Lindsey A; Ramsay, Bradley D; Goeres, Darla M; Fields, Matthew W; Zapka, Carrie A; Macinga, David R

2012-01-01

Recent studies evaluating bulk soap in public restroom soap dispensers have demonstrated up to 25% of open refillable bulk-soap dispensers were contaminated with ~ 6 log(10)(CFU ml(-1)) heterotrophic bacteria. In this study, plastic counter-mounted, plastic wall-mounted and stainless steel wall-mounted dispensers were analyzed for suspended and biofilm bacteria using total cell and viable plate counts. Independent of dispenser type or construction material, the bulk soap was contaminated with 4-7 log(10)(CFU ml(-1)) bacteria, while 4-6 log(10)(CFU cm(-2)) biofilm bacteria were isolated from the inside surfaces of the dispensers (n = 6). Dispenser remediation studies, including a 10 min soak with 5000 mg l(-1) sodium hypochlorite, were then conducted to determine the efficacy of cleaning and disinfectant procedures against established biofilms. The testing showed that contamination of the bulk soap returned to pre-test levels within 7-14 days. These results demonstrate biofilm is present in contaminated bulk-soap dispensers and remediation studies to clean and sanitize the dispensers are temporary.

Left Handed Materials: A New Paradigm in Structured Electromagnetics

International Nuclear Information System (INIS)

Johri, Manoj; Paudyal, Harihar

2010-05-01

A new paradigm has emerged exhibiting reverse electromagnetic properties. Novel composite and micro-structured materials (metamaterials) have been designed to control electromagnetic radiation. Such substances have been called as Left Handed Material (LHM) with simultaneous negative permittivity and negative permeability and negative refractive index as well. Left handed materials are of importance because of their ability to influence the behavior of electromagnetic radiation and to display properties beyond those available in naturally occurring materials. Typically these are sub-wavelength artificial structures where the dimensions are very small compared to the working wavelength. These dimensions are normally of the order of λ/10 where λ is the wavelength of electromagnetic wave propagating in the material. Emergence of this new paradigm leads to some very interesting consequences, such as, to create lenses that are not diffraction limited, cloaking, sensors (chemical, biological and individual molecule), optical and radio communication. This new development in structured electromagnetic materials has had a dramatic impact on the physics, optics and engineering communities. (author)

Bulk metallic glass for low noise fluxgate, Phase I

Data.gov (United States)

National Aeronautics and Space Administration — The team of Prime Photonics, Virginia Tech, and Utron Kinetics propose to demonstrate a method for fabrication of a bulk, amorphous, cobalt-rich material that...

Influence of the power law index on the fiber breakage during injection molding by numerical simulations

Science.gov (United States)

Desplentere, Frederik; Six, Wim; Bonte, Hilde; Debrabandere, Eric

2013-04-01

In predictive engineering for polymer processes, the proper prediction of material microstructure from known processing conditions and constituent material properties is a critical step forward properly predicting bulk properties in the finished composite. Operating within the context of long-fiber thermoplastics (LFT, length > 15mm) this investigation concentrates on the influence of the power law index on the final fiber length distribution within the injection molded part. To realize this, the Autodesk Simulation Moldflow Insight Scandium 2013 software has been used. In this software, a fiber breakage algorithm is available from this release on. Using virtual material data with realistic viscosity levels allows to separate the influence of the power law index on the fiber breakage from the other material and process parameters. Applying standard settings for the fiber breakage parameters results in an obvious influence on the fiber length distribution through the thickness of the part and also as function of position in the part. Finally, the influence of the shear rate constant within the fiber breakage model has been investigated illustrating the possibility to fit the virtual fiber length distribution to the possible experimentally available data.

New infrared transmitting material via inverse vulcanization of elemental sulfur to prepare high refractive index polymers.

Science.gov (United States)

Griebel, Jared J; Namnabat, Soha; Kim, Eui Tae; Himmelhuber, Roland; Moronta, Dominic H; Chung, Woo Jin; Simmonds, Adam G; Kim, Kyung-Jo; van der Laan, John; Nguyen, Ngoc A; Dereniak, Eustace L; Mackay, Michael E; Char, Kookheon; Glass, Richard S; Norwood, Robert A; Pyun, Jeffrey

2014-05-21

Polymers for IR imaging: The preparation of high refractive index polymers (n = 1.75 to 1.86) via the inverse vulcanization of elemental sulfur is reported. High quality imaging in the near (1.5 μm) and mid-IR (3-5 μm) regions using high refractive index polymeric lenses from these sulfur materials was demonstrated. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Bulk Crystal Growth, and High-Resolution X-ray Diffraction Results of LiZnAs Semiconductor Material

Science.gov (United States)

Montag, Benjamin W.; Reichenberger, Michael A.; Sunder, Madhana; Ugorowski, Philip B.; Nelson, Kyle A.; Henson, Luke C.; McGregor, Douglas S.

2017-08-01

LiZnAs is being explored as a candidate for solid-state neutron detectors. The compact form, solid-state device would have greater efficiency than present day gas-filled 3He and 10BF3 detectors. Devices fabricated from LiZnAs having either natural Li (nominally 7.5% 6Li) or enriched 6Li (usually 95% 6Li) as constituent atoms may provide a material for compact high efficiency neutron detectors. The 6Li( n, t)4He reaction yields a total Q-value of 4.78 MeV, an energy larger than that of the 10B reaction, which can easily be identified above background radiations. LiZnAs material was synthesized by preparing equimolar portions of Li, Zn, and As sealed under vacuum (10-6 Torr) in quartz ampoules lined with boron nitride and subsequently reacted in a compounding furnace (Montag et al. in J Cryst Growth 412:103, 2015). The raw synthesized LiZnAs was purified by a static vacuum sublimation in quartz (Montag et al. in J Cryst Growth 438:99, 2016). Bulk crystalline LiZnAs ingots were grown from the purified material with a high-temperature Bridgman-style growth process described here. One of the largest LiZnAs ingots harvested was 9.6 mm in diameter and 4.2 mm in length. Samples were harvested from the ingot and were characterized for crystallinity using a Bruker AXS Inc. D8 AXS Inc. D2 CRYSO, energy dispersive x-ray diffractometer, and a Bruker AXS Inc. D8 DISCOVER, high-resolution x-ray diffractometer equipped with molybdenum radiation, Gobel mirror, four bounce germanium monochromator and a scintillation detector. The primary beam divergence was determined to be 0.004°, using a single crystal Si standard. The x-ray based characterization revealed that the samples nucleated in the (110) direction and a high-resolution open detector rocking curve recorded on the (220) LiZnAs yielded a full width at half maximum (FWHM) of 0.235°. Sectional pole figures using off-axis reflections of the (211) LiZnAs confirmed in-plane ordering, and also indicated the presence of multiple

Modelling of the Flow of Streams of Cohesionless and Cohesive Bulk Materials in a Conveyor Discharge Point with a Flat Conveyor Belt

Science.gov (United States)

Cyganiuk, J. A.; Kuryło, P.

2018-02-01

The paper presents the analysis of flow conditions of cohesive and cohesionless bulk materials in a conveyor discharge point of a flat conveyor belt. The analysis was carried out for stationary flows at high velocities. It presents mathematical methods for the description of the velocity of a material leaving a throwing point of a flat conveyor belt as well as final equations which enable the determination of velocity of the material after it has left the throwing point (with the accuracy sufficient for practical use). Next, the velocity calculated for the proposed mathematical description (for selected material groups) has been compared with the velocity obtained from mathematical relations commonly used by engineers. The proposed equations for determining the velocity of the material beyond the point have proved useful, since they enable excluding the indirect equations. Finally, the difference between the values of the velocity obtained with the proposed and indirect equations have been determined and the relative error for the proposed method has been calculated.

Indirect effect of financial strain on daily cortisol output through daily negative to positive affect index in the Coronary Artery Risk Development in Young Adults Study.

Science.gov (United States)

Puterman, Eli; Haritatos, Jana; Adler, Nancy E; Sidney, Steve; Schwartz, Joseph E; Epel, Elissa S

2013-12-01

Daily affect is important to health and has been linked to cortisol. The combination of high negative affect and low positive affect may have a bigger impact on increasing HPA axis activity than either positive or negative affect alone. Financial strain may both dampen positive affect as well as increase negative affect, and thus provides an excellent context for understanding the associations between daily affect and cortisol. Using random effects mixed modeling with maximum likelihood estimation, we examined the relationship between self-reported financial strain and estimated mean daily cortisol level (latent cortisol variable), based on six salivary cortisol assessments throughout the day, and whether this relationship was mediated by greater daily negative to positive affect index measured concurrently in a sample of 776 Coronary Artery Risk Development in Young Adults (CARDIA) Study participants. The analysis revealed that while no total direct effect existed for financial strain on cortisol, there was a significant indirect effect of high negative affect to low positive affect, linking financial strain to elevated cortisol. In this sample, the effects of financial strain on cortisol through either positive affect or negative affect alone were not significant. A combined affect index may be a more sensitive and powerful measure than either negative or positive affect alone, tapping the burden of chronic financial strain, and its effects on biology. Copyright © 2013 Elsevier Ltd. All rights reserved.

Negative thermal expansion in functional materials: controllable thermal expansion by chemical modifications.

Science.gov (United States)

Chen, Jun; Hu, Lei; Deng, Jinxia; Xing, Xianran

2015-06-07

Negative thermal expansion (NTE) is an intriguing physical property of solids, which is a consequence of a complex interplay among the lattice, phonons, and electrons. Interestingly, a large number of NTE materials have been found in various types of functional materials. In the last two decades good progress has been achieved to discover new phenomena and mechanisms of NTE. In the present review article, NTE is reviewed in functional materials of ferroelectrics, magnetics, multiferroics, superconductors, temperature-induced electron configuration change and so on. Zero thermal expansion (ZTE) of functional materials is emphasized due to the importance for practical applications. The NTE functional materials present a general physical picture to reveal a strong coupling role between physical properties and NTE. There is a general nature of NTE for both ferroelectrics and magnetics, in which NTE is determined by either ferroelectric order or magnetic one. In NTE functional materials, a multi-way to control thermal expansion can be established through the coupling roles of ferroelectricity-NTE, magnetism-NTE, change of electron configuration-NTE, open-framework-NTE, and so on. Chemical modification has been proved to be an effective method to control thermal expansion. Finally, challenges and questions are discussed for the development of NTE materials. There remains a challenge to discover a "perfect" NTE material for each specific application for chemists. The future studies on NTE functional materials will definitely promote the development of NTE materials.

A new material platform of Si photonics for implementing architecture of dense wavelength division multiplexing on Si bulk wafer

Science.gov (United States)

Zhang, Ziyi; Yako, Motoki; Ju, Kan; Kawai, Naoyuki; Chaisakul, Papichaya; Tsuchizawa, Tai; Hikita, Makoto; Yamada, Koji; Ishikawa, Yasuhiko; Wada, Kazumi

2017-12-01

A new materials group to implement dense wavelength division multiplexing (DWDM) in Si photonics is proposed. A large thermo-optic (TO) coefficient of Si malfunctions multiplexer/demultiplexer (MUX/DEMUX) on a chip under thermal fluctuation, and thus DWDM implementation, has been one of the most challenging targets in Si photonics. The present study specifies an optical materials group for DWDM by a systematic survey of their TO coefficients and refractive indices. The group is classified as mid-index contrast optics (MiDex) materials, and non-stoichiometric silicon nitride (SiNx) is chosen to demonstrate its significant thermal stability. The TO coefficient of non-stoichiometric SiNx is precisely measured in the temperature range 24-76 °C using the SiNx rings prepared by two methods: chemical vapor deposition (CVD) and physical vapor deposition (PVD). The CVD-SiNx ring reveals nearly the same TO coefficient reported for stoichiometric CVD-Si3N4, while the value for the PVD-SiNx ring is slightly higher. Both SiNx rings lock their resonance frequencies within 100 GHz in this temperature range. Since CVD-SiNx needs a high temperature annealing to reduce N-H bond absorption, it is concluded that PVD-SiNx is suited as a MiDex material introduced in the CMOS back-end-of-line. Further stabilization is required, considering the crosstalk between two channels; a 'silicone' polymer is employed to compensate for the temperature fluctuation using its negative TO coefficient, called athermalization. This demonstrates that the resonance of these SiNx rings is locked within 50 GHz at the same temperature range in the wavelength range 1460-1620 nm (the so-called S, C, and L bands in optical fiber communication networks). A further survey on the MiDex materials strongly suggests that Al2O3, Ga2O3 Ta2O5, HfO2 and their alloys should provide even more stable platforms for DWDM implementation in MiDex photonics. It is discussed that the MiDex photonics will find various applications

A new material platform of Si photonics for implementing architecture of dense wavelength division multiplexing on Si bulk wafer.

Science.gov (United States)

Zhang, Ziyi; Yako, Motoki; Ju, Kan; Kawai, Naoyuki; Chaisakul, Papichaya; Tsuchizawa, Tai; Hikita, Makoto; Yamada, Koji; Ishikawa, Yasuhiko; Wada, Kazumi

2017-01-01

A new materials group to implement dense wavelength division multiplexing (DWDM) in Si photonics is proposed. A large thermo-optic (TO) coefficient of Si malfunctions multiplexer/demultiplexer (MUX/DEMUX) on a chip under thermal fluctuation, and thus DWDM implementation, has been one of the most challenging targets in Si photonics. The present study specifies an optical materials group for DWDM by a systematic survey of their TO coefficients and refractive indices. The group is classified as mid-index contrast optics (MiDex) materials, and non-stoichiometric silicon nitride (SiN x ) is chosen to demonstrate its significant thermal stability. The TO coefficient of non-stoichiometric SiN x is precisely measured in the temperature range 24-76 °C using the SiN x rings prepared by two methods: chemical vapor deposition (CVD) and physical vapor deposition (PVD). The CVD-SiN x ring reveals nearly the same TO coefficient reported for stoichiometric CVD-Si 3 N 4 , while the value for the PVD-SiN x ring is slightly higher. Both SiN x rings lock their resonance frequencies within 100 GHz in this temperature range. Since CVD-SiN x needs a high temperature annealing to reduce N-H bond absorption, it is concluded that PVD-SiN x is suited as a MiDex material introduced in the CMOS back-end-of-line. Further stabilization is required, considering the crosstalk between two channels; a 'silicone' polymer is employed to compensate for the temperature fluctuation using its negative TO coefficient, called athermalization. This demonstrates that the resonance of these SiN x rings is locked within 50 GHz at the same temperature range in the wavelength range 1460-1620 nm (the so-called S, C, and L bands in optical fiber communication networks). A further survey on the MiDex materials strongly suggests that Al 2 O 3 , Ga 2 O 3 Ta 2 O 5 , HfO 2 and their alloys should provide even more stable platforms for DWDM implementation in MiDex photonics. It is discussed that the MiDex photonics

Laser-induced damage of materials in bulk, thin-film, and liquid forms

International Nuclear Information System (INIS)

Natoli, Jean-Yves; Gallais, Laurent; Akhouayri, Hassan; Amra, Claude

2002-01-01

Accurate threshold curves of laser-induced damage (7-ns single shot at 1.064 μm) are measured in bulk and at the surfaces of optical components such as substrates, thin films, multilayers, and liquids. The shapes and the slopes of the curves are related to the spot size and to the densities of the nanodefects that are responsible for damage. First, these densities are reported for bulk substrates. In surfaces and films the recorded extrinsic and intrinsic threshold curves permit the discrimination of the effects of microdefects and nanodefects. In all cases the density of nanocenters is extracted by means of a phenomenological approach. Then we test liquids and mixtures of liquids with controlled defect densities. The results emphasize the agreement between measurement and prediction and demonstrate the validity of the presence of different kinds of nanocenter as the precursors of laser damage

Comparisons of Soil Properties, Enzyme Activities and Microbial Communities in Heavy Metal Contaminated Bulk and Rhizosphere Soils of Robinia pseudoacacia L. in the Northern Foot of Qinling Mountain

Directory of Open Access Journals (Sweden)

Yurong Yang

2017-11-01

Full Text Available The toxic effects of heavy metal (HM contamination on plant metabolism and soil microorganisms have been emphasized recently; however, little is known about the differences in soil physical, chemical, and biological properties between bulk and rhizosphere soils contaminated with HMs in forest ecosystem. The present study was conducted to evaluate the rhizosphere effect on soil properties, enzyme activities and bacterial communities associated with Robinia pseudoacacia L. along a HM contamination gradient. Soil organic matter (SOM, available nitrogen (AN and phosphorus (AP contents were significantly higher in rhizosphere soil than those in bulk soil at HM contaminated sites (p < 0.05. Compared to bulk soil, activities of four soil enzymes indicative of C cycle (β-glucosidase, N cycle (protease, urease and P cycle (alkaline phosphatase in rhizosphere soil across all study sites increased by 47.5%, 64.1%, 52.9% and 103.8%, respectively. Quantitative PCR (qPCR and restriction fragment length polymorphism (RFLP were used to determine the relative abundance, composition and diversity of bacteria in both bulk and rhizosphere soils, respectively. The copy number of bacterial 16S rRNA gene in bulk soil was significantly lower than that in rhizosphere soil (p < 0.05, and it had significantly negative correlations with total/DTPA-extractable Pb concentrations (p < 0.01. Alphaproteobacteria, Gammaproteobacteria and Firmicutes were the most dominant groups of bacteria at different study sites. The bacterial diversity index of Species richness (S and Margalef (dMa were significantly higher in rhizosphere soil compared with those in bulk soil, although no difference could be found in Simpson index (D between bulk and rhizosphere soils (p > 0.05. Redundancy analysis (RDA results showed that soil pH, EC, SOM and total/DTPA-extractable Pb concentrations were the most important variables affecting relative abundance, composition and diversity of bacteria (p < 0

Solar, interplanetary and terrestrial features associated with periods of prolonged positive and negative Dst index

International Nuclear Information System (INIS)

Rajaram, G.

1989-01-01

From a survey of the published final values of the geomagnetic index D st for the period 1958-1972, we found long time intervals of over 25-30 days, during which this index remained consistently positive (D st +) or negative (D st -). A study is made of relevant parameters on the ground, in the magnetosphere, in the solar wind and on the Sun to seek out systematic features associated with the two conditions. In order to eliminate factors arising from seasonal and solar cycle variations, we selected pairs of D st + and D st - which involve successive months of the same year, or the same month of two successive years. Three parameters which show a systematic difference between D st + and D st - intervals are found to be 1) the state of solar photospheric magnetic fields 2) the flux density of solar MeV protons measured in the magnetosphere and 3) the southward component of the interplanetary magnetic field. While the effect of the last on geomagnetic activity has been well-discussed in the literature, it is suggested that the correlations of the first two to the conditions of D st + and D st - demand a careful scrutiny of the solar-terrestrial relationship. (author)

Nonlinear refractive index measurements and self-action effects in Roselle-Hibiscus Sabdariffa solutions

Science.gov (United States)

Henari, F. Z.; Al-Saie, A.

2006-12-01

We report the observation of self-action phenomena, such as self-focusing, self-defocusing, self-phase modulation and beam fanning in Roselle-Hibiscus Sabdariffa solutions. This material is found to be a new type of natural nonlinear media, and the nonlinear reflective index coefficient has been determined using a Z-scan technique and by measuring the critical power for the self-trapping effect. Z-scan measurements show that this material has a large negative nonlinear refractive index, n 2 = 1 × 10-4 esu. A comparison between the experimental n 2 values and the calculated thermal value for n 2 suggests that the major contribution to nonlinear response is of thermal origin.

Free standing bulk metallic glass microcomponents: Tooling considerations

DEFF Research Database (Denmark)

Byrne, Cormac; Eldrup, Morten Mostgaard; Ohnuma, Masato

2010-01-01

Bulk metallic glasses have enormous potential for use in small-scale devices such as MEMS and biomedical components. Thermoplastic forging of free standing components poses challenges unlike those seen when forging crystalline materials. Central to these challenges is the simultaneous advantage/disadvantage...

Focusing light in a bianisotropic slab with negatively refracting materials

International Nuclear Information System (INIS)

Liu Yan; Guenneau, Sebastien; Gralak, Boris; Ramakrishna, S Anantha

2013-01-01

We investigate the electromagnetic response of a pair of complementary bianisotropic media, which consist of a medium with positive refractive index (+ε, +μ, +ξ) and a medium with negative refractive index(−ε, −μ, −ξ). We show that this idealized system has peculiar imaging properties in that it reproduces images of a source, in principle, with unlimited resolution. We then consider an infinite array of line sources regularly spaced in a 1D photonic crystal (PC) consisting of 2n layers of bianisotropic complementary media. Using coordinate transformations, we map this system into 2D corner chiral lenses of 2n heterogeneous anisotropic complementary media sharing a vertex, within which light circles around closed trajectories. Alternatively, one can consider corner lenses with homogeneous isotropic media and map them into 1D PCs with heterogeneous bianisotropic layers. Interestingly, such complementary media are described by scalar, or matrix valued, sign-shifting parameters, which satisfy a new version of the generalized lens theorem of Pendry and Ramakrishna. This theorem can be derived using Fourier series solutions of the Maxwell–Tellegen equations, or from space–time symmetry arguments. Also of interest are 2D periodic checkerboards consisting of alternating rectangular cells of complementary media which are such that one point source in one cell gives rise to an infinite set of images with an image in every other cell. Such checkerboards can themselves be mapped into a class of 3D corner lenses of complementary bianisotropic media. These theoretical results are illustrated by finite element computations. (paper)

Materials process and applications of single grain (RE)-Ba-Cu-O bulk high-temperature superconductors

Energy Technology Data Exchange (ETDEWEB)

Li Beizhan; Zhou Difan; Xu Kun; Hara, Shogo; Tsuzuki, Keita; Miki, Motohiro; Felder, Brice; Deng Zigang [Laboratory of Applied Physics, Department of Marine Electronics and Mechanical Engineering, Tokyo University of Marine Science and Technology (TUMSAT), 2-1-6, Etchu-jima, Koto-ku, Tokyo 135-8533 (Japan); Izumi, Mitsuru, E-mail: izumi@kaiyodai.ac.jp [Laboratory of Applied Physics, Department of Marine Electronics and Mechanical Engineering, Tokyo University of Marine Science and Technology (TUMSAT), 2-1-6, Etchu-jima, Koto-ku, Tokyo 135-8533 (Japan)

2012-11-20

This paper reviews recent advances in the melt process of (RE)-Ba-Cu-O [(RE)BCO, where RE represents a rare earth element] single grain high-temperature superconductors (HTSs), bulks and its applications. The efforts on the improvement of the magnetic flux pinning with employing the top-seeded melt-growth process technique and using a seeded infiltration and growth process are discussed. Which including various chemical doping strategies and controlled pushing effect based on the peritectic reaction of (RE)BCO. The typical experiment results, such as the largest single domain bulk, the clear TEM observations and the significant critical current density, are summarized together with the magnetization techniques. Finally, we highlight the recent prominent progress of HTS bulk applications, including Maglev, flywheel, power device, magnetic drug delivery system and magnetic resonance devices.

Materials process and applications of single grain (RE)-Ba-Cu-O bulk high-temperature superconductors

Science.gov (United States)

Li, Beizhan; Zhou, Difan; Xu, Kun; Hara, Shogo; Tsuzuki, Keita; Miki, Motohiro; Felder, Brice; Deng, Zigang; Izumi, Mitsuru

2012-11-01

This paper reviews recent advances in the melt process of (RE)-Ba-Cu-O [(RE)BCO, where RE represents a rare earth element] single grain high-temperature superconductors (HTSs), bulks and its applications. The efforts on the improvement of the magnetic flux pinning with employing the top-seeded melt-growth process technique and using a seeded infiltration and growth process are discussed. Which including various chemical doping strategies and controlled pushing effect based on the peritectic reaction of (RE)BCO. The typical experiment results, such as the largest single domain bulk, the clear TEM observations and the significant critical current density, are summarized together with the magnetization techniques. Finally, we highlight the recent prominent progress of HTS bulk applications, including Maglev, flywheel, power device, magnetic drug delivery system and magnetic resonance devices.

Surface-spin magnetism of antiferromagnetic NiO in nanoparticle and bulk morphology

International Nuclear Information System (INIS)

Jagodic, M; Jaglicic, Z; Jelen, A; Dolinsek, J; Lee, Jin Bae; Kim, Hae Jin; Kim, Young-Min

2009-01-01

The surface-spin magnetism of the antiferromagnetic (AFM) material NiO in nanoparticle and bulk morphology was investigated by magnetic measurements (temperature-dependent zero-field-cooled (zfc) and field-cooled (fc) dc susceptibility, ac susceptibility and zfc and fc hysteresis loops). We addressed the question of whether the multisublattice ordering of the uncompensated surface spins and the exchange bias (EB) effect are only present in the nanoparticles, originating from their high surface-to-volume ratio or if these surface phenomena are generally present in the AFM materials regardless of their bulky or nanoparticle morphology, but the effect is just too small to be detected experimentally in the bulk due to a very small surface magnetization. Performing experiments on the NiO nanoparticles of different sizes and bulk NiO grains, we show that coercivity enhancement and hysteresis loop shift in the fc experiments, considered to be the key experimental manifestations of multisublattice ordering and the EB effect, are true nanoscale phenomena only present in the nanoparticles and absent in the bulk.

Rat animal model for preclinical testing of microparticle urethral bulking agents.

Science.gov (United States)

Mann-Gow, Travis K; Blaivas, Jerry G; King, Benjamin J; El-Ghannam, Ahmed; Knabe, Christine; Lam, Michael K; Kida, Masatoshi; Sikavi, Cameron S; Plante, Mark K; Krhut, Jan; Zvara, Peter

2015-04-01

To develop an economic, practical and readily available animal model for preclinical testing of urethral bulking therapies, as well as to establish feasible experimental methods that allow for complete analysis of hard microparticle bulking agents. Alumina ceramic beads suspended in hyaluronic acid were injected into the proximal urethra of 15 female rats under an operating microscope. We assessed overall lower urinary tract function, bulking material intraurethral integrity and local host tissue response over time. Microphotographs were taken during injection and again 6 months postoperatively, before urethral harvest. Urinary flow rate and voiding frequency were assessed before and after injection. At 6 months, the urethra was removed and embedded in resin. Hard tissue sections were cut using a sawing microtome, and processed for histological analysis using scanning electron microscopy, light microscopy and immunohistochemistry. Microphotographs of the urethra showed complete volume retention of the bulking agent at 6 months. There was no significant difference between average urinary frequency and mean urinary flow rate at 1 and 3 months postinjection as compared with baseline. Scanning electron microscopy proved suitable for evaluation of microparticle size and integrity, as well as local tissue remodeling. Light microscopy and immunohistochemistry allowed for evaluation of an inflammatory host tissue reaction to the bulking agent. The microsurgical injection technique, in vivo physiology and novel hard tissue processing for histology, described in the present study, will allow for future comprehensive preclinical testing of urethral bulking therapy agents containing microparticles made of a hard material. © 2015 The Japanese Urological Association.

Nanoindentation creep versus bulk compressive creep of dental resin-composites.

Science.gov (United States)

El-Safty, S; Silikas, N; Akhtar, R; Watts, D C

2012-11-01

To evaluate nanoindentation as an experimental tool for characterizing the viscoelastic time-dependent creep of resin-composites and to compare the resulting parameters with those obtained by bulk compressive creep. Ten dental resin-composites: five conventional, three bulk-fill and two flowable were investigated using both nanoindentation creep and bulk compressive creep methods. For nano creep, disc specimens (15mm×2mm) were prepared from each material by first injecting the resin-composite paste into metallic molds. Specimens were irradiated from top and bottom surfaces in multiple overlapping points to ensure optimal polymerization using a visible light curing unit with output irradiance of 650mW/cm(2). Specimens then were mounted in 3cm diameter phenolic ring forms and embedded in a self-curing polystyrene resin. Following grinding and polishing, specimens were stored in distilled water at 37°C for 24h. Using an Agilent Technologies XP nanoindenter equipped with a Berkovich diamond tip (100nm radius), the nano creep was measured at a maximum load of 10mN and the creep recovery was determined when each specimen was unloaded to 1mN. For bulk compressive creep, stainless steel split molds (4mm×6mm) were used to prepare cylindrical specimens which were thoroughly irradiated at 650mW/cm(2) from multiple directions and stored in distilled water at 37°C for 24h. Specimens were loaded (20MPa) for 2h and unloaded for 2h. One-way ANOVA, Levene's test for homogeneity of variance and the Bonferroni post hoc test (all at p≤0.05), plus regression plots, were used for statistical analysis. Dependent on the type of resin-composite material and the loading/unloading parameters, nanoindentation creep ranged from 29.58nm to 90.99nm and permanent set ranged from 8.96nm to 30.65nm. Bulk compressive creep ranged from 0.47% to 1.24% and permanent set ranged from 0.09% to 0.38%. There was a significant (p=0.001) strong positive non-linear correlation (r(2)=0.97) between bulk

Scaling laws in high-energy inverse compton scattering. II. Effect of bulk motions

International Nuclear Information System (INIS)

Nozawa, Satoshi; Kohyama, Yasuharu; Itoh, Naoki

2010-01-01

We study the inverse Compton scattering of the CMB photons off high-energy nonthermal electrons. We extend the formalism obtained by the previous paper to the case where the electrons have nonzero bulk motions with respect to the CMB frame. Assuming the power-law electron distribution, we find the same scaling law for the probability distribution function P 1,K (s) as P 1 (s) which corresponds to the zero bulk motions, where the peak height and peak position depend only on the power-index parameter. We solved the rate equation analytically. It is found that the spectral intensity function also has the same scaling law. The effect of the bulk motions to the spectral intensity function is found to be small. The present study will be applicable to the analysis of the x-ray and gamma-ray emission models from various astrophysical objects with nonzero bulk motions such as radio galaxies and astrophysical jets.

Enhanced bulk heterojunction devices prepared by thermal and solvent vapor annealing processes

Science.gov (United States)

Forrest, Stephen R.; Thompson, Mark E.; Wei, Guodan; Wang, Siyi

2017-09-19

A method of preparing a bulk heterojunction organic photovoltaic cell through combinations of thermal and solvent vapor annealing are described. Bulk heterojunction films may prepared by known methods such as spin coating, and then exposed to one or more vaporized solvents and thermally annealed in an effort to enhance the crystalline nature of the photoactive materials.

Millimeter wave surface resistance of grain-aligned Y1Ba2Cu3Ox bulk material

International Nuclear Information System (INIS)

Wosik, J.; Kranenburg, R.A.; Wolfe, J.C.; Selvamanickam, V.; Salama, K.

1991-01-01

We report measurements of the millimeter wave surface resistance of grain-aligned YBa 2 Cu 3 O x bulk material grown by a liquid phase process. The measurements were performed by replacing the endplate of a TE 011 cylindrical copper cavity with the superconducting sample. Surface resistance was measured for samples with surfaces oriented perpendicular and parallel to the c-axis of the grains. We show that, for the parallel configuration, the surface resistance at 77 K and 80 GHz is typically near 100 mΩ. For a very well-aligned sample with a very low density of Y 2 BaCuO y precipitates, measured in the perpendicular configuration, the transition width (10%--90%) is about 2 K and the surface resistance is less than 50 mΩ at 88 K. The effect of microstructure on surface resistance is discussed

Different types of pre-lithiated hard carbon as negative electrode material for lithium-ion capacitors

International Nuclear Information System (INIS)

Zhang, Jin; Liu, Xifeng; Wang, Jing; Shi, Jingli; Shi, Zhiqiang

2016-01-01

Highlights: • Two types of HC materials with different properties as negative electrode. • Lithium ion intercalation plateau of HC affects electrochemical performance of LIC. • The electrochemical performance of LIC is operated at different potential ranges. • The selection of HC and appropriate potential range of LIC have been proposed. - ABSTRACT: Lithium-ion capacitors (LICs) are assembled with activated carbon (AC) cathode and pre-lithiated hard carbon (HC) anode. Two kinds of HC materials with different physical and electrochemical behaviors have been investigated as the negative electrodes for LIC. Compared with spherical HC, the irregular HC shows a distinct lithium ion intercalation plateau in the charge–discharge process. The existence of lithium ion intercalation plateau for irregular HC greatly affects the electrochemical behavior of HC negative electrode and AC positive electrode. The effect of working potential range on the electrochemical performance of LIC-SH and LIC-IH is investigated by the galvanostatic charging–discharging, electrochemical impedance tests and cycle performance testing. The charge–discharge potential range of the irregular HC negative electrode is lower than the spherical HC electrode due to the existence of lithium ion intercalation plateau, which is conducive to the sufficient utilization of the AC positive electrode. The working potential range of LIC should be controlled to realize the optimization of electrochemical performance of LIC. LIC-IH at the working potential range of 2.0-4.0 V exhibits the optimal electrochemical performance, high energy density up to 85.7 Wh kg −1 and power density as high as 7.6 kW kg −1 (based on active material mass of two electrodes), excellent capacity retention about 96.0% after 5000 cycles.

Use of thermal neutron reflection method for chemical analysis of bulk samples

International Nuclear Information System (INIS)

Papp, A.; Csikai, J.

2014-01-01

Microscopic, σ β , and macroscopic, Σ β , reflection cross-sections of thermal neutrons averaged over bulk samples as a function of thickness (z) are given. The σ β values are additive even for bulk samples in the z=0.5–8 cm interval and so the σ βmol (z) function could be given for hydrogenous substances, including some illicit drugs, explosives and hiding materials of ∼1000 cm 3 dimensions. The calculated excess counts agree with the measured R(z) values. For the identification of concealed objects and chemical analysis of bulky samples, different neutron methods need to be used simultaneously. - Highlights: • Check the proposed analytical expression for the description of the flux. • Determination of the reflection cross-sections averaged over bulk samples. • Data rendered to estimate the excess counts for various materials

Use of thermal neutron reflection method for chemical analysis of bulk samples

Energy Technology Data Exchange (ETDEWEB)

Papp, A., E-mail: papppa@atomki.hu [Institute of Nuclear Research of the Hungarian Academy of Sciences, (ATOMKI), 4001 Debrecen, Pf. 51 (Hungary); Csikai, J. [Institute of Nuclear Research of the Hungarian Academy of Sciences, (ATOMKI), 4001 Debrecen, Pf. 51 (Hungary); Institute of Experimental Physics, University Debrecen (IEP), 4010 Debrecen-10, Pf. 105 (Hungary)

2014-09-11

Microscopic, σ{sub β}, and macroscopic, Σ{sub β}, reflection cross-sections of thermal neutrons averaged over bulk samples as a function of thickness (z) are given. The σ{sub β} values are additive even for bulk samples in the z=0.5–8 cm interval and so the σ{sub βmol}(z) function could be given for hydrogenous substances, including some illicit drugs, explosives and hiding materials of ∼1000 cm{sup 3} dimensions. The calculated excess counts agree with the measured R(z) values. For the identification of concealed objects and chemical analysis of bulky samples, different neutron methods need to be used simultaneously. - Highlights: • Check the proposed analytical expression for the description of the flux. • Determination of the reflection cross-sections averaged over bulk samples. • Data rendered to estimate the excess counts for various materials.

Bi2212 HTS Tubular Bulk with Conical Shape for Current Lead

International Nuclear Information System (INIS)

Tamura, H; Mito, T; Yamada, Y; Watanabe, M; Ohkubo, J; Heller, R

2006-01-01

Current leads using HTS material have been developed for application in a large scale superconducting magnet system. Tokai University and NIFS have developed Bi2212 tubular bulk which was prepared by a diffusion process. 8 kA of maximum transport current was achieved by a tubular bulk with a cylindrical shape. The maximum current was estimated to be 2 kA at 50 K for this tubular bulk. A current lead can be designed with this bulk the warm end of the HTS part being at 50 K and the cold end at 4.2 K. Under this condition, the cross section of the cold end of the bulk can be reduced. This type of HTS bulk has a great potential for flexible design since the Bi2212 layer can be reacted on the surface of any shapes of substrate. If a conical shaped HTS bulk was made, it could be an advantage for heat leakage to the cold end. To confirm this effect, we have made two types of conical bulk. The transport current of the specimen exceeds 7 kA at 4.2 K and 4 kA of stable current flow was achieved with a warm end temperature of 50 K

Bulk viscous matter-dominated Universes: asymptotic properties

Energy Technology Data Exchange (ETDEWEB)

Avelino, Arturo [Departamento de Física, Campus León, Universidad de Guanajuato, León, Guanajuato (Mexico); García-Salcedo, Ricardo [Centro de Investigacion en Ciencia Aplicada y Tecnologia Avanzada - Legaria del IPN, México D.F. (Mexico); Gonzalez, Tame [Departamento de Ingeniería Civil, División de Ingeniería, Universidad de Guanajuato, Guanajuato (Mexico); Nucamendi, Ulises [Instituto de Física y Matemáticas, Universidad Michoacana de San Nicolás de Hidalgo, Edificio C-3, Ciudad Universitaria, CP. 58040 Morelia, Michoacán (Mexico); Quiros, Israel, E-mail: avelino@fisica.ugto.mx, E-mail: rigarcias@ipn.mx, E-mail: tamegc72@gmail.com, E-mail: ulises@ifm.umich.mx, E-mail: iquiros6403@gmail.com [Departamento de Matemáticas, Centro Universitario de Ciencias Exactas e Ingenierías (CUCEI), Corregidora 500 S.R., Universidad de Guadalajara, 44420 Guadalajara, Jalisco (Mexico)

2013-08-01

By means of a combined use of the type Ia supernovae and H(z) data tests, together with the study of the asymptotic properties in the equivalent phase space — through the use of the dynamical systems tools — we demonstrate that the bulk viscous matter-dominated scenario is not a good model to explain the accepted cosmological paradigm, at least, under the parametrization of bulk viscosity considered in this paper. The main objection against such scenarios is the absence of conventional radiation and matter-dominated critical points in the phase space of the model. This entails that radiation and matter dominance are not generic solutions of the cosmological equations, so that these stages can be implemented only by means of unique and very specific initial conditions, i. e., of very unstable particular solutions. Such a behavior is in marked contradiction with the accepted cosmological paradigm which requires of an earlier stage dominated by relativistic species, followed by a period of conventional non-relativistic matter domination, during which the cosmic structure we see was formed. Also, we found that the bulk viscosity is positive just until very late times in the cosmic evolution, around z < 1. For earlier epochs it is negative, been in tension with the local second law of thermodynamics.

Brane big bang brought on by a bulk bubble

International Nuclear Information System (INIS)

Gen, Uchida; Ishibashi, Akihiro; Tanaka, Takahiro

2002-01-01

We propose an alternative inflationary universe scenario in the context of Randall-Sundrum braneworld cosmology. In this new scenario the existence of extra dimension(s) plays an essential role. First, the brane universe is initially in the inflationary phase driven by the effective cosmological constant induced by a small mismatch between the vacuum energy in the five-dimensional bulk and the brane tension. This mismatch arises since the bulk is initially in a false vacuum. Then, false vacuum decay occurs, nucleating a true vacuum bubble with negative energy inside the bulk. The nucleated bubble expands in the bulk and consequently hits the brane, causing a hot big-bang brane universe of the Randall-Sundrum type. Here, the termination of the inflationary phase is due to the change of the bulk vacuum energy. The bubble kinetic energy heats up the universe. As a simple realization, we propose a model in which we assume an interaction between the brane and the bubble. We derive the constraints on the model parameters taking into account the following requirements: solving the flatness problem, no force which prohibits the bubble from colliding with the brane, a sufficiently high reheating temperature for the standard nucleosynthesis to work, and the recovery of Newton's law up to 1 mm. We find that a fine-tuning is needed in order to satisfy the first and the second requirements simultaneously, although the other constraints are satisfied in a wide range of the model parameters

Predicting fiber refractive index from a measured preform index profile

Science.gov (United States)

Kiiveri, P.; Koponen, J.; Harra, J.; Novotny, S.; Husu, H.; Ihalainen, H.; Kokki, T.; Aallos, V.; Kimmelma, O.; Paul, J.

2018-02-01

When producing fiber lasers and amplifiers, silica glass compositions consisting of three to six different materials are needed. Due to the varying needs of different applications, substantial number of different glass compositions are used in the active fiber structures. Often it is not possible to find material parameters for theoretical models to estimate thermal and mechanical properties of those glass compositions. This makes it challenging to predict accurately fiber core refractive index values, even if the preform index profile is measured. Usually the desired fiber refractive index value is achieved experimentally, which is expensive. To overcome this problem, we analyzed statistically the changes between the measured preform and fiber index values. We searched for correlations that would help to predict the Δn-value change from preform to fiber in a situation where we don't know the values of the glass material parameters that define the change. Our index change models were built using the data collected from preforms and fibers made by the Direct Nanoparticle Deposition (DND) technology.

Short communication: Prevalence of methicillin resistance in coagulase-negative staphylococci and Staphylococcus aureus isolated from bulk milk on organic and conventional dairy farms in the United States.

Science.gov (United States)

Cicconi-Hogan, K M; Belomestnykh, N; Gamroth, M; Ruegg, P L; Tikofsky, L; Schukken, Y H

2014-05-01

The objective of this study was to evaluate the presence of methicillin-resistant Staphylococcus aureus and coagulase-negative Staphylococcus spp. in bulk tank milk samples from 288 organic and conventional dairy farms located in New York, Wisconsin, and Oregon from March 2009 to May 2011. Due to recent publications reporting the presence mecC (a mecA homolog not detected by traditional mecA-based PCR methods), a combination of genotypic and phenotypic approaches was used to enhance the recovery of methicillin-resistant organisms from bulk tank milk. In total, 13 isolates were identified as methicillin resistant: Staph. aureus (n=1), Staphylococcus sciuri (n=5), Staphylococcus chromogenes (n=2), Staphylococcus saprophyticus (n=3), Staphylococcus agnetis (n=1), and Macrococcus caseolyticus (n=1). The single methicillin-resistant Staph. aureus isolate was identified from an organic farm in New York, for an observed 0.3% prevalence at the farm level. The methicillin-resistant coagulase-negative staphylococci prevalence was 2% in the organic population and 5% in the conventional population. We did not identify mecC in any of the isolates from our population. Of interest was the relatively high number of methicillin-resistant Staph. sciuri recovered, as the number of isolates from our study was considerably higher than those recovered from other recent studies that also assessed milk samples. Our research suggests that the presence of a potential methicillin-resistant Staphylococcus reservoir in milk, and likely the dairy farm population in the United States, is independent of the organic or conventional production system. Copyright © 2014 American Dairy Science Association. Published by Elsevier Inc. All rights reserved.

Transition between bulk and surface refractive index sensitivity of micro-cavity in-line Mach-Zehnder interferometer induced by thin film deposition.

Science.gov (United States)

Śmietana, Mateusz; Janik, Monika; Koba, Marcin; Bock, Wojtek J

2017-10-16

In this work we discuss the refractive index (RI) sensitivity of a micro-cavity in-line Mach-Zehnder interferometer in the form of a cylindrical hole (40-50 μm in diameter) fabricated in a standard single-mode optical fiber using a femtosecond laser. The surface of the micro-cavity was coated with up to 400 nm aluminum oxide thin film using the atomic layer deposition method. Next, the film was progressively chemically etched and the influence on changes in the RI of liquid in the micro-cavity was determined at different stages of the experiment, i.e., at different thicknesses of the film. An effect of transition between sensitivity to the film thickness (surface) and the RI of liquid in the cavity (bulk) is demonstrated for the first time. We have found that depending on the interferometer working conditions determined by thin film properties, the device can be used for investigation of phenomena taking place at the surface, such as in case of specific label-free biosensing applications, or for small-volume RI analysis as required in analytical chemistry.

Microtensile bond strength of bulk-fill restorative composites to dentin.

Science.gov (United States)

Mandava, Jyothi; Vegesna, Divya-Prasanna; Ravi, Ravichandra; Boddeda, Mohan-Rao; Uppalapati, Lakshman-Varma; Ghazanfaruddin, M D

2017-08-01

To facilitate the easier placement of direct resin composite in deeper cavities, bulk fill composites have been introduced. The Mechanical stability of fillings in stress bearing areas restored with bulk-fill resin composites is still open to question, since long term clinical studies are not available so far. Thus, the objective of the study was to evaluate and compare the microtensile bond strength of three bulk-fill restorative composites with a nanohybrid composite. Class I cavities were prepared on sixty extracted mandibular molars. Teeth were divided into 4 groups (n= 15 each) and in group I, the prepared cavities were restored with nanohybrid (Filtek Z250 XT) restorative composite in an incremental manner. In group II, III and IV, the bulk-fill composites (Filtek, Tetric EvoCeram, X-tra fil bulk-fill restoratives) were placed as a 4 mm single increment and light cured. The restored teeth were subjected to thermocycling and bond strength testing was done using instron testing machine. The mode of failure was assessed by scanning electron microscope (SEM). The bond strength values obtained in megapascals (MPa) were subjected to statistical analysis, using SPSS/PC version 20 software.One-way ANOVA was used for groupwise comparison of the bond strength. Tukey's Post Hoc test was used for pairwise comparisons among the groups. The highest mean bond strength was achieved with Filtek bulk-fill restorative showing statistically significant difference with Tetric EvoCeram bulk-fill ( p composites. Adhesive failures are mostly observed with X-tra fil bulk fill composites, whereas mixed failures are more common with other bulk fill composites. Bulk-fill composites exhibited adequate bond strength to dentin and can be considered as restorative material of choice in posterior stress bearing areas. Key words: Bond strength, Bulk-fill restoratives, Configuration factor, Polymerization shrinkage.

Hydrogen-induced high damping of bulk metallic glasses

International Nuclear Information System (INIS)

Hasegawa, M.

2009-01-01

There are two important topics concerned with the recent researches on the damping materials of hydrogenated metallic glasses (HMGs). One is the mechanism of the high hydrogen-induced internal friction of HMGs. The other is the materials processing of 'bulk' HMGs for engineering. This article describes the summary of our recent studies on these topics. The first one is closely related to the local structure of the metallic glasses. Therefore, our recent results on the intermediate-range local structure of the simple two Zr-based metallic glasses are described, which has been clarified by the Voronoi analysis using the experimental data of the neutron diffraction measurements. The hydrogen-induced internal friction of HMGs is also discussed on the basis of these recent results of the local structure of the metallic glasses. In terms of the second topic, the first successful preparation of heavily hydrogenated Zr-based bulk HMG rods without hydrogen-induced surface embrittlement is described. They are prepared by a powder-compact-melting and liquid-casting process using Zr-Al-Ni-Cu metallic glass and ZrH 2 powders as the starting materials. It has been found that they have high damping properties.

Bulk Soil Organic Matter d2H as a Precipitation Proxy

Science.gov (United States)

Williams, E. K.; Terwilliger, V. J.; Nakamoto, B. J.; Berhe, A. A.; Fogel, M. L.

2016-12-01

The stable hydrogen isotopic composition (d2H) of leaf waxes have traditionally been used to infer modern and paleoclimate precipitation sources. However, the extent to which evapotranspiration of leaf waters affects the d2H of plant leaf waxes remains hotly contested with offsets varying between species. Because of the relative importance of root organic matter contribution to bulk soil pools compared to litter/leaves and the minimal fractionation between soil water and root material, it is plausible that bulk soil organic matter d2H may be an option for modern and paleoclimate precipitation reconstructions. In this study, we analyzed the non-exchangeable d2H composition of roots, litter, leaves, and bulk soils along an elevation gradient in the southern Sierra Nevada range (USA). Our results show a consistent offset of 30 ± 3‰ in bulk soil organic matter in surface soils from the measured precipitation. This consistent relationship with precipitation was not found in any of the other organic materials that we measured and implies that d2H bulk soil organic matter can record precipitation signals regardless of above-ground species composition. Additionally, we utilized physical density fractionation to determine which fractions (which vary in level of mineral association and in turnover time) of the soil control this relationship. These findings and how this relationship holds with depth will be presented in conjunction with data from a soil profile on the Ethiopian plateau spanning 6000 years.

Millimeter wave surface resistance of grain-aligned Y1Ba2Cu3O(x) bulk material

International Nuclear Information System (INIS)

Wosik, J.; Kranenburg, R.A.; Wolfe, J.C.; Selvamanickam, V.; Salama, K.

1990-04-01

Measurements are reported of the millimeter-wave surface resistance of grain-aligned YBa2Cu3O(x) bulk material grown by a liquid-phase process. The measurements were performed by replacing the endplate of a TE(011) cylindrical copper cavity with the superconducting sample. Surface resistance was measured for samples with surfaces oriented perpendicular and parallel to the c-axis of the grains. For the parallel configuration, the surface resistance at 77 K and 80 GHz is given. For a very well-aligned sample with a very low density of Y2BaCuO(y) precipitates, measured in the perpendicular configuration, the transition width (10-90 percent) is about 2 K and the surface resistance is derived at 88 K. The effect of microstructure on surface resistance is discussed. 19 refs

Bulk oil clauses

International Nuclear Information System (INIS)

Gough, N.

1993-01-01

The Institute Bulk Oil Clauses produced by the London market and the American SP-13c Clauses are examined in detail in this article. The duration and perils covered are discussed, and exclusions, adjustment clause 15 of the Institute Bulk Oil Clauses, Institute War Clauses (Cargo), and Institute Strikes Clauses (Bulk Oil) are outlined. (UK)

The Polymerization of MMA and ST to Prepare Material with Gradient Refractive Index in Electric Field

Directory of Open Access Journals (Sweden)

Yao Huang

2015-01-01

Full Text Available Light scattering material with gradient refractive index was prepared under the electrical field by taking methyl methacrylate (MMA monomer as the matrix with the addition of a little preheated styrene (ST and peroxidation benzoin formyl (BPO. The material obtained under electrical field presented different transmittance and molecular weight at different parts of the cylindrical sample along the axis of the direction of electric field which led to the layering phenomenon and gradient refractive index. The disparity of molecular weight between different layers can be as much as 230 thousand. There were several peaks in the figure of GPC test of the sample under electric field. This proved that there were polymers with different molecular weights in the sample. Therefore, it can be concluded that electrical field has a significant effect on polymerization.

Self-healing in carbon nitride evidenced as material inflation and superlubric behavior.

Science.gov (United States)

Bakoglidis, Konstantinos D; Palisaitis, Justinas; Dos Santos, Renato Batista; Rivelino, Roberto; Persson, Per O Å; Gueorguiev, Gueorgui K; Hultman, Lars

2018-05-01

All known materials wear under extended mechanical contacting. Superlubricity may present solutions, but is an expressed mystery in C-based materials. We report negative wear of carbon nitride films; a wear-less condition with mechanically-induced material inflation at the nanoscale and friction coefficient approaching ultralow values (0.06). Superlubricity in carbon nitride is expressed as C-N bond breaking for reduced coupling between graphitic-like sheets and eventual N 2 desorption. The transforming surface layer acts as a solid lubricant, while the film bulk retains its high elasticity. The present findings offer new means for materials design at the atomic level, and for property optimization in wear-critical applications like magnetic reading devices or nanomachines.

Creep deformation of restorative resin-composites intended for bulk-fill placement.

Science.gov (United States)

El-Safty, S; Silikas, N; Watts, D C

2012-08-01

To determine the creep deformation of several "bulk-fill" resin-composite formulations in comparison with some other types. Six resin-composites; four bulk-fill and two conventional were investigated. Stainless steel split molds (4 mm × 6 mm) were used to prepare cylindrical specimens for creep testing. Specimens were thoroughly irradiated with 650 mW cm(-2). A total of 10 specimens for each material were divided into two groups (n = 5) according to the storage condition; Group A stored dry at 37 °C for 24h and Group B stored in distilled water at 37 °C in an incubator for 24h. Each specimen was loaded (20 MPa) for 2h and unloaded for 2h. The strain deformation was recorded continuously for 4h. Statistical analysis was performed using a two-way ANOVA followed by one-way ANOVA and the Bonferroni post hoc test at a significance level of a = 0.05. The maximum creep strain % ranged from 0.72% up to 1.55% for Group A and the range for Group B increased from 0.79% up to 1.80% due to water sorption. Also, the permanent set ranged from 0.14% up to 0.47% for Group A and from 0.20% up to 0.59% for Group B. Dependent on the material and storage condition, the percentage of creep strain recovery ranged between 64% and 81%. Increased filler loading in the bulk-fill materials decreased the creep strain magnitude. Creep deformation of all studied resin-composites increased with wet storage. The "bulk-fill" composites exhibited an acceptable creep deformation and within the range exhibited by other resin-composites. Copyright © 2012 Academy of Dental Materials. Published by Elsevier Ltd. All rights reserved.

Superconductors, analysis and applications, with special reference to the utilisation of bulk (Re)BCO materials

Energy Technology Data Exchange (ETDEWEB)

Coombs, T.A., E-mail: tac1000@cam.ac.u [University of Cambridge, Department of Engineering, Trumpington Street, Cambridge CB2 1PZ (United Kingdom)

2010-11-01

The Electrical Power and Energy Conversion (EPEC) superconductivity group at Cambridge University has been working on the application of superconductivity to large scale devices. This work is taking place over a range of areas which cover FCLs, motors and generators, SMES, accelerator magnets and MRI. The research is underpinned by advanced modelling techniques using both pure Critical State models and E-J models to analyse the behaviour of the superconductors. As part of the device design we are concentrating on the analysis of AC losses in complicated geometries such as are found in motor windings and the magnetisation of bulk superconductors to enable their full potential to be realised. We are interested in the full range of high-temperature superconductors and have measured and predicted the performance of YBCO, MgB{sub 2} and BSCCO at a range of temperatures and in wire, tape and bulk forms. This paper concentrates on recent work which includes: modelling of coils using formulations based on H and A. A critical state model for the analysis of coils in SMES; crossed field effects in bulk superconductors; a magnetic model together with experimental results which explain and describe the method of flux pumping whereby a bulk superconductor can be magnetised to a high flux density using a repeatedly applied field of low flux density and finally a new configuration for MRI magnets

MgO-templated carbon as a negative electrode material for Na-ion capacitors

Science.gov (United States)

Kado, Yuya; Soneda, Yasushi

2016-12-01

In this study, MgO-templated carbon with different pore structures was investigated as a negative electrode material for Na-ion capacitors. With increasing the Brunauer-Emmett-Teller surface area, the irreversible capacity increased, and the coulombic efficiency of the 1st cycle decreased because of the formation of solid electrolyte interface layers. MgO-templated carbon annealed at 1000 °C exhibited the highest capacity and best rate performance, suggesting that an appropriate balance between surface area and crystallinity is imperative for fast Na-ion storage, attributed to the storage mechanism: combination of non-faradaic electric double-layer capacitance and faradaic Na intercalation in the carbon layers. Finally, a Na-ion capacitor cell using MgO-templated carbon and activated carbon as the negative and positive electrodes, respectively, exhibited an energy density at high power density significantly greater than that exhibited by the cell using a commercial hard carbon negative electrode.

Study of the association of atmospheric temperature and relative humidity with bulk tank milk somatic cell count in dairy herds using Generalized additive mixed models.

Science.gov (United States)

Testa, Francesco; Marano, Giuseppe; Ambrogi, Federico; Boracchi, Patrizia; Casula, Antonio; Biganzoli, Elia; Moroni, Paolo

2017-10-01

Elevated bulk tank milk somatic cell count (BMSCC) has a negative impact on milk production, milk quality, and animal health. Seasonal increases in herd level somatic cell count (SCC) are commonly associated with elevated environmental temperature and humidity. The Temperature Humidity Index (THI) has been developed to measure general environmental stress in dairy cattle; however, additional work is needed to determine a specific effect of the heat stress index on herd-level SCC. Generalized Additive Model methods were used for a flexible exploration of the relationships between daily temperature, relative humidity, and bulk milk somatic cell count. The data consist of BMSCC and meteorological recordings collected between March 2009 and October 2011 of 10 dairy farms. The results indicate that, an average increase of 0.16% of BMSCC is expected for an increase of 1°C degree of temperature. A complex relationship was found for relative humidity. For example, increase of 0.099%, 0.037% and 0.020% are expected in correspondence to an increase of relative humidity from 50% to 51%, 80% to 81%; and 90% to 91%, respectively. Using this model, it will be possible to provide evidence-based advice to dairy farmers for the use of THI control charts created on the basis of our statistical model. Copyright © 2017 Elsevier Ltd. All rights reserved.

Analytical solution for wave propagation through a graded index interface between a right-handed and a left-handed material

OpenAIRE

Dalarsson, Mariana; Tassin, Philippe

2012-01-01

We have investigated the transmission and reflection properties of structures incorporating left-handed materials with graded index of refraction. We present an exact analytical solution to Helmholtz' equation for a graded index profile changing according to a hyperbolic tangent function along the propagation direction. We derive expressions for the field intensity along the graded index structure, and we show excellent agreement between the analytical solution and the corresponding results o...

Fabrication and Optical Measurements of Nanoscale Meta-Materials: Terahertz and Beyond

OpenAIRE

Martin, Michael C.; Hao, Zhao; Liddle, Alex; Anderson, Erik H.; Padilla, Willie J.; Schurig, David; Smith, David R.

2005-01-01

Recently, artificial meta-materials have been reported [1] that have a negative index of refraction, which allows a homogeneous flat slab of the material to behave as a perfect lens [2], possibly even creating sub-diffraction limited focusing. These novel artificial materials have numerous potential applications in science, technology, and medicine [3],especially if their novel behavior can be extended to the technologically critical near-infrared and visible region.The meta-materials co...

27 CFR 24.301 - Bulk still wine record.

Science.gov (United States)

2010-04-01

... produces or receives still wine in bond, (including wine intended for use as distilling material or vinegar.... The bulk still wine record will contain the following: (a) The volume produced by fermentation in wine... fermentation, amelioration, sweetening, addition of spirits, blending; (d) The volume of wine used and produced...

Solid state properties from bulk to nano

CERN Document Server

Dresselhaus, Mildred; Cronin, Stephen; Gomes Souza Filho, Antonio

2018-01-01

This book fills a gap between many of the basic solid state physics and materials science books that are currently available. It is written for a mixed audience of electrical engineering and applied physics students who have some knowledge of elementary undergraduate quantum mechanics and statistical mechanics. This book, based on a successful course taught at MIT, is divided pedagogically into three parts: (I) Electronic Structure, (II) Transport Properties, and (III) Optical Properties. Each topic is explained in the context of bulk materials and then extended to low-dimensional materials where applicable. Problem sets review the content of each chapter to help students to understand the material described in each of the chapters more deeply and to prepare them to master the next chapters.

Bulk characterization of pharmaceutical powders by low-pressure compression

DEFF Research Database (Denmark)

Sørensen, A.H.; Sonnergaard, Jørn; Hovgaard, L.

2005-01-01

Low-pressure compression of pharmaceutical powders using small amounts of sample (50 mg) was evaluated as an alternative to traditional bulk powder characterization by tapping volumetry. Material parameters were extrapolated directly from the compression data and by fitting with the Walker...

Synthesis and magnetic properties of bulk transparent PMMA/Fe-oxide nanocomposites

Science.gov (United States)

Li, Shanghua; Qin, Jian; Fornara, Andrea; Toprak, Muhammet; Muhammed, Mamoun; Kim, Do Kyung

2009-05-01

PMMA/Fe-oxide nanocomposites are fabricated by a chemical method. Monodispersed Fe-oxide nanoparticles are well dispersed in the PMMA matrix by in situ polymerization, resulting in a bulk transparent polymeric nanocomposite. The magnetic behavior of the PMMA/Fe-oxide nanocomposites is investigated. The transparent PMMA/Fe-oxide nanocomposite has potentially interesting magneto-optic applications without compromising the advantages of a lightweight, noncorrosive polymeric material with very high transparency even for bulk samples.

Synthesis and magnetic properties of bulk transparent PMMA/Fe-oxide nanocomposites

International Nuclear Information System (INIS)

Li Shanghua; Qin Jian; Fornara, Andrea; Toprak, Muhammet; Muhammed, Mamoun; Kim, Do Kyung

2009-01-01

PMMA/Fe-oxide nanocomposites are fabricated by a chemical method. Monodispersed Fe-oxide nanoparticles are well dispersed in the PMMA matrix by in situ polymerization, resulting in a bulk transparent polymeric nanocomposite. The magnetic behavior of the PMMA/Fe-oxide nanocomposites is investigated. The transparent PMMA/Fe-oxide nanocomposite has potentially interesting magneto-optic applications without compromising the advantages of a lightweight, noncorrosive polymeric material with very high transparency even for bulk samples.

Fundamentals of negative refractive index optical trapping: forces and radiation pressures exerted by focused Gaussian beams using the generalized Lorenz-Mie theory.

Science.gov (United States)

Ambrosio, Leonardo A; Hernández-Figueroa, Hugo E

2010-11-04

Based on the generalized Lorenz-Mie theory (GLMT), this paper reveals, for the first time in the literature, the principal characteristics of the optical forces and radiation pressure cross-sections exerted on homogeneous, linear, isotropic and spherical hypothetical negative refractive index (NRI) particles under the influence of focused Gaussian beams in the Mie regime. Starting with ray optics considerations, the analysis is then extended through calculating the Mie coefficients and the beam-shape coefficients for incident focused Gaussian beams. Results reveal new and interesting trapping properties which are not observed for commonly positive refractive index particles and, in this way, new potential applications in biomedical optics can be devised.

Proton beam micromachined buried microchannels in negative tone resist materials

International Nuclear Information System (INIS)

Rajta, I.; Chatzichristidi, M.; Baradacs, E.; Cserhati, C.; Raptis, I.; Manoli, K.; Valamontes, E.S.

2007-01-01

In the present work the Atomki, Debrecen microprobe facility has been used to write long tilted structures by 2 MeV protons. For the formation of the structures, two exposures have been carried out at +20 o and -20 o using a goniometer stage sample holder. The tilted structures were resolved in the negative tone resist materials SU-8 and ADEPR (an aqueous base developable chemically amplified resist). The length of the microchannels was varied between 100 μm and 1000 μm, the wall thickness was less than 10 μm. By applying the developed methodology it was possible to resolve the desired layout through the whole length of the channel

The effect of grain size and cement content on index properties of weakly solidified artificial sandstones

Science.gov (United States)

Atapour, Hadi; Mortazavi, Ali

2018-04-01

The effects of textural characteristics, especially grain size, on index properties of weakly solidified artificial sandstones are studied. For this purpose, a relatively large number of laboratory tests were carried out on artificial sandstones that were produced in the laboratory. The prepared samples represent fifteen sandstone types consisting of five different median grain sizes and three different cement contents. Indices rock properties including effective porosity, bulk density, point load strength index, and Schmidt hammer values (SHVs) were determined. Experimental results showed that the grain size has significant effects on index properties of weakly solidified sandstones. The porosity of samples is inversely related to the grain size and decreases linearly as grain size increases. While a direct relationship was observed between grain size and dry bulk density, as bulk density increased with increasing median grain size. Furthermore, it was observed that the point load strength index and SHV of samples increased as a result of grain size increase. These observations are indirectly related to the porosity decrease as a function of median grain size.

On the gravitational collapse of a gas cloud in the presence of bulk viscosity

International Nuclear Information System (INIS)

Carlevaro, Nakia; Montani, Giovanni

2005-01-01

We analyse the effects induced by the bulk (or second) viscosity on the dynamics associated with the extreme gravitational collapse. The aim of the work is to investigate whether the presence of viscous corrections to the evolution of a collapsing gas cloud influences the top-down fragmentation process. To this end, we generalize the approach presented by Hunter (1962 Astrophys. J. 136 594) to include in the dynamics of the (uniform and spherically symmetric) cloud the negative pressure contribution associated with the bulk viscosity phenomenology. Within the framework of a Newtonian approach (whose range of validity is outlined), we extend to the viscous case either the Lagrangian or the Eulerian motion of the system addressed in Hunter (1962 Astrophys. J. 136 594) and we treat the asymptotic evolution in correspondence with a viscosity coefficient of the form ζ = ζ 0 ρ 5/6 (ρ being the cloud density and ζ 0 = const). We show how the adiabatic-like behaviour of the gas (i.e. when the polytropic index γ takes values 4/3 < γ ≤ 5/3) is deeply influenced by viscous correction when its collapse reaches the extreme regime toward the singularity. In fact, for sufficiently large viscous contributions, density contrasts associated with a given scale of the fragmentation process acquire, asymptotically, a vanishing behaviour which prevents the formation of sub-structures. Since in the non-dissipative case density contrasts diverge (except for the purely adiabatic behaviour γ = 5/3 in which they remain constant), we can conclude that in the adiabatic-like collapse the top-down mechanism of structure formation is suppressed as soon as enough strong viscous effects are taken into account. Such a feature is not present in the isothermal-like (i.e. 1 ≤ γ < 4/3) collapse because the sub-structure formation is yet present and outlines the same behaviour as in the non-viscous case. We emphasize that in the adiabatic-like collapse the bulk viscosity is also responsible

Sink strengths of dislocations taking into account bulk recombination effects

International Nuclear Information System (INIS)

Steinbach, E.

1988-01-01

The applicability of the rate theory to describe radiation damage processes is closely associated with the calculation of the various sink strengths. In this connection the effect of bulk recombination is usually neglected, because of the complexity of the problem. For this reason we present in this paper, for the first time, by means of the rigorous elastic-field model of a dislocation embedded in a lossy continuum, analytic expressions for the diffusion flux of irradiation-induced point defects into a dislocation, taking into account the elastic interaction, additional sinks and higher order bulk recombination effects. The resulting self-consistent formulae for the dislocation sink strengths clearly demonstrate the importance of the bulk recombination for the micro-structures of irradiated materials. In conjunction with the Harwell computer code VS5 it became clear that this new dislocation bias also leads to a change in the macrostructural observables. The order of magnitude of this effect emphasizes that neglecting bulk recombination as a general principle is not justified

Plasmon response of a metal-semiconductor multilayer 4π-spiral as a negative-index metamaterial

Energy Technology Data Exchange (ETDEWEB)

Ahmadivand, Arash, E-mail: aahma011@fiu.edu; Pala, Nezih [Florida International University, Department of Electrical and Computer Engineering (United States)

2014-12-15

In this study, we investigate the optical response and plasmonic features of a multilayer 4π-spiral composed of metal-semiconductor arms, numerically, by employing a finite-difference time-domain method. We verified that the proposed structure is able to support strong plasmon and Fano resonances in the circular arms. We showed that the negative polarizability of the spiral provides an opportunity to consider the examined 4π-spiral structure as a meta-atom. Quantifying the effective refractive index of the structure for the presence of various semiconductor substances such as Si, GaP, and InP, we obtained the highest possible value for the associated figure of merit (FOM). Ultimately, for a finite spiral structure with a compositional and multilayer arrangement of Au and GaP arms, the FOM is determined as approximately ∼62.3.

Ultrafast laser induced electronic and structural modifications in bulk fused silica

Energy Technology Data Exchange (ETDEWEB)

Mishchik, K.; D' Amico, C.; Velpula, P. K.; Mauclair, C.; Boukenter, A.; Ouerdane, Y.; Stoian, R. [Laboratoire Hubert Curien, UMR 5516 CNRS, Université de Lyon, Université Jean Monnet, 42000 Saint Etienne (France)

2013-10-07

Ultrashort laser pulses can modify the inner structure of fused silica, generating refractive index changes varying from soft positive (type I) light guiding forms to negative (type II) values with void presence and anisotropic sub-wavelength modulation. We investigate electronic and structural material changes in the type I to type II transition via coherent and incoherent secondary light emission reflecting free carrier behavior and post-irradiation material relaxation in the index change patterns. Using phase contrast microscopy, photoluminescence, and Raman spectroscopy, we determine in a space-resolved manner defect formation, redistribution and spatial segregation, and glass network reorganization paths in conditions marking the changeover between type I and type II photoinscription regimes. We first show characteristic patterns of second harmonic generation in type I and type II traces, indicating the collective involvement of free carriers and polarization memory. Second, incoherent photoemission from resonantly and non-resonantly excited defect states reveals accumulation of non-bridging oxygen hole centers (NBOHCs) in positive index domains and oxygen deficiency centers (ODCs) with O{sub 2}{sup −} ions segregation in void-like regions and in the nanostructured domains, reflecting the interaction strength. Complementary Raman investigations put into evidence signatures of the different environments where photo-chemical densification (bond rearrangements) and mechanical effects can be indicated. NBOHCs setting in before visible index changes serve as precursors for subsequent compaction build-up, indicating a scenario of cold, defect-assisted densification for the soft type I irradiation regime. Additionally, we observe hydrodynamic effects and severe bond-breaking in type II zones with indications of phase transition. These observations illuminate densification paths in fused silica in low power irradiation regimes, and equally in energetic ranges

First principles study of lithium insertion in bulk silicon

KAUST Repository

Wan, Wenhui; Zhang, Qianfan; Cui, Yi; Wang, Enge

2010-01-01

Si is an important anode material for the next generation of Li ion batteries. Here the energetics and dynamics of Li atoms in bulk Si have been studied at different Li concentrations on the basis of first principles calculations. It is found

Unusual negative magnetoresistance in Bi2Se3-ySy topological insulator under perpendicular magnetic field

Science.gov (United States)

Singh, Rahul; Gangwar, Vinod K.; Daga, D. D.; Singh, Abhishek; Ghosh, A. K.; Kumar, Manoranjan; Lakhani, A.; Singh, Rajeev; Chatterjee, Sandip

2018-03-01

The magneto-transport properties of Bi2Se3-ySy were investigated. Magnetoresistance (MR) decreases with an increase in the S content, and finally, for 7% (i.e., y = 0.21) S doping, the magnetoresistance becomes negative. This negative MR is unusual as it is observed when a magnetic field is applied in the perpendicular direction to the plane of the sample. The magneto-transport behavior shows the Shubnikov-de Haas (SdH) oscillation, indicating the coexistence of surface and bulk states. The negative MR has been attributed to the non-trivial bulk conduction.

Soil microbial biomass under pine forests in the north-western Spain: influence of stand age, site index and parent material

Energy Technology Data Exchange (ETDEWEB)

Mahia, J.; Perez-Ventura, L.; Cabaneiro, A.; Diaz-Ravina, M.

2006-07-01

The effects of stand age, site index and parent material on soil biochemical properties related to biomass (extractable C, microbial C and metabolic quotient) were examined in the 0-15 cm mineral soil layers of Pinus pinaster and Pinus sylvestris stand from NW Spain. Two productivity levels (low and high site index), two ages (young and old) and two parent soil materials (granite and acid schists) were considered. The data indicated that there were differences in microbial parameters in soils under different species. In general in P. pinaster forest higher values of biochemical parameters expressed on organic C basis, were observed in the stands of high site index as compared with the low ones; in contrast, in P. sylvestris no differences among stand site index were detected. In both species different results were also observed depending on parent material and a significant effect of stand age was detected for extractable C and microbial C in P. pinaster forest developed over granite. The data seem to indicate that measured parameters may have the potential to be used as indicators of the effect of forest management on soil organic matter quality. (Author) 25 refs.

Bacterial hand contamination and transfer after use of contaminated bulk-soap-refillable dispensers.

Science.gov (United States)

Zapka, Carrie A; Campbell, Esther J; Maxwell, Sheri L; Gerba, Charles P; Dolan, Michael J; Arbogast, James W; Macinga, David R

2011-05-01

Bulk-soap-refillable dispensers are prone to extrinsic bacterial contamination, and recent studies demonstrated that approximately one in four dispensers in public restrooms are contaminated. The purpose of this study was to quantify bacterial hand contamination and transfer after use of contaminated soap under controlled laboratory and in-use conditions in a community setting. Under laboratory conditions using liquid soap experimentally contaminated with 7.51 log(10) CFU/ml of Serratia marcescens, an average of 5.28 log(10) CFU remained on each hand after washing, and 2.23 log(10) CFU was transferred to an agar surface. In an elementary-school-based field study, Gram-negative bacteria on the hands of students and staff increased by 1.42 log(10) CFU per hand (26-fold) after washing with soap from contaminated bulk-soap-refillable dispensers. In contrast, washing with soap from dispensers with sealed refills significantly reduced bacteria on hands by 0.30 log(10) CFU per hand (2-fold). Additionally, the mean number of Gram-negative bacteria transferred to surfaces after washing with soap from dispensers with sealed-soap refills (0.06 log(10) CFU) was significantly lower than the mean number after washing with contaminated bulk-soap-refillable dispensers (0.74 log(10) CFU; P soap (P soap from bulk-soap-refillable dispensers can increase the number of opportunistic pathogens on the hands and may play a role in the transmission of bacteria in public settings.

Development of Bulk Nanocrystalline Cemented Tungsten Carbide for Industrial Applicaitons

Energy Technology Data Exchange (ETDEWEB)

Z. Zak Fang, H. Y. Sohn

2009-03-10

This report contains detailed information of the research program entitled "Development of Bulk Nanocrystalline Cemented Tungsten Carbide Materials for Industrial Applications". The report include the processes that were developed for producing nanosized WC/Co composite powders, and an ultrahigh pressure rapid hot consolidation process for sintering of nanosized powders. The mechanical properties of consolidated materials using the nanosized powders are also reported.

A prognostic factor index for overall survival in patients receiving first-line chemotherapy for HER2-negative advanced breast cancer: an analysis of the ATHENA trial.

Science.gov (United States)

Llombart-Cussac, Antonio; Pivot, Xavier; Biganzoli, Laura; Cortes-Funes, Hernan; Pritchard, Kathleen I; Pierga, Jean-Yves; Smith, Ian; Thomssen, Christoph; Srock, Stefanie; Sampayo, Miguel; Cortes, Javier

2014-10-01

Evidence-based definitions of 'poor-prognosis' or 'aggressive' advanced breast cancer are lacking. We developed a prognostic factor index using data from 2203 patients treated with first-line chemotherapy plus bevacizumab for HER2-negative advanced breast cancer. The risk factors most closely associated with worse OS were: disease-free interval ≤24 months; liver metastases or ≥3 involved organ sites; prior anthracycline and/or taxane therapy; triple-negative breast cancer (TNBC); and performance status 2 or prior analgesic/corticosteroid treatment. Risk of death was increased threefold in patients with ≥3 versus ≤1 risk factors (hazard ratio 3.0 [95% CI 2.6-3.4; p < 0.001]; median 16.0 vs 38.8 months, respectively). This prognostic index may enable identification of patients with a poorer prognosis in whom more intensive systemic regimens may be appropriate. The index may also be considered in designing new trials, although it requires validation in other datasets before extrapolation to non-bevacizumab-containing therapy. ClinicalTrials.gov identifier: NCT00448591. Copyright © 2014 Elsevier Ltd. All rights reserved.

Some fundamental definitions of the elastic parameters for homogenous isotropic linear materials in road design and analysis

CSIR Research Space (South Africa)

De Beer, Morris

2008-07-01

Full Text Available - wave and ρ the material density. The elastic moduli P-wave modulus, M, is defined so that M = K + 4µ / 3 and M can then be determined by Equation 11, with a known speed Vp P MV 2 ρ = (11) It should however also... gas (such as air within compacted road materials), the adiabatic bulk modulus KS is approximately given by pKS κ= (4) Where: κ is the adiabatic index, (sometimes calledγ ); p is the pressure. In a fluid (such as moisture...

Multilayer Integrated Film Bulk Acoustic Resonators

CERN Document Server

Zhang, Yafei

2013-01-01

Multilayer Integrated Film Bulk Acoustic Resonators mainly introduces the theory, design, fabrication technology and application of a recently developed new type of device, multilayer integrated film bulk acoustic resonators, at the micro and nano scale involving microelectronic devices, integrated circuits, optical devices, sensors and actuators, acoustic resonators, micro-nano manufacturing, multilayer integration, device theory and design principles, etc. These devices can work at very high frequencies by using the newly developed theory, design, and fabrication technology of nano and micro devices. Readers in fields of IC, electronic devices, sensors, materials, and films etc. will benefit from this book by learning the detailed fundamentals and potential applications of these advanced devices. Prof. Yafei Zhang is the director of the Ministry of Education’s Key Laboratory for Thin Films and Microfabrication Technology, PRC; Dr. Da Chen was a PhD student in Prof. Yafei Zhang’s research group.

Millimeter wave surface resistance of grain-aligned Y1Ba2Cu3O(x) bulk material

Science.gov (United States)

Wosik, J.; Kranenburg, R. A.; Wolfe, J. C.; Selvamanickam, V.; Salama, K.

1991-01-01

Measurements of the millimeter wave surface resistance of grain-aligned YBa2Cu3O(x) bulk material grown by a liquid phase process are reported. The measurements were performed by replacing the endplate of a TE011 cylindrical copper cavity with the superconducting sample. Surface resistance was measured for samples with surfaces oriented perpendicular and parallel to the c-axis of the grains. It is shown that, for the parallel configuration, the surface resistance at 77 K and 80 GHz is typically near 100 milliohms. For a very well-aligned sample with a very low density of Y2BaCuO(y) precipitates, measured in the perpendicular configuration, the transition width (10-90 percent) is about 2 K, and the surface resistance is less than 50 milliohms at 88 K. The effect of microstructure on surface resistance is discussed.

Cuspal deflection and microleakage in premolar teeth restored with bulk-fill flowable resin-based composite base materials

DEFF Research Database (Denmark)

Moorthy, A; Hogg, C H; Dowling, A H

2012-01-01

To assess the cuspal deflection and cervical microleakage of standardised Class II cavities incrementally filled with a dimethacrylate RBC or bulk-fill flowable RBC bases.......To assess the cuspal deflection and cervical microleakage of standardised Class II cavities incrementally filled with a dimethacrylate RBC or bulk-fill flowable RBC bases....

Bulk delivery of explosives offers positive advantages

Energy Technology Data Exchange (ETDEWEB)

NONE

1993-09-01

The bulk delivery of precisely-formulated explosives directly to the shothole is a safe, secure and cost effective way of bringing rock to the quarry floor. This article describes several of the latest generation of Anfo trucks. The typical Anfo truck carries ammonium nitrate and fuel oil in bulk, together with several other mix constituents, including an emulsifying agent. These are designed to form the basis of a range of emulsion-type explosives. In effect, these are water in oil emulsions where the water phase consists of droplets of a saturated solution of the oxidizing material suspended in oil. The formulations may be further tailored to the shothole requirements by the addition of oils or waxes, which can alter the viscosity of the explosive. The precise and programmable controls which determine the exact quantities of materials delivered to the mixer mean that the explosive mixtures can be tailored exactly to the requirements of the blasting operation, be it the amount of rock to be dislodged, the geological conditions, or the state of the shothole - either wet or dry. 4 systems are described in detail. 3 figs.

Holographic quantum error-correcting codes: toy models for the bulk/boundary correspondence

Energy Technology Data Exchange (ETDEWEB)

Pastawski, Fernando; Yoshida, Beni [Institute for Quantum Information & Matter and Walter Burke Institute for Theoretical Physics,California Institute of Technology,1200 E. California Blvd., Pasadena CA 91125 (United States); Harlow, Daniel [Princeton Center for Theoretical Science, Princeton University,400 Jadwin Hall, Princeton NJ 08540 (United States); Preskill, John [Institute for Quantum Information & Matter and Walter Burke Institute for Theoretical Physics,California Institute of Technology,1200 E. California Blvd., Pasadena CA 91125 (United States)

2015-06-23

We propose a family of exactly solvable toy models for the AdS/CFT correspondence based on a novel construction of quantum error-correcting codes with a tensor network structure. Our building block is a special type of tensor with maximal entanglement along any bipartition, which gives rise to an isometry from the bulk Hilbert space to the boundary Hilbert space. The entire tensor network is an encoder for a quantum error-correcting code, where the bulk and boundary degrees of freedom may be identified as logical and physical degrees of freedom respectively. These models capture key features of entanglement in the AdS/CFT correspondence; in particular, the Ryu-Takayanagi formula and the negativity of tripartite information are obeyed exactly in many cases. That bulk logical operators can be represented on multiple boundary regions mimics the Rindler-wedge reconstruction of boundary operators from bulk operators, realizing explicitly the quantum error-correcting features of AdS/CFT recently proposed in http://dx.doi.org/10.1007/JHEP04(2015)163.

Faraday cage angled-etching of nanostructures in bulk dielectrics

OpenAIRE

Latawiec, Pawel; Burek, Michael J.; Sohn, Young-Ik; Lončar, Marko

2016-01-01

For many emerging optoelectronic materials, heteroepitaxial growth techniques do not offer the same high material quality afforded by bulk, single-crystal growth. However, the need for optical, electrical, or mechanical isolation at the nanoscale level often necessitates the use of a dissimilar substrate, upon which the active device layer stands. Faraday cage angled-etching (FCAE) obviates the need for these planar, thin-film technologies by enabling in-situ device release and isolation thro...

Anal Sphincter Augmentation Using Biological Material.

Science.gov (United States)

Alam, Nasra N; Narang, Sunil K; Köckerling, Ferdinand; Daniels, Ian R; Smart, Neil J

2015-01-01

The aim of this review is to provide an overview of the use of biological materials in the augmentation of the anal sphincter either as part of an overlapping sphincter repair (OSR) or anal bulking procedure. A systematic search of PubMed was conducted using the search terms "anal bulking agents," "anal sphincter repair," or "overlapping sphincter repair." Five studies using biological material as part of an overlapping sphincter repair (OSR) or as an anal bulking agent were identified. 122 patients underwent anal bulking with a biological material. Anorectal physiology was conducted in 27 patients and demonstrated deterioration in maximum resting pressure, and no significant change in maximum squeeze increment. Quality of life scores (QoLs) demonstrated improvements at 6 weeks and 6 months, but this had deteriorated at 12 months of follow up. Biological material was used in 23 patients to carry out an anal encirclement procedure. Improvements in QoLs were observed in patients undergoing OSR as well as anal encirclement using biological material. Incontinence episodes decreased to an average of one per week from 8 to 10 preoperatively. Sphincter encirclement with biological material has demonstrated improvements in continence and QoLs in the short term compared to traditional repair alone. Long-term studies are necessary to determine if this effect is sustained. As an anal bulking agent the benefits are short-term.

Suppression of bulk conductivity in InAs/GaSb broken gap composite quantum wells

Energy Technology Data Exchange (ETDEWEB)

Charpentier, Christophe; Fält, Stefan; Reichl, Christian; Nichele, Fabrizio; Nath Pal, Atindra; Pietsch, Patrick; Ihn, Thomas; Ensslin, Klaus; Wegscheider, Werner [Laboratory for Solid State Physics, ETH Zürich, 8093 Zürich (Switzerland)

2013-09-09

The two-dimensional topological insulator state in InAs/GaSb quantum wells manifests itself by topologically protected helical edge channel transport relying on an insulating bulk. This work investigates a way of suppressing bulk conductivity by using gallium source materials of different degrees of impurity concentrations. While highest-purity gallium is accompanied by clear conduction through the sample bulk, intentional impurity incorporation leads to a bulk resistance over 1 MΩ, independent of applied magnetic fields. In addition, ultra high electron mobilities for GaAs/AlGaAs structures fabricated in a molecular beam epitaxy system used for the growth of Sb-based samples are reported.

Information or resolution: Which is required from an SEM to study bulk inorganic materials?

Science.gov (United States)

Xing, Q

2016-11-01

Significant technological advances in scanning electron microscopy (SEM) have been achieved over the past years. Different SEMs can have significant differences in functionality and performance. This work presents the perspectives on selecting an SEM for research on bulk inorganic materials. Understanding materials demands quantitative composition and orientation information, and informative and interpretable images that reveal subtle differences in chemistry, orientation/structure, topography, and electronic structure. The capability to yield informative and interpretable images with high signal-to-noise ratios and spatial resolutions is an overall result of the SEM system as a whole, from the electron optical column to the detection system. The electron optical column determines probe performance. The roles of the detection system are to capture, filter or discriminate, and convert signal electrons to imaging information. The capability to control practical operating parameters including electron probe size and current, acceleration voltage or landing voltage, working distance, detector selection, and signal filtration is inherently determined by the SEM itself. As a platform for various accessories, e.g. an energy-dispersive spectrometer and an electron backscatter diffraction detector, the properties of the electron optical column, specimen chamber, and stage greatly affect the performance of accessories. Ease-of-use and ease-of-maintenance are of practical importance. It is practically important to select appropriate test specimens, design suitable imaging conditions, and analyze the specimen chamber geometry and dimensions to assess the overall functionality and performance of an SEM. For an SEM that is controlled/operated with a computer, the stable software and user-friendly interface significantly improve the usability of the SEM. SCANNING 38:864-879, 2016. © 2016 Wiley Periodicals, Inc. © Wiley Periodicals, Inc.

Bulk electric system reliability evaluation incorporating wind power and demand side management

Science.gov (United States)

Huang, Dange

Electric power systems are experiencing dramatic changes with respect to structure, operation and regulation and are facing increasing pressure due to environmental and societal constraints. Bulk electric system reliability is an important consideration in power system planning, design and operation particularly in the new competitive environment. A wide range of methods have been developed to perform bulk electric system reliability evaluation. Theoretically, sequential Monte Carlo simulation can include all aspects and contingencies in a power system and can be used to produce an informative set of reliability indices. It has become a practical and viable tool for large system reliability assessment technique due to the development of computing power and is used in the studies described in this thesis. The well-being approach used in this research provides the opportunity to integrate an accepted deterministic criterion into a probabilistic framework. This research work includes the investigation of important factors that impact bulk electric system adequacy evaluation and security constrained adequacy assessment using the well-being analysis framework. Load forecast uncertainty is an important consideration in an electrical power system. This research includes load forecast uncertainty considerations in bulk electric system reliability assessment and the effects on system, load point and well-being indices and reliability index probability distributions are examined. There has been increasing worldwide interest in the utilization of wind power as a renewable energy source over the last two decades due to enhanced public awareness of the environment. Increasing penetration of wind power has significant impacts on power system reliability, and security analyses become more uncertain due to the unpredictable nature of wind power. The effects of wind power additions in generating and bulk electric system reliability assessment considering site wind speed

Sodium Flux Growth of Bulk Gallium Nitride

Science.gov (United States)

Von Dollen, Paul Martin

This dissertation focused on development of a novel apparatus and techniques for crystal growth of bulk gallium nitride (GaN) using the sodium flux method. Though several methods exist to produce bulk GaN, none have been commercialized on an industrial scale. The sodium flux method offers potentially lower cost production due to relatively mild process conditions while maintaining high crystal quality. But the current equipment and methods for sodium flux growth of bulk GaN are generally not amenable to large-scale crystal growth or in situ investigation of growth processes, which has hampered progress. A key task was to prevent sodium loss or migration from the sodium-gallium growth melt while permitting N2 gas to access the growing crystal, which was accomplished by implementing a reflux condensing stem along with a reusable sealed capsule. The reflux condensing stem also enabled direct monitoring and control of the melt temperature, which has not been previously reported for the sodium flux method. Molybdenum-based materials were identified from a corrosion study as candidates for direct containment of the corrosive sodium-gallium melt. Successful introduction of these materials allowed implementation of a crucible-free containment system, which improved process control and can potentially reduce crystal impurity levels. Using the new growth system, the (0001) Ga face (+c plane) growth rate was >50 mum/hr, which is the highest bulk GaN growth rate reported for the sodium flux method. Omega X-ray rocking curve (?-XRC) measurements indicated the presence of multiple grains, though full width at half maximum (FWHM) values for individual peaks were 1020 atoms/cm3, possibly due to reactor cleaning and handling procedures. This dissertation also introduced an in situ technique to correlate changes in N2 pressure with dissolution of nitrogen and precipitation of GaN from the sodium-gallium melt. Different stages of N2 pressure decay were identified and linked to

Analytical solution for wave propagation through a graded index interface between a right-handed and a left-handed material.

Science.gov (United States)

Dalarsson, Mariana; Tassin, Philippe

2009-04-13

We have investigated the transmission and reflection properties of structures incorporating left-handed materials with graded index of refraction. We present an exact analytical solution to Helmholtz' equation for a graded index profile changing according to a hyperbolic tangent function along the propagation direction. We derive expressions for the field intensity along the graded index structure, and we show excellent agreement between the analytical solution and the corresponding results obtained by accurate numerical simulations. Our model straightforwardly allows for arbitrary spectral dispersion.

Natural radioactivity in building material in the European Union: robustness of the activity concentration index I and comparison with a room model.

Science.gov (United States)

Nuccetelli, C; Risica, S; D'Alessandro, M; Trevisi, R

2012-09-01

Using a wide database collected in the last 10 years, the authors have calculated the activity concentration index I for many building materials in the European Union. Suggested by a European technical guidance document, the index I has recently been adopted as a screening tool in the proposal for the new Euratom basic safety standards directive. The paper analyses the possible implications of the choice of different parameters for the computation of index I, i.e. background to be subtracted, dose criteria, etc. With the collected data an independent assessment of gamma doses was also made with an ISS room model, choosing reasonable hypotheses on the use of materials. The results of the two approaches, i.e. index I and a room model, were compared.

Isotropic Negative Thermal Expansion Metamaterials.

Science.gov (United States)

Wu, Lingling; Li, Bo; Zhou, Ji

2016-07-13

Negative thermal expansion materials are important and desirable in science and engineering applications. However, natural materials with isotropic negative thermal expansion are rare and usually unsatisfied in performance. Here, we propose a novel method to achieve two- and three-dimensional negative thermal expansion metamaterials via antichiral structures. The two-dimensional metamaterial is constructed with unit cells that combine bimaterial strips and antichiral structures, while the three-dimensional metamaterial is fabricated by a multimaterial 3D printing process. Both experimental and simulation results display isotropic negative thermal expansion property of the samples. The effective coefficient of negative thermal expansion of the proposed models is demonstrated to be dependent on the difference between the thermal expansion coefficient of the component materials, as well as on the circular node radius and the ligament length in the antichiral structures. The measured value of the linear negative thermal expansion coefficient of the three-dimensional sample is among the largest achieved in experiments to date. Our findings provide an easy and practical approach to obtaining materials with tunable negative thermal expansion on any scale.

Some fundamental definitions of the elastic parameters for homogeneous isotropic linear elastic materials in pavement design and analysis

CSIR Research Space (South Africa)

De Beer, Morris

2008-07-01

Full Text Available - wave and ρ the material density. The elastic moduli P-wave modulus, M, is defined so that M = K + 4µ / 3 and M can then be determined by Equation 11, with a known speed Vp P MV 2 ρ = (11) It should however also... gas (such as air within compacted road materials), the adiabatic bulk modulus KS is approximately given by pKS κ= (4) Where: κ is the adiabatic index, (sometimes calledγ ); p is the pressure. In a fluid (such as moisture...

The Effects of Different Drawing Materials on Children's Drawings of Positive and Negative Human Figures

Science.gov (United States)

Burkitt, Esther; Barrett, Martyn

2011-01-01

Children tend to use certain drawing strategies differentially when asked to draw topics with positive and negative emotional characterisations. These effects have however only been established when children are asked to use standard drawing materials. The present study was designed to investigate whether the above pattern of children's response…

Dynamic analysis of bulk-fill composites: Effect of food-simulating liquids.

Science.gov (United States)

Eweis, Ahmed Hesham; Yap, Adrian U-Jin; Yahya, Noor Azlin

2017-10-01

This study investigated the effect of food simulating liquids on visco-elastic properties of bulk-fill restoratives using dynamic mechanical analysis. One conventional composite (Filtek Z350 [FZ]), two bulk-fill composites (Filtek Bulk-fill [FB] and Tetric N Ceram [TN]) and a bulk-fill giomer (Beautifil-Bulk Restorative [BB]) were evaluated. Specimens (12 × 2 × 2mm) were fabricated using customized stainless steel molds. The specimens were light-cured, removed from their molds, finished, measured and randomly divided into six groups. The groups (n = 10) were conditioned in the following mediums for 7 days at 37°C: air (control), artificial saliva (SAGF), distilled water, 0.02N citric acid, heptane, 50% ethanol-water solution. Specimens were assessed using dynamic mechanical testing in flexural three-point bending mode and their respective mediums at 37°C and a frequency range of 0.1-10Hz. The distance between the supports were fixed at 10mm and an axial load of 5N was employed. Data for elastic modulus, viscous modulus and loss tangent were subjected to ANOVA/Tukey's tests at significance level p food-simulating liquids on the visco-elastic properties of bulk-fill composites was material and medium dependent. Copyright © 2017 Elsevier Ltd. All rights reserved.

Bulk substrate porosity verification by applying Monte Carlo modeling and Castaing's formula using energy-dispersive x-rays

Science.gov (United States)

Yung, Lai Chin; Fei, Cheong Choke; Mandeep, Jit Singh; Amin, Nowshad; Lai, Khin Wee

2015-11-01

The leadframe fabrication process normally involves additional thin-metal layer plating on the bulk copper substrate surface for wire bonding purposes. Silver, tin, and copper flakes are commonly adopted as plating materials. It is critical to assess the density of the plated metal layer, and in particular to look for porosity or voids underneath the layer, which may reduce the reliability during high-temperature stress. A fast, reliable inspection technique is needed to assess the porosity or void weakness. To this end, the characteristics of x-rays generated from bulk samples were examined using an energy-dispersive x-ray (EDX) detector to examine the porosity percentage. Monte Carlo modeling was integrated with Castaing's formula to verify the integrity of the experimental data. Samples with different porosity percentages were considered to test the correlation between the intensity of the collected x-ray signal and the material density. To further verify the integrity of the model, conventional cross-sectional samples were also taken to observe the porosity percentage using Image J software measurement. A breakthrough in bulk substrate assessment was achieved by applying EDX for the first time to nonelemental analysis. The experimental data showed that the EDX features were not only useful for elemental analysis, but also applicable to thin-film metal layer thickness measurement and bulk material density determination. A detailed experiment was conducted using EDX to assess the plating metal layer and bulk material porosity.

Organic bulk heterojunction photovoltaic structures: design, morphology and properties

International Nuclear Information System (INIS)

Bulavko, G V; Ishchenko, A A

2014-01-01

Main approaches to the design of organic bulk heterojunction photovoltaic structures are generalized and systematized. Novel photovoltaic materials based on fullerenes, organic dyes and related compounds, graphene, conjugated polymers and dendrimers are considered. The emphasis is placed on correlations between the chemical structure and properties of materials. The effect of morphology of the photoactive layer on the photovoltaic properties of devices is analyzed. Main methods of optimization of the photovoltaic properties are outlined. The bibliography includes 338 references

Effect of tooth brushing on gloss retention and surface roughness of five bulk-fill resin composites.

Science.gov (United States)

O'Neill, Catherine; Kreplak, Laurent; Rueggeberg, Frederick A; Labrie, Daniel; Shimokawa, Carlos Alberto Kenji; Price, Richard Bengt

2018-01-01

To determine the effects of tooth brushing on five bulk-fill resin based composites (RBCs). Ten samples of Filtek Supreme Enamel (control), Filtek One Bulk Fill, Tetric EvoCeram Bulk Fill, SonicFill 2, SDR flow+, and Admira Fusion X-tra were light cured for 20 seconds using the Valo Grand curing light. After 24 hours storage in air at 37°C, specimens were brushed in a random order using Colgate OpticWhite dentifrice and a soft toothbrush. Surface gloss was measured prior to brushing, after 5,000, 10,000 and 15,000 back and forth brushing cycles. Surface roughness was measured after 15,000 brushing cycles using atomic force microscopy (AFM) and selected scanning electron microscope (SEM) images were taken. The data was examined using ANOVA and pair-wise comparisons using Scheffe's post-hoc multiple comparison tests (α = 0.05). Surface gloss decreased and the surface roughness increased after brushing. Two-way ANOVA showed that both the RBC and the number of brushing cycles had a significant negative effect on the gloss. One-way ANOVA showed that the RBC had a significant effect on the roughness after 15,000 brushing cycles. For both gloss and roughness, brushing had the least effect on the nano-filled control and nano-filled bulk-fill RBC, and the greatest negative effect on Admira Fusion X-tra. The SEM images provided visual agreement. There was an excellent linear correlation (R 2  = 0.98) between the logarithm of the gloss and roughness. After brushing, the bulk-fill RBCs were all rougher than the control nano-filled RBC. The nano-filled bulk-fill RBC was the least affected by brushing. Bulk-fill RBCs lose their gloss faster and become rougher than the nanofilled conventional RBC, Filtek Supreme Ultra. The nanofilled bulk-fill RBC was the least affected by tooth brushing. © 2017 Wiley Periodicals, Inc.

Bacterial Hand Contamination and Transfer after Use of Contaminated Bulk-Soap-Refillable Dispensers▿†

Science.gov (United States)

Zapka, Carrie A.; Campbell, Esther J.; Maxwell, Sheri L.; Gerba, Charles P.; Dolan, Michael J.; Arbogast, James W.; Macinga, David R.

2011-01-01

Bulk-soap-refillable dispensers are prone to extrinsic bacterial contamination, and recent studies demonstrated that approximately one in four dispensers in public restrooms are contaminated. The purpose of this study was to quantify bacterial hand contamination and transfer after use of contaminated soap under controlled laboratory and in-use conditions in a community setting. Under laboratory conditions using liquid soap experimentally contaminated with 7.51 log10 CFU/ml of Serratia marcescens, an average of 5.28 log10 CFU remained on each hand after washing, and 2.23 log10 CFU was transferred to an agar surface. In an elementary-school-based field study, Gram-negative bacteria on the hands of students and staff increased by 1.42 log10 CFU per hand (26-fold) after washing with soap from contaminated bulk-soap-refillable dispensers. In contrast, washing with soap from dispensers with sealed refills significantly reduced bacteria on hands by 0.30 log10 CFU per hand (2-fold). Additionally, the mean number of Gram-negative bacteria transferred to surfaces after washing with soap from dispensers with sealed-soap refills (0.06 log10 CFU) was significantly lower than the mean number after washing with contaminated bulk-soap-refillable dispensers (0.74 log10 CFU; P soap (P soap from bulk-soap-refillable dispensers can increase the number of opportunistic pathogens on the hands and may play a role in the transmission of bacteria in public settings. PMID:21421792

On the thermodynamic efficiency of a nickel-based multiferroic thermomagnetic generator: From bulk to atomic scale

Energy Technology Data Exchange (ETDEWEB)

Sandoval, Samuel M., E-mail: samuel.m.sandoval@gmail.com; Sepulveda, Abdon E., E-mail: abdon.sepulveda@gmail.com; Keller, Scott M., E-mail: smkeller@ucla.edu [Department of Mechanical and Aerospace Engineering, University of California, Los Angeles, California 90095 (United States)

2015-04-28

A model is developed to correlate the effects of size on the thermodynamic efficiency for a nickel-based multiferroic thermomagnetic generator device. Three existing models are combined in order to estimate this correlation, they are (1) thermodynamic efficiency relations, (2) a model of ferromagnetic transition behavior, and (3) the bond-order length strength correlation. At the smallest size considered, a monolayer of nickel atoms shows a reduction in Curie temperature from its bulk value of T{sub c,Bulk}=630 K to T{sub c,ML}=240 K. This difference is analytically shown to affect the thermodynamic efficiency values when compared to bulk. Various nickel nanofilms are considered as a working body, such that the combined model predicts relative efficiency values that are comparable to the bulk scale, but operating closer to room-temperature when compared to bulk form. This result is unexpected since the absolute efficiency is shown to increase as a function of decreasing size, this discrepancy is explained as a consequence of Curie point suppression. The combined model is also applied to a hypothetical composite made of separated layers of nickel with distinct thicknesses. This composite material is predicted to spread the ferromagnetic transition across a much larger temperature range as compared to bulk nickel, such that this material may be better suited for different applications; for example, as a sensor or thermal switch. Moreover, this combined model is also shown to give a lower-bound estimate for thermodynamic efficiency, since the actual performance depends on material characterizations that have yet to be determined.

Magnetic levitation force between a superconducting bulk magnet and a permanent magnet

International Nuclear Information System (INIS)

Wang, J J; He, C Y; Meng, L F; Li, C; Han, R S; Gao, Z X

2003-01-01

The current density J(ρ, z) in a disc-shaped superconducting bulk magnet and the magnetic levitation force F SBM z exerted on the superconducting bulk magnet by a cylindrical permanent magnet are calculated from first principles. The effect of the superconducting parameters of the superconducting bulk is taken into account by assuming the voltage-current law E = E c (J/J c ) n and the material law B = μ 0 H. The magnetic levitation force F SBM z is dominated by the remnant current density J' 2 (ρ, z), which is induced by switching off the applied magnetizing field. High critical current density and flux creep exponent may increase the magnetic levitation force F SBM z . Large volume and high aspect ratio of the superconducting bulk can further enhance the magnetic levitation force F SBM z

SWeRF--A method for estimating the relevant fine particle fraction in bulk materials for classification and labelling purposes.

Science.gov (United States)

Pensis, Ingeborg; Luetzenkirchen, Frank; Friede, Bernd

2014-05-01