The high pressure, high temperature sapphire cell was designed to provide users at the Spallation Neutron Source the ability to do in-situ supercritical bulk water studies.

关键词：蓝宝石；中子源；散射；约束

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Carbon-coated magnetite nanoparticles (NPs) were synthetized by the mechanochemical method with hematite as precursor and amorphous carbon as inorganic reductor. After 18 hours of milling in an inert atmosphere, a nanocomposite material of magnetite and carbon was obtained. Structural and magnetic properties of the NPs were investigated by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), energy dispersive X-ray spectroscopy (EDS) and vibrating sample magnetometry. XRD patterns, refined with the Rietveld method, show that magnetite is present in samples milled from 6 hours onward and that after milling for 18 hours and annealing in Ar, the sample contains a single crystalline phase. Magnetization curves for samples with different milling times show saturation magnetization values that range from 34.1 emu/g after 1 h to 78.0 emu/g after 18 h. Coercive fields are about 500 Oe for all samples. TEM studies reveal that the samples are made of amorphous carbon clusters with magnetite NPs of 20 nm. The obtained NPs, associated to electrochemical transducers, show an improved enhancement of the charge transfer for redox processes involving different bioanalytes. Thus, these NPs offer unique properties as a catalyst in biosensing strategies for the electrochemical detection of high-impact markers and the development of theranostics smart-devices for biomedical applications.

关键词：电池；电能；纳米颗粒

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Titanium dioxide has been used as the white pigment since the ancient times.95% of its current usage in industry involves paints, cosmetics, plastics, paper, and food. However, in near future the economic impact of titanium dioxide seems to be controlled by energy related applications mostly. Therefore, this chapter projects a brief outlook on the added value provided by the titanium dioxide structures in new and emerging technologies of the energy sector. The applications focused are: solar fuels, solar cells, fuel cells, Li ion batteries and solid state lighting. In those applications, TiO_2 standouts with its chemical and thermal stability, morphology variety, position of conduction and valance band energy levels, optical properties and cost.

关键词：二氧化钛；新兴能源技术；聚焦

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Magnetic nanoparticles and nanocomposites have been special focus of high research interest due to their high magnetic moment and bio-affinity surface properties and promising applications in nanoscience, nanotechnology and bio-applications. These properties can be obtained by synthesizing various magnetic nanoparticles and core-shell type magnetic nanocomposites. In this research, we synthesized high magnetization superparamagnetic nanoparticles and core-shell nanocomposites by chemical and sonochemical method for using as carriers/labels in bio-sensing purpose. Iron oxide magnetic nanoparticles (NPs) have been synthesized by sonochemical method using inexpensive and non-toxic metal salts as reactants. Transmission electron microscopy (TEM) data demonstrated that the particles were narrow range in size distribution with 11 nm average particle size and spherical in shape. The magnetization curve from vibrating sample magnetometer (VSM) measurement shows that as-synthesized NPs were nearly superparamagnetic in magnetic properties with very low coercivity, and magnetization values were 80 emu/g. Monodisperse magnetite nanocubes with uniform particle size of about 80 nm have been synthesized in aqueous medium by sonochemical method. The magnetic characterization of the NPs reveals saturation magnetization of 91 emu/g at 5 K for as-synthesized sample and 94.8 emu/g for the sample which annealed at the temperature of 600 °C in a vacuum chamber. However, the saturation magnetization has been observed to decrease with further increase in annealing temperature and this has been attributed to the presence of a thin magnetic dead layer at the surface caused by shape anisotropy distortion and broken exchange bonds, and spin canting on the surface of the particles in addition to formation of a small amount of maghemite phase. Highly crystalline and monodisperse cobalt ferrite (CoFe_2O_4) nanoparticles have been synthesized via rapid one-pot sonochemical techniques and without subsequent calcination. The size of CoFe_2O_4 nanoparticle was controlled in the range from 20 to 110 nm based on the solvent medium used in the synthesis process. Furthermore, the evolution from spherical to cubic morphology of cobalt ferrite is achieved by simply changing the solvent medium from aqueous to alcoholic medium. High saturation magnetization (Ms) and high coercivity (Hc) values of 87 emu/g and 1610 Oe, respectively were obtained for the CoFe_2O_4 NPs. For synthesis of core-shell type of silica coated iron oxide magnetic (Fe_3O_4@SiO_2 core-shell) NPs, sono-chemical approach was applied using inexpensive and non-toxic chemicals. TEM data demonstrated that the thickness of silica coating on iron oxide magnetic NPs 10-15 nm in average. The magnetization curve from VSM measurement shows that the magnetization has also been decreased of as synthesized silica coated iron oxide NPs compared to freshly prepared bare iron oxide magnetic NPs, which is also a evidence of synthesizing of Fe_3O_4@SiO_2 core-shell NPs. Besides the synthesis of metal oxide core-shell NPs, high magnetization FeCo nanoparticles with different Fe/Co ratios have been successfully synthesized by surfactant free simple modified polyol method. In this process, polyethylene glycol was used as a solvent media and it has been found to play a key role to act as a reducing agent as well as a stabilizer simultaneously. TEM data suggest that the annealed FeCo nanoparticles are of 50-90 nm in size. The physical Property Measurement System (PPMS) reveals that the Fe_(60)Co_(40) composition among all the samples exhibit highest saturation magnetization of 230.14 emu/g at 5K. In another study, high magnetic monodisperse NiFe NPs with different compositions have been successfully synthesized polyol method. TEM images displayed formation of a thin oxide layer around the nanoparticles, and confirmed by detection of some oxygen element using EDS measurement. The magnetic properties of the synthesized NiFe NPs samples were measured VSM at room temperature, and the saturation magnetization value was found to be iron content dependent.

关键词：纳米粒子；磁性纳米颗粒；纳米复合材料

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Recently, organic-inorganic hybrid nanocomposite materials have been of great interest for their extraordinary performances due to the combination of the advantageous properties of polymers and the size dependent properties of nanocrystals (NCs). Interaction between the polymer matrix and nanocrystalline fillers produces wonderful features, viz. thermal, magnetic, mechanical, electrical and optical properties to these materials. Modern applications require a new design of responsive functional coatings which is capable of changing their properties in a controlled way. However, the synthesis of Ⅱ-Ⅵ nanoparticles into the polymer matrix of its nanocomposites with adjustable sizes and protected from photo-oxidation is a big challenge to the scientific community. It is difficult to synthesize the highly enhanced luminescence in polymers and its semiconductor nanocomposite systems. Luminescence from the polymer embedded Ⅱ-Ⅵ nanoparticles is greatly enhanced and better stability can be achieved from the composite compared to bulk materials. The formation of nanocomposites can be confirmed by photoluminescence (PL) spectroscopy. It is an important technique for determining the optical gap, purity, crystalline quality defects and analysis of the quantum confinement in these nanocomposite materials. In this paper, we have reviewed the present status of Ⅱ-Ⅵ polymer nanocomposites from the photoluminescence studies point of view. We have also shown the results of the PL of these nanocomposite materials and the results will be compared with the reported literature by other groups.

关键词：纳米复合材料；半导体；聚合物；光致发光

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Nanofluids are not only valuable for their enhanced thermal properties - a large international research effort has been directed towards developing nanoparticles and nanofluids with tunable optical properties. Optical sensors, optical filters, solar absorbers, lasers, cancer therapies, and a whole suite of other applications can benefit from nanofluids with controlled optical properties. While there are many solid optical components commercially available, flowing fluid-based (both liquids and gases) systems are superior for transient applications. Optical engineering of nanofluids has been made possible by recent advances in fabrication techniques - enabling tight tolerance, highly reliable production of almost any material in a wide variety of shapes and sizes. In the right dose, the addition of well-designed nanoparticles can alter the optical properties of pure fluids (water, oils, and alcohols) from being transparent to bespoke fluids which are highly absorbing, scattering, or a mixture for any portion of the optical spectrum. Metallic nanoparticles, in particular, display the highly selective phenomenon of plasmon resonance which allows them to be utilized to create fluids which can interact strongly with a small band of light. Thus, the development of a new class of nanofluid-based optofluidic devices represents an emerging trans-disciplinary synthesis between nanotechnology, thermofluids, and optics. As a primer to this field and to encourage research activity in this area, this chapter will describe the state-of-the-art and the requisite theory behind this type of technology.

关键词：纳米流体；光学工程；增强热性能

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Magnetic nanofluids are suspensions of nanometer sized magnetic particles stabilized aginst agglomeration and sedimentation. The uniqueness of magnetic nanofluid is that its properties and the location can be easily controlled by an external magnetic field, which is being exploited for many scientific, industrial, and commercial applications. During the search for superior coolants with better heat transfer efficiencies, it was found that magnetic nanofluids can produce a dramatic thermal conductivity enhancement (＞ 300%) due to the efficient transport of heat through the percolating nanoparticle paths. It has also been demonstrated that the field-induced thermal conductivity enhancement can be precisely and reversibly tuned from a low to very high value by varying the magnetic field strength and its orientation. Since the application of magnetic field enhances not only the thermal conductivity but also the rheological properties of the magnetic nanofluid, they find applications in smart cooling cum damping devices. This chapter summarizes the recent research on thermal conductivity of magnetic nanofluids. The effects of volume fraction, magnetic field strength, nanoparticle size, temperature, base fluid material, aggregation and additives on thermal conductivity of magnetic nanofluids are discussed in detail.

关键词：磁性纳米流体；悬浮液；热导率

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In composites, two or more materials are combined in order to employ their individual virtues while minimizing their deficiencies. In general, these hybrid systems exhibit new chemico-physical characteristics that originate from the cooperative effect of the distinctive properties of the materials used. In its own particular way, the engineering of composite carbon-based materials through decoration with metal NanoParticles (NPs) has proved to be key for the improvement of the intrinsic properties of graphene and Carbon NanoTubes (CNTs). A plethora of methods have been employed for the controlled deposition and immobilization of metal NPs onto the CNT surface. To this end, both physical and chemical approaches have been recently developed; each offering its own strengths and weaknesses, which can then be tailored for specific applications. Here we start with an overview of the main methods used for the synthesis of these hybrid systems, with emphasis on the most meaningful examples described in the literature. Metal NP-CNT composites are highly suitable for a number of practical applications ranging from catalysis to optoelectronics to chemical and bio-sensing. The Chapter reports the main efforts carried out to date to integrate metal NP-CNT composites in high-performance nano-devices. The use of modified CNTs often proved more effective than that of pristine ones; however in some cases decoration with metal NPs leads to no improvement. This Chapter sets out to describe the mechanisms, which improve decorated CNTs or pristine CNTs according to the case involved. We conclude by considering metal filled-CNTs, a special class of metal modified-CNTs. The different approaches to filling CNTs with metal NPs are discussed; we then focus on their use as magnetic probes and microwave absorbing materials.

关键词：金属纳米粒子；碳纳米管复合材料；控制器

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Optical metamaterials are man-made composite materials constructed with nanometer-sized periodic structures containing both dielectric and metal materials. These structures can produce materials with negative index of refraction-a unique material property that does not occur naturally. The theoretical breakthroughs made in this new class of electromagnetic materials are closely linked with progress in developing physics-driven design, novel fabrication, and characterization methods. For the optical waveguiding, a perfect control of the interaction between light and matter has been brought closer by the advances in fabrication of optical metamaterials. The unusual electromagnetic properties of metamaterials are expected to enable a new generation of miniaturized passive and active optical devices based on novel optical waveguides. In developing design strategies and new concepts for such devices, it is paramount that anisotropic properties of metamaterials are considered along with their other material features. Moreover, even the ways in which common devices operate require revisions when ordinary materials in their design are replaced by anisotropic metamaterials. Therefore, these metamaterials provide a route to creating potential devices through artificially engineered structures with negative average relative permittivity and permeability. The electromagnetic response of a metamaterial can be designed to produce desired waveguide properties. One particularly interesting metamaterial device is planar metamaterial waveguide structure that has potentially exciting applications. Properties of metamaterial waveguides when the limitations arise from fabrication techniques and physical principles have been taken into account. A considerable amount of theoretical effort has also been devoted to the analysis of optical propagation through different types of metamaterial structures, including uniaxial dielectrics and indefinite media, metal-dielectric heterostructures and superlattices, as well as strongly anisotropic waveguides. This chapter will give a brief review about perspective and prospective of the metamaterial optical waveguides.

关键词：超材料光波导；光学超材料；纳米尺寸

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Constitutive equations of irreversible deformation, e.g. elastoplastic, viscoelastic and viscoplastic deformations are described in rate forms in which the stress rate and the strain rate are related to each other through the tangent modulus. Therefore, numerical calculations are executed in their incremental forms by the input of load (stress) increment or displacement (deformation) increment, while the time increment is also input in rate-(or time-)dependent constitutive equations, e.g. viscoelastic and viscoplastic ones. The algorithm to pull-back the stress to the yield surface is required for the numerical calculation by the elastoplastic constitutive equations other than the subloading surface model possessing the automatic-controlling function to attract the stress to the yield surface. Numerical calculation by the explicit (or forward Euler) method results in the deviation from the exact solution or fails without convergence in the case that the tangent modulus is not constant, if an incremental step is taken large.

关键词：本构方程弹塑性；切线模量；粘弹性

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