Science.gov (United States)

We report on the single-particle properties of lanthanide-ion doped oxide nanoparticles. We have demonstrated that their size can be accurately determined from their luminosity. The optically determined size distribution is in very good agreement with the distribution obtained from transmission electron microscopy (TEM). We also showed that the photobleaching of these nanoparticles is related to a reduction process and that we can use it to sense in a concentration-dependent manner the presence of an oxidant like H2O2. Finally, we propose a way to perform nanoparticle-protein coupling and to determine the protein-nanoparticle ratio at the single-particle level.

Science.gov (United States)

Spectral and energy luminescence characteristics of R6G dye solutions in ethanol with addition of Ag nanoparticle suspensions in different aggregate states are experimentally investigated. It is demonstrated that incorporation of non-aggregated and aggregated nanoparticles causes the superluminescence thresholds in R6G solutions to decrease. It is established that the optical properties of the laser beam propagation channel are transformed when low-power (20 mW) cw laser radiation passes through the suspension of nanoparticles. This is manifested through the occurrence of a region with enhanced nanoparticle density in the laser beam center, on which diffraction of laser radiation is observed.

Energy Technology Data Exchange (ETDEWEB)

In vitro cytocompatibility and cellular interactions of lauric acid and dextran-coated magnetite nanoparticles were evaluated with two different cell lines (mouse fibroblast and human cervical carcinoma). Lauric acid-coated magnetite nanoparticles were less cytocompatible than dextran-coated magnetite nanoparticles and cellular uptake of lauric acid-coated magnetic nanoparticles was more than that of dextran-coated magnetite nanoparticles. Lesser cytocompatibility and higher uptake of lauric acid-coated magnetite nanoparticles as compared to dextran-coated magnetic nanoparticles may be due to different cellular interactions by coating material. Thus, coating plays an important role in modulation of biocompatibility and cellular interaction of magnetic ...

International Nuclear Information System (INIS)

2010 [1 p.] Germany Repp, Felix El-Miladi, Nouri Hoehl, Christian Jahanbakhsh,

Science.gov (United States)

Magnetic drug targeting, using core-shell magnetic carrier particles loaded with anti-cancer drugs, is an emerging and significant method of cancer treatment. Gold shell-iron core nanoparticles (Fe@Au) were synthesized by the reverse micelle method with aqueous reactants, surfactant, co-surfactant and oil phase. XRD, XPS, TEM and magnetic property measurements were utilized to characterize these core-shell nanoparticles. Magnetic measurements showed that the particles were superparamagnetic at room temperature and that the saturation magnetization decreased with increasing gold concentration. The anti-cancer drug doxorubicin (DOX) was loaded onto these Fe@Au nanoparticle carriers and the drug release profiles showed that upto 25% of adsorbed drug was released in 80 h. It was found that the amine (-NH2) group of DOX binds ...

International Nuclear Information System (INIS)

The paper generalizes some results of the United States/Moldova program on advanced composite organic and semiconductor light emitters. High density exciton system bound to N impurity superlattice grown by modern technologies and GaP:N, GaP:N:Sm nanocrystals distributed in transparent fluorine-containing polymers will be used as the base elements for new generation of optoelectronic devices. The work seeks to expand further the applications of GaP itself through the formation of nanocomposites. Classic and new methods are applied for preparation of GaP:N nanoparticles with the controlled dimensions developed clear quantum confinement effect. The long-term ordered bulk GaP crystals as well as their nanoparticles have been investigated by TEM, XRD, Raman scattering, and luminescent methods. The evolution of the Raman Light Scattering and luminescence spectra is reported from pure and doped GaP single ...

Science.gov (United States)

... metal-oleate complexes. At this point, this method has been reported only for iron nanoparticles [15]. We have demonstrated ...

Energy Technology Data Exchange (ETDEWEB)

Magnetite nanoparticles with high self-heating capacity and low toxicity characteristics are a promising candidate for cancer hyperthermia treatment. In order to achieve minimum dosage to a patient, magnetic nanoparticles with high heating capacity are needed. In addition, the influence of physiological factors on the heat capacity of a material should be investigated in order to determine the feasibility. In this study, magnetite nanoparticles coated with lauric acid were prepared by co-precipitation of Fe{sup 3+}:Fe{sup 2+} in a ratio of 2:1, 5:3, 3:2, and 4:3, and the pH was controlled using NaOH. Structural and magnetization characterization by means of X-ray diffractometry (XRD) and a superconducting quantum interference device (SQUID) revealed that the main species was Fe{sub 3}O{sub 4} and further showed that most of the nanoparticles exhibited ...

International Nuclear Information System (INIS)

High-temperature LiCl-KCl molten salt medium provides an efficient way to produce the paramagnetic Eu(II) ion to be magnetically diluted into a diamagnetic host medium. Eu(II) was formed by a dissolution and an auto-reduction processes in a high-temperature LiCl-KCl eutectic melt at 723 K by using Eu_2O_3 as a starting material. By using EPR and luminescence spectroscopic method, we studied the nature of the magnetically isolated paramagnetic Eu(II) ion diluted in a LiCl-KCl medium. With the aid of these spectroscopic tools, it was found that stable Eu(II) species was formed spontaneously at 723 K under anaerobic conditions. EPR and luminescence spectroscopy provided detailed information regarding the nature of the europium ion in a molten salt.

Science.gov (United States)

The liquid-phase synthesis of metal oxide nanoparticles in organic solvents under exclusion of water is nowadays a well-established alternative to aqueous sol-gel chemistry. In this article, we highlight some of the advantages of these routes based on selected examples. The first part reviews some recent developments in the synthesis of ternary metal oxide nanoparticles by surfactant-free nonaqueous sol-gel routes, followed by the discussion of the morphology-controlled synthesis of lanthanum hydroxide nanoparticles, and the presentation of structural peculiarities of manganese oxide nanoparticles with an ordered Mn vacancy superstructure. These examples show that nonaqueous systems, on the one hand, allow the preparation of compositionally complex oxides, and, on the other hand, make use of the organic components (initially present or formed in situ) in the reaction mixture to tailor the morphology. ...

International Nuclear Information System (INIS)

We demonstrate detection of a single core-shell magnetite-silica nanoparticle (outer diameter #approx#120 nm, moment #approx#10"4#mu#_B) using an Nb dc superconducting quantum interference device (SQUID) with the loop size of 350 nm operational at T < 10 K. The system noise was minimized down to 0.2 #mu##PHI#_0 Hz"-"1"/"2 using a cryogenic SQUID series array pre-amplifier. Initial measurements of an individual magnetic nanoparticle were performed and a clear change of the noise spectra of the nano-SQUID was detected at low frequencies in the presence of the nanoparticle. Similar behaviour was confirmed with an FePt nanoparticle with a larger magnetic moment (diameter #approx#150 nm, moment #approx#10"6#mu#_B). Thus, we demonstrate a magnetic sensor based on a dc nano-SQUID and enabling detection of small moments (potentially down to a few ...

British Library Electronic Table of Contents (United Kingdom)

Upconversion nanoparticles (UCNPs) with unique multi-photon excitation photoluminescence properties have recently been intensively explored as novel contrast agents for low-backgroundbiomedical imaging. In this work, we functionalize UCNPs with a polyethylene glycol (PEG) grafted amphiphilic polymer. The PEGylated UCNPs are loaded with a commonly used chemotherapy molecule, doxorubicin (DOX), by simple physical adsorption via a supramolecular chemistry approach for intracellular drug delivery. The loading and releasing of DOX from UCNPs are controlled by varying pH, with an increased drug dissociation rate in acidic environment, favorable for controlled drug release. Upconversion luminescence (UCL) imaging by a modified laser scanning confocal microscope reveals the time course of intracel...

Energy Technology Data Exchange (ETDEWEB)

A composite film consisting of the mixed-addenda Keggin-type polyoxometalate alpha-K{sub 3}PMo{sub 3}W{sub 9}O{sub 40} (PMo{sub 3}W{sub 9}) and silver nanoparticles (AgNPs) was fabricated on quartz, silicon, and ITO by the layer-by-layer self-assembly method. The regular growth of the multilayer film was monitored by UV-vis spectroscopy, and the morphology was measured by atomic force microscopy (AFM). The multilayer film embedded by AgNPs exhibited the photo-luminescence ascribed to electronic transitions from excited states to d levels of the silver nanoparticles. The composite film also showed electrocatalytic activity towards reduction of NO{sub 2}{sup -}, H{sub 2}O{sub 2}, ClO{sub 3}{sup -}, BrO{sub 3}{sup -}, and IO{sub 3}{sup -} attributed to tungsten-centered and molybdenum-centered redox processes of PMo{sub 3}W{sub 9}.

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Magnetic fluids (MFs), prepared by chemical co-precipitation followed by double layer steric and electrostatic (combined) stabilization of magnetite nanoparticles dispersed in water, are presented. Several combinations of surfactants with different chain lengths (lauric acid (LA), myristic acid (MA), oleic acid (OA) and dodecyl-benzene-sulphonic acid (DBS)) were used, such as LA+LA, MA+MA, LA+DBS, MA+DBS, OA+DBS, OA+OA and DBS+DBS. Static light scattering, transmission electron microscopy, small angle neutron scattering, magnetic and magneto-rheological measurements revealed that MFs with MA+MA or LA+LA biocompatible double layer covered magnetite nanoparticles are the most stable colloidal systems among the investigated samples, and thus suitable for biomedical applications.

British Library Electronic Table of Contents (United Kingdom)

A method for estimating the form of magnetic nanoparticles in composite film structures based on the observation of ferromagnetic resonance phenomenon is offered. Within the model of the effective medium, an explanation is given for experimentally observed concentration and temperature dependences of resonant fields for composite nanosystem (Co45Fe45Z10) f +(Al2O3)100?f .

International Science & Technology Center (ISTC)

Development and Creation of Model Samples of Ecologically Safe Luminescent Lamps

British Library Electronic Table of Contents (United Kingdom)

We propose and demonstrate a facile room-temperature synthetic method for obtaining water-soluble magnetic Fe3O4 nanoparticles (NPs) by combining the in situ synthesis and decomposition of a magnetic polymer hydrogel. The Fe3O4 NPs with average diameters of 6.3-8.3nm were synthesized in a cross-linked polyacrylamide (PAAm) hydrogel by coprecipitating iron ions. The decomposition of the magnetic polymer hydrogel by an aqueous solution of sodium hydroxide led to the transfer of Fe3O4 NPs into the aqueous medium. The NPs can be dispersed stably in water for more than three months. The Fe3O4 NPs were characterized by X-ray photoelectron spectra (XPS), X-ray powder diffraction (XRD), transmission electron microscope (TEM), and Fourier transform infrared spectroscopy (FT-IR). The saturation magn...

Science.gov (United States)

Silver iron oxide nanoparticles of fairly small size (average diameter approximately 1 nm) with narrow size distribution have been synthesized by the interaction of colloidal beta- Fe2O3 and silver nanoparticles. The surface morphology and size of these particles have been analyzed by using atomic force microscopy (AFM), field emission scanning electron microscopy (FESEM) and transmission electron microscopy (TEM). Their structural analysis has been carried out by employing x-ray diffraction (XRD), selected-area electron diffraction (SAED), optical and infrared (IR) spectroscopic techniques. The ageing of these particles exhibits the formation of self-assembly, possibly involving weak supramolecular interactions between Ag(I)O4 and Fe(III)O4 species. These particles display the onset of absorption in the near-infrared region and have higher absorption coefficient in the visible range compared to that of its precursors. ...

Energy Technology Data Exchange (ETDEWEB)

Superparamagnetic MFe{sub 2}{sup 3+}O{sub 4} (M=Mn{sup 2+}, Fe{sup 2+} and Co{sup 2+}) inverse spinel ferrite (ISF) nanoparticles with narrow size distribution having average diameters of 6-8 nm were synthesized by a diol reduction of organic metals and the surface was modified to be hydrophilic by coating with succimer. Magnetic resonance imaging (MRI) contrast enhancement by dipolar coupling defined interactions between the synthesized ISFs and protons in the bulk water was investigated with initial susceptibility, magnetization and anisotropy of the succimer-coated ISFs. The relaxivity ratios, r{sub 2}/r{sub 1}, for MnFe{sub 2}O{sub 4}, Fe{sub 3}O{sub 4} and CoFe{sub 2}O{sub 4} were measured to be 12.2, 23.1 and 62.3, respectively, which demonstrate the potential usefulness of these magnetic nanoparticles as T{sub 2} contrast agents for MRI.

Science.gov (United States)

Not Available

International Nuclear Information System (INIS)

The process of miniemulsification allows the generation of small, homogeneous, and stable droplets containing monomer or polymer precursors and magnetite which are then transferred by polymer reactions to the final polymer latexes, keeping their particular identity without serious exchange kinetics involved. It is shown that the miniemulsion process can excellently be used for the formulation of polymer-coated magnetic nanoparticles which can further be used for biomedical applications. The use of high shear, appropriate surfactants, and the addition of a hydrophobe in order to suppress the influence of Ostwald ripening are key factors for the formation of the small and stable droplets in miniemulsion and will be discussed. Two different approaches based on miniemulsion processes for the encapsulation of magnetite into polymer particles will be presented in detail.

British Library Electronic Table of Contents (United Kingdom)

In this paper we demonstrate the electrodeposition of nickel, a common ferromagnetic material, in various magnetically desirable shapes including nanowires, nanoparticles and highly faceted shells. In order to obtain three dimensional mesostructures, the electrochemical deposition of nickel was performed on highly oriented pyrolytic graphite (HOPG) under different electrolyte composition and deposition potential conditions. Under potentiostatic deposition at one distinct potential negative with respect to the reversible potential of nickel, three stages of nucleation and growth take place leading to a complex morphology of deposits. However, dual-pulse potential deposition and electrodeposition in low pH solutions causing hydrogen evolution, lead to nickel deposits in the form of nanowires...

Energy Technology Data Exchange (ETDEWEB)

Based on their interesting properties, metal nanoparticles show the potential as an analytical tool in electronic (Burmeister et al. 2004), optical (Yguerabide and Yguerabide 1998), and catalytic applications (Liu 2006). Their characteristics depend on the composition, shape, and size of the single particles. These various properties are utilized in many different approaches such as optics, magnetics (Lang et al. 2007), and laser technology (Csaki et al. 2007). We investigated an alternative method for the synthesis of nanoparticles. In this case, an enzyme, horseradish peroxidase, induces a silver deposition and replaces a metal nanoparticle as the reaction seed. Depending on the reaction time, we could obtain particles in a range of few nanometers up to more than 250 nm. For a better understanding of the enzymatic silver deposition process, the silver particles produced by this process were analyzed ...

Science.gov (United States)

Not Available

Energy Technology Data Exchange (ETDEWEB)

Individual nanoscale building blocks exhibit a wide range of size-dependent properties, since their size can be tuned over known characteristic length scales of bulk materials. In the last several years, the possibility of combining different materials in the form of two and three component nanoparticles (NPs) has been extensively explored. Also multi-component materials can be obtained via self-assembly of NPs from their binary colloidal mixtures. These new nanocrystal solids may possess tunable collective properties that originate from interactions between size and composition controlled building blocks. Exchange coupling between neighboring NPs of magnetically soft and hard materials enhances the magnetic energy product of the nanocomposite material. Randomly mixed solids of small and large semiconducting CdSe NPs revealed enhancement of photoluminescence intensity of large semiconductor particles accompanied by ...

Science.gov (United States)

INAA (instrumental neutron activation analysis) analyses have been made of subsamples of each OSL (Optically stimulated luminescence) sample, for dosimetry ...

Energy Technology Data Exchange (ETDEWEB)

A method and apparatus for determining the condition of tissue or otherwise making chemical identifications includes exposing the sample to a light source, and using a synchronous luminescence system to produce a spectrum that can be analyzed for tissue condition.

Energy Technology Data Exchange (ETDEWEB)

The primary objective is to perform a fundamental study of filtration of nanoparticles, and to obtain filtration knowledge necessary to design particle collection devices/systems for nanoparticle processing and for preventing nanoparticle emissions into the environment. The research covered a wide area relevant to nanoparticle filtration, under these main topics: (1) nanoparticle filtration and molecular dynamics simulation, (2) nanoparticle virtual impactor, (3) particle transport under low pressure, and (4) development of a high-throughput nanoparticle generator. A number of novel tools and numerical models have been developed under the DOE support.

Energy Technology Data Exchange (ETDEWEB)

A method for the quantitative determination of atmospheric hydroperoxyl radical comprising: (a) contacting a liquid phase atmospheric sample with a chemiluminescent compound which luminesces on contact with hydroperoxyl radical; (b) determining luminescence intensity from the liquid phase atmospheric sample; and (c) comparing said luminescence intensity from the liquid phase atmospheric sample to a standard luminescence intensity for hydroperoxyl radical. An apparatus for automating the method is also included.

International Nuclear Information System (INIS)

... excessive. Due to the response being too weak, attempts to use Infrared

Environmental Research Database

ObjectivesThe development of novel formulations of nanoparticles in the nanotechnology industry and their increasing importance and use in industry means there is certainty of human environmental exposures in both the workplace and the general environment. The pulmonary route of exposure to airborne nanoparticles is a major one, as nanoparticles are handled in industry, escape from workplaces and products containing nanoparticles undergo attrition in the environment. There is a substantial problem for ris [continued...]DescriptionNanoparticles are extremely small particles, each individual particlel being less than one ten millionth of a metre in size. We are exposed to nanoparticles in busy streets as they are present in traffic exhaust produced from combustion of fuel and such nanoparticles are considered to be important in causing the ...

Science.gov (United States)

Besides the multifunctionality, another equally important aspect of nanoparticles is their engineerability to control the geometrical and chemical properties during fabrication. In this work, we exploited this aspect to define asymmetric surface chemistry of an iron oxide nanosphere by controlling the topology of ligand expression on its surface resulting in a particle with two faces, one displaying only amines and the other only thiols. Specifically, amine-functionalized iron oxide nanospheres were attached on a solid support via a crosslinker containing a disulfide bridge. Liberation of the nanosphere using thiolytic cleavage created thiols on the portion of the particle's surface that interacted with the solid support. Employing a solid-phase strategy and a step-by-step addition of particles, the two unique faces on the same nanosphere served as fittings to assemble them into linear nano-chains. Assembly of chains with various lengths and aspect ratios was ...

CERN Document Server

Preparation of covalently modified organic-inorganic composite nanoparticles and their interfacial electron transfer researches

British Library Electronic Table of Contents (United Kingdom)

Based on the corrected phase diagrams proper growth conditions for Li2Zn2(MoO4)3 crystals are selected. Large crystals (up to 100 mm), both impurity-free and activated by transition metal ions (Cu, Cr), are grown by the low-gradient Czochralski method. By the EPR method the charge state and structural position of copper and chromium ions are determined. The performed studies of luminescent properties show that for impurity-free crystals luminescence with ? = 388 nm with a two-exponential luminescence decay with ?1 = 2 ns and ?2 = 6 ns is observed at room temperature. At 77 K for both impurity-free crystals and those activated with transition metal ions luminescence with ? = 560 nm and the luminescence lifetime ? = 100 ns is observed, the intensity of luminescence with ? = 560 nm depending ...

British Library Electronic Table of Contents (United Kingdom)

The 1H NMR, electronic absorption, and luminescence spectra, as well as voltammograms of the reduction and oxidation of the complexes [Pd(C?N)(N?N)]ClO4 and [Pd(C?N)(?-OOCCH3)]2 [where (C?N)? is deprotonated 2-phenyl-4,5-dihydro-1,3-oxazole, and N?N is ethylenediamine or 2,2?-bipyridine (bpy)] were compared. Magnetic nonequivalence of protons in the dihydrooxazole ring and upfield shift of the corresponding signals were observed as a result of anisotropic effect of the ring current in palladated phenyl substituents in the [Pd(C?N)(?-OOCCH3)]2 complex having a C 2 symmetry. One-electron reduction wave of [Pd(C?N)bpy]+ was assigned to ligand-centered electron transfer to the ?* orbital of 2,2?-bipyridine, and two oxidation waves of [Pd(C?N)(?-OOCCH3)]2 were attributed to successive one-elect...

Science.gov (United States)

We show that the size of a lanthanide-ion doped nanoparticle can be accurately determined from its luminosity. The optically determined size distribution is in very good agreement with the distribution obtained from transmission electron microscopy. These data confirm that single nanoparticles are visualized in microscopy experiments. Nanoparticles as small as 13 nm are detectable with integration times of 500 ms.

DEFF Research Database (Denmark)

Udgivelsesdato: 2008/5

Energy Technology Data Exchange (ETDEWEB)

No abstract prepared.

Science.gov (United States)

The progress in the development of a surface analysis tool based on the excitation of characteristic

International Nuclear Information System (INIS)

The results of the study of dimensionally dependent fluorescence of boron difluoride ?-diketonates of general formula (R1COCHCOR2)BF2 are presented. The fact that for most of the compounds studied a noticeable hypsochrome shift of the luminescence band maximum is characteristic during transition from bulk crystals to microcrystals was detected. However, for boron difluoride dibenzoylmethanate having a unique supramolecular structure, a bathochromic shift of luminescence due to the crustal size reduction is observed. The dimensionally dependent luminescence properties of the complexes have been analyzed within the exciton mechanism

Energy Technology Data Exchange (ETDEWEB)

The differences are highlighted of various aspects of behaviour of the luminescence signal from feldspar when stimulated by green light and when stimulated by infrared radiation. In respect of bleaching, a comparison is made of the influence of white light (daylight) on the two stimulated luminescence signals, as well as a comparison of the influence of infrared exposure on the green-stimulated signal with the influence of green exposure on the infrared-stimulated signal. The influence of preheating on the two stimulated signals is also compared. Light-emitting diode systems were used for both green and infrared stimulation. The observations are considered in relation to the mechanism relevant to green- and infrared-stimulated luminescence from feldspar. (author).

Energy Technology Data Exchange (ETDEWEB)

This invention relates to new phosphor materials and to combinatorial methods of synthesizing and detecting the same. In addition, methods of using phosphors to generate luminescence are also disclosed.

Energy Technology Data Exchange (ETDEWEB)

We report a simple method for the label-free detection of double-stranded DNA using surface-enhanced Raman scattering (SERS). We prepared cetyltrimethylammonium bromide (CTAB)-capped silver nanoparticles and a DNA-nanoparticle complex by adding silver nanoparticles to {lambda}-DNA solutions. In the present study, the utilization of CTAB-capped silver nanoparticles facilitates the electrostatic interaction between DNA molecules and silver nanoparticles; at the same time, the introduction of DNA avoids adding aggregating agent for the formation of nanoparticle aggregates to obtain large enhancement of DNA, because the DNA acts as both the probe molecules and aggregating agent of Ag nanoparticles. Atomic force microscopy (AFM) studies show that the morphology of DNA-Ag nanoparticle complexes seems to be determined by the ...

Energy Technology Data Exchange (ETDEWEB)

Luminescence stimulated from feldspars using wavelengths in the infrared region can be applied to the dating of sedimentary grains. Reported stimulation spectra are very similar for a wide range of feldspars, but their emission spectra show greater variation. For accurate dating it is critical that unstable infrared-stimulated luminescence (IRSL) signals are removed from the laboratory-irradiated grains. Several approaches to isolate a thermally stable signal are described. (author).

Energy Technology Data Exchange (ETDEWEB)

Ion Beam Induced Luminescence (IBIL) and Ion Beam Induced Charge Collection (IBICC) have been applied in the study of the luminescence emission efficiency and investigation of the homogeneity of the luminescence emission in phosphors. The IBIL imaging was performed by using sharply focused ion beams or broad/partially-focused ion beams. The luminescence emission homogeneity in samples was examined to reveal possible distributed crystal-defects that may lead to the inhomogeneity of the luminescence emission in samples.The purpose of the study is to search for suitable luminescent thin films that have high homogeneity of luminescence emission, large IBIL efficiency under heavy ion excitation, and can be placed as a thin layer on the top of microelectronic devices to be analyzed with Ion Photon Emission Microscopy (IPEM). The emission yield was ...

International Nuclear Information System (INIS)

Palladium/magnetite nanoparticulate catalysts were developed for efficient elimination of halogenated organic pollutants from contaminated wastewater. Particle recovery from treated water can be ensured via magnetic separation. However, in worst-case scenarios, this catalyst removal step might fail, leading to particle release into the environment. Therefore, a toxicological study was conducted to investigate the impact of both pure magnetite and palladium/magnetite nanoparticle exposure upon human skin (HaCaT) and human colon (CaCo-2) cell lines and a cell line from rainbow trout gills (RTgill-W1). To quantify cell viability after particle exposure, three endpoints were examined for all tested cell lines. Additionally, the formation of reactive oxygen species was studied for the human cells. The results showed only minor effects of the particles on the tested cell systems and support the assumption that palladium/magnetite nano-catalysts can ...

British Library Electronic Table of Contents (United Kingdom)

A magnetic core/shell Fe3O4/FeMnOx catalyst was prepared by a simple oxidation-precipitation method. The catalyst was characterized by X-ray diffraction, transmission electron microscope, X-ray photoelectron spectroscopy, Fourier transform infrared spectroscopy, thermogravimetric analysis and cyclic voltammetry. The characterization studies verified that Fe3O4 core was coated with a layer of Fe-Mn oxide. The Fe3O4/FeMnOx was found to be an effective and stable heterogeneous catalyst for the discoloration of methylene blue (MB) in aqueous solution by H2O2. The high catalytic activity is due to the FeMnOx shell, which not only increased the surface hydroxyl groups, but also enhanced the interfacial electron transfer. The discoloration of MB could be due to the decomposition of H2O2 into ?OH ...

International Nuclear Information System (INIS)

... range magnetic fields magnetic susceptibility magnetization neutron diffraction

International Nuclear Information System (INIS)

Inorganic nanoparticles are indispensable for science and technology as materials, pigments and cosmetics products. Improving the dispersion stability of nanoparticles in various liquids is essential for those applications. In this review, we discuss why it is difficult to control the stability of nanoparticles in liquids. We also overview the role of surface interaction between nanoparticles in their dispersion and characterization, e.g. by colloid probe atomic force microscopy (CP-AFM). Two types of surface modification concepts, post-synthesis and in situ modification, were investigated in many previous studies. Here, we focus on post-synthesis modification using adsorption of various kinds of polymer dispersants and surfactants on the particle surface, as well as surface chemical reactions of silane coupling agents. We discuss CP-AFM as a technique to analyze the surface interaction between ...

Energy Technology Data Exchange (ETDEWEB)

The photoluminescence intensity of an optical emitter changes when placed in close proximity to a noble-metal nanoparticle, due to two contributions. First, the optical near-field of the nanoparticle leads to a change in excitation rate of the emitter. Secondly, the emission efficiency is changed due to an optical energy transfer from the emitter to the metal nanoparticle, which provides additional radiative and non-radiative decay channels. In this work we investigate the photoluminescence of Sm{sup 3+} ions, which are embedded in SiO{sub 2}. The photoluminescence spectrum of ions in proximity to single silver and gold nanoparticles is measured. The influence of the spectral position of the nanoparticle plasmon peak on the photoluminescence yield will be discussed and compared with model calculations.

British Library Electronic Table of Contents (United Kingdom)

In situ synthesis of silver chloride (AgCl) nanoparticles was carried out under ambient conditions in nanoporous bacterial cellulose (BC) membranes as nanoreactors. The growth of the nanoparticles was readily obtained by alternating dipping of BC membranes in the solution of silver nitrate or sodium chloride followed by a rinse step. X-ray diffraction (XRD) patterns indicated the existence of AgCl nanoparticles in the BC and scanning electron microscopy (SEM) images showed that the AgCl nanoparticles well dispersed on the surface of BC and penetrated into the BC network. The AgCl nanoparticle-impregnated BC membranes exhibited high hydrophilic ability and strong antimicrobial activity against Escherichia coli (Gram-negative) and Staphylococcus aureus (Gram-positive). The preparative proced...

International Nuclear Information System (INIS)

Full text of publication follows: Understanding the dynamic irradiation effects on silica glasses is important for developing the diagnostic systems used in fusion and fission environments. While fundamental defects having an un-pared electron such as the E' center have been extensively studied, the neutral oxygen deficiency defects have been insufficiently clarified for lack of the detection methods. The ion induced luminescence is one of the probes that can be used to detect non-paramagnetic defects, and to observe creation and annihilation behavior dynamically. In the present study, we examined the characteristics of the ion induced luminescence such as energy, fluence flux and temperature dependence of the luminescence efficiency to analyze damage process quantitatively. Samples of SiO2 glasses were commercially available fused and synthesized silica glasses, produced by Toshiba Ceramics, Co. Ltd.. A thin films of SiO2 ...

UK PubMed Central (United Kingdom)

This work describes the synthesis and characterization of novel thermoresponsive highly-branched polyamidoamine-polyethylene glycol-poly (D, L-lactide) (PAMAM-PEG-PDLLA) core-shell nanoparticles....Full Text Available

UK PubMed Central (United Kingdom)

BackgroundSilica nanoparticles (SiNPs) are being formulated for cellular imaging and for nonviral gene delivery in the central nervous system (CNS), but it is unclear what potential...Full Text Available

British Library Electronic Table of Contents (United Kingdom)

Rheological properties of moderately concentrated solutions of cellulose in methylmorpholine N-oxide-dimethylformamide mixtures containing hydrophilic montmorillonite nanoparticles were studied. Film composite materials were prepared, and their physicomechanical properties and structural organization were studied.

KoreaScience (Korea)

Full Text Available

Energy Technology Data Exchange (ETDEWEB)

The purpose of this study is fabrication and characterization of silver nanofluid by the submerged arc nanoparticle synthesis system (SANSS). The silver metal electrodes under the electrical discharge will melt and evaporate rapidly and condense to form the nanoparticles in the lower temperature dielectric liquid and produce the suspended nanoparticle. The results showed that the spherical nanosilver particle formed in the ethylene glycol and the mean particle size is about 12.5 nm. The prepared silver nanofluid was irradiated under the 410 nm visible light, electrons could be excited from the valence band to the conduction band. The silver nanofluid more closely resembles Newtonian fluids.

Science.gov (United States)

The sunlight-induced photocatalytic oxidation of aqueous benzene on TiO(2)-supported gold nanoparticles was considerably improved when the reaction was conducted under a CO(2) atmosphere. 13% yield and 89% selectivity of phenol was obtained on P25-supported gold nanoparticles under 230 kPa of CO(2). PMID:21952312

International Nuclear Information System (INIS)

The results of studies of the time-resolved luminescence of self-trapped excitons (STE) with different multiplicity as well as the X-ray emission in oriented BeO crystals under excitation in the vicinity of the 1 s Be photoabsorption edge are presented. The branching of the electronic excitations relaxation depends strongly on the crystal orientation after the inner-shell excitation. The common features between the processes of the STE luminescence and resonantly excited X-ray fluorescence have been discussed.

International Nuclear Information System (INIS)

The intensity of erbium up-conversion luminescence could be limited by a saturation effect due to increased pump power. We studied the luminescence saturation of the 550 nm emission on erbium-doped, SiO_2-TiO_2 sol-gel powders under pulsed excitation at 979 and 1532 nm. From the latter, the up-converted luminescence intensity decreased with increasing excitation power, whereas no saturation was observed at 979 nm excitation. We proposed that the saturation effect is determined by the pump power, the erbium content and the lifetime of the corresponding first excited states at different pumping schemes.

Science.gov (United States)

Not Available

British Library Electronic Table of Contents (United Kingdom)

An aliphatic thiol ligand of CuInS2/ZnS core/shell quantum dots is replaced with a hydroxyl-terminated thiol ligand by utilizing `on-off state' of ligands during growth stage of the quantum dots. After the ligand-exchange, negligible differences were observed on both photoluminescence spectrum and luminescent quantum efficiency. The reason for the high retention of luminescent efficiency comes from no local agglomeration and no surface deterioration of QDs. It is also observed that 70% of initial ligands are exchanged by the replacing ligand, determined by FT-IR and 1H NMR. The proposed method provides the quantum dots with an excellent dispersibility in polar solvents, supported by identical luminescence decay characteristics of the QDs.

Energy Technology Data Exchange (ETDEWEB)

In this paper we describe a fractal assembly of copper nanoparticles on different substrates by controlling the chemical replacement reaction. Through calculation, we found that the 'fractal dimensions' of copper dendrites synthesized by us were about 1.832, which agreed well with the 'fractal dimensions' of natural fern leaves (fractal dimension, 1.826), suggesting that the fern fractal model was useful to describe the self-assembly of our copper nanoparticles during the chemical replacement reaction process. These results will be beneficial for the understanding of the role that highly nonequilibrium conditions play in the formation of fractal clusters as well as the self-assembly mystique of metallic nanoparticles in nonequilibrium conditions and also helpful in the future assembly of complicated nanoarchitectures of metallic nanoparticles for potential ...

British Library Electronic Table of Contents (United Kingdom)

The growth of silver chloride nanoparticles on ancient textile was achieved by sequential dipping steps in alternating bath of potassium chloride and silver nitrate under ultrasound irradiation. The effect of ultrasound irradiation and sequential dipping steps in growth of the AgCl nanoparticles has been studied. These systems depicted a decrease in the particles size accompanying a decrease in the sequential dipping steps. The samples were characterized with powder X-ray diffraction (XRD) and scanning electron microscopy. XRD analyses indicated that the prepared AgCl nanoparticles on fiber were crystalline. The textile samples containing AgCl nanoparticles were tested for their antibacterial efficacy against Escherichia coli and were found to possess significant antibacterial activity.

Energy Technology Data Exchange (ETDEWEB)

We demonstrate that the nanoparticle formation during laser ablation of metals by short (of a few tens of ps) laser pulses strongly depends on the concentration of surrounding gas. While, at vacuum conditions, nanoparticle formation shows very ''sharp'' atomic force microscope images of aggregated clusters, following with clear appearance of plasmon resonance on the absorption spectra of deposited films, an addition of gas particles starts to decrease the probability of cluster formation. This process shows a threshold for both helium (33 torr) and xenon (12 torr) above which no surface plasmon resonance and correspondingly no observable nanoparticles on the deposited surfaces were detected. The destruction of nanoparticle formation was attributed to the negative influence of surrounding gas particles on ablated particles aggregation. (orig.)

International Nuclear Information System (INIS)

We described the use of silica nanoparticles as building blocks for the immobilization of electrogenerated chemiluminescence (ECL) reagent Ru(bpy)_3"2"+ and the fabrication of layer-by-layer assembly film by alternating the deposition of the Ru(bpy)_3"2"+-doped silica nanoparticles and Au nanoparticles. UV-vis absorption spectroscopy, scanning electron microscopy (SEM), cyclic voltammetry and ECL were used to characterize the uniform growth of the multilayer film. Since Ru(bpy)_3"2"+ could still maintain its ECL property when doped into the silica nanoparticles, the as-prepared multilayer film could be used as an effective ECL sensor, and the sensor showed high sensitivity and good stability.

British Library Electronic Table of Contents (United Kingdom)

Gold nanoparticles were synthesized by using banana peel extract (BPE) as a simple, non-toxic, eco-friendly 'green material'. The boiled, crushed, acetone precipitated, air-dried peel powder was used to reduce chloroauric acid. A variety of nanoparticles were formed when the reaction conditions were altered with respect to pH, BPE content, chloroauric acid concentration and temperature of incubation. The reaction mixtures displayed vivid colors and UV-vis spectra characteristic of gold nanoparticles. Dynamic light scattering (DLS) studies revealed that the average size of the nanoparticles under standard synthetic conditions was around 300nm. Scanning electron microscopy and energy dispersive spectrometry (EDS) confirmed these results. A coffee ring phenomenon, led to the aggregation of th...

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Size-selected SnO{sub 1.8}:Ag mixed nanoparticle films have been prepared using a gas phase condensation method. Transmission electron microscopy showed that the applied size-selection technique yields well-defined, monodisperse and spherical SnO{sub 1.8} and Ag nanoparticles, both with a fixed diameter of 20 nm. The technique allows an independent variation of the particle size of both materials as well as the concentration of Ag. It allows to assess the influence of these parameters on the gas-sensing properties of the films, here for ethanol vapor in synthetic air. SnO{sub 1.8}:Ag nanoparticle films show optimal values of the sensor signal and response time at a Ag nanoparticle concentration of 5%. Due to the fact that the Ag nanoparticles are clearly distinct from the SnO{sub 1.8} nanoparticles in the film, the most probable mechanism leading to improved ...

CERN Document Server

The Rayleigh scattering length has been calculated for rare-gas liquids in the ultraviolet for the frequencies at which they luminesce. The calculations are based on the measured dielectric constants in the gas phase, except in the case of xenon for which measurements are available in the liquid. The scattering length mayplace constraints on the design of some large-scale detectors, using uv luminescence, being proposed to observe solar neutrinos and dark matter. Rayleigh scattering in mixtures of rare-gas mixtures is also discussed.

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A series of OSL properties of fragments from split feldspar grains have been investigated. These are (1) the response to a radiation dose, (2) the recycling of corrected induced luminescence (L{sub i}/T{sub i}), (3) the corrected natural luminescence (L{sub N}/T{sub N}), (4) the corrected thermal transfer luminescence (termed herein L{sub tt}/T{sub tt}) and, (5) the rate of anomalous fading ('g'). It was found that the parameters of different parts of the same grain are the same. The relative uncertainty, at the 2 sigma level, at which we can claim that the measured parameters are correlated, is generally less than 5% but is ca 40% for the anomalous fading rate due to measurement uncertainty. For young partially bleached sediments, the result is that one could use one fragment to evaluate the equivalent dose and another to assess the contribution of thermal transfer resulting from preheating the natural ...

International Nuclear Information System (INIS)

We used the recuperation effect (see also 'Recuperation of infrared stimulated luminescence of feldspars' in this issue) for investigating the connection between infrared- and greenlight-stimulated luminescence (IRSL and GLSL) of feldspars by performing a 'double-bleach recuperation' experiment. A diode system was used for infrared (IR) stimulation, and a filtered-light unit for greenlight (GL) stimulation. Powdered feldspar samples (2 mg each) of known chemical characterisation from a mineral collection were used. After beta-irradiation with 180 Gy and storage in the dark for several weeks feldspar aliquots were bleached down to a residual level of #approx#1% of the initial level, first with IR and subsequently with GL. For both stimulations, detection of the stimulated luminescence was carried out in the near ultraviolet region (around 260-360 nm, peaked at 340 nm). Other aliquots were bleached in reverse order (1st GL, ...

UK PubMed Central (United Kingdom)

Diamagnetic samples placed in a strong magnetic field and a magnetic field gradient experience a magnetic force. Stable magnetic levitation occurs when the magnetic force exactly counter balances...Full Text Available

Energy Technology Data Exchange (ETDEWEB)

Studying the structure of nanoparticles as a function of their size requires a correlation between the image and the diffraction pattern of single nanoparticles. Nanobeam diffraction technique is generally used but requires long and tedious TEM investigations, particularly when nanoparticles are randomly oriented on an amorphous substrate. We bring a new development to this structural study by controlling the nanoprobe of the Bright and Dark Field STEM (BF/DF STEM) modes of the TEM. The particularity of our experiment is to make the STEM nanoprobe parallel (probe size 1 nm and convergence angle <1 mrad) using a fine tuning of the focal lengths of the microscope illumination lenses. The accurate control of the beam position offered by this technique allowed us to obtain diffraction patterns of many single nanoparticles selected in the digital STEM image. By means of this technique, we demonstrate ...

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Nanoparticles of AgBr were prepared by precipitating AgBr in the water pools of microemulsions consisting of CTAB, n-butanol, isooctane and water. An aqueous solution of AgNO{sub 3} added to the microemulsion was the source of Ag{sup +} ions. The formation of AgBr nanoparticles in microemulsions through direct reaction with the surfactant counterion is a novel approach aimed at decreasing the role of intermicellar nucleation on nanoparticle formation for rapid reactions. The availability of the surfactant counterion in every reverse micelle and the rapidity of the reaction with the counterion trigger nucleation within individual reverse micelles. The effect of the following variables on the particle size and size distribution was investigated: the surfactant and cosurfactant concentrations, moles of AgNO{sub 3} added, and water to surfactant mole ratio, R. High concentration of the surfactant or cosurfactant, or high water ...

International Nuclear Information System (INIS)

Nanoporous materials have become indispensable in many fields ranging from photonics, catalysis and semiconductor processing to biosensor infrastructure. Rapid and energy efficient process fabrication of these materials is, however, nontrivial. In this communication, we describe a simple method for the rapid fabrication of these materials from colloidal dispersions of Polymethyl Silsesquioxane nanoparticles. Nanoparticle-polymer composites above the decomposition temperature of the polymer are examined and the entropic gain experienced by the nanoparticles in this rubric is harnessed to fabricate novel highly porous films composed of nanoparticles. Optically smooth, hydrophobic films with low refractive indices (as low as 1.048) and high surface areas (as high as 1325 m2 g-1) have been achieved with this approach. In this communication we address the behavior of such systems that are both temperature ...

International Nuclear Information System (INIS)

Using stoichiometrically controlled 1:1 functionalization of gold nanoparticles with fluorescent dye molecules in which the dye molecule is held away from the particle surface by a rigid DNA spacer allows precise determination of the distance-dependent effect of the metal nanoparticles on fluorescence intensity. Two dyes were studied, Cy3 and Cy5, with two sizes of nanoparticles, 5 and 10 nm. The larger the particle, the more quenching of the photoluminescence (PL) intensity, due to increased overlap of the dye's emission spectrum with the Au surface plasmon resonance. Fluorescence is quenched significantly for distances somewhat larger than the particle diameter, in good agreement with the predictions of an electrodynamics model based on interacting dipoles. The distance dependence of surface energy transfer behavior, i.e. quenching efficiency, is proportional to 1/d4, which involves no consideration of the size of the ...

Energy Technology Data Exchange (ETDEWEB)

No abstract prepared.

Science.gov (United States)

in pulse applications such as magnetic forming. ... In magnetic-forming electric circuitry, the ..... Aspects of Electrohydraulic land Magnetic Forming. ...

Energy Technology Data Exchange (ETDEWEB)

We demonstrate the rapid optical characterization of large numbers of individual metal nanoparticles freely diffusing in colloidal solution by confocal laser spectroscopy. We find that hollow gold nanospheres and solid silver nanoparticles linked with a bifunctional ligand, both designed nanostructures, exhibit significantly higher monodispersity in their Rayleigh and Raman scattering response than randomly aggregated gold and silver nanoparticles. We show that measurements of rotational diffusion timescales allow sizing of particles significantly more reliably than can be obtained using translational diffusion timescales.

International Nuclear Information System (INIS)

A nanoparticle generator based on the principle of electrical discharge (PALAS GFG-1000) was used to produce nanoparticles of different chemical natures. The fractions of electrically neutral particles were then measured by means of a Spectrometre de Mobilite Electrique Circulaire (SMEC, i.e. radial-flow mobility analyzer) for different operating conditions. The experimental results were compared with the theoretical values calculated from the Fuchs extended charge equilibrium model for spherical particles and agglomerates. For the smallest particles (below 20 nm), the deviations observed remain below 10%, and tend towards 20% for larger particles (over 35 nm).

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The variation of surface composition and sintering of the binary Pd{sub 7}Ag{sub 3} nanoparticles prepared by chemical reduction were studied. The composition of the as-prepared Pd{sub 7}Ag{sub 3} nanoparticles across the diameter is inhomogeneous due to different reduction potentials of Pd and Ag. Upon heating, Ag will migrate to the surface because of its lower surface energy. Surface modification results in variation of surface composition during the sintering process. Stearic acid acts as a grain growth inhibitor. The migration of Ag to the surface is suppressed and the sintering is retarded. Modification by polyethylene glycol leads to more migration of Ag atoms from the core to the surface. This makes the nanoparticles easier to sinter.

British Library Electronic Table of Contents (United Kingdom)

Highly dispersed silver nanoparticles embedded in mesoporous thin films (MTFs) have been synthesized by modification of the interior surface of mesoporous silica with ethylenediamine moieties, which provided the coordination sites for the Ag ions, and subsequent reduction under hydrogen atmosphere. TEM observations show the mesoporous parent films have effectively controlled the growth of the synthesized silver nanoparticles. The composite films had an ultrafast nonlinear response time, as fast as 200 fs, and a third-order nonlinear optical susceptibility of 0.94??10?10 esu, which was enhanced by the local field enhancement effect that was present when the silver nanoparticles were embedded in the surrounding dielectric matrix. The origin of the ultrafast nonlinear response and the enhanc...

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Metallic nanoparticles was synthesized in SiO{sub 2} matrices by means of a process of two stages. The first one proceeded via sol-gel, incorporating the metallic precursors to the reaction system before the solidification of the matrix. Later on, the samples underwent a thermal treatment in atmosphere of H{sub 2}, carrying out the reduction of the metals that finally formed to the nanoparticles. Then it was detected the presence of smaller nanoparticles than 20 nm, dispersed and with the property of being liberated easily of the matrix, conserving a free surface, chemically reactive and with response to external electromagnetic radiation. The system SiO{sub 2}-Pd showed an important thermoluminescent response. (Author)

British Library Electronic Table of Contents (United Kingdom)

Size-controllable Ag nanoparticle ultrathin films, which were fabricated by vacuum deposition method from high purity Ag wire onto cleaned indium tin oxide conducting glass, have different color fabricated by variation of preparation conditions. The UV/Vis spectra showed that optical absorption peak of these Ag nanoparticle films can be tuned in a range from 457nm to >650nm. Scanning electron microscopy images showed that with increasing film thickness Ag particle size was larger. Ag/WO3 composite films were prepared by cathodic electrodeposition of WO3 onto the surface of Ag nanoparticle films. Spectroelectrochemistry and electrochromic properties of the resulting composite films were characterized. It was found that the electrochemical and electrochromatic properties of the composite fil...

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The rapid growth in the use of in vitro methods for nanoparticle toxicity assessment has proceeded with limited consideration of the unique kinetics of these materials in solution. Particles in general and nanoparticles specifically, diffuse, settle and agglomerate in cell culture media as a function of several systemic and particle factors: media density and viscosity, particle size, shape and density. Cellular dose then is also a function of these factors as they determine the rate of transport of nanoparticles to cells in culture. Here we develop and apply the principles of particokinetics and dosimetry in vitro and outline an approach for simulation of nanoparticle particokinetics in cell culture systems. We illustrate that where equal mass concentrations (?g/ml) imply equal doses for dissimilar materials, the corresponding particle number or surface area concentration doses differ by orders of ...

British Library Electronic Table of Contents (United Kingdom)

The addition of ?-Sialon nanoparticles to lubricants in heavy-duty frictional joints is shown to be effective.

Science.gov (United States)

... The MTT assay indicates cell viability through a yellow to purple ... besiegers were said to have catapulted plague infected corpses into the city of ...

British Library Electronic Table of Contents (United Kingdom)

The formation of nanoparticles during the radiation-induced chemical reduction of silver ions, copper ions, and nickel ions in films based on poly(acrylic acid)-poly(ethylenimine) complexes are studied via electron microscopy. This approach allows preparation of composites containing nanoparticles that are randomly distributed in the polymer matrix and materials with a regular spatial distribution of nanoparticles across the film thickness and in subsurface layers. The structure of metal-polymer hybrid materials is dependent on the irradiation conditions, the type of reduced metal ions, and their initial content in polymer matrices. The ratio between the rate of nucleation and the rate of growth of nanoparticles in the matrices of interpolyelectrolyte complexes depends on the intensity of ...

British Library Electronic Table of Contents (United Kingdom)

Emeraldine base (EB) polymer?ZnO nanoparticles composite films has been synthesized by solution casting technique on ITO-coated glass substrate and characterized by XRD, FTIR and TEM for their structure and morphology. Dielectric behaviour of these composite films has been investigated in the very low frequency region to medium frequency region (1?kHz?1?MHz). The dielectric constant of the composite with 30% nanoparticles is almost one-tenth of the pure EB. The dielectric value becomes constant in the frequency region greater than 400?kHz. The change in dielectric behaviour of the composite is explained on the basis of multilayered interface formed between the ZnO nanoparticles and emeraldine chains. Nanoparticles have high energy surface which is responsible for the decrease of free volum...

British Library Electronic Table of Contents (United Kingdom)

Bio-inspired silver nanoparticles were synthesized with the aid of a novel, non-toxic, eco-friendly biological material namely, banana peel extract (BPE). Boiled, crushed, acetone precipitated, air-dried peel powder was used for reducing silver nitrate. Silver nanoparticles were formed when the reaction conditions were altered with respect to pH, BPE content, concentration of silver nitrate and incubation temperature. The colorless reaction mixtures turned brown and displayed UV-visible spectra characteristic of silver nanoparticles. Scanning electron microscope (SEM) observations revealed the predominance of silver nanosized crystallites after short incubation periods. When the reaction mixtures were incubated for 15 days, some micro-aggregates were also observed. Energy dispersive spectr...

International Nuclear Information System (INIS)

Eu"3"+ and Tb"3"+ complexes with novel branched calix[4]arene ligands incorporating 2,2' -bipyridine subunits functionalized in the 6- or 5,5'-positions have been synthesized and their photophysical properties investigated. High luminescence intensity was obtained for the Eu"3"+ complex of the calix[4]arene ligand carrying four 5,5' -substituted- 2,2' -bipyridines, which has high molar extinction coefficients (#epsilon#_m_a_x 39 600 M"-"1 cm"-"1) and a high luminescence quantum yield (15%). (authors). 12 refs., 2 figs., 1 tab.

Energy Technology Data Exchange (ETDEWEB)

A new luminescent europium probe is presented for the determination of phosphate (P) in microtiter plate format. The assay is based on the quenching of the luminescence of the europium-tetracycline (EuTc) 1:1 complex by phosphate using a reagent concentration of 20.8 {mu}mol/L. The probe is excited at 400 nm and displays a large Stokes' shift of 210 nm. The emission maximum is located at 616 nm. The system works best at neutral pH 7 and is therefore suitable for phosphate determination in biological and biochemical systems. The linear range of the calibration plot is from 5 x 10{sup -6} mol/L to 7.5 x 10{sup -4} mol/L of phosphate, and the limit of detection is 3 {mu}mol/L.

Science.gov (United States)

The development of new efficient afterglow phosphors is currently hampered by a limited understanding of the persistent luminescence mechanism. Radioluminescence (RL) and x-ray absorption measurements on the persistent phosphor SrAl2O4:Eu,Dy were combined to reveal possible valence state changes for the rare earth (co)dopants. Traps in the phosphor material are quickly filled when exposing thermally emptied SrAl2O4:Eu,Dy powder to x rays. On the same time scale a partial oxidation of Eu2+ to Eu3+ is observed by x-ray absorption near-edge spectroscopy (XANES), while for the trivalent dysprosium the valence state remains unchanged. The impact of these observations on the recently proposed models for persistent luminescence is discussed.

British Library Electronic Table of Contents (United Kingdom)

An analytical method was proposed for calculating radiative fluxes incident on a planar circular detector from a volume multiple point chemi- or bio-luminescent source inside a coaxial cylindrical reactor. The method was designed for a cylindrical reactor when the surface reflections were neglected and when chemi- or bio-luminescence reaches a detector embedded in the same homogeneous optical medium as the point emitters of the volume multiple point source model. The radiative fluxes from arbitrarily distributed point emitters were expressed by one generalized quadruple-integral formula. Then some double- and single-integral formulas were obtained for calculating radiative fluxes from identically radiating point emitters uniformly distributed within the reactor. Selected results were compu...

International Nuclear Information System (INIS)

Various compositions of Y(Ta,Nb)O4:Eu3+,Tb3+ with different Nb and activator concentrations have been investigated under UV and VUV excitation. Some compounds with very strong emission under VUV excitation were found. Such phosphors could be proposed as very good emissive materials for Displays and Lightings. The growing interest in luminescence spectroscopy of rare earth ions in the vacuum ultraviolet (VUV) and the visible (VIS) spectral range is due to industrial demands for new applications. YTaO4 and YNbO4 phosphors are a perspective class of efficient materials that are generally used in X-ray intensifying screens. These phosphors exhibit satisfying luminescence whenever excited by UV light, cathode radiation or X ray. However, to our knowledge, no work has been published on the VUV-excited luminescence for Eu3+ and Tb3+ double activated yttrium niobate and yttrium tantalate based phosphors. In this paper, the VUV-UV ...

CERN Document Server

Specification of the steel sheet for the 300 GeV magnet system

International Nuclear Information System (INIS)

... fields magnetic moments neel temperature neutron diffraction order-disorder

Science.gov (United States)

Magnetic forming coil design and development

CERN Document Server

Large scale magnetic field measurements and mapping

KoreaScience (Korea)

Full Text Available

Energy Technology Data Exchange (ETDEWEB)

Synthesis of silver nanoparticles based on a polyol process and variable frequency microwave (VFM) was investigated. Comparing to a thermal method, the reaction by VFM radiation was much faster. The effects of silver nitrate concentration, poly(N-vinylpyrrolidone) (PVP) concentration, reaction time and reaction temperature were studied. It was found that the higher concentration of silver nitrate, longer reaction time and higher temperature increased the particle size while the higher concentration of PVP decreased the particle size.

UK PubMed Central (United Kingdom)

Short and long-term pulmonary response to inhaled nickel hydroxide nanoparticles (nano-Ni(OH)₂, CMD = 40 nm) in C57BL/6 mice was assessed using a whole body exposure system. For short-term...Full Text Available

Energy Technology Data Exchange (ETDEWEB)

A mesoscopically ordered lamellar gel phase of a polymer-grafted, lipid-based complex fluid is used as a scaffolding to spatially organize inorganic nanoparticles. The complex fluid provides both a highly anisotropic environment and a segregated aqueous and organic domains in which inorganic nanoparticles can be selectively placed by tailoring their size and surface characteristics. Three types of silver nanoparticles -- underivatized, surfactant-stabilized, and dodecanthiol-derivatized -- were evaluated. Comparison of the surface plasmon resonance of the various silver particles dispersed in conventional solvents to those contained within the complex fluid was used to determine the region of spatial localization in the lamellar gel phase. Silver particles rendered hydrophobic by capping with an alkane thiol insert into the hydrocarbon bilayer region. Surfactant-stabilized and underivatized silver ...

Energy Technology Data Exchange (ETDEWEB)

A microemulsion comprised of water, Brij 78, pentanol and styrene into which PPO and bis-MSB had been dissolved was prepared. Polymerization of the styrene resulted in a suspension of fluor-containing polystyrene nanoparticles (<100 nm). After a concentration step, the aqueous nanosuspension was able to detect {sup 14}C with counting efficiencies over 50% of those of a commercially available scintillation cocktail. Monte Carlo calculations demonstrated that the size and concentration of the nanoparticles were appropriate for optimum detection efficiency.

Energy Technology Data Exchange (ETDEWEB)

In this note it is suggested that binuclear platinum(II) complexes with a solely inorganic bridging pyrophosphito ligand also possess many of the complementary advantages of inorganic and organic dyes. They are evaluated for their potential use as a luminescent solar concentrator material. The disadvantages include: the high cost of platinum; the absorption spectra in solution shows a weaker absorption at 452 nm which may cause reabsorption of emitted light; the positions of the absorption and emission maxima are not at the optimal wavelengths for absorption of sunlight and emission to a solar cell. In spite of these drawbacks the author believes the platinum complexes merit consideration for fabrication of solar concentrator devices.

International Nuclear Information System (INIS)

Capsulation of terbium(III) chloride in porous glass in the amount of 1.5-150 #mu#mole g"-"1 was carried out by impregnation of the glass substrate with variable concentrations of the salt aqueous solutions. Maximum luminosity of terbium(III) chloride in porous glass is found at its concentration of 120 #mu#mole g"-"1, that is close to the corresponding monolayer surface filling. Concentration dependences of terbium(III) luminescence and its quenching by adsorbed water are in agreement with the ideas of molecular fragmentation and uniform distribution of capsulated salt on the substrate surface

Energy Technology Data Exchange (ETDEWEB)

In this study, silver nanoparticles were formed on a natural macroporous matrix, the stem of rice-paper plant, by reducing Ag{sup +} in aqueous solution through in situ processing without using any other stabilizers. The pores of the matrix, with their size of about 100 {mu}m, were thought to act as reaction compartments for the nucleation and growth of silver nanoparticles, and the control of nucleation of silver crystal during the reduction reaction was found to be important to the successful formation of nanosized silver particles onto the matrix. The diameter and amount of resultant silver particles can be controlled by changing the reaction conditions. Under optimized conditions, the content of silver particles in the matrix can reach as high as 1.8 wt% with the particle diameters being kept below 100 nm. The anti-microbial activities in terms of minimum inhibitory concentration (MIC) for the silver nanoparticle ...

International Nuclear Information System (INIS)

Functionalizing nanoparticle surfaces is essential for achieving homogeneous dispersions of monodisperse particles in polymer nanocomposites for successful utilization in engineering applications. Functionalization reduces the surface energy of the nanoparticles, thereby limiting the tendency to agglomerate. Moreover, reactive groups on the surface can also participate in the polymerization, creating covalent bonds between the inorganic and organic phases. In this paper, a fluidized bed inductively coupled plasma (FB-ICP) reactor is used to break apart the agglomerates and functionalize commercial TiO2 nanoparticle powders in a batch of several grams. The fluidized bed could be implemented into a continuous flow reactor, potentially making this a viable method to treat larger quantities of commercial powders. The particles are treated with acrylic acid (AA) and tetraethylorthosilicate (TEOS) plasma and the functionalized ...

Energy Technology Data Exchange (ETDEWEB)

Carbon supported catalysts can lose their activity over a period of time due to the sintering of the nanometer-sized catalyst particles. The sintering of metal clusters on carbon supports can occur due to the weak interaction between the metal and the support and also due to the corrosion of carbon, especially in fuel cell electrocatalysts. The sintering may be reduced by increasing the interaction between the metal and the support and also by increasing the corrosion resistance of carbon supports. In an effort to mitigate the growth of the nanoparticles, carbon-substituted boron defects were introduced in the carbon lattice. The interaction between the Pt nanoparticles on the pure and boron-doped carbon supports was examined using X-ray photoelectron spectroscopy (XPS). The results indicate that the interaction between the Pt nanoparticles and the boron-doped carbon support was slightly stronger than the interaction ...

Energy Technology Data Exchange (ETDEWEB)

Magnetic separation of several classes of antibiotics was investigated using electrochemical magnetic seeding. Electrocoagulation with a sacrificial anode followed by addition of magnetite particles was applied for the magnetic seeding of antibiotics. With electrochemical magnetic seeding using an iron anode, tetracycline antibiotics (oxytetracycline, chlortetracycline, doxycycline and tetracycline) and cephalosporin antibiotic (cefdinir) were rapidly removed from synthetic wastewater by magnetic separation using a neodymium magnet. Iron and aluminium anodes were suitable for magnetic seeding of the antibiotics. The results indicated that the ability of antibiotics to form strong complex with iron and aluminium allowed the higher removal by magnetic separation. This method would be appropriate for rapid treatment of ...

Science.gov (United States)

In the present work, a new kind of myoglobin (Mb)/Au nanoparticles composite film was fabricated on pyrolytic graphite (PG) electrodes. Oppositely charged chitosan (CS) and silica (SiO(2)) nanoparticles were alternately adsorbed on the PG surface by the electrostatic interaction between them, forming {CS/SiO(2)}(5) layer-by-layer films. Mb and HAuCl(4) in solution were then simultaneously loaded into {CS/SiO(2)}(5) films. The loaded Au(III) in the films were electrochemically reduced into Au nanoparticles, forming nanocomposite films, designated as {CS/SiO(2)}(5)-Mb-Au. Various techniques such as cyclic voltammetry (CV), square wave voltammetry (SWV), quartz crystal microbalance (QCM), electrochemical impedance spectroscopy (EIS), scanning electron microscopy (SEM), and energy dispersive X-ray (EDX) analysis were used to characterize the films. Compared with {CS/SiO(2)}(5)-Mb films without Au ...

International Nuclear Information System (INIS)

... magnetic susceptibility magnetization monocrystals neutron diffraction

CERN Document Server

Checks are performed on the alignment of the magnets in the LHC tunnel. It is vital that each magnet is placed exactly where it has been designed so that the path of the beam is precisely controlled.

British Library Electronic Table of Contents (United Kingdom)

Blood kinetics and tissue distribution of 20, 80 and 110 nm silver nanoparticles were investigated in rats up to 16 days after intravenous administration once daily for 5 consecutive days. Following both single and repeated injection, silver nanoparticles disappeared rapidly from the blood and distributed to all organs evaluated (liver, lungs, spleen, brain, heart, kidneys and testes) regardless of size. The 20 nm particles distributed mainly to liver, followed by kidneys and spleen, whereas the larger particles distributed mainly to spleen followed by liver and lung. In the other organs evaluated, no major differences between the sizes were observed. Size-dependent tissue distribution suggests size-dependent toxicity and health risks. Repeated administration resulted in accumulation in li...

International Nuclear Information System (INIS)

Silica glasses containing Pr"3"+ with and without CdS nanoparticles were prepared by sol-gel technique. The influence of CdS nanoparticles on Pr"3"+ doped glass was studied by absorption, photoluminescence and up-conversion. From the measured intensities of various absorption bands of these glasses, the Judd-Ofelt parameters ?_2, ?_4 and ?_6 have been evaluated. The radiative transition probability (A), radiative lifetime (?_R), branching ratio (?_R) and integrated emission cross-section (?_P) were calculated from excited states of "3P_1 and "3P_0 levels. The up-conversion emissions were found in the green, orange and red regions under 800 nm excitation with peaks 559, 612 and 688 nm respectively. On excitation with 370 nm also leads to similar green, orange and red regions.

Energy Technology Data Exchange (ETDEWEB)

A detailed comparison of the softness of gold and silver has been reported in the light of hard soft acid base (HSAB) principle. Gold and silver nanoparticles in organic media (i.e., organosol) have been exploited individually to establish the principle. Sulfur and nitrogen were employed as soft and borderline donating atoms to examine the metal-ligand interactions. In this regard, thiols and amines have been considered as interacting ligands with sulfur and nitrogen donor atoms respectively. The stronger affinity of gold towards softer sulfur donor as compared to nitrogen and conversely a reasonable interaction of silver nanoparticles with both the atoms authenticate the softer nature of gold nanoparticle as compared to silver one.

International Nuclear Information System (INIS)

The structure of nano-porous carbon, obtained by means of chlorination of carbide compounds with various crystal structure (SiC, TiC, Mo_2C) is studied through the method of small-angle diffraction. The angular dependences of the scattering intensity obtained are interpreted as the result of scattering from the nanoparticles of different size. The functions of the scattering particles distribution by the m(R_g) inertia radii are determined. It is shown that in spite of the source carbide, the highest fraction of the volume in the porous carbon constitute the particles with R_g #approx# 5 A. The nanoparticles in the samples obtained from SiC, wherein the average value of the R_g"a"v < 6 A, are most uniform by size. The nanoparticles in the porous carbon, obtained from Mo_2C, are on the average by two times larger

International Nuclear Information System (INIS)

We report on the fabrication of nanomechanical devices for shuttling of electrons from one electrode to another. Each device consists of a 20 nm diameter gold nanoparticle embedded within the gap between two gold electrodes. In two different kinds of shuttle-junctions the nanoparticle is attached to the electrodes through either (i) a single layer of 1,8-octanedithiol or (ii) a multilayer of 1-octanethiol molecules. The thiol layers play the role of 'damped springs', such that when a sufficient voltage bias is applied to the junction, the nanoparticle is expected to start oscillating and thereby transferring electrons from one electrode to the other. For both kinds of shuttle-junctions we observed an abrupt increase in the transmitted current above a threshold voltage, which can be attributed to a transition from the stationary to the oscillating regime. The threshold voltage was found to be lower for single-layer ...

International Nuclear Information System (INIS)

We report studies of bimetallic nanoparticles with 15%-16% atomic crystal parameters size mismatch. The degree of alloying was probed in a 2-nm Pt core (smallest attainable core size) of Pt-Ag nanoparticles (completely immiscible in bulk) and 20-nm-diameter Pd-Ag nanowires (completely miscible in bulk). Particles were synthesized radiolytically, and depending on the initial parameters, they assume spherical or cylindrical (nanowire) morphologies. In all cases, the metals are seen to follow their bulk alloying characteristics. Pt and Ag segregate in both spherical and wire forms, which indicates that strain due to crystallographic mismatch overcomes the excess surface free energy in the small particles. The Pd-Ag nanowires alloy similar to previously reported spherical Pd-Ag particles of similar diameter and composition.

Energy Technology Data Exchange (ETDEWEB)

The magnetic fluid is a colloidal suspension of magnetite in kerosene, prepared by a low-cost process. Separation is accomplished in an open trough filled with magnetic fluid. A magnetic field is established in the fluid, by energizing an electromagnet having poles on each side of the trough. Due to the design of the magnet poles and air gaps, the magnetic field is strongest at the bottom, about 10,000 oersteds, and uniformly decreases in strength to about 2000 oersteds at the top of the fluid. Therefore, the magnetic field gradient increases with depth. The magnetic force attracts the entire separation medium (magnetic fluid) creating a reaction force of equal magnitude and acting in the opposite direction. This reaction created within a magnetic fluid/magnetic field combination ...

Energy Technology Data Exchange (ETDEWEB)

Flux-grown ScPO{sub 4} single crystals exhibit a number of luminescence bands in their x-ray-excited luminescence spectra - including sharp lines arising from rare-earth elements plus a number of broad bands at 5.6 cV, 4.4 eV, and 3 eV. The band at 5.6 eV was attributed to a self-trapped exciton (STE) [l], and it could be excited at 7 eV and higher energies. This luminescence is strongly polarized (P = 70 %) along the optical axes of the crystal and exhibits a kinetic decay time constant that varies from several ns at room temperature to {approximately}10 {micro}s at 60 K and up to {approximately}1 ms at 10 K. It is assumed that the STE is localized on the SC ions. The band at 3 eV can be excited in the range of the ScPO{sub 4} crystal transparency (decay time = 3 to 4 {micro}s.) This band is attributed to a lead impurity that creates different luminescence centers. At high temperatures, the band at 4.4 ...

International Nuclear Information System (INIS)

We have tested the suitability of a new single-aliquot regenerative-dose protocol for estimating the equivalent dose (D_e) in polymineral fine grains extracted from colluvia from various sites in Germany. First, we report the behaviour of three OSL signals: (i) blue-stimulated, (ii) infrared-stimulated luminescence, and (iii) blue-stimulated luminescence following infrared (IR) stimulation, using a near-UV (290-380 nm) detection window in each case. For these three signals, there is a significant change in sensitivity with regeneration cycle; this change can be compensated for using the response to a fixed test dose after each natural or regenerated measurement. The source of the three luminescence signals is then investigated using pulse-anneal and elevated-temperature experiments. Fading tests on laboratory-induced signals show that although the IR signals fade by up to 23% in 15 days at 100 deg. C, the post-IR blue ...

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UK PubMed Central (United Kingdom)

BackgroundBaculovirus, which has a width of 40 nm and a length of 250-300 nm, can display functional peptides, receptors and antigens on its surface by their fusion with a baculovirus...Full Text Available

Energy Technology Data Exchange (ETDEWEB)

The surface enhanced Raman scattering (SERS) spectra of piperidine in silver colloid solution, on roughened silver electrode and on roughened silver electrode modified with silver nanoparticles were studied, and the high-quality SERS spectra of piperidine on roughened silver electrode modified with silver nanoparticles were obtained for the first time. Surface selection rules derived from the EM enhancement model were employed to deduce piperidine orientations on the different surfaces. On the basis of this, two models of piperidine adsorbed on the surface of the silver nanoparticles were built, and DFT-B3PW91/LanL2dz was applied to calculate the Raman frequencies. It proves that, at higher potential values, the piperidine is perpendicularly standing on the roughened silver electrode surface though its lone-electron pair, but in silver colloid solution and on the silver nanoparticles modified silver ...

Energy Technology Data Exchange (ETDEWEB)

A method to control charge transfer reaction in DNA using hybrid nanometer-sized TiO{sub 2} nanoparticles was developed. In this system extended charge separation reflects the sequence of DNA and was measured using metallic silver deposition or by photocurrent response. Light-induced extended charge separation in these systems was found to be dependent on the DNA-bridge length and sequence. The yield of photocatalytic deposition of silver was studied in systems having GG accepting sites imbedded in AT runs at varying distances from the TiO{sub 2} nanoparticle surface. Weak distance dependence of charge separation indicative of a hole hopping through mediating adenine (A) sites was found. The quantum yield of silver deposition in the system having a GG accepting site placed 8.5 {angstrom} from the nanoparticle surface was found to be {Phi} = 0.70 (70%) and {Phi} = 0.56 (56%) for (A){sub n} and (AT){sub n/2} bridge, ...

UK PubMed Central (United Kingdom)

BackgroundFor more than a decade there has been increasing interest in the use of nanotechnology and microarray platforms for diagnostic applications. In this report, we describe...Full Text Available

UK PubMed Central (United Kingdom)

BackgroundAntigen sparing and cross-protective immunity are regarded as crucial in pandemic influenza vaccine development. Both targets can be achieved by adjuvantation strategy...Full Text Available

UK PubMed Central (United Kingdom)

Clinical applications of genetic therapies, including delivery of short, interfering RNAs (siRNAs) for RNA interference (RNAi), are limited due to the difficulty of delivering nucleic acids...Full Text Available

UK PubMed Central (United Kingdom)

BackgroundParticulate systems are well known to be able to deliver drugs with high efficiency and fewer adverse side effects, possibly by endocytosis of the drug carriers. On the...Full Text Available

International Nuclear Information System (INIS)

... radiations isotopes magnetic moments nuclear cascades nuclear properties

Science.gov (United States)

... in the design of such devices as fusion reactors, magnetohydrodynamic generators, magnetically levitated vehicles, magnetic forming devices, and ...

Science.gov (United States)

Decoupling force exerted by magnetic forming Be coil assembly on metallic plate during forming

Science.gov (United States)

Selective removal of hexavalent chromium ions from aqueous solutions using a chitosan/gold nanoparticles composite film was demonstrated. Localized surface plasmon resonance (LSPR) was used to measure the interface stability and detect the incorporation of chromium ions over time. The effects of pH, ethylenediaminetetraacetic acid (EDTA), and various foreign ions such as trivalent chromium, sodium, calcium, phosphate, sulfate and chloride on the adsorption of hexavalent chromium were investigated. PMID:19381379

Energy Technology Data Exchange (ETDEWEB)

SnO{sub 2}-carbon nanotube (CNT) composite sheets are synthesized using poly(vinylpyrrolidone) to uniformly load a monolayer of SnO{sub 2} nanoparticles onto the surfaces of CNTs and CNT bundles within cross-stacked CNT sheets. When they are used as high-capacity (over 850 mA h g{sup -1}) and binder-free anodes in rechargeable lithium-ion batteries, they exhibit good cycle performance. (Abstract Copyright [2009], Wiley Periodicals, Inc.)

International Nuclear Information System (INIS)

Luminescence and reflection spectra as well as luminescence kinetics of the 1 mol% Sm3+-doped crystalline lanthanum magnesium meta borate (LaMgB5O10) and gadolinium magnesium meta borate (GdMgB5O10) were analyzed. Materials were synthesized by conventional solid state route and showed bright orange-red emission under UV excitation. Emission spectra contain sharp and well resolved Sm3+4G5/2#->#6HJ transitions indicating a strong crystal-field effect. In case of gadolinium compound energy transfer between Gd3+ and Sm3+ was detected. The luminescent kinetics of the Sm3+ in analyzed powders is characterized by single exponential decay and experimental values vary in the range 2.2-2.4 ms. - Research highlights: ? Phosphorescence of samarium-doped lanthanide magnesium meta borates. ? Bright and well resolved orange-red emission of Sm3+ under UV excitation. ? Energy transfer from Gd3+ to Sm3+ in gadolinium magnesium meta borate ...

British Library Electronic Table of Contents (United Kingdom)

The reaction of the chelating ligands (obtained by the condensation of 2-hydroxy-1-naphthaldehyde with various primary amines) with [RuHCl(CO)(EPh3)2(B)] (where E=P; B=PPh3, py or pip: E=As; B=AsPh3) in benzene afforded new stable ruthenium(II) carbonyl complexes of the general formula [Ru(Cl)(CO)(EPh3)(B)(L)] (L=anion of bidentate Schiff bases). The structure of the new complexes was investigated using elemental analyses, spectral (FT-IR, UV-vis and 1H NMR) and electrochemical studies and is found to be octahedral. All the metal complexes exhibit characteristic MLCT absorption and luminescence bands in the visible region. The luminescence efficiency of the ruthenium(II) complexes was explained based on the ligand environment around the metal ion. These complexes catalyze oxidation of prim...

Energy Technology Data Exchange (ETDEWEB)

Anomalous fading of the feldspar infrared stimulated luminescence (IRSL) signal hampers possibilities of using feldspar IRSL to obtain burial ages for sediments beyond the dating range of quartz optically stimulated luminescence. Here, we propose a new approach to quantify anomalous fading of the feldspar IRSL signal over geological burial times based on laboratory fading experiments. The approach builds on the description of the quantum mechanical tunnelling process recently proposed by Huntley [2006. An explanation of the power-law decay of luminescence. J. Phys. Condensed Matter 18, 1359-1365]. We show that our methods allow the construction of un-faded and natural IRSL dose-response curves as well as anomalous fading rates in field saturation. The predicted level of field saturation closely approximates the measured saturation level for five samples from fluvial deposits (Lower Rhine) known to be older than 1 Ma. The ...

International Nuclear Information System (INIS)

In order to examine the state of technology of all areas of magnetic suspension and to review related recent developments in sensors and controls approaches, superconducting magnet technology, and design/implementation practices, a symposium was held. The proceedings are presented. The sessions covered the areas of bearings, sensors and controls, microgravity and vibration isolation, superconductivity, manufacturing applications, wind tunnel magnetic suspension systems, magnetically levitated trains (MAGLEV), space applications, and large gap magnetic suspension systems.

Energy Technology Data Exchange (ETDEWEB)

The goal of the present work was to develop a new synthetic nanosystem for gene delivery. For this purpose, we chose two polysaccharides, hyaluronic acid (HA) and chitosan (CS), as the main components of the nanocarrier. Nanoparticles with different hyaluronate:chitosan (HA:CS) mass ratios (0.5:1 and 1:1) and different polymer molecular weights (hyaluronate 170 (HA) or <10 kDa (HAO) and chitosan 125 (CS) or 10-12 (CSO) kDa) could be obtained using an ionic crosslinking method. These nanoparticles were loaded with pDNA and characterized for their size, zeta potential and pDNA association efficiency. Moreover, their toxicity and ability to transfect the model plasmid pEGFP-C1 were evaluated in the cell line HEK 293, as well as their intracellular fate. The results showed that HA:CS nanoparticles have a small size in the range of 110-230 nm, a positive zeta potential of +10 to +32 mV and a very high pDNA association ...

Energy Technology Data Exchange (ETDEWEB)

A novel system for real-time radiation monitoring in reactor or accelerator facilities has been studied using an imaging plate. The authors made a feasibility study on a new neutron detection system using both photostimulated luminescence (PSL) and prompt luminescence (PL) generated in a neutron imaging plate (NIP) when the NIP is irradiated by neutrons. A readout system consisting of a semiconductor laser and a photomultiplier tube was fabricated for the purpose. It was confirmed that the system can measure both PSL and PL, where Am-Li was used as a neutron source. It may be possible to establish a new wide-range neutron monitoring system using the developed system as a PL mode normally, and as a PSL mode in case of intense neutron dose that cannot be measured in a PL mode because of saturation of the detection system. (author)

Energy Technology Data Exchange (ETDEWEB)

Thermoluminescence of inorganic dust extract from herbs and spices has been demonstrated to be a useful method to discriminate irradiated food products as well as to estimate the total dose exposure. The time evolution of infrared stimulated luminescence has been systematically investigated in potassium feldspar and albite minerals subjected to different doses of gamma irradiation (ranging from 0 to 8 kGy). Experimental results reveal a 300-600 nm signal which is greatly intensified for irradiated samples, following the same irradiation dose dependence observed in thermoluminescence. The luminescence intensity disappears after few seconds of illumination, following a time evolution which is proportional to (1 + Bt){sup -P}. The influence of both B and P factors upon the irradiation dose has been systematically analysed. (author)

International Nuclear Information System (INIS)

LaPO4 single crystals lightly doped with Er3+, and codoped with Er3+ and Yb3+ have been grown by spontaneous nucleation in a lead phosphate flux. Absorption and luminescence spectra have been measured in the visible and near-IR regions and the excited state dynamics has been studied upon pulsed laser excitation. The obtained results have allowed the evaluation of the effective emission cross-sections around 1.5 ?m, that have been found to be similar to important oxide laser crystals doped with Er3+. Efficient visible upconversion has been observed upon excitation at 980 nm in the codoped crystals. This behaviour is attributed to Yb3+-Er3+ energy transfer processes.

International Nuclear Information System (INIS)

The characteristics of infrared-stimulated luminescence (IRSL) from a sample of potassium feldspar at low temperatures are presented. These studies extend the previous work from this laboratory on the optical bleaching characteristics and emission spectra of feldspars at room temperature and recent measurements of the stimulated spectrum for a sample of potassium feldspar at room temperature. Stimulation spectra have been measured at 290, 160 and 145 K. By fitting Gaussian functions to the spectra, the peak position is shown to shift to higher photon energies at lower temperatures and the full-width half-maximum of the peak to reduce with decreasing temperature. The variation of IRSL intensity with temperature for several stimulating wavelengths has been determined and the form of the IRSL decay curve measured at 290 and 160 K. No substantial differences were observed in the form of the decay curves at each temperature. (author).

International Nuclear Information System (INIS)

The effects of O and C ion implantation with different implantation doses on the yellow luminescence (YL) from unintentional doped n-type GaN have been studied by the photoluminescence (PL) spectra. O and C ions were implanted in the GaN samples with different doses from 1.0 x l013 to 1.0 x l017cm-2. Post-annealing was done in a quartz open-tube furnace under flowing N2 gas for 30 min at 950 degree C. By comparing with N ion implanted samples, it is assumed that different deep-level centers involving in the YL were produced in GaN after O and C ion implantation. In addition, with a dose of 1017 cm-2, the concentration of deep C centers involving in the YL was enhanced markedly. (authors)

International Nuclear Information System (INIS)

A non-contact method, using magnetic drag force principle, was proposed to design the braking systems to improve the shortcomings of the conventional braking systems. The extensive literature detailing all aspects of the magnetic braking is briefly reviewed, however little of this refers specifically to upright magnetic braking system, which is useful for industries. One of the major issues to design upright magnetic system is to find out the magnetic flux. The changing magnetic flux induces eddy currents in the conductor. These currents dissipate energy in the conductor and generate drag force to slow down the motion. Therefore, a finite element model is developed to analyze the phenomena of magnetic flux density when air gap and materials of track are varied. The verification shows the predicted magnetic flux is within ...

International Nuclear Information System (INIS)

To investigate the magnetic fluctuations and for further transport study, the poloidal and radial magnetic field measurement is conducted on the Sino United Spherical Tokamak (SUNIST). Auto-power spectral density indicates that the magnetic fluctuation energy mainly concentrates in the frequency region lower than 10 kHz. The magnetic field oscillations, which are characterized by harmonic frequencies of 40 kHz, are observed in the scrape-off layer; by contrast, in the plasma core, the magnetic fluctuations are of Gaussian type. The time-frequency profiles show that the poloidal magnetic fluctuations are temporally intermittent. The autocorrelation calculation indicates that the fluctuations in decorrelation time vary between the core and the edge. (authors)

International Nuclear Information System (INIS)

Data of thermally stimulated luminescence (TSL) of single (Cu), double (Cu, Mn) and triple (Cu, Mn, Gd) activated SrS phosphors, which throws light on the nature and distribution of deeper traps have been presented. The samples are prepared by Bhawalkar's method and excited by UV 365 nm and #gamma#-rays to study the phenomenon. (author). 8 refs., 2 figs., 1 tab.

Energy Technology Data Exchange (ETDEWEB)

It may be necessary to reduce microbiological contamination of crude drugs (medicinal plants or their parts like roots, leaves, flowers). This can be done by treating the drugs with ionizing radiation. Meethods for detection of such an irradiation were developed. It could be pointed out that measurements of luminescence, viscosity and electron spin resonance were suitable for specific drugs, but not for all drugs. (orig.).

British Library Electronic Table of Contents (United Kingdom)

Fiber optic metrology developed at the CEA LIST laboratories involves fiber Bragg grating sensors, distributed Brillouin optical time domain reflectometry and optically stimulated luminescence dosimetry. Recent activities in optical fiber sensing are reviewed from laboratory experiments to field trials.

Energy Technology Data Exchange (ETDEWEB)

The authors investigate the breakdown luminescence spectra in reverse-biased p-n heterojunctions based on gallium and aluminum phosphides and arsenides for the purpose of determining their behavior as lasing and photodetection materials. Data are given on temperature coefficients, band gap structure, bremsstrahlung, hot carrier mobility and photon emission, and transition and recombination parameters.

Energy Technology Data Exchange (ETDEWEB)

Potassium clusters arrayed in zeolite A are known to show ferromagnetic properties at low temperature. The origin of the spontaneous magnetization has been explained by a model of spin-canting in an antiferromagnetically ordered state. The direct information for the magnetic structure, however, has not been obtained so far. In the present work, we measure the neutron powder diffraction by using pulsed neutron source at KEK-KENS below and above the Curie temperature. No significant temperature-dependence was, however, obtained within the statistical errors, namely, magnetic scattering could not be detected separately. We also estimate the intensity of magnetic scattering by assuming some possible magnetic structures with considering the magnetic form factor of the cluster wave function. The intensity of magnetic scattering is estimated to be ...

International Nuclear Information System (INIS)

Scanning ion microscopy with polarization analysis (SIMPA) is used to study the spin-resolved surface magnetic structure of nano-sized magnetic systems. SIMPA is utilized for in situ topographic and spin-resolved magnetic domain imaging as well as for focused ion beam (FIB) etching of desired structures in magnetic or non-magnetic systems. Ultra-thin Co films are deposited on surfaces of Si(1 0 0) substrates, and ultra-thin, tri-layered, bct Fe(1 0 0)/Mn/bct Fe(1 0 0) wedged magnetic structures are deposited on fcc Pd(1 0 0) substrates. SIMPA experiments clearly show that ion-induced electrons emitted from magnetic surfaces exhibit non-zero electron spin polarization (ESP), whereas electrons emitted from non-magnetic surfaces such as Si and Pd exhibit zero ESP, which can be used to calibrate sputtering rates in situ. We ...

Energy Technology Data Exchange (ETDEWEB)

A model is available in predicting flocculation frequencies between particles of various properties under the influence of a magnetic field. This model provides a basic understanding of fundamental phenomena, such as particle-particle and particle-collector interactions, occurring in HGMF (high gradient magnetic field), and will be extended to describe experimental data of particle flocculation and filtration and predict the performance of high- gradient magnetic filters. It is also expected that this model will eventually lead to a tool for design and optimization of magnetic filters for environmental, metallurgical, biochemical, and other applications.

Energy Technology Data Exchange (ETDEWEB)

Mono-dispersed cubic CeO{sub 2} nanoparticles have been synthesized using a surfactant-assisted method with laurylamine hydrochloride and cerium alkoxide modified with acetylacetone in an aqueous solution system. The prepared cubic CeO{sub 2} nanoparticles had a highly crystallized structure at 353 K and formed rod-like structures by calcination at 673 K after freeze-drying the CeO{sub 2} gel. We discovered a clear potential to make 1D, 2D or 3D CeO{sub 2}-materials with a well-controlled characteristic length and shape by assembling cubic-shaped CeO{sub 2} nanoparticle building blocks. CeO{sub 2}-TiO{sub 2} composite nanostructures have also been synthesized by changing the mole ratio of cerium alkoxide/titanium alkoxides. By utilizing the redox characteristic of CeO{sub 2}, CeO{sub 2} nanoparticles and CeO{sub 2}-TiO{sub 2} composite nanostructures after calcination, showed reaction activity toward ...

Energy Technology Data Exchange (ETDEWEB)

A tutorial account is given of the main characteristics and distinctive features of conceptual magnetic fusion systems employing the magnetic mirror principle. These features are related to the potential advantages that mirror-based fusion systems may exhibit for the generation of economic fusion power.

Energy Technology Data Exchange (ETDEWEB)

An introduction to time-of-flight neutron spectroscopy is presented in the context of the study of magnetic materials. Examples are taken from the class of rare earth and actinide magnetic materials known as `strongly correlated electron` systems. (author) 11 figs., 24 refs.

Energy Technology Data Exchange (ETDEWEB)

The disclosure is directed to an active magnetic regenerator apparatus and method. Brayton, Stirling, Ericsson, and Carnot cycles and the like may be utilized in an active magnetic regenerator to provide efficient refrigeration over relatively large temperature ranges.

International Nuclear Information System (INIS)

The CaWO_4:Ln"3"+ SiO_2 (Ln=Tb, Dy and Ho) nanoparticles were synthesized via a combustion process at 800 "oC, using citric acid as chelating agent and fuel, ammonium nitrate as fuel, boric acid as flux material and silica as supports. The persistent phosphor nanoparticles were characterized by X-ray diffraction (XRD), reflectance UV-vis and fluorescence spectroscopy (PL) and transmission electron microscopy (TEM) techniques. XRD patterns indicated that crystalline calcium tungstate with scheelite structure was produced. The reflectance UV-vis spectra showed the broad absorption band of WO_4"2"- groups and the PL spectra showed the WO_4"2"- wide excitation band, broad emission band of WO_4"2"- and characteristic emissions of Ln"3"+ ions. The average particle sizes were determined by TEM, which are about 50 nm.

Energy Technology Data Exchange (ETDEWEB)

CeO{sub 2} undergoes a first-order phase transition from fluorite to {alpha}-PbCl{sub 2}-type structure under high pressure. To evaluate the changes in physical properties of CeO{sub 2} nanomaterials as the particle size decreasing, high-pressure Raman study under quasi-hydrostatic condition has been performed on CeO{sub 2} nanospheres self-assembled by 5 nm CeO{sub 2} nanoparticles at room temperature. Surprisingly, as the pressure elevate to 34 GPa, the CeO{sub 2} nanospheres still retain the cubic fluorite-type structure, indicating the sample is more stable than the bulk counterpart. Whereas, previous high-pressure studies show the phase transition at 22.3/26.5 GPa for 12 nm CeO{sub 2} nanoparticles, which is less stable than the bulk materials. The enhancement of phase stability might be attributed to the increase of surface energy of CeO{sub 2} nanospheres as the size of the building units decrease. (Copyright copyright 2011 WILEY-VCH ...

Science.gov (United States)

We report here a new approach to introduce the effect of chemisorption in the Monte-Carlo simulation procedure for studying the segregation behaviour in bimetallic nanoparticles at low pressures. A coordination-dependent pair interaction energy is constructed in terms of partial bond energies and the exchange energy where the partial bond energy can be empirically calculated from the experimental values of dimer energy, the pressure-dependent surface energy and the bulk cohesive energy of the constituent metals. The advantage of this procedure is the ability to estimate the pressure-dependent surface composition of the nanoparticles. The method has been applied to oxygen-adsorbed Pd-Ag systems; and it is found that while Ag segregate in clean particles, at higher oxygen pressures Pd atoms segregate to the surface. The present technique has been argued to be suitable for higher pressures (>10-5Torr) when coverage cannot be accurately ...

International Nuclear Information System (INIS)

Parameters of permanent magnets result from the combination of intrinsic properties such as saturation magnetization, magnetic exchange, and magnetocrystalline energy, as well as microstructural parameters such as phase structure, grain size, and orientation. Reduction of grain size into nanocrystalline regime (#approx# 50 nm) leads to the enhanced remanence which derives from ferromagnetic exchange coupling between highly refined grains. In this study the fundamental phenomena, quantities, and structure parameters, which define nanophase permanent magnets are presented and discussed. The theoretical considerations are confronted with experimental data for nanocrystalline Sm-Fe-N type permanent magnets. (author)

UK PubMed Central (United Kingdom)

OBJECTIVE--The study was performed to examine the influence of the exposure to magnetic fields in the potrooms of an electrolysis plant on the occurrence of musculoskeletal symptoms among the employees....Full Text Available

Energy Technology Data Exchange (ETDEWEB)

The Muon Ionization Cooling Experiment (MICE) focusing solenoid magnets focus the muon beam within the MICE cooling channel on a liquid or solid absorber that is within the warm bore of solenoid. The focusing magnet has a warm bore of 470 mm. his magnet consists of two coils 210-mm long that is separated by an aluminum mandrel that is 200 mm long. Each of the coils has its own leads. The coils may be operated in either the non-flip mode (solenoid mode with both coils at the same polarity) or the lip mode (quadrupole focusing mode where both coils are at opposite polarity). This report describes the focusing solenoid magnet design that will be built by the vendor. The progress on the construction of the first of the focusing magnets will also be discussed in this report. Ultimately three of these magnets will be built. These magnets will be ...

Science.gov (United States)

... 31. New electric forming methods offer potentials for light metals; magnetic forming and plasma forming. ... 3, 25 Magnetic Forming ..... ...

International Nuclear Information System (INIS)

Highly ordered arrays of Ni nanoholes and Fe20Ni80 antidots have been prepared, respectively, by replica/antireplica processing and sputtering techniques using nanoporous alumina membranes as templates. Geometrical characteristics as nanohole/antidot diameter, interpore distance and the overall hexagonal symmetry of arrays are controlled through the original templates. Experimental data on their hysteresis and magnetic domain structure have been taken by vibrating sample magnetometry and magnetic force microscopy, respectively. An analysis of the magnetization process, resulting magnetic anisotropy and magnetic domain structure is summarized considering the influence of those geometry aspects. In particular, the hexagonal symmetry and the density of nanohole/antidots determine the overall magnetic behavior, which is of interest in future high-density ...

Science.gov (United States)

Effective localization of small magnets against a noisy, real world background can involve various methods to first identify the magnetic fields produced by the magnet of interest, then to filter out background noise, and then to analyze the available magnetic field data to localize the magnet. Here we discuss low cost techniques which allow localization of small magnets with field strengths in the milliGauss range against real world background fields in the range of hundreds of mG, which may be fluctuating by up to tens of mG. Such techniques allow magnet tracking to be used to localize catheters in place of more invasive and expensive methods, e.g. fluoroscopy, for a variety of applications, including drug infusion with peripherally inserted central catheters (PICCs), laser ablation (TMR, PTMR) and introduction of pacemaker leads.

International Nuclear Information System (INIS)

The dynamic response of cylindrical and ring-shaped YBaCuO bulk parts to pulsed magnetic fields is calculated by using small sets of finite elements. Some comparisons with experimental results are provided, and they give confidence in the modelling of the superconducting properties. Transient magnetizations as a function of time and space as well as shapes and absolute values of trapped magnetic flux profiles are presented. The influence of the sample geometry is investigated for different millisecond pulsed magnetization processes. Results are reported for different radial thicknesses and heights, different pulse durations, peak magnetic fields and pulse sequences with and without stepwise cooling. Comparisons concerning the achievable trapped magnetic field and flux are made, and implications for the use of high-temperature superconductor bulk parts as ...

Energy Technology Data Exchange (ETDEWEB)

A nanosuspension of magnetically tagged metronidazole was developed by the solvent displacement method coupled with ultrasonication and was evaluated for its physicochemical properties. The drug release from metronidazole magnetic nanosuspension at pH 1.2 and 7.0 shows maximum correlation coefficient for zero order and Higuchi model, respectively. The anthelmintic activity of the formulated metronidazole magnetic nanosuspension was evaluated on Indian earthworms (Pheretima poi). Metronidazole magnetic nanosuspension at a dose of 10 and 50 mg/ml shortened by 31% and 34%, respectively, the mean time to death of the earthworms when compared against a non-magnetic metronidazole suspension. Thus, the developed metronidazole magnetic nanosuspension showed potent, controlled and targeted drug action and might be a good therapeutic avenue in combating infectious GI ...

Science.gov (United States)

... design, and manufacturing knowledge have been acquired and used to develop an 'in-house' capability for the fabrication of magnetic forming coils ...

Science.gov (United States)

has been generally related to magnetic forming. One of the methods suggested was the following: A "pancake" magnetic coil is placed over a thin aluminum ...

Energy Technology Data Exchange (ETDEWEB)

For the purpose of solving the limitations such as shape and dimension for magnetic compact fabricated by conventional anisotropic forming under magnetic orienting field, the feasibility of a new magnetic forming process was studied. Ferrite powder mixed with UV resin was compacted in the die mold and followed by alignment under the magnetic field. Effects of viscosity of UV resin and forming condition on magnetic characteristics of the compact was investigated. Maximum degree of alignment for the ferrite powder reached to 0.826. It was predicted that the proposed method had make it possible to fabricate a high performance magnet having the anisotropic alignment of the magnetic powder. The UV resin is desirable to have low viscosity, good properties such as formability and configuration stability for the compact and also parting- ability ...

British Library Electronic Table of Contents (United Kingdom)

In this paper, multilayer oxide nanorods were deposited in the nanopores of anodic aluminum oxide (AAO) via solution infiltration followed by heat treatment. The nanorods have a core-shell structure. First, the shell (nanotube) with the thickness of about 40nm was made of TiO"2 through the hydrolysis of (NH"4)"2TiF"6. Second, silver nanoparticles with the diameter of about 3nm were added into the TiO"2 layer through thermal decomposition of AgNO"3 at elevated temperatures. Then, cylindrical cores (nanorods) of CoO and ZnO with 200nm diameter were prepared, respectively. Scanning electron microscopy (SEM) and transmission electron microscopy (TEM) were used to characterize the structure and composition of the nanorods. UV-vis light absorption measurements in the wavelength range from 350 to...

British Library Electronic Table of Contents (United Kingdom)

A stable BSA blocking poly(dimethylsiloxane) (PDMS) microchannel was prepared based on in situ synthesized PDMS-gold nanoparticles composite films. The modified microchip could successfully suppress protein adsorption. The assembly was followed by contact angle, charge-coupled device (CCD) imaging, electroosmotic flow (EOF) measurements and electrophoretic separation methods. Contact angle measurements revealed the coated surface was hydrophilic, water contact angle for coated chips was 45.2^o compared to a water contact angle for native PDMS chips of 88.5^o. The coated microchips exhibited reproducible and stable EOF behavior. With FITC-labeled myoglobin incubation in the coated channel, no fluorescence was observed with CCD image, and the protein exhibited good electrophoretic effect in ...

Energy Technology Data Exchange (ETDEWEB)

We report the simultaneous formation of self-assembled surface ripples in Cd{sub 2}Nb{sub 2}O{sub 7} pyrochlore caused by focused ion beam (FIB) patterning and uniformly distributed metallic nanodots induced by phase decomposition under ion bombardment. The characteristic wavelength of the surface ripples is controllable from the nm to the sub-{micro}m scale. High-density Cd metallic nanoparticles, {approx} 5 nm, formed and the distribution of nanoparticles is consistent with the morphological characteristics of the ripple pattern. This approach provides a means of fabricating surface nanostructure with various patterns and a controllable particle size and distribution by combining ion beam-induced phase decomposition with high-precision FIB patterning.