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 ...

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An electrochemical biosensor for determination of hydrogen peroxide (H2O2) was fabricated, based on the electrostatic immobilization of horseradish peroxidase (HRP) with one-dimensional gold nanowires (Au NWs) and TiO2 nanoparticles (nano-TiO2) on a gold electrode. The nano-TiO2 can give a biocompatible microenvironment and compact film, and the Au NWs can provide fast electron transferring rate and greatly add the amount of HRP molecules immobilized on the electrode surface. Au NWs were characterized by ultraviolet?visible spectra and transmission electron microscope. The electrode modification process was probed by cyclic voltammetry and electrochemical impedance spectroscopy. Chronoamperometry was used to study the electrochemical performance of the resulting biosensor. Under optimal co...

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.

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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.

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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.

Science.gov (United States)

A simple one-step method to fabricate hierarchically porous TiO2/Pd composite hollow spheres without any template was developed by using solvothermal treatment. Pd nanoparticles (2-5 nm) were well dispersed in the mesopores of the TiO2 hollow spheres via in-situ reduction. In our experiment, polyvinylpyrrolidone played an important role in the synthetic process as the reducing agent and the connective material between TiO2 and Pd nanoparticles. HF species generated from solvothermal reaction leaded to the formation of TiO2 hollow spheres and Ostwald ripening was another main factor that affected the size and structure of the hollow spheres. The as-prepared TiO2/Pd composite hollow spheres exhibited high electrocatalytic activity towards the reduction of H2O2. The sensitivity was about 226.72 ?A mM-1 cm-2 with a detection limit of 3.81 ?M at a signal-to-noise ratio of 3. These results made the hierarchically porous TiO2/Pd composite a promising ...

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 ...

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In this work, we have investigated the capability of different bimetallic nanoparticle alloy combinations to be used in fibre optic sensors based on the technique of surface plasmon resonance. The metals considered for this analysis are silver, gold, copper and aluminium. The performance of the sensor with different bimetallic nanoparticle alloy combinations is evaluated and compared numerically. The performance is analysed in terms of three parameters: sensitivity, signal-to-noise ratio (SNR) and operating range for the sensing layer refractive index values. On the basis of the comparison and some logistic criteria, the best possible bimetallic alloy combinations along with a requisite alloy composition ratio are predicted. The bimetallic nanoparticle alloy combination is capable of simultaneously providing larger values of sensitivity, SNR and operating range, which is not possible with any single ...

International Nuclear Information System (INIS)

Direct electrochemistry and electrocatalysis of catalase (Cat) was studied based on a nano-composite film consisting of amine functionalized graphene and gold nanoparticles (AuNPs) modified glassy carbon electrode. Graphene was synthesized chemically by Hummers and Offeman method and then was functionalized with amino groups via chemical modification of carboxyl groups introduced on the graphene surface. The nano-composite film showed an obvious promotion of the direct electron transfer between Cat and the underlying electrode, which attributed to the synergistic effect of graphene-NH2 and AuNPs. The resultant bioelectrode retained its biocatalytic activity and offered fast and sensitive H2O2 quantification. Under the optimized experimental conditions, hydrogen peroxide was detected in the concentration range from 0.3 to 600 ?M with a detection limit of 50 nM at S/N = 3. The biosensor exhibited some advantages, such as short time respond (2 s), ...

British Library Electronic Table of Contents (United Kingdom)

Bacterial cellulose was produced by Acetobacter xylinum (strain TISTR 975). Bacterial cellulose is an interesting material for using as a wound dressing since it provides moist environment to a wound resulting in a better wound healing. However, bacterial cellulose itself has no antimicrobial activity to prevent wound infection. To achieve antimicrobial activity, silver nanoparticles were impregnated into bacterial cellulose by immersing bacterial cellulose in silver nitrate solution. Sodium borohydride was then used to reduce the absorbed silver ion (Ag+) inside of bacterial cellulose to the metallic silver nanoparticles (Ag0). Silver nanoparticles displayed the optical absorption band around 420nm. The red-shift and broadening of the optical absorption band was observed when the mole rat...

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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.

British Library Electronic Table of Contents (United Kingdom)

Polycrystalline ZnO doped with Mn (5 and 10at%) was prepared by the co-precipitation method. The effect of Mn doping on the photocatalytic, antibacterial activities and the influence of doping concentration on structural, optical properties of nanoparticles were studied. Structural and optical properties of the particles elucidated that the Mn2+ ions have substituted the Zn2+ ions without changing the Wurtzite structure of ZnO. The optical spectra showed a blue shift in the absorbance spectrum with increasing dopant concentration. The photocatalytic activities of ZnO powders were evaluated by measuring the degradation of methylene blue (MB) in water under the UV region. It was found that undoped ZnO bleaches MB much faster than manganese doped ZnO upon its exposure to the U...

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A piezoelectric biosensor substrate useful for immobilizing biomolecules in an oriented manner on the surface of a piezoelectric sensor has a ladder polymer of polyacrylonitrile. To make the substrate, a solution of an organic polymer, preferably polyacrylonitrile, is applied to the surface of a piezoelectric sensor. The organic polymer is modifying by heating the polymer in a controlled fashion in air such that a ladder polymer is produced which, in turn, forms the attachment point for the biomolecules comprising the piezoelectric biosensor. 3 figs.

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.

International Nuclear Information System (INIS)

Focused ion beam (FIB) milling techniques are presented aiming at the manipulation of both tin dioxide (SnO_2) inverted opals and polystyrene (PS) direct opals. Different SnO_2 opals are considered in order to estimate the regularity of their bulk after the production. A SnO_2 mesoporous monolith is FIB micromachined to make it suitable for optical applications. PS direct opals are structured by FIB milling at different scales. Ordered arrays of PS opals are modified by selectively removing a single sphere. In performing this task, we discuss the effects on the FIB milling due to the gas-assisted enhanced etching and to the binding of the nearest neighbours. Techniques to achieve imaging of PS opals in absence of a conductive coating are also brought up. Furthermore, isolated PS spheres are drilled with or without enhanced etching in order to produce controlled defects on them. The FIB-assisted manipulations we show may find potential applications in the field of ...

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The novel optical, electronic, and/or magnetic properties of metal and semiconductor nanoparticles have resulted in extensive research on new methods for their preparation. An ideal preparation method would allow the particle size, size distribution, crystallinity, and particle shape to be easily controlled, and would be applicable to a wide variety of material systems. Numerous preparation methods have been reported, each with its inherent advantages and disadvantages; however, an ideal method has yet to emerge. The most widely applied methods for nanoparticle preparation include the sonochemical reduction of organometallic reagents,(1&2) the solvothermal method of Alivisatos,(3) reactions in microemulsions,(4-6) the polyol method (reduction by alcohols),(7-9) and the use of polymer and solgel materials as hosts.(10-13) In addition to these methods, there are a variety of methods that take advantage of the unique ...

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The CaWO{sub 4}:Ln{sup 3+} SiO{sub 2} (Ln=Tb, Dy and Ho) nanoparticles were synthesized via a combustion process at 800 {sup o}C, 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{sub 4}{sup 2-} groups and the PL spectra showed the WO{sub 4}{sup 2-} wide excitation band, broad emission band of WO{sub 4}{sup 2-} and characteristic emissions of Ln{sup 3+} ions. The average particle sizes were determined by TEM, which are about 50 nm.

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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 ...

British Library Electronic Table of Contents (United Kingdom)

Yb3+?Tm3+ codoped tellurite glasses containing silver nanoparticles (NPs) were synthesized and characterized using transmission electron microscopy and optical techniques. The samples? composition and the nucleation of NPs were investigated using electron diffraction and energy dispersive spectroscopy. For the optical experiments, the samples were excited using a diode laser operating at 980?nm, in resonance with the Yb3+ transition 2F7/2?2F5/2. Photoluminescence (PL) bands corresponding to Tm3+ transitions were observed at 480, 650, and 800?nm due to the Yb3+? Tm3+ energy transfer. PL enhancement was achieved by heat-treatment of the samples at 325?C during different time intervals. The growth of the PL bands correlates with the increase of the silver NPs concentration. The relevant mecha...

UK PubMed Central (United Kingdom)

Integration of solid-state biosensors and lipid bilayer membranes is important for membrane protein research and drug discovery. In these sensors, it is critical that the solid-state sensing...Full Text Available

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Energy Technology Data Exchange (ETDEWEB)

Nanoparticles represent versatile building blocks in material science and nanotechnology. Thereby, the defined assembly of nanostructures (13 and 56 nm in diameter, respectively) is of significant importance. Short DNA sequences can be bound to the nanoparticle surface thus enabling highly specific DNA hybridization-driven events that direct the formation of nanoparticle constructs.In this paper, examples for the defined formation of gold nanoparticle constructs are demonstrated. In addition, gold-silver core-shell nanoparticles are introduced as further building blocks for the hybridization-controlled formation of nanoparticle constructs.

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 crystals grown over 40 years ago and evaluated ...

International Nuclear Information System (INIS)

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 nanoparticles.

Science.gov (United States)

Simple and low cost biosensor based on screen-printed electrode for sensitive detection of some alkylphenols was developed, by entrapment of HRP in a nanocomposite gel based on single-walled carbon nanotubes (SWCNTs) and 1-butyl-3-methylimidazolium hexafluorophosphate ([BMIM][PF(6)]) ionic liquid. Raman and FTIR spectroscopy, CV and EIS studies demonstrate the interaction between SWCNTs and ionic liquid. The nanocomposite gel, SWCNT-[BMIM][PF(6)] provides to the modified sensor a considerable enhanced electrocatalytic activity toward hydrogen peroxide reduction. The HRP based biosensor exhibits high sensitivity and good stability, allowing a detection of the alkylphenols at an applied potential of -0.2V vs. Ag/AgCl, in linear range from 5.5 to 97.7?M for 4-t-octylphenol and respectively, between 5.5 and 140?M for 4-n-nonylphenol, with a response time of about 5s. The detection limit was 1.1?M for 4-t-octylphenol, and respectively 0.4?M for ...

British Library Electronic Table of Contents (United Kingdom)

We report a solution-phase synthetic route to copper nanoparticles with controllable size and shape. The synthesis of the nanoparticles is achieved by the reduction of copper(II) salt in aqueous solution with hydrazine under air atmosphere in the presence of poly(acrylic acid) (PAA) as capping agent. The results suggest that the pH plays a key role for the formation of pure copper nanoparticles, whereas the concentration of PAA is important for controlling the size and geometric shape of the nanoparticles. The average size of the copper nanoparticles can be varied from 30 to 80 nm, depending on the concentration of PAA. With a moderate amount of PAA, faceted crystalline copper nanoparticles are obtained. The as-synthesized copper nanoparticles appear red in color and are stable for weeks, ...

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DEFF Research Database (Denmark)

Udgivelsesdato: 2008/5

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Research at the interface between biomolecules and inorganic nanocrystals has resulted in a great number of new discoveries. In part this arises from the synergistic duality of the system: biomolecules may act as self-assembly agents for organizing inorganic nanocrystals into functional materials; alternatively, nanocrystals may act as microscopic or spectroscopic labels for elucidating the behavior of complex biomolecular systems. However, success in either of these functions relies heavily uponthe ability to control the conjugation and assembly processes.In the work presented here, we first design a branched DNA scaffold which allows hybridization of DNA-nanocrystal monoconjugates to form discrete assemblies. Importantly, the asymmetry of the branched scaffold allows the formation of asymmetric2assemblies of nanocrystals. In the context of a self-assembled device, this can be considered a step toward the ability to engineer functionally distinct inputs and outputs.Next we develop an ...

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)

Recent research has shown that biologically inspired approaches to materials synthesis and self-assembly, hold promise of unprecedented atomic level control of structure and interfaces. In particular, the use of organic molecules to control the production of inorganic technological materials has the potential for controlling grain structure to enhance material strength; controlling facet expression for enhanced catalytic activity; and controlling the shape of nanostructured materials to optimize optical, electrical and magnetic properties. In this work, we use organic molecules to modify silver crystal shapes towards understanding the metal-organic interactions that lead to nanoparticle shape control. Using in situ electrochemical AFM (EC-AFM) as an in situ probe, we study the influence of a cationic surfactant cetyltrimethylamminobromide (CTAB) on Ag growth during electrochemical deposition on Ag(100). The results show that the organic ...

Science.gov (United States)

... lasers, model switched optical memory elements ... Optical RS flip flop, Acousto-optic switches. ... FLOP CIRCUITS, OPTICAL SWITCHING, NOR GATES ...

British Library Electronic Table of Contents (United Kingdom)

Nanoparticle metal oxides offer a wide variety of potential applications in medicine due to the unprecedented advances in nanobiotechnology research. In this work, the effect of zinc oxide (ZnO) nanoparticles prepared by mechano-chemical method on the antibacterial activity of different antibiotics was evaluated using disk diffusion method against Staphylococcus aureus and Escherichia coli. The average size of ZnO nanoparticles was between 20 nm and 45 nm. Although ZnO nanoparticles (500 mg/disk) decreased the antibacterial activity of amoxicillin, penicillin G, and nitrofurantoin in S. aureus, the antibacterial activity of ciprofloxacin increased in the presence of ZnO nanoparticles in both test strains. A total of 27% and 22% increase in inhibition zone areas was observed for ciprofloxac...

British Library Electronic Table of Contents (United Kingdom)

Novel fluoroalkyl end-capped vinyltrimethoxysilane oligomeric nanoparticles were prepared by the hydrolysis of the corresponding oligomer under alkaline conditions. The size of fluorinated nanoparticles thus obtained is of submicrometer levels and is not sensitive to the refractive indices of a variety of solvents; however, the turbidity of the dispersed fluorinated nanoparticles is extremely sensitive to the refractive indices of these solvents. In particular, the solvents of which the refractive indices are from 1.378 to 1.408 were found to afford the transparent colorless dispersed particle solutions. More interestingly, the modified glass surface treated with fluorinated nanoparticles exhibited a completely superhydrophobic characteristic (a water contact angle: 180?) with a nonwetting...

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...

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The objectives of this study are to make a biosensor on a trial basis which can instantaneously measure the nitrogen in wastewater, and to develop a wastewater treatment system which is capable of on-line measurement and controlling. The system provides easier operational control relating to such a high efficient treatment as the removal of nitrogen content in wastewater, serving as a solution to the eutrophication problem. It can be applied also to the analysis of fertilizer components for agriculture. Ammonia oxidizing bacteria were immobilized with cellulose acetate film, which is mounted on a diaphragm type oxygen electrode to make a sensor, and its responsibility was studied. The gradient is slow in high concentration but sharp in low concentration, and it seems possible to use it for the measurement for less than 20 ppm nitrogen concentration. The dependence of the sensor including electrodes and activity of bacteria on temperature is large, and the ...

UK PubMed Central (United Kingdom)

To capitalize on the response of tumor cells to ionizing radiation, we developed a controlled-release nanoparticle drug delivery system using a targeting peptide that recognizes a radiation-induced...Full Text Available

UK PubMed Central (United Kingdom)

The purpose of this study was to synthesize biocompatible polyvinylpyrrolidone (PVP)-coated iron oxide (PVP-IO) nanoparticles and to evaluate their efficacy as a magnetic resonance imaging (MRI)...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.

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We report a templated-synthetic approach based on apoferritin to prepare radionuclide nanoparticle (NP) conjugates. Non-radioactive yttrium (89Y) was used as model target and surrogate for radioyttrium (90Y) to prepare the nanoparticle conjugate. The center cavity and multiple channel structure of apoferritin offer a fast and facile method to precipitate yttrium phosphate by diffusing yttrium and phosphate ions into the cavity of apofrritin, resulting a core-shell nanocomposite. The yttrium phosphate/apoferritin nanoparticle was functionalized with biotin for further application. The synthesized nanoparticle was characterized by transmission electron microscopy (TEM) and x-ray photoelectron spectroscopy (XPS). We found that the resulting nanoparticles were uniform in size, with a diameter of around 8 nm. We tested the pre-targeting capability of the biotin-modified yttrium ...

Science.gov (United States)

A novel drug delivery system for the treatment of brain tumors was formulated by methotrexate (MTX)-loaded polymeric nanoparticles (NPs) based on Glycol chitosan (GCS) and Dextran sulfate (DS). The physicochemical properties of resulting particles were investigated, evidencing the contribution of these nanoparticles for brain targeting. In vitro release of MTX was also evaluated. The GCS-DS nanoparticles have been developed based on the modulation of ratio show promise as a system for controlled delivery of the drug to the brain. PMID:21782844

International Nuclear Information System (INIS)

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

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

Science.gov (United States)

... the application of an acousto- optical tunable filter ... Couplers for Large Switch-Array Applications ... Symmetric Integrated Optic X Junction," Electronics ...

Energy Technology Data Exchange (ETDEWEB)

Nanoparticles of silver halides have been prepared by mixing silver halide powder with a single liquid phase consisting of an ionic liquid, isooctane, n-decanol and water. Much higher nanoparticle concentrations may be formed with ionic liquids using this new simple method than are found with conventionally applied surfactants. This method also emphasizes the applicability of ionic liquids as versatile components in microemulsions and as solvents for the synthesis of nanomaterials. The effect on the nanoparticles of changing the composition of the liquid mixtures and the nature of the ionic liquid is analysed. High nanoparticle concentrations were only found with chloride based ionic liquids, indicating the importance of the ionic liquid anion in the mechanism of the reaction.

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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...

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 Science & Technology Center (ISTC)

Photochromes for New Generation of Highly Efficient Computers with Three Dimensional (3D) Optical Memory

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We describe the synthesis and characterization of superparamagnetic iron oxide nanoparticle based heavy metal sorbents with various surface chemistries that demonstrate an excellent affinity for the separation of heavy metals in contaminated water systems (i.e. spiked Columbia river water). The magnetic nanoparticle sorbents are prepared from an easy to synthesize iron oxide precursor, followed by a simple, one-step ligand exchange technique to introduce the organic surface functionality of interest chosen to target either specific or broader classes of heavy metals. Functionalized superparamagnetic nanoparticles are excellent sorbent materials for the extraction of heavy metal contaminants from environmental and clinical samples since they are easily removed from the media once bound to the contaminant by simply applying a magnetic field. These engineered magnetic nanoparticle sorbents have an ...

British Library Electronic Table of Contents (United Kingdom)

Abstract Bioluminescent bacteria have been used for many years for biotoxicological analysis. One of the main concerns with this microorganism is the low experimental repeatability when subjected to external factors. The aim of the present study was to obtain accurate, sensitive, and repeatable measurements with stable signals (during the detection and over days) for application in a water-analysis device for the detection of pollutants. Growth conditions were tested and optimized. An optimal freeze-drying procedure for the constitutive bioluminescent bacteria Vibrio fischeri and Photobacterium phosphoreum was developed. The luminescence stability after rehydration was also investigated. Freeze drying was found to be a critical process in survival and signal stability of luminescent bacter...

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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)

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 ...

International Nuclear Information System (INIS)

Single-crystalline cadmium selenide nanoparticles were obtained using high-temperature solution phase synthesis (HTSPS) synthesis. X-Ray powder diffraction and transmission electron microscopy were used to confirm the crystallinity and morphology of the resulting nanoparticles. To study the action of CdSe on antioxidant activity, we selected two biotechnological important strains of microalgae: cyanobacteria Spirulina platensis and red microalgae Porphyridium cruentum. In the case of Porphyridium cruentum, the obtained results demonstrated an increase in the productivity. For Spirulina platensis, the presence of the compound in the cultivating medium decreased the productivity of cyanobacteria.

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Electron paramagnetic resonance was used to investigate surface-coated magnetite-based magnetic fluids doped with TEMPOL. Two magnetic fluid samples, having magnetite nanoparticles with average diameter of 94 A and coated with different coating layers (lauric acid plus ethoxylated polyalcohol in one case and oleoylsarcosine in the other case), were doped with TEMPOL (6 mM and pH 7.4) and investigated as a function of the nanoparticle concentration. The resonance field and the resonance linewidth both scale linearly with the nanoparticle concentration.

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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.

International Nuclear Information System (INIS)

We have fabricated nanometer-spaced electrodes on electron-transparent silicon nitride membranes. A thin Cr/Au layer is evaporated on the backside of the membrane which serves as a gate electrode. Using these devices, we have performed three-terminal electron transport measurements on gold nano-particles at liquid helium temperature. Coulomb Blockade features have been observed and the capacitance to the gate has been extracted. After transport measurements, the Cr/Au back gate is removed and the devices are inspected with a transmission-electron microscope (TEM). TEM inspection reveals the presence of a few nano-particles in the nanogap, which is in agreement with the transport measurements. In addition, the nano-particle size as observed by TEM coincides with the one estimated from the gate capacitance value.

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A micellar method has been used to prepare silver-coated cobalt (Co-Ag) nanoparticles. The synthesized particles have been deeply characterized by several methods, i.e., XRD, UV-Vis, TEM, XPS, and electrochemical techniques. There is every indication that the obtained particles show a truly core-shell structure. All the nanoparticles obtained under different conditions are in the size range 3-5 nm. High-resolution TEM (HRTEM), Fast Fourier Transformation (FFT), and Selected Area Electron Diffraction (SAED) indicated that the presence of hcp-Co and fcc-Ag, in which cobalt is located in the central area; meanwhile silver is at the edges of the nanoparticle. The absorption band of the Co-Ag colloid shifts to a longer wavelength and broadens relative to that of pure silver colloid. Voltammetric characterization allowed to determine the coverage of the cobalt core.

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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 ...

Science.gov (United States)

... M(TH) in applied magnetic fields up to ± 7 T and for temperatures ranging from 2 to 300 K. The superparamagnetic (SPM) behavior of these metallic ...

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The cytotoxicity of 15-nm and 46-nm silica nanoparticles was investigated by using crystalline silica (Min-U-Sil 5) as a positive control in cultured human bronchoalveolar carcinoma-derived cells. Exposure to 15-nm or 46-nm SiO_2 nanoparticles for 48 h at dosage levels between 10 and 100 #mu#g/ml decreased cell viability in a dose-dependent manner. Both SiO_2 nanoparticles were more cytotoxic than Min-U-Sil 5; however, the cytotoxicities of 15-nm and 46-nm silica nanoparticles were not significantly different. The 15-nm SiO_2 nanoparticles were used to determine time-dependent cytotoxicity and oxidative stress responses. Cell viability decreased significantly as a function of both nanoparticle dosage (10-100 #mu#g/ml) and exposure time (24 h, 48 h, and 72 h). Indicators of oxidative stress and cytotoxicity, including total reactive oxygen species (ROS), ...

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 ...

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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...

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... The acousto-optic device have a 30 MHz 1 ... coherent systems including compact non-coherent optical ... a relatively simple phase switching approach. ...

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... silicon oxide (BSO), bismuth germanium oxide (BGO), and bismuth titanium oxide (BTO). These crystals are electro-optic, optically active, ...

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PMID:19829557

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BackgroundNew technology allows more precise definition of structural alterations of all retinal layers although it has not been used previously in cases of optic...Full Text Available

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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

Environmental Research Database

Objectives1) To establish a protocol for transfection of immortalised type I cells with SiRNA and its effect on cell viability; 2) To optimise silencing of genes involved in endocystosis using SiRNA and confirm successful transfection with western blotting; 3) To investigate the effect of gene silencing on uptake of flourescently-labelled latex nanoparticles.DescriptionTo investigate the mechanisms of particle uptake.

Environmental Research Database

DescriptionNanotechnology is rapidly expanding, and is forecast to become a trillion dollar industry in the near future. It is inevitable that as nanotechnology applications increase, increasing amounts of manufactured nanoparticles (mNPs) will be released into the environment. The environmental and human health implications of the release of most of the huge range of possible particle types are as yet largely unknown, but in the context of groundwaters, apart from implications for the drinking of contam [continued...

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... Accession Number : ADA152970. Title : Optical Phenomena in Computer Vision,. Corporate Author : ROCHESTER UNIV ...

Science.gov (United States)

... Acousto-optic programmable dispersive filters (AOPDF) have been developed for optical signal processing, polarization switching in lasers, and ...

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Using {gamma}-irradiation-induced reduction in the field of a {sup 60}Co {gamma}-ray source, colloidal silver and gold nanoparticles were prepared from their corresponding metal salts in aqueous solution and compared with those by chemical reduction. The radiation-based method provided silver nanoparticles with higher concentration and narrower size distribution than those obtained by chemical reduction method while there was no significant difference between the two strategies for the preparation of gold nanoparticles. {gamma}-Irradiation of 1.0 x 10{sup -3} M AgNO{sub 3} solution resulted in nearly 100 times more highly concentrated silver colloids than those by citrate reduction. Furthermore, the radiation method could lead to more highly concentrated silver colloids by simply increasing the concentration of AgNO{sub 3} solution up to 2.0 x 10{sup -2} M. The two metal nanoparticles prepared by the ...

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There has been considerable interest in producing and studying nanoparticle materials because of the effect of size on their structure, physical and chemical structure. Most studied nanoparticle semiconductors belong to the II-VI group, as they are relatively easy to synthesize and are generally prepared as particulates or in thin film form. Among II-VI compounds, CdS is one of the most studied materials. There are different ways to synthesize CdS nanoparticles such as colloidal particles, chemical decomposition, sol-gel, gas evaporation, magnetron sputtering, electrostatic deposition, and etc. {gamma}-irradiation is one of the effective methods for synthesis of nanomaterials. These nonomaterials have been extensively used in the preparation of nanocrystalline metals, metal oxides, and metal-polymer composites. However, The preparation of CdS nanoparticle and CdS/ polyacrylonitrile nanocomposite by ...

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 ...

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In the present dissertation, a hierarchical multiscale approach for modeling FePt nanoparticles by atomistic computer simulations is developed. By describing the interatomic interactions on different levels of sophistication, various time and length scales can be accessed. Methods range from static quantum-mechanic total-energy calculations of small periodic systems to simulations of whole particles over an extended time by using simple lattice Hamiltonians. By employing these methods, the energetic and thermodynamic stability of non-crystalline multiply twinned FePt nanoparticles is investigated. Subsequently, the thermodynamics of the order-disorder transition in FePt nanoparticles is analyzed, including the influence of particle size, composition and modified surface energies by different chemical surroundings. In order to identify processes that reduce or enhance the rate of transformation from the disordered to the ...

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In this study, nanoparticle penetration was measured with a wide range of filter media using silver nanoparticles from 3 nm to 20 nm at three different face velocities in order to define nanoparticle filtration characteristics of commercial fibrous filter media. The silver particles were generated by heating a pure silver powder source via an electric furnace with a temperature of 870 deg. C, which was found to be the optimal temperature for generating an adequate amount of silver nanoparticles for the size range specified above. After size classification using a nano-DMA, the particle counts were measured by an Ultrafine Condensation Particle Counter (UCPC) both upstream and downstream of the test filter to determine the nanoparticle penetration for each specific particle size. Particle sampling time continued long enough to detect more than 10{sup 5} counts at the upstream and 10 ...

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...

British Library Electronic Table of Contents (United Kingdom)

Microgel-clay composite particles were prepared by one-step surfactant-free precipitation polymerization. Laponite nanoparticles present in the reaction mixture become encapsulated during the microgel formation process. Microgel-clay composites based on poly(N-vinylcaprolactam-co-acetoacetoxyethyl methacrylate) containing different amount of incorporated clay nanoparticles were synthesized. The clay content was varied from 2 wt% to 18 wt%. The extremely high incorporation efficiency of the clay nanoparticles into microgels was detected. The size of the hybrid microgels was decreased from 700 nm to 100 nm by increase of the clay concentration in the reaction mixture. Obtained hybrid microgels exhibit negative surface charge and excellent colloidal stability. Microgel-clay composite particle...

British Library Electronic Table of Contents (United Kingdom)

Cellulose whiskers and microfibrillated cellulose (MFC) were extracted from the rachis of date palm tree and characterized. These cellulosic nanoparticles were used as reinforcing phase to prepare nanocomposite films using latex of natural rubber as matrix. These films were obtained by the casting/evaporation method. The properties of the ensuing nanocomposite films were investigated using differential scanning calorimetry, toluene and water uptake experiments, dynamic mechanical analysis and tensile tests. The stiffness of the natural rubber was significantly increased above its glass-rubber transition temperature upon nanoparticles addition. The reinforcing effect was shown to be higher for nanocomposites with MFC compared to whiskers. It was ascribed to the higher aspect ratio and possi...

British Library Electronic Table of Contents (United Kingdom)

Iron nanoparticles were produced using extracts of green tea leaves (GT-Fe NPs). The materials were characterized using TEM, SEM/EDX, XPS, XRD, and FTIR techniques and were shown to contain mainly iron oxide and iron oxohydroxide. The obtained nanoparticles were then utilized as a Fenton-like catalyst for decolorization of aqueous solutions containing methylene blue (MB) and methyl orange (MO) dyes. The related experiments investigated the removal kinetics and the effect of concentration for both MB and MO. The concentrations of dyes in aqueous solution were monitored using ultraviolet-visible (UV-vis) spectroscopy. The results indicated fast removal of the dyes with the kinetic data of MB following a second order removal rate, while those of MO were closer to a first order removal rate. T...

British Library Electronic Table of Contents (United Kingdom)

A supercritical fluid-based method is proposed to produce coenzyme Q10 (CoQ10) nanoparticles. First, CoQ10/polyethylene glycol 6000 composite particles are prepared by a modified PGSS (particles from gas-saturated solutions) process with controlling the flow rate of the gas-saturated solution. Then, CoQ10 nanoparticles are obtained by dissolving the composite particles into water. The effect of experimental variables of the modified PGSS process, including pressure, temperature, flow rate of the gas-saturated solution, and mass fraction of CoQ10, on the CoQ10 particle size and particle size distribution was investigated. Results show that CoQ10 slurry product with a median diameter of 190nm and yield of 89.8% can be prepared at an optimum condition (operating pressure of 25MPa, operating t...

British Library Electronic Table of Contents (United Kingdom)

The core-shell luminol-doped SiO2 nanoparticles were synthesized and immobilized on the surface of chitosan film coating graphite electrode by the self-assembled technique. Then, a novel electrogenerated chemiluminescence (ECL) sensor for pyrogallol was developed based on its ECL enhancing effect for the core-shell luminol-doped silica nanoparticles. The ECL analytical performances and the sensing mechanism of this ECL sensor for pyrogallol were investigated in detail. The corresponding results showed that: compared with the conventional ECL reaction procedures by luminol ECL reaction system, the electrochemical (EC) reaction of pyrogallol and its subsequent chemiluminescence (CL) reaction occurred in the different spatial region whilst offering a high efficiency to couple the EC with the ...

Science.gov (United States)

An on-line cell disruption system for at-line monitoring of the intracellular concentration of recombinant human superoxide dismutase (rhSOD) in a genetically modified Escherichia coli strain, HMS174(DE3) (pET11a/rhSOD), in bioreactor cultivations is described. The sampled bacteria were disrupted on-line by rapid mixing with a nonionic detergent. The recombinant protein content of the lysed bacterial sample was quantitated by a subsequent surface plasmon resonance biosensor with a specific monoclonal antibody. Extraction efficiency of the monitoring system was optimized with respect to the flow rate ratio of the cell suspension and the detergent at relevant cell densities with the aim to attain rapid monitoring. Monitoring was demonstrated for a shake flask culture and a glucose-limited fed-batch cultivation. The results are compared with a traditional enzyme-linked immunosorbent assay method showing a correlation coefficient of R2 = 0.97. Extraction efficiency of ...

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.

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 ...

UK PubMed Central (United Kingdom)

Severe acute respiratory syndrome (SARS) is an infectious disease caused by a novel coronavirus that cost nearly 800 lives. While there have been no recent outbreaks of the disease, the threat...Full Text Available

British Library Electronic Table of Contents (United Kingdom)

The removal of Ni(II) from aqueous solution by magnetic nanoparticles prepared and impregnated onto tea waste (Fe3O4-TW) from agriculture biomass was investigated. Magnetic nanoparticles (Fe3O4) were prepared by chemical precipitation of a Fe^2^+ and Fe^3^+ salts from aqueous solution by ammonia solution. These magnetic nanoparticles of the adsorbent Fe3O4 were characterized by surface area (BET), Scanning Electron Microscopy (SEM), Transmission Electron Microscopy (TEM) and Fourier Transform-Infrared Spectroscopy (FT-IR). The effects of various parameters, such as contact time, pH, concentration, adsorbent dosage and temperature were studied. The kinetics followed is first order in nature, and the value of rate constant was found to be 1.90x10^-^2min^-^1 at 100mgL^-^1 and 303K. Removal ef...

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

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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.)

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Papers are presented in the areas of: Medical Technologies; Non-Destructive Evaluation; Applications of Signal/Image Processing; Laser Guide Star and Adaptive Optics; Computational Electromagnetic, Acoustics and Optics; Micro-Impulse Radar Processing; Optical Applications; TANGO Space Shuttle.

UK PubMed Central (United Kingdom)

An optical flow gradient algorithm was applied to spontaneously forming networks of neurons and glia in culture imaged by fluorescence optical microscopy in order to map functional calcium signaling...Full Text Available

UK PubMed Central (United Kingdom)

PurposeTo determine the effects of age on global and sectoral peripapillary retinal nerve fiber layer (RNFL), macular thicknesses and optic nerve head (ONH) parameters...Full Text Available

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A bottom-up approach is used here to combine carbon nanotubes synthesized by CVD and organically capped platinum nanoparticles electrocatalyst exhibiting a direct electrochemical activity towards oxygen reduction. Both nano-objects are handled in liquid suspension and are associated together in a controlled way. The nanocomposite liquid dispersions can be precisely controlled in terms of platinum nanoparticles to carbon nanotubes weight ratios (NP/NT) which correspond to different coverages of nanotubes by nanoparticles. Electrodes with low to ultra-low platinum loadings can then be prepared on porous fuel cell carbon supports by filtration. The direct electrochemical activity towards aqueous oxygen reduction reaction (ORR) of electrodes with platinum loadings ranging from about 1 to 60 {mu}g/cm{sup 2} is reported without any activation step in order to keep the features of the nanoparticles intact. ...

Science.gov (United States)

... electronic feedback system' connected to a Q switch ... The use of acousto-optic (AO) beam steering devices for BMDO (SDI) applications is very ...

Science.gov (United States)

An analysis is made of the basic principles and methods of construction of integrated optical circuits (IOC) for data processing, which are optical waveguide processors in the integrated form. A classification is provided of IOC in accordance with the nature of the input connections to optical components and in accordance with their intended function. An analysis is made of the current status of research and development of analog IOC for handling analog and digital signals, IOC for computing technology, and switching IOC. A detailed analysis is made of IOC with different functions in data processing: spectrum analyzers and correlators, analog-digital converters, circuits for identification of data sets and for encoding of signals, threshold and multistable circuits, logic and arithmetic units, and switching arrays. Descriptions are given of IOC for optically controlled data handling: bistable purely ...

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... switching off all the pixels causes all the spectrum lines to disappear (top of Figure 6), next, that switching off one ... Acousto-optic spectrum analyser ...

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... a rotating mirror Q-switch or an acousto-optic Q-switch. The former ... Q-switch up to 2000 pps. The Q-switched output bean, is predominantly ...

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Jan 22, 2004 ... Training and Professional Development Leadership Development Program. GSFC Leadership Development Program Positions. Cryo-Optical ...

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Described herein is an optical probe (120) for use in characterizing surface defects in wafers, such as semiconductor wafers. The optical probe (120) detects laser light reflected from the surface (124) of the wafer (106) within various ranges of angles. Characteristics of defects in the surface (124) of the wafer (106) are determined based on the amount of reflected laser light detected in each of the ranges of angles. Additionally, a wafer characterization system (100) is described that includes the described optical probe (120).

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This book examines the nonlinear optical properties of laser materials. The physical radiation effects on laser materials are also considered. Topics considered include: nonlinear optical properties; nonlinear and harmonic generation materials; two-photon absorption; nonlinear refractive index; stimulated Raman scattering; radiation damage; crystals; and glasses.

International Nuclear Information System (INIS)

In this study, a miniature fiber-optic radiation detector has been developed using a water-equivalent organic scintillator for electron beam therapy dosimetry. Usually, two kinds of light signals such as fluorescent and Cherenkov lights are generated in a fiber-optic radiation detector when a high-energy electron beam is irradiated. The fluorescent light signal is produced in the scintillator and is transmitted through a plastic optical fiber to a remote light-measuring device such as a PMT or a photodiode. The Cherenkov light could be also produced in the plastic optical fiber itself and be detected by a light-measuring device. Therefore, it could cause problems or limit the accuracy of the detection of a fluorescent light signal that is proportional to dose. The objectives of this study are to measure, characterize and eliminate Cherenkov light generated in a plastic optical fiber ...

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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 ...

International Nuclear Information System (INIS)

Because of limitation on neutron-incident data, it is difficult to obtain global optical model potential for neutrons. In contrast, there are some global optical model potentials for proton in detail. It is interesting to convert the proton-incident global optical potentials into neutron-incident ones. In this study we introduce (N-Z)/A dependent symmetry potential terms into the global proton-incident optical potentials, and then obtain neutron-incident ones. The neutron potentials reproduce total cross sections in an acceptable degree. However, a comparison with potentials proposed by other authors brings about a confused situation in the sign of the symmetry terms. (author).

International Nuclear Information System (INIS)

A fiber optic feedthrough module which comprises a metal sleeve, a fiber optic element extending through the sleeve in spaced relation thereto, and a tandem series of centrally-apertured mating annular sealant bodies of thermoplastic material surrounding the fiber optic element and compressed between it and the sleeve. The module is made by first providing a loose subassembly of a plurality of individual but interfitting sealant bodies on the fiber optic element and then inserting this subassembly into a metal sleeve, following by swaging the whole assembly which eliminates clearances and provides sealed interfaces between the various contacting components. (author).

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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 ...

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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}.

International Nuclear Information System (INIS)

Topographic and optical patterns have been fabricated in a-SiC films with a focused high-energy (1 MeV) H"+ and He"+ ion beam and examined with near-field techniques. The patterns have been characterized with atomic force microscopy and scanning near-field optical microscopy to reveal local topography and optical absorption changes as a result of the focused high-energy ion beam induced modification. Apart of a considerable thickness change (thinning tendency), which has been observed in the ion-irradiated areas, the near-field measurements confirm increases of optical absorption in these areas. Although the size of the fabricated optical patterns is in the micron-scale, the present development of the technique allows in principle writing optical patterns up to the nanoscale (several tens of nanometers). The observed values of the optical ...

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Reduction of silver myristate (AgMy) under mild thermal reaction conditions in a dipolar aprotic solvent i.e. N, N-dimethylformamide (DMF) has been carried out. UV-visible absorption measurements of dried and re-dispersible brown flocculants showed broad features of surface plasmon resonance (SPR) due to silver nanoparticles. The freshly isolated particles showed absorption bands at 414 and 485 nm, respectively, due to inter-particle coupling or clustering of silver ions and silver atoms. X-ray diffraction (XRD) pattern of fcc zero-valent silver resulted in crystallite size of about 10 nm. Scanning electron microscopy (SEM) revealed formation of rod shaped silver with increasing reaction temperature. Thermal analysis (TGA) showed about 10% weight loss due to organic capping.

Energy Technology Data Exchange (ETDEWEB)

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)

Alzheimer's disease (AD) is a neurodegenerative disorder for which the research of new treatments is highly challenging. Since the fibrillogenesis of amyloid-b peptide 1-42 (Ab1-42) peptide is considered as a major cause of neuronal degeneration, specific interest has been focused on aromatic molecules for targeting this peptide. In this paper, the synthesis of selegiline-functionalized and fluorescent poly(alkyl cyanoacrylate) nanoparticles (NPs) and their evaluation for the targeting of the Ab1-42 peptide are reported. The synthetic strategy relied on the design of amphiphilic copolymers by tandem Knoevenagel-Michael addition of cyanoacetate derivatives, followed by their self-assembly in aqueous solutions to give the corresponding NPs. Different cyanoacetates were used: (i) hexadecyl cy...

CERN Document Server

We report on the magnetic hyperthermia properties of chemically synthesized ferromagnetic 11 and 16 nm Fe(0) nanoparticles of cubic shape displaying the saturation magnetization of bulk iron. The specific absorption rate measured on 16 nm nanocubes is 1690+-160 W/g at 300 kHz and 66 mT. This corresponds to specific losses-per-cycle of 5.6 mJ/g, largely exceeding the ones reported in other systems. A way to quantify the degree of optimization of any system with respect to hyperthermia applications is proposed. Applied here, this method shows that our nanoparticles are not fully optimized, probably due to the strong influence of magnetic interactions on their magnetic response. Once protected from oxidation and further optimized, such nano-objects could constitute efficient magnetic cores for biomedical applications requiring very large heating power.

British Library Electronic Table of Contents (United Kingdom)

AbstractBackground In recent years nano-metaloxides which easily penetrate into the cells with special interest due to their higher chemical reactivity as compared to that of similar materials in the bulk form. Of particular interest are nano-TiO2 and ZnO, which have been widely used for their bactericidal and anticancerous properties. Purpose The aim of the present study was to examine the bactericidal properties of nano-TiO2 and ZnO combined with visible light on S. aureus and S. epidermitis, known for their high prevalence in infected wounds. Study Using the technique of electron-spin resonance (ESR) coupled with spin trapping, we examined the ability of TiO2 and ZnO nanoparticle suspensions in water to produce reactive oxygen species (ROS) with and without visible light irradiation. Th...

British Library Electronic Table of Contents (United Kingdom)

Direct electrochemistry and electrocatalysis of catalase (Cat) was studied based on a nano-composite film consisting of amine functionalized graphene and gold nanoparticles (AuNPs) modified glassy carbon electrode. Graphene was synthesized chemically by Hummers and Offeman method and then was functionalized with amino groups via chemical modification of carboxyl groups introduced on the graphene surface. The nano-composite film showed an obvious promotion of the direct electron transfer between Cat and the underlying electrode, which attributed to the synergistic effect of graphene-NH2 and AuNPs. The resultant bioelectrode retained its biocatalytic activity and offered fast and sensitive H2O2 quantification. Under the optimized experimental conditions, hydrogen peroxide was detected in the...

British Library Electronic Table of Contents (United Kingdom)

Abstract Nanocomposites based on SnO2 with carbon scaffold were used as highly porous anode films on Ni substrates. The films were obtained by in situ deposition of the particles without any binder or excess carbon black avoiding any secondary treatment. Compared to similarly prepared uncoated SnO2 nanoparticles as well as conventionally prepared powder samples the capacity loss of the in situ deposited nanocomposite films is significantly reduced. Thus, this newly developed anode material combined with in situ film formation is a promising approach for high capacity anodes in Li-ion batteries. SEM-micrograph of a SnO2/C nanoparticle film.

British Library Electronic Table of Contents (United Kingdom)

SBA-15 supported nano-scaled copper oxide was synthesized by impregnation method via ultrasonic-assisted route. The removal test from gas mixture containing 0.1?vol.% hydrogen sulfide was carried out over this material at atmospheric conditions. The effects of the chemical nature of copper oxide and the textural properties of the material on removal capacity were studied. The materials before and after the removal test were analyzed by nitrogen adsorption, X-ray diffraction, Transmission Electron Microscope, X-ray photoelectron Spectroscopy, Fourier Transform Infrared Spectrometer and Inductive Coupled Plasma. The results showed that copper species are located predominantly in mesopore channels, existing as copper oxide nanoparticles. Mesopores are active sites for removal reaction. The ou...

British Library Electronic Table of Contents (United Kingdom)

In this work, silver-montmorillonite (Ag-MMT) antimicrobial nanoparticles have been obtained by allowing silver ions from nitrate solutions to replace the Na^+ of natural montmorillonite and then to be reduced by a thermal treatment. Ag-MMT were used as active antimicrobial compounds to improve the shelf life of fresh fruit salad. In order to assess their influence on product shelf life, sensorial and microbiological quality has been monitored during the storage. The microbiological quality was determined by monitoring the principal spoilage microorganisms (mesophilic and psychrotrophic bacteria, coliforms, lactic acid bacteria, yeasts and molds). Additionally, the evolution of sensorial quality was assessed by monitoring color, odor, firmness and product overall quality. The Ag-MMT nanopa...

International Nuclear Information System (INIS)

The optically stimulated luminescent (OSL) radiation dosimeter technically surveys a wide dynamic measurement range and a high sensitivity. Optical fiber dosimeters provide capability for remote monitoring of the radiation in the locations which are difficult-to-access and hazardous. In addition, optical fiber dosimeters are immune to electrical and radio-frequency interference. In this paper, a novel remote optical fiber radiation dosimeter is described. The optical fiber dosimeter takes advantage of the charge trapping materials CaS:Ce, Sm that exhibit OSL. The measuring range of the dosimeter is from 0.1 to 100 Gy. The equipment is relatively simple and small in size, and has low power consumption. This device is suitable for measuring the space radiation dose and also can be used in high radiation dose condition and other dangerous radiation occasions. (authors)

Energy Technology Data Exchange (ETDEWEB)

The accurate measurement of a stress level is one of the most important issues in a stress diagnosis and its measurement could be of great value in clinical medicine. Stress has a potent effect on the spirit and physical condition of an individual. There are various methods available for its measurement. Some of the commonly used techniques for the diagnosis of a stress level include analysis of the body fluids, questionnaire assessments, psychophysiological evaluations and by determining heart rate variability (HRV) of subjects. However, the existing diagnostic methods have several defects like, a low sensitivity, inaccuracy and long of operation time. In this report, we present a diagnostic technology to detect a stress level which is the origin of various diseases. This method can be of great help in providing an early diagnosis through a biosensor and might play a vital role in preventing diseases like hypochondria and hypertension. Majority of the human ...

UK PubMed Central (United Kingdom)

In a new approach to medical computer based education (CBE) students at several U.S. and Canadian health professions schools have been using an optical videodisc under computer control to study basic...Full Text Available

Energy Technology Data Exchange (ETDEWEB)

Optical absorptance spectra of A-15 compounds were taken using a calorimetric technique in the range 0.2 eV to 4.0 eV. Thermomodulation spectra were taken on several A-15 sputtered films.

UK PubMed Central (United Kingdom)

Although ultrasound arrays were exploited in photoacoustic imaging to improve imaging speed, ultrasound-array-based optical-resolution photoacoustic microscopy (OR-PAM) has never been achieved...Full Text Available

UK PubMed Central (United Kingdom)

PurposeTo describe ocular findings for a 34-year-old man with chronic solar retinopathy using high-speed ultrahigh-resolution (UHR) optical coherence tomography (OCT).Full Text Available

UK PubMed Central (United Kingdom)

The utility of a two-photon optical fiber fluorescence probe (TPOFF) for sensing and quantifying tumor fluorescent signals was tested in vivo. Xenograft tumors were developed in athymic mice using MCA207...Full Text Available

UK PubMed Central (United Kingdom)

The issue of beam-induced damage on diffractive hard X-ray optics is addressed. For this purpose a systematic study on the radiation damage induced by a high-power X-ray beam is carried out in both...Full Text Available

UK PubMed Central (United Kingdom)

We present a method to make phantoms of coronary arteries for intravascular optical coherence tomography (IV-OCT). The phantoms provide a calibrated OCT response similar to the layered structure of...Full Text Available

Energy Technology Data Exchange (ETDEWEB)

In an aim to develop photo-responsive composites, the UV photo-reduction of aqueous titanium oxide nanoparticle-graphene oxide (TiO{sub 2}-GO) dispersions (Lambert et al. J Phys. Chem. 2010 113 (46), 19812-19823) was undertaken. Photo-reduction led to the formation of a black precipitate as well as a soluble portion, comprised of titanium oxide nanoparticle-reduced graphene oxide (TiO{sub 2}-RGO). When allowed to slowly evaporate, self assembled titanium oxide nanoparticle-graphene oxide (SA-TiO{sub 2}-RGO) films formed at the air-liquid interface of the solution. The thickness of SARGO-TiO{sub 2} films range from {approx}30-100 nm when deposited on substrates, and appear to be comprised of a mosaic assembly of graphene nanosheets and TiO{sub 2}, as observed by scanning electron microscopy. Raman spectroscopy and X-ray photoelectron spectroscopy indicate that the graphene oxide is only partially reduced in the SA-TiO{sub ...

UK PubMed Central (United Kingdom)

The synthesis of a new kind of magnetic, fluorescent multifunctional nanoparticles (~30 nm in diameter) was demonstrated, where multiple fluorescent CdTe quantum dots (QDs) are covalently linked...Full Text Available

Energy Technology Data Exchange (ETDEWEB)

Stabilized silver particles comprise particles comprising silver, a short-chain capping agent adsorbed on the particles, and a long-chain capping agent adsorbed on the particles. The short-chain capping agent is a first anionic polyelectrolyte having a molecular weight (Mw) of at most 10,000, and the long-chain capping agent is a second anionic polyelectrolyte having a molecular weight (Mw) of at least 25,000. The stabilized silver particles have a solid loading of metallic silver of at least 50 wt %.

International Nuclear Information System (INIS)

Based on theoretical calculations of powder diffraction data it is shown that the assumption of the infinite crystal lattice for small particles is not justified, leads to significant changes of the diffraction patterns, and may lead to erroneous interpretation of the experimental results. An alternate evaluation of diffraction data of nanoparticles, based on the so-called 'apparent lattice parameter', alp, is proposed. (author)

Science.gov (United States)

... Tunable semiconductor lasers are essential components for links employing optical frequency modulation (OFM) for enhanced dynamic range or ...

International Nuclear Information System (INIS)

... Union (INTAS), Brussels (Belgium) Science and Technology Center in Unkraine,

Science.gov (United States)

... Abstract : A COMMERCIALLY AVAILABLE CAMOO4 TUNABLE ACOUSTO- OPTIC FILTER HAS BEEN ... OF THE FILTER CAN BE SWITCHED IN 20 ...

Energy Technology Data Exchange (ETDEWEB)

No abstract prepared.

Science.gov (United States)

... is the sensor that converts incoming photons into a ... with CCD foundries to acquire such a sensor. ... 2007, Journal of Spacecraft and Rockets, 44, 910 ...

Science.gov (United States)

... concentrated on the construction of switches using fiber ... been chosen for a switch realized in ... of these techniques using acousto-optic modulators or ...

Science.gov (United States)

... Thus, 0CM provides the potential to image epithelial tissue with the subcellular resolution needed to assess the pathologic state of tissue. ...

Energy Technology Data Exchange (ETDEWEB)

This book describes the uses, coatings, and fabrication of laser materials. Topics considered include: optical waveguide materials; optical storage materials; holographic recording materials; phase conjunction materials; holographic recording materials; phase conjunction materials; laser crystals; laser glasses; quantum counter materials; thin films and coatings; multilayer dielectric coatings; graded-index surfaces and films; optical materials fabrication; fabrication techniques; fabrication procedures for specific materials.

Energy Technology Data Exchange (ETDEWEB)

A monolithic micromachined waveguide device or devices with low-loss, high-power handling, and near-optical frequency ranges is set forth. The waveguide and integrated devices are capable of transmitting near-optical frequencies due to optical-quality sidewall roughness. The device or devices are fabricated in parallel, may be mass produced using a LIGA manufacturing process, and may include a passive component such as a diplexer and/or an active capping layer capable of particularized signal processing of the waveforms propagated by the waveguide.

Energy Technology Data Exchange (ETDEWEB)

High purity MgAl{sub 2}O{sub 4} spinel specimens irradiated in FFTF-MOTA to very high exposure have been examined by three techniques to determine changes in their optical properties. Significant changes were observed in optical absorption, photoluminescence and radioluminescence.

Energy Technology Data Exchange (ETDEWEB)

Recently there has been growth, in interest in non-equilibrium interaction of half-period long optical pulses with matter. To date the optical pulses have been produced by chopping out a half-period long segment from a longer pulse using a semiconductor switch driven by a femtosecond laser. In this paper we present new methods for producing tunable ultra-short optical pulses as short as half an optical period using a free-electron laser driven by electron bunches with a duration a fraction of an optical period. Two different methods relying on the production of coherent spontaneous emission will be described. In the first method we show that when a train of ultra-short optical pulses as short as one half period. We present calculations which show that the small signal gain is unimportant in the early stages of radiation build up in the cavity when the startup ...

Science.gov (United States)

A new dual focal point electro-optic lens that is switchable to focusing and unfocusing is proposed and successfully demonstrated. This electro-optic lens is constructed by coating transparent fine electrodes in the Fresnel-zone plate onto a PLZT ceramic plate. Its focal length changes from 1.25 m to infinity binary at 515 nm with the external voltage of 210 V. PMID:20725208

British Library Electronic Table of Contents (United Kingdom)

In this paper, we report an optical fiber sensor for measuring temperature based on bimetallic concept. The sensor is designed by following the basic principle of Fabry-Perot interferometer and theoretical detail of the sensor has been outlined here with a numerical study. An important feature of the proposed sensor is that the fabrication will be done on a commercial multimode optical fiber. The Micro-Electro-Mechanical Systems (MEMS) based fabrication process could be performed directly on a multimode optical fiber end face which will eliminate the need for adhesive in packaging. The sensor could be fabricated as sensor arrays for micro level applications. The potential application of the proposed optical sensor includes biomedical applications, nano research, microfluidics, and other ME...

International Nuclear Information System (INIS)

A previous analysis aimed at underlining the importance of the relativistic electron beam quality for the performances of a Free Electron Laser (FEL) is continued in the paper by the study of the influence of the undulator field (wiggler) parameters and of the optical beam (and/or optical cavity) quality on the operation of a FEL. The importance of parameters such as K, #lambda#_u, g of the undulator, F, P_L, #nu#_c of the optical beam, and L, L_o_p_t and L_c_r of the optical cavity for the characteristics of the input radiation as P_o_u_t, G_o_p_t, and #eta# are analyzed and some relations between these parameters that will give the possibility to estimate the corresponding values are given. Some proposal for the design of a compact FEL in IR-spectral region, with #lambda# #approx# 230 #mu#m are given. (Author).

Energy Technology Data Exchange (ETDEWEB)

An International Workshop on Metrology for X-ray and Neutron Optics has been held March 16-17, 2000, at the Advanced Photon Source, Argonne National Laboratory, near Chicago, Illinois (USA). The workshop gathered engineers and scientists from both the U.S. and around the world to evaluate metrology instrumentation and methods used to characterize surface figure and finish for long grazing incidence optics used in beamlines at synchrotrons radiation sources. This two-day workshop was motivated by the rapid evolution in the performance of x-ray and neutron sources along with requirements in optics figure and finish. More specifically, the performance of future light sources, such as free-electron laser (FEL)-based x-ray sources, is being pushed to new limits in term of both brilliance and coherence. As a consequence, tolerances on surface figure and finish of the next generation of optics are expected to ...

Science.gov (United States)

Cancer is a severe threat to human health. Early detection is considered the best way to increase the chance for survival. While the traditional cancer detection method, biopsy, is invasive, noninvasive optical diagnostic techniques are revolutionizing the way that cancer is diagnosed. Reflectance spectroscopy is one of these optical spectroscopy techniques showing promise as a diagnostic tool for pre-cancer detection. When a neoplasia occurs in tissue, morphologic and biochemical changes happen in the tissue, which in turn results in the change of optical properties and reflectance spectroscopy. Therefore, a pre-cancer can be detected by extracting optical properties from reflectance spectroscopy. This dissertation described the construction of a fiberoptic based reflectance system and the development of a series of modeling studies. This research is aimed at establishing an improved understanding of ...

International Nuclear Information System (INIS)

Superparamagnetic MFe23+O4 (M=Mn2+, Fe2+ and Co2+) 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, r2/r1, for MnFe2O4, Fe3O4 and CoFe2O4 were measured to be 12.2, 23.1 and 62.3, respectively, which demonstrate the potential usefulness of these magnetic nanoparticles as T2 contrast agents for MRI.

Energy Technology Data Exchange (ETDEWEB)

Stearic acid gel is employed to study the phase evolution of MgTiO{sub 3} nanoparticles by thermal gravimetric analysis, X-ray diffraction, and Fourier transform infrared. During the preparation of stearic acid gel, tetrabutyl titanate easily absorbed moisture to hydrolyze into Ti(OH){sub 4} firstly, and then reacts with stearic acid and magnesium stearate to form magnesium-titanium oxide network polymer gel, meanwhile n-butanol is generated. When stearic acid gel is calcined in air, a series of oxidation and combustion reactions occur, meanwhile apparent heat is given off. The results show that a metastable intermediate phase Mg{sub 2}TiO{sub 4} is generated at 450 {sup o}C and nearly disappeared at 550 {sup o}C. Simultaneously, a new solid phase of MgTiO{sub 3} appears. The metastable intermediate phase Mg{sub 2}TiO{sub 4} is successfully identified in the current work.

Energy Technology Data Exchange (ETDEWEB)

Thin, lightweight, and flexible gas-diffusion electrodes (GDEs) based on freestanding entangled networks of single-walled carbon nanotubes (SWNTs) decorated with Ag nanoparticles (AgNPs) are tested as the air-breathing cathode in a zinc-air battery. The SWNT networks provide a highly porous surface for active oxygen absorption and diffusion. The high conductivity of SWNTs coupled with the catalytic activity of AgNPs for oxygen reduction leads to an improvement in the performance of the zinc-air cell. By modulating the pH value and the reaction time, different sizes of AgNPs are decorated uniformly on the SWNTs, as revealed by transmission electron microscopy and powder X-ray diffraction. AgNPs with sizes of 3-5 nm double the capacity and specific energy of a zinc-air battery as compared with bare SWNTs. The simplified, lightweight architecture shows significant advantages over conventional carbon-based GDEs in terms of weight, thickness and conductivity, and hence ...

International Nuclear Information System (INIS)

The synthesis of narrowly dispersed nanocrystalline TiO_2 was investigated with a surfactant aided solvothermal synthetic method in toluene solutions. When a sufficient amount of titanium isopropoxide, Ti[OCH(CH_3)_2]_4 (TIP), was added to the solution, the shapes of TiO_2 nanoparticles changed from spheres to rods. The aggregated microstructures of the nano-sized TiO_2 in systems of spheres, rods, and mixtures of spheres and rods was studied using TEM. The morphological shape of the aggregation was described in terms of the fractal dimensions. We used a box-counting method to get the fractal dimension of these systems. The fitted fractal dimensions for spheres, sphere/rod mixtures, and rods are D = 1.54, D = 1.81, and D = 1.89, respectively. The fractal dimension changed from 1.54 to 1.9 with the TIP/toluene ratio, indicating that the growth mechanism for aggregations showed different behaviors.

International Nuclear Information System (INIS)

The concept of nanocrystal conversion chemistry, which involves the use of pre-formed nanoparticles as templates for chemical transformation into derivative solids, has emerged as a powerful approach for designing the synthesis of complex nanocrystalline solids. The general strategy exploits established synthetic capabilities in simple nanocrystal systems and uses these nanocrystals as templates that help to define the composition, crystal structure, and morphology of product nanocrystals. This article highlights key examples of 'conversion chemistry' approaches to the synthesis of nanocrystalline solids using a variety of techniques, including galvanic replacement, diffusion, oxidation, and ion exchange. The discussion is organized according to classes of solids, highlighting the diverse target systems that are accessible using similar chemical concepts: metals, oxides, chalcogenides, phosphides, alloys, intermetallic compounds, sulfides, and nitrides. - Graphical ...

Science.gov (United States)

Macromolecular and polyanionic Na(+)-poly(gamma-glutamic acid) (PGA) silver nitrate complex acted as both a metal ion provider and a particle protector to fabricate nanosized silver colloids under chemical reduction by dextrose. The formation and size of particles have been characterized from transmission electron microscopy (TEM), dynamic light scattering analysis and UV-vis spectrophotometer. The results showed that the average particle size was 17.2+/-3.4 to 37.3+/-5.5 nm, apparently depending on the complex concentration. It was found that the rate constant and conversion of silver nanoparticles were proportional to the concentration of PGA. The growth mechanism of nanosized silver colloid was fully discussed. In addition, the in vitro cytotoxicity evaluated by L929 fibroblasts proliferation and antibacterial activity against Gram-positive strain (methicillin-resistant S. aureus (MRSA)) and Gram-negative strain (P. aeruginosa) bacteria have been assessed. ...

Energy Technology Data Exchange (ETDEWEB)

A novel composite film, comprising of hydrophobic ionic liquid (IL), multi-walled carbon nanotubes (MWNTs) and gold nanoparticles (GNP), was fabricated and characterized. The GNP was introduced through electrochemical deposition on IL-MWNT gel film coated glassy carbon electrodes (GCE). Experiments showed that both IL and MWNTs could facilitate the GNP deposition. With GNP the composite film exhibited smaller electron transfer resistance and higher sensitivity in sensing guanine (G) and adenine (A). Under the optimized experimental conditions, the anodic peak currents were linear to the analyte concentration in the ranges of 0.008-2.0 {mu}M. The detection limits were down to nanomole level after an accumulation of 150 s on open-circuit. In addition, on the composite film coated GCE, the anodic peaks of G and A were well separated, and their response sensitivities kept almost unchanged no matter whether they coexisted or not. This proposed procedure was successfully ...

Science.gov (United States)

The interaction of the globular protein lysozyme with silica nanoparticles of diameter 20 nm was studied in a pH range between the isoelectric points (IEPs) of silica and the protein (pH 3-11). The adsorption affinity and capacity of lysozyme on the silica particles is increasing progressively with pH, and the adsorbed protein induces bridging aggregation of the silica particles. Structural properties of the aggregates were studied as a function of pH at a fixed protein-to-silica concentration ratio which corresponds to a surface concentration of protein well below a complete monolayer in the complete-binding regime at pH > 6. Sedimentation studies indicate the presence of compact aggregates at pH 4-6 and a loose flocculated network at pH 7-9, followed by a sharp decrease of aggregate size near the IEP of lysozyme. The structure of the bridged silica aggregates was studied by cryo-transmission electron microscopy (cryo-TEM) and small-angle X-ray scattering. The ...

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...

International Nuclear Information System (INIS)

In laser ablation inductively coupled plasma mass spectrometry (LA-ICPMS), the properties of laser-generated aerosols, such as size and composition, are crucial for matrix-independent quantification. In this study, the aerosol particle morphology and elemental composition generated by two state-of-the-art laser systems (ArF excimer nanosecond-UV laser and Ti:sapphire femtosecond-IR laser) were investigated by electron microscopic techniques. Electrostatic sampling of the aerosols directly onto transmission electron microscopy (TEM) grids allowed us to study the morphology and elemental composition of the aerosols using TEM and TEM-EDX (energy dispersive X-ray spectroscopy) analyses, respectively. The results of the electron microscopic studies were finally compared to the LA-ICPMS signals of the main matrix components. The investigations were carried out for non-conducting materials (glass and zircon), metallic samples (steel and brass) and semiconductors (sulfides). The studies ...

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.

Energy Technology Data Exchange (ETDEWEB)

Instrumentation research to study the feasibility of using optical data processing techniques to solve real-time pattern recognition problems for high energy physics experiments is now in its second year. During the past year, a prototype optical processor for use in BNL Experiment 702 was conceived and designed, using test data from the experiment and simulating the optical processor in the computer. A number of technical studies have been made, mostly relating to the selection of the optical filter for the processor. Comparisons between natural and synthetic holograms, both bleached and unbleached, have been made. We conclude from these tests that the kinoform, a computer-generated phase hologram, is the optimal choice for this processor. A new method for producing the kinoform has been tried by this group with encouraging results. The optical design for the prototype processor is ...

Science.gov (United States)

In this article we describe an optoelectronic sensor for assessing the level of light petrochemical products in technological tanks at the oil refineries. This sensor employs the multi-element vertical array of discrete micro- optical refractometric transducers. The transducers are made of silica glass and have the conical shape. In the air, each transducer operates as a tiny retro-reflector that optically couple together two multimode optical fibers. The optical coupling in the transducer is due to the internal reflection at the conical surface. The amount of the coupling depends on the refractive index of the surrounding media. In a fluid, the total internal reflection vanishes and the coupling becomes negligibly small. The number of immersed transducers is a measure of the fluid level in the reservoir. Because of the significance of the transducer transmission function, it is evaluated in detail ...

Science.gov (United States)

The PLANCK SURVEYOR is a European Space Agency satellite mission to image the very faint anisotropies in the temperature of the Cosmic Microwave Background (CMB) radiation. Maynooth is actively participating in an international collaboration of scientists involved with the optical design of the High Frequency Instrument (HFI). This paper outlines research which has been undertaken in Maynooth concerned with numerical modelling of the optical characteristics of the multi-frequency array of detectors making up the HFI instrument. In the study the commercial software package ZEMAX was used to model the coupling of the focal plane HFI detectors to the PLANCK telescope. This package is particularly useful in the optical design of PLANCK because of the powerful optimisation features of the software. It is thus possible to readily determine the optimum positioning of the detectors in the focal plane of the telescope. Although the ...

Science.gov (United States)

The optically stimulated luminescent (OSL) radiation dosimeter technically surveys a wide dynamic measurement range and a high sensitivity. Optical fiber dosimeters provide capability for remote monitoring of the radiation in the locations which are difficult-to-access and hazardous. In addition, optical fiber dosimeters are immune to electrical and radio-frequency interference. In this paper, a novel remote optical fiber radiation dosimeter is described. The optical fiber dosimeter takes advantage of the charge trapping materials CaS:Ce, Sm that exhibit OSL. The measuring range of the dosimeter is from 0.1 to 100 Gy. The equipment is relatively simple and small in size, and has low power consumption. This device is suitable for measuring the space radiation dose and also can be used in high radiation dose condition and other dangerous radiation occasions. Supported by National ...

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 quenching of photoluminescence of the small ...

International Nuclear Information System (INIS)

The optical pressure exerted o a thin film, which is locked in the evanescent field formed at the plane interface with a totally-reflected Gaussian beam, is investigated. Some calculations of the pressure on the film caused by the evanescent field are presented in the different conditions of film thickness, film position, incident angle and polarization of a gaussian beam. The results show that the pressure exertion on the thin film can change from pushing to pulling as the parameters are varied. In particular, we find that the direction of optical pressure can act oppositely at the different positions of the film surface in the evanescent field.

CERN Document Server

Individual laser cooled atoms are delivered on demand from a single atom magneto-optic trap to a high-finesse optical cavity using an atom conveyor. Strong coupling of the atom with the cavity field allows simultaneous cooling and detection of individual atoms for time scales exceeding 15 s. The single atom scatter rate is studied as a function of probe-cavity detuning and probe Rabi frequency, and the experimental results are in good agreement with theoretical predictions. We demonstrate the ability to manipulate the position of a single atom relative to the cavity mode with excellent control and reproducibility.

UK PubMed Central (United Kingdom)

BackgroundVisual acuity, the ability of the visual system to distinguish two separate objects at a given angular distance, is influenced by the optical and neuronal properties of...Full Text Available

Science.gov (United States)

... 13 2.4 Inertial Navigation Error Model . . . . . ... sources such as electrical noise, thermal noise, etc. 2.4 Inertial Navigation Error Model ...

KoreaScience (Korea)

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International Nuclear Information System (INIS)

The structural, electronic and optical properties of ZnX and CdX (X = Se, Te and S) are studied using density functional theory by the Wien2k package. The energy band gap, real and imaginary parts of the dielectric function, energy loss function, optical absorption coefficient and reflectivity spectra of these compounds are calculated. The Engel-Vosko approach improves the energy band gaps of ZnX and CdX compounds. The calculated optical parameters are in good agreement with available experimental results, particularly in the Engel-Vosko approach. Furthermore the effect of hydrostatic pressure on the energy band gap, the real and imaginary parts of the dielectric function of these compounds is studied. The first and second order pressure coefficient for the energy band gaps, the static dielectric function and the static reflectivity spectra are calculated.