A Brief Introduction to Single-Molecule Fluorescence Methods.

Science.gov (United States)

van den Wildenberg, Siet M J L; Prevo, Bram; Peterman, Erwin J G

2018-01-01

One of the more popular single-molecule approaches in biological science is single-molecule fluorescence microscopy, which will be the subject of the following section of this volume. Fluorescence methods provide the sensitivity required to study biology on the single-molecule level, but they also allow access to useful measurable parameters on time and length scales relevant for the biomolecular world. Before several detailed experimental approaches will be addressed, we will first give a general overview of single-molecule fluorescence microscopy. We start with discussing the phenomenon of fluorescence in general and the history of single-molecule fluorescence microscopy. Next, we will review fluorescent probes in more detail and the equipment required to visualize them on the single-molecule level. We will end with a description of parameters measurable with such approaches, ranging from protein counting and tracking, single-molecule localization super-resolution microscopy, to distance measurements with Förster Resonance Energy Transfer and orientation measurements with fluorescence polarization.

Total Internal Reflection Fluorescence Microscopy Imaging-Guided Confocal Single-Molecule Fluorescence Spectroscopy

OpenAIRE

Zheng, Desheng; Kaldaras, Leonora; Lu, H. Peter

2013-01-01

We have developed an integrated spectroscopy system combining total internal reflection fluorescence microscopy imaging with confocal single-molecule fluorescence spectroscopy for two-dimensional interfaces. This spectroscopy approach is capable of both multiple molecules simultaneously sampling and in situ confocal fluorescence dynamics analyses of individual molecules of interest. We have demonstrated the calibration with fluorescent microspheres, and carried out single-molecule spectroscop...

Fluorescent Biosensors Based on Single-Molecule Counting.

Science.gov (United States)

Ma, Fei; Li, Ying; Tang, Bo; Zhang, Chun-Yang

2016-09-20

Biosensors for highly sensitive, selective, and rapid quantification of specific biomolecules make great contributions to biomedical research, especially molecular diagnostics. However, conventional methods for biomolecular assays often suffer from insufficient sensitivity and poor specificity. In some case (e.g., early disease diagnostics), the concentration of target biomolecules is too low to be detected by these routine approaches, and cumbersome procedures are needed to improve the detection sensitivity. Therefore, there is an urgent need for rapid and ultrasensitive analytical tools. In this respect, single-molecule fluorescence approaches may well satisfy the requirement and hold promising potential for the development of ultrasensitive biosensors. Encouragingly, owing to the advances in single-molecule microscopy and spectroscopy over past decades, the detection of single fluorescent molecule comes true, greatly boosting the development of highly sensitive biosensors. By in vitro/in vivo labeling of target biomolecules with proper fluorescent tags, the quantification of certain biomolecule at the single-molecule level is achieved. In comparison with conventional ensemble measurements, single-molecule detection-based analytical methods possess the advantages of ultrahigh sensitivity, good selectivity, rapid analysis time, and low sample consumption. Consequently, single-molecule detection may be potentially employed as an ideal analytical approach to quantify low-abundant biomolecules with rapidity and simplicity. In this Account, we will summarize our efforts for developing a series of ultrasensitive biosensors based on single-molecule counting. Single-molecule counting is a member of single-molecule detection technologies and may be used as a very simple and ultrasensitive method to quantify target molecules by simply counting the individual fluorescent bursts. In the fluorescent sensors, the signals of target biomolecules may be translated to the

Integrated Transmission Electron and Single-Molecule Fluorescence Microscopy Correlates Reactivity with Ultrastructure in a Single Catalyst Particle

OpenAIRE

Hendriks, Frank C.; Mohammadian, Sajjad; Ristanovic, Zoran; Kalirai, Samanbir; Meirer, Florian; Vogt, Eelco T. C.; Bruijnincx, Pieter C. A.; Gerritsen, Hans; Weckhuysen, Bert M.

2018-01-01

Establishing structure–activity relationships in complex, hierarchically structured nanomaterials, such as fluid catalytic cracking (FCC) catalysts, requires characterization with complementary, correlated analysis techniques. An integrated setup has been developed to perform transmission electron microscopy (TEM) and single-molecule fluorescence (SMF) microscopy on such nanostructured samples. Correlated structure–reactivity information was obtained for 100 nm thin, microtomed sections of a ...

Structural and fluorescence properties of Ni:MgO-SiO2 particles synthesized by flame spray pyrolysis

International Nuclear Information System (INIS)

Suzuki, Takenobu; Ohishi, Yasutake; Tani, Takao

2006-01-01

Structural and fluorescence properties of flame spray-synthesized Ni 1 mol%-doped MgO-SiO 2 nano-particles (MgO:SiO 2 = 100:0, 50:50, 25:75 and 0:100 in mol%) were investigated as a first step to prepare transparent materials containing Ni:MgO for optical gain media. Polyhedral aggregates of primary particles with diameters of 8-19 nm were obtained for all compositions. The 100MgO particles were single crystalline and showed the fluorescences (centered at 1260 and 1320 nm) and lifetime (3.8 ms) similar to those of solid state-synthesized Ni:MgO polycrystalline powder under laser excitation at 976 nm, suggesting Ni ions incorporated in MgO

Fluorescence labelling as tool for zeolite particle tracking in nanoremediation approaches

International Nuclear Information System (INIS)

Gillies, Glenn; Mackenzie, Katrin; Kopinke, Frank-Dieter; Georgi, Anett

2016-01-01

Colloidal Fe-zeolites such as Fe-BEA-35 are currently under study as new adsorbent and catalyst materials for in-situ chemical oxidation with H_2O_2. As for nanoremediation in general, the availability of suitable particle detection methods is a requirement for successful process development and particle tracing. Detection and distinguishing between natural colloids and introduced particles with a similar composition are a challenge. By means of fluorescence labelling, a highly specific detection option for Fe-BEA-35 was developed. ‘Ship-in-a-bottle’ synthesis of fluorescein within the zeolite pores, which was applied for the first time for a BEA type zeolite, provides a product with stable and non-extractable fluorescence. When the fluorescent labelled zeolite is added at a concentration of 1 wt.% referring to the total zeolite mass, a very low detection limit of 1 mg/L of total zeolite is obtained. Compared to commonly applied turbidity measurements, detection via fluorescence labelling is much more specific and sensitive. Fluorescence is only marginally affected by carboxymethyl cellulose, which is frequently applied as stabilizer in application suspensions but will be depleted upon contact with H_2O_2. Transport properties of fluorescent labelled and non-labelled Fe-zeolite particles are in agreement as determined in a column study with quartz sand and synthetic groundwater (classified as very hard). - Highlights: • Fluorescent BEA zeolite was prepared for first time by ‘ship-in-a-bottle’ synthesis. • Fluorescein synthesized inside zeolite channels is stable and non-extractable. • Detection limit of Fe-zeolite particles in suspension with 1 wt.% fluorescent zeolite is 1 mg/L. • Transport properties of fluorescent and Fe-loaded BEA particles are identical.

Raman and fluorescent scattering by molecules embedded in small particles

International Nuclear Information System (INIS)

Chew, H.W.; McNulty, P.J.

1983-01-01

We have formulated a model for fluorescent and Raman scattering by molecules embedded in or in the vicinity of small particles. The model takes into account the size, shape, refractive index, and morphology of the host particles. Analytic and numerical results have been obtained for spherical (one and more layers, including magnetic dipole transitions) cylindrical and spheroidal particles. Particular attention has been given to the spherical case with fluorescent/Raman scatterers uniformly distributed in the particles radiating both coherently and incohorently. Depolarization effects have been studied with suitable averaging process, and good agreement with experiment has been obtained. Analytic and numerical results have been obtained for the elastic scattering of evanescent waves; these results are useful for the study of fluorescent under excitation by evanescent waves

A brief introduction to single-molecule fluorescence methods

NARCIS (Netherlands)

Wildenberg, S.M.J.L.; Prevo, B.; Peterman, E.J.G.; Peterman, EJG; Wuite, GJL

2011-01-01

One of the more popular single-molecule approaches in biological science is single-molecule fluorescence microscopy, which is the subject of the following section of this volume. Fluorescence methods provide the sensitivity required to study biology on the single-molecule level, but they also allow

A brief introduction to single-molecule fluorescence methods

NARCIS (Netherlands)

van den Wildenberg, Siet M.J.L.; Prevo, Bram; Peterman, Erwin J.G.

2018-01-01

One of the more popular single-molecule approaches in biological science is single-molecule fluorescence microscopy, which will be the subject of the following section of this volume. Fluorescence methods provide the sensitivity required to study biology on the single-molecule level, but they also

Highly sensitive immunoassay of protein molecules based on single nanoparticle fluorescence detection in a nanowell

Science.gov (United States)

Han, Jin-Hee; Kim, Hee-Joo; Lakshmana, Sudheendra; Gee, Shirley J.; Hammock, Bruce D.; Kennedy, Ian M.

2011-03-01

A nanoarray based-single molecule detection system was developed for detecting proteins with extremely high sensitivity. The nanoarray was able to effectively trap nanoparticles conjugated with biological sample into nanowells by integrating with an electrophoretic particle entrapment system (EPES). The nanoarray/EPES is superior to other biosensor using immunoassays in terms of saving the amounts of biological solution and enhancing kinetics of antibody binding due to reduced steric hindrance from the neighboring biological molecules. The nanoarray patterned onto a layer of PMMA and LOL on conductive and transparent indium tin oxide (ITO)-glass slide by using e-beam lithography. The suspension of 500 nm-fluorescent (green emission)-carboxylated polystyrene (PS) particles coated with protein-A followed by BDE 47 polyclonal antibody was added to the chip that was connected to the positive voltage. The droplet was covered by another ITO-coated-glass slide and connected to a ground terminal. After trapping the particles into the nanowells, the solution of different concentrations of anti-rabbit- IgG labeled with Alexa 532 was added for an immunoassay. A single molecule detection system could quantify the anti-rabbit IgG down to atto-mole level by counting photons emitted from the fluorescent dye bound to a single nanoparticle in a nanowell.

Visible to near-IR fluorescence from single-digit detonation nanodiamonds: excitation wavelength and pH dependence.

Science.gov (United States)

Reineck, Philipp; Lau, Desmond W M; Wilson, Emma R; Nunn, Nicholas; Shenderova, Olga A; Gibson, Brant C

2018-02-06

Detonation nanodiamonds are of vital significance to many areas of science and technology. However, their fluorescence properties have rarely been explored for applications and remain poorly understood. We demonstrate significant fluorescence from the visible to near-infrared spectral regions from deaggregated, single-digit detonation nanodiamonds dispersed in water produced via post-synthesis oxidation. The excitation wavelength dependence of this fluorescence is analyzed in the spectral region from 400 nm to 700 nm as well as the particles' absorption characteristics. We report a strong pH dependence of the fluorescence and compare our results to the pH dependent fluorescence of aromatic hydrocarbons. Our results significantly contribute to the current understanding of the fluorescence of carbon-based nanomaterials in general and detonation nanodiamonds in particular.

Quantitative cellular uptake of double fluorescent core-shelled model submicronic particles

Energy Technology Data Exchange (ETDEWEB)

Leclerc, Lara, E-mail: leclerc@emse.fr [Ecole Nationale Superieure des Mines, CIS-EMSE, LINA (France); Boudard, Delphine [LINA (France); Pourchez, Jeremie; Forest, Valerie [Ecole Nationale Superieure des Mines, CIS-EMSE, LINA (France); Marmuse, Laurence; Louis, Cedric [NANO-H S.A.S (France); Bin, Valerie [LINA (France); Palle, Sabine [Universite Jean Monnet, Centre de Microscopie Confocale Multiphotonique (France); Grosseau, Philippe; Bernache-Assollant, Didier [Ecole Nationale Superieure des Mines, CIS-EMSE, LINA (France); Cottier, Michele [LINA (France)

2012-11-15

The relationship between particles' physicochemical parameters, their uptake by cells and their degree of biological toxicity represent a crucial issue, especially for the development of new technologies such as fabrication of micro- and nanoparticles in the promising field of drug delivery systems. This work was aimed at developing a proof-of-concept for a novel model of double fluorescence submicronic particles that could be spotted inside phagolysosomes. Fluorescein isothiocyanate (FITC) particles were synthesized and then conjugated with a fluorescent pHrodo Trade-Mark-Sign probe, red fluorescence of which increases in acidic conditions such as within lysosomes. After validation in acellular conditions by spectral analysis with confocal microscopy and dynamic light scattering, quantification of phagocytosis was conducted on a macrophage cell line in vitro. The biological impact of pHrodo functionalization (cytotoxicity, inflammatory response, and oxidative stress) was also investigated. Results validate the proof-of-concept of double fluorescent particles (FITC + pHrodo), allowing detection of entirely engulfed pHrodo particles (green and red labeling). Moreover incorporation of pHrodo had no major effects on cytotoxicity compared to particles without pHrodo, making them a powerful tool for micro- and nanotechnologies.

A comparison of single particle tracking and temporal image correlation spectroscopy for quantitative analysis of endosome motility

DEFF Research Database (Denmark)

Lund, F. W.; Wustner, D.

2013-01-01

Single particle tracking (SPT) is becoming a standard method to extract transport parameters from time-lapse image sequences of fluorescent vesicles in living cells. Another method to obtain these data is temporal image correlation spectroscopy (TICS), but this method is less often used for measu......Single particle tracking (SPT) is becoming a standard method to extract transport parameters from time-lapse image sequences of fluorescent vesicles in living cells. Another method to obtain these data is temporal image correlation spectroscopy (TICS), but this method is less often used...... for measurement of intracellular vesicle transport. Here, we present an extensive comparison of SPT and TICS. First we examine the effect of photobleaching, shading and noise on SPT and TICS analysis using simulated image sequences. To this end, we developed a simple photophysical model, which relates spatially...... varying illumination intensity to the bleaching propensity and fluorescence intensity of the moving particles. We found that neither SPT nor TICS are affected by photobleaching per se, but the transport parameters obtained by both methods are sensitive to the signal-to-noise ratio. In addition, the number...

Fluorescence single-molecule counting assays for protein quantification using epi-fluorescence microscopy with quantum dots labeling

International Nuclear Information System (INIS)

Jiang Dafeng; Liu Chunxia; Wang Lei; Jiang Wei

2010-01-01

A single-molecule counting approach for quantifying the antibody affixed to a surface using quantum dots and epi-fluorescence microscopy is presented. Modifying the glass substrates with carboxyl groups provides a hydrophilic surface that reacts with amine groups of an antibody to allow covalent immobilization of the antibody. Nonspecific adsorption of single molecules on the modified surfaces was first investigated. Then, quantum dots were employed to form complexes with surface-immobilized antibody molecules and used as fluorescent probes for single-molecule imaging. Epi-fluorescence microscopy was chosen as the tool for single-molecule fluorescence detection here. The generated fluorescence signals were taken by an electron multiplying charge-coupled device and were found to be proportional to the sample concentrations. Under optimal conditions, a linear response range of 5.0 x 10 -14 -3.0 x 10 -12 mol L -1 was obtained between the number of single molecules and sample concentration via a single-molecule counting approach.

BIOCOMPATIBLE FLUORESCENT MICROSPHERES: SAFE PARTICLES FOR MATERIAL PENETRATION STUDIES

Energy Technology Data Exchange (ETDEWEB)

farquar, G; Leif, R

2008-09-12

Biocompatible polymers with hydrolyzable chemical bonds are being used to produce safe, non-toxic fluorescent microspheres for material penetration studies. The selection of polymeric materials depends on both biocompatibility and processability, with tailored fluorescent properties depending on specific applications. Microspheres are composed of USFDA-approved biodegradable polymers and non-toxic fluorophores and are therefore suitable for tests where human exposure is possible. Micropheres are being produced which contain unique fluorophores to enable discrimination from background aerosol particles. Characteristics that affect dispersion and adhesion can be modified depending on use. Several different microsphere preparation methods are possible, including the use of a vibrating orifice aerosol generator (VOAG), a Sono-Tek atomizer, an emulsion technique, and inkjet printhead. The advantages and disadvantages of each method will be presented and discussed in greater detail along with fluorescent and charge properties of the aerosols. Applications for the fluorescent microspheres include challenges for biodefense system testing, calibrants for biofluorescence sensors, and particles for air dispersion model validation studies.

Single particle detecting telescope system

International Nuclear Information System (INIS)

Yamamoto, I.; Tomiyama, T.; Iga, Y.; Komatsubara, T.; Kanada, M.; Yamashita, Y.; Wada, T.; Furukawa, S.

1981-01-01

We constructed the single particle detecting telescope system for detecting a fractionally charged particle. The telescope consists of position detecting counters, wall-less multi-cell chambers, single detecting circuits and microcomputer system as data I/0 processor. Especially, a frequency of double particle is compared the case of the single particle detecting with the case of an ordinary measurement

BIOCOMPATIBLE FLUORESCENT MICROSPHERES: SAFE PARTICLES FOR MATERIAL PENETRATION STUDIES

Energy Technology Data Exchange (ETDEWEB)

Farquar, G; Leif, R

2009-07-15

Biocompatible polymers with hydrolyzable chemical bonds have been used to produce safe, non-toxic fluorescent microspheres for material penetration studies. The selection of polymeric materials depends on both biocompatibility and processability, with tailored fluorescent properties depending on specific applications. Microspheres are composed of USFDA-approved biodegradable polymers and non-toxic fluorophores and are therefore suitable for tests where human exposure is possible. Micropheres were produced which contain unique fluorophores to enable discrimination from background aerosol particles. Characteristics that affect dispersion and adhesion can be modified depending on use. Several different microsphere preparation methods are possible, including the use of a vibrating orifice aerosol generator (VOAG), a Sono-Tek atomizer, an emulsion technique, and inkjet printhead. Applications for the fluorescent microspheres include challenges for biodefense system testing, calibrants for biofluorescence sensors, and particles for air dispersion model validation studies.

Distributed Sensor Particles for Remote Fluorescence Detection of Trace Analytes: UXO/CW; TOPICAL

International Nuclear Information System (INIS)

SINGH, ANUP K.; GUPTA, ALOK; MULCHANDANI, ASHOK; CHEN, WILFRED; BHATIA, RIMPLE B.; SCHOENIGER, JOSEPH S.; ASHLEY, CAROL S.; BRINKER, C. JEFFREY; HANCE, BRADLEY G.; SCHMITT, RANDAL L.; JOHNSON, MARK S.; HARGIS JR. PHILIP J.; SIMONSON, ROBERT J.

2001-01-01

This report summarizes the development of sensor particles for remote detection of trace chemical analytes over broad areas, e.g residual trinitrotoluene from buried landmines or other unexploded ordnance (UXO). We also describe the potential of the sensor particle approach for the detection of chemical warfare (CW) agents. The primary goal of this work has been the development of sensor particles that incorporate sample preconcentration, analyte molecular recognition, chemical signal amplification, and fluorescence signal transduction within a ''grain of sand''. Two approaches for particle-based chemical-to-fluorescence signal transduction are described: (1) enzyme-amplified immunoassays using biocompatible inorganic encapsulants, and (2) oxidative quenching of a unique fluorescent polymer by TNT

Conditional-sampling spectrograph detection system for fluorescence measurements of individual airborne biological particles

Science.gov (United States)

Nachman, Paul; Pinnick, R. G.; Hill, Steven C.; Chen, Gang; Chang, Richard K.; Mayo, Michael W.; Fernandez, Gilbert L.

1996-03-01

We report the design and operation of a prototype conditional-sampling spectrograph detection system that can record the fluorescence spectra of individual, micrometer-sized aerosols as they traverse an intense 488-nm intracavity laser beam. The instrument's image-intensified CCD detector is gated by elastic scattering or by undispersed fluorescence from particles that enter the spectrograph's field of view. It records spectra only from particles with preselected scattering-fluorescence levels (a fiber-optic-photomultiplier subsystem provides the gating signal). This conditional-sampling procedure reduces data-handling rates and increases the signal-to-noise ratio by restricting the system's exposures to brief periods when aerosols traverse the beam. We demonstrate these advantages by reliably capturing spectra from individual fluorescent microspheres dispersed in an airstream. The conditional-sampling procedure also permits some discrimination among different types of particles, so that spectra may be recorded from the few interesting particles present in a cloud of background aerosol. We demonstrate such discrimination by measuring spectra from selected fluorescent microspheres in a mixture of two types of microspheres, and from bacterial spores in a mixture of spores and nonfluorescent kaolin particles.

Single particle dynamics

International Nuclear Information System (INIS)

Siemens, P.J.; Jensen, A.S.

1985-01-01

It is shown that the opening of the 3-quasiparticle continuum at 3Δ sets the energy scale for the enhancement of the effective mass near the Fermi surface of nuclei. The authors argue that the spreading width of single-particle states due to coupling with low-lying collective modes is qualitatively different from the two-body collision mechanism, and contributes little to the single-particle lifetime in the sense of the optical model. (orig.)

Submicron polymer particles containing fluorescent semiconductor nanocrystals CdSe/ZnS for bioassays.

Science.gov (United States)

Generalova, Alla N; Sizova, Svetlana V; Zdobnova, Tatiana A; Zarifullina, Margarita M; Artemyev, Michail V; Baranov, Alexander V; Oleinikov, Vladimir A; Zubov, Vitaly P; Deyev, Sergey M

2011-02-01

This study aimed to design a panel of uniform particulate biochemical reagents and to test them in specific bioassays. These reagents are polymer particles of different sizes doped with semiconductor nanocrystals and conjugated with either full-size antibodies or recombinant mini-antibodies (4D5 scFv fragment) designed by genetic engineering approaches. A panel of highly fluorescent polymer particles (150-800 nm) were formed by embedding CdSe/ZnS nanocrystals (quantum dots) into preformed polyacrolein and poly(acrolein-co-styrene) particles. Morphology, content and fluorescence characteristics of the prepared materials were studied by laser correlation spectroscopy, spectrophotometry, optical and fluorescent microscopy and fluorimetry. The obtained fluorescent particles sensitized by anti-Yersinia pestis antibodies were used for rapid agglutination glass test suitable for screening analysis of Y. pestis antigen and for microtiter particle agglutination, which, owing to its speed and simplicity, is very beneficial for diagnostic detection of Y. pestis antigen. Recombinant 4D5 scFv antibodies designed and conjugated with polymer particles containing quantum dots provide multipoint highly specific binding with cancer marker HER2/neu on the surface of SKOV-3 cell.

Dual-modality single particle orientation and rotational tracking of intracellular transport of nanocargos.

Science.gov (United States)

Sun, Wei; Gu, Yan; Wang, Gufeng; Fang, Ning

2012-01-17

The single particle orientation and rotational tracking (SPORT) technique was introduced recently to follow the rotational motion of plasmonic gold nanorod under a differential interference contrast (DIC) microscope. In biological studies, however, cellular activities usually involve a multiplicity of molecules; thus, tracking the motion of a single molecule/object is insufficient. Fluorescence-based techniques have long been used to follow the spatial and temporal distributions of biomolecules of interest thanks to the availability of multiplexing fluorescent probes. To know the type and number of molecules and the timing of their involvement in a biological process under investigation by SPORT, we constructed a dual-modality DIC/fluorescence microscope to simultaneously image fluorescently tagged biomolecules and plasmonic nanoprobes in living cells. With the dual-modality SPORT technique, the microtubule-based intracellular transport can be unambiguously identified while the dynamic orientation of nanometer-sized cargos can be monitored at video rate. Furthermore, the active transport on the microtubule can be easily separated from the diffusion before the nanocargo docks on the microtubule or after it undocks from the microtubule. The potential of dual-modality SPORT is demonstrated for shedding new light on unresolved questions in intracellular transport.

Time-Lapse Monitoring of DNA Damage Colocalized With Particle Tracks in Single Living Cells

Energy Technology Data Exchange (ETDEWEB)

McFadden, Conor H. [Department of Radiation Physics, The University of Texas MD Anderson Cancer Center, Houston, Texas (United States); Hallacy, Timothy M. [Department of Radiation Physics, The University of Texas MD Anderson Cancer Center, Houston, Texas (United States); Department of Physics and Astronomy, Rice University, Houston, Texas (United States); Flint, David B. [Department of Radiation Physics, The University of Texas MD Anderson Cancer Center, Houston, Texas (United States); Graduate School of Biomedical Sciences, The University of Texas, Houston, Texas (United States); Granville, Dal A. [Department of Medical Physics, The Ottawa Hospital Cancer Centre, Ottawa, Ontario (Canada); Asaithamby, Aroumougame [Division of Molecular Radiation Biology, Department of Radiation Oncology, University of Texas Southwestern Medical Centre, Dallas, Texas (United States); Sahoo, Narayan [Department of Radiation Physics, The University of Texas MD Anderson Cancer Center, Houston, Texas (United States); Akselrod, Mark S. [Crystal Growth Division, Landauer, Inc, Stillwater, Oklahoma (United States); Sawakuchi, Gabriel O., E-mail: gsawakuchi@mdanderson.org [Department of Radiation Physics, The University of Texas MD Anderson Cancer Center, Houston, Texas (United States); Graduate School of Biomedical Sciences, The University of Texas, Houston, Texas (United States)

2016-09-01

Purpose: Understanding the DNA damage and repair induced by hadron therapy (HT) beams is crucial for developing novel strategies to maximize the use of HT beams to treat cancer patients. However, spatiotemporal studies of DNA damage and repair for beam energies relevant to HT have been challenging. We report a technique that enables spatiotemporal measurement of radiation-induced damage in live cells and colocalization of this damage with charged particle tracks over a broad range of clinically relevant beam energies. The technique uses novel fluorescence nuclear track detectors with fluorescence confocal laser scanning microscopy in the beam line to visualize particle track traversals within the subcellular compartments of live cells within seconds after injury. Methods and Materials: We designed and built a portable fluorescence confocal laser scanning microscope for use in the beam path, coated fluorescence nuclear track detectors with fluorescent-tagged live cells (HT1080 expressing enhanced green fluorescent protein tagged to XRCC1, a single-strand break repair protein), placed the entire assembly into a proton therapy beam line, and irradiated the cells with a fluence of ∼1 × 10{sup 6} protons/cm{sup 2}. Results: We successfully obtained confocal images of proton tracks and foci of DNA single-strand breaks immediately after irradiation. Conclusions: This technique represents an innovative method for analyzing biological responses in any HT beam line at energies and dose rates relevant to therapy. It allows precise determination of the number of tracks traversing a subcellular compartment and monitoring the cellular damage therein, and has the potential to measure the linear energy transfer of each track from therapeutic beams.

A Starting Point for Fluorescence-Based Single-Molecule Measurements in Biomolecular Research

Directory of Open Access Journals (Sweden)

Alexander Gust

2014-09-01

Full Text Available Single-molecule fluorescence techniques are ideally suited to provide information about the structure-function-dynamics relationship of a biomolecule as static and dynamic heterogeneity can be easily detected. However, what type of single-molecule fluorescence technique is suited for which kind of biological question and what are the obstacles on the way to a successful single-molecule microscopy experiment? In this review, we provide practical insights into fluorescence-based single-molecule experiments aiming for scientists who wish to take their experiments to the single-molecule level. We especially focus on fluorescence resonance energy transfer (FRET experiments as these are a widely employed tool for the investigation of biomolecular mechanisms. We will guide the reader through the most critical steps that determine the success and quality of diffusion-based confocal and immobilization-based total internal reflection fluorescence microscopy. We discuss the specific chemical and photophysical requirements that make fluorescent dyes suitable for single-molecule fluorescence experiments. Most importantly, we review recently emerged photoprotection systems as well as passivation and immobilization strategies that enable the observation of fluorescently labeled molecules under biocompatible conditions. Moreover, we discuss how the optical single-molecule toolkit has been extended in recent years to capture the physiological complexity of a cell making it even more relevant for biological research.

Single-molecule fluorescence microscopy review: shedding new light on old problems.

Science.gov (United States)

Shashkova, Sviatlana; Leake, Mark C

2017-08-31

Fluorescence microscopy is an invaluable tool in the biosciences, a genuine workhorse technique offering exceptional contrast in conjunction with high specificity of labelling with relatively minimal perturbation to biological samples compared with many competing biophysical techniques. Improvements in detector and dye technologies coupled to advances in image analysis methods have fuelled recent development towards single-molecule fluorescence microscopy, which can utilize light microscopy tools to enable the faithful detection and analysis of single fluorescent molecules used as reporter tags in biological samples. For example, the discovery of GFP, initiating the so-called 'green revolution', has pushed experimental tools in the biosciences to a completely new level of functional imaging of living samples, culminating in single fluorescent protein molecule detection. Today, fluorescence microscopy is an indispensable tool in single-molecule investigations, providing a high signal-to-noise ratio for visualization while still retaining the key features in the physiological context of native biological systems. In this review, we discuss some of the recent discoveries in the life sciences which have been enabled using single-molecule fluorescence microscopy, paying particular attention to the so-called 'super-resolution' fluorescence microscopy techniques in live cells, which are at the cutting-edge of these methods. In particular, how these tools can reveal new insights into long-standing puzzles in biology: old problems, which have been impossible to tackle using other more traditional tools until the emergence of new single-molecule fluorescence microscopy techniques. © 2017 The Author(s).

Enhancement of single-molecule fluorescence signals by colloidal silver nanoparticles in studies of protein translation.

Science.gov (United States)

Bharill, Shashank; Chen, Chunlai; Stevens, Benjamin; Kaur, Jaskiran; Smilansky, Zeev; Mandecki, Wlodek; Gryczynski, Ignacy; Gryczynski, Zygmunt; Cooperman, Barry S; Goldman, Yale E

2011-01-25

Metal-enhanced fluorescence (MEF) increased total photon emission of Cy3- and Cy5-labeled ribosomal initiation complexes near 50 nm silver particles 4- and 5.5-fold, respectively. Fluorescence intensity fluctuations above shot noise, at 0.1-5 Hz, were greater on silver particles. Overall signal-to-noise ratio was similar or slightly improved near the particles. Proximity to silver particles did not compromise ribosome function, as measured by codon-dependent binding of fluorescent tRNA, dynamics of fluorescence resonance energy transfer between adjacent tRNAs in the ribosome, and tRNA translocation induced by elongation factor G.

Enhancement of Single Molecule Fluorescence Signals by Colloidal Silver Nanoparticles in Studies of Protein Translation

Science.gov (United States)

Bharill, Shashank; Chen, Chunlai; Stevens, Benjamin; Kaur, Jaskiran; Smilansky, Zeev; Mandecki, Wlodek; Gryczynski, Ignacy; Gryczynski, Zygmunt; Cooperman, Barry S.; Goldman, Yale E.

2011-01-01

Metal enhanced fluorescence (MEF) increased total photon emission of Cy3- and Cy5-labeled ribosomal initiation complexes near 50 nm silver particles 4- and 5.5-fold respectively. Fluorescence intensity fluctuations above shot noise, at 0.1 – 5 Hz, were greater on silver particles. Overall signal to noise ratio was similar or slightly improved near the particles. Proximity to silver particles did not compromise ribosome function, as measured by codon-dependent binding of fluorescent tRNA, dynamics of fluorescence resonance energy transfer between adjacent tRNAs in the ribosome, and tRNA translocation induced by elongation factor G. PMID:21158483

Synthesis of highly monodisperse particles composed of a magnetic core and fluorescent shell.

Science.gov (United States)

Nagao, Daisuke; Yokoyama, Mikio; Yamauchi, Noriko; Matsumoto, Hideki; Kobayashi, Yoshio; Konno, Mikio

2008-09-02

Highly monodisperse particles composed of a magnetic silica core and fluorescent polymer shell were synthesized with a combined technique of heterocoagulation and soap-free emulsion polymerization. Prior to heterocoagulation, monodisperse, submicrometer-sized silica particles were prepared with the Stober method, and magnetic nanoparticles were prepared with a modified Massart method in which a cationic silane coupling agent of N-trimethoxysilylpropyl- N, N, N-trimethylammonium chloride was added just after coprecipitation of Fe (2+) and Fe (3+). The silica particles with negative surface potential were heterocoagulated with the magnetic nanoparticles with positive surface potential. The magnetic silica particles obtained with the heterocoagulation were treated with sodium silicate to modify their surfaces with silica. In the formation of a fluorescent polymer shell onto the silica-coated magnetic silica cores, an amphoteric initiator of 2,2'-azobis[ N-(2-carboxyethyl)-2-2-methylpropionamidine] (VA-057) was used to control the colloidal stability of the magnetic cores during the polymer coating. The polymerization of St in the presence of a hydrophobic fluorophore of pyrene could coat the cores with fluorescent polymer shells, resulting in monodisperse particles with a magnetic silica core and fluorescent polymer shell. Measurements of zeta potential for the composite particles in different pH values indicated that the composite particles had an amphoteric property originating from VA-057 initiator.

[Fluorescent and Raman scattering by molecules embedded in small particles]: Annual report, 1983

International Nuclear Information System (INIS)

Chew, H.; McNulty, P.J.

1983-01-01

An overview is given of the model formulated for fluorescent and Raman scattering by molecules embedded in or in the vicinity of small particles. The model takes into account the size, shape, refractive index, and morphology of the host particles. Analytic and numerical results have been obtained for spherical (one and more layers, including magnetic dipole transitions), cylindrical, and spheroidal particles. Particular attention has been given to the spherical case with fluorescent/Raman scatterers uniformly distributed in the particles radiating both coherently and incoherently. Depolarization effects have been studied with suitable averaging process, and good agreement with experiment has been obtained. Analytic and numerical results have been obtained for the elastic scattering of evanescent waves; these results are useful for the study of fluorescence under excitation by evanescent waves

Cryo-imaging of fluorescently labeled single cells in a mouse

Science.gov (United States)

Steyer, Grant J.; Roy, Debashish; Salvado, Olivier; Stone, Meredith E.; Wilson, David L.

2009-02-01

We developed a cryo-imaging system to provide single-cell detection of fluorescently labeled cells in mouse, with particular applicability to stem cells and metastatic cancer. The Case cryoimaging system consists of a fluorescence microscope, robotic imaging positioner, customized cryostat, PC-based control system, and visualization/analysis software. The system alternates between sectioning (10-40 μm) and imaging, collecting color brightfield and fluorescent blockface image volumes >60GB. In mouse experiments, we imaged quantum-dot labeled stem cells, GFP-labeled cancer and stem cells, and cell-size fluorescent microspheres. To remove subsurface fluorescence, we used a simplified model of light-tissue interaction whereby the next image was scaled, blurred, and subtracted from the current image. We estimated scaling and blurring parameters by minimizing entropy of subtracted images. Tissue specific attenuation parameters were found [uT : heart (267 +/- 47.6 μm), liver (218 +/- 27.1 μm), brain (161 +/- 27.4 μm)] to be within the range of estimates in the literature. "Next image" processing removed subsurface fluorescence equally well across multiple tissues (brain, kidney, liver, adipose tissue, etc.), and analysis of 200 microsphere images in the brain gave 97+/-2% reduction of subsurface fluorescence. Fluorescent signals were determined to arise from single cells based upon geometric and integrated intensity measurements. Next image processing greatly improved axial resolution, enabled high quality 3D volume renderings, and improved enumeration of single cells with connected component analysis by up to 24%. Analysis of image volumes identified metastatic cancer sites, found homing of stem cells to injury sites, and showed microsphere distribution correlated with blood flow patterns. We developed and evaluated cryo-imaging to provide single-cell detection of fluorescently labeled cells in mouse. Our cryo-imaging system provides extreme (>60GB), micron

Single Particle Entropy in Heated Nuclei

International Nuclear Information System (INIS)

Guttormsen, M.; Chankova, R.; Hjorth-Jensen, M.; Rekstad, J.; Siem, S.; Sunde, A. C.; Syed, N. U. H.; Agvaanluvsan, U.; Schiller, A.; Voinov, A.

2006-01-01

The thermal motion of single particles represents the largest contribution to level density (or entropy) in atomic nuclei. The concept of single particle entropy is presented and shown to be an approximate extensive (additive) quantity for mid-shell nuclei. A few applications of single particle entropy are demonstrated

Fluorescence-Doped Particles for Simultaneous Temperature and Velocity Imaging

Science.gov (United States)

Danehy, Paul M.; Tiemsin, Pacita I.; Wohl, Chrostopher J.; Verkamp, Max; Lowe, T.; Maisto, P.; Byun, G.; Simpson, R.

2012-01-01

Polystyrene latex microspheres (PSLs) have been used for particle image velocimetry (PIV) and laser Doppler velocimetry (LDV) measurements for several decades. With advances in laser technologies, instrumentation, and data processing, the capability to collect more information about fluid flow beyond velocity is possible using new seed materials. To provide additional measurement capability, PSLs were synthesized with temperature-sensitive fluorescent dyes incorporated within the particle. These multifunctional PSLs would have the greatest impact if they could be used in large scale facilities with minimal modification to the facilities or the existing instrumentation. Consequently, several potential dyes were identified that were amenable to existing laser systems currently utilized in wind tunnels at NASA Langley Research Center as well as other wind and fluid (water) tunnels. PSLs incorporated with Rhodamine B, dichlorofluorescein (DCF, also known as fluorescein 548 or fluorescein 27) and other dyes were synthesized and characterized for morphology and spectral properties. The resulting particles were demonstrated to exhibit fluorescent emission, which would enable determination of both fluid velocity and temperature. They also would allow near-wall velocity measurements whereas laser scatter from surfaces currently prevents near-wall measurements using undoped seed materials. Preliminary results in a wind tunnel facility located at Virginia Polytechnic Institute and State University (Virginia Tech) have verified fluorescent signal detection and temperature sensitivity of fluorophore-doped PSLs.

3D dual-virtual-pinhole assisted single particle tracking microscopy

International Nuclear Information System (INIS)

Ma, Ye; Wang, Yifan; Zhou, Xin; Kuang, Cuifang; Liu, Xu

2014-01-01

We propose a novel approach for high-speed, three-dimensional single particle tracking (SPT), which we refer to as dual-virtual-pinhole assisted single particle tracking microscopy (DVPaSPTM). DVPaSPTM system can obtain axial information of the sample without optical or mechanical depth scanning, so as to offer numbers of advantages including faster imaging, improved efficiency and a great reduction of photobleaching and phototoxicity. In addition, by the use of the dual-virtual-pinhole, the effect that the quantum yield exerts to the fluorescent signal can be eliminated, which makes the measurement independent of the surroundings and increases the accuracy of the result. DVPaSPTM system measures the intensity within different virtual pinholes of which the radii are given by the host computer. Axial information of fluorophores can be measured by the axial response curve through the ratio of intensity signals. We demonstrated the feasibility of the proposed method by a series of experiments. Results showed that the standard deviation of the axial measurement was 19.2 nm over a 2.5 μm range with 30 ms temporal resolution. (papers)

Characterization of buoyant fluorescent particles for field observations of water flows.

Science.gov (United States)

Tauro, Flavia; Aureli, Matteo; Porfiri, Maurizio; Grimaldi, Salvatore

2010-01-01

In this paper, the feasibility of off-the-shelf buoyant fluorescent microspheres as particle tracers in turbid water flows is investigated. Microspheres' fluorescence intensity is experimentally measured and detected in placid aqueous suspensions of increasing concentrations of clay to simulate typical conditions occurring in natural drainage networks. Experiments are conducted in a broad range of clay concentrations and particle immersion depths by using photoconductive cells and image-based sensing technologies. Results obtained with both methodologies exhibit comparable trends and show that the considered particles are fairly detectable in critically turbid water flows. Further information on performance and integration of the studied microspheres in low-cost measurement instrumentation for field observations is obtained through experiments conducted in a custom built miniature water channel. This experimental characterization provides a first assessment of the feasibility of commercially available buoyant fluorescent beads in the analysis of high turbidity surface water flows. The proposed technology may serve as a minimally invasive sensing system for hazardous events, such as pollutant diffusion in natural streams and flash flooding due to extreme rainfall.

Characterization of Buoyant Fluorescent Particles for Field Observations of Water Flows

Directory of Open Access Journals (Sweden)

Flavia Tauro

2010-12-01

Full Text Available In this paper, the feasibility of off-the-shelf buoyant fluorescent microspheres as particle tracers in turbid water flows is investigated. Microspheres’ fluorescence intensity is experimentally measured and detected in placid aqueous suspensions of increasing concentrations of clay to simulate typical conditions occurring in natural drainage networks. Experiments are conducted in a broad range of clay concentrations and particle immersion depths by using photoconductive cells and image-based sensing technologies. Results obtained with both methodologies exhibit comparable trends and show that the considered particles are fairly detectable in critically turbid water flows. Further information on performance and integration of the studied microspheres in low-cost measurement instrumentation for field observations is obtained through experiments conducted in a custom built miniature water channel. This experimental characterization provides a first assessment of the feasibility of commercially available buoyant fluorescent beads in the analysis of high turbidity surface water flows. The proposed technology may serve as a minimally invasive sensing system for hazardous events, such as pollutant diffusion in natural streams and flash flooding due to extreme rainfall.

Fluorescence blinking in MEH-PPV single molecules at low temperature

International Nuclear Information System (INIS)

Mirzov, O.; Cichos, F.; Borczyskowski, C. von; Scheblykin, I.

2005-01-01

Fluorescence intensity transients of single molecules of the conjugated polymer poly[2-methoxy,5-(2'-ethylhexyloxy)-p-phenylene-vinylene] (MEH-PPV) were studied at 15 K. Fluorescence blinking behavior was observed despite the expected low-temperature suppression of energy migration in such disordered molecular systems. Presence of the fluorescence blinking effect at 15 K indicates that the single molecules possess a collapsed conformation with characteristic size of not more than several nanometers, which corresponds to only a few exciton hops over a polymer chain

Thousand-fold enhancement of single-molecule fluorescence near a single gold nanorod

NARCIS (Netherlands)

Yuan, H.; Khatua, S.; Zijlstra, P.; Yorulmaz, M.; Orrit, M.

2013-01-01

Single molecules: Large enhancements of single-molecule fluorescence up to 1100 times by using synthesized gold nanorods are reported (see picture). This high enhancement is achieved by selecting a dye with its adsorption and emission close to the surface plasmon resonance of the gold nanorods

A New Theoretical Approach to Single-Molecule Fluorescence Optical Studies of RNA Dynamics

International Nuclear Information System (INIS)

Zhao Xinghai; Shan Guangcun; Bao Shuying

2011-01-01

Single-molecule fluorescence spectroscopy in condensed phases has many important chemical and biological applications. The single-molecule fluorescence measurements contain information about conformational dynamics on a vast range of time scales. Based on the data analysis protocols methodology proposed by X. Sunney Xie, the theoretical study here mainly focuses on the single-molecule studies of single RNA with interconversions among different conformational states, to with a single FRET pair attached. We obtain analytical expressions for fluorescence lifetime correlation functions that relate changes in fluorescence lifetime to the distance-dependent FRET mechanism within the context of the Smoluchowski diffusion model. The present work establishes useful guideline for the single-molecule studies of biomolecules to reveal the complicated folding dynamics of single RNA molecules at nanometer scale.

A simple fluorescence based assay for quantification of human immunodeficiency virus particle release

Directory of Open Access Journals (Sweden)

Heuser Anke-Mareil

2010-04-01

Full Text Available Abstract Background The assembly and release of human immunodeficiency virus (HIV particles from infected cells represent attractive, but not yet exploited targets for antiretroviral therapy. The availability of simple methods to measure the efficiency of these replication steps in tissue culture would facilitate the identification of host factors essential for these processes as well as the screening for lead compounds acting as specific inhibitors of particle formation. We describe here the development of a rapid cell based assay for quantification of human immunodeficiency virus type 1 (HIV-1 particle assembly and/or release. Results Using a fluorescently labelled HIV-derivative, which carries an eYFP domain within the main viral structural protein Gag in the complete viral protein context, the release of virus like particles could be monitored by directly measuring the fluorescence intensity of the tissue culture supernatant. Intracellular Gag was quantitated in parallel by direct fluorescence analysis of cell lysates, allowing us to normalize for Gag expression efficiency. The assay was validated by comparison with p24 capsid ELISA measurements, a standard method for quantifying HIV-1 particles. Optimization of conditions allowed the robust detection of particle amounts corresponding to 50 ng p24/ml in medium by fluorescence spectroscopy. Further adaptation to a multi-well format rendered the assay suitable for medium or high throughput screening of siRNA libraries to identify host cell factors involved in late stages of HIV replication, as well as for random screening approaches to search for potential inhibitors of HIV-1 assembly or release. Conclusions The fast and simple fluorescence based quantification of HIV particle release yielded reproducible results which were comparable to the well established ELISA measurements, while in addition allowing the parallel determination of intracellular Gag expression. The protocols described here

Delivery of single accelerated particles

International Nuclear Information System (INIS)

McNulty, P.J.; Pease, V.P.; Bond, V.P.; Schimmerling, W.; Vosburgh, K.G.; Crebbin, K.; Everette, W.; Howard, J.

1978-01-01

It is desirable for certain experiments involving accelerators to have the capability of delivering just a single beam particle to the target area. The essential features of such a one-at-a-time facility are discussed. Two such facilities are described which were implemented at high-energy heavy ion accelerators without having to make major structural changes in the existing beam lines or substantially interfering with other accelerator uses. Two accelerator facilities are described which had the capability of delivering a single beam particle to the target area. This feature is necessary in certain experiments investigating visual phenomena induced by charged particles, other single particle interactions in biology, and other experiments in which the low intensities of cosmic rays need to be simulated. Both facilities were implemented without having to make structural changes in the existing beam lines or substantially interfering with other accelerator uses. (Auth.)

Real-time measurements of airborne biologic particles using fluorescent particle counter to evaluate microbial contamination: results of a comparative study in an operating theater.

Science.gov (United States)

Dai, Chunyang; Zhang, Yan; Ma, Xiaoling; Yin, Meiling; Zheng, Haiyang; Gu, Xuejun; Xie, Shaoqing; Jia, Hengmin; Zhang, Liang; Zhang, Weijun

2015-01-01

Airborne bacterial contamination poses a risk for surgical site infection, and routine surveillance of airborne bacteria is important. Traditional methods for detecting airborne bacteria are time consuming and strenuous. Measurement of biologic particle concentrations using a fluorescent particle counter is a novel method for evaluating air quality. The current study was to determine whether the number of biologic particles detected by the fluorescent particle counter can be used to indicate airborne bacterial counts in operating rooms. The study was performed in an operating theater at a university hospital in Hefei, China. The number of airborne biologic particles every minute was quantified using a fluorescent particle counter. Microbiologic air sampling was performed every 30 minutes using an Andersen air sampler (Pusong Electronic Instruments, Changzhou, China). Correlations between the 2 different methods were analyzed by Pearson correlation coefficients. A significant correlation was observed between biologic particle and bacterial counts (Pearson correlation coefficient = 0.76), and the counting results from 2 methods both increased substantially between operations, corresponding with human movements in the operating room. Fluorescent particle counters show potential as important tools for monitoring bacterial contamination in operating theatres. Copyright © 2015 Association for Professionals in Infection Control and Epidemiology, Inc. Published by Elsevier Inc. All rights reserved.

Optical probing of single fluorescent molecules and proteins

NARCIS (Netherlands)

Garcia Parajo, M.F.; Veerman, J.A.; Bouwhuis, R.; Bouwhuis, Rudo; van Hulst, N.F.; Vallée, R.A.L.

2001-01-01

Single-molecule detection and analysis of organic fluorescent molecules and proteins are presented, with emphasis o­n the underlying principles methodology and the application of single-molecule analysis at room temperature. This Minireview is mainly focused o­n the application of confocal and

Single-particle dispersion in compressible turbulence

Science.gov (United States)

Zhang, Qingqing; Xiao, Zuoli

2018-04-01

Single-particle dispersion statistics in compressible box turbulence are studied using direct numerical simulation. Focus is placed on the detailed discussion of effects of the particle Stokes number and turbulent Mach number, as well as the forcing type. When solenoidal forcing is adopted, it is found that the single-particle dispersion undergoes a transition from the ballistic regime at short times to the diffusive regime at long times, in agreement with Taylor's particle dispersion argument. The strongest dispersion of heavy particles is announced when the Stokes number is of order 1, which is similar to the scenario in incompressible turbulence. The dispersion tends to be suppressed as the Mach number increases. When hybrid solenoidal and compressive forcing at a ratio of 1/2 is employed, the flow field shows apparent anisotropic property, characterized by the appearance of large shock wave structures. Accordingly, the single-particle dispersion shows extremely different behavior from the solenoidal forcing case.

Single-particle potential from resummed ladder diagrams

International Nuclear Information System (INIS)

Kaiser, N.

2013-01-01

A recent work on the resummation of fermionic in-medium ladder diagrams to all orders is extended by calculating the complex single-particle potential U(p, k f ) + i W(p, k f ) p > k f . The on-shell single-particle potential is constructed by means of a complex-valued in-medium loop that includes corrections from a test particle of momentum vector p added to the filled Fermi sea. The single-particle potential U(k f , k f ) at the Fermi surface as obtained from the resummation of the combined particle and hole ladder diagrams is shown to satisfy the Hugenholtz-Van-Hove theorem. The perturbative contributions at various orders a n in the scattering length are deduced and checked against the known analytical results at order a 1 and a 2 . The limit a → ∞ is studied as a special case and a strong momentum dependence of the real (and imaginary) single-particle potential is found. This feature indicates an instability against a phase transition to a state with an empty shell inside the Fermi sphere such that the density gets reduced by about 5%. The imaginary single-particle potential vanishes linearly at the Fermi surface. For comparison, the same analysis is performed for the resummed particle-particle ladder diagrams alone. In this truncation an instability for hole excitations near the Fermi surface is found at strong coupling. For the set of particle-hole ring diagrams the single-particle potential is calculated as well. Furthermore, the resummation of in-medium ladder diagrams to all orders is studied for a two-dimensional Fermi gas with a short-range two-body contact interaction. (orig.)

Single particle distributions, ch.2

International Nuclear Information System (INIS)

Blokzijl, R.

1977-01-01

A survey of inclusive single particle distributions is given for various particles. A comparison of particle cross-sections measured in K - p experiments at different center of mass energies shows that some of these cross-sections remain almost constant over a wide range of incoming K - momenta

A single-chip computer analysis system for liquid fluorescence

International Nuclear Information System (INIS)

Zhang Yongming; Wu Ruisheng; Li Bin

1998-01-01

The single-chip computer analysis system for liquid fluorescence is an intelligent analytic instrument, which is based on the principle that the liquid containing hydrocarbons can give out several characteristic fluorescences when irradiated by strong light. Besides a single-chip computer, the system makes use of the keyboard and the calculation and printing functions of a CASIO printing calculator. It combines optics, mechanism and electronics into one, and is small, light and practical, so it can be used for surface water sample analysis in oil field and impurity analysis of other materials

Convergence of lateral dynamic measurements in the plasma membrane of live cells from single particle tracking and STED-FCS

DEFF Research Database (Denmark)

Lagerholm, B. Christoffer; Andrade, Débora M.; Clausen, Mathias P.

2017-01-01

Fluorescence correlation spectroscopy (FCS) in combination with the super-resolution imaging method STED (STED-FCS), and single-particle tracking (SPT) are able to directly probe the lateral dynamics of lipids and proteins in the plasma membrane of live cells at spatial scales much below the diff...

Spectroscopy and nonclassical fluorescence properties of single trapped Ba+ ions

International Nuclear Information System (INIS)

Bolle, J.

1998-06-01

This thesis reports on the setup and application of an experimental apparatus for spectroscopic and quantum optical investigations of a single Barium ion in a Paul trap. The realization of the apparatus, which consists of the ion trap in ultra high vacuum, two laser systems, and a photon counting detection system, is described in detail, with particular consideration of the noise sources like stray light and laser frequency instabilities. The two lasers at 493 nm and 650 nm needed to continuously excite resonance fluorescence from the Barium ion have been realized using diode lasers only. The preparation of a single localized Barium ion is described, in particular its optical cooling with the laser light and the minimization of induced vibration in the trapping potential. The purely quantum mechanical property of antibunching is observed by measuring the intensity correlation function of resonance fluorescence from the trapped and cooled ion. Interference properties of the single ion resonance fluorescence are investigated with a Mach-Zehnder interferometer. From the measured high-contrast interference signal it is proven that each individual fluorescence photon interferes with itself. The fluorescence excitation spectrum, on varying one laser frequency, is also measured and exhibits dark resonances. These measurements are compared to calculations based on optical Bloch equations for the 8 atomic levels involved. Future experiments, in particular the detection of reduced quantum fluctuations (squeezing) in one quadrature component of the resonance fluorescence, are discussed. (author)

Synthesis and characterization of monodisperse, mesoporous, and magnetic sub-micron particles doped with a near-infrared fluorescent dye

International Nuclear Information System (INIS)

Le Guevel, Xavier; Nooney, Robert; McDonagh, Colette; MacCraith, Brian D.

2011-01-01

Recently, multifunctional silica nanoparticles have been investigated extensively for their potential use in biomedical applications. We have prepared sub-micron monodisperse and stable multifunctional mesoporous silica particles with a high level of magnetization and fluorescence in the near infrared region using an one-pot synthesis technique. Commercial magnetite nanocrystals and a conjugated-NIR-dye were incorporated inside the particles during the silica condensation reaction. The particles were then coated with polyethyleneglycol to stop aggregation. X-ray diffraction, N 2 adsorption analysis, TEM, fluorescence and absorbance measurements were used to structurally characterize the particles. These mesoporous silica spheres have a large surface area (1978 m 2 /g) with 3.40 nm pore diameter and a high fluorescence in the near infrared region at λ=700 nm. To explore the potential of these particles for drug delivery applications, the pore accessibility to hydrophobic drugs was simulated by successfully trapping a hydrophobic ruthenium dye complex inside the particle with an estimated concentration of 3 wt%. Fluorescence imaging confirmed the presence of both NIR dye and the post-grafted ruthenium dye complex inside the particles. These particles moved at approximately 150 μm/s under the influence of a magnetic field, hence demonstrating the multifunctionality and potential for biomedical applications in targeting and imaging. - Graphical Abstract: Hydrophobic fluorescent Ruthenium complex has been loaded into the mesopores as a surrogate drug to simulate drug delivery and to enhance the multifunctionality of the magnetic NIR emitting particles. Highlights: → Monodisperse magnetic mesoporous silica particles emitting in the near infrared region are obtained in one-pot synthesis. → We prove the capacity of such particles to uptake hydrophobic dye to mimic drug loading. → Loaded fluorescent particles can be moved under a magnetic field in a microfluidic

Single-particle colloid tracking in four dimensions.

Science.gov (United States)

Anthony, Stephen M; Hong, Liang; Kim, Minsu; Granick, Steve

2006-11-21

Coating a close-packed fluorescent colloid monolayer with a nanometer-thick metal film followed by sonication in liquid produces modulated optical nanoprobes. The metal coating modulates the fluorescence as these structures rotate in suspension, enabling the use of these particles as probes to monitor both rotational and center-of-mass (translational) dynamics in complex environments. Here, we demonstrate methods to simultaneously measure two translational and two rotational degrees of freedom, with excellent agreement to theory. The capability to determine two angles of rotation opens several new avenues of future research.

Improved Dye Stability in Single-Molecule Fluorescence Experiments

Science.gov (United States)

EcheverrÍa Aitken, Colin; Marshall, R. Andrew; Pugi, Joseph D.

Complex biological systems challenge existing single-molecule methods. In particular, dye stability limits observation time in singlemolecule fluorescence applications. Current approaches to improving dye performance involve the addition of enzymatic oxygen scavenging systems and small molecule additives. We present an enzymatic oxygen scavenging system that improves dye stability in single-molecule experiments. Compared to the currently-employed glucose-oxidase/catalase system, the protocatechuate-3,4-dioxygenase system achieves lower dissolved oxygen concentration and stabilizes single Cy3, Cy5, and Alexa488 fluorophores. Moreover, this system possesses none of the limitations associated with the glucose oxidase/catalase system. We also tested the effects of small molecule additives in this system. Biological reducing agents significantly destabilize the Cy5 fluorophore as a function of reducing potential. In contrast, anti-oxidants stabilize the Cy3 and Alexa488 fluorophores. We recommend use of the protocatechuate-3,4,-dioxygenase system with antioxidant additives, and in the absence of biological reducing agents. This system should have wide application to single-molecule fluorescence experiments.

X-ray analysis of a single aerosol particle with combination of scanning electron microscope and synchrotron radiation X-ray microscope

International Nuclear Information System (INIS)

Toyoda, Masatoshi; Kaibuchi, Kazuki; Nagasono, Mitsuru; Terada, Yasuko; Tanabe, Teruo; Hayakawa, Shinjiro; Kawai, Jun

2004-01-01

We developed a microscope by a combination of synchrotron radiation X-ray fluorescence (SR-XRF) microscope and scanning electron microscope (SEM) with an energy dispersive X-ray spectrometer (EDX). SR-XRF is appropriate to detect trace and micro amount of elements and sensitive to heavy elements in an analyte but it cannot observe the real time image. SEM-EDX can observe the secondary electron image of a single particle in real time and is appropriate to detect lighter elements. This combination microscope can ensure the identification of the XRF spectrum to the SEM image without transferring the sample. For aerosol analysis, it is important to analyze each particle. The present method makes feasible to analyze not only the average elemental composition as the total particles but also elemental composition of each particle, which is dependent on the particle shape and size. The microscope was applied to an individual aerosol particle study. The X-ray spectra were different among the particles, but also different between SR-XRF and SEM-EDX for the same particle, due to the difference in fluorescence yields between X-ray excitation and electron excitation

Orbital single particle tracking on a commercial confocal microscope using piezoelectric stage feedback

International Nuclear Information System (INIS)

Lanzanò, L; Gratton, E

2014-01-01

Single Particle Tracking (SPT) is a technique used to locate fluorescent particles with nanometer precision. In the orbital tracking method the position of a particle is obtained analyzing the distribution of intensity along a circular orbit scanned around the particle. In combination with an active feedback this method allows tracking of particles in 2D and 3D with millisecond temporal resolution. Here we describe a SPT setup based on a feedback approach implemented with minimal modification of a commercially available confocal laser scanning microscope, the Zeiss LSM 510, in combination with an external piezoelectric stage scanner. The commercial microscope offers the advantage of a user-friendly software interface and pre-calibrated hardware components. The use of an external piezo-scanner allows the addition of feedback into the system but also represents a limitation in terms of its mechanical response. We describe in detail this implementation of the orbital tracking method and discuss advantages and limitations. As an example of application to live cell experiments we perform the 3D tracking of acidic vesicles in live polarized epithelial cells. (paper)

Precision analysis for standard deviation measurements of immobile single fluorescent molecule images.

Science.gov (United States)

DeSantis, Michael C; DeCenzo, Shawn H; Li, Je-Luen; Wang, Y M

2010-03-29

Standard deviation measurements of intensity profiles of stationary single fluorescent molecules are useful for studying axial localization, molecular orientation, and a fluorescence imaging system's spatial resolution. Here we report on the analysis of the precision of standard deviation measurements of intensity profiles of single fluorescent molecules imaged using an EMCCD camera.We have developed an analytical expression for the standard deviation measurement error of a single image which is a function of the total number of detected photons, the background photon noise, and the camera pixel size. The theoretical results agree well with the experimental, simulation, and numerical integration results. Using this expression, we show that single-molecule standard deviation measurements offer nanometer precision for a large range of experimental parameters.

Circumvention of fluorophore photobleaching in fluorescence fluctuation experiments: a beam scanning approach.

Science.gov (United States)

Satsoura, Dmitri; Leber, Brian; Andrews, David W; Fradin, Cécile

2007-04-23

Photobleaching is a fluorophore-damaging process that commonly afflicts single-molecule fluorescence studies. It becomes an especially severe problem in fluorescence fluctuation experiments when studying slowly diffusing particles. One way to circumvent this problem is to use beam scanning to decrease the residence time of the fluorophores in the excitation volume. We report a systematic study of the effects of circular beam scanning on the photobleaching of fluorescent particles as observed in single-photon excitation fluorescence fluctuation experiments. We start by deriving a simple expression relating the average detected fluorescence to the photobleaching cross section of the fluorophores. We then perform numerical calculations of the spatial distribution of fluorescent particles in order to understand under which conditions beam scanning can prevent the formation of a photobleaching hole. To support these predictions, we show experimental results obtained for large unilamellar vesicles containing a small amount of the fluorescent lipophilic tracer DiD. We establish the required scanning radius and frequency range in order to obtain sufficient reduction of the photobleaching effect for that system. From the detected increase in fluorescence upon increase in scanning speed, we estimate the photobleaching cross section of DiD.

Fluorescent single walled nanotube/silica composite materials

Science.gov (United States)

Dattelbaum, Andrew M.; Gupta, Gautam; Duque, Juan G.; Doorn, Stephen K.; Hamilton, Christopher E.; DeFriend Obrey, Kimberly A.

2013-03-12

Fluorescent composites of surfactant-wrapped single-walled carbon nanotubes (SWNTs) were prepared by exposing suspensions of surfactant-wrapped carbon nanotubes to tetramethylorthosilicate (TMOS) vapor. Sodium deoxycholate (DOC) and sodium dodecylsulphate (SDS) were the surfactants. No loss in emission intensity was observed when the suspension of DOC-wrapped SWNTs were exposed to the TMOS vapors, but about a 50% decrease in the emission signal was observed from the SDS-wrapped SWNTs nanotubes. The decrease in emission was minimal by buffering the SDS/SWNT suspension prior to forming the composite. Fluorescent xerogels were prepared by adding glycerol to the SWNT suspensions prior to TMOS vapor exposure, followed by drying the gels. Fluorescent aerogels were prepared by replacing water in the gels with methanol and then exposing them to supercritical fluid drying conditions. The aerogels can be used for gas sensing.

Hybrid confocal Raman fluorescence microscopy on single cells using semiconductor quantum dots

NARCIS (Netherlands)

van Manen, H.J.; Otto, Cornelis

2007-01-01

We have overcome the traditional incompatibility of Raman microscopy with fluorescence microscopy by exploiting the optical properties of semiconductor fluorescent quantum dots (QDs). Here we present a hybrid Raman fluorescence spectral imaging approach for single-cell microscopy applications. We

Click strategies for single-molecule protein fluorescence.

Science.gov (United States)

Milles, Sigrid; Tyagi, Swati; Banterle, Niccolò; Koehler, Christine; VanDelinder, Virginia; Plass, Tilman; Neal, Adrian P; Lemke, Edward A

2012-03-21

Single-molecule methods have matured into central tools for studies in biology. Foerster resonance energy transfer (FRET) techniques, in particular, have been widely applied to study biomolecular structure and dynamics. The major bottleneck for a facile and general application of these studies arises from the need to label biological samples site-specifically with suitable fluorescent dyes. In this work, we present an optimized strategy combining click chemistry and the genetic encoding of unnatural amino acids (UAAs) to overcome this limitation for proteins. We performed a systematic study with a variety of clickable UAAs and explored their potential for high-resolution single-molecule FRET (smFRET). We determined all parameters that are essential for successful single-molecule studies, such as accessibility of the probes, expression yield of proteins, and quantitative labeling. Our multiparameter fluorescence analysis allowed us to gain new insights into the effects and photophysical properties of fluorescent dyes linked to various UAAs for smFRET measurements. This led us to determine that, from the extended tool set that we now present, genetically encoding propargyllysine has major advantages for state-of-the-art measurements compared to other UAAs. Using this optimized system, we present a biocompatible one-step dual-labeling strategy of the regulatory protein RanBP3 with full labeling position freedom. Our technique allowed us then to determine that the region encompassing two FxFG repeat sequences adopts a disordered but collapsed state. RanBP3 serves here as a prototypical protein that, due to its multiple cysteines, size, and partially disordered structure, is not readily accessible to any of the typical structure determination techniques such as smFRET, NMR, and X-ray crystallography.

Saha equation, single and two particle states

International Nuclear Information System (INIS)

Kraeft, W.D.; Girardeau, M.D.; Strege, B.

1990-01-01

Single and two particle porperties in dense plasma are discussed in connection with their role in the mass action law for a partially ionized plasma. The two particle bound states are nearly density independent, while the continuum is essentially shifted. The single particle states are damped, and their energy has a negative shift and a parabolic behaviour for small momenta. (orig.)

Quantifying the number of color centers in single fluorescent nanodiamonds by photon correlation spectroscopy and Monte Carlo simulation

International Nuclear Information System (INIS)

Hui, Y.Y.; Chang, Y.-R.; Lee, H.-Y.; Chang, H.-C.; Lim, T.-S.; Fann Wunshain

2009-01-01

The number of negatively charged nitrogen-vacancy centers (N-V) - in fluorescent nanodiamond (FND) has been determined by photon correlation spectroscopy and Monte Carlo simulations at the single particle level. By taking account of the random dipole orientation of the multiple (N-V) - fluorophores and simulating the probability distribution of their effective numbers (N e ), we found that the actual number (N a ) of the fluorophores is in linear correlation with N e , with correction factors of 1.8 and 1.2 in measurements using linearly and circularly polarized lights, respectively. We determined N a =8±1 for 28 nm FND particles prepared by 3 MeV proton irradiation

Single-Walled Carbon Nanotubes as Fluorescence Biosensors for Pathogen Recognition in Water Systems

Directory of Open Access Journals (Sweden)

Venkata K. K. Upadhyayula

2008-01-01

Full Text Available The possibility of using single-walled carbon nanotubes (SWCNTs aggregates as fluorescence sensors for pathogen recognition in drinking water treatment applications has been studied. Batch adsorption study is conducted to adsorb large concentrations of Staphylococcus aureus aureus SH 1000 and Escherichia coli pKV-11 on single-walled carbon nanotubes. Subsequently the immobilized bacteria are detected with confocal microscopy by coating the nanotubes with fluorescence emitting antibodies. The Freundlich adsorption equilibrium constant (k for S.aureus and E.coli determined from batch adsorption study was found to be 9×108 and 2×108 ml/g, respectively. The visualization of bacterial cells adsorbed on fluorescently modified carbon nanotubes is also clearly seen. The results indicate that hydrophobic single-walled carbon nanotubes have excellent bacterial adsorption capacity and fluorescent detection capability. This is an important advancement in designing fluorescence biosensors for pathogen recognition in water systems.

Systematic characterization and fluorescence threshold strategies for the wideband integrated bioaerosol sensor (WIBS) using size-resolved biological and interfering particles

Science.gov (United States)

Savage, Nicole J.; Krentz, Christine E.; Könemann, Tobias; Han, Taewon T.; Mainelis, Gediminas; Pöhlker, Christopher; Huffman, J. Alex

2017-11-01

Atmospheric particles of biological origin, also referred to as bioaerosols or primary biological aerosol particles (PBAP), are important to various human health and environmental systems. There has been a recent steep increase in the frequency of published studies utilizing commercial instrumentation based on ultraviolet laser/light-induced fluorescence (UV-LIF), such as the WIBS (wideband integrated bioaerosol sensor) or UV-APS (ultraviolet aerodynamic particle sizer), for bioaerosol detection both outdoors and in the built environment. Significant work over several decades supported the development of the general technologies, but efforts to systematically characterize the operation of new commercial sensors have remained lacking. Specifically, there have been gaps in the understanding of how different classes of biological and non-biological particles can influence the detection ability of LIF instrumentation. Here we present a systematic characterization of the WIBS-4A instrument using 69 types of aerosol materials, including a representative list of pollen, fungal spores, and bacteria as well as the most important groups of non-biological materials reported to exhibit interfering fluorescent properties. Broad separation can be seen between the biological and non-biological particles directly using the five WIBS output parameters and by taking advantage of the particle classification analysis introduced by Perring et al. (2015). We highlight the importance that particle size plays on observed fluorescence properties and thus in the Perring-style particle classification. We also discuss several particle analysis strategies, including the commonly used fluorescence threshold defined as the mean instrument background (forced trigger; FT) plus 3 standard deviations (σ) of the measurement. Changing the particle fluorescence threshold was shown to have a significant impact on fluorescence fraction and particle type classification. We conclude that raising the

Single-particle Glauber matrix elements

International Nuclear Information System (INIS)

Oset, E.; Strottman, D.

1983-01-01

The single-particle matrix elements of the Glauber profile function are tabulated for harmonic oscillator single-particle wave functions. The tables are presented in such a manner as to be applicable if the hadron--nucleon elementary scattering amplitude is specified by either a partial wave expansion or a Gaussian in momentum transfer squared. The table is complete through the 1 g/sub 9/2/ orbital and contains entries for the 3s/sub 1/2/ orbital for use if realistic wave functions are expanded in terms of harmonic oscillator functions

Fluorescent scattering by molecules embedded in small particles. Progress report, May 1, 1977--October 31, 1978

International Nuclear Information System (INIS)

Chew, H.; McNulty, P.J.

1978-01-01

A model for the fluorescence and Raman scattering by molecules that comprise or are embedded in small particles was developed and numerical calculations performed. The emphasis during this first year of the contract was on writing and testing the computer programs necessary for numerical calculations and on demonstrating the extent of the potential effects that the geometrical and optical properties of the particle would have on the Raman and fluorescent emissions. For the purpose of demonstrating effects emphasis was focused upon the case of isotropically polarizable molecules that fluoresce or Raman scatter through electric dipole transitions. Some preliminary results are described. One result of these investigations that is of particular significance for remote sensing of pollutants is that it would be a serious mistake to use inelastic scattering techniques such as Raman and fluorescent scattering for quantitative assay of specific molecules in aerosols containing particulates without taking into account the size, structure and refractive index of the particles. A list of publications is included

Single Molecule Fluorescence: from Physical Fascination to Biological Relevance

OpenAIRE

Segers-Nolten, Gezina M.J.

2003-01-01

Confocal fluorescence microscopy is particularly well-known from the beautiful images that have been obtained with this technique from cells. Several cellular components could be nicely visualized simultaneously by staining them with different fluorophores. Not only for ensemble applications but also in single molecule research confocal fluorescence microscopy became a popular technique. In this thesis the possibilities are shown to study a complicated biological process, which is Nucleotide ...

Accumulative difference image protocol for particle tracking in fluorescence microscopy tested in mouse lymphonodes.

Science.gov (United States)

Villa, Carlo E; Caccia, Michele; Sironi, Laura; D'Alfonso, Laura; Collini, Maddalena; Rivolta, Ilaria; Miserocchi, Giuseppe; Gorletta, Tatiana; Zanoni, Ivan; Granucci, Francesca; Chirico, Giuseppe

2010-08-17

The basic research in cell biology and in medical sciences makes large use of imaging tools mainly based on confocal fluorescence and, more recently, on non-linear excitation microscopy. Substantially the aim is the recognition of selected targets in the image and their tracking in time. We have developed a particle tracking algorithm optimized for low signal/noise images with a minimum set of requirements on the target size and with no a priori knowledge of the type of motion. The image segmentation, based on a combination of size sensitive filters, does not rely on edge detection and is tailored for targets acquired at low resolution as in most of the in-vivo studies. The particle tracking is performed by building, from a stack of Accumulative Difference Images, a single 2D image in which the motion of the whole set of the particles is coded in time by a color level. This algorithm, tested here on solid-lipid nanoparticles diffusing within cells and on lymphocytes diffusing in lymphonodes, appears to be particularly useful for the cellular and the in-vivo microscopy image processing in which few a priori assumption on the type, the extent and the variability of particle motions, can be done.

Accumulative difference image protocol for particle tracking in fluorescence microscopy tested in mouse lymphonodes.

Directory of Open Access Journals (Sweden)

Carlo E Villa

Full Text Available The basic research in cell biology and in medical sciences makes large use of imaging tools mainly based on confocal fluorescence and, more recently, on non-linear excitation microscopy. Substantially the aim is the recognition of selected targets in the image and their tracking in time. We have developed a particle tracking algorithm optimized for low signal/noise images with a minimum set of requirements on the target size and with no a priori knowledge of the type of motion. The image segmentation, based on a combination of size sensitive filters, does not rely on edge detection and is tailored for targets acquired at low resolution as in most of the in-vivo studies. The particle tracking is performed by building, from a stack of Accumulative Difference Images, a single 2D image in which the motion of the whole set of the particles is coded in time by a color level. This algorithm, tested here on solid-lipid nanoparticles diffusing within cells and on lymphocytes diffusing in lymphonodes, appears to be particularly useful for the cellular and the in-vivo microscopy image processing in which few a priori assumption on the type, the extent and the variability of particle motions, can be done.

Functional incorporation of green fluorescent protein into hepatitis B virus envelope particles

International Nuclear Information System (INIS)

Lambert, Carsten; Thome, Nicole; Kluck, Christoph J.; Prange, Reinhild

2004-01-01

The envelope of hepatitis B virus (HBV), containing the L, M, and S proteins, is essential for virus entry and maturation. For direct visualization of HBV, we determined whether envelope assembly could accommodate the green fluorescent protein (GFP). While the C-terminal addition of GFP to S trans-dominant negatively inhibited empty envelope particle secretion, the N-terminal GFP fusion to S (GFP.S) was co-integrated into the envelope, giving rise to fluorescent particles. Microscopy and topogenesis analyses demonstrated that the proper intracellular distribution and folding of GFP.S, required for particle export were rescued by interprotein interactions with wild-type S. Thereby, a dual location of GFP, inside and outside the envelope, was observed. GFP.S was also efficiently packaged into the viral envelope, and these GFP-tagged virions retained the capacity for attachment to HBV receptor-positive cells in vitro. Together, GFP-tagged virions should be suitable to monitor HBV uptake and egress in live hepatocytes

Single-particle Schroedinger fluid. I. Formulation

International Nuclear Information System (INIS)

Kan, K.K.; Griffin, J.J.

1976-01-01

The problem of a single quantal particle moving in a time-dependent external potential well is formulated specifically to emphasize and develop the fluid dynamical aspects of the matter flow. This idealized problem, the single-particle Schroedinger fluid, is shown to exhibit already a remarkably rich variety of fluid dynamical features, including compressible flow and line vortices. It provides also a sufficient framework to encompass simultaneously various simplified fluidic models for nuclei which have earlier been postulated on an ad hoc basis, and to illuminate their underlying restrictions. Explicit solutions of the single-particle Schroedinger fluid problem are studied in the adiabatic limit for their mathematical and physical implications (especially regarding the collective kinetic energy). The basic generalizations for extension of the treatment to the many-body Schroedinger fluid are set forth

The development of optical microscopy techniques for the advancement of single-particle studies

Science.gov (United States)

Marchuk, Kyle

Single particle orientation and rotational tracking (SPORT) has recently become a powerful optical microscopy tool that can expose many molecular motions. Unfortunately, there is not yet a single microscopy technique that can decipher all particle motions in all environmental conditions, thus there are limitations to current technologies. Within, the two powerful microscopy tools of total internal reflection and interferometry are advanced to determine the position, orientation, and optical properties of metallic nanoparticles in a variety of environments. Total internal reflection is an optical phenomenon that has been applied to microscopy to produce either fluorescent or scattered light. The non-invasive far-field imaging technique is coupled with a near-field illumination scheme that allows for better axial resolution than confocal microscopy and epi-fluorescence microscopy. By controlling the incident illumination angle using total internal reflection fluorescence (TIRF) microscopy, a new type of imaging probe called "non-blinking" quantum dots (NBQDs) were super-localized in the axial direction to sub-10-nm precision. These particles were also used to study the rotational motion of microtubules being propelled by the motor protein kinesin across the substrate surface. The same instrument was modified to function under total internal reflection scattering (TIRS) microscopy to study metallic anisotropic nanoparticles and their dynamic interactions with synthetic lipid bilayers. Utilizing two illumination lasers with opposite polarization directions at wavelengths corresponding to the short and long axis surface plasmon resonance (SPR) of the nanoparticles, both the in-plane and out-of-plane movements of many particles could be tracked simultaneously. When combined with Gaussian point spread function (PSF) fitting for particle super-localization, the binding status and rotational movement could be resolved without degeneracy. TIRS microscopy was also used to

The development of optical microscopy techniques for the advancement of single-particle studies

Energy Technology Data Exchange (ETDEWEB)

Marchuk, Kyle [Iowa State Univ., Ames, IA (United States)

2013-05-15

Single particle orientation and rotational tracking (SPORT) has recently become a powerful optical microscopy tool that can expose many molecular motions. Unfortunately, there is not yet a single microscopy technique that can decipher all particle motions in all environmental conditions, thus there are limitations to current technologies. Within, the two powerful microscopy tools of total internal reflection and interferometry are advanced to determine the position, orientation, and optical properties of metallic nanoparticles in a variety of environments. Total internal reflection is an optical phenomenon that has been applied to microscopy to produce either fluorescent or scattered light. The non-invasive far-field imaging technique is coupled with a near-field illumination scheme that allows for better axial resolution than confocal microscopy and epi-fluorescence microscopy. By controlling the incident illumination angle using total internal reflection fluorescence (TIRF) microscopy, a new type of imaging probe called “non-blinking” quantum dots (NBQDs) were super-localized in the axial direction to sub-10-nm precision. These particles were also used to study the rotational motion of microtubules being propelled by the motor protein kinesin across the substrate surface. The same instrument was modified to function under total internal reflection scattering (TIRS) microscopy to study metallic anisotropic nanoparticles and their dynamic interactions with synthetic lipid bilayers. Utilizing two illumination lasers with opposite polarization directions at wavelengths corresponding to the short and long axis surface plasmon resonance (SPR) of the nanoparticles, both the in-plane and out-of-plane movements of many particles could be tracked simultaneously. When combined with Gaussian point spread function (PSF) fitting for particle super-localization, the binding status and rotational movement could be resolved without degeneracy. TIRS microscopy was also used to

Methods for forming particles from single source precursors

Science.gov (United States)

Fox, Robert V [Idaho Falls, ID; Rodriguez, Rene G [Pocatello, ID; Pak, Joshua [Pocatello, ID

2011-08-23

Single source precursors are subjected to carbon dioxide to form particles of material. The carbon dioxide may be in a supercritical state. Single source precursors also may be subjected to supercritical fluids other than supercritical carbon dioxide to form particles of material. The methods may be used to form nanoparticles. In some embodiments, the methods are used to form chalcopyrite materials. Devices such as, for example, semiconductor devices may be fabricated that include such particles. Methods of forming semiconductor devices include subjecting single source precursors to carbon dioxide to form particles of semiconductor material, and establishing electrical contact between the particles and an electrode.

Development of new photon-counting detectors for single-molecule fluorescence microscopy

Science.gov (United States)

Michalet, X.; Colyer, R. A.; Scalia, G.; Ingargiola, A.; Lin, R.; Millaud, J. E.; Weiss, S.; Siegmund, Oswald H. W.; Tremsin, Anton S.; Vallerga, John V.; Cheng, A.; Levi, M.; Aharoni, D.; Arisaka, K.; Villa, F.; Guerrieri, F.; Panzeri, F.; Rech, I.; Gulinatti, A.; Zappa, F.; Ghioni, M.; Cova, S.

2013-01-01

Two optical configurations are commonly used in single-molecule fluorescence microscopy: point-like excitation and detection to study freely diffusing molecules, and wide field illumination and detection to study surface immobilized or slowly diffusing molecules. Both approaches have common features, but also differ in significant aspects. In particular, they use different detectors, which share some requirements but also have major technical differences. Currently, two types of detectors best fulfil the needs of each approach: single-photon-counting avalanche diodes (SPADs) for point-like detection, and electron-multiplying charge-coupled devices (EMCCDs) for wide field detection. However, there is room for improvements in both cases. The first configuration suffers from low throughput owing to the analysis of data from a single location. The second, on the other hand, is limited to relatively low frame rates and loses the benefit of single-photon-counting approaches. During the past few years, new developments in point-like and wide field detectors have started addressing some of these issues. Here, we describe our recent progresses towards increasing the throughput of single-molecule fluorescence spectroscopy in solution using parallel arrays of SPADs. We also discuss our development of large area photon-counting cameras achieving subnanosecond resolution for fluorescence lifetime imaging applications at the single-molecule level. PMID:23267185

Room-temperature single-photon sources with definite circular and linear polarizations based on single-emitter fluorescence in liquid crystal hosts

International Nuclear Information System (INIS)

Winkler, Justin M; Lukishova, Svetlana G; Bissell, Luke J

2013-01-01

Definite circular and linear polarizations of room-temperature single-photon sources, which can serve as polarization bases for quantum key distribution, are produced by doping planar-aligned liquid crystal hosts with single fluorescence emitters. Chiral 1-D photonic bandgap microcavities for a single handedness of circularly polarized light were prepared from both monomeric and oligomeric cholesteric liquid crystals. Fluorescent emitters, such as nanocrystal quantum dots, nitrogen vacancy color centers in nanodiamonds, and rare-earth ions in nanocrystals, were doped into these microcavity structures and used to produce circularly polarized fluorescence of definite handedness. Additionally, we observed circularly polarized resonances in the spectrum of nanocrystal quantum dot fluorescence at the edge of the cholesteric microcavity's photonic stopband. For this polarization we obtained a ∼4.9 enhancement of intensity compared to the polarization of the opposite handedness that propagates without photonic bandgap microcavity effects. Such a resonance is indicative of coupling of quantum dot fluorescence to the cholesteric microcavity mode. We have also used planar-aligned nematic liquid crystal hosts to align DiI dye molecules doped into the host, thereby providing a single-photon source of linear polarization of definite direction. Antibunching is demonstrated for fluorescence of nanocrystal quantum dots, nitrogen vacancy color centers, and dye molecules in these liquid crystal structures.

Quantitative comparison of two particle tracking methods in fluorescence microscopy images

CSIR Research Space (South Africa)

Mabaso, M

2013-09-01

Full Text Available that cannot be analysed efficiently by means of manual analysis. In this study we compare the performance of two computer-based tracking methods for tracking of bright particles in fluorescence microscopy image sequences. The methods under comparison are...

Versatile single-molecule multi-color excitation and detection fluorescence setup for studying biomolecular dynamics

KAUST Repository

Sobhy, M. A.; Elshenawy, M. M.; Takahashi, Masateru; Whitman, B. H.; Walter, N. G.; Hamdan, S. M.

2011-01-01

Single-molecule fluorescence imaging is at the forefront of tools applied to study biomolecular dynamics both in vitro and in vivo. The ability of the single-molecule fluorescence microscope to conduct simultaneous multi-color excitation

Single-Molecule Fluorescence Studies of Membrane Transporters Using Total Internal Reflection Microscopy.

Science.gov (United States)

Goudsmits, Joris M H; van Oijen, Antoine M; Slotboom, Dirk J

2017-01-01

Cells are delineated by a lipid bilayer that physically separates the inside from the outer environment. Most polar, charged, or large molecules require proteins to reduce the energetic barrier for passage across the membrane and to achieve transport rates that are relevant for life. Here, we describe techniques to visualize the functioning of membrane transport proteins with fluorescent probes at the single-molecule level. First, we explain how to produce membrane-reconstituted transporters with fluorescent labels. Next, we detail the construction of a microfluidic flow cell to image immobilized proteoliposomes on a total internal reflection fluorescence microscope. We conclude by describing the methods that are needed to analyze fluorescence movies and obtain useful single-molecule data. © 2017 Elsevier Inc. All rights reserved.

Single-particle motion in large-amplitude quadrupole shape transition

International Nuclear Information System (INIS)

Yamada, Kazuya

1991-01-01

The microscopic structure of the single-particle motion for the spherical-deformed transitional nuclei is analysed by using the self-consistent collective-coordinate method (SCC method). The single-particle motion in the moving-frame of reference called the collective vibrating coordinate frame is introduced by the generalized Bogoliubov transformation depending on the collective coordinate. The numerical calculations of the single-particle (quasi-particle) energy level diagrams and their occupation probabilities for the static deformation are carried out for the Sm isotopes. A clear change of the single-particle distribution structure appears in the course of deformation. (author)

Visualizing Single-molecule DNA Replication with Fluorescence Microscopy

NARCIS (Netherlands)

Tanner, Nathan A.; Loparo, Joseph J.; Oijen, Antoine M. van

2009-01-01

We describe a simple fluorescence microscopy-based real-time method for observing DNA replication at the single-molecule level. A circular, forked DNA template is attached to a functionalized glass coverslip and replicated extensively after introduction of replication proteins and nucleotides. The

A simple optical fiber device for quantitative fluorescence microscopy of single living cells

NARCIS (Netherlands)

van Graft, M.; van Graft, Marja; Oosterhuis, B.; Oosterhuis, Bernard; van der Werf, Kees; de Grooth, B.G.; Greve, Jan

1993-01-01

simple and relatively inexpensive system is described for obtaining quantitative fluorescence measurements on single living cells loaded with a fluorescent probe to study cell physiological processes. The light emitted from the fluorescent cells is captured by and transported through an optical

NATO Advanced Research Workshop on Fluorescence and other Optical Properties of Biological Particles for Biological Warfare Agent Sensors

CERN Document Server

Hoekstra, Alfons; Videen, Gorden; Optics of Biological Particles

2007-01-01

This book covers the optics of single biological particles, both theory and experiment, with emphasis on Elastic Light Scattering and Fluorescence. It deals with the optics of bacteria (bio-aerosols), marine particles (selected phytoplankton communities) and red and white blood cells. Moreover, there are dedicated chapters on a general theory for scattering by a cell, and modelling and simulation of scattering by inhomogeneous biological cells. Finally, one chapter is dedicated to astro-biological signatures, discussing the possibilities for detecting non-terrestrial biological material. The volume has up-to-date discussions on new experimental and numerical techniques, and many examples of applications of these techniques in real-life systems, as used to detect and characterize e.g. biological warfare agents or human blood cells.

Enhancement of single particle rare earth doped NaYF4: Yb, Er emission with a gold shell

International Nuclear Information System (INIS)

Li, Ling; Green, Kory; Hallen, Hans; Lim, Shuang Fang

2015-01-01

Upconversion of infrared light to visible light has important implications for bioimaging. However, the small absorption cross-section of rare earth dopants has limited the efficiency of these anti-Stokes nanomaterials. We present enhanced excitation absorption and single particle fluorescent emission of sodium yttrium fluoride, NaYF 4 : Yb, Er based upconverting nanoparticles coated with a gold nanoshell through surface plasmon resonance. The single gold-shell coated nanoparticles show enhanced absorption in the near infrared, enhanced total emission intensity, and increased green relative to red emission. We also show differences in enhancement between single and aggregated gold shell nanoparticles. The surface plasmon resonance of the gold-shell coated nanoparticle is shown to be dependent on the shell thickness. In contrast to other reported results, our single particle experimental observations are corroborated by finite element calculations that show where the green/red emission enhancement occurs, and what portion of the enhancement is due to electromagnetic effects. We find that the excitation enhancement and green/red emission ratio enhancement occurs at the corners and edges of the doped emissive core. (paper)

Spatially resolved data on sediment transport: 1) field application examining fluorescent soil particle movement from tillage

Science.gov (United States)

Quinton, John; Hardy, Robert; Pates, Jacqueline; James, Michael

2017-04-01

Understanding where sediment originates from and where it travels to, in what quantities and at which rate is at the heart of many questions surrounding sediment transport. Progress towards unravelling these questions and deepening our understanding has come from a wide range of approaches, including laboratory and field experiments conducted at a variety of scales. In seeking to understand the connectivity of sources and sinks of sediment scientists have spent considerable energy in developing tracing technologies. These have included numerous studies that have relied on the chemical properties of the soil and sediment to establish source-sink connectivity, and the use of 137Ceasium, from radioactive fall-out, to map sediment redistribution. More recently there has been an upsurge in interest in the use of artificially applied soil tracers, including rare earth element oxides and magnetic minerals. However all these tracing methods have a significant drawback: they rely on the collection of samples to assess their concentration. This means that their spatial distribution cannot easily be established in situ and that the environment that is being studied is damaged by the sampling process; nor can data be collected in real time which allows a dynamic understanding of erosion and transport processes to be developed. Here we report on the field application of a fluorescent sand sized tracer at the hillslope scale during a tillage erosion experiment. Here we trialled both intensity based and particle counting methodologies for tracer enumeration. After simulating seven years of tillage on a hillslope we were able to precisely determine the distribution of the fluorescent tracer and also its incorporation and distribution within the soil profile. Single grains of tracer could be found over 35 m from the insertion point. In a second abstract we report on an application that combines novel fluorescent videography techniques with custom image processing to trace the

Single particle dynamics in circular accelerators

International Nuclear Information System (INIS)

Ruth, R.D.

1986-10-01

The purpose of this paper is to introduce the reader to the theory associated with the transverse dynamics of single particle, in circular accelerators. The discussion begins with a review of Hamiltonian dynamics and canonical transformations. The case of a single particle in a circular accelerator is considered with a discussion of non-linear terms and chromaticity. The canonical perturbation theory is presented and nonlinear resonances are considered. Finally, the concept of renormalization and residue criterion are examined. (FI)

Single-Walled Carbon Nano tubes as Fluorescence Biosensors for Pathogen Recognition in Water Systems

International Nuclear Information System (INIS)

Upadhyayula, V.K.K

2008-01-01

The possibility of using single-walled carbon nanotubes (SWCNTs) aggregates as fluorescence sensors for pathogen recognition in drinking water treatment applications has been studied. Batch adsorption study is conducted to adsorb large concentrations of Staphylococcus aureus aureus SH 1000 and Escherichia coli pKV-11 on single-walled carbon nanotubes. Subsequently the immobilized bacteria are detected with confocal microscopy by coating the nanotubes with fluorescence emitting antibodies. The Freundlich adsorption equilibrium constant (k) for S.aureus and E.coli determined from batch adsorption study was found to be 9 x108 and 2 x108 ml/g, respectively. The visualization of bacterial cells adsorbed on fluorescently modified carbon nanotubes is also clearly seen. The results indicate that hydrophobic single-walled carbon nanotubes have excellent bacterial adsorption capacity and fluorescent detection capability. This is an important advancement in designing fluorescence biosensors for pathogen recognition in water systems.

Fundamental study of single biomass particle combustion

Energy Technology Data Exchange (ETDEWEB)

Momeni, M.

2013-06-01

This thesis is a comprehensive study of single biomass particle combustion. The effect of particle shape and size and operating conditions on biomass conversion characteristics were investigated experimentally and theoretically. The experimental samples were divided in two groups: particles with regular shapes (spheres and cylinders) and particles with irregular shapes (almost flake-like). A CAMSIZER analyser (Retsch Technology GMBH) was used to determine the size and shape of the particles via Dynamical Digital Image Processing. The experiments were performed in a single particle reactor under well-defined conditions, and the complete combustion processes were recorded as video sequences by a CCD camera installed in the set-up. One of the project objectives is to simulate conditions reasonably close to the conditions in a power plant boiler, i.e., reasonably high temperatures (up to 1600 deg. C) and varying oxygen concentrations in the 5 to 20% range. A one-dimensional mathematical model was used to simulate all the intraparticle conversion processes (drying, recondensation, devolatilisation, char gasification/oxidation and heat/mass/momentum transfer) within single particles of different shapes and size under various conditions. The model also predicts the flame layer domain of a single particle. The model was validated by experimental results under different conditions; good agreement between the model predictions and the experimental data was observed. Both the experimental and modelling results showed that cylindrical particles lose mass faster than spherical particles of a similar volume (mass) and that the burnout time is reduced by increasing the particle aspect ratio (surface area to volume ratio). Very similar conversion times were observed for cylindrical particles with nearly identical surface area to volume ratios. Similar conversion times were also observed for two size classes of pulverised particles (with irregular shapes) made from the same type of

Distribution of lead in single atmospheric particles

Science.gov (United States)

Murphy, D. M.; Hudson, P. K.; Cziczo, D. J.; Gallavardin, S.; Froyd, K. D.; Johnston, M. V.; Middlebrook, A. M.; Reinard, M. S.; Thomson, D. S.; Thornberry, T.; Wexler, A. S.

2007-06-01

Three independent single particle mass spectrometers measured Pb in individual aerosol particles. These data provide unprecedented sensitivity and statistical significance for the measurement of Pb in single particles. This paper explores the reasons for the frequency of Pb in fine particles now that most gasoline is unleaded. Trace amounts of Pb were found in 5 to 25% of 250 to 3000 nm diameter particles sampled by both aircraft and surface instruments in the eastern and western United States. Over 5% of particles at a mountain site in Switzerland contained Pb. Particles smaller than 100 nm with high Pb content were also observed by an instrument that was only operated in urban areas. Lead was found on all types of particles, including Pb present on biomass burning particles from remote fires. Less common particles with high Pb contents contributed a majority of the total amount of Pb. Single particles with high Pb content often also contained alkali metals, Zn, Cu, Sn, As, and Sb. The association of Pb with Zn and other metals is also found in IMPROVE network filter data from surface sites. Sources of airborne Pb in the United States are reviewed for consistency with these data. The frequent appearance of trace Pb is consistent with widespread emissions of fine Pb particles from combustion sources followed by coagulation with larger particles during long-range transport. Industrial sources that directly emit Pb-rich particles also contribute to the observations. Clean regions of the western United States show some transport of Pb from Asia but most Pb over the United States comes from North American sources. Resuspension of Pb from soil contaminated by the years of leaded gasoline was not directly apparent.

Distribution of lead in single atmospheric particles

Directory of Open Access Journals (Sweden)

D. M. Murphy

2007-06-01

Full Text Available Three independent single particle mass spectrometers measured Pb in individual aerosol particles. These data provide unprecedented sensitivity and statistical significance for the measurement of Pb in single particles. This paper explores the reasons for the frequency of Pb in fine particles now that most gasoline is unleaded. Trace amounts of Pb were found in 5 to 25% of 250 to 3000 nm diameter particles sampled by both aircraft and surface instruments in the eastern and western United States. Over 5% of particles at a mountain site in Switzerland contained Pb. Particles smaller than 100 nm with high Pb content were also observed by an instrument that was only operated in urban areas. Lead was found on all types of particles, including Pb present on biomass burning particles from remote fires. Less common particles with high Pb contents contributed a majority of the total amount of Pb. Single particles with high Pb content often also contained alkali metals, Zn, Cu, Sn, As, and Sb. The association of Pb with Zn and other metals is also found in IMPROVE network filter data from surface sites. Sources of airborne Pb in the United States are reviewed for consistency with these data. The frequent appearance of trace Pb is consistent with widespread emissions of fine Pb particles from combustion sources followed by coagulation with larger particles during long-range transport. Industrial sources that directly emit Pb-rich particles also contribute to the observations. Clean regions of the western United States show some transport of Pb from Asia but most Pb over the United States comes from North American sources. Resuspension of Pb from soil contaminated by the years of leaded gasoline was not directly apparent.

Measurements of the Ultraviolet Fluorescence Cross Sections and Spectra of Bacillus Anthracis Simulants

Energy Technology Data Exchange (ETDEWEB)

Stephens, J.R.

1998-09-01

Measurements of the ultraviolet autofluorescence spectra and absolute cross sections of the Bacillus anthracis (Ba) simulants Bacillus globigii (Bg), Bacillus megaterium (Bm), Bacillus subtilis (Bs), and Bacillus cereus (Bc) were measured. Fluorescence spectra and cross sections of pine pollen (Pina echinata) were measured for comparison. Both dried vegetative cells and spores separated from the sporulated vegetative material were studied. The spectra were obtained by suspending a small number (<10) of particles in air in our Single Particle Spectroscopy Apparatus (SPSA), illuminating the particles with light from a spectrally filtered arc lamp, and measuring the fluorescence spectra of the particles. The illumination was 280 nm (20 nm FWHM) and the fluorescence spectra was measured between 300 and 450 nm. The fluorescence cross section of vegetative Bg peaks at 320 nm with a maximum cross section of 5 X 10{sup -14} cm{sup 2}/sr-nm-particle while the Bg spore fluorescence peaks at 310 nm with peak fluorescence of 8 X 10{sup -15} cm{sup 2}/sr-nm-particle. Pine pollen particles showed a higher fluorescence peaking at 355 nm with a cross section of 1.7 X 10{sup -13} cm{sup 2}/sr-nm-particle. Integrated cross sections ranged from 3.0 X 10{sup -13} for the Bg spores through 2.25 X 10{sup -12} (cm{sup 2}/sr-particle) for the vegetative cells.

Using artificial fluorescent particles as tracers of livestock wastes within an agricultural catchment

International Nuclear Information System (INIS)

Granger, Steve J.; Bol, Roland; Hawkins, Jane M.B.; White, Sue M.; Naden, Pamela S.; Old, Gareth H.; Marsh, Jon K.; Bilotta, Gary S.; Brazier, Richard E.; Macleod, Christopher J.A.; Haygarth, Philip M.

2011-01-01

Evidence for the movement of agricultural slurry and associated pollutants into surface waters is often anecdotal, particularly with relation to its 'particulate' components which receive less attention than 'bio-available' soluble phases. To assess the extent of movement of slurry particles artificial fluorescent particles were mixed with slurry and applied to a field sub-catchment within a headwater catchment. Particles were 2-60 μm in diameter and two different densities, 2.7 and 1.2 g cm -3 representing 'inorganic' and 'organic' material. Water samples from the field and catchment outlet were collected during two storm events following slurry application and analysed for particle and suspended sediment concentrations (SSC). SSC from the field and catchment outlet always formed clockwise hysteresis loops indicating sediment exhaustion and particles of the two densities were always found to be positively correlated. Particles from the field formed clockwise hysteresis loops during the first discharge event after slurry application, but anti-clockwise hysteresis loops during the second monitored event which indicated a depletion of readily mobilisable particles. Particles from the catchment outlet always formed anticlockwise hysteresis loops. Particle size became finer spatially, between field and catchment outlet, and temporally, between successive storm events. The results indicate that slurry particles may be readily transported within catchments but that different areas may contribute to pollutant loads long after the main peak in SSC has passed. The density of the particles did not appear to have any effect on particle transport however the size of the particles may play a more important role in the 2-60 μm range. - Research Highlights: → This study traces the movement of agricultural slurry particles from land to waters. → Two densities of artificial fluorescent particles were applied to a nested catchment. → Slurry particles moved from point of

Multifunctional Fluorescent-Magnetic Polymeric Colloidal Particles: Preparations and Bioanalytical Applications.

Science.gov (United States)

Kaewsaneha, Chariya; Tangboriboonrat, Pramuan; Polpanich, Duangporn; Elaissari, Abdelhamid

2015-10-28

Fluorescent-magnetic particles (FMPs) play important roles in modern materials, especially as nanoscale devices in the biomedical field. The interesting features of FMPs are attributed to their dual detection ability, i.e., fluorescent and magnetic modes. Functionalization of FMPs can be performed using several types of polymers, allowing their use in various applications. The synergistic potentials for unique multifunctional, multilevel targeting nanoscale devices as well as combination therapies make them particularly attractive for biomedical applications. However, the synthesis of FMPs is challenging and must be further developed. In this review article, we summarized the most recent representative works on polymer-based FMP systems that have been applied particularly in the bioanalytical field.

Synthesis and characterization of photoswitchable fluorescent silica nanoparticles.

Science.gov (United States)

Fölling, Jonas; Polyakova, Svetlana; Belov, Vladimir; van Blaaderen, Alfons; Bossi, Mariano L; Hell, Stefan W

2008-01-01

We have designed and synthesized a new functional (amino reactive) highly efficient fluorescent molecular switch (FMS) with a photochromic diarylethene and a rhodamine fluorescent dye. The reactive group in this FMS -N-hydroxysuccinimide ester- allows selective labeling of amino containing molecules or other materials. In ethanolic solutions, the compound displays a large fluorescent quantum yield of 52 % and a large fluorescence modulation ratio (94 %) between two states that may be interconverted with red and near-UV light. Silica nanoparticles incorporating the new FMS were prepared and characterized, and their spectroscopic and switching properties were also studied. The dye retained its properties after the incorporation into the silica, thereby allowing light-induced reversible high modulation of the fluorescence signal of a single particle for up to 60 cycles, before undergoing irreversible photobleaching. Some applications of these particles in fluorescence microscopy are also demonstrated. In particular, subdiffraction images of nanoparticles were obtained, in the focal plane of a confocal microscope.

Single particle measurements and two particle interferometry results from CERN experiment NA44

International Nuclear Information System (INIS)

Simon-Gillo, J.

1994-01-01

CERN experiment NA44 is optimized for the study of identified single and multiple particle distributions to p T = 0 near mid-rapidity. We measure π +- , K +- , p, bar p, d and bar d, in p + A and A + A collisions at 450 and 20OGeV/u, respectively. Two-particle intensity interferometry results from π + π + , K + K + , and K - K - measurements and single particle distributions are presented

Studies on femtosecond fluorescence dynamics of photosystem II Particle complex at low temperature

CERN Document Server

Liu Xiao; He, Jun Fang; Cai, Xia; Peng Jun Fang; Kuang Ting Yun

2004-01-01

In order to understanding the diversity of energy transfer in PS II at different temperatures, PS II particle complex purified from spinach was investigated with femtosecond time-resolved fluorescence spectroscopy in the case of excitation 507 nm at 83 K, 160 K, 273 K. The data were analyzed by Gauss analysis and fluorescence decay time- fitting. Some results were achieved. (1) Increase of the temperature results in a broadening of the fluorescence emission spectra due to the temperature-dependent expressions for nonradiative transitions between two electronic states. (2) There are at least several characteristic Chl molecules exist in PS II particle complex, i.e. Chl b/sub 639//sup 640/, Chl b/sub 640//sup 645/, Chl a/sub 660//sup 663/, Chl a/sub 667//sup 668/, Chl a/sub 673//sup 676/, Chl a/sub 680 //sup 681/, Chl a/sub 680/681//sup 682/, Chl a/sub 684,685//sup 668 /689/, Chl a/sub 688//sup 698/, (Chl a/b/sub a//sup e/: a represents the peak of absorption, e represents the peak of emission). (3) Though the ...

Probing correlated quantum many-body systems at the single-particle level

Energy Technology Data Exchange (ETDEWEB)

Endres, Manuel

2013-02-27

The detection of correlation and response functions plays a crucial role in the experimental characterization of quantum many-body systems. In this thesis, we present novel techniques for the measurement of such functions at the single-particle level. Specifically, we show the single-atom- and single-site-resolved detection of an ultracold quantum gas in an optical lattice. The quantum gas is described by the Bose-Hubbard model, which features a zero temperature phase transition from a superfluid to a Mott-insulating state, a paradigm example of a quantum phase transition. We used the aforementioned detection techniques to study correlation and response properties across the superfluid-Mott-insulator transition. The single-atom sensitivity of our method is achieved by fluorescence detection of individual atoms with a high signal-to-noise ratio. A high-resolution objective collects the fluorescence light and yields in situ 'snapshots' of the quantum gas that allow for a single-site-resolved reconstruction of the atomic distribution. This allowed us to measure two-site and non-local correlation-functions across the superfluid-Mott-insulator transition. Non-local correlation functions are based on the information of an extended region of the system and play an important role for the characterization of low-dimensional quantum phases. While non-local correlation functions were so far only theoretical tools, our results show that they are actually experimentally accessible. Furthermore, we used a new thermometry scheme, based on the counting of individual thermal excitations, to measure the response of the system to lattice modulation. Using this method, we studied the excitation spectrum of the system across the two-dimensional superfluid-Mott-insulator transition. In particular, we detected a 'Higgs' amplitude mode in the strongly-interacting superfluid close to the transition point where the system is described by an effectively Lorentz

Probing correlated quantum many-body systems at the single-particle level

International Nuclear Information System (INIS)

Endres, Manuel

2013-01-01

The detection of correlation and response functions plays a crucial role in the experimental characterization of quantum many-body systems. In this thesis, we present novel techniques for the measurement of such functions at the single-particle level. Specifically, we show the single-atom- and single-site-resolved detection of an ultracold quantum gas in an optical lattice. The quantum gas is described by the Bose-Hubbard model, which features a zero temperature phase transition from a superfluid to a Mott-insulating state, a paradigm example of a quantum phase transition. We used the aforementioned detection techniques to study correlation and response properties across the superfluid-Mott-insulator transition. The single-atom sensitivity of our method is achieved by fluorescence detection of individual atoms with a high signal-to-noise ratio. A high-resolution objective collects the fluorescence light and yields in situ 'snapshots' of the quantum gas that allow for a single-site-resolved reconstruction of the atomic distribution. This allowed us to measure two-site and non-local correlation-functions across the superfluid-Mott-insulator transition. Non-local correlation functions are based on the information of an extended region of the system and play an important role for the characterization of low-dimensional quantum phases. While non-local correlation functions were so far only theoretical tools, our results show that they are actually experimentally accessible. Furthermore, we used a new thermometry scheme, based on the counting of individual thermal excitations, to measure the response of the system to lattice modulation. Using this method, we studied the excitation spectrum of the system across the two-dimensional superfluid-Mott-insulator transition. In particular, we detected a 'Higgs' amplitude mode in the strongly-interacting superfluid close to the transition point where the system is described by an effectively Lorentz-invariant low-energy theory

Truncated forms of viral VP2 proteins fused to EGFP assemble into fluorescent parvovirus-like particles

Directory of Open Access Journals (Sweden)

Vuento Matti

2006-12-01

Full Text Available Abstract Fluorescence correlation spectroscopy (FCS monitors random movements of fluorescent molecules in solution, giving information about the number and the size of for example nano-particles. The canine parvovirus VP2 structural protein as well as N-terminal deletion mutants of VP2 (-14, -23, and -40 amino acids were fused to the C-terminus of the enhanced green fluorescent protein (EGFP. The proteins were produced in insect cells, purified, and analyzed by western blotting, confocal and electron microscopy as well as FCS. The non-truncated form, EGFP-VP2, diffused with a hydrodynamic radius of 17 nm, whereas the fluorescent mutants truncated by 14, 23 and 40 amino acids showed hydrodynamic radii of 7, 20 and 14 nm, respectively. These results show that the non-truncated EGFP-VP2 fusion protein and the EGFP-VP2 constructs truncated by 23 and by as much as 40 amino acids were able to form virus-like particles (VLPs. The fluorescent VLP, harbouring VP2 truncated by 23 amino acids, showed a somewhat larger hydrodynamic radius compared to the non-truncated EGFP-VP2. In contrast, the construct containing EGFP-VP2 truncated by 14 amino acids was not able to assemble into VLP-resembling structures. Formation of capsid structures was confirmed by confocal and electron microscopy. The number of fluorescent fusion protein molecules present within the different VLPs was determined by FCS. In conclusion, FCS provides a novel strategy to analyze virus assembly and gives valuable structural information for strategic development of parvovirus-like particles.

Fluorescent nanodiamonds as a relevant tag for the assessment of alum adjuvant particle biodisposition.

Science.gov (United States)

Eidi, Housam; David, Marie-Odile; Crépeaux, Guillemette; Henry, Laetitia; Joshi, Vandana; Berger, Marie-Hélène; Sennour, Mohamed; Cadusseau, Josette; Gherardi, Romain K; Curmi, Patrick A

2015-06-17

Aluminum oxyhydroxide (alum) is a crystalline compound widely used as an immunologic adjuvant of vaccines. Concerns linked to alum particles have emerged following recognition of their causative role in the so-called macrophagic myofasciitis (MMF) lesion in patients with myalgic encephalomyelitis, revealing an unexpectedly long-lasting biopersistence of alum within immune cells and a fundamental misconception of its biodisposition. Evidence that aluminum-coated particles phagocytozed in the injected muscle and its draining lymph nodes can disseminate within phagocytes throughout the body and slowly accumulate in the brain further suggested that alum safety should be evaluated in the long term. However, lack of specific staining makes difficult the assessment of low quantities of bona fide alum adjuvant particles in tissues. We explored the feasibility of using fluorescent functionalized nanodiamonds (mfNDs) as a permanent label of alum (Alhydrogel(®)). mfNDs have a specific and perfectly photostable fluorescence based on the presence within the diamond lattice of nitrogen-vacancy centers (NV centers). As the NV center does not bleach, it allows the microspectrometric detection of mfNDs at very low levels and in the long-term. We thus developed fluorescent nanodiamonds functionalized by hyperbranched polyglycerol (mfNDs) allowing good coupling and stability of alum:mfNDs (AluDia) complexes. Specificities of AluDia complexes were comparable to the whole reference vaccine (anti-hepatitis B vaccine) in terms of particle size and zeta potential. In vivo, AluDia injection was followed by prompt phagocytosis and AluDia particles remained easily detectable by the specific signal of the fND particles in the injected muscle, draining lymph nodes, spleen, liver and brain. In vitro, mfNDs had low toxicity on THP-1 cells and AluDia showed cell toxicity similar to alum alone. Expectedly, AluDia elicited autophagy, and allowed highly specific detection of small amounts of alum

Single Molecule Applications of Quantum Dots

DEFF Research Database (Denmark)

Rasmussen, Thomas Elmelund; Jauffred, Liselotte; Brewer, Jonathan R.

2013-01-01

Fluorescent nanocrystals composed of semiconductor materials were first introduced for biological applications in the late 1990s. The focus of this review is to give a brief survey of biological applications of quantum dots (QDs) at the single QD sensitivity level. These are described as follows: 1......) QD blinking and bleaching statistics, 2) the use of QDs in high speed single particle tracking with a special focus on how to design the biofunctional coatings of QDs which enable specific targeting to single proteins or lipids of interest, 3) a hybrid lipid-DNA analogue binding QDs which allows...... for tracking single lipids in lipid bilayers, 4) two-photon fluorescence correlation spectroscopy of QDs and 5) optical trapping and excitation of single QDs. In all of these applications, the focus is on the single particle sensitivity level of QDs. The high applicability of QDs in live cell imaging...

Silicon photon-counting avalanche diodes for single-molecule fluorescence spectroscopy

Science.gov (United States)

Michalet, Xavier; Ingargiola, Antonino; Colyer, Ryan A.; Scalia, Giuseppe; Weiss, Shimon; Maccagnani, Piera; Gulinatti, Angelo; Rech, Ivan; Ghioni, Massimo

2014-01-01

Solution-based single-molecule fluorescence spectroscopy is a powerful experimental tool with applications in cell biology, biochemistry and biophysics. The basic feature of this technique is to excite and collect light from a very small volume and work in a low concentration regime resulting in rare burst-like events corresponding to the transit of a single molecule. Detecting photon bursts is a challenging task: the small number of emitted photons in each burst calls for high detector sensitivity. Bursts are very brief, requiring detectors with fast response time and capable of sustaining high count rates. Finally, many bursts need to be accumulated to achieve proper statistical accuracy, resulting in long measurement time unless parallelization strategies are implemented to speed up data acquisition. In this paper we will show that silicon single-photon avalanche diodes (SPADs) best meet the needs of single-molecule detection. We will review the key SPAD parameters and highlight the issues to be addressed in their design, fabrication and operation. After surveying the state-of-the-art SPAD technologies, we will describe our recent progress towards increasing the throughput of single-molecule fluorescence spectroscopy in solution using parallel arrays of SPADs. The potential of this approach is illustrated with single-molecule Förster resonance energy transfer measurements. PMID:25309114

Optical properties of individual nano-sized gold particle pairs. Mie-scattering, fluorescence, and Raman-scattering

Energy Technology Data Exchange (ETDEWEB)

Olk, Phillip

2008-07-01

This thesis examines and exploits the optical properties of pairs of MNPs. Pairs of MNPs offer two further parameters not existent at single MNPs, which both affect the local optical fields in their vicinity: the distance between them, and their relative orientation with respect to the polarisation of the excitation light. These properties are subject of three chapters: One section examines the distance-dependent and orientation-sensitive scattering cross section (SCS) of two equally sized MNPs. Both near- and far-field interactions affect the spectral position and spectral width of the SCS. Far-field coupling affects the SCS even in such a way that a two-particle system may show both a blue- and redshifted SCS, depending only on the distance between the two MNPs. The maximum distance for this effect is the coherence length of the illumination source - a fact of importance for SCS-based experiments using laser sources. Another part of this thesis examines the near-field between two MNPs and the dependence of the locally enhanced field on the relative particle orientation with respect to the polarisation of the excitation light. To attain a figure of merit, the intensity of fluorescence light from dye molecules in the surrounding medium was measured at various directions of polarisation. The field enhancement was turned into fluorescence enhancement, even providing a means for sensing the presence of very small MNPs of 12 nm in diameter. In order to quantify the near-field experimentally, a different technique is devised in a third section of this thesis - scanning particle-enhanced Raman microscopy (SPRM). This device comprises a scanning probe carrying an MNP which in turn is coated with a molecule of known Raman signature. By manoeuvring this outfit MNP into the vicinity of an illuminated second MNP and by measuring the Raman signal intensity, a spatial mapping of the field enhancement was possible. (orig.)

Apparatus and method for tracking a molecule or particle in three dimensions

Science.gov (United States)

Werner, James H [Los Alamos, NM; Goodwin, Peter M [Los Alamos, NM; Lessard, Guillaume [Santa Fe, NM

2009-03-03

An apparatus and method were used to track the movement of fluorescent particles in three dimensions. Control software was used with the apparatus to implement a tracking algorithm for tracking the motion of the individual particles in glycerol/water mixtures. Monte Carlo simulations suggest that the tracking algorithms in combination with the apparatus may be used for tracking the motion of single fluorescent or fluorescently labeled biomolecules in three dimensions.

Solid-phase single molecule biosensing using dual-color colocalization of fluorescent quantum dot nanoprobes

Science.gov (United States)

Liu, Jianbo; Yang, Xiaohai; Wang, Kemin; Wang, Qing; Liu, Wei; Wang, Dong

2013-10-01

The development of solid-phase surface-based single molecule imaging technology has attracted significant interest during the past decades. Here we demonstrate a sandwich hybridization method for highly sensitive detection of a single thrombin protein at a solid-phase surface based on the use of dual-color colocalization of fluorescent quantum dot (QD) nanoprobes. Green QD560-modified thrombin binding aptamer I (QD560-TBA I) were deposited on a positive poly(l-lysine) assembled layer, followed by bovine serum albumin blocking. It allowed the thrombin protein to mediate the binding of the easily detectable red QD650-modified thrombin binding aptamer II (QD650-TBA II) to the QD560-TBA I substrate. Thus, the presence of the target thrombin can be determined based on fluorescent colocalization measurements of the nanoassemblies, without target amplification or probe separation. The detection limit of this assay reached 0.8 pM. This fluorescent colocalization assay has enabled single molecule recognition in a separation-free detection format, and can serve as a sensitive biosensing platform that greatly suppresses the nonspecific adsorption false-positive signal. This method can be extended to other areas such as multiplexed immunoassay, single cell analysis, and real time biomolecule interaction studies.The development of solid-phase surface-based single molecule imaging technology has attracted significant interest during the past decades. Here we demonstrate a sandwich hybridization method for highly sensitive detection of a single thrombin protein at a solid-phase surface based on the use of dual-color colocalization of fluorescent quantum dot (QD) nanoprobes. Green QD560-modified thrombin binding aptamer I (QD560-TBA I) were deposited on a positive poly(l-lysine) assembled layer, followed by bovine serum albumin blocking. It allowed the thrombin protein to mediate the binding of the easily detectable red QD650-modified thrombin binding aptamer II (QD650-TBA II) to

Spatial and temporal superresolution concepts to study plasma membrane organization by single molecule fluorescence techniques

International Nuclear Information System (INIS)

Ruprecht, V.

2010-01-01

Fluorescence microscopy techniques are currently among the most important experimental tools to study cellular processes. Ultra-sensitive detection devices nowadays allow for measuring even individual farnesylacetate labeled target molecules with nanometer spatial accuracy and millisecond time resolution. The emergence of single molecule fluorescence techniques especially contributed to the field of membrane biology and provided basic knowledge on structural and dynamic features of the cellular plasma membrane. However, we are still confronted with a rather fragmentary understanding of the complex architecture and functional interrelations of membrane constituents. In this thesis new concepts in one- and dual-color single molecule fluorescence techniques are presented that allow for addressing organization principles and interaction dynamics in the live cell plasma membrane. Two complementary experimental strategies are described which differ in their detection principle: single molecule fluorescence imaging and fluorescence correlation spectroscopy. The presented methods are discussed in terms of their implementation, accuracy, quantitative and statistical data analysis, as well as live cell applications. State-of-the-art dual color single molecule imaging is introduced as the most direct experimental approach to study interaction dynamics between differently labeled target molecules. New analytical estimates for robust data analysis are presented that facilitate quantitative recording and identification of co localizations in dual color single molecule images. A novel dual color illumination scheme is further described that profoundly extends the current range and sensitivity of conventional dual color single molecule experiments. The method enables working at high surface densities of fluorescent molecules - a feature typically incommensurable with single molecule imaging - and is especially suited for the detection of rare interactions by tracking co localized

New apparatus of single particle trap system for aerosol visualization

Science.gov (United States)

Higashi, Hidenori; Fujioka, Tomomi; Endo, Tetsuo; Kitayama, Chiho; Seto, Takafumi; Otani, Yoshio

2014-08-01

Control of transport and deposition of charged aerosol particles is important in various manufacturing processes. Aerosol visualization is an effective method to directly observe light scattering signal from laser-irradiated single aerosol particle trapped in a visualization cell. New single particle trap system triggered by light scattering pulse signal was developed in this study. The performance of the device was evaluated experimentally. Experimental setup consisted of an aerosol generator, a differential mobility analyzer (DMA), an optical particle counter (OPC) and the single particle trap system. Polystylene latex standard (PSL) particles (0.5, 1.0 and 2.0 μm) were generated and classified according to the charge by the DMA. Singly charged 0.5 and 1.0 μm particles and doubly charged 2.0 μm particles were used as test particles. The single particle trap system was composed of a light scattering signal detector and a visualization cell. When the particle passed through the detector, trigger signal with a given delay time sent to the solenoid valves upstream and downstream of the visualization cell for trapping the particle in the visualization cell. The motion of particle in the visualization cell was monitored by CCD camera and the gravitational settling velocity and the electrostatic migration velocity were measured from the video image. The aerodynamic diameter obtained from the settling velocity was in good agreement with Stokes diameter calculated from the electrostatic migration velocity for individual particles. It was also found that the aerodynamic diameter obtained from the settling velocity was a one-to-one function of the scattered light intensity of individual particles. The applicability of this system will be discussed.

Detection of {alpha} particles with the aid of a fluorescence counter; Detection des particules {alpha} a l'aide d'un compteur a fluorescence

Energy Technology Data Exchange (ETDEWEB)

Koechlin, Y

1951-07-01

The operation principle of the fluorescence counter, used as {alpha} particles detector, is analyzed in the first part. Detection can be done in two ways: by counting the pulses due to each {alpha} particle, or by integrating all pulses and measuring the average current obtained. In the second part, three series of measurements are presented: 1 - two fluorescent substances (zinc sulfate and anthracene) are placed in front of the photocathode of three types of photomultipliers (RCA 931A, EMI 4588, and EMI 5311). These substances are bombarded with the {alpha} radiations of a Po source and then irradiated by the {beta} and {gamma} radiations of a Ra source in order to study the light emission of these thin film substances when submitted to the three types of radiations. The results show that thanks to the amplitude of the emitted light pulses, the fluorescence counter, when submitted to the three types of radiations, allows to distinguish between the {alpha} radiations of the polonium and the {beta} and {gamma} radiations of the radium source. The output current of a 931A, when measured with a galvanometer, allows to detect Po sources with an intensity of about 10{sup -6} curie. This is observed when its photocathode receives the light from a ZnS-Ag coating bombarded by the {alpha} particles of Po. The quantum efficiency of the counter is close to 100% for the {alpha} particles of Po. This efficiency is evaluated by comparison with the efficiency of a thin wall Geiger-Mueller counter. Moreover, when a thin crystal of anthracene is used as detector, the energy of the incident particles can be measured with a 2% preciseness. (J.S.)

Intracellular formation of α-synuclein oligomers and the effect of heat shock protein 70 characterized by confocal single particle spectroscopy

Energy Technology Data Exchange (ETDEWEB)

Levin, Johannes [Department of Neurology, Ludwig-Maximilians-University, Marchioninistr. 15, 81377 Munich (Germany); German Center for Neurodegenerative Diseases – DZNE, Site Munich, Feodor-Lynen-Str. 17, 81377 Munich (Germany); Hillmer, Andreas S. [Center for Neuropathology and Prion Research, Ludwig-Maximilians-University, Feodor-Lynen-Str. 23, 81377 Munich (Germany); Högen, Tobias [Department of Neurology, Ludwig-Maximilians-University, Marchioninistr. 15, 81377 Munich (Germany); McLean, Pamela J. [Department of Neuroscience, Mayo Clinic, Jacksonville, FL 32224 (United States); Giese, Armin, E-mail: armin.giese@med.uni-muenchen.de [Center for Neuropathology and Prion Research, Ludwig-Maximilians-University, Feodor-Lynen-Str. 23, 81377 Munich (Germany)

2016-08-12

Synucleinopathies such as dementia with Lewy bodies or Parkinson’s disease are characterized by intracellular deposition of pathologically aggregated α-synuclein. The details of the molecular pathogenesis of PD and especially the conditions that lead to intracellular aggregation of α-synuclein and the role of these aggregates in cell death remain unknown. In cell free in vitro systems considerable knowledge about the aggregation processes has been gathered. In comparison, the knowledge about these aggregation processes in cells is far behind. In cells α-synuclein aggregates can be toxic. However, the crucial particle species responsible for decisive steps in pathogenesis such as seeding a continuing aggregation process and triggering cell death remain to be identified. In order to understand the complex nature of intracellular α-synuclein aggregate formation, we analyzed fluorescent particles formed by venus and α-synuclein-venus fusion proteins and α-synuclein-hemi-venus fusion proteins derived from gently lyzed cells. With these techniques we were able to identify and characterize α-synuclein oligomers formed in cells. Especially the use of α-synuclein-hemi-venus fusion proteins enabled us to identify very small α-synuclein oligomers with high sensitivity. Furthermore, we were able to study the molecular effect of heat shock protein 70, which is known to inhibit α-synuclein aggregation in cells. Heat shock protein 70 does not only influence the size of α-synuclein oligomers, but also their quantity. In summary, this approach based on fluorescence single particle spectroscopy, that is suited for high throughput measurements, can be used to detect and characterize intracellularly formed α-synuclein aggregates and characterize the effect of molecules that interfere with α-synuclein aggregate formation. - Highlights: • Single particle spectroscopy detects intracellular formed α-synuclein aggregates. • Fusion proteins allow detection of protein

Platinum plasmonic nanostructure arrays for massively parallel single-molecule detection based on enhanced fluorescence measurements

International Nuclear Information System (INIS)

Saito, Toshiro; Takahashi, Satoshi; Obara, Takayuki; Itabashi, Naoshi; Imai, Kazumichi

2011-01-01

We fabricated platinum bowtie nanostructure arrays producing fluorescence enhancement and evaluated their performance using two-photon photoluminescence and single-molecule fluorescence measurements. A comprehensive selection of suitable materials was explored by electromagnetic simulation and Pt was chosen as the plasmonic material for visible light excitation near 500 nm, which is preferable for multicolor dye-labeling applications like DNA sequencing. The observation of bright photoluminescence (λ = 500-600 nm) from each Pt nanostructure, induced by irradiation at 800 nm with a femtosecond laser pulse, clearly indicates that a highly enhanced local field is created near the Pt nanostructure. The attachment of a single dye molecule was attempted between the Pt triangles of each nanostructure by using selective immobilization chemistry. The fluorescence intensities of the single dye molecule localized on the nanostructures were measured. A highly enhanced fluorescence, which was increased by a factor of 30, was observed. The two-photon photoluminescence intensity and fluorescence intensity showed qualitatively consistent gap size dependence. However, the average fluorescence enhancement factor was rather repressed even in the nanostructure with the smallest gap size compared to the large growth of photoluminescence. The variation of the position of the dye molecule attached to the nanostructure may influence the wide distribution of the fluorescence enhancement factor and cause the rather small average value of the fluorescence enhancement factor.

Single-particle density matrix of liquid 4He

International Nuclear Information System (INIS)

Vakarchuk, I.A.

2008-01-01

The density single-particle matrix in the coordinate notation was calculated based on the expression for the interacting Bose-particle N system density matrix. Under the low temperatures the mentioned matrix in the first approximation enables to reproduce the Bogoliubov theory results. In the classical terms the mentioned theory enables to reproduce the results of the theory of the classical fluids in the approximation of the chaotic phases. On the basis of the density single-particle matrix one managed to obtain the function of the pulse distribution of the particles, the Bose-liquid average kinetic energy, and to study the Bose-Einstein condensation phenomenon [ru

Fractional Hoppinglike Motion in Columnar Mesophases of Semiflexible Rodlike Particles

NARCIS (Netherlands)

Naderi, S.; Pouget, E.; Ballesta, P.; van der Schoot, P. P. A. M.; Lettinga, M.P.; Grelet, E

2013-01-01

We report on single-particle dynamics of strongly interacting filamentous fd virus particles in the liquid-crystalline columnar state in aqueous solution. From fluorescence microscopy, we find that rare, discrete events take place, in which individual particles engage in sudden, jumplike motion

Single particle tracking and single molecule energy transfer

CERN Document Server

Bräuchle, Christoph; Michaelis, Jens

2009-01-01

Closing a gap in the literature, this handbook gathers all the information on single particle tracking and single molecule energy transfer. It covers all aspects of this hot and modern topic, from detecting virus entry to membrane diffusion, and from protein folding using spFRET to coupled dye systems, as well recent achievements in the field. Throughout, the first-class editors and top international authors present content of the highest quality, making this a must-have for physical chemists, spectroscopists, molecular physicists and biochemists.

Development of real time detector for fluorescent particles applied to pollutant transfers characterization

International Nuclear Information System (INIS)

Prevost, C.

1996-06-01

The studies on aerosol transfer carried out in the field of staff protection and nuclear plants safety become more and more important. So techniques of pollutants simulation by specific tracers with the same aeraulic behaviour are an interesting tool in order to characterize their transfers. Resorting to aerosols tagged by a fluorescent dye allows to realize different studies in ventilation and filtration field. The feasibility of detection in real time for a particulate tracer is the main aim of this work. The need of such a technique is obvious because it can provide the specific aerosol behaviour. Furthermore, direct measurements in real time are required for model validation in calculation codes: they give the most realistic informations on interaction between contaminant and ventilation air flows. Up to now, the principle of fluorescent aerosol concentration measurement allows only an integral response in a delayed time, by means of sampling on filters and a fluorimetric analysis after a specific conditioning of these filters. In order to have the opportunity to detect in real time specific tracer, we have developed a new monitor able to count these particles on the following basis: fluorescent particles pass through a sampling nozzle up to a measurement chamber specially designed; sheath flow rate is defined to confine the test aerosol in the test aerosol in the sample flow rate at nozzle outlet; the interception of this stream by a highly focused laser beam allows aerosol detection and characterization particle by particle; the signature of a passing aerosol is the burst of photons that occurs when the fluoro-phore contained in the glycerol particle is excited by a light of adapted wavelength; these signals are transmitted to a photodetector by a patented optical arrangement. Then, an acquisition interfaced board connected to a computer, converts them into frequencies histograms. In the end, two kind of results could be provided simultaneously : the

Velocity of a single gas plug rising through a particle-gas-liquid three-phase flow (In the case that particles updrift in a stagnant liquid column)

International Nuclear Information System (INIS)

Koizumi, Yasuo; Shimada, Jun; Ohtake, Hiroyasu

1999-01-01

The velocity of a single air plug rising through a stagnant water column in a pipe with updrifting particles has been examined at atmospheric pressure and room temperature. The particles used were polymer balls with a diameter of 3.18 mm and a density of 0.835 x 10 -3 kg/m 3 . The water velocity in a film around the plug and a wake region behind the plug was measured by a laser Doppler velocimeter. The thickness of the film was also measured with a dye-fluoresce-method by a laser ray. When the updrifting particles were introduced, the rising velocity of the plug became fast a little. However, the velocity was considerably slower than that in the falling particle case and independent on the particle introduction rate. The film around the plug was thicker a little than that in the no particle case, however considerably thinner than that in the falling particle case. The water velocity in the film around the plug was slower a little than that in the no particle case, and not dependent on the particle introduction rate contrary to that in the falling particle case. The vortex size behind the plug was almost the same as that in the no particle case although the vortex region was spread downward in the falling particle case. (author)

Size distributions and temporal variations of biological aerosol particles in the Amazon rainforest characterized by microscopy and real-time UV-APS fluorescence techniques during AMAZE-08

Directory of Open Access Journals (Sweden)

J. A. Huffman

2012-12-01

Full Text Available As a part of the AMAZE-08 campaign during the wet season in the rainforest of central Amazonia, an ultraviolet aerodynamic particle sizer (UV-APS was operated for continuous measurements of fluorescent biological aerosol particles (FBAP. In the coarse particle size range (> 1 μm the campaign median and quartiles of FBAP number and mass concentration were 7.3 × 10⁴ m⁻³ (4.0–13.2 × 10⁴ m⁻³ and 0.72 μg m⁻³ (0.42–1.19 μg m⁻³, respectively, accounting for 24% (11–41% of total particle number and 47% (25–65% of total particle mass. During the five-week campaign in February–March 2008 the concentration of coarse-mode Saharan dust particles was highly variable. In contrast, FBAP concentrations remained fairly constant over the course of weeks and had a consistent daily pattern, peaking several hours before sunrise, suggesting observed FBAP was dominated by nocturnal spore emission. This conclusion was supported by the consistent FBAP number size distribution peaking at 2.3 μm, also attributed to fungal spores and mixed biological particles by scanning electron microscopy (SEM, light microscopy and biochemical staining. A second primary biological aerosol particle (PBAP mode between 0.5 and 1.0 μm was also observed by SEM, but exhibited little fluorescence and no true fungal staining. This mode may have consisted of single bacterial cells, brochosomes, various fragments of biological material, and small Chromalveolata (Chromista spores. Particles liquid-coated with mixed organic-inorganic material constituted a large fraction of observations, and these coatings contained salts likely from primary biological origin. We provide key support for the suggestion that real-time laser-induce fluorescence (LIF techniques using 355 nm excitation provide size-resolved concentrations of FBAP as a lower limit for the atmospheric abundance of biological particles in a pristine

Automated data collection in single particle electron microscopy

Science.gov (United States)

Tan, Yong Zi; Cheng, Anchi; Potter, Clinton S.; Carragher, Bridget

2016-01-01

Automated data collection is an integral part of modern workflows in single particle electron microscopy (EM) research. This review surveys the software packages available for automated single particle EM data collection. The degree of automation at each stage of data collection is evaluated, and the capabilities of the software packages are described. Finally, future trends in automation are discussed. PMID:26671944

Single particle irradiation effect of digital signal processor

International Nuclear Information System (INIS)

Fan Si'an; Chen Kenan

2010-01-01

The single particle irradiation effect of high energy neutron on digital signal processor TMS320P25 in dynamic working condition has been studied. The influence of the single particle on the device has been explored through the acquired waveform and working current of TMS320P25. Analysis results, test data and test methods have also been presented. (authors)

A simple optical fiber device for quantitative fluorescence microscopy of single living cells

OpenAIRE

van Graft, M.; van Graft, Marja; Oosterhuis, B.; Oosterhuis, Bernard; van der Werf, Kees; de Grooth, B.G.; Greve, Jan

1993-01-01

simple and relatively inexpensive system is described for obtaining quantitative fluorescence measurements on single living cells loaded with a fluorescent probe to study cell physiological processes. The light emitted from the fluorescent cells is captured by and transported through an optical fiber. After passage through appropriate filters the light is measured using a photomultiplier tube. The optical fiber is mounted in one of the microscope outlets. Signals derived from the photomultipl...

Controlled Synthesis and Fluorescence Tracking of Highly Uniform Poly(N-isopropylacrylamide) Microgels.

Science.gov (United States)

Virtanen, Otto L J; Purohit, Ashvini; Brugnoni, Monia; Wöll, Dominik; Richtering, Walter

2016-09-08

Stimuli-sensitive poly(N-isopropylacrylamide) (PNIPAM) microgels have various prospective practical applications and uses in fundamental research. In this work, we use single particle tracking of fluorescently labeled PNIPAM microgels as a showcase for tuning microgel size by a rapid non-stirred precipitation polymerization procedure. This approach is well suited for prototyping new reaction compositions and conditions or for applications that do not require large amounts of product. Microgel synthesis, particle size and structure determination by dynamic and static light scattering are detailed in the protocol. It is shown that the addition of functional comonomers can have a large influence on the particle nucleation and structure. Single particle tracking by wide-field fluorescence microscopy allows for an investigation of the diffusion of labeled tracer microgels in a concentrated matrix of non-labeled microgels, a system not easily investigated by other methods such as dynamic light scattering.

ANTS-anchored Zn-Al-CO3-LDH particles as fluorescent probe for sensing of folic acid

International Nuclear Information System (INIS)

Liu, Pengfei; Liu, Dan; Liu, Yanhuan; Li, Lei

2016-01-01

A novel fluorescent nanosensor for detecting folic acid (FA) in aqueous media has been developed based on 8-aminonaphthalene-1,3,6-trisulfonate (ANTS) anchored to the surface of Zn-Al-CO 3 -layered double hydroxides (LDH) particles. The nanosensor showed high fluorescence intensity and good photostability due to a strong coordination interaction between surface Zn 2+ ions of Zn-Al-CO 3 -LDH and N atoms of ANTS, which were verified by result of X-ray photoelectron spectroscopy (XPS). ANTS-anchored on the surface of Zn-Al-CO 3 -LDH restricted the intra-molecular rotation leading to ANTS-anchored J-type aggregation emission enhancement. ANTS-anchored Zn-Al-CO 3 -LDH particles exhibited highly sensitive and selective response to FA over other common metal ions and saccharides present in biological fluids. The proposed mechanism was that oxygen atoms of -SO 3 groups in ANTS-anchored on the surface of Zn-Al-CO 3 -LDH were easily collided by FA molecules to form potential hydrogen bonds between ANTS-anchored and FA molecules, which could effectively quench the ANTS-anchored fluorescence. Under the simulated physiological conditions (pH of 7.4), the fluorescence quenching was fitted to Stern-Volmer equation with a linear response in the concentration range of 1 μM to 200 μM with a limit of detection of 0.1 μM. The results indicate that ANTS-anchored Zn-Al-CO 3 -LDH particles can afford a very sensitive system for the sensing FA in aqueous solution. - Highlights: • A novel fluorescent nanosensor has been developed. • The sensor exhibited highly sensitive and selective response to FA. • The fluorescence quenching was fitted to Stern–Volmer equation. • The linear response range was 1–200 μM with a limit of detection of 0.1 μM.

Retarded Local Dynamics of Single Fluorescent Probes in Polymeric Glass due to Interaction Strengthening

Science.gov (United States)

Zhang, Hao; Yang, Jingfa; Zhao, Jiang

The effect of strengthening of interaction between single fluorescent probes and polymer matrix to the probes dynamics is investigated using single molecule fluorescence defocus microscopy. By introducing multiple hydroxyl groups to the fluorescent probes, which builds up hydrogen bonds between the probe and polymer matrix, the dynamics is discovered to be retarded. This is evidenced by the lowering of the frequency of the vibrational modes in the power spectra of the rotation trajectories of individual fluorescent probes, and also by the lowering of population of rotating probes. The results show that by strengthening the probe-matrix interaction, the local dynamics detected by the probes is equivalent to that detected by a bigger probe, due to the enhanced friction between the probe and the polymer matrix. the National Basic Research Program of China (2012CB821500).

Fluorescent metal nanoshell and CK19 detection on single cell image

International Nuclear Information System (INIS)

Zhang, Jian; Fu, Yi; Li, Ge; Lakowicz, Joseph R.; Zhao, Richard Y.

2011-01-01

Highlights: → Novel metal nanoshell as fluorescence imaging agent. → Fluorescent mAb-metal complex with enhanced intensity and shortened lifetime. → Immuno-interactions of mAb-metal complexes with CK19 molecules on CNCAP and HeLa cell surfaces. → Isolation of conjugated mAb-metal complexes from cellular autofluorescence on cell image. -- Abstract: In this article, we report the synthesis strategy and optical properties of a novel type of fluorescence metal nanoshell when it was used as imaging agent for fluorescence cell imaging. The metal nanoshells were made with 40 nm silica cores and 10 nm silver shells. Unlike typical fluorescence metal nanoshells which contain the organic dyes in the cores, novel metal nanoshells were composed of Cy5-labelled monoclonal anti-CK19 antibodies (mAbs) on the external surfaces of shells. Optical measurements to the single nanoparticles showed that in comparison with the metal free labelled mAbs, the mAb-Ag complexes displayed significantly enhanced emission intensity and dramatically shortened lifetime due to near-field interactions of fluorophores with metal. These metal nanoshells were found to be able to immunoreact with target cytokeratin 19 (CK19) molecules on the surfaces of LNCAP and HeLa cells. Fluorescence cell images were recorded on a time-resolved confocal microscope. The emissions from the metal nanoprobes could be clearly isolated from the cellular autofluorescence backgrounds on the cell images as either individuals or small clusters due to their stronger emission intensities and shorter lifetimes. These emission signals could also be precisely counted on single cell images. The count number may provide an approach for quantifying the target molecules in the cells.

Single-particle states vs. collective modes: friends or enemies ?

Science.gov (United States)

Otsuka, T.; Tsunoda, Y.; Togashi, T.; Shimizu, N.; Abe, T.

2018-05-01

The quantum self-organization is introduced as one of the major underlying mechanisms of the quantum many-body systems. In the case of atomic nuclei as an example, two types of the motion of nucleons, single-particle states and collective modes, dominate the structure of the nucleus. The collective mode arises as the balance between the effect of the mode-driving force (e.g., quadrupole force for the ellipsoidal deformation) and the resistance power against it. The single-particle energies are one of the sources to produce such resistance power: a coherent collective motion is more hindered by larger spacings between relevant single particle states. Thus, the single-particle state and the collective mode are "enemies" against each other. However, the nuclear forces are rich enough so as to enhance relevant collective mode by reducing the resistance power by changing single-particle energies for each eigenstate through monopole interactions. This will be verified with the concrete example taken from Zr isotopes. Thus, the quantum self-organization occurs: single-particle energies can be self-organized by (i) two quantum liquids, e.g., protons and neutrons, (ii) monopole interaction (to control resistance). In other words, atomic nuclei are not necessarily like simple rigid vases containing almost free nucleons, in contrast to the naïve Fermi liquid picture. Type II shell evolution is considered to be a simple visible case involving excitations across a (sub)magic gap. The quantum self-organization becomes more important in heavier nuclei where the number of active orbits and the number of active nucleons are larger.

Note: Time-gated 3D single quantum dot tracking with simultaneous spinning disk imaging

International Nuclear Information System (INIS)

DeVore, M. S.; Stich, D. G.; Keller, A. M.; Phipps, M. E.; Hollingsworth, J. A.; Goodwin, P. M.; Werner, J. H.; Cleyrat, C.; Lidke, D. S.; Wilson, B. S.

2015-01-01

We describe recent upgrades to a 3D tracking microscope to include simultaneous Nipkow spinning disk imaging and time-gated single-particle tracking (SPT). Simultaneous 3D molecular tracking and spinning disk imaging enable the visualization of cellular structures and proteins around a given fluorescently labeled target molecule. The addition of photon time-gating to the SPT hardware improves signal to noise by discriminating against Raman scattering and short-lived fluorescence. In contrast to camera-based SPT, single-photon arrival times are recorded, enabling time-resolved spectroscopy (e.g., measurement of fluorescence lifetimes and photon correlations) to be performed during single molecule/particle tracking experiments

Note: Time-gated 3D single quantum dot tracking with simultaneous spinning disk imaging

Energy Technology Data Exchange (ETDEWEB)

DeVore, M. S.; Stich, D. G.; Keller, A. M.; Phipps, M. E.; Hollingsworth, J. A.; Goodwin, P. M.; Werner, J. H., E-mail: jwerner@lanl.gov [Center for Integrated Nanotechnologies, Los Alamos National Laboratory, Mail Stop G755, Los Alamos, New Mexico 87545 (United States); Cleyrat, C.; Lidke, D. S.; Wilson, B. S. [Department of Pathology and Cancer Research and Treatment Center, University of New Mexico, Albuquerque, New Mexico 87131 (United States)

2015-12-15

We describe recent upgrades to a 3D tracking microscope to include simultaneous Nipkow spinning disk imaging and time-gated single-particle tracking (SPT). Simultaneous 3D molecular tracking and spinning disk imaging enable the visualization of cellular structures and proteins around a given fluorescently labeled target molecule. The addition of photon time-gating to the SPT hardware improves signal to noise by discriminating against Raman scattering and short-lived fluorescence. In contrast to camera-based SPT, single-photon arrival times are recorded, enabling time-resolved spectroscopy (e.g., measurement of fluorescence lifetimes and photon correlations) to be performed during single molecule/particle tracking experiments.

Fluorescence detection of single molecules using pulsed near-field optical excitation and time correlated photon counting

International Nuclear Information System (INIS)

Ambrose, W.P.; Goodwin, P.M.; Martin, J.C.; Keller, R.A.

1994-01-01

Pulsed excitation, time correlated single photon counting and time gated detection are used in near-field optical microscopy to enhance fluorescence images and measure the fluorescence lifetimes of single molecules of Rhodamine 6G on silica surfaces. Time gated detection is used to reject prompt scattered background and to improve the image signal to noise ratio. The excited state lifetime of a single Rhodamine 6G molecule is found to depend on the position of the near-field probe. We attribute the lifetime variations to spontaneous emission rate alterations by the fluorescence reflected from and quenching by the aluminum coated probe

Quantum measurement and orientation tracking of fluorescent nanodiamonds inside living cells

Science.gov (United States)

McGuinness, L. P.; Yan, Y.; Stacey, A.; Simpson, D. A.; Hall, L. T.; MacLaurin, D.; Prawer, S.; Mulvaney, P.; Wrachtrup, J.; Caruso, F.; Scholten, R. E.; Hollenberg, L. C. L.

2011-06-01

Fluorescent particles are routinely used to probe biological processes. The quantum properties of single spins within fluorescent particles have been explored in the field of nanoscale magnetometry, but not yet in biological environments. Here, we demonstrate optically detected magnetic resonance of individual fluorescent nanodiamond nitrogen-vacancy centres inside living human HeLa cells, and measure their location, orientation, spin levels and spin coherence times with nanoscale precision. Quantum coherence was measured through Rabi and spin-echo sequences over long (>10 h) periods, and orientation was tracked with effective 1° angular precision over acquisition times of 89 ms. The quantum spin levels served as fingerprints, allowing individual centres with identical fluorescence to be identified and tracked simultaneously. Furthermore, monitoring decoherence rates in response to changes in the local environment may provide new information about intracellular processes. The experiments reported here demonstrate the viability of controlled single spin probes for nanomagnetometry in biological systems, opening up a host of new possibilities for quantum-based imaging in the life sciences.

Fluorescence spectroscopy of conformational changes of single LH2 complexes

NARCIS (Netherlands)

Rutkauskas, D.; Novoderezhkin, V.; Cogdell, R.J.; van Grondelle, R.

2005-01-01

We have investigated the energy landscape of the bacterial photosynthetic peripheral light-harvesting complex LH2 of purple bacterium Rhodopseudomonas acidophila by monitoring sequences of fluorescence spectra of single LH2 assemblies, at room temperature, with different excitation intensities as

Laser excited fluorescence spectrum of Ho3+:SrF2 single crystal

International Nuclear Information System (INIS)

Lal, Bansi; Ramachandra Rao, D.

1980-01-01

The fluorescence spectrum of Ho 3+ : SrF 2 single crystal excited by the various lines of an Ar + laser, is reported. The three fluorescence groups recorded in the region 5300-7700 A, correspond to the transitions from ( 5 F 4 , 5 S 2 ) to 5 I 8 , 5 F 5 to 5 I 8 , 5 F 3 to 5 I 7 and ( 5 F 4 , 5 S 2 ) to 5 I 7 . Marked changes in the total integrated intensity of the various fluorescence groups with the change in the exciting wavelength are observed. (author)

Dual color single particle tracking via nanobodies

International Nuclear Information System (INIS)

Albrecht, David; Winterflood, Christian M; Ewers, Helge

2015-01-01

Single particle tracking is a powerful tool to investigate the function of biological molecules by following their motion in space. However, the simultaneous tracking of two different species of molecules is still difficult to realize without compromising the length or density of trajectories, the localization accuracy or the simplicity of the assay. Here, we demonstrate a simple dual color single particle tracking assay using small, bright, high-affinity labeling via nanobodies of accessible targets with widely available instrumentation. We furthermore apply a ratiometric step-size analysis method to visualize differences in apparent membrane viscosity. (paper)

Development of a high throughput single-particle screening for inorganic semiconductor nanorods as neural voltage sensor

Science.gov (United States)

Kuo, Yung; Park, Kyoungwon; Li, Jack; Ingargiola, Antonino; Park, Joonhyuck; Shvadchak, Volodymyr; Weiss, Shimon

2017-08-01

Monitoring membrane potential in neurons requires sensors with minimal invasiveness, high spatial and temporal (sub-ms) resolution, and large sensitivity for enabling detection of sub-threshold activities. While organic dyes and fluorescent proteins have been developed to possess voltage-sensing properties, photobleaching, cytotoxicity, low sensitivity, and low spatial resolution have obstructed further studies. Semiconductor nanoparticles (NPs), as prospective voltage sensors, have shown excellent sensitivity based on Quantum confined Stark effect (QCSE) at room temperature and at single particle level. Both theory and experiment have shown their voltage sensitivity can be increased significantly via material, bandgap, and structural engineering. Based on theoretical calculations, we synthesized one of the optimal candidates for voltage sensors: 12 nm type-II ZnSe/CdS nanorods (NRs), with an asymmetrically located seed. The voltage sensitivity and spectral shift were characterized in vitro using spectrally-resolved microscopy using electrodes grown by thin film deposition, which "sandwich" the NRs. We characterized multiple batches of such NRs and iteratively modified the synthesis to achieve higher voltage sensitivity (ΔF/F> 10%), larger spectral shift (>5 nm), better homogeneity, and better colloidal stability. Using a high throughput screening method, we were able to compare the voltage sensitivity of our NRs with commercial spherical quantum dots (QDs) with single particle statistics. Our method of high throughput screening with spectrally-resolved microscope also provides a versatile tool for studying single particles spectroscopy under field modulation.

Review: The Use of Real-Time Fluorescence Instrumentation to Monitor Ambient Primary Biological Aerosol Particles (PBAP

Directory of Open Access Journals (Sweden)

Mehael J. Fennelly

2017-12-01

Full Text Available Primary biological aerosol particles (PBAP encompass many particle types that are derived from several biological kingdoms. These aerosol particles can be composed of both whole living units such as pollen, bacteria, and fungi, as well as from mechanically formed particles, such as plant debris. They constitute a significant proportion of the overall atmospheric particle load and have been linked with adverse health issues and climatic effects on the environment. Traditional methods for their analysis have focused on the direct capture of PBAP before subsequent laboratory analysis. These analysis types have generally relied on direct optical microscopy or incubation on agar plates, followed by time-consuming microbiological investigation. In an effort to address some of these deficits, real-time fluorescence monitors have come to prominence in the analysis of PBAP. These instruments offer significant advantages over traditional methods, including the measurement of concentrations, as well as the potential to simultaneously identify individual analyte particles in real-time. Due to the automated nature of these measurements, large data sets can be collected and analyzed with relative ease. This review seeks to highlight and discuss the extensive literature pertaining to the most commonly used commercially available real-time fluorescence monitors (WIBS, UV-APS and BioScout. It discusses the instruments operating principles, their limitations and advantages, and the various environments in which they have been deployed. The review provides a detailed examination of the ambient fluorescent aerosol particle concentration profiles that are obtained by these studies, along with the various strategies adopted by researchers to analyze the substantial data sets the instruments generate. Finally, a brief reflection is presented on the role that future instrumentation may provide in revolutionizing this area of atmospheric research.

Stratospheric particles: Synchrotron x-ray fluorescence determination of trace element contents

International Nuclear Information System (INIS)

Sutton, S.R.; Flynn, G.J.

1987-01-01

The first trace element analyses on stratospheric particles using synchrotron x-ray fluorescence (SXRF) are reported. Cr, Mn, Fe, Ni, Cu, Zn, Ga, Ge, Se and Br were detected. Concentrations for chondritic particle U2022G1 are within a factor of 1.7 of CI for all elements detected with the exception of Br which is 37 times CI. Chondritic particle W7029*A27 is also near CI for Cr, Mn, Fe, Ni, Cu, Zn and Ge but enriched in Ga, Se, and Br by factors of 5.8, 3.5 and 8.4, respectively. The third particle of the cosmic dust class also showed high Br enriched relative to CI by a factor of 28. Br was also detected at a high level in an aluminum-rich particle classified as probable artificial terrestrial contamination but exhibiting a chondritic Fe/Ni ratio. Br was not detected in a fifth particle also classified terrestrial and exhibiting a crustal Fe/Ni ratio. If the high Br has a pre-terrestrial origin, the ubiquity of the effect suggests that a large fraction of the chondritic interplanetary dust particles derive from a parent body (bodies) not sampled in the meteorite collection. 26 refs., 3 figs., 3 tabs

Study on the fragmentation of granite due to the impact of single particle and double particles

Directory of Open Access Journals (Sweden)

Yuchun Kuang

2016-09-01

Full Text Available Particle Impact Drilling (PID is a novel method to improve the rate of penetration (ROP. In order to further improve the performance of PID, an investigation into the effect of single and double particles: (1 diameter; (2 initial velocity; (3 distance; and (4 angle of incidence was undertaken to investigate their effects on broken volume and penetration depth into hard brittle rock. For this purpose, the laboratory experiment of single particle impact rock was employed. Meanwhile, based on the LS-DYNA, a new finite element (FE simulation of the PID, including single and double particles impact rock, has been presented. The 3-dimensional (3D, aix-symmetric, dynamic-explicit, Lagrangian model has been considered in this simulation. And the Elastic and Holmquist Johnson Cook (HJC material behaviors have been used for particles and rocks, respectively. The FE simulation results of single particle impacting rock are good agreement with experimental data. Furthermore, in this article the optimal impact parameters, including diameter, initial velocity, distance and the angle of incidence, are obtained in PID.

Single track coincidence measurements of fluorescent and plastic nuclear track detectors in therapeutic carbon beams

International Nuclear Information System (INIS)

Osinga, J-M; Jäkel, O; Ambrožová, I; Brabcová, K Pachnerová; Davídková, M; Akselrod, M S; Greilich, S

2014-01-01

In this paper we present a method for single track coincidence measurements using two different track detector materials. We employed plastic and fluorescent nuclear track detectors (PNTDs and FNTDs) in the entrance channel of a monoenergetic carbon ion beam covering the therapeutic energy range from 80 to 425 MeV/u. About 99% of all primary particle tracks detected by both detectors were successfully matched, while 1% of the particles were only detected by the FNTDs because of their superior spatial resolution. We conclude that both PNTDs and FNTDs are suitable for clinical carbon beam dosimetry with a detection efficiency of at least 98.82% and 99.83% respectively, if irradiations are performed with low fluence in the entrance channel of the ion beam. The investigated method can be adapted to other nuclear track detectors and offers the possibility to characterize new track detector materials against well-known detectors. Further, by combining two detectors with a restricted working range in the presented way a hybrid-detector system can be created with an extended and optimized working range

Irradiation of single cells with individual high-LET particles

International Nuclear Information System (INIS)

Nelson, J.M.; Braby, L.A.

1993-01-01

The dose-limiting normal tissue of concern when irradiating head and neck lesions is often the vascular endothelium within the treatment field. Consequently, the response of capillary endothelial cells exposed to moderate doses of high LET particles is essential for establishing exposure limits for neutron-capture therapy. In an effort to characterize the high-LET radiation biology of cultured endothelial cells, the authors are attempting to measure cellular response to single particles. The single-particle irradiation apparatus, described below, allows them to expose individual cells to known numbers of high-LET particles and follow these cells for extended periods, in order to assess the impact of individual particles on cell growth kinetics. Preliminary cell irradiation experiments have revealed complications related to the smooth and efficient operation of the equipment; these are being resolved. Therefore, the following paragraphs deal primarily with the manner by which high LET particles deposit energy, the requirements for single-cell irradiation, construction and assembly of such apparatus, and testing of experimental procedures, rather than with the radiation biology of endothelial cells

Image segmentation and dynamic lineage analysis in single-cell fluorescence microscopy.

Science.gov (United States)

Wang, Quanli; Niemi, Jarad; Tan, Chee-Meng; You, Lingchong; West, Mike

2010-01-01

An increasingly common component of studies in synthetic and systems biology is analysis of dynamics of gene expression at the single-cell level, a context that is heavily dependent on the use of time-lapse movies. Extracting quantitative data on the single-cell temporal dynamics from such movies remains a major challenge. Here, we describe novel methods for automating key steps in the analysis of single-cell, fluorescent images-segmentation and lineage reconstruction-to recognize and track individual cells over time. The automated analysis iteratively combines a set of extended morphological methods for segmentation, and uses a neighborhood-based scoring method for frame-to-frame lineage linking. Our studies with bacteria, budding yeast and human cells, demonstrate the portability and usability of these methods, whether using phase, bright field or fluorescent images. These examples also demonstrate the utility of our integrated approach in facilitating analyses of engineered and natural cellular networks in diverse settings. The automated methods are implemented in freely available, open-source software.

Fluorescent nanodiamonds embedded in biocompatible translucent shells.

Science.gov (United States)

Rehor, Ivan; Slegerova, Jitka; Kucka, Jan; Proks, Vladimir; Petrakova, Vladimira; Adam, Marie-Pierre; Treussart, François; Turner, Stuart; Bals, Sara; Sacha, Pavel; Ledvina, Miroslav; Wen, Amy M; Steinmetz, Nicole F; Cigler, Petr

2014-03-26

High pressure high temperature (HPHT) nanodiamonds (NDs) represent extremely promising materials for construction of fluorescent nanoprobes and nanosensors. However, some properties of bare NDs limit their direct use in these applications: they precipitate in biological solutions, only a limited set of bio-orthogonal conjugation techniques is available and the accessible material is greatly polydisperse in shape. In this work, we encapsulate bright 30-nm fluorescent nanodiamonds (FNDs) in 10-20-nm thick translucent (i.e., not altering FND fluorescence) silica shells, yielding monodisperse near-spherical particles of mean diameter 66 nm. High yield modification of the shells with PEG chains stabilizes the particles in ionic solutions, making them applicable in biological environments. We further modify the opposite ends of PEG chains with fluorescent dyes or vectoring peptide using click chemistry. High conversion of this bio-orthogonal coupling yielded circa 2000 dye or peptide molecules on a single FND. We demonstrate the superior properties of these particles by in vitro interaction with human prostate cancer cells: while bare nanodiamonds strongly aggregate in the buffer and adsorb onto the cell membrane, the shell encapsulated NDs do not adsorb nonspecifically and they penetrate inside the cells. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Single-Photon Source for Quantum Information Based on Single Dye Molecule Fluorescence in Liquid Crystal Host

International Nuclear Information System (INIS)

Lukishova, S.G.; Knox, R.P.; Freivald, P.; McNamara, A.; Boyd, R.W.; Stroud, Jr. C.R.; Schmid, A.W.; Marshall, K.L.

2006-01-01

This paper describes a new application for liquid crystals: quantum information technology. A deterministically polarized single-photon source that efficiently produces photons exhibiting antibunching is a pivotal hardware element in absolutely secure quantum communication. Planar-aligned nematic liquid crystal hosts deterministically align the single dye molecules which produce deterministically polarized single (antibunched) photons. In addition, 1-D photonic bandgap cholesteric liquid crystals will increase single-photon source efficiency. The experiments and challenges in the observation of deterministically polarized fluorescence from single dye molecules in planar-aligned glassy nematic-liquid-crystal oligomer as well as photon antibunching in glassy cholesteric oligomer are described for the first time

Considerations of particle vaporization and analyte diffusion in single-particle inductively coupled plasma-mass spectrometry

International Nuclear Information System (INIS)

Ho, Koon-Sing; Lui, Kwok-On; Lee, Kin-Ho; Chan, Wing-Tat

2013-01-01

The intensity of individual gold nanoparticles with nominal diameters of 80, 100, 150, and 200 nm was measured using single-particle inductively coupled plasma-mass spectrometry (ICP-MS). Since the particles are not perfectly monodisperse, a distribution of ICP-MS intensity was obtained for each nominal diameter. The distribution of particle mass was determined from the transmission electron microscopy (TEM) image of the particles. The distribution of ICP-MS intensity and the distribution of particle mass for each nominal diameter were correlated to give a calibration curve. The calibration curves are linear, but the slope decreases as the nominal diameter increases. The reduced slope is probably due to a smaller degree of vaporization of the large particles. In addition to the degree of particle vaporization, the rate of analyte diffusion in the ICP is an important factor that determines the measured ICP-MS intensity. Simulated ICP-MS intensity versus particle size was calculated using a simple computer program that accounts for the vaporization rate of the gold nanoparticles and the diffusion rate and degree of ionization of the gold atoms. The curvature of the simulated calibration curves changes with sampling depth because the effects of particle vaporization and analyte diffusion on the ICP-MS intensity are dependent on the residence time of the particle in the ICP. Calibration curves of four hypothetical particles representing the four combinations of high and low boiling points (2000 and 4000 K) and high and low analyte diffusion rates (atomic masses of 10 and 200 Da) were calculated to further illustrate the relative effects of particle vaporization and analyte diffusion. The simulated calibration curves show that the sensitivity of single-particle ICP-MS is smaller than that of the ICP-MS measurement of continuous flow of standard solutions by a factor of 2 or more. Calibration using continuous flow of standard solution is semi-quantitative at best. An

Fluorescence spectra of bithiophene and terthiophene single crystals and of their isolated molecules in cyclodextrin

International Nuclear Information System (INIS)

Gombojav, Bold; Namsrai, Nasanbat; Yoshinari, Takehisa; Nagasaka, Shin-ichiro; Itoh, Hiroki; Koyama, Kiyohito

2004-01-01

In order to examine the effect of subsumption space of β- and γ-cyclodextrin (CyD) on the photophysics of oligothiophenes, 2, 2'-bithiophene (BT) and 2, 2': 5', 2''-terthiophene (TT), the fluorescence spectra were compared with those of the single crystals (SC) at 15, 77 K and room temperature (RT). Both the numbers of BT included in β- and γ-CyD are twin (BT 2 ). The numbers of TT included in β- and γ-CyD are unit (TT 1 ) and twin (TT 2 ), respectively. Electronic excitation of BT encapsulated in β- and γ-CyD gives similar fluorescence spectra, showing bathochromic shift compared with that of BT single crystal, (BT) SC . The observation that the fluorescence spectra of encapsulated BT 2 are similar to the spectra of its THF solution suggests the configuration of BT 2 in β- and γ-CyD should be face-to-face configuration (BT 2 ) parrallel . On the contrary, TT in β- and in γ-CyD afford quite different fluorescence spectra. Encapsulated TT in β-CyD exhibits the hypsochromic shift of fluorescence maxima compared to that of TT single crystal, (TT) SC . While the bathochromically shifted fluorescence spectra of TT 2 in γ-CyD is also ascribed to the face-to-face configuration (TT 2 ) parallel as in the case of BT 2 in γ-CyD. Fluorescence spectra show the excited ground state complex of BT 2 and TT 2 in γ-CyD

Report of the working group on single-particle nonlinear dynamics

International Nuclear Information System (INIS)

Bazzani, A.; Bongini, L.; Corbett, J.; Dome, G.; Fedorova, A.; Freguglia, P.; Ng, K.; Ohmi, K.; Owen, H.; Papaphilippou, Y.; Robin, D.; Safranek, J.; Scandale, W.; Terebilo, A.; Turchetti, G.; Todesco, E.; Warnock, R.; Zeitlin, M.

1999-01-01

The Working Group on single-particle nonlinear dynamics has developed a set of tools to study nonlinear dynamics in a particle accelerator. The design of rings with large dynamic apertures is still far from automatic. The Working Group has concluded that nonlinear single-particle dynamics limits the performance of accelerators. (AIP) copyright 1999 American Institute of Physics

Fourier Transform Near Infrared Microspectroscopy, Infrared Chemical Imaging, High-Resolution Nuclear Magnetic Resonance and Fluorescence Microspectroscopy Detection of Single Cancer Cells and Single Viral Particles

CERN Document Server

Baianu,I C; Hofmann, N E; Korban, S S; Lozano, P; You, T

2004-01-01

Single Cancer Cells from Human tumors are being detected and imaged by Fourier Transform Infrared (FT-IR), Fourier Transform Near Infrared (FT-NIR)Hyperspectral Imaging and Fluorescence Correlation Microspectroscopy. The first FT-NIR chemical, microscopic images of biological systems approaching one micron resolution are here reported. Chemical images obtained by FT-NIR and FT-IR Microspectroscopy are also presented for oil in soybean seeds and somatic embryos under physiological conditions. FT-NIR spectra of oil and proteins were obtained for volumes as small as two cubic microns. Related, HR-NMR analyses of oil contents in somatic embryos as well as 99% accurate calibrations are also presented here with nanoliter precision. Such high-resolution, 400 MHz H-1 NMR analyses allowed the selection of mutagenized embryos with higher oil content (e.g. >~20%) compared to the average levels in non-mutagenized control embryos. Moreover, developmental changes in single soybean seeds and/or somatic embryos may be monito...

Video-rate confocal microscopy for single-molecule imaging in live cells and superresolution fluorescence imaging.

Science.gov (United States)

Lee, Jinwoo; Miyanaga, Yukihiro; Ueda, Masahiro; Hohng, Sungchul

2012-10-17

There is no confocal microscope optimized for single-molecule imaging in live cells and superresolution fluorescence imaging. By combining the swiftness of the line-scanning method and the high sensitivity of wide-field detection, we have developed a, to our knowledge, novel confocal fluorescence microscope with a good optical-sectioning capability (1.0 μm), fast frame rates (fluorescence detection efficiency. Full compatibility of the microscope with conventional cell-imaging techniques allowed us to do single-molecule imaging with a great ease at arbitrary depths of live cells. With the new microscope, we monitored diffusion motion of fluorescently labeled cAMP receptors of Dictyostelium discoideum at both the basal and apical surfaces and obtained superresolution fluorescence images of microtubules of COS-7 cells at depths in the range 0-85 μm from the surface of a coverglass. Copyright © 2012 Biophysical Society. Published by Elsevier Inc. All rights reserved.

Single Fluorescent Molecules as Nano-Illuminators for Biological Structure and Function

Science.gov (United States)

Moerner, W. E.

2011-03-01

Since the first optical detection and spectroscopy of a single molecule in a solid (Phys. Rev. Lett. {62}, 2535 (1989)), much has been learned about the ability of single molecules to probe local nanoenvironments and individual behavior in biological and nonbiological materials in the absence of ensemble averaging that can obscure heterogeneity. Because each single fluorophore acts a light source roughly 1 nm in size, microscopic imaging of individual fluorophores leads naturally to superlocalization, or determination of the position of the molecule with precision beyond the optical diffraction limit, simply by digitization of the point-spread function from the single emitter. For example, the shape of single filaments in a living cell can be extracted simply by allowing a single molecule to move through the filament (PNAS {103}, 10929 (2006)). The addition of photoinduced control of single-molecule emission allows imaging beyond the diffraction limit (super-resolution) and a new array of acronyms (PALM, STORM, F-PALM etc.) and advances have appeared. We have used the native blinking and switching of a common yellow-emitting variant of green fluorescent protein (EYFP) reported more than a decade ago (Nature {388}, 355 (1997)) to achieve sub-40 nm super-resolution imaging of several protein structures in the bacterium Caulobacter crescentus: the quasi-helix of the actin-like protein MreB (Nat. Meth. {5}, 947 (2008)), the cellular distribution of the DNA binding protein HU (submitted), and the recently discovered division spindle composed of ParA filaments (Nat. Cell Biol. {12}, 791 (2010)). Even with these advances, better emitters would provide more photons and improved resolution, and a new photoactivatable small-molecule emitter has recently been synthesized and targeted to specific structures in living cells to provide super-resolution images (JACS {132}, 15099 (2010)). Finally, a new optical method for extracting three-dimensional position information based on

ANTS-anchored Zn-Al-CO{sub 3}-LDH particles as fluorescent probe for sensing of folic acid

Energy Technology Data Exchange (ETDEWEB)

Liu, Pengfei; Liu, Dan; Liu, Yanhuan [State Key Laboratory of Chemical Resource Engineering, Beijing University of Chemical Technology, Beijing 100029 (China); Beijing Key Laboratory of Environmentally Harmful Chemical Analysis, Beijing University of Chemical Technology, Beijing 100029 (China); Li, Lei, E-mail: lilei@mail.buct.edu.cn [State Key Laboratory of Chemical Resource Engineering, Beijing University of Chemical Technology, Beijing 100029 (China); Beijing Key Laboratory of Environmentally Harmful Chemical Analysis, Beijing University of Chemical Technology, Beijing 100029 (China)

2016-09-15

A novel fluorescent nanosensor for detecting folic acid (FA) in aqueous media has been developed based on 8-aminonaphthalene-1,3,6-trisulfonate (ANTS) anchored to the surface of Zn-Al-CO{sub 3}-layered double hydroxides (LDH) particles. The nanosensor showed high fluorescence intensity and good photostability due to a strong coordination interaction between surface Zn{sup 2+} ions of Zn-Al-CO{sub 3}-LDH and N atoms of ANTS, which were verified by result of X-ray photoelectron spectroscopy (XPS). ANTS-anchored on the surface of Zn-Al-CO{sub 3}-LDH restricted the intra-molecular rotation leading to ANTS-anchored J-type aggregation emission enhancement. ANTS-anchored Zn-Al-CO{sub 3}-LDH particles exhibited highly sensitive and selective response to FA over other common metal ions and saccharides present in biological fluids. The proposed mechanism was that oxygen atoms of -SO{sub 3} groups in ANTS-anchored on the surface of Zn-Al-CO{sub 3}-LDH were easily collided by FA molecules to form potential hydrogen bonds between ANTS-anchored and FA molecules, which could effectively quench the ANTS-anchored fluorescence. Under the simulated physiological conditions (pH of 7.4), the fluorescence quenching was fitted to Stern-Volmer equation with a linear response in the concentration range of 1 μM to 200 μM with a limit of detection of 0.1 μM. The results indicate that ANTS-anchored Zn-Al-CO{sub 3}-LDH particles can afford a very sensitive system for the sensing FA in aqueous solution. - Highlights: • A novel fluorescent nanosensor has been developed. • The sensor exhibited highly sensitive and selective response to FA. • The fluorescence quenching was fitted to Stern–Volmer equation. • The linear response range was 1–200 μM with a limit of detection of 0.1 μM.

Evolution of single-particle structure of silicon isotopes

Science.gov (United States)

Bespalova, O. V.; Fedorov, N. A.; Klimochkina, A. A.; Markova, M. L.; Spasskaya, T. I.; Tretyakova, T. Yu.

2018-01-01

New data on proton and neutron single-particle energies E_{nlj} of Si isotopes with neutron number N from 12 to 28 as well as occupation probabilities N_{nlj} of single-particle states of stable isotopes 28, 30Si near the Fermi energy were obtained by the joint evaluation of the stripping and pick-up reaction data and excited state decay schemes of neighboring nuclei. The evaluated data indicate the following features of single-particle structure evolution: persistence of Z = 14 subshell closure with N increase, the new magicity of the number N = 16, and the conservation of the magic properties of the number N = 20 in Si isotopic chain. The features were described by the dispersive optical model. The calculation also predicts the weakening of N = 28 shell closure and demonstrates evolution of a bubble-like structure of the proton density distributions in neutron-rich Si isotopes.

Towards real time spatially resolved data on sediment transport: 1) tracing the motion of the fluorescent soil particles under rainfall

Science.gov (United States)

Quinton, John; Hardy, Rob; Pates, Jackie; James, Mike

2017-04-01

distance and direction of travel. In a second abstract we report on the field application of the tracer at the hillslope scale during a tillage erosion experiment. Here we trialled both intensity based and particle counting methodologies for tracer enumeration. After simulating seven years of tillage on a hillslope we were able to precisely determine the distribution of the fluorescent tracer and also its incorporation and distribution within the soil profile. Single grains of tracer could be found over 35 m from the insertion point.

Resonance fluorescence and quantum jumps in single atoms: Testing the randomness of quantum mechanics

International Nuclear Information System (INIS)

Erber, T.; Hammerling, P.; Hockney, G.; Porrati, M.; Putterman, S.; La Jolla Institute, La Jolla, California 92037; Department of Physics, University of California, Los Angeles, California 90024)

1989-01-01

When a single trapped 198 Hg + ion is illuminated by two lasers, each tuned to an approximate transition, the resulting fluorescence switches on and off in a series of pulses resembling a bistable telegraph. This intermittent fluorescence can also be obtained by optical pumping with a single laser. Quantum jumps between successive atomic levels may be traced directly with multiple-resonance fluorescence. Atomic transition rates and photon antibunching distributions can be inferred from the pulse statistics and compared with quantum theory. Stochastic tests also indicate that the quantum telegraphs are good random number generators. During periods when the fluorescence is switched off, the radiationless atomic currents that generate the telegraph signals can be adjusted by varying the laser illumination: if this coherent evolution of the wave functions is sustained over sufficiently long time intervals, novel interactive precision measurements, near the limits of the time-energy uncertainty relations, are possible. Copyright 1989 Academic Press, Inc

NIR-emitting molecular-based nanoparticles as new two-photon absorbing nanotools for single particle tracking

Science.gov (United States)

Daniel, J.; Godin, A. G.; Clermont, G.; Lounis, B.; Cognet, L.; Blanchard-Desce, M.

2015-07-01

In order to provide a green alternative to QDs for bioimaging purposes and aiming at designing bright nanoparticles combining both large one- and two-photon brightness, a bottom-up route based on the molecular engineering of dedicated red to NIR emitting dyes that spontaneously form fluorescent organic nanoparticles (FONs) has been implemented. These fully organic nanoparticles built from original quadrupolar dyes are prepared using a simple, expeditious and green protocol that yield very small molecular-based nanoparticles (radius ~ 7 nm) suspension in water showing a nice NIR emission (λem=710 nm). These FONs typically have absorption coefficient more than two orders larger than popular NIR-emitting dyes (such as Alexa Fluor 700, Cy5.5 ….) and much larger Stokes shift values (i.e. up to over 5500 cm-1). They also show very large two-photon absorption response in the 800-1050 nm region (up to about 106 GM) of major promise for two-photon excited fluorescence microscopy. Thanks to their brightness and enhanced photostability, these FONs could be imaged as isolated nanoparticles and tracked using wide-field imaging. As such, thanks to their size and composition (absence of heavy metals), they represent highly promising alternatives to NIR-emitting QDs for use in bioimaging and single particle tracking applications. Moreover, efficient FONs coating was achieved by using a polymeric additive built from a long hydrophobic (PPO) and a short hydrophilic (PEO) segment and having a cationic head group able to interact with the highly negative surface of FONs. This electrostatically-driven interaction promotes both photoluminescence and two-photon absorption enhancement leading to an increase of two-photon brightness of about one order of magnitude. This opens the way to wide-field single particle tracking under two-photon excitation

Physical aspects of quantitative particles analysis by X-ray fluorescence and electron microprobe techniques

International Nuclear Information System (INIS)

Markowicz, A.

1986-01-01

The aim of this work is to present both physical fundamentals and recent advances in quantitative particles analysis by X-ray fluorescence (XRF) and electron microprobe (EPXMA) techniques. A method of correction for the particle-size effect in XRF analysis is described and theoretically evaluated. New atomic number- and absorption correction procedures in EPXMA of individual particles are proposed. The applicability of these two correction methods is evaluated for a wide range of elemental composition, X-ray energy and sample thickness. Also, a theoretical model for composition and thickness dependence of Bremsstrahlung background generated in multielement bulk specimens as well as thin films and particles are presented and experimantally evaluated. Finally, the limitations and further possible improvements in quantitative particles analysis by XFR and EPXMA are discussed. 109 refs. (author)

Single-particle characterization of 'Asian Dust' certified reference materials using low-Z particle electron probe X-ray microanalysis

International Nuclear Information System (INIS)

Hwang, Hee Jin; Ro, Chul-Un

2006-01-01

In order to clearly elucidate whether Asian Dust particles experience chemical modification during long-range transport, it is necessary to characterize soil particles where Asian Dust particles originate. If chemical compositions of source soil particles are well characterized, then chemical compositions of Asian Dust particles collected outside source regions can be compared with those of source soil particles in order to find out the occurrence of chemical modification. Asian Dust particles are chemically and morphologically heterogeneous, and thus the average composition and the average aerodynamic diameter (obtainable by bulk analysis) are not much relevant if the chemical modifications of the particles must be followed. The major elemental composition and abundance of the particle types that are potential subjects of chemical modification can only be obtained using single-particle analysis. A single particle analytical technique, named low-Z particle electron probe X-ray microanalysis (low-Z particle EPMA), was applied to characterize two certified reference materials (CRMs) for Asian Dust particles, which were collected from a loess plateau area and a desert of China. The CRMs were defined by bulk analyses to provide certified concentrations for 13 chemical elements. Using the low-Z particle EPMA technique, the concentrations of major chemical species such as aluminosilicates, SiO 2 , CaCO 3 , and carbonaceous species were obtained. Elemental concentrations obtained by the low-Z particle EPMA are close to the certified values, with considering that the single particle and bulk analyses employ very different approaches. There are still some discrepancies between those concentration values, resulting from analyses of particles with different sizes, different sample amounts analyzed, and uncertainties involved in the single particle analysis

Evolution of single-particle structure of silicon isotopes

Energy Technology Data Exchange (ETDEWEB)

Bespalova, O.V.; Klimochkina, A.A.; Spasskaya, T.I.; Tretyakova, T.Yu. [Lomonosov Moscow State University, Skobeltsyn Institute of Nuclear Physics, Moscow (Russian Federation); Fedorov, N.A.; Markova, M.L. [Lomonosov Moscow State University, Faculty of Physics, Moscow (Russian Federation)

2018-01-15

New data on proton and neutron single-particle energies E{sub nlj} of Si isotopes with neutron number N from 12 to 28 as well as occupation probabilities N{sub nlj} of single-particle states of stable isotopes {sup 28,30}Si near the Fermi energy were obtained by the joint evaluation of the stripping and pick-up reaction data and excited state decay schemes of neighboring nuclei. The evaluated data indicate the following features of single-particle structure evolution: persistence of Z = 14 subshell closure with N increase, the new magicity of the number N = 16, and the conservation of the magic properties of the number N = 20 in Si isotopic chain. The features were described by the dispersive optical model. The calculation also predicts the weakening of N = 28 shell closure and demonstrates evolution of a bubble-like structure of the proton density distributions in neutron-rich Si isotopes. (orig.)

Fragmentation of single-particle states in deformed nuclei

International Nuclear Information System (INIS)

Malov, L.A.; Soloviev, V.G.

1975-01-01

Fragmentation of single-particle states on levels of deformed nuclei is studied on the example of 239 U and 169 Er nuclei in the framework of the model taking into consideration the interaction of quasiparticles with phonons. The dependence of fragmentation on the Fermi surface is considered from the viewpoint of single-particle levels. It is shown that in the distribution of single-particle strength functions a second maximum appears together with the large asymmetry maximum at high-energy excitation, and the distribution has a long ''tail''. A semimicroscopic approach is proposed for calculating the neutron strength functions. The following values of the strength functions are obtained: for sub(239)U-Ssub(0)sup(cal)=1.2x10sup(-4), Ssub(1)sup(cal)=2.7x10sub(-4) and for sub(169)Er-Ssub(0)sup(cal)=1.10sup(-4), Ssub(1)sup(cal)=1.2x10sup(-4)

Modeling of calcination of single kaolinitic clay particle

DEFF Research Database (Denmark)

Gebremariam, Abraham Teklay; Yin, Chungen; Rosendahl, Lasse

The present work aims at modeling of the calcination (dehydroxylation) process of clay particles, specifically kaolinite, and its thermal transformation. For such purpose, 1D single particle calcination model was developed based on the concept of shrinking core model to assess the dehydroxylation...

Semiempirical formulas for single-particle energies of neutrons and protons

International Nuclear Information System (INIS)

Lodhi, M.A.K.; Waak, B.T.

1978-01-01

The stepwise multiple linear regression technique has been used to analyze the single-particle energies of neutrons and protons in nuclei along the line of beta stability. Their regular and systematic trends lead to semiempirical model-independent formulas for single-particle energies of neutrons and protons in the bound nuclei as functions of nuclear parameters A and Z for given states specified by nl/sub j/. These formulas are almost as convenient as the harmonic oscillator energy formulas to use. The single-particle energies computed from these formulas have been compared with the experimental data and are found in reasonable agreement

Plasmonics Enhanced Smartphone Fluorescence Microscopy

KAUST Repository

Wei, Qingshan

2017-05-12

Smartphone fluorescence microscopy has various applications in point-of-care (POC) testing and diagnostics, ranging from e.g., quantification of immunoassays, detection of microorganisms, to sensing of viruses. An important need in smartphone-based microscopy and sensing techniques is to improve the detection sensitivity to enable quantification of extremely low concentrations of target molecules. Here, we demonstrate a general strategy to enhance the detection sensitivity of a smartphone-based fluorescence microscope by using surface-enhanced fluorescence (SEF) created by a thin metal-film. In this plasmonic design, the samples are placed on a silver-coated glass slide with a thin spacer, and excited by a laser-diode from the backside through a glass hemisphere, generating surface plasmon polaritons. We optimized this mobile SEF system by tuning the metal-film thickness, spacer distance, excitation angle and polarization, and achieved ~10-fold enhancement in fluorescence intensity compared to a bare glass substrate, which enabled us to image single fluorescent particles as small as 50 nm in diameter and single quantum-dots. Furthermore, we quantified the detection limit of this platform by using DNA origami-based brightness standards, demonstrating that ~80 fluorophores per diffraction-limited spot can be readily detected by our mobile microscope, which opens up new opportunities for POC diagnostics and sensing applications in resource-limited-settings.

Plasmonics Enhanced Smartphone Fluorescence Microscopy

KAUST Repository

Wei, Qingshan; Acuna, Guillermo; Kim, Seungkyeum; Vietz, Carolin; Tseng, Derek; Chae, Jongjae; Shir, Daniel; Luo, Wei; Tinnefeld, Philip; Ozcan, Aydogan

2017-01-01

Smartphone fluorescence microscopy has various applications in point-of-care (POC) testing and diagnostics, ranging from e.g., quantification of immunoassays, detection of microorganisms, to sensing of viruses. An important need in smartphone-based microscopy and sensing techniques is to improve the detection sensitivity to enable quantification of extremely low concentrations of target molecules. Here, we demonstrate a general strategy to enhance the detection sensitivity of a smartphone-based fluorescence microscope by using surface-enhanced fluorescence (SEF) created by a thin metal-film. In this plasmonic design, the samples are placed on a silver-coated glass slide with a thin spacer, and excited by a laser-diode from the backside through a glass hemisphere, generating surface plasmon polaritons. We optimized this mobile SEF system by tuning the metal-film thickness, spacer distance, excitation angle and polarization, and achieved ~10-fold enhancement in fluorescence intensity compared to a bare glass substrate, which enabled us to image single fluorescent particles as small as 50 nm in diameter and single quantum-dots. Furthermore, we quantified the detection limit of this platform by using DNA origami-based brightness standards, demonstrating that ~80 fluorophores per diffraction-limited spot can be readily detected by our mobile microscope, which opens up new opportunities for POC diagnostics and sensing applications in resource-limited-settings.

Experiments and modeling of single plastic particle conversion in suspension

DEFF Research Database (Denmark)

Nakhaei, Mohammadhadi; Wu, Hao; Grévain, Damien

2018-01-01

Conversion of single high density polyethylene (PE) particles has been studied by experiments and modeling. The experiments were carried out in a single particle combustor for five different shapes and masses of particles at temperature conditions of 900 and 1100°C. Each experiment was recorded...... against the experiments as well as literature data. Furthermore, a simplified isothermal model appropriate for CFD applications was developed, in order to model the combustion of plastic particles in cement calciners. By comparing predictions with the isothermal and the non–isothermal models under typical...

Single-Labeled Oligonucleotides Showing Fluorescence Changes upon Hybridization with Target Nucleic Acids

Directory of Open Access Journals (Sweden)

Gil Tae Hwang

2018-01-01

Full Text Available Sequence-specific detection of nucleic acids has been intensively studied in the field of molecular diagnostics. In particular, the detection and analysis of single-nucleotide polymorphisms (SNPs is crucial for the identification of disease-causing genes and diagnosis of diseases. Sequence-specific hybridization probes, such as molecular beacons bearing the fluorophore and quencher at both ends of the stem, have been developed to enable DNA mutation detection. Interestingly, DNA mutations can be detected using fluorescently labeled oligonucleotide probes with only one fluorophore. This review summarizes recent research on single-labeled oligonucleotide probes that exhibit fluorescence changes after encountering target nucleic acids, such as guanine-quenching probes, cyanine-containing probes, probes containing a fluorophore-labeled base, and microenvironment-sensitive probes.

Demonstration of Single-Barium-Ion Sensitivity for Neutrinoless Double-Beta Decay Using Single-Molecule Fluorescence Imaging

Energy Technology Data Exchange (ETDEWEB)

McDonald, A. D.; Jones, B. J. P.; Nygren, D. R.; Adams, C.; Álvarez, V.; Azevedo, C. D. R.; Benlloch-Rodríguez, J. M.; Borges, F. I. G. M.; Botas, A.; Cárcel, S.; Carrión, J. V.; Cebrián, S.; Conde, C. A. N.; Díaz, J.; Diesburg, M.; Escada, J.; Esteve, R.; Felkai, R.; Fernandes, L. M. P.; Ferrario, P.; Ferreira, A. L.; Freitas, E. D. C.; Goldschmidt, A.; Gómez-Cadenas, J. J.; González-Díaz, D.; Gutiérrez, R. M.; Guenette, R.; Hafidi, K.; Hauptman, J.; Henriques, C. A. O.; Hernandez, A. I.; Hernando Morata, J. A.; Herrero, V.; Johnston, S.; Labarga, L.; Laing, A.; Lebrun, P.; Liubarsky, I.; López-March, N.; Losada, M.; Martín-Albo, J.; Martínez-Lema, G.; Martínez, A.; Monrabal, F.; Monteiro, C. M. B.; Mora, F. J.; Moutinho, L. M.; Muñoz Vidal, J.; Musti, M.; Nebot-Guinot, M.; Novella, P.; Palmeiro, B.; Para, A.; Pérez, J.; Querol, M.; Repond, J.; Renner, J.; Riordan, S.; Ripoll, L.; Rodríguez, J.; Rogers, L.; Santos, F. P.; dos Santos, J. M. F.; Simón, A.; Sofka, C.; Sorel, M.; Stiegler, T.; Toledo, J. F.; Torrent, J.; Tsamalaidze, Z.; Veloso, J. F. C. A.; Webb, R.; White, J. T.; Yahlali, N.

2018-03-01

A new method to tag the barium daughter in the double beta decay of $^{136}$Xe is reported. Using the technique of single molecule fluorescent imaging (SMFI), individual barium dication (Ba$^{++}$) resolution at a transparent scanning surface has been demonstrated. A single-step photo-bleach confirms the single ion interpretation. Individual ions are localized with super-resolution ($\\sim$2~nm), and detected with a statistical significance of 12.9~$\\sigma$ over backgrounds. This lays the foundation for a new and potentially background-free neutrinoless double beta decay technology, based on SMFI coupled to high pressure xenon gas time projection chambers.

Demonstration of Single-Barium-Ion Sensitivity for Neutrinoless Double-Beta Decay Using Single-Molecule Fluorescence Imaging

Science.gov (United States)

McDonald, A. D.; Jones, B. J. P.; Nygren, D. R.; Adams, C.; Álvarez, V.; Azevedo, C. D. R.; Benlloch-Rodríguez, J. M.; Borges, F. I. G. M.; Botas, A.; Cárcel, S.; Carrión, J. V.; Cebrián, S.; Conde, C. A. N.; Díaz, J.; Diesburg, M.; Escada, J.; Esteve, R.; Felkai, R.; Fernandes, L. M. P.; Ferrario, P.; Ferreira, A. L.; Freitas, E. D. C.; Goldschmidt, A.; Gómez-Cadenas, J. J.; González-Díaz, D.; Gutiérrez, R. M.; Guenette, R.; Hafidi, K.; Hauptman, J.; Henriques, C. A. O.; Hernandez, A. I.; Hernando Morata, J. A.; Herrero, V.; Johnston, S.; Labarga, L.; Laing, A.; Lebrun, P.; Liubarsky, I.; López-March, N.; Losada, M.; Martín-Albo, J.; Martínez-Lema, G.; Martínez, A.; Monrabal, F.; Monteiro, C. M. B.; Mora, F. J.; Moutinho, L. M.; Muñoz Vidal, J.; Musti, M.; Nebot-Guinot, M.; Novella, P.; Palmeiro, B.; Para, A.; Pérez, J.; Querol, M.; Repond, J.; Renner, J.; Riordan, S.; Ripoll, L.; Rodríguez, J.; Rogers, L.; Santos, F. P.; dos Santos, J. M. F.; Simón, A.; Sofka, C.; Sorel, M.; Stiegler, T.; Toledo, J. F.; Torrent, J.; Tsamalaidze, Z.; Veloso, J. F. C. A.; Webb, R.; White, J. T.; Yahlali, N.; NEXT Collaboration

2018-03-01

A new method to tag the barium daughter in the double-beta decay of Xe 136 is reported. Using the technique of single molecule fluorescent imaging (SMFI), individual barium dication (Ba++ ) resolution at a transparent scanning surface is demonstrated. A single-step photobleach confirms the single ion interpretation. Individual ions are localized with superresolution (˜2 nm ), and detected with a statistical significance of 12.9 σ over backgrounds. This lays the foundation for a new and potentially background-free neutrinoless double-beta decay technology, based on SMFI coupled to high pressure xenon gas time projection chambers.

Revealing the Raft Domain Organization in the Plasma Membrane by Single-Molecule Imaging of Fluorescent Ganglioside Analogs.

Science.gov (United States)

Suzuki, Kenichi G N; Ando, Hiromune; Komura, Naoko; Konishi, Miku; Imamura, Akihiro; Ishida, Hideharu; Kiso, Makoto; Fujiwara, Takahiro K; Kusumi, Akihiro

2018-01-01

Gangliosides have been implicated in a variety of physiological processes, particularly in the formation and function of raft domains in the plasma membrane. However, the scarcity of suitable fluorescent ganglioside analogs had long prevented us from determining exactly how gangliosides perform their functions in the live-cell plasma membrane. With the development of new fluorescent ganglioside analogs, as described by Komura et al. (2017), this barrier has been broken. We can now address the dynamic behaviors of gangliosides in the live-cell plasma membrane, using fluorescence microscopy, particularly by single-fluorescent molecule imaging and tracking. Single-molecule tracking of fluorescent GM1 and GM3 revealed that these molecules are transiently and dynamically recruited to monomers (monomer-associated rafts) and homodimer rafts of the raftophilic GPI-anchored protein CD59 in quiescent cells, with exponential residency times of 12 and 40ms, respectively, in a manner dependent on raft-lipid interactions. Upon CD59 stimulation, which induces CD59-cluster signaling rafts, the fluorescent GM1 and GM3 analogs were recruited to the signaling rafts, with a lifetime of 48ms. These results represent the first direct evidence that GPI-anchored receptors and gangliosides interact in a cholesterol-dependent manner. Furthermore, they show that gangliosides continually move in and out of rafts that contain CD59 in an extremely dynamic manner, with much higher frequency than expected previously. Such studies would not have been possible without fluorescent ganglioside probes, which exhibit native-like behavior and single-molecule tracking. In this chapter, we review the methods for single-molecule tracking of fluorescent ganglioside analogs and the results obtained by applying these methods. © 2018 Elsevier Inc. All rights reserved.

Single particle composition measurements of artificial Calcium Carbonate aerosols

Science.gov (United States)

Zorn, S. R.; Mentel, T. F.; Schwinger, T.; Croteau, P. L.; Jayne, J.; Worsnop, D. R.; Trimborn, A.

2012-12-01

Mineral dust, with an estimated total source from natural and anthropogenic emissions of up to 2800 Tg/yr, is one of the two largest contributors to total aerosol mass, with only Sea salt having a similar source strength (up to 2600 Tg/yr). The composition of dust particles varies strongly depending on the production process and, most importantly, the source location. Therefore, the composition of single dust particles can be used both to trace source regions of air masses as well as to identify chemical aging processes. Here we present results of laboratory studies on generating artificial calcium carbonate (CaCO3) particles, a model compound for carbonaceous mineral dust particles. Particles were generated by atomizing an aqueous hydrogen carbonate solution. Water was removed using a silica diffusion dryer., then the particles were processed in an oven at temperatures up to 900°C, converting the hydrogen carbonate to its anhydrous form. The resulting aerosol was analyzed using an on-line single particle laser ablation aerosol particle time-of-flight mass spectrometer (LAAPTOF). The results confirm the conversion to calcium carbonate, and validate that the produced particles indeed can be used as a model compound for carbonaceous dust aerosols.

Fluorescent carbon nanoparticles derived from natural materials of mango fruit for bio-imaging probes

Science.gov (United States)

Jeong, Chan Jin; Roy, Arup Kumer; Kim, Sung Han; Lee, Jung-Eun; Jeong, Ji Hoon; Insik; Park, Sung Young

2014-11-01

Water soluble fluorescent carbon nanoparticles (FCP) obtained from a single natural source, mango fruit, were developed as unique materials for non-toxic bio-imaging with different colors and particle sizes. The prepared FCPs showed blue (FCP-B), green (FCP-G) and yellow (FCP-Y) fluorescence, derived by the controlled carbonization method. The FCPs demonstrated hydrodynamic diameters of 5-15 nm, holding great promise for clinical applications. The biocompatible FCPs demonstrated great potential in biological fields through the results of in vitro imaging and in vivo biodistribution. Using intravenously administered FCPs with different colored particles, we precisely defined the clearance and biodistribution, showing rapid and efficient urinary excretion for safe elimination from the body. These findings therefore suggest the promising possibility of using natural sources for producing fluorescent materials.Water soluble fluorescent carbon nanoparticles (FCP) obtained from a single natural source, mango fruit, were developed as unique materials for non-toxic bio-imaging with different colors and particle sizes. The prepared FCPs showed blue (FCP-B), green (FCP-G) and yellow (FCP-Y) fluorescence, derived by the controlled carbonization method. The FCPs demonstrated hydrodynamic diameters of 5-15 nm, holding great promise for clinical applications. The biocompatible FCPs demonstrated great potential in biological fields through the results of in vitro imaging and in vivo biodistribution. Using intravenously administered FCPs with different colored particles, we precisely defined the clearance and biodistribution, showing rapid and efficient urinary excretion for safe elimination from the body. These findings therefore suggest the promising possibility of using natural sources for producing fluorescent materials. Electronic supplementary information (ESI) available. See DOI: 10.1039/c4nr04805a

Versatile single-molecule multi-color excitation and detection fluorescence setup for studying biomolecular dynamics

KAUST Repository

Sobhy, M. A.

2011-11-07

Single-molecule fluorescence imaging is at the forefront of tools applied to study biomolecular dynamics both in vitro and in vivo. The ability of the single-molecule fluorescence microscope to conduct simultaneous multi-color excitation and detection is a key experimental feature that is under continuous development. In this paper, we describe in detail the design and the construction of a sophisticated and versatile multi-color excitation and emission fluorescence instrument for studying biomolecular dynamics at the single-molecule level. The setup is novel, economical and compact, where two inverted microscopes share a laser combiner module with six individual laser sources that extend from 400 to 640 nm. Nonetheless, each microscope can independently and in a flexible manner select the combinations, sequences, and intensities of the excitation wavelengths. This high flexibility is achieved by the replacement of conventional mechanical shutters with acousto-optic tunable filter (AOTF). The use of AOTF provides major advancement by controlling the intensities, duration, and selection of up to eight different wavelengths with microsecond alternation time in a transparent and easy manner for the end user. To our knowledge this is the first time AOTF is applied to wide-field total internal reflection fluorescence (TIRF) microscopy even though it has been commonly used in multi-wavelength confocal microscopy. The laser outputs from the combiner module are coupled to the microscopes by two sets of four single-mode optic fibers in order to allow for the optimization of the TIRF angle for each wavelength independently. The emission is split into two or four spectral channels to allow for the simultaneous detection of up to four different fluorophores of wide selection and using many possible excitation and photoactivation schemes. We demonstrate the performance of this new setup by conducting two-color alternating excitation single-molecule fluorescence resonance energy

Fundamental Study of Single Biomass Particle Combustion

DEFF Research Database (Denmark)

Momenikouchaksaraei, Maryam

This thesis is a comprehensive study of single biomass particle combustion. The effect of particle shape and size and operating conditions on biomass conversion characteristics were investigated experimentally and theoretically. The experimental samples were divided in two groups: particles...... well-defined conditions, and the complete combustion processes were recorded as video sequences by a CCD camera installed in the set-up. One of the project objectives is to simulate conditions reasonably close to the conditions in a power plant boiler, i.e., reasonably high temperatures (up to 1600°C...

Burnout of pulverized biomass particles in large scale boiler - Single particle model approach

Energy Technology Data Exchange (ETDEWEB)

Saastamoinen, Jaakko; Aho, Martti; Moilanen, Antero [VTT Technical Research Centre of Finland, Box 1603, 40101 Jyvaeskylae (Finland); Soerensen, Lasse Holst [ReaTech/ReAddit, Frederiksborgsveij 399, Niels Bohr, DK-4000 Roskilde (Denmark); Clausen, Soennik [Risoe National Laboratory, DK-4000 Roskilde (Denmark); Berg, Mogens [ENERGI E2 A/S, A.C. Meyers Vaenge 9, DK-2450 Copenhagen SV (Denmark)

2010-05-15

Burning of coal and biomass particles are studied and compared by measurements in an entrained flow reactor and by modelling. The results are applied to study the burning of pulverized biomass in a large scale utility boiler originally planned for coal. A simplified single particle approach, where the particle combustion model is coupled with one-dimensional equation of motion of the particle, is applied for the calculation of the burnout in the boiler. The particle size of biomass can be much larger than that of coal to reach complete burnout due to lower density and greater reactivity. The burner location and the trajectories of the particles might be optimised to maximise the residence time and burnout. (author)

Visualization of Content Release from Cell Surface-Attached Single HIV-1 Particles Carrying an Extra-Viral Fluorescent pH-Sensor.

Science.gov (United States)

Sood, Chetan; Marin, Mariana; Mason, Caleb S; Melikyan, Gregory B

2016-01-01

HIV-1 fusion leading to productive entry has long been thought to occur at the plasma membrane. However, our previous single virus imaging data imply that, after Env engagement of CD4 and coreceptors at the cell surface, the virus enters into and fuses with intracellular compartments. We were unable to reliably detect viral fusion at the plasma membrane. Here, we implement a novel virus labeling strategy that biases towards detection of virus fusion that occurs in a pH-neutral environment-at the plasma membrane or, possibly, in early pH-neutral vesicles. Virus particles are co-labeled with an intra-viral content marker, which is released upon fusion, and an extra-viral pH sensor consisting of ecliptic pHluorin fused to the transmembrane domain of ICAM-1. This sensor fully quenches upon virus trafficking to a mildly acidic compartment, thus precluding subsequent detection of viral content release. As an interesting secondary observation, the incorporation of the pH-sensor revealed that HIV-1 particles occasionally shuttle between neutral and acidic compartments in target cells expressing CD4, suggesting a small fraction of viral particles is recycled to the plasma membrane and re-internalized. By imaging viruses bound to living cells, we found that HIV-1 content release in neutral-pH environment was a rare event (~0.4% particles). Surprisingly, viral content release was not significantly reduced by fusion inhibitors, implying that content release was due to spontaneous formation of viral membrane defects occurring at the cell surface. We did not measure a significant occurrence of HIV-1 fusion at neutral pH above this defect-mediated background loss of content, suggesting that the pH sensor may destabilize the membrane of the HIV-1 pseudovirus and, thus, preclude reliable detection of single virus fusion events at neutral pH.

Visualization of Content Release from Cell Surface-Attached Single HIV-1 Particles Carrying an Extra-Viral Fluorescent pH-Sensor.

Directory of Open Access Journals (Sweden)

Chetan Sood

Full Text Available HIV-1 fusion leading to productive entry has long been thought to occur at the plasma membrane. However, our previous single virus imaging data imply that, after Env engagement of CD4 and coreceptors at the cell surface, the virus enters into and fuses with intracellular compartments. We were unable to reliably detect viral fusion at the plasma membrane. Here, we implement a novel virus labeling strategy that biases towards detection of virus fusion that occurs in a pH-neutral environment-at the plasma membrane or, possibly, in early pH-neutral vesicles. Virus particles are co-labeled with an intra-viral content marker, which is released upon fusion, and an extra-viral pH sensor consisting of ecliptic pHluorin fused to the transmembrane domain of ICAM-1. This sensor fully quenches upon virus trafficking to a mildly acidic compartment, thus precluding subsequent detection of viral content release. As an interesting secondary observation, the incorporation of the pH-sensor revealed that HIV-1 particles occasionally shuttle between neutral and acidic compartments in target cells expressing CD4, suggesting a small fraction of viral particles is recycled to the plasma membrane and re-internalized. By imaging viruses bound to living cells, we found that HIV-1 content release in neutral-pH environment was a rare event (~0.4% particles. Surprisingly, viral content release was not significantly reduced by fusion inhibitors, implying that content release was due to spontaneous formation of viral membrane defects occurring at the cell surface. We did not measure a significant occurrence of HIV-1 fusion at neutral pH above this defect-mediated background loss of content, suggesting that the pH sensor may destabilize the membrane of the HIV-1 pseudovirus and, thus, preclude reliable detection of single virus fusion events at neutral pH.

Single Molecule Spectroscopy of Fluorescent Proteins

NARCIS (Netherlands)

Blum, Christian; Subramaniam, Vinod

2009-01-01

The discovery and use of fluorescent proteins has revolutionized cellular biology. Despite the widespread use of visible fluorescent proteins as reporters and sensors in cellular environments the versatile photophysics of fluorescent proteins is still subject to intense research. Understanding the

Fluorescence Quenching of Humic Acid by Coated Metallic Silver Particles.

Science.gov (United States)

Zhu, Guocheng; Yin, Jun

2017-07-01

Natural organic matter is an important component of the aquatic environments, which has attracted wide attention to its influence of interaction with other pollutants. The present work aimed to investigate its fluorescence quenching (FQ) by coated metallic silver particles (AgNPs). In this work, using fluorescence spectroscopy in conjunction with UV-Vis spectroscopy and dynamic light scattering, the effect of coated AgNPs on fluorescence quenching intensity (FQI) of humic acid (HA) was assessed. In addition, the influence of electrolytes (NaCl, NaNO 3 and CaNO 3 ) in the FQI was observed. Results showed that with AgNPs dosage increased (>1.17X10 -3  mM), fluorescence quantum yield of HA gradually decreased, which implies that the FQ occurred. Furher observation showed that the FQ process followed both first-order and second-order Stern-Volmer functions. The FQ process was affected by the electrolytes: NaCl had an effect on reduction of FQI, possibly resulting from dissolution of AgNPs; Both of NaNO 3 and Ca(NO 3 ) 2 had an effect on the FQ of HA but Ca(NO 3 ) 2 presented greater degree. As a result, the FQ degree of HA by alone electrolyte was listed in descent order as Ca(NO 3 ) 2  > NaNO 3  > NaCl, which also implies the subsequent experimental results, indicating the FQ degree of HA by mutual electrolytes as Ca(NO 3 ) 2  + NaNO 3  > Ca(NO 3 ) 2  + NaCl > NaNO 3  + NaCl.

Fluorescent scattering by molecules embedded in small particles. Progress report, February 1, 1981-January 31, 1982

International Nuclear Information System (INIS)

Chew, H.; McNulty, P.J.

1982-01-01

In earlier work a model of fluorescent and Raman scattering by active molecules represented as classical electric dipoles embedded in small particles was developed. The intensity and angular distribution of the inelastically scattered radiation was shown to depend on the geometric and optical properties of the particle. The model was originally developed for particles having spherical shape and later extended to concentric spheres, cylinders, and prolate spheroids. The active molecules were originally assumed to be isotropically polarizable. The model has been recently extended to certain types of anisotropically polarizable molecules. The model had also been applied to particles having internal structure

Generation and characterization of a stable cell population releasing fluorescent HIV-1-based Virus Like Particles in an inducible way

Directory of Open Access Journals (Sweden)

Bosch Valerie

2006-12-01

Full Text Available Abstract Background The availability of cell lines releasing fluorescent viral particles can significantly support a variety of investigations, including the study of virus-cell interaction and the screening of antiviral compounds. Regarding HIV-1, the recovery of such biologic reagents represents a very hard challenge due to the intrinsic cytotoxicity of many HIV-1 products. We sought to overcome such a limitation by using a cell line releasing HIV-1 particles in an inducible way, and by exploiting the ability of a HIV-1 Nef mutant to be incorporated in virions at quite high levels. Results Here, we report the isolation and characterization of a HIV-1 packaging cell line, termed 18-4s, able to release valuable amounts of fluorescent HIV-1 based Virus-Like Particles (VLPs in an inducible way. 18-4s cells were recovered by constitutively expressing the HIV-1 NefG3C mutant fused with the enhanced-green fluorescent protein (NefG3C-GFP in a previously isolated inducible HIV-1 packaging cell line. The G3C mutation creates a palmitoylation site which results in NefG3C-GFP incorporation into virions greatly exceeding that of the wild type counterpart. Upon induction of 18-4s cells with ponasterone A and sodium butyrate, up to 4 μg/ml of VLPs, which had incorporated about 150 molecules of NefG3C-GFP per viral particle, were released into the culture supernatant. Due to their intrinsic strong fluorescence, the 18-4s VLPs were easily detectable by a novel cytofluorometric-based assay developed here. The treatment of target cells with fluorescent 18-4 VLPs pseudotyped with different glycoprotein receptors resulted in these becoming fluorescent as early as two hours post-challenge. Conclusion We created a stable cell line releasing fluorescent HIV-1 based VLPs upon induction useful for several applications including the study of virus-cell interactions and the screening of antiviral compounds.

Laboratory Measurements of Single-Particle Polarimetric Spectrum

Science.gov (United States)

Gritsevich, M.; Penttila, A.; Maconi, G.; Kassamakov, I.; Helander, P.; Puranen, T.; Salmi, A.; Hæggström, E.; Muinonen, K.

2017-12-01

Measuring scattering properties of different targets is important for material characterization, remote sensing applications, and for verifying theoretical results. Furthermore, there are usually simplifications made when we model targets and compute the scattering properties, e.g., ideal shape or constant optical parameters throughout the target material. Experimental studies help in understanding the link between the observed properties and computed results. Experimentally derived Mueller matrices of studied particles can be used as input for larger-scale scattering simulations, e.g., radiative transfer computations. This method allows to bypass the problem of using an idealized model for single-particle optical properties. While existing approaches offer ensemble- and orientation-averaged particle properties, our aim is to measure individual particles with controlled or known orientation. With the newly developed scatterometer, we aim to offer novel possibility to measure single, small (down to μm-scale) targets and their polarimetric spectra. This work presents an experimental setup that measures light scattered by a fixed small particle with dimensions ranging between micrometer and millimeter sizes. The goal of our setup is nondestructive characterization of such particles by measuring light of multiple wavelengths scattered in 360° in a horizontal plane by an ultrasonically levitating sample, whilst simultaneously controlling its 3D position and orientation. We describe the principles and design of our instrument and its calibration. We also present example measurements of real samples. This study was conducted under the support from the European Research Council, in the frame of the Advanced Grant project No. 320773 `Scattering and Absorption of Electromagnetic Waves in Particulate Media' (SAEMPL).

Method for rapid multidiameter single-fiber reflectance and fluorescence spectroscopy through a fiber bundle

NARCIS (Netherlands)

Amelink, A.; Hoy, C.L.; Gamm, U.A.; Sterenborg, H.J.C.M.; Robinson, D.J.

2014-01-01

We have recently demonstrated a means for quantifying the absorption and scattering properties of biological tissue through multidiameter single-fiber reflectance (MDSFR) spectroscopy. These measurements can be used to correct single-fiber fluorescence (SFF) spectra for the influence of optical

Single particle analysis with a 3600 light scattering photometer

International Nuclear Information System (INIS)

Bartholdi, M.F.

1979-06-01

Light scattering by single spherical homogeneous particles in the diameter range 1 to 20 μm and relative refractive index 1.20 is measured. Particle size of narrowly dispersed populations is determined and a multi-modal dispersion of five components is completely analyzed. A 360 0 light scattering photometer for analysis of single particles has been designed and developed. A fluid stream containing single particles intersects a focused laser beam at the primary focal point of an ellipsoidal reflector ring. The light scattered at angles theta = 2.5 0 to 177.5 0 at phi = 0 0 and 180 0 is reflected onto a circular array of photodiodes. The ellipsoidal reflector is situated in a chamber filled with fluid matching that of the stream to minimize refracting and reflecting interfaces. The detector array consists of 60 photodiodes each subtending 3 0 in scattering angle on 6 0 centers around 360 0 . 32 measurements on individual particles can be acquired at rates of 500 particles per second. The intensity and angular distribution of light scattered by spherical particles are indicative of size and relative refractive index. Calculations, using Lorenz--Mie theory, of differential scattering patterns integrated over angle corresponding to the detector geometry determined the instrument response to particle size. From this the expected resolution and experimental procedures are determined.Ultimately, the photometer will be utilized for identification and discrimination of biological cells based on the sensitivity of light scattering to size, shape, refractive index differences, internal granularity, and other internal morphology. This study has demonstrated the utility of the photometer and indicates potential for application to light scattering studies of biological cells

Single-particle basis and translational invariance in microscopic nuclear calculations

International Nuclear Information System (INIS)

Ehfros, V.D.

1977-01-01

The approach to the few-body problem is considered which allows to use the simple single-particle basis without violation of the translation invariance. A method is proposed to solve the nuclear reaction problems in the single-particle basis. The method satisfies the Pauli principle and the translation invariance. Calculation of the matrix elements of operators is treated

Single-Shot, Volumetrically Illuminated, Three-Dimensional, Tomographic Laser-Induced-Fluorescence Imaging in a Gaseous Free Jet

Science.gov (United States)

2016-04-28

Single-shot, volumetrically illuminated, three- dimensional, tomographic laser-induced- fluorescence imaging in a gaseous free jet Benjamin R. Halls...acquisition; (110.6955) Tomographic imaging ; (110.6960) Tomography; (280.2490) Flow diagnostics; (300.2530) Fluorescence , laser-induced...84 (1983). 2. I. van Cruyningen, A. Lozano, and R. K. Hanson, “Quantitative imaging of concentration by planar laser-induced fluorescence ,” Exp

Factors Influencing the Ignition and Burnout of a Single Biomass Particle

DEFF Research Database (Denmark)

Momenikouchaksaraei, Maryam; Kær, Søren Knudsen; Yin, Chungen

2011-01-01

Ignition and burnout of a single biomass particle were studied numerically. A one-dimensional particle combustion model was developed which is capable to simulate all the intraparticle conversion processes (drying, recondensation, devolatilization, char gasification/oxidation and heat/mass/moment......Ignition and burnout of a single biomass particle were studied numerically. A one-dimensional particle combustion model was developed which is capable to simulate all the intraparticle conversion processes (drying, recondensation, devolatilization, char gasification/oxidation and heat...... concentration were not very significant. The influences of these factors on particle burnout were much more remarkable than ignition behaviour....

Design of new dusty plasma apparatus to view 3D particle dynamics of fluorescent dust clouds

Science.gov (United States)

Thome, Kathreen; Fontanetta, Alexandra; Zwicker, Andrew

2008-11-01

Particles suspended in dusty plasmas represent both contamination in industrial plasmas and a primary interstellar medium component. Typically, dusty plasma behavior is studied by laser scattering techniques that provide 2D dust cloud images. However, the 3D structure of the dust cloud is essential to understand the waves, group dynamics, and stabilities of the cloud. Techniques used to study this structure include stereoscopic particle image velocimetry and rapid laser scanning. Our UV illumination technique reveals translational and rotational velocities of fluorescent dust particles as a function of UV intensity. The new argon DC glow discharge experiment designed to study the 3D aspects of fluorescent dust consists of a 13.25'' diameter chamber, two 8'' window ports for CCD cameras, one along the plasma and another transverse to it, two additional 8'' window ports transverse to the plasma for laser or UV light illumination of the dust cloud, and a diagnostic probe port. Results from different electrodes--including mesh and ring--observations and imaging will be presented.

Two-Way Communication with a Single Quantum Particle

Science.gov (United States)

Del Santo, Flavio; Dakić, Borivoje

2018-02-01

In this Letter we show that communication when restricted to a single information carrier (i.e., single particle) and finite speed of propagation is fundamentally limited for classical systems. On the other hand, quantum systems can surpass this limitation. We show that communication bounded to the exchange of a single quantum particle (in superposition of different spatial locations) can result in "two-way signaling," which is impossible in classical physics. We quantify the discrepancy between classical and quantum scenarios by the probability of winning a game played by distant players. We generalize our result to an arbitrary number of parties and we show that the probability of success is asymptotically decreasing to zero as the number of parties grows, for all classical strategies. In contrast, quantum strategy allows players to win the game with certainty.

Snow particles extracted from X-ray computed microtomography imagery and their single-scattering properties

Science.gov (United States)

Ishimoto, Hiroshi; Adachi, Satoru; Yamaguchi, Satoru; Tanikawa, Tomonori; Aoki, Teruo; Masuda, Kazuhiko

2018-04-01

Sizes and shapes of snow particles were determined from X-ray computed microtomography (micro-CT) images, and their single-scattering properties were calculated at visible and near-infrared wavelengths using a Geometrical Optics Method (GOM). We analyzed seven snow samples including fresh and aged artificial snow and natural snow obtained from field samples. Individual snow particles were numerically extracted, and the shape of each snow particle was defined by applying a rendering method. The size distribution and specific surface area distribution were estimated from the geometrical properties of the snow particles, and an effective particle radius was derived for each snow sample. The GOM calculations at wavelengths of 0.532 and 1.242 μm revealed that the realistic snow particles had similar scattering phase functions as those of previously modeled irregular shaped particles. Furthermore, distinct dendritic particles had a characteristic scattering phase function and asymmetry factor. The single-scattering properties of particles of effective radius reff were compared with the size-averaged single-scattering properties. We found that the particles of reff could be used as representative particles for calculating the average single-scattering properties of the snow. Furthermore, the single-scattering properties of the micro-CT particles were compared to those of particle shape models using our current snow retrieval algorithm. For the single-scattering phase function, the results of the micro-CT particles were consistent with those of a conceptual two-shape model. However, the particle size dependence differed for the single-scattering albedo and asymmetry factor.

Mass spectra features of biomass burning boiler and coal burning boiler emitted particles by single particle aerosol mass spectrometer.

Science.gov (United States)

Xu, Jiao; Li, Mei; Shi, Guoliang; Wang, Haiting; Ma, Xian; Wu, Jianhui; Shi, Xurong; Feng, Yinchang

2017-11-15

In this study, single particle mass spectra signatures of both coal burning boiler and biomass burning boiler emitted particles were studied. Particle samples were suspended in clean Resuspension Chamber, and analyzed by ELPI and SPAMS simultaneously. The size distribution of BBB (biomass burning boiler sample) and CBB (coal burning boiler sample) are different, as BBB peaks at smaller size, and CBB peaks at larger size. Mass spectra signatures of two samples were studied by analyzing the average mass spectrum of each particle cluster extracted by ART-2a in different size ranges. In conclusion, BBB sample mostly consists of OC and EC containing particles, and a small fraction of K-rich particles in the size range of 0.2-0.5μm. In 0.5-1.0μm, BBB sample consists of EC, OC, K-rich and Al_Silicate containing particles; CBB sample consists of EC, ECOC containing particles, while Al_Silicate (including Al_Ca_Ti_Silicate, Al_Ti_Silicate, Al_Silicate) containing particles got higher fractions as size increase. The similarity of single particle mass spectrum signatures between two samples were studied by analyzing the dot product, results indicated that part of the single particle mass spectra of two samples in the same size range are similar, which bring challenge to the future source apportionment activity by using single particle aerosol mass spectrometer. Results of this study will provide physicochemical information of important sources which contribute to particle pollution, and will support source apportionment activities. Copyright © 2017. Published by Elsevier B.V.

Development of real time detector for fluorescent particles applied to pollutant transfers characterization; Etude d`un dispositif de comptage en continu d`un aerosol fluorescent

Energy Technology Data Exchange (ETDEWEB)

Prevost, C [CEA Saclay, Departement de Prevention et d` Etude des Accidents, 91 - Gif-sur-Yvette (France); [Conservatoire National des Arts et Metiers (CNAM), 75 - Paris (France)

1996-06-01

The studies on aerosol transfer carried out in the field of staff protection and nuclear plants safety become more and more important. So techniques of pollutants simulation by specific tracers with the same aeraulic behaviour are an interesting tool in order to characterize their transfers. Resorting to aerosols tagged by a fluorescent dye allows to realize different studies in ventilation and filtration field. The feasibility of detection in real time for a particulate tracer is the main aim of this work. The need of such a technique is obvious because it can provide the specific aerosol behaviour. Furthermore, direct measurements in real time are required for model validation in calculation codes: they give the most realistic informations on interaction between contaminant and ventilation air flows. Up to now, the principle of fluorescent aerosol concentration measurement allows only an integral response in a delayed time, by means of sampling on filters and a fluorimetric analysis after a specific conditioning of these filters. In order to have the opportunity to detect in real time specific tracer, we have developed a new monitor able to count these particles on the following basis: fluorescent particles pass through a sampling nozzle up to a measurement chamber specially designed; sheath flow rate is defined to confine the test aerosol in the test aerosol in the sample flow rate at nozzle outlet; the interception of this stream by a highly focused laser beam allows aerosol detection and characterization particle by particle; the signature of a passing aerosol is the burst of photons that occurs when the fluoro-phore contained in the glycerol particle is excited by a light of adapted wavelength; these signals are transmitted to a photodetector by a patented optical arrangement. Then, an acquisition interfaced board connected to a computer, converts them into frequencies histograms. In the end, two kind of results could be provided simultaneously : the

A multi-parametric particle-pairing algorithm for particle tracking in single and multiphase flows

International Nuclear Information System (INIS)

Cardwell, Nicholas D; Vlachos, Pavlos P; Thole, Karen A

2011-01-01

Multiphase flows (MPFs) offer a rich area of fundamental study with many practical applications. Examples of such flows range from the ingestion of foreign particulates in gas turbines to transport of particles within the human body. Experimental investigation of MPFs, however, is challenging, and requires techniques that simultaneously resolve both the carrier and discrete phases present in the flowfield. This paper presents a new multi-parametric particle-pairing algorithm for particle tracking velocimetry (MP3-PTV) in MPFs. MP3-PTV improves upon previous particle tracking algorithms by employing a novel variable pair-matching algorithm which utilizes displacement preconditioning in combination with estimated particle size and intensity to more effectively and accurately match particle pairs between successive images. To improve the method's efficiency, a new particle identification and segmentation routine was also developed. Validation of the new method was initially performed on two artificial data sets: a traditional single-phase flow published by the Visualization Society of Japan (VSJ) and an in-house generated MPF data set having a bi-modal distribution of particles diameters. Metrics of the measurement yield, reliability and overall tracking efficiency were used for method comparison. On the VSJ data set, the newly presented segmentation routine delivered a twofold improvement in identifying particles when compared to other published methods. For the simulated MPF data set, measurement efficiency of the carrier phases improved from 9% to 41% for MP3-PTV as compared to a traditional hybrid PTV. When employed on experimental data of a gas–solid flow, the MP3-PTV effectively identified the two particle populations and reported a vector efficiency and velocity measurement error comparable to measurements for the single-phase flow images. Simultaneous measurement of the dispersed particle and the carrier flowfield velocities allowed for the calculation of

Observations of fluorescent aerosol-cloud interactions in the free troposphere at the Sphinx high Alpine research station, Jungfraujoch

Science.gov (United States)

Crawford, I.; Lloyd, G.; Bower, K. N.; Connolly, P. J.; Flynn, M. J.; Kaye, P. H.; Choularton, T. W.; Gallagher, M. W.

2015-09-01

The fluorescent nature of aerosol at a high Alpine site was studied using a wide-band integrated bioaerosol (WIBS-4) single particle multi-channel ultra violet-light induced fluorescence (UV-LIF) spectrometer. This was supported by comprehensive cloud microphysics and meteorological measurements with the aims of cataloguing concentrations of bio-fluorescent aerosols at this high altitude site and also investigating possible influences of UV-fluorescent particle types on cloud-aerosol processes. Analysis of background free tropospheric air masses, using a total aerosol inlet, showed there to be a minor but statistically insignificant increase in the fluorescent aerosol fraction during in-cloud cases compared to out of cloud cases. The size dependence of the fluorescent aerosol fraction showed the larger aerosol to be more likely to be fluorescent with 80 % of 10 μm particles being fluorescent. Whilst the fluorescent particles were in the minority (NFl/NAll = 0.27±0.19), a new hierarchical agglomerative cluster analysis approach, Crawford et al. (2015) revealed the majority of the fluorescent aerosol were likely to be representative of fluorescent mineral dust. A minor episodic contribution from a cluster likely to be representative of primary biological aerosol particles (PBAP) was also observed with a wintertime baseline concentration of 0.1±0.4 L-1. Given the low concentration of this cluster and the typically low ice active fraction of studied PBAP (e.g. pseudomonas syringae) we suggest that the contribution to the observed ice crystal concentration at this location is not significant during the wintertime.

The measurement of single particle temperature in plasma sprays

International Nuclear Information System (INIS)

Fincke, J.R.; Swank, W.D.; Bolsaitis, P.P.; Elliott, J.F.

1990-01-01

A measurement technique for simultaneously obtaining the size, velocity, temperature, and relative number density of particles entrained in high temperature flow fields is described. In determining the particle temperature from a two-color pyrometery technique, assumptions about the relative spectral emissivity of the particle are required. For situations in which the particle surface undergoes chemical reactions the assumption of grey body behavior is shown to introduce large Temperature measurement uncertainties. Results from isolated, laser heated, single particle measurements and in-flight data from the plasma spraying of WC-Co are presented. 10 refs., 5 figs

Single-Particle Tracking of Human Lipoproteins.

Science.gov (United States)

de Messieres, Michel; Ng, Abby; Duarte, Cornelio J; Remaley, Alan T; Lee, Jennifer C

2016-01-05

Lipoproteins, such as high-density lipoprotein (HDL), low-density lipoprotein (LDL), and very-low density lipoprotein (VLDL), play a critical role in heart disease. Lipoproteins vary in size and shape as well as in their apolipoprotein content. Here, we developed a new experimental framework to study freely diffusing lipoproteins from human blood, allowing analysis of even the smallest HDL with a radius of 5 nm. In an easily constructed confinement chamber, individual HDL, LDL, and VLDL particles labeled with three distinct fluorophores were simultaneously tracked by wide-field fluorescence microscopy and their sizes were determined by their motion. This technique enables studies of individual lipoproteins in solution and allows characterization of the heterogeneous properties of lipoproteins which affect their biological function but are difficult to discern in bulk studies.

Tagged particle in single-file diffusion with arbitrary initial conditions

Science.gov (United States)

Cividini, J.; Kundu, A.

2017-08-01

We compute the full probability distribution of the positions of a tagged particle exactly for the given arbitrary initial positions of the particles, and for general single-particle propagators. We consider the thermodynamic limit of our exact expressions in quenched and annealed settings. For a particular class of single-particle propagators, the exact formula is expressed in a simple integral form in the quenched case whereas in the annealed case, it is expressed as a simple combination of Bessel functions. In particular, we focus on the step and the power-law initial configurations. In the former case, a drift is induced even when the one-particle propagators are symmetric. On the other hand, in the later case the scaling of the cumulants of the position of the tracer differs from the uniform case. We provide numerical verifications of our results.

Tomograms and the quest for single particle nonlocality

International Nuclear Information System (INIS)

Anisimov, M A; Caponigro, M; Mancini, S; Man'ko, V I

2007-01-01

By using a tomographic approach to quantum states, we rise the problem of nonlocality within a single particle (single degree of freedom). We propose a possible way to look for such effects on a qubit. Although a conclusive answer is far from being reached, we provide some reflections on the foundational ground

Single-particle fusion of influenza viruses reveals complex interactions with target membranes

Science.gov (United States)

van der Borg, Guus; Braddock, Scarlett; Blijleven, Jelle S.; van Oijen, Antoine M.; Roos, Wouter H.

2018-05-01

The first step in infection of influenza A virus is contact with the host cell membrane, with which it later fuses. The composition of the target bilayer exerts a complex influence on both fusion efficiency and time. Here, an in vitro, single-particle approach is used to study this effect. Using total internal reflection fluorescence (TIRF) microscopy and a microfluidic flow cell, the hemifusion of single virions is visualized. Hemifusion efficiency and kinetics are studied while altering target bilayer cholesterol content and sialic-acid donor. Cholesterol ratios tested were 0%, 10%, 20%, and 40%. Sialic-acid donors GD1a and GYPA were used. Both cholesterol ratio and sialic-acid donors proved to have a significant effect on hemifusion efficiency. Furthermore, comparison between GD1a and GYPA conditions shows that the cholesterol dependence of the hemifusion time is severely affected by the sialic-acid donor. Only GD1a shows a clear increasing trend in hemifusion efficiency and time with increasing cholesterol concentration of the target bilayer with maximum rates for GD1A and 40% cholesterol. Overall our results show that sialic acid donor and target bilayer composition should be carefully chosen, depending on the desired hemifusion time and efficiency in the experiment.

Fano Description of Single-Hydrocarbon Fluorescence Excited by a Scanning Tunneling Microscope.

Science.gov (United States)

Kröger, Jörg; Doppagne, Benjamin; Scheurer, Fabrice; Schull, Guillaume

2018-06-13

The detection of fluorescence with submolecular resolution enables the exploration of spatially varying photon yields and vibronic properties at the single-molecule level. By placing individual polycyclic aromatic hydrocarbon molecules into the plasmon cavity formed by the tip of a scanning tunneling microscope and a NaCl-covered Ag(111) surface, molecular light emission spectra are obtained that unravel vibrational progression. In addition, light spectra unveil a signature of the molecule even when the tunneling current is injected well separated from the molecular emitter. This signature exhibits a distance-dependent Fano profile that reflects the subtle interplay between inelastic tunneling electrons, the molecular exciton and localized plasmons in at-distance as well as on-molecule fluorescence. The presented findings open the path to luminescence of a different class of molecules than investigated before and contribute to the understanding of single-molecule luminescence at surfaces in a unified picture.

Single-particle motion in rapidly rotating nuclei

International Nuclear Information System (INIS)

Bengtsson, R.; Frisk, H.

1985-01-01

The motion of particles belonging to a single-j shell is described in terms of classical orbitals. The effects of rapid rotation and pairing correlations are discussed and the results are compared with the quantum mechanical orbitals. (orig.)

Damping of unbound single-particle modes

International Nuclear Information System (INIS)

Fortier, S.; Beaumel, D.; Gales, S.; Guillot, J.; Langevin-Joliot, H.; Laurent, H.; Maison, J.M.

1995-07-01

The (α, 3 He-n) reaction has been investigated at 120 MeV incident energy on 64 Ni, 90 Zr and 120 Sn target nuclei. Neutrons in coincidence with 3 He particles emitted at 0 deg were detected, in order to get information about the decay of single-particle states embedded in the (α, 3 He) continuum. Neutron angular correlations, multiplicity values and branching ratios to low-lying states of the final nuclei have been compared with the predictions of the statistical decay model. Direct branching ratios in 91 Zr deduced from this analysis are compared with the predictions of two nuclear structure models. (author)

Detection of ultra-high energy cosmic ray showers with a single-pixel fluorescence telescope

Czech Academy of Sciences Publication Activity Database

Fujii, T.; Malacari, M.; Bertaina, M.; Casolino, E.; Dawson, B.; Horváth, P.; Hrabovský, M.; Jiang, J.; Mandát, Dušan; Matalon, A.; Matthews, J.N.; Motloch, P.; Palatka, Miroslav; Pech, Miroslav; Privitera, P.; Schovánek, Petr; Takizawa, Y.; Thomas, S.B.; Trávníček, Petr; Yamazaki, K.

2016-01-01

Roč. 74, Feb (2016), s. 64-72 ISSN 0927-6505 R&D Projects: GA MŠk(CZ) LG13007 Institutional support: RVO:68378271 Keywords : ultra-high energy cosmic rays * fluorescence detector * extensive air shower Subject RIV: BF - Elementary Particles and High Energy Physics Impact factor: 3.257, year: 2016

Vascular thrombus imaging in vivo via near-infrared fluorescent nanodiamond particles bioengineered with the disintegrin bitistatin (Part II

Directory of Open Access Journals (Sweden)

Gerstenhaber JA

2017-11-01

Full Text Available Jonathan A Gerstenhaber,1,* Frank C Barone,2,* Cezary Marcinkiewicz,1,3 Jie Li,2 Aaron O Shiloh,4 Mark Sternberg,3 Peter I Lelkes,1,* Giora Feuerstein1,3,* 1Department of Bioengineering, College of Engineering, Temple University, Philadelphia, PA, 2Department of Neurology, State University of New York Downstate Medical Center, Brooklyn, NY, 3Debina Diagnostic Inc., Newtown Square, 4Diagnostic Imaging, Inc., Philadelphia, PA, USA *These authors contributed equally to this work Abstract: The aim of this feasibility study was to test the ability of fluorescent nanodiamond particles (F-NDP covalently conjugated with bitistatin (F-NDP-Bit to detect vascular blood clots in vivo using extracorporeal near-infrared (NIR imaging. Specifically, we compared NIR fluorescence properties of F-NDP with N-V (F-NDPNV and N-V-N color centers and sizes (100–10,000 nm. Optimal NIR fluorescence and tissue penetration across biological tissues (rat skin, porcine axillary veins, and skin was obtained for F-NDPNV with a mean diameter of 700 nm. Intravital imaging (using in vivo imaging system [IVIS] in vitro revealed that F-NDPNV-loaded glass capillaries could be detected across 6 mm of rat red-muscle barrier and 12 mm of porcine skin, which equals the average vertical distance of a human carotid artery bifurcation from the surface of the adjacent skin (14 mm. In vivo, feasibility was demonstrated in a rat model of occlusive blood clots generated using FeCl3 in the carotid artery bifurcation. Following systemic infusions of F-NDPNV-Bit (3 or 15 mg/kg via the external carotid artery or femoral vein (N=3, presence of the particles in the thrombi was confirmed both in situ via IVIS, and ex vivo via confocal imaging. The presence of F-NDPNV in the vascular clots was further confirmed by direct counting of fluorescent particles extracted from clots following tissue solubilization. Our data suggest that F-NDPNV-Bit associate with vascular blood clots, presumably by binding

Strong reduction of spectral heterogeneity in gold bipyramids for single-particle and single-molecule plasmon sensing.

Science.gov (United States)

Peters, S M E; Verheijen, M A; Prins, M W J; Zijlstra, P

2016-01-15

Single metal nanoparticles are attractive biomolecular sensors. Binding of analyte to a functional particle results in a plasmon shift that can be conveniently monitored in a far-field optical microscope. Heterogeneities in spectral properties of individual particles in an ensemble affect the reliability of a single-particle plasmon sensor, especially when plasmon shifts are monitored in real-time using a fixed irradiation wavelength. We compare the spectral heterogeneity of different plasmon sensor geometries (gold nanospheres, nanorods, and bipyramids) and correlate this to their size and aspect-ratio dispersion. We show that gold bipyramids exhibit a strongly reduced heterogeneity in aspect ratio and plasmon wavelength compared to commonly used gold nanorods. We show that this translates into a significantly improved homogeneity of the response to molecular binding without compromising single-molecule sensitivity.

Physical and chemical study of single aerosol particles using optical trapping cavity ringdown spectroscopy

Science.gov (United States)

2016-08-30

scope that views the trapped particle walking through the ringdown beam step by step. (b) An image that shows the traces of the particle (MWCNT... walking through the RD beam . 5 a b c Fig.3 The OT-CRDS single particle scope views oscillations of a trapped particle. (a) Image of a trapped...and walking single carbon- nanotube particles of ?50 µm in size and viewing those properties via changes of ringdown time. This single- aerosol

New instrument for tribocharge measurement due to single particle impacts

International Nuclear Information System (INIS)

Watanabe, Hideo; Ghadiri, Mojtaba; Matsuyama, Tatsushi; Ding Yulong; Pitt, Kendal G.

2007-01-01

During particulate solid processing, particle-particle and particle-wall collisions can generate electrostatic charges. This may lead to a variety of problems ranging from fire and explosion hazards to segregation, caking, and blocking. A fundamental understanding of the particle charging in such situations is therefore essential. For this purpose we have developed a new device that can measure charge transfer due to impact between a single particle and a metal plate. The device consists of an impact test system and two sets of Faraday cage and preamplifier for charge measurement. With current amplifiers, high-resolution measurements of particle charges of approximately 1 and 10 fC have been achieved before and after the impact, respectively. The device allows charge measurements of single particles with a size as small as ∼100 μm impacting on the target at different incident angles with a velocity up to about 80 m/s. Further analyses of the charge transfer as a function of particle initial charge define an equilibrium charge, i.e., an initial charge level prior to impact for which no net charge transfer would occur as a result of impact

A Nanofluidic Mixing Device for High-throughput Fluorescence Sensing of Single Molecules

NARCIS (Netherlands)

Mathwig, Klaus; Fijen, C.; Fontana, M.; Lemay, S.G.; Hohlbein, J.C.

2017-01-01

We introduce a nanofluidic mixing device entirely fabricated in glass for the fluorescence detection of single molecules. The design consists of a nanochannel T-junction and allows the continuous monitoring of chemical or enzymatic reactions of analytes as they arrive from two independent inlets.

Subunits of highly Fluorescent Protein R-Phycoerythrin as Probes for Cell Imaging and Single-Molecule Detection

Energy Technology Data Exchange (ETDEWEB)

Isailovic, Dragan [Iowa State Univ., Ames, IA (United States)

2005-01-01

The purposes of our research were: (1) To characterize subunits of highly fluorescent protein R-Phycoerythrin (R-PE) and check their suitability for single-molecule detection (SMD) and cell imaging, (2) To extend the use of R-PE subunits through design of similar proteins that will be used as probes for microscopy and spectral imaging in a single cell, and (3) To demonstrate a high-throughput spectral imaging method that will rival spectral flow cytometry in the analysis of individual cells. We first demonstrated that R-PE subunits have spectroscopic and structural characteristics that make them suitable for SMD. Subunits were isolated from R-PE by high-performance liquid chromatography (HPLC) and detected as single molecules by total internal reflection fluorescence microscopy (TIRFM). In addition, R-PE subunits and their enzymatic digests were characterized by several separation and detection methods including HPLC, capillary electrophoresis, sodium dodecyl sulfate-polyacrilamide gel electrophoresis (SDS-PAGE) and HPLC-electrospray ionization mass spectrometry (ESI-MS). Favorable absorption and fluorescence of the R-PE subunits and digest peptides originate from phycoerythrobilin (PEB) and phycourobilin (PUB) chromophores that are covalently attached to cysteine residues. High absorption coefficients and strong fluorescence (even under denaturing conditions), broad excitation and emission fluorescence spectra in the visible region of electromagnetic spectrum, and relatively low molecular weights make these molecules suitable for use as fluorescence labels of biomolecules and cells. We further designed fluorescent proteins both in vitro and in vivo (in Escherichia coli) based on the highly specific attachment of PEB chromophore to genetically expressed apo-subunits of R-PE. In one example, apo-alpha and apo-beta R-PE subunits were cloned from red algae Polisiphonia boldii (P. boldii), and expressed in E. coli. Although expressed apo-subunits formed inclusion

Three-dimensional single-particle tracking in live cells: news from the third dimension

International Nuclear Information System (INIS)

Dupont, A; Wehnekamp, F; Katayama, Y; Lamb, D C; Gorelashvili, M; Schüller, V; Arcizet, D; Heinrich, D

2013-01-01

Single-particle tracking (SPT) is of growing importance in the biophysical community. It is used to investigate processes such as drug and gene delivery, viral uptake, intracellular trafficking or membrane-bound protein mobility. Traditionally, SPT is performed in two dimensions (2D) because of its technical simplicity. However, life occurs in three dimensions (3D) and many methods have been recently developed to track particles in 3D. Now, is the third dimension worth the effort? Here we investigate the differences between the 2D and 3D analyses of intracellular transport with the 3D development of a time-resolved mean square displacement (MSD) analysis introduced previously. The 3D trajectories, and the 2D projections, of fluorescent nanoparticles were obtained with an orbital tracking microscope in two different cell types: in Dictyostelium discoideum ameba and in adherent, more flattened HuH-7 human cells. As expected from the different 3D organization of both cells’ cytoskeletons, a third of the active transport was lost upon projection in the ameba whereas the identification of the active phases was barely affected in the HuH-7 cells. In both cell types, we found intracellular diffusion to be anisotropic and the diffusion coefficient values derived from the 2D analysis were therefore biased. (paper)

Influence of Torrefaction on Single Particle Combustion of Wood

DEFF Research Database (Denmark)

Lu, Zhimin; Jian, Jie; Jensen, Peter Arendt

2016-01-01

This study focuses on the influence of torrefaction on the char reactivity, char yield, and combustion time of 3-5 mm spherical wood particles in a single particle combustion reactor (SPC) operating at a nominal temperature of 1231 °C. The devolatilization times were reduced and the char burnout...

Pairing fluctuation effects on the single-particle spectra for the superconducting state

International Nuclear Information System (INIS)

Pieri, P.; Pisani, L.; Strinati, G.C.

2004-01-01

Single-particle spectra are calculated in the superconducting state for a fermionic system with an attractive interaction, as functions of temperature and coupling strength from weak to strong. The fermionic system is described by a single-particle self-energy that includes pairing-fluctuation effects in the superconducting state. The theory reduces to the ordinary BCS approximation in weak coupling and to the Bogoliubov approximation for the composite bosons in strong coupling. Several features of the single-particle spectral function are shown to compare favorably with experimental data for cuprate superconductors

A transient single particle model under FCI conditions

Institute of Scientific and Technical Information of China (English)

LI Xiao-Yan; SHANG Zhi; XU Ji-Jun

2005-01-01

The paper is focused on the coupling effect between film boiling heat transfer and evaporation drag around a hot-particle in cold liquid. Based on the continuity, momentum and energy equations of the vapor film, a transient two-dimensional single particle model has been established. This paper contains a detailed description of HPMC (High-temperature Particle Moving in Coolant) model for studying some aspects of the premixing stage of fuel-coolant interactions (FCIs). The transient process of high-temperature particles moving in coolant can be simulated. Comparisons between the experiment results and the calculations using HPMC model demonstrate that HPMC model achieves a good agreement in predicting the time-varying characteristic of high-temperature spheres moving in coolant.

Optimization of magnetic switches for single particle and cell transport

Energy Technology Data Exchange (ETDEWEB)

Abedini-Nassab, Roozbeh; Yellen, Benjamin B., E-mail: yellen@duke.edu [Department of Mechanical Engineering and Materials Science, Duke University, Box 90300 Hudson Hall, Durham, North Carolina 27708 (United States); Joint Institute, University of Michigan—Shanghai Jiao Tong University, Shanghai Jiao Tong University, Shanghai 200240 (China); Murdoch, David M. [Department of Medicine, Duke University, Durham, North Carolina 27708 (United States); Kim, CheolGi [Department of Emerging Materials Science, Daegu Gyeongbuk Institute of Science and Technology (DGIST), Daegu 711-873 (Korea, Republic of)

2014-06-28

The ability to manipulate an ensemble of single particles and cells is a key aim of lab-on-a-chip research; however, the control mechanisms must be optimized for minimal power consumption to enable future large-scale implementation. Recently, we demonstrated a matter transport platform, which uses overlaid patterns of magnetic films and metallic current lines to control magnetic particles and magnetic-nanoparticle-labeled cells; however, we have made no prior attempts to optimize the device geometry and power consumption. Here, we provide an optimization analysis of particle-switching devices based on stochastic variation in the particle's size and magnetic content. These results are immediately applicable to the design of robust, multiplexed platforms capable of transporting, sorting, and storing single cells in large arrays with low power and high efficiency.

Emissions from Ethanol-Gasoline Blends: A Single Particle Perspective

Directory of Open Access Journals (Sweden)

Peter H. McMurry

2011-06-01

Full Text Available Due to its agricultural origin and function as a fuel oxygenate, ethanol is being promoted as an alternative biomass-based fuel for use in spark ignition engines, with mandates for its use at state and regional levels. While it has been established that the addition of ethanol to a fuel reduces the particulate mass concentration in the exhaust, little attention has been paid to changes in the physicochemical properties of the emitted particles. In this work, a dynamometer-mounted GM Quad-4 spark ignition engine run without aftertreatment at 1,500 RPM and 100% load was used with four different fuel blends, containing 0, 20, 40 and 85 percent ethanol in gasoline. This allowed the effects of the fuel composition to be isolated from other effects. Instrumentation employed included two Aerosol Time-of-Flight Mass Spectrometers covering different size ranges for analysis of single particle composition, an Aethalometer for black carbon, a Scanning Mobility Particle Sizer for particle size distributions, a Photoelectric Aerosol Sensor for particle-bound polycyclic aromatic hydrocarbon (PAH species and gravimetric filter measurements for particulate mass concentrations. It was found that, under the conditions investigated here, additional ethanol content in the fuel changes the particle size distribution, especially in the accumulation mode, and decreases the black carbon and total particulate mass concentrations. The molecular weight distribution of the PAHs was found to decrease with added ethanol. However, PAHs produced from higher ethanol-content fuels are associated with NO2− (m/z—46 in the single-particle mass spectra, indicating the presence of nitro-PAHs. Compounds associated with the gasoline (e.g., sulfur-containing species are diminished due to dilution as ethanol is added to the fuel relative to those associated with the lubricating oil (e.g., calcium, zinc, phosphate in the single particle spectra. These changes have potential

Studies of the neutron single-particle structure of exotic nuclei at the HRIBF

International Nuclear Information System (INIS)

Thomas, J.S.; Bardayan, D.W.; Blackmon, J.C.; Cizewski, J.A.; Greife, U.; Gross, C.J.; Johnson, M.S.; Jones, K.L.; Kozub, R.L.; Liang, J.F.; Livesay, R.J.; Ma, Z.; Moazen, B.H.; Nesaraja, C.D.; Shapira, D.; Smith, M.S.

2004-01-01

The study of neutron single-particle strengths in neutron-rich nuclei is of interest for nuclear structure and nuclear astrophysics. The distribution of single-particle strengths constrains the effective Hamiltonian and pairing interactions and determines neutron interaction rates that are crucial for understanding the synthesis of heavy nuclei in supernovae via the rapid neutron capture process. Particularly important are the neutron single-particle levels in nuclei near closed neutron shells. Radioactive ion beams from the Holifield Radioactive Ion Beam Facility have been used to study (d,p) reactions in inverse kinematics in order to probe neutron single-particle states in exotic nuclei. The results of a measurement with a 82 Ge beam will be presented

Synthesis and characterization of bioresorbable calcium phosphosilicate nanocomposite particles for fluorescence imaging and biomedical applications

Science.gov (United States)

Morgan, Thomas T.

Organically doped calcium phosphosilicate nanoparticles (CPSNPs) were developed and characterized, driven by the need for non-toxic vectors for drug delivery and fluorescence biological imaging applications. In particular, advancement in drug delivery for the chemotherapeutic treatment of cancers is required to increase drug efficacy and improve patient quality of life. Additionally, brighter and more photostable fluorophores are needed to meet demands for improved sensitivity and experimental diversity, which may lead to improvements in early detection of solid tumors and advancement in understanding of biological processes. A literature survey on the state of the field for nanoparticle based biological fluorescence imaging and drug delivery is presented in Chapter 1. Chapter 2 focuses on the characterization techniques used in this work. The development and optical characterization of 20-40 nm diameter, citrate functionalized Cy3 amidite doped calcium phosphosilicate nanoparticles (Cy3 CPSNPs) for in vitro fluorescence imaging is outlined in Chapters 3 and 4, respectively. In particular, sodium citrate was used to functionalize the surface and provide electrosteric dispersion of these particles. CPSNPs stabilized with sodium citrate routinely exhibited highly negative zeta potentials greater than -25 mV in magnitude. Furthermore, the fluorescence quantum yield of the encapsulated fluorophore was improved by more than 4.5-fold when compared to the unencapsulated dye. The bioimaging and drug delivery capability of CPSNPs was explored. Cy3 CPSNPs dissolved quickly in the acidic environment experienced during endocytosis, releasing the encapsulated fluorophore. This is consistent with solution phase experiments that show the particles are dissolved at pH 5. CPSNPs loaded with fluorescein and a hydrophobic growth inhibitor, ceramide C6, proved the ability to simultaneously image and delivery of the hydrophobic drug to cells in vitro. Chapter 5 examined the colloidal

Developing DNA nanotechnology using single-molecule fluorescence.

Science.gov (United States)

Tsukanov, Roman; Tomov, Toma E; Liber, Miran; Berger, Yaron; Nir, Eyal

2014-06-17

CONSPECTUS: An important effort in the DNA nanotechnology field is focused on the rational design and manufacture of molecular structures and dynamic devices made of DNA. As is the case for other technologies that deal with manipulation of matter, rational development requires high quality and informative feedback on the building blocks and final products. For DNA nanotechnology such feedback is typically provided by gel electrophoresis, atomic force microscopy (AFM), and transmission electron microscopy (TEM). These analytical tools provide excellent structural information; however, usually they do not provide high-resolution dynamic information. For the development of DNA-made dynamic devices such as machines, motors, robots, and computers this constitutes a major problem. Bulk-fluorescence techniques are capable of providing dynamic information, but because only ensemble averaged information is obtained, the technique may not adequately describe the dynamics in the context of complex DNA devices. The single-molecule fluorescence (SMF) technique offers a unique combination of capabilities that make it an excellent tool for guiding the development of DNA-made devices. The technique has been increasingly used in DNA nanotechnology, especially for the analysis of structure, dynamics, integrity, and operation of DNA-made devices; however, its capabilities are not yet sufficiently familiar to the community. The purpose of this Account is to demonstrate how different SMF tools can be utilized for the development of DNA devices and for structural dynamic investigation of biomolecules in general and DNA molecules in particular. Single-molecule diffusion-based Förster resonance energy transfer and alternating laser excitation (sm-FRET/ALEX) and immobilization-based total internal reflection fluorescence (TIRF) techniques are briefly described and demonstrated. To illustrate the many applications of SMF to DNA nanotechnology, examples of SMF studies of DNA hairpins and

Novel method for noncontact measurement of particle temperatures

NARCIS (Netherlands)

Wagenaar, B.M.; Meijer, R.; Kuipers, J.A.M.; van Swaaij, W.P.M.

1995-01-01

A nonintrusive temperature measurement technique is developed for noncontact measurement of the temperature of single particles with <200 µm dia. It is based on the temperature dependence of the fluorescence spectrum resulting from irradiation of a certain phosphor mixture with UV light by applying

Novel method for noncontact measurement of particle temperatures

NARCIS (Netherlands)

Wagenaar, B.M.; Wagenaar, B.M.; Meijer, R.; Kuipers, J.A.M.; van Swaaij, Willibrordus Petrus Maria

1995-01-01

A nonintrusive temperature measurement technique is developed for noncontact measurement of the temperature of single particles with < 200 m dia. It is based on the temperature dependence of the fluorescence spectrum resulting from irradiation of a certain phosphor mixture with UV light by applying

DNA Three-Way Junction for Differentiation of Single-Nucleotide Polymorphisms with Fluorescent Copper Nanoparticles.

Science.gov (United States)

Sun, Feifei; You, Ying; Liu, Jie; Song, Quanwei; Shen, Xiaotong; Na, Na; Ouyang, Jin

2017-05-23

A label- and enzyme-free fluorescent sensor for the detection of single-nucleotide polymorphisms (SNPs) at room temperature is proposed, using new copper nanoparticles (CuNPs) as fluorescent reporters. The CuNPs were constructed by using a DNA three-way junction (3WJ) template. In this assay, two complementary adenine/thymine-rich probes can hybridize with the wild-type target simultaneously to construct a 3WJ structure, serving as an efficient scaffold for the generation of CuNPs. However, the CuNPs produce weak fluorescence when the probes bind with a mutant-type target. SNPs can be identified by the difference in fluorescence intensity of the CuNPs. This SNPs detection strategy is straightforward, cost-effective, and avoids the complicated procedures of labeling or enzymatic reactions. The fluorescent sensor is versatile and can be applied to all types of mutation because the probes are programmable. Moreover, the sensor exhibits good detection performance in biological samples. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

Autofluorescence of atmospheric bioaerosols – fluorescent biomolecules and potential interferences

Directory of Open Access Journals (Sweden)

C. Pöhlker

2012-01-01

supermicron particle fluorescence in wavelength ranges used for most FBAP instruments is likely to be dominated by biological material and that such instrumentation is able to discriminate between FBAP and non-biological material in many situations. More detailed follow-up studies on single particle fluorescence are still required to reduce these uncertainties further, however.

Single-particle behaviour in circulating fluidized beds

DEFF Research Database (Denmark)

Erik Weinell, Claus; Dam-Johansen, Kim; Johnsson, Jan Erik

1997-01-01

This paper describes an experimental investigation of single-particle behaviour in a cold pilot-scale model of a circulating fluidized bed combustor (CFBC). In the system, sand is recirculated by means of air. Pressure measurements along the riser are used to determine the suspension density...

Prospects of real-time single-particle biological aerosol analysis: A comparison between laser-induced breakdown spectroscopy and aerosol time-of-flight mass spectrometry

International Nuclear Information System (INIS)

Beddows, D.C.S.; Telle, H.H.

2005-01-01

In this paper we discuss the prospects of real-time, in situ laser-induced breakdown spectroscopy applied for the identification and classification of bio-aerosols (including species of potential bio-hazard) within common urban aerosol mixtures. In particular, we address the issues associated with the picking out of bio-aerosols against common background aerosol particles, comparing laser-induced breakdown spectroscopy measurements with data from a mobile single-particle aerosol mass spectrometer (ATOFMS). The data from the latter provide statistical data over an extended period of time, highlighting the variation of the background composition. While single-particle bio-aerosols are detectable in principle, potential problems with small (∼ 1 μm size) bio-aerosols have been identified; constituents of the air mass other than background aerosols, e.g. gaseous CO 2 in conjunction with common background aerosols, may prevent unique recognition of the bio-particles. We discuss whether it is likely that laser-induced breakdown spectroscopy on its own can provide reliable, real-time identification of bio-aerosol in an urban environment, and it is suggested that more than one technique should be or would have to be used. A case for using a combination of laser-induced breakdown spectroscopy and Raman (and/or) laser-induced fluorescence spectroscopy is made

Electrostatic deposition of a micro solder particle using a single probe by applying a single rectangular pulse

International Nuclear Information System (INIS)

Nakabayashi, Daizo; Sawai, Kenji; Saito, Shigeki; Takahashi, Kunio

2012-01-01

Recently, micromanipulation techniques have been in high demand. A technique to deposit a metal microparticle onto a metal substrate by using a single metal probe has been proposed as one of the techniques. A solder particle with a diameter of 20–30 µm, initially adhering to the probe tip, is detached and deposited onto a substrate. The success rate of the particle deposition was 44% in the previous research, and is insufficient for industrial applications. In this paper, a technique of particle deposition by applying a single rectangular pulse is proposed, and the mechanism of the deposition is described. In the mechanism, an electric discharge between the probe and the particle when the particle reaches the substrate plays an important role in the particle deposition. Moreover, the mechanism of the proposed technique is verified by experiments of particle deposition, which are observed using a high-speed camera, a scanning electron microscope (SEM) and an oscilloscope. The success rate of the particle deposition has increased to 93% by the proposed technique. Furthermore, the damage to the particle by the electric discharge is evaluated using an RC circuit model, and the applicability of the proposed technique is discussed. (paper)

Fluorescence spectral fluctuations of single LH2 complexes from Rhodopseudomonas acidophila strain 10050

NARCIS (Netherlands)

Rutkauskas, D.; Novoderezkhin, V.; Cogdell, R.J.; van Grondelle, R.

2004-01-01

We have investigated the energy landscape of the bacterial photosynthetic peripheral light-harvesting complex LH2 of purple bacterium Rhodopseudomonas acidophila by monitoring sequences of fluorescence spectra of single LH2 assemblies, at room temperature, with different excitation intensities as

Single-Particle Discrimination of Retroviruses from Extracellular Vesicles by Nanoscale Flow Cytometry.

Science.gov (United States)

Tang, Vera A; Renner, Tyler M; Fritzsche, Anna K; Burger, Dylan; Langlois, Marc-André

2017-12-19

Retroviruses and small EVs overlap in size, buoyant densities, refractive indices and share many cell-derived surface markers making them virtually indistinguishable by standard biochemical methods. This poses a significant challenge when purifying retroviruses for downstream analyses or for phenotypic characterization studies of markers on individual virions given that EVs are a major contaminant of retroviral preparations. Nanoscale flow cytometry (NFC), also called flow virometry, is an adaptation of flow cytometry technology for the analysis of individual nanoparticles such as extracellular vesicles (EVs) and retroviruses. In this study we systematically optimized NFC parameters for the detection of retroviral particles in the range of 115-130 nm, including viral production, sample labeling, laser power and voltage settings. By using the retroviral envelope glycoprotein as a selection marker, and evaluating a number of fluorescent dyes and labeling methods, we demonstrate that it is possible to confidently distinguish retroviruses from small EVs by NFC. Our findings make it now possible to individually phenotype genetically modified retroviral particles that express a fluorescent envelope glycoprotein without removing EV contaminants from the sample.

Single particle train ordering in microchannel based on inertial and vortex effects

Science.gov (United States)

Fan, Liang-Liang; Yan, Qing; Zhe, Jiang; Zhao, Liang

2018-06-01

A new microfluidic device for microparticle focusing and ordering in a single particle train is reported. The particle focusing and ordering are based on inertial and vortex effects in a microchannel with a series of suddenly contracted and widely expanded structures on one side. In the suddenly contracted regions, particles located near the contracted structures are subjected to a strong wall-effect lift force and momentum-change-induced inertial force due to the highly curved trajectory, migrating to the straight wall. A horizontal vortex is generated downstream of the contracted structure, which prevents the particle from getting close to the wall. In the widely expanded regions, the streamline is curved and no vortex is generated. The shear-gradient lift force and the momentum-change-induced inertial force are dominant for particle lateral migration, driving particles towards the wall of the expanded structures. Eventually, particles are focused and ordered in a single particle train by the combination effects of the inertial forces and the vortex. In comparison with other single-stream particle focusing methods, this device requires no sheath flow, is easy for fabrication and operation, and can work over a wide range of Reynolds numbers from 19.1–142.9. The highly ordered particle chain could be potentially utilized in a variety of lab-chip applications, including micro-flow cytometer, imaging and droplet-based cell entrapment.

Single-particle energies and density of states in density functional theory

Science.gov (United States)

van Aggelen, H.; Chan, G. K.-L.

2015-07-01

Time-dependent density functional theory (TD-DFT) is commonly used as the foundation to obtain neutral excited states and transition weights in DFT, but does not allow direct access to density of states and single-particle energies, i.e. ionisation energies and electron affinities. Here we show that by extending TD-DFT to a superfluid formulation, which involves operators that break particle-number symmetry, we can obtain the density of states and single-particle energies from the poles of an appropriate superfluid response function. The standard Kohn- Sham eigenvalues emerge as the adiabatic limit of the superfluid response under the assumption that the exchange- correlation functional has no dependence on the superfluid density. The Kohn- Sham eigenvalues can thus be interpreted as approximations to the ionisation energies and electron affinities. Beyond this approximation, the formalism provides an incentive for creating a new class of density functionals specifically targeted at accurate single-particle eigenvalues and bandgaps.

The fluorescence properties of aerosol larger than 0.8 μm in an urban and a PBA-dominated location

Science.gov (United States)

Gabey, A. M.; Stanley, W. R.; Gallagher, M. W.; Kaye, P. H.

2011-01-01

Dual-wavelength Ultraviolet light-induced fluorescence (UV-LIF) measurements were performed on ambient environmental aerosol in Manchester, UK (urban city centre, winter) and Borneo, Malaysia (remote, tropical), which are taken to represent environments with negligible and significant primary biological aerosol (PBA) influences, respectively. Single-particle fluorescence intensity and optical equivalent diameter were measured with a Wide Issue Bioaerosol Sensor, version 3 (WIBS3) in the diameter range 0.8 μm≤DP≤20 μm for 2-3 weeks and filters were analysed using energy dispersive X-ray (EDX) spectroscopy, which revealed mostly non-PBA dominated particle sizes larger than 1 μm in Manchester. The WIBS3 features three fluorescence channels: Fluorescence excited at 280 nm is recorded at 310-400 nm and 400-600 nm and fluorescence excited at 370 nm is detected at 400-600 nm. In Manchester the primary size mode of fluorescent and non-fluorescent material was at 1.2 μm. In Borneo non-fluorescent material peaked at 1.2 μm and fluorescent at 3-4 μm. The fluorescence intensity at 400-600 nm generally increased with DP at both sites, as did the 310-400 nm intensity in Borneo. In Manchester the 310-400 m fluorescence decreased at DP>4 μm, suggesting this channel offers additional discrimination between fluorescent particle types. Finally, the ratio of fluorescence intensity in two pairs of channels was investigated as a function of particle diameter and this varied significantly between the two environments, demonstrating that the fluorescent aerosol in each can in principle be distinguished using a combination of fluorescence and elastic scattering measurements.

Statistical Methods for Single-Particle Electron Cryomicroscopy

DEFF Research Database (Denmark)

Jensen, Katrine Hommelhoff

Electron cryomicroscopy (cryo-EM) is a form of transmission electron microscopy, aimed at reconstructing the 3D structure of a macromolecular complex from a large set of 2D projection images, as they exhibit a very low signal-to-noise ratio (SNR). In the single-particle reconstruction (SPR) probl...

Single Molecule 3D Orientation in Time and Space: A 6D Dynamic Study on Fluorescently Labeled Lipid Membranes

DEFF Research Database (Denmark)

Börner, Richard; Ehrlich, Nicky; Hohlbein, Johannes

2016-01-01

Interactions between single molecules profoundly depend on their mutual three-dimensional orientation. Recently, we demonstrated a technique that allows for orientation determination of single dipole emitters using a polarization-resolved distribution of fluorescence into several detection channels...... interesting in non-isotropic environments such as lipid membranes, which are of great importance in biology. We used giant unilamellar vesicles (GUVs) labeled with fluorescent dyes down to a single molecule concentration as a model system for both, assessing the robustness of the orientation determination...

Fluorescent S-layer fusion proteins

International Nuclear Information System (INIS)

Kainz, B.

2010-01-01

This work describes the construction and characterisation of fluorescent S-layer fusion proteins used as building blocks for the fabrication of nanostructured monomolecular biocoatings on silica particles with defined fluorescence properties. The S-layer protein SgsE of Geobacillus stearothermophilus NRS 2004/3a was fused with the pH-dependant cyan, green and yellow variant of the green fluorescent protein (GFP) and the red fluorescent protein mRFP1. These fluorescent S-layer fusion proteins, acting as scaffold and optical sensing element simultaneously, were able to reassemble in solution and on silica particles forming 2D nanostructures with p2 lattice symmetry (a=11 ±0.5 nm, b=14 ±0.4 nm, g=80 ±1 o ). The pH-dependant fluorescence behaviour was studied with fluorimetry, confocal microscopy and flow cytometry. These fluorescent S-layer fusion proteins can be used as pH-sensor. 50% of the fluorescence intensity decreases at their calculated pKa values (pH6 - pH5). The fluorescence intensity of the GFP variants vanished completely between pH4 and pH3 whereas the chromophore of the red protein mRFP1 was only slightly affected in acidic conditions. At the isoelectric point of the S-layer coated silica particles (pH4.6 ±0.2) an increase in particle aggregation was detected by flow cytometry. The cyan and yellow fluorescent proteins were chosen to create a bi-fluorescent S-layer tandem fusion protein with the possibility for resonance energy transfer (FRET). A transfer efficiency of 20% and a molecular distance between the donor (ECFP) and acceptor (YFP) chromophores of around 6.2 nm could be shown. This bi-fluorescent ECFP-SgsE-YFP tandem fusion protein was able to reassemble on solid surfaces. The remarkable combination of fluorescence and self-assembly and the design of bi-functional S-layer tandem fusion protein matrices makes them to a promising tool in nanobiotechnology. (author) [de

Single photon counting fluorescence lifetime detection of pericellular oxygen concentrations.

Science.gov (United States)

Hosny, Neveen A; Lee, David A; Knight, Martin M

2012-01-01

Fluorescence lifetime imaging microscopy offers a non-invasive method for quantifying local oxygen concentrations. However, existing methods are either invasive, require custom-made systems, or show limited spatial resolution. Therefore, these methods are unsuitable for investigation of pericellular oxygen concentrations. This study describes an adaptation of commercially available equipment which has been optimized for quantitative extracellular oxygen detection with high lifetime accuracy and spatial resolution while avoiding systematic photon pile-up. The oxygen sensitive fluorescent dye, tris(2,2'-bipyridyl)ruthenium(II) chloride hexahydrate [Ru(bipy)(3)](2+), was excited using a two-photon excitation laser. Lifetime was measured using a Becker & Hickl time-correlated single photon counting, which will be referred to as a TCSPC card. [Ru(bipy)(3)](2+) characterization studies quantified the influences of temperature, pH, cellular culture media and oxygen on the fluorescence lifetime measurements. This provided a precisely calibrated and accurate system for quantification of pericellular oxygen concentration based on measured lifetimes. Using this technique, quantification of oxygen concentrations around isolated viable chondrocytes, seeded in three-dimensional agarose gel, revealed a subpopulation of cells that exhibited significant spatial oxygen gradients such that oxygen concentration reduced with increasing proximity to the cell. This technique provides a powerful tool for quantifying spatial oxygen gradients within three-dimensional cellular models.

An Application of X-ray Fluorescence as Process Analytical Technology (PAT) to Monitor Particle Coating Processes.

Science.gov (United States)

Nakano, Yoshio; Katakuse, Yoshimitsu; Azechi, Yasutaka

2018-03-30

An attempt to apply X-ray Fluorescence (XRF) analysis to evaluate small particle coating process as a Process Analytical Technologies (PAT) was made. The XRF analysis was used to monitor coating level in small particle coating process with at-line manner. The small particle coating process usually consists of multiple coating processes. This study was conducted by a simple coating particles prepared by first coating of a model compound (DL-methionine) and second coating by talc on spherical microcrystalline cellulose cores. The particles with two layered coating are enough to demonstrate the small particle coating process. From the result by the small particle coating process, it was found that the XRF signal played different roles, resulting that XRF signals by first coating (layering) and second coating (mask coating) could demonstrate the extent with different mechanisms for the coating process. Furthermore, the particle coating of the different particle size has also been investigated to evaluate size effect of these coating processes. From these results, it was concluded that the XRF could be used as a PAT in monitoring particle coating processes and become powerful tool in pharmaceutical manufacturing.

Centroids of effective interactions from measured single-particle energies: An application

International Nuclear Information System (INIS)

Cole, B.J.

1990-01-01

Centroids of the effective nucleon-nucleon interaction for the mass region A=28--64 are extracted directly from experimental single-particle spectra, by comparing single-particle energies relative to different cores. Uncertainties in the centroids are estimated at approximately 100 keV, except in cases of exceptional fragmentation of the single-particle strength. The use of a large number of inert cores allows the dependence of the interaction on mass or model space to be investigated. The method permits accurate empirical modifications to be made to realistic interactions calculated from bare nucleon-nucleon potentials, which are known to possess defective centroids in many cases. In addition, the centroids can be used as input to the more sophisticated fitting procedures that are employed to produce matrix elements of the effective interaction

Denaturing of single electrospun fibrinogen fibers studied by deep ultraviolet fluorescence microscopy.

Science.gov (United States)

Kim, Jeongyong; Song, Hugeun; Park, Inho; Carlisle, Christine R; Bonin, Keith; Guthold, Martin

2011-03-01

Deep ultraviolet (DUV) microscopy is a fluorescence microscopy technique to image unlabeled proteins via the native fluorescence of some of their amino acids. We constructed a DUV fluorescence microscope, capable of 280 nm wavelength excitation by modifying an inverted optical microscope. Moreover, we integrated a nanomanipulator-controlled micropipette into this instrument for precise delivery of picoliter amounts of fluid to selected regions of the sample. In proof-of-principle experiments, we used this instrument to study, in situ, the effect of a denaturing agent on the autofluorescence intensity of single, unlabeled, electrospun fibrinogen nanofibers. Autofluorescence emission from the nanofibers was excited at 280 nm and detected at ∼350 nm. A denaturant solution was discretely applied to small, select sections of the nanofibers and a clear local reduction in autofluorescence intensity was observed. This reduction is attributed to the dissolution of the fibers and the unfolding of proteins in the fibers. Copyright © 2010 Wiley-Liss, Inc.

Design of Fluorescent Compounds for Scintillation Detection

Energy Technology Data Exchange (ETDEWEB)

Pla-Dalmau, Anna [Northern Illinois U.

1990-01-01

Plastic scintillation detectors for high energy physics applications require the development of new fluorescent compounds to meet the demands set by the future generation of particle accelerators such as the Superconducting Supercollider (SSe). Plastic scintillators are commonly based on a polymer matrix doped with two fluorescent compounds: the primary dopant and the wavelength shifter. Their main characteristics are fast response time and high quantum efficiency. The exposure to larger radiation doses and demands for larger light output questions their survivability in the future experiments. A new type of plastic scintillator - intrinsic scintillator - has been suggested. It uses a single dopant as primary and wavelength shifter, and should be less susceptible to radiation damage....

Synchrotron x-ray fluorescence analyses of stratospheric cosmic dust: New results for chondritic and nickel-depleted particles

International Nuclear Information System (INIS)

Flynn, G.J.; Sutton, S.R.

1989-06-01

Trace element abundance determinations were performed using synchrotron x-ray fluorescence on nine particles collected from the stratosphere and classified as ''cosmic''. Improvements to the Synchrotron Light Source allowed the detection of all elements between Cr and Mo, with the exceptions of Co and As, in our largest particle. The minor and trace element abundance patterns of three Ni-depleted particles were remarkably similar to those of extraterrestrial igneous rocks. Fe/Ni and Fe/Mn ratios suggest that one of these may be of lunar origin. All nine particles exhibited an enrichment in Br, ranging form 1.3 to 38 times the Cl concentration. Br concentrations were uncorrelated with particle size, as would be expected for a surface correlated component acquires from the stratosphere. 27 refs., 4 figs., 2 tabs

Molecular and structural characterization of fluorescent human parvovirus B19 virus-like particles

International Nuclear Information System (INIS)

Gilbert, Leona; Toivola, Jouni; White, Daniel; Ihalainen, Teemu; Smith, Wesley; Lindholm, Laura; Vuento, Matti; Oker-Blom, Christian

2005-01-01

Although sharing a T = 1 icosahedral symmetry with other members of the Parvoviridae family, it has been suggested that the fivefold channel of the human parvovirus B19 VP2 capsids is closed at its outside end. To investigate the possibility of placing a relatively large protein moiety at this site of B19, fluorescent virus-like particles (fVLPs) of B19 were developed. The enhanced green fluorescent protein (EGFP) was inserted at the N-terminus of the structural protein VP2 and assembly of fVLPs from this fusion protein was obtained. Electron microscopy revealed that these fluorescent protein complexes were very similar in size when compared to wild-type B19 virus. Further, fluorescence correlation spectroscopy showed that an average of nine EGFP domains were associated with these virus-like structures. Atomic force microscopy and immunoprecipitation studies showed that EGFP was displayed on the surface of these fVLPs. Confocal imaging indicated that these chimeric complexes were targeted to late endosomes when expressed in insect cells. The fVLPs were able to efficiently enter cancer cells and traffic to the nucleus via the microtubulus network. Finally, immunoglobulins present in human parvovirus B19 acute and past-immunity serum samples were able to detect antigenic epitopes present in these fVLPs. In summary, we have developed fluorescent virus-like nanoparticles displaying a large heterologous entity that should be of help to elucidate the mechanisms of infection and pathogenesis of human parvovirus B19. In addition, these B19 nanoparticles serve as a model in the development of targetable vehicles designed for delivery of biomolecules

Improved identification of primary biological aerosol particles using single-particle mass spectrometry

Directory of Open Access Journals (Sweden)

M. A. Zawadowicz

2017-06-01

Full Text Available Measurements of primary biological aerosol particles (PBAP, especially at altitudes relevant to cloud formation, are scarce. Single-particle mass spectrometry (SPMS has been used to probe aerosol chemical composition from ground and aircraft for over 20 years. Here we develop a method for identifying bioaerosols (PBAP and particles containing fragments of PBAP as part of an internal mixture using SPMS. We show that identification of bioaerosol using SPMS is complicated because phosphorus-bearing mineral dust and phosphorus-rich combustion by-products such as fly ash produce mass spectra with peaks similar to those typically used as markers for bioaerosol. We have developed a methodology to differentiate and identify bioaerosol using machine learning statistical techniques applied to mass spectra of known particle types. This improved method provides far fewer false positives compared to approaches reported in the literature. The new method was then applied to two sets of ambient data collected at Storm Peak Laboratory and a forested site in Central Valley, California to show that 0.04–2 % of particles in the 200–3000 nm aerodynamic diameter range were identified as bioaerosol. In addition, 36–56 % of particles identified as biological also contained spectral features consistent with mineral dust, suggesting internal dust–biological mixtures.

Single-Molecule Plasmon Sensing: Current Status and Future Prospects.

Science.gov (United States)

Taylor, Adam B; Zijlstra, Peter

2017-08-25

Single-molecule detection has long relied on fluorescent labeling with high quantum-yield fluorophores. Plasmon-enhanced detection circumvents the need for labeling by allowing direct optical detection of weakly emitting and completely nonfluorescent species. This review focuses on recent advances in single molecule detection using plasmonic metal nanostructures as a sensing platform, particularly using a single particle-single molecule approach. In the past decade two mechanisms for plasmon-enhanced single-molecule detection have been demonstrated: (1) by plasmonically enhancing the emission of weakly fluorescent biomolecules, or (2) by monitoring shifts of the plasmon resonance induced by single-molecule interactions. We begin with a motivation regarding the importance of single molecule detection, and advantages plasmonic detection offers. We describe both detection mechanisms and discuss challenges and potential solutions. We finalize by highlighting the exciting possibilities in analytical chemistry and medical diagnostics.

Morphology of single inhalable particle inside public transit biodiesel fueled bus.

Science.gov (United States)

Shandilya, Kaushik K; Kumar, Ashok

2010-01-01

In an urban-transit bus, fueled by biodiesel in Toledo, Ohio, single inhalable particle samples in October 2008 were collected and detected by scanning electron microscopy and energy dispersive X-ray spectrometry (SEM/EDS). Particle size analysis found bimodal distribution at 0.2 and 0.5 microm. The particle morphology was characterized by 14 different shape clusters: square, pentagon, hexagon, heptagon, octagon, nonagon, decagon, agglomerate, sphere, triangle, oblong, strip, line or stick, and unknown, by quantitative order. The square particles were common in the samples. Round and triangle particles are more, and pentagon, hexagon, heptagon, octagon, nonagon, decagon, strip, line or sticks are less. Agglomerate particles were found in abundance. The surface of most particles was coarse with a fractal edge that can provide a suitable chemical reaction bed in the polluted atmospheric environment. The three sorts of surface patterns of squares were smooth, semi-smooth, and coarse. The three sorts of square surface patterns represented the morphological characteristics of single inhalable particles in the air inside the bus in Toledo. The size and shape distribution results were compared to those obtained for a bus using ultra low sulfur diesel.

Two-particle versus three-particle interactions in single ionization of helium by ion impact

International Nuclear Information System (INIS)

Schulz, M; Moshammer, R; Fischer, D; Ullrich, J

2004-01-01

We have performed kinematically complete experiments on single ionization of He by 100 MeV amu -1 C 6+ and 3.6 MeV amu -1 Au 24,53+ impact. By analysing doubly differential cross sections (DDCS) as a function of the momenta of all two-particle sub-systems we studied the importance of two-particle interactions. Furthermore, presenting the squared momenta of all three collision fragments simultaneously in a Dalitz plot, we evaluated the role of three-particle interactions. Finally, both for the DDCS and the Dalitz plots the corresponding correlation function was analysed. While the absolute cross sections confirm that ionization predominantly leads to a momentum exchange between the electron and the recoil-ion, the correlation function reveals strong correlations between the particles of any two-particle sub-system. Three-particle correlations, which are not accounted for by perturbative calculations, are quite significant as well, at least for certain kinematic conditions

Single-particle electron microscopy in the study of membrane protein structure.

Science.gov (United States)

De Zorzi, Rita; Mi, Wei; Liao, Maofu; Walz, Thomas

2016-02-01

Single-particle electron microscopy (EM) provides the great advantage that protein structure can be studied without the need to grow crystals. However, due to technical limitations, this approach played only a minor role in the study of membrane protein structure. This situation has recently changed dramatically with the introduction of direct electron detection device cameras, which allow images of unprecedented quality to be recorded, also making software algorithms, such as three-dimensional classification and structure refinement, much more powerful. The enhanced potential of single-particle EM was impressively demonstrated by delivering the first long-sought atomic model of a member of the biomedically important transient receptor potential channel family. Structures of several more membrane proteins followed in short order. This review recounts the history of single-particle EM in the study of membrane proteins, describes the technical advances that now allow this approach to generate atomic models of membrane proteins and provides a brief overview of some of the membrane protein structures that have been studied by single-particle EM to date. © The Author 2015. Published by Oxford University Press on behalf of The Japanese Society of Microscopy. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

On-Chip Magnetic Platform for Single-Particle Manipulation with Integrated Electrical Feedback.

Science.gov (United States)

Monticelli, Marco; Torti, Andrea; Cantoni, Matteo; Petti, Daniela; Albisetti, Edoardo; Manzin, Alessandra; Guerriero, Erica; Sordan, Roman; Gervasoni, Giacomo; Carminati, Marco; Ferrari, Giorgio; Sampietro, Marco; Bertacco, Riccardo

2016-02-17

Methods for the manipulation of single magnetic particles have become very interesting, in particular for in vitro biological studies. Most of these studies require an external microscope to provide the operator with feedback for controlling the particle motion, thus preventing the use of magnetic particles in high-throughput experiments. In this paper, a simple and compact system with integrated electrical feedback is presented, implementing in the very same device both the manipulation and detection of the transit of single particles. The proposed platform is based on zig-zag shaped magnetic nanostructures, where transverse magnetic domain walls are pinned at the corners and attract magnetic particles in suspension. By applying suitable external magnetic fields, the domain walls move to the nearest corner, thus causing the step by step displacement of the particles along the nanostructure. The very same structure is also employed for detecting the bead transit. Indeed, the presence of the magnetic particle in suspension over the domain wall affects the depinning field required for its displacement. This characteristic field can be monitored through anisotropic magnetoresistance measurements, thus implementing an integrated electrical feedback of the bead transit. In particular, the individual manipulation and detection of single 1-μm sized beads is demonstrated. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Picosecond wide-field time-correlated single photon counting fluorescence microscopy with a delay line anode detector

Energy Technology Data Exchange (ETDEWEB)

Hirvonen, Liisa M.; Le Marois, Alix; Suhling, Klaus, E-mail: klaus.suhling@kcl.ac.uk [Department of Physics, King' s College London, Strand, London WC2R 2LS (United Kingdom); Becker, Wolfgang; Smietana, Stefan [Becker & Hickl GmbH, Nahmitzer Damm 30, 12277 Berlin (Germany); Milnes, James; Conneely, Thomas [Photek Ltd., 26 Castleham Rd, Saint Leonards-on-Sea TN38 9NS (United Kingdom); Jagutzki, Ottmar [Institut für Kernphysik, Max-von-Laue-Str. 1, 60438 Frankfurt (Germany)

2016-08-15

We perform wide-field time-correlated single photon counting-based fluorescence lifetime imaging (FLIM) with a crossed delay line anode image intensifier, where the pulse propagation time yields the photon position. This microchannel plate-based detector was read out with conventional fast timing electronics and mounted on a fluorescence microscope with total internal reflection (TIR) illumination. The picosecond time resolution of this detection system combines low illumination intensity of microwatts with wide-field data collection. This is ideal for fluorescence lifetime imaging of cell membranes using TIR. We show that fluorescence lifetime images of living HeLa cells stained with membrane dye di-4-ANEPPDHQ exhibit a reduced lifetime near the coverslip in TIR compared to epifluorescence FLIM.

Localization and force analysis at the single virus particle level using atomic force microscopy

International Nuclear Information System (INIS)

Liu, Chih-Hao; Horng, Jim-Tong; Chang, Jeng-Shian; Hsieh, Chung-Fan; Tseng, You-Chen; Lin, Shiming

2012-01-01

Highlights: ► Localization of single virus particle. ► Force measurements. ► Force mapping. -- Abstract: Atomic force microscopy (AFM) is a vital instrument in nanobiotechnology. In this study, we developed a method that enables AFM to simultaneously measure specific unbinding force and map the viral glycoprotein at the single virus particle level. The average diameter of virus particles from AFM images and the specificity between the viral surface antigen and antibody probe were integrated to design a three-stage method that sets the measuring area to a single virus particle before obtaining the force measurements, where the influenza virus was used as the object of measurements. Based on the purposed method and performed analysis, several findings can be derived from the results. The mean unbinding force of a single virus particle can be quantified, and no significant difference exists in this value among virus particles. Furthermore, the repeatability of the proposed method is demonstrated. The force mapping images reveal that the distributions of surface viral antigens recognized by antibody probe were dispersed on the whole surface of individual virus particles under the proposed method and experimental criteria; meanwhile, the binding probabilities are similar among particles. This approach can be easily applied to most AFM systems without specific components or configurations. These results help understand the force-based analysis at the single virus particle level, and therefore, can reinforce the capability of AFM to investigate a specific type of viral surface protein and its distributions.

Quantifying the Assembly of Multicomponent Molecular Machines by Single-Molecule Total Internal Reflection Fluorescence Microscopy.

Science.gov (United States)

Boehm, E M; Subramanyam, S; Ghoneim, M; Washington, M Todd; Spies, M

2016-01-01

Large, dynamic macromolecular complexes play essential roles in many cellular processes. Knowing how the components of these complexes associate with one another and undergo structural rearrangements is critical to understanding how they function. Single-molecule total internal reflection fluorescence (TIRF) microscopy is a powerful approach for addressing these fundamental issues. In this article, we first discuss single-molecule TIRF microscopes and strategies to immobilize and fluorescently label macromolecules. We then review the use of single-molecule TIRF microscopy to study the formation of binary macromolecular complexes using one-color imaging and inhibitors. We conclude with a discussion of the use of TIRF microscopy to examine the formation of higher-order (i.e., ternary) complexes using multicolor setups. The focus throughout this article is on experimental design, controls, data acquisition, and data analysis. We hope that single-molecule TIRF microscopy, which has largely been the province of specialists, will soon become as common in the tool box of biophysicists and biochemists as structural approaches have become today. © 2016 Elsevier Inc. All rights reserved.

Single particle behaviour in circulating fluidized bed combustors

DEFF Research Database (Denmark)

Erik Weinell, Claus

1994-01-01

An investigation of single particle behaviour in a circulating fluidized bed combustor is described, relating to sulphur capture reactions by limestone under alternate oxidizing and reducing conditions present in a circulating fluidized bed combustor, and to the devolatilization and burn out...

A deep convolutional neural network approach to single-particle recognition in cryo-electron microscopy.

Science.gov (United States)

Zhu, Yanan; Ouyang, Qi; Mao, Youdong

2017-07-21

Single-particle cryo-electron microscopy (cryo-EM) has become a mainstream tool for the structural determination of biological macromolecular complexes. However, high-resolution cryo-EM reconstruction often requires hundreds of thousands of single-particle images. Particle extraction from experimental micrographs thus can be laborious and presents a major practical bottleneck in cryo-EM structural determination. Existing computational methods for particle picking often use low-resolution templates for particle matching, making them susceptible to reference-dependent bias. It is critical to develop a highly efficient template-free method for the automatic recognition of particle images from cryo-EM micrographs. We developed a deep learning-based algorithmic framework, DeepEM, for single-particle recognition from noisy cryo-EM micrographs, enabling automated particle picking, selection and verification in an integrated fashion. The kernel of DeepEM is built upon a convolutional neural network (CNN) composed of eight layers, which can be recursively trained to be highly "knowledgeable". Our approach exhibits an improved performance and accuracy when tested on the standard KLH dataset. Application of DeepEM to several challenging experimental cryo-EM datasets demonstrated its ability to avoid the selection of un-wanted particles and non-particles even when true particles contain fewer features. The DeepEM methodology, derived from a deep CNN, allows automated particle extraction from raw cryo-EM micrographs in the absence of a template. It demonstrates an improved performance, objectivity and accuracy. Application of this novel method is expected to free the labor involved in single-particle verification, significantly improving the efficiency of cryo-EM data processing.

Projection operator treatment of single particle resonances

International Nuclear Information System (INIS)

Lev, A.; Beres, W.P.

1976-01-01

A projection operator method is used to obtain the energy and width of a single particle resonance. The resonance energy is found without scanning. An example of the first g/sub 9/2/ neutron resonance in 40 Ca is given and compared with the traditional phase shift method. The results of both approaches are quite similar. 4 figures

Comment on ’Single Pentacene Molecules Detected by Fluorescence Excitation in a P-Terphenyl Crystal’

Science.gov (United States)

1990-12-10

8217 NO 11 TITLE (include Security Classification) Comment on "Single Pentacene Molecules Detected by Fluorescence Excitation in a p-Terphenyl Crystal" 12...8217 {Continue on reverse it necessary and identify by block numboer) Using h--,Ihly efficient Fluorescence excitation spectroscov of individual pentacene ...molecular impurities in p-terphenvl crystals, we have observed that some pentacene defects exhibit spcntaneous spectral jumps in their resonance frequency at

Bright and photostable nitrogen-vacancy fluorescence from unprocessed detonation nanodiamond.

Science.gov (United States)

Reineck, P; Capelli, M; Lau, D W M; Jeske, J; Field, M R; Ohshima, T; Greentree, A D; Gibson, B C

2017-01-05

Bright and photostable fluorescence from nitrogen-vacancy (NV) centers is demonstrated in unprocessed detonation nanodiamond particle aggregates. The optical properties of these particles is analyzed using confocal fluorescence microscopy and spectroscopy, time resolved fluorescence decay measurements, and optically detected magnetic resonance experiments. Two particle populations with distinct optical properties are identified and compared to high-pressure high-temperature (HPHT) fluorescent nanodiamonds. We find that the brightness of one detonation nanodiamond particle population is on the same order as that of highly processed fluorescent 100 nm HPHT nanodiamonds. Our results may open the path to a simple and up-scalable route for the production of fluorescent NV nanodiamonds for use in bioimaging applications.

Individual particle analysis of coarse air suspended particulate material by synchrotron radiation X-ray micro fluorescence

International Nuclear Information System (INIS)

Moreira, Silvana; Melo Junior, Ariston; Vives, Ana Elisa S. de; Nascimento Filho, Virgilio F.

2005-01-01

The purpose of this work is evaluate the size of individual particles present in the air suspended particulate material collected in Campinas, Sao Paulo State, and analyze quantitatively the particles using the synchrotron radiation X-ray micro fluorescence (μ-SRXRF) associated with the fundamental parameter method to correct attenuation/absorption effects by the matrix. The particles analyzed have size between 50-10 μm and to perform the spatial distribution a white beam of synchrotron radiation condensed by a conical capillary (13 μm diameter) was used. For the quantitative analysis punctual measures in thin films standards in Mylar subtract were performed. The elements detected were Si, S, Cl, K, Ca, Ti, V, Cr, Mn, Fe, Ni, Cu, Zn, Ba and Pb. (author)

Individual particle analysis of coarse air suspended particulate material by synchrotron radiation X-ray micro fluorescence

Energy Technology Data Exchange (ETDEWEB)

Moreira, Silvana; Melo Junior, Ariston [Universidade Estadual de Campinas, SP (Brazil). Faculdade de Engenharia Civil, Arquitetura e Urbanismo. Dept. de Recursos Hidricos]. E-mail: silvana@fec.unicamp.br; Perez, Carlos Alberto [Laboratorio Nacional de Luz Sincrotron (LNLS), Campinas, SP (Brazil)]. E-mail: perez@lnls.br; Vives, Ana Elisa S. de [Universidade Metodista de Piracicaba (UNIMEP), Santa Barbara D' Oeste, SP (Brazil). Faculdade de Engenharia, Arquitetura e Urbanismo]. E-mail: aesvives@unimep.br; Nascimento Filho, Virgilio F. [Centro de Energia Nuclear na Agricultura (CENA), Piracicaba, SP (Brazil). Lab. de Instrumentacao Nuclear]. E-mail: virgilio@cena.usp.br

2005-07-01

The purpose of this work is evaluate the size of individual particles present in the air suspended particulate material collected in Campinas, Sao Paulo State, and analyze quantitatively the particles using the synchrotron radiation X-ray micro fluorescence ({mu}-SRXRF) associated with the fundamental parameter method to correct attenuation/absorption effects by the matrix. The particles analyzed have size between 50-10 {mu}m and to perform the spatial distribution a white beam of synchrotron radiation condensed by a conical capillary (13 {mu}m diameter) was used. For the quantitative analysis punctual measures in thin films standards in Mylar subtract were performed. The elements detected were Si, S, Cl, K, Ca, Ti, V, Cr, Mn, Fe, Ni, Cu, Zn, Ba and Pb. (author)

Determination of particle-release conditions in microfiltration: A simple single-particle model tested on a model membrane

NARCIS (Netherlands)

Kuiper, S.; van Rijn, C.J.M.; Nijdam, W.; Krijnen, Gijsbertus J.M.; Elwenspoek, Michael Curt

2000-01-01

A simple single-particle model was developed for cross-flow microfiltration with microsieves. The model describes the cross-flow conditions required to release a trapped spherical particle from a circular pore. All equations are derived in a fully analytical way without any fitting parameters. For

Acoustic Manipulation of Particles and Fluids in Microfluidic Systems

OpenAIRE

Johansson, Linda

2009-01-01

The downscaling and integration of biomedical analyses onto a single chip offers several advantages in speed, cost, parallelism and de-centralization. Acoustic radiation forces are attractive to use in these applications since they are strong, long-range and gentle. Lab-on-a-chip operations such as cell trapping, particle fluorescence activated cell sorting, fluid mixing and particle sorting performed by acoustic radiation forces are exploited in this thesis. Two different platforms are desig...

Localization and force analysis at the single virus particle level using atomic force microscopy

Energy Technology Data Exchange (ETDEWEB)

Liu, Chih-Hao [Institute of Applied Mechanics, Nation Taiwan University, Roosevelt Road, Taipei 10617, Taiwan (China); Horng, Jim-Tong [Department of Biochemistry, Chang Gung University, 259 Wen-Hwa First Road, Kweishan, Taoyuan 333, Taiwan (China); Chang, Jeng-Shian [Institute of Applied Mechanics, Nation Taiwan University, Roosevelt Road, Taipei 10617, Taiwan (China); Hsieh, Chung-Fan [Graduate Institute of Biomedical Sciences, Chang Gung University, Kweishan, Taoyuan 333, Taiwan (China); Tseng, You-Chen [Institute of Applied Mechanics, Nation Taiwan University, Roosevelt Road, Taipei 10617, Taiwan (China); Lin, Shiming, E-mail: til@ntu.edu.tw [Institute of Applied Mechanics, Nation Taiwan University, Roosevelt Road, Taipei 10617, Taiwan (China); Center for Optoelectronic Biomedicine, College of Medicine, Nation Taiwan University, 1-1 Jen-Ai Road, Taipei 10051, Taiwan (China)

2012-01-06

Highlights: Black-Right-Pointing-Pointer Localization of single virus particle. Black-Right-Pointing-Pointer Force measurements. Black-Right-Pointing-Pointer Force mapping. -- Abstract: Atomic force microscopy (AFM) is a vital instrument in nanobiotechnology. In this study, we developed a method that enables AFM to simultaneously measure specific unbinding force and map the viral glycoprotein at the single virus particle level. The average diameter of virus particles from AFM images and the specificity between the viral surface antigen and antibody probe were integrated to design a three-stage method that sets the measuring area to a single virus particle before obtaining the force measurements, where the influenza virus was used as the object of measurements. Based on the purposed method and performed analysis, several findings can be derived from the results. The mean unbinding force of a single virus particle can be quantified, and no significant difference exists in this value among virus particles. Furthermore, the repeatability of the proposed method is demonstrated. The force mapping images reveal that the distributions of surface viral antigens recognized by antibody probe were dispersed on the whole surface of individual virus particles under the proposed method and experimental criteria; meanwhile, the binding probabilities are similar among particles. This approach can be easily applied to most AFM systems without specific components or configurations. These results help understand the force-based analysis at the single virus particle level, and therefore, can reinforce the capability of AFM to investigate a specific type of viral surface protein and its distributions.

One-step synthesis of dye-incorporated porous silica particles

Energy Technology Data Exchange (ETDEWEB)

Liu Qing; DeShong, Philip; Zachariah, Michael R., E-mail: mrz@umd.edu [University of Maryland, Department of Chemistry and Biochemistry (United States)

2012-07-15

Fluorescent nanoparticles have a variety of biomedical applications as diagnostics and traceable drug delivery agents. Highly fluorescent porous silica nanoparticles were synthesized in a water/oil phase by a microemulsion method. What is unique about the resulting porous silica nanoparticles is the combination of a single-step, efficient synthesis and the high stability of its fluorescence emission in the resulting materials. The key of the success of this approach is the choice of a lipid dye that functions as a surrogate surfactant in the preparation. The surfactant dye was incorporated at the interface of the inorganic silica matrix and organic environment (pore template), and thus insures the stability of the dye-silica hybrid structure. The resulting fluorescent silica materials have a number of properties that make them attractive for biomedical applications: the availability of various color of the resulting nanoparticle from among a broad spectrum of commercially dyes, the controllablity of pore size (diameters of {approx}5 nm) and particle size (diameters of {approx}40 nm) by adjusting template monomer concentration and the water/oil ratio, and the stability and durability of particle fluorescence because of the deep insertion of surfactant's tail into the silica matrix.

Single-particle characterization of the high-Arctic summertime aerosol

Directory of Open Access Journals (Sweden)

B. Sierau

2014-07-01

Full Text Available Single-particle mass-spectrometric measurements were carried out in the high Arctic north of 80° during summer 2008. The campaign took place onboard the icebreaker Oden and was part of the Arctic Summer Cloud Ocean Study (ASCOS. The instrument deployed was an aerosol time-of-flight mass spectrometer (ATOFMS that provides information on the chemical composition of individual particles and their mixing state in real time. Aerosols were sampled in the marine boundary layer at stations in the open ocean, in the marginal ice zone, and in the pack ice region. The largest fraction of particles detected for subsequent analysis in the size range of the ATOFMS between approximately 200 and 3000 nm in diameter showed mass-spectrometric patterns, indicating an internal mixing state and a biomass burning and/or biofuel source. The majority of these particles were connected to an air mass layer of elevated particle concentration mixed into the surface mixed layer from the upper part of the marine boundary layer. The second largest fraction was represented by sea salt particles. The chemical analysis of the over-ice sea salt aerosol revealed tracer compounds that reflect chemical aging of the particles during their long-range advection from the marginal ice zone, or open waters south thereof prior to detection at the ship. From our findings we conclude that long-range transport of particles is one source of aerosols in the high Arctic. To assess the importance of long-range particle sources for aerosol–cloud interactions over the inner Arctic in comparison to local and regional biogenic primary aerosol sources, the chemical composition of the detected particles was analyzed for indicators of marine biological origin. Only a minor fraction showed chemical signatures of potentially ocean-derived primary particles of that kind. However, a chemical bias in the ATOFMS's detection capabilities observed during ASCOS might suggest the presence of a particle type of

Single-particle characterization of the high-Arctic summertime aerosol

Science.gov (United States)

Sierau, B.; Chang, R. Y.-W.; Leck, C.; Paatero, J.; Lohmann, U.

2014-07-01

Single-particle mass-spectrometric measurements were carried out in the high Arctic north of 80° during summer 2008. The campaign took place onboard the icebreaker Oden and was part of the Arctic Summer Cloud Ocean Study (ASCOS). The instrument deployed was an aerosol time-of-flight mass spectrometer (ATOFMS) that provides information on the chemical composition of individual particles and their mixing state in real time. Aerosols were sampled in the marine boundary layer at stations in the open ocean, in the marginal ice zone, and in the pack ice region. The largest fraction of particles detected for subsequent analysis in the size range of the ATOFMS between approximately 200 and 3000 nm in diameter showed mass-spectrometric patterns, indicating an internal mixing state and a biomass burning and/or biofuel source. The majority of these particles were connected to an air mass layer of elevated particle concentration mixed into the surface mixed layer from the upper part of the marine boundary layer. The second largest fraction was represented by sea salt particles. The chemical analysis of the over-ice sea salt aerosol revealed tracer compounds that reflect chemical aging of the particles during their long-range advection from the marginal ice zone, or open waters south thereof prior to detection at the ship. From our findings we conclude that long-range transport of particles is one source of aerosols in the high Arctic. To assess the importance of long-range particle sources for aerosol-cloud interactions over the inner Arctic in comparison to local and regional biogenic primary aerosol sources, the chemical composition of the detected particles was analyzed for indicators of marine biological origin. Only a minor fraction showed chemical signatures of potentially ocean-derived primary particles of that kind. However, a chemical bias in the ATOFMS's detection capabilities observed during ASCOS might suggest the presence of a particle type of unknown composition

Single-particle characterization of the High Arctic summertime aerosol

Science.gov (United States)

Sierau, B.; Chang, R. Y.-W.; Leck, C.; Paatero, J.; Lohmann, U.

2014-01-01

Single-particle mass spectrometric measurements were carried out in the High Arctic north of 80° during summer 2008. The campaign took place onboard the icebreaker Oden and was part of the Arctic Summer Cloud Ocean Study (ASCOS). The instrument deployed was an Aerosol Time-of-Flight Mass Spectrometer (ATOFMS) that provides information on the chemical composition of individual particles and their mixing state in real-time. Aerosols were sampled in the marine boundary layer at stations in the open ocean, in the marginal ice zone, and in the pack ice region. The largest fraction of particles detected for subsequent analysis in the size range of the ATOFMS between approximately 200 nm to 3000 nm in diameter showed mass spectrometric patterns indicating an internal mixing state and a biomass burning and/or biofuel source. The majority of these particles were connected to an air mass layer of elevated particle concentration mixed into the surface mixed layer from the upper part of the marine boundary layer. The second largest fraction was represented by sea salt particles. The chemical analysis of the over-ice sea salt aerosol revealed tracer compounds that reflect chemical aging of the particles during their long-range advection from the marginal ice zone, or open waters south thereof prior to detection at the ship. From our findings we conclude that long-range transport of particles is one source of aerosols in the High Arctic. To assess the importance of long-range particle sources for aerosol-cloud interactions over the inner Arctic in comparison to local and regional biogenic primary aerosol sources, the chemical composition of the detected particles was analyzed for indicators of marine biological origin. Only a~minor fraction showed chemical signatures of potentially ocean-derived primary particles of that kind. However, a chemical bias in the ATOFMS's detection capabilities observed during ASCOS might suggest a presence of a particle type of unknown composition

Laser-Induced Fluorescence Detection in High-Throughput Screening of Heterogeneous Catalysts and Single Cells Analysis

Energy Technology Data Exchange (ETDEWEB)

Su, Hui [Iowa State Univ., Ames, IA (United States)

2001-01-01

Laser-induced fluorescence detection is one of the most sensitive detection techniques and it has found enormous applications in various areas. The purpose of this research was to develop detection approaches based on laser-induced fluorescence detection in two different areas, heterogeneous catalysts screening and single cell study. First, the author introduced laser-induced imaging (LIFI) as a high-throughput screening technique for heterogeneous catalysts to explore the use of this high-throughput screening technique in discovery and study of various heterogeneous catalyst systems. This scheme is based on the fact that the creation or the destruction of chemical bonds alters the fluorescence properties of suitably designed molecules. By irradiating the region immediately above the catalytic surface with a laser, the fluorescence intensity of a selected product or reactant can be imaged by a charge-coupled device (CCD) camera to follow the catalytic activity as a function of time and space. By screening the catalytic activity of vanadium pentoxide catalysts in oxidation of naphthalene, they demonstrated LIFI has good detection performance and the spatial and temporal resolution needed for high-throughput screening of heterogeneous catalysts. The sample packing density can reach up to 250 x 250 subunits/cm² for 40-μm wells. This experimental set-up also can screen solid catalysts via near infrared thermography detection. In the second part of this dissertation, the author used laser-induced native fluorescence coupled with capillary electrophoresis (LINF-CE) and microscope imaging to study the single cell degranulation. On the basis of good temporal correlation with events observed through an optical microscope, they have identified individual peaks in the fluorescence electropherograms as serotonin released from the granular core on contact with the surrounding fluid.

Collective and single-particle states at high excitation energy

International Nuclear Information System (INIS)

Van den Berg, A.M.; Van der Molen, H.K.T.; Harakeh, M.N.; Akimune, H.; Daito, I.; Fujimura, H.; Fujiwara, M.; Ihara, F.; Inomata, T.

2000-01-01

Complete text of publication follows. Damping of high-lying single-particle states was investigated by the study of proton decay from high-lying states in 91 Nb, populated by the 90 Zr(α,t) reaction with E α = 180 MeV. In addition to decay to the ground state of 90 Zr, semi-direct decay was observed to the low-lying (2 + and 3 - ) phonon states, confirming the conclusion from other experiments that these phonon states play an important role in the damping process of the single-particle states. Furthermore, the population and decay of Isobaric Analogue States of 91 Zr, which are located at an excitation energy of about 10 - 12 MeV in 91 Nb, has been studied in the same reaction. (author)

Fractal and Morphological Characteristics of Single Marble Particle Crushing in Uniaxial Compression Tests

Directory of Open Access Journals (Sweden)

Yidong Wang

2015-01-01

Full Text Available Crushing of rock particles is a phenomenon commonly encountered in geotechnical engineering practice. It is however difficult to study the crushing of rock particles using classical theory because the physical structure of the particles is complex and irregular. This paper aims at evaluating fractal and morphological characteristics of single rock particle. A large number of particle crushing tests are conducted on single rock particle. The force-displacement curves and the particle size distributions (PSD of crushed particles are analysed based on particle crushing tests. Particle shape plays an important role in both the micro- and macroscale responses of a granular assembly. The PSD of an assortment of rocks are analysed by fractal methods, and the fractal dimension is obtained. A theoretical formula for particle crushing strength is derived, utilising the fractal model, and a simple method is proposed for predicting the probability of particle survival based on the Weibull statistics. Based on a few physical assumptions, simple equations are derived for determining particle crushing energy. The results of applying these equations are tested against the actual experimental data and prove to be very consistent. Fractal theory is therefore applicable for analysis of particle crushing.

Real-time analysis of insoluble particles in glacial ice using single-particle mass spectrometry

Science.gov (United States)

Osman, Matthew; Zawadowicz, Maria A.; Das, Sarah B.; Cziczo, Daniel J.

2017-11-01

Insoluble aerosol particles trapped in glacial ice provide insight into past climates, but analysis requires information on climatically relevant particle properties, such as size, abundance, and internal mixing. We present a new analytical method using a time-of-flight single-particle mass spectrometer (SPMS) to determine the composition and size of insoluble particles in glacial ice over an aerodynamic size range of ˜ 0.2-3.0 µm diameter. Using samples from two Greenland ice cores, we developed a procedure to nebulize insoluble particles suspended in melted ice, evaporate condensed liquid from those particles, and transport them to the SPMS for analysis. We further determined size-dependent extraction and instrument transmission efficiencies to investigate the feasibility of determining particle-class-specific mass concentrations. We find SPMS can be used to provide constraints on the aerodynamic size, composition, and relative abundance of most insoluble particulate classes in ice core samples. We describe the importance of post-aqueous processing to particles, a process which occurs due to nebulization of aerosols from an aqueous suspension of originally soluble and insoluble aerosol components. This study represents an initial attempt to use SPMS as an emerging technique for the study of insoluble particulates in ice cores.

Single-particle spectral density of the Hubbard model

NARCIS (Netherlands)

Mehlig, B.; Eskes, H.; Hayn, R.; Meinders, M.B.J.

1995-01-01

We calculate the single-particle spectral function for the Hubbard model within the framework of a projection technique equivalent to the two-pole approximation. We show that the two-pole approximation can be well understood as an average characterization of the upper and the lower Hubbard bands,

SINGLE-PARTICLE SPECTRAL DENSITY OF THE HUBBARD-MODEL

NARCIS (Netherlands)

MEHLIG, B; ESKES, H; HAYN, R; MEINDERS, MBJ

1995-01-01

We calculate the single-particle spectral function for the Hubbard model within the framework of a projection technique equivalent to the two-pole approximation. We show that the two-pole approximation can be well understood as an average characterization of the upper and the lower Hubbard bands,

Single particle dynamics of many-body systems described by Vlasov-Fokker-Planck equations

International Nuclear Information System (INIS)

Frank, T.D.

2003-01-01

Using Langevin equations we describe the random walk of single particles that belong to particle systems satisfying Vlasov-Fokker-Planck equations. In doing so, we show that Haissinski distributions of bunched particles in electron storage rings can be derived from a particle dynamics model

Damping of unbound single-particle modes

International Nuclear Information System (INIS)

Fortier, S.; Beaumel, D.; Gales, S.; Guillot, J.; Langevin-Joliot, H.; Laurent, H.; Maison, J.M.; Bordewijk, J.; Brandenburg, S.; Krasznahorkay, A.; Crawley, G.M.; Massolo, C.P.; Renteria, M.; Khendriche, A.

1995-01-01

The (α, 3 He-n) reaction has been investigated at 120 MeV incident energy on 64 Ni, 90 Zr, and 120 Sn target nuclei. Neutrons in coincidence with 3 He particles emitted at 0 degree were detected using the multidetector array EDEN, in order to get information about the decay of single-particle states embedded in the (α, 3 He) continuum. Neutron angular correlations, multiplicity values, and branching ratios to low-lying states of the final nuclei have been compared with the predictions of the statistical decay model. Evidence for a significant nonstatistical decay branch has been observed in the three nuclei below about 15 MeV excitation energy. Direct branching ratios in 91 Zr deduced from this analysis are compared with the predictions of two nuclear structure models. At higher excitation energy, the decay characteristics of the (α, 3 He) continuum are shown to be mainly statistical

Comparison of molecular imprinted particles prepared using precipitation polymerization in water and chloroform for fluorescent detection of nitroaromatics

Energy Technology Data Exchange (ETDEWEB)

Stringer, R. Cody, E-mail: rcsm84@mail.mizzou.edu [Department of Biological Engineering, University of Missouri, Columbia, MO (United States); Gangopadhyay, Shubhra, E-mail: gangopadhyays@missouri.edu [Department of Electrical and Computer Engineering, University of Missouri, Columbia, MO (United States); Grant, Sheila A., E-mail: grantsa@missouri.edu [Department of Biological Engineering, University of Missouri, Columbia, MO (United States)

2011-10-10

Highlights: {yields} Imprinted polymers prepared using precipitation polymerization. {yields} Comparison of chloroform and water as polymerization solvent. {yields} Imprinted polymer doped with quantum dots for fluorescent sensor. {yields} Fluorescent imprinted polymer used to detect nitroaromatic explosives. {yields} Chloroform is ideal solvent for molecular imprinting of nitroaromatics. - Abstract: A comparative study was conducted to study the effects that two different polymerization solvents would have on the properties of imprinted polymer microparticles prepared using precipitation polymerization. Microparticles prepared in chloroform, which previous results indicated was the optimal solvent for molecular imprinting of nitroaromatic explosive compounds, were compared to water, which was hypothesized to decrease water swelling of the polymer and allow enhanced rebinding of aqueous template. The microparticles were characterized and were integrated into a fluorescence sensing mechanism for detection of nitroaromatic explosive compounds. The performance of the sensing mechanisms was compared to illustrate which polymerization solvent produced optimal imprinted polymer microparticles for detection of nitroaromatic molecules. Results indicated that the structures of microparticles synthesized in chloroform versus water varied greatly. Sensor performance studies showed that the microparticles prepared in chloroform had greater imprinting efficiency and higher template rebinding than those prepared in water. For detection of 2,4,6-trinitrotoluene, the chloroform-based fluorescent microparticles achieved a lower limit of detection of 0.1 {mu}M, as compared to 100 {mu}M for the water-based fluorescent microparticles. Detection limits for 2,4-dinitrotoluene, as well as time response studies, also demonstrated that the chloroform-based particles are more effective for detection of nitroaromatic compounds than water-based particles. These results illustrate that the

Comparison of molecular imprinted particles prepared using precipitation polymerization in water and chloroform for fluorescent detection of nitroaromatics

International Nuclear Information System (INIS)

Stringer, R. Cody; Gangopadhyay, Shubhra; Grant, Sheila A.

2011-01-01

Highlights: → Imprinted polymers prepared using precipitation polymerization. → Comparison of chloroform and water as polymerization solvent. → Imprinted polymer doped with quantum dots for fluorescent sensor. → Fluorescent imprinted polymer used to detect nitroaromatic explosives. → Chloroform is ideal solvent for molecular imprinting of nitroaromatics. - Abstract: A comparative study was conducted to study the effects that two different polymerization solvents would have on the properties of imprinted polymer microparticles prepared using precipitation polymerization. Microparticles prepared in chloroform, which previous results indicated was the optimal solvent for molecular imprinting of nitroaromatic explosive compounds, were compared to water, which was hypothesized to decrease water swelling of the polymer and allow enhanced rebinding of aqueous template. The microparticles were characterized and were integrated into a fluorescence sensing mechanism for detection of nitroaromatic explosive compounds. The performance of the sensing mechanisms was compared to illustrate which polymerization solvent produced optimal imprinted polymer microparticles for detection of nitroaromatic molecules. Results indicated that the structures of microparticles synthesized in chloroform versus water varied greatly. Sensor performance studies showed that the microparticles prepared in chloroform had greater imprinting efficiency and higher template rebinding than those prepared in water. For detection of 2,4,6-trinitrotoluene, the chloroform-based fluorescent microparticles achieved a lower limit of detection of 0.1 μM, as compared to 100 μM for the water-based fluorescent microparticles. Detection limits for 2,4-dinitrotoluene, as well as time response studies, also demonstrated that the chloroform-based particles are more effective for detection of nitroaromatic compounds than water-based particles. These results illustrate that the enhanced chemical properties of

Silica encapsulation of fluorescent nanodiamonds for colloidal stability and facile surface functionalization.

Science.gov (United States)

Bumb, Ambika; Sarkar, Susanta K; Billington, Neil; Brechbiel, Martin W; Neuman, Keir C

2013-05-29

Fluorescent nanodiamonds (FNDs) emit in the near-IR and do not photobleach or photoblink. These properties make FNDs better suited for numerous imaging applications compared with commonly used fluorescence agents such as organic dyes and quantum dots. However, nanodiamonds do not form stable suspensions in aqueous buffer, are prone to aggregation, and are difficult to functionalize. Here we present a method for encapsulating nanodiamonds with silica using an innovative liposome-based encapsulation process that renders the particle surface biocompatible, stable, and readily functionalized through routine linking chemistries. Furthermore, the method selects for a desired particle size and produces a monodisperse agent. We attached biotin to the silica-coated FNDs and tracked the three-dimensional motion of a biotinylated FND tethered by a single DNA molecule with high spatial and temporal resolution.

Study of the fluorescence blinking behavior of single F2 color centers in LiF crystal

International Nuclear Information System (INIS)

Boichenko, S V; Koenig, K; Zilov, S A; Dresvianskiy, V P; Rakevich, A L; Kuznetsov, A V; Bartul, A V; Martynovich, E F; Voitovich, A P

2014-01-01

Using confocal fluorescence microscopy technique, we observed experimentally the luminescence of single F 2 color centers in LiF crystal. It is disclosed that the fluorescence shows blinking behavior. It is shown that this phenomenon is caused by the F 2 center reorientation occurring during the experiment. The ratio of luminescence intensities of differently oriented centers is assessed theoretically for two different experiment configurations. The calculated ratios are in fine agreement with experimental result

Reconstructing an icosahedral virus from single-particle diffraction experiments

Science.gov (United States)

Saldin, D. K.; Poon, H.-C.; Schwander, P.; Uddin, M.; Schmidt, M.

2011-08-01

The first experimental data from single-particle scattering experiments from free electron lasers (FELs) are now becoming available. The first such experiments are being performed on relatively large objects such as viruses, which produce relatively low-resolution, low-noise diffraction patterns in so-called ``diffract-and-destroy'' experiments. We describe a very simple test on the angular correlations of measured diffraction data to determine if the scattering is from an icosahedral particle. If this is confirmed, the efficient algorithm proposed can then combine diffraction data from multiple shots of particles in random unknown orientations to generate a full 3D image of the icosahedral particle. We demonstrate this with a simulation for the satellite tobacco necrosis virus (STNV), the atomic coordinates of whose asymmetric unit is given in Protein Data Bank entry 2BUK.

Photon-HDF5: An Open File Format for Timestamp-Based Single-Molecule Fluorescence Experiments

OpenAIRE

Ingargiola, Antonino; Laurence, Ted; Boutelle, Robert; Weiss, Shimon; Michalet, Xavier

2016-01-01

We introduce Photon-HDF5, an open and efficient file format to simplify exchange and long-term accessibility of data from single-molecule fluorescence experiments based on photon-counting detectors such as single-photon avalanche diode, photomultiplier tube, or arrays of such detectors. The format is based on HDF5, a widely used platform- and language-independent hierarchical file format for which user-friendly viewers are available. Photon-HDF5 can store raw photon data (timestamp, channel n...

Non-identical particle femtoscopy in models with single freeze-out

International Nuclear Information System (INIS)

Kisiel, Adam

2007-01-01

We present femtoscopic results from hydrodynamics-inspired thermal models with single freeze-out. Non-identical particle femtoscopy is studied and compared to results of identical particle correlations. Special emphasis is put on shifts between average space-time emission points of non-identical particles of different masses. They are found to be sensitive to both the spatial shift coming from radial flow, as well as average emission time difference coming from the resonance decays. The Terminator Monte-Carlo program was chosen for this study because it realistically models both of these effects. In order to analyze the results we present and test the methodology of non-identical particle correlations. (author)

Particle analysis and differentiation using a photovoltaic cell

International Nuclear Information System (INIS)

Fu, Lung-Ming; Shu, Wei-En; Wang, Yao-Nan

2012-01-01

A method is proposed for the sizing and counting of fluorescent and non-fluorescent particles of various sizes on a poly-dimethylsiloxane microchip. In the proposed approach, the detection region of the microchip is illuminated by a laser, which is then incident on a power-free photovoltaic cell. As the particles (both fluorescent and non-fluorescent) pass through the detection region, they block the laser beam, causing a reduction in the output voltage of the cell. The voltage signal is interfaced to a PC and is used to determine both the size and the number of the particles. Meanwhile, the fluorescence signal generated by the fluorescent particles within the sample is detected by an avalanche photodetector and is used to differentiate between the fluorescent and non-fluorescent particles in the sample. The effectiveness of the proposed approach is demonstrated using fluorescent-labeled beads with means diameters of 5, 8 and 10 µm, respectively, and unlabeled beads with a mean diameter of 7.2 µm. The experimental results confirm that the forward scattered light signal generated by the photovoltaic cell enables both the size and the number of the particles to be reliably determined. Moreover, it is shown that the number of non-fluorescent particles within the sample can be easily determined by comparing the signals received from the photovoltaic cell and avalanche photodetector, respectively. (paper)

Single-particle stochastic heat engine

Science.gov (United States)

Rana, Shubhashis; Pal, P. S.; Saha, Arnab; Jayannavar, A. M.

2014-10-01

We have performed an extensive analysis of a single-particle stochastic heat engine constructed by manipulating a Brownian particle in a time-dependent harmonic potential. The cycle consists of two isothermal steps at different temperatures and two adiabatic steps similar to that of a Carnot engine. The engine shows qualitative differences in inertial and overdamped regimes. All the thermodynamic quantities, including efficiency, exhibit strong fluctuations in a time periodic steady state. The fluctuations of stochastic efficiency dominate over the mean values even in the quasistatic regime. Interestingly, our system acts as an engine provided the temperature difference between the two reservoirs is greater than a finite critical value which in turn depends on the cycle time and other system parameters. This is supported by our analytical results carried out in the quasistatic regime. Our system works more reliably as an engine for large cycle times. By studying various model systems, we observe that the operational characteristics are model dependent. Our results clearly rule out any universal relation between efficiency at maximum power and temperature of the baths. We have also verified fluctuation relations for heat engines in time periodic steady state.

Temperature dependence of single-particle properties in nuclear matter

International Nuclear Information System (INIS)

Zuo, W.; Lu, G.C.; Li, Z.H.; Lombardo, U.; Schulze, H.-J.

2006-01-01

The single-nucleon potential in hot nuclear matter is investigated in the framework of the Brueckner theory by adopting the realistic Argonne V 18 or Nijmegen 93 two-body nucleon-nucleon interaction supplemented by a microscopic three-body force. The rearrangement contribution to the single-particle potential induced by the ground state correlations is calculated in terms of the hole-line expansion of the mass operator and provides a significant repulsive contribution in the low-momentum region around and below the Fermi surface. Increasing temperature leads to a reduction of the effect, while increasing density makes it become stronger. The three-body force suppresses somewhat the ground state correlations due to its strong short-range repulsion, increasing with density. Inclusion of the three-body force contribution results in a quite different temperature dependence of the single-particle potential at high enough densities as compared to that adopting the pure two-body force. The effects of three-body force and ground state correlations on the nucleon effective mass are also discussed

Double-slit experiment with single wave-driven particles and its relation to quantum mechanics.

Science.gov (United States)

Andersen, Anders; Madsen, Jacob; Reichelt, Christian; Rosenlund Ahl, Sonja; Lautrup, Benny; Ellegaard, Clive; Levinsen, Mogens T; Bohr, Tomas

2015-07-01

In a thought-provoking paper, Couder and Fort [Phys. Rev. Lett. 97, 154101 (2006)] describe a version of the famous double-slit experiment performed with droplets bouncing on a vertically vibrated fluid surface. In the experiment, an interference pattern in the single-particle statistics is found even though it is possible to determine unambiguously which slit the walking droplet passes. Here we argue, however, that the single-particle statistics in such an experiment will be fundamentally different from the single-particle statistics of quantum mechanics. Quantum mechanical interference takes place between different classical paths with precise amplitude and phase relations. In the double-slit experiment with walking droplets, these relations are lost since one of the paths is singled out by the droplet. To support our conclusions, we have carried out our own double-slit experiment, and our results, in particular the long and variable slit passage times of the droplets, cast strong doubt on the feasibility of the interference claimed by Couder and Fort. To understand theoretically the limitations of wave-driven particle systems as analogs to quantum mechanics, we introduce a Schrödinger equation with a source term originating from a localized particle that generates a wave while being simultaneously guided by it. We show that the ensuing particle-wave dynamics can capture some characteristics of quantum mechanics such as orbital quantization. However, the particle-wave dynamics can not reproduce quantum mechanics in general, and we show that the single-particle statistics for our model in a double-slit experiment with an additional splitter plate differs qualitatively from that of quantum mechanics.

Double-slit experiment with single wave-driven particles and its relation to quantum mechanics

Science.gov (United States)

Andersen, Anders; Madsen, Jacob; Reichelt, Christian; Rosenlund Ahl, Sonja; Lautrup, Benny; Ellegaard, Clive; Levinsen, Mogens T.; Bohr, Tomas

2015-07-01

In a thought-provoking paper, Couder and Fort [Phys. Rev. Lett. 97, 154101 (2006), 10.1103/PhysRevLett.97.154101] describe a version of the famous double-slit experiment performed with droplets bouncing on a vertically vibrated fluid surface. In the experiment, an interference pattern in the single-particle statistics is found even though it is possible to determine unambiguously which slit the walking droplet passes. Here we argue, however, that the single-particle statistics in such an experiment will be fundamentally different from the single-particle statistics of quantum mechanics. Quantum mechanical interference takes place between different classical paths with precise amplitude and phase relations. In the double-slit experiment with walking droplets, these relations are lost since one of the paths is singled out by the droplet. To support our conclusions, we have carried out our own double-slit experiment, and our results, in particular the long and variable slit passage times of the droplets, cast strong doubt on the feasibility of the interference claimed by Couder and Fort. To understand theoretically the limitations of wave-driven particle systems as analogs to quantum mechanics, we introduce a Schrödinger equation with a source term originating from a localized particle that generates a wave while being simultaneously guided by it. We show that the ensuing particle-wave dynamics can capture some characteristics of quantum mechanics such as orbital quantization. However, the particle-wave dynamics can not reproduce quantum mechanics in general, and we show that the single-particle statistics for our model in a double-slit experiment with an additional splitter plate differs qualitatively from that of quantum mechanics.

Dynamic fluorescence spectroscopy on single tryptophan mutants of EIImtl in detergent micelles : Effects of substrate binding and phosphorylation on the fluorescence and anisotropy decay

NARCIS (Netherlands)

Swaving Dijkstra, Dolf; Broos, J.; Visser, Antonie J.W.G.; van Hoek, A.; Robillard, George

1997-01-01

The effects of substrate and substrate analogue binding and phosphorylation on the conformational dynamics of the mannitol permease of Escherichia coli were investigated, using time-resolved fluorescence spectroscopy on mutants containing five single tryptophans situated in the membrane-embedded C

Chemical compositions of subway particles in Seoul, Korea determined by a quantitative single particle analysis.

Science.gov (United States)

Kang, Sunni; Hwang, HeeJin; Park, YooMyung; Kim, HyeKyoung; Ro, Chul-Un

2008-12-15

A novel single particle analytical technique, low-Z particle electron probe X-ray microanalysis, was applied to characterize seasonal subway samples collected at a subway station in Seoul, Korea. For all 8 samples collected twice in each season, 4 major types of subway particles, based on their chemical compositions, are significantly encountered: Fe-containing; soil-derived; carbonaceous; and secondary nitrate and/or sulfate particles. Fe-containing particles are generated indoors from wear processes at rail-wheel-brake interfaces while the others may be introduced mostly from the outdoor urban atmosphere. Fe-containing particles are the most frequently encountered with relative abundances in the range of 61-79%. In this study, it is shown that Fe-containing subway particles almost always exist either as partially or fully oxidized forms in underground subway microenvironments. Their relative abundances of Fe-containing particles increase as particle sizes decrease. Relative abundances of Fe-containing particles are higher in morning samples than in afternoon samples because of heavier train traffic in the morning. In the summertime samples, Fe-containing particles are the most abundantly encountered, whereas soil-derived and nitrate/sulfate particles are the least encountered, indicating the air-exchange between indoor and outdoor environments is limited in the summer, owing to the air-conditioning in the subway system. In our work, it was observed that the relative abundances of the particles of outdoor origin vary somewhat among seasonal samples to a lesser degree, reflecting that indoor emission sources predominate.

Damping of unbound single-particle modes

Energy Technology Data Exchange (ETDEWEB)

Fortier, S.; Beaumel, D.; Gales, S.; Guillot, J.; Langevin-Joliot, H.; Laurent, H.; Maison, J.M.; Bordewijk, J.; Brandenburg, S.; Krasznahorkay, A.; Crawley, G.M.; Massolo, C.P.; Renteria, M.; Khendriche, A. [Institut de Physique Nucleaire, IN2P3-CNRS, 91406 Orsay Cedex (France)]|[Kernfysisch Versneller Instituut, 9747 AA Groningen (Netherlands)]|[Nuclear Research Institute, Debrecen P.O. Box 51, H-4001 (Hungary)]|[NSCL, Michigan State University, East Lansing, Michigan 48824 (United States)]|[Dep. Fisica, Fac. Cs. Exactas, UNLP, CC Nio 67, 1900 La Plata (Argentina)]|[Institut de Sciences Exactes,Universite de Tizi-Ouzou, 15000 Tizi-Ouzou (Algeria)

1995-11-01

The ({alpha},{sup 3}He-{ital n}) reaction has been investigated at 120 MeV incident energy on {sup 64}Ni, {sup 90}Zr, and {sup 120}Sn target nuclei. Neutrons in coincidence with {sup 3}He particles emitted at 0{degree} were detected using the multidetector array EDEN, in order to get information about the decay of single-particle states embedded in the ({alpha},{sup 3}He) continuum. Neutron angular correlations, multiplicity values, and branching ratios to low-lying states of the final nuclei have been compared with the predictions of the statistical decay model. Evidence for a significant nonstatistical decay branch has been observed in the three nuclei below about 15 MeV excitation energy. Direct branching ratios in {sup 91}Zr deduced from this analysis are compared with the predictions of two nuclear structure models. At higher excitation energy, the decay characteristics of the ({alpha},{sup 3}He) continuum are shown to be mainly statistical.

Decay properties of high-lying single-particles modes

NARCIS (Netherlands)

Beaumel, D; Fortier, S; Gales, S; Guillot, J; LangevinJoliot, H; Laurent, H; Maison, JM; Vernotte, J; Bordewijck, J; Brandenburg, S; Krasznahorkay, A; Crawley, GM; Massolo, CP; Renteria, M; Khendriche, A

1996-01-01

The neutron decay of high-lying single-particle states in Ni-64, Zr-90, Sn-120 and (208)pb excited by means of the (alpha,He-3) reaction has been investigated at 120 MeV incident energy using the multidetector EDEN. The characteristics of this reaction are studied using inclusive spectra and angular

Determining Complex Structures using Docking Method with Single Particle Scattering Data

Directory of Open Access Journals (Sweden)

Haiguang Liu

2017-04-01

Full Text Available Protein complexes are critical for many molecular functions. Due to intrinsic flexibility and dynamics of complexes, their structures are more difficult to determine using conventional experimental methods, in contrast to individual subunits. One of the major challenges is the crystallization of protein complexes. Using X-ray free electron lasers (XFELs, it is possible to collect scattering signals from non-crystalline protein complexes, but data interpretation is more difficult because of unknown orientations. Here, we propose a hybrid approach to determine protein complex structures by combining XFEL single particle scattering data with computational docking methods. Using simulations data, we demonstrate that a small set of single particle scattering data collected at random orientations can be used to distinguish the native complex structure from the decoys generated using docking algorithms. The results also indicate that a small set of single particle scattering data is superior to spherically averaged intensity profile in distinguishing complex structures. Given the fact that XFEL experimental data are difficult to acquire and at low abundance, this hybrid approach should find wide applications in data interpretations.

Single particle and molecular assembly analysis of polyribosomes by single- and double-tilt cryo electron tomography

Energy Technology Data Exchange (ETDEWEB)

Myasnikov, Alexander G. [IGBMC (Institute of Genetics and of Molecular and Cellular Biology), Department of Integrative Structural Biology, Centre National de la Recherche Scientifique (CNRS) UMR 7104/ Institut National de la Santé de la Recherche Médicale INSERM U964/ Université de Strasbourg, 1 rue Laurent Fries, 67404 Illkirch (France); Afonina, Zhanna A. [Institute of Protein Research, Russian Academy of Sciences, 142290 Pushchino, Moscow Region (Russian Federation); Klaholz, Bruno P., E-mail: klaholz@igbmc.fr [IGBMC (Institute of Genetics and of Molecular and Cellular Biology), Department of Integrative Structural Biology, Centre National de la Recherche Scientifique (CNRS) UMR 7104/ Institut National de la Santé de la Recherche Médicale INSERM U964/ Université de Strasbourg, 1 rue Laurent Fries, 67404 Illkirch (France)

2013-03-15

Cryo electron tomography (cryo-ET) can provide cellular and molecular structural information on various biological samples. However, the detailed interpretation of tomograms reconstructed from single-tilt data tends to suffer from low signal-to-noise ratio and artefacts caused by some systematically missing angular views. While these can be overcome by sub-tomogram averaging, they remain limiting for the analysis of unique structures. Double-tilt ET can improve the tomogram quality by acquiring a second tilt series after an in-plane rotation, but its usage is not widespread yet because it is considered technically demanding and it is rarely used under cryo conditions. Here we show that double-tilt cryo-ET improves the quality of 3D reconstructions so significantly that even single particle analysis can be envisaged despite of the intrinsically low image contrast obtained from frozen-hydrated specimens. This is illustrated by the analysis of eukaryotic polyribosomes in which individual ribosomes were reconstructed using single-tilt, partial and full double-tilt geometries. The improved tomograms favour the faster convergence of iterative sub-tomogram averaging and allow a better 3D classification using multivariate statistical analysis. Our study of single particles and molecular assemblies within polysomes illustrates that the dual-axis approach is particularly useful for cryo applications of ET, both for unique objects and for structures that can be classified and averaged. - Highlights: ► Double-tilt cryo-ET improves 3D reconstructions thus making single particle analysis possible. ► Dual-axis cryo-ET data favour a faster convergence of iterative sub-tomogram averaging. ► Individual ribosomes were reconstructed from single-tilt, partial/ full double-tilt geometries. ► Double-tilt cryo-ET facilitates analysis of larger molecular assemblies such as in cell sections. ► Dual-axis cryo-ET is applicable to unique objects and to structures that can be

A new seniority scheme for non-degenerate single particle orbits

International Nuclear Information System (INIS)

Otsuka, T.; Arima, A.

1978-01-01

A new method is proposed in the treatment of the seniority scheme. The method enables one to evaluate analytically the contribution from J = 0 Cooper pairs in non-degenerate single-particle orbits to many-body matrix elements. It includes the SU(2) quasi-spin and the BCS approximation as two extreme limits. The effect of particle number conservation is properly taken into account. (Auth.)

Single-Particle States in $^{133}$Sn

CERN Multimedia

Huck, A

2002-01-01

% IS338 \\\\ \\\\ It is suggested to investigate the $\\beta^- $-decay of $^{133}$In and $^{134}$In in order to determine the single-particle states in $^{133}$Sn, which are so far unknown and needed for the shell-model description of the region close to $^{132}$Sn. Large hyper-pure Ge-detectors will be used for the $\\gamma$-ray spectroscopy. In the experiments with $^{134}$In, delayed neutrons in coincidence with $\\gamma$-rays from excited states in $^{133}$Sn provide the opportunity for a very selective detection of the states in question.

Single-particle characterization of urban aerosol particles collected in three Korean cites using low-Z electron probe X-ray microanalysis.

Science.gov (United States)

Ro, Chul-Un; Kim, HyeKyeong; Oh, Keun-Young; Yea, Sun Kyung; Lee, Chong Bum; Jang, Meongdo; Van Grieken, René

2002-11-15

A recently developed single-particle analytical technique, called low-Z electron probe X-ray microanalysis (low-Z EPMA), was applied to characterize urban aerosol particles collected in three cities of Korea (Seoul, CheongJu, and ChunCheon) on single days in the winter of 1999. In this study, it is clearly demonstrated that the low-Z EPMA technique can provide detailed and quantitative information on the chemical composition of particles in the urban atmosphere. The collected aerosol particles were analyzed and classified on the basis of their chemical species. Various types of particles were identified, such as soil-derived, carbonaceous, marine-originated, and anthropogenic particles. In the sample collected in Seoul, carbonaceous, aluminosilicates, silicon dioxide, and calcium carbonate aerosol particles were abundantly encountered. In the CheongJu and ChunCheon samples, carbonaceous, aluminosilicates, reacted sea salts, and ammonium sulfate aerosol particles were often seen. However, in the CheongJu sample, ammonium sulfate particles were the most abundant in the fine fraction. Also, calcium sulfate and nitrate particles were significantly observed. In the ChunCheon sample, organic particles were the most abundant in the fine fraction. Also, sodium nitrate particles were seen at high levels. The ChunCheon sample seemed to be strongly influenced by sea-salt aerosols originating from the Yellow Sea, which is located about 115 km away from the city.

Experimental Study on Effects of Particle Shape and Operating Conditions on Combustion Characteristics of Single Biomass Particles

DEFF Research Database (Denmark)

Momeni, M.; Yin, Chungen; Kær, Søren Knudsen

2013-01-01

An experimental study is performed to investigate the ignition, devolatilization, and burnout of single biomass particles of various shapes and sizes under process conditions that are similar to those in an industrial combustor. A chargecoupled device (CCD) camera is used to record the whole...... combustion process. For the particles with similar volume (mass), cylindrical particles are found to lose mass faster than spherical particles and the burnout time is shortened by increasing the particle aspect ratio (surface area). The conversion times of cylindrical particles with almost the same surface...... area/volume ratio are very close to each other. The ignition, devolatilization, and burnout times of cylindrical particles are also affected by the oxidizer temperature and oxygen concentration, in which the oxygen concentration is found to have a more pronounced effect on the conversion times at lower...

The single scattering properties of the aerosol particles as aggregated spheres

International Nuclear Information System (INIS)

Wu, Y.; Gu, X.; Cheng, T.; Xie, D.; Yu, T.; Chen, H.; Guo, J.

2012-01-01

The light scattering and absorption properties of anthropogenic aerosol particles such as soot aggregates are complicated in the temporal and spatial distribution, which introduce uncertainty of radiative forcing on global climate change. In order to study the single scattering properties of anthorpogenic aerosol particles, the structures of these aerosols such as soot paticles and soot-containing mixtures with the sulfate or organic matter, are simulated using the parallel diffusion limited aggregation algorithm (DLA) based on the transmission electron microscope images (TEM). Then, the single scattering properties of randomly oriented aerosols, such as scattering matrix, single scattering albedo (SSA), and asymmetry parameter (AP), are computed using the superposition T-matrix method. The comparisons of the single scattering properties of these specific types of clusters with different morphological and chemical factors such as fractal parameters, aspect ratio, monomer radius, mixture mode and refractive index, indicate that these different impact factors can respectively generate the significant influences on the single scattering properties of these aerosols. The results show that aspect ratio of circumscribed shape has relatively small effect on single scattering properties, for both differences of SSA and AP are less than 0.1. However, mixture modes of soot clusters with larger sulfate particles have remarkably important effects on the scattering and absorption properties of aggregated spheres, and SSA of those soot-containing mixtures are increased in proportion to the ratio of larger weakly absorbing attachments. Therefore, these complex aerosols come from man made pollution cannot be neglected in the aerosol retrievals. The study of the single scattering properties on these kinds of aggregated spheres is important and helpful in remote sensing observations and atmospheric radiation balance computations.

Force-activatable biosensor enables single platelet force mapping directly by fluorescence imaging.

Science.gov (United States)

Wang, Yongliang; LeVine, Dana N; Gannon, Margaret; Zhao, Yuanchang; Sarkar, Anwesha; Hoch, Bailey; Wang, Xuefeng

2018-02-15

Integrin-transmitted cellular forces are critical for platelet adhesion, activation, aggregation and contraction during hemostasis and thrombosis. Measuring and mapping single platelet forces are desired in both research and clinical applications. Conventional force-to-strain based cell traction force microscopies have low resolution which is not ideal for cellular force mapping in small platelets. To enable platelet force mapping with submicron resolution, we developed a force-activatable biosensor named integrative tension sensor (ITS) which directly converts molecular tensions to fluorescent signals, therefore enabling cellular force mapping directly by fluorescence imaging. With ITS, we mapped cellular forces in single platelets at 0.4µm resolution. We found that platelet force distribution has strong polarization which is sensitive to treatment with the anti-platelet drug tirofiban, suggesting that the ITS force map can report anti-platelet drug efficacy. The ITS also calibrated integrin molecular tensions in platelets and revealed two distinct tension levels: 12-54 piconewton (nominal values) tensions generated during platelet adhesion and tensions above 54 piconewton generated during platelet contraction. Overall, the ITS is a powerful biosensor for the study of platelet mechanobiology, and holds great potential in antithrombotic drug development and assessing platelet activity in health and disease. Copyright © 2017 Elsevier B.V. All rights reserved.

Digital atom interferometer with single particle control on a discretized space-time geometry.

Science.gov (United States)

Steffen, Andreas; Alberti, Andrea; Alt, Wolfgang; Belmechri, Noomen; Hild, Sebastian; Karski, Michał; Widera, Artur; Meschede, Dieter

2012-06-19

Engineering quantum particle systems, such as quantum simulators and quantum cellular automata, relies on full coherent control of quantum paths at the single particle level. Here we present an atom interferometer operating with single trapped atoms, where single particle wave packets are controlled through spin-dependent potentials. The interferometer is constructed from a sequence of discrete operations based on a set of elementary building blocks, which permit composing arbitrary interferometer geometries in a digital manner. We use this modularity to devise a space-time analogue of the well-known spin echo technique, yielding insight into decoherence mechanisms. We also demonstrate mesoscopic delocalization of single atoms with a separation-to-localization ratio exceeding 500; this result suggests their utilization beyond quantum logic applications as nano-resolution quantum probes in precision measurements, being able to measure potential gradients with precision 5 x 10(-4) in units of gravitational acceleration g.

Two rhodamine 6G derivative compounds: a structural and fluorescence single-crystal study.

Science.gov (United States)

Di Paolo, Matias; Bossi, Mariano L; Baggio, Ricardo; Suarez, Sebastián A

2016-10-01

The synthesis, characterization, structural analysis and fluorescence properties of two rhodamine 6G derivatives are described, namely a propargylamine derivative, 3',6'-bis(ethylamino)-2',7'-dimethyl-2-(methylcyanide)spiro[isoindole-1,9'-xanthen]-3(2H)-one (I), and a γ-aminobutyric acid (GABA) derivative, 3',6'-bis(ethylamino)-2',7'-dimethyl-3-oxospiro[isoindole-1,9'-xanthen]-2(3H)-yl)butyricacid (II). Both structures are compared with four similar ones from the Cambridge Structural Database (CSD), and the interactions involved in the stabilization are analyzed using the atoms in molecules (AIM) theory. Finally, a single-crystal in-situ reaction study is presented, carried out by fluorescence methods, which enabled the `opening' of the spirolactam ring in the solid phase.

Single particle characterization using a light scattering module coupled to a time-of-flight aerosol mass spectrometer

Science.gov (United States)

Cross, E. S.; Onasch, T. B.; Canagaratna, M.; Jayne, J. T.; Kimmel, J.; Yu, X.-Y.; Alexander, M. L.; Worsnop, D. R.; Davidovits, P.

2008-12-01

We present the first single particle results obtained using an Aerodyne time-of-flight aerosol mass spectrometer coupled with a light scattering module (LS-ToF-AMS). The instrument was deployed at the T1 ground site approximately 40 km northeast of the Mexico City Metropolitan Area (MCMA) as part of the MILAGRO field study in March of 2006. The instrument was operated as a standard AMS from 12-30 March, acquiring average chemical composition and size distributions for the ambient aerosol, and in single particle mode from 27-30 March. Over a 75-h sampling period, 12 853 single particle mass spectra were optically triggered, saved, and analyzed. The correlated optical and chemical detection allowed detailed examination of single particle collection and quantification within the LS-ToF-AMS. The single particle data enabled the mixing states of the ambient aerosol to be characterized within the context of the size-resolved ensemble chemical information. The particulate mixing states were examined as a function of sampling time and most of the particles were found to be internal mixtures containing many of the organic and inorganic species identified in the ensemble analysis. The single particle mass spectra were deconvolved, using techniques developed for ensemble AMS data analysis, into HOA, OOA, NH4NO3, (NH4)2SO4, and NH4Cl fractions. Average single particle mass and chemistry measurements are shown to be in agreement with ensemble MS and PTOF measurements. While a significant fraction of ambient particles were internal mixtures of varying degrees, single particle measurements of chemical composition allowed the identification of time periods during which the ambient ensemble was externally mixed. In some cases the chemical composition of the particles suggested a likely source. Throughout the full sampling period, the ambient ensemble was an external mixture of combustion-generated HOA particles from local sources (e.g. traffic), with number concentrations peaking

Dual fluorescence of single LH2 antenna nanorings

International Nuclear Information System (INIS)

Freiberg, A.; Raetsep, M.; Timpmann, K.; Trinkunas, G.

2004-01-01

A dual nature of fluorescence from LH2 pigment-protein complexes, which is a part of the light harvesting system of purple bacteria, is confirmed by fluorescence-lifetime dependence on recording wavelength and spectrally selective spectroscopy. An analysis based on the Holstein molecular crystal model, modified by allowing diagonal disorder, suggests coexistence of large- and small-radius self-trapped excitons, which serve as the origin of the dual fluorescence

Electrical trapping mechanism of single-microparticles in a pore sensor

Directory of Open Access Journals (Sweden)

Akihide Arima

2016-11-01

Full Text Available Nanopore sensing via resistive pulse technique are utilized as a potent tool to characterize physical and chemical property of single –molecules and –particles. In this article, we studied the influence of particle trajectory to the ionic conductance through a pore. We performed the optical/electrical simultaneous sensing of electrophoretic capture dynamics of single-particles at a pore using a microchannel/nanopore system. We detected ionic current drops synchronous to a fluorescently dyed particle being electrophoretically drawn and become immobilized at a pore in the optical imaging. We also identified anomalous trapping events wherein particles were captured at nanoscale pin-holes formed unintentionally in a SiN membrane that gave rise to relatively small current drops. This method is expected to be a useful platform for testing novel nanopore sensor design wherein current behaves in unpredictable manner.

Single-particle properties from Kohn-Sham Green's functions

International Nuclear Information System (INIS)

Bhattacharyya, Anirban; Furnstahl, R.J.

2005-01-01

An effective action approach to Kohn-Sham density functional theory is used to illustrate how the exact Green's function can be calculated in terms of the Kohn-Sham Green's function. An example based on Skyrme energy functionals shows that single-particle Kohn-Sham spectra can be improved by adding sources used to construct the energy functional

Fluorescent sensors based on bacterial fusion proteins

International Nuclear Information System (INIS)

Mateu, Batirtze Prats; Pum, Dietmar; Sleytr, Uwe B; Toca-Herrera, José L; Kainz, Birgit

2014-01-01

Fluorescence proteins are widely used as markers for biomedical and technological purposes. Therefore, the aim of this project was to create a fluorescent sensor, based in the green and cyan fluorescent protein, using bacterial S-layers proteins as scaffold for the fluorescent tag. We report the cloning, expression and purification of three S-layer fluorescent proteins: SgsE-EGFP, SgsE-ECFP and SgsE-13aa-ECFP, this last containing a 13-amino acid rigid linker. The pH dependence of the fluorescence intensity of the S-layer fusion proteins, monitored by fluorescence spectroscopy, showed that the ECFP tag was more stable than EGFP. Furthermore, the fluorescent fusion proteins were reassembled on silica particles modified with cationic and anionic polyelectrolytes. Zeta potential measurements confirmed the particle coatings and indicated their colloidal stability. Flow cytometry and fluorescence microscopy showed that the fluorescence of the fusion proteins was pH dependent and sensitive to the underlying polyelectrolyte coating. This might suggest that the fluorescent tag is not completely exposed to the bulk media as an independent moiety. Finally, it was found out that viscosity enhanced the fluorescence intensity of the three fluorescent S-layer proteins. (paper)

F F1-ATPase as biosensor to detect single virus

International Nuclear Information System (INIS)

Liu, XiaoLong; Zhang, Yun; Yue, JiaChang; Jiang, PeiDong; Zhang, ZhenXi

2006-01-01

F F 1 -ATPase within chromatophore was constructed as a biosensor (immuno-rotary biosensor) for the purpose of capturing single virus. Capture of virus was based on antibody-antigen reaction. The detection of virus based on proton flux change driven by ATP-synthesis of F F 1 -ATPase, which was indicated by F1300, was directly observed by a fluorescence microscope. The results demonstrate that the biosensor loading of virus particles has remarkable signal-to-noise ratio (3.8:1) compared to its control at single molecular level, and will be convenient, quick, and even super-sensitive for detecting virus particles

Single-label kinase and phosphatase assays for tyrosine phosphorylation using nanosecond time-resolved fluorescence detection.

Science.gov (United States)

Sahoo, Harekrushna; Hennig, Andreas; Florea, Mara; Roth, Doris; Enderle, Thilo; Nau, Werner M

2007-12-26

The collision-induced fluorescence quenching of a 2,3-diazabicyclo[2.2.2]oct-2-ene-labeled asparagine (Dbo) by hydrogen atom abstraction from the tyrosine residue in peptide substrates was introduced as a single-labeling strategy to assay the activity of tyrosine kinases and phosphatases. The assays were tested for 12 different combinations of Dbo-labeled substrates and with the enzymes p60c-Src Src kinase, EGFR kinase, YOP protein tyrosine phosphatase, as well as acid and alkaline phosphatases, thereby demonstrating a broad application potential. The steady-state fluorescence changed by a factor of up to 7 in the course of the enzymatic reaction, which allowed for a sufficient sensitivity of continuous monitoring in steady-state experiments. The fluorescence lifetimes (and intensities) were found to be rather constant for the phosphotyrosine peptides (ca. 300 ns in aerated water), while those of the unphosphorylated peptides were as short as 40 ns (at pH 7) and 7 ns (at pH 13) as a result of intramolecular quenching. Owing to the exceptionally long fluorescence lifetime of Dbo, the assays were alternatively performed by using nanosecond time-resolved fluorescence (Nano-TRF) detection, which leads to an improved discrimination of background fluorescence and an increased sensitivity. The potential for inhibitor screening was demonstrated through the inhibition of acid and alkaline phosphatases by molybdate.

Fluorescence Spectroscopy, Exciton Dynamics and Photochemistry of Single Allophycocyanin Trimers

International Nuclear Information System (INIS)

Ying, Liming; Xie, Xiaoliang

1998-01-01

We report a study of the spectroscopy and exciton dynamics of the allophycocyanin trimer (APC), a light harvesting protein complex from cyanobacteria, by room-temperature single-molecule measurements of fluorescence spectra, lifetimes, intensity trajectories and polarization modulation. Emission spectra of individual APC trimers are found to be homogeneous on the time scale of seconds. In contrast, their emission lifetimes are found to be widely distributed, because of generation of exciton traps during the course of measurements. The intensity trajectories and polarization modulation experiments indicate reversible ixciton trap formation within the three quasi-independent pairs of strong interacting a84 and B84 chromophores in APC, as well a photobleaching of individual chromophores. Comparison experiments under continuous wave and pulsed excitation reveal a two-photon mechanism for generating exciton traps and/or photobleaching, which involves exciton-exciton annihilation. These single-molecule experiments provide new insights into exciton dynamics and photochemistry of light-harvesting complexes

Controlled and tunable polymer particles' production using a single microfluidic device

Science.gov (United States)

Amoyav, Benzion; Benny, Ofra

2018-04-01

Microfluidics technology offers a new platform to control liquids under flow in small volumes. The advantage of using small-scale reactions for droplet generation along with the capacity to control the preparation parameters, making microfluidic chips an attractive technology for optimizing encapsulation formulations. However, one of the drawback in this methodology is the ability to obtain a wide range of droplet sizes, from sub-micron to microns using a single chip design. In fact, typically, droplet chips are used for micron-dimension particles, while nanoparticles' synthesis requires complex chips design (i.e., microreactors and staggered herringbone micromixer). Here, we introduce the development of a highly tunable and controlled encapsulation technique, using two polymer compositions, for generating particles ranging from microns to nano-size using the same simple single microfluidic chip design. Poly(lactic-co-glycolic acid) (PLGA 50:50) or PLGA/polyethylene glycol polymeric particles were prepared with focused-flow chip, yielding monodisperse particle batches. We show that by varying flow rate, solvent, surfactant and polymer composition, we were able to optimize particles' size and decrease polydispersity index, using simple chip designs with no further related adjustments or costs. Utilizing this platform, which offers tight tuning of particle properties, could offer an important tool for formulation development and can potentially pave the way towards a better precision nanomedicine.

High-Throughput Accurate Single-Cell Screening of Euglena gracilis with Fluorescence-Assisted Optofluidic Time-Stretch Microscopy.

Directory of Open Access Journals (Sweden)

Baoshan Guo

Full Text Available The development of reliable, sustainable, and economical sources of alternative fuels is an important, but challenging goal for the world. As an alternative to liquid fossil fuels, algal biofuel is expected to play a key role in alleviating global warming since algae absorb atmospheric CO2 via photosynthesis. Among various algae for fuel production, Euglena gracilis is an attractive microalgal species as it is known to produce wax ester (good for biodiesel and aviation fuel within lipid droplets. To date, while there exist many techniques for inducing microalgal cells to produce and accumulate lipid with high efficiency, few analytical methods are available for characterizing a population of such lipid-accumulated microalgae including E. gracilis with high throughout, high accuracy, and single-cell resolution simultaneously. Here we demonstrate high-throughput, high-accuracy, single-cell screening of E. gracilis with fluorescence-assisted optofluidic time-stretch microscopy-a method that combines the strengths of microfluidic cell focusing, optical time-stretch microscopy, and fluorescence detection used in conventional flow cytometry. Specifically, our fluorescence-assisted optofluidic time-stretch microscope consists of an optical time-stretch microscope and a fluorescence analyzer on top of a hydrodynamically focusing microfluidic device and can detect fluorescence from every E. gracilis cell in a population and simultaneously obtain its image with a high throughput of 10,000 cells/s. With the multi-dimensional information acquired by the system, we classify nitrogen-sufficient (ordinary and nitrogen-deficient (lipid-accumulated E. gracilis cells with a low false positive rate of 1.0%. This method holds promise for evaluating cultivation techniques and selective breeding for microalgae-based biofuel production.

Preliminary Understanding of Surface Plasmon-Enhanced Circular Dichroism Spectroscopy by Single Particle Imaging

Science.gov (United States)

Zhan, Kangshu

Monitoring chiral optical signals of biomolecules as their conformation changes is an important means to study their structures, properties, and functions. Most measurements, however, are ensemble measurements because chiral optical signals from a single biomolecule is often too weak to be detected. In this dissertation, I present my early attempts to study conformational changes of adsorbed proteins by taking advantage of the enhanced electromagnetic (EM) field around a well-designed plasmonic nanofeature. In particular, I discuss the detection of protein adsorption and denaturation on metallic nanoparticles using single particle scattering and CD spectroscopic imaging. Particles of two distinctively different sizes were compared and two different sample protein molecules were studied. A combination of experimental and computational tools was used to simulate and interpret the collected scattering and CD results. The first chapter provides a brief overview of the state-of-art research in CD spectroscopic studies at the single particle level. Three different means to make particles capable of chiral detection are discussed. Various applications beyond single particle imaging are presented to showcase the potential of the described research project, beyond our immediate goals. The second chapter describes my initial characterization of large, metallic, anisotropic nanorods and the establishment of experimental procedures used later for spectrum reconstruction, data visualization and analysis. The physical shape and structure of the particles were imaged by scanning electron microscopy (SEM), the chemical composition by energy dispersive X-ray Spectroscopy (EDS), and the optical properties by darkfield microscopy. An experimental protocol was developed to connect information collected from separate techniques for the same particle, with the aims of discovering any possible structural-property correlation. The reproducibility of the single particle imaging method was

Simulating Biomass Fast Pyrolysis at the Single Particle Scale

Energy Technology Data Exchange (ETDEWEB)

Ciesielski, Peter [National Renewable Energy Laboratory (NREL); Wiggins, Gavin [ORNL; Daw, C Stuart [ORNL; Jakes, Joseph E. [U.S. Forest Service, Forest Products Laboratory, Madison, Wisconsin, USA

2017-07-01

Simulating fast pyrolysis at the scale of single particles allows for the investigation of the impacts of feedstock-specific parameters such as particle size, shape, and species of origin. For this reason particle-scale modeling has emerged as an important tool for understanding how variations in feedstock properties affect the outcomes of pyrolysis processes. The origins of feedstock properties are largely dictated by the composition and hierarchical structure of biomass, from the microstructural porosity to the external morphology of milled particles. These properties may be accounted for in simulations of fast pyrolysis by several different computational approaches depending on the level of structural and chemical complexity included in the model. The predictive utility of particle-scale simulations of fast pyrolysis can still be enhanced substantially by advancements in several areas. Most notably, considerable progress would be facilitated by the development of pyrolysis kinetic schemes that are decoupled from transport phenomena, predict product evolution from whole-biomass with increased chemical speciation, and are still tractable with present-day computational resources.

Detection of ultra-low oxygen concentration based on the fluorescence blinking dynamics of single molecules

Science.gov (United States)

Wu, Ruixiang; Chen, Ruiyun; Zhou, Haitao; Qin, Yaqiang; Zhang, Guofeng; Qin, Chengbing; Gao, Yan; Gao, Yajun; Xiao, Liantuan; Jia, Suotang

2018-01-01

We present a sensitive method for detection of ultra-low oxygen concentrations based on the fluorescence blinking dynamics of single molecules. The relationship between the oxygen concentration and the fraction of time spent in the off-state, stemming from the population and depopulation of triplet states and radical cationic states, can be fitted with a two-site quenching model in the Stern-Volmer plot. The oxygen sensitivity is up to 43.42 kPa-1 in the oxygen partial pressure region as low as 0.01-0.25 kPa, which is seven times higher than that of the fluorescence intensity indicator. This method avoids the limitation of the sharp and non-ignorable fluctuations that occur during the measurement of fluorescence intensity, providing potential applications in the field of low oxygen-concentration monitoring in life science and industry.

Evaluation of Bacterivory of Rotifera Based on Measurements of in-Situ Ingestion of Fluorescent Particles, Including Some Comparisons with Cladocera

NARCIS (Netherlands)

Ooms-Wilms, A.L.; Postema, G.; Gulati, R.D.

1995-01-01

Bacterivory of pelagic rotifers and cladocerans in eutrophic Lake Loosdrecht (The Netherlands) was determined by microscopic observation of in situ tracer particle uptake. Ingestion rates of rotifer species using 0.51 mu m microspheres or fluorescently labelled bacteria as tracers differed, with one

Single particle aerosol mass spectrometry of coal combustion particles associated with high lung cancer rates in Xuanwei and Fuyuan, China.

Science.gov (United States)

Lu, Senlin; Tan, Zhengying; Liu, Pinwei; Zhao, Hui; Liu, Dingyu; Yu, Shang; Cheng, Ping; Win, Myat Sandar; Hu, Jiwen; Tian, Linwei; Wu, Minghong; Yonemochi, Shinich; Wang, Qingyue

2017-11-01

Coal combustion particles (CCPs) are linked to the high incidence of lung cancer in Xuanwei and in Fuyuan, China, but studies on the chemical composition of the CCPs are still limited. Single particle aerosol mass spectrometry (SPAMS) was recently developed to measure the chemical composition and size of single particles in real-time. In this study, SPAMS was used to measure individual combustion particles emitted from Xuanwei and Fuyuan coal samples and the results were compared with those by ICP-MS and transmission electron microscopy (TEM). The total of 38,372 particles mass-analyzed by SPAMS can be divided into 9 groups based on their chemical composition and their number percentages: carbonaceous, Na-rich, K-rich, Al-rich, Fe-rich, Si-rich, Ca-rich, heavy metal-bearing, and PAH-bearing particles. The carbonaceous and PAH-bearing particles are enriched in the size range below 0.56 μm, Fe-bearing particles range from 0.56 to 1.0 μm in size, and heavy metals such as Ti, V, Cr, Cu, Zn, and Pb have diameters below 1 μm. The TEM results show that the particles from Xuanwei and Fuyuan coal combustion can be classified into soot aggregates, Fe-rich particles, heavy metal containing particles, and mineral particles. Non-volatile particles detected by SPAMS could also be observed with TEM. The number percentages by SPAMS also correlate with the mass concentrations measured by ICP-MS. Our results could provide valuable insight for understanding high lung cancer incidence in the area. Copyright © 2017 Elsevier Ltd. All rights reserved.

Source characterization of urban particles from meat smoking activities in Chongqing, China using single particle aerosol mass spectrometry.

Science.gov (United States)

Chen, Yang; Wenger, John C; Yang, Fumo; Cao, Junji; Huang, Rujin; Shi, Guangming; Zhang, Shumin; Tian, Mi; Wang, Huanbo

2017-09-01

A Single Particle Aerosol Mass Spectrometer (SPAMS) was deployed in the urban area of Chongqing to characterize the particles present during a severe particulate pollution event that occurred in winter 2014-2015. The measurements were made at a time when residents engaged in traditional outdoor meat smoking activities to preserve meat before the Chinese Spring Festival. The measurement period was predominantly characterized by stagnant weather conditions, highly elevated levels of PM 2.5 , and low visibility. Eleven major single particle types were identified, with over 92.5% of the particles attributed to biomass burning emissions. Most of the particle types showed appreciable signs of aging in the stagnant air conditions. To simulate the meat smoking activities, a series of controlled smoldering experiments was conducted using freshly cut pine and cypress branches, both with and without wood logs. SPAMS data obtained from these experiments revealed a number of biomass burning particle types, including an elemental and organic carbon (ECOC) type that proved to be the most suitable marker for meat smoking activities. The traditional activity of making preserved meat in southwestern China is shown here to be a major source of particulate pollution. Improved measures to reduce emissions from the smoking of meat should be introduced to improve air quality in regions where smoking meat activity prevails. Copyright © 2017 Elsevier Ltd. All rights reserved.

Preparation and flow cytometry of uniform silica-fluorescent dye microspheres.

Science.gov (United States)

Bele, Marjan; Siiman, Olavi; Matijević, Egon

2002-10-15

Uniform fluorescent silica-dye microspheres have been prepared by coating preformed monodispersed silica particles with silica layers containing rhodamine 6G or acridine orange. The resulting dispersions exhibit intense fluorescent emission between 500 and 600 nm, over a broad excitation wavelength range of 460 to 550 nm, even with exceedingly small amounts of dyes incorporated into the silica particles (10-30 ppm, expressed as weight of dye relative to weight of dry particles). The fluorescent particles can be prepared in micrometer diameters suitable for analyses using flow cytometry with 488-nm laser excitation.

Development of a Charged Particle Microbeam for Single-Particle Subcellular Irradiations at the MIT Laboratory for Accelerator Beam Application

International Nuclear Information System (INIS)

Yanch, Jacquelyn C.

2004-01-01

The development of a charged particle microbeam for single particle, subcellular irradiations at the Massachusetts Institute of Technology Laboratory for Accelerator Beam Applications (MIT LABA) was initiated under this NEER aeard. The Microbeam apparatus makes use of a pre-existing electrostatic accelerator with a horizontal beam tube

Online single particle analysis of ice particle residuals from mountain-top mixed-phase clouds using laboratory derived particle type assignment

Science.gov (United States)

Schmidt, Susan; Schneider, Johannes; Klimach, Thomas; Mertes, Stephan; Schenk, Ludwig Paul; Kupiszewski, Piotr; Curtius, Joachim; Borrmann, Stephan

2017-01-01

In situ single particle analysis of ice particle residuals (IPRs) and out-of-cloud aerosol particles was conducted by means of laser ablation mass spectrometry during the intensive INUIT-JFJ/CLACE campaign at the high alpine research station Jungfraujoch (3580 m a.s.l.) in January-February 2013. During the 4-week campaign more than 70 000 out-of-cloud aerosol particles and 595 IPRs were analyzed covering a particle size diameter range from 100 nm to 3 µm. The IPRs were sampled during 273 h while the station was covered by mixed-phase clouds at ambient temperatures between -27 and -6 °C. The identification of particle types is based on laboratory studies of different types of biological, mineral and anthropogenic aerosol particles. The outcome of these laboratory studies was characteristic marker peaks for each investigated particle type. These marker peaks were applied to the field data. In the sampled IPRs we identified a larger number fraction of primary aerosol particles, like soil dust (13 ± 5 %) and minerals (11 ± 5 %), in comparison to out-of-cloud aerosol particles (2.4 ± 0.4 and 0.4 ± 0.1 %, respectively). Additionally, anthropogenic aerosol particles, such as particles from industrial emissions and lead-containing particles, were found to be more abundant in the IPRs than in the out-of-cloud aerosol. In the out-of-cloud aerosol we identified a large fraction of aged particles (31 ± 5 %), including organic material and secondary inorganics, whereas this particle type was much less abundant (2.7 ± 1.3 %) in the IPRs. In a selected subset of the data where a direct comparison between out-of-cloud aerosol particles and IPRs in air masses with similar origin was possible, a pronounced enhancement of biological particles was found in the IPRs.

Experimental study of single-particle inclusive hadron scattering and associated multiplicities

International Nuclear Information System (INIS)

Brenner, A.E.; Carey, D.C.; Elias, J.E.; Garbincius, P.H.; Mikenberg, G.; Polychronakos, V.A.; Aitkenhead, W.; Barton, D.S.; Brandenburg, G.W.; Busza, W.; Dobrowolski, T.; Friedman, J.I.; Kendall, H.W.; Lyons, T.; Nelson, B.; Rosenson, L.; Toy, W.; Verdier, R.; Votta, L.; Chiaradia, M.T.; DeMarzo, C.; Favuzzi, C.; Germinario, G.; Guerriero, L.; LaVopa, P.; Maggi, G.; Posa, F.; Selvaggi, G.; Spinelli, P.; Waldner, F.; Meunier, R.; Cutts, D.; Dulude, R.S.; Lanou, R.E. Jr.; Massimo, J.T.

1982-01-01

An experiment using the Fermilab single arm spectrometer (SAS) facility and an associated nonmagnetic vertex detector studied the reactions a+p→c+X where a and c were π +- , K +- , p, or p-bar. Extensive measurements were made at 100 and 175 GeV/c beam momenta with the outgoing hadrons detected in the SAS covering a kinematic range 0.12< x<1.0 and p/sub T/<1.25 GeV/c. Additional data covering a more restricted range in x were also gathered at 70 GeV/c incident momentum. In this high-statistics experiment, the identification of both the incoming and outgoing charged hadrons were made with a total of eight Cerenkov counters. New and extensive single-particle inclusive data for charged-particle production in low-p/sub T/ hadronic fragmentation are presented. The average associated charged-particle multiplicity and pseudorapidity distributions are also given

Characterization of iron speciation in urban and rural single particles using XANES spectroscopy and micro X-ray fluorescence measurements: investigating the relationship between speciation and fractional iron solubility

OpenAIRE

Oakes, M.; Weber, R. J.; Lai, B.; Russell, A.; Ingall, E. D.

2012-01-01

Soluble iron in fine atmospheric particles has been identified as a public health concern by participating in reactions that generate reactive oxygen species (ROS). The mineralogy and oxidation state (speciation) of iron have been shown to influence fractional iron solubility (soluble iron/total iron). In this study, iron speciation was determined in single particles at urban and rural sites in Georgia USA using synchrotron-based techniques, such as X-ray Absorption Near-Edge Structure (XANES...

Single molecule experiments challenge the strict wave-particle dualism of light.

Science.gov (United States)

Greulich, Karl Otto

2010-01-21

Single molecule techniques improve our understanding of the photon and light. If the single photon double slit experiment is performed at the "single photon limit" of a multi-atom light source, faint light pulses with more than one photon hamper the interpretation. Single molecules, quantum dots or defect centres in crystals should be used as light source. "Single photon detectors" do not meet their promise-only "photon number resolving single photon detectors" do so. Particularly, the accumulation time argument, the only safe basis for the postulate of a strictly particle like photon, has so far not yet been verified.

The chlorophyll a fluorescence induction pattern in chloroplasts upon repetitive single turnover excitations: Accumulation and function of QB-nonreducing centers

NARCIS (Netherlands)

Vredenberg, W.J.; Kasalicky, V.; Durchan, M.; Prasil, O.

2006-01-01

The increase of chlorophyll fluorescence yield in chloroplasts in a 12.5 Hz train of saturating single turnover flashes and the kinetics of fluorescence yield decay after the last flash have been analyzed. The approximate twofold increase in Fm relative to Fo, reached after 30-40 flashes, is

Characterization of nanostructures in the live cell plasma membrane utilizing advanced single molecule fluorescence techniques

International Nuclear Information System (INIS)

Brameshuber, M.

2009-01-01

Unrevealing the detailed structure of the cellular plasma membrane at a nanoscopic length scale is the key for understanding the regulation of various signaling pathways or interaction mechanism. Hypotheses postulate the existence of nanoscopic lipid platforms in the cell membrane which are termed lipid- or membrane rafts. Based on biochemical studies, rafts are believed to play a crucial role in many signaling processes. However, there is currently not much information on their size, shape, stability, surface density, composition and heterogeneity. In this thesis I present an ultra-sensitive fluorescence based method which allows for the first time the direct imaging of single mobile rafts in the live cell plasma membrane. The method senses rafts by their property to assemble a characteristic set of fluorescent marker-proteins or lipids on a time-scale of seconds. A special photobleaching protocol was developed and used to reduce the surface density of labeled mobile rafts down to the level of well-isolated diffraction-limited spots, without altering the single spot brightness. The statistical distribution of probe molecules per raft was determined by single molecule brightness analysis. For demonstration, I used the consensus markers Bodipy-GM1, a fluorescent lipid analogue, and glycosylphosphatidyl-inositol-anchored monomeric GFP. For both markers I found cholesterol-dependent association in the plasma membrane of living CHO and Jurkat T cells in the resting state, indicating the presence of mobile, stable rafts hosting these probes. I further characterized these structures by taking cell-to-cell variations under consideration. By comparing Bodipy-GM1 with mGFP-GPI homo-association upon temperature variation, two different states - a non-equilibrated and an equilibrated state - could be identified. I conclude that rafts are loaded non-randomly; the characteristic load is maintained during its lifetime in the plasma membrane of a non-activated cell. Beside these

Single-crystalline spherical β-Ga2O3 particles: Synthesis, N-doping and photoluminescence properties

International Nuclear Information System (INIS)

Zhang, Tingting; Lin, Jing; Zhang, Xinghua; Huang, Yang; Xu, Xuewen; Xue, Yanming; Zou, Jin; Tang, Chengchun

2013-01-01

We report on the synthesis of single-crystalline spherical β-Ga 2 O 3 particles by a simple method in ambient atmosphere. No pre-treatment, catalyst, substrate, or gas flow was required during the synthesis process. The well-dispersed Ga 2 O 3 particles display uniform spherical morphology with an average diameter of ∼200 nm. Photoluminescence studies indicate that the Ga 2 O 3 particles exhibit a broad blue-green light emission and an interesting red light emission at room temperature. The red light emission can be further tuned by post-annealing of the particles in ammonia atmosphere. The present single-crystalline β-Ga 2 O 3 particles with spherical morphology, uniform sub-micrometer sizes and tunable light emission are envisaged to be of high promise for applications in white-LED phosphors and optoelectronic devices. -- Highlights: ► We prepared single-crystalline spherical β-Ga 2 O 3 particles in ambient atmosphere. ► The particles display uniform spherical morphology with an average diameter of ∼200 nm. ► The Ga 2 O 3 particles exhibit a broad blue-green light and an interesting red light emission. ► The red light emission can be further tuned by post-annealing of the particles

Gold nanoparticle enhanced fluorescence anisotropy for the assay of single nucleotide polymorphisms (SNPs) based on toehold-mediated strand-displacement reaction.

Science.gov (United States)

Wang, Xinyi; Zou, Mingjian; Huang, Hongduan; Ren, Yuqian; Li, Limei; Yang, Xiaoda; Li, Na

2013-03-15

We developed a highly differentiating, homogeneous gold nanoparticle (AuNP) enhanced fluorescence anisotropic method for single nucleotide polymorphism (SNP) detection at nanomolar level using toehold-mediated strand-displacement reaction. The template strand, containing a toehold domain with an allele-specific site, was immobilized on the surface of AuNPs, and the solution fluorescence anisotropy was markedly enhanced when the fluorescein-labeled blocking DNA was attached to the AuNP via hybridization. Strand-displacement by the target ssDNA strand resulted in detachment of fluorescein-labeled DNA from AuNPs, and thus decreased fluorescence anisotropy. The drastic kinetic difference in strand-displacement from toehold design was used to distinguish between the perfectly matched and the single-base mismatched strands. Free energy changes were calculated to elucidate the dependence of the differentiation ability on the mutation site in the toehold region. A solid negative signal change can be obtained for single-base mismatched strand in the dynamic range of the calibration curve, and a more than 10-fold signal difference can still be observed in a mixed solution containing 100 times the single-base mismatched strand, indicating the good specificity of the method. This proposed method can be performed with a standard spectrofluorimeter in a homogeneous and cost-effective manner, and has the potential to be extended to the application of fluorescence anisotropy method of SNP detection. Copyright © 2012 Elsevier B.V. All rights reserved.

Effect of Surface Chemistry on the Fluorescence of Detonation Nanodiamonds.

Science.gov (United States)

Reineck, Philipp; Lau, Desmond W M; Wilson, Emma R; Fox, Kate; Field, Matthew R; Deeleepojananan, Cholaphan; Mochalin, Vadym N; Gibson, Brant C

2017-11-28

Detonation nanodiamonds (DNDs) have unique physical and chemical properties that make them invaluable in many applications. However, DNDs are generally assumed to show weak fluorescence, if any, unless chemically modified with organic molecules. We demonstrate that detonation nanodiamonds exhibit significant and excitation-wavelength-dependent fluorescence from the visible to the near-infrared spectral region above 800 nm, even without the engraftment of organic molecules to their surfaces. We show that this fluorescence depends on the surface functionality of the DND particles. The investigated functionalized DNDs, produced from the same purified DND as well as the as-received polyfunctional starting material, are hydrogen, hydroxyl, carboxyl, ethylenediamine, and octadecylamine-terminated. All DNDs are investigated in solution and on a silicon wafer substrate and compared to fluorescent high-pressure high-temperature nanodiamonds. The brightest fluorescence is observed from octadecylamine-functionalized particles and is more than 100 times brighter than the least fluorescent particles, carboxylated DNDs. The majority of photons emitted by all particle types likely originates from non-diamond carbon. However, we locally find bright and photostable fluorescence from nitrogen-vacancy centers in diamond in hydrogenated, hydroxylated, and carboxylated detonation nanodiamonds. Our results contribute to understanding the effects of surface chemistry on the fluorescence of DNDs and enable the exploration of the fluorescent properties of DNDs for applications in theranostics as nontoxic fluorescent labels, sensors, nanoscale tracers, and many others where chemically stable and brightly fluorescent nanoparticles with tailorable surface chemistry are needed.

Integrated Transmission Electron and Single‐Molecule Fluorescence Microscopy Correlates Reactivity with Ultrastructure in a Single Catalyst Particle

OpenAIRE

Hendriks, Frank C.; Mohammadian, Sajjad; Ristanović, Zoran; Kalirai, Sam; Meirer, Florian; Vogt, Eelco T. C.; Bruijnincx, Pieter C. A.; Gerritsen, Hans C.; Weckhuysen, Bert M.

2017-01-01

Abstract Establishing structure–activity relationships in complex, hierarchically structured nanomaterials, such as fluid catalytic cracking (FCC) catalysts, requires characterization with complementary, correlated analysis techniques. An integrated setup has been developed to perform transmission electron microscopy (TEM) and single‐molecule fluorescence (SMF) microscopy on such nanostructured samples. Correlated structure–reactivity information was obtained for 100 nm thin, microtomed secti...

Recent Progress on Plasmon-Enhanced Fluorescence

Directory of Open Access Journals (Sweden)

Dong Jun

2015-12-01

Full Text Available The optically generated collective electron density waves on metal–dielectric boundaries known as surface plasmons have been of great scientific interest since their discovery. Being electromagnetic waves on gold or silver nanoparticle’s surface, localised surface plasmons (LSP can strongly enhance the electromagnetic field. These strong electromagnetic fields near the metal surfaces have been used in various applications like surface enhanced spectroscopy (SES, plasmonic lithography, plasmonic trapping of particles, and plasmonic catalysis. Resonant coupling of LSPs to fluorophore can strongly enhance the emission intensity, the angular distribution, and the polarisation of the emitted radiation and even the speed of radiative decay, which is so-called plasmon enhanced fluorescence (PEF. As a result, more and more reports on surface-enhanced fluorescence have appeared, such as SPASER-s, plasmon assisted lasing, single molecule fluorescence measurements, surface plasmoncoupled emission (SPCE in biological sensing, optical orbit designs etc. In this review, we focus on recent advanced reports on plasmon-enhanced fluorescence (PEF. First, the mechanism of PEF and early results of enhanced fluorescence observed by metal nanostructure will be introduced. Then, the enhanced substrates, including periodical and nonperiodical nanostructure, will be discussed and the most important factor of the spacer between molecule and surface and wavelength dependence on PEF is demonstrated. Finally, the recent progress of tipenhanced fluorescence and PEF from the rare-earth doped up-conversion (UC and down-conversion (DC nanoparticles (NPs are also commented upon. This review provides an introduction to fundamentals of PEF, illustrates the current progress in the design of metallic nanostructures for efficient fluorescence signal amplification that utilises propagating and localised surface plasmons.

Characterizing physical properties and heterogeneous chemistry of single particles in air using optical trapping-Raman spectroscopy

Science.gov (United States)

Gong, Z.; Wang, C.; Pan, Y. L.; Videen, G.

2017-12-01

Heterogeneous reactions of solid particles in a gaseous environment are of increasing interest; however, most of the heterogeneous chemistry studies of airborne solids were conducted on particle ensembles. A close examination on the heterogeneous chemistry between single particles and gaseous-environment species is the key to elucidate the fundamental mechanisms of hydroscopic growth, cloud nuclei condensation, secondary aerosol formation, etc., and reduce the uncertainty of models in radiative forcing, climate change, and atmospheric chemistry. We demonstrate an optical trapping-Raman spectroscopy (OT-RS) system to study the heterogeneous chemistry of the solid particles in air at single-particle level. Compared to other single-particle techniques, optical trapping offers a non-invasive, flexible, and stable method to isolate single solid particle from substrates. Benefited from two counter-propagating hollow beams, the optical trapping configuration is adaptive to trap a variety of particles with different materials from inorganic substitution (carbon nanotubes, silica, etc.) to organic, dye-doped polymers and bioaerosols (spores, pollen, etc.), with different optical properties from transparent to strongly absorbing, with different sizes from sub-micrometers to tens of microns, or with distinct morphologies from loosely packed nanotubes to microspheres and irregular pollen grains. The particles in the optical trap may stay unchanged, surface degraded, or optically fragmented according to different laser intensity, and their physical and chemical properties are characterized by the Raman spectra and imaging system simultaneously. The Raman spectra is able to distinguish the chemical compositions of different particles, while the synchronized imaging system can resolve their physical properties (sizes, shapes, morphologies, etc.). The temporal behavior of the trapped particles also can be monitored by the OT-RS system at an indefinite time with a resolution from

Single-cell-based evaluation of sperm progressive motility via fluorescent assessment of mitochondria membrane potential.

Science.gov (United States)

Moscatelli, Natalina; Spagnolo, Barbara; Pisanello, Marco; Lemma, Enrico Domenico; De Vittorio, Massimo; Zara, Vincenzo; Pisanello, Ferruccio; Ferramosca, Alessandra

2017-12-20

Sperm cells progressive motility is the most important parameter involved in the fertilization process. Sperm middle piece contains mitochondria, which play a critical role in energy production and whose proper operation ensures the reproductive success. Notably, sperm progressive motility is strictly related to mitochondrial membrane potential (MMP) and consequently to mitochondrial functionality. Although previous studies presented an evaluation of mitochondrial function through MMP assessment in entire sperm cells samples, a quantitative approach at single-cell level could provide more insights in the analysis of semen quality. Here we combine laser scanning confocal microscopy and functional fluorescent staining of mitochondrial membrane to assess MMP distribution among isolated spermatozoa. We found that the sperm fluorescence value increases as a function of growing progressive motility and that such fluorescence is influenced by MMP disruptors, potentially allowing for the discrimination of different quality classes of sperm cells in heterogeneous populations.

Particles Produced in Association with High Transverse Momentum Single Photons and $\\pi^0$s in Hadronic Collision

Energy Technology Data Exchange (ETDEWEB)

Sinanidis, Alexandros Pericles [Northeastern U.

1989-01-01

The charged and neutral particles produced in association with high transverse momentum ($Pr_{\\tau}$ > 5.0 GeV /c) photons ($\\gamma$) and neutral pions ($\\pi^0$) in p(Cu+Be) and $\\pi^-$(cu+Be) collisions at vs = 31.5 GeV are studied in this thesis. It was observed that 1) The relative rapidity of the two highest Pr recoiling particles in the events have a jet - like structure. 2) The relative rapidity of the single $\\gamma$ (or $\\pi^0$ ) and the highest $P_{\\tau}$ charged particle accompanying the single $\\gamma$ (or $\\pi^0$ ) show that the high $P_{\\tau} \\pi^0$ events have a jet - like structure in the trigger hemisphere whereas the high $P_{\\tau}$ single $\\gamma$ events do not. 3) The angular distributions of the particles produced in the reactions show that high $P_{\\tau} \\pi^0$s are accompanied by other particles, whereas high $P_{\\tau}$ single photons are relatively isolated. 4) The fragmentation distributions of the recoiling particles from the high $P_{\\tau}$ single photons and $\\pi^0$s are consistent with the measurements of other experiments. 5) The recoiling particles are consistent with the fragmentation of either a quark or a gluon according to the QCD (Quantum Chromodynamics). In summary, particles produced in association with high transverse momentum single photons and $\\pi^0$s in hadronic collisions have been measured and their properties are in good agreement with the predictions of the parton model and those of QCD

A database of microwave and sub-millimetre ice particle single scattering properties

Science.gov (United States)

Ekelund, Robin; Eriksson, Patrick

2016-04-01

Ice crystal particles are today a large contributing factor as to why cold-type clouds such as cirrus remain a large uncertainty in global climate models and measurements. The reason for this is the complex and varied morphology in which ice particles appear, as compared to liquid droplets with an in general spheroidal shape, thus making the description of electromagnetic properties of ice particles more complicated. Single scattering properties of frozen hydrometers have traditionally been approximated by representing the particles as spheres using Mie theory. While such practices may work well in radio applications, where the size parameter of the particles is generally low, comparisons with measurements and simulations show that this assumption is insufficient when observing tropospheric cloud ice in the microwave or sub-millimetre regions. In order to assist the radiative transfer and remote sensing communities, a database of single scattering properties of semi-realistic particles is being produced. The data is being produced using DDA (Discrete Dipole Approximation) code which can treat arbitrarily shaped particles, and Tmatrix code for simpler shapes when found sufficiently accurate. The aim has been to mainly cover frequencies used by the upcoming ICI (Ice Cloud Imager) mission with launch in 2022. Examples of particles to be included are columns, plates, bullet rosettes, sector snowflakes and aggregates. The idea is to treat particles with good average optical properties with respect to the multitude of particles and aggregate types appearing in nature. The database will initially only cover macroscopically isotropic orientation, but will eventually also include horizontally aligned particles. Databases of DDA particles do already exist with varying accessibility. The goal of this database is to complement existing data. Regarding the distribution of the data, the plan is that the database shall be available in conjunction with the ARTS (Atmospheric

Single charging events on colloidal particles in a nonpolar liquid with surfactant

Science.gov (United States)

Schreuer, Caspar; Vandewiele, Stijn; Brans, Toon; Strubbe, Filip; Neyts, Kristiaan; Beunis, Filip

2018-01-01

Electrical charging of colloidal particles in nonpolar liquids due to surfactant additives is investigated intensively, motivated by its importance in a variety of applications. Most methods rely on average electrophoretic mobility measurements of many particles, which provide only indirect information on the charging mechanism. In the present work, we present a method that allows us to obtain direct information on the charging mechanism, by measuring the charge fluctuations on individual particles with a precision higher than the elementary charge using optical trapping electrophoresis. We demonstrate the capabilities of the method by studying the influence of added surfactant OLOA 11000 on the charging of single colloidal PMMA particles in dodecane. The particle charge and the frequency of charging events are investigated both below and above the critical micelle concentration (CMC) and with or without applying a DC offset voltage. It is found that at least two separate charging mechanisms are present below the critical micelle concentration. One mechanism is a process where the particle is stripped from negatively charged ionic molecules. An increase in the charging frequency with increased surfactant concentration suggests a second mechanism that involves single surfactant molecules. Above the CMC, neutral inverse micelles can also be involved in the charging process.

Probing Single Nanometer-scale Particles with Scanning Tunneling Microscopy and Spectroscopies

International Nuclear Information System (INIS)

McCarty, G.S.; Love, J.C.; Kushmerick, J.G.; Charles, L.F.; Keating, C.D.; Toleno, B.J.; Lyn, M.E.; Castleman, A.W.; Natan, M.J.; Weiss, P.S.

1999-01-01

Scanning tunneling microscopy can be used to isolate single particles on surfaces for further study. Local optical and electronic properties coupled with topographic information collected by the scanning tunneling microscope (STM) give insight into the intrinsic properties of the species under study. Since each spectroscopic measurement is done on a single particle, each sample is 'monodisperse', regardless of the degree of heterogeneity of the original preparation. We illustrate this with three example systems - a metal cluster of known atomic structure, metal nanoparticles dispersed from colloid suspensions, and metallocarbohedrenes (Met-Cars) deposited with other reaction products. Au and Ag nanoparticles were imaged using a photon emission STM. The threshold voltage, the lowest bias voltage at which photons are produced, was determined for Au nanoparticles. Electronic spectra of small clusters of Ni atoms on MoS 2 were recorded. Preliminary images of Zr-based Met-Car-containing soot were obtained on Au and MoS 2 substrates and partial electronic spectra were recorded of these possible Met-Car particles

Building the Nanoplasmonics Toolbox Through Shape Modeling and Single Particle Optical Studies

Science.gov (United States)

Ringe, Emilie

Interest in nanotechnology is driven by unprecedented properties tailorability, achievable by controlling particle structure and composition. Unlike bulk components, minute changes in size and shape affect the optical and electronic properties of nanoparticles. Characterization of such structure-function relationships and better understanding of structure control mechanisms is crucial to the development of applications such as plasmonic sensors and devices. The objective of the current research is thus twofold: to theoretically predict and understand how shape is controlled by synthesis conditions, and to experimentally unravel, through single particle studies, how shape, composition, size, and surrounding environment affect plasmonic properties in noble metal particles. Quantitative, predictive rules and fundamental knowledge obtained from this research contributes to the "nanoplasmonics toolbox", a library designed to provide scientists and engineers the tools to create and optimize novel nanotechnology applications. In this dissertation, single particle approaches are developed and used to unravel the effects of size, shape, substrate, aggregation state and surrounding environment on the optical response of metallic nanoparticles. Ag and Au nanocubes on different substrates are first presented, followed by the discussion of the concept of plasmon length, a universal parameter to describe plasmon energy for a variety of particle shapes and plasmon modes. Plasmonic sensing (both refractive index sensing and surface-enhanced Raman spectroscopy) and polarization effects are then studied at the single particle level. In the last two Chapters, analytical shape models based on the Wulff construction provide unique modeling tools for alloy and kinetically grown nanoparticles. The former reveals a size-dependence of the shape of small alloy particles (such as those used in catalysis) because of surface segregation, while the latter uniquely models the shape of many

Magnetization Reversal Process of Single Crystal α-Fe Containing a Nonmagnetic Particle

International Nuclear Information System (INIS)

Li Yi; Xu Ben; Li Qiu-Lin; Liu Wei; Hu Shen-Yang; Li Yu-Lan

2015-01-01

The magnetization reversal process and hysteresis loops in a single crystal α-iron with nonmagnetic particles are simulated in this work based on the Landau—Lifshitz—Gilbert equation. The evolutions of the magnetic domain morphology are studied, and our analyses show that the magnetization reversal process is affected by the interaction between the moving domain wall and the existing nonmagnetic particles. This interaction strongly depends on the size of the particles, and it is found that particles with a particular size contribute the most to magnetic hardening. (paper)

Development of windows based software to analyze fluorescence decay with time-correlated single photon counting (TCSPC) setup

International Nuclear Information System (INIS)

Mallick, M.B.; Ravindranath, S.V.G.; Das, N.C.

2002-07-01

A VUV spectroscopic facility for studies in photophysics and photochemistry is being set up at INDUS-I synchrotron source, CAT, Indore. For this purpose, a data acquisition system based on time-correlated single photon counting method is being developed for fluorescence lifetime measurement. To estimate fluorescence lifetime from the data collected with this sytem, a Windows based program has been developed using Visual Basic 5.0. It uses instrument response function (IRF) and observed decay curve and estimates parameters of single exponential decay by least square analysis and Marquardt method as convergence mechanism. Estimation of parameters was performed using data collected with a commercial setup. Goodness of fit was judged by evaluating χR 2 , weighted residuals and autocorrelation function. Performance is compared with two commercial software packages and found to be satisfactory. (author)

Single Molecule Experiments Challenge the Strict Wave-Particle Dualism of Light

Directory of Open Access Journals (Sweden)

Karl Otto Greulich

2010-01-01

Full Text Available Single molecule techniques improve our understanding of the photon and light. If the single photon double slit experiment is performed at the “single photon limit” of a multi-atom light source, faint light pulses with more than one photon hamper the interpretation. Single molecules, quantum dots or defect centres in crystals should be used as light source. “Single photon detectors” do not meet their promise―only “photon number resolving single photon detectors” do so. Particularly, the accumulation time argument, the only safe basis for the postulate of a strictly particle like photon, has so far not yet been verified.

Generally Applicable Transformation Protocols for Fluorescent Nanodiamond Internalization into Cells.

Science.gov (United States)

Hemelaar, Simon R; van der Laan, Kiran J; Hinterding, Sophie R; Koot, Manon V; Ellermann, Else; Perona-Martinez, Felipe P; Roig, David; Hommelet, Severin; Novarina, Daniele; Takahashi, Hiroki; Chang, Michael; Schirhagl, Romana

2017-07-19

Fluorescent nanodiamonds (FNDs) are promising nanoprobes, owing to their stable and magnetosensitive fluorescence. Therefore they can probe properties as magnetic resonances, pressure, temperature or strain. The unprecedented sensitivity of diamond defects can detect the faint magnetic resonance of a single electron or even a few nuclear spins. However, these sensitivities are only achieved if the diamond probe is close to the molecules that need to be detected. In order to utilize its full potential for biological applications, the diamond particle has to enter the cell. Some model systems, like HeLa cells, readily ingest particles. However, most cells do not show this behavior. In this article we show for the first time generally applicable methods, which are able to transport fluorescent nanodiamonds into cells with a thick cell wall. Yeast cells, in particular Saccharomyces cerevisiae, are a favored model organism to study intracellular processes including aging on a cellular level. In order to introduce FNDs in these cells, we evaluated electrical transformation and conditions of chemical permeabilization for uptake efficiency and viability. 5% DMSO (dimethyl sulfoxide) in combination with optimized chemical transformation mix leads to high uptake efficiency in combination with low impact on cell biology. We have evaluated all steps in the procedure.

Single-particle Analyses of Compositions, Morphology, and Viscosity of Aerosol Particles Collected During GoAmazon2014

Science.gov (United States)

Adachi, K.; Gong, Z.; Bateman, A. P.; Martin, S. T.; Cirino, G. G.; Artaxo, P.; Sedlacek, A. J., III; Buseck, P. R.

2014-12-01

Single-particle analysis using transmission electron microscopy (TEM) shows composition and morphology of individual aerosol particles collected during the GoAmazon2014 campaign. These TEM results indicate aerosol types and mixing states, both of which are important for evaluating particle optical properties and cloud condensation nuclei activity. The samples were collected at the T3 site, which is located in the Amazon forest with influences from the urban pollution plume from Manaus. Samples were also collected from the T0 site, which is in the middle of the jungle with minimal to no influences of anthropogenic sources. The aerosol particles mainly originated from 1) anthropogenic pollution (e.g., nanosphere soot, sulfate), 2) biogenic emissions (e.g., primary biogenic particles, organic aerosols), and 3) long-range transport (e.g., sea salts). We found that the biogenic organic aerosol particles contain homogeneously distributed potassium. Particle viscosity is important for evaluating gas-particle interactions and atmospheric chemistry for the particles. Viscosity can be estimated from the rebounding behavior at controlled relative humidities, i.e., highly viscous particles display less rebound on a plate than low-viscosity particles. We collected 1) aerosol particles from a plate (non-rebounded), 2) those that had rebounded from the plate and were then captured onto an adjacent sampling plate, and 3) particles from ambient air using a separate impactor sampler. Preliminary results show that more than 90% of non-rebounded particles consisted of nanosphere soot with or without coatings. The coatings mostly consisted of organic matter. Although rebounded particles also contain nanosphere soot (number fraction 64-69%), they were mostly internally mixed with sulfate, organic matter, or their mixtures. TEM tilted images suggested that the rebounded particles were less deformed on the substrate, whereas the non-rebounded particles were more deformed, which could

Analysis of photon count data from single-molecule fluorescence experiments

Science.gov (United States)

Burzykowski, T.; Szubiakowski, J.; Rydén, T.

2003-03-01

We consider single-molecule fluorescence experiments with data in the form of counts of photons registered over multiple time-intervals. Based on the observation schemes, linking back to works by Dehmelt [Bull. Am. Phys. Soc. 20 (1975) 60] and Cook and Kimble [Phys. Rev. Lett. 54 (1985) 1023], we propose an analytical approach to the data based on the theory of Markov-modulated Poisson processes (MMPP). In particular, we consider maximum-likelihood estimation. The method is illustrated using a real-life dataset. Additionally, the properties of the proposed method are investigated through simulations and compared to two other approaches developed by Yip et al. [J. Phys. Chem. A 102 (1998) 7564] and Molski [Chem. Phys. Lett. 324 (2000) 301].

Basic Evidence and Properties of Single-Particle States in Nuclei

Energy Technology Data Exchange (ETDEWEB)

Cindro, N. [Institute ' ' Rudjer Boskovic' ' , Zagreb, Yugoslavia (Croatia)

1970-07-15

1. Introduction: the shell-model orbitals; 2. Information about single-particle orbitals: a critical evaluation; 3. Experimental evidence: 3.1. The lead region; 3.2. The calcium region; 3.3. Nuclei far from closed shells; 4. Conclusion. (author)

Quantitative determination of carbonaceous particle mixing state in Paris using single particle mass spectrometer and aerosol mass spectrometer measurements

Science.gov (United States)

Healy, R. M.; Sciare, J.; Poulain, L.; Crippa, M.; Wiedensohler, A.; Prévôt, A. S. H.; Baltensperger, U.; Sarda-Estève, R.; McGuire, M. L.; Jeong, C.-H.; McGillicuddy, E.; O'Connor, I. P.; Sodeau, J. R.; Evans, G. J.; Wenger, J. C.

2013-04-01

Single particle mixing state information can be a powerful tool for assessing the relative impact of local and regional sources of ambient particulate matter in urban environments. However, quantitative mixing state data are challenging to obtain using single particle mass spectrometers. In this study, the quantitative chemical composition of carbonaceous single particles has been estimated using an aerosol time-of-flight mass spectrometer (ATOFMS) as part of the MEGAPOLI 2010 winter campaign in Paris, France. Relative peak areas of marker ions for elemental carbon (EC), organic aerosol (OA), ammonium, nitrate, sulphate and potassium were compared with concurrent measurements from an Aerodyne high resolution time-of-flight aerosol mass spectrometer (HR-ToF-AMS), a thermal/optical OCEC analyser and a particle into liquid sampler coupled with ion chromatography (PILS-IC). ATOFMS-derived mass concentrations reproduced the variability of these species well (R2 = 0.67-0.78), and ten discrete mixing states for carbonaceous particles were identified and quantified. Potassium content was used to identify particles associated with biomass combustion. The chemical mixing state of HR-ToF-AMS organic aerosol factors, resolved using positive matrix factorization, was also investigated through comparison with the ATOFMS dataset. The results indicate that hydrocarbon-like OA (HOA) detected in Paris is associated with two EC-rich mixing states which differ in their relative sulphate content, while fresh biomass burning OA (BBOA) is associated with two mixing states which differ significantly in their OA/EC ratios. Aged biomass burning OA (OOA2-BBOA) was found to be significantly internally mixed with nitrate, while secondary, oxidized OA (OOA) was associated with five particle mixing states, each exhibiting different relative secondary inorganic ion content. Externally mixed secondary organic aerosol was not observed. These findings demonstrate the heterogeneity of primary and

Source apportionment of aerosol particles using polycapillary slightly focusing X-ray lens

Energy Technology Data Exchange (ETDEWEB)

Sun Tianxi [Key Laboratory of Beam Technology and Materials Modification of Ministry of Education, Beijing Normal University, Beijing 100875 (China) and Institute of Low Energy Nuclear Physics, Beijing Normal University, Beijing 100875 (China) and Beijing Radiation Center, Beijing 100875 (China)], E-mail: stxbeijing@163.com; Liu Zhiguo [Key Laboratory of Beam Technology and Materials Modification of Ministry of Education, Beijing Normal University, Beijing 100875 (China) and Institute of Low Energy Nuclear Physics, Beijing Normal University, Beijing 100875 (China) and Beijing Radiation Center, Beijing 100875 (China)], E-mail: liuzgbeijing@163.com; Zhu Guanghua; Liu Hui [Key Laboratory of Beam Technology and Materials Modification of Ministry of Education, Beijing Normal University, Beijing 100875 (China); Institute of Low Energy Nuclear Physics, Beijing Normal University, Beijing 100875 (China); Beijing Radiation Center, Beijing 100875 (China); Ma Yongzhong [Center for Disease Control and Prevention of Beijing, Beijing 100013 (China); Xu Qing [Institute of High Energy Physics, Chinese Academy of Science, Beijing 100039 (China); Li Yude; Wang Guangpu; Luo Ping; Pan Qiuli; Ding Xunliang [Key Laboratory of Beam Technology and Materials Modification of Ministry of Education, Beijing Normal University, Beijing 100875 (China); Institute of Low Energy Nuclear Physics, Beijing Normal University, Beijing 100875 (China); Beijing Radiation Center, Beijing 100875 (China)

2009-06-11

A micro-X-ray fluorescence (Micro-XRF) spectrometer based on a polycapillary slightly focusing X-ray lens (PSFXRL) and laboratory X-ray source was designed to carry out the source apportionment of aerosol particles. In the distribution curve of the X-ray intensity in the focal spot of PSFXRL, there was a plateau with a diameter of about 65 {mu}m. The uniformity of this plateau was about 3%. This was helpful in measuring the XRF spectrum of a single aerosol particle in which the element distributions are not uniform. The minimum detection limit (MDL) of this Micro-XRF spectrometer was 15 ppm for the Fe-K{sub {alpha}}. The origins of the aerosol particles at the exit of a subway station and a construction site were apportioned. This Micro-XRF spectrometer has potential applications in analysis of single aerosol particles.

Phase-coexistence simulations of fluid mixtures by the Markov Chain Monte Carlo method using single-particle models

KAUST Repository

Li, Jun

2013-09-01

We present a single-particle Lennard-Jones (L-J) model for CO2 and N2. Simplified L-J models for other small polyatomic molecules can be obtained following the methodology described herein. The phase-coexistence diagrams of single-component systems computed using the proposed single-particle models for CO2 and N2 agree well with experimental data over a wide range of temperatures. These diagrams are computed using the Markov Chain Monte Carlo method based on the Gibbs-NVT ensemble. This good agreement validates the proposed simplified models. That is, with properly selected parameters, the single-particle models have similar accuracy in predicting gas-phase properties as more complex, state-of-the-art molecular models. To further test these single-particle models, three binary mixtures of CH4, CO2 and N2 are studied using a Gibbs-NPT ensemble. These results are compared against experimental data over a wide range of pressures. The single-particle model has similar accuracy in the gas phase as traditional models although its deviation in the liquid phase is greater. Since the single-particle model reduces the particle number and avoids the time-consuming Ewald summation used to evaluate Coulomb interactions, the proposed model improves the computational efficiency significantly, particularly in the case of high liquid density where the acceptance rate of the particle-swap trial move increases. We compare, at constant temperature and pressure, the Gibbs-NPT and Gibbs-NVT ensembles to analyze their performance differences and results consistency. As theoretically predicted, the agreement between the simulations implies that Gibbs-NVT can be used to validate Gibbs-NPT predictions when experimental data is not available. © 2013 Elsevier Inc.

Ergodicity of a single particle confined in a nanopore

DEFF Research Database (Denmark)

Bernardi, S.; Hansen, Jesper Schmidt; Frascolli, F.

2012-01-01

-ergodic component of the phase space for energy levels typical of experiments, is surprisingly small, i.e. we conclude that the ergodic hypothesis is a reasonable approximation even for a single particle trapped in a nanopore. Due to the numerical scope of this work, our focus will be the onset of ergodic behavior...

The fluorescence properties of aerosol larger than 0.8 μm in urban and tropical rainforest locations

Science.gov (United States)

Gabey, A. M.; Stanley, W. R.; Gallagher, M. W.; Kaye, P. H.

2011-06-01

UV-LIF measurements were performed on ambient aerosol in Manchester, UK (urban city centre, winter) and Borneo, Malaysia (remote, tropical) using a Wide Issue Bioaerosol Spectrometer, version 3 (WIBS3). These sites are taken to represent environments with minor and significant primary biological aerosol (PBA) influences respectively, and the urban dataset describes the fluorescent background aerosol against which PBA must be identified by researchers using LIF. The ensemble aerosol at both sites was characterised over 2-3 weeks by measuring the fluorescence intensity and optical equivalent diameter (DP) of single particles sized 0.8 ≤ DP ≤ 20 μm. Filter samples were also collected for a subset of the Manchester campaign and analysed using energy dispersive X-Ray (EDX) spectroscopy and environmental scanning electron microscopy (ESEM), which revealed mostly non-PBA at D ≤ 1 μm. The WIBS3 features three fluorescence channels: the emission following a 280 nm excitation is recorded at 310-400 nm (channel F1) and 400-600 nm (F2), and fluorescence excited at 350 nm is detected at 400-600 nm (F3). In Manchester the primary size mode of fluorescent and non-fluorescent material was present at 0.8-1.2 μm, with a secondary fluorescent mode at 2-4 μm. In Borneo non-fluorescent material peaked at 0.8-1.2 μm and fluorescent at 3-4 μm. Agreement between fluorescent number concentrations in each channel differed at the two sites, with F1 and F3 reporting similar concentrations in Borneo but F3 outnumbering F1 by a factor of 2-3 across the size spectrum in Manchester. The fluorescence intensity in each channel generally rose with DP at both sites with the exception of F1 intensity in Manchester, which peaked at DP = 4 μm, causing a divergence between F1 and F3 intensity at larger DP. This divergence and the differing fluorescent particle concentrations demonstrate the additional discrimination provided by the F1 channel in Manchester. The relationships between

Improving surface and defect center chemistry of fluorescent nanodiamonds for imaging purposes--a review.

Science.gov (United States)

Nagl, Andreas; Hemelaar, Simon Robert; Schirhagl, Romana

2015-10-01

Diamonds are widely used for jewelry owing to their superior optical properties accounting for their fascinating beauty. Beyond the sparkle, diamond is highly investigated in materials science for its remarkable properties. Recently, fluorescent defects in diamond, particularly the negatively charged nitrogen-vacancy (NV(-)) center, have gained much attention: The NV(-) center emits stable, nonbleaching fluorescence, and thus could be utilized in biolabeling, as a light source, or as a Förster resonance energy transfer donor. Even more remarkable are its spin properties: with the fluorescence intensity of the NV(-) center reacting to the presence of small magnetic fields, it can be utilized as a sensor for magnetic fields as small as the field of a single electron spin. However, a reproducible defect and surface and defect chemistry are crucial to all applications. In this article we review methods for using nanodiamonds for different imaging purposes. The article covers (1) dispersion of particles, (2) surface cleaning, (3) particle size selection and reduction, (4) defect properties, and (5) functionalization and attachment to nanostructures, e.g., scanning probe microscopy tips.

Single particle inclusive spectra resulting from the collision of relativistic protons, deuterons, alpha particles, and carbon ions with nuclei

International Nuclear Information System (INIS)

Papp, J.

1975-05-01

The yields of positive and negative particles resulting from the collision of 1.05 GeV/nucleon and 2.1 GeV/nucleon protons, deuterons, alpha particles, and 1.05 GeV/nucleon carbon nuclei with various targets have been measured. Single particle inclusive cross sections for production of π + , π - , p, d, 3 H, 3 He, and 4 He at 2.5 0 (lab) were obtained. How the results bear on the concepts of limiting fragmentation and scaling, the structure of the alpha particle and deuteron, and the possibility of ''coherent'' production of pions by heavy ions are discussed. (U.S.)

Lipid diffusion in the distal and proximal leaflets of supported lipid bilayer membranes studied by single particle tracking

Science.gov (United States)

Schoch, Rafael L.; Barel, Itay; Brown, Frank L. H.; Haran, Gilad

2018-03-01

Supported lipid bilayers (SLBs) have been studied extensively as simple but powerful models for cellular membranes. Yet, potential differences in the dynamics of the two leaflets of a SLB remain poorly understood. Here, using single particle tracking, we obtain a detailed picture of bilayer dynamics. We observe two clearly separate diffusing populations, fast and slow, that we associate with motion in the distal and proximal leaflets of the SLB, respectively, based on fluorescence quenching experiments. We estimate diffusion coefficients using standard techniques as well as a new method based on the blur of images due to motion. Fitting the observed diffusion coefficients to a two-leaflet membrane hydrodynamic model allows for the simultaneous determination of the intermonolayer friction coefficient and the substrate-membrane friction coefficient, without any prior assumptions on the strengths of the relevant interactions. Remarkably, our calculations suggest that the viscosity of the interfacial water confined between the membrane and the substrate is elevated by ˜104 as compared to bulk water. Using hidden Markov model analysis, we then obtain insight into the transbilayer movement of lipids. We find that lipid flip-flop dynamics are very fast, with half times in the range of seconds. Importantly, we find little evidence for membrane defect mediated lipid flip-flop for SLBs at temperatures well above the solid-to-liquid transition, though defects seem to be involved when the SLBs are cooled down. Our work thus shows that the combination of single particle tracking and advanced hydrodynamic modeling provides a powerful means to obtain insight into membrane dynamics.

Quantification of protein based on single-molecule counting by total internal reflection fluorescence microscopy with adsorption equilibrium

International Nuclear Information System (INIS)

Wang Lei; Xu Guang; Shi Zhikun; Jiang Wei; Jin Wenrui

2007-01-01

We developed a sensitive single-molecule imaging method for quantification of protein by total internal reflection fluorescence microscopy with adsorption equilibrium. In this method, the adsorption equilibrium of protein was achieved between solution and glass substrate. Then, fluorescence images of protein molecules in a evanescent wave field were taken by a highly sensitive electron multiplying charge coupled device. Finally, the number of fluorescent spots corresponding to the protein molecules in the images was counted. Alexa Fluor 488-labeled goat anti-rat IgG(H + L) was chosen as the model protein. The spot number showed an excellent linear relationship with protein concentration. The concentration linear range was 5.4 x 10 -11 to 8.1 x 10 -10 mol L -1

Understanding particle size and distance driven competition of interparticle interactions and effective single-particle anisotropy

Czech Academy of Sciences Publication Activity Database

Pacáková, Barbara; Mantlíková, Alice; Nižňanský, D.; Kubíčková, Simona; Vejpravová, Jana

2016-01-01

Roč. 28, č. 20 (2016), 1-11, č. článku 206004. ISSN 0953-8984 R&D Projects: GA ČR(CZ) GA15-01953S Institutional support: RVO:68378271 Keywords : magnetic nanoparticles * single-particle anisotropy * dipolar energy Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 2.649, year: 2016

Optimal noise reduction in 3D reconstructions of single particles using a volume-normalized filter

Science.gov (United States)

Sindelar, Charles V.; Grigorieff, Nikolaus

2012-01-01

The high noise level found in single-particle electron cryo-microscopy (cryo-EM) image data presents a special challenge for three-dimensional (3D) reconstruction of the imaged molecules. The spectral signal-to-noise ratio (SSNR) and related Fourier shell correlation (FSC) functions are commonly used to assess and mitigate the noise-generated error in the reconstruction. Calculation of the SSNR and FSC usually includes the noise in the solvent region surrounding the particle and therefore does not accurately reflect the signal in the particle density itself. Here we show that the SSNR in a reconstructed 3D particle map is linearly proportional to the fractional volume occupied by the particle. Using this relationship, we devise a novel filter (the “single-particle Wiener filter”) to minimize the error in a reconstructed particle map, if the particle volume is known. Moreover, we show how to approximate this filter even when the volume of the particle is not known, by optimizing the signal within a representative interior region of the particle. We show that the new filter improves on previously proposed error-reduction schemes, including the conventional Wiener filter as well as figure-of-merit weighting, and quantify the relationship between all of these methods by theoretical analysis as well as numeric evaluation of both simulated and experimentally collected data. The single-particle Wiener filter is applicable across a broad range of existing 3D reconstruction techniques, but is particularly well suited to the Fourier inversion method, leading to an efficient and accurate implementation. PMID:22613568

Inequivalence of single-particle and population lifetimes in a cuprate superconductor

Energy Technology Data Exchange (ETDEWEB)

Yang, Shuolong [SLAC National Accelerator Lab., Menlo Park, CA (United States); Stanford Univ., Stanford, CA (United States); Sobota, J. A. [SLAC National Accelerator Lab., Menlo Park, CA (United States); Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States); Leuenberger, D. [SLAC National Accelerator Lab., Menlo Park, CA (United States); Stanford Univ., Stanford, CA (United States); He, Y. [SLAC National Accelerator Lab., Menlo Park, CA (United States); Stanford Univ., Stanford, CA (United States); Hashimoto, M. [SLAC National Accelerator Lab., Menlo Park, CA (United States); Lu, D. H. [SLAC National Accelerator Lab., Menlo Park, CA (United States); Eisaki, H. [National Institute of Advanced Industrial Science and Technology, Ibaraki (Japan); Kirchmann, P. S. [SLAC National Accelerator Lab., Menlo Park, CA (United States); Shen, Z. -X. [SLAC National Accelerator Lab., Menlo Park, CA (United States); Stanford Univ., Stanford, CA (United States)

2015-06-15

We study optimally doped Bi-2212 (T_c=96 K) using femtosecond time- and angle-resolved photoelectron spectroscopy. Energy-resolved population lifetimes are extracted and compared with single-particle lifetimes measured by equilibrium photoemission. The population lifetimes deviate from the single-particle lifetimes in the low excitation limit by 1–2 orders of magnitude. Fundamental considerations of electron scattering unveil that these two lifetimes are in general distinct, yet for systems with only electron-phonon scattering they should converge in the low-temperature, low-fluence limit. As a result, the qualitative disparity in our data, even in this limit, suggests that scattering channels beyond electron-phonon interactions play a significant role in the electron dynamics of cuprate superconductors.

Single-particle model of a strongly driven, dense, nanoscale quantum ensemble

Science.gov (United States)

DiLoreto, C. S.; Rangan, C.

2018-01-01

We study the effects of interatomic interactions on the quantum dynamics of a dense, nanoscale, atomic ensemble driven by a strong electromagnetic field. We use a self-consistent, mean-field technique based on the pseudospectral time-domain method and a full, three-directional basis to solve the coupled Maxwell-Liouville equations. We find that interatomic interactions generate a decoherence in the state of an ensemble on a much faster time scale than the excited-state lifetime of individual atoms. We present a single-particle model of the driven, dense ensemble by incorporating interactions into a dephasing rate. This single-particle model reproduces the essential physics of the full simulation and is an efficient way of rapidly estimating the collective dynamics of a dense ensemble.

Single-Particle Spin-Orbit Splittings in Nuclei

OpenAIRE

Kazuhiko, ANDO; Hiroharu, BANDO; Department of Physics, Kyoto University; Division of Mathematical Physics, Fukui University

1981-01-01

Single-particle spin-orbit splittings (Δ^) in ^O and ^Ca nuclei are evaluated within the framework of the effective interaction theory by employing the Reid soft-core potential and meson-exchange three-body forces (TBF). Among the two-body force contributions, the Pauli-rearrangement effect on Δ^ is studied with special care. The TBF contribution to Δ^ is found to be significant. The G-matrix, the second-order pauli-rearrangement and the TBF contribute to Δ^ by the amount of ～1/2, ～1/5 and ～1...

A dark-field microscope for background-free detection of resonance fluorescence from single semiconductor quantum dots operating in a set-and-forget mode.

Science.gov (United States)

Kuhlmann, Andreas V; Houel, Julien; Brunner, Daniel; Ludwig, Arne; Reuter, Dirk; Wieck, Andreas D; Warburton, Richard J

2013-07-01

Optically active quantum dots, for instance self-assembled InGaAs quantum dots, are potentially excellent single photon sources. The fidelity of the single photons is much improved using resonant rather than non-resonant excitation. With resonant excitation, the challenge is to distinguish between resonance fluorescence and scattered laser light. We have met this challenge by creating a polarization-based dark-field microscope to measure the resonance fluorescence from a single quantum dot at low temperature. We achieve a suppression of the scattered laser exceeding a factor of 10(7) and background-free detection of resonance fluorescence. The same optical setup operates over the entire quantum dot emission range (920-980 nm) and also in high magnetic fields. The major development is the outstanding long-term stability: once the dark-field point has been established, the microscope operates for days without alignment. The mechanical and optical designs of the microscope are presented, as well as exemplary resonance fluorescence spectroscopy results on individual quantum dots to underline the microscope's excellent performance.

A dark-field microscope for background-free detection of resonance fluorescence from single semiconductor quantum dots operating in a set-and-forget mode

International Nuclear Information System (INIS)

Kuhlmann, Andreas V.; Houel, Julien; Warburton, Richard J.; Brunner, Daniel; Ludwig, Arne; Reuter, Dirk; Wieck, Andreas D.

2013-01-01

Optically active quantum dots, for instance self-assembled InGaAs quantum dots, are potentially excellent single photon sources. The fidelity of the single photons is much improved using resonant rather than non-resonant excitation. With resonant excitation, the challenge is to distinguish between resonance fluorescence and scattered laser light. We have met this challenge by creating a polarization-based dark-field microscope to measure the resonance fluorescence from a single quantum dot at low temperature. We achieve a suppression of the scattered laser exceeding a factor of 10 7 and background-free detection of resonance fluorescence. The same optical setup operates over the entire quantum dot emission range (920–980 nm) and also in high magnetic fields. The major development is the outstanding long-term stability: once the dark-field point has been established, the microscope operates for days without alignment. The mechanical and optical designs of the microscope are presented, as well as exemplary resonance fluorescence spectroscopy results on individual quantum dots to underline the microscope's excellent performance

Mass Spectrometry of Single Particles Levitated in an Electrodynamic Balance: Applications to Laboratory Atmospheric Chemistry Research

Science.gov (United States)

Birdsall, A.; Krieger, U. K.; Keutsch, F. N.

2017-12-01

Dynamic changes to atmospheric aerosol particle composition (e.g., originating from evaporation/condensation, oxidative aging, or aqueous-phase chemical reactions) impact particle properties with importance for understanding particle effects on climate and human health. These changes can take place over the entire lifetime of an atmospheric particle, which can extend over multiple days. Previous laboratory studies of such processes have included analyzing single particles suspended in a levitation device, such as an electrodynamic balance (EDB), an optical levitator, or an acoustic trap, using optical detection techniques. However, studying chemically complex systems can require an analytical method, such as mass spectrometry, that provides more molecular specificity. Existing work coupling particle levitation with mass spectrometry is more limited and largely has consisted of acoustic levitation of millimeter-sized droplets.In this work an EDB has been coupled with a custom-built ionization source and commercial time-of-flight mass spectrometer (MS) as a platform for laboratory atmospheric chemistry research. Single charged particles (radius 10 μm) have been injected into an EDB, levitated for an arbitrarily long period of time, and then transferred to a vaporization-corona discharge ionization region for MS analysis. By analyzing a series of particles of identical composition, residing in the controlled environment of the EDB for varying times, we can trace the chemical evolution of a particle over hours or days, appropriate timescales for understanding transformations of atmospheric particles.To prove the concept of our EDB-MS system, we have studied the evaporation of particles consisting of polyethylene glycol (PEG) molecules of mixed chain lengths, used as a benchmark system. Our system can quantify the composition of single particles (see Figure for sample spectrum of a single PEG-200 particle: PEG parent ions labeled with m/z, known PEG fragment ions

Conversion of Beckman DK-2A spectrophotometer into an automatic single-photon counting fluorescence spectrophotometer

International Nuclear Information System (INIS)

Chikkur, G.C.; Lagare, M.T.; Umakantha, N.

1981-01-01

Details of how a DK-2A spectrophotometer can be modified into an automatic single-photon counting fluorescence spectrophotometer for recording a low intensity spectrum, are reported. The single-photon count-rate converted into a DC voltage is applied at the appropriate stage in the sample channel amplifier circuit of a DK-2A to get the pen deflection proportional to the count-rate. A high intensity spectrum may be recorded in the usual way by merely turning the shaft of the mirror motor by 180 degrees. (author)

Single pulse two photon fluorescence lifetime imaging (SP-FLIM) with MHz pixel rate.

Science.gov (United States)

Eibl, Matthias; Karpf, Sebastian; Weng, Daniel; Hakert, Hubertus; Pfeiffer, Tom; Kolb, Jan Philip; Huber, Robert

2017-07-01

Two-photon-excited fluorescence lifetime imaging microscopy (FLIM) is a chemically specific 3-D sensing modality providing valuable information about the microstructure, composition and function of a sample. However, a more widespread application of this technique is hindered by the need for a sophisticated ultra-short pulse laser source and by speed limitations of current FLIM detection systems. To overcome these limitations, we combined a robust sub-nanosecond fiber laser as the excitation source with high analog bandwidth detection. Due to the long pulse length in our configuration, more fluorescence photons are generated per pulse, which allows us to derive the lifetime with a single excitation pulse only. In this paper, we show high quality FLIM images acquired at a pixel rate of 1 MHz. This approach is a promising candidate for an easy-to-use and benchtop FLIM system to make this technique available to a wider research community.

Quantitative determination of carbonaceous particle mixing state in Paris using single-particle mass spectrometer and aerosol mass spectrometer measurements

Directory of Open Access Journals (Sweden)

R. M. Healy

2013-09-01

Full Text Available Single-particle mixing state information can be a powerful tool for assessing the relative impact of local and regional sources of ambient particulate matter in urban environments. However, quantitative mixing state data are challenging to obtain using single-particle mass spectrometers. In this study, the quantitative chemical composition of carbonaceous single particles has been determined using an aerosol time-of-flight mass spectrometer (ATOFMS as part of the MEGAPOLI 2010 winter campaign in Paris, France. Relative peak areas of marker ions for elemental carbon (EC, organic aerosol (OA, ammonium, nitrate, sulfate and potassium were compared with concurrent measurements from an Aerodyne high-resolution time-of-flight aerosol mass spectrometer (HR-ToF-AMS, a thermal–optical OCEC analyser and a particle into liquid sampler coupled with ion chromatography (PILS-IC. ATOFMS-derived estimated mass concentrations reproduced the variability of these species well (R2 = 0.67–0.78, and 10 discrete mixing states for carbonaceous particles were identified and quantified. The chemical mixing state of HR-ToF-AMS organic aerosol factors, resolved using positive matrix factorisation, was also investigated through comparison with the ATOFMS dataset. The results indicate that hydrocarbon-like OA (HOA detected in Paris is associated with two EC-rich mixing states which differ in their relative sulfate content, while fresh biomass burning OA (BBOA is associated with two mixing states which differ significantly in their OA / EC ratios. Aged biomass burning OA (OOA2-BBOA was found to be significantly internally mixed with nitrate, while secondary, oxidised OA (OOA was associated with five particle mixing states, each exhibiting different relative secondary inorganic ion content. Externally mixed secondary organic aerosol was not observed. These findings demonstrate the range of primary and secondary organic aerosol mixing states in Paris. Examination of the

Quantitative determination of carbonaceous particle mixing state in Paris using single-particle mass spectrometer and aerosol mass spectrometer measurements

Science.gov (United States)

Healy, R. M.; Sciare, J.; Poulain, L.; Crippa, M.; Wiedensohler, A.; Prévôt, A. S. H.; Baltensperger, U.; Sarda-Estève, R.; McGuire, M. L.; Jeong, C.-H.; McGillicuddy, E.; O'Connor, I. P.; Sodeau, J. R.; Evans, G. J.; Wenger, J. C.

2013-09-01

Single-particle mixing state information can be a powerful tool for assessing the relative impact of local and regional sources of ambient particulate matter in urban environments. However, quantitative mixing state data are challenging to obtain using single-particle mass spectrometers. In this study, the quantitative chemical composition of carbonaceous single particles has been determined using an aerosol time-of-flight mass spectrometer (ATOFMS) as part of the MEGAPOLI 2010 winter campaign in Paris, France. Relative peak areas of marker ions for elemental carbon (EC), organic aerosol (OA), ammonium, nitrate, sulfate and potassium were compared with concurrent measurements from an Aerodyne high-resolution time-of-flight aerosol mass spectrometer (HR-ToF-AMS), a thermal-optical OCEC analyser and a particle into liquid sampler coupled with ion chromatography (PILS-IC). ATOFMS-derived estimated mass concentrations reproduced the variability of these species well (R2 = 0.67-0.78), and 10 discrete mixing states for carbonaceous particles were identified and quantified. The chemical mixing state of HR-ToF-AMS organic aerosol factors, resolved using positive matrix factorisation, was also investigated through comparison with the ATOFMS dataset. The results indicate that hydrocarbon-like OA (HOA) detected in Paris is associated with two EC-rich mixing states which differ in their relative sulfate content, while fresh biomass burning OA (BBOA) is associated with two mixing states which differ significantly in their OA / EC ratios. Aged biomass burning OA (OOA2-BBOA) was found to be significantly internally mixed with nitrate, while secondary, oxidised OA (OOA) was associated with five particle mixing states, each exhibiting different relative secondary inorganic ion content. Externally mixed secondary organic aerosol was not observed. These findings demonstrate the range of primary and secondary organic aerosol mixing states in Paris. Examination of the temporal

Characterizing uranium oxide reference particles for isotopic abundances and uranium mass by single particle isotope dilution mass spectrometry

International Nuclear Information System (INIS)

Kraiem, M.; Richter, S.; Erdmann, N.; Kühn, H.; Hedberg, M.; Aregbe, Y.

2012-01-01

Highlights: ► A method to quantify the U mass in single micron particles by ID-TIMS was developed. ► Well-characterized monodisperse U-oxide particles produced by an aerosol generator were used. ► A linear correlation between the mass of U and the volume of particle(s) was found. ► The method developed is suitable for determining the amount of U in a particulate reference material. - Abstract: Uranium and plutonium particulate test materials are becoming increasingly important as the reliability of measurement results has to be demonstrated to regulatory bodies responsible for maintaining effective nuclear safeguards. In order to address this issue, the Institute for Reference Materials and Measurements (IRMM) in collaboration with the Institute for Transuranium Elements (ITU) has initiated a study to investigate the feasibility of preparing and characterizing a uranium particle reference material for nuclear safeguards, which is finally certified for isotopic abundances and for the uranium mass per particle. Such control particles are specifically required to evaluate responses of instruments based on mass spectrometric detection (e.g. SIMS, TIMS, LA-ICPMS) and to help ensuring the reliability and comparability of measurement results worldwide. In this paper, a methodology is described which allows quantifying the uranium mass in single micron particles by isotope dilution thermal ionization mass spectrometry (ID-TIMS). This methodology is characterized by substantial improvements recently achieved at IRMM in terms of sensitivity and measurement accuracy in the field of uranium particle analysis by TIMS. The use of monodisperse uranium oxide particles prepared using an aerosol generation technique developed at ITU, which is capable of producing particles of well-characterized size and isotopic composition was exploited. The evidence of a straightforward correlation between the particle volume and the mass of uranium was demonstrated in this study

Fluorescent boronic acid terminated polymer grafted silica particles synthesized via click chemistry for affinity separation of saccharides

Energy Technology Data Exchange (ETDEWEB)

Xu, Zhifeng, E-mail: 897061147@qq.com; Deng, Peihong; Tang, Siping; Li, Junhua

2014-07-01

Boronic acids are important for effective separation of biological active cis-diols. For the purpose of constructing a new type of saccharide-sensitive material which can not only provide convenient separation but also improve the access of boronic acid to guest molecules, the fluorogenic boronic acid terminated, thermo-sensitive polymers (BA-polyNIPAm) were grafted to an alkyne modified silica gel through the exploitation of click chemistry. The BA-polyNIPAm grafted silica gel (BA-polyNIPAm-SG) was characterized by FT-IR, fluorescence spectra, fluorescence microscopy, elemental analysis (EA), thermal gravimetric analysis (TGA), scanning electron microscope (SEM) and so on. BA-polyNIPAm-SG displayed affinity binding ability for saccharides under physiological pH value and allowed saccharides to be conveniently separated from solution. The maximum binding capacities for fructose and glucose are 83.2 μmol/g and 70.4 μmol/g polymer, respectively. The intensity of fluorescence emission of BA-polyNIPAm-SG increased with the increasing of fructose concentration. The present study provides a new kind of composite material which contains moveable and flexible grippers for recognizing and binding guest molecules. - Highlights: • Fluorogenic boronic acid terminated polymers were conjugated to silica particle. • The prepared material can conveniently separate saccharides from solution. • The prepared material displays increased fluorescence emission upon binding fructose.

Fluorescent boronic acid terminated polymer grafted silica particles synthesized via click chemistry for affinity separation of saccharides

International Nuclear Information System (INIS)

Xu, Zhifeng; Deng, Peihong; Tang, Siping; Li, Junhua

2014-01-01

Boronic acids are important for effective separation of biological active cis-diols. For the purpose of constructing a new type of saccharide-sensitive material which can not only provide convenient separation but also improve the access of boronic acid to guest molecules, the fluorogenic boronic acid terminated, thermo-sensitive polymers (BA-polyNIPAm) were grafted to an alkyne modified silica gel through the exploitation of click chemistry. The BA-polyNIPAm grafted silica gel (BA-polyNIPAm-SG) was characterized by FT-IR, fluorescence spectra, fluorescence microscopy, elemental analysis (EA), thermal gravimetric analysis (TGA), scanning electron microscope (SEM) and so on. BA-polyNIPAm-SG displayed affinity binding ability for saccharides under physiological pH value and allowed saccharides to be conveniently separated from solution. The maximum binding capacities for fructose and glucose are 83.2 μmol/g and 70.4 μmol/g polymer, respectively. The intensity of fluorescence emission of BA-polyNIPAm-SG increased with the increasing of fructose concentration. The present study provides a new kind of composite material which contains moveable and flexible grippers for recognizing and binding guest molecules. - Highlights: • Fluorogenic boronic acid terminated polymers were conjugated to silica particle. • The prepared material can conveniently separate saccharides from solution. • The prepared material displays increased fluorescence emission upon binding fructose

Oxygenated organic functional groups and their sources in single and submicron organic particles in MILAGRO 2006 campaign

Directory of Open Access Journals (Sweden)

S. Liu

2009-09-01

Full Text Available Fourier Transform Infrared (FTIR and X-ray Fluorescence (XRF were used to measure organic functional groups and elements of submicron particles collected during MILAGRO in March 2006 on three platforms: the Mexico City urban area (SIMAT, the high altitude site at 4010 m (Altzomoni, and the NCAR C130 aircraft. Scanning Transmission X-ray Microscopy (STXM and Near-Edge X-ray Absorption Fine Structure (NEXAFS were applied to single particle organic functional group abundance analysis of particles simultaneously collected at SIMAT and C130. Correlations of elemental concentrations showed different groups of source-related elements at SIMAT, Altzomoni, and C130, suggesting different processes affecting the air masses sampled at the three platforms. Cluster analysis resulted in seven distinct clusters of FTIR spectra, with the last three clusters consisting of spectra collected almost exclusively on the C130 platform, reflecting the variety of sources contributing to C130 samples. Positive Matrix Factorization (PMF of STXM-NEXAFS spectra identified three main factors representing soot, secondary, and biomass burning type spectra. PMF of FTIR spectra resulted in two fossil fuel combustion factors and one biomass burning factor, the former representative of source regions to the northeast and southwest of SIMAT. Alkane, carboxylic acid, amine, and alcohol functional groups were mainly associated with combustion related sources, while non-acid carbonyl groups were likely from biomass burning events. The majority of OM and O/C was attributed to combustion sources, although no distinction between direct emissions and atmospherically processed OM could be identified.

Mixing state of particles with secondary species by single particle aerosol mass spectrometer in an atmospheric pollution event

Science.gov (United States)

Xu, Lingling; Chen, Jinsheng

2016-04-01

Single particle aerosol mass spectrometer (SPAMS) was used to characterize size distribution, chemical composition, and mixing state of particles in an atmospheric pollution event during 20 Oct. - 5 Nov., 2015 in Xiamen, Southeast China. A total of 533,012 particle mass spectra were obtained and clustered into six groups, comprising of industry metal (4.5%), dust particles (2.6%), carbonaceous species (70.7%), K-Rich particles (20.7%), seasalt (0.6%) and other particles (0.9%). Carbonaceous species were further divided into EC (70.6%), OC (28.5%), and mixed ECOC (0.9%). There were 61.7%, 58.3%, 4.0%, and 14.6% of particles internally mixed with sulfate, nitrate, ammonium and C2H3O, respectively, indicating that these particles had undergone significant aging processing. Sulfate was preferentially mixed with carbonaceous particles, while nitrate tended to mix with metal-containing and dust particles. Compared to clear days, the fractions of EC-, metal- and dust particles remarkably increased, while the fraction of OC-containing particles decreased in pollution days. The mixing state of particles, excepted for OC-containing particles with secondary species was much stronger in pollution days than that in clear days, which revealed the significant influence of secondary particles in atmospheric pollution. The different activity of OC-containing particles might be related to their much smaller aerodynamic diameter. These results could improve our understanding of aerosol characteristics and could be helpful to further investigate the atmospheric process of particles.

Double-slit experiment with single wave-driven particles and its relation to quantum mechanics

DEFF Research Database (Denmark)

Andersen, Anders Peter; Madsen, Jacob; Reichelt, Christian Günther

2015-01-01

even though it is possible to determine unambiguously which slit the walking droplet passes. Here we argue, however, that the single-particle statistics in such an experiment will be fundamentally different from the single-particle statistics of quantum mechanics. Quantum mechanical interference takes...... place between different classical paths with precise amplitude and phase relations. In the double-slit experiment with walking droplets, these relations are lost since one of the paths is singled out by the droplet. To support our conclusions, we have carried out our own double-slit experiment, and our...... results, in particular the long and variable slit passage times of the droplets, cast strong doubt on the feasibility of the interference claimed by Couder and Fort. To understand theoretically the limitations of wave-driven particle systems as analogs to quantum mechanics, we introduce a Schro...

Interplay of single particle and collective response in molecular dynamics simulation of dusty plasma system

Science.gov (United States)

Maity, Srimanta; Das, Amita; Kumar, Sandeep; Tiwari, Sanat Kumar

2018-04-01

The collective response of the plasma medium is well known and has been explored extensively in the context of dusty plasma medium. On the other hand, the individual particle response associated with the collisional character giving rise to the dissipative phenomena has not been explored adequately. In this paper, two-dimensional molecular dynamics simulation of dust particles interacting via Yukawa potential has been considered. It has been shown that disturbances induced in a dust crystal elicit both collective and single particle responses. Generation of a few particles moving at speeds considerably higher than acoustic and/or shock speed (excited by the external disturbance) is observed. This is an indication of a single particle response. Furthermore, as these individual energetic particles propagate, the dust crystal is observed to crack along their path. Initially when the energy is high, these particles generate secondary energetic particles by the collisional scattering process. However, ultimately as these particles slow down they excite a collective response in the dust medium at secondary locations in a region which is undisturbed by the primary external disturbance. The condition when the cracking of the crystal stops and collective excitations get initiated has been identified quantitatively. The trailing collective primary disturbances would thus often encounter a disturbed medium with secondary and tertiary collective perturbations, thereby suffering significant modification in its propagation. It is thus clear that there is an interesting interplay (other than mere dissipation) between the single particle and collective response which governs the dynamics of any disturbance introduced in the medium.

Quantum chaos in nuclear single-particle motion and damping of giant resonances

International Nuclear Information System (INIS)

Pal, Santanu; Mukhopadhyay, Tapan

1995-01-01

The spectral statistics of single particle motion in deformed cavities with axial symmetry are presented. The single particle motion in the cavities considered are non-integrable and the systematics of the fluctuation measures of the spectra reveal a transition from regular to chaotic regime in the corresponding classical systems. Quantitative estimate of the degree of chaos enables us to introduce a correction factor to the one-body wall formula for the damping widths of isoscalar giant resonances. The damping widths calculated with this correction factor give much better agreement with experimental values than earlier calculations of one-body damping widths. (author). 21 refs., 5 figs

Digital quantification of rolling circle amplified single DNA molecules in a resistive pulse sensing nanopore.

Science.gov (United States)

Kühnemund, M; Nilsson, M

2015-05-15

Novel portable, sensitive and selective DNA sensor methods for bio-sensing applications are required that can rival conventionally used non-portable and expensive fluorescence-based sensors. In this paper, rolling circle amplification (RCA) products are detected in solution and on magnetic particles using a resistive pulse sensing (RPS) nanopore. Low amounts of DNA molecules are detected by padlock probes which are circularized in a strictly target dependent ligation reaction. The DNA-padlock probe-complex is captured on magnetic particles by sequence specific capture oligonucleotides and amplified by a short RCA. Subsequent RPS analysis is used to identify individual particles with single attached RCA products from blank particles. This proof of concept opens up for a novel non-fluorescent digital DNA quantification method that can have many applications in bio-sensing and diagnostic approaches. Copyright © 2014 Elsevier B.V. All rights reserved.

Development and characterization of a single particle laser ablation mass spectrometer (SPLAM for organic aerosol studies

Directory of Open Access Journals (Sweden)

F. Gaie-Levrel

2012-01-01

Full Text Available A single particle instrument was developed for real-time analysis of organic aerosol. This instrument, named Single Particle Laser Ablation Mass Spectrometry (SPLAM, samples particles using an aerodynamic lens system for which the theoretical performances were calculated. At the outlet of this system, particle detection and sizing are realized by using two continuous diode lasers operating at λ = 403 nm. Polystyrene Latex (PSL, sodium chloride (NaCl and dioctylphtalate (DOP particles were used to characterize and calibrate optical detection of SPLAM. The optical detection limit (DL and detection efficiency (DE were determined using size-selected DOP particles. The DE ranges from 0.1 to 90% for 100 and 350 nm DOP particles respectively and the SPLAM instrument is able to detect and size-resolve particles as small as 110–120 nm. During optical detection, particle scattered light from the two diode lasers, is detected by two photomultipliers and the detected signals are used to trigger UV excimer laser (λ = 248 nm used for one-step laser desorption ionization (LDI of individual aerosol particles. The formed ions are analyzed by a 1 m linear time-of-flight mass spectrometer in order to access to the chemical composition of individual particles. The TOF-MS detection limit for gaseous aromatic compounds was determined to be 0.85 × 10⁻¹⁵ kg (∼4 × 10³ molecules. DOP particles were also used to test the overall operation of the instrument. The analysis of a secondary organic aerosol, formed in a smog chamber by the ozonolysis of indene, is presented as a first application of the instrument. Single particle mass spectra were obtained with an effective hit rate of 8%. Some of these mass spectra were found to be very different from one particle to another possibly reflecting chemical differences within the investigated indene SOA particles. Our study shows that an exhaustive statistical analysis, over hundreds of particles

Fluorescence-based high-throughput functional profiling of ligand-gated ion channels at the level of single cells.

Directory of Open Access Journals (Sweden)

Sahil Talwar

Full Text Available Ion channels are involved in many physiological processes and are attractive targets for therapeutic intervention. Their functional properties vary according to their subunit composition, which in turn varies in a developmental and tissue-specific manner and as a consequence of pathophysiological events. Understanding this diversity requires functional analysis of ion channel properties in large numbers of individual cells. Functional characterisation of ligand-gated channels involves quantitating agonist and drug dose-response relationships using electrophysiological or fluorescence-based techniques. Electrophysiology is limited by low throughput and high-throughput fluorescence-based functional evaluation generally does not enable the characterization of the functional properties of each individual cell. Here we describe a fluorescence-based assay that characterizes functional channel properties at single cell resolution in high throughput mode. It is based on progressive receptor activation and iterative fluorescence imaging and delivers >100 dose-responses in a single well of a 384-well plate, using α1-3 homomeric and αβ heteromeric glycine receptor (GlyR chloride channels as a model system. We applied this assay with transiently transfected HEK293 cells co-expressing halide-sensitive yellow fluorescent protein and different GlyR subunit combinations. Glycine EC50 values of different GlyR isoforms were highly correlated with published electrophysiological data and confirm previously reported pharmacological profiles for the GlyR inhibitors, picrotoxin, strychnine and lindane. We show that inter and intra well variability is low and that clustering of functional phenotypes permits identification of drugs with subunit-specific pharmacological profiles. As this method dramatically improves the efficiency with which ion channel populations can be characterized in the context of cellular heterogeneity, it should facilitate systems

Turn-on fluorescence sensor based on single-walled-carbon-nanohorn-peptide complex for the detection of thrombin.

Science.gov (United States)

Zhu, Shuyun; Liu, Zhongyuan; Hu, Lianzhe; Yuan, Yali; Xu, Guobao

2012-12-14

Proteases play a central role in several widespread diseases. Thus, there is a great need for the fast and sensitive detection of various proteolytic enzymes. Herein, we have developed a carbon nanotube (CNT)-based protease biosensing platform that uses peptides as a fluorescence probe for the first time. Single-walled carbon nanohorns (SWCNHs) and thrombin were used to demonstrate this detection strategy. SWCNHs can adsorb a fluorescein-based dye (FAM)-labeled peptide (FAM-pep) and quench the fluorescence of FAM. In contrast, thrombin can cleave FAM-pep on SWCNHs and recover the fluorescence of FAM, which allows the sensitive detection of thrombin. This biosensor has a high sensitivity and selectivity toward thrombin, with a detection limit of 100 pM. Copyright © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Authenticated multi-user quantum key distribution with single particles

Science.gov (United States)

Lin, Song; Wang, Hui; Guo, Gong-De; Ye, Guo-Hua; Du, Hong-Zhen; Liu, Xiao-Fen

2016-03-01

Quantum key distribution (QKD) has been growing rapidly in recent years and becomes one of the hottest issues in quantum information science. During the implementation of QKD on a network, identity authentication has been one main problem. In this paper, an efficient authenticated multi-user quantum key distribution (MQKD) protocol with single particles is proposed. In this protocol, any two users on a quantum network can perform mutual authentication and share a secure session key with the assistance of a semi-honest center. Meanwhile, the particles, which are used as quantum information carriers, are not required to be stored, therefore the proposed protocol is feasible with current technology. Finally, security analysis shows that this protocol is secure in theory.

Summary report of the group on single-particle nonlinear dynamics

International Nuclear Information System (INIS)

Axinescu, S.; Bartolini, R.; Bazzani, A.

1996-10-01

This report summarizes the research on single-particle nonlinear beam dynamics. It discusses the following topics: analytical and semi-analytical tools; early prediction of the dynamic aperture; how the results are commonly presented; Is the mechanism of the dynamic aperture understand; ripple effects; and beam-beam effects

Fluorescent nuclear track images of Ag-activated phosphate glass irradiated with photons and heavy charged particles

Energy Technology Data Exchange (ETDEWEB)

Kurobori, Toshio, E-mail: kurobori@staff.kanazawa-u.ac.jp [Graduate School of Natural Science and Technology, Kanazawa University, Kakuma, Kanazawa 920-1192 (Japan); Yanagida, Yuka [Oarai Research Center, Chiyoda Technol Corporation, Oarai-machi, Ibaraki 311-1313 (Japan); Kodaira, Satoshi [National Institute of Radiological Sciences, 4-9-1 Anagawa, Inage-ku, Chiba 263-8555 (Japan); Shirao, Taichi [Nikon Instech Co., Ltd., Tanakanishi, Sakyo-ku, Kyoto 606-8221 (Japan)

2017-05-21

In this paper we report about the demonstration of the nuclear track imaging capabilities of Ag-activated phosphate glass. A 375 nm laser and confocal laser scanning microscopy (CLSM) were respectively used for track excitation and detection. Specifically, the blue and orange radiophotoluminescent (RPL) tracks and dose distributions observed after irradiation with soft X-rays, gamma rays and heavy charged particles (HCPs) are examined. In addition, the origins of the reductions in RPL efficiency for high-dose X-ray irradiation and for irradiation with HCPs with high linear energy transfer (LET) values are investigated via a CLSM and a conventional fluorescent reader and discussed. - Highlights: • 3D track images are demonstrated using a confocal laser microscopy. • Fluorescent track detectors are based on RPL Ag-doped phosphate glass. • The dose distributions are examined for X-ray, gamma ray and HCP irradiations. • The origins of the reduction in RPL efficiency are investigated and discussed.

Fluorescent nuclear track images of Ag-activated phosphate glass irradiated with photons and heavy charged particles

International Nuclear Information System (INIS)

Kurobori, Toshio; Yanagida, Yuka; Kodaira, Satoshi; Shirao, Taichi

2017-01-01

In this paper we report about the demonstration of the nuclear track imaging capabilities of Ag-activated phosphate glass. A 375 nm laser and confocal laser scanning microscopy (CLSM) were respectively used for track excitation and detection. Specifically, the blue and orange radiophotoluminescent (RPL) tracks and dose distributions observed after irradiation with soft X-rays, gamma rays and heavy charged particles (HCPs) are examined. In addition, the origins of the reductions in RPL efficiency for high-dose X-ray irradiation and for irradiation with HCPs with high linear energy transfer (LET) values are investigated via a CLSM and a conventional fluorescent reader and discussed. - Highlights: • 3D track images are demonstrated using a confocal laser microscopy. • Fluorescent track detectors are based on RPL Ag-doped phosphate glass. • The dose distributions are examined for X-ray, gamma ray and HCP irradiations. • The origins of the reduction in RPL efficiency are investigated and discussed.

Single particle level density in a finite depth potential well

International Nuclear Information System (INIS)

Shlomo, S.; Kolomietz, V.M.; Dejbakhsh, H.

1997-01-01

We consider the single particle level density g(ε) of a realistic finite depth potential well, concentrating on the continuum (ε>0) region. We carry out quantum-mechanical calculations of the partial level density g l (ε), associated with a well-defined orbital angular momentum l≤40, using the phase-shift derivative method and the Greens-function method and compare the results with those obtained using the Thomas-Fermi approximation. We also numerically calculate g(ε) as a l sum of g l (ε) up to a certain value of scr(l) max ≤40 and determine the corresponding smooth level densities using the Strutinsky smoothing procedure. We demonstrate, in accordance with Levinson close-quote s theorem, that the partial contribution g l (ε) to the single particle level density from continuum states has positive and negative values. However, g(ε) is nonnegative. We also point out that this is not the case for an energy-dependent potential well. copyright 1997 The American Physical Society

Charged-particle spectroscopy in organic semiconducting single crystals

Energy Technology Data Exchange (ETDEWEB)

Ciavatti, A.; Basiricò, L.; Fraboni, B. [Department of Physics and Astronomy, University of Bologna, Viale Berti Pichat 6/2, 40127 Bologna (Italy); Sellin, P. J. [Department of Physics, University of Surrey, Guildford, Surrey GU2 7XH (United Kingdom); Fraleoni-Morgera, A. [ELETTRA-Sincrotrone Trieste, Strada Statale 14, Km 163.5, Basovizza, Trieste (Italy); Department of Engineering and Architecture, University of Trieste, V. Valerio 10, 34100 Trieste (Italy); CNR-Nano S3 Institute, Via Campi 213/A, 41125 Modena (Italy)

2016-04-11

The use of organic materials as radiation detectors has grown, due to the easy processability in liquid phase at room temperature and the possibility to cover large areas by means of low cost deposition techniques. Direct charged-particle detectors based on solution-grown Organic Semiconducting Single Crystals (OSSCs) are shown to be capable to detect charged particles in pulse mode, with very good peak discrimination. The direct charged-particle detection in OSSCs has been assessed both in the planar and in the vertical axes, and a digital pulse processing algorithm has been used to perform pulse height spectroscopy and to study the charge collection efficiency as a function of the applied bias voltage. Taking advantage of the charge spectroscopy and the good peak discrimination of pulse height spectra, an Hecht-like behavior of OSSCs radiation detectors is demonstrated. It has been possible to estimate the mobility-lifetime value in organic materials, a fundamental parameter for the characterization of radiation detectors, whose results are equal to μτ{sub coplanar} = (5 .5 ± 0.6 ) × 10{sup −6} cm{sup 2}/V and μτ{sub sandwich} = (1 .9 ± 0.2 ) × 10{sup −6} cm{sup 2}/V, values comparable to those of polycrystalline inorganic detectors. Moreover, alpha particles Time-of-Flight experiments have been carried out to estimate the drift mobility value. The results reported here indicate how charged-particle detectors based on OSSCs possess a great potential as low-cost, large area, solid-state direct detectors operating at room temperature. More interestingly, the good detection efficiency and peak discrimination observed for charged-particle detection in organic materials (hydrogen-rich molecules) are encouraging for their further exploitation in the detection of thermal and high-energy neutrons.

Quantification of phosphorus in single cells using synchrotron X-ray fluorescence

Energy Technology Data Exchange (ETDEWEB)

Núñez-Milland, Daliángelis R. [Department of Chemistry and Biochemistry, University of South Carolina, Columbia, SC 29208 (United States); Baines, Stephen B. [Department of Ecology and Evolution, Stony Brook University, Stony Brook, NY 11755 (United States); Vogt, Stefan [Experimental Facilities Division, Advanced Photon Source, Argonne National Laboratory, Argonne, IL (United States); Twining, Benjamin S., E-mail: btwining@bigelow.org [Department of Chemistry and Biochemistry, University of South Carolina, Columbia, SC 29208 (United States)

2010-07-01

Phosphorus abundance was quantified in individual phytoplankton cells by synchrotron X-ray fluorescence and compared with bulk spectrophotometric measurements to confirm accuracy of quantification. Figures of merit for P quantification on three different types of transmission electron microscopy grids are compared to assess possible interferences. Phosphorus is required for numerous cellular compounds and as a result can serve as a useful proxy for total cell biomass in studies of cell elemental composition. Single-cell analysis by synchrotron X-ray fluorescence (SXRF) enables quantitative and qualitative analyses of cell elemental composition with high elemental sensitivity. Element standards are required to convert measured X-ray fluorescence intensities into element concentrations, but few appropriate standards are available, particularly for the biologically important element P. Empirical P conversion factors derived from other elements contained in certified thin-film standards were used to quantify P in the model diatom Thalassiosira pseudonana, and the measured cell quotas were compared with those measured in bulk by spectrophotometry. The mean cellular P quotas quantified with SXRF for cells on Au, Ni and nylon grids using this approach were not significantly different from each other or from those measured spectrophotometrically. Inter-cell variability typical of cell populations was observed. Additionally, the grid substrates were compared for their suitability to P quantification based on the potential for spectral interferences with P. Nylon grids were found to have the lowest background concentrations and limits of detection for P, while background concentrations in Ni and Au grids were 1.8- and 6.3-fold higher. The advantages and disadvantages of each grid type for elemental analysis of individual phytoplankton cells are discussed.

Dual responsive dysprosium-doped hydroxyapatite particles and toxicity reduction after functionalization with folic and glucuronic acids

Energy Technology Data Exchange (ETDEWEB)

Sánchez Lafarga, Ana Karen; Pacheco Moisés, Fermín P. [Departamento de Química, Universidad de Guadalajara, Marcelino García Barragán 1421, C.P. 44430, Guadalajara, Jalisco (Mexico); Gurinov, Andrey [Research Resources Center for Magnetic Resonance, Saint Petersburg State University, Universitetskij pr. 26, 198504 St. Petersburg (Russian Federation); Ortiz, Genaro Gabriel [Laboratorio Desarrollo-Envejecimiento, Enfermedades Neurodegenerativas, Centro de Investigación Biomédica de Occidente (CIBO), Instituto Mexicano de Seguro Social (IMSS), Guadalajara, Jalisco (Mexico); Carbajal Arízaga, Gregorio Guadalupe, E-mail: gregoriocarbajal@yahoo.com.mx [Departamento de Química, Universidad de Guadalajara, Marcelino García Barragán 1421, C.P. 44430, Guadalajara, Jalisco (Mexico)

2015-03-01

The development of probes for biomedical applications demands materials with low toxicity levels besides fluorescence or magnetic properties to be detected by confocal microscopes or MRI resonators. Several drug delivery systems or other biomedical materials prepared with hydroxyapatite have been proposed, however, toxicity effects might arise when the size of particles is nanometric. In this study, hydroxyapatite functionalized with glucuronic or folic acids presented lower oxidative stress, measured from lipoperoxides and nitric oxide indicators in rats than pure hydroxyapatite. In separated experiments, hydroxyapatite was doped with dysprosium cations by coprecipitation producing a single crystal phase with fluorescent properties easily visualized by confocal microscopy when excited at 488 nm. These particles also presented the ability to modify the proton relaxation time in T1 maps collected by magnetic resonance imaging. These modified hydroxyapatite nanoparticles could be candidates to design bimodal probes with low toxicity. - Highlights: • Hydroxyapatite functionalized with glucuronic acid reduced oxidative stress in rats. • Functionalization with folic acid reduced oxidative stress in rats. • Dysprosium doping does not affect the crystalline structure of hydroxyapatite. • Dysprosium doped particles are visible in fluorescent microscope. • Dysprosium doped particles act as MRI contrast agents.

Dual responsive dysprosium-doped hydroxyapatite particles and toxicity reduction after functionalization with folic and glucuronic acids

International Nuclear Information System (INIS)

Sánchez Lafarga, Ana Karen; Pacheco Moisés, Fermín P.; Gurinov, Andrey; Ortiz, Genaro Gabriel; Carbajal Arízaga, Gregorio Guadalupe

2015-01-01

The development of probes for biomedical applications demands materials with low toxicity levels besides fluorescence or magnetic properties to be detected by confocal microscopes or MRI resonators. Several drug delivery systems or other biomedical materials prepared with hydroxyapatite have been proposed, however, toxicity effects might arise when the size of particles is nanometric. In this study, hydroxyapatite functionalized with glucuronic or folic acids presented lower oxidative stress, measured from lipoperoxides and nitric oxide indicators in rats than pure hydroxyapatite. In separated experiments, hydroxyapatite was doped with dysprosium cations by coprecipitation producing a single crystal phase with fluorescent properties easily visualized by confocal microscopy when excited at 488 nm. These particles also presented the ability to modify the proton relaxation time in T1 maps collected by magnetic resonance imaging. These modified hydroxyapatite nanoparticles could be candidates to design bimodal probes with low toxicity. - Highlights: • Hydroxyapatite functionalized with glucuronic acid reduced oxidative stress in rats. • Functionalization with folic acid reduced oxidative stress in rats. • Dysprosium doping does not affect the crystalline structure of hydroxyapatite. • Dysprosium doped particles are visible in fluorescent microscope. • Dysprosium doped particles act as MRI contrast agents

The Mapping X-ray Fluorescence Spectrometer (MapX)

Science.gov (United States)

Sarrazin, P.; Blake, D. F.; Marchis, F.; Bristow, T.; Thompson, K.

2017-12-01

Many planetary surface processes leave traces of their actions as features in the size range 10s to 100s of microns. The Mapping X-ray Fluorescence Spectrometer (MapX) will provide elemental imaging at 100 micron spatial resolution, yielding elemental chemistry at a scale where many relict physical, chemical, or biological features can be imaged and interpreted in ancient rocks on planetary bodies and planetesimals. MapX is an arm-based instrument positioned on a rock or regolith with touch sensors. During an analysis, an X-ray source (tube or radioisotope) bombards the sample with X-rays or alpha-particles / gamma-rays, resulting in sample X-ray Fluorescence (XRF). X-rays emitted in the direction of an X-ray sensitive CCD imager pass through a 1:1 focusing lens (X-ray micro-pore Optic (MPO)) that projects a spatially resolved image of the X-rays onto the CCD. The CCD is operated in single photon counting mode so that the energies and positions of individual X-ray photons are recorded. In a single analysis, several thousand frames are both stored and processed in real-time. Higher level data products include single-element maps with a lateral spatial resolution of 100 microns and quantitative XRF spectra from ground- or instrument- selected Regions of Interest (ROI). XRF spectra from ROI are compared with known rock and mineral compositions to extrapolate the data to rock types and putative mineralogies. When applied to airless bodies and implemented with an appropriate radioisotope source for alpha-particle excitation, MapX will be able to analyze biogenic elements C, N, O, P, S, in addition to the cations of the rock-forming elements >Na, accessible with either X-ray or gamma-ray excitation. The MapX concept has been demonstrated with a series of lab-based prototypes and is currently under refinement and TRL maturation.

Aperture and counting rate of rectangular telescopes for single and multiple parallel particles. [Spark chamber telescopes

Energy Technology Data Exchange (ETDEWEB)

D' Ettorre Piazzoli, B; Mannocchi, G [Consiglio Nazionale delle Ricerche, Turin (Italy). Lab. di Cosmo-Geofisica; Melone, S [Istituto di Fisica dell' Universita, Ancona, Italy; Picchi, P; Visentin, R [Comitato Nazionale per l' Energia Nucleare, Frascati (Italy). Laboratori Nazionali di Frascati

1976-06-01

Expressions for the counting rate of rectangular telescopes in the case of single as well as multiple particles are given. The aperture for single particles is obtained in the form of a double integral and analytical solutions are given for some cases. The intensity for different multiplicities of parallel particles is related to the geometry of the detectors and to the features of the radiation. This allows an absolute comparison between the data recorded by different devices.

Generating high-quality single droplets for optical particle characterization with an easy setup

Science.gov (United States)

Xu, Jie; Ge, Baozhen; Meng, Rui

2018-06-01

The high-performance and micro-sized single droplet is significant for optical particle characterization. We develop a single-droplet generator (SDG) based on a piezoelectric inkjet technique with advantages of low cost and easy setup. By optimizing the pulse parameters, we achieve various size single droplets. Further investigations reveal that SDG generates single droplets of high quality, demonstrating good sphericity, monodispersity and a stable length of several millimeters.

Deflection of high energy channeled charged particles by elastically bent silicon single crystals

International Nuclear Information System (INIS)

Gibson, W.M.; Kim, I.J.; Pisharodoy, M.; Salman, S.M.; Sun, C.R.; Wang, G.H.; Wijayawardana, R.; Forster, J.S.; Mitchell, I.V.; Baker, S.I.; Carrigan, R.A. Jr.; Toohig, T.E.; Avdeichikov, V.V.; Ellison, J.A.; Siffert, P.

1984-01-01

An experiment has been carried out to observe the deflection of charged particles by planar channeling in bent single crystals of silicon for protons with energy up to 180 GeV. Anomolous loss of particles from the center point of a three point bending apparatus was observed at high incident particle energy. This effect has been exploited to fashion a 'dechanneling spectrometer' to study dechanneling effects due to centripital displacement of channeled particle trajectories in a bent crystal. The bending losses generally conform to the predictions of calculations based on a classical model. (orig.)

Statistical and direct decay of high-lying single-particle excitations

International Nuclear Information System (INIS)

Gales, S.

1993-01-01

Transfer reactions induced by hadronic probes at intermediate energies have revealed a rich spectrum of high-lying excitations embedded in the nuclear continuum. The investigation of their decay properties is believed to be a severe test of their microscopic structure as predicted by microscopic nuclear models. In addition the degree of damping of these simple modes in the nuclear continuum can be obtained by means of the measured particle (n,p) decay branching ratios. The neutron and proton decay studies of high-lying single-particle states in heavy nuclei are presented. (author). 13 refs., 9 figs

Evolution of Single-Particle Energies for N=9 Nuclei at Large N/Z

Directory of Open Access Journals (Sweden)

Wuosmaa A. H.

2014-03-01

Full Text Available We have studied the nucleus 14B using the 13B(d,p14B and 15C(d,3He14B reactions. The two reactions provide complementary information about the negative-parity 1s1/2 and 0d5/2 neutron single-particle states in 14B. The data from the (d,p reaction give neutron-spectroscopic strengths for these levels, and the (d,3He results confirm the existence of a broad 2- excited state suggested in the literature. Together these results provide estimates of the sd-shell neutron effective single-particle energies in 14B.

Plasmon excitation in single wall carbon nanotubes by penetrating charged particles

International Nuclear Information System (INIS)

Segui, Silvina; Gervasoni, Juana L; Arista, Néstor R; Mowbray, Duncan J; Mišković, Zoran L

2012-01-01

In this work we study the excitation of plasmons due to the incidence of a charged particle passing through a single wall carbon nanotube. We use a quantized hydrodynamic, in which the σ and π electrons characteristic of these carbonaceous structures are depicted as two interacting 2-dimensional fluids, to calculate the average number of plasmons excited. We analyze the contribution of the different plasmon modes in a variety of configurations, and study the energy lost by the incident particle.