The effects of surface-charged submicron polystyrene particles on the structure and performance of PSF forward osmosis membrane

Science.gov (United States)

Zuo, Hao-Ran; Fu, Jia-Bei; Cao, Gui-Ping; Hu, Nian; Lu, Hui; Liu, Hui-Qing; Chen, Peng-Peng; Yu, Jie

2018-04-01

Monodisperse surface-charged submicron polystyrene particles were designed, synthesized, and blended into polysulfone (PSF) support layer to prepare forward osmosis (FO) membrane with high performance. The membrane incorporated with particles were characterized with respect to morphology, porosity, and internal osmotic pressure (IOP). Results showed that the polymer particles not only increased the hydrophilicity and porosity of support layer, but also generated considerable IOP, which helped markedly decreasing the structure parameter from 1550 to 670 μm. The measured mass transfer parameters further confirmed the beneficial effects of the surface-charged submicron polymer particles on the performance of FO membrane. For instance, the water permeability coefficient (5.37 L m-2 h-1 bar-1) and water flux (49.7 L m-2 h-1) of the FO membrane incorporated with 5 wt% particles were almost twice as much as that of FO membrane without incorporation. This study suggests that monodisperse surface-charged submicron polymer particles are potential modifiers for improving the performance of FO membranes.

[Investigation of the distribution of water clusters in vegetables, fruits, and natural waters by flicker noise spectroscopy].

Science.gov (United States)

Zubov, A V; Zubov, K V; Zubov, V A

2007-01-01

The distribution of water clusters in fresh rain water and in rain water that was aged for 30 days (North Germany, 53 degrees 33' N, 12 degrees 47' E, 293 K, rain on 25.06.06) as well as in fresh vegetables and fruits was studied by flicker noise spectroscopy. In addition, the development of water clusters in apples and potatoes during ripening in 2006 was investigated. A different distribution of water clusters in irrigation water (river and rain) and in the biomatrix of vegetables (potatoes, onions, tomatoes, red beets) and fruits (apples, bananas) was observed. It was concluded that the cluster structure of irrigation water differs from that of water of the biomatrix of vegetables and fruits and depends on drought and the biomatrix nature. Water clusters in plants are more stable and reproducible than water clusters in natural water. The main characteristics of cluster formation in materials studied were given. The oscillation frequencies of water clusters in plants (biofield) are given at which they interact with water clusters of the Earth hydrosphere. A model of series of clusters 16(H2O)100 4(H2O)402 2(H2O)903 (H2O)1889 in the biomatrix of vegetables and fruits was discussed.

Water Cluster Leaders Meeting Summary Report 2016

Science.gov (United States)

As part of its efforts to support environmental technology innovation clusters, U.S. EPA hosted a Water Technology Innovation Cluster Leaders Meeting on September 25, 2016, in New Orleans, Louisiana. The meeting was an opportunity for cluster leaders from across the globe to meet...

Explosions of water clusters in intense laser fields

International Nuclear Information System (INIS)

Kumarappan, V.; Krishnamurthy, M.; Mathur, D.

2003-01-01

Energetic, highly charged oxygen ions O q+ (q≤6), are copiously produced upon laser field-induced disassembly of highly charged water clusters, (H 2 O) n and (D 2 O) n , n∼60, that are formed by seeding high-pressure helium or argon with water vapor. Ar n clusters (n∼40 000) formed under similar experimental conditions are found to undergo disassembly in the Coulomb explosion regime, with the energies of Ar q+ ions showing a q 2 dependence. Water clusters, which are argued to be considerably smaller in size, should also disassemble in the same regime, but the energies of fragment O q+ ions are found to depend linearly on q which, according to prevailing wisdom, ought to be a signature of hydrodynamic expansion that is expected of much larger clusters. The implication of these observations on our understanding of the two cluster explosion regimes, Coulomb explosion and hydrodynamic expansion, is discussed. Our results indicate that charge state dependences of ion energy do not constitute an unambiguous experimental signature of cluster explosion regime

Water quality assessment with hierarchical cluster analysis based on Mahalanobis distance.

Science.gov (United States)

Du, Xiangjun; Shao, Fengjing; Wu, Shunyao; Zhang, Hanlin; Xu, Si

2017-07-01

Water quality assessment is crucial for assessment of marine eutrophication, prediction of harmful algal blooms, and environment protection. Previous studies have developed many numeric modeling methods and data driven approaches for water quality assessment. The cluster analysis, an approach widely used for grouping data, has also been employed. However, there are complex correlations between water quality variables, which play important roles in water quality assessment but have always been overlooked. In this paper, we analyze correlations between water quality variables and propose an alternative method for water quality assessment with hierarchical cluster analysis based on Mahalanobis distance. Further, we cluster water quality data collected form coastal water of Bohai Sea and North Yellow Sea of China, and apply clustering results to evaluate its water quality. To evaluate the validity, we also cluster the water quality data with cluster analysis based on Euclidean distance, which are widely adopted by previous studies. The results show that our method is more suitable for water quality assessment with many correlated water quality variables. To our knowledge, it is the first attempt to apply Mahalanobis distance for coastal water quality assessment.

Hydration of a Large Anionic Charge Distribution - Naphthalene-Water Cluster Anions

Science.gov (United States)

Weber, J. Mathias; Adams, Christopher L.

2010-06-01

We report the infrared spectra of anionic clusters of naphthalene with up to three water molecules. Comparison of the experimental infrared spectra with theoretically predicted spectra from quantum chemistry calculations allow conclusions regarding the structures of the clusters under study. The first water molecule forms two hydrogen bonds with the π electron system of the naphthalene moiety. Subsequent water ligands interact with both the naphthalene and the other water ligands to form hydrogen bonded networks, similar to other hydrated anion clusters. Naphthalene-water anion clusters illustrate how water interacts with negative charge delocalized over a large π electron system. The clusters are interesting model systems that are discussed in the context of wetting of graphene surfaces and polyaromatic hydrocarbons.

Hydration dynamics in water clusters via quantum molecular dynamics simulations

Energy Technology Data Exchange (ETDEWEB)

Turi, László, E-mail: turi@chem.elte.hu [Department of Physical Chemistry, Eötvös Loránd University, Budapest 112, P. O. Box 32, H-1518 (Hungary)

2014-05-28

We have investigated the hydration dynamics in size selected water clusters with n = 66, 104, 200, 500, and 1000 water molecules using molecular dynamics simulations. To study the most fundamental aspects of relaxation phenomena in clusters, we choose one of the simplest, still realistic, quantum mechanically treated test solute, an excess electron. The project focuses on the time evolution of the clusters following two processes, electron attachment to neutral equilibrated water clusters and electron detachment from an equilibrated water cluster anion. The relaxation dynamics is significantly different in the two processes, most notably restoring the equilibrium final state is less effective after electron attachment. Nevertheless, in both scenarios only minor cluster size dependence is observed. Significantly different relaxation patterns characterize electron detachment for interior and surface state clusters, interior state clusters relaxing significantly faster. This observation may indicate a potential way to distinguish surface state and interior state water cluster anion isomers experimentally. A comparison of equilibrium and non-equilibrium trajectories suggests that linear response theory breaks down for electron attachment at 200 K, but the results converge to reasonable agreement at higher temperatures. Relaxation following electron detachment clearly belongs to the linear regime. Cluster relaxation was also investigated using two different computational models, one preferring cavity type interior states for the excess electron in bulk water, while the other simulating non-cavity structure. While the cavity model predicts appearance of several different hydrated electron isomers in agreement with experiment, the non-cavity model locates only cluster anions with interior excess electron distribution. The present simulations show that surface isomers computed with the cavity predicting potential show similar dynamical behavior to the interior clusters of

Development and scintigraphic evaluation of submicron sized dry powder inhalation formulation of fluticasone propionate in healthy human volunteers

International Nuclear Information System (INIS)

Ali, Sultana S.; Ahmad, F.J.; Khar, R.K.; Rathore, V.P.; Ali, Rashid; Rawat, H.S.; Chopra, M.K.; Mittal, G.; Bhatnagar, A.

2010-01-01

Full text: Objective of the present study concerns formulation and evaluation of submicron sized dry powder inhalation formulation of Fluticasone propionate for the treatment of bronchial asthma, COPD and a new life saving treatment option in restrictive lung diseases such as Interstitial Lung Disease (ILD), toxic and non-cardiogenic pulmonary inflammations or pulmonary edema, which have no effective treatment presently. Materials and Methods: The submicron sized particles were prepared by precipitation method using acetone as solvent and water as antisolvent. Poloxamer F127 was used as stabilizer. Both submicronized and micronized particles were characterized using FTIR, XRD, DSC, SEM and TEM. The mass median aerodynamic diameter (MMAD) of the submicronized and micronized API was calculated using Andersen cascade impactor. The prepared particles and micronized Active Pharmaceutical Ingredient (API) were radiolabeled with 99m Tc. Size3 HPMC capsules were filled with the 12.5 mg radiolabeled blend (100μg Fluticasone propionate and 12.4mg inhalable lactose) and given to healthy volunteers to assess the comparative pulmonary deposition. Results: The prepared formulation has shown better lung deposition as compared to micronized API. The MMAD of submicronized particles was in the range of 1 - 5 μm while the MMAD of micronized API was in the range of 5 - 15μm. Conclusion: The developed submicron sized dry powder inhalation formulation has better lung deposition as compared to micron sized API and it will become a better treatment option for the bronchial asthma, COPD and ILDs

Hierarchical clusters of phytoplankton variables in dammed water bodies

Science.gov (United States)

Silva, Eliana Costa e.; Lopes, Isabel Cristina; Correia, Aldina; Gonçalves, A. Manuela

2017-06-01

In this paper a dataset containing biological variables of the water column of several Portuguese reservoirs is analyzed. Hierarchical cluster analysis is used to obtain clusters of phytoplankton variables of the phylum Cyanophyta, with the objective of validating the classification of Portuguese reservoirs previewly presented in [1] which were divided into three clusters: (1) Interior Tagus and Aguieira; (2) Douro; and (3) Other rivers. Now three new clusters of Cyanophyta variables were found. Kruskal-Wallis and Mann-Whitney tests are used to compare the now obtained Cyanophyta clusters and the previous Reservoirs clusters, in order to validate the classification of the water quality of reservoirs. The amount of Cyanophyta algae present in the reservoirs from the three clusters is significantly different, which validates the previous classification.

Assessment of surface water quality using hierarchical cluster analysis

Directory of Open Access Journals (Sweden)

Dheeraj Kumar Dabgerwal

2016-02-01

Full Text Available This study was carried out to assess the physicochemical quality river Varuna inVaranasi,India. Water samples were collected from 10 sites during January-June 2015. Pearson correlation analysis was used to assess the direction and strength of relationship between physicochemical parameters. Hierarchical Cluster analysis was also performed to determine the sources of pollution in the river Varuna. The result showed quite high value of DO, Nitrate, BOD, COD and Total Alkalinity, above the BIS permissible limit. The results of correlation analysis identified key water parameters as pH, electrical conductivity, total alkalinity and nitrate, which influence the concentration of other water parameters. Cluster analysis identified three major clusters of sampling sites out of total 10 sites, according to the similarity in water quality. This study illustrated the usefulness of correlation and cluster analysis for getting better information about the river water quality.International Journal of Environment Vol. 5 (1 2016,  pp: 32-44

Topological clustering as a tool for planning water quality monitoring in water distribution networks

DEFF Research Database (Denmark)

Kirstein, Jonas Kjeld; Albrechtsen, Hans-Jørgen; Rygaard, Martin

2015-01-01

) identify steady clusters for a part of the network where an actual contamination has occurred; (2) analyze this event by the use of mesh diagrams; and (3) analyze the use of mesh diagrams as a decision support tool for planning water quality monitoring. Initially, the network model was divided...... into strongly and weakly connected clusters for selected time periods and mesh diagrams were used for analysing cluster connections in the Nørrebro district. Here, areas of particular interest for water quality monitoring were identified by including user-information about consumption rates and consumers...... particular sensitive towards water quality deterioration. The analysis revealed sampling locations within steady clusters, which increased samples' comparability over time. Furthermore, the method provided a simplified overview of water movement in complex distribution networks, and could assist...

The role of adsorbed water on the friction of a layer of submicron particles

Science.gov (United States)

Sammis, Charles G.; Lockner, David A.; Reches, Ze’ev

2011-01-01

Anomalously low values of friction observed in layers of submicron particles deformed in simple shear at high slip velocities are explained as the consequence of a one nanometer thick layer of water adsorbed on the particles. The observed transition from normal friction with an apparent coefficient near μ = 0.6 at low slip speeds to a coefficient near μ = 0.3 at higher slip speeds is attributed to competition between the time required to extrude the water layer from between neighboring particles in a force chain and the average lifetime of the chain. At low slip speeds the time required for extrusion is less than the average lifetime of a chain so the particles make contact and lock. As slip speed increases, the average lifetime of a chain decreases until it is less than the extrusion time and the particles in a force chain never come into direct contact. If the adsorbed water layer enables the otherwise rough particles to rotate, the coefficient of friction will drop to μ = 0.3, appropriate for rotating spheres. At the highest slip speeds particle temperatures rise above 100°C, the water layer vaporizes, the particles contact and lock, and the coefficient of friction rises to μ = 0.6. The observed onset of weakening at slip speeds near 0.001 m/s is consistent with the measured viscosity of a 1 nm thick layer of adsorbed water, with a minimum particle radius of approximately 20 nm, and with reasonable assumptions about the distribution of force chains guided by experimental observation. The reduction of friction and the range of velocities over which it occurs decrease with increasing normal stress, as predicted by the model. Moreover, the analysis predicts that this high-speed weakening mechanism should operate only for particles with radii smaller than approximately 1 μm. For larger particles the slip speed required for weakening is so large that frictional heating will evaporate the adsorbed water and weakening will not occur.

Investigation of the Structures and Energy Landscapes of Thiocyanate-Water Clusters

Directory of Open Access Journals (Sweden)

Lewis C. Smeeton

2017-03-01

Full Text Available The Basin Hopping search method is used to find the global minima (GM and map the energy landscapes of thiocyanate-water clusters, (SCN−(H2On with 3–50 water molecules, with empirical potentials describing the ion-water and water-water interactions. (It should be noted that beyond n = 23, the lowest energy structures were only found in 1 out of 8 searches so they are unlikely to be the true GM but are indicative low energy structures. As for pure water clusters, the low energy isomers of thiocyanate-water clusters show a preponderance of fused water cubes and pentagonal prisms, with the weakly solvated thiocyanate ion lying on the surface, replacing two water molecules along an edge of a water polyhedron and with the sulfur atom in lower coordinated sites than nitrogen. However, by comparison with Density Functional Theory (DFT calculations, the empirical potential is found to overestimate the strength of the thiocyanate-water interaction, especially O–H⋯S, with low energy DFT structures having lower coordinate N and (especially S atoms than for the empirical potential. In the case of these finite ion-water clusters, the chaotropic (“disorder-making” thiocyanate ion weakens the water cluster structure but the water molecule arrangement is not significantly changed.

Micromagnetic simulations of submicron cobalt dots

International Nuclear Information System (INIS)

Parker, G. J.; Cerjan, C.

2000-01-01

Numerical simulations of submicron Co extruded elliptical dots were performed to illustrate the relative importance of different physical parameters on the switching behavior in the easy direction. Shape, size, magnetic moment magnitude, and the magnitude and distribution of the crystalline anisotropicity were varied. The simulation represents magnetostatic, exchange, and crystalline anisotropicity fields on a structured mesh using finite difference techniques. The smooth boundary of the dots is accurately represented by use of the embedded curve boundary method. Agreement with experimental hysteresis measurements of submicron dot arrays is obtained when an appropriate angular distribution of the grain anisotropicity axes is invoked. (c) 2000 American Institute of Physics

Experimental equivalent cluster-size distributions in nano-metric volumes of liquid water

International Nuclear Information System (INIS)

Grosswendt, B.; De Nardo, L.; Colautti, P.; Pszona, S.; Conte, V.; Tornielli, G.

2004-01-01

Ionisation cluster-size distributions in nano-metric volumes of liquid water were determined for alpha particles at 4.6 and 5.4 MeV by measuring cluster-size frequencies in small gaseous volumes of nitrogen or propane at low gas pressure as well as by applying a suitable scaling procedure. This scaling procedure was based on the mean free ionisation lengths of alpha particles in water and in the gases measured. For validation, the measurements of cluster sizes in gaseous volumes and the cluster-size formation in volumes of liquid water of equivalent size were simulated by Monte Carlo methods. The experimental water-equivalent cluster-size distributions in nitrogen and propane are compared with those in liquid water and show that cluster-size formation by alpha particles in nitrogen or propane can directly be related to those in liquid water. (authors)

Solubility of amphotericin B in water-lecithin-dispersions and lecithin-based submicron emulsions.

Science.gov (United States)

Salerno, Claudia; Perez, Sebastian; Monteagudo, Ezequiel; Carlucci, Adriana; Bregni, Carlos

2013-01-01

The aim of this work was to evaluate water-lecithin-dispersions (WLDs) as carriers for amphotericin B (AmB) and to compare the drug solubility in WLDs and O/W lecithin-based submicron emulsions (SMEs) in order to evaluate the influence of lecithin content on the dosage form solubilization of the active compound. WLDs and different SMEs with either 1.2 or 2.4% of lecithin were prepared. WLD with 2.4% lecithin show a 10-fold increase in solubilization of AmB compared with 1.2% lecithin WLD. SMEs with 1.2% lecithin show an increase of over 400 times in solubilization compared with WLD containing the same concentration of lecithin, whereas SMEs with 2.4% lecithin show an increase of over 40 times compared with the corresponding WLD. Drug solubilization in SMEs with 2.4% lecithin is not significantly greater than in those containing 1.2% lecithin. The content of surfactant Brij 97 ® had a significant influence on drug solubilization in SMEs (P < 0.05). Results indicate that indicate that SMEs are proper systems to solubilize AmB. It can be assumed that solubilization is due to the formulation microstructure and not to the separate components themselves.

Cavity cooling of an optically levitated submicron particle

Science.gov (United States)

Kiesel, Nikolai; Blaser, Florian; Delić, Uroš; Grass, David; Kaltenbaek, Rainer; Aspelmeyer, Markus

2013-01-01

The coupling of a levitated submicron particle and an optical cavity field promises access to a unique parameter regime both for macroscopic quantum experiments and for high-precision force sensing. We report a demonstration of such controlled interactions by cavity cooling the center-of-mass motion of an optically trapped submicron particle. This paves the way for a light–matter interface that can enable room-temperature quantum experiments with mesoscopic mechanical systems. PMID:23940352

Surface modification of submicronic TiO{sub 2} particles prepared by ultrasonic spray pyrolysis for visible light absorption

Energy Technology Data Exchange (ETDEWEB)

Dugandzic, Ivan M. [Institute of Technical Sciences of SASA (Serbia); Jovanovic, Dragana J. [University of Belgrade, Vinca Institute of Nuclear Sciences (Serbia); Mancic, Lidija T. [Institute of Technical Sciences of SASA (Serbia); Zheng, Nan; Ahrenkiel, Scott P. [South Dakota School of Mines and Technology (United States); Milosevic, Olivera B. [Institute of Technical Sciences of SASA (Serbia); Saponjic, Zoran V.; Nedeljkovic, Jovan M., E-mail: jovned@vinca.rs [University of Belgrade, Vinca Institute of Nuclear Sciences (Serbia)

2012-10-15

Spherical, submicronic TiO{sub 2} assemblage with high specific surface area and controllable phase composition was prepared in the process of ultrasonic spray drying/pyrolysis in a wide temperature range (150-800 Degree-Sign C) by using as a precursor aqueous colloidal solution consisting of TiO{sub 2} nanoparticles (4.5 nm). Submicronic, soft and grained spherical TiO{sub 2} particles (d = 370-500 nm) comprising clustered nanocrystals (<10 nm) were obtained at low processing temperature, while particle densification, intensive growth of the clustered primary units and anatase-to-rutile transformation ({approx}30 wt%) were observed at the higher temperatures. Detailed structural and morphological characterisation were performed by X-ray powder diffraction, scanning and field emission electron microscopy, transmission electron microscopy, and laser particle size analysis. Moreover, the surface modification of TiO{sub 2} particles through the formation of charge-transfer (CT) complex was achieved with different ligands: ascorbic acid, dopamine, catechol, 2,3-dihydroxynaphthalene, and anthrarobin. Optical properties of the surface-modified TiO{sub 2} particles were studied by using diffuse reflection spectroscopy. The binding structure between the surface titanium atoms and different ligands was determined by using Fourier transform infrared spectroscopy. The formation of CT complexes induced significant red shift of optical absorption in comparison to unmodified TiO{sub 2} particles.

Energy and charge transfer in ionized argon coated water clusters

International Nuclear Information System (INIS)

Kočišek, J.; Lengyel, J.; Fárník, M.; Slavíček, P.

2013-01-01

We investigate the electron ionization of clusters generated in mixed Ar-water expansions. The electron energy dependent ion yields reveal the neutral cluster composition and structure: water clusters fully covered with the Ar solvation shell are formed under certain expansion conditions. The argon atoms shield the embedded (H 2 O) n clusters resulting in the ionization threshold above ≈15 eV for all fragments. The argon atoms also mediate more complex reactions in the clusters: e.g., the charge transfer between Ar + and water occurs above the threshold; at higher electron energies above ∼28 eV, an excitonic transfer process between Ar + * and water opens leading to new products Ar n H + and (H 2 O) n H + . On the other hand, the excitonic transfer from the neutral Ar* state at lower energies is not observed although this resonant process was demonstrated previously in a photoionization experiment. Doubly charged fragments (H 2 O) n H 2 2+ and (H 2 O) n 2+ ions are observed and Intermolecular Coulomb decay (ICD) processes are invoked to explain their thresholds. The Coulomb explosion of the doubly charged cluster formed within the ICD process is prevented by the stabilization effect of the argon solvent

A Novel Submicron Emulsion System Loaded with Doxorubicin Overcome Multi-Drug Resistance in MCF-7/ADR Cells.

Science.gov (United States)

Zhou, W P; Hua, H Y; Sun, P C; Zhao, Y X

2015-01-01

The purpose of the present study was to develop the Solutol HS15-based doxorubicin submicron emulsion with good stability and overcoming multi-drug resistance. In this study, we prepared doxorubicin submicron emulsion, and examined the stability after autoclaving, the in vitro cytotoxic activity, the intracellular accumulation and apoptpsis of doxorubicin submicron emulsion in MCF-7/ADR cells. The physicochemical properties of doxorubicin submicron emulsion were not significantly affected after autoclaving. The doxorubicin submicron emulsion significantly increased the intracellular accumulation of doxorubicin submicron emulsion and enhanced cytotoxic activity and apoptotic effects of doxorubicin. These results may be correlated to doxorubicin submicron emulsion inhibitory effects on efflux pumps through the progressive release of intracellular free Solutol HS15 from doxorubicin submicron emulsion. Furthermore, these in vitro results suggest that the Solutol HS15-based submicron emulsion may be a potentially useful drug delivery system to circumvent multi-drug resistance of tumor cells.

Ionization and fragmentation of water clusters by fast highly charged ions

International Nuclear Information System (INIS)

Adoui, L; Cassimi, A; Gervais, B; Grandin, J-P; Guillaume, L; Maisonny, R; Legendre, S; Tarisien, M; Lopez-Tarifa, P; Alcami, M; Martin, F; Politis, M-F; Penhoat, M-A Herve du; Vuilleumier, R; Gaigeot, M-P; Tavernelli, I

2009-01-01

We study the dissociative ionization of water clusters by impact of 12 MeV/u Ni 25+ ions. Cold target recoil ion momentum spectroscopy (COLTRIMS) is used to obtain information about stability, energetics and charge mobility of the ionized water clusters. An unusual stability of the H 9 O + 4 ion is observed, which could be the signature of the so-called Eigen structure in gas-phase water clusters. From the analysis of coincidences between charged fragments, we conclude that charge mobility is very high and is responsible for the formation of protonated water clusters, (H 2 O) n H + , that dominate the mass spectrum. These results are supported by Car-Parrinello molecular dynamics and time-dependent density functional theory simulations, which also reveal the mechanisms of such mobility.

Sodium-water clusters and their role in radiation chemistry

International Nuclear Information System (INIS)

Dhar, S.; Kestner, N.R.

1988-01-01

Studies of sodium-water clusters are presented which could serve as models for the recently suggested intermediate species in the radiation chemistry of water. The ionization potentials and the lower excited states of sodium with n-water molecules are calculated by ab initio quantum chemistry methods. The ionization potential calculated at the SCF level for the water monomer is 4.10 eV, which becomes 4.34 at the MP2 correlation level. The experimental value is 4.379 ± 0.002 eV. Structural data is presented for the lower members of the sodium with n-water clusters. In addition the Hartree-Fock calculations indicate that there should be some strong charge transfer to solvent transitions at higher energies. (author)

NATO Advanced Study Institute on Physics of Submicron Semiconductor Devices

CERN Document Server

Ferry, David; Jacoboni, C

1988-01-01

The papers contained in the volume represent lectures delivered as a 1983 NATO ASI, held at Urbino, Italy. The lecture series was designed to identify the key submicron and ultrasubmicron device physics, transport, materials and contact issues. Nonequilibrium transport, quantum transport, interfacial and size constraints issues were also highlighted. The ASI was supported by NATO and the European Research Office. H. L. Grubin D. K. Ferry C. Jacoboni v CONTENTS MODELLING OF SUB-MICRON DEVICES.................. .......... 1 E. Constant BOLTZMANN TRANSPORT EQUATION... ... ...... .................... 33 K. Hess TRANSPORT AND MATERIAL CONSIDERATIONS FOR SUBMICRON DEVICES. . .. . . . . .. . . . .. . .. . .... ... .. . . . .. . . . .. . . . . . . . . . . 45 H. L. Grubin EPITAXIAL GROWTH FOR SUB MICRON STRUCTURES.................. 179 C. E. C. Wood INSULATOR/SEMICONDUCTOR INTERFACES.......................... 195 C. W. Wilms en THEORY OF THE ELECTRONIC STRUCTURE OF SEMICONDUCTOR SURFACES AND INTERFACES...................

Bloch-Wave Engineered Submicron Diameter Micropillars with Quality Factors Exceeding 10,000

DEFF Research Database (Denmark)

Hofling, S.; Lermer, M.; Gregersen, Niels

2011-01-01

Adiabatic design submicron diameter quantum-dot micropillars have been designed and implemented for cavity quantum electrodynamics experiments. Ultra-high experimental quality factors (>10,000) are obtained for submicron diameters and strong light-matter interaction is observed....

Structure and stability of spiro-cyclic water clusters

Indian Academy of Sciences (India)

Administrator

Abstract. The structure and stability of spiro-cyclic water clusters containing up to 32 water molecules have been ... due to its importance in various real life systems. 1–8. High level ... It is well-known from the crystal structure data- base that the ...

An introduction to deep submicron CMOS for vertex applications

CERN Document Server

Campbell, M; Cantatore, E; Faccio, F; Heijne, Erik H M; Jarron, P; Santiard, Jean-Claude; Snoeys, W; Wyllie, K

2001-01-01

Microelectronics has become a key enabling technology in the development of tracking detectors for High Energy Physics. Deep submicron CMOS is likely to be extensively used in all future tracking systems. Radiation tolerance in the Mrad region has been achieved and complete readout chips comprising many millions of transistors now exist. The choice of technology is dictated by market forces but the adoption of deep submicron CMOS for tracking applications still poses some challenges. The techniques used are reviewed and some of the future challenges are discussed.

Cost-effectiveness of Low-dose Submicron Diclofenac Compared With Generic Diclofenac.

Science.gov (United States)

Mladsi, Deirdre; Ronquest, Naoko; Odom, Dawn; Miles, LaStella; Saag, Kenneth

2016-11-01

NSAIDs are commonly prescribed for the treatment of pain and inflammation. Despite the effectiveness of NSAIDs, concerns exist regarding their tolerability. Worldwide health authorities, including the European Medicines Agency, Health Canada, and the US Food and Drug Administration, have advised that NSAIDs be prescribed at the lowest effective dosage and for the shortest duration. Effective lowering of NSAID dosage without compromising pain relief has been demonstrated in randomized, controlled trials of the recently approved NSAID lower-dose submicron diclofenac. Building on previously published work from an independently published systematic review and meta-analysis, a linear dose-toxicity relationship between diclofenac dose and serious gastrointestinal (GI) events was recently demonstrated, indicating that reductions in adverse events (AEs) may be seen even with modest dose reductions in many patients. The objective of the present study was to estimate the potential reduction in risk for NSAID dose-related AEs, corresponding savings in health care costs, and the incremental cost-effectiveness of submicron diclofenac compared with generic diclofenac in the United States. Our decision-analytic cost-effectiveness model considered a subset of potential AEs that may be avoided by lowering NSAID dosage. To estimate the expected reductions in upper GI bleeding/perforation and major cardiovascular events with submicron diclofenac, our model used prediction equations estimated by meta-regressions using data from systematic literature reviews. Utilities, lifetime costs, and health outcomes associated with AEs were estimated using data from the literature. The face validity of the model structure and inputs was confirmed by clinical experts in the United States. Results were evaluated in 1-way and probabilistic sensitivity analyses. The model predicted that submicron diclofenac versus generic diclofenac could reduce the occurrence of modeled GI events (by 18

Scanning SQUID susceptometers with sub-micron spatial resolution

Energy Technology Data Exchange (ETDEWEB)

Kirtley, John R., E-mail: jkirtley@stanford.edu; Rosenberg, Aaron J.; Palmstrom, Johanna C.; Holland, Connor M.; Moler, Kathryn A. [Department of Applied Physics, Stanford University, Stanford, California 94305-4045 (United States); Paulius, Lisa [Department of Physics, Western Michigan University, Kalamazoo, Michigan 49008-5252 (United States); Spanton, Eric M. [Department of Physics, Stanford University, Stanford, California 94305-4045 (United States); Schiessl, Daniel [Attocube Systems AG, Königinstraße 11A, 80539 Munich (Germany); Jermain, Colin L.; Gibbons, Jonathan [Department of Physics, Cornell University, Cornell, Ithaca, New York 14853 (United States); Fung, Y.-K.K.; Gibson, Gerald W. [IBM Research Division, T. J. Watson Research Center, Yorktown Heights, New York 10598 (United States); Huber, Martin E. [Department of Physics, University of Colorado Denver, Denver, Colorado 80217-3364 (United States); Ralph, Daniel C. [Department of Physics, Cornell University, Cornell, Ithaca, New York 14853 (United States); Kavli Institute at Cornell, Ithaca, New York 14853 (United States); Ketchen, Mark B. [OcteVue, Hadley, Massachusetts 01035 (United States)

2016-09-15

Superconducting QUantum Interference Device (SQUID) microscopy has excellent magnetic field sensitivity, but suffers from modest spatial resolution when compared with other scanning probes. This spatial resolution is determined by both the size of the field sensitive area and the spacing between this area and the sample surface. In this paper we describe scanning SQUID susceptometers that achieve sub-micron spatial resolution while retaining a white noise floor flux sensitivity of ≈2μΦ{sub 0}/Hz{sup 1/2}. This high spatial resolution is accomplished by deep sub-micron feature sizes, well shielded pickup loops fabricated using a planarized process, and a deep etch step that minimizes the spacing between the sample surface and the SQUID pickup loop. We describe the design, modeling, fabrication, and testing of these sensors. Although sub-micron spatial resolution has been achieved previously in scanning SQUID sensors, our sensors not only achieve high spatial resolution but also have integrated modulation coils for flux feedback, integrated field coils for susceptibility measurements, and batch processing. They are therefore a generally applicable tool for imaging sample magnetization, currents, and susceptibilities with higher spatial resolution than previous susceptometers.

Scanning SQUID susceptometers with sub-micron spatial resolution

International Nuclear Information System (INIS)

Kirtley, John R.; Rosenberg, Aaron J.; Palmstrom, Johanna C.; Holland, Connor M.; Moler, Kathryn A.; Paulius, Lisa; Spanton, Eric M.; Schiessl, Daniel; Jermain, Colin L.; Gibbons, Jonathan; Fung, Y.-K.K.; Gibson, Gerald W.; Huber, Martin E.; Ralph, Daniel C.; Ketchen, Mark B.

2016-01-01

Superconducting QUantum Interference Device (SQUID) microscopy has excellent magnetic field sensitivity, but suffers from modest spatial resolution when compared with other scanning probes. This spatial resolution is determined by both the size of the field sensitive area and the spacing between this area and the sample surface. In this paper we describe scanning SQUID susceptometers that achieve sub-micron spatial resolution while retaining a white noise floor flux sensitivity of ≈2μΦ_0/Hz"1"/"2. This high spatial resolution is accomplished by deep sub-micron feature sizes, well shielded pickup loops fabricated using a planarized process, and a deep etch step that minimizes the spacing between the sample surface and the SQUID pickup loop. We describe the design, modeling, fabrication, and testing of these sensors. Although sub-micron spatial resolution has been achieved previously in scanning SQUID sensors, our sensors not only achieve high spatial resolution but also have integrated modulation coils for flux feedback, integrated field coils for susceptibility measurements, and batch processing. They are therefore a generally applicable tool for imaging sample magnetization, currents, and susceptibilities with higher spatial resolution than previous susceptometers.

Ab initio theoretical calculations of the electronic excitation energies of small water clusters.

Science.gov (United States)

Tachikawa, Hiroto; Yabushita, Akihiro; Kawasaki, Masahiro

2011-12-14

A direct ab initio molecular dynamics method has been applied to a water monomer and water clusters (H(2)O)(n) (n = 1-3) to elucidate the effects of zero-point energy (ZPE) vibration on the absorption spectra of water clusters. Static ab initio calculations without ZPE showed that the first electronic transitions of (H(2)O)(n), (1)B(1)←(1)A(1), are blue-shifted as a function of cluster size (n): 7.38 eV (n = 1), 7.58 eV (n = 2) and 8.01 eV (n = 3). The inclusion of the ZPE vibration strongly affects the excitation energies of a water dimer, and a long red-tail appears in the range of 6.42-6.90 eV due to the structural flexibility of a water dimer. The ultraviolet photodissociation of water clusters and water ice surfaces is relevant to these results.

Vacuum-ultraviolet (VUV) photoionization of small methanol and methanol-water clusters

International Nuclear Information System (INIS)

Ahmed, Musahid; Ahmed, Musahid; Wilson, Kevin R.; Belau, Leonid; Kostko, Oleg

2008-01-01

In this work we report on the vacuum-ultraviolet (VUV) photoionization of small methanol and methanol-water clusters. Clusters of methanol with water are generated via co-expansion of the gas phase constituents in a continuous supersonic jet expansion of methanol and water seeded in Ar. The resulting clusters are investigated by single photon ionization with tunable vacuum ultraviolet synchrotron radiation and mass analyzed using reflectron mass spectrometry. Protonated methanol clusters of the form (CH3OH)nH + (n=1-12) dominate the mass spectrum below the ionization energy of the methanol monomer. With an increase in water concentration, small amounts of mixed clusters of the form (CH3OH)n(H2O)H + (n=2-11) are detected. The only unprotonated species observed in this work are the methanol monomer and dimer. Appearance energies are obtained from the photoionization efficiency (PIE) curves for CH3OH +, (CH 3OH)2 +, (CH3OH)nH + (n=1-9), and (CH 3OH)n(H2O)H + (n=2-9 ) as a function of photon energy. With an increase in the water content in the molecular beam, there is an enhancement of photoionization intensity for methanol dimer and protonated methanol monomer at threshold. These results are compared and contrasted to previous experimental observations

Submicron Resolution Spectral-Domain Optical Coherence Tomography

KAUST Repository

Alarousu, Erkki; Jabbour, Ghassan

2013-01-01

Apparatuses and systems for submicron resolution spectral-domain optical coherence tomography (OCT) are disclosed. The system may use white light sources having wavelengths within 400-1000 nanometers, and achieve resolution below 1 .mu

The role of jet and film drops in controlling the mixing state of submicron sea spray aerosol particles

Energy Technology Data Exchange (ETDEWEB)

Wang, Xiaofei; Deane, Grant B.; Moore, Kathryn A.; Ryder, Olivia S.; Stokes, M. Dale; Beall, Charlotte M.; Collins, Douglas B.; Santander, Mitchell V.; Burrows, Susannah M.; Sultana, Camille M.; Prather, Kimberly A.

2017-06-19

Covering 71% of the Earth’s surface, oceans represent a significant global source of atmospheric aerosols. The size and composition of sea spray aerosols (SSA) affect their ability to serve as cloud seeds and thus understanding the factors controlling their composition is critical to predicting their impact on clouds and climate. SSA particles have been shown to be an external mixture of particles with different compositions. Film and jet drop production mechanisms ultimately determine the individual particle compositions which are comprised of an array of salt/organic mixtures ranging from pure sea salt to nearly pure organic particles. It is often assumed that the majority of submicron SSA are formed by film drops produced from bursting hydrophobic organic-rich bubble film caps at the sea surface, and in contrast, jet drops are postulated to produce larger supermicron particles from underlying seawater comprised largely of salts and water soluble organic species. However, here we show that jet drops produced by bursting sub-100 m bubbles account for up to 40 % of all submicron particles. They have distinct chemical compositions, organic volume fractions and ice nucleating activities from submicron film drops. Thus a substantial fraction of submicron particles will not necessarily be controlled by the composition of the sea surface microlayer as has been assumed in many studies. This finding has significant ramifications for the size-resolved mixing states of SSA particles which must be taken into consideration when accessing SSA impacts on clouds.

Dual effects of water vapor on ceria-supported gold clusters.

Science.gov (United States)

Li, Zhimin; Li, Weili; Abroshan, Hadi; Ge, Qingjie; Li, Gao; Jin, Rongchao

2018-04-05

Atomically precise nanocatalysts are currently being intensely pursued in catalysis research. Such nanocatalysts can serve as model catalysts for gaining fundamental insights into catalytic processes. In this work we report a discovery that water vapor provokes the mild removal of surface long-chain ligands on 25-atom Au25(SC12H25)18 nanoclusters in a controlled manner. Using the resultant Au25(SC12H25)18-x/CeO2 catalyst and CO oxidation as a probe reaction, we found that the catalytic activity of cluster/CeO2 is enhanced from nearly zero conversion of CO (in the absence of water) to 96.2% (in the presence of 2.3 vol% H2O) at the same temperature (100 °C). The cluster catalysts exhibit high stability during the CO oxidation process under moisture conditions (up to 20 vol% water vapor). Water vapor plays a dual role in gold cluster-catalyzed CO oxidation. FT-IR and XPS analyses in combination with density functional theory (DFT) simulations suggest that the "-SC12H25" ligands are easier to be removed under a water vapor atmosphere, thus generating highly active sites. Moreover, the O22- peroxide species constitutes the active oxygen species in CO oxidation, evidenced by Raman spectroscopy analysis and isotope experiments on the CeO2 and cluster/CeO2. The results also indicate the perimeter sites of the interface of Au25(SC12H25)18-x/CeO2 to be active sites for catalytic CO oxidation. The controlled exposure of active sites under mild conditions is of critical importance for the utilization of clusters in catalysis.

Use of metallic glasses for fabrication of structures with submicron dimensions

Science.gov (United States)

Wiley, John D.; Perepezko, John H.

1986-01-01

Patterned structures of submicron dimension formed of supported or unsupported amorphous metals having submicron feature sizes characterized by etching behavior sufficient to allow delineation of sharp edges and smooth flat flanks, resistance to time-dependent dimensional changes caused by creep, flow, in-diffusion of unwanted impurities, out-diffusion of constituent atoms, void formation, grain growth or phase separation and resistance to phase transformations or compound formation.

Structures, Energetics and Spectroscopic Fingerprints of Water Clusters n=2-24

Energy Technology Data Exchange (ETDEWEB)

Yoo, Soohaeng; Xantheas, Sotiris S.

2017-06-08

This chapter discusses the structures, energetics, and vibrational spectra of the first few (n$24) water clusters obtained from high-level electronic structure calculations. The results are discussed in the perspective of being used to parameterize/assess the accuracy of classical and quantum force fields for water. To this end, a general introduction with the classification of those force fields is presented. Several low-lying families of minima for the medium cluster sizes are considered. The transition from the “all surface” to the “fully coordinated” cluster structures occurring at nD17 and its spectroscopic signature is presented. The various families of minima for nD20 are discussed together with the low energy networks of the pentagonal dodecahedron (H2O)20 water cage. Finally, the low-energy networks of the tetrakaidecahedron (T-cage) (H2O)24 cluster are shown and their significance in the construction of periodic lattices of structure I (sI) of the hydrate lattices is discussed.

Hierarchy of the Collective Effects in Water Clusters.

Science.gov (United States)

Bakó, Imre; Mayer, István

2016-02-04

The results of dipole moment as well as of intra- and intermolecular bond order calculations indicate the big importance of collective electrostatic effects caused by the nonimmediate environment in liquid water models. It is also discussed how these collective effects are built up as consequences of the electrostatic and quantum chemical interactions in water clusters.

Electrosprayed Polyvinylpyrrolidone (PVP) Submicron Particles Loaded by Green Tea Extracts

Science.gov (United States)

Kamaruddin; Sriyanti, I.; Edikresnha, D.; Munir, M. M.; Khairurrijal, K.

2018-05-01

Electrospraying technique has been successfully used to synthesize composite submicron particles of polyvinylpyrrolidone (PVP) and green tea extract (GTE). The precursor solutions were PVP in ethanol (15 wt%) and GTE in ethanol (10 wt%), which were then mixed at varying ratio. The mixed solution then underwent electrospraying process at an applied voltage of 15 kV, a distance of collector to the nozzle at 15 cm, and a flow rate of 3 µL/min. The composite submicron particles of PVP-GTE showed smooth and fine spherical morphology without fibers or beaded fibers. To a certain degree, the increase of GTE content in the PVP-GTE mixed solution decreased the average diameter of PVP-GTE composite particles. Moreover, the analysis of the FTIR spectra confirmed the existing molecular interaction between PVP and GTE in the composite submicron particles as shown by the shift of PVP wavenumber towards GTE, which has typically smaller wavenumber.

Fabrication, microstructure, and mechanical properties of high strength cobalt sub-micron structures

International Nuclear Information System (INIS)

Jin Sumin; Burek, Michael J.; Evans, Robert D.; Jahed, Zeinab; Leung, Michael C.; Evans, Neal D.; Tsui, Ting Y.

2012-01-01

The mechanical properties exhibited by sub-micron scale columnar structures of cobalt, fabricated by electron beam lithography and electroplating techniques, were investigated through uniaxial compression. Transmission electron microscopy analyses show these specimens possess a microstructure with sub-micron grains which are elongated and aligned near to the pillar loading axis. In addition, small nanocrystalline cobalt crystals are also present within the columnar structure. These specimens display exceptional mechanical strength comparable with both bulk polycrystalline and nanocrystalline cobalt deposited by electroplating. Size-dependent softening with shrinking sample dimensions is also observed in this work. Additionally, the strength of these sub-micron structures appears to be strain rate sensitive and comparable with bulk nanocrystalline cobalt specimens.

Deposition of metal Islands, metal clusters and metal containing single molecules on self-assembled monolayers

NARCIS (Netherlands)

Speets, Emiel Adrianus

2005-01-01

The central topic of this thesis is the deposition of metals on Self-Assembled Monolayers (SAMs). Metals are deposited in the form of submicron scale islands, nanometer scale clusters, and as supramolecular, organometallic coordination cages. Several SAMs on various substrates were prepared and

High density submicron magnetoresistive random access memory (invited)

Science.gov (United States)

Tehrani, S.; Chen, E.; Durlam, M.; DeHerrera, M.; Slaughter, J. M.; Shi, J.; Kerszykowski, G.

1999-04-01

Various giant magnetoresistance material structures were patterned and studied for their potential as memory elements. The preferred memory element, based on pseudo-spin valve structures, was designed with two magnetic stacks (NiFeCo/CoFe) of different thickness with Cu as an interlayer. The difference in thickness results in dissimilar switching fields due to the shape anisotropy at deep submicron dimensions. It was found that a lower switching current can be achieved when the bits have a word line that wraps around the bit 1.5 times. Submicron memory elements integrated with complementary metal-oxide-semiconductor (CMOS) transistors maintained their characteristics and no degradation to the CMOS devices was observed. Selectivity between memory elements in high-density arrays was demonstrated.

High intensity laser interactions with sub-micron droplets

International Nuclear Information System (INIS)

Mountford, L.C.

1999-01-01

A high-density source of liquid ethanol droplets has been developed, characterised and used in laser interaction studies for the first time. Mie Scattering and attenuation measurements show that droplets with a radius of (0.5 ± 0.1) μm and atomic densities of 10 19 atoms/cm 3 can be produced, bridging the gap between clusters and macroscopic solids. Lower density (10 16 cm -3 ) sprays can also be produced and these are electrostatically split into smaller droplets with a radius of (0.3 ± 0.1) μm. This work has been accepted for publication in Review of Scientific Instruments. A range of high intensity interaction experiments have been carried out with this unique sub-micron source. The absolute yield of keV x-rays, generated using 527 nm, 2 ps pulses focused to ∼10 17 W/cm 2 , was measured for the first time. ∼7 μJ of x-rays with photon energies above 1 keV were produced, comparable to yields obtained from much higher Z Xenon clusters. At intensities ≤10 16 W/cm 2 the yield from droplets exceeds that from solid targets of similar Z. The droplet medium is debris free and self-renewing, providing a suitable x-ray source for lithographic techniques. Due to the spacing between the droplets, it was expected that the droplet plasma temperature would exceed that of a solid target plasma, which is typically limited by rapid heat conduction to <1 keV. Analysis of the x-ray data shows this to be true with a mean droplet plasma temperature of (2 ± 0.8) keV, and a number of measurements exceeding 5 keV (to appear in Applied Physics Letters). The absorption of high intensity laser pulses in the dense spray has been measured for the first time and this was found to be wavelength and polarisation independent and in excess of 60%. These first interaction measurements clearly indicate that there are significant differences between the laser heating of droplet, solid and cluster targets. (author)

Effects of solvation shells and cluster size on the reaction of aluminum clusters with water

Directory of Open Access Journals (Sweden)

Weiwei Mou

2011-12-01

Full Text Available Reaction of aluminum clusters, Aln (n = 16, 17 and 18, with liquid water is investigated using quantum molecular dynamics simulations, which show rapid production of hydrogen molecules assisted by proton transfer along a chain of hydrogen bonds (H-bonds between water molecules, i.e. Grotthuss mechanism. The simulation results provide answers to two unsolved questions: (1 What is the role of a solvation shell formed by non-reacting H-bonds surrounding the H-bond chain; and (2 whether the high size-selectivity observed in gas-phase Aln-water reaction persists in liquid phase? First, the solvation shell is found to play a crucial role in facilitating proton transfer and hence H2 production. Namely, it greatly modifies the energy barrier, generally to much lower values (< 0.1 eV. Second, we find that H2 production by Aln in liquid water does not depend strongly on the cluster size, in contrast to the existence of magic numbers in gas-phase reaction. This paper elucidates atomistic mechanisms underlying these observations.

An efficient venturi scrubber system to remove submicron particles in exhaust gas.

Science.gov (United States)

Tsai, Chuen-Jinn; Lin, Chia-Hung; Wang, Yu-Min; Hunag, Cheng-Hsiung; Li, Shou-Nan; Wu, Zong-Xue; Wang, Feng-Cai

2005-03-01

An efficient venturi scrubber system making use of heterogeneous nucleation and condensational growth of particles was designed and tested to remove fine particles from the exhaust of a local scrubber where residual SiH4 gas was abated and lots of fine SiO2 particles were generated. In front of the venturi scrubber, normal-temperature fine-water mist mixes with high-temperature exhaust gas to cool it to the saturation temperature, allowing submicron particles to grow into micron sizes. The grown particles are then scrubbed efficiently in the venturi scrubber. Test results show that the present venturi scrubber system is effective for removing submicron particles. For SiO2 particles greater than 0.1microm, the removal efficiency is greater than 80-90%, depending on particle concentration. The corresponding pressure drop is relatively low. For example, the pressure drop of the venturi scrubber is approximately 15.4 +/- 2.4 cm H2O when the liquid-to-gas ratio is 1.50 L/m3. A theoretical calculation has been conducted to simulate particle growth process and the removal efficiency of the venturi scrubber. The theoretical results agree with the experimental data reasonably well when SiO2 particle diameter is greater than 0.1 microm.

SUBMICRON PARTICLES EMISSION CONTROL BY ELECTROSTATIC AGGLOMERATION

Directory of Open Access Journals (Sweden)

Andrzej Krupa

2017-04-01

Full Text Available The aim of the study was to develop a device for more effective treatment of flue gases from submicron particles emitted by power plants burning bituminous coal and by this way the reduction of environment pollution. Electrostatic processes were employed to this goal, as the most effective solution. The solutions hitherto applied in electrostatic precipitation techniques were designed for large particles, typically with sizes> 5 µm, which are easily removed by the action of electrostatic force on the electrically charged particles. In submicron size range (0.1-1 µm the collection efficiency of an ESP is minimal, because of the low value of electric charge on such particles. In order to avoid problems with the removal of submicron particles of fly ash from the flue gases electrostatic agglomeration has been used. In this process, by applying an alternating electric field, larger charged particles (> 1 µm oscillate, and the particles "collect" smaller uncharged particles. In the developed agglomerator with alternating electric field, the charging of particles and the coagulation takes place in one stage that greatly simplified the construction of the device, compared to other solutions. The scope of this study included measurements of fractional collection efficiency of particles in the system comprising of agglomerator and ESP for PM1 and PM2.5 ranges, in device made in pilot scale. The collection efficiency for PM2.5 was greater than 90% and PM1 slightly dropped below 90%. The mass collection efficiency for PM2.5 was greater than 95%. The agglomerator stage increases the collection efficiency for PM1 at a level of 5-10%.

Electron beam fabrication of a microfluidic device for studying submicron-scale bacteria

Science.gov (United States)

2013-01-01

Background Controlled restriction of cellular movement using microfluidics allows one to study individual cells to gain insight into aspects of their physiology and behaviour. For example, the use of micron-sized growth channels that confine individual Escherichia coli has yielded novel insights into cell growth and death. To extend this approach to other species of bacteria, many of whom have dimensions in the sub-micron range, or to a larger range of growth conditions, a readily-fabricated device containing sub-micron features is required. Results Here we detail the fabrication of a versatile device with growth channels whose widths range from 0.3 μm to 0.8 μm. The device is fabricated using electron beam lithography, which provides excellent control over the shape and size of different growth channels and facilitates the rapid-prototyping of new designs. Features are successfully transferred first into silicon, and subsequently into the polydimethylsiloxane that forms the basis of the working microfluidic device. We demonstrate that the growth of sub-micron scale bacteria such as Lactococcus lactis or Escherichia coli cultured in minimal medium can be followed in such a device over several generations. Conclusions We have presented a detailed protocol based on electron beam fabrication together with specific dry etching procedures for the fabrication of a microfluidic device suited to study submicron-sized bacteria. We have demonstrated that both Gram-positive and Gram-negative bacteria can be successfully loaded and imaged over a number of generations in this device. Similar devices could potentially be used to study other submicron-sized organisms under conditions in which the height and shape of the growth channels are crucial to the experimental design. PMID:23575419

Ionization of water clusters by fast Highly Charged Ions: Stability, fragmentation, energetics and charge mobility

International Nuclear Information System (INIS)

Legendre, S; Maisonny, R; Capron, M; Bernigaud, V; Cassimi, A; Gervais, B; Grandin, J-P; Huber, B A; Manil, B; Rousseau, P; Tarisien, M; Adoui, L; Lopez-Tarifa, P; AlcamI, M; MartIn, F; Politis, M-F; Penhoat, M A Herve du; Vuilleumier, R; Gaigeot, M-P; Tavernelli, I

2009-01-01

We study dissociative ionization of water clusters by impact of fast Ni ions. Cold Target Recoil Ion Momentum Spectroscopy (COLTRIMS) is used to obtain information about stability, energetics and charge mobility of the ionized clusters. An unusual stability of the (H 2 O) 4 H ''+ ion is observed, which could be the signature of the so called ''Eigen'' structure in gas phase water clusters. High charge mobility, responsible for the formation of protonated water clusters that dominate the mass spectrum, is evidenced. These results are supported by CPMD and TDDFT simulations, which also reveal the mechanisms of such mobility.

Photo-stimulated desorption from water and methane clusters on the surface of solid neon

International Nuclear Information System (INIS)

Arakawa Ichiri; Matsumoto Dairo; Takekuma Shinichi; Tamura Reimi; Miura Takashi

2012-01-01

Photo-stimulated desorption of ions from methane and water heterocluster on the surface of solid neon was studied. The desorption yields of the variety of photo-desorbed species showed strong dependence on the composition and the size of the mother cluster. It was found that the presence of a water molecule in the cluster significantly enhanced, or was almost essential for, the desorption of any species observed. Systematic investigation of the correlation between the cluster size and the desorption yield of each ion has revealed the mother cluster which yields the each desorbed ion.

Development of an interdisciplinary model cluster for tidal water environments

Science.gov (United States)

Dietrich, Stephan; Winterscheid, Axel; Jens, Wyrwa; Hartmut, Hein; Birte, Hein; Stefan, Vollmer; Andreas, Schöl

2013-04-01

Global climate change has a high potential to influence both the persistence and the transport pathways of water masses and its constituents in tidal waters and estuaries. These processes are linked through dispersion processes, thus directly influencing the sediment and solid suspend matter budgets, and thus the river morphology. Furthermore, the hydrologic regime has an impact on the transport of nutrients, phytoplankton, suspended matter, and temperature that determine the oxygen content within water masses, which is a major parameter describing the water quality. This project aims at the implementation of a so-called (numerical) model cluster in tidal waters, which includes the model compartments hydrodynamics, morphology and ecology. For the implementation of this cluster it is required to continue with the integration of different models that work in a wide range of spatial and temporal scales. The model cluster is thus suggested to lead to a more precise knowledge of the feedback processes between the single interdisciplinary model compartments. In addition to field measurements this model cluster will provide a complementary scientific basis required to address a spectrum of research questions concerning the integral management of estuaries within the Federal Institute of Hydrology (BfG, Germany). This will in particular include aspects like sediment and water quality management as well as adaptation strategies to climate change. The core of the model cluster will consist of the 3D-hydrodynamic model Delft3D (Roelvink and van Banning, 1994), long-term hydrodynamics in the estuaries are simulated with the Hamburg Shelf Ocean Model HAMSOM (Backhaus, 1983; Hein et al., 2012). The simulation results will be compared with the unstructured grid based SELFE model (Zhang and Bapista, 2008). The additional coupling of the BfG-developed 1D-water quality model QSim (Kirchesch and Schöl, 1999; Hein et al., 2011) with the morphological/hydrodynamic models is an

Aggregation Number in Water/n-Hexanol Molecular Clusters Formed in Cyclohexane at Different Water/n-Hexanol/Cyclohexane Compositions Calculated by Titration 1H NMR.

Science.gov (United States)

Flores, Mario E; Shibue, Toshimichi; Sugimura, Natsuhiko; Nishide, Hiroyuki; Moreno-Villoslada, Ignacio

2017-11-09

Upon titration of n-hexanol/cyclohexane mixtures of different molar compositions with water, water/n-hexanol clusters are formed in cyclohexane. Here, we develop a new method to estimate the water and n-hexanol aggregation numbers in the clusters that combines integration analysis in one-dimensional 1 H NMR spectra, diffusion coefficients calculated by diffusion-ordered NMR spectroscopy, and further application of the Stokes-Einstein equation to calculate the hydrodynamic volume of the clusters. Aggregation numbers of 5-15 molecules of n-hexanol per cluster in the absence of water were observed in the whole range of n-hexanol/cyclohexane molar fractions studied. After saturation with water, aggregation numbers of 6-13 n-hexanol and 0.5-5 water molecules per cluster were found. O-H and O-O atom distances related to hydrogen bonds between donor/acceptor molecules were theoretically calculated using density functional theory. The results show that at low n-hexanol molar fractions, where a robust hydrogen-bond network is held between n-hexanol molecules, addition of water makes the intermolecular O-O atom distance shorter, reinforcing molecular association in the clusters, whereas at high n-hexanol molar fractions, where dipole-dipole interactions dominate, addition of water makes the intermolecular O-O atom distance longer, weakening the cluster structure. This correlates with experimental NMR results, which show an increase in the size and aggregation number in the clusters upon addition of water at low n-hexanol molar fractions, and a decrease of these magnitudes at high n-hexanol molar fractions. In addition, water produces an increase in the proton exchange rate between donor/acceptor molecules at all n-hexanol molar fractions.

GW and Bethe-Salpeter study of small water clusters

Energy Technology Data Exchange (ETDEWEB)

Blase, Xavier, E-mail: xavier.blase@neel.cnrs.fr; Boulanger, Paul [CNRS, Institut NEEL, F-38042 Grenoble (France); Bruneval, Fabien [CEA, DEN, Service de Recherches de Métallurgie Physique, F-91191 Gif-sur-Yvette (France); Fernandez-Serra, Marivi [Department of Physics and Astronomy, Stony Brook University, Stony Brook, New York 11794-3800 (United States); Institute for Advanced Computational Sciences, Stony Brook University, Stony Brook, New York 11794-3800 (United States); Duchemin, Ivan [INAC, SP2M/L-Sim, CEA/UJF Cedex 09, 38054 Grenoble (France)

2016-01-21

We study within the GW and Bethe-Salpeter many-body perturbation theories the electronic and optical properties of small (H{sub 2}O){sub n} water clusters (n = 1-6). Comparison with high-level CCSD(T) Coupled-Cluster at the Single Double (Triple) levels and ADC(3) Green’s function third order algebraic diagrammatic construction calculations indicates that the standard non-self-consistent G{sub 0}W{sub 0}@PBE or G{sub 0}W{sub 0}@PBE0 approaches significantly underestimate the ionization energy by about 1.1 eV and 0.5 eV, respectively. Consequently, the related Bethe-Salpeter lowest optical excitations are found to be located much too low in energy when building transitions from a non-self-consistent G{sub 0}W{sub 0} description of the quasiparticle spectrum. Simple self-consistent schemes, with update of the eigenvalues only, are shown to provide a weak dependence on the Kohn-Sham starting point and a much better agreement with reference calculations. The present findings rationalize the theory to experiment possible discrepancies observed in previous G{sub 0}W{sub 0} and Bethe-Salpeter studies of bulk water. The increase of the optical gap with increasing cluster size is consistent with the evolution from gas to dense ice or water phases and results from an enhanced screening of the electron-hole interaction.

First evidence of a water-soluble plutonium(IV) hexanuclear cluster

Energy Technology Data Exchange (ETDEWEB)

Tamain, Christelle; Dumas, Thomas; Guillaumont, Dominique; Guilbaud, Philippe [CEA, Nuclear Energy Division, Marcoule, RadioChemistry and Processes Department, Bagnols sur Ceze (France); Hennig, Christoph [Helmholtz-Zentrum Dresden-Rossendorf, Institute of Resource Ecology, Dresden (Germany)

2016-08-15

The singular Pu{sup IV} hexanuclear cluster [Pu{sub 6}(OH){sub 4}O{sub 4}]{sup 12+} stabilized by 1,4,7,10-tetraazacyclododecane-1,4,7,10-tetraacetic acid (DOTA) ligands was structurally characterized for the first time both in the solid state and in water solution by using X-ray diffraction and X-ray absorption and UV/Vis spectroscopy. The stability of this cluster in water and its high solubility over a large pH range are of upmost importance for plutonium environmental speciation with potential applications in a related migration model. (copyright 2016 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

The effect of arsenic thermal diffusion on the morphology and photoluminescence properties of sub-micron ZnO rods

Energy Technology Data Exchange (ETDEWEB)

Ding Meng [Department of Physics, Jilin University, Changchun 130023 (China); Laboratory of Excited State Processes, Changchun Institute of Optics, Fine Mechanics and Physics, Chinese Academy of Sciences, Changchun 130021 (China); Yao Bin, E-mail: binyao@jlu.edu.c [Department of Physics, Jilin University, Changchun 130023 (China); Zhao Dongxu, E-mail: dxzhao2000@yahoo.com.c [Laboratory of Excited State Processes, Changchun Institute of Optics, Fine Mechanics and Physics, Chinese Academy of Sciences, Changchun 130021 (China); Fang Fang; Shen Dezhen; Zhang Zhenzhong [Laboratory of Excited State Processes, Changchun Institute of Optics, Fine Mechanics and Physics, Chinese Academy of Sciences, Changchun 130021 (China)

2010-05-31

As-doped sub-micron ZnO rods were realized by a simple thermal diffusion process using a GaAs wafer as an arsenic resource. The surface of the sub-micron ZnO rods became rough and the morphology of As-doped sub-micron ZnO rods changed markedly with increasing diffusion temperature. From the results of energy-dispersive X-ray spectroscopy, X-ray diffraction and photoluminescence, arsenic elements were confirmed to be introduced into the sub-micron ZnO rods. The acceptor ionization energy was deduced to be about 110 meV based on the temperature-dependent PL spectra.

The effect of arsenic thermal diffusion on the morphology and photoluminescence properties of sub-micron ZnO rods

International Nuclear Information System (INIS)

Ding Meng; Yao Bin; Zhao Dongxu; Fang Fang; Shen Dezhen; Zhang Zhenzhong

2010-01-01

As-doped sub-micron ZnO rods were realized by a simple thermal diffusion process using a GaAs wafer as an arsenic resource. The surface of the sub-micron ZnO rods became rough and the morphology of As-doped sub-micron ZnO rods changed markedly with increasing diffusion temperature. From the results of energy-dispersive X-ray spectroscopy, X-ray diffraction and photoluminescence, arsenic elements were confirmed to be introduced into the sub-micron ZnO rods. The acceptor ionization energy was deduced to be about 110 meV based on the temperature-dependent PL spectra.

Light emitting diode with high aspect ratio submicron roughness for light extraction and methods of forming

Science.gov (United States)

Li, Ting [Ventura, CA

2011-04-26

The surface morphology of an LED light emitting surface is changed by applying a reactive ion etch (RIE) process to the light emitting surface. High aspect ratio, submicron roughness is formed on the light emitting surface by transferring a thin film metal hard-mask having submicron patterns to the surface prior to applying a reactive ion etch process. The submicron patterns in the metal hard-mask can be formed using a low cost, commercially available nano-patterned template which is transferred to the surface with the mask. After subsequently binding the mask to the surface, the template is removed and the RIE process is applied for time duration sufficient to change the morphology of the surface. The modified surface contains non-symmetric, submicron structures having high aspect ratio which increase the efficiency of the device.

Properties of ammonium ion-water clusters: analyses of structure evolution, noncovalent interactions, and temperature and humidity effects.

Science.gov (United States)

Pei, Shi-Tu; Jiang, Shuai; Liu, Yi-Rong; Huang, Teng; Xu, Kang-Ming; Wen, Hui; Zhu, Yu-Peng; Huang, Wei

2015-03-26

Although ammonium ion-water clusters are abundant in the biosphere, some information regarding these clusters, such as their growth route, the influence of temperature and humidity, and the concentrations of various hydrated clusters, is lacking. In this study, theoretical calculations are performed on ammonium ion-water clusters. These theoretical calculations are focused on determining the following characteristics: (1) the pattern of cluster growth; (2) the percentages of clusters of the same size at different temperatures and humidities; (3) the distributions of different isomers for the same size clusters at different temperatures; (4) the relative strengths of the noncovalent interactions for clusters of different sizes. The results suggest that the dipole moment may be very significant for the ammonium ion-water system, and some new stable isomers were found. The nucleation of ammonium ions and water molecules is favorable at low temperatures; thus, the clusters observed at high altitudes might not be present at low altitudes. High humidity can contribute to the formation of large ammonium ion-water clusters, whereas the formation of small clusters may be favorable under low-humidity conditions. The potential energy surfaces (PES) of these different sized clusters are complicated and differ according to the distribution of isomers at different temperatures. Some similar structures are observed between NH4(+)(H2O)n and M(H2O)n (where M represents an alkali metal ion or water molecule); when n = 8, the clusters begin to form the closed-cage geometry. As the cluster size increases, these interactions become progressively weaker. The successive binding energy at the DF-MP2-F12/VDZ-F12 level is better than that at the PW91PW91/6-311++G(3df, 3pd) level and is consistent with the experimentally determined values.

Electron-induced hydrogen loss in uracil in a water cluster environment

International Nuclear Information System (INIS)

Smyth, M.; Kohanoff, J.; Fabrikant, I. I.

2014-01-01

Low-energy electron-impact hydrogen loss due to dissociative electron attachment (DEA) to the uracil and thymine molecules in a water cluster environment is investigated theoretically. Only the A ′ -resonance contribution, describing the near-threshold behavior of DEA, is incorporated. Calculations are based on the nonlocal complex potential theory and the multiple scattering theory, and are performed for a model target with basic properties of uracil and thymine, surrounded by five water molecules. The DEA cross section is strongly enhanced when the attaching molecule is embedded in a water cluster. This growth is due to two effects: the increase of the resonance lifetime and the negative shift in the resonance position due to interaction of the intermediate negative ion with the surrounding water molecules. A similar effect was earlier found in DEA to chlorofluorocarbons

Analyzing China Smart Water Meter Industry Cluster Competitiveness

OpenAIRE

Chan, Parker

2013-01-01

Sustainable development has always been a top issue nowadays. The smart water management is one of the methods to achieve the sustainable development. This paper aims to focus on analyzing the competitiveness of industrial clusters (Guangzhou, Ningbo and Shanghai) in China specifically to the smart water meter industry. It is part of the CEMIS sourcing work package under the KVTELIOS project with Mr. Al Natsheh Anas, and is supervised by Ms. Komulainen Ruey. Porter Diamond Theory is used ...

Fabrication of sub-micron whole waffer SIS tunnel junctions for millimeter wave mixers

International Nuclear Information System (INIS)

Huq, S.E.; Blamire, M.G.; Evetts, J.E.; Hasko, D.G.; Ahmed, H.

1991-01-01

As a part of a programme for the development of a space-qualified sub-mm-wave mixer operating in the region of one terahertz we have been developing the processes required for the fabrication of submicron whole wafer tunnel junctions. Using the self-aligned whole-wafer process (SAWW) with electron beam lithography we have been able to reliably fabricate high quality (V m > 20 mV) submicron tunnel junctions from whole wafer Nb/AlO x /Nb structures. In particular we show that the junction quality is independent of size down to 0.3 μm 2 junction area. The problems of film stress, anodization, registration for electron beam lithography and lift-off, which limit the yield of good quality sub-micron scale junctions are addressed in this paper

New Evidence of the Existence of Associative Elements of Water (Clusters)

OpenAIRE

Ignat Ignatov; Oleg Mosin

2016-01-01

In this review it is reported about new data on the structure of water cyclic associates (clusters) with general formula (Н2О)n and their charged ionic clusters [(Н2О)n]+ and [(Н2О)n]- by means of computer modelling and spectroscopy methods as 1Н-NMR, IR-spectroscopy, DNES, EXAFS-spectroscopy, X-Ray and neurons diffraction. The computer calculation of polyhedral nanoclusters (Н2О)n, where n = 3–20 are carried out. Based on this data the main structural mathematical models describing water str...

Water clustering on nanostructured iron oxide films

DEFF Research Database (Denmark)

Merte, Lindsay Richard; Bechstein, Ralf; Peng, G.

2014-01-01

, but it is not well-understood how these hydroxyl groups and their distribution on a surface affect the molecular-scale structure at the interface. Here we report a study of water clustering on a moire-structured iron oxide thin film with a controlled density of hydroxyl groups. While large amorphous monolayer...... islands form on the bare film, the hydroxylated iron oxide film acts as a hydrophilic nanotemplate, causing the formation of a regular array of ice-like hexameric nanoclusters. The formation of this ordered phase is localized at the nanometre scale; with increasing water coverage, ordered and amorphous...

A statistical analysis of North East Atlantic (submicron aerosol size distributions

Directory of Open Access Journals (Sweden)

M. Dall'Osto

2011-12-01

Full Text Available The Global Atmospheric Watch research station at Mace Head (Ireland offers the possibility to sample some of the cleanest air masses being imported into Europe as well as some of the most polluted being exported out of Europe. We present a statistical cluster analysis of the physical characteristics of aerosol size distributions in air ranging from the cleanest to the most polluted for the year 2008. Data coverage achieved was 75% throughout the year. By applying the Hartigan-Wong k-Means method, 12 clusters were identified as systematically occurring. These 12 clusters could be further combined into 4 categories with similar characteristics, namely: coastal nucleation category (occurring 21.3 % of the time, open ocean nucleation category (occurring 32.6% of the time, background clean marine category (occurring 26.1% of the time and anthropogenic category (occurring 20% of the time aerosol size distributions. The coastal nucleation category is characterised by a clear and dominant nucleation mode at sizes less than 10 nm while the open ocean nucleation category is characterised by a dominant Aitken mode between 15 nm and 50 nm. The background clean marine aerosol exhibited a clear bimodality in the sub-micron size distribution, with although it should be noted that either the Aitken mode or the accumulation mode may dominate the number concentration. However, peculiar background clean marine size distributions with coarser accumulation modes are also observed during winter months. By contrast, the continentally-influenced size distributions are generally more monomodal (accumulation, albeit with traces of bimodality. The open ocean category occurs more often during May, June and July, corresponding with the North East (NE Atlantic high biological period. Combined with the relatively high percentage frequency of occurrence (32.6%, this suggests that the marine biota is an important source of new nano aerosol particles in NE Atlantic Air.

Novel Translucent and Strong Submicron Alumina Ceramics for Dental Restorations.

Science.gov (United States)

Zhao, M; Sun, Y; Zhang, J; Zhang, Y

2018-03-01

An ideal ceramic restorative material should possess excellent aesthetic and mechanical properties. We hypothesize that the high translucency and strength of polycrystalline ceramics can be achieved through microstructural tailoring. The aim of this study is to demonstrate the superior optical and mechanical properties of a new class of submicron grain-sized alumina ceramics relative to the current state-of-the-art dental ceramic materials. The translucency, the in-line transmission ( T IT ) in particular, of these submicron alumina ceramics has been examined with the Rayleigh-Gans-Debye light-scattering model. The theoretical predictions related very well with the measured T IT values. The translucency parameter ( TP) and contrast ratio ( CR) of the newly developed aluminas were measured with a reflectance spectrophotometer on a black-and-white background. For comparison, the T IT , TP, and CR values for a variety of dental ceramics, mostly measured in-house but also cited from the literature, were included. The flexural strength of the aluminas was determined with the 4-point bending test. Our findings have shown that for polycrystalline alumina ceramics, an average grain size ceramic and zirconias, including the most translucent cubic-containing zirconias. The strength of these submicron grain-sized aluminas was significantly higher than that of the cubic-containing zirconia (e.g., Zpex Smile) and lithia-based glass-ceramics (e.g., IPS e.max CAD HT). A coarse-grained alumina could also reach a translucency level comparable to that of dental porcelain. However, the relatively low strength of this material has limited its clinical indications to structurally less demanding applications, such as orthodontic brackets. With a combined high strength and translucency, the newly developed submicron grain-sized alumina may be considered a suitable material for dental restorations.

Water Quality Evaluation of the Yellow River Basin Based on Gray Clustering Method

Science.gov (United States)

Fu, X. Q.; Zou, Z. H.

2018-03-01

Evaluating the water quality of 12 monitoring sections in the Yellow River Basin comprehensively by grey clustering method based on the water quality monitoring data from the Ministry of environmental protection of China in May 2016 and the environmental quality standard of surface water. The results can reflect the water quality of the Yellow River Basin objectively. Furthermore, the evaluation results are basically the same when compared with the fuzzy comprehensive evaluation method. The results also show that the overall water quality of the Yellow River Basin is good and coincident with the actual situation of the Yellow River basin. Overall, gray clustering method for water quality evaluation is reasonable and feasible and it is also convenient to calculate.

Laser plasmas as x-ray sources for lithographic imaging of submicron structures

International Nuclear Information System (INIS)

Bijkerk, F.; van Dorssen, G.E.; van der Wiel, M.J.

1988-01-01

Laser radiation can be used efficiently to generate x-rays for lithographic imaging of submicron patterns, e.g., for VLSI device fabrication. Due to their short wavelength and high average power, excimer lasers show much potential for this application. Results are presented of scaling studies for high repetition rate excimer laser application, using the frequency doubled output of a low repetition rate Nd:YAG/Glass laser. Spectral and spatial characteristics of x-ray emission of the laser plasma are shown. The power density in the laser focus was 3 x 10 12 W/cm 2 . With this source Si x-ray masks with submicron Au absorber profiles are imaged into high sensitivity x-ray photoresist. For the exposures 80 laser shots sufficed to yield high quality submicron structures. Extrapolation of the results to a high power excimer laser reduces the exposure time of the photoresists to several seconds, enabling a wafer throughput at an industrial level

A new route for the synthesis of submicron-sized LaB6

International Nuclear Information System (INIS)

Lihong, Bao; Wurentuya,; Wei, Wei; Tegus, O.

2014-01-01

Submicron crystalline LaB 6 has been successfully synthesized by a solid-state reaction of La 2 O 3 with NaBH 4 at 1200 °C. The effects of reaction temperature on the crystal structure, grain size and morphology were investigated by X-ray diffraction, scanning electron microscope and transmission electron microscope. It is found that when the reaction temperature is in the range of 1000–1100 °C, there are ultrafine nanoparticles and nanocrystals that coexist. When the reaction temperature elevated to 1200 °C, the grain morphology transformed from ultrafine nanoparticle to submicron crystals completely. High resolution transmission electron microscope images fully confirm the formation of LaB 6 cubic structure. - Highlights: • Single-phased LaB 6 have been synthesized by a solid-state reaction in a continuous evacuating process. • The reaction temperature has a important effect on the phase composition. • The grain size increase from nano-size to submicron with increasing reaction temperature

Manufacturing a submicron structure using a liquid precursor

NARCIS (Netherlands)

Ishihara, R.; Van de Zwan, M.; Trifunovic, M.

2014-01-01

Methods for manufacture of a submicron semiconductor structure on a substrate are described. The method may comprise: forming at least one template layer over a support substrate; forming one or more template structures, preferably one or more recesses and/or mesas, in said template layer, said one

Electron-induced hydrogen loss in uracil in a water cluster environment

Energy Technology Data Exchange (ETDEWEB)

Smyth, M.; Kohanoff, J. [Atomistic Simulation Centre, Queen' s University Belfast, Belfast BT7 1NN, Northern Ireland (United Kingdom); Fabrikant, I. I., E-mail: ifabrikant1@unl.edu [Department of Physics and Astronomy, University of Nebraska, Lincoln, Nebraska 68588, USA and Department of Physical Sciences, The Open University, Walton Hall, Milton Keynes MK7 6AA (United Kingdom)

2014-05-14

Low-energy electron-impact hydrogen loss due to dissociative electron attachment (DEA) to the uracil and thymine molecules in a water cluster environment is investigated theoretically. Only the A{sup ′}-resonance contribution, describing the near-threshold behavior of DEA, is incorporated. Calculations are based on the nonlocal complex potential theory and the multiple scattering theory, and are performed for a model target with basic properties of uracil and thymine, surrounded by five water molecules. The DEA cross section is strongly enhanced when the attaching molecule is embedded in a water cluster. This growth is due to two effects: the increase of the resonance lifetime and the negative shift in the resonance position due to interaction of the intermediate negative ion with the surrounding water molecules. A similar effect was earlier found in DEA to chlorofluorocarbons.

Preparation and optimization of submicron chitosan capsules by water-based electrospraying for food and bioactive packaging applications.

Science.gov (United States)

Sreekumar, Sruthi; Lemke, Philipp; Moerschbacher, Bruno M; Torres-Giner, Sergio; Lagaron, Jose M

2017-10-01

In the present study, a well-defined set of chitosans, with different degrees of acetylation (DA) and degrees of polymerization (DP), were processed by solution electrospraying from a water-based solvent. The solution properties, in terms of surface tension, conductivity, viscosity, and pH, were characterized and related to the physico-chemical properties of the chitosans. It was observed that both DA and DP values of a given chitosan, in combination with biopolymer concentration, mainly determined solution viscosity. This was, in turn, the major driving factor that defined the electrosprayability of chitosan. In addition, the physico-chemical properties of chitosans highly influenced solution conductivity and results indicated that the chitosan solutions with low or low-to-medium values of conductivity were the most optimal for electrospraying. The results obtained here also demonstrate that a good process control can be achieved by adjusting the working conditions, i.e. applied voltage, flow-rate, and tip-to-collector distance. Finally, it was also shown that electrosprayability of chitosan with inadequate physico-chemical properties can be improved by solution mixing of very different kinds of this polysaccharide. The resultant electrosprayed submicron chitosan capsules can be applied for encapsulation of food additives and to develop bioactive coatings of interest in food packaging, where these particles alone or containing functional ingredients can be released from the package into the food to promote a health benefit.

Mechanisms of Current Transfer in Electrodeposited Layers of Submicron Semiconductor Particles

Science.gov (United States)

Zhukov, N. D.; Mosiyash, D. S.; Sinev, I. V.; Khazanov, A. A.; Smirnov, A. V.; Lapshin, I. V.

2017-12-01

Current-voltage ( I- V) characteristics of conductance in multigrain layers of submicron particles of silicon, gallium arsenide, indium arsenide, and indium antimonide have been studied. Nanoparticles of all semiconductors were obtained by processing initial single crystals in a ball mill and applied after sedimentation onto substrates by means of electrodeposition. Detailed analysis of the I- V curves of electrodeposited layers shows that their behavior is determined by the mechanism of intergranular tunneling emission from near-surface electron states of submicron particles. Parameters of this emission process have been determined. The proposed multigrain semiconductor structures can be used in gas sensors, optical detectors, IR imagers, etc.

Decomposition of atmospheric water content into cluster contributions based on theoretical association equilibrium constants

International Nuclear Information System (INIS)

Slanina, Z.

1987-01-01

Water vapor is treated as an equilibrium mixture of water clusters (H 2 O)/sub i/ using quantum-chemical evaluation of the equilibrium constants of water associations. The model is adapted to the conditions of atmospheric humidity, and a decomposition algorithm is suggested using the temperature and mass concentration of water as input information and used for a demonstration of evaluation of the water oligomer populations in the Earth's atmosphere. An upper limit of the populations is set up based on the water content in saturated aqueous vapor. It is proved that the cluster population in the saturated water vapor, as well as in the Earth's atmosphere for a typical temperature/humidity profile, increases with increasing temperatures

Electric dipole moments of nanosolvated acid molecules in water clusters.

Science.gov (United States)

Guggemos, Nicholas; Slavíček, Petr; Kresin, Vitaly V

2015-01-30

The electric dipole moments of (H2O)nDCl (n=3-9) clusters have been measured by the beam-deflection method. Reflecting the (dynamical) charge distribution within the system, the dipole moment contributes information about the microscopic structure of nanoscale solvation. The addition of a DCl molecule to a water cluster results in a strongly enhanced susceptibility. There is evidence for a noticeable rise in the dipole moment occurring at n≈5-6. This size is consistent with predictions for the onset of ionic dissociation. Additionally, a molecular-dynamics model suggests that even with a nominally bound impurity an enhanced dipole moment can arise due to the thermal and zero-point motion of the proton and the water molecules. The experimental measurements and the calculations draw attention to the importance of fluctuations in defining the polarity of water-based nanoclusters and generally to the essential role played by motional effects in determining the response of fluxional nanoscale systems under realistic conditions.

Submicron Resolution Spectral-Domain Optical Coherence Tomography

KAUST Repository

Alarousu, Erkki

2013-11-14

Apparatuses and systems for submicron resolution spectral-domain optical coherence tomography (OCT) are disclosed. The system may use white light sources having wavelengths within 400-1000 nanometers, and achieve resolution below 1 .mu.m. The apparatus is aggregated into a unitary piece, and a user can connect the apparatus to a user provided controller and/or light source. The light source may be a supercontinuum source.

Zero point energy of polyhedral water clusters.

Science.gov (United States)

Anick, David J

2005-06-30

Polyhedral water clusters (PWCs) are cage-like (H2O)n clusters where every O participates in exactly three H bonds. For a database of 83 PWCs, 8 zero point energy (ZPE) was calculated at the B3LYP/6-311++G** level. ZPE correlates negatively with electronic energy (E0): each increase of 1 kcal/mol in E0 corresponds to a decrease of about 0.11 kcal/mol in ZPE. For each n, a set of four connectivity parameters accounts for 98% or more of the variance in ZPE. Linear regression of ZPE against n and this set gives an RMS error of 0.13 kcal/mol. The contributions to ZPE from stretch modes only (ZPE(S)) and from torsional modes only (ZPE(T)) also correlate strongly with E0 and with each other.

Dynamic lifetimes of cagelike water clusters immersed in liquid water and their implications for hydrate nucleation studies

Energy Technology Data Exchange (ETDEWEB)

Guo, G.J.; Zhang, Y.G.; Li, M.; Wu, C.H. [Chinese Academy of Sciences, Inst. of Geology and Geophysics, Beijing (China). Key Laboratory of the Study of Earth' s Deep Interior

2008-07-01

In hydrate research fields, the hydrate nucleation mechanism still remains as an unsolved question. The static lifetimes of cagelike water clusters (CLWC) immersed in bulk liquid water have recently been measured by performing molecular dynamics simulations in the methane-water system, during which the member-water molecules of CLWCs are not allowed to exchange with their surrounding water molecules. This paper presented a study that measured the dynamic lifetimes of CLWCs permitting such water exchanges. The study involved re-analysis of previous simulation data that were used to study the effect of methane adsorption on the static lifetimes of a dodecahedral water cluster (DWC). The dynamic lifetimes of the DWC were calculated. The results of lifetime measurements of DWC in different systems were provided. The implications of this study for hydrate nucleation were also discussed. It was found that the dynamic lifetimes of CLWCs were not less than the static lifetimes previously obtained, and their ratio increased with the lifetime values. The results strengthened that CLWCs are metastable structures in liquid water and the occurrence probability of long-lived CLWCs will increase if one uses the dynamic lifetimes instead of the static lifetimes. 13 refs., 1 tab., 3 figs.

Modeling and clustering water demand patterns from real-world smart meter data

Directory of Open Access Journals (Sweden)

N. Cheifetz

2017-08-01

Full Text Available Nowadays, drinking water utilities need an acute comprehension of the water demand on their distribution network, in order to efficiently operate the optimization of resources, manage billing and propose new customer services. With the emergence of smart grids, based on automated meter reading (AMR, a better understanding of the consumption modes is now accessible for smart cities with more granularities. In this context, this paper evaluates a novel methodology for identifying relevant usage profiles from the water consumption data produced by smart meters. The methodology is fully data-driven using the consumption time series which are seen as functions or curves observed with an hourly time step. First, a Fourier-based additive time series decomposition model is introduced to extract seasonal patterns from time series. These patterns are intended to represent the customer habits in terms of water consumption. Two functional clustering approaches are then used to classify the extracted seasonal patterns: the functional version of K-means, and the Fourier REgression Mixture (FReMix model. The K-means approach produces a hard segmentation and K representative prototypes. On the other hand, the FReMix is a generative model and also produces K profiles as well as a soft segmentation based on the posterior probabilities. The proposed approach is applied to a smart grid deployed on the largest water distribution network (WDN in France. The two clustering strategies are evaluated and compared. Finally, a realistic interpretation of the consumption habits is given for each cluster. The extensive experiments and the qualitative interpretation of the resulting clusters allow one to highlight the effectiveness of the proposed methodology.

Modeling and clustering water demand patterns from real-world smart meter data

Science.gov (United States)

Cheifetz, Nicolas; Noumir, Zineb; Samé, Allou; Sandraz, Anne-Claire; Féliers, Cédric; Heim, Véronique

2017-08-01

Nowadays, drinking water utilities need an acute comprehension of the water demand on their distribution network, in order to efficiently operate the optimization of resources, manage billing and propose new customer services. With the emergence of smart grids, based on automated meter reading (AMR), a better understanding of the consumption modes is now accessible for smart cities with more granularities. In this context, this paper evaluates a novel methodology for identifying relevant usage profiles from the water consumption data produced by smart meters. The methodology is fully data-driven using the consumption time series which are seen as functions or curves observed with an hourly time step. First, a Fourier-based additive time series decomposition model is introduced to extract seasonal patterns from time series. These patterns are intended to represent the customer habits in terms of water consumption. Two functional clustering approaches are then used to classify the extracted seasonal patterns: the functional version of K-means, and the Fourier REgression Mixture (FReMix) model. The K-means approach produces a hard segmentation and K representative prototypes. On the other hand, the FReMix is a generative model and also produces K profiles as well as a soft segmentation based on the posterior probabilities. The proposed approach is applied to a smart grid deployed on the largest water distribution network (WDN) in France. The two clustering strategies are evaluated and compared. Finally, a realistic interpretation of the consumption habits is given for each cluster. The extensive experiments and the qualitative interpretation of the resulting clusters allow one to highlight the effectiveness of the proposed methodology.

Submicron particle monitoring of paving and related road construction operations.

Science.gov (United States)

Freund, Alice; Zuckerman, Norman; Baum, Lisa; Milek, Debra

2012-01-01

This study identified activities and sources that contribute to ultrafine and other submicron particle exposure that could trigger respiratory symptoms in highway repair workers. Submicron particle monitoring was conducted for paving, milling, and pothole repair operations in a major metropolitan area where several highway repair workers were identified as symptomatic for respiratory illness following exposures at the 2001 World Trade Center disaster site. Exposure assessments were conducted for eight trades involved in road construction using a TSI P-Trak portable condensation particle counter. Direct readings near the workers' breathing zones and observations of activities and potential sources were logged on 7 days on 27 workers using four different models of pavers and two types of millers. Average worker exposure levels ranged from 2 to 3 times background during paving and from 1 to 4 times background during milling. During asphalt paving, average personal exposures to submicron particulates were 25,000-60,000, 28,000-70,000, and 23,000-37,000 particles/ cm(3) for paver operators, screed operators, and rakers, respectively. Average personal exposures during milling were 19,000-111,000, 28,000-81,000, and 19,000 particles/cm(3) for the large miller operators, miller screed operators, and raker, respectively. Personal peak exposures were measured up to 467,000 and 455,000 particles/cm(3) in paving and milling, respectively. Several sources of submicron particles were identified. These included the diesel and electric fired screed heaters; engine exhaust from diesel powered construction vehicles passing by or idling; raking, dumping, and paving of asphalt; exhaust from the hotbox heater; pavement dust or fumes from milling operations, especially when the large miller started and stopped; and secondhand cigarette smoke. To reduce the potential for health effects in workers, over 40 recommendations were made to control exposures, including improved maintenance of

Thermophoretic motion behavior of submicron particles in boundary-layer-separation flow around a droplet.

Science.gov (United States)

Wang, Ao; Song, Qiang; Ji, Bingqiang; Yao, Qiang

2015-12-01

As a key mechanism of submicron particle capture in wet deposition and wet scrubbing processes, thermophoresis is influenced by the flow and temperature fields. Three-dimensional direct numerical simulations were conducted to quantify the characteristics of the flow and temperature fields around a droplet at three droplet Reynolds numbers (Re) that correspond to three typical boundary-layer-separation flows (steady axisymmetric, steady plane-symmetric, and unsteady plane-symmetric flows). The thermophoretic motion of submicron particles was simulated in these cases. Numerical results show that the motion of submicron particles around the droplet and the deposition distribution exhibit different characteristics under three typical flow forms. The motion patterns of particles are dependent on their initial positions in the upstream and flow forms. The patterns of particle motion and deposition are diversified as Re increases. The particle motion pattern, initial position of captured particles, and capture efficiency change periodically, especially during periodic vortex shedding. The key effects of flow forms on particle motion are the shape and stability of the wake behind the droplet. The drag force of fluid and the thermophoretic force in the wake contribute jointly to the deposition of submicron particles after the boundary-layer separation around a droplet.

Magnetoresistance and magnetization in submicron ferromagnetic gratings

Science.gov (United States)

Shearwood, C.; Blundell, S. J.; Baird, M. J.; Bland, J. A. C.; Gester, M.; Ahmed, H.; Hughes, H. P.

1994-05-01

A technique for engineering micron and submicron scale structures from magnetic films of transition metals has been developed using a combination of electron- and ion-beam lithography enabling high-quality arrays of submicron magnetic Fe wires to be fabricated. This process can be used to fabricate novel devices from a variety of metal combinations which would not be possible by the usual liftoff metallization method. The structure and magnetic properties are reported of an epitaxial 25 nm Fe(001)/GaAs(001) film and the wire gratings which are fabricated from it. The width of the wires in the grating is 0.5 μm for all structures studied, but the separation of each wire is varied in the range 0.5 to 16 μm. An artificially induced shape anisotropy field of around 1 kG, consistent with a magnetostatic calculation, was observed for all separations studied. The field dependence of the magneto-optic Kerr effect and magnetoresistance (MR) data is consistent with a twisted magnetization configuration across the width of the sample beneath saturation for transverse applied fields. In this case, the detailed form of the field dependence of the MR is strikingly modified from that observed in the continuous film and is consistent with coherent rotation of the magnetization.

Electron scattering in large water clusters from photoelectron imaging with high harmonic radiation.

Science.gov (United States)

Gartmann, Thomas E; Hartweg, Sebastian; Ban, Loren; Chasovskikh, Egor; Yoder, Bruce L; Signorell, Ruth

2018-06-06

Low-energy electron scattering in water clusters (H2O)n with average cluster sizes of n < 700 is investigated by angle-resolved photoelectron spectroscopy using high harmonic radiation at photon energies of 14.0, 20.3, and 26.5 eV for ionization from the three outermost valence orbitals. The measurements probe the evolution of the photoelectron anisotropy parameter β as a function of cluster size. A remarkably steep decrease of β with increasing cluster size is observed, which for the largest clusters reaches liquid bulk values. Detailed electron scattering calculations reveal that neither gas nor condensed phase scattering can explain the cluster data. Qualitative agreement between experiment and simulations is obtained with scattering calculations that treat cluster scattering as an intermediate case between gas and condensed phase scattering.

Sub-micron indent induced plastic deformation in copper and irradiated steel

International Nuclear Information System (INIS)

Robertson, Ch.

1998-09-01

In this work we aim to study the indent induced plastic deformation. For this purpose, we have developed a new approach, whereby the indentation curves provides the mechanical behaviour, while the deformation mechanisms are observed thanks to Transmission Electron Microscopy (TEM). In order to better understand how an indent induced dislocation microstructure forms, numerical modeling of the indentation process at the scale of discrete dislocations has been worked out as well. Validation of this modeling has been performed through direct comparison of the computed microstructures with TEM micrographs of actual indents in pure Cu [001]. Irradiation induced modifications of mechanical behaviour of ion irradiated 316L have been investigated, thanks to the mentioned approach. An important hardening effect was reported from indentation data (about 50%), on helium irradiated 316L steel. TEM observations of the damage zone clearly show that this behaviour is associated with the presence of He bubbles. TEM observations of the indent induced plastic zone also showed that the extent of the plastic zone is strongly correlated with hardness, that is to say: harder materials gets a smaller plastic zone. These results thus clearly established that the selected procedure can reveal any irradiation induced hardening in sub-micron thick ion irradiated layers. The behaviour of krypton irradiated 316L steel is somewhat more puzzling. In one hand indeed, a strong correlation between the defect cluster size and densities on the irradiation temperature is observed in the 350 deg C -600 deg C range, thanks to TEM observations of the damage zone. On the other hand, irradiation induced hardening reported from indentation data is relatively small (about 10%) and shows no dependence upon the irradiation temperature (within the mentioned range). In addition, it has been shown that the reported hardening vanishes following appropriate post-irradiation annealing, although most of the TEM

Influence of locational states of submicron fibers added into matrix on mechanical properties of plain-woven Carbon Fiber Composite

Directory of Open Access Journals (Sweden)

Kumamoto Soichiro

2016-01-01

Full Text Available The aim of this study was to show the influence of locational states of submicron fibers added into epoxy matrix on mechanical properties of modified plane-woven carbon fiber reinforced plastic (CFRP. To change the locational states of submicron fibers, two kinds of fabrication processes were applied in preparing specimen by hand lay-up method. Submicron fibers were simply added into epoxy resin with ethanol after they were stirred by a dispersion process using homogenizer to be located far from the interface between reinforcement and matrix. In contrast, submicron fibers were attached onto the carbon fibers by injecting from a spray nozzle accompanying with ethanol to be located near the interface, after they were tentatively contained in ethanol. The plain-woven CFRP plates were fabricated by hand lay-up method and cured at 80 degree-C for 1 hour and then at 150 degree-C for 3 hours. After curing, the plain-woven CFRP plates were cut into the dimension of specimen. Tensile shear strength and Mode-II fracture toughness of CFRP were determined by tensile lap-shear test and End-notched flexure(ENF test, respectively. When submicron fibers were located far from the interface between carbon fibers and epoxy resin, tensile shear strength and Mode-II fracture toughness of CFRP were improved 30% and 18% compared with those of unmodified case. The improvement ratio in modified case was rather low (about few percentages in the case where submicron fibers were located near the interface. The result suggested that crack propagation should be prevented when submicron fibers were existed far from the interface due to the effective stress state around the crack tip.

Degradation of CMOS image sensors in deep-submicron technology due to γ-irradiation

Science.gov (United States)

Rao, Padmakumar R.; Wang, Xinyang; Theuwissen, Albert J. P.

2008-09-01

In this work, radiation induced damage mechanisms in deep submicron technology is resolved using finger gated-diodes (FGDs) as a radiation sensitive tool. It is found that these structures are simple yet efficient structures to resolve radiation induced damage in advanced CMOS processes. The degradation of the CMOS image sensors in deep-submicron technology due to γ-ray irradiation is studied by developing a model for the spectral response of the sensor and also by the dark-signal degradation as a function of STI (shallow-trench isolation) parameters. It is found that threshold shifts in the gate-oxide/silicon interface as well as minority carrier life-time variations in the silicon bulk are minimal. The top-layer material properties and the photodiode Si-SiO2 interface quality are degraded due to γ-ray irradiation. Results further suggest that p-well passivated structures are inevitable for radiation-hard designs. It was found that high electrical fields in submicron technologies pose a threat to high quality imaging in harsh environments.

[Nasal submicron emulsion of Scutellariae Radix extract preparation technology research based on phase transfer of solute technology].

Science.gov (United States)

Shi, Ya-jun; Shi, Jun-hui; Chen, Shi-bin; Yang, Ming

2015-07-01

Based on the demand of nasal drug delivery high drug loadings, using the unique phase transfer of solute, integrating the phospholipid complex preparation and submicron emulsion molding process of Scutellariae Radix extract, the study obtained the preparation of the high drug loadings submicron emulsion of Scutellariae Radix extract. In the study of drug solution dispersion method, the uniformity of drug dispersed as the evaluation index, the traditional mixing method, grinding, homogenate and solute phase transfer technology were investigated, and the solute phase transfer technology was adopted in the last. With the adoption of new technology, the drug loading capacity reached 1.33% (phospholipid complex was 4%). The drug loading capacity was improved significantly. The transfer of solute method and timing were studied as follows,join the oil phase when the volume of phospholipid complex anhydrous ethanol solution remaining 30%, the solute phase transfer was completed with the continued recycling of anhydrous ethanol. After drug dissolved away to oil phase, the preparation technology of colostrum was determined with the evaluation index of emulsion droplet form. The particle size of submicron emulsion, PDI and stability parameters were used as evaluation index, orthogonal methodology were adopted to optimize the submicron emulsion ingredient and main influential factors of high pressure homogenization technology. The optimized preparation technology of Scutellariae Radix extract nasal submicron emulsion is practical and stable.

Hot carrier degradation and a new lifetime prediction model in ultra-deep sub-micron pMOSFET

International Nuclear Information System (INIS)

Lei Xiao-Yi; Liu Hong-Xia; Zhang Kai; Zhang Yue; Zheng Xue-Feng; Ma Xiao-Hua; Hao Yue

2013-01-01

The hot carrier effect (HCE) of an ultra-deep sub-micron p-channel metal—oxide semiconductor field-effect transistor (pMOSFET) is investigated in this paper. Experiments indicate that the generation of positively charged interface states is the predominant mechanism in the case of the ultra-deep sub-micron pMOSFET. The relation of the pMOSFET hot carrier degradation to stress time (t), channel width (W), channel length (L), and stress voltage (V d ) is then discussed. Based on the relation, a lifetime prediction model is proposed, which can predict the lifetime of the ultra-deep sub-micron pMOSFET accurately and reflect the influence of the factors on hot carrier degradation directly. (condensed matter: electronic structure, electrical, magnetic, and optical properties)

Influence of PEG Stoichiometry on Structure-Tuned Formation of Self-Assembled Submicron Nickel Particles

Directory of Open Access Journals (Sweden)

Bingxue Pu

2018-01-01

Full Text Available Self-assembled submicron nickel particles were successfully synthesized via the one-step surfactant-assisted solvothermal method. The impact of surfactant and reducing agent stoichiometry is investigated in this manuscript. Different morphologies and structures of Ni particles, including flower-like nanoflakes, hydrangea-like structures, chain structures, sphere-like structures, and hollow structures were prepared through different processing conditions with two parameters such as temperature and time. Based on scanning electron microscopy (SEM, X-ray diffraction (XRD, thermal gravimetric analysis (TGA and vibrating sample magnetometry (VSM, the submicron nickel particles show good saturation magnetization and excellent thermal stabilities with a possible growth mechanism for the variety of the structure-tuned formation. Importantly, the microwave absorption properties of the submicron nickel particles were studied. The lowest reflection loss of Ni-P9/T200/H15 with a thin layer thickness of 1.7 mm can reach −42.6 dB at 17.3 GHz.

Pattern imprinting in deep sub-micron static random access memories induced by total dose irradiation

Science.gov (United States)

Zheng, Qi-Wen; Yu, Xue-Feng; Cui, Jiang-Wei; Guo, Qi; Ren, Di-Yuan; Cong, Zhong-Chao; Zhou, Hang

2014-10-01

Pattern imprinting in deep sub-micron static random access memories (SRAMs) during total dose irradiation is investigated in detail. As the dose accumulates, the data pattern of memory cells loading during irradiation is gradually imprinted on their background data pattern. We build a relationship between the memory cell's static noise margin (SNM) and the background data, and study the influence of irradiation on the probability density function of ΔSNM, which is the difference between two data sides' SNMs, to discuss the reason for pattern imprinting. Finally, we demonstrate that, for micron and deep sub-micron devices, the mechanism of pattern imprinting is the bias-dependent threshold shift of the transistor, but for a deep sub-micron device the shift results from charge trapping in the shallow trench isolation (STI) oxide rather than from the gate oxide of the micron-device.

Water droplet excess free energy determined by cluster mitosis using guided molecular dynamics

Science.gov (United States)

Lau, Gabriel V.; Hunt, Patricia A.; Müller, Erich A.; Jackson, George; Ford, Ian J.

2015-12-01

Atmospheric aerosols play a vital role in affecting climate by influencing the properties and lifetimes of clouds and precipitation. Understanding the underlying microscopic mechanisms involved in the nucleation of aerosol droplets from the vapour phase is therefore of great interest. One key thermodynamic quantity in nucleation is the excess free energy of cluster formation relative to that of the saturated vapour. In our current study, the excess free energy is extracted for clusters of pure water modelled with the TIP4P/2005 intermolecular potential using a method based on nonequilibrium molecular dynamics and the Jarzynski relation. The change in free energy associated with the "mitosis" or division of a cluster of N water molecules into two N/2 sub-clusters is evaluated. This methodology is an extension of the disassembly procedure used recently to calculate the excess free energy of argon clusters [H. Y. Tang and I. J. Ford, Phys. Rev. E 91, 023308 (2015)]. Our findings are compared to the corresponding excess free energies obtained from classical nucleation theory (CNT) as well as internally consistent classical theory (ICCT). The values of the excess free energy that we obtain with the mitosis method are consistent with CNT for large cluster sizes but for the smallest clusters, the results tend towards ICCT; for intermediate sized clusters, we obtain values between the ICCT and CNT predictions. Furthermore, the curvature-dependent surface tension which can be obtained by regarding the clusters as spherical droplets of bulk density is found to be a monotonically increasing function of cluster size for the studied range. The data are compared to other values reported in the literature, agreeing qualitatively with some but disagreeing with the values determined by Joswiak et al. [J. Phys. Chem. Lett. 4, 4267 (2013)] using a biased mitosis approach; an assessment of the differences is the main motivation for our current study.

Water droplet excess free energy determined by cluster mitosis using guided molecular dynamics

Energy Technology Data Exchange (ETDEWEB)

Lau, Gabriel V.; Müller, Erich A.; Jackson, George [Department of Chemical Engineering, Imperial College London, South Kensington Campus, London SW7 2AZ (United Kingdom); Hunt, Patricia A. [Department of Chemistry, Imperial College London, South Kensington Campus, London SW7 2AZ (United Kingdom); Ford, Ian J. [Department of Physics and Astronomy and London Centre for Nanotechnology, University College London, Gower Street, London WC1E 6BT (United Kingdom)

2015-12-28

Atmospheric aerosols play a vital role in affecting climate by influencing the properties and lifetimes of clouds and precipitation. Understanding the underlying microscopic mechanisms involved in the nucleation of aerosol droplets from the vapour phase is therefore of great interest. One key thermodynamic quantity in nucleation is the excess free energy of cluster formation relative to that of the saturated vapour. In our current study, the excess free energy is extracted for clusters of pure water modelled with the TIP4P/2005 intermolecular potential using a method based on nonequilibrium molecular dynamics and the Jarzynski relation. The change in free energy associated with the “mitosis” or division of a cluster of N water molecules into two N/2 sub-clusters is evaluated. This methodology is an extension of the disassembly procedure used recently to calculate the excess free energy of argon clusters [H. Y. Tang and I. J. Ford, Phys. Rev. E 91, 023308 (2015)]. Our findings are compared to the corresponding excess free energies obtained from classical nucleation theory (CNT) as well as internally consistent classical theory (ICCT). The values of the excess free energy that we obtain with the mitosis method are consistent with CNT for large cluster sizes but for the smallest clusters, the results tend towards ICCT; for intermediate sized clusters, we obtain values between the ICCT and CNT predictions. Furthermore, the curvature-dependent surface tension which can be obtained by regarding the clusters as spherical droplets of bulk density is found to be a monotonically increasing function of cluster size for the studied range. The data are compared to other values reported in the literature, agreeing qualitatively with some but disagreeing with the values determined by Joswiak et al. [J. Phys. Chem. Lett. 4, 4267 (2013)] using a biased mitosis approach; an assessment of the differences is the main motivation for our current study.

Proceedings of submicron multiphase materials

International Nuclear Information System (INIS)

Baney, R.; Gilliom, L.; Hirano, S.I.; Schmidt, H.

1992-01-01

This book contains the papers presented at Symposium R of the spring 1992 Materials Research Society meeting held in San Francisco, California. The title of the symposium, Submicron Multiphase Materials, was selected by the organizers to encompass the realm of composite materials from those smaller than conventional fiber matrix composites to those with phase separation dimensions approaching molecular dimensions. The development of composite materials is as old as the development of materials. Humans quickly learned that, by combining materials, the best properties of each can be realized and that, in fact, synergistic effects often arise. For example, chopped straw was used by the Israelites to limit cracking in bricks. The famed Japanese samurai swords were multilayers of hard oxide and tough ductile materials. One also finds in nature examples of composite materials. These range form bone to wood, consisting of a hard phase which provides strength and stiffness and a softer phase for toughness. Advanced composites are generally thought of as those which are based on a high modulus, discontinuous, chopped or woven fiber phase and a continuous polymer phase. In multiphase composites, dimensions can range from meters in materials such as steel rod-reinforced concrete structures to angstroms. In macrophase separated composite materials, properties frequently follow the rule of mixtures with the properties approximating the arithmetic mean of the properties of each individual phase, if there is good coupling between the phases. As the phases become smaller, the surface to volume ratio grows in importance with respect to properties. Interfacial and interphase phenomena being to dominate. Surface free energies play an ever increasing role in controlling properties. In recent years, much research in materials science has been directed at multiphase systems where phase separations are submicron in at least some dimension

Which Density Functional Should Be Used to Describe Protonated Water Clusters?

Science.gov (United States)

Shi, Ruili; Huang, Xiaoming; Su, Yan; Lu, Hai-Gang; Li, Si-Dian; Tang, Lingli; Zhao, Jijun

2017-04-27

Protonated water cluster is one of the most important hydrogen-bond network systems. Finding an appropriate DFT method to study the properties of protonated water clusters can substantially improve the economy in computational resources without sacrificing the accuracy compared to high-level methods. Using high-level MP2 and CCSD(T) methods as well as experimental results as benchmark, we systematically examined the effect of seven exchange-correlation GGA functionals (with BLYP, B3LYP, X3LYP, PBE0, PBE1W, M05-2X, and B97-D parametrizations) in describing the geometric parameters, interaction energies, dipole moments, and vibrational properties of protonated water clusters H + (H 2 O) 2-9,12 . The overall performance of all these functionals is acceptable, and each of them has its advantage in certain aspects. X3LYP is the best to describe the interaction energies, and PBE0 and M05-2X are also recommended to investigate interaction energies. PBE0 gives the best anharmonic frequencies, followed by PBE1W, B97-D and BLYP methods. PBE1W, B3LYP, B97-D, and X3LYP can yield better geometries. The capability of B97-D to distinguish the relative energies between isomers is the best among all the seven methods, followed by M05-2X and PBE0.

Effects of clustering structure on volumetric properties of amino acids in (DMSO + water) mixtures

International Nuclear Information System (INIS)

Huang Aimin; Liu Chunli; Ma Lin; Tong Zhangfa; Lin Ruisen

2012-01-01

Graphical abstract: Together with static light scattering measurement, volumetric properties of glycine, L-alanine and L-serine were determined and utilized to reveal the microscopic solvent structure of (DMSO + water) mixtures and its influence on the interaction between DMSO and amino acids from a clustering point of view. The results demonstrated that the interaction between amino acids and DMSO was greatly related to the clustering structure of the mixed solvent and that amino acids interacted with already established solvent clusters. Hydrophobic aggregating of DMSO lead to a decrease in the hydrophobic effect of DMSO and the hydrophobic–hydrophilic and hydrophobic–hydrophobic interaction with amino acids, which was reflected by the solvation of proteins. Highlights: ► Determine volumetric properties of three amino acids in aqueous DMSO in details. ► Static light scattering measurement for clustering structure of aqueous DMSO. ► Volumetric behaviour of amino acids depends on clustering structure of aqueous DMSO. ► Clustering structure of aqueous DMSO influences solvation of protein and cellulose. - Abstract: For a better understanding on the functions of DMSO in biological systems at a relatively lower concentration, apparent molar volumes of three typical amino acids, glycine, L-alanine and L-serine in (DMSO + water) mixtures were determined and the transfer volumes from water to the mixtures were evaluated. Together with static light scattering measurement, the results were utilised to reveal the microscopic solvent structure of (DMSO + water) mixtures and its influence on the interaction between DMSO and amino acids from a clustering point of view. The results demonstrate that the interaction between amino acids and DMSO is greatly related to the clustering structure of the mixed solvent and that amino acids interacted with already established solvent clusters. The linear dependence of transfer volume of amino acids on DMSO concentration up to 2

DMSO-Water Clustering in Solution Observed in Soft X-ray Spectra.

Science.gov (United States)

Engel, Nicholas; Atak, Kaan; Lange, Kathrin M; Gotz, Malte; Soldatov, Mikhail; Golnak, Ronny; Suljoti, Edlira; Rubensson, Jan-Erik; Aziz, Emad F

2012-12-20

The significant deviation from the ideality of dimethyl sulfoxide (DMSO)/water mixtures can be addressed based on the change of the local molecular orbitals of each solvent upon mixing. Oxygen K-edge absorption and emission spectra of DMSO/water solutions were measured using the liquid microjet technique. The spectra demonstrate that the hydrogen bond network in liquid water is already influenced at small DMSO concentrations, and at the molar fraction xDMSO = 0.43 we find strong evidence of DMSO-water clustering reflected by the influence on the occupied molecular orbitals.

Preparation of 1-pyrenebutyric acid and pyrene submicron dots by laser-induced molecular micro-jet implantation

International Nuclear Information System (INIS)

Pihosh, Y.; Goto, M.; Kasahara, A.; Tosa, M.

2009-01-01

Pyrene and 1-pyrenebuturic acid molecules were deposited on glass and copper substrates with the formation of submicron dots by laser-induced molecular micro-jet implantation through polar and non-polar liquid layers. The size of the smallest 1-pyrenebuturic acid molecules dots prepared on a glass substrate by implantation through water and diiodomethane was estimated to be about 400 nm and 300 nm at laser fluences of 235 J/cm 2 and 326 J/cm 2 , respectively. The fluorescence and the Raman spectra showed that the implanted 1-pyrenebutyric acid molecules did not decompose during the implantation process. The smallest size of a pyrene dot was 700 nm at the laser fluence of 378 J/cm 2 . However, the pyrene dots could be formed only by implantation through a water layer.

Energetics and dynamics of the neutralization of clustered ions in ammonia and water vapour

International Nuclear Information System (INIS)

Sennhauser, E.S.; Armstrong, D.A.

1978-01-01

The energetics and dynamics of neutralization reactions of clustered ions in ammonia and water vapour have been analysed. Neutralization rate coefficients were calculated for the ions in ammonia and for H + .(H 2 O)sub(n) combining with various clustered anions in water vapour up to densities of 4 x 10 19 molecule cm -3 at 390 K. In the case of ammonia, calculations were also performed at 298 K. For all systems, fractional contributions of the neutralization coefficients for specific cluster sizes to the overall coefficient αsub(eff) were evaluated. The computed value of αsub(eff) for NH 3 was in reasonable agreement with experimental data in the [NH 3 ] range 0.3 to 4 x 10 19 molecule cm -3 , and general trends stemming from the effects of increasing ion mass were pointed out. Calculations of energies of individual cluster sizes indicate possible neutralization reaction mechanisms. With some exception, proton transfer is the only possible path and no H atoms should be formed. This is in general agreement with literature results for water vapour at approximately 390 K and with [H 2 O] >= 2 x 10 x 10 19 molecule cm -3 . (author)

Electron driven water formation from oxyhydrogen clusters in superfluid helium nanodroplets

International Nuclear Information System (INIS)

Renzler, Michael; Kranabetter, Lorenz; Barwa, Erik; Scheier, Paul; Illenberger, Eugen

2015-01-01

Helium nanodroplets provide an enviroment that allow studies of chemical reactions at ultracold temperatures. We use these droplets as a matrix to study the formation of water upon electron bombardment of oxyhydrogen clusters (paper)

Pattern imprinting in deep sub-micron static random access memories induced by total dose irradiation

International Nuclear Information System (INIS)

Zheng Qi-Wen; Yu Xue-Feng; Cui Jiang-Wei; Guo Qi; Ren Di-Yuan; Cong Zhong-Chao; Zhou Hang

2014-01-01

Pattern imprinting in deep sub-micron static random access memories (SRAMs) during total dose irradiation is investigated in detail. As the dose accumulates, the data pattern of memory cells loading during irradiation is gradually imprinted on their background data pattern. We build a relationship between the memory cell's static noise margin (SNM) and the background data, and study the influence of irradiation on the probability density function of ΔSNM, which is the difference between two data sides' SNMs, to discuss the reason for pattern imprinting. Finally, we demonstrate that, for micron and deep sub-micron devices, the mechanism of pattern imprinting is the bias-dependent threshold shift of the transistor, but for a deep sub-micron device the shift results from charge trapping in the shallow trench isolation (STI) oxide rather than from the gate oxide of the micron-device. (condensed matter: structural, mechanical, and thermal properties)

A comparative ab initio study of Br2*- and Br2 water clusters.

Science.gov (United States)

Pathak, A K; Mukherjee, T; Maity, D K

2006-01-14

The work presents ab initio results on structure and electronic properties of Br2*-.nH2O(n=1-10) and Br2.nH2O(n=1-8) hydrated clusters to study the effects of an excess electron on the microhydration of the halide dimer. A nonlocal density functional, namely, Becke's half-and-half hybrid exchange-correlation functional is found to perform well on the present systems with a split valence 6-31++G(d,p) basis function. Geometry optimizations for all the clusters are carried out with several initial guess structures and without imposing any symmetry restriction. Br2*-.nH2O clusters prefer to have symmetrical double hydrogen-bonding structures. Results on Br2.nH2O(n>or=2) cluster show that the O atom of one H2O is oriented towards one Br atom and the H atom of another H2O is directed to other Br atom making Br2 to exist as Br+-Br- entity in the cluster. The binding and solvation energies are calculated for the Br2*-.nH2O and Br2.nH2O clusters. Calculations of the vibrational frequencies show that the formation of Br2*- and Br2 water clusters induces significant shifts from the normal modes of isolated water. Excited-state calculations are carried out on Br2*-.nH2O clusters following configuration interaction with single electron excitation procedure and UV-VIS absorption profiles are simulated. There is an excellent agreement between the present theoretical UV-VIS spectra of Br2*-.10H2O cluster and the reported transient optical spectra for Br2*- in aqueous solution.

Hot-carrier effects on irradiated deep submicron NMOSFET

International Nuclear Information System (INIS)

Cui Jiangwei; Zheng Qiwen; Yu Xuefeng; Cong Zhongchao; Zhou Hang; Guo Qi; Wen Lin; Wei Ying; Ren Diyuan

2014-01-01

We investigate how γ exposure impacts the hot-carrier degradation in deep submicron NMOSFET with different technologies and device geometries for the first time. The results show that hot-carrier degradations on irradiated devices are greater than those without irradiation, especially for narrow channel device. The reason is attributed to charge traps in STI, which then induce different electric field and impact ionization rates during hot-carrier stress. (semiconductor devices)

Effect of Water Clustering on the Activity of Candida antarctica Lipase B in Organic Medium

Directory of Open Access Journals (Sweden)

Sindrila Dutta Banik

2017-07-01

Full Text Available The effect of initial water activity of MTBE (methyl tert-butyl ether medium on CALB (Candida antarctica lipase B catalyzed esterification reaction is investigated using experimental methods and classical molecular dynamics (MD simulations. The experimental kinetic studies show that the initial reaction rate of CALB-catalyzed esterification reaction between butyric acid and ethanol decreases with increasing initial water activity of the medium. The highest rate of esterification is observed at the lowest water activity studied. MD simulations were performed to gain a molecular insight on the effect of initial water activity on the rate of CALB-catalyzed reaction. Our results show that hydration has an insignificant effect on the structure and flexibility of CALB. Rather, it appears that water molecules bind to certain regions (“hot spots” on the CALB surface and form clusters. The size of the water clusters at these hot spot regions gradually increase and expand with increasing water activity. Consequently, the surface area of CALB covered by the water molecules also increases. Specifically, our results indicate that a particular water cluster located close to the active site partially cover the binding pocket of substrate at high water activity. As a consequence, the effective concentration of substrate at the catalytic site decreases. Therefore, the reaction rate slows down with increasing water activity, which correlates well with the observed decrease in the experimentally determined initial reaction rate.

Assessment of Sub-Micron Particles by Exploiting Charge Differences with Dielectrophoresis

Directory of Open Access Journals (Sweden)

Maria F. Romero-Creel

2017-08-01

Full Text Available The analysis, separation, and enrichment of submicron particles are critical steps in many applications, ranging from bio-sensing to disease diagnostics. Microfluidic electrokinetic techniques, such as dielectrophoresis (DEP have proved to be excellent platforms for assessment of submicron particles. DEP is the motion of polarizable particles under the presence of a non-uniform electric field. In this work, the polarization and dielectrophoretic behavior of polystyrene particles with diameters ranging for 100 nm to 1 μm were studied employing microchannels for insulator based DEP (iDEP and low frequency (<1000 Hz AC and DC electric potentials. In particular, the effects of particle surface charge, in terms of magnitude and type of functionalization, were examined. It was found that the magnitude of particle surface charge has a significant impact on the polarization and dielectrophoretic response of the particles, allowing for successful particle assessment. Traditionally, charge differences are exploited employing electrophoretic techniques and particle separation is achieved by differential migration. The present study demonstrates that differences in the particle’s surface charge can also be exploited by means of iDEP; and that distinct types of nanoparticles can be identified by their polarization and dielectrophoretic behavior. These findings open the possibility for iDEP to be employed as a technique for the analysis of submicron biological particles, where subtle differences in surface charge could allow for rapid particle identification and separation.

A Facile Method for Separating and Enriching Nano and Submicron Particles from Titanium Dioxide Found in Food and Pharmaceutical Products

Science.gov (United States)

Yang, Yu; Capco, David G.; Westerhoff, Paul

2016-01-01

Recent studies indicate the presence of nano-scale titanium dioxide (TiO2) as an additive in human foodstuffs, but a practical protocol to isolate and separate nano-fractions from soluble foodstuffs as a source of material remains elusive. As such, we developed a method for separating the nano and submicron fractions found in commercial-grade TiO2 (E171) and E171 extracted from soluble foodstuffs and pharmaceutical products (e.g., chewing gum, pain reliever, and allergy medicine). Primary particle analysis of commercial-grade E171 indicated that 54% of particles were nano-sized (i.e., < 100 nm). Isolation and primary particle analysis of five consumer goods intended to be ingested revealed differences in the percent of nano-sized particles from 32%‒58%. Separation and enrichment of nano- and submicron-sized particles from commercial-grade E171 and E171 isolated from foodstuffs and pharmaceuticals was accomplished using rate-zonal centrifugation. Commercial-grade E171 was separated into nano- and submicron-enriched fractions consisting of a nano:submicron fraction of approximately 0.45:1 and 3.2:1, respectively. E171 extracted from gum had nano:submicron fractions of 1.4:1 and 0.19:1 for nano- and submicron-enriched, respectively. We show a difference in particle adhesion to the cell surface, which was found to be dependent on particle size and epithelial orientation. Finally, we provide evidence that E171 particles are not immediately cytotoxic to the Caco-2 human intestinal epithelium model. These data suggest that this separation method is appropriate for studies interested in isolating the nano-sized particle fraction taken directly from consumer products, in order to study separately the effects of nano and submicron particles. PMID:27798677

A Facile Method for Separating and Enriching Nano and Submicron Particles from Titanium Dioxide Found in Food and Pharmaceutical Products.

Science.gov (United States)

Faust, James J; Doudrick, Kyle; Yang, Yu; Capco, David G; Westerhoff, Paul

2016-01-01

Recent studies indicate the presence of nano-scale titanium dioxide (TiO2) as an additive in human foodstuffs, but a practical protocol to isolate and separate nano-fractions from soluble foodstuffs as a source of material remains elusive. As such, we developed a method for separating the nano and submicron fractions found in commercial-grade TiO2 (E171) and E171 extracted from soluble foodstuffs and pharmaceutical products (e.g., chewing gum, pain reliever, and allergy medicine). Primary particle analysis of commercial-grade E171 indicated that 54% of particles were nano-sized (i.e., E171 and E171 isolated from foodstuffs and pharmaceuticals was accomplished using rate-zonal centrifugation. Commercial-grade E171 was separated into nano- and submicron-enriched fractions consisting of a nano:submicron fraction of approximately 0.45:1 and 3.2:1, respectively. E171 extracted from gum had nano:submicron fractions of 1.4:1 and 0.19:1 for nano- and submicron-enriched, respectively. We show a difference in particle adhesion to the cell surface, which was found to be dependent on particle size and epithelial orientation. Finally, we provide evidence that E171 particles are not immediately cytotoxic to the Caco-2 human intestinal epithelium model. These data suggest that this separation method is appropriate for studies interested in isolating the nano-sized particle fraction taken directly from consumer products, in order to study separately the effects of nano and submicron particles.

Deep sub-micron FD-SOI for front-end application

International Nuclear Information System (INIS)

Ikeda, H.; Arai, Y.; Hara, K.; Hayakawa, H.; Hirose, K.; Ikegami, Y.; Ishino, H.; Kasaba, Y.; Kawasaki, T.; Kohriki, T.; Martin, E.; Miyake, H.; Mochizuki, A.; Tajima, H.; Tajima, O.; Takahashi, T.; Takashima, T.; Terada, S.; Tomita, H.; Tsuboyama, T.

2007-01-01

In order to confirm benefits of a deep sub-micron FD-SOI and to identify possible issues concerning front-end circuits with the FD-SOI, we have submitted a small design to Oki Electric Industry Co., Ltd. via the multi-chip project service of VDEC, the University of Tokyo. The initial test results and future plans for development are presented

Highly nonlinear sub-micron silicon nitride trench waveguide coated with gold nanoparticles

Science.gov (United States)

Huang, Yuewang; Zhao, Qiancheng; Sharac, Nicholas; Ragan, Regina; Boyraz, Ozdal

2015-05-01

We demonstrate the fabrication of a highly nonlinear sub-micron silicon nitride trench waveguide coated with gold nanoparticles for plasmonic enhancement. The average enhancement effect is evaluated by measuring the spectral broadening effect caused by self-phase-modulation. The nonlinear refractive index n2 was measured to be 7.0917×10-19 m2/W for a waveguide whose Wopen is 5 μm. Several waveguides at different locations on one wafer were measured in order to take the randomness of the nanoparticle distribution into consideration. The largest enhancement is measured to be as high as 10 times. Fabrication of this waveguide started with a MEMS grade photomask. By using conventional optical lithography, the wide linewidth was transferred to a wafer. Then the wafer was etched anisotropically by potassium hydroxide (KOH) to engrave trapezoidal trenches with an angle of 54.7º. Side wall roughness was mitigated by KOH etching and thermal oxidation that was used to generate a buffer layer for silicon nitride waveguide. The guiding material silicon nitride was then deposited by low pressure chemical vapor deposition. The waveguide was then patterned with a chemical template, with 20 nm gold particles being chemically attached to the functionalized poly(methyl methacrylate) domains. Since the particles attached only to the PMMA domains, they were confined to localized regions, therefore forcing the nanoparticles into clusters of various numbers and geometries. Experiments reveal that the waveguide has negligible nonlinear absorption loss, and its nonlinear refractive index can be greatly enhanced by gold nano clusters. The silicon nitride trench waveguide has large nonlinear refractive index, rendering itself promising for nonlinear applications.

Ligand-free gold atom clusters adsorbed on graphene nano sheets generated by oxidative laser fragmentation in water

Science.gov (United States)

Lau, Marcus; Haxhiaj, Ina; Wagener, Philipp; Intartaglia, Romuald; Brandi, Fernando; Nakamura, Junji; Barcikowski, Stephan

2014-08-01

Over three decades after the first synthesis of stabilized Au55-clusters many scientific questions about gold cluster properties are still unsolved and ligand-free colloidal clusters are difficult to fabricate. Here we present a novel route to produce ultra-small gold particles by using a green technique, the laser ablation and fragmentation in water, without using reductive or stabilizing agents at any step of the synthesis. For fabrication only a pulsed laser, a gold-target, pure water, sodium hydroxide and hydrogen peroxide are deployed. The particles are exemplarily hybridized to graphene supports showing that these carbon-free colloidal clusters might serve as versatile building blocks.

Correlated proton-electron hole dynamics in protonated water clusters upon extreme ultraviolet photoionization

Directory of Open Access Journals (Sweden)

Zheng Li

2016-07-01

Full Text Available The ultrafast nuclear and electronic dynamics of protonated water clusters H+(H2On after extreme ultraviolet photoionization is investigated. In particular, we focus on cluster cations with n = 3, 6, and 21. Upon ionization, two positive charges are present in the cluster related to the excess proton and the missing electron, respectively. A correlation is found between the cluster's geometrical conformation and initial electronic energy with the size of the final fragments produced. For situations in which the electron hole and proton are initially spatially close, the two entities become correlated and separate in a time-scale of 20 to 40 fs driven by strong non-adiabatic effects.

Correlated proton-electron hole dynamics in protonated water clusters upon extreme ultraviolet photoionization

Science.gov (United States)

Li, Zheng; Vendrell, Oriol

2016-01-01

The ultrafast nuclear and electronic dynamics of protonated water clusters H+(H2O)n after extreme ultraviolet photoionization is investigated. In particular, we focus on cluster cations with n = 3, 6, and 21. Upon ionization, two positive charges are present in the cluster related to the excess proton and the missing electron, respectively. A correlation is found between the cluster's geometrical conformation and initial electronic energy with the size of the final fragments produced. For situations in which the electron hole and proton are initially spatially close, the two entities become correlated and separate in a time-scale of 20 to 40 fs driven by strong non-adiabatic effects. PMID:26798842

Accurate Energies and Structures for Large Water Clusters Using the X3LYP Hybrid Density Functional

OpenAIRE

Su, Julius T.; Xu, Xin; Goddard, William A., III

2004-01-01

We predict structures and energies of water clusters containing up to 19 waters with X3LYP, an extended hybrid density functional designed to describe noncovalently bound systems as accurately as covalent systems. Our work establishes X3LYP as the most practical ab initio method today for calculating accurate water cluster structures and energies. We compare X3LYP/aug-cc-pVTZ energies to the most accurate theoretical values available (n = 2−6, 8), MP2 with basis set superposition error (BSSE)...

Computational studies of atmospherically-relevant chemical reactions in water clusters and on liquid water and ice surfaces.

Science.gov (United States)

Gerber, R Benny; Varner, Mychel E; Hammerich, Audrey D; Riikonen, Sampsa; Murdachaew, Garold; Shemesh, Dorit; Finlayson-Pitts, Barbara J

2015-02-17

CONSPECTUS: Reactions on water and ice surfaces and in other aqueous media are ubiquitous in the atmosphere, but the microscopic mechanisms of most of these processes are as yet unknown. This Account examines recent progress in atomistic simulations of such reactions and the insights provided into mechanisms and interpretation of experiments. Illustrative examples are discussed. The main computational approaches employed are classical trajectory simulations using interaction potentials derived from quantum chemical methods. This comprises both ab initio molecular dynamics (AIMD) and semiempirical molecular dynamics (SEMD), the latter referring to semiempirical quantum chemical methods. Presented examples are as follows: (i) Reaction of the (NO(+))(NO3(-)) ion pair with a water cluster to produce the atmospherically important HONO and HNO3. The simulations show that a cluster with four water molecules describes the reaction. This provides a hydrogen-bonding network supporting the transition state. The reaction is triggered by thermal structural fluctuations, and ultrafast changes in atomic partial charges play a key role. This is an example where a reaction in a small cluster can provide a model for a corresponding bulk process. The results support the proposed mechanism for production of HONO by hydrolysis of NO2 (N2O4). (ii) The reactions of gaseous HCl with N2O4 and N2O5 on liquid water surfaces. Ionization of HCl at the water/air interface is followed by nucleophilic attack of Cl(-) on N2O4 or N2O5. Both reactions proceed by an SN2 mechanism. The products are ClNO and ClNO2, precursors of atmospheric atomic chlorine. Because this mechanism cannot result from a cluster too small for HCl ionization, an extended water film model was simulated. The results explain ClNO formation experiments. Predicted ClNO2 formation is less efficient. (iii) Ionization of acids at ice surfaces. No ionization is found on ideal crystalline surfaces, but the process is efficient on

Submicron-bubble-enhanced focused ultrasound for blood-brain barrier disruption and improved CNS drug delivery.

Directory of Open Access Journals (Sweden)

Ching-Hsiang Fan

Full Text Available The use of focused ultrasound (FUS with microbubbles has been proven to induce transient blood-brain barrier opening (BBB-opening. However, FUS-induced inertial cavitation of microbubbles can also result in erythrocyte extravasations. Here we investigated whether induction of submicron bubbles to oscillate at their resonant frequency would reduce inertial cavitation during BBB-opening and thereby eliminate erythrocyte extravasations in a rat brain model. FUS was delivered with acoustic pressures of 0.1-4.5 MPa using either in-house manufactured submicron bubbles or standard SonoVue microbubbles. Wideband and subharmonic emissions from bubbles were used to quantify inertial and stable cavitation, respectively. Erythrocyte extravasations were evaluated by in vivo post-treatment magnetic resonance susceptibility-weighted imaging, and finally by histological confirmation. We found that excitation of submicron bubbles with resonant frequency-matched FUS (10 MHz can greatly limit inertial cavitation while enhancing stable cavitation. The BBB-opening was mainly caused by stable cavitation, whereas the erythrocyte extravasation was closely correlated with inertial cavitation. Our technique allows extensive reduction of inertial cavitation to induce safe BBB-opening. Furthermore, the safety issue of BBB-opening was not compromised by prolonging FUS exposure time, and the local drug concentrations in the brain tissues were significantly improved to 60 times (BCNU; 18.6 µg versus 0.3 µg by using chemotherapeutic agent-loaded submicron bubbles with FUS. This study provides important information towards the goal of successfully translating FUS brain drug delivery into clinical use.

Characteristics of scandate-impregnated cathodes with sub-micron scandia-doped matrices

International Nuclear Information System (INIS)

Yuan Haiqing; Gu Xin; Pan Kexin; Wang Yiman; Liu Wei; Zhang Ke; Wang Jinshu; Zhou Meiling; Li Ji

2005-01-01

We describe in this paper scandate-impregnated cathodes with sub-micron scandia-doped tungsten matrices having an improved uniformity of the Sc distribution. The scandia-doped tungsten powders were made by both liquid-solid doping and liquid-liquid doping methods on the basis of previous research. By improving pressing, sintering and impregnating procedures, we have obtained scandate-impregnated cathodes with a good uniformity of the Sc 2 O 3 - distribution. The porosity of the sub-micron structure matrix and content of impregnants inside the matrix are similar to those of conventionally impregnated cathodes. Space charge limited current densities of more than 30 A/cm 2 at 850 deg. C b have been obtained in a reproducible way. The current density continuously increases during the first 2000 h life test at 950 deg. C b with a dc load of 2 A/cm 2 and are stable for at least 3000 h

Sintering mantle mineral aggregates with submicron grains: examples of olivine and clinopyroxene

Science.gov (United States)

Tsubokawa, Y.; Ishikawa, M.

2017-12-01

Physical property of the major mantle minerals play an important role in the dynamic behavior of the Earth's mantle. Recently, it has been found that nano- to sub-micron scale frictional processes might control faulting processes and earthquake instability, and ultrafine-grained mineral aggregates thus have attracted the growing interest. Here we investigated a method for preparing polycrystalline clinoyproxene and polycrystalline olivine with grain size of sub-micron scale from natural crystals, two main constituents of the upper mantle. Nano-sized powders of both minerals are sintered under argon flow at temperatures ranging from 1130-1350 °C for 0.5-20 h. After sintering at 1180 °C and 1300 °C, we successfully fabricated polycrystalline clinopyroxene and polycrystalline olivine with grain size of physical properties of Earth's mantle.

Evidence for the existence of water:ethanol clusters from o-Ps yields

International Nuclear Information System (INIS)

Smith, F.A.; Beling, C.D.

1982-01-01

Lifetime measurements have been made in mixtures of water and ethanol at 293 K. Fluctuations are observed in both o-Ps yield and decay rate as a function of water concentration with local maxima occurring at molecular ratios (EtOH:H 2 O) of 4:1 and 1:1. The results are interpreted in terms of cluster formation at these concentrations. (Auth.)

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.

Submicron and nano formulations of titanium dioxide and zinc oxide stimulate unique cellular toxicological responses in the green microalga Chlamydomonas reinhardtii

Energy Technology Data Exchange (ETDEWEB)

Gunawan, Cindy, E-mail: c.gunawan@unsw.edu.au [ARC Centre of Excellence for Functional Nanomaterials, School of Chemical Engineering, The University of New South Wales, Sydney, NSW (Australia); Sirimanoonphan, Aunchisa [ARC Centre of Excellence for Functional Nanomaterials, School of Chemical Engineering, The University of New South Wales, Sydney, NSW (Australia); Teoh, Wey Yang [Clean Energy and Nanotechnology (CLEAN) Laboratory, School of Energy and Environment, City University of Hong Kong, Kowloon, Hong Kong Special Administrative Region (Hong Kong); Marquis, Christopher P., E-mail: c.marquis@unsw.edu.au [School of Biotechnology and Biomolecular Sciences, The University of New South Wales, Sydney, NSW (Australia); Amal, Rose [ARC Centre of Excellence for Functional Nanomaterials, School of Chemical Engineering, The University of New South Wales, Sydney, NSW (Australia)

2013-09-15

Highlights: • Uptake of TiO{sub 2} solids by C. reinhardtii generates ROS as an early stress response. • Submicron and nanoTiO{sub 2} exhibit benign effect on cell proliferation. • Uptake of ZnO solids and leached zinc by C. reinhardtii inhibit the alga growth. • No cellular oxidative stress is detected with submicron and nano ZnO exposure. • The toxicity of particles is not necessarily mediated by cellular oxidative stress. -- Abstract: The work investigates the eco-cytoxicity of submicron and nano TiO{sub 2} and ZnO, arising from the unique interactions of freshwater microalga Chlamydomonas reinhardtii to soluble and undissolved components of the metal oxides. In a freshwater medium, submicron and nano TiO{sub 2} exist as suspended aggregates with no-observable leaching. Submicron and nano ZnO undergo comparable concentration-dependent fractional leaching, and exist as dissolved zinc and aggregates of undissolved ZnO. Cellular internalisation of solid TiO{sub 2} stimulates cellular ROS generation as an early stress response. The cellular redox imbalance was observed for both submicron and nano TiO{sub 2} exposure, despite exhibiting benign effects on the alga proliferation (8-day EC50 > 100 mg TiO{sub 2}/L). Parallel exposure of C. reinhardtii to submicron and nano ZnO saw cellular uptake of both the leached zinc and solid ZnO and resulting in inhibition of the alga growth (8-day EC50 ≥ 0.01 mg ZnO/L). Despite the sensitivity, no zinc-induced cellular ROS generation was detected, even at 100 mg ZnO/L exposure. Taken together, the observations confront the generally accepted paradigm of cellular oxidative stress-mediated cytotoxicity of particles. The knowledge of speciation of particles and the corresponding stimulation of unique cellular responses and cytotoxicity is vital for assessment of the environmental implications of these materials.

Submicron and nano formulations of titanium dioxide and zinc oxide stimulate unique cellular toxicological responses in the green microalga Chlamydomonas reinhardtii

International Nuclear Information System (INIS)

Gunawan, Cindy; Sirimanoonphan, Aunchisa; Teoh, Wey Yang; Marquis, Christopher P.; Amal, Rose

2013-01-01

Highlights: • Uptake of TiO 2 solids by C. reinhardtii generates ROS as an early stress response. • Submicron and nanoTiO 2 exhibit benign effect on cell proliferation. • Uptake of ZnO solids and leached zinc by C. reinhardtii inhibit the alga growth. • No cellular oxidative stress is detected with submicron and nano ZnO exposure. • The toxicity of particles is not necessarily mediated by cellular oxidative stress. -- Abstract: The work investigates the eco-cytoxicity of submicron and nano TiO 2 and ZnO, arising from the unique interactions of freshwater microalga Chlamydomonas reinhardtii to soluble and undissolved components of the metal oxides. In a freshwater medium, submicron and nano TiO 2 exist as suspended aggregates with no-observable leaching. Submicron and nano ZnO undergo comparable concentration-dependent fractional leaching, and exist as dissolved zinc and aggregates of undissolved ZnO. Cellular internalisation of solid TiO 2 stimulates cellular ROS generation as an early stress response. The cellular redox imbalance was observed for both submicron and nano TiO 2 exposure, despite exhibiting benign effects on the alga proliferation (8-day EC50 > 100 mg TiO 2 /L). Parallel exposure of C. reinhardtii to submicron and nano ZnO saw cellular uptake of both the leached zinc and solid ZnO and resulting in inhibition of the alga growth (8-day EC50 ≥ 0.01 mg ZnO/L). Despite the sensitivity, no zinc-induced cellular ROS generation was detected, even at 100 mg ZnO/L exposure. Taken together, the observations confront the generally accepted paradigm of cellular oxidative stress-mediated cytotoxicity of particles. The knowledge of speciation of particles and the corresponding stimulation of unique cellular responses and cytotoxicity is vital for assessment of the environmental implications of these materials

Kinetics of Sub-Micron Grain Size Refinement in 9310 Steel

Science.gov (United States)

Kozmel, Thomas; Chen, Edward Y.; Chen, Charlie C.; Tin, Sammy

2014-05-01

Recent efforts have focused on the development of novel manufacturing processes capable of producing microstructures dominated by sub-micron grains. For structural applications, grain refinement has been shown to enhance mechanical properties such as strength, fatigue resistance, and fracture toughness. Through control of the thermo-mechanical processing parameters, dynamic recrystallization mechanisms were used to produce microstructures consisting of sub-micron grains in 9310 steel. Starting with initial bainitic grain sizes of 40 to 50 μm, various levels of grain refinement were observed following hot deformation of 9310 steel samples at temperatures and strain rates ranging from 755 K to 922 K (482 °C and 649 °C) and 1 to 0.001/s, respectively. The resulting deformation microstructures were characterized using scanning electron microscopy and electron backscatter diffraction techniques to quantify the extent of carbide coarsening and grain refinement occurring during deformation. Microstructural models based on the Zener-Holloman parameter were developed and modified to include the effect of the ferrite/carbide interactions within the system. These models were shown to effectively correlate microstructural attributes to the thermal mechanical processing parameters.

Electrochemical filtration for turbidity removal in industrial cooling/process water systems

International Nuclear Information System (INIS)

Kumbhar, A.G.; Venkateswaran, G.

2008-01-01

Water samples of large cooling water reservoirs may look visibly clear and transparent, but still may contain sub-micron size particles at sub-parts-per-million levels. Deposition of these particles on heat exchanger surfaces, reduces the heat transfer efficiency in power industry. In nuclear power plants, additionally it creates radiation exposure problems due to activation of fine metallic turbidity in the reactor core and its subsequent transfer to out-of-core surfaces. Sub-micron filtration creates back high-pressure problem. Zeta filters available commercially are prescribed for separating either positively or negatively charged particles. They are of once-use and throw-type. Precipitation surface modified ion exchangers impart chemical impurities to the system. Thus, sub-micron size and dilute turbidity removal from large volumes of waters such as heat exchanger cooling water in nuclear and power industry poses a problem. Electro deposition of the turbidity causing particles, on porous carbon/graphite felt electrodes, is one of the best suited methods for turbidity removal from large volumes of water due to the filter's high permeability, inertness to the system and regenerability resulting in low waste generation. Initially, active indium turbidity removal from RAPS-1 heavy water moderator system, and microbes removal from heat exchanger cooling lake water of RAPS 1 and 2 were demonstrated with in-house designed and fabricated prototype electrochemical filter (ECF). Subsequently, a larger size, high flow filter was fabricated and deployed for iron turbidity removal from active process waters system of Kaiga Generation Station unit 1 and silica and iron turbidity removal from cooling water pond used for heat exchanger of a high temperature high pressure (HTHP) loop at WSCD, Kalpakkam. The ECF proved its exclusive utility for sub-micron size turbidity removal and microbes removal. ECF maneuverability with potential and current for both positively and

Production and characterization of protonated molecular clusters containing a given number of water molecules with the DIAM set-up

International Nuclear Information System (INIS)

Bruny, G.

2010-01-01

nano-scale characterization of irradiation in bio-molecular systems requires observation of novel features which are now achievable with the recent technical progress. This work is a central part in the development of DIAM which is a new experimental set-up devoted to irradiation of bio-molecular clusters at the Institut de Physique Nucleaire de Lyon. The development of the cluster source and of a double focusing mass spectrometer leads to the production of intense beams of mass selected protonated molecular clusters. Combined with this mass selected cluster beams an innovative detection technique is demonstrated in collision induced dissociation experiments. The results contribute to the knowledge of the stability and the structure of the small protonated water clusters and mixed clusters of water and pyridine. (author)

Submicron, soft x-ray fluorescence imaging

International Nuclear Information System (INIS)

La Fontaine, B.; MacDowell, A.A.; Tan, Z.; White, D.L.; Taylor, G.N.; Wood, O.R. II; Bjorkholm, J.E.; Tennant, D.M.; Hulbert, S.L.

1995-01-01

Submicron fluorescence imaging of soft x-ray aerial images, using a high resolution fluorescent crystal is reported. Features as small as 0.1 μm were observed using a commercially available single-crystal phosphor, STI-F10G (Star Tech Instruments Inc. P. O. Box 2536, Danbury, CT 06813-2536), excited with 139 A light. Its quantum efficiency was estimated to be 5--10 times that of sodium salicylate and to be constant over a broad spectral range from 30 to 400 A. A comparison with a terbium-activated yttrium orthosilicate fluorescent crystal is also presented. Several applications, such as the characterization of the aerial images produced by deep ultraviolet or extreme ultraviolet lithographic exposure tools, are envisaged

Lift-off process for deep-submicron-size junctions using supercritical CO2

International Nuclear Information System (INIS)

Fukushima, A.; Kubota, H.; Yuasa, S.; Takahachi, T.; Kadoriku, S.; Miyake, K.

2007-01-01

Deep-submicron-size (∼100-nm-size) junctions are a key element to investigate spin-torque transfer phenomena such as current induced magnetization reversal or the spin-torque diode effect. In the fabrication of submicron-size junctions using an etching method, the lift-off process after the etching process tends to be difficult as the size of junctions shrinks. In this study, we present a new lift-off process using supercritical CO 2 . In this process, the samples were immersed in solvent (mixture of N-Methyl-2-pyrrolidone and isopropanol), and pressurized by CO 2 gas. The CO 2 gas then went into supercritical phase and the solvent was removed by a continuous flow of CO 2 . We obtained considerable yield rate (success ratio in lift-off process) of more than 50% for the samples down to 100-nm-size junctions

Lung deposition of sub-micron aerosols calculated as a function of age and breathing rate

International Nuclear Information System (INIS)

James, A.C.

1978-01-01

Experimental measurements of lung deposition and especially of regional deposition, of aerosols in the sub-micron size range have been so few that it is worthwhile establishing a method of calculation. A computer routine has therefore been developed to calculate aerosol deposition in successive bronchial and bronchiolar generations of the Weibel 'A' model of human lung for the sub-micron size range where deposition occurs solely by diffusion. This model can be scaled to represent lungs at various ages and vital capacities. Some calculated results are presented here and compared with measurements of lung deposition made under carefully controlled conditions in humans. (author)

Fabrication of submicron structures in nanoparticle/polymer composite by holographic lithography and reactive ion etching

Science.gov (United States)

Zhang, A. Ping; He, Sailing; Kim, Kyoung Tae; Yoon, Yong-Kyu; Burzynski, Ryszard; Samoc, Marek; Prasad, Paras N.

2008-11-01

We report on the fabrication of nanoparticle/polymer submicron structures by combining holographic lithography and reactive ion etching. Silica nanoparticles are uniformly dispersed in a (SU8) polymer matrix at a high concentration, and in situ polymerization (cross-linking) is used to form a nanoparticle/polymer composite. Another photosensitive SU8 layer cast upon the nanoparticle/SU8 composite layer is structured through holographic lithography, whose pattern is finally transferred to the nanoparticle/SU8 layer by the reactive ion etching process. Honeycomb structures in a submicron scale are experimentally realized in the nanoparticle/SU8 composite.

Cluster analysis and quality assessment of logged water at an irrigation project, eastern Saudi Arabia.

Science.gov (United States)

Hussain, Mahbub; Ahmed, Syed Munaf; Abderrahman, Walid

2008-01-01

A multivariate statistical technique, cluster analysis, was used to assess the logged surface water quality at an irrigation project at Al-Fadhley, Eastern Province, Saudi Arabia. The principal idea behind using the technique was to utilize all available hydrochemical variables in the quality assessment including trace elements and other ions which are not considered in conventional techniques for water quality assessments like Stiff and Piper diagrams. Furthermore, the area belongs to an irrigation project where water contamination associated with the use of fertilizers, insecticides and pesticides is expected. This quality assessment study was carried out on a total of 34 surface/logged water samples. To gain a greater insight in terms of the seasonal variation of water quality, 17 samples were collected from both summer and winter seasons. The collected samples were analyzed for a total of 23 water quality parameters including pH, TDS, conductivity, alkalinity, sulfate, chloride, bicarbonate, nitrate, phosphate, bromide, fluoride, calcium, magnesium, sodium, potassium, arsenic, boron, copper, cobalt, iron, lithium, manganese, molybdenum, nickel, selenium, mercury and zinc. Cluster analysis in both Q and R modes was used. Q-mode analysis resulted in three distinct water types for both the summer and winter seasons. Q-mode analysis also showed the spatial as well as temporal variation in water quality. R-mode cluster analysis led to the conclusion that there are two major sources of contamination for the surface/shallow groundwater in the area: fertilizers, micronutrients, pesticides, and insecticides used in agricultural activities, and non-point natural sources.

Submicron hollow spot generation by solid immersion lens and structured illumination

NARCIS (Netherlands)

Kim, M.S.; Assafrao, A.C.; Scharf, T.; Wachters, A.J.H.; Pereira, S.F.; Urbach, H.P.; Brun, M.; Olivier, S.; Nicoletti, S.; Herzig, H.P.

2012-01-01

We report on the experimental and numerical demonstration of immersed submicron-size hollow focused spots, generated by structuring the polarization state of an incident light beam impinging on a micro-size solid immersion lens (?-SIL) made of SiO2. Such structured focal spots are characterized by a

Enhancement in electrical conductivity of pastes containing submicron Ag-coated Cu filler with palmitic acid surface modification

Science.gov (United States)

Choi, Eun Byeol; Lee, Jong-Hyun

2017-09-01

The fabrication and applied use of submicron Ag-coated Cu (Cu@Ag) particles as a filler material for epoxy-based conductive pastes having the advantages of a lower material cost and antioxidation behavior were studied. Submicron Cu@Ag particles were successfully prepared and surface-modified using palmitic acid. Diffuse reflectance infrared Fourier transform spectroscopy and thermogravimetric differential scanning calorimetry results indicated the formation of an organic layer by the chemical interaction between the Cu@Ag surface and palmitic acid and the survival of the organic layer after treatment at 160 °C for 3 h in air. The printed pastes containing both commercial micron Cu@Ag flakes and the fabricated submicron Cu@Ag particles showed a greatly reduced electrical resistivity (4.68 × 10-4 Ω cm) after surface modification compared to an initial value of 1.85 × 10-3 Ω cm when cured.

Separation of submicron particles from biofuel combustion with flue gas condensation or wet condensing electrostatic precipitator. Analysis of possibilities; Avskiljning av submikrona partiklar vid biobraenslefoerbraenning med roekgaskondensering eller kondenserande vaata elfilter. Analys av moejligheterna

Energy Technology Data Exchange (ETDEWEB)

Roennbaeck, Marie; Gustavsson, Lennart [Swedish National Testing and Research Inst., Boraas (Sweden)

2006-11-15

Dust particles in flue gas larger than 1 {mu}m are well separated by conventional techniques, while submicron particles are poorly separated. As the use of biofuels with high ash content is increasing, as well as knowledge about negative health effects from inhalation of submicron particles, the interest for reduction of emissions of submicron particles will probably increase. The aim of this project is to investigate possible techniques for separation of submicron particles during flue gas condensation through modification of conventional technique, or with available techniques not usually used with combustion of biofuels, e.g. a wet electrostatic precipitator. Mechanisms for separation of dust particles are briefly described. Cyclones separates particles larger than about 1 {mu}m. Fabric filters separates all particles sizes, but the efficiency reduces as the size reduces. In flue gas condensers and scrubbers the speed and size of water droplets are important for the reduction efficiency. Dry electrostatic precipitators work for all particle sizes, but with reduced efficiency for sizes between 0.1 and 3 {mu}m. Wet electrostatic precipitators separates submicron particles much better. One reason for this is that the potential between the electrodes can be higher. Among conventional flue gas condensers and scrubbers there are two types that, properly designed, can separate submicron particles, namely 'type venturi scrubbers', i.e. a scrubber where a high flue gas velocity is used to form many, small water droplets by friction forces in a nozzle, and 'type scrubber with nozzles', i.e. a scrubber where nozzles supply droplets to the flue gas. For a scrubber with nozzles, the falling velocity of the droplets must be lower and the size smaller than is common today. Also the wet electrostatic precipitator separates submicron particles with high efficiency. They are used today mainly for problematic particles, e.g. sticky or corrosive ones, or for

Clustering analysis of water distribution systems: identifying critical components and community impacts.

Science.gov (United States)

Diao, K; Farmani, R; Fu, G; Astaraie-Imani, M; Ward, S; Butler, D

2014-01-01

Large water distribution systems (WDSs) are networks with both topological and behavioural complexity. Thereby, it is usually difficult to identify the key features of the properties of the system, and subsequently all the critical components within the system for a given purpose of design or control. One way is, however, to more explicitly visualize the network structure and interactions between components by dividing a WDS into a number of clusters (subsystems). Accordingly, this paper introduces a clustering strategy that decomposes WDSs into clusters with stronger internal connections than external connections. The detected cluster layout is very similar to the community structure of the served urban area. As WDSs may expand along with urban development in a community-by-community manner, the correspondingly formed distribution clusters may reveal some crucial configurations of WDSs. For verification, the method is applied to identify all the critical links during firefighting for the vulnerability analysis of a real-world WDS. Moreover, both the most critical pipes and clusters are addressed, given the consequences of pipe failure. Compared with the enumeration method, the method used in this study identifies the same group of the most critical components, and provides similar criticality prioritizations of them in a more computationally efficient time.

Differential dynamic microscopy of weakly scattering and polydisperse protein-rich clusters

Science.gov (United States)

Safari, Mohammad S.; Vorontsova, Maria A.; Poling-Skutvik, Ryan; Vekilov, Peter G.; Conrad, Jacinta C.

2015-10-01

Nanoparticle dynamics impact a wide range of biological transport processes and applications in nanomedicine and natural resource engineering. Differential dynamic microscopy (DDM) was recently developed to quantify the dynamics of submicron particles in solutions from fluctuations of intensity in optical micrographs. Differential dynamic microscopy is well established for monodisperse particle populations, but has not been applied to solutions containing weakly scattering polydisperse biological nanoparticles. Here we use bright-field DDM (BDDM) to measure the dynamics of protein-rich liquid clusters, whose size ranges from tens to hundreds of nanometers and whose total volume fraction is less than 10-5. With solutions of two proteins, hemoglobin A and lysozyme, we evaluate the cluster diffusion coefficients from the dependence of the diffusive relaxation time on the scattering wave vector. We establish that for weakly scattering populations, an optimal thickness of the sample chamber exists at which the BDDM signal is maximized at the smallest sample volume. The average cluster diffusion coefficient measured using BDDM is consistently lower than that obtained from dynamic light scattering at a scattering angle of 90∘. This apparent discrepancy is due to Mie scattering from the polydisperse cluster population, in which larger clusters preferentially scatter more light in the forward direction.

Using self-consistent Gibbs free energy surfaces to calculate size distributions of neutral and charged clusters for the sulfuric acid-water binary system

Science.gov (United States)

Smith, J. A.; Froyd, K. D.; Toon, O. B.

2012-12-01

We construct tables of reaction enthalpies and entropies for the association reactions involving sulfuric acid vapor, water vapor, and the bisulfate ion. These tables are created from experimental measurements and quantum chemical calculations for molecular clusters and a classical thermodynamic model for larger clusters. These initial tables are not thermodynamically consistent. For example, the Gibbs free energy of associating a cluster consisting of one acid molecule and two water molecules depends on the order in which the cluster was assembled: add two waters and then the acid or add an acid and a water and then the second water. We adjust the values within the tables using the method of Lagrange multipliers to minimize the adjustments and produce self-consistent Gibbs free energy surfaces for the neutral clusters and the charged clusters. With the self-consistent Gibbs free energy surfaces, we calculate size distributions of neutral and charged clusters for a variety of atmospheric conditions. Depending on the conditions, nucleation can be dominated by growth along the neutral channel or growth along the ion channel followed by ion-ion recombination.

High-Q submicron-diameter quantum-dot microcavity pillars for cavity QED experiments

DEFF Research Database (Denmark)

Gregersen, Niels; Lermer, Matthias; Dunzer, Florian

As/AlAs micropillar design where Bloch-wave engineering is employed to significally enhance the cavity mode confinement in the submicron diameter regime. We demonstrate a record-high vacuum Rabi splitting of 85 µeV of the strong coupling for pillars incorporating quantum dots with modest oscillator strength f ≈ 10....... It is well-known that light-matter interaction depends on the photonic environment, and thus proper engineering of the optical mode in microcavity systems is central to obtaining the desired functionality. In the strong coupling regime, the visibility of the Rabi splitting is described by the light...... coupling in micropillars relied on quantum dots with high oscillator strengths f > 50, our advanced design allows for the observation of strong coupling for submicron diameter quantum dot-pillars with standard f ≈ 10 oscillator strength. A quality factor of 13600 and a vacuum Rabi splitting of 85 µe...

Cooperative effects in the structuring of fluoride water clusters: Ab initio hybrid quantum mechanical/molecular mechanical model incorporating polarizable fluctuating charge solvent

Science.gov (United States)

Bryce, Richard A.; Vincent, Mark A.; Malcolm, Nathaniel O. J.; Hillier, Ian H.; Burton, Neil A.

1998-08-01

A new hybrid quantum mechanical/molecular mechanical model of solvation is developed and used to describe the structure and dynamics of small fluoride/water clusters, using an ab initio wave function to model the ion and a fluctuating charge potential to model the waters. Appropriate parameters for the water-water and fluoride-water interactions are derived, with the fluoride anion being described by density functional theory and a large Gaussian basis. The role of solvent polarization in determining the structure and energetics of F(H2O)4- clusters is investigated, predicting a slightly greater stability of the interior compared to the surface structure, in agreement with ab initio studies. An extended Lagrangian treatment of the polarizable water, in which the water atomic charges fluctuate dynamically, is used to study the dynamics of F(H2O)4- cluster. A simulation using a fixed solvent charge distribution indicates principally interior, solvated states for the cluster. However, a preponderance of trisolvated configurations is observed using the polarizable model at 300 K, which involves only three direct fluoride-water hydrogen bonds. Ab initio calculations confirm this trisolvated species as a thermally accessible state at room temperature, in addition to the tetrasolvated interior and surface structures. Extension of this polarizable water model to fluoride clusters with five and six waters gave less satisfactory agreement with experimental energies and with ab initio geometries. However, our results do suggest that a quantitative model of solvent polarization is fundamental for an accurate understanding of the properties of anionic water clusters.

Properties of submicron particles in Atmospheric Brown Clouds

Science.gov (United States)

Adushkin, V. V.; Chen, B. B.; Dubovskoi, A. N.; Friedrich, F.; Pernik, L. M.; Popel, S. I.; Weidler, P. G.

2010-05-01

The Atmospheric Brown Clouds (ABC) is an important problem of this century. Investigations of last years and satellite data show that the ABC (or brown gas, smog, fog) cover extensive territories including the whole continents and oceans. The brown gas consists of a mixture of particles of anthropogenic sulfates, nitrates, organic origin, black carbon, dust, ashes, and also natural aerosols such as sea salt and mineral dust. The brown color is a result of absorption and scattering of solar radiation by the anthropogenic black carbon, ashes, the particles of salt dust, and nitrogen dioxide. The investigation of the ABC is a fundamental problem for prevention of degradation of the environment. At present in the CIS in-situ investigations of the ABC are carried out on Lidar Station Teplokluchenka (Kyrgyz Republic). Here, we present the results of experimental investigation of submicron (nanoscale) particles originating from the ABC and the properties of the particles. Samples of dust precipitating from the ABC were obtained at the area of Lidar Station Teplokluchenka as well as scientific station of the Russian Academy of Sciences near Bishkek. The data for determination of the grain composition were obtained with the aid of the scanning electron microscopes JEOL 6460 LV and Philips XL 30 FEG. Analysis of the properties of the particles was performed by means of the X-ray diffraction using diffractometer Siemens D5000. The images of the grains were mapped. The investigation allows us to get (after the image processing) the grain composition within the dust particle size range of 60 nm to 700 μm. Distributions of nano- and microscale particles in sizes were constructed using Rozin-Rammler coordinates. Analysis of the distributions shows that the ABC contain submicron (nanoscale) particles; 2) at higher altitudes the concentration of the submicron (nanoscale) particles in the ABC is higher than at lower altitudes. The chemical compositions of the particles are shown to

Submicron beam X-ray diffraction of nanoheteroepitaxily grown GaN: Experimental challenges and calibration procedures

Energy Technology Data Exchange (ETDEWEB)

Bonanno, P.L., E-mail: PeterBonanno@gatech.ed [Georgia Institute of Technology/GTL, UMI 2958 Georgia Tech-CNRS, 57070 Metz (France); Gautier, S. [Laboratoire Materiaux Optiques, Photonique et Micro-Nano Systemes, UMR CNRS 7132, Universite de Metz et SUPELEC, 2 rue E. Belin, 57070 Metz (France); Sirenko, A.A. [Department of Physics, New Jersey Institute of Technology, Newark, NJ 07102 (United States); Kazimirov, A. [Cornell High Energy Synchrotron Source (CHESS), Cornell University, Ithaca, New York 14853 (United States); Cai, Z.-H. [Advanced Photon Source, 9700 S. Cass Avenue, Argonne, IL 60439 (United States); Goh, W.H. [Georgia Institute of Technology/GTL, UMI 2958 Georgia Tech-CNRS, 57070 Metz (France); Martin, J. [Laboratoire Materiaux Optiques, Photonique et Micro-Nano Systemes, UMR CNRS 7132, Universite de Metz et SUPELEC, 2 rue E. Belin, 57070 Metz (France); Martinez, A. [Laboratoire de Photonique et de Nanostructures, UPR CNRS 20, Route de Nozay, 91460 Marcoussis (France); Moudakir, T. [Laboratoire Materiaux Optiques, Photonique et Micro-Nano Systemes, UMR CNRS 7132, Universite de Metz et SUPELEC, 2 rue E. Belin, 57070 Metz (France); Maloufi, N. [Laboratoire d' Etude des Textures et Application aux Materiaux, UMR CNRS 7078, Ile du Saulcy, 57045 Metz Cedex 1 (France); Assouar, M.B. [Laboratoire de Physique des Milieux Ionises et Applications, Nancy University, CNRS, BP 239, F-54506 Vandoeuvre-les-Nancy Cedex (France); Ramdane, A.; Gratiet, L. Le [Laboratoire de Photonique et de Nanostructures, UPR CNRS 20, Route de Nozay, 91460 Marcoussis (France); Ougazzaden, A. [Georgia Institute of Technology/GTL, UMI 2958 Georgia Tech-CNRS, 57070 Metz (France)

2010-02-15

Highly relaxed GaN nanodots and submicron ridges have been selectively grown in the NSAG regime using MOVPE on lattice mismatched 6H-SiC and AlN substrates. 2D real space and 3D reciprocal space mapping was performed with a CCD detector using 10.4 keV synchrotron X-ray radiation at the 2-ID-D micro-diffraction beamline at Advanced Photon Source (APS). Calibration procedures have been developed to overcome the unique challenges of analyzing NSAG structures grown on highly mismatched substrates. We studied crystallographic planar bending on the submicron scale and found its correlation with strain relaxation in the NSAG ridges.

Anionic water pentamer and hexamer clusters: An extensive study of structures and energetics

Science.gov (United States)

Ünal, Aslı; Bozkaya, Uǧur

2018-03-01

An extensive study of structures and energetics for anionic pentamer and hexamer clusters is performed employing high level ab initio quantum chemical methods, such as the density-fitted orbital-optimized linearized coupled-cluster doubles (DF-OLCCD), coupled-cluster singles and doubles (CCSD), and coupled-cluster singles and doubles with perturbative triples [CCSD(T)] methods. In this study, sixteen anionic pentamer clusters and eighteen anionic hexamer clusters are reported. Relative, binding, and vertical detachment energies (VDE) are presented at the complete basis set limit (CBS), extrapolating energies of aug4-cc-pVTZ and aug4-cc-pVQZ custom basis sets. The largest VDE values obtained at the CCSD(T)/CBS level are 9.9 and 11.2 kcal mol-1 for pentamers and hexamers, respectively, which are in very good agreement with the experimental values of 9.5 and 11.1 kcal mol-1. Our binding energy results, at the CCSD(T)/CBS level, indicate strong bindings in anionic clusters due to hydrogen bond interactions. The average binding energy per water molecules is -5.0 and -5.3 kcal mol-1 for pentamers and hexamers, respectively. Furthermore, our results demonstrate that the DF-OLCCD method approaches to the CCSD(T) quality for anionic clusters. The inexpensive analytic gradients of DF-OLCCD compared to CCSD or CCSD(T) make it very attractive for high-accuracy studies.

Individual domain wall resistance in submicron ferromagnetic structures.

Science.gov (United States)

Danneau, R; Warin, P; Attané, J P; Petej, I; Beigné, C; Fermon, C; Klein, O; Marty, A; Ott, F; Samson, Y; Viret, M

2002-04-15

The resistance generated by individual domain walls is measured in a FePd nanostructure. Combining transport and magnetic imaging measurements, the intrinsic domain wall resistance is quantified. It is found positive and of a magnitude consistent with that predicted by models based on spin scattering effects within the walls. This magnetoresistance at a nanometer scale allows a direct counting of the number of walls inside the nanostructure. The effect is then used to measure changes in the magnetic configuration of submicron stripes under application of a magnetic field.

On the mechanism of water cluster-ion formation in carbon dioxide

International Nuclear Information System (INIS)

Warneck, P.; Rakshit, A.B.

1981-01-01

A drift chamber mass spectrometer has been used to study the formation of water cluster-ions in carbon dioxide containing traces of water vapour. The dominant reaction sequences were identified up to the fourth generation of daughter ions starting with CO 2 + . The subsequent reaction mechanism remains uncertain and several possibilities are discussed. The final ions are H 3 O + H 2 O and H 3 O + (H 2 O) 2 . The significance of the reaction schemes to the radiation chemistry of carbon dioxide is pointed out. (orig.)

Characterization of in-situ annealed sub-micron thick Cu(In,Ga)Se{sub 2} thin films

Energy Technology Data Exchange (ETDEWEB)

Ko, Byoung-Soo; Sung, Shi-Joon; Hwang, Dae-Kue, E-mail: dkhwang@dgist.ac.kr

2015-09-01

Sub-micron thick Cu(In,Ga)Se{sub 2} (CIGS) thin films were deposited on Mo-coated soda-lime glass substrates under various conditions by single-stage co-evaporation. Generally, the short circuit current (J{sub sc}) decreased with the decreasing thickness of the absorber layer. However, in this study, J{sub sc} was nearly unchanged with decreasing thickness, while the open circuit voltage (V{sub oc}) and fill factor (FF) decreased by 31.9 and 31.1%, respectively. We believe that the remarkable change of V{sub oc} and FF can be attributed to the difference in the total amount of injected thermal energy. Using scanning electron microscopy, we confirmed that the surface morphology becomes smooth and the grain size increased after the annealing process. In the X-ray diffraction patterns, the CIGS thin film also showed an improved crystal quality. We observed that the electric properties were improved by the in-situ annealing of CIGS thin films. The reverse saturation current density of the annealed CIGS solar cell was 100 times smaller than that of reference solar cell. Thus, sub-micron CIGS thin films annealed under a constant Se rate showed a 64.7% improvement in efficiency. - Highlights: • The effects of in-situ annealing the sub-micron CIGS film have been investigated. • The surface morphology and the grain size were improved by in-situ annealing. • The V{sub oc} and FF of the films were increased by about 30% after in-situ annealing. • In-situ annealing of sub-micron thick CIGS films can be improved an efficiency.

Submicron particle mass concentrations and sources in the Amazonian wet season (AMAZE-08)

Energy Technology Data Exchange (ETDEWEB)

Chen, Q.; Farmer, D. K.; Rizzo, L. V.; Pauliqueivis, T.; Kuwata, Mikinori; Karl, Thomas G.; Guenther, Alex B.; Allan, James D.; Coe, H.; Andreae, M. O.; Poeschl, U.; Jiminez, J. L.; Artaxo, Paulo; Martin, Scot T.

2015-01-01

Real-time mass spectra of non-refractory component of submicron aerosol particles were recorded in a tropical rainforest in the central Amazon basin during the wet season of 2008, as a part of the Amazonian Aerosol Characterization Experiment (AMAZE-08). Organic components accounted on average for more than 80% of the non-refractory submicron particle mass concentrations during the period of measurements. Ammonium was present in sufficient quantities to halfway neutralize sulfate. In this acidic, isoprene-dominated, low-NOx environment the high-resolution mass spectra as well as mass closures with ion chromatography measurements did not provide evidence for significant contributions of organosulfate species, at least at concentrations above uncertainty levels. Positive-matrix factorization of the time series of particle mass spectra identified four statistical factors to account for the variance of the signal intensities of the organic constituents: a factor HOA having a hydrocarbon-like signature and identified as regional emissions of primary organic material, a factor OOA-1 associated with fresh production of secondary organic material by a mechanism of BVOC oxidation followed by gas-to-particle conversion, a factor OOA-2 consistent with reactive uptake of isoprene oxidation products, especially epoxydiols by acidic particles, and a factor OOA-3 associated with long range transport and atmospheric aging. The OOA-1, -2, and -3 factors had progressively more oxidized signatures. Diameter-resolved mass spectral markers also suggested enhanced reactive uptake of isoprene oxidation products to the accumulation mode for the OOA-2 factor, and such size partitioning can be indicative of in-cloud process. The campaign-average factor loadings were in a ratio of 1.1:1.0 for the OOA-1 compared to the OOA-2 pathway, suggesting the comparable importance of gas-phase compared to particle-phase (including cloud waters) production pathways of secondary organic material during

Block copolymer stabilized nonaqueous biocompatible sub-micron emulsions for topical applications.

Science.gov (United States)

Atanase, Leonard Ionut; Riess, Gérard

2013-05-20

Polyethylene glycol (PEG) 400/Miglyol 812 non-aqueous sub-micron emulsions were developed due to the fact that they are of interest for the design of drug-loaded biocompatible topical formulations. These types of emulsions were favourably stabilized by poly (2-vinylpyridine)-b-poly (butadiene) (P2VP-b-PBut) copolymer with DPBut>DP2VP, each of these sequences being well-adapted to the solubility parameters of PEG 400 and Miglyol 812, respectively. This type of block copolymers, which might limit the Ostwald ripening, appeared to be more efficient stabilizers than low molecular weight non-ionic surfactants. The emulsion characteristics, such as particle size, stability and viscosity at different shear rates were determined as a function of the phase ratio, the copolymer concentration and storage time. It was further shown that Acyclovir, as a model drug of low water solubility, could be incorporated into the PEG 400 dispersed phase, with no significant modification of the initial emulsion characteristics. Copyright © 2013 Elsevier B.V. All rights reserved.

Fabrication of submicron proteinaceous structures by direct laser writing

Energy Technology Data Exchange (ETDEWEB)

Serien, Daniela [Center for International Research on Integrative Biomedical Systems, Institute of Industrial Science, The University of Tokyo, 4-6-1 Komaba, Meguro-ku, 153-8505 Tokyo (Japan); Takeuchi, Shoji, E-mail: takeuchi@iis.u-tokyo.ac.jp [Center for International Research on Integrative Biomedical Systems, Institute of Industrial Science, The University of Tokyo, 4-6-1 Komaba, Meguro-ku, 153-8505 Tokyo (Japan); ERATO Takeuchi Biohybrid Innovation Project, Japan Science and Technology Agency, 4-6-1 Komaba, Meguro-ku, 153-8505 Tokyo (Japan)

2015-07-06

In this paper, we provide a characterization of truly free-standing proteinaceous structures with submicron feature sizes depending on the fabrication conditions by model-based analysis. Protein cross-linking of bovine serum albumin is performed by direct laser writing and two-photon excitation of flavin adenine dinucleotide. We analyze the obtainable fabrication resolution and required threshold energy for polymerization. The applied polymerization model allows prediction of fabrication conditions and resulting fabrication size, alleviating the application of proteinaceous structure fabrication.

Alpha chymotrypsin coated clusters of Fe3O4 nanoparticles for biocatalysis in low water media

Directory of Open Access Journals (Sweden)

Mukherjee Joyeeta

2012-11-01

Full Text Available Abstract Background Enzymes in low water containing non aqueous media are useful for organic synthesis. For example, hydrolases in such media can be used for synthetic purposes. Initial work in this area was carried out with lyophilized powders of enzymes. These were found to have poor activity. Drying (removing bulk water by precipitation turned out to be a better approach. As enzymes in such media are heterogeneous catalysts, spreading these precipitates over a large surface gave even better results. In this context, nanoparticles with their better surface to volume ratio provide obvious advantage. Magnetic nanoparticles have an added advantage of easy separation after the reaction. Keeping this in view, alpha chymotrypsin solution in water was precipitated over a stirred population of Fe3O4 nanoparticles in n-propanol. This led to alpha chymotrypsin activity coated over clusters of Fe3O4 nanoparticles. These preparations were found to have quite high transesterification activity in low water containing n-octane. Results Precipitation of alpha chymotrypsin over a stirred suspension of Fe3O4 nanoparticles (3.6 nm diameter led to the formation of enzyme coated clusters of nanoparticles (ECCNs. These clusters were also magnetic and their hydrodynamic diameter ranged from 1.2- 2.6 microns (as measured by dynamic light scattering. Transmission electron microscopy (TEM, showed that these clusters had highly irregular shapes. Transesterification assay of various clusters in anhydrous n-octane led to optimization of concentration of nanoparticles in suspension during precipitation. Optimized design of enzyme coated magnetic clusters of nanoparticles (ECCN 3 showed the highest initial rate of 465 nmol min-1 mg-1protein which was about 9 times higher as compared to the simple precipitates with an initial rate of 52 nmol min-1 mg-1 protein. Circular Dichroism (CD(with a spinning cell accessory showed that secondary structure content of the alpha

Multipole moments of water molecules in clusters and ice Ih from first principles calculations

International Nuclear Information System (INIS)

Batista, E.R.; Xantheas, S.S.; Jonsson, H.

1999-01-01

We have calculated molecular multipole moments for water molecules in clusters and in ice Ih by partitioning the charge density obtained from first principles calculations. Various schemes for dividing the electronic charge density among the water molecules were used. They include Bader close-quote s zero flux surfaces and Voronoi partitioning schemes. A comparison was also made with an induction model including dipole, dipole-quadrupole, quadrupole-quadrupole polarizability and first hyperpolarizability as well as fixed octopole and hexadecapole moments. We have found that the different density partitioning schemes lead to widely different values for the molecular multipoles, illustrating how poorly defined molecular multipoles are in clusters and condensed environments. For instance, the magnitude of the molecular dipole moment in ice Ih ranges between 2.3 D and 3.1 D depending on the partitioning scheme used. Within each scheme, though, the value for the molecular dipole moment in ice is larger than in the hexamer. The magnitude of the molecular dipole moment in the clusters shows a monotonic increase from the gas phase value to the one in ice Ih, with the molecular dipole moment in the water ring hexamer being smaller than the one in ice Ih for all the partitioning schemes used. copyright 1999 American Institute of Physics

Hydrogen bonding in (substituted benzene)·(water)n clusters with n≤4

International Nuclear Information System (INIS)

Barth, H.-D.; Buchhold, K.; Djafari, S.; Reimann, B.; Lommatzsch, U.; Brutschy, B.

1998-01-01

Infrared ion-depletion spectroscopy, a double resonance method combining vibrational predissociation with resonant two-photon ionization (R2PI) spectroscopy, has been applied to study mixed clusters of the type (substituted benzene)·(H 2 O) n with n≤4. The UV chromophores were p-difluorobenzene, fluorobenzene, benzene, toluene, p-xylene and anisole. From the IR depletion spectra in the region of the OH stretching vibrations it could be shown that the water molecules are attached as subclusters to the chromophores. Size and configuration of the subclusters could be deduced from the IR depletion spectra. In the anisole·(H 2 O) 1 a nd 2 complexes the water clusters form an ordinary hydrogen bond to the oxygen atom of the methoxy group. In all other mixed complexes a π-hydrogen bond is formed between one of the free OH groups of a water subcluster and the π-system of the chromophore. According to the strength of this interaction the frequency of the respective absorption band exhibits a characteristic red-shift which could be related to the total atomic charges in the aromatic ring. (Copyright (c) 1998 Elsevier Science B.V., Amsterdam. All rights reserved.)

Beschrijving van een verdampings-condensatie aerosol generator voor de produktie van submicron aerosol

NARCIS (Netherlands)

Feijt; A.*; Meulen; A.van der

1985-01-01

Dit rapport is een handleiding voor een bedrijfszeker, routinematig gebruik van een zgn. Evaporation-Condensation aerosol Conditioner. Met deze aerosol generatie apparatuur kunnen op stabiele, reproduceerbare manier zeer hoge concentraties (tot 1 miljoen deeltjes per cc) monodispers submicron

Microscopic solvation of a lithium atom in water-ammonia mixed clusters: solvent coordination and electron localization in presence of a counterion.

Science.gov (United States)

Pratihar, Subha; Chandra, Amalendu

2008-07-14

The microsolvation structures and energetics of water-ammonia mixed clusters containing a lithium atom, i.e., Li(H(2)O)(n)(NH(3)), n = 1-5, are investigated by means of ab initio theoretical calculations. Several structural aspects such as the solvent coordination to the metal ion and binding motifs of the free valence electron of the metal are investigated. We also study the energetics aspects such as the dependence of vertical ionization energies on the cluster size, and all these structural and energetics aspects are compared to the corresponding results of previously studied anionic water-ammonia clusters without a metal ion. It is found that the Li-O and Li-N interactions play a very important role in stabilizing the lithium-water-ammonia clusters, and the presence of these metal ion-solvent interactions also affect the characteristics of electron solvation in these clusters. This is seen from the spatial distribution of the singly occupied molecular orbital (SOMO) which holds the ejected valence electron of the Li atom. For very small clusters, SOMO electron density is found to exist mainly at the vicinity of the Li atom, whereas for larger clusters, it is distributed outside the first solvation shell. The free dangling hydrogens of water and ammonia molecules are involved in capturing the SOMO electron density. In some of the conformers, OH{e}HO and OH{e}HN types of interactions are found to be present. The presence of the metal ion at the center of the cluster ensures that the ejected electron is solvated at a surface state only, whereas both surface and interiorlike states were found for the free electron in the corresponding anionic clusters without a metal ion. The vertical ionization energies of the present clusters are found to be higher than the vertical detachment energies of the corresponding anionic clusters which signify a relatively stronger binding of the free electron in the presence of the positive metal counterion. The shifts in different

Ab initio study of neutral (TiO2)n clusters and their interactions with water and transition metal atoms

International Nuclear Information System (INIS)

Çakır, D; Gülseren, O

2012-01-01

We have systematically investigated the growth behavior and stability of small stoichiometric (TiO 2 ) n (n = 1-10) clusters as well as their structural, electronic and magnetic properties by using the first-principles plane wave pseudopotential method within density functional theory. In order to find out the ground state geometries, a large number of initial cluster structures for each n has been searched via total energy calculations. Generally, the ground state structures for the case of n = 1-9 clusters have at least one monovalent O atom, which only binds to a single Ti atom. However, the most stable structure of the n = 10 cluster does not have any monovalent O atom. On the other hand, Ti atoms are at least fourfold coordinated for the ground state structures for n ≥ 4 clusters. Our calculations have revealed that clusters prefer to form three-dimensional structures. Furthermore, all these stoichiometric clusters have nonmagnetic ground state. The formation energy and the highest occupied molecular orbital (HOMO)-lowest unoccupied molecular orbital (LUMO) gap for the most stable structure of (TiO 2 ) n clusters for each n have also been calculated. The formation energy and hence the stability increases as the cluster size grows. In addition, the interactions between the ground state structure of the (TiO 2 ) n cluster and a single water molecule have been studied. The binding energy (E b ) of the H 2 O molecule exhibits an oscillatory behavior with the size of the clusters. A single water molecule preferably binds to the cluster Ti atom through its oxygen atom, resulting an average binding energy of 1.1 eV. We have also reported the interaction of the selected clusters (n = 3, 4, 10) with multiple water molecules. We have found that additional water molecules lead to a decrease in the binding energy of these molecules to the (TiO 2 ) n clusters. Finally, the adsorption of transition metal (TM) atoms (V, Co and Pt) on the n = 10 cluster has been

CNTs in situ attached to α-Fe2O3 submicron spheres for enhancing lithium storage capacity.

Science.gov (United States)

Gao, Guo; Zhang, Qiang; Cheng, Xin-Bing; Qiu, Peiyu; Sun, Rongjin; Yin, Ting; Cui, Daxiang

2015-01-14

In this work, we developed a facile hydrothermal method for synthesis of hybrid α-Fe2O3-carbon nanotubes (CNTs) architectures (α-Fe2O3-CNTs-1 and α-Fe2O3-CNTs-2). The CNTs are in situ attached to the α-Fe2O3 submicron spheres and form three-dimensional network robust architectures. The increase in the amount of CNTs in the network α-Fe2O3-CNTs architectures will significantly enhance the cycling and rate performance, as the flexible and robust CNTs could ensure the fast electron transport pathways, enhance the electronic conductivity, and improve the structural stability of the electrode. As for pure α-Fe2O3 submicron spheres, the capacity decreased significantly and retained at 377.4 mAh g(-1) after 11 cycles, and the capacity has a slightly increasing trend at the following cycling. In contrast, the network α-Fe2O3-CNTs-2 electrode shows the most remarkable performance. At the 60th cycle, the capacity of network α-Fe2O3-CNTs-2 (764.5 mAh g(-1)) is 1.78 times than that of α-Fe2O3 submicron spheres (428.3 mAh g(-1)). The long-term cycling performance (1000 cycles) of samples at a high current density of 5 C showed that the capacity of α-Fe2O3 submicron spheres fade to ∼37.3 mAh g(-1) at the 400th cycle and gradually increased to ∼116.7 mAh g(-1) at the 1000th cycle. The capacity of network α-Fe2O3-CNTs-2 maintained at ∼220.2 mAh g(-1) before the 400th cycle, arrived at ∼326.5 mAh g(-1) in the 615th, cycle and retained this value until 1000th cycle. The network α-Fe2O3-CNTs-2 composite could significantly enhance the cycling and rate performance than pure α-Fe2O3 submicron spheres composite.

Practical Considerations for Detection and Characterization of Sub-Micron Particles in Protein Solutions by Nanoparticle Tracking Analysis.

Science.gov (United States)

Gruia, Flaviu; Parupudi, Arun; Polozova, Alla

2015-01-01

Nanoparticle Tracking Analysis (NTA) is an emerging analytical technique developed for detection, sizing, and counting of sub-micron particles in liquid media. Its feasibility for use in biopharmaceutical development was evaluated with particle standards and recombinant protein solutions. Measurements of aqueous suspensions of NIST-traceable polystyrene particle standards showed accurate particle concentration detection between 2 × 10(7) and 5 × 10(9) particles/mL. Sizing was accurate for particle standards up to 200 nm. Smaller than nominal value sizes were detected by NTA for the 300-900 nm particles. Measurements of protein solutions showed that NTA performance is solution-specific. Reduced sensitivity, especially in opalescent solutions, was observed. Measurements in such solutions may require sample dilution; however, common sample manipulations, such as dilution and filtration, may result in particle formation. Dilution and filtration case studies are presented to further illustrate such behavior. To benchmark general performance, NTA was compared against asymmetric flow field flow fractionation coupled with multi-angle light scattering (aF4-MALS) and dynamic light scattering, which are other techniques for sub-micron particles. Data shows that all three methods have limitations and may not work equally well under certain conditions. Nevertheless, the ability of NTA to directly detect and count sub-micron particles is a feature not matched by aF4-MALS or dynamic light scattering. Thorough characterization of particulate matter present in protein therapeutics is limited by the lack of analytical methods for particles in the sub-micron size range. Emerging techniques are being developed to bridge this analytical gap. In this study, Nanoparticle Tracking Analysis is evaluated as a potential tool for biologics development. Our results indicate that method performance is molecule-specific and may not work as well under all solution conditions, especially when

Lack of Dependence of the Sizes of the Mesoscopic Protein Clusters on Electrostatics.

Science.gov (United States)

Vorontsova, Maria A; Chan, Ho Yin; Lubchenko, Vassiliy; Vekilov, Peter G

2015-11-03

Protein-rich clusters of steady submicron size and narrow size distribution exist in protein solutions in apparent violation of the classical laws of phase equilibrium. Even though they contain a minor fraction of the total protein, evidence suggests that they may serve as essential precursors for the nucleation of ordered solids such as crystals, sickle-cell hemoglobin polymers, and amyloid fibrils. The cluster formation mechanism remains elusive. We use the highly basic protein lysozyme at nearly neutral and lower pH as a model and explore the response of the cluster population to the electrostatic forces, which govern numerous biophysical phenomena, including crystallization and fibrillization. We tune the strength of intermolecular electrostatic forces by varying the solution ionic strength I and pH and find that despite the weaker repulsion at higher I and pH, the cluster size remains constant. Cluster responses to the presence of urea and ethanol demonstrate that cluster formation is controlled by hydrophobic interactions between the peptide backbones, exposed to the solvent after partial protein unfolding that may lead to transient protein oligomers. These findings reveal that the mechanism of the mesoscopic clusters is fundamentally different from those underlying the two main classes of ordered protein solid phases, crystals and amyloid fibrils, and partial unfolding of the protein chain may play a significant role. Copyright © 2015 Biophysical Society. Published by Elsevier Inc. All rights reserved.

Prediction of settled water turbidity and optimal coagulant dosage in drinking water treatment plant using a hybrid model of k-means clustering and adaptive neuro-fuzzy inference system

Science.gov (United States)

Kim, Chan Moon; Parnichkun, Manukid

2017-11-01

Coagulation is an important process in drinking water treatment to attain acceptable treated water quality. However, the determination of coagulant dosage is still a challenging task for operators, because coagulation is nonlinear and complicated process. Feedback control to achieve the desired treated water quality is difficult due to lengthy process time. In this research, a hybrid of k-means clustering and adaptive neuro-fuzzy inference system ( k-means-ANFIS) is proposed for the settled water turbidity prediction and the optimal coagulant dosage determination using full-scale historical data. To build a well-adaptive model to different process states from influent water, raw water quality data are classified into four clusters according to its properties by a k-means clustering technique. The sub-models are developed individually on the basis of each clustered data set. Results reveal that the sub-models constructed by a hybrid k-means-ANFIS perform better than not only a single ANFIS model, but also seasonal models by artificial neural network (ANN). The finally completed model consisting of sub-models shows more accurate and consistent prediction ability than a single model of ANFIS and a single model of ANN based on all five evaluation indices. Therefore, the hybrid model of k-means-ANFIS can be employed as a robust tool for managing both treated water quality and production costs simultaneously.

Submicron aerosol organic functional groups, ions, and water content at the Centreville SEARCH site (Alabama), during SOAS campaign

Science.gov (United States)

Ruggeri, G.; Ergin, G.; Modini, R. L.; Takahama, S.

2013-12-01

The SOAS campaign was conducted from June 1 to July 15 of 2013 in order to understand the relationship between biogenic and anthropogenic emissions in the South East US1,2. In this study, the organic and inorganic composition of submicron aerosol in the Centreville SEARCH site was measured by Fourier Transform Infrared Spectroscopy (FTIR) and the Ambient Ion Monitor (AIM; URG Corporation), whereas the aerosol water content was measured with a Dry Ambient Aerosol Size Spectrometer (DAASS)3. Organic functional group analysis was performed on PM1 aerosol selected by cyclone and collected on teflon filters with a time resolution of 4-12 hours, using one inlet heated to 50 °C and the other operated either at ambient temperature or 70 °C 4. The AIM measured both condensed and gas phase composition with a time resolution of 1 hour, providing partitioning behavior of inorganic species such as NH3/NH4+, HNO3/NO3-. These measurements collectively permit calculation of pure-component vapor pressures of candidate organic compounds and activity coefficients of interacting components in the condensed phase, using models such as SIMPOL.15, E-AIM6, and AIOMFAC7. From these results, the water content of the aerosol is predicted, and a comparison between modeled and measured partitioning of inorganic compounds and water vapor are discussed, in addition to organic aerosol volatility prediction based on functional group analysis. [1]- Goldstein, A.H., et al., Biogenic carbon and anthropogenic pollutants combine to form a cooling haze over the southeastern United States. Proceedings of the National Academy of Sciences of the United States of America, 2009. 106(22), 8835-8840. [2]- Carlton, A.G., Turpin, B.J., 2013. Particle partitioning potential of organic compounds is highest in the Eastern US and driven by anthropogenic water. Atmospheric Chemistry and Physics Discussions 13, 12743-12770. [3]- Khlystov, A., Stanier, C.O., Takahama, S., Pandis, S.N., 2005. Water content of ambient

Evaluating model parameterizations of submicron aerosol scattering and absorption with in situ data from ARCTAS 2008

Directory of Open Access Journals (Sweden)

M. J. Alvarado

2016-07-01

Full Text Available Accurate modeling of the scattering and absorption of ultraviolet and visible radiation by aerosols is essential for accurate simulations of atmospheric chemistry and climate. Closure studies using in situ measurements of aerosol scattering and absorption can be used to evaluate and improve models of aerosol optical properties without interference from model errors in aerosol emissions, transport, chemistry, or deposition rates. Here we evaluate the ability of four externally mixed, fixed size distribution parameterizations used in global models to simulate submicron aerosol scattering and absorption at three wavelengths using in situ data gathered during the 2008 Arctic Research of the Composition of the Troposphere from Aircraft and Satellites (ARCTAS campaign. The four models are the NASA Global Modeling Initiative (GMI Combo model, GEOS-Chem v9-02, the baseline configuration of a version of GEOS-Chem with online radiative transfer calculations (called GC-RT, and the Optical Properties of Aerosol and Clouds (OPAC v3.1 package. We also use the ARCTAS data to perform the first evaluation of the ability of the Aerosol Simulation Program (ASP v2.1 to simulate submicron aerosol scattering and absorption when in situ data on the aerosol size distribution are used, and examine the impact of different mixing rules for black carbon (BC on the results. We find that the GMI model tends to overestimate submicron scattering and absorption at shorter wavelengths by 10–23 %, and that GMI has smaller absolute mean biases for submicron absorption than OPAC v3.1, GEOS-Chem v9-02, or GC-RT. However, the changes to the density and refractive index of BC in GC-RT improve the simulation of submicron aerosol absorption at all wavelengths relative to GEOS-Chem v9-02. Adding a variable size distribution, as in ASP v2.1, improves model performance for scattering but not for absorption, likely due to the assumption in ASP v2.1 that BC is present at a constant mass

A theoretical study of water equilibria: the cluster distribution versus temperature and pressure for (H2O)n, n = 1-60, and ice.

Science.gov (United States)

Lenz, Annika; Ojamäe, Lars

2009-10-07

The size distribution of water clusters at equilibrium is studied using quantum-chemical calculations in combination with statistical thermodynamics. The necessary energetic data is obtained by quantum-chemical B3LYP computations and through extrapolations from the B3LYP results for the larger clusters. Clusters with up to 60 molecules are included in the equilibrium computations. Populations of different cluster sizes are calculated using both an ideal gas model with noninteracting clusters and a model where a correction for the interaction energy is included analogous to the van der Waals law. In standard vapor the majority of the water molecules are monomers. For the ideal gas model at 1 atm large clusters [56-mer (0-120 K) and 28-mer (100-260 K)] dominate at low temperatures and separate to smaller clusters [21-22-mer (170-280 K) and 4-6-mer (270-320 K) and to monomers (300-350 K)] when the temperature is increased. At lower pressure the transition from clusters to monomers lies at lower temperatures and fewer cluster sizes are formed. The computed size distribution exhibits enhanced peaks for the clusters consisting of 21 and 28 water molecules; these sizes are for protonated water clusters often referred to as magic numbers. If cluster-cluster interactions are included in the model the transition from clusters to monomers is sharper (i.e., occurs over a smaller temperature interval) than when the ideal-gas model is used. Clusters with 20-22 molecules dominate in the liquid region. When a large icelike cluster is included it will dominate for temperatures up to 325 K for the noninteracting clusters model. Thermodynamic properties (C(p), DeltaH) were calculated with in general good agreement with experimental values for the solid and gas phase. A formula for the number of H-bond topologies in a given cluster structure is derived. For the 20-mer it is shown that the number of topologies contributes to making the population of dodecahedron-shaped cluster larger

Electrical measurements on submicronic synthetic conductors : carbon nanotubes

Energy Technology Data Exchange (ETDEWEB)

Langer, L [Unite de Physico-Chimie et de Physique des Materiaux, Univ. Catholique de Louvain, Louvain-la-Neuve (Belgium); Stockman, L [Lab. voor Vaste Stof-Fysika en Magnetisme, Katholieke Univ. Leuven (Belgium); Heremans, J P [Physics Dept., General Motors Research, Warren, MI (United States); Bayot, V [Unite de Physico-Chimie et de Physique des Materiaux, Univ. Catholique de Louvain, Louvain-la-Neuve (Belgium); Olk, C H [Physics Dept., General Motors Research, Warren, MI (United States); Haesendonck, C van [Lab. voor Vaste Stof-Fysika en Magnetisme, Katholieke Univ. Leuven (Belgium); Bruynseraede, Y [Lab. voor Vaste Stof-Fysika en Magnetisme, Katholieke Univ. Leuven (Belgium); Issi, J P [Unite de Physico-Chimie et de Physique des Materiaux, Univ. Catholique de Louvain, Louvain-la-Neuve (Belgium)

1995-03-15

The synthesis of very small samples has raised the need for a drastic miniaturization of the classical four-probe technique in order to realize electrical resistance measurements. Two methods to realize electrical contacts on very small fibers are described here. Using classical photolithography the electrical resistivity of a submicronic catalytic chemical vapour deposited filament is estimated. Scanning tunneling microscopy (STM) lithography allowed to attach small gold contacts to a small bundle (diameter 50 nm) of carbon nanotubes. This bundle is found to exhibit a semimetallic behavior at higher temperature and an unexpected drop of the electrical resistivity at lower temperature. (orig.)

Revealing isomerism in sodium-water clusters: Photoionization spectra of Na(H2O)n (n = 2-90).

Science.gov (United States)

Dierking, Christoph W; Zurheide, Florian; Zeuch, Thomas; Med, Jakub; Parez, Stanislav; Slavíček, Petr

2017-06-28

Soft ionization of sodium tagged polar clusters is increasingly used as a powerful technique for sizing and characterization of small aerosols with possible application, e.g., in atmospheric chemistry or combustion science. Understanding the structure and photoionization of the sodium doped clusters is critical for such applications. In this work, we report on measurements of photoionization spectra for sodium doped water clusters containing 2-90 water molecules. While most of the previous studies focused on the ionization threshold of the Na(H 2 O) n clusters, we provide for the first time full photoionization spectra, including the high-energy region, which are used as reference for a comparison with theory. As reported in previous work, we have seen an initial drop of the appearance ionization energy with cluster size to values of about 3.2 eV for nphotoionization spectrum. Simulations at elevated temperatures show an increased abundance of isomers with low ionization energies, an entropic effect enabling size selective infrared action spectroscopy, based on near threshold photoionization of Na(H 2 O) n clusters. In addition, simulations of the sodium pick-up process were carried out to study the gradual formation of the hydrated electron which is the basis of the sodium-tagging sizing.

Structural insights into the light-driven auto-assembly process of the water-oxidizing Mn4CaO5-cluster in photosystem II.

Science.gov (United States)

Zhang, Miao; Bommer, Martin; Chatterjee, Ruchira; Hussein, Rana; Yano, Junko; Dau, Holger; Kern, Jan; Dobbek, Holger; Zouni, Athina

2017-07-18

In plants, algae and cyanobacteria, Photosystem II (PSII) catalyzes the light-driven splitting of water at a protein-bound Mn 4 CaO 5 -cluster, the water-oxidizing complex (WOC). In the photosynthetic organisms, the light-driven formation of the WOC from dissolved metal ions is a key process because it is essential in both initial activation and continuous repair of PSII. Structural information is required for understanding of this chaperone-free metal-cluster assembly. For the first time, we obtained a structure of PSII from Thermosynechococcus elongatus without the Mn 4 CaO 5 -cluster. Surprisingly, cluster-removal leaves the positions of all coordinating amino acid residues and most nearby water molecules largely unaffected, resulting in a pre-organized ligand shell for kinetically competent and error-free photo-assembly of the Mn 4 CaO 5 -cluster. First experiments initiating (i) partial disassembly and (ii) partial re-assembly after complete depletion of the Mn 4 CaO 5 -cluster agree with a specific bi-manganese cluster, likely a di-µ-oxo bridged pair of Mn(III) ions, as an assembly intermediate.

Spatial clustering of metal and metalloid mixtures in unregulated water sources on the Navajo Nation - Arizona, New Mexico, and Utah, USA.

Science.gov (United States)

Hoover, Joseph H; Coker, Eric; Barney, Yolanda; Shuey, Chris; Lewis, Johnnye

2018-08-15

Contaminant mixtures are identified regularly in public and private drinking water supplies throughout the United States; however, the complex and often correlated nature of mixtures makes identification of relevant combinations challenging. This study employed a Bayesian clustering method to identify subgroups of water sources with similar metal and metalloid profiles. Additionally, a spatial scan statistic assessed spatial clustering of these subgroups and a human health metric was applied to investigate potential for human toxicity. These methods were applied to a dataset comprised of metal and metalloid measurements from unregulated water sources located on the Navajo Nation, in the southwest United States. Results indicated distinct subgroups of water sources with similar contaminant profiles and that some of these subgroups were spatially clustered. Several profiles had metal and metalloid concentrations that may have potential for human toxicity including arsenic, uranium, lead, manganese, and selenium. This approach may be useful for identifying mixtures in water sources, spatially evaluating the clusters, and help inform toxicological research investigating mixtures. Copyright © 2018 The Authors. Published by Elsevier B.V. All rights reserved.

Binding water to a PEG-linked flexible bichromophore: IR spectra of diphenoxyethane-(H{sub 2}O){sub n} clusters, n = 2-4

Energy Technology Data Exchange (ETDEWEB)

Walsh, Patrick S.; Buchanan, Evan G.; Gord, Joseph R.; Zwier, Timothy S., E-mail: zwier@purdue.edu [Department of Chemistry, Purdue University, 560 Oval Drive, West Lafayette, Indiana 47907-2084 (United States)

2015-04-21

The single-conformation infrared (IR) and ultraviolet (UV) spectroscopies of neutral 1,2-diphenoxyethane-(H{sub 2}O){sub n} clusters with n = 2-4 (labeled henceforth as 1:n) have been studied in a molecular beam using a combination of resonant two-photon ionization, IR-UV holeburning, and resonant ion-dip infrared (RIDIR) spectroscopies. Ground state RIDIR spectra in the OH and CH stretch regions were used to provide firm assignments for the structures of the clusters by comparing the experimental spectra with the predictions of calculations carried out at the density functional M05-2X/6-31+G(d) level of theory. At all sizes in this range, the water molecules form water clusters in which all water molecules engage in a single H-bonded network. Selective binding to the tgt monomer conformer of 1,2-diphenoxyethane (C{sub 6}H{sub 5}-O-CH{sub 2}-CH{sub 2}-O-C{sub 6}H{sub 5}, DPOE) occurs, since this conformer provides a binding pocket in which the two ether oxygens and two phenyl ring π clouds can be involved in stabilizing the water cluster. The 1:2 cluster incorporates a water dimer “chain” bound to DPOE much as it is in the 1:1 complex [E. G. Buchanan et al., J. Phys. Chem. Lett. 4, 1644 (2013)], with primary attachment via a double-donor water that bridges the ether oxygen of one phenoxy group and the π cloud of the other. Two conformers of the 1:3 cluster are observed and characterized, one that extends the water chain to a third molecule (1:3 chain) and the other incorporating a water trimer cycle (1:3 cycle). A cyclic water structure is also observed for the 1:4 cluster. These structural characterizations provide a necessary foundation for studies of the perturbations imposed on the two close-lying S{sub 1}/S{sub 2} excited states of DPOE considered in the adjoining paper [P. S. Walsh et al., J. Chem. Phys. 142, 154304 (2015)].

Airborne studies of submicron aerosol in the troposphere over West Siberia

Energy Technology Data Exchange (ETDEWEB)

Panchenko, M.V.; Zuev, V.E.; Belan, B.D.; Terpugova, S.A. [Institute of Atmospheric Optics, Tomsk (Russian Federation)

1996-04-01

Submicron fraction particles that have the longest lifespan and are included in almost all atmospheric processes are of special importance among the great variety of sizes of particles present in the atmosphere. Submicron particles mainly determine the opticle state of the atmosphere in the visible spectral range, essentially cause the absorption of infrared radiation and, since they are the products and participants in all aerosol-to-gas transformations, accumulate of a lot of various chemical compounds and transfer them to large distances. Investigation of the processes of the spatial-temporal variability of aerosol particles for different climatic zones of the earth is the experimental base for studying their effect on climatically and ecologically significant factors and estimating their unfavorable tendencies. The increasing anthropogenic loading of the earth`s atmosphere is creating an urgency for aerosol research. Regardless of how perfect the analytical and numerical methods of solving radiation problems may be, success in forecasting climatic change is mainly determined by the reliability of the experimental data on optical parameters of the atmosphere and of the description of their variability under the effect of external factors.

Synergistic effect of PLGA nanoparticles and submicron triglyceride droplets in enhancing the intestinal solubilisation of a lipophilic weak base.

Science.gov (United States)

Joyce, Paul; Prestidge, Clive A

2018-06-15

A novel hybrid microparticulate system composed of poly(lactic-co-glycolic) acid (PLGA) nanoparticles and submicron medium-chain triglyceride (MCT) droplets was fabricated to overcome the pH-dependent solubility and precipitation challenges associated with a model poorly water-soluble weak base, cinnarizine (CIN). Molecular CIN was confined within both the lipid and polymer phase of PLGA-lipid hybrid (PLH) and PLGA-lipid-mannitol hybrid (PLMH) particles, which offered significant biopharmaceutical advantages in comparison to the unformulated drug, submicron MCT droplets and PLGA nanoparticles. This was highlighted by a substantial reduction in the pH-induced precipitation during in vitro gastrointestinal two-step dissolution studies. A >2.5-fold solubilisation enhancement was observed for the composite particles during simulated intestinal conditions, compared to pure CIN. Furthermore, the drug solubilisation capacity during in vitro intestinal digesting conditions was ~2-2.5 times greater for PLMH particles compared to the precursor emulsion droplets and PLGA nanoparticles. The observations from this study indicate that a synergy exists between the degradation products of PLGA nanoparticles and lipid droplets, whereby the dual-phase release and dissolution mechanism of the hybrid particles aids in prolonging pH-provoked precipitation. Subsequently, the ability for PLGA polymers and oligomers to act as polymeric precipitation inhibitors has been highlighted for the first time. Copyright © 2018 Elsevier B.V. All rights reserved.

Nondestructive mapping of chemical composition and structural qualities of group III-nitride nanowires using submicron beam synchrotron-based X-ray diffraction

Energy Technology Data Exchange (ETDEWEB)

Bonanno, P.L., E-mail: plb2@njit.edu [Georgia Institute of Technology/GTL, UMI 2958 Georgia Tech-CNRS, 57070 Metz (France); Gautier, S. [LMOPS + UMI: Laboratoire Matériaux Optiques, Photonique et micro-nano Systèmes, UMR CNRS 7132, Université de Metz et SUPELEC, 2 rue E. Belin, 57070 Metz, France, UMI 2958 Georgia Tech-CNRS, 57070 Metz (France); Gmili, Y.El.; Moudakir, T. [UMI 2958 Georgia Tech-CNRS, 57070 Metz (France); Sirenko, A.A. [Department of Physics, New Jersey Institute of Technology, Newark, NJ 07102 (United States); Kazimirov, A. [Cornell High Energy Synchrotron Source (CHESS), Cornell University, Ithaca, NY 14853 (United States); Cai, Z.-H. [Advanced Photon Source, 9700 S. Cass Avenue, Argonne, IL 60439 (United States); Martin, J. [LMOPS + UMI: Laboratoire Matériaux Optiques, Photonique et micro-nano Systèmes, UMR CNRS 7132, Université de Metz et SUPELEC, 2 rue E. Belin, 57070 Metz, France, UMI 2958 Georgia Tech-CNRS, 57070 Metz (France); Goh, W.H. [Georgia Institute of Technology/GTL, UMI 2958 Georgia Tech-CNRS, 57070 Metz (France); Martinez, A.; Ramdane, A.; Le Gratiet, L. [Laboratoire de Photonique et de Nanostructures, UPR CNRS 20, Route de Nozay, 91460 Marcoussis (France); Maloufi, N. [Laboratoire d' Etude des Textures et Application aux Matériaux UMR CNRS 7078 Ile du Saulcy 57045 METZ cedex 1 (France); Assouar, M.B. [Laboratoire de Physique des Milieux Ionisés et Applications, Nancy University, CNRS, BP 239, F-54506 Vandoeuvre-lès-Nancy Cédex (France); Ougazzaden, A. [Georgia Institute of Technology/GTL, UMI 2958 Georgia Tech-CNRS, 57070 Metz (France)

2013-08-31

Submicron beam synchrotron-based X-ray diffraction (XRD) techniques have been developed and used to accurately and nondestructively map chemical composition and material quality of selectively grown group III-nitride nanowires. GaN, AlGaN, and InGaN multi-quantum-well nanowires have been selectively grown on lattice matched and mismatched substrates, and the challenges associated with obtaining and interpreting submicron beam XRD results are addressed and solved. Nanoscale cathodoluminescence is used to examine exciton behavior, and energy-dispersive X-ray spectroscopy is used to verify chemical composition. Scanning transmission electron microscopy is later used to paint a more complete picture. The advantages of submicron beam XRD over other techniques are discussed in the context of this challenging material system. - Highlights: ► We used nano selective area growth to create nanowires of GaN, AlGaN and InGaN/GaN. ► We characterized them by synchrotron-based submicron beam X-ray diffraction (XRD). ► This technique accurately determined chemical and crystallographic properties. ► Challenges of XRD are addressed in the context of this challenging material system. ► Advantages of XRD over other characterization methods are discussed.

Simplification of Water Distribution Network Simulation by Topological Clustering – Investigation of its Potential Use in Copenhagen's Water Supply Monitoring and Contamination Contingency Plans

DEFF Research Database (Denmark)

Kirstein, Jonas Kjeld; Albrechtsen, Hans-Jørgen; Rygaard, Martin

2014-01-01

Topological clustering was investigated to simplify a complex water distribution network of Copenhagen, Denmark, into recogniz- able water movement patterns. This made it possible to assess the general transport of the water and to suggest strategic sampling locations. Through a topological...... the samples’ comparability over time, and locations, where samples represent the distributed and consumed water in the Nørrebro district....

Submicron x-ray diffraction and its applications to problems in materials and environmental science

Science.gov (United States)

Tamura, N.; Celestre, R. S.; MacDowell, A. A.; Padmore, H. A.; Spolenak, R.; Valek, B. C.; Meier Chang, N.; Manceau, A.; Patel, J. R.

2002-03-01

The availability of high brilliance third generation synchrotron sources together with progress in achromatic focusing optics allows us to add submicron spatial resolution to the conventional century-old x-ray diffraction technique. The new capabilities include the possibility to map in situ, grain orientations, crystalline phase distribution, and full strain/stress tensors at a very local level, by combining white and monochromatic x-ray microbeam diffraction. This is particularly relevant for high technology industry where the understanding of material properties at a microstructural level becomes increasingly important. After describing the latest advances in the submicron x-ray diffraction techniques at the Advanced Light Source, we will give some examples of its application in material science for the measurement of strain/stress in metallic thin films and interconnects. Its use in the field of environmental science will also be discussed.

Submicron X-Ray Diffraction and its Applications to Problems in Materials and Environmental Science

Energy Technology Data Exchange (ETDEWEB)

Patel, J. R.

2002-08-16

The availability of high brilliance 3rd generation synchrotron sources together with progress in achromatic focusing optics allow to add submicron spatial resolution to the conventional century-old X-ray diffraction technique. The new capabilities include the possibility to map in-situ, grain orientations, crystalline phase distribution and full strain/stress tensors at a very local level, by combining white and monochromatic X-ray microbeam diffraction. This is particularly relevant for high technology industry where the understanding of material properties at a microstructural level becomes increasingly important. After describing the latest advances in the submicron X-ray diffraction techniques at the ALS, we will give some examples of its application in material science for the measurement of strain/stress in metallic thin films and interconnects. Its use in the field of environmental science will also be discussed.

Submicron X-ray diffraction and its applications to problems in materials and environmental science

Energy Technology Data Exchange (ETDEWEB)

Tamura, N.; Celestre, R.S.; MacDowell, A.A.; Padmore, H.A.; Spolenak, R.; Valek, B.C.; Meier Chang, N.; Manceau, A.; Patel, J.R.

2002-03-26

The availability of high brilliance 3rd generation synchrotron sources together with progress in achromatic focusing optics allow to add submicron spatial resolution to the conventional century-old X-ray diffraction technique. The new capabilities include the possibility to map in-situ, grain orientations, crystalline phase distribution and full strain/stress tensors at a very local level, by combining white and monochromatic X-ray microbeam diffraction. This is particularly relevant for high technology industry where the understanding of material properties at a microstructural level becomes increasingly important. After describing the latest advances in the submicron X-ray diffraction techniques at the ALS, we will give some examples of its application in material science for the measurement of strain/stress in metallic thin films and interconnects. Its use in the field of environmental science will also be discussed.

Role of a Water Network around the Mn4CaO5 Cluster in Photosynthetic Water Oxidation: A Fourier Transform Infrared Spectroscopy and Quantum Mechanics/Molecular Mechanics Calculation Study.

Science.gov (United States)

Nakamura, Shin; Ota, Kai; Shibuya, Yuichi; Noguchi, Takumi

2016-01-26

Photosynthetic water oxidation takes place at the Mn4CaO5 cluster in photosystem II. Around the Mn4CaO5 cluster, a hydrogen bond network is formed by several water molecules, including four water ligands. To clarify the role of this water network in the mechanism of water oxidation, we investigated the effects of the removal of Ca(2+) and substitution with metal ions on the vibrations of water molecules coupled to the Mn4CaO5 cluster by means of Fourier transform infrared (FTIR) difference spectroscopy and quantum mechanics/molecular mechanics (QM/MM) calculations. The OH stretching vibrations of nine water molecules forming a network between D1-D61 and YZ were calculated using the QM/MM method. On the the calculated normal modes, a broad positive feature at 3200-2500 cm(-1) in an S2-minus-S1 FTIR spectrum was attributed to the vibrations of strongly hydrogen-bonded OH bonds of water involving the vibrations of water ligands to a Mn ion and the in-phase coupled vibration of a water network connected to YZ, while bands in the 3700-3500 cm(-1) region were assigned to the coupled vibrations of weakly hydrogen-bonded OH bonds of water. All the water bands were lost upon Ca(2+) depletion and Ba(2+) substitution, which inhibit the S2 → S3 transition, indicating that a solid water network was broken by these treatments. By contrast, Sr(2+) substitution slightly altered the water bands around 3600 cm(-1), reflecting minor modification in water interactions, consistent with the retention of water oxidation activity with a decreased efficiency. These results suggest that the water network around the Mn4CaO5 cluster plays an essential role in the water oxidation mechanism particularly in a concerted process of proton transfer and water insertion during the S2 → S3 transition.

Neurotoxicity of low-dose repeatedly intranasal instillation of nano- and submicron-sized ferric oxide particles in mice

Energy Technology Data Exchange (ETDEWEB)

Wang Bing; Feng Weiyue, E-mail: fengwy@mail.ihep.ac.cn; Zhu Motao; Wang Yun; Wang Meng [Chinese Academy of Sciences, Laboratory for Bio-Environmental Effects of Nanomaterials and Nanosafety and Key Laboratory of Nuclear Analytical Techniques, Institute of High Energy Physics (China); Gu Yiqun [Maternity Hospital of Haidian District (China); Ouyang Hong; Wang Huajian; Li Ming; Zhao Yuliang, E-mail: zhaoyuliang@mail.ihep.ac.cn; Chai Zhifang [Chinese Academy of Sciences, Laboratory for Bio-Environmental Effects of Nanomaterials and Nanosafety and Key Laboratory of Nuclear Analytical Techniques, Institute of High Energy Physics (China); Wang Haifang [Peking University, College of Chemistry and Molecular Engineering (China)

2009-01-15

Olfactory tract has been demonstrated to be an important portal for inhaled solid nanoparticle transportation into the central nervous system (CNS). We have previously demonstrated that intranasally instilled Fe{sub 2}O{sub 3} nanoparticles could transport into the CNS via olfactory pathway. In this study, we investigated the neurotoxicity and size effect of repeatedly low-dose (130 {mu}g) intranasal exposure of nano- and submicron-sized Fe{sub 2}O{sub 3} particles (21 nm and 280 nm) to mice. The biomarkers of oxidative stress, activity of nitric oxide synthases and release of monoamine neurotransmitter in the brain were studied. Our results showed that significant oxidative stress was induced by the two sizes of Fe{sub 2}O{sub 3} particles. The activities of GSH-Px, Cu,Zn-SOD, and cNOS significantly elevated and the total GSH and GSH/GSSG ratio significantly decreased in the olfactory bulb and hippocampus after the nano- and submicron-sized Fe{sub 2}O{sub 3} particle treatment (p < 0.05). The nano-sized Fe{sub 2}O{sub 3} generally induced greater alteration and more significant dose-effect response than the submicron-sized particle did. Some slight perturbation of monoamine neurotransmitters were found in the hippocampus after exposure to the two sizes of Fe{sub 2}O{sub 3} particle. The TEM image showed that some ultrastructural alterations in nerve cells, including neurodendron degeneration, membranous structure disruption and lysosome increase in the olfactory bulb, slight dilation in the rough endoplasmic reticulum and lysosome increase in the hippocampus were induced by the nano-sized Fe{sub 2}O{sub 3} treatment. In contrast, in the submicron-sized Fe{sub 2}O{sub 3} treated mice, slightly swollen mitochondria and some vacuoles were observed in the olfactory bulb and hippocampus, respectively. These results indicate that intranasal exposure of Fe{sub 2}O{sub 3} nanoparticles could induce more severe oxidative stress and nerve cell damage in the brain than the

Mountain pine beetle-killed lodgepole pine for the production of submicron lignocellulose fibrils

Science.gov (United States)

Ingrid Hoeger; Rolland Gleisner; Jose Negron; Orlando J. Rojas; J. Y. Zhu

2014-01-01

The elevated levels of tree mortality attributed to mountain pine beetle (MPB) (Dendroctonus ponderosae Hopkins) in western North American forests create forest management challenges. This investigation introduces the production of submicron or nanometer lignocellulose fibrils for value-added materials from the widely available resource represented by dead pines after...

Breaking Frontiers: Submicron Structures in Physics and Biology - 52 Zakopane School of Physics

International Nuclear Information System (INIS)

2008-01-01

The 52 Zakopane School of Physics held in Zakopane from 19 to 24 May 2008. The main task of the symposium was to present the newest results of research in field of submicron structures in physics, biology and medicine. Some new technologies as well as their applications are also presented

Breaking Frontiers: Submicron Structures in Physics and Biology - 52 Zakopane School of Physics

Energy Technology Data Exchange (ETDEWEB)

NONE

2008-07-01

The 52 Zakopane School of Physics held in Zakopane from 19 to 24 May 2008. The main task of the symposium was to present the newest results of research in field of submicron structures in physics, biology and medicine. Some new technologies as well as their applications are also presented.

Grain orientation and strain measurements in sub-micron wide passivated individual aluminum test structures

International Nuclear Information System (INIS)

Tamura, N.; Valek, B.C.; Spolenak, R.; MacDowell, A.A.; Celestre, R.S.; Padmore, H.A.; Brown, W.L.; Marieb, T.; Bravman, J.C.; Batterman, B.W.; Patel, J.R.

2001-01-01

An X-ray microdiffraction dedicated beamline, combining white and monochromatic beam capabilities, has been built at the Advanced Light Source. The purpose of this beamline is to address the myriad of problems in Materials Science and Physics that require submicron x-ray beams for structural characterization. Many such problems are found in the general area of thin films and nano-materials. For instance, the ability to characterize the orientation and strain state in individual grains of thin films allows us to measure structural changes at a very local level. These microstructural changes are influenced heavily by such parameters as deposition conditions and subsequent treatment. The accurate measurement of strain gradients at the micron and sub-micron level finds many applications ranging from the strain state under nano-indenters to gradients at crack tips. Undoubtedly many other applications will unfold in the future as we gain experience with the capabilities and limitations of this instrument. We have applied this technique to measure grain orientation and residual stress in single grains of pure Al interconnect lines and preliminary results on post-electromigration test experiments are presented. It is shown that measurements with this instrument can be used to resolve the complete stress tensor (6 components) in a submicron volume inside a single grain of Al under a passivation layer with an overall precision of about 20 MPa. The microstructure of passivated lines appears to be complex, with grains divided into identifiable subgrains and noticeable local variations of both tensile/compressive and shear stresses within single grains

Where Water is Oxidized to Dioxygen: Structure of the Photosynthetic Mn4Ca Cluster from X-ray Spectroscopy

Energy Technology Data Exchange (ETDEWEB)

Yano, Junko; Yano, Junko; Yachandra, Vittal K.

2007-10-24

Light-driven oxidation of water to dioxygen in plants, algae and cyanobacteria iscatalyzed within photosystem II (PS II) by a Mn4Ca cluster. Although the cluster has been studied by many different methods, the structure and the mechanism have remained elusive. X-ray absorption and emission spectroscopy and EXAFS studies have been particularly useful in probing the electronic and geometric structure, and the mechanism of the water oxidation reaction. Recent progress, reviewed here, includes polarized X-ray absorption spectroscopy measurements of PS II single crystals. Analysis of those results has constrained the Mn4Ca cluster geometry to a setof three similar high-resolution structures. The structure of the cluster from the present study is unlike either the 3.0 or 3.5 Angstrom-resolution X-ray structures or other previously proposed models. The differences between the models derived from X-rayspectroscopy and crystallography are predominantly because of damage to the Mn4Ca cluster by X-rays under the conditions used for structure determination by X-ray crystallography. X-ray spectroscopy studies are also used for studying the changes in the structure of the Mn4Ca catalytic center as it cycles through the five intermediate states known as the Si-states (i=0-4). The electronic structure of the Mn4Ca cluster has been studied more recently using resonant inelastic X-ray scattering spectroscopy (RIXS), in addition to the earlier X-ray absorption and emission spectroscopy methods. These studies are revealing that the assignment of formaloxidation states is overly simplistic. A more accurate description should consider the charge density on the Mn atoms that includes the covalency of the bonds and delocalization of the charge over the cluster. The geometric and electronic structure of the Mn4Ca cluster in the S-states derived from X-ray spectroscopy are leading to a detailed understanding of the mechanism of the O-O bond formation during the photosynthetic water

Submicron and ultrafine grained hardmetals for microdrills and metal cutting inserts

International Nuclear Information System (INIS)

Gille, G.; Szesny, B.; Dreyer, K.; Berg, H. van den; Schidt, J.; Gestrich, T.; Leitner, G.

2001-01-01

Although round tools as carbide drills and mills are dominating by far the application of submicron and ultrafine hardmetals the consumption for PCB microdrills had the strongest growth rate over the last decade. This paper deals with the latest developments of ultrafine hardmetals and their application for PCB microdrills and metal cutting inserts. Based on optimized processing and properties such as hardness, hot hardness, toughness, strength and wear resistance a new generation of microdrills is presented. In particular the failure probability of the microdrills could be considerably reduced and the number of drilling strokes was nearly doubled. Combining improved pressing behavior with proper doping and optimized processing new applications of submicron and ultrafine hardmetals could be obtained by using complex shaped metal cutting inserts. Apart from these application examples the paper gives some insight into fundamental investigations an sintering and properties of ultrafine hardmetals and shows in particular the influence of milling, doping and sintering an the properties of ultrafine hardmetals. The paper also presents a new ultrafine WC grade showing a 0.1 μm WC intercept of a sintered WC - 10 wt % Co structure and a hardness of HV 30 = 2050 for a 1 wt % mixed VC/Cr 3 C 2 doping. (author)

Design and characterization of submicron formulation for a poorly soluble drug: the effect of Vitamin E TPGS and other solubilizers on skin permeability enhancement.

Science.gov (United States)

Ghosh, Indrajit; Michniak-Kohn, Bozena

2012-09-15

In transdermal drug delivery systems (TDDS), it is a challenge to achieve stable and prolonged high permeation rates across the skin since the concentrations of the drug dissolved in the matrix have to be high in order to maintain zero order release kinetics. Several attempts have been reported to improve the permeability of poorly soluble drug compounds using supersaturated systems, however, due to thermodynamic challenges, there was a high tendency for the drug to nucleate immediately after formulating or even during storage. The present study focuses on the efficiency of drug crystals at the submicron/nano range in presence of different solubilizers to improve the permeation rate. Effect of several solubilizers, e.g. Pluronic F-127, Vitamin E TPGS, propylene glycol were studied on the submicron suspension systems of ibuprofen as a model drug. Various stabilizers such as hydroxylpropyl methylcellulose (HPMC) and polyvinylpyrrolidone (PVP) were examined to evaluate their crystal inhibitory effects on particle growth of the drug compound at submicron range. The overall permeation enhancement process through the skin seems to be influenced by the presence of solubilizers and also the presence of submicron drug crystal. The most promising stable formulation was developed with Vitamin E TPGS+HPMC submicron suspension, which produced higher permeation rate compared to other vehicles. Copyright © 2012 Elsevier B.V. All rights reserved.

Submicron InP DHBT technology for high-speed high-swing mixed-signal ICs

DEFF Research Database (Denmark)

Godin, Jean; Nodjiadjim, V.; Riet, Muriel

2008-01-01

We report on the development of a submicron InP DHBT technology, optimized for the fabrication of 50-GHz-clock mixed signal ICs. In-depth study of device geometry and structure has allowed to get the needed performances and yield. Special attention has been paid to critical thermal behavior. Vari...... applications of interest....

Country clustering applied to the water and sanitation sector: a new tool with potential applications in research and policy.

Science.gov (United States)

Onda, Kyle; Crocker, Jonny; Kayser, Georgia Lyn; Bartram, Jamie

2014-03-01

The fields of global health and international development commonly cluster countries by geography and income to target resources and describe progress. For any given sector of interest, a range of relevant indicators can serve as a more appropriate basis for classification. We create a new typology of country clusters specific to the water and sanitation (WatSan) sector based on similarities across multiple WatSan-related indicators. After a literature review and consultation with experts in the WatSan sector, nine indicators were selected. Indicator selection was based on relevance to and suggested influence on national water and sanitation service delivery, and to maximize data availability across as many countries as possible. A hierarchical clustering method and a gap statistic analysis were used to group countries into a natural number of relevant clusters. Two stages of clustering resulted in five clusters, representing 156 countries or 6.75 billion people. The five clusters were not well explained by income or geography, and were distinct from existing country clusters used in international development. Analysis of these five clusters revealed that they were more compact and well separated than United Nations and World Bank country clusters. This analysis and resulting country typology suggest that previous geography- or income-based country groupings can be improved upon for applications in the WatSan sector by utilizing globally available WatSan-related indicators. Potential applications include guiding and discussing research, informing policy, improving resource targeting, describing sector progress, and identifying critical knowledge gaps in the WatSan sector. Copyright © 2013 Elsevier GmbH. All rights reserved.

SiO2/ZnO Composite Hollow Sub-Micron Fibers: Fabrication from Facile Single Capillary Electrospinning and Their Photoluminescence Properties

Directory of Open Access Journals (Sweden)

Guanying Song

2017-02-01

Full Text Available In this work, SiO2/ZnO composite hollow sub-micron fibers were fabricated by a facile single capillary electrospinning technique followed by calcination, using tetraethyl orthosilicate (TEOS, polyvinylpyrrolidone (PVP and ZnO nanoparticles as raw materials. The characterization results of the scanning electron microscopy (SEM, transmission electron microscopy (TEM, X-ray diffraction (XRD and Fourier transform infrared spectroscopy (FT-IR spectra indicated that the asprepared composite hollow fibers consisted of amorphous SiO2 and hexagonal wurtzite ZnO. The products revealed uniform tubular structure with outer diameters of 400–500 nm and wall thickness of 50–60 nm. The gases generated and the directional escaped mechanism was proposed to illustrate the formation of SiO2/ZnO composite hollow sub-micron fibers. Furthermore, a broad blue emission band was observed in the photoluminescence (PL of SiO2/ZnO composite hollow sub-micron fibers, exhibiting great potential applications as blue light-emitting candidate materials.

Revealing isomerism in sodium-water clusters: Photoionization spectra of Na(H2O)n (n = 2-90)

Science.gov (United States)

Dierking, Christoph W.; Zurheide, Florian; Zeuch, Thomas; Med, Jakub; Parez, Stanislav; Slavíček, Petr

2017-06-01

Soft ionization of sodium tagged polar clusters is increasingly used as a powerful technique for sizing and characterization of small aerosols with possible application, e.g., in atmospheric chemistry or combustion science. Understanding the structure and photoionization of the sodium doped clusters is critical for such applications. In this work, we report on measurements of photoionization spectra for sodium doped water clusters containing 2-90 water molecules. While most of the previous studies focused on the ionization threshold of the Na(H2O)n clusters, we provide for the first time full photoionization spectra, including the high-energy region, which are used as reference for a comparison with theory. As reported in previous work, we have seen an initial drop of the appearance ionization energy with cluster size to values of about 3.2 eV for n electron cloud. The appearance ionization energy is determined by isomers with fully solvated sodium and a highly delocalized electron cloud, while both fully and incompletely solvated isomers with localized electron clouds can contribute to the high energy part of the photoionization spectrum. Simulations at elevated temperatures show an increased abundance of isomers with low ionization energies, an entropic effect enabling size selective infrared action spectroscopy, based on near threshold photoionization of Na(H2O)n clusters. In addition, simulations of the sodium pick-up process were carried out to study the gradual formation of the hydrated electron which is the basis of the sodium-tagging sizing.

From collisions to clusters

DEFF Research Database (Denmark)

Loukonen, Ville; Bork, Nicolai; Vehkamaki, Hanna

2014-01-01

-principles molecular dynamics collision simulations of (sulphuric acid)1(water)0, 1 + (dimethylamine) → (sulphuric acid)1(dimethylamine)1(water)0, 1 cluster formation processes. The simulations indicate that the sticking factor in the collisions is unity: the interaction between the molecules is strong enough...... control. As a consequence, the clusters show very dynamic ion pair structure, which differs from both the static structure optimisation calculations and the equilibrium first-principles molecular dynamics simulations. In some of the simulation runs, water mediates the proton transfer by acting as a proton...... to overcome the possible initial non-optimal collision orientations. No post-collisional cluster break up is observed. The reasons for the efficient clustering are (i) the proton transfer reaction which takes place in each of the collision simulations and (ii) the subsequent competition over the proton...

Infrared spectroscopy of water clusters isolated in methane matrices: Effects of isotope substitution and annealing

International Nuclear Information System (INIS)

Yamakawa, Koichiro; Ehara, Namika; Ozawa, Nozomi; Arakawa, Ichiro

2016-01-01

Using infrared-active solvents of CH_4 and CD_4 for matrix isolation, we measured infrared spectra of H_2O and D_2O clusters at 7 K. The solute-concentration dependence of the spectrum of H_2O clusters in a CH_4 matrix was investigated and was used for the peak assignment. Annealing procedures were found to promote the size growth of water clusters in methane matrices for all the combinations of (H_2O, CH_4), (H_2O, CD_4), (D_2O, CH_4), and (D_2O, CD_4). We also monitored the ν_3 absorption due to methane to find the annealing-induced structural change only of solid CH_4. The matrix effects on the vibrations of the clusters are discussed on the basis of “T_c plots”, where their frequencies are plotted as a function of the square root of the matrix critical temperature, T_c. The obtained plots assure the validity of the assignment of the cluster peaks.

Multiobjective optimization of cluster-scale urban water systems investigating alternative water sources and level of decentralization

Science.gov (United States)

Newman, J. P.; Dandy, G. C.; Maier, H. R.

2014-10-01

In many regions, conventional water supplies are unable to meet projected consumer demand. Consequently, interest has arisen in integrated urban water systems, which involve the reclamation or harvesting of alternative, localized water sources. However, this makes the planning and design of water infrastructure more difficult, as multiple objectives need to be considered, water sources need to be selected from a number of alternatives, and end uses of these sources need to be specified. In addition, the scale at which each treatment, collection, and distribution network should operate needs to be investigated. In order to deal with this complexity, a framework for planning and designing water infrastructure taking into account integrated urban water management principles is presented in this paper and applied to a rural greenfield development. Various options for water supply, and the scale at which they operate were investigated in order to determine the life-cycle trade-offs between water savings, cost, and GHG emissions as calculated from models calibrated using Australian data. The decision space includes the choice of water sources, storage tanks, treatment facilities, and pipes for water conveyance. For each water system analyzed, infrastructure components were sized using multiobjective genetic algorithms. The results indicate that local water sources are competitive in terms of cost and GHG emissions, and can reduce demand on the potable system by as much as 54%. Economies of scale in treatment dominated the diseconomies of scale in collection and distribution of water. Therefore, water systems that connect large clusters of households tend to be more cost efficient and have lower GHG emissions. In addition, water systems that recycle wastewater tended to perform better than systems that captured roof-runoff. Through these results, the framework was shown to be effective at identifying near optimal trade-offs between competing objectives, thereby enabling

Limitation and suppression of hot electron fluctuations in submicron semiconductor structures

International Nuclear Information System (INIS)

Kochelap, V.A.; Zahleniuk, N.A.; Sokolov, V.N.

1992-09-01

We present theoretical investigations of fluctuations of hot electrons in submicron active regions, where the dimensions 2 d of the region is comparable to the electron energy relaxation length L ε . The new physical phenomenon is reported; the fluctuations depend on the sample thickness, with 2d ε a suppression of fluctuations arises in the range of fluctuation frequencies ω much less than T -1 ε , T ε is the electron energy relaxation time. (author). 12 refs, 7 figs

Dynamics of water clusters confined in proteins: a molecular dynamics simulation study of interfacial waters in a dimeric hemoglobin.

Science.gov (United States)

Gnanasekaran, Ramachandran; Xu, Yao; Leitner, David M

2010-12-23

Water confined in proteins exhibits dynamics distinct from the dynamics of water in the bulk or near the surface of a biomolecule. We examine the water dynamics at the interface of the two globules of the homodimeric hemoglobin from Scapharca inaequivalvis (HbI) by molecular dynamics (MD) simulations, with focus on water-protein hydrogen bond lifetimes and rotational anisotropy of the interfacial waters. We find that relaxation of the waters at the interface of both deoxy- and oxy-HbI, which contain a cluster of 17 and 11 interfacial waters, respectively, is well described by stretched exponentials with exponents from 0.1 to 0.6 and relaxation times of tens to thousands of picoseconds. The interfacial water molecules of oxy-HbI exhibit slower rotational relaxation and hydrogen bond rearrangement than those of deoxy-HbI, consistent with an allosteric transition from unliganded to liganded conformers involving the expulsion of several water molecules from the interface. Though the interfacial waters are translationally and rotationally static on the picosecond time scale, they contribute to fast communication between the globules via vibrations. We find that the interfacial waters enhance vibrational energy transport across the interface by ≈10%.

Velocity overshoot decay mechanisms in compound semiconductor field-effect transistors with a submicron characteristic length

International Nuclear Information System (INIS)

Jyegal, Jang

2015-01-01

Velocity overshoot is a critically important nonstationary effect utilized for the enhanced performance of submicron field-effect devices fabricated with high-electron-mobility compound semiconductors. However, the physical mechanisms of velocity overshoot decay dynamics in the devices are not known in detail. Therefore, a numerical analysis is conducted typically for a submicron GaAs metal-semiconductor field-effect transistor in order to elucidate the physical mechanisms. It is found that there exist three different mechanisms, depending on device bias conditions. Specifically, at large drain biases corresponding to the saturation drain current (dc) region, the velocity overshoot suddenly begins to drop very sensitively due to the onset of a rapid decrease of the momentum relaxation time, not the mobility, arising from the effect of velocity-randomizing intervalley scattering. It then continues to drop rapidly and decays completely by severe mobility reduction due to intervalley scattering. On the other hand, at small drain biases corresponding to the linear dc region, the velocity overshoot suddenly begins to drop very sensitively due to the onset of a rapid increase of thermal energy diffusion by electrons in the channel of the gate. It then continues to drop rapidly for a certain channel distance due to the increasing thermal energy diffusion effect, and later completely decays by a sharply decreasing electric field. Moreover, at drain biases close to a dc saturation voltage, the mechanism is a mixture of the above two bias conditions. It is suggested that a large secondary-valley energy separation is essential to increase the performance of submicron devices

Short range investigation of sub-micron zirconia particles

Energy Technology Data Exchange (ETDEWEB)

Caracoche, M C; Martinez, J A [Departamento de Fisica, IFLP, Facultad de Ciencias Exactas, CICPBA, Universidad Nacional de La Plata (Argentina); Rivas, P C [IFLP-CONICET, Facultad de Ciencias Agrarias y Forestales, Universidad Nacional de La Plata (Argentina); Bondioli, F; Cannillo, V [Dipartimento di Ingegniria dei Materiali e dell' Ambiente, Facolta di Ingegneria, Universita di Modena e Reggio Emilia (Italy); Ferrari, A M, E-mail: cristina@fisica.unlp.edu.a [Dipartimento di Scienza a Metodi dell' Ingegneria, Universita di Modena e Reggio Emilia (Italy)

2009-05-01

The Perturbed Angular Correlations technique was used to determine the configurations around Zirconium ions and their thermal behavior in non-aggregated sub-micron zirconia spherical particles. Three residues containing- Zr surroundings were determined for the non-crystalline starting particles, which were identified under the assumption of a certain chemical reactions sequence during synthesis. While the one made up mainly by hydroxyl groups was common to both samples, the two involving mainly organic residues were particle size dependent. Upon crystallization, both samples stabilized in the t'- and t- tetragonal forms and the Xc-cubic form but their amounts and temperatures of appearance were different. On heating, the structure of the smaller particles became gradually monoclinic achieving total degradation upon the subsequent cooling to RT.

Hydration structure and dynamics of a hydroxide ion in water clusters of varying size and temperature: Quantum chemical and ab initio molecular dynamics studies

International Nuclear Information System (INIS)

Bankura, Arindam; Chandra, Amalendu

2012-01-01

Highlights: ► A theoretical study of hydroxide ion-water clusters is carried for varying cluster size and temperature. ► The structures of OH − (H 2 O) n are found out through quantum chemical calculations for n = 4, 8, 16 and 20. ► The finite temperature behavior of the clusters is studied through ab initio dynamical simulations. ► The spectral features of OH modes (deuterated) and their dependence on hydrogen bonding states of water are discussed. ► The mechanism and kinetics of proton transfer processes in these anionic clusters are also investigated. - Abstract: We have investigated the hydration structure and dynamics of OH − (H 2 O) n clusters (n = 4, 8, 16 and 20) by means of quantum chemical and ab initio molecular dynamics calculations. Quantum chemical calculations reveal that the solvation structure of the hydroxide ion transforms from three and four-coordinated surface states to five-coordinated interior state with increase in cluster size. Several other isomeric structures with energies not very different from the most stable isomer are also found. Ab initio simulations show that the most probable configurations at higher temperatures need not be the lowest energy isomeric structure. The rates of proton transfer in these clusters are found to be slower than that in bulk water. The vibrational spectral calculations reveal distinct features for free OH (deuterated) stretch modes of water in different hydrogen bonding states. Effects of temperature on the structural and dynamical properties are also investigated for the largest cluster considered here.

Application of Fuzzy Clustering in Modeling of a Water Hydraulics System

DEFF Research Database (Denmark)

Zhou, Jianjun; Kroszynski, Uri

2000-01-01

This article presents a case study of applying fuzzy modeling techniques for a water hydraulics system. The obtained model is intended to provide a basis for model-based control of the system. Fuzzy clustering is used for classifying measured input-output data points into partitions. The fuzzy...... model is extracted from the obtained partitions. The identified model has been evaluated by comparing measurements with simulation results. The evaluation shows that the identified model is capable of describing the system dynamics over a reasonably wide frequency range....

Facile synthesis and stable cycling ability of hollow submicron silicon oxide–carbon composite anode material for Li-ion battery

Energy Technology Data Exchange (ETDEWEB)

Kim, Joong-Yeon; Nguyen, Dan Thien [Department of Fine Chemical Engineering & Applied Chemistry, Chungnam National University, Daejeon 305-764 (Korea, Republic of); Kang, Joon-Sup [Department of Energy Science and Technology, Chungnam National University, Daejeon 305-764 (Korea, Republic of); Song, Seung-Wan, E-mail: swsong@cnu.ac.kr [Department of Fine Chemical Engineering & Applied Chemistry, Chungnam National University, Daejeon 305-764 (Korea, Republic of); Department of Energy Science and Technology, Chungnam National University, Daejeon 305-764 (Korea, Republic of)

2015-06-05

Highlights: • Hollow submicron SiO{sub 2}–carbon composite material was synthesized using Si{sup 4+}-citrate chelation. • Composite material possessed a homogeneous distribution of SiO{sub 2} and carbon. • Composite electrode delivered ⩾600 mAh/g with a stable cycling stability. • This materials design and synthesis provides a useful platform for scalable production. - Abstract: Advanced SiO{sub 2}–carbon composite anode active material for lithium-ion battery has been synthesized through a simple chelation of silicon cation with citrate in a glyme-based solvent. The resultant composite material demonstrates a homogeneous distribution of constituents over the submicron particles and a unique hollow spherical microstructure, which provides an enhanced electrical conductivity and better accommodation of volume change of silicon during electrochemical charge–discharge cycling, respectively. As a result, the composite electrode exhibits a high cycling stability delivering the capacity retention of 91% at the 100th cycle and discharge capacities of 662–602 mAh/g and coulombic efficiencies of 99.8%. This material synthesis is scalable and cost-effective in preparing various submicron or micron composite electrode materials.

Submicron polycaprolactone particles as a carrier for imaging contrast agent for in vitro applications.

Science.gov (United States)

Iqbal, Muhammad; Robin, Sophie; Humbert, Philippe; Viennet, Céline; Agusti, Geraldine; Fessi, Hatem; Elaissari, Abdelhamid

2015-12-01

Fluorescent materials have recently attracted considerable attention due to their unique properties and high performance as imaging agent in biomedical fields. Different imaging agents have been encapsulated in order to restrict its delivery to a specific area. In this study, a fluorescent contrast agent was encapsulated for in vitro application by polycaprolactone (PCL) polymer. The encapsulation was performed using modified double emulsion solvent evaporation technique with sonication. Fluorescent nanoparticles (20 nm) were incorporated in the inner aqueous phase of double emulsion. A number of samples were fabricated using different concentrations of fluorescent contrast agent. The contrast agent-containing submicron particle was characterized by a zetasizer for average particle size, SEM and TEM for morphology observations and fluorescence spectrophotometer for encapsulation efficiency. Moreover, contrast agent distribution in the PCL matrix was determined by confocal microscopy. The incorporation of contrast agent in different concentrations did not affect the physicochemical properties of PCL particles and the average size of encapsulated particles was found to be in the submicron range. Copyright © 2015 Elsevier B.V. All rights reserved.

Efflux Performance of Submicron Particles in Packed Bed under Periodic Pressure Conditions; Shuki atsuho ni yoru juten sonai sabumikuron biryushi no ryushutsu tokusei

Energy Technology Data Exchange (ETDEWEB)

Ping, Z; Iritani, E; Murase, T [Nagaya Univ. Nagoya (Japan). Department of Chemical Engineering

1997-09-01

Permeation experiments of ultrapure water were conducted under periodic pressure conditions using a packed bed obtained by dispersing submicron particles of polymethyl methacrylate (PMMA) uniformly into a packed bed of particles of White Alundum. It is clearly demonstrated that washing performance under periodic pressure conditions where the permeation pressure is applied periodically is improved dramatically, compared with that under constant pressure conditions. It is also shown that the effect of periodic pressure operation is especially noticeable in the initial stage of the pressurizing period, and that a pressurizing time smaller than 2 min is very effective under conditions examined in this study. 4 figs.

Number Size Distributions and Seasonality of Submicron Particles in Europe 2008–2009

Czech Academy of Sciences Publication Activity Database

Asmi, A.; Wiedensohler, A.; Laj, P.; Fjaeraa, A.-M.; Sellegri, K.; Birmili, W.; Weingartner, E.; Baltensperger, U.; Ždímal, Vladimír; Zíková, Naděžda; Putaud, J.-P.; Marioni, A.; Tunved, P.; Hansson, H.-C.; Fiebig, M.; Kivekäs, N.; Lihavainen, H.; Asmi, E.; Ulevicius, V.; Aalto, P.P.; Swietlicki, E.; Kristensson, E.; Mihalopoulos, N.; Kalivitis, N.; Kalapov, I.; Kiss, G.; de Leeuw, G.; Henzig, B.; Harrison, R. M.; Beddows, D.; O´Dowd, C.; Jennings, S.G.; Flentje, H.; Weinhold, K.; Meinhardt, F.; Ries, L.; Kulmala, M.

2011-01-01

Roč. 11, - (2011), s. 5505-5538 ISSN 1680-7316 EU Projects: European Commission(XE) RII3-CT-2006-026140; European Commission(XE) 36833; European Commission(IT) Ev-K2-CNR Grant - others:AFCE(FI) 1118615 Program:FP6 Institutional research plan: CEZ:AV0Z40720504 Keywords : aerosol particle number * aerosol concentrations * european submicron Subject RIV: CF - Physical ; Theoretical Chemistry Impact factor: 5.520, year: 2011

Chemical Heterogeneity of a Large Cluster IDP: Clues to its Formation History Using X-ray Fluorescence Mapping and XANES Spectroscopy

Science.gov (United States)

Wirick, S.; Flynn, G. J.; Sutton, S.; Zolensky, M. E.

2013-01-01

Chondritic porous IDPs may be among the most primitive objects found in our solar system [1]. They consist of many micron to submicron minerals, glasses and carbonaceous matter [2,3,4,5,6,7] with > 10(exp 4) grains in a 10 micron cluster [8]. Speculation on the environment where these fine grained, porous IDPs formed varies with possible sources being presolar dusty plasma clouds, protostellar condensation, solar asteroids or comets [4,6,9]. Also, fine grained dust forms in our solar system today [10,11]. Isotopic anomalies in some particles in IDPs suggest an interstellar source[4,7,12]. IDPs contain relic particles left from the dusty plasma that existed before the protostellar disk formed and other grains in the IDPs formed later after the cold dense nebula cloud collapsed to form our protostar and other grains formed more recently. Fe and CR XANES spectroscopy is used here to investigate the oxygen environment in a large (>50 10 micron or larger sub-units) IDP. Conclusions: Analyzing large (>50 10 micron or larger sub-units) CP IDPs gives one a view on the environments where these fine dust grains formed which is different from that found by only analyzing the small, 10 micron IDPs. As with cluster IDP L2008#5 [3], L2009R2 cluster #13 appears to be an aggregate of grains that sample a diversity of solar and perhaps presolar environments. Sub-micron, grain by grain measurement of trace element contents and elemental oxidation states determined by XANES spectroscopy offers the possibility of understanding the environments in which these grains formed when compared to standard spectra. By comparing thermodynamic modeling of condensates with analytical data an understanding of transport mechanisms operating in the early solar system may be attained.

A continuous flow micro filtration device for plasma/blood separation using submicron vertical pillar gap structures

International Nuclear Information System (INIS)

Kang, Tae Goo; Ji, Hongmiao; Lim, Pei Yi; Chen, Yu; Yoon, Yong-Jin

2014-01-01

This work demonstrates a continuous flow plasma/blood separator using a vertical submicron pillar gap structure. The working principle of the proposed separator is based on size exclusion of cells through cross-flow filtration, in which only plasma is allowed to pass through submicron vertical pillars located tangential to the main flow path of the blood sample. The maximum filtration efficiency of 99.9% was recorded with a plasma collection rate of 0.67 µl min −1 for an input blood flow rate of 12.5 µl min −1 . The hemolysis phenomenon was observed for an input blood flow rate above 30 µl min −1 . Based on the experimental results, we can conclude that the proposed device shows potential for the application of on-chip plasma/blood separation as a part of integrated point-of-care (POC) diagnostics systems. (technical note)

Submicron-sized aerosol and radon progeny measurements in an uranium mine

International Nuclear Information System (INIS)

Boulaud, D.; Chouard, J.C.

1992-01-01

Submicron-sized aerosol was studied in an uranium mine using an Electrical Aerosol Analyzer and a Differential Mobility Particle Sizer. In addition radon progeny particle size distributions were measured using a prototype instrument developed by us (SDI 2000). With cascade impactor the number weighted mean electrical mobility diameters and the geometric standard deviations ranged respectively from 0.05 to 0.1 μm and 1.8 to 2. The gross alpha activity weighted mean thermodynamic diameters ranged typically from 0.1 to 0.2 μm. 6 refs., 3 figs

Mobility of Hematite Submicron Particles in Water Solutions of Sugar

International Nuclear Information System (INIS)

Fornal, P.; Stanek, J.

2008-01-01

The mobility of the 100 nm Fe 2 O 3 particles in dense water solutions of sugar (sucrose) was determined from the analysis of the resonance absorption line shape of the Moessbauer spectra recorded in the -5 o C to 40 o C temperature range for different sugar concentrations. The discrepancy between the experimental data and the prediction of the classical theory of Brownian movement are interpreted in the term of the short observation time and the interaction between the solid particles in fluids, which extends in water up to 300 nm. The sedimentation process in the studied colloids was observed. (authors)

Synthesis and characterization of hollow α-Fe2O3 sub-micron spheres prepared by sol–gel

International Nuclear Information System (INIS)

León, Lizbet; Bustamante, Angel; Osorio, Ana; Olarte, G. S.; Santos Valladares, Luis De Los; Barnes, Crispin H. W.; Majima, Yutaka

2011-01-01

In this work we report the preparation of magnetic hematite hollow sub-micron spheres (α-Fe 2 O 3 ) by colloidal suspensions of ferric nitrate nine-hydrate (Fe(NO 3 ) 3 ·9H 2 O) particles in citric acid solution by following the sol–gel method. After the gel formation, the samples were annealed at different temperatures in an oxidizing atmosphere. Annealing at 180°C resulted in an amorphous phase, without iron oxide formation. Annealing at 250°C resulted in coexisting phases of hematite, maghemite and magnetite, whereas at 400°C, only hematite and maghemite were found. Pure hematite hollow sub-micron spheres with porous shells were formed after annealing at 600°C. The characterization was performed by X-ray diffraction (XRD), Mössbauer spectroscopy (MS) and scanning electron microscopy (SEM).

Preliminary investigations of the chemical speciation of plutonium in natural waters of the northeastern and southeastern United States

Energy Technology Data Exchange (ETDEWEB)

Alberts, J. J.; Wahlgren, M. A.; Nelson, D. M.; Rowland, R. E.

1975-01-01

Preliminary investigation indicated that the concentration of fallout /sup 240/Pu in lake water from the northeast differs from that in the southeast or from snowmelt and that the submicron size distribution and charge distributions appear different for the various water samples.

Effect of Water Clustering on the Activity of Candida antarctica Lipase B in Organic Medium

DEFF Research Database (Denmark)

Banik, Sindrila Dutta; Nordblad, Mathias; Woodley, John M.

2017-01-01

The effect of initial water activity of MTBE (methyl tert-butyl ether) medium on CALB (Candida antarctica lipase B) catalyzed esterification reaction is investigated using experimental methods and classical molecular dynamics (MD) simulations. The experimental kinetic studies show that the initial...... reaction rate of CALB-catalyzed esterification reaction between butyric acid and ethanol decreases with increasing initial water activity of the medium. The highest rate of esterification is observed at the lowest water activity studied. MD simulations were performed to gain a molecular insight...... on the effect of initial water activity on the rate of CALB-catalyzed reaction. Our results show that hydration has an insignificant effect on the structure and flexibility of CALB. Rather, it appears that water molecules bind to certain regions ("hot spots") on the CALB surface and form clusters. The size...

Using a novel spectroscopic reflectometer to optimize a radiation-hardened submicron silicon-on-sapphire CMOS process

International Nuclear Information System (INIS)

Do, N.T.; Zawaideh, E.; Vu, T.Q.; Warren, G.; Mead, D.; Do, N.T.; Li, G.P.; Tsai, C.S.

1999-01-01

A radiation-hardened sub-micron silicon-on-sapphire CMOS process is monitored and optimized using a novel optical technique based on spectroscopic reflectometry. Quantitative measurements of the crystal quality, surface roughness, and device radiation hardness show excellent correlation between this technique and the Atomic Force Microscopy. (authors)

WO3 nanoflakes decorated with CuO clusters for enhanced photoelectrochemical water splitting

Directory of Open Access Journals (Sweden)

Chongwu Wang

2018-04-01

Full Text Available The low quantum efficiency arising from poor charges transfer and insufficient light absorption is one of the critical challenges toward achieving highly efficient water splitting in photoelectrochemical cells. Three dimensions (3D structures and heterojunctions have received intensive research interests recent years due to their excellent ability to separate photo-generated charges as well as the enhanced light harvesting property. Herein, 3D CuO/WO3 structure was fabricated through a facile solvothermal method followed by chemical bath deposition. The loading of CuO clusters on WO3 nanoflake arrays results in a much improved photocurrent density compared with that of pristine WO3 nanoflake arrays, which reaches 1.8 mA/cm2 at 1.23 V vs. the reversible hydrogen electrode. The electrochemical impedance spectroscopy measurement demonstrates that the improved performance of CuO/WO3 electrode is attributed to the accelerated charge transfer kinetics as a result of the desirable band alignment in CuO/WO3 heterojunction. This work demonstrates a facile strategy to construct superior WO3 electrode, which will ultimately allow for efficient storage of solar energy into hydrogen. Keywords: Photoelectrochemistry, Water splitting, Tungsten trioxide photoanode, CuO clusters, Heterojunction

Fabrication of submicron conducting and chemically functionalized structures from poly(3-octylthiophene) by an electron beam

International Nuclear Information System (INIS)

Cai, S.X.; Kanskar, M.; Nabity, J.C.; Keana, J.F.W.; Wybourne, M.N.

1992-01-01

The authors present a novel method of using an electron beam to both functionalize and cross-link poly (3-octylthiophene) (P3OT) in a single step to produce submicron scale polymer structures carrying functionalized groups. P3OT is shown to be a negative electron-beam resist with a sensitivity of 15-30 μC cm -2 .The electrical conductivity of doped P3OT wire structures was measured at room temperature and was found to be in the range 4.0-5.9 Ω -1 cm -1 . Electron-beam exposure of P3OT films containing 7 wt % of N-hydroxysuccinimide (NHS) functionalized perfluorophenyl azide 2 resulted in the incorporation of the NHS functional groups in the polymer, as well as cross-linking. The functionalized submicron structures were found to be weakly fluorescent under fluorescein excitation (450-490 nm), but after treatment with a solution of 5-(aminoacetamido)fluorescein in ethanol the structures became strongly fluorescent. 27 refs., 3 figs

"Divide-and-conquer" semiclassical molecular dynamics: An application to water clusters

Science.gov (United States)

Di Liberto, Giovanni; Conte, Riccardo; Ceotto, Michele

2018-03-01

We present an investigation of vibrational features in water clusters performed by means of our recently established divide-and-conquer semiclassical approach [M. Ceotto, G. Di Liberto, and R. Conte, Phys. Rev. Lett. 119, 010401 (2017)]. This technique allows us to simulate quantum vibrational spectra of high-dimensional systems starting from full-dimensional classical trajectories and projection of the semiclassical propagator onto a set of lower dimensional subspaces. The potential energy surface employed is a many-body representation up to three-body terms, in which monomers and two-body interactions are described by the high level Wang-Huang-Braams-Bowman (WHBB) water potential, while, for three-body interactions, calculations adopt a fast permutationally invariant ab initio surface at the same level of theory of the WHBB 3-body potential. Applications range from the water dimer up to the water decamer, a system made of 84 vibrational degrees of freedom. Results are generally in agreement with previous variational estimates in the literature. This is particularly true for the bending and the high-frequency stretching motions, while estimates of modes strongly influenced by hydrogen bonding are red shifted, in a few instances even substantially, as a consequence of the dynamical and global picture provided by the semiclassical approach.

Sub-micron silicon nitride waveguide fabrication using conventional optical lithography.

Science.gov (United States)

Huang, Yuewang; Zhao, Qiancheng; Kamyab, Lobna; Rostami, Ali; Capolino, Filippo; Boyraz, Ozdal

2015-03-09

We demonstrate a novel technique to fabricate sub-micron silicon nitride waveguides using conventional contact lithography with MEMS-grade photomasks. Potassium hydroxide anisotropic etching of silicon facilitates line reduction and roughness smoothing and is key to the technique. The fabricated waveguides is measured to have a propagation loss of 0.8dB/cm and nonlinear coefficient of γ = 0.3/W/m. A low anomalous dispersion of <100ps/nm/km is also predicted. This type of waveguide is highly suitable for nonlinear optics. The channels naturally formed on top of the waveguide also make it promising for plasmonics and quantum efficiency enhancement in sensing applications.

Microscopic methods in analysis of submicron phospholipid dispersions

Directory of Open Access Journals (Sweden)

Płaczek Marcin

2016-03-01

Full Text Available Microscopy belongs to the group of tests, used in pharmaceutical technology, that despite the lapse of time and the development of new analytical methods, still remain irreplaceable for the characterization of dispersed drug dosage forms (e.g., suspensions and emulsions. To obtain complete description of a specific drug formulation, such as parenteral colloidal products, a combination of different microscopic techniques is sometimes required. Electron microscopy methods are the most useful ones; however, even such basic methods as optical microscopy may be helpful for determination of some properties of a sample. The publication explicates the most popular microscopical techniques used nowadays for characterization of the morphology of nanoparticles suspended in pharmaceutical formulations; ad vantages and disadvantages of these methods are also discussed. Parenteral submicron formulations containing lecithin or a particular phospholipid were chosen as examples.

Preparation and characterization of SiO2-coated submicron-sized L10 Fe-Pt particles

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Yoshiaki Hayashi

2018-05-01

Full Text Available The development of magnets with higher performance is attracting increasing interest. The optimization of their microstructure is essential to enhance their properties, and a microstructure comprising magnetically isolated hard magnetic grains of a single-domain size has been proposed as an ideal structure for enhancing the coercivity of magnets. To obtain magnets with an ideal structure, we consider the fabrication of magnets by an approach based on core/shell nanoparticles with a hard magnetic core and a non-magnetic shell. In this study, to obtain particles for our proposed approach, we attempted to fabricate L10 Fe-Pt/SiO2-core/shell particles with submicron-sized cores less than the critical single-domain size. The fabrication of such core/shell particles was confirmed from morphology observations and XRD analysis of the particles. Although the formation of more desirable core/shell particles with submicron-sized single-crystal cores in the single-domain size range was not achieved, the fabricated core/shell particles showed a high coercivity of 25 kOe.

Modelling of passive heating for replication of sub-micron patterns in optical disk substrates

Energy Technology Data Exchange (ETDEWEB)

Kim, Youngmin; Bae, Jaecheol; Kim, Hongmin; Kang, Shinill [School of Mechanical Engineering, Yonsei University, 134 Shinchon-dong, Seodaemoon-ku, Seoul (Korea, Republic of)

2004-05-07

The transcribability of pit or land groove structures in replicating an optical disk substrate greatly affects the performance of a high-density optical disk. However, a solidified layer generated during the polymer filling worsens transcribability because the solidified layer prevents the polymer melt from filling the sub-micron patterns. Therefore, the development of the solidified layer during the filling stage of injection moulding must be delayed. For this delay, passive heating through an insulation layer has been used. In the present study, to examine the development of the solidified layer, delayed by passive heating, the flow of the polymer melt with passive heating was analysed. Passive heating delayed markedly the development of the solidified layer, reduced the viscosity of the polymer melt, and increased the fluidity of the polymer melt in the vicinity of the stamper surface with the sub-micron patterns. As a result, we predict that passive heating can improve the transcribability of an optical disk substrate. To verify our prediction, we fabricated an optical disk substrate by using passive heating of a mould and measured the transcribability of an optical disk substrate.

Modelling of passive heating for replication of sub-micron patterns in optical disk substrates

International Nuclear Information System (INIS)

Kim, Youngmin; Bae, Jaecheol; Kim, Hongmin; Kang, Shinill

2004-01-01

The transcribability of pit or land groove structures in replicating an optical disk substrate greatly affects the performance of a high-density optical disk. However, a solidified layer generated during the polymer filling worsens transcribability because the solidified layer prevents the polymer melt from filling the sub-micron patterns. Therefore, the development of the solidified layer during the filling stage of injection moulding must be delayed. For this delay, passive heating through an insulation layer has been used. In the present study, to examine the development of the solidified layer, delayed by passive heating, the flow of the polymer melt with passive heating was analysed. Passive heating delayed markedly the development of the solidified layer, reduced the viscosity of the polymer melt, and increased the fluidity of the polymer melt in the vicinity of the stamper surface with the sub-micron patterns. As a result, we predict that passive heating can improve the transcribability of an optical disk substrate. To verify our prediction, we fabricated an optical disk substrate by using passive heating of a mould and measured the transcribability of an optical disk substrate

Pulsed EPR for studying silver clusters

International Nuclear Information System (INIS)

Michalik, J.; Wasowicz, T.; Sadlo, J.; Reijerse, E.J.; Kevan, L.

1996-01-01

The cationic silver clusters of different nuclearity have been produced by radiolysis of zeolite A and SAPO molecular sieves containing Ag + as exchangeable cations. The pulsed EPR spectroscopy has been applied for studying the local environment of silver cluster in order to understand the mechanism of cluster formation and stabilization. the electron spin echo modulation (ESEM) results on Ag 6 n+ cluster in dehydration zeolite A indicate that the hexameric silver is stabilized only in sodalite cages which are surrounded by α-cages containing no water molecules. Trimeric silver clusters formed in hydrated A zeolites strongly interact with water, thus the paramagnetic center can be considered as a cluster-water adduct. In SAPO-molecular sieves, silver clusters are formed only in the presence of adsorbed alcohol molecules. From ESEM it is determined that Ag 4 n+ in SAPO-42 is stabilized in α cages, where it is directly coordinated by two methanol molecules. Dimeric silver, Ag 2 + in SAPO-5 and SAPO-11 is located in 6-ring channels and interacts with three CH 3 OH molecules, each in different 10 ring or 12 ring channels. The differences of Ag 2 + stability in SAPO-5 and SAPO-11 are also discussed. (Author)

Electron-induced chemistry in microhydrated sulfuric acid clusters

Science.gov (United States)

Lengyel, Jozef; Pysanenko, Andriy; Fárník, Michal

2017-11-01

We investigate the mixed sulfuric acid-water clusters in a molecular beam experiment with electron attachment and negative ion mass spectrometry and complement the experiment by density functional theory (DFT) calculations. The microhydration of (H2SO4)m(H2O)n clusters is controlled by the expansion conditions, and the electron attachment yields the main cluster ion series (H2SO4)m(H2O)nHSO4- and (H2O)nH2SO4-. The mass spectra provide an experimental evidence for the onset of the ionic dissociation of sulfuric acid and ion-pair (HSO4- ṡ ṡ ṡ H3O+) formation in the neutral H2SO4(H2O)n clusters with n ≥ 5 water molecules, in excellent agreement with the theoretical predictions. In the clusters with two sulfuric acid molecules (H2SO4)2(H2O)n this process starts as early as n ≥ 2 water molecules. The (H2SO4)m(H2O)nHSO4- clusters are formed after the dissociative electron attachment to the clusters containing the (HSO4- ṡ ṡ ṡ H3O+) ion-pair structure, which leads to the electron recombination with the H3O+ moiety generating H2O molecule and the H-atom dissociation from the cluster. The (H2O)nH2SO4- cluster ions point to an efficient caging of the H atom by the surrounding water molecules. The electron-energy dependencies exhibit an efficient electron attachment at low electron energies below 3 eV, and no resonances above this energy, for all the measured mass peaks. This shows that in the atmospheric chemistry only the low-energy electrons can be efficiently captured by the sulfuric acid-water clusters and converted into the negative ions. Possible atmospheric consequences of the acidic dissociation in the clusters and the electron attachment to the sulfuric acid-water aerosols are discussed.

Water-soluble phosphine-protected Au9 clusters: Electronic structures and nuclearity conversion via phase transfer

Science.gov (United States)

Yao, Hiroshi; Tsubota, Shuhei

2017-08-01

In this article, isolation, exploration of electronic structures, and nuclearity conversion of water-soluble triphenylphosphine monosulfonate (TPPS)-protected nonagold (Au9) clusters are outlined. The Au9 clusters are obtained by the reduction of solutions containing TPPS and HAuCl4 and subsequent electrophoretic fractionation. Mass spectrometry and elemental analysis reveal the formation of [Au9(TPPS)8]5- nonagold cluster. UV-vis absorption and magnetic circular dichroism (MCD) spectra of aqueous [Au9(TPPS)8]5- are quite similar to those of [Au9(PPh3)8]3+ in organic solvent, so the solution-phase structures are likely similar for both systems. Simultaneous deconvolution analysis of absorption and MCD spectra demonstrates the presence of some weak electronic transitions that are essentially unresolved in the UV-vis absorption. Quantum chemical calculations for a model compound [Au9(pH3)8]3+ show that the possible (solution-phase) skeletal structure of the nonagold cluster has D2h core symmetry rather than C4-symmetrical centered crown conformation, which is known as the crystal form of the Au9 compound. Moreover, we find a new nuclearity conversion route from Au9 to Au8; that is, phase transfer of aqueous [Au9(TPPS)8]5- into chloroform using tetraoctylammonium bromide yields [Au8(TPPS)8]6- clusters in the absence of excess phosphine.

Resonant ion-dip infrared spectroscopy of benzene-(water)n-(methanol)m clusters with n+m=4, 5

International Nuclear Information System (INIS)

Hagemeister, F.C.; Gruenloh, C.J.; Zwier, T.S.

1998-01-01

Resonant two-photon ionization and resonant ion-dip infrared (RIDIR) spectra of benzene-(water) n -(methanol) m clusters (hereafter shortened to BW n M m ) have been recorded for a total of seven clusters with n+m=4 and 5. The infrared spectra in the OH and CH stretch regions show absorptions characteristic of H-bonded W n M m clusters which are bound to benzene by a π H-bond involving a dangling OH on the W n M m sub-unit. Density functional theory (DFT) calculations identify a number of conformational isomers in the n+m=4 series which meet the general criteria imposed by the experimental spectra. The structures, binding energies, harmonic vibrational frequencies, and infrared intensities for these isomers have been calculated for comparison with experiment. Based on the calculations, tentative assignments of several of the observed species are given. The calculations uncover the fact that complexation of benzene to the cyclic water tetramer imposes much the same perturbations on the cycle as substitution of methanol for water. In particular, the single-donor OH stretch spectra of W n M m and BW n+1 M m-1 are calculated to be virtually identical to one another. The comparison of experiment and theory for this series of cyclic structures is used to assess the strengths and limitations of the calculations at the DFT Becke3LYP/6-31+G * level of theory. (Copyright (c) 1998 Elsevier Science B.V., Amsterdam. All rights reserved.)

Measurement of initial clustering on the radon decay product 218Po

International Nuclear Information System (INIS)

Strydom, R.

1989-01-01

The formation of water clusters on 218 Po ions is studied. The formation of the water clusters is discussed in the light of the classical theory of clustering, the clustering theory of Hawrynski and a kinetic model of clustering. The design of a specialized electric mobility spectrometer to measure the electric mobilities of the water clusters at various humidity levels is discussed. From the mobilities the radii of, and a number of water molecules in, the clusters are calculated using kinetic gas theory. The determinations were done for humidity levels between 0,16 and 96% relative humidity, and the results compared with the theoretical predictions. It was found that the classical theory underestimates the sizes of the clusters and the theory of Hawrynski overestimates the cluster sizes. It is concluded that the spectrometer is capable of high resolution measurement of the electric mobility of the small clusters. The underlying result of the clustering theories is that stable clusters with particular radii are formed at each humidity level. 91 refs., 70 figs., 11 tabs

Promotion and provision of drinking water in schools for overweight prevention: randomized, controlled cluster trial.

Science.gov (United States)

Muckelbauer, Rebecca; Libuda, Lars; Clausen, Kerstin; Toschke, André Michael; Reinehr, Thomas; Kersting, Mathilde

2009-04-01

The study tested whether a combined environmental and educational intervention solely promoting water consumption was effective in preventing overweight among children in elementary school. The participants in this randomized, controlled cluster trial were second- and third-graders from 32 elementary schools in socially deprived areas of 2 German cities. Water fountains were installed and teachers presented 4 prepared classroom lessons in the intervention group schools (N = 17) to promote water consumption. Control group schools (N = 15) did not receive any intervention. The prevalence of overweight (defined according to the International Obesity Task Force criteria), BMI SD scores, and beverage consumption (in glasses per day; 1 glass was defined as 200 mL) self-reported in 24-hour recall questionnaires, were determined before (baseline) and after the intervention. In addition, the water flow of the fountains was measured during the intervention period of 1 school year (August 2006 to June 2007). Data on 2950 children (intervention group: N = 1641; control group: N = 1309; age, mean +/- SD: 8.3 +/- 0.7 years) were analyzed. After the intervention, the risk of overweight was reduced by 31% in the intervention group, compared with the control group, with adjustment for baseline prevalence of overweight and clustering according to school. Changes in BMI SD scores did not differ between the intervention group and the control group. Water consumption after the intervention was 1.1 glasses per day greater in the intervention group. No intervention effect on juice and soft drink consumption was found. Daily water flow of the fountains indicated lasting use during the entire intervention period, but to varying extent. Our environmental and educational, school-based intervention proved to be effective in the prevention of overweight among children in elementary school, even in a population from socially deprived areas.

Hierarchical TiO{sub 2} submicron-sized spheres for enhanced power conversion efficiency in dye-sensitized solar cells

Energy Technology Data Exchange (ETDEWEB)

Wang, Hao [Hubei Collaborative Innovation Centre for Advanced Organic Chemical Materials and Ministry of Education Key Laboratory for the Green Preparation and Application of Functional Materials, Hubei University, Wuhan 430062 (China); State Key Laboratory of Solid Lubrication, Lanzhou Institute of Chemical Physics, Chinese Academy of Sciences, Lanzhou 730000 (China); Guo, Zhiguang, E-mail: zguo@licp.cas.cn [Hubei Collaborative Innovation Centre for Advanced Organic Chemical Materials and Ministry of Education Key Laboratory for the Green Preparation and Application of Functional Materials, Hubei University, Wuhan 430062 (China); State Key Laboratory of Solid Lubrication, Lanzhou Institute of Chemical Physics, Chinese Academy of Sciences, Lanzhou 730000 (China)

2015-10-15

Hierarchical TiO{sub 2} submicron-sized sphere scattering layer, with relatively large surface area and effective light scattering, shows enhanced power conversion efficiency in dye-sensitized solar cells. - Highlights: • Hierarchical TiO{sub 2} submicron-sized spheres (TiO{sub 2} HSSs) with diameters of 400–600 nm were synthesized. • The HSSs composed of nanoparticles of ∼14 nm have a relatively large surface area of ∼35 m{sup 2}/g. • DSC exhibited the highest cell efficiency (6.23%) compared with ones with pure P25 (5.50%) or HSS (2.00%) photoanodes. - Abstract: Hierarchical TiO{sub 2} submicron-sized spheres (TiO{sub 2} HSSs) with diameters of 400–600 nm were synthesized by a facile one-step solvothermal method in ethanol solvent. The HSSs composed of nanoparticles of ∼14 nm have a relatively large surface area of ∼35 m{sup 2}/g. When applied as the scattering overlayer in dye-sensitized solar cells (DSCs), such TiO{sub 2} HSSs effectively improved light harvesting and led to the increase of photocurrent in DSCs. Furthermore, bilayer-structured photoanode also provided fast electron transportation and long electron lifetime as confirmed by electrochemical impedance spectra. As a result, DSC based on P25 nanoparticle underlayer and HSS-2 overlayer exhibited the highest cell efficiency (6.23%) compared with ones with pure P25 (5.50%) or HSS-2 (2.00%) photoanodes.

Kinetics of CO Oxidation over Unloaded and Pd-Loaded α-Fe2O3 Spherical Submicron Powder Catalysts: Photoacoustic Investigations at Low Pressure

Directory of Open Access Journals (Sweden)

Joong-Seok Roh

2018-02-01

Full Text Available In this study, α-Fe2O3 spherical particles with an average diameter of approximately 200 nm were synthesized by a solvothermal method for use as both a catalyst and medium for a Pd catalyst. The kinetics of CO oxidation over powders of α-Fe2O3 spherical particles and 14 wt % Pd/α-Fe2O3 spherical particles were measured in a static reactor by using a CO2 laser-based photoacoustic technique. The total pressure was fixed at 40 Torr for the CO/O2/N2 mixture for temperatures in the range of 225–350 °C. The variation in the CO2 photoacoustic signal with the CO2 concentration during CO oxidation was recorded as a function of time, and the CO2 photoacoustic data at the early reaction stage was used to estimate the rates of CO2 formation. Based on plots of ln(rate vs. 1/T, apparent activation energies were calculated as 13.4 kcal/mol for the α-Fe2O3 submicron powder and 13.2 kcal/mol for the 14 wt % Pd/α-Fe2O3 submicron powder. Reaction orders with respect to CO and O2 were determined from the rates measured at various partial pressures of CO and O2 at 350 °C. The zero-order of the reaction with respect to Po2 was observed for CO oxidation over α-Fe2O3 submicron powder, while 0.48 order to Po2 was observed for CO oxidation over Pd/α-Fe2O3 submicron powder. The partial orders with respect to PCO were determined as 0.58 and 0.54 for the α-Fe2O3, and the Pd/α-Fe2O3 submicron powders, respectively. The kinetic results obtained from both catalysts were compared with those for the α-Fe2O3 fine powder catalysts and were used to understand the reaction mechanism.

Spatiotemporal Variation in Composition of Submicron Particles in Santiago Metropolitan Region, Chile

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Matías Tagle

2018-05-01

Full Text Available The chemical composition of submicron particles (aerodynamic diameter Da < 1.0 μm was investigated at three locations in the Santiago Metropolitan Region (SMR, Chile. Measurements campaigns were conducted in winter and spring 2016, at representative sites of a rural, urban, and urban receptor environment. Instrumentation consisted of an optical analyzer to determine Black Carbon (BC and the Aerosol Chemical Speciation Monitor (ACSM to measure concentrations of particulate chloride (Cl−, nitrate (NO3-, sulfate (SO42-, ammonium (NH4+, and non-refractory carbonaceous species (organics. Complementary data, such as ozone concentration and meteorological parameters were obtained from the public air quality network. Results showed that in both the winter and spring seasons the organics predominated in the mass of submicron particles. This fraction was followed in decreasing order by NO3-, NH4+, BC, SO42-, and Cl−. The highest average organics concentrations were measured in winter at the urban (32.2 μg m−3 and urban receptor sites (20.1 μg m−3. In winter, average concentrations of both NO3- and NH4+ were higher at the urban receptor site (12.3 and 4.5 μg m−3, respectively when compared to the urban site (6.4 and 3.1 μg m−3, respectively. In general, all the measured species were present in higher concentrations during winter, excepting SO42-, which was the only one that increased during spring. The transition toward spring was also associated with an acidification of the aerosol at the rural and urban receptor site, while at the urban site the aerosol was observed alkaline. The highest average ozone concentration during both the winter and spring seasons were recorded at the urban receptor site (7.2 and 24.0 ppb, respectively. The study reports data showing that the atmosphere in the SMR has a considerable load of particulate organic compounds, NO3- and NH4+, which are in higher concentrations at urban sites during the winter season

Low-loss, submicron chalcogenide integrated photonics with chlorine plasma etching

Energy Technology Data Exchange (ETDEWEB)

Chiles, Jeff; Malinowski, Marcin; Rao, Ashutosh [CREOL, The College of Optics and Photonics, University of Central Florida, Orlando, Florida 32816 (United States); Novak, Spencer; Richardson, Kathleen [CREOL, The College of Optics and Photonics, University of Central Florida, Orlando, Florida 32816 (United States); Department of Materials Science and Engineering, COMSET, Clemson University, Clemson, South Carolina 29634 (United States); Fathpour, Sasan, E-mail: fathpour@creol.ucf.edu [CREOL, The College of Optics and Photonics, University of Central Florida, Orlando, Florida 32816 (United States); Department of Electrical Engineering and Computer Science, University of Central Florida, Orlando, Florida 32816 (United States)

2015-03-16

A chlorine plasma etching-based method for the fabrication of high-performance chalcogenide-based integrated photonics on silicon substrates is presented. By optimizing the etching conditions, chlorine plasma is employed to produce extremely low-roughness etched sidewalls on waveguides with minimal penalty to propagation loss. Using this fabrication method, microring resonators with record-high intrinsic Q-factors as high as 450 000 and a corresponding propagation loss as low as 0.42 dB/cm are demonstrated in submicron chalcogenide waveguides. Furthermore, the developed chlorine plasma etching process is utilized to demonstrate fiber-to-waveguide grating couplers in chalcogenide photonics with high power coupling efficiency of 37% for transverse-electric polarized modes.

Low-loss, submicron chalcogenide integrated photonics with chlorine plasma etching

International Nuclear Information System (INIS)

Chiles, Jeff; Malinowski, Marcin; Rao, Ashutosh; Novak, Spencer; Richardson, Kathleen; Fathpour, Sasan

2015-01-01

A chlorine plasma etching-based method for the fabrication of high-performance chalcogenide-based integrated photonics on silicon substrates is presented. By optimizing the etching conditions, chlorine plasma is employed to produce extremely low-roughness etched sidewalls on waveguides with minimal penalty to propagation loss. Using this fabrication method, microring resonators with record-high intrinsic Q-factors as high as 450 000 and a corresponding propagation loss as low as 0.42 dB/cm are demonstrated in submicron chalcogenide waveguides. Furthermore, the developed chlorine plasma etching process is utilized to demonstrate fiber-to-waveguide grating couplers in chalcogenide photonics with high power coupling efficiency of 37% for transverse-electric polarized modes

Water-Soluble Phosphine-Protected Au₁₁ Clusters: Synthesis, Electronic Structure, and Chiral Phase Transfer in a Synergistic Fashion.

Science.gov (United States)

Yao, Hiroshi; Iwatsu, Mana

2016-04-05

Synthesis of atomically precise, water-soluble phosphine-protected gold clusters is still currently limited probably due to a stability issue. We here present the synthesis, magic-number isolation, and exploration of the electronic structures as well as the asymmetric conversion of triphenylphosphine monosulfonate (TPPS)-protected gold clusters. Electrospray ionization mass spectrometry and elemental analysis result in the primary formation of Au11(TPPS)9Cl undecagold cluster compound. Magnetic circular dichroism (MCD) spectroscopy clarifies that extremely weak transitions are present in the low-energy region unresolved in the UV-vis absorption, which can be due to the Faraday B-terms based on the magnetically allowed transitions in the cluster. Asymmetric conversion without changing the nuclearity is remarkable by the chiral phase transfer in a synergistic fashion, which yields a rather small anisotropy factor (g-factor) of at most (2.5-7.0) × 10(-5). Quantum chemical calculations for model undecagold cluster compounds are then used to evaluate the optical and chiroptical responses induced by the chiral phase transfer. On this basis, we find that the Au core distortion is ignorable, and the chiral ion-pairing causes a slight increase in the CD response of the Au11 cluster.

Molecular dynamics simulations to examine structure, energetics, and evaporation/condensation dynamics in small charged clusters of water or methanol containing a single monatomic ion.

Science.gov (United States)

Daub, Christopher D; Cann, Natalie M

2012-11-01

We study small clusters of water or methanol containing a single Ca(2+), Na(+), or Cl(-) ion with classical molecular dynamics simulations, using models that incorporate polarizability via the Drude oscillator framework. Evaporation and condensation of solvent from these clusters is examined in two systems, (1) for isolated clusters initially prepared at different temperatures and (2) those with a surrounding inert (Ar) gas of varying temperature. We examine these clusters over a range of sizes, from almost bare ions up to 40 solvent molecules. We report data on the evaporation and condensation of solvent from the clusters and argue that the observed temperature dependence of evaporation in the smallest clusters demonstrates that the presence of heated gas alone cannot, in most cases, solely account for bare ion production in electrospray ionization (ESI), neglecting the key contribution of the electric field. We also present our findings on the structure and energetics of the clusters as a function of size. Our data agree well with the abundant literature on hydrated ion clusters and offer some novel insight into the structure of methanol and ion clusters, especially those with a Cl(-) anion, where we observe the presence of chain-like structures of methanol molecules. Finally, we provide some data on the reparameterizations necessary to simulate ions in methanol using the separately developed Drude oscillator models for methanol and for ions in water.

Electron-induced chemistry in microhydrated sulfuric acid clusters

Directory of Open Access Journals (Sweden)

J. Lengyel

2017-11-01

Full Text Available We investigate the mixed sulfuric acid–water clusters in a molecular beam experiment with electron attachment and negative ion mass spectrometry and complement the experiment by density functional theory (DFT calculations. The microhydration of (H2SO4m(H2On clusters is controlled by the expansion conditions, and the electron attachment yields the main cluster ion series (H2SO4m(H2OnHSO4− and (H2OnH2SO4−. The mass spectra provide an experimental evidence for the onset of the ionic dissociation of sulfuric acid and ion-pair (HSO4−  ⋅  ⋅  ⋅  H3O+ formation in the neutral H2SO4(H2On clusters with n ≥ 5 water molecules, in excellent agreement with the theoretical predictions. In the clusters with two sulfuric acid molecules (H2SO42(H2On this process starts as early as n ≥ 2 water molecules. The (H2SO4m(H2OnHSO4− clusters are formed after the dissociative electron attachment to the clusters containing the (HSO4−  ⋅  ⋅  ⋅  H3O+ ion-pair structure, which leads to the electron recombination with the H3O+ moiety generating H2O molecule and the H-atom dissociation from the cluster. The (H2OnH2SO4− cluster ions point to an efficient caging of the H atom by the surrounding water molecules. The electron-energy dependencies exhibit an efficient electron attachment at low electron energies below 3 eV, and no resonances above this energy, for all the measured mass peaks. This shows that in the atmospheric chemistry only the low-energy electrons can be efficiently captured by the sulfuric acid–water clusters and converted into the negative ions. Possible atmospheric consequences of the acidic dissociation in the clusters and the electron attachment to the sulfuric acid–water aerosols are discussed.

Prospects for sub-micron solid state nuclear magnetic resonance imaging with low-temperature dynamic nuclear polarization.

Science.gov (United States)

Thurber, Kent R; Tycko, Robert

2010-06-14

We evaluate the feasibility of (1)H nuclear magnetic resonance (NMR) imaging with sub-micron voxel dimensions using a combination of low temperatures and dynamic nuclear polarization (DNP). Experiments are performed on nitroxide-doped glycerol-water at 9.4 T and temperatures below 40 K, using a 30 mW tunable microwave source for DNP. With DNP at 7 K, a 0.5 microL sample yields a (1)H NMR signal-to-noise ratio of 770 in two scans with pulsed spin-lock detection and after 80 db signal attenuation. With reasonable extrapolations, we infer that (1)H NMR signals from 1 microm(3) voxel volumes should be readily detectable, and voxels as small as 0.03 microm(3) may eventually be detectable. Through homonuclear decoupling with a frequency-switched Lee-Goldburg spin echo technique, we obtain 830 Hz (1)H NMR linewidths at low temperatures, implying that pulsed field gradients equal to 0.4 G/d or less would be required during spatial encoding dimensions of an imaging sequence, where d is the resolution in each dimension.

X-ray imaging with sub-micron resolution using large-area photon counting detectors Timepix

Science.gov (United States)

Dudak, J.; Karch, J.; Holcova, K.; Zemlicka, J.

2017-12-01

As X-ray micro-CT became a popular tool for scientific purposes a number of commercially available CT systems have emerged on the market. Micro-CT systems have, therefore, become widely accessible and the number of research laboratories using them constantly increases. However, even when CT scans with spatial resolution of several micrometers can be performed routinely, data acquisition with sub-micron precision remains a complicated task. Issues come mostly from prolongation of the scan time inevitably connected with the use of nano-focus X-ray sources. Long exposure time increases the noise level in the CT projections. Furthermore, considering the sub-micron resolution even effects like source-spot drift, rotation stage wobble or thermal expansion become significant and can negatively affect the data. The use of dark-current free photon counting detectors as X-ray cameras for such applications can limit the issue of increased image noise in the data, however the mechanical stability of the whole system still remains a problem and has to be considered. In this work we evaluate the performance of a micro-CT system equipped with nano-focus X-ray tube and a large area photon counting detector Timepix for scans with effective pixel size bellow one micrometer.

A Novel Leakage-tolerant Domino Logic Circuit With Feedback From Footer Transistor In Ultra Deep Submicron CMOS

DEFF Research Database (Denmark)

Moradi, Farshad; Peiravi, Ali; Mahmoodi, Hamid

As the CMOS manufacturing process scales down into the ultra deep sub-micron regime, the leakage current becomes an increasingly more important consideration in VLSI circuit design. In this paper, a high speed and noise immune domino logic circuit is presented which uses the property of the footer...

Refined energetic ordering for sulphate-water (n = 3-6) clusters using high-level electronic structure calculations

Science.gov (United States)

Lambrecht, Daniel S.; McCaslin, Laura; Xantheas, Sotiris S.; Epifanovsky, Evgeny; Head-Gordon, Martin

2012-10-01

This work reports refinements of the energetic ordering of the known low-energy structures of sulphate-water clusters ? (n = 3-6) using high-level electronic structure methods. Coupled cluster singles and doubles with perturbative triples (CCSD(T)) is used in combination with an estimate of basis set effects up to the complete basis set limit using second-order Møller-Plesset theory. Harmonic zero-point energy (ZPE), included at the B3LYP/6-311 + + G(3df,3pd) level, was found to have a significant effect on the energetic ordering. In fact, we show that the energetic ordering is a result of a delicate balance between the electronic and vibrational energies. Limitations of the ZPE calculations, both due to electronic structure errors, and use of the harmonic approximation, probably constitute the largest remaining errors. Due to the often small energy differences between cluster isomers, and the significant role of ZPE, deuteration can alter the relative energies of low-lying structures, and, when it is applied in conjunction with calculated harmonic ZPEs, even alters the global minimum for n = 5. Experiments on deuterated clusters, as well as more sophisticated vibrational calculations, may therefore be quite interesting.

The effects of charge, polymerization, and cluster size on the diffusivity of dissolved Si species in pore water

Science.gov (United States)

Yokoyama, Tadashi; Sakuma, Hiroshi

2018-03-01

Silicon (Si) is the most abundant cation in crustal rocks. The charge and degree of polymerization of dissolved Si significantly change depending on solution pH and Si concentration. We used molecular dynamics (MD) simulations to predict the self-diffusion coefficients of dissolved Si, DSi, for 15 monomeric and polymeric species at ambient temperature. The results showed that DSi decreased with increasing negative charge and increasing degree of polymerization. The relationship between DSi and charge (Z) can be expressed by DSi/10-6 = 2.0 + 9.8e0.47Z, and that between DSi and number of polymerization (NSi) by DSi/10-6 = 9.7/NSi0.56. The results also revealed that multiple Si molecules assembled into a cluster and D decreased as the cluster size increased. Experiments to evaluate the diffusivity of Si in pore water revealed that the diffusion coefficient decreased with increasing Si concentration, a result consistent with the MD simulations. Simulation results can now be used to quantitatively assess water-rock interactions and water-concrete reactions over a wide range of environmentally relevant conditions.

Effect of heat treatment on friction and wear behavior of al-6061 composite reinforced with 10% submicron Al2O3 particles

International Nuclear Information System (INIS)

AlQutub, Amro M

2009-01-01

The present research aims at investigating experimentally the effect of heat treatment on the hardness, wear behavior, and friction properties of 6061 Al composite reinforced with sub-micron Al2O3 (10% vol.) produced by powder metallurgy. Heat treatment of the as-received composite starts by the solution treatment at a temperature of 550 degree C for a period of two hours followed by quenching in chilled water and then age hardening at 175 degree C for different periods. It is illustrated that heat treatment has relatively small effect on the hardness of the composite. This can be attributed to the large interface areas between the matrix and the sub-micron alumina in the composite, which reduces the whole concentration of vacancies in the matrix. The result is reduced efficiency of age hardening. For this reason, wear and friction tests were limited to the heat treated composite with four hours aging only. A pin-on-disc tribometer was used to conduct wear and friction tests against AISI 4140 at room temperature for both as-received composite and heat treated composite (with four hours of aging) for comparison. Wear tests indicate that heat treatment has the advantage of increasing transition load to severe wear by 30% compared to as-received composite. On the other hand, at high loads heat treatment results in larger delaminated flakes on the worn surface, indicating reduced fracture toughness. This, in turn, resulted in higher wear rates compared to the as-received composite. Dry friction coefficient is practically unaffected by the heat treatment. (author)

High Proportions of Sub-micron Particulate Matter in Icelandic Dust Storms in 2015

Science.gov (United States)

Dagsson Waldhauserova, Pavla; Arnalds, Olafur; Olafsson, Haraldur; Magnusdottir, Agnes

2017-04-01

Iceland is extremely active dust region and desert areas of over 44,000 km2 acknowledge Iceland as the largest Arctic and European desert. Frequent dust events, up to 135 dust days annually, transport dust particles far distances towards the Arctic and Europe. Satellite MODIS pictures have revealed dust plumes exceeding 1,000 km. The annual dust deposition was calculated as 40.1 million tons yr-1. Two dust storms were measured in transverse horizontal profile about 90 km far from different dust sources in southwestern Iceland in the summer of 2015. Aerosol monitor DustTrak DRX 8533EP was used to measure PM mass concentrations corresponding to PM1, PM2.5, PM4, PM10 and the total PM15 at several places within the dust plume. Images from camera network operated by the Icelandic Road and Coastal Administration were used to estimate the visibility and spatial extent of measured dust events. A numerical simulation of surface winds was carried out with the numerical model HIRLAM with horizontal resolution of 5 km and used to calculate the total dust flux from the sources. The in situ measurements inside the dust plumes showed that aeolian dust can be very fine. The study highlights that suspended volcanic dust in Iceland causes air pollution with extremely high PM1 concentrations comparable to the polluted urban stations in Europe or Asia rather than reported dust event observations from around the world. The PM1/PM2.5 ratios are generally low during dust storms outside of Iceland, much lower than > 0.9 and PM1/PM10 ratios of 0.34-0.63 found in our study. It shows that Icelandic volcanic dust consists of higher proportion of submicron particles compared to crustal dust. The submicron particles are predicted to travel long distances. Moreover, such submicron particles pose considerable health risk because of high potential for entering the lungs. Icelandic volcanic glass has often fine pipe-vesicular structures known from asbestos and high content of heavy metals. Previous

Aerosols in the tropical and subtropical UT/LS: in-situ measurements of submicron particle abundance and volatility

Directory of Open Access Journals (Sweden)

S. Borrmann

2010-06-01

Full Text Available Processes occurring in the tropical upper troposphere (UT, the Tropical Transition Layer (TTL, and the lower stratosphere (LS are of importance for the global climate, for stratospheric dynamics and air chemistry, and for their influence on the global distribution of water vapour, trace gases and aerosols. In this contribution we present aerosol and trace gas (in-situ measurements from the tropical UT/LS over Southern Brazil, Northern Australia, and West Africa. The instruments were operated on board of the Russian high altitude research aircraft M-55 "Geophysica" and the DLR Falcon-20 during the campaigns TROCCINOX (Araçatuba, Brazil, February 2005, SCOUT-O3 (Darwin, Australia, December 2005, and SCOUT-AMMA (Ouagadougou, Burkina Faso, August 2006. The data cover submicron particle number densities and volatility from the COndensation PArticle counting System (COPAS, as well as relevant trace gases like N₂O, ozone, and CO. We use these trace gas measurements to place the aerosol data into a broader atmospheric context. Also a juxtaposition of the submicron particle data with previous measurements over Costa Rica and other tropical locations between 1999 and 2007 (NASA DC-8 and NASA WB-57F is provided. The submicron particle number densities, as a function of altitude, were found to be remarkably constant in the tropical UT/LS altitude band for the two decades after 1987. Thus, a parameterisation suitable for models can be extracted from these measurements. Compared to the average levels in the period between 1987 and 2007 a slight increase of particle abundances was found for 2005/2006 at altitudes with potential temperatures, Θ, above 430 K. The origins of this increase are unknown except for increases measured during SCOUT-AMMA. Here the eruption of the Soufrière Hills volcano in the Caribbean caused elevated particle mixing ratios. The vertical profiles from Northern hemispheric mid-latitudes between 1999 and 2006 also are

Preparation of submicron-sized spherical particles of gold using laser-induced melting in liquids and low-toxic stabilizing reagent

International Nuclear Information System (INIS)

Tsuji, T.; Higashi, Y.; Tsuji, M.; Ishikawa, Y.; Koshizaki, N.

2015-01-01

Highlights: • Submicron-sized spherical particles of gold were prepared using laser irradiation for the source gold nanoparticles stabilized by NaCl. • The source gold nanoparticles agglomeration was controlled both by the NaCl concentration of and by laser irradiation. • The formation process and the laser-fluence dependence of the particle size of gold nanoparticles in NaCl solutions differs from those in citrate solutions. • We revealed that properties of ligands are significantly important to prepare submicron-sized spherical particles and to control their size. - Abstract: Laser-induced melting in liquids (LIML) was applied to prepare spherical submicron-sized particles of gold (AuSMPs) from gold nanoparticles (AuNPs) stabilized using NaCl. Because undesirable byproducts, which might be generated when organic reagents such as citrate are used as the stabilizing reagent, are not generated from NaCl by laser irradiation, AuSMPs fabricated from AuNPs stabilized by NaCl will be low toxic. The AuSMPs were obtained by laser irradiation of the source AuNPs in NaCl solutions stabilized by NaCl at the proper concentration. Similar to the preparation of AuSMPs from AuNPs stabilized by citrate, the agglomeration of the source AuNPs, which is necessary to obtain AuSMPs, was controlled both by the NaCl concentration and by laser irradiation. However, the formation process and the laser-fluence dependence of the particle size of AuSMPs differed for various NaCl solutions and citrate solutions

Stomatal clustering in Begonia associates with the kinetics of leaf gaseous exchange and influences water use efficiency.

Science.gov (United States)

Papanatsiou, Maria; Amtmann, Anna; Blatt, Michael R

2017-04-01

Stomata are microscopic pores formed by specialized cells in the leaf epidermis and permit gaseous exchange between the interior of the leaf and the atmosphere. Stomata in most plants are separated by at least one epidermal pavement cell and, individually, overlay a single substomatal cavity within the leaf. This spacing is thought to enhance stomatal function. Yet, there are several genera naturally exhibiting stomata in clusters and therefore deviating from the one-cell spacing rule with multiple stomata overlaying a single substomatal cavity. We made use of two Begonia species to investigate whether clustering of stomata alters guard cell dynamics and gas exchange under different light and dark treatments. Begonia plebeja, which forms stomatal clusters, exhibited enhanced kinetics of stomatal conductance and CO2 assimilation upon light stimuli that in turn were translated into greater water use efficiency. Our findings emphasize the importance of spacing in stomatal clusters for gaseous exchange and plant performance under environmentally limited conditions. © The Author 2017. Published by Oxford University Press on behalf of the Society for Experimental Biology.

Clustering mechanism of ethanol-water mixtures investigated with photothermal microfluidic cantilever deflection spectroscopy

Science.gov (United States)

Ghoraishi, M. S.; Hawk, J. E.; Phani, Arindam; Khan, M. F.; Thundat, T.

2016-04-01

The infrared-active (IR) vibrational mode of ethanol (EtOH) associated with the asymmetrical stretching of the C-C-O bond in pico-liter volumes of EtOH-water binary mixtures is calorimetrically measured using photothermal microfluidic cantilever deflection spectroscopy (PMCDS). IR absorption by the confined liquid results in wavelength dependent cantilever deflections, thus providing a complementary response to IR absorption revealing a complex dipole moment dependence on mixture concentration. Solvent-induced blue shifts of the C-C-O asymmetric vibrational stretch for both anti and gauche conformers of EtOH were precisely monitored for EtOH concentrations ranging from 20-100% w/w. Variations in IR absorption peak maxima show an inverse dependence on induced EtOH dipole moment (μ) and is attributed to the complex clustering mechanism of EtOH-water mixtures.

Assessing Many-Body Effects of Water Self-Ions. I: OH-(H2O) n Clusters.

Science.gov (United States)

Egan, Colin K; Paesani, Francesco

2018-04-10

The importance of many-body effects in the hydration of the hydroxide ion (OH - ) is investigated through a systematic analysis of the many-body expansion of the interaction energy carried out at the CCSD(T) level of theory, extrapolated to the complete basis set limit, for the low-lying isomers of OH - (H 2 O) n clusters, with n = 1-5. This is accomplished by partitioning individual fragments extracted from the whole clusters into "groups" that are classified by both the number of OH - and water molecules and the hydrogen bonding connectivity within each fragment. With the aid of the absolutely localized molecular orbital energy decomposition analysis (ALMO-EDA) method, this structure-based partitioning is found to largely correlate with the character of different many-body interactions, such as cooperative and anticooperative hydrogen bonding, within each fragment. This analysis emphasizes the importance of a many-body representation of inductive electrostatics and charge transfer in modeling OH - hydration. Furthermore, the rapid convergence of the many-body expansion of the interaction energy also suggests a rigorous path for the development of analytical potential energy functions capable of describing individual OH - -water many-body terms, with chemical accuracy. Finally, a comparison between the reference CCSD(T) many-body interaction terms with the corresponding values obtained with various exchange-correlation functionals demonstrates that range-separated, dispersion-corrected, hybrid functionals exhibit the highest accuracy, while GGA functionals, with or without dispersion corrections, are inadequate to describe OH - -water interactions.

A Model of Clean Water Supply and Improvement of Enviromental Sanitary Conditions in Residential Clusters in The Mekong Delta, Vietnam

Directory of Open Access Journals (Sweden)

Chi Nguyen Thuy Lan

2015-12-01

Full Text Available In accordance with Decision 99/TTg dated 9/2/1996 and Decision 173/TTg dated 6/11/2001 of the Prime Minister regarding the construction program of residential clusters (residential flood free areas, these residential areas as constructed would be fully equipped with critical infrastructures and services such as water supply and drainage works, toilets with sanitary appropriateness, etc. to ensure environmental sanitary conditions in the residential clusters. However, the actual surveys done in residential clusters in the Mekong Delta show that many arising problems must be addressed to enable the local communities to have better living conditions and ensure the sanitary conditions and environmental safety.

Nanometer, submicron and micron sized aluminum powder prepared by semi-solid mechanical stirring method with addition of ceramic particles

International Nuclear Information System (INIS)

Qin, X.H.; Jiang, D.L.; Dong, S.M.

2004-01-01

Composite powder, which is a mixture of Al/Al 2 O 3 composite particles and nanometer, submicron and micron sized aluminum powder, was prepared by semi-solid mechanical stirring method with addition of Al 2 O 3 ceramic particles. The ceramic particles have an average diameter of 80 μm and a volume fraction of 15% in the slurry. The methods used to measure the size distribution of particles greater than 50 μm and less than 50 μm were sieve analysis and photosedimentation, respectively. The surface morphology and transverse sections of the composite powder of different sizes were examined by scanning electron microscope (SEM), optical microscope and auger electron spectroscopy (AES). The results indicate that the composite powder prepared in present work have a wide size distribution ranging from less than 50-900 μm, and the aluminum particles and Al/Al 2 O 3 composite particles are separated and isolated. The particles greater than 200 μm and less than 50 μm are almost pure aluminum powder. The rate of conversion of ingot aluminum into particles less than 1 μm containing nanometer and submicron sizes is 1.777 wt.% in this work. The aluminum powder of different sizes has different shape and surface morphology, quasi-spherical in shape with rough surface for aluminum particles of micron scale, irregular in shape for aluminum particles of submicron scale, and quite close to a globular or an excellent globular in shape for aluminum particles of nanometer size. On the other hand, the surface of ceramic particle was coated by aluminum particles with maximum thickness less than 10 μm containing nanometer and submicron sizes as a single layer. It is suggested that the surface of ceramic particles can provide more nucleation sites for solidification of liquid aluminum and the nucleation of liquid aluminum can take place readily, grow and adhere on the surface of ceramic particles, although it is poorly wetted by the liquid aluminum and the semi-solid slurry can

Submicron organic aerosol in Tijuana, Mexico, from local and Southern California sources during the CalMex campaign

Science.gov (United States)

Takahama, S.; Johnson, A.; Guzman Morales, J.; Russell, L. M.; Duran, R.; Rodriguez, G.; Zheng, J.; Zhang, R.; Toom-Sauntry, D.; Leaitch, W. R.

2013-05-01

The CalMex campaign was conducted from May 15 to June 30 of 2010 to study the properties and sources of air pollution in Tijuana, Mexico. In this study, submicron organic aerosol mass (OM) composition measured by Fourier Transform Infrared Spectroscopy (FTIR), Aerosol Chemical Speciation Monitor (ACSM), and X-ray spectromicroscopy are combined with statistical analysis and measurements of other atmospheric constituents. The average (±one standard deviation) OM concentration was 3.3 ± 1.7 μg m-3. A large source of submicron aerosol mass at this location was determined to be vehicular sources, which contributed approximately 40% to the submicron OM; largely during weekday mornings. The O/C ratio estimated from ACSM measurements was 0.64 ± 0.19; diurnal variations in this value and the more oxygenated fraction of OM as determined from Positive Matrix Factorization and classification analyses suggest the high degree of oxygenation originates from aged OM, rather than locally-produced secondary organic aerosol. A large contribution of this oxygenated aerosol to Tijuana from various source classes was observed; some fraction of this aerosol mass may be associated with non-refractory components, such as dust or BC. Backtrajectory simulations using the HYSPLIT model suggest that the mean wind vector consistently originated from the northwest region, over the Pacific Ocean and near the Southern California coast, which suggests that the origin of much of the oxygenated organic aerosol observed in Tijuana (as much as 60% of OM) may have been the Southern California Air Basin. The marine aerosol contribution to OM during the period was on average 23 ± 24%, though its contribution varied over synoptic rather than diurnal timescales. BB aerosol contributed 20 ± 20% of the OM during the campaign period, with notable BB events occurring during several weekend evenings.

Synthesis and characterization of hollow {alpha}-Fe{sub 2}O{sub 3} sub-micron spheres prepared by sol-gel

Energy Technology Data Exchange (ETDEWEB)

Leon, Lizbet, E-mail: lizbetlf@gmail.com; Bustamante, Angel; Osorio, Ana; Olarte, G. S. [Universidad Nacional Mayor de San Marcos (Peru); Santos Valladares, Luis De Los, E-mail: ld301@cam.ac.uk; Barnes, Crispin H. W. [University of Cambridge, Cavendish Laboratory (United Kingdom); Majima, Yutaka [Tokyo Institute of Technology, Materials and Structures Laboratory (Japan)

2011-11-15

In this work we report the preparation of magnetic hematite hollow sub-micron spheres ({alpha}-Fe{sub 2}O{sub 3}) by colloidal suspensions of ferric nitrate nine-hydrate (Fe(NO{sub 3}){sub 3}{center_dot}9H{sub 2}O) particles in citric acid solution by following the sol-gel method. After the gel formation, the samples were annealed at different temperatures in an oxidizing atmosphere. Annealing at 180 Degree-Sign C resulted in an amorphous phase, without iron oxide formation. Annealing at 250 Degree-Sign C resulted in coexisting phases of hematite, maghemite and magnetite, whereas at 400 Degree-Sign C, only hematite and maghemite were found. Pure hematite hollow sub-micron spheres with porous shells were formed after annealing at 600 Degree-Sign C. The characterization was performed by X-ray diffraction (XRD), Moessbauer spectroscopy (MS) and scanning electron microscopy (SEM).

The capture of submicron particles by collector plates - Wind-tunnel investigations

International Nuclear Information System (INIS)

Gauthier, Daniel

1971-01-01

The deposition of submicron particles on collector plates parallel to the flow was studied experimentally in a wind-tunnel. The validity of a theoretical model based on brownian diffusion was investigated and its Inadequacies tested. The aerosol sample consisted of uranine particles (mean geometrical radius: about 0. 1 μm). The average flow speeds varied from 1 to 10 m/s and the length of the collector plates between 1 and 10 cm. Results showed that capture was mainly due to diffusion and was in good agreement with the theoretical model; however a noticeable deposit of particles on the front part of the collector edge was observed. Sedimentation was insignificant in almost all the cases. (author) [fr

Bloch-wave engineered submicron-diameter quantum-dot micropillars for cavity QED experiments

DEFF Research Database (Denmark)

Gregersen, Niels; Lermer, Matthias; Reitzenstein, Stephan

2013-01-01

The semiconductor micropillar is attractive for cavity QED experiments. For strong coupling, the figure of merit is proportional to Q/√V, and a design combining a high Q and a low mode volume V is thus desired. However, for the standard submicron diameter design, poor mode matching between the ca...... the cavity and the DBR Bloch mode limits the Q. We present a novel adiabatic design where Bloch-wave engineering is employed to improve the mode matching, allowing the demonstration of a record-high vacuum Rabi splitting of 85 μeV and a Q of 13600 for a 850 nm diameter micropillar....

A 45 nm Stacked CMOS Image Sensor Process Technology for Submicron Pixel.

Science.gov (United States)

Takahashi, Seiji; Huang, Yi-Min; Sze, Jhy-Jyi; Wu, Tung-Ting; Guo, Fu-Sheng; Hsu, Wei-Cheng; Tseng, Tung-Hsiung; Liao, King; Kuo, Chin-Chia; Chen, Tzu-Hsiang; Chiang, Wei-Chieh; Chuang, Chun-Hao; Chou, Keng-Yu; Chung, Chi-Hsien; Chou, Kuo-Yu; Tseng, Chien-Hsien; Wang, Chuan-Joung; Yaung, Dun-Nien

2017-12-05

A submicron pixel's light and dark performance were studied by experiment and simulation. An advanced node technology incorporated with a stacked CMOS image sensor (CIS) is promising in that it may enhance performance. In this work, we demonstrated a low dark current of 3.2 e - /s at 60 °C, an ultra-low read noise of 0.90 e - ·rms, a high full well capacity (FWC) of 4100 e - , and blooming of 0.5% in 0.9 μm pixels with a pixel supply voltage of 2.8 V. In addition, the simulation study result of 0.8 μm pixels is discussed.

On the accuracy of the MB-pol many-body potential for water: Interaction energies, vibrational frequencies, and classical thermodynamic and dynamical properties from clusters to liquid water and ice

Energy Technology Data Exchange (ETDEWEB)

Reddy, Sandeep K.; Straight, Shelby C.; Bajaj, Pushp; Huy Pham, C.; Riera, Marc; Moberg, Daniel R.; Morales, Miguel A.; Knight, Chris; Götz, Andreas W.; Paesani, Francesco

2016-11-21

The MB-pol many-body potential has recently emerged as an accurate molecular model for water simulations from the gas to the condensed phase. In this study, the accuracy of MB-pol is systematically assessed across the three phases of water through extensive comparisons with experimental data and high-level ab initio calculations. Individual many-body contributions to the interaction energies as well as vibrational spectra of water clusters calculated with MB-pol are in excellent agreement with reference data obtained at the coupled cluster level. Several structural, thermodynamic, and dynamical properties of the liquid phase at atmospheric pressure are investigated through classical molecular dynamics simulations as a function of temperature. The structural properties of the liquid phase are in nearly quantitative agreement with X-ray diffraction data available over the temperature range from 268 to 368 K. The analysis of other thermodynamic and dynamical quantities emphasizes the importance of explicitly including nuclear quantum effects in the simulations, especially at low temperature, for a physically correct description of the properties of liquid water. Furthermore, both densities and lattice energies of several ice phases are also correctly reproduced by MB-pol. Following a recent study of DFT models for water, a score is assigned to each computed property, which demonstrates the high and, in many respects, unprecedented accuracy of MB-pol in representing all three phases of water. Published by AIP Publishing.

Nanoscale and submicron fatigue crack growth in nickel microbeams

International Nuclear Information System (INIS)

Yang, Y.; Yao, N.; Imasogie, B.; Soboyejo, W.O.

2007-01-01

This paper presents a novel edge-notched microbeam technique for the study of short fatigue crack growth. The technique is used to study submicron and nanoscale fatigue in LIGA Ni thin films with columnar microstructures. The edge-notched microbeams were fabricated within LIGA Ni thin films, using focused ion beam (FIB) techniques. The microbeams were then cyclically deformed to failure at a stress ratio of 0.1. Different slip-band structures were observed below the nanoscale notches. Cyclic deformation resulted in the formation of primary slip bands below the notch. Subsequent crack growth then occurred by the unzipping of fatigue cracks along intersecting slip bands. The effects of the primary slip bands were idealized using dislocation-based models. These were used to estimate the intrinsic fatigue threshold and the fatigue endurance limit. The estimates from the model are shown to be consistent with experimental data from prior stress-life experiments and current/prior fatigue threshold estimates

Controlled motion of domain walls in submicron amorphous wires

Energy Technology Data Exchange (ETDEWEB)

Ţibu, Mihai; Lostun, Mihaela; Rotărescu, Cristian; Atiţoaie, Alexandru; Lupu, Nicoleta; Óvári, Tibor-Adrian, E-mail: taovari@phys-iasi.ro; Chiriac, Horia [Department of Magnetic Materials and Devices, National Institute of Research and Development for Technical Physics, Iaşi, 700050 (Romania); Allwood, Dan A. [Department of Materials Science and Engineering, University of Sheffield, Sheffield, S1 3JD (United Kingdom)

2016-05-15

Results on the control of the domain wall displacement in cylindrical Fe{sub 77.5}Si{sub 7.5}B{sub 15} amorphous glass-coated submicron wires prepared by rapid quenching from the melt are reported. The control methods have relied on conical notches with various depths, up to a few tens of nm, made in the glass coating and in the metallic nucleus using a focused ion beam (FIB) system, and on the use of small nucleation coils at one of the sample ends in order to apply magnetic field pulses aimed to enhance the nucleation of reverse domains. The notch-based method is used for the first time in the case of cylindrical ultrathin wires. The results show that the most efficient technique of controlling the domain wall motion in this type of samples is the simultaneous use of notches and nucleation coils. Their effect depends on wire diameter, notch depth, its position on the wire length, and characteristics of the applied pulse.

Observations of different core water cluster ions Y-(H2O)n (Y = O2, HOx, NOx, COx) and magic number in atmospheric pressure negative corona discharge mass spectrometry.

Science.gov (United States)

Sekimoto, Kanako; Takayama, Mitsuo

2011-01-01

Reliable mass spectrometry data from large water clusters Y(-)(H(2)O)(n) with various negative core ions Y(-) such as O(2)(-), HO(-), HO(2)(-), NO(2)(-), NO(3)(-), NO(3)(-)(HNO(3))(2), CO(3)(-) and HCO(4)(-) have been obtained using atmospheric pressure negative corona discharge mass spectrometry. All the core Y(-) ions observed were ionic species that play a central role in tropospheric ion chemistry. These mass spectra exhibited discontinuities in ion peak intensity at certain size clusters Y(-)(H(2)O)(m) indicating specific thermochemical stability. Thus, Y(-)(H(2)O)(m) may correspond to the magic number or first hydrated shell in the cluster series Y(-)(H(2)O)(n). The high intensity discontinuity at HO(-)(H(2)O)(3) observed was the first mass spectrometric evidence for the specific stability of HO(-)(H(2)O)(3) as the first hydrated shell which Eigen postulated in 1964. The negative ion water clusters Y(-)(H(2)O)(n) observed in the mass spectra are most likely to be formed via core ion formation in the ambient discharge area (760 torr) and the growth of water clusters by adiabatic expansion in the vacuum region of the mass spectrometers (≈1 torr). The detailed mechanism of the formation of the different core water cluster ions Y(-)(H(2)O)(n) is described. Copyright © 2010 John Wiley & Sons, Ltd.

Assessment of repeatability of composition of perfumed waters by high-performance liquid chromatography combined with numerical data analysis based on cluster analysis (HPLC UV/VIS - CA).

Science.gov (United States)

Ruzik, L; Obarski, N; Papierz, A; Mojski, M

2015-06-01

High-performance liquid chromatography (HPLC) with UV/VIS spectrophotometric detection combined with the chemometric method of cluster analysis (CA) was used for the assessment of repeatability of composition of nine types of perfumed waters. In addition, the chromatographic method of separating components of the perfume waters under analysis was subjected to an optimization procedure. The chromatograms thus obtained were used as sources of data for the chemometric method of cluster analysis (CA). The result was a classification of a set comprising 39 perfumed water samples with a similar composition at a specified level of probability (level of agglomeration). A comparison of the classification with the manufacturer's declarations reveals a good degree of consistency and demonstrates similarity between samples in different classes. A combination of the chromatographic method with cluster analysis (HPLC UV/VIS - CA) makes it possible to quickly assess the repeatability of composition of perfumed waters at selected levels of probability. © 2014 Society of Cosmetic Scientists and the Société Française de Cosmétologie.

A submicron synchrotron X-ray beam generated by capillary optics

International Nuclear Information System (INIS)

Engstroem, P.; Larsson, S.; Rindby, A.; Buttkewitz, A.; Garbe, S.; Gaul, G.; Knoechel, A.; Lechtenberg, F.; Deutsches Elektronen-Synchrotron

1991-01-01

A novel capillary optics technique for focusing synchrotron X-ray beams has been applied in an experiment performed at the DORIS storage ring at HASYLAB. This new technqiue, which utilizes the total reflection properties of X-rays inside small capillaries, has recently been applied to generate microbeams of X-rays, with a beam size down to about 10 μm using conventional X-ray tubes. The result from our recent experiment shows that capillary optics can also be used to generate a submicron beam of X-rays from a synchrotron light source. A description of the capillary unit, and the alignment procedure is given. The influence of the thermal load on the device caused by the intense flux of synchrotron radiation will be discussed. Future perspectives of the capillary techniques as applied to synchrotron radiation will be discussed. (orig.)

Stochastic process variation in deep-submicron CMOS circuits and algorithms

CERN Document Server

Zjajo, Amir

2014-01-01

One of the most notable features of nanometer scale CMOS technology is the increasing magnitude of variability of the key device parameters affecting performance of integrated circuits. The growth of variability can be attributed to multiple factors, including the difficulty of manufacturing control, the emergence of new systematic variation-generating mechanisms, and most importantly, the increase in atomic-scale randomness, where device operation must be described as a stochastic process. In addition to wide-sense stationary stochastic device variability and temperature variation, existence of non-stationary stochastic electrical noise associated with fundamental processes in integrated-circuit devices represents an elementary limit on the performance of electronic circuits. In an attempt to address these issues, Stochastic Process Variation in Deep-Submicron CMOS: Circuits and Algorithms offers unique combination of mathematical treatment of random process variation, electrical noise and temperature and ne...

New constraints on deformation processes in serpentinite from sub-micron Raman Spectroscopy and TEM

Science.gov (United States)

Smith, S. A. F.; Tarling, M.; Rooney, J. S.; Gordon, K. C.; Viti, C.

2017-12-01

Extensive work has been performed to characterize the mineralogical and mechanical properties of the various serpentine minerals (i.e. antigorite, lizardite, chrysotile, polyhedral and polygonal serpentine). However, correct identification of serpentine minerals is often difficult or impossible using conventional analytical techniques such as optical- and SEM-based microscopy, X-ray diffraction and infrared spectroscopy. Transmission Electron Microscopy (TEM) is the best analytical technique to identify the serpentine minerals, but TEM requires complex sample preparation and typically results in very small analysis areas. Sub-micron confocal Raman spectroscopy mapping of polished thin sections provides a quick and relatively inexpensive way of unambiguously distinguishing the main serpentine minerals within their in-situ microstructural context. The combination of high spatial resolution (with a diffraction-limited system, 366 nm), large-area coverage (up to hundreds of microns in each dimension) and ability to map directly on thin sections allows intricate fault rock textures to be imaged at a sample-scale, which can then form the target of more focused TEM work. The potential of sub-micron Raman Spectroscopy + TEM is illustrated by examining sub-micron-scale mineral intergrowths and deformation textures in scaly serpentinites (e.g. dissolution seams, mineral growth in pressure shadows), serpentinite crack-seal veins and polished fault slip surfaces from a serpentinite-bearing mélange in New Zealand. The microstructural information provided by these techniques has yielded new insights into coseismic dehydration and amorphization processes and the interplay between creep and localised rupture in serpentinite shear zones.

Study of lead phytoavailability for atmospheric industrial micronic and sub-micronic particles in relation with lead speciation

Energy Technology Data Exchange (ETDEWEB)

Uzu, G. [EcoLab UMR 5245 CNRS-INPT-UPS, ENSAT BP 32607 Auzeville Tolosane, 31326 Castanet Tolosan (France)], E-mail: gaelle.uzu@ensat.fr; Sobanska, S. [LASIR UMR 8516, Universite des Sciences et Technologies de Lille, Batiment C5, 59655 Villeneuve d' Ascq Cedex (France)], E-mail: Sophie.Sobanska@univ-lille1.fr; Aliouane, Y. [EcoLab UMR 5245 CNRS-INPT-UPS, ENSAT BP 32607 Auzeville Tolosane, 31326 Castanet Tolosan (France); Pradere, P. [Chemical Metal Treatment Company, STCM, 30-32 chemin de Fondeyre, 31200 Toulouse (France)], E-mail: p.pradere@stc-metaux.com; Dumat, C. [EcoLab UMR 5245 CNRS-INPT-UPS, ENSAT BP 32607 Auzeville Tolosane, 31326 Castanet Tolosan (France)], E-mail: camille.dumat@ensat.fr

2009-04-15

Particles from channelled emissions of a battery recycling facility were size-segregated and investigated to correlate their speciation and morphology with their transfer towards lettuce. Microculture experiments carried out with various calcareous soils spiked with micronic and sub-micronic particles (1650 {+-} 20 mg Pb kg{sup -1}) highlighted a greater transfer in soils mixed with the finest particles. According to XRD and Raman spectroscopy results, the two fractions presented differences in the amount of minor lead compounds like carbonates, but their speciation was quite similar, in decreasing order of abundance: PbS, PbSO{sub 4}, PbSO{sub 4}.PbO, {alpha}-PbO and Pb{sup 0}. Morphology investigations revealed that PM{sub 2.5} (i.e. Particulate Matter 2.5 composed of particles suspended in air with aerodynamic diameters of 2.5 {mu}m or less) contained many Pb nanoballs and nanocrystals which could influence lead availability. The soil-plant transfer of lead was mainly influenced by size and was very well estimated by 0.01 M CaCl{sub 2} extraction. - The soil-lettuce lead transfer from atmospheric industrial sub-micronic and micronic particles depends on particle size.

Effective immobilization of glucose oxidase on chitosan submicron particles from gladius of Todarodes pacificus for glucose sensing.

Science.gov (United States)

Anusha, J R; Fleming, Albin T; Kim, Hee-Je; Kim, Byung Chul; Yu, Kook-Hyun; Raj, C Justin

2015-08-01

An effective enzymatic glucose biosensor was developed by immobilizing glucose oxidase on chitosan submicron particles synthesized from the gladius of Todarodes pacificus (GCSP). The chemically synthesized chitosan from gladius was pulverized to submicron particles by ball milling technique, which was further characterized and compared with the standard chitosan (SCS). The degree of deacetylation of GCSP was determined using FTIR spectroscopy which was comparable to the value of standard chitosan. The glucose oxidase (GOx) was immobilized over GCSP on porous zinc oxide/platinum nanoparticle (ZnO/Pt) based electrode. The morphological and structural properties of the electrodes were analyzed using scanning electron microscopy and X-ray diffraction analysis. The glucose sensing behavior of electrode was estimated using electrochemical analysis and showed an excellent analytical performance. The electrode ZnO/Pt/GCSP conjugated with GOx displayed high sensitivity (88.76 μA mM(-1) cm(-2)) with low detection limit in short response time. In addition, the very low value of Michaelis-Menten constant for GCSP based electrode contributes a better affinity of the electrode surface towards glucose oxidase. Copyright © 2015 Elsevier B.V. All rights reserved.

Study of lead phytoavailability for atmospheric industrial micronic and sub-micronic particles in relation with lead speciation

International Nuclear Information System (INIS)

Uzu, G.; Sobanska, S.; Aliouane, Y.; Pradere, P.; Dumat, C.

2009-01-01

Particles from channelled emissions of a battery recycling facility were size-segregated and investigated to correlate their speciation and morphology with their transfer towards lettuce. Microculture experiments carried out with various calcareous soils spiked with micronic and sub-micronic particles (1650 ± 20 mg Pb kg -1 ) highlighted a greater transfer in soils mixed with the finest particles. According to XRD and Raman spectroscopy results, the two fractions presented differences in the amount of minor lead compounds like carbonates, but their speciation was quite similar, in decreasing order of abundance: PbS, PbSO 4 , PbSO 4 .PbO, α-PbO and Pb 0 . Morphology investigations revealed that PM 2.5 (i.e. Particulate Matter 2.5 composed of particles suspended in air with aerodynamic diameters of 2.5 μm or less) contained many Pb nanoballs and nanocrystals which could influence lead availability. The soil-plant transfer of lead was mainly influenced by size and was very well estimated by 0.01 M CaCl 2 extraction. - The soil-lettuce lead transfer from atmospheric industrial sub-micronic and micronic particles depends on particle size

Clustering of near clusters versus cluster compactness

International Nuclear Information System (INIS)

Yu Gao; Yipeng Jing

1989-01-01

The clustering properties of near Zwicky clusters are studied by using the two-point angular correlation function. The angular correlation functions for compact and medium compact clusters, for open clusters, and for all near Zwicky clusters are estimated. The results show much stronger clustering for compact and medium compact clusters than for open clusters, and that open clusters have nearly the same clustering strength as galaxies. A detailed study of the compactness-dependence of correlation function strength is worth investigating. (author)

Submicron Features in Higher Manganese Silicide

Directory of Open Access Journals (Sweden)

Yatir Sadia

2013-01-01

Full Text Available The world energy crisis had increased the demand for alternative energy sources and as such is one of the topics at the forefront of research. One way for reducing energy consumption is by thermoelectricity. Thermoelectric effects enable direct conversion of thermal into electrical energy. Higher manganese silicide (HMS, MnSi1.75 is one of the promising materials for applications in the field of thermoelectricity. The abundance and low cost of the elements, combined with good thermoelectric properties and high mechanical and chemical stability at high temperatures, make it very attractive for thermoelectric applications. Recent studies have shown that Si-rich HMS has improved thermoelectric properties. The most interesting of which is the unusual reduction in thermal conductivity. In the current research, transmission (TEM and scanning (SEM electron microscopy as well as X-ray diffraction methods were applied for investigation of the govern mechanisms resulting in very low thermal conductivity values of an Si-rich HMS composition, following arc melting and hot-pressing procedures. In this paper, it is shown that there is a presence of sub-micron dislocations walls, stacking faults, and silicon and HMS precipitates inside each other apparent in the matrix, following a high temperature (0.9 Tm hot pressing for an hour. These are not just responsible for the low thermal conductivity values observed but also indicate the ability to create complicate nano-structures that will last during the production process and possibly during the application.

Cluster-cluster clustering

International Nuclear Information System (INIS)

Barnes, J.; Dekel, A.; Efstathiou, G.; Frenk, C.S.; Yale Univ., New Haven, CT; California Univ., Santa Barbara; Cambridge Univ., England; Sussex Univ., Brighton, England)

1985-01-01

The cluster correlation function xi sub c(r) is compared with the particle correlation function, xi(r) in cosmological N-body simulations with a wide range of initial conditions. The experiments include scale-free initial conditions, pancake models with a coherence length in the initial density field, and hybrid models. Three N-body techniques and two cluster-finding algorithms are used. In scale-free models with white noise initial conditions, xi sub c and xi are essentially identical. In scale-free models with more power on large scales, it is found that the amplitude of xi sub c increases with cluster richness; in this case the clusters give a biased estimate of the particle correlations. In the pancake and hybrid models (with n = 0 or 1), xi sub c is steeper than xi, but the cluster correlation length exceeds that of the points by less than a factor of 2, independent of cluster richness. Thus the high amplitude of xi sub c found in studies of rich clusters of galaxies is inconsistent with white noise and pancake models and may indicate a primordial fluctuation spectrum with substantial power on large scales. 30 references

Hydration of Atmospheric Molecular Clusters: Systematic Configurational Sampling.

Science.gov (United States)

Kildgaard, Jens; Mikkelsen, Kurt V; Bilde, Merete; Elm, Jonas

2018-05-09

We present a new systematic configurational sampling algorithm for investigating the potential energy surface of hydrated atmospheric molecular clusters. The algo- rithm is based on creating a Fibonacci sphere around each atom in the cluster and adding water molecules to each point in 9 different orientations. To allow the sam- pling of water molecules to existing hydrogen bonds, the cluster is displaced along the hydrogen bond and a water molecule is placed in between in three different ori- entations. Generated redundant structures are eliminated based on minimizing the root mean square distance (RMSD) of different conformers. Initially, the clusters are sampled using the semiempirical PM6 method and subsequently using density func- tional theory (M06-2X and ωB97X-D) with the 6-31++G(d,p) basis set. Applying the developed algorithm we study the hydration of sulfuric acid with up to 15 water molecules. We find that the additions of the first four water molecules "saturate" the sulfuric acid molecule and are more thermodynamically favourable than the addition of water molecule 5-15. Using the large generated set of conformers, we assess the performance of approximate methods (ωB97X-D, M06-2X, PW91 and PW6B95-D3) in calculating the binding energies and assigning the global minimum conformation compared to high level CCSD(T)-F12a/VDZ-F12 reference calculations. The tested DFT functionals systematically overestimates the binding energies compared to cou- pled cluster calculations, and we find that this deficiency can be corrected by a simple scaling factor.

Reduced impact of induced gate noise on inductively degenerated LNAs in deep submicron CMOS technologies

DEFF Research Database (Denmark)

Rossi, P.; Svelto, F.; Mazzanti, A.

2005-01-01

Designers of radio-frequency inductively-degenerated CMOS low-noise-amplifiers have usually not followed the guidelines for achieving minimum noise figure. Nonetheless, state-of-the- art implementations display noise figure values very close to the theoretical minimum. In this paper, we point out...... that this is due to the effect of the parasitic overlap capacitances in the MOS device. In particular, we show that overlap capacitances lead to a significant induced-gate-noise reduction, especially when deep sub-micron CMOS processes are used....

Size-Tuned Plastic Flow Localization in Irradiated Materials at the Submicron Scale

Science.gov (United States)

Cui, Yinan; Po, Giacomo; Ghoniem, Nasr

2018-05-01

Three-dimensional discrete dislocation dynamics (3D-DDD) simulations reveal that, with reduction of sample size in the submicron regime, the mechanism of plastic flow localization in irradiated materials transitions from irradiation-controlled to an intrinsic dislocation source controlled. Furthermore, the spatial correlation of plastic deformation decreases due to weaker dislocation interactions and less frequent cross slip as the system size decreases, thus manifesting itself in thinner dislocation channels. A simple model of discrete dislocation source activation coupled with cross slip channel widening is developed to reproduce and physically explain this transition. In order to quantify the phenomenon of plastic flow localization, we introduce a "deformation localization index," with implications to the design of radiation-resistant materials.

Occurrence of weak, sub-micron, tropospheric aerosol events at high Arctic latitudes

Science.gov (United States)

O'Neill, N. T.; Pancrati, O.; Baibakov, K.; Eloranta, E.; Batchelor, R. L.; Freemantle, J.; McArthur, L. J. B.; Strong, K.; Lindenmaier, R.

2008-07-01

Numerous fine mode (sub-micron) aerosol optical events were observed during the summer of 2007 at the High Arctic atmospheric observatory (PEARL) located at Eureka, Nunavut, Canada. Half of these events could be traced to forest fires in southern and eastern Russia and the Northwest Territories of Canada. The most notable findings were that (a) a combination of ground-based measurements (passive sunphotometry, high spectral resolution lidar) could be employed to determine that weak (near sub-visual) fine mode events had occurred, and (b) this data combined with remote sensing imagery products (MODIS, OMI-AI, FLAMBE fire sources), Fourier transform spectroscopy and back trajectories could be employed to identify the smoke events.

A cluster of cases of nosocomial legionnaires disease linked to a contaminated hospital decorative water fountain.

Science.gov (United States)

Palmore, Tara N; Stock, Frida; White, Margaret; Bordner, MaryAnn; Michelin, Angela; Bennett, John E; Murray, Patrick R; Henderson, David K

2009-08-01

Nosocomial outbreaks of Legionnaires disease have been linked to contaminated water in hospitals. Immunocompromised patients are particularly vulnerable and, when infected, have a high mortality rate. We report the investigation of a cluster of cases of nosocomial pneumonia attributable to Legionella pneumophila serogroup 1 that occurred among patients on our stem cell transplantation unit. We conducted a record review to identify common points of potential exposure, followed by environmental and water sampling for Legionella species from those sources. We used an air sampler to in an attempt to detect aerosolized Legionella and pulsed-field gel electrophoresis to compare clinical and environmental isolates. The most likely sources identified were the water supply in the patients' rooms and a decorative fountain in the radiation oncology suite. Samples from the patients' rooms did not grow Legionella species. Cultures of the fountain, which had been restarted 4 months earlier after being shut off for 5 months, yielded L. pneumophila serogroup 1. The isolates from both patients and the fountain were identical by pulsed-field gel electrophoresis. Both patients developed pneumonia within 10 days of completing radiation therapy, and each reported having observed the fountain at close range. Both patients' infections were identified early and treated promptly, and both recovered. This cluster was caused by contamination of a decorative fountain despite its being equipped with a filter and ozone generator. Fountains are a potential source of nosocomial Legionnaires disease despite standard maintenance and sanitizing measures. In our opinion, fountains present unacceptable risk in hospitals serving immunocompromised patients.

Calculation of the soft error rate of submicron CMOS logic circuits

International Nuclear Information System (INIS)

Juhnke, T.; Klar, H.

1995-01-01

A method to calculate the soft error rate (SER) of CMOS logic circuits with dynamic pipeline registers is described. This method takes into account charge collection by drift and diffusion. The method is verified by comparison of calculated SER's to measurement results. Using this method, the SER of a highly pipelined multiplier is calculated as a function of supply voltage for a 0.6 microm, 0.3 microm, and 0.12 microm technology, respectively. It has been found that the SER of such highly pipelined submicron CMOS circuits may become too high so that countermeasures have to be taken. Since the SER greatly increases with decreasing supply voltage, low-power/low-voltage circuits may show more than eight times the SER for half the normal supply voltage as compared to conventional designs

Design consideration for dc SQUIDs fabricated in deep sub-micron technology

International Nuclear Information System (INIS)

Ketchen, M.B.

1991-01-01

Design rules for scaling dc SQUID junctions to optimize SQUID performance have been well known for over a decade, and verified down to the sub-micron regime. Practical SQUIDs having well coupled input coils of usable inductance have generally been fabricated at the 2-5 μm level of lithography. Other technologies, silicon in particular, are now routinely practiced at the 0.5 μm level of lithography with impressive demonstrations at the 0.1-0.25 μm level not uncommon. In this paper the implications of applying such fabrication capability to advance dc SQUID technology are explored. In particular the issues of scaling practical dc SQUIDs down to the 0.1-0.25 μm regime are examined, using as a prototype design the basic washer SQUID with a spiral input coil

Proton transport facilitating water-oxidation: the role of second sphere ligands surrounding the catalytic metal cluster.

Science.gov (United States)

Bao, Han; Dilbeck, Preston L; Burnap, Robert L

2013-10-01

The ability of PSII to extract electrons from water, with molecular oxygen as a by-product, is a remarkable biochemical and evolutionary innovation. From an evolutionary perspective, the invention of PSII approximately 2.7 Ga led to the accelerated accumulation of biomass in the biosphere and the accumulation of oxygen in the atmosphere, a combination that allowed for the evolution of a much more complex and extensive biosphere than would otherwise have been possible. From the biochemical and enzymatic perspective, PSII is remarkable because of the thermodynamic and kinetic obstacles that needed to have been overcome to oxidize water as the ultimate photosynthetic electron donor. This article focuses on how proton release is an integral part of how these kinetic and thermodynamic obstacles have been overcome: the sequential removal of protons from the active site of H2O-oxidation facilitates the multistep oxidation of the substrate water at the Mn4CaOx, the catalytic heart of the H2O-oxidation reaction. As noted previously, the facilitated deprotonation of the Mn4CaOx cluster exerts a redox-leveling function preventing the accumulation of excess positive charge on the cluster, which might otherwise hinder the already energetically difficult oxidation of water. Using recent results, including the characteristics of site-directed mutants, the role of the second sphere of amino acid ligands and the associated network of water molecules surrounding the Mn4CaOx is discussed in relation to proton transport in other systems. In addition to the redox-leveling function, a trapping function is assigned to the proton release step occurring immediately prior to the dioxygen chemistry. This trapping appears to involve a yet-to-be clarified gating mechanism that facilitates to coordinated release of a proton from the neighborhood of the active site thereby insuring that the backward charge-recombination reaction does not out-compete the forward reaction of dioxygen chemistry

Particle water and pH in the eastern Mediterranean: source variability and implications for nutrient availability

Science.gov (United States)

Bougiatioti, Aikaterini; Nikolaou, Panayiota; Stavroulas, Iasonas; Kouvarakis, Giorgos; Weber, Rodney; Nenes, Athanasios; Kanakidou, Maria; Mihalopoulos, Nikolaos

2016-04-01

Particle water (liquid water content, LWC) and aerosol pH are important parameters of the aerosol phase, affecting heterogeneous chemistry and bioavailability of nutrients that profoundly impact cloud formation, atmospheric composition, and atmospheric fluxes of nutrients to ecosystems. Few measurements of in situ LWC and pH, however, exist in the published literature. Using concurrent measurements of aerosol chemical composition, cloud condensation nuclei activity, and tandem light scattering coefficients, the particle water mass concentrations associated with the aerosol inorganic (Winorg) and organic (Worg) components are determined for measurements conducted at the Finokalia atmospheric observation station in the eastern Mediterranean between June and November 2012. These data are interpreted using the ISORROPIA-II thermodynamic model to predict the pH of aerosols originating from the various sources that influence air quality in the region. On average, closure between predicted aerosol water and that determined by comparison of ambient with dry light scattering coefficients was achieved to within 8 % (slope = 0.92, R2 = 0.8, n = 5201 points). Based on the scattering measurements, a parameterization is also derived, capable of reproducing the hygroscopic growth factor (f(RH)) within 15 % of the measured values. The highest aerosol water concentrations are observed during nighttime, when relative humidity is highest and the collapse of the boundary layer increases the aerosol concentration. A significant diurnal variability is found for Worg with morning and afternoon average mass concentrations being 10-15 times lower than nighttime concentrations, thus rendering Winorg the main form of particle water during daytime. The average value of total aerosol water was 2.19 ± 1.75 µg m-3, contributing on average up to 33 % of the total submicron mass concentration. Average aerosol water associated with organics, Worg, was equal to 0.56 ± 0.37 µg m-3; thus, organics

A novel submicron emulsion system loaded with vincristine–oleic acid ion-pair complex with improved anticancer effect: in vitro and in vivo studies

Directory of Open Access Journals (Sweden)

Zhang T

2013-03-01

Full Text Available Ting Zhang,1 Yong Zheng,2 iang Peng,3 Xi Cao,1 Tao Gong,1 Zhirong Zhang11Key Laboratory of Drug Targeting and Drug Delivery Systems, Sichuan University, Chengdu, People’s Republic of China; 2Second Affiliated Hospital, Chongqing Medical University, Chongqing, People’s Republic of China; 3State Key Laboratory of Oral Diseases, Sichuan University, Chengdu, People’s Republic of ChinaBackground: Vincristine (VCR, which is a widely used antineoplastic drug, was integrated with a submicron-emulsion drug-delivery system to enhance the anticancer effect.Methods: After the formation of a VCR–oleic acid ion-pair complex (VCR-OA, the VCR-OA-loaded submicron emulsion (VCR-OA-SME, prepared by classical high-pressure homogenization, was characterized and its in vitro anticancer effects were evaluated.Results: The submicron-emulsion formulation exhibited a homogeneous round shape. The mean particle size, zeta potential, and encapsulation efficiency were 157.6 ± 12.6 nm, −26.5 ± 5.0 mV and 78.64% ± 3.44%, respectively. An in vitro release study of the VCR-OA-SME revealed that 12.4% of the VCR was released within the first 2 hours (initial burst-release phase and the rest of the drug was detected in the subsequent sustained-release phase. Compared with VCR solution, the pharmacokinetic study of VCR-OA-SME showed relatively longer mean residence time (mean residence time [0–∞] increased from 187.19 to 227.56 minutes, higher maximum concentration (from 252.13 ng/mL to 533.34 ng/mL, and greater area under the curve (area under the curve [0–∞] from 11,417.77 µg/L/minute to 17,164.34 µg/L/minute. Moreover, the VCR-OA-SME exhibited higher cytotoxicity (P < 0.05 on tumor cells by inducing cell arrest in the G2/M phase or even apoptosis (P < 0.05.Conclusion: The VCR-OA-SME formulation in our study displayed great potential for an anticancer effect for VCR.Keywords: ion-pair complex, submicron emulsion, cytotoxicity, apoptosis, cell uptake

A Density Functional Theory Evaluation of Hydrophobic Solvation: Ne, Ar and Kr in a 50-Water Cluster. Implications for the Hydrophobic Effect.

Science.gov (United States)

Kobko, Nadya; Marianski, Mateusz; Asensio, Amparo; Wieczorek, Robert; Dannenberg, J J

2012-06-15

The physical explanation for the hydrophobic effect has been the subject of disagreement. Physical organic chemists tend to use a explanation related to pressure, while many biochemists prefer an explanation that involves decreased entropy of the aqueous solvent. We present DFT calculations at the B3LYP/6-31G(d,p) and X3LYP/6-31G(d,p) levels on the solvation of three noble gases (Ne, Ar, and Kr) in clusters of 50 waters. Vibrational analyses show no substantial decreases in the vibrational entropies of the waters in any of the three clusters. The observed positive free energies of transfer from the gas phase or from nonpolar solvents to water appear to be due to the work needed to make a suitable hole in the aqueous solvent. We distinguish between hydrophobic solvations (explicitly studied here) and the hydrophobic effect that occurs when a solute (or transition state) can decrease its volume through conformational change (which is not possible for the noble gases).

Analysis system of submicron particle tracks in the fine-grained nuclear emulsion by a combination of hard x-ray and optical microscopy

International Nuclear Information System (INIS)

Naka, T.; Asada, T.; Yoshimoto, M.; Katsuragawa, T.; Tawara, Y.; Umemoto, A.; Suzuki, Y.; Terada, Y.; Takeuchi, A.; Uesugi, K.; Kimura, M.

2015-01-01

Analyses of nuclear emulsion detectors that can detect and identify charged particles or radiation as tracks have typically utilized optical microscope systems because the targets have lengths from several μm to more than 1000 μm. For recent new nuclear emulsion detectors that can detect tracks of submicron length or less, the current readout systems are insufficient due to their poor resolution. In this study, we developed a new system and method using an optical microscope system for rough candidate selection and the hard X-ray microscope system at SPring-8 for high-precision analysis with a resolution of better than 70 nm resolution. Furthermore, we demonstrated the analysis of submicron-length tracks with a matching efficiency of more than 99% and position accuracy of better than 5 μm. This system is now running semi-automatically

Characterization and evaluation of femtosecond laser-induced sub-micron periodic structures generated on titanium to improve osseointegration of implants

Science.gov (United States)

Lee, Bryan E. J.; Exir, Hourieh; Weck, Arnaud; Grandfield, Kathryn

2018-05-01

Reproducible and controllable methods of modifying titanium surfaces for dental and orthopaedic applications are of interest to prevent poor implant outcomes by improving osseointegration. This study made use of a femtosecond laser to generate laser-induced periodic surface structures with periodicities of 300, 620 and 760 nm on titanium substrates. The reproducible rippled patterns showed consistent submicron scale roughness and relatively hydrophobic surfaces as measured by atomic force microscopy and contact angle, respectively. Transmission electron microscopy and Auger electron spectroscopy identified a thicker oxide layer on ablated surfaces compared to controls. In vitro testing was conducted using osteosarcoma Saos-2 cells. Cell metabolism on the laser-ablated surfaces was comparable to controls and alkaline phosphatase activity was notably increased at late time points for the 620 and 760 nm surfaces compared to controls. Cells showed a more elongated shape on laser-ablated surfaces compared to controls and showed perpendicular alignment to the periodic structures. This work has demonstrated the feasibility of generating submicron features on an implant material with the ability to influence cell response and improve implant outcomes.

Sub-micron accurate track navigation method ''Navi'' for the analysis of Nuclear Emulsion

International Nuclear Information System (INIS)

Yoshioka, T; Yoshida, J; Kodama, K

2011-01-01

Sub-micron accurate track navigation in Nuclear Emulsion is realized by using low energy signals detected by automated Nuclear Emulsion read-out systems. Using those much dense ''noise'', about 10 4 times larger than the real tracks, the accuracy of the track position navigation reaches to be sub micron only by using the information of a microscope field of view, 200 micron times 200 micron. This method is applied to OPERA analysis in Japan, i.e. support of human eye checks of the candidate tracks, confirmation of neutrino interaction vertexes and to embed missing track segments to the track data read-out by automated systems.

Sub-micron accurate track navigation method ``Navi'' for the analysis of Nuclear Emulsion

Science.gov (United States)

Yoshioka, T.; Yoshida, J.; Kodama, K.

2011-03-01

Sub-micron accurate track navigation in Nuclear Emulsion is realized by using low energy signals detected by automated Nuclear Emulsion read-out systems. Using those much dense ``noise'', about 104 times larger than the real tracks, the accuracy of the track position navigation reaches to be sub micron only by using the information of a microscope field of view, 200 micron times 200 micron. This method is applied to OPERA analysis in Japan, i.e. support of human eye checks of the candidate tracks, confirmation of neutrino interaction vertexes and to embed missing track segments to the track data read-out by automated systems.

Classification Of Cluster Area Forsatellite Image

Directory of Open Access Journals (Sweden)

Thwe Zin Phyo

2015-06-01

Full Text Available Abstract This paper describes area classification for Landsat7 satellite image. The main purpose of this system is to classify the area of each cluster contained in a satellite image. To classify this image firstly need to clusterthe satellite image into different land cover types. Clustering is an unsupervised learning method that aimsto classify an image into homogeneous regions. This system is implemented based on color features with K-means clustering unsupervised algorithm. This method does not need to train image before clustering.The clusters of satellite image are grouped into a set of three clusters for Landsat7 satellite image. For this work the combined band 432 from Landsat7 satellite is used as an input. Satellite imageMandalay area in 2001 is chosen to test the segmentation method. After clustering a specific range for three clustered images must be defined in order to obtain greenland water and urbanbalance.This system is implemented by using MATLAB programming language.

Examining the structural evolution of bicarbonate–water clusters: insights from photoelectron spectroscopy, basin-hopping structural search, and comparison with available IR spectral studies

Energy Technology Data Exchange (ETDEWEB)

Wen, Hui [Chinese Academy of Sciences (CAS), Hefei (China). Lab. of Atmospheric Physico-Chemistry, Anhui Inst. of Optics & Fine Mechanics; Pacific Northwest National Lab. (PNNL), Richland, WA (United States). Physical Sciences Division; Hou, Gao-Lei [Pacific Northwest National Lab. (PNNL), Richland, WA (United States). Physical Sciences Division; Liu, Yi-Rong [Chinese Academy of Sciences (CAS), Hefei (China). Lab. of Atmospheric Physico-Chemistry, Anhui Inst. of Optics & Fine Mechanics; Wang, Xue-Bin [Pacific Northwest National Lab. (PNNL), Richland, WA (United States). Physical Sciences Division; Huang, Wei [Chinese Academy of Sciences (CAS), Hefei (China). Lab. of Atmospheric Physico-Chemistry, Anhui Inst. of Optics & Fine Mechanics; Univ. of Science and Technology of China, Hefei (China). School of Environmental Science & Optoelectronic Technology

2016-05-31

Bicarbonate serves a crucial biochemical role in the physiological pH buffering system and also has important atmospheric implications. In the current study, HCO₃^$-$(H₂O)_n (n = 0-13) clusters were successfully produced via electrospray ionization of corresponding bulk salt solution, and were characterized by combining negative ion photoelectron spectroscopy and theoretical calculations. The photoelectron spectra reveal that the electron binding energy monotonically increases with the cluster size up to n = 10 and remains largely the same after n > 10. The photo-detaching feature of the solute HCO3$-$itself, which dominates in the small clusters, diminishes with increase of water coverage. Based on the charge distribution and molecular orbital analyses, the universal high electron binding energy tail that dominates in the larger clusters can be attributed to ionization of water. Thus, the transition of ionization from solute to solvent at the size larger than n=10 has been observed. Extensive theoretical structural search based on the Basin-Hopping unbiased method was carried out, and a plethora of low energy isomers have been obtained for each medium and large size. By comparing the simulated photoelectron spectra and calculated electron binding energies with the experiments, as well as by comparing the simulated infrared spectra with previously reported IR spectra, the probable global minima and the structural evolutionary routes are presented. The nature of bicarbonate-water interactions are mainly electrostatic as implied by the electron localization function (ELF) analysis.

Particle water and pH in the Eastern Mediterranean: sources variability and implications for nutrients availability

Science.gov (United States)

Nikolaou, P.; Bougiatioti, A.; Stavroulas, I.; Kouvarakis, G.; Nenes, A.; Weber, R.; Kanakidou, M.; Mihalopoulos, N.

2015-10-01

Particle water (LWC) and aerosol pH drive the aerosol phase, heterogeneous chemistry and bioavailability of nutrients that profoundly impact cloud formation, atmospheric composition and atmospheric fluxes of nutrients to ecosystems. Few measurements of in-situ LWC and pH however exist in the published literature. Using concurrent measurements of aerosol chemical composition, cloud condensation nuclei activity and tandem light scattering coefficients, the particle water mass concentrations associated with the aerosol inorganic (Winorg) and organic (Worg) components are determined for measurements conducted at the Finokalia atmospheric observation station in the eastern Mediterranean between August and November 2012. These data are interpreted using the ISORROPIA-II thermodynamic model to predict pH of aerosols originating from the various sources that influence air quality in the region. On average, closure between predicted aerosol water and that determined by comparison of ambient with dry light scattering coefficients was achieved to within 8 % (slope = 0.92, R2 = 0.8, n = 5201 points). Based on the scattering measurements a parameterization is also derived, capable of reproducing the hygroscopic growth factor (f(RH)) within 15 % of the measured values. The highest aerosol water concentrations are observed during nighttime, when relative humidity is highest and the collapse of the boundary layer increases the aerosol concentration. A significant diurnal variability is found for Worg with morning and afternoon average mass concentrations being 10-15 times lower than nighttime concentrations, thus rendering Winorg the main form of particle water during daytime. The average value of total aerosol water was 2.19 ± 1.75 μg m-3, contributing on average up to 33 % of the total submicron mass concentration. Average aerosol water associated with organics, Worg, was equal to 0.56 ± 0.37 μg m-3, thus organics contributed about 27.5 % to the total aerosol water, mostly

Cyprus solar water heating cluster: A missed opportunity?

International Nuclear Information System (INIS)

Maxoulis, Christos N.; Charalampous, Harris P.; Kalogirou, Soteris A.

2007-01-01

Cyprus is often called the 'sun island' because of the amount of sunshine received all year round. The abundance of solar radiation together with a good technological base has created favourable conditions for the exploitation of solar energy on the island. This led to the development of a pioneering solar collector industry in Cyprus, which in the mid-1980s was flourishing. The result was an outstanding figure of installed solar collector area per inhabitant. Nowadays, Cyprus is cited as the country with the highest solar collector area installed per inhabitant, worldwide. This means that the local market for solar thermal collectors (for domestic applications) is now rather saturated. It was only rational to assume that Cypriot firms equipped with their gained expertise and leading edge would have safeguarded a sustainable growth and have an international orientation, focusing on exports in an emerging European and eastern Mediterranean thermal solar market. Unfortunately, this is not the case today. This paper reviews the economic performance and the competitiveness of Cyprus and the evolution of the solar water heating (SWH) industry using the cluster theory of Michael Porter. Its aim is to give insight and explanations for the success of the sector domestically, its failure with regards to exporting activity, pinpoint the industry in the European map and finally give recommendations for the cross the boarders commercial success of the industry

A novel design of submicron thin film point contacts

International Nuclear Information System (INIS)

Koch, H.

1986-01-01

A thin film point contact design applicable to SIS-, SNS-, and microbridge-type Josephson junctions is presented, which offers potentially advanced junction characteristics (low capacitance, low stray inductance, increased quasi-particle resistance). The design philosophy is based on the fact that a point contact results if two planes having a common symmetry axis but oriented perpendicular to each other are brought into contact with each other. For the case of thin films, instead of two-dimensional planes, the cross section of the resulting ''point''-contact is defined by the thicknesses of the two thin films. Film thicknesses can be controlled much more precisely than lateral dimensions created by lithography. Hence, submicron junction geometries can be achieved using only conventional fabrication techniques. Following this idea, Josephson weak links of the ultrashort microbridge-type have been fabricated by an all-Nb technique having a 0.3-μm X 0.2-μm cross section with a R /SUB q/ I /SUB c/ product (R /SUB q/ = quasiparticle resistance, I /SUB c/ = critical current) of more than 20 mV

Immobilization of trypsin on sub-micron skeletal polymer monolith

Energy Technology Data Exchange (ETDEWEB)

Yao Chunhe [Beijing National Laboratory for Molecular Sciences, Key Laboratory of Analytical Chemistry for Living Biosystems, Institute of Chemistry, Chinese Academy of Sciences, Beijing 100190 (China); Graduate School, Chinese Academy of Sciences, Beijing 100049 (China); Qi Li, E-mail: qili@iccas.ac.cn [Beijing National Laboratory for Molecular Sciences, Key Laboratory of Analytical Chemistry for Living Biosystems, Institute of Chemistry, Chinese Academy of Sciences, Beijing 100190 (China); Hu Wenbin [Beijing National Laboratory for Molecular Sciences, Key Laboratory of Analytical Chemistry for Living Biosystems, Institute of Chemistry, Chinese Academy of Sciences, Beijing 100190 (China); Graduate School, Chinese Academy of Sciences, Beijing 100049 (China); Wang Fuyi [Beijing National Laboratory for Molecular Sciences, Key Laboratory of Analytical Chemistry for Living Biosystems, Institute of Chemistry, Chinese Academy of Sciences, Beijing 100190 (China); Yang Gengliang [College of Pharmacy, Hebei University, Baoding 071002 (China)

2011-04-29

A new kind of immobilized trypsin reactor based on sub-micron skeletal polymer monolith has been developed. Covalent immobilization of trypsin on this support was performed using the epoxide functional groups in either a one- or a multi-step reaction. The proteolytic activity of the immobilized trypsin was measured by monitoring the formation of N-{alpha}-benzoyl-L-arginine (BA) which is the digestion product of a substrate N-{alpha}-benzoyl-L-arginine ethyl ester (BAEE). Results showed that the digestion speed was about 300 times faster than that performed in free solution. The performance of such an enzyme reactor was further demonstrated by digesting protein myoglobin. It has been found that the protein digestion could be achieved in 88 s at 30 deg. C, which is comparable to 24 h digestion in solution at 37 {sup o}C. Furthermore, the immobilized trypsin exhibits increased stability even after continuous use compared to that in free solution. The present monolithic enzyme-reactor provides a promising platform for the proteomic research.

Diffusion and Clustering of Carbon Dioxide on Non-porous Amorphous Solid Water

Energy Technology Data Exchange (ETDEWEB)

He, Jiao; Emtiaz, Shahnewaj M.; Vidali, Gianfranco, E-mail: jhe08@syr.edu, E-mail: gvidali@syr.edu [Physics Department, Syracuse University, Syracuse, NY 13244 (United States)

2017-03-01

Observations by ISO and Spitzer toward young stellar objects showed that CO{sub 2} segregates in the icy mantles covering dust grains. Thermal processing of the ice mixture was proposed as being responsible for the segregation. Although several laboratories studied thermally induced segregation, a satisfying quantification is still missing. We propose that the diffusion of CO{sub 2} along pores inside water ice is the key to quantify segregation. We combined Temperature Programmed Desorption and Reflection Absorption InfraRed Spectroscopy to study how CO{sub 2} molecules interact on a non-porous amorphous solid water (np-ASW) surface. We found that CO{sub 2} diffuses significantly on an np-ASW surface above 65 K and clusters are formed at well below one monolayer. A simple rate equation simulation finds that the diffusion energy barrier of CO{sub 2} on np-ASW is 2150 ± 50 K, assuming a diffusion pre-exponential factor of 10{sup 12} s{sup −1}. This energy should also apply to the diffusion of CO{sub 2} on the wall of pores. The binding energy of CO{sub 2} from CO{sub 2} clusters and CO{sub 2} from H{sub 2}O ice has been found to be 2415 ± 20 K and 2250 ± 20 K, respectively, assuming the same prefactor for desorption. CO{sub 2}–CO{sub 2} interaction is stronger than CO{sub 2}–H{sub 2}O interaction, in agreement with the experimental finding that CO{sub 2} does not wet the np-ASW surface. For comparison, we carried out similar experiments with CO on np-ASW, and found that the CO–CO interaction is always weaker than CO–H{sub 2}O. As a result, CO wets the np-ASW surface. This study should be of help to uncover the thermal history of CO{sub 2} on the icy mantles of dust grains.

Infrared spectroscopy of ionic clusters

International Nuclear Information System (INIS)

Price, J.M.

1990-11-01

This thesis describes new experiments wherein the infrared vibrational predissociation spectra of a number of mass-selected ionic cluster systems have been obtained and analyzed in the 2600 to 4000 cm -1 region. The species studied include: the hydrated hydronium ions, H 3 O + (H 2 O) 3 -10 , ammoniated ammonium ions, NH 4 + (NH 3 ) 1 -10 and cluster ions involving both water and ammonia around an ammonium ion core, (mixed clusters) NH 4 + (NH 3 ) n (H 2 O) m (n+m=4). In each case, the spectra reveal well resolved structures that can be assigned to transitions arising from the vibrational motions of both the ion core of the clusters and the surrounding neutral solvent molecules. 154 refs., 19 figs., 8 tabs

Total dose effects on the matching properties of deep submicron MOS transistors

International Nuclear Information System (INIS)

Wang Yuxin; Hu Rongbin; Li Ruzhang; Chen Guangbing; Fu Dongbing; Lu Wu

2014-01-01

Based on 0.18 μm MOS transistors, for the first time, the total dose effects on the matching properties of deep submicron MOS transistors are studied. The experimental results show that the total dose radiation magnifies the mismatch among identically designed MOS transistors. In our experiments, as the radiation total dose rises to 200 krad, the threshold voltage and drain current mismatch percentages of NMOS transistors increase from 0.55% and 1.4% before radiation to 17.4% and 13.5% after radiation, respectively. PMOS transistors seem to be resistant to radiation damage. For all the range of radiation total dose, the threshold voltage and drain current mismatch percentages of PMOS transistors keep under 0.5% and 2.72%, respectively. (semiconductor devices)

Efficient active waveguiding properties of Mo6 nano-cluster-doped polymer nanotubes

Science.gov (United States)

Bigeon, J.; Huby, N.; Amela-Cortes, M.; Molard, Y.; Garreau, A.; Cordier, S.; Bêche, B.; Duvail, J.-L.

2016-06-01

We investigate 1D nanostructures based on a Mo6@SU8 hybrid nanocomposite in which photoluminescent Mo6 clusters are embedded in the photosensitive SU8 resist. Tens of micrometers long Mo6@SU8-based tubular nanostructures were fabricated by the wetting template method, enabling the control of the inner and outer diameter to about 190 nm and 240 nm respectively, as supported by structural and optical characterizations. The image plane optical study of these nanotubes under optical pumping highlights the efficient waveguiding phenomenon of the red luminescence emitted by the clusters. Moreover, the wave vector distribution in the Fourier plane determined by leakage radiation microscopy gives additional features of the emission and waveguiding. First, the anisotropic red luminescence of the whole system can be attributed to the guided mode along the nanotube. Then, a low-loss propagation behavior is evidenced in the Mo6@SU8-based nanotubes. This result contrasts with the weaker waveguiding signature in the case of UV210-based nanotubes embedding PFO (poly(9,9-di-n-octylfluorenyl-2,7-diyl)). It is attributed to the strong reabsorption phenomenon, owing to overlapping between absorption and emission bands in the semi-conducting conjugated polymer PFO. These results make this Mo6@SU8 original class of nanocomposite a promising candidate as nanosources for submicronic photonic integration.

Ultrarapid Multimode Microwave Synthesis of Nano/Submicron β-SiC

Directory of Open Access Journals (Sweden)

Min Zhao

2018-02-01

Full Text Available This paper presents the design, development and realization of a fast and novel process for the synthesis of 3C silicon carbide (β-SiC nanorods and submicron powder. Using SiO2 (or Si and activated carbon (AC, this process allows β-SiC to be synthesized with almost 100% purity in timeframes of seconds or minutes using multimode microwave rotary tube reactors under open-air conditions. The synthesis temperature used was 1460 ± 50 °C for Si + AC and 1660 ± 50 °C for SiO2 + AC. The shortest β-SiC synthesis time achieved was about 20 s for Si + AC and 100 s for SiO2 + AC. This novel synthesis method allows for scaled-up flow processes in the rapid industrial-scale production of β-SiC, having advantages of time/energy saving and carbon dioxide emission reduction over comparable modern processes.

Submicron hollow spot generation by solid immersion lens and structured illumination

International Nuclear Information System (INIS)

Kim, M-S; Scharf, T; Herzig, H P; Assafrao, A C; Wachters, A J H; Pereira, S F; Urbach, H P; Brun, M; Olivier, S; Nicoletti, S

2012-01-01

We report on the experimental and numerical demonstration of immersed submicron-size hollow focused spots, generated by structuring the polarization state of an incident light beam impinging on a micro-size solid immersion lens (μ-SIL) made of SiO 2 . Such structured focal spots are characterized by a doughnut-shaped intensity distribution, whose central dark region is of great interest for optical trapping of nano-size particles, super-resolution microscopy and lithography. In this work, we have used a high-resolution interference microscopy technique to measure the structured immersed focal spots, whose dimensions were found to be significantly reduced due to the immersion effect of the μ-SIL. In particular, a reduction of 37% of the dark central region was verified. The measurements were compared with a rigorous finite element method model for the μ-SIL, revealing excellent agreement between them. (paper)

Water network-mediated, electron-induced proton transfer in [C{sub 5}H{sub 5}N ⋅ (H{sub 2}O){sub n}]{sup −} clusters

Energy Technology Data Exchange (ETDEWEB)

DeBlase, Andrew F.; Wolke, Conrad T.; Johnson, Mark A., E-mail: jordan@pitt.edu, E-mail: nhammer@olemiss.edu, E-mail: mark.johnson@yale.edu [Department of Chemistry, Yale University, P.O. Box 208107, New Haven, Connecticut 06520 (United States); Weddle, Gary H. [Department of Chemistry, Yale University, P.O. Box 208107, New Haven, Connecticut 06520 (United States); Department of Chemistry, Fairfield University, 1073 North Benson Road, Fairfield, Connecticut 06824 (United States); Archer, Kaye A.; Jordan, Kenneth D., E-mail: jordan@pitt.edu, E-mail: nhammer@olemiss.edu, E-mail: mark.johnson@yale.edu [Department of Chemistry, University of Pittsburgh, 219 Parkman Avenue, Pittsburgh, Pennsylvania 15260 (United States); Kelly, John T.; Tschumper, Gregory S.; Hammer, Nathan I., E-mail: jordan@pitt.edu, E-mail: nhammer@olemiss.edu, E-mail: mark.johnson@yale.edu [Department of Chemistry and Biochemistry, University of Mississippi, University, Mississippi 38677 (United States)

2015-10-14

The role of proton-assisted charge accommodation in electron capture by a heterocyclic electron scavenger is investigated through theoretical analysis of the vibrational spectra of cold, gas phase [Py ⋅ (H{sub 2}O){sub n=3−5}]{sup −} clusters. These radical anions are formed when an excess electron is attached to water clusters containing a single pyridine (Py) molecule in a supersonic jet ion source. Under these conditions, the cluster ion distribution starts promptly at n = 3, and the photoelectron spectra, combined with vibrational predissociation spectra of the Ar-tagged anions, establish that for n > 3, these species are best described as hydrated hydroxide ions with the neutral pyridinium radical, PyH{sup (0)}, occupying one of the primary solvation sites of the OH{sup −}. The n = 3 cluster appears to be a special case where charge localization on Py and hydroxide is nearly isoenergetic, and the nature of this species is explored with ab initio molecular dynamics calculations of the trajectories that start from metastable arrangements of the anion based on a diffuse, essentially dipole-bound electron. These calculations indicate that the reaction proceeds via a relatively slow rearrangement of the water network to create a favorable hydration configuration around the water molecule that eventually donates a proton to the Py nitrogen atom to yield the product hydroxide ion. The correlation between the degree of excess charge localization and the evolving shape of the water network revealed by this approach thus provides a microscopic picture of the “solvent coordinate” at the heart of a prototypical proton-coupled electron transfer reaction.

Selective Propene Epoxidation on Immobilized Au_6-10 Clusters: The Effect of Hydrogen and Water on Activity and Selectivity

DEFF Research Database (Denmark)

Lee, Sungsik; Molina, Luis M.; López, María J.

2009-01-01

Epoxidation made easy: Subnanometer gold clusters immobilized on amorphous alumina result in a highly active and selective catalyst for propene epoxidation. The highest selectivity is found for gas mixtures involving oxygen and water, thus avoiding the use of hydrogen. Ab initio DFT calculations ...

Hydrodynamic clustering of droplets in turbulence

Science.gov (United States)

Kunnen, Rudie; Yavuz, Altug; van Heijst, Gertjan; Clercx, Herman

2017-11-01

Small, inertial particles are known to cluster in turbulent flows: particles are centrifuged out of eddies and gather in the strain-dominated regions. This so-called preferential concentration is reflected in the radial distribution function (RDF; a quantitative measure of clustering). We study clustering of water droplets in a loudspeaker-driven turbulence chamber. We track the motion of droplets in 3D and calculate the RDF. At moderate scales (a few Kolmogorov lengths) we find the typical power-law scaling of preferential concentration in the RDF. However, at even smaller scales (a few droplet diameters), we encounter a hitherto unobserved additional clustering. We postulate that the additional clustering is due to hydrodynamic interactions, an effect which is typically disregarded in modeling. Using a perturbative expansion of inertial effects in a Stokes-flow description of two interacting spheres, we obtain an expression for the RDF which indeed includes the additional clustering. The additional clustering enhances the collision probability of droplets, which enhances their growth rate due to coalescence. The additional clustering is thus an essential effect in precipitation modeling.

Two-surface Monte Carlo with basin hopping: quantum mechanical trajectory and multiple stationary points of water cluster.

Science.gov (United States)

Bandyopadhyay, Pradipta

2008-04-07

The efficiency of the two-surface monte carlo (TSMC) method depends on the closeness of the actual potential and the biasing potential used to propagate the system of interest. In this work, it is shown that by combining the basin hopping method with TSMC, the efficiency of the method can be increased by several folds. TSMC with basin hopping is used to generate quantum mechanical trajectory and large number of stationary points of water clusters.

Effectiveness and feasibility of long-lasting insecticide-treated curtains and water container covers for dengue vector control in Colombia: a cluster randomised trial.

Science.gov (United States)

Quintero, Juliana; García-Betancourt, Tatiana; Cortés, Sebastian; García, Diana; Alcalá, Lucas; González-Uribe, Catalina; Brochero, Helena; Carrasquilla, Gabriel

2015-02-01

Long-lasting insecticide-treated net (LLIN) window and door curtains alone or in combination with LLIN water container covers were analysed regarding effectiveness in reducing dengue vector density, and feasibility of the intervention. A cluster randomised trial was conducted in an urban area of Colombia comparing 10 randomly selected control and 10 intervention clusters. In control clusters, routine vector control activities were performed. The intervention delivered first, LLIN curtains (from July to August 2013) and secondly, water container covers (from October to March 2014). Cross-sectional entomological surveys were carried out at baseline (February 2013 to June 2013), 9 weeks after the first intervention (August to October 2013), and 4-6 weeks after the second intervention (March to April 2014). Curtains were installed in 922 households and water container covers in 303 households. The Breteau index (BI) fell from 14 to 6 in the intervention group and from 8 to 5 in the control group. The additional intervention with LLIN covers for water containers showed a significant reduction in pupae per person index (PPI) (p=0.01). In the intervention group, the PPI index showed a clear decline of 71% compared with 25% in the control group. Costs were high but options for cost savings were identified. Short term impact evaluation indicates that the intervention package can reduce dengue vector density but sustained effect will depend on multiple factors. © The author 2015. The World Health Organization has granted Oxford University Press permission for the reproduction of this article.

Effects of neglecting carrier tunneling on electrostatic potential in calculating direct tunneling gate current in deep submicron MOSFETs

OpenAIRE

Hakim, MMA; Haque, A

2002-01-01

We investigate the validity of the assumption of neglecting carrier tunneling effects on self-consistent electrostatic potential in calculating direct tunneling gate current in deep submicron MOSFETs. Comparison between simulated and experimental results shows that for accurate modeling of direct tunneling current, tunneling effects on potential profile need to be considered. The relative error in gate current due to neglecting carrier tunneling is higher at higher gate voltages and increases...

Dependence of the Internal Structure on Water/Particle Volume Ratio in an Amphiphilic Janus Particle-Water-Oil Ternary System: From Micelle-like Clusters to Emulsions of Spherical Droplets.

Science.gov (United States)

Noguchi, Tomohiro G; Iwashita, Yasutaka; Kimura, Yasuyuki

2017-01-31

Amphiphilic Janus particles (AJP), composed of hydrophilic and hydrophobic hemispheres, are one of the simplest anisotropic colloids, and they exhibit higher surface activities than particles with homogeneous surface properties. Consequently, a ternary system of AJP, water, and oil can form extremely stable Pickering emulsions, with internal structures that depend on the Janus structure of the particles and the system composition. However, the detail of these structures has not been fully explored, especially for the composition range where the amount of the minority liquid phase and AJP are comparable, where one would expect the Janus characteristics to be directly reflected. In this study, we varied the volume ratio of the particles and the minority liquid phase, water, by 2 orders of magnitude around the comparable composition range, and observed the resultant structures at the resolution of the individual particle dimensions by optical microscopy. When the volume ratio of water is smaller than that of the Janus particles, capillary interactions between the hydrophilic hemispheres of the particles induce micelle-like clusters in which the hydrophilic sides of the particles face inward. With increasing water content, these clusters grow into a rodlike morphology. When the water volume exceeds that of the particles, the structure transforms into an emulsion state composed of spherical droplets, colloidosomes, because of the surface activity of particles at the liquid-liquid interface. Thus, we found that a change in volume fraction alters the mechanism of structure formation in the ternary system, and large resulting morphological changes in the self-assembled structures reflect the anisotropy of the particles. The self-assembly shows essential commonalities with that in microemulsions of surfactant molecules, however the AJP system is stabilized only kinetically. Analysis of the dependence of the emulsion droplet size on composition shows that almost all the

Effects of water quality, sanitation, handwashing, and nutritional interventions on child development in rural Kenya (WASH Benefits Kenya): a cluster-randomised controlled trial.

Science.gov (United States)

Stewart, Christine P; Kariger, Patricia; Fernald, Lia; Pickering, Amy J; Arnold, Charles D; Arnold, Benjamin F; Hubbard, Alan E; Dentz, Holly N; Lin, Audrie; Meerkerk, Theodora J; Milner, Erin; Swarthout, Jenna; Colford, John M; Null, Clair

2018-04-01

Poor nutrition and infectious diseases can prevent children from reaching their developmental potential. We aimed to assess the effects of improvements in water, sanitation, handwashing, and nutrition on early child development in rural Kenya. In this cluster-randomised controlled trial, we enrolled pregnant women in their second or third trimester from three counties (Kakamega, Bungoma, and Vihiga) in Kenya's western region, with an average of 12 households per cluster. Groups of nine geographically adjacent clusters were block-randomised, using a random number generator, into the six intervention groups (including monthly visits to promote target behaviours), a passive control group (no visits), or a double-sized active control group (monthly household visits to measure child mid-upper arm circumference). The six intervention groups were: chlorinated drinking water; improved sanitation; handwashing with soap; combined water, sanitation, and handwashing; improved nutrition through counselling and provision of lipid-based nutrient supplements; and combined water, sanitation, handwashing, and nutrition. Here we report on the prespecified secondary child development outcomes: gross motor milestone achievement assessed with the WHO module at year 1, and communication, gross motor, personal social, and combined scores measured by the Extended Ages and Stages Questionnaire (EASQ) at year 2. Masking of participants was not possible, but data assessors were masked. Analyses were by intention to treat. This trial is registered with ClinicalTrials.gov, number NCT01704105. Between Nov 27, 2012, and May 21, 2014, 8246 women residing in 702 clusters were enrolled. No clusters were lost to follow-up, but 2212 households with 2279 children were lost to follow-up by year 2. 5791 (69%) children were measured at year 1 and 6107 (73%) at year 2. At year 1, compared with the active control group, the combined water, sanitation, handwashing, and nutrition group had greater rates of

Critical current and electric transport properties of superconducting epitaxial Nb(Ti)N submicron structures

Science.gov (United States)

Klimov, A.; Słysz, W.; Guziewicz, M.; Kolkovsky, V.; Wegrzecki, M.; Bar, J.; Marchewka, M.; Seredyński, B.

2016-12-01

Critical current and current-voltage characteristics of epitaxial Nb(Ti)N submicron ultrathin structures were measured as function of temperature. For 700-nm-wide bridge we found current-driven vortex de-pinning at low temperatures and thermally activated flux flow closer to the transition temperature, as the limiting factors for the critical current density. For 100-nm-wide meander we observed combination of phase-slip activation and vortex-anti-vortex pair (VAP) thermal excitation. Our Nb(Ti)N meander structure demonstrates high de-pairing critical current densities 107 A/cm2 at low temperatures, but the critical currents are much smaller due to presence of the local constrictions.

Revisiting a many-body model for water based on a single polarizable site: from gas phase clusters to liquid and air/liquid water systems.

Science.gov (United States)

Réal, Florent; Vallet, Valérie; Flament, Jean-Pierre; Masella, Michel

2013-09-21

We present a revised version of the water many-body model TCPE [M. Masella and J.-P. Flament, J. Chem. Phys. 107, 9105 (1997)], which is based on a static three charge sites and a single polarizable site to model the molecular electrostatic properties of water, and on an anisotropic short range many-body energy term specially designed to accurately model hydrogen bonding in water. The parameters of the revised model, denoted TCPE/2013, are here developed to reproduce the ab initio energetic and geometrical properties of small water clusters (up to hexamers) and the repulsive water interactions occurring in cation first hydration shells. The model parameters have also been refined to reproduce two liquid water properties at ambient conditions, the density and the vaporization enthalpy. Thanks to its computational efficiency, the new model range of applicability was validated by performing simulations of liquid water over a wide range of temperatures and pressures, as well as by investigating water liquid/vapor interfaces over a large range of temperatures. It is shown to reproduce several important water properties at an accurate enough level of precision, such as the existence liquid water density maxima up to a pressure of 1000 atm, the water boiling temperature, the properties of the water critical point (temperature, pressure, and density), and the existence of a "singularity" temperature at about 225 K in the supercooled regime. This model appears thus to be particularly well-suited for characterizing ion hydration properties under different temperature and pressure conditions, as well as in different phases and interfaces.

Improved Light Conversion Efficiency Of Dye-Sensitized Solar Cell By Dispersing Submicron-Sized Granules Into The Nano-Sized TiO2 Layer

Directory of Open Access Journals (Sweden)

Song S.A.

2015-06-01

Full Text Available In this work, TiO2 nanoparticles and submicron-sized granules were synthesized by a hydrothermal method and spray pyrolysis, respectively. Submicron-sized granules were dispersed into the nano-sized TiO2 layer to improve the light conversion efficiency. Granules showed better light scattering, but lower in terms of the dye-loading quantity and recombination resistance compared with nanoparticles. Consequently, the nano-sized TiO2 layer had higher cell efficiency than the granulized TiO2 layer. When dispersed granules into the nanoparticle layer, the light scattering was enhanced without the loss of dye-loading quantities. The dispersion of granulized TiO2 led to increase the cell efficiency up to 6.51%, which was about 5.2 % higher than that of the electrode consisting of only TiO2 nanoparticles. Finally, the optimal hydrothermal temperature and dispersing quantity of granules were found to be 200°C and 20 wt%, respectively.

U.S. EPA Water Technology Innovation Cluster Leaders Meeting - "Successfully Supporting Early-Stage Companies: The Role of Technology Testing" Meeting Summary Report

Science.gov (United States)

The goals of this workshop were to: (1) increase the cluster leaders’ level of knowledge regarding past and current water technology testing programs, facilities and requirements; (2) learn from the experiences of technology vendors in getting innovative, commercial-ready product...

Kernel Clustering with a Differential Harmony Search Algorithm for Scheme Classification

Directory of Open Access Journals (Sweden)

Yu Feng

2017-01-01

Full Text Available This paper presents a kernel fuzzy clustering with a novel differential harmony search algorithm to coordinate with the diversion scheduling scheme classification. First, we employed a self-adaptive solution generation strategy and differential evolution-based population update strategy to improve the classical harmony search. Second, we applied the differential harmony search algorithm to the kernel fuzzy clustering to help the clustering method obtain better solutions. Finally, the combination of the kernel fuzzy clustering and the differential harmony search is applied for water diversion scheduling in East Lake. A comparison of the proposed method with other methods has been carried out. The results show that the kernel clustering with the differential harmony search algorithm has good performance to cooperate with the water diversion scheduling problems.

A new apparatus for the study of electron impact fragmentation of molecular clusters

International Nuclear Information System (INIS)

Barrett, G; Burgt, P J M van der

2008-01-01

This paper reports on the development of a new experiment for the study of electron-impact induced dissociation and fragmentation of molecular clusters and biomolecules and other species solvated in water clusters. The purpose is to look at clusters that are of interest to biophysics, atmospheric physics, and other fields. The experiment consists of a differentially pumped vacuum system, with an expansion chamber to generate a pulsed supersonic beam of clusters, and a collision chamber where the cluster beam intersects with an electron beam. Water clusters can be seeded with biomolecules emerging from a resistively heated oven. Investigation will be possible into both ion yields and long-lived neutral metastable yields produced by electron-impact fragmentation of relevant clusters and biomolecules

Plastic deformation of submicron-sized crystals studied by in-situ Kikuchi diffraction and dislocation imaging

DEFF Research Database (Denmark)

Zhang, Xiaodan; Godfrey, Andrew; Winther, Grethe

2012-01-01

The plastic deformation of submicron-size copper single crystals in the form of pillars has been characterized during in-situ compression in the transmission electron microscope up to strains of 28–33% using a state-of-the-art holder (PI-95 PicoIndenter). The dimensions of the crystals used were...... approx. 500×250×200 nm3 with the compression axis oriented 1.6° from [110]. Local crystallographic orientations have been determined with high accuracy using a Kikuchi diffraction method and glide of dislocations over a pillar has also been observed directly by dark field imaging. The variation...

Particle water and pH in the eastern Mediterranean: source variability and implications for nutrient availability

Directory of Open Access Journals (Sweden)

A. Bougiatioti

2016-04-01

Full Text Available Particle water (liquid water content, LWC and aerosol pH are important parameters of the aerosol phase, affecting heterogeneous chemistry and bioavailability of nutrients that profoundly impact cloud formation, atmospheric composition, and atmospheric fluxes of nutrients to ecosystems. Few measurements of in situ LWC and pH, however, exist in the published literature. Using concurrent measurements of aerosol chemical composition, cloud condensation nuclei activity, and tandem light scattering coefficients, the particle water mass concentrations associated with the aerosol inorganic (Winorg and organic (Worg components are determined for measurements conducted at the Finokalia atmospheric observation station in the eastern Mediterranean between June and November 2012. These data are interpreted using the ISORROPIA-II thermodynamic model to predict the pH of aerosols originating from the various sources that influence air quality in the region. On average, closure between predicted aerosol water and that determined by comparison of ambient with dry light scattering coefficients was achieved to within 8 % (slope  =  0.92, R2  =  0.8, n  =  5201 points. Based on the scattering measurements, a parameterization is also derived, capable of reproducing the hygroscopic growth factor (f(RH within 15 % of the measured values. The highest aerosol water concentrations are observed during nighttime, when relative humidity is highest and the collapse of the boundary layer increases the aerosol concentration. A significant diurnal variability is found for Worg with morning and afternoon average mass concentrations being 10–15 times lower than nighttime concentrations, thus rendering Winorg the main form of particle water during daytime. The average value of total aerosol water was 2.19 ± 1.75 µg m−3, contributing on average up to 33 % of the total submicron mass concentration. Average aerosol water associated with

ADAPTIVE OPTICS OBSERVATIONS OF 3 {mu}m WATER ICE IN SILHOUETTE DISKS IN THE ORION NEBULA CLUSTER AND M43

Energy Technology Data Exchange (ETDEWEB)

Terada, Hiroshi; Pyo, Tae-Soo; Minowa, Yosuke; Hayano, Yutaka; Oya, Shin; Hattori, Masayuki; Takami, Hideki [Subaru Telescope, National Astronomical Observatory of Japan, 650 North A' ohoku Place, Hilo, HI 96720 (United States); Tokunaga, Alan T. [Institute for Astronomy, University of Hawaii, 2680 Woodlawn Drive, Honolulu, HI 96822 (United States); Watanabe, Makoto [Department of Cosmosciences, Hokkaido University, Kita 10, Nishi 8, Kita-ku, Sapporo, Hokkaido 060-0810 (Japan); Saito, Yoshihiko [Department of Physics, Tokyo Institute of Technology, 2-12-1 Ookayama, Meguro, Tokyo 152-8551 (Japan); Ito, Meguru [Department of Mechanical Engineering, University of Victoria, 3800 Finnerty Road, Victoria, BC, V8P 5C2 (Canada); Iye, Masanori, E-mail: terada@subaru.naoj.org [National Astronomical Observatory of Japan, 2-21-1 Osawa, Mitaka, Tokyo 181-8588 (Japan)

2012-12-01

We present the near-infrared images and spectra of four silhouette disks in the Orion Nebula Cluster (M42) and M43 using the Subaru Adaptive Optics system. While d053-717 and d141-1952 show no water ice feature at 3.1 {mu}m, a moderately deep ({tau}{sub ice} {approx} 0.7) water ice absorption is detected toward d132-1832 and d216-0939. Taking into account the water ice so far detected in the silhouette disks, the critical inclination angle to produce a water ice absorption feature is confirmed to be 65 Degree-Sign -75 Degree-Sign . As for d216-0939, the crystallized water ice profile is exactly the same as in the previous observations taken 3.63 years ago. If the water ice material is located at 30 AU, then the observations suggest it is uniform at a scale of about 3.5 AU.

Infrared spectroscopy of ionic clusters

Energy Technology Data Exchange (ETDEWEB)

Price, J.M. (California Univ., Berkeley, CA (USA). Dept. of Chemistry Lawrence Berkeley Lab., CA (USA))

1990-11-01

This thesis describes new experiments wherein the infrared vibrational predissociation spectra of a number of mass-selected ionic cluster systems have been obtained and analyzed in the 2600 to 4000 cm{sup {minus}1} region. The species studied include: the hydrated hydronium ions, H{sub 3}O{sup +} (H{sub 2}O){sub 3 {minus}10}, ammoniated ammonium ions, NH{sub 4}{sup +}(NH{sub 3}){sub 1 {minus}10} and cluster ions involving both water and ammonia around an ammonium ion core, (mixed clusters) NH{sub 4}{sup +}(NH{sub 3}){sub n}(H{sub 2}O){sub m} (n+m=4). In each case, the spectra reveal well resolved structures that can be assigned to transitions arising from the vibrational motions of both the ion core of the clusters and the surrounding neutral solvent molecules. 154 refs., 19 figs., 8 tabs.

Measurements of Burnout Conditions for Flow of Boiling Water in Vertical 3-Rod and 7-Rod Clusters

Energy Technology Data Exchange (ETDEWEB)

Becker, Kurt M; Hernborg, G; Flinta, J E

1964-08-15

The present report deals with measurements of burnout conditions for flow of boiling water in vertical 3-rod and 7-rod clusters. Data were obtained,in respect of heating the rods only, as well as for simultaneous uniform and non-uniform heating of the rods and the shroud. Totally, 520 runs were performed. In the case of equal heat fluxes on all surfaces of the channels, burnout always occurred on the rods, and the data were low by a factor of about 1.3 compared with round duct data. When only the rods were heated, the data showed very low burnout values in comparison with the results for total uniform heating and round ducts. This disagreement was explained by considering the climbing film flow model and the fact that only a fraction of the channel perimeter was heated. For simultaneous and non-uniform heating of the rods and the shroud it was found that the shroud could be overloaded up to 50 per cent without reducing the margin of safety in respect of burnout for the rod cluster. Finally, a correlation for predicting burnout conditions in round ducts, annuli and rod clusters has been presented. This correlation predicts the burnout heat fluxes for the present measurements and previously obtained annuli measurements within {+-} 5 per cent.

Evaluation of B3LYP, X3LYP, and M06-class density functionals for predicting the binding energies of neutral, protonated, and deprotonated water clusters

OpenAIRE

Bryantsev, Vyacheslav S.; Diallo, Mamadou S.; van Duin, Adri C. T.; Goddard, William A., III

2009-01-01

In this paper we assess the accuracy of the B3LYP, X3LYP, and newly developed M06-L, M06-2X, and M06 functionals to predict the binding energies of neutral and charged water clusters including (H_2O)_n, n = 2−8, 20), H_3O+(H_2O_)n, n = 1−6, and OH−(H_2O)_n, n = 1−6. We also compare the predicted energies of two ion hydration and neutralization reactions on the basis of the calculated binding energies. In all cases, we use as benchmarks calculated binding energies of water clusters extrapolate...

Effects of water quality, sanitation, handwashing, and nutritional interventions on diarrhoea and child growth in rural Bangladesh: a cluster randomised controlled trial

Directory of Open Access Journals (Sweden)

Stephen P Luby, ProfMD

2018-03-01

Full Text Available Summary: Background: Diarrhoea and growth faltering in early childhood are associated with subsequent adverse outcomes. We aimed to assess whether water quality, sanitation, and handwashing interventions alone or combined with nutrition interventions reduced diarrhoea or growth faltering. Methods: The WASH Benefits Bangladesh cluster-randomised trial enrolled pregnant women from villages in rural Bangladesh and evaluated outcomes at 1-year and 2-years' follow-up. Pregnant women in geographically adjacent clusters were block-randomised to one of seven clusters: chlorinated drinking water (water; upgraded sanitation (sanitation; promotion of handwashing with soap (handwashing; combined water, sanitation, and handwashing; counselling on appropriate child nutrition plus lipid-based nutrient supplements (nutrition; combined water, sanitation, handwashing, and nutrition; and control (data collection only. Primary outcomes were caregiver-reported diarrhoea in the past 7 days among children who were in utero or younger than 3 years at enrolment and length-for-age Z score among children born to enrolled pregnant women. Masking was not possible for data collection, but analyses were masked. Analysis was by intention to treat. This trial is registered at ClinicalTrials.gov, number NCC01590095. Findings: Between May 31, 2012, and July 7, 2013, 5551 pregnant women in 720 clusters were randomly allocated to one of seven groups. 1382 women were assigned to the control group; 698 to water; 696 to sanitation; 688 to handwashing; 702 to water, sanitation, and handwashing; 699 to nutrition; and 686 to water, sanitation, handwashing, and nutrition. 331 (6% women were lost to follow-up. Data on diarrhoea at year 1 or year 2 (combined were available for 14 425 children (7331 in year 1, 7094 in year 2 and data on length-for-age Z score in year 2 were available for 4584 children (92% of living children were measured at year 2. All interventions had high adherence

Submicron particulate organic matter in the urban atmosphere: a new method for real-time measurement, molecular-level characterization and source apportionment

Science.gov (United States)

Müller, Markus; Eichler, Philipp; D'Anna, Barbara; Tan, Wen; Wisthaler, Armin

2017-04-01

We used a novel chemical analytical method for measuring submicron particulate organic matter in the atmosphere of three European cities (Innsbruck, Lyon, Valencia). Proton-Transfer-Reaction Time-of-Flight Mass Spectrometry (PTR-ToF-MS) was used in combination with the "chemical analysis of aerosol online" (CHARON) inlet for detecting particulate organic compounds on-line (i.e. without filter pre-collection), in real-time (1-min time resolution), at ng m-3 concentrations, with molecular-level resolution (i.e. obtaining molecular weight and elemental composition information). The CHARON-PTR-ToF-MS system monitored molecular tracers associated with different particle sources including levoglucosan from biomass combustion, PAHs from vehicular traffic, nicotine from cigarette smoking, and monoterpene oxidation products secondarily formed from biogenic emissions. The tracer information was used for interpreting positive matrix factorization (PMF) data which allowed us to apportion the sources of submicron particulate organic matter in the different urban environments. This work was funded through the PIMMS ITN, which was supported by the European Commission's 7th Framework Programme under grant agreement number 287382.

DFT Calculation of IR Absorption Spectra for PCE-nH2O, TCE-nH2O, DCE-nH2O, VC-nH2O for Small and Water-Dominated Molecular Clusters

Science.gov (United States)

2017-10-31

VC-nH2O for Small and Water-Dominated Molecular Clusters October 31, 2017 Approved for public release; distribution is unlimited. L. Huang S.g...Calculation of IR Absorption Spectra for PCE-nH2O, TCE-nH2O, DCE-nH2O, VC-nH2O for Small and Water-Dominated Molecular Clusters L. Huang,1 S.G...nH2O molecular clusters using density function theory (DFT). DFT can provide interpretation of absorption spectra with respect to molecular

Bivariate functional data clustering: grouping streams based on a varying coefficient model of the stream water and air temperature relationship

Science.gov (United States)

H. Li; X. Deng; Andy Dolloff; E. P. Smith

2015-01-01

A novel clustering method for bivariate functional data is proposed to group streams based on their water–air temperature relationship. A distance measure is developed for bivariate curves by using a time-varying coefficient model and a weighting scheme. This distance is also adjusted by spatial correlation of streams via the variogram. Therefore, the proposed...

Burnout Conditions for Flow of Boiling Water in Vertical Rod Clusters

Energy Technology Data Exchange (ETDEWEB)

Becker, Kurt M

1962-05-15

This paper deals with a new concept for predicting burnout conditions for forced convection of boiling water in fuel elements of nuclear boiling reactors. The concept states the importance of considering the ratio of heated channel perimeter to total channel perimeter. The perimeter ratio concept was arrived at from an experimental study of burnout conditions in rod clusters consisting of three rods of 13 mm outside diameter and 970 mm heated length. Data were obtained for pressures between{sub 2}. 5 and 10 kg/cm, surface heat fluxes between 50 and 120 W/cm, mass flow rates between 0.03 and 0.33 kg/sec and steam qualities between 0.01 and 0.52. The rod distances for the experiment were 2 mm and 6 mm. The diameter of the channel was 41.3 mm. Additional runs were also performed after introducing unheated displacement rods in the channel. The rod distance in this case was 6 mm. In the ranges investigated the measured burnout steam qualities at the outlet of the channel decreases with increasing heat flux and decreasing pressure. Furthermore it has been found that the influence of rod distance is, in the range investigated, of small significance for engineering purposes. It has also been observed that the present burnout steam quality data for the rod clusters are much lower than those earlier obtained for round ducts. This may be explained physically by means of the perimeter ratio concept. It has also been found that the surface shear-stress distribution around the channel perimeter and especially the position of maximum shear-stress is of great importance for predicting burnout conditions for flow in channels. Finally the new method has helped us to understand and interpret experimental results which earlier may have seemed inconsistent.

Burnout Conditions for Flow of Boiling Water in Vertical Rod Clusters

International Nuclear Information System (INIS)

Becker, Kurt M.

1962-05-01

This paper deals with a new concept for predicting burnout conditions for forced convection of boiling water in fuel elements of nuclear boiling reactors. The concept states the importance of considering the ratio of heated channel perimeter to total channel perimeter. The perimeter ratio concept was arrived at from an experimental study of burnout conditions in rod clusters consisting of three rods of 13 mm outside diameter and 970 mm heated length. Data were obtained for pressures between 2 . 5 and 10 kg/cm, surface heat fluxes between 50 and 120 W/cm, mass flow rates between 0.03 and 0.33 kg/sec and steam qualities between 0.01 and 0.52. The rod distances for the experiment were 2 mm and 6 mm. The diameter of the channel was 41.3 mm. Additional runs were also performed after introducing unheated displacement rods in the channel. The rod distance in this case was 6 mm. In the ranges investigated the measured burnout steam qualities at the outlet of the channel decreases with increasing heat flux and decreasing pressure. Furthermore it has been found that the influence of rod distance is, in the range investigated, of small significance for engineering purposes. It has also been observed that the present burnout steam quality data for the rod clusters are much lower than those earlier obtained for round ducts. This may be explained physically by means of the perimeter ratio concept. It has also been found that the surface shear-stress distribution around the channel perimeter and especially the position of maximum shear-stress is of great importance for predicting burnout conditions for flow in channels. Finally the new method has helped us to understand and interpret experimental results which earlier may have seemed inconsistent

Production and characterization of submicron hematite (α−Fe{sub 2}O{sub 3}) particles by ultrasonic spray pyrolysis method

Energy Technology Data Exchange (ETDEWEB)

Kırcı, Burak; Ebin, Burçak; Gürmen, Sebahattin [Department of Metallurgical and Materials Engineering, Istanbul Technical University Istanbul (Turkey)

2013-12-16

The ultrasonic spray pyrolysis (USP) method has been used to prepare submicron hematite (α−Fe{sub 2}O{sub 3}) particles using two different industrial pickling solutions of iron chloride (41 g/L FeCl{sub 2} and 54 g/L FeCl{sub 3}) Particles were obtained by thermal decomposition of generated aerosols from precursor solutions using 1.7 MHz ultrasonic atomizer. Reaction temperature was set up at 800 °C and aerosol droplets were carried into the heated zone by 0.7 L/min air flow rate. X-Ray Diffraction (XRD) studies were used to determine the crystal structure and crystallite size of the particles. Results indicate that patterns correspond to hematite phase with rhombohedral crystal structure (space group: R3c). The crystallite sizes of particles prepared from FeCl{sub 2} and FeCl{sub 3} solutions that were calculated from Scherrer equation are 59 and 33 nm, respectively. Scanning electron microscope (SEM) and energy dispersive spectroscopy (EDS) investigations give detailed information about particle size, morphology and composition. SEM micrographs show that hematite nanoparticles aggregate and formed spherical secondary particles in submicron range.

Size-selective separation of submicron particles in suspensions with ultrasonic atomization.

Science.gov (United States)

Nii, Susumu; Oka, Naoyoshi

2014-11-01

Aqueous suspensions containing silica or polystyrene latex were ultrasonically atomized for separating particles of a specific size. With the help of a fog involving fine liquid droplets with a narrow size distribution, submicron particles in a limited size-range were successfully separated from suspensions. Performance of the separation was characterized by analyzing the size and the concentration of collected particles with a high resolution method. Irradiation of 2.4MHz ultrasound to sample suspensions allowed the separation of particles of specific size from 90 to 320nm without regarding the type of material. Addition of a small amount of nonionic surfactant, PONPE20 to SiO2 suspensions enhanced the collection of finer particles, and achieved a remarkable increase in the number of collected particles. Degassing of the sample suspension resulted in eliminating the separation performance. Dissolved air in suspensions plays an important role in this separation. Copyright © 2014 Elsevier B.V. All rights reserved.

The total dose effects on the 1/f noise of deep submicron CMOS transistors

International Nuclear Information System (INIS)

Hu Rongbin; Wang Yuxin; Lu Wu

2014-01-01

Using 0.18 μm CMOS transistors, the total dose effects on the 1/f noise of deep-submicron CMOS transistors are studied for the first time in mainland China. From the experimental results and the theoretic analysis, we realize that total dose radiation causes a lot of trapped positive charges in STI (shallow trench isolation) SiO 2 layers, which induces a current leakage passage, increasing the 1/f noise power of CMOS transistors. In addition, we design some radiation-hardness structures on the CMOS transistors and the experimental results show that, until the total dose achieves 750 krad, the 1/f noise power of the radiation-hardness CMOS transistors remains unchanged, which proves our conclusion. (semiconductor devices)

Clustering of amines and hydrazines in atmospheric nucleation

Science.gov (United States)

Li, Siyang; Qu, Kun; Zhao, Hailiang; Ding, Lei; Du, Lin

2016-06-01

It has been proved that the presence of amines in the atmosphere can enhance aerosol formation. Hydrazine (HD) and its substituted derivatives, monomethylhydrazine (MMH) and unsymmetrical dimethylhydrazine (UDMH), which are organic derivatives of amine and ammonia, are common trace atmospheric species that may contribute to the growth of nucleation clusters. The structures of the hydrazine and amine clusters containing one or two common nucleation molecules (ammonia, water, methanol and sulfuric acid) have been optimized using density functional theory (DFT) methods. The clusters growth mechanism has been explored from the thermochemistry by calculating the Gibbs free energies of adding an ammonia, water, methanol or sulfuric acid molecule step by step at room temperature, respectively. The results show that hydrazine and its derivatives could enhance heteromolecular homogeneous nucleation in the earth's atmosphere.

Cluster Ions and Atmospheric Processes

Science.gov (United States)

D'Auria, R.; Turco, R. P.

We investigate the properties and possible roles of naturally occurring ions under at- mospheric conditions. Among other things, the formation of stable charged molecular clusters represents the initial stages of aerosol nucleation [e.g., Keesee and Castle- man, 1982], while the conversion of vapor to aggregates is the first step in certain atmospheric phase transitions [e.g. Hamill and Turco, 2000]. We analyze the stability and size distributions of common ionic clusters by solving the differential equations describing their growth and loss. The necessary reaction rate coefficients are deter- mined using kinetic and thermodynamic data. The latter are derived from direct labo- ratory measurements of equilibrium constants, from the classical charged liquid drop model applied to large aggregates (i.e., the Thomson model [Thomson, 1906]), and from quantum mechanical calculations of the thermodynamic potentials associated with the cluster structures. This approach allows us to characterize molecular clusters across the entire size range from true molecular species to larger aggregates exhibiting macroscopic behavior [D'Auria, 2001]. Cluster systems discussed in this talk include the proton hydrates (PHs) and nitrate-water and nitrate-nitric acid series [D'Auria and Turco, 2001]. These ions have frequently been detected in the stratosphere and tropo- sphere [e.g., Arnold et al., 1977; Viggiano and Arnold, 1981]. We show how the pro- posed hybrid cluster model can be extended to a wide range of ion systems, including non-proton hydrates (NPHs), mixed-ligand clusters such as nitrate-water-nitric acid and sulfate-sulfuric acid-water, as well as more exotic species containing ammonia, pyridine and other organic compounds found on ions [e.g., Eisele, 1988; Tanner and Eisele, 1991]. References: Arnold, F., D. Krankowsky and K. H. Marien, First mass spectrometric measurements of posi- tive ions in the stratosphere, Nature, 267, 30-32, 1977. D'Auria, R., A study of ionic

A facility for using cluster research to study environmental problems

International Nuclear Information System (INIS)

1991-11-01

This report begins by describing the general application of cluster based research to environmental chemistry and the development of a Cluster Structure and Dynamics Research Facility (CSDRF). Next, four important areas of cluster research are described in more detail, including how they can impact environmental problems. These are: surface-supported clusters, water and contaminant interactions, time-resolved dynamic studies in clusters, and cluster structures and reactions. These facilities and equipment required for each area of research are then presented. The appendices contain workshop agenda and a listing of the researchers who participated in the workshop discussions that led to this report

A facility for using cluster research to study environmental problems

Energy Technology Data Exchange (ETDEWEB)

1991-11-01

This report begins by describing the general application of cluster based research to environmental chemistry and the development of a Cluster Structure and Dynamics Research Facility (CSDRF). Next, four important areas of cluster research are described in more detail, including how they can impact environmental problems. These are: surface-supported clusters, water and contaminant interactions, time-resolved dynamic studies in clusters, and cluster structures and reactions. These facilities and equipment required for each area of research are then presented. The appendices contain workshop agenda and a listing of the researchers who participated in the workshop discussions that led to this report.

Rod cluster having improved vane configuration

International Nuclear Information System (INIS)

Shockling, L.A.; Francis, T.A.

1989-01-01

This patent describes a pressurized water reactor vessel, the vessel defining a predetermined axial direction of the flow of coolant therewithin and having plural spider assemblies supporting, for vertical movement within the vessel, respective clusters of rods in spaced, parallel axial relationship, parallel to the predetermined axial direction of coolant flow, and a rod guide for each spider assembly and respective cluster of rods. The rod guide having horizontally oriented support plates therewithin, each plate having an interior opening for accommodating axial movement therethrough of the spider assembly and respective cluster of rods. The opening defining plural radially extending channels and corresponding parallel interior wall surfaces of the support plate

Indoor and Outdoor Levels and Sources of Submicron Particles (PM1) at Homes in Edmonton, Canada.

Science.gov (United States)

Bari, Md Aynul; Kindzierski, Warren B; Wallace, Lance A; Wheeler, Amanda J; MacNeill, Morgan; Héroux, Marie-Ève

2015-06-02

Exposure to submicron particles (PM1) is of interest due to their possible chronic and acute health effects. Seven consecutive 24-h PM1 samples were collected during winter and summer 2010 in a total of 74 nonsmoking homes in Edmonton, Canada. Median winter concentrations of PM1 were 2.2 μg/m(3) (interquartile range, IQR = 0.8-6.1 μg/m(3)) and 3.3 μg/m(3) (IQR = 1.5-6.9 μg/m(3)) for indoors and outdoors, respectively. In the summer, indoor (median 4.4 μg/m(3), IQR = 2.4-8.6 μg/m(3)) and outdoor (median 4.3 μg/m(3), IQR = 2.6-7.4 μg/m(3)) levels were similar. Positive matrix factorization (PMF) was applied to identify and apportion indoor and outdoor sources of elements in PM1 mass. Nine sources contributing to both indoor and outdoor PM1 concentrations were identified including secondary sulfate, soil, biomass smoke and environmental tobacco smoke (ETS), traffic, settled and mixed dust, coal combustion, road salt/road dust, and urban mixture. Three additional indoor sources were identified i.e., carpet dust, copper-rich, and silver-rich. Secondary sulfate, soil, biomass smoke and ETS contributed more than 70% (indoors: 0.29 μg/m(3), outdoors: 0.39 μg/m(3)) of measured elemental mass in PM1. These findings can aid understanding of relationships between submicron particles and health outcomes for indoor/outdoor sources.

Statistical survey of the buried waters in the Protein Data Bank.

Science.gov (United States)

Carugo, Oliviero

2016-01-01

The structures of buried water molecules were studied in an ensemble of high-quality and non-redundant protein crystal structures. Buried water molecules were clustered and classified in lake-like clusters, which are completely isolated from the bulk solvent, and bay-like clusters, which are in contact with the bulk solvent through a surface water molecule. Buried water molecules are extremely common: lake-like clusters are found in 89 % of the protein crystal structures and bay-like clusters in 93 %. Clusters with only one water molecule are much more common than larger clusters. Both cluster types incline to be surrounded by loop residues, and to a minor extent by residues in extended secondary structure. Helical residues on the contrary do not tend to surround clusters of buried water molecules. One buried water molecule is found every 30-50 amino acid residues, depending on the secondary structures that are more abundant in the protein. Both main- and side-chain atoms are in contact with buried waters; they form four hydrogen bonds with the first water and 1-1.5 additional hydrogen bond for each additional water in the cluster. Consequently, buried water molecules appear to be firmly packed and rigid like the protein atoms. In this regard, it is remarkable to observe that prolines often surround water molecules buried in the protein interior. Interestingly, clusters of buried water molecules tend to be just beneath the protein surface. Moreover, water molecules tend to form a one-dimensional wire rather than more compact arrangements. This agrees with recent evidence of the mechanisms of solvent exchange between internal cavities and bulk solvent.

Modified two-step emulsion solvent evaporation technique for fabricating biodegradable rod-shaped particles in the submicron size range.

Science.gov (United States)

Safari, Hanieh; Adili, Reheman; Holinstat, Michael; Eniola-Adefeso, Omolola

2018-05-15

Though the emulsion solvent evaporation (ESE) technique has been previously modified to produce rod-shaped particles, it cannot generate small-sized rods for drug delivery applications due to the inherent coupling and contradicting requirements for the formation versus stretching of droplets. The separation of the droplet formation from the stretching step should enable the creation of submicron droplets that are then stretched in the second stage by manipulation of the system viscosity along with the surface-active molecule and oil-phase solvent. A two-step ESE protocol is evaluated where oil droplets are formed at low viscosity followed by a step increase in the aqueous phase viscosity to stretch droplets. Different surface-active molecules and oil phase solvents were evaluated to optimize the yield of biodegradable PLGA rods. Rods were assessed for drug loading via an imaging agent and vascular-targeted delivery application via blood flow adhesion assays. The two-step ESE method generated PLGA rods with major and minor axis down to 3.2 µm and 700 nm, respectively. Chloroform and sodium metaphosphate was the optimal solvent and surface-active molecule, respectively, for submicron rod fabrication. Rods demonstrated faster release of Nile Red compared to spheres and successfully targeted an inflamed endothelium under shear flow in vitro and in vivo. Copyright © 2018 Elsevier Inc. All rights reserved.

Measurements of Burnout Conditions for Flow of Boiling Water in Vertical 3-Rod and 7-Rod Clusters

International Nuclear Information System (INIS)

Becker, Kurt M.; Hernborg, G.; Flinta, J.E.

1964-08-01

The present report deals with measurements of burnout conditions for flow of boiling water in vertical 3-rod and 7-rod clusters. Data were obtained,in respect of heating the rods only, as well as for simultaneous uniform and non-uniform heating of the rods and the shroud. Totally, 520 runs were performed. In the case of equal heat fluxes on all surfaces of the channels, burnout always occurred on the rods, and the data were low by a factor of about 1.3 compared with round duct data. When only the rods were heated, the data showed very low burnout values in comparison with the results for total uniform heating and round ducts. This disagreement was explained by considering the climbing film flow model and the fact that only a fraction of the channel perimeter was heated. For simultaneous and non-uniform heating of the rods and the shroud it was found that the shroud could be overloaded up to 50 per cent without reducing the margin of safety in respect of burnout for the rod cluster. Finally, a correlation for predicting burnout conditions in round ducts, annuli and rod clusters has been presented. This correlation predicts the burnout heat fluxes for the present measurements and previously obtained annuli measurements within ± 5 per cent

Post-processing optimization of electrospun submicron poly(3-hydroxybutyrate) fibers to obtain continuous films of interest in food packaging applications.

Science.gov (United States)

Cherpinski, Adriane; Torres-Giner, Sergio; Cabedo, Luis; Lagaron, Jose M

2017-10-01

Polyhydroxyalkanoates (PHAs) are one of the most researched family of biodegradable polymers based on renewable materials due to their thermoplastic nature and moisture resistance. The present study was targeted to investigate the preparation and characterization of poly(3-hydroxybutyrate) (PHB) films obtained through the electrospinning technique. To convert them into continuous films and then to increase their application interest in packaging, the electrospun fiber mats were subsequently post-processed by different physical treatments. Thus, the effect of annealing time and cooling method on morphology, molecular order, thermal, optical, mechanical, and barrier properties of the electrospun submicron PHB fibers was studied. Annealing at 160°C, well below the homopolyester melting point, was found to be the minimum temperature at which homogeneous transparent films were produced. The film samples that were cooled slowly after annealing showed the lowest permeability to oxygen, water vapor, and limonene. The optimally post-processed electrospun PHB fibers exhibited similar rigidity to conventional compression-molded PHA films, but with enhanced elongation at break and toughness. Films made by this electrospinning technique have many potential applications, such as in the design of barrier layers, adhesive interlayers, and coatings for fiber- and plastic-based food packaging materials.

Innovative approach to produce submicron drug particles by vibrational atomization spray drying: influence of the type of solvent and surfactant.

Science.gov (United States)

Durli, T L; Dimer, F A; Fontana, M C; Pohlmann, A R; Beck, R C R; Guterres, S S

2014-08-01

Spray drying is a technique used to produce solid particles from liquid solutions, emulsions or suspensions. Buchi Labortechnik developed the latest generation of spray dryers, Nano Spray Dryer B-90. This study aims to obtain, directly, submicron drug particles from an organic solution, employing this equipment and using dexamethasone as a model drug. In addition, we evaluated the influence of both the type of solvent and surfactant on the properties of the powders using a 3(2) full factorial analysis. The particles were obtained with high yields (above 60%), low water content (below 2%) and high drug content (above 80%). The surface tension and the viscosity were strongly influenced by the type of solvent. The highest powder yields were obtained for the highest surface tension and the lowest viscosity of the drug solutions. The use of ionic surfactants led to higher process yields. The laser diffraction technique revealed that the particles deagglomerate into small ones with submicrometric size, (around 1 µm) that was also observed by scanning electron microscopy. Interaction between the raw materials in the spray-dried powders was verified by calorimetric analysis. Thus, it was possible to obtain dexamethasone submicrometric particles by vibrational atomization from organic solution.

Micro-scale Spatial Clustering of Cholera Risk Factors in Urban Bangladesh.

Science.gov (United States)

Bi, Qifang; Azman, Andrew S; Satter, Syed Moinuddin; Khan, Azharul Islam; Ahmed, Dilruba; Riaj, Altaf Ahmed; Gurley, Emily S; Lessler, Justin

2016-02-01

Close interpersonal contact likely drives spatial clustering of cases of cholera and diarrhea, but spatial clustering of risk factors may also drive this pattern. Few studies have focused specifically on how exposures for disease cluster at small spatial scales. Improving our understanding of the micro-scale clustering of risk factors for cholera may help to target interventions and power studies with cluster designs. We selected sets of spatially matched households (matched-sets) near cholera case households between April and October 2013 in a cholera endemic urban neighborhood of Tongi Township in Bangladesh. We collected data on exposures to suspected cholera risk factors at the household and individual level. We used intra-class correlation coefficients (ICCs) to characterize clustering of exposures within matched-sets and households, and assessed if clustering depended on the geographical extent of the matched-sets. Clustering over larger spatial scales was explored by assessing the relationship between matched-sets. We also explored whether different exposures tended to appear together in individuals, households, and matched-sets. Household level exposures, including: drinking municipal supplied water (ICC = 0.97, 95%CI = 0.96, 0.98), type of latrine (ICC = 0.88, 95%CI = 0.71, 1.00), and intermittent access to drinking water (ICC = 0.96, 95%CI = 0.87, 1.00) exhibited strong clustering within matched-sets. As the geographic extent of matched-sets increased, the concordance of exposures within matched-sets decreased. Concordance between matched-sets of exposures related to water supply was elevated at distances of up to approximately 400 meters. Household level hygiene practices were correlated with infrastructure shown to increase cholera risk. Co-occurrence of different individual level exposures appeared to mostly reflect the differing domestic roles of study participants. Strong spatial clustering of exposures at a small spatial scale in a cholera endemic

Micro-scale Spatial Clustering of Cholera Risk Factors in Urban Bangladesh.

Directory of Open Access Journals (Sweden)

Qifang Bi

2016-02-01

Full Text Available Close interpersonal contact likely drives spatial clustering of cases of cholera and diarrhea, but spatial clustering of risk factors may also drive this pattern. Few studies have focused specifically on how exposures for disease cluster at small spatial scales. Improving our understanding of the micro-scale clustering of risk factors for cholera may help to target interventions and power studies with cluster designs. We selected sets of spatially matched households (matched-sets near cholera case households between April and October 2013 in a cholera endemic urban neighborhood of Tongi Township in Bangladesh. We collected data on exposures to suspected cholera risk factors at the household and individual level. We used intra-class correlation coefficients (ICCs to characterize clustering of exposures within matched-sets and households, and assessed if clustering depended on the geographical extent of the matched-sets. Clustering over larger spatial scales was explored by assessing the relationship between matched-sets. We also explored whether different exposures tended to appear together in individuals, households, and matched-sets. Household level exposures, including: drinking municipal supplied water (ICC = 0.97, 95%CI = 0.96, 0.98, type of latrine (ICC = 0.88, 95%CI = 0.71, 1.00, and intermittent access to drinking water (ICC = 0.96, 95%CI = 0.87, 1.00 exhibited strong clustering within matched-sets. As the geographic extent of matched-sets increased, the concordance of exposures within matched-sets decreased. Concordance between matched-sets of exposures related to water supply was elevated at distances of up to approximately 400 meters. Household level hygiene practices were correlated with infrastructure shown to increase cholera risk. Co-occurrence of different individual level exposures appeared to mostly reflect the differing domestic roles of study participants. Strong spatial clustering of exposures at a small spatial scale in a

The atomic structure of transition metal clusters

International Nuclear Information System (INIS)

Riley, S.J.

1995-01-01

Chemical reactions are used to probe the atomic (geometrical) structure of isolated clusters of transition metal atoms. The number of adsorbate molecules that saturate a cluster, and/or the binding energy of molecules to cluster surfaces, are determined as a function of cluster size. Systematics in these properties often make it possible to propose geometrical structures consistent with the experimental observations. We will describe how studies of the reactions of cobalt and nickel clusters with ammonia, water, and nitrogen provide important and otherwise unavailable structural information. Specifically, small (less than 20 atoms) clusters of cobalt and nickel atoms adopt entirely different structures, the former having packing characteristic of the bulk and the latter having pentagonal symmetry. These observations provide important input for model potentials that attempt to describe the local properties of transition metals. In particular, they point out the importance of a proper treatment of d-orbital binding in these systems, since cobalt and nickel differ so little in their d-orbital occupancy

Enhanced Etching, Surface Damage Recovery, and Submicron Patterning of Hybrid Perovskites using a Chemically Gas-Assisted Focused-Ion Beam for Subwavelength Grating Photonic Applications

KAUST Repository

Alias, Mohd Sharizal

2015-12-22

The high optical gain and absorption of organic–inorganic hybrid perovskites have attracted attention for photonic device applications. However, owing to the sensitivity of organic moieties to solvents and temperature, device processing is challenging, particularly for patterning. Here, we report the direct patterning of perovskites using chemically gas-assisted focused-ion beam (GAFIB) etching with XeF2 and I2 precursors. We demonstrate etching enhancement in addition to controllability and marginal surface damage compared to focused-ion beam (FIB) etching without precursors. Utilizing the GAFIB etching, we fabricated a uniform and periodic submicron perovskite subwavelength grating (SWG) absorber with broadband absorption and nanoscale precision. Our results demonstrate the use of FIB as a submicron patterning tool and a means of providing surface treatment (after FIB patterning to minimize optical loss) for perovskite photonic nanostructures. The SWG absorber can be patterned on perovskite solar cells to enhance the device efficiency through increasing light trapping and absorption.

Hand washing with soap and water together with behavioural recommendations prevents infections in common work environment: an open cluster-randomized trial.

Science.gov (United States)

Savolainen-Kopra, Carita; Haapakoski, Jaason; Peltola, Piia A; Ziegler, Thedi; Korpela, Terttu; Anttila, Pirjo; Amiryousefi, Ali; Huovinen, Pentti; Huvinen, Markku; Noronen, Heikki; Riikkala, Pia; Roivainen, Merja; Ruutu, Petri; Teirilä, Juha; Vartiainen, Erkki; Hovi, Tapani

2012-01-16

Hand hygiene is considered as an important means of infection control. We explored whether guided hand hygiene together with transmission-limiting behaviour reduces infection episodes and lost days of work in a common work environment in an open cluster-randomized 3-arm intervention trial. A total of 21 clusters (683 persons) were randomized to implement hand hygiene with soap and water (257 persons), with alcohol-based hand rub (202 persons), or to serve as a control (224 persons). Participants in both intervention arms also received standardized instructions on how to limit the transmission of infections. The intervention period (16 months) included the emergence of the 2009 influenza pandemic and the subsequent national hand hygiene campaign influencing also the control arm. In the total follow-up period there was a 6.7% reduction of infection episodes in the soap-and water arm (p = 0.04). Before the onset of the anti-pandemic campaign, a statistically significant (p = 0.002) difference in the mean occurrence of infection episodes was observed between the control (6.0 per year) and the soap-and-water arm (5.0 per year) but not between the control and the alcohol-rub arm (5.6 per year). Neither intervention had a decreasing effect on absence from work. We conclude that intensified hand hygiene using water and soap together with behavioural recommendations can reduce the occurrence of self-reported acute illnesses in common work environment. Surprisingly, the occurrence of reported sick leaves also increased in the soap-and water-arm. ClinicalTrials.gov: NCT00981877 The Finnish Work Environment Fund and the National Institute for Health and Welfare.

Picking a Fight with Water, and Water Lost ... an Electron

Science.gov (United States)

Herr, Jonathan D.

The global need for energy is increasing, as is the importance of producing energy by green and renewable methodologies. This document outlines a research program dedicated to investigating a possible source for this form of energy generation and storage: solar fuels. The photon-induced splitting of water into molecular hydrogen and oxygen is currently hindered by large overpotentials from the oxidation half-reaction of water-splitting. This study concentrated on fundamental models of water-spitting chemistry, using a physical and computational chemistry analysis. The oxidation was first explored via ab initio electronic structure calculations of bare cationic water clusters, comprised of 2 to 21 molecules, in order to determine key electronic interactions that facilitate oxidation. Deeper understanding of these interactions could serve as guides for the development of viable water oxidation catalysts (WOC) designed to reduce overpotentials. The cationic water cluster study was followed by an investigation into hydrated copper (I) clusters, which acted as precursor models for real WOCs. Analyzing how the copper ion perturbed the properties of water clusters led to important electronic considerations for the development of WOCs, such as copper-water interactions that go beyond simple electrostatics. The importance of diagnostic thermodynamic properties, as well as anharmonic characteristics being persistent throughout oxidized water clusters, necessitated the use of quantum and classical molecular dynamics (MD) routines. Therefore, two new methods for accelerating computationally demanding classical and quantum MD methods were developed to increase their accessibility. The first method utilized a new form of electronic extrapolation - a linear prediction routine incorporating a Burg minimization - to decrease the iterations required for solving the electronic equations throughout the dynamics. The second method utilized a multiple-timestepping description of the

Cooperative protein structural dynamics of homodimeric hemoglobin linked to water cluster at subunit interface revealed by time-resolved X-ray solution scattering

Directory of Open Access Journals (Sweden)

Jong Goo Kim

2016-03-01

Full Text Available Homodimeric hemoglobin (HbI consisting of two subunits is a good model system for investigating the allosteric structural transition as it exhibits cooperativity in ligand binding. In this work, as an effort to extend our previous study on wild-type and F97Y mutant HbI, we investigate structural dynamics of a mutant HbI in solution to examine the role of well-organized interfacial water cluster, which has been known to mediate intersubunit communication in HbI. In the T72V mutant of HbI, the interfacial water cluster in the T state is perturbed due to the lack of Thr72, resulting in two less interfacial water molecules than in wild-type HbI. By performing picosecond time-resolved X-ray solution scattering experiment and kinetic analysis on the T72V mutant, we identify three structurally distinct intermediates (I1, I2, and I3 and show that the kinetics of the T72V mutant are well described by the same kinetic model used for wild-type and F97Y HbI, which involves biphasic kinetics, geminate recombination, and bimolecular CO recombination. The optimized kinetic model shows that the R-T transition and bimolecular CO recombination are faster in the T72V mutant than in the wild type. From structural analysis using species-associated difference scattering curves for the intermediates, we find that the T-like deoxy I3 intermediate in solution has a different structure from deoxy HbI in crystal. In addition, we extract detailed structural parameters of the intermediates such as E-F distance, intersubunit rotation angle, and heme-heme distance. By comparing the structures of protein intermediates in wild-type HbI and the T72V mutant, we reveal how the perturbation in the interfacial water cluster affects the kinetics and structures of reaction intermediates of HbI.

Sub-micron resolution selected area electron channeling patterns.

Science.gov (United States)

Guyon, J; Mansour, H; Gey, N; Crimp, M A; Chalal, S; Maloufi, N

2015-02-01

Collection of selected area channeling patterns (SACPs) on a high resolution FEG-SEM is essential to carry out quantitative electron channeling contrast imaging (ECCI) studies, as it facilitates accurate determination of the crystal plane normal with respect to the incident beam direction and thus allows control the electron channeling conditions. Unfortunately commercial SACP modes developed in the past were limited in spatial resolution and are often no longer offered. In this contribution we present a novel approach for collecting high resolution SACPs (HR-SACPs) developed on a Gemini column. This HR-SACP technique combines the first demonstrated sub-micron spatial resolution with high angular accuracy of about 0.1°, at a convenient working distance of 10mm. This innovative approach integrates the use of aperture alignment coils to rock the beam with a digitally calibrated beam shift procedure to ensure the rocking beam is maintained on a point of interest. Moreover a new methodology to accurately measure SACP spatial resolution is proposed. While column considerations limit the rocking angle to 4°, this range is adequate to index the HR-SACP in conjunction with the pattern simulated from the approximate orientation deduced by EBSD. This new technique facilitates Accurate ECCI (A-ECCI) studies from very fine grained and/or highly strained materials. It offers also new insights for developing HR-SACP modes on new generation high-resolution electron columns. Copyright © 2014 Elsevier B.V. All rights reserved.

Investigations into the penetration and pressure drop of HEPA filter media during loading with submicron particle aerosols at high concentrations

International Nuclear Information System (INIS)

Leibold, H; Wilhelm, J.G.

1991-01-01

High Efficiency Particulate Air (HEPA) filters are typically employed in particle removal and retention within the air cleaning systems of clean rooms in the pharmaceutical, nuclear and semiconductor industries for dust concentrations of some μg/m 3 . Their extremely high removal efficiencies for submicron particles make them attractive candidates in complying with increasingly lower emission limits for industrial processes that involve dust concentrations of up to several g/m 3 . Cost-effective operation under such conditions requires the filter units to be recleanable. The recleanability of HEPA filter media depends not only on the operating conditions during the cleaning process but also on the filtration conditions during particle loading. The structure and location of the particles captured by the glass fiber matrix greatly affect the degree to which they can be subsequently dislodged and removed from the filter medium. Changes in filtration efficiency with service time for various particle diameters in the critical submicron size range, as well as the effects of filtration velocity on the increase in pressure drop, are important criteria with regard to recleaning HEPA filter units. Of special significance for the recleanability of HEPA filter media is knowledge of how operating conditions affect dust cake formation. (author)

Effect of water quality, sanitation, hand washing, and nutritional interventions on child development in rural Bangladesh (WASH Benefits Bangladesh): a cluster-randomised controlled trial.

Science.gov (United States)

Tofail, Fahmida; Fernald, Lia Ch; Das, Kishor K; Rahman, Mahbubur; Ahmed, Tahmeed; Jannat, Kaniz K; Unicomb, Leanne; Arnold, Benjamin F; Ashraf, Sania; Winch, Peter J; Kariger, Patricia; Stewart, Christine P; Colford, John M; Luby, Stephen P

2018-04-01

Poor nutrition and hygiene make children vulnerable to delays in growth and development. We aimed to assess the effects of water quality, sanitation, handwashing, and nutritional interventions individually or in combination on the cognitive, motor, and language development of children in rural Bangladesh. In this cluster-randomised controlled trial, we enrolled pregnant women in their first or second trimester from rural villages of Gazipur, Kishoreganj, Mymensingh, and Tangail districts of central Bangladesh, with an average of eight women per cluster. Groups of eight geographically adjacent clusters were block-randomised, using a random number generator, into six intervention groups (all of which received weekly visits from a community health promoter for the first 6 months and every 2 weeks for the next 18 months) and a double-sized control group (no intervention or health promoter visit). The six intervention groups were: chlorinated drinking water; improved sanitation; handwashing with soap; combined water, sanitation, and handwashing; improved nutrition through counselling and provision of lipid-based nutrient supplements; and combined water, sanitation, handwashing, and nutrition. Here, we report on the prespecified secondary child development outcomes: gross motor milestone achievement assessed with the WHO module at age 1 year, and communication, gross motor, personal social, and combined scores measured by the Extended Ages and Stages Questionnaire (EASQ) at age 2 years. Masking of participants was not possible. Analyses were by intention to treat. This trial is registered with ClinicalTrials.gov, number NCT01590095. Between May 31, 2012, and July 7, 2013, 5551 pregnant women residing in 720 clusters were enrolled. Index children of 928 (17%) enrolled women were lost to follow-up in year 1 and an additional 201 (3%) in year 2. 4757 children were assessed at 1 year and 4403 at 2 years. At year 1, compared with the control group, the combined water

Assessment of water quality in the elbe river at flood water conditions based on cluster analysis, principle components analysis, and source apportionment

Energy Technology Data Exchange (ETDEWEB)

Baborowski, Martina [Department of River Ecology, UFZ-Helmholtz Centre for Environmental Research, Magdeburg (Germany); Simeonov, Vasil [Faculty of Chemistry, University of Sofia, Sofia (Bulgaria); Einax, Juergen W. [Institute of Inorganic and Analytical Chemistry, Friedrich Schiller University of Jena, Jena (Germany)

2012-04-15

An assessment of water quality measurements during a spring flood in the Elbe River is presented. Daily samples were taken at a site in the middle Elbe, which is part of the network of the International Commission for the Protection of the Elbe River (IKSE/MKOL). Cluster analysis (CA), principal components analysis (PCA), and source apportionment (APCS apportioning) were used to assess the flood-dependent matter transport. As a result, three main components could be extracted as important to the matter transport in the Elbe River basin during flood events: (i) re-suspended contaminated sediments, which led to temporarily increased concentrations of suspended matter and of most of the investigated heavy metals; (ii) water discharge related concentrations of pedogenic dissolved organic matter (DOM) as well as preliminary diluted concentrations of uranium and chloride, parameters with stable pollution background in the river basin; and (iii) abandoned mines, i.e., their dewatering systems, with particular influence on nickel, manganese, and zinc concentrations. (Copyright copyright 2012 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

Assessment of water quality in the elbe river at flood water conditions based on cluster analysis, principle components analysis, and source apportionment

International Nuclear Information System (INIS)

Baborowski, Martina; Simeonov, Vasil; Einax, Juergen W.

2012-01-01

An assessment of water quality measurements during a spring flood in the Elbe River is presented. Daily samples were taken at a site in the middle Elbe, which is part of the network of the International Commission for the Protection of the Elbe River (IKSE/MKOL). Cluster analysis (CA), principal components analysis (PCA), and source apportionment (APCS apportioning) were used to assess the flood-dependent matter transport. As a result, three main components could be extracted as important to the matter transport in the Elbe River basin during flood events: (i) re-suspended contaminated sediments, which led to temporarily increased concentrations of suspended matter and of most of the investigated heavy metals; (ii) water discharge related concentrations of pedogenic dissolved organic matter (DOM) as well as preliminary diluted concentrations of uranium and chloride, parameters with stable pollution background in the river basin; and (iii) abandoned mines, i.e., their dewatering systems, with particular influence on nickel, manganese, and zinc concentrations. (Copyright copyright 2012 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

Effects of water quality, sanitation, handwashing, and nutritional interventions on diarrhoea and child growth in rural Kenya: a cluster-randomised controlled trial

Directory of Open Access Journals (Sweden)

Clair Null, PhD

2018-03-01

Full Text Available Summary: Background: Poor nutrition and exposure to faecal contamination are associated with diarrhoea and growth faltering, both of which have long-term consequences for child health. We aimed to assess whether water, sanitation, handwashing, and nutrition interventions reduced diarrhoea or growth faltering. Methods: The WASH Benefits cluster-randomised trial enrolled pregnant women from villages in rural Kenya and evaluated outcomes at 1 year and 2 years of follow-up. Geographically-adjacent clusters were block-randomised to active control (household visits to measure mid-upper-arm circumference, passive control (data collection only, or compound-level interventions including household visits to promote target behaviours: drinking chlorinated water (water; safe sanitation consisting of disposing faeces in an improved latrine (sanitation; handwashing with soap (handwashing; combined water, sanitation, and handwashing; counselling on appropriate maternal, infant, and young child feeding plus small-quantity lipid-based nutrient supplements from 6–24 months (nutrition; and combined water, sanitation, handwashing, and nutrition. Primary outcomes were caregiver-reported diarrhoea in the past 7 days and length-for-age Z score at year 2 in index children born to the enrolled pregnant women. Masking was not possible for data collection, but analyses were masked. Analysis was by intention to treat. This trial is registered with ClinicalTrials.gov, number NCT01704105. Findings: Between Nov 27, 2012, and May 21, 2014, 8246 women in 702 clusters were enrolled and randomly assigned an intervention or control group. 1919 women were assigned to the active control group; 938 to passive control; 904 to water; 892 to sanitation; 917 to handwashing; 912 to combined water, sanitation, and handwashing; 843 to nutrition; and 921 to combined water, sanitation, handwashing, and nutrition. Data on diarrhoea at year 1 or year 2 were available for 6494 children and

Quantum chemical analysis of thermodynamics of 2D cluster formation of alkanes at the water/vapor interface in the presence of aliphatic alcohols.

Science.gov (United States)

Vysotsky, Yu B; Kartashynska, E S; Belyaeva, E A; Fainerman, V B; Vollhardt, D; Miller, R

2015-11-21

Using the quantum chemical semi-empirical PM3 method it is shown that aliphatic alcohols favor the spontaneous clusterization of vaporous alkanes at the water surface due to the change of adsorption from the barrier to non-barrier mechanism. A theoretical model of the non-barrier mechanism for monolayer formation is developed. In the framework of this model alcohols (or any other surfactants) act as 'floats', which interact with alkane molecules of the vapor phase using their hydrophobic part, whereas the hydrophilic part is immersed into the water phase. This results in a significant increase of contact effectiveness of alkanes with the interface during the adsorption and film formation. The obtained results are in good agreement with the existing experimental data. To test the model the thermodynamic and structural parameters of formation and clusterization are calculated for vaporous alkanes C(n)H(2n+2) (n(CH3) = 6-16) at the water surface in the presence of aliphatic alcohols C(n)H(2n+1)OH (n(OH) = 8-16) at 298 K. It is shown that the values of clusterization enthalpy, entropy and Gibbs' energy per one monomer of the cluster depend on the chain lengths of corresponding alcohols and alkanes, the alcohol molar fraction in the monolayers formed, and the shift of the alkane molecules with respect to the alcohol molecules Δn. Two possible competitive structures of mixed 2D film alkane-alcohol are considered: 2D films 1 with single alcohol molecules enclosed by alkane molecules (the alcohols do not form domains) and 2D films 2 that contain alcohol domains enclosed by alkane molecules. The formation of the alkane films of the first type is nearly independent of the surfactant type present at the interface, but depends on their molar fraction in the monolayer formed and the chain length of the compounds participating in the clusterization, whereas for the formation of the films of the second type the interaction between the hydrophilic parts of the surfactant is

Investigating the significance of zero-point motion in small molecular clusters of sulphuric acid and water

International Nuclear Information System (INIS)

Stinson, Jake L.; Ford, Ian J.; Kathmann, Shawn M.

2014-01-01

The nucleation of particles from trace gases in the atmosphere is an important source of cloud condensation nuclei, and these are vital for the formation of clouds in view of the high supersaturations required for homogeneous water droplet nucleation. The methods of quantum chemistry have increasingly been employed to model nucleation due to their high accuracy and efficiency in calculating configurational energies; and nucleation rates can be obtained from the associated free energies of particle formation. However, even in such advanced approaches, it is typically assumed that the nuclei have a classical nature, which is questionable for some systems. The importance of zero-point motion (also known as quantum nuclear dynamics) in modelling small clusters of sulphuric acid and water is tested here using the path integral molecular dynamics method at the density functional level of theory. The general effect of zero-point motion is to distort the mean structure slightly, and to promote the extent of proton transfer with respect to classical behaviour. In a particular configuration of one sulphuric acid molecule with three waters, the range of positions explored by a proton between a sulphuric acid and a water molecule at 300 K (a broad range in contrast to the confinement suggested by geometry optimisation at 0 K) is clearly affected by the inclusion of zero point motion, and similar effects are observed for other configurations

Electronic structures and water reactivity of mixed metal sulfide cluster anions

Energy Technology Data Exchange (ETDEWEB)

Saha, Arjun; Raghavachari, Krishnan [Department of Chemistry, Indiana University, Bloomington, Indiana 47405 (United States)

2014-08-21

The electronic structures and chemical reactivity of the mixed metal sulfide cluster anion (MoWS{sub 4}{sup −}) have been investigated with density functional theory. Our study reveals the presence of two almost isoenergetic structural isomers, both containing two bridging sulfur atoms in a quartet state. However, the arrangement of the terminal sulfur atoms is different in the two isomers. In one isomer, the two metals are in the same oxidation state (each attached to one terminal S). In the second isomer, the two metals are in different oxidation states (with W in the higher oxidation state attached to both terminal S). The reactivity of water with the two lowest energy isomers has also been studied, with an emphasis on pathways leading to H{sub 2} release. The reactive behavior of the two isomers is different though the overall barriers in both systems are small. The origin of the differences are analyzed and discussed. The reaction pathways and barriers are compared with the corresponding behavior of monometallic sulfides (Mo{sub 2}S{sub 4}{sup −} and W{sub 2}S{sub 4}{sup −}) as well as mixed metal oxides (MoWO{sub 4}{sup −})

Toward Quantifying the Mass-Based Hygroscopicity of Individual Submicron Atmospheric Aerosol Particles with STXM/NEXAFS and SEM/EDX

Science.gov (United States)

Yancey Piens, D.; Kelly, S. T.; OBrien, R. E.; Wang, B.; Petters, M. D.; Laskin, A.; Gilles, M. K.

2014-12-01

The hygroscopic behavior of atmospheric aerosols influences their optical and cloud-nucleation properties, and therefore affects climate. Although changes in particle size as a function of relative humidity have often been used to quantify the hygroscopic behavior of submicron aerosol particles, it has been noted that calculations of hygroscopicity based on size contain error due to particle porosity, non-ideal volume additivity and changes in surface tension. We will present a method to quantify the hygroscopic behavior of submicron aerosol particles based on changes in mass, rather than size, as a function of relative humidity. This method results from a novel experimental approach combining scanning transmission x-ray microscopy with near-edge x-ray absorption fine spectroscopy (STXM/NEXAFS), as well as scanning electron microscopy with energy dispersive x-ray spectroscopy (SEM/EDX) on the same individual particles. First, using STXM/NEXAFS, our methods are applied to aerosol particles of known composition ‒ for instance ammonium sulfate, sodium bromide and levoglucosan ‒ and validated by theory. Then, using STXM/NEXAFS and SEM/EDX, these methods are extended to mixed atmospheric aerosol particles collected in the field at the DOE Atmospheric Radiation Measurement (ARM) Climate Research Facility at the Southern Great Planes sampling site in Oklahoma, USA. We have observed and quantified a range of hygroscopic behaviors which are correlated to the composition and morphology of individual aerosol particles. These methods will have implications for parameterizing aerosol mixing state and cloud-nucleation activity in atmospheric models.

Development of Pixel Front-End Electronics using Advanced Deep Submicron CMOS Technologies

CERN Document Server

Havránek, Miroslav; Dingfelder, Jochen

The content of this thesis is oriented on the R&D; of microelectronic integrated circuits for processing the signal from particle sensors and partially on the sensors themselves. This work is motivated by ongoing upgrades of the ATLAS Pixel Detector at CERN laboratory and by exploration of new technologies for the future experiments in particle physics. Evolution of technologies for the fabrication of microelectronic circuits follows Moore’s laws. Transistors become smaller and electronic chips reach higher complexity. Apart from this, silicon foundries become more open to smaller customers and often provide non-standard process options. Two new directions in pixel technologies are explored in this thesis: design of pixel electronics using ultra deep submicron (65 nm) CMOS technology and Depleted Monolithic Active Pixel Sensors (DMAPS). An independent project concerning the measurement of pixel capacitance with a dedicated measurement chip is a part of this thesis. Pixel capacitance is one of the key pa...

Photonic bandpass filter characteristics of multimode SOI waveguides integrated with submicron gratings.

Science.gov (United States)

Sah, Parimal; Das, Bijoy Krishna

2018-03-20

It has been shown that a fundamental mode adiabatically launched into a multimode SOI waveguide with submicron grating offers well-defined flat-top bandpass filter characteristics in transmission. The transmitted spectral bandwidth is controlled by adjusting both waveguide and grating design parameters. The bandwidth is further narrowed down by cascading two gratings with detuned parameters. A semi-analytical model is used to analyze the filter characteristics (1500  nm≤λ≤1650  nm) of the device operating in transverse-electric polarization. The proposed devices were fabricated with an optimized set of design parameters in a SOI substrate with a device layer thickness of 250 nm. The pass bandwidth of waveguide devices integrated with single-stage gratings are measured to be ∼24  nm, whereas the device with two cascaded gratings with slightly detuned periods (ΔΛ=2  nm) exhibits a pass bandwidth down to ∼10  nm.

Study of pressure losses in the EL 4 cluster

International Nuclear Information System (INIS)

Berriaud, Ch.

1964-01-01

The evolution of research on the EL-4 cluster is examined here from the pressure losses point of view. These may be split up into separate pressure losses along the rode and in pressure losses corresponding to various particularities of the cluster. Tests have been carried out on series of three or four clusters placed in a channel. Water was first used, and then carbon dioxide at 60 bars. In all cases the following two parameters were varied: the Reynolds' number, and the rotation of a cluster around its axis with respect to the surrounding clusters. The influence of the gap between to successive clusters has also been studied. The first tests were carried out on clusters without jackets, the subsequent ones on clusters fitted with jackets. It was thus possible to study various types of element assemblies. The results are given in the form of curves representing: the evolution of the independent pressure loss coefficients as a function of the Reynolds number. (author) [fr

Superhydrophobic polytetrafluoroethylene thin films with hierarchical roughness deposited using a single step vapor phase technique

International Nuclear Information System (INIS)

Gupta, Sushant; Arjunan, Arul Chakkaravarthi; Deshpande, Sameer; Seal, Sudipta; Singh, Deepika; Singh, Rajiv K.

2009-01-01

Superhydrophobic polytetrafluoroethylene films with hierarchical surface roughness were deposited using pulse electron deposition technique. We were able to modulate roughness of the deposited films by controlling the beam energy and hence the electron penetration depth. The films deposited at higher beam energy showed contact angle as high as 166 o . The scanning electron and atomic force microscope studies revealed clustered growth and two level sub-micron asperities on films deposited at higher energies. Such dual-scale hierarchical roughness and heterogeneities at the water-surface interface was attributed to the observed contact angle and thus its superhydrophobic nature.

Superhydrophobic polytetrafluoroethylene thin films with hierarchical roughness deposited using a single step vapor phase technique

Energy Technology Data Exchange (ETDEWEB)

Gupta, Sushant, E-mail: sushant3@ufl.ed [Department of Materials Science and Engineering, University of Florida, Gainesville, FL 32611 (United States); Arjunan, Arul Chakkaravarthi [Sinmat Incorporated, 2153 SE Hawthorne Road, 129, Gainesville, Florida 32641 (United States); Deshpande, Sameer; Seal, Sudipta [Advanced Material Processing and Analysis Center, University of Central Florida, Orlando, Florida 32816 (United States); Singh, Deepika [Sinmat Incorporated, 2153 SE Hawthorne Road, 129, Gainesville, Florida 32641 (United States); Singh, Rajiv K. [Department of Materials Science and Engineering, University of Florida, Gainesville, FL 32611 (United States)

2009-06-30

Superhydrophobic polytetrafluoroethylene films with hierarchical surface roughness were deposited using pulse electron deposition technique. We were able to modulate roughness of the deposited films by controlling the beam energy and hence the electron penetration depth. The films deposited at higher beam energy showed contact angle as high as 166{sup o}. The scanning electron and atomic force microscope studies revealed clustered growth and two level sub-micron asperities on films deposited at higher energies. Such dual-scale hierarchical roughness and heterogeneities at the water-surface interface was attributed to the observed contact angle and thus its superhydrophobic nature.

Hand washing with soap and water together with behavioural recommendations prevents infections in common work environment: an open cluster-randomized trial

Directory of Open Access Journals (Sweden)

Savolainen-Kopra Carita

2012-01-01

Full Text Available Abstract Background Hand hygiene is considered as an important means of infection control. We explored whether guided hand hygiene together with transmission-limiting behaviour reduces infection episodes and lost days of work in a common work environment in an open cluster-randomized 3-arm intervention trial. Methods A total of 21 clusters (683 persons were randomized to implement hand hygiene with soap and water (257 persons, with alcohol-based hand rub (202 persons, or to serve as a control (224 persons. Participants in both intervention arms also received standardized instructions on how to limit the transmission of infections. The intervention period (16 months included the emergence of the 2009 influenza pandemic and the subsequent national hand hygiene campaign influencing also the control arm. Results In the total follow-up period there was a 6.7% reduction of infection episodes in the soap-and water arm (p = 0.04. Before the onset of the anti-pandemic campaign, a statistically significant (p = 0.002 difference in the mean occurrence of infection episodes was observed between the control (6.0 per year and the soap-and-water arm (5.0 per year but not between the control and the alcohol-rub arm (5.6 per year. Neither intervention had a decreasing effect on absence from work. Conclusions We conclude that intensified hand hygiene using water and soap together with behavioural recommendations can reduce the occurrence of self-reported acute illnesses in common work environment. Surprisingly, the occurrence of reported sick leaves also increased in the soap-and water-arm. Trial Registration ClinicalTrials.gov: NCT00981877 Source of funding The Finnish Work Environment Fund and the National Institute for Health and Welfare.

On the use of ultrafiltration membranes in oily water separators

Energy Technology Data Exchange (ETDEWEB)

Tremblay, A.Y.; Nottegar, M. [Ottawa Univ., ON (Canada). Dept. of Chemical Engineering; Veinot, D.E. [Defence Research Establishment Atlantic, Halifax, NS (Canada)

2000-07-01

Laboratory studies were conducted on the use of ultrafiltration membranes for oil water purification from ships bilges. Bilge water is a complex and highly variable mixture of several components such as seawater, lubricating oil, greases, marine diesel fuel, hydraulic oil, detergents, metal oxides, corrosion inhibitors, asbestos and other wastes. This laboratory study examined the performance of ultrafiltration membranes when separating oily waste water of similar composition to that of bilge water. Ultrafiltration membranes are nanoporous materials produced from ceramic, polymeric or metallic substrates. The ability of the membrane to retain macromolecules, colloids, sub-micron particles and oil emulsions depends on the size of the nanopores. The best results in this study occurred when upper and lower bounds on the membrane pore size were found to exist. It was determined that ultrafiltration is a viable separation process for the treatment of bilge water for compliance with overboard discharge regulations. 7 refs., 1 tab., 3 figs.

Transportation: Grade 8. Cluster IV.

Science.gov (United States)

Calhoun, Olivia H.

A curriculum guide for grade 8, the document is devoted to the occupational cluster "Transportation." It is divided into five units: surface transportation, interstate transportation, air transportation, water transportation, and subterranean transportation (the Metro). Each unit is introduced by a statement of the topic, the unit's…

Solvation in supercritical water

International Nuclear Information System (INIS)

Cochran, H.D.; Cummings, P.T.; Karaborni, S.

1991-01-01

The aim of this work is to determine the solvation structure in supercritical water composed with that in ambient water and in simple supercritical solvents. Molecular dynamics studies have been undertaken of systems that model ionic sodium and chloride, atomic argon, and molecular methanol in supercritical aqueous solutions using the simple point charge model of Berendsen for water. Because of the strong interactions between water and ions, ionic solutes are strongly attractive in supercritical water, forming large clusters of water molecules around each ion. Methanol is found to be a weakly-attractive solute in supercritical water. The cluster of excess water molecules surrounding a dissolved ion or polar molecule in supercritical aqueous solutions is comparable to the solvent clusters surrounding attractive solutes in simple supercritical fluids. Likewise, the deficit of water molecules surrounding a dissolved argon atom in supercritical aqueous solutions is comparable to that surrounding repulsive solutes in simple supercritical fluids. The number of hydrogen bonds per water molecule in supercritical water was found to be about one third the number in ambient water. The number of hydrogen bonds per water molecule surrounding a central particle in supercritical water was only mildly affected by the identify of the central particle--atom, molecule, or ion. These results should be helpful in developing a qualitative understanding of important processes that occur in supercritical water. 29 refs., 6 figs

Calculation of the thermal and hydraulic states in rod cluster cores of light-water reactors

International Nuclear Information System (INIS)

Teichel, H.

1977-01-01

For calculating the three-dimensional steady distribution of the thermal and hydraulic states in rod cluster cores of light-water reactors, the subchannel analysis programs COLA 1 and COLA 2 have been developed. Both programs contain a multitude of competing empirical correlations which may be used by choice. The programs COLA 1 and COLA 2 differ in the calculation method and in the treatment of the boundary condition 'equal pressure at the end of all cooling channels' governing the problem. All parts of the programs are identical. By means of recomputed experiments statements on the accuracy of the results to be expected can be made. In addition, the different suitability of both programs for different experimental conditions are shown. (orig.) [de

Production of solid lipid submicron particles for protein delivery using a novel supercritical gas-assisted melting atomization process.

Science.gov (United States)

Salmaso, Stefano; Elvassore, Nicola; Bertucco, Alberto; Caliceti, Paolo

2009-02-01

A supercritical carbon dioxide micronization technique based on gas-assisted melting atomization has been designed to prepare protein-loaded solid lipid submicron particles. The supercritical process was applied to homogeneous dispersions of insulin in lipid mixtures: (1) tristearin, Tween-80, phosphatidylcholine and 5 kDa PEG (1:0.1:0.9:1 and 1:0.1:0.9:2 weight ratio); and (2) tristearin, dioctyl sulfosuccinate and phosphatidylcholine (1:1:0.5 weight ratio). Optimized process conditions yielded dry nonagglomerated powders with high product recovery (70%, w/w). Dynamic light scattering and transmission electron microscopy showed that two size fractions of particles, with 80-120 and 200-400 nm diameters, were produced. In all final products, dimethylsulfoxide used to prepare the insulin/lipid mixture was below 20 ppm. Protein encapsulation efficiency increased up to 80% as the DMSO content in the insulin/lipid mixture increased. Compared to the particles without PEG, the polymer-containing particles dispersed rapidly in water, and the dispersions were more stable under centrifugation as less than 20% of suspended particles precipitated after extensive centrifugation. In vitro, the protein was slowly released from the formulation without PEG, while a burst and faster release were obtained from the formulations containing PEG. Subcutaneous injection to diabetic mice of insulin extracted from the particles showed that the supercritical process did not impair the protein hypoglycemic activity.

Fatigue crack closure in submicron-thick freestanding copper films

International Nuclear Information System (INIS)

Kondo, Toshiyuki; Ishii, Takaki; Hirakata, Hiroyuki; Minoshima, Kohji

2015-01-01

The fatigue crack closure in approximately 500-nm-thick freestanding copper films were investigated by in situ field emission scanning electron microscope (FESEM) observations of the fatigue crack opening/closing behavior at three stress ratios of R=0.1, 0.5, and 0.8 in the low–K max (maximum stress intensity factor) region of K max <4.5 MPam 1/2 . The direct observation of fatigue cracks clarified that crack closure occurred at R=0.1 and 0.5, while the fatigue crack was always open at R=0.8. Changes in the gage distance across the fatigue crack during a fatigue cycle were measured from the FESEM images, and the crack opening stress intensity factor K op was evaluated on the basis of the stress intensity factor K vs. the gage distance relationship. The effective stress intensity factor range ΔK eff =K max −K op was then evaluated. The R-dependence of the da/dN vs. ΔK eff relationship was smaller than that of the da/dN vs. ΔK relationship. This suggests that ΔK eff is a dominating parameter rather than ΔK in the fatigue crack propagation in the films. This paper is the first report on the presence of the fatigue crack closure in submicron-thick freestanding metallic films

Submicron hard X-ray fluorescence imaging of synthetic elements.

Science.gov (United States)

Jensen, Mark P; Aryal, Baikuntha P; Gorman-Lewis, Drew; Paunesku, Tatjana; Lai, Barry; Vogt, Stefan; Woloschak, Gayle E

2012-04-13

Synchrotron-based X-ray fluorescence microscopy (XFM) using hard X-rays focused into sub-micron spots is a powerful technique for elemental quantification and mapping, as well as microspectroscopic measurements such as μ-XANES (X-ray absorption near edge structure). We have used XFM to image and simultaneously quantify the transuranic element plutonium at the L(3) or L(2)-edge as well as Th and lighter biologically essential elements in individual rat pheochromocytoma (PC12) cells after exposure to the long-lived plutonium isotope (242)Pu. Elemental maps demonstrate that plutonium localizes principally in the cytoplasm of the cells and avoids the cell nucleus, which is marked by the highest concentrations of phosphorus and zinc, under the conditions of our experiments. The minimum detection limit under typical acquisition conditions with an incident X-ray energy of 18 keV for an average 202 μm(2) cell is 1.4 fg Pu or 2.9×10(-20) moles Pu μm(-2), which is similar to the detection limit of K-edge XFM of transition metals at 10 keV. Copper electron microscopy grids were used to avoid interference from gold X-ray emissions, but traces of strontium present in naturally occurring calcium can still interfere with plutonium detection using its L(α) X-ray emission. Copyright © 2012 Elsevier B.V. All rights reserved.

Evaluation of B3LYP, X3LYP, and M06-Class Density Functionals for Predicting the Binding Energies of Neutral, Protonated, and Deprotonated Water Clusters.

Science.gov (United States)

Bryantsev, Vyacheslav S; Diallo, Mamadou S; van Duin, Adri C T; Goddard, William A

2009-04-14

In this paper we assess the accuracy of the B3LYP, X3LYP, and newly developed M06-L, M06-2X, and M06 functionals to predict the binding energies of neutral and charged water clusters including (H2O)n, n = 2-8, 20), H3O(+)(H2O)n, n = 1-6, and OH(-)(H2O)n, n = 1-6. We also compare the predicted energies of two ion hydration and neutralization reactions on the basis of the calculated binding energies. In all cases, we use as benchmarks calculated binding energies of water clusters extrapolated to the complete basis set limit of the second-order Møller-Plesset perturbation theory with the effects of higher order correlation estimated at the coupled-cluster theory with single, double, and perturbative triple excitations in the aug-cc-pVDZ basis set. We rank the accuracy of the functionals on the basis of the mean unsigned error (MUE) between calculated benchmark and density functional theory energies. The corresponding MUE (kcal/mol) for each functional is listed in parentheses. We find that M06-L (0.73) and M06 (0.84) give the most accurate binding energies using very extended basis sets such as aug-cc-pV5Z. For more affordable basis sets, the best methods for predicting the binding energies of water clusters are M06-L/aug-cc-pVTZ (1.24), B3LYP/6-311++G(2d,2p) (1.29), and M06/aug-cc-PVTZ (1.33). M06-L/aug-cc-pVTZ also gives more accurate energies for the neutralization reactions (1.38), whereas B3LYP/6-311++G(2d,2p) gives more accurate energies for the ion hydration reactions (1.69).

Size-selected methyl lactate clusters: fragmentation and spectroscopic fingerprints of chiral recognition

Czech Academy of Sciences Publication Activity Database

Fárník, Michal; Weimann, M.; Steinbach, Ch.; Buck, U.; Borho, N.; Adler, T. B.; Suhm, M. A.

2006-01-01

Roč. 8, č. 10 (2006), s. 1148-1158 ISSN 1463-9076 Grant - others:Deutsche Forschungsgemeinschaft(DE) SFB 357; Deutsche Forschungsgemeinschaft(DE) GRK 782 Institutional research plan: CEZ:AV0Z40400503 Keywords : electron-bombardment fragmentation * methanol clusters * methanol clusters * water clusters Subject RIV: CF - Physical ; Theoretical Chemistry Impact factor: 2.892, year: 2006

Assessment of Heavy Metal Pollution in Macrophytes, Water and Sediment of a Tropical Wetland System Using Hierarchical Cluster Analysis Technique

OpenAIRE

, N. Kumar J.I.; , M. Das; , R. Mukherji; , R.N. Kumar

2011-01-01

Heavy metal pollution in aquatic ecosystems is becoming a global phenomenon because these metals are indestructible and most of them have toxic effects on living organisms. Most of the fresh water bodies all over the world are getting contaminated thus declining their suitability. Therefore, monitoring and assessment of such freshwater systems has become an environmental concern. This study aims to elucidate the useful role of the cluster analysis to assess the relationship and interdependenc...

Investigation of conspicuous infrared star cluster and star-forming region RCW 38 IR Cluster

International Nuclear Information System (INIS)

Gyulbudaghian, A.L.; May, J.

2008-01-01

An infrared star cluster RCW 38 IR Cluster, which is also a massive star-forming region, is investigated. The results of observations with SEST (Cerro is Silla, Chile) telescope on 2.6-mm 12 CO spectral line and with SIMBA on 1.2-mm continuum are given. The 12 CO observations revealed the existence of several molecular clouds, two of which (clouds I and 2) are connected with the object RCW 38 IR Cluster. Cloud 1 is a massive cloud, which has a depression in which the investigated object is embedded. It is not excluded that the depression was formed by the wind and/or emission from the young bright stars belonging to the star cluster. Rotation of cloud 2, around the axis having SE-NW direction, with an angular velocity ω 4.6 · 10 -14 s -1 is also found. A red-shifted outflow with velocity ∼+5.6 km/s, in the SE direction and perpendicular to the elongation of cloud 2 has been also found. The investigated cluster is associated with an IR point source IRAS 08573-4718, which has IR colours typical for a, non-evolved embedded (in the cloud) stellar object. The cluster is also connected with a water maser. The SIMBA image shoves the existence of a central bright condensation, coinciding with the cluster itself, and two extensions. One of these extensions (the one with SW-NE direction) coincides, both in place and shape, with cloud 2, so that it is not excluded the possibility that this extension might be also rotating like cloud 2. In the vicinity of these extensions there are condensations resembling HH objects

Vectors and submicron precision: redundancy and 3D stacking in silicon pixel detectors

CERN Document Server

Heijne, E H M; Wong, W; Idarraga, J; Visser, J; Jakubek, J; Leroy, C; Turecek, D; Visschers, J; Pospisil, S; Ballabriga, R; Vykydal, Z; Vermeulen, J; Plackett, R; Heijne, E H M; Llopart, X; Boltje, D; Campbell, M

2010-01-01

Measurements are shown of GeV pions and muons in two 300 mu m thick, Si Medipix pixel detector assemblies that are stacked on top of each other, with a 25 mu m thick brass foil in between. In such a radiation imaging semiconductor matrix with a large number of pixels along the particle trail, one can determine local space vectors for the particle trajectory instead of points. This improves pattern recognition and track reconstruction, especially in a crowded environment. Stacking of sensor planes is essential for resolving directional ambiguities. Signal charge sharing can be employed for measuring positions with submicron precision. In the measurements one notices accompanying `delta' electrons that emerge outside the particle trail, far beyond the boundaries of the 55 mu m pixel cells. The frequency of such corrupted position measurements is similar to one per 2.5mm of traversed Si.

Effect of surface Fe2O3 clusters on the photocatalytic activity of TiO2 for phenol degradation in water

International Nuclear Information System (INIS)

Sun, Qiong; Leng, Wenhua; Li, Zhen; Xu, Yiming

2012-01-01

Graphical abstract: Surface modified TiO 2 with iron oxide clusters through adsorption and decomposition of a large Fe(III) complex shows an enhanced activity for phenol degradation in water under UV light. But it was only observed with the clusters in a small size and at very low coverage on anatase. Highlights: ► Iron oxide clusters are made by decomposition of a large Fe(III) complex on TiO 2 . ► The modified anatase shows an enhanced activity for phenol photodegradation. ► The composite catalyst is very stable during four repeated experiments. - Abstract: Surface modification of TiO 2 with Fe 2 O 3 clusters was made through chemisorption of ferric phthalocyaninetetracarboxylate onto TiO 2 , followed by sintering in air to remove organic moiety. Solid characterization with electron paramagnetic resonance spectroscopy and other techniques showed that ferric oxides were highly dispersed on TiO 2 as a noncrystallized cluster, while TiO 2 phases remained unchanged. For phenol degradation in aerated aqueous suspension, only the sample containing less than 0.3 at.% Fe was more active than bare TiO 2 under UV light, whereas no activity was found under visible light. As anatase thermally transferred into rutile, the Fe-containing catalyst became less active than bare TiO 2 , mainly ascribed to the increased size of Fe 2 O 3 clusters. In the presence of H 2 O 2 , all Fe-containing catalysts were more active than bare TiO 2 . Moreover, similar trend in activity among different catalysts was also observed with the formation of hydroxyl radicals, and with the generation of photocurrent measured under N 2 with Fe/TiO 2 electrode. Present work clearly shows that only Fe 2 O 3 clusters in a small size and at low coverage on TiO 2 are beneficial to the photocatalytic reaction, while excess iron oxide is detrimental. Possible mechanism is discussed in the text.

From antinode clusters to node clusters: the concentration-dependent transition of floaters on a standing Faraday wave.

Science.gov (United States)

Sanlı, Ceyda; Lohse, Detlef; van der Meer, Devaraj

2014-05-01

A hydrophilic floating sphere that is denser than water drifts to an amplitude maximum (antinode) of a surface standing wave. A few identical floaters therefore organize into antinode clusters. However, beyond a transitional value of the floater concentration ϕ, we observe that the same spheres spontaneously accumulate at the nodal lines, completely inverting the self-organized particle pattern on the wave. From a potential energy estimate we show (i) that at low ϕ antinode clusters are energetically favorable over nodal ones and (ii) how this situation reverses at high ϕ, in agreement with the experiment.

A dual cryogenic ion trap spectrometer for the formation and characterization of solvated ionic clusters

Energy Technology Data Exchange (ETDEWEB)

Marsh, Brett M.; Voss, Jonathan M.; Garand, Etienne, E-mail: egarand@chem.wisc.edu [Department of Chemistry, University of Wisconsin-Madison, 1101 University Avenue, Madison, Wisconsin 53706 (United States)

2015-11-28

A new experimental approach is presented in which two separate cryogenic ion traps are used to reproducibly form weakly bound solvent clusters around electrosprayed ions and messenger-tag them for single-photon infrared photodissociation spectroscopy. This approach thus enables the vibrational characterization of ionic clusters comprised of a solvent network around large and non-volatile ions. We demonstrate the capabilities of the instrument by clustering water, methanol, and acetone around a protonated glycylglycine peptide. For water, cluster sizes with greater than twenty solvent molecules around a single ion are readily formed. We further demonstrate that similar water clusters can be formed around ions having a shielded charge center or those that do not readily form hydrogen bonds. Finally, infrared photodissociation spectra of D{sub 2}-tagged GlyGlyH{sup +} ⋅ (H{sub 2}O){sub 1−4} are presented. They display well-resolved spectral features and comparisons with calculations reveal detailed information on the solvation structures of this prototypical peptide.

A facility for using cluster research to study environmental problems. Workshop proceedings

Energy Technology Data Exchange (ETDEWEB)

1991-11-01

This report begins by describing the general application of cluster based research to environmental chemistry and the development of a Cluster Structure and Dynamics Research Facility (CSDRF). Next, four important areas of cluster research are described in more detail, including how they can impact environmental problems. These are: surface-supported clusters, water and contaminant interactions, time-resolved dynamic studies in clusters, and cluster structures and reactions. These facilities and equipment required for each area of research are then presented. The appendices contain workshop agenda and a listing of the researchers who participated in the workshop discussions that led to this report.

Insights into Submicron Aerosol Composition and Sources from the WINTER Aircraft Campaign Over the Eastern US.

Science.gov (United States)

Schroder, J. C.; Campuzano Jost, P.; Day, D. A.; Fibiger, D. L.; McDuffie, E. E.; Blake, N. J.; Hills, A. J.; Hornbrook, R. S.; Apel, E. C.; Weinheimer, A. J.; Campos, T. L.; Brown, S. S.; Jimenez, J. L.

2015-12-01

The WINTER aircraft campaign was a recent field experiment to probe the sources and evolution of gas pollutants and aerosols in Northeast US urban and industrial plumes during the winter. A highly customized Aerodyne aerosol mass spectrometer (AMS) was flown on the NCAR C-130 to characterize submicron aerosol composition and evolution. Thirteen research flights were conducted covering a wide range of conditions, including rural, urban, and marine environments during day and night. Organic aerosol (OA) was a large component of the submicron aerosol in the boundary layer. The fraction of OA (fOA) was smaller (35-40%) than in recent US summer campaigns (~60-70%). Biomass burning was observed to be an important source of OA in the boundary layer, which is consistent with recent wintertime studies that show a substantial contribution of residential wood burning to the OA loadings. OA oxygenation (O/C ratio) shows a broad distribution with a substantial fraction of smaller O/C ratios when compared to previous summertime campaigns. Since measurements were rarely made very close to primary sources (i.e. directly above urban areas), this is consistent with oxidative chemistry being slower during winter. SOA formation and aging in the NYC plume was observed during several flights and compared with summertime results from LA (CalNex) and Mexico City (MILAGRO). Additionally, an oxidation flow reactor (OFR) capable of oxidizing ambient air up to several equivalent days of oxidation was deployed for the first time in an aircraft platform. The aerosol outflow of the OFR was sampled with the AMS to provide real-time snapshots of the potential for aerosol formation and aging. For example, a case study of a flight through the Ohio River valley showed evidence of oxidation of SO2 to sulfate. The measured sulfate enhancements were in good agreement with our OFR chemical model. OFR results for SOA will be discussed.

Sub-micron Hard X-ray Fluorescence Imaging of Synthetic Elements

Science.gov (United States)

Jensen, Mark P.; Aryal, Baikuntha P.; Gorman-Lewis, Drew; Paunesku, Tatjana; Lai, Barry; Vogt, Stefan; Woloschak, Gayle E.

2013-01-01

Synchrotron-based X-ray fluorescence microscopy (SXFM) using hard X-rays focused into sub-micron spots is a powerful technique for elemental quantification and mapping, as well as microspectroscopic measurement such as μ-XANES (X-ray absorption near edge structure). We have used SXFM to image and simultaneously quantify the transuranic element plutonium at the L3 or L2 edge as well as lighter biologically essential elements in individual rat pheochromocytoma (PC12) cells after exposure to the long-lived plutonium isotope 242Pu. Elemental maps reveal that plutonium localizes principally in the cytoplasm of the cells and avoids the cell nucleus, which is marked by the highest concentrations of phosphorus and zinc, under the conditions of our experiments. The minimum detection limit under typical acquisition conditions for an average 202 μm2 cell is 1.4 fg Pu/cell or 2.9 × 10−20 moles Pu/μm2, which is similar to the detection limit of K-edge SXFM of transition metals at 10 keV. Copper electron microscopy grids were used to avoid interference from gold X-ray emissions, but traces of strontium present in naturally occurring calcium can still interfere with plutonium detection using its Lα X-ray emission. PMID:22444530

Theoretical studies on photoelectron and IR spectral properties of Br2.-(H2O)n clusters.

Science.gov (United States)

Pathak, A K; Mukherjee, T; Maity, D K

2007-07-28

We report vertical detachment energy (VDE) and IR spectra of Br2.-.(H2O)n clusters (n=1-8) based on first principles electronic structure calculations. Cluster structures and IR spectra are calculated at Becke's half-and-half hybrid exchange-correlation functional (BHHLYP) with a triple split valence basis function, 6-311++G(d,p). VDE for the hydrated clusters is calculated based on second order Moller-Plesset perturbation (MP2) theory with the same set of basis function. On full geometry optimization, it is observed that conformers having interwater hydrogen bonding among solvent water molecules are more stable than the structures having double or single hydrogen bonded structures between the anionic solute, Br2.-, and solvent water molecules. Moreover, a conformer having cyclic interwater hydrogen bonded network is predicted to be more stable for each size hydrated cluster. It is also noticed that up to four solvent H2O units can reside around the solute in a cyclic interwater hydrogen bonded network. The excess electron in these hydrated clusters is localized over the solute atoms. Weighted average VDE is calculated for each size (n) cluster based on statistical population of the conformers at 150 K. A linear relationship is obtained for VDE versus (n+3)(-1/3) and bulk VDE of Br2.- aqueous solution is calculated as 10.01 eV at MP2 level of theory. BHHLYP density functional is seen to make a systematic overestimation in VDE values by approximately 0.5 eV compared to MP2 data in all the hydrated clusters. It is observed that hydration increases VDE of bromine dimer anion system by approximately 6.4 eV. Calculated IR spectra show that the formation of Br2.--water clusters induces large shifts from the normal O-H stretching bands of isolated water keeping bending modes rather insensitive. Hydrated clusters, Br2.-.(H2O)n, show characteristic sharp features of O-H stretching bands of water in the small size clusters.

Theoretical studies on photoelectron and IR spectral properties of Br2.-(H2O)n clusters

Science.gov (United States)

Pathak, A. K.; Mukherjee, T.; Maity, D. K.

2007-07-01

We report vertical detachment energy (VDE) and IR spectra of Br2•-•(H2O)n clusters (n=1-8) based on first principles electronic structure calculations. Cluster structures and IR spectra are calculated at Becke's half-and-half hybrid exchange-correlation functional (BHHLYP) with a triple split valence basis function, 6-311++G(d,p). VDE for the hydrated clusters is calculated based on second order Moller-Plesset perturbation (MP2) theory with the same set of basis function. On full geometry optimization, it is observed that conformers having interwater hydrogen bonding among solvent water molecules are more stable than the structures having double or single hydrogen bonded structures between the anionic solute, Br2•-, and solvent water molecules. Moreover, a conformer having cyclic interwater hydrogen bonded network is predicted to be more stable for each size hydrated cluster. It is also noticed that up to four solvent H2O units can reside around the solute in a cyclic interwater hydrogen bonded network. The excess electron in these hydrated clusters is localized over the solute atoms. Weighted average VDE is calculated for each size (n) cluster based on statistical population of the conformers at 150K. A linear relationship is obtained for VDE versus (n+3)-1/3 and bulk VDE of Br2•- aqueous solution is calculated as 10.01eV at MP2 level of theory. BHHLYP density functional is seen to make a systematic overestimation in VDE values by ˜0.5eV compared to MP2 data in all the hydrated clusters. It is observed that hydration increases VDE of bromine dimer anion system by ˜6.4eV. Calculated IR spectra show that the formation of Br2•--water clusters induces large shifts from the normal O-H stretching bands of isolated water keeping bending modes rather insensitive. Hydrated clusters, Br2•-•(H2O)n, show characteristic sharp features of O-H stretching bands of water in the small size clusters.

On the applicability of one- and many-electron quantum chemistry models for hydrated electron clusters

Science.gov (United States)

Turi, László

2016-04-01

We evaluate the applicability of a hierarchy of quantum models in characterizing the binding energy of excess electrons to water clusters. In particular, we calculate the vertical detachment energy of an excess electron from water cluster anions with methods that include one-electron pseudopotential calculations, density functional theory (DFT) based calculations, and ab initio quantum chemistry using MP2 and eom-EA-CCSD levels of theory. The examined clusters range from the smallest cluster size (n = 2) up to nearly nanosize clusters with n = 1000 molecules. The examined cluster configurations are extracted from mixed quantum-classical molecular dynamics trajectories of cluster anions with n = 1000 water molecules using two different one-electron pseudopotenial models. We find that while MP2 calculations with large diffuse basis set provide a reasonable description for the hydrated electron system, DFT methods should be used with precaution and only after careful benchmarking. Strictly tested one-electron psudopotentials can still be considered as reasonable alternatives to DFT methods, especially in large systems. The results of quantum chemistry calculations performed on configurations, that represent possible excess electron binding motifs in the clusters, appear to be consistent with the results using a cavity structure preferring one-electron pseudopotential for the hydrated electron, while they are in sharp disagreement with the structural predictions of a non-cavity model.

On the applicability of one- and many-electron quantum chemistry models for hydrated electron clusters

Energy Technology Data Exchange (ETDEWEB)

Turi, László, E-mail: turi@chem.elte.hu [Department of Physical Chemistry, Eötvös Loránd University, P.O. Box 32, H-1518 Budapest 112 (Hungary)

2016-04-21

We evaluate the applicability of a hierarchy of quantum models in characterizing the binding energy of excess electrons to water clusters. In particular, we calculate the vertical detachment energy of an excess electron from water cluster anions with methods that include one-electron pseudopotential calculations, density functional theory (DFT) based calculations, and ab initio quantum chemistry using MP2 and eom-EA-CCSD levels of theory. The examined clusters range from the smallest cluster size (n = 2) up to nearly nanosize clusters with n = 1000 molecules. The examined cluster configurations are extracted from mixed quantum-classical molecular dynamics trajectories of cluster anions with n = 1000 water molecules using two different one-electron pseudopotenial models. We find that while MP2 calculations with large diffuse basis set provide a reasonable description for the hydrated electron system, DFT methods should be used with precaution and only after careful benchmarking. Strictly tested one-electron psudopotentials can still be considered as reasonable alternatives to DFT methods, especially in large systems. The results of quantum chemistry calculations performed on configurations, that represent possible excess electron binding motifs in the clusters, appear to be consistent with the results using a cavity structure preferring one-electron pseudopotential for the hydrated electron, while they are in sharp disagreement with the structural predictions of a non-cavity model.

Brightest Cluster Galaxies in REXCESS Clusters

Science.gov (United States)

Haarsma, Deborah B.; Leisman, L.; Bruch, S.; Donahue, M.

2009-01-01

Most galaxy clusters contain a Brightest Cluster Galaxy (BCG) which is larger than the other cluster ellipticals and has a more extended profile. In the hierarchical model, the BCG forms through many galaxy mergers in the crowded center of the cluster, and thus its properties give insight into the assembly of the cluster as a whole. In this project, we are working with the Representative XMM-Newton Cluster Structure Survey (REXCESS) team (Boehringer et al 2007) to study BCGs in 33 X-ray luminous galaxy clusters, 0.055 < z < 0.183. We are imaging the BCGs in R band at the Southern Observatory for Astrophysical Research (SOAR) in Chile. In this poster, we discuss our methods and give preliminary measurements of the BCG magnitudes, morphology, and stellar mass. We compare these BCG properties with the properties of their host clusters, particularly of the X-ray emitting gas.

Nanostructured submicron block copolymer dots by sacrificial stamping: a potential preconcentration platform for locally resolved sensing, chemistry and cellular interactions

OpenAIRE

Hou, Peilong; Han, Weijia; Philippi, Michael; Schäfer, Helmut; Steinhart, Martin

2018-01-01

Classical contact lithography involves patterning of surfaces by embossing or by transfer of ink. We report direct lithographic transfer of parts of sacrificial stamps onto counterpart surfaces. Using sacrificial stamps consisting of the block copolymer polystyrene-block-poly(2-pyridine) (PS-b-P2VP), we deposited arrays of nanostructured submicron PS-b-P2VP dots with heights of about 100 nm onto silicon wafers and glass slides. The sacrificial PS-b-P2VP stamps were topographically patterned w...

Ionic composition of submicron particles (PM1.0) during the long-lasting haze period in January 2013 in Wuhan, central China.

Science.gov (United States)

Cheng, Hairong; Gong, Wei; Wang, Zuwu; Zhang, Fan; Wang, Xinming; Lv, Xiaopu; Liu, Jia; Fu, Xiaoxin; Zhang, Gan

2014-04-01

In January 2013, a long-lasting severe haze episode occurred in Northern and Central China; at its maximum, it covered a land area of approximately 1.4 million km(2). In Wuhan, the largest city in Central China, this event was the most severe haze episode in the 21st century. Aerosol samples of submicron particles (PM1.0) were collected during the long-lasting haze episode at an urban site and a suburban site in Wuhan to investigate the ion characteristics of PM1.0 in this area. The mass concentrations of PM1.0 and its water-soluble inorganic ions (WSIIs) were almost at the same levels at two sites, which indicates that PM1.0 pollution occurs on a regional scale in Wuhan. WSIIs (Na(+), NH4(+), K(+), Mg(2+), Ca(2+), Cl(-), NO3(-) and SO4(2-)) were the dominant chemical species and constituted up to 48.4% and 47.4% of PM1.0 at WD and TH, respectively. The concentrations of PM1.0 and WSIIs on haze days were approximately two times higher than on normal days. The ion balance calculations indicate that the particles were more acidic on haze days than on normal days. The results of the back trajectory analysis imply that the high concentrations of PM1.0 and its water-soluble inorganic ions may be caused by stagnant weather conditions in Wuhan. Copyright © 2014 The Research Centre for Eco-Environmental Sciences, Chinese Academy of Sciences. Published by Elsevier B.V. All rights reserved.

Spatially Resolved Distribution of Fe Species around Microbes at the Submicron Scale in Natural Bacteriogenic Iron Oxides.

Science.gov (United States)

Suga, Hiroki; Kikuchi, Sakiko; Takeichi, Yasuo; Miyamoto, Chihiro; Miyahara, Masaaki; Mitsunobu, Satoshi; Ohigashi, Takuji; Mase, Kazuhiko; Ono, Kanta; Takahashi, Yoshio

2017-09-27

Natural bacteriogenic iron oxides (BIOS) were investigated using local-analyzable synchrotron-based scanning transmission X-ray microscopy (STXM) with a submicron-scale resolution. Cell, cell sheath interface (EPS), and sheath in the BIOS were clearly depicted using C-, N-, and O- near edge X-ray absorption fine structure (NEXAFS) obtained through STXM measurements. Fe-NEXAFS obtained from different regions of BIOS indicated that the most dominant iron mineral species was ferrihydrite. Fe(II)- and/or Fe(III)-acidic polysaccharides accompanied ferrihydrite near the cell and EPS regions. Our STXM/NEXAFS analysis showed that Fe species change continuously between the cell, EPS, and sheath under several 10-nm scales.

Study of the stabilization energies of halide-water clusters: An application of first-principles interaction potentials based on a polarizable and flexible model

International Nuclear Information System (INIS)

Ayala, Regla; Martinez, Jose M.; Pappalardo, Rafael R.; Sanchez Marcos, Enrique

2004-01-01

The aim of this work is to compute the stabilization energy E stab (n) of [X(H 2 O) n ] - (X≡F, Br, and I for n=1-60) clusters from Monte Carlo simulations using first-principles ab initio potentials. Stabilization energy of [X(H 2 O) n ] - clusters is defined as the difference between the vertical photodeachment energy of the cluster and the electron affinity of the isolated halide. On one hand, a study about the relation between cluster structure and the E stab (n) value, as well as the dependence of the latter with temperature is performed, on the other hand, a test on the reliability of our recently developed first-principles halide ion-water interaction potentials is carried out. Two different approximations were applied: (1) the Koopmans' theorem and (2) calculation of the difference between the interaction energy of [X(H 2 O) n ] - and [X(H 2 O) n ] clusters using the same ab initio interaction potentials. The developed methodology allows for using the same interaction potentials in the case of the ionic and neutral clusters with the proviso that the charge of the halide anion was switched off in the latter. That is, no specific parametrization of the interaction potentials to fit the magnitude under study was done. The good agreement between our predicted E stab (n) and experimental data allows us to validate the first-principles interaction potentials developed elsewhere and used in this study, and supports the fact that this magnitude is mainly determined by electrostatic factors, which can be described by our interaction potentials. No relation between the value of E stab (n) and the structure of clusters has been found. The diversity of E stab (n) values found for different clusters with similar interaction energy indicates the need for statistical information to properly estimate the stabilization energy of the halide anions. The effect of temperature in the prediction of the E stab (n) is not significant as long as it was high enough to avoid

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.

Composition dependent selectivity in the coadsorption of H2O and CO on pure and binary silver-gold clusters

Science.gov (United States)

Fleischer, Irene; Popolan, Denisia M.; Krstić, Marjan; Bonačić-Koutecký, Vlasta; Bernhardt, Thorsten M.

2013-04-01

Small cationic gold clusters exhibit a strong affinity toward carbon monoxide. This prevents the coadsorption of water which would be the first step of a catalytic water gas shift chemistry on these clusters. In a gas phase ion trap experiment with mass selected AgnAum+ it was however possible to demonstrate that the replacement of gold by silver atoms in triatomic cluster ions liberates sites for H2O adsorption. The resulting observed coadsorption effect occurs at a cross-over in the molecular binding energies of carbon monoxide and water to these clusters determined by reaction kinetics measurements and first principles calculations.

Binding motif of terminal alkynes on gold clusters.

Science.gov (United States)

Maity, Prasenjit; Takano, Shinjiro; Yamazoe, Seiji; Wakabayashi, Tomonari; Tsukuda, Tatsuya

2013-06-26

Gold clusters protected by terminal alkynes (1-octyne (OC-H), phenylacetylene (PA-H) and 9-ethynyl-phenanthrene (EPT-H)) were prepared by the ligand exchange of small (diameter alkynes on Au clusters was investigated using various spectroscopic methods. FTIR and Raman spectroscopy revealed that terminal hydrogen is lost during the ligand exchange and that the C≡C bond of the alkynyl group is weakened upon attachment to the Au clusters. Acidification of the water phase after the ligand exchange indicated that the ligation of alkynyl groups to the Au clusters proceeds via deprotonation of the alkynes. A series of precisely defined Au clusters, Au34(PA)16, Au54(PA)26, Au30(EPT)13, Au35(EPT)18, and Au(41-43)(EPT)(21-23), were synthesized and characterized in detail to obtain further insight into the interfacial structures. Careful mass analysis confirmed the ligation of the alkynes in the dehydrogenated form. An upright configuration of the alkynes on Au clusters was suggested from the Au to alkyne ratios and photoluminescence from the excimer of the EPT ligands. EXAFS analysis implied that the alkynyl carbon is bound to bridged or hollow sites on the cluster surface.

Dynamics and Fragmentation of Hydrogen Bonded and van der Waal Clusters upon 26.5 eV Soft X-ray Laser Ionization

Science.gov (United States)

Dong, Feng; Heinbuch, Scott; Bernstein, Elliot; Rocca, Jorge

2006-05-01

A desk-top soft x-ray laser is applied to the study of water, methanol, ammonia, sulfur dioxide, carbon dioxide, mixed sulfur dioxide-water, and mixed carbon dioxide-water clusters through single photon ionization time of flight mass spectroscopy. Almost all of the energy above the vertical ionization energy is removed by the ejected electron. Protonated water, methanol, and ammonia clusters dominate the mass spectra for the first three systems. The temperatures of the neutral water and methanol clusters can be estimated. In the case of pure SO2 and CO2, the mass spectra are dominated by (SO2)n^+ and (CO2)n^+ cluster series. When a high or low concentration of SO2/CO2 is mixed with water, we observe (SO2/CO2)nH2O^+ or SO2/CO2(H2O)nH^+ in the mass spectra, respectively. The unimolecular dissociation rate constants for reactions involving loss of one neutral molecule are calculated for the protonated water, methanol, and ammonia clusters as well as for SO2 and CO2 clusters. We find that the 26.5 eV soft x-ray laser is a nearly ideal tool for the study of hydrogen bonded and van der Waals cluster systems and we are currently exploring its usefulness for other more strongly bound systems.

Metal cluster compounds - chemistry and importance; clusters containing isolated main group element atoms, large metal cluster compounds, cluster fluxionality

International Nuclear Information System (INIS)

Walther, B.

1988-01-01

This part of the review on metal cluster compounds deals with clusters containing isolated main group element atoms, with high nuclearity clusters and metal cluster fluxionality. It will be obvious that main group element atoms strongly influence the geometry, stability and reactivity of the clusters. High nuclearity clusters are of interest in there own due to the diversity of the structures adopted, but their intermediate position between molecules and the metallic state makes them a fascinating research object too. These both sites of the metal cluster chemistry as well as the frequently observed ligand and core fluxionality are related to the cluster metal and surface analogy. (author)

Clay-Alcohol-Water Dispersions: Anomalous Viscosity Changes Due to Network Formation of Clay Nanosheets Induced by Alcohol Clustering.

Science.gov (United States)

Kimura, Yuji; Haraguchi, Kazutoshi

2017-05-16

Clay-alcohol-water ternary dispersions were compared with alcohol-water binary mixtures in terms of viscosity and optical absorbance. Aqueous clay dispersions to which lower alcohols (ethanol, 1-propanol, 2-propanol, and tert-butanol) were added exhibited significant viscosity anomalies (maxima) when the alcohol content was 30-55 wt %, as well as optical absorbance anomalies (maxima). The maximum viscosity (η max ) depended strongly on the clay content and varied between 300 and 8000 mPa·s, making it remarkably high compared with the viscosity anomalies (2 mPa·s) observed in alcohol-water binary mixtures. The alcohol content at η max decreased as the hydrophobicity of the alcohol increased. The ternary dispersions with viscosity anomalies exhibited thixotropic behaviors. The effects of other hydrophilic solvents (glycols) and other kinds of clays were also clarified. Based on these findings and the average particle size changes, the viscosity anomalies in the ternary dispersions were explained by alcohol-clustering-induced network formation of the clay nanosheets. It was estimated that 0.9, 1.7, and 2.5 H 2 O molecules per alcohol molecule were required to stabilize the ethanol, 2-propanol, and tert-butanol, respectively, in the clay-alcohol-water dispersions.

Dynamics of Surfactant Clustering at Interfaces and Its Influence on the Interfacial Tension: Atomistic Simulation of a Sodium Hexadecane-Benzene Sulfonate-Tetradecane-Water System.

Science.gov (United States)

Paredes, Ricardo; Fariñas-Sánchez, Ana Isabel; Medina-Rodrı Guez, Bryan; Samaniego, Samantha; Aray, Yosslen; Álvarez, Luis Javier

2018-03-06

The process of equilibration of the tetradecane-water interface in the presence of sodium hexadecane-benzene sulfonate is studied using intensive atomistic molecular dynamics simulations. Starting as an initial point with all of the surfactants at the interface, it is obtained that the equilibration time of the interface (several microseconds) is orders of magnitude higher than previously reported simulated times. There is strong evidence that this slow equilibration process is due to the aggregation of surfactants molecules on the interface. To determine this fact, temporal evolution of interfacial tension and interfacial formation energy are studied and their temporal variations are correlated with cluster formation. To study cluster evolution, the mean cluster size and the probability that a molecule of surfactant chosen at random is free are obtained as a function of time. Cluster size distribution is estimated, and it is observed that some of the molecules remain free, whereas the rest agglomerate. Additionally, the temporal evolution of the interfacial thickness and the structure of the surfactant molecules on the interface are studied. It is observed how this structure depends on whether the molecules agglomerate or not.

Fine particle water and pH in the Eastern Mediterranean: Sources, variability and implications for nutrients availability

Science.gov (United States)

Bougiatioti, Aikaterini; Nikolaou, Panayiota; Stavroulas, Iasonas; Kouvarakis, Giorgos; Nenes, Athanasios; Weber, Rodney; Kanakidou, Maria; Mihalopoulos, Nikolaos

2016-04-01

Atmospheric particles have the ability to absorb significant amounts of water, which greatly impacts on their physical and chemical properties. Direclty linked to aerosol pH and LWC is the bioavailability of nutrients contained within mineral dust, involving pH-dependent catalyzed redox-reaction pathways. Liquid water content (LWC) and pH, even though are important constituents of the aerosol phase, are rarely monitored. Direct measurements of aerosol pH "in situ" are scarce and require considerations owing to the non-conserved nature of the hydronium ion and partial dissociation of inorganic and organic electrolytes in the aerosol. To overcome these challenges, indirect alternatives such as measuring the semi-volatile partitioning of key species sensitive to pH, combined with comprehensive models are used to provide a reasonably accurate estimate of pH that can be carried out with routine measurements. Using concurrent measurements of aerosol chemical composition, tandem light scattering coefficients and the thermodynamic model ISORROPIA-II, LWC mass concentrations associated with the aerosol inorganic and organic components are determined for the remote background site of Finokalia, Crete. The predicted water was subsequently compared to the one measured by the ambient versus dry light scattering coefficients. The sum of Winorg and Worg was highly correlated and in close agreement with the measured LWC (on average within 10%), with slope 0.92 (R2=0.8) for the whole measurement period between August and November 2012 (n=5201 points). As expected, the highest fine aerosol water values are observed during night-time, when RH is at its maximum, resulting in important water uptake. The average concentration of total aerosol water was found to be 2.19±1.75 μg m-3, which according to the dry mass measurements, can contribute on average up to 33% to the total aerosol submicron mass. The average Worg was found to be 0.56±0.37 μg m-3, which constitutes about 28% of the

Sub-micron opto-chemical probes for studying living neurons

Science.gov (United States)

Hossein-Zadeh, M.; Delgado, J.; Schweizer, F.; Lieberman, R.

2017-02-01

We have fabricated sub-micron opto-chemical probes for pH, oxygen and calcium monitoring and demonstrated their application in intracellular and extracellular monitoring of neurons (cortical neuronal cultures and acute hippocampal slices). Using these probes, we have measured extracellular pH in the stratum radiatum of the CA1 region of mouse hippocampus upon stimulation of presynaptic Schaffer collateral axons. Synaptic transmission was monitored using standard electrophysiological techniques. We find that the local pH transiently changes in response to synaptic stimulation. In addition, the geometry of the functionalized region on the probe combined with high sensitivity imaging enables simultaneous monitoring of spatially adjacent but distinct compartments. As proof of concept we impaled cultured neurons with the probe measured calcium and pH inside as well as directly outside of neurons as we changed the pH and calcium concentration in the physiological solution in the perfusion chamber. As such these probes can be used to study the impact of the environment on both cellular and extra-cellular space. Additionally as the chemical properties of the surrounding medium can be controlled and monitored with high precision, these probes enable differential measurement of the target parameter referenced to a stable bath. This approach eliminates the uncertainties associated with non-chemical fluctuations in the fluorescent emission and result in a self-calibrated opto-chemical probe. We have also demonstrated multifunctional probes that are capable of measuring up to three parameters in the extracellular space in brain slices.

PREFACE: Nuclear Cluster Conference; Cluster'07

Science.gov (United States)

Freer, Martin

2008-05-01

The Cluster Conference is a long-running conference series dating back to the 1960's, the first being initiated by Wildermuth in Bochum, Germany, in 1969. The most recent meeting was held in Nara, Japan, in 2003, and in 2007 the 9th Cluster Conference was held in Stratford-upon-Avon, UK. As the name suggests the town of Stratford lies upon the River Avon, and shortly before the conference, due to unprecedented rainfall in the area (approximately 10 cm within half a day), lay in the River Avon! Stratford is the birthplace of the `Bard of Avon' William Shakespeare, and this formed an intriguing conference backdrop. The meeting was attended by some 90 delegates and the programme contained 65 70 oral presentations, and was opened by a historical perspective presented by Professor Brink (Oxford) and closed by Professor Horiuchi (RCNP) with an overview of the conference and future perspectives. In between, the conference covered aspects of clustering in exotic nuclei (both neutron and proton-rich), molecular structures in which valence neutrons are exchanged between cluster cores, condensates in nuclei, neutron-clusters, superheavy nuclei, clusters in nuclear astrophysical processes and exotic cluster decays such as 2p and ternary cluster decay. The field of nuclear clustering has become strongly influenced by the physics of radioactive beam facilities (reflected in the programme), and by the excitement that clustering may have an important impact on the structure of nuclei at the neutron drip-line. It was clear that since Nara the field had progressed substantially and that new themes had emerged and others had crystallized. Two particular topics resonated strongly condensates and nuclear molecules. These topics are thus likely to be central in the next cluster conference which will be held in 2011 in the Hungarian city of Debrechen. Martin Freer Participants and Cluster'07

EQUIPMENT FOR NONDESTRUCTIVE TESTING OF SILICON WAFERS SUBMICRON TOPOLOGY DURING THE FABRICATION OF INTEGRATED CIRCUITS

Directory of Open Access Journals (Sweden)

S. A. Chizhik

2013-01-01

Full Text Available The advantages of using an atomic force microscopy in manufacturing of submicron integrated circuits are described. The possibilities of characterizing the surface morphology and the etching profile for silicon substrate and bus lines, estimation of the periodicity and size of bus lines, geometrical stability for elementary bus line are shown. Methods of optical and atomic force microcopies are combined in one diagnostic unit. Scanning  probe  microscope  (SPM  200  is  designed  and  produced.  Complex  SPM  200  realizes  nondestructive control of microelectronics elements made on silicon wafers up to 200 mm in diameter and it is introduced by JSC «Integral» for the purpose of operational control, metrology and acceptance of the final product.

High-dimensional neural network potentials for solvation: The case of protonated water clusters in helium

Science.gov (United States)

Schran, Christoph; Uhl, Felix; Behler, Jörg; Marx, Dominik

2018-03-01

The design of accurate helium-solute interaction potentials for the simulation of chemically complex molecules solvated in superfluid helium has long been a cumbersome task due to the rather weak but strongly anisotropic nature of the interactions. We show that this challenge can be met by using a combination of an effective pair potential for the He-He interactions and a flexible high-dimensional neural network potential (NNP) for describing the complex interaction between helium and the solute in a pairwise additive manner. This approach yields an excellent agreement with a mean absolute deviation as small as 0.04 kJ mol-1 for the interaction energy between helium and both hydronium and Zundel cations compared with coupled cluster reference calculations with an energetically converged basis set. The construction and improvement of the potential can be performed in a highly automated way, which opens the door for applications to a variety of reactive molecules to study the effect of solvation on the solute as well as the solute-induced structuring of the solvent. Furthermore, we show that this NNP approach yields very convincing agreement with the coupled cluster reference for properties like many-body spatial and radial distribution functions. This holds for the microsolvation of the protonated water monomer and dimer by a few helium atoms up to their solvation in bulk helium as obtained from path integral simulations at about 1 K.

Toward the development of erosion-free ultrasonic cavitation cleaning with gas-supersaturated water

Science.gov (United States)

Yamashita, Tatsuya; Ando, Keita

2015-11-01

In ultrasonic cleaning, contaminant particles attached at target surfaces are removed by liquid flow or acoustic waves that are induced by acoustic cavitation bubbles. However, the inertial collapse of such bubbles often involve strong shock emission or water hammer by re-entrant jets, thereby giving rise to material erosion. Here, we aim at developing an erosion-free ultrasonic cleaning technique with the aid of gas-supersaturated water. The key idea is that (gaseous) cavitation is triggered easily even with low-intensity sonication in water where gases are dissolved beyond Henry's saturation limit, allowing us to buffer violent bubble collapse. In this presentation, we report on observations of the removal of micron/submicron-sized particles attached at glass surfaces by the action of gaseous cavitation bubbles under low-intensity sonication.

Sub-micron indent induced plastic deformation in copper and irradiated steel; Deformation plastique induite par l'essai d'indentation submicronique, dans le cuivre et l'acier 316L irradie

Energy Technology Data Exchange (ETDEWEB)

Robertson, Ch

1999-07-01

In this work we aim to study the indent induced plastic deformation. For this purpose, we have developed a new approach, whereby the indentation curves provides the mechanical behaviour, while the deformation mechanisms are observed thanks to Transmission Electron Microscopy (TEM). In order to better understand how an indent induced dislocation microstructure forms, numerical modeling of the indentation process at the scale of discrete dislocations has been worked out as well. Validation of this modeling has been performed through direct comparison of the computed microstructures with TEM micrographs of actual indents in pure Cu (001]. Irradiation induced modifications of mechanical behaviour of ion irradiated 316L have been investigated, thanks to the mentioned approach. An important hardening effect was reported from indentation data (about 50%), on helium irradiated 316L steel. TEM observations of the damage zone clearly show that this behaviour is associated with the presence of He bubbles. TEM observations of the indent induced plastic zone also showed that the extent of the plastic zone is strongly correlated with hardness, that is to say: harder materials gets a smaller plastic zone. These results thus clearly established that the selected procedure can reveal any irradiation induced hardening in sub-micron thick ion irradiated layers. The behaviour of krypton irradiated 316L steel is somewhat more puzzling. In one hand indeed, a strong correlation between the defect cluster size and densities on the irradiation temperature is observed in the 350 deg. C - 600 deg. C range, thanks to TEM observations of the damage zone. On the other hand, irradiation induced hardening reported from indentation data is relatively small (about 10%) and shows no dependence upon the irradiation temperature (within the mentioned range). In addition, it has been shown that the reported hardening vanishes following appropriate post-irradiation annealing, although most of the TEM

Formation of stable products from cluster-cluster collisions

International Nuclear Information System (INIS)

Alamanova, Denitsa; Grigoryan, Valeri G; Springborg, Michael

2007-01-01

The formation of stable products from copper cluster-cluster collisions is investigated by using classical molecular-dynamics simulations in combination with an embedded-atom potential. The dependence of the product clusters on impact energy, relative orientation of the clusters, and size of the clusters is studied. The structures and total energies of the product clusters are analysed and compared with those of the colliding clusters before impact. These results, together with the internal temperature, are used in obtaining an increased understanding of cluster fusion processes

Understanding Irrigator Bidding Behavior in Australian Water Markets in Response to Uncertainty

Directory of Open Access Journals (Sweden)

Alec Zuo

2014-11-01

Full Text Available Water markets have been used by Australian irrigators as a way to reduce risk and uncertainty in times of low water allocations and rainfall. However, little is known about how irrigators’ bidding trading behavior in water markets compares to other markets, nor is it known what role uncertainty and a lack of water in a variable and changing climate plays in influencing behavior. This paper studies irrigator behavior in Victorian water markets over a decade (a time period that included a severe drought. In particular, it studies the evidence for price clustering (when water bids/offers end mostly around particular numbers, a common phenomenon present in other established markets. We found that clustering in bid/offer prices in Victorian water allocation markets was influenced by uncertainty and strategic behavior. Water traders evaluate the costs and benefits of clustering and act according to their risk aversion levels. Water market buyer clustering behavior was mostly explained by increased market uncertainty (in particular, hotter and drier conditions, while seller-clustering behavior is mostly explained by strategic behavioral factors which evaluate the costs and benefits of clustering.

Using Cluster Analysis to Compartmentalize a Large Managed Wetland Based on Physical, Biological, and Climatic Geospatial Attributes.

Science.gov (United States)

Hahus, Ian; Migliaccio, Kati; Douglas-Mankin, Kyle; Klarenberg, Geraldine; Muñoz-Carpena, Rafael

2018-04-27

Hierarchical and partitional cluster analyses were used to compartmentalize Water Conservation Area 1, a managed wetland within the Arthur R. Marshall Loxahatchee National Wildlife Refuge in southeast Florida, USA, based on physical, biological, and climatic geospatial attributes. Single, complete, average, and Ward's linkages were tested during the hierarchical cluster analyses, with average linkage providing the best results. In general, the partitional method, partitioning around medoids, found clusters that were more evenly sized and more spatially aggregated than those resulting from the hierarchical analyses. However, hierarchical analysis appeared to be better suited to identify outlier regions that were significantly different from other areas. The clusters identified by geospatial attributes were similar to clusters developed for the interior marsh in a separate study using water quality attributes, suggesting that similar factors have influenced variations in both the set of physical, biological, and climatic attributes selected in this study and water quality parameters. However, geospatial data allowed further subdivision of several interior marsh clusters identified from the water quality data, potentially indicating zones with important differences in function. Identification of these zones can be useful to managers and modelers by informing the distribution of monitoring equipment and personnel as well as delineating regions that may respond similarly to future changes in management or climate.

Document clustering methods, document cluster label disambiguation methods, document clustering apparatuses, and articles of manufacture

Science.gov (United States)

Sanfilippo, Antonio [Richland, WA; Calapristi, Augustin J [West Richland, WA; Crow, Vernon L [Richland, WA; Hetzler, Elizabeth G [Kennewick, WA; Turner, Alan E [Kennewick, WA

2009-12-22

Document clustering methods, document cluster label disambiguation methods, document clustering apparatuses, and articles of manufacture are described. In one aspect, a document clustering method includes providing a document set comprising a plurality of documents, providing a cluster comprising a subset of the documents of the document set, using a plurality of terms of the documents, providing a cluster label indicative of subject matter content of the documents of the cluster, wherein the cluster label comprises a plurality of word senses, and selecting one of the word senses of the cluster label.

Hydration of alcohol clusters in 1-propanol-water mixture studied by quasielastic neutron scattering and an interpretation of anomalous excess partial molar volume.

Science.gov (United States)

Misawa, M; Inamura, Y; Hosaka, D; Yamamuro, O

2006-08-21

Quasielastic neutron scattering measurements have been made for 1-propanol-water mixtures in a range of alcohol concentration from 0.0 to 0.167 in mole fraction at 25 degrees C. Fraction alpha of water molecules hydrated to fractal surface of alcohol clusters in 1-propanol-water mixture was obtained as a function of alcohol concentration. Average hydration number N(ws) of 1-propanol molecule is derived from the value of alpha as a function of alcohol concentration. By extrapolating N(ws) to infinite dilution, we obtain values of 12-13 as hydration number of isolated 1-propanol molecule. A simple interpretation of structural origin of anomalous excess partial molar volume of water is proposed and as a result a simple equation for the excess partial molar volume is deduced in terms of alpha. Calculated values of the excess partial molar volumes of water and 1-propanol and the excess molar volume of the mixture are in good agreement with experimental values.

A stepped wedge, cluster-randomized trial of a household UV-disinfection and safe storage drinking water intervention in rural Baja California Sur, Mexico.

Science.gov (United States)

Gruber, Joshua S; Reygadas, Fermin; Arnold, Benjamin F; Ray, Isha; Nelson, Kara; Colford, John M

2013-08-01

In collaboration with a local non-profit organization, this study evaluated the expansion of a program that promoted and installed Mesita Azul, an ultraviolet-disinfection system designed to treat household drinking water in rural Mexico. We conducted a 15-month, cluster-randomized stepped wedge trial by randomizing the order in which 24 communities (444 households) received the intervention. We measured primary outcomes (water contamination and diarrhea) during seven household visits. The intervention increased the percentage of households with access to treated and safely stored drinking water (23-62%), and reduced the percentage of households with Escherichia coli contaminated drinking water (risk difference (RD): -19% [95% CI: -27%, -14%]). No significant reduction in diarrhea was observed (RD: -0.1% [95% CI: -1.1%, 0.9%]). We conclude that household water quality improvements measured in this study justify future promotion of the Mesita Azul, and that future studies to measure its health impact would be valuable if conducted in populations with higher diarrhea prevalence.

Chemical speciation of 239240Pu and 137Cs in Lake Michigan waters

International Nuclear Information System (INIS)

Alberts, J.J.; Wahlgren, M.A.; Jehn, P.J.; Nelson, D.M.; Orlandini, K.A.

1974-01-01

Studies of the submicron size distribution and charge characteristics of naturally occurring levels of 239 Pu, 240 Pu, and 137 Cs were conducted to help define the physico-chemical state of these fallout derived nuclides in Lake Michigan waters and in precipitation samples taken in the Argonne Laboratory area. Procedures are described for sample collection, size distribution determination, analysis of ion exchange resins, and plutonium determination by evaporation. Results indicated that the radioisotopes exist in several different fractions within the water column and that the total charge of these fractions is different from what would be predicted by simple solution chemistry. The distribution of the isotopes in snow appears to be different from that in the water column, indicating that considerable chemical or physical transformations must take place after the atomospheric input has reached the lake surface

Root uptake and phytotoxicity of nanosized molybdenum octahedral clusters

International Nuclear Information System (INIS)

Aubert, Tangi; Burel, Agnès; Esnault, Marie-Andrée; Cordier, Stéphane; Grasset, Fabien; Cabello-Hurtado, Francisco

2012-01-01

Highlights: ► We investigated the effect of nanosized Mo 6 clusters on the growth of rapeseed plants. ► The aggregation state of the clusters depends on the dispersion medium. ► The concentration-dependant toxicity of the clusters depends on aggregation state. ► We took into account the possible contribution to toxicity of dissolved ionic species. ► The root uptake of the clusters was followed by NanoSIMS. - Abstract: Here are examined the root uptake and phytotoxicity of octahedral hexamolybdenum clusters on rapeseed plants using the solid state compound Cs 2 Mo 6 Br 14 as cluster precursor. [Mo 6 Br 14 ] 2− cluster units are nanosized entities offering a strong and stable emission in the near-infrared region with numerous applications in biotechnology. To investigate cluster toxicity on rapeseed plants, two different culture systems have been set up, using either a water-sorbing suspension of cluster aggregates or an ethanol-sorbing solution of dispersed nanosized clusters. Size, shape, surface area and state of clusters in both medium were analyzed by FE-SEM, BET and XPS. The potential contribution of cluster dissolution to phytotoxicity was evaluated by ICP-OES and toxicity analysis of Mo, Br and Cs. We showed that the clusters did not affect seed germination but greatly inhibited plant growth. This inhibition was much more important when plants were treated with nanosized entities than with microsized cluster aggregates. In addition, nanosized clusters affected the root morphology in a different manner than microsized cluster aggregates, as shown by FE-SEM observations. The root penetration of the clusters was followed by secondary ion mass spectroscopy with high spatial resolution (NanoSIMS) and was also found to be much more important for treatments with nanosized clusters.

Root uptake and phytotoxicity of nanosized molybdenum octahedral clusters

Energy Technology Data Exchange (ETDEWEB)

Aubert, Tangi [Solid State Chemistry and Materials Group, UMR CNRS 6226 Sciences Chimiques de Rennes, University of Rennes 1, 263 av. du General Leclerc, Campus de Beaulieu, 35042 Rennes (France); Burel, Agnes [Electronic Microscopy Department, University of Rennes 1, 2 av. du Professeur Leon-Bernard, Campus de Villejean, 35043 Rennes (France); Esnault, Marie-Andree [Mechanisms at the Origin of Biodiversity Team, UMR CNRS 6553 Ecobio, University of Rennes 1, 263 av. du General Leclerc, Campus de Beaulieu, 35042 Rennes (France); Cordier, Stephane; Grasset, Fabien [Solid State Chemistry and Materials Group, UMR CNRS 6226 Sciences Chimiques de Rennes, University of Rennes 1, 263 av. du General Leclerc, Campus de Beaulieu, 35042 Rennes (France); Cabello-Hurtado, Francisco, E-mail: francisco.cabello@univ-rennes1.fr [Mechanisms at the Origin of Biodiversity Team, UMR CNRS 6553 Ecobio, University of Rennes 1, 263 av. du General Leclerc, Campus de Beaulieu, 35042 Rennes (France)

2012-06-15

Highlights: Black-Right-Pointing-Pointer We investigated the effect of nanosized Mo{sub 6} clusters on the growth of rapeseed plants. Black-Right-Pointing-Pointer The aggregation state of the clusters depends on the dispersion medium. Black-Right-Pointing-Pointer The concentration-dependant toxicity of the clusters depends on aggregation state. Black-Right-Pointing-Pointer We took into account the possible contribution to toxicity of dissolved ionic species. Black-Right-Pointing-Pointer The root uptake of the clusters was followed by NanoSIMS. - Abstract: Here are examined the root uptake and phytotoxicity of octahedral hexamolybdenum clusters on rapeseed plants using the solid state compound Cs{sub 2}Mo{sub 6}Br{sub 14} as cluster precursor. [Mo{sub 6}Br{sub 14}]{sup 2-} cluster units are nanosized entities offering a strong and stable emission in the near-infrared region with numerous applications in biotechnology. To investigate cluster toxicity on rapeseed plants, two different culture systems have been set up, using either a water-sorbing suspension of cluster aggregates or an ethanol-sorbing solution of dispersed nanosized clusters. Size, shape, surface area and state of clusters in both medium were analyzed by FE-SEM, BET and XPS. The potential contribution of cluster dissolution to phytotoxicity was evaluated by ICP-OES and toxicity analysis of Mo, Br and Cs. We showed that the clusters did not affect seed germination but greatly inhibited plant growth. This inhibition was much more important when plants were treated with nanosized entities than with microsized cluster aggregates. In addition, nanosized clusters affected the root morphology in a different manner than microsized cluster aggregates, as shown by FE-SEM observations. The root penetration of the clusters was followed by secondary ion mass spectroscopy with high spatial resolution (NanoSIMS) and was also found to be much more important for treatments with nanosized clusters.

High spatial resolution grain orientation and strain mapping in thin films using polychromatic submicron x-ray diffraction

Science.gov (United States)

Tamura, N.; MacDowell, A. A.; Celestre, R. S.; Padmore, H. A.; Valek, B.; Bravman, J. C.; Spolenak, R.; Brown, W. L.; Marieb, T.; Fujimoto, H.; Batterman, B. W.; Patel, J. R.

2002-05-01

The availability of high brilliance synchrotron sources, coupled with recent progress in achromatic focusing optics and large area two-dimensional detector technology, has allowed us to develop an x-ray synchrotron technique that is capable of mapping orientation and strain/stress in polycrystalline thin films with submicron spatial resolution. To demonstrate the capabilities of this instrument, we have employed it to study the microstructure of aluminum thin film structures at the granular and subgranular levels. Due to the relatively low absorption of x-rays in materials, this technique can be used to study passivated samples, an important advantage over most electron probes given the very different mechanical behavior of buried and unpassivated materials.

Nuclear clustering - a cluster core model study

International Nuclear Information System (INIS)

Paul Selvi, G.; Nandhini, N.; Balasubramaniam, M.

2015-01-01

Nuclear clustering, similar to other clustering phenomenon in nature is a much warranted study, since it would help us in understanding the nature of binding of the nucleons inside the nucleus, closed shell behaviour when the system is highly deformed, dynamics and structure at extremes. Several models account for the clustering phenomenon of nuclei. We present in this work, a cluster core model study of nuclear clustering in light mass nuclei

Cluster fusion algorithm: application to Lennard-Jones clusters

DEFF Research Database (Denmark)

Solov'yov, Ilia; Solov'yov, Andrey V.; Greiner, Walter

2006-01-01

paths up to the cluster size of 150 atoms. We demonstrate that in this way all known global minima structures of the Lennard-Jones clusters can be found. Our method provides an efficient tool for the calculation and analysis of atomic cluster structure. With its use we justify the magic number sequence......We present a new general theoretical framework for modelling the cluster structure and apply it to description of the Lennard-Jones clusters. Starting from the initial tetrahedral cluster configuration, adding new atoms to the system and absorbing its energy at each step, we find cluster growing...... for the clusters of noble gas atoms and compare it with experimental observations. We report the striking correspondence of the peaks in the dependence of the second derivative of the binding energy per atom on cluster size calculated for the chain of the Lennard-Jones clusters based on the icosahedral symmetry...

Cluster fusion algorithm: application to Lennard-Jones clusters

DEFF Research Database (Denmark)

Solov'yov, Ilia; Solov'yov, Andrey V.; Greiner, Walter

2008-01-01

paths up to the cluster size of 150 atoms. We demonstrate that in this way all known global minima structures of the Lennard-Jones clusters can be found. Our method provides an efficient tool for the calculation and analysis of atomic cluster structure. With its use we justify the magic number sequence......We present a new general theoretical framework for modelling the cluster structure and apply it to description of the Lennard-Jones clusters. Starting from the initial tetrahedral cluster configuration, adding new atoms to the system and absorbing its energy at each step, we find cluster growing...... for the clusters of noble gas atoms and compare it with experimental observations. We report the striking correspondence of the peaks in the dependence of the second derivative of the binding energy per atom on cluster size calculated for the chain of the Lennard-Jones clusters based on the icosahedral symmetry...

Abdominal adipose tissue quantification on water-suppressed and non-water-suppressed MRI at 3T using semi-automated FCM clustering algorithm

Science.gov (United States)

Valaparla, Sunil K.; Peng, Qi; Gao, Feng; Clarke, Geoffrey D.

2014-03-01

Accurate measurements of human body fat distribution are desirable because excessive body fat is associated with impaired insulin sensitivity, type 2 diabetes mellitus (T2DM) and cardiovascular disease. In this study, we hypothesized that the performance of water suppressed (WS) MRI is superior to non-water suppressed (NWS) MRI for volumetric assessment of abdominal subcutaneous (SAT), intramuscular (IMAT), visceral (VAT), and total (TAT) adipose tissues. We acquired T1-weighted images on a 3T MRI system (TIM Trio, Siemens), which was analyzed using semi-automated segmentation software that employs a fuzzy c-means (FCM) clustering algorithm. Sixteen contiguous axial slices, centered at the L4-L5 level of the abdomen, were acquired in eight T2DM subjects with water suppression (WS) and without (NWS). Histograms from WS images show improved separation of non-fatty tissue pixels from fatty tissue pixels, compared to NWS images. Paired t-tests of WS versus NWS showed a statistically significant lower volume of lipid in the WS images for VAT (145.3 cc less, p=0.006) and IMAT (305 cc less, p1), but not SAT (14.1 cc more, NS). WS measurements of TAT also resulted in lower fat volumes (436.1 cc less, p=0.002). There is strong correlation between WS and NWS quantification methods for SAT measurements (r=0.999), but poorer correlation for VAT studies (r=0.845). These results suggest that NWS pulse sequences may overestimate adipose tissue volumes and that WS pulse sequences are more desirable due to the higher contrast generated between fatty and non-fatty tissues.

The Evolution of Total Phenolic Compounds and Antioxidant Activities during Ripening of Grapes (Vitis vinifera L., cv. Tempranillo Grown in Semiarid Region: Effects of Cluster Thinning and Water Deficit

Directory of Open Access Journals (Sweden)

Inmaculada Garrido

2016-11-01

Full Text Available A study was made of how water status (rainfed vs. irrigated and crop load (no cluster thinning vs. cluster thinning can together affect the grapes of Vitis vinifera cv. Tempranillo vines growing in a semiarid zone of Extremadura (Spain. The grapes were monitored at different stages of ripening, measuring the peroxidase (POX and superoxide dismutase (SOD antioxidant activities and the phenolic content (flavonoids and phenylpropanoids, together with other parameters. The irrigation regime was adjusted to provide 100% of crop evapotranspiration (ETc. The findings confirmed previous results that both thinning and water deficit advance ripening, while irrigation and high crop load (no thinning lengthen the growth cycle. The SOD activity remained practically constant throughout ripening in the thinned treatments and was always lower than in the unthinned treatments, an aspect which could have been the cause of the observed greater level of lipid peroxidation in the water deficit, thinned treatment. The nonspecific peroxidase activity was very low, especially in the thinned treatments. The effect of thinning was enhanced when combined with water deficit, inducing increases in phenylpropanoids and, above all, flavonoids at the harvest stage of ripening, while leaving the polyphenol oxidase activity (PPO unaffected.

A comparison between burn-out data for 19-rod cluster test-sections cooled by Freon-12 at 155 lb/in2 (abs), and by water at 1000 lb/in2 in vertical upflow

International Nuclear Information System (INIS)

Stevens, G.F.; Wood, R.W.

1966-01-01

Previous experiments on the Winfrith Freon Rig have produced scaling factors which relate these Freon experiments to the corresponding experiments in water with an accuracy of about 10%. It has also been found that the Freon rig is accurate, economical and easy to use. The scaling factors so obtained have now been tested against data for 19-rod clusters which had previously been tested at Columbia University. This report presents the results of the rod cluster tests in which comparison is made between Freon-12 and water for three test-sections which differ in the means of spacing the individual rods. All the test-sections were heated uniformly with respect to length, but had a radial flux depression of nominally 0.70/1.0. The results provide strong evidence that the scaling factor method using Freon-12 at 155 lb/in 2 (abs) is a useful technique for predicting the behaviour at burn-out of complicated test-sections cooled by boiling water at 1000 lb/in 2 with only one-eighteenth of the power required for the water experiment. In particular, the Freon tests reproduce closely the relative burn-out powers previously measured in water. It has also been found that repeated rebuilding of a nominally unchanged cluster from the same components can produce burn-out powers differing by ± 6%. This new result illustrates the power and value of the Freon technique. (author)

Assessment of the quality of water by hierarchical cluster and variance analyses of the Koudiat Medouar Watershed, East Algeria

Science.gov (United States)

Tiri, Ammar; Lahbari, Noureddine; Boudoukha, Abderrahmane

2017-12-01

The assessment of surface water in Koudiat Medouar watershed is very important especially when it comes to pollution of the dam waters by discharges of wastewater from neighboring towns in Oued Timgad, who poured into the basin of the dam, and agricultural lands located along the Oued Reboa. To this end, the multivariable method was used to evaluate the spatial and temporal variation of the water surface quality of the Koudiat Medouar dam, eastern Algeria. The stiff diagram has identified two main hydrochemical facies. The first facies Mg-HCO3 is reflected in the first sampling station (Oued Reboa) and in the second one (Oued Timgad), while the second facies Mg-SO4 is reflected in the third station (Basin Dam). The results obtained by the analysis of variance show that in the three stations all parameters are significant, except for Na, K and HCO3 in the first station (Oued Reboa) and the EC in the second station (Oued Timgad) and at the end NO3 and pH in the third station (Basin Dam). Q-mode hierarchical cluster analysis showed that two main groups in each sampling station. The chemistry of major ions (Mg, Ca, HCO3 and SO4) within the three stations results from anthropogenic impacts and water-rock interaction sources.

Asymmetric Top Rotors in Superfluid Para-Hydrogen Nano-Clusters

Science.gov (United States)

Zeng, Tao; Li, Hui; Roy, Pierre-Nicholas

2012-06-01

We present the first simulation study of bosonic clusters doped with an asymmetric top molecule. A variation of the path-integral Monte Carlo method is developed to study a para-water (pH_2O) impurity in para-hydrogen (pH_2) clusters. The growth pattern of the doped clusters is similar in nature to that of the pure clusters. The pH_2O molecule appears to rotate freely in the cluster due to its large rotational constants and the lack of adiabatic following. The presence of pH_2O substantially quenches the superfluid response of pH_2 with respect to the space fixed frame. We also study the behaviour of a sulphur dioxide (32S16O_2) dopant in the pH_2 clusters. For such a heavy rotor, the adiabatic following of the pH_2 molecules is established and the superfluid renormalization of the rotational constants is observed. The rotational structure of the SO_2-p(H_2)_N clusters' ro-vibrational spectra is predicted. The connection between the superfluid response respect to the external boundary rotation and the dopant rotation is discussed.

Mechanisms of submicron inclusion re-equilibration during host mineral deformation

Science.gov (United States)

Griffiths, Thomas; Habler, Gerlinde; Abart, Rainer; Rhede, Dieter; Wirth, Richard

2014-05-01

Both brittle and ductile deformation can facilitate re-equilibration of mineral inclusions. The presence of inclusions also influences stress and strain distribution in the host. The processes governing feedbacks between brittle deformation, ductile deformation, and inclusion re-equilibration have been studied using unique microstructures in Permian meta-pegmatite garnets from the Koralpe, Eastern Alps, Austria. Sampled almandine-spessartine garnets contain highly abundant submicron-sized inclusions, which originated during or subsequent to magmatic garnet growth. The Permian magmatic assemblages were affected by eclogite facies metamorphism during the Cretaceous tectono-metamorphic event. The meta-pegmatite garnet deformed crystal-plastically at this metamorphic stage (Bestmann et al. 2008) and the host-inclusion system was affected by partial recrystallization. Trails of coarser inclusions (1-10µm diameter) crosscut the magmatic submicron inclusion density zoning in the garnet, defining curviplanar geometrical surfaces in 3D. In 10-40µm broad 'bleaching zones' flanking inclusion trails, the original ≤1µm sized inclusions are not seen in the optical microscope or SEM, however inclusions <100nm are still abundant in TEM foils from these areas. From their microstructural characteristics it is inferred that the trails formed at sites of healed brittle cracks. FEG-microprobe data showed that inclusion-trails and associated bleaching zones can be formed isochemically, although some trails showed non-isochemical coarsening. In both cases no change in garnet major element composition was observed. EBSD mapping revealed two phenomena that were investigated by cutting targeted TEM foils. Firstly, bleaching zones are associated with systematic very low angle (ca. 0.5°) garnet lattice orientation changes along discrete boundaries. TEM foils transecting such a boundary show a lower concentration of dislocations than expected for the lattice rotation inferred from EBSD

Comprehensive cluster analysis with Transitivity Clustering.

Science.gov (United States)

Wittkop, Tobias; Emig, Dorothea; Truss, Anke; Albrecht, Mario; Böcker, Sebastian; Baumbach, Jan

2011-03-01

Transitivity Clustering is a method for the partitioning of biological data into groups of similar objects, such as genes, for instance. It provides integrated access to various functions addressing each step of a typical cluster analysis. To facilitate this, Transitivity Clustering is accessible online and offers three user-friendly interfaces: a powerful stand-alone version, a web interface, and a collection of Cytoscape plug-ins. In this paper, we describe three major workflows: (i) protein (super)family detection with Cytoscape, (ii) protein homology detection with incomplete gold standards and (iii) clustering of gene expression data. This protocol guides the user through the most important features of Transitivity Clustering and takes ∼1 h to complete.

Cluster-cluster correlations and constraints on the correlation hierarchy

Science.gov (United States)

Hamilton, A. J. S.; Gott, J. R., III

1988-01-01

The hypothesis that galaxies cluster around clusters at least as strongly as they cluster around galaxies imposes constraints on the hierarchy of correlation amplitudes in hierachical clustering models. The distributions which saturate these constraints are the Rayleigh-Levy random walk fractals proposed by Mandelbrot; for these fractal distributions cluster-cluster correlations are all identically equal to galaxy-galaxy correlations. If correlation amplitudes exceed the constraints, as is observed, then cluster-cluster correlations must exceed galaxy-galaxy correlations, as is observed.

CONSTRAINING CLUSTER PHYSICS WITH THE SHAPE OF X-RAY CLUSTERS: COMPARISON OF LOCAL X-RAY CLUSTERS VERSUS ΛCDM CLUSTERS

International Nuclear Information System (INIS)

Lau, Erwin T.; Nagai, Daisuke; Kravtsov, Andrey V.; Vikhlinin, Alexey; Zentner, Andrew R.

2012-01-01

Recent simulations of cluster formation have demonstrated that condensation of baryons into central galaxies during cluster formation can drive the shape of the gas distribution in galaxy clusters significantly rounder out to their virial radius. These simulations generally predict stellar fractions within cluster virial radii that are ∼2-3 times larger than the stellar masses deduced from observations. In this paper, we compare ellipticity profiles of simulated clusters performed with varying input physics (radiative cooling, star formation, and supernova feedback) to the cluster ellipticity profiles derived from Chandra and ROSAT observations, in an effort to constrain the fraction of gas that cools and condenses into the central galaxies within clusters. We find that local relaxed clusters have an average ellipticity of ε = 0.18 ± 0.05 in the radial range of 0.04 ≤ r/r 500 ≤ 1. At larger radii r > 0.1r 500 , the observed ellipticity profiles agree well with the predictions of non-radiative simulations. In contrast, the ellipticity profiles of simulated clusters that include dissipative gas physics deviate significantly from the observed ellipticity profiles at all radii. The dissipative simulations overpredict (underpredict) ellipticity in the inner (outer) regions of galaxy clusters. By comparing simulations with and without dissipative gas physics, we show that gas cooling causes the gas distribution to be more oblate in the central regions, but makes the outer gas distribution more spherical. We find that late-time gas cooling and star formation are responsible for the significantly oblate gas distributions in cluster cores, but the gas shapes outside of cluster cores are set primarily by baryon dissipation at high redshift (z ≥ 2). Our results indicate that the shapes of X-ray emitting gas in galaxy clusters, especially at large radii, can be used to place constraints on cluster gas physics, making it potential probes of the history of baryonic

Improved Bilayer Resist System Using Contrast-Enhanced Lithography With Water-Soluble Photopolymer

Science.gov (United States)

Sasago, Masaru; Endo, Masayuki; Hirai, Yoshihiko; Ogawa, Kazufurni; Ishihara, Takeshi

1986-07-01

A new water-soluble contract enhanced material, WSP (Water-soluble Photopolymer), has been developed. The WSP is composed of a mainpolymer and a photobleachable reagents. The mainpolymer is a water-soluble polymer mixed with pullulan (refined through biotechnological process) and polyvinyl-pyrolidone (PVP). The photo-bleachable reagent is of a diazonium compound gorup. The introduction of the mainpolymer and photobleach-able reagent mixture has improved filmity, gas transparency, photobleaching characteristics and solubility in alkaline which are essential to the device fabrication. Submicron photoresist patterns are successfully fabricated by a simple sequence of photolithography process. The WSP layer has been applied to the bilayer resist system--deep-UV portable conformable masking (PCM)--that is not affected by VLSI's topography, and is able to fabricate highly accurate pattern. The aqueous developable layer, PMGI, with high organic solvent resistance is used in the bottom layer. Therefore, no interfacial mixing with conventional positive resist top layer is observed. Furthermore, deep-UV exposure method has been used for the KrF excimer laser optical system in order to increase high throughput. From the experiments, it has been confirmed that good resist transfer profile can be realized by the use of WSP, and that the submicron resist patterns with high aspect-ratio can be developed on the nonplaner wafer with steps of up to 41m by the combination of the WSP with the PCM system. By this technology, has been improved the weak point: variation in the line width due to the thickness of contrast-enhanced layer when the CEL technology is applied, and dependency of both the finished resist profile and the line-width accuracy on the thickness of the top layer resist when the PCM system is adopted.

High energy density supercapacitors from lignin derived submicron activated carbon fibers in aqueous electrolytes

Science.gov (United States)

Hu, Sixiao; Zhang, Sanliang; Pan, Ning; Hsieh, You-Lo

2014-12-01

Highly porous submicron activated carbon fibers (ACFs) were robustly generated from low sulfonated alkali lignin and fabricated into supercapacitors for capacitive energy storage. The hydrophilic and high specific surface ACFs exhibited large-size nanographites and good electrical conductivity to demonstrate outstanding electrochemical performance. ACFs from KOH activation, in particular, showed very high 344 F g-1 specific capacitance at low 1.8 mg cm-2 mass loading and 10 mV s-1 scan rate in aqueous electrolytes. Even at relatively high scan rate of 50 mV s-1 and mass loading of 10 mg cm-2, a decent specific capacitance of 196 F g-1 and a remarkable areal capacitance of 0.55 F cm-2 was obtained, leading to high energy density of 8.1 Wh kg-1 based on averaged electrodes mass. Furthermore, over 96% capacitance retention rates were achieved after 5000 charge/discharge cycles. Such excellent performance demonstrated great potential of lignin derived carbons for electrical energy storage.

Analysis of functional failure mode of commercial deep sub-micron SRAM induced by total dose irradiation

International Nuclear Information System (INIS)

Zheng Qi-Wen; Cui Jiang-Wei; Zhou Hang; Yu De-Zhao; Yu Xue-Feng; Lu Wu; Guo Qi; Ren Di-Yuan

2015-01-01

Functional failure mode of commercial deep sub-micron static random access memory (SRAM) induced by total dose irradiation is experimentally analyzed and verified by circuit simulation. We extensively characterize the functional failure mode of the device by testing its electrical parameters and function with test patterns covering different functional failure modes. Experimental results reveal that the functional failure mode of the device is a temporary function interruption caused by peripheral circuits being sensitive to the standby current rising. By including radiation-induced threshold shift and off-state leakage current in memory cell transistors, we simulate the influence of radiation on the functionality of the memory cell. Simulation results reveal that the memory cell is tolerant to irradiation due to its high stability, which agrees with our experimental result. (paper)

The investigation of ferromagnetic resonance linewidth in Ni80Fe20 films with submicron rectangular elements

Directory of Open Access Journals (Sweden)

D. Zhang

2016-05-01

Full Text Available Patterned magnetic films with nano-scaled dots exhibit some special magnetic properties. In this paper, we investigate the in-plane shape anisotropy and the magnetization dynamic damping in permalloy (Ni80Fe20 arrays of submicron rectangular elements using ferromagnetic resonance (FMR. The FMR linewidth exhibits a dependence on the element size, and mainly comes from the contribution of the intrinsic damping. Also the contribution of two-magnon scattering plays an important role and is reduced with increasing aspect ratio. The damping coefficient decreases from 0.0129 to 0.0118 with the element length increasing from 300 nm to 1200 nm, and the theoretical calculation suggests that the change of damping results from the longitudinal and transverse interlayer spin current due to the spatially inhomogeneous magnetization dynamics.

Scalable Sub-micron Patterning of Organic Materials Toward High Density Soft Electronics.

Science.gov (United States)

Kim, Jaekyun; Kim, Myung-Gil; Kim, Jaehyun; Jo, Sangho; Kang, Jingu; Jo, Jeong-Wan; Lee, Woobin; Hwang, Chahwan; Moon, Juhyuk; Yang, Lin; Kim, Yun-Hi; Noh, Yong-Young; Jaung, Jae Yun; Kim, Yong-Hoon; Park, Sung Kyu

2015-09-28

The success of silicon based high density integrated circuits ignited explosive expansion of microelectronics. Although the inorganic semiconductors have shown superior carrier mobilities for conventional high speed switching devices, the emergence of unconventional applications, such as flexible electronics, highly sensitive photosensors, large area sensor array, and tailored optoelectronics, brought intensive research on next generation electronic materials. The rationally designed multifunctional soft electronic materials, organic and carbon-based semiconductors, are demonstrated with low-cost solution process, exceptional mechanical stability, and on-demand optoelectronic properties. Unfortunately, the industrial implementation of the soft electronic materials has been hindered due to lack of scalable fine-patterning methods. In this report, we demonstrated facile general route for high throughput sub-micron patterning of soft materials, using spatially selective deep-ultraviolet irradiation. For organic and carbon-based materials, the highly energetic photons (e.g. deep-ultraviolet rays) enable direct photo-conversion from conducting/semiconducting to insulating state through molecular dissociation and disordering with spatial resolution down to a sub-μm-scale. The successful demonstration of organic semiconductor circuitry promise our result proliferate industrial adoption of soft materials for next generation electronics.

Large area sub-micron chemical imaging of magnesium in sea urchin teeth.

Science.gov (United States)

Masic, Admir; Weaver, James C

2015-03-01

The heterogeneous and site-specific incorporation of inorganic ions can profoundly influence the local mechanical properties of damage tolerant biological composites. Using the sea urchin tooth as a research model, we describe a multi-technique approach to spatially map the distribution of magnesium in this complex multiphase system. Through the combined use of 16-bit backscattered scanning electron microscopy, multi-channel energy dispersive spectroscopy elemental mapping, and diffraction-limited confocal Raman spectroscopy, we demonstrate a new set of high throughput, multi-spectral, high resolution methods for the large scale characterization of mineralized biological materials. In addition, instrument hardware and data collection protocols can be modified such that several of these measurements can be performed on irregularly shaped samples with complex surface geometries and without the need for extensive sample preparation. Using these approaches, in conjunction with whole animal micro-computed tomography studies, we have been able to spatially resolve micron and sub-micron structural features across macroscopic length scales on entire urchin tooth cross-sections and correlate these complex morphological features with local variability in elemental composition. Copyright © 2015 Elsevier Inc. All rights reserved.

Convex Clustering: An Attractive Alternative to Hierarchical Clustering

Science.gov (United States)

Chen, Gary K.; Chi, Eric C.; Ranola, John Michael O.; Lange, Kenneth

2015-01-01

The primary goal in cluster analysis is to discover natural groupings of objects. The field of cluster analysis is crowded with diverse methods that make special assumptions about data and address different scientific aims. Despite its shortcomings in accuracy, hierarchical clustering is the dominant clustering method in bioinformatics. Biologists find the trees constructed by hierarchical clustering visually appealing and in tune with their evolutionary perspective. Hierarchical clustering operates on multiple scales simultaneously. This is essential, for instance, in transcriptome data, where one may be interested in making qualitative inferences about how lower-order relationships like gene modules lead to higher-order relationships like pathways or biological processes. The recently developed method of convex clustering preserves the visual appeal of hierarchical clustering while ameliorating its propensity to make false inferences in the presence of outliers and noise. The solution paths generated by convex clustering reveal relationships between clusters that are hidden by static methods such as k-means clustering. The current paper derives and tests a novel proximal distance algorithm for minimizing the objective function of convex clustering. The algorithm separates parameters, accommodates missing data, and supports prior information on relationships. Our program CONVEXCLUSTER incorporating the algorithm is implemented on ATI and nVidia graphics processing units (GPUs) for maximal speed. Several biological examples illustrate the strengths of convex clustering and the ability of the proximal distance algorithm to handle high-dimensional problems. CONVEXCLUSTER can be freely downloaded from the UCLA Human Genetics web site at http://www.genetics.ucla.edu/software/ PMID:25965340

A Study of Submicron Grain Boundary Precipitates in Ultralow Carbon 316LN Steels

Science.gov (United States)

Downey, S.; Han, K.; Kalu, P. N.; Yang, K.; Du, Z. M.

2010-04-01

This article reports our efforts in characterization of an ultralow carbon 316LN-type stainless steel. The carbon content in the material is one-third that in a conventional 316LN, which further inhibits the formation of grain boundary carbides and therefore sensitizations. Our primary effort is focused on characterization of submicron size precipitates in the materials with the electron backscatter diffraction (EBSD) technique complemented by Auger electron spectroscopy (AES). Thermodynamic calculations suggested that several precipitates, such as M23C6, Chi, Sigma, and Cr2N, can form in a low carbon 316LN. In the steels heat treated at 973 K (700 °C) for 100 hours, a combination of EBSD and AES conclusively identified the grain boundary precipitates (≥100 nm) as Cr2N, which has a hexagonal closed-packed crystallographic structure. Increases of the nitrogen content promote formation of large size Cr2N precipitates. Therefore, prolonged heat treatment at relatively high temperatures of ultralow carbon 316LN steels may result in a sensitization.

Thermomagnetic writing on deep submicron-patterned TbFe films by nanosecond current pulse

International Nuclear Information System (INIS)

You, Long; Kato, Takeshi; Tsunashima, Shigeru; Iwata, Satoshi

2009-01-01

This work studies the heating process for deep submicron-patterned TbFe films to be used in a thermally assisted perpendicular magnetic random access memory's writing scheme. The dependence of the heating power density with the current pulse width required for the successful writing was measured in the investigated range of 5-100 ns. In the case of long current pulse, the heat diffuses dominantly into substrate, which resulted in large variation of the required power/energy density with the patterned size. The power/energy densities required for writing increased as the junction area is reduced. While for the short current pulse width, the power/energy densities became rather independent on the size. The required power density for writing 0.38x0.28 μm 2 patterned films using the pulse width of 5 ns is experimentally estimated to be around P=4.7 mW/μm 2 , corresponding to the energy density of E=23 pJ/μm 2 , under an external field of 100 Oe

Detection of MM.-radiation with high current density submicron niobium-niobium Josephson junctions

International Nuclear Information System (INIS)

Daalmans, G.M.; Graauw, T. de; Lidholm, S.; Vliet, F. v.

1980-01-01

The rf-induced step heights in submicron niobium-niobium Josephson junctions are in good agreement with Russer theory at 230 and 240 GHz. At 115 and 460 GHz the agreement is less but still reasonably good. The junction noise without rf-bias is within a factor of two equal to the theoretical limit. With rf-bias applied it can be equal to the theoretical limit within a factor of two. The maximum conversion efficiency measured at 230 GHz was 0.18 and the lowest single side band mixer noise temperature at the same frequency was 380 K. Saturation effects are limiting the performance of the mixer. Improvements in eta and Tsub(M) of a factor of two can be expected by eliminating these saturation effects. The mixer which has been studied most extensively starting at 12-3-80 is still alive at 5-6-80 after many cooling cycles, storage at room temperature and soldering in and out of the dewar. The reliability of this type of junction cannot be questionable anymore. (orig.)

Dynamics of Neutral Cluster Growth and Cluster Ion Fragmentation for Toluene/Water, Aniline/Argon, and 4-Fluorostyrene/Argon Clusters: Covariance Mapping of the Mass Spectral Data

National Research Council Canada - National Science Library

Foltin, M

1998-01-01

.... To explore sensitivity of the parent ion/fragment ion correlation coefficient to cluster fragmentation, correlation coefficients are measured as a function of ionization photon energy as thresholds...

Cluster management.

Science.gov (United States)

Katz, R

1992-11-01

Cluster management is a management model that fosters decentralization of management, develops leadership potential of staff, and creates ownership of unit-based goals. Unlike shared governance models, there is no formal structure created by committees and it is less threatening for managers. There are two parts to the cluster management model. One is the formation of cluster groups, consisting of all staff and facilitated by a cluster leader. The cluster groups function for communication and problem-solving. The second part of the cluster management model is the creation of task forces. These task forces are designed to work on short-term goals, usually in response to solving one of the unit's goals. Sometimes the task forces are used for quality improvement or system problems. Clusters are groups of not more than five or six staff members, facilitated by a cluster leader. A cluster is made up of individuals who work the same shift. For example, people with job titles who work days would be in a cluster. There would be registered nurses, licensed practical nurses, nursing assistants, and unit clerks in the cluster. The cluster leader is chosen by the manager based on certain criteria and is trained for this specialized role. The concept of cluster management, criteria for choosing leaders, training for leaders, using cluster groups to solve quality improvement issues, and the learning process necessary for manager support are described.

A lyophilized etoposide submicron emulsion with a high drug loading for intravenous injection: preparation, evaluation, and pharmacokinetics in rats.

Science.gov (United States)

Chen, Hao; Shi, Shuai; Zhao, Mingming; Zhang, Ling; He, Haibing; Tang, Xing

2010-12-01

To develop a submicron emulsion for etoposide with a high drug loading capacity using a drug-phospholipid complex combined with drug freeze-drying techniques. An etoposide-phospholipid complex (EPC) was prepared and its structure was confirmed by X-ray diffraction and differential scanning calorimetry analysis. A freeze-drying technique was used to produce lyophilized etoposide emulsions (LEPE), and LEPE was investigated with regard to their appearance, particle size, and zeta potential. The pharmacokinetic study in vivo was determined by the UPLC/MS/MS system. It showed that EPC significantly improved the liposolubility of etoposide, indicating a high drug loading intravenous emulsion could be easily prepared by EPC. Moreover, the obtained loading of etoposide in the submicron emulsion was 3.0 mg/mL, which was three times higher than that of the previous liquid emulsions. The optimum cryoprotectant was trehalose (15%) in freeze-drying test. The median diameter, polydispersity index, and zeta potential of the optimum formulation of LEPE were 226.1 ± 5.1 nm, 0.107 ± 0.011, and -36.20 ± 1.13 mV, respectively. In addition, these parameters had no significant change during 6 months storage at 4 ± 2°C. The main pharmacokinetic parameters exhibited no significant differences between LEPE and etoposide commercial solution except for area under the concentration-time curve and clearance. The stable etoposide emulsion with a high drug loading was successfully prepared, indicating the amount of excipients such as the oil phase and emulsifiers significantly decreased following administration of the same dose of drug, effectively reducing the metabolism by patients while increasing their compliance. Therefore, LEPE has a great potential for clinical applications.

Improving service delivery of water, sanitation, and hygiene in primary schools: a cluster-randomized trial in western Kenya.

Science.gov (United States)

Alexander, Kelly T; Dreibelbis, Robert; Freeman, Matthew C; Ojeny, Betty; Rheingans, Richard

2013-09-01

Water, sanitation, and hygiene (WASH) programs in schools have been shown to improve health and reduce absence. In resource-poor settings, barriers such as inadequate budgets, lack of oversight, and competing priorities limit effective and sustained WASH service delivery in schools. We employed a cluster-randomized trial to examine if schools could improve WASH conditions within existing administrative structures. Seventy schools were divided into a control group and three intervention groups. All intervention schools received a budget for purchasing WASH-related items. One group received no further intervention. A second group received additional funding for hiring a WASH attendant and making repairs to WASH infrastructure, and a third group was given guides for student and community monitoring of conditions. Intervention schools made significant improvements in provision of soap and handwashing water, treated drinking water, and clean latrines compared with controls. Teachers reported benefits of monitoring, repairs, and a WASH attendant, but quantitative data of WASH conditions did not determine whether expanded interventions out-performed our budget-only intervention. Providing schools with budgets for WASH operational costs improved access to necessary supplies, but did not ensure consistent service delivery to students. Further work is needed to clarify how schools can provide WASH services daily.

Ionic cluster size distributions of swollen nafion/sulfated beta-cyclodextrin membranes characterized by nuclear magnetic resonance cryoporometry.

Science.gov (United States)

Jeon, Jae-Deok; Kwak, Seung-Yeop

2007-08-16

Nafion/sb-CD membranes were prepared by mixing 5 wt% Nafion solution with H+-form sulfated beta-cyclodextrin (sb-CD), and their water uptakes, ion exchange capacities (IECs), and ionic cluster size distributions were measured. Gravimetric and thermogravimetric measurements showed that the water uptake of the membranes increased with increases in their sb-CD content. The IECs of the membrane were measured with acid-base titration and found to increase with increases in the sb-CD content, reaching 0.96 mequiv/g for NC5 ("NCx" denotes a Nafion/sb-CD composite membrane containing x wt% of sb-CD). The cluster-correlation peaks and ionic cluster size distributions of the water-swollen membranes were determined using small-angle X-ray scattering (SAXS) and 1H nuclear magnetic resonance (NMR) cryoporometry, respectively. The SAXS experiments confirmed that increases in the sb-CD content of the membranes shifted the maximum SAXS peaks to lower angles, indicating an increase in the cluster correlation peak. NMR cryoporometry is based on the theory of the melting point depression, Delta Tm, of a liquid confined within a pore, which is dependent on the pore diameter. The melting point depression was determined by analyzing the variation of the NMR signal intensity with temperature. Our analysis of the intensity-temperature (IT) curves showed that the ionic cluster size distribution gradually became broader with increases in the membrane sb-CD content due to the increased water content, indicating an increase in the ionic cluster size. This result indicates that the presence of sb-CD with its many sulfonic acid sites in the Nafion membranes results in increases in the ionic cluster size as well as in the water uptake and the IEC. We conclude that NMR cryoporometry provides a method for determining the ionic cluster size on the nanometer scale in an aqueous environment, which cannot be obtained using other methods.

Lifting to cluster-tilting objects in higher cluster categories

OpenAIRE

Liu, Pin

2008-01-01

In this note, we consider the $d$-cluster-tilted algebras, the endomorphism algebras of $d$-cluster-tilting objects in $d$-cluster categories. We show that a tilting module over such an algebra lifts to a $d$-cluster-tilting object in this $d$-cluster category.

Revisit the landscape of protonated water clusters H+(H2O)n with n = 10-17: An ab initio global search

Science.gov (United States)

Shi, Ruili; Li, Keyao; Su, Yan; Tang, Lingli; Huang, Xiaoming; Sai, Linwei; Zhao, Jijun

2018-05-01

Using a genetic algorithm incorporated with density functional theory, we explore the ground state structures of protonated water clusters H+(H2O)n with n = 10-17. Then we re-optimize the isomers at B97-D/aug-cc-pVDZ level of theory. The extra proton connects with a H2O molecule to form a H3O+ ion in all H+(H2O)10-17 clusters. The lowest-energy structures adopt a monocage form at n = 10-16 and core-shell structure at n = 17 based on the MP2/aug-cc-pVTZ//B97-D/aug-cc-pVDZ+ZPE single-point-energy calculation. Using second-order vibrational perturbation theory, we further calculate the infrared spectra with anharmonic correction for the ground state structures of H+(H2O)10-17 clusters at the PBE0/aug-cc-pVDZ level. The anharmonic correction to the spectra is crucial since it reproduces the experimental results quite well. The extra proton weakens the O-H bond strength in the H3O+ ion since the Wiberg bond order of the O-H bond in the H3O+ ion is smaller than that in H2O molecules, which causes a red shift of the O-H stretching mode in the H3O+ ion.

Data Clustering

Science.gov (United States)

Wagstaff, Kiri L.

2012-03-01

On obtaining a new data set, the researcher is immediately faced with the challenge of obtaining a high-level understanding from the observations. What does a typical item look like? What are the dominant trends? How many distinct groups are included in the data set, and how is each one characterized? Which observable values are common, and which rarely occur? Which items stand out as anomalies or outliers from the rest of the data? This challenge is exacerbated by the steady growth in data set size [11] as new instruments push into new frontiers of parameter space, via improvements in temporal, spatial, and spectral resolution, or by the desire to "fuse" observations from different modalities and instruments into a larger-picture understanding of the same underlying phenomenon. Data clustering algorithms provide a variety of solutions for this task. They can generate summaries, locate outliers, compress data, identify dense or sparse regions of feature space, and build data models. It is useful to note up front that "clusters" in this context refer to groups of items within some descriptive feature space, not (necessarily) to "galaxy clusters" which are dense regions in physical space. The goal of this chapter is to survey a variety of data clustering methods, with an eye toward their applicability to astronomical data analysis. In addition to improving the individual researcher’s understanding of a given data set, clustering has led directly to scientific advances, such as the discovery of new subclasses of stars [14] and gamma-ray bursts (GRBs) [38]. All clustering algorithms seek to identify groups within a data set that reflect some observed, quantifiable structure. Clustering is traditionally an unsupervised approach to data analysis, in the sense that it operates without any direct guidance about which items should be assigned to which clusters. There has been a recent trend in the clustering literature toward supporting semisupervised or constrained