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  1. Magnetic structure of molecular magnet Fe[Fe(CN)6]·4H2O

    Indian Academy of Sciences (India)

    Amit Kumar; S M Yusuf

    2004-08-01

    We have studied the magnetic structure of Fe[Fe(CN)6]·4H2O, prepared by precipitation method, using neutron diffraction technique. Temperature dependent DC magnetization study down to 4.2 K shows that the compound undergoes from a high temperature disordered (paramagnetic) to an ordered magnetic phase transition at 22.6 K. Rietveld analysis of neutron diffraction pattern at 60 K (in its paramagnetic phase) revealed a face centred cubic structure with space group Fm3m. The structure contains three-dimensional network of straight Fe3+ –C≡N–Fe3+ chains along the edges of the unit cell cube. Fe3+ ions occupy 4 (0, 0, 0) and 4 (1/2, 1/2, 1/2) positions. Fe3+ (0, 0, 0) is surrounded octahedrally by six nitrogen atoms and Fe3+ (1/2, 1/2, 1/2) is surrounded octahedrally by six carbon atoms. Magnetic Rietveld refinement of neutron diffraction data at 11 K shows a ferromagnetic coupling between the two inequivalent Fe3+ sites. Refinement yielded an ordered moment of 4.4(6) and 0.8(6) B per Fe ion located at (0, 0, 0) and (1/2, 1/2, 1/2), respectively. Ordered moments are found to align along the face diagonal. The observed net moment from low temperature neutron diffraction study is consistent with DC magnetization results.

  2. Geothermal characterization in Sumatra and North Sulawesi using geothermometer T 18OSO4-H2O

    International Nuclear Information System (INIS)

    Determination of geothermal reservoir temperature of surface manifestation in Sumatra and Kotamobagu-North Sulawesi has been done using geothermometer isotope T18OSO4-H2O. SBY-3 (Sibayak) well temperature has also been determined as reference. Geothermometer T18OSO4-H2O method is performed by analyzing isotope 18O of H2O and 34S of sulphate ion (SO4) dissolved in the hot fluid. The value of temperature is determined using Mizutani Rafter formulation. The temperature determination result of boiling spring in Sumatra (Tambang Sawah, Waipanas, Rantau Dadap and Sarula) indicated that the temperature is above 200oC with the deep equilibrium fluid characteristic, where as the temperature of the non boiling spring indicates lower temperature (150oC) and the fluid characteristic is mixing. (authors)

  3. Synthesis,Crystal Structure,Thermal Decomposition and Sensitivity Properties of [Zn(AZT)4(H2O)2](PA)2·4H2O and [Zn(AZT)2(H2O)4](HTNR)2·4H2O

    Institute of Scientific and Technical Information of China (English)

    CUI Yan; ZHANG Tong-Lai; ZHANG Jian-Guo; YANG Li

    2008-01-01

    Two new coordination compounds [Zn(AZT)4(H2O)2](PA)2·4H2O and [Zn(AZT)2(H2O)4](HTNR)2·4H2O have been prepared by using AZT(3-azido-1,2,4-triazole)as ligands,PA-(picrate)or HTNR-(anion formed by the deprotonation of one of the two hydroxyl-groups of 2,4,6-trinitroresorcinol)as outer anions.The X-ray crystallographic data show that the central zinc(Ⅱ)ion is coordinated by four N atoms of four AZT molecules and two O atoms of two H2O molecules in [Zn(AZT)4(H2O)2](PA)2·4H2O.In [Zn(AZT)2(H2O)4](HTNR)2·4H2O,six coordination-atoms come from two N atoms of two AZT molecules and four O atoms of four H2O molecules.The coordina-tion sites of AZT ligands in both compounds are always 4-N atoms of the triazole rings.H2O molecules play vital roles in the formation of hydrogen bonds,which contribute to the construction of the crystal structures of both compounds.The offset face-to-face π-π stacking interactions existing in the crystal of [Zn(AZT)4(H2O)2](PA)2·4H2O also contribute to the formation and stability of its crystal structure.TG-DTG and DSC analysis results show that the thermal decomposition processes of [Zn(AZT)2(H2O)4](HTNR)2·4H2O are milder than those of [Zn-(AZT)4(H2O)2](PA)2·4H2O due to the more coordination H2O molecules and less AZT ligands in the molecular unit of the former compound.Sensitivity tests reveal that [Zn(AZT)4(H2O)2](PA)2·4H2O has sensitive nature towards heat,whereas [Zn(AZT)2(H2O)4](HTNR)2·4H2O is insensitive;both compounds are insensitive to friction and im-pact.

  4. Reductive Cyclodimerization of Arylidenecyanoacetates Promoted by Sm/InCl3 ·4H2O System in Aqueous Media

    Institute of Scientific and Technical Information of China (English)

    Hua Yue WU; Jin Chang DING; Le Ping FANG; Jing GAO

    2004-01-01

    Promoted by active indium produced in situ by Sm/InCl3 · 4H2O system, arylidenecyano- acetates undergo reductive cyclodimerization to afford cyclopentamine derivatives with high stereoselectivity under mild conditions in aqueous media.

  5. Is UO2HPO4,4H2O a proton conductor

    International Nuclear Information System (INIS)

    HUP (UO2HPO4,4H2O) was washed with water until decomposition. The composition was followed by X-ray diffraction. The experiments show that HUP can be washed free of mother liquor without destruction. The washing time necessary is several days. Washing with water for several weeks converts HUP to a new phase. The ac-conductivity of discs of HUP washed free of mother liquor was 1.3x10-4 ohm-1cm-1, an order of magnitude lower than values reported in literature for discs of unwashed HUP. The ac-conductivity of a cell containing the washing solution after it was equilibrated with HUP was measured. Replacement of some of the liquid with HUP taken from the same washing experiment diminished the conductivity of the cell. The conductivity of HUP is therefore lower than the conductivity of the liquid (1.3x10-3 ohm-1cm-1). The authors conclude that the high conductivities of HUP reported in literature are caused by adhering liquid, and do not reflect intrinsic conductivity of the material. (Auth.)

  6. Synthesis and Thermodynamic Properties of MgO·B2O3·4H2O

    Institute of Scientific and Technical Information of China (English)

    LIU,Zhi-Hong(刘志宏); GAO,Shi-Yang(高世扬); HU,Man-Cheng(胡满成); XIA,Shu-Ping(夏树屏)

    2002-01-01

    A new magnesium borate MgO@ B2O3 @ 4H2O was synthesized by the method of phase transformation of double salt and characterized by XRD, IR spectra and TG. The structural formula of this compound was Mg[B2O(OH)6] @H2O. The enthalpy of solution of MgO@B2O3@4H2O in HCl (1.0492 mol@ L-1) was determined. With the incorporation of the standard molar enthalpies of formation of MgO (s), H3BO3(s), and H2O (Ⅰ),the standard molar enthalpy of formation of - (3135.31 ±1.68) kJ@ mol-1 of MgO@B2O3@4H2O was obtained. Thermodynamic properties of this compoumd were also calculated by group contribution method.

  7. Enhancement of atmospheric H2SO4/H2O nucleation: organic oxidation products versus amines

    Directory of Open Access Journals (Sweden)

    T. Berndt

    2013-06-01

    Full Text Available Atmospheric H2SO4/H2O nucleation influencing effects have been studied in the flow tube IfT-LFT (Institute for Tropospheric Research – Laminar Flow Tube at 293 ± 0.5 K and a pressure of 1 bar using synthetic air as the carrier gas. The presence of a possible background amine concentration in the order of 107–108 molecule cm−3 throughout the experiments has to be taken into account. In a first set of investigations, ozonolysis of olefins (tetramethylethylene, 1-methyl-cyclohexene, α-pinene and limonene for close to atmospheric concentrations, served as the source of OH radicals and possibly other oxidants initiating H2SO4 formation starting from SO2. The oxidant generation is inevitably associated with the formation of a series of organic oxidation products arising from the parent olefins. These products (first generation mainly showed no clear effect on the number of nucleated particles within a wide range of experimental conditions for H2SO4 concentrations higher than ~107 molecule cm−3. A comparison of the results of two different particle counters (50% cut-off size: about 1.5 nm or 2.5–3 nm suggested that the early growth process of the nucleated particles was not significantly influenced by the organic oxidation products. An additional, H2SO4-independent process of particle (nano-CN formation was observed in the case of α-pinene and limonene ozonolysis for H2SO4 concentrations smaller than ~10 7 molecule cm−3. Furthermore, the findings confirm the existence of an additional oxidant for SO2 beside OH radicals, very likely stabilized Criegee Intermediate (sCI. In the case of the ozonolysis of tetramethylethylene, the H2SO4 measurements in the absence and presence of an OH radical scavenger were well described by modelling using recently obtained kinetic data for the sCI reactivity in this system. A second set of experiments has been performed in the presence of added amines (trimethylamine, dimethylamine, aniline and pyridine in

  8. InCl3.4H2O Catalyzed Aldol Condensation of Cycloalkanones with Aromatic Aldehydes

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    InCl3·4H2O catalyzes the cross-aldol condensation of cycloalkanones with aromatic aldehydes in sealed tube under solvent free condition to afford an efficient method for the synthesis of α, α-bis(substituted)benzylidenecycloalkanones.

  9. Microwave spectra of the SiH4-H2O complex: A new sort of intermolecular interaction

    Science.gov (United States)

    Kawashima, Yoshiyuki; Suenram, Richard D.; Hirota, Eizi

    2016-09-01

    Microwave spectral patterns observed for the silane-water complex were found much different from those of the methane-water complex. The SiH4-H2O complex is likely to have a tightly bound structure. The effective rotational and centrifugal distortion constants: B = 3621.1193 (45) MHz and DJ = 49.84 (30) kHz led to the distance between the Si and O atoms in the complex to be 3.3 Å, much shorter than the C and O separation in the CH4-H2O of 3.7 Å, and to the silane-water stretching force constant and stretching frequency to be 2.88 N/m and 65 cm-1, respectively, which are to be compared with 1.52 N/m and 55 cm-1 of the CH4-H2O. The characteristic features of the spectra observed for the main species 28SiH4-H2O are common to those of isotopic species: 29SiH4-H2O, 30SiH4-H2O, 28SiH4-H218O, 28SiH4-D2O, 29SiH4-D2O, 30SiH4-D2O, 28SiH4-HDO, 29SiH4-HDO, 30SiH4-HDO, 28SiD4-H2O, 28SiD4-D2O, and 28SiD4-HDO. The observed spectra also indicate that the silane executes a threefold internal rotation about one of its four Si-H bonds, while the C2 symmetry axis of the water is bent away from the internal-rotation axis. An internal axis method analysis yielded an estimate of the internal-rotation potential barrier V3 to be 140 ± 50 cm-1, and those based on diagonalization of a principal axis method Hamiltonian matrix and on the extended internal axis method resulted in V3 ranging from 180 to 100 cm-1, depending on the isotopic species studied. All the measurements were done by using a pulsed nozzle Fourier transform microwave spectrometer, and the spectral assignments were made with the aid of the Stark effect, which yielded the dipole moment to be 1.730 (10) D. Transitions in higher energy states of the SiH4 internal rotation were observed, clearly resolved from the main lines, when the carrier gas was replaced from Ar to Ne.

  10. [Bi2Cl10(H2-Norf)4(H2O)8] where H-Norf is Norfloxacin(R)%[Bi2Cl10(H2-Norf)4(H2O)8](H-Norf是诺氟沙星)

    Institute of Scientific and Technical Information of China (English)

    李咏华; 熊仁根

    2005-01-01

    The crystal structure of [Bi2Cl10(H2-Norf)4(H2O)s] (1) comprises [H2-Norf]+ cations and [Bi2Cl10]4- anions,that are loosely associated via H-bonding interactions, as well as water molecules that also participate in H-bond-ing interactions. Strong blue-fluorescent emission of 1 at solid state is observed at the room temperature. CCDC:238237.

  11. Solubility study and point of zero charge of studtite (UO2O2·4H2O)

    International Nuclear Information System (INIS)

    Highlights: • The variation of the studtite solubility with pH was determined. • A studtite solubility product log Ks0 = −2.7 is proposed. • The point of zero charge of studtite was determined to be 4.0. - Abstract: The knowledge of the characteristics of the U(VI)-peroxide chemical system is of importance because of the relevance of the uranyl peroxide solid phases studtite (UO2O2·4H2O) or metastudtite (UO2O2·2H2O) as uranyl secondary solid phases during the leaching of the spent nuclear fuel as well as to the formation in alkaline waters of soluble nanoscale uranyl peroxo cage clusters. In this work, the solubility of studtite was determined for the first time as a function of pH (from 3 to 11) by means of studtite undersaturation experiments. The results obtained showed a V-shaped solubility curve, which was modelled considering the uranyl complexes formation constants (database of the Nuclear Energy Agency, NEA) and recently published formation constants of uranium hydroxo-peroxo-complexes. The best fit of the model to the experimental solubility data was obtained with log Ks0 = −2.7 ± 0.2 for the studtite solubility reaction: UO2O2·4H2O(s)+2H+⇆UO22++4H2O+H2O2 On the other hand, the so-called immersion methodology was used in order to determine the pHpzc of studtite, which resulted to be 4.0 ± 0.2. This value would corroborate a sorption mechanism based on electrostatic interactions described for previously published sorption data of cations (Cs+, Sr2+) on studtite

  12. Dwornikite, (Ni,Fe)SO4.H2O, a member of the kieserite group from Minasragra, Peru.

    Science.gov (United States)

    Milton, C.; Evans, H.T.; Johnson, R.G.

    1982-01-01

    A new nickel sulphate monohydrate is described from V-sulphide ore from Minasragra; it occurs associated with patronite (VS2) with various sulphates, sulphur and bitumen. Dwornikite forms fine-grained white aggregates mixed with other oxidation products. Indexed X-ray powder data are tabulated; strongest lines 3.342(100) , 4.732(70), 3.024(70), 4.754(50), 3.293(35), 2.491(35) A; a 6.839, b 7.582, c 7.474 A, beta 117.85o; space group C2/c. XRF gave NiO 39.0, FeO 9.3, SO3 42.4, = 90.7; Dcalc. 3.34 g/cm3; mean refr. ind. approx 1.63. Unit-cell data for the synthetic end-member compounds NiSO4.H2O and FeSO4.H2O and new X-ray powder data for retgersite (NiSO4.6H2O) are given. The name is for E. J. Dwornik, mineralogist with the U.S. Geological Survey.-R.A.H.

  13. Thermodynamics of the formation of sulfuric acid dimers in the binary (H2SO4-H2O and ternary (H2SO4-H2O-NH3 system

    Directory of Open Access Journals (Sweden)

    A. Kürten

    2015-05-01

    Full Text Available Sulfuric acid is an important gas influencing atmospheric new particle formation (NPF. Both the binary (H2SO4-H2O system, and the ternary system involving ammonia (H2SO4-H2O-NH3 may be important in the free troposphere. An essential step in the nucleation of aerosol particles from gas-phase precursors is the formation of a dimer, so an understanding of the thermodynamics of dimer formation over a wide range of atmospheric conditions is essential to describe NPF. We have used the CLOUD chamber to conduct nucleation experiments for these systems at temperatures from 208 to 248 K. Neutral monomer and dimer concentrations of sulfuric acid were measured using a Chemical Ionization Mass Spectrometer (CIMS. From these measurements dimer evaporation rates in the binary system were derived for temperatures of 208 and 223 K. We compare these results to literature data from a previous study that was conducted at higher temperatures but is in good agreement with the present study. For the ternary system the formation of H2SO4 • NH3 is very likely an essential step in the formation of sulfuric acid dimers, which were measured at 210, 223, and 248 K. We estimate the thermodynamic properties (dH and dS of the H2SO4 • NH3 cluster using a simple heuristic model and the measured data. Furthermore, we report the first measurements of large neutral sulfuric acid clusters containing as many as 10 sulfuric acid molecules for the binary system using Chemical Ionization-Atmospheric Pressure interface-Time Of Flight (CI-APi-TOF mass spectrometry.

  14. Activity coefficients in electrolyte mixtures. HCl + ThCl4 + H2O for 5-55 degree C

    International Nuclear Information System (INIS)

    The emf of the cell without liquid junction (A) was used to study the HCl + ThCl4 + H2O mixed electrolyte system, where (A) is Pt, H2(g,1 atm)|Hcl(mB)|AgCl,Ag. The emf was measured for solutions at constant total ionic strengths of 0.006, 0.008, 0.01, 0.25, 0.5, 1.0, 2.0, and 3.0 mol.kg-1 and at temperatures ranging from 5 to 55 degree C. The mean activity coefficients of HCl in the mixtures were calculated using the Nernst equation. Two detailed treatments are given of the data for 25 degree C. In the first, the Harned equations were fitted to the activity coefficient data using least-squares regression techniques. Results show that the quadratic equation is adequate for the full range of YB to 0.9 for I ≤ 2.0 mol.kg-1 but only for smaller YB at I = 3.0. Second, an ion-interaction (Pitzer) equation treatment is given in which experimental isopiestic measurements, solubility, and the activity coefficient data are analyzed and the necessary parameters developed for the H+-Th4+-Cl--H2O system. 26 refs., 2 figs., 6 tabs

  15. Synthesis and Crystal Structure of Cu2 (pba) (bpy) 2 Cl2·4H2O

    Institute of Scientific and Technical Information of China (English)

    朱志成; 毛新平; 徐正; 黄小荥

    2000-01-01

    A new copper complex, Cu2 (pba)(bpy)2Cl2·4H2O (here pba was pro-pylenebis (oxamic acid), bpy was bipyridine), was synthesized. Crystal structure of thetitle complex was determined. It belongs to the tetragonal system, molecular formulaCu2Cl2Oi0N6C27H32, Mr = 798. 58, space group P4t212, a = b = 9. 484(4), c =35.918(9) A, V = 3235(2) A3, Dx = 1. 64gcm-3 and F(000) = 1568, μ =1. 546mm 1 for Z = 4. The crystal structure was solved by direct methods for final R =0.048 and Rω, = 0.060 for 1992 observed reflections with I >3a (I). The complex hasa C2 symmetry. A chloride anion, two nitrogen atoms from bipyridine and two oxygenatoms from the oxamide carbonyl and carboxyl coordinated to the CuⅡ ion forming asquare pyramidal geometry. In each molecule, two bpy are almost parallel.

  16. Synthesis and Structure of a Novel Macrocyclic Complex [Cd2(phen)4(phth)2]·4H2O

    Institute of Scientific and Technical Information of China (English)

    2005-01-01

    A novel complex [Cd2(phen)4(phth)2]·4H2O has been synthesized by the reaction of H2phth(phthalic acid) and phen(1,10-phenanthroline) with Cd(Ⅱ) in ethanol-water solution. X-ray crystal structure analysis shows it crystallizes in triclinic, space group P1 with a = 10.619(3), b =12.560(4), c = 12.651(4) A, α = 98.775(5), β = 109.035(5), γ = 113.576(5)°, C32H24CdN4O6, Mr=672.95, V= 1381.7(7) A3, Rint = 0.0358, Z= 2, Dc= 1.618 g/cm3, μ = 0.845 mm-1, -6 ≤h≤13, -15≤k ≤13, -15≤l≤14, F(000) = 680, S = 1.038, R = 0.0480 and wR = 0.0849 for 3992 observed reflections (I > 2σ(Ⅰ)). Phth bridges Cd(Ⅱ) to form a macrocyclic compound, and a 2D supramolecular motif is formed through hydrogen bonds and π-π interaction.

  17. A unified equation for calculating methane vapor pressures in the CH4-H2O system with measured Raman shifts

    Science.gov (United States)

    Lu, W.; Chou, I.-Ming; Burruss, R.C.; Song, Y.

    2007-01-01

    A unified equation has been derived by using all available data for calculating methane vapor pressures with measured Raman shifts of C-H symmetric stretching band (??1) in the vapor phase of sample fluids near room temperature. This equation eliminates discrepancies among the existing data sets and can be applied at any Raman laboratory. Raman shifts of C-H symmetric stretching band of methane in the vapor phase of CH4-H2O mixtures prepared in a high-pressure optical cell were also measured at temperatures between room temperature and 200 ??C, and pressures up to 37 MPa. The results show that the CH4 ??1 band position shifts to higher wavenumber as temperature increases. We also demonstrated that this Raman band shift is a simple function of methane vapor density, and, therefore, when combined with equation of state of methane, methane vapor pressures in the sample fluids at elevated temperatures can be calculated from measured Raman peak positions. This method can be applied to determine the pressure of CH4-bearing systems, such as methane-rich fluid inclusions from sedimentary basins or experimental fluids in hydrothermal diamond-anvil cell or other types of optical cell. ?? 2007 Elsevier Ltd. All rights reserved.

  18. Synthesis and crystal structure of the [Co2(Nicotinamide)4(C4H9COO)4(H2O)] complex

    International Nuclear Information System (INIS)

    The [Co2L4(C4H9COO)4(H2O)] coordination compound of cobalt(II) valerate with nicotinamide (L) is synthesized and studied by IR spectroscopy. The crystal structure of the synthesized compound is determined. The crystals are triclinic, and the unit cell parameters are as follows: a = 10.2759(10) A, b = 16.3858(10) A, c = 16.4262(10) A, α = 100.538(10) deg., β = 101.199(10) deg., γ = 90.813 (10) deg., Z = 2, and space group P1-bar. The structural units of the crystal are dimeric molecular complexes in which pairs of cobalt atoms are linked by triple bridges formed by oxygen atoms of two bidentately coordinated valerate anions and a water molecule. The octahedral coordination of each cobalt atom is complemented by the pyridine nitrogen atoms of two nicotinamide ligands and the oxygen atom of the monodentate valerate group. The hydrocarbon chains of the valerate anions are disordered over two or three positions each

  19. InCl3·4H2O Promoted Green Preparation of Xanthenedione Derivatives in Ionic Liquids

    Institute of Scientific and Technical Information of China (English)

    HU Xue-yuan; ZHANG Xin-ying; FAN Xue-sen; WANG Jian-ji

    2004-01-01

    Xanthenediones derivatives have attracted considerable interests in recent times because they constitute a structural unit in a number of natural products1 and have been used as versatile synthons due to the inherent reactivity of the inbuilt pyran ring2. The conventional syntheses of xanthenediones were acid or base catalyzed condensation of appropriate active methylene carbonyl compounds with aldehydes3. However, many of these procedures involved longer reaction times,low yields and side reactions of aldehydes. In recent years, room temperature ionic liquids (RTILs) have been used as novel green reaction media4. Considering that InCl3 is an efficient Lewis acid catalyst used in promoting many organic reactions, especially in several condensation processes, we herein wish to report a very simple and green method for the preparation of poly-hydrogenated xanthenediones through InCl3·4H2O promoted cascade reaction of aldehydes and 5,5-dimethyl-l,3-cyclohexanedione in ionic liquid,1-butyl-3-methylimidazolium tetrafluoroborate ([bmim][BF4]). The preparative process presented here is operationally simple, environmentally benign and has the advantage of enhanced atom utilization. Furthermore, the solvent and the catalyst used can be recovered easily and reused efficiently.

  20. Mahlmoodite, FeZr(PO4).4H2O, a new iron zirconium phosphate mineral from Wilson Springs, Arkansas

    Science.gov (United States)

    Milton, C.; McGee, J.J.; Evans, H.T.

    1993-01-01

    Small (phosphate tetrahedrate, FeZr(PO4)2.4H2O. This new mineral, named mahlmoodite, occurs as spherules of radiating fibers usually perched on crystals of pyroxene in vugs. The optical and crystallographic properties of mahlmoodite are described. -after Authors

  1. Synthesis, structure refinement and characterization of tetrahydrated acid gadolinium diphosphate HGdP2O7.4H2O

    International Nuclear Information System (INIS)

    Synthesis and single crystal structure are reported for a new gadolinium acid diphosphate tetrahydrate HGdP2O7.4H2O. This salt crystallizes in the monoclinic system, space group P21/n, with the following unit-cell parameters: a=6.6137(2)A, b=11.4954(4)A, c=11.377(4)A, β=87.53(2)o and Z=4. Its crystal structure was refined to R=0.0333 using 1783 reflections. The corresponding atomic arrangement can be described as an alternation of corrugated layers of monohydrogendiphosphate groups and GdO8 polyhedra parallel to the (1-bar 01) plane. The cohesion between the different diphosphoric groups is provided by strong hydrogen bonding involving the W4 water molecule. IR and Raman spectra of HGdP2O7.4H2O confirm the existence of the characteristic bands of diphosphate group in 980-700cm-1 area. The IR spectrum reveals also the characteristic bands of water molecules vibration (3600-3230cm-1) and acidic hydrogen ones (2340cm-1). TG and DTA investigations show that the dehydration of this salt occurs between 79 and 900 deg. C. It decomposes after dehydration into an amorphous phase. Gadolinium diphosphate Gd4(P2O7)3 was obtained by heating HGdP2O7.4H2O in a static air furnace at 850 deg. C for 48h

  2. An EPR study of the phase transitions and Gd3+ zero-field splitting parameters in RbR(SO4)2.4H2O (R = Er, Dy, Pr, Nd, Sm, Eu)

    International Nuclear Information System (INIS)

    X-band (∼9.6 GHz) electron paramagnetic resonance measurements were carried out on Gd3+-doped RbEr(SO4)2.4H2O and RbDy(SO4)2.4H2O single crystals in the 4.2-295 K temperature range, and on Gd3+-doped RbPr(SO4)2.4H2O, RbNd(SO4)2.4H2O, RbSm(SO4)2.4H2O and RbEu(SO4)2.4H2O single crystals in the 4.2-110 K range. Gd3+ room-temperature spin-Hamiltonian parameters were estimated in RbR(SO4)2.4H2O samples with R = Er, Dy. The following phase transitions undergone by the various host crystals were found to occur: three second-order phase transitions in RbDy(SO4)2.4H2O at 260.3 K, 226.9 K and 65.4 K, and second-order and first-order phase transitions in RbEr(SO4)2.4H2O at 228.1 and 68.8 K, respectively. In addition, there were observed first-order phase transitions in each of RbNd(SO4)2.4H2O (at 72.1 K), RbSm(SO4)2.4H2O (at 70.3 K) and RbEu(SO4)2.4H2O (at 79.4 K), and two in RbPr(SO4)2.4H2O (at 71.4 and 9.7 K) crystals, in the 4.2-110 K range, in addition to those reported previously in the 110-295 K range. Systematics of the various phase transitions occurring in RbR(SO4)2.4H2O (R = Pr, Nd, Sm, Er, Dy, Eu) single crystals in the temperature range 4.2-295 K, and those of Gd3+ zero-field splitting parameters at room temperature, have been deduced. (author)

  3. Et2NH2C6H3(CO23SnBr2.4H2O: SYNTHESIS AND INFRARED STUDY

    Directory of Open Access Journals (Sweden)

    DAOUDA NDOYE

    2014-01-01

    Full Text Available The title compound has been obtained on allowing [C6H3(CO23(Et2NH23] to react with SnBr4. The molecular structure of Et2NH2C6H3(CO23SnBr2.4H2O has been determined on the basis of the infrared data. The suggested structure is a dimer in which each tin atom is hexacoordinated by two chelating C6H3(CO233- anions and two Br atoms. Cy2NH2+cations are involved through hydrogen bonds with non-coordinating CO2 groups. The suggested structure is a cage.

  4. Synthesis, structural investigation and thermal properties of a novel manganese complex Mn2(DAT)2Cl4(H2O)4 (DAT = 1,5-diaminotetrazole)

    International Nuclear Information System (INIS)

    A novel manganese complex Mn2(DAT)2Cl4(H2O)4, where DAT is 1,5-diaminotetrazole, was synthesized by the reaction of manganese(II) chloride tetrahydrate and 1,5-diaminotetrazole (DAT) in ethanol, and characterized by elemental analysis, FT-IR spectroscopy. The crystal structure was determined through X-ray single crystal diffraction. The molecular unit of Mn2(DAT)2Cl4(H2O)4 has a distorted octahedral structure, containing two central manganese cations, which coordinated by a mono-dentate terminal chloride, a bulky DAT ligand and two water molecules, and linked by two bidentate bridging chloride ligands. There are two main exothermic peaks and one endothermic peak in the thermal decomposition process, investigated by differential scanning calorimetry (DSC) and thermo-gravimetric analysis (TGA), the final residue of the title compound at 600 deg. C is MnO. The kinetic parameters of the endothermic process and two main exothermic processes were studied by applying the Kissinger's and Ozawa-Doyle's methods.

  5. Antioxidative protective effect of icariin on the FeSO4/H 2O 2-damaged human sperm based on confocal raman micro-spectroscopy.

    Science.gov (United States)

    Huang, Zhan-Sen; Xiao, Heng-Jun; Qi, Tao; Hu, Zhi-Ming; Li, Hao; Chen, Di-Ling; Xu, Ya-Lin; Chen, Jun

    2014-10-01

    Oxidative stress is implicated in male infertility and significantly higher reactive oxygen species are detected in 25% of infertile males. Although different agents of various alternative medicines, including traditional Chinese medicine, have been tried with varying success, evidence remains limited on whether and how much herbs or supplements might help increase the anti-oxidant ability of the sperm. This study examined the anti-oxidative effects of icariin, a flavonoid isolated from Herba Epimedii, on the human sperm. We prepared the FeSO4/H2O2-damaged human sperms, which were co-cultured with icariin in vitro, and then observed the changes of the sperm by employing Raman micro-spectroscopy. The results showed that Raman mapping with a 514 nm excitation laser allowed clear differentiation of the nucleus, neck, and, in particular, the mitochondria-rich middle piece of a human sperm cell. The effect of icariin on different organelles of the sperm was quantified by localized spectral Raman signatures obtained within milli-seconds, and icariin could keep the "Raman fingerprint" of the human sperm the same as the control groups, suggesting that icariin could protect the human sperm from being damaged by FeSO4/H2O2. Icariin may serve as a tonifying and replenishing agent of herbal origin for enhancing reproductive functions. PMID:25318889

  6. A measurement system for continuous observations of CO2, CH4, H2O and CO onboard passenger aircraft

    Science.gov (United States)

    Gerbig, Christoph; Filges, Annette; Franke, Harald; Klaus, Christoph; Chen, Huilin

    2013-04-01

    integration in mid 2013. The aim is to have seven systems operational within four years, providing for long-term GHG observations with near-global coverage. To enable robust and automated operation of the IAGOS GHG package over six-month deployment periods, numerous technical issues had to be addressed. An inlet system, designed as virtual impactor to eliminate sampling of larger aerosols, ice particles, and water droplets, provides additional positive ram-pressure to ensure operation without an upstream sampling pump. Furthermore, no sample drying is required, as the simultaneously measured water vapor mole fraction is used to correct for dilution and spectroscopic effects. This also enables the collection of science-quality water vapor measurements throughout the atmosphere. To allow for trace gas measurements to be fully traceable to WMO scales, a two-standard calibration system has been designed and tested that periodically provides calibration gas to the instrument during flight and on ground for each six-month deployment period. We present results from recent test flights and laboratory tests that document the performance for GHG and water vapor measurements. Furthermore, future applications of the IAGOS-GHG data stream, provided in near-real-time via SatCom to the weather prediction centres, will be discussed.

  7. Laboratory studies of H2SO4/H2O binary homogeneous nucleation from the SO2+OH reaction: evaluation of the experimental setup and preliminary results

    Directory of Open Access Journals (Sweden)

    M. Kulmala

    2008-08-01

    Full Text Available Binary homogeneous nucleation (BHN of sulphuric acid and water (H2SO4/H2O is one of the most important atmospheric nucleation processes, but laboratory observations of this nucleation process are very limited and there are also large discrepancies between different laboratory studies. The difficulties associated with these experiments include wall loss of H2SO4 and uncertainties in estimation of H2SO4 concentration ([H2SO4] involved in nucleation. We have developed a new laboratory nucleation setup to study H2SO4/H2O BHN kinetics and provide relatively constrained [H2SO4] needed for nucleation. H2SO4 is produced from the SO2+OH→HSO3 reaction and OH radicals are produced from water vapor UV absorption. The residual [H2SO4] were measured at the end of the nucleation reactor with a chemical ionization mass spectrometer (CIMS. Wall loss factors (WLFs of H2SO4 were estimated by assuming that wall loss is diffusion limited and these calculated WLFs were in good agreement with simultaneous measurements of the initial and residual [H2SO4] with two CIMSs. The nucleation zone was estimated from numerical simulations based on the measured aerosol sizes (particle diameter, Dp and [H2SO4]. The measured BHN rates (J ranged from 0.01–220 cm−3 s−1 at the initial and residual [H2SO4] from 108−1010 cm−3, a temperature of 288 K and relative humidity (RH from 11–23%; J increased with increasing [H2SO4] and RH. J also showed a power dependence on [H2SO4] with the exponential power of 3–8. These power dependences are consistent with other laboratory studies under similar [H2SO4] and RH, but different from atmospheric field observations which showed that particle number concentrations are often linearly dependent on [H2SO4]. These results, together with a higher [H2SO4] threshold (108–109 cm−3 needed to produce the unit J measured from the laboratory studies compared to the atmospheric conditions (106–107 cm−3, imply that H2SO4/H2O BHN alone is

  8. Structure of hafnium and ammonium double sulphate Hf(SO4)2x2(NH4)2SO4x4H2O

    International Nuclear Information System (INIS)

    X-ray structural study of hafnium and ammonium double sulfate (NH4)4Hf(SO4)4 x 4H2O (diffractometer ''Syntex R2'', lambda Mo, heavy atom method, anisotropic specification R=0.052 according to 2330 reflections) has been carried out. The crystals are monoclinic, a=22.264, b=7.356, c=18.065 A, #betta#=138.33 deg, gr. C2/c. The structure is built of complex anions [Hf(SO4)4 x (H2O)2]4-, cations NH4+ and water molecules. Hf - O distances in hafnium dodecahedron are 2.067-2.283 A. Valent angles of the compounds are presented

  9. Study of the crystal structure of double ammonium hafnium sulfate of the (NH4)4Hf(SO4)4x4H2O composition

    International Nuclear Information System (INIS)

    Two new double compounds of (NH4)2Hf(SO4)3x2H2O and (NH4)4Hf(SO4)4x4H2O have been studied. The second compound which forms needle transparent crystals of monoclinic singony, has been studied by the X-ray analysis. The unit cell parametres are as follows: a = 18.12(3), b = 14.89(3), c = 7.25(3) A, γ = 95.5 deg (5), spatial group P2/b, N=4. The first structure may be described as an islet structure. Besides basic valent bonds, it contains numerous intermolecular contacts and hydrogen bonds formed by water molecules and ammonium ions

  10. Synthesis and Crystal Structure of a Novel Complex [Ag(NIT3Py)3]·((ClO4)(H2O)

    Institute of Scientific and Technical Information of China (English)

    ZHANG Chen-Xi; LIAO Dai-Zheng; JIANG Zong-Hui; YAN Shi-Ping

    2005-01-01

    A novel complex [Ag(NIT3Py)3]·((ClO4)(H2O) has been synthesized and structurally characterized by X-ray diffraction method. It crystallizes in the rhombohedral system, space group R3 with a = 15.8227(17), b = 15.8227(17), c = 31.445(3) (A),γ = 120°, V = 6817.8(12) (A)3, Dc = 1.370 g/cm3, Z = 6, μ= 0.566 mm-1, Mr = 937.18, F(000) = 2916, R = 0.0715, wR = 0.2115 and GOF = 1.086. The structure consists of Ag(NIT3Py)3+ cation moiety, one water molecule and one perchloric ion. The Ag(I) ion is in a trigonal planar coordination environment formed by three nitrogen atoms from three NIT3Py ligand molecules.

  11. Solubility measurement and solid-liquid equilibrium model for the ternary system MgBr2 + MgSO4 + H2O at 288.15 K

    Directory of Open Access Journals (Sweden)

    Li Dan

    2014-06-01

    Full Text Available The solubility of magnesium minerals and the refractive index of the ternary system MgBr2 + MgSO4 + H2O at 288.15 K were investigated using an isothermal dissolution method. It was found that there are two invariant points in the phase diagram and the solubility isotherm of this ternary system consists of three branches, corresponding to equilibrium crystallization of Epsomite (MgSO4·7H2O, Eps, hexahydrite (MgSO4·6H2O, Hex and magnesium bromide hexahydrate (MgBr2·6H2O, Mb. Neither solid solutions nor double salts were found. The refractive indices calculated from empirical equation are in good agreement with the experimental data. Combining the results from solubility measurements with the single-salt parameters for MgBr2 and MgSO4, and the mixed ion-interaction parameter θBr,S0(4, the parameter ψMg,Br,S0(4 at 288.15 K was fitted using the Pitzer theory and Harvie-Weare (HW approach. In addition, the average equilibrium constants of the stable equilibrium solids at 288.15 K were obtained by a method using the activity product constant. A chemical model, which combined the Pitzer parameters and the average equilibrium constants, was constructed to calculate the solid + liquid equilibria in the ternary system MgBr2 + MgSO4 + H2O at 288.15 K. The model agreed well with the equilibrium solubility data for the magnesium salts.

  12. Bobjonesite, V4+ O (SO4) (H2O)3, a new mineral species from Temple Mountain, Emery County, Utah, U.S.A

    International Nuclear Information System (INIS)

    Bobjonesite, V4+ O (SO4) (H2O)3, is a new mineral species from Temple Mountain, Emery County, Utah, U.S.A. It occurs as blue-green crusts and efflorescences in fractures in a fossil (Triassic) tree; individual crystals are 1 mm and are intimately intergrown. Bobjonesite hydrates very easily, and is unstable in all but the driest atmosphere. Its structure was determined on a crystal of bobjonesite; however, the physical properties, optical properties and X-ray powder-diffraction pattern were recorded on the synthetic equivalent, and an electron-microprobe analysis was not possible. Bobjonesite has a pale blue streak, a vitreous luster and no observable fluorescence under ultraviolet light. It has no cleavage or parting. The Mohs hardness is ∼1, and the calculated density is 2.28 g/cm3. Bobjonesite is biaxial positive, with α 1.555(2), β 1.561(1), γ 1.574(2), 2V(obs.) = 72(1)o, 2V(calc.) = 69o; it is non-pleochroic, X = b, Y ∼ a, the angle between Z and c ∼ 19o (in β obtuse). Bobjonesite is monoclinic, space group P21/n, cell dimensions from single-crystal data: a 7.3940(5), b 7.41 11(3), c 12.0597(9) A, β 106.55(1)o, V 633.5(1) A3, Z = 4. The strongest seven lines in the X-ray powder-diffraction pattern [d in A(I)(hkl)] are as follows: 5.795(100)(002), 3.498(90)(112), 3.881(48)((1-03), 5.408(37) (101), 4.571(20)(012), 6.962(11)((1-01) and 6.254(11)(011). The chemical formula was derived from crystal-structure analysis; the end-member formula is V O (SO4) (H2O)3. The crystal structure of bobjonesite was refined to an R index of 3.6% for 1105 observed (|Fo| 5σF) reflections measured with an automated four-circle X-ray diffractometer using MoKα X-radiation. There is one V site occupied by V4+ and surrounded by three O atoms and three (H2O) groups in an octahedral arrangement, with one short vanadyl bond (1.577 A), four similar equatorial bonds (), and one longer V-O bond (2.278 A) traps to the vanadyl bond. The structure consists of isolated [V4+2 O2 (H2O

  13. Impact of H2SO4/H2O coating and ice crystal size on radiative properties of sub-visible cirrus

    Directory of Open Access Journals (Sweden)

    P. Räisänen

    2006-01-01

    Full Text Available Recent laboratory experiments showed that at conditions resembling those near the tropopause region, small ice particles can be coated by a liquid H2SO4/H2O over-layer formed after the freezing of diluted sulfuric acid/water aerosol drops. Here, idealized radiative transfer tests are conducted to evaluate the impact that such an over-layer would have on the radiative effects produced by sub-visible cirrus clouds (SVCs. Spherical particle shape is assumed to keep the problem tractable. The calculations show that the over-layer increases both the shortwave (SW and longwave (LW cloud radiative effects (CRE, but the impact is small: ~0.02 W m−2, or even less, for the total (LW+SW CRE at the top of the atmosphere. For the smallest ice particles, for which the over-layer is thickest, the fractional change in CRE can, however, reach ~20% for the SW CRE and over 50% for the LW CRE. The dependence of LW and SW CRE on particle size is also studied in the paper. Calculations for spherical and spheroidal uncoated ice particles show that even for high, optically thin cirrus, the total CRE can be negative, if the diameter of the particles is smaller than about 3–4 μm. Apart from the SVCs, this result could be relevant for contrail cirrus clouds, which are believed to consist of large numbers of very small ice particles.

  14. Impact of H2SO4/H2O coating and ice crystal size on radiative properties of sub-visible cirrus

    Directory of Open Access Journals (Sweden)

    M. J. Molina

    2006-06-01

    Full Text Available Recent laboratory experiments showed that at conditions resembling those near the tropopause region, small quasi-spherical ice particles can be coated by a liquid H2SO4/H2O over-layer formed after the freezing of diluted sulfuric acid/water aerosol drops. Here, idealized radiative transfer tests are conducted to evaluate the impact that such an over-layer would have on the radiative effects produced by sub-visible cirrus clouds (SVCs. The calculations show that the over-layer increases both the shortwave (SW and longwave (LW cloud radiative effects (CRE, but the impact is small: ~0.02 W m-2, or even less, for the total (LW+SW CRE at the top of the atmosphere. For the smallest ice particles, for which the over-layer is thickest, the fractional change in CRE can, however, reach ~20% for the SW CRE and over 50% for the LW CRE. The dependence of LW and SW CRE on particle size is also considered in the paper. Calculations for spherical uncoated ice particles show that even for high, optically thin cirrus clouds, the total CRE can be negative, if the diameter of the particles is smaller than about 3–4 µm. Apart from the SVCs, this result could be relevant for contrail cirrus clouds, which are believed to consist of large numbers of very small ice particles.

  15. Crystal Structure of a Threedimensional Coordination Polymer {[Ca3(μ5-OOCCH2OCH2COO)3(H2O)4]·4H2O}n

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    A novel three-dimensional coordination polymer, {[Ca3(μ5-OOCCH2OCH2COO)3(H2O)4]·4H2O}n, has been synthesized with oxydiacetate as bridge ligand and structurally determined by X-ray crystallography. The crystal belongs to monoclinic, space group C2/c with a = 17.805(2), b = 9.3923(12), c = 17.255(2)(A), β = 107.838(5)°, V = 2746.8(6) (A)3, Mr = 660.58, C12H28Ca3O23, Dc = 1.597 g/cm3, μ = 0.695 mm-1, Z = 4, F(000) = 1376, GOOF = 1.027, R = 0.0303 and wR = 0.0660. In the complex there are two coordination modes for Ca(Ⅱ) ions, one coordinated by three μ5-OOCCH2OCH2COO2- bridge ligands together with two H2O molecules, and the other by five μ5-OOCCH2OCH2COO2- bridge ligands. In both coordination modes each Ca(Ⅱ) ion assumes a distorted dipentapyramidal CaO7 geometry; whereas each oxydiacetate is coordinated with five Ca(Ⅱ) ions and acts as a pentdentates bridge ligand.

  16. Single-crystal structure of coordination polymer [Nd2(C8H5NO4)3·4H2O]∞

    Institute of Scientific and Technical Information of China (English)

    2003-01-01

    The single-crystal structure of the coordination polymer [Nd2(C8H5NO4)3@4H2O]∞ with rhombus-channels is reported in this paper. There are two crystallographically independent Nd(Ⅲ) ions, and each Nd(Ⅲ) ion is in the eight-coordinated environment. Seven of eight oxygen atoms are from six 5-aminoisophthalic acid ligands, the other oxygen atom is given by coordination water. Carboxyl groups link two Nd(Ⅲ) ions using η1,1 and η1,3 modes. Two carboxyl groups from ligands chelate Nd(Ⅲ) ion to form four-mem- bered rings. Crystal data: Triclinic, space group a = 1.03680(5) nm, b = 1.66934(15) nm, c = 0.88221(14) nm, α = 99.754(2)°, β = 111.169(4)°,β = 85.400(4)(. Some ligands linking metal Nd(Ⅲ) ions parallel to ab plane form molecu- lar ladders, and the others linking molecular ladders result in rhombus channels along c-axis. These coordinated water molecules and amino groups are pendent in the channels.

  17. Synthesis and Structure of anti-Configuration Complex [Cu(tssb)2]·2[(H3O)Cl]·4H2O

    Institute of Scientific and Technical Information of China (English)

    张淑华; 蒋毅民; 刘峥; 周忠远

    2004-01-01

    The title complex [Cu(tssb)2]·2[(H3O)Cl]·4H2O (C18H34Cl2CuN2O14S2) (tssb = taurine salicylaldehyde Schiff base) has been synthesized by the reaction of taurine salicylaldehyde Schiff base (tssb) and copper acetate in water-ethanol. Its single-crystal structure was determined by X-ray diffraction method. The crystal structure belongs to triclinic, space group P with a = 0.7407(1), b = 1.3329(3), c = 1.5736(3)nm, α = 103.800(4), β = 95.030(4), γ = 104.416(4)°, Mr = 701.06, V = 1.4433(5) nm3, Z = 2, Dc = 1.613 g/cm3, μ = 1.153 mm-1 and F(000) = 726. The compound is an infinitely expanding three-dimensional network connected with hydrogen bonds. The Cu(Ⅱ) atom is coordinated by two nitrogen and two oxygen atoms to form a distorted planar coordination compound which adopts anti-configuration because two sulfonic acid groups are positioned diagonally on a plane.

  18. Structure of Hexakis(imidazole)nickel(Ⅱ) Nitrate Water Solvate:[Ni(Im)6](No3)2·4H2O

    Institute of Scientific and Technical Information of China (English)

    肖海连; 张书圣; 建方方; 赵朴素

    2002-01-01

    Crystal structure of the title compound,[Ni(Im)6](NO3)2·4H2O(Im=imidazole),was determined by X-ray crystallographic analysis.The crystal structure consists of idscrete Ni-(Im)62 cation,NO3- anion and four uncoordinated water molecules.It crystallizes in the hexagonal system,space group P63,with lattice parameters a=b=0.9003(2)nm,c=2.1034(4)nm,and Z=2.The Ni(Ⅱ)ion is centro-symmet-ric octahedron geometry with the NiN6 core.Six imidszole molecules are coordinated to each nickel(Ⅱ)atom through its tertiary nitrogen aton.The short and long bond distandces of Ni-N are 0.2059(6) and 0.2204(7)nm, respectively.In the solid state.[Ni(Im)6]2 ,H2O moieties and nitrate anions form the three dimensional hydrogen bonds netowrk which stabitzes the crystal structure.

  19. Etch rates for (100) gallium arsenide using aqueous H2SO4:H2O2 and aqua regia based etchants

    International Nuclear Information System (INIS)

    Etch rate experiments were carried out for (100) GaAs using etching solutions of H2SO4 :H2O2 :H2 O (3:1:1, 3:1:15), HCl:HNO3 (3:1), HCl:HNO3 :H2 O (1:1:1) and HCl:HNO3 :glycerol (with various dilutions of glycerol). Several differences were seen for the (100) plane compared to previous results for other crystal orientations. The sulphuric acid solutions showed much lower activation energies for etching the (100) plane. The HCl:HNO3 :glycerol solutions showed considerably lower etch rates for the (100) plane, probably indicating that they etch GaAs anisotropically. For a 1:1:2 solution of HCl:HNO3 :glycerol a decrease in the etch rate of (100) GaAs was observed in the presence of stirring. This is the opposite result to what is commonly assumed for this polishing etchant. It indicates that the main polishing process attributed to this etchant is not present, and in fact, the polishing quality of the etchant is probably limited by the etching process which is present. 14 refs., 8 figs

  20. Syntheses, characterization, and luminescence of two lanthanide complexes [Ln2(acetate)6(H2O)4]·4H2O (Ln=Tb(1), Sm(2))

    Institute of Scientific and Technical Information of China (English)

    YU Qiongyan; ZHOU Xiuxia; LIU Maosheng; CHEN Jianqiao; ZHOU Zhengyuan; YIN Xia; CAI Yuepeng

    2008-01-01

    Two dinuclear compounds [Ln2(acetate)6(H2O)4]·4H2O (Ln=Tb(1), Sm(2)) were obtained by the hydrothermal reaction of Ln2O3 with malonic acid at 150 ℃. Both compounds were characterized by elemental analyses, infrared spectra, and single crystal X-ray diffraction. The results showed that complexes 1 and 2 were isomorphous and crystallize in triclinic space group P(-1). The coordination geometry around Ln(III) ions in the complexes 1 and 2 was a distorted tricapped trigonal prism with a nine coordination. In the crystal, the molecular organization was further stabilized by well-defined weak hydrogen bonding interactions between the neutral dinuclear molecular units that led to the formation of a three-dimensional network. The fluorescence properties of the two complexes 1 and 2 in organic solvents were also studied. The results show that the ligand acetate favored energy transfer to the emitting energy level of Tb(III) in complex 1. Some factors that influence the fluorescent intensity were also discussed in the article.

  1. Synthesis and crystal structure of hexaaquamagnesium hydrogen phosphododecatungstate tetrahydrate [Mg(H2O)6][HPW12O40].4H2O

    International Nuclear Information System (INIS)

    Crystals suitable for X-ray structure analysis were obtained after the slow evaporation of the reaction mixture containing equimolar quantities of magnesium chloride and dodecatungstophosphoric acid aqueous solution insuring pH of the solution between 1.0 and 1.2. This simple synthetic route yielded stability of Keggin anion and high quality [Mg(H2O)6][HPW12O40].4H2O single crystals. The obtained compound belongs to the group of heteropoly compounds and its structure is composed of Keggin [PW12O40]3- anions, [Mg(H2O)6]2+ cations and lattice water molecules. Zigzag arrangement of Keggin anions along c-axis creates irregular channels occupied by [Mg(H2O)6]2+ cations and lattice H2O molecules. The calculation of the total potential solvent volume indicated the presence of 4.1 lattice H2O lattice molecules per formula unit, which is in agreement with the here presented structural model. The position of one lattice water molecule is well defined, while each of three other molecules is statistically distributed over two locations. Hydrogen bonds involve all coordinated and lattice H2O molecules, as well as some oxygen atoms from the Keggin anion. (copyright 2007 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  2. A two-dimensional yttrium phthalate coordination polymer, [Y4(H2O)2(C8H4O4)6]∞, exhibiting different coordination geometries

    Indian Academy of Sciences (India)

    A Thirumurugan; Srinivasan Natarajan

    2003-10-01

    A hydrothermal reaction of a mixture of Y(NO3)3, 1,2-benzenedicarboxylic acid (1,2-BDC) and NaOH gives rise to a new yttrium phthalate coordination polymer, [Y4(H2O)2(C8H4O4)6]∞, I. The Y ions in I are present in four different coordination environments with respect to the oxygen atoms (CN6 = octahedral, CN7 = pentagonal bipyramid, CN8 = dodecahedron and CN9 =capped square antiprism). The oxygen atoms of the 1,2-BDC are fully deprotonated, and show variations in their connectivity with Y atoms. The Y atoms themselves are connected through their vertices forming infinite Y-O-Y one-dimensional chains. The Y-O-Y chains are cross-linked by the 1,2-BDC anions forming a corrugated layer structure. The layers are supported by favourable $\\ldots$ interactions between the benzene rings of the 1,2-BDC anions. The variations in the coordination environment of the Y atoms and the presence of Y-O-Y interactions along with the favourable $\\ldots$ interactions between the benzene rings from different layers are noteworthy structural features. Crystal data: triclinic, space group = -1 (no. 2), = 12.6669 (2), = 13.8538 (2), = 16.0289 Å, = 75.20 (1), = 69.012 (1), = 65.529 (1)°, = 2371.28 (7) Å3, calc = 1.922 g cm-1, (MoK) = 4.943 mm-1. A total of 9745 reflections collected and merged to give 6566 unique reflections (int = 0.0292) of which 5252 with > 2() were considered to be observed. Final 2 = 0.0339, 2 = 0.0724 and =1.036 were obtained for 704 parameters.

  3. Laboratory studies of H2SO4/H2O binary homogeneous nucleation from the SO2+OH reaction: evaluation of the experimental setup and preliminary results

    Directory of Open Access Journals (Sweden)

    F. R. Kameel

    2008-04-01

    Full Text Available We have developed a new laboratory nucleation setup to study binary homogeneous nucleation (BHN of sulphuric acid and water (H2SO4/H2O. Here we provide a detailed evaluation of this new experimental setup and also discuss our preliminary results by comparing with other laboratory studies. H2SO4 is produced from the SO2+OH →HSO3 reaction and OH radicals are produced from water vapor UV absorption. The residual H2SO4 concentrations ([H2SO4] are measured at the end of the fast flow nucleation reactor with a chemical ionization mass spectrometer. The measured BHN rates (J ranged from 0.02 and 550 cm−3 s−1 at the residual [H2SO4] from 108 to 1010 cm−3, a temperature of 288 K and relative humidity (RH from 6 to 23%; J increased with increasing [H2SO4] and RH. J also showed a power dependence on [H2SO4] with the exponential power of 3 to 8. These results are consistent with other laboratory studies under similar [H2SO4] and RH, but different from atmospheric field observations which showed that particle number concentrations are often linearly dependent on [H2SO4]. Both particle sizes and number concentrations increased with increasing [H2SO4], RH, and nucleation time, consistent with the predictions from nucleation theories. Particle growth rates were estimated between 28 to 127 nm h−1, much higher than those seen from atmospheric field observations, because of the higher [H2SO4] used in our study. While these experimental results demonstrate a validation of our laboratory setup, there are also technical difficulties associated with nucleation studies, including wall loss and H2SO4 measurements.

  4. 三元体系NaBr-Na2SO4-H2O 和 NaBr-KBr-H2O 373 K相平衡%Phase Equilibria of Two Ternary Systems NaBr-Na2SO4-H2O and NaBr-KBr-H2O at 373 K

    Institute of Scientific and Technical Information of China (English)

    桑世华; 崔瑞芝; 胡咏霞

    2014-01-01

    针对川西盆地富硼钾溴地下卤水组成,采用等温溶解平衡法研究了三元体系 NaBr-Na2SO4-H2O 和NaBr-KBr-H2O在373 K时的相平衡,测定了373 K条件下平衡溶液的溶解度和密度,根据实验数据绘制相应的相图和密度图。研究发现:两个三元体系在373 K条件下均属于简单共饱和型,无复盐及固溶体生成。相图中均有一个共饱和点,2个平衡固相结晶区和2条单变量曲线。在三元体系NaBr-Na2SO4-H2O中,平衡固相分别为:NaBr和Na2SO4,三元体系NaBr-KBr-H2O相应的平衡固相分别为:NaBr和KBr。并简单讨论了密度的变化规律。%Phase equilibria of two ternary systems NaBr-Na2SO4-H2O and NaBr-KBr-H2O at 373 K were studied by an isothermal solution saturation method. The solubility and density of these systems were determined experimentally and related phase diagrams were obtained. The results show that the two systems are both of simple type with no complex salts or solid solutions formed. Both of the phase diagrams show that they have one eutectic point, two univariant curves and two regions of crystallization. The solid phase in NaBr-Na2SO4-H2O is cpmposited of sodium bromide(NaBr) and sodium sulfate(Na2SO4), while sodium bromide(NaBr) and potassium bromide(KBr) are the components of the solid phase of NaBr-KBr-H2O. Density change of the two systems was discussed.

  5. EPR study of Gd3+-doped RbR(SO4)2·4H2O (R=Pr,Nd,Sm,Eu) single crystals: Phase transitions and spin-Hamiltonian parameters

    International Nuclear Information System (INIS)

    Extensive EPR measurements were carried out in the temperature range 100 endash 300 K. The room-temperature data indicate that Gd3+ ions substitute equally for R3+ ions at the two magnetically inequivalent sites in the unit cell, and that the site symmetry of the Gd3+ ion is monoclinic. The Gd3+ room-temperature spin-Hamiltonian parameters and linewidths were estimated. The phase transition temperatures (Tc) were determined to be 175±1K (first order) in RbPr(SO4)2·4H2O, 178.5±1K (first order) in RbNd(SO4)2·4H2O, 232±0.5K (second order) in RbSm(SO4)2·4H2O, and 230.5±0.5K (second order) in RbEu(SO4)2·4H2O. In RbPr(SO4)2·4H2O and RbNd(SO4)2·4H2O, the occurrence of the first-order phase transitions was deduced from abrupt changes in the behavior of the linewidth, zero-field splitting, and line positions, and coexistence of lines observed below and above Tc. In addition, there were observed occurrences of two more phase transitions second order in nature in RbPr(SO4)2·4H2O (Tc1=261K, Tc2=207.5K) and in RbNd(SO4)2·4H2O (Tc1=250K, Tc2=219.5K); these were not as sharply defined as the preceding ones. Below Tc, for all the crystals, the symmetry of the crystals was found to be lower than monoclinic, the four ions in the unit cell becoming magnetically inequivalent from each other. The observed second-order phase transitions in the four crystals were found to be in agreement with Landau theory of second-order phase transitions; the critical exponent was determined to be β congruent 0.51. copyright 1997 The American Physical Society

  6. A new aqueous activity model for geothermal brines in the system Na-K-Ca-Mg-H-Cl-SO4-H2O from 25 to 300 degrees C

    DEFF Research Database (Denmark)

    Hingerl, Ferdinand F.; Wagner, Thomas; Kulik, Dmitrii A.;

    2014-01-01

    A revised formulation (named REUNIQUAC) of the Extended Universal QUAsiChemical (EUNIQUAC) activity model has been developed, which fits excess thermodynamic properties of binary and selected aqueous ternary electrolyte solutions in the system Na-K-Ca-Mg-H-Cl-SO4-H2O over temperatures from 298 to...

  7. Synthesis and structure of 3D heterometallic (3d-4f) coordination polymers: {[Ln_2Cu(pydc)_4(H_2O)_6]·2H_2O}_n

    Institute of Scientific and Technical Information of China (English)

    MA JingXin; HUANG XiaoFeng; WEI RuiPing; LIU WeiSheng

    2009-01-01

    Two new 3D heterometallic (3d-4f) coordination polymers {[Ln_2Cu(pydc)_4(H_2O)_6]·2H_2O}_n [Ln = Eu (1) and Gd (2)] have been synthesized by hydrothermal reactions and characterized by elemental analysis, X-ray single-crystal analyses, and IR spectroscopy. X-ray crystal structure analyses show that 1 and 2 possess 3D networks and strong intramolecular hydrogen bonding interactions which was confirmed by thermogravimetric (TG) analysis.

  8. Synthesis and crystal structure of aquatetrakis(dimethyl sulfoxide)dioxo-neptunium(6) silicotungstate [NpO2(DMSO)4(H2O)]2(SiW12O4)

    International Nuclear Information System (INIS)

    Monocrystals of [NpO2(DMSO)4(H2O)]2(SiW12O4) are obtained and their structure is interpreted. The structure is composed of complex [NpO2(DMSO)4(H2O)]2+ cations and (SiW12O4)4- heteropolyanions (HPA). Anions and cations are combined by O-O bonds (2.82(3) and 2.67(3) A) in chains. Every molecule of water in [NpO2(DMSO)4(H2O)]2+ cation is a donor of protons for oxygen atoms of two neighbouring HPA. Coordination polyhedron of Np(6) atom is defined as pentagonal bipyramid (CN=7). NpO2 grouping has a close structure to linear and symmetry: O=Np=O angle - 179(1) Deg, Np=O bond lengths are equal 1.73(2) and 1.74(2) A. Equatorial plane of NpO22+ cation is formed by oxygen atoms of four DMSO molecules and one water molecules (Np-Oequ 2.33(1)-2.48(1) A). Tetrahedron SiO44- has two statistically equally probable orientations in HPA (SiW12O40)4+

  9. Synthesis of Mg5(CO3)4(OH)2·4H2O with Flower-like Microstructure and Its Catalytic Activity for Transesterification of Dimethyl Carbonate with Phenol

    Institute of Scientific and Technical Information of China (English)

    WANG Qiang; WANG Ke-li; WU Xing-long; LUO Sheng-jun; HU Chang-wen

    2007-01-01

    A novel flower-like hydrated magnesium carbonate hydroxide, Mg5(CO3)4(OH)2 · 4H2O, with micro-structure composed of individual thin nano-sheets was synthesized using a facile solution route without the use of template or organic surfactant. Reaction time has an important effect on the final morphology of the product. The micro-structure and morphology of Mg5(CO3)4(OH)2·4H2O were characterized by means of X-ray diffractometry ( XRD), fieldemission scanning electron microscopy(FE-SEM). Brunauer-Emmett-Teller(BET) surface areas of the samples were also measured. The probable formation mechanism of flower-like micro-structure was discussed. It was found that Mg5(CO3)4(OH)2·4H2O with flower-like micro-strucure was a novel and efficient catalyst for the synthesis of diphenyl carbonate (DPC) by transesterification of dimethyl carbonate (DMC) with phenol.

  10. 四元体系NaCl-NaBr-Na2SO4-H2O348K相平衡研究%Study on Phase Equilibria for Quaternary System of NaCl-NaBr-Na2SO4-H2O at 348 K

    Institute of Scientific and Technical Information of China (English)

    张勇刚; 桑世华; 张凯杰; 胡富铭; 崔瑞芝

    2013-01-01

    The phase equilibria of the quaternary system of NaCl - NaBr - Na2SO4 - H2O at 348 K are investigated, and the solubility and density of the solution are determined by isothermal e-quilibrium method. The experimental results indicate that the quaternary system is the system with solid in the solution. Based on the experimental data, the phase diagram of the quaternary system is plotted, which consists of a univariant dissolution curve and two crystallization fields: Na ( Cl 、Br) and Na2SO4. The experimental results show that the sodium bromide has the salting - out effect on sodium chloride. Meanwhile, the rule of density is discussed briefly.%采用等温溶解平衡法研究了348 K下四元体系NaCl-NaBr-Na2 SO4-H2O的相平衡规律,测定了平衡液相的溶解度和密度.研究发现,四元体系NaCl-NaBr-Na2SO4-H2O是含有固体溶液的体系.根据实验研究数据绘制了等温溶解度图,相图中只有一条单变量溶解曲线,两个结晶相区,平衡固相分别为Na(Cl、Br)和Na2SO4.实验结果表明,NaBr对NaCl具有盐析效应,并简要讨论了密度变化规律.

  11. Crystal structure, magnetic, thermal behavior, and spectroscopic studies of two new bimetallic hydrogenselenites: [Cu2-xNix (HSeO3)2Cl2.4H2O], (x = 0.62; 0.91)

    Science.gov (United States)

    Hentech, I.; Zehani, K.; Kabadou, A.; Ben Salah, A.; Loukil, M.; Bessais, L.

    2016-08-01

    Two new iso-structural bimetallic hydrogenselenites [Cu2-xNix(HSeO3)2Cl2.4H2O] (x = 0.62; 0.91) have been synthesized from solution and characterized by single-crystal and powder X-ray diffraction. They crystallized in the orthorhombic Pnma space group with the following lattice parameters: for Cu1.09Ni0.91(HSeO3)2Cl2.4H2O: a = 9.0931 (2) Å, b = 17.7717 (4) Å, c = 7.1620 (2) Å, Z = 4, and for Cu1.38Ni0.62(HSeO3)2Cl2.4H2O: a = 9.0931 (4) Å, b = 17.7467 (7) Å, c = 7.1717 (3) Å; Z = 4. The crystal structure of this compound consists by a three-dimensional framework, but it may be described as a bi-dimensional structure consisting of layers, parallel to the (010) plane formed by two types of (Cu/Ni) octahedral and (HSeO3)- trigonal pyramids. The magnetic measurement, thermal and spectroscopic studies were performed for these compounds. The magnetic results reveal the appearance of a weak ferromagnetic behavior at low temperature (Tc = 16 K for x = 0.91 and 18.8 K for x = 0.62). The DSC analysis enabled us to locate two endothermic peaks. The first peak can be attributed to a completely dehydration of the material, in this transformation, the compounds undergo a structural phase transition which can favor a non-centrosymmetric phase at high temperature confirmed by the thermodiffractograms measurement. The second peak for these samples is due to the ferro-paraelectric phase transition which can be explained by an order- disorder transition.

  12. Comparative calculation of EPR spectral parameters in [MoVOX4]−, [MoVOX5]2−, and [MoVOX4(H2O)]− complexes†

    OpenAIRE

    Hadt, Ryan G.; Nemykin, Victor N.; Olsen, Joseph G.; Basu, Partha

    2009-01-01

    The EPR spectral parameters, i.e. g-tensors and molybdenum hyperfine couplings, for several d1 systems of the general formula [MoVEX4]n−, [MoVOX5]2−, and [MoVOX4(H2O)]− (E = O, N; X = F, Cl, Br; n = 1 or 2) were calculated using Density Functional Theory. The influence of basis sets, their contraction scheme, the type of exchange-correlation functional, the amount of Hartree-Fock exchange, molecular geometry, and relativistic effects on the calculated EPR spectra parameters have been discusse...

  13. Untersuchungen zu den Phasengleichgewichten der Systeme (CO2 + MDEA + PIPH2 + H2O), (CH4 + organische Lösungsmittel) und das LW-H-V-Gleichgewicht des Systems (CH4 + H2O)

    OpenAIRE

    Böttger, Arne

    2009-01-01

    In der vorliegenden Arbeit werden experimentelle und theoretische Untersuchungen für die Löslichkeiten von Methan in den organischen Lösungsmitteln Petroleumbenzin, 1-Oktanol, n-Hexan und n-Dodekan sowie Untersuchungen des LW-H-V-Gleichgewichts des Systems (CH4 + H2O) vorgestellt. Im Vergleich zu den Vorhersageergebnissen von Sloan sowie Parrish und Praus-nitz wurde mit dem in der vorliegenden Arbeit weiterentwickelten, thermodynamischen Modell für das Hydratgleichgewicht des Systems (CH4 + H...

  14. The IAGOS GHG package: a measurement system for continuous airborne observations of CO2, CH4, H2O and CO

    Science.gov (United States)

    Gerbig, C.; Filges, A.; Franke, H.; Klaus, C.; Chen, H.

    2012-12-01

    ensures a safe operation. During maintenance, calibration gases are analysed and replenished, and a functional inspection, followed by replacement of depleted or damaged parts, will be undertaken. Spare instrumentation will be used to provide for year-round GHG measurements on board each aircraft. We present results from recent test flights and laboratory tests that document the performance for GHG and water vapor measurements. Furthermore, future applications of the IAGOS-GHG data stream, provided in near-real-time via SatCom to the weather prediction centres, will be discussed, including the improved estimation of GHG budgets at regional to continental scales, the assessment of vertical transport in atmospheric models through comparison with observed vertical tracer distributions, and the validation of remote sensing measurements of GHGs.

  15. The Preparation of Pigment of Iron Black Oxide from the Byproduct of Titanium DioxideFeSO4.H2O%钛白副产硫酸亚铁制备氧化铁黑的研究

    Institute of Scientific and Technical Information of China (English)

    周宏民; 刘跃进; 熊双喜

    2001-01-01

    During the production of titanium pigment, there is a large amount of byproductFeSO4* H2O which contains some impurities, such as Ti, Mn etc. A new technology of preparing iron black oxide from the ferrous sulfate septihydrate was proposed in this paper. The method consists of steps: first purifying the by product FeSO4* H2O, then adding ammonia to form ferrous hydroxide and finally oxidizing ferrous hydroxide into iron black oxide by air under the given conditions. Comparing with the traditional technology, both lower product cost and less waste byproduct were obtained by the method. Some factors affecting the preparing of iron black oxide were tested and the optimal conditions of oxidizing reaction were obtained.%钛白生产中副产大量硫酸亚铁,且含有Ti、Mn等杂质.先将副产硫酸亚铁经净化处理,然后用氨水和空气进行反应生产氧化铁黑,产品质量达到国家标准.与传统工艺相比,生成成本低,减少了三废的排放.对合成氧化铁黑的影响因素也进行了试验研究,得出了较好的合成工艺条件.

  16. Deposition of ZnSO4 · 3Zn(OH2 · 4H2O films by SILAR method and their study by XRD, SEM and µ-Raman Depósito de películas de ZnSO4 • 3Zn(OH2 • 4H2O por el método SILAR y su estudio por DRX, SEM Y μ-RAMAN

    Directory of Open Access Journals (Sweden)

    F N Jiménez García

    2012-06-01

    Full Text Available ZnSO4 · 3Zn(OH2 · 4H2O(Zinc Sulfate Hidroxide Hidrate films were obtained on glass substrates by SILAR method. It was employed a precursorsolution of ZnSO4 and MnSO4 and water near boiling point complexed with 1 ml of NH4OH as a second solution. Films were treated on air at 300oC by 1 hour. Both films ZnSO4·3Zn(OH2·4H2O as ZnO are important protective against zinc corrosion because they are passive films that give a longer duration to material, it is therefore relevant to study their response to temperature changes. For those reasons films were analyzed before and after thermal treatment to study the structural and morphological changes by X ray diffraction (XRD, Scanning electron microscopy (SEM and Raman Microscopy techniques. It was found before thermal treatment by XRD thepresence of ZnSO4 · 3Zn(OH2 · 4H2O triclinic phase and after such treatment the ZnO hexagonal phase was evidenced. The morphology identified by SEM before thermal treatment was sheets formed by platelet like structure of micrometric size which changes after thermal treatment to a combination ofthose sheets with flowers like structure characteristic of ZnO hexagonal. By µ-Raman the hexagonal ZnO phase before thermal treatment as the triclinicZnSO4 · 3Zn(OH2 · 4H2O phase after thermal treatment were confirmed.One objective of this study was to obtain this protective corrosion material in a controlled manner by techiniques of low cost and high simplicity as Silarmethod. Which, even under temperture increases continue being protective corrosion although suffers phase changes because new phases have protectivecorrosive characteristics too.Se obtuvieron películas de ZnSO4 · 3Zn(OH2 · 4H2O (Zinc Sulfate Hidroxide Hidrate sobre sustratos de vidrio mediante procedimiento SILAR. Se empleó una solución precursora de ZnSO4 y MnSO4 y una segunda solución de agua a ebullición acomplejada con 1 ml de NH4OH. Se realizó tratamiento térmico en aire a 300oC por

  17. Magnetic Properties of a Three-dimensional Supramolecular Complex[Co(hmt)2(SCN)2(H2O)2][Co(SCN)2(H2O)4](H2O)2%三维超分子配合物[Co(hmt)2(SCN)2(H2O)2][Co(SCN)2(H2O)4](H2O)2的磁性质(英文)

    Institute of Scientific and Technical Information of China (English)

    李纲; 李金鹏; 王翠红; 李林科; 侯红卫

    2002-01-01

    Supramolecular complex [Co(hmt)2(SCN)2(H2O)2][Co(SCN)2(H2O)4](H2O)2 (hmt =hexamethylenetetramine) is prepared according to previous literature. The determination of variable-temperature magnetic susceptibilities (5~300 K) shows that the magnetic behavior obeys the Curie-Weiss law over the whole temperature range. In this compound weak antiferromagnetic coupling can be observed.%参照文献制备了三维超分子配合物[Co(hmt)2(SCN)2(H2O)2][Co(SCN)2(H2O)4](H2O)2, 测试了该化合物在5~300 K范围内的变温磁化率.结果表明,其磁行为在测定的温度范围内遵守Curie-Weiss定律, 金属离子之间存在弱的反铁磁偶合.

  18. Face-Centred-Cubic Artificial Opal Embedded with CdS Quantum Dots

    Institute of Scientific and Technical Information of China (English)

    徐岭; 李明海; 张宇; 马懿; 徐骏; 黄信凡; 陈坤基

    2002-01-01

    Highly monodispersed colloidal silica spheres in sub-micrometre size with distribution standard deviation less than 5% were synthesized by a chemical method. Using the self-crystallization of the silica spheres, we successfully obtained the three-dimensional close-packed face-centred-cubic silica matrices and artificial opals. Then,a colloidal photonic crystal embedded with CdS quantum dots (QDs) was also chemically prepared by using artificial opals as a template. A reflection spectra study reveals that both artificial opals with and without CdS QDs possess (111) directional photonic bandgap features.

  19. Anorthominasragrite, V4+O (SO4) (H2O)5, a new mineral species from Temple Mountain, Emery County, Utah, U.S.A.: description, crystal structure and hydrogen bonding

    International Nuclear Information System (INIS)

    Anorthominasragrite, V4+ O(SO4) (H2O)5, is a new mineral species from Temple Mountain, Emery County, Utah, U.S.A. It occurs as blue-green crusts and spherical granular aggregates (up to ∼1 mm across) in a fossil (Triassic) tree; individual crystals are 3. Anorthominasragrite is biaxial positive, with α 1.548, β 1.555, γ 1.574, all ±0.002, 2V(obs.) = 86(1)o, 2V(calc.) =63o, non-pleochroic, XΛ c ∼ 18o (in β obtuse), Y ∼ a, Z Λ b ∼ 19o (in γ obtuse). Anorthominasragrite is triclinic, space group P1, α 7.548(3), b 7.805(2), c 7.821(3) Angstroem, α 79.03(4), β71.94(3), γ 65.31(3)o, V397.1(2) Angstroem3, Z=2. The strongest seven lines in the X-ray powder-diffraction pattern [d in Angstroem(I)(hkl)] are: 6.617(100)(100), 7.053(80)(010), 4.116(80)(110), 3.712(80)(121,002,211), 3.206(70)(221), 2.934(50)(112,102), 5.314(30)(011). Chemical analysis with an electron microprobe gave VO2 33.93, SO3 30.78, H2O (calc.) 35.52, sum 100.23 wt.%; the amount of H2O was determined by crystal-structure analysis. The resulting empirical formula on the basis of 10 anions (including 5 H2O) is V1.04 S0.98 O5(H2O)5; the end-member formula is V O (SO4) (H2O)5. Anorthominasragrite is the triclinic polymorph of V O (SO4) (H2O)5. The crystal structure of anorthominasragrite was solved by direct methods and refined to an R index of 3.2% for 673 observed (F indexO > 5 σF) reflections measured with an automated four-circle X-ray diffractometer using MoKα X-radiation. There is one V site occupied by V4+ and surrounded by three O atoms and three (H2O) groups in an octahedral arrangement, with one short vanadyl bond (1 .587 Angstroem), four similar equatorial bonds (), and one longer V-O bond (2.253 Angstroem) trans to the vanadyl bond. The structure consists of (V4+φ6) (φ:unspecified anion) octahedra and (SO4) tetrahedra that corner-share O2- vertices to form (V4+O)2 (H2O)6 (SO4)2 groups [as in bobjonesite, V4+ O(SO4) (H2O)3], with two additional isolated (H2O) groups. (author)

  20. Synthesis and crystal structure of a new uranium complex [Usub(IV)(SCN)4, 4H2O]1 [18-crown-6]sub(1,5), 3H2O, 1 methyl isobutyl ketone

    International Nuclear Information System (INIS)

    The synthesis and crystal structure of the title compound are reported. This uranium complex crystallizes in the P bar 1 triclinic space group with: a = 10.63A; b = 14.60A; c = 15.95A; α = 75030; β = 88040; γ =82.20. The structure was solved by Patterson and successive Fourier difference syntheses methods to a final R value: 0.047. The uranium atom is eight-coordinated to four N-C-S groups and four oxygen atoms from water molecules, in a distorted square antiprism polyhedron. The crown-ether molecules have not the same configuration as uncomplexed ether molecules. They are connected to neutral [U(SCN)4, 4H2O] units by hydrogen bonding via water molecules. The cohesion of the structure is given by hydrogen bonds. (author)

  1. Saccharinato complexes of Ce(V) with 2-hydroxypyridine: Synthesis, spectroscopic and thermal characteristics of [Ce(sac) 2(SO 4)(H 2O) 4] and [Ce(sac) 2(SO 4)(PyOH) 2

    Science.gov (United States)

    Gaballa, Akmal S.; Teleb, Said M.; Müller, Thomas

    2008-10-01

    The synthesis of Ce(IV) complexes [Ce(sac) 2(SO 4)(H 2O) 4] ( 1) and [Ce(sac) 2 (SO 4)(PyOH) 2] ( 2) (sac = saccharinate, PyOH = 2-hydroxypyridine) starting with sodium saccharinate is described. Their vibrational and nuclear magnetic resonance ( 1H, 13C) spectra as well as their thermal mode of degradation were investigated. The data indicate that sac in complex 1 behaves as a monodentate ligand through the nitrogen atoms. Saccharinato ligand in complex 2 shows different mode of coordination, where it behaves as tridentate and binds Ce(IV) through its carbonylic oxygen, nitrogen and sulphonylic oxygen atoms. The most probable structure in complex 2 is that, units of [Ce(sac) 2(SO 4)(PyOH) 2] are linked by bridges of the O- of sac sulphonyl leading to polymeric chains.

  2. Structure and magnetic properties of a new single-molecule magnet [Mn11Fe1O12 (CH3COO)16(H2O)4] ·2CH3COOH·4H2O

    Institute of Scientific and Technical Information of China (English)

    Cao Hui-Bo; He Lun-Hua; Wang Fang-Wei

    2005-01-01

    A new single-molecule magnet [Mn11Fe1O12(CH3COO)16(H2O)4].2CH3COOH.4H2O (Mn11Fe1) has been synthesized. The structure has been studied by the single crystal x-ray diffraction. The difference of Jahn-Teller distortion between Fe3+ and Mn3+ ion reveals that Fe3+ ion substitutes for Mn3+ ion on the Mn(3) sites in the Mn12 skeleton.The temperature dependence of the magnetization gives a blocking temperature TB=1.9K for Mn11Fe1. Based on the magnetization process analysis of the crystal at T=2K, we suggest that Mn11Fe1 has the ground state with a total spin S= 11/2.

  3. Crystal Structure and Characterization of a New Mixed-valence Manganese(Ⅲ/Ⅳ) Complex: [Mn2(cyclen)2(μ-O)2](ClO4)3-4H2O

    Institute of Scientific and Technical Information of China (English)

    任颜卫; 李珺; 张逢星; 张金花; 郭惠

    2005-01-01

    The mixed-valence manganese(Ⅲ/Ⅳ) complex [Mn2(cyclen)2(μ-O)2](ClO4)3-4H2O (1) (cyclen=1,4,7,10-tetraazacyclododecan) with chemical formula C16H48Cl3Mn2N8O18 has been synthesized and characterized by single crystal X-ray diffraction analysis, elemental analysis, IR and electronic spectra. The results showed that the manganese(Ⅲ/Ⅳ) ions were six-coordinated by four nitrogen atoms from cyclen and two oxygen atoms from the oxygen bridge, forming a distorted octahedron geometry. There were two very strong peaks in the range of 400-700 nm in electronic spectrum, which was similar to Mn catalase and Mn ribonucleotide reductase extracted from organisms.Electrochemical study indicated that the complex underwent a quasi-reversible one-electron reduction and oxidation at E1/2=0.827 V in acetonitrile.

  4. Thermodynamic Properties of Magnesium Chloride Hydroxide Hydrate (Mg3Cl(OH)5:4H2O, Phase 5), and Its importance to Nuclear Waste Isolation in Geological Repositories in Salt Formations

    Science.gov (United States)

    Xiong, Y.; Deng, H.; Nemer, M. B.; Johnsen, S.

    2009-12-01

    MgO (bulk, pure MgO corresponding to the mineral periclase) is the only engineered barrier certified by the Environmental Protection Agency for emplacement in the Waste Isolation Pilot Plant (WIPP) in the US, and an Mg(OH)2-based engineered barrier (bulk, pure Mg(OH)2 corresponding to brucite) is to be employed in the Asse repository in Germany. Both the WIPP and the Asse are located in salt formations. The WIPP is a U.S. Department of Energy geological repository being used for the permanent disposal of defense-related transuranic waste (TRU waste). The repository is 655 m below the surface, and is situated in the Salado Formation, a Permian salt bed mainly composed of halite, and of lesser amounts of polyhalite, anhydrite, gypsum, magnesite, clays and quartz. The WIPP Generic Weep Brine (GWB), a Na-Mg-Cl dominated brine, is associated with the Salado Formation. The previous vendor for MgO for the WIPP was Premier Chemicals and the current vendor is Martin Marietta Materials. Experimental studies of both Premier MgO and Martin Marietta MgO with the GWB at SNL indicate the formation of magnesium chloride hydroxide hydrate, Mg3Cl(OH)5:4H2O, termed as phase 5. However, this important phase is lacking in the existing thermodynamic database. In this study, the solubility constant of phase 5 is determined from a series of solubility experiments in MgCl2-NaCl solutions. The solubility constant at 25 oC for the following reaction, Mg3Cl(OH)5:4H2O + 5H+ = 3Mg2+ + 9H2O(l) + Cl- is recommended as 43.21±0.33 (2σ) based on the Specific Interaction Theory (SIT) model for extrapolation to infinite dilution. The log K obtained via the Pitzer equations is identical to the above value within the quoted uncertainty. The Gibbs free energy and enthalpy of formation for phase 5 at 25 oC are derived as -3384±2 (2σ) kJ mol-1 and -3896±6 (2σ) kJ mol-1, respectively. The standard entropy and heat capacity of phase 5 at 25 oC are estimated as 393±20 J mol-1 K-1 and 374±19 J mol-1 K

  5. Microcalorimetric study about biological effect of a synthetic complex: La(Glu)(Im)6(ClO4)3.4HClO4.4H2O

    International Nuclear Information System (INIS)

    A complex of lanthanum perchloric acid coordinated with glutamic acid, La(Glu)(Im)6(ClO4)3.4HClO4.4H2O was synthesized and characterized. The biological effect of the complex was evaluated by microcalorimetry on the growth of E. coli DH5α. Power-time curves of the growth metabolism of E. coli DH5α were studied using a TAM Air Isothermal Microcalorimeter at 37 oC. From the power-time curves, the parameters such as growth rate constants (k), inhibitory ratio (I), the maximum heat power (Pm) and the time of the maximum heat power (tm) were obtained. The results show that the concentrations of the complex affect obviously the growth metabolism of E. coli DH5α. The stimulatory effect on growth of E. coli DH5α was observed when the concentration of the complex was kept in the range of (0-0.5 μg mL-1). In contrast to the lower concentration, in the case of higher concentration of the complex (0.5-5.0 μg mL-1), an inhibitory effect occurred.

  6. Synthesis and Structural Characterization of a Novel Coordination Polymer [Cd(C4H2O4)(C3H4N2)3]n·2nH2O

    Institute of Scientific and Technical Information of China (English)

    YUE Lin; ZHOU Qiu-Xiang; WANG Yan-Ji; ZHAO Xin-Qiang

    2005-01-01

    At room temperature, a new three-dimensional organic-inorganic coordination polymer [Cd(C4H2O4)(C3H4N2)3]n·2nH2O was synthesized by the reaction of Cd(CH3COO)2(2H2O, imidazole and fumaric acid. It was characterized by EA, IR, TG-DTA and X-ray single-crystal diffraction. It crystallizes in the monoclinic system, space group P21/n with a = 8.980(3), b = 15.803(5), c = 13.415(4) (A), α = γ = 90.00°, β = 98.450(5)°, F(000) = 936, Mr = 466.73, Z = 4, V = 1883.0(10) (A)3, Dc = 1.646 g/cm3, μ(MoKα) = 1.201 mm-1, S = 1.041, the final R = 0.0237 and wR = 0.0469. The crystal structure shows that the cadmium has a distorted octahedral environment with three carboxyl oxygen donors and three imidazole nitrogen donors. Each cadmium atom is linked by a fumatate as bridging ligand to afford a one-dimensional framework, and then an infinite threedimensional supramolecular network is formed through hydrogen bonding interactions.

  7. Development of a chemical model for Hanford tank wastes: Na+-NO3--NO2--SO42--CO32--F--PO43--OH--Al(OH)4-H2O system

    International Nuclear Information System (INIS)

    Radioactive wastes stored in underground tanks at the U.S. Department of Energy's Hanford Site are already in contact or potentially can contact solutions that contain high concentrations of the following electrolyte components: NaNO3, NaNO2, NaOH, NaF, NaAl(OH)4, Na2SO4, Na3PO4 and Na2CO3. Understanding the equilibrium chemistry of these complex chemical systems is one part of developing effective waste pretreatment and sludge dissolution processes. To gain this understanding the authors have derived solubility and osmotic data experimentally for the chemical system Na+-NO3--NO2--SO42--CO32--F--PO43--OH--Al(OH)4--H2O in the temperature range 25 degrees C to 100 degrees C. The interpretation/prediction of these experimental data, as well as other data in the literature, using the Pitzer ion-interaction model are presented. In addition, comparisons with chemical systems more complex than those used for model parameterization are presented to verify the modeling approach. Ongoing experimental studies and model development for other important sludge components such as Al, Si, and Cr are also discussed

  8. Synthesis, Properties and Crystal Structure of a New Bismuth Oxalate:Na(C5NH6)[Bi(H2O)(C2O4)2]2·4H2O

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    A new bismuth oxalate Na(C5NH6)[Bi(H2O)(C2O4)2]2.4H2O has been obtained under hydrothermal conditions and characterized by X-ray diffraction.It crystallizes in mono-clinic, space group C2/m with a = 12.020(5), b = 11.190(8), c = 11.067(10)(A), β= 121.78(2)°,NaBi2CI3NH18O22, Mr= 981.24, V = 1265.4(16)(A)3, Z = 2, Dc = 2.575 g/cm3, μ(MoKα) = 14.005 mm-1, F(000) = 912, R = 0.0179 and wR = 0.0394.In the structure, the Bi(Ⅲ) centers are interconnected by oxalate ligands to produce honeycomb-like layers, which are further pillared by bridging ligand oxalate molecules to form a 3-D open-framework structure.Furthermore, the title compound exhibits blue luminescence with the emission peaks located at 394nm in the solid state at room temperature, and thus it could be useful in the field of photoactive materials.

  9. Synthesis, crystal structure, thermal analysis and vibrational spectroscopy accomplished with DFT calculation of new hybrid compound [2-CH3C6H4NH3]HSO4.H2O

    Science.gov (United States)

    Ben Hassen, C.; Boujelbene, M.; Marweni, S.; Bahri, M.; Mhiri, T.

    2015-10-01

    The present paper undertakes the study of a new organic/inorganic hybrid compound [2-CH3C6H4NH3]HSO4.H2O characterized by the X-ray diffraction, TG-DTA, IR and Raman spectroscopy accomplished with DFT calculation. It is crystallized in the monoclinic system with the centrosymmetric space group P 21/c, with a = 9.445 (5) Å, b = 10.499 Å, c = 10.073 Å, β = 90.627 (5)° and Z = 4. The atomic arrangement can be described as inorganic layers built by infinite chains, parallel to the (a c) planes between which the organic cations are inserted. In this atomic arrangement, hydrogen bonds and π-π interactions between the different species have an important role in the tri-dimensional network cohesion. Besides, the X-ray powder diffraction of the title compound confirms the existence of only one phase at room temperature. The thermal decomposition of precursors studied by thermo gravimetric analysis (TGA), the differential thermal analysis (DTA) and the temperature-dependent X-ray diffraction, show crystalline anhydrous compounds upon dehydration. DFT/BHHLYP calculations were performed, using the DZV (d,p) basis set, to determine the harmonic frequencies of the vibrational modes of an optimized cluster structure. The calculated modes were animated using the Molden graphical package to give tentative assignments of the observed IR and Raman spectra.

  10. Structural refinement of Nd[Fe(CN) 6]·4H 2O and study of NdFeO 3 obtained by its oxidative thermal decomposition at very low temperatures

    Science.gov (United States)

    Navarro, M. Carolina; Pannunzio-Miner, Elisa V.; Pagola, Silvina; Gómez, M. Inés; Carbonio, Raúl E.

    2005-03-01

    The crystal structure of Nd[Fe(CN) 6]·4H 2O has been refined by Rietveld analysis using high resolution synchrotron powder X-ray diffraction data. It belonged to the orthorhombic crystal system, Cmcm space group, with cell parameters: a=7.473952(1) Å, b=12.919104(2) Å and c=13.800549(2) Å. The change in space group from P6 3/ m which is observed in the pentahydrates (LnFe(CN) 6·5H 2O) to Cmcm in the tetrahydrates has been analyzed to be a consequence of the change in 9-fold coordination of Nd 3+ in the pentahydrates to 8-fold coordination in the tetrahydrates, which changes the Nd 3+ environment from tricapped trigonal prism to a distorted tricapped trigonal prism or square antiprism. Its decomposition process in air to produce NdFeO 3 has been followed by thermogravimetric and differential thermal analysis, IR spectroscopy and laboratory powder XRD. We found that it is possible to synthesize crystalline NdFeO 3 at temperatures as low as 380 °C and refine the structure of single phase crystalline NdFeO 3 synthesized by this method at 600 °C.

  11. Structural refinement of Nd[Fe(CN)6].4H2O and study of NdFeO3 obtained by its oxidative thermal decomposition at very low temperatures

    International Nuclear Information System (INIS)

    The crystal structure of Nd[Fe(CN)6].4H2O has been refined by Rietveld analysis using high resolution synchrotron powder X-ray diffraction data. It belonged to the orthorhombic crystal system, Cmcm space group, with cell parameters: a=7.473952(1)A, b=12.919104(2)A and c=13.800549(2)A. The change in space group from P63/m which is observed in the pentahydrates (LnFe(CN)6.5H2O) to Cmcm in the tetrahydrates has been analyzed to be a consequence of the change in 9-fold coordination of Nd3+ in the pentahydrates to 8-fold coordination in the tetrahydrates, which changes the Nd3+ environment from tricapped trigonal prism to a distorted tricapped trigonal prism or square antiprism. Its decomposition process in air to produce NdFeO3 has been followed by thermogravimetric and differential thermal analysis, IR spectroscopy and laboratory powder XRD. We found that it is possible to synthesize crystalline NdFeO3 at temperatures as low as 380oC and refine the structure of single phase crystalline NdFeO3 synthesized by this method at 600 deg. C

  12. Synthesis, Properties and Crystal Structure of a Novel Coordinated Polymer: {(H2en)(H3O)[(BiPb(C2O4)4(H2O)2)]·2(H2O)}n

    Institute of Scientific and Technical Information of China (English)

    GUO Wen-Jun; ZHANG Han-Hui; HUANG Chang-Cang; SUN Rui-Qing; CHEN Yi-Ping; CAO Yan-Ning

    2005-01-01

    A novel oxalate compound {(H2en)(H3O)[BiPb(C2O4)4(H2O)2]·2(H2O)}n 1 (en = ethylenediamine) containing lead and bismuth has been synthesized by hydrothermal methods, and structurally characterized by X-ray single-crystal diffraction. It crystallizes in monoclinic, space group P21/c with a = 11.6160(1), b = 12.7426(1), c = 15.5683(5) (A), β = 108.442(4)°, BiPbC10N2O21H21, Mr = 921.46, V = 2186.0(4) (A)3, Z = 4, Dc = 2.800 g/cm3, F(000) = 1712 and μ(MoKα) = 15.837 mm-1. The final R = 0.0502 and wR = 0.1261 for 3391 observed reflections with I > 2(σI). The title com- pound consists of 2-D polyanions and protonized organic amine cations, and they are combined to each other by static attractive force and H-bonds to form the so-called organic-inorganic hybrid material.

  13. Thermodinamically stable phases in the CaO-SiO2-Al2O3-CaSO4-H2O closed system at 25 ºC. Application to cementitious systems

    Directory of Open Access Journals (Sweden)

    Blanco-Varela, M. T.

    2009-06-01

    Full Text Available One of the chief causes of cement and concrete deterioration is the loss of durability prompted by sulphate attack. The existing standards call for long test periods (2- 12 months. Thermodynamic modelling is a particularly appropriate technique for studying systems that only reach equilibrium in the long term. Used in the present study to establish the fields of thermodynamic stability for the phases in the CaO-SiO2-Al2O3-CaSO4-H2O system at 25 ºC. According to the model, gypsum is stable at sulphate ion concentrations of 1.23e-2 mol/kg and over, while ettringite exhibits stability at concentrations ranging from 7.64e-6 to 1.54e-2 mol/kg. Ettringite is compatible with all system phases except SH and gypsum only with ettringite, the C-S-H gels, AH3 and SH. None of the calcium aluminates or silicoaluminates in the system is compatible with gypsum: in its presence, they all decompose to cement deteriorating ettringite. Finally, the model revealed that the maximum sulphate concentration at which C-S-H gel is stable is slightly higher in systems with than without Al2O3.Uno de los principales problemas asociados al deterioro de cementos y hormigones es la pérdida de durabilidad por ataque de sulfatos. La normativa existente requiere largos tiempos de ensayo (2-12 meses. La modelización termodinámica es una técnica particularmente adecuada para el estudio de sistemas que alcanzan el equilibrio en tiempos largos. Aplicando esta metodología se han establecido los campos de estabilidad termodinámica de las fases del sistema CaO-SiO2-Al2O3-CaSO4-H2O a 25 ºC. El yeso es estable a partir de la [SO42-] = 1,23e-2 mol/kg, y la ettringita es estable en un rango de [SO42-] = 7,64e-6 -1,54e-2 mol/kg. La ettringita es compatible con todas las fases del sistema excepto con SH y el yeso sólo con la ettringita, los geles C-S-H, el AH3 y el SH. Ninguno de los aluminatos o silicoaluminatos cálcicos son compatibles con el yeso, en su presencia se descomponen

  14. Differentiating homogeneous and heterogeneous water oxidation catalysis: confirmation that [Co4(H2O)2(α-PW9O34)2]10- is a molecular water oxidation catalyst.

    Science.gov (United States)

    Vickers, James W; Lv, Hongjin; Sumliner, Jordan M; Zhu, Guibo; Luo, Zhen; Musaev, Djamaladdin G; Geletii, Yurii V; Hill, Craig L

    2013-09-25

    Distinguishing between homogeneous and heterogeneous catalysis is not straightforward. In the case of the water oxidation catalyst (WOC) [Co4(H2O)2(PW9O34)2](10-) (Co4POM), initial reports of an efficient, molecular catalyst have been challenged by studies suggesting that formation of cobalt oxide (CoOx) or other byproducts are responsible for the catalytic activity. Thus, we describe a series of experiments for thorough examination of active species under catalytic conditions and apply them to Co4POM. These provide strong evidence that under the conditions initially reported for water oxidation using Co4POM (Yin et al. Science, 2010, 328, 342), this POM anion functions as a molecular catalyst, not a precursor for CoOx. Specifically, we quantify the amount of Co(2+)(aq) released from Co4POM by two methods (cathodic adsorptive stripping voltammetry and inductively coupled plasma mass spectrometry) and show that this amount of cobalt, whatever speciation state it may exist in, cannot account for the observed water oxidation. We document that catalytic O2 evolution by Co4POM, Co(2+)(aq), and CoOx have different dependences on buffers, pH, and WOC concentration. Extraction of Co4POM, but not Co(2+)(aq) or CoOx into toluene from water, and other experiments further confirm that Co4POM is the dominant WOC. Recent studies showing that Co4POM decomposes to a CoOx WOC under electrochemical bias (Stracke and Finke, J. Am. Chem. Soc., 2011, 133, 14872), or displays an increased ability to reduce [Ru(bpy)3](3+) upon aging (Scandola, et al., Chem. Commun., 2012, 48, 8808) help complete the picture of Co4POM behavior under various conditions but do not affect our central conclusions.

  15. Self-Assembly,Crystal Structure and Magnetic Properties of Three-Dimensional Supramolecular Complex [Ni (hmt)2 (SCN)2 (H2O)2 ] [Ni (SCN)2 (H2O)4 ] (H2O)2 (hmt = hexamethylenetetramine)%三维超分子[Ni(hmt)2(SCN)2(H2O)2][Ni(SCN)2(H2O)4](H2O)2的自组装,晶体结构及磁性质(hmt=六次甲基四胺)

    Institute of Scientific and Technical Information of China (English)

    李纲; 朱玉; 李林科; 侯红卫; 樊耀亭; 杜晨霞

    2002-01-01

    Compound [Ni(hmt) 2(SCN) 2(H2O) 2] [Ni(SCN) 2(H2O) 4] (H2O) 2 (hmt = hexamethylenetetramine) was prepared and structurally characterized by means of X-ray single crystal diffraction.The two neutral units [Ni(hmt)2variable-temperature magnetic susceptibilities (5 ~ 300K) shows that the magnetic behavior obeys the Curie-Weiss law over the whole temperature ranges.

  16. Deuteron and triton production in Pb+Pb collisions at 158 A centre dot GeV.

    CERN Document Server

    Hansen, A G; Bøggild, H; Boissevain, J G; Conin, L; Christiansen, P; Dodd, J; Erazmus, B; Esumi, S; Fabjan, Christian Wolfgang; Ferenc, D; Fields, D E; Franz, A; Gaardhøje, J J; Hansen, A G; Hansen, O; Hardtke, D; Hecke, H V; Holzer, E B; Humanic, T J; Hummel, P; Jacak, B V; Jayanti, R; Kaimi, K; Kaneta, M; Kohama, T; Kopytine, M; Leltchouk, M; Ljubicic, A; Lörstad, B; Martin, L; Maeda, N; Malina, R; Medvedev, A; Murray, M; Ohnishi, H; Paic, G; Pandey, S U; Piuz, François; Pluta, J; Polychronakos, V; Potekhin, M V; Poulard, G; Reichhold, D M; Sakaguchi, A; Simon-Gillo, J; Schmidt-Sørensen, J; Sondheim, W E; Sugitate, T; Sullivan, J P; Sumi, Y; Willis, W J; Wolf, K L; Xu, N; Zachary, D S

    1999-01-01

    NA44 has measured the invariant cross section of deuterons and tritons at non zero p sub t in 158 A centre dot GeV lead on lead collisions at CERN SPS. Normalized transverse mass spectra and coalescence parameters versus p sub t have been calculated showing a significant transverse flow. Radius parameters have been extracted using a simple thermal coalescence model. Results from RQMD+coalescence calculations are compared to the data.

  17. Nature of magnetic interactions in 3D {[M(II)(pyrazole)4]2[Nb(IV)(CN)8].4H2O}n (M = Mn, Fe, Co, Ni) molecular magnets.

    Science.gov (United States)

    Pinkowicz, Dawid; Pełka, Robert; Drath, Olga; Nitek, Wojciech; Bałanda, Maria; Majcher, Anna Małgorzata; Poneti, Giordano; Sieklucka, Barbara

    2010-08-16

    The self-assembly of [Nb(IV)(CN)(8)](4-) with different 3d metal centers in an aqueous solution and an excess of pyrazole resulted in the formation of four 3D isostructural compounds {[M(II)(pyrazole)(4)](2)[Nb(IV)(CN)(8)].4H(2)O}(n), where M(II) = Mn, Fe, Co, and Ni for 1-4, respectively. All four assemblies crystallize in the same I4(1)/a space group and show identical cyanido-bridged structures decorated with pyrazole molecules coordinated to M(II) centers. All four compounds show also long-range magnetic ordering below 24, 8, 6, and 13 K, respectively. A thorough analysis of the structural and magnetic data utilizing the molecular field model has allowed for an estimation of the values of coupling constants J(M-Nb) attributed to the one type of M(II)-NC-Nb(IV) linkage existing in 1-4. The J(M-Nb) values increase monotonically from -6.8 for 1 through -3.1 for 2 and +3.5 for 3, to +8.1 cm(-1) for 4 and are strongly correlated with the number of unpaired electrons on the M(II) metal center. Average orbital contributions to the total exchange coupling constants J(M-Nb) have also been identified and calculated: antiferromagnetic J(AF) = -21.6 cm(-1) originating from the d(xy), d(xz), and d(yz) orbitals of M(II) and ferromagnetic J(F) = +15.4 cm(-1) originating from d(z(2)) and d(x(2)-y(2)) orbitals of M(II). Antiferromagnetic interaction is successively weakened in the 1-4 row with each additional electron on the t(2g) level, which results in a change of the sign of J(M-Nb) and the nature of long-range magnetic ordering from ferrimagnetic in 1 and 2 to ferromagnetic in 3 and 4. PMID:20690767

  18. Nanodiamond-based nanostructures for coupling nitrogen-vacancy centres to metal nanoparticles and semiconductor quantum dots

    Science.gov (United States)

    Gong, Jianxiao; Steinsultz, Nat; Ouyang, Min

    2016-01-01

    The ability to control the interaction between nitrogen-vacancy centres in diamond and photonic and/or broadband plasmonic nanostructures is crucial for the development of solid-state quantum devices with optimum performance. However, existing methods typically employ top-down fabrication, which restrict scalable and feasible manipulation of nitrogen-vacancy centres. Here, we develop a general bottom-up approach to fabricate an emerging class of freestanding nanodiamond-based hybrid nanostructures with external functional units of either plasmonic nanoparticles or excitonic quantum dots. Precise control of the structural parameters (including size, composition, coverage and spacing of the external functional units) is achieved, representing a pre-requisite for exploring the underlying physics. Fine tuning of the emission characteristics through structural regulation is demonstrated by performing single-particle optical studies. This study opens a rich toolbox to tailor properties of quantum emitters, which can facilitate design guidelines for devices based on nitrogen-vacancy centres that use these freestanding hybrid nanostructures as building blocks. PMID:27273426

  19. Nanodiamond-based nanostructures for coupling nitrogen-vacancy centres to metal nanoparticles and semiconductor quantum dots

    Science.gov (United States)

    Gong, Jianxiao; Steinsultz, Nat; Ouyang, Min

    2016-06-01

    The ability to control the interaction between nitrogen-vacancy centres in diamond and photonic and/or broadband plasmonic nanostructures is crucial for the development of solid-state quantum devices with optimum performance. However, existing methods typically employ top-down fabrication, which restrict scalable and feasible manipulation of nitrogen-vacancy centres. Here, we develop a general bottom-up approach to fabricate an emerging class of freestanding nanodiamond-based hybrid nanostructures with external functional units of either plasmonic nanoparticles or excitonic quantum dots. Precise control of the structural parameters (including size, composition, coverage and spacing of the external functional units) is achieved, representing a pre-requisite for exploring the underlying physics. Fine tuning of the emission characteristics through structural regulation is demonstrated by performing single-particle optical studies. This study opens a rich toolbox to tailor properties of quantum emitters, which can facilitate design guidelines for devices based on nitrogen-vacancy centres that use these freestanding hybrid nanostructures as building blocks.

  20. Non-isothermal kinetic analysis of thermal dehydration of La2(CO3)3·3.4H2O in air%La2(CO3)3·3.4H2O在空气中热脱水的非等温动力学分析

    Institute of Scientific and Technical Information of China (English)

    张湘辉; 何川; 汪灵; 刘菁; 邓苗; 冯谦

    2014-01-01

    采用水热法合成单相La2(CO3)3·3.4H2O。采用XRD、FTIR以及DTA-TG对La2(CO3)3·3.4H2O在30~1000°C的热分解过程、中间及最终产物进行表征。在非等温条件下对La2(CO3)3·3.4H2O在30~366°C范围内的热脱水动力学进行研究。采用Flynn-Wall-Ozawa及Friedman 等转化法计算其反应活化能并对其反应阶段进行分析。采用多元非线性回归程序确定其最可能的反应机理及动力学参数。结果表明,La2(CO3)3·3.4H2O 的热脱水为三步竞争反应,一个 n 序列初始反应后为 n 序列竞争反应(FnFnFn 机理)。经最可能的反应机理计算所得的活化能与Friedman等转化法的计算结果非常接近,拟合后的TG及 DTG曲线与原始曲线能较好地吻合。%The single phase La2(CO3)3·3.4H2O was synthesized by hydrothermal method. The thermal decomposition and intermediates and final solid products of La2(CO3)3·3.4H2O from 30 to 1000 °C were characterized by XRD, FTIR and DTA-TG. The kinetics of dehydration of La2(CO3)3·3.4H2O in the temperature range of 30-366 °C was investigated under non-isothermal conditions. Flynn-Wall-Ozawa and Friedman isoconversion methods were used to calculate the activation energy and analyze the reaction steps; multivariate non-linear regression program was applied to determine the most probable mechanism and the kinetic parameters. The results show that the thermal dehydration of La2(CO3)3·3.4H2O is a kind of three-step competitive reaction, and controlled by ann-order initial reaction followed byn-order competitive reaction (FnFnFnmodel). The activation energy matching with the most probable model is close to value obtained by Friedman method. The fitting curves match the original TG-DTG curves very well.

  1. Interaction of [Rh2(O2CCH3)4(H2O)2] and [Rh2(O2CCH(OH)Ph)2(phen)2(H2O)2](O2C-CH(OH)Ph)2 With Sulfhydryl Compounds and Ceruloplasmin

    OpenAIRE

    Jakimowicz, Piotr; Ostropolska, Lucja; Pruchnik, Florian P.

    2000-01-01

    The interaction of binuclear rhodium(II) complexes [Rh2(OOCCH3)4(H2O)2], [Rh2{OOCCH(OH)Ph}2(phen)2(H2O)2] {OOCCH(OH)Ph}2, [Rh2(OOCCH3)2(bpy)2(H2O)2](OOCCH3)2 and [Rh2Cl2(OOCMe)2(bpy)2](3H2O) with ceruloplasmin, cysteine, glutathione and coenzyme A have been investigated using. UV-Vis and CD spectroscopies. The complexes containing phen or bpy at pH = 7.4 and 4.0 are readily reduced with sulfhydryl compounds, while rhodium(II) acetate is relatively stable in these conditions. Complex [Rh2{OOCC...

  2. Polynuclear complexes with bridging pyrophosphate ligands: synthesis and characterisation of {[(bipy)Cu(H2O)(mu-P2O7)Na2(H2O)6] x 4H2O}, {[(bipy)Zn-(H2O)(mu-P2O7)Zn(bipy)]2 x 14H2O} and {[(bipy)(VO)2]2(mu-P2O7)] x 5H2O}.

    Science.gov (United States)

    Doyle, Robert P; Nieuwenhuyzen, Mark; Kruger, Paul E

    2005-12-01

    The reaction in water of M(II) ions (M = Cu, 1; Zn, 2; VO, 3) with 2,2'-bipyridine (bipy) followed by Na4P2O7 leads to the formation of three new complexes which feature the pyrophosphate anion, P2O7(4-), as a bridging ligand. Single crystal X-ray diffraction revealed 1 to be {[(bipy)Cu(H2O)(micro-P2O7)Na2(H2O)6] x 4H2O}, and 2 as a tetranuclear Zn(II) complex, {[(bipy)Zn(H2O)(micro-P2O7)Zn(bipy)]2 x 14H2O}. The structure of 1 consists of a mononuclear [(bipy)Cu(H2O)(P2O7)]2- unit that links via a pyrophosphate bridge to two Na atoms. The hydrated six-coordinate Na atoms themselves join together through bridging water molecules to generate a 2D Na-water sheet. The structure of 2 consists of a tetranuclear Zn(II) cluster (dimer-of-dimers) with two pyrophosphate ligands bridging between four metal centres. Adjacent clusters interact through face-to-face pi-pi interactions via the bipy ligands to yield a 2D sheet. Adjacent sheets pack in register to create channels, which are filled by the water molecules of crystallisation. An intricate 2D H-bonded water network separates adjacent sheets and encapsulates the tetranuclear clusters. Aspects of the pyrophosphate coordination modes in 1 and 2 are of structural relevance to those found within the inorganic pyrophosphatases. Compound 3, {[(bipy)(VO)2]2(micro-P2O7)] x 5H2O}, was isolated as an insoluble lime-green powder. Its dinuclear structure was elucidated from elemental and thermal analysis, magnetic susceptibility measurement and IR spectroscopy. The latter displayed characteristic bridging pyrophosphate and signature V=O stretches, which were corroborated by contrast to the IR spectra of 1 and 2 and through comparison with those found in the structurally characterised dinuclear complex, {[(bipy)Cu(H2O)]2(micro-P2O7) x 7H2O}, 4. PMID:16471055

  3. Ferroelectric TGS ((NH sub 2 CH sub 2 COOH) sub 3 centre dot H sub 2 SO sub 4) under high pressure

    CERN Document Server

    Kobayashi, Y; Furuta, H; Endo, S; Deguchi, K

    2002-01-01

    The ferroelectric transition temperature T sub c of (NH sub 2 CH sub 2 COOH) sub 3 centre dot H sub 2 SO sub 4 (TGS), which is a typical order-disorder-type ferroelectric, was determined by dielectric constant and Raman scattering measurements under high pressure. T sub c increased, passed through a maximum and then decreased slightly with increasing pressure, and then abruptly dropped at about 2.5 GPa, where a transition to a new high-pressure phase was confirmed to exist. A tentative p-T phase diagram was proposed for TGS.

  4. Activation of silicon quantum dots and coupling between the active centre and the defect state of the photonic crystal in a nanolaser

    Institute of Scientific and Technical Information of China (English)

    Huang Wei-Qi; Chen Hang-Qiong; Shu Qin; Liu Shi-Rong; Qin Chao-Jian

    2012-01-01

    A new nanolaser concept using silicon quantum dots (QDs) is proposed.The conduction band opened by the quantum confinement effect gives the pumping levels.Localized states in the gap due to some surface bonds on Si QDs can be formed for the activation of emission.An inversion of population can be generated between the localized states and the valence band in a QD fabricated by using a nanosecond pulse laser.Coupling between the active centres formed by localized states and the defect states of the two-dimensional (2D) photonic crystal can be used to select the model in the nanolaser.

  5. Diffuse reflection infrared Fourier transform (DRIFT) spectra and high-temperature DRIFT spectra of beta-Ni(IO3)2.4H2O, Ni(IO3)2.2H2O, Mg(OH)2, and Zn(OH)F: novel embedding materials.

    Science.gov (United States)

    Pracht, G; Weckler, B; Lutz, H D

    2003-10-01

    Diffuse reflection infrared Fourier transform (DRIFT) spectra of the hydroxides Mg(OH)2 and Zn(OH)F and the iodate hydrates beta-Ni(IO3)2.4H2O and Ni(IO3)2.2H2O have been recorded at ambient and high temperature. Spectra without shifts of the band maxima compared to those of conventional infrared transmission spectra and without inversion of the bands were obtained by dilution of the compounds to about 2-10% with an appropriate embedding material. alpha-Al2O3, TiO2, ZrO2, PbF2, MgO, BaO, ZnO, Na2SiO3, SiO2 (aerosil), and powdered copper, aluminum, and magnesium were tested as diluents for hydrates and hydroxides, especially at elevated temperatures, as alternatives for the commonly used KBr. Thus, alpha-Al2O3, PbF2, and powdered copper were established as the most favorable diluents. Using these novel embedding materials, high-temperature DRIFT spectra are obtainable at temperatures not accessible with KBr discs. Dehydration and decomposition of the iodate hydrates under study were shown by change or disappearance of the respective water bands. PMID:14639754

  6. Synthesis, characterization, single crystal X-ray structure, EPR and theoretical studies of a new hybrid inorganic-organic compound [Cu(Hdien)2(H2O)2](pnb)4·4H2O and its structural comparison with related [Cu(en)2(H2O)2](pnb)2

    Science.gov (United States)

    Kumar, Santosh; Sharma, Raj Pal; Venugopalan, Paloth; Witwicki, Maciej; Ferretti, Valeria

    2016-11-01

    A new hybrid inorganic-organic compound [Cu(Hdien)2(H2O)2](pnb)4·4H2O (1) (where pnb = p-nitrobenzoate), in which the tridentate ligand diethylenetriamine (dien) shows an unusual coordination behavior acting as a bidentate ligand when present in its monoprotonated form (Hdien+) has been synthesized by the reaction of copper(II) p-nitrobenzoate and slight excess of dien in methanol-water mixture (4:1v/v). Re-crystallization of the violet precipitated product from hot water gave single crystals suitable for X-ray diffraction studies. The newly synthesized compound 1 has been characterized by spectroscopic techniques (UV-Vis, FT-IR, EPR), and theoretical methods (DFT and MRCI/SORCI). Single crystal X-ray structure determination revealed the existence of the cationic species [Cu(Hdien)2(H2O)2]4+, four p-nitrobenzoate as counter anions and four water molecules are present as solvent of crystallization. Packing analyses of title compound as well as of the structurally similar [Cu(en)2(H2O)2](pnb)2,2 has shown similarities in the crystalline architecture that both hybrid inorganic-organic compounds is stabilized by various non-covalent interactions such as N-H⋯O, C-H⋯O, O-H⋯O etc.

  7. Synthesis and Crystal Structure of a Two-dimensional Zinc(Ⅱ) Coordination Polymer:[Zn2(DTB)(DMF)4(H2O)2]n (DTM= 1,4-Dinitro-2,3,5,6-tetracarboxylatebenzene Tetravalent Anion; DMF = Dimethylformamide)

    Institute of Scientific and Technical Information of China (English)

    石敬民; 尹海亮; 吴长举

    2004-01-01

    A two-dimensional coordination polymer [Zn2(DTB)(DMF)4(H2O)2]n has been synthesized by 1,4-dinitro-2,3,5,6-tetracarboxylatebenzenic acid and hydrate zinc perchlorate in the solutions of DMF and H2O. The crystal belongs to the triclinic system, space group P with a = 8.887(6), b = 9.225(6), c = 9.828(7)(°A), α = 85.249(11), β = 74.863(11), γ= 86.510(13)°, V = 774.4(9), Z = 1, C22H32N6O18Zn2, Mr = 799.28, Dc = 1.714 g/cm3, F(000) = 410 and μ= 1.639 mm-1. The structure was refined to R = 0.0539 and wR = 0.1161 for 1584 observed reflections (I > 2б(I)). In the complex there exist two kinds of coordination environments for the zinc(Ⅱ) ions and a two-dimensional sheet is formed via the coordination of carboxylates and zinc(Ⅱ) ions.

  8. 难浸金矿FeS2-FeAsS-KMnO4-H2O系的E-pH研究%E-pH Study of FeS2-FeAsS-KMnO4-H2O System of Refractory Gold

    Institute of Scientific and Technical Information of China (English)

    周姣; 蒋中刚; 刘华龙; 唐道文; 刘现超; 燕璞

    2014-01-01

    通过热力学计算绘制了298.15 K条件下FeS2-FeAsS-KMnO4-H2O系的E-pH图,找出了较理想的KMnO4氧化FeS2和FeAsS的电位和pH预处理条件。实验表明,经高锰酸钾预处理后,包裹金的黄铁矿和毒砂被打开,这一结果为难浸金矿氧化预处理提供重要的理论参考。%The E-pH diagram of FeS2-FeAsS-KMnO4-H2O system in 298.15 K was drawn through thermodynamic calculations. The ideal pretreatment condition for pH and electric potential were found for KMnO4 oxidation FeS2 and FeAsS from the E-pH diagram. The result showed that the pyrite and arsenopyrite wrapped gold is opened through potassium permanganate pretreatment. This result may provide some theoretical criterion for oxidation pretreatment of refractory gold.

  9. Hydrothermal synthesis and structure of [(C4N2H12)3][P2Mo5O23]$\\cdot$H2O and [(C3N2H12)3][P2Mo5O23]$\\cdot$4H2O

    Indian Academy of Sciences (India)

    S V Ganesan; Srinivasan Natarajan

    2005-05-01

    Two new compounds, [(C4N2H12)3][P2Mo5O23]$\\cdot$H2O, I, and [(C3N2H12)3][P2Mo5O23]$\\cdot$4H2O, II, have been prepared employing hydrothermal methods in the presence of aliphatic organic amine molecules. Both the compounds possess the same polyoxoanion, pentamolybdatobisphosphate, (P2Mo5O23)6-. The anions consist of a ring of five MoO6 distorted octahedra with four edge connections and one corner connection. The phosphate groups cap the pentamolybdate ring anion on either side. The anion is stabilized by strong hydrogen bonds involving the hydrogen atoms of the amine molecules and the oxygen atoms of the polyoxoanion and water molecules. Crystal data: I, monoclinic, space group = 21/ (no. 14), mol. wt. = 1192.1, = 9.4180(1), = 18.1972(3), = 19.4509(1) Å, = 103.722(1)°, = 3238.37(7) Å3, = 4; II, triclinic, space group = 1 (no. 2), mol. wt. = 1210.1, = 9.5617(9), = 13.3393(12), = 13.7637(12) Å, = 88.735(1), = 75.68(1), = 87.484(2)°, = 1699.2(3) Å3.

  10. Synthesis, crystal structure and properties of a new organic-inorganic hybrid Dawson-like polyoxotungstate [Co(2,2'-bpy)3]2[Co(2,2'-bpy)2Cl][Co(2,2'-bpy)2]H2-[SbW18O60]·4H2O

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    A new organic-inorganic hybrid polyoxometalate based on Dawson-like polyoxotungstate anion [SbW18O60]9-, formulated [Co(2,2'-bpy)3]2[Co(2,2'-bpy)2Cl][Co(2,2'-bpy)2]H2[SbW18O60]·4H2O (2,2'-bpy= 2,2(-bipyridine) has been synthesized from Sb2O3, Na2WO4, CoCl2, and 2,2'-bipyridine materials by hydrothermal method, and which was characterized by elemental analyses, IR, XPS, EPR, TG, and X-ray single crystal diffraction. Structure analysis shows that the polyoxoanion self-assembled under hydrothermal conditions consists of a Dawson-like polyoxotungstate cluster anion [SbW18O60]9- encapsulating a pyramidal {SbO3} group within the {W18} cluster cage. EPR spectra show that the high-spin octahedral CoⅡ and low-spin CoⅡ ions coexist in the title compound. Magnetic properties indicate that the compound is antiferromagnetic.

  11. Synthesis and Crystal Structure of a Three-dimensional Manganese(Ⅱ)Complex (tataH)2[Mn(pydc)2]·4H2O(tata= 2,4,6-Triamino-1,3,4,-triazine,pydcH2= Pyridine-2,6-dicarboxylic Acid)

    Institute of Scientific and Technical Information of China (English)

    SUN Yi-Feng; LI Ji-Kun; CUI Yi-Ping

    2008-01-01

    A manganese(Ⅱ) complex (tataH)2[Mn(pydc)2]·4H2O (C20H28MnN14O12, Mr = 711.50, tata = 2,4,6-triamino-1,3,5-triazine, pydcH2 = pyridine-2,6-dicarboxylic acid) has been synthesized and its crystal structure was determined by single-crystal X-ray diffraction. The crystal belongs to the triclinic system, space group P1, with a = 9.9847(3), b = 10.9813(3), c = 15.2616(5) (A), α =101.5310(10), β = 90.2610(10), γ = 116.4600(10)°, V = 1459.44(8) A3, Z = 2, Dc = 1.619 g/cm3, μ = 0.539 mm-1, F(000) = 734, the final R = 0.0292 and wR = 0.0745. In the crystal the MnⅡ atom is six-coordinated by four carbonyl oxygen atoms and two pyridine nitrogen atoms from two tridentate H-bonded tetramer. The molecules are packed in a three-dimensional framework structure by the combination of O-H…O,N-H…O and N-H…N hydrogen bonds between (tataH)+,[Mn(pydc)2]2- and crystal water.

  12. NaOH-Na2H2SiO4-H2O体系渗透系数的等压法测定及离子作用模型%Isopiestic Determination of Osmotic Coefficients and Representation with Ion-interaction Model for NaOH-Na2H2SiO4-H2O System

    Institute of Scientific and Technical Information of China (English)

    肖刘萍; 刘士军; 宋婷; 陈启元

    2011-01-01

    The isopiestic molalities have been measured for the system NaOH-Na2H2SiO4-H20 by isopi- estic method in the ionic strength ranges from 0.5695 to 6.4775 mol·kg-1 and modulus (mole ratio of SiO2 to Na20) range from 0.1461 to 0.3158 at 313.15 K, and the osmotic coefficients and water activities have been calculated from the measurements. The experimental data have been represented by the Pitzer model of osmotic coefficient. The Pitzer ion interaction parameters were evaluated from experimental data using multiple regression. The experimental data of osmotic coefficients measured and calculated by using the Pitzer model are in reasonable agreements. It is shown that the Pitzer model can describe the system's thermody- namic properties well. The mean activity coefficients of NaOH and Na2H2SiO4 were also calculated for the NaOH-NaEH2SiO4-H2O system, and these calculations establish their variations with ionic strength and modulus. The mean activity coefficients of NaOH were compared with those calculated from Mckay-Perring equation, and it was pointed out that the application scope of Mckay-Perring equation for NaOH- NaEH2SiO4-H2O system.%采用等压法测定了313.15K下NaOH-Na2H2SiO4-H2O体系在0.5695~6.4775mol·kg-1的离子强度范围及0.1461~0.3158的模数(SiO2与Na2O的物质的量比)范围内的等压平衡浓度,计算了该混合体系的渗透系数和水活度.用Pitzer离子相互作用模型对实验结果进行了参数化研究,拟合求取了Pitzer离子相互作用参数.用Pitzer模型计算的渗透系数值与实验结果一致,说明该模型能较好的描述NaOH—Na2H2SiO4-H2O体系的热力学性质.用Pitzer模型计算得到了该体系的各组分平均活度系数随离子强度及模数的变化规律,并与Mckay—Perring方程计算得到的NaOH的平均活度系数进行了比较,指出Mckay—Perring方程的适用性.

  13. Co-sensitization promoted light harvesting with a new mixed-addenda polyoxometalate [Cu(C12H8N2)2]2[V2W4O19]·4H2O in dye-sensitized solar cells.

    Science.gov (United States)

    Xu, Sha-Sha; Chen, Wei-Lin; Wang, Yan-Hua; Li, Yang-Guang; Liu, Zhu-Jun; Shan, Chun-Hui; Su, Zhong-Min; Wang, En-Bo

    2015-11-14

    A di-vanadium-substituted Lindqvist-type polyoxometalate [Cu(C12H8N2)2]2[V2W4O19]·4H2O (1) was hydrothermally synthesized and characterized structurally by single crystal X-ray diffraction analysis. X-ray photoelectron spectroscopy and energy disperse spectroscopy tests further prove the existence of vanadium. Ultraviolet photoelectron spectroscopy and density functional theoretical studies indicate that the energy level of 1 matches well with the conduction band of the TiO2. Furthermore, considering the semiconductor-like nature of 1 and the introduction of transition metal element Cu synchronously extends the absorption to the visible region, which should also be beneficial to the photovoltaic device performance. 1-Doped TiO2 composites (denoted as 1@TiO2) have been successfully fabricated by a simple sol-gel method, and introduced into the dye-sensitized solar cells (DSSCs) as co-sensitizers in N719-sensitized photoanodes by mixing 1@TiO2 with P25 nanoparticles with different weight ratios to enhance the photoelectric conversion efficiency. The investigations show that the DSSC assembled with 1@TiO2/19P25 photoanode has the best performance and the overall improvement of the efficiency is 21.6% compared with pure P25. Furthermore, the electrochemical impedance spectroscopy and open-circuit voltage decay investigations show that the cosensitization of 1 and N719 can promote electron transfer and restrain charge recombinations in the DSSCs, resulting in a longer electron lifetime.

  14. Activity Coefficients of CuSO4-NiSO4-H2 O System at 298.15 K%298.15K时CuSO4-NiSO4-H2O三元溶液体系的活度

    Institute of Scientific and Technical Information of China (English)

    陈香; 刘士军; 黄华强

    2014-01-01

    The osmotic coefficients of the CuSO4-NiSO4-H2 O system at 298.15 K was determined by the iso-piestic method in the ion strength range from 0.387 7~5.798 6 mol/kg.The experimental data were represented by the pitzer ion-interaction model, and the Pitzer ion interaction parameters were obtained from resulting osmotic coefficients by multiple linear regression.The osmotic coefficients values determined experimentally and those cal-culated by the model in reasonable agreement indicated that the Pitzer model can describle the system's thermody-namics properties well at 298 .15 K.The function between acitivity coefficients and the ionic strength was studied.%用等压法测定了298.15 K时CuSO4-NiSO4-H2 O溶液体系在离子强度范围为0.3877~5.7986 mol· kg-1内的渗透系数,用Pitzer离子相互作用模型对实验结果进行参数化研究,获得了CuSO4和NiSO4纯盐参数以及混盐参数,渗透系数的模型计算值与实验值的相对偏差为±0.03,表明Pitzer模型能较好描述298.15 K时该溶液体系的热力学性质;得到了该溶液体系中离子平均活度系数随离子强度的变化规律.

  15. Assembly of a New Cyano-bridged 4f-3d Dimer Sm(DMSO)4-(H2O)3Cr(CN)6 and Crystal Structure of [K3(18-crown-6)3-(H2O)4] Cr(CN)6 ·3H2O

    Institute of Scientific and Technical Information of China (English)

    周北川; 王宏根; 等

    2003-01-01

    A new syano-bridged binuclear 4f-3d complex Sm(DMSO)4-(H2O)3Cr(CN)6 was synthesized and characterized by single crystal structure analysis.It crystallizes in monoclinic,space group P21 with a=0.9367(3)°and Z=2,In this binuclear complex,Sm atom is eight coordinated and linked to the Cr atom by a cyano bridge,The molecules packs to form 3D structure due to the hydrogen bonds among them. [K3(18-crown-6)3-(H2O)4] Cr(CN)6 ·3H2O(18-C-6 represents 18-crown-6-ether)that was synthesized as a byproduct in the preparation of a Gd-Cr complex is also structurally characterized.Crystal data:triclinic,space group p-1 with a=1.0496(7)nm,b=1.1567(14)nm,c=1.3530(13)nm,α=94.15(9)°,β=96.04(8)°,γ=95.25(9)° and Z=1, [K3(18-crown-6)3-(H2O)4] Cr(CN)6 ·3H2O consists of ionic [K3(18-crown-6)3-(H2O)4]3+ and [Cr(CN)6]3- pairs,of which the [K3(18-C-6)3(H2O)4]3+ ion is a trinuclear cluster connected by water,and K atome are eight coordinated by eight oxygen atoms of one 18-C-6 and two water molecules.

  16. Optical excitation in doped quasi-one-dimensional antiferromagnet (CsMnCl3 centre dot 2H2O+Cu2+)

    International Nuclear Information System (INIS)

    In the wide range of wavelengths and temperatures, the spectra of light absorption and luminescence excitation as well as the emission decay kinetics of a quasi-one-dimensional dielectric crystal CsMnCl3 centre dot 2H2O doped with copper ions (molar concentration 0-3%) are studied. The conclusion is made of the exchange of electronic excitation energy being possible between the matrix and dopant subsystems only in the lowest excited state due to migration of excitation and their trapping by excitation traps of the copper origin. From the analysis of the shape of decay kinetics curves of the matrix luminescence of the crystal, the values of hopping (along the chains of manganese ions) and trapping rates of magnetic excitons are determined

  17. Study on phase equilibria in Na2 B4 O7 -NaBr-Na2 SO4 -H2O quaternary system at 348 K%Na2B4O7-NaBr-Na2SO4-H2O四元体系348K相平衡研究

    Institute of Scientific and Technical Information of China (English)

    宁慧逸; 桑世华; 王丹; 曾晓晓

    2012-01-01

    采用等温溶解平衡法研究Na2B4O7 -NaBr-Na2SO4-H2O四元体系在348 K的相平衡关系,测定了平衡液相的溶解度和密度.根据实验数据绘制相应相图.该四元体系相图中有1个共饱点E,3条单变量曲线E1E,E2E,E3E,3个结晶区的平衡固相分别为:NaBr,Na2SO4和Na2B4O7 · 5H2O.研究结果表明:该四元体系无复盐和固溶体生成,属于简单四元体系,NaBr对Na2B4O7·5H2O和Na2SO4有较强的盐析作用.并对NaBr和Na2B4O7在不同温度下含有的结晶水数进行了对比分析,简要讨论了密度变化规律.%The solubilities and densities of solution in Na2B4O7-NaBr- Na2SO4-H2O quaternary system at 348 K were determined by isothermal equilibrium method. Based on the experimental data, the equilibrium phase diagram was plotted, which consists of one invariant E, three univariant curves (E1E, E2E and E3E) , and three crystallization fields corresponding to NaBr, Na2SO4 and Na2B4O7 ? 5H2O. The experimental results indicate that the quaternary system is of simple eutectic type and no double salt and solid solution, and sodium bromide has the salting-out effect on Na2B4O7 ? 5H2O and Na2SO4. The densities transformation rules were discussed.

  18. Crystal and molecular structure of Sr2(Edta) . 5H2O, Sr2(H2Edta)(HCO3)2 . 4H2O, and Sr2(H2Edta)Cl2 . 5H2O strontium ethylenediaminetetraacetates

    International Nuclear Information System (INIS)

    Three Sr2+ compounds with the Edta4- and H2Edta2- ligands-Sr2(Edta) . 5H2O (I), Sr2(H2Edta)(HCO3)2 . 4H2O (II), and Sr2(H2Edta)Cl2 . 5H2O (III)-are synthesized, and their crystal structures are studied. In I, the Sr(1) atom is coordinated by the hexadentate Edta4- ligand following the 2N + 4O pattern and by two O atoms of the neighboring ligands, which affords the formation of zigzag chains. The Sr(2) atom forms bonds with O atoms of five water molecules and attaches itself to a chain via bonds with three O atoms of the Edta4- ligands. The Sr(1)-O and Sr(2)-O bond lengths fall in the ranges 2.520(2)-2.656(3) and 2.527(3)-2.683(2) A, respectively. The Sr(1)-N bonds are 2.702(3) and 2.743(3) A long. In II and III, the H2Edta2- anions have a centrosymmetric structure with the trans configuration of the planar ethylenediamine fragment. The N atoms are blocked by acid protons. In II, the environment of the Sr atom is formed by six O atoms of three H2Edta ligands, two O atoms of water molecules, and an O atom of the bicarbonate ion, which is disordered over two positions. In III, the environment of the Sr atom includes six O atoms of four H2Edta2- ligands and three O atoms of water molecules. The coordination number of the Sr atoms is equal to 8 + 1. In II and III, the main bonds fall in the ranges 2.534(3)-2.732(2) and 2.482(2)-2.746(3) A, whereas the ninth bond is elongated to 2.937(3) and 3.055(3) A, respectively. In II, all the structural elements are linked into wavy layers. The O-H-O interactions contribute to the stabilization of the layer and link neighboring layers. In III, hydrated Sr2+ cations and H2Edta- anions form a three-dimensional [Sr2(H2Edta)(H2O)3]n2n+ framework. The Cl- anions are fixed in channels of the framework by hydrogen bonds with four water molecules. In II and III, the N-H groups form four-center N-H-O3 hydrogen bonds, which include one intermolecular and two intramolecular components. PACS numbers: 61.66.Hq

  19. NaOH-NaAl(OH)4-H2O溶液体系渗透系数的测定及离子作用模型%Determination of Osmotic Coefficients and Representation with Ion-interaction Model for NaOH-NaAl (OH) 4-H2O System at 303.15 K

    Institute of Scientific and Technical Information of China (English)

    宋婷; 刘士军; 肖刘萍; 陈启元

    2012-01-01

    用等压法测定了在303.15 K时总碱质量摩尔浓度mNaOH(T)[mNaOH+mNaAl(OH)4]从0.61 mol/kg到5.72mol/kg,苛性比αK[ mNaOH(T) /mNaAl( OH)4]从1.98到7.04的NaOH-NaAl( OH)4-H2O溶液体系的等压平衡浓度和渗透系数,并得到该溶液体系的水活度.用Pitzer模型对实验结果进行了参数化研究,拟合求得了离子相互作用参数.用Pitzer模型计算的渗透系数值与实验结果一致.用获得的参数计算了NaOH和NaAl( OH)4在NaOH-NaAl(OH)4-H2O溶液体系中的活度系数,其值随总碱质量摩尔浓度的增加呈增加的趋势.%The isopiestic equilibrium molalities and the osmotic coefficients for the NaOH-NaAl(OH)4-H2O system were measured using isopiestic method. At 303. 15 K with the total alkli molality[mNa0H(T)= mNa0H + mNaAi(OH)4] from 0. 61 mol/kg to 5.72 mol/kg and molar ratio of Na2O to Al2O3(αK) [mNa0H(T)/mNiA1(0H)4] from 1. 98 to 7. 04. The experimental data were represented by the Pitzer model. The Pitzer ion interaction parameters were evaluated from experimental data using multiple regression. The measured data of osmotic coefficients are in reasonable agreements with those calculated by the model. The activity coefficients of NaOH and NaAl (OH) 4 in the system were calculated from the ion interaction model parameterized, and the values increased with the total alkli molality increasing. These studies are useful to improve the thermodynamic model for sodium aluminate solutions systems and sodium aluminosilicate solutions systems.

  20. NMR investigation on isotope effect of glycinium phosphite H sub 3 NCH sub 2 COOH centre dot H sub 2 PO sub 3

    CERN Document Server

    Ishibashi, T

    2003-01-01

    The motions of the phosphite anions and glycinium cations in H sub 3 NCH sub 2 COOH centre dot H sub 2 PO sub 3 (GPI) and its deuterated analogue (DGPI) were investigated by sup 1 H, sup 1 sup 3 C and sup 3 sup 1 P spin-lattice relaxation times T sub 1. For both GPI and DGPI, T sub 1 's of the sup 1 H, sup 1 sup 3 C and sup 3 sup 1 P nuclei reflect the amino rotation, methylene libration and motion of the phosphite anions, respectively. Activation energies obtained from T sub 1 's of sup 1 H, sup 1 sup 3 C and sup 3 sup 1 P nuclei are 28.6(2), 26.0(4) and 26.2(4) kJ/mol for GPI and are 34.9(6), 27(1), 47(2) kJ/mol for DGPI, respectively. The deuterium substitution increases E sub a for the motion influenced by the hydrogen bonding. In all the observed motions, correlation times of DGPI are larger than those of GPI. (author)

  1. Aspects of the historical development of targetry for heavy ions of 0.05-2000 A centre dot MeV at GSI

    CERN Document Server

    Folger, H

    1999-01-01

    The progressively improved GSI accelerators provide beams of heavy ions from energies of 0.05-2000 A centre dot MeV at high particle intensities now. Therefore, a wide variety of common and new heavy-ion target techniques had to be installed and developed during the past 25 years to prepare and characterize self-supported or backed heavy-ion-targets of chemical elements and compounds from hydrogen (as polyethylene) to uranium. The thickness ranged from 2x10 sup - sup 6 to 20 g/cm sup 2 for beam spots of about 5 mm in diameter. Homogeneity, surface structure or individual shape had to be adapted to the needs of each experiment. Special setups were required for targets of poisonous materials, of highly enriched stable isotopes or those of radioactive species in minute amounts. The capability of thin-layer technologies was as well applied to prepare and measure stripper foils or various high-vacuum deposits for experimental or accelerator purposes. The development of different rotating target wheels and control ...

  2. The effect of taurine on basal forebrain ChaT neurons of rats induced by sub-chronic MnCl2·4H2O%牛磺酸对亚慢性染锰大鼠基底前脑胆碱能神经细胞的干预研究

    Institute of Scientific and Technical Information of China (English)

    陆彩玲; 卢海艳; 黄玲; 刘楠楠; 黄世文; 书潇湘; 唐深; 郭松超

    2011-01-01

    Objective To study the effect of taurine on basal forebrain choline acetyltransferase positive cells of rats induced by MnCl2-4H2O. Methods SPF SD rats were randomly assigned into 5 groups; Control, MnCl2-treated I group, MnCl2-treated II group, Taurine-prevented group and Taurine-treated group respectively. Water Morris Maze is utilized to probe rats learning and memory capacity after 8 weeks injection. Morphological change and number of ChaT positive neurons from basal forebrain were observed under Nikon microscope after immunohistochemistry. Results The average escapes latencies in both taurine-prevented and taurine-treated are evidently shorter than those in MnCl2-treated(P <0.05). The probing times in taurine-prevented is obviously increase than that in MnCl2-treated I group ( P < 0.05 ). There is no significance defference between taurine-treated and MnCl2 -treated II group. The ChaT positive neurons number of basal forebrain vDB/hDB in MnCl2-treated group is less than that in control group(P <0. 05). Taurine-prevented reverse distinctly hDB ChaT number induced by MnCl2(P <0.05). The vDB ChaT positive neurons number in taurine-treated is markedly less than that in MnCl2-treated II group (P <0. 05) . Conclusion Taurine-prevented and taurine-treated can improve impaired memory and study capacity induced by Sub-chronic MnCl2 administration. Taurine-prevented may reverse markedly decreased hDB ChaT positive neurons of basal forebrain induced by MnCl2. However, It can't be detected in taurine-treated group.%目的 牛磺酸干预对亚慢性锰中毒大鼠基底前脑胆碱能神经细胞的影响.方法 SPF级雄性SD大鼠随机分为生理盐水对照组、染锰Ⅰ组、牛磺酸预防组、染锰Ⅱ组、牛磺酸治疗组.各组大鼠染毒结束后进行水迷宫实验检测大鼠空间学习记忆能力的变化,免疫组化染色观察胆碱乙酰转移酶(Choline acetyltransferase,ChaT)阳性神经元形态及数量变化.结果 牛磺酸预防组平均

  3. Paravinogradovite, (Na,□)2 [(Ti4+, Fe3+)4 {Si2 O6}2 {Si3 Al O10} (OH)4] H2O, a new mineral species for the Khibina alkaline massif, Kola Peninsula, Russia: description and crystal structure

    International Nuclear Information System (INIS)

    resulting empirical formula on the basis of 26 anions (including OH = 4 apfu and excluding H2O) is (Na2. 293K0.169) (Ti4+3.386Fe3+0.471 Mg0.029 Nb0.034) (Si6.626 Al1.098 Be0.276) O22 (OH)4 (H2O)1.16. There are prominent endothermic effects at 280 and 460oC; the principal losses in weight are within the temperature ranges 150-400 (3.8%) and 400-600oC (2.8%), and the total loss in weight at 980oC is 7.1%. The principal absorptions in the infrared are as follows: 3520, 3330, 3240, 1633, 1105, 989, 940, 725, 691, 638, 599, 568, 523, 459 and 418 cm-1, indicative of both OH and H2O in the structure. The name recognizes the close structural and chemical relations between paravinogradovite and vinogradovite, ideally Na5 Ti4+4 (Si7Al) O26 (H2O)3. The crystal structure of paravinogradovite was solved by direct methods and refined to an R1 index of 4.5% based on 4373 observed [F0> 4σF] unique reflections measured with MoKα X-radiation and a Bruker P4 diffractometer with a CCD detector. Four (SiO4) tetrahedra form pyroxene-like [Si2O6] chains, and three (SiO4) tetrahedra and one (AlO4) tetrahedron form vinogradovite-like [Si3AlO10] chains parallel to [100]. (MO6) octahedra (M ∼ Ti4+) share common edges to form two distinct zig-zag brookite-like chains along [100]. One chain is decorated by (XO6) octahedra (X ∼ Na) and linked into a sheet parallel to (100) by [Si3AlO10] chains. The other distinct brookite-like chain is not decorated by (XO6) octahedra, but is linked into a sheet parallel (100) by [Si3AlO10] chains. Chains of tetrahedra and chains of octahedra link to form a framework with channels along [100]. These channels contain disordered (H2O) groups, the A(5) site partly occupied (14%) by K, and the A(1)-A(4) sites partly occupied (15-19%) by Na, giving a channel content of [Na0.72K0.14 (H2O)1.16]. The triclinic cell of paravinogradovite is related to the C-centered monoclinic cell of vinogradovite, ideally Na5 Ti4+4 (Si7Al) O26 (H20)3 [monoclinic, a 24.490(10), b 8

  4. Synthesis and Crystal Structure of a Novel Tetranuclear Yttrium Complex With Proline Ligands at High pH Value%高pH下钇-L-脯氨酸四核配合物[Y4(HPrO)4(PRO)2 (μ3-OH)4 (H2O)7] (ClO4)6@6H2O的合成与晶体结构*

    Institute of Scientific and Technical Information of China (English)

    陈德; 张大顺; 李琳; 马宝清; 金天柱

    2000-01-01

    在水溶液中,调节pH至6.3,合成了高氯酸钇与L-脯氨酸的配合物[Y4(HPrO)4(PrO)2(μ3-OH)4(H2O)7](CIO4)6@6H2O单晶,并测定了其晶体结构.该晶体属菱形晶系,R3空间群,晶胞参数:a=b=c=12.786 3(15)A,α=β=γ=100.217(17)0,V=1977.0(4)A3,Z=1,最终偏差因子R1=0.086 9,wR2=0.220 3.每个晶胞以四个Y3+通过四个μ3-OH-离子、六个脯氨酸羧基桥联成四核簇状结构.其中三个Y3+每个均与三个μ3-OH、三个羧基氧原子、两个水分子配位,其配位数为8;另一个Y3+与三个μ3-OH、三个羧基氧原子、一个水分子配位,其配位数为7.

  5. Energies and wave functions of an off-centre donor in hemispherical quantum dot: Two-dimensional finite difference approach and ritz variational principle

    Science.gov (United States)

    Nakra Mohajer, Soukaina; El Harouny, El Hassan; Ibral, Asmaa; El Khamkhami, Jamal; Assaid, El Mahdi

    2016-09-01

    Eigenvalues equation solutions of a hydrogen-like donor impurity, confined in a hemispherical quantum dot deposited on a wetting layer and capped by an insulating matrix, are determined in the framework of the effective mass approximation. Conduction band alignments at interfaces between quantum dot and surrounding materials are described by infinite height barriers. Ground and excited states energies and wave functions are determined analytically and via one-dimensional finite difference approach in case of an on-center donor. Donor impurity is then moved from center to pole of hemispherical quantum dot and eigenvalues equation is solved via Ritz variational principle, using a trial wave function where Coulomb attraction between electron and ionized donor is taken into account, and by two-dimensional finite difference approach. Numerical codes developed enable access to variations of donor total energy, binding energy, Coulomb correlation parameter, spatial extension and radial probability density with respect to hemisphere radius and impurity position inside the quantum dot.

  6. Inversion of spin levels in Ni sup 2 sup + : Zn(BF sub 4) sub 2 centre dot 6H sub 2 O at all -round compression and effect of transition coincidence

    CERN Document Server

    Krygin, I M; Nejlo, G N; Prokhorov, A D

    2001-01-01

    The study of the EPR spectrum of the Ni sup 2 sup + ion, replacing Zn sup 2 sup + in the Zn(BF sub 4) centre dot 6H sub 2 O crystals in the wide temperature range by the all-round compression in the X- and Q-ranges is carried out. The basic changes by varying temperature and pressure occur with the D parameter, characterizing the initial splitting by practically unchanged g-factor. The increase in the temperature is accompanied by the D nonlinear growth. The all-round compression linearly changes the initial splitting and leads to the change in the D-sign, signifying the spin levels inversion by 3.5 kbar. Coincidence of EPR lines, relative to different transitions, leads to the crevasse appearance in the outline of this one, that is connected with cross-relaxation inside the spin system

  7. Magnetic susceptibility of Co sup 2 sup + pairs in [Co sub 2 (ox)tpmc](ClO sub 4) sub 2 centre dot 3H sub 2 O cluster complex

    CERN Document Server

    Spasojevic, V; Sovilj, S P; Mrozinski, J

    2000-01-01

    Calculation of the magnetic susceptibility of Co sup 2 sup + pairs in the recently synthesized cobaltous cluster complex [Co sub 2 (ox)tpmc](ClO sub 4) sub 2 centre dot 3H sub 2 O has been conducted by the use of two different theoretical models. The calculated results were compared to the experimental data collected in a wide temperature region. Conclusions on both the magnetic properties of Co sup 2 sup + dimers and the validity of the proposed models have been drawn. In the temperature region above chi(T) maximum, the best results are obtained with the Heisenberg model that includes spin-orbit coupling and excited single-ion levels. In the low-temperature region anisotropy of the magnetic properties dominates and Ising dimer ground-state model gives a more appropriate description. Obtained g-values (g sub p sub a sub r sub a sub l sub l sub e sub l a=5.67, g sub p sub a sub r sub a sub l sub l sub e sub l b=5.73, and g sub p sub e sub r sub p sub e sub n sub d sub i sub c sub u sub l sub a sub r =1.54) con...

  8. Quadra-Quantum Dots and Related Patterns of Quantum Dot Molecules: Basic Nanostructures for Quantum Dot Cellular Automata Application

    Directory of Open Access Journals (Sweden)

    Somsak Panyakeow

    2010-10-01

    Full Text Available Laterally close-packed quantum dots (QDs called quantum dot molecules (QDMs are grown by modified molecular beam epitaxy (MBE. Quantum dots could be aligned and cross hatched. Quantum rings (QRs created from quantum dot transformation during thin or partial capping are used as templates for the formations of bi-quantum dot molecules (Bi-QDMs and quantum dot rings (QDRs. Preferable quantum dot nanostructure for quantum computation based on quantum dot cellular automata (QCA is laterally close-packed quantum dot molecules having four quantum dots at the corners of square configuration. These four quantum dot sets are called quadra-quantum dots (QQDs. Aligned quadra-quantum dots with two electron confinements work like a wire for digital information transmission by Coulomb repulsion force, which is fast and consumes little power. Combination of quadra-quantum dots in line and their cross-over works as logic gates and memory bits. Molecular Beam Epitaxial growth technique called 'Droplet Epitaxy' has been developed for several quantum nanostructures such as quantum rings and quantum dot rings. Quantum rings are prepared by using 20 ML In-Ga (15:85 droplets deposited on a GaAs substrate at 390'C with a droplet growth rate of 1ML/s. Arsenic flux (7'8'10-6Torr is then exposed for InGaAs crystallization at 200'C for 5 min. During droplet epitaxy at a high droplet thickness and high temperature, out-diffusion from the centre of droplets occurs under anisotropic strain. This leads to quantum ring structures having non-uniform ring stripes and deep square-shaped nanoholes. Using these peculiar quantum rings as templates, four quantum dots situated at the corners of a square shape are regrown. Two of these four quantum dots are aligned either or, which are preferable crystallographic directions of quantum dot alignment in general.

  9. Quadra-quantum Dots and Related Patterns of Quantum Dot Molecules:

    Directory of Open Access Journals (Sweden)

    Somsak Panyakeow

    2010-10-01

    Full Text Available Abstract Laterally close-packed quantum dots (QDs called quantum dot molecules (QDMs are grown by modified molecular beam epitaxy (MBE. Quantum dots could be aligned and cross hatched. Quantum rings (QRs created from quantum dot transformation during thin or partial capping are used as templates for the formations of bi-quantum dot molecules (Bi-QDMs and quantum dot rings (QDRs. Preferable quantum dot nanostructure for quantum computation based on quantum dot cellular automata (QCA is laterally close-packed quantum dot molecules having four quantum dots at the corners of square configuration. These four quantum dot sets are called quadra-quantum dots (QQDs. Aligned quadra-quantum dots with two electron confinements work like a wire for digital information transmission by Coulomb repulsion force, which is fast and consumes little power. Combination of quadra-quantum dots in line and their cross-over works as logic gates and memory bits. Molecular Beam Epitaxial growth technique called ‘‘Droplet Epitaxy” has been developed for several quantum nanostructures such as quantum rings and quantum dot rings. Quantum rings are prepared by using 20 ML In-Ga (15:85 droplets deposited on a GaAs substrate at 390°C with a droplet growth rate of 1ML/s. Arsenic flux (7–8×10-6Torr is then exposed for InGaAs crystallization at 200°C for 5 min. During droplet epitaxy at a high droplet thickness and high temperature, out-diffusion from the centre of droplets occurs under anisotropic strain. This leads to quantum ring structures having non-uniform ring stripes and deep square-shaped nanoholes. Using these peculiar quantum rings as templates, four quantum dots situated at the corners of a square shape are regrown. Two of these four quantum dots are aligned either or , which are preferable crystallographic directions of quantum dot alignment in general.

  10. Recrossing and tunnelling in the kinetics study of the OH + CH4 -> H2O + CH3 reaction

    CERN Document Server

    Suleimanov, Yury V

    2015-01-01

    Thermal rate constants and several kinetic isotope effects were evaluated for the OH + CH4 hydrogen abstraction reaction using two kinetics approaches, ring polymer molecular dynamics (RPMD), and variational transition state theory with multidimensional tunnelling(VTST/MT), based on a refined full-dimensional analytical potential energy surface, PES-2014, in the temperature range 200-2000 K. For the OH + CH4 reaction, at low temperatures, T = 200 K, where the quantum tunnelling effect is more important, RPMD overestimates the experimental rate constants due to problems associated with PES-2014 in the deep tunnelling regime and to the known overestimation of this method in asymmetric reactions, while VTST/MT presents a better agreement, differences about 10%, due to compensation of several factors, inaccuracy of PES-2014 and ignoring anharmonicity. In the opposite extreme, T = 1000 K, recrossing effects play the main role, and the difference between both methods is now smaller, by a factor of 1.5. Given that R...

  11. Formation and ordering of epitaxial quantum dots

    Science.gov (United States)

    Atkinson, Paola; Schmidt, Oliver G.; Bremner, Stephen P.; Ritchie, David A.

    2008-10-01

    Single quantum dots (QDs) have great potential as building blocks for quantum information processing devices. However, one of the major difficulties in the fabrication of such devices is the placement of a single dot at a pre-determined position in the device structure, for example, in the centre of a photonic cavity. In this article we review some recent investigations in the site-controlled growth of InAs QDs on GaAs by molecular beam epitaxy. The method we use is ex-situ patterning of the GaAs substrate by electron beam lithography and conventional wet or dry etching techniques to form shallow pits in the surface which then determine the nucleation site of an InAs dot. This method is easily scalable and can be incorporated with marker structures to enable simple post-growth lithographic alignment of devices to each site-controlled dot. We demonstrate good site-control for arrays with up to 10 micron spacing between patterned sites, with no dots nucleating between the sites. We discuss the mechanism and the effect of pattern size, InAs deposition amount and growth conditions on this site-control method. Finally we discuss the photoluminescence from these dots and highlight the remaining challenges for this technique. To cite this article: P. Atkinson et al., C. R. Physique 9 (2008).

  12. CMS Centre at CERN

    CERN Multimedia

    2007-01-01

    A new "CMS Centre" is being established on the CERN Meyrin site by the CMS collaboration. It will be a focal point for communications, where physicists will work together on data quality monitoring, detector calibration, offline analysis of physics events, and CMS computing operations. Construction of the CMS Centre begins in the historic Proton Synchrotron (PS) control room. The historic Proton Synchrotron (PS) control room, Opened by Niels Bohr in 1960, will be reused by CMS to built its control centre. TThe LHC@FNAL Centre, in operation at Fermilab in the US, will work very closely with the CMS Centre, as well as the CERN Control Centre. (Photo Fermilab)The historic Proton Synchrotron (PS) control room is about to start a new life. Opened by Niels Bohr in 1960, the room will be reused by CMS to built its control centre. When finished, it will resemble the CERN Contro...

  13. Quantum dot spectroscopy

    DEFF Research Database (Denmark)

    Leosson, Kristjan

    1999-01-01

    Semiconductor quantum dots ("solid state atoms") are promising candidates for quantum computers and future electronic and optoelectronic devices. Quantum dots are zero-dimensional electronic systems and therefore have discrete energy levels, similar to atoms or molecules. The size distribution...

  14. Client Centred Desing

    DEFF Research Database (Denmark)

    Ørngreen, Rikke; Nielsen, Janni; Levinsen, Karin

    2008-01-01

    In this paper we argue for the use of Client Centred preparation phases when designing complex systems. Through Client Centred Design human computer interaction can extend the focus on end-users to alse encompass the client's needs, context and resources.......In this paper we argue for the use of Client Centred preparation phases when designing complex systems. Through Client Centred Design human computer interaction can extend the focus on end-users to alse encompass the client's needs, context and resources....

  15. Canadian Irradiation Centre

    International Nuclear Information System (INIS)

    The Canadian Irradiation Centre is a non-profit cooperative project between Atomic Energy of Canada Limited, Radiochemical Company and Universite du Quebec, Institut Armand-Frappier, Centre for Applied Research in Food Science. The Centre's objectives are to develop, demonstrate and promote Canada's radiation processing technology and its applications by conducting applied research; training technical, professional and scientific personnel; educating industry and government; demonstrating operational and scientific procedures; developing processing procedures and standards, and performing product and market acceptance trials. This pamphlet outlines the history of radoation technology and the services offered by the Canadian Irradiation Centre

  16. Improved operability of the CANDU 9 control centre

    Energy Technology Data Exchange (ETDEWEB)

    Macbeth, M. J.; Webster, A. [Atomic Energy of Canada Limited, Saskatoon (Canada)

    1996-04-15

    The next generation CANDU nuclear power plant being designed by AECL is the 900 MWe class CANDU 9 station. It is based upon the Darlington CANDU station design which is among the world leaders in capacity factor with low Operation, Maintenance and Administration (OM and A) costs. This Control Centre design includes the proven functionality of existing CANDU control centres (including the Wolsong 2,3, and 4 control centre improvements, such as the Emergency Core Cooling panels), the characteristics identified by systematic design with human factors analysis of operations requirements and the advanced features needed to improve station operability which is made possible by the application of new technology. The CANDU 9 Control Centre provides plant staff with an improved operability capability due to the combination of proveness, systematic design with human factors engineering and enhanced operating features. Significant features which contribute to this improved operability include: {center_dot} Standard NSP, BOP and F/H panels with controls and indicators integrated by a standard display/presentation philosophy. {center_dot} Common plant parameter signal database for extensive monitoring, checking, display and annunciation. {center_dot} Powerful annunciation system allowing alarm filtering, prioritizing and interrogation to enhance staff recognition of events, plant state and required corrective procedural actions. {center_dot} The use of an overview display to present immediate and uncomplicated plant status information to facilitate operator awareness of unit status in a highly readable and recognizable format. {center_dot} Extensive cross checking of similar process parameters amongst themselves, with the counterpart safety system parameters and as well as with 'signature' values obtained from known steady state conditions. {center_dot} Powerful calculation capabilities, using the plant wide database, providing immediate recognizable and readable and

  17. Secondary Uranium Phases of Spent Nuclear Fuel. Coffinite, USiO4, and Studtite, UO4.4H2O. Synthesis, Characterization, and Investigations Regarding Phase Stability

    International Nuclear Information System (INIS)

    The miscibility behavior of the USiO4 - ThSiO4 system was investigated. The end members and ten solid solutions UxTh(1-x)SiO4 with x = 0.12 - 0.92 were successfully synthesized, without formation of other secondary uranium or thorium phases. Lattice parameters of the solid solutions evidently follow Vegard's Law. Investigation of the local structure with EXAFS reveals small differences between U and Th environment attributed to different atomic radii of the metal atoms but no implications for a miscibility gap. The data provided confirms complete miscibility for the system USiO4 - ThSiO4. The structure of the end members was studied in detail with XRD and discussed with special regard to the oxygen positions and the often neglected Si-O bond length. USiO4 could be obtained without UO2 impurities and the lattice parameters derived from Rietveld refinement as c = 6.2606(3) Aa and a = 6.9841(3) Aa. The Si-O distance in USiO4 appears to be 1.64 Aa, which is more reasonable than earlier reported values. Synchrotron X-ray powder diffraction pattern and Raman spectra of synthetic coffinite, USiO4, were obtained for pressures up to 35 GPa and 18 GPa, respectively. From the changes in the diffraction pattern it can be concluded that USiO4 undergoes a first order phase transition from zircon-type (space group I 41/amd) to scheelite-type structure (space group I 41/a) at ∼ 15 GPa and room-temperature. Contrary to earlier reports, the data indicates that this transition is completely reversible upon pressure release. Pressure dependencies of the Raman modes for the zircon structured phase are larger than those reported for hafnon, HfSiO4, and zircon, ZrSiO4, indicating that coffinite, USiO4, is more compressible than these orthosilicates. Bulk moduli fitted from the p-V data for the zircon-type and scheelite-type USiO4 phase are compared to those known to literature for other MSiO4 (M = U, Hf, Zr) compounds. The bulk modulus for zircon-type USiO4 is 180(7) GPa and hence lower than those of ZrSiO4 (205 GPa) as expected from the larger unit cell. The pressure dependence of the Raman modes of USiO4 was studied up to 18 GPa, yet no abrupt changes of peaks or in the peak shifts appear. Furthermore it could be established, that the B1g- and the A1g-modes of the SiO4-4-tetrahedron in the Raman spectrum are very close and overlap at ambient conditions. Structural investigations employing synchrotron X-ray and neutron powder diffraction allowed for a better determination of hydrogen positions in the studtite structure. Through EXAFS measurements the U-O distances of the first coordination sphere and the U-U distance were determined for studtite and metastudtite and compared to those reported in literature and derived from powder diffraction data. While the derived atomic distances reassured the studtite structure and were in good accordance with diffraction data, the spectrum of metastudtite showed an interesting feature in the range of the U-U distance. The structure model from Weck et al. for metastudtite is generally supported by the diffraction data. Through the results derived from NPDF it was possible to amend the model, which ended up in a different atomic position for one uranyl O atom. However, the derived new model seems plausible and encourages further discussion on the topic. Furthermore, this is the first comprehensive synchrotron and neutron powder diffraction study reported on studtite and metastudtite so far. The Raman spectra show no differences in the ν(O-Operoxo)sym stretching mode, implying that this distance is the same in studtite as in metastudtite. From IR spectra it can be observed, that the modes associated to water are strictly confined in metastudtite. The ν(U=O)asym is split in metastudtite, a sign for two different U=O-distances. For studtite the presence of crystal water is observed in the strong ν(OH) mode in the IR spectrum, and confirmed by the observance of the librational modes of water in the IINS spectra. The IINS spectrum of metastudtite completely lacks any features of the lib

  18. Crystal structures of Ca(ClO42·4H2O and Ca(ClO42·6H2O

    Directory of Open Access Journals (Sweden)

    Erik Hennings

    2014-12-01

    Full Text Available The title compounds, calcium perchlorate tetrahydrate and calcium perchlorate hexahydrate, were crystallized at low temperatures according to the solid–liquid phase diagram. The structure of the tetrahydrate consists of one Ca2+ cation eightfold coordinated in a square-antiprismatic fashion by four water molecules and four O atoms of four perchlorate tetrahedra, forming chains parallel to [01-1] by sharing corners of the ClO4 tetrahedra. The structure of the hexahydrate contains two different Ca2+ cations, each coordinated by six water molecules and two O atoms of two perchlorate tetrahedra, forming [Ca(H2O6(ClO4]2 dimers by sharing two ClO4 tetrahedra. The dimers are arranged in sheets parallel (001 and alternate with layers of non-coordinating ClO4 tetrahedra. O—H...O hydrogen bonds between the water molecules as donor and ClO4 tetrahedra and water molecules as acceptor groups lead to the formation of a three-dimensional network in the two structures. Ca(ClO42·6H2O was refined as a two-component inversion twin, with an approximate twin component ratio of 1:1 in each of the two structures.

  19. NaBH4/Na2C2O4/H2O: An efficient System for Selective Reduction of Aldehydes in the presence of Ketones

    Directory of Open Access Journals (Sweden)

    Maghsoud Azimzadeh

    2015-06-01

    Full Text Available Selective reduction of a variety of aldehydes (1 equivalents in the presence of ketones to their corresponding alcohols has been carried out by NaBH4 (1.5 equivalents & Na2C2O4 (3 equivalents in water as green solvent in high to excellent yields of the products. An oxalate-borane complex Na2[(H3B2C2O4] is possibly the active reductant in the reaction mixture. Also, Chemoselective, regioselectivity and exclusive 1,2-reduction enals to their corresponding allylic alcohols in high to excellent yields was achieved successfully with this reducing system.

  20. Synthesis of calcium diborate CaO·B2O3·4H2O (Ca 114) containing definite boron isotope

    International Nuclear Information System (INIS)

    A new method for the synthesis of calcium diborate in aqueous solutions from calcium oxide, sodium hydroxide and boric acid containing a definite boron isotope (10B or 11B) has been elaborated. Since the mother liquid can be utilized for repeated synthesis, the yield of the diborate with respect to boron is higher than in other processes

  1. Fourier transform-infrared studies of thin H2SO4/H2O films: Formation, water uptake, and solid-liquid phase changes

    Science.gov (United States)

    Middlebrook, Ann M.; Iraci, Laura T.; Mcneill, Laurie S.; Koehler, Birgit G.; Wilson, Margaret A.; Saastad, Ole W.; Tolbert, Margaret A.; Hanson, David R.

    1993-01-01

    Fourier transform-infrared (FTIR) spectroscopy was used to examine films representative of stratospheric sulfuric acid aerosols. Thin films of sulfuric acid were formed in situ by the condensed phase reaction of SO3 with H2O. FTIR spectra show that the sulfuric acid films absorb water while cooling in the presence of water vapor. Using stratospheric water pressures, the most dilute solutions observed were greater than 40 wt % before simultaneous ice formation and sulfuric acid freezing occurred. FTIR spectra also revealed that the sulfuric acid films crystallized mainly as sulfuric acid tetrahydrate (SAT). Crystallization occurred either when the composition was about 60 wt% H2SO4 or after ice formed on the films at temperatures 1-4 K below the ice frost point. Finally, we determined that the melting point for SAT depended on the background water pressure and was 216-219 K in the presence of 4 x 10(exp -4) Torr H2O. Our results suggest that once frozen, sulfuric acid aerosols in the stratosphere are likely to melt at these temperatures, 30 K colder than previously thought.

  2. Frequency Comb Spectroscopy of CO(2), CH(4), H(2)O, and Isotopes Over a 2 km Outdoor Path: Concentration Retrievals Using Different Absorption Models

    Science.gov (United States)

    Rieker, G. B.; Giorgetta, F. R.; Coddington, I.; Swann, W. C.; Zolot, A. M.; Sinclair, L. C.; Baumann, E.; Cromer, C.; Newbury, N.

    2014-06-01

    A dual frequency comb spectrometer is used to make high signal-to-noise measurements of atmospheric absorption from 5990 to 6260 cm-1 with 0.0033 cm-1 point spacing and ˜4·10-8 cm-1 resolution over a 2 km outdoor air path. The spectra, which encompass over 700 absorption features of CO2, CH4, and H2O, are fit with several absorption models to assess the quality of the models and to retrieve the various species concentrations and air temperature. The models tested include the HITRAN 2008 and 2012 spectral databases with Voigt line-shape profiles as well as a recent model for CO2 that includes the effects of line mixing and speed dependence. Residuals are typically less than 2% of the peak absorbance, except for the HITRAN 2012 CH4 model, which exhibits larger residuals. Species concentration retrievals using the models are compared with a calibrated point sensor mounted on a tower near the open air path.

  3. The IAGOS-core greenhouse gas package : a measurement system for continuous airborne observations of CO2, CH4, H2O and CO

    NARCIS (Netherlands)

    Filges, Annette; Gerbig, Christoph; Chen, Huilin; Franke, Harald; Klaus, Christoph; Jordan, Armin

    2015-01-01

    Within the framework of IAGOS-ERI (In-service Aircraft for a Global Observing System - European Research Infrastructure), a cavity ring-down spectroscopy (CRDS)-based measurement system for the autonomous measurement of the greenhouse gases (GHGs) CO2 and CH4, as well as CO and water vapour was desi

  4. The IGU Knowledge Centre

    NARCIS (Netherlands)

    Huizing, Bernardus

    2005-01-01

    This article describes an innovative service for members of the International Gas Union - IGU. The IGU Knowledge Centre provides members with relevant information and data. In this article is described why, how and where.

  5. CENTRE FOR GEOMETRICAL METROLOGY

    DEFF Research Database (Denmark)

    De Chiffre, Leonardo

    The objective of this Annual Report is to give a general introduction to CGM as well as to give an account of the tasks carried out using the facilities of CGM's Instrument Centre during 1998 and 1999....

  6. Virtual particle therapy centre

    CERN Multimedia

    2015-01-01

    Particle therapy is an advanced technique of cancer radiation therapy, using protons or other ions to target the cancerous mass. This advanced technique requires a multi-disciplinary team working in a specialised centre. 3D animation: Nymus3D

  7. The Bruce Energy Centre

    International Nuclear Information System (INIS)

    The Bruce Energy Centre Development Corporation is a joint venture of the Ontario Energy Corporation and 6 private companies formed to market surplus steam from the Bruce Nuclear Power Development. The corporation will also sell or lease land near Bruce NPD. The Bruce Energy Centre has an energy output of 900 BTU per day per dollar invested. Potential customers include greenhouse operators, aquaculturalists, food and beverage manufacturers, and traditional manufacturers

  8. The ideal Atomic Centre

    International Nuclear Information System (INIS)

    The author presents considerations which should prove to be of interest to all those who have to design, to construct and to operate a nuclear research centre. A large number of the ideas presented can also be applied to non-nuclear scientific research centres. In his report the author reviews: various problems with which the constructor is faced: ground-plan, infrastructure, buildings and the large units of scientific equipment in the centre, and those problems facing the director: maintenance, production, supplies, security. The author stresses the relationship which ought to exist between the research workers and the management. With this aim in view he proposes the creation of National School for Administration in Research which would train administrative executives for public or private organisations; they would be specialised in the fields of fundamental or applied research. (author)

  9. Lidar Calibration Centre

    Science.gov (United States)

    Pappalardo, Gelsomina; Freudenthaler, Volker; Nicolae, Doina; Mona, Lucia; Belegante, Livio; D'Amico, Giuseppe

    2016-06-01

    This paper presents the newly established Lidar Calibration Centre, a distributed infrastructure in Europe, whose goal is to offer services for complete characterization and calibration of lidars and ceilometers. Mobile reference lidars, laboratories for testing and characterization of optics and electronics, facilities for inspection and debugging of instruments, as well as for training in good practices are open to users from the scientific community, operational services and private sector. The Lidar Calibration Centre offers support for trans-national access through the EC HORIZON2020 project ACTRIS-2.

  10. Quantum dot spectroscopy

    DEFF Research Database (Denmark)

    Leosson, Kristjan

    Semiconductor quantum dots ("solid-state atoms") are promising candidates for quantum computers and future electronic and optoelectronic devices. Quantum dots are zero-dimensional electronic systems and therefore have discrete energy levels, similar to atoms or molecules. The size distribution...

  11. Quantum Dots: Theory

    Energy Technology Data Exchange (ETDEWEB)

    Vukmirovic, Nenad; Wang, Lin-Wang

    2009-11-10

    This review covers the description of the methodologies typically used for the calculation of the electronic structure of self-assembled and colloidal quantum dots. These are illustrated by the results of their application to a selected set of physical effects in quantum dots.

  12. Ultrasmall silicon quantum dots

    NARCIS (Netherlands)

    Zwanenburg, F.A.; Van Loon, A.A.; Steele, G.A.; Rijmenam, C.E.W.M.; Balder, T.; Fang, Y.; Lieber, C.M.; Kouwenhoven, L.P.

    2009-01-01

    We report the realization of extremely small single quantum dots in p-type silicon nanowires, defined by Schottky tunnel barriers with Ni and NiSi contacts. Despite their ultrasmall size the NiSi–Si–NiSi nanowire quantum dots readily allow spectroscopy of at least ten consecutive holes, and addition

  13. International research centre launched

    International Nuclear Information System (INIS)

    Full text: The first scientific research and educational institution to be set up on a completely international basis was officially inaugurated in Trieste on 5 October 1964 by the Director General of IAEA, Dr. Sigvard Eklund, when he opened the first seminar of the International Centre for Theoretical Physics. As evidence of the international nature of the institution he noted that the scientists who would work and teach there during the first year represented sixteen different countries. By the end of 1964, the Centre building was nearing completion and three of the five floors were occupied. A successful symposium had been held on the subject of plasma physics, and a score of professors and fellows were at work, from Bulgaria, Czechoslovakia, Greece, India, Japan, Jordan, the Netherlands, Norway, Pakistan, Poland, the United Kingdom, and the United States. A dozen scientific papers had been issued as preprints. The main purpose of the Centre is to foster the advancement of theoretical physics through training and research; at first the chief subject will be high-energy and elementary particle physics. Plasma physics, low energy physics and solid-state physics will also be dealt with. Special attention is paid to the needs of the developing countries. Of the 25 fellows selected for the academic year 1964-65, more than half are from South America, Africa and Asia. In conjunction with the Research Centre, there is an Advanced School for theoretical Physics to provide graduate training for fellows who need such preparation before they embark upon research. The Centre works under the guidance of a Scientific Council comprising the president, Prof. M. Sandoval-Vallarta (Nuclear Energy Commission of Mexico); Prof. A. Abragam (Saclay, France); Prof. R. Oppenheimer (Institute for Advanced Study, Princeton, USA); Dr. V. Soloviev (Dubna, USSR); Prof V.F. Weiskopf (Director General, CERN) ; Prof Abdus Salam (Imperial College, London) ; Prof. P. Budini (University of Trieste

  14. Quantum dot density studies for quantum dot intermediate band solar cells

    Energy Technology Data Exchange (ETDEWEB)

    Thomassen, Sedsel Fretheim; Zhou, Dayong; Vitelli, Stefano; Mayani, Maryam Gholami; Fimland, Bjoern-Ove; Reenaas, Turid Worren

    2010-07-01

    Quantum dots (QDs) have been an active area of research for many years and have been implemented in several applications, such as lasers and detectors. During the last years, some attempts have been made to increase the absorption and efficiency of solar cells by inserting QDs into the intrinsic region of pin solar cells. So far, these attempts have been successful in increasing the absorption, but not the cell efficiency. There are probably several reasons for this lack of efficiency increase, but we believe that one important reason is the low density of the implemented QDs. In this work, samples of single layer InAs QDs on n-GaAs(001) substrates have been grown by molecular beam epitaxy (MBE) and we have performed a systematic study of how deposition parameters affect the QD density. The aim is to achieve densities > 1011 cm-2. The nominal substrate temperature (360 - 500 deg. C), the InAs growth rate (0.085 - 1 ML/s) and thickness (2.0 - 2.8 ML) have been varied in a systematic way for two different deposition methods of InAs, i.e. continuous deposition or deposition with interruptions. In addition, we have for the continuous growth samples also varied the As-flux (0.5 - 6 centre dot10-6 torr). Scanning electron microscopy (SEM) has been the main characterization method to determine quantum dot sizes and densities, and atomic force microscopy (AFM) has been used for evaluation of the quantum dot heights. We find that the QD density increases with reduced growth temperature and that it is higher for samples grown continuously than for samples grown with growth interruptions. The homogeneity is also strongly affected by temperature, InAs deposition method and the As-flux. We have observed QD densities as high as 2.5 centre dot1011 cm-2 for the samples grown at the lowest growth temperatures. (Author)

  15. Academic Drug Discovery Centres

    DEFF Research Database (Denmark)

    Kirkegaard, Henriette Schultz; Valentin, Finn

    2014-01-01

    Academic drug discovery centres (ADDCs) are seen as one of the solutions to fill the innovation gap in early drug discovery, which has proven challenging for previous organisational models. Prior studies of ADDCs have identified the need to analyse them from the angle of their economic...

  16. Implementing Responsibility Centre Budgeting

    Science.gov (United States)

    Vonasek, Joseph

    2011-01-01

    Recently, institutes of higher education (universities) have shown a renewed interest in organisational structures and operating methodologies that generate productivity and innovation; responsibility centre budgeting (RCB) is one such process. This paper describes the underlying principles constituting RCB, its origin and structural elements, and…

  17. ATLAS Visitors Centre

    CERN Multimedia

    claudia Marcelloni

    2009-01-01

    ATLAS Visitors Centre has opened its shiny new doors to the public. Officially launched on Monday February 23rd, 2009, the permanent exhibition at Point 1 was conceived as a tour resource for ATLAS guides, and as a way to preserve the public’s opportunity to get a close-up look at the experiment in action when the cavern is sealed.

  18. Elderly Care Centre

    Science.gov (United States)

    Wagiman, Aliani; Haja Bava Mohidin, Hazrina; Ismail, Alice Sabrina

    2016-02-01

    The demand for elderly centre has increased tremendously abreast with the world demographic change as the number of senior citizens rose in the 21st century. This has become one of the most crucial problems of today's era. As the world progress into modernity, more and more people are occupied with daily work causing the senior citizens to lose the care that they actually need. This paper seeks to elucidate the best possible design of an elderly care centre with new approach in order to provide the best service for them by analysing their needs and suitable activities that could elevate their quality of life. All these findings will then be incorporated into design solutions so as to enhance the living environment for the elderly especially in Malaysian context.

  19. Controllable synthesis of cadmium sulfide quantum dots(QDs)and its photoluminescence property%硫化镉量子点的可控制备及荧光性能研究

    Institute of Scientific and Technical Information of China (English)

    佘厚德; 康燕; 万新磊; 魏娟娟

    2014-01-01

    采用溶剂热法,以 Cd(NO3)2·4H 2 O 和升华硫为镉、硫来源,油胺为反应溶剂和表面活性剂,制备了硫化镉量子点(CdS QDs),并研究了反应温度、反应时间对硫化镉量子点尺寸的影响。通过 X 射线衍射(XRD)和透射电镜(TEM)对所制备产物的结构和形貌进行了表征。结果表明,所制备的硫化镉量子点结晶度较高,单分散性好,尺寸均一。通过紫外可见吸收光谱(UV-Vis)和荧光光谱(PL)表征了硫化镉量子点随反应温度和时间的变化,结果发现,随反应温度的升高和反应时间的延长,其吸收峰出现了明显的红移,即通过控制反应温度和时间可以控制硫化镉量子点的尺寸和发光颜色。%Cadmium sulfide quantum dots (CdS QDs ) are synthesized via solvothermal method using Cd(NO3 )2·4H 2 O and sulfur as the precursors and oleylamine as solvent and surfactant.The influnces of the temperature as well as the reaction time on the size of the QDs are also investigated.The crystalline structure and morphology of the products are characterized by powder X-ray diffraction (XRD ) and transmission electron microscopy (TEM).The results show that the as-synthesized CdS QDs possess the properties of high crystallinity,monodispersity,as well as uniform size.The variation of size of CdS QDs with the change of the reaction temperature and the reaction times is investigated by ultraviolet-visible spectrum (UV-Vis)and the photoluminescence (PL)spectrum.The results show that with the increasing of the temperature and the prolongation of the reaction time, the obvious red-shift is observed. It suggests that the size of quantum dots can be adjusted by changing of reaction temperature and reaction time.

  20. Graphene quantum dots

    CERN Document Server

    Güçlü, Alev Devrim; Korkusinski, Marek; Hawrylak, Pawel

    2014-01-01

    This book reflects the current status of theoretical and experimental research of graphene based nanostructures, in particular quantum dots, at a level accessible to young researchers, graduate students, experimentalists and theorists. It presents the current state of research of graphene quantum dots, a single or few monolayer thick islands of graphene. It introduces the reader to the electronic and optical properties of graphite, intercalated graphite and graphene, including Dirac fermions, Berry's phase associated with sublattices and valley degeneracy, covers single particle properties of

  1. Tele-centres in Ghana

    DEFF Research Database (Denmark)

    Falch, Morten

    2004-01-01

    Tele-centres offer a low cost opportunity for the many who cannot afford their own phone or Internet connection. This paper presents a field study of tele-centres in Ghana and analyses how they contribute to universal access.......Tele-centres offer a low cost opportunity for the many who cannot afford their own phone or Internet connection. This paper presents a field study of tele-centres in Ghana and analyses how they contribute to universal access....

  2. Treatment Outcomes of Patients Placed on Treatment Under Directly Observed Therapy Short-Course (Dots)

    OpenAIRE

    Kaur Gurpreet; Goel N; Kumar Dinesh; Janmeja A; Swami H; Kalia Meenu

    2008-01-01

    Background : Tuberculosis continues to be a pressing health problem in India. The Revised National Tuberculosis Programme (RNTCP), an application of Directly Observed Treatment Short-course (DOTS) in India, launched in 1997 needs contin-uous evaluation. Objective : To study the outcomes of treatment among the patients put on DOTS under RNTCP in Chandigarh, UT. Material & Methods : A Longitudi-nal study was conducted during 2004-2005 in 13 Microscopic centres (MC′s) spread over...

  3. Binding Energies of Negatively Charged Donors in a Gaussian Potential Quantum Dot

    Institute of Scientific and Technical Information of China (English)

    XIE Wen-Fang

    2005-01-01

    @@ We investigate a negatively charged donor centre (D-) trapped by a quantum dot, which is subjected to a Gaussian potential confinement. Calculations are carried out by using the method of numerical diagonalization of Hamiltonian within the effective-mass approximation. The dependence of the ground state of the negatively charged donor on the dot size and the potential depth is studied. The same calculations performed with the parabolic approximation of the Gaussian potential lead to the results that are qualitatively and quantitatively different.

  4. Transition energies and magnetic properties of a neutral donor complex in a Gaussian GaAs quantum dot

    Science.gov (United States)

    Boda, Aalu; Chatterjee, Ashok

    2016-09-01

    The problem of a neutral hydrogenic donor (D0) centre located at the centre of a GaAs quantum dot with Gaussian confinement is studied in the presence of an external magnetic field. The ground and the first excited state energies and the corresponding binding energies are obtained as functions of the potential strength, quantum dot radius and the magnetic field using a variational method. It is suggested that the first excited state of the D0 centre is bound for sufficiently strong confinement potential. The 1 s - 2p- transition energy and the magnetic susceptibilities for the ground and the first excited states are also determined.

  5. DGNB certified Healthcare Centres

    DEFF Research Database (Denmark)

    Brunsgaard, Camilla; Larsen, Tine Steen

    2015-01-01

    for sustainability and wants a certification. This research investigates the decision‐making and design process (DMaDP) behind four DGNB certified Healthcare Centres (HCC) in Northern Jutland in Denmark. In general, knowledge about the DMaDP is important. However it is important to know what part DGNB plays...... a dialog about DGNB and energy concept is important even before anyone start sketching. Experiences with the different approaches will be further outlined in the paper.Future research has the intention to collect further knowledge about DGNB and DMaDP in practise. This project was limited to Healthcare...

  6. Centre liikekeskuksen digital signage

    OpenAIRE

    Bincl, Suzana

    2015-01-01

    Opinnäytetyöni tarkastelee digital signagen suunnittelussa huomioitavia tekijöitä ja sen arvoa markkinointikanavana. Työ on toteutettu tilaustyönä Lappeenrantalaiselle mainostoimisto Mediakolmiolle. Työ sisältää teoriaosuuden lisäksi sisältösuunnitelman rakenteilla olevalle Centre liikekeskukselle. Tavoitteena oli luoda liikekeskukselle sen brändiä tukeva digital signage konsepti. Työ ei sisällä valmista tuotetta, vaan se toimii ehdotelmana myöhemmin alkavalle tuotanno...

  7. Town Centre Redevelopment Strategies

    DEFF Research Database (Denmark)

    Vagnby, Bo Hellisen

    urban planning and design strategieswhich have been practised in most of the larger Danish towns: pedestrian streets, shopping centres, preservation of historic features, waterfronts, concentration of offices, conference and sports facilities, improvement og traffic and transport conditions as well...... as slum clearence and urban renewal. To a certain extent parallels are drawn to international experiences, especially where these are of such a nature that they can be assumed transferred to Danish connctions. Conclusively, the strategies are discussed in the light of the turn of Danish urban planning...

  8. A novel POSS-coated quantum dot for biological application

    OpenAIRE

    Rizvi SB; Yildirimer L; Ghaderi S; Ramesh B; Seifalian AM; Keshtgar M

    2012-01-01

    Sarwat B Rizvi,1 Lara Yildirimer,1 Shirin Ghaderi,1 Bala Ramesh,1 Alexander M Seifalian,1,2 Mo Keshtgar1,21UCL Centre for Nanotechnology and Regenerative Medicine, Division of Surgery and Interventional Science, University College London, United Kingdom; 2Royal Free Hampstead NHS Trust Hospital, London, United KingdomAbstract: Quantum dots (QDs) are fluorescent semiconductor nanocrystals that have the potential for major advancements in the field of nanomedicine through their unique photophys...

  9. [The primary healthcare centres].

    Science.gov (United States)

    Brambilla, Antonio; Maciocco, Gavino

    2014-04-01

    The central attributes of primary care are: first contact (accessibility), longitudinality (person- focused preventive and curative care overtime), patient-oriented comprehensiveness and coordination (including navigation towards secondary and tertiary care). Besides taking care of the needs of the individuals, primary health care teams are also looking at the community, especially when addressing social determinants of health. The rationale for the benefits for primary care for health has been found in: 1) greater access to needed services; 2) better quality of care; 3) a greater focus on prevention; 4) early management of health problems; 5) organizing and delivering high quality care for chronic non-communicable diseases. This paper describes the role of primary healthcare centres in strengthening community primary services and in reducing health inequalities. Furthemore, the experiences of Regional Health Services from Tuscany and Emilia-Romagna are discussed, with a brief overview of the literature. PMID:24770539

  10. Quantum dot solar cells

    CERN Document Server

    Wu, Jiang

    2013-01-01

    The third generation of solar cells includes those based on semiconductor quantum dots. This sophisticated technology applies nanotechnology and quantum mechanics theory to enhance the performance of ordinary solar cells. Although a practical application of quantum dot solar cells has yet to be achieved, a large number of theoretical calculations and experimental studies have confirmed the potential for meeting the requirement for ultra-high conversion efficiency. In this book, high-profile scientists have contributed tutorial chapters that outline the methods used in and the results of variou

  11. Experiences of Telebased Information Centres

    DEFF Research Database (Denmark)

    Falch, Morten

    1999-01-01

    Tele-based information community centres or just tele-centres have been seen as the killer application to empower local communities in developed and developing countries to meet the challenges of the information society. This paper will present a number of models for introducing such centres and ...... and discuss the different models and national strategies used for setting up tele-based information in relation to the Ghana experience.......Tele-based information community centres or just tele-centres have been seen as the killer application to empower local communities in developed and developing countries to meet the challenges of the information society. This paper will present a number of models for introducing such centres...

  12. Update on System Coordination Centre

    Energy Technology Data Exchange (ETDEWEB)

    Stangl, W. [Power Pool of Alberta, Calgary, AB (Canada)

    1998-07-01

    The new System Coordination Centre at the Power Pool of Alberta was designed to meet the unique requirements of Alberta`s electric industry under the new regulatory regime. Development of the Centre, key provisions of the energy management system (EMS) are highlighted. The centre will provide an energy management system for the Pool`s system controller function and interface with the Power Pool Administrator`s market functions and the operations of the Transmission Administrator. System controllers are expected to be operating from the new location by the end of 1998. Unique EMS features of the centre include: (1) real-time management of energy market and network operations using diverse SCADA/EMS, (2) inter-control centre protocol used to accommodate the unique participant information requirements, and (3) special custom applications. The Centre is expected to be fully functioning by July 1999. 1 fig.

  13. Carbon nanotube quantum dots

    NARCIS (Netherlands)

    Sapmaz, S.

    2006-01-01

    Low temperature electron transport measurements on individual single wall carbon nanotubes are described in this thesis. Carbon nanotubes are small hollow cylinders made entirely out of carbon atoms. At low temperatures (below ~10 K) finite length nanotubes form quantum dots. Because of its small si

  14. Colloidal Double Quantum Dots.

    Science.gov (United States)

    Teitelboim, Ayelet; Meir, Noga; Kazes, Miri; Oron, Dan

    2016-05-17

    Pairs of coupled quantum dots with controlled coupling between the two potential wells serve as an extremely rich system, exhibiting a plethora of optical phenomena that do not exist in each of the isolated constituent dots. Over the past decade, coupled quantum systems have been under extensive study in the context of epitaxially grown quantum dots (QDs), but only a handful of examples have been reported with colloidal QDs. This is mostly due to the difficulties in controllably growing nanoparticles that encapsulate within them two dots separated by an energetic barrier via colloidal synthesis methods. Recent advances in colloidal synthesis methods have enabled the first clear demonstrations of colloidal double quantum dots and allowed for the first exploratory studies into their optical properties. Nevertheless, colloidal double QDs can offer an extended level of structural manipulation that allows not only for a broader range of materials to be used as compared with epitaxially grown counterparts but also for more complex control over the coupling mechanisms and coupling strength between two spatially separated quantum dots. The photophysics of these nanostructures is governed by the balance between two coupling mechanisms. The first is via dipole-dipole interactions between the two constituent components, leading to energy transfer between them. The second is associated with overlap of excited carrier wave functions, leading to charge transfer and multicarrier interactions between the two components. The magnitude of the coupling between the two subcomponents is determined by the detailed potential landscape within the nanocrystals (NCs). One of the hallmarks of double QDs is the observation of dual-color emission from a single nanoparticle, which allows for detailed spectroscopy of their properties down to the single particle level. Furthermore, rational design of the two coupled subsystems enables one to tune the emission statistics from single photon

  15. Electron correlations in quantum dots

    CERN Document Server

    Tipton, D L J

    2001-01-01

    Quantum dot structures confine electrons in a small region of space. Some properties of semiconductor quantum dots, such as the discrete energy levels and shell filling effects visible in addition spectra, have analogies to those of atoms and indeed dots are sometimes referred to as 'artificial atoms'. However, atoms and dots show some fundamental differences due to electron correlations. For real atoms, the kinetic energy of electrons dominates over their mutual Coulomb repulsion energy and for this reason the independent electron approximation works well. For quantum dots the confining potential may be shallower than that of real atoms leading to lower electron densities and a dominance of mutual Coulomb repulsion over kinetic energy. In this strongly correlated regime the independent electron picture leads to qualitatively incorrect results. This thesis concentrates on few-electron quantum dots in the strongly correlated regime both for quasi-one-dimensional and two-dimensional dots in a square confining p...

  16. Fuzzy Dot Structure of BG-algebras

    OpenAIRE

    Tapan Senapati; Monoranjan Bhowmik; Madhumangal Pal

    2014-01-01

    In this paper, the notions of fuzzy dot subalgebras is introduced together with fuzzy normal dot subalgebras and fuzzy dot ideals of BG-algebras. The homomorphic image and inverse image are investigated in fuzzy dot subalgebras and fuzzy dot ideals of BG-algebras. Also, the notion of fuzzy relations on the family of fuzzy dot subalgebras and fuzzy dot ideals of BG-algebras are introduced with some related properties.

  17. Council celebrates CERN Control Centre

    CERN Multimedia

    2006-01-01

    With the unveiling of its new sign, the CERN Control Centre was officially inaugurated on Thursday 16 March. To celebrate its startup, CERN Council members visited the sleek centre, a futuristic-looking room filled with a multitude of monitoring screens.

  18. Quantum Dot Sensitized Photoelectrodes

    OpenAIRE

    Thomas Nann; Thomas J. Macdonald

    2011-01-01

    Quantum Dots (QDs) are promising alternatives to organic dyes as sensitisers for photocatalytic electrodes. This review article provides an overview of the current state of the art in this area. More specifically, different types of QDs with a special focus on heavy-metal free QDs and the methods for preparation and adsorption onto metal oxide electrodes (especially titania and zinc oxide) are discussed. Eventually, the key areas of necessary improvements are identified and assessed.

  19. Quantum Dot Sensitized Photoelectrodes

    Directory of Open Access Journals (Sweden)

    Thomas Nann

    2011-11-01

    Full Text Available Quantum Dots (QDs are promising alternatives to organic dyes as sensitisers for photocatalytic electrodes. This review article provides an overview of the current state of the art in this area. More specifically, different types of QDs with a special focus on heavy-metal free QDs and the methods for preparation and adsorption onto metal oxide electrodes (especially titania and zinc oxide are discussed. Eventually, the key areas of necessary improvements are identified and assessed.

  20. Plasmonic fluorescent quantum dots

    OpenAIRE

    Jin, Yongdong; Gao, Xiaohu

    2009-01-01

    Combining multiple discrete components into a single multifunctional nanoparticle could be useful in a variety of applications. Retaining the unique optical and electrical properties of each component after nanoscale integration is, however, a long-standing problem1,2. It is particularly difficult when trying to combine fluorophores such as semiconductor quantum dots with plasmonic materials such as gold, because gold and other metals can quench the fluorescence3,4. So far, the combination of...

  1. Nanocrystal quantum dots

    CERN Document Server

    Klimov, Victor I

    2010-01-01

    ""Soft"" Chemical Synthesis and Manipulation of Semiconductor Nanocrystals, J.A. Hollingsworth and V.I. Klimov Electronic Structure in Semiconductor Nanocrystals: Optical Experiment, D.J. NorrisFine Structure and Polarization Properties of Band-Edge Excitons in Semiconductor Nanocrystals, A.L. EfrosIntraband Spectroscopy and Dynamics of Colloidal Semiconductor Quantum Dots, P. Guyot-Sionnest, M. Shim, and C. WangMultiexciton Phenomena in Semiconductor Nanocrystals, V.I. KlimovOptical Dynamics in Single Semiconductor Quantum Do

  2. Quantum dot nanostructures

    Directory of Open Access Journals (Sweden)

    Mohamed Henini

    2002-06-01

    These sophisticated technologies for the growth of high quality epitaxial layers of compound semiconductor materials on single crystal semiconductor substrates are becoming increasingly important for the development of the semiconductor electronics industry. This article is intended to convey the flavor of the subject by focusing on the technology and applications of self-assembled quantum dots (QDs and to give an introduction to some of the essential characteristics.

  3. The Aube centre; Le Centre de l`Aube

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1996-07-01

    This educational booklet is devoted to a general presentation of the Aube radioactive wastes storage centre. After a short presentation of the Andra, the French national agency for the management of radioactive wastes, it gives some general information about radioactive wastes (origin, classification), containers (quality assurance and different types), wastes transportation (planning, safety), and about the Aube centre itself: description, treatment and conditioning of drums (compacting and injection), storage facilities, geological situation of the site, and environmental controls. (J.S.)

  4. Contemporary design for 'landmark' centre.

    Science.gov (United States)

    2009-08-01

    As one of the UK's largest builders of healthcare facilities, construction company Morgan Ashurst is accustomed to delivering complex, challenging hospital projects. The construction of a new oncology centre at Musgrove Park Hospital, Taunton for Taunton and Somerset NHS Foundation Trust-- said to be the first new stand-alone radiotherapy centre to be built in the UK for almost 20 years--was no exception. Health Estate Journal reports. PMID:19711668

  5. The centre of the action

    CERN Document Server

    2008-01-01

    The CERN Control Centre (CCC) has all the ingredients of an action movie control room: hundreds of screens, technicians buzzing in and out, huge floor-to-ceiling windows revealing the looming vista of a mountain range, flashing lights, microphones… This is the place where not just the LHC, but the whole of CERN’s accelerator complex and technical support is based - truly the centre of the action at CERN.

  6. Inter-dot coupling effects on transport through correlated parallel coupled quantum dots

    Indian Academy of Sciences (India)

    Shyam Chand; G Rajput; K C Sharma; P K Ahluwalia

    2009-05-01

    Transport through symmetric parallel coupled quantum dot system has been studied, using non-equilibrium Green function formalism. The inter-dot tunnelling with on-dot and inter-dot Coulomb repulsion is included. The transmission coefficient and Landaur–Buttiker like current formula are shown in terms of internal states of quantum dots. The effect of inter-dot tunnelling on transport properties has been explored. Results, in intermediate inter-dot coupling regime show signatures of merger of two dots to form a single composite dot and in strong coupling regime the behaviour of the system resembles the two decoupled dots.

  7. Training centres - organization and management

    International Nuclear Information System (INIS)

    In the lecture 'Training centres - organization and management' some principles and requirements which influence the organization, management and activity pattern of nuclear training centres, are briefly introduced. It is demonstrated, step by step, how these general principles are implemented in the development of the Czechoslovak nuclear power programme, it means, how the training of the NPP personnel proceeds in Czechoslovak nuclear training centres. General principles which are selected: a connection between the capacity of the training centre and the scope and needs of the nuclear power programme, a position of the training center within the institutional set-up, a structure and organization of the training system which complies with the system of NPP construction, reflect the pattern and the activity of the nuclear training centre and nuclear power technical level, a research group of workers in the nuclear training centre, main tasks and technical facilities, management of the training process and a transfer of knowledge and research results into the training process. The lecture is supplemented by pictures and slides. (orig.)

  8. Water-soluble multidentate polymers compactly coating Ag2S quantum dots with minimized hydrodynamic size and bright emission tunable from red to second near-infrared region

    Science.gov (United States)

    Gui, Rijun; Wan, Ajun; Liu, Xifeng; Yuan, Wen; Jin, Hui

    2014-04-01

    Hydrodynamic size-minimized quantum dots (QDs) have outstanding physicochemical properties for applications in multicolor molecular and cellular imaging at the level of single molecules and nanoparticles. In this study, we have reported the aqueous synthesis of Ag2S QDs by using thiol-based multidentate polymers as capping reagents. By regulating the composition of the precursors (AgNO3 and sulfur-N2H4.H2O complex) and multidentate polymers (poly(acrylic acid)-graft-cysteamine-graft-ethylenediamine), as well as the reaction time, Ag2S QDs (2.6-3.7 nm) are prepared, displaying tunable photoluminescence (PL) emission from red to the second near-infrared region (687-1096 nm). The small hydrodynamic thickness (1.6-1.9 nm) of the multidentate polymers yields a highly compact coating for the QDs, which results in the bright fluorescent QDs with high PL quantum yields (QYs: 14.2-16.4%). Experimental results confirm that the QDs have high PL stability and ultralow cytotoxicity, as well as high PLQYs and small hydrodynamic sizes (4.5-5.6 nm) similar to fluorescent proteins (27-30 kDa), indicating the feasibility of highly effective PL imaging in cells and living animals.Hydrodynamic size-minimized quantum dots (QDs) have outstanding physicochemical properties for applications in multicolor molecular and cellular imaging at the level of single molecules and nanoparticles. In this study, we have reported the aqueous synthesis of Ag2S QDs by using thiol-based multidentate polymers as capping reagents. By regulating the composition of the precursors (AgNO3 and sulfur-N2H4.H2O complex) and multidentate polymers (poly(acrylic acid)-graft-cysteamine-graft-ethylenediamine), as well as the reaction time, Ag2S QDs (2.6-3.7 nm) are prepared, displaying tunable photoluminescence (PL) emission from red to the second near-infrared region (687-1096 nm). The small hydrodynamic thickness (1.6-1.9 nm) of the multidentate polymers yields a highly compact coating for the QDs, which results in

  9. Perceptual strategies of pigeons to detect a rotational centre--a hint for star compass learning?

    Science.gov (United States)

    Alert, Bianca; Michalik, Andreas; Helduser, Sascha; Mouritsen, Henrik; Güntürkün, Onur

    2015-01-01

    Birds can rely on a variety of cues for orientation during migration and homing. Celestial rotation provides the key information for the development of a functioning star and/or sun compass. This celestial compass seems to be the primary reference for calibrating the other orientation systems including the magnetic compass. Thus, detection of the celestial rotational axis is crucial for bird orientation. Here, we use operant conditioning to demonstrate that homing pigeons can principally learn to detect a rotational centre in a rotating dot pattern and we examine their behavioural response strategies in a series of experiments. Initially, most pigeons applied a strategy based on local stimulus information such as movement characteristics of single dots. One pigeon seemed to immediately ignore eccentric stationary dots. After special training, all pigeons could shift their attention to more global cues, which implies that pigeons can learn the concept of a rotational axis. In our experiments, the ability to precisely locate the rotational centre was strongly dependent on the rotational velocity of the dot pattern and it crashed at velocities that were still much faster than natural celestial rotation. We therefore suggest that the axis of the very slow, natural, celestial rotation could be perceived by birds through the movement itself, but that a time-delayed pattern comparison should also be considered as a very likely alternative strategy.

  10. Perceptual strategies of pigeons to detect a rotational centre--a hint for star compass learning?

    Directory of Open Access Journals (Sweden)

    Bianca Alert

    Full Text Available Birds can rely on a variety of cues for orientation during migration and homing. Celestial rotation provides the key information for the development of a functioning star and/or sun compass. This celestial compass seems to be the primary reference for calibrating the other orientation systems including the magnetic compass. Thus, detection of the celestial rotational axis is crucial for bird orientation. Here, we use operant conditioning to demonstrate that homing pigeons can principally learn to detect a rotational centre in a rotating dot pattern and we examine their behavioural response strategies in a series of experiments. Initially, most pigeons applied a strategy based on local stimulus information such as movement characteristics of single dots. One pigeon seemed to immediately ignore eccentric stationary dots. After special training, all pigeons could shift their attention to more global cues, which implies that pigeons can learn the concept of a rotational axis. In our experiments, the ability to precisely locate the rotational centre was strongly dependent on the rotational velocity of the dot pattern and it crashed at velocities that were still much faster than natural celestial rotation. We therefore suggest that the axis of the very slow, natural, celestial rotation could be perceived by birds through the movement itself, but that a time-delayed pattern comparison should also be considered as a very likely alternative strategy.

  11. Interfacial effects of the Cu2O nano-dots decorated Co3O4 nanorods array and its photocatalytic activity for cleaving organic molecules

    Science.gov (United States)

    Qiu, X. P.; Yu, J. S.; Xu, H. M.; Chen, W. X.; Hu, W.; Chen, G. L.

    2016-09-01

    A heterogeneous nanocomposite catalyst constructed by the Co3O4 nanorods decorated with the Cu2O quantum dots (QDs) were successfully synthesized via a simple hydrothermal method followed by an oxidation-reduction processing. The fabricated Cu2O/Co3O4 nanocomposite was characterized by the SEM, TEM, XPS, XRD, UV-vis and PL, and the (2 2 0) and (3 1 1) facets of the Co3O4 were exposed. Compared with the original Co3O4 nanorods with an average diameter of 350 nm, a substantial decrease in the band gap was observed after doping the nanorods with the Cu2O QDs (average diameter of 5 nm). Such a dramatic decrease in the band gap indicated a significant enhancement of the photocatalytic activities under visible light. The methylene blue (MB) dye and the phenol were used as model organic pollutants, and the Cu2O/Co3O4 nanocomposite catalyst exhibited both high catalytic activity and good recycling stability. The catalytic activities of the Cu2O/Co3O4/potassium monopersulfate triple salt (PMS) system for cleaving the MB and the phenol were dependent on the dosages of the Cu2O QDs, and the calculated degradation rates achieved by 7.0 wt% Cu2O/Co3O4 nanocomposite catalyst were about 11.3 and 1.8 times than that of the pristine Co3O4 nanorod catalyst for the MB and the phenol, respectively. The reactive species of rad O2- and the holes were determined to be the main active species for the phenol photocatalytic degradation by the 7 wt% Cu2O/Co3O4/PMS system and the 7 wt% Cu2O/Co3O4/H2O2 system, respectively.

  12. The ideal Atomic Centre; Le Centre Atomique ideal

    Energy Technology Data Exchange (ETDEWEB)

    Mas, R. [Commissariat a l' Energie Atomique, Saclay (France). Centre d' Etudes Nucleaires

    1965-07-01

    The author presents considerations which should prove to be of interest to all those who have to design, to construct and to operate a nuclear research centre. A large number of the ideas presented can also be applied to non-nuclear scientific research centres. In his report the author reviews: various problems with which the constructor is faced: ground-plan, infrastructure, buildings and the large units of scientific equipment in the centre, and those problems facing the director: maintenance, production, supplies, security. The author stresses the relationship which ought to exist between the research workers and the management. With this aim in view he proposes the creation of National School for Administration in Research which would train administrative executives for public or private organisations; they would be specialised in the fields of fundamental or applied research. (author) [French] L'auteur propose une base de reflexions a tous ceux qui doivent concevoir, realiser et faire vivre un Centre d'Etudes Nucleaires. Un grand nombre des idees exprimees peut d'ailleurs s'appliquer a un Centre d'Etudes Scientifiques non nucleaires. Dans son ouvrage, l'auteur passe en revue les differents problemes qui se posent au constructeur: plan, masse, infrastructure, batiments et grands appareils du Centre, et ceux qu'a a resoudre le directeur: entretien, fabrication, approvisionnements, securite. L'auteur insiste sur l'aspect des rapports qui doivent exister entre les chercheurs et ceux qui les administrent. Il propose a cette fin la creation d'une Ecole Nationale d'Administration de la Recherche qui formerait des cadres administratifs pour les organismes publics ou prives, specialises dans la Recherche fondamentale ou appliquee. (auteur)

  13. The Galactic centre pulsar population

    CERN Document Server

    Chennamangalam, Jayanth

    2013-01-01

    The recent discovery of a magnetar in the Galactic centre region has allowed Spitler et al. to characterize the interstellar scattering in that direction. They find that the temporal broadening of the pulse profile of the magnetar is substantially less than that predicted by models of the electron density of that region. This raises the question of what the plausible limits for the number of potentially observable pulsars - i.e., the number of pulsars beaming towards the Earth - in the Galactic centre region are. In this paper, using realistic assumptions, we show that the potentially observable population of pulsars in the inner parsec has a conservative upper limit of $\\sim$950, and that it is premature to conclude that the number of pulsars in this region is small. We also show that the observational results so far are consistent with this number and make predictions for future radio pulsar surveys of the Galactic centre.

  14. Construction of the Wigner Data Centre

    CERN Multimedia

    2013-01-01

    A remote extension of the CERN data centre has recently been inaugurated. Hosted at the Wigner Research Centre for Physics in Hungary, it provides extra computing power required to cover CERN’s needs. This video presents the construction of the Wigner Data Centre from initial demolishing work through to its completion and details the major technical characteristics of the Data Centre.

  15. Complex dynamics in planar two-electron quantum dots

    Energy Technology Data Exchange (ETDEWEB)

    Schroeter, Sebastian Josef Arthur

    2013-06-25

    Quantum dots play an important role in a wide range of recent experimental and technological developments. In particular they are promising candidates for realisations of quantum bits and further applications in quantum information theory. The harmonically confined Hooke's atom model is experimentally verified and separates in centre-of-mass and relative coordinates. Findings that are contradictory to this separability call for an extension of the model, in particular changing the confinement potential. In order to study effects of an anharmonic confinement potential on spectral properties of planar two-electron quantum dots a sophisticated numerical approach is developed. Comparison between the Helium atom, Hooke's atom and an anharmonic potential model are undertaken in order to improve the description of quantum dots. Classical and quantum features of complexity and chaos are investigated and used to characterise the dynamics of the system to be mixed regular-chaotic. Influence of decoherence can be described by quantum fidelity, which measures the effect of a perturbation on the time evolution. The quantum fidelity of eigenstates of the system depends strongly on the properties of the perturbation. Several methods for solving the time-dependent Schrödinger equation are implemented and a high level of accuracy for long time evolutions is achieved. The concept of offset entanglement, the entanglement of harmonic models in the noninteracting limit, is introduced. This concept explains different questions raised in the literature for harmonic quantum dot models, recently. It shows that only in the groundstate the electrons are not entangled in the fermionic sense. The applicability, validity, and origin of Hund's first rule in general quantum dot models is further addressed. In fact Hund's first rule is only applicable, and in this case also valid, for one pair of singlet and triplet states in Hooke's atom. For more realistic models of two

  16. Complex dynamics in planar two-electron quantum dots

    International Nuclear Information System (INIS)

    Quantum dots play an important role in a wide range of recent experimental and technological developments. In particular they are promising candidates for realisations of quantum bits and further applications in quantum information theory. The harmonically confined Hooke's atom model is experimentally verified and separates in centre-of-mass and relative coordinates. Findings that are contradictory to this separability call for an extension of the model, in particular changing the confinement potential. In order to study effects of an anharmonic confinement potential on spectral properties of planar two-electron quantum dots a sophisticated numerical approach is developed. Comparison between the Helium atom, Hooke's atom and an anharmonic potential model are undertaken in order to improve the description of quantum dots. Classical and quantum features of complexity and chaos are investigated and used to characterise the dynamics of the system to be mixed regular-chaotic. Influence of decoherence can be described by quantum fidelity, which measures the effect of a perturbation on the time evolution. The quantum fidelity of eigenstates of the system depends strongly on the properties of the perturbation. Several methods for solving the time-dependent Schrödinger equation are implemented and a high level of accuracy for long time evolutions is achieved. The concept of offset entanglement, the entanglement of harmonic models in the noninteracting limit, is introduced. This concept explains different questions raised in the literature for harmonic quantum dot models, recently. It shows that only in the groundstate the electrons are not entangled in the fermionic sense. The applicability, validity, and origin of Hund's first rule in general quantum dot models is further addressed. In fact Hund's first rule is only applicable, and in this case also valid, for one pair of singlet and triplet states in Hooke's atom. For more realistic models of two-electron quantum dots an

  17. LDE centres: sprint or marathon?

    NARCIS (Netherlands)

    Bonger, S.; Van Rein, E.

    2015-01-01

    The aim of the Strategic Leiden-Delft-Erasmus Alliance, established by the three universities in 2012, was to improve research and education and competitiveness. Projects are intended to develop from the ground up, which led to the establishment of eight joint centres in 2013. A quick look around re

  18. Fossil Dot Com

    DEFF Research Database (Denmark)

    2011-01-01

    Since the start of the industrial revolution in 1800, with breakthrough innovations in iron production, textile industry and the steam engine, society has sustained incredible growth and transformation. During the 200 years, worldwide individual productivity has grown more than 32 times...... technological examples from his background as director of the innovation centre at DONG Energy, Charles Nielsen will discuss the impact of upcoming changes to the backbone of industry: the energy supply. DONG Energy has an ambitious strategy of changing the energy supply from 15% to 85% renewable energy before...

  19. Quantum dots: Rethinking the electronics

    Science.gov (United States)

    Bishnoi, Dimple

    2016-05-01

    In this paper, we demonstrate theoretically that the Quantum dots are quite interesting for the electronics industry. Semiconductor quantum dots (QDs) are nanometer-scale crystals, which have unique photo physical, quantum electrical properties, size-dependent optical properties, There small size means that electrons do not have to travel as far as with larger particles, thus electronic devices can operate faster. Cheaper than modern commercial solar cells while making use of a wider variety of photon energies, including "waste heat" from the sun's energy. Quantum dots can be used in tandem cells, which are multi junction photovoltaic cells or in the intermediate band setup. PbSe (lead selenide) is commonly used in quantum dot solar cells.

  20. Electroluminescent hybrid organic/inorganic quantum dot devices

    International Nuclear Information System (INIS)

    The synthesis of PbS crystallites in aqueous solution in the presence of ethylenediaminetetraacetic acid (EDTA) has been investigated. Nanocrystalline material exhibiting charge confinement effects have been observed. The factors affecting crystallite growth, and hence the optical properties of the ultimately synthesised sample have been studied. A simple analytical model of the linear optical properties of quantum dots of finite size distribution has been developed. The model has been used in conjunction with the effective mass approximation (EMA) in order to model the optical properties of the synthesised PbS with a great deal of success. The EMA is found to limit the applicability of the optical model to samples of quantum dots consisting of larger crystallites as one would expect. Size-quantised CdSe particles have also been synthesised in aqueous solution. The same optical model successfully models the absorption spectra of these quantum dots, subject to the constraints of the EMA. Excessive scattering of light in solutions containing flocculated and/or bulk material is also found to limit the applicability of the model. The incorporation of colloidally suspended quantum dots into optoelectronic device structures has been considered. Energy level offsets between the quantum dots and host matrices have been studied and have been found to be unfavourable to the injection of electronic charge from the matrix into the dots. Alternative electroluminescent device structures in which the quantum dots are incorporated into electroluminescent host matrices which optically pump the quantum dots have therefore been proposed. Such devices have proved difficult to fabricate, eventual luminescence from quantum dot surface states having been obtained, but luminescence from the quantum dot effective bandgap not having been obtained. The scope of the project has extended to the investigation of charge injection into the quantum dot matrix materials themselves from the device

  1. Photonics of shungite quantum dots

    OpenAIRE

    Razbirin, Boris S.; Rozhkova, Natalia N.; Sheka, Elena F.

    2014-01-01

    Shungite quantum dots are associated with nanosize fragments of reduced graphene oxide similarly to synthetic graphene quantum dots thus forming a common class of GQDs. Colloidal dispersions of powdered shungite in water, carbon tetrachloride, and toluene form the ground for the GQD photonic peculiarities manifestation. Morphological study shows a steady trend of GQDs to form fractals and a drastic change in the colloids fractal structure caused by solvent was reliably established. Spectral s...

  2. Spin pumping through quantum dots

    OpenAIRE

    Rojek, Stephan; Governale, Michele; König, Jürgen

    2013-01-01

    We propose schemes for generating spin currents into a semiconductor by adiabatic or non-adiabatic pumping of electrons through interacting quantum dots. The appeal of such schemes lies in the possibility to tune the pumping characteristics via gate voltages that control the properties of the quantum dot. The calculations are based on a systematic perturbation expansion in the tunnel-coupling strength and the pumping frequency, expressed within a diagrammatic real-time technique. Special focu...

  3. The INTEGRAL Science Data Centre

    OpenAIRE

    Beckmann, V.

    2002-01-01

    The INTEGRAL Science Data Centre (ISDC) processes, archives and distributes data from the INTEGRAL mission. At the ISDC incoming data from the satellite are processed and searched for transient sources and Gamma-Ray bursts. The data are archived and distributed to the guest observers. As soon as the data are public, any astronomer can access the data via the internet. ISDC also provides the tools which are necessary for the data analysis and offers user support concerning questions related to...

  4. Radwaste Treatment Centre Jaslovske Bohunice

    International Nuclear Information System (INIS)

    In this leaflet the Bohunice Radwaste Treatment Centre (BSC RAO) is presented. BSC RAO is designed to process and treat liquid and solid radwaste, arising from the NPP A-1 decommissioning, from NPPs V-1, V-2, and Mochovce operations, as well as institutional radwaste of diverse institutional (hospitals, research institutes) in the Slovak Republic. Transport, sorting, incineration, compacting, concentration and cementation of radwaste as well as monitoring of emission are described

  5. Fuzzy dot ideals and fuzzy dot H-ideals of BCH-algebras

    Institute of Scientific and Technical Information of China (English)

    PENG Jia-yin

    2008-01-01

    The notions of fuzzy dot ideals and fuzzy dot H-ideals in BCH-algebras are intro duced,several appropriate examples are provided,and their some properties are investigated.The relations among fuzzy ideal,fuzzy H-ideal,fuzzy dot ideal and fuzzy dot H-ideals in BCH algebras are discussed,several equivalent depictions of fuzzy dot ideal are obtained. How to deal with the homomorphic image and inverse image of fuzzy dot ideals (fuzzy dot H-ideals) are studied. The relations between a fuzzy dot ideal (fuzzy dot H-ideal) in BCH-algebras and a fuzzy dot ideal (fuzzy dot H-ideal) in the product algebra of BCH-algebras are given.

  6. The Notting Dale Urban Studies Centre

    Science.gov (United States)

    Webb, Chris; Lynas, Sue

    1976-01-01

    Founded in 1974, the Centre is one of the most intensively used resource centres in the United Kingdom. Adults and students from elementary to college level use its facilities to learn about the urban environment. (BD)

  7. Single to quadruple quantum dots with tunable tunnel couplings

    Energy Technology Data Exchange (ETDEWEB)

    Takakura, T.; Noiri, A.; Obata, T.; Yoneda, J.; Yoshida, K. [Department of Applied Physics, University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-8656 (Japan); Otsuka, T.; Tarucha, S. [Department of Applied Physics, University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-8656 (Japan); RIKEN, Center for Emergent Matter Science, 3-1 Wako-shi, Saitama 351-0198 (Japan)

    2014-03-17

    We prepare a gate-defined quadruple quantum dot to study the gate-tunability of single to quadruple quantum dots with finite inter-dot tunnel couplings. The measured charging energies of various double dots suggest that the dot size is governed by the gate geometry. For the triple and quadruple dots, we study the gate-tunable inter-dot tunnel couplings. For the triple dot, we find that the effective tunnel coupling between side dots significantly depends on the alignment of the center dot potential. These results imply that the present quadruple dot has a gate performance relevant for implementing spin-based four-qubits with controllable exchange couplings.

  8. Near-infrared quantum dots for HER2 localization and imaging of cancer cells

    OpenAIRE

    Rizvi SB; Rouhi S; Taniguchi S; Yang SY; Green M; Keshtgar M; Seifalian AM

    2014-01-01

    Sarwat B Rizvi,1 Sepideh Rouhi,1 Shohei Taniguchi,2 Shi Yu Yang,1 Mark Green,2 Mo Keshtgar,1,3 Alexander M Seifalian1,3 1UCL Centre for Nanotechnology and Regenerative Medicine, University College London, 2Department of Physics, King's College London, 3Royal Free London NHS Foundation Trust Hospital, London, UK Background: Quantum dots are fluorescent nanoparticles with unique photophysical properties that allow them to be used as diagnostic, therapeutic, and theranostic agents, part...

  9. InAs/GaAs submonolayer quantum dot superluminescent diode emitting around 970 nm

    Institute of Scientific and Technical Information of China (English)

    Li Xin-Kun; Liang De-Chun; Jin Peng; An Qi; Wei Heng; Wu Jian; Wang Zhan-Guo

    2012-01-01

    According to the InAs/GaAs submonolayer quantum dot active region,we demonstrate a bent-waveguide superlnminescent diode emitting at a wavelength of around 970 nm.At a pulsed injection current of 0.5 A,the device exhibits an output power of 24 mW and an emission spectrum centred at 971 nm with a full width at half maximum of 16 nm.

  10. Engineering colloidal quantum dot solids within and beyond the mobility-invariant regime

    KAUST Repository

    Zhitomirsky, David

    2014-05-06

    © 2014 Macmillan Publishers Limited. Colloidal quantum dots are attractive materials for efficient, low-cost and facile implementation of solution-processed optoelectronic devices. Despite impressive mobilities (1-30 cm2V-1 s-1) reported for new classes of quantum dot solids, it is-surprisingly-the much lower-mobility (10-3-10-2 cm2V-1 s-1) solids that have produced the best photovoltaic performance. Here we show that it is not mobility, but instead the average spacing among recombination centres that governs the diffusion length of charges in today\\'s quantum dot solids. In this regime, colloidal quantum dot films do not benefit from further improvements in charge carrier mobility. We develop a device model that accurately predicts the thickness dependence and diffusion length dependence of devices. Direct diffusion length measurements suggest the solid-state ligand exchange procedure as a potential origin of the detrimental recombination centres. We then present a novel avenue for in-solution passivation with tightly bound chlorothiols that retain passivation from solution to film, achieving an 8.5% power conversion efficiency.

  11. Mitsui model with diagonal strains: A unified description of external pressure effect and thermal expansion of Rochelle salt NaKC4H4O6·4H2O

    Directory of Open Access Journals (Sweden)

    I.R. Zachek

    2011-12-01

    Full Text Available We elaborate a modification of the deformable two-sublattice Mitsui model of [Levitskii R.R. et al., Phys. Rev. B. 2003, Vol. 67, 174112] and [Levitskii R.R. et al., Condens. Matter Phys., 2005, Vol. 8, 881] that consistently takes into account diagonal components of the strain tensor, arising either due to external pressures or due to thermal expansion. We calculate the related to those strains thermal, piezoelectric, and elastic characteristics of the system. Using the developed fitting procedure, a set of the model parameters is found for the case of Rochelle salt crystals, providing a satisfactory agreement with the available experimental data for the hydrostatic and uniaxial pressure dependences of the Curie temperatures, temperature dependences of spontaneous diagonal strains, linear thermal expansion coefficients, elastic constants cijE and ci4E, piezoelectric coefficients d1i and g1i (i=1,2,3. The hydrostatic pressure variation of dielectric permittivity is described using a derived expression for the permittivity of a partially clamped crystal. The dipole moments and the asymmetry parameter of Rochelle salt are found to increase with hydrostatic pressure.

  12. Rapid Thermolysis Studies of [Pb2(TNR)2(CHZ)2(H2O)2]·4H2O and Cd(CHZ)2(TNR)(H2O)

    Institute of Scientific and Technical Information of China (English)

    ZUO, Xiao-Li; QIAO, Xiao-Jing; SUN,Yuan-Hua; ZHANG, Tong-Lai; ZHANG, Jian-Guo; YANG, Li; WANG, Shao-Zong

    2007-01-01

    T-jump/FT-IR spectroscopy was used to study the rapid thermal decomposition activity of the major gaseous products of flash pyrolysis of Cd(CHZ)2(TNR)(H2O). Thus Cd(CHZ)2(TNR)(H2O) is not an eco-friendly and chemically compatible primary explosive. Both compounds liberate volatile metal carbonate, oxide and isocyanate compounds. The combustion temperature and products of the two compounds were calculated by Real code. The results of theoretical calculation show that the combustion temperature of tion products and the amount of NO is less than the experiment result from T-jump/FTIR.

  13. An Efficient and Green Synthesis of 5-Oxo-5,6,7,8-tetrahydro 4H-benzo-[b]-pyran Derivatives Promoted by InCl3·4H2O Under Microwave Irradiation

    Institute of Scientific and Technical Information of China (English)

    Xue Yuan HU; Xue Sen FAN; Xin Ying ZHANG; Gui Rong QU; Yan Zhen LI

    2005-01-01

    A rapid and facile preparation of benzo-[b]-pyran derivatives through condensation of chalcone and 5, 5-dimethyl-1,3-cyclohexandione under microwave irradiation in the presence of simplicity and environmental benignancy, this method may provide a useful alternative for the preparation of benzo-[b]-pyran derivatives.

  14. [Bmim]BF4-H2O体系超额摩尔体积测定及关联%Measurement and Correlation of Excess Molar Volume for the [Bmim]BF4-H2O System

    Institute of Scientific and Technical Information of China (English)

    方伟慧; 林金清; 王国平; 金春英

    2010-01-01

    合成并表征离子液体1-丁基-3-甲基咪唑四氟硼酸盐([Bmim]BF4),测定[Bmim]BF4-H2O二元混合物在不同温度下的密度值和超额摩尔体积.结果表明,在所有组成范围内,体系的超额摩尔体积都为正值,且不同温度下的等温线都存在一极大值点;同时,所有等温线的极值点所对应的H2O的摩尔分数基本上在50%左右.不同温度下超额摩尔集体的变化趋势相似,而在组成相同的情况下,随着温度的增加,超额摩尔体积变大.采用Redlich-Kister方程对[Bmim]BF4-H2O的超额摩尔体积进行关联,最大标准偏差为1.32%.

  15. Ca(NO3)2·4H2O-catalysed Biginelli Reaction: One-pot Synthesis of 1,2,3,4-Tetrahydropyrimidin-2-ones/pyrimidine-2-thiones under Solvent-free Conditions

    Institute of Scientific and Technical Information of China (English)

    DEBACHE Abdelmadjid; BOULCINA Raouf; TAFER Radia; BELFAITAH Ali; RHOUATI Salah; CARBONI Bertrand

    2008-01-01

    The synthesis of 1,2,3,4-dihydropyrimidinone/thione derivatives was achieved in good to excellent yields using calcium(Ⅱ)nitrate as catalyst to promote the Biginelli three-component condensation reaction from a diversity of aromatic aldehydes,β-keto compounds and urea or thiourea.The reaction was carried out under solvent-free condi-tions.

  16. The effect of transverse electric fields on dielectric, piezoelectric, elastic and thermal properties of the Rochelle salt NaKC4H4O6 · 4H2O

    Directory of Open Access Journals (Sweden)

    R.R. Levitskii

    2009-01-01

    Full Text Available Modified four-sublattice model for Rochelle salt by taking into account piezoelectric interactions with shear strain ε4 , ε5 and ε6 is proposed. Components of polarization vector and static dielectric permittivity tensor for both mechanically clamped and free crystals, their piezoelectric characteristics and elastic modules are derived in the mean field approximation. A comprehensive study of transverse field effect on phase transition temperatures, dielectric and elastic properties of Rochelle salt has been performed for the first time.

  17. Esperanzaite, NaCa(2)Al(2)(As(5+)O(4))[As(5+)O(3)(OH)](OH)(2)F(4)(H(2)O), A New Mineral From Mina La Esperanza, Mexico: Descriptive Mineralogy and Atomic Arrangement

    Energy Technology Data Exchange (ETDEWEB)

    Cureton, F.; Falster, A.U.; Foord, E.E.; Hlava, P.F.; Hughes, J.M.; Maxwell, C.H.

    1998-11-09

    Esperanzaite, ideally NaCazA12(As5+0.i)[As5+03 (OH)] (OH)2FJH20), Z =2, is a new mineral from the Mina h Esperarq Durango State, Mexico. The mineral occurs as blue-green botryoidal crystalline masses on rhyolite, with separate spheres up to 1.5 mm Y Deceased in diameter. Mobs hardness is 4.5, specific gravity 3.240h, and 3.36( 3)C.IC. Optical properties were measured in 589 nm light. Esperanzaite is biaxial (-), .Y= Y = Z= colorless, a 1.580(1), ~ 1.588( 1), and y 1.593(1 ); 2V0hs is 74(1 ~ and 2 }'CUIC is 76.3". Dispersion is medium, r < v, and optic axes are oriented as a A Z = +50.5o, b = Y, c P. X = +35". The five strongest X-ray diffraction maxima in the powder pattern are (~ /, hk~: 2.966,100, 13 i, 31 i, 031 ; 3.527,90, 220; 2.700,90,221,002, 040; 5.364>80, 001, 020; 4.796,80,011. Esperanzaite is monoclinic, u 9.687(5), b 10.7379(6), c 5.5523(7)& ~ 105.32( 1 )", space group P21/nz. The atomic arrangement of esperanzaite was solved by Direct Methods and Fourier analysis (R= 0.03 1). The Fundamental Building Block is formed of stacks of heteropolyhedral tetramers; the tetramers are formed of two arsenate tetrahedral and two Al octahedra, comer-linked in 4-member rings. The Fundamental Building Blocks are linked by irregular lda~j and Ca@ polyhedra.

  18. Rapid synthesis of novel flowerlike K0.46Mn2O4(H2O)1.4 hierarchical architectures and their catalytic degradation of formaldehyde in aqueous solution

    Science.gov (United States)

    Ahmed, Khalid Abdelazez Mohamed; Huang, Kaixun

    2014-04-01

    Novel flower-like birnessite type manganese oxide hierarchical architectures were hydrothermally synthesized from KMnO4 solution using sodium fluorite as a reductant in sulfuric acid medium at low temperature. X-ray diffraction (XRD), Fourier transform infrared (FT-IR) and X-ray photoelectron (XPS) spectroscopes confirm that the composition of the as-fabricated product. Field emission scanning electron microscopy (FE-SEM), transmission electron microscopy (TEM), selected area electron diffraction (SA-ED), high resolution transmission electron microscopy (HR-TEM) and N2 adsorption-desorption isotherm reveal that the as-synthesized sample exhibits a microsized flower-like crystal with dense nanoleaves standing on their surfaces, polycrystalline, monoclinic phase structure and high BET surface area. On the basis of time-dependent experimental results, a possible mechanism for the formation of flowerlike structures is speculated. Their capability of catalytic degradation of formaldehyde solution with oxygen air bubbles were studied by using an acetylacetone calorimetric spectra, total organic carbon (TOC) method and turnover number (TON). In addition, the birnessite nanoflower is stable during the reaction and can be used repeatedly.

  19. Scheduling participants of Assessment Centres

    DEFF Research Database (Denmark)

    Lysgaard, Jens; Løber, Janni

      Assessment Centres are used as a tool for psychologists and coaches to observe a number of dimensions in a person's behaviour and test his/her potential within a number of chosen focus areas. This is done in an intense course, with a number of different exercises which expose each participant......'s ability level in the chosen focus areas. The participants are observed by assessors with the purpose of gathering material for reaching a conclusion on each participant's personal profile. We consider the particular case that arises at the company Human Equity (www.humanequity.dk), where Assessment...

  20. Optical Fiber Sensing Using Quantum Dots

    OpenAIRE

    Faramarz Farahi; José Luís Santos; Tito Trindade; Manuel António Martins; Pedro Jorge

    2007-01-01

    Recent advances in the application of semiconductor nanocrystals, or quantum dots, as biochemical sensors are reviewed. Quantum dots have unique optical properties that make them promising alternatives to traditional dyes in many luminescence based bioanalytical techniques. An overview of the more relevant progresses in the application of quantum dots as biochemical probes is addressed. Special focus will be given to configurations where the sensing dots are incorporated in sol...

  1. A colloidal quantum dot spectrometer

    Science.gov (United States)

    Bao, Jie; Bawendi, Moungi G.

    2015-07-01

    Spectroscopy is carried out in almost every field of science, whenever light interacts with matter. Although sophisticated instruments with impressive performance characteristics are available, much effort continues to be invested in the development of miniaturized, cheap and easy-to-use systems. Current microspectrometer designs mostly use interference filters and interferometric optics that limit their photon efficiency, resolution and spectral range. Here we show that many of these limitations can be overcome by replacing interferometric optics with a two-dimensional absorptive filter array composed of colloidal quantum dots. Instead of measuring different bands of a spectrum individually after introducing temporal or spatial separations with gratings or interference-based narrowband filters, a colloidal quantum dot spectrometer measures a light spectrum based on the wavelength multiplexing principle: multiple spectral bands are encoded and detected simultaneously with one filter and one detector, respectively, with the array format allowing the process to be efficiently repeated many times using different filters with different encoding so that sufficient information is obtained to enable computational reconstruction of the target spectrum. We illustrate the performance of such a quantum dot microspectrometer, made from 195 different types of quantum dots with absorption features that cover a spectral range of 300 nanometres, by measuring shifts in spectral peak positions as small as one nanometre. Given this performance, demonstrable avenues for further improvement, the ease with which quantum dots can be processed and integrated, and their numerous finely tuneable bandgaps that cover a broad spectral range, we expect that quantum dot microspectrometers will be useful in applications where minimizing size, weight, cost and complexity of the spectrometer are critical.

  2. Core Competencies Of A Call Centre AgentCore Competencies Of A Call Centre Agent

    OpenAIRE

    Christine White; Vera Roos

    2005-01-01

    Call centre agents are becoming increasingly important in the call centre context. They act as a contact point between the customer and the company. Call centre agents should have certain competencies to perform their duties sufficiently. Identifying competencies, required to be effective agents, will ease the task of training and recruitment. Due to the interrelatedness of the call centre agent, the management of a call centre and customers, all relevant role players’ perceptions were taken ...

  3. Quantum-dot emitters in photonic nanostructures

    DEFF Research Database (Denmark)

    Hvam, Jørn Märcher; Stobbe, Søren; Lodahl, Peter

    2010-01-01

    The spontaneous emission from self-assembled semiconductor quantum dots is strongly influenced by the environment in which they are placed. This can be used to determine fundamental optical properties of the quantum dots as well as to manipulate and control the quantum-dot emission itself....

  4. Beer's law in semiconductor quantum dots

    CERN Document Server

    Adamashvili, G T

    2010-01-01

    The propagation of a coherent optical linear wave in an ensemble of semiconductor quantum dots is considered. It is shown that a distribution of transition dipole moments of the quantum dots changes significantly the polarization and Beer's absorption length of the ensemble of quantum dots. Explicit analytical expressions for these quantities are presented.

  5. Perceptual centres in speech - an acoustic analysis

    Science.gov (United States)

    Scott, Sophie Kerttu

    Perceptual centres, or P-centres, represent the perceptual moments of occurrence of acoustic signals - the 'beat' of a sound. P-centres underlie the perception and production of rhythm in perceptually regular speech sequences. P-centres have been modelled both in speech and non speech (music) domains. The three aims of this thesis were toatest out current P-centre models to determine which best accounted for the experimental data bto identify a candidate parameter to map P-centres onto (a local approach) as opposed to the previous global models which rely upon the whole signal to determine the P-centre the final aim was to develop a model of P-centre location which could be applied to speech and non speech signals. The first aim was investigated by a series of experiments in which a) speech from different speakers was investigated to determine whether different models could account for variation between speakers b) whether rendering the amplitude time plot of a speech signal affects the P-centre of the signal c) whether increasing the amplitude at the offset of a speech signal alters P-centres in the production and perception of speech. The second aim was carried out by a) manipulating the rise time of different speech signals to determine whether the P-centre was affected, and whether the type of speech sound ramped affected the P-centre shift b) manipulating the rise time and decay time of a synthetic vowel to determine whether the onset alteration was had more affect on P-centre than the offset manipulation c) and whether the duration of a vowel affected the P-centre, if other attributes (amplitude, spectral contents) were held constant. The third aim - modelling P-centres - was based on these results. The Frequency dependent Amplitude Increase Model of P-centre location (FAIM) was developed using a modelling protocol, the APU GammaTone Filterbank and the speech from different speakers. The P-centres of the stimuli corpus were highly predicted by attributes of

  6. The new AMS control centre

    CERN Multimedia

    Anaïs Schaeffer

    2011-01-01

    Construction work for the future AMS control room began in November 2010 and should be finished this June. The new building, which will have been completed in record time thanks to the professionalism of the project team, will soon be ready to receive the initial data from the AMS experiment.     Luigi Scibile and Michael Poehler, from the GS department, at the AMS control centre construction site.   The Alpha Magnetic Spectrometer (AMS) is due to wing its way towards the International Space Station (ISS) on board the shuttle Discovery in April. Mainly intended for research on antimatter and dark matter, the data collected by AMS will be sent to Houston in the United States and then directly to CERN’s new Building 946. Construction work for the AMS control centre building on the Route Gentner at CERN’s Prévessin site started in November 2010 and must be completed in time to receive the first data from the spectrometer in June. “It normall...

  7. Spin storage in quantum dot ensembles and single quantum dots

    Energy Technology Data Exchange (ETDEWEB)

    Heiss, Dominik

    2009-10-15

    This thesis deals with the investigation of spin relaxation of electrons and holes in small ensembles of self-assembled quantum dots using optical techniques. Furthermore, a method to detect the spin orientation in a single quantum dot was developed in the framework of this thesis. A spin storage device was used to optically generate oriented electron spins in small frequency selected quantum dot ensembles using circularly polarized optical excitation. The spin orientation can be determined by the polarization of the time delayed electroluminescence signal generated by the device after a continuously variable storage time. The degree of spin polarized initialization was found to be limited to 0.6 at high magnetic fields, where anisotropic effects are compensated. The spin relaxation was directly measured as a function of magnetic field, lattice temperature and s-shell transition energy of the quantum dot by varying the spin storage time up to 30 ms. Very long spin lifetimes are obtained with a lower limit of T{sub 1}=20 ms at B=4 T and T=1 K. A strong magnetic field dependence T{sub 1}{proportional_to}B{sup -5} has been observed for low temperatures of T=1 K which weakens as the temperature is increased. In addition, the temperature dependence has been determined with T{sub 1}{proportional_to}T{sup -1}. The characteristic dependencies on magnetic field and temperature lead to the identification of the spin relaxation mechanism, which is governed by spin-orbit coupling and mediated by single phonon scattering. This finding is qualitatively supported by the energy dependent measurements. The investigations were extended to a modified device design that enabled studying the spin relaxation dynamics of heavy holes in self-assembled quantum dots. The measurements show a polarization memory effect for holes with up to 0.1 degree of polarization. Furthermore, investigations of the time dynamics of the hole spin relaxation reveal surprisingly long lifetimes T{sub 1}{sup h

  8. Spin storage in quantum dot ensembles and single quantum dots

    International Nuclear Information System (INIS)

    This thesis deals with the investigation of spin relaxation of electrons and holes in small ensembles of self-assembled quantum dots using optical techniques. Furthermore, a method to detect the spin orientation in a single quantum dot was developed in the framework of this thesis. A spin storage device was used to optically generate oriented electron spins in small frequency selected quantum dot ensembles using circularly polarized optical excitation. The spin orientation can be determined by the polarization of the time delayed electroluminescence signal generated by the device after a continuously variable storage time. The degree of spin polarized initialization was found to be limited to 0.6 at high magnetic fields, where anisotropic effects are compensated. The spin relaxation was directly measured as a function of magnetic field, lattice temperature and s-shell transition energy of the quantum dot by varying the spin storage time up to 30 ms. Very long spin lifetimes are obtained with a lower limit of T1=20 ms at B=4 T and T=1 K. A strong magnetic field dependence T1∝B-5 has been observed for low temperatures of T=1 K which weakens as the temperature is increased. In addition, the temperature dependence has been determined with T1∝T-1. The characteristic dependencies on magnetic field and temperature lead to the identification of the spin relaxation mechanism, which is governed by spin-orbit coupling and mediated by single phonon scattering. This finding is qualitatively supported by the energy dependent measurements. The investigations were extended to a modified device design that enabled studying the spin relaxation dynamics of heavy holes in self-assembled quantum dots. The measurements show a polarization memory effect for holes with up to 0.1 degree of polarization. Furthermore, investigations of the time dynamics of the hole spin relaxation reveal surprisingly long lifetimes T1h in the microsecond range, therefore, comparable with electron spin

  9. Centre for nuclear engineering University of Toronto annual report 1984

    International Nuclear Information System (INIS)

    The annual report of the Centre for Nuclear Engineering, University of Toronto covers the following subjects: message from the Dean; Chairman's message; origins of the centre; formation of the centre; new nuclear appointments; and activities of the centre, 1984

  10. Luminescent Surface Quaternized Carbon Dots

    KAUST Repository

    Bourlinos, Athanasios B.

    2012-01-10

    Thermal oxidation of a salt precursor made from the acid base combination of tris(hydroxymethyl)aminomethane and betaine hydrochloride results in light-emitting surface quaternized carbon dots that are water-dispersible, display anion exchange properties, and exhibit uniform size/surface charge. © 2011 American Chemical Society.

  11. On triaxial ellipsoidal quantum dots

    Energy Technology Data Exchange (ETDEWEB)

    Voon, L C Lew Yan; Willatzen, M [Mads Clausen Institute, University of Southern Denmark, Grundtvigs Alle 150, DK-6400 Soenderborg (Denmark)

    2004-02-25

    The bound-state problem for triaxial ellipsoidal infinite-barrier quantum dots has been solved. It is exactly solvable in terms of ellipsoidal coordinates and the eigenmodes are written in terms of Lame wavefunctions. The need for all eight types of functions is shown. This presents a generalization over previous work on spheres and spheroids. Splitting of degeneracy and level crossing are obtained.

  12. DOT strategies versus orbiter strategies

    NARCIS (Netherlands)

    Rutten, R.J.

    2001-01-01

    The Dutch Open Telescope is a high-resolution solar imager coming on-line at La Palma. The definition of the DOT science niche, strategies, and requirements resemble Solar Orbiter considerations and deliberations. I discuss the latter in the light of the former, and claim that multi-line observation

  13. Vertical asymmetric double quantum dots

    Science.gov (United States)

    Roßbach, R.; Reischle, M.; Beirne, G. J.; Schweizer, H.; Jetter, M.; Michler, P.

    2007-01-01

    Two layers of differently sized self-assembled InP-quantum dots (QDs) separated by a GaInP spacer layer with varying thickness were grown by metal organic vapor phase epitaxy (MOVPE). Photoluminescence measurements of the QD ensembles and of individual asymmetric double QDS show coupling due to the tunnelling of carriers.

  14. Powering the Future Data Centre

    DEFF Research Database (Denmark)

    Zhang, Zhe

    2010-01-01

    The extended run Uninterruptible Power Supply system (UPSs) which powered by fuel cells and supercapcitors, is a promising solution for future data centre to obtain environmentfriendly energy efficient and cost effective. There are many challenges in power electronic interface circuits, because......: • Optimized design method for dual active bridge (DAB) converter and its derived circuits; • A novel hybrid dc-dc converter and its corresponding optimal design method are proposed; • An improved dual input current-fed DC-DC converter with bidirectional power conversion ability is investigated; • Extend...... the circuit level decoupling modulation scheme into 3LNPC inverter. As to the DAB converter, through the power factor and harmonics analysis, the dominated loss factor is found in variable input voltage range. Optimized parameter choosing method is used to decide the ac inductance and switching frequency...

  15. Hyperdense dots mimicking microcalcifications : Mammographic findings

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Nam Hyeon; Park, Jeong Mi; Goo, Hyun Woo; Bang, Sun Woo [Asan Medical Center, University of Ulsan College of Medicine, Seoul (Korea, Republic of)

    1996-12-01

    To differentiate fine hyperdense dots mimicking microcalcifications from true microcalcifications on mammography. Mammograms showing hyperdense dots in ten patients (mean age, 59 years) were evaluated. Two radiologists were asked to differentiate with the naked eye the hyperdense dots seen on ten mammograms and proven microcalcifications seen on ten mammograms. Densitometry was also performed for all lesions and the contrast index was calculated. The shape and distribution of the hyperdense dots were evaluated and enquires were made regarding any history of breast disease and corresponding treatment. Biopsies were performed for two patients with hyperdense dots. Two radiologists made correct diagnoses in 19/20 cases(95%). The contrast index was 0.10-0.88 (mean 0.58) for hyperdense dots and 0.02-0.45 (mean 0.17) for true microcalcifications. The hyperdense dots were finer and homogeneously rounder than the microcalcifications. Distribution of the hyperdense dots was more superficial in subcutaneous fat (seven cases) and subareolar area (six cases). All ten patients with hyperdense dots had history of mastitis and abscesses and had been treated by open drainage (six cases) and/or folk remedy (four cases). In eight patients, herb patches had been attached. Biopsies of hyperdense dots did not show any microcalcification or evidence of malignancy. These hyperdense dots were seen mainly in older patients. Their characteristic density, shape, distribution and clinical history makes differential diagnosis from true microcalcifications easy and could reduce unnecessary diagnostic procedures such as surgical biopsy.

  16. Hyperdense dots mimicking microcalcifications : Mammographic findings

    International Nuclear Information System (INIS)

    To differentiate fine hyperdense dots mimicking microcalcifications from true microcalcifications on mammography. Mammograms showing hyperdense dots in ten patients (mean age, 59 years) were evaluated. Two radiologists were asked to differentiate with the naked eye the hyperdense dots seen on ten mammograms and proven microcalcifications seen on ten mammograms. Densitometry was also performed for all lesions and the contrast index was calculated. The shape and distribution of the hyperdense dots were evaluated and enquires were made regarding any history of breast disease and corresponding treatment. Biopsies were performed for two patients with hyperdense dots. Two radiologists made correct diagnoses in 19/20 cases(95%). The contrast index was 0.10-0.88 (mean 0.58) for hyperdense dots and 0.02-0.45 (mean 0.17) for true microcalcifications. The hyperdense dots were finer and homogeneously rounder than the microcalcifications. Distribution of the hyperdense dots was more superficial in subcutaneous fat (seven cases) and subareolar area (six cases). All ten patients with hyperdense dots had history of mastitis and abscesses and had been treated by open drainage (six cases) and/or folk remedy (four cases). In eight patients, herb patches had been attached. Biopsies of hyperdense dots did not show any microcalcification or evidence of malignancy. These hyperdense dots were seen mainly in older patients. Their characteristic density, shape, distribution and clinical history makes differential diagnosis from true microcalcifications easy and could reduce unnecessary diagnostic procedures such as surgical biopsy

  17. Systematic safety evaluation on photoluminescent carbon dots

    Science.gov (United States)

    Wang, Kan; Gao, Zhongcai; Gao, Guo; Wo, Yan; Wang, Yuxia; Shen, Guangxia; Cui, Daxiang

    2013-03-01

    Photoluminescent carbon dots (C-dots) were prepared using the improved nitric acid oxidation method. The C-dots were characterized by tapping-mode atomic force microscopy, and UV-vis absorption spectroscopy. The C-dots were subjected to systematic safety evaluation via acute toxicity, subacute toxicity, and genotoxicity experiments (including mouse bone marrow micronuclear test and Salmonella typhimurium mutagenicity test). The results showed that the C-dots were successfully prepared with good stability, high dispersibility, and water solubility. At all studied C-dot dosages, no significant toxic effect, i.e., no abnormality or lesion, was observed in the organs of the animals. Therefore, the C-dots are non-toxic to mice under any dose and have potential use in fluorescence imaging in vivo, tumor cell tracking, and others.

  18. Spin transport through quantum dots

    Energy Technology Data Exchange (ETDEWEB)

    Lima, A.T. da Cunha; Anda, Enrique V. [Pontificia Univ. Catolica do Rio de Janeiro (PUC-Rio), RJ (Brazil)

    2003-07-01

    Full text: We investigate the spin polarized transport properties of a nanoscopic device constituted by a quantum dot connected to two leads. The electrical current circulates with a spin polarization that is modulated via a gate potential that controls the intensity of the spin-orbit coupling, the Rashba effect. We study a polarized field-effect transistor when one of its parts is constituted by a small quantum dot, which energies are controlled by another gate potential operating inside the confined region. The high confinement and correlation suffered by the charges inside the dot gives rise to novel phenomena. We show that through the manipulation of the gate potential applied to the dot it is possible to control, in a very efficient way, the intensity and polarization of the current that goes along the system. Other crucial parameters to be varied in order to understand the behavior of this system are the intensity of the external applied electric and magnetic field. The system is represented by the Anderson Impurity Hamiltonian summed to a spin-orbit interaction, which describes the Rashba effect. To obtain the current of this out-of-equilibrium system we use the Keldysh formalism.The solution of the Green function are compatible with the Coulomb blockade regime. We show that under the effect of a external magnetic field, if the dot is small enough the device operates as a complete spin filter that can be controlled by the gate potential. The behavior of this device when it is injected into it a polarized current and modulated by the Rashba effect is as well studied. (author)

  19. Smart work centres in rural areas

    DEFF Research Database (Denmark)

    Lorentzen, Anne Birte

    This paper discusses the establishment of telework centres as an element in local development strategies in rural areas, with a particular view to two new telework centres in region North Denmark. The paper argues that telework centres do not represent an easy solution to problems of local...... development and environmental sustainability, and further, that technology may not even be the most important feature needed to make them function as such....

  20. Activities of Radiation Protection Centre in 2000

    CERN Document Server

    Radiat. Prot. Cent. Vilnius

    2001-01-01

    Description of the activities of Radiation Protection Centre in 2000 is presented. Radiation Protection Centre is responsible for radiation protection issues. Currently there are six departments at Radiation Protection Centre: two in Vilnius - Department of Radiation Protection Supervision and Control and Department of Programs and Expertise, and four in the districts. Brief information on subject controlled by each departments is provided focusing on main achievements and events.

  1. Elm Farm Organic Research Centre December 2006

    OpenAIRE

    Sanders, Richard; Whiltley, Andrew; Haigh, Zoe; Clarke, Sarah; Hitchings, Roger; O'Brien, Josie

    2006-01-01

    The Organic Research Centre. Elm Farm Research Centre Bulletin with Technical Updates from The Organic Advisory Service is a regular publication from The Organic Research Centre. The current issue covers: Report from 2006 Cirencester Conference; Quest for more home produced organic food; in a world where bread matters; Improving wheat with plenty of parents; Unlocking the secrets of the ancient (cereal varieties); Brain food- a good read; Not to late to protect the future: The organic...

  2. Business plan – Tennis centre modernization

    OpenAIRE

    Moravec, Martin

    2012-01-01

    The goal of this master's thesis "Business plan -- Tennis centre modernization" - is creating and writing the business plan for the reconstruction of the existing tennis centre. The theoretical part describes characteristics of small and medium sized enterprises, their meaning. Describes the necessary parts of the business plan, its possible structure. The paper involves the knowledge gained into the concrete case of the tennis centre. Describes its nowadays conditions and possible solutions....

  3. The European NEO Coordination Centre

    Science.gov (United States)

    Perozzi, E.; Borgia, B.; Micheli, M.

    An operational approach to NEO (Near-Earth Object) hazard monitoring has been developed at European level within the framework of the Space Situational Awareness Program (SSA) of the European Space Agency (ESA). Through federating European assets and profiting of the expertise developed in European Universities and Research Centers, it has been possible to start the deployment of the so-called SSA NEO Segment. This initiative aims to provide a significant contribution to the worldwide effort to the discovery, follow-up and characterization of the near-Earth object population. A major achievement has been the inauguration in May 2013 of the ESA NEO Coordination Centre located at ESRIN (Frascati, Italy). The goal of the NEOCC Precursor Service operations is twofold: to make available updated information on the NEO population and the associated hazard and to contribute to optimize the NEO observational efforts. This is done by maintaining and improving a Web Portal publicly available at http://neo.ssa.esa.int and by performing follow-up observations through a network of collaborating telescopes and facilities. An overview of the SSA-NEO System and a summary of the first two years of NEOCC operations is presented.

  4. Laparoscopic adrenalectomy: Single centre experience.

    LENUS (Irish Health Repository)

    O'Farrell, N J

    2012-02-01

    BACKGROUND: Laparoscopic adrenalectomy is an attractive alternative to the traditional open approach in the surgical excision of an adrenal gland. It has replaced open adrenalectomy in our institution and we review our experience to date. METHODS: All cases of laparoscopic adrenalectomies in our hospital over eight years (from 2001 to May 2009) were retrospectively reviewed. Patient demographics, diagnosis, length of hospital stay, histology and all operative and post-operative details were evaluated. RESULTS: Fifty-five laparoscopic adrenalectomies (LA) were performed on 51 patients over eight years. The mean age was 48 years (Range 16-86 years) with the male: female ratio 1:2. Twenty-three cases had a right adrenalectomy, 24 had a left adrenalectomy and the remaining four patients had bilateral adrenalectomies. 91% were successfully completed laparoscopically with five converted to an open approach. Adenomas (functional and non functional) were the leading indication for LA, followed by phaeochromocytomas. Other indications for LA included Cushing\\'s disease, adrenal malignancies and rarer pathologies. There was one mortality from necrotising pancreatitis following a left adrenalectomy for severe Cushing\\'s disease, with subsequent death 10 days later. CONCLUSION: Laparoscopic adrenalectomy is effective for the treatment of adrenal tumours, fulfilling the criteria for the ideal minimally invasive procedure. It has replaced the traditional open approach in our centre and is a safe and effective alternative. However, in the case of severe Cushing\\'s disease, laparoscopic adrenalectomy has the potential for significant adverse outcomes and mortality.

  5. Oil Trading Centre to Reopen in Shanghai

    Institute of Scientific and Technical Information of China (English)

    2004-01-01

    @@ Chinese oil companies will likely resume activities at the oil trading centre in Shanghai this year, a move to further liberalize the once tightly controlled oil market. The centre will trade forward contracts for refined oil products,including gasoline, diesel oil, kerosene and fuel oil, industrial sources said.

  6. Danish Anaesthesia Allergy Centre - preliminary results

    DEFF Research Database (Denmark)

    Garvey, L H; Roed-Petersen, J; Menné, T;

    2001-01-01

    BACKGROUND: Anaphylactoid reactions in anaesthesia are rare and should ideally be investigated in specialist centres. At Gentofte University Hospital, we established such a centre in 1998 as a joint venture between the Departments of Anaesthesiology and Dermatology. We present the methodology...

  7. Neighbourhood Centres – Organisation, Management and Finance

    DEFF Research Database (Denmark)

    Larsen, Jacob Norvig

    From the late 1990s neighbourhood centres were brought to the fore of public urban regen-eration policy, because they were seen as a means to accelerate the formation of social capital in deprived urban neighbourhoods. A number of such local community centres were established with substantial pub...

  8. Constructions from Dots and Lines

    CERN Document Server

    Rodriguez, Marko A

    2010-01-01

    A graph is a data structure composed of dots (i.e. vertices) and lines (i.e. edges). The dots and lines of a graph can be organized into intricate arrangements. The ability for a graph to denote objects and their relationships to one another allow for a surprisingly large number of things to be modeled as a graph. From the dependencies that link software packages to the wood beams that provide the framing to a house, most anything has a corresponding graph representation. However, just because it is possible to represent something as a graph does not necessarily mean that its graph representation will be useful. If a modeler can leverage the plethora of tools and algorithms that store and process graphs, then such a mapping is worthwhile. This article explores the world of graphs in computing and exposes situations in which graphical models are beneficial.

  9. The role of the sexual assault centre.

    LENUS (Irish Health Repository)

    Eogan, Maeve

    2013-02-01

    Sexual Assault Centres provide multidisciplinary care for men and women who have experienced sexual crime. These centres enable provision of medical, forensic, psychological support and follow-up care, even if patients chose not to report the incident to the police service. Sexual Support Centres need to provide a ring-fenced, forensically clean environment. They need to be appropriately staffed and available 24 hours a day, 7 days a week to allow prompt provision of medical and supportive care and collection of forensic evidence. Sexual Assault Centres work best within the context of a core agreed model of care, which includes defined multi-agency guidelines and care pathways, close links with forensic science and police services, and designated and sustainable funding arrangements. Additionally, Sexual Assault Centres also participate in patient, staff and community education and risk reduction. Furthermore, they contribute to the development, evaluation and implementation of national strategies on domestic, sexual and gender-based violence.

  10. Photoactivation of silicon quantum dots

    Energy Technology Data Exchange (ETDEWEB)

    Lockwood, R., E-mail: rossl@ualberta.c [Department of Physics, University of Alberta, Edmonton, Alberta, T6G 2G7 (Canada); McFarlane, S. [Department of Physics, University of Alberta, Edmonton, Alberta, T6G 2G7 (Canada); Rodriguez Nunez, J.R. [Department of Chemistry, University of Alberta, Edmonton, Alberta, T6G 2G2 (Canada); Wang, X.Y. [Department of Physics, University of Alberta, Edmonton, Alberta, T6G 2G7 (Canada); Veinot, J.G.C. [Department of Chemistry, University of Alberta, Edmonton, Alberta, T6G 2G2 (Canada); Meldrum, A. [Department of Physics, University of Alberta, Edmonton, Alberta, T6G 2G7 (Canada)

    2011-07-15

    We show that free-standing silicon quantum dots (QDs) can be photoactivated by blue or UV optical irradiation. The luminescence intensity increases by an order of magnitude for irradiation times of several minutes under moderate optical power. The cut-off energy for photoactivation is between 2.1 and 2.4 eV, not very different from the activation energy for hydrogen dissociation from bulk silicon surfaces. We propose the mechanism for this effect is associated with silicon-hydride bond breaking and the subsequent oxidation of dangling bonds. This phenomenon could be used to 'write' luminescent quantum dots into pre-determined arrays. - Research highlights: {yields}Laser light causes increased photoluminescence intensity in silicon quantum dots. {yields} The photoactivation process is effective for wavelengths of 514 nm and shorter. {yields} Hydrogen bound to the Si-QDs is replaced by oxygen in a two-step process. {yields} Patterning is possible but limited by physical dispersion of Si-QDs.

  11. Few-electron quantum dots

    International Nuclear Information System (INIS)

    We review some electron transport experiments on few-electron, vertical quantum dot devices. The measurement of current versus source-drain voltage and gate voltage is used as a spectroscopic tool to investigate the energy characteristics of interacting electrons confined to a small region in a semiconducting material. Three energy scales are distinguished: the single-particle states, which are discrete due to the confinement involved; the direct Coulomb interaction between electron charges on the dot; and the exchange interaction between electrons with parallel spins. To disentangle these energies, a magnetic field is used to reorganize the occupation of electrons over the single-particle states and to induce changes in the spin states. We discuss the interactions between small numbers of electrons (between 1 and 20) using the simplest possible models. Nevertheless, these models consistently describe a large set of experiments. Some of the observations resemble similar phenomena in atomic physics, such as shell structure and periodic table characteristics, Hund's rule, and spin singlet and triplet states. The experimental control, however, is much larger than for atoms: with one device all the artificial elements can be studied by adding electrons to the quantum dot when changing the gate voltage. (author)

  12. Near-infrared quantum dots for HER2 localization and imaging of cancer cells

    Directory of Open Access Journals (Sweden)

    Rizvi SB

    2014-03-01

    Full Text Available Sarwat B Rizvi,1 Sepideh Rouhi,1 Shohei Taniguchi,2 Shi Yu Yang,1 Mark Green,2 Mo Keshtgar,1,3 Alexander M Seifalian1,3 1UCL Centre for Nanotechnology and Regenerative Medicine, University College London, 2Department of Physics, King's College London, 3Royal Free London NHS Foundation Trust Hospital, London, UK Background: Quantum dots are fluorescent nanoparticles with unique photophysical properties that allow them to be used as diagnostic, therapeutic, and theranostic agents, particularly in medical and surgical oncology. Near-infrared-emitting quantum dots can be visualized in deep tissues because the biological window is transparent to these wavelengths. Their small sizes and free surface reactive groups that can be conjugated to biomolecules make them ideal probes for in vivo cancer localization, targeted chemotherapy, and image-guided cancer surgery. The human epidermal growth factor receptor 2 gene (HER2/neu is overexpressed in 25%–30% of breast cancers. The current methods of detection for HER2 status, including immunohistochemistry and fluorescence in situ hybridization, are used ex vivo and cannot be used in vivo. In this paper, we demonstrate the application of near-infrared-emitting quantum dots for HER2 localization in fixed and live cancer cells as a first step prior to their in vivo application. Methods: Near-infrared-emitting quantum dots were characterized and their in vitro toxicity was established using three cancer cell lines, ie, HepG2, SK-BR-3 (HER2-overexpressing, and MCF7 (HER2-underexpressing. Mouse antihuman anti-HER2 monoclonal antibody was conjugated to the near-infrared-emitting quantum dots. Results: In vitro toxicity studies showed biocompatibility of SK-BR-3 and MCF7 cell lines with near-infrared-emitting quantum dots at a concentration of 60 µg/mL after one hour and 24 hours of exposure. Near-infrared-emitting quantum dot antiHER2-antibody bioconjugates successfully localized HER2 receptors on SK-BR-3 cells

  13. Charge State Hysteresis in Semiconductor Quantum Dots

    OpenAIRE

    Yang, C. H.; Rossi, A; Lai, N. S.; Leon, R.; Lim, W. H.; Dzurak, A.S.

    2014-01-01

    Semiconductor quantum dots provide a two-dimensional analogy for real atoms and show promise for the implementation of scalable quantum computers. Here, we investigate the charge configurations in a silicon metal-oxide-semiconductor double quantum dot tunnel coupled to a single reservoir of electrons. By operating the system in the few-electron regime, the stability diagram shows hysteretic tunnelling events that depend on the history of the dots charge occupancy. We present a model which acc...

  14. Resonant electron transfer between quantum dots

    OpenAIRE

    Openov, Leonid A.

    1999-01-01

    An interaction of electromagnetic field with a nanostructure composed of two quantum dots is studied theoretically. An effect of a resonant electron transfer between the localized low-lying states of quantum dots is predicted. A necessary condition for such an effect is the existence of an excited bound state whose energy lies close to the top of the barrier separating the quantum dots. This effect may be used to realize the reversible quantum logic gate NOT if the superposition of electron s...

  15. Optical Fiber Sensing Using Quantum Dots

    Directory of Open Access Journals (Sweden)

    Faramarz Farahi

    2007-12-01

    Full Text Available Recent advances in the application of semiconductor nanocrystals, or quantumdots, as biochemical sensors are reviewed. Quantum dots have unique optical properties thatmake them promising alternatives to traditional dyes in many luminescence basedbioanalytical techniques. An overview of the more relevant progresses in the application ofquantum dots as biochemical probes is addressed. Special focus will be given toconfigurations where the sensing dots are incorporated in solid membranes and immobilizedin optical fibers or planar waveguide platforms.

  16. Big Surveys, Big Data Centres

    Science.gov (United States)

    Schade, D.

    2016-06-01

    Well-designed astronomical surveys are powerful and have consistently been keystones of scientific progress. The Byurakan Surveys using a Schmidt telescope with an objective prism produced a list of about 3000 UV-excess Markarian galaxies but these objects have stimulated an enormous amount of further study and appear in over 16,000 publications. The CFHT Legacy Surveys used a wide-field imager to cover thousands of square degrees and those surveys are mentioned in over 1100 publications since 2002. Both ground and space-based astronomy have been increasing their investments in survey work. Survey instrumentation strives toward fair samples and large sky coverage and therefore strives to produce massive datasets. Thus we are faced with the "big data" problem in astronomy. Survey datasets require specialized approaches to data management. Big data places additional challenging requirements for data management. If the term "big data" is defined as data collections that are too large to move then there are profound implications for the infrastructure that supports big data science. The current model of data centres is obsolete. In the era of big data the central problem is how to create architectures that effectively manage the relationship between data collections, networks, processing capabilities, and software, given the science requirements of the projects that need to be executed. A stand alone data silo cannot support big data science. I'll describe the current efforts of the Canadian community to deal with this situation and our successes and failures. I'll talk about how we are planning in the next decade to try to create a workable and adaptable solution to support big data science.

  17. The Canadian Astronomy Data Centre

    Science.gov (United States)

    Ball, Nicholas M.; Schade, D.; Astronomy Data Centre, Canadian

    2011-01-01

    The Canadian Astronomy Data Centre (CADC) is the world's largest astronomical data center, holding over 0.5 Petabytes of information, and serving nearly 3000 astronomers worldwide. Its current data collections include BLAST, CFHT, CGPS, FUSE, Gemini, HST, JCMT, MACHO, MOST, and numerous other archives and services. It provides extensive data archiving, curation, and processing expertise, via projects such as MegaPipe, and enables substantial day-to-day collaboration between resident astronomers and computer specialists. It is a stable, powerful, persistent, and properly supported environment for the storage and processing of large volumes of data, a condition that is now absolutely vital for their science potential to be exploited by the community. Through initiatives such as the Common Archive Observation Model (CAOM), the Canadian Virtual Observatory (CVO), and the Canadian Advanced Network for Astronomical Research (CANFAR), the CADC is at the global forefront of advancing astronomical research through improved data services. The CAOM aims to provide homogeneous data access, and hence viable interoperability between a potentially unlimited number of different data collections, at many wavelengths. It is active in the definition of numerous emerging standards within the International Virtual Observatory, and several datasets are already available. The CANFAR project is an initiative to make cloud computing for storage and data-intensive processing available to the community. It does this via a Virtual Machine environment that is equivalent to managing a local desktop. Several groups are already processing science data. CADC is also at the forefront of advanced astronomical data analysis, driven by the science requirements of astronomers both locally and further afield. The emergence of 'Astroinformatics' promises to provide not only utility items like object classifications, but to directly enable new science by accessing previously undiscovered or intractable

  18. Activation of silicon quantum dots for emission

    Institute of Scientific and Technical Information of China (English)

    Huang Wei-Qi; Miao Xin-Jian; Huang Zhong-Mei; Liu Shi-Rong; Qin Chao-Jian

    2012-01-01

    The emission of silicon quantum dots is weak when their surface is passivated well. Oxygen or nitrogen on the surface of silicon quantum dots can break the passivation to form localized electronic states in the band gap to generate active centers where stronger emission occurs.From this point of view,we can build up radiative matter for emission.Emissions of various wavelengths can be obtained by controlling the surface bonds of silicon quantum dots.Our experimental results demonstrate that annealing is important in the treatment of the activation,and stimulated emissions at about 600 and 700 nm take place on active silicon quantum dots.

  19. Thermoelectric energy harvesting with quantum dots.

    Science.gov (United States)

    Sothmann, Björn; Sánchez, Rafael; Jordan, Andrew N

    2015-01-21

    We review recent theoretical work on thermoelectric energy harvesting in multi-terminal quantum-dot setups. We first discuss several examples of nanoscale heat engines based on Coulomb-coupled conductors. In particular, we focus on quantum dots in the Coulomb-blockade regime, chaotic cavities and resonant tunneling through quantum dots and wells. We then turn toward quantum-dot heat engines that are driven by bosonic degrees of freedom such as phonons, magnons and microwave photons. These systems provide interesting connections to spin caloritronics and circuit quantum electrodynamics.

  20. POLARON IN CYLINDRICAL AND SPHERICAL QUANTUM DOTS

    Directory of Open Access Journals (Sweden)

    L.C.Fai

    2004-01-01

    Full Text Available Polaron states in cylindrical and spherical quantum dots with parabolic confinement potentials are investigated applying the Feynman variational principle. It is observed that for both kinds of quantum dots the polaron energy and mass increase with the increase of Frohlich electron-phonon coupling constant and confinement frequency. In the case of a spherical quantum dot, the polaron energy for the strong coupling is found to be greater than that of a cylindrical quantum dot. The energy and mass are found to be monotonically increasing functions of the coupling constant and the confinement frequency.

  1. Semiconductor quantum-dot lasers and amplifiers

    DEFF Research Database (Denmark)

    Hvam, Jørn Märcher; Borri, Paola; Ledentsov, N. N.;

    2002-01-01

    -power surface emitting VCSELs. We investigated the ultrafast dynamics of quantum-dot semiconductor optical amplifiers. The dephasing time at room temperature of the ground-state transition in semiconductor quantum dots is around 250 fs in an unbiased amplifier, decreasing to below 50 fs when the amplifier...... is biased to positive net gain. We have further measured gain recovery times in quantum dot amplifiers that are significantly lower than in bulk and quantum-well semiconductor optical amplifiers. This is promising for future demonstration of quantum dot devices with high modulation bandwidth...

  2. Sensitisation of visible and NIR lanthanide emission by InPZnS quantum dots in bi-luminescent hybrids.

    Science.gov (United States)

    Molloy, Jennifer K; Lincheneau, Christophe; Karimdjy, Maria Moula; Agnese, Fabio; Mattera, Lucia; Gateau, Christelle; Reiss, Peter; Imbert, Daniel; Mazzanti, Marinella

    2016-03-25

    The synthesis of stable hybrid nanoparticles combining InPZnS@ZnSe/ZnS quantum dots (QDs) and grafted lanthanide complexes has been performed using two different approaches in organic and aqueous media. The final bi-luminescent hybrids exhibit Ln(III) (Ln = Eu and Yb) centred luminescence upon QD excitation, suggesting that an energy transfer occurs from the QD to the lanthanide. PMID:26941180

  3. Synthesis and application of luminescent single CdS quantum dot encapsulated silica nanoparticles directed for precision optical bioimaging

    OpenAIRE

    Veeranarayanan S; Poulose AC; Mohamed MS; Nagaoka Y; Iwai S.; Nakagame Y; Kashiwada S; Yoshida Y; Maekawa T; Kumar DS

    2012-01-01

    Srivani Veeranarayanan, Aby Cheruvathoor Poulose, M Sheikh Mohamed, Yutaka Nagaoka, Seiki Iwai, Yuya Nakagame, Shosaku Kashiwada, Yasuhiko Yoshida, Toru Maekawa, D Sakthi KumarBio Nano Electronics Research Centre, Graduate School of Interdisciplinary New Science, Toyo University, Kawagoe, JapanAbstract: This paper presents the synthesis of aqueous cadmium sulfide (CdS) quantum dots (QDs) and silica-encapsulated CdS QDs by reverse microemulsion method and utilized as targeted bio-optical probe...

  4. From micro- to nanomagnetic dots: evolution of the eigenmode spectrum on reducing the lateral size

    Science.gov (United States)

    Carlotti, G.; Gubbiotti, G.; Madami, M.; Tacchi, S.; Hartmann, F.; Emmerling, M.; Kamp, M.; Worschech, L.

    2014-07-01

    Brillouin light scattering experiments and micromagnetic simulations have been exploited to investigate the spectrum of thermally excited magnetic eigenmodes in 10 nm-thick elliptical Permalloy dots, when the longer axis D is scaled down from about 1000 to 100 nm. It is shown that for D larger than about 200 nm the characteristics of the spin-wave eigenmodes are dominated by dipolar energy, while for D in the range of about 100 to 200 nm exchange energy effects cause qualitative and quantitative differences in the spin-wave spectrum. In this ‘mesoscopic’ regime, the usual classification scheme, involving one fundamental mode with large average magnetization and many other modes collected in families with specific symmetries, no longer holds. Rather, one finds the simultaneous presence of two modes with ‘fundamental’ character, i.e. with a significant and comparable value of the average dynamical magnetization: the former is at larger frequency and has its maximum amplitude at the dot's centre, while the latter occurs at lower frequency and is localized at the dot's edges. Interestingly, the maximum intensity swaps from the higher frequency mode to the lower frequency one, just when the dot size is reduced from about 200 to 100 nm. This is relevant in view of the exploitation of nanodots for the design of nanomagnetic devices with lateral dimensions in the above interval, such as memory cells, logic gates, reading heads and spin-torque oscillators.

  5. Review of CERN Data Centre Infrastructure

    CERN Document Server

    Andrade, P; van Eldik, J; McCance, G; Panzer-Steindel, B; Coelho dos Santos, M; Traylen, S; Schwickerath, U

    2012-01-01

    The CERN Data Centre is reviewing strategies for optimizing the use of the existing infrastructure and expanding to a new data centre by studying how other large sites are being operated. Over the past six months, CERN has been investigating modern and widely-used tools and procedures used for virtualisation, clouds and fabric management in order to reduce operational effort, increase agility and support unattended remote data centres. This paper gives the details on the project’s motivations, current status and areas for future investigation.

  6. Review of CERN Data Centre Infrastructure

    Science.gov (United States)

    Andrade, P.; Bell, T.; van Eldik, J.; McCance, G.; Panzer-Steindel, B.; Coelho dos Santos, M.; Traylen and, S.; Schwickerath, U.

    2012-12-01

    The CERN Data Centre is reviewing strategies for optimizing the use of the existing infrastructure and expanding to a new data centre by studying how other large sites are being operated. Over the past six months, CERN has been investigating modern and widely-used tools and procedures used for virtualisation, clouds and fabric management in order to reduce operational effort, increase agility and support unattended remote data centres. This paper gives the details on the project's motivations, current status and areas for future investigation.

  7. Quantum Dot Spectrum Converters for Enhanced High Efficiency Photovoltaics Project

    Data.gov (United States)

    National Aeronautics and Space Administration — This research proposes to enhance solar cell efficiency, radiation resistance and affordability. The Quantum Dot Spectrum Converter (QDSC) disperses quantum dots...

  8. Towards Human-Centred Design

    Science.gov (United States)

    Bannon, Liam J.

    The field of HCI has evolved and expanded dramatically since its origin in the early 1980’s. The HCI community embraces a large community of researchers and practitioners around the world, from a variety of disciplinary backgrounds in the human and social sciences, engineering and informatics, and more recently, the arts and design disciplines. This kaleidoscope of cultures and disciplines as seen at INTERACT Conferences provides a rich pool of resources for examining our field. Applications are increasingly exploring our full range of sensory modalities, and merging the digital and physical worlds. WiFi has opened up a huge design space for mobile applications. A focus on usability of products and services has been complemented by an emphasis on engagement, enjoyment and experience. With the advent of ubiquitous computing, and the emergence of “The Internet of Things”, new kinds of more open infrastructures make possible radically new kinds of applications. The sources of innovation have also broadened, to include human and social actors outside of the computing and design organizations. The question is to what extent is our mainstream thinking in the HCI field ready for the challenges of this Brave New World? Do the technological and social innovations that we see emerging require us to re-shape, or even, re-create, our field, or is it a case of a more gradual evolution and development of that which we already know? In this closing Keynote, I will provide a perspective on the evolution and development of the HCI field, looking backwards as well as forwards, in order to determine what are some of the changes of significance in the field. This “broad-brush” approach to what I term “ human-centred design” will be complemented by the examination of specific projects and applications, to help anchor some of the discussion. Areas such as user-centred design, participatory design, computer-supported cooperative work and learning, and interaction design, in

  9. Quantum Gates Between Two Spins in a Triple Dot System with an Empty Dot

    CERN Document Server

    Coello, Jose Garcia

    2011-01-01

    We propose a scheme for implementing quantum gates and entanglement between spin qubits in the outer dots of a triple-dot system with an empty central dot. The voltage applied to the central dot can be tuned to realize the gate. Our scheme exemplifies the possibility of quantum gates outside the regime where each dot has an electron, so that spin-spin exchange interaction is not the only relevant mechanism. Analytic treatment is possible by mapping the problem to a t-J model. The fidelity of the entangling quantum gate between the spins is analyzed in the presence of decoherence stemming from a bath of nuclear spins, as well as from charge fluctuations. Our scheme provides an avenue for extending the scope of two qubit gate experiments to triple-dots, while requiring minimal control, namely that of the potential of a single dot, and may enhance the qubit separation to ease differential addressability.

  10. Nitrogen-Doped Carbon Dots for "green" Quantum Dot Solar Cells.

    Science.gov (United States)

    Wang, Hao; Sun, Pengfei; Cong, Shan; Wu, Jiang; Gao, Lijun; Wang, Yun; Dai, Xiao; Yi, Qinghua; Zou, Guifu

    2016-12-01

    Considering the environment protection, "green" materials are increasingly explored for photovoltaics. Here, we developed a kind of quantum dots solar cell based on nitrogen-doped carbon dots. The nitrogen-doped carbon dots were prepared by direct pyrolysis of citric acid and ammonia. The nitrogen-doped carbon dots' excitonic absorption depends on the N-doping content in the carbon dots. The N-doping can be readily modified by the mass ratio of reactants. The constructed "green" nitrogen-doped carbon dots solar cell achieves the best power conversion efficiency of 0.79 % under AM 1.5 G one full sun illumination, which is the highest efficiency for carbon dot-based solar cells. PMID:26781285

  11. Symmetric centres of braided monoidal categories

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    This paper introduces the concept of‘symmetric centres' of braided monoidal categories. Let H be a Hopf algebra with bijective antipode over a field k. We address the symmetric centre of the Yetter-Drinfel'd module category HH(yD) and show that a left Yetter-Drinfel'd module M belongs to the symmetric centre of HH(yD) if and only if M is trivial. We also study the symmetric centres of categories of representations of quasitriangular Hopf algebras and give a sufficient and necessary condition for the braid of H(M) to induce the braid of (H(H)(A),(○)A,A,φ,l,r), or equivalently, the braid of (A#H(H),(○)A,A,φ,l,r), where A is a quantum commutative H-module algebra.

  12. Photoinduced electron transfers with carbon dots

    OpenAIRE

    Wang, Xin; Cao, Li; Lu, Fushen; Meziani, Mohammed J.; Li, Heting; Qi, Gang; Zhou, Bing; Harruff, Barbara A.; Kermarrec, Fabien; Sun, Ya-Ping

    2009-01-01

    The photoluminescence in carbon dots (surface-passivated small carbon nanoparticles) could be quenched efficiently by electron acceptor or donor molecules in solution, namely that photo-excited carbon dots are both excellent electron donors and excellent electron acceptors, thus offering new opportunities for their potential uses in light energy conversion and related applications.

  13. Thick-shell nanocrystal quantum dots

    Science.gov (United States)

    Hollingsworth, Jennifer A.; Chen, Yongfen; Klimov, Victor I.; Htoon, Han; Vela, Javier

    2011-05-03

    Colloidal nanocrystal quantum dots comprising an inner core having an average diameter of at least 1.5 nm and an outer shell, where said outer shell comprises multiple monolayers, wherein at least 30% of the quantum dots have an on-time fraction of 0.80 or greater under continuous excitation conditions for a period of time of at least 10 minutes.

  14. Optical Properties of Semiconductor Quantum Dots

    NARCIS (Netherlands)

    Perinetti, U.

    2011-01-01

    This thesis presents different optical experiments performed on semiconductor quantum dots. These structures allow to confine a small number of electrons and holes to a tiny region of space, some nm across. The aim of this work was to study the basic properties of different types of quantum dots mad

  15. Detecting the chirality for coupled quantum dots

    Energy Technology Data Exchange (ETDEWEB)

    Cao Huijuan [Institute for Condensed Matter Physics, School of Physics and Telecommunication Engineering, South China Normal University, Guangzhou 510631 (China); Hu Lian [Institute for Condensed Matter Physics, School of Physics and Telecommunication Engineering, South China Normal University, Guangzhou 510631 (China)], E-mail: huliancaohj@yahoo.com

    2008-04-21

    We propose a scheme to detect the chirality for a system consisting of three coupled quantum dots. The chirality is found to be determined by the frequency of the transition between chiral states under the chiral symmetry broken perturbation. The results are important to construct quantum gates and to demonstrate chiral entangle states in the triangle spin dots.

  16. Double Acceptor Interaction in Semimagnetic Quantum Dot

    Directory of Open Access Journals (Sweden)

    A. Merwyn Jasper D. Reuben

    2011-01-01

    Full Text Available The effect of geometry of the semimagnetic Quantum Dot on the Interaction energy of a double acceptor is computed in the effective mass approximation using the variational principle. A peak is observed at the lower dot sizes as a magnetic field is increased which is attributed to the reduction in confinement.

  17. The relativistic two-centre continuum

    International Nuclear Information System (INIS)

    A method is presented to define unique continuum states for the two-centre Dirac Hamiltonian. In the spherical limit these states become the familiar angular momentum eigenstates of the radial Coulomb potential. The different states for a fixed total energy vertical strokeEvertical stroke > m may be distinguished by considering the asymptotic spin-angular distribution of states with unique scattering-phases. First numerical solutions of the two-centre Dirac equation for continuum states are presented. (orig.)

  18. INFOTERM – Information Disseminating Centre for Terminology

    OpenAIRE

    Albina Auksoriūtė

    2014-01-01

    International Information Centre for Terminology (INFOTERM) was founded in 1971 by contract with the United Nations Educational, Scientific and Cultural Organization (UNESCO) and the Austrian Standards Institute (ASI). In 1996, INFOTERM was reorganized and established as an independent non-profit organization. INFOTERM promotes and supports the cooperation of existing and the establishment of new terminology centres and networks with the general aim to improve domain communication, knowledge ...

  19. Two centre problems in relativistic atomic physics

    OpenAIRE

    McConnell, Sean R.

    2012-01-01

    The work contained within this thesis is concerned with the explanation and usage of a set of theoretical procedures for the study of static and dynamic two–centre problems in the relativistic framework of Dirac’s equation. Two distinctly different theories for handling time–dependent atomic interactions are reviewed, namely semi–classical perturbation theory and a non–perturbative numerical technique based on the coupled channel equation to directly solve the time–dependent, two–centre Dirac...

  20. Joint Research Centre. Ispra establishment-Italy

    International Nuclear Information System (INIS)

    A comprehensive review of the work carried out during 1974 and 1975 in the Ispra establishment of the Joint Research Centre is presented. A description of the activity carried out within the context of the running programmes is given. Some of the most relevant scientific and technical achievement are described from the viewpoints of the Scientific Departments of the Centre. The technical and administrative support activities are also presented. A list of publications issued by the Ispra Scientific staff is given

  1. Social innovation for People-Centred Development

    DEFF Research Database (Denmark)

    Hulgård, Lars; P.K., Shajahan

    2013-01-01

    Social innovation is closely related to the people-centred development (PCD) framework of knowledge production. The discussion of PCD in this chapter particularly expands on the feature of empowerment and socio-political mobilization of people in social innovation......Social innovation is closely related to the people-centred development (PCD) framework of knowledge production. The discussion of PCD in this chapter particularly expands on the feature of empowerment and socio-political mobilization of people in social innovation...

  2. Perspectives on recycling centres and future developments.

    Science.gov (United States)

    Engkvist, I-L; Eklund, J; Krook, J; Björkman, M; Sundin, E

    2016-11-01

    The overall aim of this paper is to draw combined, all-embracing conclusions based on a long-term multidisciplinary research programme on recycling centres in Sweden, focussing on working conditions, environment and system performance. A second aim is to give recommendations for their development of new and existing recycling centres and to discuss implications for the future design and organisation. Several opportunities for improvement of recycling centres were identified, such as design, layout, ease with which users could sort their waste, the work environment, conflicting needs and goals within the industry, and industrialisation. Combining all results from the research, which consisted of different disciplinary aspects, made it possible to analyse and elucidate their interrelations. Waste sorting quality was recognized as the most prominent improvement field in the recycling centre system. The research identified the importance of involving stakeholders with different perspectives when planning a recycling centre in order to get functionality and high performance. Practical proposals of how to plan and build recycling centres are given in a detailed checklist. PMID:26826952

  3. Medication errors: pharmacovigilance centres in detection and prevention

    OpenAIRE

    Bencheikh, Rachida Soulaymani; Benabdallah, Ghita

    2009-01-01

    Detecting medication errors needs collaboration between various organizations, such as patient safety institutions, pharmacovigilance centres, and poison control centres. In order to evaluate the input of pharmacovigilance centres and poison control centres in detecting and evaluating medication errors a pilot project was initiated by the World Alliance for Patient Safety in collaboration with the Uppsala Monitoring Centre; the Moroccan pharmacovigilance centre acted as project coordinator. A...

  4. Model-based clustered-dot screening

    Science.gov (United States)

    Kim, Sang Ho

    2006-01-01

    I propose a halftone screen design method based on a human visual system model and the characteristics of the electro-photographic (EP) printer engine. Generally, screen design methods based on human visual models produce dispersed-dot type screens while design methods considering EP printer characteristics generate clustered-dot type screens. In this paper, I propose a cost function balancing the conflicting characteristics of the human visual system and the printer. By minimizing the obtained cost function, I design a model-based clustered-dot screen using a modified direct binary search algorithm. Experimental results demonstrate the superior quality of the model-based clustered-dot screen compared to a conventional clustered-dot screen.

  5. Substitutional impurity in the graphene quantum dots

    Science.gov (United States)

    Sierański, K.; Szatkowski, J.

    2015-09-01

    The process of formation of the localized defect states due to substitutional impurity in sp2-bonded graphene quantum dot is considered using a simple tight-binding-type calculation. We took into account the interaction of the quantum dot atoms surrounding the substitutional impurity from the second row of elements. To saturate the external dangling sp2 orbitals of the carbon additionally 18 hydrogen atoms were introduced. The chemical formula of the quantum dot is H18C51X, where X is the symbol of substitutional atom. The position of the localized levels is determined relative to the host-atoms (C) εp energies. We focused on the effect of substitutional doping by the B, N and O on the eigenstate energies and on the total energy change of the graphene dots including for O the effect of lattice distorsion. We conclude that B, N, and O can form stable substitutional defects in graphene quantum dot.

  6. Electron transport in quantum dots

    CERN Document Server

    2003-01-01

    When I was contacted by Kluwer Academic Publishers in the Fall of 200 I, inviting me to edit a volume of papers on the issue of electron transport in quantum dots, I was excited by what I saw as an ideal opportunity to provide an overview of a field of research that has made significant contributions in recent years, both to our understanding of fundamental physics, and to the development of novel nanoelectronic technologies. The need for such a volume seemed to be made more pressing by the fact that few comprehensive reviews of this topic have appeared in the literature, in spite of the vast activity in this area over the course of the last decade or so. With this motivation, I set out to try to compile a volume that would fairly reflect the wide range of opinions that has emerged in the study of electron transport in quantum dots. Indeed, there has been no effort on my part to ensure any consistency between the different chapters, since I would prefer that this volume instead serve as a useful forum for the...

  7. Transmission of HIV in dialysis centre.

    Science.gov (United States)

    Velandia, M; Fridkin, S K; Cárdenas, V; Boshell, J; Ramirez, G; Bland, L; Iglesias, A; Jarvis, W

    1995-06-01

    In August, 1993, 13 dialysis patients at one dialysis centre in Colombia, South America, were found to be HIV positive, and this prompted an epidemiological investigation. We carried out a cohort study of all dialysis centre patients during January, 1992 to December, 1993 (epidemic period) to determine risk factors for HIV seroconversion. Haemodialysis and medical records were reviewed, dialysis centre staff and surviving patients were interviewed, and dialysis practices were observed. Stored sera from all dialysis centre patients were tested for HIV antibody. 12 (52%) of 23 patients tested positive for HIV antibody by enzyme immunoassay and western blot during the epidemic period. Of the 23 tested, 9 (39%) converted from HIV antibody negative to positive (seroconverters) and 10 (44%) remained HIV negative (seronegatives). The HIV seroconversion rate was higher among patients dialysed at the centre while a new patient, who was HIV seropositive, was dialysed there (90% vs 0%; p dialysis centre reprocessed access needles, dialysers, and bloodlines (60% vs 0%). While 2 of 9 HIV seroconverters had had sex with prostitutes, none had received unscreened blood products or had other HIV risk factors. No surgical or dental procedures were associated with HIV seroconversion. Dialysers were reprocessed separately with 5% formaldehyde and were labelled for use on the same patient. Access needles were reprocessed by soaking them in a common container with a low-level disinfectant, benzalkonium chloride; 4 pairs of needles were placed in one pan creating the potential for cross-contamination or use of one patient's needles on another patient. HIV transmission at the dialysis centre was confirmed. Improperly reprocessed patient-care equipment, most probably access needles, is the likely mechanism of transmission. This outbreak was discovered by accident and similar transmission may be occurring in many other countries where low-level disinfectants are used to sterilise critical

  8. Scavenger hunt in the CERN Computing Centre

    CERN Multimedia

    CERN Bulletin

    2013-01-01

    Hidden among the racks of servers and disks in the CERN Computing Centre, you’ll find Hawaiian dancers, space aliens, gorillas… all LEGO® figurines! These characters were placed about the Centre for the arrival of Google’s Street View team for the world to discover.   PLEASE NOTE THAT THE COMPETITION IS OVER. ONLY FOR REFERENCE, HERE IS THE ORIGINAL ARTICLE. We’re pleased to announce our first global scavenger hunt! Spot three LEGO® figurines using Google’s Street View and you’ll be entered to win a gift of your choice from our CERN Gift Guide. A LEGO® figurine in the CERN Computing Centre, as seen on Google Street View. Here are the details: Find at least three LEGO® figurines hidden around the CERN Computing Centre using Google Street View.   Take screencaps of the figurines and e-mail the pictures to TreasureHunt-ComputingCentre@cern.ch. This email is no longer active.   The...

  9. Visits to Tier-1 Computing Centres

    CERN Multimedia

    Dario Barberis

    At the beginning of 2007 it became clear that an enhanced level of communication is needed between the ATLAS computing organisation and the Tier-1 centres. Most usual meetings are ATLAS-centric and cannot address the issues of each Tier-1; therefore we decided to organise a series of visits to the Tier-1 centres and focus on site issues. For us, ATLAS computing management, it is most useful to realize how each Tier-1 centre is organised, and its relation to the associated Tier-2s; indeed their presence at these visits is also very useful. We hope it is also useful for sites... at least, we are told so! The usual participation includes, from the ATLAS side: computing management, operations, data placement, resources, accounting and database deployment coordinators; and from the Tier-1 side: computer centre management, system managers, Grid infrastructure people, network, storage and database experts, local ATLAS liaison people and representatives of the associated Tier-2s. Visiting Tier-1 centres (1-4). ...

  10. The Aube centre. 1997 statement; Le centre de l`Aube. Bilan 1997

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1998-09-01

    Since January 1992 the Aube centre ensures the storage of 90% of the short life radioactive wastes produced in France. This educational booklet describes the organization of the activities in the centre from the storage of wastes to the radioactivity surveillance of the environment (air, surface and ground waters, river sediments, plants and milk). (J.S.)

  11. Quantum Dots Investigated for Solar Cells

    Science.gov (United States)

    Bailey, Sheila G.; Castro, Stephanie L.; Raffaelle, Ryne P.; Hepp, Aloysius F.

    2001-01-01

    The NASA Glenn Research Center has been investigating the synthesis of quantum dots of CdSe and CuInS2 for use in intermediate-bandgap solar cells. Using quantum dots in a solar cell to create an intermediate band will allow the harvesting of a much larger portion of the available solar spectrum. Theoretical studies predict a potential efficiency of 63.2 percent, which is approximately a factor of 2 better than any state-of-the-art devices available today. This technology is also applicable to thin-film devices--where it offers a potential four-fold increase in power-to-weight ratio over the state of the art. Intermediate-bandgap solar cells require that quantum dots be sandwiched in an intrinsic region between the photovoltaic solar cell's ordinary p- and n-type regions (see the preceding figure). The quantum dots form the intermediate band of discrete states that allow sub-bandgap energies to be absorbed. However, when the current is extracted, it is limited by the bandgap, not the individual photon energies. The energy states of the quantum dot can be controlled by controlling the size of the dot. Ironically, the ground-state energy levels are inversely proportional to the size of the quantum dots. We have prepared a variety of quantum dots using the typical organometallic synthesis routes pioneered by Ba Wendi et al., in the early 1990's. The most studied quantum dots prepared by this method have been of CdSe. To produce these dots, researchers inject a syringe of the desired organometallic precursors into heated triocytlphosphine oxide (TOPO) that has been vigorously stirred under an inert atmosphere (see the following figure). The solution immediately begins to change from colorless to yellow, then orange and red/brown, as the quantum dots increase in size. When the desired size is reached, the heat is removed from the flask. Quantum dots of different sizes can be identified by placing them under a "black light" and observing the various color differences in

  12. Fluorescent Quantum Dots for Biological Labeling

    Science.gov (United States)

    McDonald, Gene; Nadeau, Jay; Nealson, Kenneth; Storrie-Lomardi, Michael; Bhartia, Rohit

    2003-01-01

    Fluorescent semiconductor quantum dots that can serve as "on/off" labels for bacteria and other living cells are undergoing development. The "on/off" characterization of these quantum dots refers to the fact that, when properly designed and manufactured, they do not fluoresce until and unless they come into contact with viable cells of biological species that one seeks to detect. In comparison with prior fluorescence-based means of detecting biological species, fluorescent quantum dots show promise for greater speed, less complexity, greater sensitivity, and greater selectivity for species of interest. There are numerous potential applications in medicine, environmental monitoring, and detection of bioterrorism.

  13. Time-bin Entanglement from Quantum Dots

    CERN Document Server

    Weihs, Gregor; Predojević, Ana

    2016-01-01

    The desire to have a source of single entangled photon pairs can be satisfied using single quantum dots as emitters. However, we are not bound to pursue only polarization entanglement, but can also exploit other degrees of freedom. In this chapter we focus on the time degree of freedom, to achieve so-called time-bin entanglement. This requires that we prepare the quantum dot coherently into the biexciton state and also build special interferometers for analysis. Finally this technique can be extended to achieve time-bin and polarization hyper-entanglement from a suitable quantum dot.

  14. Learning Styles of Independent Learning Centre Users

    Directory of Open Access Journals (Sweden)

    Tarik Uzun

    2014-09-01

    Full Text Available Learning style research has been a significant field within language teaching and learning. There have been very few attempts, however, to seek possible links between independent learning and learning style preferences. This paper aims to identify the learning styles of students who use the Independent Learning Centre (ILC on a regular basis at a state university in Turkey (n=102. The findings of the learning style analysis revealed that, contrary to expectations, most of the regular users of the centre were synoptic learners, which implies that these learners might not necessarily have conscious control over their own learning processes. An in-depth analysis of learning styles and recommendations to improve the services offered in the centre are also included in the paper.

  15. Occupational deprivation in an asylum centre:

    DEFF Research Database (Denmark)

    Morville, Anne-Le; Erlandsson, Lena-Karin

    2013-01-01

    This article presents a study of three asylum-seeking men from Iran and Afghanistan. It aimed to explore how and if they experienced occupations as occupations in a Danish asylum centre and how their life experience shaped their choice and value of current occupations. In-depth narrative interviews...... explored the participants’ occupational history and its influence on their occupations in the asylum centre. A thematic analysis showed that the participants had been subjected to occupational disruption and deprivation by politically oppressive systems even before their flight. Their occupations...... in Denmark were to a certain extent influenced by their earlier occupations and the current occupational deprivation they all experienced was due to limited possibilities in the centre. Although they tried their best to fill their days and create structure, there was a loss of valued occupations...

  16. A day in the CERN Control Centre

    CERN Multimedia

    Rosaria Marraffino

    2015-01-01

    The CERN Control Centre (CCC) is the nerve centre of the CERN beam systems. From this room, the experts prepare, monitor, adjust, and control the particle beams that circulate throughout the accelerator complex while ensuring that the services and the technical infrastructure work flawlessly. Buttons, screens, telephones, lights (but no sound): in the CCC, everything is ready to make it possible for the LHC to reach the unprecedented energies expected at Run 2.   Seen from above, the CERN Control Centre resembles the shape of a quadrupole magnet. The consoles are distributed in four circles, called “islands”, dedicated to the LHC, the SPS, the PS Complex and the Technical Infrastructure (TI) respectively. Spread between TI and LHC are the Cryogenics consoles. Being in the same room allows the 24h-manned islands to be constantly in touch with one another, thus ensuring the best performance of the machines. At the LHC island, operators are currently busy training the magnet...

  17. Enhancing person-centred communication in NICU

    DEFF Research Database (Denmark)

    Weis, Janne; Zoffmann, Vibeke; Egerod, Ingrid

    2015-01-01

    Aims of this article were (a) to explore how parents of premature infants experience guided family-centred care (GFCC), and (b) to compare how parents receiving GFCC versus standard care (SC) describe nurse-parent communication in the neonatal intensive care unit.......Aims of this article were (a) to explore how parents of premature infants experience guided family-centred care (GFCC), and (b) to compare how parents receiving GFCC versus standard care (SC) describe nurse-parent communication in the neonatal intensive care unit....

  18. Imperial College Reactor Centre annual report. 1984

    International Nuclear Information System (INIS)

    The following new equipment is noted; for atomic absorption spectrometry to supplement the neutron activation analysis, and an additional nuclear data analysis system to improve the quality and speed of the service to users of the Centre's facilities. Users include undergraduates from the University of London, outside bodies such as the British Musueum, as well as departments of Colleges of the University of London. The reactor lost only three days through failures or faults. Two replacement fuel elements were put into the reactor during the year. The report contains brief accounts of 34 research programmes at the Centre. (U.K.)

  19. A study on socio-demographic profile and feasibility of DOTS provider registered under RNTCP in Varanasi district Uttar Pradesh

    Directory of Open Access Journals (Sweden)

    Mohd. Afzalul Haque

    2014-03-01

    Full Text Available Introduction: Tuberculosis is a major chronic disorder affecting the larger population more than any other disease in the country. DOTS was introduced in India in 1993 as part of the Revised National Tuberculosis Programme (RNTCP following a review of India’s National Tuberculosis Programme (NTP a year earlier (1 .Patient satisfaction is an important parameter for assessing the quality of patient care services. There is need to assess the health care provider regarding the consumer satisfaction as often as possible, this paper summarizes our experience about role of DOTS provider in the management of TB patient in rural population of Varanasi districts Utter Pradesh. Objective: (1 To assess the perception of registered tuberculosis patients regarding DOTS provider for the treatment of tuberculosis. (2 To assess the accessibility, acceptability & availability of community DOTS provider. Design: A longitudinal study. Setting: Three microscopic centre of Cholapur Tuberculosis unit of Varanasi districts. Methods: Registered patients were interviewed twice: once in the beginning and another at the completion of the treatment or after the permanent discontinuation of the treatment. Patients were interviewed for their socio-demographic profiles, opinion about DOTS and its providers. Side effects experienced and action taken etc. Data was collected on a semi-structured, pre-tested questionnaire. DOTS providers were interviewed and treatment cards analyzed for any interruption of treatment and action taken. Data was collected from 1st June 2004 to 31th June 2005 till the completion of the regimen. Results: Majority of DOTS providers were young males (82.7% of 26 years to 40 years, while the representation of females was only 5 (17.3%. Almost more than 80% of the patients started their treatment within 1-10 days. For majority of cases (83% the distance of DOTS provider from patient’s house was within 1 km. Mean time spent to go to DOTS provider was 27

  20. An evaluation of the dot-ELISA procedure as a diagnostic test in an area with a high prevalence of human Toxocara canis infection

    Directory of Open Access Journals (Sweden)

    María V Bojanich

    2012-03-01

    Full Text Available The aim of this work was to evaluate a dot-enzyme-linked immunosorbent assay (dot-ELISA using excretory-secretory antigens from the larval stages of Toxocara canis for the diagnosis of toxocariasis. A secondary aim was to establish the optimal conditions for its use in an area with a high prevalence of human T. canis infection. The dot-ELISA test was standardised using different concentrations of the antigen fixed on nitrocellulose paper strips and increasing dilutions of the serum and conjugate. Both the dot-ELISA and standard ELISA methods were tested in parallel with the same batch of sera from controls and from individuals living in the problem area. The best results were obtained with 1.33 µg/mL of antigen, dilutions of 1/80 for the samples and controls and a dilution of 1/5,000 for the anti-human IgG-peroxidase conjugate. All steps of the procedure were performed at room temperature. The coincidence between ELISA and dot-ELISA was 85% and the kappa index was 0.72. The dot-ELISA test described here is rapid, easy to perform and does not require expensive equipment. Thus, this test is suitable for the serological diagnosis of human T. canis infection in field surveys and in the primary health care centres of endemic regions.

  1. Large quantum dots with small oscillator strength

    DEFF Research Database (Denmark)

    Stobbe, Søren; Schlereth, T.W.; Höfling, S.;

    2010-01-01

    We have measured the oscillator strength and quantum efficiency of excitons confined in large InGaAs quantum dots by recording the spontaneous emission decay rate while systematically varying the distance between the quantum dots and a semiconductor-air interface. The size of the quantum dots...... is measured by in-plane transmission electron microscopy and we find average in-plane diameters of 40 nm. We have calculated the oscillator strength of excitons of that size assuming a quantum-dot confinement given by a parabolic in-plane potential and a hard-wall vertical potential and predict a very large...... oscillator strength due to Coulomb effects. This is in stark contrast to the measured oscillator strength, which turns out to be so small that it can be described by excitons in the strong confinement regime. We attribute these findings to exciton localization in local potential minima arising from alloy...

  2. Ge Quantum Dot Infrared Imaging Camera Project

    Data.gov (United States)

    National Aeronautics and Space Administration — Luna Innovations Incorporated proposes to develop a high performance Ge quantum dots-based infrared (IR) imaging camera on Si substrate. The high sensitivity, large...

  3. Spin current in double quantum dot

    Institute of Scientific and Technical Information of China (English)

    Zhao Hua; Zhang Guo-Feng; Yin Wen; Liang Jiu-Qing

    2004-01-01

    We have studied the dynamical behaviours of two electrons confined in a double quantum dot driven by rotating magnetic fields in terms of the theory of Lewis-Riesenfeld Hermitian invariants for the explicitly time-dependent Hamiltonian. The coherent spin oscillations in the dot provide a generation source for spin current. Exact solutions obtained allow us to investigate the dynamical properties of the spin localization for various initial localized states.

  4. Magnetic quantum dots and magnetic edge states

    International Nuclear Information System (INIS)

    Starting with defining the magnetic edge state in a magnetic quantum dot, which becomes quite popular nowadays conjunction with a possible candidate for a high density memory device or spintronic materials, various magnetic nano-quantum structures are reviewed in detail. We study the magnetic edge states of the two dimensional electron gas in strong perpendicular magnetic fields. We find that magnetic edge states are formed along the boundary of the magnetic dot, which is formed by a nonuniform distribution of magnetic fields. These magnetic edge states circulate either clockwise or counterclockwise, depending on the number of missing flux quanta, and exhibit quite different properties, as compared to the conventional ones which are induced by electrostatic confinements in the quantum Hall system. We also find that a close relation between the quantum mechanical eigenstates and the classical trajectories in the magnetic dot. When a magnetic dot is located inside a quantum wire, the edge-channel scattering mechanism by the magnetic quantum dot is very different from that by electrostatic dots. Here, the magnetic dot is formed by two different magnetic fields inside and outside the dot. We study the ballistic edge-channel transport and magnetic edge states in this situation. When the inner field is parallel to the outer one, the two-terminal conductance is quantized and shows the features of a transmission barrier and a resonator. On the other hand, when the inner field is reversed, the conductance is not quantized and all channels can be completely reflected in some energy ranges. The difference between the above two cases results from the distinct magnetic confinements. We also describe successfully the edge states of magnetic quantum rings and others in detail

  5. Coherent scattering in a small quantum dot

    International Nuclear Information System (INIS)

    Ballistic transport in an open small (100 nm) three-terminal quantum dot based on the high-mobility two-dimensional electron gas of the AlGaAs/GaAs heterojunction has been analyzed. It has been shown that the gate oscillations of resistance of such a dot arise due to the coherent scattering of electrons on its quasidiscrete levels being suppressed by a weak magnetic field

  6. Exploring Extragalactic Emission: The Hα Dot Survey

    Science.gov (United States)

    Rampalli, Rayna; Salzer, John Joseph

    2016-01-01

    The Hα Dot Survey was established as a result of finding point sources of strong line emission in the data obtained for the ALFALFA Hα Survey (Van Sistine et al. 2015). In the latter survey, broad-band R and narrow-band Hα filters were used to examine target galaxies from the ALFALFA blind HI survey (Giovanelli et al. 2005, Haynes et al. 2011). In the process of reducing the ALFALFA Hα Survey data the "Hα Dots" were discovered (Kellar et al. 2008, 2012). Using specialized image analysis tools, a large population of dots has already been detected in the more than 1500 ALFALFA Hα narrow-band images taken with the 0.9m WIYN and 2.1m KPNO telescopes. Follow-up spectra of over 200 Hα Dots discovered from the 0.9m images reveal that these objects are a mix of nearby low-luminosity star-forming galaxies, compact starbursts and Seyfert 2 galaxies at intermediate redshifts, and high-redshift QSOs. Here we present the first list of Hα Dots detected using 2.1m telescope data. The 2.1m images yield a sample of Dots that average almost two magnitudes fainter than those detected with the 0.9m. The current REU project is designed to characterize the set of Hα Dots detected in the deeper 2.1m telescope images, while the broad goals of the Hα Dot Survey include the desire to understand better the chemical evolution of galaxies over cosmic time. This project was supported in part by the NSF REU grant 1358980, by the Maria Mitchell Association (Nantucket, MA), and by the Massachusetts Space Grant Consortium.

  7. [The coordination of care in health centres].

    Science.gov (United States)

    Ribardière, Olivia

    2016-06-01

    Health centres are structurally designed to facilitate the coordination of care. However, evolutions in society have resulted in forms of consumption of health care which are not necessarily compatible with efficient care coordination. On a local level, teams are nevertheless organising and structuring themselves to offer the right form of care, to the right patient and at the right time. PMID:27338687

  8. Renovation of the CERN Computer Centre

    CERN Multimedia

    Patrice Loïez

    2003-01-01

    The Computer Centre at CERN is seen after half of the equipment is the large ground floor room has been removed. A large-scale spring-cleaning operation took place before renovation work for the new CERN Grid system began. Fifteen kilometres of cables that were no longer needed were removed from the cavity floor for recycling.

  9. The Australian Centre for Minesite Rehabilitation Research

    International Nuclear Information System (INIS)

    The Australian Centre for Minesite Rehabilitation Research (ACMRR) is a joint venture between the Australian mining industry through the Australian Mineral Industries Research Association Ltd. (AMIRA) and three of the organizations working most actively in this area in Australia: CSIRO Minesite Rehabilitation Research Program; University of Queensland Centre for Mined Land Rehabilitation; and Curtin University Mulga Research Centre. The ACMRR was established in July 1993 to provide a national framework to conduct Strategic Research into minesite rehabilitation. It is an industry led and funded initiative. The Goals of the Centre include: to conduct strategic research into minesite rehabilitation to provide sustainable environmental solutions which are acceptable to industry, government and the community; to be recognized as a center of excellence undertaking commissioned research on minesite rehabilitation in an independent and thorough manner; to provide scientific and technological foundations to facilitate industry and government in setting acceptable standards; to act as networking and communications focus; and to enhance education and training in minesite rehabilitation. Strategic Research Programs in: Water Systems--downstream surface and groundwater quality; Land--the long-term behavior and stability of constructed landforms; Ecosystems--the long-term sustainability of constructed landforms; Waste--the long-term treatment and disposal of waste products; will allow the ACMRR to achieve these goals through specific research projects in these areas, developed with industry sponsors. This paper will discuss their progress to date, research projects underway, and plans for the future

  10. Interorganisatorisk styring i Shared Service Centre

    DEFF Research Database (Denmark)

    Harritz, Daniel

    2011-01-01

    I den offentlige sektor er der en stigende udbredelse af Shared Service Centre (SSC). Men der er endnu meget lidt viden om de interorganisatoriske styringsproblemstillinger, der opstår når et SSC oprettes. I denne artikel præsenteres, ud fra et interorganisatorisk perspektiv, en styringsramme der...

  11. [The coordination of care in health centres].

    Science.gov (United States)

    Ribardière, Olivia

    2016-06-01

    Health centres are structurally designed to facilitate the coordination of care. However, evolutions in society have resulted in forms of consumption of health care which are not necessarily compatible with efficient care coordination. On a local level, teams are nevertheless organising and structuring themselves to offer the right form of care, to the right patient and at the right time.

  12. In the Field: The Canadian Ecology Centre.

    Science.gov (United States)

    Magee, Clare

    2000-01-01

    The Canadian Ecology Centre (Ontario) offers year-round residential and day programs in outdoor and environmental education for secondary students, field placement and internship opportunities for college students, and ecotourism programs, while providing employment and tax revenues to the local community. Dubbed consensus environmentalism, the…

  13. Centring the Subject in Order to Educate

    Science.gov (United States)

    Webster, R. Scott

    2007-01-01

    It is important for educators to recognise that the various calls to decentre the subject--or self--should not be interpreted as necessarily requiring the removal of the subject altogether. Through the individualism of the Enlightenment the self was centred. This highly individualistic notion of the sovereign self has now been decentred especially…

  14. The fragility of human-centred design

    NARCIS (Netherlands)

    Steen, M.G.D.

    2008-01-01

    In human-centred design (HCD), researchers and designers develop products in cooperation with the potential users of these products. They attempt to give users a voice or a role in their projects, with the intention of developing products that match users' needs and preferences. This approach is esp

  15. Student-Centred Learning: A Humanist Perspective

    Science.gov (United States)

    Tangney, Sue

    2014-01-01

    The notion of student-centred learning is often not defined; within the pedagogic literature it is generally associated with constructivism or principles associated with a constructivist environment such as building on prior knowledge, purposeful active learning and sense-making. An informal enquiry into conceptions of university staff prior to…

  16. The young centre of the Earth

    DEFF Research Database (Denmark)

    Uggerhøj, Ulrik Ingerslev; Mikkelsen, Rune E.; Faye, Jan

    2016-01-01

    We treat, as an illustrative example of gravitational time dilation in relativity, the observation that the centre of the Earth is younger than the surface by an appreciable amount. Richard Feynman first made this insightful point and presented an estimate of the size of the effect in a talk...

  17. Quantum-dot-in-perovskite solids

    KAUST Repository

    Ning, Zhijun

    2015-07-15

    © 2015 Macmillan Publishers Limited. All rights reserved. Heteroepitaxy - atomically aligned growth of a crystalline film atop a different crystalline substrate - is the basis of electrically driven lasers, multijunction solar cells, and blue-light-emitting diodes. Crystalline coherence is preserved even when atomic identity is modulated, a fact that is the critical enabler of quantum wells, wires, and dots. The interfacial quality achieved as a result of heteroepitaxial growth allows new combinations of materials with complementary properties, which enables the design and realization of functionalities that are not available in the single-phase constituents. Here we show that organohalide perovskites and preformed colloidal quantum dots, combined in the solution phase, produce epitaxially aligned \\'dots-in-a-matrix\\' crystals. Using transmission electron microscopy and electron diffraction, we reveal heterocrystals as large as about 60 nanometres and containing at least 20 mutually aligned dots that inherit the crystalline orientation of the perovskite matrix. The heterocrystals exhibit remarkable optoelectronic properties that are traceable to their atom-scale crystalline coherence: photoelectrons and holes generated in the larger-bandgap perovskites are transferred with 80% efficiency to become excitons in the quantum dot nanocrystals, which exploit the excellent photocarrier diffusion of perovskites to produce bright-light emission from infrared-bandgap quantum-tuned materials. By combining the electrical transport properties of the perovskite matrix with the high radiative efficiency of the quantum dots, we engineer a new platform to advance solution-processed infrared optoelectronics.

  18. Coherent transport through interacting quantum dots

    Energy Technology Data Exchange (ETDEWEB)

    Hiltscher, Bastian

    2012-10-05

    The present thesis is composed of four different works. All deal with coherent transport through interacting quantum dots, which are tunnel-coupled to external leads. There a two main motivations for the use of quantum dots. First, they are an ideal device to study the influence of strong Coulomb repulsion, and second, their discrete energy levels can easily be tuned by external gate electrodes to create different transport regimes. The expression of coherence includes a very wide range of physical correlations and, therefore, the four works are basically independent of each other. Before motivating and introducing the different works in more detail, we remark that in all works a diagrammatic real-time perturbation theory is used. The fermionic degrees of freedom of the leads are traced out and the elements of the resulting reduced density matrix can be treated explicitly by means of a generalized master equation. How this equation is solved, depends on the details of the problem under consideration. In the first of the four works adiabatic pumping through an Aharonov-Bohm interferometer with a quantum dot embedded in each of the two arms is studied. In adiabatic pumping transport is generated by varying two system parameters periodically in time. We consider the two dot levels to be these two pumping parameters. Since they are located in different arms of the interferometer, pumping is a quantum mechanical effect purely relying on coherent superpositions of the dot states. It is very challenging to identify a quantum pumping mechanism in experiments, because a capacitive coupling of the gate electrodes to the leads may yield an undesired AC bias voltage, which is rectified by a time dependent conductance. Therefore, distinguishing features of these two transport mechanisms are required. We find that the dependence on the magnetic field is the key feature. While the pumped charge is an odd function of the magnetic flux, the rectified current is even, at least in

  19. Treatment Outcomes of Patients Placed on Treatment Under Directly Observed Therapy Short-Course (Dots)

    Science.gov (United States)

    Kaur, Gurpreet; Goel, N.K.; Kumar, Dinesh; Janmeja, A.K.; Swami, H.M.; Kalia, Meenu

    2008-01-01

    Background: Tuberculosis continues to be a pressing health problem in India. The Revised National Tuberculosis Programme (RNTCP), an application of Directly Observed Treatment Short-course (DOTS) in India, launched in 1997 needs continuous evaluation. Objective: To study the outcomes of treatment among the patients put on DOTS under RNTCP in Chandigarh, UT. Material & Methods: A Longitudinal study was conducted during 2004-2005 in 13 Microscopic centres (MC's) spread over 2 Tuberculosis Units (TU's) under District Tuberculosis Centre (DTC) in Union Territory (UT), Chandigarh. A sample of 265 respondents, selected by two-stage stratified random sampling technique, was recruited in the study cohort. Data analysis was done using SPSS-10 statistical software package. Results: For Category I and Category II patients, the Success rate was 98.6% and 90.4% respectively. The overall default rate was 1.1% and failure rate was 2.6%. For re-treatment cases, failure rate was higher i.e. 5.8%. The sputum conversion rate among the new smear positive cases was 93.8% at 3 months of treatment. For the re-treatment cases, spu-tum conversion rate at 3 months was 94.1%. Conclusion: The study concludes that RNTCP is running successfully in UT Chandigarh, having high success rate and low default rate. The reasons for high failure rate should be explored in depth. PMID:20165654

  20. Treatment outcomes of patients placed on treatment under directly observed therapy short-course (DOTS

    Directory of Open Access Journals (Sweden)

    Kaur Gurpreet

    2008-01-01

    Full Text Available Background : Tuberculosis continues to be a pressing health problem in India. The Revised National Tuberculosis Programme (RNTCP, an application of Directly Observed Treatment Short-course (DOTS in India, launched in 1997 needs contin-uous evaluation. Objective : To study the outcomes of treatment among the patients put on DOTS under RNTCP in Chandigarh, UT. Material & Methods : A Longitudi-nal study was conducted during 2004-2005 in 13 Microscopic centres (MC′s spread over 2 Tuberculosis Units (TU′s under District Tuberculosis Centre (DTC in Union Territory (UT, Chandigarh. A sample of 265 respondents, selected by two-stage stratified random sampling technique, was recruited in the study cohort. Data analysis was done using SPSS-10 statistical software package. Results : For Category I and Category II patients, the Success rate was 98.6% and 90.4% respectively. The overall default rate was 1.1% and failure rate was 2.6%. For re-treatment cases, failure rate was higher i.e. 5.8%. The sputum conversion rate among the new smear positive cases was 93.8% at 3 months of treatment. For the re-treatment cases, spu-tum conversion rate at 3 months was 94.1%. Conclusion : The study concludes that RNTCP is running successfully in UT Chandigarh, having high success rate and low default rate. The reasons for high failure rate should be explored in depth.

  1. Dot-dye-immunoassay for the diagnosis of schistosomiasis mansoni

    Directory of Open Access Journals (Sweden)

    Ana Lúcia Teles Rabello

    1992-06-01

    Full Text Available A new serological assay dot-dye-immunoassay (dot-DIA was evaluated for the diagnosis of schistosomiasis mansoni. This method consist of four steps: (a biding of antigens to a nitrocellulose membrane (NC; (b blocking of free sites of the NC; (c incubation in specific primary antibody; (d detection of primary antibody reactivity by color development using second antibody coupled to textile dyes. Sera from 82 individuals, 61 with Schistosoma mansoni eggs in the stool and 21 stool negative were tested by ELISA, dot-ELISA, and dotDIA. A high level of agreement between the methods tested was observed for all sera tested: ELISA x dot-ELISA: 95.1%, ELISA x dot-DIA: 92.7% and dot-ELISA x dot-DIA: 97.6%. In this study, dot-DIA proved to be a feasible, sensitive, rapid and practical test for the diagnosis of shcistosomiasis.

  2. Person-centred care in nursing documentation.

    LENUS (Irish Health Repository)

    Broderick, Margaret C

    2012-12-07

    BACKGROUND: Documentation is an essential part of nursing. It provides evidence that care has been carried out and contains important information to enhance the quality and continuity of care. Person-centred care (PCC) is an approach to care that is underpinned by mutual respect and the development of a therapeutic relationship between the patient and nurse. It is a core principle in standards for residential care settings for older people and is beneficial for both patients and staff (International Practice Development in Nursing and Healthcare, Chichester, Blackwell, 2008 and The Implementation of a Model of Person-Centred Practice in Older Person Settings, Dublin, Health Service Executive, 2010a). However, the literature suggests a lack of person-centredness within nursing documentation (International Journal of Older People Nursing 2, 2007, 263 and The Implementation of a Model of Person-Centred Practice in Older Person Settings, Dublin, Health Service Executive, 2010a). AIMS AND OBJECTIVES: To explore nursing documentation in long-term care, to determine whether it reflected a person-centred approach to care and to describe aspects of PCC as they appeared in nursing records. METHOD: A qualitative descriptive study using the PCN framework (Person-centred Nursing; Theory and Practice, Oxford, Wiley-Blackwell, 2010) as the context through which nursing assessments and care plans were explored. RESULTS: Findings indicated that many nursing records were incomplete, and information regarding psychosocial aspects of care was infrequent. There was evidence that nurses engaged with residents and worked with their beliefs and values. However, nursing documentation was not completed in consultation with the patient, and there was little to suggest that patients were involved in decisions relating to their care. IMPLICATIONS FOR PRACTICE: The structure of nursing documentation can be a major obstacle to the recording of PCC and appropriate care planning. Documentation

  3. Nuclear Electric Visitor Centres - Innovation and inspiration

    International Nuclear Information System (INIS)

    Full text: This eight minute video demonstrates the approach taken by Nuclear Electric to exhibitions that are open to the public. The information is given both visually - with excerpts from some of the attractions on display at the centres - and in comments from interviews with visitors, the centre guides and the man responsible for many of the exhibits featured in the video. on one side are the schoolchildren who are visiting the exhibition and are seen both playing and learning as they press buttons, watch videos, 'meet' Michael Faraday, and learn about radiation - its disposal and its safe transportation. The headmaster of the school is interviewed and explains that the exhibition is helping his children understand the importance of electricity to their world. on the other side is Jackie Lucas, the visitor centre manager, explaining what the public make of the exhibition. We see her staff greeting the children and helping them to understand the show. The designer of the exhibition, Len Upton explains how you go about making an exhibition such as this both informative and fun. Also interviewed is the man behind many of the exhibitions featured at Nuclear Electric's visitor centres up and down the country, Nicholas Mullane. He explains the purpose of the exhibition and what messages it imparts. The video is presented in split-screen or composite format, whereby the interviewee and children are often presented together. Excerpts from the various videos on display are presented as both how they are seen from the floor, as well as the full screen effect of the various programmes. The video gives much of the feeling of fun to be gained at the exhibition, as well as showing the educational benefits to be gained from a couple of hours at one of Nuclear Electric's visitor centres. Copies of the video can be obtained from Bob Fenton at Nuclear Electric. (Fax: ++44 1 452 652 443). (author)

  4. A new structure to increase the photostability of CdTe quantum dot sensitized solar cells

    International Nuclear Information System (INIS)

    In this paper a new cell structure is introduced to reduce the rate of CdTe corrosion in quantum dot sensitized solar cells (QDSSCs) using I-/I3- electrolyte. In this cell, one electrode is a titania nanorod that was sensitized with CdTe quantum dots as the working electrode. A thin gold layer is sputtered on the electrode to act as a protective layer against the I-/I3- corrosive electrolyte and to passivate the CdTe surface traps which are the main recombination centres in a QDSSC. In addition, a Schottky barrier formed at the interface of Au and CdTe prevents direct electron recombination from the CdTe conduction band with I3- ions. The mechanism of charge transfer and quantum dot regeneration in the presence of gold layer is discussed and our results show that the solar cells made of TiO2/CdTe/Au photoanode have more photostability and a higher fill factor relative to the TiO2/CdTe photoanodes.

  5. Realistic model of a vertical pillar quantum dot: Analysis of individual dot data

    NARCIS (Netherlands)

    Maksym, P.A.; Nishi, Y.; Austing, D.G.; Hatano, T.; Kouwenhoven, L.P.; Aoki, H.; Tarucha, S.

    2009-01-01

    An accurate model of a vertical pillar quantum dot is described. The full three-dimensional structure of the device containing the dot is taken into account and this leads to an effective two-dimensional model in which electrons move in the two lateral dimensions, the confinement is parabolic, and t

  6. Submonolayer Quantum Dot Infrared Photodetector

    Science.gov (United States)

    Ting, David Z.; Bandara, Sumith V.; Gunapala, Sarath D.; Chang, Yia-Chang

    2010-01-01

    A method has been developed for inserting submonolayer (SML) quantum dots (QDs) or SML QD stacks, instead of conventional Stranski-Krastanov (S-K) QDs, into the active region of intersubband photodetectors. A typical configuration would be InAs SML QDs embedded in thin layers of GaAs, surrounded by AlGaAs barriers. Here, the GaAs and the AlGaAs have nearly the same lattice constant, while InAs has a larger lattice constant. In QD infrared photodetector, the important quantization directions are in the plane perpendicular to the normal incidence radiation. In-plane quantization is what enables the absorption of normal incidence radiation. The height of the S-K QD controls the positions of the quantized energy levels, but is not critically important to the desired normal incidence absorption properties. The SML QD or SML QD stack configurations give more control of the structure grown, retains normal incidence absorption properties, and decreases the strain build-up to allow thicker active layers for higher quantum efficiency.

  7. Measurement of Eccentricity of the Centre of Mass from the Geometric Centre of a Sphere

    Institute of Scientific and Technical Information of China (English)

    郭俊起; 胡忠坤; 顾邦明; 罗俊

    2004-01-01

    The eccentricity of the centre of mass from the geometric centre of a spherical attracting mass in determining the Newtonian gravitational constant G is tested by means of an electronic balance. The experimental result shows that the eccentricity of the sample is about 0.31 μm with uncertainty of 0.05 μm. Two density distribution models are discussed to estimate the uncertainty to G by the eccentricities of the attracting masses.

  8. Understanding electronic systems in semiconductor quantum dots

    Science.gov (United States)

    Ciftja, Orion

    2013-11-01

    Systems of confined electrons are found everywhere in nature in the form of atoms where the orbiting electrons are confined by the Coulomb attraction of the nucleus. Advancement of nanotechnology has, however, provided us with an alternative way to confine electrons by using artificial confining potentials. A typical structure of this nature is the quantum dot, a nanoscale system which consists of few confined electrons. There are many types of quantum dots ranging from self-assembled to miniaturized semiconductor quantum dots. In this work we are interested in electrostatically confined semiconductor quantum dot systems where the electrostatic confining potential that traps the electrons is generated by external electrodes, doping, strain or other factors. A large number of semiconductor quantum dots of this type are fabricated by applying lithographically patterned gate electrodes or by etching on two-dimensional electron gases in semiconductor heterostructures. Because of this, the whole structure can be treated as a confined two-dimensional electron system. Quantum confinement profoundly affects the way in which electrons interact with each other, and external parameters such as a magnetic field. Since a magnetic field affects both the orbital and the spin motion of the electrons, the interplay between quantum confinement, electron-electron correlation effects and the magnetic field gives rise to very interesting physical phenomena. Thus, confined systems of electrons in a semiconductor quantum dot represent a unique opportunity to study fundamental quantum theories in a controllable atomic-like setup. In this work, we describe some common theoretical models which are used to study confined systems of electrons in a two-dimensional semiconductor quantum dot. The main emphasis of the work is to draw attention to important physical phenomena that arise in confined two-dimensional electron systems under various quantum regimes.

  9. Effects of unstratified and centre-stratified randomization in multi-centre clinical trials.

    Science.gov (United States)

    Anisimov, Vladimir V

    2011-01-01

    This paper deals with the analysis of randomization effects in multi-centre clinical trials. The two randomization schemes most often used in clinical trials are considered: unstratified and centre-stratified block-permuted randomization. The prediction of the number of patients randomized to different treatment arms in different regions during the recruitment period accounting for the stochastic nature of the recruitment and effects of multiple centres is investigated. A new analytic approach using a Poisson-gamma patient recruitment model (patients arrive at different centres according to Poisson processes with rates sampled from a gamma distributed population) and its further extensions is proposed. Closed-form expressions for corresponding distributions of the predicted number of the patients randomized in different regions are derived. In the case of two treatments, the properties of the total imbalance in the number of patients on treatment arms caused by using centre-stratified randomization are investigated and for a large number of centres a normal approximation of imbalance is proved. The impact of imbalance on the power of the study is considered. It is shown that the loss of statistical power is practically negligible and can be compensated by a minor increase in sample size. The influence of patient dropout is also investigated. The impact of randomization on predicted drug supply overage is discussed.

  10. It's all change at the Computer Centre

    CERN Multimedia

    Laëtitia Pedroso

    2011-01-01

    The IT and EN Departments are modernising the infrastructure of the Computer Centre to improve the conditions in which the equipment has to operate and to increase capacity. The construction work has already begun and is due to be completed in October 2012.   Every year CERN experiences around ten power cuts lasting from less than a second to several hours. In most cases the two protection systems - the UPS* and the diesel generators – are able to ensure that the operation of the Computer Centre is not affected. As Vincent Doré, the project leader for the IT Department, and Paul Pepinster, the EN Department's technical coordinator in charge of modernising the infrastructure, explains: "Building 513 has two types of computing facilities – the "non-critical" ones, such as the servers for "off-line" computing, which have UPS systems ensuring that they can operate for 10 minutes after a power cut, and the "critical&...

  11. JOB CENTRE FOR DOMESTIC STAFF IN SWITZERLAND

    CERN Multimedia

    Relations with the Host States Service; http://www.cern.ch/relations/

    2001-01-01

    The Permanent mission of Switzerland to the International Organisations in Geneva has informed CERN that the Geneva Welcome Centre has set up an employment registration desk for the domestic staff of international civil servants. The aim of this pilot project is, on the one hand, to help international civil servants find domestic staff and, on the other hand, to help domestic staff holding an 'F'-type carte de légitimation find employment within 30 days after the expiry of a contract. For more information, please contact the Geneva Welcome Centre, La Pastorale, 106, route de Ferney, Case postale 103, 1211 Genève 20, tel. (+41.22) 918 02 70, fax (+41.22) 918 02 79), http://geneva-international.org/Welcome.E.html.

  12. Frequency selectivity at very low centre frequencies

    DEFF Research Database (Denmark)

    Orellana, Carlos Andrés Jurado; Pedersen, Christian Sejer; Marquardt, Torsten

    2010-01-01

    A significant factor in the decrease of sensitivity to low-frequency sound is the helicotrema shunt effect. In humans, it causes a slope increase of the middle-ear transfer function (METF) from 6 dB/oct to 12 dB/oct below approximately 50 Hz [Marquardt et al., J.Acoust. Soc. Am. 121, 3628...... measurements based on OAE suppression techniques and notched-noise masking data psychophysically measured for centre frequencies in the range 50-125 Hz, this study examines how individual differences in frequency selectivity, as well as in masking, may occur at very low CFs due to individual differences......-3638 (2007)]. Recent experiments showed that the exact frequency varies from individual to individual. Besides, the helicotrema region in the METF has been found to highly influence frequency selectivity for centre frequencies (CFs) below 80 Hz (Jurado and Moore in prep). By using individual METF...

  13. Patient-centred Prevention among PAD Patients

    DEFF Research Database (Denmark)

    Pii, Kathrine Hoffmann

    2014-01-01

    that will improve their health condition. The patient-centred approach (and related concepts: patient participation, involvement, and empowerment) is being promoted both in healthcare politics and by healthcare professionals as a way to achieve more active self-managing and self-caring patients. Patient......-centredness is thus promoted as a way to organize health more effectively (in terms of cost and treatment outcomes) and as a way to ensure patients’ autonomy and fundamental right to make their own decisions regarding their treatment. Critical voices within social and nursing theory have however argued...... that the patient-centred approach does not ensure patient autonomy, but continues to be organized according to biomedical regimes and thereby carry on a paternalistic approach. In this paper, I present findings from a PhD project, which investigates how the ideal of patient-centredness is practiced in the case...

  14. Danish Polymer Centre annual report 2001

    DEFF Research Database (Denmark)

    Hassager, O.; Hvilsted, S.; Mortensen, Kell

    The centre is a collaboration between the Risø National Laboratory and the Technical University of Denmark (DTU). At the DTU the Department of Chemical Engineering and the Department of Manufacturing Engineering and Management participate in the centre.From 2001 the Polymer Department at Risø...... coordinates the activities at Risø From the outset it was considered important with common laboratories to obtain the full effect of the collaboration between the two departments at the DTU and Risø NationalLaboratory. In 2001 new laboratories for polymer research and education were established at the DTU...... campus in Lyngby as shown in the pictures on this page. In addition to well equipped laboratories at Risø which will be expanded in 2002 and 2003, thesefacilities provide a common ground for polymer chemists, polymer physicists, chemical engineers and mechanical engineers from the two institutions...

  15. Display-centred applications in ubiquitous computing

    OpenAIRE

    José, Rui; Pinto, Helder

    2006-01-01

    Public displays can play an important enabling role in ubiquitous computing environments. This paper describes an on-going work for a multipurpose, multi-display infrastructure, designed to address the requirements of display-centred applications in ubiquitous computing environments. The system provides an infrastructure in which situated displays can act as portals to the physical space, allowing ubicomp applications to support their association with the physical world by providing them with...

  16. The Researcher : The Refugee Documentation Centre Newsletter

    OpenAIRE

    Ahmed, Elisabeth; Goggins, David

    2014-01-01

    Contents: Subsidiary Protection – a distinct and autonomous form of complementary protection / Enda O’Neill, Jennifer Higgins, UNHCR Ireland; Recent Changes at the Refugee Appeals Tribunal / Barry Magee, Refugee Appeals Tribunal; The Use of Decision Templates for Refugee Status Determination / Seán O’Connell, Refugee Appeals Tribunal; Forced Marriage in Afghanistan / David Goggins, Refugee Documentation Centre; Houses of the Holy: Iraq and the last days of the Mandeans / Patrick Dowling, R...

  17. Structure and Responsibilities of Radiation Protection Centre

    International Nuclear Information System (INIS)

    Constitution of Radiation Protection Centre (RPC) in Lithuania is presented. RPC was established in 1997, in 1999 the Government granted the status of the regulatory authority of Lithuania on radiation protection issues. Currently there are two departments at RPC: two in Vilnius - Department of Radiation Protection Supervision and Control and Department of Programs and Expertise, and four in the districts. Main tasks of RPC are listed

  18. Imperial College Reactor Centre annual report. 1983

    International Nuclear Information System (INIS)

    It is reported that the reactor operated reliably during the year with less than half a day of operating time lost by faults or failures. Brief accounts of the 34 research projects at the Centre are given, and a list of teaching experiments or visits is included. These include undergraduate and post-graduate teaching. Commercial requests for irradiations and neutron activation analysis are reported as increasing. (U.K.)

  19. CMS Centres Worldwide - a New Collaborative Infrastructure

    CERN Document Server

    Taylor, Lucas

    2011-01-01

    Webcasts, and generic Web tools such as CMS-TV for broadcasting live monitoring and outreach information. Being Web-based and experiment-independent, these systems could easily be extended to other organizations. We describe the experiences of using CMS Centres Worldwide in the CMS data-taking operations as well as for major media events with several hundred TV channels, radio stations, and many more press journalists simultaneously around the world.

  20. Learning Styles of Independent Learning Centre Users

    OpenAIRE

    Tarik Uzun

    2014-01-01

    Learning style research has been a significant field within language teaching and learning. There have been very few attempts, however, to seek possible links between independent learning and learning style preferences. This paper aims to identify the learning styles of students who use the Independent Learning Centre (ILC) on a regular basis at a state university in Turkey (n=102). The findings of the learning style analysis revealed that, contrary to expectations, most of the regular users ...

  1. LSE centre for economic performance: bankers’ bonuses

    OpenAIRE

    Bell, Brian

    2010-01-01

    A new series of Election Analyses is now available from the LSE’s Centre for Economic Performance (CEP). The series will discuss the research evidence on some of the key policy battlegrounds of the 2010 General Election, including macroeconomic policy, immigration, health, education, crime, poverty and inequality, labour market policy, regional policy, energy and the environment, financial regulation and bankers’ bonuses, and foreign aid. The latest CEP Election Analysis, by Brian Bell, g...

  2. Enhancing Safety at Airline Operations Control Centre

    Directory of Open Access Journals (Sweden)

    Lukáš Řasa

    2015-04-01

    Full Text Available In recent years a new term of Safety Management System (SMS has been introduced into aviation legislation. This system is being adopted by airline operators. One of the groundbased actors of everyday operations is Operations Control Centre (OCC. The goal of this article has been to identify and assess risks and dangers which occur at OCC and create a template for OCC implementation into SMS.

  3. The LifeWatch Service Centre Plan

    OpenAIRE

    Parr, Terry; Spinelli, Oliviero; Mauri, Maria Paola; Billisari, Livia; Hardisty, Alex; Ludlow, David; Khan, Zaheer; Roberts, Dave; Sleep, Chris; Sier, Andrew

    2011-01-01

    This report summarises the construction plan for the Lifewatch Service Centre. The main purpose of LifeWatch is to serve the biodiversity and ecosystem research community in its work on the understanding and rational management of our ecosystems for use by policy makers, resource managers, the private sector and the general public. To do this the LifeWatch infrastructure will provide capabilities to analyse, model and simulate with integrated biodiversity and ecosystem data from many dive...

  4. User-Centred Design Using Gamestorming.

    Science.gov (United States)

    Currie, Leanne

    2016-01-01

    User-centered design (UX) is becoming a standard in software engineering and has tremendous potential in healthcare. The purpose of this tutorial will be to demonstrate and provide participants with practice in user-centred design methods that involve 'Gamestorming', a form of brainstorming where 'the rules of life are temporarily suspended'. Participants will learn and apply gamestorming methods including persona development via empathy mapping and methods to translate artefacts derived from participatory design sessions into functional and design requirements.

  5. Training science centre Explainers. The Techniquest experience

    Directory of Open Access Journals (Sweden)

    Colin Johnson

    2005-12-01

    Full Text Available Techniquest was established in 1986, and in 1995 moved to its current premises at Cardiff Bay, South Wales. This was the first purpose-built science centre in the UK. It receives around 200,000 visitors every year to its exhibition, and to its programmes for schools and public audiences in the theatre, laboratory, discovery room and planetarium. The author joined the Techniquest project in 1985, became a staff member in 1990 and was the Chief Executive from 1997 until his retirement in 2004. Techniquest has three “out-stations” in Wales, and is responsible for the supply and maintenance of exhibits to the Look Out Discovery Centre in Bracknell, England. There is a Techniquest gallery at the Lisbon Pavilhão do Conhecimento - Ciência Viva, and a traveling exhibition, SciQuest, in South Africa which was also supplied by Techniquest. All these centres rely on the effective intervention of “Explainers” (at Techniquest we call them “Helpers” to provide the best possible experience for visitors. At its most demanding, the tasks of an Explainer are varied and intensive, yet there may be times when the duties are mundane or even dull. When you rely on people to act as both hosts and housekeepers, to provide both support and stimulus, and to be both welcoming and watchful, you are asking a great deal. This article raises some of the issues concerned with the recruitment and retention of Explainers, their training and management, and the way in which their role is recognized and valued by the science centre as a whole.

  6. INFOTERM – Information Disseminating Centre for Terminology

    Directory of Open Access Journals (Sweden)

    Albina Auksoriūtė

    2014-12-01

    Full Text Available International Information Centre for Terminology (INFOTERM was founded in 1971 by contract with the United Nations Educational, Scientific and Cultural Organization (UNESCO and the Austrian Standards Institute (ASI. In 1996, INFOTERM was reorganized and established as an independent non-profit organization. INFOTERM promotes and supports the cooperation of existing and the establishment of new terminology centres and networks with the general aim to improve domain communication, knowledge transfer and provision of content with view to facilitating the participation of all in the global multilingual knowledge society. The article presents not only a history of the foundation of INFOTERM, the tasks and activities of INFOTERM and its members, which are international, regional or national terminology institutions, organizations and networks, as well as specialized public or semi-public or other non-profit institutions engaged in terminological activities, but also analyses “Guidelines for terminology policies”, preparied by INFOTERM, and cooperation between INFOTERM and the Institute of the Lithuanian Language.In conclusion, the experience and sharing expertise of INFOTERM regarding harmonized methods and guidelines for terminology management and policies, the management of terminology centres, terminology standardization, the use of terminological data, methods and tools in all applications etc are very important for all countries and language communities especially for countries and language communities with less mature terminologies. The Institute of the Lithuanian Language as a member of INFOTERM has a possibility to get information on terminology research and training, terminology publications, terminological events and activities all over the world.

  7. Upcoming opening of CERN's new Mobility Centre

    CERN Multimedia

    2016-01-01

    On 29 February, CERN’s brand new Mobility Centre opened in the Globe car park. The Centre has been created to cater to the transport needs of everyone at CERN, to simplify procedures and to centralise all the transport services on offer: the rental of CERN bikes and cars, the CERN car-sharing scheme and SIXT car rental.   From 29 February onwards, the Mobility Centre in the Globe car park will be the place to go for all your duty travel needs: rental of CERN cars (with or without the CERN logo), SIXT car rental, CERN bike rental, distribution of cards allowing the use of CERN’s self-service bike- and car-sharing schemes. That same day, the premises currently housing the Car Pool in Building 130 will become the CERN garage, responsible for: upkeep and repairs on CERN bikes, minor maintenance work on CERN vehicles (e.g. replacing windscreen wipers, bulbs and fuses, refilling windscreen washer fluid, pumping up tyres, etc.), arranging and following up the repair and maintenan...

  8. A new visitor centre for CMS

    CERN Multimedia

    2001-01-01

    At the inauguration of the new CMS visitor centre. The CMS experiment inaugurated a new visitor centre at its Cessy site on 14 June. This will allow the thousands of people who come to CERN each year to follow the construction of one the Laboratory's flagship experiments first-hand. CERN receives over 20,000 visitors each year. Until recently, many of them were taken on a guided tour of one of the LEP experiments. With the closure of LEP, however, trips underground are no longer possible, and the Visits' Service has put in place a number of other itineraries (Bulletin 46/2000). Since the CMS detector will be almost entirely constructed in a surface hall, it is now taking a big share of the limelight. The CMS visitor centre has been built on a platform overlooking CMS construction. It contains a set of clear descriptive posters describing the experiment, along with a video projection showing animations and movies about CMS construction. In the coming weeks, a display of CMS detector elements will be added, as...

  9. Gamma Rays frim the Galactic Centre

    CERN Document Server

    Erlykin, A D

    2007-01-01

    Recent results from the HESS gamma ray telescope have shown the presence of both a diffuse, extended, flux of gamma rays above ~0.4 TeV and discrete sources in and near the Galactic Centre. Here, we put forward a possible explanation in terms of the diffusion of cosmic ray protons from a succession of supernova remnants (SNR) in the SgrA* region of the Galaxy plus a contribution from SNR in the rest of the Galactic Centre Region, to be called the Galactic Centre Ridge (GCR). Protons are favoured over electrons because the mG magnetic fields in the Region will attenuate energetic electrons severely. Prominent features are the need for 'anomalous diffusion' of the protons in the whole region and the adoption of low efficiency for SNR acceleration in the high density regions. The latter is related by us to the well-known low 'cosmic ray gradient' in the Galaxy. A corroborating feature is the close correlation of inferred cosmic ray intensity with the smoothed intensity of 5 GHZ radio radiation. We attribute this...

  10. Colloidal Quantum dot photovoltaics: Tuning optoelectronic properties

    International Nuclear Information System (INIS)

    Full text: Colloidal quantum dots combine processing from the solution phase with tunability of the bandgap. Via the size-effect the optical properties can be matched to the solar spectrum for a wide-range photon harvesting. To engineer photovoltaic devices, quantum dots are compressed from their colloidal form into a close-packed nanocrystal matrix, while undergoing a systematic layer-by-layer process. The resulting quantum dot solid is treated as semiconductor medium - one having electron-hole mobilites, free carrier densities and a dielectric constant. While the size-effect determined the band-gap before, it is now the nature of ligand and the treatment route, that influences mentioned electronic parameters. We took the view on the processing steps and found a concept for analysing trap states, moblility and device performance in real quantum dot solids. Our findings emphasize the interplay of mobility and trap-distribution with routes that take special care on the nanocrystal surface and hence conserve optoelectronic qualities of quantum dots for efficient photovoltaic cells. (author)

  11. Photoluminescence of carbon dots from mesoporous silica

    Science.gov (United States)

    Nelson, D. K.; Razbirin, B. S.; Starukhin, A. N.; Eurov, D. A.; Kurdyukov, D. A.; Stovpiaga, E. Yu; Golubev, V. G.

    2016-09-01

    Photophysical properties of carbon dots were investigated under various excitation conditions and over a wide temperature region - from room to liquid helium temperatures. The carbon dots (CDs) were synthesized using mesoporous silica particles as a reactor and (3-aminopropyl)triethoxysilane (APTES) as a precursor. The photoluminescence spectra of CDs exhibit a strong dependence on the excitation wavelength and demonstrate a significant inhomogeneous broadening. Lowering sample temperature reveals the doublet structure of the spectra, which is associated with the vibronic structure of radiative transitions. The vibration energy ∼1200 cm-1 is close to the energy of Csbnd O stretching vibration. Long-lived phosphorescence of carbon dots with its decay time ∼0.2 s at T = 80 K was observed. The fluorescence and phosphorescence spectra are shown to be spectrally separated. The long-lived component of the emission was ascribed to optically forbidden triplet-singlet transitions. The value of the singlet-triplet splitting was found to be about 0.3 eV. Photo-induced polarization of the luminescence of carbon dots was revealed. The degree of the linear polarization is dependent on the wavelengths of both excitation and emitted light. The effect indicates a hidden anisotropy of optical dipole transitions in the dots and demonstrates the loss of the dipole orientation during the electron energy relaxation.

  12. Inorganic passivation and doping control in colloidal quantum dot photovoltaics

    KAUST Repository

    Hoogland, Sjoerd H.

    2012-01-01

    We discuss strategies to reduce midgap trap state densities in colloidal quantum dot films and requirements to control doping type and magnitude. We demonstrate that these improvements result in colloidal quantum dot solar cells with certified 7.0% efficiency.

  13. Nanosized Carbon Dots from Organic Matter and Biomass

    Institute of Scientific and Technical Information of China (English)

    LI Yuanyuan; CHEN Tong; MA Yulong

    2016-01-01

    Carbon nanoparticles (C-dots) were prepared by relfuxing the combustion soots of candles and corn stalk in nitric acid. The synthesized C-dots were characterized. The results showed a sharp increase in oxygen content and a sharp decrease in carbon content after oxidation. The C-dots had -OH and -CO2H groups introduced which made them hydrophilic. However, their difference was also obvious. The C-dots from candle soot had a 10-45 nm broad particle size distribution, and those from corn stalk soot had a 6-18 nm relatively small and narrow size distribution. The C-dots were mainly ofsp2 andsp3 carbon structure different from the C-dots of diamond-like structure from candle soot. Interestingly, two kinds of C-dots all exhibited unique photoluminescent properties. The obtained C-dots have potential applications in a broad range of areas.

  14. Origins and optimization of entanglement in plasmonically coupled quantum dots

    Science.gov (United States)

    Otten, Matthew; Larson, Jeffrey; Min, Misun; Wild, Stefan M.; Pelton, Matthew; Gray, Stephen K.

    2016-08-01

    A system of two or more quantum dots interacting with a dissipative plasmonic nanostructure is investigated in detail by using a cavity quantum electrodynamics approach with a model Hamiltonian. We focus on determining and understanding system configurations that generate multiple bipartite quantum entanglements between the occupation states of the quantum dots. These configurations include allowing for the quantum dots to be asymmetrically coupled to the plasmonic system. Analytical solution of a simplified limit for an arbitrary number of quantum dots and numerical simulations and optimization for the two- and three-dot cases are used to develop guidelines for maximizing the bipartite entanglements. For any number of quantum dots, we show that through simple starting states and parameter guidelines, one quantum dot can be made to share a strong amount of bipartite entanglement with all other quantum dots in the system, while entangling all other pairs to a lesser degree.

  15. Filtering algorithm for dotted interferences

    Energy Technology Data Exchange (ETDEWEB)

    Osterloh, K., E-mail: kurt.osterloh@bam.de [Federal Institute for Materials Research and Testing (BAM), Division VIII.3, Radiological Methods, Unter den Eichen 87, 12205 Berlin (Germany); Buecherl, T.; Lierse von Gostomski, Ch. [Technische Universitaet Muenchen, Lehrstuhl fuer Radiochemie, Walther-Meissner-Str. 3, 85748 Garching (Germany); Zscherpel, U.; Ewert, U. [Federal Institute for Materials Research and Testing (BAM), Division VIII.3, Radiological Methods, Unter den Eichen 87, 12205 Berlin (Germany); Bock, S. [Technische Universitaet Muenchen, Lehrstuhl fuer Radiochemie, Walther-Meissner-Str. 3, 85748 Garching (Germany)

    2011-09-21

    An algorithm has been developed to remove reliably dotted interferences impairing the perceptibility of objects within a radiographic image. This particularly is a major challenge encountered with neutron radiographs collected at the NECTAR facility, Forschungs-Neutronenquelle Heinz Maier-Leibnitz (FRM II): the resulting images are dominated by features resembling a snow flurry. These artefacts are caused by scattered neutrons, gamma radiation, cosmic radiation, etc. all hitting the detector CCD directly in spite of a sophisticated shielding. This makes such images rather useless for further direct evaluations. One approach to resolve this problem of these random effects would be to collect a vast number of single images, to combine them appropriately and to process them with common image filtering procedures. However, it has been shown that, e.g. median filtering, depending on the kernel size in the plane and/or the number of single shots to be combined, is either insufficient or tends to blur sharp lined structures. This inevitably makes a visually controlled processing image by image unavoidable. Particularly in tomographic studies, it would be by far too tedious to treat each single projection by this way. Alternatively, it would be not only more comfortable but also in many cases the only reasonable approach to filter a stack of images in a batch procedure to get rid of the disturbing interferences. The algorithm presented here meets all these requirements. It reliably frees the images from the snowy pattern described above without the loss of fine structures and without a general blurring of the image. It consists of an iterative, within a batch procedure parameter free filtering algorithm aiming to eliminate the often complex interfering artefacts while leaving the original information untouched as far as possible.

  16. Addressing the challenges of patient-centred design

    Directory of Open Access Journals (Sweden)

    Karen LaBat

    2009-11-01

    Full Text Available Patient-centred design is a relatively new term, but a longstanding concept in clinical practice. This discussion looks at patient-centred design and explores the relationships of patient-centred design to universal design, user-centred design and the newer human-centred design. It also explores why interdisciplinary approaches are needed for patient-centred design and how interdisciplinary collaboration works to address the challenges of patient centred design. Successful patient-centred solutions can grow from collaborations which include shared visions, understanding of both the nature and degree of variation in the patient,materials, and the designed solution, clear regular communication among all parties with careful definition of terms, and respect for the inherent cultures of all disciplines involved.

  17. Coherence and dephasing in self-assembled quantum dots

    DEFF Research Database (Denmark)

    Hvam, Jørn Märcher; Leosson, K.; Birkedal, Dan

    2003-01-01

    We measured dephasing times in InGaAl/As self-assembled quantum dots at low temperature using degenerate four-wave mixing. At 0K, the coherence time of the quantum dots is lifetime limited, whereas at finite temperatures pure dephasing by exciton-phonon interactions governs the quantum dot...... coherence. The inferred homogeneous line widths are significantly smaller than the line widths usually observed in the photoluminescence from single quantum dots indicating an additional inhomogeneours broadening mechanism in the latter....

  18. Short-wave infrared colloidal quantum dot photodetectors on silicon

    OpenAIRE

    Hu, Chen; Gassenq, Alban; Justo, Yolanda; Yakunin, Sergii; Heiss, Wolfgang; Hens, Zeger; Roelkens, Gunther

    2013-01-01

    In this paper, two kinds of colloidal quantum dots, PbS and HgTe, are explored for SWIR photodetectors application. The colloidal dots are prepared by hot injection chemical synthesis, with organic ligands around the dots keeping them stable in solution. For the purpose of achieving efficient carrier transport between the dots in a film, these long organic ligands are replaced by shorter, inorganic ligands. We report uniform, ultra-smooth colloidal QD films without cracks realized by dip-coat...

  19. Quantum Dots in Photonic Crystal Waveguides

    DEFF Research Database (Denmark)

    Sollner, Immo Nathanael

    This Thesis is focused on the study of quantum electrodynamics in photonic crystal waveguides. We investigate the interplay between a single quantum dot and the fundamental mode of the photonic crystal waveguide. We demonstrate experimental coupling eciencies for the spontaneous emission...... into the mode exceeding 98% for emitters spectrally close to the band-edge of the waveguide mode. In addition we illustrate the broadband nature of the underlying eects, by obtaining coupling eciencies above 90% for quantum dots detuned from the band edge by as far as 20nm. These values are in good agreement...... quantum-dot-waveguide coupling. Such a structure is ideally suited for a number of applications in quantum information processing and among others we propose an on-chip spin-photon interface, a single photon transistor, and a deterministic cNOT gate....

  20. Charged-Exciton Complexes in Quantum Dots

    Institute of Scientific and Technical Information of China (English)

    XIE Wen-Fang

    2001-01-01

    It is known experimentally that stable charged-exciton complexes can exist in low-dimensional semiconductor nanostructures. Much less is known about the properties of such charged-exciton complexes since three-body problems are very difficult to be solved, even numerically. Here we introduce the correlated hyperspherical harmonics as basis functions to solve the hyperangular equation for negatively and positively charged excitons (trions) in a harmonic quantum dot. By using this method, we have calculated the energy spectra of the low-lying states of a charged exciton as a function of the radius of quantum dot. Based on symmetry analysis, the level crossover as the dot radius increases can be fully explained as the results of symmetry constraint.``

  1. Barrier Li Quantum Dots in Magnetic Fields

    Institute of Scientific and Technical Information of China (English)

    LIUYi-Min; LIXiao-Zhu; YANWen-Hong; BAOCheng-Guang

    2003-01-01

    The methods for the few-body system are introduced to investigate the states of the barrier Li quantum dots (QDs) in an arbitrary strength of magnetic field. The configuration, which consists of a positive ion located on the z-axis at a distaneed from the two-dimensional QD plane (the x-y plane) and three electrons in the dot plane bound by the positive ion, is called a barrier Li center. The system, which consists of three electrons in the dot plane bound by the ion,is called a barrier Li QD. The dependence of energy of the state of the barrier Li QD on an external magnetic field B and the distance d is obtained. The angular momentum L of the ground states is found to jump not only with the variation orB but also with d.

  2. Branch management into micropipeline joint dot

    Directory of Open Access Journals (Sweden)

    Dimitar Tyanev

    2011-11-01

    Full Text Available This paper considers problems related to hardware implementation of computational process with conditional jumps. Hardware refers to asynchronous pipeline organization at microoperational level. Exploration is dedicated to one of the tasks presented in (Tyanev, D., 2009 concerning to micropipeline controller design to control micropipeline stage into joint dot of branch algorithm. Joint dot is the point at which few preceding branches are combined. It appears inevitably into conditional jump structures and this is the reason for the actuality of its problem. Analysis of this new task is presented and request arbitration functioning principles are formulated for the incoming to joint dot requests. The arbiter is responsible for the fair choice on which depends steady peformance of separate pipeline brances. Paper also describes pipeline controller synthesis and analysis of its operation in two variants: about 2-phase and 4-phase data transfer protocol. The synthesized asynchronous arbiter scheme is invariant to the type of pipeline protocol.

  3. Epidemiological features of skeletal tuberculosis at an urban district tuberculosis centre.

    Science.gov (United States)

    Chopra, Rajat; Bhatt, Rama; Biswas, S K; Bhalla, R

    2016-04-01

    Skeletal tuberculosis is an important component of extra-pulmonary tuberculosis. It can lead to substantial morbidity and poses serious occupational and economic problem. We conducted a study in an urban District Tuberculosis Centre (DTC) to assess the burden and distribution of skeletal tuberculosis in the community. Our centre was catering to a population of 6-7 lakhs between 2007 and 2012. During this period, we treated 11,274 cases of tuberculosis. Out of these, 3086 (27.3%) were cases of extrapulmonary tuberculosis and 219 (1.94%) were cases of skeletal tuberculosis. Skeletal TB predominantly affects the young Indian population with incidence peaking in the second and third decades of life. 172 patients (78.5%) in our study were new cases. There were no drugs resistant (DRTB) skeletal TB cases till we concluded our study. Tuberculosis commonly involves joints more than long bones. The spinal column was the most commonly involved skeletal site affecting 62.6% of all cases. The rate of spinal TB in our study is much higher than that reported in literature. The high number of patients calls for close co-ordination between managing orthopaedic surgeons, treating physicians and DOT providers to ensure adequate patient care. PMID:27451817

  4. Optical properties of charged semiconductor quantum dots

    Science.gov (United States)

    Jha, Praket P.

    The effect of n-type doping on the luminescence properties of II-VI quantum dots is studied. The addition of two shells of CdS on CdSe quantum dots prevents the creation of surface traps and makes the system stable under reducing environment. The injection of electrons into films of quantum dots leads to lower photoluminescence (PL) efficiency, with the extent of quenching dependent on both the number and the quantum states of the spectator charges in the nanocrystal. It is found that a 1Pe electron is an eightfold better PL quencher than the 1Se electron. Reduced threshold for stimulated emission is also observed in doped CdSe/CdS films. Time resolved photoluminescence measurements are used to extract the recombination rates of a charged exciton, called trion. It is observed that the negative trion has a radiative rate ˜2.2 +/- 0.4x faster than a neutral exciton, while its non-radiative recombination rate is slower than the biexciton non-radiative recombination rate by a factor of 7.5 +/- 1.7. The knowledge of the recombination rates of the trion enables us to calculate the quantum yield of a negative trion to be ˜10% for the nanocrystals investigated in our work. This is larger than the off state quantum yield from a single quantum dot photoluminescence trajectory and eliminates the formation of negative trion as the possible reason for the PL blinking of single quantum dots. Single quantum dot electrochemistry has also been achieved. It is shown that by varying the Fermi level of the system electrons can be reversibly injected into and extracted out of single CdSe/CdS and CdSe/ZnS nanoparticles to modulate the photoluminescence.

  5. Tele-centres as a way of achieving universal access

    DEFF Research Database (Denmark)

    Falch, Morten; Anyimadu, Amos

    2003-01-01

    The success of tele-centres in Ghana is discussed. The tele-centres offer a low cost opportunity to empower local communities in developed and developing countries to meet the challenges of the information society. The tele-centres can also contribute more directly to the supply of non-commercial...

  6. Canadian Educational Development Centre Websites: More Ebb than Flow?

    Science.gov (United States)

    Simmons, Nicola

    2010-01-01

    This paper examines information portrayed on Canadian educational development (ED) centre websites and, in particular, whether information that corresponds to questions compiled from a literature search of ED centre practices is readily available from centre websites. This study phase is part of a larger national study of Canadian educational…

  7. Photoluminescence studies of single InGaAs quantum dots

    DEFF Research Database (Denmark)

    Leosson, Kristjan; Jensen, Jacob Riis; Hvam, Jørn Märcher

    1999-01-01

    Semiconductor quantum dots are considered a promising material system for future optical devices and quantum computers. We have studied the low-temperature photoluminescence properties of single InGaAs quantum dots embedded in GaAs. The high spatial resolution required for resolving single dots...

  8. Imaging vasculature and lymphatic flow in mice using quantum dots

    DEFF Research Database (Denmark)

    Ballou, Byron; Ernst, Lauren A.; Andreko, Susan;

    2009-01-01

    Quantum dots are ideal probes for fluorescent imaging of vascular and lymphatic tissues. On injection into appropriate sites, red- and near-infrared-emitting quantum dots provide excellent definition of vasculature, lymphoid organs, and lymph nodes draining both normal tissues and tumors. We detail...... methods for use with commercially available quantum dots and discuss common difficulties....

  9. AHE measurements of very thin films and nanosized dots

    NARCIS (Netherlands)

    Kikuchi, N.; Murillo, R.; Lodder, J.C.

    2005-01-01

    In this paper we present anomalous Hall effect analysis from very thin Co (0.5 nm) film, Co/Pt multilayers and large areas of nanosized dots as well as from a few magnetic dots having a diameter of 120 nm. The dot arrayis prepared from Co/Pt multilayer by using laser interference lithography (LIL) w

  10. Bright infrared LEDs based on colloidal quantum-dots

    KAUST Repository

    Sun, Liangfeng

    2013-01-01

    Record-brightness infrared LEDs based on colloidal quantum-dots have been achieved through control of the spacing between adjacent quantum-dots. By tuning the size of quantum-dots, the emission wavelengths can be tuned between 900nm and 1650nm. © 2013 Materials Research Society.

  11. Engineered Quantum Dot Single Photon Sources

    CERN Document Server

    Buckley, Sonia; Vuckovic, Jelena

    2012-01-01

    Fast, high efficiency, and low error single photon sources are required for implementation of a number of quantum information processing applications. The fastest triggered single photon sources to date have been demonstrated using epitaxially grown semiconductor quantum dots (QDs), which can be conveniently integrated with optical microcavities. Recent advances in QD technology, including demonstrations of high temperature and telecommunications wavelength single photon emission, have made QD single photon sources more practical. Here we discuss the applications of single photon sources and their various requirements, before reviewing the progress made on a quantum dot platform in meeting these requirements.

  12. Optical studies of capped quantum dots

    OpenAIRE

    Wuister, S.F.

    2005-01-01

    This thesis describes the synthesis and spectroscopy of CdSe and CdTe semiconductor quantum dots (QDs). The first chapter gives an introduction into the unique size dependent properties of semiconductor quantum dots. Highly luminescent QDs of CdSe and CdTe were prepared via a high temperature method in a glovebox. These QDs are soluble in organics but can be transferred into water or ethanol after exchange of the surfactants by various thiols (HS-R). For CdTe the exchange with thiols has a be...

  13. Cadmium telluride quantum dots advances and applications

    CERN Document Server

    Donegan, John

    2013-01-01

    Optical Properties of Bulk and Nanocrystalline Cadmium Telluride, Núñez Fernández and M.I. VasilevskiyAqueous Synthesis of Colloidal CdTe Nanocrystals, V. Lesnyak, N. Gaponik, and A. EychmüllerAssemblies of Thiol-Capped CdTe Nanocrystals, N. GaponikFörster Resonant Energy Transfer in CdTe Nanocrystal Quantum Dot Structures, M. Lunz and A.L. BradleyEmission of CdTe Nanocrystals Coupled to Microcavities, Y.P. Rakovich and J.F. DoneganBiological Applications of Cadmium Telluride Semiconductor Quantum Dots, A. Le Cign

  14. Resonant tunneling in graphene pseudomagnetic quantum dots.

    Science.gov (United States)

    Qi, Zenan; Bahamon, D A; Pereira, Vitor M; Park, Harold S; Campbell, D K; Neto, A H Castro

    2013-06-12

    Realistic relaxed configurations of triaxially strained graphene quantum dots are obtained from unbiased atomistic mechanical simulations. The local electronic structure and quantum transport characteristics of y-junctions based on such dots are studied, revealing that the quasi-uniform pseudomagnetic field induced by strain restricts transport to Landau level- and edge state-assisted resonant tunneling. Valley degeneracy is broken in the presence of an external field, allowing the selective filtering of the valley and chirality of the states assisting in the resonant tunneling. Asymmetric strain conditions can be explored to select the exit channel of the y-junction.

  15. Mitigation of quantum dot cytotoxicity by microencapsulation.

    Directory of Open Access Journals (Sweden)

    Amelia Romoser

    Full Text Available When CdSe/ZnS-polyethyleneimine (PEI quantum dots (QDs are microencapsulated in polymeric microcapsules, human fibroblasts are protected from acute cytotoxic effects. Differences in cellular morphology, uptake, and viability were assessed after treatment with either microencapsulated or unencapsulated dots. Specifically, QDs contained in microcapsules terminated with polyethylene glycol (PEG mitigate contact with and uptake by cells, thus providing a tool to retain particle luminescence for applications such as extracellular sensing and imaging. The microcapsule serves as the "first line of defense" for containing the QDs. This enables the individual QD coating to be designed primarily to enhance the function of the biosensor.

  16. The "Magic" of Tutorial Centres in Hong Kong: An Analysis of Media Marketing and Pedagogy in a Tutorial Centre

    Science.gov (United States)

    Koh, Aaron

    2014-01-01

    Why do more than three-quarters of Hong Kong's senior secondary students flock to tutorial centres like moths to light? What is the "magic" that is driving the popularity of the tutorial centre enterprise? Indeed, looking at the ongoing boom of tutorial centres in Hong Kong (there are almost 1,000 of them), it is difficult not to ask…

  17. Bhabha Atomic Research Centre: annual report 1988

    International Nuclear Information System (INIS)

    The research and development (R and D) work carried out in the Bhabha Atomic Research Centre (BARC), Bombay during 1988 is summarised and presented in the sections entitled Physical Sciences, Chemical Sciences, Materials and Materials Science, Radioisotopes, Reactors, Fuel cycle, Radiological Safety and Protection, Electronics and Instrumentation, Engineering Services, Life Sciences and General. At the end of each section a list of publications is also given. The R and D work of the outstation units of BARC, namely, Nuclear Research Laboratory, Srinagar; High Altitute Research Laboratory, Gulmarg and Variable Energy Cyclotron Centre, Calcutta are also described in this report. Some of the highlights of the work during the year are: (1) Medium Energy Heavy Ion Accelerator (MEHIA) facility set up jointly by BARC and the Tata Institute of Fundamental Research (TIFR) at TIFR premises became fully operational in September 1988. A number of new compositions of high temperature supconducting materials were synthesized. The highest transition temperature achieved was 125 K. Research work to improve the quality of sintered uranium oxide pellets achieved the purpose. Nuclear fuels were fabricated by using sol-gel process. R and D work for 235 MWe and 500 MWe PHWR type reactors is continuing. Conceptual design of the fuel handling system for the prototype fast breeder reactor was finalised. 233U+Al alloy fuel for Kamini reactor was fabricated. Progress has been made in industrial applications of enzymes. Various applications of radioisotopes are being continued. Certain technologies and processes developed in the Centre were transferred to commercial agencies for large scale exploitation. (M.G.B.)

  18. Human-centred approaches in slipperiness measurement

    Science.gov (United States)

    Grönqvist, Raoul; Abeysekera, John; Gard, Gunvor; Hsiang, Simon M.; Leamon, Tom B.; Newman, Dava J.; Gielo-Perczak, Krystyna; Lockhart, Thurmon E.; Pai, Clive Y.-C.

    2010-01-01

    A number of human-centred methodologies—subjective, objective, and combined—are used for slipperiness measurement. They comprise a variety of approaches from biomechanically-oriented experiments to psychophysical tests and subjective evaluations. The objective of this paper is to review some of the research done in the field, including such topics as awareness and perception of slipperiness, postural and balance control, rating scales for balance, adaptation to slippery conditions, measurement of unexpected movements, kinematics of slipping, and protective movements during falling. The role of human factors in slips and falls will be discussed. Strengths and weaknesses of human-centred approaches in relation to mechanical slip test methodologies are considered. Current friction-based criteria and thresholds for walking without slipping are reviewed for a number of work tasks. These include activities such as walking on a level or an inclined surface, running, stopping and jumping, as well as stair ascent and descent, manual exertion (pushing and pulling, load carrying, lifting) and particular concerns of the elderly and mobility disabled persons. Some future directions for slipperiness measurement and research in the field of slips and falls are outlined. Human-centred approaches for slipperiness measurement do have many applications. First, they are utilized to develop research hypotheses and models to predict workplace risks caused by slipping. Second, they are important alternatives to apparatus-based friction measurements and are used to validate such methodologies. Third, they are used as practical tools for evaluating and monitoring slip resistance properties of foot wear, anti-skid devices and floor surfaces. PMID:11794763

  19. Biological Inspiration in Human Centred Robotics

    Institute of Scientific and Technical Information of China (English)

    HUHuo-sheng; LIUJin-dong; CalderonCarlosA

    2004-01-01

    Human centred robotics (HCR) concerns with the development of various kinds of intelligent systems and robots that will be used in environments coexisting with humans. These systems and robots will be interactive and useful assistants/companions for people in different ages, situations, activities and environments in order to improve the quality of life. This paper presents the autors' current research work toward the development of advanced theory and technologies for HCR applications, based on inspiration from biological systems. More specifically, both bio-mimetic system modelling and robot learning by imitation are discussed respectively, and some preliminary results are demonstrated.

  20. The INTEGRAL science data centre (ISDC)

    DEFF Research Database (Denmark)

    Courvoisier, T.J.L.; Walter, Rasmus; Beckmann, V.;

    2003-01-01

    The INTEGRAL Science Data Centre (ISDC) provides the INTEGRAL data and means to analyse them to the scientific community. The ISDC runs a gamma ray burst alert system that provides the position of gamma ray bursts on the sky within seconds to the community. It operates a quick-look analysis...... of the data within few hours that detects new and unexpected sources as well as it monitors the instruments. The ISDC processes the data through a standard analysis the results of which are provided to the observers together with their data....

  1. Hunting for hardware changes in data centres

    International Nuclear Information System (INIS)

    With many servers and server parts the environment of warehouse sized data centres is increasingly complex. Server life-cycle management and hardware failures are responsible for frequent changes that need to be managed. To manage these changes better a project codenamed “hardware hound” focusing on hardware failure trending and hardware inventory has been started at CERN. By creating and using a hardware oriented data set - the inventory - with detailed information on servers and their parts as well as tracking changes to this inventory, the project aims at, for example, being able to discover trends in hardware failure rates.

  2. A study of the lunisolar secular resonance $2dot{omega}+dot{Omega}=0$

    Directory of Open Access Journals (Sweden)

    Alessandra eCelletti

    2016-03-01

    Full Text Available The dynamics of small bodies around the Earth has gained a renewed interest,since the awareness of the problems that space debris can cause in thenearby future. A relevant role in space debris is played by lunisolarsecular resonances, which might contribute to an increase of the orbitalelements, typically of the eccentricity. We concentrate our attention onthe lunisolar secular resonance described by the relation$2dot{omega}+dot{Omega}=0$, where $omega$ and $Omega$ denotethe argument of perigee and the longitude of the ascending node of the space debris.We introduce three different models with increasing complexity. We show that the growth in eccentricity, as observed in space debris located in the MEO region at the inclination about equal to $56^circ$, can be explained as a natural effect of the secular resonance $2dot{omega}+dot{Omega}=0$, while the chaotic variations of the orbital parameters are the result of interaction and overlapping of nearby resonances.

  3. A study of the lunisolar secular resonance 2dot{ω}+dot{Ω}=0

    Science.gov (United States)

    Celletti, Alessandra; Gales, Catalin

    2016-03-01

    The dynamics of small bodies around the Earth has gained a renewed interest, since the awareness of the problems that space debris can cause in the nearby future. A relevant role in space debris is played by lunisolar secular resonances, which might contribute to an increase of the orbital elements, typically of the eccentricity. We concentrate our attention on the lunisolar secular resonance described by the relation 2dot{ω}+dot{Ω}=0, where ω and Ω denote the argument of perigee and the longitude of the ascending node of the space debris. We introduce three different models with increasing complexity. We show that the growth in eccentricity, as observed in space debris located in the MEO region at the inclination about equal to 56°, can be explained as a natural effect of the secular resonance 2dot{ω}+dot{Ω}=0, while the chaotic variations of the orbital parameters are the result of interaction and overlapping of nearby resonances.

  4. A study of the lunisolar secular resonance $2\\dot{\\omega}+\\dot{\\Omega}=0$

    CERN Document Server

    Celletti, Alessandra

    2016-01-01

    The dynamics of small bodies around the Earth has gained a renewed interest, since the awareness of the problems that space debris can cause in the nearby future. A relevant role in space debris is played by lunisolar secular resonances, which might contribute to an increase of the orbital elements, typically of the eccentricity. We concentrate our attention on the lunisolar secular resonance described by the relation $2\\dot{\\omega}+\\dot{\\Omega}=0$, where $\\omega$ and $\\Omega$ denote the argument of perigee and the longitude of the ascending node of the space debris. We introduce three different models with increasing complexity. We show that the growth in eccentricity, as observed in space debris located in the MEO region at the inclination about equal to $56^\\circ$, can be explained as a natural effect of the secular resonance $2\\dot{\\omega}+\\dot{\\Omega}=0$, while the chaotic variations of the orbital parameters are the result of interaction and overlapping of nearby resonances.

  5. Electrically addressing a single self-assembled quantum dot

    CERN Document Server

    Ellis, D J P; Atkinson, P; Ritchie, D A; Shields, A J

    2006-01-01

    We report on the use of an aperture in an aluminum oxide layer to restrict current injection into a single self-assembled InAs quantum dot, from an ensemble of such dots within a large mesa. The insulating aperture is formed through the wet-oxidation of a layer of AlAs. Under photoluminescence we observe that only one quantum dot in the ensemble exhibits a Stark shift, and that the same single dot is visible under electroluminescence. Autocorrelation measurements performed on the electroluminescence confirm that we are observing emission from a single quantum dot.

  6. The Influence of Formulating a Damping Solution on Dot Gain

    Directory of Open Access Journals (Sweden)

    Povilas Mikalainis

    2011-02-01

    Full Text Available Difference in dot gain using various additives to the damping solution was investigated on two offset web presses. Dot gain was measured using a densitometer and calculated considering CIE L*a*b* coordinates. It was found that while using a non alcohol additive instead of the alcohol one, dot gain became smaller and printing stability was lower. Changes in dot gain depend on the ink that may vary in colours. The influence of changes in dot gain on the colour was determined. Besides, it was found that differences in colour were unacceptable in many cases.Article in Lithuanian

  7. Synthesis of CdSe quantum dots for quantum dot sensitized solar cell

    Energy Technology Data Exchange (ETDEWEB)

    Singh, Neetu, E-mail: singh.neetu1985@gmail.com; Kapoor, Avinashi [Department of Electronic Science, University of Delhi South Campus, New Delhi-110 021 (India); Kumar, Vinod [Department of Physics, University of the Free State, Bloemfontein, ZA9300 (South Africa); Mehra, R. M. [School of Engineering and Technology, Sharda University, Greater Noida-201 306, U.P. (India)

    2014-04-24

    CdSe Quantum Dots (QDs) of size 0.85 nm were synthesized using chemical route. ZnO based Quantum Dot Sensitized Solar Cell (QDSSC) was fabricated using CdSe QDs as sensitizer. The Pre-synthesized QDs were found to be successfully adsorbed on front ZnO electrode and had potential to replace organic dyes in Dye Sensitized Solar Cells (DSSCs). The efficiency of QDSSC was obtained to be 2.06 % at AM 1.5.

  8. Synthesis of CdSe quantum dots for quantum dot sensitized solar cell

    International Nuclear Information System (INIS)

    CdSe Quantum Dots (QDs) of size 0.85 nm were synthesized using chemical route. ZnO based Quantum Dot Sensitized Solar Cell (QDSSC) was fabricated using CdSe QDs as sensitizer. The Pre-synthesized QDs were found to be successfully adsorbed on front ZnO electrode and had potential to replace organic dyes in Dye Sensitized Solar Cells (DSSCs). The efficiency of QDSSC was obtained to be 2.06 % at AM 1.5

  9. The Australian centre for RF bioeffects research (ACRBR) - an NHMRC centre of research excellence

    International Nuclear Information System (INIS)

    Full text: The Australian Centre for Radiofrequency Bioeffects Research (ACRBR) is a newly established multi-institutional research centre which seeks to research questions pertaining to possible health effects of exposure to radiofrequency devices, such as mobile phones and which is funded under the Australian National Health and Medical Research Council (NHMRC) Centres of Research Excellence funding program. The Centre of Research Excellence in Electromagnetic Energy is combining the efforts of engineers, epidemiologists, physicists, psychophysiologists and veterinary pathologists from RMIT University, the Institute of Medical and Veterinary Science in South Australia (IMVS), Monash University, Swinburne University of Technology and Telstra Research Laboratories (TRL). The centre is funded at $2.5 M over five years and will undertake a program of research to address the issue of exposure to radiofrequency (RF) devices and health. It will also train new scientists, keep the community informed of ongoing developments and help the development of government policies in this area of considerable public concern. The 5-year program has the following components: Neurobiology: One important area where there is a perceived research gap is in the area of potential neurological effects, which will hence be a major focus of this Centre. The proposed studies range from in vitro and in vivo research studies of RF effects on neuron and neural system functioning in rodents, to that of RF effects on simple neural function, cognition and subjective report in humans. The latter series of studies have been developed to account for the consensus view that more emphasis needs to be placed on possible differences in RF population sensitivity (e.g. youth versus aged, and ' electromagnetic hypersensitives'). Epidemiological studies are an important tool in studying the impact on public health from exposure of whole populations to modern radio technologies. Cancer outcomes in this area of

  10. Ostwald's ripening of nanostructures with quantum dots

    CERN Document Server

    Vengrenovich, R D; Yarema, S V

    2001-01-01

    The scenario of quantum dots shaping during ripening three-dimensional islands obtained by heteroepitaxy in a Stranski-Krastanow mode, is offered. It is shown that throughout the growth of dislocations with their subsequent separation from the island bottom, the size distribution function becomes narrower with noticeable diminishing the dispersion. The possible reasons for signal attenuation of Ostwald's ripening islands are analyzed

  11. Ostwald's ripening of nanostructures with quantum dots

    International Nuclear Information System (INIS)

    The scenario of quantum dots shaping during ripening three-dimensional islands obtained by heteroepitaxy in a Stranski-Krastanow mode, is offered. It is shown that throughout the growth of dislocations with their subsequent separation from the island bottom, the size distribution function becomes narrower with noticeable diminishing the dispersion. The possible reasons for signal attenuation of Ostwald's ripening islands are analyzed

  12. Saturating optical resonances in quantum dots

    Science.gov (United States)

    Nair, Selvakumar V.; Rustagi, K. C.

    Optical bistability in quantum dots, recently proposed by Chemla and Miller, is studied in a two-resonance model. We show that for such classical electromagnetic resonances the applicability of a two-resonance model is far more restrictive than for those in atoms.

  13. Quantum dot devices for optical communications

    DEFF Research Database (Denmark)

    Mørk, Jesper

    2005-01-01

    Semiconductor quantum dots are often described as "artificial atoms": They are small nanometre-sized structures in which electrons only are allowed to exist at certain discrete levels due to size quantization, thus allowing the engineering of fundamental properties such as the coupling to light. ...

  14. Single Molecule Applications of Quantum Dots

    DEFF Research Database (Denmark)

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

    2013-01-01

    Fluorescent nanocrystals composed of semiconductor materials were first introduced for biological applications in the late 1990s. The focus of this review is to give a brief survey of biological applications of quantum dots (QDs) at the single QD sensitivity level. These are described as follows: 1...

  15. Optical anisotropy in vertically coupled quantum dots

    DEFF Research Database (Denmark)

    Yu, Ping; Langbein, Wolfgang Werner; Leosson, Kristjan;

    1999-01-01

    We have studied the polarization of surface and edge-emitted photoluminescence (PL) from structures with vertically coupled In0.5Ga0.5As/GaAs quantum dots (QD's) grown by molecular beam epitaxy. The PL polarization is found to be strongly dependent on the number of stacked layers. While single...

  16. Decoherence in Nearly-Isolated Quantum Dots

    DEFF Research Database (Denmark)

    Folk, J.; M. Marcus, C.; Harris jr, J.

    2000-01-01

    Decoherence in nearly-isolated GaAs quantum dots is investigated using the change in average Coulomb blockade peak height upon breaking time-reversal symmetry. The normalized change in average peak height approaches the predicted universal value of 1/4 at temperatures well below the single...

  17. Producing Quantum Dots by Spray Pyrolysis

    Science.gov (United States)

    Banger, Kulbinder; Jin, Michael H.; Hepp, Aloysius

    2006-01-01

    An improved process for making nanocrystallites, commonly denoted quantum dots (QDs), is based on spray pyrolysis. Unlike the process used heretofore, the improved process is amenable to mass production of either passivated or non-passivated QDs, with computer control to ensure near uniformity of size.

  18. System and method for making quantum dots

    KAUST Repository

    Bakr, Osman M.

    2015-05-28

    Embodiments of the present disclosure provide for methods of making quantum dots (QDs) (passivated or unpassivated) using a continuous flow process, systems for making QDs using a continuous flow process, and the like. In one or more embodiments, the QDs produced using embodiments of the present disclosure can be used in solar photovoltaic cells, bio-imaging, IR emitters, or LEDs.

  19. Amphoteric CdSe nanocrystalline quantum dots.

    Science.gov (United States)

    Islam, Mohammad A

    2008-06-25

    The nanocrystal quantum dot (NQD) charge states strongly influence their electrical transport properties in photovoltaic and electroluminescent devices, optical gains in NQD lasers, and the stability of the dots in thin films. We report a unique electrostatic nature of CdSe NQDs, studied by electrophoretic methods. When we submerged a pair of metal electrodes, in a parallel plate capacitor configuration, into a dilute solution of CdSe NQDs in hexane, and applied a DC voltage across the pair, thin films of CdSe NQDs were deposited on both the positive and the negative electrodes. Extensive characterizations including scanning electron microscopy (SEM), atomic force microscopy (AFM), Fourier transform infrared (FTIR) and Raman studies revealed that the films on both the positive and the negative electrodes were identical in every respect, clearly indicating that: (1) a fraction (<1%) of the CdSe NQDs in free form in hexane solution are charged and, more importantly, (2) there are equal numbers of positive and negative CdSe NQDs in the hexane solution. Experiments also show that the number of deposited dots is at least an order of magnitude higher than the number of initially charged dots, indicating regeneration. We used simple thermodynamics to explain such amphoteric nature and the charging/regeneration of the CdSe NQDs.

  20. Quantum Dot Devices for Optical Signal Processing

    DEFF Research Database (Denmark)

    Chen, Yaohui

    with other semiconductor materials. The understanding of such properties is important in order to improve the performance of existing devices and to trigger the development of new semiconductor devices for dierent optical signal processing functionalities in the future. We present a detailed quantum dot...

  1. Competing interactions in semiconductor quantum dots

    NARCIS (Netherlands)

    R. van den Berg; G.P. Brandino; O. El Araby; R.M. Konik; V. Gritsev; J.S. Caux

    2014-01-01

    We introduce an integrability-based method enabling the study of semiconductor quantum dot models incorporating both the full hyperfine interaction as well as a mean-field treatment of dipole-dipole interactions in the nuclear spin bath. By performing free-induction decay and spin-echo simulations w

  2. Enabling biomedical research with designer quantum dots

    NARCIS (Netherlands)

    Tomczak, N.; Janczewski, D.; Dorokhin, D.V.; Han, M-Y; Vancso, G.J.; Navarro, Melba; Planell, Josep A.

    2012-01-01

    Quantum Dots (QDs) are a new class of semiconductor nanoparticulate luminophores, which are actively researched for novel applications in biology and nanomedicine. In this review, the recent progress in the design and applications of QD labels for in vitro and in vivo imaging of cells is presented.

  3. Quantum dot waveguides: ultrafast dynamics and applications

    DEFF Research Database (Denmark)

    Chen, Yaohui; Mørk, Jesper

    2009-01-01

    In this paper we analyze, based on numerical simulations, the dynamics of semiconductor devices incorporating quantum dots (QDs). In particular we emphasize the unique ultrafast carrier dynamics occurring between discrete QD bound states, and its influence on QD semiconductor optical amplifiers...

  4. Tunneling Processes in Optically Excited Quantum Dots

    Institute of Scientific and Technical Information of China (English)

    LI Xiu-Ping; WEI Hua-Rong; XU Li-Ping; GONG Jian-Ping; YAN Wei-Xian

    2011-01-01

    The single-electron tunneling processes in optically excited coupled quantum dots can be divided into two parts: the electron and the hole parts, which are analytically obtained in the framework of the Keldysh formalism. The tunneling process is selective tunneling, which results in dark tunneling states. The tunneling currents are co-determined by the resonance energies and probability distributions of the particular quantum channels defined by the electron-hole complex resonant states.%The single-electron tunneling processes in optically excited coupled quantum dots can be divided into two parts:the electron and the hole parts,which are analytically obtained in the framework of the Keldysh formalism.The tunneling process is selective tunneling,which results in dark tunneling states.The tunneling currents are co-determined by the resonance energies and probability distributions of the particular quantum channels defined by the electron-hole complex resonant states.Probing the fine-energy structure of the exciton complexes[1-10] in an optically excited quantum dot is an important way of exploring new mechanisms in nanostructures.Single electron tunneling (SET) devices consisting of a central quantum dot (QD) and a tunneling coupled source and drain have become important optoelectronic nano-devices.[11,12

  5. Inter-dot strain field effect on the optoelectronic properties of realistic InP lateral quantum-dot molecules

    International Nuclear Information System (INIS)

    We report on numerical simulations of InP surface lateral quantum-dot molecules on In0.48Ga0.52 P buffer, using a model strictly derived by experimental results by extrapolation of the molecules shape from atomic force microscopy images. Our study has been inspired by the comparison of a photoluminescence spectrum of a high-density InP surface quantum dot sample with a numerical ensemble average given by a weighted sum of simulated single quantum-dot spectra. A lack of experimental optical response from the smaller dots of the sample is found to be due to strong inter-dot strain fields, which influence the optoelectronic properties of lateral quantum-dot molecules. Continuum electromechanical, k→·p→ bandstructure, and optical calculations are presented for two different molecules, the first composed of two dots of nearly identical dimensions (homonuclear), the second of two dots with rather different sizes (heteronuclear). We show that in the homonuclear molecule the hydrostatic strain raises a potential barrier for the electrons in the connection zone between the dots, while conversely the holes do not experience any barrier, which considerably increases the coupling. Results for the heteronuclear molecule show instead that its dots do not appear as two separate and distinguishable structures, but as a single large dot, and no optical emission is observed in the range of higher energies where the smaller dot is supposed to emit. We believe that in samples of such a high density the smaller dots result as practically incorporated into bigger molecular structures, an effect strongly enforced by the inter-dot strain fields, and consequently it is not possible to experimentally obtain a separate optical emission from the smaller dots

  6. Inter-dot strain field effect on the optoelectronic properties of realistic InP lateral quantum-dot molecules

    Energy Technology Data Exchange (ETDEWEB)

    Barettin, Daniele, E-mail: Daniele.Barettin@uniroma2.it; Auf der Maur, Matthias [Department of Electronic Engineering, University of Rome “Tor Vergata,” Via del Politecnico 1, 00133, Rome (Italy); De Angelis, Roberta; Prosposito, Paolo; Casalboni, Mauro [Department of Industrial Engineering, University of Rome Tor Vergata, Via del Politecnico 1 00133 Rome, Italy and INSTM, Unitá di ricerca dell' Universitá di Roma “Tor Vergata,” Via della Ricerca Scientifica 1, 00133, Rome (Italy); Pecchia, Alessandro [CNR-ISMN, via Salaria Km. 29.300, 00017 Monterotondo, Rome (Italy)

    2015-03-07

    We report on numerical simulations of InP surface lateral quantum-dot molecules on In{sub 0.48}Ga{sub 0.52 }P buffer, using a model strictly derived by experimental results by extrapolation of the molecules shape from atomic force microscopy images. Our study has been inspired by the comparison of a photoluminescence spectrum of a high-density InP surface quantum dot sample with a numerical ensemble average given by a weighted sum of simulated single quantum-dot spectra. A lack of experimental optical response from the smaller dots of the sample is found to be due to strong inter-dot strain fields, which influence the optoelectronic properties of lateral quantum-dot molecules. Continuum electromechanical, k{sup →}·p{sup →} bandstructure, and optical calculations are presented for two different molecules, the first composed of two dots of nearly identical dimensions (homonuclear), the second of two dots with rather different sizes (heteronuclear). We show that in the homonuclear molecule the hydrostatic strain raises a potential barrier for the electrons in the connection zone between the dots, while conversely the holes do not experience any barrier, which considerably increases the coupling. Results for the heteronuclear molecule show instead that its dots do not appear as two separate and distinguishable structures, but as a single large dot, and no optical emission is observed in the range of higher energies where the smaller dot is supposed to emit. We believe that in samples of such a high density the smaller dots result as practically incorporated into bigger molecular structures, an effect strongly enforced by the inter-dot strain fields, and consequently it is not possible to experimentally obtain a separate optical emission from the smaller dots.

  7. External Electric Field Effect on Hydrogenic Donor Impurity in Zinc-Blende InGaN Quantum Dot

    Institute of Scientific and Technical Information of China (English)

    JIANG Li-Ming; WANG Hai-Long; WU Hui-Ting; GONG Qian; FENG Song-Lin

    2008-01-01

    @@ The binding energy of a hydrogenic donor impurity in zinc-blende (ZB) InGaN quantum dot (QD) is calculatedin the framework of effective-mass envelope-function theory using the plane wave basis. It is shown that the donor binding energy is highly dependent on the impurity position, QD size and the external electric field. The symmetry of the electron probability distribution is broken and the maximum of the donor binding energy is shifted from the centre of QD in the presence of the external electric field. The degenerating energy levels for symmetrical positions with respect to the centre of QD are split. The splitting increases with the increase of QD height while the splitting increases up to a maximum value and then decreases with the increase of QD radius.

  8. Annealing-induced change in quantum dot chain formation mechanism

    Energy Technology Data Exchange (ETDEWEB)

    Park, Tyler D.; Colton, John S.; Farrer, Jeffrey K. [Department of Physics and Astronomy, Brigham Young University, Provo UT 84602 (United States); Yang, Haeyeon [Department of Nanoscience and Nanoengineering, South Dakota School of Mines and Technology, Rapid City, SD 57701 (United States); Kim, Dong Jun [IPG Photonics Corporation, Oxford, MA 01540 (United States)

    2014-12-15

    Self-assembled InGaAs quantum dot chains were grown using a modified Stranski-Krastanov method in which the InGaAs layer is deposited under a low growth temperature and high arsenic overpressure, which suppresses the formation of dots until a later annealing process. The dots are capped with a 100 nm GaAs layer. Three samples, having three different annealing temperatures of 460°C, 480°C, and 500°C, were studied by transmission electron microscopy. Results indicate two distinct types of dot formation processes: dots in the 460°C and 480°C samples form from platelet precursors in a one-to-one ratio whereas the dots in the sample annealed at 500°C form through the strain-driven self-assembly process, and then grow larger via an additional Ostwald ripening process whereby dots grow into larger dots at the expense of smaller seed islands. There are consequently significant morphological differences between the two types of dots, which explain many of the previously-reported differences in optical properties. Moreover, we also report evidence of indium segregation within the dots, with little or no indium intermixing between the dots and the surrounding GaAs barrier.

  9. Annealing-induced change in quantum dot chain formation mechanism

    Science.gov (United States)

    Park, Tyler D.; Colton, John S.; Farrer, Jeffrey K.; Yang, Haeyeon; Kim, Dong Jun

    2014-12-01

    Self-assembled InGaAs quantum dot chains were grown using a modified Stranski-Krastanov method in which the InGaAs layer is deposited under a low growth temperature and high arsenic overpressure, which suppresses the formation of dots until a later annealing process. The dots are capped with a 100 nm GaAs layer. Three samples, having three different annealing temperatures of 460°C, 480°C, and 500°C, were studied by transmission electron microscopy. Results indicate two distinct types of dot formation processes: dots in the 460°C and 480°C samples form from platelet precursors in a one-to-one ratio whereas the dots in the sample annealed at 500°C form through the strain-driven self-assembly process, and then grow larger via an additional Ostwald ripening process whereby dots grow into larger dots at the expense of smaller seed islands. There are consequently significant morphological differences between the two types of dots, which explain many of the previously-reported differences in optical properties. Moreover, we also report evidence of indium segregation within the dots, with little or no indium intermixing between the dots and the surrounding GaAs barrier.

  10. Annealing-induced change in quantum dot chain formation mechanism

    Directory of Open Access Journals (Sweden)

    Tyler D. Park

    2014-12-01

    Full Text Available Self-assembled InGaAs quantum dot chains were grown using a modified Stranski-Krastanov method in which the InGaAs layer is deposited under a low growth temperature and high arsenic overpressure, which suppresses the formation of dots until a later annealing process. The dots are capped with a 100 nm GaAs layer. Three samples, having three different annealing temperatures of 460°C, 480°C, and 500°C, were studied by transmission electron microscopy. Results indicate two distinct types of dot formation processes: dots in the 460°C and 480°C samples form from platelet precursors in a one-to-one ratio whereas the dots in the sample annealed at 500°C form through the strain-driven self-assembly process, and then grow larger via an additional Ostwald ripening process whereby dots grow into larger dots at the expense of smaller seed islands. There are consequently significant morphological differences between the two types of dots, which explain many of the previously-reported differences in optical properties. Moreover, we also report evidence of indium segregation within the dots, with little or no indium intermixing between the dots and the surrounding GaAs barrier.

  11. A novel POSS-coated quantum dot for biological application

    Directory of Open Access Journals (Sweden)

    Rizvi SB

    2012-08-01

    Full Text Available Sarwat B Rizvi,1 Lara Yildirimer,1 Shirin Ghaderi,1 Bala Ramesh,1 Alexander M Seifalian,1,2 Mo Keshtgar1,21UCL Centre for Nanotechnology and Regenerative Medicine, Division of Surgery and Interventional Science, University College London, United Kingdom; 2Royal Free Hampstead NHS Trust Hospital, London, United KingdomAbstract: Quantum dots (QDs are fluorescent semiconductor nanocrystals that have the potential for major advancements in the field of nanomedicine through their unique photophysical properties. They can potentially be used as fluorescent probes for various biomedical imaging applications, including cancer localization, detection of micrometastasis, image guided surgery, and targeted drug delivery. Their main limitation is toxicity, which requires a biologically compatible surface coating to shield the toxic core from the surrounding environment. However, this leads to an increase in QD size that may lead to problems of excretion and systemic sequestration. We describe a one pot synthesis, characterization, and in vitro cytotoxicity of a novel polyhedral oligomeric silsesquioxane (POSS-coated CdTe-cored QD using mercaptosuccinic acid (MSA and D-cysteine as stabilizing agents. Characterization was performed using transmission electron microscopy Fourier transform infrared spectroscopy, and photoluminescence studies. POSS-coated QDs demonstrated high colloidal stability and enhanced photostability on high degrees of ultraviolet (UV excitation compared to QDs coated with MSA and D-cysteine alone (P value < 0.05. In vitro toxicity studies showed that both POSS and MSA-QDs were significantly less toxic than ionized salts of Cd+2 and Te-2. Confocal microscopy confirmed high brightness of POSS-QDs in cells at both 1 and 24 hours, indicating that these QDs are rapidly taken up by cells and remain photostable in a biological environment. We therefore conclude that a POSS coating confers biological compatibility, photostability, and colloidal

  12. Information validation tool for technical support centres

    International Nuclear Information System (INIS)

    The French National Emergency Organisation relies on the expert advice given by the different Technical Support Centres (EDF/SEPTEN, CEA/IPSN, Framatome). For several years a great effort has been made to improve tools. The first generation was mainly concerned with computational aids such as real-time plant data acquisition and visualisation, break size calculations, containment release estimations... These tools were presented at the OECD NEA Specialist Meeting in 1993. Currently work is performed in the field of validation of information available to the Technical Support Centres. The three partners (EDF, CEA and Framatome) have developed a prototype implementing the diagnosis and the quality of the information pertaining to the 3D/3P method. The philosophy of this tool is to present to the expert a set of essential information (e.g. state of the fuel barrier, primary water inventory...) for the diagnosis with a confidence level associated to each information and the adequate explications. In fact the expert has not only to know the diagnosis but also how reliable the information is and why. Subsequently, the algorithms used to elaborate the diagnoses and the confidence factor have to be simple enough so that the user is able to consult the explanations in a fast and easy way. The paper details the three-step process to elaborate the diagnosis and the confidence factor

  13. ALICE opens its new nerve centre

    CERN Multimedia

    Antonella Del Rosso

    2014-01-01

    Twenty-nine fully equipped and ergonomic workstations, one meeting area and 11 large format screens in a completely refurbished room: the ALICE Run Control Centre (ARC) implements the best and newest solutions for its shift workers and expert operators, including access for persons with reduced mobility and very soon a magic window for Point 2 visitors.   The ALICE Run Control Centre. “Our initial intention was just to optimise the old layout,” says Federico Ronchetti from Laboratori Nazionali di Frascati (Italy), a CERN scientific associate currently appointed as ALICE Run Coordinator and person in charge of the ALICE Consolidation Task Force. “However, during the review process, we carried out a study of all the existing control rooms at CERN and became aware we needed a radical change. Hence we started planning a complete redesign of the workspace.” Designed and equipped over many years, the old ALICE control room did not have enough space to fit al...

  14. KNMI Data Centre: Easy access for all

    Science.gov (United States)

    van de Vegte, John; Som de Cerff, Wim; Plieger, Maarten; de Vreede, Ernst; Sluiter, Raymond; Willem Noteboom, Jan; van der Neut, Ian; Verhoef, Hans; van Versendaal, Robert; van Binnendijk, Martin; Kalle, Henk; Knopper, Arthur; Spit, Jasper; Mastop, Joeri; Klos, Olaf; Calis, Gijs; Ha, Siu-Siu; van Moosel, Wim; Klein Ikkink, Henk-Jan; Tosun, Tuncay

    2013-04-01

    KNMI is the Dutch institute for weather, climate research and seismology. It disseminates weather information to the public at large, the government, aviation and the shipping industry in the interest of safety, the economy and a sustainable environment. To gain insight into long-term developments KNMI conducts research on climate change. Making the knowledge, data and information on hand at KNMI accessible is one core activity. A huge part of the KNMI information is from numerical models, insitu sensor networks and remote sensing satellites. This digital collection is mostly internal only available and is a collection of non searchable , non standardized file formats, lacking documentation and has no references to scientific publications. With the KNMI Data Centre (KDC) project these issues are tackled. In the project a user driven development approach with SCRUM was chosen to get maximum user involvement in a relative short development timeframe. Building on open standards and proven open source technology (which includes in-house developed software like ADAGUC WMS and Portal) resulted in a first release in December 2012 This presentation will focus on the aspects of KDC relating to its technical challenges, the development strategy and the initial usage results of the data centre.

  15. Bhabha Atomic Research Centre annual report : 1989

    International Nuclear Information System (INIS)

    The main thrust of the various research and development (R and D) activities of the Bhabha Atomic Research Centre (BARC), Bombay, is towards the implementation of India's nuclear power programme. To that end, its R and D activities cover the entire nuclear fuel cycle, reactor technology; applications of radioisotopes and radiations in agriculture, medicine and industries; and radiation protection in nuclear installations. The report presents in summarised form the R and D activities carried out during 1989 in the chapters entitled: Physical Sciences, Chemical Sciences, Materials and Materials Sciences, Radioisotopes, Reactors, Fuel Cycle, Radiological Safety and Protection, Electronics and Instrumentation, Engineering Services, Life Sciences and General. At the end of each chapter, a list of publications by the staff scientists in the corresponding subject field is given. The list includes published journal articles and technical reports, and papers presented at conferences, symposia etc. The report also covers the R and D activities of the outstation units of BARC, namely, Nuclear Research Laboratory, Srinagar; High Altitude Research Laboratory, Gulmarg; and Variable Energy Cyclotron Centre, Calcutta. BARC is also engaged in basic an applied research in frontier areas of science such as plasma and fusion physics, accelerators and lasers, high temperature superconductivity, condensed matter physics, high pressure physics, high resolution spectroscopy, chemical reaction dynamics and laser induced chemistry, electronics and robotics: radiation biology, and genetic engineering. Report is illustrated with a number of figures, graphs, and coloured pictures. (M.G.B.) figs., refs

  16. CMS tracker slides into centre stage

    CERN Multimedia

    2006-01-01

    As preparations for the magnet test and cosmic challenge get underway, a prototype tracker has been carefully inserted into the centre of CMS. The tracker, in its special platform, is slowly inserted into the centre of CMS. The CMS prototype tracker to be used for the magnet test and cosmic challenge coming up this summer has the same dimensions -2.5 m in diameter and 6 m in length- as the real one and tooling exactly like it. However, the support tube is only about 1% equipped, with 2 m2 of silicon detectors installed out of the total 200 m2. This is already more than any LEP experiment ever used and indicates the great care needed to be taken by engineers and technicians as these fragile detectors were installed and transported to Point 5. Sixteen thousand silicon detectors with a total of about 10 million strips will make up the full tracker. So far, 140 modules with about 100 000 strips have been implanted into the prototype tracker. These silicon strips will provide precision tracking for cosmic muon...

  17. Pharmacist involvement in a diabetic education centre.

    Science.gov (United States)

    Kanitz, J; Birken, B; Ward, V

    1982-01-01

    During the past two years, a multi-discipline health team has been meeting with selected diabetic "problem" patients on a regular basis at the North York General Hospital (NYGH). The patients are referred to the programme by their physicians when they appear to be having difficulty handling or coping with their diabetes. The participants in the programme attend the Diabetic Education Centre (DEC) for one week as day patients in the hospital and are exposed to various types of counselling from members of the Diabetic Education Centre Team (DECT), one of which is the pharmacist. Follow-up from this week of intensive education is made at annual intervals. The main purpose of the pharmacist in the clinic is to provide information for the patients regarding their prescriptions and over the counter (OTC) medication. This is achieved by means of individual patient interviews and informal group discussions, as well as rounds with other team members and contact with patients' families. This programme provides a forum for the patient and the patient's family to obtain valid information about diabetes, as well as problems associated with the disease, and aids in coping with these problems. The team concept enables the patient to be analyzed by all disciplines in order to assess his teaching needs and fulfill them. The pharmacist is continually involved in this information system and plays a valuable role on the team. PMID:10257341

  18. WISB: Warwick Integrative Synthetic Biology Centre.

    Science.gov (United States)

    McCarthy, John

    2016-06-15

    Synthetic biology promises to create high-impact solutions to challenges in the areas of biotechnology, human/animal health, the environment, energy, materials and food security. Equally, synthetic biologists create tools and strategies that have the potential to help us answer important fundamental questions in biology. Warwick Integrative Synthetic Biology (WISB) pursues both of these mutually complementary 'build to apply' and 'build to understand' approaches. This is reflected in our research structure, in which a core theme on predictive biosystems engineering develops underpinning understanding as well as next-generation experimental/theoretical tools, and these are then incorporated into three applied themes in which we engineer biosynthetic pathways, microbial communities and microbial effector systems in plants. WISB takes a comprehensive approach to training, education and outreach. For example, WISB is a partner in the EPSRC/BBSRC-funded U.K. Doctoral Training Centre in synthetic biology, we have developed a new undergraduate module in the subject, and we have established five WISB Research Career Development Fellowships to support young group leaders. Research in Ethical, Legal and Societal Aspects (ELSA) of synthetic biology is embedded in our centre activities. WISB has been highly proactive in building an international research and training network that includes partners in Barcelona, Boston, Copenhagen, Madrid, Marburg, São Paulo, Tartu and Valencia.

  19. WISB: Warwick Integrative Synthetic Biology Centre.

    Science.gov (United States)

    McCarthy, John

    2016-06-15

    Synthetic biology promises to create high-impact solutions to challenges in the areas of biotechnology, human/animal health, the environment, energy, materials and food security. Equally, synthetic biologists create tools and strategies that have the potential to help us answer important fundamental questions in biology. Warwick Integrative Synthetic Biology (WISB) pursues both of these mutually complementary 'build to apply' and 'build to understand' approaches. This is reflected in our research structure, in which a core theme on predictive biosystems engineering develops underpinning understanding as well as next-generation experimental/theoretical tools, and these are then incorporated into three applied themes in which we engineer biosynthetic pathways, microbial communities and microbial effector systems in plants. WISB takes a comprehensive approach to training, education and outreach. For example, WISB is a partner in the EPSRC/BBSRC-funded U.K. Doctoral Training Centre in synthetic biology, we have developed a new undergraduate module in the subject, and we have established five WISB Research Career Development Fellowships to support young group leaders. Research in Ethical, Legal and Societal Aspects (ELSA) of synthetic biology is embedded in our centre activities. WISB has been highly proactive in building an international research and training network that includes partners in Barcelona, Boston, Copenhagen, Madrid, Marburg, São Paulo, Tartu and Valencia. PMID:27284024

  20. Inhomogeneous charging and screening effects in semiconductor quantum dot arrays

    Energy Technology Data Exchange (ETDEWEB)

    Wetzler, R [Institut fuer Theoretische Physik, Technische Universitaet Berlin, Hardenbergstr. 36, 10623 Berlin (Germany); Kunert, R [Institut fuer Theoretische Physik, Technische Universitaet Berlin, Hardenbergstr. 36, 10623 Berlin (Germany); Wacker, A [Fysiska Institutionen, Lunds Universitet, Box 118, 22100 Lund (Sweden); Schoell, E [Institut fuer Theoretische Physik, Technische Universitaet Berlin, Hardenbergstr. 36, 10623 Berlin (Germany)

    2004-07-01

    The electronic properties of quantum dot (QD) arrays are strongly influenced by the Coulomb interaction of electrons within the dot as well as with those in neighbouring dots. In this paper, we investigate this behaviour taking into account screening by a free electron gas in the vicinity of the QDs. We find pronounced effects for standard capacitance[ndash]voltage (CV) measurements of QD structures embedded in a pn-diode. In particular, we show that the three-dimensional nature of the problem is crucial for devices with low dot-density, whereas the self-consistency between electron depletion in the bulk layer and dot occupation is important for high dot-densities. The Coulomb interaction between the dots induces a broadening of the peaks in the CV characteristic which is comparable with the effect of disordered QD arrays, where we considered realistic size and position fluctuations obtained by a kinetic Monte Carlo simulation.

  1. Quantum dot-sized organic fluorescent dots for long-term cell tracing

    Science.gov (United States)

    Li, Kai; Tang, Ben Zhong; Liu, Bin

    2014-03-01

    Fluorescence techniques have been extensively employed to develop non-invasive methodologies for tracking and understanding complex biological processes both in vitro and in vivo, which is of high importance in modern life science research. Among a variety of fluorescent probes, inorganic semiconductor quantum dots (QDs) have shown advantages in terms of better photostability, larger Stokes shift and more feasible surface functionalization. However, their intrinsic toxic heavy metal components and unstable fluorescence at low pH greatly impede the applications of QDs in in vivo studies. In this work, we developed novel fluorescent probes that can outperform currently available QD based probes in practice. Using conjugated oligomer with aggregation-induced emission characteristics as the fluorescent domain and biocompatible lipid-PEG derivatives as the encapsulation matrix, the obtained organic dots have shown higher brightness, better stability in biological medium and comparable size and photostability as compared to their counterparts of inorganic QDs. More importantly, unlike QD-based probes, the organic fluorescent dots do not blink, and also do not contain heavy metal ions that could be potentially toxic when applied for living biosubstrates. Upon surface functionalization with a cell-penetrating peptide, the organic dots greatly outperform inorganic quantum dots in both in vitro and in vivo long-term cell tracing studies, which will be beneficial to answer crucial questions in stem cell/immune cell therapies. Considering the customized fluorescent properties and surface functionalities of the organic dots, a series of biocompatible organic dots will be developed to serve as a promising platform for multifarious bioimaging tasks in future.

  2. Children's Centre "3 in 1 - together"

    Science.gov (United States)

    Gancheva, Hristina

    2013-04-01

    "There are only two ways to life your live. One is as though nothing is a miracle. The other is as though everything is a miracle." Albert Einstein Children's Centre "3 in 1" is an extracurricular unit linked to the High School of Zlatartitsa, St. Cyril and St. Methodius, accomplished with the help of the municipality and many volunteers from the local community. With its activity it forms in children patriotic spirit, love for nature, active citizenship, and an impulse for a healthy life through communication with nature, saving the traditions and history, insurance of equality of the kids of the local five ethnicities and participation in activities in the sphere of science, art, sport and tourism. The educational work is mainly directed towards kids with difficulties with communication, hyperactivity, aggression, problems in their families, or those deprived of parental care. For a few years in the Children's Centre there have been clubs of interests: "Gardeners" - kids cultivate a garden. They plow, dig, plant, put in, irrigate and weed under the watch of Ms Stafka Nikolova, parents, and volunteers of the local community. The ecologically clean products - vegetables and fruits, kids use to cook delicious meals, sell, or give away. Weeds are also utilized; they are making herbarium out of them. "Cooks" - "What to have for lunch, when mom is out?". One can learn a lot of wonderful recipes from the club "Cooks". Products are own made, raised with love. In 2010, on the on the annual traditional holiday of the garden soup in Zlataritsa, the little cooks won third prize for making a delicious vegetable soup. On the same day, the 26 years old Nadezhda Savova, Cultural and Social Anthropology PhD in Princeton, founded the second community bakery in Bulgaria in Children's Centre "3 in1". Nadezhda Savova was declared traveler of 2012 by National Geographic. After the baking house in Gabrovo and Zlataritsa, Nadezhda also founded such projects in Sofia, Varna and Ruse

  3. Project for a renewable energy research centre

    Directory of Open Access Journals (Sweden)

    Andrea Giachetta

    2011-04-01

    Full Text Available In Liguria, where sustainable approaches to the design, construction and management of buildings enjoy scant currency, the idea of a company from Milan (FERA s.r.l. setting up a research centre for studies into renewable energy resources, could well open up very interesting development opportunities.The project includes: environmental rehabilitation (restoration projects; strategies for the protection of water resources and waste management systems; passive and active solar systems (solar thermal and experiments with thermodynamic solar energy; hyperinsulation systems, passive cooling of buildings; use of natural materials; bio-climatic use of vegetation. The author describes the project content within the context of the multidisciplinary work that has gone into it.

  4. Annual report 1992 - Austrian Research Centre Seibersdorf

    International Nuclear Information System (INIS)

    This is a non-technical progress report (in English) of the activities of the Research Centre Seibersdorf in the fields of energy and safety, materials research, isotope and radiation techniques, environment protection, health and food and industrial consulting. Within other non nuclear related highlights the newly built radio-pharmaceutical laboratory is described, which will guarantee the reliable supply of products and develop new diagnostic and therapeutic preparations. A newly developed whole-body counter for measuring internal radiation is in use in the Vienna General Hospital to obtain better information of the patient's metabolism and can thus assess the efficiency of pharmaceuticals. The research in the field of toxicology and carcinogenicity was intensified. Geological dating was performed for the 'Continental Deep-Drilling Programme' on behalf of the Max Planck Institute. Environmental data acquisition was mainly conducted in the field of ozone, water quality, air pollution and electro-smog (quittner, rieger)

  5. Stimulated emission from NV centres in diamond

    CERN Document Server

    Jeske, Jan; McGuinness, Liam P; Reineck, Philip; Johnson, Brett C; McCallum, Jeffrey C; Jelezko, Fedor; Volz, Thomas; Cole, Jared H; Gibson, Brant C; Greentree, Andrew D

    2016-01-01

    Stimulated emission is the process fundamental to laser operation, thereby producing coherent photon output. Despite negatively-charged nitrogen-vacancy (NV$^-$) centres being discussed as a potential laser medium since the 1980's, there have been no definitive observations of stimulated emission from ensembles of NV$^-$ to date. Reasons for this lack of demonstration include the short excited state lifetime and the occurrence of photo-ionisation to the neutral charge state by light around the zero-phonon line. Here we show both theoretical and experimental evidence for stimulated emission from NV$^-$ states using light in the phonon-sidebands. Our system uses a continuous wave pump laser at 532 nm and a pulsed stimulating laser that is swept across the phononic sidebands of the NV$^-$. Optimal stimulated emission is demonstrated in the vicinity of the three-phonon line at 700 nm. Furthermore, we show the transition from stimulated emission to photoionisation as the stimulating laser wavelength is reduced fro...

  6. MATERNAL MORTALITY IN A TERTIARY CARE CENTRE

    Directory of Open Access Journals (Sweden)

    Harpreet

    2013-06-01

    Full Text Available ABSTRACT: Maternal Mortality in A Tertiary Care Centre. OBJECTIVE: To study maternal mortality and the complications leading to maternal death. METHODS: A retrospective study of hospital record to study maternal mortality and its causes over 3 years from January 2010 to December 2012. RESULTS: There were a total of 58 maternal deaths out of 2823 live births giving a maternal mortality ratio of 2054.55 per one lakh live births. Unbooked and late referrals account for 77.58% of maternal deaths. The majority of deaths around 75.86% were in 20-30 years age group. Haemorrhage was the commonest causes of death (24.12% followed by sepsis (18.96% and pregnancy induced hypertension 15.51% Anemia contributed to the most common indirect cause of maternal morality. CONCLUSION: Haemorrhage, sepsis and pregnancy induced hypertension including eclampsia were the direct major causes of death. Anaemia and cardiac diseases were other indirect causes of death.

  7. Data communication at the CERN computer centre

    CERN Document Server

    Bruins, T; Pieters, R; Slettenhaar, Hendrik J; Van de Kerk, P

    1972-01-01

    The growing interest for on-line computer service and process control at CERN decentralises certain computer activities. Small process computers, remote batch stations and user terminals are to be backed by a powerful central computer. The present data network is principally star shaped. At the centre of it is a CDC 6600-6500 computer combination. It has a front end CDC 3100 computer with a Hewlett Packard 2116 as multiplexer. Some details about the fast parallel connections between the CDC 3100 and the HP 2116B are given in the paper, as well as descriptions of some computer simulation techniques used to test the present systems. Finally some plans on a future network are given. (12 refs).

  8. Surviving stroke in an Ebola Treatment Centre.

    Science.gov (United States)

    Dhillon, Paul; McCarthy, Sinead; Gibbs, Michael

    2015-01-01

    A middle aged woman presented to an Ebola Treatment Centre in West Africa with a 4-day history of fever, fatigue, joint pain and vomiting. She tested positive for Ebola virus disease (EVD) and a standard treatment platform of care was started. On day 3 of her admission, she was found to have suffered a left-sided CVA of unknown aetiology. Treatment was largely supportive within a resource-constrained environment and the added layer of providing care with extensive personal protective equipment, and human resource and safety constraints. The patient was able to clear the EVD and did regain some functional use of her arm and leg. She was discharged on day 15 of her stay, as a survivor of both stroke and Ebola. PMID:26516244

  9. Bhabha Atomic Research Centre : annual report 1990

    International Nuclear Information System (INIS)

    Research and development (R and D) activities of the Bhabha Atomic Research Centre (BARC) carried out during 1990 are reported. The main thrust of the R and D activities of BARC is on : (1)providing support to the nuclear power programme, (2)designing, building and utilising research reactors, (3)working in related frontline technologies, and also (4)basic research in frontier areas of science. These activities are described in brief under the chapters entitled : (1)Physical Sciences (2)Chemical Sciences (3)Materials and Material Science (4)Radioisotopes (5)Reactions (6)Fuel Cycle (7)Radiological Safety and Protection (8)Electronics and Instrumentation (9)Engineering Services (10)Life Sciences and (11)General. At the end of each chapter a list of papers and reports published in the subject field indicated by the title of the chapter is given. (N.B.). figs., tabs

  10. Beef quality assessed at European research centres.

    Science.gov (United States)

    Dransfield, E; Nute, G R; Roberts, T A; Boccard, R; Touraille, C; Buchter, L; Casteels, M; Cosentino, E; Hood, D E; Joseph, R L; Schon, I; Paardekooper, E J

    1984-01-01

    Loin steaks and cubes of M. semimembranosus from eight (12 month old) Galloway steers and eight (16-18 month old) Charolais cross steers raised in England and from which the meat was conditioned for 2 or 10 days, were assessed in research centres in Belgium, Denmark, England, France, the Federal Republic of Germany, Ireland, Italy and the Netherlands. Laboratory panels assessed meat by grilling the steaks and cooking the cubes in casseroles according to local custom using scales developed locally and by scales used frequently at other research centres. The meat was mostly of good quality but with sufficient variation to obtain meaningful comparisons. Tenderness and juiciness were assessed most, and flavour least, consistently. Over the 32 meats, acceptability of steaks and casseroles was in general compounded from tenderness, juiciness and flavour. However, when the meat was tough, it dominated the overall judgement; but when tender, flavour played an important rôle. Irish and English panels tended to weight more on flavour and Italian panels on tenderness and juiciness. Juciness and tenderness were well correlated among all panels except in Italy and Germany. With flavour, however, Belgian, Irish, German and Dutch panels ranked the meats similarly and formed a group distinct from the others which did not. The panels showed a similar grouping for judgements of acceptability. French and Belgian panels judged the steaks from the older Charolais cross steers to have more flavour and be more juicy than average and tended to prefer them. Casseroles from younger steers were invariably preferred although the French and Belgian panels judged aged meat from older animals equally acceptable. These regional biases were thought to be derived mainly from differences in cooking, but variations in experience and perception of assessors also contributed. PMID:22055992

  11. Hadron production in nuclear collisions from the NA49 experiment at 158GeV/c centre dot A

    CERN Document Server

    Siklér, F; Barna, D; Barnby, L S; Bartke, Jerzy; Barton, R A; Betev, L; Bialkowska, H; Billmeier, A; Blume, C; Blyth, C O; Boimska, B; Bracinik, J; Brady, F P; Brun, R; Buncic, P; Carr, L; Cebra, D; Cooper, G E; Cramer, J G; Csató, P; Eckardt, V; Eckhardt, F; Ferenc, D; Fischer, H G; Fodor, Z; Foka, P; Freund, P; Friese, V; Ftácnik, J; Gál, J; Ganz, R E; Gazdzicki, M; Gladysz-Dziadus, E; Grebieszkow, J; Harris, J W; Hegyi, S; Hlinka, V; Höhne, C; Igo, G; Ivanov, M; Jacobs, P; Janik, R; Jones, P G; Kadija, K; Kolesnikov, V I; Kowalski, M; Lasiuk, B; Lednicky, R; Lévai, Peter; Malakhov, A I; Margetis, S; Markert, C; Mayes, B W; Melkumov, G L; Molnár, J; Nelson, J M; Odyniec, Grazyna Janina; Oldenburg, M; Pálla, G; Panagiotou, A D; Petridis, A; Pikna, M; Pinsky, L; Poskanzer, A M; Prindle, D J; Pühlhofer, F; Reid, J G; Renfordt, R E; Retyk, W; Ritter, H G; Röhrich, D; Roland, C; Roland, G; Rybicki, A; Sammer, T; Sandoval, A; Sann, H; Semenov, A Yu; Schäfer, E; Schmitz, N; Seyboth, P; Sitár, B; Skrzypczak, E; Snellings, R; Squier, G T A; Stock, R; Strmen, P; Ströbele, H; Susa, T; Szarka, I; Szentpétery, I; Sziklai, J; Toy, M; Trainor, T A; Trentalange, S; Ullrich, T; Varga, D; Vassiliou, Maria; Veres, G I; Vesztergombi, G; Voloshin, S A; Vranic, D; Wang, F; Weerasundara, D D; Wenig, S; Whitten, C; Xu, N; Yates, T A; Yoo, I K; Zimányi, J

    1999-01-01

    With its large acceptance and particle identification coverage the NA49 experiment (Fig. 1) can study hadron production in a wide range of high energy reactions [1]. Originally aimed at examining central Pb+Pb collisions for signatures of quark-gluon plasma formation, the scope of the experiment has been enhanced with a systematic study of impact parameter and projectile size dependence, as well as the inclusion of the more elementary p+p and p+A interactions. The question is: are predicted signals of the quark-gluon plasma observed and are there discontinuities which would support the concept of hadronic phase transition?

  12. Collaborating at a distance: operations centres, tools, and trends

    Energy Technology Data Exchange (ETDEWEB)

    Gottschalk, Erik E.; /Fermilab

    2009-05-01

    Successful operation of the LHC and its experiments is crucial to the future of the worldwide high-energy physics program. Remote operations and monitoring centres have been established for the CMS experiment in several locations around the world. The development of remote centres began with the LHC{at}FNAL ROC and has evolved into a unified approach with distributed centres that are collectively referred to as 'CMS Centres Worldwide'. An overview of the development of remote centres for CMS will be presented, along with a synopsis of collaborative tools that are used in these centres today and trends in the development of remote operations capabilities for high-energy physics.

  13. International Centre for Theoretical Physics, Trieste Scientific activities in 1991

    International Nuclear Information System (INIS)

    The document contains three parts. Part 1 is a general review of the scientific activities of the Centre in 1991, including a statistical digest. Part II presents the scientific programme of the Centre in the following fields: Fundamental Physics, Condensed Matter Physics, Mathematics, Physics and Energy, Physics and Environment, Applied Physics, Adriatico Research Conferences, as well as other aspects of the Centre activities in 1991. Part III lists the publications issued in 1991. Tabs

  14. Routing algorithms for recursively-defined data centre networks.

    OpenAIRE

    Erickson, A.; Kiasari, A.; Navaridas, J.; Stewart, I.A.

    2015-01-01

    The server-centric data centre network architecture can accommodate a wide variety of network topologies. Newly proposed topologies in this arena often require several rounds of analysis and experimentation in order that they might achieve their full potential as data centre networks. We propose a family of novel routing algorithms on two well-known data centre networks of this type, (Generalized) DCell and FiConn, using techniques that can be applied more generally to the class of networks w...

  15. Complex Modelling Scheme Of An Additive Manufacturing Centre

    Science.gov (United States)

    Popescu, Liliana Georgeta

    2015-09-01

    This paper presents a modelling scheme sustaining the development of an additive manufacturing research centre model and its processes. This modelling is performed using IDEF0, the resulting model process representing the basic processes required in developing such a centre in any university. While the activities presented in this study are those recommended in general, changes may occur in specific existing situations in a research centre.

  16. International Centre for Theoretical Physics, Trieste. Scientific activities in 1990

    International Nuclear Information System (INIS)

    The document contains three parts: Part I is a general review of the scientific activities of the Centre in 1990, including a statistical digest. Part II describes the scientific programme of the Centre in the following fields: Fundamental physics, condensed nuclear physics, mathematics, physics and energy, physics and environment, physics of the living state, applied physics Adriatico research conferences and other aspects of the Centre activities. Part III lists the publications issued in 1990

  17. Bright infrared quantum-dot light-emitting diodes through inter-dot spacing control

    KAUST Repository

    Sun, Liangfeng

    2012-05-06

    Infrared light-emitting diodes are currently fabricated from direct-gap semiconductors using epitaxy, which makes them expensive and difficult to integrate with other materials. Light-emitting diodes based on colloidal semiconductor quantum dots, on the other hand, can be solution-processed at low cost, and can be directly integrated with silicon. However, so far, exciton dissociation and recombination have not been well controlled in these devices, and this has limited their performance. Here, by tuning the distance between adjacent PbS quantum dots, we fabricate thin-film quantum-dot light-emitting diodes that operate at infrared wavelengths with radiances (6.4 W sr \\'1 m \\'2) eight times higher and external quantum efficiencies (2.0%) two times higher than the highest values previously reported. The distance between adjacent dots is tuned over a range of 1.3 nm by varying the lengths of the linker molecules from three to eight CH 2 groups, which allows us to achieve the optimum balance between charge injection and radiative exciton recombination. The electroluminescent powers of the best devices are comparable to those produced by commercial InGaAsP light-emitting diodes. By varying the size of the quantum dots, we can tune the emission wavelengths between 800 and 1,850 nm.© 2012 Macmillan Publishers Limited.

  18. Interference effects in a double quantum dot system with inter-dot Coulomb correlations

    International Nuclear Information System (INIS)

    Electron transport through a double quantum dot system is studied with the use of the Green function formalism based on the equation of motion method, and an interplay between interference and Coulomb blockade effects due to inter-dot correlations is discussed. A double structure with two Fano resonances (or antiresonances) is found in the conductance spectrum. Fano features are weakly influenced by the presence of Coulomb interaction but the conductance is strongly suppressed in the energy region with the Fermi level in the leads close to the aligned levels of both dots. This Coulomb blockade effect takes place when the coupling between the dots is of repulsive character. On the other hand, the conductance of an artificial molecule with attractive inter-dot coupling is only slightly modified in this energy region. As a sign of the coupling can be easily changed in a presence of an external magnetic field by changes of the magnetic flux there is the possibility to control variations of the conductance, which may be important from the application point of view

  19. Ordinance on the Finnish Centre of Radiation and Nuclear Safety

    International Nuclear Information System (INIS)

    This Ordinance was adopted in implementation of the 1983 Act setting up the Finnish Centre for Radiation and Nuclear Safety and the 1987 Nuclear Energy Act and entered into force on 1 November 1990. The Ordinance specifies the tasks of the Centre, as provided under both Acts, and gives it several supplementary responsibilities. In addition to its overall competence in respect of radiation safety, the Centre will carry out research into and supervise the health effects of radiation and maintain a laboratory for national measurements in that field. The Ordinance also sets out the Centre's organisation chart and the staff duties

  20. Crystalline roof glazing - Westside shopping centre, Berne; Kristalline Dachverglasungen

    Energy Technology Data Exchange (ETDEWEB)

    Enkerli, W.

    2009-07-01

    This illustrated article takes a look at the new shopping and leisure centre on the western outskirts of Berne, Switzerland. In particular, the roof of this unusual building over the motorway with its sloping walls and zig-zag design is looked at. The centre's shopping mall, adventure baths and spa, a multiplex cinema, an old peoples' home and a hotel are briefly discussed, as is the embedding of the centre in its suburban environment. The roof construction with its crystalline skylights is examined and discussed in detail. The centre's building technical services are also briefly commented on.

  1. Entangling distant quantum dots using classical interference

    Science.gov (United States)

    Busch, Jonathan; Kyoseva, Elica S.; Trupke, Michael; Beige, Almut

    2008-10-01

    We show that it is possible to employ reservoir engineering to turn two distant and relatively bad cavities into one good cavity with a tunable spontaneous decay rate. As a result, quantum computing schemes, which would otherwise require the shuttling of atomic qubits in and out of an optical resonator, can now be applied to distant quantum dots. To illustrate this we transform a recent proposal to entangle two qubits via the observation of macroscopic fluorescence signals [J. Metz , Phys. Rev. Lett. 97, 040503 (2006)] to the electron-spin states of two semiconductor quantum dots. Our scheme requires neither the coherent control of qubit-qubit interactions nor the detection of single photons. Moreover, the scheme is relatively robust against spin-bath couplings, parameter fluctuations, and the spontaneous emission of photons.

  2. Mesoscopic Cavity Quantum Electrodynamics with Quantum Dots

    CERN Document Server

    Childress, L I; Lukin, M D

    2003-01-01

    We describe an electrodynamic mechanism for coherent, quantum mechanical coupling between spacially separated quantum dots on a microchip. The technique is based on capacitive interactions between the electron charge and a superconducting transmission line resonator, and is closely related to atomic cavity quantum electrodynamics. We investigate several potential applications of this technique which have varying degrees of complexity. In particular, we demonstrate that this mechanism allows design and investigation of an on-chip double-dot microscopic maser. Moreover, the interaction may be extended to couple spatially separated electron spin states while only virtually populating fast-decaying superpositions of charge states. This represents an effective, controllable long-range interaction, which may facilitate implementation of quantum information processing with electron spin qubits and potentially allow coupling to other quantum systems such as atomic or superconducting qubits.

  3. Many electron effects in semiconductor quantum dots

    Indian Academy of Sciences (India)

    R K Pandey; Manoj K Harbola; V Ranjan; Vijay A Singh

    2003-01-01

    Semiconductor quantum dots (QDs) exhibit shell structures, very similar to atoms. Termed as ‘artificial atoms’ by some, they are much larger (1 100 nm) than real atoms. One can study a variety of manyelectron effects in them, which are otherwise difficult to observe in a real atom. We have treated these effects within the local density approximation (LDA) and the Harbola–Sahni (HS) scheme. HS is free of the selfinteraction error of the LDA. Our calculations have been performed in a three-dimensional quantum dot. We have carried out a study of the size and shape dependence of the level spacing. Scaling laws for the Hubbard ‘’ are established.

  4. Magnetoconductance fluctuations in open bismuth quantum dots

    Science.gov (United States)

    Hackens, B.; Minet, J. P.; Farhi, G.; Crahay, A.; Faniel, S.; Gustin, C.; Bayot, V.

    2002-03-01

    We investigate the low temperature (300 mK - 10 K) magnetoconductance of open circular bismuth quantum dots (diameter: 500 nm). The structures are fabricated using a combination of electron beam lithography, lift off and plasma etching techniques on bismuth thin films evaporated on heated SiO2 substrates. We observe reproducible magnetoconductance fluctuations (UCFs) up to 5T, qualitatively similar to conductance fluctuations evidenced in open quantum dots patterned in high mobility semiconductor heterostructures. In our samples, UCFs are superposed on a slowly varying negative magnetoconductance background. We also observe a sharp conductance maximum centered in B=0, which is reminescent of the spin-orbit induced anti-localisation phenomenon. The behavior of UCFs and of the conductance maximum is discussed as a function of the temperature, thickness and degree of cristallinity of the cavity.

  5. Barrier Li Quantum Dots in Magnetic Fields

    Institute of Scientific and Technical Information of China (English)

    LIU Yi-Min; LI Xiao-Zhu; YAN Wen-Hong; BAO Cheng-Guang

    2003-01-01

    The methods for the few-body system are introduced to investigate the states of the barrier Li quantumdots (QDs) in an arbitrary strength of magnetic field. The configuration, which consists of a positive ion located on thez-axis at a distance d from the two-dimensional QD plane (the x-y plane) and three electrons in the dot plane boundby the positive ion, is called a barrier Li center. The system, which consists of three electrons in the dot plane bound bythe ion, is called a barrier Li QD. The dependence of energy of the state of the barrier Li QD on an external magneticfield B and the distance d is obtained. The angular momentum L of the ground states is found to jump not only withthe variation of B but also with d.

  6. Protease-activated quantum dot probes

    Science.gov (United States)

    Chang, Emmanuel; Sun, Jiantang; Miller, Jordan S.; Yu, William W.; Colvin, Vicki L.; West, Jennifer L.; Drezek, Rebekah

    2006-04-01

    We demonstrate a novel quantum dot based probe with inherent signal amplification upon interaction with a targeted proteolytic enzyme. This probe may be useful for imaging in cancer detection and diagnosis. In this system, quantum dots (QDs) are bound to gold nanoparticles (AuNPs) via a proteolytically-degradable peptide sequence to non-radiatively suppress luminescence. A 71% reduction in luminescence was achieved with conjugation of AuNPs to QDs. Peptide cleavage results in release of AuNPs and restores radiative QD photoluminescence. Initial studies observed a 52% rise in luminescence over 47 hours of exposure to 0.2 mg/mL collagenase. These probes can be customized for targeted degradation simply by changing the sequence of the peptide linker.

  7. Facile labeling of lipoglycans with quantum dots

    International Nuclear Information System (INIS)

    Bacterial endotoxins or lipopolysaccharides (LPS) are among the most potent activators of the innate immune system, yet mechanisms of their action and in particular the role of glycans remain elusive. Efficient non-invasive labeling strategies are necessary for studying interactions of LPS glycans with biological systems. Here we report a new method for labeling LPS and other lipoglycans with luminescent quantum dots. The labeling is achieved by partitioning of hydrophobic quantum dots into the core of various LPS aggregates without disturbing the native LPS structure. The biofunctionality of the LPS-Qdot conjugates is demonstrated by the labeling of mouse monocytes. This simple method should find broad applicability in studies concerned with visualization of LPS biodistribution and identification of LPS binding agents.

  8. Efficient Luminescence from Perovskite Quantum Dot Solids

    KAUST Repository

    Kim, Younghoon

    2015-11-18

    © 2015 American Chemical Society. Nanocrystals of CsPbX3 perovskites are promising materials for light-emitting optoelectronics because of their colloidal stability, optically tunable bandgap, bright photoluminescence, and excellent photoluminescence quantum yield. Despite their promise, nanocrystal-only films of CsPbX3 perovskites have not yet been fabricated; instead, highly insulating polymers have been relied upon to compensate for nanocrystals\\' unstable surfaces. We develop solution chemistry that enables single-step casting of perovskite nanocrystal films and overcomes problems in both perovskite quantum dot purification and film fabrication. Centrifugally cast films retain bright photoluminescence and achieve dense and homogeneous morphologies. The new materials offer a platform for optoelectronic applications of perovskite quantum dot solids.

  9. Light emission from Si quantum dots

    Directory of Open Access Journals (Sweden)

    Philippe M. Fauchet

    2005-01-01

    Full Text Available Si quantum dots (QDs as small as ∼2 nm in diameter have been synthesized by a variety of techniques. Because of quantum confinement and the elimination of bulk or surface defects, these dots can emit light from the near infrared throughout the visible with quantum efficiencies in excess of 10%. The luminescence wavelength range has been extended to longer wavelengths by the addition of light-emitting rare earths such as erbium (Er. Light-emitting devices (LEDs have been fabricated and their performances are starting to approach those of direct band gap semiconductor or organic LEDs. A search for a Si QD-based laser is even under way. The state-of-the-art in the materials science, physics, and device development of luminescent Si QDs is reviewed and areas of future research are pointed out.

  10. An addressable quantum dot qubit with fault-tolerant control-fidelity.

    Science.gov (United States)

    Veldhorst, M; Hwang, J C C; Yang, C H; Leenstra, A W; de Ronde, B; Dehollain, J P; Muhonen, J T; Hudson, F E; Itoh, K M; Morello, A; Dzurak, A S

    2014-12-01

    Exciting progress towards spin-based quantum computing has recently been made with qubits realized using nitrogen-vacancy centres in diamond and phosphorus atoms in silicon. For example, long coherence times were made possible by the presence of spin-free isotopes of carbon and silicon. However, despite promising single-atom nanotechnologies, there remain substantial challenges in coupling such qubits and addressing them individually. Conversely, lithographically defined quantum dots have an exchange coupling that can be precisely engineered, but strong coupling to noise has severely limited their dephasing times and control fidelities. Here, we combine the best aspects of both spin qubit schemes and demonstrate a gate-addressable quantum dot qubit in isotopically engineered silicon with a control fidelity of 99.6%, obtained via Clifford-based randomized benchmarking and consistent with that required for fault-tolerant quantum computing. This qubit has dephasing time T2* = 120 μs and coherence time T2 = 28 ms, both orders of magnitude larger than in other types of semiconductor qubit. By gate-voltage-tuning the electron g*-factor we can Stark shift the electron spin resonance frequency by more than 3,000 times the 2.4 kHz electron spin resonance linewidth, providing a direct route to large-scale arrays of addressable high-fidelity qubits that are compatible with existing manufacturing technologies. PMID:25305743

  11. Status of Growth Monitoring in Anganwadi Centres of a Primary Health Centre, Thirubhuvanai, Puducherry

    Directory of Open Access Journals (Sweden)

    Gurukartick J

    2013-08-01

    Full Text Available Purpose: To assess the status of growth monitoring activities and difficulties faced by anganwadi workers (AWWs at the anganwadi centres (AWCs. Methodology: A survey was conducted among AWWs under a rural Primary Health Centre. Structured observations on weight measurement were made using a check list. Secondary data on record keeping and maintenance was collected. Findings: Study participants (n=20 had a 24 (± 10.25 years of experience in Integrated Child Development Services and underwent training once in two years. For advising mothers of malnourished children, deworming and immunization was not mentioned by majority AWWs. In AWCs, children less than 6 month were weighed on bathroom scale and not by Salter’s scale. Unclothing the child before weighing was practiced by only 10% AWWs. Nonfunctional weighing machine was the major problem reported by AWWs. Conclusion: There were gaps in the growth monitoring activities in AWCs of a PHC, Thirubhuvanai which needs to be tackled.

  12. The role of the Czechoslovak Nuclear Information Centre as a reference centre

    International Nuclear Information System (INIS)

    The Nuclear Information Centre (NIC) is the sector information centre for the Czechoslovak nuclear programme which comprises the peaceful uses of nuclear energy, ionizing radiation and isotopes. Briefly characterized are the different types of services provided which include search processing, librarian services, study analytical work, publishing activity, the sector inventory of research reports, searches, trip reports and translations and of late the provision of factual data. In this respect this includes the following systems: Economics of Nuclear Power Plants, and Nuclear Power Plant Indicators. The NIC also processes computer-based analyses of selected topics from a document retrieval base. For these analyses the use of the COMMODORE personal computer and foreign firm software is being envisaged. In the first stage the analyses will be made from the INIS data base. (Z.M.)

  13. Ratiometric Temperature Sensing with Semiconducting Polymer Dots

    OpenAIRE

    Ye, Fangmao; Wu, Changfeng; Jin, Yuhui; Chan, Yang-Hsiang; Zhang, Xuanjun; Chiu, Daniel T.

    2011-01-01

    This communication describes ultra-bright single-nanoparticle ratiometric temperature sensors based on semiconducting polymer dots (Pdots). We attached the temperature sensitive dye—Rhodamine B (RhB), whose emission intensity decreases with increasing temperature—within the matrix of Pdots. The as-prepared Pdot-RhB nanoparticle showed excellent temperature sensitivity and high brightness because it took advantage of the light harvesting and amplified energy transfer capability of Pdots. More ...

  14. The Silicon:Colloidal Quantum Dot Heterojunction

    KAUST Repository

    Masala, Silvia

    2015-10-13

    A heterojunction between crystalline silicon and colloidal quantum dots (CQDs) is realized. A special interface modification is developed to overcome an inherent energetic band mismatch between the two semiconductors, and realize the efficient collection of infrared photocarriers generated in the CQD film. This junction is used to produce a sensitive near infrared photodetector. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  15. Adiabatic description of nonspherical quantum dot models

    Energy Technology Data Exchange (ETDEWEB)

    Gusev, A. A., E-mail: gooseff@jinr.ru; Chuluunbaatar, O.; Vinitsky, S. I. [Joint Institute for Nuclear Research (Russian Federation); Dvoyan, K. G.; Kazaryan, E. M.; Sarkisyan, H. A. [Russian-Armenian (Slavonic) University (Armenia); Derbov, V. L.; Klombotskaya, A. S.; Serov, V. V. [Saratov State University (Russian Federation)

    2012-10-15

    Within the effective mass approximation an adiabatic description of spheroidal and dumbbell quantum dot models in the regime of strong dimensional quantization is presented using the expansion of the wave function in appropriate sets of single-parameter basis functions. The comparison is given and the peculiarities are considered for spectral and optical characteristics of the models with axially symmetric confining potentials depending on their geometric size, making use of the complete sets of exact and adiabatic quantum numbers in appropriate analytic approximations.

  16. Shot noise of coupled semiconductor quantum dots

    OpenAIRE

    Kiesslich, G.; Wacker, A; Schoell, E.

    2003-01-01

    The low-frequency shot noise properties of two electrostatically coupled semiconductor quantum dot states which are connected to emitter/collector contacts are studied. A master equation approach is used to analyze the bias voltage dependence of the Fano factor as a measure of temporal correlations in tunneling current caused by Pauli's exclusion principle and the Coulomb interaction. In particular, the influence of the Coulomb interaction on the shot noise behavior is discussed in detail and...

  17. SPECTRAL PROPERTIES OF SHUNGITE QUANTUM DOTS

    OpenAIRE

    RAZBIRIN B.S.; ROZHKOVA N.N.; Sheka, E. F.; Nelson, D. K.; Starukhin, A. N.; Goryunov, A. S.

    2014-01-01

    A low-temperature study has been performed for aqueous shungite, carbon tetrachloride, and toluene dispersions. Spectral characteristics for graphene quantum dots (GQDs) of shungite, attributed to individual fragments of reduced graphene oxide (rGO), reveal a dual character of the dispersions emitting centers: individual GQDs are responsible for the spectra position while fractal structure of GQD colloids provides large broadening of the spectra due to structural inhomogeneity of the colloida...

  18. Semiconductor Quantum Dots for Biomedicial Applications

    OpenAIRE

    Lijia Shao; Feng Yan; Yanfang Gao

    2011-01-01

    Semiconductor quantum dots (QDs) are nanometre-scale crystals, which have unique photophysical properties, such as size-dependent optical properties, high fluorescence quantum yields, and excellent stability against photobleaching. These properties enable QDs as the promising optical labels for the biological applications, such as multiplexed analysis of immunocomplexes or DNA hybridization processes, cell sorting and tracing, in vivo imaging and diagnostics in biomedicine. Meanwhile, QDs can...

  19. Quantum dots: synthesis, bioapplications, and toxicity

    OpenAIRE

    Valizadeh, Alireza; Mikaeili, Haleh; Samiei, Mohammad; Farkhani, Samad Mussa; Zarghami, Nosratalah; Kouhi, Mohammad; Akbarzadeh, Abolfazl; Davaran, Soodabeh

    2012-01-01

    This review introduces quantum dots (QDs) and explores their properties, synthesis, applications, delivery systems in biology, and their toxicity. QDs are one of the first nanotechnologies to be integrated with the biological sciences and are widely anticipated to eventually find application in a number of commercial consumer and clinical products. They exhibit unique luminescence characteristics and electronic properties such as wide and continuous absorption spectra, narrow emission spectra...

  20. The pinning effect in quantum dots

    Energy Technology Data Exchange (ETDEWEB)

    Monisha, P. J., E-mail: pjmonisha@gmail.com [School of Physics, University of Hyderabad, Hyderabad-500046 (India); Mukhopadhyay, Soma [Department of Physics, D V R College of Engineering and Technology, Hyderabad-502285 (India)

    2014-04-24

    The pinning effect is studied in a Gaussian quantum dot using the improved Wigner-Brillouin perturbation theory (IWBPT) in the presence of electron-phonon interaction. The electron ground state plus one phonon state is degenerate with the electron in the first excited state. The electron-phonon interaction lifts the degeneracy and the first excited states get pinned to the ground state plus one phonon state as we increase the confinement frequency.

  1. Depleted Bulk Heterojunction Colloidal Quantum Dot Photovoltaics

    KAUST Repository

    Barkhouse, D. Aaron R.

    2011-05-26

    The first solution-processed depleted bulk heterojunction colloidal quantum dot solar cells are presented. The architecture allows for high absorption with full depletion, thereby breaking the photon absorption/carrier extraction compromise inherent in planar devices. A record power conversion of 5.5% under simulated AM 1.5 illumination conditions is reported. Copyright © 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  2. Magnetic field and position effects on the absorption coefficient of a shallow donor in CdSe quantum dot

    International Nuclear Information System (INIS)

    The influence of impurity position, magnetic field and size on the donor binding energy and absorption coefficient associated with transitions between the electron bound to a donor and the first conduction subband have been studied for CdSe quantum dots with infinite potential confinement. We have used a variational procedure within the effective mass approximation. We present results for the absorption coefficient as a function of the photon energy for several field strengths and arbitrary impurity positions. It is found that for all sizes of the dot the absorption peak associated with an on-centre donor impurity is negligible and the most significant contribution comes from a donor located near the edge. The threshold absorption peak is strongly shifted toward high energies when the donor moves from the edge to the center accompanied with an important diminution of the intensity. While for large dot the threshold absorption peak is approximately insensitive to the donor position, we have also found that the application of magnetic field shifts the threshold absorption peak toward high energy and reduces the intensity of absorption coefficient. (author)

  3. The quantum dot nanoconjugate tool box (Invited Paper)

    Science.gov (United States)

    Tomlinson, I. D.; Wright, D. W.; Giorgio, T. D.; Blakely, R. D.; Pennycook, S. J.; Hercules, D.; Bentzen, L.; Smith, R. A.; McBride, J.; Vergne, M. J.; Rosenthal, S.

    2005-04-01

    The surface coating of quantum dots has been characterised using Z-stem. Quantum dots have been pegylated to increase stability in aqueous solution. The fluorescence intensity of the quantum dots was modulated pegylation. PEG was coupled using different ratios of EDC, PEG and NHS. Optimum coupling conditions were found to occur when 2000 equivalents of PEG were reacted with 1 equivalent of dot in the presence of 1500 equivalents of NHS and EDC. Angiotensin II was also conjugated to quantum dots and these conjugates were shown to be biologically active. Quantum dots have also been surface functionalised with other peptides such as NGR with subsequent demonstration of cell surface binding and can be characterized by flow cytometry.

  4. Templated self-assembly of SiGe quantum dots

    Energy Technology Data Exchange (ETDEWEB)

    Dais, Christian

    2009-08-19

    This PhD thesis reports on the fabrication and characterization of exact aligned SiGe quantum dot structures. In general, SiGe quantum dots which nucleate via the Stranski-Krastanov growth mode exhibit broad size dispersion and nucleate randomly on the surface. However, to tap the full potential of SiGe quantum dots it is necessary to control the positioning and size of the dots on a nanometer length, e.g. for electronically addressing of individual dots. This can be realized by so-called templated self-assembly, which combines top-down lithography with bottom-up selfassembly. In this process the lithographically defined pits serve as pre-defined nucleation points for the epitaxially grown quantum dots. In this thesis, extreme ultraviolet interference lithography at a wavelength of e=13.4 nm is employed for prepatterning of the Si substrates. This technique allows the precise and fast fabrication of high-resolution templates with a high degree of reproducibility. The subsequent epitaxial deposition is either performed by molecular beam epitaxy or low-pressure chemical vapour deposition. It is shown that the dot nucleation on pre-patterned substrates depends strongly on the lithography parameters, e.g. size and periodicity of the pits, as well as on the epitaxy parameters, e.g. growth temperature or material coverage. The interrelations are carefully analyzed by means of scanning force microscopy, transmission electron microscopy and X-ray diffraction measurements. Provided that correct template and overgrowth parameters are chosen, perfectly aligned and uniform SiGe quantum dot arrays of different period, size as well as symmetry are created. In particular, the quantum dot arrays with the so far smallest period (35 nm) and smallest size dispersion are fabricated in this thesis. Furthermore, the strain fields of the underlying quantum dots allow the fabrication of vertically aligned quantum dot stacks. Combining lateral and vertical dot alignment results in three

  5. Mode Competition in Dual-Mode Quantum Dots Semiconductor Microlaser

    CERN Document Server

    Chusseau, Laurent; Viktorovitch, P; Letartre, Xavier

    2013-01-01

    This paper describes the modeling of quantum dots lasers with the aim of assessing the conditions for stable cw dual-mode operation when the mode separation lies in the THz range. Several possible models suited for InAs quantum dots in InP barriers are analytically evaluated, in particular quantum dots electrically coupled through a direct exchange of excitation by the wetting layer or quantum dots optically coupled through the homogeneous broadening of their optical gain. A stable dual-mode regime is shown possible in all cases when quantum dots are used as active layer whereas a gain medium of quantum well or bulk type inevitably leads to bistable behavior. The choice of a quantum dots gain medium perfectly matched the production of dual-mode lasers devoted to THz generation by photomixing.

  6. Modified magnetic quantum dot with electric confining potentials

    International Nuclear Information System (INIS)

    The electronic properties of a modified magnetic quantum dot are studied. The modified magnetic quantum dot is a quantum structure that is formed by spatially inhomogeneous distributions of magnetic fields. Electrons are magnetically confined to the plane where the magnetic fields inside and outside the dot are different from each other. The energy spectrum exhibits quite different features depending on the directions of the magnetic fields inside and outside the dot. In particular, the case of opposite directions of the fields is more interesting than that of the same direction. An electrostatic potential is introduced to the system to study the effects of an electric confining potential on the eigenenergy of a single electron in the modified magnetic quantum dot. The additional potential raises the whole energy spectrum and changes its shape. The ground-state angular momentum transitions occurring in a bare modified magnetic quantum dot disappear on introduction of the additional parabolic potential

  7. Ac response of a coupled double quantum dot

    Institute of Scientific and Technical Information of China (English)

    Xu Jie; W.Z. Shangguan; Zhan Shi-Chang

    2005-01-01

    The effect of phase-breaking process on the ac response of a coupled double quantum dot is studied in this paper based on the nonequilibrium Green function formalism. A general expression is derived for the ac current in the presence of electron-phonon interaction. The ac conductance is numerically computed and the results are compared with those in [Anatram M P and Datts S 1995 Phys. Rev. B 51 7632]. Our results reveal that the inter-dot electron tunnelling interplays with that between dots and electron reservoirs, and contributes prominently to the ac current when inter-dot tunnelling coupling is much larger than the tunnelling coupling between dots and electron reservoirs. In addition, the phase-breaking process is found to have a significant effect on the ac transport through the coupled double dot.

  8. Single quantum dots fundamentals, applications, and new concepts

    CERN Document Server

    2003-01-01

    This book reviews recent advances in the exciting and rapid growing field of semiconductor quantum dots by contributions from some of the most prominent researchers in the field. Special focus is given to the optical and electronic properties of single quantum dots due to their potential applications in devices operating with single electrons and/or single photons. This includes quantum dots in electric and magnetic fields, cavity-quantum electrodynamics, nonclassical light generation, and coherent optical control of excitons. Single Quantum Dots also addresses various growth techniques as well as potential device applications such as quantum dot lasers, and new concepts like a single-photon source, and a single quantum dot laser.

  9. Quantum Dots and Their Multimodal Applications: A Review

    Directory of Open Access Journals (Sweden)

    Paul H. Holloway

    2010-03-01

    Full Text Available Semiconducting quantum dots, whose particle sizes are in the nanometer range, have very unusual properties. The quantum dots have band gaps that depend in a complicated fashion upon a number of factors, described in the article. Processing-structure-properties-performance relationships are reviewed for compound semiconducting quantum dots. Various methods for synthesizing these quantum dots are discussed, as well as their resulting properties. Quantum states and confinement of their excitons may shift their optical absorption and emission energies. Such effects are important for tuning their luminescence stimulated by photons (photoluminescence or electric field (electroluminescence. In this article, decoupling of quantum effects on excitation and emission are described, along with the use of quantum dots as sensitizers in phosphors. In addition, we reviewed the multimodal applications of quantum dots, including in electroluminescence device, solar cell and biological imaging.

  10. Controlled coupling of quantum dots to nanowire plasmons

    International Nuclear Information System (INIS)

    Full text: The diameter of dielectric waveguides is limited by the wavelength of the guided light. In contrast, gold and silver nanowires can sustain propagating plasmon modes even for significantly smaller dimensions. Furthermore the strong eld localization of the nanowire plasmon modes leads to a strong interaction with nearby quantum emitters such as quantum dots. We use electron beam lithography, rst, to fabricate silver nanowires and, second, to position a few dots close to one nanowire end in a template-assisted process. Scanning a focused laser spot over the nanowire ends, we demonstrate both, the excitation of nanowire modes by quantum dots and the addressing of the same dots by plasmons. We use the fluorescence signals to quantify the quantum dots/plasmon coupling and show that part of the plasmon-induced dot fluorescence couples back to plasmonic modes. (author)

  11. Quantum dot spectroscopy using a single phosphorus donor

    Science.gov (United States)

    Büch, Holger; Fuechsle, Martin; Baker, William; House, Matthew G.; Simmons, Michelle Y.

    2015-12-01

    Using a deterministic single P donor placed with atomic precision accuracy next to a nanoscale silicon quantum dot, we present a way to analyze the energy spectrum of small quantum dots in silicon by tunnel-coupled transport measurements. The energy-level structure of the quantum dot is observed as resonance features within the transport bias triangles when the donor chemical potential is aligned with states within the quantum dot as confirmed by a numeric rate equation solver SIMON. This technique allows us to independently extract the quantum dot level structure irrespective of the density of states in the leads. Such a method is useful for the investigation of silicon quantum dots in the few-electron regime where the level structure is governed by an intricate interplay between the spin- and the valley-orbit degrees of freedom.

  12. A SDMS Model: Early Warning Coordination Centres

    Science.gov (United States)

    Santos-Reyes, Jaime

    2010-05-01

    Following the tsunami disaster in 2004, the General Secretary of the United Nations (UN) Kofi Annan called for a global early warning system for all hazards and for all communities. He also requested the ISDR (International Strategy fort Disaster Reduction) and its UN partners to conduct a global survey of capacities, gaps and opportunities in relation to early warning systems. The produced report, "Global survey of Early Warning Systems", concluded that there are many gaps and shortcomings and that much progress has been made on early warning systems and great capabilities are available around the world. However, it may be argued that an early warning system (EWS) may not be enough to prevent fatalities due to a natural hazard; i.e., it should be seen as part of a ‘wider' or total system. Furthermore, an EWS may work very well when assessed individually but it is not clear whether it will contribute to accomplish the purpose of the ‘total disaster management system'; i.e., to prevent fatalities. For instance, a regional EWS may only work if it is well co-ordinated with the local warning and emergency response systems that ensure that the warning is received, communicated and acted upon by the potentially affected communities. It may be argued that without these local measures being in place, a regional EWS will have little impact in saving lives. Researchers argued that unless people are warned in remote areas, the technology is useless; for instance McGuire [5] argues that: "I have no doubt that the technical element of the warning system will work very well,"…"But there has to be an effective and efficient communications cascade from the warning centre to the fisherman on the beach and his family and the bar owners." Similarly, McFadden [6] states that: "There's no point in spending all the money on a fancy monitoring and a fancy analysis system unless we can make sure the infrastructure for the broadcast system is there,"… "That's going to require a lot

  13. Study of inter-dot coupling in nano-patterned permalloy dots array

    International Nuclear Information System (INIS)

    We present a series of studies on interdot coupling in the nanometer-scaled permalloy dots array. A standard electron beam lithography in conjunction with lift-off process was employed for patterning 30 nm thick of millions of permalloy dots array with diameter (D) of 500 nm and the aspect ratio S/D of spacing (S) to diameter ranging from 0.2 to 1.25. The magnetization reversal processes were identified to evolve through the vortex nucleation, movement, and annihilation based on magnetic force microscopy (MFM) imaging in the presence of external magnetic fields. The nucleation field, annihilation field, and moving rate of vortex core were analyzed using M-H loops measured by the alternating gradient magnetometer (AGM). These behaviors are associated with the dipole-dipole interaction in dots array with various interdot spacings.

  14. Establishing a National Nuclear Security Support Centre

    International Nuclear Information System (INIS)

    The responsibility for creating and sustaining a nuclear security regime for the protection of nuclear and other radiological material clearly belongs to the State. The nuclear security regime resembles the layers of an onion, with the equipment and personnel securing the borders and ports representing the outer layer, and nuclear power, research reactors and nuclear medicine facilities representing the inner layers, and the actual target material representing the core. Components of any nuclear security regime include not only technological systems, but the human resources needed to manage, operate, administer and maintain equipment, including hardware and software. This publication provides practical guidance on the establishment and maintenance of a national nuclear security support centre (NSSC) as a means to ensure nuclear security sustainability in a State. An NSSC's basic purpose is to provide a national focal point for passing ownership of nuclear security knowledge and associated technical skills to the competent authorities involved in nuclear security. It describes processes and methodologies that can be used by a State to analyse the essential elements of information in a manner that allows several aspects of long term, systemic sustainability of nuclear security to be addressed. Processes such as the systematic approach to training, sometimes referred to as instructional system design, are the cornerstone of the NSSC concept. Proper analysis can provide States with data on the number of personnel requiring training and instructors needed, scale and scope of training, technical and scientific support venues, and details on the type and number of training aids or simulators required so that operational systems are not compromised in any way. Specific regulatory guidance, equipment or technology lists, or specifications/design of protection systems are not included in this publication. For such details, the following IAEA publications should be consulted

  15. Hokkaido University Nuclear Reaction Data Centre (JCPRG)

    International Nuclear Information System (INIS)

    A research project to compile Charged-Particle Nuclear Reaction Data was initiated in 1974, which was approved by the Theoretical Nuclear Physics Society and the Experimental Nuclear Physics Society in Japan. When this project started, a mutual agreement with the JAERI Nuclear Data Centre was concluded; this Study Group would be responsible for Charged- Particle Nuclear Reaction Data while JAERI would be in charge of Nuclear Neutron Data. The original database (NRDF, Nuclear Reaction Data File) was devised by the Study Group under the sponsorship of the Japanese Ministry of Education, Science and Culture through the Grant-in-Aid for Scientific Research. With data storage and retrieval functions added to the original NRDF system, the project developed from the stage of research and development to the practical working stage of data compilation and data dissemination in 1987. Subsequently, the Study Group was reorganized to become the Japan Charged-Particle Nuclear Reaction Data Group (JCPRG) in NRDC, and was assigned an annual budget through the Nuclear Physics Laboratory, Department of Physics, Hokkaido University by the Ministry of Education, Science and Culture. This regular JCPRG budget ended in 2001, and was replaced by a yearly competitive process. The primary aims of JCPRG are to construct and provide an academic-oriented database according to an original and unique format by compiling and storing all charged-particle nuclear reaction data produced with Japanese accelerators. JCPRG is also responsible for transforming NRDF to EXFOR format, and sending these files to IAEA-NDS. On April 1, 2007, the Japan Charged-Particle Nuclear Reaction Data Group (JCPRG) was reorganized to the Hokkaido University Nuclear Reaction Data Centre (JCPRG) as a measure taken in the Faculty of Science, Hokkaido University. At the same time, the graduate school collaboration field ''Nuclear Data'' science with Japan Atomic Energy Agency (JAEA) was established in the Department of

  16. Electron States of Few-Electron Quantum Dots

    Institute of Scientific and Technical Information of China (English)

    戴振宏; 孙金祚; 张立德; 李作宏; 黄士勇; 隋鹏飞

    2002-01-01

    We study few-electron semiconductor quantum dots using the unrestricted Hartree-Fock-Roothaan method based on the Gaussian basis. Our emphasis is on the energy level calculation for quantum dots. The confinement potential in a quantum dot is assumed to be in a form of three-dimensional spherical finite potential well. Some valuable results, such as the rearrangement of the energy level, have been obtained.

  17. Exciton dephasing in single InGaAs quantum dots

    DEFF Research Database (Denmark)

    Leosson, Kristjan; Østergaard, John Erland; Jensen, Jacob Riis;

    2000-01-01

    The homogeneous linewidth of excitonic transitions is a parameter of fundamental physical importance. In self-assembled quantum dot systems, a strong inhomogeneous broadening due to dot size fluctuations masks the homogeneous linewidth associated with transitions between individual states. The ho...... to fast dephasing. We present an investigation of the low-temperature homogeneous linewidth of individual PL lines from MBE-grown In0.5Ga0.5As/GaAs quantum dots....

  18. Exciton lifetime measurements on single silicon quantum dots.

    Science.gov (United States)

    Sangghaleh, Fatemeh; Bruhn, Benjamin; Schmidt, Torsten; Linnros, Jan

    2013-06-01

    We measured the exciton lifetime of single silicon quantum dots, fabricated by electron beam lithography, reactive ion etching and oxidation. The observed photoluminescence decays are of mono-exponential character with a large variation (5-45 μs) from dot to dot, even for the same emission energy. We show that this lifetime variation may be the origin of the heavily debated non-exponential (stretched) decays typically observed for ensemble measurements.

  19. Region-Dot Conversion Fusion Algorithm and Application

    OpenAIRE

    Zhouxing Fu; Mei Wang; Jingyi Du; Hsiung-Cheng Lin; Ningbo Xu; Hongyang Zan

    2014-01-01

    The interior decoration materials and the new furniture using formaldehyde, ammonia, and other poisonous substances are known as the main sources of indoor air pollutions. However, it is still a big challenge to estimate accurately the overall air quality by using the current measuring tools. Accordingly, the region-dot fusion (RDF) algorithm is proposed to evaluate the air quality in this paper. For the conversion from a region to a dot, the region-dot function is firstly defined as the summ...

  20. Nonlinear transport in coupled quantum dots: A stationary probability approach

    Institute of Scientific and Technical Information of China (English)

    GONG JianPing; DUAN SuQing; YAN WeiXian; ZHAO XianGeng

    2009-01-01

    The stationary tunneling current and differential conductance of the coupled quantum dots system with split-gates are calculated by generalizing the Beenaker's linear response theory for the description of the Coulomb-blockade oscillations of the conductance in the single quantum dot. The calculation of the charging diagram in parallel through the double dot as function of the two side-gate voltages shows a remarkable agreement with the recent experimental results by Hatano et al. (Science, 2005, 309: 268-271)

  1. Recent advances in carbon-based dots for electroanalysis.

    Science.gov (United States)

    Yulong, Ying; Xinsheng, Peng

    2016-04-25

    Carbon-based dots represent a new type of quantum dot with unique and well-defined properties owing to their quantum confinement and edge effects, which are widely employed in sensing, light-emitting diodes, nanomedicine, photocatalysis, electrocatalysis, bioimaging, etc. In this review, we update the latest research results of carbon-based dots in this rapidly evolving field of electroanalysis, place emphases on their applications as sensors and give future perspectives for developing more smart sensors.

  2. Polarization anisotropic luminescence of tunable single lateral quantum dot molecules

    Science.gov (United States)

    Hermannstädter, C.; Witzany, M.; Heldmaier, M.; Hafenbrak, R.; Jöns, K. D.; Beirne, G. J.; Michler, P.

    2012-03-01

    We investigate the photoluminescence polarization anisotropy of self-assembled individual lateral InGaAs/GaAs quantum dot molecules. In contrast to similarly grown single quantum dots, the dot molecules exhibit a remarkable degree of linear polarization, which remains almost unchanged when a lateral electric field is applied to tune the exciton wave function and, thus, the luminescence spectral properties. We discuss the nature of this polarization anisotropy and suggest possible causes based on the system's symmetry and heterostructure alloy composition.

  3. Reconfigurable quadruple quantum dots in a silicon nanowire transistor

    OpenAIRE

    Betz, A. C.; Tagliaferri, M. L. V.; Vinet, M.; Broström, M.; Sanquer, M.; Ferguson, A.J.; Gonzalez-Zalba, M. F.

    2016-01-01

    We present a novel reconfigurable metal-oxide-semiconductor multi-gate transistor that can host a quadruple quantum dot in silicon. The device consist of an industrial quadruple-gate silicon nanowire field-effect transistor. Exploiting the corner effect, we study the versatility of the structure in the single quantum dot and the serial double quantum dot regimes and extract the relevant capacitance parameters. We address the fabrication variability of the quadruple-gate approach which, paired...

  4. Polarized quantum dot emission in electrohydrodynamic jet printed photonic crystals

    Energy Technology Data Exchange (ETDEWEB)

    See, Gloria G. [Micro and Nanotechnology Laboratory, Department of Electrical and Computer Engineering, University of Illinois at Urbana-Champaign, 208 North Wright Street, Urbana, Illinois 61801 (United States); Xu, Lu; Nuzzo, Ralph G. [Department of Chemistry, University of Illinois at Urbana-Champaign, 600 South Mathews Avenue, Urbana, Illinois 61801 (United States); Sutanto, Erick; Alleyne, Andrew G. [Mechanical Science and Engineering Department, University of Illinois at Urbana-Champaign, 154 Mechanical Engineering Building, Urbana, Illinois 61801 (United States); Cunningham, Brian T. [Micro and Nanotechnology Laboratory, Department of Electrical and Computer Engineering, University of Illinois at Urbana-Champaign, 208 North Wright Street, Urbana, Illinois 61801 (United States); Department of Bioengineering, University of Illinois at Urbana-Champaign, 1270 Digital Computer Laboratory, MC-278, Urbana, Illinois 61801 (United States)

    2015-08-03

    Tailored optical output, such as color purity and efficient optical intensity, are critical considerations for displays, particularly in mobile applications. To this end, we demonstrate a replica molded photonic crystal structure with embedded quantum dots. Electrohydrodynamic jet printing is used to control the position of the quantum dots within the device structure. This results in significantly less waste of the quantum dot material than application through drop-casting or spin coating. In addition, the targeted placement of the quantum dots minimizes any emission outside of the resonant enhancement field, which enables an 8× output enhancement and highly polarized emission from the photonic crystal structure.

  5. Nonequilibrium Electron Transport Through a Quantum Dot from Kubo Formula

    Institute of Scientific and Technical Information of China (English)

    L(U) Rong; ZHANG Guang-Ming

    2005-01-01

    Based on the Kubo formula for an electron tunneling junction, we revisit the nonequilibrium transport properties through a quantum dot. Since the Fermi level of the quantum dot is set by the conduction electrons of the leads, we calculate the electron current from the left side by assuming the quantum dot coupled to the right lead as another side of the tunneling junction, and the other way round is used to calculate the current from the right side. By symmetrizing these two currents, an effective local density states on the dot can be obtained, and is discussed at high and low temperatures, respectively.

  6. Coupling of single quantum dots to a photonic crystal waveguide

    DEFF Research Database (Denmark)

    Lund-Hansen, Toke; Stobbe, Søren; Julsgaard, Brian;

    is coupled efficiently to a single enhanced mode. One popular approach has been to couple single quantum dots to a nanocavity but a limiting factor in this configuration is that in order to apply the photon it should subsequently be coupled out of the cavity, reducing the overall efficiency significantly....... An alternative approach is to couple the quantum dot directly to the propagating mode of a photonic waveguide. We demonstrate the coupling of single quantum dots to a photonic crystal waveguide using time-resolved spontaneous emission measurements. A pronounced effect is seen in the decay rates of dots coupled...

  7. An Exciton Bound to a Neutral Donor in Quantum Dots

    Institute of Scientific and Technical Information of China (English)

    解文方

    2002-01-01

    The binding energies for an exciton (X) trapped in a two-dimensional quantum dot by a neutral donor have been calculated using the method of few-body physics for the heavy hole (σ= 0.196) and the light hole (σr = 0.707).We find that the (D0, X) complex confined in a quantum dot has in general a larger binding energy than those in a two-dimensional quantum well and a three-dimensional bulk semiconductor, and the binding energy increases with the decrease of the dot radius. At dot radius R →∞, we compare our calculated result with the previous results.

  8. Core–shell quantum dots: Properties and applications

    Energy Technology Data Exchange (ETDEWEB)

    Vasudevan, D., E-mail: vasudevand@rediffmail.com [Electrodics and electrocatalysis division, CSIR-CECRI, Karaikudi 630006 (India); Gaddam, Rohit Ranganathan [Amity Institute of Nanotechnology, Amity University, Noida 201301 (India); Trinchi, Adrian; Cole, Ivan [CSIRO Materials Science and Engineering, Clayton South MDC, 3169 (Australia)

    2015-07-05

    Fluorescent quantum dots (QDs) are semiconducting nanocrystals (NCs) that find numerous applications in areas, such as bio labelling, sensors, lasers, light emitting diodes and medicine. Core–shell quantum dots were developed to improve the photoluminescence efficiency of single quantum dots. Capping their surface with organic ligands as well as their extraction into aqueous media enables their use in sensing applications. The current review highlights the importance and applications of core shell quantum dots as well as their surface modifications and applications in the field of medicine and as sensors for chemical and biochemical analysis.

  9. Carbon Dot Based Sensing of Dopamine and Ascorbic Acid

    OpenAIRE

    Upama Baruah; Neelam Gogoi; Achyut Konwar; Manash Jyoti Deka; Devasish Chowdhury; Gitanjali Majumdar

    2014-01-01

    We demonstrate carbon dot based sensor of catecholamine, namely, dopamine and ascorbic acid. Carbon dots (CDs) were prepared from a green source: commercially available Assam tea. The carbon dots prepared from tea had particle sizes of ∼0.8 nm and are fluorescent. Fluorescence of the carbon dots was found to be quenched in the presence of dopamine and ascorbic acid with greater sensitivity for dopamine. The minimum detectable limits were determined to be 33 μM and 98 μM for dopamine and ascor...

  10. Highly fluorescent xerogels with entrapped carbon dots for organic scintillators

    Energy Technology Data Exchange (ETDEWEB)

    Quaranta, A., E-mail: quaranta@ing.unitn.it [University of Trento, Department of Industrial Engineering, via Mesiano, 77, 38123 Trento (Italy); Laboratori Nazionali di Legnaro, INFN, Viale dell' Università, 2, 35020 Legnaro (PD) (Italy); Carturan, S. [Laboratori Nazionali di Legnaro, INFN, Viale dell' Università, 2, 35020 Legnaro (PD) (Italy); University of Padova, Department of Physics and Astronomy “Galileo Galilei”, Via Marzolo, 8, 35131 Padova (Italy); Campagnaro, A.; Dalla Palma, M. [University of Trento, Department of Industrial Engineering, via Mesiano, 77, 38123 Trento (Italy); Laboratori Nazionali di Legnaro, INFN, Viale dell' Università, 2, 35020 Legnaro (PD) (Italy); Giarola, M.; Daldosso, N. [University of Verona, Department of Informatics, Strada le Grazie,15, 37134 Verona (Italy); Maggioni, G. [Laboratori Nazionali di Legnaro, INFN, Viale dell' Università, 2, 35020 Legnaro (PD) (Italy); University of Padova, Department of Physics and Astronomy “Galileo Galilei”, Via Marzolo, 8, 35131 Padova (Italy); Mariotto, G. [University of Verona, Department of Informatics, Strada le Grazie,15, 37134 Verona (Italy)

    2014-02-28

    Organically modified silicate thin film and bulk samples were prepared using [3-(2-aminoethylamino)propyl]trimethoxysilane (AEAP-TMOS) as precursor with the addition of different amounts of AEAP-TMOS functionalized C-dots, prepared by reaction of AEAP-TMOS and citric acid at high temperature. The synthesis of surface functionalized C-dots was followed by Fourier Transform Infrared (FTIR) spectroscopy, and the C-dots optical properties were characterized by optical absorption and UV–vis fluorescence. Thin xerogel films and bulk samples were studied by FTIR, Raman and fluorescence spectroscopy. Intense blue-green emission was observed by UV excitation of functionalized C-dots. Carbon quantum dot (CQD) luminescence was preserved also in the xerogel matrices, and the energy transfer from the matrix to CQDs, which is a key characteristic for scintillation detectors, was investigated in the two systems. - Highlights: • Functionalized carbon dots were synthesized. • Carbon dots were dispersed in hybrid xerogel bulk and thin film. • Carbon dots exhibit a strong tunable blue luminescence. • Xerogels were characterized by FT-IR, Raman and fluorescence spectroscopies. • Energy transfer processes were evidenced between C-dots and xerogel matrix.

  11. 我是中国DotA的希望(一)

    Institute of Scientific and Technical Information of China (English)

    少小帅

    2010-01-01

    我叫贾鹏我叫贾鹏,我是中国DotA的希望。他们一直这么评价我,而我对此深信不疑。在这个全民DotA的时代,我也不例外。我DotA玩的怎么样,我不好去评价,和我一起DotA的兄弟们是这么评价我的,"前期打得没的说!"邱涵说;"Gank打得没的说!"程龙说;

  12. Polarized quantum dot emission in electrohydrodynamic jet printed photonic crystals

    International Nuclear Information System (INIS)

    Tailored optical output, such as color purity and efficient optical intensity, are critical considerations for displays, particularly in mobile applications. To this end, we demonstrate a replica molded photonic crystal structure with embedded quantum dots. Electrohydrodynamic jet printing is used to control the position of the quantum dots within the device structure. This results in significantly less waste of the quantum dot material than application through drop-casting or spin coating. In addition, the targeted placement of the quantum dots minimizes any emission outside of the resonant enhancement field, which enables an 8× output enhancement and highly polarized emission from the photonic crystal structure

  13. Electric and Magnetic Interaction between Quantum Dots and Light

    DEFF Research Database (Denmark)

    Tighineanu, Petru

    a future challenge for the droplet-epitaxy technique. A multipolar theory of spontaneous emission from quantum dots is developed to explain the recent observation that In(Ga)As quantum dots break the dipole theory. The analysis yields a large mesoscopic moment, which contains magnetic-dipole and electric......-matter interaction of both electric and magnetic character. Our study demonstrates that In(Ga)As quantum dots lack parity symmetry and, as consequence, can be employed for locally probing the parity symmetry of complex photonic nanostructures. This opens the prospect for interfacing quantum dots with optical...

  14. Second-harmonic imaging of semiconductor quantum dots

    DEFF Research Database (Denmark)

    Østergaard, John Erland; Bozhevolnyi, Sergey I.; Pedersen, Kjeld;

    2000-01-01

    Resonant second-harmonic generation is observed at room temperature in reflection from self-assembled InAlGaAs quantum dots grown on a GaAs (001) substrate. The detected second-harmonic signal peaks at a pump wavelength of similar to 885 nm corresponding to the quantum-dot photoluminescence maxim...... observe that second-harmonic images of the quantum-dot surface structure show wavelength-dependent spatial variations. Imaging at different wavelength is used to demonstrate second-harmonic generation from the semiconductor quantum dots. (C) 2000 American Institute of Physics....

  15. The Centres for Environment-friendly Energy Research (FME)

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    2011-07-01

    High expectations for Norway's Centres for Environment-friendly Energy Research (FME).The FME centres address a broad range of areas, allcentral to developing the energy sector of the future. The activities of the eight centres established in 2009 focus on renewable energy, raising energy efficiency, energy planning, and carbon capture and storage (CCS). In 2011 three new FME centres were established which focus on social science-related energy research. The FME scheme is a direct follow-up of the broad-based political agreement on climate policy achieved in the Storting in January 2008, and of the national RandD Energi21 strategy submitted in February 2008 to the Ministry of Petroleum and Energy. In April 2008 the Research Council of Norway's Executive Board decided to launch a process to establish centres for environment-friendly energy research, and a funding announcement was issued that same year. In 2010 it was decided that additional FME centres would be established in the field of social science-related energy research. After a thorough assessment of each project (based on feasibility, scientific merit, potential to generate value creation and innovation, and composition of the consortium) eight applicants were selected to become FME centres in February 2009. A new call for proposals was issued in 2010, and three more centres were awarded FME status in February 2011. The objective of the FME scheme is to establish time-limited research centres which conduct concentrated, focused and long-term research of high international calibre in order to solve specific challenges in the energy sphere. The selected centres must exhibit higher goals, a longer-term perspective and a more concentrated focus than is required under other funding instruments for the same scientific area. The make-up of the centres is critical to achieving this objective. The centres bring together Norway's leading research institutions and key players in private enterprise, the

  16. SMM DotA大赛结束中国DotA战队囊括三甲

    Institute of Scientific and Technical Information of China (English)

    2009-01-01

    11月27至29日,国外著名DotA大赛Sendi Mutiara Multimedia Grand National DotA Tournament:Grand Firlals 2009(以下简称SMM09)在马来西亚马六甲州进行了为期三天的精彩大战.最终来自中国的三支战队sGty、cD、EHOME囊括三甲。成为SMM09的最大赢家。

  17. Emission switching in carbon dots coated CdTe quantum dots driving by pH dependent hetero-interactions

    Energy Technology Data Exchange (ETDEWEB)

    Dai, Xiao; Wang, Hao; Yi, Qinghua; Wang, Yun; Cong, Shan; Zhao, Jie; Sun, Yinghui; Zou, Guifu, E-mail: zouguifu@suda.edu.cn, E-mail: jiexiong@uestc.edu.cn [College of Physics, Optoelectronics and Energy and Collaborative Innovation Center of Suzhou Nano Science and Technology, Soochow University, Suzhou 215006 (China); Qian, Zhicheng [School of Electronic and Information Engineering, Xi' an Jiaotong University, Xi' an 710049 (China); Huang, Jianwen; Xiong, Jie, E-mail: zouguifu@suda.edu.cn, E-mail: jiexiong@uestc.edu.cn [State Key Laboratory of Electronic Thin Films and Integrated Devices, University of Electronic Science and Technology of China, Chengdu 610054 (China); Luo, Hongmei [Department of Chemical and Materials Engineering, New Mexico State University, Las Cruces, New Mexico 88003 (United States)

    2015-11-16

    Due to the different emission mechanism between fluorescent carbon dots and semiconductor quantum dots (QDs), it is of interest to explore the potential emission in hetero-structured carbon dots/semiconducting QDs. Herein, we design carbon dots coated CdTe QDs (CDQDs) and investigate their inherent emission. We demonstrate switchable emission for the hetero-interactions of the CDQDs. Optical analyses indicate electron transfer between the carbon dots and the CdTe QDs. A heterojunction electron process is proposed as the driving mechanism based on N atom protonation of the carbon dots. This work advances our understanding of the interaction mechanism of the heterostructured CDQDs and benefits the future development of optoelectronic nanodevices with new functionalities.

  18. The LHC Physics Centre at CERN

    CERN Multimedia

    CERN Bulletin

    2010-01-01

    As the LHC goes on line for its first exploration of the new high-energy frontier, CERN is also getting ready to enhance the support it provides for the analysis and interpretation of the emerging data.    The LHC Physics Centre at CERN (LPCC) has started up over the past couple of months, beginning with a series of initiatives ranging from Workshops to lectures for students. More details about the LPCC will be featured in a forthcoming Bulletin article. In the meantime, you can consult the LPCC web page, now available at http://cern.ch/lpcc. This offers the high energy physics community a portal to the LPCC's activities, as well as to useful resources, tools and information about the LHC physics programme, the progress of accelerator operations, relevant workshops and events around the world, and much more. The LPCC will shortly begin issuing a weekly bulletin of its own, distributed by e-mail. Members of the CERN physics community and subscribers to the CERN Bulletin will receive the ...

  19. Rockshire Care Centre, Rockshire Road, Ferrybank, Waterford.

    LENUS (Irish Health Repository)

    Bushe, Chris J

    2008-01-01

    BACKGROUND: Weight gain is commonly observed during psychotropic treatments for chronic forms of severe mental illness and is most rapid during the early treatment phases. All formats of behavioural weight intervention programmes have suggested that weight gain can be prevented or reversed in some patients. There is no data on these programmes in acutely unwell inpatients whom may be the major beneficiaries. METHODS: A modular behavioural intervention programme (Solutions for Wellness) used in SMI outpatients since 2002 in Ireland has been adapted for inpatient use. Preliminary data is reported from 5 centres in Ireland. RESULTS: In 47 inpatients the mean weight change was +0.26 kg (SD 2.02) with a median change of 0 kg. Mean follow-up was 23.7 (SD 21.6) days, and median 14 days (range 6-98 days). There was no difference in mean weight change in those patients involved for > 35 days compared with < 35 days (+0.26 kg; 0.25 kg; p = 0.5). Weight loss or maintenance was seen in 70% of patients. CONCLUSION: These preliminary data are supportive of the concept that acutely unwell inpatients with SMI may engage with a behavioural weight programme. Weight change observed contrasts with the significant weight gain often seen in most subjects. Further clinical trials are warranted.

  20. Centre for Nuclear and Accelerator Technologies (CENTA)

    International Nuclear Information System (INIS)

    A Centre for Nuclear and Accelerator Technologies (CENTA) has been established at the Faculty of Mathematics, Physics and Informatics of the Comenius University in Bratislava comprising of a tandem laboratory designed for the Accelerator Mass Spectrometry (AMS) and Ion Beam Analysis (IBA). The 3 MV Pelletron accelerator is a key feature of the equipment which will enable to carry out state of the art research in physical, environmental, material, biological and medical sciences in collaboration with leading European and world laboratories. The laboratory is further equipped with two ion sources - Alphatros (RF source for H and He ions) and MC-SNICS source (target wheel with 40 positions for solid targets), and low and high energy analyzers of ions (all equipment of National Electrostatics Corp., USA). We shall discuss in detail development of methods for analysis of 14C around nuclear power plant in Jaslovske Bohunice, and present results of temporal 14C variations in atmospheric carbon dioxide and in tree rings collected at the monitoring stations in Zlkovce and in Bratislava. (authors)

  1. The LHC Physics Centre at CERN

    CERN Multimedia

    CERN Bulletin

    2010-01-01

    Although raw physics data is produced at CERN, thanks to the GRID its analysis is performed in various institutes worldwide. In addition, workshops, conferences and meetings take place all over the world. The physicist community is decentralized, and CERN must continue to provide intellectual leadership. The LHC Physics Centre is the tool that will make this possible.   Until the early days of LEP, a large part of the scientific activity related to CERN’s experiments was strongly centered at the Laboratory. Few places had the infrastructure to host activities such as the working groups preparing the Yellow Reports, and the limited access to information in the pre-web era made CERN the natural place to learn what was happening in the field. “I remember the days when we, the theorists, would come to CERN just to read the most recent preprints, which were reaching CERN's Library before we could get them in our institutes”, says Michelangelo Mangano, a member of the Theo...

  2. Radio polarimetry of Galactic Centre pulsars

    Science.gov (United States)

    Schnitzeler, D. H. F. M.; Eatough, R. P.; Ferrière, K.; Kramer, M.; Lee, K. J.; Noutsos, A.; Shannon, R. M.

    2016-07-01

    To study the strength and structure of the magnetic field in the Galactic Centre (GC), we measured Faraday rotation of the radio emission of pulsars which are seen towards the GC. Three of these pulsars have the largest rotation measures (RMs) observed in any Galactic object with the exception of Sgr A⋆. Their large dispersion measures, RMs and the large RM variation between these pulsars and other known objects in the GC implies that the pulsars lie in the GC and are not merely seen in projection towards the GC. The large RMs of these pulsars indicate large line-of-sight magnetic field components between ˜ 16 and 33 μG; combined with recent model predictions for the strength of the magnetic field in the GC this implies that the large-scale magnetic field has a very small inclination angle with respect to the plane of the sky (˜12°). Foreground objects like the Radio Arc or possibly an ablated, ionized halo around the molecular cloud G0.11-0.11 could contribute to the large RMs of two of the pulsars. If these pulsars lie behind the Radio Arc or G0.11-0.11 then this proves that low-scattering corridors with lengths ≳100 pc must exist in the GC. This also suggests that future, sensitive observations will be able to detect additional pulsars in the GC. Finally, we show that the GC component in our most accurate electron density model oversimplifies structure in the GC.

  3. Radio polarimetry of Galactic centre pulsars

    CERN Document Server

    Schnitzeler, D H F M; Ferrière, K; Kramer, M; Lee, K J; Noutsos, A; Shannon, R M

    2016-01-01

    To study the strength and structure of the magnetic field in the Galactic centre (GC) we measured Faraday rotation of the radio emission of pulsars which are seen towards the GC. Three of these pulsars have the largest rotation measures (RMs) observed in any Galactic object with the exception of Sgr A*. Their large dispersion measures, RMs and the large RM variation between these pulsars and other known objects in the GC implies that the pulsars lie in the GC and are not merely seen in projection towards the GC. The large RMs of these pulsars indicate large line-of-sight magnetic field components between ~ 16-33 microgauss; combined with recent model predictions for the strength of the magnetic field in the GC this implies that the large-scale magnetic field has a very small inclination angle with respect to the plane of the sky (~ 12 degrees). Foreground objects like the Radio Arc or possibly an ablated, ionized halo around the molecular cloud G0.11-0.11 could contribute to the large RMs of two of the pulsar...

  4. Design Considerations for an Intensive Autism Treatment Centre

    Science.gov (United States)

    Deochand, Neil; Conway, Alissa A.; Fuqua, R. Wayne

    2015-01-01

    Individuals with autistic spectrum disorder (ASD) who display severe and challenging behaviour sometimes require centre-based intensive applied behaviour analysis (ABA) therapy to meet their health, safety and educational needs. Unfortunately, despite the need for centre-based treatment, there is a paucity of empirical research on building and…

  5. The CERN Control Centre is up and running!

    CERN Multimedia

    Maximilien Brice

    2006-01-01

    The CERN Control Centre (CCC) that combines all the control rooms for the accelerators, the cryogenic system and the technical infrastructure came into operation on 1st February. On 1st February, at 2.00 p.m., Patrick Villeton Pachot started the first Technical Infrastructure shift at the brand new CERN Control Centre.

  6. The Discharge Coefficient of a Centre-Pivot Roof Window

    DEFF Research Database (Denmark)

    Iqbal, Ahsan; Afshari, Alireza; Nielsen, Peter V.;

    2012-01-01

    value of discharge coefficient is used. The constant value of discharge coefficient leads to deceptive airflow estimation in the cases of centre-pivot roof windows. The object of this paper is to study and evaluate the discharge coefficient of the centre pivot roof window. Focus is given on...

  7. Continuum states of the two-centre Dirac equation

    International Nuclear Information System (INIS)

    Continuum wave functions of the two-centre Dirac equation are evaluated for positive as well as negative energy states. In particular solutions for superheavy systems and large two-centre distances are investigated. The calculation of phase correlation diagrams provides a reliable tool for the search for resonance states in the negative energy continuum. (orig.)

  8. Opportunity Centred Learning: An Innovation in Enterprise Education?

    Science.gov (United States)

    Rae, David

    2003-01-01

    This paper describes an approach called opportunity centred learning that has been developed by the author and applied in the field of enterprise education. The relationship between opportunity centred learning and existing theory and practice in learning and education is outlined in comparison with problem-based learning and action learning, and…

  9. Using customer contact centres as relationship marketing instruments

    NARCIS (Netherlands)

    Aa, van der Zanna; Bloemer, Josée; Henseler, Jörg

    2015-01-01

    This article investigates whether, to what extent and how customer contact centres influence customer–firm relationships through customer contact centre quality. The proposed model compiles direct and indirect effects of this form of quality on focal relationship marketing constructs, including cust

  10. Importance of patient centred care for various patient groups.

    NARCIS (Netherlands)

    Rademakers, J.J.D.J.M.; Delnoij, D.M.J.; Boer, D. de

    2010-01-01

    Background: Though patient centred care is a somewhat ‘fuzzy’ concept, in general it is considered as something to strive for. However, preliminary evidence suggests that the importance of elements of patient-centred care (PCC), such as communication, information and shared decision making, may vary

  11. Girls' Groups and Boys' Groups at a Municipal Technology Centre

    Science.gov (United States)

    Salminen-Karlsson, Minna

    2007-01-01

    This article describes the Swedish initiative of municipal technology centres from a gender point of view. These centres provide after-school technology education for children aged 6-16. By means of an ethnographic study, the effects of the use of single-sex groups in increasing the interest of girls and boys in technical activities have been…

  12. Perceived customer contact centre quality: conceptual foundation and scale development

    NARCIS (Netherlands)

    Dun, van Zanna; Bloemer, Josée; Henseler, Jörg

    2011-01-01

    Although the quality of the customer contact centre is pivotal for services, a thorough conceptualization and operationalization of perceived customer contact centre quality does not exist. The extensive scale development process moves from focus group sessions for item generation to exploratory and

  13. Problems and Prospects of Education Resource Centres in Nigeria

    Science.gov (United States)

    Ekanem, Johnson Efiong

    2015-01-01

    Nigeria has good policies on Education and one of such policies is the establishment of Education Resource Centres in every State of the Federation, including the Federal Capital Territory, Abuja. The need is clearly articulated in the National Policy on Education. Despite the lofty plan, most of the centres are not fulfilling the need for their…

  14. Call Centres in Denmark 2004 - Strategy, HR Practices & Performance

    DEFF Research Database (Denmark)

    Sørensen, Ole H.; El-Salanti, Nadia

    This survey is the first scientifically based benchmarking study of the Danish call centre industry. The main results from the study are based on answers from 128 call centres, which correspond to a response rate of 65%. The Danish study is part of a global project coordinated by researchers at C...

  15. Reducing cooling energy consumption in data centres and critical facilities

    Science.gov (United States)

    Cross, Gareth

    Given the rise of our everyday reliance on computers in all walks of life, from checking the train times to paying our credit card bills online, the need for computational power is ever increasing. Other than the ever-increasing performance of home Personal Computers (PC's) this reliance has given rise to a new phenomenon in the last 10 years ago. The data centre. Data centres contain vast arrays of IT cabinets loaded with servers that perform millions of computational equations every second. It is these data centres that allow us to continue with our reliance on the internet and the PC. As more and more data centres become necessary due to the increase in computing processing power required for the everyday activities we all take for granted so the energy consumed by these data centres rises. Not only are more and more data centres being constructed daily, but operators are also looking at ways to squeeze more processing from their existing data centres. This in turn leads to greater heat outputs and therefore requires more cooling. Cooling data centres requires a sizeable energy input, indeed to many megawatts per data centre site. Given the large amounts of money dependant on the successful operation of data centres, in particular for data centres operated by financial institutions, the onus is predominantly on ensuring the data centres operate with no technical glitches rather than in an energy conscious fashion. This report aims to investigate the ways and means of reducing energy consumption within data centres without compromising the technology the data centres are designed to house. As well as discussing the individual merits of the technologies and their implementation technical calculations will be undertaken where necessary to determine the levels of energy saving, if any, from each proposal. To enable comparison between each proposal any design calculations within this report will be undertaken against a notional data facility. This data facility will

  16. Photostability of nitrogen-vacancy centres in diamond

    International Nuclear Information System (INIS)

    Full text: The nitrogen-vacancy colour centre is of interest as a potential single photon source and for solid state quantum computing applications. The centre can exist in both a neutrally charged, [NV]0, and negatively charged, [NV]-, state. Both centres are readily identified by their emission spectra, with characteristic zero phonon lines at 575nm and 637nm respectively, and both are considered to be photostable. We have investigated the photostability of single [NV]- centres using confocal fluorescence microscopy and the results are presented here. These results, along with those from ealier ensemble averaged measurements, lead us to conclude that the NV centre is not photostable. Copyright (2005) Australian Institute of Physics

  17. Optimal catchment area and primary PCI centre volume revisited

    DEFF Research Database (Denmark)

    Schoos, Mikkel Malby; Pedersen, Frants; Holmvang, Lene;

    2015-01-01

    baseline, organisational and procedural characteristics. Quality measures were treatment delays and 30-day all-cause mortality. In the three-year study period, 2,066 consecutive pPCIs were performed. After the fusion of the two centres, pPCI procedures increased by 102%, while door-to-balloon remained......AIMS: The currently stated optimal catchment population for a pPCI centre is 300,000-1,100,000, resulting in 200-800 procedures/year. pPCI centres are increasing in number even within small geographic areas. We describe the organisation and quality of care after merging two high-volume centres......, creating one mega centre serving 2.5 million inhabitants, and performing ~1,000 procedures/year. METHODS AND RESULTS: In this descriptive cohort study, we linked individual-level data from the national Central Population Register holding survival status with our in-hospital dedicated PCI database of...

  18. The Electron-Hole Pair in a Single Quantum Dot and That in a Vertically Coupled Quantum Dot

    Institute of Scientific and Technical Information of China (English)

    XIE Wen-Fang; ZHU Wu

    2003-01-01

    The energy spectra of low-lying states of an exciton in a single and a vertically coupled quantum dots arestudied under the influence of a perpendicularly applied magnetic field. Calculations are made by using the method ofnumerical diagonalization of the Hamiltonian within the effective-mass approximation. We also calculated the bindingenergy of the ground and the excited states of an exciton in a single quantum dot and that in a vertically coupledquantum dot as a function of the dot radius for different values of the distance and the magnetic field strength.

  19. The Electron-Hole Pair in a Single Quantum Dot and That in a Vertically Coupled Quantum Dot

    Institute of Scientific and Technical Information of China (English)

    XIEWen-Fang; ZHUWu

    2003-01-01

    The energy spectra of low-lying states of an exciton in a single and a vertically coupled quantum dots are studied under the influence of a perpendicularly applied magnetic field. Calculations are made by using the method of numerical diagonalization of the Hamiltonian within the effective-mass approximation. We also calculated the binding energy of the ground and the excited states of an exciton in a single quantum dot and that in a vertically coupled quantum dot as a function of the dot radius for different vaJues of the distance and the magnetic field strength.

  20. Clinical types of tinea capitis and species identification in children: an experience from tertiary care centres of karachi, pakistan

    International Nuclear Information System (INIS)

    Objective: To study the clinical types of Tinea Capitis and identify species in children reporting to two tertiary care centres of Karachi, Pakistan. Methods: The escriptive, cross-sectional study was conducted at the Dermatology Outpatients' Department, PNS Shifa Hospital and the Institute of Skin Diseases, Karachi, from January 1, 2008 to December 31, 2009. It comprised 202 children with clinical diagnosis of tineacapitis, confirmed by skin scrapings, showing fungal hyphae and spores in 10% potassium hydroxide on direct microscopy. Wood's lamp examination was carried out and the scrapings were cultured on Sabouraud's agar. A detailed dermatological examination was performed for evidence of fungal infection elsewhere in the body. SPSS 19 was used for data analysis. Results: Male-to-female ratio was 1.1:1 and age ranged from 1 to 14 years. The commonest clinical type gray patch was observed in 71 (35.1%) of the patients, black dot in 63 (31.2%), kerion in 50 (24.8%), favus in 10 (5.0%), diffuse pustular in 6 (3.0%), and diffuse scale in 2 (1.0%) patients. The most frequent species grown on culture was Trichophyton(T).Soudanense, followed by T.Tonsurans, T. Schoenleinii, and T.Mentagrophytes respectively. Conclusion: Most of the patients of Tineacapitis presented with gray patch and black dot variety. The most common species identified by culture was Trichophyton Soudanense. Disease was equal in both gender and predominantly affected the population belonging to low and middle socioeconomic class. (author)