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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. Thermodynamic analysis of BiAsO4-H2O

    Directory of Open Access Journals (Sweden)

    M. Baikenov

    2011-12-01

    Full Text Available The present of the work calculated and build up diagram of potential-pH of system BiAsO4-H2O, with using to thermodynamic analysis. There are determined zones of stability of BiAsO4-on tne basis of diagram.

  3. 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.

  4. Simulation experiments on the reaction system of CH4-MgSO4-H2O

    Institute of Scientific and Technical Information of China (English)

    DING KangLe; LI ShuYuan; YUE ChangTao; ZHONG NingNing

    2008-01-01

    H2S-rich gas in carbonate reservoirs is usually attributed to thermochemical sulfate reduction (TSR). In this paper, thermal simulation experiments on the reaction system of CH4-MgSO4-H2O were carried out using autoclave at 425℃-525℃. The threshold temperature for initiating TSR is much lower than our previous studies (550℃). Properties of the reaction products were analyzed by microcoulometry, gas-chromatography (GC), Fourier transform-infrared spectrometry (FT-IR) and X-ray diffraction (XRD) methods. Thermodynamics and reaction kinetics of TSR processes were investigated on the basis of the experimental data. The results show that thermochemical reduction of magnesium sulfate with methane can proceed spontaneously to produce magnesium oxide, hydrogen sulfur, and carbon diox-ide as the main products, and high temperature is thermodynamically favorable to the reaction. Ac-cording to the reaction model, the calculated activation energy of TSR is 101.894 kJ/mol, which is lower than that by most previous studies. Mg2+ may have played a role of catalytic action in the process of TSR. The elementary steps of TSR and reaction mechanism were discussed tentatively. The study can provide important information on the explanation of geochemical depth limit for natural gas and on the generation of high H2S gas in deep carbonates reservoirs.

  5. Ni3Cl2.1(OH)3.9·4H2O, the Ni analogue to Mg3Cl2(OH)4·4H2O.

    Science.gov (United States)

    Bette, Sebastian; Dinnebier, Robert E; Freyer, Daniela

    2014-05-05

    For the first time a basic transition-metal hydrate, Ni3Cl2.1(OH)3.9·4H2O, is found to be isostructural to a main-group metal phase, Mg3Cl2.0(OH)4.0·4H2O. The Ni phase was found as crystalline solid in the course of investigations into the formation of basic nickel(II) chloride phases at 25 and 40 °C in alkaline, concentrated nickel(II) chloride solutions. Ni3Cl2.1(OH)3.9·4H2O was characterized by thermal analysis, IR spectroscopy, scanning electron microscopy, and X-ray powder diffraction. The crystal structure was determined from high-resolution laboratory X-ray powder diffraction data. Ni3Cl2.1(OH)3.9·4H2O crystallizes in space group C2/m (12) with Z = 2, a = 14.9575(4) Å, b = 3.1413(1) Å, c = 10.4818(5) Å, β = 101.482(1)°, and V = 482.50(3) Å(3). The main building unit of the structure is an infinite triple chain of edge-linked distorted NiO6 octahedra. These chains are separated by interstitial one-dimensional zigzag chains of disordered Cl(-) ions and H2O molecules. The crystal structures of Ni3Cl2.1(OH)3.9·4H2O and the isostructural magnesium salt hydrate Mg3Cl2(OH)4·4H2O (2-1-4 phase) are compared in detail.

  6. Spectrophotometric Study of Adduct Formation Between [Co(Salen)PPh3]ClO4.H2O and [Co(7,7'-Dimethylsalen)PPh3]ClO4.H2O with Amines Donors in Acetonitrile

    OpenAIRE

    2010-01-01

    The equilibrium quotient of the adduct formation of [Co(Salen)PPh3]ClO4.H2O and [Co(7,7'-dimethylSalen)PPh3]ClO4.H2O, as acceptor with amines donors are studied by spectrophotometer. Thermodynamics of these pentacoordinate cobalt(III) Schiff-base complexes have been examined with n-butylamine, sec-butylamine, tert-butylamine, benzylamine and diethylamine in constant ionic strength of 0.1 M sodium perchlorate and acetonitrile solvent at room temperature. We aimed to investigate the effects of ...

  7. 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.

  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. Dehydration Kinetics of Zinc Phosphate Tetrahydrate α-Zn3(PO4)2·4H2O Nanoparticle

    Institute of Scientific and Technical Information of China (English)

    YUAN,Ai-Qun; WU,Jian; HUANG,Zai-Yin; ZHOU,Ze-Guang; WEN,Yan-Xuan; TONG,Zhang-Fa

    2007-01-01

    TG-DTG technique and Harcourt-Esson integrated equation were used to study the dehydration process of zinc phosphate tetrahydrate α-Zn3(PO4)2·4H2O nanoparticle and its thermal decomposition kinetics. The results show that there are three stages of dehydration between 300 and 800 K during the thermal decomposition of α-Zn3(PO4)2·4H2O nanoparticle. The first stage is controlled by chemical reaction with an activation energy of 69.48 Kj·mol-1 and a pre-exponential factor of 1.77×106s-1. The second is controlled by nucleation and growth with an activation energy of 78.74 Kj·mol-1 and a pre-exponential factor of 5.86×109s-1. The third is controlled by nucleation and growth with an activation energy of 141.5 kJnnor1 and a pre-exponential factor of 1.01 × 1012 s-1. The kinetic compensative effects not only exist in Arrhenius equation but also in Harcourt-Esson equation. Activation energy E is dependent on both the decomposition fraction a and temperature T.

  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. Magnetostructural correlations for Fe2+ ions at orthorhombic sites in FeCl2·4H2O and FeF2·4H2O crystals modeled by microscopic spin Hamiltonian approach

    Science.gov (United States)

    Zając, Magdalena; Lipiński, Ignacy Eryk; Rudowicz, Czesław

    2016-03-01

    The microscopic spin Hamiltonian (MSH) theory developed up to the fourth-order perturbation theory for 3d4 and 3d6 ions with spin S=2 within the 5D approximation is employed to predict the zero field splitting (ZFS) parameters and the Zeeman electronic (Ze) ones. The SH parameters, measurable by electron magnetic resonance (EMR), are expressed in terms of the microscopic parameters, i.e. the spin-orbit (λ), spin-spin (ρ) coupling constants, and the crystal-field (ligands-field) energy levels (∆i) within the 5D multiplet. The energies, ∆i, are indirectly related with structural data, thus enabling investigation of magnetostructural correlations. As a case study Fe2+ (3d6; S=2) ions at orthorhombic sites in FeCl2·4H2O and FeF2·4H2O crystals are considered. Calculations of the ZFS and Ze parameters are carried out for wide ranges of values of the microscopic parameters using the package MSH/VBA. Dependence of the theoretically determined ZFS parameters bkq (in the Stevens notation) and the Zeeman factors gi on λ, ρ, and ∆i is examined and suitable graphs are presented. The absolute value of dominant ZFS parameter |b20| is predicted to be in the range from nearly 8.5 to 1.4 cm-1. Matching the theoretical SH parameters and the experimental ones enables determination of the suitable values of λ, ρ, and ∆i. The fourth-rank ZFS parameters and the ρ(spin-spin)-related contributions, considered for the first time here, are found important. The MSH predictions may be verified and fine-tuned by high-magnetic field and high-frequency EMR measurements. The method employed here and the present results may be also useful for other structurally related systems.

  15. CuSO4/H2O2-Induced Rapid Deposition of Polydopamine Coatings with High Uniformity and Enhanced Stability.

    Science.gov (United States)

    Zhang, Chao; Ou, Yang; Lei, Wen-Xi; Wan, Ling-Shu; Ji, Jian; Xu, Zhi-Kang

    2016-02-24

    Mussel-inspired polydopamine (PDA) deposition offers a promising route to fabricate multifunctional coatings for various materials. However, PDA deposition is generally a time-consuming process, and PDA coatings are unstable in acidic and alkaline media, as well as in polar organic solvents. We report a strategy to realize the rapid deposition of PDA by using CuSO4/H2O2 as a trigger. Compared to the conventional processes, our strategy shows the fastest deposition rate reported to date, and the PDA coatings exhibit high uniformity and enhanced stability. Furthermore, the PDA-coated porous membranes have excellent hydrophilicity, anti-oxidant properties, and antibacterial performance. This work demonstrates a useful method for the environmentally friendly, cost-effective, and time-saving fabrication of PDA coatings.

  16. 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.

  17. 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.

  18. Experimental determination of the H2SO4/(NH4)2SO4/H2O phase diagram.

    Science.gov (United States)

    Beyer, Keith D; Bothe, Jameson R; Burrmann, Nicola

    2007-01-25

    We have experimentally investigated the water and sulfuric acid-rich regions of the H2SO4/(NH4)2SO4/H2O ternary liquid/solid phase diagram using differential scanning calorimetry (DSC) and infrared spectroscopy of thin films. We present the liquid/solid ternary phase diagram for temperatures below 373 K and H2SO4 concentrations below 60 wt %. We have determined two ternary eutectics and two tributary reaction points for this system in the regions studied. It is also seen that sulfuric acid tetrahydrate (SAT) forms as a metastable solid over a large concentration range. Two true binary systems have been identified: ice/letovicite and SAT/ammonium bisulfate. Finally, we have compared our results to the predictions of the aerosol inorganics model and have found significant differences both in the final melting points and in the location of some of the phase boundaries including a significant discrepancy in the invariant points predicted versus those observed.

  19. 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.

  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. Magnetocaloric effect and thermal conductivity of Gd(OH)3 and Gd2O(OH)4(H2O)2.

    Science.gov (United States)

    Yang, Yan; Zhang, Qian-Chong; Pan, Yin-Yin; Long, La-Sheng; Zheng, Lan-Sun

    2015-04-30

    Magnetocaloric effect (MCE) and thermal conductivity of two gadolinium hydroxides, Gd(OH)3 (1) and Gd2O(OH)4(H2O)2 (2), are investigated. Magnetic studies indicate that both 1 and 2 exhibit antiferromagnetic interaction, and the MCE values for 1 and 2 at 2 K and ΔH = 7 T are 62.00 J kg(-1) K(-1) and 59.09 J kg(-1) K(-1), respectively. Investigation of their thermal conductivity reveals that the thermal conductivity for 1 is significantly better than that for 2.

  2. 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.

  3. Studies on magnetic properties of unique molecular magnet {[FeII(pyrazole)4]2[NbIV(CN)8]•4H2O}n

    Science.gov (United States)

    Konieczny, P.; Pełka, R.; Zieliński, P. M.; Wasiutyński, T.; Pinkowicz, D.; Sieklucka, B.

    2013-01-01

    In this paper magnetic properties of hybrid inorganic-organic compound {[FeII(pyrazole)4]2[NbIV(CN)8]•4H2O}n are presented. This is a three dimensional molecular magnet with well localized magnetic moments, which make it a suitable candidate for testing magnetic models. In order to characterize the magnetic properties of the above compound we performed the AC/DC magnetometry in the range 0-5 T. The special attention was paid to the phase transition at 7.9 K. The study in magnetic field supports magnetic ordering below 7.9 K.

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

    Science.gov (United States)

    Zhang, Jian-Guo; Li, Zhi-Min; Zang, Yan; Zhang, Tong-Lai; Shu, Yuan-Jie; Yang, Li; Power, Philip P

    2010-06-15

    A novel manganese complex Mn(2)(DAT)(2)Cl(4)(H(2)O)(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 Mn(2)(DAT)(2)Cl(4)(H(2)O)(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 degrees 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. 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

  6. SYNTHESIS AND CHARACTERIZATION OF THE LAMELLAR MICROCRYSTALLINE ZINC PHOSPHATE α-Zn3 (PO4)2·4H2O

    Institute of Scientific and Technical Information of China (English)

    Yuan Aiqun; Bai Lijuan; Ma Shaomei; Tong Zhangfa

    2006-01-01

    Objective To study the structural and anticorrosive property of microcrystalline α-Zn3 (PO4)2 ·4H2O. Methods Zinc phosphate was prepared from zinc acetate and orthophosphate acid in aqueous solution.Structural characteristics of products were investigated by XRD, RAMAN, FTIR, TG-DTA, SEM, surface area,particle size distribution, and density measurements. Results The title compound, a highly crystalline, micronized (A), c0 =5. 0304(A), V=975.86 (A)3. Its specific area is 0. 701 m2/g, density 3. 1612 g/m3 , and average size 4.75μm . Conclusion Comparing with commercial Zinc phosphate, the synthesized iamellar microcrystalline zinc phosphate had excellent anticorrosive property and dispersibility.

  7. The Crystal and Molecular Structure of a New Macrocyclic Ligand, (H6BDBPH)Br6·4H2O

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    The hexahydro-bromide salt of a new 24-membered hexaaza diphenol macrocyclic ligand, (H6BDBPH)Br6·4H2O (C26H56N6O6Br6, M, = 1028.23), crystallizes in the monoclinic system, space group P21/c, with cell parameters: a = 14. 441(5), b=11.482(4), c=12.090(6)A, β=96.92°, V= 1990 (1)A3, Z=2, Dc=1. 716 g/cm3; F(000) = 1024. MoKa radiation, λ= 0. 71013A ), R = 0.0643 and wR = 0. 1356 for 3507 independent reflections with I > 2σ (I). The macrocyclic ligand adapts chair form, and the crystallographic inversion center is located in the macrocyclic cavity, and the six bromide ions and four water molecules are situated symmetrically outside the macrocyclic cavity.

  8. 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.

  9. 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.

  10. Syntheses and Crystal Structures of Two Cyano-bridged Bimetallic Complexes [Ce(DMSO)4(H2O)3Fe(CN)6]·H2O and [La(DMSO)4(H2O)3Co(CN)6]·H2O (DMSO = Dimethylsulfoxide)

    Institute of Scientific and Technical Information of China (English)

    ZHAO Zhen-Qian; CHEN Wen-Tong; LIU Xi; CAI Li-Zhen; GUO Guo-Cong; HUANG Jin-Shun

    2006-01-01

    Two new bimetallic cyano-bridged complexes [Ce(DMSO)4(H2O)3Fe(CN)6]·H2O 1 and [La(DMSO)4(H2O)3Co(CN)6]·H2O 2 have been prepared by the ball milling reaction method and structurally characterized by X-ray single-crystal structure analyses. Crystallographic data for 1:C14H32CeFeN6O8S4, Mr = 736.67, monoclinic, space group P21/n, a = 14.952(1), b =13.7276(9), c = 15.392(1) (A), β = 108.288(1)°, V = 2999.6(4) (A)3, Z = 4, Dc= 1.631 g/cm3,μ =2.304 mm-1, F(000) = 1480, R = 0.0593 and wR = 0.1611; and those for 2: C14H32CoLaN6O8S4,Mr=738.54, monoclinic, space group P21/n, a = 14.945(3), b = 13.731(3), c = 15.300(3) (A), β=107.806(1)°, V= 2989.3(11) (A)3, Z = 4, Dc = 1.641 g/cm3,μ = 2.288 mm-1, F(000) = 1480, R =0.0383 and wR = 0.1132. In both complexes the lanthanide ion is eight-coordinated in a square antiprism arrangement, and the Fe(Ⅲ) or Co(Ⅲ) ion in a nearly regular octahedral environment.The [LnM(CN)6(DMSO)4(H2O)3]·H2O (Ln = Ce and M = Fe for 1; Ln = La and M = Co for 2)species are held together via hydrogen bonds by coordinated water molecules, lattice water molecules and nitrogen atoms of cyanide groups to form a three-dimensional framework.

  11. Preparation,Crystal Structure and Thermal Analyses of a Nitrogen-rich Coordination Compound [Co(DAT)6](PA)2·4H2O

    Institute of Scientific and Technical Information of China (English)

    CUI Yan; ZHANG Jian-Guo; ZHANG Tong-Lai; YANG Li; ZANG Yan; SHU Yuan-Jie

    2008-01-01

    A new coordination compound [Co(DAT)6](PA)2·4H2O has been prepared by using 1,5-diaminotetrazole(DAT)as ligands and picrate(PA)as acidic anions,and structurally characterized by X-ray single crystal diffraction,ele-mental analysis and FT-IR spectroscopy.The cobalt(Ⅱ)cation coordinates with six N atoms from six bulky DAT molecules to form a six-coordinated and slightly distorted octahedral configuration.The coordination cation is situ-ated between two PA anions whose benzene-ring planes are parallel to each other.The coordination cation and the lecular units are linked together by the intermolecular hydrogen bonds to form the crystal structure,in the formation investigated by using DSC,TG-DTG and FT-IR analyses.The kinetic parameters of the first exothermic process of the title compound were studied by applying the Kissinger's and Ozawa-Doyle's methods.

  12. 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.

  13. Preparation of NiO nanoparticles from Ni(OH)2·NiCO3·4H2O precursor by mechanical activation

    Science.gov (United States)

    Ahmadisoltansaraei, Kolsoom; Moghaddam, Javad

    2014-07-01

    A mechanical activation process was introduced as a facile method for producing nickel oxide nanopowders. The precursor compound Ni(OH)2·NiCO3·4H2O was synthesized by chemical precipitation. The precursor was milled with NaCl diluent. A high-energy ball milling process led to decomposition of the precursor and subsequent dispersal in NaCl media. Nickel oxide nanocrystalline powders were produced by subsequent heat treatment and water washing. Milling rotation speed, milling time, ball-to-powder ratio (BPR), and nickel chloride-to-precursor ratio were introduced as influential parameters on the wavelength of maximum absorption ( λ max). The effects of these parameters were investigated by the Taguchi method. The optimum conditions for this study were a milling rotation speed of 150 r/min, a milling time of 20 h, a BPR of 15/1, and a NaCl-to-powder weight ratio (NPR) of 6/1. In these conditions, λ max was predicted to be 292 nm. The structural properties of the samples were determined by field emission scanning electron microscopy, X-ray diffraction, and energy dispersive spectrometry.

  14. Preparation of NiO nanoparticles from Ni(OH)2⋅NiCO3⋅4H2O precursor by mechanical activation

    Institute of Scientific and Technical Information of China (English)

    Kolsoom Ahmadisoltansaraei; Javad Moghaddam

    2014-01-01

    A mechanical activation process was introduced as a facile method for producing nickel oxide nanopowders. The precursor com-pound Ni(OH)2⋅NiCO3⋅4H2O was synthesized by chemical precipitation. The precursor was milled with NaCl diluent. A high-energy ball milling process led to decomposition of the precursor and subsequent dispersal in NaCl media. Nickel oxide nanocrystalline powders were produced by subsequent heat treatment and water washing. Milling rotation speed, milling time, ball-to-powder ratio (BPR), and nickel chlo-ride-to-precursor ratio were introduced as influential parameters on the wavelength of maximum absorption (λmax). The effects of these pa-rameters were investigated by the Taguchi method. The optimum conditions for this study were a milling rotation speed of 150 r/min, a mill-ing time of 20 h, a BPR of 15/1, and a NaCl-to-powder weight ratio (NPR) of 6/1. In these conditions,λmax was predicted to be 292 nm. The structural properties of the samples were determined by field emission scanning electron microscopy, X-ray diffraction, and energy dispersive spectrometry.

  15. Structure of Hexakis (imidazole) nickel (Ⅱ) Nitrate Water Solvate: [Ni(Im)6] (NO3)2·4H2O

    Institute of Scientific and Technical Information of China (English)

    JIAN,Fang-Fang(建方方); ZHAO,Pu-Su(赵朴素); XIAO,Hai-Lian(肖海连); ZHANG,Shu-Sheng(张书圣)

    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 discrete Ni(Im)2+6 cation,NO-3 anion and four uncoordinated water molecules.It crystallizes in the hexagonal system,space group P63,with lattice partmeters a=b=0.9003(2)nm,c=2.1034(4)nm,and Z=2.The The(Ⅱ)ion is centro- symmetric octahedron geometry with the NiN6 core.Siximidazole molecules are coordinated to each nickel(Ⅱ)atom through its tertiary nitrogen atom.The short and long bond distances 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 network which stabitizesthe crystal structure.

  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 A MIXED-LIGANDS COMPLEX [CU(R-LACT)(O-PHEN)(H2O)]•4H2O

    Institute of Scientific and Technical Information of China (English)

    ZHANG Qiang; TANG Ding-xing

    2014-01-01

    A mixed-ligands complex with the formula of [Cu(R-lact)(o-phen)(H2O)]•4H2O was synthesized by the reaction of copper carbonate with racemic lactic acid (RS-H2lact), and then with o-phenanthroline(o-phen) in ethanol-water(95%) solution. One of the two obtained com-pounds was dark blue column single crystal and was characterized by elemental analysis, IR spectrum and X-ray single crystal diffraction. The crystal belongs to triclinic system with space group P1, a=7.2825(5) , b=11.7322(8) , c=12.1194(8) , a=65.8280(10)°, β=84.2120(10)°,γ=75.3290(10)°, V=913.88(11) 3, Z=2, Dc=1533kg•m-3, Mr=421.89, μ(MoK\\α)=1.240mm-1,λ=0.71073 , the final R=0.0483 and ωR=0.1199 [I﹥2σ(I)] for 3120 observed reflections, F(000)=438. The copper atom is five coordinated with the distorted square pyramid environment. The five coordinated atoms are two oxygen atoms of depronated hydroxyl group and carboxyl of H2lact, two nitrogen atom of o-phen and one oxygen atom of water molecule.

  18. On the use of overtone and combination bands for the analysis of the CaSO4-H2O system by mid-infrared reflection spectroscopy.

    Science.gov (United States)

    Rosi, Francesca; Daveri, Alessia; Doherty, Brenda; Nazzareni, Sabrina; Brunetti, Brunetto G; Sgamellotti, Antonio; Miliani, Costanza

    2010-08-01

    With the aim of characterizing ground preparations of paintings by infrared reflection spectroscopy, the CaSO(4)-H(2)O system (gypsum/bassanite/anhydrite) has been re-investigated, evaluating and assigning the SO(4)(2-) and OH overtone and combination bands, respectively, in the ranges 1900-2700 cm(-1) and 5000-6000 cm(-1) resulting from reflection and high concentration transmission spectra. The second-order modes have been proven to be highly specific, reliable, and less affected by overlap with bands of organic binders and can hence be exploited for the identification of the sulfate hydration phase using infrared (IR) reflection spectroscopy. Subsequently, the characterization and identification of hydration phases in unknown sulfate-based ground preparations on authentic artworks have been carried out noninvasively by fiber-optic reflection IR spectroscopy and on cross-sections by infrared reflection micro-spectroscopy. The spectroscopic data collected both on standards and artworks have been cross-validated by X-ray diffraction.

  19. 9Mg(OH)(2)·MgCl(2)·4H(2)O, a high temperature phase of the magnesia binder system.

    Science.gov (United States)

    Dinnebier, Robert E; Freyer, Daniela; Bette, Sebastian; Oestreich, Melanie

    2010-11-01

    The metastable phase 9Mg(OH)(2)·MgCl(2)·4H(2)O (9-1-4 phase) was found at the extended metastable isotherm of Mg(OH)(2) in the system MgO-MgCl(2)-H(2)O at 120 °C and occurs as intermediate binder phase during setting of magnesia cement due to temperature development of the setting reaction. The crystal structure of the 9-1-4 phase was solved from high resolution laboratory X-ray powder diffraction data in space group I2/m (C2/m) (a = 22.2832(3) Å, b = 3.13501(4) Å, c = 8.1316(2) Å, β = 97.753(1)°, V = 562.86(2) Å(3), and Z = 1). Structural and characteristical relations of the phases in the system MgO-MgCl(2)-H(2)O can be derived, with which the development of the cement or concrete qualities becomes explainable.

  20. Synthesis and Crystal Structure of a Cyano-bridged Bimetallic Complex: [NdFe(CN)6(DMF)4(H2O)3]·H2O

    Institute of Scientific and Technical Information of China (English)

    李建荣; 郭国聪; 王明盛; 周国伟; 卜显和; 黄锦顺

    2003-01-01

    A new bimetallic cyano-bridged complex, [NdFe(CN)6(DMF)4(H2O)3]@H2O (DMF= N,N-dimethylformamide) 1, has been obtained by the reaction of hexacyanoferrate potassium with neodymium (Ⅲ) chloride in H2O/EtOH/DMF (volume ratio: 2:2:1), and its structure was determined by means of single-crystal X-ray diffraction. The compound crystallizes in space group P21/n of monoclinic system with cell parameters: a = 17.646(1), b = 8.9011(3), c = 19.945(1) A, β = 95.835(2)°, V= 3116.6(3) A3, Z = 4, Dc = 1.536 g/cm3, Mr = 720.66, F(000) = 1456, μ = 2.166 mm-1, R = 0.0386, wR = 0.1120 and S = 1.061. The central Nd (Ⅲ) ion is coordinated by seven oxygen atoms of four DMF molecules and three water molecules and one nitrogen atom of the bridging cyanide in a slightly distorted square-antiprism arrangement, and the Fe (Ⅲ) ion is in an almost octahedral environment coordinated to six cyano-ligands, of which one cyanide ligand bridges the Nd (Ⅲ) ion to form a bimetallic complex. Molecules of complexes in the crystal lattice are held together by hydrogen bonding, forming a three-dimensional framework.

  1. 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.

  2. Mise en évidence d'un nouvel anion à huit atomes de bore dans Tl 4[B 8O 12(OH) 4]H 2O

    Science.gov (United States)

    Touboul, Marcel; Bois, Claudette; Amoussou, Denagnon

    1983-07-01

    The structure solution of an hydrated thallium diborate previously formulated Tl 2B 4O 7 · 2H 2O has led to the correct formula Tl 4[B 8O 12(OH) 4]H 2O. This compound is triclinic with a = 7.221(4)Å, b = 9.494(4)Å, c = 15.592(8)Å, α = 114°.86(4), β = 90°.25(7), γ = 99°.70(4), Z = 2, space group P overline1. Independent reflections numbering 1594 were used in the solution and refinement of the structure to R = 0.039 ( Rw = 0.042). The structure contains a new unit [B 8O 12(OH) 4] -, formed by four BO 4( T) tetrahedra and four BO 3(Δ) triangles. In the Christ and Clark classification for borates ( Phys. Chem. Mineral.2, 59 (1977)), the structural formula should be written [B 7O 10(OH) 3 · OBO(OH)] 4-. A fundamental building block with seven boron atoms is found for the first time; the correspondent fully hydrated polyanion is [B 7O 9(OH) 7] 4-; the shorthand notation is 7 : 3 Δ + 4 T. The units [B 7O 10(OH) 3 · OBO(OH)] 4- or 7 : (3 Δ + 4 T) + Δ are linked together to form an infinite chain. Tl + and H 2O are located between the chains.

  3. Growth, Optical, Mechanical, Dielectric and Theoretical Studies on Potassium Pentaborate Tetrahydrate (KB_5O_8·4H_2O) Single Crystal by Modified Sankaranarayanan-Ramasamy Method

    Institute of Scientific and Technical Information of China (English)

    C. Justin Raj; S. Krishnan; S. Dinakaran; J. Mary Linet; R. Uthrakumar; R. Robert; Jerome Das

    2009-01-01

    A nonlinear optical single crystal of potassium pentaborate tetrahydrate (KB_5O_8·4H_2O) has been grown from aqueous solution by using unidirectional crystal growth method of Sankaranarayanan-Ramasamy (SR) with a due modification in the growth assembly. Potassium pentaborate crystal of 60 mm length and 10 mm diameter has been grown along (100) plane with a growth rate of 3 mm per day within a period of 20 days. The grown crystal was subjected to single crystal X-ray diffraction analysis to confirm that the crystal belongs to the orthorhombic system. Some fundamental data such as valance electron plasma energy, Penn gap, Fermi energy and electronic polarizability of the grown crystal were calculated. The presence of borate in the grown crystal was confirmed by Fourier transform infrared (FTIR) spectroscopy. The optical transmission property of the grown crystal was analyzed using ultra violet (UV) visible spectral analysis. Surface morphology of the growth plane was observed using scanning electron microscopy (SEM). The mechanical strength of the crystals was found out using Vickers microhardness test along the growth axis. Frequency dependent dielectric constant of the grown crystal was studied for various temperatures along (100) plane.

  4. Organically templated uranium(IV) fluorooxalates with layer structures: (H4TREN)[U2F6(C2O4)3].4H2O (TREN = tris(2-aminoethyl)amine) and (H4APPIP)[U2F6(C2O4)3].4H2O (APPIP = 1,4-bis(3-amino-propyl)piperazine).

    Science.gov (United States)

    Wang, Chih-Min; Wu, Yi-Ying; Chen, Pei-Lin; Lii, Kwang-Hwa

    2007-03-14

    Two organically-templated layered uranium(IV) fluorooxalates, (H(4)TREN)[U(2)F(6)(C(2)O(4))(3)].4H(2)O (1) (TREN = tris(2-aminoethyl)amine) and (H(4)APPIP)[U(2)F(6)(C(2)O(4))(3)].4H(2)O (2) (APPIP = 1,4-bis(3-aminopropyl)piperazine), have been synthesized by hydrothermal methods and structurally characterized by single-crystal X-ray diffraction, thermogravimetric analysis, and magnetic susceptibility. Both structures consist of anionic [U(2)F(6)(C(2)O(4))(3)](4-) layers separated by organic ammonium cations and lattice water molecules. The UF(3)O(6) polyhedra are connected by oxalate ligands in different ways within the layers. They are the first examples of organically-templated uranium fluorooxalates. Crystal data for compound 1 follow: monoclinic, P2(1)/c (No. 14), a = 19.1563(5) A, b = 8.9531(2) A, c = 16.6221(4) A, beta = 114.633(1) degrees, and Z = 4. Crystal data for compound are the same as those for 1 except a = 10.3309(8) A, b = 15.564(1) A, c = 17.537(1) A, and beta = 95.430(4) degrees.

  5. Measurements of CO2, CH4, H2O, and HDO over a 2-km Outdoor Path with Dual-Comb Spectroscopy

    Science.gov (United States)

    Rieker, G. B.; Giorgetta, F. R.; Coddington, I.; Swann, W. C.; Sinclair, L. C.; Cromer, C.; Baumann, E.; Newbury, N. R.; Kofler, J.; Petron, G.; Sweeney, C.; Tans, P. P.

    2013-12-01

    We demonstrate simultaneous sensing of CO2, CH4, H2O, and HDO over a 2-km outdoor open air path using dual-frequency-comb absorption spectroscopy (DCS). Our implementation of the DCS technique simultaneously offers broad spectral coverage (>8 THz, 267 cm-1) and fine spectral point spacing (100 MHz, 0.0033 cm-1) with a coherent eye-safe beam. The spectrometer, which is adapted from [Zolot et al., 2012], consists of two mutually coherent Erbium-doped fiber frequency-comb lasers which create a broad spectrum of perfectly spaced narrow linewidth frequency elements (';comb teeth') near 1.6 μm. The comb light is transmitted by a telescope and active steering mirrors from the roof of the NIST Boulder laboratory to a 50-cm flat mirror located 1 km away. The return light is received by a second telescope and carried via multimode fiber to a detector. The greenhouse gas absorption attenuates the teeth from the two combs that are coincident with the relevant molecular resonant frequencies. We purposefully offset the frequencies between the two frequency combs in a Vernier-like fashion so that each pair of comb teeth from the two combs results in a unique rf heterodyne beat frequency on the photodiode. The spectral spacing between subsequent comb teeth pairs is 100 MHz, far lower than the ~4 GHz linewidths of small molecule absorption features in the atmosphere. Because of the narrow comb linewidth, there is an essentially negligible instrument lineshape. The measured absorption spectrum can thus resolve neighboring absorption features of different species, and can be compared directly with HITRAN and recent greenhouse gas absorption models developed for satellite- and ground-based carbon observatories to determine the path-integrated concentrations of the absorbing species. Measurements covering the complete 30013←00001 absorption band of CO2 and absorption features of CH4, H2O and HDO between 1.6-1.67 μm were performed under a variety of atmospheric conditions. During

  6. 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.

  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)

    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.

  8. "Plug and play" full-dimensional ab initio potential energy and dipole moment surfaces and anharmonic vibrational analysis for CH4-H2O.

    Science.gov (United States)

    Qu, Chen; Conte, Riccardo; Houston, Paul L; Bowman, Joel M

    2015-03-28

    The potential energy surface of the methane-water dimer is represented as the sum of a new intrinsic two-body potential energy surface and pre-existing intramolecular potentials for the monomers. Different fits of the CH4-H2O intrinsic two-body energy are reported. All these fits are based on 30 467 ab initio interaction energies computed at CCSD(T)-F12b/haTZ (aug-cc-pVTZ for C and O, cc-pVTZ for H) level of theory. The benchmark fit is a full-dimensional, permutationally-invariant analytical representation with root-mean-square (rms) fitting error of 3.5 cm(-1). Two other computationally more efficient two-body potentials are also reported, albeit with larger rms fitting errors. Of these a compact permutationally invariant fit is shown to be the best one in combining precision and speed of evaluation. An intrinsic two-body dipole moment surface is also obtained, based on MP2/haTZ expectation values, with an rms fitting error of 0.002 au. As with the potential, this dipole moment surface is combined with existing monomer ones to obtain the full surface. The vibrational ground state of the dimer and dissociation energy, D0, are determined by diffusion Monte Carlo calculations, and MULTIMODE calculations are performed for the IR spectrum of the intramolecular modes. The relative accuracy of the different intrinsic two-body potentials is analyzed by comparing the energetics and the harmonic frequencies of the global minimum well, and the maximum impact parameter employed in a sample methane-water scattering calculation.

  9. Magnetocaloric effect in {[Fe(pyrazole)_4]_2[Nb(CN)_8]·4H_2O}{sub n} molecular magnet

    Energy Technology Data Exchange (ETDEWEB)

    Pełka, R., E-mail: robert.pelka@ifj.edu.pl [The H. Niewodniczański Institute of Nuclear Physics Polish Academy of Sciences, Radzikowskiego 152, 31-342 Kraków (Poland); Konieczny, P.; Zieliński, P.M.; Wasiutyński, T. [The H. Niewodniczański Institute of Nuclear Physics Polish Academy of Sciences, Radzikowskiego 152, 31-342 Kraków (Poland); Miyazaki, Y.; Inaba, A. [Research Center for Structural Thermodynamics, Graduate School of Science, Osaka University, Toyonaka, Osaka 560-0043 (Japan); Pinkowicz, D.; Sieklucka, B. [Faculty of Chemistry, Jagiellonian University, Ingardena 3, 30-060 Kraków (Poland)

    2014-03-15

    Magnetocaloric effect in {[Fe(pyrazole)_4]_2[Nb(Cn)_8]·4H_2O}{sub n} molecular magnet is reported. It crystallizes in tetragonal I4{sub 1}/a space group. The compound exhibits a phase transition to a long range magnetically ordered state at T{sub c}≈8.3K. The magnetic entropy change ΔS{sub M} as well as the adiabatic temperature change ΔT{sub ad} due to applied field change μ{sub 0}ΔH=0.1, 0.2, 0.5, 1, 2, 5, 9 T as a function of temperature have been determined by the relaxation calorimetry measurements. The maximum value of ΔS{sub M} for μ{sub 0}ΔH=5T is 4.9 J mol{sup −1} K{sup −1} (4.8 J kg{sup −1} K{sup −1}) at 10.3 K. The corresponding maximum value of ΔT{sub ad} is 2.0 K at 8.9 K. The temperature dependence of the exponent n characterizing the field dependence of ΔS{sub M} has been estimated. It attains the value of 0.64 at the transition temperature, which is consistent with the 3D Heisenberg universality class. - Highlights: • Using the technique of relaxation calorimetry the magnetocaloric effect of a novel molecular magnet is analyzed. • Temperature dependencies of isothermal magnetic entropy change and adiabatic temperature change are estimated. • Scaling behavior of the magnetocaloric effect is discussed.

  10. 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.

  11. Thermodynamic Enthalpy and Internal Energy in the Reaction System C10H8(s) +12O2(g)→10CO2(g)+4H2O(l)%燃烧反应C10H8(s) +12O2(g)→10CO2(g)+4H2O(l)的热力学焓和内能

    Institute of Scientific and Technical Information of China (English)

    高翔; 李鑫华; 汤思聪

    2003-01-01

    Thermodynamic enthalpy, ΔH and internal energy, ΔU in the reaction system C10H8 + 12O2→10CO2+4H2O are determined using an experimental method in our laboratory. Under the experimental conditions, the results calculated show that the reaction combustion enthalpy ΔH is -5093.3?kJ*mol-1 and internal energy ΔU is -5012 kJ*mol-1 on the basis of basic thermodynamic laws. The results are in good agreement with those calculated by theoretical methods. To understand the role of microstructure changes of the reactants and products in determining thermodynamic properties in the reaction system, contributions to entropy, ΔS, enthalpy, ΔH, and heat capacity, Cp(T), from melting and internal configuration change of reactants or products in the reaction are introduced and discussed.%用实验的方法测定了燃烧反应C10H8(s) +12O2(g)10CO2(g)+4H2O(l)的热力学焓ΔH和内能ΔU.根据热力学基本定律用实验数据计算结果表明该燃烧反应焓ΔH=-5093.3kJ.mol-1和反应内能ΔU=-5012kJ*mol-1,与理论计算结果相近似.为了了解反应物和产物的微观结构在该反应热力学性能中所起作用,介绍和讨论了在反应过程中反应物和产物的熔化和内部结构变化对反应熵S,焓H和热容Cp(T)的影响.

  12. 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...

  13. Synthesis, Crystal Structure and Electrochemical Properties of Complex [Ru2 (μ-O2CCH3)4 (H2O)2] PF6%配合物[Ru2(μ-O2CCH3)4(H2O)2]PF6的合成、表征及电化学性质

    Institute of Scientific and Technical Information of China (English)

    严生虎; 姜冬明; 张跃; 刘建武; 沈介发

    2011-01-01

    The title compound, [Ru2 (μ-O2CCH3)4 (H2O)2] PF6, was prepared by treating Ru2 (O2 CCH3)4C1 with methanol aqueous solution at the presence of Ag2SO4 and NH4PF6 through coordinating process. The compound was characterized by elemental analysis, IR spectra, cyclic voltammetry and X-ray single crystal structure analysis. The result reveals that the compound crystallizes in the monoclinic system with space group at C2/c, and a =1. 9 52 3 (9) nm, b = 1. 2 83 0 (6) nm, c =0. 846 8 (4) nm, β=93. 11 (10) and Z = 4. Thermogravimetric analysis was carried out to study the mechanism of thermal decomposition of the complex. The electrochemical property of ruthenium complex were studied by means of cyclic voltametry, the results show that electron transfer between Ru (II) and Ru (III) in electrolysis is quasi-reversible process.%[Ru2(μ-O2CCH3)4(H2O)2]PF6是以Ru2( O2CCH3)4Cl为前体配合物,在甲醇水(体积比7 ∶ 1)溶液中用Ag2SO4和NH4PF6进行脱氯配位反应而得.用元素分析、红外光谱、热重分析、循环伏安、X-衍射单晶结构分析等对其进行表征.晶体结构表明,标题化合物的晶体属单斜晶系,空间群为C2/c,晶胞参数为a=1.9 523 (9) nm,b=1.2830 (6) nm,c=0.8468 (4) nm,β=93.11 (10)°,Z=4.通过热失重分析研究配合物的热分解机理.用循环伏安法对其电化学性质进行表征,结果为一对准可逆的氧化还原峰,表明该配合物的中心金属2价钌原子Ru (Ⅱ)与3价钌原子Ru (Ⅲ)之间存在电子转移.

  14. The measurement of sulfate mineral solubilities in the Na-K-Ca-Cl-SO 4-H 2O system at temperatures of 100, 150 and 200°C

    Science.gov (United States)

    Freyer, Daniela; Voigt, Wolfgang

    2004-01-01

    At T > 100°C development of thermodynamic models suffers from missing experimental data, particularly for solubilities of sulfate minerals in mixed solutions. Solubilities in Na +-K +-Ca 2+-Cl --SO 42-/H 2O subsystems were investigated at 150, 200°C and at selected compositions at 100°C. The apparatus used to examine solid-liquid phase equilibria under hydrothermal conditions has been described. In the system NaCl-CaSO 4-H 2O the missing anhydrite (CaSO 4) solubilities at high NaCl concentrations up to halite saturation have been determined. In the system Na 2SO 4-CaSO 4-H 2O the observed glauberite (Na 2SO 4 · CaSO 4) solubility is higher than that predicted by the high temperature model of Greenberg and Møller (1989), especially at 200°C. At high salt concentrations, solubilities of both anhydrite and glauberite increase with increasing temperature. Stability fields of the minerals syngenite (K 2SO 4 · CaSO 4 · H 2O) and goergeyite (K 2SO 4 · 5 CaSO 4 · H 2O) were determined, and a new phase was found at 200°C in the K 2SO 4-CaSO 4-H 2O system. Chemical and single crystal structure analysis give the formula K 2SO 4 · CaSO 4. The structure is isostructural with palmierite (K 2SO 4 · PbSO 4). The glaserite ("3 K 2SO 4 · Na 2SO 4") appears as solid solution in the system Na 2SO 4-K 2SO 4-H 2O. Its solubility and stoichiometry was determined as a function of solution composition.

  15. 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.

  16. 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.

  17. 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.

  18. X-ray crystallographic and tungsten-183 nuclear magnetic resonance structural studies of the [M4(H2O)2(XW9O34) 2]10- heteropolyanions (M = COII or Zn, X = P or As)

    Science.gov (United States)

    Evans, H.T.; Tourne, C.M.; Tourne, G.F.; Weakley, T.J.R.

    1986-01-01

    The crystal structures of K10[Co4(H2O)2(PW9O 34)2]??22H2O (1) and isomorphous K10[Zn4(H2O)2(AsW9O 34)2]??23H2O (2) have been determined {Mo-K?? radiation, space group P21/n, Z = 2; (1) a = 15.794(2), b = 21.360(2), c = 12.312(1) A??, ?? = 91.96??, R = 0.084 for 3 242 observed reflections [I ??? 3??(I)]; (2) a = 15.842(4), b = 21.327(5), c = 12.308(4) A??, ?? = 92.42(4)??, R = 0.066 for 4 675 observed reflections [F ??? 3??(F)]}. The anions have crystallographic symmetry 1 and non-crystallographic symmetry very close to 2/m (C2h). Each consists of two [XW9O34]9- moieties [??-B isomers; X = P (1) or As (2)] linked via four CoIIO6 or ZnO6 groups. Two Co or Zn atoms each carry a water ligand. The 183W n.m.r. spectra of the anions [Zn4(H2O)2(XW9O34) 2]10- (X = P or As) confirm that the anions retain 2/m symmetry in aqueous solution. Homonuclear coupling constants between 183W atoms are 5.8-9.0 Hz for adjacent WO6 octahedra sharing edges, and 19.6-25.0 Hz for octahedra sharing corners.

  19. 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.

  20. β,β-Isomer of Open-Wells–Dawson Polyoxometalate Containing a Tetra-Iron(III Hydroxide Cluster: [{Fe4(H2O(OH5}(β,β-Si2W18O66]9−

    Directory of Open Access Journals (Sweden)

    Satoshi Matsunaga

    2016-05-01

    Full Text Available The β,β-isomer of open-Wells–Dawson polyoxometalate (POM containing a tetra-iron(III cluster, K9[{Fe4(H2O(OH5}(β,β-Si2W18O66]·17H2O (potassium salt of β,β-Fe4-open, was synthesized by reacting Na9H[A-β-SiW9O34]·23H2O with FeCl3·6H2O at pH 3, and characterized by X-ray crystallography, FTIR, elemental analysis, TG/DTA, UV–Vis, and cyclic voltammetry. X-ray crystallography revealed that the {Fe3+4(H2O(OH5}7+ cluster was included in the open pocket of the β,β-type open-Wells–Dawson polyanion [β,β-Si2W18O66]16− formed by the fusion of two trilacunary β-Keggin POMs, [A-β-SiW9O34]10−, via two W–O–W bonds. The β,β-open-Wells–Dawson polyanion corresponds to an open structure of the standard γ-Wells–Dawson POM. β,β-Fe4-open is the first example of the compound containing a geometrical isomer of α,α-open-Wells–Dawson structural POM.

  1. 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.

  2. 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

  3. Synthesis of Pd(C4H2O4)(C4H8N2)0.5 Complex and the Catalytic Activity for Oxidative Carbonylation of Phenol%配合物Pd(C4H2O4)(C4H8N2)0.5的合成及对苯酚的氧化羰基化的催化活性

    Institute of Scientific and Technical Information of China (English)

    程庆彦; 梁亚男; 高玲; 王延吉

    2008-01-01

    A novel complex Pd(C4H2O4)(C4H8N2)0.5 has been synthesized by solvent thermal synthesis and used as a heterogeneous catalyst for direct synthesis of diphenyl carbonate (DPC) by oxidative carbonylation of phenol. In the reaction system of Pd(C4H2O4)(C4H8N2)0.5/Cu(OAc)2/ tetrabutylammonium bromide/ hydroquinone/ 4A molecular sieves, the effect of reaction temperature, time and CO pressure on catalytic activity were investigated, and the results revealed that the catalyst could catalyze oxidative carbonylation of phenol effectively. Under suitable reaction conditions of T=90℃, t=4h, p(O2)=0.3 MPa, p(CO)=3.9 MPa and CH2Cl2 as solvent, the turnover number (TON) of diphenyl carbonate can reach about 13.50 (mol-DPC/mol-Pd), which is higher than the TON for pure PdCl2 under the same reaction conditions.

  4. 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.

  5. Degradation of methylene blue by catalytic oxidation in Na2WO4-H2O2 system%钨酸钠-双氧水体系催化氧化降解亚甲基蓝

    Institute of Scientific and Technical Information of China (English)

    高立新; 张大全; 顾茸义

    2011-01-01

    The degradation of methylene blue by catalytic oxidation in Na2WO4-H2O2 system was discussed. The results showed that the degradation rate of methylene blue was near 100% after 40 min of reaction in Na2WO4-H2O2 system. The optimum conditions for 100mL methylene blue ( 10 mg/L ) degradation were as follows: reaction temperature 60 ℃, sodium tungstate ( 0.01 mol/L ) dosage 7.0 mL, 30% H2O2 solution dosage 3.5mL. The degradation of methylene blue was effective in a wide range of pH value ( 1 ~ 14 ). The UV-Vis spectroscopic analyses found that the characteristic absorption peaks originally in 664 nm, 614 nm and 292 nm, 244 nm disappeared, indicating that hazardous organic compounds were transformed into small molecules. Under these conditions, reaction rate constant for methylene blue degradation was 0.0879 min 1, activation energy was 34.61 k J/mol. The degradation of methylene blue in Na2WO4-H2O2 system accorded well with the first-order kinetics model.%研究了钨酸钠.双氧水体系对亚甲基蓝模拟印染废水的催化氧化降解效果.结果表明,当0.01 mol/L的钨酸钠溶液的加入量为7.0 mL、30%的双氧水溶液的加入量为3.5 mL、反应温度60℃.反应40 min后,对100mL浓度为10 mg/L的亚甲基蓝模拟废水的脱色率接近100%.反应在较宽的pH值范围(1~14),都有较好的去除效果.紫外可见光谱分析表明,原水样在664 nm、614 nm和292 am,244nm处的特征吸收波峰消失了,降解为小分子物质.在此条件下的亚甲基蓝降解速率常数为0.0879 min-1,活化能较低,为34.61 kJ/mol.反应符合一级反应动力学模型.

  6. Vibrational spectroscopic study of the natural layered double hydroxide manasseite now defined as hydrotalcite-2H - Mg6Al2(OH)16[CO3]ṡ4H2O

    Science.gov (United States)

    Frost, Ray L.; Scholz, Ricardo; López, Andrés; Theiss, Frederick L.

    2014-01-01

    Raman and thermo-Raman spectroscopy have been applied to study the mineral formerly known as manasseite now simply renamed as hydrotalcite-2H Mg6Al2(OH)16[CO3]ṡ4H2O. The mineral is a member of the homonymous hydrotalcite supergroup. Hydrogen bond distances calculated using a Libowitzky-type empirical function varied between 2.61 and 3.00 Å. Stronger hydrogen bonds were formed by water units as compared to the hydroxyl units. Raman spectroscopy enabled the identification of bands attributed to the hydroxyl units. Two Raman bands at 1059 and 1064 cm-1 are assigned to symmetric stretching modes of the carbonate anion. Thermal treatment shifts these bands to higher wavenumbers indicating a change in the strength of the carbonate bonding.

  7. Vibrational spectroscopic study of the natural layered double hydroxide manasseite now defined as hydrotalcite-2H-Mg6Al2(OH)16[CO3]⋅4H2O.

    Science.gov (United States)

    Frost, Ray L; Scholz, Ricardo; López, Andrés; Theiss, Frederick L

    2014-01-24

    Raman and thermo-Raman spectroscopy have been applied to study the mineral formerly known as manasseite now simply renamed as hydrotalcite-2H Mg6Al2(OH)16[CO3]⋅4H2O. The mineral is a member of the homonymous hydrotalcite supergroup. Hydrogen bond distances calculated using a Libowitzky-type empirical function varied between 2.61 and 3.00Å. Stronger hydrogen bonds were formed by water units as compared to the hydroxyl units. Raman spectroscopy enabled the identification of bands attributed to the hydroxyl units. Two Raman bands at 1059 and 1064 cm(-1) are assigned to symmetric stretching modes of the carbonate anion. Thermal treatment shifts these bands to higher wavenumbers indicating a change in the strength of the carbonate bonding.

  8. 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.

  9. Development of Accurate Chemical Equilibrium Models for Oxalate Species to High Ionic Strength in the System: Na-Ba-Ca-Mn-Sr-Cl-NO3-PO4-SO4-H2O at 25°C

    Energy Technology Data Exchange (ETDEWEB)

    Qafoku, Odeta; Felmy, Andrew R.

    2007-01-01

    The development of an accurate aqueous thermodynamic model is described for oxalate species in the Na-Ba-Ca-Mn-Sr-Cl-NO3-PO4-SO4-H2O system at 25°C. The model is valid to high ionic strength (as high as 10m) and from very acid (10m H2SO4) to neutral and basic conditions. The model is based upon the equations of Pitzer and co-workers. The necessary ion-interaction parameters are determined by comparison with experimental data taken from the literature or determined in this study. The proposed aqueous activity and solubility model is valid for a range of applications from interpretation of studies on mineral dissolution at circumneutral pH to the dissolution of high-level waste tank sludges under acidic conditions.

  10. Study of phase equilibria in the CO(NH2)2-KH2PO4-K2HPO4-H2O system at 25°C using an optimized method of cross sections

    Science.gov (United States)

    Noskov, M. N.; Mazunin, S. A.

    2015-06-01

    Phase equilibria are studied in ternary contouring systems and in the CO(NH2)2-KH2PO4-K2HPO4-H2O quaternary system at 25°C using an optimized method of cross sections. It is found that an incongruent chemical compound forms between the components of a system with the composition 2KH2PO4 · K2HPO4. The compositions of eutonic and peritonic solutions and the solid phases saturating them are determined. The lines of monovariant equilibria and the crystallization surface of potassium dihydrogen phosphate are studied. The location of the eutonic and peritonic solutions and monovariant equilibrium lines near the plane are shown.

  11. 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.

  12. Ferroelectric phase transition in hydrogen-bonded 2-aminopyridine phosphate (NC sub 4 H sub 4 NH sub 2)centre dot H sub 3 PO sub 4

    CERN Document Server

    Czapla, Z; Waskowska, A

    2003-01-01

    A new crystal of 2-aminopyridine phosphate (NC sub 4 H sub 4 NH sub 2)centre dot H sub 3 PO sub 4 has been grown and its x-ray structure and physical properties were studied. At room temperature the crystals are monoclinic, space group C2/c. The flat 2-aminopyridine cations are hydrogen bonded to the anionic [PO sub 4 ] groups. The interesting feature of the crystal structure is the three-dimensional network of hydrogen bonds including, among others, two strong, symmetrical O centre dot centre dot centre dot H, H centre dot centre dot centre dot O interactions with disordered proton locations. Symmetrically related PO sub 4 anions linked through these protons form infinite (PO sub 4) subinfinity chains along the crystal a-axis. The anomalies in the temperature dependence of the electric permittivity showed that the crystal undergoes ferroelectric phase transition at T sub c = 103.5 K. The spontaneous polarization takes place along the crystal a-axis, being parallel to the chains of the hydrogen-bonded PO sub ...

  13. 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

  14. Synthesis and Structural Characterization of a Novel 2D Supramolecular Complex {[Dy2Zn(dinic)4(H2O)8]·H2O}n (H2dinic=2,5-Pyridinedicaboxylic Acid)

    Institute of Scientific and Technical Information of China (English)

    HU De-Xin; XUE Lin; CHE Yun-Xia

    2006-01-01

    A new dysprosium-zinc coordination polymer {[Dy2Zn(dinic)4(H2O)8]·H2O}n 1(H2dinic = 2,5-pyridinedicaboxylic acid) has been synthesized and structurally characterized by X-ray analysis. The complex (C28H30Dy2N4O25Zn, Mr = 1212.94) crystallizes in triclinic, space group P-1 with a = 7.8911(16), b = 9.3177(19), c = 13.029(3)(A), α = 75.29(3), β = 75.04(3), γ =79.00(3)°, V = 887.1(3)(A)3, Z = 1, Dc=2.236 g/cm3,μ(MoKα) = 4.947 mm-1, F(000) = 570, the final R = 0.0345 and wR = 0.0903 for 3644 observed reflections with I> 2σ(I). A two-dimensional supramolecular structure is formed in 1, which was characterized by elemental analysis, IR, TG analysis, and single-crystal X-ray diffraction.

  15. Spectroscopic and magnetic properties of the metastable states in the coordination network [{Co(prm)2}2{Co(H2O)2}{W(CN)8}2]·4H2O (prm = pyrimidine).

    Science.gov (United States)

    Le Bris, Rémy; Tsunobuchi, Yoshihide; Mathonière, Corine; Tokoro, Hiroko; Ohkoshi, Shin-ichi; Ould-Moussa, Nawel; Molnar, Gabor; Bousseksou, Azzedine; Létard, Jean-François

    2012-03-05

    The study of the metastable states, obtained by thermal quenching or by light irradiation in the [{Co(prm)(2)}(2){Co(H(2)O)(2)}{W(CN)(8)}(2)]·4H(2)O complex, is reported using powder X-ray diffraction, Raman spectroscopy, optical reflectivity, and magnetic measurements. This compound is characterized by a electron-transfer (ET) phase transition occurring between a high-temperature phase (HT phase) formed by paramagnetic Co(II)-W(V) units and a low-temperature phase (LT phase) formed by diamagnetic Co(III)-W(IV) units. Metastable phases can be induced at low temperature either by thermal quenching rapidly cooling phase named RC or by irradiation photo-induced phase named PI similar to the well-known Light-Induced Excited Spin State Trapping effect. The relaxation dynamics of the metastable phases have been studied and revealed some differences between the RC and PI phases. The sigmoidal shape of the relaxation curves in the RC phase is in agreement with the cooperative nature of the process. Thermodynamic parameters that govern the relaxation have been determined and used to reproduce the experimental Thermal-Induced Excited Spin State Trapping curve.

  16. 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.

  17. Structure determination of Mg3(OH)5Cl.4H2O (F5 phase) from laboratory powder diffraction data and its impact on the analysis of problematic magnesia floors.

    Science.gov (United States)

    Sugimoto, Kunihisa; Dinnebier, Robert E; Schlecht, Thomas

    2007-12-01

    The crystal structure with the idealized formula Mg(3)(OH)(5)Cl.4H(2)O, the so-called F5 phase according to 5Mg(OH)(2).MgCl(2).8H(2)O in the system MgCl(2)-MgO-H(2)O, has been solved ab initio from high-quality laboratory powder diffraction data at room temperature. The F5 phase is structurally related to 3Mg(OH)(2).MgCl(2).8H(2)O (F3 form). The F5 phase consists of infinite triple chains with one Mg(OH)(6) and two Mg(OH)(4)(OH(2))(2) octahedra as building units intercalated by chlorides, which are partly substituted by disordered hydroxides in the real structure. The F5 phase is of technological importance as the most important binder phase in Sorel cements. Knowledge of the crystal structure enables the full quantitative phase analysis of magnesia cements for the first time, which turns out to be very helpful in the search for possible causes of broken or bleached magnesia floors. Two real-life examples are given.

  18. 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.

  19. [{Cu(phen)2}(mu-malato){Cu(phen)(NO3)}](NO3).4H2O: malate acting as a tetradentate and dibridging ligand in a dinuclear copper complex.

    Science.gov (United States)

    Zhang, Xiang Dong; Sun, Jin Yu; Zhao, Zhen; Ma, Yong Chao; Zhu, Miao Li

    2006-01-01

    The crystal structure of the title compound, mu-2-hydroxybutanedioato-1kappa2O4,O4':2kappa3O1,O2,O4-nitrato-2kappaO-tris(1,10-phenanthroline)-1kappa(4)N,N';2kappa(2)N,N'-dicopper(II) nitrate tetrahydrate, [Cu2(C4H3O5)(NO3)(C12H8N2)3](NO3).4H2O, contains an unsymmetrical dinuclear copper complex with Cu(phen)2 and Cu(phen)(NO3) moieties (phen is 1,10-phenanthroline) bridged by a malate (2-hydroxybutanedioate) ligand, which acts as a double-bridging and tetradentate ligand. As a result of this double-bridging action, especially the direct coordination of the O atom of one carboxylate group of malate to the two Cu atoms, the Cu...Cu distance is only 4.199 (1) Angstrom and the two phen planes are roughly parallel [the shortest interplanar distance is 3.28 (1) Angstrom], exhibiting an obvious intramolecular pi-pi stacking interaction.

  20. Vibrational spectroscopic characterization of the phosphate mineral ludlamite (Fe,Mn,Mg)3(PO4)2ṡ4H2O - A mineral found in lithium bearing pegmatites

    Science.gov (United States)

    Frost, Ray L.; Xi, Yunfei; Scholz, Ricardo; Belotti, Fernanda M.

    2013-02-01

    The objective of this work is to analyze ludlamite (Fe,Mn,Mg)3(PO4)2ṡ4H2O from Boa Vista mine, Galiléia, Brazil and to assess the molecular structure of the mineral. The phosphate mineral ludlamite has been characterized by EMP-WDS, Raman and infrared spectroscopic measurements. The mineral is shown to be a ferrous phosphate with some minor substitution of Mg and Mn. Raman bands at 917 and 950 cm-1 are assigned to the symmetric stretching mode of HOPO32- and PO43- units. Raman bands at 548, 564, 599 and 634 cm-1 are assigned to the ν4PO43- bending modes. Raman bands at 2605, 2730, 2896 and 3190 cm-1 and infrared bands at 2623, 2838, 3136 and 3185 cm-1 are attributed to water stretching vibrations. By using a Libowitzky empirical function, hydrogen bond distances are calculated from the OH stretching wavenumbers. Strong hydrogen bonds in the structure of ludlamite are observed as determined by their hydrogen bond distances. The application of infrared and Raman spectroscopy to the study of ludlamite enables the molecular structure of the pegmatite mineral ludlamite to be assessed.

  1. 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.

  2. 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

  3. Synthesis and Crystal Structure of [Cu(phen)2(SO4)(H2O)]·0.5C4H4O4·7H2O

    Institute of Scientific and Technical Information of China (English)

    WANG Xiao-Qin; WEN Yi-Hang; KANG Yao; ZHANG Jian; CHENG Jian-Kai; LI Zhao-Ji; YAO Yuan-Gen

    2006-01-01

    The title compound, [Cu(phen)2(SO4)(H2O)]·0.5C4H4O4·7H2O (phen = 1,10-phe-nanthroline and C4H4O4 = fumaric acid), has been synthesized and characterized by single-crystal X-ray diffraction. The crystal is of triclinic, space group P with a = 11.4827(2), b = 11.9086(2), c = 13.77350(10)(A), α = 80.6830(10), β = 66.6480(10), γ = 64.0480(10)o, V = 1554.63(4) (A)3, Mr = 722.17, Z = 2, Dc = 1.543 g/cm3, μ = 0.845 mm-1, F(000) = 750, R = 0.0349 and wR = 0.0837 for 4754 observed reflections (I > 2σ(I)). The compound contains a six-coordinated copper(II) center, which is surround by four N atoms of two phen ligands (Cu-N distances in the range of 1.997(2)~2.225(2)(A)), one sulfate O atom (Cu-O = 2.0037(17) (A)) and one water O atom (Cu-O(5w) = 2.719(2) (A)) in a distorted octahedral geometry. Extensive hydrogen-bonding interactions are involved in water molecules, ligated sulfate anions and fumaric acid molecules. In addition, π-π interactions via aromatic nitrogen-containing ligands are also discussed. The combination of non-covalent interactions leads to the formation of a 3-D network structure.

  4. 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.

  5. Utilization of Snail (Achatina fulica Shell Waste for Synthesis of Calcium Tartrate Tetrahydrate (CaC4H4O6.4H2O Single Crystals in Silica Gel

    Directory of Open Access Journals (Sweden)

    Imam Sakdi

    2012-01-01

    Full Text Available Snail (Achatina fulica shell waste is massively produced by many home industries in Indonesia, especially in East Java. The snail shell is known for high calcium; therefore it is potential to be used as calcium source of supernatant in the synthesis of piezoeletric material, such as single crystal of calcium tartrate tetrahydrate (CaTT. The aim of this research is to study the synthesis and characterization of CaTT or CaC4H4O6.4H2O from snail shell waste in silica gel. Supernatant solution of CaCl2 was prepared from CaO, which previously made by calcinating the shell at 1000°C, and then reacted with HCl 1,5M. Synthesis of CaTT was conducted in a single-tube reaction at room temperature in which silica gel was used as growth medium with gelling time of 10 days and growth time of 2 weeks. The pH of gel and CaCl2 concentration were varied, 3.00; 3.50; 4.00; 4.50; 5.00; and 0.27; 0.36; 0.45; 0.54 M respectively, in order to obtain optimum condition of the synthesis, which is indicated from crystal yields. The synthesized crystals were characterized by atomic adsorption spectrophotometry (AAS, infrared spectroscopy (IR and powder X-ray diffraction (XRD. Experimental data shows that optimum condition was obtained at pH of 3.50 and [CaCl2] of 0.45M with yield of 69.37%. The obtained single crystal has clear color and octahedral-like shape with size ranged between 4 – 9 mm. Analysis data by FTIR and powder XRD confirmed that the obtained crystal was CaTT single crystals with crystal system of orthorhombic.

  6. 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.

  7. Synthesis and Crystal Structure of a Novel Amino-acid-containing Polyoxometalate: K6[Cu(Ala)2(H2O)2]2[Cu4(H2O)2(AsW9O34)2]*16H2O%新型氨基酸-钨砷多金属氧酸盐K6[Cu(Ala)2*(H2O)2]2[Cu4(H2O)2(AsW9O34)2]*16H2O的合成与晶体结构

    Institute of Scientific and Technical Information of China (English)

    王永慧; 胡长文; 王恩波; 胡宁海; 贾恒庆; 邢彦

    2001-01-01

    The novel amino-acid-containing polyoxometalate K6[Cu(Ala)2(H2O)2]2[Cu4(H2O)2\\5(AsW9O34)2]*16H2O was synthesized from the rea ction of K10[Cu4(H2O)2(AsW9O34)2]*20H2O with β-alanine. Its structure has been determined by single crystal X-ray diffraction. It crystallizes in the triclinic space group P1, with a=1.196 3(2) nm, b=1.536 5(3) nm, c=1.591 4(3) nm, α=93.97(3)°, β=110.88(3)°, γ=101.07(3)°, V=2.651 8(9) nm3 and Z=1. Least-squares refinement of the structure leads to R and Rw factors of 0.067 3 and 0.162 8, respectively. An unusual structural feature of the compound is that the polyanion [Cu4(H2O)2(AsW9O34)2]10- is linked with the amino-acid complex of Cu2+ by a μ-oxygen atom.

  8. Calculation of multicomponent ionic diffusion from zero to high concentration: I. The system Na-K-Ca-Mg-Cl-SO 4-H 2O at 25°C

    Science.gov (United States)

    Felmy, Andrew R.; Weare, John H.

    1991-01-01

    A model is described for the calculation of diffusion coefficients and other vector transport processes for the six component seawater system Na-K-Ca-Mg-Cl-SO 4-H 2O at 25 °C, from low to high ionic strengths. The model is based upon an extension of the empirical equations of MILLER (1967a) for the calculation of Onsager phenomenological coefficients and upon an accurate thermodynamic model utilizing the ion-interaction method of PITZER (1979) and coworkers. The necessary parameters for the activity derivatives and the Onsager coefficients may be evaluated from binary and ternary data. Additional data are not required for applications in more complex systems. The present model parameterization accurately reproduces all of the relevant, binary mutual diffusion coefficients to high ionic strength. In common-ion ternary systems, the model with the present parameterization does well for solutions in which the concentrations of the component electrolytes are approximately equal and for the dominant electrolyte in systems in which one of the electrolytes is in excess. The model may not be as accurate for the minor components of mixed electrolyte systems, because the required ternary experimental data are not available; however, even in these cases errors do not exceed 20%. The model is also used to calculate diffusion coefficients at the composition of seawater. Our calculated values are supported by the measured conductivities, partial molal conductivities, and mutual diffusion coefficients of neutral components at seawater composition. The importance of coupling between diffusive flows is illustrated by application to a hypothetical geochemical problem which could result from a salt dome penetrating an overlying formation saturated with seawater. The large diffusive flux of NaCl creates significant gradients in all of the minor species (i.e., K +, Ca 2+, Mg 2+, SO 42-), even though there were no initial concentration gradients for these species. The use of tracer

  9. 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.

  10. A Lewis acid catalytic core sandwiched by inorganic polyoxoanion caps: selective H2O2-based oxidations with [Al(III)4(H2O)10(β-XW9O33H)2](6-) (X = As(III), Sb(III)).

    Science.gov (United States)

    Carraro, Mauro; Bassil, Bassem S; Sorarù, Antonio; Berardi, Serena; Suchopar, Andreas; Kortz, Ulrich; Bonchio, Marcella

    2013-09-18

    The Al(III)-containing polyanions [Al(III)4(H2O)10(β-XW9O33H)2](4-) with X = As(III) (1) and Sb(III) (2) feature four aluminum(III) centers sandwiched by two trivacant (β-XW9O33) Keggin units, and trigger peroxide catalysis as well as substrate coordination via multiple Lewis acid site interactions.

  11. New iron(II) spin crossover coordination polymers [Fe(μ-atrz)3]X2·2H2O (X = ClO4¯, BF4¯) and [Fe(μ-atrz)(μ-pyz)(NCS)2]·4H2O with an interesting solvent effect.

    Science.gov (United States)

    Chuang, Yu-Chun; Liu, Chi-Tsun; Sheu, Chou-Fu; Ho, Wei-Lun; Lee, Gene-Hsiang; Wang, Chih-Chieh; Wang, Chih-Cheh; Wang, Yu

    2012-04-16

    A potential bridging triazole-based ligand, atrz (trans-4,4'-azo-1,2,4-triazole), is chosen to serve as building sticks and incorporated with a spin crossover metal center to form a metal organic framework. Coordination polymers of iron(II) with the formula [Fe(μ-atrz)(3)]X(2)·2H(2)O (where X = ClO(4)(-) (1·2H(2)O) and BF(4)(-) (2·2H(2)O)) in a 3D framework and [Fe(μ-atrz)(μ-pyz)(NCS)(2)]·4H(2)O (3·4H(2)O) in a 2D layer structure were synthesized and structurally characterized. The magnetic measurements of 1·2H(2)O and 2·2H(2)O reveal spin transitions near room temperature; that of 3 exhibits an abrupt spin transition at ~200 K with a wide thermal hysteresis, and the spin transition behavior of these polymers are apparently correlated with the water content of the sample. Crystal structures have been determined both at high spin and at low spin states for 1·2H(2)O, 2·2H(2)O, and 3·4H(2)O. Each iron(II) center in 1·2H(2)O and 2·2H(2)O is octahedrally coordinated with six μ-atrz ligands, which in turn links the other Fe center forming a strong three-dimensional (3D) network; counteranion and water molecules are located in the voids of the lattice. The FeN(6) octahedron of 3·4H(2)O is formed with two atrz, two pyrazine (pyz) ligands, and two NCS(-) ligands, where the ligands atrz and pyz are bridged between iron centers forming a 2D layer polymer. A zigzag chain of water molecules is found between the layers, and there is a distinct correlation between the thermal hysteresis with the amount of water molecules the exist in the crystal.

  12. sup 5 sup 9 Co NQR study on superconducting Na sub x CoO sub 2 centre dot yH sub 2 O

    CERN Document Server

    Kobayashi, Y; Sato, M

    2003-01-01

    Layered Co oxide Na sub x CoO sub 2 centre dot yH sub 2 O with a superconducting transition temperature T sub c =4.5 K has been studied by sup 5 sup 9 Co NQR. The nuclear spin relaxation rate 1/ sup 5 sup 9 T sub 1 is nearly proportional to temperature T in the normal state. In the superconducting state, it exhibits the coherence peak and decreases with decreasing T below approx 0.8T sub c. Detailed comparison of the 1/T sub 1 T values and the magnetic susceptibilities between Na sub x CoO sub 2 centre dot yH sub 2 O and Na sub x CoO sub 2 implies that the metallic state of the former system is closer to a ferromagnetic phase than that of the latter. These experimental results impose a restriction on the mechanism of the superconductivity.

  13. O2CC6H4C6H4CO2(SnPh32∙4H2O AND HO2CC6H4C6H4CO2SnBu2Cl: SYNTHESIS AND INFRARED STUDY

    Directory of Open Access Journals (Sweden)

    ABDOU MBAYE

    2015-02-01

    Full Text Available When the diphenic acid HO2CC6H4C6H4CO2H is allowed to react with SnBu2Cl2 or SnPh3OH, HO2CC6H4C6H4CO2. SnBu2Cl (A and O2CC6H4C6H4CO2(SnPh32∙4H2O(B were obtained and characterized by infrared spectroscopy. The structures are an infinite chain or an oligomer, the diphenic anion being a monodentate or a monochelating ligand. The environment around the tin centers is trigonal bipyramidal or octahedral.

  14. Holo- and hemidirected lead(II) in the polymeric [Pb(4)(mu-3,4-TDTA)2(H2O)2]*4H2O complex. N,N,N',N'-tetraacetate ligands derived from o-phenylenediamines as sequestering agents for lead(II).

    Science.gov (United States)

    Sanchiz, Joaquín; Esparza, Pedro; Villagra, Diego; Domínguez, Sixto; Mederos, Alfredo; Brito, Felipe; Araujo, Lorena; Sánchez, Agustin; Arrieta, Juan Manuel

    2002-11-18

    The coordinating ability of the ligands 3,4-toluenediamine-N,N,N',N'-tetraacetate (3,4-TDTA), o-phenylenediamine-N,N,N',N'-tetraacetate (o-PhDTA), and 4-chloro-1,2-phenylenediamine-N,N,N',N'-tetraacetate (4-Cl-o-PhDTA) (H4L acids) toward lead(II) is studied by potentiometry (25 degrees C, I = 0.5 mol x dm(-3) in NaClO4), UV-vis spectrophotometry, and 207Pb NMR spectrometry. The stability constants of the complex species formed were determined. X-ray diffraction structural analysis of the complex [Pb4(mu-3,4-TDTA)4(H2O)2]*4H2O (1) revealed that 1 has a 2-D structure. The layers are built up by the polymerization of centrosymmetric [Pb4L2(H2O)2] tetranuclear units. The neutral layers have the aromatic rings of the ligands pointing to the periphery, whereas the metallic ions are located in the central part of the layers. In compound 1, two types of six-coordinate lead(II) environments are produced. The Pb(1) is coordinated to two nitrogen atoms and four carboxylate oxygens from the ligand, whereas Pb(2) has an O6 trigonally distorted octahedral surrounding. The lead(II) ion is surrounded by five carboxylate oxygens and a water molecule. The carboxylate oxygens belong to four different ligands that are also joined to four other Pb(1) ions. The selective uptake of lead(II) was analyzed by means of chemical speciation diagrams as well as the so-called conditional or effective formation constants K(Pb)eff. The results indicate that, in competition with other ligands that are strong complexing agents for lead(II), our ligands are better sequestering agents in acidic media.

  15. 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.

  16. 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.

  17. 新型超分子化合物[ Co( L-alanato)2(phen) ]NO3·4H2O的水热合成及其晶体结构%Hydrothermal Synthesis of Novel Supramolecular Complex [ Co(L-alanato) 2 (phen) ] NO3 · 4H2O and Its Crystal Structure

    Institute of Scientific and Technical Information of China (English)

    冯秀玲; 张玉平

    2011-01-01

    A novel supramolecular complex, [Co(L-alanato)2(phen) ]NO3 ? 4H2O(1) , was synthesized by the hydrothennal reaction of Co(NO3)2 ? 6H2O with L-alanine and 1,10-phenanthroline (phen). The structure was characterized by IR, elemental analysis and single crystal X-ray diffraction analysis. 1 belongs to triclinic system, space group P-\\ with a = 10.121 9(5) A, 6 =11.461 1 (12) A, c = 12.573 2(12) A, a =71. 13(3)°, β = 67.52(3)°, γ =66.08(3)°, V = 1207.24 (18) A3, Dc = 1.511 g ? cm-3, Z = 2, F(000) =572, Mr = 549.38, μ =0.777 mm-1, R1 = 0.083 6, wR2 =0.214 2. 1 exhibited a metabolic octahedral structure by a six-coordinated of central atom Co( Ⅲ) with one phen and two alanine ligands. Intermolecular hydrogen bond of 1 constituted three-dimensional structure. The results from thermal analysis showed that 1 in tum lost crystal water and 1,10-phenanthroline during heating.%以Co( NO3)2.6H2O,邻菲罗啉(phen)与L-丙氨酸(L-alanine)为原料,通过水热法合成了新型超分子化合物[ Co(L-alanato)2(phen)] NO3.4H2O(1),其结构经IR,元素分析和X-射线单晶衍射分析表征.1属三斜晶系,空间群P-1,晶胞参数a=10.121 9(5)(A),b=11.461 1(12)(A),c=12.573 2(12)(A),α=71.13(3)°,β=67.52(3)°,γ=66.08(3)°,V=1 207.24(18)(A)3,Dc=1.511 g.cm-3,Z=2,F(000) =572,Mr =549.38,μ=0.777mm-1,R1 =0.083 6,ωR2=0.2142.1的中心原子Co(Ⅲ)形成六配位的变形八面体结构,并通过氢键形成三维结构.热分析研究表明,1在加热过程中先后失去结晶水和邻菲啰啉.

  18. 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.

  19. 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.

  20. 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.

  1. Structure Characterizations and Electrochemical Property of Hexa(imidazole)iron(Ⅱ) Chloride Water Solvate:[Fe(Im)6]Cl2·4H2O%氯化六咪唑合铁四水分子的结构表征和电化学性能研究

    Institute of Scientific and Technical Information of China (English)

    建方方; 汪庆祥; 孙萍萍; 焦奎

    2004-01-01

    The crystal structure of the title compound, [Fe(Im)6]Cl2·4H2O, (Im=imidazole) was determined by X-ray analysis. The crystal structure consists of Fe(Im)62+ cation, two Cl- anions and four non-coordinated water molecules. It crystallizes in the triclinic system, space group PI, with lattice parameters a=0.879 7(2) nm, b=0.906 8(2) nm, c=1.058 1(2) nm, a=75.35(3)°, β=83.20(3)°, γ=61.85(3)°, and Z=1; The Fe(Ⅱ) ion assumes centrosymmetric octahedron geometry with the FeN6 core. Six imidazole molecules are coordinated to each iron(Ⅱ) ion through its tertiary nitrogen atom. The bond distances of Fe-N are in range of 0.212 8(1) nm to 0.220 4(1) nm. In the solid state, [Fe(Im)6]2+, H2O molecules and chlorine anions form three dimensional hydrogen bonds network which stabilized the crystal structure. Elemental analysis and electronic spectrum are in agreement with the structural data. The thermal gravity (TG) data indicate that thermal decomposition of the title compound takes place in five steps. In these cases, the residue may be Fe. From the cyclic voltammogram measurement in EtOH/H2O, we know that electrode reaction was a quasi-reversible process. CCDC: 215335.

  2. 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.

  3. 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.

  4. 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.

  5. 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.

  6. 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.

  7. 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.

  8. 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.

  9. A study of the x-irradiated Cs sub 5 H sub 3 (SO sub 4) sub 4 centre dot H sub 2 O crystal by EPR in the 80-415 K temperature range

    CERN Document Server

    Waplak, S; Baranov, A I; Shuvalov, L A

    1997-01-01

    The EPR spectra of the x-irradiated fast proton conductor Cs sub 5 H sub 3 (SO sub 4) sub 4 centre dot H sub 2 O were investigated in the temperature range of 80-415 K. Two kinds of paramagnetic SO sub 4 sup - centres with different proton configurations below about 370 K and freeze-out behaviour of one of them below about 200 K were observed. The role of acid proton dynamics with respect to the glassy-like transition is discussed. (author)

  10. 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 ...

  11. 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)

  12. A family of new glutarate compounds: synthesis, crystal structures of: Co(H2O)5L(1), Na2[CoL2] (2), Na2[L(H2L)4/2] (3), {[Co3(H2O)6L2](HL)2}.4H2O (4), {[Co3(H2O)6L2](HL)2}.10H2O (5), {[Co3(H2O)6L2]L2/2}.4H2O (6), and Na2{[Co3(H2O)2]L8/2].6H2O (7), and magnetic properties of 1 and 2 with H2L = HOOC-(CH2)3-COOH.

    Science.gov (United States)

    Zheng, Yue-Qing; Lin, Jian-Li; Xu, Wei; Xie, Hong-Zhen; Sun, Jie; Wang, Xian-Wen

    2008-11-17

    Seven new glutaric acid complexes, Co(H 2O) 5L 1, Na 2[CoL 2] 2, Na 2[L(H 2L) 4/2] 3, {[Co 3(H 2O) 6L 2](HL) 2}.4H 2O 4, {[Co 3(H 2O) 6L 2](HL) 2}.10H 2O 5, {[Co 3(H 2O) 6L 2]L 2/2}.4H 2O 6, and Na 2{[Co 3(H 2O) 2]L 8/2].6H 2O 7 were obtained and characterized by single-crystal X-ray diffraction methods along with elemental analyses, IR spectroscopic and magnetic measurements (for 1 and 2). The [Co(H 2O) 5L] complex molecules in 1 are assembled into a three-dimensional supramolecular architecture based on intermolecular hydrogen bonds. Compound 2 consists of the Na (+) cations and the necklace-like glutarato doubly bridged [ C o L 4 / 2 ] 2 - infinity 1 anionic chains, and 3 is composed of the Na (+) cations and the anionic hydrogen bonded ladder-like [ L ( H 2 L ) 4 / 2 ] 2 - infinity 1 anionic chains. The trinuclear {[Co 3(H 2O) 6L 2](HL) 2} complex molecules with edge-shared linear trioctahedral [Co 3(H 2O) 6L 2] (2+) cluster cores in 4 and 5 are hydrogen bonded into two-dimensional (2D) networks. The edge-shared linear trioctahedral [Co 3(H 2O) 6L 2] (2+) cluster cores in 6 are bridged by glutarato ligands to generate one-dimensional (1D) chains, which are then assembled via interchain hydrogen bonds into 2D supramolecular networks. The corner-shared linear [Co 3O 16] trioctahedra in 7 are quaternate bridged by glutarato ligands to form 1D band-like anionic {[Co 3(H 2O) 2]L 8/2} (2+) chains, which are assembled via interchain hydrogen bonds into 2D layers, and between them are sandwiched the Na (+) cations. The magnetic behaviors of 1 and 2 obey the Curie-Weiss law with chi m = C/( T - Theta) with the Curie constant C = 3.012(8) cm (3) x mol (-1) x K and the Weiss constant Theta = -9.4(7) K for 1, as well as C = 2.40(1) cm (3) x mol (-1) x K and Theta = -2.10(5) K for 2, indicating weak antiferromagnetic interactions between the Co(II) ions.

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

    Energy Technology Data Exchange (ETDEWEB)

    Nakra Mohajer, Soukaina; El Harouny, El Hassan [Laboratoire de Physique de la Matière Condensée, Département de Physique, Faculté des Sciences, Université Abdelmalek Essaadi, B.P. 2121 M’Hannech II, 93030 Tétouan (Morocco); Ibral, Asmaa [Equipe d’Optique et Electronique du Solide, Département de Physique, Faculté des Sciences, Université Chouaïb Doukkali, B. P. 20 El Jadida Principale, El Jadida (Morocco); Laboratoire d’Instrumentation, Mesure et Contrôle, Département de Physique, Faculté des Sciences, Université Chouaïb Doukkali, B. P. 20 El Jadida Principale, El Jadida (Morocco); El Khamkhami, Jamal [Laboratoire de Physique de la Matière Condensée, Département de Physique, Faculté des Sciences, Université Abdelmalek Essaadi, B.P. 2121 M’Hannech II, 93030 Tétouan (Morocco); and others

    2016-09-15

    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.

  14. Orientation of the water moiety in CF4-H2O

    Science.gov (United States)

    Evangelisti, Luca; Feng, Gang; Gou, Qian; Guidetti, Gloria; Caminati, Walther

    2012-12-01

    The rotational spectrum of CF4-H217O has been investigated by pulsed jet Fourier transform microwave spectroscopy. A symmetric top effective rotational spectrum has been observed, similarly to the case of the parent species (W. Caminati, A. Maris, A. Dell'Erba, P.G. Favero, Angew. Chem. Int. Ed. 45 (2006) 6711). The experimental value of the 17O χaa quadrupole coupling constant, 0.54(1) MHz, allows to determine the average value of the angle between the C2 axis of H2O and the C⋯O line, β = 24°.

  15. 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...

  16. 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.

  17. Non-Isothermal Decomposion Kinetics of Supermolecule Compound [Eu(C10H9N2O4)(C10H8N2O4)(H2O)3]2·phen·4H2O

    Institute of Scientific and Technical Information of China (English)

    YANG, Rui; HE, Shui-Yang; WU, Wang-Ting; CHEN, Feng-Ying; HU, Rong-Zu

    2006-01-01

    Europium(Ⅲ) compound with 2-oxopropionic acid salicyloyl hydrazone (C10H10N2O4, H3L) and 1,10-phenanthroline (C12HsN2, phen) has been prepared. A yellow prismatic crystal of the compound was obtained, and the molecule crystallized in the triclinic space group P-1. There are two 9-coordinated complex molecules in every structure unit, where every Eu atom is coordinated by three water molecules and two tridentate C10H10N2O4 ligands,forming two stable pentacycles. The coordination polyhedron around Eu3+ was described as a single cap square antiprism. In the crystal cell, there are one free 1,10-phenanthroline and four water molecules. The thermal decomposition of the compound and its kinetics were studied by non-isothermal thermogravimetry. The Kissinger's method and Ozawa's method were used to calculate the activation energy value of the first-step decomposition. The stages of the decompositions were identified by TG-DTG-DSC curve. The non-isothermal kinetic data were analyzed by means of integral and differential methods. The possible reaction mechanism and the kinetic equations were investigated by comparing the kinetic parameters.

  18. Regenerative Fuel Cells for Space Power and Energy Conversion (NaBH4/H2O2 Fuel Cell Development)

    Science.gov (United States)

    Valdez, Thomas I.; Miley, George H.; Luo, Nie; Burton, Rodney; Mather, Joseph; Hawkins, Glenn; Byrd, Ethan; Gu, Lifeng; Shrestha, Prajakti Joshi

    2006-01-01

    A viewgraph presentation describing hydrogen peroxide and sodium borohydride development is shown. The topics include: 1) Motivation; 2) The Sodium Borohydride Fuel Cell; 3) Fuel Cell Comparisons; 4) MEA Optimization; 5) 500-Watt Stack Testing; 6) System Modeling: Fuel Cell Power Source for Lunar Rovers; and 7) Conclusions

  19. Na4(H2O)8[SiMo12O40]•6H2O

    Science.gov (United States)

    Villars, P.; Cenzual, K.; Gladyshevskii, R.; Shcherban, O.; Dubenskyy, V.; Kuprysyuk, V.; Savysyuk, I.; Zaremba, R.

    This document is part of Subvolume A11 'Structure Types. Part 11: Space Groups (135) P42/mbc - (123) P4/mmm' of Volume 43 'Crystal Structures of Inorganic Compounds' of Landolt-Börnstein - Group III 'Condensed Matter'.

  20. Modeling the performance of an ideal NaBH4-H2O2 direct borohydride fuel cell

    Science.gov (United States)

    Stroman, Richard O.; Jackson, Gregory S.

    2014-02-01

    A 2D direct borohydride fuel cell (DBFC) model has been developed to explore the prospective performance of this technology, for a cell with fast selective electrocatalysts and a selective membrane. In the modeled DBFC, a Nafion membrane in the Na+ form separates flow channels with aqueous fuel (0.1-0.5 M NaBH4/4 M NaOH) and oxidizer (4 M H2O2/4 M H2SO4). Electrochemical reactions occur on catalyst-coated channel walls. The electrocatalysts are selective for complete BH4- oxidation and H2O2 reduction, the reactions have fast forward rate constants, and only Na+ and H2O cross the membrane. The model captures interfacial charge transfer reactions and complex transport in the flow channels and membrane. Results show that current density and voltage efficiency vary by >50% from inlet to outlet due to concentration boundary layer development. The BH4- concentration boundary layer limits peak power density, despite migration and fuel utilizations below 10%. Power density increases with BH4- inlet concentration and fuel flow rate, but at the expense of lower fuel utilization. Water crosses the membrane up to 14 times its production rate at the anode. Low fuel utilization and water imbalance suggest the importance of system designs with reactant recirculation and water recovery.

  1. 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...

  2. 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...... of quantum dots, however, results in a large inhomogeneous broadening of quantum dot spectra. Work on self-assembled InGaAs/GaAs quantum dots will be presented. Properties of atom-like single-dot states are investigated optically using high spatial and spectral resolution. Single-dot spectra can be used...

  3. 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...... of quantum dots, however, results in a large inhomogeneous broadening of quantum dot spectra.Work on self-assembled InGaAs/GaAs quantum dots will be presented. Properties of atom-like single-dots states are investigated optically using high spatial and spectral resolution. Single-dot spectra can be used...

  4. Probing individual quantum dots: noise in self-assembled systems.

    Science.gov (United States)

    Vicaro, K O; Gutiérrez, H R; Seabra, A C; Schulz, P A; Cotta, M A

    2009-11-01

    In this work we explore the noise characteristics in lithographically-defined two terminal devices containing self-assembled InAs/InP quantum dots. The experimental ensemble of InAs dots show random telegraph noise (RTN) with tuneable relative amplitude-up to 150%-in well defined temperature and source-drain applied voltage ranges. Our numerical simulation indicates that the RTN signature correlates with a very low number of quantum dots acting as effective charge storage centres in the structure for a given applied voltage. The modulation in relative amplitude variation can thus be associated to the altered electrostatic potential profile around such centres and enhanced carrier scattering provided by a charged dot.

  5. Connecting dots

    DEFF Research Database (Denmark)

    Murakami, Kyoko; Jacobs, Rachel L.

    2017-01-01

    of connecting the dots of recalled moments of individual family members lives and is geared towards building a family’s shared future for posterity. Lastly, we consider a wider implication of family reminiscence in terms of human development. http://www.infoagepub.com/products/Memory-Practices-and-Learning...... and Middleton, 1995). A reminiscence conversation is a dynamic talk-in-interaction, which can produce valuable learning experience for the participants involved. Reminiscence talk contains rich, personal, historic data that can reveal and inform family members of an unknown past. In this seminar/chapter, we...... shall present a discursive approach, a methodology that captures the dynamics of reminiscence. We analyse collected conversational data of British family members reminiscing on their past as a joint family activity. Through such talk-in-interaction, the family members develop continuity within...

  6. 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....

  7. 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.

  8. 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

  9. 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 and organi......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...... their performance....

  10. Town Centre Redevelopment Strategies

    DEFF Research Database (Denmark)

    Vagnby, Bo Hellisen

    After many years of urban growth Danish downtowns are facing some important choices. Shall the stake one-sidedly be on the town centres as driving forces for growth and 'city marketing', or do they still have a role to play in a broader socio-economic context? In the paper we look back on eight...... during late years, where increased internationalisation is in focus and where it seems as if the social dimension of the town centre planning is slipping out of the hands of the urban planners....

  11. From DOT to Dotty

    CERN Document Server

    CERN. Geneva

    2017-01-01

    - Module types are interfaces, which can be abstracted. In this talk Martin will present DOT, a particularly simple calculus that can express systems following these principles. DOT has been developed as the foundation of the next version of Scala. He will also report on dotty, a new Scala compiler that implements the constructs of DOT in its core data structures and that uses the lessons learned to drive Scala’s evolution.

  12. Conditions of stichtite (Mg6Cr2(OH)16[CO3]·4H2O) formation and its geochemical and isotope record of early phanerozoic serpentinizing environments

    Science.gov (United States)

    Melchiorre, Erik B.; Bottrill, Ralph; Huss, Gary R.; Lopez, Amanda

    2017-01-01

    Stichtite is a magnesium-chromium hydroxycarbonate mineral found in association with early Phanerozoic chromite-rich serpentinite rocks of Tasmania, Australia and Tehuitzingo, Mexico. Elemental analysis of stichtite shows a range of compositions within the Cr-Fe-Al hydrotalcite group, with compositional trends associated with each discrete serpentinite host body. Elemental and textural analysis of stichtite-associated chromite indicates that stichtite forms in fore-arc setting rocks through interaction of chromite and methane-rich serpentinizing fluids. The degree to which chromite is replaced by stichtite is inferred to correlate with the length of time that the host rocks spent within the "stichtite window." Carbon stable-isotope analyses of stichtite suggest carbon sourcing from marine kerogen with a minor marine carbonate component in some samples. The carbon and hydrogen stable isotope profile of stichtite ranges from the field of methane from active serpentinizing zones, to organic thermogenic methane. The association of the stichtite 2H polytype (nee barbertonite) with aragonite ± antigorite suggests this is a higher pressure/temperature polytype of stichtite. Reaction completion textures, isotopic values, and qualitative mineral thermobarometric indicators indicate that stichtite forms during serpentinization of fore-arc setting rocks in a methane/H2-rich environment within fluid conduits, ranging from low temperatures and pressures near the surface, to depths where pressure is up to 0.8-1.2 GPa and temperature is up to ∼300 °C. These unique chemical, isotopic, and textural properties of stichtite from distinct serpentinite bodies likely record the duration of serpentinization at specific thermobarometric conditions, and provide a window into the conditions associated with a potentially habitable environment on early Earth and other bodies of the solar system.

  13. 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

  14. Solubility in the ternary system CaSO4 + Na2SO4 + H2O at 298.15 K

    Science.gov (United States)

    Popović, D.; Stupar, G.; Miladinović, J.; Todorović, M.; Zrilić, M.

    2011-12-01

    The solubility in the ternary system, aqueous mixture of CaSO4 and Na2SO4, at T = 298.15 K comprises five different salts: calcium sulfate dihydrate, mirabilite, thenardite, glauberite and labile salt. Using the Extended Pitzer's Ion Interaction model for pure and mixed electrolyte solutions and criteria of phase equilibria, predicted solubility behavior of salts was compared with experimental results from literature. The agreement between calculated and experimental solubilities was excellent in the ionic strength range up to 10.9062 mol kg-1.

  15. 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.

  16. The GSO Data Centre

    CERN Document Server

    Paletou, F; Génot, V; Rouillard, A; Petit, P; Palacios, A; Caux, E; Wakelam, V

    2015-01-01

    Hereafter we describe the activities of the $Grand \\, Sud-Ouest$ Data Centre operated for INSU/CNRS by the OMP-IRAP and the Universit\\'e Paul Sabatier (Toulouse), in a collaboration with the OASU-LAB (Bordeaux) and OREME-LUPM (Montpellier).

  17. 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…

  18. 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.

  19. Observation of the B (s) (0) -> aEuro parts per thousand J/psi I center dot I center dot decay

    NARCIS (Netherlands)

    Aaij, R.; Adeva, B.; Adinolfi, M.; Affolder, A.; Ajaltouni, Z.; Akar, S.; Albrecht, J.; Alessio, F.; Alexander, M.; Ali, S.; Alkhazov, G.; Cartelle, P. Alvarez; Alves, A. A.; Amato, S.; Amerio, S.; Amhis, Y.; An, L.; Anderlini, L.; Andreassi, G.; Andreotti, M.; Andrews, J. E.; Appleby, R. B.; Gutierrez, O. Aquines; Archilli, F.; d'Argent, P.; Artamonov, A.; Artuso, M.; Aslanides, E.; Auriemma, G.; Baalouch, M.; Bachmann, S.; Back, J. J.; Badalov, A.; Baesso, C.; Baldini, W.; Barlow, R. J.; Barschel, C.; Barsuk, S.; Barter, W.; Batozskaya, V.; Battista, V.; Beaucourt, L.; Beddow, J.; Bedeschi, F.; Bediaga, I.; Bel, L. J.; Bellee, V.; Belloli, N.; Belyaev, I.; Ben-Haim, E.; Bencivenni, G.; Benson, S.; Benton, J.; Berezhnoy, A.; Bernet, R.; Bertolin, A.; Bettler, M. -O.; van Beuzekom, M.; Bien, A.; Bifani, S.; Billoir, P.; Bird, T.; Birnkraut, A.; Bizzeti, A.; Blake, T.; Blanc, F.; Blouw, J.; Blusk, S.; Bocci, V.; Bondar, A.; Bondar, N.; Bonivento, W.; Borghi, S.; Borsato, M.; Bowcock, T. J. V.; Bowen, E.; Bozzi, C.; Braun, S.; Britsch, M.; Britton, T.; Brodzicka, J.; Brook, N. H.; Bursche, A.; Buytaert, J.; Cadeddu, S.; Calabrese, R.; Calvi, M.; Calvo Gomez, M.; Campana, P.; Perez, D. Campora; Capriotti, L.; Carbone, A.; Carboni, G.; Cardinale, R.; Cardini, A.; Carniti, P.; Carson, L.; Akiba, K. Carvalho; Casse, G.; Cassina, L.; Garcia, L. Castillo; Cattaneo, M.; Cauet, Ch.; Cavallero, G.; Cenci, R.; Charles, M.; Charpentier, Ph.; Chefdeville, M.; Cheung, S. -F.; Chiapolini, N.; Chrzaszcz, M.; Vidal, X. Cid; Ciezarek, G.; Clarke, P. E. L.; Clemencic, M.; Cliff, H. V.; Closier, J.; Coco, V.; Cogan, J.; Cogneras, E.; Cogoni, V.; Cojocariu, L.; Collazuol, G.; Collins, P.; Comerma-Montells, A.; Contu, A.; Cook, A.; Coombes, M.; Coquereau, S.; Corti, G.; Corvo, M.; Couturier, B.; Cowan, G. A.; Craik, D. C.; Crocombe, A.; Cruz Torres, M.; Cunliffe, S.; Currie, R.; D'Ambrosio, C.; Dall'Occo, E.; Dalseno, J.; David, P. N. Y.; Davis, A.; De Bruyn, K.; De Capua, S.; De Cian, M.; De Miranda, J. M.; De Paula, L.; De Simone, P.; Dean, C. -T.; Decamp, D.; Deckenhoff, M.; Del Buono, L.; Deleage, N.; Demmer, M.; Derkach, D.; Deschamps, O.; Dettori, F.; Dey, B.; Di Canto, A.; Di Ruscio, F.; Donleavy, S.; Dordei, F.; Dorigo, M.; Dosil Suarez, A.; Dossett, D.; Dovbnya, A.; Dreimanis, K.; Dufour, L.; Dujany, G.; Dupertuis, F.; Durante, P.; Dzhelyadin, R.; Dziurda, A.; Dzyuba, A.; Easo, S.; Egede, U.; Egorychev, V.; Eidelman, S.; Eisenhardt, S.; Eitschberger, U.; Ekelhof, R.; Eklund, L.; El Rifai, I.; Elsasser, Ch.; Ely, S.; Esen, S.; Evans, H. M.; Evans, T.; Falabella, A.; Faerber, C.; Farley, N.; Farry, S.; Fay, R.; Ferguson, D.; Fernandez Albor, V.; Ferrari, F.; Ferreira Rodrigues, F.; Ferro-Luzzi, M.; Filippov, S.; Fiore, M.; Fiorini, M.; Firlej, M.; Fitzpatrick, C.; Fiutowski, T.; Fohl, K.; Fol, P.; Fontana, M.; Fontanelli, F.; Forty, R.; Francisco, O.; Frei, C.; Frosini, M.; Furfaro, E.; Gallas Torreira, A.; Galli, D.; Gallorini, S.; Gambetta, S.; Gandelman, M.; Gandini, P.; Garcia Pardinas, J.; Tico, J. Garra; Garrido, L.; Gascon, D.; Gaspar, C.; Gauld, R.; Gavardi, L.; Gazzoni, G.; Geraci, A.; Gerick, D.; Gersabeck, E.; Gersabeck, M.; Gershon, T.; Ghez, Ph.; Gianelle, A.; Giani, S.; Gibson, V.; Girard, O. G.; Giubega, L.; Gligorov, V. V.; Goebel, C.; Golubkov, D.; Golutvin, A.; Gotti, C.; Grabalosa Gandara, M.; Graciani Diaz, R.; Cardoso, L. A. Granado; Grauges, E.; Graverini, E.; Graziani, G.; Grecu, A.; Greening, E.; Gregson, S.; Griffith, P.; Grillo, L.; Gruenberg, O.; Gui, B.; Gushchin, E.; Guz, Yu.; Gys, T.; Hadavizadeh, T.; Hadjivasiliou, C.; Haefeli, G.; Haen, C.; Haines, S. C.; Hall, S.; Hamilton, B.; Hansmann-Menzemer, S.; Harnew, N.; Harnew, S. T.; Harrison, J.; He, J.; Head, T.; Heijne, V.; Hennessy, K.; Henrard, P.; Henry, L.; Hernando Morata, J. A.; van Herwijnen, E.; Hess, M.; Hicheur, A.; Hill, D.; Hoballah, M.; Hombach, C.; Hulsbergen, W.; Humair, T.; Hussain, N.; Hutchcroft, D.; Hynds, D.; Idzik, M.; Ilten, P.; Jacobsson, R.; Jalocha, J.; Jans, E.; Jawahery, A.; Jing, F.; John, M.; Johnson, D.; Jones, C. R.; Joram, C.; Jost, B.; Jurik, N.; Kandybei, S.; Kanso, W.; Karacson, M.; Karbach, T. M.; Karodia, S.; Kelsey, M.; Kenyon, I. R.; Kenzie, M.; Ketel, T.; Khanji, B.; Khurewathanakul, C.; Klaver, S.; Klimaszewski, K.; Kochebina, O.; Kolpin, M.; Komarov, I.; Koppenburg, P.; Kozeiha, M.; Kravchuk, L.; Kreplin, K.; Kreps, M.; Krocker, G.; Krokovny, P.; Krzemien, W.; Kucewicz, W.; Kucharczyk, M.; Kudryavtsev, V.; Kuonen, A. K.; Kurek, K.; Kvaratskheliya, T.; Lacarrere, D.; Lafferty, G.; Lai, A.; Lambert, D.; Lanfranchi, G.; Langenbruch, C.; Langhans, B.; Latham, T.; Lazzeroni, C.; Le Gac, R.; van Leerdam, J.; Lees, J. -P.; Lefevre, R.; Leflat, A.; Lefrancois, J.; Lemos Cid, E.; Leroy, O.; Lesiak, T.

    2016-01-01

    The B (s) (0) -> aEuro parts per thousand J/psi I center dot I center dot decay is observed in pp collision data corresponding to an integrated luminosity of 3 fb(-1) recorded by the LHCb detector at centre-of-mass energies of 7 TeV and 8 TeV. This is the first observation of this decay channel, wit

  20. 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)

  1. 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.

  2. Quantum Dot Solar Cells

    Science.gov (United States)

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

    2002-01-01

    We have been investigating the synthesis of quantum dots of CdSe, CuInS2, and CuInSe2 for use in an intermediate bandgap solar cell. We have prepared a variety of quantum dots using the typical organometallic synthesis routes pioneered by Bawendi, et. al., in the early 1990's. However, unlike previous work in this area we have also utilized single-source precursor molecules in the synthesis process. We will present XRD, TEM, SEM and EDS characterization of our initial attempts at fabricating these quantum dots. Investigation of the size distributions of these nanoparticles via laser light scattering and scanning electron microscopy will be presented. Theoretical estimates on appropriate quantum dot composition, size, and inter-dot spacing along with potential scenarios for solar cell fabrication will be discussed.

  3. 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.

  4. 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....

  5. Study of Tuberculosis cases under RNTCP attending Designated Microscopy Centre at Pravara Rural Hospital, Loni

    Directory of Open Access Journals (Sweden)

    Phalke Deepak Baburao

    2009-12-01

    Full Text Available Pulmonary Tuberculosis is most common form of tuberculosis (TB. The present study was conducted to study the TB cases attending DMC cum DOTS centre at PRH, Loni. It is a retrospective record based study. TB patients information was collected from the record registers at DOTS centre. Out of 611 patients diagnosed, 188 (30% are from the age group 0- 10 years. Extrapulmonary TB patients were more 222(36%. New smear positive TB cases were 196 (32%. Total 61% patients were categorized in CAT- I, 9% in CAT-II & 30% in CAT III. Treatment completion rate was 93.69%. In view of the high success of DOTS strategy, the same is recommended to be continued. For transferred cases, a better system of follow up may be explored for monitoring all these cases.

  6. 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.

  7. 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

  8. A cancer help centre.

    Science.gov (United States)

    Daniel, R

    1996-06-01

    The diagnosis of cancer can be shattering to all involved. The treatment of cancer is intense and often very challenging. Prevailing attitudes to cancer are sometimes fearful, negative and depressing. This combination may leave those affected by cancer shocked, disorientated and without hope. Even worse than this, on asking consultants 'What can I do to help myself?' patients are frequently told 'Absolutely nothing'--crushing in one fell swoop their remaining fighting spirit. Not so in the case of Penny Brohn, who, when faced with the diagnosis of breast cancer, travelled the world to find alternative cancer treatments, and having successfully brought her own cancer under control, dedicated her life to creating a Centre for others wishing to fight their disease.

  9. Stavanger Squash Centre, Norway

    Energy Technology Data Exchange (ETDEWEB)

    Rostvik, H. [Sunlab/ABB, Stavanger (Norway)

    1999-07-01

    Although Stavanger is the technological and financial oil-capital of Norway, the Stavanger Squash Centre was until recently the largest solar building in Norway, with 120 m{sup 2} of collectors. The active, building-integrated, solar air collector in the 45 {sup o} roof facing 15 {sup o} east of due south, has now been delivering solar-heated hot water for the showers for 15 years. The solar system consists of several standard products put together in a new way. Monitoring has shown that the system produced 18,000 kWh/m{sup 2} a (150 kWh/m{sub coll} {sup 2}a). If operated as planned, it could have had a solar contribution of 45,000 kWh/a) (375 kWh/m{sub coll} {sup 2}a), resulting in a 19% solar fraction of total demand. (author)

  10. Call Centre- Computer Telephone Integration

    Directory of Open Access Journals (Sweden)

    Dražen Kovačević

    2012-10-01

    Full Text Available Call centre largely came into being as a result of consumerneeds converging with enabling technology- and by the companiesrecognising the revenue opportunities generated by meetingthose needs thereby increasing customer satisfaction. Regardlessof the specific application or activity of a Call centre, customersatisfaction with the interaction is critical to the revenuegenerated or protected by the Call centre. Physical(v, Call centreset up is a place that includes computer, telephone and supervisorstation. Call centre can be available 24 hours a day - whenthe customer wants to make a purchase, needs information, orsimply wishes to register a complaint.

  11. 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.

  12. Hexagonal graphene quantum dots

    KAUST Repository

    Ghosh, S.

    2016-12-05

    We study hexagonal graphene quantum dots, using density functional theory, to obtain a quantitative description of the electronic properties and their size dependence, considering disk and ring geometries with both armchair and zigzag edges. We show that the electronic properties of quantum dots with armchair edges are more sensitive to structural details than those with zigzag edges. As functions of the inner and outer radii, we find in the case of armchair edges that the size of the band gap follows distinct branches, while in the case of zigzag edges it changes monotonically. This behaviour is further analyzed by studying the ground state wave function and explained in terms of its localisation.

  13. 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

  14. CMCC Data Distribution Centre

    Science.gov (United States)

    Aloisio, Giovanni; Fiore, Sandro; Negro, A.

    2010-05-01

    The CMCC Data Distribution Centre (DDC) is the primary entry point (web gateway) to the CMCC. It is a Data Grid Portal providing a ubiquitous and pervasive way to ease data publishing, climate metadata search, datasets discovery, metadata annotation, data access, data aggregation, sub-setting, etc. The grid portal security model includes the use of HTTPS protocol for secure communication with the client (based on X509v3 certificates that must be loaded into the browser) and secure cookies to establish and maintain user sessions. The CMCC DDC is now in a pre-production phase and it is currently used only by internal users (CMCC researchers and climate scientists). The most important component already available in the CMCC DDC is the Search Engine which allows users to perform, through web interfaces, distributed search and discovery activities by introducing one or more of the following search criteria: horizontal extent (which can be specified by interacting with a geographic map), vertical extent, temporal extent, keywords, topics, creation date, etc. By means of this page the user submits the first step of the query process on the metadata DB, then, she can choose one or more datasets retrieving and displaying the complete XML metadata description (from the browser). This way, the second step of the query process is carried out by accessing to a specific XML document of the metadata DB. Finally, through the web interface, the user can access to and download (partially or totally) the data stored on the storage device accessing to OPeNDAP servers and to other available grid storage interfaces. Requests concerning datasets stored in deep storage will be served asynchronously.

  15. Fuzzy Dot Structure of BG-algebras

    Directory of Open Access Journals (Sweden)

    Tapan Senapati

    2014-09-01

    Full Text Available 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.

  16. 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...

  17. 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

  18. 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

  19. 25 years Nuclear Research Centre

    Energy Technology Data Exchange (ETDEWEB)

    Harde, R.

    1981-07-01

    On June 12, the Karlsruhe Nuclear Research Centre celebrated its 25th anniversary. The Centre was founded on July 19, 1956. The importance of this institution became apparent by the large number of prominent guests, at the head, the Federal President, Karl Carstens. Minister President Spaeth and the Federal Minister for Research and Technology, von Buelow, appreciated the achievements obtained by this big science centre of nuclear technology. The ceremony held in the State theatre of Baden-Wuerttemberg gave testimony of an impressing confession in favour of nuclear energy. Excerpts from the speech of the Chairman of the Managing Board, Prof. Harde, are quoted.

  20. Minister unveils new nanotech centres

    Science.gov (United States)

    Dumé, Belle

    2009-06-01

    Three new nanotechnology research centres are to be set up in France as part of a €70m government plan to help French companies in the sector. Researchers at the new centres, which will be located in Grenoble, Saclay (near Paris) and Toulouse, will be encouraged to collaborate with industry to develop new nanotech-based products. Dubbed NANO-INNOV, the new plan includes €46m for two new buildings at Saclay, with the rest being used to buy new equipment at the three centres and to fund grant proposals from staff to the French National Research Agency (ANR).

  1. The World Heritage Centr

    Directory of Open Access Journals (Sweden)

    Ayman G. Abdel Tawab

    2014-09-01

    Full Text Available New Gourna Village, which is located inside one of the World Heritage Sites in Egypt, has never been recognized as an element contributing to the site’s Outstanding Universal Value. The recognition of the village as a contributing element is reliant on the successful assessment of its authenticity and integrity. Responding to the dramatically declining integrity of the village, the World Heritage Centre has carried out an architectural study to guide the potential conservation works in the property. The study has recommended that a group of objectives and two approaches to the conservation of the village should be adopted. One of these two approaches has been concerned with the conservation of the village according to the architect’s original intentions and principles. The previous approach can be called the principles-based approach. The main aim of this study was to examine the agreement of the World Heritage Centre’s objectives and their proposed principles-based approach to the conservation of the village with the aim to improve its chance in meeting the conditions of authenticity and integrity. The study approached the previous aim by assessing, by means of a proposed methodology; the level of significance, authenticity and integrity of the property. Based on the previous assessment, a list of conservation interventions was proposed to improve the property’s chance in meeting the conditions of authenticity and integrity. Finally, the World Heritage Centre’s recommended approaches and objectives were examined against the previous proposed conservation interventions. The findings indicated the possibility to adopt the principles-based approach to the conservation of New Gourna Village, as well as the other World Heritage Centre’s objectives, without limiting the property’s chance in meeting the conditions of authenticity and integrity. The study recommends to carry out further studies that are concerned with the identification

  2. Measurement of the B (s) (0) -> aEuro parts per thousand I center dot I center dot branching fraction and search for the decay B (0) -> phi phi

    NARCIS (Netherlands)

    Aaij, R.; Adeva, B.; Adinolfi, M.; Affolder, A.; Ajaltouni, Z.; Akar, S.; Albrecht, J.; Alessio, F.; Alexander, M.; Ali, S.; Alkhazov, G.; Cartelle, P. Alvarez; Alves, A. A.; Amato, S.; Amerio, S.; Amhis, Y.; An, L.; Anderlini, L.; Anderson, J.; Andreassi, G.; Andreotti, M.; Andrews, J. E.; Appleby, R. B.; Gutierrez, O. Aquines; Archilli, F.; d'Argent, P.; Artamonov, A.; Artuso, M.; Aslanides, E.; Auriemma, G.; Baalouch, M.; Bachmann, S.; Back, J. J.; Badalov, A.; Baesso, C.; Baldini, W.; Barlow, R. J.; Barschel, C.; Barsuk, S.; Barter, W.; Batozskaya, V.; Battista, V.; Bay, A.; Beaucourt, L.; Beddow, J.; Bedeschi, F.; Bediaga, I.; Bel, L. J.; Bellee, V.; Belloli, N.; Belyaev, I.; Ben-Haim, E.; Bencivenni, G.; Benson, S.; Benton, J.; Berezhnoy, A.; Bernet, R.; Bertolin, A.; Bettler, M-O; van Beuzekom, M.; Bien, A.; Bifani, S.; Billoir, P.; Bird, T.; Birnkraut, A.; Bizzeti, A.; Blake, T.; Blanc, F.; Blouw, J.; Blusk, S.; Bocci, V.; Bondar, A.; Bondar, N.; Bonivento, W.; Borghi, S.; Borsato, M.; Bowcock, T. J. V.; Bowen, E.; Bozzi, C.; Braun, S.; Britsch, M.; Britton, T.; Brodzicka, J.; Brook, N. H.; Buchanan, E.; Bursche, A.; Buytaert, J.; Cadeddu, S.; Calabrese, R.; Calvi, M.; Calvo Gomez, M.; Campana, P.; Perez, D. Campora; Capriotti, L.; Carbone, A.; Carboni, G.; Cardinale, R.; Cardini, A.; Carniti, P.; Carson, L.; Carvalho Akiba, K.; Casse, G.; Cassina, L.; Garcia, L. Castillo; Cattaneo, M.; Cauet, Ch.; Cavallero, G.; Cenci, R.; Charles, M.; Charpentier, Ph.; Chefdeville, M.; Chen, S.; Cheung, S-F; Chiapolini, N.; Chrzaszcz, M.; Vidal, X. Cid; Ciezarek, G.; Clarke, P. E. L.; Clemencic, M.; Cliff, H. V.; Closier, J.; Coco, V.; Cogan, J.; Cogneras, E.; Cogoni, V.; Cojocariu, L.; Collazuol, G.; Collins, P.; Comerma-Montells, A.; Contu, A.; Cook, A.; Coombes, M.; Coquereau, S.; Corti, G.; Corvo, M.; Couturier, B.; Cowan, G. A.; Craik, D. C.; Crocombe, A.; Cruz Torres, M.; Cunliffe, S.; Currie, R.; D'Ambrosio, C.; Dall'Occo, E.; Dalseno, J.; David, P. N. Y.; Davis, A.; De Bruyn, K.; De Capua, S.; De Cian, M.; De Miranda, J. M.; De Paula, L.; De Simone, P.; Dean, C-T; Decamp, D.; Deckenhoff, M.; Del Buono, L.; Deleage, N.; Demmer, M.; Derkach, D.; Deschamps, O.; Dettori, F.; Dey, B.; Di Canto, A.; Di Ruscio, F.; Dijkstra, H.; Donleavy, S.; Dordei, F.; Dorigo, M.; Dosil Suarez, A.; Dossett, D.; Dovbnya, A.; Dreimanis, K.; Dufour, L.; Dujany, G.; Dupertuis, F.; Durante, P.; Dzhelyadin, R.; Dziurda, A.; Dzyuba, A.; Easo, S.; Egede, U.; Egorychev, V.; Eidelman, S.; Eisenhardt, S.; Eitschberger, U.; Ekelhof, R.; Eklund, L.; El Rifai, I.; Elsasser, Ch.; Ely, S.; Esen, S.; Evans, H. M.; Evans, T.; Falabella, A.; Faerber, C.; Farinelli, C.; Farley, N.; Farry, S.; Fay, R.; Ferguson, D.; Fernandez Albor, V.; Ferrari, F.; Ferreira Rodrigues, F.; Ferro-Luzzi, M.; Filippov, S.; Fiore, M.; Fiorini, M.; Firlej, M.; Fitzpatrick, C.; Fiutowski, T.; Fohl, K.; Fol, P.; Fontana, M.; Fontanelli, F.; Forty, R.; Francisco, O.; Frank, M.; Frei, C.; Frosini, M.; Fu, J.; Furfaro, E.; Gallas Torreira, A.; Galli, D.; Gallorini, S.; Gambetta, S.; Gandelman, M.; Gandini, P.; Gao, Y.; Garcia Pardinas, J.; Garra Tico, J.; Garrido, L.; Gascon, D.; Gaspar, C.; Gauld, R.; Gavardi, L.; Gazzoni, G.; Gerick, D.; Gersabeck, E.; Gersabeck, M.; Gershon, T.; Ghez, Ph.; Gianelle, A.; Giani, S.; Gibson, V.; Girard, O. G.; Giubega, L.; Gligorov, V. V.; Goebel, C.; Golubkov, D.; Golutvin, A.; Gomes, A.; Gotti, C.; Gandara, M. Grabalosa; Graciani Diaz, R.; Granado Cardoso, L. A.; Grauges, E.; Graverini, E.; Graziani, G.; Grecu, A.; Greening, E.; Gregson, S.; Griffith, P.; Grillo, L.; Gruenberg, O.; Gui, B.; Gushchin, E.; Guz, Yu.; Gys, T.; Hadavizadeh, T.; Hadjivasiliou, C.; Haefeli, G.; Haen, C.; Haines, S. C.; Hall, S.; Hamilton, B.; Han, X.; Hansmann-Menzemer, S.; Harnew, N.; Harnew, S. T.; Harrison, J.; He, J.; Head, T.; Heijne, V.; Hennessy, K.; Henrard, P.; Henry, L.; Hernando Morata, J. A.; van Herwijnen, E.; Hess, M.; Hicheur, A.; Hill, D.; Hoballah, M.; Hombach, C.; Hulsbergen, W.; Humair, T.; Hussain, N.; Hutchcroft, D.; Hynds, D.; Idzik, M.; Ilten, P.; Jacobsson, R.; Jaeger, A.; Jalocha, J.; Jans, E.; Jawahery, A.; Jing, F.; John, M.; Johnson, D.; Jones, C. R.; Joram, C.; Jost, B.; Jurik, N.; Kandybei, S.; Kanso, W.; Karacson, M.; Karbach, T. M.; Karodia, S.; Kecke, M.; Kelsey, M.; Kenyon, I. R.; Kenzie, M.; Ketel, T.; Khanji, B.; Khurewathanakul, C.; Klaver, S.; Klimaszewski, K.; Kochebina, O.; Kolpin, M.; Komarov, I.; Koopman, R. F.; Koppenburg, P.; Kozeiha, M.; Kravchuk, L.; Kreplin, K.; Kreps, M.; Krocker, G.; Krokovny, P.; Kruse, F.; Krzemien, W.; Kucewicz, W.; Kucharczyk, M.; Kudryavtsev, V.; Kuonen, A. K.; Kurek, K.; Kvaratskheliya, T.; Lacarrere, D.; Lafferty, G.; Lai, A.; Lambert, D.; Lanfranchi, G.; Langenbruch, C.; Latham, T.; Lazzeroni, C.

    2015-01-01

    Using a dataset corresponding to an integrated luminosity of 3.0 fb(-1) collected in pp collisions at centre-of-mass energies of 7 and 8 TeV, the B (s) (0) -> aEuro parts per thousand I center dot I center dot branching fraction is measured to be B(B-0 -> phi phi) = (1.84 +/- 0.05(stat) +/- 0.07 (sy

  3. 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.

  4. 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.

  5. 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.

  6. 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

  7. 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.

  8. 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)

  9. 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.

  10. Person-centred reflective practice.

    Science.gov (United States)

    Devenny, Bob; Duffy, Kathleen

    Person-centred health and person-centred care have gained prominence across the UK following the publication of reports on public inquiries exploring failings in care. Self-awareness and participation in reflective practice are recognised as vital to supporting the person-centred agenda. This article presents an education framework for reflective practice, developed and used in one NHS board in Scotland, and based on the tenets of the clinical pastoral education movement. Providing an insight into the usefulness of a spiritual component in the reflective process, the framework provides an opportunity for nurses and other healthcare professionals to examine the spiritual dimensions of patient encounters, their own values and beliefs, and the effect these may have on their practice.

  11. Construction of the Wigner Data Centre

    CERN Document Server

    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.

  12. Single quantum dot nanowire photodetectors

    NARCIS (Netherlands)

    Van Kouwen, M.P.; Van Weert, M.H.M.; Reimer, M.E.; Akopian, N.; Perinetti, U.; Algra, R.E.; Bakkers, E.P.A.M.; Kouwenhoven, L.P.; Zwiller, V.

    2010-01-01

    We report InP nanowire photodetectors with a single InAsP quantum dot as light absorbing element. With excitation above the InP band gap, the nanowire photodetectors are efficient (quantum efficiency of 4%). Under resonant excitation of the quantum dot, the photocurrent amplitude depends on the line

  13. 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

  14. 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

  15. 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

  16. The CCCB is a cultural centre, not a tourist centre

    Directory of Open Access Journals (Sweden)

    Elena Xirau

    2004-04-01

    Full Text Available Last February, Barcelona's Centre of Contemporary Culture (CCCB celebrated its first ten years in existence. During this time, this institution has looked to be a showcase to the most modern and innovative cultural expressions focused on reflecting on the concept of the city. In this interview, Josep Ramoneda offers his personal view, as the CCCB's director. He talks of how this cultural project was born, of how the concept of the institution took shape in the CCCB, of its relations with Barcelona's Strategic Plan, of how the project has evolved, of the architectural remodelling of the Casa de la Caritat building for its conversion into a cultural centre, of the relations with other institutions and its future.

  17. 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.

  18. European Centre for Disease Prevention and Control.

    Science.gov (United States)

    Evans, Roger

    2014-11-04

    The European Centre for Disease Prevention and Control was set up in 2005 to strengthen Europe's defences against infectious diseases. The centre is an independent agency of the European Union and is based in Stockholm, Sweden.

  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. Hydrophobin-Encapsulated Quantum Dots.

    Science.gov (United States)

    Taniguchi, Shohei; Sandiford, Lydia; Cooper, Maggie; Rosca, Elena V; Ahmad Khanbeigi, Raha; Fairclough, Simon M; Thanou, Maya; Dailey, Lea Ann; Wohlleben, Wendel; von Vacano, Bernhard; de Rosales, Rafael T M; Dobson, Peter J; Owen, Dylan M; Green, Mark

    2016-02-01

    The phase transfer of quantum dots to water is an important aspect of preparing nanomaterials that are suitable for biological applications, and although numerous reports describe ligand exchange, very few describe efficient ligand encapsulation techniques. In this report, we not only report a new method of phase transferring quantum dots (QDs) using an amphiphilic protein (hydrophobin) but also describe the advantages of using a biological molecule with available functional groups and their use in imaging cancer cells in vivo and other imaging applications.

  1. Quantum Dots in Cell Biology

    OpenAIRE

    Barroso, Margarida M.

    2011-01-01

    Quantum dots are semiconductor nanocrystals that have broad excitation spectra, narrow emission spectra, tunable emission peaks, long fluorescence lifetimes, negligible photobleaching, and ability to be conjugated to proteins, making them excellent probes for bioimaging applications. Here the author reviews the advantages and disadvantages of using quantum dots in bioimaging applications, such as single-particle tracking and fluorescence resonance energy transfer, to study receptor-mediated t...

  2. Quantum dots in cell biology.

    Science.gov (United States)

    Barroso, Margarida M

    2011-03-01

    Quantum dots are semiconductor nanocrystals that have broad excitation spectra, narrow emission spectra, tunable emission peaks, long fluorescence lifetimes, negligible photobleaching, and ability to be conjugated to proteins, making them excellent probes for bioimaging applications. Here the author reviews the advantages and disadvantages of using quantum dots in bioimaging applications, such as single-particle tracking and fluorescence resonance energy transfer, to study receptor-mediated transport.

  3. 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.

  4. 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...

  5. 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.

  6. 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.

  7. Neighbourhood Centres – Organisation, Management and Finance

    DEFF Research Database (Denmark)

    Larsen, Jacob Norvig

    public subsidy. Some of the centres have high number of users on a daily basis, whereas others are only rarely used. It is explored how organisation, management and financial set-up differs among the centres. Quantitative data on financial issues and annual accounts of fifteen centres were analysed......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...... to identify different financial models and analyse economic sustainability. As regards organisational and management models data were collected through documentary sources and by means of personal interviews and field visits to ten centres. Even within the analysed limited population of centres economic...

  8. 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.

  9. 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

  10. 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...

  11. Optically active quantum dots

    Science.gov (United States)

    Gerard, Valerie; Govan, Joseph; Loudon, Alexander; Baranov, Alexander V.; Fedorov, Anatoly V.; Gun'ko, Yurii K.

    2015-10-01

    The main goal of our research is to develop new types of technologically important optically active quantum dot (QD) based materials, study their properties and explore their biological applications. For the first time chiral II-VI QDs have been prepared by us using microwave induced heating with the racemic (Rac), D- and L-enantiomeric forms of penicillamine as stabilisers. Circular dichroism (CD) studies of these QDs have shown that D- and L-penicillamine stabilised particles produced mirror image CD spectra, while the particles prepared with a Rac mixture showed only a weak signal. It was also demonstrated that these QDs show very broad emission bands between 400 and 700 nm due to defects or trap states on the surfaces of the nanocrystals. These QDs have demonstrated highly specific chiral recognition of various biological species including aminoacids. The utilisation of chiral stabilisers also allowed the preparation of new water soluble white emitting CdS nano-tetrapods, which demonstrated circular dichroism in the band-edge region of the spectrum. Biological testing of chiral CdS nanotetrapods displayed a chiral bias for an uptake of the D- penicillamine stabilised nano-tetrapods by cancer cells. It is expected that this research will open new horizons in the chemistry of chiral nanomaterials and their application in nanobiotechnology, medicine and optical chemo- and bio-sensing.

  12. Fossil Dot Com

    DEFF Research Database (Denmark)

    2011-01-01

    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...... 2040. Embodiment of the corporate strategy into designs including urban design, bio refineries, offshore wind, sun and electric vehicles will serve as a platform for describing design challenges of the future - A future where society at large becomes the most important stakeholder demanding sustenance....... Management gurus have taught us for the last 20 years that in the end we all are delivering products and services to end users. This may still hold true; however, we now need to learn that we all are nothing but subsidiary companies of the nature....

  13. Powering the Future Data Centre

    DEFF Research Database (Denmark)

    Zhang, Zhe

    2010-01-01

    . Considering the input impendence of fuel cell and super-cap, the small-signal stability of cascaded converter is analyzed. The system small-signal model is rebuilt and controllers for current loop and voltage loop are designed to obtain good transient performance. Through analysis and synthesis......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...... of the characteristics of these two power sources: long warm-up stage and low dynamics for fuel cell, and variable terminal voltage for supercapacitors. The motivation for this project was to find ways which can overcome those limitations to integrate fuel cells and supercapcitors to the system with high efficiency...

  14. Self-assembled quantum dots in a nanowire system for quantum photonics.

    Science.gov (United States)

    Heiss, M; Fontana, Y; Gustafsson, A; Wüst, G; Magen, C; O'Regan, D D; Luo, J W; Ketterer, B; Conesa-Boj, S; Kuhlmann, A V; Houel, J; Russo-Averchi, E; Morante, J R; Cantoni, M; Marzari, N; Arbiol, J; Zunger, A; Warburton, R J; Fontcuberta i Morral, A

    2013-05-01

    Quantum dots embedded within nanowires represent one of the most promising technologies for applications in quantum photonics. Whereas the top-down fabrication of such structures remains a technological challenge, their bottom-up fabrication through self-assembly is a potentially more powerful strategy. However, present approaches often yield quantum dots with large optical linewidths, making reproducibility of their physical properties difficult. We present a versatile quantum-dot-in-nanowire system that reproducibly self-assembles in core-shell GaAs/AlGaAs nanowires. The quantum dots form at the apex of a GaAs/AlGaAs interface, are highly stable, and can be positioned with nanometre precision relative to the nanowire centre. Unusually, their emission is blue-shifted relative to the lowest energy continuum states of the GaAs core. Large-scale electronic structure calculations show that the origin of the optical transitions lies in quantum confinement due to Al-rich barriers. By emitting in the red and self-assembling on silicon substrates, these quantum dots could therefore become building blocks for solid-state lighting devices and third-generation solar cells.

  15. Chiral Graphene Quantum Dots.

    Science.gov (United States)

    Suzuki, Nozomu; Wang, Yichun; Elvati, Paolo; Qu, Zhi-Bei; Kim, Kyoungwon; Jiang, Shuang; Baumeister, Elizabeth; Lee, Jaewook; Yeom, Bongjun; Bahng, Joong Hwan; Lee, Jaebeom; Violi, Angela; Kotov, Nicholas A

    2016-02-23

    Chiral nanostructures from metals and semiconductors attract wide interest as components for polarization-enabled optoelectronic devices. Similarly to other fields of nanotechnology, graphene-based materials can greatly enrich physical and chemical phenomena associated with optical and electronic properties of chiral nanostructures and facilitate their applications in biology as well as other areas. Here, we report that covalent attachment of l/d-cysteine moieties to the edges of graphene quantum dots (GQDs) leads to their helical buckling due to chiral interactions at the "crowded" edges. Circular dichroism (CD) spectra of the GQDs revealed bands at ca. 210-220 and 250-265 nm that changed their signs for different chirality of the cysteine edge ligands. The high-energy chiroptical peaks at 210-220 nm correspond to the hybridized molecular orbitals involving the chiral center of amino acids and atoms of graphene edges. Diverse experimental and modeling data, including density functional theory calculations of CD spectra with probabilistic distribution of GQD isomers, indicate that the band at 250-265 nm originates from the three-dimensional twisting of the graphene sheet and can be attributed to the chiral excitonic transitions. The positive and negative low-energy CD bands correspond to the left and right helicity of GQDs, respectively. Exposure of liver HepG2 cells to L/D-GQDs reveals their general biocompatibility and a noticeable difference in the toxicity of the stereoisomers. Molecular dynamics simulations demonstrated that d-GQDs have a stronger tendency to accumulate within the cellular membrane than L-GQDs. Emergence of nanoscale chirality in GQDs decorated with biomolecules is expected to be a general stereochemical phenomenon for flexible sheets of nanomaterials.

  16. 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....

  17. 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.

  18. Membrane analysis with amphiphilic carbon dots.

    Science.gov (United States)

    Nandi, Sukhendu; Malishev, Ravit; Parambath Kootery, Kaviya; Mirsky, Yelena; Kolusheva, Sofiya; Jelinek, Raz

    2014-09-14

    Newly-synthesized amphiphilic carbon dots were used for spectroscopic analysis and multicolour microscopic imaging of membranes and live cells. We show that Förster resonance energy transfer (FRET) occurred from the amphiphilic carbon dots to different membrane-associated fluorescence acceptors. The amphiphilic carbon dots enabled imaging of membrane disruption by the beta-amyloid peptide.

  19. Criteria of Categorizing Logistics and Distribution Centres

    OpenAIRE

    Darko Babić; Anđelko Šćukanec; Kristijan Rogic

    2011-01-01

    Logistics and distribution centres represent very significant infrastructure elements of the macro-logistic system. The creation of the logistics and distribution centres and their connection into a wide (global) network have resulted in the creation of conditions for an adequate distribution of labour and significant increase in the productivity of all the logistics elements and processes, noting that the logistics and distribution centres in this concept have a superregional significance. ...

  20. 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 develo...... development and environmental sustainability, and further, that technology may not even be the most important feature needed to make them function as such....

  1. 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.

  2. Criteria of Categorizing Logistics and Distribution Centres

    Directory of Open Access Journals (Sweden)

    Darko Babić

    2011-07-01

    Full Text Available Logistics and distribution centres represent very significant infrastructure elements of the macro-logistic system. The creation of the logistics and distribution centres and their connection into a wide (global network have resulted in the creation of conditions for an adequate distribution of labour and significant increase in the productivity of all the logistics elements and processes, noting that the logistics and distribution centres in this concept have a superregional significance. This paper represents the summary (results of the research that was carried out on a large number of logistics and distribution centres with the aim of considering the complexity and the issues related to the logistics and distribution centres and the distribution network, their elements and action of the subsystems according to the following criteria: spatial, technical, technological, and organizational, with the aim of defining the categorisation model of the logistics and distribution centres. The analysis of the selected data collected during the research has resulted in defining of the categorisation model of the logistics and distribution centres which foresees six categories. Each of the foreseen categories has been defined according to the set model by the mentioned traffic, technical and technological, and organisational characteristics and the level of service. This is precisely where the application of the categorisation model of the logistics and distribution centres can be found, which will define the relevant categories of the centres applicable in the creation of effective distribution

  3. Nanoscale quantum-dot supercrystals

    Science.gov (United States)

    Baimuratov, Anvar S.; Turkov, Vadim K.; Rukhlenko, Ivan D.; Baranov, Alexander V.; Fedorov, Anatoly V.

    2013-09-01

    We develop a theory allowing one to calculate the energy spectra and wave functions of collective excitations in twoand three-dimensional quantum-dot supercrystals. We derive analytical expressions for the energy spectra of twodimensional supercrystals with different Bravias lattices, and use them to analyze the possibility of engineering the supercrystals' band structure. We demonstrate that the variation of the supercrystal's parameters (such as the symmetry of the periodic lattice and the properties of the quantum dots or their environment) enables an unprecedented control over its optical properties, thus paving a way towards the development of new nanophotonics materials.

  4. [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%.

  5. Single domain SmCo5@Co exchange-coupled magnets prepared from core/shell Sm[Co(CN)6]·4H2O@GO particles: a novel chemical approach.

    Science.gov (United States)

    Yang, Ce; Jia, Lihui; Wang, Shouguo; Gao, Chen; Shi, Dawei; Hou, Yanglong; Gao, Song

    2013-12-20

    SmCo5 based magnets with smaller size and larger maximum energy product have been long desired in various fields such as renewable energy technology, electronic industry and aerospace science. However, conventional relatively rough synthetic strategies will lead to either diminished magnetic properties or irregular morphology, which hindered their wide applications. In this article, we present a facile chemical approach to prepare 200 nm single domain SmCo5@Co core/shell magnets with coercivity of 20.7 kOe and saturation magnetization of 82 emu/g. We found that the incorporation of GO sheets is responsible for the generation of the unique structure. The single domain SmCo5 core contributes to the large coercivity of the magnets and the exchange-coupled Co shell enhances the magnetization. This method can be further utilized in the synthesis other Sm-Co based exchange-coupled magnets.

  6. Synthesis and Structure of a NovelTetranuclear Erbium( Ⅲ) Complex with α-Alanine [Er4(Hala)6·(μ3-OH)4(H2O)8](ClO4)8·3H2O

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    The title complex was synthesized in an aqueous solution and its crystal structure was determined by X-ray diffraction. The crystal crystallizes in a triclinic system, space group P1 with a=1.306 3(2) nm, b=1.319 4(4) nm, c=1.950 2(4) nm, α=90.597(14)°, β=93.998(11)°, γ=94.093(13)°, V=3.344 1(12) nm3, Z=2, the final R indices are R1=0.065 4, wR2=0.126 2 respectively. The complex contains a novel tetranuclear cluster cation with four Er3+ ions connected by four μ3-OH ions and six bridging carboxyl groups. Each erbium ion is coordinated by three μ3-OH, three carboxylic oxygen atoms from three α-alanine and two oxygen atoms from water molecules, forming a square-antiprismatic coordination polyhedron.

  7. 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.

  8. 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.

  9. 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.

  10. 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.

  11. 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.

  12. 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

  13. 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.

  14. Polymer-coated quantum dots

    NARCIS (Netherlands)

    Tomczak, Nikodem; Liu, Rongrong; Vancso, Julius G.

    2013-01-01

    Quantum Dots (QDs) are semiconductor nanocrystals with distinct photophysical properties finding applications in biology, biosensing, and optoelectronics. Polymeric coatings of QDs are used primarily to provide long-term colloidal stability to QDs dispersed in solutions and also as a source of addit

  15. 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

  16. Nuclear Spins in Quantum Dots

    NARCIS (Netherlands)

    Erlingsson, S.I.

    2003-01-01

    The main theme of this thesis is the hyperfine interaction between the many lattice nuclear spins and electron spins localized in GaAs quantum dots. This interaction is an intrinsic property of the material. Despite the fact that this interaction is rather weak, it can, as shown in this thesis, stro

  17. 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.

  18. 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, di...

  19. 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.

  20. The Press Research Centre, 1956-1976.

    Science.gov (United States)

    Press Research Centre, Krakow (Poland).

    In 1956, the Press Research Centre was established in Cracow, Poland by a group of journalists and publishers, for the purpose of instituting press research that would have practical applications. The aims of the Centre were to conduct studies on the history of the Polish press, the contemporary press, press readership, and editorial techniques.…

  1. 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.

  2. 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)

  3. 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.

  4. Carbon dots as antioxidants and prooxidants.

    Science.gov (United States)

    Christensen, Ingeborg Lie; Sun, Ya-Ping; Juzenas, Petras

    2011-10-01

    In this study we report the effect of classical CdSe/ZnS quantum dots and novel spherical carbon dots on generation of singlet oxygen and other reactive oxygen species (ROS) in aqueous solutions in vitro. Free radicals were initiated either chemically using 2,2'-azodiisobutyramidine dihydrochloride (AAPH) or by radiation with a blue light source emitting 390-470 nm (peak 420 nm). Two reagents, dihydrorhodamine 123 (Dhr123) and singlet oxygen sensor green (SOSG), were used as radical probes. Quantum dots and carbon dots inhibited oxidation of the radical probes under decomposition of AAPH. However, when subjected to the blue light both the quantum dots and carbon dots induced oxidation of Dhr123 to a greater extent than SOSG in water. Generation of singlet oxygen was remarkably enhanced in deuterium oxide solutions while oxidation of Dhr123 remained unchanged. For comparison, traditional photosensitizer protoporphyrin IX mainly induced oxidation of SOSG in water. In conclusion, upon external radiation carbon dots or quantum dots generate reactive oxygen species acting as prooxidants. Carbon dots or quantum dots also scavenge free radicals that are generated chemically by an azo compound. Such dual properties of these nanoparticles can be used for photodynamic and photocatalytic or antioxidant applications.

  5. Probing silicon quantum dots by single-dot techniques

    Science.gov (United States)

    Sychugov, Ilya; Valenta, Jan; Linnros, Jan

    2017-02-01

    Silicon nanocrystals represent an important class of non-toxic, heavy-metal free quantum dots, where the high natural abundance of silicon is an additional advantage. Successful development in mass-fabrication, starting from porous silicon to recent advances in chemical and plasma synthesis, opens up new possibilities for applications in optoelectronics, bio-imaging, photovoltaics, and sensitizing areas. In this review basic physical properties of silicon nanocrystals revealed by photoluminescence spectroscopy, lifetime, intensity trace and electrical measurements on individual nanoparticles are summarized. The fabrication methods developed for accessing single Si nanocrystals are also reviewed. It is concluded that silicon nanocrystals share many of the properties of direct bandgap nanocrystals exhibiting sharp emission lines at low temperatures, on/off blinking, spectral diffusion etc. An analysis of reported results is provided in comparison with theory and with direct bandgap material quantum dots. In addition, the role of passivation and inherent interface/matrix defects is discussed.

  6. Holistic design : learning from the Learning Centre

    Energy Technology Data Exchange (ETDEWEB)

    Simon, C. [Charles Simon Architect and Planner, Eden Mills, ON, (Canada); McKee, C. [Kitchener-Waterloo YMCA Outdoor Services, ON (Canada)

    2004-08-01

    The energy efficiency of several solar technologies currently in operation at the Kitchener-Waterloo YMCA's Environmental Learning Centre was evaluated. The off-grid earth-sheltered building dug into a south-facing slope features a sod roof, and protection from north winds by coniferous tree plantations. Passive solar strategies are evaluated, including average indoor temperatures and lighting requirements in both summer and winter. Also evaluated were the centre's ventilation systems, windows and passive heat recovery ventilators (HRVs), solar collectors, masonry heaters, and photovoltaic panels. The centre's composting toilets and use of the Living Machine{sup TM} were also discussed and details of the centre's building materials were provided. Ten straw-bale cabins are currently under construction at the centre, using passive solar strategies for heating, ventilation and cooling and combination propane fired/solar hot water heaters, straw bale building envelope and wood frame roof. Further suggestions for the centre's potential uses, and an outline of the centre's ongoing priorities were outlined. 4 refs.

  7. 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

  8. 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.

  9. Modelling total energy costs of sports centres

    Energy Technology Data Exchange (ETDEWEB)

    Boussabaine, A.H.; Kirkham, R.J.; Grew, R.J. [Liverpool Univ., School of Architecture and Building Engineering, Liverpool (United Kingdom)

    1999-12-07

    Providing and maintaining safe and comfortable conditions in sport centres raises many issues, particularly cost. The paper gives an overview of the factors associated with sport centre servicing and attempts to highlight the governing factors associated with this, particularly energy costs. A total of 19 sport centres in the City of Liverpool in the UK are investigated, using data elicited from the Liverpool Leisure Services Directorate. The energy operating costs were analysed using statistical methods. Six models were developed to predict total energy costs. Testing and validation results showed a high level of model accuracy. The models would be of use to professionals involved in feasibility studies at the design stage. (Author)

  10. Potential of Natural Ventilation in Shopping Centres

    DEFF Research Database (Denmark)

    Diederichsen, Alice; Friis, Kristina; Brohus, Henrik;

    2008-01-01

    The indoor environmental quality (IEQ) is a fundamental requirement for a well performing shopping centre. This paper contains a pilot study of the potential of using hybrid ventilation (a combination of automatically controlled natural and mechanical ventilation - respectively NV and MV......) in shopping centres with focus on both the achieved IEQ and energy consumptions for air movement. By thermal building simulations it is found that there exists an interesting potential for hybrid ventilation of shopping centres, which can lead to great savings in the electrical energy consumptions...... for ventilation and cooling without compromising IEQ....

  11. New centre for intelligent mining systems

    Energy Technology Data Exchange (ETDEWEB)

    Gibson, W.

    2002-10-01

    A Centre for Intelligent Mining Systems has been opened by the University of Alberta's Computing Science Department, a collaborative effort by the University and Syncrude Canada Ltd. The objective of the new Centre is to apply technologies in the area of artificial intelligence and robotics to the problems of surface mining. The Centre has already attracted attention from other players within the industry and a long-term funding proposal by a consortium that includes Syncrude is in the works. Noranda Inc and Inco Inc have also shown interest.

  12. Planetary Radars Operating Centre PROC

    Science.gov (United States)

    Catallo, C.; Flamini, E.; Seu, R.; Alberti, G.

    2007-12-01

    Planetary exploration by means of radar systems, mainly using Ground Penetrating Radars (GPR) plays an important role in Italy. Numerous scientific international space programs are currently carried out jointly with ESA and NASA by Italian Space Agency, the scientific community and the industry. Three important experiments under Italian leadership ( designed and manufactured by the Italian industry), provided by ASI either as contribution to ESA programs either within a NASA/ASI joint venture framework, are now operating: MARSIS on-board Mars Express, SHARAD on-board Mars Reconnaissance Orbiter and CASSINI Radar on-board Cassini spacecraft. In order to support all the scientific communities, institutional customers and experiment teams operation three Italian dedicated operational centers have been realized, namely SHOC, (Sharad Operating Centre), MOC (Marsis Operating Center) and CASSINI PAD ( Processing Altimetry Data). Each center is dedicated to a single instrument management and control, data processing and distribution. Although they had been conceived to operate autonomously and independently one from each other, synergies and overlaps have been envisaged leading to the suggestion of a unified center, the Planetary Radar Processing Center (PROC). PROC is conceived in order to include the three operational centers, namely SHOC, MOC and CASSINI PAD, either from logistics point of view and from HW/SW capabilities point of view. The Planetary Radar Processing Center shall be conceived as the Italian support facility to the scientific community for on-going and future Italian planetary exploration programs. Therefore, scalability, easy use and management shall be the design drivers. The paper describes how PROC is designed and developed, to allow SHOC, MOC and CASSINI PAD to operate as before, and to offer improved functionalities to increase capabilities, mainly in terms of data exchange, comparison, interpretation and exploitation. Furthermore, in the frame of

  13. Dot-in-Well Quantum-Dot Infrared Photodetectors

    Science.gov (United States)

    Gunapala, Sarath; Bandara, Sumith; Ting, David; Hill, cory; Liu, John; Mumolo, Jason; Chang, Yia Chung

    2008-01-01

    Dot-in-well (DWELL) quantum-dot infrared photodetectors (QDIPs) [DWELL-QDIPs] are subjects of research as potentially superior alternatives to prior QDIPs. Heretofore, there has not existed a reliable method for fabricating quantum dots (QDs) having precise, repeatable dimensions. This lack has constituted an obstacle to the development of uniform, high-performance, wavelength-tailorable QDIPs and of focal-plane arrays (FPAs) of such QDIPs. However, techniques for fabricating quantum-well infrared photodetectors (QWIPs) having multiple-quantum- well (MQW) structures are now well established. In the present research on DWELL-QDIPs, the arts of fabrication of QDs and QWIPs are combined with a view toward overcoming the deficiencies of prior QDIPs. The longer-term goal is to develop focal-plane arrays of radiationhard, highly uniform arrays of QDIPs that would exhibit high performance at wavelengths from 8 to 15 m when operated at temperatures between 150 and 200 K. Increasing quantum efficiency is the key to the development of competitive QDIP-based FPAs. Quantum efficiency can be increased by increasing the density of QDs and by enhancing infrared absorption in QD-containing material. QDIPs demonstrated thus far have consisted, variously, of InAs islands on GaAs or InAs islands in InGaAs/GaAs wells. These QDIPs have exhibited low quantum efficiencies because the numbers of QD layers (and, hence, the areal densities of QDs) have been small typically five layers in each QDIP. The number of QD layers in such a device must be thus limited to prevent the aggregation of strain in the InAs/InGaAs/GaAs non-lattice- matched material system. The approach being followed in the DWELL-QDIP research is to embed In- GaAs QDs in GaAs/AlGaAs multi-quantum- well (MQW) structures (see figure). This material system can accommodate a large number of QD layers without excessive lattice-mismatch strain and the associated degradation of photodetection properties. Hence, this material

  14. 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

  15. Brightness-equalized quantum dots

    Science.gov (United States)

    Lim, Sung Jun; Zahid, Mohammad U.; Le, Phuong; Ma, Liang; Entenberg, David; Harney, Allison S.; Condeelis, John; Smith, Andrew M.

    2015-10-01

    As molecular labels for cells and tissues, fluorescent probes have shaped our understanding of biological structures and processes. However, their capacity for quantitative analysis is limited because photon emission rates from multicolour fluorophores are dissimilar, unstable and often unpredictable, which obscures correlations between measured fluorescence and molecular concentration. Here we introduce a new class of light-emitting quantum dots with tunable and equalized fluorescence brightness across a broad range of colours. The key feature is independent tunability of emission wavelength, extinction coefficient and quantum yield through distinct structural domains in the nanocrystal. Precise tuning eliminates a 100-fold red-to-green brightness mismatch of size-tuned quantum dots at the ensemble and single-particle levels, which substantially improves quantitative imaging accuracy in biological tissue. We anticipate that these materials engineering principles will vastly expand the optical engineering landscape of fluorescent probes, facilitate quantitative multicolour imaging in living tissue and improve colour tuning in light-emitting devices.

  16. Synthesis and applications of carbon dots

    OpenAIRE

    Nolan, Andrew Steven

    2015-01-01

    The use of non-invasive methods to visualise and monitor processes inside living organisms is vital in the understanding and diagnosis of disease. The work in this thesis details the synthesis and applications of a new imaging modality; carbon dots, whose inherent fluorescence and non-toxic nature makes them attractive alternatives to more traditional ‘quantum dots’. In this thesis, different methods of carbon dot synthesis were attempted in order to produce carbon dots of t...

  17. Colloidal quantum dots: synthesis, properties and applications

    Science.gov (United States)

    Brichkin, S. B.; Razumov, V. F.

    2016-12-01

    Key recent results obtained in studies of a new class of luminophores, colloidal quantum dots, are analyzed. Modern methods for the synthesis and post-synthetic treatment of colloidal quantum dots that make it possible to achieve record high quantum yield of luminescence and to modify their characteristics for specific applications are considered. Currently important avenues of research on colloidal quantum dots and the problems in and prospects for their practical applications in various fields are discussed. The bibliography includes 272 references.

  18. Occupational deprivation in an asylum centre:

    DEFF Research Database (Denmark)

    Morville, Anne-Le; Erlandsson, Lena-Karin

    2013-01-01

    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...

  19. 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.

  20. Identity Theft: A Study in Contact Centres

    Science.gov (United States)

    Moir, Iain; Weir, George R. S.

    This paper explores the recent phenomenon of identity theft. In particular, it examines the contact centre environment as a mechanism for this to occur. Through a survey that was conducted amongst forty-five contact centre workers in the Glasgow area we determined that contact centres can and do provide a mechanism for identity theft. Specifically, we found a particularly high incidence of agents who had previously dealt with phone calls that they considered suspicious. Furthermore, there are agents within such environments who have previously been offered money in exchange for customers' details, or who know of fellow workers who received such offers. Lastly, we identify specific practices within contact centres that may contribute to the likelihood of identity theft.

  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. 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.

  3. 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.

  4. Synthetic Developments of Nontoxic Quantum Dots.

    Science.gov (United States)

    Das, Adita; Snee, Preston T

    2016-03-03

    Semiconductor nanocrystals, or quantum dots (QDs), are candidates for biological sensing, photovoltaics, and catalysis due to their unique photophysical properties. The most studied QDs are composed of heavy metals like cadmium and lead. However, this engenders concerns over heavy metal toxicity. To address this issue, numerous studies have explored the development of nontoxic (or more accurately less toxic) quantum dots. In this Review, we select three major classes of nontoxic quantum dots composed of carbon, silicon and Group I-III-VI elements and discuss the myriad of synthetic strategies and surface modification methods to synthesize quantum dots composed of these material systems.

  5. 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.

  6. Random Feature Maps for Dot Product Kernels

    CERN Document Server

    Kar, Purushottam

    2012-01-01

    Approximating non-linear kernels using feature maps has gained a lot of interest in recent years due to applications in reducing training and testing times of SVM classifiers and other kernel based learning algorithms. We extend this line of work and present low distortion embeddings for dot product kernels into linear Euclidean spaces. We base our results on a classical result in harmonic analysis characterizing all dot product kernels and use it to define randomized feature maps into explicit low dimensional Euclidean spaces in which the native dot product provides an approximation to the dot product kernel with high confidence.

  7. 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...

  8. Dissipative tunneling in structures with quantum dots and quantum molecules

    OpenAIRE

    Dahnovsky, Yu. I.; Krevchik, V. D.; Semenov, M. B.; Yamamoto, K.; Zhukovsky, V. Ch.; Aringazin, A. K.; Kudryashov, E. I.; Mayorov, V. G.

    2005-01-01

    The problem of tunneling control in systems "quantum dot - quantum well" (as well as "quantum dot - quantum dot" or quantum molecule) and "quantum dot - bulk contact" is studied as a quantum tunneling with dissipation process in the semiclassical (instanton) approximation. For these systems temperature and correlation between a quantum dot radius and a quantum well width (or another quantum dot radius) are considered to be control parameters. The condition for a single electron blockade is fo...

  9. The Imperial College Thermophysical Properties Data Centre

    Science.gov (United States)

    Angus, S.; Cole, W. A.; Craven, R.; de Reuck, K. M.; Trengove, R. D.; Wakeham, W. A.

    1986-07-01

    The IUPAC Thermodynamic Tables Project Centre in London has at its disposal considerable expertise on the production and utilization of high-accuracy equations of state which represent the thermodynamic properties of substances. For some years they have been content to propagate this information by the traditional method of book production, but the increasing use of the computer in industry for process design has shown that an additional method was needed. The setting up of the IUPAC Transport Properties Project Centre, also at Imperial College, whose products would also be in demand by industry, afforded the occasion for a new look at the problem. The solution has been to set up the Imperial College Thermophysical Properties Data Centre, which embraces the two IUPAC Project Centres, and for it to establish a link with the existing Physical Properties Data Service of the Institution of Chemical Engineers, thus providing for the dissemination of the available information without involving the Centres in problems such as those of marketing and advertising. This paper outlines the activities of the Centres and discusses the problems in bringing their products to the attention of industry in suitable form.

  10. 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.

  11. 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...

  12. 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

  13. 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.

  14. 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.

  15. Optically active quantum-dot molecules.

    Science.gov (United States)

    Shlykov, Alexander I; Baimuratov, Anvar S; Baranov, Alexander V; Fedorov, Anatoly V; Rukhlenko, Ivan D

    2017-02-20

    Chiral molecules made of coupled achiral semiconductor nanocrystals, also known as quantum dots, show great promise for photonic applications owing to their prospective uses as configurable building blocks for optically active structures, materials, and devices. Here we present a simple model of optically active quantum-dot molecules, in which each of the quantum dots is assigned a dipole moment associated with the fundamental interband transition between the size-quantized states of its confined charge carriers. This model is used to analytically calculate the rotatory strengths of optical transitions occurring upon the excitation of chiral dimers, trimers, and tetramers of general configurations. The rotatory strengths of such quantum-dot molecules are found to exceed the typical rotatory strengths of chiral molecules by five to six orders of magnitude. We also study how the optical activity of quantum-dot molecules shows up in their circular dichroism spectra when the energy gap between the molecular states is much smaller than the states' lifetime, and maximize the strengths of the circular dichroism peaks by optimizing orientations of the quantum dots in the molecules. Our analytical results provide clear design guidelines for quantum-dot molecules and can prove useful in engineering optically active quantum-dot supercrystals and photonic devices.

  16. Research on Self-Assembling Quantum Dots.

    Science.gov (United States)

    1995-10-30

    0K. in a second phase of this contract we turned our efforts to the fabrication and studies of self assembled quantum dots . We first demonstrated a...method for producing InAs-GasAs self assembled quantum dots (SAD) using MBE. (AN)

  17. 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.

  18. Quantum Dots Coupled to a Superconductor

    DEFF Research Database (Denmark)

    Jellinggaard, Anders Robert

    are tuned electrostatically. This includes tuning the odd occupation of the dot through a quantum phase transition, where it forms a singlet with excitations in the superconductor. We detail the fabrication of these bottom gated devices, which additionally feature ancillary sensor dots connected...

  19. 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.

  20. 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...... number due to increasing dot size....

  1. Optical studies of capped quantum dots

    NARCIS (Netherlands)

    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

  2. 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

  3. 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...

  4. 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). ...

  5. Coherent control of quantum dots

    DEFF Research Database (Denmark)

    Johansen, Jeppe; Lodahl, Peter; Hvam, Jørn Märcher

    In recent years much effort has been devoted to the use of semiconductor quantum dotsystems as building blocks for solid-state-based quantum logic devices. One importantparameter for such devices is the coherence time, which determines the number ofpossible quantum operations. From earlier...... measurements the coherence time of the selfassembledquantum dots (QDs) has been reported to be limited by the spontaneousemission rate at cryogenic temperatures1.In this project we propose to alter the coherence time of QDs by taking advantage of arecent technique on modifying spontaneous emission rates...

  6. Biocompatible quantum dots for biological applications.

    Science.gov (United States)

    Rosenthal, Sandra J; Chang, Jerry C; Kovtun, Oleg; McBride, James R; Tomlinson, Ian D

    2011-01-28

    Semiconductor quantum dots are quickly becoming a critical diagnostic tool for discerning cellular function at the molecular level. Their high brightness, long-lasting, size-tunable, and narrow luminescence set them apart from conventional fluorescence dyes. Quantum dots are being developed for a variety of biologically oriented applications, including fluorescent assays for drug discovery, disease detection, single protein tracking, and intracellular reporting. This review introduces the science behind quantum dots and describes how they are made biologically compatible. Several applications are also included, illustrating strategies toward target specificity, and are followed by a discussion on the limitations of quantum dot approaches. The article is concluded with a look at the future direction of quantum dots.

  7. Quantum-dot supercrystals for future nanophotonics

    Science.gov (United States)

    Baimuratov, Anvar S.; Rukhlenko, Ivan D.; Turkov, Vadim K.; Baranov, Alexander V.; Fedorov, Anatoly V.

    2013-01-01

    The study of supercrystals made of periodically arranged semiconductor quantum dots is essential for the advancement of emerging nanophotonics technologies. By combining the strong spatial confinement of elementary excitations inside quantum dots and exceptional design flexibility, quantum-dot supercrystals provide broad opportunities for engineering desired optical responses and developing superior light manipulation techniques on the nanoscale. Here we suggest tailoring the energy spectrum and wave functions of the supercrystals' collective excitations through the variation of different structural and material parameters. In particular, by calculating the excitonic spectra of quantum dots assembled in two-dimensional Bravais lattices we demonstrate a wide variety of spectrum transformation scenarios upon alterations in the quantum dot arrangement. This feature offers unprecedented control over the supercrystal's electromagnetic properties and enables the development of new nanophotonics materials and devices.

  8. Effect of different uranium compounds on the properties of U-Pt-Y-Ba-O double-perovskite pinning centres in textured Y-Ba-Cu-O superconductor

    Energy Technology Data Exchange (ETDEWEB)

    Sawh, Ravi-Persad; Weinstein, Roy; Parks, Drew; Gandini, Alberto [Beam Particle Dynamics Laboratories, University of Houston, Houston, TX 77204-5005 (United States); Department of Physics, University of Houston, Houston, TX 77204-5005 (United States); Texas Center for Superconductivity and Advanced Materials, University of Houston, Houston, TX 77204-5005 (United States)

    2005-02-01

    An experiment was performed to test the effect of different uranium compounds on the properties of chemical pinning centres. UO{sub 2}, UO{sub 3}, and UO{sub 4}{center_dot}2H{sub 2}O wereadmixed to Y 123+Pt, and textured. Tests of J{sub c} via measurements of trapped field (B{sub trap}) indicate a clear dependence of B{sub trap} on the U compound admixed to create the pinning centres. In all three cases there is a monotonic increase in B{sub trap} as the mass (M{sub U}) of U is increased. However, the magnitude of the increase in B{sub trap} depends on the admixed U compound. The highest increase in B{sub trap} is measured in samples doped with UO{sub 4}{center_dot}2H{sub 2}O, and the lowest is obtained in samples doped with UO{sub 2}. Microstructure studies indicate that the composition of the U-rich pinning deposits is the same in all three cases, i.e. all are the previously identified (U{sub 0.6}Pt{sub 0.4})Y Ba{sub 2}O{sub 6} compound. The primary difference among the three types of samples is that the size of the U-Pt-Y-Ba-O pinning deposits depends on the admixed U compound. While all are in the nanometre domain, the diameter of these deposits was markedly larger in UO{sub 2} doped samples than in UO{sub 3} doped samples, and smallest in UO{sub 4}{center_dot}2H{sub 2}O doped samples. Because some form of poisoning limits the amount of U that can be added to create pinning centres, to M{sub U} {approx}1 wt%, smaller deposits result in a greater number of pinning centres. We conclude that UO{sub 4}{center_dot}2H{sub 2}O is more effective than either UO{sub 3} or UO{sub 2} in the formation of U-Pt-Y-Ba-O pinning centres because of diminished pinning centre size, and consequent increase in pinning centre density.

  9. 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.)

  10. Blood Compatibility Evaluations of Fluorescent Carbon Dots.

    Science.gov (United States)

    Li, Sha; Guo, Zhong; Zhang, Yi; Xue, Wei; Liu, Zonghua

    2015-09-02

    Because of their unique advantages, fluorescent carbon dots are gaining popularity in various biomedical applications. For these applications, good biosafety is a prerequisite for their use in vivo. Studies have reported the preliminary biocompatibility evaluations of fluorescent carbon dots (mainly cytotoxicity); however, to date, little information is available about their hemocompatibility, which could impede their development from laboratory to bedside. In this work, we evaluated the hemocompatibility of fluorescent carbon dots, which we prepared by hydrothermal carbonization of α-cyclodextrin. The effects of the carbon dots on the structure and function of key blood components were investigated at cellular and molecular levels. In particular, we considered the morphology and lysis of human red blood cells, the structure and conformation of the plasma protein fibrinogen, the complement activation, platelet activation, and in vitro and in vivo blood coagulation. We found that the carbon dots have obvious concentration-dependent effects on the blood components. Overall, concentrations of the fluorescent carbon dots at ≤0.1 mg/mL had few adverse effects on the blood components, but at higher doses, the carbon dots impair the structure and function of the blood components, causing morphological disruptions and lysis of red blood cells, interference in the local microenvironments of fibrinogen, activation of the complement system, and disturbances in the plasma and whole blood coagulation function in vitro. However, the carbon dots tend to activate platelets only at low concentrations. Intravenous administration of the carbon dots at doses up to 50 mg/kg did not impair the blood coagulation function. These results provide valuable information for the clinical application of fluorescent carbon dots.

  11. Peptide dot immunoassay and immunoblotting: electroblotting from aluminum thin-layer chromatography plates and isoelectric focusing gels to activated nitrocellulose

    DEFF Research Database (Denmark)

    Bjerrum, O.J.; Holm, A.; Lauritzen, Edgar;

    1993-01-01

    Peptide dot immunoassay, electroblotting, activated nitrocellulose, dot blot, membranes, peptides and proteins......Peptide dot immunoassay, electroblotting, activated nitrocellulose, dot blot, membranes, peptides and proteins...

  12. 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.

  13. 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...

  14. THE ELUSIVENESS OF LEARNER-CENTRED TEACHING

    Directory of Open Access Journals (Sweden)

    Ervin Kovačević

    2016-03-01

    Full Text Available This research will explore teaching styles of university professors. Teaching style is an umbrella term for teaching decisions made during the entire teaching process – planning, delivery, and evaluation. Contemporary university teachers are advised to adopt the learner-centred teaching style which is assumed to produce remarkable possibilities. In the Fall Semester 2015 fifty-two respondents in different faculties of International University of Sarajevo were surveyed using The Principles of Adult Learning Scale inventory designed by Gary J. Conti. Inventory scores were calculated according to guidelines suggested by the author of the inventory. The scores revealed that majority of respondents strongly supported teacher-centred rather than learner-centred styles of instruction. Scores were analysed on gender lines and across three different faculties, namely: Arts and Social Sciences; Business and Administration; Engineering and Natural Sciences. In all five groups none of the seven teaching style indicators was found to conform with the learner-centred teaching criteria. There was no statistically significant difference between the two genders’ preference for a teaching style. And there was no statistically significant difference between teaching style preference across the three different faculties.The results of this research imply that the learner-centred style of instruction is not frequently implemented. Secondly, the results indicate that the requirements necessary for proper application of the learner-centred teaching style are not easy to meet in current written and unwritten norms. Finally, the results show that traditional teaching styles, which have been preserved in different scientific fields, still predominate in universities.

  15. 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....

  16. Byurakan Astrophysical Observatory as Cultural Centre

    Science.gov (United States)

    Mickaelian, A. M.; Farmanyan, S. V.

    2016-12-01

    NAS RA V. Ambartsumian Byurakan Astrophysical Observatory is presented as a cultural centre for Armenia and the Armenian nation in general. Besides being scientific and educational centre, the Observatory is famous for its unique architectural ensemble, rich botanical garden and world of birds, as well as it is one of the most frequently visited sightseeing of Armenia. In recent years, the Observatory has also taken the initiative of the coordination of the Cultural Astronomy in Armenia and in this field, unites the astronomers, historians, archaeologists, ethnographers, culturologists, literary critics, linguists, art historians and other experts.

  17. 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...

  18. Chiral quantum dot based materials

    Science.gov (United States)

    Govan, Joseph; Loudon, Alexander; Baranov, Alexander V.; Fedorov, Anatoly V.; Gun'ko, Yurii

    2014-05-01

    Recently, the use of stereospecific chiral stabilising molecules has also opened another avenue of interest in the area of quantum dot (QD) research. The main goal of our research is to develop new types of technologically important quantum dot materials containing chiral defects, study their properties and explore their applications. The utilisation of chiral penicillamine stabilisers allowed the preparation of new water soluble white emitting CdS quantum nanostructures which demonstrated circular dichroism in the band-edge region of the spectrum. It was also demonstrated that all three types of QDs (D-, L-, and Rac penicillamine stabilised) show very broad emission bands between 400 and 700 nm due to defects or trap states on the surfaces of the nanocrystals. In this work the chiral CdS based quantum nanostructures have also been doped by copper metal ions and new chiral penicilamine stabilized CuS nanoparticles have been prepared and investigated. It was found that copper doping had a strong effect at low levels in the synthesis of chiral CdS nanostructures. We expect that this research will open new horizons in the chemistry of chiral nanomaterials and their application in biotechnology, sensing and asymmetric synthesis.

  19. [Accreditation criteria and quality standards for Poisons centres: development of a quality management system within the Milan Poisons centre].

    Science.gov (United States)

    Della Puppa, Tiziana; Manfrè, Sergio; Grezzi, Marinella

    2006-01-01

    Poisons centres throughout Italy and Europe vary considerably in terms of their institutions and organisation. The European Association of Poisons Centres and Clinical Toxicologists (EAPCCT) has laid down the activities that a poisons centre must carry out, specifying minimum and maximum standards required. These directions allow an evaluation of the service provided. In 2002 Milan Poisons Centre began a project aiming to introduce concepts and methodology proper of the quality systems within poisons centres' institutional activity. Concluded, the project resulted in the centre's certification and the documentation of its procedures: this may now contribute to help define the status and activity of poisons centres in Italy.

  20. Quantum dots with single-atom precision.

    Science.gov (United States)

    Fölsch, Stefan; Martínez-Blanco, Jesús; Yang, Jianshu; Kanisawa, Kiyoshi; Erwin, Steven C

    2014-07-01

    Quantum dots are often called artificial atoms because, like real atoms, they confine electrons to quantized states with discrete energies. However, although real atoms are identical, most quantum dots comprise hundreds or thousands of atoms, with inevitable variations in size and shape and, consequently, unavoidable variability in their wavefunctions and energies. Electrostatic gates can be used to mitigate these variations by adjusting the electron energy levels, but the more ambitious goal of creating quantum dots with intrinsically digital fidelity by eliminating statistical variations in their size, shape and arrangement remains elusive. We used a scanning tunnelling microscope to create quantum dots with identical, deterministic sizes. By using the lattice of a reconstructed semiconductor surface to fix the position of each atom, we controlled the shape and location of the dots with effectively zero error. This allowed us to construct quantum dot molecules whose coupling has no intrinsic variation but could nonetheless be tuned with arbitrary precision over a wide range. Digital fidelity opens the door to quantum dot architectures free of intrinsic broadening-an important goal for technologies from nanophotonics to quantum information processing as well as for fundamental studies of confined electrons.

  1. [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.

  2. Tensions in human-centred design

    NARCIS (Netherlands)

    Steen, M.G.D.

    2011-01-01

    In human-centred design (HCD), researchers and designers attempt to cooperate with and learn from potential users of the products or services which they are developing. Their goal is to develop products or services that match users' practices, needs and preferences. In this position paper it is argu

  3. Frequency selectivity at very low centre frequencies

    DEFF Research Database (Denmark)

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

    2010-01-01

    -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...

  4. Visiting a science centre: what's on offer?

    Science.gov (United States)

    Russell, Ian

    1990-09-01

    Science centres are a valuable resource, used more frequently by family groups and primary school parties than by secondary schools. The importance of affective learning, involving attitude changes, is stressed. Provided the right approach is used, accompanying adults can help children get the most out of a visit.

  5. Mandibular trauma: a two-centre study

    NARCIS (Netherlands)

    Boffano, P.; Kommers, S.C.; Karagozoglu, K.H.; Gallesio, C.; Forouzanfar, T.

    2015-01-01

    The aims of this study were to assess and compare epidemiological data on mandibular fractures from two European centres and to perform a review of the literature. Between 2001 and 2010, a total of 752 patients with a total of 1167 mandibular fractures were admitted to a hospital in Turin, and 245 p

  6. 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.

  7. Cactus: The Centres of a Triangle

    Science.gov (United States)

    Hyde, Hartley

    2009-01-01

    This is the first of two articles which describe how to use "JavaSketchPad" to explore the centres of a triangle. This introductory exercise is suggested in the GSP "Workshop Guide". Students can use "JavaSketchPad Interactive Geometry" (JSP) at home at no cost. They are likely to impress their parents with their enthusiasm for geometry and all…

  8. Scanning gate microscopy of ultra clean carbon nanotube quantum dots

    OpenAIRE

    Xue, Jiamin; Dhall, Rohan; Cronin, Stephen B.; LeRoy, Brian J.

    2015-01-01

    We perform scanning gate microscopy on individual suspended carbon nanotube quantum dots. The size and position of the quantum dots can be visually identified from the concentric high conductance rings. For the ultra clean devices used in this study, two new effects are clearly identified. Electrostatic screening creates non-overlapping multiple sets of Coulomb rings from a single quantum dot. In double quantum dots, by changing the tip voltage, the interactions between the quantum dots can b...

  9. 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.

  10. 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.

  11. 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.

  12. Quantum dot devices for optical communications

    DEFF Research Database (Denmark)

    Mørk, Jesper

    2005-01-01

    . The main property of semiconductor quantum dots compared to bulk material or even quantum well structures is the discrete nature of the allowed states, which means that inversion of the medium can be obtained for very low electron densities. This has led to the fabrication of quantum dot lasers with record......-low threshold currents and amplifiers with record-high power levels. In this tutorial we will review the basic properties of quantum dots, emphasizing the properties which are important for laser and amplifier applications, as well as devices for all-optical signal processing. The high-speed properties...

  13. Electronic properties of aperiodic quantum dot chains

    Science.gov (United States)

    Korotaev, P. Yu.; Vekilov, Yu. Kh.; Kaputkina, N. E.

    2012-04-01

    The electronic spectral and transport properties of aperiodic quantum dot chains are investigated. The systems with singular continuous energy spectrum are considered: Thue-Morse chain, double-periodic chain, Rudin-Shapiro chain. The influence of electronic energy in quantum dot on the spectral properties, band structure, density of states and spectral resistivity, is discussed. Low resistivity regions correspond to delocalized states and these states could be current states. Also we discuss the magnetic field application as the way to tune electronic energy in quantum dot and to obtain metallic or insulating conducting states of the systems.

  14. Amplification Without Inversion in Semiconductor Quantum Dot

    Science.gov (United States)

    Hajibadali, A.; Abbasian, K.; Rostami, A.

    In this paper, we have realized amplification without inversion (AWI) in quantum dot (QD). A Y-type four-level system of InxGa1-xN quantum dot has been obtained and investigated for AWI. It has been shown that, with proper setting of control fields' amplitude, we can obtain reasonable gain. With proper setting of phase difference of control fields and probe field, we can obtain considerable gain in resonant wavelength. We have designed this system by solving the Schrödinger-Poisson equations for InxGa1-xN quantum dot in GaN substrate, self-consistently.

  15. 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

  16. 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

  17. 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

  18. Quantum dot heterojunction solar cells: the mechanism of device operation and impacts of quantum dot oxidation

    OpenAIRE

    Ihly, Rachelle

    2014-01-01

    This thesis explores the understanding of the chemistry and physics of colloidal quantum dots for practical solar energy photoconversion. Solar cell devices that make use of PbS quantum dots generally rely on constant and unchanged optical properties such that band gap energies remain tuned within the device. The design and development of unique experiments to ascertain mechanisms of optical band gap shifts occurring in PbS quantum dot thin-films exposed to air are discussed. The systematic s...

  19. Tailoring Magnetism in Quantum Dots

    Science.gov (United States)

    Zutic, Igor; Abolfath, Ramin; Hawrylak, Pawel

    2007-03-01

    We study magnetism in magnetically doped quantum dots as a function of particle numbers, temperature, confining potential, and the strength of Coulomb interaction screening. We show that magnetism can be tailored by controlling the electron-electron Coulomb interaction, even without changing the number of particles. The interplay of strong Coulomb interactions and quantum confinement leads to enhanced inhomogeneous magnetization which persists at substantially higher temperatures than in the non-interacting case or in the bulk-like dilute magnetic semiconductors. We predict a series of electronic spin transitions which arise from the competition between the many-body gap and magnetic thermal fluctuations. Cond-mat/0612489. [1] R. Abolfath, P. Hawrylak, I. Zuti'c, preprint.

  20. 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...

  1. 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...

  2. 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.

  3. 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

  4. 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.

  5. 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.

  6. Start Shift of Individual Quantum Dots

    Science.gov (United States)

    1999-06-18

    We will here describe the results of the influence of electric field on InP quantum dots embedded in GalnP, lattice matched to GaAs. Experimental...details The sample we used was grown by metal-organic vapour phase epitaxy, and contained InP quantum dots in GanP, lattice matched to GaAs (n-type

  7. Exciton in type-II quantum dot

    Energy Technology Data Exchange (ETDEWEB)

    Sierra-Ortega, J; Escorcia, R A [Universidad del Magdalena, A. A. 731, Santa Marta (Colombia); Mikhailov, I D, E-mail: jsierraortega@gmail.co [Universidad Industrial de Santander, A. A. 678, Bucaramanga (Colombia)

    2009-05-01

    We study the quantum-size effect and the influence of the external magnetic field on the exciton ground state energy in the type-II InP quantum disk, lens and pyramid deposited on a wetting layer and embedded in a GaInP matrix. We show that the charge distribution over and below quantum dot and wetting layer induced by trapped exciton strongly depends on the quantum dot morphology and the strength of the magnetic field.

  8. Random Feature Maps for Dot Product Kernels

    OpenAIRE

    Kar, Purushottam; Karnick, Harish

    2012-01-01

    Approximating non-linear kernels using feature maps has gained a lot of interest in recent years due to applications in reducing training and testing times of SVM classifiers and other kernel based learning algorithms. We extend this line of work and present low distortion embeddings for dot product kernels into linear Euclidean spaces. We base our results on a classical result in harmonic analysis characterizing all dot product kernels and use it to define randomized feature maps into explic...

  9. Chaotic quantum dots with strongly correlated electrons

    OpenAIRE

    Shankar, R.

    2007-01-01

    Quantum dots pose a problem where one must confront three obstacles: randomness, interactions and finite size. Yet it is this confluence that allows one to make some theoretical advances by invoking three theoretical tools: Random Matrix theory (RMT), the Renormalization Group (RG) and the 1/N expansion. Here the reader is introduced to these techniques and shown how they may be combined to answer a set of questions pertaining to quantum dots

  10. 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.

  11. 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.

  12. 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

  13. 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 coo....... The Annual Report for 2001 represents therefore the first report from a period in which the new facilitieshave been utilized to full advantage....... 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...

  14. Patient-centred Prevention among PAD Patients

    DEFF Research Database (Denmark)

    Pii, Kathrine Hoffmann

    2014-01-01

    Intro: This paper discusses a central professional dilemma in patient-centred education: on one hand the concern for ensuring patients autonomy and right to make their own decisions regarding their treatment and, on the other hand, a concern for getting patients to make the “right” decisions......-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...... of a patient-centred prevention programme aimed at PAD patients, which includes medical treatment as well as individual nurse-led lifestyle-oriented conversations (inspired by psychological theory and methods such as Motivational Interviewing). Method: The findings are based on four months ethnographic field...

  15. 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.

  16. Institutional profile: the London Centre for Nanotechnology.

    Science.gov (United States)

    Weston, David; Bontoux, Thierry

    2009-12-01

    Located in the London neighborhoods of Bloomsbury and South Kensington, the London Centre for Nanotechnology is a UK-based multidisciplinary research center that operates at the forefront of science and technology. It is a joint venture between two of the world's leading institutions, UCL and Imperial College London, uniting their strong capabilities in the disciplines that underpin nanotechnology: engineering, the physical sciences and biomedicine. The London Centre for Nanotechnology has a unique operating model that accesses and focuses the combined skills of the Departments of Chemistry, Physics, Materials, Medicine, Electrical and Electronic Engineering, Mechanical Engineering, Chemical Engineering, Biochemical Engineering and Earth Sciences across the two universities. It aims to provide the nanoscience and nanotechnology required to solve major problems in healthcare, information processing, energy and the environment.

  17. Emergency Centre Organization and Automated Triage System

    CERN Document Server

    Golding, Dan; Marwala, Tshilidzi

    2008-01-01

    The excessive rate of patients arriving at accident and emergency centres is a major problem facing South African hospitals. Patients are prioritized for medical care through a triage process. Manual systems allow for inconsistency and error. This paper proposes a novel system to automate accident and emergency centre triage and uses this triage score along with an artificial intelligence estimate of patient-doctor time to optimize the queue order. A fuzzy inference system is employed to triage patients and a similar system estimates the time but adapts continuously through fuzzy Q-learning. The optimal queue order is found using a novel procedure based on genetic algorithms. These components are integrated in a simple graphical user interface. Live tests could not be performed but simulations reveal that the average waiting time can be reduced by 48 minutes and priority is given to urgent patients

  18. Achieving competences in patient-centred care

    DEFF Research Database (Denmark)

    Lomborg, Kirsten; Nielsen, Else Skånning; Jensen, Annesofie Lunde

    2011-01-01

    Aim: To document the efficacy of a training programme in patient-centred care in which the nursing staff was trained to involve chronic obstructive pulmonary patients in assisted personal body care (APBC). The objectives were to describe the programme and uncover the outcomes. Background: Chronic...... obstructive pulmonary patients suffer from breathlessness and may need comprehensive assistance with personal body care. The patients’ wellbeing may be improved and their integrity safeguarded if nurses are able to involve the patients in accordance with their illness conditions and personal preferences....... The training was time-consuming. Conclusion: A comprehensive training programme can improve nursing competences to action patient-centred and involve severely ill respiratory patients in APBC. Further studies are needed to investigate the efficacy from the patients’ perspective. Relevance to clinical practice...

  19. 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&...

  20. [The development process of colon cancer centres].

    Science.gov (United States)

    Sahm, M; Wesselmann, S; Kube, R; Schöffel, N; Pross, M; Lippert, H; Kahl, S

    2013-02-01

    Colon carcinomas are the most common malignant tumours in the Western world. Important findings about the overall quality of medical care have been reported in multi-centre observational studies. A quality enhancement of therapeutic care can be achieved by an additional increase in diagnostic and therapeutic measures in the interdisciplinary setting. The development of colon cancer centres improves the chance to objectively observe the results of medical care induced by the development of an interdisciplinary and cross-sectoral unit that includes a comprehensive medical care for patients. The implementation of the current medical findings based on evidence in clinical routine, the inspection of the usage of guidelines by external specialists as part of an audit and the continuous correction of analysed deficits in the course of treatment guarantee a continuous improvement of service.

  1. Birth of a science centre. Italian phenomenology

    Directory of Open Access Journals (Sweden)

    Paola Rodari

    2006-06-01

    Full Text Available In May 2004 the Balì Museum, Planetarium and interactive science museum, was opened to the public in Italy: 35 hands-on exhibits designed according to the interactive tradition of the Exploratorium in San Francisco, an astronomic observatory for educational activities, a Planetarium with 70 places. With a total investment of about three million euros, about two thirds of which were spent on restructuring the splendid eighteenth-century villa in which it is housed, the undertaking may be considered a small one in comparison with other European science centres. Three million euros: perhaps enough to cover the cost of only the splendid circular access ramp to the brand-new Cosmocaixa in Barcelona, an investment of one hundred million euros. But the interesting aspect of the story of the Balì Museum (but also of other Italian stories, as we shall see lies in the fact that this lively and advanced science centre stands in the bucolic region of the Marches, next to a small town of only 800 inhabitants (Saltara, in the Province of Pesaro and Urbino, in a municipal territory that has a total of 5000. Whereas in Italy the projects for science centres comparable with the Catalan one, for example projects for Rome and Turin, never get off the ground, smaller ones are opening in small and medium-sized towns: why is this? And what does the unusual location of the centres entail for science communication in Italy? This Focus does not claim to tell the whole truth about Italian interactive museums, but it does offer some phenomenological cues to open a debate on the cultural, economic and political premises that favour their lives.

  2. 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.

  3. 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.

  4. 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.

  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. Bismuth centred magnetic perovskite: A projected multiferroic

    Energy Technology Data Exchange (ETDEWEB)

    Kundu, Asish K., E-mail: asish.k@gmail.com [Discipline of Physics, Indian Institute of Information Technology, Design and Manufacturing, Dumna Airport Road, Jabalpur 482005 (India); Seikh, Md. Motin [Department of Chemistry, Visva-Bharati University, Santiniketan, West Bengal 731235 (India); Nautiyal, Pranjal [Discipline of Mechanical Engineering, Indian Institute of Information Technology, Design and Manufacturing, Dumna Airport Road, Jabalpur 482005 (India)

    2015-03-15

    In recent time substantial attention has been initiated to understand the physics behind multiferroism and to design new multiferroic materials. BiMnO{sub 3} and BiFeO{sub 3} are the well-studied Bi-centred multiferroic oxides. BiMnO{sub 3} is a ferromagnetic–ferroelectric (metastable) phase and require drastic conditions to synthesize. However, lanthanum substituted BiMnO{sub 3} phases stabilized at ambient pressure. It is thus of major importance to increase the number of ferromagnetic perovskites with Bi cations that could be designed under ambient conditions. In this article, we have presented an up to date report of investigations on Bi-centred magnetic perovskites, a prospective material for multiferroic application. Central focus is concentrated on La{sub 0.5}Bi{sub 0.5}MnO{sub 3} perovskite with various substitutions at different levels. A few of these perovskites are found to be of practical importance e.g. La{sub 0.5}Bi{sub 0.5}Mn{sub 0.67}Co{sub 0.33}O{sub 3} with high dielectric permittivity coupled with ferromagnetism. A comprehensive analysis of different physical functionalities and their interrelation for a wide range of compositions of these Bi-centred perovskites is presented. It has been found that the complex magnetic behaviour originates from mixed valence metal ions. The ferroelectricity is associated with the 6s{sup 2} lone pair of Bi{sup 3+} cations. The magnetic ground state influences the dielectric properties reflecting the multiferroism in a single material. - Highlights: • Multiferroics have attracted increasing attention due to their possible device applications. • Bismuth centred magnetic perovskite is one kind of such promising multiferroic materials. • Ferromagnetic Bi-perovskites, which are synthesized at ambient conditions, have been discussed.

  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. Bismuth centred magnetic perovskite: A projected multiferroic

    Science.gov (United States)

    Kundu, Asish K.; Seikh, Md. Motin; Nautiyal, Pranjal

    2015-03-01

    In recent time substantial attention has been initiated to understand the physics behind multiferroism and to design new multiferroic materials. BiMnO3 and BiFeO3 are the well-studied Bi-centred multiferroic oxides. BiMnO3 is a ferromagnetic-ferroelectric (metastable) phase and require drastic conditions to synthesize. However, lanthanum substituted BiMnO3 phases stabilized at ambient pressure. It is thus of major importance to increase the number of ferromagnetic perovskites with Bi cations that could be designed under ambient conditions. In this article, we have presented an up to date report of investigations on Bi-centred magnetic perovskites, a prospective material for multiferroic application. Central focus is concentrated on La0.5Bi0.5MnO3 perovskite with various substitutions at different levels. A few of these perovskites are found to be of practical importance e.g. La0.5Bi0.5Mn0.67Co0.33O3 with high dielectric permittivity coupled with ferromagnetism. A comprehensive analysis of different physical functionalities and their interrelation for a wide range of compositions of these Bi-centred perovskites is presented. It has been found that the complex magnetic behaviour originates from mixed valence metal ions. The ferroelectricity is associated with the 6s2 lone pair of Bi3+ cations. The magnetic ground state influences the dielectric properties reflecting the multiferroism in a single material.

  9. Energy Efficiency Improvements Using DC in Data Centres

    OpenAIRE

    Bergqvist, Sofia

    2011-01-01

    The installed power usage in a data centre will often amount to several megawatts (MW). Thetotal power consumption of the data centres in the world is comparable to that of the airtraffic. The high energy costs and carbon dioxide emissions resulting from the operation of adata centre call for alternative, more efficient, solutions for the power supply design. Oneproposed solution to decrease the energy usage is to use a direct current power supply (DCUPS) for all the servers in the data centr...

  10. Optimal catchment area and primary PCI centre volume revisited

    DEFF Research Database (Denmark)

    Schoos, Mikkel Malby; Pedersen, Frants; Holmvang, Lene;

    2015-01-01

    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...

  11. 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...

  12. Advancements in the Field of Quantum Dots

    Science.gov (United States)

    Mishra, Sambeet; Tripathy, Pratyasha; Sinha, Swami Prasad.

    2012-08-01

    Quantum dots are defined as very small semiconductor crystals of size varying from nanometer scale to a few micron i.e. so small that they are considered dimensionless and are capable of showing many chemical properties by virtue of which they tend to be lead at one minute and gold at the second minute.Quantum dots house the electrons just the way the electrons would have been present in an atom, by applying a voltage. And therefore they are very judiciously given the name of being called as the artificial atoms. This application of voltage may also lead to the modification of the chemical nature of the material anytime it is desired, resulting in lead at one minute to gold at the other minute. But this method is quite beyond our reach. A quantum dot is basically a semiconductor of very tiny size and this special phenomenon of quantum dot, causes the band of energies to change into discrete energy levels. Band gaps and the related energy depend on the relationship between the size of the crystal and the exciton radius. The height and energy between different energy levels varies inversely with the size of the quantum dot. The smaller the quantum dot, the higher is the energy possessed by it.There are many applications of the quantum dots e.g. they are very wisely applied to:Light emitting diodes: LEDs eg. White LEDs, Photovoltaic devices: solar cells, Memory elements, Biology : =biosensors, imaging, Lasers, Quantum computation, Flat-panel displays, Photodetectors, Life sciences and so on and so forth.The nanometer sized particles are able to display any chosen colour in the entire ultraviolet visible spectrum through a small change in their size or composition.

  13. 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.

  14. Quantum dots as biophotonics tools.

    Science.gov (United States)

    Cesar, Carlos L

    2014-01-01

    This chapter provides a short review of quantum dots (QDs) physics, applications, and perspectives. The main advantage of QDs over bulk semiconductors is the fact that the size became a control parameter to tailor the optical properties of new materials. Size changes the confinement energy which alters the optical properties of the material, such as absorption, refractive index, and emission bands. Therefore, by using QDs one can make several kinds of optical devices. One of these devices transforms electrons into photons to apply them as active optical components in illumination and displays. Other devices enable the transformation of photons into electrons to produce QDs solar cells or photodetectors. At the biomedical interface, the application of QDs, which is the most important aspect in this book, is based on fluorescence, which essentially transforms photons into photons of different wavelengths. This chapter introduces important parameters for QDs' biophotonic applications such as photostability, excitation and emission profiles, and quantum efficiency. We also present the perspectives for the use of QDs in fluorescence lifetime imaging (FLIM) and Förster resonance energy transfer (FRET), so useful in modern microscopy, and how to take advantage of the usually unwanted blinking effect to perform super-resolution microscopy.

  15. Electromechanical transition in quantum dots

    Science.gov (United States)

    Micchi, G.; Avriller, R.; Pistolesi, F.

    2016-09-01

    The strong coupling between electronic transport in a single-level quantum dot and a capacitively coupled nanomechanical oscillator may lead to a transition towards a mechanically bistable and blocked-current state. Its observation is at reach in carbon-nanotube state-of-art experiments. In a recent publication [Phys. Rev. Lett. 115, 206802 (2015), 10.1103/PhysRevLett.115.206802] we have shown that this transition is characterized by pronounced signatures on the oscillator mechanical properties: the susceptibility, the displacement fluctuation spectrum, and the ring-down time. These properties are extracted from transport measurements, however the relation between the mechanical quantities and the electronic signal is not always straightforward. Moreover the dependence of the same quantities on temperature, bias or gate voltage, and external dissipation has not been studied. The purpose of this paper is to fill this gap and provide a detailed description of the transition. Specifically we find (i) the relation between the current-noise and the displacement spectrum; (ii) the peculiar behavior of the gate-voltage dependence of these spectra at the transition; (iii) the robustness of the transition towards the effect of external fluctuations and dissipation.

  16. Quantum dots for terahertz generation

    Energy Technology Data Exchange (ETDEWEB)

    Liu, H C; Aslan, B; Gupta, J A; Wasilewski, Z R; Aers, G C; SpringThorpe, A J; Buchanan, M [Institute for Microstructural Sciences, National Research Council, Ottawa, K1A 0R6 (Canada)], E-mail: h.c.liu@nrc.ca

    2008-09-24

    Nanostructures made of semiconductors, such as quantum wells and quantum dots (QD), are well known, and some have been incorporated in practical devices. Here we focus on novel structures made of QDs and related devices for terahertz (THz) generation. Their potential advantages, such as low threshold current density, high characteristic temperature, increased differential gain, etc, make QDs promising candidates for light emitting applications in the THz region. Our idea of using resonant tunneling through QDs is presented, and initial results on devices consisting of self-assembled InAs QDs in an undoped GaAs matrix, with a design incorporating a GaInNAs/GaAs short period superlattice, are discussed. Moreover, shallow impurities are also being explored for possible THz emission: the idea is based on the tunneling through bound states of individual donor or acceptor impurities in the quantum well. Initial results on devices having an AlGaAs/GaAs double-barrier resonant tunneling structure are discussed.

  17. 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.

  18. Low energy use at Vaestervik sports centre

    Energy Technology Data Exchange (ETDEWEB)

    2009-05-15

    Vaestervik, in south Sweden, has saved both energy and money since modern energy efficiency equipment was installed in its swimming pool and bowling alley. Energy use in the sports centre has so far fallen by around 830 MWh/year, and operating costs have been reduced by efficient heat recovery. Energy efficiency at the Vaestervik sports centre is a good example of how a local authority can save energy and money by installing modern equipment for ventilation and heat recovery in a facility with high energy consumption. The well-used sports centre, including a swimming pool and bowling alley, is in central Vaestervik. In 1999 the Municipality received grants from the local investment programme (LIP) to improve the facility's energy efficiency. An efficient ventilation system with a dehumidifier and heat exchanger was installed at the swimming pool, reducing the need to introduce cold air. In addition the bowling alley, which did not have heat recovery, was given a modern heat-recovery plant. - Lower operating costs due to efficient heat recovery. - Reduced energy use (electricity and district heating) for the plant at around 830 MWh/year. The modern and highly efficient units for heat recovery, dehumidification and heat exchange result in lower operating costs and reduced energy use, which means that the Municipality of Vaestervik saves energy and money. Installation at the swimming pool resulted in slightly higher air humidity, but a relative humidity of 60% is common in swimming pools and difficult to reduce without inconveniencing bathers. A new fan room installed in the roof contributed to higher than anticipated costs, but the financial and economic gains outweigh these. New frequency-controlled circulation pumps for the pool water were installed in 2007. They are to have occupancy control capability, giving a further improvement of energy saving and heat recovery

  19. 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.

  20. Biological Inspiration in Human Centred Robotics

    Institute of Scientific and Technical Information of China (English)

    HU Huo-sheng; LIU Jin-dong; Calderon Carlos A

    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.

  1. Dynamics of B cells in germinal centres.

    Science.gov (United States)

    De Silva, Nilushi S; Klein, Ulf

    2015-03-01

    Humoral immunity depends on the germinal centre (GC) reaction during which somatically mutated high-affinity memory B cells and plasma cells are generated. Recent studies have uncovered crucial cues that are required for the formation and the maintenance of GCs and for the selection of high-affinity antibody mutants. In addition, it is now clear that these events are promoted by the dynamic movements of cells within and between GCs. These findings have resolved the complexities of the GC reaction in greater detail than ever before. This Review focuses on these recent advances and discusses their implications for the establishment of humoral immunity.

  2. 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....

  3. LUMINESCENCE OF CADMIUM SULFIDE QUANTUM DOTS IN FLUOROPHOSPHATE GLASSES

    OpenAIRE

    Z. O. Lipatova; E. V. Kolobkova; V. A. Aseev

    2015-01-01

    Cadmium sulfide quantum dots are perspective materials in optics, medicine, biology and optoelectronics. Fluorophosphate glasses, doped with cadmium sulfide quantum dots, were examined in the paper. Heat treatment led to the formation of quantum dots with diameters equal to 2.8 nm, 3.0 nm and 3.8 nm. In view of such changes in the quantum dots size the fundamental absorption edge shift and the luminescence band are being displaced to the long wavelengths. Luminescence lifetime has been fou...

  4. 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....

  5. Quantum Dots and Their Multimodal Applications: A Review

    OpenAIRE

    Holloway, Paul H; Teng-Kuan Tseng; Lei Qian; Debasis Bera

    2010-01-01

    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 ...

  6. 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.

  7. 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.

  8. 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

  9. Evidence for curvilinear interpolation from dot alignment judgements

    NARCIS (Netherlands)

    van Assen, MA; Vos, PG

    1999-01-01

    Visual interpolation between dots responsible for rectilinear versus curvilinear contour interpretation was examined with the psychophysical forced directional response (FDR) paradigm. Regular four-dot polygon segments, together with a target dot, were presented to the subjects for 150 ms. Subjects

  10. Toward structurally defined carbon dots as ultracompact fluorescent probes.

    Science.gov (United States)

    LeCroy, Gregory Ethan; Sonkar, Sumit Kumar; Yang, Fan; Veca, L Monica; Wang, Ping; Tackett, Kenneth N; Yu, Jing-Jiang; Vasile, Eugeniu; Qian, Haijun; Liu, Yamin; Luo, Pengju George; Sun, Ya-Ping

    2014-05-27

    There has been much discussion on the need to develop fluorescent quantum dots (QDs) as ultracompact probes, with overall size profiles comparable to those of the genetically encoded fluorescent tags. In the use of conventional semiconductor QDs for such a purpose, the beautifully displayed dependence of fluorescence color on the particle diameter becomes a limitation. More recently, carbon dots have emerged as a new platform of QD-like fluorescent nanomaterials. The optical absorption and fluorescence emissions in carbon dots are not bandgap in origin, different from those in conventional semiconductor QDs. The absence of any theoretically defined fluorescence color-dot size relationships in carbon dots may actually be exploited as a unique advantage in the size reduction toward having carbon dots serve as ultracompact QD-like fluorescence probes. Here we report on carbon dots of less than 5 nm in the overall dot diameter with the use of 2,2'-(ethylenedioxy)bis(ethylamine) (EDA) molecules for the carbon particle surface passivation. The EDA-carbon dots were found to be brightly fluorescent, especially over the spectral range of green fluorescent protein. These aqueous soluble smaller carbon dots also enabled more quantitative characterizations, including the use of solution-phase NMR techniques, and the results suggested that the dot structures were relatively simple and better-defined. The potential for these smaller carbon dots to serve as fluorescence probes of overall sizes comparable to those of fluorescent proteins is discussed.

  11. Coupling of single quantum dots to a photonic crystal waveguide

    DEFF Research Database (Denmark)

    Lund-Hansen, Toke; Stobbe, Søren; Julsgaard, Brian;

    . 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...

  12. 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.``

  13. 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.

  14. 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.

  15. Angiogenic Profiling of Synthesized Carbon Quantum Dots.

    Science.gov (United States)

    Shereema, R M; Sruthi, T V; Kumar, V B Sameer; Rao, T P; Shankar, S Sharath

    2015-10-20

    A simple method was employed for the synthesis of green luminescent carbon quantum dots (CQDs) from styrene soot. The CQDs were characterized by transmission electron microscopy, X-ray photoelectron spectroscopy, Fourier transform infrared, and Raman spectroscopy. The prepared carbon quantum dots did not show cellular toxicity and could successfully be used for labeling cells. We also evaluated the effects of carbon quantum dots on the process of angiogenesis. Results of a chorioallantoic membrane (CAM) assay revealed the significant decrease in the density of branched vessels after their treatment with CQDs. Further application of CQDs significantly downregulated the expression levels of pro-angiogenic growth factors like VEGF and FGF. Expression of VEGFR2 and levels of hemoglobin were also significantly lower in CAMs treated with CQDs, indicating that the CQDs inhibit angiogenesis. Data presented here also show that CQDs can selectively target cancer cells and therefore hold potential in the field of cancer therapy.

  16. 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....

  17. 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.

  18. 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...

  19. 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...

  20. 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.

  1. Glowing graphene quantum dots and carbon dots: properties, syntheses, and biological applications.

    Science.gov (United States)

    Zheng, Xin Ting; Ananthanarayanan, Arundithi; Luo, Kathy Qian; Chen, Peng

    2015-04-08

    The emerging graphene quantum dots (GQDs) and carbon dots (C-dots) have gained tremendous attention for their enormous potentials for biomedical applications, owing to their unique and tunable photoluminescence properties, exceptional physicochemical properties, high photostability, biocompatibility, and small size. This article aims to update the latest results in this rapidly evolving field and to provide critical insights to inspire more exciting developments. We comparatively review the properties and synthesis methods of these carbon nanodots and place emphasis on their biological (both fundamental and theranostic) applications.

  2. 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.

  3. 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

  4. Polymers in Carbon Dots: A Review

    Directory of Open Access Journals (Sweden)

    Yiqun Zhou

    2017-02-01

    Full Text Available Carbon dots (CDs have been widely studied since their discovery in 2004 as a green substitute of the traditional quantum dots due to their excellent photoluminescence (PL and high biocompatibility. Meanwhile, polymers have increasingly become an important component for both synthesis and modification of CDs to provide polymeric matrix and enhance their PL property. Furthermore, critical analysis of composites of CDs and polymers has not been available. Herein, in this review, we summarized the use of polymers in the synthesis and functionalization of CDs, and the applications of these CDs in various fields.

  5. Bilayer graphene quantum dot defined by topgates

    Energy Technology Data Exchange (ETDEWEB)

    Müller, André; Kaestner, Bernd; Hohls, Frank; Weimann, Thomas; Pierz, Klaus; Schumacher, Hans W., E-mail: hans.w.schumacher@ptb.de [Physikalisch-Technische Bundesanstalt, Bundesallee 100, 38116 Braunschweig (Germany)

    2014-06-21

    We investigate the application of nanoscale topgates on exfoliated bilayer graphene to define quantum dot devices. At temperatures below 500 mK, the conductance underneath the grounded gates is suppressed, which we attribute to nearest neighbour hopping and strain-induced piezoelectric fields. The gate-layout can thus be used to define resistive regions by tuning into the corresponding temperature range. We use this method to define a quantum dot structure in bilayer graphene showing Coulomb blockade oscillations consistent with the gate layout.

  6. 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.

  7. Spectroscopic characteristics of carbon dots (C-dots) derived from carbon fibers and conversion to sulfur-bridged C-dots nanosheets.

    Science.gov (United States)

    Vinci, John C; Ferrer, Ivonne M; Guterry, Nathan W; Colón, Verónica M; Destino, Joel F; Bright, Frank V; Colón, Luis A

    2015-09-01

    We synthesized sub-10 nm carbon nanoparticles (CNPs) consistent with photoluminescent carbon dots (C-dots) from carbon fiber starting material. The production of different C-dots fractions was monitored over seven days. During the course of the reaction, one fraction of C-dots species with relatively high photoluminescence was short-lived, emerging during the first hour of reaction but disappearing after one day of reaction. Isolation of this species during the first hour of the reaction was crucial to obtaining higher-luminescent C-dots species. When the reaction proceeded for one week, the appearance of larger nanostructures was observed over time, with lateral dimensions approaching 200 nm. The experimental evidence suggests that these larger species are formed from small C-dot nanoparticles bridged together by sulfur-based moieties between the C-dot edge groups, as if the C-dots polymerized by cross-linking the edge groups through sulfur bridges. Their size can be tailored by controlling the reaction time. Our results highlight the variety of CNP products, from sub-10 nm C-dots to ~200 nm sulfur-containing carbon nanostructures, that can be produced over time during the oxidation reaction of the graphenic starting material. Our work provides a clear understanding of when to stop the oxidation reaction during the top-down production of C-dots to obtain highly photoluminescent species or a target average particle size.

  8. 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...... to resolve luminescence lines from individual quantum dots, revealing an atomic-like spectrum of sharp transition lines. A parameter of fundamental importance is the intrinsic linewidth of these transitions. Using high-resolution spectroscopy we have determined the linewidth and investigated its dependence...... on temperature, which gives information about how the exciton confined to the quantum dot interacts with the surrounding lattice....

  9. 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

  10. Photoluminescent carbon dots from 1,4-addition polymers.

    Science.gov (United States)

    Jiang, Zhiqiang; Nolan, Andrew; Walton, Jeffrey G A; Lilienkampf, Annamaria; Zhang, Rong; Bradley, Mark

    2014-08-25

    Photoluminescent carbon dots were synthesised directly by thermopyrolysis of 1,4-addition polymers, allowing precise control of their properties. The effect of polymer composition on the properties of the carbon dots was investigated by TEM, IR, XPS, elemental analysis and fluorescence analysis, with carbon dots synthesised from nitrogen-containing polymers showing the highest fluorescence. The carbon dots with high nitrogen content were observed to have strong fluorescence in the visible region, and culture with cells showed that the carbon dots were non-cytotoxic and readily taken up by three different cell lines.

  11. 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.

  12. Sensitivity of quantum-dot semiconductor lasers to optical feedback.

    Science.gov (United States)

    O'Brien, D; Hegarty, S P; Huyet, G; Uskov, A V

    2004-05-15

    The sensitivity of quantum-dot semiconductor lasers to optical feedback is analyzed with a Lang-Kobayashi approach applied to a standard quantum-dot laser model. The carriers are injected into a quantum well and are captured by, or escape from, the quantum dots through either carrier-carrier or phonon-carrier interaction. Because of Pauli blocking, the capture rate into the dots depends on the carrier occupancy level in the dots. Here we show that different carrier capture dynamics lead to a strong modification of the damping of the relaxation oscillations. Regions of increased damping display reduced sensitivity to optical feedback even for a relatively large alpha factor.

  13. High-resolution photoluminescence studies of single semiconductor quantum dots

    DEFF Research Database (Denmark)

    Leosson, Kristjan; Østergaard, John Erland; Jensen, Jacob Riis;

    2000-01-01

    Semiconductor quantum dots, especially those formed by self-organized growth, are considered a promising material system for future optical devices [1] and the optical properties of quantum dot ensembles have been investigated in detail over the past years. Recently, considerable interest has...... developed in the study of single quantum dots, characterized by sharp atomic-like transition lines revealing their zero-dimensional density of states. Substantial information about the fundamental properties of individual quantum dots, as well as their interactions with other dots and the host lattice, can...

  14. 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.

  15. 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.

  16. 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

  17. 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).

  18. Learner-Centred Education in International Perspective

    Directory of Open Access Journals (Sweden)

    Michele Schweisfurth

    2013-04-01

    Full Text Available Abstract: This article provides an overview of Learner-Centred ducation (LCE as a travelling policy and outlines some of the arguments and pathways that have been used to fuel its travel. Despite the rich promises it offers and its proliferation as a global phenomenon and national policy, there is evidence that implementation and changes to classroom practice have proved to be problematic in many contexts. This seems particularly true in developing countries, and the article explores some of the reasons behind these perennial gaps. It concludes by arguing for the importance of both a birds-eye view and local understandings in researching and operationalising LCE, and suggests ways that the local and the global might be reconciled so that the promise of LCE is not lost in translation.

  19. 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.

  20. 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...

  1. 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.

  2. 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

  3. Communications Centre Model in Insurance Business

    Directory of Open Access Journals (Sweden)

    Danijel Bara

    2013-07-01

    Full Text Available The aim of this paper is to define a communications centre model in an insurance company that essentially has two objectives. The first objective is focused on providing quality support with the sales process thereby creating a strategic advantage over the competition while the second objective is focused on improving the link between internal organizational units whose behaviour can often render decision-making at all levels difficult. The function of sales is fundamental for an insurance company. Whether an insurance company will fulfil its basic function, which is transfer of risk from the insured party to the insurer who agrees tonreimburse incidental damages to the damaged party and distribute them among all members of the risk group on the principles of reciprocity and solidarity, depends on successful sales and billing (Andrijašević & Petranović, 1999. For an insurance company to operate successfully in a demanding market, it is necessary to meet the needs of potential clients who then must be at the centre of all the activities of the insurer. A satisfied policy holder, who is respected by the insurer as a partner, is a guarantee that the sales of insurance services will be successful and that the insured party will come back to the same insurance company. In the era of globalization and all-pervading new technologies and modes of communication, policy holders need to be able to communicate with insurance company employees. Quality communication is a good foundation for a sales conversation. A fast flow of all types of information within an organisation using a single communication module makes decision-making at all levels quicker and easier.

  4. Optical Properties of Quantum-Dot-Doped Liquid Scintillators

    CERN Document Server

    Aberle, C; Weiss, S; Winslow, L

    2013-01-01

    Semiconductor nanoparticles (quantum dots) were studied in the context of liquid scintillator development for upcoming neutrino experiments. The unique optical and chemical properties of quantum dots are particularly promising for the use in neutrinoless double beta decay experiments. Liquid scintillators for large scale neutrino detectors have to meet specific requirements which are reviewed, highlighting the peculiarities of quantum-dot-doping. In this paper, we report results on laboratory-scale measurements of the attenuation length and the fluorescence properties of three commercial quantum dot samples. The results include absorbance and emission stability measurements, improvement in transparency due to filtering of the quantum dot samples, precipitation tests to isolate the quantum dots from solution and energy transfer studies with quantum dots and the fluorophore PPO.

  5. 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.

  6. 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.

  7. 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.

  8. Electron Scattering in Intrananotube Quantum Dots

    NARCIS (Netherlands)

    Buchs, G.; Bercioux, D.; Ruffieux, P.; Gröning, P.; Grabert, H.; Gröning, O.

    2009-01-01

    Intratube quantum dots showing particle-in-a-box-like states with level spacings up to 200 meV are realized in metallic single-walled carbon nanotubes by means of low dose medium energy Ar+ irradiation. Fourier-transform scanning tunneling spectroscopy compared to results of a Fabry-Perot electron r

  9. 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...... (SOAs). Also the possibility of realizing an all-optical regenerator by incorporating a QD absorber section in an amplifier structure is discussed....

  10. 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.

  11. 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

  12. 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...

  13. 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.

  14. 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.

  15. 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:...

  16. Carbon dots (C-dots) from cow manure with impressive subcellular selectivity tuned by simple chemical modification.

    Science.gov (United States)

    D'Angelis do E S Barbosa, Cintya; Corrêa, José R; Medeiros, Gisele A; Barreto, Gabrielle; Magalhães, Kelly G; de Oliveira, Aline L; Spencer, John; Rodrigues, Marcelo O; Neto, Brenno A D

    2015-03-23

    Improved cellular selectivity for nucleoli staining was achieved by simple chemical modification of carbon dots (C-dots) synthesized from waste carbon sources such as cow manure (or from glucose). The C-dots were characterized and functionalized (amine-passivated) with ethylenediamine, affording amide bonds that resulted in bright green fluorescence. The new modified C-dots were successfully applied as selective live-cell fluorescence imaging probes with impressive subcellular selectivity and the ability to selectively stain nucleoli in breast cancer cell lineages (MCF-7). The C-dots were also tested in four other cellular models and showed the same cellular selection in live-cell imaging experiments.

  17. VIA Ageing and Dementia, Research Centre, VIA University College, Denmark

    DEFF Research Database (Denmark)

    Munk, Karen Pallesgaard; Maibom, Kirsten

    2016-01-01

    New research environments are evolving in Denmark. Following a legislative change in 2013, the conditions for research in University Colleges have been improved. University Colleges (professionshøjskoler) includes the undergraduate-level educations such as nursing, occupational therapy and physio...... and physiotherapy and related research centres. The article describes such a research centre, namely VIA Ageing and Dementia, Research Centre, VIA University College, Denmark....

  18. 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.

  19. Optical power limiting in ensembles of colloidal Ag{sub 2}S quantum dots

    Energy Technology Data Exchange (ETDEWEB)

    Ovchinnikov, O V; Smirnov, M S; Perepelitsa, A S; Shatskikh, T S [Voronezh State University, Voronezh (Russian Federation); Shapiro, B I [M.V. Lomonosov Moscow State Academy of Fine Chemical Technology, Moscow (Russian Federation)

    2015-12-31

    The effect of power limiting for optical radiation at a wavelength of 660 nm with a pulse duration of 10 ms and operation threshold of 2.2 – 3.1 mJ cm{sup -2} is observed in ensembles of colloidal Ag{sub 2}S quantum dots (QDs). Using the z-scanning method in an open-aperture scheme it is found that the power is limited mainly due to reverse saturable absorption caused by two-photon optical transitions that involve energy levels of Ag{sub 2}S photoluminescence centres, related to structural impurity defects in colloidal Ag{sub 2}S QDs. At the same time, the z-scanning in a closed-aperture scheme demonstrates the formation of a thermal dynamic lens. (nonlinear optical phenomena)

  20. Entrapment in phospholipid vesicles quenches photoactivity of quantum dots

    Directory of Open Access Journals (Sweden)

    Generalov R

    2011-09-01

    Full Text Available Roman Generalov1,2, Simona Kavaliauskiene1, Sara Westrøm1, Wei Chen3, Solveig Kristensen2, Petras Juzenas11Department of Radiation Biology, Institute for Cancer Research, Norwegian Radium Hospital, Oslo University Hospital, Oslo, Norway; 2School of Pharmacy, University of Oslo, Oslo, Norway; 3Department of Physics, The University of Texas at Arlington, Arlington, TX, USAAbstract: Quantum dots have emerged with great promise for biological applications as fluorescent markers for immunostaining, labels for intracellular trafficking, and photosensitizers for photodynamic therapy. However, upon entry into a cell, quantum dots are trapped and their fluorescence is quenched in endocytic vesicles such as endosomes and lysosomes. In this study, the photophysical properties of quantum dots were investigated in liposomes as an in vitro vesicle model. Entrapment of quantum dots in liposomes decreases their fluorescence lifetime and intensity. Generation of free radicals by liposomal quantum dots is inhibited compared to that of free quantum dots. Nevertheless, quantum dot fluorescence lifetime and intensity increases due to photolysis of liposomes during irradiation. In addition, protein adsorption on the quantum dot surface and the acidic environment of vesicles also lead to quenching of quantum dot fluorescence, which reappears during irradiation. In conclusion, the in vitro model of phospholipid vesicles has demonstrated that those quantum dots that are fated to be entrapped in endocytic vesicles lose their fluorescence and ability to act as photosensitizers.Keywords: fluorescence lifetime, free radicals, liposomes, lipodots, reactive oxygen species

  1. Entrapment in phospholipid vesicles quenches photoactivity of quantum dots.

    Science.gov (United States)

    Generalov, Roman; Kavaliauskiene, Simona; Westrøm, Sara; Chen, Wei; Kristensen, Solveig; Juzenas, Petras

    2011-01-01

    Quantum dots have emerged with great promise for biological applications as fluorescent markers for immunostaining, labels for intracellular trafficking, and photosensitizers for photodynamic therapy. However, upon entry into a cell, quantum dots are trapped and their fluorescence is quenched in endocytic vesicles such as endosomes and lysosomes. In this study, the photophysical properties of quantum dots were investigated in liposomes as an in vitro vesicle model. Entrapment of quantum dots in liposomes decreases their fluorescence lifetime and intensity. Generation of free radicals by liposomal quantum dots is inhibited compared to that of free quantum dots. Nevertheless, quantum dot fluorescence lifetime and intensity increases due to photolysis of liposomes during irradiation. In addition, protein adsorption on the quantum dot surface and the acidic environment of vesicles also lead to quenching of quantum dot fluorescence, which reappears during irradiation. In conclusion, the in vitro model of phospholipid vesicles has demonstrated that those quantum dots that are fated to be entrapped in endocytic vesicles lose their fluorescence and ability to act as photosensitizers.

  2. Studies of silicon quantum dots prepared at different substrate temperatures

    Science.gov (United States)

    Al-Agel, Faisal A.; Suleiman, Jamal; Khan, Shamshad A.

    2017-03-01

    In this research work, we have synthesized silicon quantum dots at different substrate temperatures 193, 153 and 123 K at a fixed working pressure 5 Torr. of Argon gas. The structural studies of these silicon quantum dots have been undertaken using X-ray diffraction, Field Emission Scanning Electron Microscopy (FESEM) and High Resolution Transmission Electron Microscopy (HRTEM). The optical and electrical properties have been studied using UV-visible spectroscopy, Fourier transform infrared (FTIR) spectroscopy, Fluorescence spectroscopy and I-V measurement system. X-ray diffraction pattern of Si quantum dots prepared at different temperatures show the amorphous nature except for the quantum dots synthesized at 193 K which shows polycrystalline nature. FESEM images of samples suggest that the size of quantum dots varies from 2 to 8 nm. On the basis of UV-visible spectroscopy measurements, a direct band gap has been observed for Si quantum dots. FTIR spectra suggest that as-grown Si quantum dots are partially oxidized which is due exposure of as-prepared samples to air after taking out from the chamber. PL spectra of the synthesized silicon quantum dots show an intense peak at 444 nm, which may be attributed to the formation of Si quantum dots. Temperature dependence of dc conductivity suggests that the dc conductivity enhances exponentially by raising the temperature. On the basis above properties i.e. direct band gap, high absorption coefficient and high conductivity, these silicon quantum dots will be useful for the fabrication of solar cells.

  3. 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

  4. Mass Segregation in the Galactic Centre

    CERN Document Server

    Hopman, Clovis

    2010-01-01

    Two-body energy exchange between stars orbiting massive black holes (MBHs) leads to the formation of a power-law density distribution n(r)~r^(-a) that diverges towards the MBH. For a single mass population, a=7/4 and the flow of stars is much less than N(centre (GC) is t_r ~2-3 * 10^(10) yr, a cusp should form in less than a Hubble time. The absence of a visible cusp of old stars in the GC poses a challenge to these models, ...

  5. Detecting pulsars in the Galactic centre

    CERN Document Server

    Rajwade, Kaustubh; Anderson, Loren

    2016-01-01

    Although high-sensitivity surveys have revealed a number of highly dispersed pulsars in the inner Galaxy, none have so far been found in the Galactic centre (GC) region, which we define to be within a projected distance of 1~pc from Sgr~A*. This null result is surprising given that several independent lines of evidence predict a sizeable population of neutron stars in the region. Here, we present a detailed analysis of both the canonical and millisecond pulsar populations in the GC and consider free-free absorption and multi-path scattering to be the two main sources of flux mitigation. We demonstrate the sensitivity limits of previous surveys are not sufficient to detect GC pulsar population, and investigate the optimum observing frequency for future surveys. Depending on the degree of scattering and free-free absorption in the GC, current surveys constrain the size of the potentially observable population (i.e. those beaming towards us) to be up to 50 canonical pulsars and 1430 millisecond pulsars. We find ...

  6. The Galactic Centre in the Far Infrared

    CERN Document Server

    Etxaluze, M; Tolls, V; Stark, A A; Gonzalez-Alfonso, E

    2011-01-01

    We analyse the far infrared dust emission from the Galactic Centre region, including the Circumnuclear Disk (CND) and other structures, using Herschel PACS and SPIRE photometric observations. These Herschel data are complemented by unpublished observations by the Infrared Space Observatory Long Wavelength Spectrometer (ISO LWS), which used parallel mode scans to obtain photometric images of the region with a larger beam than Herschel but with a complementary wavelength coverage and more frequent sampling with ten detectors observing at ten different wavelengths in the range from 46 to 180 \\mum, where the emission peaks. We also include data from the MSX at 21.3 \\mum for completeness. We model the combined ISO LWS continuum plus Herschel PACS and SPIRE photometric data toward the central 2 pc in Sgr A*, a region that includes the CND. We find that the FIR spectral energy distribution is best represented by a continuum that is the sum of three greybody curves from dust at temperatures of 90, 44.5, and 23 K. We ...

  7. 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.

  8. 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 ...

  9. 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...

  10. The Charles Perkins Centre's Twins Research Node.

    Science.gov (United States)

    Ferreira, Lucas C; Craig, Jeffrey M; Hopper, John L; Carrick, Susan E

    2016-08-01

    Twins can help researchers disentangle the roles of genes from those of the environment on human traits, health, and diseases. To realize this potential, the Australian Twin Registry (ATR), University of Melbourne, and the Charles Perkins Centre (CPC), University of Sydney, established a collaboration to form the Twins Research Node, a highly interconnected research facility dedicated specifically to research involving twins. This collaboration aims to foster the adoption of twin designs as important tools for research in a range of health-related domains. The CPC hosted their Twins Research Node's launch seminar entitled 'Double the power of your research with twin studies', in which experienced twin researchers described how twin studies are supporting scientific discoveries and careers. The launch also featured twin pairs who have actively participated in research through the ATR. Researchers at the CPC were surveyed before the event to gauge their level of understanding and interest in utilizing twin research. This article describes the new Twins Research Node, discusses the survey's main results and reports on the launch seminar.

  11. 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...

  12. 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...

  13. 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

  14. 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…

  15. Low-Income Parents' Adult Interactions at Childcare Centres

    Science.gov (United States)

    Reid, Jeanne L.; Martin, Anne; Brooks-Gunn, Jeanne

    2017-01-01

    Little is known about the extent and nature of low-income parents' interactions with other parents and staff at childcare centres, despite the potential for these interactions to provide emotional, informational, and instrumental support. This study interviewed 51 parents at three childcare centres in low-income neighbourhoods in New York City.…

  16. Science Centres: A Resource for School and Community

    Science.gov (United States)

    Pilo, Miranda; Mantero, Alfonso; Marasco, Antonella

    2011-01-01

    We present a science centre established in Genoa on an agreement between Municipality of Genoa and Department of Physics of University of Genoa. The aim is to offer children, young people and community an opportunity to approach science in a playful way. The centre staffs guide the visitors through the exhibits, attracting their interests towards…

  17. 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.

  18. The Hierarchy Model of the Size Distribution of Centres

    NARCIS (Netherlands)

    J. Tinbergen (Jan)

    1968-01-01

    textabstractWe know that human beings live in centres, that is, cities, towns and villages of different size. Both large and small centres have a number of advantages and disadvantages, different for different people and this is why we have a whole range of sizes. Statistically, we even find that th

  19. 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.

  20. Stromal networking: cellular connections in the germinal centre.

    Science.gov (United States)

    Denton, Alice E; Linterman, Michelle A

    2017-03-17

    Secondary lymphoid organs are organized into distinct zones, governed by different types of mesenchymal stromal cells. These stromal cell subsets are critical for the generation of protective humoral immunity because they direct the migration of, and interaction between, multiple immune cell types to form the germinal centre. The germinal centre response generates long-lived antibody-secreting plasma cells and memory B cells which can provide long-term protection against re-infection. Stromal cell subsets mediate this response through control of immune cell trafficking, activation, localization and antigen access within the secondary lymphoid organ. Further, distinct populations of stromal cells underpin the delicate spatial organization of immune cells within the germinal centre. Because of this, the interactions between immune cells and stromal cells in secondary lymphoid organs are fundamental to the germinal centre response. Herein we review how this unique relationship leads to effective germinal centre responses.

  1. Nanobeam photonic crystal cavity quantum dot laser

    CERN Document Server

    Gong, Yiyang; Shambat, Gary; Sarmiento, Tomas; Harris, James S; Vuckovic, Jelena

    2010-01-01

    The lasing behavior of one dimensional GaAs nanobeam cavities with embedded InAs quantum dots is studied at room temperature. Lasing is observed throughout the quantum dot PL spectrum, and the wavelength dependence of the threshold is calculated. We study the cavity lasers under both 780 nm and 980 nm pump, finding thresholds as low as 0.3 uW and 19 uW for the two pump wavelengths, respectively. Finally, the nanobeam cavity laser wavelengths are tuned by up to 7 nm by employing a fiber taper in near proximity to the cavities. The fiber taper is used both to efficiently pump the cavity and collect the cavity emission.

  2. 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.

  3. 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.

  4. Energy level statistics of quantum dots.

    Science.gov (United States)

    Tsau, Chien-Yu; Nghiem, Diu; Joynt, Robert; Woods Halley, J

    2007-05-08

    We investigate the charging energy level statistics of disordered interacting electrons in quantum dots by numerical calculations using the Hartree approximation. The aim is to obtain a global picture of the statistics as a function of disorder and interaction strengths. We find Poisson statistics at very strong disorder, Wigner-Dyson statistics for weak disorder and interactions, and a Gaussian intermediate regime. These regimes are as expected from previous studies and fundamental considerations, but we also find interesting and rather broad crossover regimes. In particular, intermediate between the Gaussian and Poisson regimes we find a two-sided exponential distribution for the energy level spacings. In comparing with experiment, we find that this distribution may be realized in some quantum dots.

  5. Design of tunneling injection quantum dot lasers

    Institute of Scientific and Technical Information of China (English)

    JIA Guo-zhi; YAO Jiang-hong; SHU Yong-chun; WANG Zhan-guo

    2007-01-01

    To implement high quality tunneling injection quantum dot lasers,effects of primary factors on performance of the tunneling injection quantum dot lasers were investigated. The considered factors were tunneling probability,tunneling time and carriers thermal escape time from the quantum well. The calculation results show that with increasing of the ground-state energy level in quantum well,the tunneling probability increases and the tunneling time decreases,while the thermal escape time decreases because the ground-state energy levelis shallower. Longitudinal optical phonon-assisted tunneling can be an effective method to solve the problem that both the tunneling time and the thermal escape time decrease simultaneously with the ground-state energy level increasing in quantum well.

  6. 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.

  7. Energy level statistics of quantum dots

    Energy Technology Data Exchange (ETDEWEB)

    Tsau, C-Y [University of Wisconsin-Madison, Madison, WI 53706 (United States); Nghiem, Diu [University of Wisconsin-Madison, Madison, WI 53706 (United States); Joynt, Robert [University of Wisconsin-Madison, Madison, WI 53706 (United States); Halley, J Woods [School of Physics and Astronomy, University of Minnesota, Minneapolis, MN 55455 (United States)

    2007-05-08

    We investigate the charging energy level statistics of disordered interacting electrons in quantum dots by numerical calculations using the Hartree approximation. The aim is to obtain a global picture of the statistics as a function of disorder and interaction strengths. We find Poisson statistics at very strong disorder, Wigner-Dyson statistics for weak disorder and interactions, and a Gaussian intermediate regime. These regimes are as expected from previous studies and fundamental considerations, but we also find interesting and rather broad crossover regimes. In particular, intermediate between the Gaussian and Poisson regimes we find a two-sided exponential distribution for the energy level spacings. In comparing with experiment, we find that this distribution may be realized in some quantum dots.

  8. Energy level statistics of quantum dots

    Science.gov (United States)

    Tsau, Chien-Yu; Nghiem, Diu; Joynt, Robert; Halley, J. Woods

    2007-05-01

    We investigate the charging energy level statistics of disordered interacting electrons in quantum dots by numerical calculations using the Hartree approximation. The aim is to obtain a global picture of the statistics as a function of disorder and interaction strengths. We find Poisson statistics at very strong disorder, Wigner-Dyson statistics for weak disorder and interactions, and a Gaussian intermediate regime. These regimes are as expected from previous studies and fundamental considerations, but we also find interesting and rather broad crossover regimes. In particular, intermediate between the Gaussian and Poisson regimes we find a two-sided exponential distribution for the energy level spacings. In comparing with experiment, we find that this distribution may be realized in some quantum dots.

  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. Peptide-Decorated Tunable-Fluorescence Graphene Quantum Dots.

    Science.gov (United States)

    Sapkota, Bedanga; Benabbas, Abdelkrim; Lin, Hao-Yu Greg; Liang, Wentao; Champion, Paul; Wanunu, Meni

    2017-03-22

    We report here the synthesis of graphene quantum dots with tunable size, surface chemistry, and fluorescence properties. In the size regime 15-35 nm, these quantum dots maintain strong visible light fluorescence (mean quantum yield of 0.64) and a high two-photon absorption (TPA) cross section (6500 Göppert-Mayer units). Furthermore, through noncovalent tailoring of the chemistry of these quantum dots, we obtain water-stable quantum dots. For example, quantum dots with lysine groups bind strongly to DNA in solution and inhibit polymerase-based DNA strand synthesis. Finally, by virtue of their mesoscopic size, the quantum dots exhibit good cell permeability into living epithelial cells, but they do not enter the cell nucleus.

  11. 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.

  12. Principles of conjugating quantum dots to proteins via carbodiimide chemistry.

    Science.gov (United States)

    Song, Fayi; Chan, Warren C W

    2011-12-09

    The covalent coupling of nanomaterials to bio-recognition molecules is a critical intermediate step in using nanomaterials for biology and medicine. Here we investigate the carbodiimide-mediated conjugation of fluorescent quantum dots to different proteins (e.g., immunoglobulin G, bovine serum albumin, and horseradish peroxidase). To enable these studies, we developed a simple method to isolate quantum dot bioconjugates from unconjugated quantum dots. The results show that the reactant concentrations and protein type will impact the overall number of proteins conjugated onto the surfaces of the quantum dots, homogeneity of the protein-quantum dot conjugate population, quantum efficiency, binding avidity, and enzymatic kinetics. We propose general principles that should be followed for the successful coupling of proteins to quantum dots.

  13. 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.

  14. 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.

  15. 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

  16. 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.

  17. 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......The present thesis reports research on the optical properties of quantum dots by developing new theories and conducting optical measurements. We demonstrate experimentally singlephoton superradiance in interface-uctuation quantum dots by recording the temporal decay dynamics in conjunction...

  18. DLTS measurements on GaSb/GaAs quantum dots

    Energy Technology Data Exchange (ETDEWEB)

    Hoegner, Annika; Nowozin, Tobias; Marent, Andreas; Bimberg, Dieter [Institut fuer Festkoerperphysik, TU Berlin (Germany); Tseng, Chi-Che [Institute of Photonics Technologies, NTHU (China); Lin, Shih-Yen [Institute of Optoelectronic Sciences, NTOU (China)

    2010-07-01

    Memory devices based on hole storage in self-organized quantum dots offer significant advantages with respect to storage time and scalability. Recently, we demonstrated a first prototype based on InAs/GaAs quantum dots at low temperatures. To enable feasible storage times at room temperature the localisation energy of the quantum dots has to be increased by using other material systems. A first step in this direction is the use of GaSb quantum dots within a GaAs matrix. We have characterized self-organized GaSb/GaAs quantum dots embedded into a n{sup +}p-diode structure. DLTS measurements on hole emission were conducted and yield a strong peak from which a mean emission energy of about 400 meV can be extracted. The reference sample without the quantum dots (containing only the wetting layer) shows no such peak.

  19. 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.

  20. 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.

  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. Pharmaceutical and biomedical applications of quantum dots.

    Science.gov (United States)

    Bajwa, Neha; Mehra, Neelesh K; Jain, Keerti; Jain, Narendra K

    2016-05-01

    Quantum dots (QDs) have captured the fascination and attention of scientists due to their simultaneous targeting and imaging potential in drug delivery, in pharmaceutical and biomedical applications. In the present study, we have exhaustively reviewed various aspects of QDs, highlighting their pharmaceutical and biomedical applications, pharmacology, interactions, and toxicological manifestations. The eventual use of QDs is to dramatically improve clinical diagnostic tests for early detection of cancer. In recent years, QDs were introduced to cell biology as an alternative fluorescent probe.

  3. Depleted bulk heterojunction colloidal quantum dot photovoltaics

    Energy Technology Data Exchange (ETDEWEB)

    Barkhouse, D.A.R. [Department of Electrical and Computer Engineering, University of Toronto, 10 King' s College Road, Toronto, Ontario M5S 3G4 (Canada); IBM Thomas J. Watson Research Center, Kitchawan Road, Yorktown Heights, NY, 10598 (United States); Debnath, Ratan; Kramer, Illan J.; Zhitomirsky, David; Levina, Larissa; Sargent, Edward H. [Department of Electrical and Computer Engineering, University of Toronto, 10 King' s College Road, Toronto, Ontario M5S 3G4 (Canada); Pattantyus-Abraham, Andras G. [Department of Electrical and Computer Engineering, University of Toronto, 10 King' s College Road, Toronto, Ontario M5S 3G4 (Canada); Quantum Solar Power Corporation, 1055 W. Hastings, Ste. 300, Vancouver, BC, V6E 2E9 (Canada); Etgar, Lioz; Graetzel, Michael [Laboratory for Photonics and Interfaces, Institute of Chemical Sciences and Engineering, School of Basic Sciences, Swiss Federal Institute of Technology, CH-1015 Lausanne (Switzerland)

    2011-07-26

    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 copyright 2011 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  4. Barrier Engineered Quantum Dot Infrared Photodetectors

    Science.gov (United States)

    2015-06-01

    Advisor, Space Based Advanced Sensing and Protection //SIGNED// JOHN BEAUCHEMIN Chief Engineer, Spacecraft Technology Division Space Vehicles...QD based device can be further improved by planting the dots into a CE DWELL structure to reduce the operating bias while maintaining good...noteworthy low operating bias voltage indicates its feasibility for fabrication of FPA using commercially available silicon read-out circuits. Figure 3. (a

  5. Quantum-dot excitons in nanostructured environments

    DEFF Research Database (Denmark)

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

    2011-01-01

    The interaction between light and quantum-dot (QD) excitons is strongly influenced by the environment in which the QD is placed. We have investigated the interaction by measuring the time-resolved spontaneous-emission rate of QD excitons in different nanostructured environments. Thereby, we have...... is demonstrated and the influence of disorder is discussed. The findings have a strong bearing on future nanophotonic devices....

  6. Quantum-dot excitons in nanostructured environments

    DEFF Research Database (Denmark)

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

    2010-01-01

    The interaction between light and quantum-dot (QD) excitons is strongly influenced by the environment in which the QD is placed. We have investigated the interaction by measuring the time-resolved spontaneous-emission rate of QD excitons in different nanostructured environments. Thereby, we have...... is demonstrated and the influence of disorder is discussed. The findings have a strong bearing on future nanophotonic devices....

  7. 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.

  8. 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

    2014-12-01

    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 these questions. This paper examines the phenomenon of tutorial centres in Hong Kong and seeks to understand what draws students to these centres. Combining theories of marketing semiotics and emotion studies, the author investigates the pivotal role of media marketing in generating the "magic" of tutorial centres, whose advertising strategy includes, for example, a display of billboard posters featuring stylishly-dressed "celebrity teachers". The author reviews some of the literature available on the subject of tutorial centres. In a case study approach, he then maps out the pedagogy he observed in an English tutorial class, seeking heuristic insights into the kind of teaching students in the study were looking for. He argues that part of the "magical" attraction of what are essentially "cram schools" is their formulaic pedagogy of teaching and reinforcing exam skills. Finally, the paper considers the social implications of the tutorial centre industry in terms of media marketing of education and unequal access to tutorial services.

  9. Student-Centred and Teacher-Centred Learning Environment in Pre-Vocational Secondary Education: Psychological Needs, and Motivation

    Science.gov (United States)

    Smit, Karin; de Brabander, Cornelis J.; Martens, Rob L.

    2014-01-01

    In this study the perception of psychological needs and motivation in a student-centred and a teacher-centred learning environment are compared, using Self Determination Theory as a framework. The self-report Intrinsic Motivation Inventory was completed by 230 students (mean age 16.1 years) in pre-vocational secondary education. School records on…

  10. Local Gate Control of a Carbon Nanotube Double Quantum Dot

    Science.gov (United States)

    2016-04-04

    Nanotube Double Quantum Dot N. Mason,*† M. J. Biercuk,* C. M. Marcus† We have measured carbon nanotube quantum dots with multiple electro- static gates and...used the resulting enhanced control to investigate a nano- tube double quantum dot. Transport measurements reveal honeycomb charge stability diagrams...This ability to control electron interactions in the quantum regime in a molecular conductor is important for applications such as quantum

  11. Gates controlled parallel-coupled bilayer graphene double quantum dot

    CERN Document Server

    Wang, Lin-Jun; Wei, Da; Cao, Gang; Tu, Tao; Xiao, Ming; Guo, Guang-Can; Chang, A M

    2011-01-01

    Here we report the fabrication and quantum transport measurements of gates controlled parallel-coupled bilayer graphene double quantum dot. It is shown that the interdot coupling strength of the parallel double dots can be effectively tuned from weak to strong regime by both the in-plane plunger gates and back gate. All the relevant energy scales and parameters of the bilayer graphene parallel-coupled double dot can be extracted from the honeycomb charge stability diagrams revealed through the transport measurements.

  12. 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.

  13. Aerial measurement error with a dot planimeter: Some experimental estimates

    Science.gov (United States)

    Yuill, R. S.

    1971-01-01

    A shape analysis is presented which utilizes a computer to simulate a multiplicity of dot grids mathematically. Results indicate that the number of dots placed over an area to be measured provides the entire correlation with accuracy of measurement, the indices of shape being of little significance. Equations and graphs are provided from which the average expected error, and the maximum range of error, for various numbers of dot points can be read.

  14. Local Quantum Dot Tuning on Photonic Crystal Chips

    CERN Document Server

    Faraon, Andrei; Fushman, Ilya; Stoltz, Nick; Petroff, Pierre; Vuckovic, Jelena

    2007-01-01

    Quantum networks based on InGaAs quantum dots embedded in photonic crystal devices rely on QDs being in resonance with each other and with the cavities they are embedded in. We developed a new technique based on temperature tuning to spectrally align different quantum dots located on the same chip. The technique allows for up to 1.8nm reversible on-chip quantum dot tuning.

  15. 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.

  16. 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.

  17. Production and targeting of monovalent quantum dots.

    Science.gov (United States)

    Seo, Daeha; Farlow, Justin; Southard, Kade; Jun, Young-Wook; Gartner, Zev J

    2014-10-23

    The multivalent nature of commercial quantum dots (QDs) and the difficulties associated with producing monovalent dots have limited their applications in biology, where clustering and the spatial organization of biomolecules is often the object of study. We describe here a protocol to produce monovalent quantum dots (mQDs) that can be accomplished in most biological research laboratories via a simple mixing of CdSe/ZnS core/shell QDs with phosphorothioate DNA (ptDNA) of defined length. After a single ptDNA strand has wrapped the QD, additional strands are excluded from the surface. Production of mQDs in this manner can be accomplished at small and large scale, with commercial reagents, and in minimal steps. These mQDs can be specifically directed to biological targets by hybridization to a complementary single stranded targeting DNA. We demonstrate the use of these mQDs as imaging probes by labeling SNAP-tagged Notch receptors on live mammalian cells, targeted by mQDs bearing a benzylguanine moiety.

  18. Interference and interactions in open quantum dots

    CERN Document Server

    Bird, J P; Ferry, D K; Moura, A P S; Lai, Y C; Indlekofer, K M

    2003-01-01

    In this report, we review the results of our joint experimental and theoretical studies of electron-interference, and interaction, phenomena in open electron cavities known as quantum dots. The transport through these structures is shown to be heavily influenced by the remnants of their discrete density of states, elements of which remain resolved in spite of the strong coupling that exists between the cavity and its reservoirs. The experimental signatures of this density of states are discussed at length in this report, and are shown to be related to characteristic wavefunction scarring, involving a small number of classical orbits. A semiclassical analysis of this behaviour shows it to be related to the effect of dynamical tunnelling, in which electrons are injected into the dot tunnel through classically forbidden regions of phase space, to access isolated regular orbits. The dynamical tunnelling gives rise to the formation of long-lived quasi-bound states in the open dots, and the many-body implications a...

  19. Probing relaxation times in graphene quantum dots

    Science.gov (United States)

    Volk, Christian; Neumann, Christoph; Kazarski, Sebastian; Fringes, Stefan; Engels, Stephan; Haupt, Federica; Müller, André; Stampfer, Christoph

    2013-01-01

    Graphene quantum dots are attractive candidates for solid-state quantum bits. In fact, the predicted weak spin-orbit and hyperfine interaction promise spin qubits with long coherence times. Graphene quantum dots have been extensively investigated with respect to their excitation spectrum, spin-filling sequence and electron-hole crossover. However, their relaxation dynamics remain largely unexplored. This is mainly due to challenges in device fabrication, in particular concerning the control of carrier confinement and the tunability of the tunnelling barriers, both crucial to experimentally investigate decoherence times. Here we report pulsed-gate transient current spectroscopy and relaxation time measurements of excited states in graphene quantum dots. This is achieved by an advanced device design that allows to individually tune the tunnelling barriers down to the low megahertz regime, while monitoring their asymmetry. Measuring transient currents through electronic excited states, we estimate a lower bound for charge relaxation times on the order of 60–100 ns. PMID:23612294

  20. Nonrenewal statistics in transport through quantum dots

    Science.gov (United States)

    Ptaszyński, Krzysztof

    2017-01-01

    The distribution of waiting times between successive tunneling events is an already established method to characterize current fluctuations in mesoscopic systems. Here, I investigate mechanisms generating correlations between subsequent waiting times in two model systems, a pair of capacitively coupled quantum dots and a single-level dot attached to spin-polarized leads. Waiting time correlations are shown to give insight into the internal dynamics of the system; for example they allow distinction between different mechanisms of the noise enhancement. Moreover, the presence of correlations breaks the validity of the renewal theory. This increases the number of independent cumulants of current fluctuation statistics, thus providing additional sources of information about the transport mechanism. I also propose a method for inferring the presence of waiting time correlations based on low-order current correlation functions. This method gives a way to extend the analysis of nonrenewal current fluctuations to the systems for which single-electron counting is not experimentally feasible. The experimental relevance of the findings is also discussed; for example reanalysis of previous results concerning transport in quantum dots is suggested.

  1. Hillary Clinton impressed by the Centre's work.

    Science.gov (United States)

    1995-01-01

    In April 1994, US First Lady Hillary Rodham Clinton, her daughter Chelsea, the Bangladesh Minister for Women and Children's Affairs, and the US Ambassador to Bangladesh visited the International Centre for Diarrhoeal Disease Research, Bangladesh (ICDDR,B). The First Lady remarked that ICDDR,B's research programs on health and family planning have many important lessons for the developing and developed regions alike. She noted the development successes in Bangladesh that can be applied in the US and other countries: the Grameen Bank, oral rehydration solution (ORS), and the community outreach programs for health and family planning services. The First Lady was especially interested in ORS and its cost-effectiveness. Most of the 220,000 children hospitalized each year in the US for severe gastrointestinal illness are treated with expensive intravenous (IV) drips (average cost = $2300), while a few ORS packets would be a small fraction of the cost. The average cost of treatment per patient at ICDDR,B was only $12. Patients receive care free of charge. Less than 0.6% of the patients die. The previous year, a USAID administrator asked ICDDR,B for its expertise in fighting cholera at the Rwandan refugee camps in Goma, Zaire. ICDDR,B staff developed diagnostic antisera for the new cholera strain responsible for the epidemic in the Americas, described its pathophysiology, and established its mode of transmission in surface waters. ICDDR,B also provides technical support to the national family planning and maternal and child health programs. In the Matlab, ICDDR,B's work has contributed to a high contraceptive prevalence rate of more than 64% among poor and largely illiterate persons.

  2. Thermoelectric study of dissipative quantum-dot heat engines

    Science.gov (United States)

    De, Bitan; Muralidharan, Bhaskaran

    2016-10-01

    This paper examines the thermoelectric response of a dissipative quantum-dot heat engine based on the Anderson-Holstein model in two relevant operating limits, (i) when the dot phonon modes are out of equilibrium, and (ii) when the dot phonon modes are strongly coupled to a heat bath. In the first case, a detailed analysis of the physics related to the interplay between the quantum-dot level quantization, the on-site Coulomb interaction, and the electron-phonon coupling on the thermoelectric performance reveals that an n -type heat engine performs better than a p -type heat engine. In the second case, with the aid of the dot temperature estimated by incorporating a thermometer bath, it is shown that the dot temperature deviates from the bath temperature as electron-phonon interaction in the dot becomes stronger. Consequently, it is demonstrated that the dot temperature controls the direction of phonon heat currents, thereby influencing the thermoelectric performance. Finally, the conditions on the maximum efficiency with varying phonon couplings between the dot and all the other macroscopic bodies are analyzed in order to reveal the nature of the optimum junction.

  3. 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.

  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. Multicolor Nitrogen-Doped Carbon Dots for Live Cell Imaging.

    Science.gov (United States)

    Du, Fengyi; Li, Jianan; Hua, Ye; Zhang, Miaomiao; Zhou, Zhou; Yuan, Jing; Wang, Jun; Peng, Wanxin; Zhang, Li; Xia, Sheng; Wang, Dongqing; Yang, Shiming; Xu, Wenrong; Gong, Aihua; Shao, Qixiang

    2015-05-01

    Doping carbon dots with nitrogen atoms considerably enhances their fluorescence properties. However, the mechanism by which the carbon dots are doped is not fully understood. We developed a facile bottom-up hydrothermal carbonization (HTC) process that uses glucose and glycine as precursors for the synthesis of photoluminescent nitrogen-doped carbon dots. The as-prepared nitrogen-doped carbon dots were mono-dispersed spherical particles with a diameter of -2.8 nm. The doped nitrogen atoms assumed pyridinic type and pyrrolic type configurations to participate in the nanocrystal structure of the carbon dots. It appeared that the nitrogen doping introduces a new internal structure. The aqueous solution of nitrogen-doped carbon dots showed excitation wavelength-dependent multicolor photoluminescence. Further, these nitrogen-doped carbon dots readily entered the cytoplasm of A549 cancer cells and showed no significant cytotoxicity. The internalized nitrogen-doped carbon dots were localized to the cell membrane and cytoplasm, particularly around the nucleus. Further, the as-prepared, biocompatible, nitrogen-doped carbon dots demonstrated the potential to be used as fluorescent probes for multicolor live cell labeling, tracking, and imaging.

  6. 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.

  7. 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.

  8. Synthesis of CdSe Quantum Dots Using Fusarium oxysporum

    OpenAIRE

    Takaaki Yamaguchi; Yoshijiro Tsuruda; Tomohiro Furukawa; Lumi Negishi; Yuki Imura; Shohei Sakuda; Etsuro Yoshimura; Michio Suzuki

    2016-01-01

    CdSe quantum dots are often used in industry as fluorescent materials. In this study, CdSe quantum dots were synthesized using Fusarium oxysporum. The cadmium and selenium concentration, pH, and temperature for the culture of F. oxysporum (Fusarium oxysporum) were optimized for the synthesis, and the CdSe quantum dots obtained from the mycelial cells of F. oxysporum were observed by transmission electron microscopy. Ultra-thin sections of F. oxysporum showed that the CdSe quantum dots were pr...

  9. Advanced Architecture for Colloidal PbS Quantum Dot Solar Cells Exploiting a CdSe Quantum Dot Buffer Layer.

    Science.gov (United States)

    Zhao, Tianshuo; Goodwin, Earl D; Guo, Jiacen; Wang, Han; Diroll, Benjamin T; Murray, Christopher B; Kagan, Cherie R

    2016-09-22

    Advanced architectures are required to further improve the performance of colloidal PbS heterojunction quantum dot solar cells. Here, we introduce a CdI2-treated CdSe quantum dot buffer layer at the junction between ZnO nanoparticles and PbS quantum dots in the solar cells. We exploit the surface- and size-tunable electronic properties of the CdSe quantum dots to optimize its carrier concentration and energy band alignment in the heterojunction. We combine optical, electrical, and analytical measurements to show that the CdSe quantum dot buffer layer suppresses interface recombination and contributes additional photogenerated carriers, increasing the open-circuit voltage and short-circuit current of PbS quantum dot solar cells, leading to a 25% increase in solar power conversion efficiency.

  10. 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.

  11. Synthesis, Structure and Magnetic Properties of the Sandwich-type Tungstoarsenates Containing Tetrametallic Cluster[M4(H2O)2(AsW9O34)2]10-(M=CuⅡ, CoⅡ, MnⅡ, NiⅡ, ZnⅡ)%四金属簇钨砷夹心型化合物[M4(H2O)2·(AsW9O34)2]10-(M=CuⅡ, CoⅡ, MnⅡ, NiⅡ, ZnⅡ)的合成、结构和磁特性研究

    Institute of Scientific and Technical Information of China (English)

    毕立华; 黄如丹; 彭军; 王恩波

    2002-01-01

    @@ 取代型杂多化合物可改变多酸化合物的酸碱性、氧化还原性和热稳定性,因而受到关注[1]. 夹心型化合物是一类新型化合物,具有大的摩尔质量,高的负电荷,且含有多个磁性中心,近年来已引起国内外的兴趣[2].

  12. A designated centre for people with disabilities operated by St Aidan's Day Care Centre Ltd., Wexford

    LENUS (Irish Health Repository)

    Gibbons, C

    2015-02-01

    Ireland has seen a steady increase in paediatric sickle cell disease (SCD). In 2005, only 25% of children with SCD were referred to the haemoglobinopathy service in their first year. A non-funded screening programme was implemented. This review aimed to assess the impact screening has had. All children referred to the haemoglobinopathy service born in Ireland after 2005 were identified. Data was collected from the medical chart and laboratory system. Information was analysed using Microsoft Excel. 77 children with SCD were identified. The median age at antibiotic commencement in the screened group was 56 days compared with 447 days in the unscreened group, p = < 0.0003. 22 (28%) of infants were born in centre\\'s that do not screen and 17 (81%) were over 6 months old at referral, compared with 14 (21%) in the screened group. 6 (27%) of those in the unscreened group presented in acute crisis compared with 2 (3%) in the screened population. The point prevalence of SCD in Ireland is 0.2% in children under 15 yr of African and Asian descent. We identified delays in referral and treatment, which reflect the lack of government funded support and policy. We suggest all maternity units commence screening for newborns at risk of SCD. It is a cost effective intervention with a number needed to screen of just 4 to prevent a potentially fatal crisis.

  13. 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.

  14. 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.

  15. The Effectiveness of Family-Based DOTS versus Professional-Family Mix DOTS in Treating Smears Positive Tuberculosis

    Directory of Open Access Journals (Sweden)

    Hassan Yekrang Sis

    2014-07-01

    Full Text Available Background: The present study compared the effectiveness of Family-Based DOTS (FB-DOTS versus Professional-Family Mix DOTS (PFM-DOTS in smear positive tuberculosis (TB patients. Methods: This semi-experimental study was performed in Tuberculosis and Lung Diseases Research Center of Tabriz in 2011-2012, among 57 TB patients recruited into either FB-DOTS or PFM-DOTS groups. At the baseline of the study, knowledge of both patients and their supervisors were assessed while at the end point, smear and culture of sputum, quality of life, knowledge and satisfaction of the patients along with the knowledge and satisfaction of their super-visors were assessed. Results: The difference for sputum smear negative (culture was 16.2 (4.8% and 7.7(6.9% for the PFM-DOTS in comparison with FB DOTS by the end of the second and forth months of treatment, respectively. A significant difference was observed between the two groups in relation to knowledge, satisfaction (patients and supervisors and all four domains of quality of life: physical health (P=0.036, psychological health (P<0.001, social relations (P=0.026 and environmental health (P<0.001. Conclusion: The PFM-DOTS treatment strategy in which health experts follow the patients in their homes seems to be among most appropriate strategies in treating TB.

  16. Role of logistics centres in national logistics system

    Directory of Open Access Journals (Sweden)

    2010-06-01

    Full Text Available This article presents a division of logistics centres according to various criteria and specifies their role in a national logistics system. It provides a classification of the main logistics network nodes. It also describes those features of logistics centres that have an impact on zoning development of towns and regions. The current situation in the national logistics system has been presented here against theoretical analyses and also a concept for the development of a logistics centre network in Poland has been formulated.

  17. Negotiating active ageing at a Danish activity centre

    DEFF Research Database (Denmark)

    Lassen, Aske Juul

    and practices active ageing. The paper uses an activity centre in Copenhagen as its site of negotiation. Methods: These questions have been explored with the use of ethnographic fieldwork and through a documentary study. The ethnographic fieldwork has been conducted at an activity centre with 4 months...... of participatory observation in 2011 and 2012, as well as 11 semi-structured, in-depth interviews with users of the centre. 4 of these users have been followed around during everyday activities such as doing groceries, picking up grandchildren, etc. The documentary study consists of documents and statements...

  18. The experience of work in a call centre environment

    Directory of Open Access Journals (Sweden)

    Sanet Hauptfleisch

    2006-02-01

    Full Text Available This qualitative research study explored the work experience in a call centre environment in an information technology call centre based in South Africa, which service foreign customers exclusively. Three data collection methods were used, namely narratives, in-depth interviews with call centre consultants, and observation. Following a grounded theory approach, four themes were elicited, namely the perceptions of team members, uncertainty created by a constantly changing environment, perceived distances due to management practices, and depersonalisation experienced while actually dealing with customers. In addition to this, the reported impact of these themes on work performance was explored and compared to existing research.

  19. CWTC business plan; Wind turbine component centre

    Energy Technology Data Exchange (ETDEWEB)

    Hjuler Jensen, P.; Hillestroem, A.; Markou, H.; Berring, P.; Friis, P.

    2011-04-15

    This report presents the Business Plan for the establishment of the Wind Turbine Component Centre (CWTC) to meet the objectives of performing theoretical research and experimental testing. The core idea of a CWTC is to support the Danish wind energy industry and research activities at the component level improving the competitive advantage of that industry. The CWTC will in itself operate its activities, including access to test and experimental facilities, on a semi commercial basis. The business model for the CWTC presented is based on revenues coming from component manufacturers as well as research grants, and will include membership fees as well as hourly payment and larger projects where payment is a limited project sum. The presented roadmap model clarifies the development path towards a fully developed CWTC, which will cover test of all important components along the drive-train as well as offering a comprehensive systematic understanding of the entire drive-train. The CWTC will over time market and sell its products and services on a global scale, but first and foremost the CWTC is established to support and strengthen the Danish wind energy industry and specifically the Danish sub suppliers to the Danish wind turbine industry and also the Danish research establishments. The presented organizational structure reflects that there are certain functions that are separated from the operations and it also reflects that scientific staffing are hired in on a project basis. Machine operators will be hired in on a permanent basis. The breakdown of the cost for running the rig, both for R and D and commercial projects is presented. The income from the other activities is calculated based on the cost for the research staff, both for R and D activities and commercial. In the first year the income will be 100% from R and D activities, which is the cost for the staff to set-up the test-rig, the guidelines and test procedures, and partly for running the rig. Within 3

  20. Upgrade Opportunities for Buildings in City Centres

    Directory of Open Access Journals (Sweden)

    Silva M.

    2012-10-01

    Full Text Available This proposal focus on the potential of the existing buildings upgrade process in achieving the 20-20-20 goals, as these are the biggest energy consumers, the most significant built area and the better placed buildings within our cities. These buildings frequently lack basic maintenance and need intervention, but include within themselves a vast amount of incorporated energy and centuries of construction knowledge. Beyond the advantages that may result from re-attracting people back into the city centre, upgrading these existing buildings can also have positive bounce-back effect on the reduction of the energy needs related to transportation, as demonstrated in studies that alert to the impact of the building sprawl in the total energy use. As “buildings account for 40 % of total energy consumption in the Union”, the better performance of this sector has a significant role, remembering that “these requirements shall take account of general indoor climate conditions, in order to avoid possible negative effects such as inadequate ventilation, as well as local conditions and the designated function and the age of the building” [1]. The importance of “upgrading” the existing buildings resides on the fact that new buildings represent only approximately 1 or 2% of the total usable area, an estimate that is bound to decrease due to the current construction crisis. While the recent buildings tend to be more efficient, the numerous existing buildings are important stakeholders due to their massive consumptions and incorporated energy. The ongoing Annex 56 on “Energy & Greenhouse Gas Optimized Building Renovation” assumes that “Current standards do not respond effectively to the numerous constraints imposed by existing buildings and in many cases, the requirements result in very expensive measures and complex procedures, seldom accepted by occupants, owners or developers. It is then urgent for the new standards to respond to these

  1. Visualization in a Climate Computing Centre

    Science.gov (United States)

    Meier-Fleischer, Karin; Röber, Niklas; Böttinger, Michael

    2014-05-01

    Today, the extensive numerical simulations of climate models require elaborate visualization for understanding and communicating the results. Typical data sets of climate models are 3-dimensional, multivariate and time dependent, and can hence be very large. Interactive visual data analysis improves and accelerates the comprehension of these vast amounts of data. At DKRZ, the German Climate Computing Centre, a central high end visualization server, various domain specific visualization applications, and a remote 3D rendering solution enable users to interactively visualize their extensive model results right at their desktops. The DKRZ's visualization server is a heterogeneous Linux cluster, currently consisting of 10 state of the art visualization nodes equipped with 96 -256 GB RAM and high end NVidia GPUs. Since the parallel file system of the DKRZ's supercomputer is directly mounted over a powerful network, the model data can directly be analyzed and visualized. VirtualGL and TurboVNC are used for utilizing the server's GPUs for 3D rendering, while the TurboVNC client on the user's local computer continuously displays the resulting video stream. By using this central visualization server instead of a local computer, three main benefits are achieved: Time consuming transfers of large data sets from the supercomputer to the local computer are not needed. The hardware of the user's local workstation doesn't need to be powerful, no expensive GPU is required. Users don't have to install or buy visualization software. On the visualization server, a wide range of visualization software is installed. Avizo Green, a powerful commercial software customized for interactive 3D visualization of climate model data, is available, as well as SimVis and ParaView, which focus more on an exploratory visualization of data. SimVis and ParaView provide techniques like Linking & Brushing to emphasize or de-emphasize portions of the data. Furthermore, some domain specific 2D graphics

  2. Target preparation at the ANTARES AMS Centre

    Energy Technology Data Exchange (ETDEWEB)

    Jacobsen, G.E.; Hua, Q.; Fink, D.; Hotchkis, M.A.C.; Lawson, E.M. [Australian Nuclear Science and Technology Organisation, Lucas Heights, NSW (Australia)

    1996-12-31

    The Antares Accelerator Mass Spectroscopy Centre at ANSTO has two chemistry labs dedicated to preparing targets for measurement. Target preparation encompasses a variety of activities ranging from the curation of incoming samples to the numerous steps involved in the purification and processing of dissimilar samples. One of the two laboratories is set up for the physical and chemical pretreatment of {sup 14}C samples. Treatments include cleaning by sonification, sorting, grinding and sieving, and chemical treatments such as the standard AAA treatment, and solvent extraction. Combustion and graphitization are also carried out in this laboratory. The second laboratory is a clean room and is dedicated to the combustion, hydrolysis and graphitization of {sup 14}C samples as well as the process of the targets for the other isotopes. Combustion is achieved by heating the sample to 900 deg C in the presence of CuO, the resulting gas is purified by passing over Ag and Cu wire at 600 deg C. Graphitization is carried out by reducing the CO{sub 2} with an iron catalyst (600 deg C) in the presence of zinc (400 deg C) and a small amount of hydrogen. Samples such as charcoal, shell bone, wood, sediment, seawater and groundwater, containing 0.3-1 mg or more of original carbon, are processed routinely for radiocarbon analysis. The current {sup 14}C chemistry background for 1 mg carbon is {approx} 0.3 percent of modern carbon (pMC) enabling us to date materials up to 45 000 BP. Samples of 0.5 - 3 mg carbon or more are routinely performed with a precision < 1% At present, procedures are being tested for the treatment of samples containing a minimum of 20 {mu}g original carbon. Such small samples sre more likely to be affected by contamination with modern carbon. These laboratories are also being expanded to cater for the processing of a variety of samples for the measurement of other isotopes, ie {sup 129}I, {sup 10}Be, {sup 36}CI and {sup 26}Al. Initial tests for the extraction of

  3. Tunnel-coupled quantum dots: Atomistic Theory of Quantum Dot Molecules and Arrays

    Science.gov (United States)

    Bryant, Garnett W.; Aizpurua, J.; Jaskolski, W.; Zielinski, Michal

    2003-03-01

    Quantum dots are studied as artificial atoms for building novel artificial solids, as nanodevices in nanoelectronics, and as bio/nanohybrids. We present an atomistic tight-binding theory of coupled CdS nanocrystals and vertically and laterally coupled InAs self-assembled dots. Electron states of coupled dots follow the analogy of coupled dots as artificial molecules. Symmetric/antisymmetric pairs are formed with strongest coupling between states with high density at interdot interfaces. Complex coupling of hole states, with significant departures from the artificial molecule analogy, occurs because the coupling is determined by the hole envelope function and the hole atomic state. Some hole states couple to form symmetric/antisymmetric pairs. Other hole states couple through additional intermediate states to form two strongly split symmetric states and an antisymmetric state insensitive to coupling. These coupling effects lead to level reordering, changes in state symmetry, conversion of dark states to bright states and vice versa, and tailored polarization dependence.

  4. Protein-lipid interactions in the purple bacterial reaction centre.

    Science.gov (United States)

    Jones, Michael R; Fyfe, Paul K; Roszak, Aleksander W; Isaacs, Neil W; Cogdell, Richard J

    2002-10-11

    The purple bacterial reaction centre uses the energy of sunlight to power energy-requiring reactions such as the synthesis of ATP. During the last 20 years, a combination of X-ray crystallography, spectroscopy and mutagenesis has provided a detailed insight into the mechanism of light energy transduction in the bacterial reaction centre. In recent years, structural techniques including X-ray crystallography and neutron scattering have also been used to examine the environment of the reaction centre. This mini-review focuses on recent studies of the surface of the reaction centre, and briefly discusses the importance of the specific protein-lipid interactions that have been resolved for integral membrane proteins.

  5. Enantiomeric resolution of multiple chiral centres racemates by capillary electrophoresis.

    Science.gov (United States)

    Ali, Imran; Suhail, Mohd; Al-Othman, Zeid A; Alwarthan, Abdulrahman; Aboul-Enein, Hassan Y

    2016-05-01

    Enantiomeric resolution of multichiral centre racemates is an important area as some multichiral centre racemates are of great medicinal importance. However, enantioseparation of such types of racemates is a challenging task. Amongst many analytical techniques, capillary electrophoresis is a powerful technique and may be used to resolve such racemates. Only few papers are available describing enantiomeric resolution of such racemates. Therefore, efforts have been made to describe the enantiomeric resolution of multichiral centre racemates by capillary electrophoresis. This article discusses the importance of multichiral racemates, the need for capillary electrophoresis in enantiomeric resolution and chiral resolution of multichiral centre racemates using various chiral selectors. Further, attempts have been made to discuss the future challenges and prospects of enantiomeric resolution of multichiral racemates. The various chiral selectors used for the purpose are chiral crown ether, cyclodextrins, polysaccharides, macrocyclic glycopeptide antibiotics and ligand exchange.

  6. Centre National d'enseignement à distance (CNED

    Directory of Open Access Journals (Sweden)

    Stefania Manca

    1996-01-01

    Full Text Available Presentation of the Centre National d'Enseignement a Distance "(CNED in France, a public institution with the aim of providing and promoting distance learning, especially through the modern communication techniques.

  7. The Visual Advice Centre, Eindhoven, The Netherlands. An intervenient evaluation.

    Science.gov (United States)

    Neve, J J; Korten, W E; Jorritsma, F F; Kinds, G F; Legein, C P

    1992-01-01

    On referral by ophthalmologists, the Visual Advice Centre provides the partially sighted with advice and prescriptions for illumination and visual aids. In this paper the multidisciplinary structure of the centre is presented and the results obtained in the first 18 months of its existence are discussed. Two hundred and ninety-eight patients were referred to the centre in this period. The majority of these patients (79.2%) were older than 60 years. The main cause of visual impairment was macular disease (45.3% of the patients). An interesting finding is that, although reading is an important need, reading problems only constituted 35.9% of the total number of demands for help. From an inquiry into the situation of 125 patients 6 months after prescription, it appears that more than 90% of the aids prescribed are used regularly. The conclusion is drawn that patients referred to the Visual Advice Centre benefit from the multi-disciplinary approach to their problems.

  8. Nano-engineered pinning centres in YBCO superconducting films

    Science.gov (United States)

    Crisan, A.; Dang, V. S.; Mikheenko, P.

    2017-02-01

    For practical applications of superconducting materials in applied magnetic fields, artificial pinning centres in addition to natural ones are required to oppose the Lorentz force. These pinning centres are actually various types of defects in the superconductor matrix. The pinning centres can be categorised on their dimension (volume, surface or point) and on their character (normal cores or Δκ cores). Different samples have been produced by Pulsed Laser Deposition, with various thicknesses, temperatures and nanostructured additions to the superconducting matrix. They have been characterized by SQUID Magnetic Properties Measurement System and Physical Properties Measurement System, as well as by Transmission Electron Microscopy (TEM). Correlations between pinning architecture, TEM images, and critical currents at various fields and field orientations will be shown for a large number of YBa2Cu3Ox films with various types and architectures of artificial pinning centres.

  9. Dynamic analysis of house price diffusion across Asian financial centres

    OpenAIRE

    Nanda, Anupam; Yeh, Jia-Huey

    2012-01-01

    The aim of this paper is to explore effects of macroeconomic variables on house prices and also, the lead-lag relationships of real estate markets to examine house price diffusion across Asian financial centres. The analysis is based on the Global Vector Auto-Regression (GVAR) model estimated using quarterly data for six Asian financial centres (Hong Kong, Tokyo, Seoul, Singapore, Taipei and Bangkok) from 1991Q1 to 2011Q2. The empirical results indicate that the global economic conditions pla...

  10. Student centred teaching methods in a Chinese setting.

    Science.gov (United States)

    Clarke, Janice

    2010-01-01

    This paper offers a discussion about using Western, student centred teaching methods with Chinese student nurses. There is increasing interest from Chinese nurse educators in student centred learning and an increase in partnerships between Chinese and Western universities. This paper suggests that the assumption that Western teaching methods are superior is now questioned and transferring Western style teaching to China requires a high degree of cultural sensitivity.

  11. How to do a person-centred eye health consultation

    Directory of Open Access Journals (Sweden)

    Renée du Toit

    2015-09-01

    Full Text Available The care we give should focus on our patients – their needs, beliefs, and preferences – and not just on their disease. This is known as patient-centred care. We can take this idea further and talk about person-centred care, which reminds us that we should be concerned with the whole person – and their life – when they are outside of the clinic too, not just when they are in front of us.

  12. Fast synthesize ZnO quantum dots via ultrasonic method.

    Science.gov (United States)

    Yang, Weimin; Zhang, Bing; Ding, Nan; Ding, Wenhao; Wang, Lixi; Yu, Mingxun; Zhang, Qitu

    2016-05-01

    Green emission ZnO quantum dots were synthesized by an ultrasonic sol-gel method. The ZnO quantum dots were synthesized in various ultrasonic temperature and time. Photoluminescence properties of these ZnO quantum dots were measured. Time-resolved photoluminescence decay spectra were also taken to discover the change of defects amount during the reaction. Both ultrasonic temperature and time could affect the type and amount of defects in ZnO quantum dots. Total defects of ZnO quantum dots decreased with the increasing of ultrasonic temperature and time. The dangling bonds defects disappeared faster than the optical defects. Types of optical defects first changed from oxygen interstitial defects to oxygen vacancy and zinc interstitial defects. Then transformed back to oxygen interstitial defects again. The sizes of ZnO quantum dots would be controlled by both ultrasonic temperature and time as well. That is, with the increasing of ultrasonic temperature and time, the sizes of ZnO quantum dots first decreased then increased. Moreover, concentrated raw materials solution brought larger sizes and more optical defects of ZnO quantum dots.

  13. Single-photon superradiance from a quantum dot

    DEFF Research Database (Denmark)

    Tighineanu, Petru; Daveau, Raphaël Sura; Lehmann, Tau Bernstorff

    2016-01-01

    We report on the observation of single-photon superradiance from an exciton in a semiconductor quantum dot. The confinement by the quantum dot is strong enough for it to mimic a two-level atom, yet sufficiently weak to ensure superradiance. The electrostatic interaction between the electron and t...

  14. A Nanowire-Based Plasmonic Quantum Dot Laser.

    Science.gov (United States)

    Ho, Jinfa; Tatebayashi, Jun; Sergent, Sylvain; Fong, Chee Fai; Ota, Yasutomo; Iwamoto, Satoshi; Arakawa, Yasuhiko

    2016-04-13

    Quantum dots enable strong carrier confinement and exhibit a delta-function like density of states, offering significant improvements to laser performance and high-temperature stability when used as a gain medium. However, quantum dot lasers have been limited to photonic cavities that are diffraction-limited and further miniaturization to meet the demands of nanophotonic-electronic integration applications is challenging based on existing designs. Here we introduce the first quantum dot-based plasmonic laser to reduce the cross-sectional area of nanowire quantum dot lasers below the cutoff limit of photonic modes while maintaining the length in the order of the lasing wavelength. Metal organic chemical vapor deposition grown GaAs-AlGaAs core-shell nanowires containing InGaAs quantum dot stacks are placed directly on a silver film, and lasing was observed from single nanowires originating from the InGaAs quantum dot emission into the low-loss higher order plasmonic mode. Lasing threshold pump fluences as low as ∼120 μJ/cm(2) was observed at 7 K, and lasing was observed up to 125 K. Temperature stability from the quantum dot gain, leading to a high characteristic temperature was demonstrated. These results indicate that high-performance, miniaturized quantum dot lasers can be realized with plasmonics.

  15. Exciton dephasing in single InGaAs quantum dots

    DEFF Research Database (Denmark)

    Leosson, Kristjan; Østergaard, John Erland; Jensen, Jacob Riis;

    2000-01-01

    . The homogeneous and inhomogeneous broadening of InGaAs quantum dot luminescence is of central importance for the potential application of this material system in optoelectronic devices. Recent measurements of MOCVD-grown InAs/InGaAs quantum dots indicate a large homogeneous broadening at room temperature due...

  16. Teaching Beginning Chemistry Students Simple Lewis Dot Structures

    Science.gov (United States)

    Nassiff, Peter; Czerwinski, Wendy A.

    2015-01-01

    Students beginning their initial study of chemistry often have a difficult time mastering simple Lewis dot structures. Textbooks show students how to manipulate Lewis structures by moving valence electron dots around the chemical structure so each atom has an octet or duet. However, an easier method of teaching Lewis structures for simple…

  17. Electron Energy Level Statistics in Graphene Quantum Dots

    NARCIS (Netherlands)

    De Raedt, H.; Katsnellson, M. I.; Katsnelson, M.I.

    2008-01-01

    Motivated by recent experimental observations of size quantization of electron energy levels in graphene quantum dots [7] we investigate the level statistics in the simplest tight-binding model for different dot shapes by computer simulation. The results are in a reasonable agreement with the experi

  18. 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 deta...

  19. Negative Trions Trapped by a Spherical Parabolic Quantum Dot

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    In this paper, a negatively charged exciton trapped by a spherical parabolic quantum dot has been investigated. The energy spectra of low-lying states are calculated by means of matrix diagonalization. The important feature of the low-lying states of the negatively charged excitons in a spherical quantum dot is obtained via an analysis of the energy spectra.

  20. 49 CFR 41.119 - DOT regulated buildings.

    Science.gov (United States)

    2010-10-01

    ... and additions to existing buildings will ensure that each DOT regulated building is designed and... section pertains to all new building projects for which development of detailed plans and specifications.... (d) For DOT regulated buildings a certification of compliance with the seismic design...