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81.
P. P. Povinec M. K. Pham J. A. Sanchez-Cabeza G. Barci-Funel R. Bojanowski T. Boshkova W. C. Burnett F. Carvalho B. Chapeyron I. L. Cunha H. Dahlgaard N. Galabov L. K. Fifield J. Gastaud J. -J. Geering I. F. Gomez N. Green T. Hamilton F. L. Ibanez M. Ibn Majah M. John G. Kanisch T. C. Kenna M. Kloster M. Korun L. Liong Wee Kwong J. La Rosa S. -H. Lee I. Levy-Palomo M. Malatova Y. Maruo P. Mitchell I. V. Murciano R. Nelson A. Nouredine J. -S. Oh B. Oregioni G. Le Petit H. B. L. Pettersson A. Reineking P. A. Smedley A. Suckow T. D. B. van der Struijs P. I. Voors K. Yoshimizu E. Wyse 《Journal of Radioanalytical and Nuclear Chemistry》2007,273(2):383-393
A reference material designed for the determination of anthropogenic and natural radionuclides in sediment, IAEA-384 (Fangataufa
Lagoon sediment), is described and the results of certification are presented. The material has been certified for 8 radionuclides
(40K, 60Co, 155Eu, 230Th, 238U, 238Pu, 239+240Pu and 241Am). Information values are given for 12 radionuclides (90Sr, 137Cs, 210Pb (210Po), 226Ra, 228Ra, 232Th, 234U, 235U, 239Pu, 240Pu and 241Pu). Less reported radionuclides include 228Th, 236U, 239Np and 242Pu. The reference material may be used for quality management of radioanalytical laboratories engaged in the analysis of radionuclides
in the environment, as well as for the development and validation of analytical methods and for training purposes. The material
is available from IAEA in 100 g units.
Retired from IAEA in 2003. 相似文献
82.
L. Liong Wee Kwong J. J. La Rosa S. H. Lee P. P. Povinec 《Journal of Radioanalytical and Nuclear Chemistry》2001,248(3):751-755
Liquid scintillation spectrometry has become the most widespread method for quantitative analysis of low level -emitters in environmental samples. This technique has been applied in the measurements of 241Pu, 3H and 90Sr in seawater and sediment samples. 241Pu can be measured by direct analysis of an electrodeposited source using - discrimination or by extraction of electrodeposited plutonium into a liquid form compatible with scintillation cocktail. Sediment from Mururoa and Fangataufa atolls showed activities ranging from 18 to 44 Bq/kg. A sediment profile sampled around Bikini Atoll in 1997 showed 241Pu activities ranging from 0.3 to 30 Bq/kg. 3H activities in pore water sediment from Mururoa and Fangataufa atolls were of the order of 103 Bq/m3 which demonstrated its underground origin. 90Sr was measured in the presence of 90Y. The counting efficiency was 92.41.5% and the background 0.027±0.001 s-1. The average chemical recovery for 90Sr was 673%. 相似文献
83.
The catalytic, user-friendly phosphination and arsination of aryl halides and triflates by triphenylphosphine and triphenylarsine using palladium catalysts have provided a facile synthesis of functionalized aryl phosphines and arsines in neutral media. Modification of the cynaoarisne yielded optically active N, As ligands which will be screened in various asymmetric catalysis. 相似文献
84.
C. Droullé J. C. Adjizian J. M. Corcy A. Poynard F. Hui Tse Kwong G. Potron 《Fresenius' Journal of Analytical Chemistry》1984,317(6):747-748
Conclusion In clinical states, we did not found any correlation between the techniques using these two viscometers which appear complementary; probably in erythrocyte dysfunction, they allow a better approach of the environment and the influence, in some cases, of plasmatic factors upon erythrocyte deformability. From this point of view, we actually consider that different techniques are necessary to establish in vitro a schedule of rheological behavior.
Analyse von rheologischen Parametern: verschiedene Techniken相似文献
85.
Kwong FY Li YM Lam WH Qiu L Lee HW Yeung CH Chan KS Chan AS 《Chemistry (Weinheim an der Bergstrasse, Germany)》2005,11(13):3872-3880
An interesting rhodium-catalyzed asymmetric aqueous Pauson-Khand-type reaction was developed. A chiral atropisomeric dipyridyldiphosphane ligand was found to be highly effective in this system. This operationally simple protocol allows both catalyst and reactants to be handled under air without precautions. Various enynes were transformed to the corresponding bicyclic cyclopentenones in good yield and enantiomeric excess (up to 95 % ee). A study of the electronic effects of the enyne substrates revealed a correlation between the electronic properties of the substrates and the ee value obtained in the product of the Pauson-Khand-type reaction. A linear free-energy relationship was observed from a Hammett study. 相似文献
86.
C.Y. Kwong A.B. Djurišiĉ P.C. Chui L.S.M. Lam W.K. Chan 《Applied Physics A: Materials Science & Processing》2003,77(3-4):555-560
The devices investigated in this work consisted of an indium tin oxide (ITO)-coated glass substrate, phthalocyanine (Pc) layer and an aluminum electrode. The Schottky cell exhibits optimal performance with one ohmic and one barrier contact. The work function of the ITO film is typically around 4.5–4.8 eV, while the HOMO level of phthalocyanine films is typically around 5.2 eV. It is known that surface treatment of ITO can change its work function. We investigated various ITO surface treatments for improving the performance of phthalocyanine-based Schottky solar cells. We found that cells of ITO treated with HCl and UV ozone exhibited the best performance. Four different phthalocyanines (Pcs), namely nickel phthalocyanine (NiPc), copper phthalocyanine (CuPc), iron phthalocyanine (FePc) and cobalt phthalocyanine (CoPc) were investigated. A power conversion efficiency as high as 10% was achieved for the CuPc cell with monochromatic excitation at 632.8 nm, with a light intensity of 2.7 W/cm2. PACS 72.40.+w; 73.61.Ph 相似文献
87.
A.B. Djurišić C.Y. Kwong T.W. Lau E.H. Li Z.T. Liu H.S. Kwok L.S.M. Lam W.K. Chan 《Applied Physics A: Materials Science & Processing》2003,76(2):219-223
Optical functions of tris (8-hydroxyquinoline) aluminum (Alq3) have been studied in the spectral range from 1.55 eV to 5 eV using spectroscopic ellipsometry. The samples have been deposited
by thermal evaporation on glass substrates. Optical functions of Alq3 deposited on unheated substrates and on substrates kept at 100 °C have been determined. The optical functions have been modeled
using point-to-point fitting, with the conventional oscillator model and modified oscillator model. It has been found that
point-to-point fitting gives the best agreement with the experimental data, and that the modified oscillator model yields
better agreement with the experimental data than the conventional oscillator model.
Received: 3 September 2001 / Accepted: 22 March 2002 / Published online: 5 July 2002
RID="*"
ID="*"Corresponding author. Fax: +852-2559/8738, E-mail: dalek@eee.hku.hk 相似文献
88.
R.H Kwong 《Journal of Mathematical Analysis and Applications》1983,96(1):85-106
In infinite time quadratic control and stochastic filtering problems for linear delay systems, operator algebraic Riccati equations play a very important role. However, since these are abstract operator equations, it is very useful, in analyzing their structure, to be able to characterize the kernel functions associated with the solutions of the operator Riccati equations. The kernel functions are given by the unique solution of a set of coupled differential equations. By comparing these kernel equations with similar ones available in the literature, it is shown that this characterization result is somewhat stronger than previously known results. Possible extentions to systems with control, observation, as well as state delays are also pointed out. 相似文献
89.
Jonathan F Schonfeld Waikwok Kwong Jonathan L Rosner C Quigg H.B Thacker 《Annals of Physics》1980,128(1):1-28
The construction of reflectionless potentials supporting a prescribed spectrum of Schrödinger bound states is discussed and related to the inverse problem for confining potentials. A simple formula is derived for the Jost solution in a one-dimensional reflection-less potential with N bound states. This leads to compact expressions for the potential and the bound-state wavefunctions in terms of the bound-state energies. For symmetric potentials, N-fold product formulas are obtained for bound-state wavefunctions and their slopes at the origin. Corresponding quantities in a confining potential are given by infinite products. Comparison of the finite-product and infinite-product expressions allows a demonstration of the convergence of the reflectionless results to the confining potential results as N → ∞. Several sum rules satisfied by the reflectionless potential at the origin are applied to numerical studies of convergence. 相似文献
90.
E. Eisenhandler W.R. Gibson C. Hojvat P.I.P. Kalmus L.C.Y.Lee Chi Kwong T.W. Pritchard E.C. Usher D.T. Williams M. Harrison W.H. Range M.A.R. Kemp A.D. Rush J.N. Woulds G.T.J. Arnison A. Astbury D.P. Jones A.S.L. Parsons 《Physics letters. [Part B]》1973,47(6):536-540
The differential cross-sections for p → π?π+ in the momentum range 0.8 to 2.4 GeV/c (centre-of-mass energy 2.02 to 2.57 GeV) are analysed in terms of the possible existence of s-channel resonances. The systematics of the dip structures and the s-dependence of dσ/dt are presented. 相似文献