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71.
Benjamin Byerly Kevin Kuhn Lisa Colletti Lynn Foster Russ Keller Elmer Lujan Alex Martinez Donivan Porterfield Dan Schwartz Khal Spencer Floyd Stanley Mariam Thomas Lisa Townsend Ning Xu Lav Tandon 《Journal of Radioanalytical and Nuclear Chemistry》2017,312(1):95-104
Thorough physical and chemical characterization of plutonium–beryllium (PuBe) neutron sources is an important capability with applications ranging from material accountancy to nuclear forensics. Characterization of PuBe sources is not trivial owing to range of existing source designs and the need for adequate infrastructure to deal with radiation and protect the analyst. This study demonstrates a method for characterization of three PuBe sources that includes physical inspection and imaging followed by controlled disassembly and destructive analysis. 相似文献
72.
J. M. Martinez C. Volzone L. B. Garrido 《Journal of Thermal Analysis and Calorimetry》2017,128(1):61-69
Aluminum-pillared montmorillonites are useful materials for their application as catalysts, adsorbents and ceramic composites. The precursor is a pillared montmorillonite that is not thermally stabilized. The precursor preparation methods, textural properties and catalytic activity have been extensively investigated, but comparatively, studies concerning their thermal transformations at high temperature are limited. In this work, precursors were prepared using two types of montmorillonites, Cheto (Ch) and Wyoming (W), and using two different OH–Al polymer sources: hydrolyzed (H) and commercial (C) solutions. Structural and thermal transformations of the precursors with heating up to 1200 °C were determined by X-ray diffraction and thermogravimetric analysis. Thermal analysis of these precursors below 600 °C revealed the influence of OH–Al polymers from the two solutions. The major phases developed at 1200 °C from the original montmorillonites were mullite for W and cordierite for Ch. The content of these phases depended on the aluminum in the octahedral sheet of the pristine montmorillonites. Amorphous phase, cristobalite, spinel, sapphirine and others phases were also found. The intercalation of OH–Al polymers in montmorillonites caused an increase in amorphous content after treatment at 1030 °C; however, it favored mullite development above 1100 °C. Although total aluminum content of both W and Ch precursors was similar, the transformation to mullite was directly related to the octahedral aluminum/magnesium ratio. The phase composition of the products at 1200 °C was not dependent on the type of intercalated OH–Al polymers. The increase in mullite content of the thermally treated precursors contributes to its possible application as advanced ceramic products. 相似文献
73.
74.
L.M. León M.C. Gonzalez J.R. Quintana F. Zamora Armando Martinez G.M. Guzman 《European Polymer Journal》1982,18(3):229-231
The Ptitsyn-Eizner λ flexibility parameter for poly(N-vinylcarbozole) solutions under theta conditions has been found to be 6.31, demonstrating the rigidity imparted to the polymer chain by the carbazole group. A study has been made of the variation of this parameter with solvent and temperature. A study has been made of the variation of λ in a conformational transition of poly(methyl methacrylate). 相似文献
75.
F. Bosch Reig V. Peris Martinez F. Bosch Mossi J. V. Gimeno Adelantado 《Fresenius' Journal of Analytical Chemistry》1992,342(4-5):295-298
Summary An algorithm for quantifying interelemental effects in X-ray fluorescence techniques is developed. By applying an addition process, the ratio between the mass absorption coefficients of the analyte and the unknown sample (
i
*
/
s
*
) is calculated to correct the fluorescence intensity of the element to be determined and linearize the I-c calibration plot. This coefficient can be calculated graphically and numerically. The method is applied to the determination of tin in lead alloys with good results over wide concentration ranges.Notation used Q
Constant of proportionality in Eq. (4)
X-ray fluorescence intensity of the I
i
o
standard
- I
i
s
unknown sample
- I
i
ns
dilute unknown sample
- I
i
ms
unknown sample after addition of i analyte
Corrected fluorescence intensity of the I
i
cs
unknown sample
- I
i
msc
unknown sample after addition of i analyte
Relationship of fluorescence intensity between Ri
sample and standard
- R
i
dilute sample and standard
Factor of fm
addition
- fx
addition equivalent to the mass fraction of the i analyte in the unknown sample
Mass absorption coefficient of
i
*
analyte
-
s
*
unknown sample
-
ms
*
unknown sample after addition
Mass fraction of c
i
s
analyte
- c
i
ms
unknown sample after addition 相似文献
76.
J. Martinez Calatayud S. Navasquillo Sarrion A. Sanchez Sampedro C. Gomez Benito 《Microchemical Journal》1992,45(2)
A flow injection analysis procedure for the turbidimetric determination of promethazine is proposed. The sample solution is injected directly into the carrier reagent stream, which is composed of 1.16 × 10−3M bromophenol blue at pH 1.20. The calibration graph is linear over the range 25–197 ppm of promethazine. The influence of some foreign substances was also investigated. The method is applied to promethazine determination in a pharmaceutical formulation. 相似文献
77.
Thode A Mellinger DK Stienessen S Martinez A Mullin K 《The Journal of the Acoustical Society of America》2002,112(1):308-321
Three-dimensional dive trajectories of three sperm whales in the Gulf of Mexico have been obtained by measuring the relative arrival times and bearings of the animals' acoustic multipath reflections, using two elements of a towed hydrophone array deployed at an unknown depth and orientation. Within the first 6-12 min of the start of a dive, the intervals between successive "clicks" of all three whales corresponded closely with the two-way travel time of an acoustic pulse traveling vertically between the animals' position and the ocean bottom. The click spectra contained multiple peaks, including a faint band of energy originally centered near 10 kHz. As the animals descended over 500 m in depth, the center frequency of this band shifted to nearly 15 kHz, but subsequently remained near this value during the rest of the dive. This frequency shift is consistent with that expected from energy scattering from an ensemble of incompressible small-scale air-filled resonators, with diameters on the order of 4 mm. One possible candidate for such an ensemble is proposed to reside in the collapsed frontal sac of the animal. A comparison of the received levels for the bottom and direct multipath arrivals indicates that the whales' acoustic directivity must range between 10-30 dB in the 5-20-kHz region. 相似文献
78.
Farrington EJ Martinez Viviente E Williams BS van Koten G Brown JM 《Chemical communications (Cambridge, England)》2002,(4):308-309
The 1,3-bis(diphosphinomethyl)ferrocene 3 readily reacts with [(C2H4)2RhCl]2 to form an equilibrating pair of diastereomers 8a and 8b by C-H insertion into the ferrocene. 相似文献
79.
C. Andreoiu M. Axiotis G. de Angelis J. Ekman C. Fahlander E. Farnea A. Gadea T. Kröll S.M. Lenzi N. Mărginean T. Martinez M.N. Mineva C. Rossi Alvarez D. Rudolph C.A. Ur 《The European Physical Journal A - Hadrons and Nuclei》2002,15(4):459-462
Excited states in 59Zn were observed for the first time following the fusion-evaporation reaction 24Mg + 40Ca at a beam energy of 60 MeV. The GASP array in conjunction with the ISIS Silicon ball and the NeutronRing allowed for the
detection of γ-rays in coincidence with evaporated light particles. The mirror symmetry of 59Zn and 59Cu is discussed.
Received: 28 May 2002 / Accepted: 10 July 2002 / Published online: 3 December 2002
RID="a"
ID="a"Present address: Oliver Lodge Laboratory, University of Liverpool, P.O. Box 147, Liverpool, L69 7ZE, United Kingdom; e-mail: ca@ns.ph.liv.ac.uk.
RID="b"
ID="b"Present address: Physik-Departament, Technische Universit?t München, D-85748 Garching, Germany.
Communicated by W. Henning 相似文献
80.
Extreme Estimates for Interpolated Operators by the Real Method 总被引:3,自引:0,他引:3
The paper establishes estimates for ideal measures of operatorsinterpolated by the real method in terms of the measures oftheir restrictions to a sequence of spaces modelled on the intersection.It also shows that the estimates are optimal. 相似文献