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1.
Unsteady motion in single-line flow-injection systems consisting of n tubular elements with valve or hydrodynamic injection is studied theoretically. A formula for the duration of the initial period of unsteady flow is derived. This initial period is much shorter than the mean residence time of the analyte in practical systems. It can therefore be neglected in mathematical modelling of such systems. Experimental data obtained with single-line systems with valve and hydrodynamic injection confirmed the validity of the theoretical equations. 相似文献
2.
Y. A. Coutinho J. A. Martins Simões C. M. Porto 《Zeitschrift fur Physik C Particles and Fields》1997,73(4):705-709
In this paper we investigate the effects of heavy Majorana neutrinos in the reaction e + e ? → W + W ?. We consider neutrino masses in the 1–10 TeV region. We show that at LEP II and NLC energies it is possible to use this processes to verify indirect evidence of heavy neutral particles with mixing angles of the order sin2 α = 0.01. We discuss the unitarity restrictions that can be obtained for vector singlet and fermion-mirror-fermion models. 相似文献
3.
We describe a general method that enables us to obtain all the singular terms of helicity amplitudes of n-parton processes at one loop. The algorithm uses helicity amplitudes at tree level and simple color algebra. We illustrate the method by calculating the singular part of the one-loop helicity amplitudes of all 2 → 3 parton subprocesses. The results are used to derive the soft gluon limit of the cross sections of all 2 → 4 parton scattering subprocesses which provide a useful initial condition for the angular ordering approximation to coherent multiple soft gluon emission, incorporated in existing Monte Carlo simulation programs. 相似文献
4.
Let λ and μ be solid sequence spaces. For a sequence of modulus functions Φ = (ϕ k) let λ(Φ) = {x = (x
k
): (ϕk(|x
k
|)) ∈ λ}. Given another sequence of modulus functions Ψ = (ψk), we characterize the continuity of the superposition operators P
f
from λ(Φ) into μ (Ψ) for some Banach sequence spaces λ and μ under the assumptions that the moduli ϕk (k ∈ ℕ) are unbounded and the topologies on the sequence spaces λ(Φ) and μ(Ψ) are given by certain F-norms. As applications
we consider superposition operators on some multiplier sequence spaces of Maddox type.
This research was supported by Estonian Science Foundation Grant 5376. 相似文献
5.
A two-dimensional framework (G,p) is
a graph G = (V,E) together with a map p: V → ℝ2. We view (G,p) as a straight line realization of G in ℝ2. Two realizations of G are equivalent if the corresponding edges in the two frameworks have the same length.
A pair of vertices {u,v} is globally linked in G if %and for all equivalent frameworks (G,q), the distance between the points
corresponding to u and v is the same
in all pairs of equivalent generic realizations of G. The graph G is globally rigid
if all of its pairs of vertices are globally linked. We extend the characterization of globally rigid graphs given by the
first two authors [13] by characterizing globally linked pairs in M-connected graphs, an important family of rigid graphs.
As a byproduct we simplify the proof of a result of Connelly [6] which is a key step in the characterization of globally rigid
graphs. We also determine the number of distinct realizations of an M-connected graph, each of which is equivalent to a given
generic realization. Bounds on this number for minimally rigid graphs were obtained by Borcea and Streinu in [3]. 相似文献
6.
7.
Theoretical concerns about the use of cemented and press-fit stems in revision total knee arthroplasty (TKA) include stress
shielding with adverse effects on prosthesis fixation. Radiological studies have showed distal femoral bone resorption after
revision TKA. The revision with use of stems can place abnormal stresses. These stresses can promote the effect of bone stress
shielding and may contribute to bone loss. Experimental quantification of strain shielding in the distal synthetic femur following
TKA is the main purpose of the present study. Three different constructs of TKA were assessed. The first construct included
a stemless femoral component. The other two included a press-fit and a cemented femoral stem. Cortical bone strains were measured
experimentally with tri-axial strain gauges in synthetic femurs before and after in-vitro knee surgery. The difference between
principal strains of implanted and intact femur was calculated for each strain gauge position. This study indicates that the
use of stems in distal femur changes the distribution and magnitude of bone strains. The press-fit stem provoked relevant
bone area (stem length) subjected to strain shielding and also originated the highest reduction of strains in the distal region,
which can potentially induce bone resorption. The stemless implanted femur produced minor bone strain changes relatively to
the intact femur. The use of distal femur stems increases initial stability in the bone, but the observed reduction of strains
in this region, relative to the intact femur, provokes strain shielding that can induce bone resorption and may compromise
the long term implant stability. 相似文献
8.
Ferenc Sztaricskai Gyula Batta Zoltan Dinya Istvan F. Pelyvas Pal Herczegh Tamas E. Gunda Istvan Koczka 《Chemistry of Heterocyclic Compounds》1998,34(11):1296-1307
Starting from 3,5-dimethylisoxazole the carboxylic acids I and V, the amino acids VIII (L-) and IX (D-), and the ureido acids X (L-) and XI (D-) were prepared, which were used for the synthesis of the new cephalosporins XVIIb, XXa-c (L-), and XXIb (D-). Thein vitro antibacterial activity of these semi-synthetic antibiotics was studied. The resorption of XVIIb was investigated in mice.Research Group for Antibiotics of the Hungarian Academy of Sciences, H-4010 Debrecen, P.O. Box 70, Hungary. Published in Khimiya Geterotsiklicheskikh Soedinenii, No. 11, pp. 1524–1535, November, 1998. 相似文献
9.
The aim of this research work was to clarify the role of the mixed emulsifier in the structure formation and water binding
mode in the case of o/w creams prepared with different surfactants. The swelling behavior of mixed emulsifiers was examined
by means of direct investigation methods such as transmission electron microscopy (TEM) and X-ray diffraction. The detailed
structure image of the creams was created with the help of the latter. The influence of the structure of the hydrophilic gel
phase, and the structural changes during storage were studied with rheological methods. On the basis of the results, it can
be stated that the investigated creams had different structures from those mentioned in the literature: surfactant did not
create a mixed bilayer with the structure to furnish fatty amphiphile; instead, micelles were formed. These results correlated
well with the results of the rheological tests. 相似文献
10.
WO3 and WO3:P (5 mol% H3PO4) thin films were prepared using the sol-gel route and the electrochromic properties of the films were investigated using
in situ spectroelectrochemical methods. The measurements were performed in propylene carbonate solution with 0.1 M LiClO4 as electrolyte. During the cathodic polarization at –0.8 V a blue coloration is observed with a reversible variation between
14% and 84% of the transmittance at λ=633 nm. The kinetics for the bleaching process is faster for the WO3:P film than for the undoped WO3 film.
Electronic Publication 相似文献