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141.
Farruh Mukhamedov Seyit Temir Hasan Akin 《Proceedings of the American Mathematical Society》2006,134(3):843-850
Akcoglu and Suchaston proved the following result: Let be a positive contraction. Assume that for the sequence converges weakly in . Then either or there exists a positive function , such that . In the paper we prove an extension of this result in a finite von Neumann algebra setting, and as a consequence we obtain that if a positive contraction of a noncommutative -space has no nonzero positive invariant element, then its mixing property implies the completely mixing property.
142.
Of the five small biradicaloid heterocycles whose S(1), S(2), T(1), and T(2) adiabatic excitation energies were examined by the CASPT2/ANO-L-VTZP method, two have been found to meet the state energy criterion for efficient singlet fission and are recommended to the attention of synthetic chemists and photophysicists. 相似文献
143.
Algin O Ozmen E Metin MR Ozcan MF Sivaslioglu AA Karaoglanoglu M 《Magnetic resonance imaging》2012,30(5):734-739
Urinary fistulas and leakages of lower urinary tract are serious complications of various surgical procedures. Radiologists need to have enough information about these situations to perform precise diagnosis and treatment. Various techniques [such as intravenous pyelography, ultrasound, computed tomography (CT), CT urography, cystoscopy, cystography and magnetic resonance (MR) imaging] are used for the diagnosis of these conditions. Application of all these techniques reduces the comfort and cooperation of the patients and increases the cost. Here we present four postoperative patients with lower urinary tract fistula or leakage. To the best of our knowledge, there is no report regarding the use of contrast-material-enhanced MR urography (CE-MRU) in the demonstration of postoperative lower urinary tract fistulae and leakages. In conclusion, CE-MRU could show the existence and location of the urinary fistulae and leakages clearly without the need for another investigation technique, as described in our patients. Also, CE-MRU is a safe and relatively inexpensive technique that avoids exposure to radiation as well as nephrotoxic and more allergic contrast-material administration. 相似文献
144.
The mercury complex of 2,6-bis(3,5-dimethyl-N-pyrazolyl)pyridine (bdmpp) has been synthesized and characterized by X-ray diffraction, IR, UV–Vis and TGA–DTA methods. The structure consists of units in which the mercury atom is pentacoordinate with two sulfur and three nitrogen atoms. [Hg(bdmpp)(SCN)2] has a distorted square pyramid geometry. 相似文献
145.
A. Nilgün Akin Mustafa Ataman A. Erhan Aksoylu Z. Ilsen Önsan 《Reaction Kinetics and Catalysis Letters》2002,76(2):265-270
CO2 fixation by hydrogenation over coprecipitated 36 wt.% Co/Al2O3 has been studied under a range of reaction conditions to clarify the effects of reaction variables and to determine the kinetics and mechanism of the reaction. A comparison of the results with those reported for CO hydrogenation on the same catalyst indicates that, although product distributions of CO2 and CO hydrogenation differ, the kinetics and mechanism are similar. 相似文献
146.
The reaction of etheral methyllithium with 3,3-dibromo-2,7,7-trimethyl-tricyclo[4.1.1.0(2,4)]octane (2) was investigated. The generated carbene 12 undergoes intramolecular C-H insertion to provide the tetracyclic hydrocarbon 3 and the bicyclic allene 15, which undergoes [2+2] cyclodimerization. The structures of the formed allene dimers 16, 17, and 18 were elucidated by spectral means. The activation barriers for all possible C-H insertion products 3, 13, and 14 and the allene 15 were investigated by using density functional theory computations at the B3LYP/6-31G(d) level. It was found that the activation barriers for the formation of 3 and 15 (6.2 and 6.3 kcal mol(-1)) are much lower than that for the insertion products 13 and 14 (17.5 and 12.6 kcal mol(-1)), respectively. This prediction was completely in agreement with our experimental results. 相似文献
147.
We study the phase diagram for Potts model on a Cayley tree with competing nearest-neighbor interactions J
1, prolonged next-nearest-neighbor interactions J
p
and one-level next-nearest-neighbor interactions J
o
. Vannimenus proved that the phase diagram of Ising model with J
o
=0 contains a modulated phase, as found for similar models on periodic lattices, but the multicritical Lifshitz point is at
zero temperature. Later Mariz et al. generalized this result for Ising model with J
o
≠0 and recently Ganikhodjaev et al. proved similar result for the three-state Potts model with J
o
=0. We consider Potts model with J
o
≠0 and show that for some values of J
o
the multicritical Lifshitz point be at non-zero temperature. We also prove that as soon as the same-level interactionJ
o
is nonzero, the paramagnetic phase found at high temperatures for J
o
=0 disappears, while Ising model does not obtain such property. To perform this study, an iterative scheme similar to that
appearing in real space renormalization group frameworks is established; it recovers, as particular case, previous work by
Ganikhodjaev et al. for J
o
=0. At vanishing temperature, the phase diagram is fully determined for all values and signs of J
1,J
p
and J
o
. At finite temperatures several interesting features are exhibited for typical values of J
o
/J
1. 相似文献
148.
Residual properties and almost equicontinuity 总被引:3,自引:0,他引:3
A propertyP of a compact dynamical system (X,f) is called a residual property if it is inherited by factors, almost one-to-one lifts and surjective inverse limits. Many
transitivity properties are residual. Weak disjointness from all propertyP systems is a residual property providedP is a residual property stronger than transitivity. Here two systems are weakly disjoint when their product is transitive.
Our main result says that for an almost equicontinuous system (X, f) with associated monothetic group Λ, (X, f) is weakly disjoint from allP systems iff the onlyP systems upon which Λ acts are trivial. We use this to prove that every monothetic group has an action which is weak mixing
and topologically ergodic. 相似文献
149.
Although there are a number of mathematical modeling studies for carbon dioxide (CO2) injection into aquifer formations, experimental studies are limited and most studies focus on injection into sandstone reservoirs
as opposed to carbonate ones. This study presents the results of computerized tomography (CT) monitored laboratory experiments
to analyze permeability and porosity changes as well as to characterize relevant chemical reactions associated with injection
and storage of CO2 in carbonate formations. CT monitored experiments are designed to model fast near well bore flow and slow reservoir flows.
Highly heterogeneous cores drilled from a carbonate aquifer formation located in South East Turkey were used during the experiments.
Porosity changes along the core plugs and the corresponding permeability changes are reported for different CO2 injection rates and different salt concentrations of formation water. It was observed that either a permeability increase
or a permeability reduction can be obtained. The trend of change in rock properties is very case dependent because it is related
to distribution of pores, brine composition and thermodynamic conditions. As the salt concentration decreases, porosity and
the permeability decreases are less pronounced. Calcite deposition is mainly influenced by orientation, with horizontal flow
resulting in larger calcite deposition compared to vertical flow. 相似文献
150.
Nickel complex of O, O'-dinonyldithiophosphoric acid was prepared and characterised. Solvent extraction of nickel dinonyldithiophosphate [Ni(DNDTP)2] from acidic aqueous solutions into different organic phases was investigated and concentration of nickel was determined spectrophotometrically. A simple and selective spectrophotometric method was developed and applied to sediment samples. 相似文献