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41.
Rafa? GrubbaAleksandra Wi?niewska Katarzyna BaranowskaEberhard Matern Jerzy Pikies 《Polyhedron》2011,30(7):1238-1243
Reactions of R2P-P(SiMe3)Li with [Cp2MCl2] (M = Zr, Hf) in hydrocarbons yield the related terminal phosphanylphosphido complexes [Cp2M(Cl){(Me3Si)P-PR2-κP1}] (R = iPr and tBu). The solid state structures of [Cp2M(Cl){P(SiMe3)-PiPr2-κP1}] (M = Zr, Hf) were established by single crystal X-ray diffraction studies. The phosphido-P atoms adopt almost planar geometries and the phosphanyl P atoms adopt pyramidal geometries. The reaction of a mixture of (Me3Si)2PLi and Ph2P-P(SiMe3)Li with [CpZrCl3] in toluene yields the dinuclear complex [Cp2Zr2Cl5(Ph2PPPSiMe3)(Li THF DME)]. 相似文献
42.
Rafa Espínola 《Nonlinear Analysis: Theory, Methods & Applications》2011,74(1):27-34
In this paper we study the regularity of geodesic Ptolemy spaces and apply our findings to metric fixed point theory. It is an open question whether such spaces with a continuous midpoint map are CAT(0) spaces. We prove that if a certain uniform continuity is imposed on such a midpoint map then these spaces, if complete, are reflexive (that is, the intersection of decreasing families of bounded closed and convex subsets is nonempty) and that bounded sequences have unique asymptotic centers. These properties will then be applied to yield a series of fixed point results specific to CAT(0) spaces. 相似文献
43.
Results on the existence and non-existence of nontrivial
\mathbb L1{\mathbb L^1}-solutions of the refinement equation
f(x)=òW|detK(w)|f(K(w)x-L(w))dP(w)f(x)={\int\limits_{\Omega}}|\det K(\omega)|f(K(\omega)x-L(\omega))dP(\omega) 相似文献
44.
Milena Špírková Jelena Pavli?evi? Adam Strachota Rafa? Poreba Oskar Bera Ludmila Kaprálková Josef Baldrian Miroslav Šlouf Nada Lazi? Jaroslava Budinski-Simendi? 《European Polymer Journal》2011,47(5):959-972
Novel all-aliphatic polycarbonate-based polyurethane (PC-PU) elastomers, as well as PC-PU nanocomposites filled with organic-modified clays were synthesized, characterized and studied. It was found that they have very attractive mechanical properties (e.g., elongation at break between 600% and 800%). The prepared PC-PUs possess a distinctly segmented structure, which is the key prerequisite for their behavior as strong physical rubbery networks. All synthesized materials melt at elevated temperatures (between 110 and 200 °C) and hence can be processed like normal thermoplastics. The dispersion of the clay nanofiller was achieved by its one day swelling in the alcohol and a brief successive stirring. This procedure is very successful and leads to a partial exfoliation of the clay (documented by X-ray diffraction and TEM). The best nanocomposites with very good tensile properties, particularly with significantly increased moduli were obtained using the bentonite nanofiller. The study shows that the nanofiller interacts strongly with the hard domains and influences their melting temperature (DMTA and DSC), but it does not affect the glass transition temperature of soft domains. While Cloisite 15A was found to interact preferentially with the hard domains, the organic modified bentonite shows a strong interaction with both soft and hard segments, behaving as a blending agent. Hard domains in neat matrices, formed by hydrogen bonding of hard segments, were practically invisible by X-ray or TEM, but were successfully detected by AFM. Besides excellent mechanical properties, the prepared elastomers and their nanocomposites showed an interesting phase behavior (which was studied by combining DMTA and modulated DSC). 相似文献
45.
Detection of apoptosis is one of the main criteria of preimplantation embryo growth potential assessment. Recent developments in lab-on-a-chip techniques has led to apoptosis detection and monitoring on a single cell or embryo level. However, single embryo apoptosis detection without a change in embryo developmental competence and post-examination "recovery" still remains a challenge. In this paper we present a lab-on-a-chip, co-working with miniaturized optical instrumentation, which allows supravital examination of single embryos for the presence of apoptotic blastomers with full after lab-on-a-chip study "recovery" and maintenance of their further developmental capacity. 相似文献
46.
Rafał Frański 《Journal of mass spectrometry : JMS》2004,39(3):272-276
The complexes of 2,5-disubstituted-1,3,4-oxadiazoles, namely 2,5-diphenyl-1,3,4-oxadiazole (1), 2,5-bis(2-pyridyl)-1,3,4-oxadiazole (2) and 2,5-bis(4-pyridyl)-1,3,4-oxadiazole (3), with copper cation were studied by electrospray ionization mass spectrometry (ESI-MS). The ability of the compounds studied to form complexes with copper (under the ESI conditions) can be ordered as 2 > 1 > 3. The compounds studied tend to form both 1 : 1 and 2 : 1 chelate complexes with both copper(II) and copper(I). The complexes with copper(I) are formed in the ESI process. The influence of solvent polarity, solution flow-rate, counter ions (Cl−, NO3−, CH3COO−, SO42−, acetylacetonates) on the type of the ions observed was studied. Copyright © 2004 John Wiley & Sons, Ltd. 相似文献
47.
This paper deals with a class
of pseudorandom bit generators – modified alternating
–generators. This class is constructed similarly to the class
of alternating step generators. Three subclasses of
are distinguished, namely linear, mixed and nonlinear generators. The main attention is devoted to the subclass
of linear and mixed generators generating periodic sequences with maximal period lengths. A necessary and sufficient condition for all sequences generated by the linear generators of
to be with maximal period lengths is formulated. Such sequences have good statistical properties, such as distribution of zeroes and ones, and large linear complexity. Two methods of cryptanalysis of the proposed generators are given. Finally, three new classes of modified alternating
–generators, designed especially to be more secure, are presented. 相似文献
48.
Gałezowska J Janicki R Mondry A Burgada R Bailly T Lecouvey M Kozłowski H 《Dalton transactions (Cambridge, England : 2003)》2006,(36):4384-4394
The proton and metal complex equilibria of trans-cyclohexane-1,2-diamine-N,N,N',N'-tetrakis(methylenephosphonic acid) (CDTP) with lanthanide(iii) ions, where Ln(III) = La(III), Nd(III), Sm(III), Eu(III), Gd(III), Tb(III), Ho(III) and Lu(III) were studied. The stoichiometry, protonation and complex formation constants were determined by potentiometric titration at 25.0 degrees C and ionic strength of 0.1 mol dm(-3) (KCl). All metal ions form several species: [LnH4L]-, [LnH3L](2-), [LnH2L](3-), [LnHL](4-), [LnL](5-), [LnH(-1)L](6-) and [LnH(-2)L](7-) in the pH range between 2 and 11. The stability constants log beta(LnL) were found to be between 14.7 and 16.7. The studied complexes were also characterized by spectroscopic methods (31P NMR, UV-Vis absorption and emission spectroscopy). These studies allowed to reveal a distinct structural change of the Ln(III)-CDTP complex which occurs between protonated and hydroxy species in solutions at pH around 7.5. The major change is caused by the involvement of both nitrogen donors in the metal ion coordination occurring in ML species. The data obtained from UV-Vis spectroscopy allowed to draw conclusions about complex symmetry and to estimate a number of coordinated water molecules. The hydration number or more precisely the number of two OH oscillators was found to be approximately one in all species formed over the pH range between 5 and 10. The structure of the major hydroxy complex was supported by X-ray crystallographic data. The crystal structures of the Eu(III) and Tb(III) complexes clearly show that the CDTP ligand is coordinated to the Ln(III) ion by two nitrogen and four oxygen atoms in such a way that only one oxygen atom from each phosphonic group is placed in the lanthanide inner sphere. The monomeric complex anion is connected to a symmetry related ion through short hydrogen bonds formed by two hydroxy ions and one water molecule. In this way the two neighbouring anions form a quasi-dimer in which one of the Ln(III) ion is seven-coordinate (two N atoms, four O atoms and one hydroxy ion) and the other is eight-coordinate (two N atoms, four O atoms, one hydroxy ion and one water molecule). 相似文献
49.
Frański R Klonowska-Wieszczyck K Borowiak-Resterna A Olszanowski A 《European journal of mass spectrometry (Chichester, England)》2006,12(5):311-316
The interactions of copper(II) with N-alkyl-pyridine-2-carboxamides (M) were studied by electrospray ionization mass spectrometry. The influence of solvent and counter ion (Cl-, ClO4-) on the type of ions (complexes) observed was discussed. By cone voltage increase, the fragmentation "in source" of the ions discussed was achieved. In methanol solution containing N-alkyl-pyridine-2-carboxamide (M) and CuCl2 the singly- and doubly charged-ions [M+CuCl]+ and [M2+Cu]+2 were detected. In acetonitrile solution containing N-alkyl-pyridine-2-carboxamide and CuCl2, the copper(I)-containing ions [M+CH3CN+Cu]+ were formed. The use of Cu(ClO4)2 instead of CuCl2 resulted in more abundant doubly-charged ions in both methanol and acetonitrlile solutions and, for the former solution, the ions containing methoxyl anion, namely [M+CuOCH3]+, were observed. When water was used as a solvent, the abundant ions corresponding to the protonated ligands were formed, while the ions corresponding to copper complexes were characterised by low abundances. 相似文献
50.
Frański R 《European journal of mass spectrometry (Chichester, England)》2006,12(3):199-204
The effect of solvent and counter ion on the complexes of 2,5-bis(2-pyridyl)-1,3,4-oxadiazole (1) with Fe+2 and Fe+3 has been studied by electrospray ionization mass spectrometry (ESI/MS). As expected, upon ESI conditions the metal reduction proceeds, but it can be deduced that complexes with Fe+2 are favored over those with Fe+3. When methanol is used as solvent, the formation of complexes of stoichiometry 2:1 and 1:1 with counter ion attached (monovalent anion) is favored, for example, [1(2)+FeCl]+ ion. The use of methanol/water (1/1) as solvent favors the formation of complexes of stoichiometry 2:1 and 3:1, namely doubly charged [1(2)+Fe]+2 and [1(3)+Fe]+2 ions. The complexes containing anion of oxidative properties (ClO4-, NO3-), when the higher cone voltage is applied, yield unusual species [1n+FeOm]+ (n=1, 2; m=1, 2). The use of divalent counter ion (SO4(-2)) resulted in formation of complexes containing two iron cations, namely [1n+Fe2SO4]+2 (n=2, 3, 4) ions. These ions can be regarded as Fe-1 complexes bridged by a sulfate anion. 相似文献
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