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311.
Kristensen EM Nederberg F Rensmo H Bowden T Hilborn J Siegbahn H 《Langmuir : the ACS journal of surfaces and colloids》2006,22(23):9651-9657
The structure of a biomimetic phosphorylcholine (PC)-functionalized poly(trimethylene carbonate) (PC-PTMC-PC), linked to a silicon substrate through an aminolysis reaction at 120 degrees C with (3-aminopropyl)trimethoxysilane (APTMS), was studied using photoelectron spectroscopy. Two chemical states were found for the unreacted APTMS amine, a neutral state and a protonated state, where the protonated amine on average was situated closer to the silicon substrate than the neutral amine. The experiments also indicated the presence of a third chemical state, where amines interact with unreacted silanol groups. The PTMC chains of the grafted films were found to consist of only 2-3 repeat units, with the grafted chains enriched in the zwitterionic end group, suggesting that these groups are attracted to the surface. This was further supported by the experiments showing that the PC groups were situated deeper within the film. 相似文献
312.
A simple and sensitive method for determination of phosphoric acid triesters at trace levels in human plasma sample is described. In this work, solid-phase microextraction (SPME) is employed as a sample preparation procedure for extraction and pre-concentration of alkyl and aryl phosphates followed by gas chromatography coupled to inductively coupled plasma mass spectrometry (GC-ICP-MS) for phosphorus-specific and very sensitive determination of these compounds in human plasma. The detection limits from blood plasma were 50 ngL(-1) (tripropyl phosphate), 17 ngL(-1) (tributyl phosphate), 240 ngL(-1) (tris(2-chloroethyl) phosphate) and 24 ngL(-1) (triphenyl phosphate). Sample preparation involves plasma deproteinization followed by direct immersion SPME with 65 microm poly(dimethylsiloxane/divinylbenzene) fiber. Extraction was performed at 40 degrees C for 30 min and at pH 7.0 in 10 mM sodium carbonate buffer. The reported method, to our knowledge, describes the first application of SPME with element-specific detection for analysis of phosphoric acid esters. Application of the method to the plasma samples, previously stored in poly(vinyl chloride) plasma bags revealed the presence of triphenyl phosphate, which was further confirmed by SPME GC time-of-flight high-resolution mass spectrometry. 相似文献
313.
B.H. Jørgensen J.N. Sørensen M. Brøns 《Theoretical and Computational Fluid Dynamics》2003,16(4):299-317
By applying Proper Orthogonal Decomposition (POD) one is
able to extract a limited amount of data which characterizes a flow of
interest. The modes resulting from the decomposition form a basis in
the phase space on which a Galerkin projection of the equations of
motion can be performed. By carrying out such a procedure one obtains
a low-dimensional model consisting of a reduced set of Ordinary
Differential Equations (ODEs) which models the original equations.
A technique called Sequential Proper Orthogonal Decomposition (SPOD)
is developed to perform decompositions suitable for low-dimensional
models. SPOD is capable of transforming data organized in
different sets separately while still producing orthogonal modes.
A low-dimensional model is constructed and used for analyzing
bifurcations occurring in the flow in the lid-driven cavity with
a rotating rod. The model allows one of the free parameters to appear in
the inhomogeneous boundary conditions without the addition of any
constraints. This is necessary because both the driving lid and the
rotating rod are controlled simultaneously. Apparently, the results
reported for this model are the first to be obtained for
a low-dimensional model based on projections on POD modes for more than
one free parameter.
Received 29 October 2001 and accepted 27 August 2002 Published online 13 January 2003
Communicated by P. Hall 相似文献
314.
315.
Ramona Abele Liga Zvejniece Edgars Abele Kira Rubina Pavel Arsenyan Marina Vandish Olga Pudova Maija Dambrova Ilona Domracheva Irina Shestakova Juris Popelis Edmunds Lukevics 《应用有机金属化学》2004,18(4):181-186
New silicon derivatives of hetaryl propargyl sulfides and propargyl alcohols were synthesized using phase‐transfer catalytic and organometallic methods. These compounds were tested for acute toxicity and neurotropic activity in the pentylenetetrazole test, and for phenamine hypothermia, phenamine hyperactivity and passive avoidance response tests. We have found that the silyl propargyl alcohols and sulfides are low toxicity compounds, the LD50 being 700–1300 mg kg?1. In the PAR test, the synthesized compounds exerted some memory‐improving activity. For di‐1‐(3‐methyl‐3‐hydroxybutyn‐1‐yl)methyl(3‐iodopropyl)silane ( 16 ) the effect was statistically significant and amounted to 250% of the control level. In the pentylenetetrazole test, all compounds possessed anticonvulsant activity, the most active compounds being 3‐(benzoxazolylthio)‐1‐propynyl(trimethyl)silane ( 6 ) and di‐[2‐(1‐hydroxycyclohexyl)ethynyl]methyl(3‐iodopropyl)silane ( 17 ). The phenamine‐induced hyperactivity was significantly elevated after treatment with (3‐trimethylsilyl‐2‐propynyl)thiobenzene ( 1 ) or di‐[1‐(3‐methyl‐3‐hydroxybutyn‐1‐yl)diphenylsilane ( 12 ). Our data show that these silicon derivatives of hetaryl propargyl sulfides and propargyl alcohols possess certain memory improving and anticonvulsant activity that should be studied in detail to evaluate the receptor systems involved. Copyright © 2004 John Wiley & Sons, Ltd. 相似文献
316.
Edgars bele Kira Rubina Mendel Fleisher Juris Popelis Pavel Arsenyan Edmunds Lukevics 《应用有机金属化学》2002,16(3):141-147
The Stille reaction of unsymmetric diynes from terminal bromoalkynes with alkynylstannane in the presence of palladium catalyst and cesium fluoride was studied. The system (bromoalkyne: PhC≡CSnMe3:Pd2(dba)3:PPh3:CsF:18‐crown‐6) = (1:1:0.015:0.06:2.2:0.1) in toluene at reflux temperature was found to be the most favored. Products were obtained in 31–100% yields. Correlations between calculated electron density, dipole moments and 13C NMR spectral data of synthesized bromoacetylenes and diynes have been carried out. Copyright © 2002 John Wiley & Sons, Ltd. 相似文献
317.
Juris Meija Zoltan Mester Alessandro D’Ulivo 《Journal of the American Society for Mass Spectrometry》2007,18(2):337-345
Mass spectra of fully and partially deuterated As, Sb, Bi, Ge, and Sn hydrides have been obtained using several mathematical
approaches aimed at signal extraction and reconstruction. Study of such hydride mixtures is important for the elucidation
of hydride generation mechanisms. In this approach, mass spectra of partially deuterated isotopomers, i.e., AsH2D and AsHD2, are extracted using the weighted two-band target entropy minimization method. Alternatively, these mass spectra were constructed
from the mass spectra of fully deuterated and hydrogenated hydrides using the statistical approach in fragmentation pathways.
Concentration profiles of all deuterated hydrides were obtained from their overlapping mixture mass spectra using least-squares
deconvolution. 相似文献
318.
Cu-ATSM: a radiopharmaceutical for the PET imaging of hypoxia 总被引:3,自引:0,他引:3
Copper(II)-diacetyl-bis(N(4)-methylthiosemicarbazone), Cu-ATSM, labeled with a positron emitting isotope of copper ((60)Cu, (61)Cu, (62)Cu or (64)Cu) has been shown, in vitro and in vivo, to be selective for hypoxic tissue. In silico studies have explored the mechanism of its hypoxia selectivity, and clinical studies with this agent have shown non-invasive imaging data that is predictive of a cancer patients' response to conventional therapy. This Perspective discusses the evolution of Cu-ATSM, how its selectivity can be improved upon, and where this metal-ligand platform could be taken in the future. 相似文献
319.
Måns Andréasson Dr. Naresh Bhuma Dr. Nils Pemberton Dr. Erik Chorell 《Chemistry (Weinheim an der Bergstrasse, Germany)》2022,28(65):e202202020
This study aims to deepen the knowledge of the current state of rational G4-ligand design through the design and synthesis of a novel set of compounds based on indoles, quinolines, and benzofurans and their comparisons with well-known G4-ligands. This resulted in novel synthetic methods and G4-ligands that bind and stabilize G4 DNA with high selectivity. Furthermore, the study corroborates previous studies on the design of G4-ligands and adds deeper explanations to why a) macrocycles offer advantages in terms of G4-binding and -selectivity, b) molecular pre-organization is of key importance in the development of strong novel binders, c) an electron-deficient aromatic core is essential to engage in strong arene-arene interactions with the G4-surface, and d) aliphatic amines can strengthen interactions indirectly through changing the arene electrostatic nature of the compound. Finally, fundamental physicochemical properties of selected G4-binders are evaluated, underscoring the complexity of aligning the properties required for efficient G4 binding and stabilization with feasible pharmacokinetic properties. 相似文献
320.
Juris Meija 《Analytical and bioanalytical chemistry》2010,396(1):185-186