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排序方式: 共有491条查询结果,搜索用时 15 毫秒
71.
Ulrik Franzen Lene Jorgensen Claus Larsen Niels H. H. Heegaard Jesper Østergaard 《Electrophoresis》2009,30(15):2711-2719
The potential of using CE frontal analysis (CE‐FA) to study the interactions between a range of charged low molecular weight drug substances and liposomes was evaluated. The liposomes used were net negatively charged and consisted of 2‐oleoyl‐1‐palmitoyl‐sn‐glycero‐3‐phosphocholine and 1,2‐dipalmitoyl‐sn‐glycero‐3‐phosphate monosodium salt in a ratio of 80/20 mol%. Apparent distribution coefficients (Dmem), defined as the molar concentration of drug substance in the membrane phase divided by the molar concentration of drug substance in the aqueous phase, were successfully determined for six positively and eight negatively charged drug substances with log Dmem ranging from 1.35 to 3.63. The extent of liposome–buffer distribution was found to be dependent on the drug concentration. The results obtained with the developed CE‐FA method were in good agreement with results obtained by equilibrium dialysis. Furthermore, the CE‐FA method was faster, less labor intensive and required smaller sample volumes (~50 μL) compared with equilibrium dialysis. Thus, CE‐FA is an efficient and useful tool for the characterization of interactions between liposomes and low molecular weight drug substances. 相似文献
72.
The synthesis of substituted 2-cyanoarylboronic esters is described via lithiation/in situ trapping of the corresponding methoxy-, trifluoromethyl-, fluoro-, chloro-, and bromobenzonitriles. The crude arylboronic esters were obtained in high yields and purities and with good regioselectivities. 相似文献
73.
We consider an index-guiding silica photonic crystal fiber with a triangular hole pattern and a periodically poled quadratic nonlinearity. By tuning the pitch and the relative hole size, second-harmonic generation with zero group-velocity mismatch is found for any fundamental wavelength above 780 nm. The nonlinear strength is optimized when the fundamental has maximum confinement in the core. The conversion bandwidth allows for femtosecond-pulse conversion, and 4%-180%W(-1)cm(-2) relative efficiencies were found. 相似文献
74.
Rocío García-Vzquez Umberto M. Battisti Jesper T. Jrgensen Vladimir Shalgunov Lars Hvass Daniel L. Stares Ida N. Petersen Franois Crestey Andreas Lffler Dennis Svatunek Jesper L. Kristensen Hannes Mikula Andreas Kjaer Matthias M. Herth 《Chemical science》2021,12(35):11668
Pretargeted imaging can be used to visualize and quantify slow-accumulating targeting vectors with short-lived radionuclides such as fluorine-18 – the most popular clinically applied Positron Emission Tomography (PET) radionuclide. Pretargeting results in higher target-to-background ratios compared to conventional imaging approaches using long-lived radionuclides. Currently, the tetrazine ligation is the most popular bioorthogonal reaction for pretargeted imaging, but a direct 18F-labeling strategy for highly reactive tetrazines, which would be highly beneficial if not essential for clinical translation, has thus far not been reported. In this work, a simple, scalable and reliable direct 18F-labeling procedure has been developed. We initially studied the applicability of different leaving groups and labeling methods to develop this procedure. The copper-mediated 18F-labeling exploiting stannane precursors showed the most promising results. This approach was then successfully applied to a set of tetrazines, including highly reactive H-tetrazines, suitable for pretargeted PET imaging. The labeling succeeded in radiochemical yields (RCYs) of up to approx. 25%. The new procedure was then applied to develop a pretargeting tetrazine-based imaging agent. The tracer was synthesized in a satisfactory RCY of ca. 10%, with a molar activity of 134 ± 22 GBq μmol−1 and a radiochemical purity of >99%. Further evaluation showed that the tracer displayed favorable characteristics (target-to-background ratios and clearance) that may qualify it for future clinical translation.A simple, scalable and reliable direct 18F-labeling procedure has been developed and applied to obtain a pretargeting tetrazine-based imaging agent with favorable in vivo characteristics. 相似文献
75.
Summary: Water exchange between five polyacrylamide gels (Bulkamid®, Aquamid®, Rectamid®, HV-PAAG, Acuvue) with a physiological salt solution was determined by means of tritium-labeled water. Urea and chloride exchange was also determined in Acuvue. The method was a modified version to measure rapid transport processes in red blood cells. The study shows that water and solutes easily exchange between the hydrogel under study and the surrounding medium, independent of the solid polymer content (2.5–40 wt%) and an over ten-fold variation of the cross-linking density. 相似文献
76.
Balmes O Resta A Wermeille D Felici R Messing ME Deppert K Liu Z Grass ME Bluhm H van Rijn R Frenken JW Westerström R Blomberg S Gustafson J Andersen JN Lundgren E 《Physical chemistry chemical physics : PCCP》2012,14(14):4796-4801
The structure and chemical composition of Pd nanoparticles exposed to pure CO and mixtures of CO and O(2) at elevated temperatures have been studied in situ by a combination of X-ray Diffraction and X-ray Photoelectron Spectroscopy in pressures ranging from ultra high vacuum to 10 mbar and from room temperature to a few hundred degrees celsius. Our investigation shows that under CO exposure, above a certain temperature, carbon dissolves into the Pd particles forming a carbide phase. Upon exposure to CO and O(2) mixtures, the carbide phase forms and disappears reversibly, switching at the stoichiometric ratio for CO oxidation. This finding opens new scenarios for the understanding of catalytic oxidation of C-based molecules. 相似文献
77.
CA Thuesen KS Pedersen M Schau-Magnussen M Evangelisti J Vibenholt S Piligkos H Weihe J Bendix 《Dalton transactions (Cambridge, England : 2003)》2012,41(37):11284-11292
The trifluorido complex mer-[CrF(3)(py)(3)] (py = pyridine) reacts with 1 equiv. of [Ln(hfac)(3)(H(2)O)(2)] and depending on the solvent forms the tetranuclear clusters [Cr(2)Ln(2)(μ-F)(4)(μ-OH)(2)(py)(4)(hfac)(6)], 1Ln, and [Cr(2)Ln(2)(μ-F)(4)F(2)(py)(6)(hfac)(6)], 2Ln, in acetonitrile and 1,2-dichloroethane, respectively (Ln = Y, Gd, Tb, Dy, Ho, and Er; hfacH = 1,1,1,5,5,5-hexafluoroacetylacetone). Reaction with [Dy(hfac)(3)(H(2)O)(2)] in dichloromethane produces the dinuclear cluster [CrDy(μ-F)F(OH(2))(py)(3)(hfac)(4)], 3Dy. All the clusters feature fluoride bridges between the chromium(iii) and lanthanide(iii) centres. Fits of susceptibility data for 1Gd and 2Gd reveal the fluoride-mediated chromium(iii)-lanthanide(iii) exchange interactions to be 0.43(5) cm(-1) and 0.57(7) cm(-1), respectively (in the convention). Heat capacity measurements on 2Gd reveal a moderate magneto-caloric effect (MCE) reaching -ΔS(m)(T) = 11.4 J kg(-1) K(-1) for ΔB(0) = 9 T → 0 T at T = 4.1 K. Out-of-phase alternating-current susceptibility (χ') signals are observed for 1Dy, 2Dy and 2Tb, demonstrating slow relaxation of the magnetization. 相似文献
78.
Grgić J Ott JR Wang F Sigmund O Jauho AP Mørk J Mortensen NA 《Physical review letters》2012,108(18):183903
A common strategy to compensate for losses in optical nanostructures is to add gain material in the system. By exploiting slow-light effects it is expected that the gain may be enhanced beyond its bulk value. Here we show that this route cannot be followed uncritically: inclusion of gain inevitably modifies the underlying dispersion law, and thereby may degrade the slow-light properties underlying the device operation and the anticipated gain enhancement itself. This degradation is generic; we demonstrate it for three different systems of current interest (coupled-resonator optical waveguides, Bragg stacks, and photonic crystal waveguides). Nevertheless, a small amount of added gain may be beneficial. 相似文献
79.
Matias Sevel Rasmussen Tor Justesen Anders Dohn Jesper Larsen 《European Journal of Operational Research》2012
In the Home Care Crew Scheduling Problem a staff of home carers has to be assigned a number of visits to patients’ homes, such that the overall service level is maximised. The problem is a generalisation of the vehicle routing problem with time windows. Required travel time between visits and time windows of the visits must be respected. The challenge when assigning visits to home carers lies in the existence of soft preference constraints and in temporal dependencies between the start times of visits. 相似文献
80.
Manson JL Baldwin AG Scott BL Bendix J Del Sesto RE Goddard PA Kohama Y Tran HE Ghannadzadeh S Singleton J Lancaster T Möller JS Blundell SJ Pratt FL Zapf VS Kang J Lee C Whangbo MH Baines C 《Inorganic chemistry》2012,51(14):7520-7528
[Ni(HF(2))(3-Clpy)(4)]BF(4) (py = pyridine) is a simple one-dimensional (1D) coordination polymer composed of compressed NiN(4)F(2) octahedra that form chains with bridging HF(2)(-) ligands. In spite of significant distortion of the HF(2)(-) bridge, a quasi-1D antiferromagnetic (AFM) behavior was observed with J(FHF) = 4.86 K. 相似文献