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101.
Electric field modulation in tissue electroporation with electrolytic and non-electrolytic additives
Electroporation, cell membrane permeabilization with short electrical field pulses, is used in tissue for in vivo gene therapy, drug therapy and minimally invasive tissue ablation. For the electroporation to be successful, the electrical field that develops during the application of the pulses needs to be precisely controlled. In this study we investigate the use of electrolytic and non-electrolytic gels to generate the precise electrical fields required for controlled electroporation, in heterogeneous and irregular tissues, in vivo. Finite element computer simulations are used to illustrate various applications, such as the treatment of irregularly shaped organs and interior cavities. The feasibility of the concept is demonstrated experimentally in vivo with a rat liver subjected to irreversible electroporation. 相似文献
102.
An automatic system based on multisyringe flow injection analysis (MSFIA) and lab-on-valve (LOV) flow techniques for separation and pre-concentration of 226Ra from drinking and natural water samples has been developed. The analytical protocol combines two different procedures: the Ra adsorption on MnO2 and the BaSO4 co-precipitation, achieving more selectivity especially in water samples with low radium levels. 相似文献
103.
Consumption of non-steroidal anti-inflammatory drugs (NSAIDs) is increasing and with it the danger of environmental pollution
by pharmaceutical residues. Publications regarding NSAIDs in the environment not only show that they are toxic to many animal
species, but also highlight the need for robust analytical methods for monitoring the level of such contaminants in environmental
matrices. In our study we selected the four most widely used NSAIDs in Slovenia and Central Europe, ibuprofen, naproxen, ketoprofen
and diclofenac, and studied their extraction from sediment samples. We examined several extraction techniques (ultrasonic
extraction, Soxhlet extraction, pressurized liquid extraction, supercritical fluid extraction and microwave-assisted extraction)
using a spiked sediment sample and determined optimal extraction conditions. After extraction we applied a clean-up step,
derivatisation of the analytes and gas chromatography with mass spectrometric detection (GC-MSD) and selected the most appropriate
extraction procedure. The optimised analytical method chosen for analysis of sediment samples consisted of microwave-assisted
extraction, clean-up of the extract with SPE, derivatisation with MSTFA and determination with GC-MSD. The optimised procedure
was applied to the analysis of two environmental river samples taken from the vicinity of Novo mesto, the biggest town in
the south eastern part of Slovenia with 62,000 inhabitants, a hospital and a pharmaceutical factory in its vicinity. While
analysis of the sample taken upstream of the town showed no detectable amounts of NSAIDs, analysis of samples taken downstream
showed quantifiable levels of two of the studied NSAIDs (naproxen and ketoprofen). Besides these two NSAIDs, river water samples
sampled at the same time and location on the River Krka also showed the presence of diclofenac. Sampling on the River Krka
and other Slovene rivers will in the future be repeated at different sampling points in order to track down the main sources
of pollution. 相似文献
104.
Leszek Wachowski Antoni Grodzicki Piotr Piszczek Monika Richert Magdalena Hofman 《Reaction Kinetics and Catalysis Letters》2007,91(1):93-99
Hydrogenation of styrene has been applied as a test reaction to study the catalytic activity of TiO2 deposited by the CVD (chemical vapour deposition) method on the surface of a carbonaceous material enriched in nitrogen (CN). 相似文献
105.
Isidoro Lpez Mehmed Z. Ertem Somnath Maji Jordi Benet‐Buchholz Anke Keidel Uwe Kuhlmann Peter Hildebrandt Christopher J. Cramer Victor S. Batista Antoni Llobet 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2014,126(1):209-213
The homogeneous catalysis of water oxidation by transition‐metal complexes has experienced spectacular development over the last five years. Practical energy‐conversion schemes, however, require robust catalysts with large turnover frequencies. Herein we introduce a new oxidatively rugged and powerful dinuclear water‐oxidation catalyst that is generated by self‐assembly from a mononuclear catalyst during the catalytic process. Our kinetic and DFT computational analysis shows that two interconnected catalytic cycles coexist while the mononuclear system is slowly and irreversibly converted into the more stable dinuclear system: an extremely robust water‐oxidation catalyst that does not decompose over extended periods of time. 相似文献
106.
Masllorens E Rodríguez M Romero I Roglans A Parella T Benet-Buchholz J Poyatos M Llobet A 《Journal of the American Chemical Society》2006,128(16):5306-5307
Three new Ru-aqua complexes containing a mixed carbene and pyridylic ligands with general formulas [Ru(CNC)(bpy)(H2O)](PF6)2 (1) (CNC is 2,6-bis(butylimidazol-2-ylidene)pyridine; bpy is 2,2'-bipyridine) and cis-/trans-[Ru(CNC)(nBu-CN)(H2O)](PF6)2 (cis-2 and trans-2) (nBu-CN is 2-(butylimidazol-2-ylidene)pyridine) have been prepared and structurally characterized both in the solid state (monocrystal X-ray diffraction analysis for 1 and for the related complex trans-[Ru(Br)(CNC)(nBu-CN)](PF6)) and in solution (for all of them) through NMR. The electrochemical properties of these three Ru-aqua complexes have been investigated by cyclic voltammetry, differential pulse voltammetry and Coulombimetric techniques. It is found that, for complex 1 at pH 7, the difference between the IV/III and the III/II redox couples (DeltaE1/2) is 50 mV, which is the smallest ever reported for this type of complex. On the other hand, for complexes cis-2 and trans-2, the oxidation state III is unstable with respect to disproportionation to II and IV. The reactivity of their Ru=O species has been tested toward cis-beta-methylstyrene oxidation, and it has been compared to [Ru(O)(trpy)(bpy)]2+. An inverse correlation between the degree of cis/trans-epoxide isomerization and DeltaE1/2 is found. In particular, for complexes cis-2 and trans-2, which have a DeltaE1/2 < 0, the epoxidation is highly stereoselective, yielding only cis-epoxide. 相似文献
107.
Ballester P Costa A Castilla AM Deyà PM Frontera A Gomila RM Hunter CA 《Chemistry (Weinheim an der Bergstrasse, Germany)》2005,11(7):2196-2206
Three isomeric zinc bisporphyrins have been prepared by covalently linking together two aminoporphyrins with an isophthalic acid derivative. The porphyrins differ in the substitution pattern on the meso phenyl groups, that is, ortho, meta, or para. Titrations carried out by UV-visible and 1H NMR spectroscopy have been used to map out the stabilities and the stoichiometries of the complexes formed with 1,4-diazabicyclo[2.2.2]octane (DABCO) in chloroform. The ortho- and meta-substituted bisporphyrins form 1:1 intramolecular sandwich complexes. The para-substituted bisporphyrin cannot adopt the cofacial conformation required for this type of complex and forms a higher order 2:2 intermolecular assembly, which is stable over a wide range of DABCO concentrations. 相似文献
108.
Artur Sikorski Karol Krzymiski Antoni Konitz Jerzy Baejowski 《Acta Crystallographica. Section C, Structural Chemistry》2005,61(4):o227-o230
The title compounds, C21H14Cl2NO2+·CF3O3S−, (I), and C20H11Cl2NO2, (II), form triclinic crystals. Adjacent cations of (I) are oriented either parallel or antiparallel; in the latter case, they are related by a centre of symmetry. Together with the CF3SO3− anions, the antiparallel‐oriented cations of (I) form layers in which the molecules are linked via a network of C—H·O and π–π interactions (between the benzene rings). These layers, in turn, are linked via a network of multidirectional π–π interactions between the acridine rings, and the whole lattice is stabilized by electrostatic interactions between ions. Adjacent molecules of (II) are oriented either parallel or antiparallel; in the latter case, they are related by a centre of symmetry. Parallel‐oriented molecules are arranged in chains stabilized via C—H·Cl interactions. These chains are oriented either parallel or antiparallel and are stabilized, in the latter case, via multidirectional π–π interactions and more generally via dispersive interactions. Acridine and independent benzene moieties lie parallel in the lattices of (I) and (II), and are mutually oriented at an angle of 33.4 (2)° in (I) and 9.3 (2)° in (II). 相似文献
109.
[reaction: see text] The Pauson-Khand reaction is notably accelerated by TEMPO. According to DFT calculations, TEMPO could trigger a radical, low-energy pathway for the reaction by facilitating the decarbonylation of doublet complexes arising either from a CO/nitroxide exchange or from nitroxide addition to a CO ligand. 相似文献
110.
I. Colon G. T. Kwiatkowski 《Journal of polymer science. Part A, Polymer chemistry》1990,28(2):367-383
This paper describes a totally new method for the formation of high molecular weight aromatic polymers. High molecular weight polyarylethersulfones are produced by nickel catalyzed coupling of aryl dichloride monomers. Metallic zinc is used to drive the polymerization reaction which takes place under relatively mild conditions in the presence of triphenylphosphine and a dipolar aprotic solvent. The versatility of the reaction is demonstrated, as well as the ability to provide a variety of high temperature polymers from readily available and inexpensive monomers. It is possible to use an integrated two-step process to produce aryl dichlorides from inexpensive aryl chlorides, and then to couple these directly to polymer without need for isolation and purification. This process resulted from a fundamental understanding of the chemistry and the use of statistically designed experiments to identify the important reaction parameters and to optimize the degree of polymerization. 相似文献