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51.
52.
Floyd WC Klemm PJ Smiles DE Kohlgruber AC Pierre VC Mynar JL Fréchet JM Raymond KN 《Journal of the American Chemical Society》2011,133(8):2390-2393
One essential requirement for more sensitive gadolinium-based MRI contrast agents is to slow the molecular tumbling of the gadolinium(III) ion, which increases the gadolinium's relaxivity (i.e., its ability to speed up the NMR relaxation of nearby water molecules). One route to this is through conjugation to high-molecular-weight polymers such as dendrimers. In this work, amine-functionalized TREN-bis(1,2-HOPO)-TAM-ethylamine and TREN-bis(1-Me-3,2-HOPO)-TAM-ethylamine ligands have been synthesized and attached to biocompatible 40 kDa esteramide (EA)- and poly-l-lysine (PLL)-based dendrimers capable of binding up to eight gadolinium complexes. These conjugates have T(1) relaxivities of up to 38.14 ± 0.02 mM(-1) s(-1) per gadolinium at 37 °C, corresponding to relaxivities of up to 228 mM(-1) s(-1) per dendrimer molecule. This relaxivity expressed on a "per Gd" basis is several times that of the small-molecule complexes and an order of magnitude higher than that of current commercial agents. Because of their high performance and low toxicity, these macromolecules may constitute an attractive complement to currently available gadolinium(III)-based contrast agents. 相似文献
53.
A European interlaboratory collaborative study was conducted to validate a method for the quantitative determination of lipophilic
marine biotoxins based on high-performance liquid chromatography–tandem mass spectrometry. During this study, the diarrhetic
shellfish poisoning toxins okadaic acid, dinophysis toxin1 and 2 including their esters, the azaspiracids 1-3, pectenotoxin2,
and the yessotoxins were investigated at concentration levels near the limit of quantification and near the legal limit. Naturally
contaminated blue mussels, both raw and cooked and spiked extracts of clams and oysters were studied and results were obtained
for 16 test samples from 16 laboratories representing eight different countries. This article summarizes the study outcome
concerning validation key parameters like specificity, linearity, limit of detection, accuracy/recovery, and precision. Further,
influences of cooking of mussels before homogenization or hydrolysis on method robustness have been evaluated. 相似文献
54.
Padmanaban M Müller P Lieder C Gedrich K Grünker R Bon V Senkovska I Baumgärtner S Opelt S Paasch S Brunner E Glorius F Klemm E Kaskel S 《Chemical communications (Cambridge, England)》2011,47(44):12089-12091
A modular approach for the synthesis of highly ordered porous and chiral auxiliary (Evans auxiliary) decorated metal-organic frameworks is developed. Our synthesis strategy, which uses known porous structures as model materials for incorporation of chirality via linker modification, can provide access to a wide range of porous materials suitable for enantioselective separation and catalysis. Chiral analogues of UMCM-1 have been synthesized and investigated for the enantioseparation of chiral compounds in the liquid phase and first promising results are reported. 相似文献
55.
Nanocelluloses: a new family of nature-based materials 总被引:2,自引:0,他引:2
Klemm D Kramer F Moritz S Lindström T Ankerfors M Gray D Dorris A 《Angewandte Chemie (International ed. in English)》2011,50(24):5438-5466
Cellulose fibrils with widths in the nanometer range are nature-based materials with unique and potentially useful features. Most importantly, these novel nanocelluloses open up the strongly expanding fields of sustainable materials and nanocomposites, as well as medical and life-science devices, to the natural polymer cellulose. The nanodimensions of the structural elements result in a high surface area and hence the powerful interaction of these celluloses with surrounding species, such as water, organic and polymeric compounds, nanoparticles, and living cells. This Review assembles the current knowledge on the isolation of microfibrillated cellulose from wood and its application in nanocomposites; the preparation of nanocrystalline cellulose and its use as a reinforcing agent; and the biofabrication of bacterial nanocellulose, as well as its evaluation as a biomaterial for medical implants. 相似文献
56.
Fragoso A Latta D Laboria N von Germar F Hansen-Hagge TE Kemmner W Gärtner C Klemm R Drese KS O'Sullivan CK 《Lab on a chip》2011,11(4):625-631
A microsystem integrating electrochemical detection for the simultaneous detection of protein markers of breast cancer is reported. The microfluidic platform was realized by high precision milling of polycarbonate sheets and features two well distinguishable sections: a detection zone incorporating the electrode arrays and the fluid storage part. The detection area is divided into separate microfluidic chambers addressing selected electrodes for the measurement of samples and calibrators. The fluidic storage part of the platform consists of five reservoirs to store the reagents and sample, which are interfaced by septa. These reservoirs have the appropriate volume to run a single assay per cartridge and are manually filled. The liquids from the reservoirs are actuated by applying a positive air pressure (i.e.via a programmable syringe pump) through the septa and are driven to the detection zone via two turning valves. The application of the realised platform in the individual and simultaneous electrochemical detection of proteic cancer markers with very low detection limits are demonstrated. The microsystem has also been validated using real patient serum samples and excellent correlation with ELISA results obtained. 相似文献
57.
Mirror Symmetry, Picard-Fuchs equations and instanton corrected Yukawa couplings are discussed within the framework of toric geometry. It allows to establish mirror symmetry of Calabi-Yau spaces for which the mirror manifold had been unavailable in previous constructions. Mirror maps and Yukawa couplings are explicitly given for several examples with two and three moduli.On leave of absence from Dept. of Math., Toyama Univ., Toyama 930, Japan (address after Sept. 1, 1993)Address after Oct. 1, 1993: Dept. of Math., Harvard Univ., Cambridge, MA 02138, USA. after April 1, 1994: CERN, Theory Division, CH-1211 Geneva 23, Switzerland 相似文献
58.
Stephan Pritz Yvonne Wolf Clementine Klemm Michael Bienert 《Tetrahedron letters》2006,47(33):5893-5896
The phosphonium-type coupling reagent PyBOP, when applied to the synthesis of peptide nucleic acid (PNA) oligomers, was found to form O4-phosphonium compounds of the nucleobase guanine which can be converted into C4-modified guanine-derived PNAs by nucleophiles. 相似文献
59.
The relative efficiencies for two dissociative channels in the vacuum UV photolysis of carbonyl sulphide have been determined using the flash photolysis-resonance fluorescence technique to measure initial yields of atomic oxygen and atomic sulphur. At wavelengths above 105 nm, the dissociation of OCS to form atomic sulphur exceeded that for the formation of atomic oxygen to such an extent that only an upper limit could be placed on the minor process, ΦS >/ 50 ΦO. In addition, the flash photo-excitation of carbonyl sulphide produced a long-lived spontaneous emission in the UV and vacuum UV that might be due to molecular fluorescence from OCS. 相似文献
60.
Abstract— Dose-response curves were measured for the delay phase shift of pupae emergence of Drosophila pseudoobscura. From these curves an action spectrum was determined for this process; it suggests a flavin to be the photoreceptor pigment. 相似文献