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141.
A three-dimensional balanced steady-state free precession (b-SSFP)-Dixon technique with a novel group-encoded k-space segmentation scheme called GUINNESS (Group-encoded Ungated Inversion Nulling for Non-contrast Enhancement in the Steady State) was developed. GUINNESS was evaluated for breath-held non-contrast-enhanced MR angiography of the renal arteries on 18 subjects (6 healthy volunteers, 12 patients) at 3.0 T. The method provided high signal-to-noise and contrast renal angiograms with homogeneous fat and background suppression in short breath-holds on the order of 20 s with high spatial resolution and coverage. GUINNESS has potential as a short breath-hold alternative to conventional respiratory-gated methods, which are often suboptimal in pediatric subjects and patients with significant diaphragmatic drift/sleep apnea. 相似文献
142.
Zhong Longchun Zhang Yongsheng Wang Tao Ji Yong Norris Pauline Pan Wei-Ping 《Journal of Thermal Analysis and Calorimetry》2019,136(5):1989-1999
Journal of Thermal Analysis and Calorimetry - This work evaluated three activation methods, physical activation, chemical activation and combined physical–chemical activation, for preparing... 相似文献
143.
Justin Lange Balkis Eddhif Mehrad Tarighi Tha Garandeau Elodie Praudeau Jonathan Clarhaut Brigitte Renoux Sbastien Papot Pauline Poinot 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2019,131(49):17727-17730
The development of efficient protocols for cancer diagnosis remains highly challenging. An emerging approach relies on the detection in exhaled breath of volatile organic compounds (VOC) produced by tumours. In this context, described here is a novel strategy in which a VOC‐based probe is converted selectively in malignant tissues, by a tumour‐associated enzyme, for releasing the corresponding VOC. The latter is then detected in the exhaled breath as a tumour marker for cancer diagnosis. This approach allows the detection of several different tumours in mice, the monitoring of tumour growth and tumour response to chemotherapy. Thus, the concept of “induced volatolomics” provides a new way to explore biological processes using VOC‐based probes that could be adapted to many biomedical applications. 相似文献
144.
Jennifer Rodon Fores Miryam Criado‐Gonzalez Alain Chaumont Alain Carvalho Christian Blanck Marc Schmutz Christophe A. Serra F. Boulmedais Pierre Schaaf Loïc Jierry 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2019,131(52):18993-18998
Inspired by biology, one current goal in supramolecular chemistry is to control the emergence of new functionalities arising from the self‐assembly of molecules. In particular, some peptides can self‐assemble and generate exceptionally catalytically active fibrous networks able to underpin hydrogels. Unfortunately, the mechanical fragility of these materials is incompatible with process developments, relaying this exciting field to academic curiosity. Here, we show that this drawback can be circumvented by enzyme‐assisted self‐assembly of peptides initiated at the walls of a supporting porous material. We applied this strategy to grow an esterase‐like catalytically active supramolecular hydrogel (CASH) in an open‐cell polymer foam, filling the whole interior space. Our supported CASH material is highly efficient towards inactivated esters and enables the kinetic resolution of racemates. This hybrid material is robust enough to be used in continuous flow reactors, and is reusable and stable over months. 相似文献
145.
Daniel Colombani Philippe Chaumont 《Journal of polymer science. Part A, Polymer chemistry》1994,32(14):2687-2697
A new chain transfer agent, ethyl 2-[1-(1-n-butoxyethylperoxy) ethyl] propenoate (EBEPEP) was used in the free radical polymerization of methyl methacrylate (MMA), styrene (St), and butyl acrylate (BA) to produce end-functional polymers by a radical addition–substitution–fragmentation mechanism. The chain transfer constants (Ctr) for EBEPEP in the three monomers polymerization at 60°C were determined from measurements of the degrees of polymerization. The Ctr were determined to be 0.086, 0.91, and 0.63 in MMA, St, and BA, respectively. EBEPEP behaves nearly as an “azeotropic” transfer agent for styrene at 60°C. The activation energy, Eatr, for the chain transfer reaction of EBEPEP with PMMA radicals was determined to be 29.5 kJ/mol. Thermal stability of peroxyketal EBEPEP in the polymerization medium was estimated from the DSC measurements of the activation energy, Eath = 133.5 kJ/mol, and the rate constants, kth, of the thermolysis to various temperature. © 1994 John Wiley & Sons, Inc. 相似文献
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147.
Dr. Thibault Pariat Dr. Maxime Munch Martyna Durko-Maciag Prof. Dr. Jaroslaw Mysliwiec Dr. Pascal Retailleau Dr. Pauline M. Vérité Prof. Dr. Denis Jacquemin Dr. Julien Massue Dr. Gilles Ulrich 《Chemistry (Weinheim an der Bergstrasse, Germany)》2021,27(10):3483-3495
2-(2’-Hydroxyphenyl)benzazole (HBX) fluorophores are well-known excited-state intramolecular proton transfer (ESIPT) emitters largely studied for their synthetic versatility, photostability, strong solid-state fluorescence and ability to engineer dual emission, thus paving the way to applications as white emitters, ratiometric sensors, and cryptographic dyes. However, they are heavily quenched in solution, due to efficient non-radiative pathways taking place as a consequence of the proton transfer in the excited-state. In this contribution, the nature of the heteroring constitutive of these rigidified HBX dyes was modified and we demonstrate that this simple structural modification triggers major optical changes in terms of emission color, dual emission engineering, and importantly, fluorescent quantum yield. Investigation of the photophysical properties in solution and in the solid state of a series of ethynyl-TIPS extended HBX fluorophores, along with ab initio calculations demonstrate the very promising abilities of these dyes to act as bright dual-state emitters, in both solution (even in protic environments) and solid state. 相似文献
148.
Trimethylsilyl fluorosulfonyldifluoroacetate (TFDA): a new, highly efficient difluorocarbene reagent
William R Dolbier Jr. Feng Tian An-Rong Li Olivia Bautista J Marshall Baker Pauline Anselme Aneta Modzelewska Merle A Battiste 《Journal of fluorine chemistry》2004,125(3):459-469
TFDA is readily prepared from the reaction of fluorosulfonyldifluoroacetic acid with trimethylsilyl chloride, and it is a very effective and efficient source of difluorocarbene for use in addition reactions to alkenes of a broad scope of reactivities. Acid-sensitive substrates may require an additional purification step involving treatment of the distilled TFDA with sufficient Et3N to remove the acid impurity. Other trialkylsilyl fluorosulfonyldifluoroacetates can also be prepared, and they have been found to have reactivities similar to TFDA. The triethyl derivative, TEFDA is more convenient to prepare in a pure state and has similar reactivity to TFDA. Thus, it may prove to be a superior reagent. 相似文献
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