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K. Acharyya R.L. Caravan R.J. Shannon M.A. Blitz D.E. Heard 《Molecular physics》2015,113(15-16):2243-2254
Recent laboratory experiments using a pulsed Laval nozzle apparatus have shown that reactions between a neutral molecule and the radical OH can occur efficiently at low temperatures despite activation energy barriers if there is a hydrogen-bonded complex in the entrance channel which allows the system to tunnel efficiently under the barrier. Since OH is a major radical in the interstellar medium, this class of reactions may well be important in the chemistry that occurs in the gas phase of interstellar clouds. Using a new gas-grain chemical network with both gas-phase reactions and reactions on the surfaces of dust particles, we studied the role of OH–neutral reactions in dense interstellar clouds at 10, 50, and 100 K. We determined that at least one of these reactions can be significant, especially at the lowest temperatures studied, where the rate constants are large. It was found in particular that the reaction between CH3OH and OH provides an effective and unambiguous gas-phase route to the production of the gaseous methoxy radical (CH3O), which has been recently detected in cold, dense interstsellar clouds. The role of other reactions in this class is explored. 相似文献
34.
Benoît Driesschaert Philippe Levêque Bernard Gallez Jacqueline Marchand-Brynaert 《Tetrahedron letters》2013
A stable RGD-conjugated triarylmethyl (TAM) radical 3 has been synthesized in a straightforward three-step sequence. CT-03 ‘the Finland trityl’ which is a very popular contrast agent for electron paramagnetic resonance imaging has been covalently bound to the NH2-ending of a pentapeptide commonly used to target integrins and confers tissue selectivity. Moreover, this new TAM radical is stable and sensitive to molecular oxygen. 相似文献
35.
Improving Site‐Directed RNA Editing In Vitro and in Cell Culture by Chemical Modification of the GuideRNA 下载免费PDF全文
Paul Vogel Marius F. Schneider Jacqueline Wettengel Dr. Thorsten Stafforst 《Angewandte Chemie (International ed. in English)》2014,53(24):6267-6271
Adenosine‐to‐inosine deamination can be re‐addressed to user‐defined mRNAs by applying phosphothioate/2′‐methoxy‐modified guideRNAs. Dense chemical modification of the guideRNA clearly improves performance of the covalent conjugates inside the living cell. Furthermore, careful positioning of a few modifications controls editing selectivity in vitro and was exploited for the challenging repair of the Factor 5 Leiden missense mutation. 相似文献
36.
Jacqueline E. Cloud Dr. Yonglong Wang Tara S. Yoder Lauren W. Taylor Prof. Yongan Yang 《Angewandte Chemie (International ed. in English)》2014,53(52):14527-14532
The synthesis of colloidal nanocrystals (NCs) of lithiated group 14 elements (Z=Si, Ge, and Sn) is reported, which are Li4.4Si, Li3.75Si, Li4.4Ge, and Li4.4Sn. LixZ compounds are highly reactive and cannot be synthesized by existing methods. The success relied on separating the surface protection from the crystal formation and using a unique passivating ligand. Bare LixZ crystals were first produced by milling elemental Li and Z in an argon‐filled jar. Then, under the assistance of additional milling, hexyllithium was added to passivate the freshly generated LixZ NCs. This ball‐milling‐assisted surface protection method may be generalized to similar systems, such as NaxZ and KxZ. Moreover, Li4.4Si and Li4.4Ge NCs were conformally encapsulated in carbon fibers, providing great opportunities for studying the potential of using LixZ to mitigate the volume‐fluctuation‐induced poor cyclability problem confronted by Z anodes in lithium‐ion batteries. 相似文献
37.
Thierry Boxus Michle Deldime-Rubbens Patrick Mougenot Yves-Jacques Schneider Jacqueline Marchand-Brynaert 《先进技术聚合物》1996,7(7):589-598
Poly(ethylene terephthalate) (PET) films and track-etched microporous membranes naturally display, on their surfaces, reactive chain-ends, i.e. carboxyl and hydroxyl functions. These were assayed by suitable activation (reaction with carbodiimide and tosyl chloride, respectively), followed by coupling with 3H-lysine and liquid scintillation counting of the sample-associated radioactivity. Values ranging between 5 and 30 pmol/cm2 (open surface) of labeled end-groups were obtained, depending on the physico-chemical nature of the samples. Basic hydrolysis enriched the PET films with both types of endings (15–25 pmol/cm2). Reduction of films with the NaBH4-catechol complex in tetrahydrofuran enriched their surfaces with hydroxyl groups. However, this procedure was not readily applicable to the surface modification of membranes; we observed an erosion effect that was confirmed by scanning electron microscope analyses. In contrast with the reduction process, the oxidation with KMnO4 in 1.2N H2SO4 could be easily applied to the modification of either films or membranes; their surfaces were significantly enriched with carboxyl groups (15–50 pmol/cm2). This surface modification strategy has been used for the covalent coupling of adhesive proteins on PET membranes developed as supports for cell cultivation. 相似文献
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Jacqueline Destain Patrick Fickers Frédéric Weekers Benoît Moreau Philippe Thonart 《Applied biochemistry and biotechnology》2005,121(1-3):269-277
In this article, we report the development and optimization of an industrial culture medium for the production of extracellular
lipase in the yeast Yarrowia lipolytica. Until now olive oil in combination with glucose was used as the carbon source and inducer for the production of lipase.
Our results demonstrate that methyloleate, a cheap hydrophobic compound, could efficiently substitute olive oil as the inducer
and carbon source for lipase production. A new process of lipase production was developed yielding a twofold increase in the
level of production compared with the levels in previous reports. 相似文献
40.
Jacqueline L. Stroud Steve P. McGrath 《International journal of environmental analytical chemistry》2013,93(2):222-236
Selenium (Se) speciation in soil affects its bioavailability to crops. An analytical procedure for the determination of inorganic Se species (selenite and selenate) in soil extracts by anion-exchange liquid chromatography (LC) with ICP-MS detection has been developed, with 10-fold higher sensitivity than existing HGAAS-based soil Se measurements. A comparison of phosphate extraction solutions on agricultural soils amended with 20?µg?kg–1 selenate or selenite was carried out, and a 0.016?M?KH2PO4 extraction solution is recommended. Recovery of selenate was >91%; however, selenite recovery ranged between 18.5% and 46.1%, due to rapid binding to the soil. Soil preparation did not have a significant (p?>?0.05) effect on the extractability of the selenate or selenite amendments. The stability of Se species in the phosphate extracts was variable, depending on temperature and storage time. Therefore, immediate (<1?h) analysis of the soil extracts is preferable. The method developed was applied to the determination of extractable Se from six arable soils in the UK. Extractable Se levels in these soils ranged between 6 and 13?µg?kg–1 consisting of selenite and some soluble organic Se. 相似文献