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91.
We demonstrated a stable degenerate synchronously pumped femtosecond optical parametric oscillator (SPOPO) as a divide-by-2 subharmonic generator. The SPOPO exhibited passive all-optical self-phase-locking between the pump and signal/idler and thus required no external electronic feedback to produce the phase-locked subharmonic. We employed a type I phase-matched, 1-mm-long, periodically poled MgO:LiNbO3 crystal as the nonlinear gain element and an 80 MHz mode-locked Ti:sapphire laser with 180 fs pulses tuned at 775 nm as the pump. The SPOPO generated transform-limited 70 fs phase-locked output pulses centered at 1550 nm. The self-phase-locking operation was confirmed by separate beat-note measurement techniques with respect to the pump laser and with respect to an external cw laser. 相似文献
92.
93.
A safe, functional-group-tolerant and high-throughput version of the trimethylaluminium mediated amide bond formation reaction has been developed in a microreactor system; rimonabant and efaproxiral were prepared to illustrate the utility of the method. 相似文献
94.
Light-Responsive Elastin-Like Peptide-Based Targeted Nanoparticles for Enhanced Spheroid Penetration
Dr. Duc H. T. Le Dr. Vusala Ibrahimova Sebastian A. H. van den Wildenberg Dr. Hanglong Wu Alba Fonseca Prof. Dr. Tomas Torres Dr. Elisabeth Garanger Dr. William P. J. Leenders Prof. Dr. Roland Brock Prof. Dr. Sébastien Lecommandoux Prof. Dr. Jan C. M. van Hest 《Angewandte Chemie (International ed. in English)》2023,62(24):e202300511
We describe here a near infrared light-responsive elastin-like peptide (ELP)-based targeted nanoparticle (NP) that can rapidly switch its size from 120 to 25 nm upon photo-irradiation. Interestingly, the targeting function, which is crucial for effective cargo delivery, is preserved after transformation. The NPs are assembled from (targeted) diblock ELP micelles encapsulating photosensitizer TT1-monoblock ELP conjugates. Methionine residues in this monoblock are photo-oxidized by singlet oxygen generated from TT1, turning the ELPs hydrophilic and thus trigger NP dissociation. Phenylalanine residues from the diblocks then interact with TT1 via π-π stacking, inducing the re-formation of smaller NPs. Due to their small size and targeting function, the NPs penetrate deeper in spheroids and kill cancer cells more efficiently compared to the larger ones. This work could contribute to the design of “smart” nanomedicines with deeper penetration capacity for effective anticancer therapies. 相似文献
95.
The aim of this note is to discuss some issues posed by the emergency of universal interfaces able to decide on the truth of geometric statements. More specifically, we consider a recent GeoGebra module allowing general users to verify standard geometric theorems. Working with this module in the context of Varignon’s theorem, we were driven—by the characteristics of the GeoGebra interface—to perform a quite detailed study of the very diverse fate of attempting to automatically prove this statement, when using two different construction procedures. We highlight the relevance—for the theorem proving output—of expression power of the dynamic geometry interface, and we show that the algorithm deciding about the truth of some—even quite simple—statements can fall into a not true and not false situation, providing a source of confusion for a standard user and an interesting benchmark for geometers interested in discovering new geometric facts. 相似文献
96.
97.
Ausra Peciulyte Juris Kiskis Per Tomas Larsson Lisbeth Olsson Annika Enejder 《Cellulose (London, England)》2016,23(3):1521-1536
Enzymatic hydrolysis of cellulose provides a renewable source of monosaccharides for production of variety of biochemicals and biopolymers. Unfortunately, the enzymatic hydrolysis of cellulose is often incomplete, and the reasons are not fully understood. We have monitored enzymatic hydrolysis in terms of molecular density, ordering and autofluorescence of cellulose structures in real time using simultaneous CARS, SHG and MPEF microscopy with the aim of contributing to the understanding and optimization of the enzymatic hydrolysis of cellulose. Three cellulose-rich substrates with different supramolecular structures, pulp fibre, acid-treated pulp fibre and Avicel, were studied at microscopic level. The microscopy studies revealed that before enzymatic hydrolysis Avicel had the greatest carbon-hydrogen density, while pulp fibre and acid-treated fibre had similar density. Monitoring of the substrates during enzymatic hydrolysis revealed the double exponential SHG decay for pulp fibre and acid-treated fibre indicating two phases of the process. Acid-treated fibre was hydrolysed most rapidly and the hydrolysis of pulp fibre was spatially non-uniform leading to fractioning of the particles, while the hydrolysis of Avicel was more than an order of magnitude slower than that of both fibres. 相似文献
98.
Torres T Gouloumis A Sanchez-Garcia D Jayawickramarajah J Seitz W Guldi DM Sessler JL 《Chemical communications (Cambridge, England)》2007,(3):292-294
A new non-covalent electron transfer model system, based on the use of cytidine-guanosine hydrogen bonding interactions, is described that incorporates a phthalocyanine photodonor and a C60 fullerene acceptor. 相似文献
99.
Thiosulfinates are an emerging class of oxidized sulfur species that are frequently supposed to be involved in biochemical processes. Reaction of 12- and 10-membered ring pseudopeptidic thiosulfinates 1a (4,4,7,7-tetramethyl-1,3,4,7,8,10-hexahydro-5,6,1,10-benzodithiadiazacyclododecine-2,9-dione 5-oxide) and 1b (3,3,6,6-tetramethyl-1,8-dihydro-4,5,1,8-benzodithiadiazecine-2,7(3H,6H)-dione 4-oxide) with a Ni(II) salt leads after ring cleavage under alkaline conditions to the isolation of diamidato/thiolato/sulfinato complexes. These two thiolato/sulfinato complexes of nickel, which can also be prepared by dioxygen oxidation of the parent diamidato/dithiolato complexes, were characterized by X-ray crystallography. They show a square-planar geometry with a S-bonded sulfinato ligand. A similar reaction between 1b and a Zn(II) salt leads to a thiolato/sulfinato complex with an O-bonded sulfinate via the intermediate formation of a mixed thiolato/sulfinic ester. On the basis of 1H NMR, IR, and mass analyses, the sulfinic ester in the intermediate is proposed to be O-bonded to the zinc center. Then, an in-depth study of the cleavage of these thiosulfinates with the oxyanions RO- and HO- was performed. This led, after trapping of the open species with CH3I, to the identification of three polyfunctionalized products containing a methyl thioether, with either an isothiazolidin-3-one S-oxide, a methyl sulfone, or a methyl sulfinic ester. All of these products arise from a selective nucleophilic attack at the sulfinyl sulfur, promoted either directly by RO- or HO- or by an internal peptidic nitrogen of the thiosulfinate after deprotonation with RO- or HO-. 相似文献
100.
Wolpher H Sinha S Pan J Johansson A Lundqvist MJ Persson P Lomoth R Bergquist J Sun L Sundström V Akermark B Polívka T 《Inorganic chemistry》2007,46(3):638-651
A series of bis(terpyridine)RuII complexes have been prepared, where one of the terpyridines is functionalized in the 4'-position by a phosphonic or carboxylic acid group for attachment to TiO2. The other is functionalized, also in the 4'-position, by a potential electron donor. In complexes 1a, 3a, and 4a,b, this donor is tyrosine or hydrogen-bonded tyrosine, while in 2a it is carotenoic amide. The synthesis and photophysical properties of the complexes are discussed. On irradiation with visible light, the formation of a long-lived charge-separated state was anticipated, via primary electron ejection into the TiO2, followed by secondary electron transfer from the donor to the photogenerated RuIII. However, such a charge-separated state could be observed with certainty only with complex 2a. To explain the result, quantum chemical calculations were performed on the different types of complexes. 相似文献