排序方式: 共有27条查询结果,搜索用时 15 毫秒
1.
Baker KL Stappaerts EA Gavel D Wilks SC Tucker J Silva DA Olsen J Olivier SS Young PE Kartz MW Flath LM Kruelevitch P Crawford J Azucena O 《Optics letters》2004,29(15):1781-1783
Results of atmospheric propagation for a high-speed, large-actuator-number adaptive optics system are presented. The system uses a microelectromechanical system- (MEMS-) based spatial light modulator correction device with 1024 actuators. Tests over a 1.35-km path achieved correction speeds in excess of 800 Hz and Strehl ratios close to 0.5. The wave-front sensor was based on a quadrature interferometer that directly measures phase. This technique does not require global wave-front reconstruction, making it relatively insensitive to scintillation and phase residues. The results demonstrate the potential of large-actuator-number MEMS-based spatial light modulators to replace conventional deformable mirrors. 相似文献
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Luis Martín Azucena González-Coloma Jesús Burillo Antonio M. F. Palavra José S. Urieta Ana M. Mainar 《Journal of Thermal Analysis and Calorimetry》2013,111(3):1837-1844
The aim of this study is to develop a method and to determine by means of isothermal microcalorimetry the activity of supercritical extracts obtained from growth-controlled wormwood (Artemisia absinthium L.) over Spodoptera littoralis L. (S. littoralis), a polyphagous pest of the Mediterranean crops. In order to achieve this goal, a three-step microcalorimetric method has been developed to insure the quality of the measurements and the validity of the results. Once optimized, different extracts of wormwood obtained by means of supercritical fluid extraction and by traditional methods have been used to investigate their effects over S. littoralis. The microcalorimetric method serves as a tool to complement other bioassays found in the literature. Several extracts from supercritical extractions with solvent density ranging from 485.5 to 819.5 kg m?3 have been tested. The influence of an entrainer addition to the supercritical fluid has also been investigated. The traditional extracts were obtained by hydrodistillation and organic Soxhlet extraction. The supercritical extracts were more efficient against S. littoralis than the traditionally obtained extracts. 相似文献
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Azucena O Crest J Kotadia S Sullivan W Tao X Reinig M Gavel D Olivier S Kubby J 《Optics letters》2011,36(6):825-827
We report a technique for measuring and correcting the wavefront aberrations introduced by a biological sample using a Shack-Hartmann wavefront sensor, a fluorescent reference source, and a deformable mirror. The reference source and sample fluorescence are at different wavelengths to separate wavefront measurement and sample imaging. The measurement and correction at one wavelength improves the resolving power at a different wavelength, enabling the structure of the sample to be resolved. 相似文献
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An Autocatalytic System of Photooxidation‐Driven Substitution Reactions on a FeII4L6 Cage Framework 下载免费PDF全文
Dr. Prakash P. Neelakandan Dr. Azucena Jiménez Prof. John D. Thoburn Prof. Jonathan R. Nitschke 《Angewandte Chemie (International ed. in English)》2015,54(48):14378-14382
The functions of life are accomplished by systems exhibiting nonlinear kinetics: autocatalysis, in particular, is integral to the signal amplification that allows for biological information processing. Novel synthetic autocatalytic systems provide a foundation for the design of artificial chemical networks capable of carrying out complex functions. Here we report a set of FeII4L6 cages containing BODIPY chromophores having tuneable photosensitizing properties. Electron‐rich anilines were observed to displace electron‐deficient anilines at the dynamic‐covalent imine bonds of these cages. When iodoaniline residues were incorporated, heavy‐atom effects led to enhanced 1O2 production. The incorporation of (methylthio)aniline residues into a cage allowed for the design of an autocatalytic system: oxidation of the methylthio groups into sulfoxides make them electron‐deficient and allows their displacement by iodoanilines, generating a better photocatalyst and accelerating the reaction. 相似文献
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Reina M González-Coloma A Domínguez-Díaz D Cabrera R Giménez Mariño C Rodríguez ML Villarroel L 《Natural product research》2006,20(1):13-19
A new bioactive eremophilanolide, 1alpha-tigloyloxy-8betaH,10betaH-eremophil-7(11)-en-8alpha,12-olide, was isolated from Senecio poepigii and its structure was elucidated by spectral analysis. 1alpha-Angeloyloxy-8beta-methoxy-10betaH-eremophil-7(11)-en-8alpha,12-olide was also isolated. Antifungal and insect antifeedant properties were evaluated. 相似文献
7.
Stemme F Geßwein H Drahus MD Holländer B Azucena C Binder JR Eichel RA Haußelt J Bruns M 《Analytical and bioanalytical chemistry》2012,403(3):643-650
The fabrication of novel iron-doped barium strontium titanate thin films by means of radio frequency (RF) magnetron co-sputtering is shown. Investigations of the elemental composition and the dopant distribution in the thin films obtained by X-ray photoelectron spectroscopy, Rutherford backscattering spectrometry, and time-of-flight secondary ion mass spectroscopy reveal a homogeneous dopant concentration throughout the thin film. The incorporation of the iron dopant and the temperature-dependent evolution of the crystal structure and morphology are analyzed by electron paramagnetic resonance spectroscopy, X-ray diffraction, Raman spectroscopy, atomic force microscopy, and scanning electron microscopy. In summary, these results emphasize the RF magnetron co-sputter process as a versatile way to fabricate doped thin films. 相似文献
8.
Azucena Lara-Gonzalo Eva Segovia-García Alfredo Sanz-Medel 《International journal of environmental analytical chemistry》2013,93(7):856-867
The use of two modes for mass spectrometry (MS) detection with an ion trap instrument, selected ion storage (SIS) and tandem mass spectrometry (MS/MS), are compared for the solid-phase microextraction (SPME)–gas chromatography (GC) coupled to mass spectrometry (GC-MS) determination of 16 priority organochlorine pesticides (OCPs) in drinking water samples at the ultratrace levels (ng?L?1) required by official guidelines in the European legislation. Experimental parameters investigated for the SPME sample preparation were: the type of coating (100?µm polydimethylsiloxane, PDMS, and 65?µm poly(dimethylsiloxane)–divinylbenzene, PDMS/DVB), SPME modality, extraction and desorption times and desorption temperature and the methanol percentage in the SPME working solution. Under the calculated optimal conditions two methodologies were developed, one for SIS and the other for MS/MS modes. The detection limits, precision and accuracy were evaluated for both alternatives and were appropriate to the official guidelines requirements. The SPME–GC-MS(SIS) methodology offered LODs from 0.2–6.6?ng?L?1, precision below 13% and recoveries between 83 and 110%. The SPME–GC–MS/MS methodology provided limits of detection (LODs) ranging from 0.3 to 7.6 ng?L?1, % RSD were ≤14% and recoveries of 79–108% were achieved. After the results observed within an Interlaboratory Exercise, the latest MS methodology was selected for the pursued analysis in real drinking water samples. Also, the good results in this round-robin exercise validate the proposed SPME–GC–MS/MS methodology. 相似文献
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Tao X Fernandez B Azucena O Fu M Garcia D Zuo Y Chen DC Kubby J 《Optics letters》2011,36(7):1062-1064
Optical aberrations due to the inhomogeneous refractive index of tissue degrade the resolution and brightness of images in deep-tissue imaging. We introduce a confocal fluorescence microscope with adaptive optics, which can correct aberrations based on direct wavefront measurements using a Shack-Hartmann wavefront sensor with a fluorescent bead used as a point source reference beacon. The results show a 4.3× improvement in the Strehl ratio and a 240% improvement in the signal intensity for fixed mouse tissues at depths of up to 100 μm. 相似文献
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Oriented Circular Dichroism Analysis of Chiral Surface‐Anchored Metal–Organic Frameworks Grown by Liquid‐Phase Epitaxy and upon Loading with Chiral Guest Compounds 下载免费PDF全文
Zhi‐Gang Gu Dr. Jochen Bürck Dr. Angela Bihlmeier Dr. Jinxuan Liu Dr. Osama Shekhah Dr. Peter G. Weidler Dr. Carlos Azucena Zhengbang Wang Stefan Heissler Dr. Hartmut Gliemann Prof. Dr. Wim Klopper Prof. Dr. Anne S. Ulrich Prof. Dr. Christof Wöll 《Chemistry (Weinheim an der Bergstrasse, Germany)》2014,20(32):9879-9882
Oriented circular dichroism (OCD) is explored and successfully applied to investigate chiral surface‐anchored metal–organic frameworks (SURMOFs) based on camphoric acid (D‐ and Lcam) with the composition [Cu2(Dcam)2x(Lcam)2?2x(dabco)]n (dabco=1,4‐diazabicyclo‐[2.2.2]‐octane). The three‐dimensional chiral SURMOFs with high‐quality orientation were grown on quartz glass plates by using a layer‐by‐layer liquid‐phase epitaxy method. The growth orientation, as determined by X‐ray diffraction (XRD), could be switched between the [001] and [110] direction by using either OH‐ or COOH‐terminated substrates. These SURMOFs were characterized by using OCD, which confirmed the ratio as well as the orientation of the enantiomeric linker molecules. Theoretical computations demonstrate that the OCD band intensities of the enantiopure [Cu2(Dcam)2(dabco)]n grown in different orientations are a direct result of the anisotropic nature of the chiral SURMOFs. Finally, the enantiopure [Cu2(Dcam)2(dabco)]n and [Cu2(Lcam)2(dabco)]n SURMOFs were loaded with the two chiral forms of ethyl lactate [(+)‐ethyl‐D ‐lactate and (?)‐ethyl‐L ‐lactate)]. An enantioselective enrichment of >60 % was observed by OCD when the chiral host scaffold was loaded from the racemic mixture. 相似文献