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51.
通过水热法合成了一系列水合氧化锆,以之为载体采用浸渍法制备了Pt/WO3-ZrO2催化剂,考察了氢氧化锆的水热温度对Pt/WO3-ZrO2异构化活性的影响.通过X射线衍射、NH3程序升温脱附及H2程序升温还原表征了样品的晶相结构、酸性及还原性能.结果表明,水合氧化锆及以此为载体的催化剂的晶相结构均随着氢氧化锆水热温度的变化而变化,水热温度升高,四方相氧化锆比例下降.具有一定晶相结构的水合氧化锆为载体的催化剂具有较无定形氢氧化锆为载体的催化剂更多的强酸中心和更高的异构化催化活性.高的异构化活性可能与催化剂上更多的强酸中心有关。 相似文献
52.
A new electrochemical immunosensor for the detection of α‐1‐fetoprotien (AFP) was developed based on AFP antibody (anti‐AFP)‐functionalized organic/inorganic hybrid nanocomposite membrane. To fabricate such a hybrid composite membrane, 3,4,9,10‐perylenetetracarboxylic acid‐bound thionine molecules (PTCTH) were initially doped into titania colloids (TiO2), and then gold nanoparticles and anti‐AFP were immobilized onto the composite film in turn. Comparison with the electrode fabricated only with thionine not 3,4,9,10‐perylenetetracarboxylic acid, the immunosensor with PTCTH exhibited high sensitivity and fast electron transfer. The presence of gold nanoparticles provided a good microenvironment for the immobilization of biomolecules, enhanced the surface coverage of protein, and improved the sensitivity of the immunosensor. The modified process was characterized by scanning electron microscope (SEM), cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS). The surface topography of the membrane was investigated by scanning electron microscopy (SEM). Under optimal conditions, the proposed immunosensor exhibited a wide linear range from 2.5 to 200.0 ng/mL towards AFP with a detection limit of 0.5 ng/mL (S/N=3). The stability, reproducibility and precision of the immunosensor were acceptable. Comparison with the conventional enzyme‐linked immunosorbent assay (ELISA), the present method did not require more labeled procedures and washing steps. Significantly, the detection methodology provides a promising approach for other proteins or biosecurities. 相似文献
53.
We study classes of mappings which do not belong to the QRT family. We obtain several integrable non-autonomous forms of these mappings extending previous results where only linearisable cases were found. Using our recently introduced method of singularity confinement with full deautonomisation, we analyse a mapping which, while non-integrable, does possess confined singularities and show that our method makes it possible to obtain the exact value of its algebraic entropy. 相似文献
54.
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56.
Zhenkang Wang Xiaowei Shen Sijie Li Yuxuan Wu Tingzhou Yang Jie Liu Tao Qian Chenglin Yan 《Journal of Energy Chemistry》2022,(1):496-502
The high degree of crystallinity of discharging in termediates of Li-S batteries(Li2S2/Li2S)causes a severe capacity attenuation at low temperatures.Herein,a sulfur-rich polymer is fabricated,which enables all the discharging in termediates to exist in an amorphous state without long-range order,promoti ng the substantial conversion of discharging intermediates and enhancing Li-S batteries'performance at low temperatures greatly.This cathode material exhibits excellent performance both at room and low temperatures.Even under an extremely low temperature(-40℃),the discharge capacity can remain 67% of that at room temperature.Besides,in-situ UV/Vis spectroscopy and density functional theory calculations reveal that this organosulfur cathode undergoes a new mechanism during discharge.Li2S6 and Li2S3 are the primary discharging intermediates that are quite different from conventional Li-S batteries.These results provide a new directi on for a broader range of applications of Li-S batteries. 相似文献
57.
Giada Basile Cédric Bernardin Stefano Olla 《Communications in Mathematical Physics》2009,287(1):67-98
We introduce a model whose thermal conductivity diverges in dimension 1 and 2, while it remains finite in dimension 3. We
consider a system of oscillators perturbed by a stochastic dynamics conserving momentum and energy. We compute thermal conductivity
via Green-Kubo formula. In the harmonic case we compute the current-current time correlation function, that decay like t
−d/2 in the unpinned case and like t
−d/2–1 if an on-site harmonic potential is present. This implies a finite conductivity in d ≥ 3 or in pinned cases, and we compute it explicitly. For general anharmonic strictly convex interactions we prove some upper
bounds for the conductivity that behave qualitatively as in the harmonic cases. 相似文献
58.
Yaxi Liu Ruo Yuan Yaqin Chai Chenglin Hong Kaige Liu Shu Guan 《Mikrochimica acta》2009,167(3-4):217-224
An immunosensor has been fabricated for direct amperometric determination of carcinoembryonic antigen. It is based on a biocompatible composite film composed of porous chitosan (pChit) and gold nanoparticles (GNPs). Firstly, a pChit film was formed on a glassy carbon electrode by means of electrodeposition. Then, thionine as a redox probe was immobilized on the pChit film modified electrode using glutaraldehyde as a cross-linker. Finally, GNPs were adsorbed on the electrode surface to assemble carcinoembryonic antibody (anti-CEA). The surface morphology of the pChit films was studied by means of a scanning electron microscope. The immunosensor was further characterized by cyclic voltammetry and electrochemical impedance spectroscopy. The electrochemical behaviors and factors influencing the performance of the resulting immunosensors were studied in detail. Results showed that the pChit films can enhance the surface coverage of antibodies and improve the sensitivity of the immunosensor. Under optimal conditions, the immunosensor was highly sensitive to CEA with a detection limit of 0.08 ng·mL?1 at three times the background noise and linear ranges of 0.2~10.0 ng·mL?1 and 10.0~160 ng·mL?1. Moreover, the immunosensor exhibited high selectivity, good reproducibility and stability. 相似文献
59.
Michael B. Beverly Franco Basile Kent J. Voorhees Ted L. Hadfield 《Journal of the American Society for Mass Spectrometry》1999,10(8):747-758
Free fatty acid profiling of whole bacteria [Francisella tularensis, Brucella melitensis, Yersinia pestis, Bacillus anthracis (vegetative and sporulated), and Bacillus cereus] was carried out with direct probe mass spectrometry under 70-eV electron ionization (EI) and isobutane chemical ionization in both the positive (CI+) and negative modes (CI-). Electron ionization produced spectra that contained molecular ions and fragment ions from various free fatty acids. Spectra acquired with isobutane chemical ionization in the positive mode yielded molecular ions of free fatty acids as well as ions from other bacterial compounds not observed under EI conditions. Spectra obtained with negative chemical ionization did not contain as much taxonomic information as EI or CI+; however, some taxonomically significant compounds such as dipicolinic acid and poly(3-hydroxybutyrate) did produce negative ions. All ionization modes yielded spectra that could separate the bacteria by Gram-type when observed with principle components analysis (PCA). Chemical ionization in the positive ion mode produced the greatest amount of differentiation between the four genera of bacteria when the spectra where examined by PCA. 相似文献
60.
Basile F. E. Curchod Federica Agostini Ivano Tavernelli 《The European Physical Journal B - Condensed Matter and Complex Systems》2018,91(7):168
Upon photoexcitation by a short light pulse, molecules can reach regions of the configuration space characterized by strong nonadiabaticity, where the motion of the nuclei is strongly coupled to the motion of the electrons. The subtle interplay between the nuclear and electronic degrees of freedom in such situations is rather challenging to capture by state-of-the-art nonadiabatic dynamics approaches, limiting therefore their predictive power. The Exact Factorization of the molecular wavefunction, though, offers new perspectives in the solution of this longstanding issue. Here, we investigate the performance of a mixed quantum/classical (MQC) limit of this theory, named Coupled Trajectory-MQC, which was shown to reproduce the excited-state dynamics of small systems accurately. The method is applied to the study of the photoinduced ring opening of oxirane and the results are compared with two other nonadiabatic approaches based on different Ansätze for the molecular wavefunction, namely Ehrenfest dynamics and Ab Initio Multiple Spawning (AIMS). All simulations were performed using linear-response time-dependent density functional theory. We show that the CT-MQC method can capture the (de)coherence effects resulting from the dynamics through conical intersections, in good agreement with the results obtained with AIMS and in contrast with ensemble Ehrenfest dynamics. 相似文献