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981.
1 INTRODUCTIONResearchonSHGeffecthasbeenonaremarkablepositioninorganicnonlinearoptical(NLO)materialsfield.Theconjugateddelocalizedπelectronspossiblyresultinthesecond-orderNLOpropertyoforganiccompounds,soanumberofnitroanilinederivatives,suchas2-methyl… 相似文献
982.
María Natividad Pérez-Camacho Jehad Abu-Dahrieh Alexre Goguet Kening Sun David Rooney 《催化学报》2014,(8)
Gas-to-liquid processes are generally used to convert natural gas or other gaseous hydrocarbons into liquid fuels via an intermediate syngas stream. This includes the production of liquid fuels from biomass‐derived sources such as biogas. For example, the dry reforming of methane is done by reacting CH4 and CO2, the two main components of natural biogas, into more valuable products, i.e.,CO and H2. Nickel containing perovskite type catalysts can promote this reaction, yielding good conversions and selectivities; however, they are prone to coke laydown under certain operating conditions. We investigated the addition of high oxygen mobility dopants such as CeO2, ZrO2, or YSZ to reduce carbon laydown, particularly using reaction conditions that normally result in rapid cok‐ing. While doping with YSZ, YDC, GDC, and SDC did not result in any improvement, we show that a Ni perovskite catalyst (Na0.5La0.5Ni0.3Al0.7O2.5) doped with 80.9 ZrO2 15.2 CeO2 gave the lowest amount of carbon formation at 800 °C and activity was maintained over the operating time. 相似文献
983.
Ye Feng XueShan Zhao LiJun Gou YuFeng Li James FSteiner Javier AGarc´ıa Yuan Wang Nan Jia ZhenXuan Liao HuiXian Li 《中国科学:物理学 力学 天文学(英文版)》2022,(1)
AT2019 wey is a new galactic X-ray binary that was first discovered as an optical transient by the Asteroid Terrestrial-impact Last Alert System(ATLAS)on December 7,2019.AT2019 wey consists of a black hole candidate as well as a low-mass companion star(Mstar≤1.0 M■)and is likely to have a short orbital period(Porb≤16h).Although AT2019 wey began activation in the X-ray band on March 8,2020,it did not enter the soft state during almost the entire outburst.In this study,we present a detailed spectral analysis of AT2019 wey in the low/hard state during its X-ray outburst on the basis of Nuclear Spectroscopic Telescope Array(Nu S T AR)observations.We obtain tight constraints on several of its important physical parameters by applying the state of the art relxill relativistic reflection model family.In particular,we determine that the measured inner radius of the accretion disk is most likely to have extended to the innermost stable circular orbit(ISCO)radius,i.e.,Rin=1.38+0.23-0.16RISCO.Hence,assuming Rin=RISCO,we find the spin of AT2019 wey to be a*~0.97,which is close to the extreme and an inner disk inclination angle of i~22°.Additionally,according to our adopted models,AT2019 wey tends to have a relatively high iron abundance of AFe~5AFe,■and a high disk ionization state of logξ~3.4. 相似文献
984.
In this paper, we characterize the odd positive integers n satisfying the congruence∑n -1 j=1 j n-1/2 ≡ 0 (mod n). We show that the set of such positive integers has an asymptotic density which turns out to be slightly larger than 3/8. 相似文献
985.
In this paper, a recently introduced cellular automata (CA) model is used for a statistical analysis of the inner micro-scopic structure of synchronized traffic flow. The analysis focuses on the formation and dissolution of clusters or platoons of vehicles, as the mechanism that causes the presence of this synchronized traffic state with a high flow. This platoon formation is one of the most interesting phenomena observed in traffic flows and plays an important role both in manual and automated highway systems (AHS). Simulation results, obtained from a single-lane system under periodic boundary conditions indicate that in the density region where the synchronized state is observed, most vehicles travel together in pla- toons with approximately the same speed and small spatial distances. The examination of velocity variations and individual vehicle gaps shows that the flow corresponding to the synchronized state is stable, safe and highly correlated. Moreover, results indicate that the observed platoon formation in real traffic is reproduced in simulations by the relation between vehicle headway and velocity that is embedded in the dynamics definition of the CA model. 相似文献
986.
We present fine-structure-resolved collisional rate coefficients for the NH(X(3)Σ(-))-He van der Waals complex. The calculations are based on the state-of-the-art potential energy surface [Cybulski et al., J. Chem. Phys. 122, 094307 (2005)]. Close-coupling calculations of the collisional excitation cross sections of the fine-structure levels of NH by He are calculated for total energies up to 3500 cm(-1), which yield, after thermal average, rate coefficients up to 350 K. The fine-structure splitting of rotational levels is taken into account rigorously. The propensity rules between fine-structure levels are reported, and it is found that F-conserving cross sections are much larger than F-changing cross sections, as expected from theoretical considerations. The calculated rate coefficients are compared with available experimental measurements at room temperature and a fairly good agreement is found between experimental and theoretical data. The agreement confirms the relatively good quality of the scattering calculations and also the accuracy of the potential energy surface used in this work. The new set of thermal rate coefficients for this system may be used for improvements in astrophysical and atmospherical modeling. 相似文献
987.
Cerveny S Arrese-Igor S Dolado JS Gaitero JJ Alegría A Colmenero J 《The Journal of chemical physics》2011,134(3):034509
The behavior of water dynamics confined in hydrated calcium silicate hydrate (C-S-H) gel has been investigated using broadband dielectric spectroscopy (BDS; 10(-2)-10(6) Hz) in the low-temperature range (110-250 K). Different water contents in C-S-H gel were explored (from 6 to 15 wt%) where water remains amorphous for all the studied temperatures. Three relaxation processes were found by BDS (labeled 1 to 3 from the fastest to the slowest), two of them reported here for the first time. We show that a strong change in the dielectric relaxation of C-S-H gel occurs with increasing hydration, especially at a hydration level in which a monolayer of water around the basic units of cement materials is predicted by different structural models. Below this hydration level both processes 2 and 3 have an Arrhenius temperature dependence. However, at higher hydration level, a non-Arrhenius behavior temperature dependence for process 3 over the whole accessible temperature range and, a crossover from low-temperature Arrhenius to high-temperature non-Arrhenius behavior for process 2 are observed. Characteristics of these processes will be discussed in this work. 相似文献
988.
Glycogen synthase kinase-3 (GSK-3) targets encompass proteins implicated in AD and neurological disorders. The functions of
GSK-3 and its implication in various human diseases have triggered an active search for potent and selective GSK-3 inhibitors.
In this sense, QSAR could play an important role in studying these GSK-3 inhibitors. For this reason, we developed QSAR models
for GSK−3α, linear discriminant analysis (LDA), and artificial neural networks (ANNs) from nearly 50,000 cases with more than 700 different
GSK−3α inhibitors obtained from ChEMBL database server; in total we used more than 20,000 different molecules to develop the QSAR
models. The model correctly classified 237 out of 275 active compounds (86.2%) and 14,870 out of 15,970 non-active compounds
(93.2%) in the training series. The overall training performance was 93.0%. Validation of the model was carried out using
an external predicting series. In these series, the model classified correctly 458 out of 549 (83.4%) compounds and 29,637
out of 31,927 non-active compounds (83.4%). The overall predictability performance was 92.7%. In this study, we propose three
types of non-linear ANN as alternative to already existing models, such as LDA. Linear neural network: LNN: 236:236-1-1:1
which had an overall training performance of 96% proved to be the best model. In addition, we did a study of the different
fragments of the molecules of the database to see which fragments had more influence in the activity. This can help design
new inhibitors of GSK−3α. This study reports the attempts to calculate, within a unified framework probabilities of GSK−3α inhibitors against different molecules found in the literature. 相似文献
989.
Classically, optical systems are considered to have a fundamental resolution limit due to diffraction. Many strategies for
improving both axial and lateral resolutions are based on a priori information about the input signal. These strategies lead
to a numerical aperture improvement. However these are still limited by the wave nature of light. By using fluorescence technique
one theoretically can reach unlimited resolution. The key point is to use the nonlinear dependence of the fluorescence emission
rate on the intensity of the applied illumination. In this paper we present simulation as well as experimental results which
show the advantage and the problems of using the nonlinear fluorescence effect in super resolution systems as well as discussing
the nonlinear phenomena concerning the fluorescence process. The results show that the nonlinear fluorescence effect is accompanied
by severe quenching, bleaching and saturation phenomena. As consequence, super resolution using saturated structured illumination
method in living biological samples becomes severely restricted. 相似文献
990.
Pelegrín-García D 《The Journal of the Acoustical Society of America》2011,129(3):1161-1164
Recently, a paper written by Brunskog Gade, Paya?-Ballester and Reig-Calbo, "Increase in voice level and speaker comfort in lecture rooms" [J. Acoust. Soc. Am. 125, 2072-2082 (2009)] related teachers' variation in vocal intensity during lecturing to the room acoustic conditions, introducing an objective parameter called "room gain" to describe these variations. In a failed attempt to replicate the objective measurements by Brunskog et al., a simplified and improved method for the calculation of room gain is proposed, in addition with an alternative magnitude called "voice support." The measured parameters are consistent with those of other studies and are used here to build two empirical models relating the voice power levels measured by Brunskog et al., to the room gain and the voice support. 相似文献