Silver nanoparticles were successfully synthesized from AgNO
3 through a simple green route using the latex of
Jatropha curcas as reducing as well as capping agent. Nanoparticles were characterized ...with the help of HRTEM, X-ray diffraction and UV–vis absorption spectroscopy. X-ray diffraction analysis showed that the nanoparticles were of face centered cubic structure. A comparison of radius of nanoparticles obtained from HRTEM image with the optimized cavity radius of the cyclic peptides present within the latex revealed that the particles having radius 10–20
nm are mostly stabilized by the cyclic peptides.
Finding complex reaction and transformation pathways involving many intermediate states is, in general, not possible on the density-functional theory level with existing simulation methods, due to ...the very large number of required energy and force evaluations. For complex reactions, it is not possible to determine which atom in the reactant is mapped onto which atom in the product. Trying out all possible atomic index mappings is not feasible because of the factorial increase in the number of possible mappings. We use a penalty function that is invariant under index permutations to bias the potential energy surface in such a way that it obtains the characteristics of a structure seeker, whose global minimum is the reaction product. By performing a minima-hopping-based global optimization on this biased potential energy surface, we rapidly find intermediate states that lead into the global minimum and allow us to then extract entire reaction pathways. We first demonstrate for a benchmark system, namely, the Lennard-Jones cluster LJ_{38}, that our method finds intermediate states relevant to the lowest energy reaction pathway, and hence we need to consider much fewer intermediate states than previous methods to find the lowest energy reaction pathway. Finally, we apply the method to two real systems, C_{60} and C_{20}H_{20}, and show that the reaction pathways found contain valuable information on how these molecules can be synthesized.
The consequences of unequal propagation delay of the sampled control signals along the two arms of a class of digital tan-lock loops (DTLs) have been studied in this paper. The said delay is ...considered as a fraction of the basic sampling period and it is modeled by including a discrete time version of a unit-amplitude pure phase shift network in one of the arms of the tan-lock phase detector (PD). The DTL with such unbalanced fractional delay (named as FD-DTL) is studied through bifurcation analysis and time domain numerical simulation of the system equation. Obtained results indicate that for a FD-DTL loop gain values could be taken higher and frequency acquisition ranges (FARs) are wider compared to those for a conventional DTL (CDTL). Thus a deliberate inclusion of a fractional time delay network in one of the arms of a CDTL is a novel technique to improve its dynamical responses.
•The unequal propagation time in two arms of tan-lock phase detector is modeled as fractional delay.•Dynamics of digital tan-lock loop (DTL) with fractional delay is examined analytically and numerically.•Fractional delay of proper magnitude broadens stable zone and frequency acquisition range of the loop.•Inclusion of deliberate fractional delay may be an useful technique of high performance DTL design.
Abstract
Atomic environment fingerprints are widely used in computational materials science, from machine learning potentials to the quantification of similarities between atomic configurations. Many ...approaches to the construction of such fingerprints, also called structural descriptors, have been proposed. In this work, we compare the performance of fingerprints based on the overlap matrix, the smooth overlap of atomic positions, Behler–Parrinello atom-centered symmetry functions, modified Behler–Parrinello symmetry functions used in the ANI-1ccx potential and the Faber–Christensen–Huang–Lilienfeld fingerprint under various aspects. We study their ability to resolve differences in local environments and in particular examine whether there are certain atomic movements that leave the fingerprints exactly or nearly invariant. For this purpose, we introduce a sensitivity matrix whose eigenvalues quantify the effect of atomic displacement modes on the fingerprint. Further, we check whether these displacements correlate with the variation of localized physical quantities such as forces. Finally, we extend our examination to the correlation between molecular fingerprints obtained from the atomic fingerprints and global quantities of entire molecules.
A method for the size-controlled synthesis of silver nanoparticles is proposed and described. Synthesis is based on the reduction of AgNO
3 in aqueous SDS solution by hydrogen. These nanoparticles ...are poly-disperse in size and shape and their dimensions can be easily controlled in the range of 20 to 60 nm by varying the concentration of AgNO
3. Silver nanoparticles are analyzed using transmission electron microscope (TEM) and UV–vis spectroscopic technique. A comparison between the experimentally observed UV–vis spectra and the simulated one obtained from the modified Mie's theory, are made to understand the nature of shift of the SPR band.
Using fingerprints used mainly in machine learning schemes of the potential energy surface, we detect in a fully algorithmic way long range effects on local physical properties in a simple covalent ...system of carbon atoms. The fact that these long range effects exist for many configurations implies that atomistic simulation methods, such as force fields or modern machine learning schemes, that are based on locality assumptions, are limited in accuracy. We show that the basic driving mechanism for the long range effects is charge transfer. If the charge transfer is known, locality can be recovered for certain quantities such as the band structure energy.
Capital Markets in India, which features a distinctive and eclectic list of authors who represent the best in their respective fields. provides a comprehensive picture of the recent trends and ...developments in the Indian finance scenario.
Abstract We theoretically investigate a N -type 87 Rb atomic system for efficient generation and control of a non-degenerate four wave mixing (FWM) signal in pulsed regime. The susceptibility of the ...atomic medium is customized as a gain profile by a weak probe pulse and two strong continuous wave control fields which allow us to generate the pulsed FWM signal. We study the propagation dynamics of the generated FWM signal inside the nonlinear medium. The FWM signal obtains the exact shape of the probe pulse and travels without changing the shape whereas, the probe pulse is absorbed inside the nonlinear medium. The conversion efficiency of this scheme without a MW field is 5.36%. However, a MW field that couples two metastable ground states enhances the conversion efficiency to 20.6%. The generation and control of such FWM signal in pulsed regime has important applications in signal processing, optical communication and information science.
Stabilization of different morphologies of iso-material native/non-native heterostructures is important for electron–hole separation in the context of photo-electrochemical and opto-electronic ...devices. In this regard, we explore the stabilities of different morphologies of rutile (“native”, ground state phase) and anatase (“non-native” phase) TiO2 heterostructures through (1) seed-mediated growth and (2) a thermally induced arrested phase transition synthesis protocol. Furthermore, the experimental results are analyzed through a combination of Density Functional Tight Binding (DFTB) and Finite Element Model (FEM) methods. During the seed-mediated growth, anatase is grown over a polydispersed and polycrystalline rutile core through thermal treatment yielding core–shell, Janus and yolk–shell iso-material heterostructures as observed from HRTEM. The arrested phase transition of anatase to rutile at different annealing temperatures yields rutile crystals in the subsurface region of the anatase and rutile/core-thin anatase/shell heterostructures but does not yield a Janus structure. Small particles that can be modeled via DFTB computations suggest that: (1) a heterostructure of the rutile/core-anatase/shell is energetically more stable than the anatase/core-rutile/shell or any other Janus configuration, (2) the off-centered rutile/core–anatase shell is more favorable to the mid-centered rutile/core–anatase shell and (3) Janus heterostructures can be stabilized when the mass ratio of the rutile seed to anatase overgrowth is high. FEM simulations, performed to evaluate the importance of stress relaxation in bicrystalline materials without defects, suggest that Janus structures can be stabilized in larger particles. The present studies add to the heuristics available for synthesizing iso-material heterostructures.
When Are Investors Rational? Mukherjee, Saptarshi; De, Sankar
The journal of behavioral finance,
01/2019, Letnik:
20, Številka:
1
Journal Article
Recenzirano
Taking our cue from certain recent advances in experimental psychology, the authors propose a plausible theory of conflict between rationality and inherent behavioral biases of investors. In this ...theory no investor is fully rational or fully behavioral at all times. An investor faces a continuum between behavioral and rational positions. A movement toward rationality is a choice; it is costly to be fully rational which requires serious mental calculations. On the other hand, there could be some benefits to rationality in special circumstances that compensate for the costs. Using a unique and extensive investor-level database, the authors show that the degree of nonrationality decreases as rational behavior becomes more attractive. In the empirical setting, the proxy for rational behavior is investor's use of private predisclosure information during earnings announcement periods, while the disposition effect they display serves as an estimate of their behavioral bias. The paper contributes to the existing literature in several dimensions.
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