Molecular hydrogen evolution catalysts (HECs) are synthetically tunable and often exhibit high activity, but they are also hampered by stability concerns and practical limitations associated with ...their use in the homogeneous phase. Their incorporation as integral linker units in metal–organic frameworks (MOFs) can remedy these shortcomings. Moreover, the extended three-dimensional structure of MOFs gives rise to high catalyst loadings per geometric surface area. Herein, we report a new MOF that exclusively consists of cobaloximes, a widely studied HEC, that act as metallo-linkers between hexanuclear zirconium clusters. When grown on conducting substrates and under applied reductive potential, the cobaloxime linkers promote electron transport through the film as well as function as molecular HECs. The obtained turnover numbers are orders of magnitude higher than those of any other comparable cobaloxime system, and the molecular integrity of the cobaloxime catalysts is maintained for at least 18 h of electrocatalysis. Being one of the very few hydrogen evolving electrocatalytic MOFs based on a redox-active metallo-linker, this work explores uncharted terrain for greater catalyst diversity and charge transport pathways.
•A two-lane lattice model is proposed by considering the density difference effect.•Linear and non-linear stability analyses are conducted.•Effects of lane change and reaction coefficient are ...examined.
In this paper, a modified lattice hydrodynamic model of traffic flow is proposed by considering the density difference between leading and following lattice for two-lane system. The effect of density difference on the stability of traffic flow is examined through linear stability analysis and shown that the density difference term can significantly enlarge the stability region on the phase diagram. To describe the phase transition of traffic flow, the Burgers equation and mKdV equation near the critical point are derived through nonlinear analysis. To verify the theoretical findings, numerical simulation is conducted which confirms that traffic jam can be suppressed efficiently by considering the density difference effect in the modified lattice model for two-lane traffic.
Abstract With dedicated exoplanet surveys underway for multiple extreme-precision radial velocity (EPRV) instruments, the near-future prospects of RV exoplanet science are promising. These surveys’ ...generous time allocations are expected to facilitate the discovery of Earth analogs around bright, nearby Sun-like stars. But survey success will depend critically on the choice of observing strategy, which will determine the survey’s ability to mitigate known sources of noise and extract low-amplitude exoplanet signals. Here we present an analysis of the Fisher information content of simulated EPRV surveys, accounting for the most recent advances in our understanding of stellar variability on both short and long timescales (i.e., oscillations and granulation within individual nights, and activity-induced variations across multiple nights). In this analysis, we capture the correlated nature of stellar variability by parameterizing these signals with Gaussian process kernels. We describe the underlying simulation framework and the physical interpretation of the Fisher information content, and we evaluate the efficacy of EPRV survey strategies that have been presented in the literature. We explore and compare strategies for scheduling observations over various timescales, and we make recommendations to optimize survey performance for the detection of Earth-like exoplanets.
We study a deterministic framework for important cellular transport phenomena involving a large number of interacting molecules called the excluded flow of extended interacting objects with drop-off ...effect (EFEIOD). This model incorporates many realistic features of biological transport process including the length of biological "particles" and the fact that they can detach along the biological 'tracks'. The flow between the consecutive sites is unidirectional and is described by a "soft" simple exclusion principle and by repelling or attracting forces between neighboring particles. We show that the model admits a unique steady-state. Furthermore, if the parameters are periodic with common period T, then the steady-state profile converge to a unique periodic solution of period T. Simulations of the EFEIOD demonstrate several non-trivial effects of the interactions on the system steady-state profile. For example, detachment rates may help in increasing the steady-state flow by alleviating traffic jams that can exist due to several reasons like bottleneck rate or interactive forces between the particles. We also analyze the special case of our model, when there are no forces exerted by neighboring particles, and called it as the ribosome flow model of extended objects with drop-off effect (RFMEOD), and study the sensitivity of its steady-state to variations in the parameters.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
Inspired by different stochastic mechanisms, such as the two-sided motion of ribosomes seen during the initiation of mRNA translation, which is backed by their decay, we investigate a totally ...asymmetric simple exclusion process with open boundaries in a bidirectional setting where two oppositely charged species of particles move opposite to each other and locally reset to the respective entry site. The steady-state characteristics, such as density profiles and phase diagrams, are investigated theoretically under the mean-field framework. The introduction of resetting into the system produces non-trivial effects in the form of two novel asymmetric phases that appear in the phase diagram. The system possesses several different combinations of symmetric phases as well as asymmetric phases for different resetting rates. A rich behavior is observed in the system, emphasizing the occurrence of spontaneous symmetry-breaking phenomena even in the small resetting regime. Moreover, the significance of the resetting rate is analyzed on the domain wall, and it is found that one of the stationary phases with a localized domain wall vanishes for a substantial resetting rate. Due to the interaction of both species at the boundaries, the consequences of the resetting dynamics on the boundary densities are also investigated. All the findings, including finite-system size, are thoroughly validated by the Monte Carlo simulations.
Ending the fossil fuel era towards a sustainable future will require high-performing renewable materials with a low environmental impact. Carbon black, produced by partial combustion or thermal ...decomposition of petroleum hydrocarbons, is by far the most dominant filler of rubber composites, followed by mineral fillers (
e.g.
silica, talc, clay, calcium carbonate,
etc
.). However, the manufacture of carbon black has a considerable carbon footprint. Similarly, mineral fillers also do not come without challenges, including poor compatibility with rubber matrices and high density. Consequently, the need for sustainable and green fillers with a low or even zero carbon footprint has dramatically increased. In recent years, plant-derived sustainable materials, such as cellulose nanocrystals, natural fibers, lignin, biochar, polysaccharides,
etc
., have been extensively investigated as substitute or complementary fillers of rubbers. In this work, we critically reviewed recent developments in the innovation and utilization of sustainable biofillers for rubber composite applications, emphasizing the effect of the filler on the structure-processing-property relationships in rubber composites. A wide range of biofillers with an array of structure, morphology, and physico-chemical properties and their various attributes in different rubbers are intensively reviewed and discussed. Effective preparation strategies and surface modification platforms on the different biofillers to develop high-performance sustainable rubber biocomposites were critically reviewed. Finally, future perspectives for biofillers in rubber composite applications and challenges are discussed.
This article reviewed the recent progress in the development and utilization of sustainable biofillers for rubber composite applications, emphasizing the effect of the filler on the structure-processing-property relationship of rubber composites.
We report the functionalization and deplanarization of truxenes using pnictaalkene fragments. Selective introduction of one, two, or three Mes*‐Pn fragments provides up to three fully reversible ...reductions based on the Pn=C fragments. The incorporation of the unsaturated heteroelement fragment as well as the contortion of the truxene core result in significantly red‐shifted absorption spectra and interesting opto‐electronic properties which are studied by electrochemistry and spectro‐electrochemistry. Incorporation of arsaalkene (As=C) motifs gives significantly milder reduction potentials and red‐shifted absorption, while phosphaalkene decorated truxene P3 can be functionalized using Au(I)Cl coordination. Furthermore, solubility is markedly increased upon incorporation of the Pn‐Mes* fragments which renders these materials suitable for solution processing.
Putting the contortion back into the truxene fragments. Substitution of the methylene fragments by strongly electron accepting phosphaalkene or arsaalkenes provides new tuning opportunities for twisted PAHs.
Abstract
Characterizing the masses and orbits of near-Earth-mass planets is crucial for interpreting observations from future direct imaging missions (e.g., HabEx, LUVOIR). Therefore, the Exoplanet ...Science Strategy report recommended further research so future extremely precise radial velocity surveys could contribute to the discovery and/or characterization of near-Earth-mass planets in the habitable zones of nearby stars prior to the launch of these future imaging missions. Newman et al. (2023) simulated such 10 yr surveys under various telescope architectures, demonstrating they can precisely measure the masses of potentially habitable Earth-mass planets in the absence of stellar variability. Here, we investigate the effect of stellar variability on the signal-to-noise ratio (S/N) of the planet mass measurements in these simulations. We find that correlated noise due to active regions has the largest effect on the observed mass S/N, reducing the S/N by a factor of ∼5.5 relative to the no-variability scenario; granulation reduces by a factor of ∼3, while p-mode oscillations has little impact on the proposed survey strategies. We show that in the presence of correlated noise, 5 cm s
−1
instrumental precision offers little improvement over 10 cm s
−1
precision, highlighting the need to mitigate astrophysical variability. With our noise models, extending the survey to 15 yr doubles the number of Earth-analogs with mass S/N > 10, and reaching this threshold for any Earth-analog orbiting a star >0.76
M
⊙
in a 10 yr survey would require an increase in the number of observations per star from that in Newman et al. (2023).
A series of polypyridyl ruthenium(II) complexes has been synthesized and characterized by 1H‐NMR, electronic absorption and voltammetric techniques. Among this series, hexafluorophosphate salts of ...eight ruthenium(II) complexes were newly prepared. Due to the well‐known ability of this class of compounds to assist electro‐ and photocatalytic reductive processes (such as the reduction of CO2, H+ and NAD(P)+ models), particular attention has been paid to investigate the nature of their one‐ and two‐electron reduced species through computational and spectroscopic techniques.
Identifying key intermediates in catalytic processes involving Ru(tpy)(bpy)X‐type complexes is of great importance to understand mechanisms better. We provide a full set of spectroscopic and computational characterizations of the first two reduced states of a series of these complexes.
A new multi-phase lattice hydrodynamic traffic flow model is proposed by considering the effect of multi-forward looking sites on a unidirectional highway. We examined the qualitative properties of ...proposed model through linear as well as nonlinear stability analysis. It is shown that the multi-anticipation effect can significantly enlarge the stability region on the phase diagram and exhibit three-phase traffic flow. It is also observed that the multi-forward looking sites have prominent influence on traffic flow when driver senses the relative flux of leading vehicles. Theoretical findings are verified using numerical simulation which confirms that the traffic jam is suppressed efficiently by considering the information of leading vehicles in unidirectional multi-phase traffic flow.
•A multi-phase lattice model is presented by incorporating the effect of forward looking sites.•The qualitative properties of proposed model are analyzed theoretically.•Phase diagrams are presented for different parameters.•The effect of forward leading lattices on multi-phase traffic dynamics is examined numerically.
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