Considerable Theoretical Research Research Articles

Electrocatalytic CO2 reduction towards industrial applications

AbstractRecently, research on the electrocatalytic CO2 reduction reaction (eCO2RR) has attracted considerable attention due to its potential to resolve environmental problems caused by CO2 while utilizing clean energy and producing high‐value‐added products. Considerable theoretical research in the lab has demonstrated its feasibility and prospect. However, industrialization is mandatory to realize the economic and social value of eCO2RR. For industrial application of eCO2RR, more criteria have been proposed for eCO2RR research, including high current density (above 200 mA cm−2), high product selectivity (above 90%), and long‐term stability. To fulfill these criteria, the eCO2RR system needs to be systematically designed and optimized. In this review, recent research on eCO2RR for industrial applications is summarized. The review starts with focus on potential industrial catalysts in eCO2RR. Next, potential industrial products are proposed in eCO2RR. These products, including carbon monoxide, formic acid, ethylene, and ethanol, all have high market demand, and have shown high current density and product selectivity in theoretical research. Notably, the innovative components and strategy for industrializing the eCO2RR system are also highlighted here, including flow cells, seawater electrolytes, solid electrolytes, and a two‐step method. Finally, some instructions and possible future avenues are presented for the prospects of future industrial application of eCO2RR.

High Performance of Simple Organic Phosphorescence Host-Guest Materials and their Application in Time-Resolved Bioimaging.

The study of purely organic room-temperature phosphorescence (RTP) has drawn increasing attention because of its considerable theoretical research and practical application value. Currently, organic RTP materials with both high efficiency (ΦP > 20%) and a long lifetime (τP > 10 s) in air are still scarce due to the lack of related design guidance. Here, a new strategy to increase the phosphorescence performance of organic materials by integrating the RTP host and RTP guest in one doping system to form a triplet exciplex, is reported. With these materials, the high-contrast labeling of tumors in living mice and encrypted patterns in thermal printing are both successfully realized by taking advantage of both the long afterglow time (up to 25min in aqueous media) and high phosphorescence efficiency (43%).

Stable Olympicenyl Radicals and Their π-Dimers.

An olympicenyl radical, a spin 1/2 hydrocarbon radical with C2v symmetry and uneven spin distribution, remains elusive despite the considerable theoretical research interest. Herein, we report syntheses of two air-stable olympicenyl radical derivatives, OR1 and OR2, with half-life times (τ1/2) in air-saturated solution of 7 days and 34 days. The high stability was ascribed to kinetic blocking of reactive sites with high spin densities. X-ray crystallographic analysis revealed unique 20-center-2-electron head-to-tail π-dimer structures with intermolecular distances shorter than the sum of van der Waals radius of carbon. The ground state of the π-dimers was found to be singlet, with singlet-triplet energy gaps estimated to be -2.34 kcal/mol and -3.28 kcal/mol for OR1 and OR2, respectively, by variable-temperature electron spin resonance (ESR) spectroscopy. The monomeric radical species were in equilibrium with the π-dimer in solution, and the optical and electrochemical properties of the monomers and π-dimers in solution were investigated by UV-vis-NIR spectroscopy and cyclic voltammetry, revealing a concentration-dependent nature. Theoretical calculations illustrated that upon formation of a π-dimer the local aromaticity of each monomer was enhanced, and spatial ring current between the monomers was present, which resulted in an increment of aromaticity of the interior of the π-dimer.

The Theoretical Estimation of the Bioluminescent Efficiency of the Firefly via a Nonadiabatic Molecular Dynamics Simulation.

The firefly is famous for its high bioluminescent efficiency, which has attracted both scientific and public attention. The chemical origin of firefly bioluminescence is the thermolysis of the firefly dioxetanone anion (FDO(-)). Although considerable theoretical research has been conducted, and several mechanisms were proposed to elucidate the high efficiency of the chemi- and bioluminescence of FDO(-), there is a lack of direct experimental and theoretical evidence. For the first time, we performed a nonadiabatic molecular dynamics simulation on the chemiluminescent decomposition of FDO(-) under the framework of the trajectory surface hopping (TSH) method and theoretically estimated the chemiluminescent quantum yield. The TSH simulation reproduced the gradually reversible charge-transfer initiated luminescence mechanism proposed in our previous study. More importantly, the current study, for the first time, predicted the bioluminescence efficiency of the firefly from a theoretical viewpoint, and the theoretical prediction efficiency is in good agreement with experimental measurements.

Entrepreneurial signaling to attract resources: the case of franchising

AbstractWhy firms and individuals reveal information is the subject of considerable theoretical research, but little empirical work has been possible due to a lack of suitable data. In this paper we examine why entrepreneurs selling business opportunities (franchisors) reveal information regarding potential profits (termed earnings claims). Empirical analysis shows that: first, contrary to theory, only a small percentage of franchisors claim; and, second, the franchisors that do claim have lower costs or are responding to competition. In particular, the prediction of theoretical models from economics that resource providers will not transact if information is not disclosed is not supported; resource providers can and do make significant investments even when entrepreneurs refuse to disclose information. Copyright © 2009 John Wiley & Sons, Ltd.

Demography and habitat availability in territorial occupancy of two competing species

Although metapopulation dynamics have become the focus of considerable theoretical research, little attention has been paid to its role when examining the coexistence of species. When two or more species live in the same patch network, interspecific interactions may affect their dispersal, colonization and extinction rates, and it may be possible to incorporate competition affecting these parameters in metapopulation models. Here, we extend the territorial occupancy model proposed by Lande to competing species. Our model estimates an equilibrium proportion of habitat occupancy as a function of life‐history parameters, dispersal behavior, habitat suitability and interspecific interactions. Moreover, it could prove to be useful as a tool in the assessment of potential management decisions. We apply the model to the goldenAquila chrysaetosand the Bonelli's eagleHieraaetus fasciatus, two territorial raptors that coexist in the Mediterranean region, sharing food and nesting habitats. Over the last twenty years, while the golden eagle has maintained and, in some cases, increased its breeding numbers, Bonelli's eagle has suffered a marked decline, with many territories abandoned by the latter now occupied by the former. This suggests that the dynamics of these species could be influenced by interspecific competition. The model identified the relative importance of competition (stable equilibrium that allows long‐term coexistence) and predicted that, when habitat overlap is slight as in the study area, intraspecific dynamics are much more important for the persistence of each species than interspecific ones. Our results suggest that the improvement of territorial bird survival and productivity are the most urgently needed actions to be undertaken in the case of the golden eagle, while for Bonelli's eagle efforts should be focused on improving territorial and non‐territorial bird survival. As habitat conservation measures, the proportion of suitable exclusive habitat should be increased for both species.

Auctions and the Price of Art

This paper contains a review of the burgeoning research that has been designed to shed light on how the art auction system actually works and what it indicates about price formation. First, we find that in recent years returns on art assets appear to be little different from returns on other assets. In addition, some researchers have found that because of the weak correlation between art asset returns with other returns, there may be a case for the inclusion of art assets in a diversified portfolio. Second, we find evidence of several anomalies in art market pricing. The evidence clearly suggests that, contrary to the view of the art trade, masterpieces underperform the market. In addition, there is considerable evidence that there are fairly long periods in which art prices may diverge across geographic areas and even auction houses. Third, we review the public record of the criminal trial of Sotheby`s former Chairman, who was accused of price fixing, to show how the collusion with Christie`s, the other great public auction house, was actually engineered. Contrary to the way the proceeds from the settlement of the civil suit in this case were distributed, we show that buyers were almost certainly not injured by the collusion, but that sellers were. In addition, based on the public record of settlement, it appears that the plaintiffs in the civil suit were very handsomely repaid for their injury. Finally, we review the extensive research on the effects of the auction institution on price formation. There is now considerable theoretical research on strategic behavior in auctions, much of it in response to empirical findings, and we review three key findings. First, the evidence suggests that art experts provide extremely accurate predictions of market prices, but that these predictions do not optimally process the publicly available information. Second, high reserve prices, and the resulting high unsold (buy-in) rates are best explained as optimal search in the face of stochastic demand. Third, extensive research has documented that the prices of identical objects are more likely to decline than to increase when multiple units are sold, and this has led to considerable theoretical research. Subsequent empirical research has tended to document declining demand prices even when the objects are imperfect substitutes.

Fatigue crack growth at arbitrary angles to bimaterial interfaces

The fracture characteristics of monotonically loaded cracks located parallel to, in the vicinity of, and at arbitrary angles to the interface between two elastic solids have the subjects of considerable theoretical research in the literature. The present experimental work on steel-steel bimaterials clearly demonstrates that, for essentially the same elastic properties, the plastic mismatch between the constituent layers of bilayer composite can dictate whether a fatigue crack approaching the interface at various angles continues to advance through the interface or arrests prior to penetrating the interface. The former crack arrest phenomenon occurs when the fatigue crack approaches the interface from the plastically weaker material, whereas continued crack growth results when the crack approaches the interface from the plastically stronger material. The observed experimental trends are qualitatively consistent with the numerical predictions of crack-tip shielding or amplification from the interaction of the near-tip plastic zone with an interface oriented normal to the plane of the crack. When the fatigue crack is initiated parallel to the interface, it deviates from the strongly bonded interface to advance in one of the two steels. This trend appears to experimentally confirm predictions of the possible evolution of strong mode mixity ahead of interface cracks subjectedmore » to cyclic tensile loading.« less

Experimental observation of self-replicating spots in a reaction–diffusion system

IN his classic 1952 paper, Turing1 suggested a possible connection between patterns in biological systems and patterns that could form spontaneously in chemical reaction–diffusion systems. Turing's analysis stimulated considerable theoretical research on mathematical models of pattern formation, but Turing-type patterns were not observed in controlled laboratory experiments until 19902,3. Subsequently there has been a renewed interest in chemical pattern formation and in the relationship of chemical patterns to the remarkably similar patterns observed in diverse physical and biological systems4. Numerical simulations of a simple model chemical system have recently revealed spot patterns that undergo a continuous process of 'birth' through replication and 'death' through overcrowding5. Here we report the observation of a similar phenomenon in laboratory experiments on the ferrocyanide–iodate–sulphite reaction. Repeated growth and replication can be observed for a wide range of experimental parameters, and can be reproduced by a simple two-species model, suggesting that replicating spots may occur in many reaction–diffusion systems.

Applications of Mathematical Control Theory to Finance: Modeling Simple Dynamic Cash Balance Problems

In this paper we have dealt with several time dependent cash balance models and have solved them using some form of a control theory maximum principle. The kinds of solutions we obtained were intuitively satisfying from a financial analysis point of view. The main effort for the future will be to extend these very simple models to much more realistic and complicated ones. But to do this will require considerable theoretical research in the area of both deterministic and stochastic control theory. We hope that we have demonstrated the usefulness of these theories in the area of finance and we expect many similar applications to be made in the future.