Herein, the first acceptorless dehydrogenation of tetrahydroquinolines (THQs), indolines, and other related N‐heterocycles, by merging visible‐light photoredox catalysis and cobalt catalysis at ...ambient temperature, is described. The potential applications to organic transformations and hydrogen‐storage materials are demonstrated. Primary mechanistic investigations indicate that the catalytic cycle occurs predominantly by an oxidative quenching pathway.
Cobalt and blue: The titled method is utilized for the reversible dehydrogenation‐hydrogenation protocol at ambient temperature under mild reaction conditions. Primary mechanistic investigations indicate that the catalytic cycle relies predominantly on an oxidative quenching pathway.
Morella rubra, red bayberry, is an economically important fruit tree in south China. Here, we assembled the first high‐quality genome for both a female and a male individual of red bayberry. The ...genome size was 313‐Mb, and 90% sequences were assembled into eight pseudo chromosome molecules, with 32 493 predicted genes. By whole‐genome comparison between the female and male and association analysis with sequences of bulked and individual DNA samples from female and male, a 59‐Kb region determining female was identified and located on distal end of pseudochromosome 8, which contains abundant transposable element and seven putative genes, four of them are related to sex floral development. This 59‐Kb female‐specific region was likely to be derived from duplication and rearrangement of paralogous genes and retained non‐recombinant in the female‐specific region. Sex‐specific molecular markers developed from candidate genes co‐segregated with sex in a genetically diverse female and male germplasm. We propose sex determination follow the ZW model of female heterogamety. The genome sequence of red bayberry provides a valuable resource for plant sex chromosome evolution and also provides important insights for molecular biology, genetics and modern breeding in Myricaceae family.
The asymmetric synthesis of alkynyl and monofluoroalkenyl isoindolinones from N‐methoxy benzamides and α,α‐difluoromethylene alkynes is enabled by C−H activation with a chiral CpRhIII catalyst. ...Remarkably, product formation is solvent‐dependent; alkynyl isoindolinones are afforded in MeOH (up to 86 % yield, 99.6 % ee) whereas monofluoroalkenyl isoindolinones are generated in iPrCN (up to 98:2 Z/E, 93 % yield, 86 % ee). Mechanistic studies revealed chiral allene and E‐configured alkenyl rhodium species as reaction intermediates. The latter is transformed into the corresponding Z‐configured monofluoroalkene upon protonation in the iPrCN system and into an alkyne by an unusual anti β‐F elimination in the MeOH system. Notably, kinetic resolution processes occur in this reaction. Despite the moderate enantiocontrol for the formation of the chiral allene, the Z‐monofluoroalkenyl isoindolinones and alkynyl isoindolinones were obtained in good enantiopurities by one or two sequential kinetic resolution processes.
A matter of solvent: Alkynyl and monofluoroalkenyl isoindolinones were generated with good enantioselectivities from N‐methoxy benzamides and α,α‐difluoromethylene alkynes by C−H activation with a chiral CpRhIII catalyst. Remarkably, the product formation is solvent‐dependent; whereas alkynyl isoindolinones are formed in methanol, monofluoroalkenyl isoindolinones are generated in isobutyronitrile.
Conspectus The development of DNA nanotechnology, especially the advent of DNA origami, has made DNA ideally suited to construct nanostructures with unprecedented complexity and arbitrariness. As a ...fully addressable platform, DNA origami can be used to organize discrete entities in space through DNA hybridization with nanometer accuracy. Among a variety of functionalized particles, metal nanoparticles such as gold nanoparticles (AuNPs) feature an important pathway to endow DNA-origami-assembled nanostructures with tailored optical functionalities. When metal particles are placed in close proximity, their particle plasmons, i.e., collective oscillations of conduction electrons, can be coupled together, giving rise to a wealth of interesting optical phenomena. Nevertheless, characterization methods that can read out the optical responses from plasmonic nanostructures composed of small metal particles, and especially can optically distinguish in situ their minute conformation changes, are very few. Circular dichroism (CD) spectroscopy has proven to be a successful means to overcome these challenges because of its high sensitivity in discrimination of three-dimensional conformation changes. In this Account, we discuss a variety of static and dynamic chiral plasmonic nanostructures enabled by DNA nanotechnology. In the category of static plasmonic systems, we first show chiral plasmonic nanostructures based on spherical AuNPs, including plasmonic helices, toroids, and tetramers. To enhance the CD responses, anisotropic gold nanorods with larger extinction coefficients are utilized to create chiral plasmonic crosses and helical superstructures. Next, we highlight the inevitable evolution from static to dynamic plasmonic systems along with the fast development of this interdisciplinary field. Several dynamic plasmonic systems are reviewed according to their working mechanisms. We first elucidate a reconfigurable plasmonic cross structure that can execute DNA-regulated conformational changes on the nanoscale. Hosted by a reconfigurable DNA origami template, the plasmonic cross can be switched between a chiral locked state and an achiral relaxed state through toehold-mediated strand displacement reactions. This reconfigurable nanostructure can also be modified in response to light stimuli, leading to a noninvasive, waste-free, and all-optically controlled system. Taking one step further, we show that selective manipulations of individual structural species coexisting in one ensemble can be achieved using pH tuning of reconfigurable plasmonic nanostructures in a programmable manner. Finally, we describe an alternative to achieving dynamic plasmonic systems by driving AuNPs directly on origami. Such plasmonic walkers, inspired by the biological molecular motors in living cells, can generate dynamic CD responses when carrying out directional, progressive, and reverse nanoscale walking on DNA origami. We envision that the combination of DNA nanotechnology and plasmonics will open an avenue toward a new generation of functional plasmonic systems with tailored optical properties and useful applications, including polarization conversion devices, biomolecular sensing, surface-enhanced Raman and fluorescence spectroscopy, and diffraction-limited optics.
Post‐synthetic modification (PSM) is an effective approach for the tailored functionalization of metal‐organic architectures, but its generalizability remains challenging. Herein we report a general ...covalent PSM strategy to functionalize PdnL2n metal‐organic cages (MOCs, n=2, 12) through an efficient Diels–Alder cycloaddition between peripheral anthracene substituents and various functional motifs bearing a maleimide group. As expected, the solubility of functionalized Pd12L24 in common solvents can be greatly improved. Interestingly, concentration‐dependent circular dichroism and aggregation‐induced emission are achieved with chiral binaphthol (BINOL)‐ and tetraphenylethylene‐modified Pd12L24, respectively. Furthermore, Pd12L24 can be introduced with two different functional groups (e.g., chiral BINOL and achiral pyrene) through a step‐by‐step PSM route to obtain chirality‐induced circularly polarized luminescence. Moreover, similar results are readily observed with a smaller Pd2L4 system.
Two PdnL2n (n=2, 12) type metal‐organic cages (MOCs) decorated with anthracene groups have been successfully functionalized by a covalent post‐synthetic modification (PSM) approach. This has led to the modified MOCs having new functions compared to the parent MOCs (e.g., concentration‐dependent chirality, aggregation‐induced emission, and chirality‐induced circularly polarized luminescence).
The landslide displacement in the Three Gorges Reservoir, China, experiences step-like deformation that is influenced by rainfall and the periodic scheduling of the reservoir. In view of the ...step-like characteristic, the Particle Swarm Optimization and Support Vector Machine (PSO–SVM) coupling model based on the response of the induced factors was proposed to predict the landslide displacement. The moving average method was adopted to divide the total displacement into trend term and periodic term. The trend displacement was controlled by the geological conditions and predicted by polynomial function, while the periodic displacement was under the combined control of the triggers and the evolution state of the landslide. Therefore, the PSO–SVM model, based on the factors of the precipitation, the variation range of the reservoir and the displacements of the prior-periods, was proposed to predict the periodic displacement. The typical step-like landslide in the Three Gorges Reservoir, which is known as the Bazimen landslide, was taken as a case study to verify the prediction results. The values of the root mean square error and the mean absolute percentage error were 13.28 and 25.95, respectively. The results showed that rainfall and reservoir water level were the dominant factors for the step-like landslide deformation. The evolution state of the landslide was also significant in reflecting the response relationship between the displacement and inducing factors. In conclusion, the proposed PSO–SVM model can better represent the response relationship between the factors and the periodic displacement, which made the predicted values of the total displacement fit with the measured values greatly.
•The deformation and failure mechanism of the Bazimen landslide are analyzed.•The relationship of landslide periodic displacement and the controlling factors of landslide deformation are analyzed.•Particle Swarm Optimization and Support Vector Machine are integrated and applied in landslide displacement prediction.•A landslide displacement prediction model is proposed in relation to controlling factors.
IMPORTANCE:It is important to understand the magnitude and distribution of the economic burden of prescription opioid overdose, abuse, and dependence to inform clinical practice, research, and other ...decision makers. Decision makers choosing approaches to address this epidemic need cost information to evaluate the cost effectiveness of their choices.
OBJECTIVE:To estimate the economic burden of prescription opioid overdose, abuse, and dependence from a societal perspective.
DESIGN, SETTING, AND PARTICIPANTS:Incidence of fatal prescription opioid overdose from the National Vital Statistics System, prevalence of abuse and dependence from the National Survey of Drug Use and Health. Fatal data are for the US population, nonfatal data are a nationally representative sample of the US civilian noninstitutionalized population ages 12 and older. Cost data are from various sources including health care claims data from the Truven Health MarketScan Research Databases, and cost of fatal cases from the WISQARS (Web-based Injury Statistics Query and Reporting System) cost module. Criminal justice costs were derived from the Justice Expenditure and Employment Extracts published by the Department of Justice. Estimates of lost productivity were based on a previously published study.
EXPOSURE:Calendar year 2013.
MAIN OUTCOMES AND MEASURES:Monetized burden of fatal overdose and abuse and dependence of prescription opioids.
RESULTS:The total economic burden is estimated to be $78.5 billion. Over one third of this amount is due to increased health care and substance abuse treatment costs ($28.9 billion). Approximately one quarter of the cost is borne by the public sector in health care, substance abuse treatment, and criminal justice costs.
CONCLUSIONS AND RELEVANCE:These estimates can assist decision makers in understanding the magnitude of adverse health outcomes associated with prescription opioid use such as overdose, abuse, and dependence.
This paper examines the impact of a carbon trading pilot policy on the low-carbon international competitiveness of an industry to test whether creating a carbon market causes the Porter effect. Using ...a sample of 33 industries in 30 provinces in China from 2009 to 2016 with a difference-in-difference-in-difference model (DDD) and a series of robustness tests, we find evidence of a significant positive influence of a carbon trading pilot policy on the low-carbon international competitiveness of industries covered by the pilot programs. Research on its influencing mechanism reveals that a carbon trading pilot policy promotes the low-carbon international competitiveness of industries by driving low-carbon technological progress. Furthermore, a heterogeneity analysis of industry characteristics and carbon allowance allocation methods in different pilots indicates that the impact of a carbon trading pilot policy on industry low-carbon international competitiveness is reflected mainly in industries with low-carbon emissions, high state-owned capital, and high export intensity. Compared with the grandfather method and the historical intensity method, the low-carbon international competitiveness of an industry is significantly increased when the benchmarking method is used. The results of this paper offer important insights for improving the policy design of a nationwide carbon market, as well as a reference point for other countries and regions, especially developing countries, in establishing a carbon trading market.
•A water retention model was developed for isotropic and anisotropic soils.•Stronger anisotropy makes soil pores more elongated and thus higher retention ability.•The model capability is well ...verified using experimental data.
Water retention curve (WRC) is an important parameter for unsaturated soils. It is greatly affected by the anisotropy of pore structure, as supported by experimental results in the literature. So far, however, the mechanism and theoretical modelling of anisotropy effects have not been investigated. These two issues were explored in this study based on two-dimensional analysis of soil pores, while were approximated as a series of ellipses for simplicity. According to experimental results in the literature, the pores of anisotropic specimen are more elongated than those of isotropic specimen on average. The elongated pore has a higher water retention ability than the round pore when they have the same area. As a consequence, the water retention ability of anisotropic specimen is higher than that of isotropic specimen. On the basis of this mechanism, a new WRC model was proposed for isotropic and anisotropic soils . To verify the new model, it was applied to simulate the WRCs of three soils with isotropic and anisotropic pore structures. Measured and calculated results were well matched with the coefficient of determination (R2) in the range of 0.89 to 0.99 and the root-mean-square error (RMSE) ranging from 0.009 to 0.073. It is convincingly demonstrated that the new model is able to capture the influence of anisotropy on WRC.
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