Numerous efficient synthetic methods for enantioselective indole functionalizations have emerged in recent years. This review summarizes the major achievements in the transition-metal-catalyzed ...enantioselective indole functionalization reactions since 2010 and focuses on C-C bond formation processes, including alkylations, arylations, cycloaddition reactions, and other reactions. It intends to give a compendious overview of the significant progress achieved in this area.
Computation-in-memory (CIM) is a promising candidate to improve the energy efficiency of multiply-and-accumulate (MAC) operations of artificial intelligence (AI) chips. This work presents an static ...random access memory (SRAM) CIM unit-macro using: 1) compact-rule compatible twin-8T (T8T) cells for weighted CIM MAC operations to reduce area overhead and vulnerability to process variation; 2) an even-odd dual-channel (EODC) input mapping scheme to extend input bandwidth; 3) a two's complement weight mapping (C2WM) scheme to enable MAC operations using positive and negative weights within a cell array in order to reduce area overhead and computational latency; and 4) a configurable global-local reference voltage generation (CGLRVG) scheme for kernels of various sizes and bit precision. A 64 × 60 b T8T unit-macro with 1-, 2-, 4-b inputs, 1-, 2-, 5-b weights, and up to 7-b MAC-value (MACV) outputs was fabricated as a test chip using a foundry 55-nm process. The proposed SRAM-CIM unit-macro achieved access times of 5 ns and energy efficiency of 37.5-45.36 TOPS/W under 5-b MACV output.
Improving the accuracy of estimates of forest carbon exchange is a central priority for understanding ecosystem response to increased atmospheric CO2 levels and improving carbon cycle modelling. ...However, the spatially continuous parameterization of photosynthetic capacity (Vcmax) at global scales and appropriate temporal intervals within terrestrial biosphere models (TBMs) remains unresolved. This research investigates the use of biochemical parameters for modelling leaf photosynthetic capacity within a deciduous forest. Particular attention is given to the impacts of seasonality on both leaf biophysical variables and physiological processes, and their interdependent relationships. Four deciduous tree species were sampled across three growing seasons (2013–2015), approximately every 10 days for leaf chlorophyll content (ChlLeaf) and canopy structure. Leaf nitrogen (NArea) was also measured during 2014. Leaf photosynthesis was measured during 2014–2015 using a Li‐6400 gas‐exchange system, with A‐Ci curves to model Vcmax. Results showed that seasonality and variations between species resulted in weak relationships between Vcmax normalized to 25°C (Vcmax25) and NArea (R2 = 0.62, P < 0.001), whereas ChlLeaf demonstrated a much stronger correlation with Vcmax25 (R2 = 0.78, P < 0.001). The relationship between ChlLeaf and NArea was also weak (R2 = 0.47, P < 0.001), possibly due to the dynamic partitioning of nitrogen, between and within photosynthetic and nonphotosynthetic fractions. The spatial and temporal variability of Vcmax25 was mapped using Landsat TM/ETM satellite data across the forest site, using physical models to derive ChlLeaf. TBMs largely treat photosynthetic parameters as either fixed constants or varying according to leaf nitrogen content. This research challenges assumptions that simple NArea–Vcmax25 relationships can reliably be used to constrain photosynthetic capacity in TBMs, even within the same plant functional type. It is suggested that ChlLeaf provides a more accurate, direct proxy for Vcmax25 and is also more easily retrievable from satellite data. These results have important implications for carbon modelling within deciduous ecosystems.
Improving modelled estimates of forest carbon exchange requires accurate parameterization of photosynthetic capacity (Vcmax) within terrestrial biosphere models (TBMs). This research investigates leaf biochemical variables for modelling photosynthetic parameters within a deciduous forest. Seasonality and interspecies variability resulted in weak correlations between Vcmax and leaf nitrogen; challenging assumptions that simple nitrogen–Vcmax25 relationships can reliably constrain photosynthetic capacity in TBMs. Conversely, leaf chlorophyll (ChlLeaf) accounted for 76% of Vcmax25 variability, suggesting that ChlLeaf provides a more accurate and direct proxy for Vcmax.
Despite much progress has been made in recent years, the estimation of terrestrial gross primary productivity (GPP) remains highly uncertain. Recent studies have demonstrated the usefulness of ...sun-induced chlorophyll fluorescence (SIF) from plants for estimating GPP. In this study, the relationships of GPP to SIF and Photochemical Reflectance Index (PRI) under different environmental conditions are established using carbon flux data at 61 sites distributed globally and coincident SIF data from OCO-2 and PRI data from MODIS. We analyzed OCO-2 SIF data at both 757 nm and 771 nm against instantaneous and daily GPP values derived from the tower flux data. Our results for these four cases are similar, and those with SIF at 757 nm and daily GPP show that: (1) a significant relationship is found between GPP and observed SIF (SIFobs) for all vegetation types (R2 = 0.53, RMSE = 4.28 μmol m−2 s−1p < .001); (2) NIRv, a product of the normalized difference vegetation index (NDVI) and near-infrared reflectance, can be used as an approximation of the canopy-escaping probability of emitted SIF to convert observed SIF at one angle to the hemispherical SIF emission that is better correlated to GPP. The relationship between GPP and SIFobs/NIRv was considerably improved from that between GPP and SIFobs (R2 = 0.67, RMSE = 3.39 μmol m−2 s−1, p < .001); (3) The remaining scatter in the relationship between GPP and SIFobs/NIRv is significantly negatively correlated to PRI (R2 = 0.28–0.34, p < .001), and PRI can be used to improve the relationship between GPP and SIFobs/NIRv, (R2 = 0.73, RMSE = 3.04 μmol m−2 s−1, p < .001); and (4) After the use of PRI in the regression, the variability of the slope of GPP against SIF among different plant functional types is greatly reduced from 33% to 19%. As PRI is an indicator of the non-photochemical quenching (NPQ), a pathway that is in parallel of photochemical quenching and chlorophyll fluorescence, these improvements suggest that the information of NPQ from PRI can be used in addition to SIF for better GPP estimation.
•GPP from 61 tower flux sites is well correlated with coincident SIF from OCO-2.•This correlation is significantly improved when SIF is corrected with NIRv.•The correlation is further improved using PRI as an indicator of NPQ.•The slope of SIF against GPP varies much less among cover types when PRI is used.
Relative to electron donors for bulk heterojunction organic solar cells (OSCs), electron acceptors that absorb strongly in the visible and even near‐infrared region are less well developed, which ...hinders the further development of OSCs. Fullerenes as traditional electron acceptors have relatively weak visible absorption and limited electronic tunability, which constrains the optical and electronic properties required of the donor. Here, high‐performance fullerene‐free OSCs based on a combination of a medium‐bandgap polymer donor (FTAZ) and a narrow‐bandgap nonfullerene acceptor (IDIC), which exhibit complementary absorption, matched energy levels, and blend with pure phases on the exciton diffusion length scale, are reported. The single‐junction OSCs based on the FTAZ:IDIC blend exhibit power conversion efficiencies up to 12.5% with a certified value of 12.14%. Transient absorption spectroscopy reveals that exciting either the donor or the acceptor component efficiently generates mobile charges, which do not suffer from recombination to triplet states. Balancing photocurrent generation between the donor and nonfullerene acceptor removes undesirable constraints on the donor imposed by fullerene derivatives, opening a new avenue toward even higher efficiency for OSCs.
High‐performance fullerene‐free single‐junction organic solar cells with power conversion efficiencies up to 12.5% are reported. Transient absorption spectroscopy reveals that exciting either the donor or acceptor component efficiently generates mobile charges, which do not suffer from recombination to triplet states.
•An offline retailer and an online retailer face strategic customers and compete.•Strategic customers free ride: experience the product offline and buy online.•Three pricing strategies are proposed ...and discussed for offline retailer.•When the offline retailer should implement a price matching strategy is identified.•Offline retailer's profit may increase with portion of strategic customers.
In this paper, we develop a duopoly game using the Hotelling model, in which customers are uniformly distributed along the Hotelling line, and a brick-and-mortar retailer who sits on the left end of the line competes with an online retailer. The brick-and-mortar retailer is the Stackelberg leader facing strategic customers and the online retailer is the follower. Strategic customers may free ride on the BM retailer's service by first visiting the BM retailer and experiencing the product, but then switching to the online retailer to buy the product, if the retail price at the online retailer is sufficiently low. The conditions under which the BM retailer should or should not implement a price matching strategy are identified. If the cost of shopping online is high, the BM retailer can ignore the strategic customers’ behavior; there is no incentive to switch to buy the product online. When the customer's shopping cost is moderate, the BM retailer should implement a price matching strategy to prevent strategic customers from switching to the online retailer. When the cost of shopping online is low, the BM retailer should not try to match the price of the online retailer. We also show that the BM retailer's profit may increase, while the online retailer's profit may decrease, with the portion of strategic customers in the market, when the BM retailer implements a price matching strategy. When the fraction of strategic customers is sufficiently high, the BM retailer will not implement price matching strategy.
This article argues that positive US-China relations enabled China in 2004 to diversify its strategy toward Haiti, a staunch supporter of Taiwan, by contributing its first-ever Formed Police Unit ...(FPU) to the United Nations Stabilization Mission in Haiti (MINUSTAH). The organizational readiness of the China Peacekeeping Police Training Center (CPPTC) also played a large role in shaping this development. With the contribution of its FPUs, China intended to influence Haiti and reset bilateral relations. However, the limited training capacity of CPPTC meant that China could only contribute one FPU at a time—even though contributing more FPUs would have strengthened its influence on Haiti even more. When US-China relations turned negative and Zhou Yongkang, the chief patron of the Chinese police, lost power in 2012, China terminated its participation.
In large wireless rechargeable sensor networks (WRSNs), the limited battery capacity of sensor nodes and finite network lifetime are commonly considered as performance bottlenecks. Previous works ...have employed wireless mobile vehicles (vehicles) to charge sensor nodes (nodes), but they face limitations in terms of low speed and offroad terrain. The rapid development of wireless charging drones (drones) brings a new perspective on charging nodes; nevertheless, their use is limited by small capacity batteries and cannot cover large regions alone. Most existing works consider the charging of nodes only with vehicles or drones. However, these solutions may not be robust enough, as some nodes’ energy will have run out before vehicles’ or drones’ arrival. Considering the merits and demerits of vehicles and drones comprehensively, we propose a novel WRSN model whose charging system integrates one vehicle, multiple drones and one base station together. Moreover, a charging strategy named long-distance first matching (LDFM) algorithm to schedule the vehicle and multiple drones collaboratively is proposed. In the proposed scheme, drones that are carried by the vehicle start from the base station. According to distance and deadline of nodes with charging requests, LDFM prioritizes nodes with the longest matching distance for allocation to drones. As a result, the proposed scheme aims to minimize the moving distance of charging scheduling of the WCV on premise of satisfying charging requests with the cooperation of WCVs and drones. Our proposed scheme is thus designed to maximize the efficiency of drone usage and shares the charging burden of the vehicle, which makes WRSNs work well in large and complex terrain regions, such as a hill, natural disaster areas or war zones. Simulation results confirm that our proposed scheme outperforms hybrid scheme in previous work with respect to total number of charging nodes and network energy consumption. Especially with heavy traffic load, the proposed scheme can charge more than 10% additional nodes compared to the hybrid. Moreover, the proposed scheme achieves a reduction of over 50% in the moving distance compared to the hybrid.
Near infrared light photodiodes have been attracting increasing research interest due to their wide application in various fields. In this study, the fabrication of a new n‐type GaAs nanocone ...(GaAsNCs) array/monolayer graphene (MLG) Schottky junction is reported for NIR light detection. The NIR photodetector (NIRPD) shows obvious rectifying behavior with a turn‐on voltage of 0.6 V. Further device analysis reveals that the photovoltaic NIRPDs are highly sensitive to 850 nm light illumination, with a fast response speed and good spectral selectivity at zero bias voltage. It is also revealed that the NIRPD is capable of monitoring high‐switching frequency optical signals (∼2000 Hz) with a high relative balance. Theoretical simulations based on finite difference time domain (FDTD) analysis finds that the high device performance is partially associated with the optical property, which can trap most incident photons in an efficient way. It is expected that such a self‐driven NIRPD will have potential application in future optoelectronic devices.
A new Schottky junction near‐infrared light photodetector is fabricated by coating a GaAs nanocone array with a monolayer graphene film, which shows high sensitivity to near‐infrared light irradiation, with good reproducibility, excellent selectivity, and rapid response speed.
Chemoresistance and migration represent major obstacles in the therapy of non‐small‐cell lung cancer (NSCLC), which accounts for approximately 85% of lung cancer patients in clinic. In the present ...study, we report that the compound C1632 is preferentially distributed in the lung after oral administration in vivo with high bioavailability and limited inhibitory effects on CYP450 isoenzymes. We found that C1632 could simultaneously inhibit the expression of LIN28 and block FGFR1 signalling transduction in NSCLC A549 and A549R cells, resulting in significant decreases in the phosphorylation of focal adhesion kinase and the expression of matrix metalloproteinase‐9. Consequently, C1632 effectively inhibited the migration and invasion of A549 and A549R cells. Meanwhile, C1632 significantly suppressed the cell viability and the colony formation of A549 and A549R cells by inhibiting DNA replication and inducing G0/G1 cell cycle arrest. Interestingly, compared with A549 cells, C1632 possesses the same or even better anti‐migration and anti‐proliferation effects on A549R cells, regardless of drug resistance. In addition, C1632 also displayed the capacity to inhibit the growth of A549R xenograft tumours in mice. Altogether, these findings reveal the potential of C1632 as a promising anti‐NSCLC agent, especially for chemotherapy‐resistant NSCLC treatment.
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