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Referring expression comprehension (REC) is a challenging task that involves locating a particular object in an image based on a natural language query. Despite REC showing potential for identifying objects beyond a fixed set of predefined categories, existing models display limited accuracy when confronted with categories not seen during training. To overcome this limitation, in this work, we introduce a new setting called Open-Category Referring Expression Comprehension that focuses more on model generalization capabilities on unseen categories, and present an Multi-modal Knowledge Transfer REC (MTKREC) framework to address this challenge. Specifically, to handle various novel categories, our framework initially constructs an isolated proposal embedding method that integrates pre-training knowledge from CLIP. This method isolates object proposals by cropping them, passing them to CLIP for box-level embedding, and concurrently obtaining box-level proposal embedding from Faster-RCNN. Then, inspired by ResNet, our framework proposes a Residual Self-Attention (RSA) strategy within the fusion module to maximize the utilization of information from the isolated proposal embedding method. To further bolster the model's capabilities, we transfer knowledge from UNITER by reusing its parameters during the multi-modal fusion process, and explore knowledge distillation techniques to accelerate the model's performance. We also construct new datasets sub-sampled from RefCOCO, RefCOCO+, and RefCOCOg datasets, that enable evaluation for our model. Extensive experiments on new datasets demonstrate the effectiveness of our framework. [ABSTRACT FROM AUTHOR]

In NH3 capture technologies, the desorption process is usually driven by high temperature and low pressure (such as 150–200 °C under vacuum), which accounts for intensive energy consumption and CO2 emission. Developing light responsive adsorbent is promising in this regard but remains a great challenge. Here, we for the first time designed and synthesized a light responsive azophenol‐containing covalent organic framework (COF), COF‐HNU38, to address this challenge. We found that at 25 °C and 1.0 bar, the cis ‐COF exhibited a NH3 uptake capacity of 7.7 mmol g−1 and a NH3/N2 selectivity of 158. In the adsorbed NH3, about 29.0 % could be removed by vis‐light irradiated cis‐trans isomerization at 25 °C, and the remaining NH3 might be released at 25 °C under vacuum. Almost no decrease in adsorption capacity was observed after eight adsorption‐desorption cycles. As such, an efficient NH3 capture and low energy release strategy was established thanks to the multiple hydrogen bond interactions (which are strong in total but weak in individuals) between NH3 and the smart COF, as well as the increased polarity and number of hydrogen bond sites after the trans‐cis isomerization. [ABSTRACT FROM AUTHOR]

In NH3 capture technologies, the desorption process is usually driven by high temperature and low pressure (such as 150–200 °C under vacuum), which accounts for intensive energy consumption and CO2 emission. Developing light responsive adsorbent is promising in this regard but remains a great challenge. Here, we for the first time designed and synthesized a light responsive azophenol‐containing covalent organic framework (COF), COF‐HNU38, to address this challenge. We found that at 25 °C and 1.0 bar, the cis ‐COF exhibited a NH3 uptake capacity of 7.7 mmol g−1 and a NH3/N2 selectivity of 158. In the adsorbed NH3, about 29.0 % could be removed by vis‐light irradiated cis‐trans isomerization at 25 °C, and the remaining NH3 might be released at 25 °C under vacuum. Almost no decrease in adsorption capacity was observed after eight adsorption‐desorption cycles. As such, an efficient NH3 capture and low energy release strategy was established thanks to the multiple hydrogen bond interactions (which are strong in total but weak in individuals) between NH3 and the smart COF, as well as the increased polarity and number of hydrogen bond sites after the trans‐cis isomerization. [ABSTRACT FROM AUTHOR]

The price of alloying element Bi is low, and it has a high solid solubility in magnesium, and with the decrease of temperature, its solid solubility decreases, and the Mg3 Bi2 phase is precipitated, which improves the mechanical properties of magnesium. Therefore, Mg-Bi alloys have good solution and aging hardening potential. The addition of Sn, Mn, Al, Ca, Zn and other elements to Mg-Bi alloy can modulate the alloy microstructure and further increase the mechanical properties and corrosion resistance of the alloy. In this paper, the research progress of Mg-Bi alloys was introduced, and on the basis of summarizing the research achievements of Mg-Bi binary alloys, the microstructure and properties of Mg-Bi-Sn alloys, Mg-Bi-Mn alloys, Mg-Bi-Al alloys, Mg-Bi-Ca alloys, and Mg-Bi-Zn alloys were systematically summarized, and the effects of alloying on the second phase, grain size, texture and dynamic recrystallization of alloys were reviewed. The effects of alloying element types, addition amounts and hot working parameters on the mechanical properties of alloys were described, and the future research is prospected. The existing problems in the study of Mg-Bi alloys were summarized, and the future research was prospected. [ABSTRACT FROM AUTHOR]

The utilization of CO2 from flue gas as a C1 feedstock for the catalytic synthesis of high-valued oxazolidinones is highly important but challenging due to the low CO2 concentration and high activation barrier for CO2. Herein, we present an efficient and stable CuI-anchored porous covalent organic framework CuI@TpBD-COF for effective catalysis of the carboxylic cyclization reaction between propargylic amines and CO2 to produce various functionalized oxazolidinone derivatives under mild conditions. The yield is up to 99% and the turnover frequency (TOF) reaches a record value of 1058 h−1, significantly surpassing almost all previously reported metal heterogeneous catalysts. Furthermore, CuI@TpBD-COF also demonstrates efficient catalytic activity when simulated flue gas is used as the source of CO2. This work provides new guidance for the design of more efficient and eco-friendly noble-metal-free catalytic materials to drive the ideal CO2 chemical fixation process. [ABSTRACT FROM AUTHOR]

• A simple integrated method on in-situ photochemical exfoliation of COF was developed. • The exfoliated COF nanosheets exhibit a high H 2 yield of 67.94 mmol g−1h−1. • With increasing cycle test number, H 2 yield was increase and COF became thinner. • The more active sites and favorable carrier separation boosted catalytic H 2 evolution. • The insertion of Eosin Y and H 2 diffusion were the driving forces for COF stripping. Covalent organic frameworks (COFs) have great potential in solar hydrogen production to alleviate environmental pollution and global energy crisis. However, to achieve high H 2 yield is still a challenge. Herein, we designed and synthesized two Fe3+-coordinated imine type COFs (Fe-COFs) for photocatalytic H 2 production from water splitting. It was surprising to find that with the progress of H 2 evolution under visible light, the bulk powders of Fe-COFs (180–250 nm) were gradually stripped into covalent organic nanosheets (Fe-CONs, 0.3–1.9 nm), which in turn efficiently catalyzed H 2 production. As such, a self-driven mechanism was established in the catalytic system, and H 2 evolution rate increased with the increase of cyclic runs until the thickness of the nanosheet no longer changes in the regeneration and reuse process of the Fe-CON photocatalysts. The optimal Fe-CON catalyst exhibited a record high H 2 evolution rate of 67.94 mmol g−1h−1 among the currently reported COFs loaded with other non-noble metals, due to the more exposed active sites, smaller charge-transfer resistance, and stronger separation ability of the photogenerated electrons and holes of Fe-CONs. This work provides the first example for the integration of self-driven photochemical exfoliation of 2D materials and their highly efficient photocatalytic hydrogen evolution. [ABSTRACT FROM AUTHOR]

A unique CuⅠ-CuⅡHHTP@Cu0 MOF film electrocatalyst with confined and stable CuⅠ (1 1 1) sites was prepared by in-situ electrochemical assembly on Cu0 (1 0 0) foil and then pre-reduction, this electrocatalyst shows an outstanding performance in CO 2 electroreduction with C2 products selectivity of 72.6%, more than 50 h of stability, and high current density of 301 mA cm−2. [Display omitted] • CuⅠ (1 1 1) sites were confined and stabilized by a unique CuⅡHHTP@Cu0 MOF film. • CuⅠ-CuⅡHHTP@Cu0 film efficiently boosts the selectivity (72.6 %) and stability (50 h) of C2 products. • The optimized microenvironment of the CuⅠ (1 1 1) sites reduces the energy barrier of *OCCOH coupling. Cu-based catalysts, especially co-sites of Cu0 and CuⅠ, are the best competitors for electrochemical CO 2 fixation to produce multi-carbon (C2 +) products. However, it is challenging to construct highly stable CuⅠ sites due to the changeability of its valence state and electronic structure in the electroreduction process, and the mechanism is also elusive. Herein, a 2D conductive CuⅡ-MOF film (CuⅡHHTP@Cu0) is prepared on Cu (1 0 0) foil by in-situ electrochemical assembly. After pre-reduction, the in-situ produced Cu 2 O clusters are confined in the cavities of the film created by the local breaking of the MOF framework to construct a unique CuⅠ-CuⅡHHTP@Cu0 catalyst, so that a novel strategy is proposed to stablize highly dispersed CuⅠ sites during electrochemical reduction, thus protecting the Cu 2 O clusters from further reduction and ensuring the coexistence of CuⅠ (1 1 1)-Cu0 (1 0 0) sites. As such, the current density of CO 2 electrochemical reduction catalyzed by this catalyst exceeds 300 mA cm−2, the duration overs 50 h, and the C2 selectivity achieves 72.6 %. In-situ spectroscopy and theoretical calculations reveal that the optimized microenvironment of the CuⅠ (1 1 1) sites reduces the energy barrier of *OCCOH coupling, and Cu0 (1 0 0) sites increase the coverage of *CO, thus boosting the production of C2 products. [ABSTRACT FROM AUTHOR]

[Display omitted] • Hybrid materials with photothermal conversion performance were prepared for low-energy desorption of NH 3. • Temperature of rGO@MOF-303(Al)-8% could be raised to about 75 °C in 10 min. • About 68% of NH 3 could be effectively desorbed from the adsorbent in 2-hour irradiation. • Excellent desorption performance of NH 3 under sunlight irradiation is attributed to the rapid temperature rise of the adsorbent. The capture, storage and release of NH 3 play a pivotal role in sustainable energy applications. However, to simultaneously achieve high adsorption capacity and low energy desorption remains a challenge. In this work, a novel class of hybrid materials with photothermal conversion performance have been developed by doping redox graphene and metal–organic framework of MOF-303(Al). It is found that the optimized rGO@MOF-303(Al)-8% exhibits high NH 3 uptake (17.0 mmol g−1) at 25.0 °C and 1.0 bar and exceptional photothermal conversion performance. Under the irradiation of simulated sunlight, its temperature can be raised to about 75 °C in 10 min. Even under direct natural sunlight irradiation, a stable equilibrium temperature of 53 °C may be achieved. Based on this excellent photothermal conversion performance, we investigated the desorption behavior of ammonia under visible light irradiation for the first time. We found that due to the breakdown of hydrogen bonds of NH 3 and N-N, N–H sites of rGO@MOF-303(Al)-8% caused by the rapid rise of temperature, approximately 68% of NH 3 could be effectively desorbed in 2-hour irradiation under ambient conditions. In addition, the optimized adsorbent demonstrated remarkable cycling stability. After undergoing 10 cycles, high adsorption capacity and efficient light-induced desorption of NH 3 were still maintained Thus, the present study provides a novel concept for high-capacity adsorption and low-energy desorption of NH 3 and other industrial gases. [ABSTRACT FROM AUTHOR]

The concerted catalysis throughout multiple elementary steps is key to impel sluggish hydrogen evolution reaction (HER). Herein, NiMo/Mo 2 N/NC(500-R) array is constructed by embedding densely packed NiMo/Mo 2 N heterojunctions into nanorod skeleton of nitrogen-rich derived carbons (NC), then followed by electrochemical surface reconstruction. The great electrochemical surface area of resultant electrocatalyst implies fully-exposed concerted diatomic-ensembles. The ensemble effect of unique heteronanojunction induces charge polarizations between Mo and Ni species, gives pseudocapacitance comparable to supercapacitors, and pumps mass transfers to refresh entire HER process. The exceptional activity is demonstrated by ultra-low overpotentials of 5.8 and 200.6 mV respectively at 10 and 1000 mA cm−2, the impressive durability is indicated by lasting alkaline HER for 1000 h at 1 A cm−2. Moreover, the performances in water-alkali electrolyzer outperform most reported catalysts. This work presents valuable insights into concerted catalysis and designing efficient and durable electrocatalysts by ensemble effect from different metal heterojunctions for commercial applications. [Display omitted] • Well-separated heteronanojunctions impart the enhanced intrinsic activity to array. • Ensemble effect refreshes the concerted diatomic sites by charge polarizations. • Electrocatalyst delivers ultra-low overpotentials in alkaline hydrogen evolution. • Striking durability makes electrocatalyst commercializable in hydrogen production. • In-depth insights offer guidance to design efficient and durable electrocatalysts. [ABSTRACT FROM AUTHOR]

Pd/C-[BMIm][BF 4 ] catalyst displayed high activity for acceptorless dehydrogenation of biomass-derived alcohols to produce aromatic ketones under mild conditions without any acid/base additives, and this catalyst could be recovered and reused for 5 runs without obvious activity loss. This work provides a potential approach for the effective utilization of renewable biomass resources to produce aromatic compounds and clean H 2. [Display omitted] • The combination of Pd/C with specific ionic liquid of 1-butyl-3-methylimidazolium tetrafluoroborate ([BMIm][BF 4 ]) displayed high activity for the dehydrogenation of aromatic alcohols to produce aromatic ketones. • The Pd/C-[BMIm][BF 4 ] pair promoted the dehydrogenation of aromatic alcohols and inhabited the hydrogenation of aromatic alcohols. • The catalyst could be recycled for 5 runs without obvious loss of activity. • Pd/C could be anchored and stabilized by the IL through interacting with [BMIm]+ cation, and both the [BMIm]+ cation and the [BF 4 ]- anion play vital roles in activating hydroxyl-H and hydroxyl α-H of the aromatic alcohol. Acceptorless dehydrogenation of alcohols is a promising pathway for biomass resource utilization and hydrogen supply, but still lacking for simple and effective catalysts. Herein, we report a metal-ionic liquids (ILs) catalyst for synergistical catalytic dehydrogenation of aromatic alcohols to aromatic ketones under mild conditions without any acid/base additives. It is found that the combination of Pd/C with 1-butyl-3-methylimidazolium tetrafluoroborate ([BMIm][BF 4 ]) displays high activity for the dehydrogenation of biomass-derived alcohols including 1-phenyl-1-ethanol, 1-phenyl-1-propanol and 1-(4-methoxyphenyl)ethanol. Mechanistic studies reveal that the Pd/C can be anchored and stabilized by the IL via interacting with [BMIm]+ cation, and the [BF 4 ]- anion plays vital role in the activation of hydroxyl-H and α-H protons via hydrogen bonding interactions. These interactions create an effective microenvironmental for Pd/C catalyzing the cleavage of the hydroxyl-H and α-C H bonds of α-hydroxyl aromatic alcohols to generate aromatic ketones and H 2. Moreover, the Pd/C-[BMIm][BF 4 ] catalyst could be recovered and reused for 5 runs without obvious activity loss. This strategy provides more evidences for the synergetic catalysis of metal and ionic liquids and exhibits potential application prospects for hydrogen supply from renewable biomass-derived alcohols. [ABSTRACT FROM AUTHOR]