Since pioneering work done in the late 1990s, synthesis of functional hollow materials has experienced a rapid growth over the past two decades while their applications have been proven to be ...advantageous across many technological fields. In the field of heterogeneous catalysis, the development of micro‐ and nanoscale hollow materials as catalytic devices has also yielded promising results, because of their higher activity, stability, and selectivity. Herein, the architecture and preparation of these catalysts with tailorable composition and morphology are reviewed. First, synthesis of hollow materials is introduced according to the classification of template mediated, template free, and combined approaches. Second, different architectural designs of hollow catalytic devices, such as those without functionalization, with active components supported onto hollow materials, with active components incorporated within porous shells, and with active components confined within interior cavities, are evaluated respectively. The observed catalytic performances of this new class of catalysts are correlated to structural merits of individual configuration. Examples that demonstrate synthetic approaches and architected configurations are provided. Lastly, possible future directions are proposed to advance this type of hollow catalytic devices on the basis of our personal perspectives.
Hollow materials have been extensively investigated over the past two decades. Among them, catalytic hollow materials can be singled out as a unique class of advanced functional materials. These tailor‐made nanocomposites should be viewed as hollow catalytic devices because they exhibit multiple functionalities that conventional catalysts do not possess.
Previous studies are not unanimous on the effect of financial development on innovation. Digital inclusive finance is one mode of financial development, so its impact on urban innovation needs to be ...further tested. To develop digital inclusive finance, China implemented the Plan for Promoting the Development of Inclusive Finance (2016–2020) and the G20 High‐Level Principles on Digital Inclusive Finance in 2016. We take the implementation of the Plan and Principles as a quasi‐natural experiment and use the difference‐in‐difference model to estimate the pure effect of digital inclusive finance on urban innovation. The results show that implementing the Plan and Principles can increase the number of urban patents by 5.3%, indicating that digital inclusive finance has a positive effect on urban innovation. In addition, we find that digital inclusive finance can promote urban innovation by improving the allocation of credit resources, consumption, and industrial upgrading.
ab initio
calculations of dielectronic recombination rate coefficient of
W
37
+
forming
W
36
+
and electron-impact ionization cross section of
W
36
+
have been performed. Energy levels, radiative ...transition probabilities, autoionization rates, electron-impact excitation and ionization cross sections are calculated using the flexible atomic code (FAC). Good agreement between the present level-to-level distorted wave treatment and previous ADAS data is found for the dielectronic recombination rate coefficients of
W
37
+
. Electron-impact direct ionization and excitation-autoionization contributions to the total single-ionization cross sections were calculated employing a level-to-level distorted-wave approximation. The calculation result shows that the total ionization cross section will be underestimated by 50% near ionization threshold to
∼
8% at higher energy without include the contribution from excitation-autoionization process.
Graphical abstract
Synergistic catalysis is gaining increasing attention due to its advantages over traditional catalytic methodologies, such as improved catalytic activity, broader substrate scope, increased ...selectivity and lower cost. Methodologies involving the synergistic combination of metal catalysts and organocatalysts have been intensively studied. Given the clear benefits of bimetallic catalyst systems consisting of two distinct metal catalysts, cooperative bimetallic catalysis has proved to be successful for a number of difficult asymmetric transformations. This review highlights the recent advances in bimetallic systems for catalytic asymmetric allylic substitution reactions. Strategies using a chiral metal catalyst and the cooperative effect of a second achiral metal catalyst for asymmetric transformations are discussed. Additionally, several challenging asymmetric reactions realized by employing two different chiral metal catalysts in a synergistic manner are also covered.
Strategies using a chiral metal catalyst and the cooperative effect of a second achiral or chiral metal catalyst for asymmetric allylic substitution reactions are discussed.
An efficient nickel‐catalyzed asymmetric hydrogenation of N‐tBu‐sulfonyl imines was developed with excellent yields and enantioselectivities using (R,R)‐QuinoxP* as a chiral ligand. The use of a much ...lower catalyst loading (0.0095 mol %, S/C=10500) represents the highest catalytic activity for the Ni‐catalyzed asymmetric hydrogenations reported so far. Mechanistic studies suggest that a coordination equilibrium exists between the nickel salt and its complex, and that excess nickel salt promotes the formation of the active Ni‐complex, and therefore improved the efficiency of the hydrogenation. The catalytic cycle was also investigated by calculations to determine the origin of the enantioselectivity. An extensive network of numerous weak attractive interactions was found to exist between the catalyst and substrate in the transition state and may also contribute to the high catalytic activity.
The first Ni‐catalyzed asymmetric hydrogenation of N‐sulfonyl imines using H2 gas as a hydrogen source has been realized with excellent enantioselectivity. The presence of an excess of the nickel salt, with respect to the ligand, promotes the formation of the active Ni catalyst. The reaction features a wide substrate scope, low catalyst loading, and convenient removal of the protecting group.
Core–shell particles, a unique class of functional materials, have received increasing research interest for the past 2 decades owing to their exceptional performance in many technological fields. ...For catalysis, coating a core catalyst with a shell could effectively enhance core stability and catalytic activity, provide reactant/product selectivity, add stimuli-responsive smart features, and so forth. Despite the rapid advancement made for core–shell materials, it is rare to see such shells displaying more than one or two functional roles in a single reaction system. Herein, we have developed an amorphous Ni-MOF-74 coating process for a hollow sphere made of silica-supported Ni nanoparticles. Multifunctional catalysts prepared by integration of metal–organic frameworks (MOFs) and metals were mainly limited to noble metals, whereas our catalyst successfully integrates highly dispersed transition-metal nanoparticles with MOFs. Our MOF shell possesses four distinct functionalities for tandem imination: to prevent detachment and segregation of catalytic Ni nanoparticles, to act as an acid catalyst, to avoid over-hydrogenation of the desired product via molecular sieving, and to suppress the undesired byproduct via promoting competitive reaction with a size-sieveable product. As a result, this MOF shell enables Ni/SiO2 to serve as a potential alternative to noble metal catalysts in this tandem reaction, and chemical transformation of the reactant substrate to a targeted product can be achieved more effectively.
Cisplatin (CDDP) treatment is one of the most predominant chemotherapeutic strategies for patients with gastric cancer (GC). A better understanding of the mechanisms of CDDP resistance can greatly ...improve therapeutic efficacy in patients with GC. Circular RNAs (circRNAs) are a class of noncoding RNAs whose functions are related to the pathogenesis of cancer, but, in CDDP resistance of GC remains unknown.
circAKT3 (hsa_circ_0000199, a circRNA originating from exons 8, 9, 10, and 11 of the AKT3 gene) was identified by RNA sequencing and verified by quantitative reverse transcription PCR. The role of circAKT3 in CDDP resistance in GC was assessed both in vitro and in vivo. Luciferase reporter assay, biotin-coupled RNA pull-down and fluorescence in situ hybridization (FISH) were conducted to evaluate the interaction between circAKT3 and miR-198. Functional experiments were measured by western blotting, a cytotoxicity assay, clonogenic assay and flow cytometry.
The expression of circAKT3 was higher in CDDP-resistant GC tissues and cells than in CDDP-sensitive samples. The upregulation of circAKT3 in GC patients receiving CDDP therapy was significantly associated with aggressive characteristics and was an independent risk factor for disease-free survival (DFS). Our data indicated that circAKT3 promotes DNA damage repair and inhibits the apoptosis of GC cells in vivo and in vitro. Mechanistically, we verified that circAKT3 could promote PIK3R1 expression by sponging miR-198.
circAKT3 plays an important role in the resistance of GC to CDDP. Thus, our results highlight the potential of circAKT3 as a therapeutic target for GC patients receiving CDDP therapy.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
The 'long tail' nature of rural special education (RSE) suggests that it simultaneously possesses the private nature of discreteness and the public nature of externalities, which can easily cause ...provision insufficiency. However, this mismatch may have a dynamic intertemporal correction mechanism impacted by different expenditures of supply sectors (governments and other social sectors). This paper uses different models and data from 30 provinces in China from 2003-2014 to analyze this dynamic correction mechanism. This research finds that different kinds of expenditures from different suppliers have divergent effects on this correction. Capital expenses (especially infrastructure construction) have significantly positive effects on the correction, but administrative expenses have significant dual effects on the correction. These effects may be caused by the various governance efficiencies and motivations of all stakeholders in RSE. This paper concludes that we should pay more attention to the accurate recognition and effective satisfaction of RSE affected by the governance efficiency and motivation of different suppliers to achieve this dynamic correction.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
The thin structure that possesses both excellent stealth and load-bearing capabilities has a high demand in the military. This article proposes a multifunctional composite laminates, along with its ...optimization strategy. The novel structure comprises several layers of Glass Fiber Reinforced Plastics and each layer has a fixed thickness. The matrix of each layer is made of polymer dispersed with graphene oxide of varying volume fractions, which facilitates the transmission, absorption, and reflection of microwave. The multi-objective optimization strategy of composite laminates is conducted by considering the ply orientation and volume fraction of graphene oxide as design variables, and the bending stiffness and microwave absorbing bandwidth of the overall structure as design objectives, meanwhile the JAYA, a metaheuristic algorithm is employed as the optimizer. The results demonstrate that the optimization algorithm can efficiently adjust the structure to an optimal state. Furthermore, compared with the original structure, the optimized structure has a 190% increase in load-bearing capacity and a 30.3% increase in microwave absorbing performance. This method can be used for rapid design of aircraft stealth skins.
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•Algal growth increased first and then decreased with increasing MP concentrations.•Green MPs did not affect algal cell locomotion due to particle resemblance.•White MPs may inhibit ...the algal growth due to ethanol residue presence.•Daphnia cannot distinguish similar sized algae and MPs.•Algae will aggregate with MPs and did not affect Daphnia ingestion in long run.
Toxicities of microplastics (MPs) on aquatic organisms have been widely investigated often by using white or transparent MPs. However, various colored MPs scatter in the real aquatic environment. Here we investigated four colored MPs’ effects on Scenedesmus obliquus algal growth first. Under the light condition, algal growth increased initially due to hormesis stimulation and then decreased gradually at higher MP concentrations. Green colored MPs exhibited the lowest inhibition effect, probably due to their resemblance to algae; white MPs inhibited the algal growth significantly, which was attributed to the presence of ethanol. Turbulence condition seemed to diminish algal growth differences among groups, but it led to slight oxidative stress. Furthermore, we also tested MP effects on Daphnia magna feeding ability. Results indicated that daphnids were probably not able to distinguish colored MPs from algae. But their algae ingestion amounts increased when MPs reached to 40% of algal cells, probably because daphnids could widen their filtering gapes when food quality decreases. However, this phenomenon did not last until the 3rd day, as the agglomeration of MPs and algae made them settle down. Overall, our results highlighted the color may alter some MP effects and is necessary to be considered in (eco)toxicological studies.
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