Search

Oxidative dehydrogenation of propane (ODHP) is a reaction with significant practical significance. As for the industrial application of ODHP, it is challenging to achieve high activity and high propylene selectivity simultaneously. In this study, to overcome this obstacle, we designed a series of Cu/BN catalysts with unique morphologies for establishing a photothermal ODHP system with high efficiency and selectivity. Characterization and evaluation results revealed that Cu/BN-NS and Cu/BN-NF with enlarged specific surface areas exhibited higher catalytic activities. The localized surface plasmon resonance (LSPR) effect of Cu nanoparticles further enhanced the photothermal catalytic performances of Cu/BN catalysts under visible light irradiation. To the best of our knowledge, it is the first time to establish a BNbased photothermal ODHP catalytic system. This study is expected to pave pathways to realize high activity and propylene selectivity for the practical application of ODHP. [ABSTRACT FROM AUTHOR]

O2-Assisted oxidative dehydrogenation of propane (O2-ODHP) could convert abundant shale gas into propylene as an important chemical raw material, meaning O2-ODHP has practical significance. Thermodynamically, high temperature is beneficial for O2-ODHP; however, high reaction temperature always causes the overoxidation of propylene, leading to a decline in its selectivity. In this regard, it is crucial to achieve low temperatures while maintaining high efficiency and selectivity during O2-ODHP. The use of catalytic technology provides more opportunities for achieving high-efficiency O2-ODHP under mild conditions. Up to now, many kinds of catalytic systems have been elaborately designed, including transition metal oxide catalysts (such as vanadium-based catalysts, molybdenum-based catalysts, etc.), transition metal-based catalysts (such as Pt nanoclusters), rare earth metal oxide catalysts (especially CeO2 related catalysts), and non-metallic catalysts (BN, other B-containing catalysts, and C-based catalysts). In this review, we have summarized the development progress of mainstream catalysts in O2-ODHP, aiming at providing a clear picture to the catalysis community and advancing this research field further. [ABSTRACT FROM AUTHOR]

Controlling the nanoparticle‐cell membrane interaction to achieve easy and fast membrane anchoring and cellular internalization is of great importance in a variety of biomedical applications. Here we report a simple and versatile strategy to maneuver the nanoparticle‐cell membrane interaction by creating a tunable hydrophobic protrusion on Janus particles through swelling‐induced symmetry breaking. When the Janus particle contacts cell membrane, the protrusion will induce membrane wrapping, leading the particles to docking to the membrane, followed by drawing the whole particles into the cell. The efficiencies of both membrane anchoring and cellular internalization can be promoted by optimizing the size of the protrusion. In vitro, the Janus particles can quickly anchor to the cell membrane in 1 h and be internalized within 24 h, regardless of the types of cells involved. In vivo, the Janus particles can effectively anchor to the brain and skin tissues to provide a high retention in these tissues after intracerebroventricular, intrahippocampal, or subcutaneous injection. This strategy involving the creation of a hydrophobic protrusion on Janus particles to tune the cell‐membrane interaction holds great potential in nanoparticle‐based biomedical applications. [ABSTRACT FROM AUTHOR]

In this work, Sn-Si mixed oxide microspheres with concave hollow morphologies were first synthesized by a simple aerosol method using the very common commercial surfactant cetyl trimethyl ammonium bromide (CTAB) as a template, and then highly interconnected mesoporous and hollow Sn-Si mixed oxide microspheres were synthesized via an alkali (NaOH) treatment in the presence of CTAB. The results show that CTAB plays a crucial role not only in forming hollow morphologies during the aerosol process, but also protecting the amorphous framework and thus preventing the excessive loss of Sn species during the NaOH treatment. More importantly, it widens mesoporous distribution and forms interconnected mesoporous channels. The catalytic performance of Baeyer–Villiger oxidation on the interconnected mesoporous and hollow Sn-Si mixed oxide microspheres with 2-adamantanone and hydrogen peroxide was 9.4 times higher than that of the sample synthesized without the addition of CTAB; 2.3 times that of the untreated parent, which was due to the excellent diffusion properties derived from the hollow and interconnected mesopore structure. This method is mild, simple, low-cost, and can be continuously produced, which has the prospect of industrial application. Furthermore, the fundamentals of this study provide new insights for the rational design and preparation of highly interlinked mesoporous and hollow metal-oxides with unique catalytic performances. [ABSTRACT FROM AUTHOR]

The trace amount of CO in H2-rich gas poisons Pt electrode when it is adopted as feedstock for proton-exchange-membrane fuel cells. Preferential oxidation of CO (PROX) is a promising approach to selectively oxidize the trace amount of CO while keeping H2 unoxidized. Catalyst plays important roles in PROX. To date, enormous catalysts have been developed for PROX. Summarizing the catalysts developed for PROX and unveiling the reaction mechanism could definitely advance this research field. Herein, in this review, according to the nature of the active sites on the catalysts, we classify the catalysts into group VIII metal-based catalyst, group IB metal-based catalysts, group VIII-group IB bimetallic catalysts, transitional metal oxide catalysts as well as others, describe the progress of the catalysts in PROX in the latest five years, and extract the underlying reaction mechanism, with the aim to provide guidance for the rational design of efficient catalysts in the future. [ABSTRACT FROM AUTHOR]

In this paper, a set of master equations of a cold atom-molecule system including the manipulation of an external rotating magnetic field and laser signal under a mean-field approximation was developed. We discovered that external manipulation can be characterized by a single regulating term. After considering the realizability and necessity of the regulating term for system manipulation, we separated the molecule preparation procedure into three stages: the phase transforming, descending and stable stages. In each stage, the regulating term's qualities were analyzed. Further, we discovered that, under certain situations, this system cannot enter the pure molecular state in a stable manner, regardless of whether it is regulated or not. Finally, an approach was proposed for the rapid preparation of cold molecules. [ABSTRACT FROM AUTHOR]

Photo-catalytically converting the greenhouse gas CO2 into ethanol is an important avenue for the mitigation of climate issues and the utilization of renewable energies. Catalysts play critical roles in the reaction of photocatalytic CO2 conversion to ethanol, and a number of catalysts have been investigated, including semiconductors and plasmonic metal-based catalysts, as well as several other catalysts. In this review, the progress in the development of each category of catalysts is summarized, the current status is reviewed, the remaining challenges are pointed out, and the future research directions are prospected, with the aim being to pave pathways for the rational design of better catalysts. [ABSTRACT FROM AUTHOR]

This study aimed to investigate the Cavitation dynamics of Hydrodynamic-acoustic cavitation by employing experimental methods. The spatial distribution of cavitation clouds, the temporal and spatial distribution achieved by cavitation clouds, and the main flow structure in the flow field were extracted and analyzed by complying with the cavitating flow image captured with the high-speed camera. As indicated from the results, the widened cavitation region and the strength of cavitation under the synergy of ultrasound were reported. When the inlet pressure is 2 MPa, the average value of the volume-averaging cavitation intensity variable is 0.029, 0.058, and 0.092, respectively, and the corresponding growth rate is 95% and 58.5%. By adopting the Proper Orthogonal Decomposition method (POD), the ultrasound was revealed to primarily enhance the cavitation intensity by downregulating the cavitation threshold other than altering the large-scale vortex structure in the flow field. The high-frequency pressure pulsation of ultrasound strengthened the instability exhibited by the shear layer and induced small-scale vortex structures at the shear layer, which was suggested to be the more violently shed and collapse. [ABSTRACT FROM AUTHOR]

The Low Earth orbit Remote Sensing (LRS) satellite network is envisioned as an essential component of bolstering space information applications, thus extending conventional ground information applications to the on-board space information applications. However, it inevitably faces grave challenges imposed by the dynamics of the satellite network's topology, by the intermittence of Inter-Satellite communication Links (ISLs) as well as by the mobility-induced satellite-access switching of mobile terminals. Hence, this is a very different networking landscape from that of the terrestrial Internet. Against these challenging problems, we propose a resilient networking architecture for LRS Satellite Networks (LRS-SNs), with special emphasis on their dynamic routing, resilient transmission and their intrinsic mobility. Specifically, path-quality aided and lifetime-aware dynamic routing is proposed for enhancing the routing against dynamic topology changes. Hop-by-hop data transmission is relied upon for providing transmission resilience against ISL intermittence. Furthermore, data caching is invoked for providing resilience against intermittent communications imposed by dynamic satellite access switching. We employ a semi-physical simulation platform for evaluating the achievable performance of the proposed resilient network architecture. [ABSTRACT FROM AUTHOR]

Magnetic nanoparticles are widely utilized in smart materials, the most well-known application being magnetorheological fluids. In this paper, a comprehensive numerical model of magnetic nanoparticles and the carrier fluid interactions is presented. The soft sphere model approach is adopted to simulate the nanoparticle interactions at a coarse molecular level, with the consideration of both contact and noncontact particle interactions. Magnetic dipole theory is used to simulate the particle behavior under external magnetic fields. The carrier fluid flow is solved using the computational fluid dynamics approach with a two-way coupling with the nanoparticles. Based on the present model, simulations have been conducted for both static fluid and dynamic double-shear flow cases. Without the presence of an external magnetic field, local particle clusters are formed as a result of van der Waals attraction between the particles. When the external magnetic field is present, chain-like structures of nanoparticles are observed for both the static and dynamic cases parallel to the direction of the applied magnetic field. For the static case, the formation of the chain-like structures is rapid, and “steady state” is reached within a short time (∼1 ms). In the double-shear flow case, the chain-like structures are found to be much thinner and shorter than the static case. The developed model provides a fundamental understanding of the real physics of magnetic nanoparticles and carrier fluid interactions. It also enables future investigations in optimizing physical and transport properties of smart materials. [ABSTRACT FROM PUBLISHER]

Photothermal synergistic CO 2 reforming of CH 4 (CRM) is a promising avenue to convert the greenhouse gases (CO 2 and CH 4) into valuable chemicals and store the abundant clean solar energy into chemical energy simultaneously. Developing photothermal catalysts that could drive CRM efficiently at low temperatures remains as a challenge. In the present study, Nb 2 O 5 supported group VIII metal catalysts (M/Nb 2 O 5) were synthesized, with the typical catalyst Rh/Nb 2 O 5 recording a CO 2 conversion rate of 50.6 mmol g Rh −1 min−1 in CRM at 500 °C under visible light irradiation, about double fold higher than that achieved under the thermal-driven reaction condition. Mechanism study disclosed that oxygen vacancy was generated in situ over M/Nb 2 O 5 under the CRM reaction atmosphere. The oxygen vacancy promoted CO 2 adsorption and enhanced the light harvesting capacities of M/Nb 2 O 5 catalysts, which ultimately boosted their activities in photothermal CRM. This study provides a promising pathway for the rational design of efficient catalysts by tailoring the properties of the catalysts under the reaction atmosphere. • Oxygen vacancies could be generated in situ over M/Nb 2 O 5 catalysts in CRM. • Oxygen vacancy promoted catalyst light harvesting capacity and the activation of CO 2. • M/Nb 2 O 5 catalysts recorded a higher performance in CRM with visible light assistance. [ABSTRACT FROM AUTHOR]