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[Display omitted] • Approach for anchoring of Pt atoms on isolated Sn4+ is introduced. • Using this approach PtSn/SiO 2 (hexagonal mesoporous silica) catalysts were prepared. • Pt-Sn/atoms/sub nanoclusters were identified on the surface of catalysts. • The catalysts are active, selective, and stable in C 3 H 8 dehydrogenation to C 3 H 6. • Sn is essential to enhance H 2 desorption from Pt that is the rate-limiting step. Owing to propane availability in shale gas and the growing demand for propene, non-oxidative dehydrogenation of this alkane has attracted much attention. Although, catalysts with supported PtSn species are applied on the large scale, a further increase in their activity without loss in propene selectivity at low Pt content would certainly improve process economy. Herein, we introduce a molecularly defined strategy for controlling catalyst activity through anchoring of Pt atoms on isolated Sn4+ firmly confined in the framework of hexagonal mesoporous silica. In addition to the dispersion of Pt species, the presence of Sn4+ in close contact with Pt is essential for increasing the rate of propane dehydrogenation through enhancing H 2 desorption, which is the rate-limiting step. As the anchored Pt atoms/sub nanoclusters do not sinter under reducing conditions, the developed catalysts show high on-stream stability and propene selectivity of above 99 % under industrially relevant conditions. [ABSTRACT FROM AUTHOR]

[Display omitted] • Highly dispersed VO x species showed high apparent TOF value but low C 3 H 6 selectivity. • VO x species in low-polyvanadate form are deemed to be more active and stable in PDH. • VO x -C 3 H 5 species was speculated to be the important intermedia during PDH. • H 2 formation is deemed as the rate-limiting step over as-prepared V-HMS. Vanadium was introduced to hexagonal mesoporous SiO 2 (HMS) to prepare supported vanadium-based catalysts (V-HMS). Their catalytic performance in the non-oxidative propane dehydrogenation to propylene (PDH) was modulated with V surface density varying from 0.12 to 15.08V atom·nm−2. VO x species with different structure were analyzed by UV–vis spectroscopy, NH 3 -TPD, H 2 -TPR and XPS. High propylene space time yield of 0.73 kg·h−1·kg cat −1 and excellent regeneration behavior were achieved. Correlating VO x polymerization degree with catalytic performance, VO x aggregates, mainly in low-polyvanadate form, were established to reveal high intrinsic activity and stability in comparison with their counterparts, including isolated or/and highly polymerized VO x as well as V 2 O 5. Temporal analysis of products (TAP) identified hydrogen formation as the rate-limiting step in the PDH reaction. In-situ DRIFTS was employed to investigate the reaction mechanism. V species containing C=C bond, i.e., VO x -C 3 H 5 , was proposed to be an intermediate of gas-phase propylene. [ABSTRACT FROM AUTHOR]

[Display omitted] • Co/ZrO 2 catalysts with single Co2+ are efficient for C 3 H 8 dehydrogenation to C 3 H 6. • 1Co/ZrO 2 performed durable over multiple dehydrogenation/regeneration cycles. • 1Co/ZrO 2 showed higher activity than a commercial analogue of K-CrO x /Al 2 O 3. • The high activity results from a synergy effect between Co2+ and Zr cus. • Recombination of surface H species is the rate-limiting step in C 3 H 6 formation. Due to the increased production of shale gas containing propane, the share of non-oxidative propane dehydrogenation (PDH) in the large-scale production of propene is expected to continue to grow. There are, however, some ecofriendly and cost shortcomings associated with the currently applied Cr- or Pt-containing catalysts. Against this background, we present here Co/ZrO 2 alternatives and reveal the fundamentals affecting their activity, which can be used for purposeful catalyst design. Co2+ species homogeneously distributed within the lattice of ZrO 2 significantly increase the activity of coordinatively unsaturated Zr4+ for the PDH reaction. The increase is caused by accelerating both the cleavage of CH bonds in propane and the recombination of surface H species, with the latter reaction being the rate-limiting step. The best-performing catalyst outperformed an analogue of commercial K-CrO x /Al 2 O 3 in terms of the rate of propene formation and demonstrated durable performance over a series of 10 PDH/regeneration cycles under industrially relevant conditions. It also outperformed most previously developed Co-containing catalysts in terms of propene productivity. The space–time yield of propene formation achieved at 57 % equilibrium propane conversion at 550 °C was 0.71 kg·h−1·kg cat -1. [ABSTRACT FROM AUTHOR]

Inefficient irrigation practices have hindered crop yields, wasted irrigation water resources, and posed threats to groundwater levels and agricultural sustainability. This study evaluated different irrigation strategies for a winter wheat-summer maize rotation system to identify sustainable practices for maintaining yields while reducing groundwater depletion. A two-year field experiment was conducted, implementing three optimized irrigation strategies during the winter wheat season: I-4 (irrigated until the soil water content (SWC) of the 40 cm soil layer reaches 60% of field capacity (FC), I-6 (irrigated until the SWC of the 60 cm soil layer reaches 80% FC), and a rainfed (R) as control. Irrigation was repeated when the SWC dropped to the specified level. No irrigation level was used during the summer maize season, except for irrigation after sowing that ensuring the normal emergence of maize. WHCNS (Water Heat Carbon Nitrogen Simulator) model was developed to simulate soil water dynamics, field water consumption, and yield of both crops. The result indicated WHCNS model accurately simulated water dynamics, consumption, and grain yield. Compared to R treatment, the I-4 treatment significantly increased annual crop yield by 19.83%–28.65% (p < 0.05), while maintaining similar crop water productivity. Furthermore, the I-4 treatment achieved comparable yields to the I-6 treatment, but with a 33.91% reduction in irrigation water use, resulting in a 33.46% increase in crop water productivity and a 90.53% increase in irrigation water productivity. From a sustainable perspective, the I-4 treatment effectively reduced field water losses and maintained relatively high soil water storage, particularly in the topsoil, which was beneficial for the early growth of subsequent crops. The R treatment greatly contributed to groundwater recharge when precipitation was sufficient, while it led to severe yield losses. Overall, under the condition of annual rotation planting systems, the I-4 treatment sustainably maintained yields with less irrigation, decreasing groundwater consumption. This approach could conserve regional water resources and groundwater table while upholding agricultural productivity and achieving system sustainable water use. [Display omitted] • WHCNS model simulated soil water dynamics, field water consumption, and yield well. • I-4 reduced irrigation water by 33.91% and increased water productivity by 33.46%. • I-4 maintained topsoil moisture, beneficial for subsequent crops. • Water-saving irrigation use less groundwater, achieving sustainable agriculture. [ABSTRACT FROM AUTHOR]

[Display omitted] • Alkali metal in MnO x -M 2 WO 4 /SiO 2 affects activity under anaerobic conditions. • Lattice oxygen of MnO x -M 2 WO 4 /SiO 2 can convert CH 4 to hydrocarbons. • OCM over MnO x -M 2 WO 4 /SiO 2 and M 2 WO 4 /SiO 2 proceeds via adsorbed oxygen species. • Presence of MnO x does not create more active sites but changes their reactivity. This work unveils the fundamentals relevant for activity and product selectivity in the oxidative coupling of methane (OCM) over the (MnO x)-M 2 WO 4 /SiO 2 (M = Na, K, Rb, or Cs) catalysts. The presence of the molten phase of Na 2 WO 4 and the ability of the catalysts to release lattice oxygen were not found to be the performance-governing factors. As proven by oxygen isotopic exchange experiments combined with thorough catalytic tests, the performance of both tri- and bimetallic catalysts is defined by the involvement of adsorbed oxygen species formed from gas-phase O 2. Lattice oxygen of M 2 WO 4 /SiO 2 is not capable of converting CH 4 to C 2 H 6 , while that of MnO x -M 2 WO 4 /SiO 2 is active for this reaction. The OCM activity of M 2 WO 4 /SiO 2 decreases with the atomic weight of alkali metal, whereas there is no such effect in the presence of MnO x , which, however, increases the activity. The enhancing effect was explained by improving the active site turnover. [ABSTRACT FROM AUTHOR]

Many trait-specific countermeasures to face spoofing attacks have been developed for security of face authentication. However, there is no superior face anti-spoofing technique to deal with every kind of spoofing attack in varying scenarios. In order to improve the generalization ability of face anti-spoofing approaches, an extendable multi-cues integration framework for face anti-spoofing using a hierarchical neural network is proposed, which can fuse image quality cues and motion cues for liveness detection. Shearlet is utilized to develop an image quality-based liveness feature. Dense optical flow is utilized to extract motion-based liveness features. A bottleneck feature fusion strategy can integrate different liveness features effectively. The proposed approach was evaluated on three public face anti-spoofing databases. A half total error rate (HTER) of 0% and an equal error rate (EER) of 0% were achieved on both REPLAY-ATTACK database and 3D-MAD database. An EER of 5.83% was achieved on CASIA-FASD database. [ABSTRACT FROM AUTHOR]

Background The differentiation of endothelial progenitor cells (EPCs) plays a pivotal role in endothelial repair and re-endothelialization after vascular injury. However, the underlying mechanisms still remain largely elusive. Here, we investigated the role of the novel C2H2 zinc finger transcription factor ZFP580 in EPC differentiation and the molecular mechanisms behind EPC-mediated endothelial repair. Methods Bone marrow-derived EPCs were isolated, cultured, and identified. EPCs were infected with an adenovirus encoding ZFP580 or Ad-siRNA to silence ZFP580. Fluorescence-activated cell sorting (FACS) analysis was performed to analyze EPC surface makers. The expression of ZFP580, eNOS, VEGFR-2, CD31, CD34, CD45 and vWF was performed by Q-PCR, Western blot and immunostaining. NO donor SNAP or NOS inhibitor L-NAME was used to elucidate the possible molecular mechanism. Tube formation in vitro and angiogenesis assay in vivo were also used in this study. Results Both ZFP580 and eNOS were displayed dynamic expression during EPC differentiation. Overexpression of ZFP580 enhanced EPC differentiation, while knockdown suppressed it. ZFP580 also enhanced eNOS expression, and eNOS inhibition suppressed differentiation. Upregulation/knockdown of ZFP580 also enhanced/reduced endothelial tube formation from EPC in vitro, and angiogenesis in vivo in response to Matrigel plugs containing EPC. Conclusions ZFP580 promotes not only the differentiation of EPCs into ECs by increasing the expression of eNOS and the availability of nitric oxide, but also the vessel formation in vitro and in vivo. This might represent a novel mechanism of ZFP580 in EPC differentiation and its therapeutic value in the treatment of vascular disease. [ABSTRACT FROM AUTHOR]

[Display omitted] • The dependence of the rate of propene formation on Ga/Zr ratio over Ga 2 O 3 /ZrO 2 was determined for PDH. • The reaction intermediates and mechanism were studied by in-situ DRIFTS and DFT calculations. • GaⅡ–O 3c Ⅱ structure was determined as the active site with enhanced C–H bond activation ability over Ga 2 O 3 /ZrO 2. • Ga 2 O 3 /ZrO 2 catalyst showed a good reaction-regeneration stability. ZrO 2 -based catalysts have attracted extensive attention in propane dehydrogenation (PDH) owing to their environmental compatibility, low costs, and superior catalytic performance. However, the structure–activity relationship and mechanistic analysis of Ga 2 O 3 /ZrO 2 in PDH are rarely studied where GaO x either acts as an active site or a promoter. Here, Ga 2 O 3 /ZrO 2 catalysts with different Ga/Zr ratios were synthesized by the impregnation technique, and the structure–activity relationship was revealed by combining complementary in/ex-situ characterization methods with catalytic tests. It is found the rate of propene formation first increases linearly and then reaches a plateau with the increase of Ga 2 O 3 loading, such activity-loading dependence is related to the evolution of Ga 2 O 3 species varying from monodisperse to single-layer and then multilayer states. Activation energy and C 3 H 8 -TPSR results suggest the formation of a new active site with high intrinsic activity over Ga 2 O 3 /ZrO 2. Furthermore, the molecular level reaction mechanism of Ga 2 O 3 /ZrO 2 in PDH was studied by DFT calculations, which pointed out the active site structure was GaⅡ–O 3c Ⅱ site exhibiting enhanced activation ability toward C–H bond and lower reaction barrier compared with bare ZrO 2. This work is expected to offer new insights into understanding the structure–activity relationships over ZrO 2 -based catalysts for PDH reaction. [ABSTRACT FROM AUTHOR]

[Display omitted] • The performance of Mn-Na 2 WO 4 /SiO 2 catalysts in CL-OCM can be significantly improved by cofed water. • Water does not alter the scheme of product formation but influences their kinetics. • Water facilitates the releasability of lattice oxygen. • The role of MnO x and Na 2 WO 4 is shown by in situ XRD and UV–vis spectroscopy. The oxidative coupling of methane (OCM) to C 2 H 6 and C 2 H 4 (C 2 -hydrocarbons) is an industrially attractive reaction, which has not yet been commercialized. Apart from the low selectivity to C 2 -hydrocarbons at high degrees of CH 4 conversion, another substantial drawback is the necessity to use pure O 2 when this oxidant and methane are cofed. Original OCM studies used an approach called chemical looping OCM (CL-OCM) that consists of alternating feeding of methane and air for product formation and catalyst reoxidation, respectively. The developed catalysts, however, suffer from their low ability to provide lattice oxygen for the desired reaction. Herein, we demonstrate that this catalyst property can be significantly improved when performing CL-OCM over Mn-Na 2 WO 4 /SiO 2 catalysts in the presence of water. In comparison to water-free CL-OCM, both methane conversion and C 2 -hydrocarbons selectivity increase resulting in at least doubling of the yield of these products. The selectivity to ethylene of about 53 % was obtained at about 24 % CH 4 conversion. The total selectivity to C 2 -hydrocarbons was about 76 %. The analysis of selectivity-conversion relationships for C 2 H 4 , C 2 H 6 , CO and CO 2 proved that water does not alter their general formation pathways but influences the kinetics of their formation. In situ X-ray diffraction, in situ UV–vis spectroscopic, and temperature-programmed tests (H 2 -TPR and O 2 -TPD with or without cofed H 2 O) showed that Mn 2 O 3 acts as the oxygen carrier in CL-OCM. In-situ DRIFTS proved the presence of O 2 – and O 2 2–. They can interact with water yielding OH radicals that accelerate CH 4 conversion. [ABSTRACT FROM AUTHOR]