Search

Exploring high efficient and cost-effective electrocatalysts for oxygen evolution reaction is a determination step towards sustainable green energy applications. Polyoxometalates and layered double hydroxide materials are suggested to be potential catalyst materials; however, those electrocatalytic behaviors are greatly inferior to the state-of-the-art OER electrocatalysts (RuO2 and IrO2). In this work, we employ a self-assembly approach in which polyoxometalate anions are successfully intercalated into NiFe layered double hydroxide. Upon analysis of the composition, the elemental valence state and the infrared spectrum, it confirms that the intercalated polyoxometalate anions in the layers of NiFe layered double hydroxide are in the format of PW12O403−. Even though the partial anions in the as-prepared intercalation NiFe layered double hydroxide are only polyoxometalate anions, its electrochemical performance surpasses the counterpart precursor NiFe layered double hydroxide (NO3−) in many aspects, such as turnover frequencies, overpotentials, kinetics, and stability. The introduction of polyoxometalate anions can optimize the local electronic structure which enhances the charge transport capacity of NiFe layered double hydroxide as well as alter the adsorption/desorption nature of the intermediates during the catalysis process. This work provides a new strategy to boost the OER activity of layered double hydroxide-based electrocatalysts.

Defect engineering has been used to develop low-cost and effective catalysts to boost oxygen reduction reactions. However, the development of catalysts that use metal cation vacancies as the active sites for oxygen reduction reaction is lacking. In this study, ZnS nanoparticles on N-doped carbon serve as an oxygen reduction reaction catalyst. These catalysts were prepared via a one-step method at 900 °C. Amazingly, the high-resolution transmission electron microscope image revealed obvious defects in the ZnS nanoparticles. These facilitated the catalyst synthesis, and the product displayed good electrocatalytic performance for the oxygen reduction reaction in an alkaline medium, including a lower onset potential, lower mid-wave potential, four electron transfer process, and better durability compared with 20 wt% Pt/C. More importantly, the density functional theory results indicated that using the Zn vacancies in the prepared catalyst as active sites required a lower reaction energy to produce OOH* from *OO toward oxygen reduction reaction. Therefore, the proposed catalyst with Zn vacancies can be used as a potential electrocatalyst and may be substitutes for Pt-based catalysts in fuel cells, given the novel catalyst's resulting performance.

Acetylene chemical process, especially catalyzing acetylene acetoxylation for the synthesis of vinyl acetate (VAc), has attracted wide attention in coal-rich countries. Although great efforts have been made to prepare different catalysts to improve the VAc synthesis via acetylene acetoxylation, the acetic acid (HAc) conversion cannot achieve a satisfactory level, much lower than 60%. Herein, ZnO nanoparticles in situ wrapped on zinc-nitrogen-carbon materials (ZnO@ Zn–N–C) have been successfully synthesized. Due to the simultaneous presence of nitrogen and carbon in chitosan, the obtained carbon material achieved in situ nitrogen doping during the high-temperature treatment. Furthermore, the as-obtained ZnO@Zn–N–C exhibits high specific surface area of 1430.1 m2/g and pore volume of 0.92 cm3/g, because Zn composites have the ability to etch carbon to form pores. In particular, ZnO@Zn–N–C displays an amazing catalytic activity for acetylene acetoxylation to synthesize VAc with the HAc conversion high up to 88.8%, which is much higher than those reported in other papers before.

High active and durable non-noble metal electrocatalysts are urgently developed to satisfy the high performance oxygen reduction reaction (ORR). We successfully synthesized Co-CoOx anchored on nitrogen-doped carbon via a facile sand-bath method (SBM), i.e., Co-CoOx/N-C (SBM). The as-obtained Co-CoOx/N-C (SBM) exhibited overwhelming superiorities to Co-CoO/N-C prepared by conventional heat treatment (CHT), particularly in electrochemical performance of ORR. Although Co-CoOx/N-C (SBM) showed smaller specific surface area of 276.8 m2/g than that of 939.5 m2/g from Co-CoO/N-C (CHT), the Co-CoOx/N-C (SBM) performed larger pore diameter and more Co3O4 active component resulting in better ORR performance in 0.1 mol/L KOH solution. The Co-CoOx/N-C (SBM) delivered onset potential of 0.91 V vs. RHE, mid-wave potential of 0.85 V vs. RHE and limited current density of 5.46 mA/cm2 much better than those of the Co-CoO/N-C (CHT). Furthermore, Co-CoOx/N-C (SBM) showed greater stability and better methanol tolerance superior to the commercial 20 wt% Pt/C.

In this paper, we study diagonal dominance of the stiffness matrix resulted from the piecewise linear finite element discretisation of the integral fractional Laplacian under global homogeneous Dirichlet boundary condition in one spatial dimension. We first derive the exact form of this matrix in the frequency space which is extendable to multi-dimensional rectangular elements. Then we give the complete answer when the stiffness matrix can be strictly diagonally dominant. As one application, we apply this notion to the construction of maximum principle preserving schemes for the fractional-in-space Allen–Cahn equation, and provide ample numerical results to verify our findings.

BackgroundAbscisic acid (ABA) plays an important role in plant growth and adaptation through the ABA signaling pathway. The ABA-responsive element binding (AREB/ABF) family transcriptional factors are central regulators that integrate ABA signaling with various signaling pathways. It has long been known that ABA inhibits rhizobial infection and nodule formation in legumes, but the underlying molecular mechanisms remain elusive.ResultsHere, we show that nodulation is very sensitive to ABA and exogenous ABA dramatically inhibits rhizobial infection and nodule formation in soybean. In addition, we proved that GmbZIP1, an AREB/ABF transcription factor, is a major regulator in both nodulation and plant response to ABA in soybean.GmbZIP1was specifically expressed during nodule formation and development. Overexpression ofGmbZIP1resulted in reduced rhizobial infection and decreased nodule number. Furthermore,GmbZIP1is responsive to ABA, and ectopic overexpression ofGmbZIP1increased sensitivity of Arabidopsis plants to ABA during seed germination and postgerminative growth, and conferred enhanced drought tolerance of plants. Remarkably, we found that GmbZIP1 directly binds to the promoter ofGmENOD40–1, a marker gene for nodule formation, to repress its expression.ConclusionOur results identified GmbZIP1 as a node regulator that integrates ABA signaling with nodulation signaling to negatively regulate nodule formation.

In this paper, we developed a simple two-step route to prepare a PdO/SnO2 heterostructure with the diameter of the SnO2 and PdO nanoparticles at about 15 nm and 3 nm, respectively. In the evaluation temperature window between 80 °C and 340 °C, PdO/SnO2 shows the best response to 100 ppm of CO at 100 °C with fast response time (14 s) and recovery time (8 s). Furthermore, the PdO/SnO2 nanoparticles exhibit a low detection limit and good selectivity to CO against interfering gases as well as rarely-seen low-temperature stability and reversibility. Such enhanced gas sensing performance could be attributed to both the ultrafine structure of PdO and the synergy between PdO and SnO2. The results clearly indicate the application of PdO/SnO2 as a pratical low-temperature sensing material for CO.

Cartilage tissue engineering has become the trend of cartilage defect repair owing to the engineered biomimetic tissue that can mimic the structural, biological and functional characteristics of natural cartilage. Biomaterials with high biocompatibility and regeneration capacity are expected to be used in cartilage tissue engineering. Herein, in this study, a dual-network bovine serum albumin/sodium alginate with hydroxyapatite nanowires composite (B-S-H) hydrogel scaffold has been prepared for cartilage repair. The obtained B-S-H hydrogel scaffold exhibits ideal physical properties, such as excellent mechanical strength, high porosity and swelling ratio, as well as the excellent biological activity to promote the human bone marrow derived mesenchymal stem cells (hBMSCs) proliferation and differentiation. The in vivo study further shows that the B-S -H hydrogel scaffold can obviously promote the generation of new cartilage that integrates well with surrounding tissues and is similar to adjacent cartilage in terms of thickness. It is considered that the B-S-H hydrogel scaffold has great potential in the application of cartilage defects repair.

In this work, we apply a fast and accurate numerical method for solving fractional reaction-diffusion equations in unbounded domains. By using the Fourier-like spectral approach in space, this method can effectively handle the fractional Laplace operator, leading to a fully diagonal representation of the fractional Laplacian. To fully discretize the underlying nonlinear reaction-diffusion systems, we propose to use an accurate time marching scheme based on ETDRK4. Numerical examples are presented to illustrate the effectiveness of the proposed method., Comment: 23 pages

Half-Heusler compounds usually exhibit relatively higher lattice thermal conductivity that is undesirable for thermoelectric applications. Here we demonstrate by first-principles calculations and Boltzmann transport theory that the BiBaK system is an exception, which has rather low thermal conductivity as evidenced by very small phonon group velocity and relaxation time. Detailed analysis indicates that the heavy Bi and Ba atoms form a cage-like structure, inside which the light K atom rattles with larger atomic displacement parameters. In combination with its good electronic transport properties, the BiBaK shows a maximum n-type ZT value of 1.9 at 900 K, which outperforms most half-Heusler thermoelectric materials.

The rapid increase in rubber monoculture in Xishuangbanna has resulted in extensive damage to its local ecosystem. To decrease the negative effects, the concept of the ecological-economic rubber plantation (EERP) system was proposed. The EERP entails intercropping rubber plants with other economically significant plants, which would not only decrease the ecological impact of the rubber plantation, but also maintain and potentially increase its profitability compared with rubber monocultures. In order to select the appropriate species and intercropping pattern in the EERP system, we compared the photosynthetic parameters of five economically important trees (Swietenia mahagoni, Coffea arabica, Mesua ferrea, Myristica yunnanensis and Paramichelia baillonii) under four irradiance levels. The optimal irradiance intensity of C. arabica and M. yunnanensis was approximately 40%, and these species can be planted in the understory of an 8- to 15-year-old rubber forest. Adult S. mahagoni, M. ferrea and P. baillonii grow taller than the rubber trees, and their seedlings also show superior performance in 100% irradiance than in other irradiances. Thus, in an EERP, these valuable trees could be planted adjacent to rubber plantations but on sites that are economically and environmentally marginal for rubber production.

This work is concerned with spectral collocation methods for fractional PDEs in unbounded domains. The method consists of expanding the solution with proper global basis functions and imposing collocation conditions on the Gauss-Hermite points. In this work, two Hermite-type functions are employed to serve as basis functions. Our main task is to find corresponding differentiation matrices which are computed recursively. Two important issues relevant to condition numbers and scaling factors will be discussed. Applications of the spectral collocation methods to multi-term fractional PDEs are also presented. Several numerical examples are carried out to demonstrate the effectiveness of the proposed methods.

The paired box 6 (Pax6) gene encodes a transcription factor essential for eye development in a wide range of animal lineages. Here we describe the cloning and characterization of Pax6 gene from the blind hydrothermal vent tubeworm Ridgeia piscesae (RpPax6). The deduced RpPax6 protein shares extensive sequence identity with Pax6 proteins from other species and contains both the paired domain and a complete homeodomain. Phylogenetic analysis indicates that it clusters with the corresponding sequence from the closely related species Platynereis dumerilii (P. dumerilii) of Annelida. Luciferase reporter assay indicate that RpPax6 protein suppresses the transcription of sine oculis (so) in D. melanogaster, interfering with the C-terminal of RpPax6. Taking advantage of Drosophila model, we show that RpPax6 expression is not able to rescue small eye phenotype of ey2 mutant, only to cause a more severe headless phenotype. In addition, RpPax6 expression induced apoptosis and inhibition of apoptosis can partially rescue RpPax6-induced headless phenotype. We provide evidence RpPax6 plays at least two roles: it blocks the expression of later-acting transcription factors in the eye development cascade, and it promotes cell apoptosis. Our results indicate alternation of the Pax6 function may be one of the possible causes that lead the eye absence in vestimentiferan tubeworms.