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Here, we investigate the role of SmERF73, a group VII ETHYLENE RESPONSE FACTOR stress response transcription factor, in the regulation of post-modification of the skeleton precursors of diterpene tanshinones in Salvia miltiorrhiza. Most genes found to be involved in tanshinone biosynthesis are located on chromosome 6, and five of these genes comprise a large gene cluster in S. miltiorrhiza. We found that SmERF73 overexpression in S. miltiorrhiza coordinately up-regulated the transcription of seven tanshinone biosynthetic genes, four of which were located in the tanshinone gene cluster, consequently increasing tanshinone accumulation, while SmERF73 silencing reduced corresponding gene transcription and tanshinone accumulation. SmERF73 recognizes GCC-box promoter elements of four tanshinone-associated genes (DXR1, CPS1, KSL1 and CYP76AH3) and activates their expression. Moreover, SmERF73 and its targets were up-regulated by stress elicitors; SmERF73 appears to be at least partly mediated by the jasmonic acid (JA) signaling pathway via interaction with SmJAZ3. SmERF73 coordinately regulates tanshinone biosynthetic gene expression, suggesting a potential link between tanshinone production and plant stress responses.

The reasonable design and preparation of cheap, Earth-abundant, efficient, and durable heterogeneous electrocatalytic materials are a probable solution to the key problems of energy shortages and e...

The separation of C2 H2 from C2 H4 is one of the most challenging tasks due to the similarity of their physical properties. In addition, green synthetic protocol and adsorbent's stability are also the major concerns during the separation. Herein, under hydrothermal green synthesis conditions, an ultrastable ultramicroporous Zn-MOF was designed and synthesized with a high yield. The pore diameter of the Zn-MOF is 3.6 A, which lies in between the diameters of C2 H2 (3.3 A) and C2 H4 (4.2 A) molecules, leading to an efficient separation of the C2 H2 /C2 H4 mixtures by the sieving effect. The practical separation performance of C2 H2 /C2 H4 was confirmed by the dynamic breakthrough experiments. Moreover, the high stability enables the adsorption capacity of the Zn-MOF to C2 H2 , which can be maintained under a wide range of pH (1-13). Molecular simulations were also performed to identify the different C2 H2 - and C2 H4 -binding sites in Zn-MOF.

Lanthanide (Ln) metal–organic frameworks (Ln-MOFs) have attracted attention in anti-counterfeiting and white light-emitting diodes (WLEDs) due to their high quantum efficiency, long lifetimes, and characteristic linear spectrum. However, Ln-MOFs have some disadvantages, such as harsh luminescence modulation, low transparency, and poor film formation. In this study, Ln-MOF (Ln = Eu and/or Tb)-modified TEMPO-oxidized cellulose nanofibrils were employed for preparing transparent nanopapers and luminescence modulation. These luminescent nanopapers achieved an excellent light emission color tuning from green, yellow, and red under 365 nm excitation, while 254 nm radiation on these nanopapers only emitted characteristic pink light. Thus, the luminescent nanopapers combined color-tuning and photo-switching properties through the control of Eu³⁺/Tb³⁺ molar ratio and excitation wavelength (λEₓ at 365 and 254 nm), respectively, which greatly improved them for anti-counterfeiting applications. In addition, Ln-MOFs endowed these nanopapers with excellent optical haze (>90%), such that softening of white light from WLEDs was realized in 254 nm-driven UV-LED chips, corresponding white light with good color quality [Commission International de I’Eclairage coordinates, correlated color temperature, and color-rendering index of (0.34, 0.36), 5536 K and 86, respectively].

Coseismic offset is an important parameter to determine the characteristics of surface ruptures produced by large earthquakes and has significant implications for understanding fault-zone mechanics. To date, most studies have focused on broad-wavelength variations in coseismic offset and their related mechanisms. However, high-frequency variations in coseismic offset have been less commonly reported due to difficulty in field identification. Here, we show that three sites have typical abrupt changes in coseismic offset within short distances along surface ruptures produced by the 2008 Mw 7.9 Wenchuan earthquake. The Bailu, Qingping, and Xiaoyudong sites on different segments of the seismogenic faults show that coseismic vertical offsets can vary from ∼0.6 to ∼1.7 m at neighboring locations. Moreover, the offset gradients at the three sites are estimated from ∼2.5 to ∼30.9 m/km. Based on geologic and geophysical investigations at the three sites, we suggest that Quaternary deposits are the primary factor affecting coseismic offset. Specifically, thick and loosely packed deposits are more likely to yield smaller coseismic offsets than thin and densely packed deposits. Finally, through a compilation of recent thrust-type earthquakes, we suggest that the coseismic vertical offset gradient for thrust faults can vary greatly, which requires caution in seismic hazard assessments when designing linear infrastructure projects and constraining slip rates at specific sites.

A new porous metal–organic framework (MOF) {[Cd(Hbptc)]·H2O}n (Cdbptc) was assembled by Cd(II) ions and a rigid (1,1′-biphenyl)-2,4,6-tricarboxylic acid (H3bptc) ligand via a solvothermal method. C...

The two functional fluorinated ligands 2-fluoro-4-(1H-tetrazol-5-yl)benzoic acid (2-F-H2tzba) and 3-fluoro-4-(1H-tetrazol-5-yl)benzoic acid (3-F-H2tzba) were obtained by modifying 4-(1H-tetrazol-5-...

An unusual flower and tendril (uft) mutant in cucumber was caused by a mutation in Csa1G056950 encoding an F-box protein. Flowers and tendrils are important agronomic and yield traits of cucumber (Cucumis sativus L.). In this study, we identified an unusual flower and tendril (uft) mutant from an ethyl methanesulfonate (EMS) mutagenesis population. Genetic analysis revealed that the phenotype of the uft mutant was regulated by a single recessive nuclear gene. Map-based cloning and MutMap+ results demonstrated that Csa1G056950 (CsUFO), encoding an F-box protein, was the causal gene for the uft mutant phenotype of cucumber. A single nucleotide polymorphism (SNP) mutation (C to T) in the second exon of CsUFO resulted in premature translation termination. The expression level of CsUFO was significantly decreased in apical buds of the uft mutant compared with the wild-type (WT) WD1. Transcriptome analysis indicated that many genes for organ development were down-regulated in uft plants, suggesting CsUFO-associated networks that regulate flower and tendril development. These findings provide a new insight into understanding the molecular mechanisms of flower organogenesis in cucumber.

On the basis of an undeveloped asymmetrical pyridylcarboxylate ligand, 2-(2-carboxypyridin-4-yl)terephthalic acid (H3CPTA), an indium pyridylcarboxylate framework, [(Me)2NH2]1.5[In1.5(CPTA)2]·5.5NMF·6H2O (1), is synthesized under solvent thermal conditions. 1 displays a 3D anionic framework with a large void space, which contains open square channels with a cross section of 14.6 A and a pore surface decorated with carboxylic oxygen atoms. Depending on the anionic skeleton and high water stability, 1 exhibits high adsorption selectivity and capacity for cationic dyes in aqueous solution. Furthermore, the luminescence performance illustrates that 1 has selectivity and sensitivity to nitenpyram with good recyclability.

In recent years, breakthroughs in methods and data have enabled gravitational time delays to emerge as a very powerful tool to measure the Hubble constant $H_0$. However, published state-of-the-art analyses require of order 1 year of expert investigator time and up to a million hours of computing time per system. Furthermore, as precision improves, it is crucial to identify and mitigate systematic uncertainties. With this time delay lens modelling challenge we aim to assess the level of precision and accuracy of the modelling techniques that are currently fast enough to handle of order 50 lenses, via the blind analysis of simulated datasets. The results in Rung 1 and Rung 2 show that methods that use only the point source positions tend to have lower precision ($10 - 20\%$) while remaining accurate. In Rung 2, the methods that exploit the full information of the imaging and kinematic datasets can recover $H_0$ within the target accuracy ($ |A| < 2\%$) and precision ($< 6\%$ per system), even in the presence of poorly known point spread function and complex source morphology. A post-unblinding analysis of Rung 3 showed the numerical precision of the ray-traced cosmological simulations to be insufficient to test lens modelling methodology at the percent level, making the results difficult to interpret. A new challenge with improved simulations is needed to make further progress in the investigation of systematic uncertainties. For completeness, we present the Rung 3 results in an appendix, and use them to discuss various approaches to mitigating against similar subtle data generation effects in future blind challenges., 23 pages, 12 figures, 6 tables, MNRAS accepted

A bifunctional ligand strategy for modification of the functional pores is of great significance in the structural design of metal-organic frameworks (MOFs). Herein, a new 2-fold interpenetrated "pillared-layer" 3D Co-MOF, {[Co(HL)(4,4'-bipy)]·DMF·2H2O}n (1), was successfully synthesized by using two kinds of ligands, imidazolecarboxylic acid and pyridine. The metal-carboxylic layers are pillared by the 4,4'-bipy ligand, displaying a 3D framework with rectangular 3D channels (high BET surface of 190.9 m2 g-1 and maximum aperture of 3.9 A) that are decorated with abundant uncoordinated N and O atoms. 1 shows good water stability and thermal stability (320 °C). The proper pores and active sites endowed 1 with a selective adsorption of Congo red in aqueous solution. In addition, a high CO2 adsorption capacity and an excellent CO2 chemical conversion were observed.

Separation or purification is one of the difficult problems in the petrochemical industry. To help solve the difficulty of separation or purification for C2H2/CO2 and C2Hn/CH4 in the chemical industry, we synthesized a new metal-organic framework (MOF), [Ni(dpip)]·2.5DMF·H2O (1), by a bipyridyl-substituted isophthalic acid ligand. The MOF includes two types of one-dimensional (1D) tubular channels with different sizes and porous environments. The unique tubular channels lead to not only remarkable gas sorption capacity of C2H4, C2H2, and CO2, but also good selectivity for C2H2/CH4, C2H2/CH4, CO2/CH4, and C2H2/CO2, as demonstrated by single-component sorption isotherm results, ideal adsorbed solution theory calculations, and dynamic breakthrough curves. Grand canonical Monte Carlo (GCMC) simulation reveals preferential adsorption sites in the MOF for CO2, C2H2, and C2H4. The MOF also exhibits an obvious size-selective absorption effect on vapor molecules.

The chiral deformation of a conventional helical actuator is unidirectional in each activation (stimuli-on) process and in each recovery (stimuli-off) process, which means that the twisting direction remains the same regardless of the nature of deformation (either winding or unwinding or helix-inversion). In these cases, a complete stimuli-switching cycle is necessary for the realization of a bidirectional helical deformation process that comprises a reversal of twisting direction. Here, we achieved bidirectional and even multi-directional helical shape evolution in each stimuli-on (or off) process. The strategy relies on, on one hand, asymmetrically crosslinking and/or elongating the two sides of a photocrosslinkable liquid crystal polymer (LCP) monolith, and on the other hand, tailoring the uniaxially aligned polymer strip to form an off-axis mesogen orientation. We obtained a wide variety of helical actuators capable of reversing their twisting directions by only cooling (or heating). The mechanisms of these various chiral deformation-reversal behaviours and the two observed reversals of the twisting direction during cooling have been elucidated.

Developing highly efficient and low-cost electrocatalysts for the hydrogen evolution reaction (HER) in neutral media is crucial but still a significant challenge on account of the sluggish multistep reaction kinetics involved. Theoretically, constructing a metal/metal hydroxide interface with a metal hydroxide acting as a water dissociation promotor and a metal as the subsequent hydrogen adsorption site is expected to accelerate the HER kinetics in neutral media. We found that the intercalation of tungstate into Ni(OH)2 can tune the electronic structure of the Ni/Ni(OH)2 interface, decrease the energetic barrier for the Volmer step, and thus optimize the HER performance of Ni/Ni(OH)2 hybrid. Herein, a heterostructured Ni/Ni(OH)2 nanosheet array on Cu foam is designed and constructed via a simple hydrothermal and subsequent plasma reduction strategy. The HER performance can be further enhanced by assembling tungstate-intercalated Ni/Ni(OH)2 hybrid nanosheets on Cu2O nanotube arrays, exhibiting a low overpotential (39 mV @ 10 mA cm−2) and excellent stability (48 h).

Transition metal phosphides (TMPs) have been reported as efficient pre-catalysts for the oxygen evolution reaction (OER) in alkaline media. In situ generated metal oxyhydroxides on the surface of TMPs serve as real active sites. However, the reconstruction of most of the reported TMPs is incomplete and the active components cannot be fully used. Herein, hollow nanostructured Ni5P2/FeP4 nanoboxes (NiFeP NBs) are designed and synthesized as pre-catalysts. During the OER, the NiFeP NBs deeply reconstruct into low-crystalline and ultrathin NiOOH/FeOOH nanosheet assembled nanoboxes (NiOOH/FeOOH NBs). In situ Raman spectroscopy and ex situ characterization studies provide evidence that the hollow nanostructure facilitates the deep reconstruction of NiFeP NBs. Benefiting from the hierarchical hollow structure, the abundant interface between NiOOH and FeOOH, and plentiful defects, the reconstructed NiOOH/FeOOH NBs exhibit superior OER activity and excellent stability. Density functional theory (DFT) calculations reveal that the Fe–Ni dual sites in the NiOOH/FeOOH interface may be the possible active sites.

The downward continuation of potential fields is a process of calculating their values in a lower plane based on those of a certain plane. This technology is not only a data processing method for resource exploration but also plays an extremely important role in military applications. However, the downward continuation of potential fields is a typical linear inverse problem that is ill-posed. Generalized minimal residuals (GMRES) is an effective solution to ill-posed inverse problems, but it is unstable under the condition wherein the GMRES is directly applied in the calculation process. Moreover, the long-term behavior of its iterative computation is a disordered, divergent result. Therefore, to obtain stable solutions, GMRES is applied to solve the normal equations of the downward continuation of potential fields; it is also used to prequalify for occasional interruptions in the operation process by adding the damping coefficient, thus strengthening the stability conditions of the equations of residual minimization. Finally, the stable downward continuation of the potential fields method is proposed. As indicated by the theoretical data and the measured testing data, the method proposed in this paper has the advantages of high-precision and excellent stability. Furthermore, compared with the Tikhonov iteration method, the proposed method avoids the need to choose regularization parameters.

A new strategy incorporating three sequential treatments—selective molecular pre-masking, surface modification, and unmasking—is proposed for pore-size-dependent control of the surface properties of porous carbon materials. The method was experimentally validated using wide-pore-selective hydrophilization. n-Nonane was physically adsorbed for pre-masking, followed by room-temperature ozonation for surface modification. This process was used to introduce surface functional groups into wide pores, while leaving narrow pores intact. This study facilitates the development of new porous carbon materials with different surface properties that depend on pore size. This flexible strategy can be employed in conjunction with various molecular masking agents and surface-modification methods.

By using the generating tree technique and the obstinate kernel method, Kim and Lin confirmed a conjecture due to Martinez and Savage which asserts that inversion sequences e = ( e 1 , e 2 , … , e n ) containing no three indices i j k such that e i ≥ e j , e j ≥ e k and e i > e k are counted by Baxter numbers. In this paper, we provide a bijective proof of this conjecture via an intermediate structure of open partition diagrams, in answer to a problem posed by Beaton-Bouvel-Guerrini-Rinaldi. Moreover, we show that two new classes of pattern-avoiding inversion sequences are also counted by Baxter numbers.

To help address efficient separation of CH light hydrocarbons and CH/CO in the chemical industry, the self-assembly via an azolate-carboxylate ligand and Co(II) ion gave rise to a new porous MOF material, [Co(btzip)(Hbtzip)]·2DMF·2HO () (Hbtzip = 4,6-bis(triazol-1-yl)isophthalic acid). In the MOF, the pores are modified by rich uncoordinated triazolyl Lewis basic N atoms and acidic -COOH groups, which strengthen interactions with CH hydrocarbons and CO molecules, leading to high adsorption amounts for CH CH, CH, and CO and remarkable separation efficiency for CH-CH, CO-CH, and CH-CO mixtures, as confirmed by breakthrough experiments on the realistic gas mixtures. The MOF also reveals outstanding selective adsorption ability for benzene/toluene, methanol/1-propanol, methanol/2-propanol, and 2-propanol/1-propanol isomers. Molecular simulations disclose the different adsorption sites in the MOF for various adsorbates.

Tuning the emissive color changes of lanthanide (Ln) complexes is an important and appealing project for promoting the applications of Ln-complexes. A solvothermal reaction of 4-cyano-3-methylbenzoic acid (HL) and Ln(NO3)3·6H2O affords three isostructural Ln-complexes [Eu(L)3(H2O)2]n (1-Ln) (Ln = Eu, Gd and Tb) with one-dimensional chain structures. 1-Eu and 1-Tb show bright red and green emissions with absolute quantum yields of 3.06% and 11.96%, respectively, and the energy transfer was analyzed in detail through combined calculations. Interestingly, a series of heterometallic doped 1-TbxEu1-x coordination polymers were also obtained by mixing different ratios of Eu3+ and Tb3+ ions, which possess continuous luminescent color changes from green to yellow, orange and red. In addition, 1-Eu exhibits high quenching efficiency and low detection limit (∼10-4 M) for the simultaneous sensing of MnO4-, CrO42- and Cr2O72- ions in water.

Herein, the synthesis of borodepsipeptides utilizing boron-containing isocyanides is described. The target compounds were synthesized via Passerini three-component reaction (P-3CR), in which H2O was utilized as the solvent. Further, unlike conventional P-3CR, where Lewis acid catalysts are often required, the reported method requires no catalyst and proceeds in room temperature. A variety of aldehydes and acids were used as the building blocks to generate the desired products.

Three-dimensional (3D) triply interlocked catenanes are a family of chemical topologies that consist of two identical, mechanically interlocked coordination cage components with intriguingly complex structures. Although only a few successful constructions of 3D interlocked catenanes have been achieved to date via metal-mediated assembly, these complex structures have thus far only been targeted by metal-nitrogen/oxygen coordination techniques. Here, taking advantage of rational ligand design, we report the efficient construction of a series of 3D triply interlocked [2]catenanes of the formula [Ag3L2]2, wherein the metal ions exclusively form bonds to N-heterocyclic carbene (NHC) units, and their subsequent transmetalation to the corresponding [Au3L2]2 gold analogues. The formation and transmetalation reactions proceed under mild conditions and are generally applicable. A series of characterization techniques were applied to confirm the formation and structure of the desired 3D triply interlocked architectures: multinuclear NMR spectroscopy, ESI-MS, and single-crystal X-ray diffraction analysis. The solid-state structure of [Ag3(1a)2]2(PF6)6 unambiguously confirms the existence of a 3D catenane that consists of two identical, mechanically interlocked trinuclear hexacarbene cage components. The interlocking of two 3D cages into a [2]catenane is driven by the efficient π···π stacking of triazine-triazine stacks with cooperative interactions between imidazo[1,5-a]pyridine subunits. Notably, the triply interlocked organometallic cages exhibit good stability toward various organic solvents, concentrations, and temperatures, and no disassembly occurred in the presence of coronene or pyrene. The future construction of mechanically interlocked architectures using metal-carbene bonds rather than metal-nitrogen bonds may provide assemblies with interesting properties for as-yet-unimagined applications in fields such as sensors and molecular electrical conductors.

The efficient backbone-directed self-assembly of cyclic metalla[3]catenanes by the combination of tetrachloroperylenediimide (TCPDI)-based dinuclear rhodium(III) clips and 4,4'-diazopyridine or 4,4'-dipyridylethylene ligands is realized in a single-step strategy. The topology and coordination geometry of the cyclic metalla[3]catenanes are characterized by NMR spectroscopy, ESI-TOF-MS spectrometry, UV/Vis-NIR spectroscopy, and X-ray diffraction studies. The most remarkable feature of the formed cyclic metalla[3]catenane is that it contains π-aggregates (ca. 2.6 nm) incorporating six TCPDIs. Further studies revealed that cyclic metalla[3]catenanes can be converted reversibly to their corresponding sodium adducts and precursor building blocks, respectively. This strategy opens the possibility of generating unique supramolecular structures from discrete functional π-aggregates with precise arrangements.

Simultaneous attainments of high conductivity and superior catalysis are major challenges for amorphous electrocatalysts in carbon dioxide electroreduction at high overpotential. In this study, one protocol is first demonstrated to drive the shell amorphization of nanoporous Ag-Bi (a-NPSB) catalyst with the spatially interconnected ligament during the initial stage of CO2ER. This newborn a-NPSB bestows the outstanding catalysis, evidenced by a Faradaic efficiency of 88.4% for formate production at -1.15 V vs RHE, specific current density of 21.2 mA cm-2, and mass specific current density of 321 mA mg-1. The unique catalysis is considered as the collective contribution of the conductive ligament internally and amorphous Bi2O3 shell with about 3.2 nm thickness externally. Simultaneous obtaining of the conductivity of inner metals and catalytic activity of the amorphous shell will pave a new avenue for designing a robust electrode during electrochemical reaction.

Utilizing 5,5′-oxidiisophthalic acid (H4odip) ligand, one 3D framework {[Ni2(odip)(H2O)4(DMF)]·DMF·2H2O}n (1) with a rare 3-nodal (3,3,4)-connected topological net based on two types of Ni12(odip)1...

The first isolable silylene-germylene complex 5 was assembled by a salt metathesis reaction between the germylene anion 3 and the N-heterocyclic chlorosilylene 4, and structurally characterized. The central structure of 5 demonstrates a remarkable gauche-bent geometry with the silylene and germylene units, which are interconnected by a Si-Ge bond with a length of 2.4498(9) A. This value is not only perceptibly longer than the distances known in doubly bonded germasilenes, and also slightly longer than those in germylsilanes. The DFT calculations on 5 confirmed a nearly nonpolar SiI -GeI single-bond nature and its bonding orbital, as well as the aromaticity of the C3 NGe-rings in 3 and 5. The latter increases the molecular stability of 3 and 5, and makes the preparation of silylene-germylene complex 5 a reality.

This work explores mechanical properties, structural evolution, and mechanism of creep-life enhancement for widely used P9 heat-resistant steel. The 17-year-on-site used P9 alloy exhibit a higher tensile strength and a smaller elongation than the new P9 alloy from room temperature to 700 °C. The P9 alloy also displays a typical ductile feature with a significantly necking profile. The P9 alloy shows phase transformation sequences of α-Fe (bcc) → A c 1 ∼ 858 ° C α + γ -Fe (bcc + fcc) → A c 3 ∼ 894 ° C γ-Fe (fcc) upon heating and γ-Fe (fcc) → M s ∼ 352 ° C martensite (bct) → M f ∼ 300 ° C martensite (bct) upon cooling. The new P9-alloy tube mainly contains ∼73.5% ferrite phase (α-Fe) and ∼26.5% carbide M3C. However, the used P9-alloy tube shows four crystalline phases including ∼45.9% ferrite, ∼14.5% martensite, ∼37.5% cementite (M3C) and ∼2.7% carbide M23C6. The creep test indicates that the used P9-alloy tube has a longer creep-life (or better anti-creep ability) than the new tube. Activation energies of atomic diffusion for the new and used tubes are respectively 252.45 and 345.87 kJ/mol, indicating a decreased diffusion capability in the used tube. This work suggests that martensite laths, lath boundaries, and precipitates (such as carbides) play important roles to inhibit creep-deformation in the P9-alloy steel.

With the rapid increase in service requirements driven by Internet of Things (IoT) networks, mobile crowdsourcing has become a compelling paradigm that can efficiently solve complex tasks in the physical world. Nevertheless, we found that most IoT tasks have constraints on deadline, location, and resource consumption, which limit the application of crowdsourcing platforms in the IoT networks. In this article, we innovatively propose a reliable fog-based temporal–spatial crowdsourcing for serving the above tasks. In this scenario, the key point is to achieve the best match of the attributes among tasks, fog nodes, and workers. As the bridge of the other two parts, fog nodes determine the orientation of tasks. Therefore, we present a temporal–spatial task allocation (TS-TA) scheme in the fog layer, aiming to make task results more reliable. In this scheme, we build a temporal–spatial attribute learning model based on the user behaviors. Then, we use the users’ interest attribute matching model to identify the candidate fog nodes that satisfy the requirements of temporal–spatial tasks. We choose the fog nodes with low spatial correlation that is benefit to defense the attack on the nodes in the intensive area. Meanwhile, we assign the redundancy nodes for intrusion response through replacing the attacked/negative node. Both theoretical and real-topology simulation results validate that the proposed scheme can get better performance in system resource consumption and system robustness compared with other benchmark schemes.

We construct a new scheme whose primary unknowns include both cell-centered unknowns and edge unknowns on discontinuous line to solve diffusion equations with discontinuous coefficient. First, two linear fluxes are given on both sides of the cell edge, respectively. In order to deal with the defect of the existing scheme preserving maximum principle for solving diffusion problem with discontinuous coefficient, in addition to cell-centered unknowns, we also introduce cell-edge unknowns on discontinuous line as basic unknowns. Second, the conservative flux is constructed by using nonlinear weighted combination of these two linear fluxes. For the cell-edge unknowns on discontinuous line, we add an equation by using the continuity of normal flux. Compared to the classical cell-centered nonlinear finite volume scheme, the introduction of cell-edge unknowns on discontinuous edge is the key point for our scheme to solve diffusion equations with discontinuous coefficient. Then we prove that the scheme satisfies the discrete maximum principle. Based on this, the existence of a solution for the scheme is also obtained. Numerical results are presented to show that our scheme obtains almost second order accuracy for solution on random meshes, preserves discrete maximum principle, and is superior to the existing scheme (in Sheng and Yuan (2011)) preserving the maximum principle on dealing with the problems with strong anisotropic discontinuous coefficient on distorted meshes.

Electrochemical carbon dioxide reduction meditated by metallic catalysts suffers from restricted selectivity and competition from hydrogen evolution, which sensitively depends on ambiguous contributions of alloying and strain state in bimetallic catalysts. Herein, nanoporous Au-Sn (NPAS) containing trace tin solute in Au lattices is delicately designed to convince real strain effect, while eliminating other undesirable factors, such as alloying, crystal facets and surface composition. Compared with nanoporous gold (NPG), the NPAS with a solute strain of ∼2.2 % enables more efficient CO2-to−CO conversion, with an efficiency as high as 92 % at -0.85 V versus reversible hydrogen electrode (vs. RHE), and the high activity can retain for more than 8 h. The combination of HRTEM and surface valence band photoemission spectra reveals that the tensile strain on the surface of 3D nanoporous structure promotes the catalytic activity by shifting up the d-band center and strengthening the adsorption of key intermediate *COOH. A small amount of Sn solute in the nanoporous alloy can prevent ligament coarsening effectively and improve the electrochemical stability.

With the aid of a pyridyl tetracarboxylate ligand, 2,5-bis(2',5'-dicarboxylphenyl)pyridine (H4L), two indium-organic frameworks, [In2(L)(OH)2]·2DMF·2H2O (1) and [Me2NH2][In(L)]·2.5NMF·4H2O (2), with (6,8)- and (4,4)-connected nets have been constructed in different solvent systems. Both 1 and 2 exhibit high thermal and chemical stability. Gas sorption behavior of 1 and 2 for N2, C2H2, C2H4, CO2, and CH4 indicate excellent separation selectivities of C2Hx/CH4 and CO2/CH4. Furthermore, 1 possesses a high density of Bronsted sites and shows efficient catalytic conversion for CO2 cycloaddition with epoxides. Meanwhile, luminescence investigations reveal that 2 can detect nitrofurazone efficiently.

The oxidation behavior of a newly designed Co–Ni-based alloy with varied addition of Ti (1.4 and 2.1 wt.%, hereafter referred as 1.4Ti and 2.1Ti alloys) was explored in air at 900 °C. It is found that an outer oxide layer composed of CoO, an intermediate oxide layer composed of intermittent TiO2 plus continuous Cr, W-rich oxides, and an inner oxidized region composed of Al2O3 were formed on the surface of 1.4Ti alloy, whereas the oxide structure of 2.1Ti alloy was composed of CoO as the outer oxide layer, continuous TiO2, Cr2O3, and WO3 as intermediate oxide layer, and Al2O3 as the inner oxidized region. With increasing Ti content, continuous TiO2 films formed in the intermediate oxide layer, which would lead to the formation of compact Cr2O3 and improved oxidation resistance after 100 h oxidation at 900 °C. These observations indicated that Ti addition can improve the high-temperature oxidation resistance of Co–Ni-based alloys.

The coordination preference of different metal ions and ligands have an immense influence on the constructions of functional MOF materials. In this work, two new monometallic complexes, namely [Ag(HL)(bipy)0.5 ] (1) and {[Tb(L)1.5 (H2 O)]⋅4 H2 O}n (2) (bipy=4,4-bipyridine), have been synthesized successfully by employing a bifunctional 2-(imidazol-1-yl)terephthalic acid (H2 L) ligand. After that, two new different heterometallic-organic frameworks (HMOFs), namely {[TbAg(L)2 (H2 O)3 ]⋅H2 O}n (3) and [TbAg(L)2 (H2 O)]n (4), were obtained from complexes 1 and 2 as the precursors based on a rational stepwise construction strategy and the theory of hard and soft acids and bases (HSAB principle), respectively. The HMOFs bearing dual metallic catalytic sites (Tb and Ag) can be used as heterogeneous catalysts without losing performance for the chemical fixation of CO2 with epoxides including the sterically hindered epoxides, demonstrating some of the highest reported catalytic activity values. This work may provide a new synthetic route toward tailoring new HMOFs with excellent catalytic activity.

Metal-organic frameworks (MOFs) with zeolitic structure process fantastic structural metrics and display excellent applications in many aspects; however, they are difficult to assemble. Herein, on the basis of a tetrahedral Zn

Novel main-chain liquid crystalline Diels-Alder dynamic networks (LCDANs) were prepared that exhibit unprecedented ease for actuator programming and reprocessing compared to existing liquid crystalline network (LCN) systems. Following cooling from 125 °C, LCDANs are deformed with aligned mesogens self-locked at room temperature by slowly formed Diels-Alder (DA) bonds, which allows for the formation of solid 3D actuators capable of reversible shape change, and strip walker and wheel-capable light-driven locomotion upon either thermally or optically induced order-disorder phase transition. Any actuator can readily be erased at 125 °C and reprogrammed into a new one under ambient conditions. Moreover, LCDANs can be processed directly from melt (for example, fiber drawing) and from solution (for example, casting tubular actuators), which cannot be achieved with LCNs using exchangeable covalent bonds. The combined attributes of LCDANs offer significant progress toward developing easily programmable/processable LCN actuators.

Based on the mixed carboxylate ligands synthesis strategy, an indium-organic framework, (Me2NH2)1.5[In1.5(FBDC)(BDC)]·2.5NMF·CH3CN (1) has been constructed by using the mixed (2,5-di(2',5'-dicarboxylphenyl)-difluorobenzene (H4FBDC) and terephthalic acid (H2BDC). Compound 1 contains a 3D intersecting pore system which surface is modified by F atoms, and it has excellent stability in pH = 2-12 aqueous solutions. The activated 1 shows high separation for C2H2/CO2 and C2H2/CH4. Moreover, 1 not only has strong luminescence but also has the high selectivity and sensibility of fluorescence detection to nitrofurazone (NZF) in antibiotic sensing experiments, which can be used as a luminescence sensor for NZF detection.

Three new pairs of 2-fold interpenetrated and self-entangled three-dimensional isostructural porous metal-organic frameworks (MOFs), [Zn(L1)(x)0.5]·0.5H2O (x = bipy for 1, bpa for 2, and bpe for 3) and [Zn(L2)(x)0.5]·0.5H2O (x = bipy for 4, bpa for 5, and bpe for 6) [bipy = 4,4'-bipyridine, bpa = 1,2-bis(4-pyridyl)ethylene, and bpe = 1,2-bis(4-pyridyl)ethylene], have been created and fine-tuned via similar skeleton ligands 2-(imidazol-1-yl)terephthalic acid (H2L1) and 2-(1H-1,2,4-triazol-1-yl)terephthalic acid (H2L2) and N-auxiliary coligands with different linking groups. Interestingly, the porosities of the MOFs can be effectively increased via the insertion of -CH2CH2- or -CH═CH- spacers into the N-auxiliary bipy ligand. As a result, complexes 5 and 6 displayed highly enhanced CO2 uptake capacities. Furthermore, complex 5 also had a higher C2/C1 selectivity as well as great CO2 cycloaddition efficiency.

Palladium-catalyzed alkene-directed cross-coupling of aryl iodide with another aryl halide through C-H arylation opens a unique avenue for unsymmetrical biaryl-derived molecules. However, homo-coupling of aryl iodides often erodes the overall synthetic efficiency. Reported herein is a highly chemoselective Pd0 -catalyzed alkyne-directed cross-coupling of aryl iodides with bromophenols, which was subsequently followed by phenol dearomatization to furnish a very attractive [2+2+1] spiroannulation. Notably, possible homo-coupling of aryl iodides was not observed at all. Mechanistic studies indicated that a five-membered aryl/vinyl palladacycle most likely accounts for promoting the key step of biaryl cross-coupling.

The development of appropriate catalysts with relatively low cost, good selectivity and excellent stability is one of the major issues in electrochemical reduction of CO2. In this work, an efficient electrocatalyst was fabricated via ultra-small Co3O4 nanoparticles encapsulated within the tip of carbon nanotubes, denoted as Co/CNTs. Benefiting from the synergistic effects of highly active Co3O4 nanoparticles and well-graphitized carbon nanotubes, Co/CNTs exhibited remarkable performance in CO2 electroreduction. In a conventional H-type cell, CO with a 90% faradaic efficiency and 20.6 mA cm−2 partial current density was obtained at only −0.7 VRHE cathode potential with 40 hour stability. Upon switching to a gas-diffusion device, the CO partial current density could reach as high as 232.6 mA cm−2 with >80% faradaic efficiency, which might be even comparable to that of state-of-the-art CO2 electrocatalysts. Our work could also provide a new strategy for developing non-noble metal catalysts for CO2 electroreduction.

Extrusion temperature can significantly influence grain size, the shape of second phase particles and the dislocation distribution of Mg alloys. In this study, the effects of extrusion temperatures ranging from 250 to 400 °C on the microstructure, mechanical properties and corrosion resistance of a Mg-Al-Ca alloy with 1.61 wt.% Al and 1.76 wt.% Ca (Mg-1.61Al-1.76Ca) were investigated. The results showed that the size of grains and phases increased with an increase in extrusion temperature; the yield strength and ultimate tensile strength values decreased with an increase in temperature, while the fracture elongation increased initially (up to 300 °C) and decreased thereafter with an increase in temperature. Under test, the extruded alloy exhibited some evidence of corrosion at 250 °C, while extrusion at 300 °C demonstrated better corrosion resistance. Thus, the 300 °C extruded alloy possessed the optimum comprehensive performance because of the relatively small grains, fine second phase particles and fewer dislocations.

Carbon dioxide electroreduction provides a useful source of carbon monoxide, but comparatively few catalysts could be sustained at current densities of industry level. Herein, we construct a high-yield, flexible and self-supported single-atom nickel-decorated porous carbon membrane catalyst. This membrane possesses interconnected nanofibers and hierarchical pores, affording abundant effective nickel single atoms that participate in carbon dioxide reduction. Moreover, the excellent mechanical strength and well-distributed nickel atoms of this membrane combines gas-diffusion and catalyst layers into one architecture. This integrated membrane could be directly used as a gas diffusion electrode to establish an extremely stable three-phase interface for high-performance carbon dioxide electroreduction, producing carbon monoxide with a 308.4 mA cm−2 partial current density and 88% Faradaic efficiency for up to 120 h. We hope this work will provide guidance for the design and application of carbon dioxide electro-catalysts at the potential industrial scale., Here the authors deploy Ni single atom-decorated carbon membranes as integrated gas diffusion electrodes to construct an extremely stable three-phase interface for CO2 electroreduction, producing CO with a partial current density of 308.4 mA cm–2 and a Faradaic efficiency of 88% for up to 120 h.

Utilizing the self-assembly strategy between the paddle-wheel Cu2(COO)4 cluster and a terephthalic acid ligand modified by a triazolyl group, namely H2tztp = 2-(1H-1,2,4-triazol-1-yl)terephthalic acid, a porous MOF, [Cu0.5(tztp)0.5]·0.5DMA (1), has been successfully designed and built. 1 is a three-dimensional self-interpenerated framework with a (3,6)-connected rtl topology, and contains hydrophilic and hydrophobic channels decorated with rich uncoordinated triazolyl N atoms and benzene rings from tztp ligands, respectively. The unique porous environment leads not only to high gas adsorption amounts of CO2, C2H6, C2H4 and C2H2 but also to a good separation ability of C2 hydrocarbons over CH4, CO2 over CH4, and C2H2 over CO2 in the MOF. The specific adsorption sites of CO2 and C2 hydrocarbons were explored by a molecular simulation. The breakthrough experiments demonstrated excellent dynamic separations for CO2 and CH4, C2 hydrocarbons and CH4 as well as C2H2 over CO2. The MOF also revealed excellent adsorption and separation ability for CH3OH over other bulkier alcohol molecules.

Three new isostructural 3D lanthanide metal-organic frameworks (Ln-MOFs), {H[LnL(H2 O)]⋅2 H2 O}n (1-Ln) (Ln=Eu3+ , Gd3+ and Tb3+ ), based on infinite lanthanide-carboxylate chains were constructed by employing an ether-separated 5,5'-oxydiisophthalic acid (H4 L) ligand under solvothermal reaction. 1-Eu and 1-Tb exhibit strong red and green emission, respectively, through the antenna effect, as demonstrated through a combination of calculation and experimental results. Moreover, a series of dichromatic doped 1-Eux Tby MOFs were fabricated by introducing different concentrations of Eu3+ and Tb3+ ions, and they display an unusual variation of luminescent colors from green, yellow, orange to red. 1-Eu with channels decorated by ether O atoms and the open metal sites displays good performance for CO2 capture and conversion between CO2 and epoxides into cyclic carbonates.

Herein, a new porous Zn(II)-based metal-organic framework (MOF 1) has been prepared, the structure of which featured a twofold entangled motif based on two typical secondary building units (SBUs). The gas sorption studies indicated that MOF 1 may be explored as a useful platform to encapsulate metallic nanoparticles. Then the Au@1 composite has been prepared via a facile incorporation method without extra reducing agents. The Au@1 composite has been fully characterized by HRTEM, SEM-EDX, PXRD, gas sorption, XPS, ICP, etc. Catalytic experiments showed that the Au@1 composite had a perfect catalytic performance in CO2 fixation for epoxides with different substituents under mild conditions.

The first isolable Ge5-spiropentadiene 1 was synthesized via the reduction of (iPr3Si)2NGeCl (3) with potassium. The crystal structure of 1 reveals a spirocyclic Ge5 skeleton containing two Ge-Ge double bonds (avg. 2.34 A), which are fettered in two Ge3 rings with a dihedral angle of 70.193°. The DFT calculations and orbital analysis show that the σ-delocalization of the Ge5 skeleton and the 2π-delocalized aromatic Ge3 rings enhance the stability of molecule 1.

A doubly interpenetrated metal–organic framework (MOF) [Zn4(L)3O]·8DMF·H2O (1, DMF = N,N-dimethylformamide) including the [Zn4O] clusters was first synthesized by employing a rigid 2,6-bis(4′-carbo...

Vegetables are an ideal source of human Se intake; it is important to understand selenium (Se) speciation in plants due to the distinct biological functions of selenocompounds. In this hydroponic study, the accumulation and assimilation of selenite and selenate in pak choi (Brassica rapa), a vastly consumed vegetable, were investigated at 1-168 h with HPLC speciation and RNA-sequencing. The results showed that the Se content in shoots and Se translocation factors with selenate addition were at least 10.81 and 11.62 times, respectively, higher than those with selenite addition. Selenite and selenate up-regulated the expression of SULT1;1 and PHT1;2 in roots by over 240% and 400%, respectively. Selenite addition always led to higher proportions of seleno-amino acids, while SeO42- was dominant under selenate addition (>49% of all Se species in shoots). However, in roots, SeO42- proportions declined substantially by 51% with a significant increase of selenomethionine proportions (63%) from 1 to 168 h. Moreover, with enhanced transcript of methionine gamma-lyase (60% of up-regulation compared to the control) plus high levels of methylselenium in shoots (approximately 70% of all Se species), almost 40% of Se was lost during the exposure under the selenite treatment. This work provides evidence that pak choi can rapidly transform selenite to methylselenium, and it is promising to use the plant for Se biofortification.

Focus is on efficient estimation of a dynamic space–time panel data model that incorporates spatial dependence, temporal dependence, as well as space–time covariance and can be implemented where there are a large number of spatial units and time periods. Quasi-maximum likelihood (QML) estimation in cases involving large samples poses computational challenges because optimizing the (log) likelihood requires: (1) evaluating the log-determinant of a large matrix that appears in the likelihood, (2) imposing stability restrictions on parameters reflecting space–time dynamics, and (3) simulations to produce an empirical distribution of the partial derivatives used to interpret model estimates that require numerous inversions of large matrices. A Markov Chain Monte Carlo (MCMC) estimation procedure is set forth that produces estimates equivalent to those from QML along with a Monte Carlo integrated estimate of the log-marginal likelihood, useful for model comparison. An applied illustration is based on over six million observations. The MCMC estimation procedure uses: (1) a Taylor series approximation to the log-determinant based on traces of matrix products calculated prior to MCMC sampling, (2) block sampling of the spatiotemporal parameters, which allows imposition of the stability restrictions, and (3) a Metropolis–Hastings guided Monte Carlo integration of the log-marginal likelihood. In addition, an efficient approach to simulations needed to produce the empirical distribution of the partial derivatives for model interpretation is set forth.

The main avenue in which antibiotic resistance enters soils is through the application of livestock manure. However, whether antibiotic resistant bacteria (ARB) and antibiotic resistance genes (ARGs) persist and spread to vegetables with the application of manure and manure products is still unclear. This study assessed seven kinds of cultured ARB, 221 ARGs subtypes and three transposon genes in the vegetable production chain (from manure to biocompost, soils and vegetables). Results showed that at least 80% of ARB, ARGs and transposon genes were removed after aerobic composting. However, aerobic composting did not reduce the diversity of ARGs in pig and chicken manure. A total of 19 ARGs subtypes still persisted during aerobic composting. Compared to the temperature-thermophilic stage, the number of bacteria resistant to erythromycin, the relative abundance of ARGs and IS613 increased 1.7-4.9 times at the temperature-decreasing stage. Direct application of biocompost introduced 11 ARGs subtypes to pakchoi, but these ARGs did not present in biocompost-amended soil. A transposon gene tnpA was also detected in the biocompost-amended soil, but surprisingly was found in the control vegetable. This demonstrated that the transposon gene is intrinsic in pakchoi. Bacterial community analysis and network analysis revealed that a specific genus Terrisporobacter carrying tetO, tetW ermB and tnpA persisted in the vegetable production chain, which may generate a potential risk in the following production. Our study illuminates the persistence and spreading of antibiotic resistance in the vegetable production chain which could help manage the ecological risks arising from antibiotic resistance in manure sources.