Search

Low-cost and efficient bifunctional catalysts are urgently needed for overall water splitting used in large-scale energy storage. In this study, we develop a nickel and iron (di)sulfide (Ni-Fe-S) composite catalyst that is in situ synthesized and fixed within the intergranular nanopores inside high pure polycrystalline graphite. Two precursor solutions (reactants) may permeate the graphite intergranular pores to a depth of more than 3.5 mm. The nanoscale pores serve as an array of nanoreactors for the synthesis of the Ni-Fe-S nanoparticles under conditions much milder than usual. The prepared catalyst efficiently catalyzes both the hydrogen and oxygen evolution reactions (HER and OER) in 1.0 M KOH. It delivers a current density of 400 mA cm-2 at a full cell voltage of around 2.3 V without considerable activity decay over 24 h electrolysis. The active species of the catalyst are different for the HER and OER and discussed accordingly. The synthesis strategy based on the nanopores in a monolithic conductive substrate proves to be a simple, efficient, and promising way to prepare electrocatalysts that are cheap, abundant, and industrially attractive.

A metal- and base-free C(sp2)-H direct arylsulfonylation of secondary and tertiary enamides with aryldiazonium salts and ex situ generated SO2 (from SOgen) is presented. This method runs smoothly to produce β-amidovinyl sulfones with excellent stereoselectivities in moderate to excellent yields. Moreover, this strategy features good functional group tolerance and environmentally benign reaction conditions. Mechanistic experiments indicate that this sulfonylation may proceed in a radical pathway.

GRO J1008-57, as a Be/X-ray transient pulsar, is considered to have the highest magnetic field in known neutron star X-ray binary systems. Observational data of the X-ray outbursts in GRO J1008-57 from 2017 to 2020 were collected by the Insight-HXMT satellite. In this work, the spin period of the neutron star in GRO J1008-57 was determined to be about 93.28 seconds in August 2017, 93.22 seconds in February 2018, 93.25 seconds in June 2019 and 93.14 seconds in June 2020. GRO J1008-57 evolved in the spin-up process with a mean rate of − ( 2.10 ± 0.05 ) × 10−4 s/d from 2009 – 2018, and turned into a spin down process with a rate of ( 6.7 ± 0.6 ) × 10−5 s/d from Feb 2018 to June 2019. During the type II outburst of 2020, GRO J1008-57 had the spin-up torque again. During the torque reversals, the pulse profiles and continuum X-ray spectra did not change significantly, and the cyclotron resonant scattering feature around 80 keV was only detected during the outbursts in 2017 and 2020. Based on the observed mean spin-up rate, we estimated the inner accretion disk radius in GRO J1008-57 (about 1 - 2 times of the Alfven radius) by comparing different accretion torque models of magnetic neutron stars. During the spin-down process, the magnetic torque should dominate over the matter accreting inflow torque, and we constrained the surface dipole magnetic field B ≥ 6 × 10 12 G for the neutron star in GRO J1008-57, which is consistent with the magnetic field strength obtained by cyclotron line centroid energy.

This study aimed to explore the phytoremediation potential of Salvia tiliifolia for cadmium (Cd)-contaminated soils and to understand the interactions in soil-Cd-plant systems. We assessed the Cd tolerance and accumulation characteristics of S. tiliifolia grown in soils with 0, 5, 25, and 50 mg kg− 1 Cd for 3 months. We also analysed the changes in physicochemical properties, enzyme activities, and bacterial community composition in the rhizosphere soils of S. tiliifolia. S. tiliifolia could tolerate all Cd concentrations with unchanged biomass. Cd concentrations (21.50–189.50 mg kg− 1) in roots of S. tiliifolia and corresponding bioconcentration factors (3.79–4.30) were much higher than those in shoots, and Cd translocation factors (0.03–0.23) were thereby very low. Rhizosphere pH decreased with increasing concentrations of Cd. Soil pH and rich organic matter may jointly affect the soil available Cd. Ultimately, soil enzyme activities involved in carbon, nitrogen, and phosphorus cycles were affected to varying degrees, and bacterial diversity and richness were slightly influenced by Cd stress. Interestingly, bacterial ABC transporters were induced by Cd stress during this process. S. tiliifolia can be designed as a Cd excluder. The induced soil bacterial ABC transporters may contribute to Cd detoxification and accumulation in both soil microbial communities and S. tiliifolia plants.

This special issue starts with an article on high seismicity detection, namely “Fluid-Induced High Seismicity in Songliao Basin of China,” co-authored by Sheng et al. (2020). The authors attempt to...

In continuation of our efforts toward the discovery of potent HIV-1 NNRTIs with diverse structures, a series of novel S-DACO analogues of 6-(2-cyclohexyl-1-alkyl)-2-(2-oxo-2-phenyl-ethylsulfanyl)pyrimidin-4(3H)-ones were designed, synthesized and evaluated for their antiviral activities in MT-4 cells. Most of these new compounds showed moderate to good activities against wild type HIV-1 with IC50 values ranging from 7.55 μmol/L to 0.018 μmol/L. Among them, compound 5c was identified as the most promising inhibitor against HIV-1 replication with an IC50 = 0.018 μmol/L, CC50 = 194 μmol/L, and SI = 12791, which was much more potent than the reference drugs NVP and DLV and comparable to AZT and EFV. In addition, 5c also exhibited improved activity against double mutant HIV-1 strain RES056 compared to that of the reference drugs NVP/DLV and DB02. The preliminary structure-activity relationship (SAR) and molecular modeling studies were also discussed, which provides some useful indications for guiding the further rational design of new S-DACO analogues. keywords: NNRTIs, -DABOs, -DACOs, Anti HIV-1 activity, SAR ispartof: Chinese Chemical Letters vol:32 issue:3 pages:1020-1024 status: published

Three new compounds, including 6-methoxy-3,4,5,7-tetramethylisochromane-3,8-diol (1), 3,4,5,7-tetramethylisochromane-3,6,8-triol (2), streptimidone derivative (3), along with ten known compounds (4-13) were isolated from the Streptomyces morookaensis strain Sm4-1986. Their chemical structures were established based on the information from UV, IR, NMR (1H NMR, 13C NMR, 1H-1H COSY, HSQC, HMBC, NOESY), and mass spectroscopic. Moreover, all the isolated new compounds were evaluated for antibacterial activities (S. aureus, B. cereus, S. epidermids and methicillin-resistant S. aureus) and their cytotoxicities against MCF-7, A549, Hela tumor cell lines and Marc-145 normal cell line.

In this paper, we are concerned with the boundedness of all solutions of the asymmetric oscillation x ″ + a x + − b x − = p ( t ) , where x + = max ⁡ { x , 0 } , x − = max ⁡ { − x , 0 } , p ( t ) is a real analytic 2π periodic function, a and b are two different positive constants satisfying ω 0 : = 1 2 ( 1 a + 1 b ) ∈ R \ Q and the condition | k ω 0 − l | ≥ c 0 Ω ( | k | ) , k ∈ Z \ { 0 } , l ∈ Z , where Ω is an approximation function and c 0 is a small positive constant. In particular, when a = 5 , b = 1 , p ( t ) = cos ⁡ 4 t , the boundedness of all solutions will be proved.

Bulk and interfacial nonradiative recombination hinder the further enhancement of the power conversion efficiency (PCE) and stability of SnO2-based planar perovskite solar cells (PSCs). To date, it is still a huge challenge to minimize the bulk and interfacial nonradiative recombination losses, and thus maximize the potentials of PCE and stability. Herein, a novel and effective multifunctional modification strategy through incorporating Girard's Reagent T (GRT) molecules with multiple functional groups to modify SnO2 nanoparticles (NPs), which significantly reduces the bulk and interfacial nonradiative recombination losses through the simultaneous achievement of suppressing nanoparticle agglomeration, improving the electronic property of SnO2 films, facilitating the vertical growth and enlarging the grain size of perovskite crystals, and passivating interfacial defects is reported. As a result, the device based on GRT modification delivers a much higher PCE of 21.63%, along with significantly suppressed hysteresis, as compared to the control device (19.77%). The device stability is ameliorated after GRT modification. The unencapsulated device with GRT maintains 99.5% of its initial PCE after aging at 60 °C for 720 h and 58.5% after illumination for 672 h under one sun, respectively. The present work provides guidance for the design of multifunctional modification molecules toward efficient and stable PSCs.

As a promising way to modulate the photoluminescence properties and stability of perovskites and perovskite variants, doping has attracted wide attention in the field of optical and optoelectronic applications. In this work, a series of all inorganic lead-free Sb3+-doped Cs2ZrCl6 vacancy-ordered perovskite variants were prepared by the hydrothermal method, and the Sb3+-doping leads to singlet and triplet state emissions, which are strongly dependent on the temperature and surrounding molecular environment. Furthermore, efficient energy transfer can be observed from self-trapped excitons (STEs) of [ZrCl6]2− octahedra to dopant Sb3+. Our results will shed light on the ns2 Sb3+-ion-doping-induced emissive mechanism and expand the understanding of the optoelectronic properties of the perovskite variant family.

Two isomeric zeolite-like metal–organic frameworks with the formula of [(CH3)2NH2][Cd(TPO)]·xsolvent were successfully prepared and characterized. Both frameworks are constructed from tetrahedral TPO3− nodes and tetrahedrally connected Cd2+ nodes, representing rare examples of zeolite-like MOFs with an isomeric characteristic. Moreover, one of the frameworks shows mechanically responsive luminescence emission after the crystals are ground for different times. Additionally, it has permanent porosity, and can selectively adsorb CO2 over N2.

A new type of bifunctional 3C synthon, a chromone–indanedione precursor, was employed for diastereoselective Michael/Michael cycloaddition with methyleneindolinones to generate a series of potentially bioactive bispiro-[chromanocyclopentane-oxindole-indanedione] frameworks with skeletal diversity in a single operation. This reaction exhibited good substrate tolerance and gave the desired products in moderate to good yields with high diastereoselectivities via an endo-transition state (up to 78% yield and >20 : 1 diastereomeric ratio). In particular, this reaction is the first example of using a chromone–indanedione precursor as a bifunctional 3C synthon, the first example of the construction of bispiro-chromanocyclopentanes, and also the first example of the introduction of a chromanocyclopentane moiety into spiroindanone frameworks, which might be valuable in medicinal chemistry.

A 1,3-sulfonyl migration of difluorovinyl sulfonates initiated by a catalytic amount of silver fluoride is presented. α,α-Difluoro-β-ketosulfones were successfully prepared in excellent yields. This method features high chemoselectivity, good functional group tolerance, high atom economy, and mild, environmentally benign reaction conditions. Furthermore, mechanistic experiments indicate that this migration proceeds in an intermolecular pathway and the corresponding sulfinates are possible intermediates.

Plant corrosion inhibitors in acid-pickling environment have the advantages of wide source, low cost and environmental protection. Pueraria lobata leaf extract (PLLE) was prepared by the combination of soaking method and ultrasonic extraction method. HPLC characterization found that PLLE contains some active ingredients, such as Puerarin, Biochanin, Daidzin and Daidzein. The corrosion inhibition of PLLE on 10# steel in 1.0 M HCl solution was studied by weight loss analysis, potentiodynamic polarization measurement, electrochemical impedance spectroscopy, scanning Kelvin probe test (SKP) and scanning electron microscopy. The results show that PLLE can effectively inhibit the corrosion of 10# steel in HCl, when the temperature is 25 °C, adding 0.5 g/L PLLE to 1.0 M HCl solution, the corrosion inhibition efficiency of 10# steel can reach up to 94.37%. The SKP results show that after adding PLLE to HCl, the surface potential difference and electrochemical non-uniformity of 10# steel are reduced, and the local corrosion tendency is significantly reduced. Polarization curves and electrochemical impedance spectroscopy indicate that PLLE is a mixed corrosion inhibitor. The adsorption process is mainly chemisorption and obeyed the Langmuir model.

Phytoremediation techniques to clean heavy metal pollution soil depend on identifying plant species that can act as phytoremediators. One important approach to screening potential phytoremediators is to evaluate characteristics of heavy metal accumulation. In this study, we performed firsthand analysis of Cd tolerance and accumulation characteristics of three Sansevieria trifasciata cultivars by pot experiment. Plant growth results showed that all three S. trifasciata cultivars can tolerate 50 mg kg−1 soil Cd concentration. After growth under 50 mg kg−1 soil Cd concentration for 4 months, the Cd bioconcentration factors in the shoots of S. ‘Trifasciata’, S. trifasciata ‘Laurentii’, and S. trifasciata ‘Silver Hahnii’ were 1.26, 1.30, and 1.19, while those in the roots were 12.53, 11.43, and 5.45, respectively. This result reveals the considerably low translocation factors of 0.10, 0.12, and 0.22 for S. ‘Trifasciata’, S. trifasciata ‘Laurentii’, and S. trifasciata ‘Silver Hahnii’, respectively. These results suggest that all three S. trifasciata cultivars had high Cd absorption capacities but low Cd translocation capacities. In combination with total Cd accumulation distribution and plant growth characteristics, S. trifasciata can be designed as a phytostabilizer in Cd-contaminated soils in its cultivation regions. Meanwhile, the mechanism of high Cd tolerance and accumulation characteristics in the roots of S. trifasciata should be explored. This study provides new resources for dealing with Cd-contaminated soils and exploring Cd tolerance and accumulation mechanisms in plants.

Trachycarpus nanus is an endangered plant that is endemic to southwest of China. In the present study, the complete chloroplast genome of this species was assembled and characterized using whole genome next-generation sequencing. The complete chloroplast genome showed a circular genome of 158,713 bp size with 36.6% GC content. The genome is of typical structure and contain a pair of inverted repeat (IR) regions with 27,240 bp, separated by one large single-copy (LSC) with 86,395 bp, and one small single-copy (SSC) regions with 17,838 bp. The genome contained 132 genes, including 86 protein-coding genes, 8 rRNA genes and 38 tRNA genes. A phylogenetic tree reconstructed based on 21 chloroplast genomes reveals that Trachycarpus nanus is most related with Chamaerops humilis. The information provides important genetic basis for the species’ future studies on phylogenetic and utilization.

We consider a pendulum type equation with p-Laplacian (ϕp(x′))′ + G′x(t, x) = p(t), where ϕp(u) = |u|p−2u, p > 1, G(t, x) and p(t) are 1-periodic about every variable. The solutions of this equation present two interesting behaviors. On the one hand, by applying Moser’s twist theorem, we find infinitely many invariant tori whenever \(\int_0^1 {p(t){\rm{d}}t = 0} \), which yields the boundedness of all solutions and the existence of quasi-periodic solutions starting at t = 0 on the invariant tori. On the other hand, if p(t) = 0 and G′x(t, x) has some specific forms, we find a full symbolic dynamical system made by solutions which oscillate between any two different trivial solutions of the equation. Such chaotic solutions stay close to the trivial solutions in some fixed intervals, according to any prescribed coin-tossing sequence.

Spatial differentiator is the key element for edge detection, which is indispensable in image processing, computer vision involving image recognition, image restoration, image compression, and so on. Spatial differentiators based on metasurfaces are simpler and more compact compared with traditional bulky optical analog differentiators. However, most of them still rely on complex optical systems, leading to the degraded compactness and efficiency of the edge detection systems. To further reduce the complexity of the edge detection system, a monolithic metasurface spatial differentiator is demonstrated based on asymmetric photonic spin-orbit interactions. Edge detection can be accomplished via such a monolithic metasurface using the polarization degree. Experimental results show that the designed monolithic spatial differentiator works in a broadband range. Moreover, 2D edge detection is experimentally demonstrated by the proposed monolithic metasurface. The proposed design can be applied at visible and near-infrared wavelengths by proper dielectric materials and designs. We envision this approach may find potential applications in optical analog computing on compact optical platforms.

A rare 3D porous inorganic–organic polyoxoniobate framework based on the cubic polyoxoniobate-cupric-complex cage {[Cu(en)2]@{[Cu2(en)2(trz)2]6(Nb68O188)}} (1a), has been successfully synthesized b...

Modeling influencing factors of battle damage is one of essential works in implementing military industrial logistics simulation to explore battle damage laws knowledge. However, one of key challenges in designing the simulation system could be how to reasonably determine simulation model input and build a bridge to link battle damage model and battle damage laws knowledge. In this paper, we propose a novel knowledge-oriented modeling method for influencing factors of battle damage in military industrial logistics, integrating conceptual analysis, conceptual modeling, quantitative modeling and simulation implementation. We conceptualize influencing factors of battle damage by using the principle of hierarchical decomposition, thus classifying the related battle damage knowledge logically. Then, we construct the conceptual model of influencing factors of battle damage by using Entity-Relationship approach, thus describing their interactions reasonably. Subsequently, we extract the important influencing factors by using social network analysis, thus evaluating their importance quantitatively and further clarifying the elements of simulation. Finally, we develop an agent-based military industry logistics simulation system by taking the modeling results on influencing factors of battle damage as simulation model input, and obtain simulation model output, i.e., new battle damage laws knowledge, thus verifying feasibility and effectiveness of the proposed method. The results show that this method can be used to support human decision-making and action.

Self-accelerating beams show considerable captivating phenomena and applications owing to their transverse acceleration, diffraction-free and self-healing properties in free space. Metasurfaces consisting of dielectric or metallic subwavelength structures attract enormous attention to acquire self-accelerating beams, owing to their extraordinary capabilities in the arbitrary control of electromagnetic waves. However, because the self-accelerating beam generator possesses a large phase gradient, traditional discrete metasurfaces suffer from insufficient phase sampling, leading to a low efficiency and narrow spectral band. To overcome this limitation, a versatile platform of catenary-inspired dielectric metasurfaces is proposed to endow arbitrary continuous wavefronts. A high diffraction efficiency approaching 100% is obtained in a wide spectral range from 9 to 13 μm. As a proof-of-concept demonstration, the broadband, high-efficiency and high-quality self-accelerating beam generation is experimentally verified in the infrared band. Furthermore, the chiral response of the proposed metasurfaces enables the spin-controlled beam acceleration. Considering these superior performances, this design methodology may find wide applications in particle manipulation, high-resolution imaging, optical vortex generation, and so forth.

Deadtime is the time period during which a detector processes the previous photon event and any later events will be ignored, thus the calculation of deadtime is of great importance to reconstruct the incident photon flux from the recorded counts. The High Energy X-ray telescope (HE) on-board the Insight-HXMT satellite records the deadtime only for a fixed time bin (i.e. 1 s), therefore it is impossible to directly obtain the deadtime for an arbitrary time interval, especially for high-energy transients much shorter than one second. Based on the electronics model of HE, we establish a deadtime calculation method to derive the deadtime in any time interval. We apply this method to transient sources observed by HE, including Gamma-ray Bursts (GRB) and Terrestrial Gamma-ray Flashes (TGF). Furthermore, since the data processing capacity of HE electronics is limited, HE suffers data saturation for very bright GRBs. During the saturation period, a significant part of counts signal cannot be recorded. We find that the amount of lost counts can be estimated by comparing the recorded 1 s deadtime and the calculated deadtime using the method mentioned above.

In this work, two rare high-dimensional polyoxoniobates with formulas of H9 [Cu(en)(H2 O)2 ][Cu(en)2 ]8 [Dy(H2 O)4 ]3 [Nb24 -O69 (H2 O)3 ]2 ⋅ 36H2 O (1) and H9 K[Cu(en)2 (H2 O)]5 [Cu(en)2 ]4 -[Eu(H2 O)4 ]3 [Nb24 O69 (H2 O)3 ]2 ⋅ 2en ⋅ 45H2 O (2) have been obtained under hydrothermal conditions. These extended materials are constructed from lanthanide-incorporated triangular-prism-like polyoxoniobate secondary building units (SBUs) {[Ln(H2 O)4 ]3 [Nb24 O69 (H2 O)3 ]2 } (Ln=Dy, Eu). 1 and 2 represent the first examples of high-dimensional polyoxometalate materials based on such lanthanide-incorporated triangular-prism-like polyoxoniobate SBUs. Furthermore, the proton conduction property and the luminescent emission of these materials were evaluated.

In this paper, we consider the monotone travelling wave solutions of a reaction–diffusion epidemic system with nonlocal delays. We obtain the existence of monotone travelling wave solutions by applying abstract existence results. By transforming the nonlocal delayed system to a non-delayed system and choosing suitable small positive constants to define a pair of new upper and lower solutions, we use the contraction technique to prove the asymptotic stability (up to translation) of monotone travelling waves. Furthermore, the uniqueness and Lyapunov stability of monotone travelling wave solutions will be established with the help of the upper and lower solution method and the exponential asymptotic stability.

The transformation behavior of ferrous sulfate was examined during hematite precipitation for iron removal in hydrometallurgical zinc. Specifically, the effects of the method used for oxygen supply (pre-crystallization or pre-oxidation of ferrous sulfate) and temperature (170–190 °C) on the redissolution and oxidation–hydrolysis of ferrous sulfate were studied. The precipitation characteristics and phase characterization of the hematite product were investigated. The results showed that the solubility of ferrous sulfate was considerably lower at elevated temperatures. The dissolution behavior of ferrous sulfate crystals was influenced by both the concentrations of free acid and zinc sulfate and the oxydrolysis of ferrous ions. Rapid oxydrolysis of ferrous ions may serve as the dissolution driving force. Hematite precipitation proceeded via the following sequential steps: crystallization, redissolution, oxidation, and precipitation of ferrous sulfate. The dissolution of ferrous sulfate was slow, which helped to maintain a low supersaturation environment, thereby affording the production of high-grade hematite.

Electronic warfare is a modern combat mode, in which predicting digital material consumption is a key for material requirements planning (MRP). In this paper, we introduce an insensitive loss function (e) and propose a e-SVR-based prediction approach. First, we quantify values of influencing factors of digital equipments in electronic warfare and a small-sample data on real consumption to form a real combat data set, and preprocess it to construct the sample space. Subsequently, we establish the e-SVR-based prediction model based on “wartime influencing factors - material consumption” and perform model training. In case study, we give 8 historical battle events with battle damage data and predict 3 representative kinds of digital materials by using the proposed approach. The results illustrate its higher accuracy and more convenience compared with other current approaches. Taking data acquisition controller prediction as an example, our model has better prediction performance (RMSE = 0.575 7, MAPE (%) = 12.037 6 and R2 = 0.996 0) compared with BP neural network model (RMSE = 1.272 9, MAPE (%) = 23.577 5 and R2 = 0.980 3) and GM (1, 1) model (RMSE = 2.095 0, MAPE (%) = 24.188 0 and R2 = 0.946 6). The fact shows that the approach can be used to support decision-making for MRP in electronic warfare.

A quinine-derived thiourea-catalyzed inter-/intramolecular Michael cycloaddition of chromone-oxindole/benzofuranone synthons with 3-substituted methylenebenzofuranones has been established, which constructed enantiomerically pure bispiro[benzofuran-oxindole/benzofuran-chromanone]s bearing five consecutive stereocenters including two spiro quaternary carton centers in good yields (up to 93%) with high diastereoselectivities (up to >20:1 dr) and good enantioselectivities (up to >99% ee). Moreover, this is the first example of bifunctional chromone-benzofuranone synthon directed organocatalytic tandem reaction, and also the first example of the bispiro[benzofuran-oxindole] and bispirobenzofuranone, potentially useful in medicinal chemistry.

A rare 3D porous chiral polyoxoniobate framework, [Cu(en)2(H2O)]2{[Cu(en)]4[Cu(en)2]5 {[Cu(en)2KNb24O72H10]2}·6en·70H2O(1) (en = ethylenediamine) based on two types of isomeric {Cu(en)2KNb24O72H10} clusters (α-CuKNb24 and β-CuKNb24) has been synthesized by a hydrothermal reaction. Interestingly, the α-CuKNb24 and β-CuKNb24 clusters are connected by cupric complexes to form chiral helical pillars with left-handedness (L-α-CuKNb24) and right-handedness (R-β-CuKNb24). To our knowledge, compound 1 is the first polyoxometalate-based MOF with a 4-connected neb-type topology structure within polyoxometalate chemistry. This compound also exhibits proton conduction and strong water vapor adsorption properties.

The encapsulation of living cells in the transformation of contaminants into green energy has great potential for solving energy and environmental pollution problems. However, some unresolved challenges related to the maintenance of the capsules' mechanical stability, biomass harvesting without leaking and necessary high activities hinder its practicability. Here, we develop a novel “interior division-external capsulation” dual-immobilization method to anchor photosynthetic bacteria into self-assembled fiber macrospheres and coating with polymer layers by phase inversion. The functional sites (C–N, C–OH and N–H) of the modified macrospheres cause more cells to adhere in the cage and its large void volume provides sufficient space for cell harvesting. Micro/nanoporous polymer shells can not only facilitate the rapid diffusion of substrates into the cavity, but also effectively reduce cell leakage. This strategy provides a facile method to significantly enhance the chemical/physical stability of the host and quickly achieve much higher activity of the encapsulated cells in the degradation of organics and H2 production as compared to free cells. Importantly, the core–shell confined encapsulation concept enables the cells to have considerable salt tolerance as high as 80 g L−1 and wide pH stability. The long-term reusability of the self-assembled macrospheres provides extensive application prospects for cell encapsulation as a clean and sustainable alternative in broader fields.

Wave plates as important polarization control devices are widely used in the applications of biomedical imaging, fiber optical communication, astronomy, semiconductor industry and aerospace etc. To make the wave plate actively tunable, we propose a rectangular antenna-based metasurface based on the phase-changing material Ge2Sb2Te5 (GST) with high transmittance and polarization conversion rate. Before the GST phase transition, the metasurface operates as a quarter-wave plate in the wavelength range of 10.0-11.9 μm. After the GST turning into crystalline state, the metasurface operates as a half-wave plate in the wavelength range of 10.3-10.9 μm. The physical mechanism for the high transmittance efficiency and polarization conversion rate attributes to the combination of the electric dipole and magnetic dipole resonances. Moreover, the adjustable wavelength range can be further extended by changing the geometry of antenna-based GST to selectively enhancing or suppressing the electric and magnetic resonances. This work provides a new strategy for tunable wave plate, which would have the potential in the application of multi-functional integrated optical systems.

Two organic–inorganic hybrid polyoxotungstogermanates, HK7(H2O)6(C6H16N2)6-[Fe(C6H14N2)Dy(H2O)2Fe2(B-α-GeW9O34)(GeW7O29)]2·14H2O (1) and (Hphen)2[Fe(phen)3]2[Dy(phen)Fe(B-α-GeW9O34)]2 (2) (C6H14N2 = trans-1,2-cyclohexanediamine, phen = 1,10-phenanthroline), containing organic ligand chelated Fe–Dy heterometallic clusters have been successfully synthesized under hydrothermal conditions. Compound 1 contains a cable-like structural fragment which consists of a centrosymmetric “S”-shaped K7O14 cluster and a centrosymmetric “S”-shaped organic ligand chelated Fe–Dy heterometallic cluster substituted tungstogermanate, {[Fe(C6H14N2)Dy(H2O)2Fe2(B-α-GeW9O34)(GeW7O29)]2}20−. Compound 2 possesses a sandwich structure which contains two trilacunary [B-α-GeW9O34]10− units and one {(phen)DyFeO6}2 cluster in the middle layer. Both compounds have magnetic properties, with compound 1 having frequency dependent magnetic properties.

In natural environments, multiple metal ions are concomitant, and their adsorption at clay mineral/water interfaces is competitive and selective. In this study, the competitive mechanisms and impac...

High-Tc ACa2Fe4As4F2 (A = K, Rb, and Cs) as novel 12442-type Fe-based superconductor has simulated great interests. The magnetic orders of Fe-based superconductor have been widely analyzed since its superconductivity competes with magnetism. The ground state of KCa2Fe4As4F2 bulk revealed by the first-principle calculation is stripe-type antiferromagnetic (AFM). However, no research on strained KCa2Fe4As4F2 films has been reported so far. Here, the compressive and tensile strain effects on the ground magnetic orders and electronic structures of KCa2Fe4As4F2 film (grown on LaAlO3 and SrTiO3 substrates, respectively) are discussed based on the first-principle calculations. The stripe-type AFM is stable responding to the compressive strain. The magnetic order is changed from stripe-type AFM of the bulk to checkerboard AFM of the tensile-strained film. This magnetism transition can be attributed to the change of density-of-states contribution of Fe-3d states.

The combination of polyoxoniobates (PONbs) with 3d metal ions, azoles, and organoamines is a general synthetic procedure for making unprecedented PONb metal complex cage materials, including discrete molecular cages and extended cage frameworks. By this method, the first two PONb metal complex cages K4 @{[Cu29 (OH)7 (H2 O)2 (en)8 (trz)21 ][Nb24 O67 (OH)2 (H2 O)3 ]4 } and [Cu(en)2 ]@{[Cu2 (en)2 (trz)2 ]6 (Nb68 O188 )} have been made. The former exhibits a huge tetrahedral cage with more than 120 metal centers, which is the largest inorganic-organic hybrid PONb known to date. The later shows a large cubic cage, which can act as building blocks for cage-based extended assembly to form a 3D cage framework {[Cu(en)2 ]@{[Cu2 (trz)2 (en)2 ]6 [H10 Nb68 O188 ]}}. These materials exhibit visible-light-driven photocatalytic H2 evolution activity and high vapor adsorption capacity. The results hold promise for developing both novel cage materials and largely unexplored inorganic-organic hybrid PONb chemistry.

The phase transformation behavior of an as-cast Ti-42Al-5 Mn (at.%) alloy after subsequent quenching from 1380 °C to 1000 °C was investigated based on the differential thermal analysis (DTA), electron probe micro analyzer-backscattered electrons (EPMA-BSE), transmission electron microscope (TEM) and X-ray diffraction (XRD). The results show that, the solidification path can be summarized as follows: Liquid→Liquid+β→β→β + α→β + α+γ→βo+α2+γ→βo+γ+α2/γ→βo+γ+α2/γ+βo,sec, with the phase transformation α→β temperature (Tβ) = 1311 °C, phase transformation γ→β temperature of (Tγsolv) = 1231 °C, phase transformation α2→α or βo→β temperature (Tα2→α/Tβo→β) = 1168 °C, eutectoid temperature (Teut) = 1132 °C and Tα2/γ→βo,sec≈1120 °C. In comparison with Ti-42Al alloy, the Teut and Tγsolv are slightly increased while both the Tβ is decreased obviously by 5% Mn addition. When quenched from the temperature of 1380-1260 °C, the martensitic transformation β→α′ could occur to form the needlelike martensite structure in β area. This kind of martensitic structure is much obvious with the increase of temperature from 1260 °C to 1380 °C. When the temperature is below Tγsolv (1231 °C), the γ grains would nucleate directly from the β phase. For the temperature slightly lower than Teut (1132 °C), the dotted βo,sec phases could nucleate in the lamellar colonies besides the γ lamellae precipitated within α2 phase. Finally, at room-temperature (RT), the alloy exhibits (βo+α2+γ) triple phase with microstructure of βo+lamellae+γ, of which the lamellar structure consists of α2, γ and βo,sec phases. The phase transformation mechanisms in this alloy, involving β→α′, β→γ, α2→α2/γ and α2→βo,sec were discussed.

A series of 3D porous lanthanide-substituted polyoxometalate frameworks, Na2[Ln2(H2O)11]2[Ln3(H2O)3(α-SiW11O39)2]2·69H2O (1-Ln, Ln = Sm, Eu, Gd, Tb, and Dy), are built from novel hexadecahedral {Ln6W8O28} heterometallic cage-shaped clusters. Intriguingly, every tetrameric {[Ln3(H2O)3(α-SiW11O39)2]2}14- cage-cluster is linked with another eight tetrameric cage-clusters by Ln3+ cations, leading to a novel 3D inorganic porous framework, which exhibits good thermal and chemical stability, excellent water vapor adsorption capacity, and moderate proton conductive properties. Furthermore, the solid state luminescence spectra demonstrate that 1-Sm, 1-Eu, 1-Tb, and 1-Dy display the lanthanide characteristic emission bands. The temperature-dependent magnetic susceptibility indicates that there are antiferromagnetic interactions in 1-Tb and 1-Dy.

During the past two decades, the search of strategies to introduce polyoxometalate (POM) clusters as secondary building units (SBUs) to construct porous extended POM-organic frameworks (POMOFs) and discrete POM-organic polyhedra (POMOPs) have attracted sustained interests because such materials not only integrate the advantages of both POMs and framework/polyhedra structures, but also exhibit good prospects in photo-/electro-catalysis, separation, molecular recognition, host-guest chemistry and so on. In this review, the recent advancements of POMOFs and POMOPs, including their assembly methodologies, classification and related applications are summarized. Moreover, the current challenges in the design and fabrication of POMOFs and POMOPs as well as the great potential in these two areas are also discussed.

Clarifying the mechanisms of heavy metal (HM) accumulation and translocation from soil-root-leaf is crucial to coping with soil HM pollution. In this study, we analysed copper (Cu), manganese (Mn), zinc (Zn) and cadmium (Cd) accumulation characteristics in Chinese turnips and the effect of soil physicochemical properties on both HM accumulation and translocation. Our results indicate that Chinese turnips absorb and translocate Mn, Zn, and Cd at much higher levels than they do Cu. When we measured bioconcentration factors in Chinese turnips for different HMs in the same soil, we found Chinese turnip capacities for HM accumulation decrease from Zn > Mn > Cd > Cu. In addition, the translocation factor for these HMs decreases from Mn > Cd > Zn > Cu. Correlation analysis indicates that soil pH and various soil components are either negatively or positively correlated with Mn, Zn, and Cd accumulation; also, soil properties are correlated with Mn translocation from root to leaf. These findings may help evaluate HM accumulation and translocation mechanisms as well as artificially regulate HM uptake levels from soils to turnips. Keywords: Turnip, Heavy metal, Bioconcentration, Phytoremediation, Soil composition

Annona reticulata is native to South and Central America which has many phytochemical and pharmacological activities suggesting a wide range of clinical application in lieu of cancer chemotherapy. This study provides abundant genomic data for the genetic relationship study, germplasm resources evaluation and varieties selection of A. reticulata. The complete chloroplast genome of A. reticulata was sequenced, assembled, and annotated in this study. The genome size was 201,906 bp and was divided into four regions: a large single-copy region of 69,650 bp, a small single-copy region of 3,014 bp, and two inverted repeat regions of 64,621 bp. A total number of 164 genes were annotated, including 115 protein-coding genes, one pseudogene, 40 tRNA genes, and eight rRNA genes. In terms of gene function, the 164 genes were divided into four major groups: genes for self-replication, photosynthesis, unknown function, and other genes. A maximum likelihood tree based on the chloroplast genome sequences of 24 plant species was constructed. The result of phylogenetic analysis showed that A. cherimola had the closest relationship with A. reticulate.

In this work, we propose dynamic holography based on metasurfaces combining spatial channel multiplexing and polarization multiplexing. In this design, spatial channels can provide up to 3N holographic frames, which not only increase the possibility of dynamic control but also increase the privacy of the holographic display. This design is also sensitive to polarization, so it further expands the spatial channel capacity. For the left and right circular polarization incident light, there are different dynamic pixel schemes. Therefore, this approach holds promise in the holographic display, optical storage, optics communication, optical encryption, and information processing.

C39H38N2O9, monoclinic, P21/c (no. 14), a = 9.9846(6) Å, b = 31.4308(13) Å, c = 11.5739(6) Å, β = 110.712(7)°, V = 3397.4(3) Å3, Z = 4, R gt (F) = 0.0596, wR ref(F 2) = 0.1221, T = 293 K.

A tetratellurium-substituted heteropolyoxoniobate with the formula K2H[Cu(phen)(H2O)]4[Cu(phen)]2[(LiNb8Te4O40)]·34H2O (1; phen = 1,10-phenanthroline) was hydrothermally prepared and structurally characterized. The compound represents the first hexavalent tellurium-substituted Keggin-type polyoxometalate (POM) so far. What is more, the POM cluster in 1 can elaborately self-assemble into a stable supramolecular framework with an ion conduction property through unique intermolecular π-π stacking.

C23H23NO6, monoclinic, P21/n (no. 14), a = 7.5845(4) Å, b = 14.7024(5) Å, c = 18.1433(6) Å, β = 98.753(4)°, V = 1999.62(14) Å3, Z = 4, R gt(F) = 0.0389, wR ref(F 2) = 0.0965, T = 293 K.

Bilayer interdiffusion heterojunction with the structure of a donor-rich region near the anode and an acceptor-rich region near the cathode could weaken the energy-level barrier between the active ...

A DBU-catalyzed inter- and intramolecular double Michael addition of donor–acceptor chromone-pyrazolone/benzofuranone synthons and 3-methyl-4-nitro-5-alkenylisoxazoles has been established, which constructed structurally diverse spiro-pyrazolone/benzofuranone-hexahydroxanthone hybrids bearing five consecutive stereocenters in good yields (up to 91%) with high diastereoselectivities (up to >20:1 dr). Moreover, this strategy further expanded the synthetic potential of bifunctional donor–acceptor chromones, and demonstrated great potential for applications in medicinal chemistry.

Cinnamomum chago is a woody species of the family Lauraceae endemic to Yunnan province, China, previously known from only one location, and categorized as a Plant Species with Extremely Small Population. We surveyed to determine the distribution and population size of C. chago, characterize its habitat, identify any threats, assess its conservation status, and provide guidelines for its management and conservation. During 2014–2017 we found only 64 mature C. chago, in five locations. These small, fragmented populations occur along Lancang River in Dali Prefecture at altitudes of 2,200–2,400 m. The species' extent of occurrence is c. 923 km2, with an area of occupancy of c. 60 km2. The habitat of the species has been degraded by expansion of pastoral activities and deforestation. We recommend categorization of C. chago as Endangered on the IUCN Red List, prevention of the collection of seeds and wood of the species, protection and monitoring, and ex situ propagation for future reintroductions.

Metasurface holograms consisting of nanostructures have shown great promise for various applications due to their unique capability of shaping light. However, most of previous work about metasurface holograms suffer from either single color or fixed colors once the metasurface holograms are fabricated. In this paper, a tunable dual-color metasurface hologram based on the extension of flexible substrate is proposed and numerically demonstrated. This scheme shows large potential in dynamic color display and information storage.

Rate-dependent hysteresis nonlinearity of the piezoelectric actuators (PEAs) deteriorates the positioning accuracy of the nano-positioning stage. To deal with it, the Gaussian Process (GP) is applied in this work to model the PEAs and also to compensate for it. The proposed GP-based model is capable of describing the nonlinear memorability as well as rate-dependence of hysteresis by introducing both the voltage value and its changing rate to the model input. The usage of the kernel function makes the model flexible and accurate without specifying a function form and the parameters. The kernel function contains only three hyperparameters, which can be determined by combining the differential evolution algorithm and Bayesian inference framework. An inverse hysteresis model is then obtained by interchanging the input and output variables of the GP-based hysteresis model to serve as a feedforward compensator. Based on this feedforward compensator, open-loop and closed-loop controllers are developed and tested. The comparative experimental studies are carried out on a PEA stage and the results demonstrate the effectiveness and superiority of the GP-based hysteresis model and compensator.

A novel perovskite type orange–red emitting phosphor Ba2ScNbO6:xEu3+ (BSN:xEu3+) was designed and synthesized by solid-state route. The X-ray diffraction, luminescent properties, fluorescent decay times and thermal stability were utilized to characterize the as-prepared samples. The X-ray diffraction confirmed BSN:xEu3+ had a cubic structure with the space group of Pm-3m (221). Photoluminescence (PL) excitation spectra consisted of a broad charge-transfer band and the f–f transition of Eu3+ ions in the violet and blue wavelength regions. The PL spectra displayed orange–red emitting luminescence with the strongest 5D0 → 7F1 transition at 595 nm. The mechanism of energy transfer between Eu3+ ions in BSN has been confirmed to be resonant type via dipole–dipole interaction. Besides, BSN:xEu3+ phosphors exhibit distinct thermal quenching properties, whose emission intensity at 423 K still exceed 71% of the initial value at room temperature. And the CIE coordinate of BSN:0.18Eu3+ phosphor is closed to the Nichia Corporation developed Amber LED NSPAR70BS. All results indicate that BSN:xEu3+ could be a promising phosphors for near-ultraviolet-based white light-emitting diodes.

The adsorption at the clay–water interface plays a critical role in many chemical, environmental, and geological processes as well as technological applications. Adsorption at the external surface ...