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A novel strategy was developed to fabricate FeNx-doped carbon quantum dots (Fe-N-CQDs) to detect Cu2+ ions selectively as a fluorescence probe. The Fe-N-CQDs were synthesized by an efficient electrolysis of a carbon cloth electrode, which was coated with monoatomic iron-anchored nitrogen-doped carbon (Fe-N-C). The obtained Fe-N-CQDs emitted blue fluorescence and possessed a quantum yield (QY) of 7.5%. An extremely wide linear relationship between the Cu2+ concentration and the fluorescence intensity was obtained in the range from 100 nM to 1000 nM (R2 = 0.997), and the detection limit was calculated as 59 nM. Moreover, the Fe-N-CQDs demonstrated wide range pH compatibility between 2 and 13 due to the coordination between pyridine nitrogen and Fe3+, which dramatically reduced the affection of the protonation and deprotonation process between H+ and Fe-N-CQDs. It is notable that the Fe-N-CQDs exhibited a rapid response in Cu2+ detection, where stable quenching can be completed in 7 s. The mechanism of excellent selective detection of Cu2+ was revealed by energy level simulation that the LUMO level of Fe-N-CQDs (−4.37 eV) was close to the redox potential of Cu2+, thus facilitating the electron transport from Fe-N-CQDs to Cu2+.

Rational design of advanced structure for transition metal oxides (TMOs) is attractive for achieving high-performance supercapacitors. However, it is hampered by sluggish reaction kinetics, low mass loading, and volume change upon cycling. Herein, hierarchical NiCo2O4 architectures with 2D-nanosheets-shell and 3D-nanocages-core (2D/3D h-NCO) are directly assembled on nickel foam via a facile one-step way. The 2D nanosheets are in-situ generated from the self-evolution of initial NCO nanospheres. This 2D/3D hierarchical structures ensure fast ion/electron transport and maintain the structural integrity to buffer the volume expansion. The 2D/3D h-NCO electrode with an ultrahigh mass loading (30 mg cm−2) achieves a high areal capacity of 4.65 C cm−2 (equivalent to 1.29 mAh cm−2) at a current density of 4 mA cm−2, and retains 3.7 C cm−2 even at 50 mA cm−2. Furthermore, the assembled solid-state hybrid supercapacitor yields a high volumetric energy density of 4.25 mWh cm−3 at a power density of 39.3 mW cm−3, with a high capacity retention of 92.4% after 5000 cycles. Therefore, this work provides a new insight to constuct hierarchical electrodes for energy storage application.

Photoelectrochemical (PEC) water-splitting using solar energy holds great promise for the renewable energy future, and a key challenge in the development of industry viable PEC devices is the unavailability of high-efficient photoanodes. Herein, we designed a TiO2 model photocatalyst with nano-groove pattern and different surface orientation using low-energy Ar+ irradiation and photoetching of TiO2, and significantly improved the intrinsic activity for PEC water oxidation. High-resolution transmission electron microscopy directly manifests that the grooves consist of highly stepped surface with steps and well-crystallized. Transient absorption spectroscopy reveals the groove surface that allows for increased recovery lifetime, which ensures promoted electron-hole separation efficiency. Surface photovoltage directly shows the carrier separation and transportation behaviors, verified by selective photodeposition, demonstrating the groove surface on TiO2 contributes to electron-hole separation. This work proposes an efficient and scalable photoanode strategy, which potentially can open new opportunities for achieving efficient PEC water oxidation performance.

Surface oxygen vacancy defects of mesoporous CeO2 nanosheets assembled microspheres (D-CeO2) are engineered by polymer precipitation, hydrothermal and surface hydrogenation strategies. The resultant D-CeO2 with a main pore diameter of 9.3 nm has a large specific surface area (~102.3 m2/g) and high thermal stability. The mesoporous nanosheets assembled microsphere structure prevents the nanosheets from aggregation, which is beneficial to effective mass transfer and shortens the migration distance of charge carriers. After surface hydrogenation, the photoresponse extends to long wavelength region, combing with the band gap from 2.63 eV reduced to 2.39 eV. Under AM 1.5 G radiation, the photocatalytic degradation rate of tetracycline (TC) can be up to 99.99%, which is three times as high as that of pristine CeO2 microspheres. The excellent solar-driven photocatalytic performance can be attributed to the efficient surface oxygen vacancy engineering and the mesoporous nanosheets assembled microsphere structure, which narrows the band gap, shortens the migration distance of carriers, promotes the spatial separation of photogenerated electron-hole pairs and favors mass transfer. The strategy provides new insights for fabricating other high-efficient oxide photocatalysts .

Potassium‐ion batteries (PIBs) are a promising candidate for next‐generation electric energy storage applications because of the abundance and low cost of potassium. However, the development of PIBs is limited by sluggish kinetics and huge volume expansion of anodes, leading to poor rate capability and cycling stability. Herein, an advanced superstructure anode, including Te-doped SnS2 nanosheets uniformly anchored on MXene surface (Te-SnS2/MXene), is rationally designed for the first time to boost K+ storage performance. Featuring with strong interface interaction and self-autoadjustable interlayer spacings, the Te-SnS2/MXene can efficiently accelerate electron/ion transfer, accommodate volume expansion, inhibit crack formation, and improve pseudocapacitive contribution during cycling. Thus, the novel Te-SnS2/MXene anode delivers a high reversible capacity (343.2 mAh g−1 after 50 cycles at 0.2 A g−1), outstanding rate capability (186.4 mAh g−1 at 20 A g−1), long cycle stability (165.8 mAh g−1 after 5000 cycles at 10 A g−1 with a low electrode swelling rate of only 15.4%), and reliable operation in flexible full battery. The present Te-SnS2/MXene becomes among the best transition metal-based anode materials for PIBs reported to date.

Barium Strontium Titanate (Ba1-xSrxTiO3, BST) possesses the advantages of high permittivity, low remnant polarization and dielectric loss, suggesting great potential in the application of power capacitors. However, the low maximum polarization severely restricts the achievement of outstanding energy storage properties (ESP). Herein, we design a lead-free bulk ceramic: (1-x)Ba0.55Sr0·45TiO3-xBi0.5Na0.5TiO3 [(1-x)BST-xBNT] (x = 0.1–0.4), prepared by two-step solid-state reaction method. The introduction of BNT contributes to (1) the boost of maximum polarization (from 21 μC/cm2 up to 32.6 μC/cm2) due to Bi3+ lone pair covalent effect (2) strong relaxor behavior (1.71≪ γ 1.84) derived from weakly coupled nanopolar regions, which can be verified by high activation energy Ea = 0.341 eV at x = 0.3, improves the ESP and thermal stability of the ceramics. According to the above strategies, high Wrec = 1.73 J/cm3 and η = 84.4% are achieved in the 0.7BST-0.3BNT ceramics at 206 kV/cm, which is preferable to the previous results regarding BST-based bulk ceramics. The excellent thermal stability (20–120 °C), frequency stability (1–500 Hz), as well as anti-fatigue characteristic (cycling number: 105) were obtained in the 0.7BST-0.3BNT. Furthermore, 0.7BST-0.3BNT ceramics exhibit high-power density (PD = 44.9 MW/cm3) and rapid discharge rate (t0.9 = 99.2 ns) from 20 °C to 120 °C. This work provides a feasible way to achieve good energy storage and charge-discharge properties for pulse power energy storage systems.

The combination of multiple loss characteristics is an effective approach to achieve broadband microwave wave absorption performance. The Fe-doped SiOC ceramics were synthesized by polymer derived ceramics (PDCs) method at 1500 °C, and their dielectric and magnetic properties were investigated at 2–18 GHz. The results showed that adding Fe content effectively controlled the composition and content of multiphase products (such as Fe3Si, SiC, SiO2 and turbostratic carbon). Meanwhile, the Fe promoted the change of the grain size. The Fe3Si enhanced the magnetic loss, and the SiC and turbostratic carbon generated by PDCs process significantly increased the polarization and conductance loss. Besides, the magnetic particles Fe3Si and dielectric particles SiO2 improved the impedance matching, which was beneficial to EM wave absorption properties. Impressively, the Fe-doped SiOC ceramics (with Fe addition of 3 wt %) presented the minimum reflection coefficient (RCmin) of −20.5 dB at 10.8 GHz with 2.8 mm. The effective absorption bandwidth (EAB, RC

To study the effects of the hard segment content of Polyurethane (PU) on the performances of polyurethane porous mixture (PPM), three PUs with different hard segment contents are selected in this paper. Firstly, the properties including hardness, elongation, e-modulus of PU were tested. Secondly, the cantabro test was used for analyzing the effect of hard segment content on the cantabro losses of the open-graded friction course 16 (OGFC16), OGFC13 and OGFC10 at the different immersed times and temperatures. Thirdly, the freeze–thaw splitting test, rutting test, friction coefficient test and three-point bending test were used for studying the road performances of OGFC13. The results of tests show that the elongation decreases with the increasing of hard segment content. The water and temperature have significant effects on the cantabro losses of PPM. The cantabro loss of PPM increases with the increasing of the immersed time and temperature. And the cantabro losses of PPM are higher than that of asphalt mixture (AM) overall. In terms of the road performance, the hard segment content of PU has a significant effect on the cantabro losses of PPM, has no effect on the tensile strength ratio (TSR). Therefore, the hard segment content of PU has a significant effect on the water stability of PPM in some cases. Besides, the hard segment content has a significant effect the dynamic stability, flexural strength and flexural tensile strain of PPM, has an effect on anti-skid ability in some cases. In the whole, the PU with smaller hard segment content is beneficial to has better road performances. Finally, the PU with the hard segment content from 41% to 51% is recommended.

In this study, MgAl2O4-based ceramics with high quality factor (Qf) and low dielectric constant (er ≤ 10) were obtained by fabricating MgAl2-x(Zn0.5Ti0.5)xO4 (x = 0–0.5) ceramics via conventional solid-state reaction method. Excellent microwave dielectric properties were achieved for samples at x = 0.5 and sintered at 1550 °C, i.e., er = 9.86, Qf = 263 900 GHz (five times better than that for x = 0 sample) and τf = −92 ppm/°C. The X-ray diffraction (XRD) patterns displayed characteristic peaks of MgAl2O4 with spinel structure. MgTi2O5 and MgTiO3 were considered as secondary phases. Scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDS) and relative density analysis indicated that ultra-high Qf values were dominated by dense microstructure, secondary phase and cation vacancies; whereas er values were mainly affected by secondary phase and ionic polarizability. MgAl2-x(Zn0.5Ti0.5)xO4 ceramics with excellent microwave dielectric properties have potential application in millimeter-wave communication, dielectric filters, dielectric antennas and resonators.

Nowadays, iron ions as a ubiquitous heavy metal pollutant are gradually concerned and the convenient and quick removal of excessive iron ions in groundwater has become a major challenge for the safety of drinking water. In this study, boron-doped biochar (B-BC) was successfully prepared at various preparation conditions with the addition of boric acid. The as-prepared material has a more developed pore structure and a larger specific surface area (up to 897.97 m²/g). A series of characterization results shows that boric acid effectively activates biochar, and boron atoms are successfully doped on biochar. Compared with the ratio of raw materials, the pyrolysis temperature has a greater influence on the amount of boron doping. Based on Langmuir model, the maximum adsorption capacity of 800B-BC1:2 at 25 °C, 40 °C, 55 °C are 50.02 mg/g, 95.09 mg/g, 132.78 mg/g, respectively. Pseudo-second-order kinetic model can better describe the adsorption process, the adsorption process is mainly chemical adsorption. Chemical complexation, ions exchange, and co-precipitation may be the main mechanisms for Fe2+ removal.

We use entropy theory as a new tool to study sectional hyperbolic flows in any dimension. We show that for C 1 flows, every sectional hyperbolic set Λ is entropy expansive, and the topological entropy varies continuously with the flow. Furthermore, if Λ is Lyapunov stable, then it has positive entropy; in addition, if Λ is a chain recurrent class, then it contains a periodic orbit. As a corollary, we prove that for C 1 generic flows, every Lorenz-like class is an attractor.

Batteries can undergo overdischarge in actual applications without triggering safety issues. The interesting one is whether the battery that is overdischarged can have a second life in the following normal charge and discharge process. Herein, the effects of overdischarge are investigated using the LiCoO2/mesocarbon microbeads (MCMB) batteries with different depth of discharge (DOD) (102% DOD, 105% DOD, and 115% DOD) for ten times; the performance and aging mechanisms of the overdischarged battery in the following normal cycling are studied mainly through the electrochemical methods, scanning electron microscopy (SEM), X-ray diffractometry (XRD), X-ray photoelectron spectroscopy (XPS), and transmission electron microscopy (TEM). For the batteries subjected to multiple shallow overdischarge (e.g., 102% DOD and 105% DOD), the aging mechanism remains unchanged, and the battery can be further used for a second life. In contrast, the multiple deep overdischarge (e.g., 115% DOD) remarkably leads to battery bulges, a drastic decrease in capacity, and a changed aging mechanism. It is noteworthy that the performance decay of LiCoO2 is deteriorated owing to the thickened Cathode-Electrolyte-Interface (CEI) and the damaged microstructure, which is different from overdischarge for one time. At the same time, the thermostability of LiCoO2 is remarkably reduced after deep overdischarge for ten times.

Piezoelectric bioorganic thin films Piezoelectric materials enable a reversible conversion between mechanical pressure and electric charge and are useful for sensors, actuators, and high-precision motors. Yang et al. developed a method for making high-quality crystalline thin films of piezoelectric γ-glycine crystals that are grown and refined between layers of polyvinyl alcohol (PVA) (see the Perspective by Berger). The PVA layers are essential to promoting the crystallization of the preferred crystal phase with the polar axis oriented perpendicular to the film plan because of hydrogen bonding at the PVA-glycine interface. The thin films show a macroscopic piezoelectric response and high stability in aqueous environments. The films are water soluble and, when suitably packaged, could be implanted into a biodegradable energy-harvesting device. Science , abf2155, this issue p. 337 ; see also abj0424, p. 278

Catastrophe insurance markets fail to provide sufficient protections against natural catastrophes, whereas they have the capacity to absorb the losses. In this paper, we assume the catastrophic risks are dependent and extremely heavy-tailed, and insurers have limited liability to cover losses up to a certain amount. We provide a comprehensive study to show that the diversification in the catastrophe insurance markets can be transited from suboptimal to preferred by increasing the number of insurers in the market. This highlights the importance of coordination among insurers and the government intervention in encouraging insurers to participate in the catastrophe insurance market to exploit risk sharing. Simulation studies are provided to illuminate the key findings of our results.

In the modeling of multivariate extreme risks, the tail dependence and the heavy tailedness are the two key factors. Heavy tailedness are usually defined through the regular variation. Tail dependence can be modeled by copulas with the so-called tail order property. In this paper, we propose a new risk measure called the Joint Expected Shortfall (JES) as an alternative of quantifying extreme risks. The JES, which can be viewed as a consolidation of both Expected Shortfall (ES) and Marginal Expected Shortfall (MES) risk measures, has the desirable property of measuring risk by jointly capturing both tail dependence and heavy tailedness. The asymptotic analysis of JES is conducted to provide a simple and transparent way of studying the interplay between tail dependence and heavy tailedness. Various examples are presented to illuminate our results. In particular, risk measures such as ES and MES that ignore the joint effect of dependence and heavy tailedness may severely underestimate the underlying risk.

The fast exploration of low energy configuration by surface atoms is believed to favor the formation of ultrastable metallic glasses, prepared by physical vapor deposition. Here, we find that the rearrangement of surface atoms is collective, rather than being dominated by individual atoms. Specifically, we experimentally observe the growth process of ultrastable metallic glasses at monolayer resolution, which follows a periodic island-layer-island pattern with morphology variation between islands and flat surfaces. The estimated surface diffusion coefficient is orders of magnitude higher than that for bulk diffusion. The fast surface dynamics allow the newly deposited clusters on the flat surface to form local islands with spherical shape, which substantially reduces the surface free energy in each island-layer-island growth cycle. Our findings are helpful for understanding the growth mechanisms of ultrastable metallic glasses and potentially for tailoring their properties. Ultrastable metallic glasses form by surface diffusion on a substrate during deposition. Here, this process is shown to involve the collective diffusion of atoms in a cyclic process, involving the formation of islands, their coalescence into a layer, followed by further island formation.

Although alluvial fans are widely distributed along the western margin of the Junggar basin, NW China, uncertainties in their formation age and associated environment need to be resolved. In a well-developed alluvial fan in the upper reaches of the Baiyang River, a 137 m-deep hydrogeological drilling core (ZK1) has been extracted. Paleomagnetic analysis shows that this section has been deposited since 8 Ma, during three distinct phases: (1) a lower segment of muddy facies formed during 8–5.6 Ma; (2) a middle segment of alternating muddy and sandy and gravel layers formed during 5.6–3.6 Ma, and (3) the upper layer of gray conglomerate formed from 3.6 Ma to present. The fan began to develop at ~5.6 Ma, perhaps driven by the Mediterranean Messinian salinity crisis originally. At 3.6 Ma, the deposition rate increased significantly and the climate further dried and cooled, likely due to the uplift of the Qinghai-Tibet Plateau and its far-field structural and environmental impacts. However, the direct causes of the two events recorded in this section are related to the rapid uplift of Wuerkashier Mt., and to regional and global climate cooling.

Engineering the nucleation and growth of plasmonic metals (Ag and Au) on their pre-existing seeds is expected to produce nanostructures with unconventional morphologies and plasmonic properties that may find unique applications in sensing, catalysis, and broadband energy harvesting. Typical seed-mediated growth processes take advantage of the perfect lattice match between the deposited metal and seeds to induce conformal coating, leading to either simple size increases (e.g., Au on Au) or the formation of core-shell structures (e.g., Ag on Au) with limited morphology change. In this work, we show that the introduction of a thin layer of metal with considerable lattice mismatch can effectively induce the nucleation of well-defined Au islands on Au nanocrystal seeds. By controlling the interfacial energy between the seed and the deposited material, the oxidative ripening, and the surface diffusion of metal precursors, we can regulate the number of islands on the seeds and produce complex Au nanostructures with morphologies tunable from core-satellites to tetramers, trimers, and dimers. This surface engineering strategy is of great significance in nanomaterial synthesis as it is general and can be used to create secondary structures of many other nanocrystals in a controllable manner.

The memristor is a foundational device for an artificial synapse, which is essential to realize next-generation neuromorphic computing. Herein, an optoelectronic memristor based on a two-dimensional (2D) transitional-metal trichalcogenide (TMTC) is designed and demonstrated. Owing to the excellent optical and electrical characteristics of titanium trisulfide (TiS3), the memristor exhibits stable bipolar resistance switching (RS) as a result of the controllable formation and rupturing of the conductive aluminum filaments. Multilevel storage is realized with light of multiple wavelengths between 400 and 808 nm, and the synaptic properties such as conduction modulation and spiking timing-dependent plasticity (STDP) are achieved. On the basis of the photonic potentiation and electrical habitual ability, Pavlovian-associative learning is successfully established on this TiS3-based artificial synapse. All these results reveal the large potential of 2D TMTCs in artificial neuromorphic chips.

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.

β-Carotene has been widely used in the food and feed industry and has significant commercial value. This study aimed to increase the β-carotene production in engineered Yarrowia lipolytica by optimizing the host metabolic network. The DID2 gene, a subunit of the endosomal sorting complex required for transport (ESCRT), was integrated into a β-carotene producing strain. The β-carotene production was increased by 260%, and the biomass increased by 10% for engineered Y. lipolytica. Meanwhile, DID2 elevated the mRNA level and protein level of the genes in the β-carotene synthesis pathway, then increased precursors (FPP, Lycopene) utilization. DID2 also increased the mRNA level of the genes in the glucose pathway, pentose phosphate pathway, and tricarboxylic acid cycle and promoted glucose utilization and cofactors consumption. The ESCRT protein complex subunit, DID2, improved β-carotene production in engineered Y. lipolytica and beneficial to glucose utilization and cofactors consumption. This study provided new finding of the DID2 gene’s function and it mostly could be used for many other natural product productions.

Although high-performance graphene-based micro/nano flexible electronic devices have shown promising applications in numerous fields, there are still many problems in converting graphene into practical applications. Heteroatom-doped graphene materials are of huge importance because heteroatom doping can significantly change the electronic structure and introduce the active site, which benefits the integration with a promising substrate and achieves nondestructive transfer of carbon materials. Herein, we analyze in detail the pyrolysis gas composition of heteroatom-enriched phosphazenes with different structures and prepare a series of high-quality in situ N, P-codoped carbon-based films from phosphazene solid sources on a low-cost glass substrate by a convenient one-step method. The N, P-codoped carbon film shows reflectivity, good conductivity, and transparency. In addition, with the help of in situ "molecular welding", we achieve nondestructive transfer of a conductive carbon-based film from a glass substrate to promising layer-polyimide (PI) and prepare a flexible free-standing carbon/PI hybrid film with an excellent binding interface. The flexible conductive hybrid film shows excellent durability under an extremely low temperature environment and superior bending stability after 800 bending cycles. The results suggest that a phosphazene precursor is an amazing choice for constructing high-quality heteroatom-doped conductive carbon films. Besides, this work provides a promising way for nondestructive transfer of the conductive carbon-based films and large-scale preparation of large-area patterned conductive thin films.

Replacing scarce and expensive platinum (Pt) with metal–nitrogen–carbon (M–N–C) catalysts for the oxygen reduction reaction in proton exchange membrane fuel cells has largely been impeded by the low oxygen reduction reaction activity of M–N–C due to low active site density and site utilization. Herein, we overcome these limits by implementing chemical vapour deposition to synthesize Fe–N–C by flowing iron chloride vapour over a Zn–N–C substrate at 750 °C, leading to high-temperature trans-metalation of Zn–N4 sites into Fe–N4 sites. Characterization by multiple techniques shows that all Fe–N4 sites formed via this approach are gas-phase and electrochemically accessible. As a result, the Fe–N–C catalyst has an active site density of 1.92 × 1020 sites per gram with 100% site utilization. This catalyst delivers an unprecedented oxygen reduction reaction activity of 33 mA cm−2 at 0.90 V (iR-corrected; i, current; R, resistance) in a H2–O2 proton exchange membrane fuel cell at 1.0 bar and 80 °C. Replacing platinum with metal–nitrogen–carbon catalysts for the oxygen reduction reaction in proton exchange membrane fuel cells has been impeded by low activity. These limitations have now been overcome by the trans-metalation of Zn–N4 sites into Fe–N4 sites.

Polyvinylidene fluoride (PVDF) thin films with high β-phase content exhibit excellent piezoelectric and dielectric properties. In this work, PVDF–NaCl composite film with high β-phase content was prepared by near-electric-field three-dimensional (3D) printing. The mechanism of the influence of NaCl on the nucleation and phase transition of the PVDF thin films was revealed based on the synergistic effect of the electric field and salt addition. The composite films were characterized by scanning electron microscopy, fourier transform infrared spectroscopy, x-ray diffraction analysis, and measurements of electrical properties. The results showed that NaCl can increase the density of the membrane, while the β-phase content and dielectric properties of the PVDF composite membrane are positively correlated with the amount of NaCl added. The β-phase content reached a maximum value of 52.68% when the amount of NaCl added was 0.05% by weight. The dielectric constant of the PVDF composite film increased with increasing NaCl content. The electrical properties also indicated that PVDF composite film with higher NaCl content showed higher electrical output voltage, while the response voltage of the composite film with 0.05 wt.% NaCl was higher than that of pure PVDF film.

An integrated approach combining scanning tunneling microscopy (STM) and X-ray photoelectron spectroscopy (XPS) is used to investigate the atomic structures and electronic properties of Cr-doped ZnO( ) surfaces. When deposited at 300 K, Cr at low surface coverage (l 0.1 ML) appeared either as isolated atoms on the surface terrace of ZnO( ) or substituting Zn atoms in the ZnO lattice. Their structural models could be identified from atomic-resolution STM images and their oxidation states were found as Cr3+ based on XPS measurements. Rectangular islands nucleated at step edges along the [0001] direction could also be observed during the initial growth of Cr at 300 K and were assigned as Cr islands. The density of Cr islands as well as their average size increased with the increasing of Cr surface loading. Thermal treatments at above 600 K could facilitate the decomposition of Cr islands and the re-dispersion of Cr atoms into the ZnO lattice, indicating a strong interaction between Cr and ZnO. The adsorption of CO at 78 K showed no preferential adsorption at Cr3+ sites embedded in the surface lattice of ZnO. However, the re-dispersion of Cr atoms into the ZnO bulk at above 600 K could induce a significant upward band bending, causing a negative shift of core level XPS peaks of Zn 2p and O 1s by ~0.5–0.7 eV. Our study has thus constructed a model catalyst for Cr-doped ZnO and provided atomic insight for understanding ZnO-based catalysts.

Space charge accumulating in oil-paper insulation structure can distort electric field. Transformer-oil, carrying space charge, might change charge transport behavior due to flow properties. In this article, the effect of oil convection on space charge is analyzed by the upstream finite element method based on vector sum. First, the velocity of transformer-oil is obtained by solving Navier–Stokes equations. It is associated with the migration to determine every upstream finite element. And then, the interpolation equation of space charge in flowing fluid is deduced to investigate the movement. Compared to traditional approaches, the velocity of flow is considered to judge the charge transport direction and to update charge density. To consider the temperature effect, a three-electrode experimental system is constructed to measure ion mobility. Finally, a flat rectangular model and a bent oil-path model are built as examples to study the movement characteristics. It is proven that convection makes a significant contribution to charge transport.

The Gaoshiti-Moxi Gas Field has been discovered recently in the central part of Sichuan Basin, which might be the biggest gas field in China. In this gas field, a large amount of gas is from Neoproterozoic Sinian (Ediacaran) karstic carbonate rocks. The gas was originated from cracking of oil, and the oil source rocks are the Sinian and Cambrian strata. In this study, the characteristics of these carbonate reservoir rocks have been studied based on subsurface data and outcrop observation. The carbonate rocks are at the Sinian Dengying Formation, and the reservoir properties are controlled by sedimentary facies and diagenesis. The Dengying Formation is composed of algal mounds and grainstone build-ups, which were developed in a restricted platform setting from glacial period to interglacial period. Due to tectonic movement and eustatic cycle in Sichuan Basin during Neoproterozoic Era, five sedimentary cycles of transgression and regression have been developed in the Dengying Formation. According to the sedimentary facies and carbon-oxygen isotope variation, five sedimentary cycles have been recognized. Due to the penecontemporaneous dolomitization, together with hypergene karstification and late burial dissolution, the reservoir properties of the carbonates rocks have been improved greatly.

Numerous Late Paleozoic to Early Mesozoic mafic-ultramafic intrusions occur along the northern margin of the North China Craton (NCC). The timing, magma source, genetic types and tectonic evolution of these intrusions still remain controversial. Here we conduct a systematic petrological, mineral chemical, whole-rock geochemical, isotopic (zircon Lu–Hf and whole-rock Sr–Nd isotopes) and geochronological study on representative samples from the Chicheng ultramafic complex in the northern NCC, our results provide new insights into multiple melt-fluid interactions in the subcontinental lithospheric mantle through time. Zircon U–Pb data from the ultramafic rocks (pyroxenite and serpentinized dunite) show a wide range of ages (2721–129 Ma), indicating zircon growth within an evolving and metasomatized mantle wedge during multi-stage melt-fluid interactions. The youngest zircon population (145–129 Ma) possibly marks the timing of formation of the Chicheng ultramafic complex at the Early Cretaceous. Moreover, these ultramafic rocks also witnessed tectonic transition from Paleo-Asian Ocean to Paleo-Pacific Plate subduction during the Paleozoic to Early Mesozoic and subsequent progressive lithospheric thinning and craton destruction at the northern margin of the NCC, which is also attested by the newly discovered diorite porphyry dyke from this complex reported in this study with zircon U–Pb ages in the range of 447 to 128 Ma. Zircon Lu–Hf isotopic data show eHf(t) values in the range of −19.9 to +15.4 with TDM of 219–3012 Ma and TDMC of 240–3650 Ma. Whole-rock Sr–Nd isotopic data display eNd(t) values ranging from −12.3 to −1.6, indicating heterogenous sources involving both depleted mantle and reworked ancient crustal components. Whole-rock geochemical data show enrichment in LILEs (Rb, Sr, Ba, Pb) and depletion in HFSEs (Nb, Ta, Ti), with positive anomalies at Ba, K, Pb and Nd and strongly negative Zr and Ti anomalies, suggesting geochemical affinities related to subduction-related island arc setting within an active continental margin. Mineral chemical data on clinopyroxenes do not correspond to “Alaskan-type” affinities. Integrating geochemical, geochronological and isotopic studies from this study and those from previous studies related to the mafic-ultramafic complexes in the northern Hebei Province along the northern margin of the NCC, we propose that these complexes might be composite plutons formed during the Early Cretaceous, which were derived from the interaction of melts and fluids released from subducted slab with metasomatized mantle peridotite, triggering different degree of partial melting of mantle wedge.

Early seedling development is one of the most crucial period of the plant's life cycle, which is highly susceptible to adverse environmental conditions, especially those impose by salt stress. Castor plant (Ricinus communis) is a famous non-edible oilseed and salt-resistant crop worldwide. However, the specific metabolic responses in the cotyledons and roots of this species during seedling establishment under salt stress are still not clearly understood. In the present study, 16 d castor seedlings were treated with 150 mM NaCl for 6 d, and the metabolite profiling of cotyledons and roots was conducted using liquid chromatography (LC) combined with electrospray ionization time-of-flight mass spectrometry (ESI-TOF-MS). The Principal Component Analysis (PCA) results showed that the metabolites were great differed in cotyledons and roots under salt stress. There were 38 differential metabolites, mainly including fatty acid, nucleic acid and organic acids in the cotyledons, but only 19 differential metabolites, mainly including fatty acid and organic acids in the roots under such condition. Furthermore, Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway enrichment analysis revealed that flavone and flavonol biosynthesis, pantothenate and CoA biosynthesis, citrate cycle and carotenoid biosynthesis were the common metabolic pathways in response to salt stress in the two organs. Salt stress caused metabolite process alteration mainly on carbon and nitrogen metabolisms, and the carbon allocation from root to cotyledon was increased. Additionally, changes of amino acids and nucleic acids profiles were only found in the cotyledons, and the roots could enhance the activity of antioxidant enzyme systems to scavenge ROS under salinity. In conclusion, the present research provides an improved understanding on specific physiological changes in the cotyledons in castor early seedlings, and explores their interaction under salt stress.

By employing accurate state‐of‐the‐art many‐electron quantum‐chemistry methods, we establish that monocyclic carbon rings can accommodate Li guest atoms. The low‐lying electronic states of these endocircular systems are analyzed and found to include both charge‐separated states where the guest Li atom appears as a cation and the ring as an anion and encircled‐electron states where Li and the ring are neutral. The electron binding energies of the encircled‐electron states increase drastically at their highly symmetric equilibrium geometries with increasing size of the ring, and in Li@C24, this state becomes the ground state. Li is very weakly bound vertical to the rings in the low‐lying encircled‐electron states, hinting to van‐der‐Waals binding. Applcations are mentioned., Endocircular Li carbon rings exhibit two types of electronic states of very different nature, the ordering of which changes with the ring size. This enables possible interesting applications by excitations from the electronic ground states to states of different nature depending on the ring size.

通过表面氧空位缺陷调控催化剂的表面电子结构, 实现催化剂表面易于富集参与反应的电子, 从而提高还原催化效率. 本文中, 将导电玻璃隔绝空气加热, 在其表面形成氧空位缺陷. 通过控制热处理时间调控表面氧空位浓度梯度. 氧空位能导致SnO2导带弯曲, 因此调控氧空位梯度可增强SnO2导电玻璃表面电子富集速率, 从而实现高效电催化还原反应. 在相同条件下, 使其催化性能可以和金属铂相媲美.

The shuttling of polysulfides is the most detrimental contribution to degrading the capacity and cycle stability of lithium-sulfur (Li-S) batteries. Adding a carbon interlayer to prevent the polysulfides from migrating is feasible, and a rational design of the structures and surface properties of the carbon layer is essential to increasing its effectiveness. Herein, we report a hierarchical porous carbon (HPC) created by carbonization of bis(phenoxy)phosphazene and in-situ doping of triple heteroatoms into the carbon lattice to fabricate an effective polysulfide-trapping interlayer. The generated carbon integrates the advantages of a hierarchical porous structure, a high specific area and rich dopants (N, O and P), to yield chemisorption and physical confinement for polysulfides and fast ion-transport synergistically. The HPC interlayer significantly improves the electrochemical performance of Li-S batteries, including an exceptional discharge capacity of 1509 mA h/g at 0.06 C and a high capacity retention of 83.7 % after 250 cycles at 0.3 C. This work thus proposes a facile in-situ synthesis of heteroatom-doped carbon with rational porous structures for suppressing the shuttle effect.

A wing is an important part of the aircraft to improve aerodynamic performance. The current study is focused on an adaptive surrogate algorithm for airfoil aerodynamic optimization, which is based on a multi-output Gaussian process model. The conventional design method seriously relies on wind tunnel experiments and expensive computational simulations. The metamodels can significantly improve design efficiency and hence reduce the overall design costs. An active learning algorithm is proposed to improve the effectiveness of the multi-output Gaussian process model. The NSGA-II algorithm is adopted to obtain the optimal Pareto set with the optimization objectives of lift and drag coefficients for adaptive airfoil shapes. Besides, the Bezier curve and radial basis function are utilized in this study for airfoil mesh deformation. The results show that the airfoil shape can be obtained effectively by integrating the metamodel, active learning algorithm, and multi-objective optimization algorithm. The optimized results are of great engineering applications.

Known mineralized locations and randomly chosen non-mineralized locations are used traditionally as training samples in data-driven mineral prospectivity mapping (MPM). In this paper, we took advantage of (a) the variable importance and partial dependence plot, which enable interpretation of random forest (RF) modeling, and (b) the synthetic minority over-sampling technique, and investigated the efficacy of outlier-based training samples used for data-driven MPM in contrast to traditional practice of using known mineralized locations as positive training samples. The prediction maps obtained by RF modeling based on different sets of training samples suggest bias toward known mineralized locations in data-driven MPM. The proposed outlier-based training samples for data-driven MPM involve both unsupervised learning and supervised learning. The former aims at outlier detection, while the latter uses the resulting outliers as positive training samples to investigate the following: firstly, the delineation of prospective area or spatial signature of existing mineral system by avoiding the bias arising from the known mineralized locations in data-driven MPM and secondly, the coherence of spatial signature of outliers, which justifies their feasibility as positive training samples for data-driven MPM by RF modeling. Analyses of receiver operating curves and correlations of the resulting prediction maps imply that outliers derived by isolation forest show consistent spatial signature as the known mineralized location and, thus, were effective in narrowing down the prospective target areas just like in traditional data-driven MPM.

The extension of the cosmic-ray spectrum beyond 1 petaelectronvolt (PeV; 1015 electronvolts) indicates the existence of the so-called PeVatrons—cosmic-ray factories that accelerate particles to PeV energies. We need to locate and identify such objects to find the origin of Galactic cosmic rays1. The principal signature of both electron and proton PeVatrons is ultrahigh-energy (exceeding 100 TeV) γ radiation. Evidence of the presence of a proton PeVatron has been found in the Galactic Centre, according to the detection of a hard-spectrum radiation extending to 0.04 PeV (ref. 2). Although γ-rays with energies slightly higher than 0.1 PeV have been reported from a few objects in the Galactic plane3–6, unbiased identification and in-depth exploration of PeVatrons requires detection of γ-rays with energies well above 0.1 PeV. Here we report the detection of more than 530 photons at energies above 100 teraelectronvolts and up to 1.4 PeV from 12 ultrahigh-energy γ-ray sources with a statistical significance greater than seven standard deviations. Despite having several potential counterparts in their proximity, including pulsar wind nebulae, supernova remnants and star-forming regions, the PeVatrons responsible for the ultrahigh-energy γ-rays have not yet been firmly localized and identified (except for the Crab Nebula), leaving open the origin of these extreme accelerators. Observations of γ-rays with energies up to 1.4 PeV find that 12 sources in the Galaxy are PeVatrons, one of which is the Crab Nebula.

The underbody of a vehicle system, either military or civil, is typically made of a relatively thin metallic plate, thus vulnerable to mine blast attacks. To improve the blast resistance, a multitude of protective structures have been proposed as attachments to the thin plate. In the present study, a novel ultralight all-metallic sandwich panel with three-dimensional (3D) tube cellular cores mounted to the vehicle underbody was envisioned as such a protective system. A metallic substrate (mimicking vehicle bottom) was placed above the proposed sandwich panel to construct a sandwich-substrate combinative structure. A series of sandwich panels having 3D tube cellular cores were fabricated via argon protected welding and laser welding. Mechanical responses of the combinative structure subjected to the denotation of 6 kg TNT explosives shallow-buried in dry sand were experimentally measured. Full numerical simulations with the method of finite elements (FE) were subsequently carried out to explore the physical mechanisms underlying the observed dynamic performance and quantify the effects of key geometrical parameters and connection conditions of the protective system. The performance of the proposed sandwich panel under shallow-buried explosives was also compared with competing sandwich constructions having equal mass. Finally, a preliminary optimal design of the 3D tube cellular core was carried out.

The combination of graphene oxide (GO) and iron oxide (Fe2O3) may induce property enforcement and application extension. Herein, GO/Fe2O3 nanocomposites were synthesized via the vacuum-freeze-drying method and used for the thermal decomposition of ammonium perchlorate (AP). A series of characterization techniques were applied to elucidate the as-obtained nanomaterial's physicochemical properties. These results show that the treated GO is consistent with the pristine GO after the freeze-drying treatment. Transmission electron microscopy (TEM) and scanning electron microscopy (SEM) analyses show that iron oxide nanoparticles are anchored on and between the GO sheets. The catalytical effect investigation on AP with different Fe2O3: GO ratios indicates that the high-temperature decomposition temperature of AP could be decreased by a temperature as high as 77 °C compared to pure AP accompanied by 3 wt % GO/Fe2O3 nanocomposite which proves the high catalytic performance of the nanocomposites. The first-principles calculation was employed to elaborate the synergistic effect, and the findings demonstrate that the presence of graphene in the catalyst can enhance the catalytic effect via reducing the activation energy barrier by ∼17% in the reaction of AP thermal decomposition.

Alkylation of benzene to value-added, high octane number and low toxic toluene and xylenes provides a way to lower benzene content in gasoline pool, and is hence a method to promote fuel quality. On the other hand, CO2 accumulation in the atmosphere causes global warming and requires effective route for its valorization. Utilization of CO2 as a carbon source for benzene alkylation could achieve both goals. Herein, alkylation of benzene with CO2 and H2 was realized by a series of low-cost bifunctional catalysts containing zinc/titanium oxides (Zn/Ti oxides) and HZSM-5 molecular sieves in a fixed-bed reactor. By regulating and controlling oxygen vacancies of Zn/Ti oxides and the acidities of HZSM-5, benzene conversion and CO2 conversion reached 28.7% and 29.9% respectively, along with a total selectivity of toluene and xylene higher than 90%. In this process, more than 25% CO2 was effectively utilized and incorporated into the target products. Moreover, the mechanism of the reaction was analyzed and the course was simultaneously traced. CO2 was transformed into methanol firstly, and then methanol reacted with benzene generating toluene and xylene. The innovation provides a new method for upgrading of fuels and upcycling the emissions of CO2, which is of great environmental and economic benefits.

Single-molecule Förster resonance energy transfer (smFRET) is a powerful tool for investigating the dynamic properties of biomacromolecules. However, the success of protein smFRET relies on the precise and efficient labeling of two or more fluorophores on the protein of interest (POI), which has remained highly challenging, particularly for large membrane protein complexes. Here, we demonstrate the site-selective incorporation of a novel unnatural amino acid (2-amino-3-(4-hydroselenophenyl) propanoic acid, SeF) through genetic expansion followed by a Se-click reaction to conjugate the Bodipy593 fluorophore on calmodulin (CaM) and β-arrestin-1 (βarr1). Using this strategy, we monitored the subtle but functionally important conformational change of βarr1 upon activation by the G-protein coupled receptor (GPCR) through smFRET for the first time. Our new method has broad applications for the site-specific labeling and smFRET measurement of membrane protein complexes, and the elucidation of their dynamic properties such as transducer protein selection., A facile bioconjugation reaction for site-specific protein modification was developed for smFRET measurement, which detected the subtle but important conformational change of the β-arrestin/GPCR complex for the first time.

Photorespiration consumes fixed carbon and energy generated from photosynthesis to recycle glycolate and dissipate excess energy. The aim of this study was to investigate whether we can use the energy that is otherwise consumed by photorespiration to improve the production of chemicals which requires energy input. To this end, we designed and introduced an isoprene synthetic pathway, which requires ATP and NADPH input, into the cyanobacterium Synechocystis sp. 6803. We then deleted the glcD1 and glcD2 genes which encode glycolate dehydrogenase to impair photorespiration in isoprene-producing strain of Synechocystis. Production of isoprene in glcD1/glcD2 disrupted strain doubled, and stoichiometric analysis indicated that the energy saved from the impaired photorespiration was redirected to increase production of isoprene. Thus, we demonstrate we can use the energy consumed by photorespiration of cyanobacteria to increase the energy-dependent production of chemicals from CO2.

SiCN-based ceramics with broadband and strong microwave absorption properties are desired for the structural and functional integration of ceramic matrix composites. The elemental composition and thermal expansion coefficients of the ceramics matrix crucially affect its microstructure and electromagnetic wave (EMW) absorption properties. BN layer with lower electrical conductivity and higher specific area, exhibits both the impedance matching characteristic and EMW attenuation in the process of multiple reflections, electrical conductivity loss, dipole polarization and interfacial polarization. Therefore, Si3N4-BN-SiCN ceramics, which were synthesized using chemical vapor infiltration (CVI) method, construct unique hetero-interface of Si3N4-BN, Si3N4–SiCN and BN-SiCN. Therefore, the Si3N4-BN-SiCN ceramics have outstanding EMW absorption performance and realize an effective absorption bandwidth (EAB) that covers the whole X band and the minimum reflection coefficient (RC) reaches -18.43 dB at a thickness of 3.37 mm.

Supplying Ca2+ and MT can be a key approach to elucidating the diverse physiological and biochemical mechanisms of plant growth, development, and resistance under environmental stresses. Although many studies have demonstrated the positive effects of exogenous melatonin (MT) under diverse stresses, most are related to crops and few have focused on woody trees. Moreover, the best outcomes related to the positive influence of MT on plants under chilling stress were obtained by applying MT alone. Thus, this work aimed to boost the strength of MT in the woody plant Dalbergia odorifera under cold stress through combination with the signaling molecule Ca2+, which has a major role in plant defense against abiotic stresses. Results showed that in D. odorifera seedlings, exogenous MT and Ca2+ application improved growth traits and relieved injuries, whereas chilling stress caused injuries and reduced growth. Exogenous MT and Ca2+increased photosynthetic activity and compatible solute (proline, glucose, fructose, and sucrose) accumulation. Starch degradation induced by chilling stress was significantly reduced in seedlings under treatment with MT combined with Ca2+. Furthermore, in D. odorifera seedlings, relative conductivity, lipid peroxidation, and reactive oxygen species were elevated under cold stress, whereas these indexes were strongly decreased by exogenous MT and Ca2+. Exogenous MT and Ca2+ enhanced the antioxidant activities against chilling stress. In addition, in D. odorifera seedlings under cold stress, exogenous MT and Ca2+ strongly elevated the levels of the phytohormones gibberellin (GA3) and auxin (IAA) but decreased those of abscisic acid (ABA) was decreased. The IAA and GA3 contents were increased respectively by 17.34% and 22.47% in seedlings treated with MT-Ca2+ compared to MT treatment. Meanwhile, the ABA content was decreased by 44.80% in MT-Ca2+-treated seedlings compared to MT treatment. In conclusion, exogenous MT and Ca2+ improved chilling stress tolerance in D. odorifera seedlings by regulating phytohormones, osmolytes, and antioxidant activities.

Sand production has become a common phenomenon in the exploitation of unconsolidated natural gas hydrate reservoirs, which will hinder the long-term production of natural gas hydrate reservoirs. However, there are few literatures reported on the influences in reservoir physical properties such as permeability and porosity, and production laws caused by sand production. This paper provides a numerical model, coupled with reservoir sand-gas-water multiphase flow processes, which is capable to simulate the process of sand production in natural gas hydrate reservoirs. The simulation results indicate that sand settlement is mainly concentrated near the wellbore due to the high concentration of migrated sand. The decrease in reservoir porosity and permeability caused by sand settlement has a significant impact on production. The impact of sand production on reservoir fluid fluidity shows that fluid flow is inhibited near the wellbore, while fluid flow performance increases far away from the wellbore. The numerical model and analysis presented here could provide useful insight into changes in reservoir physical properties and production laws caused by sand production in the natural gas hydrate-bearing marine sediments using depressurization method.

In this paper, the inverse problem for identifying the initial value of time-fractional diffusion wave equation on spherically symmetric region is considered. The exact solution of this problem is ...

For biomedical photoacoustic applications, an ongoing challenge in simultaneous volumetric imaging and spectroscopic analysis arises from ultrasonic detectors lacking high sensitivity to pressure transients over a broad spectral bandwidth. Photoacoustic impulses can be measured on the basis of the ultrafast temporal dynamics and highly sensitive response of surface plasmon polaritons to the refractive index changes. Taking advantage of the ultra-sensitive phase shift of surface plasmons caused by ultrasonic perturbations instead of the reflectivity change [as is the case for traditional surface plasmon resonance (SPR) sensors], a novel SPR sensor based on phase-shifted interrogation was developed for the broadband measurement of photoacoustically induced pressure transients with improved detection sensitivity. Specifically, by encoding the acoustically modulated phase change into time-varying interference intensity, our sensor achieved an almost five-fold sensitivity enhancement (∼98 Pa noise-equivalent pressure) compared with the reflectivity-mode SPR sensing technologies (∼470 Pa) while retaining a broadband acoustic response of ∼174 MHz. Incorporating our sensor into an optical-resolution photoacoustic microscope, we performed label-free imaging of a zebrafish eye in vivo, enabling simultaneous volumetric visualization and spectrally resolved discrimination of anatomical features. This novel sensing technology has potential for advancing biomedical ultrasonic and/or photoacoustic investigations.

Direct electricity generation from water flow/evaporation, coined hydrovoltaic effect, has recently attracted intense interest as a facile approach to harvest green energy from ubiquitous capillary water flow or evaporation. However, the current hydrovoltaic device is inferior in output power efficiency compared to other renewable energy devices. Slow water evaporation rate and inefficient charge collection at device electrodes are two fundamental drawbacks limiting energy output efficiency. Here, we report a bioinspired hierarchical porous fabric electrode that enables high water evaporation rate, efficient charge collection, and rapid charge transport in nanostructured silicon-based hydrovoltaic devices. Such an electrode can efficiently collect charges generated in nanostructured silicon as well as induce a prompt water evaporation rate. At room temperature, the device can generate an open-circuit voltage (Voc) of 550 mV and a short-current density (Jsc) of 22 μA·cm-2. It can output a power density over 10 μW·cm-2, which is 3 orders of magnitude larger than all those reported for analogous hydrovoltaic devices. Our results could supply an effective strategy for the development of high-performance hydrovoltaic devices through optimizing electrode structures.

Lead-free ceramic capacitors play an important role in electrical energy storage devices because of their ultrafast charge/discharge rates and high power density. However, simultaneously obtaining large energy storage capability, high efficiency and superior temperature stability has been a huge challenge for practical applications of ceramic capacitors. Here, the relaxor ferroelectric (1-x)[0.8Bi0.5Na0.5TiO3-0.2Ba(Zr0.3Ti0.7)O3]-xSr0.7La0.2TiO3 ((1-x)(BNT-BZT)-xSLT) ceramics are prepared through solid-state reaction method to obtain excellent comprehensive energy storage performances. Particularly, high recoverable energy density (Wrec ∼ 2.6 J/cm3) as well as superior efficiency (η ∼ 92.2 %) can be achieved simultaneously under 210 kV/cm with composition of x = 0.3. Meanwhile, the corresponding ceramic shows excellent temperature (20−140 °C), frequency (1−200 Hz) and cycle stabilities (106 st). Additionally, the 0.7(BNT-BZT)-0.3SLT ceramic also displays high power density (PD ∼ 38.8 MW/cm3) and extremely short discharge time (τ0.9 ∼ 0.11 μs). Therefore, this study provides a useful guideline for designing novel BNT-based ceramics with superior comprehensive energy storage performances.

Anaerobic digestion is promising for waste activated sludge (WAS) degradation. However, conventional processes were generally stuck with limited hydrolysis and poor pathogen destruction. Hyperthermophilic digestion at 70 °C has drawn attention in overcoming those issues at a relatively low energy requirement and operating difficulties. In order to illuminate its operation characteristics, a single-stage hyperthermophilic digester was controlled at 70 °C and operated continuously to degrade WAS. 88.7 mL/g VSadded of methane yield could be achieved in the hyperthermophilic system, fourfold higher than that in the mesophilic system. Kinetic analysis revealed that hyperthermophilic digestion was advantageous in converting the non-degradable fraction. Consequently, hydrolysis under the hyperthermophilic condition was able to be significantly improved. Above 10 d was necessary for the hyperthermophilic system to gain such a high methane production. In the case of stability, the organic loading of higher than 10.2 g VS/L/d resulted in increasing limitation from methanogenesis and accumulation of propionic, butyric and valeric acids. In addition to the dominant acetoclastic genus Methanothrix for methane production in the hyperthermophilic system, two hydrogenotrophic methanogens Methanospirillum and Methanothermobacter reached 18.84% and 8.31%, respectively. The genus Coprothermobacter, affiliated with the phylum Firmicutes, made more contribution to protein hydrolysis in the hyperthermophilic digester.

Developing microwave absorption (MA) materials with satisfied comprehensive performance is a great challenge for tackling severe electromagnetic pollution. In particular, the magnetic component/carbon hybrids absorbers always suffer from high filler loading. Herein, we propose a feasible strategy to construct hierarchical porous carbon with tightly embedded Ni nanoparticles (Ni@NPC). These highly dispersed Ni nanoparticles produce strong magnetic coupling networks to enhance magnetic loss abilities. Moreover, the interconnected hierarchical dielectric carbon network affords favorable dipolar/interfacial polarization, conduction loss, multiple reflection and scattering. Impressively, with an ultralow filler loading of 5 wt.%, the resultant Ni@NPC/paraffin composite achieves an excellent MA performance with a minimum reflection loss of as high as -72.4 dB and a broad absorption bandwidth of 5.0 GHz. This capability outperforms most current magnetic-dielectric hybrids counterparts. Furthermore, the MA capacity can be easily tuned with adjustments in thickness, content and type of magnetic material. Thus, this work opens up new avenues for the development of high-performance and lightweight MA materials.

Background An efficient supply of reducing equivalent is essential for chemicals production by engineered microbes. In phototrophic microbes, the NADPH generated from photosynthesis is the dominant form of reducing equivalent. However, most dehydrogenases prefer to utilize NADH as a cofactor. Thus, sufficient NADH supply is crucial to produce dehydrogenase-derived chemicals in cyanobacteria. Photosynthetic electron is the sole energy source and excess electrons are wasted in the light reactions of photosynthesis. Results Here we propose a novel strategy to direct the electrons to generate more ATP from light reactions to provide sufficient NADH for lactate production. To this end, we introduced an electron transport protein-encoding gene omcS into cyanobacterium Synechococcus elongatus UTEX 2973 and demonstrated that the introduced OmcS directs excess electrons from plastoquinone (PQ) to photosystem I (PSI) to stimulate cyclic electron transfer (CET). As a result, an approximately 30% increased intracellular ATP, 60% increased intracellular NADH concentrations and up to 60% increased biomass production with fourfold increased d-lactate production were achieved. Comparative transcriptome analysis showed upregulation of proteins involved in linear electron transfer (LET), CET, and downregulation of proteins involved in respiratory electron transfer (RET), giving hints to understand the increased levels of ATP and NADH. Conclusions This strategy provides a novel orthologous way to improve photosynthesis via enhancing CET and supply sufficient NADH for the photosynthetic production of chemicals.