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Emerging caloric cooling technology provides a green alternative to conventional vapor-compression technology which brings about serious environmental problems. However, the reported caloric materials are much inferior to their traditional counterparts in cooling capability. Here we report the barocaloric (BC) effect associated with the liquid-solid-transition (L-S-T) in n-alkanes. A low-pressure of ~50 MPa reversibly triggers an entropy change of ~700 J kg−1 K−1, comparable to those of the commercial refrigerants in vapor-based compression systems. The Raman study and theoretical calculations reveal that applying pressure to the liquid state suppresses the twisting and random thermal motions of molecular chains, resulting in a lower configurational entropy. When the pressure is strong enough to drive the L-S-T, the configurational entropy will be fully suppressed and induce the colossal BC effect. This work could open a new avenue for exploring the colossal BC effect by evoking L-S-T materials., Barocaloric effect, previously reported in solid-solid phase transition materials, offers a green alternative to current cooling technology. Here the authors report colossal BCE in n-alkanes associated with liquid–solid transition.

The polycrystalline CaBi2Nb2O9 ceramics with the addition of B2O3 can realize a large d33 of 20.4 pC N−1 and an ultra-high electrical resistivity of 1.4 × 107 Ω cm (at 600 °C), while still retaining a high TC of 958 °C.

Abundant vacancies in VS2 can unlock the transport of Zn2+ along the c-axis, and zinc dendrite growth can be effectively suppressed by an external weak magnetic field, achieving an excellent electrochemical performance.

We report the structure, dielectric, ferroelectric and piezoelectric properties of Cr-Mn co-doped (1-y)BiFe1-xCrxO3-yBaTi1-xMnxO3 (0≤x≤0.04, 0.2≤y≤0.27) ceramics. By varying both x and y, a series of samples near morphotropic phase boundaries exhibiting both high ferroelectric Curie temperature TC (∼580−643 °C) and relatively large piezoelectric constant d33 are constructed. Especially, the sample with y = 0.24 and x = 0.02 is found to show coexistence of high depolarization temperature Td (∼551 °C) and relatively large d33∼116 pC/N, superior to most of those of BiFeO3 based high-temperature piezoceramics reported previously. The enhanced ferroelectric TC in the Cr-Mn modified samples can be ascribed to the combined effects of large lattice distortion and high tetragonal phase content. These results demonstrate that constructing morphotropic phase boundaries via considering simultaneously the role of lattice distortion might be effective route to realize high-temperature and high piezoelectricity in BiFeO3-based systems.

The effects of quenching on the structural, electrical, dielectric, ferroelectric (FE), and piezoelectric properties are investigated systematically in the 0.85BiFe

A novel enhanced oil recovery (EOR) method based on polymer gel-assisted carbon dioxide (CO2) huff and puff was developed aiming to improve the development effect of heavy oil reservoirs with high water cut. The polymer gel prepared using partially hydrolyzed polyacrylamide (HPAM), hexamethylenetetramine, phenol, resorcinol, oxalic acid, and thiocarbamide as raw materials had a special network structure to overcome the challenge of significant heterogeneity in heavy oil reservoirs. The strength of polymer gel reached the maximum value 20,000 mPa·s within 22 h. The temperature resistance and salt resistance of polymer gel directly determined the plugging effect. The polymer gel was placed for 190 days at 85 ℃, and its apparent viscosity retention rate was 66.4%. The salt resistance experiments showed that the apparent viscosity retention rate of this polymer gel at 1.8 wt % NaCl, 0.045 wt % CaCl2, 0.045 wt % MgCl2 was 71.3%, 78.5%, 71.4%, respectively. Huff and puff experiments confirmed that this method could be used to increase the sweep volume and improve the oil displacement efficiency of heavy oil reservoirs with high water cut. Furthermore, the EOR of this method was better than that of water huff and puff, polymer gel huff and puff or CO2 huff and puff.

The outbreak of novel coronavirus pneumonia (COVID-19), defined as a worldwide pandemic, has been a public health emergency of international concern. Pudilanxiaoyan oral liquid (PDL), an effective drug of Traditional Chinese Medicine (TCM), is considered to be an effective and alternative means for clinical prevention of COVID-19. The purpose of this study was to identify potential active constituents of PDL, and explore its underlying anti-COVID-19 mechanism using network pharmacology. Integration of target prediction (SwissTargetPrediction and STITCH database) was used to elucidate the active components of PDL. Protein–protein interaction network analyses, gene ontology, Kyoto Encyclopedia of Genes and Genomes pathway enrichment analyses, network construction, and molecular docking were applied to analyze the prospective mechanisms of the predicted target genes. Our results showed that the key active ingredients in PDL were luteolin, apigenin, esculetin, chrysin, baicalein, oroxylin A, baicalin, wogonin, cymaroside, and gallic acid. A majority of the predicted targets were mainly involved in the pathways related to viral infection, lung injury, and inflammatory responses. An in vitro study further inferred that inhibiting the activity of nuclear factor (NF)-кB signaling pathway was a key mechanism by which PDL exerted anti-COVID-19 effects. This study not only provides chemical basis and pharmacology of PDL but also the rationale for strategies to exploring future TCM for COVID-19 therapy.

To solve the design problem of non-circular gear with cusp pitch curve, this paper proposed a new involute and incomplete variable cycloid composite tooth profile, deduced the new involute and incomplete variable cycloid composite profile mathematical model, and constructed the conjugate gear model based on the envelope method. The design software of non-circular gear with cusp pitch curve was developed based on MATLAB. The variation law of rolling radius on incomplete cycloid profile and its characteristics such as pressure angle and radius of curvature were analyzed. The variation relationship of rolling radius on involute and incomplete cycloid composite profile meshing line and contact ratio were studied. The variation relationship of incomplete cycloid profile shape, pressure angle, curvature radius corresponding to different elliptical eccentricity were analyzed. The meshing analysis of the non-circular gear transmission mechanism was carried out based on virtual software. Comparison of the consistency of theoretical value, simulation value of the transmission ratio curve verified that the tooth profile design method was feasible, and the composite tooth profile was applied to the seedling pick-up mechanism of the non-circular gear planetary gear train. Through the seedling picking experiment of the seedling pick-up mechanism, the feasibility of the application of the involute and incomplete variable cycloid composite tooth profile was verified.

In this work, we study the UAV-enabled data collection problem for high information freshness in wireless sensor networks, where one UAV is dispatched to collect information of ground Sensor Nodes (SNs). The information freshness is measured by the Age of Information (AoI) of each SN, which is defined as the sum of the SN’s data uploading time and the UAV’s flight time after leaving this SN. Two optimization problems of age-optimal data collection are formulated to minimize the SNs’ maximal AoI and average AoI, respectively. An iterative SN association and trajectory planning policy is proposed to seek the age-optimal solutions via an iterative two-step procedure. Firstly, SN association is performed based on the affinity propagation clustering method with an appropriate weight to find a set of data Collection Points (CPs) at which the UAV hovers to collect data and schedules which SNs to upload in what order. Based on this result, trajectory planning is performed to find the max-AoI-optimal and ave-AoI-optimal trajectories of the UAV along the CPs using dynamic programming or genetic algorithm. With the optimized clustering weight, the proposed scheme can always strike a balance between the SNs’ uploading time and the UAV’s flight time in various scenarios. Simulation results show that the proposed strategy can improve the freshness of information collected from all the SNs.

Synthetic di- or multimetallic complexes bearing NxHy nitrogenous ligands in a sulfur-rich coordination environment have attracted considerable attention due to their importance in evaluating the complex mechanism of biological nitrogen fixation. Herein, we report a series of thiolate-bridged dicobalt NxHy species obtained by treatment of CoIIICoIII precursor with hydrazine and its substituted derivatives at ambient temperature. Remarkably, when the substituent is the cyclohexyl group, the resulting species can interconvert through different pathways. This Co2S2 skeleton provides a new model system for obtaining valuable information about the early N2Hx-bound intermediate species during the catalytic cycle of nitrogenase.

Lead-free (1-x)BiFeO3-xBa1-ySryTiO3 (0 ≤ x ≤ 0.4, 0.0 ≤ y ≤ 0.8) (BF-BST) ceramics were fabricated with the conventional solid-state reaction method. The structural, piezoelectric, multiferroic and magnetoelectric properties have been investigated for these BF-BST solid solutions, especially for the samples near the morphotropic phase boundaries (MPB). Structural analysis shows a coexistence of rhombohedral (R) and tetragonal (T) phases in all the MPB samples, in which the lattice distortion of R and T phases increases overall and decreases, respectively, with increasing y. All the MPB samples show multiferroicity and magnetoelectric effect at room temperature. Both the ferroelectricity and piezoelectricity are found to decrease with increasing y in the MPB samples. It is revealed that high T distortion and low R distortion should contribute dominantly to the high piezoelectricity near MPB in BF-BST solid solutions. These results suggest a possible new strategy for designing high-performance piezoelectric ceramics and also the important role of MPB in the improvement of multiferroicity.

Negative thermal expansion (NTE) materials can compensate for the coefficient of thermal expansion (CTE) of normal metals. Currently, it is challenging to prepare NTE/metal composites facing the practical demands. We report the tunable CTEs between –0.39 and 6.19 ppm/K around room temperature in Zn/Si/Zn0.75Sn0.2Mn0.05NMn3 composites. The low-melting Zn acts as the adhesive, while Zn0.75Sn0.2Mn0.05NMn3 is the CTE compensator. Moreover, the composites have high compression strength (225 MPa) and thermal conductivity (52 W/K m), showing great potentials as electronic thermal management materials. Our results suggest an effective way to realize low-CTE composites with excellent performance based on NTE compounds.

A preliminary phytochemical investigation of the stems of the endangered plant Ulmus elongata led to the isolation of a new coumarin derivative (named ulmuselactone A, 1) and eight known compounds (2-9). The new structure was elucidated by detailed analysis of comprehensive spectroscopic methods, and its absolute configuration was established by comparing experimental and calculated electronic circular dichroism (ECD) spectra. The isolated compounds were evaluated for their antibacterial activities.

Barocaloric (BC) materials are a type of promising solid-state refrigerant that can be used in future refrigerators. Besides the routine pressure-driven lattice entropy change, spin or polar degrees of freedom often make considerable contributions. Relatively, little attention has been paid to the electronic contribution. Here we demonstrate a sizable electronic entropy change under pressure in hexagonal Ni1−xFexS due to the remarkable modification of its electronic structure. Accordingly, the total entropy change reaches 52.8 J kg−1 K−1 under only 100 MPa, which places Ni1−xFexS among the giant BC materials. Again, because of the electronic contribution, the thermal conductivity of Ni1−xFexS is higher than the reported values of other giant BC materials, which can boost the cooling efficiency. Our work would inspire the study of the giant BC effect with good thermal conductance in a wide range of electronic phase transition materials.

We report an unambiguous observation of a room temperature (RT) converse magnetoelectric effect (CME) in ternary BiFeO3-based systems near a morphotropic phase boundary (MPB). The results of in situ XRD diffraction at different applied electric fields reveal that the lattice distortion and phase transitions dominate the RT CME in the samples near the MPB. Our results provide an experimental proof and an explanation for the electric-field control of the magnetism effect obtained at the MPB, which may provide an effective way to design multiferroics for potential applications in magnetoelectric devices with low power consumption.

A joint phytochemical investigation on the MeOH extracts of the twigs and needles of two endangered Pinaceae plants endemic to the Chinese Qinling Mountains, Picea neoveitchii (an evergreen spruce) and Larix potaninii var. chinensis (a deciduous larch), led to the isolation and characterization of 34 and 24 structurally diverse terpenoids, respectively. Among them, seven are previously undescribed, including a picane-type [i.e., 14(13 → 12)abeo-12αH-serratane] (neoveitchin A) and a serratane-type (neoveitchin B) triterpenoids, and an abietane-type (neoveitchin C) as well as four labdane-type (potalarxins A-D) diterpenoids. Their structures and absolute configurations were established by extensive spectroscopic methods and/or X-ray diffraction analyses. All isolates were evaluated for their inhibitory activities against the human protein tyrosine phosphatase 1B (PTP1B). Serrat-14-en-3α,21β-diol, betulinic acid, 3β-hydroxy-11-ursen-13(28)-olide, ursolic acid, and oleanolic acid were found to have considerable inhibitory effects against PTP1B, with IC

Thermal diodes, which allow heat flow in one direction but prohibit it in the reverse direction, are fundamental for thermal manipulation. Here, we report the construction of a thermal diode consisting of ${\mathrm{Ni}}_{0.85}{\mathrm{Fe}}_{0.15}\mathrm{S}$ (bonded with 10 wt % silver) and alumina. A high rectification factor \ensuremath{\gamma} of 1.51 is achieved with a relatively small temperature bias of 97 K near room temperature, indicating great potential applications in the field of nonlinear thermal control. The excellent rectification effect is attributed to the high contrast change in thermal conductivity of ${\mathrm{Ni}}_{0.85}{\mathrm{Fe}}_{0.15}\mathrm{S}$. In addition, we demonstrate that the maximum thermal rectification ratio is strongly dependent on the cold-terminal temperature of the thermal diode, the length ratio between the two segments, and the steepness of the first-order phase transition of ${\mathrm{Ni}}_{0.85}{\mathrm{Fe}}_{0.15}\mathrm{S}$.

We present the observation of the peculiar antiferroelectric (AFE)-like behavior, characterized by the polarization-electric field ( P − E ) double hysteresis loops and zero remnant polarization ( P r ), in the ferroelectric (FE) Cr-doped YMnO 3 (YMCO) single crystals. The AFE-like behavior in YMCO is in sharp contrast with the FE P − E single loop with high P r in the undoped YMnO 3 (YMO). The topological cloverleaf domains with ferroelectricity are observed in both YMO and YMCO. It is revealed unambiguously that the AFE-like behavior in YMCO arises from the Cr-substitution induced domain pattern transition from type-II with nonzero net macroscopic polarization to type-I with zero net polarization, as well as the recoverable type-I domain pattern after electric field sweeping. In addition, it is found that both the recoverable energy density and energy storage efficiency are significantly enhanced due to the AFE-like behavior in YMCO compared to YMO. Our results suggest for the first time that, in addition to the mechanism of the antiparallel arrangement of adjacent electric dipoles, the AFE-like behavior can be also achieved by domain engineering in a FE, which provides a possible new strategy to obtain high energy storage performance.

Two-dimensional MXenes (such as Ti2C, V2C, Nb2C, Ti3C2, and Nb4C3) have shown enormous potential in lithium ion storage, and the exploration of new and/or high- performance MXene-based lithium ion storage materials is an active field. This present work demonstrates the synthesis of two-dimensional vanadium carbide V4C3 MXene by selectively etching Al layers from V4AlC3 in hydrofluoric acid at 55 °C. Large specific surface (∼52.1 m2 g−1) and interlayer spacing (∼0.466 nm) can be obtained in V4C3 MXene via adding sufficient ball-milling treatment on precursor V4AlC3, which is benefit for lithium ion storage. As an anode material for lithium ion batteries, it shows high capacity as well as good rate capability and cycling performance. More specifically, V4C3 delivers a high specific capacity of 225 mAh g−1 after 300 charge/discharge cycles at a current density of 0.1 A g−1, and 125 mAh g−1 at 1 A g−1. This work provides another potential MXene-based lithium ion storage material and is expected to inspire more explorations of high-performance MXene-based electrode materials for lithium ion batteries and capacitors.

An excitonic insulating (EI) state is a fantastic correlated electron phase in condensed matter physics, driven by screened electron–hole interaction. Ta2NiSe5 is an excitonic insulator with a crit...

Two-dimensional (2D) MXenes such as Ti3C2, Ti2C, Mo2C, and Mo1.33C have shown excellent electrochemical performances as supercapacitor electrodes, and the exploration of new and/or high-capacity MXene-based supercapacitor electrode materials is an active field. In this work, 2D multi-layered V4C3 MXene has been synthesized by selectively etching Al from V4AlC3 and it shows a high capacitance of 209 F g−1 at 2 mV s−1, good rate performance, and stable long cyclic performance with capacitance retention rate of 97.23% after 10000 cycles at 10 A g−1 in 1 M H2SO4. Importantly, the pseudocapacitance (∼100.1 F g−1) accounts for about 37% of the total capacity (∼268.5 F g−1) for V4C3 MXene electrode. Therefore, the high specific capacitance of V4C3 MXene is not only due to their wide interlayer spacing (∼0.466 nm), large specific surface areas (∼31.35 m2 g−1) and pore volumes (∼0.047 cm3 g−1), and good hydrophilicity but also attributed to the abundant valence states of vanadium (+2, +3, and +4). The high rate performance and excellent cycling stability of V4C3 MXene electrodes are mainly attributed to the high electronic conductivity (1137 S m−1 at 300 K). The present work provides another promising MXene-based supercapacitor electrode material.

The large volumetric contraction effect presented by MnM’X (M’ = Co, Ni; X = Ge, Si) during the martensitic (MA) transformation displays their potential applications in negative thermal expansion (NTE) field. In this work, we report the giant antiferromagnetic (AFM) NTE in (MnNiGe)1-x(MnCoSn)x (0.02 ≤ x ≤ 0.1) compounds. When x = 0.02, 0.04, 0.06 and 0.1, their average linear NTE coefficients reach −48 ppm/K (220 K - 332 K), −96 ppm/K (174 K-280 K), −92 ppm/K (116 K-220 K) and −35 ppm/K (75 K-130 K), respectively. Moreover, the magnetization shows a descending tendency with increasing x from 0.02 to 0.1, which can be attributed to the more-antiparallel AFM ground state, suggesting their feasible applications in the magnetic environment.

MAX-phase compounds with layered structure have been investigated extensively due to their excellent metallic and ceramic properties. Among them, Cr2GaC and Cr2GaN possess the same crystal structure and similar electronic structure, whereas Cr2GaN undergoes a spin-density-wave transition around 170 K but Cr2GaC is Pauli paramagnetism without any magnetic transition. To understand what make these happen, we studied the crystal structure between 300 and 35 K for both Cr2GaC and Cr2GaN. As the temperature decreases, the lattice constants (both a and c) decline monotonically in Cr2GaC, while an abnormal negative thermal expansion of c axis was observed below 170 K in Cr2GaN. The increase of c/a induced by abnormal increase of c leads to the enhancement of localization of Cr2N plane and causes more Cr-3d electrons confinement in Cr2N plane of Cr2GaN. This further facilitates the reconstruction of density of states near the Fermi surface and even forms the Fermi surface nesting, resulting in the spin-density-wave transition as well as the abrupt changes of resistivity, specific heat, and density of carriers around 170 K in Cr2GaN.

Through successive one-electron reduction processes, a coordinatively unsaturated thiolate-bridged CoIICoII complex [Cp*Co(μ-SEt)2CoCp*] (1) was facilely generated in high yield. In the presence of O2, complex 1 can smoothly take up CO2, and then install it at the Co2S2 scaffold in the form of a carbonate bridge to give complex [Cp*Co(μ-SEt)2(μ–η1:η1-CO3)CoCp*] (2). The carbonate group plays the role of a robust bridging ligand in a rare μ–η1:η1 fashion, which remains unchanged even upon treatment by protonation to bicarbonate or methylation to a carbonate monoester. Furthermore, in the presence of a one-electron oxidant Fc·PF6, this Co2S2 platform can facilitate CO2 functionalization with primary alcohols or amines by the C–O or C–N bond formation process. The resultant deprotonated carbonate monoester or carbamate is bridged between the two cobalt centers to generate complexes [Cp*Co(μ-SEt)2(μ–η1:η1-O2COR)CoCp*][PF6] (5a[PF6], R = Me; 5b[PF6], R = Et) or [Cp*Co(μ-SEt)2(μ–η1:η1-O2CNR1R2)CoCp*][PF6] (6a[PF6], R1 = H, R2 = nBu; 6b[PF6], R1 = H, R2 = iPr; 6c[PF6], R1 = Et, R2 = Et), and serve as a chelating ligand through the two oxygen atoms. This system thus illustrates a new dinuclear cobalt complex for CO2 activation and transformation under oxidised conditions by the synergistic effect.