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Low permittivity microwave dielectric ceramics (MWDCs) are attracting great interest because of their promising applications in the new era of 5G and IoT. Although theoretical rules and computational methods are of practical use for permittivity prediction, unsatisfactory predictability and universality impede rational design of new high-performance materials. In this work, based on a dataset of 254 single-phase microwave dielectric ceramics (MWDCs), machine learning (ML) methods established a high accuracy model for permittivity prediction and gave insights of quantitative chemistry/structure-property relationships. We employed five commonly-used algorithms, and introduced 32 intrinsic chemical, structural and thermodynamic features which have correlations with permittivity for modeling. Machine learning results help identify the permittivity decisive factors, including polarizability per unit volume, average bond length, and average cell volume per atom. The feature-property relationships were discussed. The optimal model constructed by support vector regression with radial basis function kernel was validated its superior predictability and generalization by verification dataset. Low permittivity material systems were screened from a dataset of ∼3300 materials without reported microwave permittivity by high-throughput prediction using optimal model. Several predicted low permittivity ceramics were synthesized, and the experimental results agree well with ML prediction, which confirmed the reliability of the prediction model.

4CuO–TiO2–2Nb2O5 (CTN)-modified (K0.48Na0.52)0.97Li0.03NbO3- 0.03CaZrO3 (KNLNCZ-xCTN, x = 0.0, 0.5, 1.0, 1.5) lead-free piezoelectric ceramics were prepared using a conventional solid-state method. It is found that the addition of CTN could broaden the sintering window and suppress the abnormal grain growth of the sintered ceramics. The XPS results revealed that the Cu ions seem to be in the monovalent state at the ceramics inside and the Cu+ ions couldn't induce the hardening effect due to the equivalent replacement of Cu+ ions for Na+ ions. As a result, the well-saturated P-E loops and improved piezoelectric properties were obtained in the samples and the KNLNCZ-1.0CTN ceramic showed the optimal values with d33 = 131 pC/N, d 33 ∗ = 303 pm/V, kp = 0.43, and tanδ = 0.009. Meanwhile, the good temperature stability of the strain in the range of 20–80 °C was also achieved.

The aim of the present paper is to consider a fully elastic beam equation with left-end fixed and right-end simply supported, i.e.,u4t=ft,ut,u′t,u″t,u‴t, t∈0,1u0=u′0=u1=u″1=0, wheref:0,1×ℝ4⟶ℝis a continuous function. By applying Leray–Schauder fixed point theorem of the completely continuous operator, the existence and uniqueness of solutions are obtained under the conditions that the nonlinear function satisfies the linear growth and superlinear growth. For the case of superlinear growth, a Nagumo-type condition is introduced to limit thatft,x0,x1,x2,x3is quadratical growth onx3at most.

Two-dimensional (2D) metal oxides and chalcogenides (MOs & MCs) have been regarded as a new class of promising electro- and photocatalysts for many important chemical reactions such as hydrogen evolution reaction, CO2 reduction reaction and N2 reduction reaction in virtue of their outstanding physicochemical properties. However, pristine 2D MOs & MCs generally show the relatively poor catalytic performances due to the low electrical conductivity, few active sites and fast charge recombination. Therefore, considerable efforts have been devoted to engineering 2D MOs & MCs by rational structural design and chemical modification to further improve the catalytic activities. Herein, we comprehensively review the recent advances for engineering technologies of 2D MOs & MCs, which are mainly focused on the intercalation, doping, defects creation, facet design and compositing with functional materials. Meanwhile, the relationship between morphological, physicochemical, electronic, and optical properties of 2D MOs & MCs and their electro- and photocatalytic performances is also systematically discussed. Finally, we further give the prospect and challenge of the field and possible future research directions, aiming to inspire more research for achieving high-performance 2D MOs & MCs catalysts in energy storage and conversion fields.

Metal matrix diamond composites (MMDC) started from the pre-alloyed powders with the addition of different concentration of Ti3AlC2 MAX phase were prepared via microwave assisted sintering (MAS) method. The microstructure of samples was examined by SEM, EDS and XRD characterization methods. The mechanical properties including relative density, abrasive ratio, impact toughness, hardness, elastic modulus and bending strength were also analyzed to investigate the contribution of the additive of Ti3AlC2. The results demonstrate that Ti3AlC2 additive is beneficial for promoting the mechanical properties and the optimized Ti3AlC2 addition concentration is 25 wt %. The enhancement effect of the comprehensive mechanical properties could be due to the in-situ decomposition of Ti3AlC2 induced by diamond and the generated Al to stuff porosity and then conducive to densification of the sintered structure. Simultaneously, Al element reacts with diamond abrasive to produce Al4C3 transition layer on the diamond surface, which improves the bonding force between the diamond and the matrix for the MMDC sample. The advantages of microwave heating and the pre-alloying of raw powder can avoid the graphitization behavior of internal diamond abrasive owning to the relatively low sintering temperature. The potential sintering mechanism of the pre-alloyed diamond composites by the addition of Ti3AlC2 in the microwave field was also discussed.

Domesticates are an excellent model for understanding biological consequences of rapid climate change. Maize (Zea mays ssp. mays) was domesticated from a tropical grass yet is widespread across temperate regions today. We investigate the biological basis of temperate adaptation in diverse structured nested association mapping (NAM) populations from China, Europe (Dent and Flint) and the United States as well as in the Ames inbred diversity panel, using days to flowering as a proxy. Using cross-population prediction, where high prediction accuracy derives from overall genomic relatedness, shared genetic architecture, and sufficient diversity in the training population, we identify patterns in predictive ability across the five populations. To identify the source of temperate adapted alleles in these populations, we predict top associated genome-wide association study (GWAS) identified loci in a Random Forest Classifier using independent temperate–tropical North American populations based on lines selected from Hapmap3 as predictors. We find that North American populations are well predicted (AUC equals 0.89 and 0.85 for Ames and USNAM, respectively), European populations somewhat well predicted (AUC equals 0.59 and 0.67 for the Dent and Flint panels, respectively) and that the Chinese population is not predicted well at all (AUC is 0.47), suggesting an independent adaptation process for early flowering in China. Multiple adaptations for the complex trait days to flowering in maize provide hope for similar natural systems under climate change.

Structure and dielectric properties of gillespite-type ceramics ACuSi4O10 (A = Ca, Sr, Ba) were investigated by crystal structure refinement, far-infrared reflectivity spectroscopy, and microwave dielectric measurements. A series of (CaxSr1-x)CuSi4O10 (0 < x < 1) ceramics with relative permittivities of 5.70-5.82, Q × f values of 20391-48794 GHz (@ ∼ 13.5 GHz), and τf of -46.3 to -38.9 ppm/°C were synthesized. By Ca2+ substitution for Sr2+ at the A-site, the rigid double-layered copper silicate framework remains stable, resulting in the nearly unchanged relative permittivity, while the [(Ca,Sr)O8] dodecahedron undergoes shrinkage and distortion, which is correlated to the changes in the Q × f and τf values. The normalized bond valence sums indicate that almost all ions are rattling, weakening the bond strengths and enlarging the molecular dielectric polarizability. The fitting of far-infrared reflectivity spectra reveals that the local structure changes suppress the intermediate and low-frequency vibrational modes significantly and improves the contribution from electronic polarization to permittivity. Symmetry breaking of the [(Ca,Sr)O8] dodecahedron conforms to the elevated restoring forces acting on the ions and improves the τf value. The large span in Q × f value may have intricate correlations to local structure changes and defects. Machine learning methods were introduced to explore the decisive structural factors for the Q × f value. A Q × f value prediction model correlated with the A-O2 bond length and the variance of A-O bond lengths was established. The Q × f values of isostructural (BaySr1-y)CuSi4O10 ceramics were predicted and verified by experiments.

Synthesizing two dimensional (2D) nanomaterials with controlled sub-nanometer thicknesses from non-layered crystals presents both significant challenges and vast opportunities. However, mechanical exfoliation techniques and physical/wet chemical deposition processes are widely disadvantageous for applicability to non-layered structures. Here we have utilized a simple self-limiting approach to prepare large sheets of 2D zinc oxide (ZnO) at the metal-melt/air interface. These ultra-thin sheets demonstrated highly crystalline hexagonal structures. The specific ZnO hexagonal sheet thickness and its interaction with the substrate were found to have a critical impact on d33. This unusual structure resulted in an exceptionally high out of plane piezoelectricity, yielding a giant value of 80 ± 0.8 pm/V at 2.5 unit-cell thickness for d33, which is 5 Zn-O layers in the wurtzite crystal. This out of plane piezoelectricity value is approximately 8 times larger than that of the value for bulk ZnO. Theoretical studies were carried out to elucidate the impact of the thickness and the substrate’s role on the polarization of the layers. The existence of a large piezoelectricity offered by the synergy of the substrate and specific thickness of ultrathin films offers the opportunity for other groups of potentially piezoelectric materials to be explored.

This paper investigates the Cauchy problem to a class of stochastic non-autonomous evolution equations of parabolic type governed by noncompact evolution families in Hilbert spaces. Combining the theory of evolution families, the fixed point theorem with respect to convex-power condensing operator and a new estimation technique of the measure of noncompactness, we established some new existence results of mild solutions under the situation that the nonlinear function satisfy some appropriate local growth condition and a noncompactness measure condition. Our results generalize and improve some previous results on this topic, since the strong restriction on the constants in the condition of noncompactness measure is completely deleted, and also the condition of uniformly continuity of the nonlinearity is not required. At last, as samples of applications, we consider the Cauchy problem to a class of stochastic non-autonomous partial differential equation of parabolic type.

Post-annealing in a weak oxidative atmosphere (a partial pressure of oxygen P(O2) = 1 × 10-6 MPa in high purity N2) was applied to the reductive-atmosphere-sintered (K0.48Na0.52)NbO3 lead-free piezoceramics. Structural characterization indicated that the Nb–O bond length and local structure order degree of the (K0.48Na0.52)NbO3 ceramics increased after post-annealing. The dielectric and impedance spectra analysis revealed that the oxygen vacancies could be compensated after the post-annealing process. The piezoelectric performances of the KNN ceramics post-annealed at 900 °C for 4 h were comparable with that of counterpart sintered in the air. These results indicate that the post-annealing treatment may provide a prospective approach for the fabrication of base metal electrode-cofired KNN multilayer piezoelectric devices.

The emergence of piezoelectric properties in two-dimensional (2D) layered transition metal dichalcogenides (TMDs) has triggered the intensive research on using low dimensional materials for conversion of mechanical stimuli into electrical signals or vice versa. While the bulk intrinsically presents no piezoelectric property, the origin of the piezoelectric responses in their 2D thin planes is ascribed to the loss of centrosymmetry. There are also other categories of 2D layered materials such as post-transition metal dichalcogenides (PTMDs) that might be of interests, which have been confirmed theoretically and are yet to be fully explored experimentally. In this work, we investigate the thickness-dependent piezoelectric responses of 2D tin disulfide (SnS2) nanosheets as a representative of layered PTMDs. The results indicate that the 2D SnS2 nanosheets with a thickness of ∼4 nm present an effective out-of-plane piezoelectric response of 2 ± 0.22 pm/V. Furthermore, the thickness dependence of the piezoelectric behavior at a resonant frequency shows that the piezoelectric coefficient decreases with increasing the thickness of 2D SnS2 nanosheets. Additionally, in reference to periodically poled lithium niobate piezoelectric crystal, the measured effective lateral piezoelectric coefficients at different voltages range from 0.61 to 1.55 pm/V with the average value at ∼1 pm/V. This study expands candidates for new piezoelectric materials in the 2D domain with comparable vertical and lateral coefficients, potentially opening a broader horizon for integration into sensors, actuators, and micro- and nanoelectromechanical systems.

This paper deals with the approximate controllability for a class of fractional stochastic evolution equations with nonlocal initial conditions in a Hilbert space. We delete the compactness condition or Lipschitz condition for nonlocal term appearing in various literatures, and only need to suppose some weak growth condition on the nonlocal term. The discussion is based on the fixed point theorem, diagonal argument and approximation techniques. In the end, an example is presented to illustrate the abstract theory.

In this paper, a wall-adapted anisotropic heat flux model for large eddy simulations of complex engineering applications is proposed. First, the accuracy and physical consistency of the novel heat flux model are testified for turbulent heated channel flows with different fluid properties by comparing with conventional isotropic models. Then, the performance of the model is evaluated in case of more complex heat and fluid flow situations that are in particular relevant for internal combustion engines and engine exhaust systems. For this purpose large eddy simulations of a strongly heated pipe flow, a turbulent inclined jet impinging on a heated solid surface and a backward-facing step flow with heated walls were carried out. It turned out that the proposed heat flux model has the following advantages over existing model formulations: (1) it accounts for variable fluid properties and anisotropic effects in the unresolved temperature scales, (2) no ad-hoc treatments or dynamic procedure are required to obtain the correct near-wall behavior, (3) the formulation is consistent with the second law of thermodynamics, and (4) the model has a similar prediction accuracy and computational effort than conventional isotropic models. In particular, it is shown that the proposed heat flux model is the only model under consideration that is able to predict the direction of subgrid-scale heat fluxes correctly, also under realistic heat and fluid flow conditions in complex engineering applications.

This article deals with the exact controllability for a class of fractional stochastic evolution equations with nonlocal initial conditions in a Hilbert space under the assumption that the semigroup generated by the linear part is noncompact. Our main results are obtained by utilizing stochastic analysis technique, measure of noncompactness and the Mönch fixed point theorem. In the end, an example is presented to illustrate that our theorems guarantee the effectiveness of controllability results in the infinite dimensional spaces.

The Quantougou (QTG) Fauna in central Lanzhou Basin is an important late Mid-Miocene fauna on the northeastern Tibetan Plateau margin, but its numerical age remains a matter of debate. Here, we present a new magnetostratigraphic record for a fluvio-lacustrine section to further constrain the age of the QTG Fauna. Results suggest that the studied section spans from polarity chrons C5Cn.2n to C5n.2n or C5An.1n, with ages of ca. 16.5 Ma to 10 ​Ma or 16.5 Ma to 12 ​Ma. The QTG Fauna is located at the top of polarity chron C5r.3r or C5Ar.2r, which corresponds to an age of 11.7 Ma or 12.8 ​Ma for the fauna. Accordingly, the associated Myocricetodontinae (a subfamily of Gerbillidae, Rodentia) is suggested to have appeared in the Lanzhou Basin at 11.7 ​Ma or 12.8 ​Ma, which is the oldest Myocricetodontinae in East Asia but is still much younger than the ~20 ​Ma appearance of this subfamily in West and South Asia. Our age data support the interpretation that East Asian Myocricetodontinae originated from South Asia. The QTG fauna further suggest a dry and open grassland environment, which is consistent with global cooling after the Mid-Miocene Climatic Optimum.

International audience; The Upper Cretaceous sedimentary sequence at International Ocean Discovery Program Site U1512 in the Ceduna Sub-basin of the Great Australian Bight represents a continuous, > 690 m thick interval of black silty clay and claystone spanning the lower Turonian through Lower Campanian (~10 million years). Sediments were deposited in an elongate, ~E-W oriented, ~2500 km long rift system that developed between Australia and Antarctica with an open-ocean connection to the west and a continental bridge to the east. Site U1512 cores provide a unique, continuous record of Late Cretaceous deposition in the Ceduna Sub-basin on the hanging wall of the Wallaroo Fault Zone. Study of U1512 samples could provide both an important high-latitude, southern hemisphere perspective on climatic evolution during the peak and demise of the Cretaceous hothouse and an offshore record of the sedimentation history in the basin during the Late Cretaceous portion of the Gondwanan breakup. The Upper Cretaceous sequence at Site U1512 is notable for its lithologic uniformity. Burrow-mottled to massive claystone and silty claystone make up the majority of the almost 700 m section, while rare (n = 28) isolated, 2 to 21 cm thick medium to fine sandstone beds are a minor lithology. Macrofossils present include common inoceramids and rare occurrences of other bivalves and ammonites. Microfossils include common occurrences of calcareous nannofossils, agglutinated and calcareous benthic foraminifera, radiolaria and organic-walled dinoflagellate cysts as well as rare small, surface dwelling planktonic foraminifera. Carbonate (

The predicted strong piezoelectricity for monolayers of group IV monochalcogenides, together with their inherent flexibility, makes them likely candidates for developing flexible nanogenerators. Within this group, SnS is a potential choice for such nanogenerators due to its favourable semiconducting properties. To date, access to large-area and highly crystalline monolayer SnS has been challenging due to the presence of strong inter-layer interactions by the lone-pair electrons of S. Here we report single crystal across-the-plane and large-area monolayer SnS synthesis using a liquid metal-based technique. The characterisations confirm the formation of atomically thin SnS with a remarkable carrier mobility of ~35 cm2 V−1 s−1 and piezoelectric coefficient of ~26 pm V−1. Piezoelectric nanogenerators fabricated using the SnS monolayers demonstrate a peak output voltage of ~150 mV at 0.7% strain. The stable and flexible monolayer SnS can be implemented into a variety of systems for efficient energy harvesting., The presence of strong inter-layer interactions has hindered the synthesis efforts towards large-area and highly crystalline monolayer SnS. Here, the authors report synthesis of large-area monolayer SnS using a liquid metal-based technique, and fabricate piezoelectric nano-generators with average peak output voltage of 150 mV at 0.7% strain.

In this work, a large eddy simulation (LES) technique combined with entropy generation analysis (EGA) is employed in order to investigate the complex physics of fuel injection under supercritical c...

Large depression-type lake basins developed during the Late Triassic in the Ordos Basin, and hydrothermal activity at the bottom of these lakes was frequent. Here, we report an example from the Cha...

A deeper understanding of hyperthermal events in the Earth’s history can provide an important scientific basis for understanding and coping with global warming in the Anthropocene. Two types of hyperthermal events are classified based on the characteristics of the carbon isotope excursion (CIE) of the five representative hyperthermal events in the Mesozoic and Cenozoic. The first type is overall characterized by negative CIEs (NCHE) and represented by the Permian-Triassic boundary event (PTB, ~252 Ma), the early Toarcian oceanic anoxic event (TOAE, ~183 Ma), and the Paleocene-Eocene Thermal Maximum event (PETM, ~56 Ma). The second type is overall characterized by positive CIEs (PCHE) and represented by the early Aptian oceanic anoxic event (OAE1a, ~120 Ma) and the latest Cenomanian oceanic anoxic event (OAE2, ~94 Ma). Hyperthermal events of negative CIEs (NCHE), lead to dramatic changes in temperature, sedimentation, and biodiversity. These events caused frequent occurrence of terrestrial wildfires, extreme droughts, acid rain, destruction of ozone layer, metal poisoning (such as mercury), changes in terrestrial water system, and carbonate platform demise, ocean acidification, ocean anoxia in marine settings, and various degree extinction of terrestrial and marine life, especially in shallow marine. In contrast, hyperthermal events of positive CIEs (PCHE), result in rapid warming of seawater and widespread oceanic anoxia, large-scale burial of organic matter and associated black shale deposition, which exerted more significant impacts on deep-water marine life, but little impacts on shallow sea and terrestrial life. While PCHEs were triggered by volcanism associated with LIPs in deep-sea environment, the released heat and nutrient were buffered by seawater due to their eruption in the deep sea, thus exerted more significant impacts on deep-marine biota than on shallow marine and terrestrial biota. This work enriches the study of hyperthermal events in geological history, not only for the understanding of hyperthermal events themselves, large igneous provinces, marine and terrestrial environment changes, mass extinctions, but also for providing a new method to identify the types of hyperthermal events and the inference of their driving mechanism based on the characteristics of carbon isotopic excursions and geological records.

The Li–Al–Si glass-ceramics were prepared by conventional glass-ceramic fabrication method. The influences of Na2O content on the sintering property, microstructure, and coefficient of thermal expansion were investigated. The results show that the coefficient of thermal expansion of LAS glass-ceramics can be tailored to match that of silicon by the addition of Na2O content. Na2O has a remarkable influence on the crystallinity of Li–Al–Si glass-ceramic. The coefficient of thermal expansion of Li–Al–Si glass-ceramic is thus tunable between that of glass phase and crystal phase. The Si–O bond length change in stretch vibration modes introduced by Na2O also contributes to the variation of coefficient of thermal expansion of the Li–Al–Si glass-ceramics. The coefficient of thermal expansion of the Li–Al–Si glass-ceramic with 1.5 wt% Na2O addition is about +3.34 ppm/°C at 350 °C and shows a good compatibility to that of silicon in a wide temperature range, which makes it a promising candidate for anodic bondable low temperature co-fired ceramic substrate applications.

For the development of high-performance gas sensors, ultrafast response and high selectivity are critical requirements for many practical applications. An alternative strategy is to employ hierarchical nanostructured materials in gas sensors. In this work, we report newly synthesized TiO2 hexagonal nanosheets with a hierarchical porous structure, which demonstrate an ultrafast gas response and high selectivity toward acetone vapor for the first time. A simple one-step annealing process to prepare hierarchical TiO2 nanosheets derived from layered TiSe2 nanosheet templates is reported. The hierarchical structure interlaced with anatase TiO2 nanosheets showed an open porous characteristic. The average pore size was about 20 nm examined using a high-resolution TEM. The gas sensing properties toward acetone vapor of the novel hierarchical structured TiO2 nanosheets were characterized in detail including optimal operation temperature, sensitivity, selectivity, response/recovery time, and long-term stability. The gas sensing response and recovery times were 0.75 s and 0.5 s, respectively. We attribute these superior response properties to its unique hierarchical pore structure with a high specific surface area. The results show great potential for acetone vapor detection, particularly in dynamic ultrafast monitoring by using the synthesized hierarchical structured TiO2 nanosheets.

Antiferroelectric materials with higher electric field, reduced energy dissipation and lower remanent polarization generally display excellent energy storage performance. In this work, Pb0.98La0.02(HfxSn1−x)0.995O3 lead-based antiferroelectric ceramics were synthesized by a rolling process. It is revealed that the inhomogeneous distribution of Sn4+ can disorder the local structure, which is responsible for the slim hysteresis loops. Superior energy storage performance (recoverable energy density Wrec = 7.63 J cm−3, η = 94% at an electric field of 380 kV cm−1) with excellent thermal stability (20–120 °C) were achieved in Pb0.98La0.02(Hf0.45Sn0.55)0.995O3 ceramic. In addition, it also shows a notable discharge current density of 1430 A cm−2 and high level of power density of 193 MW cm−3 with a fast discharge speed (112 ns discharge period), which greatly promote the application of this series of component materials in energy storage applications.

Through systematic optimization studies of Li and Al co-doped ZnO ceramics we demonstrate that colossal permittivity with low dielectric loss (er = 9862 and tan δ = 0.159 at the frequency of 1 kHz) at room temperature can be achieved in Zn0.99(Li0.1, Al0.2)0.033O. The colossal dielectric constant (CDC) and low dielectric loss in this ceramic have relatively good frequency and temperature stability. Annealing the ceramic at 900 °C in oxygen leads to the drop of er to 2250 but the dielectric loss remains at ∼0.10. Dielectric spectrum analysis shows that the CDC is associated with two relaxation processes. One of these process vanishes and the other one persists after annealing, suggesting that P1 is associated with oxygen-deficient defects. For samples exhibiting CDC, ac conductivity study revealed correlated barrier hopping between defect states in the band gap. A model involving these defects as the electron pinned defect dipole is proposed. The experimental dielectric data are well described by this model using Kirkwood's theory and Kramer–Kronig transformation.

Room temperature electronic nose sensor arrays are of interest to numerous sensing applications as they can detect multiple gases selectively. One prerequisite in a sensor array is the absence of the heating element, which can considerably reduce design complexity and power consumption while providing multiple gas detection on one substrate. In this work, we show the fabrication of an electronic nose that implements an array of two Schottky diode and two heterojunction diode hydrogen sensors using Ta2O5 and WO3 on the same substrate. The gas sensitive layers were fabricated via RF sputtering and 500°C post-annealing. We demonstrate room temperature sensitivity with fast hydrogen and hydrocarbon gas detection in the order of seconds under different biases. The device exhibits unique response when exposed to H2, CH4, C2H6 and C3H8 gases sequentially. The effects of humidity on each sensor were also examined.

In this paper, we investigate the existence of the extremal solutions for a class of impulsive fractional integro-differential equation with order $$1< \alpha < 2$$, combine upper and lower solution method with the theory of $$(\alpha ,\beta )$$-resolvent family, a series of results about the solutions to such differential equations is obtained. The results improve and extend some relevant results in ordinary differential equations and partial differential equations. Finally, an example is given to illustrate the feasibility of our results.

This paper is concerned with the existence of extremal mild solutions for Hilfer fractional evolution equations with nonlocal conditions in an ordered Banach spaceE. By employing the method of lower and upper solutions, the measure of noncompactness, and Sadovskii’s fixed point theorem, we obtain the existence of extremal mild solutions for Hilfer fractional evolution equations with noncompact semigroups. Finally, an example is provided to illustrate the feasibility of our main results.

We consider the existence of a mild solution of supdiffusion equations and obtain some results under some growth and noncompactness conditions of nonlinearity without coefficient restriction, and some new results for Ulam-Hyers-Rassias stability are obtained.

Li–Al–B–Si–O (LABS) glass-ceramics with a sintering temperature of 600 °C were studied for ultra-low temperature co-fired ceramics (ULTCC) applications. The crystal phase of LABS glass-ceramics is dendritic β-spodumene. The permittivity and dielectric loss of LABS glass-ceramics are e r = 5.8 and tg δ = 1.3 × 10 −3 at 10 MHz, respectively. The coefficient of thermal expansion (CTE) of LABS glass-ceramics is 3.23 ppm/°C, which is close to that of silicon. The dielectric and thermal properties of LABS glass-ceramics are closely correlated to the degree of its crystallization. The permittivity decreases continually while the dielectric loss decreases first and slightly increases with the increasing of crystallization of β-spodumene. The CTE of LABS glass-ceramics decreases as β-spodumene crystallized from LABS glass. The crystallization kinetic and mechanism of LABS glass-ceramics indicate that the β-spodumene crystallizes in a two-dimensional interfacial growth mechanism due to the migration of Li-ions. The diffusion coefficients derived from energy-dispersive X-ray spectroscopy (EDS) results indicated that both Al and Ag electrodes have good compatibilities with ULTCC tapes, which could reduce the cost of multilayer electro-ceramic devices dramatically by using the ULTCC and base metallization.

The terahertz (THz) dielectric constant ( e r ' ) and dielectric loss tangent ( tan δ ) of the commercial LTCC materials (Ferro A6M and DuPont 951), Al2O3 (ceramic and single crystal), AlN and β-Si3N4 ceramics were measured using a vector network analyzer (VNA) over the frequency range of 140–220 GHz and a time-domain spectrometer (TDS) from 0.2 to 1.0 THz. The results from the two instruments are compared with the literature and show good agreement and consistency. For Ferro A6M, e r ' = 6.06, tan δ = 0.012 at 1.0 THz. For DuPont 951, e r ' = 7.67, tan δ = 0.097 at 1.0 THz. For Al2O3 ceramic and single crystal, the measured THz dielectric properties are consistent with the reported works. The dielectric constant of AlN ( e r ' = 8.85) and β-Si3N4 ( e r ' = 8.41) ceramics in the THz region is a little lower than those reported for the MHz to GHz region. These results provide valuable and much needed reference information for device designers and material scientists.

In this paper, we concern with the existence of mild solution to nonlocal initial value problem for nonlinear Sobolev-type impulsive evolution equations with Hilfer fractional derivative which generalized the Riemann–Liouville fractional derivative. At first, we establish an equivalent integral equation for our main problem. Second, by means of the properties of Hilfer fractional calculus, combining measure of noncompactness with the fixed-point methods, we obtain the existence results of mild solutions with two new characteristic solution operators. The results we obtained are new and more general to known results. At last, an example is provided to illustrate the results.

In this paper, we used Henstock–Kurzweil–Pettis integral instead of classical integrals. Using fixed point theorem and weak measure of noncompactness, we study the existence of weak solutions of boundary value problem for fractional integro-differential equations in Banach spaces. Our results generalize some known results. Finally, an example is given to demonstrate the feasibility of our conclusions.

Genetic relationships between the phenotypic means and plasticities of kernel size and weight revealed the common genetic control of these traits in maize. Kernel size and weight are crucial components of grain yield in maize, and phenotypic plasticity in these traits facilitates adaptations to changing environments. Elucidating the genetic architecture of the mean phenotypic values and plasticities of kernel size and weight may be essential for breeding climate-robust maize varieties. Here, a maize nested association mapping (CN-NAM) population and association panel were grown in different environments. A joint linkage analysis and genome-wide association mapping were performed for five kernel size and weight phenotypic traits and two phenotypic plasticity measures. The mean phenotypes and plasticities were significantly correlated. The overall results of quantitative trait locus (QTL) and candidate gene analyses indicated moderate and high levels of common genetic control for the two traits. Furthermore, the mean phenotypes or plasticities of the hundred-kernel weight and volume were commonly regulated to a high degree. One pleiotropic locus on chromosome 10 simultaneously controlled the mean phenotypic values and plasticities of kernel size and weight. Therefore, the plasticity of kernel size and weight might be indirectly selected during maize breeding; however, selecting for high or low plasticity in combination with high or low mean phenotypic values of kernel size and weight traits may be difficult.

Shanyangzhai Cave, located in Hebei Province, North China, has yielded a large number of snake bones dated back to the late middle Pleistocene and late Pleistocene. These snakes are represented by ...

The CaTi(1-x)(Al0.5Nb0.5)xSiO5(0 ≤ x ≤ 0.1) ceramics were prepared by the conventional solid-state method. Al and Nb co-doping improved the high temperature stability of the CaTiSiO5 material and no obvious phase transition was found at temperature up to 623 K for x ≥ 0.03. A dielectric constant of 53, dielectric loss of 0.001, resistivity of 8.5 × 1013 Ω cm, and breakdown strength of 1064.7 kV/cm was obtained for the CaTi0.97(Al0.5Nb0.5)0.03SiO5 ceramics at room-temperature. The dielectric constant is stable over a wide temperature range and a resistivity of 9.0 × 1010 Ω cm could still be achieved up to 573 K. The P-E loops measurements showed that energy storage efficiencies of 96% and 88.6% could be obtained at room-temperature and 453 K, respectively, for the CaTi0.97(Al0.5Nb0.5)0.03SiO5 ceramics. The excellent dielectric properties at elevated temperature indicate that titanite based ceramics stabilized by Al and Nb co-doping could be promising candidates for high temperature ceramic capacitors application.

Microperoxidase-11 (MP-11) has been widely used in enzymatic reactions. Further improvement of its performance requires a better charge transfer and more exposure of its active site in the enzymatic conversions, which can be achieved by immobilisation of MP-11 into functional materials. However, conventional immobilisation techniques always suffer from non-specific and uncontrolled weak interactions and energy level of two entities in the hybrid is not perfectly matched, thus resulting in limited improvement of the system. In this work, a hybrid material of layered MoO3 and MP-11 was synthesised by a self-assembly technique through a covalent interaction. Physicochemical characterisation indicated that there is a charge transfer from MP-11 to MoO3 and a covalent bond is formed in the hybrid. A notable enhancement of biocatalysis and photocurrent conversion were observed in the studies, which are due to a synergistic effect and band alignment of the two entities in the hybrid. The superior combined properties provide a great opportunity for developing high performance enzymatic conversion systems.

Three kinds of borosilicate glass-ceramics Low temperature co-fired ceramics (LTCC) substrate materials, Ca-B-Si-O (CBS), Ca-Al-B-Si-O (CABS), and Ca-Mg-B-Si-O (CMBS), have been prepared, and the biocompatibility of these materials was evaluated. Compared with CBS and CMBS samples, the CABS sample presented the lowest crystallinity and dissolution in the bioleaching experiments. The direct and indirect cell culturing results showed that the CABS sample also possessed the best biocompatibility to the bone mesenchymal stem cells (BMSCs) due to its good bio-stability and surface micro-pore structure. The effects of surface topography and released ions on cytocompatibility were analyzed. These results were expected to offer some guideline information for developing LTCC substrate materials used in the microfluidic biosensors for the future biological and medical application.

The chronological framework of late Pleistocene and Holocene transgressional strata along the Fujian coasts in southeastern China were examined using new 14C dates, OSL ages, and diatom data from cores drilled in Longhai. This location was chosen because previous studies in the region have interpreted the occurrence of MIS3, MIS2, and Holocene transgressions. Our study, and a critical review of previous studies, show that 14C dates of bulk samples from coastal areas tend to be erroneously older than the depositional age due to enhanced input of old carbon via erosion of Mesozoic basement rocks from mountainous inlands. Also, OSL dates of deltaic and fluvial sediments either vary widely due to unsuitable luminescence properties of quartz grains or tend to be older than true depositional ages due to partial bleaching. As such, the previously considered late Pleistocene transgression may have occurred in the Holocene. Overall, the early Holocene transgression is well documented along Fujian coast revealing largely consistent early Holocene sea level histories from northern and southern sectors of Fujian coast. However, late Pleistocene transgressions are not well preserved along Fujian coasts, likely due to pervasive erosion. Our examination of the chronology of transgression in Fujian coast suggests cautions for 14C dating of bulk samples and for OSL dating of sediments in fluvial-deltaic settings, and emphasizes the importance of establishing a reliable chronological framework for understanding relative sea level history in this region and in similar settings elsewhere.

South China provides exceptional and unique sedimentary archives of Earth's fundamental changes in Ediacaran time. However, the lack of robust geochronological constraints renders a poorly-defined chronostratigraphic framework for Ediacaran-aged strata in South China, thus making it difficult to understand Earth's critical changes during this time interval. Magnetostratigraphy and rock magnetic cyclostratigraphy turn out to be a few reliable methods in chronostratigraphic studies, especially in the Precambrian. Here, we present a detailed paleomagnetic and rock magnetic study of the Ediacaran Doushantuo Formation in the Huanglianba section, Guizhou Province, South China. The section consists of ~75 m thick carbonate succession and has a record of one of the largest carbon isotope excursions in the Earth history, known as the Shuram excursion. Stepwise thermal demagnetization of Doushantuo carbonates reveals single-component magnetizations that yield a paleomagnetic pole consistent with the Late Triassic segment of the apparent polar wander path of South China. The secondary origin of Doushantuo carbonates' magnetization is supported by their magnetic mineralogy based on various rock magnetic experiments and scanning electron microscopic analyses. We interpret that the secondary magnetization resides mainly in authigenic pyrrhotite that likely precipitated from the reducing fluids during the late stage of Indosinian orogeny in the Triassic. Interestingly, the companion high-resolution cyclostratigraphic study of a 4-m thick succession at the upper layers of the Doushantuo Formation in the Huanglianba section indicates that the Milankovitch cycles were encoded in the variation of magnetic susceptibility, immune from the influence of remagnetization. Variation of magnetic susceptibility is attributed to changes in the abundance of paramagnetic minerals which, by implication, means that the amount of terrestrial materials transported from the continent was regulated by Milankovitch cycles during the deposition of Doushantuo carbonates. Therefore, our results suggest that even though carbonates are prone to remagnetization, astronomical modulation of deposition could be encoded in rock magnetics of the remagnetized carbonates. As a result, rock magnetic cyclostratigraphy has potential in remagnetized carbonates for providing a floating astronomical timescale that can be applied to constrain sediment accumulation rates, estimate the duration of geological events, and construct high-resolution chronostratigraphies.

Magnetic polymer/Fe3O4 nanocomposite particles (NCPs) have been widely used for many advanced applications. It is still a great challenge to efficiently synthesize polymer/Fe3O4 NCPs through a simple and convenient technique. In this work, carboxyl-functionalized polymer/Fe3O4 NCPs were efficiently and conveniently prepared through a one-pot miniemulsion polymerization by using methacrylic acid (MAA) as the functional comonomer and adopting a special use strategy of emulsifiers. The influence of synthesis parameters on the formation efficiency of polymer/Fe3O4 NCPs was quantitatively evaluated in terms of the number fraction of polymer/Fe3O4 NCPs (fNCP). The fNCP value in the as-synthesized emulsion reached above 80%. The interaction between MAA and Fe3O4 magnetic nanoparticles (MNPs) in the oil phase could promote the homogenous distribution of Fe3O4 MNPs among monomer droplets, while the interaction between the MAA monomeric units of copolymers and Fe3O4 MNPs could confine the Fe3O4 MNPs in the NCPs. Both interactions are beneficial to the formation of polymer/Fe3O4 NCPs. The controlled mergence between the monomer droplets and latex particles could also lead to the consumption of plain monomer droplets, and furthermore improve the formation of polymer/Fe3O4 NCPs.

Two low temperature cofirable ceramic materials with thermal expansion coefficients (TEC) of 5.9 ppm/K and 6.6 ppm/K, respectively, were used in this work to introduce residual stress by the multilayer cofiring process. Theoretical calculation and finite element method (FEM) simulation were used to optimize the multilayered ceramic substrate composition design to obtain enhanced mechanical performance. Based on the failure condition of materials, the multilayered ceramic substrate has an optimal thickness ratio of the surface layers to the whole laminate (sandwich structure). Indentation method was used to measure the surface residual stresses and 3-point bending tests were used to measure the mechanical strength. Enhanced mechanical strength of 404 MPa can be obtained when the thickness ratio of surface layer to the whole laminate is 0.19.

In this article, we deal with the existence of mild L-quasi-solutions for damped elastic systems in Banach spaces. The results improve and extend some relevant results in ordinary differential equations and partial differential equations. Under monotone condition and the noncompactness measure condition on nonlinearity, we obtain the existence of extremal mild solutions. In addition, two examples are given to illustrate our results.

In this article, we study the existence of mild solutions for damped elastic systems in Banach spaces. The discussion is based on the operator semigroup theory and fixed point theorem. In addition, two examples are given to illustrate our results.

An oceanic Greater Indian Basin was hypothesized to have formed between ∼120 Ma and ∼65 Ma by regional extension that separated the cratonic India from its northern margin of Tethyan Himalaya (TH). However, the lack of paleomagnetic data from this critical time interval in the TH marks an important gap in our knowledge about the tectonic evolution of the Greater India. We have conducted a paleomagnetic study of a Cretaceous marine succession in Zhongba, southern Tibet that consists of predominantly purple reddish cherts and siliceous limestone. Paleomagnetic samples from 12 sites were subjected to stepwise thermal demagnetization that revealed either two- or three-component magnetizations with the high-temperature component (HTC) typically unblocked at ∼650 °C. The HTCs exhibit dual polarities that yield a positive reversed test at 95% confidence level, suggesting a primary origin of the remanence. With chronologic constraints from the combined analysis of the magnetostratigraphic and radiolarian data, the HTCs yield a mean of Ds = 336.9°, Is = −50.7°, ks = 18.0, α95 = 5.3° for the ∼120.8–93.9 Ma interval of the TH, which corresponds to a paleopole at 25.0°N, 285.7°E (dp/dm = 4.8/7.1°). The apparent polar wander path (APWP) of the TH overall resembles that of cratonic India, suggesting no polarward separation that is sufficiently large to merit an oceanic basin between the TH and cratonic India. Therefore, our new reliable paleomagnetic data from the critical time interval do not support the Greater Indian Basin hypothesis and its implied dual collisional processes between India and Asia. On the other hand, the APWPs exhibit relative shifts for the post-120 Ma segment and the pre-130 Ma segment, indicating relative motions between the TH and cratonic India that most likely resulted from shearing along boundary-parallel faults during the India-Asia collision.

In this paper, we concern on the periodic boundary value problem for a class of semilinear impulsive fractional evolution equations in an ordered Banach space E. First, we establish the existence results of mild solutions for the associated linear periodic boundary value problem. Next, we obtain the existence results of mild solutions by using the monotone iterative technique with L-quasi-upper and lower solutions, the results are new and extend some previously known results. Finally, two examples are also given to illustrate the main results.

The late Mesozoic terrestrial strata in numerous basins in S (South) China provide important sedimentary archives to understand the tectonic evolution of S China and East Asia. However, establishing regional stratigraphic framework within a basin and precisely correlating strata among basins remain challenging due to limited chronological constraints. In this study, we report zircon U-Pb ages of 21 samples and a compilation of 132 reliable age data from 15 type sections of the volcanic-sedimentary basins in S China. The synthesized geochronology allows us to establish a refined chronostratigraphy for the late Mesozoic terrestrial strata. New calibrated results indicate that most of the lithostratigraphic units are diachronic, laterally stacking, and/or interfingering. Six stacking styles are classified for the relationship of lithostratigraphic units. Analysis of the refined chronostratigraphy and the stratal stacking styles, together with lithological composition, reveals three episodes of tectono-stratigraphic evolution. Episode I (~145–125 Ma) is characterized by intense volcanism, as evidenced by widespread occurrence of volcanic strata and (137–120 Ma) A-type granites, and was probably related to the rollback of the subducting Paleo-Pacific plate; The strata deposited during Episode II (~125–100 Ma) are composed of variegated sediments associated with/without volcanic intercalations in sedimentary faulted-depression basins, indicating the waning of volcanism and tectonism attributed to the ending of the Izanagi/Kula plate subduction; In Episode III (

The aim of this paper is to discuss the existence of mild solutions for a class of semilinear stochastic partial differential equation with nonlocal initial conditions and noncompact semigroups in a real separable Hilbert space. Combined with the theory of stochastic analysis and operator semigroups, a generalized Darbo’s fixed point theorem and a new estimation technique of the measure of noncompactness, we obtained the existence of mild solutions under the situation that the nonlinear term and nonlocal function satisfy some appropriate local growth conditions and a noncompactness measure condition. In addition, the condition of uniformly continuity of the nonlinearity is not required and also the strong restriction on the constants in the condition of noncompactness measure is completely deleted in this paper. An example to illustrate the feasibility of the main results is also given.

In this study, Er3+-doped and Er3+/Yb3+-co-doped xLiNbO3-(1-x)(K,Na)NbO3 (xLN-(1-x)KNN) ferroelectric ceramics were synthesized by a solid state reaction process and the samples were found to exhibit tunable upconversion luminescence (UCL) under an external electric field as well as excellent optical temperature-sensing properties. By altering the polarization time, UCL intensity was effectively controlled under an external electric field. Furthermore, an optimal UCL was observed in a 0.4LN-0.6KNN:Er3+,3Yb3+ sample and its excellent optical temperature sensitivity (0.006 K−1 at 643 K) from 83 to 663 K was 131% higher than that of 0.4LN-0.6KNN:Er3+. These results suggested that xLN-(1-x)KNN ferroelectric ceramics were promising candidates for an opto-electronic integrator and optical temperature sensors with high sensitivity and broad temperature range.

The excellent sensing capabilities of SnS2 and the electrical properties of reduced graphene oxide (rGO) are combined to achieve a low-operating temperature NO2 gas sensor. Conductometric gas sensors based on hybrid films of 2D SnS2-rGO are fabricated and evaluated for humidity and different target gases including NO2, CH4, NH3, C2H5OH (ethanol), (CH3)2CO (acetone) at different operating temperatures ranging from 25 °C to 100 °C. The sensor shows exclusive selectivity and reversibility to NO2 as compared to the other analytes, with a low detection limit of 0.6 ppm and a response of 9.8% at 80 °C. The sensing mechanism of the hybrid SnS2-rGO system is described by analysing the effect of NO2 gas on the depletion region established at the interface between SnS2 and rGO layers.