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Micro air vehicles with propellers have been widely used in military and civilian applications due to their high maneuverability and low cost. As the mission scenarios and requirements of rotorcrafts become more complex, proximity effects caused by confined environments, such as the ceiling effect cause significant interference to the performance and stability of rotors. Most researchers have analyzed this phenomenon by considering the ceiling effect in hover conditions. However, few scholars considered the tilt angle between the rotor and the ceiling, which is more likely to occur in real missions, such as the close inspection of bridges or large equipment, flight in narrow indoor environments, and flight near the ceiling for fully actuated multirotors. In this study, a CFD-based study is conducted to evaluate the ceiling effect for small-scale tilted propellers. The aerodynamic analysis was experimentally evaluated through a series of ground tests in a test bench designed for this research. The CFD results were validated by a mesh-independent study and experimental data comparison. The results show that in contrast to the phenomenon of reduced thrust when tilt angles exist between the rotors and ground, the existence of tilt angles between the propeller and the ceiling reduces the thrust-increasing effect of the ceiling when the dimensionless distance is greater than 0.6. When the distance gets smaller, the thrust-increasing effect increases when the tilt angle is greater than 10 ∘. In particular, when the distance is less than 0.3, the existence of tilt angles will increase the thrust-increasing effect of the ceiling. Additionally, a data-driven model has been proposed to predict the thrust with the distance to the ceiling and the angle inclination between the rotor and the ceiling. This model enables future rotorcrafts that require accurate models to operate in narrow environments. [ABSTRACT FROM AUTHOR]

Metallic glass (MG) shows great potential for a wide range of functional and structural applications. However, it remains a challenge to enhance the ductility of metallic glasses without compromising their strength during development. A composite of bulk metallic glass/graphene (BMG/C (n)) was prepared using the suction casting method in argon atmosphere, with a nominal composition of (Zr 60 Ni 20 Al 20) 100-x (C (n)) x (x = 5,10,15). The results indicate that the graphene well dispersed in the BMG matrix without any other intermetallic compounds present. Mechanical property testing reveals a significant increase in both plasticity and hardness with increasing graphene content, while maintaining high fracture strength of the BMG matrix. [Display omitted] • An effective method for preparing BMG-graphene composite was presented. • A dual-phase structure of the BMG and graphene were designed. • The strength-plasticity synergy in this composite was presented. • The plasticity of this composite has been increased by about 6 times. [ABSTRACT FROM AUTHOR]

A series of disaster risk reduction (DRR) programs were carried out in landslide-prone areas in the Three Gorges Reservoir (TGR) to improve community resilience. The Wanzhou District in the TGR was selected as a case to introduce the community-based DRR (CBDRR) system. The system is community-based and government-led with the assistance of experts, police, Red Cross, etc. It involves risk investigation, education and training, landslide monitoring, information analysis, early warning system and emergency response. The landslide mechanism and element at risk were ascertained after detailed field investigation. Based on investigation, a characterized education and training to local residents was carried out. The local residents living on landslides carried out the community-based landslide monitoring. Some simple but effective monitoring methods were applied, such as steel piles, mosaic, convergence meters and smart phone, which are widely used in community-based landslide monitoring. To comprehensively understand the landslide and the data monitored by local residents, a real-time landslide monitoring system was established on several typical landslides. At last, a successful landslide emergency response was introduced to well explain the early warning system and emergency response. After carrying out the CBDRR for a decade, the landslide resilience has enhanced and the local residents are more relieved to live on landslides. [ABSTRACT FROM AUTHOR]

The density functional theory (DFT) is used to investigate the geometries, relative stabilities, electronic properties and natural population analysis for small neutral, anionic, and cationic indium clusters. From 2D to 3D structures of the neutral, anionic, and cationic indium clusters are studied. The optimized results indicate that the geometries of the anionic and cationic indium clusters exhibit large similarities from those of neutral indium. According to the calculations of the averaged binding energy, fragmentation energy, and second-order energy difference, we estimate the relative stabilities of In n (0,±1) clusters. Odd–even alterations are found in the adiabatic electron affinity (AEA), vertical electron detachment energy (VDE), adiabatic ionization potential energy (AIP), and vertical ionization potential energy (VIP) for the neutral, anionic, and cationic indium clusters. In 14 has the highest AEA, In 10 has the highest VDE, In 13 has the highest AIP, and In 5 has the highest VIP. The HOMO–LUMO gaps are also calculated for the In n (0,±1) clusters to investigate their electronic properties. Natural population analysis reveals that the sign of the charge are zero for In n clusters, In n − clusters occupy the negative charges and In n + clusters occupy the positive charges. [ABSTRACT FROM AUTHOR]

• Sources and general situation of incineration industrial by-products were summarized. • Physicochemical properties of incineration industrial by-products were discussed. • The effects and hydration mechanism of incinerated ash CLSMs were analyzed. • Incineration ash can be used to prepare cementless CLSM. Incineration industrial by-products can be used as supplementary cementitious materials (SCMs) to degrade the cement output, thereby reducing fossil-fuel combustion and contributing to the utilization and management of waste resources. This paper summarizes the state-of-the-art uses of incineration industrial by-products (coal ash, waste incineration ash, and biomass incineration ash), which are used as SCMs in partial cement replacement. It also summarizes alkali-activated by-products as cementitious materials that replace all cement with controlled low-strength material (CLSM). After introducing the general situation and physicochemical characteristics of these pozzolanic incineration ashes, the influences and mechanisms of the by-products on the performance of CLSM are summarized and analyzed. The discussions and analyses in this paper are expected to inspire further research and provide a basis for the sustainable development of CLSMs from incineration industrial by-products as cementitious materials. [ABSTRACT FROM AUTHOR]

We report a computational study of the aluminum doped germanium clusters Ge n Al ( n = 1–9). The molecular geometries and electronic structures of the Ge n Al clusters are investigated systematically using quantum calculations at the B3LYP level with the 6-311G(d) basis sets. The growth pattern behaviors, stabilities, electronic properties, and magnetic moments of these clusters are discussed in detail. Obviously different growth patterns appear between small and larger Al-doped germanium clusters, the optimized equilibrium geometries trend to prefer the close-packed configurations for Al-doped germanium clusters up to n = 9. The size dependence of cluster average binding energies per atom ( E b /atom), second-order differences of total energies ( Δ 2 E ), fragmentation energies ( E f ) and HOMO–LUMO gaps of Ge n +1 and Ge n Al ( n = 1–9) clusters are studied. The stability results show that Ge n +1 cluster possess relatively higher stability than Ge n Al cluster. Furthermore, the investigated highest occupied molecular orbital-lowest unoccupied molecular orbital gaps indicate that the Ge n +1 and Ge n Al clusters have different HOMO–LUMO gap. In addition, the calculated vertical ionization potentials and vertical electron affinities confirm the electric properties of Ge n +1 and Ge n Al clusters. Besides, the doping of Al atom also brings the decrease as the cluster sizes increase for atomic magnetic moments ( μ b ). [ABSTRACT FROM AUTHOR]

The Geometries, relative stabilities, and electronic properties of the most stable host Ga n +1 and doped Ga n Ti (0, ±1) ( n = 1–10) clusters are studied using density functional theory (DFT) with valence basis set LANL2DZ. We determine the equilibrium geometries of host Ga n +1 and doped Ga n Ti( 0, ±1) ( n = 1–10) clusters by optimizing the bond length and bond angle of various structural isomers. With increasing cluster size, the Ga n Ti (0, ±1) clusters tend to adopt compact structures, and the ground state structures of Ga n Ti ±1 keep the similar geometric structure as the Ga n Ti clusters. When the number of Ga atom is even, the natural population analysis of Ga n Ti − clusters possess high charges transfer. In order to study the stability of cluster, the average binding energies per atom ( E b /atom), fragmentation energies ( E f ), second-order differences of total energies (Δ 2 E ) of host Ga n +1 and doped Ga n Ti (0, ±1) ( n = 1–10) clusters are studied. The calculation results of fragmentation energies of Ga n +1 clusters present a leaping odd–even oscillatory behavior from n = 1 to n = 10. Furthermore, the calculated HOMO–LUMO gaps of Ga n Ti clusters are distinctly higher than those of Ga n +1 clusters, except for Ga 3 Ti clusters. The size dependence of cluster’s vertical electron detachment energies (VDE), adiabatic electron affinities (AEA), and adiabatic ionization potentials (AIP), vertical ionization potentials (VIP) are discussed. [ABSTRACT FROM AUTHOR]

Abstract: This paper is concerned with the global asymptotic stability of a stochastic delay predator–prey system with Beddington–DeAngelis functional response. Sufficient criteria for the global asymptotic stability of the system are established. Some simulation figures are provided to show that our model is more realistic than existing models. [Copyright &y& Elsevier]

Abstract: This paper is related to a class of inverse problems for identification of the coefficient in a square porous medium. The unknown coefficient depends on the solution and belongs the class of admissible coefficients. Using continuous dependence of solutions on the coefficient convergence in the corresponding direct problems, the existence of the quasi-solution of the inverse problem is obtained in the appropriate class of admissible coefficients. [Copyright &y& Elsevier]

Abstract: The structure, stability and electronic properties of the different B-site partial substituted derivatives LaNi4.5M0.5 (M=Al, Mn, Fe, Co) have been investigated by means of the density functional theory using the full-potential linearized augmented plane wave (FLAPW) method with the generalized gradient approximation (GGA). The optimized results indicate that all of Al, Mn, Fe, Co atoms prefer to substitute Ni atoms in the 3g sites. Due to the different radius of elements, the cell volume would increase with the doping Ni (3g) atoms. And the sequence of volume is LaNi4.5Al0.5 >LaNi4.5Mn0.5 >LaNi4.5Fe0.5 >LaNi4.5Co0.5 >LaNi5, which is in agreement with the experimental result. The calculated data of formation and cohesive energies indicate that LaNi4.5Mn0.5 has the stablest structure among five alloys. Based on the analysis of the density of states and charge density, the interactions of Mn–Ni, Fe–Ni, Co–Ni atoms are greatly stronger compared to the Ni–Ni interaction, while the interaction of Al–Ni atoms is weakened. Based on the formation energy of hydrogen atom in LaNi4.5M0.5H0.5, the sequence of bounding hydrogen atoms is LaNi4.5Mn0.5 >LaNi4.5Fe0.5 >LaNi4.5Co0.5 >LaNi4.5Al0.5 >LaNi5. [Copyright &y& Elsevier]

Abstract: In this paper, we prove the existence and uniqueness of solutions for systems of fractional differential equations with antiperiodic boundary conditions by applying some standard fixed point principles. [Copyright &y& Elsevier]

Abstract: In this paper, we consider the existence of solutions for first order nonlinear impulsive functional integro-differential equations with integral boundary value conditions. We firstly build a new comparison theorem. Then by utilizing the monotone iterative technique and the method of lower and upper solutions, we obtain the existence of extremal solutions or quasi-solutions. [Copyright &y& Elsevier]

Abstract: In this paper, we study the impulsive integro-differential equationsThe existence of maximal and minimal solutions to the problem is proved by using an upper and lower solutions method together with monotone iterative technique. And two monotone sequences which uniformly converge to the relevant solutions are obtained. An example is included to show the applicability of our results. [Copyright &y& Elsevier]

A mammary-derived growth inhibitor-related gene (MRG) was previously identified and characterized. MRG induces differentiation of mammary epithelial cells in vitro and its expression is associated with mammary differentiation. To further define the role of MRG on mammary gland differentiation, a MRG transgenic mice model under the control of mouse mammary tumor virus promoter was established and the effect of MRG on mammary gland differentiation was investigated at histological and molecular levels. Expression of endogenous mouse MRG gene was significantly increased from the non-differentiated gland of control virgin mice to the functionally differentiated gland of pregnant control mice. Whole mount analyses demonstrated that ductal development was not affected by MRG transgene expression. While there was no lobuloalveolar structure in control virgin mice, expression of MRG transgene in the mammary gland resulted in the development of lobuloalveolar-like structure, which mimics the gland from early pregnancy. Consistent with the morphological change, expression of MRG also increased milk protein β-casein expression in the gland. To study the mechanism of MRG-induced mammary differentiation, we investigated the Stat5 activation in the glands from the transgenic mouse versus virgin control mouse. While activated Stat5 was expressed at the minimal level in the non-differentiated control virgin gland, a significant Stat5 phosphorylation was observed in the virgin transgenic gland. Our data indicate that MRG is a mediator of the differentiating effects of pregnancy on breast epithelium, and overexpression of MRG in young nulliparous mice can induce differentiation. [ABSTRACT FROM AUTHOR]

Herein, La 0.7 Ca 0.3− x K x MnO 3 (LCKMO) films with highly oriented growth were prepared on La 0.3 Sr 0.7 Al 0.65 Ta 0.35 O 3 (00 l) substrates by sol–gel spin coating method. Comprehensive analysis of microstructure, surface morphology, ion valence, and electrical transport properties of LCKMO films indicates that the substitution of K+ ions for Ca2+ ions increased the ratio of Mn4+/(Mn3+ + Mn4+), narrowed the one electron bandwidth, and enhanced double exchange mechanism and electron–lattice coupling. Moreover, the doping of K+ ions induced the dense and uniform conical-structured growth of grains on the surface of the films. Results demonstrated that at x = 0.1, LCKMO film exhibited the maximum TCR of 17.84% K−1 at 253.07 K, which was 31.76% higher than that of previously reported La 1− x−y Ca x K y MnO 3 ceramic with the highest TCR. Further theoretical insights into the effects of Ca/K co-doping on electrical transport properties were supplemented. [ABSTRACT FROM AUTHOR]

A butanol-based fast condensation particle counter (Fast CPC, Model 3650, Kanomax Inc., Japan) was characterized in this study with three different types of monodisperse particles, including positively and negatively charged nickel-chromium (Ni/Cr) particles, positively charged tetraheptyl ammonium bromide (THABr) and tetrabutyl ammonium bromide (TBABr) particles, and positively charged polyethylene glycol (PEG) particles. The PEG particles were characterized with varied numbers of charges, whereby the charge number effect on particle activation was investigated. The performance of the Fast CPC was compared with a TSI® 3775 CPC and a TSI® 3776 CPC, respectively, under both factory temperature settings and boosted temperature settings, the latter of which corresponded to the brink of butanol homogeneous nucleation. Our results show that size-resolved Ni/Cr particles were detected by the Fast CPC with comparable detection efficiencies regardless of the charge polarity. When the charge number on a PEG particle increased from 1 to 3, an increasing tendency of the detection efficiency was observed, hinting that multiple charges on a particle will facilitate its activation. Particle activation was affected by the particle chemical composition as well, which is suggested by the higher activation efficiencies of PEG particles than those of Ni/Cr particles. The effects of multiple charges and chemical composition on particle activation were both more significant under factory temperature settings, but became less pronounced under boosted temperature settings. In addition to a quicker response time, the Fast CPC was capable of detecting sub-3 nm particles under boosted temperature settings, with the detection efficiency higher than that of the 3775 CPC but lower than that of the 3776 CPC, and can be used as a good candidate for the measurement of rapidly varying concentrations of small particles. • Fast CPC can detect small particles of rapidly varying concentrations. • Boosted CPC temperature settings is recommended for sub-3 nm particle measurements. • Effects of multiple charges on particle activation are investigated. • Effects of chemical composition on particle activation are investigated. [ABSTRACT FROM AUTHOR]

Scanning mobility particle sizer (SMPS) is widely used for particle number size distribution measurements of submicron particles. In this work, two TSI® SMPSs equipped with a soft X-ray neutralizer and a Kr-85 neutralizer, respectively, were operated in parallel to measure particle number size distributions of ambient air. An independent TSI® ultrafine condensation particle counter (CPC) was used as a reference to measure the total concentration of particles in the ambient air. Our results show that the total particle concentrations measured by the two SMPSs were comparable with each other, while their size-resolved concentration ratios were size-dependent and relative humidity (RH)-dependent. Neutralizer was found to be essential to quickly bring small particles to charge equilibrium in field measurements, as indicated by the comparison of particle number size distributions measured by the Kr-85 SMPS with those inverted from naturally charged particles. The total particle concentrations measured by two SMPSs tend to exceed those by the reference CPC at high RH, hinting that the particle concentrations measured by SMPSs could be overestimated at high RH. This study urges a better understanding of the bipolar charging processes under high RH conditions. • Size-resolved concentration ratios by X-ray &85Kr SMPSs are size- & RH-dependent. • Neutralizers are essential to quickly bring small particles to charge equilibrium. • Particle concentrations observed by X-ray &85Kr SMPSs are overestimated at high RH. • A better understanding of bipolar charging processes under high RH is needed. [ABSTRACT FROM AUTHOR]

Two-Dimensional carbon-based materials as a potential hydrogen storage medium have attracted great attention. In this study, various key aspects such as structure, electronic properties, stability, and hydrogen storage performance of Na-modified Irida-Graphene (IG) were thoroughly investigated using density functional theory (DFT) calculation methods. The calculation results show that the binding energy of Na atoms with the substrate is 1.51 eV, far exceeding the cohesive energy. The AIMD results reflect the good thermal stability of the model. One Na atom can adsorb up to 5H 2 molecules. The IG loaded with eight Na atoms on both sides can adsorb 32H 2 molecules, achieving a hydrogen storage capacity of 7.82 wt % , far exceeding the US DOE target of 5.5 wt %. The calculated Van 't Hoff equation indicates a desorption temperature of 248 K for the model. Moreover, reversible hydrogen storage can be achieved at medium to low pressures, with desorption temperatures ranging from 285 K to 417 K. These results suggest that Na-Modified IG models are candidate materials for reversible hydrogen storage under near-ambient conditions. [Display omitted] • Sodium modification of Irida-Graphene enhances its hydrogen adsorption capacity. • The interaction between IG-Na and H 2 was analyzed using the IGMH method. • The hydrogen storage capacity of IG-Na medium reaches 7.82%. [ABSTRACT FROM AUTHOR]

Electrical mobility and mass of atmospheric ions are of great importance, since both properties jointly determine their charging states. In this work, different carrier gases of bottle N 2 , bottle air, and particle-free lab air were passed through a TSI® soft X-ray aerosol neutralizer to produce both positive and negative ions. The electrical mobilities and mass-to-charge ratios of these ions were measured with a high-resolution half-mini differential mobility analyzer (DMA) coupled to an atmospheric pressure interface time-of-flight (APi-TOF) mass spectrometer. The effects of carrier gas, sample flowrate, and relative humidity (RH) on the ion mobility and mass-to-charge ratio were evaluated. Most detected ions could be traced back to the impurities in the carrier gases, or the compounds used to manufacture the system components. However, severe fragmentation of DMA-classified clusters was observed, especially under high RH conditions, which likely occurred inside the APi-TOF and complicated the identification of the chemical composition of the DMA-classified clusters. The mobility spectra and ion identities were comparable when using bottle N 2 and bottle air as the carrier gas, whereas different features on ion mobility and mass-to-charge ratio were found in the case of particle-free lab air. Residence time of the carrier gas inside the neutralizer as a function of the sample flowrate, when at the order of a few seconds, exerted a weak impact on the ion mobility spectra. The effect of RH on the electrical mobility was contingent on the polarity and chemical composition of ions. The presence of water vapor would grow the acid radical ions and hydronium ions to larger sizes by forming clusters, whereas the positively charged polydimethylsiloxanes in the case of particle-free lab air were marginally impacted. In addition, the concentration of neutral clusters formed through the ion-ion recombination or radiolysis was measured with a particle size magnifier (PSM). Compared with those in the case of bottle gases, the neutral cluster concentrations were significantly larger when particle-free lab air was used as the carrier gas. Higher concentrations of neutral clusters were observed in the high RH experiments, likely because high RH could either enhance the ion-ion recombination or the detection efficiency of PSM. Our work indicates that RH and the impurities in the carrier gas have a significant effect on the measured electrical mobilities and mass spectra for ions generated by a soft X-ray aerosol neutralizer. • Properties of bipolar ions produced in a soft X-ray neutralizer were measured. • Ion species generated from different carrier gases were compared. • Residence time exerted a weak impact on the ion mobility spectra. • Relative humidity induced-shift in ion mobility was contingent on ion properties. • High concentrations of sub-2 nm neutral clusters were formed and observed. [ABSTRACT FROM AUTHOR]

Organic acids are important contributors to the acidity of atmospheric precipitation, but their existence in the Chinese atmosphere is largely unclear. In this study, twelve atmospheric gaseous organic acids, including C 1 -C 9 alkanoic acids, methacrylic acid, pyruvic acid, and benzoic acid, were observed in the suburb of Wangdu, Hebei Province, a typical rural site in the northern China plain from 16th December, 2018 to 22nd January, 2019, using a Vocus® Proton-Transfer-Reaction time-of-flight mass spectrometer (Vocus PTR-ToF). The quantification of C 2 -C 4 alkanoic acids by the Vocus PTR-ToF was calibrated according to the titration of a NaOH solution by C 2 -C 4 alkanoic acids from home-made permeation sources, and the other organic acids except for formic acid were quantified based on the k cap -sensitivity linearity in the Vocus PTR-ToF, whereas formic acid was not quantified because our instrument setting led to a significant underestimation in its concentration. The average total concentration of eleven gaseous organic acids was 6.96 ± 5.20 ppbv (parts per billion by volume). The average concentration of acetic acid was the highest (3.86 ± 3.00 ppbv), followed by propanoic acid, butyric acid, and methacrylic acid. Domestic straw burning was likely the dominant source of the observed gaseous organic acids according to the good correlations between acetonitrile and organic acids and between particulate K+ and organic acids, and traffic emissions could also have contributed. During episodes with continuously high concentrations of organic acids, short-distance transport dominated in Wangdu according to the backward trajectory analysis. Baoding, Shijiazhuang, and Hengshui areas were the main source areas based on potential source contribution function and concentration weighing track analysis. [Display omitted] [ABSTRACT FROM AUTHOR]

Various transition metals were employed to enhance the catalytic performance and N 2 selectivity of Mn-based catalysts. The modification of Fe and Cu promoted the low-temperature activity, while the Al-modified catalyst displayed the highest N 2 selectivity close to 100 %. The characterization results proved that the content of O β and Mn4+ were increased after adding transition metals. N 2 selectivity experiments revealed that the reduction of NO to N 2 O and the oxidation of NH 3 to N 2 O did not occur. The product of NH 3 oxidation was only N 2. Combined with the results of the in-situ DRIFTS experiments, it was proposed that N 2 O was generated from the decomposition of NHNO and NH 4 NO 3 in the SCR reaction. The poor N 2 selectivity of the unmodified catalyst was related to the existence of inactive N 2 O 2 2- species on the surface, while the high content of active NH 2 - species on the Mn 0.1 Ho 0.005 Ce 0.015 Al 0.01 /TiO 2 catalyst enhanced its catalytic activity and N 2 selectivity. In addition, the results also revealed that only the E-R mechanism existed on the unmodified catalyst, while both the E-R and L-H mechanism were activated after the transition metal modification. The SCR reaction of NH 3 and NO proved to be the source of N 2 O. The activation of the L-H mechanism might play a key role in the improvement of activity and selectivity. [Display omitted] [ABSTRACT FROM AUTHOR]

Abstract: The micro-arrangement of hydrogen atoms and the electronic properties of LaNi4.5Fe0.5H0.5 have been systematically investigated using the full-potential linearized augmented plane wave (FP-LAPW) method within the generalized gradient approximation (GGA) scheme. Firstly, the sizes of fourteen interstitial sites have been recalculated according to the Gross's method, and it is found that the radius of every interstitial site slightly increases with the substitution of Fe atom. By modeling and optimizing, the calculated results indicate that H atom prefers to occupy the 6m⁎ site (“⁎” denotes the sites in the Fe-substituted unit cell.) in the solid solution phase. In addition, the cohesive energy of LaNi4.5Fe0.5 is 5.87eV, while that of LaNi4.5Fe0.5H0.5 is 5.99eV, which indicates that the hydrides LaNi4.5Fe0.5H0.5 become more stable in contrasting with the host alloy. Based on the analysis of electric structures, the strong interaction between Fe atom and H atom improves the good characteristics of storing hydrogen for LaNi4.5Fe0.5 alloy. [Copyright &y& Elsevier]

The morphology of carbon nanomaterials plays significant effect on the complex permittivity and microwave absorption (MA) capability. Elaborate morphology design would bring about efficient MA performance. In this work, we develop a hollow mesoporous carbon microspheres with different shells (from single to quadruple shells) through a facile template method and layer-by-layer etching process. This multi-shell hollow mesoporous carbon microspheres (MS-HMCMs) can be regarded as a complex composite morphology consisting of hollow, mesoporous and yolk-shell structure, which presents the tunable number of shells for optimal impedance matching, multiple interfacial polarization and the extended microwave transmission path from internal spaces. Thus, the MS-HMCMs demonstrates wide effective absorption bandwidth (EAB) of 6.4 GHz and 5.96 GHz at the thicknesses of 2.5 mm and 3.0 mm. Besides, the complex permittivity and MA properties can be effectively tuned via regulating the shell numbers. This MS-HMCMs with controllable shells may be a promising wideband and lightweight microwave absorber. [ABSTRACT FROM AUTHOR]

The use of natural starch as a replacement for petroleum-based packaging materials is limited due to its poor processability, weak mechanical properties, and strong moisture sensitivity. To address these limitations, this study adopts molecular design of hydroxypropylation and acetylation to sequentially modify natural starch, and material design of introducing acetylated cellulose nanofibers (ACNF) into the starch matrix to reinforce the material. Hydroxypropylation decreased the interaction force between the starch molecular chains, thereby reducing the glass transition temperature. Subsequent acetylation introduced hydrophobic acetyl groups that disrupted intermolecular hydrogen bonds, enhancing the mobility of the starch molecular chain, and endowed the hydroxypropyl starch acetate (HPSA) with excellent thermoplastic processability (melt index of 7.12 g/10 min) without the need for plasticizers and notable water resistance (water absorption rate of 3.0 %). The introduction of ACNF generated a strong interaction between HPSA chains, promoting the derived ACNF-HPSA to exhibit excellent mechanical strength, such as high impact strength of 2.1 kJ/m2, tensile strength of 22.89 MPa, elasticity modulus of 813.22 MPa, flexural strength of 24.18 MPa and flexural modulus of 1367.88 MPa. Its overall performance even surpassed that of polypropylene (PP) plastic, making it a potential alternative material for PP-based packaging materials. [Display omitted] [ABSTRACT FROM AUTHOR]

Abstract: This paper discusses a general stochastic Lotka–Volterra system with delays. Some conditions for the global asymptotic stability are established. [Copyright &y& Elsevier]

Abstract: Topographic information is of fundamental importance for various scientific investigations in lunar and planetary exploration. To provide high-precision, seamless mapping capability, it is critical to co-register image and altimetry data, the two major data sources for topographic modeling. This paper presents a method for co-registration of Chang’E-1 (CE-1) stereo images and laser altimeter (LAM) data with crossover adjustment and refinement of the image sensor model. The crossover adjustment is tested in a larger area (0–60°N, 50–0°W); the image refinement and co-registration with LAM data are tested in an area (46.2–50.0°N, 31.8–28.8°W) within the larger area. Experimental results demonstrate that this co-registration reduces the mean differences of inconsistency from more than 200m to just 3.21m in the Z direction of object space. In image space, the mean errors of homologous points both in the column and row directions are reduced to below 0.1 pixel. This indicates that the proposed crossover adjustment of LAM data and refinement of the CE-1 stereo image model can effectively improve co-registration of the two data sets. [Copyright &y& Elsevier]

Abstract: In this paper, we deal with an inverse source problem of integro-differential parabolic equations, which comes from nonlinear pollution problems in porous media. We study the existence and uniqueness of solutions for the direct problem as well as the existence of quasisolutions of the inverse source problem in an appropriate class of admissible source functions. [Copyright &y& Elsevier]

Cork materials have the property of elastic deformation under pressure due to their unique closed, porous, cell structure with thin cell wall; and they accordingly need a surface coating that matches their deformation during there being used as floor materials. However, traditional wood coatings are hard, brittle, and mostly suitable for stiff wood surfaces, which are difficult to be directly adapted to the requirements of flexible cork. Although waterborne polyurethane (WPU) has the advantage of property tailorability, its fully applicable to cork materials are still a challenge. Herein, this study utilized a simple physical blending of waterborne polyurethane and nanocellulose with high aspect ratio, to develop a high-strength coating that matches the elastic deformation requirements of cork materials. When both two kinds of nanocellulose, poplar wood nanocellulose (WCNF) with an aspect ratio of 800 and bacterial nanocellulose (BCNF) with an aspect ratio of 2000, was individually added into the WPU emulsion at 0.5 wt%, the tensile strength and elastic modulus of the nanocellulose-modified polyurethane coating increased by 48.58 % and 118.88 %, 54.50 % and 120.48 %, respectively, compared to those of the pure WPU coating (14.09 MPa and 312.74 MPa). It is notable that both the nanocellulose-modified coatings showed no signs of damage on the cork surface even they underwent continuous bending over 2000 cycles, which indicates their excellent flexural fatigue resistance. Interestingly, such nanocellulose-modified coatings maintain comparable transparency, gloss, adhesion, solvent resistance and even present slightly improved hardness and wear resistance than their pure WPU coatings. Overall, the two nanocelluloses are comparative to the modification of the coatings, both of which could match the elastic deformation requirements of cork materials. Therefore, the nanocellulose physically blended polyurethane technology provides a simple and effective solution for the design and property tailoring of flexible coatings for cork floor. [Display omitted] • The two kinds of nanocellulose well and physically dispersed in the WPU coating. • The two nanocelluloses well maintained the coating transparency even at 0.5 wt%. • The nanocelluloses endow the coating with both excellent stiffness and flexibility. • The coating shows excellent flexural fatigue resistance over 2000 cycles bending. • The coating could meet the requirement of elastic deformation of cork floor. [ABSTRACT FROM AUTHOR]

Keep composting matrix in continuous collision and friction under a relatively high-temperature can significantly accelerate the progress of composting. A bioreactor was designed according to the novel process. Using this technology, organic fertilizer could be produced within 96 h. The electric conductivity (EC) and pH value reached to a stable value of 2.35 mS/cm and 7.7 after 96 h of fermentation. The total carbon/total nitrogen (TC/TN) and dissolved carbon/dissolved nitrogen (DC/DN) ratio was decrease from 27.3 and 36.2 to 17.4 and 7.6 respectively. In contrast, it needed 24 days to achieve the similar result in traditional static composting (TSC). Compost particles with different size were analyzed to explore the rapid degradation mechanism of food waste. The evidence of anaerobic fermentation was firstly discovered in aerobic composting. [ABSTRACT FROM AUTHOR]

In our study, solid alkali were produced and characterized by a series of methods. Dissolution of corn stalk was achieved in solvent systems at 170 °C for 5 h by cooking with solid alkali. The components of ionic liquid and water in solvent systems showed synergistic effects on lignocellulosic dissolution and degradation. Alkaline molecular sieves were proven to be the most effective solid alkali for lignin degradation, which promoted the dissolution efficiency of the corn stalk in solvent systems. Under the combined action of solid alkali and the nucleophilic component in solvent systems, lignin and hemicellulose in corn stalk were degraded. It effectively enhanced cellulose solubilization in solvent systems. The regenerated cellulose was demonstrated to be similar to microcrystalline cellulose according to Fourier Transform infrared spectroscopy and Nuclear Magnetic Resonance analyses. X-ray diffraction curves showed that the crystallinity of the regenerated cellulose is lower than that of microcrystalline cellulose. [ABSTRACT FROM AUTHOR]

Craters are distinctive features on the surfaces of most terrestrial planets. Craters reveal the relative ages of surface units and provide information on surface geology. Extracting craters is one of the fundamental tasks in planetary research. Although many automated crater detection algorithms have been developed to exact craters from image or topographic data, most of them are applicable only in particular regions, and only a few can be widely used, especially in complex surface settings. In this study, we present a machine learning approach to crater detection from topographic data. This approach includes two steps: detecting square regions which contain one crater with the use of a boosting algorithm and delineating the rims of the crater in each square region by local terrain analysis and circular Hough transform. A new variant of Haar-like features (scaled Haar-like features) is proposed and combined with traditional Haar-like features and local binary pattern features to enhance the performance of the classifier. Experimental results with the use of Mars topographic data demonstrate that the developed approach can significantly decrease the false positive detection rate while maintaining a relatively high true positive detection rate even in challenging sites. [ABSTRACT FROM AUTHOR]