Abstract:In this paper, we study some basic properties of k-quasi-homogeneous Toeplitz operators on the pluriharmonic Bergman space of the unit ball, and obtain the symmetric properties of the commutator and semi-commutator consisting of two such operators. In addition, we obtain the sufficient and necessary conditions for the finite rank of commutator and semi-commutator of two monomial-type Toeplitz operators.

Abstract:This paper aims at numerical solution of the partial differential equations (PDEs) with stochastic parameters. We propose a Gaussian-process-based emulator which is capable of choosing the training data adaptively. This model begins with limited training data, trains the Gaussian process emulator, adds the parameters with the highest prediction variance indicator from the parameter pool, along with the corresponding high-fidelity PDE output, into the training data set, until the model achieves a desired accuracy. A 2D parametric diffusion equation is used to test the model. Numerical results demonstrate the efficiency of the model. The accuracy of the model increases rapidly with the growth of training data. Only 40 training data allow us to obtain the desired accuracy.

Abstract:In this paper, we study existence of positive solutions for a class of nonlinear fourth-order ordinary differential equation with boundary values. The proofs of the main results are based on the fixed-point theorem of cone expansion-compression.

Abstract:In this paper, numerical solution of the initial-boundary value problem for the dissipative generalized SRLW equation with damping term is considered. A three-level linearized difference scheme with second order accuracy is proposed. It is proved that the difference scheme is convergent and stable by using the mathematical induction and the discrete function analysis. Efficiency of the method is demonstrated by some numerical examples.

Abstract:In this paper, the existence and multiplicity of positive solutions of a class of nonlinear second-order boundary value problem. The proofs of the main results are based on the fixed point theory on cone.

Abstract:In this paper, we study the existence of positive solutions for a class of singular second-order ordinary differential equations with nonlinear boundary conditions. The proof of main result is based on Krasnoselskii fixed point theorem.

Abstract:In this paper, we consider the existence of positive solutions of a nonlinear second-order periodic problem. The proofs of the main results are based on the fixed point index theory in cones.

Abstract:Aiming at the facts that user and project description information is not fully utilized in personalized recommendation and user score matrix data set is extremely sparse, a hybrid recommendation algorithm based on deep neural network and probabilistic matrix factorization (PMF) is proposed. Firstly, user and item description information is preprocessed to form user and item feature sets containing user preference, and then each feature is fed into the deep neural network model for training. At the same time, the probabilistic matrix decomposition model is used to optimize the potential eigenvectors based on the maximum posterior estimation of the user score matrix. Then the potential feature vectors of the probabilistic matrix model and the real feature vectors of the deep neural network model are iteratively updated to converge to the potential feature vectors that fuse the real information of the user and the item. Finally, this feature vector is used to make personalized recommendation to users. Experiments show that the proposed algorithm is better than the classical recommendation algorithm and previous algorithms in term of the mean square error and mean absolute error index, which shows the effectiveness of the proposed algorithm.

Abstract:String matching method and coarsegrained sentiment analysis method are often used in sensitive information detection，the accuracy, however, is rather low. To mitigate this issue, this paper proposed a method based on phraselevel sentiment analysis. This method takes advantage of a rule set which is used to extract phrases concerning the sensitive word, by analyzing the sentiment orientation of relative phrases, it is possible to determine the sentiment orientation of the expresser towards the sensitive word, thus determine the sensitivity of the information. This method takes the context of the sensitive word into consideration and is able to extract sentiment orientation towards the sensitive word instead of the whole text, which is missing from string matching method and coarsegrained method respectively. Experimental results suggest that the accuracy is considerably increased compared to string matching and coarsegrained sentiment analysis method.

Abstract:Spectral clustering algorithm is one of the classical community detection algorithms. Due to the current constructed similarity graphs carry less community structure information, the actual clustering effect has a big gap with the ideal clustering effect. Therefore, based on degree corrected stochastic block model and Markov chain, a novel spectral clustering approach for community detection, called MSCD, is proposed. Firstly, probability matrix composed of the connection probability between nodes is introduced based on DCBM, and the mapping relationship is established between probability matrix and similar matrix. Then, Markov chain is utilized to reconstruct the similar graph of spectral clustering. Finally, the reconstructed similar graph is used to partition the networks into clusters. Three typical algorithms of SC, MRWKNN and FluidC are performed on synthetic networks and real networks. Comparative experiments show that the MSCD algorithm has more efficient clustering performance and can reveal a clearer community.

Abstract:The frequency invariant beamforming belongs to constant beamwidth beamforming which can solve the problem of inconsistent beam response corresponding to different frequency components in a wideband signal. At present, most frequency invariant beamforming methods often have an invariant main lobe width as a constraint. When the number of array elements is determined, the formed beam sidelobe level often fails to meet the actual demand. Aiming at this problem, a new method to improve the beam sidelobe level is proposed by means of compressed sensing(CS). The method introduces the CS to preprocess the signal and uses second order cone programming (SOCP) for frequency invariant beamforming. Since CS recovery algorithm can accurately reconstruct the signals acquired by the compressed sampling matrix, the same beamforming performance can be obtained with fewer array elements. In other words, the method has a lower sidelobe level than the method based on SOCP in case of the same number of elements. The simulation results also show the effectiveness of the proposed method which has certain reference value in related engineering practice.

Abstract:The accurate sparse coefficients were hard to be obtained from the degraded signal due to theimage noise. Aiming at this problem, a double l1norm optimized image denoising algorithm via group sparse representation is studied. The algorithm constrains group sparse coefficients by using the l1norm and sparse residual of sparse representation of nonlocal similar image block as regularization item, and implements an optimal solution to the model for obtaining robust sparse coefficients by an effective iterative shrinkage algorithm. In addition, in order to further improve the performance of the image denoising algorithm, a Bayesian formula is used to derive a method for adaptively adjusting two regularization parameters. Extensive experimental results show that the proposed algorithm can suppress the artifacts while removing image noise, and preserve the detail of the image compared to many existing algorithms. Compared with the BM3D algorithm, our algorithm significantly improves the performance by 1.24 dB in PSNR.

Abstract:The traditional principle of synthetic aperture radio imaging is based on Shannon sampling theorem, which obtain the complete spectrum data with Shannon sampling and the inverse Fourier transform is used to generate the image. Due to the imaging equipment and external environmental factors, the spectrum data is accompanied by a large number of unreal signal, which causes a large amount of noise to be generated in the image, usually called a dirty image. In the field of radio astronomy, the related clean algorithm is usually used to process the dirty image to obtain a "clean" image. In order to reduce the sampling cost of the radio signal and obtain more "clean" radio image, based on radio interference sparse imaging and compressed sensing theory, we realize the reconstruction of the dirty image from the incomplete spectrum, and then removes the noise, orthogonal matching pursuit and feature sign algorithm is used to reconstruct the dirty image from the sparse spectrum and the noise is then removed by block-matching and 3-D filtering.

Abstract:We have performed theoretical investigations on the structure, equation of state (EOS), elasticity of the cubic ( space group of P4232, No: 208) and tetragonal ( space group of P42/nmcs, No: 137) Cd3As2 crystal by using the first-principles pseudopotential plane-wave method. The bulk modulus and its pressure derivation are obtained by fitting the energy–volume points to Birch–Murnaghan equation of state. Moreover, according to the Voigt–Reuss–Hill approximation, the elastic moduli of Cd3As2 are also successfully predicted. By employing the quasi-harmonic Debye model, the thermal expansion coefficient, bulk modulus, cell volume and heat capacity at different temperatures are also obtained.

Abstract:The effects of grain size on the deformation mechanisms of nano-polycrystal Cu and dual-phase nanostructured Cu/CuZr composites under tensile loading are studied by molecular dynamics method. The results show that for nano-polycrystal Cu with small grain size, the deformation mechanism is mainly dominated by grain rotation and grain boundary migration, accompanied by the nucleation and emission of a few dislocations. For nano-polycrystal Cu with large grain size, the plastic deformation mechanism is mainly dominated by the nucleation and growth of cracks. However, for the dual-phase nanostructured Cu/CuZr composites, the plastic deformation of amorphous phase plays a dominant role during plastic deformation, regardless of grain sizes. In addition, when the grain size becomes large, the grain boundary cracks also appear at the grain boundary of the composites, but the amorphous phase obviously hinders the nucleation and propagation of the cracks. The research shows that the introduction of amorphous phase can effectively enhance the plasticity of nano-polycrystal Cu.

Abstract:We use scattering scanning near field optical microscopy to investigate the near field response of tungsten ditelluride(WTe2). By using finite-dipole model we calculate the scattered signal ratio of sample to substrate and found that it can not be fully described by bulk property. This difference is most likely contributed to the decoupled layer on the bulk WTe2.Then we give possible explanations to the bright fringe at the sample edge. This work provides a reference for the optical research of topological materials in the future.

Abstract:Hemispherical coated glass beads are the basic reflective units of retroreflective materials. But, so far, the studies are only limited to the properties of individual glass bead, and have not yet involved synergy between adjacent beads during the retroreflective process. In fact, the presence of synergism makes the reflective properties of the entire film different from that of individual beads. In this paper, the retroreflective ray transmission process was comprehensively analyzed, and a numerical calculation program for glass bead array retroreflective materials was developed taking into account the structural characteristics of retroreflective materials. The variation of retroreflective efficiency with the density of micro beads, the refractive index of the material, and the incident angle of the light were calculated. The results show that the synergistic effect of the bead arrays manifests as inclination effect and shading effect. The former strictly follows this quantitative rule of "the incline factor ", whereas the role of the latter can be quantitatively represented by the shading factor. The inclination effect lonely works at small incident angle, while both inclination effect and shading effect work together when the incident angle is relatively large.

Abstract:This work reports the calculations of the physical properties of TiB2 under high temperature and high pressure using the first-principles method. The calculations include the structural parameter, elastic constants, bulk modulus, band structure, phonon dispersion, thermodynamic properties. These results are in agree well with other experimental and theoretical calculated values. By analyzing the E-V curves, the phonon dispersion curve, and the density of states (DOS), we prove that TiB2 is mechanically stable. From the results of B/G ratio and Poisson's ratio, the brittleness behavior of TiB2 is obtained. On the basis of the quasi-harmonic Debye model, we calculate the Debye temperature Θ and analyze the temperature and pressure dependences of the thermal expansion. The volumetric specific heat is very close to the Dulong-Petit limit at 1300 K. By analyzing the electron state density, it is found that TiB2 has metallic properties, the peak at Fermi level decreases, the pseudo gap widens, non-localization increases and covalent bond is enhanced as the pressure increases. All these results have proved that the crystal structure of TiB2 is stable.

Abstract:W-K alloy has many advantages, such as high melting point, the resistance to thermal shock, and excellent resistance to helium hydrogen plasma irradiation. The key is the formation of potassium bubbles which can stabilize the grain boundary, act as pinning point and refine grain of W-K alloy, thus the properties of materials can been greatly improved. Positron annihilation lifetime spectroscopy (PLAS) is extremely sensitive to the concentration and size of nanoscale defects. In the paper, the values of positron lifetime in W-K alloy at different potassium contents ware measured by the method of positron annihilation lifetime spectroscopy. According to the two-state capture model, the positron lifetime spectrum was fitted as two-lifetime component, and the data were processed and used to analyze the change of concentration and size of potassium bubble in the W-K samples.

Abstract:The reaction mechanism of benzaldehyde and 2-aminopyridine Cu(I)-catalyzed to form N-(pyridin-2-yl)benzamide were studied by density functional theory. The geometries of the reactants, transition states, intermediates and products were optimized at the PW91/DNP level. Vibration analysis was carried out to confirm the transition state structure. Four possible reaction pathways were investigated in this study. The result indicates that the CuI is better suitable catalyst for producing N-(pyridin-2-yl)benzamide through CuI and Cu2O of Cu(I)-catalyzed. By comparison, the reaction Re→IMA1→TSA1→IMA2→TSA2→IMA3→TSA3→IMA4→IM6→TS4→P is the main pathway, the activation energy of which is the lowest. IM6→TS4→P is the rate-limiting step, with the activation energy being 260.12 kJ/mol and the reaction heat being 93.01 kJ/mol. The dominant product predicted theoretically is in agreement with the experiment results.

Abstract:Soil colloids, as the most subtle and active part of the soil, play a major role in the accumulation of heavy metals in the soil. Study on the effect of different soil colloids on the adsorption-desorption behavior and the transformation of chemical forms of cadmium will help to understand the environmental chemical behavior of cadmium, which has a great significance to the remediation of cadmium pollution in regional farmland. In this study, smectite, kaolin, goethite, aluminum hydroxide and humic acid which colloids are commonly found in soil were collected to explore the adsorption characteristics of cadmium on different soil colloid. The following conclusions were obtained: (1) The adsorption of the five colloids to cadmium belongs to monomolecular adsorption. Smectite can quickly absorb a large amount of cadmium, but the adsorption of cadmium is unstable and the desorption rate is the highest. The cadmium desorption rates of humic acid and goethite are lower. Adsorption-desorption experiment results show the retained adsorption capacity: humic acid (41.38 mg/g) > goethite (24.95 mg/g) > kaolin (19.43 mg/g) > smectite (15.06 mg/g) > aluminum hydroxide (10.84 mg/g). (2) The species analysis results show that the cadmium adsorbed by smectite and kaolin mostly exists in exchangeable state, and the cadmium adsorbed by goethite and humic acid is relatively stable. Except for goethite, the residual state content is relatively low. The species analysis results are consistent with the results of adsorption-desorption experiment. (3) The degree of influence of pH on cadmium adsorption by five colloid is: humic acid > goethite > kaolin > smectite > aluminum hydroxide.

Abstract:Three coordination polymers ([Pr(TZI)(H2O)5]•5H2O (1), [Sm(TZI)(H2O)5]•5H2O (2) and [Nd(TZI)(H2O)5]•2H2O (3)) have been hydro/solvothermally synthesized by involving 5-tetrazolylisophthalic acid (H3TZI) as ligand and rare earth metal ions (Pr3+、Sm3+、Nd3+) as metal centers. Crystal structures characterized by powder X-ray diffraction (XRD) and X-ray single crystal diffraction showed that the three compounds have one-dimensional chain structure, and structure differences among the complexes have been discussed in detail. Meanwhile, the thermal stabilities of them are researched.

Abstract:Image analysis is closely related to image processing, computer graphics and other research contents, and overlaps with each other. The improved fuzzy C mean clustering algorithm with strong anti noise ability and neighborhood pixels is applied to the research of carbon fiber wood composites. The satisfactory results have been obtained through the test. After that the characteristic parameters of carbon fiber were extracted and a carbon fiber distribution parameter r was set up to distinguish the carbon fibers in the electron microscope. This study provides a convenient method for the identification of carbon fiber wood composites, and provides data support for the later construction of macro and micro models of carbon fiber wood composites.

Abstract:The influences of doping and stress on the electronic structure and optical properties of ZrO2 thin films were systematically studied by using the first-principles plane-wave ultra-soft pseudopotential method based on density functional theory. In this paper, the effect of Hf atom substitution doping on the physical properties of ZrO2 films is studied. The results show that Hf atom doping can reduce the band gap and density of states of ZrO2 films, which can reduce the surface defect charge and leakage current to some extent. The values of dielectric peak and absorption peak are significantly decreased after doping Hf atoms, and the waveforms of dielectric peak and absorption peak are narrowed, and the full wave at half maximum (FWHM) is significantly reduced. This paper also focuses on the physical properties and regularity of tetragonal ZrO2 films under different stresses. It is found that the compressive stress significantly regulates the band gap of the ZrO2 film and the band structures near the top of valence band and the bottom of the conduction band. After the stress is applied, the absorption range and absorption intensity of the absorption peak are significantly increased. The blue shift of the photon energy corresponding to the peak indicates that the absorption of ultraviolet light is enhanced with the increase of stress. In the low-energy infrared and visible light regions, the refractive index of ZrO2 film becomes larger after applying compressive stress, but in the ultraviolet region, the compressive stress causes the refractive index of ZrO2 film to increase first and then decrease. The above research results provide a theoretical basis for the design and application of ZrO2 thin film materials.

Abstract:Obtained a highresolution complex crystal structure of the androgen receptor (AR) and its response element (ARE) could provide a theoretical basis for drug target design for the treatment of prostate cancer. In this study, a prokaryotic expression vector of AR-DBD was constructed, and the protein was inducted to expression at 16 ℃ with 0.5 mmol/L IPTG for 24 h. In order to purify AR-DBD protein easily, the protein purification conditions were optimized by binding to ARE oligonucleic acids. Finally, we obtained the proteinnucleic acid complex crystal that exhibited short rodlike threedimensional structures with clear crystal edges. The proteinnucleotide complex crystals prepared in this study can be used for Xray diffraction analysis directly.

Abstract:To investigate the response mechanism under Microcystis aeruginosa stress provides reference value on improving application efficiency of duckweed in water pollution repair. In this study, we established a coculture system of Microcystis aeruginosa and Spirodela punctata with different concentration gradients, and measured biomass, total chlorophyll, antioxidant enzymes and microcystin. The main results showed as following: Spirodela punctata cocultivated with Microcystis aeruginosa at 3×108 cells/L, 6×108 cells/L concentration were enriched Microcystin(MCs) continually; the growth of Spirodela punctata was inhibited and the biomass decreased continuously in each group, whereas the fresh weight was increased in lowdose Microcystis aeruginosa (3×108 cells/L) after 6days’ cocultivation; the activities of different antioxidant enzymes were different under the stress of Microcystis aeruginosa, peroxidase (POD) and glutathione peroxidase (GSHPx) activities were significantly increased after 6days’ cocultivation, and superoxide dismutase (SOD) and catalase (CAT) activities were inhibited first while they were both improved after 12 days at 3×108 cells/L. In summary, the growth and development of Spirodela punctata under the stress of Microcystis aeruginosa was inhibited, but the antioxidant capacity of Spirodela punctata could be enhanced under the condition of lower concentration of Microcystis aeruginosa, and excessive concentration of Microcystis aeruginosa might lead to abnormal expression of antioxidant enzymes and affect the metabolism of cells seriously.

Abstract:In order to clarify the relationship between Astaxanaxin's antioxidant effect and cell apoptosis, cell survival rate, accumulation of reactive oxygen species, cell apoptosis, protein content and relative gene expression were detected by CCK-8, reactive oxygen probe staining, flow cytometry, western blotting, and realtime quantitative fluorescence PCR to explore the effect of astaxanthin pretreatment on oxidative stress induced by H2O2 in HeLa cells. The results showed that the cell activity of astaxanaxin pretreatment group was 29.54% higher than that of the control group, and it could reduce H2O2-induced reactive oxygen species to the control levels, meanwhile, it can also increase the Nrf2 protein expression by 3 times, and increase the relative expression of the catalase gene by 1.5 times. The results indicated that astaxanthin could effectively alleviate the oxidative stress of HeLa cells induced by H2O2, thereby inhibiting apoptosis.

Abstract:To study the functions of bHLH TFs in Brassica napus, five fulllength cDNA sequences of BnbHLH92 genes are cloned from Brassica napus by the homologous cloning method and named as BnbHLH92-1, BnbHLH92-2, BnbHLH92-3, BnbHLH92-4, BnbHLH92-5, respectively. And the length of the coding region for each gene is 738, 657, 684, 741, 717 bp, respectively. The qRTPCR result shows that BnbHLH92-1 gene is expressed in the root of the bolting stage and flowering stage as well as the two leaves stage, but the other BnbHLH92 genes mainly expressed in the roots of the bolting stage and the flowering stage. The expression of BnbHLH92 genes is significantly affected by abiotic stress, which increases the amount of genes expression. The expression level of five BnbHLH92 genes reach its highest under a low temperature stress for 4, 6, 6, 6 and 6 h, under a high temperature stress for 2, 6, 6, 8 and 4 h, under a salt stress for 6, 6, 24, 24 and 24 h, respectively. The expression of each BnbHLH92 gene is also increased in different degrees under ABA induction. It is found that there is an ABA response element (ABRE) on the promoter sequence of each BnbHLH92 gene.

Abstract:To explore the molecular mechanism of the regulation of PPARα level and lipidlowering in Tibetan tea aqueous extract, the prokaryotic recombinant vector pET32a-PTD-PPAR was constructed to express PTD-PPARα fusion protein with cellentering ability, and constructed of a highlipid cell model using hepatocyte Lo2 cell line. SDS-PAGE and Western blotting results indicated that PTD-PPARα fusion protein had a high purity and specificity, and it could enter L02 cells and reduce lipid deposition in L02 highfat cells. The L02 highfat cell model was treated with Tibetan tea aqueous extract for 24 h, lipid deposition analyzed by Oil red O staining showed that cell lipid deposition was significantly decreased; western blotting also showed PPARα protein levels increased significantly with a concentrationdependent manner. In conclusion, the results showed that the aqueous extract of Tibetan tea may inhibit the deposition of lipids in cells by regulating the level of PPARα protein and regulate lipid metabolism.

Abstract:In order to establish a rapid and accurate determination method for measurement of total flavonoids in bamboo leaves, a general colorimetric method was optimized by using the alkaline sample solution as the reference solution, using isoquertoside as the standard, and shortening the staining time after adding the staining reagent. The optimized colorimetric method reduced the measurement time by 1/3 while reducing the impurities interference and eliminating the measurement error caused by the rutin standard. Furthermore, the method provided good linearity and precision. The average recovery rate was 100.14%, and the RSD was 0.79%(n=5). The results showed that the optimized colorimetric method can be used for the determination of total flavonoids in bamboo leaves.

Abstract:The application of state-of-the-art artificial intelligence to the law has led to a promising area of interdisciplinary research: computational jurisprudence. By investigating legal relationships through simulation and modeling with transforming the legal information analysis to real-time online intelligent system, computational jurisprudence is not simply to simulate the methods of natural science, but a deep integration of computational thinking and legal thought. With distributed real-time computing, computational jurisprudence aims to reveal the intrinsic essence behind legal system to improve the judicial efficiency, promote legislative feasibility and also reduce the conflicts in legal system.