Search

Colletotrin A (1), a new 1,4-benzoxazine derivative, and eight known compounds, including two alkaloids (2-3), one acylamide (4), one benzaldehyde (5), and four sterols (6-9) were obtained from endophytic fungus Colletotrichum gloeosporioides B-142, which was isolated from Dracaena cochinchinensis. Among them, 1,2,3,4-tetrahydroquinoline-4,8-diol (2) was reported for the first time as natural product. The structure of compound 1 was elucidated with help of spectroscopic data including IR, UV, electronic circular dichroism (ECD) calculation, HRESIMS, 1D and 2D NMR (COSY, HSQC and HMBC). The antimicrobial activities were evaluated by disc diffusion method.

Objective To investigate the effect of LH level changes on the outcomes of controlled ovarian hyperstimulation (COH) and embryo transfer (ET) in gonadotropin-releasing hormone antagonist (GnRH-ant) protocol. Methods: A total of 721 patients undergoing GnRH-ant protocol COH for the first IVF/ICSI cycles were retrospectively analyzed. COH process were divided into 2 stages, before (stage 1) and after (stage 2) the GnRH-ant initiation, and each with 5 groups basing on LH levels: LH decreased more than 50% (A1, A2), decreased 25%-50% (B1, B2), change less than 25% (C1, C2), increased 25%-50% (D1, D2), and increased more than 50% (E1, E2). Results: There were no significant differences among groups of stage1 regarding COH and ET outcomes. For stage 2, the more obvious the decrease of LH level, the more the number of oocytes retrieved, mature oocytes, fertilized oocytes, embryos cleavaged and the numbers of embryo available (P

Additional file 1: Supplementary Table 1. The demographic data of the nearby counties and cities at the end of 2010. Supplementary Table 2. The type of self-harm behaviors before and during the pandemic. Supplementary Table 3. The type of violence before and during the pandemic.

Additional file 7: Table S3. Summary of pooled results regarding meta-regression.

Additional file 5: Table S1. Characteristic of the patients included.

Additional file 6: Table S2. Sensitivity analyses including biochemical variables.

The current popular methods for decision making and project optimisation in mine ventilation contain a number of deficiencies as they are solely based on either subjective knowledge or objective information. This paper presents a new approach to rank the alternatives using G1-coefficient of variation method. The focus of this approach is to use combination weighing, which is able to compensate for the deficiencies in index single weighing method. In the case study, an evaluation index system was established to determine the evaluation value of each ventilation mode to select the best development face ventilation mode. The result shows that the proposed approach is able to rank the alternative development face ventilation mode reasonably, the combination weighing method had the advantages of using both subjective and objective weighing methods by taking into consideration of both the experience and practical knowledge, and any possible changes in a scenario. This approach provides a more reasonable and reliable procedure to analyze and evaluate different ventilation modes.

Mn–CeOx/Zr-delaminated-clay has proven to be a promising low-temperature selective catalytic reduction (SCR) catalyst. To investigate the effects of alkali metals (potassium and sodium) on Mn–CeOx/Zr-delaminated-clay for the low-temperature SCR of NOx by NH3, fresh and alkali-deactivated Mn–CeOx/Zr-delaminated-clays were prepared under laboratory conditions. The SCR activity of each catalyst was measured for the removal of NO with NH3 in a fixed-bed flow reactor. The properties of the catalysts were characterized by XRD, H2-TPR, NH3-TPD, BET and XPS analyses. These results indicate that alkali metals seriously reduced catalytic activity, with potassium having a stronger deactivation effect than sodium. The addition of alkali metals to the catalysts lowered manganese oxide reducibility, allowed decrease of specific surface areas, increased Mn binding energy and lowered the number of acidic sites on the surface. Dissolution of Na, K from the catalysts by washing with water was found to be the best method for regenerating catalysts that were not greatly deactivated by alkali metals.

Accurate measurement and analysis of residual stress state in the SiCf/Ti composites are crucial to optimizing their fabrication process and to understanding their failure mode, but they are still a challenge. In this work, SiCf/C/Ti17 composites with~48% fiber volume fraction, consisting of W-core SiC fibers (~100 m in diameter), turbostratic C coating (~2.5 m in thickness) and Ti17 matrix, are prepared by consolidating precursor wires fabricated by matrix-coated fiber method through hot isostatic pressing at 920℃/120 MPa/2 h; these samples are used for measuring their stresses. It is noted that turbostratic C coating, a necessary diffusion barrier layer between SiC fiber and Ti17 alloy matrix, bears the residual stress caused by the mismatch of thermal expansion coefficients between fiber and matrix during consolidation. It is found that the graphene planes are almost parallel to the axial direction of SiC fibers in the turbostratic C coating revealed by high magnification transmission electron microscope, and thus G peak position of C coating would be sensitive to stress state. Accordingly, micro-Raman spectroscopy is first used to measure the G peak positions of C coating under stress and stress-free state in the SiCf/C/Ti17 composite, respectively. Based on the position shift of G band caused by residual stress, the axial residual compressive stress of SiC fiber in SiCf/C/Ti17 composite is calculated to be~705.0 MPa. For comparison, X-ray diffraction method is also adopted to measure the interplanar spacing values of the Ti17 alloy matrix in different directions to obtain the spatial strains. During measurement, -Ti (213) high-angle diffraction peak is chosen to reduce test error, and then the different interplanar spacing values of -Ti (213) are obtained by varying the values of in three different directions at =0, 45 and 90. As three-axis-stress model is employed, the residual tensile stress of Ti17 alloy matrix in the axial direction of SiCf/C/Ti17 composite is~701.3 MPa, which is transformed through linear elastic theory into the residual compressive stress of SiC fiber of~759.4 MPa. The similar results confirm that it is reliable to characterize the residual stress in the SiCf/C/Ti17 composite with high-texture turbostratic carbon by both the Raman spectroscopy and the X-ray diffraction method.

For two-dimensional unmagnetized dusty plasmas with many different dust grain species, a Kadomtsev–Petviashvili (KP) equation, a modified KP (mKP) equation and a coupled KP(cKP) equation for small, but finite amplitude dust-acoustic solitary waves are obtained for different physical conditions respectively. The influence of an arbitrary dust size distribution described by a polynomial expressed function on the properties of dust-acoustic solitary waves is investigated numerically. How dust size distribution affects the sign and the magnitude of nonlinear coefficient A (D) of KP (mKP) equation is also discussed in detail. It is noted that whether a compressive or a rarefactive solitary wave exists depends on the dust size distribution in some dusty plasmas.

Taking into account the combined effects of the external magnetic field, adiabatic dust charge fluctuation and collisions occurring between the charged dust grains and neutral gas particles (dust-neutral collisions), the dust-acoustic solitary waves in three-dimensional uniform dusty plasmas are investigated analytically. By using the reductive perturbation method, the Korteweg–de Vries (KdV) equation governing the dust-acoustic solitary waves is obtained. The present analytical results show that only rarefactive solitary waves exist in this system. It is also found that the effects of the wave vector along the z-direction, dust charge variation, collisional frequency, the plasma density, and temperature ratio can significantly influence the characteristics of low-frequency wave modes. Moreover, for the collisional dusty plasmas, there is a certain critical value μc of the plasma density ratio μ, if μ < μc, the width of the waves increases with μ, otherwise the width of waves decreases with μ.

A modified Zakharov–Kuznetsov equation for small but finite amplitude dust acoustic waves in a magnetized votex-like ion distribution dusty plasma is obtained in this paper. It seems that there are instability for a soliton under higher-order transverse perturbations in this system. There is a certain critical value 4λ0. If the ratio of the wave length of the higher-order perturbations to the width of the soliton is larger than this critical value, the solitary wave is unstable, otherwise it is stable.

We discuss the possible nonlinear waves of atomic matter wave in a Bose–Einstein condensate. One and two of two-dimensional (2D) dark solitons in the Bose–Einstein condensed system are investigated. A rich dynamics is studied for the interactions between two solitons. The interaction profiles of two solitons are greatly different if the angle between them are different. If the angle is small enough, the maximum amplitude during the interaction between two solitons is even less than that of a single soliton. However, if the angle is large enough, the maximum amplitude of two solitons can gradually attend to the sum of two soliton amplitudes.

We theoretically study the electron detachment of negative hydrogen ions in a three-cycle linearly polarized laser field with a wavelength of 2150 nm in the context of the strong field approximation (SFA). The numerical integration and the saddle-point (SP) methods are both used in our calculations. The results show that both the energy spectra and the momentum spectra of the photoelectrons detached from negative hydrogen ions, obtained from these two methods, accord very well with each other for the laser intensities of 1.31011 W/cm2 and 6.51011 W/cm2, respectively. It is found that there is an obvious stripe-like structure along the vertical direction of the momentum spectra when the laser intensity is 6.51011 W/cm2. To explore the main origin which leads to the specific structures of the momentum spectra, we divide the interferences of the electronic wave packets emitted at different times during the laser pulse into the intra-cycle interference and the inter-cycle interference based on the SP method. Inter-cycle interference arises from the coherent superposition of electron wave packets released at complex times during different optical cycles, whereas intra-cycle interference comes from the coherent superposition of electron packets released in the same optical cycle. It is found that when only considering the inter-cycle interference, the main structures of the momentum spectra accord well with the above-threshold detachment (ATD) rings, which indicates that the inter-cycle interference corresponds to ATD rings of the photoelectron spectrum. But when only considering the intra-cycle interference, there are stripe-like structures with left-right asymmetry along the vertical direction of the momentum spectra. So the main structures of the momentum spectra of the photoelectrons are attributed to the interplay of the intra-and inter-cycle interferences. In addition, to intuitively explain the reason why the momentum spectra depend on the intensity of the laser field, we analyze the influence of the intensity of the laser field on the inter-cycle interference of quantum wave packets. It is found that the phase difference of the inter-cycle interference depends on the intensity of the laser field, which may lead to the difference among the momentum spectra of the photoelectrons at different laser intensities. Moreover, the influences of the intra-and inter-cycle interferences on the energy spectrum of the photoelectrons are also analyzed. It is found that the main oscillatory patterns and the peak positions of the energy spectra are mainly determined by the inter-cycle interference. Finally, the effects of the duration of laser pulse on the intra-and inter-cycle interferences are discussed. It seems that the main structures of the momentum spectra accord well with the ATD rings in multi-cycle laser pulses. So it is concluded that in multi-cycle laser pulses, the inter-cycle interference dominates while the intra-cycle interference is suppressed. The work in this paper is meaningful for further understanding the quantum interference effect and the optical control of the laser-induced photodetachment of negative ions.

Internet has infiltrated into every aspect of our lives. Accurate topological modeling is essential to improve Internet performance in many research areas, such as protocols design, routing and searching algorithm, virus spreading protection, and node failure effect. Based on the power-law characteristic of AS-level Internet topology, a time-varying evolving Internet topology model is proposed by applying dynamic rates in node growing, different level link connecting and link disconnecting in modeling process. Node degree distribution, average clustering coefficient and average node distance of the model match Internet topology corespondent parameters. An Internet topology with any given node number within span can be easily built by this model.

To present the shape and ore grade distribution of orebody in three dimensional space, and apply visualization to ore resources evaluation and analysis, an interactive visualization system for orebody modeling and grade estimation were developed. A group of sophisticated algorithms were utilized to integrate the orebody surface model and block model to a new scheme of hybrid model. Orebody surface model was reconstructed from planar contours. To convert the complex surface model to block model, an octree was used as data structure, OBB trees and Feito-Torres algorithm were employed respectively to implement intersection test and inclusion test of a block and surface model. Ore grade of blocks within block model were estimated by geostatistical techniques. An example of a copper mine has been applied to the visualization system is presented. This system can be a basic requirement for orebody modeling and facilitates the understanding of ore resource under the earth. Users of this visualization system can find that its strengths lie in simplicity of complex orebody modeling and increased availability of important information in 3D space.

Algorithms for Boolean operations using BSP trees and other algorithms have problems with efficiency and robustness. In order to improve the speed and correctness of operations, a new algorithm for Boolean operations on polygonal meshes was presented. In this algorithm, a fast collision detection algorithm based on oriented bounding box (OBB) was employed, which speed up the intersection test between every two triangles of two different polygonal meshes. After getting the intersection segments, the polygons can be obtained from intersected triangles and intersection segments, then establish the intersection region. Finally, the ultimate result was obtained by acceptance or rejection for the other meshes based on intersection region and the neighborhood of these meshes. In this algorithm, orientability, topology and other geometric characteristics are made full use of. The result shows that the algorithm is efficient and robust. Furthermore, it can apply to both closed meshes and open meshes.

Based on the meaning of Panel Data, regression model and its specific estimation method of Panel Data are introduced. Combined with the actual situation of farmland in Jiangsu Province, socio-economic factors affecting the farmland change is taken as the explanatory variables, such as total population, regional GDP, agricultural output value, total investment of fixed asset, total retail sales of social consumer goods, per capita disposable income of urban residents, and per capita income of farmer. And farmland is taken as the explained variable. According to the Panel Data of 13 cities in Jiangsu Province, Fixed Effect Model of fixed coefficient and variable intercept is selected based on the result of Hausman Test. This model is also used to construct the farmland socio-economic model of 13 cities in Jiangsu province. Result shows that population is the most important driving force factor of farmland change in Jiangsu Province; socio-economic factors have relatively weaker fixed effects on farmland; regression coefficient of agricultural output is not significant; and model coefficient of GDP reflects a different economic meaning from the reality. Thus, this model is generally significant from an economic sense.

The electron detachment of negative hydrogen ions exposed to a few-cycle linearly polarized laser pulse is investigated in the context of the strong field approximation evaluated by the saddle-point method. The results show that the angular distributions of the laser-induced photoelectron obtained by the saddle-point method are in good agreement with both the experimental results and the numerical-integration results. More importantly, we show that the unusual maximum in the angular distributions of photoelectrons for negative hydrogen ions can be explained by the quantum interference effect based on the saddle-point method.