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[Objective] In order to explore the changes of vegetation communities under different grazing intensities in grassland, the effects of community characteristics on soil aggregates were analyzed. [Methods] Taking the controlled grazing experimental area of Xilamuren desert steppe as the research object, the characteristics of vegetation community and soil aggregates under light grazing (LG), moderate grazing (MG), heavy grazing (HG), and no grazing (CK) and their relationship were analyzed by field investigation and indoor analysis, and the effects of plant community changes on soil aggregates were revealed. [Results] (1) The Shannon-Wiener diversity index (H′) and Simpson dominance index (D) of LG were significantly lower than those of other grazing intensities (p

To improve the liquefaction resistance of calcareous sand foundations, microbially induced calcium carbonate precipitation (MICP) technology and fiber reinforcement technology was combined to treat the calcareous sand sampled from the South China Sea. Based on dynamic triaxial tests, the dynamic behaviors of MICP-treated and fiber-reinforced calcareous sand, including dynamic strain, dynamic pore pressure, stress−strain hysteresis loop and dynamic modulus of elasticity, were analyzed. Then, the strengthening mechanism of MICP and fiber on the mechanical properties of the treated calcareous sand was explored from the microscopic point of view, based on the scanning electron microscope (SEM) test results. The results show that: (1) MICP could improve the deformation and liquefaction resistance of calcareous sand. Compared with the untreated specimen, the dynamic strain and dynamic pore pressure of calcareous sand treated by MICP decreased by 95.74% and 92.46%, respectively. (2) The addition of fibers further improved the reinforcement effect of MICP. Compared to the MICP-treated samples, the dynamic strain and dynamic pore pressure of MICP-treated and fiber-reinforced specimens decreased by 74.32% and 74.18%, respectively. (3) Combined MICP treatment and fiber reinforcement technology improved the deformation and liquefaction resistance of calcareous sand subjected to cyclic loading by reducing the intensity of cyclic activity and energy dissipation, increasing the dynamic modulus of elasticity and reducing its attenuation rate. (4) The results of the SEM test showed that MICP treatment and fiber reinforcement had a synergistic effect on the improvement of the dynamic behaviors of calcareous sand. The addition of fibers provided more spots for bacterial adhesion and promoted the formation of calcium carbonate crystals, which not only increased the bonding strength between sand particles, but also enhanced the constraint of fiber network by fixing fibers and sand particles together.

Modulated laser absorption spectroscopy is an ideal technique for evaluating flow-field parameters and determining flow-field quality by measuring the atoms dissociated in high-temperature environments. However, to obtain the absolute number density of atoms in the flow field, it is necessary to compare the measured modulated absorption spectroscopy signal with a known atomic concentration and establish a quantitative relationship through concentration calibration. Nevertheless, it remains a challenging task to prepare transient atomic samples with known concentrations that meet the calibration requirements. This study utilized the alternating-current glow discharge technique to dissociate oxygen in the air flow, resulting in the continuous generation of oxygen atoms. The absolute number densities of the generated oxygen atoms were determined by measuring the direct absorption spectra of centered on 777 nm for oxygen atoms. The number densities of the generated atoms were finely tuned by adjusting the discharge parameters. Throughout the 120-min continuous operation of the discharge system, the concentration of excited-state oxygen atoms remained stable within the range of (2.51 ± 0.02) × 108 cm−3, demonstrating the remarkable stability of the transient atomic concentration generated by the glow discharge plasma. This observation suggests that the generated atoms can be utilized as a standardized atomic sample of known concentration for absolute concentration calibration purposes.

Evaluating the laser quality accurately is one of the most important and fundamental physical issues for laser sources, and the beam quality of lasers from the large mode area few-mode fibers have been haunted by the presence of high order mode for many years. This paper presents a modification to the M2 factor, which can be used to evaluate the mode content of fiber lasers accurately and efficiently, no matter whether the fiber modes are superposited coherently or incoherently. By mathematical derivation, the origin of the influence of relative phase on the M2 factor has been determined mathematically. A modification to the second moment of the beam intensity profile has been proposed, which eliminates the impact of uncontrollable relative phase on the second moment, and subsequently restores the one-to-one mapping between mode content and M2 factor even for coherent superposition cases. Also presented are the results of numerical simulations, which support the validity of the modified M2 factor to evaluate the mode content of the high power fiber lasers. With modified M2 factor being less than 1.1, the power fraction of LP11 mode content is unique and determined to be less than 3%.

Objective To explore the protective effect of β-caryophyllene (BCP) on cerebral ischemia-reperfusion (I/R) rats and related mechanism. Methods SD rats were randomized into sham operation group, I/R group, and low-, medium- and high-dose BCP groups (102, 204 and 408 mg·kg-1), Jagged1 (Notch1 agonist, 50 mg·kg-1 in 3 h before I/R injury)+BCP group, and Jagged1 group. The treatments were given to the corresponding rats through intragastric infusion. In 7 d later, SD rat CIR model was established with suture-occlusion, with ischemia for 1.5 h followed by reperfusion for 48 h. The infarct volume and neurobehavioral score were measured; Western blotting was used to detect the cerebral protein levels of Notch1, NF-κB p65, NF-κB p-p65 and Hes1; HE staining was applied to observe the number of dead cells, and ELISA was employed to detect the changes of TNF-α and IL1-β contents in the ischemic hippocampus. Results BCP treatment could significantly improve the neurological deficit, reduce the infarct volume, down-regulate the protein levels of Notch1, NF-κB and Hes1 in the hippocampus (P < 0.05), reduce the releases of TNF-α and IL-1β (P < 0.05), and attenuate the death of hippocampal neuronal cells in the rats after cerebral I/R injury. Comparing the simple Jagged1 intervention group, Notch1 agonist, Jagged1, could antagonize the therapeutic effects of BCP. Conclusion BCP can attenuate cerebral I/R injury in rats, and exerts its protective effect probably through inhibiting Notch1/NF-κB signal axis to reduce the release of inflammatory factors.

Objective To investigate the protective effect of β-caryophyllene (BCP) against ischemic stroke injury in mice and clarify whether such protective effects are associated with miR-183 and nuclear factor-κB (NF-κB) expression. Methods Ninety male C57BL/6 mice were randomized equally into 3 groups, namely the sham-operated group, ischemia-reperfusion (I/R) model group, and BCP (72 mg/kg) pretreatment group. The mice in the latter 2 groups were subjected to middle cerebral artery occlusion for 60 min followed by reperfusion for 24 h. The neurological deficits and infarct volume of the mice were measured, and the pathological changes in the brain tissues were observed using HE and Nissl staining. The expression of miR-183, NF-κB, p-NF-κB, interleukin-1β (IL-1β), and IL-6 in the brain were detected, and the targeting relationship between miR-183 and NF-κB was determined. In the in vitro experiment, the cortical neurons isolated from the brain of neonatal mice were divided into normal group, oxygen-glucose deprivation (OGD) group, and OGD group with 10 μmol/L BCP pretreatment. Immunofluorescence assay was employed for morphological observation of the neurons, and the cell injury was assessed with lactate dehydrogenase (LDH) leakage assay. The expression levels of miR-183, IL-1β, IL-6 and NF-κB in the neurons were measured. Results In the mouse models of ischemic stroke, BCP pretreatment significantly improved neurologic deficit score, reduced the infarct volume, lessened pathological changes of the brain tissue, and decreased the number of Nissl-positive cells in the cortex (P < 0.05). BCP pretreatment significantly upregulated the expression of miR-183 in the brain tissues of the mice (P < 0.05). In the in vitro experiment, BCP pretreatment produced obvious protective effect on neurons and significantly lowered neuronal death rate following OGD (P < 0.05). BCP treatment significantly upregulated the expression of miR-183, inhibited NF-κB activation and lowered the expressions of inflammatory factors in the neurons (P < 0.05). Conclusion BCP protects the brain tissues against ischemic stroke injury by upregulating the expression of miR-183, which inhibits NF-κB activation and lowers the release of inflammatory factors to alleviate inflammation in the brain.

Photonic crystal is a kind of ordered material which consists of two or more periodic arranged refractive index materials, and the propagation of light can be controlled by changing its average refractive index or lattice spacing. The molecularly imprinted photonic crystal chemical sensors based on the combination of responsive photonic crystal structure and molecular imprinting technique have attracted research interests due to their strong specificity, high sensitivity and self-expression ability, which also provide a novel strategy for the trace detection. In this review, the two- and three-dimensional photonic crystal sensor materials were introduced, and the preparation, properties and applications of molecular imprinted photonic crystal(MIPC) were reviewed. The future research focus such as the improvement of resolution and repeatability of MIPC visual detection materials was analyzed and prospected at last.

C21H28N6O3B2F8, orthorhombic, Pccn (no. 56), a = 17.7949(19) Å, b = 9.3979(10) Å, c = 15.3455(16) Å, V = 2566.3(5) Å3, Z = 4, Rgt(F) = 0.0567, wRref(F2) = 0.1846, T = 296(2) K.

The effects of different concentrations of salt and alkali on root physiology and photosynthesis in oat (Avena sativa L.) at anthesis were compared. Treatment with salt and particularly with alkali, decreased yield and grain weight. Both alkali and salt treatments decreased the photosynthetic rate (Pn), stomatal conductance and chlorophyll content, with the effect on Pn and the chlorophyll content more marked after treatment with alkali. The decrease in Pn induced by salt and mild alkali (50 mmol L-1) contributed to a decrease in stoma opening. Under moderate and severe concentrations of alkali (100 and 150 mmol L-1 respectively), other factors rather than stoma closure were responsible for limiting Pn. The transpiration rates (Tr) in alkali-treated plants were higher than in salt-treated plants. We also observed decreases in both root volume and root dry weight, and increases in root activity in alkali- and salt-treated plants. Severe alkali and salt concentrations (150 mmol L-1) decreased the root-shoot ratio. A positive correlation between yield and root dry weight and a negative correlation between root activity and Pn were observed. Alkali and salt treatments increased superoxide dismutase (SOD) and peroxidase (POD) activities and the malondialdehyde (MDA) content, but decreased catalase (CAT) activity. Yield was negatively correlated with MDA, and the MDA content was greater under alkali treatments than after salt treatment. We conclude that alkali treatments had more severe effects on oat plants at anthesis than salt treatments.

This study aims to explore the relationship between locus of control, grit, self-esteem and mental health among college students. A questionnaire survey was used to conduct a study on the mental health of 923 E-learning college students from 10 universities in Guangxi, China. In this study, Pearson correlation analysis was used to test the correlation between the study variables, and Bootstrap was used to test the mediating effect and effect ratio of grit and self-esteem. The results show that, locus of control, grit, and self-esteem can predict the mental health of college students. Grit plays a mediating role between locus of control and mental health; self-esteem plays a mediating role between locus of control and mental health; grit and self-esteem have a chain mediating effect between locus of control and mental health. Specifically, internal locus of control can effectively prevent college students from mental health problems through the chain mediation effect of grit and self-esteem. Powerful others and opportunity as the external locus of control will not only reduce the grit and self-esteem of college students, but also lead to more psychological problems. These research results provide suggestions to the university management on how to manage the mental health of E-learning students, especially those with psychological problems.

Abstract In this paper, we experimentally validate a tiled-aperture conformal projection system with the largest array filling factor and element beam truncation factor to the best of our knowledge. The conformal projection system, which is made up of a hexagonal adaptive fiber-optics collimator (AFOC) array with the proximate ideal intensity distributions, is fabricated and the performance of output beam is tested and evaluated properly and carefully. Both of the active phase-locking control and precise tip-tilt control are implemented successfully in the CBC of the hexagonal seven-beam-array. Experimental results show a large energy proportion (47%, which increases by over 10% comparing with the previously demonstrated largest value) in the central lobe is achieved and the residual phase error is lower than λ/27. When the AFOC array performs, the precise tilt control makes the combining beams overlap well and the average normalized metric value is improved from 0.336 without control to 0.947 with both of active piston and tip-tilt phase controls while the fringe contrast increases from 19% to more than 91% correspondingly. This work presents a promising structure for the achievement of large energy proportion in the central lobe in high power fiber laser CBC systems.

To understand the knowledge of liner thermal expansion and thermal expansion coefficient of Q450NQR1 casting steel, dilatometry experiments were performed at two different cooling rates of 5℃·min-1 and 20℃·min-1. A mathematical model was developed to quantitatively extract the kinetic information of austenite transformation based on the concept of average atomic volume. The model was verified by microstructure examinations, indicating that the model was appropriate to describe the behavior of austenite transformation and could be applied to multi-phase transformations during steel continuous casting. The influence of cooling rate on the austenite transformation was discussed with the model. it is found that, with increasing cooling rate, two peaks associated to the precipitation of ferrite and pearlite on the thermal expansion coefficient curve shifted towards a lower temperature region with higher values. As the cooling rate increases from 5℃·min-1 to 20℃·min-1, the initial temperatures of ferrite and pearlite precipitation decrease by 32℃ and 37℃, and the final volume fractions of ferrite and pearlite gradually change from 0.894 and 0.106 to 0.945 and 0.055, respectively.