Cameron-Liebler sets for maximal totally isotropic flats in classical affine spaces

Let $ACG(2\nu,\mathbb{F}_q)$ be the $2\nu$-dimensional classical affine space with parameter $e$ over a $q$-element finite field $\mathbb{F}_q$, and ${\cal O}_{\nu}$ be the set of all maximal totally isotropic flats in $ACG(2\nu,\mathbb{F}_q)$. In this paper, we discuss Cameron-Liebler sets in ${\cal O}_{\nu}$, obtain several equivalent definitions and present some classification results.Comment: 25 page

A Survey on the Cultivation of College Students’ Audience Awareness in English Writing

The strength of audience awareness has a great influence on the content selection, expression and writing techniques of the article. Therefore, the cultivation of the students’ audience awareness in writing becomes one of the key factors that determine the qualities of the students’ compositions. This thesis conducts a questionnaire and interviews on college students from the four grades of Nanchang Normal University in order to reveal the college students’ cognitive status and attitude of audience awareness. Based on the status quo, this thesis analyzes the possible causes of this situation from two aspects: the teachers’ carelessness on audience awareness and overly concern with writing skills, and the students’ shortage of language ability and logical thinking ability and their excessive attention to writing skills. For these reasons, this thesis proposes corresponding countermeasures: in the English writing class, the reader's awareness should be emphasized; the theme of the article needs to be much closer to life; students are supposed to create imaginary readers in writing; the method of readers' feedback should be fully utilized. The use of these strategies will effectively help college students cultivate audience awareness in English writing

Design and research of hydraulic cylinder precise control test system

The position deviation after the continuous action of the hydraulic support in the fully-mechanized mining face affects the mining efficiency of the shearer. In view of the above problems, the mechanism of the hydraulic system of the fully-mechanized mining face is analyzed, the coupling relationship between the system pressure, flow and the displacement of the hydraulic cylinder is established, and a hydraulic cylinder precise displacement test platform with emulsion/pure water as the transmission medium is designed and built, which can carry out eccentric load and lateral load experiments of the test hydraulic cylinder. The test platform is composed of hydraulic test system, oil pressure regulation system, electrical control system, data acquisition system, upper computer software system, loading test bench, etc. The oil pressure regulation mechanism adjusts the working attitude of the hydraulic cylinder, the data acquisition system monitors and tests the pressure, flow, displacement, temperature and other data of the hydraulic cylinder in real time, and the loading test bench equates the hydraulic support, scraper conveyor and shearer as adjustable weight. Data acquisition frequency of the hydraulic cylinder precise control test system is 2 000 Hz, the nominal pressure is 31.5 MPa, the nominal flow is 400 L / min, the test hydraulic cylinder has a cylinder diameter of 100-240 mm, a stroke of 400-1 800 mm, and the working resistance is larger than 100 kN, which can achieve the working mechanism of the hydraulic cylinder under variable working conditions. When the system flow is 126 L/min, the displacement control error of the tested hydraulic cylinder is close to 20%; when the system flow is 50 L/min, the displacement control error of the tested hydraulic cylinder is stable within 7%. The experimental results show that the transient action of hydraulic cylinder extension and retraction can be ignored in the working process, and the displacement control error is mainly caused by the response delay of valve control components, and the control error increases linearly with the increase of system flow, which verifies the feasibility of the high flow rapid action and small flow precise regulation control scheme of the two speed pressure regulating valve. The hydraulic cylinder precise control test system is applicable to the research on the precise control of hydraulic cylinder and the coordinated control of hydraulic cylinder cluster, and provides an experimental method for realizing the precise control of hydraulic support in high-pressure and large flow fully-mechanized mining face

Experimental Investigation on OSB Webbed Laminated Bamboo Lumber Box Shaped Joists

A novel bamboo-wood box beam was introduced in this paper, which consisted of laminated bamboo lumber flanges and OSB webs. Four-point bending tests were conducted on composite beams to investigate the effects of shear span ratio and stiffeners on failure mode and strength. The results showed that the composite beams with shear span ratio less than two failed in web shear failure, but for the others, the beams failed in twist and delamination of OSB in flanges. The load carrying capacity of beams decreased with the increase of shear span ratio. However, the mechanical performance of beams can be improved moderately by the presence of stiffeners, and theultimate bearing capacity and initial stiffness was increased by 16.5% and 13.1% respectively

Enhancement of Calcium Chelating Activity in Peptides from Sea Cucumber Ovum through Phosphorylation Modification

Recently, phosphorylation has been applied to peptides to enhance their physiological activity, taking advantage of its modification benefits and the extensive study of functional peptides. In this study, water-soluble peptides (WSPs) of sea cucumber ovum were phosphorylated in order to improve the latter’s calcium binding capacity and calcium absorption. Enzymatic hydrolysis methods were screened via ultraviolet-visible absorption spectroscopy (UV–Vis), the fluorescence spectrum, and calcium chelating ability. Phosphorylated water-soluble peptides (P-WSPs) were characterized via high-performance liquid chromatography, the circular dichroism spectrum, Fourier transform infrared spectroscopy (FTIR), UV–Vis spectroscopy, surface hydrophobicity, and fluorescence spectroscopy. The phosphorus content, calcium chelation rate and absorption rate were investigated. The results demonstrated that phosphorylation enhanced the calcium chelating capacity of WSPs, with the highest capacity reaching 0.96 mmol/L. Phosphate ions caused esterification events, and the carboxyl, amino, and phosphate groups of WSPs and P-WSPs interacted with calcium ions to form these bonds. Calcium-chelated phosphorylated water-soluble peptides (P-WSPs-Ca) demonstrated outstanding stability (calcium retention rates > 80%) in gastrointestinal processes. Our study indicates that these chelates have significant potential to develop into calcium supplements with superior efficacy, bioactivity, and stability

Hypermethylation of miR-338-3p and Impact of its Suppression on Cell Metastasis Through N-Cadherin Accumulation at the Cell -Cell Junction and Degradation of MMP in Gastric Cancer

Background/Aims: MicroRNAs (miRNAs) have been well studied in human carcinogenesis and cancer progression. Our previous study showed the down-regulation of miR-338-3p expression in human gastric cancer (GC). However, the reasons of this dysregulation remain largely unclear. Methods: Bisulfite sequence analysis was performed to explore the methylation status of the promoter region of miR-338-3p. Cell wound-healing and transwell assays were performed to examine the capacity of cell migration and cell interaction. A dual-luciferase reporter was used to validate the bioinformatics-predicted target gene of miR-338-3p. Western blotting, RNA interference, and immunofluorescence (IF) were used to evaluate the expression of MMPs and the location of N-cadherin to determine the mechanism underlying miR-338-3p-induced anti-tumor effects. Results: miR-338-3p was epigenetically silenced, and this loss of expression was significantly correlated with the Borrmann Stage in GC. Restoring miR-338-3p expression in BGC-823 cells inhibited cell migration and invasion. Moreover, Ras-related protein (Rab-14) and Hedgehog acyltransferase (Hhat) were identified as direct targets of miR-338-3p. Both enforced expression of miR-338-3p and small interfering RNA induced Rab14-mediated accumulation of N-cadherin in the cell -cell junctions or Hhat-associated matrix metalloproteinase (MMP) degradation, which may underline the metastasis defects caused by loss of miR-338-3p in GC. Conclusion: These data indicate that miR-338-3p functions as a tumor suppressor in GC, and that the hypermethylation status of its CpG island might be a novel potential strategy for treating GC

Fluorescent Gold Nanoprobes for the Sensitive and Selective Detection for Hg2+

A simple, cost-effective yet rapid and sensitive sensor for on-site and real-time Hg2+ detection based on bovine serum albumin functionalized fluorescent gold nanoparticles as novel and environmentally friendly fluorescent probes was developed. Using this probe, aqueous Hg2+ can be detected at 0.1 nM in a facile way based on fluorescence quenching. This probe was also applied to determine the Hg2+ in the lake samples, and the results demonstrate low interference and high sensitivity

GAMA/G10-COSMOS/3D-HST: The 0<z<5 cosmic star-formation history, stellar- and dust-mass densities

We use the energy-balance code MAGPHYS to determine stellar and dust masses, and dust corrected star-formation rates for over 200,000 GAMA galaxies, 170,000 G10-COSMOS galaxies and 200,000 3D-HST galaxies. Our values agree well with previously reported measurements and constitute a representative and homogeneous dataset spanning a broad range in stellar mass (10^8---10^12 Msol), dust mass (10^6---10^9 Msol), and star-formation rates (0.01---100 Msol per yr), and over a broad redshift range (0.0 < z < 5.0). We combine these data to measure the cosmic star-formation history (CSFH), the stellar-mass density (SMD), and the dust-mass density (DMD) over a 12 Gyr timeline. The data mostly agree with previous estimates, where they exist, and provide a quasi-homogeneous dataset using consistent mass and star-formation estimators with consistent underlying assumptions over the full time range. As a consequence our formal errors are significantly reduced when compared to the historic literature. Integrating our cosmic star-formation history we precisely reproduce the stellar-mass density with an ISM replenishment factor of 0.50 +/- 0.07, consistent with our choice of Chabrier IMF plus some modest amount of stripped stellar mass. Exploring the cosmic dust density evolution, we find a gradual increase in dust density with lookback time. We build a simple phenomenological model from the CSFH to account for the dust mass evolution, and infer two key conclusions: (1) For every unit of stellar mass which is formed 0.0065---0.004 units of dust mass is also formed; (2) Over the history of the Universe approximately 90 to 95 per cent of all dust formed has been destroyed and/or ejected