Experimental study on piping in sandy gravel foundations considering effect of overlying clay

The influence of the overlying clay on the progression of piping in the sandy gravel foundation of water-retaining structures is often neglected. In order to study this influence, an experimental investigation was conducted on a laboratory-scale model. It was discovered that the critical hydraulic gradient and the area of the piping tunnel increase when the overlying clay thickens. With a thicker clay layer, erosion of the sandy gravel below the clay layer occurs later, but, once the erosion starts, the erosion rate is very high and the average velocity of water seeping through the cross-section of the sandy gravel increases rapidly due to the low deformability of the thick clay layer. Furthermore, it was found that the progression of piping is a complicated and iterative process involving erosion of fine particles, clogging of pores, and flushing of the clogged pores. Two types of erosion have been identified in the progression of piping: one causes the tunnel to advance upstream, and the other increases the depth of the tunnel. The results show that the overlying clay is an important factor when evaluating piping in sandy gravel foundations of water-retaining structures.

Site testing campaign for the Large Optical/infrared Telescope of China:overview

The Large Optical/infrared Telescope(LOT)is a ground-based 12 m diameter optical/infrared telescope which is proposed to be built in the western part of China in the next decade.Based on satellite remote sensing data,along with geographical,logistical and political considerations,three candidate sites were chosen for ground-based astronomical performance monitoring.These sites include:Ali in Tibet,Daocheng in Sichuan and Muztagh-ata in Xinjiang.Up until now,all three sites have continuously collected data for two years.In this paper,we will introduce this site testing campaign,and present its monitoring results obtained during the period between March 2017 and March 2019.

Old stellar population synthesis:new age and mass estimates for Mayall II = G1

Mayall Ⅱ = G1 is one of the most luminous globular clusters （GCs） in M31. Here, we determine its age and mass by comparing multicolor photometry with theoretical stellar population synthesis models. Based on far- and near-ultraviolet GALEX photometry, broad-band UBVRI, and infrared JHKs 2MASS data, we construct the most extensive spectral energy distribution of G 1 to date, spanning the wavelength range from 1538 to 20 000A. A quantitative comparison with a variety of simple stellar population （SSP） models yields a mean age which is consistent with G1 being among the oldest building blocks of M31 and having formed within ～1.7 Gyr after the Big Bang. Irrespective of the SSP model or stellar initial mass function adopted, the resulting mass estimates （of order 10^7M⊙） indicate that GI is one of the most massive GCs in the Local Group. However, we speculate that the cluster＇s exceptionally high mass suggests that it may not be a genuine GC. Our results also suggest that G1 may contain, on average, （1.65±0.63） × 10^2L⊙ far-ultraviolet-bright, hot, extreme horizontal-branch stars, depending on the adopted SSP model. In addition, we demonstrate that extensive multi-passband photometry coupled with SSP analysis enables one to obtain age estimates for old SSPs that have similar accuracies as those from integrated spectroscopy or resolved stellar photometry, provided that some of the free parameters can be constrained independently.

Estimating the Metallicity of Old Star Clusters in M33

Based on the method proposed by Kong et al. and on the multi-color spectrophotometry by Ma et al., we estimate the metallicities of 16 old star clusters in the nearby spiral galaxy M33, ten of which are halo globular clusters. These old clusters are all metal poor, the range of metallicity ([Fe/H]) is from-0.14 to-2.12. In general, our results are consistent with those derived by other methods, such as integrated spectra and photometry, and our study confirms the reliability of the method of Kong et al.

Variable stars in the field of open cluster NGC 2126

We report the results of a time-series CCD photometric survey of variable stars in the field of open cluster NGC 2126. In about a one square degree field covering the cluster, a total of 21 variable candidates are detected during this survey, of which 16 are newly found. The periods, classifications and spectral types of 14 newly discovered variables are discussed, which consist of six eclipsing binary systems, three pulsating variable stars, three long period variables, one RS CVn star, and one W UMa or δ Scuff star. In addition, there are two variable candidates, the properties of which cannot be determined. By a method based on fitting observed spectral energy distributions of stars with theoretical ones, the membership probabilities and the fundamental parameters of this cluster are determined. As a result, five variables are probably members of NGC 2126. The fundamental parameters of this cluster are determined as： metallicity to be 0.008 Z, age log（t） = 8.95, distance modulus （m - M）0 = 10.34 and reddening value E（B - V） = 0.55 mag.

Expression of PYY, MTL and GAS in serum of IBS patients and their relationship with inflammatory response

Objective:Expression of PYY, MTL and GAS in serum of IBS patients and their relationship with inflammatory response.Methods: Using 100 IBS patients admitted to our hospital from November 2016 toApril 2018as the observation group and 100 normal persons in the same period as the control group, we observed the levels of serum PYY, MTL, GAS and expression of inflammatory factors in the two groups, and the correlation between different clinical symptoms of the disease group and serum PYY, MTL, GAS. The correlation analysis between serum PYY, MTL, GAS and inflammatory response in patients with disease and the influencing factors of patients with disease.Results: The expression levels of PYY, MTL, GAS and inflammatory factors in patients with diarrhea were significantly higher than those in control group, and the expression levels of PYY, MTL, GAS and inflammatory factors in patients with diarrhea were significantly higher than those in patients with constipation. The expression levels of PYY, MTL and GAS in patients with diarrhea and constipation were negatively correlated. There was a negative correlation between serum inflammatory factors and DIARRHEA-TYPE patients, but no correlation between Constipation-Type patients and inflammatory factors. Serum PYY, MTL and GAS were positively correlated with inflammatory reaction factors TNF-a, IL-6 and IL-8 in DIARRHEA-TYPE patients. Serum PYY, MTL and GAS levels in patients with DIARRHEA-TYPE patients could be regarded as independent risk factors for IBS.Conclusion: The serum levels of PYY, MTL and GAS in patients with diarrhea IBS were positively correlated with the expression of inflammatory factors, which had guiding significance for the diagnosis and treatment of IBS.

Improving mathematical model of burden distribution and correcting chute angle to cope with fluctuation of stock line

Accurate evaluations of the burden distribution are of critical importance to stabilize the operation of blast furnace.The mathematical model and discrete element method(DEM)are two attractive methods for predicting burden distribution.Based on DEM,the initial velocities of the pellet,sinter,and coke were calculated,and the velocity attenuations of the above three particles between the burden and the chute were analyzed.The initial velocity and velocity attenuation were applied to a mathematical model for improving the accuracy.Additionally,based on the improved model,a scheme for rectifying the chute angles was proposed to address the fluctuation of the stock line and maintain a stable burden distribution.The validity of the scheme was confirmed via a stable burden distribution under different stock lines.The mathematical model has been successfully applied to evaluate the online burden distribution and cope with the fluctuation of the stock line.

Mathematical model of burden distribution in bell-less top blast furnace

The burden distribution in the shaft of blast furnace is known to affect the gas distribution,heat transfer,and chemical reactions inside the furnace.However,the internal layer structure of burden in the shaft cannot be directly measured.Hence,a mathematical model for evaluating burden profile and layer structure was established.A sensitivity analysis based on the model was implemented to elucidate the effect of some factors on the burden distribution,including the stockline height and the mass of central coke.The results show that the width of funnel zone widens with the increase in stockline height,and the mass percentage of ore to coke in this zone slightly increases.Besides,the mass of central coke shows a significant influence on the width of coke channel,and 2%of batch mass of coke is recommended to implement central coke charging operation.The model has been indirectly verified by the gas temperature in operating blast furnace and successfully applied to online evaluate burden distribution.

Biochemical Properties and Inhibition Kinetics of Phosphatase from Wheat Thylakoid Membranes

A phosphetase that hydrolyses phosphate monoesters has been Isolated from wheat thylakold membranes. Biochemical properties and inhibition kinetics of the phosphatase were Investigated using several Ions, organlc solvents, and Inhlbltors. Wheat （Trltlcum aestivum L. cv. PH82-2-2） thylakold membrane phosphatase activity was activated by Mg^2＋, Ca^2＋, and Fe^2＋ and was inhibited by Mn^2＋ and Cu^2＋. For example, enzyme activity was acUvated 34.81% by 2 mmol/l. Mg^2＋, but was Inhibited 22.3% and 8.5% by 2 and 1 mmol/L Cu^2＋, respectively. Methanol, ethanol and glycol were all able to activate enzyme activity. Enzyme activity was activated 58.5%, 48.2%, and 8.7% by 40% ethanol, methanol and glycol, respectively. From these results, It can be seen that the degree of actlvetlon of the phosphetase was greatest for ethanol and the type of acUvatlon was uncompetltlve. Moreover, the activity of the thylakold membrane phosphetase was Inhibited by molybdate, vanadete, phosphate, and fluoride and the type of Inhibition produced by these elements was uncompetltlve, non-competitive, competltlve and mixed, respectively.

Effect of quaternary basicity on softening-melting behavior of primary slag based on magnesium flux pellet

It is generally accepted that the softening-melting properties of ferrous burden play a vital role in optimizing the shape and position of cohesive zone.The effect of quaternary basicity and atmosphere on softening,melting and permeation temperatures of primary slag based on magnesium flux pellet was investigated by visualization method.The mechanisms were analyzed utilizing thermodynamic calculation,X-ray diffraction analysis and electron probe microanalysis.The results indicated that the softening and melting temperatures of oxide samples increased by approximately 120℃with increasing quaternary basicity from 0.3 to 1.2 owing to the formation of slag phases with high melting point and solid Fe.Meanwhile,the difference between softening and melting temperatures decreased from 21 to 11℃.The permeation temperature was not affected by the quaternary basicity and fluctuated around a level of 1250 C,given that the permeation temperature depends on the wettability between slag and coke bed.On the other hand,as the ratios of CO/CO_(2) varied from 3/7 to 7/3,there were no significant differences in either the softening or melting temperatures,whereas the permeation temperature was increased from 1239 to 1271℃ since the reduction of FeO-bearing phases to solid Fe could decrease the wettability between slag and coke bed.