Computation of elastic properties of 3D digital cores from the Longmaxi shale

The dependence of elastic moduli of shales on the mineralogy and microstructure of shales is important for the prediction of sweet spots and shale gas production. Based on 3D digital images of the microstructure of Longmaxi black shale samples using X-ray CT, we built detailed 3D digital images of cores with porosity properties and mineral contents. Next, we used finite-element （FE） methods to derive the elastic properties of the samples. The FE method can accurately model the shale mineralogy. Particular attention is paid to the derived elastic properties and their dependence on porosity and kerogen. The elastic moduli generally decrease with increasing porosity and kerogen, and there is a critical porosity （0.75） and kerogen content （ca. ≤3%） over which the elastic moduli decrease rapidly and slowly, respectively. The derived elastic moduli of gas- and oil-saturated digital cores differ little probably because of the low porosity （4.5%） of the Longmaxi black shale. Clearly, the numerical experiments demonstrated the feasibility of combining microstructure images of shale samples with elastic moduli calculations to predict shale properties.

系统

在Fedora Core3中，哪些程序会被SELinux(Security-Enhenced Linux)保护?

应用问答

我在IBM R50e笔记本上安装了Fedora Core3。在使用投影仪时，图像只能在本机或投影仪上显示，不能两边同时显示，是什么原因?如何解决?在笔记本上配置无线网卡，已经安装好了ipw2200内核模块，并重新启动了系统，系统仍然无法使用无线上网。我使用Debian sid／2．6．10内核，好不容易在PC上安装上Solaris 9 x86版本，但是系统启动后的图形界面很难看，分辨率低，像素也低，好像是16色的样子。另外，声卡没声音。我的电脑是845G的主板，声卡是集成的……

更改Fedora Core 3 GNOME的打开方式

很多朋友抱怨说GNOME2．6的文件管理器行为古怪，因为文件夹总要在新窗口里打开，所以经常要关闭一大堆窗口。如果想要用原来GNOME2．4版的风格，就只能使用“浏览文件系统”(nautilus—browser)。

Reconstruction of 3-D digital cores using a hybrid method

A 3-D digital core describes the pore space microstructure of rocks. An X-ray micro CT scan is the most accurate and direct but costly method to obtain a 3-D digital core. In this study, we propose a hybrid method which combines sedimentation simulation and simulated annealing （SA） method to generate 3-D digital cores based on 2-D images of rocks. The method starts with the sedimentation simulation to build a 3-D digital core, which is the initial configuration for the SA method. We update the initial digital core using the SA method to match the auto-correlation function of the 2-D rock image and eventually build the final 3-D digital core. Compared with the typical SA method, the hybrid method has significantly reduced the computation time. Local porosity theory is applied to quantitatively compare the reconstructed 3-D digital cores with the X-ray micro CT 3-D images. The results indicate that the 3-D digital cores reconstructed by the hybrid method have homogeneity and geometric connectivity similar to those of the X-ray micro CT image. The formation factors and permeabilities of the reconstructed 3-D digital cores are estimated using the finite element method （FEM） and lattice Boltzmann method （LBM）, respectively. The simulated results are in good agreement with the experimental measurements. Comparison of the simulation results suggests that the digital cores reconstructed by the hybrid method more closely reflect the true transport properties than the typical SA method alone.

Core 3 O-型糖链参与大肠杆菌对肠上皮细胞黏附和侵袭的影响

目的探讨Core 3 O-型糖链对大肠杆菌黏附和侵袭肠上皮细胞的影响。方法通过慢病毒转染技术,获得β-1,3-N-乙酰氨基葡萄糖转移酶6(β3gnT6)稳定过表达的肠上皮细胞株(β3gnT6/HT-29和β3gnT6/LS174T)及其对照细胞株(Ctr/HT-29和Ctr/LS174T)。上述细胞株与肠致病性大肠杆菌(EPEC)和肠出血性大肠杆菌(EHEC O157∶H7)共培养,采用细菌梯度稀释克隆计数和荧光显微镜直接观察法,计数黏附于细胞表面的细菌数;上述细胞株与侵袭性大肠杆菌(EIEC)共培养2 h,通过庆大霉素杀灭黏附于细胞表面的细菌,再采用细菌梯度稀释克隆计数法,计数侵袭入细胞内细菌数。最后通过测定单层细胞跨膜电阻值(TEER),评价Core 3 O-型糖链对肠上皮细胞屏障功能的影响。结果细菌克隆计数和荧光显微镜直接观察法均显示,黏附于β3gnT6/HT-29和β3gnT6/LS174T细胞株的EPEC和EHEC O157∶H7少于其对照细胞(P<0.01或P<0.05);侵袭入β3gnT6/HT-29和β3gnT6/LS174T细胞株的EIEC高于其对照细胞(P<0.01或P<0.05);在EPEC或EHEC O157∶H7感染条件下,不同时间点上均呈现出β3gnT6/HT-29和β3gnT6/LS174T细胞株的TEER下降值高于其对照细胞(P<0.01或P<0.05)。结论促进肠上皮细胞Core 3 O-型糖链表达将抑制大肠杆菌黏附于肠上皮细胞,同时对大肠杆菌侵袭易感。

Numerical Analysis of Blast Furnace Performance Under Charging Iron-Bearing Burdens With High Reducibility

The reducibility of iron-bearing burdens was emphasized for improving the operation efficiency of blast furnace. The blast furnace operation of charging the burdens with high reducibility has been numerically evaluated using a multi-fluid blast furnace model. The effects of reaction rate constants and diffusion coefficients were investigated separately or simultaneously for clarifying the variations of furnace state. According to the model simulation results, in the upper zone, the indirect reduction of the burdens proceeds at a faster rate and the shaft efficiency is enhanced with the improvement under the conditions of interface reaction and intra-particle diffusion. In the lower zone, direct reduction in molten slag is restrained. As a consequence, CO utilization of top gas is enhanced and the ratio of direct reduction is decreased. It is possible to achieve higher energy efficiency of the blast furnace, and this is represented by the improvement in productivity and the decrease in consumption of reducing agent. The use of high-reducibility burdens contributes to a better performance of blast furnace. More efforts are necessary to develop and apply highreducibility sinter and carbon composite agglomerates for practical application at a blast furnace.

Absorption performance of DMSA modified Fe_3O_4@SiO_2 core/shell magnetic nanocomposite for Pb^(2+) removal

The purpose of this study is to explore the adsorption performance of meso-2,3-dimercaptosuccinic acid(DMSA)modified Fe3O4@SiO2 magnetic nanocomposite(Fe3O4@SiO2@DMSA)for Pb2+ions removal from aqueous solutions.The effects of solution pH,initial concentration of Pb2+ions,contact time,and temperature on the amount of Pb2+adsorbed were investigated.Adsorption isotherms,adsorption kinetics,and thermodynamic analysis were also studied.The results showed that the maximum adsorption capacity of the Fe3O4@SiO2@DMSA composite is 50.5 mg/g at 298 K,which is higher than that of Fe3O4 and Fe3O4@SiO2 magnetic nanoparticles.The adsorption process agreed well with Langmuir adsorption isotherm models and pseudo second-order kinetics.The thermodynamic analysis revealed that the adsorption was spontaneous,endothermic and energetically driven in nature.

INVESTIGATION ON MICROSTRUCTURE AND TRIBOLOGICAL PROPERITIES OF CORED WIRE ARC SPRAYED Al/Al _2 O_3 COATINGS

Cored wires for electric arc spraying of Al/Al 2 O 3 MMC coatings were developed, with Al 2 O 3 powder as the core material and commercial aluminium strip as the retaining sheath. The bond strength, Al 2 O 3 content, microstructure, micro-hardness and wear resistance of coatings produced by arc spraying of the cored wires were experimentally investigated and were compared with those of pure aluminum coating.

Reconstructing the 3D digital core with a fully convolutional neural network

In this paper, the complete process of constructing 3D digital core by fullconvolutional neural network is described carefully. A large number of sandstone computedtomography (CT) images are used as training input for a fully convolutional neural networkmodel. This model is used to reconstruct the three-dimensional (3D) digital core of Bereasandstone based on a small number of CT images. The Hamming distance together with theMinkowski functions for porosity, average volume specifi c surface area, average curvature,and connectivity of both the real core and the digital reconstruction are used to evaluate theaccuracy of the proposed method. The results show that the reconstruction achieved relativeerrors of 6.26%, 1.40%, 6.06%, and 4.91% for the four Minkowski functions and a Hammingdistance of 0.04479. This demonstrates that the proposed method can not only reconstructthe physical properties of real sandstone but can also restore the real characteristics of poredistribution in sandstone, is the ability to which is a new way to characterize the internalmicrostructure of rocks.

Synthesis of magnetic core–shell structure Fe_3O_4@MCM-41 nanoparticle by vesicles in aqueous solutions

In this study, magnetic core–shell structure Fe3O4@MCM-41 nanoparticles were synthesized with vesicles as soft templates. In the preparation, Fe Cl2 and tetraethy orthosilicate(TEOS) were selected as Fe processor and Si precursor, respectively. Stable vesicles first formed in 0.03 mol·L-11:2 mixture of anionic surfactant sodium dodecyl sulfate and cationic surfactant cetyltrimethyl ammonium bromide. Then, TEOS was added in the vesicle aqueous solution, leading to a highly dispersed solution. After high-temperature calcination, Fe3O4@MCM-41 nanoparticles were obtained. Their structure and morphology were characterized by Saturn Digisizer, transmission electron microscope and vibrating sample magneto-meter. The results indicate that the vesicles are spherical and their size could be tuned between 20 and 50 nm. The average grain diameter of synthesize magnetic core–shell Fe3O4@MCM-41 particles is 100–150 nm and most of them are in elliptical shape. The dispersion of magnetic particles is very good and magnetization values are up to 33.44 emu·g-1, which are superior to that of other Fe3O4 materials reported.

Determination of Hydrocortisone in Cosmetics by CdSe/CdS Quantum Dots-Based Fluoroimmunoassay Using Magnetic Fe304/Au Nanoparticles as Solid Carriers

This work demonstrated the feasibility of detecting hydrocortisone in cosmetics using a novel CdSe/CdS quan- tum dots-based competitive fluoroimmunoassay with magnetic core/shell Fe3Oa/Au nanoparticles （MCFN） as solid carriers. Hydrocortisone antigen was labeled with the synthesized core/shell CdSe/CdS quantum dots （QDs） to form the antigen-QDs conjugate. Meanwhile, hydrocortisone antibody was incubated with MCFN and the immobilized antibody was obtained. The immobilized antibody was then mixed sequentially with hydrocortisone and a slightly excess amount of the QDs-labeled hydrocortisone antigen, allowing their competition for binding with the antibody immobilized on MCFN. The bound hydrocortisone and the antigen-QDs conjugates on MCFN were removed subsequently after the mixture was applied to a magnetic force. The analyte concentration was obtained by measuring the fluorescence intensity of the unbound hydrocortisone antigen-QDs conjugates. The proposed method was characterized by simplicity, rapidity, and high sensitivity with a wide linear working range of 0.5 to 15000 pg·mL^-1 and a low detection limit of 0.5 pg.mL^- 1. The proposed method was successfully applied to the determination of hydrocortisone in cosmetics with satisfactory results.

Dynamic response of ultralight all-metallic sandwich panel with 3D tube cellular core to shallow-buried explosives

The underbody of a vehicle system, either military or civil, is typically made of a relatively thin metallic plate, thus vulnerable to mine blast attacks. To improve the blast resistance, a multitude of protective structures have been proposed as attachments to the thin plate. In the present study, a novel ultralight all-metallic sandwich panel with three-dimensional(3D) tube cellular cores mounted to the vehicle underbody was envisioned as such a protective system. A metallic substrate(mimicking vehicle bottom)was placed above the proposed sandwich panel to construct a sandwich-substrate combinative structure. A series of sandwich panels having 3D tube cellular cores were fabricated via argon protected welding and laser welding. Mechanical responses of the combinative structure subjected to the denotation of 6 kg TNT explosives shallow-buried in dry sand were experimentally measured. Full numerical simulations with the method of finite elements(FE) were subsequently carried out to explore the physical mechanisms underlying the observed dynamic performance and quantify the effects of key geometrical parameters and connection conditions of the protective system. The performance of the proposed sandwich panel under shallow-buried explosives was also compared with competing sandwich constructions having equal mass. Finally, a preliminary optimal design of the 3D tube cellular core was carried out.