盐岩渗透特性的试验研究及其在深部储气库中的应用

为给深部盐岩地层(≥1 500 m)中所建天然气储库的稳定性和密闭性评价提供科学指导,针对取自江苏金坛的不同杂质含量盐岩试样,在荷兰乌德勒支大学HPT实验室开展了在三轴压缩条件下的瞬态法渗透率测试研究,揭示盐岩的变形特征与渗透率演化规律.试验研究表明:在围压20 MPa的常温测试条件下,随着偏应力从0～40MPa递增,损伤后的低含泥盐岩的渗透率从10-16 m2逐渐下降至10-21 m2以下,而损伤后的高含泥盐岩的渗透率则平均高出前者1～2个量级,推测表明损伤后的盐岩在加载下裂纹闭合、孔隙减小、逐渐压缩密实,进而渗透率快速降低,同时也表明外载压密作用对纯盐岩的裂纹压缩闭合、甚至损伤修复作用更显著.根据试验成果,并利用H.Alkan等[11]建立的盐岩压缩-扩容边界线对位于1 500～2 000 m深部的盐岩地层中的球形腔体的围岩应力状态分析显示,围岩几乎都位于扩容边界以下的安全区域,由此推知:即使在储气库低压运行条件下,围岩中较难发生扩容而导致密闭性失效事件发生,腔体的密闭性能极好.该研究为深部盐穴储气库的可行性和密闭性评价提供有利支撑.     

Dimensional anisotropy in 18 pct Ni maraging steel

Annealing after hot rolling or extrusion produces anisotropic shape changes in 18 pct Ni maraging steel. It has been observed that the material contracts along the longitudinal direction but expands perpendicular to it. This peculiar behavior has been studied in situ by means of a dilatometer. The dimensional anisotropy (DA) was found to decrease with an increase in the annealing temperature. The metallographic investigations have led to the conclusion that DA is related to the presence of banding in the material.     

Enhancing Lipase Biosynthesis by Aspergillus Melleus and its Biocatalytic Potential for Degradation of Polyester Vylon-200

Catalysis Letters - Herein, response surface methodology (RSM) was employed to optimize the bioprocess parameters for improved production of extracellular lipase by Aspergillus melleus and...     

Factors Affecting Retailer’s Adopti on of Mobile Payment Systems: A SEM-Neural Network Modeling Approach

Wireless Personal Communications - The development of mobile commerce depends on extensively accepted mobile payment (MP) systems. Even though new MP methods have been gradually induced in the...     

MDVA-GAN: multi-domain visual attribution generative adversarial networks

Neural Computing and Applications - Some pixels of an input image have thick information and give insights about a particular category during classification decisions. Visualization of these pixels...     

Solid State Fluorination on the Minute Scale: Synthesis of WO3−xFx with Photocatalytic Activity

Solid state reactions are notoriously slow, because the rate‐limiting step is diffusion of atoms or ions through reactant, intermediate, and product crystalline phases. This requires days or even weeks of high temperature treatment, consuming large amounts of energy. Metal oxides are particularly difficult to react, because they have high melting points. The study reports a high‐speed solid state fluorination of WO₃ with Teflon to the oxyfluorides WO_3–xFx on a minute (<10 min) scale by spark plasma sintering, a technique that is used typically for a high‐speed consolidation of powders. Automated electron diffraction analysis reveals an orthorhombic ReO₃‐type structure of WO_3–xFx with F atom disorder as demonstrated by ¹⁹F magic angle spinning nuclear magnetic resonance spectroscopy. The potential of this new approach is demonstrated by the following results. i) Mixed‐ valent tungsten oxide fluorides WO_3–xFx with high F content (0 < x < 0.65) are obtained as metastable products in copious amounts within minutes. ii) The spark plasma sintering technique yields WO_3–xFx nanoparticles with high photocatalytic activity, whereas the corresponding bulk phases obtained by conventional solid‐state (ampoule) reactions have no photocatalytic activity. iii) The catalytic activity is caused by the microstructure originating from the processing by spark plasma sintering.     

Osmotic stress on nitrification in an airlift bioreactor

The effect of osmotic pressure on nitrification was studied in a lab-scale internal-loop airlift-nitrifying reactor. The reactor slowly adapted to the escalating osmotic pressure during 270 days operation. The conditions were reversed to the initial stage upon full inhibition of the process. Keeping influent ammonium concentration constant at 420 mg N L(-1) and hydraulic retention time at 20.7h, with gradual increase in osmotic pressure from 4.3 to 18.8x10(5) Pa by adding sodium sulphate, the ammonium removal efficiencies of the nitrifying bioreactor were maintained at 93-100%. Further increase in osmotic pressure up to 19.2x10(5) Pa resulted in drop of the ammonium conversion to 69.2%. The osmotic pressure caused abrupt inhibition of nitrification without any alarm and the critical osmotic pressure value causing inhibition remained between 18.8 and 19.2x10(5) Pa. Nitrite oxidizers were found more sensitive to osmotic stress as compared with ammonia oxidizers, leading to nitrite accumulation up to 61.7% in the reactor. The performance of bioreactor recovered gradually upon lowering the osmotic pressure. Scanning and transmission electron microscopy indicated that osmotic stress resulted in simplification of the nitrifying bacterial populations in the activated sludge as the cellular size reduced; the inner membrane became thinner and some unknown inclusions appeared within the cells. The microbial morphology and cellular structure restored upon relieving the osmotic pressure. Addition of potassium relieved the effect of osmotic pressure upon nitrification. Results demonstrate that the nitrifying reactor possesses the potential to treat ammonium-rich brines after acclimatization.     

Raman spectroscopy and AC conductivity of polyaniline montmorillonite (PANI–MMT) nanocomposites

A series of polyaniline/montmorillonite clay (PANI–MMT) nanocomposites were synthesised by in situ polymerisation of aniline in acidic medium in the presence of varying amounts (from 1 to 30 wt%) of MMT and a substoichiometric amount of ammonium persulfate (APS). For a preferred molar ratio of monomer to oxidant of 2:1, the aniline was polymerised and largely incorporated into the MMT. The PANI–MMT nanocomposites were characterised and compared by wide-angle powder X-ray diffraction and UV–Vis spectroscopy. Raman spectroscopy was used to investigate the interaction between clay layers and the intercalated polymer chains. Room temperature AC conductivity was measured in the frequency range 30 Hz to 1 MHz. Pure PANI and all the composites exhibited a low frequency region of frequency independent AC conductivity followed by a high frequency dispersive region where the AC conductivity obeyed a fractional power law of frequency dependence. The fractional exponent n for all the nanocomposites is significantly high as compared to that of pure PANI; n = 0.9 for all the composites whereas for pure PANI n = 0.2. In pristine PANI the onset of the dispersive region ω _c is at a much higher frequency (at 300 kHz) as compared to the nanocomposites in which ω _c is about 10 kHz.     

Synthesis and Characterization of Cellulose α-Lipoates: A Novel Material for Adsorption onto Gold

Summary Novel α-lipoic acid esters of cellulose (cellulose α-lipoates) were synthesized homogeneously in N,N-dimethylacetamide (DMAc)/LiCl using different methods for the in situ activation of the carboxylic acid. Thus, cellulose α-lipoates with degrees of substitution (DS) in the range 0.11 to 1.45 were accessible with N,N’-carbonyldiimidazole and p-toluenesulphonyl chloride as in situ activating agents for the α-lipoic acid. The reactions proceeded totally homogeneous with high yields giving cellulose α-lipoates soluble in DMSO. The α-lipoate moiety containing a S-S function stays intact during the reaction as revealed by FTIR and ¹H NMR spectroscopy. The cellulose α-lipoates showed self-assembly onto gold surface yielding layers with a thickness of 2.9–4.9 nm, which can be confirmed by surface plasmon resonance. The perpropionylated cellulose α-lipoates form films with a comparably low thickness of 0.9 nm.