Determination of dynamic capillary effect on two-phase flow in porous media: A perspective from various methods

The relationship between capillary pressure and saturation plays a critical role in the characterization of two-phase flow and transport in aquifers and oil reservoirs. This relationship is usually determined under the static condition, where capillary pressure is the only function of saturation. However,considerable experiments have suggested that the dependence of capillary pressure on desaturation rate is under the dynamic condition. Thus, a more general description of capillary pressure that includes dynamic capillary effect has been approved widely. A comprehensive understanding of the dynamic capillary effect is needed for the investigation of the two-phase flow in porous media by various methods. In general, dynamic capillary effect in porous media can be studied through the laboratory experiment, pore-to macro-scale modeling, and artificial neural network. Here, main principle and research procedures of each method are reviewed in detail. Then, research progress, disadvantages and advantages are discussed, respectively. In addition, upscaling study from pore-to macro-scale are introduced, which explains the difference between laboratory experiment and pore-scale modeling. At last, several future perspectives and recommendations for optimal solution of dynamic capillary effect are presented.

Measurement of inner surface roughness of capillary by an x-ray reflectivity method

The inner surface roughness of a capillary is investigated by the reflectivity of x-rays penetrating through the capillary. The results are consistent with the data from atomic force microscope （AFM）. The roughness measured by this new method can reach the order of angstroms with high quality capillaries.

A NOVEL METHOD OF SOLVING THE EXACT EQUATIONS FOR CAPILLARY-GRAVITY WAVES

A new method is presented for the computation of two-dimensional periodic progressive surface waves propagating under the combined influence of gravity and surface tension. The nonlinear surface is expressed by Fourier series with finite number of terms, after the computational domain is transformed into a unit circle. The dynamic boundary equation is used in its exact nonlinear form and the coefficients of Fourier series are found by the Newton-Raphson method successively. This is a neat method, Yielding high prescision with little computational effort.

An integral method for calculation of capillary pressure based on centrifuge data of tight sandstone

The traditional Hassler-Brunner(HB)interpretation method of centrifuge capillary pressure is widely used in materials,soil,biotechnology,and especially in the petroleum industry.However,the assumptions of the traditional method cannot be simultaneously satisfied,the traditional method has been known to lead significant errors in some cases.In this paper,a new double integral method is proposed to evaluate the centrifuge capillary pressure of long tight sandstone samples.Both the changes of capillary length and interface of wetting phase and non-wetting phase fluids are considered by the new integral method,thus the average pressure and saturation derived from the proposed double integral method is more sufficient in theoretic foundation and clearer on physical meaning.By comparing with the measured capillary pressure of long tight sandstone core samples from porous plate,the capillary pressure calculated from traditional HB method is obviously smaller than the measured value,and the discrepancy increases with the decreasing core porosity.However,the average capillary pressure obtained by the proposed double integral method is remarkably consistent with the measured value.The findings of this study can help for better understanding of distribution of wetting phase fluid and average centrifuge capillary pressure in the core during centrifugal process.

In situ synthesis of a spherical covalent organic framework as a stationary phase for capillary electrochromatography

Covalent organic frameworks(COFs)are a novel type of crystalline porous organic polymer materials recently developed.It has several advantages in chromatographic separation field,such as high thermal stability,porosity,structural regularity,and large specific surface area.Here,a novel spherical COF 1,3,5-tris(4-aminophenyl)benzene(TAPB)and 2,5-bis(2-propyn-1-yloxy)-1,4-benzenedicarboxaldehyde(BPTA)was developed as an electrochromatographic stationary phase for capillary electrochromatography separation.The COF TAPB-BPTA modified capillary column was fabricated via a facile in situ growth method at room temperature.The characterization results of scanning electron microscopy(SEM),Fourier transform infrared(FT-IR)spectroscopy,and X-ray diffraction(XRD)confirmed that COF TAPB-BPTA were successfully modified onto the capillary inner surface.The electrochromatography separation performance of the COF TAPB-BPTA modified capillary was investigated.The prepared column demonstrated outstanding separation performance toward alkylbenzenes,phenols,and chlorobenzenes compounds.Furthermore,the baseline separations of non-steroidal anti-inflammatory drugs(NSAIDs)and parabens with good efficiency and high resolution were achieved.Also,the prepared column possessed satisfactory precision of the intra-day runs(n=5),inter-day runs(n=3),and parallel columns(n=3),and the relative standard deviations(RSDs)of the retention times of tested alkylbenzenes were all less than 2.58%.Thus,this new COF-based stationary phase shows tremendous application potential in chromatographic separation field.

Comprehensive tests on rising height of capillary water for coarse grained soil

According to the comprehensive tests on the rising height of capillary water for seven kinds of differ- ent coarse grained soil by use of the method of standpipe, the relationship between the rising height of capillary water and time was obtained, and the influencing factors and rules were analyzed. The data of the steady rising height of capillary water were obtained, and the regression equation of coarse grained soil on steady height and physical indexes （effective grain dl0 and porosity n） was found. Compared with Hazen＇s and other expressions that could estimate the steady height of capillary water of coarse grained soil, the proposed method is satisfactory and the defects of the latter were pointed out.

Nonlinear Capillary-Gravity Waves Produced by a Vertically Oscillating Plate

The nonlinear capillary-gravity wave produced by a vertically oscillating plate, in which the contact-angle model is considered, is studied by use of the Boundary Integral Equation Method (BIEM). The present numerical experiment shows that the code is robust and efficient for modeling the generation and propagation of capillary-gravity waves. It is found that the wave heights of stationary periodic nonlinear waves radiated away from the plate are dependent on the parameters involved in the contact-angle model. The effect of the contact-angle hysteresis and the nonlinearity of capillary-gravity waves on the wave profile is discussed in the paper.

Research on 2D Model of Capillary Discharge Plasma

The physical process of capillary discharge in a PE tube utilized in electro-thermal-chemical(ETC)guns was investigated.ETC guns can enhance the ignition and combustion of propellant in order to reduce the ignition delay and increase muzzle velocity of the projectile.A key component in ETC gun is the capillary plasma source.In this paper,a 2D steady state model of discharge was built by using magnetic hydrodynamics method.It took the plasma energy balance,material ablation,mass and momentum conservations in a quasi-neutral plasma region into account.Also,the effect of different compositions and PE concentration distribution were considered.In order to evaluate the validation of this model,the simulation results are compared with former works.

Effects of Curing Methods on the Permeability and Mechanism of Cover Concrete

Curing methods are one of the most important factors in determining the quality and compactness of cover concrete.The effect of curing methods on the water absorption and sorptivity coefficient of cover concrete with the substitution ratio of fly ash(FA)and ground granulated blast slag(GGBS)for cement between 30 wt%and 40 wt%was studied by capillary water absorption test.The vacuum saturation test and mercury intrusion test were employed to characterize these differences in the pore structure of cover concrete under different curing methods.With further analysis of the compactness of microstructure by SEM,the mechanism of the impact of curing methods on the permeability of cover concrete was revealed.The results obtained indicate that the effect of curing methods on the water absorption,sorptivity coefficient and porosity of cover concrete shows the trend of natural curing>cover curing>water curing>standard curing.It is also shown that reasonable curing is advantageous to reduce the porosity and permeability of cover concrete.In natural curing conditions,the appearance of porosity increasing and pore structure coarsening is more critical for covering concrete with mineral admixtures than for pure cement concrete.Therefore,the permeability of cover concrete with mineral admixtures is more sensitive to the early-age curing methods.

基于孔隙分形特征的水泥基毛细吸力预测模型

为深入理解水泥基毛细吸力与含水量的关系,采用分形几何学方法和毛细管理论提出了考虑孔隙分形特征的水泥基毛细吸力预测模型。该模型通过建立分形模型参数与试样配合比的拟合关系,实现了不同配合比水泥基毛细吸力的快速预测。基于相对湿度法开展了水泥基孔径分布测量验证试验,结果表明:不同配合比(水、灰、砂)水泥基试样孔隙均具有明显分形特性,可用Menger海绵体分形模型较好描述;毛细吸力模型预测结果与验证试验测试结果的偏差主要集中在±20%以内,模型可以较为准确地预测水泥基毛细吸力与含水量的关系。

盐酸艾司洛尔残留溶剂测定方法优化

目的:优化盐酸艾司洛尔残留溶剂检测方法,以便于内部质量控制。方法:使用气相色谱顶空进样方式,选择合适的顶空平衡温度和时间,降低样品对仪器的污染,优化溶剂比例,降低基质效应,调整了载气流速和分流比,采用极性毛细管柱程序升温的方法,延长了高温段保持时间等,并进行方法学验证。结果:乙醚、乙酸乙酯、甲醇、甲苯均能得到有效分离,精密度良好,峰面积和质量浓度均呈很好的线性关系,分别考察样品加标50%、100%、150%3个浓度的准确度,平均回收率均能在94.8%~105.6%。结论:该方法准确,灵敏度高,克服了《中国药典》方法的缺陷,可用于盐酸艾司洛尔残留溶剂检测。

毛细管顶空气相色谱法高灵敏监测花生大豆根瘤生物固氮能力

建立了测定花生和大豆根瘤菌生物固氮能力的毛细管顶空气相色谱法,利用固氮酶还原乙炔气体为乙烯的经典方法,实现了高浓度乙炔中痕量乙烯的高灵敏分析。利用顶空进样方式,分离柱采用HP-PLOT Q毛细管色谱柱,程序升温,采用氢离子化检测器,对乙烯标准气体进行了定量分析。乙烯检测范围宽为0.125~30000μmol/mol,相关系数为0.9996,检测限(LOD)为0.0341μmol/mol,检出限优于已有报道。该方法检测精密度好,5次检测的相对标准偏差为2.32%。乙烯样品的回收率为95.8%~110%,相对标准偏差为1.54%~3.47%。同时,对乙烯和实际样品进行检测时,与GDX-502填充柱的传统气相色谱法的测定结果一致,表明所建立的乙烯顶空气相色谱法具有较高的可靠性。此外,该方法分析时间缩短至3 min,利用自动进样方式,检测通量大,适用于花生和大豆根瘤菌中固氮能力的快速准确测定,能满足花生和大豆生物固氮研究中乙炔还原法测定乙烯的需求。

考虑膜态水渗流的非饱和土渗透系数计算方法研究

当前采用土-水特征曲线计算非饱和土渗透系数的方法主要分为经验模型和统计模型两大类。经验模型的计算结果取决于模型中的经验系数,统计模型基于毛细模型采用统计学相关理论推导得出,因此统计模型计算结果相对可靠。研究发现,统计模型主要研究毛细水迁移规律,并未考虑土体中的结合水。因物理化学作用,部分土颗粒表面会吸附水膜,该水膜可作为液态水分的传输媒介。水膜厚度主要取决于土颗粒表面与土中水的相互作用,水膜厚度决定了土颗粒表面膜态水的迁移速率。首先计算单个颗粒表层吸附水膜的厚度、膜态水迁移速率;其次考虑土体中不同粒径颗粒的随机接触,利用级配曲线计算不同粒径颗粒的连接概率;最终依据单颗粒膜态水的迁移速率并结合颗粒间的随机接触概率,提出非饱和土膜态水的渗透系数预测模型。为验证模型的可靠性,选取其他文献中的试验数据对比模型预测结果,对比结果表明本文预测结果与文献试验结果吻合度较好,比传统统计模型表现出一定的优越性。

单抗药物还原毛细管电泳法方法学验证研究

目的对还原十二烷基硫酸钠毛细管电泳法(reduced capillary electrophoresis-sodium dodecyl sulfate,rCE-SDS)用于单抗药物的纯度检测进行方法学验证,为业界此类质量控制方法的方法学验证提供参考。方法按照2020版《中华人民共和国药典》通则<3127>的方法检测样品,对该方法的专属性、线性、准确度、精密度、范围、定量限、耐用性进行验证。结果本方法专属性较好;线性拟合结果良好(均R^(2)>0.99)。各分析用样品主峰的准确性结果满足98%~102%,总杂质和非糖基化重链(non-glycosylated heavy chain,NGHC)的准确性结果均满足70%~130%;重复性和中间精密度的RSD均≤15%;主峰的范围为≥92.4%,总杂质范围为0.36%~7.6%,NGHC的范围为0.12%~3.8%;总杂质和NGHC的定量限分别为0.36%和0.12%。结论本方法验证各项指标均符合预设可接受标准,且该研究可以为此类方法学验证的科学性和合理性设计提供参考。

渗透结晶型防水材料活性母料制备与优化试验

水泥基渗透结晶型防水材料(cementitious capillary crystalline waterproofing,CCCW)主要通过活性化学物质的渗透结晶反应产生作用。为深入研究CCCW活性材料的制备与应用性能,选用羟基乙叉二膦酸(hydroxyethylidene diphosphonic acid,HEDP)络合剂、硅酸钠沉淀剂、氢氧化钙以及纳米二氧化硅(nano-silica,NS)组成活性母料,采用四因素四水平的正交试验设计,通过显著性分析确定对混凝土抗压强度、耐水性和抗硫酸盐侵蚀性能的主要影响因素,并由综合功效系数结合抗硫酸盐侵蚀系数研究了活性母料的最优组分配比,同时采用扫描电镜和X射线衍射(X-ray diffraction,XRD)分析其微观作用机理。结果表明,硅酸钠能影响水泥水化进程且过量使用会使得内部结构松散,对混凝土抗压强度影响最显著;HEDP、硅酸钠、氢氧化钙以及NS的最佳掺量分别为水泥质量的0.15%、1%、1%、3%;活性母料能有效改变钙矾石形貌,使得结构密实度增加。研究结果可为CCCW的改进与应用提供重要技术参考。

二冬二母二草汤的化痰作用研究

目的研究二冬二母二草汤的化痰作用。方法选择50只KM小鼠,以10只为1组,随机分成5组,根据其给药不同将组名命名为空白对照组(蒸馏水);盐酸溴己新组(9.6 mg/kg);二冬二母二草汤组高剂量组(18.6 g生药/kg)、中剂量组(9.3 g生药/kg)、低剂量组(4.65 g生药/kg),分析二冬二母二草汤对小鼠气管酚红排泌的影响。选择50只英国种豚大鼠,以10只为1组,随机分成5组,根据其给药不同将组名命名为空白对照组(蒸馏水);盐酸溴己新组(5.6 mg/kg);二冬二母二草汤组高剂量组(18.6 g生药/kg)、中剂量组(9.3 g生药/kg)、低剂量组(4.65 g生药/kg),分析二冬二母二草汤对大鼠痰液的影响。结果KM小鼠实验中,二冬二母二草汤中剂量组、低剂量组和盐酸溴己新组的小鼠酚红浓度分别为(0.88±0.17)、(1.21±0.18)、(0.91±0.31)μg/ml,对比空白对照组的(0.71±0.16)μg/ml显著升高,差异具有统计学意义(P<0.05或<0.01或<0.001)。英国种豚大鼠实验中,二冬二母二草汤高剂量组、中剂量组、低剂量组和盐酸溴己新组的痰液长度分别为(13.95±6.05)、(19.61±7.83)、(17.02±5.20)、(16.12±5.03)cm,对比空白对照组的(7.09±2.87)cm显著延长,差异具有统计学意义(P<0.05或<0.01或<0.001)。结论二冬二母二草汤的化痰效果显著,可广泛用于治疗肺阴亏虚型咳嗽。

毛细管熔点测定仪比对样品的测量不确定度评定与分析

本文依据JJG 701—2008《熔点测定仪》国家计量检定规程和JJF 1059.1—2012《测量不确定度评定与表示》国家计量技术规范,根据2021年全国毛细管熔点测定仪检定装置计量比对具体方案要求(项目编号2021-B-13),对毛细管熔点测定仪比对样品测量不确定度进行评定与分析。

封闭负压引流技术对创周组织水肿及血管通透性的影响

目的创面封闭负压引流技术促进创面愈合的机制尚未清楚,探讨封闭负压引流对创周组织水肿及血管通透性的影响。方法以兔耳背全层皮肤缺损的急性创面为模型,右耳用创面多孔闭合敷料,并给予负压引流,为治疗组;左耳创面不作封闭负压引流,其余处理同治疗组,为对照组。在治疗后第2,4,6,8天分别利用干湿法检测对照组和治疗组创周组织的含水量,同时用伊文氏蓝渗出法检测创周组织的血管通透性。结果封闭负压引流组创周组织含水量在2,4,6,8d均低于对照组(P<0.05);伊文氏蓝含量在第2天两组差异无显著性意义(P>0.05),但在4,6,8d明显低于对照组(P<0.01)。结论封闭负压引流治疗可以有效的减轻创周水肿、降低血管通透性。

高效毛细管电泳

从基本原理、影响因素、分类及其特点、检测方法及在无机、有机、生物和医药方面的应用等方面,评述了高效毛细管电泳的基本问题及发展现状。共引用文献84篇。

Wavefield simulation in porous media saturated with two immiscible fluids

Wavefields in porous media saturated by two immiscible fluids are simulated in this paper.Based on the sealed system theory,the medium model considers both the relative motion between the fluids and the solid skeleton and the relaxation mechanisms of porosity and saturation（capillary pressure）.So it accurately simulates the numerical attenuation property of the wavefields and is much closer to actual earth media in exploration than the equivalent liquid model and the unsaturated porous medium model on the basis of open system theory.The velocity and attenuation for different wave modes in this medium have been discussed in previous literature but studies of the complete wave-field have not been reported.In our work,wave equations with the relaxation mechanisms of capillary pressure and the porosity are derived.Furthermore,the wavefield and its characteristics are studied using the numerical finite element method.The results show that the slow P3-wave in the non-wetting phase can be observed clearly in the seismic band.The relaxation of capillary pressure and the porosity greatly affect the displacement of the non-wetting phase.More specifically,the displacement decreases with increasing relaxation coefficient.