Capillary Method Research Articles

Amino and ionic liquid modified ZIF-71 embedded mixed matrix membrane for the enhancing the separation of refrigerant R454A

Due to their high global warming potential (GWP), hydrofluorocarbons (HFCs) are included in various regulations as substances to be phased down. Gas separation membrane technology is expected to provide a better choice for refrigerant separation. In this study, a series of metal-organic frameworks (MOFs)/ polydimethylsiloxane (PDMS) mixed matrix membranes (MMMs) were prepared for the separation of the refrigerant blend R454A (GWP = 145), which consists of a near-zeotropic difluoromethane (R32, GWP = 675) and 2,3,3,3-tetrafluoropropene (R1234yf, GWP = 4). ZIF-71-NH2 was prepared for the first time by solvent-assisted ligand exchange (SALE), and then ZIF-71-NH2@ Ionic Liquid (IL) was prepared by embedding [C2mim][BF4] into the pores of ZIF-71-NH2 by capillary action method. The results showed that a hydrogen bonding network was established between the amino group and PDMS, which improved the interfacial compatibility, and reduced the pore size of ZIF-71, which contributed to an excellent gas separation performance of ZIF-71-NH2/PDMS MMMs. Restricting [C2mim][BF4] to the ZIF-71-NH2 pore can further reduce its pore size, and enhance R32/R1234yf separation performance due to the high selective solubility for R32 and R1234yf. The selectivity of 10wt.% ZIF-71-NH2/PDMS MMM is 25.6% over that of 10wt.% ZIF-71/PDMS MMM. The selectivity of ZIF-71-NH2@IL/PDMS MMM is 38.3% higher than that of ZIF-71-NH2/PDMS MMM. The ZIF-71-NH2/PDMS and ZIF-71-NH2@IL/PDMS MMMs exhibited the most excellent R32/R1234yf separation performance compared with the data currently published in the literature. Moreover, both designed MMMs demonstrated excellent resistance to ageing.

Capillary Skimming of Floating Microplastics via a Water-Bridged Ratchet.

Floating microplastics (MPs) have recently become a major concern in marine pollution; however, current filter-based technology is hardly effective for directly removing such MPs from the water surface because of specific mesh size and clogging issues. This paper introduces a new skimming concept for removing floating MPs utilizing capillary force mediated by the elevation of a hydrophilic ratchet at the air-water interface. MPs floating near the ratchet surface are spontaneously forced toward the ratchet with a concave water meniscus, driven by the Cheerios effect. The MPs can then be skimmed and temporarily held by the deforming concave water meniscus as the ratchet rises. Here, it is found that the stability of the water bridge plays a crucial role in skimming success because it provides capillary adhesion between the MP and the ratchet. The proposed capillary skimming method is observed to be effective across nearly all types of floating MPs, ranging in size from 1 to 4 mm, and with densities varying from 0.02 to 0.97 gcm- 3, which is also demonstrated by a prototype of marine robot cleaner.

Single-Cell Lipidomics: An Automated and Accessible Microfluidic Workflow Validated by Capillary Sampling.

We report the first demonstration of a microfluidics-based approach to measure lipids in single living cells using widely available liquid chromatography mass spectrometry (LC-MS) instrumentation. The method enables the rapid sorting of live cells into liquid chambers formed on standard Petri dishes and their subsequent dispensing into vials for analysis using LC-MS. This approach facilitates automated sampling, data acquisition, and analysis and carries the additional advantage of chromatographic separation, aimed at reducing matrix effects present in shotgun lipidomics approaches. We demonstrate that our method detects comparable numbers of features at around 200 lipids in populations of single cells versus established live single-cell capillary sampling methods and with greater throughput, albeit with the loss of spatial resolution. We also show the importance of optimization steps in addressing challenges from lipid contamination, especially in blanks, and demonstrate a 75% increase in the number of lipids identified. This work opens up a novel, accessible, and high-throughput way to obtain single-cell lipid profiles and also serves as an important validation of single-cell lipidomics through the use of different sampling methods.

A comparative study of blood viscometers of 3 different types.

The greater the viscosity of the blood, the more difficult its flow becomes, leading to an increased incidence of diseases caused by blood circulation disorders. These diseases are commonly associated with the cardiovascular and cerebrovascular systems. High blood viscosity is a primary cause of circulatory system diseases. Studies have shown that accurately measuring blood viscosity and applying this data in clinical trials can help prevent circulatory system diseases. Viscosity data can vary depending on the measurement methods used, even when these methods are based on hydrodynamic principles. Despite using approved blood viscometers, the results often differ depending on the type of viscometer used, potentially causing confusion within the medical field. Informing the medical community about these differences and the level of error associated with each measurement method can help reduce this confusion. To our knowledge, the degree of difference in viscosity measurement results due to different measurement methods and the reasons for these differences have not yet been thoroughly explored. In this study, we selected three blood viscosity measurement methods registered with the Ministry of Food and Drug Safety of Korea to analyze the same canine blood. The viscosity measurements were carried out using each device and compared. The parallel plate and scanning capillary methods yielded similar viscosity values, while the cone plate method showed lower viscosity values. The viscosity of blood, as measured by the three viscometers, differed, indicating that more experimental data must be accumulated to evaluate the cause of these differences. In this paper, we identified several causes of inconsistency and suggested measures to avoid this confusion. However, confirming that the test results show systematic differences is expected to assist clinicians who diagnose and prescribe treatments based on blood viscosity results. The findings of this comparative study are anticipated to serve as a starting point for establishing guidelines or standards for blood viscosity measurement methods.

Method of Detecting Liquid Meniscus in Capillary Using Ultraviolet Sensor

The accuracy of determining the physical and chemical properties of a liquid, in particular, assessing the viscosity of the liquid used, is considered an important technical problem in medicine, food, oil, chemical industries, as well as in other areas that determine the quality and safety of human life and activity. For example, assessing the viscosity of the liquid used is a key stage in the design of hydraulic systems. Today, the improvement of methods for determining the viscosity of a liquid is on the path to automation (digitalization) of measurement instruments and methods. In this area, the activities of metrologists and engineers are consistent with the national program «Digital Economy of the Russian Federation» adopted in 2017. The article discusses the capillary method for determining the kinematic viscosity of a liquid as the most accurate of all possible methods at present. The method is based on determining the time of liquid flow between two marks, which are applied to the walls of a glass capillary viscometer forming a measuring tank. One of the main problems of this method is that all stages of measurement are performed by a person, even recording the moment when the liquid meniscus crosses the mark, which is a violation of one of the key principles of process automation – independence of execution, which only implies monitoring the operation of the system. Since ready-made solutions do not fit the laboratory’s measurement tasks, the management decided to develop and conduct a study of an information and measuring system that will carry out the process of detecting the liquid meniscus at the mark level, as well as recalculate the measured time interval into the kinematic viscosity value. The key decision in this development is the choice of a sensor for detecting the liquid meniscus. Based on the literature review, it was decided to use a photoelectric sensor. A study of the transmission spectra of liquids used in this method was conducted to select the wavelength at which the sensor will operate. Thus, a type of photoelectric sensor designed to operate in the UV range has been selected to automate the method of detecting the liquid meniscus when it crosses a mark applied to a capillary tube. The article is addressed to metrologists who perform verification and calibration of glass capillary viscometers, specialists in the field of experimental and theoretical viscometry. The method proposed by the authors can become the basis for further improvement of the method for measuring the kinematic viscosity of a liquid.

A single-pixel and non-redundant branching-based algorithm for nailfold capillary skeleton line extraction.

Static nailfold capillary parameters are important parameters that reflect the health of the human body. Disease onset or progression is often accompanied by changes in the physiological parameters of the nailfold. Hence, the physiological parameters of the nailfold are closely related to the study of disease, with their automated and high-precision measurements playing a crucial role in these studies. Currently, manually measured values of the nailfold's parameters are the gold standard; however, they are time consuming and labor intensive, making the development of automated measurement methods essential. Most automated measurement methods use skeleton lines; however, current skeleton-thinning algorithms have non-single pixels and redundant branches that lead to reduced measurement accuracy. This study proposes a single-pixel and non-redundant branching-based skeleton line extraction algorithm for nailfold capillaries, which is then applied to nailfold static parameter calculations to improve accuracy. The algorithm includes deletion and restoration templates combined with the depth-first search method to obtain single-pixel skeleton lines without redundant branches. These lines are applied to the static nailfold capillary parameter measurement method based on digital image processing to calculate the blood vessel diameter. The results show that the proposed method can obtain the single-pixel skeleton line without the redundant branches that are required for the parameter calculations and improve the accuracy of the nailfold capillary diameter measurement. Experiments showed that the root mean square errors (RMSEs) of the labeled apical diameter, arterial limb diameter, and venous limb diameter were 0.794, 0.756, and 0.830 µm, respectively, when the calculated results were compared with those of the manual calculations. According to the accuracy formula, the accuracy of the method in this study is 90%. We calculated the P values of the algorithmic and manual measurements to P<0.001 and found that the difference in the measurements of the proposed algorithm is statistically significant. Therefore, the method in this study has high sensitivity and specificity for the measurement of normal nailfold capillaries. The proposed algorithm could obtain single-pixel skeleton lines without redundant branches, thereby improving the nailfold static parameter measurement accuracy.

CE-MS and CE-MS/MS for the multiattribute analysis of monoclonal antibody variants at the subunit level

The analysis of product-related substances and impurities is a critical step in the biopharmaceutical quality control of multiattribute monoclonal antibodies (mAbs), as posttranslational modifications or other variants can influence the product's biological activity. Many approaches are available for variant analysis; however, they are either variant-specific, mAb-specific, time-consuming, or require expensive equipment. Here, we present a generic capillary electrophoretic method based on a neutral-coated capillary which was coupled to mass spectrometry (MS) via the nanoCEasy interface for mAb variant analysis at the subunit level (enzymatically digested and reduced mAb). The method enabled the separation of several (i) size variants (e.g. glycosylation variants) and (ii) charge variants (e.g. c-terminal lysin clipping) as well as (iii) multiple other proteoforms (e.g. additional glycation) and (iv) incompletely reduced subunits. Separated variants were confirmed by MS/MS fragmentation even for small mass deviations like deamidation or open disulfide bridges. The system, initially developed for one mAb, was tested with nine other IgG1s to show the general applicability of the system. The presented multiattribute method enables fast and detailed characterization of mAb variants with little sample preparation and relatively simple separation equipment enabling the separation of a large set of mAb variants.

Surface structures and wettability: Their roles in enhancing nucleate boiling heat transfer of refrigerants

Nucleate boiling is an effective heat transfer mechanism. Previous studies have demonstrated that modifying surface structure or wettability can independently improve nucleate boiling efficiency; however, the combined effects and optimal modification sequence remain underexplored. This research aims to comprehensively analyze the influence of surface structure and wettability on the nucleate boiling heat transfer performance of refrigerants. Different surface structures and wettability were prepared using surface polishing, laser ablation, mechanical cutting, and a combination that involved initially employing laser ablation, followed by the application of chemical etching, and finishing with the treatment using materials possessing low surface energy. The static contact angles on these surfaces were measured via the capillary rise method, followed by pool boiling experiments and bubble behavior visualization. The results show that increasing surface wettability can enhance bubble departure frequency and capillary wicking, thereby improving critical heat flux and heat transfer coefficient. The key to optimizing surface modification to enhance critical heat flux involves constructing alternating high and low nucleation core regions to reduce interactions between bubbles; for enhancing heat transfer coefficient, the key lies in constructing compact nanoscale structures that expand the heat transfer and nucleation area, followed by improving wettability.

Possibility of using the imaged capillary isoelectric method as a multi-attribute method for bispecific antibodies.

An imaged capillary isoelectric focusing (icIEF)-based method was developed and validated as a multi-attribute method for a bispecific antibody (BsAb). First, as the traditional application of the icIEF method, it serves as an identity assay and purity assay for the BsAb. Second, the method can also be used as an impurity assay for the homodimer monoclonal antibodies generated during BsAb assembly. The homodimer impurity analysis for BsAb is usually done by hydrophobic interaction chromatography methods in the industry. The icIEF method has good sensitivity (down to 4µg/mL in a limit of quantitation) when UV fluorescence detection is used, which detects the native fluorescence of proteins. This is the first report that an icIEF method has been applied as impurity assay.

Density, thermal expansion, dynamic viscosity of halogenated arenes

Purpose. Experimental study of the density, thermal expansion and dynamic viscosity of halogenated arenes at temperatures from 293.15 to 343.15 K and atmospheric pressure 97.992 kPa.Methods. Density was determined by the pycnometric method, viscosity by the capillary method. A quartz pycnometer type PZh2 with a nominal capacity of 10 ml and a glass capillary viscometer type VPZh-2 with a nominal capillary diameter of 0.34 mm were used. The mass of liquids was measured using an electronic scale VSL-200/0.1A with a division value of 0.0001 g. Numerical methods were used to process the experimental results.Results. Experimental data were obtained on the density, coefficient of volumetric thermal expansion and dynamic viscosity of liquid o-xylene, ethylbenzene, fluorobenzene, chlorobenzene, bromobenzene, toluene, o-fluorotoluene, mfluorotoluene, p-fluorotoluene, o-chlorotoluene, m-chlorotoluene, p-chlorotoluene, 2,4-dichlorotoluene, 2,6-dichlorotoluene. Density and dynamic viscosity data are approximated by a third-degree polynomial. Data on the coefficient of volumetric thermal expansion are obtained from approximated measured density data. The maximum estimate of the measurement error for density was 0.13 %, for dynamic viscosity – 3.5 %. The maximum calculation error for the coefficient of thermal expansion is estimated at 3 %.Conclusion. Mathematical processing of the obtained experimental data on density and dynamic viscosity made it possible to obtain analytical relations in the form of power polynomials that allow calculating the values of these quantities at any temperature from the studied temperature range and atmospheric pressure with an error not exceeding the error of experimental determination. The calculated values are in good agreement with the data provided in the reference and scientific literature. The experimental data obtained complement the information on the properties of some of the liquids under consideration, for which the dependences of density and viscosity on temperature are poorly understood. The substances under study are used in various sectors of the economy and are therefore technically important liquids. The measurement results can be used in condensed matter physics, for the analysis of liquid hydrocarbons, and can be useful in the chemical industry.

Imaged capillary isoelectric focusing method development for charge variants of high DAR ADCs

BackgroundCharge heterogeneity is a critical quality attribute for therapeutic biologics including antibody-drug conjugates (ADCs). Developing an ion exchange chromatography (IEX) or an imaged capillary isoelectric focusing (icIEF) method for ADCs with high drug-to-antibody ratio (DAR) is challenging because of the increased hydrophobicity from the payload-linker, DAR heterogeneity, and payload-linker instability. A sub-optimal method can be poorly stability-indicating due to the inability to discern contributions from charge and size variants conjugated with different number of drugs/payloads. Systematic strategy and guidance on charge variant method development is highly desired for high DAR ADCs with various complex structures. ResultsThis work encompasses the development and optimization of icIEF methods for high DAR ADCs of various DAR values (4–8) and payload linker chemistry. Method optimization focuses on improving resolution and stability indicating capabilities and differentiating contributions from the protein and payload-linker. Types, proportion, and combination of solubilizers and carrier ampholytes, as well as focusing parameters were interrogated. Our findings show that the structural units of the linker, the DAR, and the payload chemistry prescribe the selection of buffer, solubilizer, and ampholyte. We demonstrate that a stronger denaturant or solubilizer is needed for high DAR ADCs with polyethylene glycol (PEG)-containing linker structure compared to peptide linker. For unstable payload-linker, buffer system enhances sample stability which is vital to method robustness. In addition, a longer isoelectric focusing time is necessary for an ADC than its corresponding antibody to reach optimal focusing. SignificanceTo the best of our knowledge, this is the first comprehensive study on icIEF method development for charge variant determination of high DAR ADCs with unique physicochemical properties.

Model Modification of the Soil–Water Characteristic Curve of Unsaturated Weak Expansive Soil

This study evaluates the impact of compaction on the soil–water characteristic curve of unsaturated remodeled weakly expansive soils by assessing changes in soil pore structure resulting from variations in compaction. The remodeled weakly expansive soil in the Xinjiang Hami area is taken as the research subject to investigate how compaction affects microscopic pore structure using mercury intrusion testing. Subsequently, mercury intrusion porosimetry is employed to examine pore structure and distribution patterns at different dry densities. Based on the capillary principle and experimental methods (filter paper method and pressure plate method test), modified soil–water characteristic curves are obtained by fitting them with a three-parameter model law. The results indicate that higher dry density leads to an increased air intake value and significantly reduces the total volume of large pores within samples. Both the Fredlund and Xing model and the three-parameter model effectively capture the influence of initial dry density on the development pattern of the soil–water characteristic curve.

Far-from-equilibrium solid–liquid interfacial properties of aluminum

Simulating quantitatively far-from-equilibrium conditions, which is relevant to a host of rapid solidification processes, has remained a major challenge where theoretical models and physical mechanisms for far-from-equilibrium solid–liquid (SL) interface are essential. Herein, we investigate the effects of far-from-equilibrium state and external strain on SL interfacial properties by using capillary fluctuation method and models based on transition rate theory. Under an extreme temperature gradient (TG), both SL interfacial stiffness (S) and SL interface velocity (v) are found to increase with TG. The nonlinear relationship between v and temperature is revealed over a large undercooling range (640 K). It is found that an external strain (ϵ) of 1%–3% could decrease S by 10%–30%. v is found to increase with external strains at large undercooling. Tensile strains decrease the activation energy (Q) and viscosity, thus facilitating SL interface movement. A strain-dependent Gibbs–Thomson condition is proposed by incorporating linear S-ϵ and Q-ϵ relations. Our systematically theoretical discussion on the far-from-equilibrium SL interfacial properties could provide a predictive guideline on SL interface behavior in the additive or extreme manufacturing.

Blood group distribution and its association with bleeding time and clotting time among medical students

Background: Blood group, bleeding time (BT), and clotting time (CT) are routinely performed tests in the hospital, especially before any surgeries and blood transfusion. Aims and Objectives: The objective of the study is to see if there is any association of blood group with BT and CT and the gender difference in BT and CT. Materials and Methods: A cross-sectional study was conducted among 132 medical students of 1st year in the hematology laboratory of the Department of Physiology in KIST Medical College from June 2022 to September 2022. The blood group was determined by a simple agglutination method. BT was determined by Dukes method whereas CT was determined using capillary tube method. Data were analyzed using SPSS-20 software. The difference in BT and CT among various blood groups was done using the ANOVA test and P≤0.05 was considered significant. Student’s t-test was used to find the association of gender with BT and CT. Results: Both BT and CT were found to be more in males than females. However, the difference was significant only in the mean BT (P=0.05, Table 2). There was no significant difference in the mean BT among various blood groups but CT was found to be significant (P=0.05). Conclusion: Our study showed the tendency of bleeding to be more in blood Group B individuals. Multicentric study including a larger population with plasma level of von Willebrand factor might be helpful to verify findings and identify the risk group.

Simultaneous Determination of Glycerol and Carbohydrates in Sweat by Capillary Electrophoresis with Amperometric Detection

Background: Glycerol, sucrose, lactose, glucose, and fructose are important biomarkers in human sweat because their contents can reflect physiological status and health conditions. It is of high importance to determine them in sweat for health monitoring, disease diagnosis, physical training, etc. Aim: The aim of this work is to develop a method based on capillary electrophoresis and amperometric detection for the simultaneous determination of glycerol and carbohydrates in sweat. Objective: A capillary electrophoretic method based on pipette-tip-based detection electrodes and micro-injectors was developed for the simultaneous determination of glycerol, sucrose, lactose, glucose, and fructose in sweat samples Method: Sweat samples diluted in the background electrolyte of 75 mM NaOH aqueous solution were electrokinetically introduced into a piece of separation capillary via pipette tip-based microinjectors. Glycerol, sucrose, lactose, glucose, and fructose were determined by capillary electrophoresis in combination with a pipette-tip-based copper electrode. Results: At a DC voltage of 12 kV, the capillary electrophoretic separation of the five analytes could be achieved in less than 11 min in a piece of 40 cm long fused silica capillary containing 75 mM NaOH aqueous solution. Linearity was observed between the currents and concentrations, with the limits of detection ranging from 0.21 to 0.72 µM at a detection potential of 0.65 V. Glycerol, sucrose, lactose, glucose, and fructose in sweat samples were positively identified and accurately measured. Conclusion: The method was successfully applied in the simultaneous determination of glycerol and carbohydrates in sweat samples with satisfactory assay results. It will find a wide range of applications in clinical diagnosis, health monitoring, and drug and food analysis.

A New Method for Determination of Rifampicin and Isoniazid Resistance in Mycobacterium tuberculosis complex Isolates: Capillary Tube Method

Tuberculosis continues to be an important public health problem worldwide. Culture methods are still considered the gold standard in the diagnosis of tuberculosis and the determination of drug resistance. The most important limitation of these methods is their long turnaround time. Commercial culture systems developed to shorten the duration are emerging as an economic problem, especially for developing countries. Therefore, cheap, fast, easy to apply and objectively evaluable tests are needed. In this study, in addition to culture-based methods for determining RIF and INH resistance in Mycobacterium tuberculosis complex isolates, it was aimed to develop the capillary tube method to accelerate the evaluation process. The study included 27 RIF-resistant, 36 RIF -sensitive, 30 INH-resistant, and 33 INH-sensitive isolates obtained from the mycobacteriology laboratory culture collection, for which susceptibility testing to firstline drugs were previously performed using the BACTEC MGIT 960 system (BD, USA) and were stored. H37Rv standard strain and an external quality control strain (IDT3) with known RIF and INH resistance were used as quality control isolates in the study. As a new testing method, the capillary tube method for detecting rifampicin and isoniazid resistance was compared to the standard BACTEC MGIT 960 system. In the determination of RIF and INH resistance, the sensitivity of the capillary tube method compared to the reference method was determined as 85% and 80%, respectively; however, the specificity values (25% and 45.5%, respectively) for both drugs were found to be low in the studies. The time to detect resistance with the capillary tube method varied between 4-9 days. Capillary tube method, which was developed especially for the rapid identification and treatment of multidrug-resistant isolates, is promising in that it detects resistant strains in a short time with a relatively high sensitivity, although its specificity is very low. It is thought that it would be beneficial to continue the study with a larger number of samples and even improve the method with studies conducted directly from clinical samples.

Consistency analysis of two fingertip capillary blood sampling methods for complete blood count

This study was performed to analyze fingertip capillary blood sampling in pediatric patients using microcapillary blood collection tubes and microhematocrit tubes and to compare the blood cell analysis results obtained via these two blood collection methods. Finger capillary blood was collected from 110 outpatients using microcapillary blood collection tubes and microhematocrit tubes and complete blood count analysis was performed with a Sysmex XS-900i hematology analyzer and manual microscopy for blood cell morphology. Paired data was evaluated for agreement and bias using the microhematocrit samples as the reference group and the samples from the microcapillary blood collection tubes as the observation group. The two blood collection methods demonstrated good agreement for measuring red blood cell (RBC) parameters (i.e., RBC, Hb, Hct, MCV, MCH and MCHC), wherein the relative bias was > allowable total error (TEa) in 0.91%, 1.82%, 11.82%, 1.82%, 0.91% and 8.18% of the parameter measures, respectively. According to industry requirements, the proportion of samples meeting the acceptable bias level should be > 80%. Additionally, the estimated biases at each medical decision level were within clinically acceptable levels for RBC, Hb, Hct, and MCV. However, the proportion of WBC and PLT counts with relative bias > TEa was 25.45% and 35.45%, respectively. Furthermore, the relative bias of the WBC count at the medical decision level of 0.5 × 109/L and that of the PLT counts at the medical decision levels of 10 × 109/L and 50 × 109/L were clinically significant. Bland–Altman analysis further showed a mean bias of 0.66 × 109/L (95% LoA, − 0.79 to 2.11) for the WBC count and 39 × 109/L (95% LoA, − 46 to 124) for the PLT count from the blood samples collected in the microcapillary blood collection tubes compared with the counts of those collected in the microhematocrit tubes. Neutrophil, monocyte, lymphocyte, eosinophil, and PLT counts increased significantly in the microcapillary blood collection tubes compared with those in the microhematocrit tubes, along with an elevated number of instrument false alarms (P < 0.05). The two capillary blood collection devices exhibit performance differences. Therefore, clinicians should pay attention to the variation in results caused by different blood collection methods.

LIQUID PERMEABILITY OF EUCALYPTUS UROPHYLLA WOOD TREATED WITH DIFFERENT DRYING METHODS

In this study, the influence of three different drying methods on the liquid permeability of sapwood and heartwood of Eucalyptus urophylla was investigated. The liquid permeability of the dried wood was assessed by measuring the maximum amount of dyeing solution uptake using the capillary rise method. Subsequently, the microscopic structure of the dried wood was examined by scanning electron microscopy (SEM). The results indicated that the liquid permeability of sapwood dried by microwave vacuum drying (MVD) and conventional kiln drying (KD) was significantly more effective than that of air drying (AD) treated wood. However, there is no significant difference in the effect of MVD and KD on the liquid permeability of sapwood. The liquid permeability of heartwood treated with MVD is significantly better than that treated with KD and AD, and the effect in the effects of AD and KD on the heartwood is not significant. The increased permeability of Eucalyptus urophylla wood can be attributed to the occurrence of macro-cracking or micro-structural damage in the test specimens, resulting from the dislodgement of perforated plates within the wood cells, the rupture of the intercellular layer between vessel and axial parenchyma cells, as well as the rupture of the pit membrane in cross-field pits due to microwave vacuum drying and conventional kiln drying.

Effect of Anionic Surfactants on the Oil-Water-Rock Interactions by an Improved Washburn Method.

The complex and variable structure of subsurface oil reservoirs as well as the small pore throat size of reservoirs make it extremely important to investigate the effect of oil-water-rock interactions for enhancing oil recovery. In this paper, the powder wettability of oil sand with different polar solvents was investigated using the improved Washburn capillary rise method, and the surface free energy of oil sand was calculated in combination with the OWRK method. In addition, the wettability of anionic surfactants HABS and PS solutions on the surface of oil sand was determined, and it showed that their wetting rates showed different trends after CMC (critical micelle concentration). The C×cosθ value of HABS decreased significantly with increasing concentration, whereas PS showed little changes. This may be related to the aggregate structure formed by HABS on the oil sand surface. Meanwhile, the interfacial free energy between crude oil and oil sand was obtained by crude oil-to-oil sand wetting experiments, and found that the wetting rate of crude oil to oil sand was much lower than that of solvents and surfactants. In combination with the above results and the oil-water interfacial tension (IFT), the oil-water-rock three-phase contact angle and the work of adhesion between the crude oil and the solid were obtained by Young's equation. From the three-phase contact angle results, it can be found that the contact angle values of both HABS and PS are obviously higher than that of the simulated water, and both HABS and PS have the ability to significantly reduce the work of adhesion, which shows a strong ability to strip the oil film on the surface of the solid. The research results of this paper are helpful to understand the oil displacement mechanism of chemical flooding in reservoir pores, which is of great significance for improving oil recovery.

Surface tension measurement and molecular simulation for new low global warming potential refrigerants R1132(E) and R1132a

This study performed surface tension measurements assisted by molecular simulations for new candidate refrigerants R1132(E) and its isomer R1132a, which exhibit extremely low global warming potentials. Because the measured saturation density required for the surface tension measurement by the differential capillary rise method is insufficient at low temperatures, the density data was extrapolated by molecular simulations. In the process, quantum chemical and molecular dynamics simulations were performed to reproduce the vapor–liquid equilibrium state, and the accuracy of the obtained molecular force fields was verified by comparing them with the measured data. Based on the obtained surface tension data, validated temperature correlation equations were proposed for R1132(E) and R1132a, respectively, validated in the temperature range from 209 K to 225 K. Furthermore, their parachors, which relate surface tension to saturation density, were determined from the above data as 116.1 and 116.7 for R1132(E) and R1132a, respectively.