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The article discusses a new suture method called the multi-gradient buried vertical mattress suture, which is used to close high-tension wounds. The method involves three buried vertical mattress sutures and an intradermal suture to reduce tension on wound edges and scar hyperplasia. However, the method does have the drawback of increased skin pigmentation and scarring at puncture points. The article provides a detailed description of the operative procedure and presents a typical case study to demonstrate the effectiveness of the suture method in reducing skin tension and improving aesthetic outcomes. [Extracted from the article]

To ensure the safe and economic operation of a waxy crude oil production process, the microdynamic mechanism and thermodynamic characteristics of the wax gelation process need to be revealed at nanoscale. The molecular dynamics model was established to characterize the phase transition and gelation behavior of waxy molecules in a multiphase system (including oil, asphaltene and water). The relative error between the simulated results and experimental data measured by Dutour et al. (2002) was less than 5%. Under the coupling effect of different operation parameters, the molecular dynamics simulation was employed. The simulated results showed that the spherical paraffin crystals underwent the processes of dissolution, diffusion and aggregation. After which waxy cluster crystals with larger amount but smaller volume were formed, which would be deposited on the inner wall under the concentration gradient. The influence mechanisms of different operating parameters on wax gelation were analyzed. And it was found that the increase in temperature and water cut decrease the wax precipitation, while the increase in pressure enhance the wax precipitation rate. Furthermore, by means of hydrogen bonding and the effect of similar dissolution, water and asphaltene molecules also affect the wax precipitation process at the molecular scale. The investigations in this study provide theoretical support for the paraffin removal and control in a waxy crude oil production system. The molecular dynamics model and details. Image 1 • The MD model for characterizing the phase transition and gelation behavior of waxy molecules is established. • The microscopic mechanism of dissolution, diffusion and aggregation process of waxy crystals is revealed. • The influence mechanism of different operation parameters on phase transition and gelation process is studied. • We have confirmed that the hydrogen bond with the structure of C − H ⋯ O will form between water and waxy molecules. [ABSTRACT FROM AUTHOR]

To explore the influence of different wax components and the shear effect exerted by the pump and pipe wall in the process of crude oil pipeline transportation on the microbehavior of wax aggregation in crude oil at low temperatures, molecular dynamics models of binary and multivariate systems of crude oil with different wax components are established in this paper. The simulation results are compared with the existing experimental results and the NIST database to verify the rationality and accuracy of the models. By using the established binary model to simulate four crude oil systems containing different wax components, it can be found that the longer the wax molecular chain, the more easily the wax molecules aggregate. The influence of temperature on the aggregation process of wax molecules with different chain lengths is also studied. The lower the temperature, the greater the difference in wax molecular aggregation degree caused by the difference in molecular chain length. Nonequilibrium molecular dynamics is used to simulate the shear process of a multivariate system of crude oil, and the micromechanisms of the shear effect on the aggregation process of wax molecules are studied. Shearing can destroy the stable structure of crude oil, resulting in the orientation and conformational transformation of wax molecules, and obtaining the region of wax molecules sensitive to temperature and shear effects, the temperatures of which are below the wax precipitation point and the shear rate of which is lower than the maximum shear rate to prevent the molecular structure from being destroyed. At the same time, the sensitivity of wax components with different chain lengths to the shear effect is studied. The research results provide theoretical guidance for ensuring the safe and economic operation of waxy crude oil production. [ABSTRACT FROM AUTHOR]

Abstract Energy consumption plays a dominant role in the technical and economic indicators of pipeline operation, and is greatly influenced by operation schemes. However, the conventional energy consumption model is often analyzed from the perspective of "energy" in the process of optimization without addressing the issue of energy quality. Based on energy quality, this paper analyzes exergy loss and exergy efficiency of every component of the crude oil pipeline transportation system. The expression of the exergy loss is determined and the mathematical model of the pipeline transportation system is established with the optimization objective of minimizing the total exergy loss of the system, which is combined the two optimization algorithms of genetic algorithm and multi-objective programming. Using one external oil pipeline in northeast China as an example, the model is used to do hierarchical optimization for the equipment arrangement and operation parameters of each station in the pipeline transportation system. The results found that the total oil transportation cost and the total exergy loss of the pipeline transportation system after optimization have seen an obvious improvement in the effective utilization of energy when compared to pre-optimized levels. The purpose of reducing the operation energy consumption and exergy loss of the system as well as each subsystem simultaneously has been achieved, and the theoretical basis is provided for the energy consumption optimization of oil pipeline transportation system operations. [ABSTRACT FROM AUTHOR]

Background: Stroke represents the second most prevalent contributor to global mortality. The Chinese Visceral Adiposity Index (CVAI) serves as an established metric for assessing visceral adiposity in the Chinese population, exhibiting prognostic capabilities. This investigation aimed to explore the association of CVAI and new-onset stroke among middle-aged and older Chinese populations. Methods: The study employed data from the 2011 and 2018 China Health and Retirement Longitudinal Study (CHARLS) to assess the association of CVAI and the incidence of new-onset stroke. Utilizing a directed acyclic graph (DAG), 10 potential confounders were identified. Moreover, to explore the association between CVAI and new-onset stroke, three multifactor logistic regression models were constructed, accounting for the identified confounders and mitigating their influence on the findings. Results: The study comprised 7070 participants, among whom 417 (5.9%) experienced new-onset strokes. After controlling for confounding variables, regression analysis suggested that the new-onset stroke's highest risk was linked to the fourth quartile (Q4) of the CVAI, with an odds ratio (OR) of 2.33 and a 95% confidence interval (CI) of 1.67–3.28. The decision tree analysis demonstrated a heightened probability of new-onset stroke among hypertensive individuals with a CVAI equal to or greater than 83, coupled with a C-reactive protein level no less than 1.1 mg/l. Age seemed to have a moderating influence on the CVAI and new-onset stroke association, exhibiting a more prominent interaction effect in participants under 60 years. Conclusions: In middle-aged and older Chinese populations, a linear relationship was discerned between CVAI and the probability of new-onset stroke. CVAI provides a predictive framework for stroke incidence in this demographic, laying the groundwork for more sophisticated risk prediction models that improve the precision and specificity of stroke risk evaluations. [ABSTRACT FROM AUTHOR]

Based on the background of oilfield chemical flooding produced liquid treatment projects, to achieve new insight into the micromechanism of the impact of polymer molecules applied to enhanced oil recovery (EOR) technology on the crude oil−water interface behavior, different "crude oil/HPAM/produced water" interface simulation systems were constructed by regulating the polymerization degree and hydrolysis degree of partially hydrolyzed polyacrylamide (HPAM) and combining the composition and physical properties of oil and water phases. The simulated results showed that all simulation systems have a stable layer order and clear crude oil−water interface after dynamic relaxation equilibrium. HPAM molecules were agglomerated in different forms at the crude oil−water interface depending on the inorganic cations in the water phase and their own degree of polymerization and hydrolysis, and the order of inorganic cations aggravating the agglomeration was Ca2+>Na+>K+>Mg2+. The stability of the interfacial film was positively correlated with the gyration radius of the HPAM molecules. Unlike the continuous increase in the gyration radius of HPAM molecules with increasing polymerization degree, the effect of increasing hydrolysis degree on the stability of the crude oil−water interfacial film is concentrated in the range of 15–35%, the gyration radius of HPAM molecules no longer increases when the hydrolysis degree continues to increase, and the interfacial film stability no longer significantly changes. [Display omitted] • A multicomponent molecular dynamics crude oil−water interfacial simulation system is established according to the experimental results. • Oil−water interfacial behavior of "blanket" shaped agglomerated HPAM molecules. • The micromechanism of inorganic ions accelerating HPAM agglomeration and the order of impact ability were revealed. • Available approach for characterizing HPAM polymerization degree and hydrolysis degree on the stability of crude oil−water interfacial film. [ABSTRACT FROM AUTHOR]

In order to develop methods to further enhance oil recovery after water flooding in low permeability reservoirs by improving oil displacement efficiency, the displacement mechanism of residual oil was studied by the application of different pertinent measures. For in-depth investigation of oil displacement and variations in residual oil saturation, a large number of visual glass model displacement experiments were performed with different methods, such as changing the displacement direction, cyclic water flooding, displacement pressure difference variation and polymer flooding. In this paper, the models were divided into three (low, medium and high) permeability levels, and the residual oil after water flooding was categorized in five different types: cluster, oil film, oil drop, columnar and blind end residual oil. The experimental results showed that cluster residual oil accounted for the largest proportion after water flooding. In addition, with the increase in model permeability, cluster residual oil saturation increased and other types of residual oil saturations decreased. Compared to other methods, polymer flooding showed maximum displacement efficiency for the same displacement pressure and permeability model. The procedure was then followed by changing the displacement direction, cyclic water flooding and changing the displacement pressure difference. The different residual oil types can be activated by different methods, for example, cluster and columnar residual oil by changing the displacement direction, cluster and columnar residual oil by cyclic water flooding, cluster and oil drop residual oil by increasing displacement pressure difference. Moreover, all of the above mentioned five (05) types of residual oil can be activated by polymer flooding. [ABSTRACT FROM AUTHOR]

With the rapid development of crude oil reserves, energy consumption in heating increases gradually, so it is necessary to study heating effect and energy utilization. In this paper, a theoretical model of coil heating process for large floating roof crude oil tank is established, with dynamic thermal environment and variable physical parameters of oil products taken into consideration comprehensively. The influence mechanism of coil structure on the coupling characteristics of heat transfer and flow of crude oil during heating process is revealed. On this basis, the heating effect of crude oil in storage tank is evaluated from the point of view of time and space respectively. Simultaneously, the properties of energy and its quality are both considered, the effective energy utilization efficiency of crude oil in storage tank during heating process is analyzed, and an optimization method for heating coil of tank oil is proposed. The results show that the temperature of oil products in the center and bottom of the tank increases linearly with the influence of heat sources, and the temperature of oil products at the roof and wall of the tank is greatly affected by the dynamic thermal environment, which is showing a change regulation of fluctuating pattern. The heating effect is greatly affected by coil length. The increase of coil length can obviously improve the flow structure of crude oil in the tank. A larger eddy structure can be formed in a shorter period of time, which can increase the heating rate of crude oil and further reduce the non-uniformity of temperature field. However, effective energy efficiency is greatly affected by coil diameter. The increase of coil diameter increases the convective heat transfer coefficient between coil and crude oil, which promotes crude oil to absorb heat more easily from heat sources and improves the effective utilization of energy and exergy. Therefore, the heating effect and effective energy utilization of oil coil can be further optimized by changing the length and diameter of coil. Relevant research results can provide theoretical and technical support for improving the utilization efficiency of reserve energy and reducing the cost of reserve energy consumption. Image 1096075 • The temperature of oil in tank center and bottom is increasing affected by heat source. • The temperature of oil at tank roof and wall fluctuates with dynamic thermal environment. • An optimization method on the basis of heating effect and effective energy is proposed. • Coil length can obviously improve the flow structure of crude and enhance heating effect. • Coil diameter can strengthen convective heat transfer process and enhance energy efficiency. [ABSTRACT FROM AUTHOR]

Graphical abstract Highlights • The heat flow coupling characteristics are revealed in the crude oil heating process. • The tank steam coil heating process has been divided into four stages. • The variations of crude oil temperature and flow field heated by different coils have been analyzed. • The heating effect evaluation indexes in the storage tank heating process have set up. Abstract Considering the factors such as ambient temperature, solar radiation, heating steam pressure and physical properties of oil products, a theoretical model for heating process of large floating roof tank coil is established. The numerical solution technology of the crude oil temperature field and flow field is studied to reveal the coupling characteristics of crude oil heat transfer and flow during the storage tank heating process. Furthermore, the influence law of different coil structures on the temperature field and flow field during the crude oil heating process is discussed. On this basis, the evaluation indexes of the heating effect on the crude oil storage tank is set up, which are combined with heating rate and uniform degree of temperature field. The results show that according to variations of crude oil flow field in the tank, the tank steam coil heating process has been divided into four stages including natural convection formation, small vortex formation, large vortex formation and large vortex development. The coil structures have great influence on the temperature field and the flow field of the crude oil tank. The vertical structure and the stereoscopic structure coils will form a certain thickness low temperature zone at the tank bottom during heating process, but the serpentine structure coil will form a heated dead zone at vertex angle and base corner of the tank where area is relatively small. On this basis, comparing the heating effect of the three kinds of coils, it is found that the heating rate of serpentine structure coil is the fastest and more stable. The uniform degree of temperature field is affected by the oil liquid level. Environmental temperature and other factors have little effect and the best heating effect. [ABSTRACT FROM AUTHOR]

Challenges in assessing hepatitis B virus (HBV)-specific T cell immunity as an immunological biomarker still remain in chronic hepatitis B (CHB), such as the requirement of large quantities of cells. This study aims to conveniently assess HBV-specific T cells immunity in chronic HBV infected patients. We obtained T cell receptor β chains (TCRβs) from public databases and six acute hepatitis B patients to establish an HBV-specific TCRβs dataset. For some TCRs from one acute patient, their specificities and epitopes were verified. The potential HBV-specific TCRβs from CHB patients were analyzed using GLIPH2 and established dataset. By analyzing two antiviral therapy cohorts including 42 CHB patients, we showed that individuals with better therapy response may depend more on newly emerging potential HBV-specific TCRβs. In a cross-sectional study containing 207 chronic HBV infected patients, the results exhibited that the characteristics of potential HBV-specific clusters were divergent between CHB and hepatocellular carcinoma patients. Our strategy could profile potential HBV-specific TCRβ repertoire using a small blood sample, which will complement traditional methods for assessing the HBV-specific T cell immunity. • A strategy for profiling the potential HBV-specific TCRβ repertoire using a small blood sample. • Chronic hepatitis B patients with better response to therapy depend more on new TCR. • Different HBV-specific TCRβ clusters characteristics between patients with chronic hepatitis B and hepatocellular carcinoma. [ABSTRACT FROM AUTHOR]

In this paper, wax deposition in waxy crude oil transportation process was regarded as an irreversible process. Based on the entropy production rate equations, the linear phenomenological equations for the diffusion of wax molecules were derived by using the theory and method of non-equilibrium thermodynamics and heat-mass transfer. Combined with the mass and energy conservation laws, the differential equations of heat and mass transfer in the process of pipeline transportation were established, and the molecular diffusion rate of dissolved wax was solved. On the basis of this, the mathematical model of actual wax deposition rate was established by considering the attachment process and scouring process of the wax molecules. Taking an oil pipeline in Daqing as an example, the change law and influencing factors of the wax molecular diffusion coefficient, the wax deposition rate, and the net wax deposition rate were studied by numerical simulation. The wax deposition rate test results of the laboratory loop test were compared with the theoretical calculation results in order to analyze the accuracy and the adaptability of heat and mass coupling mechanism and to provide a theoretical basis for further study of wax deposition in the process of waxy oil pipeline transportation. [ABSTRACT FROM AUTHOR]

Based on the phase equilibrium model of the paraffin wax precipitation in the process of oil pipeline transportation, theory and method of non-equilibrium thermodynamics were applied to obtain the linear phenomenological equations for the cross-interaction of heat and mass transfer during pipeline transport, which were derived from the irreversible entropy production rate equation. Then, the analysis of the irreversible heat flow and the mass flow were carried out, and the mathematical expressions of the phenomenological coefficient of liquid phase, the phenomenological coefficient of solid phase flow, and the heat flow phenomenological coefficient were obtained. Taking a waxy crude oil transportation pipeline in Daqing Oilfield as an example, based on the analysis of liquid–solid phase equilibrium, the irreversible linear phenomenological mechanism of heat and mass coupling in waxy crude oil pipeline transportation was analyzed in detail from three levels: phenomenological coefficients which reflect characteristic of the effect of force on flow in heat and mass transfer; thermodynamic forces which trigger heat and mass transfer; transmitted heat and mass flow density, providing a theoretical basis for the further study of the wax deposition in the process of pipeline transportation. [ABSTRACT FROM PUBLISHER]

Based on the technological requirements related to waxy crude oil pipeline transportation, both unavoidable and avoidable destroyed exergy are defined. Considering the changing characteristics of flow pattern and flow regime over the course of the oil transportation process, a method of dividing station oil pipelines into transportation intervals is suggested according to characteristic temperatures, such as the wax precipitation point and abnormal point. The critical transition temperature and the specific heat capacity of waxy crude oil are calculated, and an unavoidable destroyed exergy formula is derived. Then, taking the Daqing oil pipeline as an example, unavoidable destroyed exergy in various transportation intervals are calculated during the actual processes. Furthermore, the influential rules under various design and operation parameters are further analyzed. The maximum and minimum unavoidable destroyed exergy are 381.128 kJ/s and 30.259 kJ/s. When the design parameters are simulated, and the maximum unavoidable destroyed exergy is 625 kJ/s at the diameter about 250 mm. With the increase of insulation layer thickness, the unavoidable destroyed exergy decreases continuously, and the minimum unavoidable destroyed exergy is 22 kJ/s at 30 mm. And the burial depth has little effect on the unavoidable destroyed exergy. When the operation parameters are simulated, the destroyed exergy increases, but it is less affected by the outlet pressure. The increase amplitude of unavoidable destroyed exergy will not exceed 2% after the throughput rises to 80 m3/h. When the outlet temperature increases until 65 °C, the loss increase range will not exceed 4%. Thus, this study provides a theoretical basis for the safe and economical transportation of waxy crude oil. [ABSTRACT FROM AUTHOR]