Study on the thixotropy and structural recovery characteristics of waxy crude oil emulsion

Waxy crude oil emulsion has thixotropic properties at the temperature near gel point,which is a macromechanical characterization of the structure failure and recovery of waxy crude oil emulsion.In this paper,the thixotropic behaviors of waxy crude oil emulsion near gel point were studied using hysteresis loop formed by stress linear increase and decrease,as well as the structural recovery characteristics.The influence of the loading conditions and water content on the thixotropy of waxy crude oil emulsion were analyzed with hysteresis loop area.The concept of"structural recovery"was introduced to study the degree of structural recovery after different stewing,and influencing factors were taken into account.Results have shown that for waxy crude oil emulsion,the failure to fully restore of the structure after lysis is the cause of the formation of hysteresis loop,and the loading conditions will not affect the strength of thixotropy and the degree of structural recovery.Additionally,the dispersed phase droplets weaken the thixotropy and structure recovery characteristics of waxy crude oil emulsion,and the greater the water content,the weaker the thixotropy.The findings can help to better understand the safe and economic operation of waxy crude oil-water pipeline transportation.

Robust signal recovery algorithm for structured perturbation compressive sensing

It is understood that the sparse signal recovery with a standard compressive sensing（CS） strategy requires the measurement matrix known as a priori. The measurement matrix is, however, often perturbed in a practical application.In order to handle such a case, an optimization problem by exploiting the sparsity characteristics of both the perturbations and signals is formulated. An algorithm named as the sparse perturbation signal recovery algorithm（SPSRA） is then proposed to solve the formulated optimization problem. The analytical results show that our SPSRA can simultaneously recover the signal and perturbation vectors by an alternative iteration way, while the convergence of the SPSRA is also analytically given and guaranteed. Moreover, the support patterns of the sparse signal and structured perturbation shown are the same and can be exploited to improve the estimation accuracy and reduce the computation complexity of the algorithm. The numerical simulation results verify the effectiveness of analytical ones.

Orchestrated cellular,biochemical,and biomechanical optimizations endow platelet-rich plasma-based engineered cartilage with structural and biomechanical recovery

Recently,biomaterials for cartilage regeneration has been intensively investigated.However,the development of scaffolds that capture regenerated cartilage with biomechanical and structural recovery has rarely been reported.To address this challenge,platelet-rich plasma(PRP)-based cartilage constructs with a well-orchestrated symphony of cellular,biochemical and biomechanical elements were prepared by simultaneously employing chondrogenic progenitor cells(CPCs)as a cell source,optimizing platelet concentration,and adding an enzyme-ion activator.It was shown that this triple-optimized PRP+CPC construct possessed increased biomechanical properties and suitable biochemical signals.The following in vitro study demonstrated that the triple-optimized PRP+CPC constructs generated cartilage-like tissue with higher expression levels of chondrogenic-specific markers,more deposition of cartilage-specific extracellular matrix(ECM),and greater biomechanical values than those of the other constructs.Twelve weeks after the construct was implanted in a cartilage defect in vivo,histological analysis,qPCR,and biomechanical tests collectively showed that the triple-optimized constructs yielded a more chondrocyte-like cell phenotype with a higher synthesis of Col-Ⅱand aggrecan.More importantly,the triple-optimized constructs facilitated cartilage regeneration with better biomechanical recovery than that of the other constructs.These results demonstrate the efficacy of the triple-optimization strategy and highlight the simplicity and potency of this PRP+CPC construct for cartilage regeneration.