Liquid Shear Stress Research Articles

Thin Liquid Film View and Shear Stress During the Sliding of Air Bubbles on Tilted Plates.

The challenge when studying the impact and sliding of free-rising air bubbles on tilted surfaces is an experimental limitation in obtaining the film thickness of thin liquid film (TLF) during the bubbles' sliding on tilted surfaces. In this work, spatiotemporal evolution in the film thickness of the moving TLF between a sliding air bubble and a tilted plate was monitored by using a two-wavelength synchronized reflection interferometry microscopy (SRIM) technique. The evolution of the film thickness was directly determined from a timed series of monochromatic interference fringes recorded simultaneously at two different wavelengths. From the film thickness profile, a shear stress map at a given time was determined at different bubble sizes and inclination angles. Results showed that the film thickness of TLFs during the bubbles' sliding on tilted surfaces was in the range of 300-1200 nm, depending on bubble size and tilting angles. Sliding of air bubbles on tilted plates over a thin gap with a few hundred nanometers thickness yielded shear stress in the order of 10-50 Pa. Both the larger bubble size and higher tilting angles yielded a higher shear stress. Experimental results were quantitatively compared to numerical results obtained using the Reynolds lubrication theory. A good match between the two results was achieved. Numerical results suggested that a maximum shear stress exerted on a tilted plate occurred at a 25° tilting angle. This is the first time that the spatiotemporal evolution of TLF during bubbles' sliding on tilted surfaces has been achieved, and the shear stress exerted on the tilted surface has been directly determined.

Fabrication Strategies for Bioinspired and Functional Lung‐on‐Chips

AbstractLung‐on‐chips (LoCs) are advanced microsystems designed to culture pulmonary cells under physiologically relevant conditions, including air–liquid interface, cell stretch, and shear stress. As the most promising preclinical models, the LoCs are aimed to reduce and ultimately replace conventional ineffective animal studies. Biomimetic and functional LoCs lead to more translational preclinical studies that effectively address unmet needs across therapeutic areas. A variety of cell‐ and scaffold‐based techniques are employed to establish biomimetic pulmonary cell models that closely resemble their in vivo counterparts, which is a challenging yet critical aspect of LoCs. Herein, the challenges encountered in biomimetic LoCs are discussed, and the future perspectives toward higher biomimicry using advanced biofabrication approaches are explored.

Improved Two-Fluid Model for Segregated Flow and Integrated Multiphase Flow Modeling for Downhole Pressure Predictions

This work presents an integrated multiphase flow model for downhole pressure predictions with the purpose of producing relatively more accurate predictions under wide-flowing conditions while maintaining a simple form. As a component of the integrated model, an improved two-fluid model for segregated flow is proposed. The new two-fluid model was developed by improving the modeling of the wetted perimeters and the liquid wall shear stress. It outperformed five other existing state-of-the-art models in predicting the liquid holdup and pressure gradient of 11 experimental datasets from the literature, with an average relative error of 37.6% for liquid holdup predictions and 24.0% for pressure gradient predictions. The model succeeds in capturing the effects of inclination angle, pressure or gas density, and liquid and gas superficial velocities on liquid holdup and pressure gradient. The integrated model incorporates the state-of-the-art onset of liquid loading predictive model and classifies the flow into two major categories based on the onset of liquid loading that are modeled by two different approaches, respectively. It outperformed the other multiphase flow models in predicting the downhole pressure of 313 field data points, especially the wells that have both segregated and intermittent (mixed) flows. The errors were reduced to 4.4% for the field cases with mixed flow regions and 5.1% for all the field data points.

Viscometer for investigating the viscosity of magnetic fluid media

The rational application of magnetic fluids in various technical systems requires their stability analysis, hydrodynamic particle size, dissipative processes in the colloid control. The existing viscometers do not fully meet all requirements, in particular, they do not allow research in a magnetic field of given magnitude and certain topography. It is proposed to determine rheological properties of magnetic fluids using rotary viscometer, in which two measuring gaps are structurally designed and filled with studied fluid, which is important for calculating characteristics of low viscosity magnetic media. The device design implements practically homogeneous magnetic field, varying within wide range and directed perpendicular to liquid shear stress. The device allows to steadily maintain shear rate in medium under study, and to determine viscosity with a sufficiently large change. A small magnetic fluid volume is required to estimate rheological characteristics. The accuracy of measurements of the internal friction force, device heating temperature, coaxial cylinders rotation speed and magnetic field inside investigated medium meet the requirements of international standards. Laminar fluid flow process in the device gap is described mathematically. This made it possible to justify the construction geometrical dimensions in order to increase the measurements and determine rheological properties of low-viscosity magnetic materials. The formulas for calculation of Newtonian fluid viscosity coefficient, shear stress and shear rate based on experimental data were obtained.

Prediction model of critical liquid‐carrying gas velocity for high gas‐to‐liquid ratio gathering pipelines

As the pressure and temperature of natural gas pipelines decreases during operation, water and condensate accumulates form in the low areas of the pipelines, affecting the operational efficiency of the pipelines and even corroding them. The critical gas velocity is a key factor in predicting liquid loading onset in the pipeline, so that appropriate measures can be taken in advance and hazards can be reduced. This paper proposes a model for predicting pipeline liquid loading onset based on the liquid film and wall shear stress of zero, and applicable to different pipe diameters and different inclination angles. This model provides a more simplified and comprehensive prediction of pipeline fluid loading than other models with complex calculations. The critical gas velocity in this model is a function of the liquid holding rate rather than the liquid film thickness, and the critical gas velocity prediction in a phase-inclined pipe is carried out by an improved Belfroid angle correction term. The experimental data, field data and seven models in the published literature were compared and validated, and the errors were judged. The results showed that the new model outperformed the other models in terms of absolute mean error at full inclination angle, and was able to predict the pipeline liquid loading accurately.

Computational investigation of nasal surface coverage from squeeze bottle and Neti Pot saline irrigation flow

Background and objective: Nasal saline irrigation is a common therapy for inflammatory nasal and paranasal disease or for managing post nasal and sinus surgery recovery. Two common irrigation devices include the netipot and squeeze bottles, where anecdotally, these devices alleviate congestion, facial pain, and pressure. However, a quantitative evaluation of these devices’ performance and the fluid dynamics responsible for the irrigation distribution through the nose is lacking. This study tracked the liquid surface coverage and wall shear stresses during nasal saline irrigation produced from a Neti Pot and squeeze bottle.Methods: This study used transient computational fluid dynamics (CFD) simulations to investigate the saline irrigation flow field in a subject-specific sinonasal model. The computational nasal cavity model was constructed from a high-resolution computed tomography scan (CT). The irrigation procedure applied a head position tilted at 90° forward using an 80 ml squeeze bottle and 120 ml Neti Pot.Results: The results from a single sinonasal model demonstrated that the Neti Pot irrigation was more effective in delivering saline solution to the nasal cavity on the contralateral side of irrigation due to typically larger volumes but at the expense of reduced flow and shearing rates, as the flow entered under gravitational forces. The squeeze bottle irrigation provided greater surface coverage on the side of irrigation.Conclusions: The results from the single patient model, demonstrated the Neti Pot increased surface coverage in the paranasal sinuses. Reducing the jet diameter may aid the direct targeting of a specific region at the side of irrigation by preventing the impingement of the jet to the nasal passage surface and redirection of the flow. Evaluating this performance across a wider cohort of patients can strengthen the findings.

Analysis of Fractional Thin Film Flow of Third Grade Fluid in Lifting and Drainage via Homotopy Perturbation Procedure

Analysis of thin film flows is an important topic in fluid dynamics due to the large number of industrial applications such as food processing, chip manufacturing, irrigation, oil refining process, painting finishing, etc. Analysis involves studying the effects of various parameters in absolute conditions. These parameters may be film thickness, volumetric flux, liquid velocity profile, viscosity, shear stress, gravity, density, and different boundary formations. We have expanded the formulations of non-Newtonian third grade fluid for lifting and draining in fractional space. Fractional calculus along with Homotopy Perturbation Method is used for the solution and analysis purposes. The suitability and consistency of the solutions is determined by detecting residuals in each case. Velocity profile, average velocity, and volume flow for lifting and drainage cases are calculated. To the best of authors knowledge, thin film flow of fractional third grade fluid is not attempted before in lifting and drainage. Investigation shows increase in value of fractional parameter that decreases the velocity profile in lifting while increases the velocity in drainage scenario. Also, the frictional parameter and the gravitational parameter have opposite, while material constant has direct relationship with the velocity profile in lifting case. All the parameters showed inverse effect on the velocity in drainage case.

A Detailed Hydrodynamic Study of the Split-Plate Airlift Reactor by Using Non-Invasive Gamma-Ray Techniques

This study focused on detailed investigations of selected local hydrodynamics in split airlift reactor by using an unconventional measurements facility: computed tomography (CT) and radioactive particle tracking (RPT). The local distribution in a cross-sectional manner with its radial’s profiles for gas holdup, liquid velocity flow field, shear stresses, and turbulent kinetic energy were studied under various gas velocity 1, 2 and 3 cm/s with various six axial level z = 12, 20, 40, 60, 90 and 112 cm. The distribution in gas–liquid phases in the whole split reactor column, the riser and downcomer sides, including their behavior at the top and bottom sections of the split plate was also described. The outcomes of this study displayed an exemplary gas–liquid phases dispersion approximately in all reactor’s zones and had large magnitude over the ring of the sparger as well as upper the split plate. Furthermore, the outcomes pointed out that the distribution of this flow may significantly impacts the performance of the split reactor, which may have essential influence on its performance particularly for microorganisms culturing applications. These outcomes are dependable as benchmark information to validate computational fluid dynamics (CFD) simulations and other models.

Mesoscale model of radial hydrodynamics for fluidizing small particles with low solid holdup in gas-liquid-solid circulating fluidized bed

Gas-liquid-solid circulating fluidized bed (GLSCFB) is an important reactor. Radial hydrodynamics of GLSCFB are critical for the industrial design and scale-up, but the hydrodynamics have not been well described. To mechanically model the radial flow structures, a mesoscale method based on the energy-minimization multiscale principle is applied. A comparison between experimental data and model calculations shows that the radial mesoscale model can reasonably predict the radial distributions of the flow parameters and analyze the influence of the operating conditions on the radial hydrodynamics in GLSCFB for fluidizing solid particles of small diameters (dp ≤ 1 mm) and low solid holdup (εs ≤ 15%). Additionally, model predictions show that the peak positions of the suspension and transportation energy consumed per unit mass of solid particles and liquid shear stress range from 0.75 to 0.9, which is an obvious indicator of the radial flow structure.

Preparation and characterization of microbubbles with a porous ceramic membrane

The efficient preparation of microbubbles is very meaningful due to the wide applications of microbubbles in water treatment, food industry, cosmetics, and pharmaceuticals industry. In this work, a flow system based on commercial porous ceramic membrane is developed for controllable generation and rapid characterization of microbubbles. The images of generated microbubbles in the visualization cell are captured by a CCD on the microscope, and the size and distribution of microbubbles can be rapidly obtained with MATLAB. The influences of liquid flow velocity, liquid viscosity, surface tension, membrane pore size and gas superficial velocity on the microbubble size are systematically studied. To increase the liquid flow velocity and corresponding liquid shear stress, a stainless-steel rod is inserted into the middle of ceramic membrane, which can effectively decrease the bubble size. Under the optimal experimental conditions, the microbubbles with the diameter of 64∼87 μm are continuously prepared. A mathematical model is developed which can predict the microbubbles size under different conditions, which is useful for the understanding and design of microbubble generation.

Toward the Clinical Development and Validation of a Thy1-Targeted Ultrasound Contrast Agent for the Early Detection of Pancreatic Ductal Adenocarcinoma.

We recombinantly expressed the Thy1-scFv with a carboxy-terminus cysteine residue to facilitate its thioether conjugation to the PEGylated MBs presenting with maleimide functional groups. After the scFv-MB conjugations, we tested binding activity of the MBThy1-scFv to MS1 cells overexpressing human Thy1 (MS1Thy1) under liquid shear stress conditions in vitro using a flow chamber setup at 0.6 mL/min flow rate, corresponding to a wall shear stress rate of 100 seconds, similar to that in tumor capillaries. For in vivo Thy1 US molecular imaging, MBThy1-scFv was tested in the transgenic mouse model (C57BL/6J - Pdx1-Cre; KRas; Ink4a/Arf) of PDAC and in control mice (C57BL/6J) with L-arginine-induced pancreatitis or normal pancreas. To facilitate its clinical feasibility, we further produced Thy1-scFv without the bacterial fusion tags and confirmed its recognition of human Thy1 in cell lines by flow cytometry and in patient PDAC frozen tissue sections of different clinical grades by immunofluorescence staining. Under shear stress flow conditions in vitro, MBThy1-scFv bound to MS1Thy1 cells at significantly higher numbers (3.0 ± 0.8 MB/cell; P < 0.01) compared with MBNontargeted (0.5 ± 0.5 MB/cell). In vivo, MBThy1-scFv (5.3 ± 1.9 arbitrary units [a.u.]) but not the MBNontargeted (1.2 ± 1.0 a.u.) produced high US molecular imaging signal (4.4-fold vs MBNontargeted; n = 8; P < 0.01) in the transgenic mice with spontaneous PDAC tumors (2-6 mm). Imaging signal from mice with L-arginine-induced pancreatitis (n = 8) or normal pancreas (n = 3) were not significantly different between the two MB constructs and were significantly lower than PDAC Thy1 molecular signal. Clinical-grade scFv conjugated to Alexa Fluor 647 dye recognized MS1Thy1 cells but not the parental wild-type cells as evaluated by flow cytometry. More importantly, scFv showed highly specific binding to VEGFR2-positive vasculature and fibroblast-like stromal components surrounding the ducts of human PDAC tissues as evaluated by confocal microscopy. Our findings summarize the development and validation of a clinically relevant Thy1-targeted US contrast agent for the early detection of human PDAC by US molecular imaging.

Wave characteristics of vertical upward adiabatic annular flow in pipes

Annular flow exists in many engineering applications, such as refrigerators, oil extraction, nuclear reactors and so on, due to its high heat and mass transfer efficiencies. Annular flow is characterized by liquid film on the wall and gas core at the center of the flow duct. The interface between the gas and liquid is composed of many different waves that play important role in mass, momentum and energy transfers between gas and liquid phases. Here three important parameters regarding wave characteristics, namely, wave velocity, base film thickness and wave height have been studied. For wave velocity, correlation has been proposed by two methods which are derived from liquid interfacial velocity and interfacial shear stress, respectively. For correlations of base film thickness and wave height, they are proposed in similar forms as that of average film thickness previously developed by the authors. These newly proposed correlations are functions of gas and liquid Weber numbers, and are simpler and more straightforward to use as compared to the existing ones. The newly proposed wave velocity, base film thickness and wave height correlations, respectively, have mean absolute percentage errors of 9.56%, 14.6% and 12.1% compared to current databases. They have shown an improved prediction accuracy compared to the other correlations in the literature.

Numerical study on bubble-liquid two-phase turbulent hydrodynamics in extremely narrow shape bioreactor

The main objective of this work was to determine the influence of the bubble-liquid two-phase turbulent hydrodynamics on cell culture in extremely narrow shape bioreactor. An improved second-order moment bubble-liquid turbulent model and built in-house calculation source code were developed to numerically simulate the hydrodynamics that related to cell damage. Two higher gas entrance velocities of 78.3 m/s and 104.4 m/s were employed and their effects on hydrodynamic parameters, such as bubble rising and liquid flow velocities, bubble normal and shear stresses, correlation of bubble-liquid normal stresses, turbulent kinetic energy and turbulent energy dissipation rate of bubble and liquid were investigated details. All increased with gas entrance velocities increase but failed to explain an experimental observation that higher cell death at jetting region. A new correlation definition, bubble-liquid two-phase turbulent energy production term was proposed to successfully elaborate it, as well as the effects of high gas entrance velocities. Simulation results showed turbulent energy production terms are the largest at near gas jetting regions in comparison to those of developed flow regions, which are in good agreements with experimental result. Furthermore, extremely narrow shape deteriorated the cell living environment.

CFD modeling of liquid film reversal of two-phase flow in vertical pipes

The phenomenon of two-phase flows is characterized by its wide range of presence in nature and industrial applications. In gas and oil production, the simultaneous two-phase flow of gases and liquids often occurs in gas wells. The produced gases flow rate decreases over the years until reaching a critical flow rate when they lose their ability to lift the associated liquids upward and the liquid film reverses direction, which triggers liquid loading. Liquid loading causes the produced liquids to accumulate in the bottom of the wellbore, which causes a high back pressure that reduces the well production rate till production is ceased eventually. The critical gas velocity exists in the churn flow regime which is mainly characterized by the oscillatory behavior of the liquids flow field. This study employs CFD techniques to model the churn flow in a 3-inch-diameter vertical pipe near the critical gas flow rate for different liquid flow rates. This work utilizes the two-fluid Eulerian model along with the RNG (Re-Normalization Group) k-ε turbulence model to investigate the behavior of the flow field in a two-dimensional axisymmetric computational domain. Simulations were carried out using the commercial software ANSYS Fluent 18.2 with air and water as the two working fluids. The model results showed a good agreement with the experimental data and proved the mesh and time independence of the model. Oscillatory behaviors of the liquid film flow rate, shear stress, and pressure were observed along with the formation of interfacial waves. Detailed information about the velocity, shear stress, and pressure behaviors is presented. Accordingly, recommendations are suggested for future considerations.

Effect of crossflow regime on the deposit and cohesive strength of membrane surface fouling layers

Acquiring knowledge of the properties of membrane fouling layers is crucial to mitigating fouling and developing cleaning strategies. The cohesive strength of these fouling layers, which determines the cleaning requirement of the membrane, is nevertheless rarely investigated. Here we introduced fluid dynamic gauging (FDG) to the crossflow microfiltration of a wood material, namely microcrystalline cellulose (MCC, nominal particle size 20 μm, 95% (in volume) of the particles are bigger than 5.4 μm and smaller than 56.4 μm), to study in situ the cohesive strength of the membrane surface fouling formed under different crossflow regimes. Using regenerated cellulose membrane with a nominal pore size of 0.2 μm, filtration experiments with FDG measurement show that the crossflow regime can lead to the formation of surface fouling layers with distinct cohesive strength. Fouling formed in turbulent/transitional crossflow (Reynolds number, Reduct = 4170) was stronger and its removal required more liquid shear stress compared to the layers formed in laminar crossflow (Reduct = 1560). The fouling layers that can withstand the minimum shear of 35 Pa from the FDG sensor with turbulent/transitional crossflow were, on average 294 ± 10 μm thick, in contrast to those formed in laminar crossflow, which were significantly thinner (144 ± 73 μm at 35 Pa shear stress, p < 0.05). On the other hand, turbulent/transitional crossflow reduced material deposition significantly (p < 0.05). After 1000 s filtration, 0.117 ± 0.003 kg m−2 MCC were found on the turbulent/transitional crossflow membranes, compare to 0.134 ± 0.005 kg m−2 in the laminar crossflow situation. Moreover, a similar permeate flux was observed in all experiments. Therefore, this work also highlights the necessity of developing membrane cleaning protocols based on the fouling layer properties, rather than on the permeate flux decline.

Thixotropic properties of multi-functional binder and compaction behaviour of the low alloyed binder-treated powder

ABSTRACTA new multi-functional binder with adhesive and lubricant effect was designed, and the thixotropic properties of the binder components and the resulting binder, the adhesive effect and compaction behaviour of the binder-treated powder were investigated. The results demonstrate that the thixotropic components in the binder are polyethylene wax and microcrystalline wax. With the increase of polyethylene wax content, the critical solid–liquid shear stress of binders decreases gradually. The main lubrication components in the low-pressure and high-pressure stages during the compaction process are found to be polyethylene wax and microcrystalline wax, respectively. The fine metal or graphite additives are effectively bonded on the surface of iron particles and filled in the pits. The green density reaches 7.25 g cm−3 at 600 MPa when the content of polyethylene wax is 30%. From 400 to 750 MPa, the content of polyethylene wax corresponding to the minimum ejection pressure decreases from 20 to 0%.

Mixing characteristics, cell trajectories, pressure loss and shear stress of tubular photobioreactor with inserted self‐rotating helical rotors

AbstractBACKGROUNDTubular photobioreactors (TPBRs) have great potential in culturing microalgae, but their poor mixing properties make it difficult to increase the surface productivity. In this work, a TPBR with inserted self‐rotating helical rotors, which have been under study for a decade, was designed.RESULTSThis paper aimed to show hydrodynamic behaviors of gas–liquid in a TPBR with inserted self‐rotating helical rotors by computational fluid dynamics (CFD) and visualization experiments. It can be concluded that by assembling self‐rotating helical rotors into the TPBR, very remarkable mixing and particle cycle frequencies were achieved. Besides, the influences of rotor lead and liquid inlet velocity on the swirl number, the gas and liquid average circumferential velocities, pressure loss, cell trajectories and shear stress were also investigated. The best choice was to select a rotor lead of 150 mm and a liquid inlet velocity of 0.4–0.5 m s‐1 for microalgae with strong shear force tolerance. Microalgae cultivation experiments verified that helical rotors had a positive effect on biomass productivity.CONCLUSIONThe results indicated that assembling the self‐rotating helical rotors into TPBR was a feasible and effective method to improve the mixing performance and microalgae productivity. © 2017 Society of Chemical Industry

Nonequilibrium all-atom molecular dynamics simulation of the bubble cavitation and application to dissociate amyloid fibrils.

The cavitation of gas bubbles in liquids has been applied to different disciplines in life and natural sciences, and in technologies. To obtain an appropriate theoretical description of effects induced by the bubble cavitation, we develop an all-atom nonequilibrium molecular-dynamics simulation method to simulate bubbles undergoing harmonic oscillation in size. This allows us to understand the mechanism of the bubble cavitation-induced liquid shear stress on surrounding objects. The method is then employed to simulate an Aβ fibril model in the presence of bubbles, and the results show that the bubble expansion and contraction exert water pressure on the fibril. This yields to the deceleration and acceleration of the fibril kinetic energy, facilitating the conformational transition between local free energy minima, and leading to the dissociation of the fibril. Our work, which is a proof-of-concept, may open a new, efficient way to dissociate amyloid fibrils using the bubble cavitation technique, and new venues to investigate the complex phenomena associated with amyloidogenesis.

Scale effects in nano-channel liquid flows

Force-driven liquid argon flows both in nanoscale periodic domains and in gold nano-channels are simulated using non-equilibrium molecular dynamics to investigate the scale and wall force field effects. We examined variations in liquid density, viscosity, velocity profile, slip length, shear stress and mass flow rate in different sized periodic domains and nano-channels at a fixed thermodynamic state. In the absence of walls, liquid argon obeys Newton’s law of viscosity with the desired absolute viscosity in domains as small as 4 molecular diameters in height. Results prove that deviations from continuum solution are solely due to wall effects. Simulations in nano-channels with heights varying from 3.26 to 36 nm exhibit parabolic velocity profiles with constant slip length modeled by Navier-type slip boundary condition. Both channel averaged density and “apparent viscosity” decrease with reduced channel height, which has competing effects in determination of the mass flow rate. Density layering and wall force field induce deviations from Newton’s law of viscosity in the near-wall region, while constant “apparent viscosity” with the deformation rate from a parabolic velocity profile successfully predicts shear stress in the bulk flow region.

Construction of an Aptamer-SiRNA Chimera-Modified Tissue-Engineered Blood Vessel for Cell-Type-Specific Capture and Delivery.

The application of tissue-engineered blood vessels (TEBVs) is the main developmental direction of vascular replacement therapy. Due to few and/or dysfunctional endothelial progenitor cells (EPCs), it is difficult to successfully construct EPC capture TEBVs in diabetes. RNA has a potential application in cell protection and diabetes treatment, but poor specificity and low efficiency of RNA transfection in vivo limit the application of RNA. On the basis of an acellular vascular matrix, we propose an aptamer-siRNA chimera-modified TEBV that can maintain a satisfactory patency in diabetes. This TEBV consists of two parts, CD133-adenosine kinase (ADK) chimeras and a TEBV scaffold. Our results showed that CD133-ADK chimeras could selectively capture the CD133-positive cells in vivo, and then captured cells can internalize the bound chimeras to achieve RNA self-transfection. Subsequently, CD133-ADK chimeras were cut into ADK siRNA by a dicer, resulting in depletion of ADK. An ADK-deficient cell may act as a bioreactor that sustainably releases adenosine. To reduce nonspecific RNA transfection, we increased the proportion of HAuCl4 during the material preparation, through which the transfection capacity of polyethylenimine (PEI)/polyethylene glycol (PEG)-capped gold nanoparticles (PEI/PEG-AuNPs) was significantly decreased and the ability of TEBV to resist tensile and liquid shear stress was greatly enhanced. PEG and 2'-O-methyl modification was used to enhance the in vivo stability of RNA chimeras. At day 30 postgrafting, the patency rate of CD133-ADK chimera-modified TEBVs reached 90% in diabetic rats and good endothelialization was observed.