In order to investigate the apoptotic pathway of rabbit annulus fibrosus(AF) cells induced by mechanical overload,an experimental air-pressure model was established in this study to pressurize the rabbit AF cells in v...In order to investigate the apoptotic pathway of rabbit annulus fibrosus(AF) cells induced by mechanical overload,an experimental air-pressure model was established in this study to pressurize the rabbit AF cells in vitro.Cells were randomly divided into five groups in which the cells were exposed to a continuous pressure of 1.1 MPa for different lengths of time(0,5,12,24 and 36 h).The cell proliferation and apoptosis were detected by cell counting kit-8(CCK-8) assay and flow cytometry;the alterations in mitochondrial membrane potential were measured by fluorescence microscopy and fluorescence spectrophotometer;the activities of caspase-8 and 9 were determined by spectrophotometry.The results showed that after the cells were subjected to the pressure for 24 or 36 h,the cell proliferation was inhibited;the ratio of cell apoptosis was increased;the mitochondrial membrane potential was decreased;the activity of caspase-9 was enhanced;no activity changes were observed in caspase-8.The results suggested that treatment with a pressure of 1.1 MPa for more than 24 h can lead to the proliferation inhibition and the apoptosis of rabbit AF cells in vitro,and the mitochondrial-dependent pathway is implicated in the pressure-induced AF cell apoptosis.展开更多
Improving the closure effect of surgical suture for repair of annulus fibrosus defects remains an unsolved problem.A new type of porcine fibrin glue was reported for the repair of annulus fibrous defects in sheep mode...Improving the closure effect of surgical suture for repair of annulus fibrosus defects remains an unsolved problem.A new type of porcine fibrin glue was reported for the repair of annulus fibrous defects in sheep models in this study.Continuous axial loading test showed that this glue could effectively improve the closure effect of surgical suture for annulus fibrous defect.Magnetic resonance imaging (MRI) of the lumbar spine confirmed that,compared with nonfibrin glue treated intervertebral discs,it contributed to preservation of the nucleus pulposus and maintained the physiological hydration of the intervertebral discs.Moreover,histomorphology evaluation showed that the porcine fibrin glue could partially reverse degeneration of the injured intervertebral discs.Taken together,porcine fibrin glue can effectively enhance the closure effect of surgical suture on annulus fibrosus,improve the repair effect and slow down the degeneration of the intervertebral disc,and provide a potential therapeutic strategy for degenerative intervertebral disc disease.展开更多
The present work relates to a numerical investigation of double diffusive mixed convection around a horizontal annulus with a finned inner cylinder.The solutal and thermal buoyancy forces are sustained by maintaining ...The present work relates to a numerical investigation of double diffusive mixed convection around a horizontal annulus with a finned inner cylinder.The solutal and thermal buoyancy forces are sustained by maintaining the inner and outer cylinders at uniform temperatures and concentrations.Buoyancy effects are also considered,with the Boussinesq approximation.The forced convection effect is induced by the outer cylinder rotating with an angular velocity(ω)in an anti-clockwise direction.The studies are made for various combinations of dimensionless numbers;buoyancy ratio number(N),Lewis number(Le),Richardson number(Ri)and Grashof number(Gr).The isotherms,isoconcentrations and streamlines as well as both average and local Nusselt and Sherwood numbers were studied.A finite volume scheme is adopted to solve the transport equations for continuity,momentum,energy and mass transfer.The results indicate that the use of fins on the inner cylinder with outer cylinder rotation,significantly improves the heat and mass transfer in the annulus.展开更多
The convective heat transfer of hybrid nanoliquids within a concentric annulus has wide engineering applications such as chemical industries, solar collectors, gas turbines, heat exchangers, nuclear reactors, and elec...The convective heat transfer of hybrid nanoliquids within a concentric annulus has wide engineering applications such as chemical industries, solar collectors, gas turbines, heat exchangers, nuclear reactors, and electronic component cooling due to their high heat transport rate. Hence, in this study, the characteristics of the heat transport mechanism in an annulus filled with the Ag-MgO/H_2O hybrid nanoliquid under the influence of quadratic thermal radiation and quadratic convection are analyzed. The nonuniform heat source/sink and induced magnetic field mechanisms are used to govern the basic equations concerning the transport of the composite nanoliquid. The dependency of the Nusselt number on the effective parameters(thermal radiation, nonlinear convection,and temperature-dependent heat source/sink parameter) is examined through sensitivity analyses based on the response surface methodology(RSM) and the face-centered central composite design(CCD). The heat transport of the composite nanoliquid for the spacerelated heat source/sink is observed to be higher than that for the temperature-related heat source/sink. The mechanisms of quadratic convection and quadratic thermal radiation are favorable for the momentum of the nanoliquid. The heat transport rate is more sensitive towards quadratic thermal radiation.展开更多
In this study, integral operational methods are used to investigate the thermally induced transverse vibration of a thin elliptic annulus plate with elastic supports at both radial boundaries.The axisymmetric temperat...In this study, integral operational methods are used to investigate the thermally induced transverse vibration of a thin elliptic annulus plate with elastic supports at both radial boundaries.The axisymmetric temperature distribution is determined by the heat conduction differential equation and its corresponding boundary conditions by employing a unified integral transform technique by use of Mathieu functions and modified Mathieu functions. The solution of thermally induced vibration of the plate with both ends encased with elastic supports is obtained by employing an integral transform for double Laplace differential equation. The thermal moment is derived on the basis of temperature distribution, and its stresses are obtained based on resultant bending moments per unit width. The numerical calculations of the distributions of the transient temperature and its associated stress distributions are shown in the figures.展开更多
We report an acoustic focusing lens composed of two-layer annuluses made of metal cylinders in air. We find that the cylindrical waves can be focused into a perfect point without diffraction in the centre of the annul...We report an acoustic focusing lens composed of two-layer annuluses made of metal cylinders in air. We find that the cylindrical waves can be focused into a perfect point without diffraction in the centre of the annuluses, which arises from the Mie-resonance modes in the annuluses. The focusing frequencies are related to the size of the inner annulus, and the focusing effect can be applied to the annuluses with different shapes and incident positions. Interesting applications of the focusing lens in the acoustic beam splitter and directional transmitter with energy enhancement are further discussed.展开更多
Hole cleaning is a complex process as there are many variables affecting cuttings removal(e.g.drilling fluid type,density,flow rate and rheological properties,cuttings size,drill pipe rotation speed).With the increasi...Hole cleaning is a complex process as there are many variables affecting cuttings removal(e.g.drilling fluid type,density,flow rate and rheological properties,cuttings size,drill pipe rotation speed).With the increasing number of drilling small diameter wells(e.g.coiled tubing drilling applications,ultra-deep wells drilled for exploitations of unconventional oil and gas resources),the wall resistance of the micro annulus also emerges as one of the most critical factors affecting the cuttings accumulation in wellbore.The eccentricity of drill pipes commonly observed during the drilling process of ultra-deep well and coiled tubing well makes the wall resistance effect on the cuttings transport even more prominent.Understanding the wall resistance effect on the particle settling behavior in eccentric annuli is,therefore,crucial for hydraulic design of efficient cuttings transport operations in these wells.In this study,a total of 196 sets of particle settling experiments were carried out to investigate the particle settling behavior in eccentric annuli filled with power-law fluids.The test matrix included the eccentricity ranges of 0-0.80,the dimensionless diameter ranges of 0.13-0.75 and the particle Reynolds number ranges of 0.09-32.34.A high-speed camera was used to record the particle settling process and determine the influences of the eccentricity,the dimensionless diameter,the fluid rheological properties,and the solid particle characteristics on the wall factor and the particle settling velocity.The functional relationship among the dimensionless diameter,the particle Reynolds number,and the wall factor was determined by using the method of controlling variables.An eccentric annulus wall factor model with average relative error of 5.16%was established.Moreover,by introducing Archimedes number,an explicit model of particle settling velocity in the eccentric annulus with average relative error of 10.17%was established.A sample calculation of particle settling velocity was provided to show the application of the explicit model.Results of this study can be used as a guideline by field engineers to improve hydraulic design of cuttings transport operations in concentric and eccentric annuli.展开更多
Background:The surgical outcomes of tetralogy of Fallot(TOF)have evolved dramatically and have resulted in lower mortality rate.Currently,the many cardiac centers have a trend to early single-stage complete repair mor...Background:The surgical outcomes of tetralogy of Fallot(TOF)have evolved dramatically and have resulted in lower mortality rate.Currently,the many cardiac centers have a trend to early single-stage complete repair more than a staged repair.However,the patients who have an early primary repair were required transannular patch augmentation of a pulmonary valve frequently.This effect has been developed a chronic pulmonary insufficiency may lead to right ventricular dilation,dysfunction.In this era,the aim of treatment of TOF is attempted to preserve pulmonary valve annulus for prevent right ventricular dysfunction in the future.The systemic to pulmonary artery shunt is a palliative procedure or known as staged repair for symptomatic patients with TOF.The modified Blalock-Taussig shunt(mBTS)is the most useful systemic to pulmonary shunt and perform as an initial procedure before complete repair.The mBTS can provide increase pulmonary blood flow as well as improve oxygenation and also promote pulmonary artery(PA)growth.However,the effect of this procedure to promote growth of a pulmonary valve annulus is still debate.Objectives:To compare a growth of pulmonary valve annulus between after staged repair and primary repair in patients with TOF(without pulmonary atresia).Methods:A retrospective case-control study,review of patients with TOF underwent total repair at our hospitals from January 2005 and December 2017 was performed,a total number of 112 patients underwent TOF repair.Twenty-nine patients(26%)underwent a staged repair(mBTS group)and 83(74%)underwent total repair only or primary repair(PR group).We evaluated diameter of pulmonary valve annulus by using echocardiography at the time of first diagnosis and before complete repair on both groups.Results:The age of diagnosis of mBTS group were younger than PR group(p=0.011).Therefore,pulmonary valve annuls were smaller in mBTS group.(Z-score,−2.93±1.42 vs.−1.89±0.97;p=0.001).However,the growth potential of pulmonary valve annulus was increase more than PR group significantly(Z-score,−1.46±1.02 vs.−2.11±1.19;p=0.009)Even though a patent ductus arteriosus was found commonly in PR group(p=0.018).Conclusions:Our results suggest the systemic to pulmonary shunt or mBTS can promote growth of pulmonary valve annulus in patients with TOF.展开更多
The interaction of transient fully developed natural convection flow with thermal radiation inside a vertical annulus is analyzed both analytically and numerically. The Rosseland approximation is used to describe the ...The interaction of transient fully developed natural convection flow with thermal radiation inside a vertical annulus is analyzed both analytically and numerically. The Rosseland approximation is used to describe the radiative heat flux in the energy equation. The mathematical model capturing the present physical situation is highly non-linear due to the presence of radiation effect. The solution of transient model is obtained by implicit finite difference method. To check accuracy of the numerical solution, steady state solution for energy and momentum equations are derived analytically using perturbation series method. Skin-friction and Nusselt number at the outer surface of inner cylinder as well as inner surface of the outer cylinder are obtained. Selected sets of graphical results illustrating the effects of various controlling parameters involved in the problem on flow formation are discussed.展开更多
Mitral Annular Calcification (MAC) is a degenerative process involving the fibrous ring of the mitral valve. Caseous Calcification of Mitral Annulus (CCMA) is a rare variant of MAC. This condition is benign and usuall...Mitral Annular Calcification (MAC) is a degenerative process involving the fibrous ring of the mitral valve. Caseous Calcification of Mitral Annulus (CCMA) is a rare variant of MAC. This condition is benign and usually needs no treatment. This is a case report of a 67-year-old woman with non-specific symptoms in whom a cardiac tumor was suspected by transthoracic Echocardiography. The use of multi-modality imaging strategy with transesophageal Echocardiography and cardiac MR scanning revealed however the diagnosis of CCMA and spared the patient an unnecessary operation.展开更多
We report a case of supra-annular mitral valve replacement for a patient with prosthetic ring endocarditis that developed late after undergoing undersized mitral annuloplasty (UMAP). A 58-year-old man had undergone le...We report a case of supra-annular mitral valve replacement for a patient with prosthetic ring endocarditis that developed late after undergoing undersized mitral annuloplasty (UMAP). A 58-year-old man had undergone left ventriculoplasty and UMAP with a 26-mm semi-rigid full ring for dilated cardiomyopathy and functional mitral regurgitation. The mitral valve had progressively stenosed and he developed prosthetic ring endocarditis 5 years after the operation. In the surgery, there were brownish fresh vegetations around the anterior mitral leaflet and the prosthetic ring. The mitral annulus was very small, even after removal of the infected ring prosthesis and debridement of the infected tissues. We implanted a 22-mm mechanical prosthesis in the supra-annular position using everting mattress sutures to prevent the valve leaflets from getting stuck by the thickened subannular tissue. Herein, we discuss the surgical procedures for a shrunken mitral annulus.展开更多
Background: Surgical method was introduced for enhancement of prosthetic valve insertion and overcoming difficulties ensourcing from prosthesis-patient mismatch. Methods: Twenty-two patients that underwent aortic valv...Background: Surgical method was introduced for enhancement of prosthetic valve insertion and overcoming difficulties ensourcing from prosthesis-patient mismatch. Methods: Twenty-two patients that underwent aortic valve replacement between January 2005 and July 2009 were included in this prospective study. In these patients, the insertion of prosthesis larger than the annulus diameter was attempted after the application of an external pressure that increased the transverse axis diameter of the aortic annulus. The postoperative results and complications were assessed. Results: This surgical method was performed on 22 patients (16 males, 6 females, mean age: 52.2 ± 15.8 years) during the valve replacement. In 12 patients (55%), replacement of proper sized aortic valve compliant to their surface area was accomplished, while the insertion of a proper valve could not be achieved in 10 (45%) of the patients. No perioperative mortality or complications related to the procedure were reported. Conclusion: Increasing the transverse diameter of aortic valve may not only facilitate the insertion of a prosthetic valve but also aid in overcoming prosthesis-patient mismatch. Further studies on larger series are necessary to document the actual effectively and precise selection criteria for application of this method.展开更多
Objective To investigate surgical technique and clinical outcomes of reconstruction of annulus and intervalvular fibrous body during valve replacements. Methods Fifty-nine patients underwent reconstruction of annulus ...Objective To investigate surgical technique and clinical outcomes of reconstruction of annulus and intervalvular fibrous body during valve replacements. Methods Fifty-nine patients underwent reconstruction of annulus or intervalvular fibrous body during valve replacement. Indications for operation were small展开更多
Annulus fibrosus(AF)repair remains a challenge because of its limited self-healing ability.Endogenous repair strategies combining scaffolds and growth factors show great promise in AF repair.Although the unique and be...Annulus fibrosus(AF)repair remains a challenge because of its limited self-healing ability.Endogenous repair strategies combining scaffolds and growth factors show great promise in AF repair.Although the unique and beneficial characteristics of decellularized extracellular matrix(ECM)in tissue repair have been demonstrated,the poor mechanical property of ECM hydrogels largely hinders their applications in tissue regeneration.In the present study,we combined polyethylene glycol diacrylate(PEGDA)and decellularized annulus fibrosus matrix(DAFM)to develop an injectable,photocurable hydrogel for AF repair.We found that the addition of PEGDA markedly improved the mechanical strength of DAFM hydrogels while maintaining their porous structure.Transforming growth factor-β1(TGF-β1)was further incorporated into PEGDA/DAFM hydrogels,and it could be continuously released from the hydrogel.The in vitro experiments showed that TGF-β1 facilitated the migration of AF cells.Furthermore,PEGDA/DAFM/TGF-β1 hydrogels supported the adhesion,proliferation,and increased ECM production of AF cells.In vivo repair performance of the hydrogels was assessed using a rat AF defect model.The results showed that the implantation of PEGDA/DAFM/TGF-β1 hydrogels effectively sealed the AF defect,prevented nucleus pulposus atrophy,retained disc height,and partially restored the biomechanical properties of disc.In addition,the implanted hydrogel was infiltrated by cells resembling AF cells and well integrated with adjacent AF tissue.In summary,findings from this study indicate that TGF-β1-supplemented DAFM hydrogels hold promise for AF repair.展开更多
The theoretical analysis of the mixed convective Buongiorno nanofluid flow in an inclined annular microchannel with convectively heated walls subjected to the effects of nonlinear thermal radiation,exponential heat so...The theoretical analysis of the mixed convective Buongiorno nanofluid flow in an inclined annular microchannel with convectively heated walls subjected to the effects of nonlinear thermal radiation,exponential heat source(EHS),thermal dependent heat source(THS)is carried out.The description of the Buongiorno nanofluid is implemented to analyze the Brownian diffusion and thermo-migration mechanisms.The general boundary conditions for the velocity,thermal,and nanoparticle volume fraction(NVF)are considered.Numerical solutions for fully developed governing equations are obtained using bvp5c solver and verified with FEM.The optimization of heat transport rates is made by using the Box-Behnken designbased response surface method.It is found that the Lorentz force and the inclination angle of the annulus significantly affect the rheological characteristics of the nanofluid.Nanoparticles increase thermal energy in the system through Brownian diffusion and thermophoresis,resulting in increased temperature field.Internal heat sources would serve as an important tool for modulating the thermal field in microchannel,as they are directly associated.At low-level values of the thermal Biot number,the exponential heat source,and the thermal radiation parameter,it is possible to attain the maximum Nusselt number on both walls of the annulus.展开更多
Low back pain is one of the most serious public health problems worldwide and the major clinical manifestation of intervertebral disc degeneration(IVDD).The key pathological change during IVDD is dysfunction of the an...Low back pain is one of the most serious public health problems worldwide and the major clinical manifestation of intervertebral disc degeneration(IVDD).The key pathological change during IVDD is dysfunction of the annulus fibrosus(AF).However,due to the lack of an in-depth understanding of AF biology,the methods to reconstruct the AF are very limited.In this study,the mice AF cell atlas were decoded by single-cell RNA sequencing to provide a guide for AF reconstruction.The results first identify a new population of AF cells,fibrochondrocyte-like AF cells,which synthesize both collagen Ⅰ and collagen Ⅱ and are potential functional cells for AF reconstruction.According to the dual features of the AF extracellular matrix,a composite hydrogel based on the acylation of methacrylated silk fibroin with methacrylated hyaluronic acid was produced.To obtain the ability to stimulate differentiation,the composite hydrogels were combined with a fibrochondrocyte-inducing supplement.Finally,reconstruction of the AF defects,by the novel AF stem cell-loaded composite hydrogel,could be observed,its amount of chondroid matrices recovered to 31.7% of AF aera which is significantly higher than that in other control groups.In summary,this study decodes the AF cell atlas,based on which a novel strategy for AF reconstruction is proposed.展开更多
A genuine neurotic condition is experienced when some blood constituents accumulate on the wall of the artery get withdrew from the wall, again join the circulatory system and coagulation occur. Role of copper nanopar...A genuine neurotic condition is experienced when some blood constituents accumulate on the wall of the artery get withdrew from the wall, again join the circulatory system and coagulation occur. Role of copper nanoparticles and inclined magnetic field on the peristaltic flow of a nanofluid in an annular region of inclined annulus is investigated.We represent the clot model by considering the small artery as an annulus whose outer tube has a wave of sinusoidal nature and inner tube has a clot on its walls. Lubrication approach is used to simplify the problem. Close form solutions are determined for temperature and velocity profile. Impact of related parameters on pressure rise, pressure gradient,velocity and streamlines are interpreted graphically. Comparison among the pure blood and copper blood is presented and analyzed. One main finding of the considered analysis is that the inclusion of copper nanoparticles enlarges the amplitude of the velocity. Therefore, the considered study plays a dominant role in biomedical applications.展开更多
Coiled tubing(CT)drilling technology offers significant advantages in terms of cost and efficiency for exploitations of unconventional oil and gas resources.However,the development of CT drilling technol-ogy is restri...Coiled tubing(CT)drilling technology offers significant advantages in terms of cost and efficiency for exploitations of unconventional oil and gas resources.However,the development of CT drilling technol-ogy is restricted by cuttings accumulation in the wellbore due to non-rotation of the drill string and limited circulating capacity.Cuttings cleaning becomes more difficult with the wall resistance of pipe-wellbore annulus on the cutting transport.Accurate description of particle transport process in the pipe-wellbore annulus is,therefore,important for improving the wellbore cleanliness.In this study,high-speed cam-era is used to record and analyze the settling process of particles in the transparent annulus filled with power-law fluids.A total of 540 tests were carried out,involving dimensionless diameters of 0.10-0.95 and particle Reynolds Numbers of 0.01-12.97,revealing the effect of the dimensionless diameter and particle Reynolds number on the annulus wall effect,and the wall factor model with an average relative error of2.75%was established.In addition,a dimensionless parameter,Archimedes number,independent of the settling velocity,was introduced to establish an explicit model of the settling velocity of spherical particles in the vertical annulus,with the average relative error of 7.89%.Finally,a calculation example was provided to show how to use the explicit model of settling velocity in annulus.The results of this study are expected to provide guidance for field engineers to improve the wellbore cleanliness of coiled tubing drilling.展开更多
Continuing our study of spectral triples on quantum domains,we look at unbounded invariant and covariant derivations in the quantum annulus.In particular,we investigate whether such derivations can be implemented by o...Continuing our study of spectral triples on quantum domains,we look at unbounded invariant and covariant derivations in the quantum annulus.In particular,we investigate whether such derivations can be implemented by operators with compact parametrices,a necessary condition in the definition of a spectral triple.展开更多
This paper is devoted to studying Bergman spaces A_(ω_(1,2))^(p)(M)(1<p<∞)induced by regular-weightω_(1,2) on annulus M.We characterize the function f in L_(ω1,2)^(1)(M)for which the induced Hankel operator ...This paper is devoted to studying Bergman spaces A_(ω_(1,2))^(p)(M)(1<p<∞)induced by regular-weightω_(1,2) on annulus M.We characterize the function f in L_(ω1,2)^(1)(M)for which the induced Hankel operator H_(f) is bounded(or compact)from A_(ω1,2)^(p)(M)to Lqω1,2(M)with 1<p,q<∞.展开更多
基金supported by a grant from National Natural Sciences Foundation of China (No.30700841)
文摘In order to investigate the apoptotic pathway of rabbit annulus fibrosus(AF) cells induced by mechanical overload,an experimental air-pressure model was established in this study to pressurize the rabbit AF cells in vitro.Cells were randomly divided into five groups in which the cells were exposed to a continuous pressure of 1.1 MPa for different lengths of time(0,5,12,24 and 36 h).The cell proliferation and apoptosis were detected by cell counting kit-8(CCK-8) assay and flow cytometry;the alterations in mitochondrial membrane potential were measured by fluorescence microscopy and fluorescence spectrophotometer;the activities of caspase-8 and 9 were determined by spectrophotometry.The results showed that after the cells were subjected to the pressure for 24 or 36 h,the cell proliferation was inhibited;the ratio of cell apoptosis was increased;the mitochondrial membrane potential was decreased;the activity of caspase-9 was enhanced;no activity changes were observed in caspase-8.The results suggested that treatment with a pressure of 1.1 MPa for more than 24 h can lead to the proliferation inhibition and the apoptosis of rabbit AF cells in vitro,and the mitochondrial-dependent pathway is implicated in the pressure-induced AF cell apoptosis.
基金This study was supported by the National Natural Science Foundation of China (No.81260287).
文摘Improving the closure effect of surgical suture for repair of annulus fibrosus defects remains an unsolved problem.A new type of porcine fibrin glue was reported for the repair of annulus fibrous defects in sheep models in this study.Continuous axial loading test showed that this glue could effectively improve the closure effect of surgical suture for annulus fibrous defect.Magnetic resonance imaging (MRI) of the lumbar spine confirmed that,compared with nonfibrin glue treated intervertebral discs,it contributed to preservation of the nucleus pulposus and maintained the physiological hydration of the intervertebral discs.Moreover,histomorphology evaluation showed that the porcine fibrin glue could partially reverse degeneration of the injured intervertebral discs.Taken together,porcine fibrin glue can effectively enhance the closure effect of surgical suture on annulus fibrosus,improve the repair effect and slow down the degeneration of the intervertebral disc,and provide a potential therapeutic strategy for degenerative intervertebral disc disease.
文摘The present work relates to a numerical investigation of double diffusive mixed convection around a horizontal annulus with a finned inner cylinder.The solutal and thermal buoyancy forces are sustained by maintaining the inner and outer cylinders at uniform temperatures and concentrations.Buoyancy effects are also considered,with the Boussinesq approximation.The forced convection effect is induced by the outer cylinder rotating with an angular velocity(ω)in an anti-clockwise direction.The studies are made for various combinations of dimensionless numbers;buoyancy ratio number(N),Lewis number(Le),Richardson number(Ri)and Grashof number(Gr).The isotherms,isoconcentrations and streamlines as well as both average and local Nusselt and Sherwood numbers were studied.A finite volume scheme is adopted to solve the transport equations for continuity,momentum,energy and mass transfer.The results indicate that the use of fins on the inner cylinder with outer cylinder rotation,significantly improves the heat and mass transfer in the annulus.
文摘The convective heat transfer of hybrid nanoliquids within a concentric annulus has wide engineering applications such as chemical industries, solar collectors, gas turbines, heat exchangers, nuclear reactors, and electronic component cooling due to their high heat transport rate. Hence, in this study, the characteristics of the heat transport mechanism in an annulus filled with the Ag-MgO/H_2O hybrid nanoliquid under the influence of quadratic thermal radiation and quadratic convection are analyzed. The nonuniform heat source/sink and induced magnetic field mechanisms are used to govern the basic equations concerning the transport of the composite nanoliquid. The dependency of the Nusselt number on the effective parameters(thermal radiation, nonlinear convection,and temperature-dependent heat source/sink parameter) is examined through sensitivity analyses based on the response surface methodology(RSM) and the face-centered central composite design(CCD). The heat transport of the composite nanoliquid for the spacerelated heat source/sink is observed to be higher than that for the temperature-related heat source/sink. The mechanisms of quadratic convection and quadratic thermal radiation are favorable for the momentum of the nanoliquid. The heat transport rate is more sensitive towards quadratic thermal radiation.
文摘In this study, integral operational methods are used to investigate the thermally induced transverse vibration of a thin elliptic annulus plate with elastic supports at both radial boundaries.The axisymmetric temperature distribution is determined by the heat conduction differential equation and its corresponding boundary conditions by employing a unified integral transform technique by use of Mathieu functions and modified Mathieu functions. The solution of thermally induced vibration of the plate with both ends encased with elastic supports is obtained by employing an integral transform for double Laplace differential equation. The thermal moment is derived on the basis of temperature distribution, and its stresses are obtained based on resultant bending moments per unit width. The numerical calculations of the distributions of the transient temperature and its associated stress distributions are shown in the figures.
基金supported by the Major Program of the National Natural Science Foundation of China(Grant No.51239005)the National Natural Science Foundation of China(Grant No.11404147)+3 种基金the Natural Science Foundation of Jiangsu Province,China(Grant No.BK20140519)the China Postdoctoral Science Foundation(Grant No.2015M571672)the Research Fund for Advanced Talents of Jiangsu University,China(Grant No.11JDG118)the Training Project of Young Backbone Teachers of Jiangsu University,China
文摘We report an acoustic focusing lens composed of two-layer annuluses made of metal cylinders in air. We find that the cylindrical waves can be focused into a perfect point without diffraction in the centre of the annuluses, which arises from the Mie-resonance modes in the annuluses. The focusing frequencies are related to the size of the inner annulus, and the focusing effect can be applied to the annuluses with different shapes and incident positions. Interesting applications of the focusing lens in the acoustic beam splitter and directional transmitter with energy enhancement are further discussed.
基金the Strategic Cooperation Technology Projects of CNPC and CUPB(ZLZX2020-03)China Scholarship Council(201906440166)for their financial supportfinancial support provided by the Natural Sciences and Engineering Research Council of Canada(NSERC RGPIN-2016-04647 KURU)。
文摘Hole cleaning is a complex process as there are many variables affecting cuttings removal(e.g.drilling fluid type,density,flow rate and rheological properties,cuttings size,drill pipe rotation speed).With the increasing number of drilling small diameter wells(e.g.coiled tubing drilling applications,ultra-deep wells drilled for exploitations of unconventional oil and gas resources),the wall resistance of the micro annulus also emerges as one of the most critical factors affecting the cuttings accumulation in wellbore.The eccentricity of drill pipes commonly observed during the drilling process of ultra-deep well and coiled tubing well makes the wall resistance effect on the cuttings transport even more prominent.Understanding the wall resistance effect on the particle settling behavior in eccentric annuli is,therefore,crucial for hydraulic design of efficient cuttings transport operations in these wells.In this study,a total of 196 sets of particle settling experiments were carried out to investigate the particle settling behavior in eccentric annuli filled with power-law fluids.The test matrix included the eccentricity ranges of 0-0.80,the dimensionless diameter ranges of 0.13-0.75 and the particle Reynolds number ranges of 0.09-32.34.A high-speed camera was used to record the particle settling process and determine the influences of the eccentricity,the dimensionless diameter,the fluid rheological properties,and the solid particle characteristics on the wall factor and the particle settling velocity.The functional relationship among the dimensionless diameter,the particle Reynolds number,and the wall factor was determined by using the method of controlling variables.An eccentric annulus wall factor model with average relative error of 5.16%was established.Moreover,by introducing Archimedes number,an explicit model of particle settling velocity in the eccentric annulus with average relative error of 10.17%was established.A sample calculation of particle settling velocity was provided to show the application of the explicit model.Results of this study can be used as a guideline by field engineers to improve hydraulic design of cuttings transport operations in concentric and eccentric annuli.
基金This research project is supported by Naresuan University fund.
文摘Background:The surgical outcomes of tetralogy of Fallot(TOF)have evolved dramatically and have resulted in lower mortality rate.Currently,the many cardiac centers have a trend to early single-stage complete repair more than a staged repair.However,the patients who have an early primary repair were required transannular patch augmentation of a pulmonary valve frequently.This effect has been developed a chronic pulmonary insufficiency may lead to right ventricular dilation,dysfunction.In this era,the aim of treatment of TOF is attempted to preserve pulmonary valve annulus for prevent right ventricular dysfunction in the future.The systemic to pulmonary artery shunt is a palliative procedure or known as staged repair for symptomatic patients with TOF.The modified Blalock-Taussig shunt(mBTS)is the most useful systemic to pulmonary shunt and perform as an initial procedure before complete repair.The mBTS can provide increase pulmonary blood flow as well as improve oxygenation and also promote pulmonary artery(PA)growth.However,the effect of this procedure to promote growth of a pulmonary valve annulus is still debate.Objectives:To compare a growth of pulmonary valve annulus between after staged repair and primary repair in patients with TOF(without pulmonary atresia).Methods:A retrospective case-control study,review of patients with TOF underwent total repair at our hospitals from January 2005 and December 2017 was performed,a total number of 112 patients underwent TOF repair.Twenty-nine patients(26%)underwent a staged repair(mBTS group)and 83(74%)underwent total repair only or primary repair(PR group).We evaluated diameter of pulmonary valve annulus by using echocardiography at the time of first diagnosis and before complete repair on both groups.Results:The age of diagnosis of mBTS group were younger than PR group(p=0.011).Therefore,pulmonary valve annuls were smaller in mBTS group.(Z-score,−2.93±1.42 vs.−1.89±0.97;p=0.001).However,the growth potential of pulmonary valve annulus was increase more than PR group significantly(Z-score,−1.46±1.02 vs.−2.11±1.19;p=0.009)Even though a patent ductus arteriosus was found commonly in PR group(p=0.018).Conclusions:Our results suggest the systemic to pulmonary shunt or mBTS can promote growth of pulmonary valve annulus in patients with TOF.
文摘The interaction of transient fully developed natural convection flow with thermal radiation inside a vertical annulus is analyzed both analytically and numerically. The Rosseland approximation is used to describe the radiative heat flux in the energy equation. The mathematical model capturing the present physical situation is highly non-linear due to the presence of radiation effect. The solution of transient model is obtained by implicit finite difference method. To check accuracy of the numerical solution, steady state solution for energy and momentum equations are derived analytically using perturbation series method. Skin-friction and Nusselt number at the outer surface of inner cylinder as well as inner surface of the outer cylinder are obtained. Selected sets of graphical results illustrating the effects of various controlling parameters involved in the problem on flow formation are discussed.
文摘Mitral Annular Calcification (MAC) is a degenerative process involving the fibrous ring of the mitral valve. Caseous Calcification of Mitral Annulus (CCMA) is a rare variant of MAC. This condition is benign and usually needs no treatment. This is a case report of a 67-year-old woman with non-specific symptoms in whom a cardiac tumor was suspected by transthoracic Echocardiography. The use of multi-modality imaging strategy with transesophageal Echocardiography and cardiac MR scanning revealed however the diagnosis of CCMA and spared the patient an unnecessary operation.
文摘We report a case of supra-annular mitral valve replacement for a patient with prosthetic ring endocarditis that developed late after undergoing undersized mitral annuloplasty (UMAP). A 58-year-old man had undergone left ventriculoplasty and UMAP with a 26-mm semi-rigid full ring for dilated cardiomyopathy and functional mitral regurgitation. The mitral valve had progressively stenosed and he developed prosthetic ring endocarditis 5 years after the operation. In the surgery, there were brownish fresh vegetations around the anterior mitral leaflet and the prosthetic ring. The mitral annulus was very small, even after removal of the infected ring prosthesis and debridement of the infected tissues. We implanted a 22-mm mechanical prosthesis in the supra-annular position using everting mattress sutures to prevent the valve leaflets from getting stuck by the thickened subannular tissue. Herein, we discuss the surgical procedures for a shrunken mitral annulus.
文摘Background: Surgical method was introduced for enhancement of prosthetic valve insertion and overcoming difficulties ensourcing from prosthesis-patient mismatch. Methods: Twenty-two patients that underwent aortic valve replacement between January 2005 and July 2009 were included in this prospective study. In these patients, the insertion of prosthesis larger than the annulus diameter was attempted after the application of an external pressure that increased the transverse axis diameter of the aortic annulus. The postoperative results and complications were assessed. Results: This surgical method was performed on 22 patients (16 males, 6 females, mean age: 52.2 ± 15.8 years) during the valve replacement. In 12 patients (55%), replacement of proper sized aortic valve compliant to their surface area was accomplished, while the insertion of a proper valve could not be achieved in 10 (45%) of the patients. No perioperative mortality or complications related to the procedure were reported. Conclusion: Increasing the transverse diameter of aortic valve may not only facilitate the insertion of a prosthetic valve but also aid in overcoming prosthesis-patient mismatch. Further studies on larger series are necessary to document the actual effectively and precise selection criteria for application of this method.
文摘Objective To investigate surgical technique and clinical outcomes of reconstruction of annulus and intervalvular fibrous body during valve replacements. Methods Fifty-nine patients underwent reconstruction of annulus or intervalvular fibrous body during valve replacement. Indications for operation were small
基金the funding provided for this study by the National Natural Science Foundation of China(81925027,32130059,31872748,32171350,32101103)Natural Science Foundation of Jiangsu Province(BK20200199)+1 种基金China Postdoctoral Science Foundation(2021M702412)the Priority Academic Program Development of Jiangsu Higher Education Institutions.
文摘Annulus fibrosus(AF)repair remains a challenge because of its limited self-healing ability.Endogenous repair strategies combining scaffolds and growth factors show great promise in AF repair.Although the unique and beneficial characteristics of decellularized extracellular matrix(ECM)in tissue repair have been demonstrated,the poor mechanical property of ECM hydrogels largely hinders their applications in tissue regeneration.In the present study,we combined polyethylene glycol diacrylate(PEGDA)and decellularized annulus fibrosus matrix(DAFM)to develop an injectable,photocurable hydrogel for AF repair.We found that the addition of PEGDA markedly improved the mechanical strength of DAFM hydrogels while maintaining their porous structure.Transforming growth factor-β1(TGF-β1)was further incorporated into PEGDA/DAFM hydrogels,and it could be continuously released from the hydrogel.The in vitro experiments showed that TGF-β1 facilitated the migration of AF cells.Furthermore,PEGDA/DAFM/TGF-β1 hydrogels supported the adhesion,proliferation,and increased ECM production of AF cells.In vivo repair performance of the hydrogels was assessed using a rat AF defect model.The results showed that the implantation of PEGDA/DAFM/TGF-β1 hydrogels effectively sealed the AF defect,prevented nucleus pulposus atrophy,retained disc height,and partially restored the biomechanical properties of disc.In addition,the implanted hydrogel was infiltrated by cells resembling AF cells and well integrated with adjacent AF tissue.In summary,findings from this study indicate that TGF-β1-supplemented DAFM hydrogels hold promise for AF repair.
基金This study was supported by Internal Research Support Programs(Program No.IRSPG202104),Wenzhou-Kean University,China.
文摘The theoretical analysis of the mixed convective Buongiorno nanofluid flow in an inclined annular microchannel with convectively heated walls subjected to the effects of nonlinear thermal radiation,exponential heat source(EHS),thermal dependent heat source(THS)is carried out.The description of the Buongiorno nanofluid is implemented to analyze the Brownian diffusion and thermo-migration mechanisms.The general boundary conditions for the velocity,thermal,and nanoparticle volume fraction(NVF)are considered.Numerical solutions for fully developed governing equations are obtained using bvp5c solver and verified with FEM.The optimization of heat transport rates is made by using the Box-Behnken designbased response surface method.It is found that the Lorentz force and the inclination angle of the annulus significantly affect the rheological characteristics of the nanofluid.Nanoparticles increase thermal energy in the system through Brownian diffusion and thermophoresis,resulting in increased temperature field.Internal heat sources would serve as an important tool for modulating the thermal field in microchannel,as they are directly associated.At low-level values of the thermal Biot number,the exponential heat source,and the thermal radiation parameter,it is possible to attain the maximum Nusselt number on both walls of the annulus.
基金the financial support of the following funds for our study:The State Key Program of National Natural Science Foundation of China(Grant nos.81730065 to Z.L.,82130070 to L.Y.)Projects of International Cooperation and Exchanges of National Natural Science Foundation of China(Grant nos.82020108019 to Z.L.).
文摘Low back pain is one of the most serious public health problems worldwide and the major clinical manifestation of intervertebral disc degeneration(IVDD).The key pathological change during IVDD is dysfunction of the annulus fibrosus(AF).However,due to the lack of an in-depth understanding of AF biology,the methods to reconstruct the AF are very limited.In this study,the mice AF cell atlas were decoded by single-cell RNA sequencing to provide a guide for AF reconstruction.The results first identify a new population of AF cells,fibrochondrocyte-like AF cells,which synthesize both collagen Ⅰ and collagen Ⅱ and are potential functional cells for AF reconstruction.According to the dual features of the AF extracellular matrix,a composite hydrogel based on the acylation of methacrylated silk fibroin with methacrylated hyaluronic acid was produced.To obtain the ability to stimulate differentiation,the composite hydrogels were combined with a fibrochondrocyte-inducing supplement.Finally,reconstruction of the AF defects,by the novel AF stem cell-loaded composite hydrogel,could be observed,its amount of chondroid matrices recovered to 31.7% of AF aera which is significantly higher than that in other control groups.In summary,this study decodes the AF cell atlas,based on which a novel strategy for AF reconstruction is proposed.
文摘A genuine neurotic condition is experienced when some blood constituents accumulate on the wall of the artery get withdrew from the wall, again join the circulatory system and coagulation occur. Role of copper nanoparticles and inclined magnetic field on the peristaltic flow of a nanofluid in an annular region of inclined annulus is investigated.We represent the clot model by considering the small artery as an annulus whose outer tube has a wave of sinusoidal nature and inner tube has a clot on its walls. Lubrication approach is used to simplify the problem. Close form solutions are determined for temperature and velocity profile. Impact of related parameters on pressure rise, pressure gradient,velocity and streamlines are interpreted graphically. Comparison among the pure blood and copper blood is presented and analyzed. One main finding of the considered analysis is that the inclusion of copper nanoparticles enlarges the amplitude of the velocity. Therefore, the considered study plays a dominant role in biomedical applications.
基金express their appreciation to National Key Research and Development Program(2019YFA0708300)the Strategic Coop-eration Technology Projects of CNPC and CUPB(ZIZX2020-03)China Scholarship Council(201906440166)for their financial support.
文摘Coiled tubing(CT)drilling technology offers significant advantages in terms of cost and efficiency for exploitations of unconventional oil and gas resources.However,the development of CT drilling technol-ogy is restricted by cuttings accumulation in the wellbore due to non-rotation of the drill string and limited circulating capacity.Cuttings cleaning becomes more difficult with the wall resistance of pipe-wellbore annulus on the cutting transport.Accurate description of particle transport process in the pipe-wellbore annulus is,therefore,important for improving the wellbore cleanliness.In this study,high-speed cam-era is used to record and analyze the settling process of particles in the transparent annulus filled with power-law fluids.A total of 540 tests were carried out,involving dimensionless diameters of 0.10-0.95 and particle Reynolds Numbers of 0.01-12.97,revealing the effect of the dimensionless diameter and particle Reynolds number on the annulus wall effect,and the wall factor model with an average relative error of2.75%was established.In addition,a dimensionless parameter,Archimedes number,independent of the settling velocity,was introduced to establish an explicit model of the settling velocity of spherical particles in the vertical annulus,with the average relative error of 7.89%.Finally,a calculation example was provided to show how to use the explicit model of settling velocity in annulus.The results of this study are expected to provide guidance for field engineers to improve the wellbore cleanliness of coiled tubing drilling.
文摘Continuing our study of spectral triples on quantum domains,we look at unbounded invariant and covariant derivations in the quantum annulus.In particular,we investigate whether such derivations can be implemented by operators with compact parametrices,a necessary condition in the definition of a spectral triple.
基金Supported by NNSF of China(Grant Nos.11971125,11471084)。
文摘This paper is devoted to studying Bergman spaces A_(ω_(1,2))^(p)(M)(1<p<∞)induced by regular-weightω_(1,2) on annulus M.We characterize the function f in L_(ω1,2)^(1)(M)for which the induced Hankel operator H_(f) is bounded(or compact)from A_(ω1,2)^(p)(M)to Lqω1,2(M)with 1<p,q<∞.
