Rapid progress in tissue engineering research in past decades has opened up vast possibilities to tackle the challenges of generating tissues or organs that mimic native structures. The success of tissue engineered co...Rapid progress in tissue engineering research in past decades has opened up vast possibilities to tackle the challenges of generating tissues or organs that mimic native structures. The success of tissue engineered constructs largely depends on the incorporation of a stable vascular network that eventually anastomoses with the host vasculature to support the various biological functions of embedded cells. In recent years, significant progress has been achieved with respect to extrusion, laser, micro-molding, and electrospinning-based techniques that allow the fabrication of any geometry in a layer-by-layer fashion. Moreover, decellularized matrix, self-assembled structures, and cell sheets have been explored to replace the biopolymers needed for scaffold fabrication. While the techniques have evolved to create specific tissues or organs with outstanding geometric precision, formation of interconnected, functional, and perfused vascular networks remains a challenge. This article briefly reviews recent progress in 3D fabrication approaches used to fabricate vascular networks with incorporated cells, angiogenic factors, proteins, and/or peptides. The influence of the fabricated network on blood vessel formation, and the various features, merits, and shortcomings of the various fabrication techniques are discussed and summarized.展开更多
Bioinks are formulations of biomaterials and living cells, sometimes with growth factors or other biomolecules, while extrusion bioprinting is an emerging technique to apply or deposit these bioinks or biomaterial sol...Bioinks are formulations of biomaterials and living cells, sometimes with growth factors or other biomolecules, while extrusion bioprinting is an emerging technique to apply or deposit these bioinks or biomaterial solutions to create three-dimensional (3D) constructs with architectures and mechanical/biological properties that mimic those of native human tissue or organs. Printed constructs have found wide applications in tissue engineering for repairing or treating tissue/organ injuries, as well as in vitro tissue modelling for testing or validating newly developed therapeutics and vaccines prior to their use in humans. Successful printing of constructs and their subsequent applications rely on the properties of the formulated bioinks, including the rheological, mechanical, and biological properties, as well as the printing process. This article critically reviews the latest developments in bioinks and biomaterial solutions for extrusion bioprinting, focusing on bioink synthesis and characterization, as well as the influence of bioink properties on the printing process. Key issues and challenges are also discussed along with recommendations for future research.展开更多
The maximum demand of power utilization is increasing exponentially from base load to peak load in day to day life.This power demand may be either industrial usage or household applications.To meet this high maximum p...The maximum demand of power utilization is increasing exponentially from base load to peak load in day to day life.This power demand may be either industrial usage or household applications.To meet this high maximum power demand by the consumer,one of the options is the integration of renewable energy resources with conventional power generation methods.In the present scenario,wind energy system is one of the methods to generate power in connection with the conventional power systems.When the load on the conventional grid system increases,various bus voltages of the system tend to decrease,causing serious voltage drop or voltage instability within the system.In view of this,identification of weak buses within the system has become necessary.This paper presents the line indices method to identify these weak buses,so that some corrective action may be taken to compensate for this drop in voltage.An attempt has been made to compensate these drops in voltages by integration of renewable energy systems.The wind energy system at one of the bus in the test system is integrated and the performance of the system is verified by calculating the power flow(PF)using the power system analysis tool box(PSAT)and line indices of the integrated test system.The PF and load flow results are used to calculate line indices for the IEEE-14 bus test system which is simulated on PSAT.展开更多
Conservation agriculture(CA)is considered as a suitable technique for soil erosion control,productivity enhancement,and improved economic benefits.To investigate these issues,an experiment was conducted under rainfed ...Conservation agriculture(CA)is considered as a suitable technique for soil erosion control,productivity enhancement,and improved economic benefits.To investigate these issues,an experiment was conducted under rainfed conditions using grass vegetation strip(VS)with minimum tillage,organic amendments and weed mulch during June 2007-October 2011 at Dehradun,Uttarakhand in the Indian Himalayan region.Results showed that the mean wheat equivalent yield was47%higher in the plots under with CA compared with conventional agriculture in a maize-wheat crop rotation.Mean runoff coefficients and soil loss with CA plots were45%less and54%less than conventional agriculture plots.On average,after the harvest of maize,soil moisture conservation up to 90 cm soil depth for wheat crop was 108%higher under CA than conventional agriculture plots.The net return from the plots with CA was 85%higher,and when expressed net return per tonne of soil loss,it was four and half times higher than conventional practice.Results demonstrate that the suitable CA practice(a grass strip of Palmarosa with applied organic amendments(farmyard manure,vermicompost and poultry manure)along with weed mulching under conservation tillage)enhances system productivity,reduces runoff,soil loss and conserve soil moisture.&2015 International Research and Training Center on Erosion and Sedimentation and China Water and Power Press.Production and Hosting by Elsevier B.V.This is an open access article under the CC BY-NC-ND license(http://creativecommons.org/licenses/by-nc-nd/4.0/).展开更多
This paper deals with the study of transient waves in a homogeneous isotropic,solid halfspace with a permeating substance in the context of the theory of generalized elasto-thermodiffusion.The halfspace is assumed to ...This paper deals with the study of transient waves in a homogeneous isotropic,solid halfspace with a permeating substance in the context of the theory of generalized elasto-thermodiffusion.The halfspace is assumed to be disturbed due to mechanical loads acting on its boundary.The model comprising of basic governing differential equations and boundary conditions has been solved by employing Laplace transform technique.Noting that the second sound effects are short lived,the small time approximations of solution for various physical quantities have been obtained and the results are discussed on the possible wave fronts.In case of continuous and periodic loads acting at the boundary,the displacement is found to be continuous at each wave front while it is discontinuous in case of impulsive load.The temperature and concentration fields are found to be discontinuous at all the wave fronts.The displacement,temperature change and concentration deviation due to impulsive,continuous and periodic mechanical loads have also been evaluated in the physical domain at all times by employing numerical inversion technique of integral transform.The computer simulated numerical results have been presented graphically in respect of displacement,temperature change and concentration deviation for brass.A significant effect of mass diffusion has been observed on the behaviour of mechanical and thermal waves.展开更多
基金supported by the Natural Sciences and Engineering Research Council of Canada [NSERC RGPIN-2014-05648]
文摘Rapid progress in tissue engineering research in past decades has opened up vast possibilities to tackle the challenges of generating tissues or organs that mimic native structures. The success of tissue engineered constructs largely depends on the incorporation of a stable vascular network that eventually anastomoses with the host vasculature to support the various biological functions of embedded cells. In recent years, significant progress has been achieved with respect to extrusion, laser, micro-molding, and electrospinning-based techniques that allow the fabrication of any geometry in a layer-by-layer fashion. Moreover, decellularized matrix, self-assembled structures, and cell sheets have been explored to replace the biopolymers needed for scaffold fabrication. While the techniques have evolved to create specific tissues or organs with outstanding geometric precision, formation of interconnected, functional, and perfused vascular networks remains a challenge. This article briefly reviews recent progress in 3D fabrication approaches used to fabricate vascular networks with incorporated cells, angiogenic factors, proteins, and/or peptides. The influence of the fabricated network on blood vessel formation, and the various features, merits, and shortcomings of the various fabrication techniques are discussed and summarized.
文摘Bioinks are formulations of biomaterials and living cells, sometimes with growth factors or other biomolecules, while extrusion bioprinting is an emerging technique to apply or deposit these bioinks or biomaterial solutions to create three-dimensional (3D) constructs with architectures and mechanical/biological properties that mimic those of native human tissue or organs. Printed constructs have found wide applications in tissue engineering for repairing or treating tissue/organ injuries, as well as in vitro tissue modelling for testing or validating newly developed therapeutics and vaccines prior to their use in humans. Successful printing of constructs and their subsequent applications rely on the properties of the formulated bioinks, including the rheological, mechanical, and biological properties, as well as the printing process. This article critically reviews the latest developments in bioinks and biomaterial solutions for extrusion bioprinting, focusing on bioink synthesis and characterization, as well as the influence of bioink properties on the printing process. Key issues and challenges are also discussed along with recommendations for future research.
文摘The maximum demand of power utilization is increasing exponentially from base load to peak load in day to day life.This power demand may be either industrial usage or household applications.To meet this high maximum power demand by the consumer,one of the options is the integration of renewable energy resources with conventional power generation methods.In the present scenario,wind energy system is one of the methods to generate power in connection with the conventional power systems.When the load on the conventional grid system increases,various bus voltages of the system tend to decrease,causing serious voltage drop or voltage instability within the system.In view of this,identification of weak buses within the system has become necessary.This paper presents the line indices method to identify these weak buses,so that some corrective action may be taken to compensate for this drop in voltage.An attempt has been made to compensate these drops in voltages by integration of renewable energy systems.The wind energy system at one of the bus in the test system is integrated and the performance of the system is verified by calculating the power flow(PF)using the power system analysis tool box(PSAT)and line indices of the integrated test system.The PF and load flow results are used to calculate line indices for the IEEE-14 bus test system which is simulated on PSAT.
文摘Conservation agriculture(CA)is considered as a suitable technique for soil erosion control,productivity enhancement,and improved economic benefits.To investigate these issues,an experiment was conducted under rainfed conditions using grass vegetation strip(VS)with minimum tillage,organic amendments and weed mulch during June 2007-October 2011 at Dehradun,Uttarakhand in the Indian Himalayan region.Results showed that the mean wheat equivalent yield was47%higher in the plots under with CA compared with conventional agriculture in a maize-wheat crop rotation.Mean runoff coefficients and soil loss with CA plots were45%less and54%less than conventional agriculture plots.On average,after the harvest of maize,soil moisture conservation up to 90 cm soil depth for wheat crop was 108%higher under CA than conventional agriculture plots.The net return from the plots with CA was 85%higher,and when expressed net return per tonne of soil loss,it was four and half times higher than conventional practice.Results demonstrate that the suitable CA practice(a grass strip of Palmarosa with applied organic amendments(farmyard manure,vermicompost and poultry manure)along with weed mulching under conservation tillage)enhances system productivity,reduces runoff,soil loss and conserve soil moisture.&2015 International Research and Training Center on Erosion and Sedimentation and China Water and Power Press.Production and Hosting by Elsevier B.V.This is an open access article under the CC BY-NC-ND license(http://creativecommons.org/licenses/by-nc-nd/4.0/).
文摘This paper deals with the study of transient waves in a homogeneous isotropic,solid halfspace with a permeating substance in the context of the theory of generalized elasto-thermodiffusion.The halfspace is assumed to be disturbed due to mechanical loads acting on its boundary.The model comprising of basic governing differential equations and boundary conditions has been solved by employing Laplace transform technique.Noting that the second sound effects are short lived,the small time approximations of solution for various physical quantities have been obtained and the results are discussed on the possible wave fronts.In case of continuous and periodic loads acting at the boundary,the displacement is found to be continuous at each wave front while it is discontinuous in case of impulsive load.The temperature and concentration fields are found to be discontinuous at all the wave fronts.The displacement,temperature change and concentration deviation due to impulsive,continuous and periodic mechanical loads have also been evaluated in the physical domain at all times by employing numerical inversion technique of integral transform.The computer simulated numerical results have been presented graphically in respect of displacement,temperature change and concentration deviation for brass.A significant effect of mass diffusion has been observed on the behaviour of mechanical and thermal waves.
