Sample records for engineered arterial constructs

  1. Construction and histological analysis of a 3D human arterial wall model containing vasa vasorum using a layer-by-layer technique.

    PubMed

    Shima, Fumiaki; Narita, Hirokazu; Hiura, Ayami; Shimoda, Hiroshi; Akashi, Mitsuru

    2017-03-01

    There is considerable global demand for three-dimensional (3D) functional tissues which mimic our native organs and tissues for use as in vitro drug screening systems and in regenerative medicine. In particular, there has been an increasing number of patients who suffer from arterial diseases such as arteriosclerosis. As such, in vitro 3D arterial wall models that can evaluate the effects of novel medicines and a novel artificial graft for the treatment are required. In our previous study, we reported the rapid construction of 3D tissues by employing a layer-by-layer (LbL) technique and revealed their potential applications in the pharmaceutical fields and tissue engineering. In this study, we successfully constructed a 3D arterial wall model containing vasa vasorum by employing a LbL technique for the first time. The cells were coated with extracellular matrix nanofilms and seeded into a culture insert using a cell accumulation method. This model had a three-layered hierarchical structure: a fibroblast layer, a smooth muscle layer, and an endothelial layer, which resembled the native arterial wall. Our method could introduce vasa vasorum into a fibroblast layer in vitro and the 3D arterial wall model showed barrier function which was evaluated by immunostaining and transendothelial electrical resistance measurement. Furthermore, electron microscopy observations revealed that the vasa vasorum was composed of single-layered endothelial cells, and the endothelial tubes were surrounded by the basal lamina, which are known to promote maturation and stabilization in native blood capillaries. These models should be useful for tissue engineering, regenerative medicine, and pharmaceutical applications. © 2016 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 105A: 814-823, 2017. © 2016 Wiley Periodicals, Inc.

  2. Cryogenic thermal diode heat pipes

    NASA Technical Reports Server (NTRS)

    Alario, J.

    1979-01-01

    The development of spiral artery cryogenic thermal diode heat pipes was continued. Ethane was the working fluid and stainless steel the heat pipe material in all cases. The major tasks included: (1) building a liquid blockage (blocking orifice) thermal diode suitable for the HEPP space flight experiment; (2) building a liquid trap thermal diode engineering model; (3) retesting the original liquid blockage engineering model, and (4) investigating the startup dynamics of artery cryogenic thermal diodes. An experimental investigation was also conducted into the wetting characteristics of ethane/stainless steel systems using a specially constructed chamber that permitted in situ observations.

  3. Spatial differences of cellular origins and in vivo hypoxia modify contractile properties of pulmonary artery smooth muscle cells: lessons for arterial tissue engineering.

    PubMed

    Hall, S M; Soueid, A; Smith, T; Brown, R A; Haworth, S G; Mudera, V

    2007-01-01

    Tissue engineering of functional arteries is challenging. Within the pulmonary artery wall, smooth muscle cells (PASMCs) have site-specific developmental and functional phenotypes, reflecting differing contractile roles. The force generated by PASMCs isolated from the inner 25% and outer 50% of the media of intrapulmonary elastic arteries from five normal and eight chronically hypoxic (hypertensive) 14 day-old piglets was quantified in a three-dimensional (3D) collagen construct, using a culture force monitor. Outer medial PASMCs from normal piglets exerted more force (528 +/- 50 dynes) than those of hypoxic piglets (177 +/- 42 dynes; p < 0.01). Force generation by inner medial PASMCs from normal and hypoxic piglets was similar (349 +/- 35 and 239 +/- 60 dynes). In response to agonist (thromboxane) stimulation, all PASMCs from normal and hypoxic piglets contracted, but the increase in force generated by outer and inner hypoxic PASMCs (ranges 13-72 and 14-56 dynes) was less than by normal PASMCs (ranges 27-154 and 34-159 dynes, respectively; p < 0.05 for both). All hypoxic PASMCs were unresponsive to antagonist (sodium nitroprusside) stimulation, all normal PASMCs relaxed (range - 87 to - 494 dynes). Myosin heavy chain expression by both hypoxic PASMC phenotypes was less than normal (p < 0.05 for both), as was the activity of focal adhesion kinase, regulating contraction, in hypoxic inner PASMCs (p < 0.01). Chronic hypoxia resulted in the development of abnormal PASMC phenotypes, which in collagen constructs exhibited a reduction in contractile force and reactivity to agonists. Characterization of the mechanical response of spatially distinct cells and modification of their behaviour by hypoxia is critical for successful tissue engineering of major blood vessels.

  4. Construction of biocompatible porous tissue scaffold from the decellularized umbilical artery.

    PubMed

    Xin, Yi; Wu, Guanghui; Wu, Man; Zhang, Xiaoxia; Velot, Emilie; Decot, Véronique; Cui, Wei; Huang, Yimin; Stoltz, Jean-Francois; Du, Jie; Li, Na

    2015-01-01

    The scaffolds prepared from the tissue decellularization conserve the porous 3-D structure and provide an optimal matrix for the tissue regeneration. Since decade, the enzymatic digestion, chemical reagent treatment and mechanical actions such as eversion and abrasion have been used to remove the cells from the intact matrix. In this study, we optimized an enzymatic method to decellularize the umbilical artery to construct a 3-D porous scaffold which is suitable for the culture of mesenchymal stem cells (MSCs). The scaffold maintained the interconnected porous structure. It remained the similar high water content 95.3 ± 1% compared to 94.9 ± 0.6% in the intact umbilical artery (p>0.05). The decellularization process decreased the stress from 0.24 ± 0.05 mPa to 0.15 ± 0.06 mPa (p<0.05). However the decellularization did not change the strain of the artery (45 ± 15% vs. 53 ± 10%, p>0.05). When the scaffold was transplanted to the subcutaneous tissue in the wild type mice, there were less T cells appeared in the surrounding tissue which meant the decreased the immunogenicity by decellularization. This scaffold also supported the adhesion and proliferation of the MSCs. In this study, we constructed a biological compatible porous scaffold from the decellularized umbilical artery which may provide a suitable scaffold for cell-matrix interaction studies and for tissue engineering.

  5. The Public Sector Construction Industry: Analysis of Single-Project Partnering

    DTIC Science & Technology

    1992-12-22

    thesis advisor, Dr. Fred Moavenzadeh for his guidance and encouragement. Colonel Larry S. Bonine , U.S. Army (Retired) and the members of his Partnering...PROJECT (CkG) ENGINEERS MANAGERS PR::JECT PARINERING TEAM Figure 4-4. Central Artery/Tunnel Organizational Chart. 116 MR. Larry Bonine an employee of the...joint venture team. MR. Bonine is an ex-Army Colonel and was the Corps District Engineer in Mobile, Alabama who oversaw the Oliver Lock and Dam and

  6. Cell Sheet-Based Tissue Engineering for Organizing Anisotropic Tissue Constructs Produced Using Microfabricated Thermoresponsive Substrates.

    PubMed

    Takahashi, Hironobu; Okano, Teruo

    2015-11-18

    In some native tissues, appropriate microstructures, including orientation of the cell/extracellular matrix, provide specific mechanical and biological functions. For example, skeletal muscle is made of oriented myofibers that is responsible for the mechanical function. Native artery and myocardial tissues are organized three-dimensionally by stacking sheet-like tissues of aligned cells. Therefore, to construct any kind of complex tissue, the microstructures of cells such as myotubes, smooth muscle cells, and cardiomyocytes also need to be organized three-dimensionally just as in the native tissues of the body. Cell sheet-based tissue engineering allows the production of scaffold-free engineered tissues through a layer-by-layer construction technique. Recently, using microfabricated thermoresponsive substrates, aligned cells are being harvested as single continuous cell sheets. The cell sheets act as anisotropic tissue units to build three-dimensional tissue constructs with the appropriate anisotropy. This cell sheet-based technology is straightforward and has the potential to engineer a wide variety of complex tissues. In addition, due to the scaffold-free cell-dense environment, the physical and biological cell-cell interactions of these cell sheet constructs exhibit unique cell behaviors. These advantages will provide important clues to enable the production of well-organized tissues that closely mimic the structure and function of native tissues, required for the future of tissue engineering. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  7. Biomechanical Comparison of Glutaraldehyde-Crosslinked Gelatin Fibrinogen Electrospun Scaffolds to Porcine Coronary Arteries

    PubMed Central

    Tamimi, E.; Ardila, D. C.; Haskett, D. G.; Doetschman, T.; Slepian, M. J.; Kellar, R. S.; Vande Geest, J. P.

    2016-01-01

    Cardiovascular disease (CVD) is the leading cause of death for Americans. As coronary artery bypass graft surgery (CABG) remains a mainstay of therapy for CVD and native vein grafts are limited by issues of supply and lifespan, an effective readily available tissue-engineered vascular graft (TEVG) for use in CABG would provide drastic improvements in patient care. Biomechanical mismatch between vascular grafts and native vasculature has been shown to be the major cause of graft failure, and therefore, there is need for compliance-matched biocompatible TEVGs for clinical implantation. The current study investigates the biaxial mechanical characterization of acellular electrospun glutaraldehyde (GLUT) vapor-crosslinked gelatin/fibrinogen cylindrical constructs, using a custom-made microbiaxial optomechanical device (MOD). Constructs crosslinked for 2, 8, and 24 hrs are compared to mechanically characterized porcine left anterior descending coronary (LADC) artery. The mechanical response data were used for constitutive modeling using a modified Fung strain energy equation. The results showed that constructs crosslinked for 2 and 8 hrs exhibited circumferential and axial tangential moduli (ATM) similar to that of the LADC. Furthermore, the 8-hrs experimental group was the only one to compliance-match the LADC, with compliance values of 0.0006±0.00018 mm Hg−1 and 0.00071±0.00027 mm Hg−1, respectively. The results of this study show the feasibility of meeting mechanical specifications expected of native arteries through manipulating GLUT vapor crosslinking time. The comprehensive mechanical characterization of cylindrical biopolymer constructs in this study is an important first step to successfully develop a biopolymer compliance-matched TEVG. PMID:26501189

  8. Use of magnetic micro-cantilevers to study the dynamics of 3D engineered smooth muscle constructs

    NASA Astrophysics Data System (ADS)

    Liu, Alan; Zhao, Ruogang; Copeland, Craig; Chen, Christopher; Reich, Daniel

    2013-03-01

    The normal and pathological response of arterial tissue to mechanical stimulus sheds important light on such conditions as atherosclerosis and hypertension. While most previous methods of determining the biomechanical properties of arteries have relied on excised tissue, we have devised a system that enables the growth and in situ application of forces to arrays of stable suspended microtissues consisting of arterial smooth muscle cells (SMCs). Briefly, this magnetic microtissue tester system consists of arrays of pairs of elastomeric magnetically actuated micro-cantilevers between which SMC-infused 3D collagen gels self-assemble and remodel into aligned microtissue constructs. These devices allow us to simultaneously apply force and track stress-strain relationships of multiple microtissues per substrate. We have studied the dilatory capacity and subsequent response of the tissues and find that the resulting stress-strain curves show viscoelastic behavior as well as a linear dynamic recovery. These results provide a foundation for elucidating the mechanical behavior of this novel model system as well as further experiments that simulate pathological conditions. Supported in part by NIH grant HL090747.

  9. The mechanical properties of infrainguinal vascular bypass grafts: their role in influencing patency.

    PubMed

    Sarkar, S; Salacinski, H J; Hamilton, G; Seifalian, A M

    2006-06-01

    When autologous vein is unavailable, prosthetic graft materials, particularly expanded polytetrafluoroethylene are used for peripheral arterial revascularisation. Poor long term patency of prosthetic materials is due to distal anastomotic intimal hyperplasia. Intimal hyperplasia is directly linked to shear stress abnormalities at the vessel wall. Compliance and calibre mismatch between native vessel and graft, as well as anastomotic line stress concentration contribute towards unnatural wall shear stress. High porosity reduces graft compliance by causing fibrovascular infiltration, whereas low porosity discourages the development of an endothelial lining and hence effective antithrombogenicity. Therefore, consideration of mechanical properties is necessary in graft development. Current research into synthetic vascular grafts concentrates on simulating the mechanical properties of native arteries and tissue engineering aims to construct a new biological arterial conduit.

  10. Engineering anastomosis between living capillary networks and endothelial cell-lined microfluidic channels.

    PubMed

    Wang, Xiaolin; Phan, Duc T T; Sobrino, Agua; George, Steven C; Hughes, Christopher C W; Lee, Abraham P

    2016-01-21

    This paper reports a method for generating an intact and perfusable microvascular network that connects to microfluidic channels without appreciable leakage. This platform incorporates different stages of vascular development including vasculogenesis, endothelial cell (EC) lining, sprouting angiogenesis, and anastomosis in sequential order. After formation of a capillary network inside the tissue chamber via vasculogenesis, the adjacent microfluidic channels are lined with a monolayer of ECs, which then serve as the high-pressure input ("artery") and low pressure output ("vein") conduits. To promote a tight interconnection between the artery/vein and the capillary network, sprouting angiogenesis is induced, which promotes anastomosis of the vasculature inside the tissue chamber with the EC lining along the microfluidic channels. Flow of fluorescent microparticles confirms the perfusability of the lumenized microvascular network, and minimal leakage of 70 kDa FITC-dextran confirms physiologic tightness of the EC junctions and completeness of the interconnections between artery/vein and the capillary network. This versatile device design and its robust construction methodology establish a physiological transport model of interconnected perfused vessels from artery to vascularized tissue to vein. The system has utility in a wide range of organ-on-a-chip applications as it enables the physiological vascular interconnection of multiple on-chip tissue constructs that can serve as disease models for drug screening.

  11. Hair Follicle-Derived Smooth Muscle Cells and Small Intestinal Submucosa for Engineering Mechanically Robust and Vasoreactive Vascular Media

    PubMed Central

    Peng, Hao-Fan; Liu, Jin Yu

    2011-01-01

    Our laboratory recently reported a new source of smooth muscle cells (SMCs) derived from hair follicle (HF) mesenchymal stem cells. HF-SMCs demonstrated high proliferation and clonogenic potential as well as contractile function. In this study, we aimed at engineering the vascular media using HF-SMCs and a natural biomaterial, namely small intestinal submucosa (SIS). Engineering functional vascular constructs required application of mechanical force, resulting in actin reorganization and cellular alignment. In turn, cell alignment was necessary for development of receptor- and nonreceptor-mediated contractility as soon as 24 h after cell seeding. Within 2 weeks in culture, the cells migrated into SIS and secreted collagen and elastin, the two major extracellular matrix components of the vessel wall. At 2 weeks, vascular reactivity increased significantly up to three- to fivefold and mechanical properties were similar to those of native ovine arteries. Taken together, our data demonstrate that the combination of HF-SMCs with SIS resulted in mechanically strong, biologically functional vascular media with potential for arterial implantation. PMID:21083418

  12. Computationally Optimizing the Compliance of a Biopolymer Based Tissue Engineered Vascular Graft

    PubMed Central

    Harrison, Scott; Tamimi, Ehab; Uhlorn, Josh; Leach, Tim; Vande Geest, Jonathan P.

    2016-01-01

    Coronary heart disease is a leading cause of death among Americans for which coronary artery bypass graft (CABG) surgery is a standard surgical treatment. The success of CABG surgery is impaired by a compliance mismatch between vascular grafts and native vessels. Tissue engineered vascular grafts (TEVGs) have the potential to be compliance matched and thereby reduce the risk of graft failure. Glutaraldehyde (GLUT) vapor-crosslinked gelatin/fibrinogen constructs were fabricated and mechanically tested in a previous study by our research group at 2, 8, and 24 hrs of GLUT vapor exposure. The current study details a computational method that was developed to predict the material properties of our constructs for crosslinking times between 2 and 24 hrs by interpolating the 2, 8, and 24 hrs crosslinking time data. matlab and abaqus were used to determine the optimal combination of fabrication parameters to produce a compliance matched construct. The validity of the method was tested by creating a 16-hr crosslinked construct of 130 μm thickness and comparing its compliance to that predicted by the optimization algorithm. The predicted compliance of the 16-hr construct was 0.00059 mm Hg−1 while the experimentally determined compliance was 0.00065 mm Hg−1, a relative difference of 9.2%. Prior data in our laboratory has shown the compliance of the left anterior descending porcine coronary (LADC) artery to be 0.00071 ± 0.0003 mm Hg−1. Our optimization algorithm predicts that a 258-μm-thick construct that is GLUT vapor crosslinked for 8.1 hrs would match LADC compliance. This result is consistent with our previous work demonstrating that an 8-hr GLUT vapor crosslinked construct produces a compliance that is not significantly different from a porcine coronary LADC. PMID:26593773

  13. Engineering Factor Xa Inhibitor with Multiple Platelet-Binding Sites Facilitates its Platelet Targeting

    NASA Astrophysics Data System (ADS)

    Zhu, Yuanjun; Li, Ruyi; Lin, Yuan; Shui, Mengyang; Liu, Xiaoyan; Chen, Huan; Wang, Yinye

    2016-07-01

    Targeted delivery of antithrombotic drugs centralizes the effects in the thrombosis site and reduces the hemorrhage side effects in uninjured vessels. We have recently reported that the platelet-targeting factor Xa (FXa) inhibitors, constructed by engineering one Arg-Gly-Asp (RGD) motif into Ancylostoma caninum anticoagulant peptide 5 (AcAP5), can reduce the risk of systemic bleeding than non-targeted AcAP5 in mouse arterial injury model. Increasing the number of platelet-binding sites of FXa inhibitors may facilitate their adhesion to activated platelets, and further lower the bleeding risks. For this purpose, we introduced three RGD motifs into AcAP5 to generate a variant NR4 containing three platelet-binding sites. NR4 reserved its inherent anti-FXa activity. Protein-protein docking showed that all three RGD motifs were capable of binding to platelet receptor αIIbβ3. Molecular dynamics simulation demonstrated that NR4 has more opportunities to interact with αIIbβ3 than single-RGD-containing NR3. Flow cytometry analysis and rat arterial thrombosis model further confirmed that NR4 possesses enhanced platelet targeting activity. Moreover, NR4-treated mice showed a trend toward less tail bleeding time than NR3-treated mice in carotid artery endothelium injury model. Therefore, our data suggest that engineering multiple binding sites in one recombinant protein is a useful tool to improve its platelet-targeting efficiency.

  14. Proteomic Profiling of Tissue-Engineered Blood Vessel Walls Constructed by Adipose-Derived Stem Cells

    PubMed Central

    Wang, Chen; Guo, Fangfang; Zhou, Heng; Zhang, Yun; Xiao, Zhigang

    2013-01-01

    Adipose-derived stem cells (ASCs) can differentiate into smooth muscle cells and have been engineered into elastic small diameter blood vessel walls in vitro. However, the mechanisms involved in the development of three-dimensional (3D) vascular tissue remain poorly understood. The present study analyzed protein expression profiles of engineered blood vessel walls constructed by human ASCs using methods of two-dimensional gel electrophoresis (2DE) and mass spectrometry (MS). These results were compared to normal arterial walls. A total of 1701±15 and 1265±26 protein spots from normal and engineered blood vessel wall extractions were detected by 2DE, respectively. A total of 20 spots with at least 2.0-fold changes in expression were identified, and 38 differently expressed proteins were identified by 2D electrophoresis and ion trap MS. These proteins were classified into seven functional categories: cellular organization, energy, signaling pathway, enzyme, anchored protein, cell apoptosis/defense, and others. These results demonstrated that 2DE, followed by ion trap MS, could be successfully utilized to characterize the proteome of vascular tissue, including tissue-engineered vessels. The method could also be employed to achieve a better understanding of differentiated smooth muscle protein expression in vitro. These results provide a basis for comparative studies of protein expression in vascular smooth muscles of different origin and could provide a better understanding of the mechanisms of action needed for constructing blood vessels that exhibit properties consistent with normal blood vessels. PMID:22963350

  15. Proteomic profiling of tissue-engineered blood vessel walls constructed by adipose-derived stem cells.

    PubMed

    Wang, Chen; Guo, Fangfang; Zhou, Heng; Zhang, Yun; Xiao, Zhigang; Cui, Lei

    2013-02-01

    Adipose-derived stem cells (ASCs) can differentiate into smooth muscle cells and have been engineered into elastic small diameter blood vessel walls in vitro. However, the mechanisms involved in the development of three-dimensional (3D) vascular tissue remain poorly understood. The present study analyzed protein expression profiles of engineered blood vessel walls constructed by human ASCs using methods of two-dimensional gel electrophoresis (2DE) and mass spectrometry (MS). These results were compared to normal arterial walls. A total of 1701±15 and 1265±26 protein spots from normal and engineered blood vessel wall extractions were detected by 2DE, respectively. A total of 20 spots with at least 2.0-fold changes in expression were identified, and 38 differently expressed proteins were identified by 2D electrophoresis and ion trap MS. These proteins were classified into seven functional categories: cellular organization, energy, signaling pathway, enzyme, anchored protein, cell apoptosis/defense, and others. These results demonstrated that 2DE, followed by ion trap MS, could be successfully utilized to characterize the proteome of vascular tissue, including tissue-engineered vessels. The method could also be employed to achieve a better understanding of differentiated smooth muscle protein expression in vitro. These results provide a basis for comparative studies of protein expression in vascular smooth muscles of different origin and could provide a better understanding of the mechanisms of action needed for constructing blood vessels that exhibit properties consistent with normal blood vessels.

  16. Laser direct writing of combinatorial libraries of idealized cellular constructs: Biomedical applications

    NASA Astrophysics Data System (ADS)

    Schiele, Nathan R.; Koppes, Ryan A.; Corr, David T.; Ellison, Karen S.; Thompson, Deanna M.; Ligon, Lee A.; Lippert, Thomas K. M.; Chrisey, Douglas B.

    2009-03-01

    The ability to control cell placement and to produce idealized cellular constructs is essential for understanding and controlling intercellular processes and ultimately for producing engineered tissue replacements. We have utilized a novel intra-cavity variable aperture excimer laser operated at 193 nm to reproducibly direct write mammalian cells with micrometer resolution to form a combinatorial array of idealized cellular constructs. We deposited patterns of human dermal fibroblasts, mouse myoblasts, rat neural stem cells, human breast cancer cells, and bovine pulmonary artery endothelial cells to study aspects of collagen network formation, breast cancer progression, and neural stem cell proliferation, respectively. Mammalian cells were deposited by matrix assisted pulsed laser evaporation direct write from ribbons comprised of a UV transparent quartz coated with either a thin layer of extracellular matrix or triazene as a dynamic release layer using CAD/CAM control. We demonstrate that through optical imaging and incorporation of a machine vision algorithm, specific cells on the ribbon can be laser deposited in spatial coherence with respect to geometrical arrays and existing cells on the receiving substrate. Having the ability to direct write cells into idealized cellular constructs can help to answer many biomedical questions and advance tissue engineering and cancer research.

  17. In vitro fabrication of functional three-dimensional tissues with perfusable blood vessels

    PubMed Central

    Sekine, Hidekazu; Shimizu, Tatsuya; Sakaguchi, Katsuhisa; Dobashi, Izumi; Wada, Masanori; Yamato, Masayuki; Kobayashi, Eiji; Umezu, Mitsuo; Okano, Teruo

    2013-01-01

    In vitro fabrication of functional vascularized three-dimensional tissues has been a long-standing objective in the field of tissue engineering. Here we report a technique to engineer cardiac tissues with perfusable blood vessels in vitro. Using resected tissue with a connectable artery and vein as a vascular bed, we overlay triple-layer cardiac cell sheets produced from coculture with endothelial cells, and support the tissue construct with media perfused in a bioreactor. We show that endothelial cells connect to capillaries in the vascular bed and form tubular lumens, creating in vitro perfusable blood vessels in the cardiac cell sheets. Thicker engineered tissues can be produced in vitro by overlaying additional triple-layer cell sheets. The vascularized cardiac tissues beat and can be transplanted with blood vessel anastomoses. This technique may create new opportunities for in vitro tissue engineering and has potential therapeutic applications. PMID:23360990

  18. Creation of a Large Adipose Tissue Construct in Humans Using a Tissue-engineering Chamber: A Step Forward in the Clinical Application of Soft Tissue Engineering.

    PubMed

    Morrison, Wayne A; Marre, Diego; Grinsell, Damien; Batty, Andrew; Trost, Nicholas; O'Connor, Andrea J

    2016-04-01

    Tissue engineering is currently exploring new and exciting avenues for the repair of soft tissue and organ defects. Adipose tissue engineering using the tissue engineering chamber (TEC) model has yielded promising results in animals; however, to date, there have been no reports on the use of this device in humans. Five female post mastectomy patients ranging from 35 to 49years old were recruited and a pedicled thoracodorsal artery perforator fat flap ranging from 6 to 50ml was harvested, transposed onto the chest wall and covered by an acrylic perforated dome-shaped chamber ranging from 140 to 350cm(3). Magnetic resonance evaluation was performed at three and six months after chamber implantation. Chambers were removed at six months and samples were obtained for histological analysis. In one patient, newly formed tissue to a volume of 210ml was generated inside the chamber. One patient was unable to complete the trial and the other three failed to develop significant enlargement of the original fat flap, which, at the time of chamber explantation, was encased in a thick fibrous capsule. Our study provides evidence that generation of large well-vascularized tissue engineered constructs using the TEC is feasible in humans. Copyright © 2016 The Authors. Published by Elsevier B.V. All rights reserved.

  19. Engineering of arteries in vitro

    PubMed Central

    Huang, Angela H.; Niklason, Laura E.

    2014-01-01

    This review will focus on two elements that are essential for functional arterial regeneration in vitro: the mechanical environment and the bioreactors used for tissue growth. The importance of the mechanical environment to embryological development, vascular functionality, and vascular graft regeneration will be discussed. Bioreactors generate mechanical stimuli to simulate the biomechanical environment of the arterial system. This system has been used to reconstruct arterial grafts with appropriate mechanical strength for implantation by controlling the chemical and mechanical environments in which the grafts are grown. Bioreactors are powerful tools to study the effect of mechanical stimuli on extracellular matrix (ECM) architecture and the mechanical properties of engineered vessels. Hence biomimetic systems enable us to optimize chemo-biomechanical culture conditions to regenerate engineered vessels with physiological properties similar to those of native arterial vessels. In addition, this review will introduce and examine various approaches and techniques that have been used to engineer biologically-based vascular grafts, including collagen-based grafts, fibrin-gel grafts, cell sheet engineering, biodegradable polymers, and decellularization of native vessels. PMID:24399290

  20. ARTVAL user guide : user guide for the ARTerial eVALuation computational engine.

    DOT National Transportation Integrated Search

    2015-06-01

    This document provides guidance on the use of the ARTVAL (Arterial Evaluation) computational : engine. The engine implements the Quick Estimation Method for Urban Streets (QEM-US) : described in Highway Capacity Manual (HCM2010) as the core computati...

  1. Tissue-Engineered Fibrin-Based Heart Valve with a Tubular Leaflet Design

    PubMed Central

    Weber, Miriam; Heta, Eriona; Moreira, Ricardo; Gesche, Valentine N.; Schermer, Thomas; Frese, Julia

    2014-01-01

    The general approach in heart valve tissue engineering is to mimic the shape of the native valve in the attempt to recreate the natural haemodynamics. In this article, we report the fabrication of the first tissue-engineered heart valve (TEHV) based on a tubular leaflet design, where the function of the leaflets of semilunar heart valves is performed by a simple tubular construct sutured along a circumferential line at the root and at three single points at the sinotubular junction. The tubular design is a recent development in pericardial (nonviable) bioprostheses, which has attracted interest because of the simplicity of the construction and the reliability of the implantation technique. Here we push the potential of the concept further from the fabrication and material point of view to realize the tube-in-tube valve: an autologous, living HV with remodelling and growing capability, physiological haemocompatibility, simple to construct and fast to implant. We developed two different fabrication/conditioning procedures and produced fibrin-based constructs embedding cells from the ovine umbilical cord artery according to the two different approaches. Tissue formation was confirmed by histology and immunohistology. The design of the tube-in-tube foresees the possibility of using a textile coscaffold (here demonstrated with a warp-knitted mesh) to achieve enhanced mechanical properties in vision of implantation in the aortic position. The tube-in-tube represents an attractive alternative to the conventional design of TEHVs aiming at reproducing the valvular geometry. PMID:23829551

  2. Tubular inverse opal scaffolds for biomimetic vessels

    NASA Astrophysics Data System (ADS)

    Zhao, Ze; Wang, Jie; Lu, Jie; Yu, Yunru; Fu, Fanfan; Wang, Huan; Liu, Yuxiao; Zhao, Yuanjin; Gu, Zhongze

    2016-07-01

    There is a clinical need for tissue-engineered blood vessels that can be used to replace or bypass damaged arteries. The success of such grafts depends strongly on their ability to mimic native arteries; however, currently available artificial vessels are restricted by their complex processing, controversial integrity, or uncontrollable cell location and orientation. Here, we present new tubular scaffolds with specific surface microstructures for structural vessel mimicry. The tubular scaffolds are fabricated by rotationally expanding three-dimensional tubular inverse opals that are replicated from colloidal crystal templates in capillaries. Because of the ordered porous structure of the inverse opals, the expanded tubular scaffolds are imparted with circumferentially oriented elliptical pattern microstructures on their surfaces. It is demonstrated that these tailored tubular scaffolds can effectively make endothelial cells to form an integrated hollow tubular structure on their inner surface and induce smooth muscle cells to form a circumferential orientation on their outer surface. These features of our tubular scaffolds make them highly promising for the construction of biomimetic blood vessels.There is a clinical need for tissue-engineered blood vessels that can be used to replace or bypass damaged arteries. The success of such grafts depends strongly on their ability to mimic native arteries; however, currently available artificial vessels are restricted by their complex processing, controversial integrity, or uncontrollable cell location and orientation. Here, we present new tubular scaffolds with specific surface microstructures for structural vessel mimicry. The tubular scaffolds are fabricated by rotationally expanding three-dimensional tubular inverse opals that are replicated from colloidal crystal templates in capillaries. Because of the ordered porous structure of the inverse opals, the expanded tubular scaffolds are imparted with circumferentially oriented elliptical pattern microstructures on their surfaces. It is demonstrated that these tailored tubular scaffolds can effectively make endothelial cells to form an integrated hollow tubular structure on their inner surface and induce smooth muscle cells to form a circumferential orientation on their outer surface. These features of our tubular scaffolds make them highly promising for the construction of biomimetic blood vessels. Electronic supplementary information (ESI) available. See DOI: 10.1039/c6nr03173k

  3. Advances in vascular tissue engineering.

    PubMed

    Thomas, Anita C; Campbell, Gordon R; Campbell, Julie H

    2003-01-01

    Coronary and peripheral artery bypass grafting is commonly used to relieve the symptoms of vascular deficiencies, but the supply of autologous artery or vein may not be sufficient or suitable for multiple bypass or repeat procedures, necessitating the use of other materials. Synthetic materials are suitable for large bore arteries but often thrombose when used in smaller arteries. Suitable replacement grafts must have appropriate characteristics, including resistance to infection, low immunogenicity and good biocompatability and thromboresistance, with appropriate mechanical and physiological properties and cheap and fast manufacture. Current avenues of graft development include coating synthetic grafts with either biological chemicals or cells with anticoagulatory properties. Matrix templates or acellular tubes of extracellular matrix (such as collagen) may be coated or infiltrated with cultured cells. Once placed into the artery, these grafts may become colonised by host cells and gain many of the properties of normal artery. "Tissue-engineered blood vessels" may also be formed from layers of human vascular cells grown in culture. These engineered vessels have many of the characteristics of arteries formed in vivo. "Artificial arteries" may be also be derived from peritoneal granulation tissue in body "bioreactors" by adapting the body's natural wound healing response to produce a hollow tube.

  4. The stentable in vitro artery: an instrumented platform for endovascular device development and optimization.

    PubMed

    Antoine, Elizabeth E; Cornat, François P; Barakat, Abdul I

    2016-12-01

    Although vascular disease is a leading cause of mortality, in vitro tools for controlled, quantitative studies of vascular biological processes in an environment that reflects physiological complexity remain limited. We developed a novel in vitro artery that exhibits a number of unique features distinguishing it from tissue-engineered or organ-on-a-chip constructs, most notably that it allows deployment of endovascular devices including stents, quantitative real-time tracking of cellular responses and detailed measurement of flow velocity and lumenal shear stress using particle image velocimetry. The wall of the stentable in vitro artery consists of an annular collagen hydrogel containing smooth muscle cells (SMCs) and whose lumenal surface is lined with a monolayer of endothelial cells (ECs). The system has in vivo dimensions and physiological flow conditions and allows automated high-resolution live imaging of both SMCs and ECs. To demonstrate proof-of-concept, we imaged and quantified EC wound healing, SMC motility and altered shear stresses on the endothelium after deployment of a coronary stent. The stentable in vitro artery provides a unique platform suited for a broad array of research applications. Wide-scale adoption of this system promises to enhance our understanding of important biological events affecting endovascular device performance and to reduce dependence on animal studies. © 2016 The Author(s).

  5. Evaluation of engineering treatments and pedestrian and motorist behavior on major arterials in Washington State.

    DOT National Transportation Integrated Search

    2008-09-01

    This report examines pedestrian and motorist behavior on arterials in Washington State and determines how, if at all, these behaviors change when various engineering treatments are applied. The treatments that were examined included crosswalk marking...

  6. Quality of Construction Central Artery / Third Harbor Tunnel Federal Highway Administration Region 1

    DOT National Transportation Integrated Search

    1996-12-19

    The objective of this audit was to evaluate the Federal Highway : Administration's (FHWA) oversight of the Central Artery / Third Harbor Tunnel : Project's (Project) testing procedures to ensure construction was completed in : accordance with applica...

  7. Geo-Hazards and Mountain Road Development in Nepal: Understanding the Science-Policy-Governance Interface

    NASA Astrophysics Data System (ADS)

    Dugar, Sumit; Dahal, Vaskar

    2015-04-01

    The foothills of Nepalese Himalayas located in the neotectonic mountain environment are among some of the most unstable and geomorphologically dynamic landscapes in the world. Young fold mountains in this region are characterized by complex tectonics that influence the occurrence of earthquakes, while climatic processes such as intense orographic rainfall often dictate the occurrence of floods and landslides. Development of linear infrastructures, such as roads, in mountainous terrain characterized by high relief and orogeny is considerably challenging where the complexity of landscape in steep and irregular topography, difficult ground conditions and weak geology, presents engineers and planners with numerous difficulties to construct and maintain mountain roads. Whilst application of engineering geology, geomorphic interpretation of terrain in terms of physiography and hydrology, and identification of geo-hazards along the road corridor is critical for long term operation of mountain roads, low-cost arterial roads in the Himalayan foothills generally fail to incorporate standard road slope engineering structures. This research provides unique insights on policy and governance issues in developing mountainous countries such as Nepal, where achieving a sound balance between sustainability and affordability is a major challenge for road construction. Road development in Nepal is a complex issue where socio-economic and political factors influence the budget allocation for road construction in rural hilly areas. Moreover, most mountain roads are constructed without any geological or geo-technical site investigations due to rampant corruption and lack of adequate engineering supervision. Despite having good examples of rural road construction practices such as the Dharan-Dhankuta Road in Eastern Nepal where comprehensive terrain-evaluation methods and geo-technical surveys led to an improved understanding of road construction, learnings from this project have not informed other road development schemes in Nepal. Geomorphological surveys and robust geo-hazard assessments that factor the spatial and temporal dimensions of the seismic, fluvial and sediment hazards along the road corridor are critical for sustainable development of mountain roads. However, scientific and technical research studies seldom inform mountain road development primarily due to lack of co-ordination between the respective government agencies, access to journal papers in developing countries and unwillingness to adopt novel interventions in rural road construction practices. These challenges are further exacerbated by weak governance and lack of proper policy enforcement that often leads to construction of poorly engineered roads, thereby increasing the risk of rural infrastructural damage from geo-hazards. Though there exists a disconnect between the science-policy-governance interface where information on geo-hazards is neglected in mountain road development due to lack of scientific research and government apathy, there is an opportunity to spur dialogue and sensitize these issues via trans-disciplinary approaches on disaster risk management.

  8. Tubular inverse opal scaffolds for biomimetic vessels.

    PubMed

    Zhao, Ze; Wang, Jie; Lu, Jie; Yu, Yunru; Fu, Fanfan; Wang, Huan; Liu, Yuxiao; Zhao, Yuanjin; Gu, Zhongze

    2016-07-14

    There is a clinical need for tissue-engineered blood vessels that can be used to replace or bypass damaged arteries. The success of such grafts depends strongly on their ability to mimic native arteries; however, currently available artificial vessels are restricted by their complex processing, controversial integrity, or uncontrollable cell location and orientation. Here, we present new tubular scaffolds with specific surface microstructures for structural vessel mimicry. The tubular scaffolds are fabricated by rotationally expanding three-dimensional tubular inverse opals that are replicated from colloidal crystal templates in capillaries. Because of the ordered porous structure of the inverse opals, the expanded tubular scaffolds are imparted with circumferentially oriented elliptical pattern microstructures on their surfaces. It is demonstrated that these tailored tubular scaffolds can effectively make endothelial cells to form an integrated hollow tubular structure on their inner surface and induce smooth muscle cells to form a circumferential orientation on their outer surface. These features of our tubular scaffolds make them highly promising for the construction of biomimetic blood vessels.

  9. An animal model for instructing and the study of in situ arterial bypass.

    PubMed

    Saifi, J; Chang, B B; Paty, P S; Kaufman, J; Leather, R P; Shah, D M

    1990-11-01

    A canine model that used the cephalic vein to bypass from the brachial to the ulnar artery was designed for use in instructing and evaluating surgical technique needed for constructing an in situ arterial bypass. This model was used for instructing vascular residents in the in situ vein bypass technique. The use of this model enabled the resident to become more adept with the instruments for valve incision and construction of small vessel anastomosis. The improvement in the resident's operative technique was reflected by a decrease in the number of technical complications (missed valves, missed arteriovenous fistulas, poorly constructed anastomoses) and improved patency rate.

  10. Design and construction of driven pile foundations--lessons learned on the Central Artery/Tunnel project

    DOT National Transportation Integrated Search

    2006-06-01

    Five contracts from the Central Artery/Tunnel (CA/T) project in Boston, MA, were reviewed to document issues related to design and construction of driven pile foundations. Given the soft and compressible marine clays in the Boston area, driven pile f...

  11. Hydraulic Conductivity of Smooth Muscle Cell-Initiated Arterial Cocultures

    PubMed Central

    Mathura, Rishi A.; Russell-Puleri, Sparkle; Cancel, Limary M.; Tarbell, John M.

    2015-01-01

    The purpose of the study was to examine the effects of arterial coculture conditions on the transport properties of several in vitro endothelial cell (EC) – smooth muscle cell (SMC) – porous filter constructs in which SMC were grown to confluence first and then EC were inoculated. This order of culturing simulates the environment of a blood vessel wall after endothelial layer damage due to stenting, vascular grafting or other vascular wall insult. For all coculture configurations examined, we observed that hydraulic conductivity (Lp) values were significantly higher than predicted by a resistances-in-series (RIS) model accounting for the Lp of EC and SMC measured separately. The greatest increases were observed when EC were plated directly on top of a confluent SMC layer without an intervening filter, presumably mediated by direct EC – SMC contacts that were observed under confocal microscopy. The results are the opposite of a previous study that showed Lp was significantly reduced compared to an RIS model when EC were grown to confluency first. The physiological, pathophysiological and tissue engineering implications of these results are discussed. PMID:26265460

  12. Hydraulic Conductivity of Smooth Muscle Cell-Initiated Arterial Cocultures.

    PubMed

    Mathura, Rishi A; Russell-Puleri, Sparkle; Cancel, Limary M; Tarbell, John M

    2016-05-01

    The purpose of the study was to examine the effects of arterial coculture conditions on the transport properties of several in vitro endothelial cell (EC)-smooth muscle cell (SMC)-porous filter constructs in which SMC were grown to confluence first and then EC were inoculated. This order of culturing simulates the environment of a blood vessel wall after endothelial layer damage due to stenting, vascular grafting or other vascular wall insult. For all coculture configurations examined, we observed that hydraulic conductivity (L(p)) values were significantly higher than predicted by a resistances-in-series (RIS) model accounting for the L(p) of EC and SMC measured separately. The greatest increases were observed when EC were plated directly on top of a confluent SMC layer without an intervening filter, presumably mediated by direct EC-SMC contacts that were observed under confocal microscopy. The results are the opposite of a previous study that showed L(p) was significantly reduced compared to an RIS model when EC were grown to confluency first. The physiological, pathophysiological and tissue engineering implications of these results are discussed.

  13. [Introduction and advantage analysis of the stepwise method for the construction of vascular trees].

    PubMed

    Zhang, Yan; Xie, Haiwei; Zhu, Kai

    2010-08-01

    A new method for constructing the model of vascular trees was proposed in this paper. By use of this method, the arterial trees in good agreement with the actual structure could be grown. In this process, all vessels in the vascular tree were divided into two groups: the conveying vessels, and the delivering branches. And different branches could be built by different ways. Firstly, the distributing rules of conveying vessels were ascertained by use of measurement data, and then the conveying vessels were constructed in accordance to the statistical rule and optimization criterion. Lastly, delivering branches were modeled by constrained constructive optimization (CCO) on the conveying vessel-trees which had already been generated. In order to compare the CCO method and stepwise method proposed here, two 3D arterial trees of human tongue were grown with their vascular tree having a special structure. Based on the corrosion casts of real arterial tree of human tongue, the data about the two trees constructed by different methods were compared and analyzed, including the averaged segment diameters at respective levels, the distribution and the diameters of the branches of first level at respective directions. The results show that the vascular tree built by stepwise method is more similar to the true arterial of human tongue when compared against the tree built by CCO method.

  14. Heparin Stimulates Elastogenesis: Application to Silk-Based Vascular Grafts

    PubMed Central

    Baughman, Cassandra; Kaplan, David L.; Castellot, John J.

    2013-01-01

    With over 500,000 coronary artery bypass grafts (CABG) performed annually in the United States alone, there is a significant clinical need for a small diameter tissue engineered vascular graft. A principle goal in tissue engineering is to develop materials and growth conditions that encourage appropriate re-cellularization and extracellular matrix formation in vivo. A particular challenge in vascular tissue engineering results from the inability of adult cells to produce elastin, as its expression is developmentally limited. We investigated factors to stimulate elastogenesis in vitro, and found that heparin treatment of adult human vascular smooth muscle cells promoted the formation of elastic fibers. This effect was heparin-specific, and dependent on cell density and growth state. We then applied this information to a silk-based construct, and found that immobilized heparin showed essentially identical biological effects to that of soluble heparin. These findings indicate that heparinized vascular grafts may promote elastin formation and regulate restenosis, in addition to heparin’s well-established antithrombotic properties. Given the increase in elastin mRNA level and the increase in extracellular elastin present, our data suggests that there may be multiple levels of elastin regulation that are mediated by heparin treatment. PMID:21600981

  15. 48 CFR 1436.209 - Construction contracts with architect-engineer firms.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... with architect-engineer firms. 1436.209 Section 1436.209 Federal Acquisition Regulations System DEPARTMENT OF THE INTERIOR SPECIAL CATEGORIES OF CONTRACTING CONSTRUCTION AND ARCHITECT-ENGINEER CONTRACTS Special Aspects of Contracting for Construction 1436.209 Construction contracts with architect-engineer...

  16. 48 CFR 436.209 - Construction contracts with architect-engineer firms.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... with architect-engineer firms. 436.209 Section 436.209 Federal Acquisition Regulations System DEPARTMENT OF AGRICULTURE SPECIAL CATEGORIES OF CONTRACTING CONSTRUCTION AND ARCHITECT-ENGINEER CONTRACTS Special Aspects of Contracting for Construction 436.209 Construction contracts with architect-engineer...

  17. 48 CFR 1436.209 - Construction contracts with architect-engineer firms.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... with architect-engineer firms. 1436.209 Section 1436.209 Federal Acquisition Regulations System DEPARTMENT OF THE INTERIOR SPECIAL CATEGORIES OF CONTRACTING CONSTRUCTION AND ARCHITECT-ENGINEER CONTRACTS Special Aspects of Contracting for Construction 1436.209 Construction contracts with architect-engineer...

  18. 48 CFR 1436.209 - Construction contracts with architect-engineer firms.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... with architect-engineer firms. 1436.209 Section 1436.209 Federal Acquisition Regulations System DEPARTMENT OF THE INTERIOR SPECIAL CATEGORIES OF CONTRACTING CONSTRUCTION AND ARCHITECT-ENGINEER CONTRACTS Special Aspects of Contracting for Construction 1436.209 Construction contracts with architect-engineer...

  19. 48 CFR 436.209 - Construction contracts with architect-engineer firms.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... with architect-engineer firms. 436.209 Section 436.209 Federal Acquisition Regulations System DEPARTMENT OF AGRICULTURE SPECIAL CATEGORIES OF CONTRACTING CONSTRUCTION AND ARCHITECT-ENGINEER CONTRACTS Special Aspects of Contracting for Construction 436.209 Construction contracts with architect-engineer...

  20. 48 CFR 2936.209 - Construction contracts with architect-engineer firms.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... with architect-engineer firms. 2936.209 Section 2936.209 Federal Acquisition Regulations System DEPARTMENT OF LABOR GENERAL CONTRACTING REQUIREMENTS CONSTRUCTION AND ARCHITECT-ENGINEER CONTRACTS Special Aspects of Contracting for Construction 2936.209 Construction contracts with architect-engineer firms. As...

  1. 48 CFR 1536.209 - Construction contracts with architect-engineer firms.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... with architect-engineer firms. 1536.209 Section 1536.209 Federal Acquisition Regulations System ENVIRONMENTAL PROTECTION AGENCY SPECIAL CATEGORIES OF CONTRACTING CONSTRUCTION AND ARCHITECT-ENGINEER CONTRACTS Special Aspects of Contracting for Construction 1536.209 Construction contracts with architect-engineer...

  2. 48 CFR 436.209 - Construction contracts with architect-engineer firms.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... with architect-engineer firms. 436.209 Section 436.209 Federal Acquisition Regulations System DEPARTMENT OF AGRICULTURE SPECIAL CATEGORIES OF CONTRACTING CONSTRUCTION AND ARCHITECT-ENGINEER CONTRACTS Special Aspects of Contracting for Construction 436.209 Construction contracts with architect-engineer...

  3. 48 CFR 436.209 - Construction contracts with architect-engineer firms.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... with architect-engineer firms. 436.209 Section 436.209 Federal Acquisition Regulations System DEPARTMENT OF AGRICULTURE SPECIAL CATEGORIES OF CONTRACTING CONSTRUCTION AND ARCHITECT-ENGINEER CONTRACTS Special Aspects of Contracting for Construction 436.209 Construction contracts with architect-engineer...

  4. 48 CFR 2936.209 - Construction contracts with architect-engineer firms.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... with architect-engineer firms. 2936.209 Section 2936.209 Federal Acquisition Regulations System DEPARTMENT OF LABOR GENERAL CONTRACTING REQUIREMENTS CONSTRUCTION AND ARCHITECT-ENGINEER CONTRACTS Special Aspects of Contracting for Construction 2936.209 Construction contracts with architect-engineer firms. As...

  5. 48 CFR 436.209 - Construction contracts with architect-engineer firms.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... with architect-engineer firms. 436.209 Section 436.209 Federal Acquisition Regulations System DEPARTMENT OF AGRICULTURE SPECIAL CATEGORIES OF CONTRACTING CONSTRUCTION AND ARCHITECT-ENGINEER CONTRACTS Special Aspects of Contracting for Construction 436.209 Construction contracts with architect-engineer...

  6. 48 CFR 1436.209 - Construction contracts with architect-engineer firms.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... with architect-engineer firms. 1436.209 Section 1436.209 Federal Acquisition Regulations System DEPARTMENT OF THE INTERIOR SPECIAL CATEGORIES OF CONTRACTING CONSTRUCTION AND ARCHITECT-ENGINEER CONTRACTS Special Aspects of Contracting for Construction 1436.209 Construction contracts with architect-engineer...

  7. 48 CFR 1536.209 - Construction contracts with architect-engineer firms.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... with architect-engineer firms. 1536.209 Section 1536.209 Federal Acquisition Regulations System ENVIRONMENTAL PROTECTION AGENCY SPECIAL CATEGORIES OF CONTRACTING CONSTRUCTION AND ARCHITECT-ENGINEER CONTRACTS Special Aspects of Contracting for Construction 1536.209 Construction contracts with architect-engineer...

  8. 48 CFR 1536.209 - Construction contracts with architect-engineer firms.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... with architect-engineer firms. 1536.209 Section 1536.209 Federal Acquisition Regulations System ENVIRONMENTAL PROTECTION AGENCY SPECIAL CATEGORIES OF CONTRACTING CONSTRUCTION AND ARCHITECT-ENGINEER CONTRACTS Special Aspects of Contracting for Construction 1536.209 Construction contracts with architect-engineer...

  9. 48 CFR 1536.209 - Construction contracts with architect-engineer firms.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... architect-engineer firms. 1536.209 Section 1536.209 Federal Acquisition Regulations System ENVIRONMENTAL PROTECTION AGENCY SPECIAL CATEGORIES OF CONTRACTING CONSTRUCTION AND ARCHITECT-ENGINEER CONTRACTS Special Aspects of Contracting for Construction 1536.209 Construction contracts with architect-engineer firms. (a...

  10. 48 CFR 2936.209 - Construction contracts with architect-engineer firms.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... with architect-engineer firms. 2936.209 Section 2936.209 Federal Acquisition Regulations System DEPARTMENT OF LABOR GENERAL CONTRACTING REQUIREMENTS CONSTRUCTION AND ARCHITECT-ENGINEER CONTRACTS Special Aspects of Contracting for Construction 2936.209 Construction contracts with architect-engineer firms. As...

  11. 48 CFR 1436.209 - Construction contracts with architect-engineer firms.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... with architect-engineer firms. 1436.209 Section 1436.209 Federal Acquisition Regulations System DEPARTMENT OF THE INTERIOR SPECIAL CATEGORIES OF CONTRACTING CONSTRUCTION AND ARCHITECT-ENGINEER CONTRACTS Special Aspects of Contracting for Construction 1436.209 Construction contracts with architect-engineer...

  12. 48 CFR 2936.209 - Construction contracts with architect-engineer firms.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... with architect-engineer firms. 2936.209 Section 2936.209 Federal Acquisition Regulations System DEPARTMENT OF LABOR GENERAL CONTRACTING REQUIREMENTS CONSTRUCTION AND ARCHITECT-ENGINEER CONTRACTS Special Aspects of Contracting for Construction 2936.209 Construction contracts with architect-engineer firms. As...

  13. 48 CFR 1536.209 - Construction contracts with architect-engineer firms.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... with architect-engineer firms. 1536.209 Section 1536.209 Federal Acquisition Regulations System ENVIRONMENTAL PROTECTION AGENCY SPECIAL CATEGORIES OF CONTRACTING CONSTRUCTION AND ARCHITECT-ENGINEER CONTRACTS Special Aspects of Contracting for Construction 1536.209 Construction contracts with architect-engineer...

  14. Design and Use of a Novel Bioreactor for Regeneration of Biaxially Stretched Tissue-Engineered Vessels

    PubMed Central

    Huang, Angela Hai; Lee, Yong-Ung; Calle, Elizabeth A.; Boyle, Michael; Starcher, Barry C.; Humphrey, Jay D.

    2015-01-01

    Conventional bioreactors are used to enhance extracellular matrix (ECM) production and mechanical strength of tissue-engineered vessels (TEVs) by applying circumferential strain, which is uniaxial stretching. However, the resulting TEVs still suffer from inadequate mechanical properties, where rupture strengths and compliance values are still very different from native arteries. The biomechanical milieu of native arteries consists of both circumferential and axial loading. Therefore, to better simulate the physiological stresses acting on native arteries, we built a novel bioreactor system to enable biaxial stretching of engineered arteries during culture. This new bioreactor system allows for independent control of circumferential and axial stretching parameters, such as displacement and beat rate. The assembly and setup processes for this biaxial bioreactor system are reliable with a success rate greater than 75% for completion of long-term sterile culture. This bioreactor also supports side-by-side assessments of TEVs that are cultured under three types of mechanical conditions (static, uniaxial, and biaxial), all within the same biochemical environment. Using this bioreactor, we examined the impact of biaxial stretching on arterial wall remodeling of TEVs. Biaxial TEVs developed the greatest wall thickness compared with static and uniaxial TEVs. Unlike uniaxial loading, biaxial loading led to undulated collagen fibers that are commonly found in native arteries. More importantly, the biaxial TEVs developed the most mature elastin in the ECM, both qualitatively and quantitatively. The presence of mature extracellular elastin along with the undulated collagen fibers may contribute to the observed vascular compliance in the biaxial TEVs. The current work shows that biaxial stretching is a novel and promising means to improve TEV generation. Furthermore, this novel system allows us to optimize biomechanical conditioning by unraveling the interrelationships among the applied mechanical stress, the resulting ECM properties, and the mechanics of TEVs. PMID:25669988

  15. Model-based morphological segmentation and labeling of coronary angiograms.

    PubMed

    Haris, K; Efstratiadis, S N; Maglaveras, N; Pappas, C; Gourassas, J; Louridas, G

    1999-10-01

    A method for extraction and labeling of the coronary arterial tree (CAT) using minimal user supervision in single-view angiograms is proposed. The CAT structural description (skeleton and borders) is produced, along with quantitative information for the artery dimensions and assignment of coded labels, based on a given coronary artery model represented by a graph. The stages of the method are: 1) CAT tracking and detection; 2) artery skeleton and border estimation; 3) feature graph creation; and iv) artery labeling by graph matching. The approximate CAT centerline and borders are extracted by recursive tracking based on circular template analysis. The accurate skeleton and borders of each CAT segment are computed, based on morphological homotopy modification and watershed transform. The approximate centerline and borders are used for constructing the artery segment enclosing area (ASEA), where the defined skeleton and border curves are considered as markers. Using the marked ASEA, an artery gradient image is constructed where all the ASEA pixels (except the skeleton ones) are assigned the gradient magnitude of the original image. The artery gradient image markers are imposed as its unique regional minima by the homotopy modification method, the watershed transform is used for extracting the artery segment borders, and the feature graph is updated. Finally, given the created feature graph and the known model graph, a graph matching algorithm assigns the appropriate labels to the extracted CAT using weighted maximal cliques on the association graph corresponding to the two given graphs. Experimental results using clinical digitized coronary angiograms are presented.

  16. Endothelial cells (ECs) for vascular tissue engineering: venous ECs are less thrombogenic than arterial ECs.

    PubMed

    Geenen, I L A; Molin, D G M; van den Akker, N M S; Jeukens, F; Spronk, H M; Schurink, G W H; Post, M J

    2015-05-01

    Primary endothelial cells (ECs) are the preferred cellular source for luminal seeding of tissue-engineered (TE) vascular grafts. Research into the potential of ECs for vascular TE has focused particularly on venous rather than arterial ECs. In this study we evaluated the functional characteristics of arterial and venous ECs, relevant for vascular TE. Porcine ECs were isolated from femoral artery (PFAECs) and vein (PFVECs). The proliferation rate was comparable for both EC sources, whereas migration, determined through a wound-healing assay, was less profound for PFVECs. EC adhesion was lower for PFVECs on collagen I, measured after 10 min of arterial shear stress. Gene expression was analysed by qRT-PCR for ECs cultured under static conditions and after exposure to arterial shear stress and revealed differences in gene expression, with lower expression of EphrinB2 and VCAM-1 and higher levels of vWF and COUP-TFII in PFVECs than in PFAECs. PFVECs exhibited diminished platelet adhesion under flow and cell-based thrombin generation was delayed for PFVECs, indicating diminished tissue factor (TF) activity. After stimulation, prostacyclin secretion, but not nitric oxide (NO), was lower in PFVECs. Our data support the use of venous ECs for TE because of their beneficial antithrombogenic profile. Copyright © 2012 John Wiley & Sons, Ltd.

  17. 48 CFR 36.209 - Construction contracts with architect-engineer firms.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... with architect-engineer firms. 36.209 Section 36.209 Federal Acquisition Regulations System FEDERAL ACQUISITION REGULATION SPECIAL CATEGORIES OF CONTRACTING CONSTRUCTION AND ARCHITECT-ENGINEER CONTRACTS Special Aspects of Contracting for Construction 36.209 Construction contracts with architect-engineer firms. No...

  18. 48 CFR 636.209 - Construction contracts with architect-engineer firms.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... with architect-engineer firms. 636.209 Section 636.209 Federal Acquisition Regulations System DEPARTMENT OF STATE SPECIAL CATEGORIES OF CONTRACTING CONSTRUCTION AND ARCHITECT-ENGINEER CONTRACTS Special Aspects of Contracting for Construction 636.209 Construction contracts with architect-engineer firms. The...

  19. 48 CFR 636.209 - Construction contracts with architect-engineer firms.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... with architect-engineer firms. 636.209 Section 636.209 Federal Acquisition Regulations System DEPARTMENT OF STATE SPECIAL CATEGORIES OF CONTRACTING CONSTRUCTION AND ARCHITECT-ENGINEER CONTRACTS Special Aspects of Contracting for Construction 636.209 Construction contracts with architect-engineer firms. The...

  20. 48 CFR 636.209 - Construction contracts with architect-engineer firms.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... with architect-engineer firms. 636.209 Section 636.209 Federal Acquisition Regulations System DEPARTMENT OF STATE SPECIAL CATEGORIES OF CONTRACTING CONSTRUCTION AND ARCHITECT-ENGINEER CONTRACTS Special Aspects of Contracting for Construction 636.209 Construction contracts with architect-engineer firms. The...

  1. 48 CFR 636.209 - Construction contracts with architect-engineer firms.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... with architect-engineer firms. 636.209 Section 636.209 Federal Acquisition Regulations System DEPARTMENT OF STATE SPECIAL CATEGORIES OF CONTRACTING CONSTRUCTION AND ARCHITECT-ENGINEER CONTRACTS Special Aspects of Contracting for Construction 636.209 Construction contracts with architect-engineer firms. The...

  2. 48 CFR 36.209 - Construction contracts with architect-engineer firms.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... with architect-engineer firms. 36.209 Section 36.209 Federal Acquisition Regulations System FEDERAL ACQUISITION REGULATION SPECIAL CATEGORIES OF CONTRACTING CONSTRUCTION AND ARCHITECT-ENGINEER CONTRACTS Special Aspects of Contracting for Construction 36.209 Construction contracts with architect-engineer firms. No...

  3. 48 CFR 636.209 - Construction contracts with architect-engineer firms.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... with architect-engineer firms. 636.209 Section 636.209 Federal Acquisition Regulations System DEPARTMENT OF STATE SPECIAL CATEGORIES OF CONTRACTING CONSTRUCTION AND ARCHITECT-ENGINEER CONTRACTS Special Aspects of Contracting for Construction 636.209 Construction contracts with architect-engineer firms. The...

  4. 48 CFR 2936.209 - Construction contracts with architect-engineer firms.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... architect-engineer firms. 2936.209 Section 2936.209 Federal Acquisition Regulations System DEPARTMENT OF LABOR GENERAL CONTRACTING REQUIREMENTS CONSTRUCTION AND ARCHITECT-ENGINEER CONTRACTS Special Aspects of Contracting for Construction 2936.209 Construction contracts with architect-engineer firms. As required by FAR...

  5. 48 CFR 36.209 - Construction contracts with architect-engineer firms.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... with architect-engineer firms. 36.209 Section 36.209 Federal Acquisition Regulations System FEDERAL ACQUISITION REGULATION SPECIAL CATEGORIES OF CONTRACTING CONSTRUCTION AND ARCHITECT-ENGINEER CONTRACTS Special Aspects of Contracting for Construction 36.209 Construction contracts with architect-engineer firms. No...

  6. 48 CFR 36.209 - Construction contracts with architect-engineer firms.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... with architect-engineer firms. 36.209 Section 36.209 Federal Acquisition Regulations System FEDERAL ACQUISITION REGULATION SPECIAL CATEGORIES OF CONTRACTING CONSTRUCTION AND ARCHITECT-ENGINEER CONTRACTS Special Aspects of Contracting for Construction 36.209 Construction contracts with architect-engineer firms. No...

  7. 48 CFR 36.209 - Construction contracts with architect-engineer firms.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... with architect-engineer firms. 36.209 Section 36.209 Federal Acquisition Regulations System FEDERAL ACQUISITION REGULATION SPECIAL CATEGORIES OF CONTRACTING CONSTRUCTION AND ARCHITECT-ENGINEER CONTRACTS Special Aspects of Contracting for Construction 36.209 Construction contracts with architect-engineer firms. No...

  8. Vascular anatomy of the stomach related to resection procedures strategy.

    PubMed

    Prudius, V; Procházka, V; Pavlovský, Z; Prudius, D; Kala, Z

    2017-04-01

    This study is focused on the vascular anatomy of the stomach in relation to the gastric pull-up construction. The vascular anatomy was studied on forty-one human specimens. We find out the differences in blood supplement between anterior and posterior wall. It was maked an review of the main trunk arteries of the stomach. To display the vessels of the stomach we used diaphanoscopy, digital shooting in special mode and micro preparation of the vessels. We find out that left gastric artery gives more branches to the posterior wall and right gastroepiploic artery (RGEA) gives more branches to the anterior wall. But brunches of RGEA are longer on the posterior wall than on the anterior. Also we are offering the new classification of the RGEA related to gastric pull-up construction. This classification based not only on the anatomical shapes of RGEA but on the properties of the flow dynamics through the artery.

  9. Mechanical preconditioning enables electrophysiologic coupling of skeletal myoblast cells to myocardium

    PubMed Central

    Treskes, Philipp; Cowan, Douglas B.; Stamm, Christof; Rubach, Martin; Adelmann, Roland; Wittwer, Thorsten; Wahlers, Thorsten

    2015-01-01

    Objective The effect of mechanical preconditioning on skeletal myoblasts in engineered tissue constructs was investigated to resolve issues associated with conduction block between skeletal myoblast cells and cardiomyocytes. Methods Murine skeletal myoblasts were used to generate engineered tissue constructs with or without application of mechanical strain. After in vitro myotube formation, engineered tissue constructs were co-cultured for 6 days with viable embryonic heart slices. With the use of sharp electrodes, electrical coupling between engineered tissue constructs and embryonic heart slices was assessed in the presence or absence of pharmacologic agents. Results The isolation and expansion procedure for skeletal myoblasts resulted in high yields of homogeneously desmin-positive (97.1% ± 0.1%) cells. Mechanical strain was exerted on myotubes within engineered tissue constructs during gelation of the matrix, generating preconditioned engineered tissue constructs. Electrical coupling between preconditioned engineered tissue constructs and embryonic heart slices was observed; however, no coupling was apparent when engineered tissue constructs were not subjected to mechanical strain. Coupling of cells from engineered tissue constructs to cells in embryonic heart slices showed slower conduction velocities than myocardial cells with the embryonic heart slices (preconditioned engineered tissue constructs vs embryonic heart slices: 0.04 ± 0.02 ms vs 0.10 ± 0.05 ms, P = .011), lower stimulation frequencies (preconditioned engineered tissue constructs vs maximum embryonic heart slices: 4.82 ± 1.42 Hz vs 10.58 ± 1.56 Hz; P = .0009), and higher sensitivities to the gap junction inhibitor (preconditioned engineered tissue constructs vs embryonic heart slices: 0.22 ± 0.07 mmol/L vs 0.93 ± 0.15 mmol/L; P = .0004). Conclusions We have generated skeletal myoblast–based transplantable grafts that electrically couple to myocardium. PMID:22980065

  10. Wall shear stress in intracranial aneurysms and adjacent arteries☆

    PubMed Central

    Wang, Fuyu; Xu, Bainan; Sun, Zhenghui; Wu, Chen; Zhang, Xiaojun

    2013-01-01

    Hemodynamic parameters play an important role in aneurysm formation and growth. However, it is difficult to directly observe a rapidly growing de novo aneurysm in a patient. To investigate possible associations between hemodynamic parameters and the formation and growth of intracranial aneurysms, the present study constructed a computational model of a case with an internal carotid artery aneurysm and an anterior communicating artery aneurysm, based on the CT angiography findings of a patient. To simulate the formation of the anterior communicating artery aneurysm and the growth of the internal carotid artery aneurysm, we then constructed a model that virtually removed the anterior communicating artery aneurysm, and a further two models that also progressively decreased the size of the internal carotid artery aneurysm. Computational simulations of the fluid dynamics of the four models were performed under pulsatile flow conditions, and wall shear stress was compared among the different models. In the three aneurysm growth models, increasing size of the aneurysm was associated with an increased area of low wall shear stress, a significant decrease in wall shear stress at the dome of the aneurysm, and a significant change in the wall shear stress of the parent artery. The wall shear stress of the anterior communicating artery remained low, and was significantly lower than the wall shear stress at the bifurcation of the internal carotid artery or the bifurcation of the middle cerebral artery. After formation of the anterior communicating artery aneurysm, the wall shear stress at the dome of the internal carotid artery aneurysm increased significantly, and the wall shear stress in the upstream arteries also changed significantly. These findings indicate that low wall shear stress may be associated with the initiation and growth of aneurysms, and that aneurysm formation and growth may influence hemodynamic parameters in the local and adjacent arteries. PMID:25206394

  11. Large Scale Expansion of Human Umbilical Cord Cells in a Rotating Bed System Bioreactor for Cardiovascular Tissue Engineering Applications

    PubMed Central

    Reichardt, Anne; Polchow, Bianca; Shakibaei, Mehdi; Henrich, Wolfgang; Hetzer, Roland; Lueders, Cora

    2013-01-01

    Widespread use of human umbilical cord cells for cardiovascular tissue engineering requires production of large numbers of well-characterized cells under controlled conditions. In current research projects, the expansion of cells to be used to create a tissue construct is usually performed in static cell culture systems which are, however, often not satisfactory due to limitations in nutrient and oxygen supply. To overcome these limitations dynamic cell expansion in bioreactor systems under controllable conditions could be an important tool providing continuous perfusion for the generation of large numbers of viable pre-conditioned cells in a short time period. For this purpose cells derived from human umbilical cord arteries were expanded in a rotating bed system bioreactor for up to 9 days. For a comparative study, cells were cultivated under static conditions in standard culture devices. Our results demonstrated that the microenvironment in the perfusion bioreactor was more favorable than that of the standard cell culture flasks. Data suggested that cells in the bioreactor expanded 39 fold (38.7 ± 6.1 fold) in comparison to statically cultured cells (31.8 ± 3.0 fold). Large-scale production of cells in the bioreactor resulted in more than 3 x 108 cells from a single umbilical cord fragment within 9 days. Furthermore cell doubling time was lower in the bioreactor system and production of extracellular matrix components was higher. With this study, we present an appropriate method to expand human umbilical cord artery derived cells with high cellular proliferation rates in a well-defined bioreactor system under GMP conditions. PMID:23847691

  12. Measuring Time-Averaged Blood Pressure

    NASA Technical Reports Server (NTRS)

    Rothman, Neil S.

    1988-01-01

    Device measures time-averaged component of absolute blood pressure in artery. Includes compliant cuff around artery and external monitoring unit. Ceramic construction in monitoring unit suppresses ebb and flow of pressure-transmitting fluid in sensor chamber. Transducer measures only static component of blood pressure.

  13. Transportation Infrastructure: Central Artery/Tunnel Project Faces Continued Financial Uncertainties

    DOT National Transportation Integrated Search

    1996-05-01

    At a cost of over $1 billion a mile, the Central Artery/Tunnel project - an Interstate Highway System project in Boston, Massachusetts - is one of the largest, most complex, and most expensive highway construction projects ever undertaken. In respons...

  14. Arterial grafts exhibiting unprecedented cellular infiltration and remodeling in vivo: the role of cells in the vascular wall.

    PubMed

    Row, Sindhu; Peng, Haofan; Schlaich, Evan M; Koenigsknecht, Carmon; Andreadis, Stelios T; Swartz, Daniel D

    2015-05-01

    To engineer and implant vascular grafts in the arterial circulation of a pre-clinical animal model and assess the role of donor medial cells in graft remodeling and function. Vascular grafts were engineered using Small Intestinal Submucosa (SIS)-fibrin hybrid scaffold and implanted interpositionally into the arterial circulation of an ovine model. We sought to demonstrate implantability of SIS-Fibrin based grafts; examine the remodeling; and determine whether the presence of vascular cells in the medial wall was necessary for cellular infiltration from the host and successful remodeling of the implants. We observed no occlusions or anastomotic complications in 18 animals that received these grafts. Notably, the grafts exhibited unprecedented levels of host cell infiltration that was not limited to the anastomotic sites but occurred through the lumen as well as the extramural side, leading to uniform cell distribution. Incoming cells remodeled the extracellular matrix and matured into functional smooth muscle cells as evidenced by expression of myogenic markers and development of vascular reactivity. Interestingly, tracking the donor cells revealed that their presence was beneficial but not necessary for successful grafting. Indeed, the proliferation rate and number of donor cells decreased over time as the vascular wall was dominated by host cells leading to significant remodeling and development of contractile function. These results demonstrate that SIS-Fibrin grafts can be successfully implanted into the arterial circulation of a clinically relevant animal model, improve our understanding of vascular graft remodeling and raise the possibility of engineering mural cell-free arterial grafts. Copyright © 2015 Elsevier Ltd. All rights reserved.

  15. Civil engineering reference guide

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Merritt, F.S.

    1986-01-01

    The civil engineering reference guide contains the following: Structural theory. Structural steel design. Concrete design and construction. Wood design and construction. Bridge engineering. Geotechnical engineering. Water engineering. Environmental engineering. Surveying.

  16. 22 CFR 228.17 - Special procurement rules for construction and engineering services.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... engineering services. 228.17 Section 228.17 Foreign Relations AGENCY FOR INTERNATIONAL DEVELOPMENT RULES FOR... construction and engineering services. Advanced developing countries, as defined in § 228.01, which USAID has... engineering services are not eligible to furnish USAID-financed construction and engineering services unless...

  17. 22 CFR 228.17 - Special procurement rules for construction and engineering services.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... engineering services. 228.17 Section 228.17 Foreign Relations AGENCY FOR INTERNATIONAL DEVELOPMENT RULES FOR... construction and engineering services. Advanced developing countries, as defined in § 228.01, which USAID has... engineering services are not eligible to furnish USAID-financed construction and engineering services unless...

  18. 22 CFR 228.17 - Special procurement rules for construction and engineering services.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... engineering services. 228.17 Section 228.17 Foreign Relations AGENCY FOR INTERNATIONAL DEVELOPMENT RULES FOR... construction and engineering services. Advanced developing countries, as defined in § 228.01, which USAID has... engineering services are not eligible to furnish USAID-financed construction and engineering services unless...

  19. Transportation Infrastructure: Progress on and Challenges to Central Artery/Tunnel Project's Cost and Financing

    DOT National Transportation Integrated Search

    1997-07-01

    The Central Artery/Tunnel project in Boston, Massachusetts--one of the largest, most complex, and most expensive highway construction projects ever undertaken--is well under way, with contracts worth nearly $8 billion either completed or awarded. Con...

  20. 25 CFR 700.465 - Technical feasibility.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... construction, technology, or another engineering project, however, an application for a construction, technology or another engineering project shall: (a) Include sufficient information to determine the nature... construction, technology, or other engineering project prior to construction. The Commission shall review the...

  1. 25 CFR 700.465 - Technical feasibility.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... construction, technology, or another engineering project, however, an application for a construction, technology or another engineering project shall: (a) Include sufficient information to determine the nature... construction, technology, or other engineering project prior to construction. The Commission shall review the...

  2. 25 CFR 700.465 - Technical feasibility.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... construction, technology, or another engineering project, however, an application for a construction, technology or another engineering project shall: (a) Include sufficient information to determine the nature... construction, technology, or other engineering project prior to construction. The Commission shall review the...

  3. 25 CFR 700.465 - Technical feasibility.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... construction, technology, or another engineering project, however, an application for a construction, technology or another engineering project shall: (a) Include sufficient information to determine the nature... construction, technology, or other engineering project prior to construction. The Commission shall review the...

  4. 25 CFR 700.465 - Technical feasibility.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... construction, technology, or another engineering project, however, an application for a construction, technology or another engineering project shall: (a) Include sufficient information to determine the nature... construction, technology, or other engineering project prior to construction. The Commission shall review the...

  5. LB03.04: SPHYGMOMANOMETER CUFF CONSTRUCTION AND MATERIALS AFFECT TRANSMISSION OF PRESSURE FROM CUFF TO ARTERIAL WALL. FINITE ELEMENT ANALYSIS OF HUMAN PRESSURE MEASUREMENTS AND DICOM DATA.

    PubMed

    Lewis, P; Naqvi, S; Mandal, P; Potluri, P

    2015-06-01

    Sphygmomanometer cuff pressure during deflation is assumed to equal systolic arterial pressure at the point of resumption of flow. Previous studies demonstrated that pressure decreases with increasing depth of soft tissues whilst visco-elastic characteristics of the arm tissue cause spatial and temporal variation in pressure magnitude. These generally used non-anatomical axisymmetrical arm simulations without incorporating arterial pressure variation. We used data from a volunteer's Magnetic Resonance (MR) arm scan and investigated the effect of variations in cuff materials and construction on the simulated transmission of pressure from under the cuff to the arterial wall under sinusoidal flow conditions. Pressure was measured under 8 different cuffs using Oxford Pressure Monitor Sensors placed at 90 degrees around the mid upper arm of a healthy male. Each cuff was inflated 3 times to 155 mmHg and then deflated to zero with 90 seconds between inflations. Young's modulus, flexural rigidity and thickness of each cuff was measured.Using DICOM data from the MR scan of the arm, a 3D model was derived using ScanIP and imported into Abaqus for Finite Element Analysis (FEA). Published mechanical properties of arm tissues and geometric non-linearity were assumed. The measured sub-cuff pressures were applied to the simulated arm and pressure was calculated around the brachial arterial wall. which was loaded with a sinusoidal pressure of 125/85 mmHg. FEA estimates of pressure around the brachial artery cuffs varied by up to 27 mmHg SBP and 17 mmHg DBP with different cuffs. Pressures within the cuffs varied up to 27 mmHg. Pressure transmission from the cuff to the arterial surface achieved a 95% transmission ratio with one rubber-bladdered cuff but varied between 76 and 88% for the others. Non-uniform pressure distribution around the arterial wall was strongly related to cuff fabric elastic modulus. Identical size cuffs with a separate rubber bladder produced peri-arterial pressure 14 mmHg higher than with a fabric bladder.(Figure is included in full-text article.) : Wide variations of pressure within and under cuffs and at the artery wall interface, dependent on differing cuff materials and construction, may critically affect blood pressure measurement.

  6. Bottom-up fabrication of artery-mimicking tubular co-cultures in collagen-based microchannel scaffolds.

    PubMed

    Tan, A; Fujisawa, K; Yukawa, Y; Matsunaga, Y T

    2016-10-20

    We developed a robust bottom-up approach to construct open-ended, tubular co-culture constructs that simulate the human vascular morphology and microenvironment. By design, these three-dimensional artificial vessels mimic the basic architecture of an artery: a collagen-rich extracellular matrix (as the tunica externa), smooth muscle cells (SMCs) (as the tunica media), and an endothelial cell (EC) lining (as the tunica interna). A versatile needle-based fabrication technique was employed to achieve controllable arterial layouts within a PDMS-hosted collagen microchannel scaffold (330 ± 10 μm in diameter): (direct co-culture) a SMC/EC bilayer to follow the structure of an arteriole-like segment; and (encapsulated co-culture) a lateral SMC multilayer covered by an EC monolayer lining to simulate the architecture of a larger artery. Optical and fluorescence microscopy images clearly evidenced the progressive cell elongation and sprouting behavior of SMCs and ECs along the collagen gel contour and within the gel matrix under static co-culture conditions. The progressive cell growth patterns effectively led to the formation of a tubular co-culture with an internal endothelial lining expressing prominent CD31 (cluster of differentiation 31) intercellular junction markers. During a 4-day static maturation period, the artery constructs showed modest alteration in the luminal diameters (i.e. less than 10% changes from the initial measurements). This argues in favor of stable and predictable arterial architecture achieved via the proposed fabrication protocols. Both co-culture models showed a high glucose metabolic rate during the initial proliferation phase, followed by a temporary quiescent (and thus, mature) stage. These proof-of-concept models with a controllable architecture create an important foundation for advanced vessel manipulations such as the integration of relevant physiological functionality or remodeling into a vascular disease-mimicking tissue.

  7. Towards a unified theory for morphomechanics

    PubMed Central

    Taber, Larry A.

    2009-01-01

    Mechanical forces are closely involved in the construction of an embryo. Experiments have suggested that mechanical feedback plays a role in regulating these forces, but the nature of this feedback is poorly understood. Here, we propose a general principle for the mechanics of morphogenesis, as governed by a pair of evolution equations based on feedback from tissue stress. In one equation, the rate of growth (or contraction) depends on the difference between the current tissue stress and a target (homeostatic) stress. In the other equation, the target stress changes at a rate that depends on the same stress difference. The parameters in these morphomechanical laws are assumed to depend on stress rate. Computational models are used to illustrate how these equations can capture a relatively wide range of behaviours observed in developing embryos, as well as show the limitations of this theory. Specific applications include growth of pressure vessels (e.g. the heart, arteries and brain), wound healing and sea urchin gastrulation. Understanding the fundamental principles of tissue construction can help engineers design new strategies for creating replacement tissues and organs in vitro. PMID:19657011

  8. Pulsatile blood flow in elastic artery with model aneurysm

    NASA Astrophysics Data System (ADS)

    Nikolov, N.; Radev, St.; Tabakova, S.

    2017-11-01

    The mathematical modeling and numerical simulations are expected to play an important role to predict the genesis of different cardiovascular diseases, such as the formation and rupture of aneurysms. In the present work, the numerical solutions of the oscillatory blood flow are constructed for an elastic artery with a model aneurysm by use of the software ANSYS. It is observed that the artery elastic strain behaves in a different way: stably or unstably depending on the different combinations between the flow parameter (outlet pressure) and the elastic modulus of the artery wall.

  9. URBAN PARTICLE-INDUCED PULMONARY ARTERY CONSTRUCTION IS MEDIATED BY SUPEROXIDE PRODUCTION

    EPA Science Inventory

    URBAN PARTICLE-INDUCED PULMONARY ARTERY CONSTRICTION IS MEDIATED BY SUPEROXIDE PRODUCTION.Jacqueline D. Carter, Zhuowei Li, Lisa A. Dailey, Yuh-Chin T. Huang. CEMALB, University of North Carolina, and ORD, US EPA, Chapel Hill, North Carolina.

    Exposure to particulate matter...

  10. 48 CFR 31.201-7 - Construction and architect-engineer contracts.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ...-engineer contracts. 31.201-7 Section 31.201-7 Federal Acquisition Regulations System FEDERAL ACQUISITION... Organizations 31.201-7 Construction and architect-engineer contracts. Specific principles and procedures for... architect-engineer contracts related to construction projects, are in 31.105. The applicability of these...

  11. 48 CFR 31.201-7 - Construction and architect-engineer contracts.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ...-engineer contracts. 31.201-7 Section 31.201-7 Federal Acquisition Regulations System FEDERAL ACQUISITION... Organizations 31.201-7 Construction and architect-engineer contracts. Specific principles and procedures for... architect-engineer contracts related to construction projects, are in 31.105. The applicability of these...

  12. 48 CFR 31.201-7 - Construction and architect-engineer contracts.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ...-engineer contracts. 31.201-7 Section 31.201-7 Federal Acquisition Regulations System FEDERAL ACQUISITION... Organizations 31.201-7 Construction and architect-engineer contracts. Specific principles and procedures for... architect-engineer contracts related to construction projects, are in 31.105. The applicability of these...

  13. 48 CFR 31.201-7 - Construction and architect-engineer contracts.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ...-engineer contracts. 31.201-7 Section 31.201-7 Federal Acquisition Regulations System FEDERAL ACQUISITION... Organizations 31.201-7 Construction and architect-engineer contracts. Specific principles and procedures for... architect-engineer contracts related to construction projects, are in 31.105. The applicability of these...

  14. 48 CFR 31.201-7 - Construction and architect-engineer contracts.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ...-engineer contracts. 31.201-7 Section 31.201-7 Federal Acquisition Regulations System FEDERAL ACQUISITION... Organizations 31.201-7 Construction and architect-engineer contracts. Specific principles and procedures for... architect-engineer contracts related to construction projects, are in 31.105. The applicability of these...

  15. Uterine Artery Embolization: An Analysis of Online Patient Information Quality and Readability with Historical Comparison.

    PubMed

    Murray, Timothy E; Mansoor, Tayyaub; Bowden, Dermot J; O'Neill, Damien C; Lee, Michael J

    2018-05-01

    Investigators aimed to assess online information describing uterine artery embolization (UAE) to examine the quality and readability of websites patients are accessing. A list of applicable, commonly used searchable terms was generated, including "Uterine Artery Embolization," "Fibroid Embolization," "Uterine Fibroid Embolization," and "Uterine Artery Embolisation." Each possible term was assessed across the five most-used English language search engines to determine the most commonly used term. The most common term was then investigated across each search engine, with the first 25 pages returned by each engine included for analysis. Duplicate pages, nontext content such as video or audio, and pages behind paywalls were excluded. Pages were analyzed for quality and readability using validated tools including DISCERN score, JAMA Benchmark Criteria, HONcode Certification, Flesch Reading Ease Score, Flesch-Kincaid Grade Level, and Gunning-Fog Index. Secondary features such as age, rank, author, and publisher were recorded. The most common applicable term was "Uterine Artery Embolization" (492,900 results). Mean DISCERN quality of information provided by UAE websites is "fair"; however, it has declined since comparative 2012 studies. Adherence to JAMA Benchmark Criteria has reduced to 6.7%. UAE website readability remains more difficult than the World Health Organization-recommended 7-8th grade reading levels. HONcode-certified websites (35.6%) demonstrated significantly higher quality than noncertified websites. Quality of online UAE information remains "fair." Adherence to JAMA benchmark criteria is poor. Readability is above recommended 7-8th grade levels. HONcode certification was predictive of higher website quality, a useful guide to patients requesting additional information. Copyright © 2018 The Association of University Radiologists. Published by Elsevier Inc. All rights reserved.

  16. 30 CFR 36.23 - Engine intake system.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 30 Mineral Resources 1 2014-07-01 2014-07-01 false Engine intake system. 36.23 Section 36.23... EQUIPMENT Construction and Design Requirements § 36.23 Engine intake system. (a) Construction. The intake... operator's compartment, to shut off the air supply to the engine. This valve shall be constructed to permit...

  17. 30 CFR 36.23 - Engine intake system.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 30 Mineral Resources 1 2012-07-01 2012-07-01 false Engine intake system. 36.23 Section 36.23... EQUIPMENT Construction and Design Requirements § 36.23 Engine intake system. (a) Construction. The intake... operator's compartment, to shut off the air supply to the engine. This valve shall be constructed to permit...

  18. Transplantation of Tissue-Engineered Cartilage in an Animal Model (Xenograft and Autograft): Construct Validation.

    PubMed

    Nemoto, Hitoshi; Watson, Deborah; Masuda, Koichi

    2015-01-01

    Tissue engineering holds great promise for cartilage repair with minimal donor-site morbidity. The in vivo maturation of a tissue-engineered construct can be tested in the subcutaneous tissues of the same species for autografts or of immunocompromised animals for allografts or xenografts. This section describes detailed protocols for the surgical transplantation of a tissue-engineered construct into an animal model to assess construct validity.

  19. 7 CFR 1717.604 - Long-range engineering plans and construction work plans.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 7 Agriculture 11 2010-01-01 2010-01-01 false Long-range engineering plans and construction work... AND GUARANTEED ELECTRIC LOANS Operational Controls § 1717.604 Long-range engineering plans and construction work plans. (a) All borrowers are required to maintain up-to-date long-range engineering plans and...

  20. 7 CFR 1717.604 - Long-range engineering plans and construction work plans.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... 7 Agriculture 11 2013-01-01 2013-01-01 false Long-range engineering plans and construction work... AND GUARANTEED ELECTRIC LOANS Operational Controls § 1717.604 Long-range engineering plans and construction work plans. (a) All borrowers are required to maintain up-to-date long-range engineering plans and...

  1. 7 CFR 1717.604 - Long-range engineering plans and construction work plans.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... 7 Agriculture 11 2014-01-01 2014-01-01 false Long-range engineering plans and construction work... AND GUARANTEED ELECTRIC LOANS Operational Controls § 1717.604 Long-range engineering plans and construction work plans. (a) All borrowers are required to maintain up-to-date long-range engineering plans and...

  2. 7 CFR 1717.604 - Long-range engineering plans and construction work plans.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... 7 Agriculture 11 2012-01-01 2012-01-01 false Long-range engineering plans and construction work... AND GUARANTEED ELECTRIC LOANS Operational Controls § 1717.604 Long-range engineering plans and construction work plans. (a) All borrowers are required to maintain up-to-date long-range engineering plans and...

  3. 7 CFR 1717.604 - Long-range engineering plans and construction work plans.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... 7 Agriculture 11 2011-01-01 2011-01-01 false Long-range engineering plans and construction work... AND GUARANTEED ELECTRIC LOANS Operational Controls § 1717.604 Long-range engineering plans and construction work plans. (a) All borrowers are required to maintain up-to-date long-range engineering plans and...

  4. 48 CFR 952.236 - Construction and architect-engineer contracts.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 48 Federal Acquisition Regulations System 5 2010-10-01 2010-10-01 false Construction and architect-engineer contracts. 952.236 Section 952.236 Federal Acquisition Regulations System DEPARTMENT OF ENERGY... Construction and architect-engineer contracts. ...

  5. 48 CFR 952.236 - Construction and architect-engineer contracts.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 48 Federal Acquisition Regulations System 5 2011-10-01 2011-10-01 false Construction and architect-engineer contracts. 952.236 Section 952.236 Federal Acquisition Regulations System DEPARTMENT OF ENERGY... Construction and architect-engineer contracts. ...

  6. 48 CFR 952.236 - Construction and architect-engineer contracts.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 48 Federal Acquisition Regulations System 5 2014-10-01 2014-10-01 false Construction and architect-engineer contracts. 952.236 Section 952.236 Federal Acquisition Regulations System DEPARTMENT OF ENERGY... Construction and architect-engineer contracts. ...

  7. 48 CFR 952.236 - Construction and architect-engineer contracts.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 48 Federal Acquisition Regulations System 5 2012-10-01 2012-10-01 false Construction and architect-engineer contracts. 952.236 Section 952.236 Federal Acquisition Regulations System DEPARTMENT OF ENERGY... Construction and architect-engineer contracts. ...

  8. 48 CFR 952.236 - Construction and architect-engineer contracts.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 48 Federal Acquisition Regulations System 5 2013-10-01 2013-10-01 false Construction and architect-engineer contracts. 952.236 Section 952.236 Federal Acquisition Regulations System DEPARTMENT OF ENERGY... Construction and architect-engineer contracts. ...

  9. Engineering poly(hydroxy butyrate-co-hydroxy valerate) based vascular scaffolds to mimic native artery.

    PubMed

    Deepthi, S; Nivedhitha Sundaram, M; Vijayan, Ponni; Nair, Shantikumar V; Jayakumar, R

    2018-04-01

    Electrospun tri-layered fibrous scaffold incorporating VEGF and Platelet Factor Concentrate (PFC) in multiple layers having different layer architectures was designed to mimic native artery. The scaffold consisted of longitudinally aligned poly(hydroxy butyrate-co-hydroxy valerate) (PHBV) and poly(vinyl alcohol) (PVA) nanofibers (inner layer), radially aligned PHBV-elastin nanofibers (middle layer) to provide the bi-directional alignment and combination of longitudinally aligned PHBV-elastin and random PHBV/PVA multiscale fibers (peripheral layer). Tubular constructs of diameter <6 mm were developed. The developed electrospun fibers were characterised by Scanning Electron Microscope (SEM), Fourier Transform Infrared Spectroscopy and Tensile tests. Further the burst strength, compliance and stiffness index of tri-layered tubular scaffold was evaluated. SEM images of fibrous layers showed the typical longitudinal and radial alignment of fibers in the tubular construct. SEM images showed that the prepared PHBV nanofibers were in the range of 500-800 nm and PHBV microfibers were of 1-2 μm in diameter in the tri-layered electrospun membrane. PVA nanofibers were of size 200-250 nm. The tensile strength, percentage compliance and stiffness index of tri-layered membrane was in accordance with that of native small blood vessels. The developed tri-layered membrane was blood compatible, with hemolysis degree 0.85 ± 0.21% and did not activate platelets. Controlled release of VEGF and PFC was observed from the scaffold. The biocompatibility of the tri-layered scaffold was evaluated using HUVECs, SMCs and MSCs and SMCs infiltration from the outer layer was also evaluated. Specific protein expression for the HUVECs and SMCs was evaluated by flow cytometry and immunocytochemistry. HUVECs and SMCs exhibited good elongation and alignment along the direction of fibers and was found to maintain its CD31, VE-Cadherin and αSMA expression respectively. The results highlight the importance of bi-directional fiber alignment on the tri-layered electrospun scaffold as a suitable architectural prototype for vascular scaffolds to mimic the native arteries. Copyright © 2017 Elsevier B.V. All rights reserved.

  10. Evaluation of Hybrid Learning in a Construction Engineering Context: A Mixed-Method Approach

    ERIC Educational Resources Information Center

    Karabulut-Ilgu, Aliye; Jahren, Charles

    2016-01-01

    Engineering educators call for a widespread implementation of hybrid learning to respond to rapidly changing demands of the 21st century. In response to this call, a junior-level course in the Construction Engineering program entitled Construction Equipment and Heavy Construction Methods was converted into a hybrid learning model. The overarching…

  11. Computational model-informed design and bioprinting of cell-patterned constructs for bone tissue engineering.

    PubMed

    Carlier, Aurélie; Skvortsov, Gözde Akdeniz; Hafezi, Forough; Ferraris, Eleonora; Patterson, Jennifer; Koç, Bahattin; Van Oosterwyck, Hans

    2016-05-17

    Three-dimensional (3D) bioprinting is a rapidly advancing tissue engineering technology that holds great promise for the regeneration of several tissues, including bone. However, to generate a successful 3D bone tissue engineering construct, additional complexities should be taken into account such as nutrient and oxygen delivery, which is often insufficient after implantation in large bone defects. We propose that a well-designed tissue engineering construct, that is, an implant with a specific spatial pattern of cells in a matrix, will improve the healing outcome. By using a computational model of bone regeneration we show that particular cell patterns in tissue engineering constructs are able to enhance bone regeneration compared to uniform ones. We successfully bioprinted one of the most promising cell-gradient patterns by using cell-laden hydrogels with varying cell densities and observed a high cell viability for three days following the bioprinting process. In summary, we present a novel strategy for the biofabrication of bone tissue engineering constructs by designing cell-gradient patterns based on a computational model of bone regeneration, and successfully bioprinting the chosen design. This integrated approach may increase the success rate of implanted tissue engineering constructs for critical size bone defects and also can find a wider application in the biofabrication of other types of tissue engineering constructs.

  12. Intraoperative left subclavian artery occlusion with left hand ischaemia and steal syndrome in the left internal thoracic artery

    PubMed Central

    Jelenc, Matija; Kneževič, Ivan; Stankovič, Milenko; Geršak, Borut

    2012-01-01

    We present a case of a 62-year old man with a left main stenosis, left coronary artery dominance, normal ejection fraction and no valvular pathology, and status post right carotid artery stenting, who was scheduled for elective coronary revascularization. We performed off-pump coronary revascularization, anastomosing the left internal thoracic artery to the left anterior descending artery, and three separate saphenous vein grafts to the intermediate artery and the first and second obtuse marginals, respectively. Proximally, the right internal thoracic artery was used as the inflow for all three venous grafts due to a heavily calcified ascending aorta. During the construction of the distal anastomoses to the obtuse marginals, the arterial pressure in the left radial artery suddenly dropped. The left hand was found to be pale and pulseless. A femoral artery catheter was placed for pressure monitoring and the anastomoses were completed as planned. Intraoperative transit-time graft flow measurement showed a reversed flow in the left internal thoracic artery. Postoperatively, angiography was performed showing a subtotal stenosis of the proximal left subclavian artery. The artery was dilated and stented. The postoperative course was uneventful and the patient was discharged on the 12th postoperative day. PMID:22767542

  13. Cryopreservation of human vascular umbilical cord cells under good manufacturing practice conditions for future cell banks.

    PubMed

    Polchow, Bianca; Kebbel, Kati; Schmiedeknecht, Gerno; Reichardt, Anne; Henrich, Wolfgang; Hetzer, Roland; Lueders, Cora

    2012-05-16

    In vitro fabricated tissue engineered vascular constructs could provide an alternative to conventional substitutes. A crucial factor for tissue engineering of vascular constructs is an appropriate cell source. Vascular cells from the human umbilical cord can be directly isolated and cryopreserved until needed. Currently no cell bank for human vascular cells is available. Therefore, the establishment of a future human vascular cell bank conforming to good manufacturing practice (GMP) conditions is desirable for therapeutic applications such as tissue engineered cardiovascular constructs. A fundamental step was the adaption of conventional research and development starting materials to GMP compliant starting materials. Human umbilical cord artery derived cells (HUCAC) and human umbilical vein endothelial cells (HUVEC) were isolated, cultivated, cryopreserved (short- and long-term) directly after primary culture and recultivated subsequently. Cell viability, expression of cellular markers and proliferation potential of fresh and cryopreserved cells were studied using trypan blue staining, flow cytometry analysis, immunofluorescence staining and proliferation assays. Statistical analyses were performed using Student's t-test. Sufficient numbers of isolated cells with acceptable viabilities and homogenous expression of cellular markers confirmed that the isolation procedure was successful using GMP compliant starting materials. The influence of cryopreservation was marginal, because cryopreserved cells mostly maintain phenotypic and functional characteristics similar to those of fresh cells. Phenotypic studies revealed that fresh cultivated and cryopreserved HUCAC were positive for alpha smooth muscle actin, CD90, CD105, CD73, CD29, CD44, CD166 and negative for smoothelin. HUVEC expressed CD31, CD146, CD105 and CD144 but not alpha smooth muscle actin. Functional analysis demonstrated acceptable viability and sufficient proliferation properties of cryopreserved HUCAC and HUVEC. Adaptation of cell isolation, cultivation and cryopreservation to GMP compliant starting materials was successful. Cryopreservation did not influence cell properties with lasting impact, confirming that the application of vascular cells from the human umbilical cord is feasible for cell banking. A specific cellular marker expression profile was established for HUCAC and HUVEC using flow cytometry analysis, applicable as a GMP compliant quality control. Use of these cells for the future fabrication of advanced therapy medicinal products GMP conditions are required by the regulatory authority.

  14. [Characteristics of porcine thoracic arteries fixed with polyepoxy compound].

    PubMed

    Yu, Xi-Xun; Chen, Huai-Qing

    2005-09-01

    To investigate the characteristics of porcine thoracic arteries fixed with ethylene glycol diglycidyl ether (EX-810) and to provide the proper scaffold materials for tissue-engineered blood vessel. The porcine thoracic arteries were respectively treated with 40 ml/L EX-810 and 6.25 g/L glutaraldehyde, and then they were examined with naked-eye, light microscope and scanning electron microscope. The fixation index determination, the amino acid analysis and the biomechanics test were also performed. The antigenicity of vascular tissues can be diminished by EX-810 through getting rid of cell in the vascular tissues or reducing the level of free amino groups in the vascular tissues. The structural integrity of vascular tissues can be preserved after treatment with EX-810. It was also found that the EX-810-fixed porcine vascular tissues appeared more similar to the natural vascular tissues in color and mechanical properties, and were more pliable than the glutaraldehyde-fixed tissues. The EX-810-fixed porcine thoracic arteries with low cytotoxicity and low antigenicity showed favorable characteristic similar to those of natural vessel, and it should be a promising material for fabricating scaffold of tissue-engineered blood vessel.

  15. Changes in blood flow due to stented parent artery expansion in an intracranial aneurysm.

    PubMed

    Mori, Futoshi; Ohta, Makoto; Matsuzawa, Teruo

    2015-01-01

    Stent placement is thought to obstruct the inflow of blood to an aneurysm. However, we introduced parent artery expansion and demonstrated that this may reduce the blood flow by the stent. In our previous study using idealized shapes, the results showed that flow reduction was greater than 22.2%, even if the expansion rate was only 6%. Furthermore, the parent artery expansion is predominantly caused by the effect of flow reduction as compared to that of flow reduction due to the obstruction of flow under stent placement. However, a realistic shape is complex and the blood flow also becomes complex flow. It is not understood whether the results of flow in the idealized shape are reflective of flow from a realistic 3D model. Therefore, we examined the effect of parent artery expansion using a realistic model. The aim is to clarify the effects of parent artery expansion on inflow rate, wall shear stress, and oscillatory shear index. We used a patient-specific geometry of a human internal carotid artery with an aneurysm. The geometry of parent artery expansion due to oversized stent constructed based on the voronoi diagram. We performed calculations in the unsteady-state situations using constructed models. The complexity of the flow in the aneurysm decreases in case of expanded parent artery. The inflow rate decreases by 33.6% immediately after parent artery expansion alone without a stent. The effect of the parent artery expansion on flow reduction is larger than that of the obstruction flow by stent placement. In addition, wall shear stress and oscillatory shear index on the aneurysm wall decrease by change in blood flow due to the parent artery expansion. The effects of the parent artery expansion in a realistic aneurysm model with different stent lengths were evaluated on the basis of a numerical simulation. Although the flow was complex, the parent artery expansion with stent reduces the inflow to the aneurysm and wall shear stress and oscillatory shear index on the aneurysm. Therefore, we suggest that changes in the blood flow because of the parent artery expansion may be identified and, sometimes, is more effective than the obstruction flow due to the stent placement.

  16. Computational fluid dynamics modeling of intracranial aneurysms: effects of parent artery segmentation on intra-aneurysmal hemodynamics.

    PubMed

    Castro, M A; Putman, C M; Cebral, J R

    2006-09-01

    The purpose of this study is to show the influence of the upstream parent artery geometry on intraaneurysmal hemodynamics of cerebral aneurysms. Patient-specific models of 4 cerebral aneurysms (1 posterior communicating artery [PcomA], 2 middle cerebral artery [MCA], and 1 anterior communicating artery [AcomA]) were constructed from 3D rotational angiography images. Two geometric models were constructed for each aneurysm. One model had the native parent vessel geometry; the second model was truncated approximately 1 cm upstream from the aneurysm, and the parent artery replaced with a straight cylinder. Corresponding finite element grids were generated and computational fluid dynamics simulations were carried out under pulsatile flow conditions. The intra-aneurysmal flow patterns and wall shear stress (WSS) distributions were visualized and compared. Models using the truncated parent vessel underestimated the WSS in the aneurysms in all cases and shifted the impaction zone to the neck compared with the native geometry. These effects were more pronounced in the PcomA and AcomA aneurysms where upstream curvature was substantial. The MCA aneurysm with a long M1 segment was the least effected. The more laminar flow pattern within the parent vessel in truncated models resulted in a less complex intra-aneurysmal flow patterns with fewer vortices and less velocity at the dome. Failure to properly model the inflow stream contributed by the upstream parent artery can significantly influence the results of intra-aneurysmal hemodynamic models. The upstream portion of the parent vessel of cerebral aneurysms should be included to accurately represent the intra-aneurysmal hemodynamics.

  17. 78 FR 77334 - Small Business Size Standards: Construction

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-12-23

    ... Dredging and Surface Cleanup Activities, an ``exception'' under Other Heavy and Civil Engineering... ``exception'' under Other Heavy and Civil Engineering Construction (NAICS 238910), from $20 million to $30... exception under Other Heavy and Civil Engineering Construction (NAICS 238910) and retain the current size...

  18. Economic Impact Forecast System (EIFS). Version 2.0. Users Manual. Supplement II. European Economic Impact Forecast System (EEIFS), Phase 1, (FRG/EIFS Pilot Model).

    DTIC Science & Technology

    1982-05-01

    Chmpip. tL : Construction engineering Research Laboratory ; available from NTIS. 1982. 71 p. (Technical report / Construction Engineering Researsh ...AD-Al17 661 CONSTRUCTION ENGINEERING RESEARCH LAB (ARMY) CHAMPAIGN IL F/G 5/3 ECONOMIC IMPACT FORECAST SYSTEM (EIFS). VERSION 2.0. USERS MANU--ETC(u...CONSTRUCTION ENGINEERING RESEARCH LABORATORY 4A762720A896-C-004 P.O. BOX 4005, CHAMPAIGN, IL 61820 I. CONTROLLING OFFICE NAME AND ADDRESS It. REPORT

  19. Cardiovascular Health and Arterial Stiffness: The Maine Syracuse Longitudinal Study

    PubMed Central

    Crichton, Georgina E; Elias, Merrill F; Robbins, Michael A

    2014-01-01

    Ideal cardiovascular health is a recently defined construct by the American Heart Association (AHA) to promote cardiovascular disease reduction. Arterial stiffness is a major risk factor for cardiovascular disease. The extent to which the presence of multiple prevalent cardiovascular risk factors and health behaviors is associated with arterial stiffness is unknown. The aim of this study was to examine the association between the AHA construct of cardiovascular health and arterial stiffness, as indexed by pulse wave velocity and pulse pressure. The AHA health metrics, comprising of four health behaviors (smoking, body mass index, physical activity, and diet) and three health factors (total cholesterol, blood pressure, and fasting plasma glucose) were evaluated among 505 participants in the Maine-Syracuse Longitudinal Study. Outcome measures were carotid-femoral pulse wave velocity (PWV) and pulse pressure measured at 4 to 5-year follow-up. Better cardiovascular health, comprising both health factors and behaviors, was associated with lower arterial stiffness, as indexed by pulse wave velocity and pulse pressure. Those with at least five health metrics at ideal levels had significantly lower PWV (9.8 m/s) than those with two or less ideal health metrics (11.7 m/s) (P<0.001). This finding remained with the addition of demographic and PWV-related variables (P=0.004). PMID:24384629

  20. Cardiovascular health and arterial stiffness: the Maine-Syracuse Longitudinal Study.

    PubMed

    Crichton, G E; Elias, M F; Robbins, M A

    2014-07-01

    Ideal cardiovascular health is a recently defined construct by the American Heart Association (AHA) to promote cardiovascular disease reduction. Arterial stiffness is a major risk factor for cardiovascular disease. The extent to which the presence of multiple prevalent cardiovascular risk factors and health behaviors is associated with arterial stiffness is unknown. The aim of this study was to examine the association between the AHA construct of cardiovascular health and arterial stiffness, as indexed by pulse wave velocity (PWV) and pulse pressure. The AHA health metrics, comprising of four health behaviors (smoking, body mass index, physical activity and diet) and three health factors (total cholesterol, blood pressure and fasting plasma glucose), were evaluated among 505 participants in the Maine-Syracuse Longitudinal Study. Outcome measures were carotid-femoral PWV and pulse pressure measured at 4- to 5-year follow-up. Better cardiovascular health, comprising both health factors and behaviors, was associated with lower arterial stiffness, as indexed by PWV and pulse pressure. Those with at least five health metrics at ideal levels had significantly lower PWV (9.8 m s(-1)) than those with two or less ideal health metrics (11.7 m s(-1)) (P < 0.001). This finding remained with the addition of demographic and PWV-related variables (P = 0.004).

  1. 48 CFR 853.236 - Construction and architect-engineer contracts.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 48 Federal Acquisition Regulations System 5 2012-10-01 2012-10-01 false Construction and architect-engineer contracts. 853.236 Section 853.236 Federal Acquisition Regulations System DEPARTMENT OF VETERANS AFFAIRS CLAUSES AND FORMS FORMS Prescription of Forms 853.236 Construction and architect-engineer...

  2. 48 CFR 853.236 - Construction and architect-engineer contracts.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 48 Federal Acquisition Regulations System 5 2014-10-01 2014-10-01 false Construction and architect-engineer contracts. 853.236 Section 853.236 Federal Acquisition Regulations System DEPARTMENT OF VETERANS AFFAIRS CLAUSES AND FORMS FORMS Prescription of Forms 853.236 Construction and architect-engineer...

  3. 48 CFR 853.236 - Construction and architect-engineer contracts.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 48 Federal Acquisition Regulations System 5 2010-10-01 2010-10-01 false Construction and architect-engineer contracts. 853.236 Section 853.236 Federal Acquisition Regulations System DEPARTMENT OF VETERANS AFFAIRS CLAUSES AND FORMS FORMS Prescription of Forms 853.236 Construction and architect-engineer...

  4. 48 CFR 853.236 - Construction and architect-engineer contracts.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 48 Federal Acquisition Regulations System 5 2011-10-01 2011-10-01 false Construction and architect-engineer contracts. 853.236 Section 853.236 Federal Acquisition Regulations System DEPARTMENT OF VETERANS AFFAIRS CLAUSES AND FORMS FORMS Prescription of Forms 853.236 Construction and architect-engineer...

  5. 48 CFR 853.236 - Construction and architect-engineer contracts.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 48 Federal Acquisition Regulations System 5 2013-10-01 2013-10-01 false Construction and architect-engineer contracts. 853.236 Section 853.236 Federal Acquisition Regulations System DEPARTMENT OF VETERANS AFFAIRS CLAUSES AND FORMS FORMS Prescription of Forms 853.236 Construction and architect-engineer...

  6. Engineering blood vessels by gene and cell therapy.

    PubMed

    Zarbiv, Gabriel; Preis, Meir; Ben-Yosef, Yaara; Flugelman, Moshe Y

    2007-08-01

    Cardiovascular-related syndromes are the leading cause of morbidity and mortality worldwide. Arterial narrowing and blockage due to atherosclerosis cause reduced blood flow to the brain, heart and legs. Bypass surgery to improve blood flow to the heart and legs in these patients is performed in hundreds of thousands of patients every year. Autologous grafts, such as the internal thoracic artery and saphenous vein, are used in most patients, but in a significant number of patients such grafts are not available and synthetic grafts are used. Synthetic grafts have higher failure rates than autologous grafts due to thrombosis and scar formation within graft lumen. Cell and gene therapy combined with tissue engineering hold a great promise to provide grafts that will be biocompatible and durable. This review describes the field of vascular grafts in the context of tissue engineering using cell and gene therapies.

  7. Elasticity assessment of electrospun nanofibrous vascular grafts: a comparison with femoral ovine arteries.

    PubMed

    Bagnasco, D Suarez; Ballarin, F Montini; Cymberknop, L J; Balay, G; Negreira, C; Abraham, G A; Armentano, R L

    2014-12-01

    Development of successful small-diameter vascular grafts constitutes a real challenge to biomaterial engineering. In most cases these grafts fail in-vivo due to the presence of a mechanical mismatch between the native vessel and the vascular graft. Biomechanical characterization of real native vessels provides significant information for synthetic graft development. Electrospun nanofibrous vascular grafts emerge as a potential tailor made solution to this problem. PLLA-electrospun nanofibrous tubular structures were prepared and selected as model bioresorbable grafts. An experimental setup, using gold standard and high resolution ultrasound techniques, was adapted to characterize in vitro the poly(L-lactic acid) (PLLA) electrospun structures. The grafts were subjected to near physiologic pulsated pressure conditions, following the pressure-diameter loop approach and the criteria stated in the international standard for cardiovascular implants-tubular vascular prostheses. Additionally, ovine femoral arteries were subjected to a similar evaluation. Measurements of pressure and diameter variations allowed the estimation of dynamical compliance (%C, 10(-2) mmHg) and the pressure-strain elastic modulus (E(Pε), 10(6) dyn cm(-2)) of the abovementioned vessels (grafts and arteries). Nanofibrous PLLA showed a decrease in %C (1.38±0.21, 0.93±0.13 and 0.76±0.15) concomitant to an increase in EPε (10.57±0.97, 14.31±1.47 and 17.63±2.61) corresponding to pressure ranges of 50 to 90 mmHg, 80 to 120 mmHg and 100 to 150 mmHg, respectively. Furthermore, femoral arteries exhibited a decrease in %C (8.52±1.15 and 0.79±0.20) and an increase in E(Pε) (1.66±0.30 and 15.76±4.78) corresponding to pressure ranges of 50-90 mmHg (elastin zone) and 100-130 mmHg (collagen zone). Arterial mechanics framework, extensively applied in our previous works, was successfully used to characterize PLLA vascular grafts in vitro, although its application can be directly extended to in vivo experiences, in conscious and chronically instrumented animals. The specific design and construction of the electrospun nanofibrous PLLA vascular grafts assessed in this work, showed similar mechanical properties as the ones observed in femoral arteries, at the collagen pressure range. Copyright © 2014 Elsevier B.V. All rights reserved.

  8. 14 CFR 33.31 - Applicability.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... STANDARDS: AIRCRAFT ENGINES Design and Construction; Reciprocating Aircraft Engines § 33.31 Applicability. This subpart prescribes additional design and construction requirements for reciprocating aircraft engines. ...

  9. 14 CFR 33.31 - Applicability.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... STANDARDS: AIRCRAFT ENGINES Design and Construction; Reciprocating Aircraft Engines § 33.31 Applicability. This subpart prescribes additional design and construction requirements for reciprocating aircraft engines. ...

  10. 14 CFR 33.61 - Applicability.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... STANDARDS: AIRCRAFT ENGINES Design and Construction; Turbine Aircraft Engines § 33.61 Applicability. This subpart prescribes additional design and construction requirements for turbine aircraft engines. ...

  11. 14 CFR 33.61 - Applicability.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... STANDARDS: AIRCRAFT ENGINES Design and Construction; Turbine Aircraft Engines § 33.61 Applicability. This subpart prescribes additional design and construction requirements for turbine aircraft engines. ...

  12. 14 CFR 33.61 - Applicability.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... STANDARDS: AIRCRAFT ENGINES Design and Construction; Turbine Aircraft Engines § 33.61 Applicability. This subpart prescribes additional design and construction requirements for turbine aircraft engines. ...

  13. Microfluidic perfusion culture system for multilayer artery tissue models.

    PubMed

    Yamagishi, Yuka; Masuda, Taisuke; Matsusaki, Michiya; Akashi, Mitsuru; Yokoyama, Utako; Arai, Fumihito

    2014-11-01

    We described an assembly technique and perfusion culture system for constructing artery tissue models. This technique differed from previous studies in that it does not require a solid biodegradable scaffold; therefore, using sheet-like tissues, this technique allowed the facile fabrication of tubular tissues can be used as model. The fabricated artery tissue models had a multilayer structure. The assembly technique and perfusion culture system were applicable to many different sizes of fabricated arteries. The shape of the fabricated artery tissue models was maintained by the perfusion culture system; furthermore, the system reproduced the in vivo environment and allowed mechanical stimulation of the arteries. The multilayer structure of the artery tissue model was observed using fluorescent dyes. The equivalent Young's modulus was measured by applying internal pressure to the multilayer tubular tissues. The aim of this study was to determine whether fabricated artery tissue models maintained their mechanical properties with developing. We demonstrated both the rapid fabrication of multilayer tubular tissues that can be used as model arteries and the measurement of their equivalent Young's modulus in a suitable perfusion culture environment.

  14. Morphological changes in paraurethral area after introduction of tissue engineering construct on the basis of adipose tissue stromal cells.

    PubMed

    Makarov, A V; Arutyunyan, I V; Bol'shakova, G B; Volkov, A V; Gol'dshtein, D V

    2009-10-01

    We studied morphological changes in the paraurethral area of Wistar rats after introduction of tissue engineering constructs on the basis of multipotent mesenchymal stem cells and gelatin sponge. The tissue engineering construct containing autologous culture of the stromal fraction of the adipose tissue was most effective. After introduction of this construct we observed more rapid degradation of the construct matrix and more intensive formation of collagen fibers.

  15. 20170312 - Adverse Outcome Pathway (AOP) framework for ...

    EPA Pesticide Factsheets

    Vascular development commences with de novo assembly of a primary capillary plexus (vasculogenesis) followed by its expansion (angiogenesis) and maturation (angio-adaptation) into a hierarchical system of arteries and veins. These processes are tightly regulated by genetic signals and environmental factors linked to morphogenesis and microphysiology. Gestational exposure to some chemicals disrupts vascular development leading to adverse outcomes. To broadly assess consequences of gestational toxicant exposure on vascular development, an Adverse Outcome Pathway (AOP) framework was constructed that integrates data from ToxCast high-throughput screening (HTS) assays with pathway-level information from the literature and public databases. The AOP-based model resolved the ToxCast library (1065 compounds) into a matrix based on several dozen molecular functions critical for developmental angiogenesis. A sample of 38 ToxCast chemicals selected across the matrix tested model performance. Putative vascular disrupting chemical (pVDC) bioactivity was assessed by multiple laboratories utilizing diverse angiogenesis assays, including: transgenic zebrafish, complex human cell co-cultures, engineered microscale systems, and human-synthetic models. The ToxCast pVDC signature predicted vascular disruption in a manner that was chemical-specific and assay-dependent. An AOP for developmental vascular toxicity was constructed that focuses on inhibition of VEGF receptor (VEGFR2). Thi

  16. Adverse Outcome Pathway (AOP) framework for embryonic ...

    EPA Pesticide Factsheets

    Vascular development commences with de novo assembly of a primary capillary plexus (vasculogenesis) followed by its expansion (angiogenesis) and maturation (angio-adaptation) into a hierarchical system of arteries and veins. These processes are tightly regulated by genetic signals and environmental factors linked to morphogenesis and microphysiology. Gestational exposure to some chemicals disrupts vascular development leading to adverse outcomes. To broadly assess consequences of gestational toxicant exposure on vascular development, an Adverse Outcome Pathway (AOP) framework was constructed that integrates data from ToxCast high-throughput screening (HTS) assays with pathway-level information from the literature and public databases. The AOP-based model resolved the ToxCast library (1065 compounds) into a matrix based on several dozen molecular functions critical for developmental angiogenesis. A sample of 38 ToxCast chemicals selected across the matrix tested model performance. Putative vascular disrupting chemical (pVDC) bioactivity was assessed by multiple laboratories utilizing diverse angiogenesis assays, including: transgenic zebrafish, complex human cell co-cultures, engineered microscale systems, and human-synthetic models. The ToxCast pVDC signature predicted vascular disruption in a manner that was chemical-specific and assay-dependent. An AOP for developmental vascular toxicity was constructed that focuses on inhibition of VEGF receptor (VEGFR2). Thi

  17. Smooth muscle cell seeding of decellularized scaffolds: the importance of bioreactor preconditioning to development of a more native architecture for tissue-engineered blood vessels.

    PubMed

    Yazdani, Saami K; Watts, Benjamin; Machingal, Masood; Jarajapu, Yagna P R; Van Dyke, Mark E; Christ, George J

    2009-04-01

    Vascular smooth muscle cells (VSMCs) impart important functional characteristics in the native artery and, therefore, should logically be incorporated in the development of tissue-engineered blood vessels. However, the native architecture and low porosity of naturally derived biomaterials (i.e., decellularized vessels) have impeded efforts to seed and incorporate a VSMC layer in tissue-engineered blood vessels. To this end, the goal of this study was to develop improved methods for seeding, proliferation, and maturation of VSMCs on decellularized porcine carotid arteries. Decellularized vessels were prepared in the absence and presence of the adventitial layer, and statically seeded with a pipette containing a suspension of rat aortic VSMCs. After cell seeding, recellularized engineered vessels were placed in a custom bioreactor system for 1-2 weeks to enhance cellular proliferation, alignment, and maturation. Initial attachment of VSMCs was dramatically enhanced by removing the adventitial layer of the decellularized porcine artery. Moreover, cyclic bioreactor conditioning (i.e., flow and pressure) resulted in increased VSMC proliferation and accelerated formation of a muscularized medial layer in the absence of the adventitial layer during the first week of preconditioning. Fura-2-based digital imaging microscopy revealed marked and reproducible depolarization-induced calcium mobilization after bioreactor preconditioning in the absence, but not in the presence, of the adventitia. The major finding of this investigation is that bioreactor preconditioning accelerates the formation of a significant muscular layer on decellularized scaffolds, in particular on adventitia-denuded scaffolds. Further, the VSMC layer of bioreactor-preconditioned vessels was capable of mobilizing calcium in response to cellular depolarization. These findings represent an important first step toward the development of tissue-engineered vascular grafts that more closely mimic native vasculature.

  18. Tissue engineering of heart valves: in vitro experiences.

    PubMed

    Sodian, R; Hoerstrup, S P; Sperling, J S; Daebritz, S H; Martin, D P; Schoen, F J; Vacanti, J P; Mayer, J E

    2000-07-01

    Tissue engineering is a new approach, whereby techniques are being developed to transplant autologous cells onto biodegradable scaffolds to ultimately form new functional tissue in vitro and in vivo. Our laboratory has focused on the tissue engineering of heart valves, and we have fabricated a trileaflet heart valve scaffold from a biodegradable polymer, a polyhydroxyalkanoate. In this experiment we evaluated the suitability of this scaffold material as well as in vitro conditioning to create viable tissue for tissue engineering of a trileaflet heart valve. We constructed a biodegradable and biocompatible trileaflet heart valve scaffold from a porous polyhydroxyalkanoate (Meatabolix Inc, Cambridge, MA). The scaffold consisted of a cylindrical stent (1 x 15 x 20 mm inner diameter) and leaflets (0.3 mm thick), which were attached to the stent by thermal processing techniques. The porous heart valve scaffold (pore size 100 to 240 microm) was seeded with vascular cells grown and expanded from an ovine carotid artery and placed into a pulsatile flow bioreactor for 1, 4, and 8 days. Analysis of the engineered tissue included biochemical examination, enviromental scanning electron microscopy, and histology. It was possible to create a trileaflet heart valve scaffold from polyhydroxyalkanoate, which opened and closed synchronously in a pulsatile flow bioreactor. The cells grew into the pores and formed a confluent layer after incubation and pulsatile flow exposure. The cells were mostly viable and formed connective tissue between the inside and the outside of the porous heart valve scaffold. Additionally, we demonstrated cell proliferation (DNA assay) and the capacity to generate collagen as measured by hydroxyproline assay and movat-stained glycosaminoglycans under in vitro pulsatile flow conditions. Polyhydroxyalkanoates can be used to fabricate a porous, biodegradable heart valve scaffold. The cells appear to be viable and extracellular matrix formation was induced after pulsatile flow exposure.

  19. [Design and verification of Luo-Ye pump-based stress formation for cultivation of tissue-engineered blood vessel].

    PubMed

    Liao, Wen-Jun; Chen, Wan-Wen; Wen, Zhang; Wu, Yue-Heng; Li, Dong-Feng; Zhou, Jia-Hui; Zheng, Jian-Yi; Lin, Zhan-Yi

    2016-06-20

    To improve Luo-Ye pump-based stress-forming system and optimize the stimulating effect on smooth muscle cells during cultivation of tissue-engineered blood vessels (TEBV). A new Luo-Ye pump-based TEBV 3D culture system was developed by adding an air pump to the output of the bioreactor. A pressure guide wire was used to measure the stress at different points of the silicone tube inside the TEBV bio-reactor, and fitting curves of the stress changes over time was created using Origin 8.0 software. The TEBVs were constructed by seeding vascular smooth muscle cells (VSMCs) isolated from human umbilical artery on polyglycolic acid (PGA) and cultured under dynamic conditions with 40 mmHg resistance (improved group), dynamic conditions without resistance (control group) or static condition (static group) for 4 weeks. The harvested TEBVs were then examined with HE staining, masson staining, α-SMA immunohistochemical staining, and scanning and transmission electron microscopy with semi-quantitative analysis of collagen content and α-SMA expression. The measured stress values and the fitting curves showed that the stress stimuli from the Luo-Ye pump were enhanced by adding an air pump to the output of the bioreactor. Histological analysis revealed improved VSMC density, collagen content and α-SMA expression in the TEBVs constructed with the improved method as compared with those in the control and static groups. Adding an air pump to the Luo-Ye pump significantly enhances the stress stimulation in the TEBV 3-D culture system to promote the secretion function of VSMCs.

  20. Micrometer scale guidance of mesenchymal stem cells to form structurally oriented large-scale tissue engineered cartilage.

    PubMed

    Chou, Chih-Ling; Rivera, Alexander L; Williams, Valencia; Welter, Jean F; Mansour, Joseph M; Drazba, Judith A; Sakai, Takao; Baskaran, Harihara

    2017-09-15

    Current clinical methods to treat articular cartilage lesions provide temporary relief of the symptoms but fail to permanently restore the damaged tissue. Tissue engineering, using mesenchymal stem cells (MSCs) combined with scaffolds and bioactive factors, is viewed as a promising method for repairing cartilage injuries. However, current tissue engineered constructs display inferior mechanical properties compared to native articular cartilage, which could be attributed to the lack of structural organization of the extracellular matrix (ECM) of these engineered constructs in comparison to the highly oriented structure of articular cartilage ECM. We previously showed that we can guide MSCs undergoing chondrogenesis to align using microscale guidance channels on the surface of a two-dimensional (2-D) collagen scaffold, which resulted in the deposition of aligned ECM within the channels and enhanced mechanical properties of the constructs. In this study, we developed a technique to roll 2-D collagen scaffolds containing MSCs within guidance channels in order to produce a large-scale, three-dimensional (3-D) tissue engineered cartilage constructs with enhanced mechanical properties compared to current constructs. After rolling the MSC-scaffold constructs into a 3-D cylindrical structure, the constructs were cultured for 21days under chondrogenic culture conditions. The microstructure architecture and mechanical properties of the constructs were evaluated using imaging and compressive testing. Histology and immunohistochemistry of the constructs showed extensive glycosaminoglycan (GAG) and collagen type II deposition. Second harmonic generation imaging and Picrosirius red staining indicated alignment of neo-collagen fibers within the guidance channels of the constructs. Mechanical testing indicated that constructs containing the guidance channels displayed enhanced compressive properties compared to control constructs without these channels. In conclusion, using a novel roll-up method, we have developed large scale MSC based tissue-engineered cartilage that shows microscale structural organization and enhanced compressive properties compared to current tissue engineered constructs. Tissue engineered cartilage constructs made with human mesenchymal stem cells (hMSCs), scaffolds and bioactive factors are a promising solution to treat cartilage defects. A major disadvantage of these constructs is their inferior mechanical properties compared to the native tissue, which is likely due to the lack of structural organization of the extracellular matrix of the engineered constructs. In this study, we developed three-dimensional (3-D) cartilage constructs from rectangular scaffold sheets containing hMSCs in micro-guidance channels and characterized their mechanical properties and metabolic requirements. The work led to a novel roll-up method to embed 2-D microscale structures in 3-D constructs. Further, micro-guidance channels incorporated within the 3-D cartilage constructs led to the production of aligned cell-produced matrix and enhanced mechanical function. Copyright © 2017 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.

  1. 77 FR 3070 - Electric Engineering, Architectural Services, Design Policies and Construction Standards

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-01-23

    ... Engineering, Architectural Services, Design Policies and Construction Standards AGENCY: Rural Utilities..., engineering services and architectural services for transactions above the established threshold dollar levels... Code of Federal Regulations as follows: PART 1724--ELECTRIC ENGINEERING, ARCHITECTURAL SERVICES AND...

  2. A puzzle assembly strategy for fabrication of large engineered cartilage tissue constructs.

    PubMed

    Nover, Adam B; Jones, Brian K; Yu, William T; Donovan, Daniel S; Podolnick, Jeremy D; Cook, James L; Ateshian, Gerard A; Hung, Clark T

    2016-03-21

    Engineering of large articular cartilage tissue constructs remains a challenge as tissue growth is limited by nutrient diffusion. Here, a novel strategy is investigated, generating large constructs through the assembly of individually cultured, interlocking, smaller puzzle-shaped subunits. These constructs can be engineered consistently with more desirable mechanical and biochemical properties than larger constructs (~4-fold greater Young׳s modulus). A failure testing technique was developed to evaluate the physiologic functionality of constructs, which were cultured as individual subunits for 28 days, then assembled and cultured for an additional 21-35 days. Assembled puzzle constructs withstood large deformations (40-50% compressive strain) prior to failure. Their ability to withstand physiologic loads may be enhanced by increases in subunit strength and assembled culture time. A nude mouse model was utilized to show biocompatibility and fusion of assembled puzzle pieces in vivo. Overall, the technique offers a novel, effective approach to scaling up engineered tissues and may be combined with other techniques and/or applied to the engineering of other tissues. Future studies will aim to optimize this system in an effort to engineer and integrate robust subunits to fill large defects. Copyright © 2016 Elsevier Ltd. All rights reserved.

  3. A Puzzle Assembly Strategy for Fabrication of Large Engineered Cartilage Tissue Constructs

    PubMed Central

    Nover, Adam B.; Jones, Brian K.; Yu, William T.; Donovan, Daniel S.; Podolnick, Jeremy D.; Cook, James L.; Ateshian, Gerard A.; Hung, Clark T.

    2016-01-01

    Engineering of large articular cartilage tissue constructs remains a challenge as tissue growth is limited by nutrient diffusion. Here, a novel strategy is investigated, generating large constructs through the assembly of individually cultured, interlocking, smaller puzzle-shaped subunits. These constructs can be engineered consistently with more desirable mechanical and biochemical properties than larger constructs (~4-fold greater Young's modulus). A failure testing technique was developed to evaluate the physiologic functionality of constructs, which were cultured as individual subunits for 28 days, then assembled and cultured for an additional 21-35 days. Assembled puzzle constructs withstood large deformations (40-50% compressive strain) prior to failure. Their ability to withstand physiologic loads may be enhanced by increases in subunit strength and assembled culture time. A nude mouse model was utilized to show biocompatibility and fusion of assembled puzzle pieces in vivo. Overall, the technique offers a novel, effective approach to scaling up engineered tissues and may be combined with other techniques and/or applied to the engineering of other tissues. Future studies will aim to optimize this system in an effort to engineer and integrate robust subunits to fill large defects. PMID:26895780

  4. The 300 H.P. Benz Aircraft Engine

    NASA Technical Reports Server (NTRS)

    Heller, A

    1921-01-01

    A description is given of the Benz 12-cylinder aircraft engine. The 300 H.P. engine, with the cylinders placed at an angle of 60 degrees not only realizes a long-cherished conception, but has received refinement in detail. It may be described as a perfect example of modern German aircraft engine construction. Here, a detailed description is given of the construction of this engine. Emphasis is placed on the design and construction of the cylinders, pistons, and connecting rods. Also discussed are engine fitting, lubrication, oil pumps, bearings, the oil tank, fuel pump, carburetors, and cooling system.

  5. Construction and engineering of large biochemical pathways via DNA assembler

    PubMed Central

    Shao, Zengyi; Zhao, Huimin

    2015-01-01

    Summary DNA assembler enables rapid construction and engineering of biochemical pathways in a one-step fashion by exploitation of the in vivo homologous recombination mechanism in Saccharomyces cerevisiae. It has many applications in pathway engineering, metabolic engineering, combinatorial biology, and synthetic biology. Here we use two examples including the zeaxanthin biosynthetic pathway and the aureothin biosynthetic gene cluster to describe the key steps in the construction of pathways containing multiple genes using the DNA assembler approach. Methods for construct design, pathway assembly, pathway confirmation, and functional analysis are shown. The protocol for fine genetic modifications such as site-directed mutagenesis for engineering the aureothin gene cluster is also illustrated. PMID:23996442

  6. An Evaluation of the Pavement Condition Index Prediction Model for Rigid Airfield Pavements

    DTIC Science & Technology

    1982-09-01

    UNCLASSIFIED SECURITY CLASSIFICATION OF THIS PAGO(I*%A Data Entotoi) The United States Army Corps of Engineers, Construction Engineering Research Laboratory...Condition . . . 31 Pavement Design/ Construction ....... . 82 Aircraft Traffic ........ .............. 82 Climate Conditions ........ ............. 84...PATTERSON AFB . . . . . . . . . . . . . . . . . . . . . . . . . 155 C. DATA OBTAINED FROM THE CONSTRUCTION ENGINEERING RESEARCH LABORATORY. .. .. 168 D

  7. 48 CFR 1827.304-3 - Contracts for construction work or architect-engineer services. (NASA supplements paragraph (a))

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... work or architect-engineer services. (NASA supplements paragraph (a)) 1827.304-3 Section 1827.304-3... REQUIREMENTS PATENTS, DATA, AND COPYRIGHTS Patent Rights Under Government Contracts 1827.304-3 Contracts for construction work or architect-engineer services. (NASA supplements paragraph (a)) (a) For construction or...

  8. An update-tissue engineered nerve grafts for the repair of peripheral nerve injuries.

    PubMed

    Patel, Nitesh P; Lyon, Kristopher A; Huang, Jason H

    2018-05-01

    Peripheral nerve injuries (PNI) are caused by a range of etiologies and result in a broad spectrum of disability. While nerve autografts are the current gold standard for the reconstruction of extensive nerve damage, the limited supply of autologous nerve and complications associated with harvesting nerve from a second surgical site has driven groups from multiple disciplines, including biomedical engineering, neurosurgery, plastic surgery, and orthopedic surgery, to develop a suitable or superior alternative to autografting. Over the last couple of decades, various types of scaffolds, such as acellular nerve grafts (ANGs), nerve guidance conduits, and non-nervous tissues, have been filled with Schwann cells, stem cells, and/or neurotrophic factors to develop tissue engineered nerve grafts (TENGs). Although these have shown promising effects on peripheral nerve regeneration in experimental models, the autograft has remained the gold standard for large nerve gaps. This review provides a discussion of recent advances in the development of TENGs and their efficacy in experimental models. Specifically, TENGs have been enhanced via incorporation of genetically engineered cells, methods to improve stem cell survival and differentiation, optimized delivery of neurotrophic factors via drug delivery systems (DDS), co-administration of platelet-rich plasma (PRP), and pretreatment with chondroitinase ABC (Ch-ABC). Other notable advancements include conduits that have been bioengineered to mimic native nerve structure via cell-derived extracellular matrix (ECM) deposition, and the development of transplantable living nervous tissue constructs from rat and human dorsal root ganglia (DRG) neurons. Grafts composed of non-nervous tissues, such as vein, artery, and muscle, will be briefly discussed.

  9. 48 CFR 936.7101 - Construction contracts.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 48 Federal Acquisition Regulations System 5 2010-10-01 2010-10-01 false Construction contracts... CATEGORIES OF CONTRACTING CONSTRUCTION AND ARCHITECT-ENGINEER CONTRACTS Inspection and Acceptance 936.7101 Construction contracts. (a) Inspection services may be performed by the architect-engineer responsible for the...

  10. 48 CFR 936.7101 - Construction contracts.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 48 Federal Acquisition Regulations System 5 2011-10-01 2011-10-01 false Construction contracts... CATEGORIES OF CONTRACTING CONSTRUCTION AND ARCHITECT-ENGINEER CONTRACTS Inspection and Acceptance 936.7101 Construction contracts. (a) Inspection services may be performed by the architect-engineer responsible for the...

  11. 48 CFR 936.7101 - Construction contracts.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 48 Federal Acquisition Regulations System 5 2013-10-01 2013-10-01 false Construction contracts... CATEGORIES OF CONTRACTING CONSTRUCTION AND ARCHITECT-ENGINEER CONTRACTS Inspection and Acceptance 936.7101 Construction contracts. (a) Inspection services may be performed by the architect-engineer responsible for the...

  12. 48 CFR 936.7101 - Construction contracts.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 48 Federal Acquisition Regulations System 5 2012-10-01 2012-10-01 false Construction contracts... CATEGORIES OF CONTRACTING CONSTRUCTION AND ARCHITECT-ENGINEER CONTRACTS Inspection and Acceptance 936.7101 Construction contracts. (a) Inspection services may be performed by the architect-engineer responsible for the...

  13. 48 CFR 936.7101 - Construction contracts.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 48 Federal Acquisition Regulations System 5 2014-10-01 2014-10-01 false Construction contracts... CATEGORIES OF CONTRACTING CONSTRUCTION AND ARCHITECT-ENGINEER CONTRACTS Inspection and Acceptance 936.7101 Construction contracts. (a) Inspection services may be performed by the architect-engineer responsible for the...

  14. Study on evaluation of construction reliability for engineering project based on fuzzy language operator

    NASA Astrophysics Data System (ADS)

    Shi, Yu-Fang; Ma, Yi-Yi; Song, Ping-Ping

    2018-03-01

    System Reliability Theory is a research hotspot of management science and system engineering in recent years, and construction reliability is useful for quantitative evaluation of project management level. According to reliability theory and target system of engineering project management, the defination of construction reliability appears. Based on fuzzy mathematics theory and language operator, value space of construction reliability is divided into seven fuzzy subsets and correspondingly, seven membership function and fuzzy evaluation intervals are got with the operation of language operator, which provides the basis of corresponding method and parameter for the evaluation of construction reliability. This method is proved to be scientific and reasonable for construction condition and an useful attempt for theory and method research of engineering project system reliability.

  15. 48 CFR 31.105 - Construction and architect-engineer contracts.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ...-engineer contracts. 31.105 Section 31.105 Federal Acquisition Regulations System FEDERAL ACQUISITION... Construction and architect-engineer contracts. (a) This category includes all contracts and contract..., bridges, roads, or other kinds of real property. It also includes architect-engineer contracts related to...

  16. 48 CFR 836.209 - Construction contracts with architect-engineer firms.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... with architect-engineer firms. 836.209 Section 836.209 Federal Acquisition Regulations System DEPARTMENT OF VETERANS AFFAIRS SPECIAL CATEGORIES OF CONTRACTING CONSTRUCTION AND ARCHITECT-ENGINEER...-engineer firms. (a) When the contracting officer considers it necessary or advantageous to award a contract...

  17. 48 CFR 31.105 - Construction and architect-engineer contracts.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ...-engineer contracts. 31.105 Section 31.105 Federal Acquisition Regulations System FEDERAL ACQUISITION... Construction and architect-engineer contracts. (a) This category includes all contracts and contract..., bridges, roads, or other kinds of real property. It also includes architect-engineer contracts related to...

  18. 48 CFR 836.209 - Construction contracts with architect-engineer firms.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... with architect-engineer firms. 836.209 Section 836.209 Federal Acquisition Regulations System DEPARTMENT OF VETERANS AFFAIRS SPECIAL CATEGORIES OF CONTRACTING CONSTRUCTION AND ARCHITECT-ENGINEER...-engineer firms. (a) When the contracting officer considers it necessary or advantageous to award a contract...

  19. 48 CFR 836.209 - Construction contracts with architect-engineer firms.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... with architect-engineer firms. 836.209 Section 836.209 Federal Acquisition Regulations System DEPARTMENT OF VETERANS AFFAIRS SPECIAL CATEGORIES OF CONTRACTING CONSTRUCTION AND ARCHITECT-ENGINEER...-engineer firms. (a) When the contracting officer considers it necessary or advantageous to award a contract...

  20. 48 CFR 31.105 - Construction and architect-engineer contracts.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ...-engineer contracts. 31.105 Section 31.105 Federal Acquisition Regulations System FEDERAL ACQUISITION... Construction and architect-engineer contracts. (a) This category includes all contracts and contract..., bridges, roads, or other kinds of real property. It also includes architect-engineer contracts related to...

  1. 48 CFR 36.702 - Forms for use in contracting for architect-engineer services.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... contracting for architect-engineer services. 36.702 Section 36.702 Federal Acquisition Regulations System FEDERAL ACQUISITION REGULATION SPECIAL CATEGORIES OF CONTRACTING CONSTRUCTION AND ARCHITECT-ENGINEER CONTRACTS Standard and Optional Forms for Contracting for Construction, Architect-Engineer Services, and...

  2. 48 CFR 36.702 - Forms for use in contracting for architect-engineer services.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... contracting for architect-engineer services. 36.702 Section 36.702 Federal Acquisition Regulations System FEDERAL ACQUISITION REGULATION SPECIAL CATEGORIES OF CONTRACTING CONSTRUCTION AND ARCHITECT-ENGINEER CONTRACTS Standard and Optional Forms for Contracting for Construction, Architect-Engineer Services, and...

  3. 48 CFR 31.105 - Construction and architect-engineer contracts.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ...-engineer contracts. 31.105 Section 31.105 Federal Acquisition Regulations System FEDERAL ACQUISITION... Construction and architect-engineer contracts. (a) This category includes all contracts and contract..., bridges, roads, or other kinds of real property. It also includes architect-engineer contracts related to...

  4. 48 CFR 836.209 - Construction contracts with architect-engineer firms.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... with architect-engineer firms. 836.209 Section 836.209 Federal Acquisition Regulations System DEPARTMENT OF VETERANS AFFAIRS SPECIAL CATEGORIES OF CONTRACTING CONSTRUCTION AND ARCHITECT-ENGINEER...-engineer firms. (a) When the contracting officer considers it necessary or advantageous to award a contract...

  5. 48 CFR 836.209 - Construction contracts with architect-engineer firms.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... with architect-engineer firms. 836.209 Section 836.209 Federal Acquisition Regulations System DEPARTMENT OF VETERANS AFFAIRS SPECIAL CATEGORIES OF CONTRACTING CONSTRUCTION AND ARCHITECT-ENGINEER...-engineer firms. (a) When the contracting officer considers it necessary or advantageous to award a contract...

  6. 48 CFR 36.702 - Forms for use in contracting for architect-engineer services.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... contracting for architect-engineer services. 36.702 Section 36.702 Federal Acquisition Regulations System FEDERAL ACQUISITION REGULATION SPECIAL CATEGORIES OF CONTRACTING CONSTRUCTION AND ARCHITECT-ENGINEER CONTRACTS Standard and Optional Forms for Contracting for Construction, Architect-Engineer Services, and...

  7. Plaque components affect wall stress in stented human carotid artery: A numerical study

    NASA Astrophysics Data System (ADS)

    Fan, Zhen-Min; Liu, Xiao; Du, Cheng-Fei; Sun, An-Qiang; Zhang, Nan; Fan, Zhan-Ming; Fan, Yu-Bo; Deng, Xiao-Yan

    2016-12-01

    Carotid artery stenting presents challenges of in-stent restenosis and late thrombosis, which are caused primarily by alterations in the mechanical environment of the artery after stent implantation. The present study constructed patient-specific carotid arterial bifurcation models with lipid pools and calcified components based on magnetic resonance imaging. We numerically analyzed the effects of multicomponent plaques on the distributions of von Mises stresses (VMSs) in the patient-specific models after stenting. The results showed that when a stent was deployed, the large soft lipid pool in atherosclerotic plaques cushioned the host artery and reduced the stress within the arterial wall; however, this resulted in a sharp increase of VMS in the fibrous cap. When compared with the lipid pool, the presence of the calcified components led to slightly increased stresses on the luminal surface. However, when a calcification was located close to the luminal surface of the host artery and the stenosis, the local VMS was elevated. Overall, compared with calcified components, large lipid pools severely damaged the host artery after stenting. Furthermore, damage due to the calcified component may depend on location.

  8. Understanding and Improving Arterial Roads to Support Public Health and Transportation Goals.

    PubMed

    McAndrews, Carolyn; Pollack, Keshia M; Berrigan, David; Dannenberg, Andrew L; Christopher, Ed J

    2017-08-01

    Arterials are types of roads designed to carry high volumes of motorized traffic. They are an integral part of transportation systems worldwide and exposure to them is ubiquitous, especially in urban areas. Arterials provide access to diverse commercial and cultural resources, which can positively influence community health by supporting social cohesion as well as economic and cultural opportunities. They can negatively influence health via safety issues, noise, air pollution, and lack of economic development. The aims of public health and transportation partially overlap; efforts to improve arterials can meet goals of both professions. Two trends in arterial design show promise. First, transportation professionals increasingly define the performance of arterials via metrics accounting for pedestrians, cyclists, transit riders, and nearby residents in addition to motor vehicle users. Second, applying traffic engineering and design can generate safety, air quality, and livability benefits, but we need evidence to support these interventions. We describe the importance of arterials (including exposures, health behaviors, effects on equity, and resulting health outcomes) and make the case for public health collaborations with the transportation sector.

  9. A micromechanical device that monitors arterial pressure during general anesthesia and in intensive care units

    NASA Astrophysics Data System (ADS)

    Andreeva, A. V.; Luchinin, V. V.; Kuzmina, K. A.; Klyavinek, A. S.; Karelov, A. E.

    2015-12-01

    A vibroacoustic fiber optic system that consists of micromechanical components designated for use in medicine and biology is reviewed. A theoretical analysis of a fiber optic microphone is done and its optimal construction parameters are determined. The possibility of using the developed system with magnetic resonance tomography to noninvasively measure man's arterial pressure is specified.

  10. Design of a hydraulic analog of the circulatory system for evaluating artificial hearts.

    PubMed

    Donovan, F M

    1975-01-01

    A major problem in improving artificial heart designs is the absence of methods for accurate in vitro testing of artificial heart systems. A mock circulatory system has been constructed which hydraulically simulates the systemic and pulmonary circulations of the normal human. The device is constructed of 1/2 in. acrylic sheet and has overall dimensions of 24 in. wide, 16 in. tall, and 8 in. deep. The artificial heart to be tested is attached to the front of the device, and pumps fluid from the systemic venous chamber into the pulmonary arterial chamber and from the pulmonary venous chamber into the systemic arterial chamber. Each of the four chambers is hermetically sealed. The compliance of each chamber is determined by the volume of air trapped above the fluid in that chamber. The pulmonary and systemic resistances are set automatically by bellows-operated valves to simulate the barroreceptor response in the systemic arteries and the passive pulmonary resistance response in the pulmonary arteries. Cardiac output is measured by a turbine flowmeter in the systemic circulation. Results using the Kwan-Gett artificial heart show a good comparison between the mock circulatory system response and the calf response.

  11. Bioreactor-induced mesenchymal progenitor cell differentiation and elastic fiber assembly in engineered vascular tissues.

    PubMed

    Lin, Shigang; Mequanint, Kibret

    2017-09-01

    In vitro maturation of engineered vascular tissues (EVT) requires the appropriate incorporation of smooth muscle cells (SMC) and extracellular matrix (ECM) components similar to native arteries. To this end, the aim of the current study was to fabricate 4mm inner diameter vascular tissues using mesenchymal progenitor cells seeded into tubular scaffolds. A dual-pump bioreactor operating either in perfusion or pulsatile perfusion mode was used to generate physiological-like stimuli to promote progenitor cell differentiation, extracellular elastin production, and tissue maturation. Our data demonstrated that pulsatile forces and perfusion of 3D tubular constructs from both the lumenal and ablumenal sides with culture media significantly improved tissue assembly, effectively inducing mesenchymal progenitor cell differentiation to SMCs with contemporaneous elastin production. With bioreactor cultivation, progenitor cells differentiated toward smooth muscle lineage characterized by the expression of smooth muscle (SM)-specific markers smooth muscle alpha actin (SM-α-actin) and smooth muscle myosin heavy chain (SM-MHC). More importantly, pulsatile perfusion bioreactor cultivation enhanced the synthesis of tropoelastin and its extracellular cross-linking into elastic fiber compared with static culture controls. Taken together, the current study demonstrated progenitor cell differentiation and vascular tissue assembly, and provides insights into elastin synthesis and assembly to fibers. Incorporation of elastin into engineered vascular tissues represents a critical design goal for both mechanical and biological functions. In the present study, we seeded porous tubular scaffolds with multipotent mesenchymal progenitor cells and cultured in dual-pump pulsatile perfusion bioreactor. Physiological-like stimuli generated by bioreactor not only induced mesenchymal progenitor cell differentiation to vascular smooth muscle lineage but also actively promoted elastin synthesis and fiber assembly. Gene expression and protein synthesis analyses coupled with histological and immunofluorescence staining revealed that elastin-containing vascular tissues were fabricated. More importantly, co-localization and co-immunoprecipitation experiments demonstrated that elastin and fibrillin-1 were abundant throughout the cross-section of the tissue constructs suggesting a process of elastin protein crosslinking. This study paves a way forward to engineer elastin-containing functional vascular substitutes from multipotent progenitor cells in a bioreactor. Copyright © 2017 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.

  12. Seasonal trends in hypertension in Poland: evidence from Google search engine query data.

    PubMed

    Płatek, Anna E; Sierdziński, Janusz; Krzowski, Bartosz; Szymański, Filip M

    2018-01-01

    Various conditions, including arterial hypertension, exhibit seasonal trends in their occurrence and magnitude. Those trends correspond to an interest exhibited in the number of Internet searches for the specific conditions per month. The aim of the study was to show seasonal trends in the hypertension prevalence in Poland relate to the data from the Google Trends tool. Internet search engine query data were retrieved from Google Trends from January 2008 to November 2017. Data were calculated as a monthly normalised search volume from the nine-year period. Data was presented for specific geographic regions, including Poland, the United States of America, Australia, and worldwide for the following search terms: "arterial hypertension (pol. nadciśnienie tętnicze)", "hypertension (pol. nadciśnienie)" and "hypertension medical condition". Seasonal effects were calculated using regression models and presented graphically. In Poland the search volume is the highest between November and May, while patients exhibit the least interest in arterial hypertension during summer holidays (p < 0.05). Seasonal variations are comparable in the United States of America representing a Northern hemisphere country, while in Australia (Southern hemisphere) they exhibit a contrary trend. In conclusion, arterial hypertension is more likely to occur during winter months, which correlates with increased interest in the search phrase "hypertension" in Google.

  13. Polyphenol-Stabilized Tubular Elastin Scaffolds for Tissue Engineered Vascular Grafts

    PubMed Central

    Chuang, Ting-Hsien; Stabler, Christopher; Simionescu, Agneta

    2009-01-01

    Tissue-engineered vascular grafts require elastic, acellular porous scaffolds with controlled biodegradability and properties matching those of natural arteries. Elastin would be a desirable component for such applications, but elastin does not easily regenerate experimentally. Our approach is to develop tubular elastin scaffolds using decellularization and removal of collagen from porcine carotid arteries (∼5 mm diameter) using alkaline extraction. Because elastin is susceptible to rapid degeneration after implantation, scaffolds were further treated with penta-galloyl glucose (PGG), an established polyphenolic elastin-stabilizing agent. Scaffolds were compared in vitro with detergent-decellularized arteries for structure, composition, resistance to degradation, mechanical properties, and cytotoxicity and in vivo for cell infiltration and remodeling potential. Results showed effective decellularization and almost complete collagen removal by alkaline extraction. PGG-treated elastin scaffolds proved to be resistant to elastase digestion in vitro, maintained their cylindrical shapes, showed high resistance to burst pressures, and supported growth of endothelial cells and fibroblasts. In vivo results showed that PGG treatment reduced the rate of elastin biodegradation and controlled cell infiltration but did not hamper new collagen and proteoglycan deposition and secretion of matrix-degrading proteases. Alkali-purified, PGG-treated tubular arterial elastin scaffolds exhibit many desirable properties to be recommended for clinical applications as vascular grafts. PMID:19254115

  14. The effect of glycation on arterial microstructure and mechanical response.

    PubMed

    Stephen, Elizabeth A; Venkatasubramaniam, Arundhathi; Good, Theresa A; Topoleski, L D T

    2014-08-01

    Like engineered materials, an artery's biomechanical behavior and function depend on its microstructure. Glycation is associated with both normal aging and diabetes and has been shown to increase arterial stiffness. In this study we examined the direct effect of glycation on the mechanical response of intact arteries and on the mechanical response and structure of elastin isolated from the arteries. Samples of intact arteries and isolated elastin were prepared from porcine aortas and glycated. The mechanical response of all samples was completed using a uniaxial material test system. Glycation levels were measured using ELISA. A confocal microscope was used to image differences in the structure of the glycated and untreated elastin fibers. We found that, under the conditions used in this study, glycation led to decreased stiffness of elastin isolated from arteries, which was associated with a thinning of elastin fibers as imaged by confocal microscopy. We observed no effect of glycation on collagen fibers under our treatment conditions. These results suggest that glycation leads to weakening of the elastin component of arteries that could contribute to vascular defects seen in diabetes and aging. Prevention of glycation reactions may be an important consideration for vascular health later in life. © 2013 Wiley Periodicals, Inc.

  15. Solar power satellite system definition study. Part 2, volume 5: Space operations (construction and transportation)

    NASA Technical Reports Server (NTRS)

    Miller, K.; Davis, E. E.

    1977-01-01

    Construction and transportation systems and operations are described for the following combinations: (1) silicon photovoltaic CR=1 satellite constructed primarily in low earth orbit (LEO); (2) silicon photovoltaic CR=1 satellite constructed in geosynchronous earth orbit (GEO); (3) Rankine thermal engine satellite constructed primarily in LEO; and (4) Rankine thermal engine satellite constructed in GEO.

  16. Making Work: Demonstrating Thermodynamic Concepts with Solar-Powered Wax and Rubber Heat Engines

    ERIC Educational Resources Information Center

    Appleyard, S. J.

    2007-01-01

    Construction details are provided for simple heat engines that use candle wax and elastomers as working substances. The engines are constructed using common household materials and can be easily constructed in a school classroom or at home. They work reliably and are useful tools for demonstrating the conversion of heat to mechanical work. They…

  17. 49 CFR 268.21 - Down-selection of one or more Maglev projects for further study and selection of one project for...

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... further study and selection of one project for final design, engineering, and construction funding. 268.21... and selection of one project for final design, engineering, and construction funding. (a) Upon... analyses necessary prior to initiation of construction. Final design and engineering work will also be...

  18. 49 CFR 268.21 - Down-selection of one or more Maglev projects for further study and selection of one project for...

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... further study and selection of one project for final design, engineering, and construction funding. 268.21... and selection of one project for final design, engineering, and construction funding. (a) Upon... analyses necessary prior to initiation of construction. Final design and engineering work will also be...

  19. 49 CFR 268.21 - Down-selection of one or more Maglev projects for further study and selection of one project for...

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... further study and selection of one project for final design, engineering, and construction funding. 268.21... and selection of one project for final design, engineering, and construction funding. (a) Upon... analyses necessary prior to initiation of construction. Final design and engineering work will also be...

  20. 49 CFR 268.21 - Down-selection of one or more Maglev projects for further study and selection of one project for...

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... further study and selection of one project for final design, engineering, and construction funding. 268.21... and selection of one project for final design, engineering, and construction funding. (a) Upon... analyses necessary prior to initiation of construction. Final design and engineering work will also be...

  1. 49 CFR 268.21 - Down-selection of one or more Maglev projects for further study and selection of one project for...

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... further study and selection of one project for final design, engineering, and construction funding. 268.21... and selection of one project for final design, engineering, and construction funding. (a) Upon... analyses necessary prior to initiation of construction. Final design and engineering work will also be...

  2. Construction Strategy and Progress of Whole Intervertebral Disc Tissue Engineering.

    PubMed

    Yang, Qiang; Xu, Hai-wei; Hurday, Sookesh; Xu, Bao-shan

    2016-02-01

    Degenerative disc disease (DDD) is the major cause of low back pain, which usually leads to work absenteeism, medical visits and hospitalization. Because the current conservative procedures and surgical approaches to treatment of DDD only aim to relieve the symptoms of disease but not to regenerate the diseased disc, their long-term efficiency is limited. With the rapid developments in medical science, tissue engineering techniques have progressed markedly in recent years, providing a novel regenerative strategy for managing intervertebral disc disease. However, there are as yet no ideal methods for constructing tissue-engineered intervertebral discs. This paper reviews published reports pertaining to intervertebral disc tissue engineering and summarizes data concerning the seed cells and scaffold materials for tissue-engineered intervertebral discs, construction of tissue-engineered whole intervertebral discs, relevant animal experiments and effects of mechanics on the construction of tissue-engineered intervertebral disc and outlines the existing problems and future directions. Although the perfect regenerative strategy for treating DDD has not yet been developed, great progress has been achieved in the construction of tissue-engineered intervertebral discs. It is believed that ongoing research on intervertebral disc tissue engineering will result in revolutionary progress in the treatment of DDD. © 2016 Chinese Orthopaedic Association and John Wiley & Sons Australia, Ltd.

  3. Estimation of pressure gradients at renal artery stenoses

    NASA Astrophysics Data System (ADS)

    Yim, Peter J.; Cebral, Juan R.; Weaver, Ashley; Lutz, Robert J.; Vasbinder, G. Boudewijn C.

    2003-05-01

    Atherosclerotic disease of the renal artery can reduce the blood flow leading to renovascular hypertension and ischemic nephopathy. The kidney responds to a decrease in blood flow by activation of the renin-angiotensin system that increases blood pressure and can result in severe hypertension. Percutaneous translumenal angioplasty (PTA) may be indicated for treatment of renovascular hypertension (RVH). However, direct measurement of renal artery caliber and degree of stenosis has only moderate specificity for detection of RVH. A confounding factor in assessment of the proximal renal artery is that diffuse atherosclerotic disease of the distal branches of the renal artery can produce the same effect on blood-flow as atherosclerotic disease of the proximal renal artery. A methodology is proposed for estimation of pressure gradients at renal artery stenoses from magnetic resonance imaging that could improve the evaluation of renal artery disease. In the proposed methodology, pressure gradients are estimated using computational fluid dynamics (CFD) modeling. Realistic CFD models are constructed from images of vessel shape and measurements of blood-flow rates which are available from magnetic resonance angiography (MRA) and phase-contrast magnetic resonance (MR) imaging respectively. CFD measurement of renal artery pressure gradients has been validated in a physical flow-through model.

  4. 14 CFR 33.61 - Applicability.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... Aeronautics and Space FEDERAL AVIATION ADMINISTRATION, DEPARTMENT OF TRANSPORTATION AIRCRAFT AIRWORTHINESS STANDARDS: AIRCRAFT ENGINES Design and Construction; Turbine Aircraft Engines § 33.61 Applicability. This subpart prescribes additional design and construction requirements for turbine aircraft engines. ...

  5. 14 CFR 33.61 - Applicability.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... Aeronautics and Space FEDERAL AVIATION ADMINISTRATION, DEPARTMENT OF TRANSPORTATION AIRCRAFT AIRWORTHINESS STANDARDS: AIRCRAFT ENGINES Design and Construction; Turbine Aircraft Engines § 33.61 Applicability. This subpart prescribes additional design and construction requirements for turbine aircraft engines. ...

  6. 48 CFR 53.236 - Construction and architect-engineer contracts.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 48 Federal Acquisition Regulations System 2 2011-10-01 2011-10-01 false Construction and architect-engineer contracts. 53.236 Section 53.236 Federal Acquisition Regulations System FEDERAL ACQUISITION...-engineer contracts. ...

  7. 48 CFR 53.236 - Construction and architect-engineer contracts.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 48 Federal Acquisition Regulations System 2 2012-10-01 2012-10-01 false Construction and architect-engineer contracts. 53.236 Section 53.236 Federal Acquisition Regulations System FEDERAL ACQUISITION...-engineer contracts. ...

  8. 48 CFR 53.236 - Construction and architect-engineer contracts.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 48 Federal Acquisition Regulations System 2 2014-10-01 2014-10-01 false Construction and architect-engineer contracts. 53.236 Section 53.236 Federal Acquisition Regulations System FEDERAL ACQUISITION...-engineer contracts. ...

  9. 48 CFR 53.236 - Construction and architect-engineer contracts.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 48 Federal Acquisition Regulations System 2 2010-10-01 2010-10-01 false Construction and architect-engineer contracts. 53.236 Section 53.236 Federal Acquisition Regulations System FEDERAL ACQUISITION...-engineer contracts. ...

  10. 48 CFR 53.236 - Construction and architect-engineer contracts.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 48 Federal Acquisition Regulations System 2 2013-10-01 2013-10-01 false Construction and architect-engineer contracts. 53.236 Section 53.236 Federal Acquisition Regulations System FEDERAL ACQUISITION...-engineer contracts. ...

  11. A hemodynamics model to study the collective behavior of the ventricular-arterial system

    NASA Astrophysics Data System (ADS)

    Lin Wang, Yuh-Ying; Wang, Wei-Kung

    2013-01-01

    Applying principles from complex systems to study the efficacy of integrative therapies has become a new interest in medical research. We aimed to construct a concise model for the ventricular-arterial (VA) system and to provide a systematic method for exploring its overall behavior. The transportation of blood from the heart to the peripheral arterioles via hydraulic pressure forces was described by a multi-rank model. Parts of the VA system that have strong mutual interactions were combined into a single sub system. Sub systems of four different ranks were characterized. We then applied the multi-rank model to analyze the aortic pressure wave generated by the periodic ventricular blood ejection, the renal pressure in response to the input from the VA system, and the blood flowing from the renal artery to its arterioles. Maintaining the pressure distribution along the main arteries and in all of the organs with the lowest possible ventricular input turned out to be the first principle for the operation of an efficient VA system. By this principle, we pointed out the benefit of some arterial structures in mammals, derived specific regulation rules and deduced some fundamental concepts for healing. The justification of the biomechanics in our model that differed greatly from those in the prevailing models was given. We concluded that the oscillatory motion and the pressure pulse of the arterial system can be analyzed as steady states with resonance behaviors and suggested utilizing this model to construct integrative therapies for diseases correlated with abnormality in blood circulation.

  12. Image-guided tissue engineering

    PubMed Central

    Ballyns, Jeffrey J; Bonassar, Lawrence J

    2009-01-01

    Replication of anatomic shape is a significant challenge in developing implants for regenerative medicine. This has lead to significant interest in using medical imaging techniques such as magnetic resonance imaging and computed tomography to design tissue engineered constructs. Implementation of medical imaging and computer aided design in combination with technologies for rapid prototyping of living implants enables the generation of highly reproducible constructs with spatial resolution up to 25 μm. In this paper, we review the medical imaging modalities available and a paradigm for choosing a particular imaging technique. We also present fabrication techniques and methodologies for producing cellular engineered constructs. Finally, we comment on future challenges involved with image guided tissue engineering and efforts to generate engineered constructs ready for implantation. PMID:19583811

  13. 22 CFR 228.39 - Special source rules for construction and engineering services.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... engineering services. 228.39 Section 228.39 Foreign Relations AGENCY FOR INTERNATIONAL DEVELOPMENT RULES ON... engineering services. Advanced developing countries, eligible under Geographic Code 941, which have attained a competitive capability in international markets for construction services or engineering services are not...

  14. 7 CFR 1717.606 - Standard forms of construction contracts, and engineering and architectural services contracts.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... engineering and architectural services contracts. 1717.606 Section 1717.606 Agriculture Regulations of the... Standard forms of construction contracts, and engineering and architectural services contracts. All..., materials, equipment, engineering services, and architectural services, regardless of the source of funding...

  15. 7 CFR 1717.606 - Standard forms of construction contracts, and engineering and architectural services contracts.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... engineering and architectural services contracts. 1717.606 Section 1717.606 Agriculture Regulations of the... Standard forms of construction contracts, and engineering and architectural services contracts. All..., materials, equipment, engineering services, and architectural services, regardless of the source of funding...

  16. 7 CFR 1717.606 - Standard forms of construction contracts, and engineering and architectural services contracts.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... engineering and architectural services contracts. 1717.606 Section 1717.606 Agriculture Regulations of the... Standard forms of construction contracts, and engineering and architectural services contracts. All..., materials, equipment, engineering services, and architectural services, regardless of the source of funding...

  17. 7 CFR 1717.606 - Standard forms of construction contracts, and engineering and architectural services contracts.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... engineering and architectural services contracts. 1717.606 Section 1717.606 Agriculture Regulations of the... Standard forms of construction contracts, and engineering and architectural services contracts. All..., materials, equipment, engineering services, and architectural services, regardless of the source of funding...

  18. 7 CFR 1717.606 - Standard forms of construction contracts, and engineering and architectural services contracts.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... engineering and architectural services contracts. 1717.606 Section 1717.606 Agriculture Regulations of the... Standard forms of construction contracts, and engineering and architectural services contracts. All..., materials, equipment, engineering services, and architectural services, regardless of the source of funding...

  19. 22 CFR 228.39 - Special source rules for construction and engineering services.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... engineering services. 228.39 Section 228.39 Foreign Relations AGENCY FOR INTERNATIONAL DEVELOPMENT RULES ON... engineering services. Advanced developing countries, eligible under Geographic Code 941, which have attained a competitive capability in international markets for construction services or engineering services are not...

  20. Dollar Summary of Federal Supply Classification and Service Category by Company, FY83, Part 5 (N065-W059).

    DTIC Science & Technology

    1983-01-01

    BLDGS 1,269 PHILLIPS SWAGER ASSOCIATES ILLINOIS ARMY A/E CONSTRUCTION /ADMIN 9 SVC BLDGS 174 QUINLIVIAN PIERIK KRAUSE ROBSON JV NEW YORK NAVY A/E...CONSTRUCTION /AIRFIELD & MSL FAC RANCORN WILDMAN & KRAUSE VIRGINIA NAVY A/E CONSTRUCTION /AIRFIELD & MSL FAC REED ALONZO B MASS ARMY A/E CONSTRUCTION...ARCHITECT/ENGINEER - GENERAL CONTRACTOR TOTAL OUADRA ENGINEERING INC ALASKA OCE ARCHITECT/ENGINEER - GENERAL QUINLIVAN PIERIK & KRAUSE MASS ARMY ARCHITECT

  1. Engineer at Lehigh University Campaigns for More Construction Research.

    ERIC Educational Resources Information Center

    Wheeler, David L.

    1987-01-01

    A civil engineering professor would like to see civil engineers spend less time looking at broken structures and more time testing construction materials, and has founded a research center for that purpose. (MSE)

  2. Popularizing Geological Education among Civil Engineering Students

    ERIC Educational Resources Information Center

    Chen, Xiang-jun; Zhou, Ying

    2012-01-01

    The sustainable development of an economy and a society cannot be realized without the help of modern geoscience. Engineering geology knowledge is necessary on a civil engineering construction site to ensure the construction work goes smoothly. This paper first discusses the importance of geoscience, especially the study of engineering geology.…

  3. 76 FR 28333 - Electric Engineering, Architectural Services, Design Policies and Construction Standards

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-05-17

    ... CFR Parts 1724 and 1726 RIN 0572-AC20 Electric Engineering, Architectural Services, Design Policies... standard forms of contracts promulgated by RUS for construction, procurement, engineering services and... XVII of title 7 of the Code of Federal Regulations as follows: PART 1724--ELECTRIC ENGINEERING...

  4. 30 CFR 36.25 - Engine exhaust system.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 30 Mineral Resources 1 2014-07-01 2014-07-01 false Engine exhaust system. 36.25 Section 36.25... EQUIPMENT Construction and Design Requirements § 36.25 Engine exhaust system. (a) Construction. The exhaust system of the engine shall be designed to withstand an internal pressure equal to 4 times the maximum...

  5. Automated construction of arterial and venous trees in retinal images.

    PubMed

    Hu, Qiao; Abràmoff, Michael D; Garvin, Mona K

    2015-10-01

    While many approaches exist to segment retinal vessels in fundus photographs, only a limited number focus on the construction and disambiguation of arterial and venous trees. Previous approaches are local and/or greedy in nature, making them susceptible to errors or limiting their applicability to large vessels. We propose a more global framework to generate arteriovenous trees in retinal images, given a vessel segmentation. In particular, our approach consists of three stages. The first stage is to generate an overconnected vessel network, named the vessel potential connectivity map (VPCM), consisting of vessel segments and the potential connectivity between them. The second stage is to disambiguate the VPCM into multiple anatomical trees, using a graph-based metaheuristic algorithm. The third stage is to classify these trees into arterial or venous (A/V) trees. We evaluated our approach with a ground truth built based on a public database, showing a pixel-wise classification accuracy of 88.15% using a manual vessel segmentation as input, and 86.11% using an automatic vessel segmentation as input.

  6. A Knowledge Engineering Approach to Analysis and Evaluation of Construction Schedules

    DTIC Science & Technology

    1990-02-01

    software engineering discipline focusing on constructing KBSs. It is an incremental and cyclical process that requires the interaction of a domain expert(s...the U.S. Army Coips of Engineers ; and (3) the project management software developer, represented by Pinnell Engineering , Inc. Since the primary...the programming skills necessary to convert the raw knowledge intn a form a computer can understand. knowledge engineering : The software engineering

  7. Relative Economy of Different Methods of Airplane Construction

    NASA Technical Reports Server (NTRS)

    Herrmann, H

    1931-01-01

    A comparison of the relative economy of airplane construction shows that monoplanes are cheaper than biplanes; that all-metal construction is much more expensive than mixed construction; that multi-engine airplanes are more expensive than single-engine types of the same carrying capacity and speed;that the cost of airplanes is materially reduced by increasing their size without increasing the number of engines. The greatest economy usually coincides with the best aerodynamic and static conditions and the cost is always increased by safety requirements.

  8. Development of a construction engineering manpower system for Georgia DOT.

    DOT National Transportation Integrated Search

    1994-07-01

    The objective of this special research study was to develop a construction engineering manpower management system based primarily on construction dollars and to determine if this type of system will be adequate for the GDOT.

  9. Engineering a lunar photolithoautotroph to thrive on the moon - life or simulacrum?

    NASA Astrophysics Data System (ADS)

    Ellery, A. A.

    2018-07-01

    Recent work in developing self-replicating machines has approached the problem as an engineering problem, using engineering materials and methods to implement an engineering analogue of a hitherto uniquely biological function. The question is - can anything be learned that might be relevant to an astrobiological context in which the problem is to determine the general form of biology independent of the Earth. Compared with other non-terrestrial biology disciplines, engineered life is more demanding. Engineering a self-replicating machine tackles real environments unlike artificial life which avoids the problem of physical instantiation altogether by examining software models. Engineering a self-replicating machine is also more demanding than synthetic biology as no library of functional components exists. Everything must be constructed de novo. Biological systems already have the capacity to self-replicate but no engineered machine has yet been constructed with the same ability - this is our primary goal. On the basis of the von Neumann analysis of self-replication, self-replication is a by-product of universal construction capability - a universal constructor is a machine that can construct anything (in a functional sense) given the appropriate instructions (DNA/RNA), energy (ATP) and materials (food). In the biological cell, the universal construction mechanism is the ribosome. The ribosome is a biological assembly line for constructing proteins while DNA constitutes a design specification. For a photoautotroph, the energy source is ambient and the food is inorganic. We submit that engineering a self-replicating machine opens up new areas of astrobiology to be explored in the limits of life.

  10. Intracranial arteries in individuals with the elastin gene hemideletion of Williams syndrome.

    PubMed

    Wint, D P; Butman, J A; Masdeu, J C; Meyer-Lindenberg, A; Mervis, C B; Sarpal, D; Morris, C A; Berman, K F

    2014-01-01

    Williams syndrome, a rare genetic disorder with a striking neurobehavioral profile characterized by extreme sociability and impaired visuospatial construction abilities, is caused by a hemideletion that includes the elastin gene, resulting in frequent supravavular aortic stenosis and other stenotic arterial lesions. Strokes have been reported in Williams syndrome. Although the extracranial carotid artery has been studied in a sample of patients with Williams syndrome, proximal intracranial arteries have not. Using MRA, we studied the intracranial vessels in 27 participants: 14 patients with Williams syndrome (age range, 18-44 years; mean age, 27.3 ± 9.1; 43% women) and 13 healthy control participants with similar age and sex distribution (age range, 22-52 years; mean age, 33.4 ± 7.6; 46% women). All participants with Williams syndrome had hemideletions of the elastin gene. Blinded to group allocation or to any other clinical data, a neuroradiologist determined the presence of intracranial vascular changes in the 2 groups. The Williams syndrome group and the healthy control group had similar patency of the proximal intracranial arteries, including the internal carotid and vertebral arteries; basilar artery; and stem and proximal branches of the anterior cerebral artery, MCA, and posterior cerebral arteries. The postcommunicating segment of the anterior cerebral artery was longer in the Williams syndrome group. Despite the elastin haploinsufficiency, the proximal intracranial arteries in Williams syndrome preserve normal patency.

  11. Savannah River Plant engineering, design, and construction history of ``S`` projects and other work, January 1961--December 1964. Volume 2

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Not Available

    1970-03-01

    The work described in this volume of ``S`` Projects History is an extension of the type of work described in Volume I. E.I. du Pont de flemours & Company had entered into Contract AT (07-2)-l with the United States Atomic Energy Commission to develop, design, construct, install, and operate facilities to produce heavy water, fissionable materials, and related products. Under this contract,, Du Pont constructed and operated the Savannah River Plant. The engineering, design, and construction for most of the larger ``S`` projects was performed by the Engineering DeDartment. For some of the large and many of the smaller projectsmore » the Engineering Department was responsible only for the construction because the Atomic Energy Division (AED) of the Explosives Department handled the other phases. The Engineering Department Costruction Division also performed the physical work for many of the plant work orders. This volume includes a general description of the Du Pont Engineering Department activities pertaining to the engineering, design, and construction of the ``S`` projects at the Savannah River Plant; brief summaries of the projects and principal work requests; and supplementary informaticn on a few subjects in Volume I for which final data was not available at the closing date. Projects and other plant engineering work which were handled entirely by the Explosives Department -- AED are not included in this history.« less

  12. Mountain Plains Learning Experience Guide: Automotive Repair. Course: Engine Repair.

    ERIC Educational Resources Information Center

    Schramm, C.; Osland, Walt

    One of twelve individualized courses included in an automotive repair curriculum, this course covers theory and construction, inspection diagnoses, and service and overhaul of automotive engines. The course is comprised of five units: (1) Fundamentals of Four-Cycle Engines, (2) Engine Construction, (3) Valve Train, (4) Lubricating Systems, and (5)…

  13. 7 CFR 1753.15 - General.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... funds, postloan architectural or engineering services shall be obtained if (1) the construction cost... TELECOMMUNICATIONS SYSTEM CONSTRUCTION POLICIES AND PROCEDURES Engineering Services § 1753.15 General. (a)(1) The standard RUS loan documents contain provisions regarding engineering and architectural services performed...

  14. 7 CFR 1753.15 - General.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... funds, postloan architectural or engineering services shall be obtained if (1) the construction cost... TELECOMMUNICATIONS SYSTEM CONSTRUCTION POLICIES AND PROCEDURES Engineering Services § 1753.15 General. (a)(1) The standard RUS loan documents contain provisions regarding engineering and architectural services performed...

  15. 7 CFR 1753.15 - General.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... funds, postloan architectural or engineering services shall be obtained if (1) the construction cost... TELECOMMUNICATIONS SYSTEM CONSTRUCTION POLICIES AND PROCEDURES Engineering Services § 1753.15 General. (a)(1) The standard RUS loan documents contain provisions regarding engineering and architectural services performed...

  16. 7 CFR 1753.15 - General.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... funds, postloan architectural or engineering services shall be obtained if (1) the construction cost... TELECOMMUNICATIONS SYSTEM CONSTRUCTION POLICIES AND PROCEDURES Engineering Services § 1753.15 General. (a)(1) The standard RUS loan documents contain provisions regarding engineering and architectural services performed...

  17. 7 CFR 1753.15 - General.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... funds, postloan architectural or engineering services shall be obtained if (1) the construction cost... TELECOMMUNICATIONS SYSTEM CONSTRUCTION POLICIES AND PROCEDURES Engineering Services § 1753.15 General. (a)(1) The standard RUS loan documents contain provisions regarding engineering and architectural services performed...

  18. Evaluating the Construct-Coverage of the e-rater[R] Scoring Engine. Research Report. ETS RR-09-01

    ERIC Educational Resources Information Center

    Quinlan, Thomas; Higgins, Derrick; Wolff, Susanne

    2009-01-01

    This report evaluates the construct coverage of the e-rater[R[ scoring engine. The matter of construct coverage depends on whether one defines writing skill, in terms of process or product. Originally, the e-rater engine consisted of a large set of components with a proven ability to predict human holistic scores. By organizing these capabilities…

  19. Compendium of Administrators of Land Use and Related Programs. Revision

    DTIC Science & Technology

    1982-09-01

    construction engineering research laboratory Army Nation Unitad Stoic«» Army ^ n * Technical Report N-40 (Revised) September 19 82...CONTRACT OR GRANT NUMBER’«) \\ 9. PERFORMING ORGANIZATION NAME AND ADDRESS U.S. ARMY CONSTRUCTION ENGINEERING RESEARCH LABORATORY...Chief of Engineers (OCE), under Project 4A762720A896, "Environmental Quality for Construction and Operation of Military Facilities" Task 04. "Land Use

  20. Promoting Quality in NAVFAC (Naval Facilities Engineering Command) Construction.

    DTIC Science & Technology

    1986-01-01

    experience. Inspector Checklists To assist their field construction engineers, Owens - Corning Fiberglas Corporation, in conjunction with Texas A&M...that developed by Owens - Corning Fiberglas A I Corporation to assist government inspectors to maintain high - quality standards in their construction...105, No. C03 (September 1979), 187-199. Information in a letter to the author from D.R. Eberts, Quality Assurance Engineer, Owens - Corning Fiberglas

  1. Effects of gravitational stress, hypokinesia and hypodynamia on the structure of the vascular bed of the spleen

    NASA Technical Reports Server (NTRS)

    Nesterenko, N. T.

    1980-01-01

    The effects of two extreme factors, hypokinesia and hypodynamia, on spleen vascular beds were studied on 180 male and female albino rats. Vessels were studied by roentgenography, microroentgenography, clearing of sections and histology. Gravity stress yielded construction of all links of arterial bed and of order 5-7 veins. Large intraorganic vein diameters changed significantly but erratically. Hypokinesia in early phases produced pronounced spleen size reduction. Veins and arteries constricted along entire length. Later hypokinetic stages showed arteries still constricted; veins began to dilate from week 4 of hypokinesia. Sinuosity, uneven contours and varicose dilations of walls in large arteries and veins occurred. Abrupt changes in parenchyma, e.g., atrophy of folliculi, narrowing of lumen of central arteries from thickening of muscular wall. After exposure to hypokinesia followed by gravitational stress, pronounced lesions such as deformation of vascular wall, including rupture, in all vessels of the spleen vascular bed.

  2. 48 CFR 836.602-4 - Selection authority.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... CATEGORIES OF CONTRACTING CONSTRUCTION AND ARCHITECT-ENGINEER CONTRACTS Architect-Engineer Services 836.602-4 Selection authority. The Director, Office of Construction and Facilities Management (for Central Office contracts), the Director, Office of Construction Management (for National Cemetery Administration contracts...

  3. 48 CFR 836.602-4 - Selection authority.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... CATEGORIES OF CONTRACTING CONSTRUCTION AND ARCHITECT-ENGINEER CONTRACTS Architect-Engineer Services 836.602-4 Selection authority. The Director, Office of Construction and Facilities Management (for Central Office contracts), the Director, Office of Construction Management (for National Cemetery Administration contracts...

  4. 48 CFR 836.602-4 - Selection authority.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... CATEGORIES OF CONTRACTING CONSTRUCTION AND ARCHITECT-ENGINEER CONTRACTS Architect-Engineer Services 836.602-4 Selection authority. The Director, Office of Construction and Facilities Management (for Central Office contracts), the Director, Office of Construction Management (for National Cemetery Administration contracts...

  5. 48 CFR 836.602-4 - Selection authority.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... CATEGORIES OF CONTRACTING CONSTRUCTION AND ARCHITECT-ENGINEER CONTRACTS Architect-Engineer Services 836.602-4 Selection authority. The Director, Office of Construction and Facilities Management (for Central Office contracts), the Director, Office of Construction Management (for National Cemetery Administration contracts...

  6. Arterial α2-Na+ pump expression influences blood pressure: lessons from novel, genetically engineered smooth muscle-specific α2 mice.

    PubMed

    Chen, Ling; Song, Hong; Wang, Youhua; Lee, Jane C; Kotlikoff, Michael I; Pritchard, Tracy J; Paul, Richard J; Zhang, Jin; Blaustein, Mordecai P

    2015-09-01

    Arterial myocytes express α1-catalytic subunit isoform Na(+) pumps (75-80% of total), which are ouabain resistant in rodents, and high ouabain affinity α2-Na(+) pumps. Mice with globally reduced α2-pumps (but not α1-pumps), mice with mutant ouabain-resistant α2-pumps, and mice with a smooth muscle (SM)-specific α2-transgene (α2 (SM-Tg)) that induces overexpression all have altered blood pressure (BP) phenotypes. We generated α2 (SM-DN) mice with SM-specific α2 (not α1) reduction (>50%) using nonfunctional dominant negative (DN) α2. We compared α2 (SM-DN) and α2 (SM-Tg) mice to controls to determine how arterial SM α2-pumps affect vasoconstriction and BP. α2 (SM-DN) mice had elevated basal mean BP (mean BP by telemetry: 117 ± 4 vs. 106 ± 1 mmHg, n = 7/7, P < 0.01) and enhanced BP responses to chronic ANG II infusion (240 ng·kg(-1)·min(-1)) and high (6%) NaCl. Several arterial Ca(2+) transporters, including Na(+)/Ca(2+) exchanger 1 (NCX1) and sarcoplasmic reticulum and plasma membrane Ca(2+) pumps [sarco(endo)plasmic reticulum Ca(2+)-ATPase 2 (SERCA2) and plasma membrane Ca(2+)-ATPase 1 (PMCA1)], were also reduced (>50%). α2 (SM-DN) mouse isolated small arteries had reduced myogenic reactivity, perhaps because of reduced Ca(2+) transporter expression. In contrast, α2 (SM-Tg) mouse aortas overexpressed α2 (>2-fold), NCX1, SERCA2, and PMCA1 (43). α2 (SM-Tg) mice had reduced basal mean BP (104 ± 1 vs. 109 ± 2 mmHg, n = 15/9, P < 0.02) and attenuated BP responses to chronic ANG II (300-400 ng·kg(-1)·min(-1)) with or without 2% NaCl but normal myogenic reactivity. NCX1 expression was inversely related to basal BP in SM-α2 engineered mice but was directly related in SM-NCX1 engineered mice. NCX1, which usually mediates arterial Ca(2+) entry, and α2-Na(+) pumps colocalize at plasma membrane-sarcoplasmic reticulum junctions and functionally couple via the local Na(+) gradient to help regulate cell Ca(2+). Altered Ca(2+) transporter expression in SM-α2 engineered mice apparently compensates to minimize Ca(2+) overload (α2 (SM-DN)) or depletion (α2 (SM-Tg)) and attenuate BP changes. In contrast, Ca(2+) transporter upregulation, observed in many rodent hypertension models, should enhance Ca(2+) entry and signaling and contribute significantly to BP elevation. Copyright © 2015 the American Physiological Society.

  7. 25 CFR 900.122 - What does an Indian tribe or tribal organization do if it wants to secure a construction contract?

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... UNDER THE INDIAN SELF-DETERMINATION AND EDUCATION ASSISTANCE ACT Construction § 900.122 What does an... information available about the construction project, including construction drawings, maps, engineering... tribal organization to review all plans, specifications, engineering reports, cost estimates, and other...

  8. A Cost-Minimization Analysis of Tissue-Engineered Constructs for Corneal Endothelial Transplantation

    PubMed Central

    Tan, Tien-En; Peh, Gary S. L.; George, Benjamin L.; Cajucom-Uy, Howard Y.; Dong, Di; Finkelstein, Eric A.; Mehta, Jodhbir S.

    2014-01-01

    Corneal endothelial transplantation or endothelial keratoplasty has become the preferred choice of transplantation for patients with corneal blindness due to endothelial dysfunction. Currently, there is a worldwide shortage of transplantable tissue, and demand is expected to increase further with aging populations. Tissue-engineered alternatives are being developed, and are likely to be available soon. However, the cost of these constructs may impair their widespread use. A cost-minimization analysis comparing tissue-engineered constructs to donor tissue procured from eye banks for endothelial keratoplasty was performed. Both initial investment costs and recurring costs were considered in the analysis to arrive at a final tissue cost per transplant. The clinical outcomes of endothelial keratoplasty with tissue-engineered constructs and with donor tissue procured from eye banks were assumed to be equivalent. One-way and probabilistic sensitivity analyses were performed to simulate various possible scenarios, and to determine the robustness of the results. A tissue engineering strategy was cheaper in both investment cost and recurring cost. Tissue-engineered constructs for endothelial keratoplasty could be produced at a cost of US$880 per transplant. In contrast, utilizing donor tissue procured from eye banks for endothelial keratoplasty required US$3,710 per transplant. Sensitivity analyses performed further support the results of this cost-minimization analysis across a wide range of possible scenarios. The use of tissue-engineered constructs for endothelial keratoplasty could potentially increase the supply of transplantable tissue and bring the costs of corneal endothelial transplantation down, making this intervention accessible to a larger group of patients. Tissue-engineering strategies for corneal epithelial constructs or other tissue types, such as pancreatic islet cells, should also be subject to similar pharmacoeconomic analyses. PMID:24949869

  9. A cost-minimization analysis of tissue-engineered constructs for corneal endothelial transplantation.

    PubMed

    Tan, Tien-En; Peh, Gary S L; George, Benjamin L; Cajucom-Uy, Howard Y; Dong, Di; Finkelstein, Eric A; Mehta, Jodhbir S

    2014-01-01

    Corneal endothelial transplantation or endothelial keratoplasty has become the preferred choice of transplantation for patients with corneal blindness due to endothelial dysfunction. Currently, there is a worldwide shortage of transplantable tissue, and demand is expected to increase further with aging populations. Tissue-engineered alternatives are being developed, and are likely to be available soon. However, the cost of these constructs may impair their widespread use. A cost-minimization analysis comparing tissue-engineered constructs to donor tissue procured from eye banks for endothelial keratoplasty was performed. Both initial investment costs and recurring costs were considered in the analysis to arrive at a final tissue cost per transplant. The clinical outcomes of endothelial keratoplasty with tissue-engineered constructs and with donor tissue procured from eye banks were assumed to be equivalent. One-way and probabilistic sensitivity analyses were performed to simulate various possible scenarios, and to determine the robustness of the results. A tissue engineering strategy was cheaper in both investment cost and recurring cost. Tissue-engineered constructs for endothelial keratoplasty could be produced at a cost of US$880 per transplant. In contrast, utilizing donor tissue procured from eye banks for endothelial keratoplasty required US$3,710 per transplant. Sensitivity analyses performed further support the results of this cost-minimization analysis across a wide range of possible scenarios. The use of tissue-engineered constructs for endothelial keratoplasty could potentially increase the supply of transplantable tissue and bring the costs of corneal endothelial transplantation down, making this intervention accessible to a larger group of patients. Tissue-engineering strategies for corneal epithelial constructs or other tissue types, such as pancreatic islet cells, should also be subject to similar pharmacoeconomic analyses.

  10. 23 CFR 661.3 - Who must comply with this regulation?

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... authorities must comply to participate in the IRRBP by applying for preliminary engineering (PE), construction, and construction engineering (CE) activities for the replacement or rehabilitation of structurally....3 Highways FEDERAL HIGHWAY ADMINISTRATION, DEPARTMENT OF TRANSPORTATION ENGINEERING AND TRAFFIC...

  11. 23 CFR 661.3 - Who must comply with this regulation?

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... authorities must comply to participate in the IRRBP by applying for preliminary engineering (PE), construction, and construction engineering (CE) activities for the replacement or rehabilitation of structurally....3 Highways FEDERAL HIGHWAY ADMINISTRATION, DEPARTMENT OF TRANSPORTATION ENGINEERING AND TRAFFIC...

  12. 23 CFR 661.3 - Who must comply with this regulation?

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... authorities must comply to participate in the IRRBP by applying for preliminary engineering (PE), construction, and construction engineering (CE) activities for the replacement or rehabilitation of structurally....3 Highways FEDERAL HIGHWAY ADMINISTRATION, DEPARTMENT OF TRANSPORTATION ENGINEERING AND TRAFFIC...

  13. 23 CFR 661.3 - Who must comply with this regulation?

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... authorities must comply to participate in the IRRBP by applying for preliminary engineering (PE), construction, and construction engineering (CE) activities for the replacement or rehabilitation of structurally....3 Highways FEDERAL HIGHWAY ADMINISTRATION, DEPARTMENT OF TRANSPORTATION ENGINEERING AND TRAFFIC...

  14. 23 CFR 661.3 - Who must comply with this regulation?

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... authorities must comply to participate in the IRRBP by applying for preliminary engineering (PE), construction, and construction engineering (CE) activities for the replacement or rehabilitation of structurally....3 Highways FEDERAL HIGHWAY ADMINISTRATION, DEPARTMENT OF TRANSPORTATION ENGINEERING AND TRAFFIC...

  15. Pulse wave analysis in a 180-degree curved artery model: Implications under physiological and non-physiological inflows

    NASA Astrophysics Data System (ADS)

    Bulusu, Kartik V.; Plesniak, Michael W.

    2013-11-01

    Systolic and diastolic blood pressures, pulse pressures, and left ventricular hypertrophy contribute to cardiovascular risks. Increase of arterial stiffness due to aging and hypertension is an important factor in cardiovascular, chronic kidney and end-stage-renal-diseases. Pulse wave analysis (PWA) based on arterial pressure wave characteristics, is well established in clinical practice for evaluation of arterial distensibility and hypertension. The objective of our exploratory study in a rigid 180-degree curved artery model was to evaluate arterial pressure waveforms. Bend upstream conditions were measured using a two-component, two-dimensional, particle image velocimeter (2C-2D PIV). An ultrasonic transit-time flow meter and a catheter with a MEMS-based solid state pressure sensor, capable of measuring up to 20 harmonics of the observed pressure waveform, monitored flow conditions downstream of the bend. Our novel continuous wavelet transform algorithm (PIVlet 1.2), in addition to detecting coherent secondary flow structures is used to evaluate arterial pulse wave characteristics subjected to physiological and non-physiological inflows. Results of this study will elucidate the utility of wavelet transforms in arterial function evaluation and pulse wave speed. Supported by NSF Grant No. CBET- 0828903 and GW Center for Biomimetics and Bioinspired Engineering.

  16. UltraPulse--simulating a human arterial pulse with focussed airborne ultrasound.

    PubMed

    Hung, G M Y; John, N W; Hancock, C; Gould, D A; Hoshi, T

    2013-01-01

    Medical simulators provide a risk-free environment for trainee doctors to practice and improve their skills. UltraPulse is a new tactile system designed to utilise focussed airborne ultrasound to mimic a pulsation effect such as that of a human arterial pulse. In this paper, we focus on the construction of the haptics component, which can later be integrated into a variety of medical procedure training simulators.

  17. KSC-2012-6405

    NASA Image and Video Library

    2012-09-20

    CAPE CANAVERAL, Fla. -- At NASA’s Kennedy Space Center in Florida, a groundbreaking was held to mark the start of construction on the Antenna Test Bed Array for the Ka-Band Objects Observation and Monitoring, or Ka-BOOM system. Using ceremonial shovels to mark the site, from left are Michael Le, lead design engineer and construction manager Sue Vingris, Cape Design Engineer Co. project manager Kannan Rengarajan, chief executive officer of Cape Design Engineer Co. Lutfi Mized, president of Cape Design Engineer Co. David Roelandt, construction site superintendent with Cape Design Engineer Co. Marc Seibert, NASA project manager Michael Miller, NASA project manager Peter Aragona, KSC’s Electromagnetic Lab manager Stacy Hopper, KSCs master planning supervisor Dr. Bary Geldzabler, NASA chief scientist and KSC’s Chief Technologist Karen Thompson. The construction site is near the former Vertical Processing Facility, which has been demolished. Workers will begin construction on the pile foundations for the 40-foot-diameter dish antenna arrays and their associated utilities, and prepare the site for the operations command center facility. Photo credit: NASA/Charisse Nahser

  18. KSC-2012-6404

    NASA Image and Video Library

    2012-09-20

    CAPE CANAVERAL, Fla. -- At NASA’s Kennedy Space Center in Florida, a groundbreaking was held to mark the start of construction on the Antenna Test Bed Array for the Ka-Band Objects Observation and Monitoring, or Ka-BOOM system. Holding ceremonial shovels, from left are Michael Le, lead design engineer and construction manager Sue Vingris, Cape Design Engineer Co. project manager Kannan Rengarajan, chief executive officer of Cape Design Engineer Co. Lutfi Mized, president of Cape Design Engineer Co. David Roelandt, construction site superintendent with Cape Design Engineer Co. Marc Seibert, NASA project manager Michael Miller, NASA project manager Peter Aragona, KSC’s Electromagnetic Lab manager Stacy Hopper, KSCs master planning supervisor Dr. Bary Geldzabler, NASA chief scientist and KSC’s Chief Technologist Karen Thompson. The construction site is near the former Vertical Processing Facility, which has been demolished. Workers will begin construction on the pile foundations for the 40-foot-diameter dish antenna arrays and their associated utilities, and prepare the site for the operations command center facility. Photo credit: NASA/Charisse Nahser

  19. RESEARCH AND DESIGN ABOUT VERSATILE 3D-CAD ENGINE FOR CONSTRUCTION

    NASA Astrophysics Data System (ADS)

    Tanaka, Shigenori; Kubota, Satoshi; Kitagawa, Etsuji; Monobe, Kantaro; Nakamura, Kenji

    In the construction field of Japan, it is an important subject to build the environment where 3D-CAD data is used for CALS/EC, information construction, and an improvement in productivity. However, in the construction field, 3D-CAD software does not exist under the present circumstances. Then, in order to support development of domestic 3D-CAD software, it is required to develop a 3D-CAD engine. In this research, in order to familiarize the 3D-CAD software at low cost and quickly and build the environment where the 3D-CAD software is utilizable, investigation for designing a 3D-CAD engine is proposed. The target for investigation are the use scene of 3D-CAD, the seeds which accompany 3D-CAD, a standardization trend, existing products, IT component engineering. Based on results of the investigation, the functional requirements for the 3D-CAD engine for the construction field were concluded.

  20. Multimedia techniques for construction education and training : final report.

    DOT National Transportation Integrated Search

    2017-02-01

    The current profession of civil engineering often focuses education and training on code compliance rather than constructability and construction techniques. Also, it is well accepted that it takes a decade or more for engineers to develop a high-lev...

  1. Rubber modified concrete (METRO RUMAC) Evaluation : N. Marine Drive in Portland, Oregon , S.E. Stark Street in Gresham, Oregon : construction report.

    DOT National Transportation Integrated Search

    1992-11-01

    This report covers the construction in 1991 of two test pavements using asphalt modified crumb rubber form scrap tires. The pavements are on arterial roadways in the Portland, Oregon metropolitan area. : Both test pavements use a dense-graded rubber ...

  2. Cryopreservation of human vascular umbilical cord cells under good manufacturing practice conditions for future cell banks

    PubMed Central

    2012-01-01

    Background In vitro fabricated tissue engineered vascular constructs could provide an alternative to conventional substitutes. A crucial factor for tissue engineering of vascular constructs is an appropriate cell source. Vascular cells from the human umbilical cord can be directly isolated and cryopreserved until needed. Currently no cell bank for human vascular cells is available. Therefore, the establishment of a future human vascular cell bank conforming to good manufacturing practice (GMP) conditions is desirable for therapeutic applications such as tissue engineered cardiovascular constructs. Materials and methods A fundamental step was the adaption of conventional research and development starting materials to GMP compliant starting materials. Human umbilical cord artery derived cells (HUCAC) and human umbilical vein endothelial cells (HUVEC) were isolated, cultivated, cryopreserved (short- and long-term) directly after primary culture and recultivated subsequently. Cell viability, expression of cellular markers and proliferation potential of fresh and cryopreserved cells were studied using trypan blue staining, flow cytometry analysis, immunofluorescence staining and proliferation assays. Statistical analyses were performed using Student’s t-test. Results Sufficient numbers of isolated cells with acceptable viabilities and homogenous expression of cellular markers confirmed that the isolation procedure was successful using GMP compliant starting materials. The influence of cryopreservation was marginal, because cryopreserved cells mostly maintain phenotypic and functional characteristics similar to those of fresh cells. Phenotypic studies revealed that fresh cultivated and cryopreserved HUCAC were positive for alpha smooth muscle actin, CD90, CD105, CD73, CD29, CD44, CD166 and negative for smoothelin. HUVEC expressed CD31, CD146, CD105 and CD144 but not alpha smooth muscle actin. Functional analysis demonstrated acceptable viability and sufficient proliferation properties of cryopreserved HUCAC and HUVEC. Conclusion Adaptation of cell isolation, cultivation and cryopreservation to GMP compliant starting materials was successful. Cryopreservation did not influence cell properties with lasting impact, confirming that the application of vascular cells from the human umbilical cord is feasible for cell banking. A specific cellular marker expression profile was established for HUCAC and HUVEC using flow cytometry analysis, applicable as a GMP compliant quality control. Use of these cells for the future fabrication of advanced therapy medicinal products GMP conditions are required by the regulatory authority. PMID:22591741

  3. Metabolic engineering of Escherichia coli for the production of phenylpyruvate derivatives.

    PubMed

    Liu, Shuang Ping; Zhang, Liang; Mao, Jian; Ding, Zhong Yang; Shi, Gui Yang

    2015-11-01

    Phenylpyruvate derivatives (PPD), such as phenylpropanoids, DL-phenylglycine, dl-phenylalanine, and styrene, are biosynthesized using phenylpyruvate as the precursor. They are widely used in human health and nutrition products. Recently, metabolic engineering provides effective strategies to develop PPD producers. Based on phenylpyruvate-producing chassis, genetically defined PPD producers have been successfully constructed. In this work, the most recent information on genetics and on the molecular mechanisms regulating phenylpyruvate synthesis pathways in Escherichia coli are summarized, and the engineering strategies to construct the PPD producers are also discussed. The enzymes and pathways are proposed for PPD-producer constructions, and potential difficulties in strain construction are also identified and discussed. With respect to recent advances in synthetic biology, future strategies to construct efficiently producers are discussed. Copyright © 2015 International Metabolic Engineering Society. Published by Elsevier Inc. All rights reserved.

  4. Engineering cartilage or endochondral bone: a comparison of different naturally derived hydrogels.

    PubMed

    Sheehy, Eamon J; Mesallati, Tariq; Vinardell, Tatiana; Kelly, Daniel J

    2015-02-01

    Cartilaginous tissues engineered using mesenchymal stem cells (MSCs) have been shown to generate bone in vivo by executing an endochondral programme. This may hinder the use of MSCs for articular cartilage regeneration, but opens the possibility of using engineered cartilaginous tissues for large bone defect repair. Hydrogels may be an attractive tool in the scaling-up of such tissue engineered grafts for endochondral bone regeneration. In this study, we compared the capacity of different naturally derived hydrogels (alginate, chitosan and fibrin) to support chondrogenesis and hypertrophy of MSCs in vitro and endochondral ossification in vivo. In vitro, alginate and chitosan constructs accumulated the highest levels of sulfated glycosaminoglycan (sGAG), with chitosan constructs synthesizing the highest levels of collagen. Alginate and fibrin constructs supported the greatest degree of calcium accumulation, though only fibrin constructs calcified homogeneously. In vivo, chitosan constructs facilitated neither vascularization nor endochondral ossification, and also retained the greatest amount of sGAG, suggesting it to be a more suitable material for the engineering of articular cartilage. Both alginate and fibrin constructs facilitated vascularization and endochondral bone formation as well as the development of a bone marrow environment. Alginate constructs accumulated significantly more mineral and supported greater bone formation in central regions of the engineered tissue. In conclusion, this study demonstrates the capacity of chitosan hydrogels to promote and better maintain a chondrogenic phenotype in MSCs and highlights the potential of utilizing alginate hydrogels for MSC-based endochondral bone tissue engineering applications. Copyright © 2014 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.

  5. Nuclear Engineering Technologists in the Nuclear Power Era

    ERIC Educational Resources Information Center

    Wang, C. H.; And Others

    1974-01-01

    Describes manpower needs in nuclear engineering in the areas of research and development, architectural engineering and construction supervision, power reactor operations, and regulatory tasks. Outlines a suitable curriculum to prepare students for the tasks related to construction and operation of power reactors. (GS)

  6. Engineered phages for electronics.

    PubMed

    Cui, Yue

    2016-11-15

    Phages are traditionally widely studied in biology and chemistry. In recent years, engineered phages have attracted significant attentions for functionalization or construction of electronic devices, due to their specific binding, catalytic, nucleating or electronic properties. To apply the engineered phages in electronics, these are a number of interesting questions: how to engineer phages for electronics? How are the engineered phages characterized? How to assemble materials with engineered phages? How are the engineered phages micro or nanopatterned? What are the strategies to construct electronics devices with engineered phages? This review will highlight the early attempts to address these questions and explore the fundamental and practical aspects of engineered phages in electronics, including the approaches for selection or expression of specific peptides on phage coat proteins, characterization of engineered phages in electronics, assembly of electronic materials, patterning of engineered phages, and construction of electronic devices. It provides the methodologies and opens up ex-cit-ing op-por-tu-ni-ties for the development of a variety of new electronic materials and devices based on engineered phages for future applications. Copyright © 2016 Elsevier B.V. All rights reserved.

  7. 48 CFR 936.202-70 - Specifications charges.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... payments, the invitations for bids should so state, and the architect-engineer or construction management... CATEGORIES OF CONTRACTING CONSTRUCTION AND ARCHITECT-ENGINEER CONTRACTS Special Aspects of Contracting for Construction 936.202-70 Specifications charges. (a) To support all invitations for bids, plans and...

  8. 48 CFR 936.202-70 - Specifications charges.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... payments, the invitations for bids should so state, and the architect-engineer or construction management... CATEGORIES OF CONTRACTING CONSTRUCTION AND ARCHITECT-ENGINEER CONTRACTS Special Aspects of Contracting for Construction 936.202-70 Specifications charges. (a) To support all invitations for bids, plans and...

  9. 48 CFR 936.202-70 - Specifications charges.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... payments, the invitations for bids should so state, and the architect-engineer or construction management... CATEGORIES OF CONTRACTING CONSTRUCTION AND ARCHITECT-ENGINEER CONTRACTS Special Aspects of Contracting for Construction 936.202-70 Specifications charges. (a) To support all invitations for bids, plans and...

  10. 48 CFR 936.202-70 - Specifications charges.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... payments, the invitations for bids should so state, and the architect-engineer or construction management... CATEGORIES OF CONTRACTING CONSTRUCTION AND ARCHITECT-ENGINEER CONTRACTS Special Aspects of Contracting for Construction 936.202-70 Specifications charges. (a) To support all invitations for bids, plans and...

  11. 7 CFR 1726.404 - Non-site specific construction contract closeout.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... UTILITIES SERVICE, DEPARTMENT OF AGRICULTURE ELECTRIC SYSTEM CONSTRUCTION POLICIES AND PROCEDURES Contract... equipment is supplied under a construction contract, the borrower (acting through its engineer, if... equipment. The borrower (acting through its engineer, if applicable) will schedule such inspection and...

  12. 7 CFR 1726.404 - Non-site specific construction contract closeout.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... UTILITIES SERVICE, DEPARTMENT OF AGRICULTURE ELECTRIC SYSTEM CONSTRUCTION POLICIES AND PROCEDURES Contract... equipment is supplied under a construction contract, the borrower (acting through its engineer, if... equipment. The borrower (acting through its engineer, if applicable) will schedule such inspection and...

  13. 7 CFR 1726.404 - Non-site specific construction contract closeout.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... UTILITIES SERVICE, DEPARTMENT OF AGRICULTURE ELECTRIC SYSTEM CONSTRUCTION POLICIES AND PROCEDURES Contract... equipment is supplied under a construction contract, the borrower (acting through its engineer, if... equipment. The borrower (acting through its engineer, if applicable) will schedule such inspection and...

  14. 7 CFR 1726.404 - Non-site specific construction contract closeout.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... UTILITIES SERVICE, DEPARTMENT OF AGRICULTURE ELECTRIC SYSTEM CONSTRUCTION POLICIES AND PROCEDURES Contract... equipment is supplied under a construction contract, the borrower (acting through its engineer, if... equipment. The borrower (acting through its engineer, if applicable) will schedule such inspection and...

  15. 7 CFR 1726.404 - Non-site specific construction contract closeout.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... UTILITIES SERVICE, DEPARTMENT OF AGRICULTURE ELECTRIC SYSTEM CONSTRUCTION POLICIES AND PROCEDURES Contract... equipment is supplied under a construction contract, the borrower (acting through its engineer, if... equipment. The borrower (acting through its engineer, if applicable) will schedule such inspection and...

  16. 48 CFR 936.202-70 - Specifications charges.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... payments, the invitations for bids should so state, and the architect-engineer or construction management... CATEGORIES OF CONTRACTING CONSTRUCTION AND ARCHITECT-ENGINEER CONTRACTS Special Aspects of Contracting for Construction 936.202-70 Specifications charges. (a) To support all invitations for bids, plans and...

  17. Safety in Construction Using Virtual Reality (SAVR): A Model for Labor Safety. Working Paper Series WP-022.

    ERIC Educational Resources Information Center

    Hadipriono, Fabian C.; And Others

    An interactive training model called SAVR (Safety in Construction Using Virtual Reality) was developed to train construction students, novice engineers, and construction workers to prevent falls from scaffolding. The model was implemented in a graphics supercomputer, the ONYX Reality Engine2. The SAVR model provides trainees with an immersive,…

  18. 14 CFR 33.11 - Applicability.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... STANDARDS: AIRCRAFT ENGINES Design and Construction; General § 33.11 Applicability. This subpart prescribes the general design and construction requirements for reciprocating and turbine aircraft engines. ...

  19. 14 CFR 33.11 - Applicability.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... STANDARDS: AIRCRAFT ENGINES Design and Construction; General § 33.11 Applicability. This subpart prescribes the general design and construction requirements for reciprocating and turbine aircraft engines. ...

  20. SAE 2018-01-1412 Constructing Engine Maps - Presentation at the April 2018 World Congress

    EPA Pesticide Factsheets

    This presentation describes important factors and approach, along with the process for constructing complete engine maps using engine dynamometer and in-vehicle test data for use in ALPHA or any other full vehicle simulation which performs similar analyses

  1. Cartilage constructs engineered from chondrocytes overexpressing IGF-I improve the repair of osteochondral defects in a rabbit model.

    PubMed

    Madry, H; Kaul, G; Zurakowski, D; Vunjak-Novakovic, G; Cucchiarini, M

    2013-04-16

    Tissue engineering combined with gene therapy is a promising approach for promoting articular cartilage repair. Here, we tested the hypothesis that engineered cartilage with chondrocytes overexpressing a human insulin-like growth factor I (IGF-I) gene can enhance the repair of osteochondral defects, in a manner dependent on the duration of cultivation. Genetically modified chondrocytes were cultured on biodegradable polyglycolic acid scaffolds in dynamic flow rotating bioreactors for either 10 or 28 d. The resulting cartilaginous constructs were implanted into osteochondral defects in rabbit knee joints. After 28 weeks of in vivo implantation, immunoreactivity to ß-gal was detectable in the repair tissue of defects that received lacZ constructs. Engineered cartilaginous constructs based on IGF-I-overexpressing chondrocytes markedly improved osteochondral repair compared with control (lacZ) constructs. Moreover, IGF-I constructs cultivated for 28 d in vitro significantly promoted osteochondral repair vis-à-vis similar constructs cultivated for 10 d, leading to significantly decreased osteoarthritic changes in the cartilage adjacent to the defects. Hence, the combination of spatially defined overexpression of human IGF-I within a tissue-engineered construct and prolonged bioreactor cultivation resulted in most enhanced articular cartilage repair and reduction of osteoarthritic changes in the cartilage adjacent to the defect. Such genetically enhanced tissue engineering provides a versatile tool to evaluate potential therapeutic genes in vivo and to improve our comprehension of the development of the repair tissue within articular cartilage defects. Insights gained with additional exploration using this model may lead to more effective treatment options for acute cartilage defects.

  2. CARTILAGE CONSTRUCTS ENGINEERED FROM CHONDROCYTES OVEREXPRESSING IGF-I IMPROVE THE REPAIR OF OSTEOCHONDRAL DEFECTS IN A RABBIT MODEL

    PubMed Central

    Madry, Henning; Kaul, Gunter; Zurakowski, David; Vunjak-Novakovic, Gordana; Cucchiarini, Magali

    2015-01-01

    Tissue engineering combined with gene therapy is a promising approach for promoting articular cartilage repair. Here, we tested the hypothesis that engineered cartilage with chondrocytes over expressing a human insulin-like growth factor I (IGF-I) gene can enhance the repair of osteochondral defects, in a manner dependent on the duration of cultivation. Genetically modified chondrocytes were cultured on biodegradable polyglycolic acid scaffolds in dynamic flow rotating bioreactors for either 10 or 28 d. The resulting cartilaginous constructs were implanted into osteochondral defects in rabbit knee joints. After 28 weeks of in vivo implantation, immunoreactivity to ß-gal was detectable in the repair tissue of defects that received lacZ constructs. Engineered cartilaginous constructs based on IGF-I-over expressing chondrocytes markedly improved osteochondral repair compared with control (lacZ) constructs. Moreover, IGF-I constructs cultivated for 28 d in vitro significantly promoted osteochondral repair vis-à-vis similar constructs cultivated for 10 d, leading to significantly decreased osteoarthritic changes in the cartilage adjacent to the defects. Hence, the combination of spatially defined overexpression of human IGF-I within a tissue-engineered construct and prolonged bioreactor cultivation resulted in most enhanced articular cartilage repair and reduction of osteoarthritic changes in the cartilage adjacent to the defect. Such genetically enhanced tissue engineering provides a versatile tool to evaluate potential therapeutic genes in vivo and to improve our comprehension of the development of the repair tissue within articular cartilage defects. Insights gained with additional exploration using this model may lead to more effective treatment options for acute cartilage defects. PMID:23588785

  3. 48 CFR 52.248-3 - Value Engineering-Construction.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 48 Federal Acquisition Regulations System 2 2013-10-01 2013-10-01 false Value Engineering....248-3 Value Engineering—Construction. As prescribed in 48.202, insert the following clause: Value Engineering—Construction (OCT 2010) (a) General. The Contractor is encouraged to develop, prepare, and submit...

  4. 48 CFR 52.248-3 - Value Engineering-Construction.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 48 Federal Acquisition Regulations System 2 2014-10-01 2014-10-01 false Value Engineering....248-3 Value Engineering—Construction. As prescribed in 48.202, insert the following clause: Value Engineering—Construction (OCT 2010) (a) General. The Contractor is encouraged to develop, prepare, and submit...

  5. 48 CFR 52.248-3 - Value Engineering-Construction.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 48 Federal Acquisition Regulations System 2 2010-10-01 2010-10-01 false Value Engineering....248-3 Value Engineering—Construction. As prescribed in 48.202, insert the following clause: Value Engineering—Construction (OCT 2010) (a) General. The Contractor is encouraged to develop, prepare, and submit...

  6. 48 CFR 52.248-3 - Value Engineering-Construction.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 48 Federal Acquisition Regulations System 2 2011-10-01 2011-10-01 false Value Engineering....248-3 Value Engineering—Construction. As prescribed in 48.202, insert the following clause: Value Engineering—Construction (OCT 2010) (a) General. The Contractor is encouraged to develop, prepare, and submit...

  7. 48 CFR 52.248-3 - Value Engineering-Construction.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 48 Federal Acquisition Regulations System 2 2012-10-01 2012-10-01 false Value Engineering....248-3 Value Engineering—Construction. As prescribed in 48.202, insert the following clause: Value Engineering—Construction (OCT 2010) (a) General. The Contractor is encouraged to develop, prepare, and submit...

  8. Monitoring sinew contraction during formation of tissue-engineered fibrin-based ligament constructs.

    PubMed

    Paxton, Jennifer Z; Wudebwe, Uchena N G; Wang, Anqi; Woods, Daniel; Grover, Liam M

    2012-08-01

    The ability to study the gross morphological changes occurring during tissue formation is vital to producing tissue-engineered structures of clinically relevant dimensions in vitro. Here, we have used nondestructive methods of digital imaging and optical coherence tomography to monitor the early-stage formation and subsequent maturation of fibrin-based tissue-engineered ligament constructs. In addition, the effect of supplementation with essential promoters of collagen synthesis, ascorbic acid (AA) and proline (P), has been assessed. Contraction of the cell-seeded fibrin gel occurs unevenly within the first 5 days of culture around two fixed anchor points before forming a longitudinal ligament-like construct. AA+P supplementation accelerates gel contraction in the maturation phase of development, producing ligament-like constructs with a higher collagen content and distinct morphology to that of unsupplemented constructs. These studies highlight the importance of being able to control the methods of tissue formation and maturation in vitro to enable the production of tissue-engineered constructs with suitable replacement tissue characteristics for repair of clinical soft-tissue injuries.

  9. 3D Printed Vascular Networks Enhance Viability in High-Volume Perfusion Bioreactor.

    PubMed

    Ball, Owen; Nguyen, Bao-Ngoc B; Placone, Jesse K; Fisher, John P

    2016-12-01

    There is a significant clinical need for engineered bone graft substitutes that can quickly, effectively, and safely repair large segmental bone defects. One emerging field of interest involves the growth of engineered bone tissue in vitro within bioreactors, the most promising of which are perfusion bioreactors. Using bioreactor systems, tissue engineered bone constructs can be fabricated in vitro. However, these engineered constructs lack inherent vasculature and once implanted, quickly develop a necrotic core, where no nutrient exchange occurs. Here, we utilized COMSOL modeling to predict oxygen diffusion gradients throughout aggregated alginate constructs, which allowed for the computer-aided design of printable vascular networks, compatible with any large tissue engineered construct cultured in a perfusion bioreactor. We investigated the effect of 3D printed macroscale vascular networks with various porosities on the viability of human mesenchymal stem cells in vitro, using both gas-permeable, and non-gas permeable bioreactor growth chamber walls. Through the use of 3D printed vascular structures in conjunction with a tubular perfusion system bioreactor, cell viability was found to increase by as much as 50% in the core of these constructs, with in silico modeling predicting construct viability at steady state.

  10. 3D Printed Vascular Networks Enhance Viability in High-Volume Perfusion Bioreactor

    PubMed Central

    Ball, Owen; Nguyen, Bao-Ngoc B.; Placone, Jesse K.; Fisher, John P.

    2016-01-01

    There is a significant clinical need for engineered bone graft substitutes that can quickly, effectively, and safely repair large segmental bone defects. One emerging field of interest involves the growth of engineered bone tissue in vitro within bioreactors, the most promising of which are perfusion bioreactors. Using bioreactor systems, tissue engineered bone constructs can be fabricated in vitro. However, these engineered constructs lack inherent vasculature and once implanted, quickly develop a necrotic core, where no nutrient exchange occurs. Here, we utilized COMSOL modeling to predict oxygen diffusion gradients throughout aggregated alginate constructs, which allowed for the computer-aided design of printable vascular networks, compatible with any large tissue engineered construct cultured in a perfusion bioreactor. We investigated the effect of 3D printed macroscale vascular networks with various porosities on the viability of human mesenchymal stem cells in vitro, using both gas-permeable, and non-gas permeable bioreactor growth chamber walls. Through the use of 3D printed vascular structures in conjunction with a tubular perfusion system bioreactor, cell viability was found to increase by as much as 50% in the core of these constructs, with in silico modeling predicting construct viability at steady state. PMID:27272210

  11. Microvascular Guidance: A Challenge to Support the Development of Vascularised Tissue Engineering Construct

    PubMed Central

    Sukmana, Irza

    2012-01-01

    The guidance of endothelial cell organization into a capillary network has been a long-standing challenge in tissue engineering. Some research efforts have been made to develop methods to promote capillary networks inside engineered tissue constructs. Capillary and vascular networks that would mimic blood microvessel function can be used to subsequently facilitate oxygen and nutrient transfer as well as waste removal. Vascularization of engineering tissue construct is one of the most favorable strategies to overpass nutrient and oxygen supply limitation, which is often the major hurdle in developing thick and complex tissue and artificial organ. This paper addresses recent advances and future challenges in developing three-dimensional culture systems to promote tissue construct vascularization allowing mimicking blood microvessel development and function encountered in vivo. Bioreactors systems that have been used to create fully vascularized functional tissue constructs will also be outlined. PMID:22623881

  12. Space construction activities

    NASA Technical Reports Server (NTRS)

    1991-01-01

    The Center for Space Construction at the University of Colorado at Boulder was established in 1988 as a University Space Engineering Research Center. The mission of the Center is to conduct interdisciplinary engineering research which is critical to the construction of future space structures and systems and to educate students who will have the vision and technical skills to successfully lead future space construction activities. The research activities are currently organized around two central projects: Orbital Construction and Lunar Construction. Summaries of the research projects are included.

  13. Opportunities for Multidisciplinary Research in Partnership with Rock Engineers at the Deep Underground Science and Engineering Laboratory

    NASA Astrophysics Data System (ADS)

    Laughton, C.

    2008-12-01

    For the last half century the physics community has increasingly turned to the use of underground space to conduct basic research. The community is currently planning to conduct a new generation of underground experiments at the Deep Underground Science and Engineering Laboratory (DUSEL). DUSEL will be constructed within the footprint of the defunct Homestake Gold Mine, located in Lead, South Dakota. Physics proposals call for the construction of new caverns in which to conduct major new experiments. Some of the proposed laboratory facilities will be significantly larger and deeper than any previously constructed. The talk will highlight possible opportunities for integrating multi-disciplinary research in to the cavern construction program, and will stress the need to work closely with design and construction contractors to ensure that research goals can be achieve with minimal impact on project work. The constructors of large caverns should be particularly receptive to, and encouraging of geoscience research that could improve the engineering characterization of the rock mass. An improved understanding of the rock mass, as the host construction material, would result in a more reliable cavern design and construction process, and a reduced construction risk to the Project.

  14. The trajectories of Prevention through Design in construction.

    PubMed

    Toole, T Michael; Gambatese, John

    2008-01-01

    Construction Hazards Prevention through Design (CHPtD) is a process in which engineers and architects explicitly consider the safety of construction workers during the design process. Although articles on CHPtD have appeared in top construction journals, the literature has not addressed technical principles underlying CHPtD to help designers better perform CHPtD, to facilitate the development of additional CHPtD tools, and to predict the future path of CHPtD. This theoretical paper uses the existing literature on CHPtD and current action research associated with several CHPtD workgroups to analyze how CHPtD will likely evolve over the coming decades. There are four trajectories along which CHPtD will progress. (a) Designs will increasingly facilitate prefabricated construction; (b) designers will increasingly choose materials and systems that are inherently safer than alternatives; (c) designers will increasingly perform construction engineering; and (d) designers will increasingly apply spatial considerations to reduce worker hazards. By understanding how CHPtD may be manifested in the engineering-procurement-construction (EPC) industry, practitioners can better prepare for adopting CHPtD within their organizations and construction and engineering educators can better prepare their graduates to perform CHPtD.

  15. 7 CFR 1724.32 - Inspection and certification of work order construction.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ...) RURAL UTILITIES SERVICE, DEPARTMENT OF AGRICULTURE ELECTRIC ENGINEERING, ARCHITECTURAL SERVICES AND... construction. The provisions of this section apply to all borrower electric system facilities regardless of the... performed within 6 months of the completion of construction, and are performed by a licensed engineer...

  16. 7 CFR 1724.32 - Inspection and certification of work order construction.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ...) RURAL UTILITIES SERVICE, DEPARTMENT OF AGRICULTURE ELECTRIC ENGINEERING, ARCHITECTURAL SERVICES AND... construction. The provisions of this section apply to all borrower electric system facilities regardless of the... performed within 6 months of the completion of construction, and are performed by a licensed engineer...

  17. Automated construction of arterial and venous trees in retinal images

    PubMed Central

    Hu, Qiao; Abràmoff, Michael D.; Garvin, Mona K.

    2015-01-01

    Abstract. While many approaches exist to segment retinal vessels in fundus photographs, only a limited number focus on the construction and disambiguation of arterial and venous trees. Previous approaches are local and/or greedy in nature, making them susceptible to errors or limiting their applicability to large vessels. We propose a more global framework to generate arteriovenous trees in retinal images, given a vessel segmentation. In particular, our approach consists of three stages. The first stage is to generate an overconnected vessel network, named the vessel potential connectivity map (VPCM), consisting of vessel segments and the potential connectivity between them. The second stage is to disambiguate the VPCM into multiple anatomical trees, using a graph-based metaheuristic algorithm. The third stage is to classify these trees into arterial or venous (A/V) trees. We evaluated our approach with a ground truth built based on a public database, showing a pixel-wise classification accuracy of 88.15% using a manual vessel segmentation as input, and 86.11% using an automatic vessel segmentation as input. PMID:26636114

  18. Final Environmental Assessment: Addressing Construction of a New Civil Engineering Workshop at Bellows Air Force Station, O’ahu, Hawaii

    DTIC Science & Technology

    2010-03-01

    FINAL ENVIRONMENTAL ASSESSMENT ADDRESSING CONSTRUCTION OF A NEW CIVIL ENGINEERING WORKSHOP AT BELLOWS AIR FORCE STATION , O‘AHU, HAWAI‘I...Minimize impacts on other Bellows AFS functions and environmental resources This alternative would be located in an area located near Building 546 and...Preparation of An Environmental Assessment for the Proposed Construction of New Civil Engineering Workshop at Bellows Air !Force Station Thank you

  19. Review on antibacterial characteristics of bridge engineering biomaterials.

    PubMed

    Zhao, Qing-Qing; Chen, Meng-Yao; He, Rui-Lin; Zhang, Zhong-Feng; Ashraf, Muhammad Aqeel

    2016-01-01

    This review summarizes the research on timber construction materials used in bridge construction. It focuses on the application of antiseptic treatments and the use of timber engineering materials in decks and bridges. This review also provides an overview on the future research and prospects of engineered timber materials.

  20. 30 CFR 36.23 - Engine intake system.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 30 Mineral Resources 1 2013-07-01 2013-07-01 false Engine intake system. 36.23 Section 36.23... EQUIPMENT Construction and Design Requirements § 36.23 Engine intake system. (a) Construction. The intake... intake system without permanent deformation and shall prevent the propagation of flame through the joint...

  1. Space Transportation System Western Launch Site Construction Management Information System - A Case Study.

    DTIC Science & Technology

    1979-09-01

    The Corps of Engineers Management Information System (COEMIS) is used by the Corps of Engineers in their role as Construction Agents on Air Force...California. The research concluded that the Corps of Engineers Management Information System can be an effective, efficient management tool which has the

  2. Cytocompatibility and biologic characteristics of synthetic scaffold materials of rabbit acellular vascular matrix combining with human-like collagen I.

    PubMed

    Liu, Xuqian; Wang, Jie; Dong, Fusheng; Song, Peng; Tian, Songbo; Li, Hexiang; Hou, Yali

    2017-10-01

    Scaffold material provides a three-dimensional growing environment for seed cells in the research field of tissue engineering. In the present study, rabbit arterial blood vessel cells were chemically removed with trypsin and Triton X-100 to prepare rabbit acellular vascular matrix scaffold material. Observation by He&Masson staining revealed that no cellular components or nuclei existed in the vascular intima and media after decellularization. Human-like collagen I was combined with acellular vascular matrix by freeze-drying to prepare an acellular vascular matrix-0.25% human-like collagen I scaffold to compensate for the extracellular matrix loss during the decellularization process. We next performed a series of experiments to test the water absorbing quality, biomechanics, pressure resistance, cytotoxicity, and ultra-micro structure of the acellular vascular matrix composite material and natural rabbit artery and found that the acellular vascular matrix-0.25% human-like collagen I material behaved similarly to natural rabbit artery. In conclusion, the acellular vascular matrix-0.25% human-like collagen I composite material provides a new approach and lays the foundation for novel scaffold material research into tissue engineering of blood vessels.

  3. The Tissue-Engineered Vascular Graft—Past, Present, and Future

    PubMed Central

    Pashneh-Tala, Samand; MacNeil, Sheila

    2016-01-01

    Cardiovascular disease is the leading cause of death worldwide, with this trend predicted to continue for the foreseeable future. Common disorders are associated with the stenosis or occlusion of blood vessels. The preferred treatment for the long-term revascularization of occluded vessels is surgery utilizing vascular grafts, such as coronary artery bypass grafting and peripheral artery bypass grafting. Currently, autologous vessels such as the saphenous vein and internal thoracic artery represent the gold standard grafts for small-diameter vessels (<6 mm), outperforming synthetic alternatives. However, these vessels are of limited availability, require invasive harvest, and are often unsuitable for use. To address this, the development of a tissue-engineered vascular graft (TEVG) has been rigorously pursued. This article reviews the current state of the art of TEVGs. The various approaches being explored to generate TEVGs are described, including scaffold-based methods (using synthetic and natural polymers), the use of decellularized natural matrices, and tissue self-assembly processes, with the results of various in vivo studies, including clinical trials, highlighted. A discussion of the key areas for further investigation, including graft cell source, mechanical properties, hemodynamics, integration, and assessment in animal models, is then presented. PMID:26447530

  4. A mathematical model of atherogenesis as an inflammatory response.

    PubMed

    Ibragimov, A I; McNeal, C J; Ritter, L R; Walton, J R

    2005-12-01

    We construct a mathematical model of the early formation of an atherosclerotic lesion based on a simplification of Russell Ross' paradigm of atherosclerosis as a chronic inflammatory response. Atherosclerosis is a disease characterized by the accumulation of lipid-laden cells in the arterial wall. This disease results in lesions within the artery that may grow into the lumen restricting blood flow and, in critical cases, can rupture causing complete, sudden occlusion of the artery resulting in heart attack, stroke and possibly death. It is now understood that when chemically modified low-density lipoproteins (LDL cholesterol) enter into the wall of the human artery, they can trigger an immune response mediated by biochemical signals sent and received by immune and other cells indigenous to the vasculature. The presence of modified LDL can also corrupt the normal immune function triggering further immune response and ultimately chronic inflammation. In the construction of our mathematical model, we focus on the inflammatory component of the pathogenesis of cardiovascular disease (CVD). Because this study centres on the interplay between chemical and cellular species in the human artery and bloodstream, we employ a model of chemotaxis first given by E. F. Keller and Lee Segel in 1970 and present our model as a coupled system of non-linear reaction diffusion equations describing the state of the various species involved in the disease process. We perform numerical simulations demonstrating that our model captures certain observed features of CVD such as the localization of immune cells, the build-up of lipids and debris and the isolation of a lesion by smooth muscle cells.

  5. A New Method for Cerebral Arterial Stiffness by Measuring Pulse Wave Velocity Using Transcranial Doppler.

    PubMed

    Fu, Xian; Huang, Chuming; Wong, Ka Sing; Chen, Xiangyan; Gao, Qingchun

    2016-08-01

    Pulse wave velocity (PWV) has been regarded as the "gold standard" measurement of arterial stiffness (AS), but it is still only used in the assessment of central and peripheral arteries. We constructed a new method to evaluate cerebral AS by measuring PWV using transcranial Doppler (TCD). In all, 90 healthy subjects who received annual health screening were consecutively enrolled in this study between January 2011 and June 2013. Data on clinical characteristics, brachium-ankle (ba) PWV, and carotid-cerebral (cc) PWV measured with our newly constructed method by two experienced operators were recorded. cc PWV was calculated as the distance between two points in the common carotid artery and proximal part of ipsilateral middle cerebral artery, which was divided by the pulse transit time between these two points where the pulse was measured using TCD. The value of cc PWV was 499.3±78.6 cm/s. Correlation between cc PWV and ba PWV in the assessment of AS was r=0.794 (P＜0.001). The concordance between both the above mentioned methods was good. Interobserver and intraobserver reliability using interclass correlation for measuring cc PWV were 0.815 (P＜0.001) and 0.939 (P＜0.001), respectively. In multivariable analysis, older age (β=4.51, P＜0.001) and increased diastolic blood pressure (β=2.39, P＜0.001) were independently associated with higher cc PWV. cc PWV measured using TCD may be a promising method for the assessment of human cerebral AS, which is independently associated with age and diastolic blood pressure.

  6. A modular approach to creating large engineered cartilage surfaces.

    PubMed

    Ford, Audrey C; Chui, Wan Fung; Zeng, Anne Y; Nandy, Aditya; Liebenberg, Ellen; Carraro, Carlo; Kazakia, Galateia; Alliston, Tamara; O'Connell, Grace D

    2018-01-23

    Native articular cartilage has limited capacity to repair itself from focal defects or osteoarthritis. Tissue engineering has provided a promising biological treatment strategy that is currently being evaluated in clinical trials. However, current approaches in translating these techniques to developing large engineered tissues remains a significant challenge. In this study, we present a method for developing large-scale engineered cartilage surfaces through modular fabrication. Modular Engineered Tissue Surfaces (METS) uses the well-known, but largely under-utilized self-adhesion properties of de novo tissue to create large scaffolds with nutrient channels. Compressive mechanical properties were evaluated throughout METS specimens, and the tensile mechanical strength of the bonds between attached constructs was evaluated over time. Raman spectroscopy, biochemical assays, and histology were performed to investigate matrix distribution. Results showed that by Day 14, stable connections had formed between the constructs in the METS samples. By Day 21, bonds were robust enough to form a rigid sheet and continued to increase in size and strength over time. Compressive mechanical properties and glycosaminoglycan (GAG) content of METS and individual constructs increased significantly over time. The METS technique builds on established tissue engineering accomplishments of developing constructs with GAG composition and compressive properties approaching native cartilage. This study demonstrated that modular fabrication is a viable technique for creating large-scale engineered cartilage, which can be broadly applied to many tissue engineering applications and construct geometries. Copyright © 2017 Elsevier Ltd. All rights reserved.

  7. Building information modelling review with potential applications in tunnel engineering of China.

    PubMed

    Zhou, Weihong; Qin, Haiyang; Qiu, Junling; Fan, Haobo; Lai, Jinxing; Wang, Ke; Wang, Lixin

    2017-08-01

    Building information modelling (BIM) can be applied to tunnel engineering to address a number of problems, including complex structure, extensive design, long construction cycle and increased security risks. To promote the development of tunnel engineering in China, this paper combines actual cases, including the Xingu mountain tunnel and the Shigu Mountain tunnel, to systematically analyse BIM applications in tunnel engineering in China. The results indicate that BIM technology in tunnel engineering is currently mainly applied during the design stage rather than during construction and operation stages. The application of BIM technology in tunnel engineering covers many problems, such as a lack of standards, incompatibility of different software, disorganized management, complex combination with GIS (Geographic Information System), low utilization rate and poor awareness. In this study, through summary of related research results and engineering cases, suggestions are introduced and an outlook for the BIM application in tunnel engineering in China is presented, which provides guidance for design optimization, construction standards and later operation maintenance.

  8. Building information modelling review with potential applications in tunnel engineering of China

    PubMed Central

    Zhou, Weihong; Qin, Haiyang; Fan, Haobo; Lai, Jinxing; Wang, Ke; Wang, Lixin

    2017-01-01

    Building information modelling (BIM) can be applied to tunnel engineering to address a number of problems, including complex structure, extensive design, long construction cycle and increased security risks. To promote the development of tunnel engineering in China, this paper combines actual cases, including the Xingu mountain tunnel and the Shigu Mountain tunnel, to systematically analyse BIM applications in tunnel engineering in China. The results indicate that BIM technology in tunnel engineering is currently mainly applied during the design stage rather than during construction and operation stages. The application of BIM technology in tunnel engineering covers many problems, such as a lack of standards, incompatibility of different software, disorganized management, complex combination with GIS (Geographic Information System), low utilization rate and poor awareness. In this study, through summary of related research results and engineering cases, suggestions are introduced and an outlook for the BIM application in tunnel engineering in China is presented, which provides guidance for design optimization, construction standards and later operation maintenance. PMID:28878970

  9. Building information modelling review with potential applications in tunnel engineering of China

    NASA Astrophysics Data System (ADS)

    Zhou, Weihong; Qin, Haiyang; Qiu, Junling; Fan, Haobo; Lai, Jinxing; Wang, Ke; Wang, Lixin

    2017-08-01

    Building information modelling (BIM) can be applied to tunnel engineering to address a number of problems, including complex structure, extensive design, long construction cycle and increased security risks. To promote the development of tunnel engineering in China, this paper combines actual cases, including the Xingu mountain tunnel and the Shigu Mountain tunnel, to systematically analyse BIM applications in tunnel engineering in China. The results indicate that BIM technology in tunnel engineering is currently mainly applied during the design stage rather than during construction and operation stages. The application of BIM technology in tunnel engineering covers many problems, such as a lack of standards, incompatibility of different software, disorganized management, complex combination with GIS (Geographic Information System), low utilization rate and poor awareness. In this study, through summary of related research results and engineering cases, suggestions are introduced and an outlook for the BIM application in tunnel engineering in China is presented, which provides guidance for design optimization, construction standards and later operation maintenance.

  10. Constructs and methods for genome editing and genetic engineering of fungi and protists

    DOEpatents

    Hittinger, Christopher Todd; Alexander, William Gerald

    2018-01-30

    Provided herein are constructs for genome editing or genetic engineering in fungi or protists, methods of using the constructs and media for use in selecting cells. The construct include a polynucleotide encoding a thymidine kinase operably connected to a promoter, suitably a constitutive promoter; a polynucleotide encoding an endonuclease operably connected to an inducible promoter; and a recognition site for the endonuclease. The constructs may also include selectable markers for use in selecting recombinations.

  11. A computational framework to characterize and compare the geometry of coronary networks.

    PubMed

    Bulant, C A; Blanco, P J; Lima, T P; Assunção, A N; Liberato, G; Parga, J R; Ávila, L F R; Pereira, A C; Feijóo, R A; Lemos, P A

    2017-03-01

    This work presents a computational framework to perform a systematic and comprehensive assessment of the morphometry of coronary arteries from in vivo medical images. The methodology embraces image segmentation, arterial vessel representation, characterization and comparison, data storage, and finally analysis. Validation is performed using a sample of 48 patients. Data mining of morphometric information of several coronary arteries is presented. Results agree to medical reports in terms of basic geometric and anatomical variables. Concerning geometric descriptors, inter-artery and intra-artery correlations are studied. Data reported here can be useful for the construction and setup of blood flow models of the coronary circulation. Finally, as an application example, similarity criterion to assess vasculature likelihood based on geometric features is presented and used to test geometric similarity among sibling patients. Results indicate that likelihood, measured through geometric descriptors, is stronger between siblings compared with non-relative patients. Copyright © 2016 John Wiley & Sons, Ltd. Copyright © 2016 John Wiley & Sons, Ltd.

  12. Constructing an Efficient Self-Tuning Aircraft Engine Model for Control and Health Management Applications

    NASA Technical Reports Server (NTRS)

    Armstrong, Jeffrey B.; Simon, Donald L.

    2012-01-01

    Self-tuning aircraft engine models can be applied for control and health management applications. The self-tuning feature of these models minimizes the mismatch between any given engine and the underlying engineering model describing an engine family. This paper provides details of the construction of a self-tuning engine model centered on a piecewise linear Kalman filter design. Starting from a nonlinear transient aerothermal model, a piecewise linear representation is first extracted. The linearization procedure creates a database of trim vectors and state-space matrices that are subsequently scheduled for interpolation based on engine operating point. A series of steady-state Kalman gains can next be constructed from a reduced-order form of the piecewise linear model. Reduction of the piecewise linear model to an observable dimension with respect to available sensed engine measurements can be achieved using either a subset or an optimal linear combination of "health" parameters, which describe engine performance. The resulting piecewise linear Kalman filter is then implemented for faster-than-real-time processing of sensed engine measurements, generating outputs appropriate for trending engine performance, estimating both measured and unmeasured parameters for control purposes, and performing on-board gas-path fault diagnostics. Computational efficiency is achieved by designing multidimensional interpolation algorithms that exploit the shared scheduling of multiple trim vectors and system matrices. An example application illustrates the accuracy of a self-tuning piecewise linear Kalman filter model when applied to a nonlinear turbofan engine simulation. Additional discussions focus on the issue of transient response accuracy and the advantages of a piecewise linear Kalman filter in the context of validation and verification. The techniques described provide a framework for constructing efficient self-tuning aircraft engine models from complex nonlinear simulations.Self-tuning aircraft engine models can be applied for control and health management applications. The self-tuning feature of these models minimizes the mismatch between any given engine and the underlying engineering model describing an engine family. This paper provides details of the construction of a self-tuning engine model centered on a piecewise linear Kalman filter design. Starting from a nonlinear transient aerothermal model, a piecewise linear representation is first extracted. The linearization procedure creates a database of trim vectors and state-space matrices that are subsequently scheduled for interpolation based on engine operating point. A series of steady-state Kalman gains can next be constructed from a reduced-order form of the piecewise linear model. Reduction of the piecewise linear model to an observable dimension with respect to available sensed engine measurements can be achieved using either a subset or an optimal linear combination of "health" parameters, which describe engine performance. The resulting piecewise linear Kalman filter is then implemented for faster-than-real-time processing of sensed engine measurements, generating outputs appropriate for trending engine performance, estimating both measured and unmeasured parameters for control purposes, and performing on-board gas-path fault diagnostics. Computational efficiency is achieved by designing multidimensional interpolation algorithms that exploit the shared scheduling of multiple trim vectors and system matrices. An example application illustrates the accuracy of a self-tuning piecewise linear Kalman filter model when applied to a nonlinear turbofan engine simulation. Additional discussions focus on the issue of transient response accuracy and the advantages of a piecewise linear Kalman filter in the context of validation and verification. The techniques described provide a framework for constructing efficient self-tuning aircraft engine models from complex nonlinear simulatns.

  13. Arterial tree tracking from anatomical landmarks in magnetic resonance angiography scans

    NASA Astrophysics Data System (ADS)

    O'Neil, Alison; Beveridge, Erin; Houston, Graeme; McCormick, Lynne; Poole, Ian

    2014-03-01

    This paper reports on arterial tree tracking in fourteen Contrast Enhanced MRA volumetric scans, given the positions of a predefined set of vascular landmarks, by using the A* algorithm to find the optimal path for each vessel based on voxel intensity and a learnt vascular probability atlas. The algorithm is intended for use in conjunction with an automatic landmark detection step, to enable fully automatic arterial tree tracking. The scan is filtered to give two further images using the top-hat transform with 4mm and 8mm cubic structuring elements. Vessels are then tracked independently on the scan in which the vessel of interest is best enhanced, as determined from knowledge of typical vessel diameter and surrounding structures. A vascular probability atlas modelling expected vessel location and orientation is constructed by non-rigidly registering the training scans to the test scan using a 3D thin plate spline to match landmark correspondences, and employing kernel density estimation with the ground truth center line points to form a probability density distribution. Threshold estimation by histogram analysis is used to segment background from vessel intensities. The A* algorithm is run using a linear cost function constructed from the threshold and the vascular atlas prior. Tracking results are presented for all major arteries excluding those in the upper limbs. An improvement was observed when tracking was informed by contextual information, with particular benefit for peripheral vessels.

  14. Tissue-engineered cartilaginous constructs for the treatment of caprine cartilage defects, including distribution of laminin and type IV collagen.

    PubMed

    Jeng, Lily; Hsu, Hu-Ping; Spector, Myron

    2013-10-01

    The purpose of this study was the immunohistochemical evaluation of (1) cartilage tissue-engineered constructs; and (2) the tissue filling cartilage defects in a goat model into which the constructs were implanted, particularly for the presence of the basement membrane molecules, laminin and type IV collagen. Basement membrane molecules are localized to the pericellular matrix in normal adult articular cartilage, but have not been examined in tissue-engineered constructs cultured in vitro or in tissue filling cartilage defects into which the constructs were implanted. Cartilaginous constructs were engineered in vitro using caprine chondrocyte-seeded type II collagen scaffolds. Autologous constructs were implanted into 4-mm-diameter defects created to the tidemark in the trochlear groove in the knee joints of skeletally mature goats. Eight weeks after implantation, the animals were sacrificed. Constructs underwent immunohistochemical and histomorphometric evaluation. Widespread staining for the two basement membrane molecules was observed throughout the extracellular matrix of in vitro and in vivo samples in a distribution unlike that previously reported for cartilage. At sacrifice, 70% of the defect site was filled with reparative tissue, which consisted largely of fibrous tissue and some fibrocartilage, with over 70% of the reparative tissue bonded to the adjacent host tissue. A novel finding of this study was the observation of laminin and type IV collagen in in vitro engineered cartilaginous constructs and in vivo cartilage repair samples from defects into which the constructs were implanted, as well as in normal caprine articular cartilage. Future work is needed to elucidate the role of basement membrane molecules during cartilage repair and regeneration.

  15. Tissue-Engineered Cartilaginous Constructs for the Treatment of Caprine Cartilage Defects, Including Distribution of Laminin and Type IV Collagen

    PubMed Central

    Jeng, Lily; Hsu, Hu-Ping

    2013-01-01

    The purpose of this study was the immunohistochemical evaluation of (1) cartilage tissue-engineered constructs; and (2) the tissue filling cartilage defects in a goat model into which the constructs were implanted, particularly for the presence of the basement membrane molecules, laminin and type IV collagen. Basement membrane molecules are localized to the pericellular matrix in normal adult articular cartilage, but have not been examined in tissue-engineered constructs cultured in vitro or in tissue filling cartilage defects into which the constructs were implanted. Cartilaginous constructs were engineered in vitro using caprine chondrocyte-seeded type II collagen scaffolds. Autologous constructs were implanted into 4-mm-diameter defects created to the tidemark in the trochlear groove in the knee joints of skeletally mature goats. Eight weeks after implantation, the animals were sacrificed. Constructs underwent immunohistochemical and histomorphometric evaluation. Widespread staining for the two basement membrane molecules was observed throughout the extracellular matrix of in vitro and in vivo samples in a distribution unlike that previously reported for cartilage. At sacrifice, 70% of the defect site was filled with reparative tissue, which consisted largely of fibrous tissue and some fibrocartilage, with over 70% of the reparative tissue bonded to the adjacent host tissue. A novel finding of this study was the observation of laminin and type IV collagen in in vitro engineered cartilaginous constructs and in vivo cartilage repair samples from defects into which the constructs were implanted, as well as in normal caprine articular cartilage. Future work is needed to elucidate the role of basement membrane molecules during cartilage repair and regeneration. PMID:23672504

  16. Biomimicry, vascular restenosis and coronary stents.

    PubMed

    Schwartz, R S; van der Giessen, W J; Holmes, D R

    1998-01-01

    Biomimicry is in its earliest stages and is being considered in the realm of tissue engineering. If arterial implants are to limit neointimal thickening, purely passive structures cannot succeed. Bioactivity must be present, either by pharmacologic intervention or by fabricating a 'living stent' that contains active cellular material. As tissue engineering evolves, useful solutions will emerge from applying this knowledge directly to vascular biologic problems resulting from angioplasty, stenting, and vascular prosthesis research.

  17. 14 CFR 33.17 - Fire protection.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... STANDARDS: AIRCRAFT ENGINES Design and Construction; General § 33.17 Fire protection. (a) The design and... addition, the design and construction of turbine engines must minimize the probability of the occurrence of...

  18. 14 CFR 33.35 - Fuel and induction system.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... 14 Aeronautics and Space 1 2013-01-01 2013-01-01 false Fuel and induction system. 33.35 Section 33... AIRWORTHINESS STANDARDS: AIRCRAFT ENGINES Design and Construction; Reciprocating Aircraft Engines § 33.35 Fuel and induction system. (a) The fuel system of the engine must be designed and constructed to supply an...

  19. 14 CFR 33.35 - Fuel and induction system.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... 14 Aeronautics and Space 1 2014-01-01 2014-01-01 false Fuel and induction system. 33.35 Section 33... AIRWORTHINESS STANDARDS: AIRCRAFT ENGINES Design and Construction; Reciprocating Aircraft Engines § 33.35 Fuel and induction system. (a) The fuel system of the engine must be designed and constructed to supply an...

  20. 14 CFR 33.35 - Fuel and induction system.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... 14 Aeronautics and Space 1 2011-01-01 2011-01-01 false Fuel and induction system. 33.35 Section 33... AIRWORTHINESS STANDARDS: AIRCRAFT ENGINES Design and Construction; Reciprocating Aircraft Engines § 33.35 Fuel and induction system. (a) The fuel system of the engine must be designed and constructed to supply an...

  1. 14 CFR 33.35 - Fuel and induction system.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... 14 Aeronautics and Space 1 2012-01-01 2012-01-01 false Fuel and induction system. 33.35 Section 33... AIRWORTHINESS STANDARDS: AIRCRAFT ENGINES Design and Construction; Reciprocating Aircraft Engines § 33.35 Fuel and induction system. (a) The fuel system of the engine must be designed and constructed to supply an...

  2. 14 CFR 33.39 - Lubrication system.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... 14 Aeronautics and Space 1 2014-01-01 2014-01-01 false Lubrication system. 33.39 Section 33.39... system. (a) The lubrication system of the engine must be designed and constructed so that it will... supply is in the engine. (b) The lubrication system of the engine must be designed and constructed to...

  3. Design Guide for Selection and Specification of Kevlar Rope for Ocean Engineering and Construction.

    DTIC Science & Technology

    1976-07-01

    public rtoieco cnd sol . It i Idim .buttm Is ul"rnimi.. OCEAN ENGINEERING AND CONSTRUCTION PROJECT OFFICE CHESAPEAKE DIVISION NAVAL FACILITIES ENGINEERING...be to have no more than one layer. This is impractical for oceano - graphic purposes. Assuming a need to spooi many layers of rope under tension

  4. In vitro evaluation of physiological spiral anastomoses for the arterial switch operation in simple transposition of the great arteries: a first step towards a surgical alternative?

    PubMed

    Sievers, Hans-Hinrich; Scharfschwerdt, Michael; Putman, Léon M

    2015-08-01

    The currently most frequently used technique for the arterial switch operation (ASO) in simple transposition of the great arteries (TGA) includes the transposition of the pulmonary artery anterior to the ascending aorta. This arterial arrangement is less anatomical, and although the initial results are excellent, some long-term data are indicating a certain risk of morbidity, encouraging the search for more physiological techniques. As a first step, we studied the feasibility of anatomical spiral anastomoses of the great vessels in vitro. A TGA model was constructed to simulate the different spatial positions of the great arteries followed by ASO with physiological spiral connections of the great arteries. It was possible to perform a physiological spiral connection of the great arteries without tension or torsion when the roots of the great vessels were arranged anterior-posterior and with up to 35° rotation of the aortic root to the right around the pulmonary root. With further rotation of the aorta, patch plasties were required for pulmonary artery elongation. The maximal width of the patch was 5 mm. In this TGA model, it was possible to perform tension- and torsion-free arterial anastomoses for ASO without artificial material, when the aortic root was positioned from 0° up to 35° to the right of the pulmonary root. Evaluation of coronary transfer is the next step. © The Author 2015. Published by Oxford University Press on behalf of the European Association for Cardio-Thoracic Surgery. All rights reserved.

  5. CFD simulation of blood flow inside the corkscrew collaterals of the Buerger's disease.

    PubMed

    Sharifi, Alireza; Charjouei Moghadam, Mohammad

    2016-01-01

    Buerger's disease is an occlusive arterial disease that occurs mainly in medium and small vessels. This disease is associated with Tobacco usage. The existence of corkscrew collateral is one of the established characteristics of the Buerger's disease. In this study, the computational fluid dynamics (CFD) simulation of blood flow within the corkscrew artery of the Buerger's disease is conducted. The geometry of the artery is constructed based on the actual corkscrew artery of a patient diagnosed with the Buerger's disease. The blood properties are the same as the actual blood properties of the patient. The blood flow rate is taken from the available experimental data in the literature. The local velocity patterns, pressure and kinematic viscosity distributions in different segments of the corkscrew collateral artery was demonstrated and discussed for the first time for this kind of artery. The effects of non-Newtonian consideration for the blood viscosity behavior were investigated in different segments of the artery. Moreover, the variations of the blood flow patterns along the artery were investigated in details for each segment. It was found that the flow patterns were affected by the complex geometry of this artery in such a way that it could lead to the presence of sites that were prone to the accumulation of the flowing particles in blood like nicotine. Furthermore, due to the existence of many successive bends in this artery, the variations of kinematic viscosity along this artery were significant, therefore the non-Newtonian behavior of the blood viscosity must be considered.

  6. CFD simulation of blood flow inside the corkscrew collaterals of the Buerger’s disease

    PubMed Central

    Sharifi, Alireza; Charjouei Moghadam, Mohammad

    2016-01-01

    Introduction: Buerger’s disease is an occlusive arterial disease that occurs mainly in medium and small vessels. This disease is associated with Tobacco usage. The existence of corkscrew collateral is one of the established characteristics of the Buerger’s disease. Methods: In this study, the computational fluid dynamics (CFD) simulation of blood flow within the corkscrew artery of the Buerger’s disease is conducted. The geometry of the artery is constructed based on the actual corkscrew artery of a patient diagnosed with the Buerger’s disease. The blood properties are the same as the actual blood properties of the patient. The blood flow rate is taken from the available experimental data in the literature. Results: The local velocity patterns, pressure and kinematic viscosity distributions in different segments of the corkscrew collateral artery was demonstrated and discussed for the first time for this kind of artery. The effects of non-Newtonian consideration for the blood viscosity behavior were investigated in different segments of the artery. Moreover, the variations of the blood flow patterns along the artery were investigated in details for each segment. Conclusion: It was found that the flow patterns were affected by the complex geometry of this artery in such a way that it could lead to the presence of sites that were prone to the accumulation of the flowing particles in blood like nicotine. Furthermore, due to the existence of many successive bends in this artery, the variations of kinematic viscosity along this artery were significant, therefore the non-Newtonian behavior of the blood viscosity must be considered. PMID:27340623

  7. Tendon and ligament as novel cell sources for engineering the knee meniscus.

    PubMed

    Hadidi, P; Paschos, N K; Huang, B J; Aryaei, A; Hu, J C; Athanasiou, K A

    2016-12-01

    The application of cell-based therapies in regenerative medicine is hindered by the difficulty of acquiring adequate numbers of competent cells. For the knee meniscus in particular, this may be solved by harvesting tissue from neighboring tendons and ligaments. In this study, we have investigated the potential of cells from tendon and ligament, as compared to meniscus cells, to engineer scaffold-free self-assembling fibrocartilage. Self-assembling meniscus-shaped constructs engineered from a co-culture of articular chondrocytes and either meniscus, tendon, or ligament cells were cultured for 4 weeks with TGF-β1 in serum-free media. After culture, constructs were assessed for their mechanical properties, histological staining, gross appearance, and biochemical composition including cross-link content. Correlations were performed to evaluate relationships between biochemical content and mechanical properties. In terms of mechanical properties as well as biochemical content, constructs engineered using tenocytes and ligament fibrocytes were found to be equivalent or superior to constructs engineered using meniscus cells. Furthermore, cross-link content was found to be correlated with engineered tissue tensile properties. Tenocytes and ligament fibrocytes represent viable cell sources for engineering meniscus fibrocartilage using the self-assembling process. Due to greater cross-link content, fibrocartilage engineered with tenocytes and ligament fibrocytes may maintain greater tensile properties than fibrocartilage engineered with meniscus cells. Copyright © 2016 Osteoarthritis Research Society International. Published by Elsevier Ltd. All rights reserved.

  8. Tendon and ligament as novel cell sources for engineering the knee meniscus

    PubMed Central

    Hadidi, Pasha; Paschos, Nikolaos K.; Huang, Brian J.; Aryaei, Ashkan; Hu, Jerry C.; Athanasiou, Kyriacos A.

    2016-01-01

    Objective The application of cell-based therapies in regenerative medicine is hindered by the difficulty of acquiring adequate numbers of competent cells. For the knee meniscus in particular, this may be solved by harvesting tissue from neighboring tendons and ligaments. In this study, we have investigated the potential of cells from tendon and ligament, as compared to meniscus cells, to engineer scaffold-free self-assembling fibrocartilage. Method Self-assembling meniscus-shaped constructs engineered from a co-culture of articular chondrocytes and either meniscus, tendon, or ligament cells were cultured for 4 weeks with TGF-β1 in serum-free media. After culture, constructs were assessed for their mechanical properties, histological staining, gross appearance, and biochemical composition including cross-link content. Correlations were performed to evaluate relationships between biochemical content and mechanical properties. Results In terms of mechanical properties as well as biochemical content, constructs engineered using tenocytes and ligament fibrocytes were found to be equivalent or superior to constructs engineered using meniscus cells. Furthermore, cross-link content was found to be correlated with engineered tissue tensile properties. Conclusion Tenocytes and ligament fibrocytes represent viable cell sources for engineering meniscus fibrocartilage using the self-assembling process. Due to greater cross-link content, fibrocartilage engineered with tenocytes and ligament fibrocytes may maintain greater tensile properties than fibrocartilage engineered with meniscus cells. PMID:27473559

  9. The Local Construction of the Asymmetrical Power Relationship in Teamwork among Engineers

    ERIC Educational Resources Information Center

    Vickers, Caroline H.

    2010-01-01

    The purpose of this article is to examine local, interactional processes associated with the construction of power asymmetries in collaborative teamwork among engineering students. To explore the construction of power asymmetries at the micro-interactional level, this article examines a corpus consisting of about 150,000 words in which seven teams…

  10. Construction Site Environmental Impact in Civil Engineering Education

    ERIC Educational Resources Information Center

    Teixeira, Jose M. Cardoso

    2005-01-01

    The environmental impact of construction activity has gained increasing importance in the last few years and become a key subject for civil engineering education. A survey of Portuguese higher education institutions shows that concern with this topic is mostly directed at the impact of large construction projects and especially focused on their…

  11. 78 FR 23837 - Cranes and Derricks in Construction: Underground Construction and Demolition

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-04-23

    ... report here the results for the entire heavy-and-civil engineering sector and the entire site... in this final rule because employers included in the heavy-and-civil engineering sector, or the site... final rule. This final rule affects two construction sectors: NAICS 237990 (Other Heavy and Civil...

  12. Study on energy consumption evaluation of mountainous highway based on LCA

    NASA Astrophysics Data System (ADS)

    Fei, Lunlin; Zhang, Qi; Xie, Yongqing

    2017-06-01

    For the system to understand the road construction energy consumption process, this paper selects a typical mountainous highway in the south, using the theory and method of Life Cycle Assessment (LCA) to quantitatively study the energy consumption of the whole process of highway raw materials production, construction and operation. The results show that the energy consumption in the raw material production stage is the highest, followed by the highway operation and construction stage. The energy consumption per unit of tunnel engineering, bridge engineering, roadbed engineering and pavement engineering in the construction phase are 2279.00 tce, 1718.07 tce, 542.19 tce and 34.02 tce, and in operational phase, 85.44% of electricity consumption comes from tunnel ventilation and lighting. Therefore, in the bridge and tunnel construction process, we should promote energy-saving innovation of the construction technology and mechanical equipment, and further strengthen the research and development of tunnel ventilation, lighting energy-saving equipment and intelligent control technology, which will help significantly reduce the energy consumption and greenhouse gas emissions of the life cycle of highway.

  13. Enhancing Knowledge Sharing Management Using BIM Technology in Construction

    PubMed Central

    Ho, Shih-Ping; Tserng, Hui-Ping

    2013-01-01

    Construction knowledge can be communicated and reused among project managers and jobsite engineers to alleviate problems on a construction jobsite and reduce the time and cost of solving problems related to constructability. This paper proposes a new methodology for the sharing of construction knowledge by using Building Information Modeling (BIM) technology. The main characteristics of BIM include illustrating 3D CAD-based presentations and keeping information in a digital format and facilitation of easy updating and transfer of information in the BIM environment. Using the BIM technology, project managers and engineers can gain knowledge related to BIM and obtain feedback provided by jobsite engineers for future reference. This study addresses the application of knowledge sharing management using BIM technology and proposes a BIM-based Knowledge Sharing Management (BIMKSM) system for project managers and engineers. The BIMKSM system is then applied in a selected case study of a construction project in Taiwan to demonstrate the effectiveness of sharing knowledge in the BIM environment. The results demonstrate that the BIMKSM system can be used as a visual BIM-based knowledge sharing management platform by utilizing the BIM technology. PMID:24723790

  14. Enhancing knowledge sharing management using BIM technology in construction.

    PubMed

    Ho, Shih-Ping; Tserng, Hui-Ping; Jan, Shu-Hui

    2013-01-01

    Construction knowledge can be communicated and reused among project managers and jobsite engineers to alleviate problems on a construction jobsite and reduce the time and cost of solving problems related to constructability. This paper proposes a new methodology for the sharing of construction knowledge by using Building Information Modeling (BIM) technology. The main characteristics of BIM include illustrating 3D CAD-based presentations and keeping information in a digital format and facilitation of easy updating and transfer of information in the BIM environment. Using the BIM technology, project managers and engineers can gain knowledge related to BIM and obtain feedback provided by jobsite engineers for future reference. This study addresses the application of knowledge sharing management using BIM technology and proposes a BIM-based Knowledge Sharing Management (BIMKSM) system for project managers and engineers. The BIMKSM system is then applied in a selected case study of a construction project in Taiwan to demonstrate the effectiveness of sharing knowledge in the BIM environment. The results demonstrate that the BIMKSM system can be used as a visual BIM-based knowledge sharing management platform by utilizing the BIM technology.

  15. Intra-arterial pressure measurement in neonates: dynamic response requirements.

    PubMed

    van Genderingen, H R; Gevers, M; Hack, W W

    1995-02-01

    A computer simulation of a catheter manometer system was used to quantify measurement errors in neonatal blood pressure parameters. Accurate intra-arterial pressure recordings of 21 critically ill newborns were fed into this simulated system. The dynamic characteristics, natural frequency and damping coefficient, were varied from 2.5 to 60 Hz and from 0.1 to 1.4, respectively. As a result, errors in systolic, diastolic and pulse arterial pressure were obtained as a function of natural frequency and damping coefficient. Iso-error curves for 2%, 5% and 10% were constructed. Using these curves, the maximum inaccuracy of any neonatal catheter manometer system can be determined and used in the clinical setting.

  16. Inspection of Construction Works According to Polish Construction Law

    NASA Astrophysics Data System (ADS)

    Czemplik, A.

    2015-11-01

    Construction regulations are still different in many European countries, even though the European Union directives have unified many acts for construction works and construction products in the member countries. The scheme of the construction process presented in the paper could be valid for most countries, despite of detailed regulations of legal systems. The number of construction regulations to be followed in order to get the Construction Permit in Poland is rather big, so the time between the start of the investment process and the day when the Construction Permit is issued could be several months. Only licensed professional engineers can play the role of site managers, site inspectors and designers, registered for the given construction project. Duties and responsibilities (civil liability) of these engineers are strictly defined by regulations. The obligatory inspection of construction works should be executed by the licensed site inspectors. Moreover, the works can be incidentally inspected by Authority, banks, insurance companies or designers. Foreign designers and foreign site engineers in order to be allowed by respective Authority to play official roles on Polish construction sites should present documents proving that they can do the same jobs in their countries as per regulations obligatory there.

  17. An Analysis of Cost Premiums and Losses Associated with USAF Military Construction (MILCON)

    DTIC Science & Technology

    2013-03-01

    Corps of Engineers (USACE) or the Naval Facilities Engineering Command (NAVFAC) for design and construction of the annual military construction...AFCEC in lieu of AFCEE or AFCESA. The selection, and policies, of design and construction agents may cause cost premiums for Air Force MILCON...private industry best practices such as relational contracting, schedule performance, and design -build procurement methods. All of these research

  18. Evaluation of Glass Fiber Reinforced Concrete Panels for Use in Military Construction.

    DTIC Science & Technology

    1984-06-01

    AD-A158 134 UNCLASSIFIED EVALUATION OF GLASS FIBER REINFORCED CONCRETE PANELS FOR USE IN MILITARY. . (U) CONSTRUCTION ENGINEERING RESEARCH LAB...Construction Engineering Research Laboratory i=h-C=iU. TECHNICAL REPORT M-85/15 June 1985 AD-A158 134 0~- 8 Evaluation of Glass Fiber ...Reinforced Concrete Panels for Use in Military Construction by Gilbert R. Williamson Glass fiber reinforced concrete (GFRC) materials are investigated

  19. Wood products used in constructing conservation and development projects by the Corps of Engineers in the United States, 1962 and 1978

    Treesearch

    W. H. Reid; D. B. McKeever

    Estimates of the amounts of wood products used in constructing civil conservation and development projects by the Corps of Engineers in the United States are presented for the years 1962 and 1978. Amounts of lumber, laminated lumber, poles and piling, and plywood used in construction are stratified by five construction categories, and three types of uses. Estimates of...

  20. [Development of computer aided forming techniques in manufacturing scaffolds for bone tissue engineering].

    PubMed

    Wei, Xuelei; Dong, Fuhui

    2011-12-01

    To review recent advance in the research and application of computer aided forming techniques for constructing bone tissue engineering scaffolds. The literature concerning computer aided forming techniques for constructing bone tissue engineering scaffolds in recent years was reviewed extensively and summarized. Several studies over last decade have focused on computer aided forming techniques for bone scaffold construction using various scaffold materials, which is based on computer aided design (CAD) and bone scaffold rapid prototyping (RP). CAD include medical CAD, STL, and reverse design. Reverse design can fully simulate normal bone tissue and could be very useful for the CAD. RP techniques include fused deposition modeling, three dimensional printing, selected laser sintering, three dimensional bioplotting, and low-temperature deposition manufacturing. These techniques provide a new way to construct bone tissue engineering scaffolds with complex internal structures. With rapid development of molding and forming techniques, computer aided forming techniques are expected to provide ideal bone tissue engineering scaffolds.

  1. 3D bioprinting for vascularized tissue fabrication

    PubMed Central

    Richards, Dylan; Jia, Jia; Yost, Michael; Markwald, Roger; Mei, Ying

    2016-01-01

    3D bioprinting holds remarkable promise for rapid fabrication of 3D tissue engineering constructs. Given its scalability, reproducibility, and precise multi-dimensional control that traditional fabrication methods do not provide, 3D bioprinting provides a powerful means to address one of the major challenges in tissue engineering: vascularization. Moderate success of current tissue engineering strategies have been attributed to the current inability to fabricate thick tissue engineering constructs that contain endogenous, engineered vasculature or nutrient channels that can integrate with the host tissue. Successful fabrication of a vascularized tissue construct requires synergy between high throughput, high-resolution bioprinting of larger perfusable channels and instructive bioink that promotes angiogenic sprouting and neovascularization. This review aims to cover the recent progress in the field of 3D bioprinting of vascularized tissues. It will cover the methods of bioprinting vascularized constructs, bioink for vascularization, and perspectives on recent innovations in 3D printing and biomaterials for the next generation of 3D bioprinting for vascularized tissue fabrication. PMID:27230253

  2. Closed-loop recycling of construction and demolition waste in Germany in view of stricter environmental threshold values.

    PubMed

    Weil, Marcel; Jeske, Udo; Schebek, Liselotte

    2006-06-01

    Recycling of construction and demolition waste contributes decisively to the saving of natural mineral resources. In Germany, processed mineral construction and demolition waste from structural engineering is used nearly exclusively in civil engineering (earthwork and road construction sector) as open-loop recycling. Due to the planned stricter limit values for the protection of soil and water, however, this recycling path in civil engineering may no longer be applicable in the future. According to some new guidelines and standards adopted recently, recycled aggregates may also be used for concrete production in the structural engineering sector (closed-loop recycling). Wastes from the structural engineering sector can thus be kept in a closed cycle, and their disposal on a landfill can be avoided. The present report focuses on the determination of maximum waste volumes that may be handled by this new recycling option. Potential adverse effects on the saving of resources and climate protection have been analysed. For this purpose, materials flow analysis and ecobalancing methods have been used.

  3. Technician Career Opportunities in Engineering Technology.

    ERIC Educational Resources Information Center

    Engineers' Council for Professional Development, New York, NY.

    Career opportunities for engineering technicians are available in the technologies relating to air conditioning, heating, and refrigeration, aviation and aerospace, building construction, chemical engineering, civil engineering, electrical engineering, electronics, industrial engineering, instrumentation, internal combustion engines, mechanical…

  4. Differential osteogenic activity of osteoprogenitor cells on HA and TCP/HA scaffold of tissue engineered bone.

    PubMed

    Ng, Angela M H; Tan, K K; Phang, M Y; Aziyati, O; Tan, G H; Isa, M R; Aminuddin, B S; Naseem, M; Fauziah, O; Ruszymah, B H I

    2008-05-01

    Biomaterial, an essential component of tissue engineering, serves as a scaffold for cell attachment, proliferation, and differentiation; provides the three dimensional (3D) structure and, in some applications, the mechanical strength required for the engineered tissue. Both synthetic and naturally occurring calcium phosphate based biomaterial have been used as bone fillers or bone extenders in orthopedic and reconstructive surgeries. This study aims to evaluate two popular calcium phosphate based biomaterial i.e., hydroxyapatite (HA) and tricalcium phosphate/hydroxyapatite (TCP/HA) granules as scaffold materials in bone tissue engineering. In our strategy for constructing tissue engineered bone, human osteoprogenitor cells derived from periosteum were incorporated with human plasma-derived fibrin and seeded onto HA or TCP/HA forming 3D tissue constructs and further maintained in osteogenic medium for 4 weeks to induce osteogenic differentiation. Constructs were subsequently implanted intramuscularly in nude mice for 8 weeks after which mice were euthanized and constructs harvested for evaluation. The differential cell response to the biomaterial (HA or TCP/HA) adopted as scaffold was illustrated by the histology of undecalcified constructs and evaluation using SEM and TEM. Both HA and TCP/HA constructs showed evidence of cell proliferation, calcium deposition, and collagen bundle formation albeit lesser in the former. Our findings demonstrated that TCP/HA is superior between the two in early bone formation and hence is the scaffold material of choice in bone tissue engineering. Copyright 2007 Wiley Periodicals, Inc.

  5. In vitro engineering of fibrocartilage using CDMP1 induced dermal fibroblasts and polyglycolide.

    PubMed

    Zhao, Guiqing; Yin, Shuo; Liu, Guangpeng; Cen, Lian; Sun, Jian; Zhou, Heng; Liu, Wei; Cui, Lei; Cao, Yilin

    2009-07-01

    This study was designed to explore the feasibility of using cartilage-derived morphogenetic protein-1 (CDMP1) induced dermal fibroblasts (DFs) as seed cells and polyglycolide (PGA) as scaffold for fibrocartilage engineering. DFs isolated from canine were expanded and seeded on PGA scaffold to fabricate cell/scaffold constructs which were cultured with or without CDMP1. Proliferation and differentiation of DFs in different constructs were determined by DNA assay and glycosaminoglycan (GAG) production. Histological and immunohistochemical staining of the constructs after being in vitro cultured for 4 and 6 weeks were carried out to observe the fibrocartilage formation condition. The fibrocartilage-specific gene expression by cells in the constructs was analyzed by real-time PCR. It was shown that in the presence of CDMP1 the proliferation and GAG synthesis of DFs were significantly enhanced compared to those without CDMP1. Fibrocartilage-like tissue was formed in the CDMP1 induced construct after being cultured for 4 weeks, and it became more matured at 6 weeks as stronger staining for GAG and higher gene expression of collagen type II was observed. Since only weak staining for GAG and collagen type II was observed for the construct engineered without CDMP1, the induction effect on the fibrocartilage engineering can be ascertained when using DFs as seed cells. Furthermore, the potential of using DFs as seed cells to engineer fibrocartilage is substantiated and further study on using the engineered tissue to repair fibrocartilage defects is currently ongoing in our group.

  6. Comprehensive Engineering Approach to Achieving Safe Neighborhoods.

    DOT National Transportation Integrated Search

    2000-09-01

    Steady increases in travel demand coupled with minimal increases in arterial street capacity have led to an increase in traffic-related safety problems in residential neighborhoods. These problems stem from the significant number of motorists that di...

  7. What Have we Learned about Intelligent Transportation Systems?

    DOT National Transportation Integrated Search

    1980-01-01

    The Traffic Planning manual is a reference of basic traffic enginnering techniques and their potential for improving traffic flow and traffic safety of urban arterial streets and highways. The manual identifies the traffic engineering measure appropr...

  8. Comparison of methods for measuring travel time at Florida freeways and arterials : [summary].

    DOT National Transportation Integrated Search

    2014-07-01

    In this project, University of Florida researchers : collected field data along several highways to : evaluate travel time measurements from several : sources: STEWARD, BlueTOAD, INRIX, and HERE. : STEWARD (Statewide Transportation Engineering : Ware...

  9. Management and integration of engineering and construction activities: Lessons learned from the AP1000{sup R} nuclear power plant China project

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    McCullough, M. C.; Ebeling-Koning, D.; Evans, M. C.

    2012-07-01

    The lessons learned during the early phase of design engineering and construction activities for the AP1000 China Project can be applied to any project involving multiple disciplines and multiple organizations. Implementation of a first-of-a-kind design to directly support construction activities utilizing resources assigned to design development and design delivery creates challenges with prioritization of activities, successful closure of issues, and communication between site organizations and the home office. To ensure successful implementation, teams were assigned and developed to directly support construction activities including prioritization of activities, site communication and ensuring closure of site emergent issues. By developing these teams, themore » organization is better suited to meet the demands of the construction schedule while continuing with design evolution of a standard plant and engineering delivery for multiple projects. For a successful project, proper resource utilization and prioritization are key for overcoming obstacles and ensuring success of the engineering organization. (authors)« less

  10. Methodology discourses as boundary work in the construction of engineering education.

    PubMed

    Beddoes, Kacey

    2014-04-01

    Engineering education research is a new field that emerged in the social sciences over the past 10 years. This analysis of engineering education research demonstrates that methodology discourses have played a central role in the construction and development of the field of engineering education, and that they have done so primarily through boundary work. This article thus contributes to science and technology studies literature by examining the role of methodology discourses in an emerging social science field. I begin with an overview of engineering education research before situating the case within relevant bodies of literature on methodology discourses and boundary work. I then identify two methodology discourses--rigor and methodological diversity--and discuss how they contribute to the construction and development of engineering education research. The article concludes with a discussion of how the findings relate to prior research on methodology discourses and boundary work and implications for future research.

  11. AUTOMOTIVE DIESEL MAINTENANCE 1. UNIT XXIX, REVIEWING THE CONSTRUCTION OF ENGINE COMPONENTS.

    ERIC Educational Resources Information Center

    Human Engineering Inst., Cleveland, OH.

    THIS MODULE OF A 30-MODULE COURSE IS DESIGNED TO PROVIDE A REVIEW OF THE CONSTRUCTION AND OPERATION OF DIESEL ENGINE COMPONENTS. TOPICS ARE STATIONARY PARTS, ENGINE MOVING PARTS, PISTON RINGS, AND CONNECTING RODS AND PISTON PINS. THE MODULE CONSISTS OF AN INSTRUCTOR'S GUIDE, TRANSPARENCIES, A LIST OF SUGGESTED SUPPLEMENTARY MATERIALS, AND TRAINEE…

  12. Advancing Integrated STEM Learning through Engineering Design: Sixth-Grade Students' Design and Construction of Earthquake Resistant Buildings

    ERIC Educational Resources Information Center

    English, Lyn D.; King, Donna; Smeed, Joanna

    2017-01-01

    As part of a 3-year longitudinal study, 136 sixth-grade students completed an engineering-based problem on earthquakes involving integrated STEM learning. Students employed engineering design processes and STEM disciplinary knowledge to plan, sketch, then construct a building designed to withstand earthquake damage, taking into account a number of…

  13. Knowledge, attitude and practices for design for safety: A study on civil & structural engineers.

    PubMed

    Goh, Yang Miang; Chua, Sijie

    2016-08-01

    Design for safety (DfS) (also known as prevention through design, safe design and Construction (Design and Management)) promotes early consideration of safety and health hazards during the design phase of a construction project. With early intervention, hazards can be more effectively eliminated or controlled leading to safer worksites and construction processes. DfS is practiced in many countries, including Australia, the UK, and Singapore. In Singapore, the Manpower Ministry enacted the DfS Regulations in July 2015, which will be enforced from August 2016 onwards. Due to the critical role of civil and structural (C&S) engineers during design and construction, the DfS knowledge, attitude and practices (KAP) of C&S engineers have significant impact on the successful implementation of DfS. Thus, this study aims to explore the DfS KAP of C&S engineers so as to guide further research in measuring and improving DfS KAP of designers. During the study, it was found that there is a lack of KAP studies in construction management. Therefore, this study also aims to provide useful lessons for future applications of the KAP framework in construction management research. A questionnaire was developed to assess the DfS KAP of C&S engineers. The responses provided by 43 C&S engineers were analyzed. In addition, interviews with experienced construction professionals were carried out to further understand perceptions of DfS and related issues. The results suggest that C&S engineers are supportive of DfS, but the level of DfS knowledge and practices need to be improved. More DfS guidelines and training should be made available to the engineers. To ensure that DfS can be implemented successfully, there is a need to study the contractual arrangements between clients and designers and the effectiveness of different implementation approaches for the DfS process. The questionnaire and findings in this study provided the foundation for a baseline survey with larger sample size, which is currently being planned. In contrast to earlier studies, the study showed that the responding C&S engineers were supportive of the DfS. The study showed that the key to improving the DfS KAP of C&S engineers is by improving clients' motivation for DfS. Copyright © 2015 Elsevier Ltd. All rights reserved.

  14. 48 CFR 36.601-4 - Implementation.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... engineering nature associated with design or construction of real property. (3) Other professional services of..., investigations, surveying and mapping, tests, evaluations, consultations, comprehensive planning, program management, conceptual designs, plans and specifications, value engineering, construction phase services...

  15. 48 CFR 36.601-4 - Implementation.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... engineering nature associated with design or construction of real property. (3) Other professional services of..., investigations, surveying and mapping, tests, evaluations, consultations, comprehensive planning, program management, conceptual designs, plans and specifications, value engineering, construction phase services...

  16. 48 CFR 36.601-4 - Implementation.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... engineering nature associated with design or construction of real property. (3) Other professional services of..., investigations, surveying and mapping, tests, evaluations, consultations, comprehensive planning, program management, conceptual designs, plans and specifications, value engineering, construction phase services...

  17. 48 CFR 36.601-4 - Implementation.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... engineering nature associated with design or construction of real property. (3) Other professional services of..., investigations, surveying and mapping, tests, evaluations, consultations, comprehensive planning, program management, conceptual designs, plans and specifications, value engineering, construction phase services...

  18. 48 CFR 36.601-4 - Implementation.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... engineering nature associated with design or construction of real property. (3) Other professional services of..., investigations, surveying and mapping, tests, evaluations, consultations, comprehensive planning, program management, conceptual designs, plans and specifications, value engineering, construction phase services...

  19. Construction engineering inspection direct cost survey.

    DOT National Transportation Integrated Search

    2014-07-01

    The objective of the study was to provide a rationale to Georgia Department of Transportation : (GDOT) for Direct Costs in terms of salary and wages charged by qualified independent : contractors performing Construction Engineering Inspection (CEI) s...

  20. 14 CFR 23.1193 - Cowling and nacelle.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ...) Each cowling must be constructed and supported so that it can resist any vibration, inertia, and air... engines must be designed and constructed so that with the landing gear retracted, a fire in the engine...

  1. Purpose-driven biomaterials research in liver-tissue engineering.

    PubMed

    Ananthanarayanan, Abhishek; Narmada, Balakrishnan Chakrapani; Mo, Xuejun; McMillian, Michael; Yu, Hanry

    2011-03-01

    Bottom-up engineering of microscale tissue ("microtissue") constructs to recapitulate partially the complex structure-function relationships of liver parenchyma has been realized through the development of sophisticated biomaterial scaffolds, liver-cell sources, and in vitro culture techniques. With regard to in vivo applications, the long-lived stem/progenitor cell constructs can improve cell engraftment, whereas the short-lived, but highly functional hepatocyte constructs stimulate host liver regeneration. With regard to in vitro applications, microtissue constructs are being adapted or custom-engineered into cell-based assays for testing acute, chronic and idiosyncratic toxicities of drugs or pathogens. Systems-level methods and computational models that represent quantitative relationships between biomaterial scaffolds, cells and microtissue constructs will further enable their rational design for optimal integration into specific biomedical applications. Copyright © 2010 Elsevier Ltd. All rights reserved.

  2. Virginia's mowing experiments.

    DOT National Transportation Integrated Search

    1981-01-01

    With construction of the interstate and arterial highway systems nearing completion, the Department's major concern has shifted to maintenance. Because the highways must be maintained to very high standards, the reduced buying power means that frugal...

  3. Towards organ printing: engineering an intra-organ branched vascular tree.

    PubMed

    Visconti, Richard P; Kasyanov, Vladimir; Gentile, Carmine; Zhang, Jing; Markwald, Roger R; Mironov, Vladimir

    2010-03-01

    Effective vascularization of thick three-dimensional engineered tissue constructs is a problem in tissue engineering. As in native organs, a tissue-engineered intra-organ vascular tree must be comprised of a network of hierarchically branched vascular segments. Despite this requirement, current tissue-engineering efforts are still focused predominantly on engineering either large-diameter macrovessels or microvascular networks. We present the emerging concept of organ printing or robotic additive biofabrication of an intra-organ branched vascular tree, based on the ability of vascular tissue spheroids to undergo self-assembly. The feasibility and challenges of this robotic biofabrication approach to intra-organ vascularization for tissue engineering based on organ-printing technology using self-assembling vascular tissue spheroids including clinically relevantly vascular cell sources are analyzed. It is not possible to engineer 3D thick tissue or organ constructs without effective vascularization. An effective intra-organ vascular system cannot be built by the simple connection of large-diameter vessels and microvessels. Successful engineering of functional human organs suitable for surgical implantation will require concomitant engineering of a 'built in' intra-organ branched vascular system. Organ printing enables biofabrication of human organ constructs with a 'built in' intra-organ branched vascular tree.

  4. Mineralization Induction of Gingival Fibroblasts and Construction of a Sandwich Tissue-Engineered Complex for Repairing Periodontal Defects

    PubMed Central

    Wu, Mingxuan; Zhang, Yanning; Liu, Huijuan; Dong, Fusheng

    2018-01-01

    Background The ideal healing technique for periodontal tissue defects would involve the functional regeneration of the alveolar bone, cementum, and periodontal ligament, with new periodontal attachment formation. In this study, gingival fibroblasts were induced and a “sandwich” tissue-engineered complex (a tissue-engineered periodontal membrane between 2 tissue-engineered mineralized membranes) was constructed to repair periodontal defects. We evaluated the effects of gingival fibroblasts used as seed cells on the repair of periodontal defects and periodontal regeneration. Material/Methods Primitively cultured gingival fibroblasts were seeded bilaterally on Bio-Gide collagen membrane (a tissue-engineered periodontal membrane) or unilaterally on small intestinal submucosa segments, and their mineralization was induced. A tissue-engineered sandwich was constructed, comprising the tissue-engineered periodontal membrane flanked by 2 mineralized membranes. Periodontal defects in premolar regions of Beagles were repaired using the tissue-engineered sandwich or periodontal membranes. Periodontal reconstruction was compared to normal and trauma controls 10 or 20 days postoperatively. Results Periodontal defects were completely repaired by the sandwich tissue-engineered complex, with intact new alveolar bone and cementum, and a new periodontal ligament, 10 days postoperatively. Conclusions The sandwich tissue-engineered complex can achieve ideal periodontal reconstruction rapidly. PMID:29470454

  5. Elementary wave interactions in blood flow through artery

    NASA Astrophysics Data System (ADS)

    Raja Sekhar, T.; Minhajul

    2017-10-01

    In this paper, we consider the Riemann problem and interaction of elementary waves for the quasilinear hyperbolic system of conservation laws that arises in blood flow through arteries. We study the properties of solution involving shocks and rarefaction waves and establish the existence and uniqueness conditions. We show that the Riemann problem is solvable for arbitrary initial data under certain condition and construct the condition for no-feasible solution. Finally, we present numerical examples with different initial data and discuss all possible interactions of elementary waves.

  6. An Exploratory Study of Students' Constructions of Gender in Science, Engineering and Technology

    ERIC Educational Resources Information Center

    Lynch, Ingrid; Nowosenetz, Tessa

    2009-01-01

    Despite an appreciation of the need to increase gender sensitivity and awareness among tertiary students in the field of science, engineering and technology (SET), there is a paucity of research that explores how students in this field construct gender. A greater understanding of such constructions can assist in transforming gender relations and…

  7. Assessing Students' Sentiments towards the Use of a Building Information Modelling (BIM) Learning Platform in a Construction Project Management Course

    ERIC Educational Resources Information Center

    Suwal, Sunil; Singh, Vishal

    2018-01-01

    Building Information Modelling (BIM) tools and processes are increasingly adopted and implemented in the construction industry. Consequently, BIM education is considered increasingly important in Architecture, Engineering and Construction (AEC) education. While most of the research and literature on BIM education in engineering studies has focused…

  8. An Analysis of Insulated Concrete Forms for use in Sustainable Military Construction

    DTIC Science & Technology

    2014-03-27

    CONSTRUCTION THESIS Presented to the Faculty Department of Systems and Engineering Management Graduate School of Engineering and Management...which fit together and are filled with reinforced concrete to construct the exterior wall systems of a building. By design, this material provides a...Forms with Rebar .............................................................. 12 Figure 3. Cut outs of ICF wall systems

  9. Identifying Indicators Related to Constructs for Engineering Design Outcome

    ERIC Educational Resources Information Center

    Wilhelmsen, Cheryl A.; Dixon, Raymond A.

    2016-01-01

    This study ranked constructs articulated by Childress and Rhodes (2008) and identified the key indicators for each construct as a starting point to explore what should be included on an instrument to measure the engineering design process and outcomes of students in high schools that use the PLTW and EbDTM curricula in Idaho. A case-study design…

  10. REACTOR SERVICE BUILDING, TRA635, CONTEXTUAL VIEW DURING CONSTRUCTION. CAMERA IS ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    REACTOR SERVICE BUILDING, TRA-635, CONTEXTUAL VIEW DURING CONSTRUCTION. CAMERA IS ATOP MTR BUILDING AND LOOKING SOUTHERLY. FOUNDATION AND DRAINS ARE UNDER CONSTRUCTION. THE BUILDING WILL BUTT AGAINST CHARGING FACE OF PLUG STORAGE BUILDING. HOT CELL BUILDING, TRA-632, IS UNDER CONSTRUCTION AT TOP CENTER OF VIEW. INL NEGATIVE NO. 8518. Unknown Photographer, 8/25/1953 - Idaho National Engineering Laboratory, Test Reactor Area, Materials & Engineering Test Reactors, Scoville, Butte County, ID

  11. Final Report on the Audit of Architect-Engineer Contracting at the Officer in Charge of Construction, Naval Facilities Engineering Command Contracts, Mediterranean, Madrid, Spain

    DTIC Science & Technology

    1990-11-30

    This is our final report on the audit of Architect-Engineer Contracting for the Officer in Charge of Construction, Naval Facilities Engineering...Command Contracts, Mediterranean, for your information and use. This is the fourth in a series of reports issued as part of the audit of architect-engineer...A-E) contracting. The Contract Management Directorate made the audit from August 1989 through July 1990. When we expanded the audit scope to include

  12. River Engineers on the Middle Mississippi: A History of the St. Louis District, U.S. Army Corps of Engineers

    DTIC Science & Technology

    1978-01-01

    consequently accelerating the drainage of surface water into the Mississippi and its tributaries. 16 77 Although he considered levees responsible for the ...creation of the Mississippi River Commission in 1879. Its assigned functions included making surveys, plans, and estimates for improve- ments to "correct...along those great transportation arteries, St. Louis continues to depend on waterborne commerce for a large measure

  13. Antishear Stress Bionic Carbon Nanotube Mesh Coating with Intracellular Controlled Drug Delivery Constructing Small-Diameter Tissue-Engineered Vascular Grafts.

    PubMed

    Ding, Ning; Dou, Ce; Wang, Yuxin; Liu, Feila; Guan, Ge; Huo, Da; Li, Yanzhao; Yang, Jingyuan; Wei, Keyu; Yang, Mingcan; Tan, Ju; Zeng, Wen; Zhu, Chuhong

    2018-06-01

    Small-diameter (<6 mm) tissue-engineered blood vessels (TEBVs) have a low patency rate due to chronic inflammation mediated intimal hyperplasia. Functional coating with drug release is a promising solution, but preventing the released drug from being rushed away by blood flow remains a great challenge. A single-walled carboxylic acid functionalized carbon nanotube (C-SWCNT) is used to build an irregular mesh for TEBV coating. However, an interaction between the released drug and the cells is still insufficient due to the blood flow. Thus, an intracellular drug delivery system mediated by macrophage cellular uptake is designed. Resveratrol (RSV) modified CNT is used for macrophage uptake. M1 macrophage uptakes CNT-RSV and then converts to the M2 phenotype upon intracellular RSV release. Prohealing M2 macrophage inhibits the chronic inflammation thus maintains the contractile phenotype of the vascular smooth muscle cell (VSMC), which reduces intimal hyperplasia. Additionally, RSV released from the mesh coating also directly protects the contractile VSMCs from being converted to a secretory phenotype. Through antishear stress coating and macrophage-based intracellular drug delivery, CNT-RSV TEBVs exhibit a long-term anti-intimal hyperplasia function. Animal transplantation studies show that the patency rate remains high until day 90 after grafting in rat carotid arteries. © 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  14. A Cost-Effective Culture System for the In Vitro Assembly, Maturation, and Stimulation of Advanced Multilayered Multiculture Tubular Tissue Models.

    PubMed

    Loy, Caroline; Pezzoli, Daniele; Candiani, Gabriele; Mantovani, Diego

    2018-01-01

    The development of tubular engineered tissues is a challenging research area aiming to provide tissue substitutes but also in vitro models to test drugs, medical devices, and even to study physiological and pathological processes. In this work, the design, fabrication, and validation of an original cost-effective tubular multilayered-tissue culture system (TMCS) are reported. By exploiting cellularized collagen gel as scaffold, a simple moulding technique and an endothelialization step on a rotating system, TMCS allowed to easily prepare in 48 h, trilayered arterial wall models with finely organized cellular composition and to mature them for 2 weeks without any need of manipulation. Multilayered constructs incorporating different combinations of vascular cells are compared in terms of cell organization and viscoelastic mechanical properties demonstrating that cells always progressively aligned parallel to the longitudinal direction. Also, fibroblast compacted less the collagen matrix and appeared crucial in term of maturation/deposition of elastic extracellular matrix. Preliminary studies under shear stress stimulation upon connection with a flow bioreactor are successfully conducted without damaging the endothelial monolayer. Altogether, the TMCS herein developed, thanks to its versatility and multiple functionalities, holds great promise for vascular tissue engineering applications, but also for other tubular tissues such as trachea or oesophagus. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  15. The peripheral artery questionnaire: a new disease-specific health status measure for patients with peripheral arterial disease.

    PubMed

    Spertus, John; Jones, Philip; Poler, Sherri; Rocha-Singh, Krishna

    2004-02-01

    The most common indication for treating patients with peripheral arterial disease is to improve their health status: their symptoms, function, and quality of life. Quantifying health status requires a valid, reproducible, and sensitive disease-specific measure. The Peripheral Artery Questionnaire (PAQ) is a 20-item questionnaire developed to meet this need by quantifying patients' physical limitations, symptoms, social function, treatment satisfaction, and quality of life. Psychometric and clinical properties of the PAQ were evaluated in a prospective cohort study of 44 patients undergoing elective percutaneous peripheral revascularization. To establish reproducibility, 2 assessments were performed 2 weeks apart and before revascularization. The change in scores before and 6 weeks after revascularization were used to determine the instruments' responsiveness and were compared with the Short Form-36 and the Walking Impairment Questionnaire. A series of cross-sectional analyses were performed to establish the construct validity of the PAQ. The 7 domains of the PAQ were internally reliable, with Cronbach alpha = 0.80 to 0.94. The test-retest reliability analyses revealed insignificant mean changes of 0.6 to 2.3 points (P = not significant for all). Conversely, the change after revascularization ranged from 13.7 to 41.9 points (P < or =.001 for all), reflecting substantial sensitivity of the PAQ to clinical improvement. The PAQ Summary Scale was the most sensitive of all scales tested. Construct validity was established by demonstrating correlations with other measures of patient health status. The PAQ is a valid, reliable, and responsive disease-specific measure for patients with peripheral arterial disease. It may prove to be a useful end point in clinical trials and a potential aid in disease management.

  16. Developing safety risk index for truck preferred arterial corridor.

    DOT National Transportation Integrated Search

    2013-06-01

    Truck safety has been of great interest to transportation officials, engineers and researchers for many years because : of the amount of freight transported by trucks, the safety impact of trucks in traffic, and trucks invaluable : contribution to...

  17. 58. Photographic copy of original construction plan (St. Paul Engineer's ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    58. Photographic copy of original construction plan (St. Paul Engineer's Office, Wabasha St. Bridge, Plan of Masonry, February 1899); south abutment - Wabasha Street Bridge, Spanning Mississippi River at Wabasha Street, Saint Paul, Ramsey County, MN

  18. Railway project design and construction (CEE 411) course updates.

    DOT National Transportation Integrated Search

    2017-01-20

    Course CEE 411 "Railway Project Design and Construction" is a cornerstone of the railway : engineering education program developed by the Rail Transportation and Engineering Center : (RailTEC) at the University of Illinois at Urbana-Champaign (UIUC)....

  19. Fibrin gels exhibit improved biological, structural, and mechanical properties compared with collagen gels in cell-based tendon tissue-engineered constructs.

    PubMed

    Breidenbach, Andrew P; Dyment, Nathaniel A; Lu, Yinhui; Rao, Marepalli; Shearn, Jason T; Rowe, David W; Kadler, Karl E; Butler, David L

    2015-02-01

    The prevalence of tendon and ligament injuries and inadequacies of current treatments is driving the need for alternative strategies such as tissue engineering. Fibrin and collagen biopolymers have been popular materials for creating tissue-engineered constructs (TECs), as they exhibit advantages of biocompatibility and flexibility in construct design. Unfortunately, a few studies have directly compared these materials for tendon and ligament applications. Therefore, this study aims at determining how collagen versus fibrin hydrogels affect the biological, structural, and mechanical properties of TECs during formation in vitro. Our findings show that tendon and ligament progenitor cells seeded in fibrin constructs exhibit improved tenogenic gene expression patterns compared with their collagen-based counterparts for approximately 14 days in culture. Fibrin-based constructs also exhibit improved cell-derived collagen alignment, increased linear modulus (2.2-fold greater) compared with collagen-based constructs. Cyclic tensile loading, which promotes the maturation of tendon constructs in a previous work, exhibits a material-dependent effect in this study. Fibrin constructs show trending reductions in mechanical, biological, and structural properties, whereas collagen constructs only show improved tenogenic expression in the presence of mechanical stimulation. These findings highlight that components of the mechanical stimulus (e.g., strain amplitude or time of initiation) need to be tailored to the material and cell type. Given the improvements in tenogenic expression, extracellular matrix organization, and material properties during static culture, in vitro findings presented here suggest that fibrin-based constructs may be a more suitable alternative to collagen-based constructs for tissue-engineered tendon/ligament repair.

  20. Fibrin Gels Exhibit Improved Biological, Structural, and Mechanical Properties Compared with Collagen Gels in Cell-Based Tendon Tissue-Engineered Constructs

    PubMed Central

    Dyment, Nathaniel A.; Lu, Yinhui; Rao, Marepalli; Shearn, Jason T.; Rowe, David W.; Kadler, Karl E.; Butler, David L.

    2015-01-01

    The prevalence of tendon and ligament injuries and inadequacies of current treatments is driving the need for alternative strategies such as tissue engineering. Fibrin and collagen biopolymers have been popular materials for creating tissue-engineered constructs (TECs), as they exhibit advantages of biocompatibility and flexibility in construct design. Unfortunately, a few studies have directly compared these materials for tendon and ligament applications. Therefore, this study aims at determining how collagen versus fibrin hydrogels affect the biological, structural, and mechanical properties of TECs during formation in vitro. Our findings show that tendon and ligament progenitor cells seeded in fibrin constructs exhibit improved tenogenic gene expression patterns compared with their collagen-based counterparts for approximately 14 days in culture. Fibrin-based constructs also exhibit improved cell-derived collagen alignment, increased linear modulus (2.2-fold greater) compared with collagen-based constructs. Cyclic tensile loading, which promotes the maturation of tendon constructs in a previous work, exhibits a material-dependent effect in this study. Fibrin constructs show trending reductions in mechanical, biological, and structural properties, whereas collagen constructs only show improved tenogenic expression in the presence of mechanical stimulation. These findings highlight that components of the mechanical stimulus (e.g., strain amplitude or time of initiation) need to be tailored to the material and cell type. Given the improvements in tenogenic expression, extracellular matrix organization, and material properties during static culture, in vitro findings presented here suggest that fibrin-based constructs may be a more suitable alternative to collagen-based constructs for tissue-engineered tendon/ligament repair. PMID:25266738

  1. Mechanics of oriented electrospun nanofibrous scaffolds for annulus fibrosus tissue engineering.

    PubMed

    Nerurkar, Nandan L; Elliott, Dawn M; Mauck, Robert L

    2007-08-01

    Engineering a functional replacement for the annulus fibrosus (AF) of the intervertebral disc is contingent upon recapitulation of AF structure, composition, and mechanical properties. In this study, we propose a new paradigm for AF tissue engineering that focuses on the reconstitution of anatomic fiber architecture and uses constitutive modeling to evaluate construct function. A modified electrospinning technique was utilized to generate aligned nanofibrous polymer scaffolds for engineering the basic functional unit of the AF, a single lamella. Scaffolds were tested in uniaxial tension at multiple fiber orientations, demonstrating a nonlinear dependence of modulus on fiber angle that mimicked the nonlinearity and anisotropy of native AF. A homogenization model previously applied to native AF successfully described scaffold mechanical response, and parametric studies demonstrated that nonfibrillar matrix, along with fiber connectivity, are key contributors to tensile mechanics for engineered AF. We demonstrated that AF cells orient themselves along the aligned scaffolds and deposit matrix that contributes to construct mechanics under loading conditions relevant to the in vivo environment. The homogenization model was applied to cell-seeded constructs and provided quantitative measures for the evolution of matrix and interfibrillar interactions. Finally, the model demonstrated that at fiber angles of the AF (28 degrees -44 degrees ), engineered material behaved much like native tissue, suggesting that engineered constructs replicate the physiologic behavior of the single AF lamella. Constitutive modeling provides a powerful tool for analysis of engineered AF neo-tissue and native AF tissue alike, highlighting key mechanical design criteria for functional AF tissue engineering.

  2. Constructively Aligned Teaching and Learning in Higher Education in Engineering: What Do Students Perceive as Contributing to the Learning of Interdisciplinary Thinking?

    ERIC Educational Resources Information Center

    Spelt, E. J. H.; Luning, P. A.; van Boekel, M. A. J. S.; Mulder, M.

    2015-01-01

    Increased attention to the need for constructively aligned teaching and learning in interdisciplinary higher education in engineering is observed. By contrast, little research has been conducted on the implementation of the outcome-based pedagogical approach to interdisciplinary higher education in engineering. Therefore, the present design-based…

  3. The Expanding World of Tissue Engineering: The Building Blocks and New Applications of Tissue Engineered Constructs

    PubMed Central

    Zorlutuna, Pinar; Vrana, Nihal Engin; Khademhosseini, Ali

    2013-01-01

    The field of tissue engineering has been growing in the recent years as more products have made it to the market and as new uses for the engineered tissues have emerged, motivating many researchers to engage in this multidisciplinary field of research. Engineered tissues are now not only considered as end products for regenerative medicine, but also have emerged as enabling technologies for other fields of research ranging from drug discovery to biorobotics. This widespread use necessitates a variety of methodologies for production of tissue engineered constructs. In this review, these methods together with their non-clinical applications will be described. First, we will focus on novel materials used in tissue engineering scaffolds; such as recombinant proteins and synthetic, self assembling polypeptides. The recent advances in the modular tissue engineering area will be discussed. Then scaffold-free production methods, based on either cell sheets or cell aggregates will be described. Cell sources used in tissue engineering and new methods that provide improved control over cell behavior such as pathway engineering and biomimetic microenvironments for directing cell differentiation will be discussed. Finally, we will summarize the emerging uses of engineered constructs such as model tissues for drug discovery, cancer research and biorobotics applications. PMID:23268388

  4. This photographic copy of an engineering drawing shows floor plans, ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    This photographic copy of an engineering drawing shows floor plans, sections and elevations of Building E-86, with details typical of the steel frame and "Transite" building construction at JPL Edwards Facility. California Institute of Technology, Jet Propulsion Laboratory, Facilities Engineering and Construction Office: "Casting & Curing, Building E-86, Floor Plan, Elevations & Section," drawing no. E86/6, 25 February 1977. California Institute of Technology, Jet Propulsion Laboratory, Plant Engineering: engineering drawings of structures at JPL Edwards Facility. Drawings on file at JPL Plant Engineering, Pasadena, California - Jet Propulsion Laboratory Edwards Facility, Casting & Curing Building, Edwards Air Force Base, Boron, Kern County, CA

  5. 10 CFR 609.12 - Project Costs.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... incurred in the design, engineering, financing, construction, startup, commissioning and shakedown of the... rental of real property, including engineering fees, surveys, title insurance, recording fees, and legal... transportation for facility design, construction, startup, commissioning and shakedown; (3) Costs of equipment...

  6. 10 CFR 609.12 - Project Costs.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... incurred in the design, engineering, financing, construction, startup, commissioning and shakedown of the... rental of real property, including engineering fees, surveys, title insurance, recording fees, and legal... transportation for facility design, construction, startup, commissioning and shakedown; (3) Costs of equipment...

  7. 10 CFR 609.12 - Project Costs.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... incurred in the design, engineering, financing, construction, startup, commissioning and shakedown of the... rental of real property, including engineering fees, surveys, title insurance, recording fees, and legal... transportation for facility design, construction, startup, commissioning and shakedown; (3) Costs of equipment...

  8. 10 CFR 609.12 - Project Costs.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... incurred in the design, engineering, financing, construction, startup, commissioning and shakedown of the... rental of real property, including engineering fees, surveys, title insurance, recording fees, and legal... transportation for facility design, construction, startup, commissioning and shakedown; (3) Costs of equipment...

  9. 10 CFR 609.12 - Project Costs.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... incurred in the design, engineering, financing, construction, startup, commissioning and shakedown of the... rental of real property, including engineering fees, surveys, title insurance, recording fees, and legal... transportation for facility design, construction, startup, commissioning and shakedown; (3) Costs of equipment...

  10. The influence of construct scale on the composition and functional properties of cartilaginous tissues engineered using bone marrow-derived mesenchymal stem cells.

    PubMed

    Buckley, Conor T; Meyer, Eric G; Kelly, Daniel J

    2012-02-01

    Engineering cartilaginous tissue of a scale necessary to treat defects observed clinically is a well-documented challenge in the field of cartilage tissue engineering. The objective of this study was to determine how the composition and mechanical properties of cartilaginous tissues that are engineered by using bone marrow-derived mesenchymal stem cells (MSCs) depend on the scale of the construct. Porcine bone marrow-derived MSCs were encapsulated in agarose hydrogels, and constructs of different cylindrical geometries (Ø4×1.5 mm; Ø5×3 mm; Ø6×4.5 mm; Ø8×4.5 mm) were fabricated and maintained in a chemically defined serum-free medium supplemented with transforming growth factor-β3 for 42 days. Total sulfated glycosaminoglycan (sGAG) accumulation by day 42 increased from 0.14% w/w to 0.88% w/w as the construct geometry increased from Ø4×1.5 to Ø8×4.5 mm, with collagen accumulation increasing from 0.31% w/w to 1.62% w/w. This led to an increase in the dynamic modulus from 90.81 to 327.51 kPa as the engineered tissue increased in scale from Ø4×1.5 to Ø8×4.5 mm. By decreasing the external oxygen tension from 20% to 5%, it was possible to achieve these higher levels of mechanical functionality in the smaller engineered tissues. Constructs were then sectioned into smaller subregions to quantify the spatial accumulation of extracellular matrix components, and a model of oxygen diffusion and consumption was used to predict spatial gradients in oxygen concentration throughout the construct. sGAG accumulation was always highest in regions where oxygen concentration was predicted to be lowest. In addition, as the size of the engineered construct increased, different regions of the construct preferentially supported either sGAG or collagen accumulation, thus suggesting that gradients in regulatory factors other than oxygen were playing a role in determining levels of collagen synthesis. The identification of such factors and the means to control their spatial concentration within developing tissues represents a central challenge in engineering large cartilaginous grafts.

  11. Towards Additive Manufacture of Functional, Spline-Based Morphometric Models of Healthy and Diseased Coronary Arteries: In Vitro Proof-of-Concept Using a Porcine Template.

    PubMed

    Jewkes, Rachel; Burton, Hanna E; Espino, Daniel M

    2018-02-02

    The aim of this study is to assess the additive manufacture of morphometric models of healthy and diseased coronary arteries. Using a dissected porcine coronary artery, a model was developed with the use of computer aided engineering, with splines used to design arteries in health and disease. The model was altered to demonstrate four cases of stenosis displaying varying severity, based on published morphometric data available. Both an Objet Eden 250 printer and a Solidscape 3Z Pro printer were used in this analysis. A wax printed model was set into a flexible thermoplastic and was valuable for experimental testing with helical flow patterns observed in healthy models, dominating the distal LAD (left anterior descending) and left circumflex arteries. Recirculation zones were detected in all models, but were visibly larger in the stenosed cases. Resin models provide useful analytical tools for understanding the spatial relationships of blood vessels, and could be applied to preoperative planning techniques, but were not suitable for physical testing. In conclusion, it is feasible to develop blood vessel models enabling experimental work; further, through additive manufacture of bio-compatible materials, there is the possibility of manufacturing customized replacement arteries.

  12. Towards Additive Manufacture of Functional, Spline-Based Morphometric Models of Healthy and Diseased Coronary Arteries: In Vitro Proof-of-Concept Using a Porcine Template

    PubMed Central

    Jewkes, Rachel; Burton, Hanna E.; Espino, Daniel M.

    2018-01-01

    The aim of this study is to assess the additive manufacture of morphometric models of healthy and diseased coronary arteries. Using a dissected porcine coronary artery, a model was developed with the use of computer aided engineering, with splines used to design arteries in health and disease. The model was altered to demonstrate four cases of stenosis displaying varying severity, based on published morphometric data available. Both an Objet Eden 250 printer and a Solidscape 3Z Pro printer were used in this analysis. A wax printed model was set into a flexible thermoplastic and was valuable for experimental testing with helical flow patterns observed in healthy models, dominating the distal LAD (left anterior descending) and left circumflex arteries. Recirculation zones were detected in all models, but were visibly larger in the stenosed cases. Resin models provide useful analytical tools for understanding the spatial relationships of blood vessels, and could be applied to preoperative planning techniques, but were not suitable for physical testing. In conclusion, it is feasible to develop blood vessel models enabling experimental work; further, through additive manufacture of bio-compatible materials, there is the possibility of manufacturing customized replacement arteries. PMID:29393899

  13. The vascularization of a gastric tube as a substitute for the esophagus is affected by its diameter.

    PubMed

    Pierie, J P; de Graaf, P W; van Vroonhoven, T J; Obertop, H

    1998-10-01

    The stomach is used for reconstruction of the upper gastrointestinal tract after esophageal resection for cancer. The whole stomach can be used, but also a wide or narrow gastric tube can be constructed. Short-term functional results are superior after use of a narrow tube. Healing of the cervical esophagogastrostomy can be impaired, leading to leakage and stricture. The decreased vascularization at the site of the anastomosis may be one reason. It was hypothesized that the quality of the vascularization of the gastric tube, used as a substitute for the oesophagus after esophagectomy, depends on its diameter. The vascularization of postmortem specimens was studied using angiography. Whole stomachs (3), wide (3) and narrow gastric tubes (3) were constructed. In a patient with an anastomotic stricture of a narrow tube with a cervical esophagogastrostomy vascularisation was evaluated by angiography. After infusion of contrast through the supplying arteries, the whole stomachs and wide gastric tubes showed adequate vascularization, whereas the narrow gastric tube showed poor vascularization especially at the site of the anastomosis. In narrow gastric tubes, the right gastroepiploic artery was the only feeding artery. In the patient's angiography, a limited contrast visualization of the proximal end of the gastric tube could be demonstrated. Although a narrow gastric tube is favoured by some surgeons, the use of whole stomach or a type of gastric tube with preservation of the right gastric artery may lead to a better anastomotic healing.

  14. Applying systems engineering principles to the development of transportation communication standards.

    DOT National Transportation Integrated Search

    2011-04-22

    Using traffic control devices and communications equipment to monitor and control arterials and freeways has brought with it new challenges and a demand for new skills to the transportation industry. Some of the challenges include integrating informa...

  15. [Influence of traffic restriction on road and construction fugitive dust].

    PubMed

    Tian, Gang; Li, Gang; Qin, Jian-Ping; Fan, Shou-Bin; Huang, Yu-Hu; Nie, Lei

    2009-05-15

    By monitoring the road and construction dust fall continuously during the "Good Luck Beijing" sport events, the reduction of road and construction dust fall caused by traffic restriction was studied. The contribution rate of road and construction dust to particulate matter of Beijing atmosphere environment, and the emission ratio of it to total local PM10 emission were analyzed. The results show that the traffic restriction reduces road and construction dust fall significantly. The dust fall average value of ring roads was 0.27 g x (m2 x d)(-1) in the "traffic restriction" period, and the values were 0.81 and 0.59 g x (m2 x d)(-1) 1 month and 7 days before. The dust fall average value of major arterial and minor arterial was 0.21 g x (m2 x d)(-1) in the "traffic restriction" period, and the values were 0.54 and 0.58 g x (m2 x d)(-1) 1 month and 7 days before. The roads emission reduced 60%-70% compared with before traffic restriction. The dust fall average values of civil architecture and utility architecture were 0.61 and 1.06 g x (m2 x d)(-1) in the "traffic restriction" period, and the values were 1.15 and 1.55 g x (m2 x d)(-1) 20 days before. The construction dust reduced 30%-47% compared with 20 days before traffic restriction. Road and construction dust emission are the main source of atmosphere particulate matter in Beijing, and its contribution to ambient PM10 concentration is 21%-36%. PM10 emitted from roads and constructions account for 42%-72% and 30%-51% of local emission while the local PM10 account for 50% and 70% of the total emission.

  16. The potential of 3-dimensional construct engineered from poly(lactic-co-glycolic acid)/fibrin hybrid scaffold seeded with bone marrow mesenchymal stem cells for in vitro cartilage tissue engineering.

    PubMed

    Abdul Rahman, Rozlin; Mohamad Sukri, Norhamiza; Md Nazir, Noorhidayah; Ahmad Radzi, Muhammad Aa'zamuddin; Zulkifly, Ahmad Hafiz; Che Ahmad, Aminudin; Hashi, Abdurezak Abdulahi; Abdul Rahman, Suzanah; Sha'ban, Munirah

    2015-08-01

    Articular cartilage is well known for its simple uniqueness of avascular and aneural structure that has limited capacity to heal itself when injured. The use of three dimensional construct in tissue engineering holds great potential in regenerating cartilage defects. This study evaluated the in vitro cartilaginous tissue formation using rabbit's bone marrow mesenchymal stem cells (BMSCs)-seeded onto poly(lactic-co-glycolic acid) PLGA/fibrin and PLGA scaffolds. The in vitro cartilaginous engineered constructs were evaluated by gross inspection, histology, cell proliferation, gene expression and sulphated glycosaminoglycan (sGAG) production at week 1, 2 and 3. After 3 weeks of culture, the PLGA/fibrin construct demonstrated gross features similar to the native tissue with smooth, firm and glistening appearance, superior histoarchitectural and better cartilaginous extracellular matrix compound in concert with the positive glycosaminoglycan accumulation on Alcian blue. Significantly higher cell proliferation in PLGA/fibrin construct was noted at day-7, day-14 and day-21 (p<0.05 respectively). Both constructs expressed the accumulation of collagen type II, collagen type IX, aggrecan and sox9, showed down-regulation of collagen type I as well as produced relative sGAG content with PLGA/fibrin construct exhibited better gene expression in all profiles and showed significantly higher relative sGAG content at each time point (p<0.05). This study suggested that with optimum in vitro manipulation, PLGA/fibrin when seeded with pluripotent non-committed BMSCs has the capability to differentiate into chondrogenic lineage and may serve as a prospective construct to be developed as functional tissue engineered cartilage. Copyright © 2015 Elsevier Ltd. All rights reserved.

  17. Engineering tubular bone using mesenchymal stem cell sheets and coral particles

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Geng, Wenxin; Ma, Dongyang; Yan, Xingrong

    Highlights: • We developed a novel engineering strategy to solve the limitations of bone grafts. • We fabricated tubular constructs using cell sheets and coral particles. • The composite constructs showed high radiological density and compressive strength. • These characteristics were similar to those of native bone. -- Abstract: The development of bone tissue engineering has provided new solutions for bone defects. However, the cell-scaffold-based approaches currently in use have several limitations, including low cell seeding rates and poor bone formation capacity. In the present study, we developed a novel strategy to engineer bone grafts using mesenchymal stem cell sheetsmore » and coral particles. Rabbit bone marrow mesenchymal stem cells were continuously cultured to form a cell sheet with osteogenic potential and coral particles were integrated into the sheet. The composite sheet was then wrapped around a cylindrical mandrel to fabricate a tubular construct. The resultant tubular construct was cultured in a spinner-flask bioreactor and subsequently implanted into a subcutaneous pocket in a nude mouse for assessment of its histological characteristics, radiological density and mechanical property. A similar construct assembled from a cell sheet alone acted as a control. In vitro observations demonstrated that the composite construct maintained its tubular shape, and exhibited higher radiological density, compressive strength and greater extracellular matrix deposition than did the control construct. In vivo experiments further revealed that new bone formed ectopically on the composite constructs, so that the 8-week explants of the composite sheets displayed radiological density similar to that of native bone. These results indicate that the strategy of using a combination of a cell sheet and coral particles has great potential for bone tissue engineering and repairing bone defects.« less

  18. Factors affecting the structure and maturation of human tissue engineered skeletal muscle.

    PubMed

    Martin, Neil R W; Passey, Samantha L; Player, Darren J; Khodabukus, Alastair; Ferguson, Richard A; Sharples, Adam P; Mudera, Vivek; Baar, Keith; Lewis, Mark P

    2013-07-01

    Tissue engineered skeletal muscle has great utility in experimental studies of physiology, clinical testing and its potential for transplantation to replace damaged tissue. Despite recent work in rodent tissue or cell lines, there is a paucity of literature concerned with the culture of human muscle derived cells (MDCs) in engineered constructs. Here we aimed to tissue engineer for the first time in the literature human skeletal muscle in self-assembling fibrin hydrogels and determine the effect of MDC seeding density and myogenic proportion on the structure and maturation of the constructs. Constructs seeded with 4 × 10(5) MDCs assembled to a greater extent than those at 1 × 10(5) or 2 × 10(5), and immunostaining revealed a higher fusion index and a higher density of myotubes within the constructs, showing greater structural semblance to in vivo tissue. These constructs primarily expressed perinatal and slow type I myosin heavy chain mRNA after 21 days in culture. In subsequent experiments MACS(®) technology was used to separate myogenic and non-myogenic cells from their heterogeneous parent population and these cells were seeded at varying myogenic (desmin +) proportions in fibrin based constructs. Only in the constructs seeded with 75% desmin + cells was there evidence of striations when immunostained for slow myosin heavy chain compared with constructs seeded with 10 or 50% desmin + cells. Overall, this work reveals the importance of cell number and myogenic proportions in tissue engineering human skeletal muscle with structural resemblance to in vivo tissue. Copyright © 2013 Elsevier Ltd. All rights reserved.

  19. Anatomically shaped tissue-engineered cartilage with tunable and inducible anticytokine delivery for biological joint resurfacing

    PubMed Central

    Moutos, Franklin T.; Glass, Katherine A.; Compton, Sarah A.; Ross, Alison K.; Gersbach, Charles A.; Estes, Bradley T.

    2016-01-01

    Biological resurfacing of entire articular surfaces represents an important but challenging strategy for treatment of cartilage degeneration that occurs in osteoarthritis. Not only does this approach require anatomically sized and functional engineered cartilage, but the inflammatory environment within an arthritic joint may also inhibit chondrogenesis and induce degradation of native and engineered cartilage. The goal of this study was to use adult stem cells to engineer anatomically shaped, functional cartilage constructs capable of tunable and inducible expression of antiinflammatory molecules, specifically IL-1 receptor antagonist (IL-1Ra). Large (22-mm-diameter) hemispherical scaffolds were fabricated from 3D woven poly(ε-caprolactone) (PCL) fibers into two different configurations and seeded with human adipose-derived stem cells (ASCs). Doxycycline (dox)-inducible lentiviral vectors containing eGFP or IL-1Ra transgenes were immobilized to the PCL to transduce ASCs upon seeding, and constructs were cultured in chondrogenic conditions for 28 d. Constructs showed biomimetic cartilage properties and uniform tissue growth while maintaining their anatomic shape throughout culture. IL-1Ra–expressing constructs produced nearly 1 µg/mL of IL-1Ra upon controlled induction with dox. Treatment with IL-1 significantly increased matrix metalloprotease activity in the conditioned media of eGFP-expressing constructs but not in IL-1Ra–expressing constructs. Our findings show that advanced textile manufacturing combined with scaffold-mediated gene delivery can be used to tissue engineer large anatomically shaped cartilage constructs that possess controlled delivery of anticytokine therapy. Importantly, these cartilage constructs have the potential to provide mechanical functionality immediately upon implantation, as they will need to replace a majority, if not the entire joint surface to restore function. PMID:27432980

  20. Raman fiberoptic probe for monitoring human tissue engineered oral mucosa constructs

    NASA Astrophysics Data System (ADS)

    Khmaladze, Alexander; Kuo, Shiuhyang; Okagbare, Paul; Marcelo, Cynthia L.; Feinberg, Stephen E.; Morris, Michael D.

    2013-02-01

    In oral and maxillofacial surgery, there is a need for tissue engineered constructs for dental implants, reconstructions due to trauma, oral cancer or congenital defects. A non-invasive quality monitoring of the fabrication of tissue engineered constructs during their production and implantation is a required component of any successful tissue engineering technique. We demonstrate the design and application of a Raman spectroscopic probe for rapid and noninvasive monitoring of Ex Vivo Produced Oral Mucosa Equivalent constructs (EVPOMEs). We conducted in vivo studies to identify Raman spectroscopic failure indicators for EVPOMEs (already developed in vitro), and found that Raman spectra of EVPOMEs exposed to thermal stress showed correlation of the band height ratio of CH2 deformation to phenylalanine ring breathing modes, providing a Raman metric to distinguish between viable and nonviable constructs. This is the first step towards the ultimate goal to design a stand-alone system, which will be usable in a clinical setting, as the data processing and analysis will be performed with minimal user intervention, based on already established and tested Raman spectroscopic indicators for EVPOMEs.

  1. Center for Space Construction

    NASA Technical Reports Server (NTRS)

    Su, Renjeng

    1998-01-01

    The Center for Space Construction (CSC) at University of Colorado at Boulder is one of eight University Space Engineering Research Centers established by NASA in 1988. The mission of the Center is to conduct research into space technology and to directly contribute to space engineering education. The Center reports to the Department of Aerospace Engineering Sciences and resides in the College of Engineering and Applied Sciences. The College has a long and successful track record of cultivating multi-disciplinary research and education programs. The Center for Space Construction represents prominent evidence of this record. The basic concept on which the Center was founded is the in-space construction of large space systems, such as space stations, interplanetary space vehicles, and extraterrestrial space structures. Since 1993, the scope of CSC research has evolved to include the design and construction of all spacecraft, large and small. With the broadened scope our research projects seek to impact the technological basis for spacecraft such as remote sensing satellites, communication satellites and other special-purpose spacecraft, as well as large space platforms. A summary of accomplishments, including student participation and degrees awarded, during the contract period is presented.

  2. A Robust Method to Generate Mechanically Anisotropic Vascular Smooth Muscle Cell Sheets for Vascular Tissue Engineering.

    PubMed

    Backman, Daniel E; LeSavage, Bauer L; Shah, Shivem B; Wong, Joyce Y

    2017-06-01

    In arterial tissue engineering, mimicking native structure and mechanical properties is essential because compliance mismatch can lead to graft failure and further disease. With bottom-up tissue engineering approaches, designing tissue components with proper microscale mechanical properties is crucial to achieve the necessary macroscale properties in the final implant. This study develops a thermoresponsive cell culture platform for growing aligned vascular smooth muscle cell (VSMC) sheets by photografting N-isopropylacrylamide (NIPAAm) onto micropatterned poly(dimethysiloxane) (PDMS). The grafting process is experimentally and computationally optimized to produce PNIPAAm-PDMS substrates optimal for VSMC attachment. To allow long-term VSMC sheet culture and increase the rate of VSMC sheet formation, PNIPAAm-PDMS surfaces were further modified with 3-aminopropyltriethoxysilane yielding a robust, thermoresponsive cell culture platform for culturing VSMC sheets. VSMC cell sheets cultured on patterned thermoresponsive substrates exhibit cellular and collagen alignment in the direction of the micropattern. Mechanical characterization of patterned, single-layer VSMC sheets reveals increased stiffness in the aligned direction compared to the perpendicular direction whereas nonpatterned cell sheets exhibit no directional dependence. Structural and mechanical anisotropy of aligned, single-layer VSMC sheets makes this platform an attractive microstructural building block for engineering a vascular graft to match the in vivo mechanical properties of native arterial tissue. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  3. Value engineering awareness study for sustainable construction in Malaysia

    NASA Astrophysics Data System (ADS)

    U, Fathoni; M, Zakaria C.; O, Rohayu C.

    2013-06-01

    Construction process has often been described as a highly complex process because of the number of disciplines involved during the conceptual, design and construction stage. With the emergence of latest technology and concern for environment, increasing attention in construction industry is given on sustainability. Balance in quality and sustainability has become a major challenge to the construction industry. This paper presents a study that has conducted to determine the acceptance and application of Value Engineering (VE) and Life Cycle Cost Analysis (LCCA) in Malaysia construction industry. A set of questionnaire have distributed to different practitioners in construction industry and the result has reflect the fact that the application of VE and LCCA are still very low.

  4. Combined chemical and structural signals of biomaterials synergistically activate cell-cell communications for improving tissue regeneration.

    PubMed

    Xu, Yachen; Peng, Jinliang; Dong, Xin; Xu, Yuhong; Li, Haiyan; Chang, Jiang

    2017-06-01

    Biomaterials are only used as carriers of cells in the conventional tissue engineering. Considering the multi-cell environment and active cell-biomaterial interactions in tissue regeneration process, in this study, structural signals of aligned electrospun nanofibers and chemical signals of bioglass (BG) ionic products in cell culture medium are simultaneously applied to activate fibroblast-endothelial co-cultured cells in order to obtain an improved skin tissue engineering construct. Results demonstrate that the combined biomaterial signals synergistically activate fibroblast-endothelial co-culture skin tissue engineering constructs through promotion of paracrine effects and stimulation of gap junctional communication between cells, which results in enhanced vascularization and extracellular matrix protein synthesis in the constructs. Structural signals of aligned electrospun nanofibers play an important role in stimulating both of paracrine and gap junctional communication while chemical signals of BG ionic products mainly enhance paracrine effects. In vivo experiments reveal that the activated skin tissue engineering constructs significantly enhance wound healing as compared to control. This study indicates the advantages of synergistic effects between different bioactive signals of biomaterials can be taken to activate communication between different types of cells for obtaining tissue engineering constructs with improved functions. Tissue engineering can regenerate or replace tissue or organs through combining cells, biomaterials and growth factors. Normally, for repairing a specific tissue, only one type of cells, one kind of biomaterials, and specific growth factors are used to support cell growth. In this study, we proposed a novel tissue engineering approach by simply using co-cultured cells and combined biomaterial signals. Using a skin tissue engineering model, we successfully proved that the combined biomaterial signals such as surface nanostructures and bioactive ions could synergistically stimulate the cell-cell communication in co-culture system through paracrine effects and gap junction activation, and regulated expression of growth factors and extracellular matrix proteins, resulting in an activated tissue engineering constructs that significantly enhanced skin regeneration. Copyright © 2017 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.

  5. 48 CFR 36.102 - Definitions.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... CONTRACTING CONSTRUCTION AND ARCHITECT-ENGINEER CONTRACTS General 36.102 Definitions. As used in this part— Contract is intended to refer to a contract for construction or a contract for architect-engineer services..., structural, electrical, mechanical, and fire protection), producing the technical specifications and drawings...

  6. 48 CFR 36.102 - Definitions.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... CONTRACTING CONSTRUCTION AND ARCHITECT-ENGINEER CONTRACTS General 36.102 Definitions. As used in this part— Contract is intended to refer to a contract for construction or a contract for architect-engineer services..., structural, electrical, mechanical, and fire protection), producing the technical specifications and drawings...

  7. 48 CFR 36.102 - Definitions.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... CONTRACTING CONSTRUCTION AND ARCHITECT-ENGINEER CONTRACTS General 36.102 Definitions. As used in this part— Contract is intended to refer to a contract for construction or a contract for architect-engineer services..., structural, electrical, mechanical, and fire protection), producing the technical specifications and drawings...

  8. 48 CFR 36.102 - Definitions.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... CONTRACTING CONSTRUCTION AND ARCHITECT-ENGINEER CONTRACTS General 36.102 Definitions. As used in this part— Contract is intended to refer to a contract for construction or a contract for architect-engineer services..., structural, electrical, mechanical, and fire protection), producing the technical specifications and drawings...

  9. 48 CFR 36.102 - Definitions.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... CONTRACTING CONSTRUCTION AND ARCHITECT-ENGINEER CONTRACTS General 36.102 Definitions. As used in this part— Contract is intended to refer to a contract for construction or a contract for architect-engineer services..., structural, electrical, mechanical, and fire protection), producing the technical specifications and drawings...

  10. 76 FR 35424 - Information Collection Requirements; Defense Federal Acquisition Regulation Supplement...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-06-17

    ... DEPARTMENT OF DEFENSE Defense Acquisition Regulations System Information Collection Requirements; Defense Federal Acquisition Regulation Supplement; Construction and Architect-Engineer Contracts AGENCY..., Construction and Architect-Engineer Contracts, and Related Clauses at DFARS 252.236; OMB Control Number 0704...

  11. Imaging Strategies for Tissue Engineering Applications

    PubMed Central

    Nam, Seung Yun; Ricles, Laura M.; Suggs, Laura J.

    2015-01-01

    Tissue engineering has evolved with multifaceted research being conducted using advanced technologies, and it is progressing toward clinical applications. As tissue engineering technology significantly advances, it proceeds toward increasing sophistication, including nanoscale strategies for material construction and synergetic methods for combining with cells, growth factors, or other macromolecules. Therefore, to assess advanced tissue-engineered constructs, tissue engineers need versatile imaging methods capable of monitoring not only morphological but also functional and molecular information. However, there is no single imaging modality that is suitable for all tissue-engineered constructs. Each imaging method has its own range of applications and provides information based on the specific properties of the imaging technique. Therefore, according to the requirements of the tissue engineering studies, the most appropriate tool should be selected among a variety of imaging modalities. The goal of this review article is to describe available biomedical imaging methods to assess tissue engineering applications and to provide tissue engineers with criteria and insights for determining the best imaging strategies. Commonly used biomedical imaging modalities, including X-ray and computed tomography, positron emission tomography and single photon emission computed tomography, magnetic resonance imaging, ultrasound imaging, optical imaging, and emerging techniques and multimodal imaging, will be discussed, focusing on the latest trends of their applications in recent tissue engineering studies. PMID:25012069

  12. Towards organ printing: engineering an intra-organ branched vascular tree

    PubMed Central

    Visconti, Richard P; Kasyanov, Vladimir; Gentile, Carmine; Zhang, Jing; Markwald, Roger R; Mironov, Vladimir

    2013-01-01

    Importance of the field Effective vascularization of thick three-dimensional engineered tissue constructs is a problem in tissue engineering. As in native organs, a tissue-engineered intra-organ vascular tree must be comprised of a network of hierarchically branched vascular segments. Despite this requirement, current tissue-engineering efforts are still focused predominantly on engineering either large-diameter macrovessels or microvascular networks. Areas covered in this review We present the emerging concept of organ printing or robotic additive biofabrication of an intra-organ branched vascular tree, based on the ability of vascular tissue spheroids to undergo self-assembly. What the reader will gain The feasibility and challenges of this robotic biofabrication approach to intra-organ vascularization for tissue engineering based on organ-printing technology using self-assembling vascular tissue spheroids including clinically relevantly vascular cell sources are analyzed. Take home message It is not possible to engineer 3D thick tissue or organ constructs without effective vascularization. An effective intra-organ vascular system cannot be built by the simple connection of large-diameter vessels and microvessels. Successful engineering of functional human organs suitable for surgical implantation will require concomitant engineering of a ‘built in’ intra-organ branched vascular system. Organ printing enables biofabrication of human organ constructs with a ‘built in’ intra-organ branched vascular tree. PMID:20132061

  13. Airfield construction (3rd revised and enlarged edition)

    NASA Astrophysics Data System (ADS)

    Goretskii, Leonid I.; Boguslavskii, Adol'f. M.; Serebrenikov, Vadim A.; Barzdo, V. I.; Leshchitskaia, T. P.; Polosin-Nikitin, S. M.

    The principal engineering aspects of airfield construction are discussed. In particular, attention is given to the fundamental principles and organizational aspects of airfield construction; excavation work and airfield layout; construction of drainage systems; foundations and pavements; and quality control and safety engineering. The discussion also covers the operation of various support plants, including concrete production and mixing, production of asphalt-concrete mixtures and organic binders, production of structural steel and reinforced concrete components, and operation of stone quarries and gravel pits.

  14. A STUDY ON THE APPLICATION OF VALUE ENGINEERING TO THE CONSTRUCTION INDUSTRY

    NASA Astrophysics Data System (ADS)

    Kemmochi, Sampei; Koizumi, Atsushi

    Value Engineering (VE), one of the effective management techniques to provide products and services, is focused as a measure to reduce the cost on public works, but its effectiveness as a management technique doesn't seem to be fully understood in the construction industry. This paper demonstrates aspects and issues of VE in construction industry by comparing with manufacturing industry, and to combat these, VE which is implemented in construction industry must be succinct and proposes methods to conduct it from the viewpoint of construction industry. At last, the place to go to for construction industry down the road regarding the VE adaptation is clarified.

  15. The experimental study of genetic engineering human neural stem cells mediated by lentivirus to express multigene.

    PubMed

    Cai, Pei-qiang; Tang, Xun; Lin, Yue-qiu; Martin, Oudega; Sun, Guang-yun; Xu, Lin; Yang, Yun-kang; Zhou, Tian-hua

    2006-02-01

    To explore the feasibility to construct genetic engineering human neural stem cells (hNSCs) mediated by lentivirus to express multigene in order to provide a graft source for further studies of spinal cord injury (SCI). Human neural stem cells from the brain cortex of human abortus were isolated and cultured, then gene was modified by lentivirus to express both green fluorescence protein (GFP) and rat neurotrophin-3 (NT-3); the transgenic expression was detected by the methods of fluorescence microscope, dorsal root ganglion of fetal rats and slot blot. Genetic engineering hNSCs were successfully constructed. All of the genetic engineering hNSCs which expressed bright green fluorescence were observed under the fluorescence microscope. The conditioned medium of transgenic hNSCs could induce neurite flourishing outgrowth from dorsal root ganglion (DRG). The genetic engineering hNSCs expressed high level NT-3 which could be detected by using slot blot. Genetic engineering hNSCs mediated by lentivirus can be constructed to express multigene successfully.

  16. Using Project Management Systems at the Construction Field Office

    DTIC Science & Technology

    1989-03-01

    instrumentation 13550 transportation control instrumentation 13600 solor energy systems 13700 wind energy systems 13800 building automation systems ...Engineering Research Laboratory AD-A207 077 Using Project Management Systems at the Construction Field Office by E. William East Jeffrey G. Kirby Automated...automated systems available, engineers at the construction fieid office (or resident office) are faced with the over- whelming task of choosing which

  17. Flood trends and river engineering on the Mississippi River system

    USGS Publications Warehouse

    Pinter, N.; Jemberie, A.A.; Remo, J.W.F.; Heine, R.A.; Ickes, B.S.

    2008-01-01

    Along >4000 km of the Mississippi River system, we document that climate, land-use change, and river engineering have contributed to statistically significant increases in flooding over the past 100-150 years. Trends were tested using a database of >8 million hydrological measurements. A geospatial database of historical engineering construction was used to quantify the response of flood levels to each unit of engineering infrastructure. Significant climate- and/or land use-driven increases in flow were detected, but the largest and most pervasive contributors to increased flooding on the Mississippi River system were wing dikes and related navigational structures, followed by progressive levee construction. In the area of the 2008 Upper Mississippi flood, for example, about 2 m of the flood crest is linked to navigational and flood-control engineering. Systemwide, large increases in flood levels were documented at locations and at times of wing-dike and levee construction. Copyright 2008 by the American Geophysical Union.

  18. Reducing the risk of fatal and disabling hypoglycaemia: a comparison of arterial blood sampling systems.

    PubMed

    Brennan, K A; Eapen, G; Turnbull, D

    2010-04-01

    In 2008, the National Patient Safety Agency (NPSA) published a report after 42 incidents and two deaths where glucose-containing flush solutions were attached to the arterial line. The molar concentration of 5% glucose is 277 mmol litre(-1). Only a tiny amount of sample contamination will lead to an artificially high glucose. As the NPSA sought a solution, a bench model was constructed to compare the performance of three open and three closed arterial line systems in limiting sample contamination. All arterial line systems were set up in a standard manner and pressurized to 300 mm Hg with 5% glucose used as the flush solution. This was connected to the 'radial artery' using an 18 G needle representing the radial cannula. The radial artery was simulated using a wide-bore extension set with 'blood' flow at 60 ml min(-1). Blood was simulated by the addition of red dye to Hartmann's solution. Increasing multiples of arterial line dead space were aspirated and discarded. Blood samples were then obtained and glucose concentration was measured. Significant glucose contamination (3 mmol litre(-1) +/-3.4) was detected in all open arterial line systems up to an aspiration volume of five times the dead space. No samples from the closed systems recorded glucose concentration >1 mmol litre(-1). Recommended minimal discard volumes are inadequate in the presence of glucose as the flush solution and can lead to high blood glucose readings, inappropriate insulin use, and iatrogenic neuroglycopaenia. Our study demonstrates that the closed-loop arterial sampling system could be the universal solution sought by the NPSA.

  19. Fabrication of a Neotrachea Using Engineered Cartilage

    PubMed Central

    Weidenbecher, Mark; Tucker, Harvey M.; Awadallah, Amad; Dennis, James E.

    2008-01-01

    Objectives Surgical management of long-segment tracheal stenosis is an ongoing problem. Many types of tracheal prostheses have been tried but with limited success because of immune rejection, graft ischemia, or restenosis. Tissue engineered cartilage may offer a solution to this problem, although scaffolds, which are currently often used for support, can lead to biocompatibility problems. This study investigated the feasibility of scaffold-free cartilage to tissue engineer a vascularized neotrachea in rabbits. Study Design Animal study. Methods Autologous neotracheal constructs were implanted in the abdomen of six New Zealand white rabbits. Auricular chondrocytes were used to engineer scaffold-free cartilage sheets. A muscle flap raised from the external abdominal oblique muscle and the engineered cartilage were wrapped around a silicone stent to fabricate a vascularized neotrachea in vivo. In two of the six rabbits, a full thickness skin graft was used to create an epithelial lining. The constructs were harvested after either 6 or 10 weeks. Results All neotracheal constructs were healthy with well-vascularized and integrated layers. The implanted engineered cartilage underwent a remodeling process, forming a solid tracheal framework. Constructs harvested after 10 weeks proved to have significantly better mechanical properties than after 6 weeks and were comparable with the rabbit's native trachea. Conclusion Scaffold-free engineered cartilage can successfully fabricate a well-vascularized, autologous neotrachea with excellent mechanical properties. The results suggest that this approach can be used to reconstruct tracheal defects in rabbits. PMID:18197138

  20. Reconstruction of structure and function in tissue engineering of solid organs: Toward simulation of natural development based on decellularization.

    PubMed

    Zheng, Chen-Xi; Sui, Bing-Dong; Hu, Cheng-Hu; Qiu, Xin-Yu; Zhao, Pan; Jin, Yan

    2018-04-27

    Failure of solid organs, such as the heart, liver, and kidney, remains a major cause of the world's mortality due to critical shortage of donor organs. Tissue engineering, which uses elements including cells, scaffolds, and growth factors to fabricate functional organs in vitro, is a promising strategy to mitigate the scarcity of transplantable organs. Within recent years, different construction strategies that guide the combination of tissue engineering elements have been applied in solid organ tissue engineering and have achieved much progress. Most attractively, construction strategy based on whole-organ decellularization has become a popular and promising approach, because the overall structure of extracellular matrix can be well preserved. However, despite the preservation of whole structure, the current constructs derived from decellularization-based strategy still perform partial functions of solid organs, due to several challenges, including preservation of functional extracellular matrix structure, implementation of functional recellularization, formation of functional vascular network, and realization of long-term functional integration. This review overviews the status quo of solid organ tissue engineering, including both advances and challenges. We have also put forward a few techniques with potential to solve the challenges, mainly focusing on decellularization-based construction strategy. We propose that the primary concept for constructing tissue-engineered solid organs is fabricating functional organs based on intact structure via simulating the natural development and regeneration processes. Copyright © 2018 John Wiley & Sons, Ltd.

  1. Systems engineering management plan : Dallas Integrated Corridor Management (ICM) demonstration project.

    DOT National Transportation Integrated Search

    2010-12-01

    The purpose of the Dallas ICM System is to implement a multi-modal operations decision support tool enabled by real-time data pertaining to the operation of freeways, arterials, and public transit. The system will be shared between information system...

  2. Conditional expression of the type 2 angiotensin II receptor in mesenchymal stem cells inhibits neointimal formation after arterial injury.

    PubMed

    Feng, Jian; Liu, Jian-Ping; Miao, Li; He, Guo-Xiang; Li, De; Wang, Hai-Dong; Jing, Tao

    2014-10-01

    Percutaneous coronary interventions (PCIs) are an effective treatment for obstructive coronary artery diseases. However, the procedure's success is limited by remodeling and formation of neointima. In the present study, we engineered rat mesenchymal stem cells (MSCs) to express type 2 angiotensin II receptor (AT2R) using a tetracycline-regulated system that can strictly regulate AT2R expression. We tested the ability of the modified MSCs to reduce neointima formation following arterial injury. We subjected rats to balloon injury, and reverse transcriptase polymerase chain reaction (RT-PCR) indicated no significant AT2R expression in normal rat arteries. Low expression of AT2R was observed at 28 days after balloon-induced injury. Interestingly, MSCs alone were unable to reduce neointimal hyperplasia after balloon-induced injury; after transplantation of modified MSCs, doxycycline treatment significantly upregulated neointimal AT2R expression and inhibited osteopontin mRNA expression, as well as neointimal formation. Taken together, these results suggest that transplantation of MSCs conditionally expressing AT2R could effectively suppress neointimal hyperplasia following balloon-induced injury. Therefore, MSCs with a doxycycline-controlled gene induction system may be useful for the management of arterial injury after PCI.

  3. Effect of engineered nanoparticles on vasomotor responses in rat intrapulmonary artery

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Courtois, Arnaud, E-mail: arnaud.courtois@u-bordeaux2.f; Inserm, U885, Bordeaux, F-33076; Andujar, Pascal

    2010-06-01

    Pulmonary circulation could be one of the primary vascular targets of finest particles that can deeply penetrate into the lungs after inhalation. We investigated the effects of engineered nanoparticles on vasomotor responses of small intrapulmonary arteries using isometric tension measurements. Acute in vitro exposure to carbon nanoparticles (CNP) decreased, and in some case abolished, the vasomotor responses induced by several vasoactive agents, whereas acute exposure to titanium dioxide nanoparticles (TiO{sub 2}NP) did not. This could be attributed to a decrease in the activity of those vasoactive agents (including PGF{sub 2{alpha}}, serotonin, endothelin-1 and acetylcholine), as suggested when they were exposedmore » to CNP before being applied to arteries. Also, CNP decreased the contraction induced by 30 mM KCl, without decreasing its activity. After endoplasmic reticulum calcium stores depletion (by caffeine and thapsigargin), CaCl{sub 2} addition induced a contraction, dependent on Store-Operated Calcium Channels that was not modified by acute CNP exposure. Further addition of 30 mM KCl elicited a contraction, originating from activation of Voltage-Operated Calcium Channels that was diminished by CNP. Contractile responses to PGF{sub 2{alpha}} or KCl, and relaxation to acetylcholine were modified neither in pulmonary arteries exposed in vitro for prolonged time to CNP or TiO{sub 2}NP, nor in those removed from rats intratracheally instilled with CNP or TiO{sub 2}NP. In conclusion, prolonged in vitro or in vivo exposure to CNP or TiO{sub 2}NP does not affect vasomotor responses of pulmonary arteries. However, acute exposure to CNP decreases contraction mediated by activation of Voltage-Operated, but not Store-Operated, Calcium Channels. Moreover, interaction of some vasoactive agents with CNP decreases their biological activity that might lead to misinterpretation of experimental data.« less

  4. Predicting on-site environmental impacts of municipal engineering works

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Gangolells, Marta, E-mail: marta.gangolells@upc.edu; Casals, Miquel, E-mail: miquel.casals@upc.edu; Forcada, Núria, E-mail: nuria.forcada@upc.edu

    2014-01-15

    The research findings fill a gap in the body of knowledge by presenting an effective way to evaluate the significance of on-site environmental impacts of municipal engineering works prior to the construction stage. First, 42 on-site environmental impacts of municipal engineering works were identified by means of a process-oriented approach. Then, 46 indicators and their corresponding significance limits were determined on the basis of a statistical analysis of 25 new-build and remodelling municipal engineering projects. In order to ensure the objectivity of the assessment process, direct and indirect indicators were always based on quantitative data from the municipal engineering projectmore » documents. Finally, two case studies were analysed and found to illustrate the practical use of the proposed model. The model highlights the significant environmental impacts of a particular municipal engineering project prior to the construction stage. Consequently, preventive actions can be planned and implemented during on-site activities. The results of the model also allow a comparison of proposed municipal engineering projects and alternatives with respect to the overall on-site environmental impact and the absolute importance of a particular environmental aspect. These findings are useful within the framework of the environmental impact assessment process, as they help to improve the identification and evaluation of on-site environmental aspects of municipal engineering works. The findings may also be of use to construction companies that are willing to implement an environmental management system or simply wish to improve on-site environmental performance in municipal engineering projects. -- Highlights: • We present a model to predict the environmental impacts of municipal engineering works. • It highlights significant on-site environmental impacts prior to the construction stage. • Findings are useful within the environmental impact assessment process. • They also help contractors to implement environmental management systems.« less

  5. Mathematical models of real geometrical factors in restricted blood vessels for the analysis of CAD (coronary artery diseases) using Legendre, Boubaker and Bessel polynomials.

    PubMed

    Awojoyogbe, O B; Faromika, O P; Dada, M; Boubaker, Karem; Ojambati, O S

    2011-12-01

    Most cardiovascular emergencies are directly caused by coronary artery disease. Coronary arteries can become clogged or occluded, leading to damage to the heart muscle supplied by the artery. Modem cardiovascular medicine can certainly be improved by meticulous analysis of geometrical factors closely associated with the degenerative disease that results in narrowing of the coronary arteries. There are, however, inherent difficulties in developing this type of mathematical models to completely describe the real or ideal geometries that are very critical in plaque formation and thickening of the vessel wall. Neither the mathematical models of the blood vessels with arthrosclerosis generated by the heart and blood flow or the NMR/MRI data to construct them are available. In this study, a mathematical formulation for the geometrical factors that are very critical for the understanding of coronary artery disease is presented. Based on the Bloch NMR flow equations, we derive analytical expressions to describe in detail the NMR transverse magnetizations and signals as a function of some NMR flow and geometrical parameters which are invaluable for the analysis of blood flow in restricted blood vessels. The procedure would apply to the situations in which the geometry of the fatty deposits, (plague) on the interior walls of the coronary arteries is spherical. The boundary conditions are introduced based on Bessel, Boubaker and Legendre polynomials.

  6. Presentation on systems cluster research

    NASA Technical Reports Server (NTRS)

    Morgenthaler, George W.

    1989-01-01

    This viewgraph presentation presents an overview of systems cluster research performed by the Center for Space Construction. The goals of the research are to develop concepts, insights, and models for space construction and to develop systems engineering/analysis curricula for training future aerospace engineers. The following topics are covered: CSC systems analysis/systems engineering (SIMCON) model, CSC systems cluster schedule, system life-cycle, model optimization techniques, publications, cooperative efforts, and sponsored research.

  7. Novel imaging analysis system to measure the spatial dimension of engineered tissue construct.

    PubMed

    Choi, Kyoung-Hwan; Yoo, Byung-Su; Park, So Ra; Choi, Byung Hyune; Min, Byoung-Hyun

    2010-02-01

    The measurement of the spatial dimensions of tissue-engineered constructs is very important for their clinical applications. In this study, a novel method to measure the volume of tissue-engineered constructs was developed using iterative mathematical computations. The method measures and analyzes three-dimensional (3D) parameters of a construct to estimate its actual volume using a sequence of software-based mathematical algorithms. The mathematical algorithm is composed of two stages: the shape extraction and the determination of volume. The shape extraction utilized 3D images of a construct: length, width, and thickness, captured by a high-quality camera with charge coupled device. The surface of the 3D images was then divided into fine sections. The area of each section was measured and combined to obtain the total surface area. The 3D volume of the target construct was then mathematically obtained using its total surface area and thickness. The accuracy of the measurement method was verified by comparing the results with those obtained from the hydrostatic weighing method (Korea Research Institute of Standards and Science [KRISS], Korea). The mean difference in volume between two methods was 0.0313 +/- 0.0003% (n = 5, P = 0.523) with no significant statistical difference. In conclusion, our image-based spatial measurement system is a reliable and easy method to obtain an accurate 3D volume of a tissue-engineered construct.

  8. Analysis of the Quality of Information Obtained About Uterine Artery Embolization From the Internet

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Tavare, Aniket N.; Alsafi, Ali, E-mail: ali.alsafi03@imperial.ac.uk; Hamady, Mohamad S.

    Purpose: The Internet is widely used by patients to source health care-related information. We sought to analyse the quality of information available on the Internet about uterine artery embolization (UAE). Materials and Methods: We searched three major search engines for the phrase 'uterine artery embolization' and compiled the top 50 results from each engine. After excluding repeated sites, scientific articles, and links to documents, the remaining 50 sites were assessed using the LIDA instrument, which scores sites across the domains of accessibility, usability, and reliability. The Fleisch reading ease score (FRES) was calculated for each of the sites. Finally, wemore » checked the country of origin and the presence of certification by the Health On the Net Foundation (HONcode) as well as their effect on LIDA and FRES scores.ResultsThe following mean scores were obtained: accessibility 48/60 (80%), usability 42/54 (77%), reliability 20/51 (39%), total LIDA 110/165 (67%), and FRES 42/100 (42%). Nine sites had HONcode certification, and this was associated with significantly greater (p < 0.05) reliability and total LIDA and FRES scores. When comparing sites between United Kingdom and United States, there was marked variation in the quality of results obtained when searching for information on UAE (p < 0.05). Conclusion: In general, sites were well designed and easy to use. However, many scored poorly on the reliability of their information either because they were produced in a non-evidence-based way or because they lacking currency. It is important that patients are guided to reputable, location-specific sources of information online, especially because prominent search engine rank does not guarantee reliability of information.« less

  9. Comparison of the Framingham Risk Score, UKPDS Risk Engine, and SCORE for Predicting Carotid Atherosclerosis and Peripheral Arterial Disease in Korean Type 2 Diabetic Patients.

    PubMed

    Ahn, Hye-Ran; Shin, Min-Ho; Yun, Woo-Jun; Kim, Hye-Yeon; Lee, Young-Hoon; Kweon, Sun-Seog; Rhee, Jung-Ae; Choi, Jin-Su; Choi, Seong-Woo

    2011-03-01

    To compare the predictability of the Framingham Risk Score (FRS), United Kingdom Prospective Diabetes Study (UKPDS) risk engine, and the Systematic Coronary Risk Evaluation (SCORE) for carotid atherosclerosis and peripheral arterial disease in Korean type 2 diabetic patients. Among 1,275 registered type 2 diabetes patients in the health center, 621 subjects with type 2 diabetes participated in the study. Well-trained examiners measured the carotid intima-media thickness (IMT), carotid plaque, and ankle brachial index (ABI). The subject's 10-year risk of coronary heart disease was calculated according to the FRS, UKPDS, and SCORE risk scores. These three risk scores were compared to the areas under the curve (AUC). The odds ratios (ORs) of all risk scores increased as the quartiles increased for plaque, IMT, and ABI. For plaque and IMT, the UKPDS risk score provided the highest OR (95% confidence interval) at 3.82 (2.36, 6.17) and at 6.21 (3.37, 11.45). For ABI, the SCORE risk estimation provided the highest OR at 7.41 (3.20, 17.18). However, no significant difference was detected for plaque, IMT, or ABI (P = 0.839, 0.313, and 0.113, respectively) when the AUCs of the three risk scores were compared. When we graphed the Kernel density distribution of these three risk scores, UKPDS had a higher distribution than FRS and SCORE. No significant difference was observed when comparing the predictability of the FRS, UKPDS risk engine, and SCORE risk estimation for carotid atherosclerosis and peripheral arterial disease in Korean type 2 diabetic patients.

  10. Electrospun Polycaprolactone Scaffolds for Small-Diameter Tissue Engineered Blood Vessels

    NASA Astrophysics Data System (ADS)

    Lee, Carol Hsiu-Yueh

    Cardiovascular disease is the leading cause of death in the United States with many patients requiring coronary artery bypass grafting. The current standard is using autografts such as the saphenous vein or intimal mammary artery, however creating a synthetic graft could eliminate this painful and inconvenient procedure. Large diameter grafts have long been established with materials such as DacronRTM and TeflonRTM, however these materials have not proved successful in small-diameter (< 6 mm) grafts where thrombosis and intimal hyperplasia are common in graft failure. With the use of a synthetic biodegradable polymer (polycaprolactone) we utilize our expertise in electrospinning and femtosecond laser ablation to create a novel tri-layered tissue engineered blood vessel containing microchannels. The benefits of creating a tri-layer is to mimic native arteries that contain an endothelium to prevent thrombosis in the inner layer, aligned smooth muscle cells in the middle to control vasodilation and constriction, and a mechanically robust outer layer. The following work evaluates the mechanical properties of such a graft (tensile, fatigue, burst pressure, and suture retention strength), the ability to rapidly align cells in laser ablated microchannels in PCL scaffolds, and the biological integration (co-culture of endothelial and smooth muscle cells) with electrospun PCL scaffolds. The conclusions from this work establish that the electrospun tri-layers provide adequate mechanical strength as a tissue engineered blood vessel, that laser ablated microchannels are able to contain the smooth muscle cells, and that cells are able to adhere to PCL fibers. However, future work includes adjusting microchannel dimensions to properly align smooth muscle cells along with perfect co-cultures of endothelial and smooth muscle cells on the electrospun tri-layer.

  11. NEARING THE END OF CONSTRUCTION ON THE LOX TEST STAND AT MSFC.

    NASA Image and Video Library

    2015-01-08

    AS THE END OF CONSTRUCTION ON TEST STAND 4697, THE LIQUID OXYGEN TANK TEST STAND AT MARSHALL SPACE FLIGHT CENTER, PROJECT ENGINEERS PHIL HENDRIX, FROM MSFC, AND CURTNEY WALTERS FROM THE U.S. CORP OF ENGINEERS, STUDY PLANS AND PROGRESS.

  12. 23 CFR 660.117 - Funding, records and accounting.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... Highways FEDERAL HIGHWAY ADMINISTRATION, DEPARTMENT OF TRANSPORTATION ENGINEERING AND TRAFFIC OPERATIONS... be required. (b) Funds for FHs may be used for: (1) Planning; (2) Federal Lands Highway research; (3) Preliminary and construction engineering; and (4) Construction. (c) Funds for FHs may be made available for...

  13. Induction of functional tissue-engineered skeletal muscle constructs by defined electrical stimulation.

    PubMed

    Ito, Akira; Yamamoto, Yasunori; Sato, Masanori; Ikeda, Kazushi; Yamamoto, Masahiro; Fujita, Hideaki; Nagamori, Eiji; Kawabe, Yoshinori; Kamihira, Masamichi

    2014-04-24

    Electrical impulses are necessary for proper in vivo skeletal muscle development. To fabricate functional skeletal muscle tissues in vitro, recapitulation of the in vivo niche, including physical stimuli, is crucial. Here, we report a technique to engineer skeletal muscle tissues in vitro by electrical pulse stimulation (EPS). Electrically excitable tissue-engineered skeletal muscle constructs were stimulated with continuous electrical pulses of 0.3 V/mm amplitude, 4 ms width, and 1 Hz frequency, resulting in a 4.5-fold increase in force at day 14. In myogenic differentiation culture, the percentage of peak twitch force (%Pt) was determined as the load on the tissue constructs during the artificial exercise induced by continuous EPS. We optimized the stimulation protocol, wherein the tissues were first subjected to 24.5%Pt, which was increased to 50-60%Pt as the tissues developed. This technique may be a useful approach to fabricate tissue-engineered functional skeletal muscle constructs.

  14. Plant nitrogen regulatory P-PII polypeptides

    DOEpatents

    Coruzzi, Gloria M.; Lam, Hon-Ming; Hsieh, Ming-Hsiun

    2004-11-23

    The present invention generally relates to plant nitrogen regulatory PII gene (hereinafter P-PII gene), a gene involved in regulating plant nitrogen metabolism. The invention provides P-PII nucleotide sequences, expression constructs comprising said nucleotide sequences, and host cells and plants having said constructs and, optionally expressing the P-PII gene from said constructs. The invention also provides substantially pure P-PII proteins. The P-PII nucleotide sequences and constructs of the invention may be used to engineer organisms to overexpress wild-type or mutant P-PII regulatory protein. Engineered plants that overexpress or underexpress P-PII regulatory protein may have increased nitrogen assimilation capacity. Engineered organisms may be used to produce P-PII proteins which, in turn, can be used for a variety of purposes including in vitro screening of herbicides. P-PII nucleotide sequences have additional uses as probes for isolating additional genomic clones having the promoters of P-PII gene. P-PII promoters are light- and/or sucrose-inducible and may be advantageously used in genetic engineering of plants.

  15. 48 CFR 1536.602 - Selection of firms for architect-engineer contracts.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... architect-engineer contracts. 1536.602 Section 1536.602 Federal Acquisition Regulations System ENVIRONMENTAL PROTECTION AGENCY SPECIAL CATEGORIES OF CONTRACTING CONSTRUCTION AND ARCHITECT-ENGINEER CONTRACTS Architect-Engineer Services 1536.602 Selection of firms for architect-engineer contracts. ...

  16. 48 CFR 636.602 - Selection of firms for architect-engineer contracts.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... architect-engineer contracts. 636.602 Section 636.602 Federal Acquisition Regulations System DEPARTMENT OF STATE SPECIAL CATEGORIES OF CONTRACTING CONSTRUCTION AND ARCHITECT-ENGINEER CONTRACTS Architect-Engineer Services 636.602 Selection of firms for architect-engineer contracts. ...

  17. 48 CFR 1536.602 - Selection of firms for architect-engineer contracts.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... architect-engineer contracts. 1536.602 Section 1536.602 Federal Acquisition Regulations System ENVIRONMENTAL PROTECTION AGENCY SPECIAL CATEGORIES OF CONTRACTING CONSTRUCTION AND ARCHITECT-ENGINEER CONTRACTS Architect-Engineer Services 1536.602 Selection of firms for architect-engineer contracts. ...

  18. 48 CFR 2936.602 - Selection of firms for architect-engineer contracts.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... architect-engineer contracts. 2936.602 Section 2936.602 Federal Acquisition Regulations System DEPARTMENT OF LABOR GENERAL CONTRACTING REQUIREMENTS CONSTRUCTION AND ARCHITECT-ENGINEER CONTRACTS Architect-Engineer Services 2936.602 Selection of firms for architect-engineer contracts. ...

  19. 48 CFR 436.602 - Selection of firms for architect-engineer contracts.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... architect-engineer contracts. 436.602 Section 436.602 Federal Acquisition Regulations System DEPARTMENT OF AGRICULTURE SPECIAL CATEGORIES OF CONTRACTING CONSTRUCTION AND ARCHITECT-ENGINEER CONTRACTS Architect-Engineer Service 436.602 Selection of firms for architect-engineer contracts. ...

  20. 48 CFR 1336.602 - Selection of firms for architect-engineer contracts.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... architect-engineer contracts. 1336.602 Section 1336.602 Federal Acquisition Regulations System DEPARTMENT OF COMMERCE SPECIAL CATEGORIES OF CONTRACTING CONSTRUCTION AND ARCHITECT-ENGINEER CONTRACTS Architect-Engineer Services 1336.602 Selection of firms for architect-engineer contracts. ...

  1. 48 CFR 636.602 - Selection of firms for architect-engineer contracts.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... architect-engineer contracts. 636.602 Section 636.602 Federal Acquisition Regulations System DEPARTMENT OF STATE SPECIAL CATEGORIES OF CONTRACTING CONSTRUCTION AND ARCHITECT-ENGINEER CONTRACTS Architect-Engineer Services 636.602 Selection of firms for architect-engineer contracts. ...

  2. 48 CFR 536.602 - Selection of firms for architect-engineer contracts.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... architect-engineer contracts. 536.602 Section 536.602 Federal Acquisition Regulations System GENERAL SERVICES ADMINISTRATION SPECIAL CATEGORIES OF CONTRACTING CONSTRUCTION AND ARCHITECT-ENGINEER CONTRACTS Architect-Engineer Services 536.602 Selection of firms for architect-engineer contracts. ...

  3. 48 CFR 36.602 - Selection of firms for architect-engineer contracts.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... architect-engineer contracts. 36.602 Section 36.602 Federal Acquisition Regulations System FEDERAL ACQUISITION REGULATION SPECIAL CATEGORIES OF CONTRACTING CONSTRUCTION AND ARCHITECT-ENGINEER CONTRACTS Architect-Engineer Services 36.602 Selection of firms for architect-engineer contracts. ...

  4. 48 CFR 536.602 - Selection of firms for architect-engineer contracts.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... architect-engineer contracts. 536.602 Section 536.602 Federal Acquisition Regulations System GENERAL SERVICES ADMINISTRATION SPECIAL CATEGORIES OF CONTRACTING CONSTRUCTION AND ARCHITECT-ENGINEER CONTRACTS Architect-Engineer Services 536.602 Selection of firms for architect-engineer contracts. ...

  5. 48 CFR 636.602 - Selection of firms for architect-engineer contracts.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... architect-engineer contracts. 636.602 Section 636.602 Federal Acquisition Regulations System DEPARTMENT OF STATE SPECIAL CATEGORIES OF CONTRACTING CONSTRUCTION AND ARCHITECT-ENGINEER CONTRACTS Architect-Engineer Services 636.602 Selection of firms for architect-engineer contracts. ...

  6. 48 CFR 36.602 - Selection of firms for architect-engineer contracts.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... architect-engineer contracts. 36.602 Section 36.602 Federal Acquisition Regulations System FEDERAL ACQUISITION REGULATION SPECIAL CATEGORIES OF CONTRACTING CONSTRUCTION AND ARCHITECT-ENGINEER CONTRACTS Architect-Engineer Services 36.602 Selection of firms for architect-engineer contracts. ...

  7. 48 CFR 2936.602 - Selection of firms for architect-engineer contracts.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... architect-engineer contracts. 2936.602 Section 2936.602 Federal Acquisition Regulations System DEPARTMENT OF LABOR GENERAL CONTRACTING REQUIREMENTS CONSTRUCTION AND ARCHITECT-ENGINEER CONTRACTS Architect-Engineer Services 2936.602 Selection of firms for architect-engineer contracts. ...

  8. 48 CFR 36.602 - Selection of firms for architect-engineer contracts.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... architect-engineer contracts. 36.602 Section 36.602 Federal Acquisition Regulations System FEDERAL ACQUISITION REGULATION SPECIAL CATEGORIES OF CONTRACTING CONSTRUCTION AND ARCHITECT-ENGINEER CONTRACTS Architect-Engineer Services 36.602 Selection of firms for architect-engineer contracts. ...

  9. 48 CFR 36.602 - Selection of firms for architect-engineer contracts.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... architect-engineer contracts. 36.602 Section 36.602 Federal Acquisition Regulations System FEDERAL ACQUISITION REGULATION SPECIAL CATEGORIES OF CONTRACTING CONSTRUCTION AND ARCHITECT-ENGINEER CONTRACTS Architect-Engineer Services 36.602 Selection of firms for architect-engineer contracts. ...

  10. 48 CFR 1536.602 - Selection of firms for architect-engineer contracts.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... architect-engineer contracts. 1536.602 Section 1536.602 Federal Acquisition Regulations System ENVIRONMENTAL PROTECTION AGENCY SPECIAL CATEGORIES OF CONTRACTING CONSTRUCTION AND ARCHITECT-ENGINEER CONTRACTS Architect-Engineer Services 1536.602 Selection of firms for architect-engineer contracts. ...

  11. 48 CFR 2936.602 - Selection of firms for architect-engineer contracts.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... architect-engineer contracts. 2936.602 Section 2936.602 Federal Acquisition Regulations System DEPARTMENT OF LABOR GENERAL CONTRACTING REQUIREMENTS CONSTRUCTION AND ARCHITECT-ENGINEER CONTRACTS Architect-Engineer Services 2936.602 Selection of firms for architect-engineer contracts. ...

  12. 48 CFR 536.602 - Selection of firms for architect-engineer contracts.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... architect-engineer contracts. 536.602 Section 536.602 Federal Acquisition Regulations System GENERAL SERVICES ADMINISTRATION SPECIAL CATEGORIES OF CONTRACTING CONSTRUCTION AND ARCHITECT-ENGINEER CONTRACTS Architect-Engineer Services 536.602 Selection of firms for architect-engineer contracts. ...

  13. 48 CFR 1336.602 - Selection of firms for architect-engineer contracts.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... architect-engineer contracts. 1336.602 Section 1336.602 Federal Acquisition Regulations System DEPARTMENT OF COMMERCE SPECIAL CATEGORIES OF CONTRACTING CONSTRUCTION AND ARCHITECT-ENGINEER CONTRACTS Architect-Engineer Services 1336.602 Selection of firms for architect-engineer contracts. ...

  14. 48 CFR 436.602 - Selection of firms for architect-engineer contracts.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... architect-engineer contracts. 436.602 Section 436.602 Federal Acquisition Regulations System DEPARTMENT OF AGRICULTURE SPECIAL CATEGORIES OF CONTRACTING CONSTRUCTION AND ARCHITECT-ENGINEER CONTRACTS Architect-Engineer Service 436.602 Selection of firms for architect-engineer contracts. ...

  15. 48 CFR 536.602 - Selection of firms for architect-engineer contracts.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... architect-engineer contracts. 536.602 Section 536.602 Federal Acquisition Regulations System GENERAL SERVICES ADMINISTRATION SPECIAL CATEGORIES OF CONTRACTING CONSTRUCTION AND ARCHITECT-ENGINEER CONTRACTS Architect-Engineer Services 536.602 Selection of firms for architect-engineer contracts. ...

  16. 48 CFR 2936.602 - Selection of firms for architect-engineer contracts.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... architect-engineer contracts. 2936.602 Section 2936.602 Federal Acquisition Regulations System DEPARTMENT OF LABOR GENERAL CONTRACTING REQUIREMENTS CONSTRUCTION AND ARCHITECT-ENGINEER CONTRACTS Architect-Engineer Services 2936.602 Selection of firms for architect-engineer contracts. ...

  17. 48 CFR 36.602 - Selection of firms for architect-engineer contracts.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... architect-engineer contracts. 36.602 Section 36.602 Federal Acquisition Regulations System FEDERAL ACQUISITION REGULATION SPECIAL CATEGORIES OF CONTRACTING CONSTRUCTION AND ARCHITECT-ENGINEER CONTRACTS Architect-Engineer Services 36.602 Selection of firms for architect-engineer contracts. ...

  18. 48 CFR 436.602 - Selection of firms for architect-engineer contracts.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... architect-engineer contracts. 436.602 Section 436.602 Federal Acquisition Regulations System DEPARTMENT OF AGRICULTURE SPECIAL CATEGORIES OF CONTRACTING CONSTRUCTION AND ARCHITECT-ENGINEER CONTRACTS Architect-Engineer Service 436.602 Selection of firms for architect-engineer contracts. ...

  19. 48 CFR 1336.602 - Selection of firms for architect-engineer contracts.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... architect-engineer contracts. 1336.602 Section 1336.602 Federal Acquisition Regulations System DEPARTMENT OF COMMERCE SPECIAL CATEGORIES OF CONTRACTING CONSTRUCTION AND ARCHITECT-ENGINEER CONTRACTS Architect-Engineer Services 1336.602 Selection of firms for architect-engineer contracts. ...

  20. 48 CFR 1536.602 - Selection of firms for architect-engineer contracts.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... architect-engineer contracts. 1536.602 Section 1536.602 Federal Acquisition Regulations System ENVIRONMENTAL PROTECTION AGENCY SPECIAL CATEGORIES OF CONTRACTING CONSTRUCTION AND ARCHITECT-ENGINEER CONTRACTS Architect-Engineer Services 1536.602 Selection of firms for architect-engineer contracts. ...

  1. 48 CFR 2936.602 - Selection of firms for architect-engineer contracts.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... architect-engineer contracts. 2936.602 Section 2936.602 Federal Acquisition Regulations System DEPARTMENT OF LABOR GENERAL CONTRACTING REQUIREMENTS CONSTRUCTION AND ARCHITECT-ENGINEER CONTRACTS Architect-Engineer Services 2936.602 Selection of firms for architect-engineer contracts. ...

  2. 48 CFR 636.602 - Selection of firms for architect-engineer contracts.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... architect-engineer contracts. 636.602 Section 636.602 Federal Acquisition Regulations System DEPARTMENT OF STATE SPECIAL CATEGORIES OF CONTRACTING CONSTRUCTION AND ARCHITECT-ENGINEER CONTRACTS Architect-Engineer Services 636.602 Selection of firms for architect-engineer contracts. ...

  3. 48 CFR 436.602 - Selection of firms for architect-engineer contracts.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... architect-engineer contracts. 436.602 Section 436.602 Federal Acquisition Regulations System DEPARTMENT OF AGRICULTURE SPECIAL CATEGORIES OF CONTRACTING CONSTRUCTION AND ARCHITECT-ENGINEER CONTRACTS Architect-Engineer Service 436.602 Selection of firms for architect-engineer contracts. ...

  4. 48 CFR 1536.602 - Selection of firms for architect-engineer contracts.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... architect-engineer contracts. 1536.602 Section 1536.602 Federal Acquisition Regulations System ENVIRONMENTAL PROTECTION AGENCY SPECIAL CATEGORIES OF CONTRACTING CONSTRUCTION AND ARCHITECT-ENGINEER CONTRACTS Architect-Engineer Services 1536.602 Selection of firms for architect-engineer contracts. ...

  5. 48 CFR 1336.602 - Selection of firms for architect-engineer contracts.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... architect-engineer contracts. 1336.602 Section 1336.602 Federal Acquisition Regulations System DEPARTMENT OF COMMERCE SPECIAL CATEGORIES OF CONTRACTING CONSTRUCTION AND ARCHITECT-ENGINEER CONTRACTS Architect-Engineer Services 1336.602 Selection of firms for architect-engineer contracts. ...

  6. 48 CFR 436.602 - Selection of firms for architect-engineer contracts.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... architect-engineer contracts. 436.602 Section 436.602 Federal Acquisition Regulations System DEPARTMENT OF AGRICULTURE SPECIAL CATEGORIES OF CONTRACTING CONSTRUCTION AND ARCHITECT-ENGINEER CONTRACTS Architect-Engineer Service 436.602 Selection of firms for architect-engineer contracts. ...

  7. 48 CFR 1336.602 - Selection of firms for architect-engineer contracts.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... architect-engineer contracts. 1336.602 Section 1336.602 Federal Acquisition Regulations System DEPARTMENT OF COMMERCE SPECIAL CATEGORIES OF CONTRACTING CONSTRUCTION AND ARCHITECT-ENGINEER CONTRACTS Architect-Engineer Services 1336.602 Selection of firms for architect-engineer contracts. ...

  8. 48 CFR 536.602 - Selection of firms for architect-engineer contracts.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... architect-engineer contracts. 536.602 Section 536.602 Federal Acquisition Regulations System GENERAL SERVICES ADMINISTRATION SPECIAL CATEGORIES OF CONTRACTING CONSTRUCTION AND ARCHITECT-ENGINEER CONTRACTS Architect-Engineer Services 536.602 Selection of firms for architect-engineer contracts. ...

  9. 48 CFR 636.602 - Selection of firms for architect-engineer contracts.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... architect-engineer contracts. 636.602 Section 636.602 Federal Acquisition Regulations System DEPARTMENT OF STATE SPECIAL CATEGORIES OF CONTRACTING CONSTRUCTION AND ARCHITECT-ENGINEER CONTRACTS Architect-Engineer Services 636.602 Selection of firms for architect-engineer contracts. ...

  10. Engineering Microvascularized 3D Tissue Using Alginate-Chitosan Microcapsules.

    PubMed

    Zhang, Wujie; Choi, Jung K; He, Xiaoming

    2017-02-01

    Construction of vascularized tissues is one of the major challenges of tissue engineering. The goal of this study was to engineer 3D microvascular tissues by incorporating the HUVEC-CS cells with a collagen/alginate-chitosan (AC) microcapsule scaffold. In the presence of AC microcapsules, a 3D vascular-like network was clearly observable. The results indicated the importance of AC microcapsules in engineering microvascular tissues -- providing support and guiding alignment of HUVEC-CS cells. This approach provides an alternative and promising method for constructing vascularized tissues.

  11. Details of the Construction and Production of Fuel Pumps and Fuel Nozzles for the Airplane Diesel Engine

    NASA Technical Reports Server (NTRS)

    Lubenetsky, W S

    1936-01-01

    This report presents investigations into the design and construction of fuel pumps for diesel engines. The results of the pump tests on the engines showed that, with a good cut-off, accurate injection, assured by the proper adjustment of the pump elements, there is a decrease in the consumption of fuel and hence an increase in the rated power of the engine. Some of the aspects investigated include: cam profile, coefficient of discharge, and characteristics of the injection system.

  12. Hydrogel Bioprinted Microchannel Networks for Vascularization of Tissue Engineering Constructs

    PubMed Central

    Bertassoni, Luiz E.; Cecconi, Martina; Manoharan, Vijayan; Nikkhah, Mehdi; Hjortnaes, Jesper; Cristino, Ana Luiza; Barabaschi, Giada; Demarchi, Danilo; Dokmeci, Mehmet R.; Yang, Yunzhi; Khademhosseini, Ali

    2014-01-01

    Vascularization remains a critical challenge in tissue engineering. The development of vascular networks within densely populated and metabolically functional tissues facilitate transport of nutrients and removal of waste products, thus preserving cellular viability over a long period of time. Despite tremendous progress in fabricating complex tissue constructs in the past few years, approaches for controlled vascularization within hydrogel based engineered tissue constructs have remained limited. Here, we report a three dimensional (3D) micromolding technique utilizing bioprinted agarose template fibers to fabricate microchannel networks with various architectural features within photo cross linkable hydrogel constructs. Using the proposed approach, we were able to successfully embed functional and perfusable microchannels inside methacrylated gelatin (GelMA), star poly (ethylene glycol-co-lactide) acrylate (SPELA), poly (ethylene glycol) dimethacrylate (PEGDMA) and poly (ethylene glycol) diacrylate (PEGDA) hydrogels at different concentrations. In particular, GelMA hydrogels were used as a model to demonstrate the functionality of the fabricated vascular networks in improving mass transport, cellular viability and differentiation within the cell-laden tissue constructs. In addition, successful formation of endothelial monolayers within the fabricated channels was confirmed. Overall, our proposed strategy represents an effective technique for vascularization of hydrogel constructs with useful applications in tissue engineering and organs on a chip. PMID:24860845

  13. APPLICATION OF THE 3D MODEL OF RAILWAY VIADUCTS TO COST ESTIMATION AND CONSTRUCTION

    NASA Astrophysics Data System (ADS)

    Fujisawa, Yasuo; Yabuki, Nobuyoshi; Igarashi, Zenichi; Yoshino, Hiroyuki

    Three dimensional models of civil engineering structures are only partially used in either design or construction but not both. Research on integration of design, cost estimation and construction by 3Dmodels has not been heard in civil engineering domain yet. Using continuously a 3D product model of a structure from design to construction through estimation should improve the efficiency and decrease the occurrence of mistakes, hence enhancing the quality. In this research, we investigated the current practices of flow from design to construction, particularly focusing on cost estimation. Then, we identified advantages and issues on utilization of 3D design models to estimation and construction by applying 3D models to an actual railway construction project.

  14. Industrial Education. "Small Engines".

    ERIC Educational Resources Information Center

    Parma City School District, OH.

    Part of a series of curriculum guides dealing with industrial education in junior high schools, this guide provides the student with information and manipulative experiences on small gasoline engines. Included are sections on shop adjustment, safety, small engines, internal combustion, engine construction, four stroke engines, two stroke engines,…

  15. Morphological Features of the Porcine Lacrimal Gland and Its Compatibility for Human Lacrimal Gland Xenografting

    PubMed Central

    Gaffling, Simone; Asano, Nagayoshi; Hampel, Ulrike; Garreis, Fabian; Hornegger, Joachim; Paulsen, Friedrich

    2013-01-01

    In this study, we present first data concerning the anatomical structure, blood supply and location of the lacrimal gland of the pig. Our data indicate that the porcine lacrimal gland may serve as a potential xenograft candidate in humans or as an animal model for engineering of a bioartificial lacrimal gland tissue construct for clinical application. For this purpose, we used different macroscopic preparation techniques and digital reconstruction of the histological gland morphology to gain new insights and important information concerning the feasibility of a lacrimal gland transplantation from pig to humans in general. Our results show that the lacrimal gland of the pig reveals a lot of morphological similarities to the analogous human lacrimal gland and thus might be regarded as a xenograft in the future. This is true for a similar anatomical location within the orbit as well as for the feeding artery supply to the organ. Functional differences concerning the composition of the tear fluid, due to a different secretory unit distribution within the gland tissue will, however, be a challenge in future investigations. PMID:24069265

  16. Morphological features of the porcine lacrimal gland and its compatibility for human lacrimal gland xenografting.

    PubMed

    Henker, Robert; Scholz, Michael; Gaffling, Simone; Asano, Nagayoshi; Hampel, Ulrike; Garreis, Fabian; Hornegger, Joachim; Paulsen, Friedrich

    2013-01-01

    In this study, we present first data concerning the anatomical structure, blood supply and location of the lacrimal gland of the pig. Our data indicate that the porcine lacrimal gland may serve as a potential xenograft candidate in humans or as an animal model for engineering of a bioartificial lacrimal gland tissue construct for clinical application. For this purpose, we used different macroscopic preparation techniques and digital reconstruction of the histological gland morphology to gain new insights and important information concerning the feasibility of a lacrimal gland transplantation from pig to humans in general. Our results show that the lacrimal gland of the pig reveals a lot of morphological similarities to the analogous human lacrimal gland and thus might be regarded as a xenograft in the future. This is true for a similar anatomical location within the orbit as well as for the feeding artery supply to the organ. Functional differences concerning the composition of the tear fluid, due to a different secretory unit distribution within the gland tissue will, however, be a challenge in future investigations.

  17. Growth Factor Stimulation Improves the Structure and Properties of Scaffold-Free Engineered Auricular Cartilage Constructs

    PubMed Central

    Rosa, Renata G.; Joazeiro, Paulo P.; Bianco, Juares; Kunz, Manuela; Weber, Joanna F.; Waldman, Stephen D.

    2014-01-01

    The reconstruction of the external ear to correct congenital deformities or repair following trauma remains a significant challenge in reconstructive surgery. Previously, we have developed a novel approach to create scaffold-free, tissue engineering elastic cartilage constructs directly from a small population of donor cells. Although the developed constructs appeared to adopt the structural appearance of native auricular cartilage, the constructs displayed limited expression and poor localization of elastin. In the present study, the effect of growth factor supplementation (insulin, IGF-1, or TGF-β1) was investigated to stimulate elastogenesis as well as to improve overall tissue formation. Using rabbit auricular chondrocytes, bioreactor-cultivated constructs supplemented with either insulin or IGF-1 displayed increased deposition of cartilaginous ECM, improved mechanical properties, and thicknesses comparable to native auricular cartilage after 4 weeks of growth. Similarly, growth factor supplementation resulted in increased expression and improved localization of elastin, primarily restricted within the cartilaginous region of the tissue construct. Additional studies were conducted to determine whether scaffold-free engineered auricular cartilage constructs could be developed in the 3D shape of the external ear. Isolated auricular chondrocytes were grown in rapid-prototyped tissue culture molds with additional insulin or IGF-1 supplementation during bioreactor cultivation. Using this approach, the developed tissue constructs were flexible and had a 3D shape in very good agreement to the culture mold (average error <400 µm). While scaffold-free, engineered auricular cartilage constructs can be created with both the appropriate tissue structure and 3D shape of the external ear, future studies will be aimed assessing potential changes in construct shape and properties after subcutaneous implantation. PMID:25126941

  18. Conceptional Considerations to Energy Balance and Global Warming Potential of Soil Bioengineering Structures

    NASA Astrophysics Data System (ADS)

    von der Thannen, Magdalena; Paratscha, Roman; Smutny, Roman; Lampalzer, Thomas; Strauss, Alfred; Rauch, Hans Peter

    2016-04-01

    Nowadays there is a high demand on engineering solutions considering not only technical aspects but also ecological and aesthetic values. In this context soil bioengineering techniques are often used as standalone solutions or in combination with conventional engineering structures. It is a construction technique that uses biological components for hydraulic and civil engineering solutions. In general it pursues the same objectives as conventional civil engineering structures. Currently the used assessment methods for soil bioengineering structures are referencing technically, ecologically and socio-economically. In a modern engineering approach additionally, environmental impacts and potential added values should be considered. The research project E-Protect aims at developing Environmental Life Cycle Assessment (LCA) models for this special field of alpine protective constructions. Both, the Cumulative Energy Demand (CED) and the Global Warming Potential (GWP) should be considered in an Environmental LCA over the whole life cycle of an engineering structure. The life cycle itself can be divided into three phases: the construction phase, the use phase and the end of life phase. The paper represents a concept to apply an Environmental LCA model for soil bioengineering structures. Beside the construction phase of these structures particular attention will be given to the use phase. It is not only important in terms of engineering effects but also plays an important role for positive carbon footprint due to the growing plants of soil bioengineering structures in contrast to conventional structures. Innovative Environmental LCA models will be applied to soil bioengineering structures which provide a new transparency for the responsible planners and stakeholders, by pointing out the total consumption of resources in all construction phases and components.

  19. Patient-specific system for prognosis of surgical treatment outcomes of human cardiovascular system

    NASA Astrophysics Data System (ADS)

    Golyadkina, Anastasiya A.; Kalinin, Aleksey A.; Kirillova, Irina V.; Kossovich, Elena L.; Kossovich, Leonid Y.; Menishova, Liyana R.; Polienko, Asel V.

    2015-03-01

    Object of study: Improvement of life quality of patients with high stroke risk ia the main goal for development of system for patient-specific modeling of cardiovascular system. This work is dedicated at increase of safety outcomes for surgical treatment of brain blood supply alterations. The objects of study are common carotid artery, internal and external carotid arteries and bulb. Methods: We estimated mechanical properties of carotid arteries tissues and patching materials utilized at angioplasty. We studied angioarchitecture features of arteries. We developed and clinically adapted computer biomechanical models, which are characterized by geometrical, physical and mechanical similarity with carotid artery in norm and with pathology (atherosclerosis, pathological tortuosity, and their combination). Results: Collaboration of practicing cardiovascular surgeons and specialists in the area of Mathematics and Mechanics allowed to successfully conduct finite-element modeling of surgical treatment taking into account various features of operation techniques and patching materials for a specific patient. Numerical experiment allowed to reveal factors leading to brain blood supply decrease and atherosclerosis development. Modeling of carotid artery reconstruction surgery for a specific patient on the basis of the constructed biomechanical model demonstrated the possibility of its application in clinical practice at approximation of numerical experiment to the real conditions.

  20. Possibility of reducing CO2 emissions from internal combustion engines

    NASA Astrophysics Data System (ADS)

    Drabik, Dawid; Mamala, Jarosław; Śmieja, Michał; Prażnowski, Krzysztof

    2017-10-01

    Article defines on the possibility of reduction CO2 of the internal combustion engine and presents the analysis based on originally conducted studies. The increase in overall engine efficiency is sought after by all engineers dealing with engine construction, one of the major ways to reduce CO2 emissions is to increase the compression ratio. The application of the compression ratio that has been increased constructional in the engine will, on one hand, bring about the increase in the theoretical efficiency, but, on the other hand, require a system for pressure control at a higher engine load in order to prevent engine knocking. For the purposes of the article there was carried out a number of studies and compiled results, and on their basis determined what have a major impact on the reducing CO2.

  1. Design type air engine Di Pietro

    NASA Astrophysics Data System (ADS)

    Zwierzchowski, Jaroslaw

    The article presents a pneumatic engine constructed by Angelo Di Pietro. 3D solid models of pneumatic engine components were presented therein. A directional valve is a key element of the control system. The valve functions as a camshaft distributing air to particular engine chambers. The construction designed by Angelo Di Pietro is modern and innovative. A pneumatic engine requires low pressure to start rotary movement. With the use of CFD software, the fields of velocity vectors' distribution were determined. Moreover, the author determined the distribution of pressure values in engine inlet and outlet channels. CFD model studies on engine operation were conducted for chosen stages of operating cycles. On the basis of simulation tests that were conducted, the values of flow rates for the engine were determined. The distribution of pressure values made it possible to evaluate the torque value on the rotating shaft.

  2. On civil engineering disasters and their mitigation

    NASA Astrophysics Data System (ADS)

    Xie, Lili; Qu, Zhe

    2018-01-01

    Civil engineering works such as buildings and infrastructure are the carriers of human civilization. They are, however, also the origins of various types of disasters, which are referred to in this paper as civil engineering disasters. This paper presents the concept of civil engineering disasters, their characteristics, classification, causes, and mitigation technologies. Civil engineering disasters are caused primarily by civil engineering defects, which are usually attributed to improper selection of construction site, hazard assessment, design and construction, occupancy, and maintenance. From this viewpoint, many so-called natural disasters such as earthquakes, strong winds, floods, landslides, and debris flows are substantially due to civil engineering defects rather than the actual natural hazards. Civil engineering disasters occur frequently and globally and are the most closely related to human beings among all disasters. This paper emphasizes that such disasters can be mitigated mainly through civil engineering measures, and outlines the related objectives and scientific and technological challenges.

  3. A Computational Model for Biomechanical Effects of Arterial Compliance Mismatch

    PubMed Central

    He, Fan; Hua, Lu; Gao, Li-jian

    2015-01-01

    Background. Compliance mismatch is a negative factor and it needs to be considered in arterial bypass grafting. Objective. A computational model was employed to investigate the effects of arterial compliance mismatch on blood flow, wall stress, and deformation. Methods. The unsteady blood flow was assumed to be laminar, Newtonian, viscous, and incompressible. The vessel wall was assumed to be linear elastic, isotropic, and incompressible. The fluid-wall interaction scheme was constructed using the finite element method. Results. The results show that there are identical wall shear stress waveforms, wall stress, and strain waveforms at different locations. The comparison of the results demonstrates that wall shear stresses and wall strains are higher while wall stresses are lower at the more compliant section. The differences promote the probability of intimal thickening at some locations. Conclusions. The model is effective and gives satisfactory results. It could be extended to all kinds of arteries with complicated geometrical and material factors. PMID:27019580

  4. GPU-accelerated Lattice Boltzmann method for anatomical extraction in patient-specific computational hemodynamics

    NASA Astrophysics Data System (ADS)

    Yu, H.; Wang, Z.; Zhang, C.; Chen, N.; Zhao, Y.; Sawchuk, A. P.; Dalsing, M. C.; Teague, S. D.; Cheng, Y.

    2014-11-01

    Existing research of patient-specific computational hemodynamics (PSCH) heavily relies on software for anatomical extraction of blood arteries. Data reconstruction and mesh generation have to be done using existing commercial software due to the gap between medical image processing and CFD, which increases computation burden and introduces inaccuracy during data transformation thus limits the medical applications of PSCH. We use lattice Boltzmann method (LBM) to solve the level-set equation over an Eulerian distance field and implicitly and dynamically segment the artery surfaces from radiological CT/MRI imaging data. The segments seamlessly feed to the LBM based CFD computation of PSCH thus explicit mesh construction and extra data management are avoided. The LBM is ideally suited for GPU (graphic processing unit)-based parallel computing. The parallel acceleration over GPU achieves excellent performance in PSCH computation. An application study will be presented which segments an aortic artery from a chest CT dataset and models PSCH of the segmented artery.

  5. Evaluation of a Novel Laser-assisted Coronary Anastomotic Connector - the Trinity Clip - in a Porcine Off-pump Bypass Model

    PubMed Central

    Stecher, David; Bronkers, Glenn; Noest, Jappe O.T.; Tulleken, Cornelis A.F.; Hoefer, Imo E.; van Herwerden, Lex A.; Pasterkamp, Gerard; Buijsrogge, Marc P.

    2014-01-01

    To simplify and facilitate beating heart (i.e., off-pump), minimally invasive coronary artery bypass surgery, a new coronary anastomotic connector, the Trinity Clip, is developed based on the excimer laser-assisted nonocclusive anastomosis technique. The Trinity Clip connector enables simplified, sutureless, and nonocclusive connection of the graft to the coronary artery, and an excimer laser catheter laser-punches the opening of the anastomosis. Consequently, owing to the complete nonocclusive anastomosis construction, coronary conditioning (i.e., occluding or shunting) is not necessary, in contrast to the conventional anastomotic technique, hence simplifying the off-pump bypass procedure. Prior to clinical application in coronary artery bypass grafting, the safety and quality of this novel connector will be evaluated in a long-term experimental porcine off-pump coronary artery bypass (OPCAB) study. In this paper, we describe how to evaluate the coronary anastomosis in the porcine OPCAB model using various techniques to assess its quality. Representative results are summarized and visually demonstrated. PMID:25490000

  6. Review of sign overlay procedures in Virginia.

    DOT National Transportation Integrated Search

    1984-01-01

    Maintaining the large number of signs on the state's roads demands a substantial effort, especially now that many of the signs erected during construction of the interstate and urban arterial systems are deteriorating to the point of requiring replac...

  7. Practicing Engineering While Building with Blocks: Identifying Engineering Thinking

    ERIC Educational Resources Information Center

    Bagiati, Aikaterini; Evangelou, Demetra

    2016-01-01

    Children's free play naturally enhances skills of observation, communication, experimentation, as well as development of rationale and construction skills. These domains, while synthesised, can lead to the development of certain process models regarding the way constructions could be designed, built and improved. The Design Process model…

  8. Try This: Construct a Water Catchment

    ERIC Educational Resources Information Center

    Teaching Science, 2017

    2017-01-01

    EngQuest, an initiative of Engineers Australia, provides an exciting, non-competitive way for students to participate in free, fun and educational engineering activities involving mathematics, science and technology. This article describes a project designed to teach middle school students how to construct a water catchment system. Water…

  9. 14 CFR 33.34 - Turbocharger rotors.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 14 Aeronautics and Space 1 2010-01-01 2010-01-01 false Turbocharger rotors. 33.34 Section 33.34... STANDARDS: AIRCRAFT ENGINES Design and Construction; Reciprocating Aircraft Engines § 33.34 Turbocharger rotors. Each turbocharger case must be designed and constructed to be able to contain fragments of a...

  10. 14 CFR 33.34 - Turbocharger rotors.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... 14 Aeronautics and Space 1 2013-01-01 2013-01-01 false Turbocharger rotors. 33.34 Section 33.34... STANDARDS: AIRCRAFT ENGINES Design and Construction; Reciprocating Aircraft Engines § 33.34 Turbocharger rotors. Each turbocharger case must be designed and constructed to be able to contain fragments of a...

  11. 14 CFR 33.34 - Turbocharger rotors.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... 14 Aeronautics and Space 1 2011-01-01 2011-01-01 false Turbocharger rotors. 33.34 Section 33.34... STANDARDS: AIRCRAFT ENGINES Design and Construction; Reciprocating Aircraft Engines § 33.34 Turbocharger rotors. Each turbocharger case must be designed and constructed to be able to contain fragments of a...

  12. 14 CFR 33.34 - Turbocharger rotors.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... 14 Aeronautics and Space 1 2012-01-01 2012-01-01 false Turbocharger rotors. 33.34 Section 33.34... STANDARDS: AIRCRAFT ENGINES Design and Construction; Reciprocating Aircraft Engines § 33.34 Turbocharger rotors. Each turbocharger case must be designed and constructed to be able to contain fragments of a...

  13. 14 CFR 33.34 - Turbocharger rotors.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... 14 Aeronautics and Space 1 2014-01-01 2014-01-01 false Turbocharger rotors. 33.34 Section 33.34... STANDARDS: AIRCRAFT ENGINES Design and Construction; Reciprocating Aircraft Engines § 33.34 Turbocharger rotors. Each turbocharger case must be designed and constructed to be able to contain fragments of a...

  14. 29 CFR 1926.758 - Systems-engineered metal buildings.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ..., DEPARTMENT OF LABOR (CONTINUED) SAFETY AND HEALTH REGULATIONS FOR CONSTRUCTION Steel Erection § 1926.758... systems-engineered metal buildings except §§ 1926.755 (column anchorage) and 1926.757 (open web steel... hoisting equipment is released. (d) Construction loads shall not be placed on any structural steel...

  15. 29 CFR 1926.758 - Systems-engineered metal buildings.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ..., DEPARTMENT OF LABOR (CONTINUED) SAFETY AND HEALTH REGULATIONS FOR CONSTRUCTION Steel Erection § 1926.758... systems-engineered metal buildings except §§ 1926.755 (column anchorage) and 1926.757 (open web steel... hoisting equipment is released. (d) Construction loads shall not be placed on any structural steel...

  16. 29 CFR 1926.758 - Systems-engineered metal buildings.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ..., DEPARTMENT OF LABOR (CONTINUED) SAFETY AND HEALTH REGULATIONS FOR CONSTRUCTION Steel Erection § 1926.758... systems-engineered metal buildings except §§ 1926.755 (column anchorage) and 1926.757 (open web steel... hoisting equipment is released. (d) Construction loads shall not be placed on any structural steel...

  17. 48 CFR 1836.602 - Selection of firms for architect-engineer contracts.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... architect-engineer contracts. 1836.602 Section 1836.602 Federal Acquisition Regulations System NATIONAL AERONAUTICS AND SPACE ADMINISTRATION SPECIAL CATEGORIES OF CONTRACTING CONSTRUCTION AND ARCHITECT-ENGINEER CONTRACTS Architect-Engineer Services 1836.602 Selection of firms for architect-engineer contracts. ...

  18. 48 CFR 836.602 - Selection of firms for architect-engineer contracts.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... architect-engineer contracts. 836.602 Section 836.602 Federal Acquisition Regulations System DEPARTMENT OF VETERANS AFFAIRS SPECIAL CATEGORIES OF CONTRACTING CONSTRUCTION AND ARCHITECT-ENGINEER CONTRACTS Architect-Engineer Services 836.602 Selection of firms for architect-engineer contracts. ...

  19. 48 CFR 1836.602 - Selection of firms for architect-engineer contracts.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... architect-engineer contracts. 1836.602 Section 1836.602 Federal Acquisition Regulations System NATIONAL AERONAUTICS AND SPACE ADMINISTRATION SPECIAL CATEGORIES OF CONTRACTING CONSTRUCTION AND ARCHITECT-ENGINEER CONTRACTS Architect-Engineer Services 1836.602 Selection of firms for architect-engineer contracts. ...

  20. 48 CFR 1436.602 - Selection of firms for architect-engineer contracts.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... architect-engineer contracts. 1436.602 Section 1436.602 Federal Acquisition Regulations System DEPARTMENT OF THE INTERIOR SPECIAL CATEGORIES OF CONTRACTING CONSTRUCTION AND ARCHITECT-ENGINEER CONTRACTS Architect-Engineer Services 1436.602 Selection of firms for architect-engineer contracts. ...

  1. 48 CFR 1436.602 - Selection of firms for architect-engineer contracts.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... architect-engineer contracts. 1436.602 Section 1436.602 Federal Acquisition Regulations System DEPARTMENT OF THE INTERIOR SPECIAL CATEGORIES OF CONTRACTING CONSTRUCTION AND ARCHITECT-ENGINEER CONTRACTS Architect-Engineer Services 1436.602 Selection of firms for architect-engineer contracts. ...

  2. 48 CFR 836.602 - Selection of firms for architect-engineer contracts.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... architect-engineer contracts. 836.602 Section 836.602 Federal Acquisition Regulations System DEPARTMENT OF VETERANS AFFAIRS SPECIAL CATEGORIES OF CONTRACTING CONSTRUCTION AND ARCHITECT-ENGINEER CONTRACTS Architect-Engineer Services 836.602 Selection of firms for architect-engineer contracts. ...

  3. 48 CFR 1436.602 - Selection of firms for architect-engineer contracts.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... architect-engineer contracts. 1436.602 Section 1436.602 Federal Acquisition Regulations System DEPARTMENT OF THE INTERIOR SPECIAL CATEGORIES OF CONTRACTING CONSTRUCTION AND ARCHITECT-ENGINEER CONTRACTS Architect-Engineer Services 1436.602 Selection of firms for architect-engineer contracts. ...

  4. 48 CFR 1836.602 - Selection of firms for architect-engineer contracts.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... architect-engineer contracts. 1836.602 Section 1836.602 Federal Acquisition Regulations System NATIONAL AERONAUTICS AND SPACE ADMINISTRATION SPECIAL CATEGORIES OF CONTRACTING CONSTRUCTION AND ARCHITECT-ENGINEER CONTRACTS Architect-Engineer Services 1836.602 Selection of firms for architect-engineer contracts. ...

  5. 48 CFR 1836.602 - Selection of firms for architect-engineer contracts.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... architect-engineer contracts. 1836.602 Section 1836.602 Federal Acquisition Regulations System NATIONAL AERONAUTICS AND SPACE ADMINISTRATION SPECIAL CATEGORIES OF CONTRACTING CONSTRUCTION AND ARCHITECT-ENGINEER CONTRACTS Architect-Engineer Services 1836.602 Selection of firms for architect-engineer contracts. ...

  6. 48 CFR 1436.602 - Selection of firms for architect-engineer contracts.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... architect-engineer contracts. 1436.602 Section 1436.602 Federal Acquisition Regulations System DEPARTMENT OF THE INTERIOR SPECIAL CATEGORIES OF CONTRACTING CONSTRUCTION AND ARCHITECT-ENGINEER CONTRACTS Architect-Engineer Services 1436.602 Selection of firms for architect-engineer contracts. ...

  7. 48 CFR 1836.602 - Selection of firms for architect-engineer contracts.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... architect-engineer contracts. 1836.602 Section 1836.602 Federal Acquisition Regulations System NATIONAL AERONAUTICS AND SPACE ADMINISTRATION SPECIAL CATEGORIES OF CONTRACTING CONSTRUCTION AND ARCHITECT-ENGINEER CONTRACTS Architect-Engineer Services 1836.602 Selection of firms for architect-engineer contracts. ...

  8. 48 CFR 1436.602 - Selection of firms for architect-engineer contracts.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... architect-engineer contracts. 1436.602 Section 1436.602 Federal Acquisition Regulations System DEPARTMENT OF THE INTERIOR SPECIAL CATEGORIES OF CONTRACTING CONSTRUCTION AND ARCHITECT-ENGINEER CONTRACTS Architect-Engineer Services 1436.602 Selection of firms for architect-engineer contracts. ...

  9. 48 CFR 836.602 - Selection of firms for architect-engineer contracts.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... architect-engineer contracts. 836.602 Section 836.602 Federal Acquisition Regulations System DEPARTMENT OF VETERANS AFFAIRS SPECIAL CATEGORIES OF CONTRACTING CONSTRUCTION AND ARCHITECT-ENGINEER CONTRACTS Architect-Engineer Services 836.602 Selection of firms for architect-engineer contracts. ...

  10. 48 CFR 836.602 - Selection of firms for architect-engineer contracts.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... architect-engineer contracts. 836.602 Section 836.602 Federal Acquisition Regulations System DEPARTMENT OF VETERANS AFFAIRS SPECIAL CATEGORIES OF CONTRACTING CONSTRUCTION AND ARCHITECT-ENGINEER CONTRACTS Architect-Engineer Services 836.602 Selection of firms for architect-engineer contracts. ...

  11. 48 CFR 836.602 - Selection of firms for architect-engineer contracts.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... architect-engineer contracts. 836.602 Section 836.602 Federal Acquisition Regulations System DEPARTMENT OF VETERANS AFFAIRS SPECIAL CATEGORIES OF CONTRACTING CONSTRUCTION AND ARCHITECT-ENGINEER CONTRACTS Architect-Engineer Services 836.602 Selection of firms for architect-engineer contracts. ...

  12. Biomimetic and synthetic esophageal tissue engineering.

    PubMed

    Jensen, Todd; Blanchette, Alex; Vadasz, Stephanie; Dave, Apeksha; Canfarotta, Michael; Sayej, Wael N; Finck, Christine

    2015-07-01

    A tissue-engineered esophagus offers an alternative for the treatment of pediatric patients suffering from severe esophageal malformations, caustic injury, and cancer. Additionally, adult patients suffering from carcinoma or trauma would benefit. Donor rat esophageal tissue was physically and enzymatically digested to isolate epithelial and smooth muscle cells, which were cultured in epithelial cell medium or smooth muscle cell medium and characterized by immunofluorescence. Isolated cells were also seeded onto electrospun synthetic PLGA and PCL/PLGA scaffolds in a physiologic hollow organ bioreactor. After 2 weeks of in vitro culture, tissue-engineered constructs were orthotopically transplanted. Isolated cells were shown to give rise to epithelial, smooth muscle, and glial cell types. After 14 days in culture, scaffolds supported epithelial, smooth muscle and glial cell phenotypes. Transplanted constructs integrated into the host's native tissue and recipients of the engineered tissue demonstrated normal feeding habits. Characterization after 14 days of implantation revealed that all three cellular phenotypes were present in varying degrees in seeded and unseeded scaffolds. We demonstrate that isolated cells from native esophagus can be cultured and seeded onto electrospun scaffolds to create esophageal constructs. These constructs have potential translatable application for tissue engineering of human esophageal tissue. Copyright © 2015 Elsevier Ltd. All rights reserved.

  13. Biomaterial-mesenchymal stem cell constructs for immunomodulation in composite tissue engineering.

    PubMed

    Hanson, Summer; D'Souza, Rena N; Hematti, Peiman

    2014-08-01

    Cell-based treatments are being developed as a novel approach for the treatment of many diseases in an effort to repair injured tissues and regenerate lost tissues. Interest in the potential use of multipotent progenitor or stem cells has grown significantly in recent years, specifically the use of mesenchymal stem cells (MSCs), for tissue engineering in combination with extracellular matrix-based scaffolds. An area that warrants further attention is the local or systemic host responses toward the implanted cell-biomaterial constructs. Such immunological responses could play a major role in determining the clinical efficacy of the therapeutic device or biomaterials used. MSCs, due to their unique immunomodulatory properties, hold great promise in tissue engineering as they not only directly participate in tissue repair and regeneration but also modulate the host foreign body response toward the engineered constructs. The purpose of this review was to summarize the current state of knowledge and applications of MSC-biomaterial constructs as a potential immunoregulatory tool in tissue engineering. Better understanding of the interactions between biomaterials and cells could translate to the development of clinically relevant and novel cell-based therapeutics for tissue reconstruction and regenerative medicine.

  14. An integrated theoretical-experimental approach to accelerate translational tissue engineering.

    PubMed

    Coy, Rachel H; Evans, Owen R; Phillips, James B; Shipley, Rebecca J

    2018-01-01

    Implantable devices utilizing bioengineered tissue are increasingly showing promise as viable clinical solutions. The design of bioengineered constructs is currently directed according to the results of experiments that are used to test a wide range of different combinations and spatial arrangements of biomaterials, cells and chemical factors. There is an outstanding need to accelerate the design process and reduce financial costs, whilst minimizing the required number of animal-based experiments. These aims could be achieved through the incorporation of mathematical modelling as a preliminary design tool. Here we focus on tissue-engineered constructs for peripheral nerve repair, which are designed to aid nerve and blood vessel growth and repair after peripheral nerve injury. We offer insight into the role that mathematical modelling can play within tissue engineering, and motivate the use of modelling as a tool capable of improving and accelerating the design of nerve repair constructs in particular. Specific case studies are presented in order to illustrate the potential of mathematical modelling to direct construct design. Copyright © 2016 The Authors Journal of Tissue Engineering and Regenerative Medicine Published by John Wiley & Sons Ltd. Copyright © 2016 The Authors Journal of Tissue Engineering and Regenerative Medicine Published by John Wiley & Sons Ltd.

  15. Constructed Wetlands

    EPA Pesticide Factsheets

    these systems can improve water quality, engineers and scientists construct systems that replicate the functions of natural wetlands. Constructed wetlands are treatment systems that use natural processes

  16. SWITCH: a dynamic CRISPR tool for genome engineering and metabolic pathway control for cell factory construction in Saccharomyces cerevisiae.

    PubMed

    Vanegas, Katherina García; Lehka, Beata Joanna; Mortensen, Uffe Hasbro

    2017-02-08

    The yeast Saccharomyces cerevisiae is increasingly used as a cell factory. However, cell factory construction time is a major obstacle towards using yeast for bio-production. Hence, tools to speed up cell factory construction are desirable. In this study, we have developed a new Cas9/dCas9 based system, SWITCH, which allows Saccharomyces cerevisiae strains to iteratively alternate between a genetic engineering state and a pathway control state. Since Cas9 induced recombination events are crucial for SWITCH efficiency, we first developed a technique TAPE, which we have successfully used to address protospacer efficiency. As proof of concept of the use of SWITCH in cell factory construction, we have exploited the genetic engineering state of a SWITCH strain to insert the five genes necessary for naringenin production. Next, the naringenin cell factory was switched to the pathway control state where production was optimized by downregulating an essential gene TSC13, hence, reducing formation of a byproduct. We have successfully integrated two CRISPR tools, one for genetic engineering and one for pathway control, into one system and successfully used it for cell factory construction.

  17. Arterial specification of endothelial cells derived from human induced pluripotent stem cells in a biomimetic flow bioreactor.

    PubMed

    Sivarapatna, Amogh; Ghaedi, Mahboobe; Le, Andrew V; Mendez, Julio J; Qyang, Yibing; Niklason, Laura E

    2015-01-01

    Endothelial cells (ECs) exist in different microenvironments in vivo, including under different levels of shear stress in arteries versus veins. Standard stem cell differentiation protocols to derive ECs and EC-subtypes from human induced pluripotent stem cells (hiPSCs) generally use growth factors or other soluble factors in an effort to specify cell fate. In this study, a biomimetic flow bioreactor was used to subject hiPSC-derived ECs (hiPSC-ECs) to shear stress to determine the impacts on phenotype and upregulation of markers associated with an anti-thrombotic, anti-inflammatory, arterial-like phenotype. The in vitro bioreactor system was able to efficiently mature hiPSC-ECs into arterial-like cells in 24 h, as demonstrated by qRT-PCR for arterial markers EphrinB2, CXCR4, Conexin40 and Notch1, as well protein-level expression of Notch1 intracellular domain (NICD). Furthermore, the exogenous addition of soluble factors was not able to fully recapitulate this phenotype that was imparted by shear stress exposure. The induction of these phenotypic changes was biomechanically mediated in the shear stress bioreactor. This biomimetic flow bioreactor is an effective means for the differentiation of hiPSC-ECs toward an arterial-like phenotype, and is amenable to scale-up for culturing large quantities of cells for tissue engineering applications. Copyright © 2015 Elsevier Ltd. All rights reserved.

  18. The Crosstalk between Tissue Engineering and Pharmaceutical Biotechnology: Recent Advances and Future Directions.

    PubMed

    Pacheco, Daniela P; Reis, Rui L; Correlo, Vítor M; Marques, Alexandra P

    2015-01-01

    Tissue-engineered constructs made of biotechnology-derived materials have been preferred due to their chemical and physical composition, which offers both high versatility and a support to enclose/ incorporate relevant signaling molecules and/or genes known to therapeutically induce tissue repair. Herein, a critical overview of the impact of different biotechnology-derived materials, scaffolds, and recombinant signaling molecules over the behavior of cells, another element of tissue engineered constructs, as well its regulatory role in tissue regeneration and disease progression is given. Additionally, these tissue-engineered constructs evolved to three-dimensional (3D) tissue-like models that, as an advancement of two-dimensional standard culture methods, are expected to be a valuable tool in the field of drug discovery and pharmaceutical research. Despite the improved design and conception of current proposed 3D tissue-like models, advanced control systems to enable and accelerate streamlining and automation of the numerous labor-intensive steps intrinsic to the development of tissue-engineered constructs are still to be achieved. In this sense, this review intends to present the biotechnology- derived materials that are being explored in the field of tissue engineering to generate 3D tissue-analogues and briefly highlight their foremost breakthroughs in tissue regeneration and drug discovery. It also aims to reinforce that the crosstalk between tissue engineering and pharmaceutical biotechnology has been fostering the outcomes of tissue engineering approaches through the use of biotechnology-derived signaling molecules. Gene delivery/therapy is also discussed as a forefront area that represents another cross point between tissue engineering and pharmaceutical biotechnology, in which nucleic acids can be considered a "super pharmaceutical" to drive biological responses, including tissue regeneration.

  19. Processes in construction of failure management expert systems from device design information

    NASA Technical Reports Server (NTRS)

    Malin, Jane T.; Lance, Nick

    1987-01-01

    This paper analyzes the tasks and problem solving methods used by an engineer in constructing a failure management expert system from design information about the device to te diagnosed. An expert test engineer developed a trouble-shooting expert system based on device design information and experience with similar devices, rather than on specific expert knowledge gained from operating the device or troubleshooting its failures. The construction of the expert system was intensively observed and analyzed. This paper characterizes the knowledge, tasks, methods, and design decisions involved in constructing this type of expert system, and makes recommendations concerning tools for aiding and automating construction of such systems.

  20. 48 CFR 227.7107 - Contracts for architect-engineer services.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ...-engineer services. 227.7107 Section 227.7107 Federal Acquisition Regulations System DEFENSE ACQUISITION... Rights in Technical Data 227.7107 Contracts for architect-engineer services. This section sets forth... of construction and architect-engineer services. ...

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