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Sample records for piezoelectric bone substitute

  1. Development of a piezoelectric bone substitute material

    CERN Document Server

    Al-Bader, Y A

    2000-01-01

    The thesis deals with the preparation and testing of ceramic compositions to be used as bone substitute. The proposed composition consisted of calcium enriched calcium phosphate, kaolin and barium titanate in different ratios. The homogeneous powder mixture was dry pressed at different pressures and fired at temperatures up to 1350 degC for different soaking times. The physical properties of the fired compacts that were tested are bulk density and porosity. These were determined as function of pressing pressure, firing temperature and soaking time for different compositions. The mechanical properties investigated were the ultimate compressive strength and Young's modulus, which were determined for different compositions and forming pressures. The electrical properties investigated were D.C. characteristics (resistivity) and A.C. characteristics (A.C. resistivity, dielectric constant, dielectric loss and loss tangent). The piezoelectric behaviour of the fired compacts was investigated and the piezoelectric coe...

  2. Bone substitute biomaterials

    CERN Document Server

    Mallick, K

    2014-01-01

    Bone substitute biomaterials are fundamental to the biomedical sector, and have recently benefitted from extensive research and technological advances aimed at minimizing failure rates and reducing the need for further surgery. This book reviews these developments, with a particular focus on the desirable properties for bone substitute materials and their potential to encourage bone repair and regeneration. Part I covers the principles of bone substitute biomaterials for medical applications. One chapter reviews the quantification of bone mechanics at the whole-bone, micro-scale, and non-scale levels, while others discuss biomineralization, osteoductivization, materials to fill bone defects, and bioresorbable materials. Part II focuses on biomaterials as scaffolds and implants, including multi-functional scaffolds, bioceramics, and titanium-based foams. Finally, Part III reviews further materials with the potential to encourage bone repair and regeneration, including cartilage grafts, chitosan, inorganic poly...

  3. Dielectric and Piezoelectric Properties of Sodium Bismuth Titanate Ceramics with KCe Substitution

    Institute of Scientific and Technical Information of China (English)

    XU Jian-Xiu; ZHAO Liang; ZHANG Cheng-Ju

    2008-01-01

    @@ The piezoelectric properties of the (KCe)-substituted sodium bismuth titanate (Na0.5Bi4.5 Ti4O15, NBT) piezo-electric ceramics are investigated. The piezoelectric properties of NBT ceramics are significantly enhanced by (KCe) substitution. The Curie temperature Tc, and piezoelectric coefficient d33 for the (KCe)-substituted NBT are found to be 663°C, and 27pC/N, respectively. Dielectric and annealing spectroscopy present that the (KCe) co-substituted NBT piezoelectric ceramics possess stable piezoelectric properties.

  4. Bone-inducing Activity of Biological Piezoelectric Ceramic

    Institute of Scientific and Technical Information of China (English)

    2005-01-01

    To simulate the piezoelectric effect of nature bone, two kinds of biological piezoelectric composite ceramics consisted of hydroxyapatite ( HA ) and lithium sodium potassium riobate (LNK) ceramic of which the ratio of HA/ LNK was 1: 10 and 5:5( wt/ wt ) were prepared. Their piezoelectric property and growth of apatite crystal in the ceramics surface were investigated. With the increase of LNK amount, piezoelectric activity increased correspondingly. By immersing the poled piezoelectric ceramics in simulated body fluid (SBF) at 36.5 ℃ for 7,14, and 21 days, apatite crystal was formed on negatively charged surfaces. After 21 days immersion in SBF,the thickest apatite crystal on the negatively charged surfaces increased to 3.337μm. The novel biological piezoelectric ceramics show an excellent piezoelectric property and superior potential bioactivity.

  5. LONG TERM EVOLUTION OF BONE RECONSTRUCTION WITH BONE GRAFT SUBSTITUTES

    Directory of Open Access Journals (Sweden)

    O. V. Martynenko

    2017-06-01

    Full Text Available The review involves clinical and experimental data, constitutive modeling, and computational investigations towards an understanding on how mechanical cyclic loads for long periods of time affect damage evolution in a reconstructed bone, as well as, lifetime reduction of bone graft substitutes after advanced core decompression. The outcome of the integrated model discussed in this paper will be how damage growth in femur after advanced core decompression subjected to mechanical cyclic loading under creep and fatigue conditions may be controlled in order to optimize design and processing of bone graft substitutes, and extend lifetime of bone substitutes.

  6. Polarization and Piezoelectric Properties of a Nitrile Substituted Polyimide

    Science.gov (United States)

    Simpson, Joycelyn; Ounaies, Zoubeida; Fay, Catharine

    1997-01-01

    This research focuses on the synthesis and characterization of a piezoelectric (beta-CN)- APB/ODPA polyimide. The remanent polarization and piezoelectric d(sub 31) and g(sub 33) coefficients are reported to assess the effect of synthesis variations. Each of the materials exhibits a level of piezoelectricity which increases with temperature. The remanent polarization is retained at temperatures close to the glass transition temperature of the polyimide.

  7. Composite bone substitutes prepared by two methods

    Science.gov (United States)

    Lee, Hoe Y.

    A variety of ceramics and polymers exists that can be used as bone substitute materials with desirable properties such as biocompatibility and osteoconductivity. A key feature missing in these bone substitutes, or scaffolds, is the ability to bear loads. This work explored two methods for solving this problem. The first used cancellous bone taken from bovine femoral bone to create a natural scaffold through a heat treating process that eliminated the organic components and sintered the bone minerals, known as hydroxyapatite, together. The strength and Young's modulus of the natural scaffold were greatly improved after polymer infiltration with polymethylmethacrylate. Unfortunately, compression testing revealed that there was not a good interfacial bond between the mineral and polymer phases. The second method employed a freeze-casting technique to create synthetic hydroxyapatite scaffolds that have an aligned lamellar microstructure. By varying the amount of hydroxyapatite in the initial slurry mixture and the cooling rate, synthetic scaffolds with a range of porosities and strengths was produced. The highest solid loading and fastest cooling rate produced a scaffold with a strength and modulus approaching that of cortical bone. Further study is required to produce a two phase composite that is chemically bonded together for optimal performance. The synthetic scaffolds, with their tunable mechanical properties and ease of fabrication, make them a promising material for a load-bearing bone substitute.

  8. Bone graft substitutes: past, present, future.

    Directory of Open Access Journals (Sweden)

    Parikh S

    2002-04-01

    Full Text Available Bone grafts are necessary to provide support, fill voids, and enhance biologic repair of skeletal defects. They are used by orthopaedic surgeons, neurosurgeons, craniofacial surgeons, and periodontists. Bone harvested from donor sites is the gold standard for this procedure. It is well documented that there are limitations and complications from the use of autograft, including the limited quantity and associated chronic donor site pain. Despite the increase in the number of procedures that require bone grafts, there has not been a single ideal bone graft substitute Scientists, surgeons, and medical companies, thus, have a tremendous responsibility to develop biologic alternatives that will enhance the functional capabilities of the bone graft substitute, and potentially reduce or eliminate the need for autograft. This article is an attempt to review the past and existing bone graft substitutes, and future directions of research. The historical data was extracted after thorough review of the literature. The data for the current concepts and future directions was compiled from the Internet, and from direct correspondence with medical companies. Since many products are undergoing clinical trials, and are yet not commercially available, their data cannot be found in literature. The main purpose of this article is to give the reader an idea about the existing market products and products likely to be available in near future.

  9. Fabrication and in vitro biological properties of piezoelectric bioceramics for bone regeneration.

    Science.gov (United States)

    Tang, Yufei; Wu, Cong; Wu, Zixiang; Hu, Long; Zhang, Wei; Zhao, Kang

    2017-02-27

    The piezoelectric effect of biological piezoelectric materials promotes bone growth. However, the material should be subjected to stress before it can produce an electric charge that promotes bone repair and reconstruction conducive to fracture healing. A novel method for in vitro experimentation of biological piezoelectric materials with physiological load is presented. A dynamic loading device that can simulate the force of human motion and provide periodic load to piezoelectric materials when co-cultured with cells was designed to obtain a realistic expression of piezoelectric effect on bone repair. Hydroxyapatite (HA)/barium titanate (BaTiO3) composite materials were fabricated by slip casting, and their piezoelectric properties were obtained by polarization. The d33 of HA/BaTiO3 piezoelectric ceramics after polarization was 1.3 pC/N to 6.8 pC/N with BaTiO3 content ranging from 80% to 100%. The in vitro biological properties of piezoelectric bioceramics with and without cycle loading were investigated. When HA/BaTiO3 piezoelectric bioceramics were affected by cycle loading, the piezoelectric effect of BaTiO3 promoted the growth of osteoblasts and interaction with HA, which was better than the effect of HA alone. The best biocompatibility and bone-inducing activity were demonstrated by the 10%HA/90%BaTiO3 piezoelectric ceramics.

  10. Bone Graft Substitutes : Developed for Trauma and Orthopaedic Surgery

    NARCIS (Netherlands)

    J. van der Stok (Johan)

    2015-01-01

    markdownabstract__Abstract__ Bone grafting was established in the 19th century and has become a common procedure in which bone defects are filled with bone grafts or bone graft substitutes. Bone defects that require bone grafting are encountered in approximately 10% of trauma and orthopaedic surger

  11. A New Piezoelectric Actuator Induces Bone Formation In Vivo: A Preliminary Study

    Directory of Open Access Journals (Sweden)

    Joana Reis

    2012-01-01

    Full Text Available This in vivo study presents the preliminary results of the use of a novel piezoelectric actuator for orthopedic application. The innovative use of the converse piezoelectric effect to mechanically stimulate bone was achieved with polyvinylidene fluoride actuators implanted in osteotomy cuts in sheep femur and tibia. The biological response around the osteotomies was assessed through histology and histomorphometry in nondecalcified sections and histochemistry and immunohistochemistry in decalcified sections, namely, through Masson's trichrome, and labeling of osteopontin, proliferating cell nuclear antigen, and tartrate-resistant acid phosphatase. After one-month implantation, total bone area and new bone area were significantly higher around actuators when compared to static controls. Bone deposition rate was also significantly higher in the mechanically stimulated areas. In these areas, osteopontin increased expression was observed. The present in vivo study suggests that piezoelectric materials and the converse piezoelectric effect may be used to effectively stimulate bone growth.

  12. Tissue reaction and material characteristics of four bone substitutes

    DEFF Research Database (Denmark)

    Jensen, S S; Aaboe, M; Pinholt, E M

    1996-01-01

    The aim of the present study was to qualitatively and quantitatively compare the tissue reactions around four different bone substitutes used in orthopedic and craniofacial surgery. Cylinders of two bovine bone substitutes (Endobon and Bio-Oss) and two coral-derived bone substitutes (Pro Osteon 500......-Oss was osseointegrated to a higher degree than the other biomaterials. Material characteristics obtained by diffuse reflectance infrared Fourier transform spectrometry analysis and energy-dispersive spectrometry did not explain the differences in biologic behavior....

  13. Preclinical evaluation of injectable bone substitute materials.

    Science.gov (United States)

    Bongio, Matilde; van den Beucken, Jeroen J J P; Leeuwenburgh, Sander C G; Jansen, John A

    2015-03-01

    Injectable bone substitutes (IBSs) represent an attractive class of ready-to-use biomaterials, both ceramic- and polymer-based, as they offer the potential benefit of minimally invasive surgery and optimal defect filling. Although in vitro assessments are the first step in the process of development, the safety and efficacy of an IBS strongly depend on validated preclinical research prior to clinical trials. However, the selection of a suitable preclinical model for performance evaluation of an IBS remains a challenge, as no gold standard exists to define the best animal model. In order to succeed in this attempt, we identified three stages of development, including (a) proof-of-principle, (b) predictive validity and (c) general scientific legitimacy, and the respective criteria that should be applied for such selection. The second part of this review provides an overview of commonly used animals for IBSs. Specifically, scientific papers published between January 1996 and March 2012 were retrieved that report the use of preclinical models for the evaluation of IBSs in situations requiring bone healing and bone augmentation. This review is meant not only to describe the currently available preclinical models for IBS application, but also to address critical considerations of such multi-factorial evaluation models (including animal species, strain, age, anatomical site, defect size and type of bone), which can be indicative but in most cases edge away from the human reality. Consequently, the ultimate goal is to guide researchers toward a more careful and meaningful interpretation of the results of experiments using animal models and their clinical applications. Copyright © 2012 John Wiley & Sons, Ltd.

  14. Stiffness compatibility of coralline hydroxyapatite bone substitute under dynamic loading

    Institute of Scientific and Technical Information of China (English)

    REN ChaoFeng; HOU ZhenDe; ZHAO Wei

    2009-01-01

    When hydroxyapatite bone substitutes are implanted in human bodies, bone tissues will grow into their porous structure, which will reinforce their strength and stiffness. The concept of mechanical com-patibility of bone substitutes implies that their mechanical properties are similar to the bone tissues around, as if they were part of the bone. The mechanical compatibility of bone substitutes includes both static and dynamic behavior, due to the mechanical properties of bone depending on the strain rate. In this study, split Hopkinson pressure bar technique (SHPB) was employed to determine the dy-namic mechanical properties of coralline hydroxyapatite, bones with and bones without organic com-ponents, and their dynamic stress-strain curves of the three materials were obtained. The mechanical effects of collagens in bone were assessed, by comparing the difference between the Young's moduli of the three materials. As the implanted bone substitute becomes a part of bone, it can be regarded as an inclusion composite. The effective modulus of the composite was also evaluated in order to estimate its mechanical compatibility on stiffness. The evaluated result shows that the suitable porosity of HA is0.8, which is in favor of both static and dynamic stiffness compatibility.

  15. Stiffness compatibility of coralline hydroxyapatite bone substitute under dynamic loading

    Institute of Scientific and Technical Information of China (English)

    2009-01-01

    When hydroxyapatite bone substitutes are implanted in human bodies,bone tissues will grow into their porous structure,which will reinforce their strength and stiffness.The concept of mechanical com-patibility of bone substitutes implies that their mechanical properties are similar to the bone tissues around,as if they were part of the bone.The mechanical compatibility of bone substitutes includes both static and dynamic behavior,due to the mechanical properties of bone depending on the strain rate.In this study,split Hopkinson pressure bar technique(SHPB) was employed to determine the dy-namic mechanical properties of coralline hydroxyapatite,bones with and bones without organic com-ponents,and their dynamic stress-strain curves of the three materials were obtained.The mechanical effects of collagens in bone were assessed,by comparing the difference between the Young’s moduli of the three materials.As the implanted bone substitute becomes a part of bone,it can be regarded as an inclusion composite.The effective modulus of the composite was also evaluated in order to estimate its mechanical compatibility on stiffness.The evaluated result shows that the suitable porosity of HA is 0.8,which is in favor of both static and dynamic stiffness compatibility.

  16. Macroporous synthetic hydroxyapatite bioceramics for bone substitute applications

    CSIR Research Space (South Africa)

    Thomas, ME

    1999-08-01

    Full Text Available An improved strategy is described for the manufacture of macroporous hydroxyapatite bioceramics for bone substitute applications. This is based on a modified fugitive phase technique, which allows production of relatively open, high-strength devices...

  17. Piezoelectricity

    CERN Document Server

    Lubitz, Karl

    2008-01-01

    Piezoelectric materials play a key role in an innovative market. Advances in applications derive from new materials and their development, as well as to new market requirements. This report elucidates these developments by a broad spectrum of examples, comprising ultrasound in medicine and defence industry, and frequency control.

  18. Bone defect animal models for testing efficacy of bone substitute biomaterials

    Directory of Open Access Journals (Sweden)

    Ye Li

    2015-07-01

    Full Text Available Large bone defects are serious complications that are most commonly caused by extensive trauma, tumour, infection, or congenital musculoskeletal disorders. If nonunion occurs, implantation for repairing bone defects with biomaterials developed as a defect filler, which can promote bone regeneration, is essential. In order to evaluate biomaterials to be developed as bone substitutes for bone defect repair, it is essential to establish clinically relevant in vitro and in vivo testing models for investigating their biocompatibility, mechanical properties, degradation, and interactional with culture medium or host tissues. The results of the in vitro experiment contribute significantly to the evaluation of direct cell response to the substitute biomaterial, and the in vivo tests constitute a step midway between in vitro tests and human clinical trials. Therefore, it is essential to develop or adopt a suitable in vivo bone defect animal model for testing bone substitutes for defect repair. This review aimed at introducing and discussing the most available and commonly used bone defect animal models for testing specific substitute biomaterials. Additionally, we reviewed surgical protocols for establishing relevant preclinical bone defect models with various animal species and the evaluation methodologies of the bone regeneration process after the implantation of bone substitute biomaterials. This review provides an important reference for preclinical studies in translational orthopaedics.

  19. 3D Printing of Octacalcium Phosphate Bone Substitutes

    Science.gov (United States)

    Komlev, Vladimir S.; Popov, Vladimir K.; Mironov, Anton V.; Fedotov, Alexander Yu.; Teterina, Anastasia Yu.; Smirnov, Igor V.; Bozo, Ilya Y.; Rybko, Vera A.; Deev, Roman V.

    2015-01-01

    Biocompatible calcium phosphate ceramic grafts are able of supporting new bone formation in appropriate environment. The major limitation of these materials usage for medical implants is the absence of accessible methods for their patient-specific fabrication. 3D printing methodology is an excellent approach to overcome the limitation supporting effective and fast fabrication of individual complex bone substitutes. Here, we proposed a relatively simple route for 3D printing of octacalcium phosphates (OCP) in complexly shaped structures by the combination of inkjet printing with post-treatment methodology. The printed OCP blocks were further implanted in the developed cranial bone defect followed by histological evaluation. The obtained result confirmed the potential of the developed OCP bone substitutes, which allowed 2.5-time reducing of defect’s diameter at 6.5 months in a region where native bone repair is extremely inefficient. PMID:26106596

  20. 3D Printing of Octacalcium Phosphate Bone Substitutes.

    Science.gov (United States)

    Komlev, Vladimir S; Popov, Vladimir K; Mironov, Anton V; Fedotov, Alexander Yu; Teterina, Anastasia Yu; Smirnov, Igor V; Bozo, Ilya Y; Rybko, Vera A; Deev, Roman V

    2015-01-01

    Biocompatible calcium phosphate ceramic grafts are able of supporting new bone formation in appropriate environment. The major limitation of these materials usage for medical implants is the absence of accessible methods for their patient-specific fabrication. 3D printing methodology is an excellent approach to overcome the limitation supporting effective and fast fabrication of individual complex bone substitutes. Here, we proposed a relatively simple route for 3D printing of octacalcium phosphates (OCP) in complexly shaped structures by the combination of inkjet printing with post-treatment methodology. The printed OCP blocks were further implanted in the developed cranial bone defect followed by histological evaluation. The obtained result confirmed the potential of the developed OCP bone substitutes, which allowed 2.5-time reducing of defect's diameter at 6.5 months in a region where native bone repair is extremely inefficient.

  1. 3D printing of octacalcium phosphate bone substitutes

    Directory of Open Access Journals (Sweden)

    Vladimir S. Komlev

    2015-06-01

    Full Text Available Biocompatible calcium phosphate ceramic grafts are able of supporting new bone formation in appropriate environment. The major limitation of these materials usage for medical implants is the absence of accessible methods for their patient-specific fabrication. 3D printing methodology is an excellent approach to overcome the limitation supporting effective and fast fabrication of individual complex bone substitutes. Here we proposed a relatively simple route for 3D printing of octacalcium phosphates in complexly shaped structures by the combination of inkjet printing with post-treatment methodology. The printed octacalcium phosphate blocks were further implanted in the developed cranial bone defect followed by histological evaluation. The obtained result confirmed the potential of the developed octacalcium phosphates bone substitutes, which allowed 2.5-time reducing of defect’s diameter at 6.5 months in a region where native bone repair is extremely inefficient.

  2. Magnesium substitution in brushite cements for enhanced bone tissue regeneration

    Energy Technology Data Exchange (ETDEWEB)

    Cabrejos-Azama, Jatsue, E-mail: jacaza@farm.ucm.es [Departamento de Química-Física II, Facultad de Farmacia, UCM, Madrid (Spain); Departamento de Estomatología III, Facultad de Odontología UCM, Madrid (Spain); Alkhraisat, Mohammad Hamdan; Rueda, Carmen [Departamento de Química-Física II, Facultad de Farmacia, UCM, Madrid (Spain); Torres, Jesús [Facultad de Ciencias de la salud URJC, Alcorcón, Madrid (Spain); Blanco, Luis [Departamento de Estomatología III, Facultad de Odontología UCM, Madrid (Spain); López-Cabarcos, Enrique [Departamento de Química-Física II, Facultad de Farmacia, UCM, Madrid (Spain)

    2014-10-01

    We have synthesized calcium phosphate cements doped with different amounts of magnesium (Mg-CPC) with a twofold purpose: i) to evaluate in vitro the osteoblast cell response to this material, and ii) to compare the bone regeneration capacity of the doped material with a calcium cement prepared without magnesium (CPC). Cell proliferation and in vivo response increased in the Mg-CPCs in comparison with CPC. The Mg-CPCs have promoted higher new bone formation than the CPC (p < 0.05). The cytocompatibility and histomorfometric analysis performed in the rabbit calvaria showed that the incorporation of magnesium ions in CPC improves osteoblasts proliferation and provides higher new bone formation. The development of a bone substitute with controllable biodegradable properties and improved bone regeneration can be considered a step toward personalized therapy that can adapt to patient needs and clinical situations. - Highlights: • The Mg-CPCs promote higher new bone formation than the CPC. • The incorporation of magnesium ions in CPC improves osteoblasts proliferation. • Mg-CPC is a bone substitute with controllable biodegradable properties. • We suggest that the use of Mg ions could improve the clinical efficiency of CPCs.

  3. Magnesium substitution in brushite cements for enhanced bone tissue regeneration.

    Science.gov (United States)

    Cabrejos-Azama, Jatsue; Alkhraisat, Mohammad Hamdan; Rueda, Carmen; Torres, Jesús; Blanco, Luis; López-Cabarcos, Enrique

    2014-10-01

    We have synthesized calcium phosphate cements doped with different amounts of magnesium (Mg-CPC) with a twofold purpose: i) to evaluate in vitro the osteoblast cell response to this material, and ii) to compare the bone regeneration capacity of the doped material with a calcium cement prepared without magnesium (CPC). Cell proliferation and in vivo response increased in the Mg-CPCs in comparison with CPC. The Mg-CPCs have promoted higher new bone formation than the CPC (p<0.05). The cytocompatibility and histomorfometric analysis performed in the rabbit calvaria showed that the incorporation of magnesium ions in CPC improves osteoblasts proliferation and provides higher new bone formation. The development of a bone substitute with controllable biodegradable properties and improved bone regeneration can be considered a step toward personalized therapy that can adapt to patient needs and clinical situations.

  4. PIEZOELECTRIC BONE SURGERY: A REVIEW OF THE LITERATURE AND POTENTIAL APPLICATIONS IN VETERINARY OROMAXILLOFACIAL SURGERY

    Directory of Open Access Journals (Sweden)

    Philippe eHENNET

    2015-05-01

    Full Text Available Piezoelectric bone surgery is a recent and innovative technology permitting a selective cut of mineralized tissue while sparing soft tissue. Similar to a dental scaler, a high frequency vibration, in the range of 25-35kHz, is transmitted to a metallic tip. However, the power of the piezosurgical instrument is 3 to 6 times higher than that of a dental scaler. The major advantages of this technology include high precision, a design that increases ease of curvilinear osteotomy, less trauma to soft tissue, preservation of neurological and vascular structures, reduced hemorrhage, minimal thermal damage to the bone as well as overall improvement of healing. The handpiece of the instrument is equipped with a sterile irrigation system and light-emitting diode (LED light, which improves visibility and overall safety. Piezoelectric surgery is particularly useful when performing delicate bone procedures such as periodontal or endodontic surgery. It is also indicated when performing more invasive bone surgery such as maxillectomy, mandibulectomy, and condylectomy, where preservation of neurovascular structures is important. Piezoelectric instruments are different from rotary instrumentation or oscillating saws, they require light pressure with constant motion of the tip. Training is required to master the technique.

  5. Controlling Bone Graft Substitute Microstructure to Improve Bone Augmentation.

    Science.gov (United States)

    Sheikh, Zeeshan; Drager, Justin; Zhang, Yu Ling; Abdallah, Mohamed-Nur; Tamimi, Faleh; Barralet, Jake

    2016-07-01

    Vertical bone augmentation procedures are frequently carried out to allow successful placement of dental implants in otherwise atrophic ridges and represent one of the most common bone grafting procedures currently performed. Onlay autografting is one of the most prevalent and predictable techniques to achieve this; however, there are several well documented complications and drawbacks associated with it and synthetic alternatives are being sought. Monetite is a bioresorbable dicalcium phosphate with osteoconductive and osteoinductive potential that has been previously investigated for onlay bone grafting and it is routinely made by autoclaving brushite to simultaneously sterilize and phase convert. In this study, monetite disc-shaped grafts are produced by both wet and dry heating methods which alter their physical properties such as porosity, surface area, and mechanical strength. Histological observations after 12 weeks of onlay grafting on rabbit calvaria reveal higher bone volume (38%) in autoclaved monetite grafts in comparison with the dry heated monetite grafts (26%). The vertical bone height gained is similar for both the types of monetite grafts (up to 3.2 mm). However, it is observed that the augmented bone height is greater in the lateral than the medial areas of both types of monetite grafts. It is also noted that the higher porosity of autoclaved monetite grafts increases the bioresorbability, whereas the dry heated monetite grafts having lower porosity but higher surface area resorb to a significantly lesser extent. This study provides information regarding two types of monetite onlay grafts prepared with different physical properties that can be further investigated for clinical vertical bone augmentation applications.

  6. A piezoelectric actuator-driven loading device for mechanical condition during bone tissue engineering

    Science.gov (United States)

    Zhang, C. Q.; Wu, H.; Dong, X.

    2008-10-01

    Bone cells live in an environment heavily influenced by mechanical forces. The researches of bone cell responses in hard scaffolds under differently mechanical conditions will be greatly beneficial to elucidating the mechanisms of bone mechanotransduction as well as applications of mechanical condition in bone tissue engineering. However, the appropriate device for the experiments is prerequisite. A loading device suitable to hard scaffold for study on mechanical responses of bone cells was made by usage of a kind of long-travel, high-load piezoelectric actuator. The device, which is so small enough to work in a standard incubator, can cause hard scaffolds with directly uniaxial compressive strains with more magnitudes, frequency components, and waveforms, including bone physiologically mechanical state, precisely controlled by a computer. The device achieves precise mechanical conditions by testing verification. The device may produce a model that will be suitable for investigating the influences of mechanical responses on bone cells in 3D hard scaffolds in vitro matching that in cancellous bone in vivo and may be applied during bone tissue engineering culture.

  7. The use of bone grafts and bone graft substitutes in pediatric orthopaedics: an overview.

    Science.gov (United States)

    Gross, Richard H

    2012-01-01

    Bone graft substitutes have become progressively more widely used, and are currently heavily marketed. To make intelligent decisions, a complete knowledge of autograaft and allograft bone healing is essential, including the definition of "sterile". Differences in donor selection and tissue processing may confound the user not familiar with the implications of these different approaches. Specific products include demineralized bone matrix (DBM), specific growth factors (recombinant BMP's), ceramic grafts, and platelet-rich plasma (PRP). There are a number of useful applications of bone graft substitues for pediatric orthopaedists, but the data base is evolving. This paper describes the current status of these products.

  8. Physicochemical Characteristics of Bone Substitutes Used in Oral Surgery in Comparison to Autogenous Bone

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    Antoine Berberi

    2014-01-01

    Full Text Available Bone substitutes used in oral surgery include allografts, xenografts, and synthetic materials that are frequently used to compensate bone loss or to reinforce repaired bone, but little is currently known about their physicochemical characteristics. The aim of this study was to evaluate a number of physical and chemical properties in a variety of granulated mineral-based biomaterials used in dentistry and to compare them with those of autogenous bone. Autogenous bone and eight commercial biomaterials of human, bovine, and synthetic origins were studied by high-resolution X-ray diffraction, atomic absorption spectrometry, and laser diffraction to determine their chemical composition, calcium release concentration, crystallinity, and granulation size. The highest calcium release concentration was 24. 94 mg/g for Puros and the lowest one was 2.83 mg/g for Ingenios β-TCP compared to 20.15 mg/g for natural bone. The range of particles sizes, in terms of median size D50, varied between 1.32 μm for BioOss and 902.41 μm for OsteoSponge, compared to 282.1 μm for natural bone. All samples displayed a similar hexagonal shape as bone, except Ingenios β-TCP, Macrobone, and OsteoSponge, which showed rhomboid and triclinic shapes, respectively. Commercial bone substitutes significantly differ in terms of calcium concentration, particle size, and crystallinity, which may affect their in vivo performance.

  9. Enhancement of piezoelectric constants induced by cation-substitution and two-dimensional strain effects on ZnO predicted by density functional perturbation theory

    Science.gov (United States)

    Nakamura, Kaoru; Higuchi, Sadao; Ohnuma, Toshiharu

    2016-03-01

    Using density functional perturbation theory, we investigated the effect of various substitutional dopant elements and in-plane strain on the piezoelectric properties of ZnO. The piezoelectric stress constant e33 of doped ZnO was found to depend on the formal charge of the substitutional dopant. By decomposing the piezoelectric stress constant e33 into the individual atomic contributions, the change in the piezoelectric properties was found to originate from a change in the coupling between the atomic displacement and the strain. Furthermore, we found that in-plane tensile strain along the a axis, which is specific to the thin film, can enhance the piezoelectric constant of ZnO. A phase transition from wurtzite to h-BN-type structure was found to occur with increasing in-plane tensile. The piezoelectric strain constant d33 was predicted to reach ˜200 pC/N for 2.78 at. % V-substituted ZnO at 5.5% in-plane strain, just before the phase transition. These theoretical results suggest that the piezoelectric constant of ZnO can be enhanced by controlling the in-plane strain via selection of the substrate material and dopant element.

  10. Rapid prototyped porous nickel-titanium scaffolds as bone substitutes.

    Science.gov (United States)

    Hoffmann, Waldemar; Bormann, Therese; Rossi, Antonella; Müller, Bert; Schumacher, Ralf; Martin, Ivan; de Wild, Michael; Wendt, David

    2014-01-01

    While calcium phosphate-based ceramics are currently the most widely used materials in bone repair, they generally lack tensile strength for initial load bearing. Bulk titanium is the gold standard of metallic implant materials, but does not match the mechanical properties of the surrounding bone, potentially leading to problems of fixation and bone resorption. As an alternative, nickel-titanium alloys possess a unique combination of mechanical properties including a relatively low elastic modulus, pseudoelasticity, and high damping capacity, matching the properties of bone better than any other metallic material. With the ultimate goal of fabricating porous implants for spinal, orthopedic and dental applications, nickel-titanium substrates were fabricated by means of selective laser melting. The response of human mesenchymal stromal cells to the nickel-titanium substrates was compared to mesenchymal stromal cells cultured on clinically used titanium. Selective laser melted titanium as well as surface-treated nickel-titanium and titanium served as controls. Mesenchymal stromal cells had similar proliferation rates when cultured on selective laser melted nickel-titanium, clinically used titanium, or controls. Osteogenic differentiation was similar for mesenchymal stromal cells cultured on the selected materials, as indicated by similar gene expression levels of bone sialoprotein and osteocalcin. Mesenchymal stromal cells seeded and cultured on porous three-dimensional selective laser melted nickel-titanium scaffolds homogeneously colonized the scaffold, and following osteogenic induction, filled the scaffold's pore volume with extracellular matrix. The combination of bone-related mechanical properties of selective laser melted nickel-titanium with its cytocompatibility and support of osteogenic differentiation of mesenchymal stromal cells highlights its potential as a superior bone substitute as compared to clinically used titanium.

  11. Rapid prototyped porous nickel–titanium scaffolds as bone substitutes

    Directory of Open Access Journals (Sweden)

    Waldemar Hoffmann

    2014-06-01

    Full Text Available While calcium phosphate–based ceramics are currently the most widely used materials in bone repair, they generally lack tensile strength for initial load bearing. Bulk titanium is the gold standard of metallic implant materials, but does not match the mechanical properties of the surrounding bone, potentially leading to problems of fixation and bone resorption. As an alternative, nickel–titanium alloys possess a unique combination of mechanical properties including a relatively low elastic modulus, pseudoelasticity, and high damping capacity, matching the properties of bone better than any other metallic material. With the ultimate goal of fabricating porous implants for spinal, orthopedic and dental applications, nickel–titanium substrates were fabricated by means of selective laser melting. The response of human mesenchymal stromal cells to the nickel–titanium substrates was compared to mesenchymal stromal cells cultured on clinically used titanium. Selective laser melted titanium as well as surface-treated nickel–titanium and titanium served as controls. Mesenchymal stromal cells had similar proliferation rates when cultured on selective laser melted nickel–titanium, clinically used titanium, or controls. Osteogenic differentiation was similar for mesenchymal stromal cells cultured on the selected materials, as indicated by similar gene expression levels of bone sialoprotein and osteocalcin. Mesenchymal stromal cells seeded and cultured on porous three-dimensional selective laser melted nickel–titanium scaffolds homogeneously colonized the scaffold, and following osteogenic induction, filled the scaffold’s pore volume with extracellular matrix. The combination of bone-related mechanical properties of selective laser melted nickel–titanium with its cytocompatibility and support of osteogenic differentiation of mesenchymal stromal cells highlights its potential as a superior bone substitute as compared to clinically used

  12. No effect of Osteoset, a bone graft substitute, on bone healing in humans: a prospective randomized double-blind study

    DEFF Research Database (Denmark)

    Petruskevicius, Juozas; Nielsen, Mette Strange; Kaalund, Søren;

    2002-01-01

    We studied the effects of a newly marketed bone substitute, Osteoset, on bone healing in a tibial defect in humans. 20 patients undergoing an ACL (anterior cruciate ligament) reconstruction with bone-patella tendon-bone graft were block-randomized into 2 groups of 10 each. In the treatment group...

  13. Comparison of efficacies of different bone substitutes adhered to osteoblasts with and without extracellular matrix proteins

    Directory of Open Access Journals (Sweden)

    Li-Ling Tseng

    2013-12-01

    Conclusion: The results indicated that ECM proteins increased cell attachment to bone substitutes in vitro. The preferential affinity of different bone substitutes to certain ECM proteins was evident. Cerasorb and BoneCeramic had better MG63 human osteosarcoma cell adhesion ability than Bio-Oss and MBCP.

  14. Temperature Values Variability in Piezoelectric Implant Site Preparation: Differences between Cortical and Corticocancellous Bovine Bone

    Directory of Open Access Journals (Sweden)

    Luca Lamazza

    2016-01-01

    Full Text Available Purpose. Various parameters can influence temperature rise and detection during implant site preparation. The aim of this study is to investigate local temperature values in cortical and corticocancellous bovine bone during early stages of piezoelectric implant site preparation. Materials and Methods. 20 osteotomies were performed using a diamond tip (IM1s, Mectron Medical Technology, Carasco, Italy on two different types of bovine bone samples, cortical and corticocancellous, respectively. A standardized protocol was designed to provide constant working conditions. Temperatures were measured in real time at a fixed position by a fiber optic thermometer. Results. Significantly higher drilling time (154.90 sec versus 99.00 sec; p<0.0001 and temperatures (39.26°C versus 34.73°C; p=0.043 were observed in the cortical group compared to the corticocancellous group. A remarkable variability of results characterized the corticocancellous blocks as compared to the blocks of pure cortical bone. Conclusion. Bone samples can influence heat generation during in vitro implant site preparation. When compared to cortical bone, corticocancellous samples present more variability in temperature values. Even controlling most experimental factors, the impact of bone samples still remains one of the main causes of temperature variability.

  15. The effects of a novel-reinforced bone substitute and Colloss®E on bone defect healing in sheep

    DEFF Research Database (Denmark)

    Ding, Ming; Røjskjaer, Jesper; Cheng, Liming

    2012-01-01

    /β-TCP-PDLLA), Colloss®E, and combination of substitute with Colloss®E on bone formation in vivo were evaluated. Cylindrical critical size defects were created at distal femoral condyles bilaterally in sheep. Titanium implant with concentric gap filling with one of the four materials was inserted. After 9 weeks....... Significant new bone formation could be seen in vivo in all four groups and there were no significant differences between them. The PDLLA-reinforced substitute seems to be good alternative substitute material for bone healing in sheep. Further investigations should be performed to validate this novel...... substitute material....

  16. Biologic and clinical aspects of integration of different bone substitutes in oral surgery: a literature review.

    Science.gov (United States)

    Zizzari, Vincenzo Luca; Zara, Susi; Tetè, Giulia; Vinci, Raffaele; Gherlone, Enrico; Cataldi, Amelia

    2016-10-01

    Many bone substitutes have been proposed for bone regeneration, and researchers have focused on the interactions occurring between grafts and host tissue, as the biologic response of host tissue is related to the origin of the biomaterial. Bone substitutes used in oral and maxillofacial surgery could be categorized according to their biologic origin and source as autologous bone graft when obtained from the same individual receiving the graft; homologous bone graft, or allograft, when harvested from an individual other than the one receiving the graft; animal-derived heterologous bone graft, or xenograft, when derived from a species other than human; and alloplastic graft, made of bone substitute of synthetic origin. The aim of this review is to describe the most commonly used bone substitutes, according to their origin, and to focus on the biologic events that ultimately lead to the integration of a biomaterial with the host tissue.

  17. Development of bioactive materials using reticulated ceramics for bone substitute

    Science.gov (United States)

    Jiang, Gengwei

    For hard tissue prosthetics, it is necessary to seek novel synthesis routes by which a real structural bone can be simulated in terms of bioactivity, porosity, and mechanical behavior. The work presented here deals with the development of such a component by a novel synthesis route for bone implantation. To enhance the mechanical properties, an industrial alumina has been selected as the substrate. Alumina is not only bio inert but also mechanically strong which makes it an ideal substrate for bone substitute. The high porosity is achieved via a sponge technique by which both pore size and density can be changed easily. The bioactivity is induced by coating a highly bioactive HA film onto the inner pore surfaces of the reticulated alumina. Based on this concept, the research has focused on the coating of HA onto inner pore surfaces of the reticulated alumina via several effective methods that are developed in our laboratory. No previous studies have so far been reported on coating inner surfaces of small-diameter pores ranging from 0.1--1.0 mm. The key materials processing issues dealt with in this work include precursor chemistry, coating procedures, synthesis of coated component, interface structure study, film adhesion strength testing, and mechanical properties of the component. This novel approach has shown great promise in synthesizing bone substitutes. To determine the applicability of the coated component in hard tissue prosthetics, a bioactivity study has been carried out. By immersing the synthetic HA into simulated body fluid (SBF), the bioresponse has been measured for a variety of samples with different processing conditions. Fundamental aspects of this study are centered on the effects of structural characteristics of HA on the bioactivity. Based on extensive IR and XRD experimental data, it has been found that the bioactivity of HA is sensitively controlled by the structural crystallinity of the HA and its specific surface area. Furthermore, based on

  18. Morphological Aspect and iNOS and Bax Expression Modification in Bone Tissue Around Dental Implants Positioned Using Piezoelectric Bone Surgery Versus Conventional Drill Technique.

    Science.gov (United States)

    Zizzari, Vincenzo Luca; Berardi, Davide; Congedi, Francesca; Tumedei, Margherita; Cataldi, Amelia; Perfetti, Giorgio

    2015-05-01

    The aim of this work is to evaluate differences occurring in bone tissue around dental implants positioned using piezoelectric or conventional drill technique. Twenty-four implants were inserted bilaterally in the iliac crest of 6 sheep after site preparation through a piezoelectric instrument (Test) or after site preparation through conventional drill technique with rotary instruments (Control). Animals were randomly divided to be euthanized at 15 and 30 days post-intervention (p.i.); peri-implant bone samples were withdrawn and processed for histological analysis and immunohistochemical evaluation of iNOS and Bax expression. Active remodeling phenomena in both Test and Control samples are showed at 15 days p.i., while at 30 days p.i., the overall organization of the peri-implant bone resembles native bone tissue. Immunohistochemical evaluation reveals a statistically significant increase of both iNOS and Bax expression at 15 days p.i. compared to samples obtained 30 days p.i. and to native bone. At both healing times, a higher but not statistically significant iNOS and Bax expression is recorded in samples from Control compared to Test Group. Even if the insertion protocol does not seem to significantly interfere with the long-term healing process, implant site preparation through the piezoelectric bone surgery technique may allow a reduction of peri-implant bone tissue inflammation and support a more rapid bone tissue healing phase.

  19. Development and mechanical characterization of porous titanium bone substitutes.

    Science.gov (United States)

    Barbas, A; Bonnet, A-S; Lipinski, P; Pesci, R; Dubois, G

    2012-05-01

    Commercially Pure Porous Titanium (CPPTi) can be used for surgical implants to avoid the stress shielding effect due to the mismatch between the mechanical properties of titanium and bone. Most researchers in this area deal with randomly distributed pores or simple architectures in titanium alloys. The control of porosity, pore size and distribution is necessary to obtain implants with mechanical properties close to those of bone and to ensure their osseointegration. The aim of the present work was therefore to develop and characterize such a specific porous structure. First of all, the properties of titanium made by Selective Laser Melting (SLM) were characterized through experimental testing on bulk specimens. An elementary pattern of the porous structure was then designed to mimic the orthotropic properties of the human bone following several mechanical and geometrical criteria. Finite Element Analysis (FEA) was used to optimize the pattern. A porosity of 53% and pore sizes in the range of 860 to 1500 μm were finally adopted. Tensile tests on porous samples were then carried out to validate the properties obtained numerically and identify the failure modes of the samples. Finally, FE elastoplastic analyses were performed on the porous samples in order to propose a failure criterion for the design of porous substitutes.

  20. Effects of a perfusion bioreactor activated novel bone substitute in spine fusion in sheep

    DEFF Research Database (Denmark)

    Sørensen, Jesper Roed; Koroma, Kariatta Ester; Ding, Ming

    2012-01-01

    To evaluate the effect of a large perfusion-bioreactor cell-activated bone substitute, on a two-level large posterolateral spine fusion sheep model.......To evaluate the effect of a large perfusion-bioreactor cell-activated bone substitute, on a two-level large posterolateral spine fusion sheep model....

  1. Synthetic bone substitute engineered with amniotic epithelial cells enhances bone regeneration after maxillary sinus augmentation.

    Directory of Open Access Journals (Sweden)

    Barbara Barboni

    Full Text Available BACKGROUND: Evidence has been provided that a cell-based therapy combined with the use of bioactive materials may significantly improve bone regeneration prior to dental implant, although the identification of an ideal source of progenitor/stem cells remains to be determined. AIM: In the present research, the bone regenerative property of an emerging source of progenitor cells, the amniotic epithelial cells (AEC, loaded on a calcium-phosphate synthetic bone substitute, made by direct rapid prototyping (rPT technique, was evaluated in an animal study. MATERIAL AND METHODS: Two blocks of synthetic bone substitute (∼0.14 cm(3, alone or engineered with 1×10(6 ovine AEC (oAEC, were grafted bilaterally into maxillary sinuses of six adult sheep, an animal model chosen for its high translational value in dentistry. The sheep were then randomly divided into two groups and sacrificed at 45 and 90 days post implantation (p.i.. Tissue regeneration was evaluated in the sinus explants by micro-computer tomography (micro-CT, morphological, morphometric and biochemical analyses. RESULTS AND CONCLUSIONS: The obtained data suggest that scaffold integration and bone deposition are positively influenced by allotransplantated oAEC. Sinus explants derived from sheep grafted with oAEC engineered scaffolds displayed a reduced fibrotic reaction, a limited inflammatory response and an accelerated process of angiogenesis. In addition, the presence of oAEC significantly stimulated osteogenesis either by enhancing bone deposition or making more extent the foci of bone nucleation. Besides the modulatory role played by oAEC in the crucial events successfully guiding tissue regeneration (angiogenesis, vascular endothelial growth factor expression and inflammation, data provided herein show that oAEC were also able to directly participate in the process of bone deposition, as suggested by the presence of oAEC entrapped within the newly deposited osteoid matrix and by their

  2. Blast-induced electromagnetic fields in the brain from bone piezoelectricity.

    Science.gov (United States)

    Lee, Ka Yan Karen; Nyein, Michelle K; Moore, David F; Joannopoulos, J D; Socrate, Simona; Imholt, Timothy; Radovitzky, Raul; Johnson, Steven G

    2011-01-01

    In this paper, we show that bone piezoelectricity-a phenomenon in which bone polarizes electrically in response to an applied mechanical stress and produces a short-range electric field-may be a source of intense blast-induced electric fields in the brain, with magnitudes and timescales comparable to fields with known neurological effects. We compute the induced charge density in the skull from stress data on the skull from a finite-element full-head model simulation of a typical IED-scale blast wave incident on an unhelmeted human head as well as a human head protected by a kevlar helmet, and estimate the resulting electric fields in the brain in both cases to be on the order of 10 V/m in millisecond pulses. These fields are more than 10 times stronger than the IEEE safety guidelines for controlled environments (IEEE Standards Coordinating Committee 28, 2002) and comparable in strength and timescale to fields from repetitive Transcranial Magnetic Stimulation (rTMS) that are designed to induce neurological effects (Wagner et al., 2006a). They can be easily measured by RF antennas, and may provide the means to design a diagnostic tool that records a quantitative measure of the head's exposure to blast insult.

  3. Novel bone substitute material in alveolar bone healing following tooth extraction: an experimental study in sheep.

    Science.gov (United States)

    Liu, Jinyi; Schmidlin, Patrick R; Philipp, Alexander; Hild, Nora; Tawse-Smith, Andrew; Duncan, Warwick

    2016-07-01

    Electrospun cotton wool-like nanocomposite (ECWN) is a novel synthetic bone substitute that incorporates amorphous calcium phosphate nanoparticles into a biodegradable synthetic copolymer poly(lactide-co-glycolide). The objectives of this study were to develop a tooth extraction socket model in sheep for bone graft research and to compare ECWN and bovine-derived xenograft (BX) in this model. Sixteen cross-bred female sheep were used. Bilateral mandibular premolars were extracted atraumatically. Second and third premolar sockets were filled (Latin-square allocation) with BX, ECWN or left unfilled. Resorbable collagen membranes were placed over BX and selected ECWN grafted sockets. Eight sheep per time period were sacrificed after 8 and 16 weeks. Resin-embedded undemineralised sections were analysed for descriptive histology and histomorphometric analyses. At 8 weeks, there were with no distinct differences in healing among the different sites. At 16 weeks, osseous healing followed a fine trabecular pattern in ECWN sites. Non-grafted sites showed thick trabeculae separated by large areas of fibrovascular connective tissue. In BX grafted sites, xenograft particles were surrounded by newly formed bone or fibrovascular connective tissue. There were no statistically significant differences in bone formation across the four groups. However, ECWN sites had significantly less residual graft material than BX sites at 16 weeks (P = 0.048). This first description of a tooth extraction socket model in sheep supports the utility of this model for bone graft research. The results of this study suggested that the novel material ECWN did not impede bone ingrowth into sockets and showed evidence of material resorption. © 2015 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

  4. Tissue reaction and material biodegradation of a calcium sulfate/apatite biphasic bone substitute in rat muscle

    Directory of Open Access Journals (Sweden)

    Jian-Sheng Wang

    2016-07-01

    Conclusion: Calcium sulfate hydroxyapatite bone substitute can be used as a carrier for antibiotics or other drugs, without adverse reaction due to the fast resorption of the calcium sulfate. No bone formation was seen despite treating the bone substitute with autologous bone marrow.

  5. Microstructure and biomechanical characteristics of bone substitutes for trauma and orthopaedic surgery

    NARCIS (Netherlands)

    E.M.M. van Lieshout (Esther); G.H. van Kralingen (Gerdine); Y. El-Massoudi (Youssef); H.H. Weinans (Harrie); P. Patka (Peter)

    2011-01-01

    textabstractAbstract. BACKGROUND: Many (artificial) bone substitute materials are currently available for use in orthopaedic trauma surgery. Objective data on their biological and biomechanical characteristics, which determine their clinical application, is mostly lacking. The aim of this study

  6. Bone regeneration and gene expression in bone defects under healthy and osteoporotic bone conditions using two commercially available bone graft substitutes.

    NARCIS (Netherlands)

    Houdt, C.I.A. van; Tim, C.R.; Crovace, M.C.; Zanotto, E.D.; Peitl, O.; Ulrich, D.J.O.; Jansen, J.A.; Parizotto, N.A.; Renno, A.C.; Beucken, J.J.J.P van den

    2015-01-01

    Biosilicate((R)) and Bio-Oss((R)) are two commercially available bone substitutes, however, little is known regarding their efficacy in osteoporotic conditions. The purpose of this study was to evaluate the osteogenic properties of both materials, at tissue and molecular level. Thirty-six Wistar

  7. Clinical Application of Antimicrobial Bone Graft Substitute in Osteomyelitis Treatment: A Systematic Review of Different Bone Graft Substitutes Available in Clinical Treatment of Osteomyelitis.

    Science.gov (United States)

    van Vugt, T A G; Geurts, J; Arts, J J

    2016-01-01

    Osteomyelitis is a common occurrence in orthopaedic surgery, which is caused by different bacteria. Treatment of osteomyelitis patients aims to eradicate infection by debridement surgery and local and systemic antibiotic therapy. Local treatment increases success rates and can be performed with different antimicrobial bone graft substitutes. This review is performed to assess the level of evidence of synthetic bone graft substitutes in osteomyelitis treatment. According to the PRISMA statement for reporting systematic reviews, different types of clinical studies concerning treatment of osteomyelitis with bone graft substitutes are included. These studies are assessed on their methodological quality as level of evidence and bias and their clinical outcomes as eradication of infection. In the fifteen included studies, the levels of evidence were weak and in ten out of the fifteen studies there was a moderate to high risk of bias. However, first results of the eradication of infection in these studies showed promising results with their relatively high success rates and low complication rates. Due to the low levels of evidence and high risks of bias of the included studies, these results are inconclusive and no conclusions regarding the performed clinical studies of osteomyelitis treatment with antimicrobial bone graft substitutes can be drawn.

  8. Bioactive behavior of silicon substituted calcium phosphate based bioceramics for bone regeneration.

    Science.gov (United States)

    Khan, Ather Farooq; Saleem, Muhammad; Afzal, Adeel; Ali, Asghar; Khan, Afsar; Khan, Abdur Rahman

    2014-02-01

    Bone graft substitutes are widely used for bone regeneration and repair in defect sites resulting from aging, disease, trauma, or accident. With invariably increasing clinical demands, there is an urgent need to produce artificial materials, which are readily available and are capable of fast and guided skeletal repair. Calcium phosphate based bioactive ceramics are extensively utilized in bone regeneration and repair applications. Silicon is often utilized as a substituent or a dopant in these bioceramics, since it significantly enhances the ultimate properties of conventional biomaterials such as surface chemical structure, mechanical strength, bioactivity, biocompatibility, etc. This article presents an overview of the silicon substituted bioceramics, which have emerged as efficient bone replacement and bone regeneration materials. Thus, the role of silicon in enhancing the biological performance and bone forming capabilities of conventional calcium phosphate based bioceramics is identified and reviewed.

  9. Efficacy of novel synthetic bone substitutes in the reconstruction of large segmental bone defects in sheep tibiae.

    Science.gov (United States)

    Li, Jiao Jiao; Roohani-Esfahani, Seyed-Iman; Dunstan, Colin R; Quach, Terrence; Steck, Roland; Saifzadeh, Siamak; Pivonka, Peter; Zreiqat, Hala

    2016-02-19

    The treatment of large bone defects, particularly those with segmental bone loss, remains a significant clinical challenge as current approaches involving surgery or bone grafting often do not yield satisfactory long-term outcomes. This study reports the evaluation of novel ceramic scaffolds applied as bone graft substitutes in a clinically relevant in vivo model. Baghdadite scaffolds, unmodified or modified with a polycaprolactone coating containing bioactive glass nanoparticles, were implanted into critical-sized segmental bone defects in sheep tibiae for 26 weeks. Radiographic, biomechanical, μ-CT and histological analyses showed that both unmodified and modified baghdadite scaffolds were able to withstand physiological loads at the defect site, and induced substantial bone formation in the absence of supplementation with cells or growth factors. Notably, all samples showed significant bridging of the critical-sized defect (average 80%) with evidence of bone infiltration and remodelling within the scaffold implant. The unmodified and modified baghdadite scaffolds achieved similar outcomes of defect repair, although the latter may have an initial mechanical advantage due to the nanocomposite coating. The baghdadite scaffolds evaluated in this study hold potential for use as purely synthetic bone graft substitutes in the treatment of large bone defects while circumventing the drawbacks of autografts and allografts.

  10. Histological Features and Biocompatibility of Bone and Soft Tissue Substitutes in the Atrophic Alveolar Ridge Reconstruction

    Directory of Open Access Journals (Sweden)

    Carlo Maiorana

    2016-01-01

    Full Text Available The reconstruction of the atrophic alveolar ridges for implant placement is today a common procedure in dentistry daily practice. The surgical reconstruction provides for the optimization of the supporting bone for the implants and a restoration of the amount of keratinized gingiva for esthetic and functional reasons. In the past, tissue regeneration has been performed with autogenous bone and free gingival or connective tissue grafts. Nowadays, bone substitutes and specific collagen matrix allow for a complete restoration of the atrophic ridge without invasive harvesting procedures. A maxillary reconstruction of an atrophic ridge by means of tissue substitutes and its histological features are then presented.

  11. Traumatic Periprosthetic Acetabular Fracture Treated with One-Stage Exchange and Bone Reconstruction Using a Synthetic Bone Graft Substitute

    Directory of Open Access Journals (Sweden)

    Jan Svacina

    2016-01-01

    Full Text Available A case of a traumatic periprosthetic acetabular fracture in an elderly patient, which was treated by one-stage hip exchange with implantation of an antiprotrusio cage and reconstruction of the acetabular bone loss with an injectable calcium sulphate/hydroxyapatite bone graft substitute, is reported. The paste-like bone graft substitute was injected through the holes of the antiprotrusio cage. After a setting time of 15 minutes, a low-profile cup was cemented onto the cage using polymethylmethacrylate and a new stem was inserted. The patient was encouraged to ambulate three days postoperatively weight-bearing as tolerated. At the one-year follow-up visit the patient was ambulatory and full weight-bearing without any walking aids. The follow-up radiographs demonstrated stable position and articulation of the revision hip arthroplasty with no signs of loosening of the antiprotrusio cage. However, the most interesting finding was that the bone graft substitute had remodelled to a great extent into bone. This calcium sulphate/hydroxyapatite composite shows high osteoconductive potential and can be used to regenerate bone stock in revision arthroplasty.

  12. Traumatic Periprosthetic Acetabular Fracture Treated with One-Stage Exchange and Bone Reconstruction Using a Synthetic Bone Graft Substitute.

    Science.gov (United States)

    Svacina, Jan

    2016-01-01

    A case of a traumatic periprosthetic acetabular fracture in an elderly patient, which was treated by one-stage hip exchange with implantation of an antiprotrusio cage and reconstruction of the acetabular bone loss with an injectable calcium sulphate/hydroxyapatite bone graft substitute, is reported. The paste-like bone graft substitute was injected through the holes of the antiprotrusio cage. After a setting time of 15 minutes, a low-profile cup was cemented onto the cage using polymethylmethacrylate and a new stem was inserted. The patient was encouraged to ambulate three days postoperatively weight-bearing as tolerated. At the one-year follow-up visit the patient was ambulatory and full weight-bearing without any walking aids. The follow-up radiographs demonstrated stable position and articulation of the revision hip arthroplasty with no signs of loosening of the antiprotrusio cage. However, the most interesting finding was that the bone graft substitute had remodelled to a great extent into bone. This calcium sulphate/hydroxyapatite composite shows high osteoconductive potential and can be used to regenerate bone stock in revision arthroplasty.

  13. Traumatic Periprosthetic Acetabular Fracture Treated with One-Stage Exchange and Bone Reconstruction Using a Synthetic Bone Graft Substitute

    Science.gov (United States)

    2016-01-01

    A case of a traumatic periprosthetic acetabular fracture in an elderly patient, which was treated by one-stage hip exchange with implantation of an antiprotrusio cage and reconstruction of the acetabular bone loss with an injectable calcium sulphate/hydroxyapatite bone graft substitute, is reported. The paste-like bone graft substitute was injected through the holes of the antiprotrusio cage. After a setting time of 15 minutes, a low-profile cup was cemented onto the cage using polymethylmethacrylate and a new stem was inserted. The patient was encouraged to ambulate three days postoperatively weight-bearing as tolerated. At the one-year follow-up visit the patient was ambulatory and full weight-bearing without any walking aids. The follow-up radiographs demonstrated stable position and articulation of the revision hip arthroplasty with no signs of loosening of the antiprotrusio cage. However, the most interesting finding was that the bone graft substitute had remodelled to a great extent into bone. This calcium sulphate/hydroxyapatite composite shows high osteoconductive potential and can be used to regenerate bone stock in revision arthroplasty. PMID:27446621

  14. Bone Substitutes for Peri-Implant Defects of Postextraction Implants

    Directory of Open Access Journals (Sweden)

    Pâmela Letícia Santos

    2013-01-01

    Full Text Available Placement of implants in fresh sockets is an alternative to try to reduce physiological resorption of alveolar ridge after tooth extraction. This surgery can be used to preserve the bone architecture and also accelerate the restorative procedure. However, the diastasis observed between bone and implant may influence osseointegration. So, autogenous bone graft and/or biomaterials have been used to fill this gap. Considering the importance of bone repair for treatment with implants placed immediately after tooth extraction, this study aimed to present a literature review about biomaterials surrounding immediate dental implants. The search included 56 articles published from 1969 to 2012. The results were based on data analysis and discussion. It was observed that implant fixation immediately after extraction is a reliable alternative to reduce the treatment length of prosthetic restoration. In general, the biomaterial should be used to increase bone/implant contact and enhance osseointegration.

  15. Effect of substitution of titanium by magnesium and niobium on structure and piezoelectric properties in (Bi1/2Na1/2)TiO3 ceramics

    Indian Academy of Sciences (India)

    Zhou Chang-Rong; Liu Xin-Yu; Li Wei-Zhou; Yuan Chang-Lai

    2011-12-01

    To develop new (Bi1/2Na1/2)TiO3-based ceramics with excellent piezoelectric properties, the similarities and the differences between PZT and (Bi1/2Na1/2)TiO3 ceramics were analysed. Based on the analysis, a new (Bi1/2Na1/2)TiO3-based piezoelectric ceramic of B-site substitution of complex ions (Mg1/3Nb2/3)4+ for Ti4+ was prepared by a conventional ceramic technique, and the effect of complex ions (Mg1/3Nb2/3)4+ addition on the microstructure, dielectric and piezoelectric properties was investigated. The research results show that all compositions are mono-perovskite phase and the grain size increases with increasing content of (Mg1/3Nb2/3)4+. The piezoelectric constant $d_{33}$ first increases and then decreases, and electromechanical coupling factor $k_{p}$ varies insignificantly with increasing content of (Mg1/3Nb2/3)4+.

  16. Effect of substitution of titanium by magnesium and niobium on structure and piezoelectric properties in (Bi1/2Na1/2)TiO3 ceramics

    Indian Academy of Sciences (India)

    Zhou Chang-Rong; Liu Xin-Yu; Li Wei-Zhou; Yuan Chang-Lai

    2009-02-01

    To develop new (Bi1/2Na1/2)TiO3-based ceramics with excellent piezoelectric properties, the similarities and the differences between PZT and (Bi1/2Na1/2)TiO3 ceramics were analysed. Based on the analysis, a new (Bi1/2Na1/2)TiO3-based piezoelectric ceramic of B-site substitution of complex ions (Mg1/3Nb2/3)4+ for Ti4+ was prepared by a conventional ceramic technique, and effect of complex ions (Mg1/3Nb2/3)4+ addition on the microstructure, dielectric and piezoelectric properties was investigated. The results show that all compositions are mono-perovskite phase and the grain size increases with increasing content of (Mg1/3Nb2/3)4+. The piezoelectric constant, 33, first increases and then decreases, and electromechanical coupling factor, p, varies insignificantly with increasing content of (Mg1/3Nb2/3)4+.

  17. Study on osteopotential activity of Terminalia arjuna bark extract incorporated bone substitute

    Indian Academy of Sciences (India)

    G Krithiga; T Hemalatha; R Deepachitra; Kausik Ghosh; T P Sastry

    2014-10-01

    Bark extract of Terminalia arjuna (TA) possesses potent medical properties and therefore, holds a reputed position in both Ayurvedic and Unani systems of medicine. Bone substitutes play an inevitable role in traumatic bone damages. Growth factors induce osteoinductivity, but suffer from limitations such as high cost and side effects. This study aims to evaluate the osteoinductive potential of bark extract of TA in bone substitutes. Bone substitutes prepared with TA bark extract were characterized for their physicochemical properties. In vitro biomineralization study was carried out using simulated body fluid. Cytotoxicity, alkaline phosphatase activity and mineralization potential were assessed using MG-63 cell lines. Scanning electron microscope revealed apatite formation on the surface after biomineralization. Thermogravimetric analysis showed 15% increase in residual weight by deposition of calcium and phosphate and their presence was identified by energy dispersive analysis. Increased alkaline phosphatase and calcium release was observed in bone substitutes prepared with TA extract compared with control. The functional groups of TA bark extract help in in vitro biomineralization. In MG-63 cells, it showed potential influence in cell differentiation. TA extract may be used as low-cost alternative for growth factors for treatment of fractured bones.

  18. Engineering bone tissue substitutes from human induced pluripotent stem cells

    National Research Council Canada - National Science Library

    Giuseppe Maria de Peppo; Iván Marcos-Campos; David John Kahler; Dana Alsalman; Linshan Shang; Gordana Vunjak-Novakovic; Darja Marolt

    2013-01-01

    ...) for bone tissue engineering. We first induced three hiPSC lines with different tissue and reprogramming backgrounds into the mesenchymal lineages and used a combination of differentiation assays, surface antigen profiling...

  19. A perfusion bioreactor system efficiently generates cell‐loaded bone substitute materials for addressing critical size bone defects

    Science.gov (United States)

    Kleinhans, Claudia; Mohan, Ramkumar Ramani; Vacun, Gabriele; Schwarz, Thomas; Haller, Barbara; Sun, Yang; Kahlig, Alexander; Kluger, Petra; Finne‐Wistrand, Anna; Walles, Heike

    2015-01-01

    Abstract Critical size bone defects and non‐union fractions are still challenging to treat. Cell‐loaded bone substitutes have shown improved bone ingrowth and bone formation. However, a lack of methods for homogenously colonizing scaffolds limits the maximum volume of bone grafts. Additionally, therapy robustness is impaired by heterogeneous cell populations after graft generation. Our aim was to establish a technology for generating grafts with a size of 10.5 mm in diameter and 25 mm of height, and thus for grafts suited for treatment of critical size bone defects. Therefore, a novel tailor‐made bioreactor system was developed, allowing standardized flow conditions in a porous poly(L‐lactide‐co‐caprolactone) material. Scaffolds were seeded with primary human mesenchymal stem cells derived from four different donors. In contrast to static experimental conditions, homogenous cell distributions were accomplished under dynamic culture. Additionally, culture in the bioreactor system allowed the induction of osteogenic lineage commitment after one week of culture without addition of soluble factors. This was demonstrated by quantitative analysis of calcification and gene expression markers related to osteogenic lineage. In conclusion, the novel bioreactor technology allows efficient and standardized conditions for generating bone substitutes that are suitable for the treatment of critical size defects in humans. PMID:26011163

  20. A perfusion bioreactor system efficiently generates cell-loaded bone substitute materials for addressing critical size bone defects.

    Science.gov (United States)

    Kleinhans, Claudia; Mohan, Ramkumar Ramani; Vacun, Gabriele; Schwarz, Thomas; Haller, Barbara; Sun, Yang; Kahlig, Alexander; Kluger, Petra; Finne-Wistrand, Anna; Walles, Heike; Hansmann, Jan

    2015-09-01

    Critical size bone defects and non-union fractions are still challenging to treat. Cell-loaded bone substitutes have shown improved bone ingrowth and bone formation. However, a lack of methods for homogenously colonizing scaffolds limits the maximum volume of bone grafts. Additionally, therapy robustness is impaired by heterogeneous cell populations after graft generation. Our aim was to establish a technology for generating grafts with a size of 10.5 mm in diameter and 25 mm of height, and thus for grafts suited for treatment of critical size bone defects. Therefore, a novel tailor-made bioreactor system was developed, allowing standardized flow conditions in a porous poly(L-lactide-co-caprolactone) material. Scaffolds were seeded with primary human mesenchymal stem cells derived from four different donors. In contrast to static experimental conditions, homogenous cell distributions were accomplished under dynamic culture. Additionally, culture in the bioreactor system allowed the induction of osteogenic lineage commitment after one week of culture without addition of soluble factors. This was demonstrated by quantitative analysis of calcification and gene expression markers related to osteogenic lineage. In conclusion, the novel bioreactor technology allows efficient and standardized conditions for generating bone substitutes that are suitable for the treatment of critical size defects in humans.

  1. Effects of Al substitution for Ca3Ta(Ga1-xAlx)3Si2O14 piezoelectric single crystals

    Science.gov (United States)

    Yokota, Yuui; Ohashi, Yuji; Kudo, Tetsuo; Kochurikhin, Vladimir V.; Medvedev, Andrey; Kurosawa, Shunsuke; Kamada, Kei; Yoshikawa, Akira

    2017-06-01

    Ca3Ta(Ga1-xAlx)3Si2O14 [CTGAS] material is a piezoelectric material belonging to the Langasite-type group (space group: P321).and the CTGAS single crystals (x=0, 0.25, 0.50, 0.75) with a diameter of 1 in. were grown by a Czochralski [Cz] method using an Ir crucible under Ar+2%O2. The CTGAS single crystals without any cracks could be grown using a CTGAS seed crystal in the x range of 0≤x≤0.75. Cell parameters, a and c, decrease while the a/c ratio increased with the Al concentration. Piezoelectric constant d11 and electromechanical coupling factor k12 for the X-cut specimens of the CTGAS single crystals were increased by the Al substitution.

  2. Effect of antimony substitution for niobium on the crystal structure, piezoelectric and dielectric properties of (K0.5Na0.5)NbO3 ceramics

    DEFF Research Database (Denmark)

    Mgbemere, H E; Schneider, G A; Stegk, Tobias

    2010-01-01

    The effect of antimony (Sb) substitution for niobium (Nb) on potassium sodium niobate (KNN) ceramic was investigated with respect to the densification behaviour at different sintering temperatures, microstructure and electrical properties. A small amount of Sb5+ was added while simultaneously...... lowering the amount of Nb5+ and in this study of the (K0.5Na0.5)(Nb1-xSbx)O3 system, x content was varied from 0 to 14 mol%. Our results show that Sb5+ slightly increased the optimum sintering temperature for KNN but above 8 mol%, its resistivity and piezoelectric properties decreased. As the amount of Sb5...... temperature. The dielectric loss slightly increases with increasing Sb5+ content up to 200°C. There was an improvement in the piezoelectric properties with ≤ 6 mol% Sb content while optimum properties were obtained with 4 mol% (KP = 0.46, Qm = 6.2, NP = 2296)....

  3. Sr-substituted bone cements direct mesenchymal stem cells, osteoblasts and osteoclasts fate

    Science.gov (United States)

    Panseri, Silvia; Dapporto, Massimiliano; Tampieri, Anna; Sprio, Simone

    2017-01-01

    Strontium-substituted apatitic bone cements enriched with sodium alginate were developed as a potential modulator of bone cells fate. The biological impact of the bone cement were investigated in vitro through the study of the effect of the nanostructured apatitic composition and the doping of strontium on mesenchymal stem cells, pre-osteoblasts and osteoclasts behaviours. Up to 14 days of culture the bone cells viability, proliferation, morphology and gene expression profiles were evaluated. The results showed that different concentrations of strontium were able to evoke a cell-specific response, in fact an inductive effect on mesenchymal stem cells differentiation and pre-osteoblasts proliferation and an inhibitory effect on osteoclasts activity were observed. Moreover, the apatitic structure of the cements provided a biomimetic environment suitable for bone cells growth. Therefore, the combination of biological features of this bone cement makes it as promising biomaterials for tissue regeneration. PMID:28196118

  4. Microtomographic and morphometric characterization of a bioceramic bone substitute in dental implantology

    Directory of Open Access Journals (Sweden)

    Deborah Meleo

    2012-01-01

    Full Text Available In recent years, bone tissue regeneration studies have led to a deeper knowledge of chemical and structural features of the best biomaterials to be used as replacements for lost bone structures, with the autologus bone still today the only graft material able to ostegenerate, osteinduct and/or osteoconduct. The difficulties of the small available amount of autologus bone, together with morbidity of a second surgical operation on the same patient, have been overcome using both synthetic and biologic substitute bones. The possibility of investigating morphometric characteristics of substitute bones makes it possible to evaluate the predictability of regenerative processes and, so far, a range of different methods have been used for the purpose. X-ray microtomography (micro-CT is a miniaturized form of conventional tomography, able to analyze the internal structure of small objects, performing three-dimensional images with high spatial resolution (<10 micron pixel size. For a correct analysis, samples need not be altered or treated in any way, as micro-CT is a non-invasive and non-destructive technique. It shows promising results in biomaterial studies and tissue engineering. This work shows the potential applications of this microtomographic technique by means of an in vitro analysis system, in characterizing morphometric features of human bone tissue, and contributes to the use of this technique in studies concerning biomaterials and bioscaffolds inserted in bone tissue.

  5. Hydroxyapatite-calcium sulfate-hyaluronic acid composite encapsulated with collagenase as bone substitute for alveolar bone regeneration.

    Science.gov (United States)

    Subramaniam, Sadhasivam; Fang, Yen-Hsin; Sivasubramanian, Savitha; Lin, Feng-Huei; Lin, Chun-pin

    2016-01-01

    Periodontitis is a very severe inflammatory condition of the periodontium that progressively damages the soft tissue and destroys the alveolar bone that supports the teeth. The bone loss is naturally irreversible because of limited reparability of the teeth. Advancement in tissue engineering provides an effective regeneration of osseous defects with suitable dental implants or tissue-engineered constructs. This study reports a hydroxyapatite, calcium sulfate hemihydrate and hyaluronic acid laden collagenase (HAP/CS/HA-Col) as a bone substitute for the alveolar bone regeneration. The composite material was mechanically tested and the biocompatibility was evaluated by WST-1 assay. The in vivo bone formation was assessed in rat with alveolar bone defects and the bone augmentation by the HAP/CS/HA-Col composite was confirmed by micro-CT images and histological examination. The mechanical strength of 6.69 MPa with excellent biocompatibility was obtained for the HAP/CS/HA-Col composite. The collagenase release profile had facilitated the acceleration of bone remodeling process and it was confirmed by the findings of micro-CT and H&E staining. The bone defects implanted with HAP/CS/HA composite containing 2 mg/mL type I collagenase have shown improved new bone formation with matured bone morphology in comparison with the HAP/CS/HA composite that lacks the collagenase and the porous hydroxyapatite (p-HAP) granules. The said findings demonstrated that the collagenase inclusion in HAP/CS/HA composite is a feasible approach for the alveolar bone regeneration and the same design can also be applied to other defective tissues.

  6. Mineralized polymer composites as biogenic bone substitute material

    Science.gov (United States)

    Shah, Rushita; Saha, Nabanita; Kitano, Takeshi; Saha, Petr

    2015-05-01

    Mineralized polymer composites (MPC) are recognized as potential fillers of bone defects. Though bioceramics exhibits quite a good bone-bonding and vascularization, it is considered to be too stiff and brittle for using alone. Thus, the use of polymer scaffold instead of bioceramics has several advantages including combining the osteoconductivity and bone-bonding potential of the inorganic phase with the porosity and interconnectivity of the three-dimensional construction. Aiming the advantages of ceramic-polymer composite scaffolds, the calcium carbonate (CaCO3) based biomineralized scaffold was prepared, where the PVP-CMC hydrogel was used as an extracellular matrix. This paper is reported about the morphology, swelling trend (in physiological solution) and viscoelastic behavior of (90 min mineralized) MPC. The dry MPC are off-white, coarse in texture, comparatively less flexible than the original PVP-CMC based hydrogel film, and the deposition of granular structures on the surface of the hydrogel film confirms about the development of biomineralized scaffold/polymer composites. Irrespective of thickness, the dry MPC shows higher values of swelling ratio within 30 min, which varies between 200-250 approximately. The dynamic viscoelastic nature of freshly prepared MPC was investigated applying 1% and 10% strain. At higher strain the viscoelastic moduli (G' and G") show significant change, and the nature of MPC turns from elastic to viscous. Based on the observed basic properties, the MPC (calcite based polymer composites) can be recommended for the treatment of adyanamic bone disorder.

  7. Pharmacokinetics of gentamicin eluted from a regenerating bone graft substitute

    DEFF Research Database (Denmark)

    Stravinskas, M; Horstmann, P; Ferguson, J;

    2016-01-01

    in patients treated surgically for chronic corticomedullary osteomyelitis. RESULTS: The release pattern in vitro was comparable with the obtained release in the patient studies. No recurrence was detected in the osteomyelitis group at latest follow-up (minimum 1.5 years). CONCLUSIONS: This new biphasic bone...

  8. Characterization of the inflammatory response to four commercial bone graft substitutes using a murine biocompatibility model

    Directory of Open Access Journals (Sweden)

    Markel DC

    2012-01-01

    Full Text Available David C Markel1, S Trent Guthrie2, Bin Wu3, Zheng Song4, Paul H Wooley41Department of Orthopaedics, Providence Hospital and Medical Centers, Southfield, MI, 2Henry Ford Hospital, Detroit, MI, 3Department of Biomedical Engineering, Wayne State University, Detroit, MI, 4Orthopaedic Research Institute, Wichita, KS, USAAbstract: Bone grafting is utilized in nearly all orthopedic subspecialties and in most anatomic regions. Bone graft substitutes have the potential to offer similar efficacy as autogenous grafts without the morbidity of harvest. Several studies have noted the efficacy of new-generation bone substitute products, but few studies have evaluated their safety. This study characterizes and quantifies the inflammatory reaction to four different commercially available bone graft substitutes, which were examined using the in vivo murine air pouch biocompatibility model. One coralline hydroxyapatite product was chosen as an example of a purely osteoconductive material. Three demineralized bone matrix products were chosen to represent products that are both osteoconductive and osteoinductive. Samples were implanted in a murine air pouch and harvested after 14 days in situ. Pouch fluid was extracted, mRNA isolated, and reverse transcription polymerase chain reactions carried out to detect interleukin-1 gene expression as a marker for inflammation. In addition, multiple histological characteristics were examined to quantify cellular responses to the implanted materials. All bone graft substitutes induced a significant inflammatory response compared with negative controls. Histology and polymerase chain reaction data indicated that the level of inflammatory reaction was elevated in materials with a higher demineralized bone matrix to carrier proportion. The hydroxyapatite product generated a low inflammatory reaction. In conclusion, this study used an in vivo model of biocompatibility to demonstrate that a significant inflammatory reaction occurs

  9. The effect of conventional surgery and piezoelectric surgery bone harvesting techniques on the donor site morbidity of the mandibular ramus and symphysis.

    Science.gov (United States)

    Altiparmak, N; Soydan, S S; Uckan, S

    2015-09-01

    The aim of this study was to evaluate the morbidity following bone harvesting at two different intraoral donor sites, mandibular symphysis and ramus, and to determine the effects of piezoelectric and conventional surgical graft harvesting techniques on donor site morbidity. Intraoral block bone grafts were harvested from the symphysis (n=44) and ramus (n=31). The two donor site groups were divided into two subgroups according to the surgical graft harvesting method used (conventional or piezoelectric surgery). Intraoperative and postoperative pain was assessed using a visual analogue scale (VAS). Donor site morbidity and the harvesting techniques were compared statistically. Of 290 teeth evaluated in the symphysis group, four needed root canal treatment after surgery. The incidence of transient paresthesia in the mucosa was significantly higher in the symphysis group than in the ramus group (P=0.004). In the symphysis group, the incidence of temporary skin and mucosa paresthesia was lower in the piezoelectric surgery subgroup than in the conventional surgery subgroup (P=0.006 and P=0.001, respectively). No permanent anaesthesia of any region of the skin was reported in either donor site group. VAS scores did not differ between the ramus and symphysis harvesting groups, or between the piezoelectric and conventional surgery subgroups. When the symphysis was chosen as the donor site, minor sensory disturbances of the mucosa and teeth were recorded. The use of piezoelectric surgery during intraoral harvesting of bone blocks, especially from the symphysis, can reduce these complications.

  10. New Bismuth-Substituted Hydroxyapatite Nanoparticles for Bone Tissue Engineering

    Science.gov (United States)

    Ciobanu, Gabriela; Bargan, Ana Maria; Luca, Constantin

    2015-11-01

    New bismuth-substituted hydroxyapatite [Ca10- x Bi x (PO4)6(OH)2 where x = 0-2.5] nanoparticles were synthesized by the co-precipitation method from aqueous solutions. The structural properties of the samples were analyzed by scanning electron microscopy coupled with x-ray analysis, x-ray powder diffraction, x-ray photoelectron spectroscopy, Fourier transform infrared spectroscopy and Brunauer-Emmett-Teller surface area analysis. The results confirm that bismuth ions have been incorporated into the hydroxyapatite lattice. The prepared nanocrystalline powders consisted of hydroxyapatite as single phase with hexagonal structure, crystal sizes smaller than 60 nm and (Bi + Ca)/P atomic ratio of around 1.67. The hydroxyapatite samples doped with Bi have mesoporous textures with pores size of around 2 nm and specific surface area in the range of 12-25 m2/g. The Bi-substituted hydroxyapatite powders are more effective against Gram-negative Escherichia coli bacteria than Gram-positive Staphylococcus aureus bacteria.

  11. Supercritical carbon dioxide-processed resorbable polymer nanocomposites for bone graft substitute applications

    Science.gov (United States)

    Baker, Kevin C.

    Numerous clinical situations necessitate the use of bone graft materials to enhance bone formation. While autologous and allogenic materials are considered the gold standards in the setting of fracture healing and spine fusion, their disadvantages, which include donor site morbidity and finite supply have stimulated research and development of novel bone graft substitute materials. Among the most promising candidate materials are resorbable polymers, composed of lactic and/or glycolic acid. While the characteristics of these materials, such as predictable degradation kinetics and biocompatibility, make them an excellent choice for bone graft substitute applications, they lack mechanical strength when synthesized with the requisite porous morphology. As such, porous resorbable polymers are often reinforced with filler materials. In the presented work, we describe the use of supercritical carbon dioxide (scCO2) processing to create porous resorbable polymeric constructs reinforced by nanostructured, organically modified Montmorillonite clay (nanoclay). scCO2 processing simultaneously disperses the nanoclay throughout the polymeric matrix, while imparting a porous morphology to the construct conducive to facilitating cellular infiltration and neoangiogenesis, which are necessary components of bone growth. With the addition of as little as 2.5wt% of nanoclay, the compressive strength of the constructs nearly doubles putting them on par with human cortico-cancellous bone. Rheological measurements indicate that the dominant mode of reinforcement of the nanocomposite constructs is the restriction of polymer chain mobility. This restriction is a function of the positive interaction between polymer chains and the nanoclay. In vivo inflammation studies indicate biocompatibility of the constructs. Ectopic osteogenesis assays have determined that the scCO2-processed nanocomposites are capable of supporting growth-factor induced bone formation. scCO 2-processed resorbable

  12. Bone graft substitutes and bone morphogenetic proteins for osteoporotic fractures: What is the evidence?

    NARCIS (Netherlands)

    E.M.M. van Lieshout (Esther); V. Alt (Volker)

    2016-01-01

    textabstractDespite improvements in implants and surgical techniques, osteoporotic fractures remain challenging to treat. Among other major risk factors, decreased expression of morphogenetic proteins has been identified for impaired fracture healing in osteoporosis. Bone grafts or bone graft

  13. Bone graft substitutes and bone morphogenetic proteins for osteoporotic fractures: What is the evidence?

    NARCIS (Netherlands)

    E.M.M. van Lieshout (Esther); V. Alt (Volker)

    2016-01-01

    textabstractDespite improvements in implants and surgical techniques, osteoporotic fractures remain challenging to treat. Among other major risk factors, decreased expression of morphogenetic proteins has been identified for impaired fracture healing in osteoporosis. Bone grafts or bone graft substi

  14. Injectable bone-graft substitutes: current products, their characteristics and indications, and new developments.

    Science.gov (United States)

    Larsson, Sune; Hannink, Gerjon

    2011-09-01

    More than a decade has passed since the first injectable bone substitutes were introduced for use in orthopaedic trauma, and over recent years the number of commercial products has increased dramatically. Despite the fact that these bone substitutes have been on the market for many years, knowledge amongst potential users on how and when they might be useful is still fairly limited. Most injectable bone substitutes belong to one of two major groups: by far the largest group contains products based on various calcium phosphate (CP) mixtures, whilst the smaller group consists of calcium sulphate (CS) compounds. Following mixing, the CP or CS paste can be injected into--for instance--a fracture space for augmentation as an alternative to bone graft, or around a screw for augmentation if the bone is weak. Within minutes an in situ process makes the substitute hard; the mechanical strength in compression resembles that of cancellous bone, whereas the strength in bending and shear is lower. Over time, CP products undergo remodelling through a cell-mediated process that seems to mimic the normal bone remodelling, whilst CS products are dissolved through a faster process that is not cell-mediated. For CP, a number of clinical studies have shown that it can be useful for augmentation of metaphyseal fractures when a space is present. Randomised studies have verified that CP works especially well in tibial plateau fractures when compared with conventional bone grafting. So far the number of clinical studies on CS products is very low. Development at present seems to be heading towards premixed or directly mixed products as well as new compounds that contain fibres or other components to enhance bending and shear strength. Products that are based on combinations of CP and CS are also being developed to combine the fast-dissolving CS with the stronger and more slowly remodelling CP. Injectable bone substitutes, and especially CS, have also been targeted as potentially good

  15. Injectability of brushite-forming Mg-substituted and Sr-substituted alpha-TCP bone cements.

    Science.gov (United States)

    Pina, S; Torres, P M C; Ferreira, J M F

    2010-02-01

    The influence of magnesium- and strontium-substitutions on injectability and mechanical performance of brushite-forming alpha-TCP cements has been evaluated in the present work. The effects of Mg- and Sr-substitutions on crystalline phase composition and lattice parameters were determined through quantitative X-ray phase analysis and structural Rietveld refinement of the starting calcium phosphate powders and of the hardened cements. A noticeable dependence of injectability on the liquid-to-powder ratio (LPR), smooth plots of extrusion force versus syringe plunger displacement and the absence of filter pressing effects were observed. For LPR values up to 0.36 ml g(-1), the percentage of injectability was always higher and lower for Mg-containing cements and for Sr-containing cements, respectively, while all the pastes could be fully injected for LPR > 0.36 ml g(-1). The hardened cements exhibited relatively high wet compressive strength values (~17-25 MPa) being the Sr- and Mg-containing cements the strongest and the weakest, respectively, holding an interesting promise for uses in trauma surgery such as for filling bone defects and in minimally invasive techniques such as percutaneous vertebroplasty to fill lesions and strengthen the osteoporotic bone.

  16. Bone Substitute Fabrication Based on Dissolution-Precipitation Reactions

    Directory of Open Access Journals (Sweden)

    Kunio Ishikawa

    2010-02-01

    Full Text Available Although block- or granular-type sintered hydroxyapatite are known to show excellent tissue responses and good osteoconductivity, apatite powder elicits inflammatory response. For the fabrication of hydroxyapatite block or granules, sintering is commonly employed. However, the inorganic component of bone and tooth is not high crystalline hydroxyapatite but low crystalline B-type carbonate apatite. Unfortunately, carbonate apatite powder cannot be sintered due to its instability at high temperature. Another method to fabricate apatite block and/or granule is through phase transformation based on dissolution-precipitation reactions using a precursor phase. This reaction basically is the same as a setting and hardening reaction of calcium sulfate or plaster. In this paper, apatite block fabrication methods by phase transformation based on dissolution-precipitation reactions will be discussed, with a focus on the similarity of the setting and hardening reaction of calcium sulfate.

  17. Directly auto-transplanted mesenchymal stem cells induce bone formation in a ceramic bone substitute in an ectopic sheep model

    Science.gov (United States)

    Boos, Anja M; Loew, Johanna S; Deschler, Gloria; Arkudas, Andreas; Bleiziffer, Oliver; Gulle, Heinz; Dragu, Adrian; Kneser, Ulrich; Horch, Raymund E; Beier, Justus P

    2011-01-01

    Abstract Bone tissue engineering approaches increasingly focus on the use of mesenchymal stem cells (MSC). In most animal transplantation models MSC are isolated and expanded before auto cell transplantation which might be critical for clinical application in the future. Hence this study compares the potential of directly auto-transplanted versus in vitro expanded MSC with or without bone morphogenetic protein-2 (BMP-2) to induce bone formation in a large volume ceramic bone substitute in the sheep model. MSC were isolated from bone marrow aspirates and directly auto-transplanted or expanded in vitro and characterized using fluorescence activated cell sorting (FACS) and RT-PCR analysis before subcutaneous implantation in combination with BMP-2 and β-tricalcium phosphate/hydroxyapatite (β-TCP/HA) granules. Constructs were explanted after 1 to 12 weeks followed by histological and RT-PCR evaluation. Sheep MSC were CD29+, CD44+ and CD166+ after selection by Ficoll gradient centrifugation, while directly auto-transplanted MSC-populations expressed CD29 and CD166 at lower levels. Both, directly auto-transplanted and expanded MSC, were constantly proliferating and had a decreasing apoptosis over time in vivo. Directly auto-transplanted MSC led to de novo bone formation in a heterotopic sheep model using a β-TCP/HA matrix comparable to the application of 60 μg/ml BMP-2 only or implantation of expanded MSC. Bone matrix proteins were up-regulated in constructs following direct auto-transplantation and in expanded MSC as well as in BMP-2 constructs. Up-regulation was detected using immunohistology methods and RT-PCR. Dense vascularization was demonstrated by CD31 immunohistology staining in all three groups. Ectopic bone could be generated using directly auto-transplanted or expanded MSC with β-TCP/HA granules alone. Hence BMP-2 stimulation might become dispensable in the future, thus providing an attractive, clinically feasible approach to bone tissue engineering. PMID

  18. Dual mode antibacterial activity of ion substituted calcium phosphate nanocarriers for bone infections

    Directory of Open Access Journals (Sweden)

    Sampath Kumar eT.S.

    2015-05-01

    Full Text Available Nanotechnology has tremendous potential for the management of infectious diseases caused by multi-drug resistant (MDR bacteria, through the development of newer antibacterial materials and efficient modes of antibiotic delivery. Calcium phosphate (CaP bioceramics are commonly used as bone substitutes due to their similarity to bone mineral and are widely researched upon for the treatment of bone infections associated with bone loss. CaPs can be used as local antibiotic delivery agents for bone infections and can be substituted with antibacterial ions in their crystal structure to have a wide spectrum, sustained antibacterial activity even against drug resistant bacteria. In the present work, a dual mode antibiotic delivery system with antibacterial ion substituted calcium deficient hydroxyapatite (CDHA nanoparticles has been developed. Antibacterial ions such as zinc, silver and strontium have been incorporated into CDHA at concentrations of 6 at. %, 0.25-0.75 at. % and 2.5-7.5 at. % respectively. The samples were found to be phase pure, acicular nanoparticles of length 40-50 nm and width 5-6 nm approximately. The loading and release profile of doxycycline, a commonly used antibiotic, was studied from the nanocarriers. The drug release was studied for five days and the release profile was influenced by the ion concentrations. The release of antibacterial ions was studied over a period of 21 days. The ion substituted CDHA samples were tested for antibacterial efficacy on S.aureus and E.coli by MIC/MBC studies and time-kill assay. AgCDHA and ZnCDHA showed high antibacterial activity against both bacteria while SrCDHA was weakly active against S.aureus. Present study shows that the antibiotic release can provide the initial high antibacterial activity and the sustained ion release can provide a long-term antibacterial activity. Such dual mode antibiotic and antibacterial ion release offers an efficient and potent way to treat an incumbent drug

  19. Tusk or Bone? An Example of Ivory Substitute in the Wildlife Trade

    Directory of Open Access Journals (Sweden)

    Margaret E. Sims

    2011-08-01

    Full Text Available Bone carvings (and other ivory substitutes are common in the modern-day lucrative international ivory trade.  Souvenirs for unknowing travelers and market shoppers can be made of non-biological material (plastic "ivory" beads or skillfully crafted natural objects made to resemble something other than their true origin.  Many of these items are received at the U. S. National Fish and Wildlife Forensics Laboratory (NFWFL for species identification as part of law enforcement investigations.  Morphologists at the Lab often receive uniquely carved ivory items that have been imported with little or no documentation.  In recent years, analysts examined several purported ivory tusks suspected to be walrus, a protected marine mammal.  After examination, the Lab determined their origin as carved leg bones of cattle using principles and methods of zooarchaeology and ancient DNA analysis.  The naturally long and straight ungulate metapodials had been cut, carved, filled, stained, and polished to closely resemble unmodified ivory tusks.  Morphological species identification of these bones proved to be a challenge since diagnostic characters of the bones had been altered and country of origin was unknown. Genetic analysis showed that the bones originated from cattle.  While bone is commonly used as a substitute for ivory, this style of artifact was not previously documented in the wildlife trade prior to our analysis.  Archaeological ethnobiologists commonly encounter bone tools and other forms of material culture from prehistoric and historic contexts; in this case bone tools come from a modern context, thus the application of methods common in zooarchaeology are situated in wildlife forensics.  In addition, results reported here pertain to cross-cultural ivory trade and conservation science.

  20. Substituted Borosilicate Glasses with Improved Osteogenic Capacity for Bone Tissue Engineering.

    Science.gov (United States)

    Fernandes, João S; Gentile, Piergiorgio; Crawford, Aileen; Pires, Ricardo A; Hatton, Paul V; Reis, Rui L

    2017-03-27

    Borosilicate bioactive glasses (BBGs) have shown the capacity to promote higher formation of new bone when compared with silicate bioactive glasses. Herein, we assessed the capacity of BBGs to induce osteogenic differentiation of bone marrow mesenchymal stem cells (BM-MSCs) as a function of their substituted divalent cations (Mg(2+), Ca(2+), Sr(2+)). To this purpose, we synthesized BBG particles by melt quenching. The cell viability, proliferation, and morphology (i.e., PrestoBlue(®), PicoGreen(®), and DAPI and Phalloidin stainings, respectively), as well as protein expression (i.e., alkaline phosphatase, ALP; osteopontin, OP; and osteocalcin, OC), of BM-MSCs in contact with BBGs were evaluated for 21 days. We observed an enhanced expression of bone-specific proteins (ALP, OP, and OC) and high mineralization of BM-MSCs under BBG-Mg and BBG-Sr-conditioned osteogenic media for concentrations of 20 and 50 mg/mL with low cytotoxic effects. Moreover, BBG-Sr, at a concentration of 50 mg/mL, was able to increase the mineralization and expression of the same bone-specific proteins even under basal medium conditions. These results indicated that the proposed BBGs improved osteogenic differentiation of BM-MSCs, therefore showing their potential as relevant biomaterials for bone tissue regeneration, not only by bonding to bone tissue but also by stimulating new bone formation.

  1. Composite Based Chitosan/Zinc-Doped HA as a Candidate Material for Bone Substitute Applications

    Science.gov (United States)

    Wicaksono, S. T.; Rasyida, A.; Purnomo, A.; Pradita, N. N.; Ardhyananta, H.; Hidayat, M. I. P.

    2017-05-01

    The composite based Zinc-doped in Chitosan/Hydroxyapatite was successfully prepared by wet mixing method through the addition of 10, 15, and 20wt% of chitosan. The addition of Chitosan increased the compressive strength and the modulus elasticity. However, it decreased the density and the surface hardness of HA-Zn. Mechanical characterization revealed that these composites are suitable as a candidate of a cancellous bone substitute. Composite with 10% chitosan has compressive strength and modulus elasticity of 57.03 MPa and 0.15 GPa, respectively. Hence, it has the physical and mechanical properties that meet the standards as a cancellous bone substitute material. Also, in vitro biocompatibility test against BHK-21 cells exhibited non-toxic materials.

  2. Evaluation of injectable silica-embedded nanohydroxyapatite bone substitute in a rat tibia defect model

    Directory of Open Access Journals (Sweden)

    Xu W

    2011-08-01

    Full Text Available Weiguo Xu1, Cornelia Ganz2, Ulf Weber2, Martin Adam2, Gerd Holzhüter2, Daniel Wolter3, Bernhard Frerich3, Brigitte Vollmar1, Thomas Gerber21Institute for Experimental Surgery, 2Institute of Physics, 3Department of Oral, Maxillofacial and Plastic Surgery, University of Rostock, Rostock, GermanyAbstract: In clinical practice, vertebral compression fractures occur after trauma and osteoporosis. Kyphoplasty is a minimally invasive procedure using bone filler material for the treatment of such fractures. A full synthetic injectable bone substitute (SIBS was manufactured by means of spray drying. The aim of this study was to characterize the SIBS and to analyze the remodelling process during degradation of the biomaterial and new bone formation after implantation. SIBS is an aqueous suspension of donut-like microparticles. These microparticles consist of nanocrystallites of synthetic hydroxyapatite embedded in amorphous silica gel. After implantation of SIBS in a proximal tibial diaphyseal defect in 52 rats, grafts were harvested for subsequent analysis on different days. Newly formed bone originating from endosteum was observed on day 6. Hematomas in the medullary space and cortical wounds disappeared on day 12. The wound region was completely replaced by a composite of newly formed cancellous bone, extracellular matrix, and SIBS. At day 63 the cortical defect was fully healed by bone, while newly formed bone in the medullary space almost disappeared and was replaced with bone marrow. In conclusion, SIBS demonstrated a unique structure with osteoinductive and bioresorbable properties, which induced fast bone regeneration. Therefore, a clinical application of SIBS for kyphoplasty is promising.Keywords: bone remodelling, electron microscopy, histomorphometry, nanotechnology, tissue engineering

  3. Cell response of calcium phosphate based ceramics, a bone substitute material

    Directory of Open Access Journals (Sweden)

    Juliana Marchi

    2013-01-01

    Full Text Available The aim of this study was to characterize calcium phosphate ceramics with different Ca/P ratios and evaluate cell response of these materials for use as a bone substitute. Bioceramics consisting of mixtures of hydroxyapatite (HAp and β-tricalcium phosphate (β-TCP powders in different proportions were pressed and sintered. The physical and chemical properties of these bioceramics were then characterized. Characterization of the biological properties of these materials was based on analysis of cell response using cultured fibroblasts. The number of cells attached to the samples was counted from SEM images of samples exposed to cell culture solution for different periods. These data were compared by analysis of variance (ANOVA complemented by the Tukey's test. The TCP sample had higher surface roughness and lower density. The adherence and growth of FMM1 cells on samples from all groups was studied. Even though the different calcium based ceramics exhibited properties which made them suitable as bone substitutes, those with higher levels of β-TCP revealed improved cell growth on their surfaces. These observations indicated two-phase calcium phosphate based materials with a β-TCP surface layer to be a promising bone substitute.

  4. Paracrystalline Disorder from Phosphate Ion Orientation and Substitution in Synthetic Bone Mineral

    Energy Technology Data Exchange (ETDEWEB)

    Marisa, Mary E.; Zhou, Shiliang; Melot, Brent C.; Peaslee, Graham F.; Neilson, James R.

    2016-12-05

    Hydroxyapatite is an inorganic mineral closely resembling the mineral phase in bone. However, as a biological mineral, it is highly disordered, and its composition and atomistic structure remain poorly understood. Here, synchrotron X-ray total scattering and pair distribution function analysis methods provide insight into the nature of atomistic disorder in a synthetic bone mineral analogue, chemically substituted hydroxyapatite. By varying the effective hydrolysis rate and/or carbonate concentration during growth of the mineral, compounds with varied degrees of paracrystallinity are prepared. From advanced simulations constrained by the experimental pair distribution function and density functional theory, the paracrystalline disorder prevalent in these materials appears to result from accommodation of carbonate in the lattice through random displacement of the phosphate groups. Though many substitution modalities are likely to occur in concert, the most predominant substitution places carbonate into the mirror plane of an ideal phosphate site. Understanding the mineralogical imperfections of a biologically analogous hydroxyapatite is important not only to potential bone grafting applications but also to biological mineralization processes themselves.

  5. Development of multi-substituted hydroxyapatite nanopowders as biomedical materials for bone tissue engineering applications.

    Science.gov (United States)

    Baba Ismail, Yanny M; Wimpenny, Ian; Bretcanu, Oana; Dalgarno, Kenneth; El Haj, Alicia J

    2017-02-15

    Ionic substitutions have been proposed as a tool to control the functional behavior of synthetic hydroxyapatite (HA), particularly for Bone Tissue Engineering (BTE) applications. The effect of simultaneous substitution of different levels of carbonate (CO3 ) and silicon (Si) ions in the HA lattice was investigated. Furthermore, human bone marrow-derived mesenchymal stem cells (hMSCs) were cultured on multi-substituted HA (SiCHA) to determine if biomimetic chemical compositions were osteoconductive. Of the four different compositions investigates, SiCHA-1 (0.58wt% Si) and SiCHA-2 (0.45wt% Si) showed missing bands for CO3 and Si using FTIR analysis, indicating competition for occupation of the phosphate site in the HA lattice. 500°C was considered the most favourable calcination temperature as: (i) the powders produced possessed a similar amount of CO3 (2-8wt%) and Si (<1.0wt%) as present in native bone; and (ii) there was a minimal loss of CO3 and Si from the HA structure to the surroundings during calcination. Higher Si content in SiCHA-1 led to lower cell viability and at most hindered proliferation, but no toxicity effect occurred. While, lower Si content in SiCHA-2 showed the highest ALP/DNA ratio after 21 days culture with hMSCs, indicating that the powder may stimulate osteogenic behaviour to a greater extent than other powders. This article is protected by copyright. All rights reserved.

  6. A modified rabbit ulna defect model for evaluating periosteal substitutes in bone engineering: a pilot study

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    Rania M El Backly

    2015-01-01

    Full Text Available The present work defines a modified critical size rabbit ulna defect model for bone regeneration in which a non-resorbable barrier membrane was used to separate the radius from the ulna to create a valid model for evaluation of tissue-engineered periosteal substitutes. Eight rabbits divided into two groups were used. Critical defects (15 mm were made in the ulna completely eliminating periosteum. For group I, defects were filled with a nanohydroxyapatite poly(ester urethane scaffold soaked in PBS and left as such (group Ia or wrapped with a tissue-engineered periosteal substitute (group Ib. For group II, an e-PTFE (GORE-TEX® membrane was inserted around the radius then the defects received either scaffold alone (group IIa or scaffold wrapped with periosteal substitute (group IIb. Animals were euthanized after 12-16 weeks, and bone regeneration was evaluated by radiography, computed microtomography (µCT, and histology. In the first group, we observed formation of radio-ulnar synostosis irrespective of the treatment. This was completely eliminated upon placement of the e-PTFE (GORE-TEX® membrane in the second group of animals. In conclusion, modification of the model using a non-resorbable e-PTFE membrane to isolate the ulna from the radius was a valuable addition allowing for objective evaluation of the tissue-engineered periosteal substitute.

  7. Effects of Sr2+substitution on the structural, dielectric, and piezoelectric properties of PZT-PMN ceramics

    Institute of Scientific and Technical Information of China (English)

    Arvind Kumar; S.K. Mishra

    2014-01-01

    This study described the structural, dielectric, and piezoelectric behavior of Pb1-xSrx[(Zr0.52Ti0.48)0.95(Mn1/3Nb2/3)0.05]O3 ceramics (PSZT-PMN, x=0, 0.025, 0.050, and 0.075), prepared by a semi-wet route. X-ray diffraction, dielectric, and piezoelectric investigations were carried out to analyze the crystal structure. The relative dielectric constant and dielectric loss were both calculated as the functions of temperature. The room-temperature dielectric constant reaches a maximum for a Sr2+-modified PZT-PMN ceramic with an x value of 0.050, which corresponds to the morphotropic phase boundary (MPB). Raman spectroscopy studies also confirm the existence of this MPB for x=0.050. The piezoelectric strain coefficients (d33) value shows a maximum response for this composition. In addition, the phase transition temperature decreases significantly when the Sr2+concentration increases in the PZT-PMN ceramics.

  8. Calcium phosphate cements for bone substitution: chemistry, handling and mechanical properties.

    Science.gov (United States)

    Zhang, Jingtao; Liu, Weizhen; Schnitzler, Verena; Tancret, Franck; Bouler, Jean-Michel

    2014-03-01

    Since their initial formulation in the 1980s, calcium phosphate cements (CPCs) have been increasingly used as bone substitutes. This article provides an overview on the chemistry, kinetics of setting and handling properties (setting time, cohesion and injectability) of CPCs for bone substitution, with a focus on their mechanical properties. Many processing parameters, such as particle size, composition of cement reactants and additives, can be adjusted to control the setting process of CPCs, concomitantly influencing their handling and mechanical performance. Moreover, this review shows that, although the mechanical strength of CPCs is generally low, it is not a critical issue for their application for bone repair--an observation not often realized by researchers and clinicians. CPCs with compressive strengths comparable to those of cortical bones can be produced through densification and/or homogenization of the cement matrix. The real limitation for CPCs appears to be their low fracture toughness and poor mechanical reliability (Weibull modulus), which have so far been only rarely studied.

  9. Three-Dimensional Assessment of Volumetric Changes in Sinuses Augmented with Two Different Bone Substitutes

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    B. Alper Gultekin

    2016-01-01

    Full Text Available Introduction. The bone volume of the posterior maxilla may not be appropriate for implant placement, due to factors such as pneumatized maxillary sinus. The purpose of this study was to evaluate the percentage of graft volume reduction following sinus floor elevation (SFE, with either slow resorbable bone substitute only or a composite of slow and fast resorbable bone substitutes, using cone beam computed tomography (CBCT. Materials and Methods. In this retrospective study, CBCT scans of SFE procedures were evaluated to determine the volume of grafted sinus with either deproteinized bovine bone (DBB or a 2 : 1 mixture of biphasic calcium sulfate (CS and DBB, as a composite. The volumetric changes of sinus augmentations were measured 2 weeks (V-I and 6 months (V-II after operation. Results. Thirty-three patients were included in this study. The average percentage volume reduction was 9.39±3.01% and 17.65±4.15% for DBB and composite grafts, respectively. A significant graft volume reduction was observed between V-I and V-II for both groups (p<0.01. The DBB group exhibited significantly less volume reduction than the composite group (p<0.01. Conclusions. Augmented sinus volume may change before implant placement. DBB offers greater volume stability during healing than composite grafts.

  10. Intraosseous focal venous malformation of the mandibular body: Cone beam computed tomography planning followed by piezoelectric knife resection and free bone graft reconstruction

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    Nikolić Živorad S.

    2017-01-01

    Full Text Available Introduction. Intraosseous vascular malformation could be life-threatening due to uncontrolled hemorrhage after tooth extraction. According to biological behavior of this lesion, adequate diagnostic and treatment strategies are necessary in order to avoid possible complications. We reported cone beam computed tomography (CBCT planning of an urgent en bloc resection of an intraosseous venous malformation by piezoelectric knife. Case report. A 55-year-old man was submitted to CBCT planning followed by piezoelectric knife resection of an intraosseous focal venous malformation of the mandibular body. Immediate reconstruction of the defect using iliac bone free graft was performed. The surgical treatment was uneventful and a 2-year follow-up revealed no signs of recurrence. Conclusion. Piezoelectric knife could provide precise, safe and bloodless procedure which is especially important in this pathology. Advantages of this technique are: lower risk of damaging soft tissue structures, precise osteotomy and bloodless surgery. Moreover, using piezosurgery bone knife, blood transfusion and blood transmitted diseases could be avoided. This case highlights the importance of CBCT as planning tool for resection of the mandible, using piezoelectric knife as safe method to achieve bloodless surgery. [Project of the Serbian Ministry of Education, Science and Technological Development, Grant no. 175075

  11. Mandibular Bone and Soft Tissues Necrosis Caused by an Arsenical Endodontic Preparation Treated with Piezoelectric Device

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    A. Giudice

    2013-01-01

    Full Text Available This paper describes a case of wide mandibular bone necrosis associated with significant soft tissues injury after using an arsenical endodontic preparation in the right lower second molar for endodontic purpose. Authors debate about the hazardous effects of the arsenic paste and the usefulness of piezosurgery for treatment of this drug related bone necrosis.

  12. Histological comparison of an allograft, a xenograft and alloplastic graft as bone substitute materials

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    C.E. Nappe

    2016-11-01

    Full Text Available Aim An allograft, a xenograft and an alloplastic graft, associated to sinus lift or ridge preservation procedures were histologically studied to evaluate their characteristics and to obtain the percentages of bone and remaining graft particles. This may help the clinician to determine, form the histological point of view, if they are viable alternatives to the use of autograft in bone regeneration procedures. Materials and methods Twenty-five samples from 18 subjects were histologically evaluated with respect to newly formed bone and remaining graft particles percentage. Results The three studied grafting materials presented adequate osteoconduction characteristics. Differences in newly formed bone percentage were found between the allograft and the xenograft, whereas no differences were found between the allograft and the alloplastic graft or the xenograft and the alloplastic graft. There were no significant differences in the percentage of residual particles amongst the different types of graft. Conclusions All studied bone substitute materials showed good characteristics for their use in bone regeneration therapies.

  13. A novel calcium phosphate ceramic-magnetic nanoparticle composite as a potential bone substitute.

    Science.gov (United States)

    Wu, Yao; Jiang, Wen; Wen, Xiantao; He, Bin; Zeng, Xiaobo; Wang, Gang; Gu, Zhongwei

    2010-02-01

    A magnetic field has been applied to accelerate bone healing for a long time. In this study, in order to combine the bone repair capability of calcium phosphate (CaP) ceramics with the magnetic field, a novel CaP ceramic-magnetic nanoparticle (CaP-MNP) composite was fabricated through integrating the superparamagnetic nanoparticles into the CaP ceramics. Two kinds of CaP ceramics were chosen: hydroxyapatite (HA) and HA/tricalcium phosphate (65/35, HT). The samples were cultured with Ros17/2.8 and MG63 cells respectively in vitro to evaluate the cell proliferation and differentiation via MTT and alkaline phosphatase activity tests. In order to find the influence of the magnetic materials on the expression of the bone morphological protein (BMP), the samples composited with BMP-2 were implanted subcutaneously in the fasciae of rat back muscles for 30 days. Compared with ordinary CaP ceramics, the results indicated that the CaP-MNP composite had good biocompatibility and was able to promote cell proliferation and differentiation significantly. The in vivo test showed that the expression of BMP-2 would be accelerated by HT composited with MNPs, and new bone-like tissue formation could be observed. Accordingly, it might be expected that this CaP-MNP composite could become a potential bone substitute or bone tissue engineering scaffold.

  14. Bone substitute biomedical material of multi-(amino acid) copolymer: in vitro degradation and biocompatibility.

    Science.gov (United States)

    Li, Hong; Yan, Yonggang; Wei, Jie; Ma, Jian; Gong, Min; Luo, Xiaoman; Zhang, Yunfei

    2011-11-01

    Degradable polymers with good mechanical strength as bone repair biomaterials have been paid more attention in biomedical application. In this study, a multi-(amino acid) copolymer consisting of 6-aminocaproic acid and five natural amino acids was prepared by a reaction of acid-catalyzed condensation. The results revealed that the copolymer could be slowly degradable in Tris-HCl solution, and lost its initial weight of 31.9 wt% after immersion for 12 weeks, and the changes of pH value of Tris-HCl solution were in range from 6.9 to 7.4 during soaking. The compressive strength of the copolymer decreased from 107 to 68 MPa after immersion for 12 weeks. The proliferation and differentiation of MG-63 cells on the copolymer significantly increased with time, and the cells with normal phenotype extended and spread well on the copolymer surfaces. When the copolymer was implanted in muscle and bone defects of femoral cortex of dogs for 12 weeks, the histological evaluation confirmed that the copolymer exhibited excellent biocompatibility and more effective osteogenesis in vivo. When implanted into cortical bone defects of dogs, the copolymer could be combined directly with the natural bone without fibrous capsule tissue between implants and host bone. The results indicated that the multi-(amino acid) copolymer with sufficient strength, good biocompatibility and osteoconductivity had clinical potential for load-bearing bone repair or substitution.

  15. Collagen immobilization of multi-layered BCP-ZrO{sub 2} bone substitutes to enhance bone formation

    Energy Technology Data Exchange (ETDEWEB)

    Linh, Nguyen Thuy Ba [Department of Regenerative Medicine, College of Medicine, Soonchunhyang University, Cheonan, 330-090 (Korea, Republic of); Institute of Tissue Regeneration, College of Medicine, Soonchunhyang University, Cheonan, 330-090 (Korea, Republic of); Jang, Dong-Woo [Department of Regenerative Medicine, College of Medicine, Soonchunhyang University, Cheonan, 330-090 (Korea, Republic of); Lee, Byong-Taek, E-mail: lbt@sch.ac.kr [Department of Regenerative Medicine, College of Medicine, Soonchunhyang University, Cheonan, 330-090 (Korea, Republic of); Institute of Tissue Regeneration, College of Medicine, Soonchunhyang University, Cheonan, 330-090 (Korea, Republic of)

    2015-08-01

    Graphical abstract: - Highlights: • Col-BCP-ZrO. • Collagen fibers were formed and attached firmly on the surface of BCP-ZrO. • Highly interconnected but uniform porosity were obtained. • High biocompatible, strength scaffolds and new bone were evident in Col-BCP-ZrO{sub 2}. - Abstract: A porous microstructure of multi-layered BCP-ZrO{sub 2} bone substitutes was fabricated using the sponge replica method in which the highly interconnected structure was immobilized with collagen via ethyl(dimethylaminopropyl)carbodiimide/N-hydroxysuccinimide crosslinking. Their struts are combined with a three-layered BCP/BCP-ZrO{sub 2}/ZrO{sub 2} microstructure. Collagen fibers were firmly attached to the strut surface of the BCP-ZrO{sub 2} scaffolds. With control of the three-layered microstructure and collagen immobilization, the compressive strength of the scaffolds increased significantly to 6.8 MPa compared to that of the monolithic BCP scaffolds (1.3 MPa). An in vitro study using MTT, confocal observation, and real-time polymer chain reaction analysis demonstrated that the proliferation and differentiation of the pre-osteoblast-like MC3T3-E1 cells was improved due to the collagen incorporation. Remarkable enhancement of bone regeneration was observed without any immunological reaction in the femurs of rabbits during 1 and 5 months of implantation. Furthermore, the interfaces between new bone and the scaffold struts bonded directly without any gaps.

  16. Performance of broilers fed with snail (Pomacea caniculata meal as substitute to fish meal or meat and bone meal

    Directory of Open Access Journals (Sweden)

    Ulep, LJL.

    1991-01-01

    Full Text Available Snail meal was used as a substitution to fish meat and bone meal in broiler rations. Final weightand feed conversion efficiency of the birds, profit and return on investment differed significantly among treatments. Feed consumption and production costs were comparable. Results show that snail meal can replace fish or meat and bone meal in broiler diets.

  17. Brushite-Forming Mg-, Zn- and Sr-Substituted Bone Cements for Clinical Applications

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    José M.F. Ferreira

    2010-01-01

    Full Text Available Calcium phosphate cements have been in clinical use for the last 10 years. Their most salient features include good biocompatibility, excellent bioactivity, self-setting characteristics, low setting temperature, adequate stiffness, and easy shaping to accomodate any complicated geometry. They are commonly used in filling bone defects and trauma surgeries as mouldable paste-like bone substitute materials. Substitution of trace elements, such as Mg, Sr and Zn ions, into the structure of calcium phosphates is the subject of widespread investigation nowadays, because of their impending role in the biological process. Subtle differences in composition and structure of these materials may have a profound effect on their in vivo behaviour. Therefore, the main goal of this paper is to provide a simple, but comprehensive overview of the present achievements relating to brushite-forming cements doped with Mg, Zn and Sr, and to identify new developments and trends. In particular, the influence of ionic substitution on the chemical, physical and biological properties of these materials is discussed.

  18. Immunohistochemical characterization of wound healing at two different bone graft substitutes.

    Science.gov (United States)

    Sager, M; Ferrari, D; Wieland, M; Dard, M; Becker, J; Schwarz, F

    2012-05-01

    The immunohistochemical characteristics of wound healing following application of a biphasic calcium phosphate or a collagen coated natural bone combined with a native collagen membrane in a dog model was assessed. Standardized buccal dehiscence-type defects were surgically created following implant bed preparation in 6 dogs. Following implant placement, defects were randomly filled with a collagen coated natural bone mineral (GBO), or a biphasic hydroxyapatite/beta tricalcium phosphate (SBC), and covered with a native collagen membrane. After 1, 4, and 9 weeks' submerged healing, dissected blocks were processed for immunohistochemical (collagen type I (CI), osteocalcin (OC), angiogenesis (TG)) analysis. At 1 week, GBO and SBC granules were homogeneously surrounded by a well vascularized, non-mineralized tissue (NMT). CI and OC antigen reactivity was commonly observed adjacent to both bone graft substitutes. At 4 and 9 weeks, SBC and GBO granules were completely integrated into a secondly formed network of spongiosa. At 9 weeks, dissolution of some granules was observed in the SBC group. Adjacent to these granules, NMT was significantly increased and revealed a pronounced CI, OC and TG antigen reactivity. The initial pattern of bone regeneration and graft integration was comparable in both groups; bone remodelling was more pronounced with SBC.

  19. Morphological and mechanical characterization of chitosan-calcium phosphate composites for potential application as bone-graft substitutes

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    Guilherme Maia Mulder van de Graaf

    Full Text Available Introduction: Bone diseases, aging and traumas can cause bone loss and lead to bone defects. Treatment of bone defects is challenging, requiring chirurgical procedures. Bone grafts are widely used for bone replacement, but they are limited and expensive. Due to bone graft limitations, natural, semi-synthetic, synthetic and composite materials have been studied as potential bone-graft substitutes. Desirable characteristics of bone-graft substitutes are high osteoinductive and angiogenic potentials, biological safety, biodegradability, bone-like mechanical properties, and reasonable cost. Herein, we prepared and characterized potential bone-graft substitutes composed of calcium phosphate (CP - a component of natural bone, and chitosan (CS - a biocompatible biopolymer. Methods CP-CS composites were synthetized, molded, dried and characterized. The effect of drying temperatures (38 and 60 °C on the morphology, porosity and chemical composition of the composites was evaluated. As well, the effects of drying temperature and period of drying (3, 24, 48 and 72 hours on the mechanical properties - compressive strength, modulus of elasticity and relative deformation-of the demolded samples were investigated. Results Scanning electron microscopy and gas adsorption-desorption analyses of the CS-CP composites showed interconnected pores, indicating that the drying temperature played an important role on pores size and distribution. In addition, drying temperature have altered the color (brownish at 60 °C due to Maillard reaction and the chemical composition of the samples, confirmed by FTIR. Conclusion Particularly, prolonged period of drying have improved mechanical properties of the CS-CP composites dried at 38 °C, which can be designed according to the mechanical needs of the replaceable bone.

  20. Development and characterization of novel alginate-based hydrogels as vehicles for bone substitutes.

    Science.gov (United States)

    Morais, D S; Rodrigues, M A; Silva, T I; Lopes, M A; Santos, M; Santos, J D; Botelho, C M

    2013-06-05

    In this work three different hydrogels were developed to associate, as vehicles, with the synthetic bone substitute GR-HAP. One based on an alginate matrix (Alg); a second on a mixture of alginate and chitosan (Alg/Ch); and a third on alginate and hyaluronate (Alg/HA), using Ca(2+) ions as cross-linking agents. The hydrogels, as well as the respective injectable bone substitutes (IBSs), were fully characterized from the physical-chemical point of view. Weight change studies proved that all hydrogels were able to swell and degrade within 72 h at pH 7.4 and 4.0, being Alg/HA the hydrogel with the highest degradation rate (80%). Rheology studies demonstrated that all hydrogels are non-Newtonian viscoelastic fluids, and injectability tests showed that IBSs presented low maximum extrusion forces, as well as quite stable average forces. In conclusion, the studied hydrogels present the necessary features to be successfully used as vehicles of GR-HAP, particularly the hydrogel Alg/HA.

  1. The Role of Resorbable Plate and Artificial Bone Substitute in Reconstruction of Large Orbital Floor Defect

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    Ho Kwon

    2016-01-01

    Full Text Available It is essential to reduce and reconstruct bony defects adequately in large orbital floor fracture and defect. Among many reconstructive methods, alloplastic materials have attracted attention because of their safety and ease of use. We have used resorbable plates combined with artificial bone substitutes in large orbital floor defect reconstructions and have evaluated their long-term reliability compared with porous polyethylene plate. A total of 147 patients with traumatic orbital floor fracture were included in the study. Surgical results were evaluated by clinical evaluations, exophthalmometry, and computed tomography at least 12 months postoperatively. Both orbital floor height discrepancy and orbital volume change were calculated and compared with preoperative CT findings. The average volume discrepancy and vertical height discrepancies were not different between two groups. Also, exophthalmometric measurements were not significantly different between the two groups. No significant postoperative complication including permanent diplopia, proptosis, and enophthalmos was noted. Use of a resorbable plate with an artificial bone substitute to repair orbital floor defects larger than 2.5 cm2 in size yielded long-lasting, effective reconstruction without significant complications. We therefore propose our approach as an effective alternative method for large orbital floor reconstructions.

  2. Bioactive glass incorporation in calcium phosphate cement-based injectable bone substitute for improved in vitro biocompatibility and in vivo bone regeneration.

    Science.gov (United States)

    Sadiasa, Alexander; Sarkar, Swapan Kumar; Franco, Rose Ann; Min, Young Ki; Lee, Byong Taek

    2014-01-01

    In this work, we fabricated injectable bone substitutes modified with the addition of bioactive glass powders synthesized via ultrasonic energy-assisted hydrothermal method to the calcium phosphate-based bone cement to improve its biocompatibility. The injectable bone substitutes was initially composed of a powder component (tetracalcium phosphate, dicalcium phosphate dihydrate and calcium sulfate dehydrate) and a liquid component (citric acid, chitosan and hydroxyl-propyl-methyl-cellulose) upon which various concentrations of bioactive glass were added: 0%, 10%, 20% and 30%. Setting time and compressive strength of the injectable bone substitutes were evaluated and observed to improve with the increase of bioactive glass content. Surface morphologies were observed via scanning electron microscope before and after submersion of the samples to simulated body fluid and increase in apatite formation was detected using x-ray diffraction machine. In vitro biocompatibility of the injectable bone substitutes was observed to improve with the addition of bioactive glass as the proliferation/adhesion behavior of cells on the material increased. Human gene markers were successfully expressed using real time-polymerase chain reaction and the samples were found to promote cell viability and be more biocompatible as the concentration of bioactive glass increases. In vivo biocompatibility of the samples containing 0% and 30% bioactive glass were evaluated using Micro-CT and histological staining after 3 months of implantation in male rabbits' femurs. No inflammatory reaction was observed and significant bone formation was promoted by the addition of bioactive glass to the injectable bone substitute system.

  3. Effect of Fe and Fe-Ba substitution on the piezoelectric and dielectric properties of lead zirconate titanate ceramics

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    Sangawar, S.R., E-mail: sudhirsangawar85@gmail.com [PZT Centre, Armament Research and Development Establishment, Pune 411021 (India); Praveenkumar, B.; Kumar, H.H.; Kharat, D.K. [PZT Centre, Armament Research and Development Establishment, Pune 411021 (India)

    2011-02-25

    Polycrystalline samples of Fe and Fe-Ba doped lead zirconate titanate (PZT) ceramics near the morphotrophic phase boundary have been synthesized by a solid-state reaction technique. Preliminary X-ray analysis of the compound confirms that there is no change in the crystal structure of PZT on co-doping with Fe and Ba. The maximum mechanical quality factor Q{sub m} was found to be 1000 for Fe doped material and 880 for Fe-Ba doped material. The electromechanical coupling factor for Fe and Fe-Ba doped samples were 0.535 and 0.495 respectively. The corresponding values for the piezoelectric charge constant d{sub 33} were 135 and 250 pC/N respectively. These results are discussed in terms of position occupied by dopants in to the lattice and their corresponding microstructures. These Fe-Ba doped PZT materials could be likely candidates for high power ultrasonic and underwater SONAR transducer systems.

  4. Effects of zinc-substituted nano-hydroxyapatite coatings on bone integration with implant surfaces

    Institute of Scientific and Technical Information of China (English)

    Shi-fang ZHAO; Wen-jing DONG; Qiao-hong JIANG; Fu-ming HE; Xiao-xiang WANG; Guo-li YANG

    2013-01-01

    Objective:The purpose of this study was to investigate the effects of a zinc-substituted nano-hydroxyapatite (Zn-HA) coating,applied by an electrochemical process,on implant osseointegraton in a rabbit model.Methods:A Zn-HA coating or an HA coating was deposited using an electrochemical process.Surface morphology was examined using field-emission scanning electron microscopy.The crystal structure and chemical composition of the coatings were examined using an X-ray diffractometer (XRD) and Fourier transform infrared spectroscopy (FTIR).A total of 78 implants were inserted into femurs and tibias of rabbits.After two,four,and eight weeks,femurs and tibias were retrieved and prepared for histomorphometric evaluation and removal torque (RTQ) tests.Results:Rod-like HA crystals appeared on both implant surfaces.The dimensions of the Zn-HA crystals seemed to be smaller than those of HA.XRD patterns showed that the peaks of both coatings matched well with standard HA patterns.FTIR spectra showed that both coatings consisted of HA crystals.The Zn-HA coating significantly improved the bone area within all threads after four and eight weeks (P<0.05),the bone to implant contact (BIC) at four weeks (P<0.05),and RTQ values after four and eight weeks (P<0.05).Conclusions:The study showed that an electrochemically deposited Zn-HA coating has potential for improving bone integration with an implant surface.

  5. Design and optimization of a tissue-engineered bone graft substitute

    Science.gov (United States)

    Shimko, Daniel Andrew

    2004-12-01

    formulation, and scaffold material from all preceding studies were combined and a tissue-engineered bone graft was fabricated. The graft was exposed to long-term in vitro culture, and then mechanically evaluated to determine its clinical potential. The studies contained herein constitute the first steps in the conception and development of a viable tissue-engineered bone graft substitute and establish a solid scientific foundation for future in vivo experimentation utilizing this design.

  6. Effect of Lanthanum Substitution on the Structural, dielectric, Ferroelectric and Piezoelectric Properties of Mechanically Activated PZt Electroceramics

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    Ajeet Kumar

    2016-06-01

    Full Text Available Different compositions of (Pb1-xLax (Zr0.60Ti0.40O3 (abbreviated as PLZT x/60/40; x=0, 0.07, 0.08 and 0.10 ceramics were prepared by a combinatorial approach by high energy mechano-chemical ball milling and cold isostatic pressing (CIP. X-ray diffraction patterns and transmission as well as scanning electron microscope were used for the micro-structural and morphological studies. The average particle size of PLZT milled powders was measured from the TEM images and was found to be in the nm range.XRD patterns of the sintered PLZT x/60/40 ceramics confirm the perovskite phase formation after heat treatment. SEM of sintered PLZT x/60/40 ceramics show a close packed dense structure. PLZT 8/60/40 ceramics show the fine grains (~1.3 µm with density ~97 per cent. Dielectric constant and loss were measured as a function of temperature. PLZT 8/60/40 ceramics shows the highest value of room temperature dielectric constant ~2480 at 1 kHz. Ferroelectric studies were done with the help of polarisation (P-E and strain (S-E vs. electric field measurements. PLZT 8/60/40 ceramics shows the maximum value of remnant polarisation (~36 µC/cm2 and strain (~0.27 per cent, respectively. PLZT x/60/40 ceramic samples were poled at optimized poling conditions. The measured values of piezoelectric charge coefficient (d33 and electromechanical coupling factor (kp of PLZT 8/60/40 ceramics were found to be, ~690 pC/N and ~71 per cent, respectively.

  7. Design, synthesis, and initial evaluation of D-glyceraldehyde crosslinked gelatin-hydroxyapatite as a potential bone graft substitute material

    Science.gov (United States)

    Florschutz, Anthony Vatroslav

    Utilization of bone grafts for the treatment of skeletal pathology is a common practice in orthopaedic, craniomaxillofacial, dental, and plastic surgery. Autogenous bone graft is the established archetype but has disadvantages including donor site morbidity, limited supply, and prolonging operative time. In order to avoid these and other issues, bone graft substitute materials are becoming increasingly prevalent among surgeons for reconstructing skeletal defects and arthrodesis applications. Bone graft substitutes are biomaterials, biologics, and guided tissue/bone regenerative devices that can be used alone or in combinations as supplements or alternatives to autogenous bone graft. There is a growing interest and trend to specialize graft substitutes for specific indications and although there is good rationale for this indication-specific approach, the development and utility of a more universal bone graft substitute may provide a better answer for patients and surgeons. The aim of the present research focuses on the design, synthesis, and initial evaluation of D-glyceraldehyde crosslinked gelatin-hydroxyapatite composites for potential use as a bone graft substitutes. After initial establishment of rational material design, gelatinhydroxyapatite scaffolds were fabricated with different gelatin:hydroxyapatite ratios and crosslinking concentrations. The synthesized scaffolds were subsequently evaluated on the basis of their swelling behavior, porosity, density, percent composition, mechanical properties, and morphology and further assessed with respect to cell-biomaterial interaction and biomineralization in vitro. Although none of the materials achieved mechanical properties suitable for structural graft applications, a reproducible material design and synthesis was achieved with properties recognized to facilitate bone formation. Select scaffold formulations as well as a subset of scaffolds loaded with recombinant human bone morphogenetic protein-2 were

  8. Implantation of silicon dioxide-based nanocrystalline hydroxyapatite and pure phase beta-tricalciumphosphate bone substitute granules in caprine muscle tissue does not induce new bone formation

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    Ghanaati Shahram

    2013-01-01

    Full Text Available Abstract Background Osteoinductive bone substitutes are defined by their ability to induce new bone formation even at heterotopic implantation sites. The present study was designed to analyze the potential osteoinductivity of two different bone substitute materials in caprine muscle tissue. Materials and methods One gram each of either a porous beta-tricalcium phosphate (β-TCP or an hydroxyapatite/silicon dioxide (HA/SiO2-based nanocrystalline bone substitute material was implanted in several muscle pouches of goats. The biomaterials were explanted at 29, 91 and 181 days after implantation. Conventional histology and special histochemical stains were performed to detect osteoblast precursor cells as well as mineralized and unmineralized bone matrix. Results Both materials underwent cellular degradation in which tartrate-resistant acid phosphatase (TRAP-positive osteoclast-like cells and TRAP-negative multinucleated giant cells were involved. The ß-TCP was completely resorbed within the observation period, whereas some granules of the HA-groups were still detectable after 180 days. Neither osteoblasts, osteoblast precursor cells nor extracellular bone matrix were found within the implantation bed of any of the analyzed biomaterials at any of the observed time points. Conclusions This study showed that ß-TCP underwent a faster degradation than the HA-based material. The lack of osteoinductivity for both materials might be due to their granular shape, as osteoinductivity in goat muscle has been mainly attributed to cylindrical or disc-shaped bone substitute materials. This hypothesis however requires further investigation to systematically analyze various materials with comparable characteristics in the same experimental setting.

  9. Conversion of sea urchin spines to Mg-substituted tricalcium phosphate for bone implants.

    Science.gov (United States)

    Vecchio, Kenneth S; Zhang, Xing; Massie, Jennifer B; Wang, Mark; Kim, Choll W

    2007-09-01

    The skeleton of sea urchin spines is composed of large single crystals of Mg-rich calcite, which have smooth, continuously curved surfaces and form a three-dimensional fenestrated mineral network. Spines of the echinoids Heterocentrotus trigonarius and Heterocentrotus mammillatus were converted by the hydrothermal reaction at 180 degrees C to bioresorbable Mg-substituted tricalcium phosphate (beta-TCMP). Due to the presence of Mg in the calcite lattice, conversion to beta-TCMP occurs preferentially to hydroxyapatite formation. The converted beta-TCMP still maintains the three-dimensional interconnected porous structures of the original spine. The main conversion mechanism is the ion-exchange reaction, although there is also a dissolution-reprecipitation process that forms some calcium phosphate precipitates on the surfaces of the spine network. The average fracture strength of urchin spines and converted spines (beta-TCMP) in the compression tests are 42 and 23MPa, respectively. In vivo studies using a rat model demonstrated new bone growth up to and around the beta-TCMP implants after implantation in rat femoral defects for 6 weeks. Some new bone was found to migrate through the spine structural pores, starting from the outside of the implant through the pores at the edge of the implants. These results indicate good bioactivity and osteoconductivity of the porous beta-TCMP implants.

  10. Hydroxyapatite reinforced with multi-walled carbon nanotubes and bovine serum albumin for bone substitute applications

    Science.gov (United States)

    Gholami, Fatemeh; Noor, Ahmad-Fauzi Mohd

    2016-12-01

    The similarity of the chemical composition of HA to the mineral phase of bone and its excellent biocompatibility meets the requirement of materials designed for bone substitute purpose. The application of HA in load bearing devices is limited by its poor mechanical properties. CNTs with outstanding stiffness, strength, combined with their small size and large interfacial area, suggest that they may have great potential as a reinforcing agent for HA. This work aims to develop the Hydroxyapatite/Multi-walled Carbon Nanotubes/Bovine Serum Albumin (HA/MWCNTs/BSA) composites with different types of MWCNTs including hydroxylated and carboxylated MWCNTs (MWCNTs-OH, MWCNTs-COOH), and evaluation of mechanical strength and in vitro cellular response of developed composites. HA powder was mixed with de-ionized water, 15 wt.% BSA, and 0.5 wt.% of different MWCNTs* (> 95%), MWCNTs (> 99.9%), MWCNTs-OH (> 99.9%), MWCNTs-COOH (> 99.9%) to produce composites. Among all developed composites, the HA/MWCNTs-COOH/BSA shows the highest compressive strength (29.57 MPa). The cytotoxic effect of HA/MWCNTs-COOH/BSA with different concentrations (6.25 to 200 µg/ml) was evaluated by MTT assay against normal human colon fibroblast (CCD-18Co cell line). At low concentration, all developed composites were found to be non-cytotoxic when treated to the human fibroblast cells and did not elicit cytotoxic effects on cell proliferation and the highest values of cell viability (283%) for the HA/MWCNTs-COOH/BSA composites obtained; whereas when the concentration was increased, the reduction in cell viability was observed. The novel composites showed favorable cytocompatibility with improved compressive strength which make it applicable to use in range of trabecular bone.

  11. Probing the intrapore surface of phenyl-substituted nanoscale mesoporous silica-piezoelectric sorption measurements in thin films.

    Science.gov (United States)

    Darga, Alexander; Kecht, Johann; Bein, Thomas

    2007-12-18

    The incorporation of organic moieties into siliceous frameworks leads to a wide variety of adsorbate-adsorbent interactions including weak van-der-Waal attractions as well as strong interactions such as Coulomb forces. Depending on the desired properties of such substituted highly porous matrix materials, optimized synthesis routes can be established to enhance the desired internal pore surface-affinity toward certain volatile compounds. On the basis of a fundamental knowledge of the host-guest system, sorption-related applications may benefit from individually fine-tuned and modified sample materials. The sorption isotherms of vaporized toluene on nonmodified and phenyl-functionalized mesoporous silica samples were determined on an acoustic wave device at different temperatures. The mesoporous silica was modified by in situ co-condensation and postsynthesis grafting approaches, respectively. All samples were thoroughly characterized by nitrogen sorption, thermogravimetric analysis (TGA), scanning and transmission electron microscopy (SEM, TEM), solid-state nuclear magnetic resonance (29Si NMR), dynamic light scattering (DLS), Raman spectroscopy, and toluene adsorption on a quartz crystal microbalance (QCM). The different heats of adsorption of toluene on the various modified silica surfaces obtained by the sorption data make it possible to gain additional information about the degree and type of surface functionalization. It is thus demonstrated that QCM studies can be a powerful and convenient tool for efficient investigations of functionalized mesoporous silica particles that yield valuable quantitative information on molecule-surface interactions.

  12. Structural evaluation and animal implantation of porous eggshell wastederived hydroxyapatite graft as bone substitution

    Directory of Open Access Journals (Sweden)

    Yudha Mathan Sakti Rahadyan Magetsari

    2014-08-01

    Full Text Available The development of hydroxyapatite graft with high economically value is needed for orthopedic practice in developing countries. Eggsell waste is well known as natural substance for calcium resource. It has been used as raw material in producing hydroxyapatite. This study was conducted to synthesize porous hydroxyapatite from eggshell waste and evaluate its activity as bone substitution. The porous hydroxyapatite graft was manufactured from eggshell and sugar as a raw material using hydrothermal process. The porous eggshell waste-derived hydroxyapatite (EW-HAP graft was characterized using X ray difractometer (XRD and analytical scanning electron microscope (SEM and compared with commercial hydroxyapatite (HAP JCPDS 09-432 graft (Bangros® as standard. The porous EW-HAP graft obtained was then implanted on critically sized femoral defects surgically created in the right thigh of male Wistar rats (Rattus norvegicus with Bangros® as control. Radiological examination using XRD and histological examination using hematoxyline-and-eosin staining of the bone femour were performed at 28 days after implantation. The results showed that the XRD pattern for EW-HAP was likely similar with the HAP standard. However, the SEM examination showed that the pasticle size of EW-HAP graft (2.5-3 μm was higher than those HAP standard graft (1.5-2 μm. Radiographs according to the International of Limb Salvage (ISOLS radiological evaluation system between EW-HAP graft (6.1 ± 1.45 and HAP control graft (6.9 ± 2.10 was not significantly different (p>0.05. Moreover, histological examination according to Lane and Shandu scoring system between the both graft (4.0 ± 0.94 versus 4.4 ± 0.92 was also not significantly different (p>0.05. It can be concluded that the structure EW-HAP graft is similar with HAP graft standard. The both grafts have also equal outcome as bone substitution.

  13. Analysis of Impingement between Patella Bone and Bearing Post in Cruciate-Substituting High-Flexion Total Knee Arthroplasty.

    Science.gov (United States)

    Chon, Jegyun; Lee, Bongju; Shin, Sangyeop; Jang, Gunil; Jeon, Taehyeon

    2016-06-01

    We investigated the causes of impingement between the patella bone and the bearing post during high flexion in cruciate-substituting total knee arthroplasty and proposed a treatment strategy. This prospective cohort study included 218 cases that had undergone cruciate-substituting total knee arthroplasty from February 2014 to January 2015; a single surgeon performed the operation using the same method without patellar resurfacing in all patients. In these patients, the occurrence of impingement was determined by performing more than 120° high knee flexion after inserting a bearing perioperatively. The incidence of impingement was significantly associated with bearing design, femoral implant size, patella bone length, and patella inferior pole angle (p patella bone. In the cruciate-substituting high-flexion total knee arthroplasty, impingement between the patella bone and bearing post was more common in patients with mobile bearing, small-size femoral component, and a long patella or a large inferior pole angle. In cases of intraoperative impingement between the patella bone and the bearing post, resection in the lower portion of the patella prevented impingement of the bearing with soft tissue or the patella by widening the space between the patella and the bearing post, which in turn prevented postoperative reduction in range of motion.

  14. Preclinical investigation of an innovative magnesium-based bone graft substitute for potential orthopaedic applications

    Directory of Open Access Journals (Sweden)

    Chen Liu

    2014-07-01

    Full Text Available Degradable or corrosive biometal is an attractive research and development (R&D area in clinical orthopaedics. This study was designed to investigate biomechanical and biological properties of magnesium (Mg and strontium (Sr with a focus on Mg-based metals, including pure Mg and Mg–xwt% Sr (x = 0.25, x = 1.0, x = 1.5, x = 2.5 alloys, as potential bone graft substitutes in respect to their mechanical strength, corrosion resistance, and cytocompatibility for further optimization and establishing indications for relevant in vivo applications. Our data showed that the tensile and compressive strength increased with addition of Sr because of the Mg17Sr2 precipitation strengthen. Compared with commercially used bone graft substitutes, the mechanical properties of Mg–Sr alloys were close to those of cortical bone, and the compressive strength could reach 300 MPa, suggesting its potential application for load-bearing bone as bone defect filler. The corrosion rates of Mg–xwt% Sr alloys were controlled in the range of 0.05–0.07 mm/y, indicating feasibility of bone grafting and the in situ bone repair process. Moreover, Mg–Sr alloys also exhibit good cytocompatibility and antibacterial properties. Our innovation presented in this work supported in vivo clinical indication-based assessment of biodegradable Mg-based metals that could be potential candidates for bone graft substitutes for future orthopaedic applications.

  15. Fibrin gel-immobilized primary osteoblasts in calcium phosphate bone cement: in vivo evaluation with regard to application as injectable biological bone substitute.

    Science.gov (United States)

    Kneser, U; Voogd, A; Ohnolz, J; Buettner, O; Stangenberg, L; Zhang, Y H; Stark, G B; Schaefer, D J

    2005-01-01

    Osteogenic injectable bone substitutes may be useful for many applications. We developed a novel injectable bone substitute based on osteoblast-fibrin glue suspension and calcium phosphate bone cement (BC). Human osteoblasts were isolated from trabecular bone samples and cultured under standard conditions. Osteoblasts were suspended in fibrinogen solution (FS). BC was cured with thrombin solution. 8 x 4 mm injectable bone discs were prepared using silicon molds and a custom-made applicator device. Discs containing BC, BC/FS, or BC/FS/osteoblasts were implanted subcutaneously into athymic nude mice. After 3, 9 and 24 weeks, specimens were explanted and subjected to morphologic and biomechanical evaluation. In vitro fibrin gel-embedded osteoblasts displayed a differentiated phenotype as evidenced by alkaline phosphatase, collagen type 1 and von Kossa stains. A proportion of osteoblasts appeared morphologically intact over a 3-day in vitro period following application into the BC. BC/FS and BC/FS/osteoblast discs were sparsely infiltrated with vascularized connective tissue. There was no bone formation in implants from all groups. However, positive von Kossa staining only in BC/FS/osteoblast groups suggests engraftment of at least some of the transplanted cells. Biomechanical evaluation demonstrated initial stability of the composites. Young's modulus and maximal load did not differ significantly in the BC/FS and BC/FS/osteoblast groups. The practicability of osteoblast-containing injectable bone could be demonstrated. The dense microstructure and the suboptimal initial vascularization of the composites may explain the lack of bone formation. Modifications with regard to enhanced osteoblast survival are mandatory for a possible application as injectable osteogenic bone replacement system.

  16. Evaluation of hydroxyapatite and beta-tricalcium phosphate mixed with bone marrow aspirate as a bone graft substitute for posterolateral spinal fusion

    Directory of Open Access Journals (Sweden)

    Bansal Sanjay

    2009-01-01

    Full Text Available Background: Autologous cancellous bone is the most effective biological graft material. However, harvest of autologous bone is associated with significant morbidity. Since porous hydroxyapatite and beta-tricalcium phosphate are biodegradable materials and can be replaced by bone tissue, but it lacks osteogenic property. We conducted a study to assess their use as a scaffold and combine them with bone marrow aspirate for bone regeneration using its osteogenic property for posterolateral spinal fusion on one side and autologous bone graft on the other side and compare them radiologically in terms of graft incorporation and fusion. Materials and Methods: Thirty patients with unstable dorsal and lumbar spinal injuries who needed posterior stabilization and fusion were evaluated in this prospective study from October 2005 to March 2008. The posterior stabilization was done using pedicle screw and rod assembly, and fusion was done using hydroxyapatite and beta-tricalcium phosphate mixed with bone marrow aspirate as a bone graft substitute over one side of spine and autologous bone graft obtained from iliac crest over other side of spine. The patients were followed up to a minimum of 12 months. Serial radiographs were done at an interval of 3, 6, and 12 months and CT scan was done at one year follow-up. Graft incorporation and fusion were assessed at each follow-up. The study was subjected to statistical analysis using chi-square and kappa test to assess graft incorporation and fusion. Results: At the end of the study, radiological graft incorporation and fusion was evident in all the patients on the bone graft substitute side and in 29 patients on the autologous bone graft side of the spine ( P > 0.05. One patient showed lucency and breakage of distal pedicle screw in autologous bone graft side. The interobserver agreement (kappa had an average of 0.72 for graft incorporation, 0.75 for fusion on radiographs, and 0.88 for the CT scan findings

  17. Calcite as a bone substitute. Comparison with hydroxyapatite and tricalcium phosphate with regard to the osteoblastic activity

    Energy Technology Data Exchange (ETDEWEB)

    Monchau, F., E-mail: Francine.monchau@univ-artois.fr [Laboratoire Genie Civil et geo-Environnement (EA 4515, Universite Lille Nord de France), Equipe Biomateriaux Artois (Universite d' Artois), IUT/GMP, 1230, rue de l' Universite, BP 819, 62408 Bethune cedex (France); Hivart, Ph.; Genestie, B. [Laboratoire Genie Civil et geo-Environnement (EA 4515, Universite Lille Nord de France), Equipe Biomateriaux Artois (Universite d' Artois), IUT/GMP, 1230, rue de l' Universite, BP 819, 62408 Bethune cedex (France); Chai, F. [Laboratoire Medicaments et Biomateriaux a Liberation Controlee (INSERM U 1008, Universite Lille Nord de France), Groupe de Recherche sur les Biomateriaux (Universite Lille-2), Faculte de Medecine, 1, place de Verdun, 59045 Lille cedex (France); and others

    2013-01-01

    Close to the bone mineral phase, the calcic bioceramics, such as hydroxyapatite (HA) and {beta}-tricalcium phosphate ({beta}-TCP), are commonly used as substitutes or filling materials in bone surgery. Besides, calcium carbonate (CaCO{sub 3}) is also used for their excellent biocompatibility and bioactivity. However, the problem with the animal-origin aragonite demands the new technique to synthesize pure calcite capable of forming 3D bone implant. This study aims to manufacture and evaluate a highly-pure synthetic crystalline calcite with good cytocompatibility regarding to the osteoblasts, comparing to that of HA and {beta}-TCP. After the manufacture of macroporous bioceramic scaffolds with the identical internal architecture, their cytocompatibility is studied through MC3T3-E1 osteoblasts with the tests of cell viability, proliferation, vitality, etc. The results confirmed that the studied process is able to form a macroporous material with a controlled internal architecture, and this synthesized calcite is non-cytotoxic and facilitate the cell proliferation. Indeed requiring further improvement, the studied calcite is definitely an interesting alternative not only to coralline aragonite but also to calcium phosphate ceramics, particularly in bone sites with the large bone remodelling. Highlights: Black-Right-Pointing-Pointer Macroporous calcite manufacturing with controlled architecture as bone substitute Black-Right-Pointing-Pointer Cytotoxicity: adaptation of the colony-forming method with the target cells: MC3T3-E1 osteoblasts Black-Right-Pointing-Pointer Study of osteoblast proliferation and activity on calcite, HA and TCP.

  18. Minimally Invasive Alveolar Ridge Preservation Utilizing an In Situ Hardening β-Tricalcium Phosphate Bone Substitute: A Multicenter Case Series

    Directory of Open Access Journals (Sweden)

    Minas D. Leventis

    2016-01-01

    Full Text Available Ridge preservation measures, which include the filling of extraction sockets with bone substitutes, have been shown to reduce ridge resorption, while methods that do not require primary soft tissue closure minimize patient morbidity and decrease surgical time and cost. In a case series of 10 patients requiring single extraction, in situ hardening beta-tricalcium phosphate (β-TCP granules coated with poly(lactic-co-glycolic acid (PLGA were utilized as a grafting material that does not necessitate primary wound closure. After 4 months, clinical observations revealed excellent soft tissue healing without loss of attached gingiva in all cases. At reentry for implant placement, bone core biopsies were obtained and primary implant stability was measured by final seating torque and resonance frequency analysis. Histological and histomorphometrical analysis revealed pronounced bone regeneration (24.4 ± 7.9% new bone in parallel to the resorption of the grafting material (12.9 ± 7.7% graft material while high levels of primary implant stability were recorded. Within the limits of this case series, the results suggest that β-TCP coated with polylactide can support new bone formation at postextraction sockets, while the properties of the material improve the handling and produce a stable and porous bone substitute scaffold in situ, facilitating the application of noninvasive surgical techniques.

  19. Minimally Invasive Alveolar Ridge Preservation Utilizing an In Situ Hardening β-Tricalcium Phosphate Bone Substitute: A Multicenter Case Series

    Science.gov (United States)

    Leventis, Minas D.; Fairbairn, Peter; Kakar, Ashish; Leventis, Angelos D.; Margaritis, Vasileios; Lückerath, Walter; Horowitz, Robert A.; Rao, Bappanadu H.; Lindner, Annette; Nagursky, Heiner

    2016-01-01

    Ridge preservation measures, which include the filling of extraction sockets with bone substitutes, have been shown to reduce ridge resorption, while methods that do not require primary soft tissue closure minimize patient morbidity and decrease surgical time and cost. In a case series of 10 patients requiring single extraction, in situ hardening beta-tricalcium phosphate (β-TCP) granules coated with poly(lactic-co-glycolic acid) (PLGA) were utilized as a grafting material that does not necessitate primary wound closure. After 4 months, clinical observations revealed excellent soft tissue healing without loss of attached gingiva in all cases. At reentry for implant placement, bone core biopsies were obtained and primary implant stability was measured by final seating torque and resonance frequency analysis. Histological and histomorphometrical analysis revealed pronounced bone regeneration (24.4 ± 7.9% new bone) in parallel to the resorption of the grafting material (12.9 ± 7.7% graft material) while high levels of primary implant stability were recorded. Within the limits of this case series, the results suggest that β-TCP coated with polylactide can support new bone formation at postextraction sockets, while the properties of the material improve the handling and produce a stable and porous bone substitute scaffold in situ, facilitating the application of noninvasive surgical techniques. PMID:27190516

  20. A Bone Sample Containing a Bone Graft Substitute Analyzed by Correlating Density Information Obtained by X-ray Micro Tomography with Compositional Information Obtained by Raman Microscopy

    Directory of Open Access Journals (Sweden)

    Johann Charwat-Pessler

    2015-06-01

    Full Text Available The ability of bone graft substitutes to promote new bone formation has been increasingly used in the medical field to repair skeletal defects or to replace missing bone in a broad range of applications in dentistry and orthopedics. A common way to assess such materials is via micro computed tomography (µ-CT, through the density information content provided by the absorption of X-rays. Information on the chemical composition of a material can be obtained via Raman spectroscopy. By investigating a bone sample from miniature pigs containing the bone graft substitute Bio Oss®, we pursued the target of assessing to what extent the density information gained by µ-CT imaging matches the chemical information content provided by Raman spectroscopic imaging. Raman images and Raman correlation maps of the investigated sample were used in order to generate a Raman based segmented image by means of an agglomerative, hierarchical cluster analysis. The resulting segments, showing chemically related areas, were subsequently compared with the µ-CT image by means of a one-way ANOVA. We found out that to a certain extent typical gray-level values (and the related histograms in the µ-CT image can be reliably related to specific segments within the image resulting from the cluster analysis.

  1. Direct 3D powder printing of biphasic calcium phosphate scaffolds for substitution of complex bone defects.

    Science.gov (United States)

    Castilho, Miguel; Moseke, Claus; Ewald, Andrea; Gbureck, Uwe; Groll, Jürgen; Pires, Inês; Teßmar, Jörg; Vorndran, Elke

    2014-03-01

    The 3D printing technique based on cement powders is an excellent method for the fabrication of individual and complex bone substitutes even in the case of large defects. The outstanding bone remodeling capacity of biphasic calcium phosphates (BCPs) containing hydroxyapatite (HA) as well as tricalcium phosphate (TCP) in varying ratios makes the adaption of powder systems resulting in BCP materials to this fabrication technique a desirable aim. This study presents the synthesis and characterization of a novel powder system for the 3D printing process, intended for the production of complexly shaped BCP scaffolds by a hydraulic setting reaction of calcium carbonate and TCP with phosphoric acid. The HA/TCP ratio in the specimens could be tailored by the calcium/phosphate ratio of the starting powder. The scaffolds could be fabricated with a dimensional accuracy of >96.5% and a minimal macro pore size of 300 µm. Independent of the phase composition the printed specimens showed a microporosity of approximately 68%, while the compressive strength strongly depended on the chemical composition and increased with rising TCP content in the scaffolds to a maximum of 1.81 MPa. Post-treatment of the scaffolds with a polylactic-co-glycolic acid-solution enhanced the mechanical properties by a factor of 8. In vitro studies showed that all BCP scaffolds were cytocompatible and enhanced the cell viability as well as the cell proliferation, as compared with pure TCP. Cell proliferation is even better on BCP when compared to HA and cell viability is in a similar range on these materials.

  2. Bone Regeneration Using a Mixture of Silicon-Substituted Coral HA and β-TCP in a Rat Calvarial Bone Defect Model

    Directory of Open Access Journals (Sweden)

    Jiyeon Roh

    2016-02-01

    Full Text Available The demand of bone graft materials has been increasing. Among various origins of bone graft materials, natural coral composed of up to 99% calcium carbonate was chosen and converted into hydroxyapatite (HA; silicon was then substituted into the HA. Then, the Si-HA was mixed with β-tricalcium phosphate (TCP in the ratios 100:0 (S100T0, 70:30 (S70T30, 60:40 (S60T40, and 50:50 (S50T50. The materials were implanted for four and eight weeks in a rat calvarial bone defect model (8 mm. The MBCPTM (HA:β-TCP = 60:40, Biomatalante, Vigneux de Bretagne, France was used as a control. After euthanasia, the bone tissue was analyzed by making histological slides. From the results, S60T40 showed the fastest bone regeneration in four weeks (p < 0.05. In addition, S60T40, S50T50, and MBCPTM showed significant new bone formation in eight weeks (p < 0.05. In conclusion, Si-HA/TCP showed potential as a bone graft material.

  3. Piezoelectric valve

    Science.gov (United States)

    Petrenko, Serhiy Fedorovich

    2013-01-15

    A motorized valve has a housing having an inlet and an outlet to be connected to a pipeline, a saddle connected with the housing, a turn plug having a rod, the turn plug cooperating with the saddle, and a drive for turning the valve body and formed as a piezoelectric drive, the piezoelectric drive including a piezoelectric generator of radially directed standing acoustic waves, which is connected with the housing and is connectable with a pulse current source, and a rotor operatively connected with the piezoelectric generator and kinematically connected with the rod of the turn plug so as to turn the turn plug when the rotor is actuated by the piezoelectric generator.

  4. Ability of bone graft substitutes to support the osteoprogenitor cells: An in-vitro study

    Institute of Scientific and Technical Information of China (English)

    Ziad; Dahabreh; Michalis; Panteli; Ippokratis; Pountos; Mark; Howard; Peter; Campbell; Peter; V; Giannoudis

    2014-01-01

    AIM: To compare seven commercially available bone graft substitutes(BGS) in terms of these properties and without using any additional biological growth factors.METHODS: Porcine osteoprogenitor cells were loaded on seven commercially available BGS and allowed to proliferate for one week followed by osteogenic induction. Staining for live/dead cells as well as scanning electron microscopy(SEM) was carried out to determine viability and cellular binding. Further outcome measures included alkaline phosphatase(ALP) assays with normalisation for DNA content to quantify osteogenic potential. Negative and positive control experiments were carried out in parallel to validate the results.RESULTS: Live/dead and SEM imaging showed higher viability and attachment with β-tricalcium phosphate(β-TCP) than with other BGS(P < 0.05). The average ALP activity in nmol/mL(normalised value for DNA content in nmol/μg DNA) per sample was 657.58(132.03) for β-TCP, 36.22(unable to normalise) for calcium sulphate, 19.93(11.39) for the Hydroxyapatite/Tricalcium Phosphate composite, 14.79(18.53) for polygraft, 13.98(8.15) for the highly porous β-Tricalcium Phosphate, 5.56(10.0) for polymers, and 3.82(3.8) for Hydroxyapatite.CONCLUSION: Under the above experimental conditions, β-TCP was able to maintain better the viability of osteoprogenitor cells and allow proliferation and differentiation(P < 0.05).

  5. In Vivo Models for the Evaluation of the Osteogenic Potency of Bone Substitutes Seeded with Mesenchymal Stem Cells of Human Origin: A Concise Review.

    Science.gov (United States)

    Westhauser, Fabian; Senger, Anne-Sophie; Reible, Bruno; Moghaddam, Arash

    2017-09-01

    Research concerning bone substitutes is one of the most challenging fields in orthopedic research and has a high clinical relevance, especially since the currently available bone substitutes are limited in their osteostimulative capabilities. In vitro models for the evaluation of the properties of bone substitutes allow the use of human mesenchymal stem cells (hMSCs) seeded onto scaffolds, but suffer from the lack of a physiological environment for those cells. Most in vivo models include the use of non-hMSC and are therefore lacking in clinical relevance. To overcome these issues, in vivo models were created that allow the evaluation of hMSC-seeded bone substitutes, combining the advantages of the use of human cells with the physiological conditions of an organism in vivo. In brief, models usually aim for bone formation in immunocompromised rodents. The subcutaneous implantation of scaffolds is most widely performed, showing low complication rates along with good results, but suffering from inferior vascularization of the implants and the absence of the realistic structural and mechanical conditions of bone. Orthotopic implantation, for example in calvarian or long bone defects, provides the most appropriate surrounding for hMSC-seeded scaffolds. However, parallel host-induced bone formation is a major limitation. This review summarizes in vivo models for the evaluation of the osteogenic potency of bone substitutes seeded with mesenchymal stem cells of human origin.

  6. 湿度对骨内压电信号的影响%On the Influence of Relative Humidity on Piezoelectric Signals in Bone

    Institute of Scientific and Technical Information of China (English)

    富东慧; 侯振德; 秦庆华; 卢晨霞

    2009-01-01

    对不同相对湿度下的骨压电电压和压电电荷信号进行测量研究,来考察湿度对骨压电信号的影响.采用三点弯曲干骨试样,以梯形脉冲载荷的方式进行加载,分别应用超高输入阻抗的生物信号放大器和电荷放大器测量了三种不同相对湿度下的骨压电电压和压电电荷信号波形.结果表明,骨压电电压峰值随湿度的增加而下降很快,当湿度从30%增至60%时,电压降幅达到了80%左右;基于测试原理的不同,骨压电电荷也随湿度的增加而下降,其降幅较小.由此可以推断,骨在体内湿润的状态下,受力变形时压电电压幅值可能趋于零.电荷的产生和瞬时泄放有可能是骨在体内的动态载荷作用下的压电效应的表现形式.%The piezoelectric effect of bone is related to relative humidity levels. Under trapezoidal pulse loading, piezoelectric signals of dry bone samples three-point bending were measured at different relative humidity levels. Piezo-voltages were obtained by using an ultra high input impedance bioamplifier. For the sake of comparing, piezo-charges of bone were also measured. Results show that piezo-voltage of bone quickly decreases with humidity increasing. Piezo-voltage decreases around 80% along with the relative humidity increases from 30% to 60%. The measured piezo-charge also decreases at lower rate along with humidity increasing due to different test principle. It is concluded that piezo-voltage induced by deformation of bone may be performed in a pulse style under dynamic loads.

  7. IN VIVO PERFORMANCE OF THE EXPERIMENTAL CHITOSAN BASED BONE SUBSTITUTE--ADVANCED THERAPY MEDICINAL PRODUCT. A STUDY IN SHEEP.

    Science.gov (United States)

    Bojar, Witold; Kucharska, Martyna; Ciach, Tomasz; Paśnik, Iwona; Korobowicz, Elzbieta; Patkowski, Krzysztof; Gruszecki, Tomasz; Szymanowski, Marek; Rzodkiewicz, Przemysław

    2016-01-01

    When evaluating a novel bone substitute material, advanced in vivo testing is an important step in development and safety affirmation. Sheep seems to be a valuable model for human bone turnover and remodeling activity. The experimental material composed with the stem cells is an advanced therapy medicinal product (acc. to EC Regulation 1394/2007). Our research focuses on histological differences in bone formation (guided bone regeneration--GBR) in sheep maxillas after implantation of the new chitosan/tricalcium phosphate/alginate (CH/TCP/Alg) biomaterial in comparison to the commercially available xenogenic bone graft and a/m enhanced with the stem cells isolated from the adipose tissue. Twelve adult female sheep of BCP synthetic line, weighing 60-70 kg were used for the study. The 11 mm diameter defects in maxilla bone were prepared with a trephine bur under general anesthesia and then filled with the bone substitute materials: CH/TCP/Alg, BioOss Collagen, Geistlich AG (BO), CH/TCP/Alg composed with the stem cells (CH/S) or left just with the blood clot (BC). Inbreeding cycle of the animals terminated at 4 months after surgery. Dissected specimens of the maxilla were evaluated histologically and preliminary under microtomography. Histological evaluation showed early new bone formation observed around the experimental biomaterial and commercially available BO. There were no features of purulent inflammation and necrosis, or granulomatous inflammation. Microscopic examination after 4 months following the surgery revealed trabecular bone formation around chitosan based bone graft and xenogenic material with no significant inflammatory response. Different results--no bone recreation were observed for the negative control (BC). In conclusion, the tested materials (CH/TCP/Alg and BO) showed a high degree of biocompatibility and some osteoconductivity in comparison with the control group. Although the handiness, granules size and setting time of CHffCP/Alg may be refined

  8. Maxillary sinus lift with solely autogenous bone compared to a combination of autogenous bone and growth factors or (solely) bone substitutes. A systematic review : a systematic review

    NARCIS (Netherlands)

    Rickert, D.; Slater, J. J. R. Huddleston; Meijer, H. J. A.; Vissink, A.; Raghoebar, G. M.

    Literature regarding the outcome of maxillary sinus floor elevation to create sufficient bone fraction to enable implant placement was systematically reviewed. Bone fraction and implant survival rate were assessed to determine whether grafting material or applied growth factor affected bone

  9. Clinical effectiveness of combining platelet rich fibrin with alloplastic bone substitute for the management of combined endodontic periodontal lesion

    Directory of Open Access Journals (Sweden)

    Lata Goyal

    2014-02-01

    Full Text Available The term "endo-perio" lesion has been proposed to describe the destructive lesion resulting from inflammatory products found in varying degrees in both the periodontium and the pulpal tissues. In most of the cases, clinical symptoms disappear following successful endodontic therapy. However failure after conventional root canal treatment calls for surgical intervention. A 35 year old male patient with endo-perio lesion in right maxillary lateral incisor was treated with platelet rich fibrin (PRF and alloplastic bone substitute after conventional endodontic therapy. At the end of 6 months there was gain in clinical attachment, increased radiographic bone fill and reduction in probing depth which was maintained till 18 month follow-up. Present case report aims to evaluate the efficacy of PRF and alloplastic bone substitute in the management of intrabony defect associated with endo-perio lesion in maxillary lateral incisor because the healing potential of PRF and bone graft has not been widely studied in endodontics. The use of PRF allows the clinician to optimize tissue remodelling, wound healing and angiogenesis by the local delivery of growth factors and proteins. The novel technique described here enables the clinician to be benefited from the full regenerative capacity of this autologous biologic material.

  10. Mechanism of bone incorporation of beta-TCP bone substitute in open wedge tibial osteotomy in patients.

    NARCIS (Netherlands)

    Gaasbeek, R.D.A.; Toonen, H.G.; Heerwaarden, R.J. van; Buma, P.

    2005-01-01

    A histological study was performed of bone biopsies from 16 patients (17 biopsies) treated with open wedge high tibial osteotomies for medial knee osteoarthritis. The open wedge osteotomies were filled with a wedge of osteoconductive beta tricalcium phosphate (beta-TCP) ceramic bone replacement. At

  11. Efficacy of a small cell-binding peptide coated hydroxyapatite substitute on bone formation and implant fixation in sheep.

    Science.gov (United States)

    Ding, Ming; Andreasen, Christina M; Dencker, Mads L; Jensen, Anders E; Theilgaard, Naseem; Overgaard, Søren

    2015-04-01

    Cylindrical critical size defects were created at the distal femoral condyles bilaterally of eight female adult sheep. Titanium implants with 2-mm concentric gaps were inserted and the gaps were filled with one of the four materials: allograft; a synthetic 15-amino acid cell-binding peptide coated hydroxyapatite (ABM/P-15); hydroxyapatite + βtricalciumphosphate+ Poly-Lactic-Acid (HA/βTCP-PDLLA); or ABM/P-15+HA/βTCP-PDLLA. After nine weeks, bone-implant blocks were harvested and sectioned for micro-CT scanning, push-out test, and histomorphometry. Significant bone formation and implant fixation could be observed in all four groups. Interestingly, the microarchitecture of the ABM/P-15 group was significantly different from the control group. Tissue volume fraction and thickness were significantly greater in the ABM/P-15 group than in the allograft group. Bone formation and bone ingrowth to porous titanium implant were not significantly different among the four groups. The ABM/P-15 group had similar shear mechanical properties on implant fixation as the allograft group. Adding HA/βTCP-PDLLA to ABM/P-15 did not significantly change these parameters. This study revealed that ABM/P-15 had significantly bone formation in concentric gap, and its enhancements on bone formation and implant fixation were at least as good as allograft. It is suggested that ABM/P-15 might be a good alternative biomaterial for bone implant fixation in this well-validated critical-size defect gap model in sheep. Nevertheless, future clinical researches should focus on prospective, randomized, controlled trials in order to fully elucidate whether ABM/P-15 could be a feasible candidate for bone substitute material in orthopedic practices.

  12. Bone Indices in Thyroidectomized Patients on Long-Term Substitution Therapy with Levothyroxine Assessed by DXA and HR-pQCT

    Directory of Open Access Journals (Sweden)

    Emil Moser

    2015-01-01

    Full Text Available Background. Studies on bone effects of long-term substitution therapy with levothyroxine (LT4 have shown discrepant results. Previous studies have, however, not evaluated volumetric bone mineral densities (vBMD, bone structure, and strength using high resolution peripheral quantitative computed tomography (HR-pQCT and finite element analysis (FEA. Using a cross-sectional design, we aimed to determine whether BMD, structure, and strength are affected in hypothyroid patients on LT4 substitution therapy. Methods. We compared 49 patients with well-substituted hypothyroidism with 49 age- and gender-matched population based controls. Areal BMD was assessed by DXA, vBMD and bone geometry by HR-pQCT, and bone strength by FEA. Results. Patients had been thyroidectomized due to thyroid cancer (10% and nontoxic (33% or toxic goiter (57%. 82% were women. TSH levels did not differ between groups, but patients had significantly higher levels of T4 (p<0.001 and lower levels of T3 (p<0.01. Compared to controls, patients had higher levels of magnesium (p<0.05, whereas ionized calcium and PTH were lower (p<0.05. Bone scans did not reveal any differences in BMD, bone geometry, or strength. Conclusion. If patients with hypothyroidism are well-substituted with LT4, the disease does not affect bone indices to any major degree.

  13. Novel bone substitute composed of chitosan and strontium-doped α-calcium sulfate hemihydrate: Fabrication, characterisation and evaluation of biocompatibility

    Energy Technology Data Exchange (ETDEWEB)

    Chen, Yirong; Zhou, Yilin [Department of Orthopaedics and Traumatology, Nanfang Hospital, Southern Medical University, Guangzhou 510515 (China); Yang, Shenyu [Department of Materials Science and Engineering, College of Science and Engineering, Jinan University, Guangzhou 510632 (China); Li, Jiao Jiao [Biomaterials and Tissue Engineering Research Unit, School of AMME, University of Sydney, Sydney, NSW 2006 (Australia); Li, Xue; Ma, Yunfei; Hou, Yilong; Jiang, Nan; Xu, Changpeng; Zhang, Sheng [Department of Orthopaedics and Traumatology, Nanfang Hospital, Southern Medical University, Guangzhou 510515 (China); Zeng, Rong [Department of Materials Science and Engineering, College of Science and Engineering, Jinan University, Guangzhou 510632 (China); Tu, Mei, E-mail: tumei@jnu.edu.cn [Department of Materials Science and Engineering, College of Science and Engineering, Jinan University, Guangzhou 510632 (China); Yu, Bin, E-mail: yubinol@163.com [Department of Orthopaedics and Traumatology, Nanfang Hospital, Southern Medical University, Guangzhou 510515 (China)

    2016-09-01

    Calcium sulfate is in routine clinical use as a bone substitute, offering the benefits of biodegradability, biocompatibility and a long history of use in bone repair. The osteoconductive properties of calcium sulfate may be further improved by doping with strontium ions. Nevertheless, the high degradation rate of calcium sulfate may impede bone healing as substantial material degradation may occur before the healing process is complete. The purpose of this study is to develop a novel composite bone substitute composed of chitosan and strontium-doped α-calcium sulfate hemihydrate in the form of microcapsules, which can promote osteogenesis while matching the natural rate of bone healing. The developed microcapsules exhibited controlled degradation that facilitated the sustained release of strontium ions. In vitro testing showed that the microcapsules had minimal cytotoxicity and ability to inhibit bacterial growth. In vivo testing in a mouse model showed the absence of genetic toxicity and low inflammatory potential of the microcapsules. The novel microcapsules developed in this study demonstrated suitable degradation characteristics for bone repair as well as favourable in vitro and in vivo behaviour, and hold promise for use as an alternative bone substitute in orthopaedic surgery. - Highlights: • Chitosan + Sr-doped α-calcium sulfate hemihydrate microcapsules were synthesised. • The novel composite microcapsules had potential application as a bone substitute. • The microcapsules showed controlled degradation and release of strontium ions. • The microcapsules showed in vitro biocompatibility by cytotoxicity test. • The microcapsules showed in vivo biocompatibility in a mouse model.

  14. The efficacy of poly-d,l-lactic acid- and hyaluronic acid-coated bone substitutes on implant fixation in sheep

    Directory of Open Access Journals (Sweden)

    Christina M. Andreasen

    2017-01-01

    Conclusion: This study demonstrates that HA/βTCP granules coated with PDLLA and HyA have similar bone ingrowth and implant fixation as those with allograft, and with mechanical properties resembling those of allograft in advance, they may be considered as alternative substitute materials for bone formation in sheep.

  15. Evaluation of Osteoconductive and Osteogenic Potential of a Dentin-Based Bone Substitute Using a Calvarial Defect Model

    Directory of Open Access Journals (Sweden)

    Ibrahim Hussain

    2012-01-01

    Full Text Available The aim of this study was to assess the osteoconductive and osteogenic properties of processed bovine dentin using a robust rabbit calvarial defect model. In total, 16 New Zealand White rabbits were operated to create three circular defects in the calvaria. One defect was left unfilled, one filled with collected autogenous bone, and the third defect was filled with the dentin-based bone substitute. Following surgery and after a healing period of either 1 or 6 weeks, a CT scan was obtained. Following sacrificing, the tissues were processed for histological examination. The CT data showed the density in the area grafted with the dentin-based material was higher than the surrounding bone and the areas grafted with autologous bone after 1 week and 6 weeks of healing. The area left unfilled remained an empty defect after 1 week and 6 weeks. Histological examination of the defects filled with the dentin product after 6 weeks showed soft tissue encapsulation around the dentin particles. It can be concluded that the rabbit calvarial model used in this study is a robust model for the assessment of bone materials. Bovine dentin is a biostable material; however, it may not be suitable for repairing large 4-wall defects.

  16. Antibacterial and biocompatible properties of vancomycin-loaded nano-hydroxyapatite/collagen/poly (lactic acid) bone substitute

    Institute of Scientific and Technical Information of China (English)

    Xiaojie Lian; Huanye Liu; Xiumei Wang; Suju Xu; Fuzhai Cui; Xizhuang Bai

    2013-01-01

    Infected bone defects are normally regarded as contraindications for bone grafting. In the present study, an antibacterial bone graft substitute was synthesized by loading vancomycin (VCM) in our previously developed mineralized collagen based composite, nano-hydroxyapatite/collagen/poly (lactic acid) (nHAC/PLA), aiming to repair large size bone defects and inhibit related infections simultaneously. The VCM/nHAC/PLA showed typical porous structure with a porosity of (80.776.7)%and compressive strength of 1.52 MPa. The delivery of VCM from VCM/nHAC/PLA was detected in vitro for up to 4 weeks. And their antibacterial properties were determined using inhibition ratio assay and inhibition zone assay. Pretty high level of inhibition ratio (more than 99%) was obtained in VCM/nHAC/PLA group. Additionally, a distinct inhibition zone was clearly formed in Staphylococcus aureus bacterium incubation dish with VCM/nHAC/PLA disc for up to 18 days of incubation. Moreover, both of the nHAC/PLA composites with or without VCM exhibited favorable in vitro and in vivo biocompatibilities for rabbit marrow stromal cells (MSCs) adhesion, spreading, proliferation, and triggering no obvious inflammation responses in subcutaneous implantation. Our results suggested that the VCM/nHAC/PLA performed ideal antibacterial property and biocompatibility and has great promise for the treatment of bone defect-related infections in orthopedic surgeries.

  17. A novel injectable, cohesive and toughened Si-HPMC (silanized-hydroxypropyl methylcellulose) composite calcium phosphate cement for bone substitution.

    Science.gov (United States)

    Liu, Weizhen; Zhang, Jingtao; Rethore, Gildas; Khairoun, Khalid; Pilet, Paul; Tancret, Franck; Bouler, Jean-Michel; Weiss, Pierre

    2014-07-01

    This study reports on the incorporation of the self-setting polysaccharide derivative hydrogel (silanized-hydroxypropyl methylcellulose, Si-HPMC) into the formulation of calcium phosphate cements (CPCs) to develop a novel injectable material for bone substitution. The effects of Si-HPMC on the handling properties (injectability, cohesion and setting time) and mechanical properties (Young's modulus, fracture toughness, flexural and compressive strength) of CPCs were systematically studied. It was found that Si-HPMC could endow composite CPC pastes with an appealing rheological behavior at the early stage of setting, promoting its application in open bone cavities. Moreover, Si-HPMC gave the composite CPC good injectability and cohesion, and reduced the setting time. Si-HPMC increased the porosity of CPCs after hardening, especially the macroporosity as a result of entrapped air bubbles; however, it improved, rather than compromised, the mechanical properties of composite CPCs, which demonstrates a strong toughening and strengthening effect. In view of the above, the Si-HPMC composite CPC may be particularly promising as bone substitute material for clinic application.

  18. EVALUATION OF POSTERIOR SPINAL FUSION WITH PEDICLE SCREWS AND RODS WITH BONE SUBSTITUTES IN GRADE I AND II SPONDYLOLISTHESIS

    Directory of Open Access Journals (Sweden)

    Chaitanya Reddy

    2016-04-01

    Full Text Available BACKGROUND Low-back pain is the commonest condition encountered day in and day out of an orthopaedic practice. Incidence of spondylolisthesis in normal population is around 5-7%. No matter what the aetiology is, patient has significant functional disability. OBJECTIVES To study the efficacy of pedicular screw rod system and posterolateral fusion with bone substitutes in spondylolisthesis, and to study the complications associated with this treatment modality. METHODOLOGY From July 2012 to September 2014, a total of 30 patients operated with posterolateral fusion were followed up and evaluated based on VAS for low back pain and Japanese orthopaedic association scoring system. RESULTS The mean difference between pre-operative and post-operative VAS score is 3SD with a p value of <0.001, which is strongly significant. The pre-operative and post-operative JOA score has an improvement of 73.4% with a p value of <0.001, which is strongly significant. Rate of improvement was excellent in 16.7%, good in 53.3%, fair in 23.3% and poor in 6.3% of patients; 82% of patients had bone fusion by the end of 8 months. CONCLUSION Pedicular screw rod system with postero-lumbar fusion with bone substitute is safe, promising and appealing technique for low-grade spondylolisthesis with early post-operative pain relief.

  19. Maxillary sinus lift with solely autogenous bone compared to a combination of autogenous bone and growth factors or (solely) bone substitutes. A systematic review : a systematic review

    NARCIS (Netherlands)

    Rickert, D.; Slater, J. J. R. Huddleston; Meijer, H. J. A.; Vissink, A.; Raghoebar, G. M.

    2012-01-01

    Literature regarding the outcome of maxillary sinus floor elevation to create sufficient bone fraction to enable implant placement was systematically reviewed. Bone fraction and implant survival rate were assessed to determine whether grafting material or applied growth factor affected bone fraction

  20. Posterolateral arthrodesis in lumbar spine surgery using autologous platelet-rich plasma and cancellous bone substitute: an osteoinductive and osteoconductive effect.

    Science.gov (United States)

    Tarantino, Roberto; Donnarumma, Pasquale; Mancarella, Cristina; Rullo, Marika; Ferrazza, Giancarlo; Barrella, Gianna; Martini, Sergio; Delfini, Roberto

    2014-08-01

    Study Design Prospective cohort study. Objectives To analyze the effectiveness and practicality of using cancellous bone substitute with platelet-rich plasma (PRP) in posterolateral arthrodesis. Methods Twenty consecutive patients underwent posterolateral arthrodesis with implantation of cancellous bone substitute soaked with PRP obtained directly in the operating theater on the right hemifield and cancellous bone substitute soaked with saline solution on the right. Results Computed tomography scans at 6 and 12 months after surgery were performed in all patients. Bone density was investigated by comparative analysis of region of interest. The data were analyzed with repeated-measures variance analyses with value of density after 6 months and value of density after 12 months, using age, levels of arthrodesis, and platelet count as covariates. The data demonstrated increased bone density using PRP and heterologous cancellous block resulting in an enhanced fusion rate during the first 6 months after surgery. Conclusions PRP used with cancellous bone substitute increases the rate of fusion and bone density joining osteoinductive and osteoconductive effect.

  1. Efficacy of bone substitute material in preserving volume when placing a maxillary immediate complete denture: study protocol for the PANORAMIX randomized controlled trial.

    Science.gov (United States)

    Rignon-Bret, Christophe; Hadida, Alain; Aidan, Alexis; Nguyen, Thien-Huong; Pasquet, Gerard; Fron-Chabouis, Helene; Wulfman, Claudine

    2016-05-20

    Bone preservation is an essential issue in the context of last teeth extraction and complete edentulism. The intended treatment, whether a complete denture or an implant placement, is facilitated with a voluminous residual ridge. Bone resorption after multiple extractions has not been as well studied as the bone resorption that occurs after the extraction of a single tooth. Recent advances in bone substitute materials have revived this issue. The purpose of this study is to evaluate the interest in using bone substitute material to fill the socket after last teeth extraction in a maxillary immediate complete denture procedure compared with the conventional protocol without socket filling. A randomized, controlled, clinical trial was designed. The 34 participants eligible for maxillary immediate complete denture were divided into two groups. Complete dentures were prepared despite persistence of the last anterior teeth. The control group received a conventional treatment including denture placement immediately after extractions. In the experimental group, in addition to the immediate denture placement, a xenograft bone-substitute material (Bio-Oss Collagen®) was placed in the fresh sockets. The primary outcome of the study is to compare mean bone ridge height loss 1 year after maxillary immediate complete denture placement, with or without bone-substitute material, in incisor and canine sockets. The secondary outcomes are to compare the average bone ridge height and width loss for each extraction site. An original quantitative evaluation method using cone beam computed tomography was designed for reproducible measurements, with a radio-opaque denture duplicate. Two independent operators perform the radiologic measurements. The immediate complete denture technique limits bone resorption in multiple extraction situations and thus allows better denture retention and better options for implant placement. To compare the benefit of using any bone socket-filling material

  2. Coralline hydroxyapatite is a suitable bone graft substitute in an intra-articular goat defect model.

    Science.gov (United States)

    Koëter, S; Tigchelaar, S J; Farla, P; Driessen, L; van Kampen, A; Buma, P

    2009-07-01

    Intra-articular defects can be filled with an autologous bone graft taken from the iliac crest. This can be indicated after trauma or following correcting osteotomy. Patients may encounter donor site morbidity after this procedure. In this in vivo study, we studied if coralline hydroxyapatite (CHA) is a suitable material to replace autologous bone graft to fill a defect in the femoral trochlea of goats. CHA did not evoke any negative reaction in the synovium, and the articular cartilage was comparable to controls. In the bone graft group, we found scattered areas of (enchondral formed) bone. Most bone graft had been resorbed or remodeled, and the scarce remnants were incorporated into new bone. Resorption of CHA was limited or absent and most CHA was surrounded by new bone. In areas with fragmented CHA, close to the joint surface, numerous giant cells were found. The study shows that in this animal model, CHA inserted in a defect that directly communicates with the joint space incorporates into bone. This study did not show any negative effects of CHA in a joint environment.

  3. Synchrotron μCT Imaging of Bone, Titanium implants and Bone Substitutes -a Systematic Review of the Literature

    DEFF Research Database (Denmark)

    Neldam, Camilla Albeck; Pinholt, Else Marie

    2014-01-01

    examinations, SRμCT is considered as a gold standard to image trabecular bone microarchitecture since it is possible in a 3D manner to visualize fine structural elements within mineralized tissue such as osteon boundaries, rods and plates structures, cement lines, and differences in mineralization...

  4. Autologous serum improves bone formation in a primary stable silica-embedded nanohydroxyapatite bone substitute in combination with mesenchymal stem cells and rhBMP-2 in the sheep model

    Directory of Open Access Journals (Sweden)

    Boos AM

    2014-11-01

    Full Text Available Anja M Boos,1,* Annika Weigand,1,* Gloria Deschler,1 Thomas Gerber,2 Andreas Arkudas,1 Ulrich Kneser,1 Raymund E Horch,1 Justus P Beier11Department of Plastic and Hand Surgery, University Hospital of Erlangen, Friedrich-Alexander-University of Erlangen-Nürnberg FAU, Erlangen, 2Institute of Physics, University of Rostock, Rostock, Germany *These authors contributed equally to this work Abstract: New therapeutic strategies are required for critical size bone defects, because the gold standard of transplanting autologous bone from an unharmed area of the body often leads to several severe side effects and disadvantages for the patient. For years, tissue engineering approaches have been seeking a stable, axially vascularized transplantable bone replacement suitable for transplantation into the recipient bed with pre-existing insufficient conditions. For this reason, the arteriovenous loop model was developed and various bone substitutes have been vascularized. However, it has not been possible thus far to engineer a primary stable and axially vascularized transplantable bone substitute. For that purpose, a primary stable silica-embedded nanohydroxyapatite (HA bone substitute in combination with blood, bone marrow, expanded, or directly retransplanted mesenchymal stem cells, recombinant human bone morphogenetic protein 2 (rhBMP-2, and different carrier materials (fibrin, cell culture medium, autologous serum was tested subcutaneously for 4 or 12 weeks in the sheep model. Autologous serum lead to an early matrix change during degradation of the bone substitute and formation of new bone tissue. The best results were achieved in the group combining mesenchymal stem cells expanded with 60 µg/mL rhBMP-2 in autologous serum. Better ingrowth of fibrovascular tissue could be detected in the autologous serum group compared with the control (fibrin. Osteoclastic activity indicating an active bone remodeling process was observed after 4 weeks, particularly

  5. Piezoelectric Film.

    Science.gov (United States)

    Garrison, Steve

    1992-01-01

    Presents activities that utilize piezoelectric film to familiarize students with fundamental principles of electricity. Describes classroom projects involving chemical sensors, microbalances, microphones, switches, infrared sensors, and power generation. (MDH)

  6. Biologically inspired rosette nanotubes and nanocrystalline hydroxyapatite hydrogel nanocomposites as improved bone substitutes.

    Science.gov (United States)

    Zhang, Lijie; Rodriguez, Jose; Raez, Jose; Myles, Andrew J; Fenniri, Hicham; Webster, Thomas J

    2009-04-29

    Today, bone diseases such as bone fractures, osteoporosis and bone cancer represent a common and significant public health problem. The design of biomimetic bone tissue engineering materials that could restore and improve damaged bone tissues provides exciting opportunities to solve the numerous problems associated with traditional orthopedic implants. Therefore, the objective of this in vitro study was to create a biomimetic orthopedic hydrogel nanocomposite based on the self-assembly properties of helical rosette nanotubes (HRNs), the osteoconductive properties of nanocrystalline hydroxyapatite (HA), and the biocompatible properties of hydrogels (specifically, poly(2-hydroxyethyl methacrylate), pHEMA). HRNs are self-assembled nanomaterials that are formed from synthetic DNA base analogs in water to mimic the helical nanostructure of collagen in bone. In this study, different geometries of nanocrystalline HA were controlled by either hydrothermal or sintering methods. 2 and 10 wt% nanocrystalline HA particles were well dispersed into HRN hydrogels using ultrasonication. The nanocrystalline HA and nanocrystalline HA/HRN hydrogels were characterized by x-ray diffraction, transmission electron microscopy, and scanning electron microscopy. Mechanical testing studies revealed that the well dispersed nanocrystalline HA in HRN hydrogels possessed improved mechanical properties compared to hydrogel controls. In addition, the results of this study provided the first evidence that the combination of either 2 or 10 wt% nanocrystalline HA and 0.01 mg ml(-1) HRNs in hydrogels greatly increased osteoblast (bone-forming cell) adhesion up to 236% compared to hydrogel controls. Moreover, this study showed that HRNs stimulated HA nucleation and mineralization along their main axis in a way that is very reminiscent of the HA/collagen assembly pattern in natural bone. In summary, the presently observed excellent properties of the biomimetic nanocrystalline HA/HRN hydrogel composites

  7. Biologically inspired rosette nanotubes and nanocrystalline hydroxyapatite hydrogel nanocomposites as improved bone substitutes

    Science.gov (United States)

    Zhang, Lijie; Rodriguez, Jose; Raez, Jose; Myles, Andrew J.; Fenniri, Hicham; Webster, Thomas J.

    2009-04-01

    Today, bone diseases such as bone fractures, osteoporosis and bone cancer represent a common and significant public health problem. The design of biomimetic bone tissue engineering materials that could restore and improve damaged bone tissues provides exciting opportunities to solve the numerous problems associated with traditional orthopedic implants. Therefore, the objective of this in vitro study was to create a biomimetic orthopedic hydrogel nanocomposite based on the self-assembly properties of helical rosette nanotubes (HRNs), the osteoconductive properties of nanocrystalline hydroxyapatite (HA), and the biocompatible properties of hydrogels (specifically, poly(2-hydroxyethyl methacrylate), pHEMA). HRNs are self-assembled nanomaterials that are formed from synthetic DNA base analogs in water to mimic the helical nanostructure of collagen in bone. In this study, different geometries of nanocrystalline HA were controlled by either hydrothermal or sintering methods. 2 and 10 wt% nanocrystalline HA particles were well dispersed into HRN hydrogels using ultrasonication. The nanocrystalline HA and nanocrystalline HA/HRN hydrogels were characterized by x-ray diffraction, transmission electron microscopy, and scanning electron microscopy. Mechanical testing studies revealed that the well dispersed nanocrystalline HA in HRN hydrogels possessed improved mechanical properties compared to hydrogel controls. In addition, the results of this study provided the first evidence that the combination of either 2 or 10 wt% nanocrystalline HA and 0.01 mg ml-1 HRNs in hydrogels greatly increased osteoblast (bone-forming cell) adhesion up to 236% compared to hydrogel controls. Moreover, this study showed that HRNs stimulated HA nucleation and mineralization along their main axis in a way that is very reminiscent of the HA/collagen assembly pattern in natural bone. In summary, the presently observed excellent properties of the biomimetic nanocrystalline HA/HRN hydrogel composites

  8. Biologically inspired rosette nanotubes and nanocrystalline hydroxyapatite hydrogel nanocomposites as improved bone substitutes

    Energy Technology Data Exchange (ETDEWEB)

    Zhang Lijie; Webster, Thomas J [Division of Engineering, Brown University, 182 Hope Street, Providence, RI 02912 (United States); Rodriguez, Jose; Raez, Jose; Myles, Andrew J; Fenniri, Hicham [National Institute for Nanotechnology and Department of Chemistry, University of Alberta, 11421 Saskatchewan Drive, Edmonton, AB, T6G 2M9 (Canada)], E-mail: hicham.fenniri@ualberta.ca, E-mail: thomas_webster@brown.edu

    2009-04-29

    Today, bone diseases such as bone fractures, osteoporosis and bone cancer represent a common and significant public health problem. The design of biomimetic bone tissue engineering materials that could restore and improve damaged bone tissues provides exciting opportunities to solve the numerous problems associated with traditional orthopedic implants. Therefore, the objective of this in vitro study was to create a biomimetic orthopedic hydrogel nanocomposite based on the self-assembly properties of helical rosette nanotubes (HRNs), the osteoconductive properties of nanocrystalline hydroxyapatite (HA), and the biocompatible properties of hydrogels (specifically, poly(2-hydroxyethyl methacrylate), pHEMA). HRNs are self-assembled nanomaterials that are formed from synthetic DNA base analogs in water to mimic the helical nanostructure of collagen in bone. In this study, different geometries of nanocrystalline HA were controlled by either hydrothermal or sintering methods. 2 and 10 wt% nanocrystalline HA particles were well dispersed into HRN hydrogels using ultrasonication. The nanocrystalline HA and nanocrystalline HA/HRN hydrogels were characterized by x-ray diffraction, transmission electron microscopy, and scanning electron microscopy. Mechanical testing studies revealed that the well dispersed nanocrystalline HA in HRN hydrogels possessed improved mechanical properties compared to hydrogel controls. In addition, the results of this study provided the first evidence that the combination of either 2 or 10 wt% nanocrystalline HA and 0.01 mg ml{sup -1} HRNs in hydrogels greatly increased osteoblast (bone-forming cell) adhesion up to 236% compared to hydrogel controls. Moreover, this study showed that HRNs stimulated HA nucleation and mineralization along their main axis in a way that is very reminiscent of the HA/collagen assembly pattern in natural bone. In summary, the presently observed excellent properties of the biomimetic nanocrystalline HA/HRN hydrogel

  9. Histological and morphometric aspects of ridge preservation with a moldable, in situ hardening bone graft substitute

    Directory of Open Access Journals (Sweden)

    Jurišić M.

    2013-01-01

    Full Text Available Biphasic calcium phosphates (BCP are widely used in alveolar ridge regeneration as a porous scaffold for new bone formation. The aim of this case series was to evaluate the regenerative effect of the combination of BCP and polylactide-co-glycolide (PLGA which can serve as a barrier membrane during bone regeneration. The study included five patients. Four months into the healing period, bone samples were collected for histological and morphometric analyses. The results of morphometric analysis showed that newly formed bone represented 32.2 ± 6.8% of the tissue, 31.9 ± 8.9% was occupied by residual graft and 35.9 ± 13.5% by soft tissue. Active osteogenesis was seen around the particles of the graft. The particles were occupied mostly by immature woven bone and connective tissue. The quality and quantity of newly formed bone, after the use of BCP/PLGA for ridge preservation, can be adequate for successful implant therapy after tooth extraction. [Projekat Ministarstva nauke Republike Srbije, br. OI 175021 i br. OI 173009

  10. In vitro degradation and cell response of calcium carbonate composite ceramic in comparison with other synthetic bone substitute materials

    Energy Technology Data Exchange (ETDEWEB)

    He, Fupo [Department of Biomedical Engineering, School of Basic Sciences, Guangzhou Medical University, Guangzhou 510182 (China); Zhang, Jing [School of Materials Science and Engineering, South China University of Technology, Guangzhou 510641 (China); Yang, Fanwen; Zhu, Jixiang; Tian, Xiumei [Department of Biomedical Engineering, School of Basic Sciences, Guangzhou Medical University, Guangzhou 510182 (China); Chen, Xiaoming, E-mail: xmchenw@126.com [Department of Biomedical Engineering, School of Basic Sciences, Guangzhou Medical University, Guangzhou 510182 (China)

    2015-05-01

    The robust calcium carbonate composite ceramics (CC/PG) can be acquired by fast sintering calcium carbonate at a low temperature (650 °C) using a biocompatible, degradable phosphate-based glass (PG) as sintering agent. In the present study, the in vitro degradation and cell response of CC/PG were assessed and compared with 4 synthetic bone substitute materials, calcium carbonate ceramic (CC), PG, hydroxyapatite (HA) and β-tricalcium phosphate (β-TCP) ceramics. The degradation rates in decreasing order were as follows: PG, CC, CC/PG, β-TCP, and HA. The proliferation of rat bone mesenchymal stem cells (rMSCs) cultured on the CC/PG was comparable with that on CC and PG, but inferior to HA and β-TCP. The alkaline phosphatase (ALP) activity of rMSCs on CC/PG was lower than PG, comparable with β-TCP, but higher than HA. The rMSCs on CC/PG and PG had enhanced gene expression in specific osteogenic markers, respectively. Compared to HA and β-TCP, the rMSCs on the CC/PG expressed relatively lower level of collagen I and runt-related transcription factor 2, but showed more considerable expression of osteopontin. Although CC, PG, HA, and β-TCP possessed impressive performances in some specific aspects, they faced extant intrinsic drawbacks in either degradation rate or mechanical strength. Based on considerable compressive strength, moderate degradation rate, good cell response, and being free of obvious shortcoming, the CC/PG is promising as another choice for bone substitute materials. - Highlights: • A calcium carbonate composite ceramic (CC/PG) was acquired. • The in vitro degradation and cell response of CC/PG were compared to 4 materials. • The CC/PG showed moderate degradation rate. • The CC/PG exhibited good cell response. • The CC/PG was free of obvious drawback compared to other materials.

  11. Axial vascularization of a large volume calcium phosphate ceramic bone substitute in the sheep AV loop model.

    Science.gov (United States)

    Beier, Justus P; Horch, Raymund E; Hess, Andreas; Arkudas, Andreas; Heinrich, Johanna; Loew, Johanna; Gulle, Heinz; Polykandriotis, Elias; Bleiziffer, Oliver; Kneser, Ulrich

    2010-03-01

    Vascularization still remains an obstacle to engineering of bone tissue with clinically relevant dimensions. Our aim was to induce axial vascularization in a large volume of a clinically approved biphasic calcium phosphate ceramic by transferring the arteriovenous (AV) loop approach to a large animal model. HA/beta-TCP granula were mixed with fibrin gel for a total volume of 16 cm(3), followed by incorporation into an isolation chamber together with an AV loop. The chambers were implanted into the groins of merino sheep and the development of vascularization was monitored by sequential non-invasive magnetic resonance imaging (MRI). The chambers were explanted after 6 and 12 weeks, the pedicle was perfused with contrast agent and specimens were subjected to micro-computed tomography (micro-CT) scan and histological analysis. Sequential MRI demonstrated a significantly increased perfusion in the HA/beta-TCP matrices over time. Micro-CT scans and histology confirmed successful axial vascularization of HA/beta-TCP constructs. This study demonstrates, for the first time, successful axial vascularization of a clinically approved bone substitute with a significant volume in a large animal model by means of a microsurgically created AV loop, thus paving the way for the first microsurgical transplantation of a tissue-engineered, axially vascularized bone with clinically relevant dimensions.

  12. Quantifying migration and polarization of murine mesenchymal stem cells on different bone substitutes by confocal laser scanning microscopy.

    Science.gov (United States)

    Roldán, J C; Chang, E; Kelantan, M; Jazayeri, L; Deisinger, U; Detsch, R; Reichert, T E; Gurtner, G C

    2010-12-01

    Cell migration is preceded by cell polarization. The aim of the present study was to evaluate the impact of the geometry of different bone substitutes on cell morphology and chemical responses in vitro. Cell polarization and migration were monitored temporally by using confocal laser scanning microscopy (CLSM) to follow green fluorescent protein (GFP)±mesenchymal stem cells (MSCs) on anorganic cancellous bovine bone (Bio-Oss(®)), β-tricalcium phosphate (β-TCP) (chronOS(®)) and highly porous calcium phosphate ceramics (Friedrich-Baur-Research-Institute for Biomaterials, Germany). Differentiation GFP±MSCs was observed using pro-angiogenic and pro-osteogenic biomarkers. At the third day of culture polarized vs. non-polarized cellular sub-populations were clearly established. Biomaterials that showed more than 40% of polarized cells at the 3rd day of culture, subsequently showed an enhanced cell migration compared to biomaterials, where non-polarized cells predominated (pculture (pculture (p=0.001). This model opens an interesting approach to understand osteoconductivity at a cellular level. MSCs are promising in bone tissue engineering considering the strong angiogenic effect before differentiation occurs. Copyright © 2010 European Association for Cranio-Maxillo-Facial Surgery. Published by Elsevier Ltd. All rights reserved.

  13. Biological evaluation of alginate-based hydrogels, with antimicrobial features by Ce(III) incorporation, as vehicles for a bone substitute

    OpenAIRE

    MORAIS, D.S.; Rodrigues, M. A.; Lopes, M A; Coelho, M.J.; Maurício, Ana Colette; Gomes, R; Amorim, Irina; Ferraz, M. P.; Santos,J.D.; Botelho, C. M.

    2013-01-01

    In this work three different hydrogels were developed to associate, as vehicles, with the synthetic bone substitute GR-HA. One based on an alginate matrix (Alg); a second on a mixture of alginate and chitosan (Alg/Ch); and a third on alginate and hyaluronate (Alg/HA), using Ca2+ ions as cross-linking agents. The hydrogels, as well as the respective injectable bone substitutes (IBSs), were fully characterized from the physical-chemical point of view. Weight change studies proved that all hydro...

  14. Virus-based piezoelectric energy generation.

    Science.gov (United States)

    Lee, Byung Yang; Zhang, Jinxing; Zueger, Chris; Chung, Woo-Jae; Yoo, So Young; Wang, Eddie; Meyer, Joel; Ramesh, Ramamoorthy; Lee, Seung-Wuk

    2012-05-13

    Piezoelectric materials can convert mechanical energy into electrical energy, and piezoelectric devices made of a variety of inorganic materials and organic polymers have been demonstrated. However, synthesizing such materials often requires toxic starting compounds, harsh conditions and/or complex procedures. Previously, it was shown that hierarchically organized natural materials such as bones, collagen fibrils and peptide nanotubes can display piezoelectric properties. Here, we demonstrate that the piezoelectric and liquid-crystalline properties of M13 bacteriophage (phage) can be used to generate electrical energy. Using piezoresponse force microscopy, we characterize the structure-dependent piezoelectric properties of the phage at the molecular level. We then show that self-assembled thin films of phage can exhibit piezoelectric strengths of up to 7.8 pm V(-1). We also demonstrate that it is possible to modulate the dipole strength of the phage, hence tuning the piezoelectric response, by genetically engineering the major coat proteins of the phage. Finally, we develop a phage-based piezoelectric generator that produces up to 6 nA of current and 400 mV of potential and use it to operate a liquid-crystal display. Because biotechnology techniques enable large-scale production of genetically modified phages, phage-based piezoelectric materials potentially offer a simple and environmentally friendly approach to piezoelectric energy generation.

  15. Virus-based piezoelectric energy generation

    Science.gov (United States)

    Lee, Byung Yang; Zhang, Jinxing; Zueger, Chris; Chung, Woo-Jae; Yoo, So Young; Wang, Eddie; Meyer, Joel; Ramesh, Ramamoorthy; Lee, Seung-Wuk

    2012-06-01

    Piezoelectric materials can convert mechanical energy into electrical energy, and piezoelectric devices made of a variety of inorganic materials and organic polymers have been demonstrated. However, synthesizing such materials often requires toxic starting compounds, harsh conditions and/or complex procedures. Previously, it was shown that hierarchically organized natural materials such as bones, collagen fibrils and peptide nanotubes can display piezoelectric properties. Here, we demonstrate that the piezoelectric and liquid-crystalline properties of M13 bacteriophage (phage) can be used to generate electrical energy. Using piezoresponse force microscopy, we characterize the structure-dependent piezoelectric properties of the phage at the molecular level. We then show that self-assembled thin films of phage can exhibit piezoelectric strengths of up to 7.8 pm V-1. We also demonstrate that it is possible to modulate the dipole strength of the phage, hence tuning the piezoelectric response, by genetically engineering the major coat proteins of the phage. Finally, we develop a phage-based piezoelectric generator that produces up to 6 nA of current and 400 mV of potential and use it to operate a liquid-crystal display. Because biotechnology techniques enable large-scale production of genetically modified phages, phage-based piezoelectric materials potentially offer a simple and environmentally friendly approach to piezoelectric energy generation.

  16. Subject-specific bone attenuation correction for brain PET/MR: can ZTE-MRI substitute CT scan accurately?

    Science.gov (United States)

    Khalifé, Maya; Fernandez, Brice; Jaubert, Olivier; Soussan, Michael; Brulon, Vincent; Buvat, Irène; Comtat, Claude

    2017-10-01

    In brain PET/MR applications, accurate attenuation maps are required for accurate PET image quantification. An implemented attenuation correction (AC) method for brain imaging is the single-atlas approach that estimates an AC map from an averaged CT template. As an alternative, we propose to use a zero echo time (ZTE) pulse sequence to segment bone, air and soft tissue. A linear relationship between histogram normalized ZTE intensity and measured CT density in Hounsfield units (HU ) in bone has been established thanks to a CT-MR database of 16 patients. Continuous AC maps were computed based on the segmented ZTE by setting a fixed linear attenuation coefficient (LAC) to air and soft tissue and by using the linear relationship to generate continuous μ values for the bone. Additionally, for the purpose of comparison, four other AC maps were generated: a ZTE derived AC map with a fixed LAC for the bone, an AC map based on the single-atlas approach as provided by the PET/MR manufacturer, a soft-tissue only AC map and, finally, the CT derived attenuation map used as the gold standard (CTAC). All these AC maps were used with different levels of smoothing for PET image reconstruction with and without time-of-flight (TOF). The subject-specific AC map generated by combining ZTE-based segmentation and linear scaling of the normalized ZTE signal into HU was found to be a good substitute for the measured CTAC map in brain PET/MR when used with a Gaussian smoothing kernel of 4~mm corresponding to the PET scanner intrinsic resolution. As expected TOF reduces AC error regardless of the AC method. The continuous ZTE-AC performed better than the other alternative MR derived AC methods, reducing the quantification error between the MRAC corrected PET image and the reference CTAC corrected PET image.

  17. Biological responses of brushite-forming Zn- and ZnSr- substituted beta-tricalcium phosphate bone cements.

    Science.gov (United States)

    Pina, S; Vieira, S I; Rego, P; Torres, P M C; da Cruz e Silva, O A B; da Cruz e Silva, E F; Ferreira, J M F

    2010-09-07

    The core aim of this study was to investigate zinc (Zn)- and zinc and strontium (ZnSr)-containing brushite-forming beta-tricalcium phosphate (TCP) cements for their effects on proliferation and differentiation of osteoblastic-like cells (MC3T3-E1 cell line) as well as for their in vivo behaviour in trabecular bone cylindrical defects in a pilot study. In vitro proliferation and maturation responses of MC3T3-E1 osteoblastic-like cells to bone cements were studied at the cellular and molecular levels. The Zn- and Sr-containing brushite cements were found to stimulate pre-osteoblastic proliferation and osteoblastic maturation. Indeed, MC3T3-E1 cells exposed to the powdered cements had increased proliferative rates and higher adhesiveness capacity, in comparison to control cells. Furthermore, they exhibited higher alkaline phosphatase (ALP) activity and increased Type-I collagen secretion and fibre deposition into the extracellular matrix. Proliferative and collagen deposition properties were more evident for cells grown in cements doped with Sr. The in vivo osteoconductive propertiesof the ZnCPC and ZnSrCPC cements were also pursued. Histological and histomorphometric analyses were performed at 1 and 2 months after implantation, using carbonated apatite cement (Norian SRS) as control. There was no evidence of cement-induced adverse foreign body reactions, and furthermore ZnCPC and ZnSrCPC cements revealed better in vivo performance in comparison to the control apatite cement. Additionally, the presence of both zinc and strontium resulted in the highest rate of new bone formation. These novel results indicate that the investigated ZnCPC and ZnSrCPC cements are both biocompatible and osteoconductive, being good candidate materials to use as bone substitutes.

  18. Biological responses of brushite-forming Zn- and ZnSr- substituted beta-tricalcium phosphate bone cements

    Directory of Open Access Journals (Sweden)

    S Pina

    2010-09-01

    Full Text Available The core aim of this study was to investigate zinc (Zn- and zinc and strontium (ZnSr-containing brushite-forming beta-tricalcium phosphate (TCP cements for their effects on proliferation and differentiation of osteoblastic-like cells (MC3T3-E1 cell line as well as for their in vivo behaviour in trabecular bone cylindrical defects in a pilot study. In vitro proliferation and maturation responses of MC3T3-E1 osteoblastic-like cells to bone cements were studied at the cellular and molecular levels. The Zn- and Sr-containing brushite cements were found to stimulate pre-osteoblastic proliferation and osteoblastic maturation. Indeed, MC3T3-E1 cells exposed to the powdered cements had increased proliferative rates and higher adhesiveness capacity, in comparison to control cells. Furthermore, they exhibited higher alkaline phosphatase (ALP activity and increased Type-I collagen secretion and fibre deposition into the extracellular matrix. Proliferative and collagen deposition properties were more evident for cells grown in cements doped with Sr. The in vivo osteoconductive propertiesof the ZnCPC and ZnSrCPC cements were also pursued. Histological and histomorphometric analyses were performed at 1 and 2 months after implantation, using carbonated apatite cement (Norian SRS® as control. There was no evidence of cement-induced adverse foreign body reactions, and furthermore ZnCPC and ZnSrCPC cements revealed better in vivo performance in comparison to the control apatite cement. Additionally, the presence of both zinc and strontium resulted in the highest rate of new bone formation. These novel results indicate that the investigated ZnCPC and ZnSrCPC cements are both biocompatible and osteoconductive, being good candidate materials to use as bone substitutes.

  19. Preparation and characterization of calcium phosphate ceramics and Composites as bone substitutes

    OpenAIRE

    Zhang, Xing

    2007-01-01

    Marine CaCO₃ skeletons have tailored architectures created by nature, which give them structural support and other functions. For example, seashells have dense lamellar structures, while coral, cuttlebone and sea urchin spines have interconnected porous structures. In our experiments, seashells, coral and cuttlebone were hydrothermally converted to hydroxyapatite (HAP), and sea urchin spines were converted to Mg-substituted tricalcium phosphate [beta]-TCMP, while maintaining their original st...

  20. In vitro performance assessment of new brushite-forming Zn- and ZnSr-substituted beta-TCP bone cements.

    Science.gov (United States)

    Pina, S; Vieira, S I; Torres, P M C; Goetz-Neunhoeffer, F; Neubauer, J; da Cruz E Silva, O A B; da Cruz E Silva, E F; Ferreira, J M F

    2010-08-01

    The present study investigated the in vitro performance of brushite-forming Zn- and ZnSr-substituted beta-TCP bone cements in terms of wet mechanical strength and biological response. Quantitative phase analysis and structural refinement of the powdered samples were performed by X-ray powder diffraction and Rietveld refinement technique. Initial and final setting times of the cement pastes, measured using Gilmore needles technique, showed that ZnSrCPC sets faster than ZnCPC. The measured values of the wet strength after 48 h of immersion in PBS solution at 37 degrees C showed that ZnSrCPC cements are stronger than ZnCPC cements. Human osteosarcoma-derived MG63 cell line proved the nontoxicity of the cement powders, using the resazurin metabolic assay.

  1. Porous calcium polyphosphate bone substitutes: additive manufacturing versus conventional gravity sinter processing-effect on structure and mechanical properties.

    Science.gov (United States)

    Hu, Youxin; Shanjani, Yaser; Toyserkani, Ehsan; Grynpas, Marc; Wang, Rizhi; Pilliar, Robert

    2014-02-01

    Porous calcium polyphosphate (CPP) structures proposed as bone-substitute implants and made by sintering CPP powders to form bending test samples of approximately 35 vol % porosity were machined from preformed blocks made either by additive manufacturing (AM) or conventional gravity sintering (CS) methods and the structure and mechanical characteristics of samples so made were compared. AM-made samples displayed higher bending strengths (≈1.2-1.4 times greater than CS-made samples), whereas elastic constant (i.e., effective elastic modulus of the porous structures) that is determined by material elastic modulus and structural geometry of the samples was ≈1.9-2.3 times greater for AM-made samples. X-ray diffraction analysis showed that samples made by either method displayed the same crystal structure forming β-CPP after sinter annealing. The material elastic modulus, E, determined using nanoindentation tests also showed the same value for both sample types (i.e., E ≈ 64 GPa). Examination of the porous structures indicated that significantly larger sinter necks resulted in the AM-made samples which presumably resulted in the higher mechanical properties. The development of mechanical properties was attributed to the different sinter anneal procedures required to make 35 vol % porous samples by the two methods. A primary objective of the present study, in addition to reporting on bending strength and sample stiffness (elastic constant) characteristics, was to determine why the two processes resulted in the observed mechanical property differences for samples of equivalent volume percentage of porosity. An understanding of the fundamental reason(s) for the observed effect is considered important for developing improved processes for preparation of porous CPP implants as bone substitutes for use in high load-bearing skeletal sites.

  2. Evaluation of bone substitutes for treatment of peri-implant bone defects: biomechanical, histological, and immunohistochemical analyses in the rabbit tibia

    Science.gov (United States)

    2016-01-01

    Purpose We sought to evaluate the effectiveness of bone substitutes in circumferential peri-implant defects created in the rabbit tibia. Methods Thirty rabbits received 45 implants in their left and right tibia. A circumferential bone defect (6.1 mm in diameter/4 mm depth) was created in each rabbit tibia using a trephine bur. A dental implant (4.1 mm × 8.5 mm) was installed after the creation of the defect, providing a 2-mm gap. The bone defect gaps between the implant and the bone were randomly filled according to the following groups: blood clot (CO), particulate Bio-Oss® (BI), and Bio-Oss® Collagen (BC). Ten animals were euthanized after periods of 15, 30, and 60 days. Biomechanical analysis by means of the removal torque of the implants, as well as histologic and immunohistochemical analyses for protein expression of osteocalcin (OC), Runx2, OPG, RANKL, and TRAP were evaluated. Results For biomechanics, BC showed a better biological response (61.00±15.28 Ncm) than CO (31.60±14.38 Ncm) at 30 days. Immunohistochemical analysis showed significantly different OC expression in CO and BC at 15 days, and also between the CO and BI groups, and between the CO and BC groups at 60 days. After 15 days, Runx2 expression was significantly different in the BI group compared to the CO and BC groups. RANKL expression was significantly different in the BI and CO groups and between the BI and BC groups at 15 days, and also between the BI and CO groups at 60 days. OPG expression was significantly higher at 60 days postoperatively in the BI group than the CO group. Conclusions Collectively, our data indicate that, compared to CO and BI, BC offered better bone healing, which was characterized by greater RUNX2, OC, and OPG immunolabeling, and required greater reversal torque for implant removal. Indeed, along with BI, BC presents promising biomechanical and biological properties supporting its possible use in osteoconductive grafts for filling peri-implant gaps. PMID:27382506

  3. 3D printing of mineral–polymer bone substitutes based on sodium alginate and calcium phosphate

    Science.gov (United States)

    Egorov, Aleksey A; Fedotov, Alexander Yu; Mironov, Anton V; Popov, Vladimir K; Zobkov, Yury V

    2016-01-01

    Summary We demonstrate a relatively simple route for three-dimensional (3D) printing of complex-shaped biocompatible structures based on sodium alginate and calcium phosphate (CP) for bone tissue engineering. The fabrication of 3D composite structures was performed through the synthesis of inorganic particles within a biopolymer macromolecular network during 3D printing process. The formation of a new CP phase was studied through X-ray diffraction, Fourier transform infrared spectroscopy and scanning electron microscopy. Both the phase composition and the diameter of the CP particles depend on the concentration of a liquid component (i.e., the “ink”). The 3D printed structures were fabricated and found to have large interconnected porous systems (mean diameter ≈800 μm) and were found to possess compressive strengths from 0.45 to 1.0 MPa. This new approach can be effectively applied for fabrication of biocompatible scaffolds for bone tissue engineering constructions. PMID:28144529

  4. Bioactive calcium sulfate/magnesium phosphate cement for bone substitute applications

    Energy Technology Data Exchange (ETDEWEB)

    Yang, Guangyong [Department of Orthopaedics, Taizhou Hospital of Zhejiang Province, Linhai Zhejiang, 317000 (China); Department of Orthopaedic Surgery, Second Affiliated Hospital of Wenzhou Medical College, Wenzhou, Zhejiang, 325000 (China); Liu, Jianli [Trauma Center, Affiliated Hospital of Hainan Medical University, Haikou, Hainan, 570206 (China); Division of Functional Materials and Nanodevices, Ningbo Institute of Materials Technology and Engineering (NIMTE), Chinese Academy of Sciences (CAS), Ningbo, Zhejiang, 315201 (China); Li, Fan; Pan, Zongyou; Ni, Xiao; Shen, Yue [Department of Orthopaedic Surgery, Second Affiliated Hospital of Wenzhou Medical College, Wenzhou, Zhejiang, 325000 (China); Xu, Huazi, E-mail: spinexu@163.com [Department of Orthopaedic Surgery, Second Affiliated Hospital of Wenzhou Medical College, Wenzhou, Zhejiang, 325000 (China); Huang, Qing, E-mail: huangqing@nimte.ac.cn [Division of Functional Materials and Nanodevices, Ningbo Institute of Materials Technology and Engineering (NIMTE), Chinese Academy of Sciences (CAS), Ningbo, Zhejiang, 315201 (China)

    2014-02-01

    A novel calcium sulfate/magnesium phosphate cement (CSMPC) composite was prepared and studied in the present work. The physical properties including the phases, the microstructures, the setting properties and the compressive strengths of the CSMPCs were studied. The bio-performances of the CSMPCs were comprehensively evaluated using in vitro simulated body fluid (SBF) method and in vitro cell culture. The dependence of the physical and chemical properties of the CSMPC on its composition and microstructure was studied in detail. It is found that the CSMPC composites exhibited mediate setting times (6–12 min) compared to the calcium sulfate (CS) and the magnesium phosphate cement (MPC). They showed an encapsulation structure in which the unconverted hexagonal prism CSH particles were embedded in the xerogel-like MPC matrix. The phase compositions and the mechanical properties of the CSMPCs were closely related to the content of MPC and the hardening process. The CSMPCs exhibited excellent bioactivity and good biocompatibility to support the cells to attach and proliferate on the surface. The CSMPC composite has the potential to serve as bone grafts for the bone regeneration. - Highlights: • The mechanical strength and degradation rate of CSMPC composites are discussed. • The CSMPC composites exhibited good bioactivity to form bone-like apatite. • The CSMPC composites also show good biocompatibility.

  5. Calcium sulphate as a bone substitute for various osseous defects in conjunction with apicectomy.

    Science.gov (United States)

    Murashima, Y; Yoshikawa, G; Wadachi, R; Sawada, N; Suda, H

    2002-09-01

    The purpose of this study was to investigate the effect of calcium sulphate on various osseous defects when used in conjunction with apicectomy. Mandibular third and fourth premolars of 11 beagle dogs were used. After root-canal treatment and apicectomy, three types of osseous defects were prepared on both sides of the mandible as follows: type 1, osseous defect communicating with the gingival sulcus: type 2, large osseous defect including two roots; type 3, 'through and through' osseous defect. The experimental side was allocated randomly, and the osseous defects were filled with medical grade calcium sulphate. The defects on the opposite side were left unfilled as controls. The dogs were sacrificed at 8 and 16 weeks postoperatively. Undemineralized sections were obtained and examined histomorphometrically. In type 1 defects, bone was not observed on the buccal side of the root on either experimental or control side at 8 and 16 weeks. In both type 2 and 3 defects, bone volume/tissue volume (BV/TV) values on the experimental side were significantly higher than those on the control side (P < 0.01), and mineral apposition rate (MAR) values on the experimental side were significantly higher than those on the control side (P < 0.01). The use of calcium sulphate was effective in bone regeneration on both large osseous defects and 'through and through' osseous defects. It was less effective in osseous defects communicating with the gingival sulcus.

  6. Enhanced temperature stability and quality factor with Hf substitution for Sn and MnO2 doping of (Ba0.97Ca0.03)(Ti0.96Sn0.04)O3 lead-free piezoelectric ceramics with high Curie temperature

    Science.gov (United States)

    Tsai, Cheng-Che; Chao, Wei-Hsiang; Chu, Sheng-Yuan; Hong, Cheng-Shong; Weng, Chung-Ming; Su, Hsiu-Hsien

    2016-12-01

    In this work, the process of two-stage modifications for (Ba0.97Ca0.03)(Ti0.96Sn0.04-xHfx)O3 (BCTS4-100xH100x) ceramics was studied. The trade-off composition was obtained by Hf substitution for Sn and MnO2 doping (two-stage modification) which improves the temperature stability and piezoelectric properties. The phase structure ratio, microstructure, and dielectric, piezoelectric, ferroelectric, and temperature stability properties were systematically investigated. Results showed that BCTS4-100xH100x piezoelectric ceramics with x=0.035 had a relatively high Curie temperature (TC) of about 112 °C, a piezoelectric charge constant (d33) of 313 pC/N, an electromechanical coupling factor (kp) of 0.49, a mechanical quality factor (Qm) of 122, and a remnant polarization (Pr) of 19 μ C /cm2 . In addition, the temperature stability of the resonant frequency (fr), kp, and aging d33 could be tuned via Hf content. Good piezoelectric temperature stability (up to 110 °C) was found with x =0.035. BCTS0.5H3.5 + a mol% Mn (BCTSH + a Mn) piezoelectric ceramics with a = 2 had a high TC of about 123 °C, kp ˜ 0.39, d33 ˜ 230 pC/N, Qm ˜ 341, and high temperature stability due to the produced oxygen vacancies. This mechanism can be depicted using the complex impedance analysis associated with a valence compensation model on electric properties. Two-stage modification for lead-free (Ba0.97Ca0.03)(Ti0.96Sn0.04)O3 ceramics suitably adjusts the compositions for applications in piezoelectric motors and actuators.

  7. Enhanced temperature stability and quality factor with Hf substitution for Sn and MnO2 doping of (Ba0.97Ca0.03(Ti0.96Sn0.04O3 lead-free piezoelectric ceramics with high Curie temperature

    Directory of Open Access Journals (Sweden)

    Cheng-Che Tsai

    2016-12-01

    Full Text Available In this work, the process of two-stage modifications for (Ba0.97Ca0.03(Ti0.96Sn0.04-xHfxO3 (BCTS4-100xH100x ceramics was studied. The trade-off composition was obtained by Hf substitution for Sn and MnO2 doping (two-stage modification which improves the temperature stability and piezoelectric properties. The phase structure ratio, microstructure, and dielectric, piezoelectric, ferroelectric, and temperature stability properties were systematically investigated. Results showed that BCTS4-100xH100x piezoelectric ceramics with x=0.035 had a relatively high Curie temperature (TC of about 112 °C, a piezoelectric charge constant (d33 of 313 pC/N, an electromechanical coupling factor (kp of 0.49, a mechanical quality factor (Qm of 122, and a remnant polarization (Pr of 19μC/cm2. In addition, the temperature stability of the resonant frequency (fr, kp, and aging d33 could be tuned via Hf content. Good piezoelectric temperature stability (up to 110 °C was found with x =0.035. BCTS0.5H3.5 + a mol% Mn (BCTSH + a Mn piezoelectric ceramics with a = 2 had a high TC of about 123 °C, kp ∼ 0.39, d33 ∼ 230 pC/N, Qm ∼ 341, and high temperature stability due to the produced oxygen vacancies. This mechanism can be depicted using the complex impedance analysis associated with a valence compensation model on electric properties. Two-stage modification for lead-free (Ba0.97Ca0.03(Ti0.96Sn0.04O3 ceramics suitably adjusts the compositions for applications in piezoelectric motors and actuators.

  8. Graft Remodeling following Transcrestal Sinus Floor Elevation via the Gel-Pressure Technique (GPT and Pasteous Nano-Crystalline Hydroxyapatite Bone Substitute

    Directory of Open Access Journals (Sweden)

    Bernhard Pommer

    2015-06-01

    Full Text Available Bone grafting of the maxillary sinus is attempted to compensate for sinus pneumatization and permit reliable insertion of endosseous dental implants for prosthetic rehabilitation. The aim of the present clinical investigation was to study bone regeneration four months after transcrestal sinus floor elevation via the Gel-Pressure Technique (GPT and application of pasteous nano-crystalline hydroxyapatite bone substitute. A total of 25 patients with deficient alveolar ridges in the posterior maxilla (mean residual bone height: 4.7 ± 1.8 mm were subjected to 32 flapless transcrestal sinus floor augmentations and simultaneous insertion of 40 implants. Sinus membrane elevation height averaged 11.2 ± 2.7 mm and minimal vertical graft resorption of 0.1 mm was observed after four months. Radiographic bone density averaged 460 Hounsfield units in regions adjacent to the native jawbone (1 to 7 mm distance, while reduction of bone density by −7.2%, −11.3%, −14.8%, −19.6% and −22.7% was recorded in more apical regions of 8, 9, 10, 11, and ≥12 mm distance to the original sinus floor, respectively. The results suggest that graft remodeling is completed up to a distance of 7 mm within a healing period of four months after sinus augmentation using nano-crystalline hydroxyapatite bone substitute material.

  9. SU-C-213-01: 3D Printed Patient Specific Phantom Composed of Bone and Soft Tissue Substitute Plastics for Radiation Therapy

    Energy Technology Data Exchange (ETDEWEB)

    Ehler, E; Sterling, D; Higgins, P [University of Minnesota, Minneapolis, MN (United States)

    2015-06-15

    Purpose: 3D printed phantoms constructed of multiple tissue approximating materials could be useful in both clinical and research aspects of radiotherapy. This work describes a 3D printed phantom constructed with tissue substitute plastics for both bone and soft tissue; air cavities were included as well. Methods: 3D models of an anonymized nasopharynx patient were generated for air cavities, soft tissues, and bone, which were segmented by Hounsfield Unit (HU) thresholds. HU thresholds were chosen to define air-to-soft tissue boundaries of 0.65 g/cc and soft tissue-to-bone boundaries of 1.18 g/cc based on clinical HU to density tables. After evaluation of several composite plastics, a bone tissue substitute was identified as an acceptable material for typical radiotherapy x-ray energies, composed of iron and PLA plastic. PET plastic was determined to be an acceptable soft tissue substitute. 3D printing was performed on a consumer grade dual extrusion fused deposition model 3D printer. Results: MVCT scans of the 3D printed heterogeneous phantom were acquired. Rigid image registration of the patient and the 3D printed phantom scans was performed. The average physical density of the soft tissue and bone regions was 1.02 ± 0.08 g/cc and 1.39 ± 0.14 g/cc, respectively, for the patient kVCT scan. In the 3D printed phantom MVCT scan, the average density of the soft tissue and bone was 1.01 ± 0.09 g/cc and 1.44 ± 0.12 g/cc, respectively. Conclusion: A patient specific phantom, constructed of heterogeneous tissue substitute materials was constructed by 3D printing. MVCT of the 3D printed phantom showed realistic tissue densities were recreated by the 3D printing materials. Funding provided by intra-department grant by University of Minnesota Department of Radiation Oncology.

  10. Bioactive calcium sulfate/magnesium phosphate cement for bone substitute applications.

    Science.gov (United States)

    Yang, Guangyong; Liu, Jianli; Li, Fan; Pan, Zongyou; Ni, Xiao; Shen, Yue; Xu, Huazi; Huang, Qing

    2014-02-01

    A novel calcium sulfate/magnesium phosphate cement (CSMPC) composite was prepared and studied in the present work. The physical properties including the phases, the microstructures, the setting properties and the compressive strengths of the CSMPCs were studied. The bio-performances of the CSMPCs were comprehensively evaluated using in vitro simulated body fluid (SBF) method and in vitro cell culture. The dependence of the physical and chemical properties of the CSMPC on its composition and microstructure was studied in detail. It is found that the CSMPC composites exhibited mediate setting times (6-12 min) compared to the calcium sulfate (CS) and the magnesium phosphate cement (MPC). They showed an encapsulation structure in which the unconverted hexagonal prism CSH particles were embedded in the xerogel-like MPC matrix. The phase compositions and the mechanical properties of the CSMPCs were closely related to the content of MPC and the hardening process. The CSMPCs exhibited excellent bioactivity and good biocompatibility to support the cells to attach and proliferate on the surface. The CSMPC composite has the potential to serve as bone grafts for the bone regeneration.

  11. Effect of a Bone Graft Substitute β Tricalcium Phosphate on Osteoblastic Genes mRNA Exprssion

    Institute of Scientific and Technical Information of China (English)

    QIU Tong; WANG Youfa; HAN Yinchao; JIANG Xin; LI Shipu

    2012-01-01

    To investigate the molecular aspects of osteoblastic interactions with β tricalcium phosphate (β-TCP) particles,human osteoblast-like MG-63 cells were cultured with β-TCP particles at a density of 6 mg/mL culture medium for 48 h.Then,the mRNA expression of selected genes were quantified by realtime polymerase chain reaction (PCR),including the attachment-related genes (α integrin and actin),the proliferation-related gene (c-jun),and the osteoblastic markers genes (type Ⅰ collagen,osteonectin,alkaline phosphatase,RUNX2 and osteoclain).The results showed that β-TCP particles (the average size 809 nm)significantly promote the attachment and the proliferation of MG-63 cells,and slightly enhance the osteoblastic differentiation based on the analyses of the related genes expression.This study provided scientific evidences to better reveal the underlines of functions of β-TCP in bone repair.

  12. Histological and histomorphometrical analysis of a silica matrix embedded nanocrystalline hydroxyapatite bone substitute using the subcutaneous implantation model in Wistar rats

    Energy Technology Data Exchange (ETDEWEB)

    Ghanaati, Shahram; Orth, Carina; Barbeck, Mike; Kirkpatrick, Charles James [Institute of Pathology, University Medical Center of the Johannes Gutenberg University Mainz, Langenbeckstrasse 1, 55101 Mainz (Germany); Willershausen, Ines [Institute for Dental Material Sciences and Technology, University Medical Center of the Johannes Gutenberg University Mainz, Anselm-Franz-von-Bentzel-Weg 14, 55128 Mainz (Germany); Thimm, Benjamin W [Institute for Biomechanics, ETH Zuerich, Wolfgang-Pauli-Str.10, 8093 Zuerich (Switzerland); Booms, Patrick [Leeds Institute of Molecular Medicine, Section of Medicine, Surgery and Anaesthesia, University of Leeds (United Kingdom); Stuebinger, Stefan; Landes, Constantin; Sader, Robert Anton, E-mail: ghanaati@uni-mainz.d [Department for Oral, Cranio-Maxillofacial and Facial Plastic Surgery, Medical Center of the Goethe University Frankfurt, Theodor-Stein-Kai 7, 60596 Frankfurt am Main (Germany)

    2010-06-01

    The clinical suitability of a bone substitute material is determined by the ability to induce a tissue reaction specific to its composition. The aim of this in vivo study was to analyze the tissue reaction to a silica matrix-embedded, nanocrystalline hydroxyapatite bone substitute. The subcutaneous implantation model in Wistar rats was chosen to assess the effect of silica degradation on the vascularization of the biomaterial and its biodegradation within a time period of 6 months. Already at day 10 after implantation, histomorphometrical analysis showed that the vascularization of the implantation bed reached its peak value compared to all other time points. Both vessel density and vascularization significantly decreased until day 90 after implantation. In this time period, the bone substitute underwent a significant degradation initiated by TRAP-positive and TRAP-negative multinucleated giant cells together with macrophages and lymphocytes. Although no specific tissue reaction could be related to the described silica degradation, the biomaterial was close to being fully degraded without a severe inflammatory response. These characteristics are advantageous for bone regeneration and remodeling processes.

  13. Guideline update for the performance of fusion procedures for degenerative disease of the lumbar spine. Part 16: bone graft extenders and substitutes as an adjunct for lumbar fusion.

    Science.gov (United States)

    Kaiser, Michael G; Groff, Michael W; Watters, William C; Ghogawala, Zoher; Mummaneni, Praveen V; Dailey, Andrew T; Choudhri, Tanvir F; Eck, Jason C; Sharan, Alok; Wang, Jeffrey C; Dhall, Sanjay S; Resnick, Daniel K

    2014-07-01

    In an attempt to enhance the potential to achieve a solid arthrodesis and avoid the morbidity of harvesting autologous iliac crest bone (AICB) for a lumbar fusion, numerous alternatives have been investigated. The use of these fusion adjuncts has become routine despite a lack of convincing evidence demonstrating a benefit to justify added costs or potential harm. Potential alternatives to AICB include locally harvested autograft, calcium-phosphate salts, demineralized bone matrix (DBM), and the family of bone morphogenetic proteins (BMPs). In particular, no option has created greater controversy than the BMPs. A significant increase in the number of publications, particularly with respect to the BMPs, has taken place since the release of the original guidelines. Both DBM and the calciumphosphate salts have demonstrated efficacy as a graft extender or as a substitute for AICB when combined with local autograft. The use of recombinant human BMP-2 (rhBMP-2) as a substitute for AICB, when performing an interbody lumbar fusion, is considered an option since similar outcomes have been observed; however, the potential for heterotopic bone formation is a concern. The use of rhBMP-2, when combined with calcium phosphates, as a substitute for AICB, or as an extender, when used with local autograft or AICB, is also considered an option as similar fusion rates and clinical outcomes have been observed. Surgeons electing to use BMPs should be aware of a growing body of literature demonstrating unique complications associated with the use of BMPs.

  14. Bone graft substitutes for the treatment of traumatic fractures of the extremities [Knochenersatzmaterialien zur Behandlung von traumatischen Frakturen der Extremitäten

    Directory of Open Access Journals (Sweden)

    Hagen, Anja

    2012-06-01

    Full Text Available [english] Bone graft substitutes are increasingly being used as supplements to standard care or as alternative to bone grafts in the treatment of traumatic fractures.The efficacy and cost-effectiveness of bone graft substitutes for the treatment of traumatic fractures as well as the ethical, social and legal implications of their use are the main research questions addressed.A systematic literature search was conducted in electronic medical databases (MEDLINE, EMBASE etc. in December 2009. Randomised controlled trials (RCT, where applicable also containing relevant health economic evaluations and publications addressing the ethical, social and legal aspects of using bone graft substitutes for fracture treatment were included in the analysis. After assessment of study quality the information synthesis of the medical data was performed using metaanalysis, the synthesis of the health economic data was performed descriptively. 14 RCT were included in the medical analysis, and two in the heath economic evaluation. No relevant publications on the ethical, social and legal implications of the bone graft substitute use were found. In the RCT on fracture treatment with bone morphogenetic protein-2 (BMP-2 versus standard care without bone grafting (RCT with an elevd high risk of bias there was a significant difference in favour of BMP-2 for several outcome measures. The RCT of calcium phosphate (CaP cement and bone marrow-based composite materials versus autogenous bone grafts (RCT with a high risk of bias revealed significant differences in favour of bone graft substitutes for some outcome measures. Regarding the other bone graft substitutes, almost all comparisons demonstrated no significant difference.The use of BMP-2 in addition to standard care without bone grafting led in the study to increased treatment costs considering all patients with traumatic open fractures. However, cost savings through the additional use of BMP-2 were calculated in a

  15. Bone marrow transplantation from unrelated donors: the impact of mismatches with substitutions at position 116 of the human leukocyte antigen class I heavy chain.

    Science.gov (United States)

    Ferrara, G B; Bacigalupo, A; Lamparelli, T; Lanino, E; Delfino, L; Morabito, A; Parodi, A M; Pera, C; Pozzi, S; Sormani, M P; Bruzzi, P; Bordo, D; Bolognesi, M; Bandini, G; Bontadini, A; Barbanti, M; Frumento, G

    2001-11-15

    The hypothesis was tested that amino acid substitutions in specific positions within human leukocyte antigen class I heavy chain would have different impacts on transplant-related mortality (TRM) in patients receiving transplanted bone marrow from unrelated donors. One hundred patients and their unrelated donors were typed by sequence-based typing for the human leukocyte antigen (HLA)-A, -B, and -C loci. All pairs were matched for DRB1, DRB3, DRB4, DRB5, DQA1, and DQB1 loci. Forty pairs were also matched at class I, and 60 pairs had one or more mismatches at class I loci. It was found that substitutions at positions 116 and 114 of class I heavy chain significantly increased the risk for TRM in univariate and bivariate Cox analyses. Conversely, no association between number of multiple mismatches or number of amino acid substitutions and TRM was seen when positions 116 and 114 were adjusted for. Variables predictive of TRM in multivariate Cox analysis were number of cells infused, diagnosis (chronic myeloid leukemia [CML] or non-CML), and amino acid substitution at position 116 or 152. The only variable predictive of severe acute graft-versus-host disease (GVHD) in multivariate Cox analysis was substitution at position 116. Actuarial risk for acute GVHD grade III-IV, TRM, and relapse in pairs with substitutions at position 116 (n = 37) compared to other pairs (n = 63) was, respectively, 36% versus 14% (P =.01), 59% versus 28% (P =.001), and 25% versus 31% (P =.4). In conclusion these data suggest that substitutions at position 116 of class I heavy chain increase the risk for acute GVHD and TRM in patients who receive transplanted bone marrow from unrelated donors.

  16. Comparison of three calcium phosphate bone graft substitutes from biomechanical, histological, and crystallographic perspectives using a rat posterolateral lumbar fusion model.

    Science.gov (United States)

    Hu, Ming-Hsien; Lee, Pei-Yuan; Chen, Wen-Cheng; Hu, Jin-Jia

    2014-12-01

    This study evaluated the effectiveness of three calcium phosphate bone graft substitutes with different chemical compositions on spinal fusion using a rat posterolateral lumbar fusion model. Specifically, two recently developed non-dispersive tetracalcium phosphate/dicalcium phosphate anhydrous-based calcium phosphate cements (CPCs), namely a CPC consisting of equimolar amounts of the two compounds (nd-CPC) and a CPC consisting of a two-fold greater amount of dicalcium phosphate anhydrous (DCP-rich CPC), were compared with a commercial calcium phosphate bone graft (c-CPG) consisting of hydroxyapatite (60%) and β-tricalcium phosphate (40%). Single-level posterolateral lumbar fusion was performed at the L4-L5 vertebrae in fifteen adult rats (n=5 for each group). Spinal fusion was evaluated with radiographs, manual palpation, mechanical testing, micro-CT, and histology 8 weeks post-surgery. In particular, the crystallographic phases in the three substitutes were identified before and 8 weeks after their implantation. Manual palpation revealed stable constructs in nearly all of the spine specimens. The stiffness and bending load of fused spines in the two CPC groups were comparable to those in the c-CPG group. The radiographs specifically revealed implant resorption and bone remodeling in the DCP-rich CPC group. Analysis of 3D micro-CT images revealed that the bone volume ratio in the DCP-rich CPC group was significantly greater than those in the nd-CPC and c-CPG groups. Histology showed that the DCP-rich CPC group exhibited the highest degree of bone regeneration and osseointegration. Notably, DCP-rich CPC led to a pronounced phase transformation, generating the greatest amount of poorly crystalline apatite among the three groups, which together with adequate resorption may explain the aforementioned positive findings. We therefore conclude that of the bone graft substitutes considered, DCP-rich CPC has the greatest potential to be used in spinal fusion.

  17. Biofabrication of a PLGA-TCP-based porous bioactive bone substitute with sustained release of icaritin.

    Science.gov (United States)

    Xie, Xin-Hui; Wang, Xin-Luan; Zhang, Ge; He, Yi-Xin; Leng, Yang; Tang, Ting-Ting; Pan, Xiaohua; Qin, Ling

    2015-08-01

    A phytomolecule, icaritin, has been identified and shown to be osteopromotive for the prevention of osteoporosis and osteonecrosis. This study aimed to produce a bioactive poly (l-lactide-co-glycolide)-tricalcium phosphate (PLGA-TCP)-based porous scaffold incorporating the osteopromotive phytomolecule icaritin, using a fine spinning technology. Both the structure and the composition of icaritin-releasing PLGA-TCP-based scaffolds were evaluated by scanning electron microscopy (SEM). The porosity was quantified by both water absorption and micro-computed tomography (micro-CT). The mechanical properties were evaluated using a compression test. In vitro release of icaritin from the PLGA-TCP scaffold was quantified by high-performance liquid chromatography (HPLC). The attachment, proliferation and osteogenic differentiation of bone marrow mesenchymal stem cells (BMSCs) on the composite scaffold were evaluated. Both an in vitro cytotoxicity test and an in vivo test via muscular implantation were conducted to confirm the scaffold's biocompatibility. The results showed that the PLGA-TCP-icaritin composite scaffold was porous, with interconnected macro- (about 480 µm) and micropores (2-15 µm). The mechanical properties of the PLGA-TCP-icaritin scaffold were comparable with those of the pure PLGA-TCP scaffold, yet was spinning direction-dependent. Icaritin content was detected in the medium and increased with time. The PLGA-TCP-icaritin scaffold facilitated the attachment, proliferation and osteogenic differentiation of BMSCs. In vitro cytotoxicity test and in vivo intramuscular implantation showed that the composite scaffold had no toxicity with good biocompatibility. In conclusion, an osteopromotive phytomolecule, icaritin, was successfully incorporated into PLGA-TCP to form an innovative porous composite scaffold with sustained release of osteopromotive icaritin, and this scaffold had good biocompatibility and osteopromotion, suggesting its potential for orthopaedic

  18. Estudio experimental de la osteosustitución con biomateriales cerámicos formulados como cementos óseos Experimental study of the bone substitution with ceramic biomaterials formulated as bone cements

    Directory of Open Access Journals (Sweden)

    E S Sanzana

    2007-01-01

    Full Text Available Los biomateriales cerámicos presentan interesantes propiedades biológicas, por lo que pueden ser utilizados en la sustitución ósea. En este estudio fueron comparados dos cementos óseos de fosfato de calcio con el autoinjerto óseo esponjoso. Se realizó un defecto cavitario de 6 mm en la metáfisis femoral distal derecha de 36 conejos machos Oryctolagus cuniculi. Los animales fueron divididos en 3 grupos de 12 conejos, que recibieron como implantes cemento de fosfato a tricálcico (TPC, cemento de fosfato monocálcico (MPC y autoinjerto óseo (CON. Los estudios radiológico e histológico han mostrado una correcta sustitución de ambos biomateriales por hueso neoformado. El estudio histomorfométrico ha revelado que la neoformación ósea obtenida con los 2 cementos, tanto a las 4 como las 12 semanas, es equivalente a la generada por el injerto óseo. No se han encontrado diferencias significativas en la reabsorción de los materiales. Finalmente, este trabajo ha concluido que los cementos óseos de fosfato de calcio son materiales osteoconductivos, osteotransductivos y biocompatibles que se comportan como sustitutivos óseos.Ceramic biomaterials have interesting biological properties that can be used in bone substitution. In this study two calcium phosphate bone cements were compared to cancellous bone autograft. A bone cavitary defect of 6 mm in diameter was carried out in the right distal femoral methaphyses of 36 male rabbits Oryctolagus cuniculi. The animals were divided into 3 groups of 12 rabbits receiving a tricalcium phosphate cement (TPC, monocalcium phosphate cement (MPC and autologous bone (CON as implants. The radiological and histological studies showed a correct substitution of both biomaterials with new bone. The histomorphometric study revealed that the bone neoformation obtained with the two cements at 4 and 12 weeks is equivalent to the bone generated by the bone graft. There were no significant differences in the

  19. Piezoelectric surgery in implant dentistry: clinical applications

    Directory of Open Access Journals (Sweden)

    Lydia Masako Ferreira

    2009-01-01

    Full Text Available Pizosurgery has therapeutic characteristics in osteotomies, such as extremely precise, selective and millimetric cuts and a clear operating field. Piezoelectricity uses ultrasonic frequencies, which cause the points specially designed for osteotomy to vibrate. The points of the instrument oscillate, allowing effective osteotomy with minimal or no injury to the adjacent soft tissues, membranes and nerve tissues. This article presents the various applications of piezoelectricity in oral implant surgery such as: removal of autogenous bone; bone window during elevation of the sinus membrane and removal of fractured implants. The cavitational effect caused by the vibration of the point and the spray of physiological solution, provided a field free of bleeding and easy to visualize. The study showed that the piezoelectric surgery is a new surgical procedurethat presents advantages for bone cutting in many situations in implant dentistry, with great advantages in comparison with conventional instrumentation. Operating time is longer when compared with that of conventional cutters.

  20. Piezoelectric particle accelerator

    Energy Technology Data Exchange (ETDEWEB)

    Kemp, Mark A.; Jongewaard, Erik N.; Haase, Andrew A.; Franzi, Matthew

    2017-08-29

    A particle accelerator is provided that includes a piezoelectric accelerator element, where the piezoelectric accelerator element includes a hollow cylindrical shape, and an input transducer, where the input transducer is disposed to provide an input signal to the piezoelectric accelerator element, where the input signal induces a mechanical excitation of the piezoelectric accelerator element, where the mechanical excitation is capable of generating a piezoelectric electric field proximal to an axis of the cylindrical shape, where the piezoelectric accelerator is configured to accelerate a charged particle longitudinally along the axis of the cylindrical shape according to the piezoelectric electric field.

  1. Comparison of three calcium phosphate bone graft substitutes from biomechanical, histological, and crystallographic perspectives using a rat posterolateral lumbar fusion model

    Energy Technology Data Exchange (ETDEWEB)

    Hu, Ming-Hsien [Department of Biomedical Engineering, National Cheng Kung University, Tainan 701, Taiwan (China); Department of Orthopedics, Show-Chwan Memorial Hospital, Changhua 50544, Taiwan (China); Department of Orthopedic Surgery, Faculty of Medicine, National Yang-Ming University, Taipei 112, Taiwan (China); Lee, Pei-Yuan [Department of Biomedical Engineering, National Cheng Kung University, Tainan 701, Taiwan (China); Department of Orthopedics, Show-Chwan Memorial Hospital, Changhua 50544, Taiwan (China); Chen, Wen-Cheng, E-mail: wincheng0925@yahoo.com.tw [Department of Fiber and Composite Materials, College of Engineering, Feng Chia University, Taichung 40724, Taiwan (China); Hu, Jin-Jia, E-mail: jjhu@mail.ncku.edu.tw [Department of Biomedical Engineering, National Cheng Kung University, Tainan 701, Taiwan (China); Medical Device Innovation Center, National Cheng Kung University, Tainan 701, Taiwan (China)

    2014-12-01

    This study evaluated the effectiveness of three calcium phosphate bone graft substitutes with different chemical compositions on spinal fusion using a rat posterolateral lumbar fusion model. Specifically, two recently developed non-dispersive tetracalcium phosphate/dicalcium phosphate anhydrous-based calcium phosphate cements (CPCs), namely a CPC consisting of equimolar amounts of the two compounds (nd-CPC) and a CPC consisting of a two-fold greater amount of dicalcium phosphate anhydrous (DCP-rich CPC), were compared with a commercial calcium phosphate bone graft (c-CPG) consisting of hydroxyapatite (60%) and β-tricalcium phosphate (40%). Single-level posterolateral lumbar fusion was performed at the L4–L5 vertebrae in fifteen adult rats (n = 5 for each group). Spinal fusion was evaluated with radiographs, manual palpation, mechanical testing, micro-CT, and histology 8 weeks post-surgery. In particular, the crystallographic phases in the three substitutes were identified before and 8 weeks after their implantation. Manual palpation revealed stable constructs in nearly all of the spine specimens. The stiffness and bending load of fused spines in the two CPC groups were comparable to those in the c-CPG group. The radiographs specifically revealed implant resorption and bone remodeling in the DCP-rich CPC group. Analysis of 3D micro-CT images revealed that the bone volume ratio in the DCP-rich CPC group was significantly greater than those in the nd-CPC and c-CPG groups. Histology showed that the DCP-rich CPC group exhibited the highest degree of bone regeneration and osseointegration. Notably, DCP-rich CPC led to a pronounced phase transformation, generating the greatest amount of poorly crystalline apatite among the three groups, which together with adequate resorption may explain the aforementioned positive findings. We therefore conclude that of the bone graft substitutes considered, DCP-rich CPC has the greatest potential to be used in spinal fusion

  2. Piezoelectric Motors, an Overview

    OpenAIRE

    Karl Spanner; Burhanettin Koc

    2016-01-01

    Piezoelectric motors are used in many industrial and commercial applications. Various piezoelectric motors are available in the market. All of the piezoelectric motors use the inverse piezoelectric effect, where microscopically small oscillatory motions are converted into continuous or stepping rotary or linear motions. Methods of obtaining long moving distance have various drive and functional principles that make these motors categorized into three groups: resonance-drive (piezoelectric ult...

  3. [Bone substitutes augmentation combined with internal fixation versus internal fixation alone in treating proximal femoral fractures in the elderly: a meta-analysis].

    Science.gov (United States)

    Wu, Jian-bin; Yang, Lei; Zhou, Fei-ya; Feng, Yong-zeng

    2016-06-01

    To systematically review the effectiveness of bone substitute augmentation combined with internal fixation versus internal fixation alone in treating proximal femoral fractures in the elderly. Subject term and keywords were searched from Pubmed, Cochrane databases and CNKI from database foundation to August 2015. Randomized controlled studies and qusi-randomized controlled studies on bone substitutes augmentation combined with internal fixation versus internal fixation alone for the treatment of proximal femoral fractures in the elderly were chosen. Postoperative re-displacement, re-operation rate, complications (infection and bone ununion), functional outcome, quality of life scores and muscle strength were seen as outcome indicators. Enumeration data were statistical analyzed by risk difference and 95% confidence interval. Measurement data were analyzed by standardized mean difference and 95% confidence interval. If the same measurement data were evaluated by different standards in different studies, standardized mean differences and 95% confidence interval were used. The methods of statistical analysis were used by Cochrane databases. Eleven RCTs (677 patients) were included. Meta-analysis results indicated that bone substitutes augmentation combined with internal fixation occurred fewer re-displacement [SMD = -0.75, 95% CI (-1.03, -0.47)] and obtained better function [SMD = 0.40, 95% CI (0.20, 0.59)]. While there were no significant differences in reoperation rate [RD = 0.02, 95% CI (-0.05, -0.09)], pain at 1 week after operation [MD = -1.79, 95% CI (-13.55, -9.96)], pain ranged from 6 to 8 weeks [MD = -7.24, 95% CI (-20.07, -5.59)], postoperative pain at 12 weeks [MD = -0.32, 95% CI (-4.9, -3.55)], muscle strength [MD = 1.25, 95% CI (-6.98, -9.48)], bone ununion [RD = 0.02, 95% CI (-0.01, -0.05)] and postoperative complications [MD = 0.01, 95% CI (-0.03, -0.04)]. Compared with single internal fixation, bone substitutes augmentation combined with internal

  4. Complex reconstruction of the dorsal hand using the induced membrane technique associated with bone substitute: A case report

    Directory of Open Access Journals (Sweden)

    Vivien Moris

    2015-12-01

    Conclusion: The induced membrane technique allowed the reconstruction of small bone deficits in the long bones of the hand in a two-step procedure, the first step taking place in an emergency context of composite tissue trauma.

  5. Strontium- and cobalt-substituted bioactive glasses seeded with human umbilical cord perivascular cells to promote bone regeneration via enhanced osteogenic and angiogenic activities.

    Science.gov (United States)

    Kargozar, Saeid; Lotfibakhshaiesh, Nasrin; Ai, Jafar; Mozafari, Masoud; Brouki Milan, Peiman; Hamzehlou, Sepideh; Barati, Mahmood; Baino, Francesco; Hill, Robert G; Joghataei, Mohammad Taghi

    2017-08-01

    Designing and developing new biomaterials to accelerate bone healing are currently under progress. In this study, we attempted to promote osteogenesis using strontium- and cobalt-substituted bioactive glasses (BGs) seeded with human umbilical cord perivascular cells (HUCPVCs) in a critical size defect in the distal femur of rabbit animal model. The BG particles were successfully synthesized in the form of granules using the melt-derived route. After being isolated, HUCPVCs were expanded and then characterized to use during in vitro and in vivo procedures. The in vitro effects of the synthesized glasses on the isolated HUCPVCs as well as on cell lines SaOS-2 (selected for screening the osteogenetic potential) and HUVEC (selected for screening the angiogenic potential) were assessed by analyzing cytotoxicity, cell attachment, bone-like nodule formation, and real time PCR. The results of in vitro tests indicated cytocompatibility of the synthesized BG particles. For in vivo study, the HUCPVCs-seeded BGs were implanted into the animal's body. Radiographic imaging, histology and immunohistology staining were performed on the harvested specimens at 4 and 12weeks post-surgery. The in vivo evaluation of the samples showed that all the cell/glass constructs accelerated bone healing process in comparison with blank controls. The best in vitro and in vivo results were associated to the BGs containing both strontium and cobalt ions. This group of bioactive glasses is able to promote both osteogenesis and angiogenesis and can therefore be highly suitable for the development of advanced functional bone substitutes. Bone regeneration is considered as an unmet clinical need. The most recent researches focused on incorporation of strontium (Sr(2+)) and cobalt (Co(2+)) ions into bioactive glasses structure. Strontium is an alkaline earth metal which is currently used in the treatment of osteoporosis. Also, cobalt is considered as another promising element in the bone regeneration

  6. [Hydroxyapatite bone substitute (Ostim) in sinus floor elevation. Maxillary sinus floor augmentation: bone regeneration by means of a nanocrystalline in-phase hydroxyapatite (Ostim)].

    Science.gov (United States)

    Smeets, Ralf; Grosjean, Maurice B; Jelitte, Gerd; Heiland, Max; Kasaj, Adrian; Riediger, Dieter; Yildirim, Murat; Spiekermann, Hubertus; Maciejewski, Oliver

    2008-01-01

    The range of bone regeneration materials suitable for maxillar bone augmentation has increased steadily in the past few years and there is now a wide variety of materials being used. In the present case report, we analyzed the state of bone regeneration after sinus floor augmentation using a nanocrystalline in-phase synthetic anorganic hydroxyapatite bone grafting material (Ostim). A 60-year-old female patient underwent maxillary sinus floor elevation and the cavity was filled with Ostim three years before. Actually, she presented herself with loosening of the dental implant at position 17, as a result of parafunction. At the time of the insertion of a second implant at position 17, bone samples were taken by using a trepan drilling device from the previously augmented area. These samples were analyzed histologically to determine the extent of bone remodeling around the deposits of Ostim. We found that the Ostim deposits were surrounded largely by woven bone and, in parts, by lamellar bone and had facilitated osteoconductive bone regeneration. The adjacent implant, at position 16, which beared a crown exposed to proper biting forces without parafunction, showed proper clinical and radiological characteristics of complete and firm integration into the area which was also filled with Ostim three years ago. We conclude that the use of the nanocrystalline hydroxyapatite Ostim with its stable volume properties appears to be suitable for maxillary sinus floor augmentation. Furthermore, we even found osteoconductive bone regeneration under Ostim near the site of the loosened implant.

  7. Calcium Phosphates as Bone Substitute for Dental Implant Surgery%口腔种植中磷酸钙类骨替代材料的应用

    Institute of Scientific and Technical Information of China (English)

    陈卓凡; 刘泉; Matinlinna JP

    2016-01-01

    在口腔种植手术中,磷酸钙类的骨替代材料已经被广泛应用于骨修复、骨增量和重建.了解此类材料的基础性能,对于一个种植医生来说是非常重要的,但初学者可能无法完全掌握.因此,本文对异种来源和人工合成的两类骨移植材料的特点,进行了全面总结评述.尽管部分材料显示了优良的生物效应,但目前磷酸钙类的骨替代材料仍有巨大的改进提升空间.%Calcium phosphate-based bone substitutes have been widely used for bone repair, augmentation and recon-struction in dental implant surgery. The basic properties of such materials are undoubtedly of importance, but may not be comprehensively understood by practitioners. Hence, the properties of two major groups, xenogenic and alloplastic grafting materials, have been reviewed and discussed in this article. It appears that more work is needed to improve the perfor-mance of the current calcium phosphate-based bone substitutes, although some of them have been showing outstanding bi-ological response.

  8. Effect of a carbonated HAP/β-glucan composite bone substitute on healing of drilled bone voids in the proximal tibial metaphysis of rabbits

    Energy Technology Data Exchange (ETDEWEB)

    Borkowski, Leszek, E-mail: leszek.borkowski@umlub.pl [Department of Biochemistry and Biotechnology, Medical University of Lublin, Chodźki 1, 20-093 Lublin (Poland); Pawłowska, Marta; Radzki, Radosław P.; Bieńko, Marek [Department of Animal Physiology, University of Life Sciences in Lublin, Akademicka 12, 20-033 Lublin (Poland); Polkowska, Izabela [Department and Clinic of Animal Surgery, University of Life Sciences in Lublin, Głęboka 30, 20-612 Lublin (Poland); Belcarz, Anna [Department of Biochemistry and Biotechnology, Medical University of Lublin, Chodźki 1, 20-093 Lublin (Poland); Karpiński, Mirosław [Department of Companion and Wildlife Animals, University of Life Sciences in Lublin, Akademicka 13, 20-950 Lublin (Poland); Słowik, Tymoteusz [Independent Radiology Unit at Lublin Small Animals Medical Centre, Stefczyka 11, 20-151 Lublin (Poland); Matuszewski, Łukasz [Children' s Orthopaedic Clinic and Rehabilitation Department, Medical University of Lublin, Chodzki 2, 20-093 Lublin (Poland); Ślósarczyk, Anna [Faculty of Materials Science and Ceramics, AGH-University of Science and Technology, Mickiewicza 30, 30-059 Krakow (Poland); Ginalska, Grażyna [Department of Biochemistry and Biotechnology, Medical University of Lublin, Chodźki 1, 20-093 Lublin (Poland)

    2015-08-01

    A novel elastic hydroxyapatite-based composite of high surgical handiness has been developed. Its potential application in orthopedics as a filler of bone defects has been studied. The biomaterial was composed of carbonated hydroxyapatite (CHAP) granules and polysaccharide polymer (β-1,3-glucan). Cylinders of 4 mm in diameter and 6 mm in length were implanted into bone cavities created in the proximal metaphysis of tibiae of 24 New Zealand white rabbits. 18 sham-operated animals were used as controls. After 1, 3 or 6 months, the rabbits were euthanized, the bones were harvested and subjected to analysis. Radiological images and histological sections revealed integration of implants with bone tissue with no signs of graft rejection. Peripheral quantitative computed tomography (pQCT) indicated the stimulating effect of the biomaterial on bone formation and mineralization. Densitometry (DXA) analysis suggested that biomineralization of bones was preceded by bioresorption and gradual disappearance of porous ceramic granules. The findings suggest that the CHAP–glucan composite material enables regeneration of bone tissue and could serve as a bone defect filler. - Highlights: • Highly porous carbonate HAP granules and β-1,3-glucan were used to fill bone voids. • Critical size defects of rabbit tibiae were filled with the composite scaffolds. • Biocompatibility, mineralization and osseointegration of implants were examined. • Histological analysis indicated a high biocompatibility of composite grafts. • We report penetration of bony tissue into implants and advanced osseointegration.

  9. A scintigraphic study of composited bone substitute in the repair of bone defect of femoral head%复合人工骨修复股骨头骨缺损的影像学研究

    Institute of Scientific and Technical Information of China (English)

    同志勤; 徐小良; 王坤正; 宋厂义

    2001-01-01

    Objective To evaluate the effect of bBMP-collagen-coral composited bone substitute in treatment of osteonecrosis of the femoral head(ONFH).Methods Canine bone defect of bilateral femoral head was established,They were devided into 4 groups:Ⅰ.composited bone substitute group(n=5),Ⅱ.muscle pedicle bone group (n=5),Ⅲ.simple coral group(n=4),Ⅳ.control group:contralateral hip(n=14).Roentgenography,Scintigraphy,MRI,CT were examined and studied at various time.Results ①Scintigraphic changes:In group Ⅰ,static bone image showed increased radionuclide uptake,but blood flow and blood-pool image didn't show in 6 and 12 week;②MRI:There was much more new bone formation in the bone defect of group Ⅰ;In group Ⅳ,there was fatty bone marrow which was surrounded with sclerotic bone;③Resules of roentgenographic and CT:In 14-16 weeks,in group Ⅰ,the coral was absorbed and most of the bone defects were closed completely;In the rest groups,part of each bone defect was remained except that in group Ⅳ,cystic sclerosis was formed.Conclusion The composited bone substitute possesses a superior osteoinductivity and osteoconductivity in the repair of bone defect of femoral head,but it can't improve the revascularization of ONFH.%目的研究用复合人工骨治疗股骨头坏死的效果。方法建立双侧股骨头内骨缺损模型,并分为4组:bBMP-胶原-珊瑚复合人工骨组(5侧)、肌骨瓣组(5侧)、单纯珊瑚组(4侧)、对照组(14侧,为以上各组的对侧)。造模及植入后定时行X线、核素骨显像、MRI及CT检查。结果①核素骨显像示:6周及12周,Ⅰ组股骨头核素摄取量静态相头/干比升高,但血流相及血池相不升高。②MRI:10周示Ⅰ组骨缺损内多量新生骨形成,Ⅳ组骨缺损内囊腔中为脂肪性信号,周围为低信号的硬化带。③拍片及CT示:14~16周,Ⅰ组骨缺损大多完全闭合,珊瑚已吸收,其余各组骨缺损部分残

  10. Biological evaluation of alginate-based hydrogels, with antimicrobial features by Ce(III) incorporation, as vehicles for a bone substitute.

    Science.gov (United States)

    Morais, D S; Rodrigues, M A; Lopes, M A; Coelho, M J; Maurício, A C; Gomes, R; Amorim, I; Ferraz, M P; Santos, J D; Botelho, C M

    2013-09-01

    A novel hydrogel, based on an alginate/hyaluronate mixture and Ce(III) ions, with effective bioactive and antimicrobial ability was developed to be used as vehicle of a synthetic bone substitute producing an injectable substitute (IBS). Firstly, three different IBSs were prepared using three developed alginate-based hydrogels, the hydrogel Alg composed by alginate, the hydrogel Alg/Ch composed by an alginate/chitosan mixture and the hydrogel Alg/HA composed by an alginate/hyaluronate mixture. MG63 cells viability on the IBSs was evaluated, being observed a significantly higher cell viability on the Alg/HA_IBS at all time points, which indicates a better cell adaptation to the material, increasing their predisposition to produce extracellular matrix and thus allowing a better bone regeneration. Moreover, SEM analysis showed evident filopodia and a spreader shape of MG63 cells when seeded on Alg/HA_IBS. This way, based upon the in vitro results, the hydrogel Alg/HA was chosen to the in vivo study by subcutaneous implantation in an animal model, promoting a slight irritating tissue response and visible tissue repairing. The next step was to grant antimicrobial properties to the hydrogel that showed the best biological behavior by incorporation of Ce(III) ions into the Alg/HA, producing the hydrogel Alg/HA2. The antimicrobial activity of these hyaluronate-based hydrogels was evaluated against Staphylococcus aureus, Staphylococcus epidermidis, Pseudomonas aeruginosa and Candida albicans. Results showed that Ce(III) ions can significantly enhance the hydrogel antimicrobial ability without compromising the osteoconductivity improvement promoted by the vehicle association to the synthetic bone substitute.

  11. Defect Engineering of Lead-Free Piezoelectrics with High Piezoelectric Properties and Temperature-Stability.

    Science.gov (United States)

    Feng, Yu; Li, Wei-Li; Xu, Dan; Qiao, Yu-Long; Yu, Yang; Zhao, Yu; Fei, Wei-Dong

    2016-04-13

    The high piezoelectricity of ABO3-type lead-free piezoelectric materials can be achieved with the help of either morphotropic phase boundary (MPB) or polymorphic phase transition (PPT). Here, we propose a new defect engineering route to the excellent piezoelectric properties, in which doped smaller acceptor and donor ions substituting bivalent A-sites are utilized to bring local lattice distortion and lower symmetry. A concrete paradigm is presented, (Li-Al) codoped BaTiO3 perovskite, that exhibits a largely thermo-stable piezoelectric constant (>300 pC/N) and huge mechanical quality factor (>2000). A systematic analysis including theoretical analysis and simulation results indicates that the Li(+) and Al(3+) ions are inclined to occupy the neighboring A-sites in the lattice and constitute a defect dipole (ionic pairs). The defect dipoles possess a kind of dipole moment which tends to align directionally after thermo-electric treatment. A mechanism related to the defect symmetry principle, phase transition, and defect migration is proposed to explain the outstanding piezoelectric properties. The present study opens a new development window for excellent piezoelectricity and provides a promising route to the potential utilization of lead-free piezoelectrics in high power applications.

  12. Piezoelectric drive circuit

    Science.gov (United States)

    Treu, Jr., Charles A.

    1999-08-31

    A piezoelectric motor drive circuit is provided which utilizes the piezoelectric elements as oscillators and a Meacham half-bridge approach to develop feedback from the motor ground circuit to produce a signal to drive amplifiers to power the motor. The circuit automatically compensates for shifts in harmonic frequency of the piezoelectric elements due to pressure and temperature changes.

  13. Bone

    Science.gov (United States)

    Helmberger, Thomas K.; Hoffmann, Ralf-Thorsten

    The typical clinical signs in bone tumours are pain, destruction and destabilization, immobilization, neurologic deficits, and finally functional impairment. Primary malignant bone tumours are a rare entity, accounting for about 0.2% of all malignancies. Also benign primary bone tumours are in total rare and mostly asymptomatic. The most common symptomatic benign bone tumour is osteoid osteoma with an incidence of 1:2000.

  14. Evaluation of cell binding peptide (p15) with silk fibre enhanced hydroxyappatite bone substitute for posterolateral spinal fusion in sheep

    DEFF Research Database (Denmark)

    Axelsen, M.; Jespersen, Stig; Overgaard, Søren

    2015-01-01

    on the surface of bone forming cells. The binding initiates natural intra- and extracellular signalling pathways, inducing production of growth factors, bone morphogenic proteins and cytokines. P15 peptide has previously shown to improve osteoinductive properties when coated on graft materials. Purpose...

  15. Osteogenic protein-1 increases the fixation of implants grafted with morcellised bone allograft and ProOsteon bone substitute: an experimental study in dogs

    DEFF Research Database (Denmark)

    Baad-Hansen, Thomas Einer; Overgaard, S; Lind, M;

    2007-01-01

    (ProOsteon) would improve the incorporation of bone and implant fixation. We also compared the response to using ProOsteon alone against bone allograft used in isolation. We implanted two non-weight-bearing hydroxyapatite-coated implants into each proximal humerus of six dogs, with each implant...... surrounded by a concentric 3 mm gap. These gaps were randomly allocated to four different procedures in each dog: 1) bone allograft used on its own; 2) ProOsteon used on its own; 3) allograft and ProOsteon used together; or 4) allograft and ProOsteon with the addition of osteogenic protein-1. After three...

  16. Effects of Li Substitution and Sintering Temperature on Properties of Bi0.5(Na,K)0.5TiO3 Lead-Free Piezoelectric Ceramics

    Institute of Scientific and Technical Information of China (English)

    MING Bao-Quan; WANG Jin-Feng; ZANG Guo-Zhong

    2008-01-01

    Bi0.5 (Na0.72K0.28-xLix)0.5 TiO3 (BNKLT-100x) lead-free piezoelectric ceramics are synthesized by conventional solid state sintering techniques. The dielectric and piezoelectric properties of the BNKLT-100x ceramics as a function of Li content are systematically investigated. It is found that not only Li content but also the sintering temperature has a strong effect on the piezoelectric properties of BNKLT. The piezoelectric constant d33 of BNKLT varies from 120 to 252pC/N in the Li content range from 0.03 to 0.16. In the sintering temperature range from 1080 to 1130℃, the d33 value of BNKLT-6 changes from 200pC/N to 252pC/N. The BNKLT-6 sample sintered at 1100℃ has the highest piezoelectric constant d33 Of 252pC/N, with the electromechanical coupling factors kp of 0.32 and kt of 0.44.

  17. Piezoelectric technology for pediatric autologous cranioplasty.

    Science.gov (United States)

    Phillips, Benjamin Z; Taylor, Helena O; Klinge, Petra M; Sullivan, Stephen R

    2014-05-01

    Objective : Pediatric patients with skull defects larger than available sources for splitting bicortical bone have limited options for autogenous cortical bone cranioplasty. Piezoelectric instruments allow donor bone to be chosen based on the best possible contour rather than the presence of bicortical bone. We present the use of piezoelectric technology to split thin unicortical calvarium for autogenous cranioplasty in a series of pediatric patients. Design : Retrospective review of a series of pediatric patients requiring reconstruction for skull defects. Patients/Intervention : Our series included a 2-year-old with a parietal skull tumor and resultant 3 × 3-cm defect after craniectomy, a 2-year-old with a 3 × 3-cm defect after excision of an occipital skull tumor, a 10-year-old with a 4 × 5-cm skull defect after excision of an occipital skull tumor, and a 13-year-old who suffered a gunshot to the forehead with a 12 × 7-cm frontal skull defect. We used a piezoelectric saw to precisely and safely split unicortical and bicortical cranium that ranged from 1 to 3 mm in thickness. The inner layer was used to reconstruct the donor site; whereas, the outer layer was used for the craniectomy defect. Conclusion : The piezoelectric saw allows unicortical bone to be split and used for cortical bone cranioplasty. This technology allows choice of donor site based on the best contour rather than the presence of bicortical bone. This technique expands the possibilities of autogenous cranioplasty and enables primary repair of cranial defects that would otherwise require secondary cranioplasty with remote donor sites, foreign materials, or unstable particulate cranioplasty.

  18. Piezoelectric Motors, an Overview

    Directory of Open Access Journals (Sweden)

    Karl Spanner

    2016-02-01

    Full Text Available Piezoelectric motors are used in many industrial and commercial applications. Various piezoelectric motors are available in the market. All of the piezoelectric motors use the inverse piezoelectric effect, where microscopically small oscillatory motions are converted into continuous or stepping rotary or linear motions. Methods of obtaining long moving distance have various drive and functional principles that make these motors categorized into three groups: resonance-drive (piezoelectric ultrasonic motors, inertia-drive, and piezo-walk-drive. In this review, a comprehensive summary of piezoelectric motors, with their classification from initial idea to recent progress, is presented. This review also includes some of the industrial and commercial applications of piezoelectric motors that are presently available in the market as actuators.

  19. Behavior of POP-calcium carbonate hydrogel as bone substitute with controlled release capability: a study in rat.

    Science.gov (United States)

    Dewi, Anne Handrini; Ana, Ika Dewi; Wolke, Joop; Jansen, John

    2015-10-01

    Gypsum or calcium sulfate (CS) or plaster of Paris (POP) is considered as a fast degradable material that usually resorbs before the bone defect area is completely filled by new bone. In this study, the incorporation of CaCO3 hydrogel into POP in different compositions was proposed to enhance the bone biological activity of POP and to decrease its degradability. The mechanical and degradation properties of the various materials were characterized by in vitro analysis. Subsequently, the materials were inserted into cylindrically sized bone defects as created into the femoral condyle of rats and left in situ for 1, 4, and 8 weeks. Histological analysis of the retrieved specimens indicated that the addition of CaCO3 hydrogel into POP increased bone formation, angiogenesis and collagen density and resulted into faster bone formation and maturation. It was also confirmed that the degradation rate of the POP decreased by the addition of CaCO3 hydrogel. The in vivo findings did corroborate with the in vitro analysis. In conclusion, the incorporation of CaCO3 hydrogel provides a promising technology to improve the properties of POP, the oldest biomaterial used for bone grafting. © 2015 Wiley Periodicals, Inc.

  20. Evaluation of bone substitute materials: comparison of flat-panel based volume CT to conventional multidetector CT.

    Science.gov (United States)

    Sauerbier, Sebastian; Duttenhoefer, Fabian; Sachlos, Elefterios; Haberstroh, Jörg; Scheifele, Christian; Wrbas, Karl-Thomas; Voss, Pit Jacob; Veigel, Egle; Smedek, Jörg; Ganter, Philip; Tuna, Taskin; Gutwald, Ralf; Palmowski, Moritz

    2013-10-01

    Over the last decade tissue engineering has emerged as a key factor in bone regeneration within the field of cranio-maxillofacial surgery. Despite this in vivo analysis of tissue-engineered-constructs to monitor bone rehabilitation are difficult to conduct. Novel high-resolving flat-panel based volume CTs (fp-VCT) are increasingly used for imaging bone structures. This study compares the potential value of novel fp-VCT with conventional multidetector CT (MDCT) based on a sheep sinus floor elevation model. Calcium-hydroxyapatite reinforced collagen scaffolds were populated with autologous osteoblasts and implanted into sheep maxillary sinus. After 8, 16 and 24 weeks MDCT and fp-VCT scans were performed to investigate the volume of the augmented area; densities of cancellous and compact bone were assessed as comparative values. fp-VCT imaging resulted in higher spatial resolution, which was advantageous when separating closely related anatomical structures (i.e. trabecular and compact bone, biomaterials). Fp-VCT facilitated imaging of alterations occurring in test specimens over time. fp-VCTs therefore displayed high volume coverage, dynamic imaging potential and superior performance when investigating superfine bone structures and bone remodelling of biomaterials. Thus, fp-VCTs may be a suitable instrument for intraoperative imaging and future in vivo tissue-engineering studies.

  1. Complex reconstruction of the dorsal hand using the induced membrane technique associated with bone substitute: A case report

    Science.gov (United States)

    Guillier, David; Rizzi, Philippe; De Taddeo, Alice; Henault, Benoit; Tchurukdichian, Alain; Zwetyenga, Narcisse

    2016-01-01

    Introduction High-energy trauma of the hand often causes tissue loss involving bone, tendon and skin and is sometimes accompanied by devascularization of digits. Bone stabilization is the first step in the management of such injuries. Materials and methods A young patient presented composite tissue loss of the dorsum of his right (dominant) hand following an accident with a surface planer. Tissue loss involved the diaphyses of the first 4 metacarpals, tendons and skin with almost complete amputation of the 3rd finger. Bone stabilization comprised osteosynthesis using pins associated with cement to fill the bone defect. Hunter tendon rods were used for tendon repair and a pedicle groin flap (McGregor) was used to achieve skin coverage. The cement was replaced with autologous cortico-cancellous bone graft combined with bone paste (Nanostim) 3 months after the cement stabilization. Results Eleven months after the accident, the patient was able to return to work as a carpenter. Pinch and Grasp strength in the injured hand were half that in the contralateral hand, but there was no loss of sensitivity. Mobility was very satisfactory with a Kapandji score of 9 and a mean TAM of 280°. The patient can write, open a bottle and does not feel limited for everyday activities. Radiographically, the bone of the 3 reconstructed metacarpals appears consolidated. Conclusion The induced membrane technique allowed the reconstruction of small bone deficits in the long bones of the hand in a two-step procedure, the first step taking place in an emergency context of composite tissue trauma. PMID:27077131

  2. Efficacy of a small cell-binding peptide coated hydroxyapatite substitute on bone formation and implant fixation in sheep

    DEFF Research Database (Denmark)

    Ding, Ming; Andreasen, Christina Møller; Dencker, Mads L.;

    2015-01-01

    hydroxyapatite (ABM/P-15); hydroxyapatite + βtricalciumphosphate+ Poly-Lactic-Acid (HA/βTCP-PDLLA); or ABM/P-15+HA/βTCP-PDLLA. After nine weeks, bone-implant blocks were harvested and sectioned for micro-CT scanning, push-out test, and histomorphometry. Significant bone formation and implant fixation could...... implant were not significantly different among the four groups. The ABM/P-15 group had similar shear mechanical properties on implant fixation as the allograft group. Adding HA/βTCP-PDLLA to ABM/P-15 did not significantly change these parameters. This study revealed that ABM/P-15 had significantly bone...

  3. A new surgical management for oro-antral communication: the resorbable guided tissue regeneration membrane--bone substitute sandwich technique.

    Science.gov (United States)

    Ogunsalu, C

    2005-09-01

    This paper describes a new technique for the closure of oro-antral fistula/communication, in which both hard tissue (bone) and soft tissue closure is achieved. The sandwich technique utilizes a suitable bone grafting material sandwiched between two sheaths of Biogide (a resorbable membrane) for the hard tissue closure of oro-antral communication post traumatic exodontia. The bone grafting material utilized for this case was Bio-oss. The result obtained was excellent with regeneration of sufficient bony tissue to allow placement of an endosseous implant. This sandwich technique is a simple and excellent technique for the closure of oro-antral communication, especially when subsequent placement of endosseous implant is considered without the need of donor site surgery for bone grafting. The otorhinolaryngologists and oral and maxillofacial surgeons should find this technique very useful in the closure of oro-antral fistulae.

  4. Fusion rate and clinical outcome in anterior lumbar interbody fusion with beta-tricalcium phosphate and bone marrow aspirate as a bone graft substitute. A prospective clinical study in fifty patients.

    Science.gov (United States)

    Lechner, Ricarda; Putzer, David; Liebensteiner, Michael; Bach, Christian; Thaler, Martin

    2017-02-01

    Bone graft substitutes have been successfully used in posterolateral lumbar fusion, anterior cervical fusion and animal studies. This study has been conducted to assess the safety and efficacy of β-tricalcium phosphate (β-TCP) in instrumented anterior lumbar interbody fusion (ALIF) procedure. In a prospective clinical study, ALIF cages were prefilled with β-TCP and additionally fixated with posterior pedicle screw. Computed tomography (CT) and X-rays were performed one year after surgery. Fusion was assessed and functional status was evaluated before and one year after surgery. X-ray evaluation showed a definite fusion in 85.48 % of treated levels. CT assessment showed anterior and posterior intersegemental bone bridging in 77.78 % of treated levels. The X-ray fusion rate presented is comparable with those published for ALIF procedures with bone graft. Fusion rates β-TCP are similar to autologous bone. ALIF with β-TCP and additional posterior fixation is a safe and effective procedure.

  5. Magnetic hydroxyapatite bone substitutes to enhance tissue regeneration: evaluation in vitro using osteoblast-like cells and in vivo in a bone defect.

    Directory of Open Access Journals (Sweden)

    Silvia Panseri

    Full Text Available In case of degenerative disease or lesion, bone tissue replacement and regeneration is an important clinical goal. In particular, nowadays, critical size defects rely on the engineering of scaffolds that are 3D structural supports, allowing cellular infiltration and subsequent integration with the native tissue. Several ceramic hydroxyapatite (HA scaffolds with high porosity and good osteointegration have been developed in the past few decades but they have not solved completely the problems related to bone defects. In the present study we have developed a novel porous ceramic composite made of HA that incorporates magnetite at three different ratios: HA/Mgn 95/5, HA/Mgn 90/10 and HA/Mgn 50/50. The scaffolds, consolidated by sintering at high temperature in a controlled atmosphere, have been analysed in vitro using human osteoblast-like cells. Results indicate high biocompatibility, similar to a commercially available HA bone graft, with no negative effects arising from the presence of magnetite or by the use of a static magnetic field. HA/Mgn 90/10 was shown to enhance cell proliferation at the early stage. Moreover, it has been implanted in vivo in a critical size lesion of the rabbit condyle and a good level of histocompatibility was observed. Such results identify this scaffold as particularly relevant for bone tissue regeneration and open new perspectives for the application of a magnetic field in a clinical setting of bone replacement, either for magnetic scaffold fixation or magnetic drug delivery.

  6. The effect of water, various incorporations and substitutions on physical and chemical properties of bioapatite and mechanical properties of bone tissue

    Directory of Open Access Journals (Sweden)

    A. S. Avrunin

    2015-01-01

    Full Text Available Basing on scientific publications and original research the authors specified the effect of incorporation and adsorption of different ions and water molecules on physical, chemical and mechanical properties of bioapatite and determined new directions for investigations of intercrystallite interactions in nanoscale. Inner structure of the apatite crystallites more adaptable to chemical substitutions in comparison with other minerals controls their important characteristics such as a size, solubility, hardness, fragility, formability and thermal stability. The water molecules incorporated in crystallites and adsorbed on their surfaces stabilize them. In case the distances between crystallites become shorter than 10 nm the water molecules adsorbed on their surface play dominant role in bonding between the crystallites. This bond determines the main mechanical properties of bones. We bring forward a suggestion that theoretical model developed on the basis of near edge X-ray spectroscopic studies of bones using the contemporary high brilliant sources of X-ray radiation (synchrotrons and X-ray free electrons lasers will allow to receive new quantitative data on local electronic and atomic structure (coordination numbers, ionic charges, interatomic distances interatomic and intercrystallite forces of nanoelements in osseous tissue. The investigation results must bring to construction of new morphologically correct model providing deeper understanding of processes occurring in mineral matrix and mechanical properties of bones.

  7. A piezoelectric transformer

    Science.gov (United States)

    Won, C. C.

    1993-01-01

    This work describes a modeling and design method whereby a piezoelectric system is formulated by two sets of second-order equations, one for the mechanical system, and the other for the electrical system, coupled through the piezoelectric effect. The solution to this electromechanical coupled system gives a physical interpretation of the piezoelectric effect as a piezoelectric transformer that is a part of the piezoelectric system, which transfers the applied mechanical force into a force-controlled current source, and short circuit mechanical compliance into capacitance. It also transfers the voltage source into a voltage-controlled relative velocity input, and free motional capacitance into mechanical compliance. The formulation and interpretation simplify the modeling of smart structures and lead to physical insight that aids the designer. Due to its physical realization, the smart structural system can be unconditional stable and effectively control responses. This new concept has been demonstrated in three numerical examples for a simple piezoelectric system.

  8. Piezoelectric Wheel System

    Science.gov (United States)

    Juang, Puu-An

    2007-10-01

    A piezoelectric wheel system is proposed for used as a microstepping displacement device including a carrier and two displacement members, which are separately pivoted on the carrier. Each displacement member includes two wheels, and which can not rotate. In addition, each wheel includes a wheel sheet and a piezoelectric element embedded on its surface. When the piezoelectricity element generates and transmits power to the wheel sheet, the wheel induces vibration and deformation. Therefore, owing to the wheel sheets and the touched ground involving their relative motion, the displacement device can be moved or can be oriented its motion direction. The wheel system involves direct movement, and has no rotor requirement. In this research, a three-dimensional (3D) mechanical element with an extra electrical degree of freedom is employed to simulate the dynamic vibration modes of the linear piezoelectric, mechanical, and piezoelectric-mechanical behaviours of the piezoelectric wheel.

  9. Piezoelectric energy harvesting

    CERN Document Server

    Erturk, Alper

    2011-01-01

    The transformation of vibrations into electric energy through the use of piezoelectric devices is an exciting and rapidly developing area of research with a widening range of applications constantly materialising. With Piezoelectric Energy Harvesting, world-leading researchers provide a timely and comprehensive coverage of the electromechanical modelling and applications of piezoelectric energy harvesters. They present principal modelling approaches, synthesizing fundamental material related to mechanical, aerospace, civil, electrical and materials engineering disciplines for vibration-

  10. Advanced Mechanics of Piezoelectricity

    CERN Document Server

    Qin, Qing-Hua

    2013-01-01

    "Advanced Mechanics of Piezoelectricity" presents a comprehensive treatment of piezoelectric materials using linear electroelastic theory, symplectic models, and Hamiltonian systems. It summarizes the current state of practice and presents the most recent research findings in piezoelectricity. It is intended for researchers and graduate students in the fields of applied mechanics, material science and engineering, computational engineering, and aerospace engineering. Dr. Qinghua Qin is a professor at the School of Engineering, Australian National University, Australia.

  11. Hybrid thermoelectric piezoelectric generator

    Science.gov (United States)

    Montgomery, D. S.; Hewitt, C. A.; Carroll, D. L.

    2016-06-01

    This work presents an integration of flexible thermoelectric and piezoelectric materials into a single device structure. This device architecture overcomes several prohibitive issues facing the combination of traditional thermoelectric and piezoelectric generators, while optimizing performance of the combined power output. The structure design uses a carbon nanotube/polymer thin film as a flexible thermoelectric generator that doubles as an electrode on a piezoelectric generator made of poly(vinylidene fluoride). An example 2 × 2 array of devices is shown to generate 89% of the maximum thermoelectric power, and provide 5.3 times more piezoelectric voltage when compared with a traditional device.

  12. Histological Study on a Novel Bone Graft Substitute: Human Derived Tooth-Hydroxyapatite Compared With Coralline Hydroxyapatite

    Science.gov (United States)

    2007-11-02

    HCl, Eczacýbaþý, Ýstanbul, Turkey). After anesthesia the tibial section of the right leg was shaved and disinfected. Under sterile surgical...conditions after incising the skin, the muscles and periost were dissected. The spongious bone medially at the proximal metaphysis of the tibia was

  13. Selenium-Substituted Hydroxyapatite/Biodegradable Polymer/Pamidronate Combined Scaffold for the Therapy of Bone Tumour.

    Science.gov (United States)

    Oledzka, Ewa; Sobczak, Marcin; Kolmas, Joanna; Nalecz-Jawecki, Grzegorz

    2015-09-14

    The present study evaluated a new concept of combined scaffolds as a promising bone replacement material for patients with a bone tumour or bone metastasis. The scaffolds were composed of hydroxyapatite doped with selenium ions and a biodegradable polymer (linear or branched), and contained an active substance-bisphosphonate. For this purpose, a series of biodegradable polyesters were synthesized through a ring-opening polymerization of ε-caprolactone or d,l-lactide in the presence of 2-hydroxyethyl methacrylate (HEMA) or hyperbranched 2,2-bis(hydroxymethyl)propionic acid polyester-16-hydroxyl (bis-MPA) initiators, substances often used in the synthesis of medical materials. The polymers were obtained with a high yield and a number-average molecular weight up to 45,300 (g/mol). The combined scaffolds were then manufactured by a direct compression of pre-synthesized hydroxyapatite doped with selenite or selenate ions, obtained polymer and pamidronate as a model drug. It was found that the kinetic release of the drug from the scaffolds tested in vitro under physiological conditions is strongly dependent on the physicochemical properties and average molecular weight of the polymers. Furthermore, there was good correlation with the hydrolytic biodegradation results of the scaffolds fabricated without drug. The preliminary findings suggest that the fabricated combined scaffolds could be effectively used for the sustained delivery of bioactive molecules at bone defect sites.

  14. Selenium-Substituted Hydroxyapatite/Biodegradable Polymer/Pamidronate Combined Scaffold for the Therapy of Bone Tumour

    Directory of Open Access Journals (Sweden)

    Ewa Oledzka

    2015-09-01

    Full Text Available The present study evaluated a new concept of combined scaffolds as a promising bone replacement material for patients with a bone tumour or bone metastasis. The scaffolds were composed of hydroxyapatite doped with selenium ions and a biodegradable polymer (linear or branched, and contained an active substance—bisphosphonate. For this purpose, a series of biodegradable polyesters were synthesized through a ring-opening polymerization of ε-caprolactone or d,l-lactide in the presence of 2-hydroxyethyl methacrylate (HEMA or hyperbranched 2,2-bis(hydroxymethylpropionic acid polyester-16-hydroxyl (bis-MPA initiators, substances often used in the synthesis of medical materials. The polymers were obtained with a high yield and a number-average molecular weight up to 45,300 (g/mol. The combined scaffolds were then manufactured by a direct compression of pre-synthesized hydroxyapatite doped with selenite or selenate ions, obtained polymer and pamidronate as a model drug. It was found that the kinetic release of the drug from the scaffolds tested in vitro under physiological conditions is strongly dependent on the physicochemical properties and average molecular weight of the polymers. Furthermore, there was good correlation with the hydrolytic biodegradation results of the scaffolds fabricated without drug. The preliminary findings suggest that the fabricated combined scaffolds could be effectively used for the sustained delivery of bioactive molecules at bone defect sites.

  15. Effects of altered crystalline structure and increased initial compressive strength of calcium sulfate bone graft substitute pellets on new bone formation.

    Science.gov (United States)

    Urban, Robert M; Turner, Thomas M; Hall, Deborah J; Infanger, Susan I; Cheema, Naveed; Lim, Tae-Hong; Moseley, Jon; Carroll, Michael; Roark, Michael

    2004-01-01

    A new, modified calcium sulfate has been developed with a different crystalline structure and a compressive strength similar to many calcium phosphate materials, but with a resorption profile only slightly slower than conventional surgical-grade calcium sulfate. A canine bilateral defect model was used to compare restoration of defects treated with the modified calcium sulfate compared to treatment using conventional calcium sulfate pellets after 6, 13, and 26 weeks. The modified calcium sulfate pellets were as effective as conventional calcium sulfate pellets with regard to the area fraction and compressive strength of newly formed bone in the treated bone defects. Mechanical testing demonstrated that the initial compressive strength of the modified material was increased nearly three-fold compared to that of conventional surgical-grade calcium sulfate. This increase potentially allows for its use in a broader range of clinical applications, such as vertebral and subchondral defects.

  16. Collagen-embedded hydroxylapatite-beta-tricalcium phosphate-silicon dioxide bone substitute granules assist rapid vascularization and promote cell growth

    Energy Technology Data Exchange (ETDEWEB)

    Ghanaati, Shahram M; Thimm, Benjamin W; Unger, Ronald E; Orth, Carina; Barbeck, Mike; Kirkpatrick, C James [Institute of Pathology, Johannes Gutenberg-University Mainz, Langenbeckstr.1, 55101 Mainz (Germany); Kohler, Thomas; Mueller, Ralph, E-mail: ghanaati@uni-mainz.d [Institute for Biomechanics, ETH Zuerich, Wolfgang-Pauli-Str.10, 8093 Zuerich (Switzerland)

    2010-04-15

    In the present study we assessed the biocompatibility in vitro and in vivo of a low-temperature sol-gel-manufactured SiO{sub 2}-based bone graft substitute. Human primary osteoblasts and the osteoblastic cell line, MG63, cultured on the SiO{sub 2} biomatrix in monoculture retained their osteoblastic morphology and cellular functionality in vitro. The effect of the biomaterial in vivo and its vascularization potential was tested subcutaneously in Wistar rats and demonstrated both rapid vascularization and good integration within the peri-implant tissue. Scaffold degradation was progressive during the first month after implantation, with tartrate-resistant acid phosphatase-positive macrophages being present and promoting scaffold degradation from an early stage. This manuscript describes successful osteoblastic growth promotion in vitro and a promising biomaterial integration and vasculogenesis in vivo for a possible therapeutic application of this biomatrix in future clinical studies.

  17. A novel {sup 99m}Tc-labeled dimethyl-substituted zoledronic acid (DMIDP) with improved bone imaging efficiency

    Energy Technology Data Exchange (ETDEWEB)

    Qiu, L.; Lin, J.; Luo, S.; Wang, Y.; Cheng, W.; Zhang, S. [Jiangsu Institute of Nuclear Medicine, Wuxi (China). Key Laboratory of Nuclear Medicine

    2012-07-01

    A novel zoledronic acid (ZL) derivative, 1-hydroxy-2-(2,4-dimethyl-1H-imidazol-1-yl)-ethane-1,1-diyldiphosphonic acid (DMIDP, dimezoledronate), was successfully prepared and labeled with {sup 99m}Tc in a high labeling yield. The biodistribution in mice shows that {sup 99m}Tc-DMIDP has significant advantage regarding bone resorption and clearance from soft tissues compared with {sup 99m}Tc-ZL and the clinically widely-used bone-imaging agent {sup 99m}Tc-MDP (methylenediphosphonic acid). Kinetics of blood clearance displayed that distribution half-life (T{sub 1/2{alpha}}) and elimination half-life (T{sub 1/2{beta}}) of {sup 99m}Tc-DMIDP were 2.53 min and 23.53 min, while those of {sup 99m}Tc-ZL were 2.28 and 52.63 min, respectively. Excellent images of the rabbit skeleton can be quickly obtained from {sup 99m}Tc-DMIDP, which was faster than {sup 99m}Tc-ZL and {sup 99m}Tc-MDP. The present findings indicate that {sup 99m}Tc-DMIDP possesses excellent potential for application as a novel bone scanning agent. (orig.)

  18. Biphasic calcium phosphates (BCP of hydroxyapatite (HA and tricalcium phosphate (TCP as bone substitutes: Importance of physicochemical characterizations in biomaterials studies

    Directory of Open Access Journals (Sweden)

    Mehdi Ebrahimi

    2017-02-01

    Full Text Available The data presented in this article are related to the research article entitled “Biphasic calcium phosphates bioceramics (HA/TCP: Concept, physicochemical properties and the impact of standardization of study protocols in biomaterials research” [1]. This article provides in depth study of BCP bone substitutes as valuable option in the field of tissue engineering. However, there are discrepancies in the literature regarding the ideal physicochemical properties of BCP and the ideal balance between different phase compositions for enhanced bone tissue engineering (M. Ebrahimi, M.G. Botelho, S.V. Dorozhkin, 2016; M. Ebrahimi, P. Pripatnanont, S. Suttapreyasri, N. Monmaturapoj, 2014 [1,2]. This is found to be mainly because of improper characterization of BCP bioceramics in basic studies and lack of standard study protocols in in vitro and in vivo research. This data article along with original article provide the basic data required for ideal characterization of BCP and other bioceramics in an attempt to provide basic standardized protocols for future studies.

  19. Nonmagnetic driver for piezoelectric actuators

    DEFF Research Database (Denmark)

    Ekhtiari, Marzieh

    2014-01-01

    Piezoelectric actuator drive aims to enable reliable motor performance in strong magnetic fields for magnetic res- onance imaging and computed tomography treatment tables. There are technical limitations in operation of these motors and drive systems related to magnetic interference. Piezoelectric...... actuators. Therefore, piezoelectric transformer-based power converters are used for driving piezoelectric actuator drive motor in the presence of high electromagnetic field....

  20. Piezoelectric cantilever sensors

    Science.gov (United States)

    Shih, Wan Y. (Inventor); Shih, Wei-Heng (Inventor); Shen, Zuyan (Inventor)

    2008-01-01

    A piezoelectric cantilever with a non-piezoelectric, or piezoelectric tip useful as mass and viscosity sensors. The change in the cantilever mass can be accurately quantified by monitoring a resonance frequency shift of the cantilever. For bio-detection, antibodies or other specific receptors of target antigens may be immobilized on the cantilever surface, preferably on the non-piezoelectric tip. For chemical detection, high surface-area selective absorbent materials are coated on the cantilever tip. Binding of the target antigens or analytes to the cantilever surface increases the cantilever mass. Detection of target antigens or analytes is achieved by monitoring the cantilever's resonance frequency and determining the resonance frequency shift that is due to the mass of the adsorbed target antigens on the cantilever surface. The use of a piezoelectric unimorph cantilever allows both electrical actuation and electrical sensing. Incorporating a non-piezoelectric tip (14) enhances the sensitivity of the sensor. In addition, the piezoelectric cantilever can withstand damping in highly viscous liquids and can be used as a viscosity sensor in wide viscosity range.

  1. Composites organiques-inorganiques pour la substitution et la réparation osseuse : concepts, premiers résultats et potentialités Organic-inorganic composites for bone substitute and bone repair applications: concepts, first results and potentialities

    Directory of Open Access Journals (Sweden)

    Peroglio Marianna

    2013-11-01

    Full Text Available Ce document présente un très bref aperçu de l'intérêt des matériaux composites organique – inorganique pour la substitution et la réparation osseuse. Deux types de composites sont présentés. Dans une première partie, des matériaux poreux en céramique ou bio-verre élaborés par la technologie des poudres sont imprégnés par un polymère. Cette imprégnation se traduit par une forte augmentation de l'énergie à la rupture du squelette céramique, permettant de limiter le risque de rupture fragile. L'augmentation des propriétés mécaniques des substituts osseux céramiques par une phase polymère peut être mise en regard des mécanismes de renforcement présents dans l'os et du rôle du collagène sur la ténacité de celui-ci. Dans une deuxième partie, des composites denses sont élaborés par des technologies de plasturgie, qui permettent de réaliser des produits de formes complexes. Les phases polymères et céramiques sont ici choisies pour leurs caractères respectifs résorbable et ostéo-inducteur. Ces composites permettent la création rapide d'hydroxyapatite à leur surface et accélèrent la guérison osseuse. A terme, ils sont résorbés. Ces deux exemples démontrent les potentialités de tels multi-matériaux architecturés pour la réalisation de substituts osseux plus résistants mécaniquement et apportant de nouvelles fonctionnalités, ainsi que pour la production de produits d'ostéosynthèse favorisant les processus de guérison osseuse. Here we show a brief outline of organic-inorganic composites for bone substitute and bone repair applications. Two types of composites are presented. In a first strategy, porous ceramics and bioactive glasses processed by sintering methods are impregnated by a polymer. The strong improvement of the mechanical properties of the ceramic scaffolds by a polymer phase can be linked to the one present in bone with the role of collagen on bone toughness. In a second strategy, a

  2. Notes on Piezoelectricity

    Energy Technology Data Exchange (ETDEWEB)

    Redondo, Antonio [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)

    2016-02-03

    These notes provide a pedagogical discussion of the physics of piezoelectricity. The exposition starts with a brief analysis of the classical (continuum) theory of piezoelectric phenomena in solids. The main subject of the notes is, however, a quantum mechanical analysis. We first derive the Frohlich Hamiltonian as part of the description of the electron-phonon interaction. The results of this analysis are then employed to derive the equations of piezoelectricity. A couple of examples with the zinc blende and and wurtzite structures are presented at the end

  3. Piezoelectric transducer array microspeaker

    KAUST Repository

    Carreno, Armando Arpys Arevalo

    2016-12-19

    In this paper we present the fabrication and characterization of a piezoelectric micro-speaker. The speaker is an array of micro-machined piezoelectric membranes, fabricated on silicon wafer using advanced micro-machining techniques. Each array contains 2n piezoelectric transducer membranes, where “n” is the bit number. Every element of the array has a circular shape structure. The membrane is made out four layers: 300nm of platinum for the bottom electrode, 250nm or lead zirconate titanate (PZT), a top electrode of 300nm and a structural layer of 50

  4. Bone healing around nanocrystalline hydroxyapatite, deproteinized bovine bone mineral, biphasic calcium phosphate, and autogenous bone in mandibular bone defects

    DEFF Research Database (Denmark)

    Broggini, Nina; Bosshardt, Dieter D; Jensen, Simon S

    2015-01-01

    The individual healing profile of a given bone substitute with respect to osteogenic potential and substitution rate must be considered when selecting adjunctive grafting materials for bone regeneration procedures. In this study, standardized mandibular defects in minipigs were filled with nanocr......The individual healing profile of a given bone substitute with respect to osteogenic potential and substitution rate must be considered when selecting adjunctive grafting materials for bone regeneration procedures. In this study, standardized mandibular defects in minipigs were filled...

  5. Piezoelectric MEMS resonators

    CERN Document Server

    Piazza, Gianluca

    2017-01-01

    This book introduces piezoelectric microelectromechanical (pMEMS) resonators to a broad audience by reviewing design techniques including use of finite element modeling, testing and qualification of resonators, and fabrication and large scale manufacturing techniques to help inspire future research and entrepreneurial activities in pMEMS. The authors discuss the most exciting developments in the area of materials and devices for the making of piezoelectric MEMS resonators, and offer direct examples of the technical challenges that need to be overcome in order to commercialize these types of devices. Some of the topics covered include: Widely-used piezoelectric materials, as well as materials in which there is emerging interest Principle of operation and design approaches for the making of flexural, contour-mode, thickness-mode, and shear-mode piezoelectric resonators, and examples of practical implementation of these devices Large scale manufacturing approaches, with a focus on the practical aspects associate...

  6. Energy collection via Piezoelectricity

    Science.gov (United States)

    Naveen Kumar, Ch

    2015-12-01

    In the present days, wireless data transmission techniques are commonly used in electronic devices. For powering them connection needs to be made to the power supply through wires else power may be supplied from batteries. Batteries require charging, replacement and other maintenance efforts. So, some alternative methods need to be developed to keep the batteries full time charged and to avoid the need of any consumable external energy source to charge the batteries. Mechanical energy harvesting utilizes piezoelectric components where deformations produced by different means are directly converted to electrical charge via piezoelectric effect. The proposed work in this research recommends Piezoelectricity as a alternate energy source. The motive is to obtain a pollution-free energy source and to utilize and optimize the energy being wasted. Current work also illustrates the working principle of piezoelectric crystal and various sources of vibration for the crystal.

  7. Bone marrow histopathology in the diagnostic evaluation of splenic marginal-zone and splenic diffuse red pulp small B-cell lymphoma: a reliable substitute for spleen histopathology?

    Science.gov (United States)

    Ponzoni, Maurilio; Kanellis, George; Pouliou, Evi; Baliakas, Panagiotis; Scarfò, Lydia; Ferreri, Andrés J M; Doglioni, Claudio; Bikos, Vasilis; Dagklis, Antonis; Anagnostopoulos, Achilles; Ghia, Paolo; Stamatopoulos, Kostas; Papadaki, Theodora

    2012-11-01

    Primary splenic small B-cell lymphomas mostly comprise the distinct entity of splenic marginal-zone lymphoma (SMZL) and the provisional category of splenic lymphoma/leukemia unclassifiable, mainly represented by the hairy cell leukemia variant and splenic diffuse red pulp small B-cell lymphoma (SDRL). Until recently, histopathologic examination of splenectomy specimens was considered mandatory for the diagnosis of SMZL. However, nowadays, mainly because of advances in chemoimmunotherapy, splenectomy is performed much less frequently. We evaluated the diagnostic efficacy of bone marrow biopsy (BMB) histopathology in the diagnostic approach toward SMZL and SDRL and tested whether it may serve as a substitute for spleen histopathology in the differential diagnosis between these 2 entities. To this end, we conducted a paired assessment of BMB and spleen diagnostic samples from 46 cases with a diagnosis of SMZL (n=32) or SDRL (n=14) based on spleen histopathology. We demonstrate that detailed immunohistopathologic BMB evaluation offers adequate evidence for the confirmation of these entities and their differential diagnosis from other small B-cell lymphoma histotypes. Notably, the immunophenotypical profile of SMZL and SDRL was identical in both BMB and spleen specimens for 21 evaluated markers. Paired assessment of BMB and spleen specimens did not identify discriminating patterns of BMB infiltration, cytology, and/or immunohistology between SMZL and SDRL. Accordingly, bone marrow histopathology contributes significantly in confirming the diagnosis of SMZL and SDRL. However, presently it is not possible to distinguish SMZL from SDRL on the basis of BMB evaluation alone; hence, histopathologic examination of the spleen remains the "gold standard" approach.

  8. Comparison and preparation of multilayered polylactic acid fabric strengthen calcium phosphate-based bone substitutes for orthopedic applications.

    Science.gov (United States)

    Chen, Wen-Cheng; Ko, Chia-Ling; Yang, Jia-Kai; Wu, Hui-Yu; Lin, Jia-Horng

    2016-03-01

    An attempt to maintain the three-dimensional space into restorative sites through the conveniently pack porous fillers are general used strategy. Advancement in the manufacturing protective shells in the scaffolds, which would be filled with brittle ceramic grafts for the development of highly connective pores provides the approach to solve crack problem for generating the tissues. Therefore, multilayered braided and alkalized poly(lactic acid) (PLA) composites with calcium phosphate bone cement (CPC) were synthesized and compared. The PLA/CPC composites were divided into various groups according to a series of heat-treatment temperatures (100-190 °C) and periods (1-3 h) and then characterized. The effects of 24-h immersion on the strength decay resistance of the samples were compared. Results showed that the residual oil capped on the surfaces of alkalized PLA braid was removed, and the structure was unaltered. However, the reduced tensile stress of alkalized PLA braids was due to ester-group formation by hydrolysis. Mechanical test results of PLA/CPC composites showed that the strength significantly increased after heat treatment, except when the heating temperature was higher than the PLA melting point at approximately 160-170 °C. The degree of PLA after recrystallization became higher than that of unheated composites, thereby leading to reduced strength and toughness of the specimen. Braiding fibers of biodegradable PLA reinforced and toughened the structure particularly of the extra-brittle material of thin-sheet CPC after implantation.

  9. Piezoelectric Energy Harvesting Solutions

    Directory of Open Access Journals (Sweden)

    Renato Caliò

    2014-03-01

    Full Text Available This paper reviews the state of the art in piezoelectric energy harvesting. It presents the basics of piezoelectricity and discusses materials choice. The work places emphasis on material operating modes and device configurations, from resonant to non-resonant devices and also to rotational solutions. The reviewed literature is compared based on power density and bandwidth. Lastly, the question of power conversion is addressed by reviewing various circuit solutions.

  10. Piezoelectrically Enhanced Photocathodes

    Science.gov (United States)

    Beach, Robert A.; Nikzad, Shouleh; Bell, Lloyd Douglas; Strittmatter, Robert

    2011-01-01

    Doping of photocathodes with materials that have large piezoelectric coefficients has been proposed as an alternative means of increasing the desired photoemission of electrons. Treating cathode materials to increase emission of electrons is called "activation" in the art. It has been common practice to activate photocathodes by depositing thin layers of suitable metals (usually, cesium). Because cesium is unstable in air, fabrication of cesiated photocathodes and devices that contain them must be performed in sealed tubes under vacuum. It is difficult and costly to perform fabrication processes in enclosed, evacuated spaces. The proposed piezoelectrically enhanced photocathodes would have electron-emission properties similar to those of cesiated photocathodes but would be stable in air, and therefore could be fabricated more easily and at lower cost. Candidate photocathodes include nitrides of elements in column III of the periodic table . especially compounds of the general formula Al(x)Ga(1.x)N (where 0< or = x < or =.1). These compounds have high piezoelectric coefficients and are suitable for obtaining response to ultraviolet light. Fabrication of a photocathode according to the proposal would include inducement of strain in cathode layers during growth of the layers on a substrate. The strain would be induced by exploiting structural mismatches among the various constituent materials of the cathode. Because of the piezoelectric effect in this material, the strain would give rise to strong electric fields that, in turn, would give rise to a high concentration of charge near the surface. Examples of devices in which piezoelectrically enhanced photocathodes could be used include microchannel plates, electron- bombarded charge-coupled devices, image tubes, and night-vision goggles. Piezoelectrically enhanced photocathode materials could also be used in making highly efficient monolithic photodetectors. Highly efficient and stable piezoelectrically enhanced

  11. Feasibility of Piezoelectric Endoscopic Transsphenoidal Craniotomy: A Cadaveric Study

    Directory of Open Access Journals (Sweden)

    Peter Valentin Tomazic

    2014-01-01

    Full Text Available Objective. Endoscopic transsphenoidal approach has become the gold standard for surgical treatment of treating pituitary adenomas or other lesions in that area. Opening of bony skull base has been performed with burrs, chisels, and hammers or standard instruments like punches and circular top knives. The creation of primary bone flaps—as in external craniotomies—is difficult.The piezoelectric osteotomes used in the present study allows creating a bone flap for endoscopic transnasal approaches in certain areas. The aim of this study was to prove the feasibility of piezoelectric endoscopic transnasal craniotomies. Study Design. Cadaveric study. Methods. On cadaveric specimens (N=5, a piezoelectric system with specially designed hardware for endonasal application was applied and endoscopic transsphenoidal craniotomies at the sellar floor, tuberculum sellae, and planum sphenoidale were performed up to a size of 3–5 cm2. Results. Bone flaps could be created without fracturing with the piezoosteotome and could be reimplanted. Endoscopic handling was unproblematic and time required was not exceeding standard procedures. Conclusion. In a cadaveric model, the piezoelectric endoscopic transsphenoidal craniotomy (PETC is technically feasible. This technique allows the surgeon to create a bone flap in endoscopic transnasal approaches similar to existing standard transcranial craniotomies. Future trials will focus on skull base reconstruction using this bone flap.

  12. Stretchable piezoelectric nanocomposite generator

    Science.gov (United States)

    Park, Kwi-Il; Jeong, Chang Kyu; Kim, Na Kyung; Lee, Keon Jae

    2016-06-01

    Piezoelectric energy conversion that generate electric energy from ambient mechanical and vibrational movements is promising energy harvesting technology because it can use more accessible energy resources than other renewable natural energy. In particular, flexible and stretchable piezoelectric energy harvesters which can harvest the tiny biomechanical motions inside human body into electricity properly facilitate not only the self-powered energy system for flexible and wearable electronics but also sensitive piezoelectric sensors for motion detectors and in vivo diagnosis kits. Since the piezoelectric ZnO nanowires (NWs)-based energy harvesters (nanogenerators) were proposed in 2006, many researchers have attempted the nanogenerator by using the various fabrication process such as nanowire growth, electrospinning, and transfer techniques with piezoelectric materials including polyvinylidene fluoride (PVDF) polymer and perovskite ceramics. In 2012, the composite-based nanogenerators were developed using simple, low-cost, and scalable methods to overcome the significant issues with previously-reported energy harvester, such as insufficient output performance and size limitation. This review paper provides a brief overview of flexible and stretchable piezoelectric nanocomposite generator for realizing the self-powered energy system with development history, power performance, and applications.

  13. Energy Harvesting via Piezoelectricity

    Directory of Open Access Journals (Sweden)

    Tanvi Dikshit

    2010-01-01

    Full Text Available In the present era, wireless data transmission techniques are commonly used in electronic devices. For powering them connection needs to be made to the power supply through wires else power may be supplied from batteries. Batteries require charging, replacement and other maintenance efforts. For example, in the applications such as villages, border areas, forests, hilly areas, where generally remote controlled devices are used, continuous charging of the microcells is not possible by conventional charging methods .So, some alternative methods needs to be developed to keep the batteries full time charged and to avoid the need of any consumable external energy source to charge the batteries.. To resolve such problems, Energy harvesting technique is proposed as the best alternative. There exists variety of energy harvesting techniques but mechanical energy harvesting happens to be the most prominent. This technique utilizes piezoelectric components where deformations produced by different means are directly converted to electrical charge via piezoelectric effect. Subsequently the electrical energy can be regulated or stored for further use. The proposed work in this research recommends Piezoelectricity as a alternate energy source. The motive is to obtain a pollution-free energy source and to utilize and optimize the energy being wasted. In this paper two important techniques are stressed upon to harness the energy viz Piezoelectric Windmill and Increased Bandwidth Piezoelectric Crystal. Current work also illustrates the working principle of piezoelectric crystal and various sources of vibration for the crystal.

  14. Effects of Mn substitution on ferro- and piezoelectric properties of Bi{sub 0.86}Sm{sub 0.14}FeO{sub 3} thin films

    Energy Technology Data Exchange (ETDEWEB)

    Yin Zaimei; Liu Jingjing [School of Materials Science and Engineering, University of Jinan (China); Hu Guangda, E-mail: gdhu@ujn.edu.cn [School of Materials Science and Engineering, University of Jinan (China); Wu Weibing; Yang Changhong [School of Materials Science and Engineering, University of Jinan (China)

    2011-03-03

    Research highlights: > 1 at.% Mn doping is necessary for obtaining the intrinsic properties of BSFO films. > Formation of Mn{sup 2+} is more likely based on the electronic configuration of Mn. > The negative effect of high Mn doping content on piezoresponse is more evident. - Abstract: The Bi{sub 0.86}Sm{sub 0.14}FeO{sub 3} (BSFO) and Bi{sub 0.86}Sm{sub 0.14}Fe{sub 1-x}Mn{sub x}O{sub 3} (BSFMO) (x = 0.01, 0.03, 0.05) thin films were deposited on indium tin oxide/glass substrates via a metal organic deposition method. 1 at.% Mn doping leads to an evident reduction of the leakage current in BSFO film. More importantly, the Bi{sub 0.86}Sm{sub 0.14}Fe{sub 0.99}Mn{sub 0.01}O{sub 3} film exhibits the lowest coercive field (E{sub c} = 272 kV/cm), the largest remanent polarization (P{sub r} = 53.6 {mu}c/cm{sup 2}) and the remanent out-of-plane piezoelectric coefficient (d{sub 33} = 146 pm/V). However, further increase of Mn doping content results in the deterioration of the charge retaining capability and the piezoelectric properties of the films. The negative influence of high Mn doping contents was discussed based on the structure change and the contribution of irreversible movement of non-180{sup o} domain walls in the aged films.

  15. Effect of crystallographic orientation in textured Ba0.92Ca0.08TiO3 piezoelectric ceramics

    Science.gov (United States)

    Haugen, Astri Bjørnetun; Morozov, Maxim I.; Johnsson, Mats; Grande, Tor; Einarsrud, Mari-Ann

    2014-10-01

    Strongly textured lead-free Ba0.92Ca0.08TiO3 piezoelectric ceramics were fabricated by tape casting and templated grain growth. Dense ceramics with both favorable ⟨100⟩ and unfavorable ⟨111⟩ texture were successfully prepared. Enhanced piezoelectric performance was demonstrated for ceramics with ⟨100⟩ texture, in line with the predictions based on reported piezoelectric coefficients of tetragonal BaTiO3. Due to the expanded tetragonal range through Ca-substitution, ⟨100⟩ texture is favorable over a wide temperature range. The ⟨100⟩ texture also results in the enhanced piezoelectric performance being temperature-independent. In addition to engineering of stable, high-performance lead-free piezoelectric ceramics, this study has demonstrated that consideration of the extender/rotator nature of piezoelectric properties is imperative for improving the piezoelectric response through texturing.

  16. High Temperature Piezoelectric Drill

    Science.gov (United States)

    Bao, Xiaoqi; Scott, James; Boudreau, Kate; Bar-Cohen, Yoseph; Sherrit, Stewart; Badescu, Mircea; Shrout, Tom; Zhang, Shujun

    2009-01-01

    The current NASA Decadal mission planning effort has identified Venus as a significant scientific target for a surface in-situ sampling/analyzing mission. The Venus environment represents several extremes including high temperature (460 deg C), high pressure (9 MPa), and potentially corrosive (condensed sulfuric acid droplets that adhere to surfaces during entry) environments. This technology challenge requires new rock sampling tools for these extreme conditions. Piezoelectric materials can potentially operate over a wide temperature range. Single crystals, like LiNbO3, have a Curie temperature that is higher than 1000 deg C and the piezoelectric ceramics Bismuth Titanate higher than 600 deg C. A study of the feasibility of producing piezoelectric drills that can operate in the temperature range up to 500 deg C was conducted. The study includes the high temperature properties investigations of engineering materials and piezoelectric ceramics with different formulas and doping. The drilling performances of a prototype Ultrasonic/Sonic Drill/Corer (USDC) using high temperate piezoelectric ceramics and single crystal were tested at temperature up to 500 deg C. The detailed results of our study and a discussion of the future work on performance improvements are presented in this paper.

  17. Stability analysis of piezoelectric beams

    NARCIS (Netherlands)

    Voß, T.; Scherpen, J.M.A.

    2011-01-01

    Piezoelectric materials are used in many engineering application. When modeling piezoelectric materials the standard assumption is that the electromagnetic field which is used to actuate the piezoelectric material is quasi static. In this paper we show that although the assumption of a quasi static

  18. Piezoelectric wave motor

    Science.gov (United States)

    Yerganian, Simon Scott

    2001-07-17

    A piezoelectric motor having a stator in which piezoelectric elements are contained in slots formed in the stator transverse to the desired wave motion. When an electric field is imposed on the elements, deformation of the elements imposes a force perpendicular to the sides of the slot, deforming the stator. Appropriate frequency and phase shifting of the electric field will produce a wave in the stator and motion in a rotor. In a preferred aspect, the piezoelectric elements are configured so that deformation of the elements in direction of an imposed electric field, generally referred to as the d.sub.33 direction, is utilized to produce wave motion in the stator. In a further aspect, the elements are compressed into the slots so as to minimize tensile stresses on the elements in use.

  19. Lead-Free Piezoelectrics

    CERN Document Server

    Nahm, Sahn

    2012-01-01

    Ecological restrictions in many parts of the world are demanding the elimination of Pb from all consumer items. At this moment in the piezoelectric ceramics industry, there is no issue of more importance than the transition to lead-free materials. The goal of Lead-Free Piezoelectrics is to provide a comprehensive overview of the fundamentals and developments in the field of lead-free materials and products to leading researchers in the world. The text presents chapters on demonstrated applications of the lead-free materials, which will allow readers to conceptualize the present possibilities and will be useful for both students and professionals conducting research on ferroelectrics, piezoelectrics, smart materials, lead-free materials, and a variety of applications including sensors, actuators, ultrasonic transducers and energy harvesters.

  20. Facile green synthesis of silver doped fluor-hydroxyapatite/β-cyclodextrin nanocomposite in the dual acting fluorine-containing ionic liquid medium for bone substitute applications

    Energy Technology Data Exchange (ETDEWEB)

    Jegatheeswaran, S. [Advanced Green Chemistry Lab, Department of Industrial Chemistry, School of Chemical Sciences, Alagappa University, Karaikudi-3, Tamil Nadu (India); Selvam, S. [Laser and Sensor Application Laboratory, Pusan National University, Busan 609735 (Korea, Republic of); Sri Ramkumar, V. [Deptartment of Environmental Biotechnology, School of Environmental, Sciences, Bharathidasan University, Tiruchirappalli, Tamilnadu (India); Sundrarajan, M., E-mail: sundrarajan@yahoo.com [Advanced Green Chemistry Lab, Department of Industrial Chemistry, School of Chemical Sciences, Alagappa University, Karaikudi-3, Tamil Nadu (India)

    2016-05-15

    Highlights: • Fluorine based ionic liquid was highly influenced the morphological structure of nanocomposites. • These composites has been motivated controlled release of silver nanoparticles for uniform antibacterial activity. • These material has given excellent antibacterial biofilm activity and favourable cytotoxical behavior on the human osteosarcoma (MG-63) cells. • These material has been highly suitable for bone substitute appliactions. - Abstract: A novel green route has approached for the synthesis of silver doped fluor-hydroxyapatite/β-cyclodextrin composite by the assistance of fluorine-based ionic liquid. The selected [BMIM]BF{sub 4} ionic liquid for this work plays a dual role as fluoride source and templating agent. It helps to improve the crystalline structures and the shape of the composites. The crystallinity, surface morphology, topographical studies of the synthesized composite were validated. The XRD results of the composite show typical Ag reflection peaks at 38.1°, 44.2° and 63.4°. The ionic liquid assisted composite displayed the hexagonal shaped HA particles, which are surrounded by spherical nano-Ag particles and these particles are uniformly dispersed in the β-cyclodextrin matrix in both horizontal and cross sections from surface morphology observations. The Ionic liquid assisted silver doped fluor-hydroxyapatite/β-cyclodextrin composite exhibited very good antibacterial activities against Escherichia coli, Salmonella typhi, Klebsiella pneumonia and Serratia liquefaciens pathogens. The antibacterial proficiencies were established using Confocal Laser Scanning Microscopic developed biofilms images and bacterial growth curve analysis. The cytotoxicity results of the ionic liquid assisted composite analyzed by cell proliferation in vitro studies using human osteosarcoma cell line (MG-63) and this study has shown excellent biocompatibility.

  1. Piezoelectric allostery of protein

    Science.gov (United States)

    Ohnuki, Jun; Sato, Takato; Takano, Mitsunori

    2016-07-01

    Allostery is indispensable for a protein to work, where a locally applied stimulus is transmitted to a distant part of the molecule. While the allostery due to chemical stimuli such as ligand binding has long been studied, the growing interest in mechanobiology prompts the study of the mechanically stimulated allostery, the physical mechanism of which has not been established. By molecular dynamics simulation of a motor protein myosin, we found that a locally applied mechanical stimulus induces electrostatic potential change at distant regions, just like the piezoelectricity. This novel allosteric mechanism, "piezoelectric allostery", should be of particularly high value for mechanosensor/transducer proteins.

  2. Piezoelectric Accelerometers Development

    DEFF Research Database (Denmark)

    Liu, Bin; Bang, Lisbet Fogh

    1999-01-01

    The paper describes the development of piezoelectric accelerometers using Finite Element (FE) approach. Brüel & Kjær Accelerometer Type 8325 is chosen as an example to illustrate the advanced accelerometer development procedure. The deviation between simulated results and measured results of Type...... 8325 are below 6%. It is proved that the specifications of the accelerometer can be effectively predicted using the FE method, especially when modifications of the accelerometer are required. The development process of piezoelectric accelerometers in Brüel & Kjær is becoming more efficient...

  3. Piezoelectric accelerometeres development

    DEFF Research Database (Denmark)

    Liu, Bin

    1999-01-01

    The paper describes the development of piezoelectric accelerometers using Finite Element (FE) approach. Brüel & Kjær Accelerometer Type 8325 is chosen as an example to illustrate the advanced accelerometer development procedure. The deviation between simulated results and measured results of Type...... 8325 are below 6%. It is proved that the specifications of the accelerometer can be effectively predicted using the FE method, especially when modifications of the accelerometer are required. The development process of piezoelectric accelerometers in Brüel & Kjær is becoming more efficient....

  4. Piezoelectric Ceramics Characterization

    Science.gov (United States)

    2001-09-01

    alloys, electrostrictive materials, magnetostrictive materials, electrorheological fluids are some examples of currently available smart materials...piezoelectric coefficients but also increase the dielectric constant and loss. They are utilized as actuators in vibration and noise control, benders, optical...or strain and electric field (equations (2) and (3)). High d-coefficients are desirable in materials utilized as actuators , such as in motional and

  5. Piezoelectric actuator renaissance

    Science.gov (United States)

    Uchino, Kenji

    2015-03-01

    This paper resumes the content of the invited talk of the author, read at the occasion of the International Workshop on Relaxor Ferroelectrics, IWRF 14, held on October 12-16, 2014 in Stirin, Czech Republic. It reviews the recent advances in materials, designing concepts, and new applications of piezoelectric actuators, as well as the future perspectives of this area.

  6. Development of efficient electron beam irradiating condition of artificial bone substitutes with 7 to 3 ratio of hydroxyapatite, tricalcium phosphate and type I collagen to maximize bony regeneration

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Soung Min; Eo, Mi Young; Myoung, Hoon; Kang, Ji Young; Lee, Jong Ho [Seoul National Univ., Seoul (Korea, Republic of); Cho, Hye Jin [Korea Basic Science Institute, Daejeon (Korea, Republic of); Yea, Kwon Hae; Lee, Byungcheol [Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of)

    2011-07-01

    Bony defects in oral and maxillofacial region was a common problem -Auto graft -Allograft -Xenograft. Accenting bone is 'Gold standard' for bone defect repair and from the rib, iliac crest, jaw and tibia. Bone is 70% inorganic components -which provide firmness, and approx. and 30% organic substances.

  7. A mechatronic power boosting design for piezoelectric generators

    Science.gov (United States)

    Liu, Haili; Liang, Junrui; Ge, Cong

    2015-10-01

    It was shown that the piezoelectric power generation can be boosted by using the synchronized switch power conditioning circuits. This letter reports a self-powered and self-sensing mechatronic design in substitute of the auxiliary electronics towards a compact and universal synchronized switch solution. The design criteria are derived based on the conceptual waveforms and a two-degree-of-freedom analytical model. Experimental result shows that, compared to the standard bridge rectifier interface, the mechatronic design leads to an extra 111% increase of generated power from the prototyped piezoelectric generator under the same deflection magnitude excitation. The proposed design has introduced a valuable physical insight of electromechanical synergy towards the improvement of piezoelectric power generation.

  8. A mechatronic power boosting design for piezoelectric generators

    Energy Technology Data Exchange (ETDEWEB)

    Liu, Haili; Liang, Junrui, E-mail: liangjr@shanghaitech.edu.cn; Ge, Cong [School of Information Science and Technology, ShanghaiTech University, No. 8 Building, 319 Yueyang Road, Shanghai 200031 (China)

    2015-10-05

    It was shown that the piezoelectric power generation can be boosted by using the synchronized switch power conditioning circuits. This letter reports a self-powered and self-sensing mechatronic design in substitute of the auxiliary electronics towards a compact and universal synchronized switch solution. The design criteria are derived based on the conceptual waveforms and a two-degree-of-freedom analytical model. Experimental result shows that, compared to the standard bridge rectifier interface, the mechatronic design leads to an extra 111% increase of generated power from the prototyped piezoelectric generator under the same deflection magnitude excitation. The proposed design has introduced a valuable physical insight of electromechanical synergy towards the improvement of piezoelectric power generation.

  9. Piezoelectric Resonator with Two Layers

    Science.gov (United States)

    Stephanou, Philip J. (Inventor); Black, Justin P. (Inventor)

    2013-01-01

    A piezoelectric resonator device includes: a top electrode layer with a patterned structure, a top piezoelectric layer adjacent to the top layer, a middle metal layer adjacent to the top piezoelectric layer opposite the top layer, a bottom piezoelectric layer adjacent to the middle layer opposite the top piezoelectric layer, and a bottom electrode layer with a patterned structure and adjacent to the bottom piezoelectric layer opposite the middle layer. The top layer includes a first plurality of electrodes inter-digitated with a second plurality of electrodes. A first one of the electrodes in the top layer and a first one of the electrodes in the bottom layer are coupled to a first contact, and a second one of the electrodes in the top layer and a second one of the electrodes in the bottom layer are coupled to a second contact.

  10. Piezoelectric step-motion actuator

    Science.gov (United States)

    Mentesana; Charles P.

    2006-10-10

    A step-motion actuator using piezoelectric material to launch a flight mass which, in turn, actuates a drive pawl to progressively engage and drive a toothed wheel or rod to accomplish stepped motion. Thus, the piezoelectric material converts electrical energy into kinetic energy of the mass, and the drive pawl and toothed wheel or rod convert the kinetic energy of the mass into the desired rotary or linear stepped motion. A compression frame may be secured about the piezoelectric element and adapted to pre-compress the piezoelectric material so as to reduce tensile loads thereon. A return spring may be used to return the mass to its resting position against the compression frame or piezoelectric material following launch. Alternative embodiment are possible, including an alternative first embodiment wherein two masses are launched in substantially different directions, and an alternative second embodiment wherein the mass is eliminated in favor of the piezoelectric material launching itself.

  11. High-fidelity piezoelectric loudspeaker

    OpenAIRE

    Fernández Martínez, Javier

    2014-01-01

    This project reports on a literature review about piezoelectric loudspeakers and on an experimental research about how to improve some features of a particular horned piezoelectric tweeter. The work involves an investigation of the performance and principle of operation of piezoelectric loudspeakers to understand how the sound is generated and what its main parameters are. Also, previous research papers about how to improve this type of speakers are reported. The knowledge gained was us...

  12. High Temperature Piezoelectric Drill

    Science.gov (United States)

    Bao, Xiaoqi; Bar-Cohen, Yoseph; Sherrit, Stewart; Badescu, Mircea; Shrout, Tom

    2012-01-01

    Venus is one of the planets in the solar systems that are considered for potential future exploration missions. It has extreme environment where the average temperature is 460 deg C and its ambient pressure is about 90 atm. Since the existing actuation technology cannot maintain functionality under the harsh conditions of Venus, it is a challenge to perform sampling and other tasks that require the use of moving parts. Specifically, the currently available electromagnetic actuators are limited in their ability to produce sufficiently high stroke, torque, or force. In contrast, advances in developing electro-mechanical materials (such as piezoelectric and electrostrictive) have enabled potential actuation capabilities that can be used to support such missions. Taking advantage of these materials, we developed a piezoelectric actuated drill that operates at the temperature range up to 500 deg C and the mechanism is based on the Ultrasonic/Sonic Drill/Corer (USDC) configuration. The detailed results of our study are presented in this paper

  13. ANALYSIS OF BEAMS WITH PIEZOELECTRIC ACTUATORS

    Institute of Scientific and Technical Information of China (English)

    林启荣; 刘正兴; 王宗利

    2001-01-01

    Based on the two-dimensional constitutive relationships of the piezoelectric material, an analytical solution for an intelligent beam excited by a pair of piezoelectric actuators is derived. With the solution the force and moment generated by two piezoelectric actuators and a pair of piezoelectric actuator/sensor are obtained. Examples of a cantilever piezoelectric laminated beam or a simply supported piezoelectric laminated beam, applied with voltages, are given.

  14. Black Branes as Piezoelectrics

    CERN Document Server

    Armas, Jay; Obers, Niels A

    2012-01-01

    We find a realization of linear electroelasticity theory in gravitational physics by uncovering a new response coefficient of charged black branes, exhibiting their piezoelectric behavior. Taking charged dilatonic black strings as an example and using the blackfold approach we measure their elastic and piezolectric moduli. We also use our results to draw predictions about the equilibrium condition of charged dilatonic black rings in dimensions higher than six.

  15. Black branes as piezoelectrics.

    Science.gov (United States)

    Armas, Jay; Gath, Jakob; Obers, Niels A

    2012-12-14

    We find a realization of linear electroelasticity theory in gravitational physics by uncovering a new response coefficient of charged black branes, exhibiting their piezoelectric behavior. Taking charged dilatonic black strings as an example and using the blackfold approach we measure their elastic and piezolectric moduli. We also use our results to draw predictions about the equilibrium condition of charged dilatonic black rings in dimensions higher than six.

  16. Piezoelectric wind turbine

    Science.gov (United States)

    Kishore, Ravi Anant; Priya, Shashank

    2013-03-01

    In past few years, there has been significant focus towards developing small scale renewable energy based power sources for powering wireless sensor nodes in remote locations such as highways and bridges to conduct continuous health monitoring. These prior efforts have led to the development of micro-scale solar modules, hydrogen fuel cells and various vibration based energy harvesters. However, the cost effectiveness, reliability, and practicality of these solutions remain a concern. Harvesting the wind energy using micro-to-small scale wind turbines can be an excellent solution in variety of outdoor scenarios provided they can operate at few miles per hour of wind speed. The conventional electromagnetic generator used in the wind mills always has some cogging torque which restricts their operation above certain cut-in wind speed. This study aims to develop a novel piezoelectric wind turbine that utilizes bimorph actuators for electro-mechanical energy conversion. This device utilizes a Savonius rotor that is connected to a disk having magnets at the periphery. The piezoelectric actuators arranged circumferentially around the disk also have magnets at the tip which interacts with the magnetic field of the rotating disk and produces cyclical deflection. The wind tunnel experiments were conducted between 2-12 mph of wind speeds to characterize and optimize the power output of the wind turbine. Further, testing was conducted in the open environment to quantify the response to random wind gusts. An attempt was made towards integration of the piezoelectric wind turbine with the wireless sensor node.

  17. Hybrid piezoelectric energy harvesting transducer system

    Science.gov (United States)

    Xu, Tian-Bing (Inventor); Jiang, Xiaoning (Inventor); Su, Ji (Inventor); Rehrig, Paul W. (Inventor); Hackenberger, Wesley S. (Inventor)

    2008-01-01

    A hybrid piezoelectric energy harvesting transducer system includes: (a) first and second symmetric, pre-curved piezoelectric elements mounted separately on a frame so that their concave major surfaces are positioned opposite to each other; and (b) a linear piezoelectric element mounted separately on the frame and positioned between the pre-curved piezoelectric elements. The pre-curved piezoelectric elements and the linear piezoelectric element are spaced from one another and communicate with energy harvesting circuitry having contact points on the frame. The hybrid piezoelectric energy harvesting transducer system has a higher electromechanical energy conversion efficiency than any known piezoelectric transducer.

  18. Mesenchymal stem cells and platelet gel improve bone deposition within CAD-CAM custom-made ceramic HA scaffolds for condyle substitution.

    Science.gov (United States)

    Ciocca, L; Donati, D; Ragazzini, S; Dozza, B; Rossi, F; Fantini, M; Spadari, A; Romagnoli, N; Landi, E; Tampieri, A; Piattelli, A; Iezzi, G; Scotti, R

    2013-01-01

    This study evaluated the efficacy of a regenerative approach using mesenchymal stem cells (MSCs) and CAD-CAM customized pure and porous hydroxyapatite (HA) scaffolds to replace the temporomandibular joint (TMJ) condyle. Pure HA scaffolds with a 70% total porosity volume were prototyped using CAD-CAM technology to replace the two temporomandibular condyles (left and right) of the same animal. MSCs were derived from the aspirated iliac crest bone marrow, and platelets were obtained from the venous blood of the sheep. Custom-made surgical guides were created by direct metal laser sintering and were used to export the virtual planning of the bone cut lines into the surgical environment. Sheep were sacrificed 4 months postoperatively. The HA scaffolds were explanted, histological specimens were prepared, and histomorphometric analysis was performed. Analysis of the porosity reduction for apposition of newly formed bone showed a statistically significant difference in bone formation between condyles loaded with MSC and condyles without (P < 0.05). The bone ingrowth (BI) relative values of split-mouth comparison (right versus left side) showed a significant difference between condyles with and without MSCs (P < 0.05). Analysis of the test and control sides in the same animal using a split-mouth study design was performed; the condyle with MSCs showed greater bone formation. The split-mouth design confirmed an increment of bone regeneration into the HA scaffold of up to 797% upon application of MSCs.

  19. Mesenchymal Stem Cells and Platelet Gel Improve Bone Deposition within CAD-CAM Custom-Made Ceramic HA Scaffolds for Condyle Substitution

    Directory of Open Access Journals (Sweden)

    L. Ciocca

    2013-01-01

    Full Text Available Purpose. This study evaluated the efficacy of a regenerative approach using mesenchymal stem cells (MSCs and CAD-CAM customized pure and porous hydroxyapatite (HA scaffolds to replace the temporomandibular joint (TMJ condyle. Methods. Pure HA scaffolds with a 70% total porosity volume were prototyped using CAD-CAM technology to replace the two temporomandibular condyles (left and right of the same animal. MSCs were derived from the aspirated iliac crest bone marrow, and platelets were obtained from the venous blood of the sheep. Custom-made surgical guides were created by direct metal laser sintering and were used to export the virtual planning of the bone cut lines into the surgical environment. Sheep were sacrificed 4 months postoperatively. The HA scaffolds were explanted, histological specimens were prepared, and histomorphometric analysis was performed. Results. Analysis of the porosity reduction for apposition of newly formed bone showed a statistically significant difference in bone formation between condyles loaded with MSC and condyles without (P<0.05. The bone ingrowth (BI relative values of split-mouth comparison (right versus left side showed a significant difference between condyles with and without MSCs (P<0.05. Analysis of the test and control sides in the same animal using a split-mouth study design was performed; the condyle with MSCs showed greater bone formation. Conclusion. The split-mouth design confirmed an increment of bone regeneration into the HA scaffold of up to 797% upon application of MSCs.

  20. Piezoelectric Torsional Vibration Driven Motor

    Science.gov (United States)

    2000-10-29

    20 which can provide large amplitude rotational motion with a high torque. 21 Piezoelectric ultrasonic motors have been developed using traveling...Motor for High Torque", T. S. Glenn, W.G. Hagwood, SPIE Volume 3041, 4 1997. These piezoelectric ultrasonic motors are of limited application

  1. A Piezoelectric Shear Stress Sensor

    Science.gov (United States)

    Kim, Taeyang; Saini, Aditya; Kim, Jinwook; Gopalarathnam, Ashok; Zhu, Yong; Palmieri, Frank L.; Wohl, Christopher J.; Jiang, Xiaoning

    2016-01-01

    In this paper, a piezoelectric sensor with a floating element was developed for shear stress measurement. The piezoelectric sensor was designed to detect the pure shear stress suppressing effects of normal stress generated from the vortex lift-up by applying opposite poling vectors to the: piezoelectric elements. The sensor was first calibrated in the lab by applying shear forces and it showed high sensitivity to shear stress (=91.3 +/- 2.1 pC/Pa) due to the high piezoelectric coefficients of PMN-33%PT (d31=-1330 pC/N). The sensor also showed almost no sensitivity to normal stress (less than 1.2 pC/Pa) because of the electromechanical symmetry of the device. The usable frequency range of the sensor is 0-800 Hz. Keywords: Piezoelectric sensor, shear stress, floating element, electromechanical symmetry

  2. Piezoelectric Transformers: An Historical Review

    Directory of Open Access Journals (Sweden)

    Alfredo Vazquez Carazo

    2016-04-01

    Full Text Available Piezoelectric transformers (PTs are solid-state devices that transform electrical energy into electrical energy by means of a mechanical vibration. These devices are manufactured using piezoelectric materials that are driven at resonance. With appropriate design and circuitry, it is possible to step up and step down the voltages between the input and output sections of the piezoelectric transformer, without making use of magnetic materials and obtaining excellent conversion efficiencies. The initial concept of a piezoelectric ceramic transformer was proposed by Charles A. Rosen in 1954. Since then, the evolution of piezoelectric transformers through history has been linked to the relevant work of some excellent researchers as well as to the evolution in materials, manufacturing processes, and driving circuit techniques. This paper summarizes the historical evolution of the technology.

  3. High-Temperature Piezoelectric Sensing

    Directory of Open Access Journals (Sweden)

    Xiaoning Jiang

    2013-12-01

    Full Text Available Piezoelectric sensing is of increasing interest for high-temperature applications in aerospace, automotive, power plants and material processing due to its low cost, compact sensor size and simple signal conditioning, in comparison with other high-temperature sensing techniques. This paper presented an overview of high-temperature piezoelectric sensing techniques. Firstly, different types of high-temperature piezoelectric single crystals, electrode materials, and their pros and cons are discussed. Secondly, recent work on high-temperature piezoelectric sensors including accelerometer, surface acoustic wave sensor, ultrasound transducer, acoustic emission sensor, gas sensor, and pressure sensor for temperatures up to 1,250 °C were reviewed. Finally, discussions of existing challenges and future work for high-temperature piezoelectric sensing are presented.

  4. Piezoelectric extraction of ECG signal

    Science.gov (United States)

    Ahmad, Mahmoud Al

    2016-11-01

    The monitoring and early detection of abnormalities or variations in the cardiac cycle functionality are very critical practices and have significant impact on the prevention of heart diseases and their associated complications. Currently, in the field of biomedical engineering, there is a growing need for devices capable of measuring and monitoring a wide range of cardiac cycle parameters continuously, effectively and on a real-time basis using easily accessible and reusable probes. In this paper, the revolutionary generation and extraction of the corresponding ECG signal using a piezoelectric transducer as alternative for the ECG will be discussed. The piezoelectric transducer pick up the vibrations from the heart beats and convert them into electrical output signals. To this end, piezoelectric and signal processing techniques were employed to extract the ECG corresponding signal from the piezoelectric output voltage signal. The measured electrode based and the extracted piezoelectric based ECG traces are well corroborated. Their peaks amplitudes and locations are well aligned with each other.

  5. Effects of electron-beam irradiation to the hydroxyapatite and tricalcium phosphate mixtures for the development of new synthetic bone substitutes

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Soung Min; Eo, Mi Young; Kang, Ji Young; Park, Jung Min; Seo, Mi Hyun; Myoung, Hoon; Lee, Jong Ho [Seoul National Univ., Seoul (Korea, Republic of); Han, Young Hwan; Lee, Byung Cheol [Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of)

    2010-07-01

    The aim of this study is to evaluate the effect and potential of electron beam irradiation treatment to new bone formation and healing in rat calvarial bone defects using hydroxyapatite and tricalcium phosphate mixtures. We used 1.0-2.0 MeV linear accelerator and 2.0 MeV superconductive linear accelerator with different irradiation dose such as 1, 30, 60 kGy. Structural changes in this synthetic bone material were analyzed in vitro, such as SEM, elementary and FE-SEM, ATR-IR, and CSR. And after sterilization with ethylene oxide, we use it as a bone graft material, in vivo. Bilateral, standardized truenesses circular calvarial defects, 7.0 mm in diameter, were created in male Sprague-Dawley rats. In each experimental group, the defect was filled with electron beam irradiated synthetic bony mixtures. Rate were sacrificed 2, 4 and 8 weeks post-op. for radiographic, histomorphologic, immunohistochemical staining, TEM, and elementary analysis.

  6. Bio-Oss Bone Substitutes Combined with Bone Rubbish Autotransplantation in Implantation of Maxillary Sinus lift and Simultaneous Dental Implantation%Bio-Oss骨代用品混合自体骨碎屑移植在开窗法上颌窦底提升同期牙种植体植入术中的应用

    Institute of Scientific and Technical Information of China (English)

    韩尚哲; 刘玉柱; 胡青; 谢美艳; 张倩

    2016-01-01

    目的 探讨自体骨碎屑混合Bio-Oss骨代用品用于侧壁开窗上颌窦底提升术同期牙种植体植入的临床效果. 方法 选择2013年1月—2014年6月于解放军62医院口腔科就诊的牙列缺损患者28例,利用种植机于阻生下颌第3磨牙制备合适足量的骨碎屑,与Bio-Oss骨代用品混合植入提升上颌窦底,侧壁开窗区表面覆盖Bio-Gide可吸收胶原膜,种植体同期植入. 观察种植效果. 结果 本组28例共植入32枚种植体,均获得骨结合,种植体无松动脱落. 所有病例完成修复后随访6个月,修复效果满意. 结论 Bio-Oss骨代用品混合自体骨碎屑移植在开窗法上颌窦底提升同期牙种植体植入术中临床效果良好.%Objective To investigate the effect of bone rubbish autotransplantation combined with Bio-Oss bone substitutes in implantation of maxillary sinus lift and simultaneous dental implantation. Methods A total of 28 patients with dentition defect during January 2013 and June 2014 were recruited in this study. The ample numbers of bone rubbish were obtained using bone block of mandibular third molar region, and then were combined with Bio-Oss bone substitutes in implantation of maxillary sinus floor for lifting. Bio-Gide adsorbable collagenous membrane covered the surface of side windowing area with simultaneous implantation. The effect of implantation was observed. Results A total of 32 implants were obtained in the 28 patients, and synostosis was performed for all implants without loosening or shedding. All the pa-tients were followed up for 6 months with satisfactory effect. Conclusion The bio-oss bone substitutes combined with bone rubbish autotransplantation in implantation of maxillary sinus lift and simultaneous dental implantation can achieve good effect.

  7. Simple piezoelectric translation device

    Science.gov (United States)

    Niedermann, Ph.; Emch, R.; Descouts, P.

    1988-02-01

    We describe a piezoelectric device which allows continuous movement and high-resolution micropositioning, without distance limitation. Both mechanical construction and the electronics for the device are very simple. The movement is obtained via a stick-slip mechanism, and steps as small as 10 nm are obtained. A displacement speed of 0.4 mm/s has been attained, and the device was capable of carrying several times its own weight, exerting a horizontal force, or climbing a plane inclined by 7°. Due to its compact construction, the device shows prospects for miniaturization.

  8. Enhanced Piezoelectric Shunt Design

    Directory of Open Access Journals (Sweden)

    Chul H. Park

    2003-01-01

    Full Text Available Piezoceramic material connected to an electronic shunt branch circuit has formed a successful vibration reduction device. One drawback of the conventional electronic shunt circuit is the large inductance required when suppressing low frequency vibration modes. Also, the large internal resistance associated with this large inductance exceeds the optimal design resistance needed for low frequency vibration suppression. To solve this problem, a modified and enhanced piezoelectric shunt circuit is designed and analyzed by using mechanical-electrical analogies to present the physical interpretation. The enhanced shunt circuit developed in this paper is proved to significantly reduce the targeted vibration mode of a cantilever beam, theoretically and experimentally.

  9. Nanostructured piezoelectric energy harvesters

    CERN Document Server

    Briscoe, Joe

    2014-01-01

    This book covers a range of devices that use piezoelectricity to convert mechanical deformation into electrical energy and relates their output capabilities to a range of potential applications. Starting with a description of the fundamental principles and properties of piezo- and ferroelectric materials, where applications of bulk materials are well established, the book shows how nanostructures of these materials are being developed for energy harvesting applications. The authors show how a nanostructured device can be produced, and put in context some of the approaches that are being invest

  10. High Temperature, High Power Piezoelectric Composite Transducers

    OpenAIRE

    Hyeong Jae Lee; Shujun Zhang; Yoseph Bar-Cohen; Stewart Sherrit

    2014-01-01

    Piezoelectric composites are a class of functional materials consisting of piezoelectric active materials and non-piezoelectric passive polymers, mechanically attached together to form different connectivities. These composites have several advantages compared to conventional piezoelectric ceramics and polymers, including improved electromechanical properties, mechanical flexibility and the ability to tailor properties by using several different connectivity patterns. These advantages have le...

  11. Relaxor-PT Single Crystal Piezoelectric Sensors

    OpenAIRE

    Xiaoning Jiang; Jinwook Kim; Kyugrim Kim

    2014-01-01

    Relaxor-PbTiO3 piezoelectric single crystals have been widely used in a broad range of electromechanical devices, including piezoelectric sensors, actuators, and transducers. This paper reviews the unique properties of these single crystals for piezoelectric sensors. Design, fabrication and characterization of various relaxor-PT single crystal piezoelectric sensors and their applications are presented and compared with their piezoelectric ceramic counterparts. Newly applicable fields and futu...

  12. Calculations for Piezoelectric Ultrasonic Transducers

    DEFF Research Database (Denmark)

    Jensen, Henrik

    1986-01-01

    Analysis of piezoelectric ultrasonic transducers implies a solution of a boundary value problem, for a boay which consists of different materials, including a piezoelectric part. The problem is dynamic at frequencies, where a typical wavelength is somewhat less than the size of the body. Radiation...... and in particular the finite element method are considered. The finite element method is utilized for analysis of axisymmetric transducers. An explicit, fully piezoelectric, triangular ring element, with linear variations in displacememnt and electric potential is given. The influence of a fluid half-space is also...

  13. Study of calcium carbonate eggshell powder for potential use as bone substitute%碳磷灰石鸡蛋壳粉作为骨修复材料的初步研究

    Institute of Scientific and Technical Information of China (English)

    王淑敏; 张珂; 俞立英; 周鸿国; 丁亚通; 蔡意达

    2014-01-01

    Objective To develop a new bone substitute derived from avian eggshell (ES) using micro-wave processing and observe its abilities of bone formation. Methods Calcium carbonate ES powder was pre-pared by microwave method with different heating time. The physicochemical characteristics of the new materials with or without microwave heating were analyzed by SEM、EDXA、XRD、FT-IR . A pilot animal study was conducted by creating standard defects of 5 mm diameter on parietal bone of New Zealand rabbits. The defects were filled with 60 min microwave heated ES powder whereas using microwave untreated ES powder and Bio-Oss in comparison. After 8 weeks new bone formation of defects were observed. Results SEM, XRD, FT-IR and EDXA analysis showed the micromorphology of the new materials turned from needle-like to ball-like structures as the microwave heating time prolonged. The characteristic peak of calcium carbonate was also increased at the same time. Carbon, phosphorus and calcium were confirmed in the new material as well. Animal study showed 5 mm defects on parietal bone filled with calcium carbonate ES powder had more calcified bone formation and less uncalcified new bone. Conclusions The study demonstrated the efficient use of microwave in converting ES powder from natural CaCO3 into calcium carbonate. The new material might be a potential bone substitute.%目的:研制一种新型的碳磷灰石骨修复材料,初步观察其成骨作用。方法:以鸡蛋壳为原料,采用微波法制备不同加热条件下的骨修复材料,利用扫描电镜(SEM)、X射线衍射仪(XRD)、傅立叶红外(FT-IR)和能谱分析(EDXA)手段,表征微波处理前后材料的理化性能。进一步选用新西兰兔制备直径5mm的颅骨全层缺损区,以未经微波处理的鸡蛋壳粉及Bio-Oss作为对照,充填经微波处理后的新型骨修复材料,8周后观察新生骨的生成情况。结果:SEM, XRD, FT-IR和EDXA分析证实:

  14. Nuevos enfoques para mejorar las propiedades mecánicas y biológicas de substitutos óseos basados en calcio (New Approaches for Improving Mechanical and Biological Properties of Calcium-Based Bone Substitutes

    Directory of Open Access Journals (Sweden)

    Arias Fernández, José Ignacio.

    2007-12-01

    Full Text Available ResumenEl proceso biológico por el cual los seres vivos logran una mineralización inorgánica se conoce como biomineralización. Las investigaciones en implantes óseos han intentado aprovechar el proceso natural de regeneración del hueso, utilizando sustitutos óseos que posean características de osteo-inducción, integración y conducción similares al hueso propio. Entre los sustitutos óseos podemos mencionar el uso de estructuras calcáreas naturales como la de los corales (compuestos de carbonato de calcio que en algunos casos son fosfatados superficialmente, la generación de diversos cementos y cerámicas porosas en base a fosfato tricálcico a y b solos o mezclados con compuestos orgánicos naturales o sintéticos; como pueden ser entre otros colágeno, quitosano, hidrogeles, derivados del ácido poliglicólico o compuestos acrílicos para mejorar sus deficiencias de rapidez de disolución y mejorar las propiedades mecánicas. Una de las formas más ocupadas del fosfato de calcio es la hidroxiapatita (HA que también ha sido mezclada con diversos compuestos orgánicos e inorgánicos con el fin de mejorar su resistencia a fuerzas de tensión, compresión y flexión. Los desafíos futuros son por lo tanto lograr compuestos que no sólo permitan la regeneración ósea sino que además den soporte mecánico mientras este proceso ocurre. En la presente monografía se revisan las principales características químicas, físicas y biológicas de los compuestos cálcicos utilizados como sustitutos óseos, y se proponen nuevos enfoques que deberían considerarse para mejorar su eficiencia. SummaryThe biological process for which living organisms achieve an inorganic mineralization is known as biomineralization. Research in bone implants has tried to mimick the natural process of regeneration of bone by using bone substitutes possessing characteristics of osteo-induction, integration and conduction similar to that of natural bone. Among other

  15. Piezoelectric Rotary Tube Motor

    Science.gov (United States)

    Fisher, Charles D.; Badescu, Mircea; Braun, David F.; Culhane, Robert

    2011-01-01

    A custom rotary SQUIGGLE(Registered TradeMark) motor has been developed that sets new benchmarks for small motor size, high position resolution, and high torque without gear reduction. Its capabilities cannot be achieved with conventional electromagnetic motors. It consists of piezoelectric plates mounted on a square flexible tube. The plates are actuated via voltage waveforms 90 out of phase at the resonant frequency of the device to create rotary motion. The motors were incorporated into a two-axis postioner that was designed for fiber-fed spectroscopy for ground-based and space-based projects. The positioner enables large-scale celestial object surveys to take place in a practical amount of time.

  16. Cryogenic Rotary Piezoelectric Motor Project

    Data.gov (United States)

    National Aeronautics and Space Administration — Piezoelectric motors operate on the principal of high frequency oscillation of high force precision ceramic elements. The high power oscillations are converted to...

  17. NEW PRECISION PIEZOELECTRIC STEP ACTUATOR

    Institute of Scientific and Technical Information of China (English)

    LIU Jianfang; YANG Zhigang; FAN Zunqiang; CHENG Guangming

    2006-01-01

    A new precision piezoelectric actuator is proposed to improve its drive capabilities. The actuator is based on the piezoelectric technology. It adopts the principle of bionics and works with a new method of stator initiative anchoring/loosen and a distortion structure of double-side thin flexible hinge. It solves the problem of anchoring/loosen, frequency, journey, resolution and velocity. The experiment shows that the new linear piezoelectric actuator works with high frequency (100 Hz), high speed (502 μm/s), large travel (>10 mm), high resolution (0.05 μm) and high load (100 N). This kind of new piezoelectric actuator will be applied for large travel and high resolution driving device, optics engineering, precision positioning and some micromanipulation field.

  18. Piezoelectric enhancement under negative pressure

    Science.gov (United States)

    Kvasov, Alexander; McGilly, Leo J.; Wang, Jin; Shi, Zhiyong; Sandu, Cosmin S.; Sluka, Tomas; Tagantsev, Alexander K.; Setter, Nava

    2016-07-01

    Enhancement of ferroelectric properties, both spontaneous polarization and Curie temperature under negative pressure had been predicted in the past from first principles and recently confirmed experimentally. In contrast, piezoelectric properties are expected to increase by positive pressure, through polarization rotation. Here we investigate the piezoelectric response of the classical PbTiO3, Pb(Zr,Ti)O3 and BaTiO3 perovskite ferroelectrics under negative pressure from first principles and find significant enhancement. Piezoelectric response is then tested experimentally on free-standing PbTiO3 and Pb(Zr,Ti)O3 nanowires under self-sustained negative pressure, confirming the theoretical prediction. Numerical simulations verify that negative pressure in nanowires is the origin of the enhanced electromechanical properties. The results may be useful in the development of highly performing piezoelectrics, including lead-free ones.

  19. A piezoelectrically actuated ball valve

    Science.gov (United States)

    Erwin, L. R.; Schwartz, H. W.; Teitelbaum, B. R.

    1972-01-01

    Bimorph strip composed of two layers of poled piezoelectric ceramic material closes and opens valve. Strip performs like capacitator, allowing initial inrush of current when valve is energized and then only small leakage current flows as valve remains energized.

  20. Cryogenic Rotary Piezoelectric Motor Project

    Data.gov (United States)

    National Aeronautics and Space Administration — Piezoelectric motors operate on the principal of converting the high-frequency oscillation of high-force, precision ceramic elements into useful continuous motion....

  1. THRUST FORCE AND TORQUE IN DRILLING THE NATURAL FIBER REINFORCED POLYMER COMPOSITE MATERIALS AND EVALUATION OF DELAMINATION FACTOR FOR BONE GRAFT SUBSTITUTES -A WORK OF FICTION APPROACH

    Directory of Open Access Journals (Sweden)

    D. CHANDRAMOHAN

    2010-11-01

    Full Text Available This paper discusses about the Natural Fiber Reinforced Composite Materials contribution as bone implants. Biomaterial science is an interdisciplinary field that represents one of the most sophisticated trends in worldwide medical practice. In the last decades, researchers have developed new materials to improve the quality of human life. Owing to the frequent occurrence of bone fractures, it is important to develop a plate material for fixation on the fractured bone. These plate materials have to be lightweight, allow stiffness, and be biocompatible with humans. Drilling is the most frequently employed operation of secondary machining for fiber-reinforced materials, owing to the need for joining fractured bone by means of plate material in the field of orthopedics. An effort to utilize theadvantages offered by renewable resources for the development of biocomposite materials based on biopolymers and natural fibers has been made through fabrication of Natural fiber powdered material (Sisal (Agave sisalana, Banana (Musa sepientum, and Roselle (Hibiscus sabdariffa reinforced polymer composite plate material by using bio epoxy resin Grade 3554A and Hardner 3554B. Instead of orthopedics alloys such as Titanium, Cobalt chrome, Stainless steel, and Zirconium, this plate material can be used for internal fixationand aso external fixation on human body for fractured bone. The present work focuses on the prediction of thrust force and torque of the natural fiber reinforced polymer composite materials, and the values, compared with the Regression model and the Scheme of Delamination factor / zone using machine vision system, also discussed with the help of Scanning Electron Microscope [SEM].

  2. Substitutional analysis

    CERN Document Server

    Rutherford, Daniel Edwin

    2013-01-01

    Classic monograph, suitable for advanced undergraduates and graduate students. Topics include calculus of permutations and tableaux, semi-normal representation, orthogonal and natural representations, group characters, and substitutional equations. 1968 edition.

  3. Sugar Substitutes

    Science.gov (United States)

    ... drinks. You may also have heard them called "artificial sweeteners" or "non-caloric sweeteners." They can be used ... of nutrition for your body.What sugar substitutes/artificial sweeteners are approved by the FDA?The following sugar ...

  4. The study of bone repair effect of recombinant human bone morphogenetic protein-2 combined with artificial bone substitute materials in alveolar defect around the dental implant%骨形态发生蛋白2复合人工骨替代材料修复犬种植体周骨缺损的研究

    Institute of Scientific and Technical Information of China (English)

    张敬阳; 黄翠

    2014-01-01

    Objective To evaluate the bone repair capacity of β-tricalciumphosphate (β-TCP) or Bio-Oss combined with recombinant human bone morphogenetic protein-2 (rhBMP-2) in Beagle dogs.Methods Ten healthy adult Beagle dogs were used in this study.The mandibular premolars of the dogs were extracted firstly.Three months later,dental implants were placed in the mandibular,and a 5 mm× 4 mm× 3 mm bone defect area was prepared on the buccal side of each implant.The bone defect areas were filled with β-TCP,rhBMP-2/β-TCP compound,Bio-Oss or rhBMP-2/Bio-Oss compound respectively.The bone defect areas were filled nothing as the blank.The dogs were sacrificed after 4 or 12 weeks.Samples were prepared for the gross observation,X-ray analysis and histomorphology analysis.Results The new bone formation was observed in all experiment groups.After 4 weeks,the bone density of materials combined with rhBMP-2 groups [(36.70 ± 1.73) % and (38.50 ± 1.83) %] were higher than the raw materials groups [(30.50 ± 1.81)% and (31.48 ± 1.86)%].After 12 weeks,the bone density of materials combined with rhBMP-2 groups [(52.84 ± 1.85) % and (54.85 ± 1.87) %] were also higher than the raw materials groups [(43.65 ± 1.81) % and (44.94 ± 1.88) %].And new bone formation rate of the materials combined with rhBMP-2 groups were higher than the raw materials groups at each evaluation time.Conclusion rhBMP-2 can promote the bone regeneration activity of the artificial bone substitute materials effectively.%目的 观察重组人骨形态发生蛋白-2(rhBMP-2)复合β-磷酸三钙(β-TCP)及无机牛骨(Bio-Oss)对骨缺损修复能力的影响.方法 拔除10条Beagle犬下颌前磨牙,3个月骨质愈合后预备种植窝并制备5 mm×4 mm×3 mm骨缺损区,植入种植体,并分别在骨缺损区填入β-TCP、rhBMP-2/β-TCP复合物、Bio-Oss或rhBMP-2/Bio-Oss复合物;空白对照组不充填.术后4、12周处死犬,行大体观察、X线观察和组织形态

  5. Bismuth Sodium Titanate Based Materials for Piezoelectric Actuators.

    Science.gov (United States)

    Reichmann, Klaus; Feteira, Antonio; Li, Ming

    2015-12-04

    The ban of lead in many electronic products and the expectation that, sooner or later, this ban will include the currently exempt piezoelectric ceramics based on Lead-Zirconate-Titanate has motivated many research groups to look for lead-free substitutes. After a short overview on different classes of lead-free piezoelectric ceramics with large strain, this review will focus on Bismuth-Sodium-Titanate and its solid solutions. These compounds exhibit extraordinarily high strain, due to a field induced phase transition, which makes them attractive for actuator applications. The structural features of these materials and the origin of the field-induced strain will be revised. Technologies for texturing, which increases the useable strain, will be introduced. Finally, the features that are relevant for the application of these materials in a multilayer design will be summarized.

  6. Bismuth Sodium Titanate Based Materials for Piezoelectric Actuators

    Directory of Open Access Journals (Sweden)

    Klaus Reichmann

    2015-12-01

    Full Text Available The ban of lead in many electronic products and the expectation that, sooner or later, this ban will include the currently exempt piezoelectric ceramics based on Lead-Zirconate-Titanate has motivated many research groups to look for lead-free substitutes. After a short overview on different classes of lead-free piezoelectric ceramics with large strain, this review will focus on Bismuth-Sodium-Titanate and its solid solutions. These compounds exhibit extraordinarily high strain, due to a field induced phase transition, which makes them attractive for actuator applications. The structural features of these materials and the origin of the field-induced strain will be revised. Technologies for texturing, which increases the useable strain, will be introduced. Finally, the features that are relevant for the application of these materials in a multilayer design will be summarized.

  7. Piezoelectric Nanowires in Energy Harvesting Applications

    Directory of Open Access Journals (Sweden)

    Zhao Wang

    2015-01-01

    Full Text Available Recently, the nanogenerators which can convert the mechanical energy into electricity by using piezoelectric one-dimensional nanomaterials have exhibited great potential in microscale power supply and sensor systems. In this paper, we provided a comprehensive review of the research progress in the last eight years concerning the piezoelectric nanogenerators with different structures. The fundamental piezoelectric theory and typical piezoelectric materials are firstly reviewed. After that, the working mechanism, modeling, and structure design of piezoelectric nanogenerators were discussed. Then the recent progress of nanogenerators was reviewed in the structure point of views. Finally, we also discussed the potential application and future development of the piezoelectric nanogenerators.

  8. Characterization of silane coated hollow sphere alumina-reinforced ultra high molecular weight polyethylene composite as a possible bone substitute material

    Indian Academy of Sciences (India)

    S Roy; S Pal

    2002-12-01

    Silane coated hollow sphere alumina ceramic particles were moulded with ultra high molecular weight polyethylene (UHMWPE) to form a series of composites with alumina weight percent in the range from 15 to 50. The composites were prepared in a cylindrical mould using powder-processing technique. The composites were characterized for mechanical properties using destructive and non-destructive ultrasonic testing methods. The physical properties of the composite were determined and compared with those of cortical bone.

  9. Reduction in fluoride-induced genotoxicity in mouse bone marrow cells after substituting high fluoride-containing water with safe drinking water.

    Science.gov (United States)

    Podder, Santosh; Chattopadhyay, Ansuman; Bhattacharya, Shelley

    2011-10-01

    Treatment of mice with 15 mg l(-1) sodium fluoride (NaF) for 30 days increased the number of cell death, chromosomal aberrations (CAs) and 'cells with chromatid breaks' (aberrant cells) compared with control. The present study was intended to determine whether the fluoride (F)-induced genotoxicity could be reduced by substituting high F-containing water after 30 days with safe drinking water, containing 0.1 mg F ions l(-1). A significant fall in percentage of CAs and aberrant cells after withdrawal of F-treatment following 30 days of safe water treatment in mice was observed which was highest after 90 days, although their levels still remained significantly high compared with the control group. This observation suggests that F-induced genotoxicity could be reduced by substituting high F-containing water with safe drinking water. Further study is warranted with different doses and extended treatment of safe water to determine whether the induced damages could be completely reduced or not.

  10. A piezoelectric motor using flexural vibration of a thin piezoelectric membrane.

    Science.gov (United States)

    Lamberti, N; Iula, A; Pappalardo, M

    1998-01-01

    This paper describes a new implementation of a disk-type piezoelectric motor, whose stator is a commercial available piezomembrane composed of a nickel alloy disk to which a piezoceramic disk is bonded. The two disks are concentric, and the total thickness is very small. Ultrasonic motors are based on the concept of driving a rotor by mechanical vibration excited on a stator, via the piezoelectric effect. The rotor is in contact with the stator, and the driving force is the frictional force between rotor and stator. To transform the mechanical vibration of the stator in the rotor rotation, a traveling wave must be excited on the stator surface. The proposed motor can be regarded as a disk-type, single wavelength motor in which the traveling wave is due to the natural flexural vibration of the piezomembrane at low frequency. The behavior of the stator is analyzed both theoretically, by using the theory of isotropic and homogeneous vibrating plates, and by means of a commercial finite element computer code, finding a good agreement with the experimental results. The main features of the motor are very small thickness, appreciable torque, and high speed, obtained with low input power at low voltage; the intended application is to substitute the moving-coil in analogic instrumentation.

  11. Piezoelectric polymers as biomaterials for tissue engineering applications.

    Science.gov (United States)

    Ribeiro, Clarisse; Sencadas, Vítor; Correia, Daniela M; Lanceros-Méndez, Senentxu

    2015-12-01

    Tissue engineering often rely on scaffolds for supporting cell differentiation and growth. Novel paradigms for tissue engineering include the need of active or smart scaffolds in order to properly regenerate specific tissues. In particular, as electrical and electromechanical clues are among the most relevant ones in determining tissue functionality in tissues such as muscle and bone, among others, electroactive materials and, in particular, piezoelectric ones, show strong potential for novel tissue engineering strategies, in particular taking also into account the existence of these phenomena within some specific tissues, indicating their requirement also during tissue regeneration. This referee reports on piezoelectric materials used for tissue engineering applications. The most used materials for tissue engineering strategies are reported together with the main achievements, challenges and future needs for research and actual therapies. This review provides thus a compilation of the most relevant results and strategies and a start point for novel research pathways in the most relevant and challenging open questions.

  12. Regulation of Bone Metabolism

    Science.gov (United States)

    Shahi, Maryam; Peymani, Amir; Sahmani, Mehdi

    2017-01-01

    Bone is formed through the processes of endochondral and intramembranous ossification. In endochondral ossification primary mesenchymal cells differentiate to chondrocytes and then are progressively substituted by bone, while in intramembranous ossification mesenchymal stem cells (MSCs) differentiate directly into osteoblasts to form bone. The steps of osteogenic proliferation, differentiation, and bone homeostasis are controlled by various markers and signaling pathways. Bone needs to be remodeled to maintain integrity with osteoblasts, which are bone-forming cells, and osteoclasts, which are bone-degrading cells.In this review we considered the major factors and signaling pathways in bone formation; these include fibroblast growth factors (FGFs), bone morphogenetic proteins (BMPs), wingless-type (Wnt) genes, runt-related transcription factor 2 (RUNX2) and osteoblast-specific transcription factor (osterix or OSX). PMID:28367467

  13. Regulation of Bone Metabolism.

    Science.gov (United States)

    Shahi, Maryam; Peymani, Amir; Sahmani, Mehdi

    2017-04-01

    Bone is formed through the processes of endochondral and intramembranous ossification. In endochondral ossification primary mesenchymal cells differentiate to chondrocytes and then are progressively substituted by bone, while in intramembranous ossification mesenchymal stem cells (MSCs) differentiate directly into osteoblasts to form bone. The steps of osteogenic proliferation, differentiation, and bone homeostasis are controlled by various markers and signaling pathways. Bone needs to be remodeled to maintain integrity with osteoblasts, which are bone-forming cells, and osteoclasts, which are bone-degrading cells.In this review we considered the major factors and signaling pathways in bone formation; these include fibroblast growth factors (FGFs), bone morphogenetic proteins (BMPs), wingless-type (Wnt) genes, runt-related transcription factor 2 (RUNX2) and osteoblast-specific transcription factor (osterix or OSX).

  14. Bar piezoelectric ceramic transformers.

    Science.gov (United States)

    Erhart, Jiří; Pulpan, Půlpán; Rusin, Luboš

    2013-07-01

    Bar-shaped piezoelectric ceramic transformers (PTs) working in the longitudinal vibration mode (k31 mode) were studied. Two types of the transformer were designed--one with the electrode divided into two segments of different length, and one with the electrodes divided into three symmetrical segments. Parameters of studied transformers such as efficiency, transformation ratio, and input and output impedances were measured. An analytical model was developed for PT parameter calculation for both two- and three-segment PTs. Neither type of bar PT exhibited very high efficiency (maximum 72% for three-segment PT design) at a relatively high transformation ratio (it is 4 for two-segment PT and 2 for three-segment PT at the fundamental resonance mode). The optimum resistive loads were 20 and 10 kΩ for two- and three-segment PT designs for the fundamental resonance, respectively, and about one order of magnitude smaller for the higher overtone (i.e., 2 kΩ and 500 Ω, respectively). The no-load transformation ratio was less than 27 (maximum for two-segment electrode PT design). The optimum input electrode aspect ratios (0.48 for three-segment PT and 0.63 for two-segment PT) were calculated numerically under no-load conditions.

  15. Disc piezoelectric ceramic transformers.

    Science.gov (United States)

    Erhart, Jirií; Půlpán, Petr; Doleček, Roman; Psota, Pavel; Lédl, Vít

    2013-08-01

    In this contribution, we present our study on disc-shaped and homogeneously poled piezoelectric ceramic transformers working in planar-extensional vibration modes. Transformers are designed with electrodes divided into wedge, axisymmetrical ring-dot, moonie, smile, or yin-yang segments. Transformation ratio, efficiency, and input and output impedances were measured for low-power signals. Transformer efficiency and transformation ratio were measured as a function of frequency and impedance load in the secondary circuit. Optimum impedance for the maximum efficiency has been found. Maximum efficiency and no-load transformation ratio can reach almost 100% and 52 for the fundamental resonance of ring-dot transformers and 98% and 67 for the second resonance of 2-segment wedge transformers. Maximum efficiency was reached at optimum impedance, which is in the range from 500 Ω to 10 kΩ, depending on the electrode pattern and size. Fundamental vibration mode and its overtones were further studied using frequency-modulated digital holographic interferometry and by the finite element method. Complementary information has been obtained by the infrared camera visualization of surface temperature profiles at higher driving power.

  16. Cryogenic Piezoelectric Actuator

    Science.gov (United States)

    Jiang, Xiaoning; Cook, William B.; Hackenberger, Wesley S.

    2009-01-01

    In this paper, PMN-PT single crystal piezoelectric stack actuators and flextensional actuators were designed, prototyped and characterized for space optics applications. Single crystal stack actuators with footprint of 10 mm x10 mm and the height of 50 mm were assembled using 10 mm x10mm x0.15mm PMN-PT plates. These actuators showed stroke > 65 - 85 microns at 150 V at room temperature, and > 30 microns stroke at 77 K. Flextensional actuators with dimension of 10mm x 5 mm x 7.6 mm showed stroke of >50 microns at room temperature at driving voltage of 150 V. A flextensional stack actuator with dimension of 10 mm x 5 mm x 47 mm showed stroke of approx. 285 microns at 150 V at room temperature and > 100 microns at 77K under driving of 150 V should be expected. The large cryogenic stroke and high precision of these actuators are promising for cryogenic optics applications.

  17. New Swallowing Evaluation Using Piezoelectricity in Normal Individuals.

    Science.gov (United States)

    Sogawa, Yuichiro; Kimura, Shinji; Harigai, Toru; Sakurai, Naoki; Toyosato, Akira; Nishikawa, Taro; Inoue, Makoto; Murasawa, Akira; Endo, Naoto

    2015-12-01

    This study aimed to elucidate the relationship between the piezoelectric waveform latency, hyoid bone movement, surface electromyogram (sEMG), and the pharyngeal transit time (PTT) during swallowing. Forty-one healthy subjects were divided into three age groups: younger (20-39 years, n = 8), middle-aged (40-59 years, n = 9), and older (60-79 years, n = 24). Motion analysis of the hyoid bone using videofluorography (VF), waveform analysis of the front neck using piezoelectric films, and sEMG of the suprahyoid muscle group were performed simultaneously. Latencies of the three movement phases were defined as upward (VFS1), forward (VFS2), and returning to starting position (VFS3). The three phases of the piezoelectric waveform-from wave initiation of the negative wave to the start of the second deep negative wave; from the start of the second deep negative wave to the start of the last positive wave (SLPW); and from the SLPW to the end of the last positive wave-were defined as PS1, PS2, and PS3, respectively. VFS1-3 and PS1-3 were significantly correlated. VFS1 and PS1 latencies were significantly longer with thick liquid than with thin liquid. VFS2, PS1, and PS2 latencies were longer in the older group than in the other two groups. The start of PS1 was nearly equal to those of sEMG and VFS1. Bolus arrival time in the valleculae was statistically equal to the end of the PS1 with both thin and thick liquids. To establish the swallowing screening using Piezoelectric film, further investigation is necessary in the dysphagia patients.

  18. Solvent substitution

    Energy Technology Data Exchange (ETDEWEB)

    1990-01-01

    The DOE Environmental Restoration and Waste Management Office of Technology Development and the Air Force Engineering and Services Center convened the First Annual International Workshop on Solvent Substitution on December 4--7, 1990. The primary objectives of this joint effort were to share information and ideas among attendees in order to enhance the development and implementation of required new technologies for the elimination of pollutants associated with industrial use of hazardous and toxic solvents; and to aid in accelerating collaborative efforts and technology transfer between government and industry for solvent substitution. There were workshop sessions focusing on Alternative Technologies, Alternative Solvents, Recovery/Recycling, Low VOC Materials and Treatment for Environmentally Safe Disposal. The 35 invited papers presented covered a wide range of solvent substitution activities including: hardware and weapons production and maintenance, paint stripping, coating applications, printed circuit boards, metal cleaning, metal finishing, manufacturing, compliance monitoring and process control monitoring. This publication includes the majority of these presentations. In addition, in order to further facilitate information exchange and technology transfer, the US Air Force and DOE solicited additional papers under a general Call for Papers.'' These papers, which underwent review and final selection by a peer review committee, are also included in this combined Proceedings/Compendium. For those involved in handling, using or managing hazardous and toxic solvents, this document should prove to be a valuable resource, providing the most up-to-date information on current technologies and practices in solvent substitution. Individual papers are abstracted separated.

  19. Giant piezoelectric response in piezoelectric/dielectric superlattices due to flexoelectric effect

    Science.gov (United States)

    Liu, Chang; Wu, Huaping; Wang, Jie

    2016-11-01

    Flexoelectricity describes the linear response of electrical polarization to a strain gradient, which can be used to enhance the piezoelectric effect of piezoelectric material or realize the piezoelectric effect in nonpiezoelectric materials. Here, we demonstrate from thermodynamics theory that a giant piezoelectric effect exists in piezoelectric/dielectric superlattices due to flexoelectric effect. The apparent piezoelectric coefficient is calculated from the closed-form of analytical expression of the polarization distribution in the piezoelectric/dielectric superlattice subjected to a normal stress, in which the flexoelectric effect is included. It is found that there exists a strong nonlinear coupling between the flexoelectric and piezoelectric effects, which significantly enhances the apparent piezoelectric coefficient in the piezoelectric/dielectric superlattice. For a specific thickness ratio of the piezoelectric and dielectric layers, the enhanced apparent piezoelectric coefficient in the superlattice is ten times larger than that of its pure piezoelectric counterpart. The present work suggests an effective way to obtain giant apparent piezoelectric effect in piezoelectric/dielectric superlattices through flexoelectric effect.

  20. Piezoelectric nanomaterials for biomedical applications

    CERN Document Server

    Menciassi, Arianna

    2012-01-01

    Nanoscale structures and materials have been explored in many biological applications because of their novel and impressive physical and chemical properties. Such properties allow remarkable opportunities to study and interact with complex biological processes. This book analyses the state of the art of piezoelectric nanomaterials and introduces their applications in the biomedical field. Despite their impressive potentials, piezoelectric materials have not yet received significant attention for bio-applications. This book shows that the exploitation of piezoelectric nanoparticles in nanomedicine is possible and realistic, and their impressive physical properties can be useful for several applications, ranging from sensors and transducers for the detection of biomolecules to “sensible” substrates for tissue engineering or cell stimulation.

  1. Note: Direct piezoelectric effect microscopy.

    Science.gov (United States)

    Mori, T J A; Stamenov, P; Dorneles, L S

    2015-07-01

    An alternative method for investigating piezoelectric surfaces is suggested, exploiting the direct piezoeffect. The technique relies on acoustic (ultrasonic) excitation of the imaged surface and mapping of the resulting oscillatory electric potential. The main advantages arise from the spatial resolution of the conductive scanning probe microscopy in combination with the relatively large magnitude of the forward piezo signal Upf, which can be of the order of tens of mV even for non-ferroelectric piezoelectric materials. The potency of this experimental strategy is illustrated with measurements on well-crystallized quartz surfaces, where Upf ∼ 50 mV, for a piezoelectric coefficient of d33 = - 2.27  ×  10(-12) m/V, and applied stress of about T3 ∼ 5.7 kPa.

  2. A Study on the Meat and Bone Meal or Poultry By-product Meal as Protein Substitutes of Fishmeal in Concentrated Diets for Paralichthys olivaceus

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    A study was conducted to evaluate the effects of meat and bone meal (MBM) and poultry by-product meal (PBM) as the replacement of fishmeal in the diets on the growth performance, survival and apparent digestibility coefficient (ADC) of Japanese flounder (Paralichthys olivaceus). The experimental diets included 0%, 20%, 40%, 60% and 80% MBM or PBM replacement of total fishmeal respectively. All diets were iso-nitrogenous and isocaloric. The results showed that there are no significant differences (P>0.05) in growth performance among the treatments fed with 0%-60% MBM replacement of fishmeal, while the percent weight gain (WG,%), body length gain (BLG, %) and ADC significantly decrease when fishmeal is replaced by 80% MBM. The result showed also that there are no significant differences (P>0.05) in growth performance and ADC among all treatments fed with the diets with 0%-80% replacements of fishmeal with PBM.

  3. A study on the meat and bone meal or poultry by-product meal as protein substitutes of fishmeal in concentrated diets for Paralichthys olivaceus

    Science.gov (United States)

    Zhu, Wei; Mai, Kangsen; Zhang, Baigang; Hu, Yangjiang; Yu, Yu

    2006-01-01

    A study was conducted to evaluate the effects of meat and bone meal (MBM) and poultry by-product meal (PBM) as the replacement of fishmeal in the diets on the growth performance, survival and apparent digestibility coefficient (ADC) of Japanese flounder ( Paralichthys olivaceus). The experimental diets included 0%, 20%, 40%, 60% and 80% MBM or PBM replacement of total fishmeal respectively. All diets were iso-nitrogenous and isocaloric. The results showed that there are no significant differences ( P>0.05) in growth performance among the treatments fed with 0% 60% MBM replacement of fishmeal, while the percent weight gain (WG, %), body length gain (BLG, %) and ADC significantly decrease when fishmeal is replaced by 80% MBM. The result showed also that there are no significant differences ( P>0.05) in growth performance and ADC among all treatments fed with the diets with 0% 80% replacements of fishmeal with PBM.

  4. Direct observation of shear piezoelectricity in poly-l-lactic acid nanowires

    Directory of Open Access Journals (Sweden)

    Michael Smith

    2017-07-01

    Full Text Available Piezoelectric polymers are capable of interconverting mechanical and electrical energy, and are therefore candidate materials for biomedical applications such as sensors, actuators, and energy harvesters. In particular, nanowires of these materials are attractive as they can be unclamped, flexible and sensitive to small vibrations. Poly-l-lactic acid (PLLA nanowires have been investigated for their use in biological applications, but their piezoelectric properties have never been fully characterised, even though macroscopic films and fibres have been shown to exhibit shear piezoelectricity. This piezoelectric mode is particularly interesting for in vivo applications where shear forces are especially relevant, and is similar to what has been observed in natural materials such as bone and DNA. Here, using piezo-response force microscopy (PFM, we report the first direct observation of shear piezoelectricity in highly crystalline and oriented PLLA nanowires grown by a novel template-wetting method. Our results are validated using finite-element simulations and numerical analysis, which importantly and more generally allow for accurate interpretation of PFM signals in soft nanostructured materials. Our work opens up the possibility for the development of biocompatible and sustainable piezoelectric nanogenerators and sensors based on polymer nanowires.

  5. Direct observation of shear piezoelectricity in poly-l-lactic acid nanowires

    Science.gov (United States)

    Smith, Michael; Calahorra, Yonatan; Jing, Qingshen; Kar-Narayan, Sohini

    2017-07-01

    Piezoelectric polymers are capable of interconverting mechanical and electrical energy, and are therefore candidate materials for biomedical applications such as sensors, actuators, and energy harvesters. In particular, nanowires of these materials are attractive as they can be unclamped, flexible and sensitive to small vibrations. Poly-l-lactic acid (PLLA) nanowires have been investigated for their use in biological applications, but their piezoelectric properties have never been fully characterised, even though macroscopic films and fibres have been shown to exhibit shear piezoelectricity. This piezoelectric mode is particularly interesting for in vivo applications where shear forces are especially relevant, and is similar to what has been observed in natural materials such as bone and DNA. Here, using piezo-response force microscopy (PFM), we report the first direct observation of shear piezoelectricity in highly crystalline and oriented PLLA nanowires grown by a novel template-wetting method. Our results are validated using finite-element simulations and numerical analysis, which importantly and more generally allow for accurate interpretation of PFM signals in soft nanostructured materials. Our work opens up the possibility for the development of biocompatible and sustainable piezoelectric nanogenerators and sensors based on polymer nanowires.

  6. Relaxor-PT Single Crystal Piezoelectric Sensors

    Directory of Open Access Journals (Sweden)

    Xiaoning Jiang

    2014-07-01

    Full Text Available Relaxor-PbTiO3 piezoelectric single crystals have been widely used in a broad range of electromechanical devices, including piezoelectric sensors, actuators, and transducers. This paper reviews the unique properties of these single crystals for piezoelectric sensors. Design, fabrication and characterization of various relaxor-PT single crystal piezoelectric sensors and their applications are presented and compared with their piezoelectric ceramic counterparts. Newly applicable fields and future trends of relaxor-PT sensors are also suggested in this review paper.

  7. Surface modification of piezoelectric aluminum nitride with functionalizable organosilane adlayers

    Science.gov (United States)

    Chan, Edmund; Jackson, Nathan; Mathewson, Alan; Galvin, Paul; Alamin Dow, Ali B.; Kherani, Nazir P.; Blaszykowski, Christophe; Thompson, Michael

    2013-10-01

    The world of biosensors is expanding at a rapid pace with an ever-increasing demand for more sensitive miniaturized devices. Acoustic wave biosensors are not spared from this trend. In this domain, the search for enhanced sensitivity is increasingly oriented toward the rational design of new piezoelectric materials with superior properties to substitute for prevalent quartz. With respect to surface chemistry, construction of the biorecognition element, more often than not, requires the use of bifunctional molecules that can spontaneously assemble on the substrate and form organic surfaces readily biofunctionalizable in a subsequent, ideally single step. In this context, we present herein the surface modification of aluminum nitride (AlN) with alkyltrichlorosilane cross-linking molecules bearing a functionalizable benzenethiosulfonate moiety. This latter feature is next demonstrated through the straightforward, preactivation-free immobilization of thiolated biotin probes. To date, AlN has only received little attention in the field of piezoelectric biosensors despite its many attractive properties and the perspective to operate devices at ultra-high frequencies (GHz) with unprecedented sensitivity. To our knowledge, this work describes one of the first examples of direct surface derivatization of AlN with bifunctional trichlorosilane molecules. It also constitutes a first step toward the development of electrodeless GHz piezoelectric biosensing platforms based on AlN and trichlorosilane surface chemistry.

  8. Substitutos ósseos comparados ao enxerto ósseo autólogo em cirurgia ortopédica: revisão sistemática da literatura Bone graft substitutes compared to autologous bone graft in orthopedic surgery: systematic literature review

    Directory of Open Access Journals (Sweden)

    José Luís Amim Zabeu

    2008-03-01

    Full Text Available OBJETIVO: Identificar, a partir de revisão sistematizada da literatura, estudos clínicos com nível de evidência 1 comparando substitutos ósseos ao enxerto autólogo. MÉTODOS: Realizada busca eletrônica de artigos que comparassem o uso do enxerto ósseo autólogo a um substituto ósseo em cirurgia ortopédica. Foram considerados como critérios de elegibilidade ensaios clínicos prospectivos e randomizados em cirurgia ortopédica, com casuística mínima de 20 pacientes, envolvendo ossos da coluna vertebral ou esqueleto apendicular, publicados entre janeiro de 1990 e janeiro de 2006. RESULTADOS: Foram identificados 22 trabalhos, todos em língua inglesa, dos quais cinco compararam enxerto autólogo ao homólogo, sete envolveram uso de proteína morfogenética do tipo 2 (BMP-2, em três foi avaliada a proteína morfogenética do tipo 7 (BMP- 7 e sete utilizaram biocerâmicas, como hidroxiapatita, fosfato tricálcio e sulfato de cálcio. Os resultados mais sugestivos da equivalência com o enxerto autólogo se deram nos trabalhos com BMP-2 em cirurgia da coluna vertebral, embora diversos questionamentos possam ser feitos em relação a estes e aos demais estudos analisados, referentes a métodos e possíveis conflitos de interesses. CONCLUSÃO: Existem poucos estudos com alto nível de evidência que demonstrem a aplicabilidade clínica dos substitutos ósseos atualmente existentes.OBJECTIVE: Based on a systematic literature review, to identify studies with level of evidence 1 to compare bone graft substitutes to autologous bone grafts. METHODS: An electronic survey of papers comparing the use of autologous bone graft and a bone graft substitute in orthopedic surgery was performed. Inclusion criteria considered were prospective and randomized clinical trials in orthopedic surgery, with a minimum of 20 patients, involving spine or appendicular skeleton bones, published between January 1990 and January 2006. RESULTS: 22 papers were identified

  9. Sensory Substitution

    Science.gov (United States)

    Verrillo, Ronald T.

    The idea that the cutaneous surface may be employed as a substitute for the eyes and ears is by no means a modern notion. Although the sense of touch has long been considered as a surrogate for both the visual and auditory modalities, the focus of this chapter will be on the efforts to develop a tactile substitute for hearing, especially that of human speech. The visual system is our primary means of processing information about environmental space such as orientation, distance, direction and size. It is much less effective in making temporal discriminations. The auditory system is unparalleled in processing information that involves rapid sequences of temporal events, such as speech and music. The tactile sense is capable of processing both spatial and temporal information although not as effective in either domain as the eye or the ear.

  10. General solutions for special orthotropic piezoelectric media

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    This paper presents the forms of the general solution for general anisotropic piezoelectric media starting from the basic equations of piezoelasticity by using the operator method introduced by Lur'e (1964), and gives the analytical form of the general solution for special orthotropic piezoelectric media. This paper uses the non-uniqueness of the general solution to obtain the generalized LHN solution and the generalized E-L solution for special orthotropic piezoelectric media. When the special orthotropic piezoelectric media degenerate to transversely piezoelectric media, the solution given by this paper degenerates to the solution for transversely isotropic piezoelectric media accordingly, so that this paper generalized the results in transversely isotropic piezoelectric media.

  11. Substituting complements

    OpenAIRE

    Dari-Mattiacci, G.; Parisi, F.; Heller, M.

    2009-01-01

    The presence of multiple sellers in the provision of (nonsubstitutable) complementary goods leads to outcomes that are worse than those generated by a monopoly (with a vertically integrated production of complements), a problem known in the economic literature as complementary oligopoly and recently popularized in the legal literature as the tragedy of the anticommons. We ask the following question: how many substitutes for each complement are necessary to render the presence of multiple sell...

  12. Applications of piezoelectric surgery in endodontic surgery: a literature review.

    Science.gov (United States)

    Abella, Francesc; de Ribot, Joan; Doria, Guillermo; Duran-Sindreu, Fernando; Roig, Miguel

    2014-03-01

    Piezosurgery (piezoelectric bone surgery) devices were developed to cut bone atraumatically using ultrasonic vibrations and to provide an alternative to the mechanical and electrical instruments used in conventional oral surgery. Indications for piezosurgery are increasing in oral and maxillofacial surgery, as in other disciplines, such as endodontic surgery. Key features of piezosurgery instruments include their ability to selectively cut bone without damaging adjacent soft tissue, to provide a clear operative field, and to cut without generating heat. Although piezosurgery instruments can be used at most stages of endodontic surgery (osteotomy, root-end resection, and root-end preparation), no published data are available on the effect of piezosurgery on the outcomes of endodontic surgery. To our knowledge, no study has evaluated the effect of piezosurgery on root-end resection, and only 1 has investigated root-end morphology after retrograde cavity preparation using piezosurgery. We conducted a search of the PubMed and Cochrane databases using appropriate terms and keywords related to the use and applications of piezoelectric surgery in endodontic surgery. A hand search also was conducted of issues published in the preceding 2 years of several journals. Two independent reviewers obtained and analyzed the full texts of the selected articles. A total of 121 articles published between January 2000 and December 2013 were identified. This review summarizes the operating principles of piezoelectric devices and outlines the applications of piezosurgery in endodontic surgery using clinical examples. Piezosurgery is a promising technical modality with applications in several aspects of endodontic surgery, but further studies are necessary to determine the influence of piezosurgery on root-end resection and root-end preparation. Copyright © 2014 American Association of Endodontists. Published by Elsevier Inc. All rights reserved.

  13. A study on the meat and bone meal and poultry by-product meal as protein substitutes of fish meal in practical diets for Litopenaeus vannamei juveniles

    Science.gov (United States)

    Zhu, Wei; Mai, Kangsen; Zhang, Baigang; Wang, Fuzhen; Yu, Yu

    2004-10-01

    A study was conducted to evaluate the effects of meat and bone meal (MBM) and poultry by-product meal (PBM) as the replacement of fish meal in the diets on the growth performance, survival and apparent digestibility coefficients (ADC) of Litopenaeus vannamei. The basal diets were formulated with 22% fish meal and other ingredients which provided about 40% protein and 9% lipid in the diet. The experimental diets included MBM or PBM to replace 0, 20%, 40%, 60% and 80% of total fish meal respectively. All diets were iso-nitrogenous and isocaloric in gross terms. The results showed that there were no significant differences (Pτ;0.05) in growth performance and ADC among the treatments fed with the diets in which 0 60% fish meal had been replaced with MBM, while the percent weight gain (WG, %), body length gain (BLG, %) and ADC significantly decreased when the MBM was up to 80% of the fish meal. There were no significant differences (Pτ;0.05) in growth performance and ADC among all the treatments fed with the diets in which 0 80% fish meal had been replaced with PBM.

  14. A Study on the Meat and Bone Meal and Poultry By-product Meal as Protein Substitutes of Fish Meal in Practical Diets for Litopenaeus vannamei Juveniles

    Institute of Scientific and Technical Information of China (English)

    ZHU Wei; MAI Kangsen; ZHANG Baigang; WANG Fuzhen; YU Yu

    2004-01-01

    A study was conducted to evaluate the effects of meat and bone meal(MBM)and poultry by-product meal(PBM)as the replacement of fish meal in the diets on the growth performance, survival and apparent digestibility coefficients(ADC)of Litopenaeus vannamei. The basal diets were formulated with 22% fish meal and other ingredients which provided about 40% protein and 9% lipid in the diet. The experimental diets included MBM or PBM to replace 0, 20%, 40%, 60% and 80% of total fish meal respectively. All diets were iso-nitrogenous and isocaloric in gross terms. The results showed that there were no significant differences(P>0.05)in growth performance and ADC among the treatments fed with the diets in which 0-60% fish meal had been replaced with MBM, while the percent weight gain(WG,%), body length gain(BLG,%)and ADC significantly decreased when the MBM was up to 80% of the fish meal. There were no significant differences(P>0.05)in growth performance and ADC among all the treatments fed with the diets in which 0-80% fish meal had been replaced with PBM.

  15. Addition of enamel matrix derivatives to bone substitutes for the treatment of intrabony defects: A systematic review, meta-analysis and trial sequential analysis.

    Science.gov (United States)

    Troiano, Giuseppe; Laino, Luigi; Zhurakivska, Khrystyna; Cicciù, Marco; Lo Muzio, Lorenzo; Lo Russo, Lucio

    2017-07-01

    In order to enhance clinical improvement of intrabony defects, the addition of enamel matrix derivatives (EMD) to bone substitues (BS) has been investigated. The aim of this systematic review is to figure out whether such a combination, in comparison to the treatment with BS alone has beneficial effects on the following outcomes: clinical attachment level (CAL) gain, probing depth (PD) reduction and recession (REC). Electronic databases (PUBMED, SCOPUS, EBSCO Host Research Databases and Web of Knowledge) were searched for randomized controlled trials in humans addressing the use of a combination of BS and EMD versus a control group with BS alone for the treatment of intrabony defects, with a minimum of 6 months of follow-up; meta-analysis and trial sequential analysis were then performed. From a total of 1,197 records screened by title and abstract, nine studies were read full-text and five out of them included in the meta-analysis. No significant differences have been demonstrated both for CAL gain, PD reduction and REC between test and control groups. In the treatment of intrabony defects, the addition of EMD to BS seems to be not beneficial in terms of CAL gain, PD reduction and REC changes. However, such results should be considered with caution because of the small number of studies included in the meta-analysis and their heterogeneity. © 2017 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

  16. Cylindrical Piezoelectric Fiber Composite Actuators

    Science.gov (United States)

    Allison, Sidney G.; Shams, Qamar A.; Fox, Robert L.

    2008-01-01

    The use of piezoelectric devices has become widespread since Pierre and Jacques Curie discovered the piezoelectric effect in 1880. Examples of current applications of piezoelectric devices include ultrasonic transducers, micro-positioning devices, buzzers, strain sensors, and clocks. The invention of such lightweight, relatively inexpensive piezoceramic-fiber-composite actuators as macro fiber composite (MFC) actuators has made it possible to obtain strains and displacements greater than those that could be generated by prior actuators based on monolithic piezoceramic sheet materials. MFC actuators are flat, flexible actuators designed for bonding to structures to apply or detect strains. Bonding multiple layers of MFC actuators together could increase force capability, but not strain or displacement capability. Cylindrical piezoelectric fiber composite (CPFC) actuators have been invented as alternatives to MFC actuators for applications in which greater forces and/or strains or displacements may be required. In essence, a CPFC actuator is an MFC or other piezoceramic fiber composite actuator fabricated in a cylindrical instead of its conventional flat shape. Cylindrical is used here in the general sense, encompassing shapes that can have circular, elliptical, rectangular or other cross-sectional shapes in the planes perpendicular to their longitudinal axes.

  17. Vacuum mounting for piezoelectric transducers

    Science.gov (United States)

    Tiede, D. A.

    1977-01-01

    Special housing couples piezoelectric transducers to nonporous surfaces for ultrasonic or acoustic-emission testing. Device, while providing sound isolation on flat or nonflat surfaces, can be attached and detached quickly. Vacuum sealing mechanism eliminates need for permanent or semipermanent bonds, viscous coupling liquids, weights, magnets, tape, or springs ordinarily used.

  18. Circuit for Driving Piezoelectric Transducers

    Science.gov (United States)

    Randall, David P.; Chapsky, Jacob

    2009-01-01

    The figure schematically depicts an oscillator circuit for driving a piezoelectric transducer to excite vibrations in a mechanical structure. The circuit was designed and built to satisfy application-specific requirements to drive a selected one of 16 such transducers at a regulated amplitude and frequency chosen to optimize the amount of work performed by the transducer and to compensate for both (1) temporal variations of the resonance frequency and damping time of each transducer and (2) initially unknown differences among the resonance frequencies and damping times of different transducers. In other words, the circuit is designed to adjust itself to optimize the performance of whichever transducer is selected at any given time. The basic design concept may be adaptable to other applications that involve the use of piezoelectric transducers in ultrasonic cleaners and other apparatuses in which high-frequency mechanical drives are utilized. This circuit includes three resistor-capacitor networks that, together with the selected piezoelectric transducer, constitute a band-pass filter having a peak response at a frequency of about 2 kHz, which is approximately the resonance frequency of the piezoelectric transducers. Gain for generating oscillations is provided by a power hybrid operational amplifier (U1). A junction field-effect transistor (Q1) in combination with a resistor (R4) is used as a voltage-variable resistor to control the magnitude of the oscillation. The voltage-variable resistor is part of a feedback control loop: Part of the output of the oscillator is rectified and filtered for use as a slow negative feedback to the gate of Q1 to keep the output amplitude constant. The response of this control loop is much slower than 2 kHz and, therefore, does not introduce significant distortion of the oscillator output, which is a fairly clean sine wave. The positive AC feedback needed to sustain oscillations is derived from sampling the current through the

  19. The First-Principle Calculation of La-doping Effect on Piezoelectricity in Tetragonal KNN Crystal

    Science.gov (United States)

    Zhang, Qiaoli; Zhu, Jiliang; Yuan, Daqing; Zhu, Bo; Wang, Mingsong; Zhu, Xiaohong; Fan, Ping; Zuo, Yi; Zheng, Yongnan; Zhu, Shengyun

    2012-05-01

    The La-dopping effect on the piezoelectricity in the K0.5Na0.5NbO3 (KNN) crystal with a tetragonal phase is investigated for the first time using the first-principle calculation based on density functional theory. The full potentiallinearized augumented plane wave plus local orbitals (APW-LO) method and the supercell method are used in the calculation for the KNN crystal with and without the La doping. The results show that the piezoelectricity originates from the strong hybridization between the Nb atom and the O atom, and the substitution of the K or Na atom by the La impurity atom introduces the anisotropic relaxation and enhances the piezoelectricity at first and then restrains the hybridization of the Nb-O atoms when the La doping content further increases.

  20. The First-Principle Calculation of La-doping Effect on Piezoelectricity in Tetragonal KNN Crystal

    Institute of Scientific and Technical Information of China (English)

    张乔丽; 朱基亮; 袁大庆; 朱波; 王明松; 朱小红; 范平; 左翼; 郑永男; 朱升云

    2012-01-01

    The La-dopping effect on the piezoelectricity in the K0.5Na0.5NbO3 (KNN) crystal with a tetragonal phase is investigated for the first time using the first-principle calculation based on density functional theory. The full potentiallinearized augumented plane wave plus local orbitals (APW-LO) method and the supercell method are used in the calculation for the KNN crystal with and without the La doping. The results show that the piezoelectricity originates from the strong hybridization between the Nb atom and the O atom, and the substitution of the K or Na atom by the La impurity atom introduces the anisotropic relaxation and enhances the piezoelectricity at first and then restrains the hybridization of the Nb-O atoms when the La doping content further increases.

  1. Static and dynamic analysis of a four-tube piezoelectric actuator.

    Science.gov (United States)

    Ma, Yuting; Feng, Zhihua; Pan, Chengliang; Kong, Fanrang

    2009-06-01

    Piezoelectric tubes with film electrodes on their outer and inner surfaces can be used to compose multitube actuators. The actuator of four piezoelectric tubes can substitute the traditional single-tube actuator with quartered electrodes which has been widely used in scanning probe microscopy and piezoelectric motors. In this article, the static deflection, static bending moment, resonant frequency, and dynamic deflection of the four-tube actuator are all studied in detail. The comparison between this actuator and the traditional single-tube actuator is also done and the results show that the four-tube actuator has better performances under certain conditions. The experiment results of a prototype actuator testified the validation of the analysis.

  2. High Power Piezoelectric Characterization for Piezoelectric Transformer Development

    Science.gov (United States)

    Ural, Seyit O.

    The major goal was to develop characterization techniques to identify and define guidelines to manufacture high power density actuators. We particularly aim at improving the strengths of piezoelectric transformers, namely the high efficiency, ease of manufacturing, low electromagnetic noise, and high power to weight ratio resulting in an adaptor application by identifying material limitations, geometrical limitations and offer guidelines to counter drawbacks limiting the power density. There are 3 losses present in piezoelectrics. Namely dielectric, elastic and piezoelectric losses. These losses can be calculated using mechanical quality factors of the resonating piezoelectric actuator. But in order to calculate all three losses, the mechanical quality factor for resonance and anti resonance need to be measured. Although the mechanical quality factor for resonance is conventionally measured, measurements in antiresonance have been ignored. Since there was no unique measurement technique to address antiresonance and resonance Q in one single sweep, in this study constant vibration velocity method was developed. During the constant vibration velocity measurement, the input electrical energy is monitored and significant differences between resonance and antiresonance drives are observed. For the same output work (identical vibration velocity) significant differences in the losses were observed. Thermographic images have shown increasing temperature differences for resonance and antiresonance nodal point temperatures, with higher vibration velocities. The theoretical evaluation identified the difference observed in the mechanical quality factors at resonance and antiresonance to stem from the piezoelectric loss. In order to investigate losses in the absence of thermal effects a transient characterization technique was adopted. The burst technique, originally developed for characterization of the mechanical quality factor at resonance, has been modified with a switch

  3. Artrodese na coluna cervical utilizando SICAP como substituto de enxerto ósseo Artrodesis en la columna cervical utilizando SICAP como sustituto de injerto óseo Cervical spine fusion utilizing silicated calcium phosphate bone graft substitute (SICAP

    Directory of Open Access Journals (Sweden)

    Juliano Fratezi

    2011-01-01

    Tech EE.UU, Reino Unido es un injerto óseo compuesto de calcio-fosfato con una sustitución de silicato en la estructura química, con una estructura tridimensional que parece hueso natural. MÉTODOS: 19 pacientes fueron sometidos a fusión ósea cervical y analizados retrospectivamente. La evaluación radiográfica y la evaluación clínica fueron realizadas utilizandose el cuestionario Neck Disability Index y la escala análoga del dolor (VAS pre y postoperación. RESULTADOS: El período promedio de seguimiento postoperatorio fue de 14 meses ± 5 meses (7-30 meses. Once pacientes fueron sometidos a fusión vía anterior; 5 pacientes vía posterior y 3 pacientes vía anterior y posterior. La revisión radiográfica mostró 19/19 (100% de fusión ósea, ningún caso presentó subsidencia, rotura o soltura de material de implante o movimiento en los niveles fusionados. Ningún ejemplo de osificación heterotópica o de crecimiento óseo intracanal fue observado. Clínicamente, el promedio de las puntuaciones del Neck Disability disminuyeron 13,3 puntos (promedio preop. de 34,5, postop. de 21,2, mejora de 39%, el promedio de VAS para dolor cervical disminuyó 2 puntos (2,7 preop. para 0,7 postop.; mejora de 74,1%. No fueron observadas complicaciones como infección, osteólisis o edema excesivo de las partes blandas. CONCLUSIÓN: Los resultados preliminares obtenidos en esta serie feuron estimulantes con el uso de SICaP como injerto óseo, con sólida fusión ósea obtenida en todos los casos y sin formación de osificación heterotópica o crecimiento de hueso intracanal. SIcaP demuestra ser un sustituto confiable para el injerto óseo autólogo en la columna cervical.OBJECTIVE: Bone graft substitutes have been developed to obviate the need for autograft from the iliac crest and its resultant complications. SiCaP (Actifuse, ApaTech US, UK is a calcium phosphate bone graft substitute with selective controlled silicate substitution in a patented 3-dimensional structure

  4. Recurrent multilocular mandibular giant cell granuloma in neurofibromatosis type 1: Evidence for second hit mutation of NF1 gene in the jaw lesion and treatment with curettage and bone substitute materials.

    Science.gov (United States)

    Friedrich, Reinhard E; Grob, Tobias J; Hollants, Silke; Zustin, Jozef; Spaepen, Marijke; Mautner, Victor F; Luebke, Andreas M; Hagel, Christian; Legius, Eric; Brems, Hilde

    2016-08-01

    Giant cell granuloma (GCG) of the jaw is a rare, well-known feature of neurofibromatosis type 1 (NF1), an inborn multisystem disorder. Recently, the development of GCG in NF1 was attributed to second hit mutations in the NF1 gene. The treatment of GCG is pragmatic with a preference for local curettage of lytic osseous areas. This report describes the surgical therapy of an NF1-affected female with multilocular mandibular GCG and hypodontia who additionally suffered from a brain tumour and Hashimoto's thyroiditis. Although local recurrence of GCG was noted, augmentation of the curetted cavities with a bone substitute in successive interventions successfully restored the extensive periradicular local defects and stabilised the teeth. A meticulous in vitro study of the GCG specimen revealed a second hit mutation in the NF1 gene in the GCG spindle-cells. This study contributes to the increasing knowledge of the molecular basis for GCG in the jaw of NF1 patients, indicating that it is a neoplasm.

  5. CT assisted biomimetic artificial bone des

    Institute of Scientific and Technical Information of China (English)

    WANG Xian-gang; ZHANG Chao-zong; GUO Zhi-ping; TIAN Jie-mo

    2001-01-01

    @@ In the recent years, bioceramic materials have been widely used in the clinics. They are mainly fabricated as the substitution of human hard tissue, such as artificial bone and false tooth. As a medical implant, those that have similar structure to human bone have better biocompatibility and osteoinductional property. So it is necessary to design bone model close to human bone.

  6. Bone tumor

    Science.gov (United States)

    Tumor - bone; Bone cancer; Primary bone tumor; Secondary bone tumor; Bone tumor - benign ... The cause of bone tumors is unknown. They often occur in areas of the bone that grow rapidly. Possible causes include: Genetic defects ...

  7. FLOW DIRECTION OF PIEZOELEC-TRIC PUMP WITH NOZZLE/DIFFUSER-ELEMENTS

    Institute of Scientific and Technical Information of China (English)

    Zhang Jianhui; Xia Qixiao; Hong Zhen; Onuki Akiyoshi

    2004-01-01

    The piezoelectric pump with nozzle/diffuser-elements, which oscillating form differing from regular volumetric reciprocating or rotating pumps because there are nozzle/diffuser-elements substituted for regular valves, is a new type pump whose actuator is a piezoelectric ceramal part with verse piezoelectric effect.In recent year, piezoelectric pump is paid increasing attention to because it is an ideal candidate in application in such area as medical health, mechanical tools and micro-mechanism.The fundamental research on it, however, is still not made through.Focuses on the phenomenon of different directions of flow among Germany pump, Chinese pump and Swiss pump, which are all fitted with nozzle/diffuser-elements, and analyzes the cone angle of nozzle/diffuser-elements based on the flow equation of valve-less piezoelectric pump with nozzle/diffuser-elements.As a result, the concepts of diffuser loss coefficient and loss coefficient are introduced to explain these phenomena, from which a discussion is given on the optimization of the cone angle of nozzle/diffuser-element aiming at the maximum of pump flow.

  8. Coupled improvement between thermoelectric and piezoelectric materials

    Science.gov (United States)

    Montgomery, David; Hewitt, Corey; Dun, Chaochao; Carroll, David

    A novel coupling effect in a thermoelectric and piezoelectric meta-structure is discussed. Thermo-piezoelectric generators (TPEGs) exhibit a synergistic effect that amplifies output voltage, and has been observed to increase piezoelectric voltages over 500% of initial values a time dependent thermoelectric/pyroelectric effect. The resulting improvement in voltage has been observed in carbon nanotubes as well as inorganics such as two-dimensional Bismuth Selenide platelets and Telluride nanorods thin-film thermoelectrics. TPEGs are built by integrating insulating layers of polyvinylidene fluoride (PVDF) piezoelectric films between flexible thin film p-type and n-type thermoelectrics. The physical phenomena arising in the interaction between thermoelectric and piezoelectrics is discussed and a model is presented to quantify the expected coupling voltage as a function of stress, thermal gradient, and different thermoelectric materials. TPEG are ideal to capture waste heat and vibrational energy while creating larger voltages and minimizing space when compared with similar thermoelectric or piezoelectric generators.

  9. Piezoelectric Power Requirements for Active Vibration Control

    Science.gov (United States)

    Brennan, Matthew C.; McGowan, Anna-Maria Rivas

    1997-01-01

    This paper presents a method for predicting the power consumption of piezoelectric actuators utilized for active vibration control. Analytical developments and experimental tests show that the maximum power required to control a structure using surface-bonded piezoelectric actuators is independent of the dynamics between the piezoelectric actuator and the host structure. The results demonstrate that for a perfectly-controlled system, the power consumption is a function of the quantity and type of piezoelectric actuators and the voltage and frequency of the control law output signal. Furthermore, as control effectiveness decreases, the power consumption of the piezoelectric actuators decreases. In addition, experimental results revealed a non-linear behavior in the material properties of piezoelectric actuators. The material non- linearity displayed a significant increase in capacitance with an increase in excitation voltage. Tests show that if the non-linearity of the capacitance was accounted for, a conservative estimate of the power can easily be determined.

  10. Introduction to Piezoelectric Actuators and Transducers

    Science.gov (United States)

    2007-11-02

    1 Introduction to Piezoelectric Actuators and Transducers Kenji Uchino, International Center for Actuators and Transducers, Penn State University...REPORT DATE 00 JUN 2003 2. REPORT TYPE N/A 3. DATES COVERED - 4. TITLE AND SUBTITLE Introduction to Piezoelectric Actuators and Transducers...now used in various fields. The sound source is made from piezoelectric ceramics as well as magnetostrictive materials. Piezoceramics are generally

  11. Piezoelectric field in strained GaAs.

    Energy Technology Data Exchange (ETDEWEB)

    Chow, Weng Wah; Wieczorek, Sebastian Maciej

    2005-11-01

    This report describes an investigation of the piezoelectric field in strained bulk GaAs. The bound charge distribution is calculated and suitable electrode configurations are proposed for (1) uniaxial and (2) biaxial strain. The screening of the piezoelectric field is studied for different impurity concentrations and sample lengths. Electric current due to the piezoelectric field is calculated for the cases of (1) fixed strain and (2) strain varying in time at a constant rate.

  12. Heartbeat detection system using piezoelectric transducer

    Science.gov (United States)

    Hamonangan, Yosua; Purnamaningsih, Wigajatri

    2017-02-01

    This paper presents a simple piezoelectric based heartbeat detection system. The signal produced by the piezoelectric will undergo signal conditioning and then converted into digital data by Arduino Nano. Using serial communication, the data will be sent to a computer for display and further analysis. The detection of heartbeat is carried out on three locations; wrist, chest, and diaphragm. From the measurement results, it is shown that the system work best when the piezoelectric is placed on wrist.

  13. Piezoelectric actuator for pulsating jets

    Science.gov (United States)

    Brissaud, Michel; Gonnard, Paul; Bera, Jean-Christophe; Sunyach, Michel

    2000-08-01

    Recent researches in aeronautics showed that fluidic actuator systems could offer possibilities for drag reduction and lift improvement. To this end many actuator types were designed. This paper deals with the design, fabrication and test of piezoelectric actuator in order to generate pulsated jets normal to a surface and control air flow separation. It is based on the flexural displacement of a rectangular metal plate clamped on one of its large edge. Piezoelectric patches cemented on the plate were used for driving into vibration the actuator. Experimental measurements show that pulsed flow velocities are adjustable from 1.5m/s to 35m/s through a 100x1mm2 slit andwithin a 100 to 400 Hz frequency range. Prototype provides the jet performances classically required for active control flow.

  14. Piezoelectric Vibration Energy Harvesting Device Combined with Damper

    Directory of Open Access Journals (Sweden)

    Hung-I Lu

    2014-05-01

    Full Text Available Piezoelectricity is a type of material that enables mechanical energy and electrical energy to be interchangeable, which can be divided into positive piezoelectric effect and inverse piezoelectric effect. The positive piezoelectric effect is that the electric dipole moment of material generates changes when the piezoelectric material is subjected to pressure, resulting in electrical energy. Conversely, the inverse piezoelectric effect is the process of electrical energy converted into mechanical energy.

  15. 重组人工骨修复实验性骨缺损影像学评价%Imaginological study on resombinant artificial bone substitute for experimental bone defects

    Institute of Scientific and Technical Information of China (English)

    宋会平; 刘强; 原林; 李宝兴

    2006-01-01

    [目的]探讨重组人胰岛素样生长因子-1(recombinant human insulinlike growth factor-1,rhIGF-1)/珊瑚羟基磷灰石(coralline hydroxyapatite,CHA)/自体红骨髓(autogeneous red bone marrow,ARBM)复合修复骨缺损的能力.[方法]成年中国家兔54只,随机分为3组,制成双侧桡骨中段11 mm骨-骨膜全层缺损模型,每组18只,每组动物左右两侧缺损分别随机植入2种不同材料:1组两侧分别植入材料A(CHA/ARBM/rhIGF-1)和B(CHA/ARBM);2组植入C(CHA/rhIGF-1)和D(CHA);3组植入E(自体皮质骨)和F(缺损旷置).术后行大体、X线(2、4、8、12周)和99mTc-MDP骨扫描(12周)观察.[结果]A组X线片显示桥接骨痂生长良好,12周时缺损修复.12周99mTc-MDP骨显像示A和E组修复区高度核浓聚.[结论]CHA/ARBM/rhIGF-1重组人工骨移植可协同实现骨传导、骨诱导和骨再生作用,促进骨缺损重建.

  16. A Piezoelectric Cryogenic Heat Switch

    Science.gov (United States)

    Jahromi, Amir E.; Sullivan, Dan F.

    2014-01-01

    We have measured the thermal conductance of a mechanical heat switch actuated by a piezoelectric positioner, the PZHS (PieZo electric Heat Switch), at cryogenic temperatures. The thermal conductance of the PZHS was measured between 4 K and 10 K, and on/off conductance ratios greater than 100 were achieved when the positioner applied its maximum force of 8 N. We discuss the advantages of using this system in cryogenic applications, and estimate the ultimate performance of an optimized PZHS.

  17. Piezoelectric Energy Harvesting for Roadways

    OpenAIRE

    Xiong, Haocheng

    2015-01-01

    Energy harvesting technologies have drawn much attention as an alternative power source of roadway accessories in different scales. Piezoelectric energy harvesting consisting of PZT piezoceramic disks sealed in a protective package is developed in this work to harness the deformation energy of pavement induced by traveling vehicles and generate electrical energy. Six energy harvesters are fabricated and installed at the weigh station on I-81 at Troutville, VA to perform on-site evaluation. T...

  18. Bone cysts: unicameral and aneurysmal bone cyst.

    Science.gov (United States)

    Mascard, E; Gomez-Brouchet, A; Lambot, K

    2015-02-01

    Simple and aneurysmal bone cysts are benign lytic bone lesions, usually encountered in children and adolescents. Simple bone cyst is a cystic, fluid-filled lesion, which may be unicameral (UBC) or partially separated. UBC can involve all bones, but usually the long bone metaphysis and otherwise primarily the proximal humerus and proximal femur. The classic aneurysmal bone cyst (ABC) is an expansive and hemorrhagic tumor, usually showing characteristic translocation. About 30% of ABCs are secondary, without translocation; they occur in reaction to another, usually benign, bone lesion. ABCs are metaphyseal, excentric, bulging, fluid-filled and multicameral, and may develop in all bones of the skeleton. On MRI, the fluid level is evocative. It is mandatory to distinguish ABC from UBC, as prognosis and treatment are different. UBCs resolve spontaneously between adolescence and adulthood; the main concern is the risk of pathologic fracture. Treatment in non-threatening forms consists in intracystic injection of methylprednisolone. When there is a risk of fracture, especially of the femoral neck, surgery with curettage, filling with bone substitute or graft and osteosynthesis may be required. ABCs are potentially more aggressive, with a risk of bone destruction. Diagnosis must systematically be confirmed by biopsy, identifying soft-tissue parts, as telangiectatic sarcoma can mimic ABC. Intra-lesional sclerotherapy with alcohol is an effective treatment. In spinal ABC and in aggressive lesions with a risk of fracture, surgical treatment should be preferred, possibly after preoperative embolization. The risk of malignant transformation is very low, except in case of radiation therapy.

  19. High Reliability Cryogenic Piezoelectric Valve Actuator Project

    Data.gov (United States)

    National Aeronautics and Space Administration — Cryogenic fluid valves are subject to harsh exposure and actuators to drive these valves require robust performance and high reliability. DSM's piezoelectric...

  20. FLUTTER SUPPRESSION USING DISTRIBUTED PIEZOELECTRIC ACTUATORS

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    The Flutter suppression using distributed piezoelectric actuators has been analyzed and tested. In constructing the finite element equation, effects of piezoelectric matrices are investigated. LQG method is used in designing the control law. In reducing the order of the control law, both balance realization and LK methods are used. For the rational approximation of the unsteady aerodynamic forces LS method is improved. In determining the piezoelectric constants d31 a new dynamic response method is developed. Laser vibrameter is used to pick up the model response and in ground resonance test the model is excited by piezoelectric actuators. Reasonable agreement of the wind tunnel flutter suppression test with calculated results is obtained.

  1. Fabrication of Piezoelectric Cellulose Paper and Audio Application

    Institute of Scientific and Technical Information of China (English)

    Jung-Hwan Kim; Sungryul Yun; Joo-Hyung Kim; Jaehwan Kim

    2009-01-01

    We report the fabrication process of piezoelectric cellulose paper and the enhancement method of its piezoelectric property.Stretching method with different wet-drawing ratios was introduced to increase the piezoelectric property of cellulose paper during regeneration process. It is observed that the Young's modulus and the piezoelectric charge constants are very dependent on the drawing ratio and the direction of nanofibrils of piezoelectric paper. Using the enhanced piezoelectric property, we prove that the flexible regenerated piezoelectric cellulose can be applied to the potential acoustic applications such as thin piezoelectric paper speaker.

  2. AN EXPERIMENTAL STUDY ON RECOMBINANT ARTIFICIAL BONE SUBSTITUTE FOR REPAIRING SEGMENTAL BONE DEFECT IN RABBITS%重组人工骨移植修复节段性骨缺损的实验研究

    Institute of Scientific and Technical Information of China (English)

    宋会平; 刘强; 王志强; 李钢; 张立峰; 彭晨

    2005-01-01

    目的探讨重组人胰岛素样生长因子-1(recombinant human insulin-like growth factor 1,rhIGF-1)/珊瑚羟基磷灰石(coralline hydroxyapatite,CHA)/自体红骨髓(autogeneous red bone marrow ,ARBM)复合构建重组人工骨修复骨缺损的能力. 方法成年中国家兔54只,随机分为3组,每组18只.制成双侧桡骨干11 mm骨-骨膜全层缺损模型,每组动物双侧缺损分别随机植入两种不同材料,形成自体对照的实验组和对照组.1组:实验组(A组,植入CHA/ARBM/rhIGF-1)和对照组(B组,植入CHA/ARBM);2组:实验组(C组,植入CHA/ rhIGF-1)和对照组(D组,植入CHA);3组:实验组(E组,植入取自对侧相应缺损骨段的自体骨)和对照组(F组,缺损旷置).于术后2、4、8和12周行X线片观察、计算机图像分析、组织学观察和生物力学检测,比较各组修复骨缺损能力. 结果 A组在各时间点X线片及计算机图像分析均优于其它各组,差异有统计学意义(P0.05),但显著优于其它各组(P0.05),成骨效果低于A、B和E组.12周时F组缺损未修复. 结论 CHA/ARBM/rhIGF-1重组后可协同实现骨再生、骨传导和骨诱导三重促成骨功效,可替代自体骨移植,成为一种新型的复合活性人工骨.

  3. Stretched exponential relaxation of piezovoltages in wet bovine bone.

    Science.gov (United States)

    Xu, Lianyun; Hou, Zhende; Fu, Donghui; Qin, Qing-Hua; Wang, Yihan

    2015-01-01

    It is important to determine the amplitude and variation characteristics of piezovoltage in wet bone, which can, in turn, be taken as a basis for studying whether electrical signals induced by external forces can affect the growth of bone cells. This work measured the characteristics of piezoelectric effects under dynamic and static loading. The results show that the variations of piezovoltage in wet bone in both loading and load holding periods follow a stretched exponential relaxation law, and the relaxation time constants of the piezovoltages are much larger than those of dry bone. This finding means that the active time of piezovoltage in wet bone is much longer than that of dry bone. Regardless of the loading and load holding processes, continuously increasing deformation in wet bone caused piezoelectric charges to be continuously induced and increased the dielectric constant of wet bone along with the deformation process. In general, compared with piezovoltage in dry bone, that in wet bone had lower amplitude and could exist for a longer duration. It can be inferred, therefore, that piezoelectricity might create coupling with the streaming potential in bone by changing the thickness of the double electrode layer. Copyright © 2014 Elsevier Ltd. All rights reserved.

  4. High temperature, high power piezoelectric composite transducers.

    Science.gov (United States)

    Lee, Hyeong Jae; Zhang, Shujun; Bar-Cohen, Yoseph; Sherrit, Stewart

    2014-08-08

    Piezoelectric composites are a class of functional materials consisting of piezoelectric active materials and non-piezoelectric passive polymers, mechanically attached together to form different connectivities. These composites have several advantages compared to conventional piezoelectric ceramics and polymers, including improved electromechanical properties, mechanical flexibility and the ability to tailor properties by using several different connectivity patterns. These advantages have led to the improvement of overall transducer performance, such as transducer sensitivity and bandwidth, resulting in rapid implementation of piezoelectric composites in medical imaging ultrasounds and other acoustic transducers. Recently, new piezoelectric composite transducers have been developed with optimized composite components that have improved thermal stability and mechanical quality factors, making them promising candidates for high temperature, high power transducer applications, such as therapeutic ultrasound, high power ultrasonic wirebonding, high temperature non-destructive testing, and downhole energy harvesting. This paper will present recent developments of piezoelectric composite technology for high temperature and high power applications. The concerns and limitations of using piezoelectric composites will also be discussed, and the expected future research directions will be outlined.

  5. Experiments to Demonstrate Piezoelectric and Pyroelectric Effects

    Science.gov (United States)

    Erhart, Jirí

    2013-01-01

    Piezoelectric and pyroelectric materials are used in many current applications. The purpose of this paper is to explain the basic properties of pyroelectric and piezoelectric effects and demonstrate them in simple experiments. Pyroelectricity is presented on lead zirconium titanate (PZT) ceramics as an electric charge generated by the temperature…

  6. Variational principles for nonlinear piezoelectric materials

    Energy Technology Data Exchange (ETDEWEB)

    Rodriguez-Ramos, R.; Guinovart-Diaz, R. [Universidad de la Habana, Facultad de Matematica y Computacion, Vedado, Habana (Cuba); Pobedria, B.E. [Moscow State University M. V. Lomonosov, Composites Department, Moscow (Russian Federation); Padilla, P. [Universidad Nacional Autonoma de Mexico, Instituto de Investigaciones en Matematicas Aplicadas y en Sistemas (IIMAS), Cd. Universitaria, Mexico D.F. (Mexico); Bravo-Castillero, J. [Universidad de la Habana, Facultad de Matematica y Computacion, Vedado, Habana (Cuba); Campus Estado de Mexico. Division de Arquitectura e Ingenieria, Instituto Tecnologico de Estudios Superiores de Monterrey, Atizapan de Zaragoza, Estado de Mexico (Mexico); Maugin, G.A. [Universite Pierre et Marie Curie. Case 162, UMR 7607 CNRS, Laboratoire de Modelisation en Mecanique, Paris Cedex 05 (France)

    2004-12-01

    In the present paper, we consider the behavior of nonlinear piezoelectric materials by generalization for this case of the Hashin-Shtrikman variational principles. The new general formulation used here differs from others, because, it gives the possibility to evaluate the upper and lower Hashin-Shtrikman bounds for specific physical nonlinearities of piezoelectric materials. Geometrical nonlinearities are not considered. (orig.)

  7. Tailored piezoelectric thin films for energy harvester

    NARCIS (Netherlands)

    Wan, X.

    2013-01-01

    Piezoelectric materials are excellent materials to transfer mechanical energy into electrical energy, which can be stored and used to power other devices. PiezoMEMS is a good way to combine silicon wafer processing and piezoelectric thin film technology and lead to a variety of miniaturized and prem

  8. Special topics in the theory of piezoelectricity

    CERN Document Server

    Yang, Jiashi

    2009-01-01

    Piezoelectricity has been a steadily growing field, with recent advances made by researchers from applied physics, acoustics, materials science, and engineering. This collective work presents a comprehensive treatment of selected advanced topics in the subject. The book is written for an intermediate graduate level and is intended for researchers, mechanical engineers, and applied mathematicians interested in the advances and new applications in piezoelectricity.

  9. High Temperature, High Power Piezoelectric Composite Transducers

    Directory of Open Access Journals (Sweden)

    Hyeong Jae Lee

    2014-08-01

    Full Text Available Piezoelectric composites are a class of functional materials consisting of piezoelectric active materials and non-piezoelectric passive polymers, mechanically attached together to form different connectivities. These composites have several advantages compared to conventional piezoelectric ceramics and polymers, including improved electromechanical properties, mechanical flexibility and the ability to tailor properties by using several different connectivity patterns. These advantages have led to the improvement of overall transducer performance, such as transducer sensitivity and bandwidth, resulting in rapid implementation of piezoelectric composites in medical imaging ultrasounds and other acoustic transducers. Recently, new piezoelectric composite transducers have been developed with optimized composite components that have improved thermal stability and mechanical quality factors, making them promising candidates for high temperature, high power transducer applications, such as therapeutic ultrasound, high power ultrasonic wirebonding, high temperature non-destructive testing, and downhole energy harvesting. This paper will present recent developments of piezoelectric composite technology for high temperature and high power applications. The concerns and limitations of using piezoelectric composites will also be discussed, and the expected future research directions will be outlined.

  10. Structured Piezoelectric Composites: Materials and Applications

    NARCIS (Netherlands)

    Van den Ende, D.A.

    2012-01-01

    The piezoelectric effect, which causes a material to generate a voltage when it deforms, is very suitable for making integrated sensors, and (micro-) generators. However, conventional piezoelectric materials are either brittle ceramics or certain polymers with a low thermal stability, which limits t

  11. Design of a piezoelectric rotation actuator

    NARCIS (Netherlands)

    Holterman, J.; de Vries, Theodorus J.A.; Babakhani, B.; Brouwer, Dannis Michel

    2012-01-01

    In order to facilitate active damping within a linear motion system, a self-sensing piezoelectric rotation actuator has been designed. The rotation actuator consists of two piezoelectric stacks that function as linear actuators, embedded in a mechanical interface with several elastic elements, thus

  12. Influence of Particle Size of Deproteinized Bovine Bone Mineral on New Bone Formation and Implant Stability after Simultaneous Sinus Floor Elevation

    DEFF Research Database (Denmark)

    Jensen, Simon S; Aaboe, Merete; Janner, Simone F M;

    2013-01-01

    Deproteinized bovine bone mineral (DBBM) is one of the best-documented bone substitute materials for sinus floor elevation (SFE).......Deproteinized bovine bone mineral (DBBM) is one of the best-documented bone substitute materials for sinus floor elevation (SFE)....

  13. Multistage Force Amplification of Piezoelectric Stacks

    Science.gov (United States)

    Xu, Tian-Bing (Inventor); Siochi, Emilie J. (Inventor); Zuo, Lei (Inventor); Jiang, Xiaoning (Inventor); Kang, Jin Ho (Inventor)

    2015-01-01

    Embodiments of the disclosure include an apparatus and methods for using a piezoelectric device, that includes an outer flextensional casing, a first cell and a last cell serially coupled to each other and coupled to the outer flextensional casing such that each cell having a flextensional cell structure and each cell receives an input force and provides an output force that is amplified based on the input force. The apparatus further includes a piezoelectric stack coupled to each cell such that the piezoelectric stack of each cell provides piezoelectric energy based on the output force for each cell. Further, the last cell receives an input force that is the output force from the first cell and the last cell provides an output apparatus force In addition, the piezoelectric energy harvested is based on the output apparatus force. Moreover, the apparatus provides displacement based on the output apparatus force.

  14. COMBINED DAMAGE FRACTURE CRITERIA FOR PIEZOELECTRIC CERAMICS

    Institute of Scientific and Technical Information of China (English)

    Yang Xinhua; Chen Chuanyao; Hu Yuantai; Wang Cheng

    2005-01-01

    Mechanical and electrical damages are introduced to study the fracture mechanics of piezoelectric ceramics in this paper. Two kinds of piezoelectric fracture criteria are established using the method of least squares combined with a damage analysis of the well-known piezoelectric fracture experiments of Park and Sun's. One is based on a linear combination of the mechanical and electrical damages and the other on their nonlinear combination. When the combined damage D is up to its critical value Dc, piezoelectric fracture occurs. It is found from the qualitative comparison of the numerical results with the experimental data that the nonlinearly combined damage fracture criterion can give a better prediction of piezoelectric fracture. And it is concluded from the nonlinearly combined damage fracture criterion that a negative electric field impedes fracture whereas the effect of a positive electric field on fracture depends on its magnitude.

  15. Giant piezoelectricity on Si for hyperactive MEMS.

    Science.gov (United States)

    Baek, S H; Park, J; Kim, D M; Aksyuk, V A; Das, R R; Bu, S D; Felker, D A; Lettieri, J; Vaithyanathan, V; Bharadwaja, S S N; Bassiri-Gharb, N; Chen, Y B; Sun, H P; Folkman, C M; Jang, H W; Kreft, D J; Streiffer, S K; Ramesh, R; Pan, X Q; Trolier-McKinstry, S; Schlom, D G; Rzchowski, M S; Blick, R H; Eom, C B

    2011-11-18

    Microelectromechanical systems (MEMS) incorporating active piezoelectric layers offer integrated actuation, sensing, and transduction. The broad implementation of such active MEMS has long been constrained by the inability to integrate materials with giant piezoelectric response, such as Pb(Mg(1/3)Nb(2/3))O(3)-PbTiO(3) (PMN-PT). We synthesized high-quality PMN-PT epitaxial thin films on vicinal (001) Si wafers with the use of an epitaxial (001) SrTiO(3) template layer with superior piezoelectric coefficients (e(31,f) = -27 ± 3 coulombs per square meter) and figures of merit for piezoelectric energy-harvesting systems. We have incorporated these heterostructures into microcantilevers that are actuated with extremely low drive voltage due to thin-film piezoelectric properties that rival bulk PMN-PT single crystals. These epitaxial heterostructures exhibit very large electromechanical coupling for ultrasound medical imaging, microfluidic control, mechanical sensing, and energy harvesting.

  16. Analytical Optimization of Piezoelectric Circular Diaphragm Generator

    Directory of Open Access Journals (Sweden)

    S. Mohammadi

    2013-01-01

    Full Text Available This paper presents an analytical study of the piezoelectric circular diaphragm microgenerator using strain energy method. Piezoelectrics are the intelligent materials that can be used as transducer to convert mechanical energy into electrical energy and vice versa. The aim of this paper is to optimize produced electrical energy from mechanical pressure. Therefore, the circular metal plate equipped with piezoelectric circular patch has been considered with simply and clamped supports. A comprehensive modeling, parametrical study and the effect of the boundary conditions on the performance of the microgenerator have been investigated. The system is under variable pressure from an oscillating pressure source. Results are presented for PZT and PMN-PT piezoelectric materials with steel and aluminum substrates. An optimal value for the radius and thickness of the piezoelectric layer with a special support condition has been obtained.

  17. Applications of piezoelectric materials in oilfield services.

    Science.gov (United States)

    Goujon, Nicolas; Hori, Hiroshi; Liang, Kenneth K; Sinha, Bikash K

    2012-09-01

    Piezoelectric materials are used in many applications in the oilfield services industry. Four illustrative examples are given in this paper: marine seismic survey, precision pressure measurement, sonic logging-while-drilling, and ultrasonic bore-hole imaging. In marine seismics, piezoelectric hydrophones are deployed on a massive scale in a relatively benign environment. Hence, unit cost and device reliability are major considerations. The remaining three applications take place downhole in a characteristically harsh environment with high temperature and high pressure among other factors. The number of piezoelectric devices involved is generally small but otherwise highly valued. The selection of piezoelectric materials is limited, and the devices have to be engineered to withstand the operating conditions. With the global demand for energy increasing in the foreseeable future, the search for hydrocarbon resources is reaching into deeper and hotter wells. There is, therefore, a continuing and pressing need for high-temperature and high-coupling piezoelectric materials.

  18. Polymeric Piezoelectric Transducers for Hydrophone Applications

    Directory of Open Access Journals (Sweden)

    D. K. Kharat

    2007-01-01

    Full Text Available Conventional ceramic piezoelectric materials have been used in hydrophones for sonarapplications since 1940's. In the last few years since the discovery of polymeric piezoelectrichydrophones, the technology has matured, applications have emerged in extraordinary number ofcases such as underwater navigation, biomedical applications, biomimetics, etc. Hydrophones areused underwater at high hydrostatic pressures. In the presence of hydrostatic pressures, theanisotropic piezoelectric response of ceramic materials is such that it has poor hydrophone performancecharacteristics whereas polymeric piezoelectric materials show enough hydrostatic piezoelectriccoefficients. Moreover, piezoelectric polymers have low acoustic impedance, which is only 2-6 timethat of water, whereas in piezoelectric ceramics, it is typically 11-time greater than that of water. Aclose impedance match permits efficient transduction of acoustic signals in water and tissues. Newlydeveloped hydrostatic-mode polyvinylidene flouride (PVDF hydrophones use a pressure-releasesystem to achieve improved sensitivity. Recently, voided PVDF materials have been used for makinghydrophones having higher sensitivity and figure of merit than unvoided PVDF materials.

  19. Orthotropic Piezoelectricity in 2D Nanocellulose

    Science.gov (United States)

    García, Y.; Ruiz-Blanco, Yasser B.; Marrero-Ponce, Yovani; Sotomayor-Torres, C. M.

    2016-10-01

    The control of electromechanical responses within bonding regions is essential to face frontier challenges in nanotechnologies, such as molecular electronics and biotechnology. Here, we present Iβ-nanocellulose as a potentially new orthotropic 2D piezoelectric crystal. The predicted in-layer piezoelectricity is originated on a sui-generis hydrogen bonds pattern. Upon this fact and by using a combination of ab-initio and ad-hoc models, we introduce a description of electrical profiles along chemical bonds. Such developments lead to obtain a rationale for modelling the extended piezoelectric effect originated within bond scales. The order of magnitude estimated for the 2D Iβ-nanocellulose piezoelectric response, ~pm V‑1, ranks this material at the level of currently used piezoelectric energy generators and new artificial 2D designs. Such finding would be crucial for developing alternative materials to drive emerging nanotechnologies.

  20. Simple, heart-smart substitutions

    Science.gov (United States)

    Coronary artery disease - heart smart substitutions; Atherosclerosis - heart smart substitutions; Cholesterol - heart smart substitutions; Coronary heart disease - heart smart substitutions; Healthy diet - heart ...

  1. Piezoelectric accelerometers with integral electronics

    CERN Document Server

    Levinzon, Felix

    2014-01-01

    This book provides an invaluable reference to Piezoelectric Accelerometers with Integral Electronics (IEPE). It describes the design and performance parameters of IEPE accelerometers and their key elements, PE transducers and FET-input amplifiers. Coverage includes recently designed, low-noise and high temperature IEPE accelerometers. Readers will benefit from the detailed noise analysis of the IEPE accelerometer, which enables estimation of its noise floor and noise limits. Other topics useful for designers of low-noise, high temperature silicon-based electronics include noise analysis of FET

  2. Using Diffusion Bonding in Making Piezoelectric Actuators

    Science.gov (United States)

    Sager, Frank E.

    2003-01-01

    A technique for the fabrication of piezoelectric actuators that generate acceptably large forces and deflections at relatively low applied voltages involves the stacking and diffusion bonding of multiple thin piezoelectric layers coated with film electrodes. The present technique stands in contrast to an older technique in which the layers are bonded chemically, by use of urethane or epoxy agents. The older chemical-bonding technique entails several disadvantages, including the following: It is difficult to apply the bonding agents to the piezoelectric layers. It is difficult to position the layers accurately and without making mistakes. There is a problem of disposal of hazardous urethane and epoxy wastes. The urethane and epoxy agents are nonpiezoelectric materials. As such, they contribute to the thickness of a piezoelectric laminate without contributing to its performance; conversely, for a given total thickness, the performance of the laminate is below that of a unitary piezoelectric plate of the same thickness. The figure depicts some aspects of the fabrication of a laminated piezoelectric actuator by the present diffusion- bonding technique. First, stock sheets of the piezoelectric material are inspected and tested. Next, the hole pattern shown in the figure is punched into the sheets. Alternatively, if the piezoelectric material is not a polymer, then the holes are punched in thermoplastic films. Then both faces of each punched piezoelectric sheet or thermoplastic film are coated with a silver-ink electrode material by use of a silkscreen printer. The electrode and hole patterns are designed for minimal complexity and minimal waste of material. After a final electrical test, all the coated piezoelectric layers (or piezoelectric layers and coated thermoplastic films) are stacked in an alignment jig, which, in turn, is placed in a curved press for the diffusion-bonding process. In this process, the stack is pressed and heated at a specified curing temperature

  3. Piezoelectric single crystals for ultrasonic transducers in biomedical applications

    OpenAIRE

    Zhou, Qifa; Lam, Kwok Ho; Zheng, Hairong; Qiu, Weibao; Shung, K. Kirk

    2014-01-01

    Piezoelectric single crystals, which have excellent piezoelectric properties, have extensively been employed for various sensors and actuators applications. In this paper, the state–of–art in piezoelectric single crystals for ultrasonic transducer applications is reviewed. Firstly, the basic principles and design considerations of piezoelectric ultrasonic transducers will be addressed. Then, the popular piezoelectric single crystals used for ultrasonic transducer applications, including LiNbO...

  4. Piezoelectric materials and devices applications in engineering and medical sciences

    CERN Document Server

    Vijaya, M S

    2012-01-01

    Piezoelectric Materials and Devices: Applications in Engineering and Medical Sciences provides a complete overview of piezoelectric materials, covering all aspects of the materials starting from fundamental concepts. The treatment includes physics of piezoelectric materials, their characteristics and applications. The author uses simple language to explain the theory of piezoelectricity and introduce readers to the properties and design of different types of piezoelectric materials, such as those used in engineering and medical device applications.This book: Introduces various types of dielect

  5. A continuum damage model for piezoelectric materials

    Institute of Scientific and Technical Information of China (English)

    Yiming Fu; Xianqiao Wang

    2008-01-01

    In this paper, a constitutive model is proposed for piezoelectric material solids containing distributed cracks.The model is formulated in a framework of continuum damage mechanics using second rank tensors as internal variables. The Helmhotlz free energy of piezoelectric mate-rials with damage is then expressed as a polynomial including the transformed strains, the electric field vector and the ten-sorial damage variables by using the integrity bases restricted by the initial orthotropic symmetry of the material. By using the Talreja's tensor valued internal state damage variables as well as the Helmhotlz free energy of the piezoelectric mate-rial, the constitutive relations of piezoelectric materials with damage are derived. The model is applied to a special case of piezoelectric plate with transverse matrix cracks. With theKirchhoff hypothesis of plate, the free vibration equationsof the piezoelectric rectangular plate considering damage isestablished. By using Galerkin method, the equations are sol-ved. Numerical results show the effect of the damage on the free vibration of the piezoelectric plate under the close-circuit condition, and the present results are compared with those of the three-dimensional theory.

  6. Piezoelectric paint sensor for ultrasonic NDE

    Science.gov (United States)

    Li, X.; Zhang, Y.

    2007-04-01

    This paper deals with a distributed acoustic emission sensing method, which is especially suitable for piezoelectric paint. Piezoelectric paint is a composite piezoelectric material that is comprised of tiny piezoelectric particles randomly dispersed within a polymer matrix phase. An overview of the distributed acoustic emission sensing method for defect monitoring is given in this paper. The use of piezoelectric materials for ultrasonic signal measurements is next discussed along with a series of ultrasonic tests performed to verify the ultrasonic sensing capability of piezoelectric paint. To examine the mechanism of the distributed acoustic emission sensing method for crack initiation detection, the results of a finite element simulation based study is presented in this paper. The finite element model used in the parametric study is calibrated with experimental data. The effect of sensor numbers included in the array has been studied using both simulation and experimental data. Based on the preliminary results of this study, piezoelectric paint sensor appears to hold a potential for use in on-line monitoring of cracks such as those caused by fatigue in metal structures although more work is still needed before successful practical application can be made.

  7. Derivation of Piezoelectric Losses from Admittance Spectra

    Science.gov (United States)

    Zhuang, Yuan; Ural, Seyit O.; Rajapurkar, Aditya; Tuncdemir, Safakcan; Amin, Ahmed; Uchino, Kenji

    2009-04-01

    High power density piezoelectrics are required to miniaturize devices such as ultrasonic motors, transformers, and sound projectors. The power density is limited by the heat generation in piezoelectrics, therefore, clarification of the loss mechanisms is necessary. This paper provides a methodology to determine the electromechanical losses, i.e., dielectric, elastic and piezoelectric loss factors in piezoelectrics by means of a detailed analysis of the admittance/impedance spectra. This method was applied to determine the piezoelectric losses for lead zirconate titanate ceramics and lead magnesium niobate-lead titanate single crystals. The analytical solution provides a new method for obtaining the piezoelectric loss factor, which is usually neglected in practice by transducer designers. Finite element simulation demonstrated the importance of piezoelectric losses to yield a more accurate fitting to the experimental data. A phenomenological model based on two phase-shifts and the Devonshire theory of a polarizable-deformable insulator is developed to interpret the experimentally observed magnitudes of the mechanical quality factor at resonance and anti-resonance.

  8. Bone Biopsy

    Science.gov (United States)

    ... News Physician Resources Professions Site Index A-Z Bone Biopsy Bone biopsy uses a needle and imaging ... the limitations of Bone Biopsy? What is a Bone Biopsy? A bone biopsy is an image-guided ...

  9. Gradient scaling phenomenon of piezoelectricity in non-piezoelectric polyvinylidene fluoride films

    OpenAIRE

    Baskaran, Sivapalan; He, Xiangtong; Fu, John Y.

    2011-01-01

    It has been well known that flexoelectricity can be exploited to generate an analogous piezoelectric response in non-piezoelectric materials. For the direct flexoelectric effect, the induced electric polarization is linearly proportional to the applied strain gradient. Therefore, it is logical to expect that such a piezoelectric response would be enhanced in the materials with reduced dimensions. In this paper, we will report our experimental observation of such a gradient scaling phenomenon ...

  10. Miniature Piezoelectric Macro-Mass Balance

    Science.gov (United States)

    Sherrit, Stewart; Trebi-Ollennu, Ashitey; Bonitz, Robert G.; Bar-Cohen, Yoseph

    2010-01-01

    Mass balances usually use a strain gauge that requires an impedance measurement and is susceptible to noise and thermal drift. A piezoelectric balance can be used to measure mass directly by monitoring the voltage developed across the piezoelectric balance, which is linear with weight or it can be used in resonance to produce a frequency change proportional to the mass change (see figure). The piezoelectric actuator/balance is swept in frequency through its fundamental resonance. If a small mass is added to the balance, the resonance frequency shifts down in proportion to the mass. By monitoring the frequency shift, the mass can be determined. This design allows for two independent measurements of mass. Additionally, more than one sample can be verified because this invention allows for each sample to be transported away from the measuring device upon completion of the measurement, if required. A piezoelectric actuator, or many piezoelectric actuators, was placed between the collection plate of the sampling system and the support structure. As the sample mass is added to the plate, the piezoelectrics are stressed, causing them to produce a voltage that is proportional to the mass and acceleration. In addition, a change in mass delta m produces a change in the resonance frequency with delta f proportional to delta m. In a microgravity environment, the spacecraft could be accelerated to produce a force on the piezoelectric actuator that would produce a voltage proportional to the mass and acceleration. Alternatively, the acceleration could be used to force the mass on the plate, and the inertial effects of the mass on the plate would produce a shift in the resonance frequency with the change in frequency related to the mass change. Three prototypes of the mass balance mechanism were developed. These macro-mass balances each consist of a solid base and an APA 60 Cedrat flextensional piezoelectric actuator supporting a measuring plate. A similar structure with 3 APA

  11. Asymptotic curved interface models in piezoelectric composites

    Science.gov (United States)

    Serpilli, Michele

    2016-10-01

    We study the electromechanical behavior of a thin interphase, constituted by a piezoelectric anisotropic shell-like thin layer, embedded between two generic three-dimensional piezoelectric bodies by means of the asymptotic analysis in a general curvilinear framework. After defining a small real dimensionless parameter ε, which will tend to zero, we characterize two different limit models and their associated limit problems, the so-called weak and strong piezoelectric curved interface models, respectively. Moreover, we identify the non-classical electromechanical transmission conditions at the interface between the two three-dimensional bodies.

  12. The nonlinear piezoelectric tuned vibration absorber

    Science.gov (United States)

    Soltani, P.; Kerschen, G.

    2015-07-01

    This paper proposes a piezoelectric vibration absorber, termed the nonlinear piezoelectric tuned vibration absorber (NPTVA), for the mitigation of nonlinear resonances of mechanical systems. The new feature of the NPTVA is that its nonlinear restoring force is designed according to a principle of similarity, i.e., the NPTVA should be an electrical analog of the nonlinear host system. Analytical formulas for the NPTVA parameters are derived using the homotopy perturbation method. Doing so, a nonlinear generalization of Den Hartog’s equal-peak tuning rule is developed for piezoelectric vibration absorbers.

  13. Analysis of Asymmetric Piezoelectric Composite Beam

    CERN Document Server

    Chen, J -S; Wu, K -C

    2008-01-01

    This paper deals with the vibration analysis of an asymmetric composite beam composed of glass a piezoelectric material. The Bernoulli's beam theory is adopted for mechanical deformations, and the electric potential field of the piezoelectric material is assumed such that the divergence-free requirement of the electrical displacements is satisfied. The accuracy of the analytic model is assessed by comparing the resonance frequencies obtained by the analytic model with those obtained by the finite element method. The model developed can be used as a tool for designing piezoelectric actuators such as micro-pumps.

  14. Piezoelectric Voltage Coupled Reentrant Cavity Resonator

    CERN Document Server

    Carvalho, Natalia C; Floch, Jean-Michel Le; Tobar, Michael Edmund

    2014-01-01

    A piezoelectric voltage coupled microwave reentrant cavity has been developed. The central cavity post is bonded to a piezoelectric actuator allowing the voltage control of small post displacements over a high dynamic range. We show that such a cavity can be implemented as a voltage tunable resonator, a transducer for exciting and measuring mechanical modes of the structure and a transducer for measuring comparative sensitivity of the piezoelectric material. Experiments were conducted at room and cryogenic temperatures with results verified using Finite Element software.

  15. Functionally graded piezoelectric cantilever beam under load

    Energy Technology Data Exchange (ETDEWEB)

    Shi, Z.F.; Chen, Y. [Beijing Jiaotong University, School of Civil Engineering, Beijing (China)

    2004-12-01

    In the present paper, the problem of a functionally graded piezoelectric cantilever beam subjected to different loadings is studied. The piezoelectric beam is characterized by continuously graded properties for one elastic parameter and the material density. A pair of stress and induction functions in the form of polynomials is proposed and determined. Based on these functions, a set of analytical solutions for the beam subjected to different loadings is obtained. As particular cases, series of solutions for some canonical problems can be directly obtained from the solutions of the present paper, such as for the problems of a piezoelectric cantilever beam with constant body force or without body forces, etc. (orig.)

  16. Electronically droplet energy harvesting using piezoelectric cantilevers

    KAUST Repository

    Al Ahmad, Mahmoud Al

    2012-01-01

    A report is presented on free falling droplet energy harvesting using piezoelectric cantilevers. The harvester incorporates a multimorph clamped-free cantilever which is composed of five layers of lead zirconate titanate piezoelectric thick films. During the impact, the droplet kinetic energy is transferred into the form of mechanical stress forcing the piezoelectric structure to vibrate. Experimental results show energy of 0.3 μJ per droplet. The scenario of moderate falling drop intensity, i.e. 230 drops per second, yields a total energy of 400 μJ. © 2012 The Institution of Engineering and Technology.

  17. Bone Densitometry (Bone Density Scan)

    Science.gov (United States)

    ... News Physician Resources Professions Site Index A-Z Bone Densitometry (DEXA) Bone densitometry, also called dual-energy ... limitations of DEXA Bone Densitometry? What is a Bone Density Scan (DEXA)? Bone density scanning, also called ...

  18. Piezoelectric and Semiconducting Coupled Nanogenerators

    Science.gov (United States)

    Wang, Zhong L. (Inventor); Song, Jinhui (Inventor); Wang, Xudong (Inventor)

    2012-01-01

    An electrical generator includes a substrate, a semiconductor piezoelectric structure having a first end and an opposite second end disposed adjacent to the substrate, a first conductive contact and a second conductive contact. The structure bends when a force is applied adjacent to the first end, thereby causing an electrical potential difference to exist between a first side and a second side of the structure. The first conductive contact is in electrical communication with the first end and includes a material that creates a Schottky barrier between a portion of the first end of the structure and the first conductive contact. The first conductive contact is also disposed relative to the structure in a position so that the Schottky barrier is forward biased when the structure is deformed, thereby allowing current to flow from the first conductive contact into the first end.

  19. Piezoelectric nanoparticle-polymer composite foams.

    Science.gov (United States)

    McCall, William R; Kim, Kanguk; Heath, Cory; La Pierre, Gina; Sirbuly, Donald J

    2014-11-26

    Piezoelectric polymer composite foams are synthesized using different sugar-templating strategies. By incorporating sugar grains directly into polydimethylsiloxane mixtures containing barium titanate nanoparticles and carbon nanotubes, followed by removal of the sugar after polymer curing, highly compliant materials with excellent piezoelectric properties can be fabricated. Porosities and elasticity are tuned by simply adjusting the sugar/polymer mass ratio which gave an upper bound on the porosity of 73% and a lower bound on the elastic coefficient of 32 kPa. The electrical performance of the foams showed a direct relationship between porosity and the piezoelectric outputs, giving piezoelectric coefficient values of ∼112 pC/N and a power output of ∼18 mW/cm3 under a load of 10 N for the highest porosity samples. These novel materials should find exciting use in a variety of applications including energy scavenging platforms, biosensors, and acoustic actuators.

  20. Piezoelectric RL shunt damping of flexible structures

    DEFF Research Database (Denmark)

    Høgsberg, Jan Becker; Krenk, Steen

    2015-01-01

    Resonant RL shunt circuits represent a robust and effective approach to piezoelectric damping, provided that the individual shunt circuit components are calibrated accurately with respect to the dynamic properties of the corresponding flexible structure. The balanced calibration procedure applied...

  1. Guided wave propagation in multilayered piezoelectric structures

    Institute of Scientific and Technical Information of China (English)

    2009-01-01

    A general formulation of the method of the reverberation-ray matrix (MRRM) based on the state space formalism and plane wave expansion technique is presented for the analysis of guided waves in multilayered piezoelectric structures. Each layer of the structure is made of an arbitrarily anisotropic piezoelectric material. Since the state equation of each layer is derived from the three-dimensional theory of linear piezoelectricity, all wave modes are included in the formulation. Within the framework of the MRRM, the phase relation is properly established by excluding exponentially growing functions, while the scattering relation is also appropriately set up by avoiding matrix inversion operation. Consequently, the present MRRM is unconditionally numerically stable and free from computational limitations to the total number of layers, the thickness of individual layers, and the frequency range. Numerical examples are given to illustrate the good performance of the proposed formulation for the analysis of the dispersion characteristic of waves in layered piezoelectric structures.

  2. Piezoelectric devices for generating low power

    Science.gov (United States)

    Chilibon, Irinela

    2016-12-01

    This paper reviews concepts and applications in low-power electronics and energy harvesting technologies. Various piezoelectric materials and devices for small power generators useful in renewable electricity are presented. The vibrating piezoelectric device differs from the typical electrical power source in that it has capacitive rather than inductive source impedance, and may be driven by mechanical vibrations of varying amplitude. In general, vibration energy could be converted into electrical energy using one of three techniques: electrostatic charge, magnetic fields and piezoelectric. A low power piezoelectric generator, having a PZT element was realised in order to supply small electronic elements, such as optoelectronic small devices, LEDs, electronic watches, small sensors, interferometry with lasers or Micro-electro-mechanical System (MEMS) array with multi-cantilevers.

  3. Development of Vibrating Disc Piezoelectric Gyroscope

    Directory of Open Access Journals (Sweden)

    A.K. Singh

    2004-07-01

    Full Text Available The paper presents an indigenously developed vibrating disc piezoelectric gyroscope, in which both excitation and detection have been done through piezoelectric, using PZT-5H material. The gyroscope has been driven to resonant state by direct piezoelectric effect, using 20 V ac signal at 93 kHz, and the output has been detected by the reverse piezoelectric effect.The performance of this gyroscope has been tested with 3 microprocessor-controlled turntable, and the output of the gyroscope has been found" to be linearly proportional to the rotationspeed within a range ± 150 °/s. The sensitivity of the gyroscope is about 0.5 mV/°/s, which is comparable to that of other gyroscopes of similar category

  4. High Reliability Cryogenic Piezoelectric Valve Actuator Project

    Data.gov (United States)

    National Aeronautics and Space Administration — Piezoelectric actuators constructed with the "smart material" PZT offer many potential advantages for use in NASA cryo-valve missions relative to conventional...

  5. A nanoscale piezoelectric transformer for low-voltage transistors.

    Science.gov (United States)

    Agarwal, Sapan; Yablonovitch, Eli

    2014-11-12

    A novel piezoelectric voltage transformer for low-voltage transistors is proposed. Placing a piezoelectric transformer on the gate of a field-effect transistor results in the piezoelectric transformer field-effect transistor that can switch at significantly lower voltages than a conventional transistor. The piezoelectric transformer operates by using one piezoelectric to squeeze another piezoelectric to generate a higher output voltage than the input voltage. Multiple piezoelectrics can be used to squeeze a single piezoelectric layer to generate an even higher voltage amplification. Coupled electrical and mechanical modeling in COMSOL predicts a 12.5× voltage amplification for a six-layer piezoelectric transformer. This would lead to more than a 150× reduction in the power needed for communications.

  6. Piezoelectric technology in otolaryngology, and head and neck surgery: a review.

    Science.gov (United States)

    Meller, C; Havas, T E

    2017-07-01

    Piezoelectric technology has existed for many years as a surgical tool for precise removal of soft tissue and bone. The existing literature regarding its use specifically for otolaryngology, and head and neck surgery was reviewed. The databases Medline, the Cochrane Central Register of Controlled Trials, PubMed, Embase and Cambridge Scientific Abstracts were searched. Studies were selected and reviewed based on relevance. Sixty studies were identified and examined for evidence of benefits and disadvantages of piezoelectric surgery and its application in otolaryngology. The technique was compared with traditional surgical methods, in terms of intra-operative bleeding, histology, learning curve, operative time and post-operative pain. Piezoelectric technology has been successfully employed, particularly in otology and skull base surgery, where its specific advantages versus traditional drills include a lack of 'blunting' and tissue selectivity. Technical advantages include ease of use, a short learning curve and improved visibility. Its higher cost warrants consideration given that clinically significant improvements in operative time and morbidity have not yet been proven. Further studies may define the evolving role of piezoelectric surgery in otolaryngology, and head and neck surgery.

  7. Highly stretchable piezoelectric-pyroelectric hybrid nanogenerator.

    Science.gov (United States)

    Lee, Ju-Hyuck; Lee, Keun Young; Gupta, Manoj Kumar; Kim, Tae Yun; Lee, Dae-Yeong; Oh, Junho; Ryu, Changkook; Yoo, Won Jong; Kang, Chong-Yun; Yoon, Seok-Jin; Yoo, Ji-Beom; Kim, Sang-Woo

    2014-02-01

    A highly stretchable hybrid nanogenerator has been developed using a micro-patterned piezoelectric polymer P(VDF-TrFE), PDMS-CNT composite, and graphene nanosheets. Mechanical and thermal energies are simultaneously harvested from a single cell of the device. The hybrid nanogenerator exhibits high robustness behavior even after 30% stretching and generates very stable piezoelectric and pyroelectric power outputs due to micro-pattern designing. © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  8. Gap Waves in Piezoelectric layered Medium

    Directory of Open Access Journals (Sweden)

    Danoyan Z.N.

    2007-03-01

    Full Text Available In the present paper the conditions of existence of shear electroelastic gap waves in piezoelectric-vacuum-dielectric layered system are found. It is shown that in the discontact layered system the gap electroelastic waves can be propagated. It is considered the limiting case when the thickness of vacuuming layer tends to zero. It is proved that the statement of the problem is true when there is no acoustic contact between piezoelectric and dielectric grounded media.

  9. In situ health monitoring of piezoelectric sensors

    Science.gov (United States)

    Jensen, Scott L. (Inventor); Drouant, George J. (Inventor)

    2013-01-01

    An in situ health monitoring apparatus may include an exciter circuit that applies a pulse to a piezoelectric transducer and a data processing system that determines the piezoelectric transducer's dynamic response to the first pulse. The dynamic response can be used to evaluate the operating range, health, and as-mounted resonance frequency of the transducer, as well as the strength of a coupling between the transducer and a structure and the health of the structure.

  10. Analysis of piezoelectric structures and devices

    CERN Document Server

    Chen, Weiqiu; Wang, Ji

    2013-01-01

    This edited work covers piezoelectric materials in the form of beams, plates, shells, and other structural components in modern devices and structures. Applications are frequency control and detection functions in resonators, sensors, actuators, oscillations, and other smart and intelligent structures. The contributions cover novel methods for the analysis of piezoelectric structures including wave propagation, high frequency vibration, material characterization, and optimization of structures. Understanding of these methods is increasingly important in the design and modelling of next generat

  11. Piezosurgical osteotomy for harvesting intraoral block bone graft

    Directory of Open Access Journals (Sweden)

    Mahalingam Lakshmiganthan

    2012-01-01

    Full Text Available The use of ultrasonic vibrations for the cutting of bone was first introduced two decades ago. Piezoelectric surgery is a minimally invasive technique that lessens the risk of damage to surrounding soft tissues and important structures such as nerves, vessels, and mucosa. It also reduces damage to osteocytes and permits good survival of bony cells during harvesting of bone. Grafting with intraoral bone blocks is a good way to reconstruct severe horizontal and vertical bone resorption in future implants sites. The piezosurgery system creates an effective osteotomy with minimal or no trauma to soft tissue in contrast to conventional surgical burs or saws and minimizes a patient′s psychological stress and fear during osteotomy under local anesthesia. The purpose of this article is to describe the harvesting of intraoral bone blocks using the piezoelectric surgery device.

  12. Lead-free piezoelectrics: V(3+) to V(5+) ion conversion promoting the performances of V-doped Zinc Oxide.

    Science.gov (United States)

    Laurenti, M; Castellino, M; Perrone, D; Asvarov, A; Canavese, G; Chiolerio, A

    2017-02-06

    Vanadium doped ZnO (VZO) thin films were grown by RF magnetron sputtering, starting from a ZnO:V ceramic target. The crystal structure, chemical composition, electric and piezoelectric properties of the films were investigated either on the as-grown thin films or after a post-deposition rapid thermal annealing (RTA) treatment performed at 600 °C for different lengths of time (1 and 5 min) in an oxygen atmosphere. Substitutional doping of Zn(2+) with V(3+) and V(5+) ions strongly deteriorated the hexagonal wurtzite ZnO structure of the as-grown thin films due to lattice distortion. The resulting slight amorphization led to a poor piezoelectric response and higher resistivity. After the RTA treatment, strong c-axis oriented VZO thin films were obtained, together with a partial conversion of the starting V(3+) ions into V(5+). The improvement of the crystal structure and the stronger polarity of both V(3+) - O and V(5+) - O chemical bonds, together with the corresponding easier rotation under the application of an external electric field, positively affected the piezoelectric response and increased conductivity. This was confirmed by closed-loop butterfly piezoelectric curves, by a maximum d33 piezoelectric coefficient of 85 pm·V(-1), and also by ferroelectric switching domains with a well-defined polarization hysteresis curve, featuring a residual polarization of 12.5 μC∙cm(-2).

  13. Lead-free piezoelectrics: V3+ to V5+ ion conversion promoting the performances of V-doped Zinc Oxide

    Science.gov (United States)

    Laurenti, M.; Castellino, M.; Perrone, D.; Asvarov, A.; Canavese, G.; Chiolerio, A.

    2017-01-01

    Vanadium doped ZnO (VZO) thin films were grown by RF magnetron sputtering, starting from a ZnO:V ceramic target. The crystal structure, chemical composition, electric and piezoelectric properties of the films were investigated either on the as-grown thin films or after a post-deposition rapid thermal annealing (RTA) treatment performed at 600 °C for different lengths of time (1 and 5 min) in an oxygen atmosphere. Substitutional doping of Zn2+ with V3+ and V5+ ions strongly deteriorated the hexagonal wurtzite ZnO structure of the as-grown thin films due to lattice distortion. The resulting slight amorphization led to a poor piezoelectric response and higher resistivity. After the RTA treatment, strong c-axis oriented VZO thin films were obtained, together with a partial conversion of the starting V3+ ions into V5+. The improvement of the crystal structure and the stronger polarity of both V3+ – O and V5+ – O chemical bonds, together with the corresponding easier rotation under the application of an external electric field, positively affected the piezoelectric response and increased conductivity. This was confirmed by closed-loop butterfly piezoelectric curves, by a maximum d33 piezoelectric coefficient of 85 pm·V−1, and also by ferroelectric switching domains with a well-defined polarization hysteresis curve, featuring a residual polarization of 12.5 μC∙cm−2. PMID:28165040

  14. Transmission electron microscopy investigation of the microstructural mechanisms for the piezoelectricity in lead-free perovskite ceramics

    Energy Technology Data Exchange (ETDEWEB)

    Ma, Cheng [Iowa State Univ., Ames, IA (United States)

    2012-01-01

    Lead-free materials with superior piezoelectricity are in increasingly urgent demand in the current century, because the industrial standard Pb(Zr,Ti)O3-based piezoelectrics, which contain over 60 weight% of the toxic element lead, pose severe environmental hazards. Although significant research efforts have been devoted in the past decade, no effective lead-free substitute for Pb(Zr,Ti)O3 has been identified yet. One of the primary hindrances to the development of lead-free piezoelectrics lies in the ignorance of the microstructural mechanism for the electric-field-induced strains in the currently existing compositions. In this dissertation, the microstructural origin for the high piezoelectricity in (1-x)(Bi1/2Na1/2)TiO3-xBaTiO3 [(1-x)BNT-xBT], the most widely studied lead-free piezoelectric system, has been elucidated.

  15. Base Metal Co-Fired Multilayer Piezoelectrics

    Directory of Open Access Journals (Sweden)

    Lisheng Gao

    2016-03-01

    Full Text Available Piezoelectrics have been widely used in different kinds of applications, from the automobile industry to consumer electronics. The novel multilayer piezoelectrics, which are inspired by multilayer ceramic capacitors, not only minimize the size of the functional parts, but also maximize energy efficiency. Development of multilayer piezoelectric devices is at a significant crossroads on the way to achieving low costs, high efficiency, and excellent reliability. Concerning the costs of manufacturing multilayer piezoelectrics, the trend is to replace the costly noble metal internal electrodes with base metal materials. This paper discusses the materials development of metal co-firing and the progress of integrating current base metal chemistries. There are some significant considerations in metal co-firing multilayer piezoelectrics: retaining stoichiometry with volatile Pb and alkaline elements in ceramics, the selection of appropriate sintering agents to lower the sintering temperature with minimum impact on piezoelectric performance, and designing effective binder formulation for low pO2 burnout to prevent oxidation of Ni and Cu base metal.

  16. Dielectric loss against piezoelectric power harvesting

    Science.gov (United States)

    Liang, Junrui; Shu-Hung Chung, Henry; Liao, Wei-Hsin

    2014-09-01

    Piezoelectricity is one of the most popular electromechanical transduction mechanisms for constructing kinetic energy harvesting systems. When a standard energy harvesting (SEH) interface circuit, i.e., bridge rectifier plus filter capacitor, is utilized for collecting piezoelectric power, the previous literature showed that the power conversion can be well predicted without much consideration for the effect of dielectric loss. Yet, as the conversion power gets higher by adopting power-boosting interface circuits, such as synchronized switch harvesting on inductor (SSHI), the neglect of dielectric loss might give rise to deviation in harvested power estimation. Given the continuous progress on power-boosting interface circuits, the role of dielectric loss in practical piezoelectric energy harvesting (PEH) systems should receive attention with better evaluation. Based on the integrated equivalent impedance network model, this fast track communication provides a comprehensive study on the susceptibility of harvested power in PEH systems under different conditions. It shows that, dielectric loss always counteracts piezoelectric power harvesting by causing charge leakage across piezoelectric capacitance. In particular, taking corresponding ideal lossless cases as references, the counteractive effect might be aggravated under one of the five conditions: larger dielectric loss tangent, lower vibration frequency, further away from resonance, weaker electromechanical coupling, or using power-boosting interface circuit. These relationships are valuable for the study of PEH systems, as they not only help explain the role of dielectric loss in piezoelectric power harvesting, but also add complementary insights for material, structure, excitation, and circuit considerations towards holistic evaluation and design for practical PEH systems.

  17. Dielectrophoretically structured piezoelectric composites with high aspect ratio piezoelectric particles inclusions

    NARCIS (Netherlands)

    Ende, D.A. van den; Kempen, S.E. van; Wu, X.; Groen, W.A.; Randall, C.A.; Zwaag, S. van der

    2012-01-01

    Piezoelectric composites were prepared by dielectrophoretic alignment of high aspect ratio piezoelectric particles in a thermosetting polymer matrix. A high level of alignment was achieved in the cured composite from a resin containing randomly oriented high aspect ratio particles. Upon application

  18. Osteostatin-coated porous titanium can improve early bone regeneration of cortical bone defects in rats

    NARCIS (Netherlands)

    Van Der Stok, Johan; Lozano, Daniel; Chai, Yoke Chin; Amin Yavari, Saber; Bastidas Coral, Angela P.; Verhaar, Jan A N; Gómez-Barrena, Enrique; Schrooten, Jan; Jahr, Holger; Zadpoor, Amir A.; Esbrit, Pedro; Weinans, Harrie

    2015-01-01

    A promising bone graft substitute is porous titanium. Porous titanium, produced by selective laser melting (SLM), can be made as a completely open porous and load-bearing scaffold that facilitates bone regeneration through osteoconduction. In this study, the bone regenerative capacity of porous tita

  19. Growth and Characterization of Lead-free Piezoelectric Single Crystals

    Directory of Open Access Journals (Sweden)

    Philippe Veber

    2015-11-01

    Full Text Available Lead-free piezoelectric materials attract more and more attention owing to the environmental toxicity of lead-containing materials. In this work, we review our first attempts of single crystal grown by the top-seeded solution growth method of BaTiO3 substituted with zirconium and calcium (BCTZ and (K0.5Na0.5NbO3 substituted with lithium, tantalum, and antimony (KNLSTN. The growth methodology is optimized in order to reach the best compositions where enhanced properties are expected. Chemical analysis and electrical characterizations are presented for both kinds of crystals. The compositionally-dependent electrical performance is investigated for a better understanding of the relationship between the composition and electrical properties. A cross-over from relaxor to ferroelectric state in BCTZ solid solution is evidenced similar to the one reported in ceramics. In KNLSTN single crystals, we observed a substantial evolution of the orthorhombic-to-tetragonal phase transition under minute composition changes.

  20. Model of a Piezoelectric Transducer

    Science.gov (United States)

    Goodenow, Debra

    2004-01-01

    It's difficult to control liquid and gas in propellant tanks in zero gravity. A possible a design would utilize acoustic liquid manipulation (ALM) technology which uses ultrasonic beams conducted through a liquid and solid media, to push gas bubbles in the liquid to desirable locations. We can propel and control the bubble with acoustic radiation pressure by aiming the acoustic waves on the bubble s surface. This allows us to design a so called smart tank in which the ALM devices transfer the gas to the outer wall of the tank and isolating the liquid in the center. Because the heat transfer rate of a gas is lower of that of the liquid it would substantially decrease boil off and provide of for a longer storage life. The ALM beam is composed of little wavelets which are individual waves that constructively interfere with each other to produce a single, combined acoustic wave front. This is accomplished by using a set of synchronized ultrasound transducers arranged in an array. A slight phase offset of these elements allows us to focus and steer the beam. The device that we are using to produce the acoustic beam is called the piezoelectric transducer. This device converts electrical energy to mechanical energy, which appears in the form of acoustic energy. Therefore the behavior of the device is dependent on both the mechanical characteristics, such as its density, cross-sectional area, and its electrical characteristics, such as, electric flux permittivity and coupling factor. These devices can also be set up in a number of modes which are determined by the way the piezoelectric device is arranged, and the shape of the transducer. For this application we are using the longitudinal or thickness mode for our operation. The transducer also vibrates in the lateral mode, and one of the goals of my project is to decrease the amount of energy lost to the lateral mode. To model the behavior of the transducers I will be using Pspice, electric circuit modeling tool, to

  1. Piezoelectric microcantilever serum protein detector

    Science.gov (United States)

    Capobianco, Joseph A.

    The development of a serum protein detector will provide opportunities for better screening of at-risk cancer patients, tighter surveillance of disease recurrence and better monitoring of treatment. An integrated system that can process clinical samples for a number of different types of biomarkers would be a useful tool in the early detection of cancer. Also, screening biomarkers such as antibodies in serum would provide clinicians with information regarding the patient's response to treatment. Therefore, the goal of this study is to develop a sensor which can be used for rapid, all-electrical, real-time, label-fee, in-situ, specific quantification of cancer markers, e.g., human epidermal receptor 2 (Her2) or antibodies, in serum. To achieve this end, piezoelectric microcantilever sensors (PEMS) were constructed using an 8 mum thick lead magnesium niobate-lead titanate (PMN-PT) freestanding film as the piezoelectric layer. The desired limit of detection is on the order of pg/mL. In order to achieve this goal the higher frequency lateral extension modes were used. Also, as the driving and sensing of the PEMS is electrical, the PEMS must be insulated in a manner that allows it to function in aqueous solutions. The insulation layer must also be compatible with standardized bioconjugation techniques. Finally, detection of both cancer antigens and antibodies in serum was carried out, and the results were compared to a standard commercialized protocol. PEMS have demonstrated the capability of detecting Her2 at a concentration of 5 pg/mL in diluted human serum (1:40) in less than 1 hour. The approach can be easily translated into the clinical setting because the sensitivity is more than sufficient for monitoring prognosis of breast cancer patients. In addition to Her2 detection, antibodies in serum were assayed in order to demonstrate the feasibility of monitoring the immune response for antibody-dependent cellular cytotoxicity (ADCC) in patients on antibody therapies

  2. Bone within a bone

    Energy Technology Data Exchange (ETDEWEB)

    Williams, H.J.; Davies, A.M. E-mail: wendy.turner@roh.nhs.uk; Chapman, S

    2004-02-01

    The 'bone within a bone' appearance is a well-recognized radiological term with a variety of causes. It is important to recognize this appearance and also to be aware of the differential diagnosis. A number of common conditions infrequently cause this appearance. Other causes are rare and some remain primarily of historical interest, as they are no longer encountered in clinical practice. In this review we illustrate some of the conditions that can give the bone within a bone appearance and discuss the physiological and pathological aetiology of each where known.

  3. Analysis of nonlinear transient responses of piezoelectric resonators.

    Science.gov (United States)

    Hagiwara, Manabu; Takahashi, Seita; Hoshina, Takuya; Takeda, Hiroaki; Tsurumi, Takaaki

    2011-09-01

    The electric transient response method is an effective technique to evaluate material constants of piezoelectric ceramics under high-power driving. In this study, we tried to incorporate nonlinear piezoelectric behaviors in the analysis of transient responses. As a base for handling the nonlinear piezoelectric responses, we proposed an assumption that the electric displacement is proportional to the strain without phase lag, which could be described by a real and constant piezoelectric e-coefficient. Piezoelectric constitutive equations including nonlinear responses were proposed to calculate transient responses of a piezoelectric resonator. The envelopes and waveforms of current and vibration velocity in transient responses observed in some piezoelectric ceramics could be fitted with the calculation including nonlinear responses. The procedure for calculation of mechanical quality factor Q(m) for piezoelectric resonators with nonlinear behaviors was also proposed.

  4. Concept Developed for an Implanted Stimulated Muscle-Powered Piezoelectric Generator

    Science.gov (United States)

    Lewandowski, Beth; Kilgore, Kevin; Ercegovic, David; Gustafson, Kenneth

    2005-01-01

    Implanted electronic devices are typically powered by batteries or transcutaneous power transmission. Batteries must be replaced or recharged, and transcutaneous power sources burden the patient or subject with external equipment prone to failure. A completely self-sustaining implanted power source would alleviate these limitations. Skeletal muscle provides an available autologous power source containing native chemical energy that produces power in excess of the requirements for muscle activation by motor nerve stimulation. A concept has been developed to convert stimulated skeletal muscle power into electrical energy (see the preceding illustration). We propose to connect a piezoelectric generator between a muscle tendon and bone. Electrically stimulated muscle contractions would exert force on the piezoelectric generator, charging a storage circuit that would be used to power the stimulator and other devices.

  5. Single-Tooth Osteotomy Using Piezoelectric Devices to Treat an Ankylosed Maxillary Molar.

    Science.gov (United States)

    You, Tae Min; Kang, Joon Hyun; Kim, Kee-Deog; Park, Wonse

    2016-01-01

    Single-tooth osteotomy is a surgical technique in which the tooth and adjacent bone with sufficient soft tissue are repositioned in a single step or moved orthodontically. It is not used in the maxillary posterior region because of poor accessibility, bleeding complications, and anatomical limitations such as the maxillary sinus. However, the development of piezoelectric surgical devices and the popularization of the sinus floor elevation procedure have simplified the approach to the posterior maxillary area. This article reports two cases of single-tooth osteotomy of ankylosed teeth that were performed safely in the posterior maxilla with the use of a piezoelectric device and a sinus membrane elevation. In addition, several merits of this approach as compared with conventional osteotomy are described.

  6. Theoretical and experimental research on the influence of multiple piezoelectric effects on physical parameters of piezoelectric actuator

    Directory of Open Access Journals (Sweden)

    Liping Shi

    2015-04-01

    Full Text Available Compared with the traditional actuator of machinery and electricity, the piezoelectric actuator has the advantages of a compact structure, small volume, no mechanical friction, athermancy and no electromagnetic interference. Therefore, it has high application value in the fields of MEMS, bioengineering, medical science and so on. This article draws conclusions from the influence of multiple piezoelectric effects on the physical parameters (dielectric coefficient, equivalent capacity, energy conversion and piezoelectric coefficient of piezoelectric actuators. These data from theoretical and experimental research show the following: (1 The rate between the dielectric coefficient of piezoelectric in mechanical freedom and clamping is obtained from the secondary direct piezoelectric effect, which enhances the dielectric property, increases the dielectric coefficient and decreases the coefficient of dielectric isolation; (2 Under external field, E n ( ex = E 1 , exterior stress T = 0, that is to say, under the boundary condition of mechanical freedom, piezoelectric can store electric energy and elasticity, which obtains power density, elastic density and an electromechanical coupling factor; (3 According to the piezoelectric strain S i ( 1 , piezoelectric displacement D m ( 2 and piezoelectric strain S i ( 3 of multiple piezoelectric effects, when the dielectric coefficient of the first converse piezoelectric effect ε33 is 1326 and the dielectric coefficient of the secondary direct piezoelectric effect increases to 3336, the dielectric coefficient of the ceramic chip increases. When the piezoelectric coefficient of the first converse piezoelectric effect d33 is 595 and the piezoelectric coefficient of the secondary direct piezoelectric effect decreases to 240, the piezoelectric coefficient of the ceramic chip will decrease. It is of major significance both in the applications and in basic theory to research the influence of multiple piezoelectric

  7. Multilayer Piezoelectric Stack Actuator Characterization

    Science.gov (United States)

    Sherrit, Stewart; Jones, Christopher M.; Aldrich, Jack B.; Blodget, Chad; Bao, Xioaqi; Badescu, Mircea; Bar-Cohen, Yoseph

    2008-01-01

    Future NASA missions are increasingly seeking to use actuators for precision positioning to accuracies of the order of fractions of a nanometer. For this purpose, multilayer piezoelectric stacks are being considered as actuators for driving these precision mechanisms. In this study, sets of commercial PZT stacks were tested in various AC and DC conditions at both nominal and extreme temperatures and voltages. AC signal testing included impedance, capacitance and dielectric loss factor of each actuator as a function of the small-signal driving sinusoidal frequency, and the ambient temperature. DC signal testing includes leakage current and displacement as a function of the applied DC voltage. The applied DC voltage was increased to over eight times the manufacturers' specifications to investigate the correlation between leakage current and breakdown voltage. Resonance characterization as a function of temperature was done over a temperature range of -180C to +200C which generally exceeded the manufacturers' specifications. In order to study the lifetime performance of these stacks, five actuators from one manufacturer were driven by a 60volt, 2 kHz sine-wave for ten billion cycles. The tests were performed using a Lab-View controlled automated data acquisition system that monitored the waveform of the stack electrical current and voltage. The measurements included the displacement, impedance, capacitance and leakage current and the analysis of the experimental results will be presented.

  8. Exploration of electric properties of bone compared to cement: streaming potential and piezoelectirc properties

    Science.gov (United States)

    Dry, Carolyn

    2015-03-01

    Bone is a material after which to model construction materials for many reasons, including its great strength, toughness, and adaptability. This paper focuses on bone's intrinsic ability to adapt to its environment, namely loading conditions. Research on bone's electrical properties reveals that two phenomena occur in bone to allow it to adapt to environmental changes; they are the inherent piezoelectric property of bone and the streaming potential of bone [1]. Together they create charge differences that attract ions to specific regions of the bone, namely those under greatest stress, in order to build up the region to handle the applied load. Research on the utilization of these properties in cement in order to increase adaptability was studied along with 1) the inherent electric properties of the cement itself and 2) considered the introduction of a different polymer or ceramic within the cement to impart piezoelectricity and streaming potential.

  9. Extrusion and properties of lead zirconate titanate piezoelectric ceramics

    DEFF Research Database (Denmark)

    Cai, S.; Millar, C.E.; Pedersen, L.

    1997-01-01

    The purpose of this work was to develop a procedure for fabricating electroceramic actuators with good piezoelectric properties. The preparation of lead zirconate titanate (PZT) piezoelectric ceramic rods and tubes by extrusion processing is described. The microstructure of extrudates was investi......The purpose of this work was to develop a procedure for fabricating electroceramic actuators with good piezoelectric properties. The preparation of lead zirconate titanate (PZT) piezoelectric ceramic rods and tubes by extrusion processing is described. The microstructure of extrudates...

  10. Lead-Free Metamaterials with Enormous Apparent Piezoelectric Response.

    Science.gov (United States)

    Zhou, Wanfeng; Chen, Pan; Pan, Qi; Zhang, Xiaotong; Chu, Baojin

    2015-11-01

    Lead-free flexoelectric piezoelectric metamaterials are created by applying an asymmetric chemical reduction to Na1/2 Bi1/2 TiO3 -BaTiO3 ceramics. The reduction induces two gradient-generating mechanisms, curvature structure and chemical inhomogeneity, and enhances the flexoelectric effect. The ceramics behave like piezoelectric materials, exhibiting an enormous and high-temperature stable apparent piezoelectric response, outperforming existing lead-oxide-based piezoelectrics.

  11. Energy Harvesting From Low Frequency Applications Using Piezoelectric Materials

    Energy Technology Data Exchange (ETDEWEB)

    Li, Huidong; Tian, Chuan; Deng, Zhiqun

    2014-11-06

    This paper reviewed the state of research on piezoelectric energy harvesters. Various types of harvester configurations, piezoelectric materials, and techniques used to improve the mechanical-to-electrical energy conversion efficiency were discussed. Most of the piezoelectric energy harvesters studied today have focused on scavenging mechanical energy from vibration sources due to their abundance in both natural and industrial environments. Cantilever beams have been the most studied structure for piezoelectric energy harvester to date because of the high responsiveness to small vibrations.

  12. Self-oscillating loop based piezoelectric power converter

    OpenAIRE

    Rødgaard, Martin Schøler; Andersen, Michael A. E.; Esbern, Andreas; Meyer, Kasper Sinding

    2013-01-01

    The present invention relates to a piezoelectric power converter comprising an input driver electrically coupled directly to an input or primary electrode of the piezoelectric transformer without any intervening series or parallel inductor. A feedback loop is operatively coupled between an output voltage of the piezoelectric transformer and the input driver to provide a self-oscillation loop around a primary section of the piezoelectric transformer oscillating at an excitation frequency. Elec...

  13. Bone Grafting: Sourcing, Timing, Strategies, and Alternatives.

    Science.gov (United States)

    Egol, Kenneth A; Nauth, Aaron; Lee, Mark; Pape, Hans-Christoph; Watson, J Tracy; Borrelli, Joseph

    2015-12-01

    Acute fractures, nonunions, and nonunions with bone defects or osteomyelitis often need bone graft to facilitate union. There are several factors to consider when it is determined that a bone graft is needed. These factors include the source of the bone graft (autograft vs. allograft), proper timing for placement of the bone graft, strategies to avoid further complications (particularly in the setting of osteomyelitis), and with the development of a variety of bone graft substitutes, whether alternatives to autograft are available and appropriate for the task at hand. Autograft bone has commonly been referred to as the "gold standard" of bone grafts, against which the efficacy of other grafts has been measured. The best timing for when to place a bone graft or substitute is also somewhat controversial, particularly after an open fracture or a potentially contaminated bed. The treatment of infected nonunions, particularly those that require a graft to facilitate healing, can be quite challenging. Typically, the infection is completely eradicated before placement of a bone graft, but achieving a sterile bed and the timing of a bone graft require strategic thinking and planning. This review outlines the benefits of autografts, the most suitable sites for harvesting bone grafts, the timing of bone graft procedures, the potential risks and benefits of grafting in the face of infection, and the currently available bone graft extenders.

  14. Multilayer modal actuator-based piezoelectric transformers.

    Science.gov (United States)

    Huang, Yao-Tien; Wu, Wen-Jong; Wang, Yen-Chieh; Lee, Chih-Kung

    2007-02-01

    An innovative, multilayer piezoelectric transformer equipped with a full modal filtering input electrode is reported herein. This modal-shaped electrode, based on the orthogonal property of structural vibration modes, is characterized by full modal filtering to ensure that only the desired vibration mode is excited during operation. The newly developed piezoelectric transformer is comprised of three layers: a multilayered input layer, an insulation layer, and a single output layer. The electrode shape of the input layer is derived from its structural vibration modal shape, which takes advantage of the orthogonal property of the vibration modes to achieve a full modal filtering effect. The insulation layer possesses two functions: first, to couple the mechanical vibration energy between the input and output, and second, to provide electrical insulation between the two layers. To meet the two functions, a low temperature, co-fired ceramic (LTCC) was used to provide the high mechanical rigidity and high electrical insulation. It can be shown that this newly developed piezoelectric transformer has the advantage of possessing a more efficient energy transfer and a wider optimal working frequency range when compared to traditional piezoelectric transformers. A multilayer piezoelectric, transformer-based inverter applicable for use in LCD monitors or portable displays is presented as well.

  15. Piezoelectric Energy Harvester for Batteryless Switch Devices

    Science.gov (United States)

    Kim, Min-Soo; Lee, Sung-Chan; Kim, Sin-Woong; Jeong, Soon-Jong; Kim, In-Sung; Song, Jaesung

    2013-10-01

    This study investigated a piezoelectric energy-harvesting system for a mechanical switch device. Piezoelectric ceramics of 0.4Pb(Mg1/3Nb2/3)O3-0.25PbZrO3-0.35PbTiO3 were prepared by using a conventional solid-state reaction method. Li2O, Bi2O3, and CuO additions were used as sintering aids to develop piezoelectric ceramics for low-temperature sintering. Multilayer piezoelectric ceramics with 10×10×3 mm3 sizes and with Ag-Pd inner electrodes were manufactured by using the conventional tape-casting method with the prepared powder. A prototype of a piezoelectric batteryless switch device using the multilayer ceramics was produced. It showed an output peak-to-peak voltage of 3.8 V and an output power per strike of 18 µW. The performance of the device was good enough for practical use.

  16. Piezoelectric Actuators : Expansion from IT/Robotics to Ecological/Energy Applications(Lead-Free Piezoelectric Material and Devices)

    OpenAIRE

    Kenji, Uchino; International Center for Actuators and Transducers, The Pennsylvania State University, University Park

    2007-01-01

    Piezoelectric actuators have been commercialized in various areas such as information technology, robotics, bio-, medical engineering, ecological and energy engineering. This paper reviews their recent application developments and foresees the future of piezoelectric actuators.

  17. 40 CFR 721.8780 - Substituted pyridine azo substituted phenyl.

    Science.gov (United States)

    2010-07-01

    ... 40 Protection of Environment 30 2010-07-01 2010-07-01 false Substituted pyridine azo substituted... Specific Chemical Substances § 721.8780 Substituted pyridine azo substituted phenyl. (a) Chemical substance... substituted pyridine azo substituted phenyl (PMNs P-96-767 and P-96-773) are subject to reporting under...

  18. Low-power piezoelectric micro-machined valve

    Science.gov (United States)

    Gianchandani, Yogesh B. (Inventor); Nellis, Gregory Francis (Inventor); Klein, Sanford A. (Inventor); Park, John Moon (Inventor); Evans, Allan Thomas (Inventor); Taylor, Ryan (Inventor); Brosten, Tyler R. (Inventor)

    2010-01-01

    A piezoelectric microvalve employs a valve element formed of hermetically sealed and opposed plates flexed together by a cross axis piezoelectric element. Large flow modulation with small piezoelectric actuator displacement is obtained by perimeter augmentation of the valve seat which dramatically increases the change in valve flow area for small deflections.

  19. Characterization of a Piezoelectric Buzzer Using a Michelson Interferometer

    Science.gov (United States)

    Lloyd, S.; Paetkau, M.

    2010-01-01

    A piezoelectric material generates an electric potential across its surface when subjected to mechanical stress; conversely, the inverse piezoelectric effect describes the expansion or contraction of the material when subjected to some applied voltage. Piezoelectric materials are used in devices such as doorbell buzzers, barbeque igniters, and…

  20. Comparison of Stabilization of Piezoelectric Euler-Bernoulli Beam Models

    NARCIS (Netherlands)

    de Jong, Matthias; Scherpen, Jacquelien M.A.; Morris, Kirsten

    2016-01-01

    Piezoelectric materials are used in many control and sensing applications via a strip of piezoelectric material also known as a piezoelectric beam. Applications can be vibration control in (complex) mechanical structures and on-line measurement or compensation in high-precision technology for shape

  1. Parametric block diagrams of a multi-layer piezoelectric transducer of nano- and microdisplacements under transverse piezoelectric effect

    Science.gov (United States)

    Afonin, S. M.

    2017-01-01

    A structural-parametric model and parametric block diagrams of a piezoelectric transducer in the transverse piezoelectric effect are obtained with regard to the counter-electromotive force. The transfer functions of the multi-layer piezoelectric transducer of nano- and microdisplacements are determined with regard to the influence of geometric and physical parameters of the multi-layer piezoelectric transducer, the counter-electromotive force, and the external load.

  2. Green piezoelectric for autonomous smart textile

    Science.gov (United States)

    Lemaire, E.; Borsa, C. J.; Briand, D.

    2015-12-01

    In this work, the fabrication of Rochelle salt based piezoelectric textiles are shown. Structures composed of fibers and Rochelle salt are easily produced using green processes. Both manufacturing and the material itself are really efficient in terms of environmental impact, considering the fabrication processes and the material resources involved. Additionally Rochelle salt is biocompatible. In this green paradigm, active sensing or actuating textiles are developed. Thus processing method and piezoelectric properties have been studied: (1) pure crystals are used as acoustic actuator, (2) fabrication of the textile-based composite is detailed, (3) converse effective d33 is evaluated and compared to lead zirconate titanate ceramic. The utility of textile-based piezoelectric merits its use in a wide array of applications.

  3. Performance analysis of piezoelectric bimorph generator

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    In this paper,the theoretical model and simulation of the performance of a piezoelectric (PZT)bimorph generator is introduced.The generator consists of two piezoelectric plates bonded on a substrate metal plate.For an effective electromechanical coupling coefficient (EECC) and the generated energy,the analytical formulae are established with the thickness ratio and the Young's modulus ratio as variables.After giving correlative material parameters,the EECC and generated energy can be computed.The results show that there is a optimal thickness ratio for a piezoelectric bimorph generator to achieve the maximum EECC and electrical energy.The EECC and generated energy decrease with an increase of the Young's modulus ratio.In addition,the influence of mechanical source on electrical energy generation and power output is also considered.

  4. Ciliae-based actuator with piezoelectric excitation

    Science.gov (United States)

    Pott, Peter P.; Carrasco, Alvaro; Schlaak, Helmut F.

    2012-06-01

    Small actuators based on the inverse piezoelectric effect are successfully deployed in commercial applications. Usually, ultrasonic motors are used. Based on resonance effects these motors provide a pronounced nonlinearity at low speeds and thus put high demands on the control algorithm. In contrast, piezoelectric stepping motors are mechanically complex and provide only low speeds. The contribution at hand describes a proposed design for a new piezoelectric motor based on cilia friction that can be manufactured at low costs. The cilia are made from uniaxial carbon-fibre reinforced plastics. The derived CFRP-brushes are pressed perpendicularly to the rotor surface to produce force or torque. First experiments prove the feasibility of the concept. A net pushing force of 500 mN is achieved.

  5. Flow Energy Piezoelectric Bimorph Nozzle Harvester

    Science.gov (United States)

    Sherrit, Stewart (Inventor); Walkemeyer, Phillip E. (Inventor); Hall, Jeffrey L. (Inventor); Lee, Hyeong Jae (Inventor); Colonius, Tim (Inventor); Tosi, Phillipe (Inventor); Kim, Namhyo (Inventor); Sun, Kai (Inventor); Corbett, Thomas Gary (Inventor); Arrazola, Alvaro Jose (Inventor)

    2016-01-01

    A flow energy harvesting device having a harvester pipe includes a flow inlet that receives flow from a primary pipe, a flow outlet that returns the flow into the primary pipe, and a flow diverter within the harvester pipe having an inlet section coupled to the flow inlet, a flow constriction section coupled to the inlet section and positioned at a midpoint of the harvester pipe and having a spline shape with a substantially reduced flow opening size at a constriction point along the spline shape, and an outlet section coupled to the constriction section. The harvester pipe may further include a piezoelectric structure extending from the inlet section through the constriction section and point such that the fluid flow past the constriction point results in oscillatory pressure amplitude inducing vibrations in the piezoelectric structure sufficient to cause a direct piezoelectric effect and to generate electrical power for harvesting.

  6. Piezoelectric energy harvesting computer controlled test bench.

    Science.gov (United States)

    Vázquez-Rodriguez, M; Jiménez, F J; de Frutos, J; Alonso, D

    2016-09-01

    In this paper a new computer controlled (C.C.) laboratory test bench is presented. The patented test bench is made up of a C.C. road traffic simulator, C.C. electronic hardware involved in automating measurements, and test bench control software interface programmed in LabVIEW™. Our research is focused on characterizing electronic energy harvesting piezoelectric-based elements in road traffic environments to extract (or "harvest") maximum power. In mechanical to electrical energy conversion, mechanical impacts or vibrational behavior are commonly used, and several major problems need to be solved to perform optimal harvesting systems including, but no limited to, primary energy source modeling, energy conversion, and energy storage. It is described a novel C.C. test bench that obtains, in an accurate and automatized process, a generalized linear equivalent electrical model of piezoelectric elements and piezoelectric based energy store harvesting circuits in order to scale energy generation with multiple devices integrated in different topologies.

  7. Charge Capacity of Piezoelectric Membrane Wings

    Science.gov (United States)

    Grybas, Matthew; Hubner, J. Paul

    2015-11-01

    Micro air vehicles (MAVs) have small wings often fabricated with flexible frames and membranes. These membranes flex and vibrate. Piezoelectric films have the ability to convert induced stress or strain into electrical energy. Thus, it is of interest to investigate if piezoelectric films can be used as a structural member of an MAV wing and generate both lift and energy through passive vibrations. Both a shaker test and a wind tunnel test have been conducted to characterize and assess energy production and aerodynamic characteristics including lift, drag and efficiency. The piezoelectric film has been successful as a lifting surface and produces a measurable charge. This work was supported by NSF REU Site Award 1358991.

  8. Piezoelectric energy harvesting computer controlled test bench

    Science.gov (United States)

    Vázquez-Rodriguez, M.; Jiménez, F. J.; de Frutos, J.; Alonso, D.

    2016-09-01

    In this paper a new computer controlled (C.C.) laboratory test bench is presented. The patented test bench is made up of a C.C. road traffic simulator, C.C. electronic hardware involved in automating measurements, and test bench control software interface programmed in LabVIEW™. Our research is focused on characterizing electronic energy harvesting piezoelectric-based elements in road traffic environments to extract (or "harvest") maximum power. In mechanical to electrical energy conversion, mechanical impacts or vibrational behavior are commonly used, and several major problems need to be solved to perform optimal harvesting systems including, but no limited to, primary energy source modeling, energy conversion, and energy storage. It is described a novel C.C. test bench that obtains, in an accurate and automatized process, a generalized linear equivalent electrical model of piezoelectric elements and piezoelectric based energy store harvesting circuits in order to scale energy generation with multiple devices integrated in different topologies.

  9. Flow perfusion culture of human mesenchymal stem cells on silicate-substituted tricalcium phosphate scaffolds

    DEFF Research Database (Denmark)

    Jensen, Lea Bjerre; Bünger, Cody; Kassem, Moustapha

    2008-01-01

    Autologous bone grafts are currently the gold standard for treatment of large bone defects, but their availability is limited due to donor site morbidity. Different substitutes have been suggested to replace these grafts, and this study presents a bone tissue engineered alternative using silicate...

  10. Radial-Electric-Field Piezoelectric Diaphragm Pumps

    Science.gov (United States)

    Bryant, Robert G.; Working, Dennis C.; Mossi, Karla; Castro, Nicholas D.; Mane, Pooma

    2009-01-01

    In a recently invented class of piezoelectric diaphragm pumps, the electrode patterns on the piezoelectric diaphragms are configured so that the electric fields in the diaphragms have symmetrical radial (along-the-surface) components in addition to through-the-thickness components. Previously, it was accepted in the piezoelectric-transducer art that in order to produce the out-of-plane bending displacement of a diaphragm needed for pumping, one must make the electric field asymmetrical through the thickness, typically by means of electrodes placed on only one side of the piezoelectric material. In the present invention, electrodes are placed on both sides and patterned so as to produce substantial radial as well as through-the-thickness components. Moreover, unlike in the prior art, the electric field can be symmetrical through the thickness. Tests have shown in a given diaphragm that an electrode configuration according to this invention produces more displacement than does a conventional one-sided electrode pattern. The invention admits of numerous variations characterized by various degrees of complexity. Figure 1 is a simplified depiction of a basic version. As in other piezoelectric diaphragm pumps of similar basic design, the prime mover is a piezoelectric diaphragm. Application of a suitable voltage to the electrodes on the diaphragm causes it to undergo out-of-plane bending. The bending displacement pushes a fluid out of, or pulls the fluid into, a chamber bounded partly by the diaphragm. Also as in other diaphragm pumps in general, check valves ensure that the fluid flows only in through one port and only out through another port.

  11. Design considerations for piezoelectric polymer ultrasound transducers.

    Science.gov (United States)

    Brown, L F

    2000-01-01

    Much work has been published on the design of ultrasound transducers using piezoelectric ceramics, but a great deal of this work does not apply when using the piezoelectric polymers because of their unique electrical and mechanical properties. The purpose of this paper is to review and present new insight into seven important considerations for the design of active piezoelectric polymer ultrasound transducers: piezoelectric polymer materials selection, transducer construction and packaging requirements, materials characterization and modeling, film thickness and active area design, electroding selection, backing material design, and front protection/matching layer design. Besides reviewing these design considerations, this paper also presents new insight into the design of active piezoelectric polymer ultrasonic transducers. The design and fabrication of an immersible ultrasonic transducer, which has no adhesive layer between the active element and backing layer, is included. The transducer features direct deposition of poly(vinylidene fluoride-trifluoroethylene) [P(VDF-TrFE)] copolymer onto an insulated aluminum backing substrate. Pulse-echo tests indicated a minimum insertion loss of 37 dB and -6 dB bandwidth of 9.8 to 22 MHz (71%). The use of polymer wear-protection/quarter-wave matching layers is also discussed. Test results on a P(VDF-TrFE) transducer showed that a Mylar/sup TM/ front layer provided a slight increase in pulse-echo amplitude of 15% (or 1.2 dB) and an increase in -6 dB pulse-echo fractional bandwidth from 86 to 95%. Theoretical derivations are reported for optimizing the active area of the piezoelectric polymer element for maximum power transfer at resonance. These derivations are extended to the special case for a low profile (i.e., thin) shielded transducer. A method for modeling the non-linear loading effects of a commercial pulser-receiver is also included.

  12. Design, fabrication, and properties of 2-2 connectivity cement/polymer based piezoelectric composites with varied piezoelectric phase distribution

    Energy Technology Data Exchange (ETDEWEB)

    Dongyu, Xu [Shandong Provincial Key Laboratory of Construction Materials Preparation and Measurement, School of Materials Science and Engineering, University of Jinan, Jinan, Shandong 250022 (China); Department of Mechanical Engineering, University of South Carolina, Columbia, South Carolina 29208 (United States); Xin, Cheng; Shifeng, Huang [Shandong Provincial Key Laboratory of Construction Materials Preparation and Measurement, School of Materials Science and Engineering, University of Jinan, Jinan, Shandong 250022 (China); Banerjee, Sourav [Department of Mechanical Engineering, University of South Carolina, Columbia, South Carolina 29208 (United States)

    2014-12-28

    The laminated 2-2 connectivity cement/polymer based piezoelectric composites with varied piezoelectric phase distribution were fabricated by employing Lead Zirconium Titanate ceramic as active phase, and mixture of cement powder, epoxy resin, and hardener as matrix phase with a mass proportion of 4:4:1. The dielectric, piezoelectric, and electromechanical coupling properties of the composites were studied. The composites with large total volume fraction of piezoelectric phase have large piezoelectric strain constant and relative permittivity, and the piezoelectric and dielectric properties of the composites are independent of the dimensional variations of the piezoelectric ceramic layer. The composites with small total volume fraction of piezoelectric phase have large piezoelectric voltage constant, but also large dielectric loss. The composite with gradually increased dimension of piezoelectric ceramic layer has the smallest dielectric loss, and that with the gradually increased dimension of matrix layer has the largest piezoelectric voltage constant. The novel piezoelectric composites show potential applications in fabricating ultrasonic transducers with varied surface vibration amplitude of the transducer.

  13. Novel Approaches to Bone Grafting: Porosity, Bone Morphogenetic Proteins, Stem Cells, and the Periosteum

    OpenAIRE

    Petrochenko, Peter; Narayan, Roger J.

    2010-01-01

    The disadvantages involving the use of a patient’s own bone as graft material have led surgeons to search for alternative materials. In this review, several characteristics of a successful bone graft material are discussed. In addition, novel synthetic materials and natural bone graft materials are being considered. Various factors can determine the success of a bone graft substitute. For example, design considerations such as porosity, pore shape, and interconnection play significant roles i...

  14. Energy harvesting with piezoelectric and pyroelectric materials

    CERN Document Server

    Muensit, Nantakan

    2011-01-01

    The purpose of this book is to present the current state of knowledge in the field of energy harvesting using piezoelectric and pyroelectric materials. The book is addressed to students and academics engaged in research in the fields of energy harvesting, material sciences and engineering. Scientists and engineers who are working in the area of energy conservation and renewable energy resources should find it useful as well. Explanations of fundamental physical properties such as piezoelectricity and pyroelectricity are included to aid the understanding of the non-specialist. Specific technolo

  15. Telescoping cylindrical piezoelectric fiber composite actuator assemblies

    Science.gov (United States)

    Allison, Sidney G. (Inventor); Shams, Qamar A. (Inventor); Fox, Robert L. (Inventor); Fox, legal representative, Christopher L. (Inventor); Fox Chattin, legal representative, Melanie L. (Inventor)

    2010-01-01

    A telescoping actuator assembly includes a plurality of cylindrical actuators in a concentric arrangement. Each cylindrical actuator is at least one piezoelectric fiber composite actuator having a plurality of piezoelectric fibers extending parallel to one another and to the concentric arrangement's longitudinal axis. Each cylindrical actuator is coupled to concentrically-adjacent ones of the cylindrical actuators such that the plurality of cylindrical actuators can experience telescopic movement. An electrical energy source coupled to the cylindrical actuators applies actuation energy thereto to generate the telescopic movement.

  16. Micromechanics-BEM Analysis for Piezoelectric Composites

    Institute of Scientific and Technical Information of China (English)

    QIN Qinghua

    2005-01-01

    The effective material properties of piezoelectric composites are predicted using micromechanics models of the composite structure combined with a boundary element method (BEM) solution of the governing equation. The composites consist of inclusion and matrix phases. The micromechanics method gives formulae for the overall material constants as functions of the concentration matrix, while the boundary element simulation gives numerical solutions of the boundary displacement and electric potential equations for inclusion or hole problems. Numerical results for a piezoelectric plate with circular inclusions are presented to illustrate applications of the proposed micromechanics-BEM formulation.

  17. A Resistivity Gradient Piezoelectric FGM Actuator

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    A resistivity gradient actuator based on lead zirconate titanate ceramics was successfully developed and the bending deflections up to 140 μm were obtained. The actuator material was a matrix of PZT ceramic into which smooth gradient of piezoelectric activity was introduced. The application of an electric field then causes the actuator to bend due to differential strains induced by the piezoelectric effect. The resistivity gradient of the actuator was achieved by doping PZT with suitable donor and acceptor dopants. PZT powder was modified and synthesized by using two stage powder fabrication method. The actuator was fabricated by uniaxial pressing followed by isostatic pressing with two layers of different resistivities.

  18. Reducing the capacitance of piezoelectric film sensors

    Energy Technology Data Exchange (ETDEWEB)

    González, Martín G., E-mail: mggonza@fi.uba.ar [Grupo de Láser, Óptica de Materiales y Aplicaciones Electromagnéticas (GLOMAE), Departamento de Física, Facultad de Ingeniería, Universidad de Buenos Aires, Paseo Colón 850, C1063ACV Buenos Aires (Argentina); Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), C1425FQB Buenos Aires (Argentina); Sorichetti, Patricio A.; Santiago, Guillermo D. [Grupo de Láser, Óptica de Materiales y Aplicaciones Electromagnéticas (GLOMAE), Departamento de Física, Facultad de Ingeniería, Universidad de Buenos Aires, Paseo Colón 850, C1063ACV Buenos Aires (Argentina)

    2016-04-15

    We present a novel design for large area, wideband, polymer piezoelectric sensor with low capacitance. The large area allows better spatial resolution in applications such as photoacoustic tomography and the reduced capacitance eases the design of fast transimpedance amplifiers. The metalized piezoelectric polymer thin film is segmented into N sections, electrically connected in series. In this way, the total capacitance is reduced by a factor 1/N{sup 2}, whereas the mechanical response and the active area of the sensor are not modified. We show the construction details for a two-section sensor, together with the impedance spectroscopy and impulse response experimental results that validate the design.

  19. Characterization of Piezoelectric PDMS-Nanoparticle Composites

    Science.gov (United States)

    Borsa, C. J.; Mionic Ebersold, M.; Bowen, P.; Farine, P.-A.; Briand, D.

    2015-12-01

    In this work, the novel fabrication and characterization of elastomeric piezoelectric nanocomposites are explored. Fabrication methods explored herein utilize ball milled barium titanate powder dispersions, along with double walled carbon nanotubes which are dispersed in toluene though the use of an ultrasonic probe. Test devices are then constructed with electrodes made from evaporated gold on polyimide foils and protective dielectrics of pristine PDMS. Two different device construction methods are explored utilizing both direct contact bonding and plasma bonding of the active composite layers to the dielectric/electrode. Test samples are evaluated through the use of a dedicated Berlincourt type piezoelectric d33 meter.

  20. Piezoelectric Film Waveguides for Surface Acoustic Waves

    Directory of Open Access Journals (Sweden)

    M.F. Zhovnir

    2016-11-01

    Full Text Available The paper presents results of mathematical modeling of piezoelectric film waveguide structures for surface acoustic waves (SAW. Piezoelectric ZnO film is supposed to be placed on a fused quartz substrate. The analytical ratios and numerical results allow to determine the design parameters of the waveguide structures to provide a single-mode SAW propagation mode. The results of amplitude and phase experimental studies of the SAW in the waveguide structures that were carried out on the laser optical sensing set up confirm the theoretical calculations.

  1. Modeling of a piezoelectric micro-scanner

    CERN Document Server

    Chaehoi, A; Cornez, D; Kirk, K

    2008-01-01

    Micro-scanners have been widely used in many optical applications. The micro-scanner presented in this paper uses multimorph-type bending actuators to tilt a square plate mirror. This paper presents a complete analytical model of the piezoelectric micro-scanner. This theoretical model based on strength of material equations calculates the force generated by the multimorphs on the mirror, the profile of the structure and the angular deflection of the mirror. The proposed model, used to optimize the design of the piezoelectric silicon micro-scanner, is intended for further HDL integration, allowing in this way system level simulation and optimization.

  2. Radiation piezoelectric effect in germanium single crystals

    Energy Technology Data Exchange (ETDEWEB)

    Kikoin, I.K.; Kikoin, L.I.; Lazarev, S.D.

    1977-06-01

    Irradiation with ionizing particles of a germanium single crystal and uniaxial deformation at right-angles to the particle beam produced an electric field and a corresponding emf due to the radiation piezoelectric effect. Measurements were carried out when such a single crystal was irradiated with ..cap alpha.. particles and protons. The piezoelectric emf increased linearly with the compressive stress and the ..cap alpha..-particle flux intensity. The emf depended weakly on the particle energy. The observed effect was due to the anisotropy resulting from uniaxial deformation.

  3. Nanogenerator comprising piezoelectric semiconducting nanostructures and Schottky conductive contacts

    Science.gov (United States)

    Wang, Zhong L. (Inventor); Wang, Xudong (Inventor); Song, Jinhui (Inventor); Zhou, Jun (Inventor); He, Jr-Hau (Inventor)

    2011-01-01

    A semiconducting device includes a substrate, a piezoelectric wire, a structure, a first electrode and a second electrode. The piezoelectric wire has a first end and an opposite second end and is disposed on the substrate. The structure causes the piezoelectric wire to bend in a predetermined manner between the first end and the second end so that the piezoelectric wire enters a first semiconducting state. The first electrode is coupled to the first end and the second electrode is coupled to the second end so that when the piezoelectric wire is in the first semiconducting state, an electrical characteristic will be exhibited between the first electrode and the second electrode.

  4. Self-oscillating loop based piezoelectric power converter

    DEFF Research Database (Denmark)

    2013-01-01

    The present invention relates to a piezoelectric power converter comprising an input driver electrically coupled directly to an input or primary electrode of the piezoelectric transformer without any intervening series or parallel inductor. A feedback loop is operatively coupled between an output...... voltage of the piezoelectric transformer and the input driver to provide a self-oscillation loop around a primary section of the piezoelectric transformer oscillating at an excitation frequency. Electrical characteristics of the feedback loop are configured to set the excitation frequency of the self......- oscillation loop within a zero-voltage-switching (ZVS) operation range of the piezoelectric transformer....

  5. The development of piezoelectric crystal gyroscopes in China

    Science.gov (United States)

    Chen, Feng-Yu; Qing, Rong-Kang

    The operation principles and basic characteristics of a newly-developed vibrating-beam piezoelectric crystal angular rate gyroscope are discussed along with the gyroscope applications. Several applications of piezoelectric gyroscopes are described, including its use as a telemetering sensor, attidude measuring device in automobiles, in geological exploraton drilling, and as a sensing element in ship and aircraft control systems. Specifications are presented for several gyroscopes, including those for two piezoelectric angular rate gyros with different applications (telemetering and control), a typical piezoelectric angular displacement gyro, and a piezoelectric inclinometer.

  6. Dynamic studies on the influence of strain on superconducting properties using piezoelectric substrates

    Energy Technology Data Exchange (ETDEWEB)

    Trommler, Sascha; Huehne, Ruben; Iida, Kazumasa; Haindl, Silvia; Haenisch, Jens; Pahlke, Patrick; Thersleff, Thomas; Schultz, Ludwig; Holzapfel, Bernhard [IFW Dresden (Germany)

    2011-07-01

    The interplay between structural parameters and superconducting properties attracts high interest in particular regarding the iron based superconductors. In contrast to the cuprate family, superconductivity of the latter can be induced using either pressure or chemical substitution. Nevertheless little is known about this relationship when biaxial strain is applied. The generation of biaxial strain by the preparation of thin films on substrates with different lattice mismatch is well established for cuprates. However, high quality films are necessary to correlate structural changes with electronic properties. In this work an alternative approach is used. Single crystalline piezoelectric substrates offer the unique opportunity to tune the lattice parameters continuously using the inverse piezoelectric effect. We prepared thin epitaxial La{sub 1-x}Sr{sub x}CuO{sub 4} and BaFe{sub 2-x}Co{sub x}As{sub 2} films on piezoelectric (001) Pb(Mg{sub 1/3}Nb{sub 2/3}){sub 0.72}Ti{sub 0.28}O{sub 3} (PMN-PT) substrates. A reversible shift of the superconducting transition has been achieved with a value of 0.44 K for La{sub 1.85}Sr{sub 0.15}CuO{sub 4} and 0.2 K for BaFe{sub 1.8}Co{sub 0.2}As{sub 2} for a biaxial strain of 0.022% and 0.017%, respectively.

  7. Lattice Strain Induced Remarkable Enhancement in Piezoelectric Performance of ZnO-Based Flexible Nanogenerators.

    Science.gov (United States)

    Zhang, Yang; Liu, Caihong; Liu, Jingbin; Xiong, Jie; Liu, Jingyu; Zhang, Ke; Liu, Yudong; Peng, Mingzeng; Yu, Aifang; Zhang, Aihua; Zhang, Yan; Wang, Zhiwei; Zhai, Junyi; Wang, Zhong Lin

    2016-01-20

    In this work, by employing halogen elements (fluorine, chlorine, bromine, and iodine) as dopant we demonstrate a unique strategy to enhance the output performance of ZnO-based flexible piezoelectric nanogenerators. For a halogen-doped ZnO nanowire film, dopants and doping concentration dependent lattice strain along the ZnO c-axis are established and confirmed by the EDS, XRD, and HRTEM analysis. Although lattice strain induced charge separation was theoretically proposed, it has not been experimentally investigated for wurtzite structured ZnO nanomaterials. Tuning the lattice strain from compressive to tensile state along the ZnO c-axis can be achieved by a substitution of halogen dopant from fluorine to other halogen elements due to the ionic size difference between dopants and oxygen. With its focus on a group of nonmetal element induced lattice strain in ZnO-based nanomaterials, this work paves the way for enhancing the performance of wurtzite-type piezoelectric semiconductor nanomaterials via lattice strain strategy which can be employed to construct piezoelectric nanodevices with higher efficiency in a cost-effective manner.

  8. TECHNICAL NOTE: Dielectric and piezoelectric properties of piezoelectric ceramic sulphoaluminate cement composites

    Science.gov (United States)

    Cheng, Xin; Huang, Shifeng; Chang, Jun; Lu, Lingchao; Liu, Futian; Ye, Zengmao; Wang, Shoude

    2005-10-01

    Using cement as the matrix of piezoelectric smart composites can solve the problem of mismatch of smart composites and concrete structure in civil engineering. 0 3 cement based piezoelectric composites were fabricated by a compression technique using PMN and sulphoaluminate cement as raw materials. The influence of the PMN content on the dielectric and piezoelectric properties of the composites was investigated. The temperature dependence of the dielectric properties of the composites was discussed in detail. The results indicate that the dielectric constants are almost constant in the temperature range from -30 to 50 °C, which shows excellent dielectric temperature stability. With increasing PMN content, the piezoelectric and dielectric properties of the composites increase. The theoretical values of the dielectric constants show good agreement with the experimental values for the composites.

  9. Fundamentals of piezoelectric sensorics mechanical, dielectric, and thermodynamical properties of piezoelectric materials

    CERN Document Server

    Tichý, Jan; Kittinger, Erwin; Prívratská, Jana; Privatska, Jana; Janovec, Vaclav

    2010-01-01

    This book presents the physics of piezoleletric sensors in a straight-forward and easy-to-grasp way, from the fundamentals of phenomenological crystal physics through more complex concepts, to its explanation of several important piezoelectric materials.

  10. Medicineringsfejl ved generisk substitution

    DEFF Research Database (Denmark)

    Rölfing, Jan

    2012-01-01

    Generic substitution is a major cause of medical mistakes in the general population. Danish legislation obligates pharmacies to substitute prescribed medicine with the cheapest equivalent formulation, despite variations in product name, packaging, shape and colour. Consequently, medical mistakes ...... occur. Scientific evidence on the consequences of generic substitution is sparse. Call upon fellow health workers to report medical mistakes to the national entities and scientific peers, in order to increase awareness and scientific evidence about the problem....

  11. A Novel Approach to a Piezoelectric Sensing Element

    Directory of Open Access Journals (Sweden)

    M. Martinez

    2010-01-01

    Full Text Available Piezoelectric materials have commonly been used in pressure and stress sensors; however, many designs consist of thin plate structures that produce small voltage signals when they are compressed or extended under a pressure field. This study used finite element methods to design a novel piezoelectric pressure sensor with a C-shaped piezoelectric element and determine if the voltage signal obtained during hydrostatic pressure application was enhanced compared to a standard thin plate piezoelectric element. The results of this study demonstrated how small deformations of this C-shaped sensor produced a large electrical signal output. It was also shown that the location of the electrodes for this sensor needs to be carefully chosen and that the electric potential distribution varies depending on the poling of the piezoelectric element. This study indicated that the utilization of piezoelectric materials of different shapes and geometries embedded in a polymer matrix for sensing applications has several advantages over thin plate solid piezoelectric structures.

  12. Modeling of composite piezoelectric structures with the finite volume method.

    Science.gov (United States)

    Bolborici, Valentin; Dawson, Francis P; Pugh, Mary C

    2012-01-01

    Piezoelectric devices, such as piezoelectric traveling- wave rotary ultrasonic motors, have composite piezoelectric structures. A composite piezoelectric structure consists of a combination of two or more bonded materials, at least one of which is a piezoelectric transducer. Piezoelectric structures have mainly been numerically modeled using the finite element method. An alternative approach based on the finite volume method offers the following advantages: 1) the ordinary differential equations resulting from the discretization process can be interpreted directly as corresponding circuits; and 2) phenomena occurring at boundaries can be treated exactly. This paper presents a method for implementing the boundary conditions between the bonded materials in composite piezoelectric structures modeled with the finite volume method. The paper concludes with a modeling example of a unimorph structure.

  13. A review on one dimensional perovskite nanocrystals for piezoelectric applications

    Directory of Open Access Journals (Sweden)

    Li-Qian Cheng

    2016-03-01

    Full Text Available In recent years, one-dimensional piezoelectric nanomaterials have become a research topic of interest because of their special morphology and excellent piezoelectric properties. This article presents a short review on one dimensional perovskite piezoelectric materials in different systems including Pb(Zr,TiO3, BaTiO3 and (K,NaNbO3 (KNN. We emphasize KNN as a promising lead-free piezoelectric compound with a high Curie temperature and high piezoelectric properties and describe its synthesis and characterization. In particular, details are presented for nanoscale piezoelectricity characterization of a single KNN nanocrystal by piezoresponse force microscopy. Finally, this review describes recent progress in applications based on one dimensional piezoelectric nanostructures with a focus on energy harvesting composite materials.

  14. Cyclotomic Aperiodic Substitution Tilings

    Directory of Open Access Journals (Sweden)

    Stefan Pautze

    2017-01-01

    Full Text Available The class of Cyclotomic Aperiodic Substitution Tilings (CASTs is introduced. Its vertices are supported on the 2 n -th cyclotomic field. It covers a wide range of known aperiodic substitution tilings of the plane with finite rotations. Substitution matrices and minimal inflation multipliers of CASTs are discussed as well as practical use cases to identify specimen with individual dihedral symmetry D n or D 2 n , i.e., the tiling contains an infinite number of patches of any size with dihedral symmetry D n or D 2 n only by iteration of substitution rules on a single tile.

  15. Piezoelectric multilayer actuator life test.

    Science.gov (United States)

    Sherrit, Stewart; Bao, Xiaoqi; Jones, Christopher M; Aldrich, Jack B; Blodget, Chad J; Moore, James D; Carson, John W; Goullioud, Renaud

    2011-04-01

    Potential NASA optical missions such as the Space Interferometer Mission require actuators for precision positioning to accuracies of the order of nanometers. Commercially available multilayer piezoelectric stack actuators are being considered for driving these precision mirror positioning mechanisms. These mechanisms have potential mission operational requirements that exceed 5 years for one mission life. To test the feasibility of using these commercial actuators for these applications and to determine their reliability and the redundancy requirements, a life test study was undertaken. The nominal actuator requirements for the most critical actuators on the Space Interferometry Mission (SIM) in terms of number of cycles was estimated from the Modulation Optics Mechanism (MOM) and Pathlength control Optics Mechanism (POM) and these requirements were used to define the study. At a nominal drive frequency of 250 Hz, one mission life is calculated to be 40 billion cycles. In this study, a set of commercial PZT stacks configured in a potential flight actuator configuration (pre-stressed to 18 MPa and bonded in flexures) were tested for up to 100 billion cycles. Each test flexure allowed for two sets of primary and redundant stacks to be mechanically connected in series. The tests were controlled using an automated software control and data acquisition system that set up the test parameters and monitored the waveform of the stack electrical current and voltage. The samples were driven between 0 and 20 V at 2000 Hz to accelerate the life test and mimic the voltage amplitude that is expected to be applied to the stacks during operation. During the life test, 10 primary stacks were driven and 10 redundant stacks, mechanically in series with the driven stacks, were open-circuited. The stroke determined from a strain gauge, the temperature and humidity in the chamber, and the temperature of each individual stack were recorded. Other properties of the stacks, including the

  16. Fabrication and characterization of a piezoelectric accelerometer

    DEFF Research Database (Denmark)

    Reus, Roger De; Gulløv, Jens; Scheeper, Patrick

    1999-01-01

    Zinc oxide based piezoelectric accelerometers were fabricated by bulk micromachining. A high yield was obtained in a relatively simple process sequence. For two electrode configurations a direction selectivity better than 100 was obtained for acceleration in the vertical direction and a selectivity...

  17. Development of a Piezoelectric Rotary Hammer Drill

    Science.gov (United States)

    Domm, Lukas N.

    2011-01-01

    The Piezoelectric Rotary Hammer Drill is designed to core through rock using a combination of rotation and high frequency hammering powered by a single piezoelectric actuator. It is designed as a low axial preload, low mass, and low power device for sample acquisition on future missions to extraterrestrial bodies. The purpose of this internship is to develop and test a prototype of the Piezoelectric Rotary Hammer Drill in order to verify the use of a horn with helical or angled cuts as a hammering and torque inducing mechanism. Through an iterative design process using models in ANSYS Finite Element software and a Mason's Equivalent Circuit model in MATLAB, a horn design was chosen for fabrication based on the predicted horn tip motion, electromechanical coupling, and neutral plane location. The design was then machined and a test bed assembled. The completed prototype has proven that a single piezoelectric actuator can be used to produce both rotation and hammering in a drill string through the use of a torque inducing horn. Final data results include bit rotation produced versus input power, and best drilling rate achieved with the prototype.

  18. Piezoelectricity in Two-Dimensional Materials

    KAUST Repository

    Wu, Tao

    2015-02-25

    Powering up 2D materials: Recent experimental studies confirmed the existence of piezoelectricity - the conversion of mechanical stress into electricity - in two-dimensional single-layer MoS2 nanosheets. The results represent a milestone towards embedding low-dimensional materials into future disruptive technologies. © 2015 Wiley-VCH Verlag GmbH & Co. KGaA.

  19. Rotor damage detection by using piezoelectric impedance

    Science.gov (United States)

    Qin, Y.; Tao, Y.; Mao, Y. F.

    2016-04-01

    Rotor is a core component of rotary machinery. Once the rotor has the damage, it may lead to a major accident. Thus the quantitative rotor damage detection method based on piezoelectric impedance is studied in this paper. With the governing equation of piezoelectric transducer (PZT) in a cylindrical coordinate, the displacement along the radius direction is derived. The charge of PZT is calculated by the electric displacement. Then, by the use of the obtained displacement and charge, an analytic piezoelectric impedance model of the rotor is built. Given the circular boundary condition of a rotor, annular elements are used as the analyzed objects and spectral element method is used to set up the damage detection model. The Electro-Mechanical (E/M) coupled impedance expression of an undamaged rotor is deduced with the application of a low-cost impedance test circuit. A Taylor expansion method is used to obtain the approximate E/M coupled impedance expression for the damaged rotor. After obtaining the difference between the undamaged and damaged rotor impedance, a rotor damage detection method is proposed. This method can directly calculate the change of bending stiffness of the structural elements, it follows that the rotor damage can be effectively detected. Finally, a preset damage configuration is used for the numerical simulation. The result shows that the quantitative damage detection algorithm based on spectral element method and piezoelectric impedance proposed in this paper can identify the location and the severity of the damaged rotor accurately.

  20. Piezoelectric actuators control applications of smart materials

    CERN Document Server

    Choi, Seung-Bok

    2010-01-01

    Newer classes of smart materials are beginning to display the capacity for self-repair, self-diagnosis, self-multiplication, and self-degradation. While there are other candidates, piezoelectric actuators and sensors are proving to be the best choice. This title details the authors' research and development in this area.

  1. Piezoelectric Nanoparticle-Polymer Composite Materials

    Science.gov (United States)

    McCall, William Ray

    Herein we demonstrate that efficient piezoelectric nanoparticle-polymer composite materials can be synthesized and fabricated into complex microstructures using sugar-templating methods or optical printing techniques. Stretchable foams with excellent tunable piezoelectric properties are created by incorporating sugar grains directly into polydimethylsiloxane (PDMS) mixtures containing barium titanate (BaTiO3 -- BTO) nanoparticles and carbon nanotubes (CNTs), followed by removal of the sugar after polymer curing. Porosities and elasticity are tuned by simply adjusting the sugar/polymer mass ratio and the electrical performance of the foams showed a direct relationship between porosity and the piezoelectric outputs. User defined 2D and 3D optically printed piezoelectric microstructures are also fabricated by incorporating BTO nanoparticles into photoliable polymer solutions such as polyethylene glycol diacrylate (PEGDA) and exposing to digital optical masks that can be dynamically altered. Mechanical-to-electrical conversion efficiency of the optically printed composite is enhanced by chemically altering the surface of the BTO nanoparticles with acrylate groups which form direct covalent linkages with the polymer matrix under light exposure. Both of these novel materials should find exciting uses in a variety of applications including energy scavenging platforms, nano- and microelectromechanical systems (NEMS/MEMS), sensors, and acoustic actuators.

  2. Flow Energy Piezoelectric Bimorph Nozzle Harvester

    Science.gov (United States)

    Sherrit, Stewart; Lee, Hyeong Jae; Kim, Namhyo; Sun, Kai; Corbett, Gary; Walkemeyer, Phillip; Hasenoehrl, Jennifer; Hall, Jeffery L.; Colonius, Tim; Tosi, Luis Phillipe; Arrazola, Alvaro

    2014-01-01

    There is a need for a long-life power generation scheme that could be used downhole in an oil well to produce 1 Watt average power. There are a variety of existing or proposed energy harvesting schemes that could be used in this environment but each of these has its own limitations. The vibrating piezoelectric structure is in principle capable of operating for very long lifetimes (decades) thereby possibly overcoming a principle limitation of existing technology based on rotating turbo-machinery. In order to determine the feasibility of using piezoelectrics to produce suitable flow energy harvesting, we surveyed experimentally a variety of nozzle configurations that could be used to excite a vibrating piezoelectric structure in such a way as to enable conversion of flow energy into useful amounts of electrical power. These included reed structures, spring mass-structures, drag and lift bluff bodies and a variety of nozzles with varying flow profiles. Although not an exhaustive survey we identified a spline nozzle/piezoelectric bimorph system that experimentally produced up to 3.4 mW per bimorph. This paper will discuss these results and present our initial analyses of the device using dimensional analysis and constitutive electromechanical modeling. The analysis suggests that an order-of-magnitude improvement in power generation from the current design is possible.

  3. Power performance of circular piezoelectric diaphragm generators

    Institute of Scientific and Technical Information of China (English)

    Kehong TANG; Junwu KAN; Taijiang PENG; Zhigang YANG; Guangming CHENG

    2008-01-01

    Energy generation performance of a piezo-electric generator depends mainly on several elements such as the structural style, boundary conditions, geo-metry parameters, materials, vibration-source frequency, and external load. To obtain the optimal energy-harvest-ing device, the Raleigh method is used to establish the analysis model of circular piezoelectric composite dia-phragms. Simply supported and clamped boundary con-ditions were considered. The relationships between the output power and the structural parameters of piezo-electric composite diaphragms, and the external load res-istance and frequency were shown. Given the correlative material parameters and boundary conditions, the output power, using structural parameters, external load, or vibrating frequency as variables, can be calculated. Simulation results show that there are optimal structural parameters and load for a composite diaphragm to achieve the maximum output power. A piezoelectric dia-phragm generator with given dimensions tends to achieve higher output power under clamped boundary conditions than that under simply supported boundary conditions.

  4. Preliminary investigations of piezoelectric based LED luminary

    DEFF Research Database (Denmark)

    Nielsen, Dennis; Andersen, Michael A. E.; Meyer, Kaspar Sinding

    2011-01-01

    This paper presents a preliminary study of PT (Piezoelectric Transformer) based SMPS’s (Switch Mode Power Supplies) for LED luminary. The unique properties of PTs (efficiency, power density and EMI) make them highly suitable for this application. Power stage topologies, rectifiers circuits, modul...

  5. A New Annular Shear Piezoelectric Accelerometer

    DEFF Research Database (Denmark)

    Liu, Bin; Kriegbaum, B.

    2000-01-01

    This paper describes the construction and performance of a recently introduced Annular Shear piezoelectric accelerometer, Type 4511. The design has insulated and double-shielded case. The accelerometer housing is made of stainless steel, AISI 316L. Piezoceramic PZ23 is used. The seismic mass...... interface for sensors including mixed-mode communication protocols and transducer electronic data sheet (TEDS)....

  6. Bone scan

    Science.gov (United States)

    ... legs, or spine fractures) Diagnose a bone infection (osteomyelitis) Diagnose or determine the cause of bone pain, ... 2015:chap 43. Read More Broken bone Metabolism Osteomyelitis Review Date 12/10/2015 Updated by: Jatin ...

  7. Bone Cancer

    Science.gov (United States)

    Cancer that starts in a bone is uncommon. Cancer that has spread to the bone from another ... more common. There are three types of bone cancer: Osteosarcoma - occurs most often between ages 10 and ...

  8. Bone Diseases

    Science.gov (United States)

    Your bones help you move, give you shape and support your body. They are living tissues that rebuild constantly ... childhood and your teens, your body adds new bone faster than it removes old bone. After about ...

  9. Bone Markers

    Science.gov (United States)

    ... markers may be seen in conditions such as: Osteoporosis Paget disease Cancer that has spread to the bone (metastatic bone disease) Hyperparathyroidism Hyperthyroidism Osteomalacia in adults and rickets in children—lack of bone mineralization, ...

  10. Cement from magnesium substituted hydroxyapatite.

    Science.gov (United States)

    Lilley, K J; Gbureck, U; Knowles, J C; Farrar, D F; Barralet, J E

    2005-05-01

    Brushite cement may be used as a bone graft material and is more soluble than apatite in physiological conditions. Consequently it is considerably more resorbable in vivo than apatite forming cements. Brushite cement formation has previously been reported by our group following the mixture of nanocrystalline hydroxyapatite and phosphoric acid. In this study, brushite cement was formed from the reaction of nanocrystalline magnesium-substituted hydroxyapatite with phosphoric acid in an attempt to produce a magnesium substituted brushite cement. The presence of magnesium was shown to have a strong effect on cement composition and strength. Additionally the presence of magnesium in brushite cement was found to reduce the extent of brushite hydrolysis resulting in the formation of HA. By incorporating magnesium ions in the apatite reactant structure the concentration of magnesium ions in the liquid phase of the cement was controlled by the dissolution rate of the apatite. This approach may be used to supply other ions to cement systems during setting as a means to manipulate the clinical performance and characteristics of brushite cements.

  11. Algebraic Construction and Cryptographic Properties of Rijndael Substitution Box

    Directory of Open Access Journals (Sweden)

    Shristi Deva Sinha

    2012-01-01

    Full Text Available Rijndael algorithm was selected as the advanced encryption standard in 2001 after five year long security evaluation; it is well proven in terms of its strength and efficiency. The substitution box is the back bone of the cipher and its strength lies in the simplicity of its algebraic construction. The present paper is a study of the construction of Rijndael Substitution box and the effect of varying the design components on its cryptographic properties.

  12. Planar Rotary Piezoelectric Motor Using Ultrasonic Horns

    Science.gov (United States)

    Sherrit, Stewart; Bao, Xiaoqi; Badescu, Mircea; Bar-Cohen, Yoseph; Geiyer, Daniel; Ostlund, Patrick N.; Allen, Phillip

    2011-01-01

    A motor involves a simple design that can be embedded into a plate structure by incorporating ultrasonic horn actuators into the plate. The piezoelectric material that is integrated into the horns is pre-stressed with flexures. Piezoelectric actuators are attractive for their ability to generate precision high strokes, torques, and forces while operating under relatively harsh conditions (temperatures at single-digit K to as high as 1,273 K). Electromagnetic motors (EM) typically have high rotational speed and low torque. In order to produce a useful torque, these motors are geared down to reduce the speed and increase the torque. This gearing adds mass and reduces the efficiency of the EM. Piezoelectric motors can be designed with high torques and lower speeds directly without the need for gears. Designs were developed for producing rotary motion based on the Barth concept of an ultrasonic horn driving a rotor. This idea was extended to a linear motor design by having the horns drive a slider. The unique feature of these motors is that they can be designed in a monolithic planar structure. The design is a unidirectional motor, which is driven by eight horn actuators, that rotates in the clockwise direction. There are two sets of flexures. The flexures around the piezoelectric material are pre-stress flexures and they pre-load the piezoelectric disks to maintain their being operated under compression when electric field is applied. The other set of flexures is a mounting flexure that attaches to the horn at the nodal point and can be designed to generate a normal force between the horn tip and the rotor so that to first order it operates independently and compensates for the wear between the horn and the rotor.

  13. Integration of bulk piezoelectric materials into microsystems

    Science.gov (United States)

    Aktakka, Ethem Erkan

    Bulk piezoelectric ceramics, compared to deposited piezoelectric thin-films, provide greater electromechanical coupling and charge capacity, which are highly desirable in many MEMS applications. In this thesis, a technology platform is developed for wafer-level integration of bulk piezoelectric substrates on silicon, with a final film thickness of 5-100microm. The characterized processes include reliable low-temperature (200°C) AuIn diffusion bonding and parylene bonding of bulk-PZT on silicon, wafer-level lapping of bulk-PZT with high-uniformity (+/-0.5microm), and low-damage micro-machining of PZT films via dicing-saw patterning, laser ablation, and wet-etching. Preservation of ferroelectric and piezoelectric properties is confirmed with hysteresis and piezo-response measurements. The introduced technology offers higher material quality and unique advantages in fabrication flexibility over existing piezoelectric film deposition methods. In order to confirm the preserved bulk properties in the final film, diaphragm and cantilever beam actuators operating in the transverse-mode are designed, fabricated and tested. The diaphragm structure and electrode shapes/sizes are optimized for maximum deflection through finite-element simulations. During tests of fabricated devices, greater than 12microm PP displacement is obtained by actuation of a 1mm2 diaphragm at 111kHz with management IC, which incorporates a supply-independent bias circuitry, an active diode for low-dropout rectification, a bias-flip system for higher efficiency, and a trickle battery charger. The overall system does not require a pre-charged battery, and has power consumption of sleep-mode (simulated). Under lg vibration at 155Hz, a 70mF ultra-capacitor is charged from OV to 1.85V in 50 minutes.

  14. Novel approaches to bone grafting: porosity, bone morphogenetic proteins, stem cells, and the periosteum.

    Science.gov (United States)

    Petrochenko, Peter; Narayan, Roger J

    2010-01-01

    The disadvantages involving the use of a patient's own bone as graft material have led surgeons to search for alternative materials. In this review, several characteristics of a successful bone graft material are discussed. In addition, novel synthetic materials and natural bone graft materials are being considered. Various factors can determine the success of a bone graft substitute. For example, design considerations such as porosity, pore shape, and interconnection play significant roles in determining graft performance. The effective delivery of bone morphogenetic proteins and the ability to restore vascularization also play significant roles in determining the success of a bone graft material. Among current approaches, shorter bone morphogenetic protein sequences, more efficient delivery methods, and periosteal graft supplements have shown significant promise for use in autograft substitutes or autograft extenders.

  15. Calcitonin substitution in calcitonin deficiency reduces particle-induced osteolysis

    Directory of Open Access Journals (Sweden)

    Grabellus Florian

    2011-08-01

    Full Text Available Abstract Background Periprosthetic osteolysis is a major cause of aseptic loosening in joint arthroplasty. This study investigates the impact of CT (calcitonin deficiency and CT substitution under in-vivo circumstances on particle-induced osteolysis in Calca -/- mice. Methods We used the murine calvarial osteolysis model based on ultra-high molecular weight polyethylene (UHMWPE particles in 10 C57BL/6J wild-type (WT mice and twenty Calca -/- mice. The mice were divided into six groups: WT without UHMWPE particles (Group 1, WT with UHMWPE particles (Group 2, Calca -/- mice without UHMWPE particles (Group 3, Calca -/- mice with UHMWPE particles (Group 4, Calca -/- mice without UHMWPE particles and calcitonin substitution (Group 5, and Calca -/- mice with UHMWPE particle implantation and calcitonin substitution (Group 6. Analytes were extracted from serum and urine. Bone resorption was measured by bone histomorphometry. The number of osteoclasts was determined by counting the tartrate-resistant acid phosphatase (TRACP + cells. Results Bone resorption was significantly increased in Calca -/- mice compared with their corresponding WT. The eroded surface in Calca -/- mice with particle implantation was reduced by 20.6% after CT substitution. Osteoclast numbers were significantly increased in Calca -/- mice after particle implantation. Serum OPG (osteoprotegerin increased significantly after CT substitution. Conclusions As anticipated, Calca -/- mice show extensive osteolysis compared with wild-type mice, and CT substitution reduces particle-induced osteolysis.

  16. Bone Marrow Concentrate and Bovine Bone Mineral for Sinus Floor Augmentation : A Controlled, Randomized, Single-Blinded Clinical and Histological Trial-Per-Protocol Analysis

    NARCIS (Netherlands)

    Sauerbier, Sebastian; Rickert, Daniela; Gutwald, Ralf; Nagursky, Heiner; Oshima, Toshiyuki; Xavier, Samuel P.; Christmann, Johannes; Kurz, Patrick; Menne, Dieter; Vissink, Arjan; Raghoebar, Gerry; Schmelzeisen, Rainer; Wagner, Wilfried; Koch, Felix P.

    2011-01-01

    Purpose: The purpose of this work was to evaluate the potential of substituting autogenous bone (AB) by bone marrow aspirate concentrate (BMAC). Both AB and BMAC were tested in combination with a bovine bone mineral (BBM) for their ability of new bone formation (NBF) in a multicentric, randomized, c

  17. Design of Floating Mass Type Piezoelectric Actuator for Implantable Middle Ear Hearing Devices

    Institute of Scientific and Technical Information of China (English)

    LIU Houguang; TA Na; MING Xiaofeng; RAO Zhushi

    2009-01-01

    To overcome some of the problems inherent in conventional hearing aids such as low gain at high frequencies due to acoustic feedback, discomfort in occlusion of the external ear canal and so on, implantable middle ear hearing devices (IMEHDs) have been developed over the past two decades. For such kinds of IMEHDS, this paper presents the design of a floating mass piezoelectric actuator using a PMN-30%PT stack as a new type of vibrator. The proposed piezoelectric actuator consists of only three components of a piezoelectric stack, a metal case and a clamp. For the purpose of aiding the design of this actuator, a coupling biomechanics model of human middle ear and the piezoelectric actuator was constructed. This model was built based on a complete set of computerized tomography section images of a healthy volunteer's left ear by reverse engineering technology. The validity of this model was confirmed by comparing the motion of the tympanic membrane and stapes footplate obtained by this model with published experimental measurements on human temporal bones. It is shown that the designed actuator can be implanted on the incus long process by a simple surgical operation, and the stapes footplate displacement by its excitation at 10.5 V root-mean-square(RMS) voltage was equivalent to that from acoustic stimulation at 100 dB sound pressure level(SPL), which is adequate stimulation to the nssicular chain. The corresponding power consumption is 0.04 mW per volt of excitation at 1 kHz, which is low enough for the transducer to be used in an implantable middle ear device.

  18. Structure Construction and Position Signals Analysis of the Single-Axis Piezoelectric Actuated Stage by using a novel Piezoelectric Actuator

    Directory of Open Access Journals (Sweden)

    Shann-Chyi Mou

    2013-09-01

    Full Text Available In this study, a novel piezoelectric actuator structure -4-9-9-14 piezoelectric actuator is constructed and it is made of piezoelectric buzzer to drive a piezoelectric actuated stage. The 4-9-9-14 piezoelectric actuator offers a better balanced capability of forward rotation and reverse rotation than the conventional edge-driving piezoelectric actuator. According to the rotational speed experiment, the CW/CCW ratio of the 4-9-9-14 piezoelectric actuator is probably 1: 0.8. The movement of the piezoelectric actuated stage is read and analyzed by means of data acquisition card and LabVIEW software operating in conjunction with a linear encoder. In a natural environment, plenty of noise interferes with linear encoder signals and results in erroneous addition performed by a counter. Therefore, the LabVIEW program set forth the means of filtering and the method for retrieving a correct position signal. The piezoelectric actuated stage by using 4-9-9-14 piezoelectric actuator can be expanded and applied easily to a longer distance moved stage.

  19. Investigating the Electromechanical Coupling in Piezoelectric Actuator Drive Motor Under Heavy Load

    DEFF Research Database (Denmark)

    Zsurzsan, Tiberiu-Gabriel; Andersen, Michael A. E.; Zhang, Zhe;

    2014-01-01

    The Piezoelectric Actuator Drive (PAD) is an accurate, high-torque rotary piezoelectric motor that employs piezoelectric stack actuators and inverse hypocycloidal motion to generate rotation. Important factors that determine motor performance are the proper concentric alignment between the motor...

  20. Investigating the Electromechanical Coupling in Piezoelectric Actuator Drive Motor Under Heavy Load

    DEFF Research Database (Denmark)

    Zsurzsan, Tiberiu-Gabriel; Andersen, Michael A. E.; Zhang, Zhe;

    2014-01-01

    The Piezoelectric Actuator Drive (PAD) is an accurate, high-torque rotary piezoelectric motor that employs piezoelectric stack actuators and inverse hypocycloidal motion to generate rotation. Important factors that determine motor performance are the proper concentric alignment between the motor ...

  1. Interaction between a piezoelectric screw dislocation and a finite crack with surface piezoelectricity

    Science.gov (United States)

    Wang, Xu; Xu, Yang

    2015-12-01

    We analytically investigate the contribution of surface piezoelectricity to the interaction between a piezoelectric screw dislocation and a finite crack in a hexagonal piezoelectric solid. The piezoelectric screw dislocation suffers jumps in the displacement and in the electric potential across the slip plane, and meanwhile it is subjected to a line force and a line charge at its core. The original boundary value problem is reduced to two sets of coupled first-order Cauchy singular integro-differential equations by considering a distribution of line dislocations, electric-potential-dislocations, line forces and line charges on the crack. By using a diagonalization method, the two sets of equations are decoupled into four independent singular integro-differential equations, each of which can be numerically solved by means of the collocation method. Our analysis reveals that in general the stresses, strains, electric displacements and electric fields exhibit both the weak logarithmic and the strong square root singularities at the two crack tips. The image force acting on the piezoelectric screw dislocation due to its interaction with the finite crack is calculated.

  2. The giant piezoelectric effect: electric field induced monoclinic phase or piezoelectric distortion of the rhombohedral parent?

    CERN Document Server

    Kisi, E H; Forrester, J S; Howard, C J

    2003-01-01

    Lead zinc niobate-lead titanate (PZN-PT) single crystals show very large piezoelectric strains for electric fields applied along the unit cell edges e.g. [001] sub R. It has been widely reported that this effect is caused by an electric field induced phase transition from rhombohedral (R3m) to monoclinic (Cm or Pm) symmetry in an essentially continuous manner. Group theoretical analysis using the computer program ISOTROPY indicates phase transitions between R3m and Cm (or Pm) must be discontinuous under Landau theory. An analysis of the symmetry of a strained unit cell in R3m and a simple expansion of the piezoelectric strain equation indicate that the piezoelectric distortion due to an electric field along a cell edge in rhombohedral perovskite-based ferroelectrics is intrinsically monoclinic (Cm), even for infinitesimal electric fields. PZN-PT crystals have up to nine times the elastic compliance of other piezoelectric perovskites and it might be expected that the piezoelectric strains are also very large. ...

  3. High-Temperature Piezoelectric Crystals for Acoustic Wave Sensor Applications.

    Science.gov (United States)

    Zu, Hongfei; Wu, Huiyan; Wang, Qing-Ming

    2016-03-01

    In this review paper, nine different types of high-temperature piezoelectric crystals and their sensor applications are overviewed. The important materials' properties of these piezoelectric crystals including dielectric constant, elastic coefficients, piezoelectric coefficients, electromechanical coupling coefficients, and mechanical quality factor are discussed in detail. The determination methods of these physical properties are also presented. Moreover, the growth methods, structures, and properties of these piezoelectric crystals are summarized and compared. Of particular interest are langasite and oxyborate crystals, which exhibit no phase transitions prior to their melting points ∼ 1500 °C and possess high electrical resistivity, piezoelectric coefficients, and mechanical quality factor at ultrahigh temperature ( ∼ 1000 °C). Finally, some research results on surface acoustic wave (SAW) and bulk acoustic wave (BAW) sensors developed using this high-temperature piezoelectric crystals are discussed.

  4. Piezoelectric effects and electromechanical theories at the nanoscale.

    Science.gov (United States)

    Zhang, Jin; Wang, Chengyuan; Bowen, Chris

    2014-11-21

    Considerable effort has been made to study the piezoelectric effect on the nanoscale, which serves as a physical basis for a wide range of smart nanodevices and nanoelectronics. This paper reviews recent progress in the research on the piezoelectric properties and electromechanical effects of piezoelectric nanomaterials (PNs). The review begins with an introduction to existing PNs which exhibit a diverse range of atomic structures and configurations. The nanoscale measurement of their effective piezoelectric coefficients (EPCs) is summarised with an emphasis on the major factors determining the piezoelectric properties of PNs. The paper concludes with a review of the electromechanical theories that are able to capture the small-scale effects on PNs, which include the surface piezoelectricity, flexoelectricity and Eringen's nonlocal theory. In contrast to the classical theories, two types of EPCs are defined, which were found to be size-dependent and loading condition-selective.

  5. Nonlinear kinematics for piezoelectricity in ALEGRA-EMMA.

    Energy Technology Data Exchange (ETDEWEB)

    Mitchell, John Anthony; Fuller, Timothy Jesse

    2013-09-01

    This report develops and documents nonlinear kinematic relations needed to implement piezoelectric constitutive models in ALEGRA-EMMA [5], where calculations involving large displacements and rotations are routine. Kinematic relationships are established using Gausss law and Faradays law; this presentation on kinematics goes beyond piezoelectric materials and is applicable to all dielectric materials. The report then turns to practical details of implementing piezoelectric models in an application code where material principal axes are rarely aligned with user defined problem coordinate axes. This portion of the report is somewhat pedagogical but is necessary in order to establish documentation for the piezoelectric implementation in ALEGRA-EMMA. This involves transforming elastic, piezoelectric, and permittivity moduli from material principal axes to problem coordinate axes. The report concludes with an overview of the piezoelectric implementation in ALEGRA-EMMA and small verification examples.

  6. Vibration analysis of composite laminate plate excited by piezoelectric actuators.

    Science.gov (United States)

    Her, Shiuh-Chuan; Lin, Chi-Sheng

    2013-01-01

    Piezoelectric materials can be used as actuators for the active vibration control of smart structural systems. In this work, piezoelectric patches are surface bonded to a composite laminate plate and used as vibration actuators. A static analysis based on the piezoelectricity and elasticity is conducted to evaluate the loads induced by the piezoelectric actuators to the host structure. The loads are then employed to develop the vibration response of a simply supported laminate rectangular plate excited by piezoelectric patches subjected to time harmonic voltages. An analytical solution of the vibration response of a simply supported laminate rectangular plate under time harmonic electrical loading is obtained and compared with finite element results to validate the present approach. The effects of location and exciting frequency of piezoelectric actuators on the vibration response of the laminate plate are investigated through a parametric study. Numerical results show that modes can be selectively excited, leading to structural vibration control.

  7. Piezoelectric power converter with bi-directional power transfer

    DEFF Research Database (Denmark)

    2014-01-01

    The present invention relates to a bi-directional piezoelectric power converter com¬ prising a piezoelectric transformer. The piezoelectric transformer comprises an input electrode electrically coupled to a primary section of the piezoelectric transformer and an output electrode electrically...... coupled to an output section of the piezoelectric transformer to provide a transformer output signal. A bi-directional switching circuit is coupled between the output electrode and a DC or AC output voltage of the power converter. Forward and reverse current conducting periods of the bi......, a reverse current is conducted through the bi-directional switching circuit from the DC or AC output voltage to the output electrode to discharge the DC or AC output voltage and return power to the primary section of the piezoelectric transformer....

  8. Gelation and biocompatibility of injectable alginate-calcium phosphate gels for bone regeneration

    NARCIS (Netherlands)

    Cardoso, D.A.; Beucken, J.J.J.P van den; Both, L.L.; Bender, J.; Jansen, J.A.; Leeuwenburgh, S.C.G.

    2014-01-01

    An emerging approach toward development of injectable, self-setting, and fully biodegradable bone substitutes involves the combination of injectable hydrogel matrices with a dispersed phase consisting of nanosized calcium phosphate particles. Here, novel injectable composites for bone regeneration h

  9. Piezoelectric films for high frequency ultrasonic transducers in biomedical applications

    OpenAIRE

    Zhou, Qifa; Lau, Sienting; WU, DAWEI; Shung, K. Kirk

    2011-01-01

    Piezoelectric films have recently attracted considerable attention in the development of various sensor and actuator devices such as nonvolatile memories, tunable microwave circuits and ultrasound transducers. In this paper, an overview of the state of art in piezoelectric films for high frequency transducer applications is presented. Firstly, the basic principles of piezoelectric materials and design considerations for ultrasound transducers will be introduced. Following the review, the curr...

  10. Fronts of Stress Wave in Anisotropic Piezoelectric Media

    Institute of Scientific and Technical Information of China (English)

    刘颖; 刘凯欣; 高凌天

    2004-01-01

    The characteristic of wave fronts in anisotropic piezoelectric media is analysed by adopting the generalized characteristic theory. Analytical expressions for wave velocities and wave fronts are formulated. Apart from the ordinary characteristics, a new phenomenon, energy velocity funnel, is formed on the wave fronts of quasitransverse waves in anisotropic piezoelectric materials. A three-dimensional representation of wave fronts in anisotropic piezoelectric materials is given for a better understanding of the new phenomena.

  11. Natural frequency of beams with embedded piezoelectric sensors and actuators

    OpenAIRE

    Della, Christian N.; Shu, Dongwei

    2007-01-01

    A mathematical model is developed to study the natural frequency of beams with embedded piezoelectric sensors and actuators. The piezoelectric sensors/actuators in a non-piezoelectric matrix (host beam) are analyzed as two inhomogeneity problems by using Eshelby’s equivalent inclusion method. The natural frequency of the beam is determined from the variational principle in Rayleigh quotient form, which is expressed as functions of the elastic strain energy and dielectric energy of the piezoel...

  12. Non-Linear Piezoelectric Actuator with a Preloaded Cantilever Beam

    OpenAIRE

    Yue Wu; Jingshi Dong; Xinbo Li; Zhigang Yang; Qingping Liu

    2015-01-01

    Piezoelectric actuation is widely used for the active vibration control of smart structural systems, and corresponding research has largely focused on linear electromechanical devices. This paper investigates the design and analysis of a novel piezoelectric actuator that uses a piezoelectric cantilever beam with a loading spring to produce displacement outputs. This device has a special nonlinear property relating to converting between kinetic energy and potential energy, and it can be used t...

  13. Piezoelectric Response of Ferroelectric Ceramics Under Mechanical Stress

    Science.gov (United States)

    2015-09-17

    and piezoelectric [eg] moduli that are provided by the user for the particular material are transformed into Voight- Mandel representations [C̃g] and...problem coordinates elastic [C̃G], piezoelectric [ẽG], and permittivity [K G] moduli, using the Voight- Mandel orthogonal rotation matrices [51]. The...final step of the setup phase is transforming the global Voight- Mandel representations of the elastic [C̃G], and piezoelectric [ẽG] moduli into the

  14. Towards a two dimensional model of surface piezoelectricity

    OpenAIRE

    Monge Víllora, Oscar

    2016-01-01

    We want to understand the behaviour of flexoelectricity and surface piezoelectricity and distinguish them in order to go deep into the controversies of the filed. This motivate the construction of a model of continuum flexoelectric theory. The model proposed is a two-dimensional model that integrates the electromechanical equations that include the elastic, dielectric, piezoelectric and flexoelectric effect on a rectangular sample. As the flexoelectric and the surface piezoelectric effects ap...

  15. Fracture mechanics of piezoelectric and ferroelectric solids

    CERN Document Server

    Fang, Daining

    2013-01-01

    Fracture Mechanics of Piezoelectric and Ferroelectric Solids presents a systematic and comprehensive coverage of the fracture mechanics of piezoelectric/ferroelectric materials, which includes the theoretical analysis, numerical computations and experimental observations. The main emphasis is placed on the mechanics description of various crack problems such static, dynamic and interface fractures as well as the physical explanations for the mechanism of electrically induced fracture. The book is intended for postgraduate students, researchers and engineers in the fields of solid mechanics, applied physics, material science and mechanical engineering. Dr. Daining Fang is a professor at the School of Aerospace, Tsinghua University, China; Dr. Jinxi Liu is a professor at the Department of Engineering Mechanics, Shijiazhuang Railway Institute, China.

  16. Cantilevered probe detector with piezoelectric element

    Science.gov (United States)

    Adams, Jesse D; Sulchek, Todd A; Feigin, Stuart C

    2013-04-30

    A disclosed chemical detection system for detecting a target material, such as an explosive material, can include a cantilevered probe, a probe heater coupled to the cantilevered probe, and a piezoelectric element disposed on the cantilevered probe. The piezoelectric element can be configured as a detector and/or an actuator. Detection can include, for example, detecting a movement of the cantilevered probe or a property of the cantilevered probe. The movement or a change in the property of the cantilevered probe can occur, for example, by adsorption of the target material, desorption of the target material, reaction of the target material and/or phase change of the target material. Examples of detectable movements and properties include temperature shifts, impedance shifts, and resonant frequency shifts of the cantilevered probe. The overall chemical detection system can be incorporated, for example, into a handheld explosive material detection system.

  17. Flexible energy harvesting from hard piezoelectric beams

    Science.gov (United States)

    Delnavaz, Aidin; Voix, Jérémie

    2016-11-01

    This paper presents design, multiphysics finite element modeling and experimental validation of a new miniaturized PZT generator that integrates a bulk piezoelectric ceramic onto a flexible platform for energy harvesting from the human body pressing force. In spite of its flexibility, the mechanical structure of the proposed device is simple to fabricate and efficient for the energy conversion. The finite element model involves both mechanical and piezoelectric parts of the device coupled with the electrical circuit model. The energy harvester prototype was fabricated and tested under the low frequency periodic pressing force during 10 seconds. The experimental results show that several nano joules of electrical energy is stored in a capacitor that is quite significant given the size of the device. The finite element model is validated by observing a good agreement between experimental and simulation results. the validated model could be used for optimizing the device for energy harvesting from earcanal deformations.

  18. Energy Harvesting Using PVDF Piezoelectric Nanofabric

    Science.gov (United States)

    Shafii, Chakameh Shafii

    Energy harvesting using piezoelectric nanomaterial provides an opportunity for advancement towards self-powered electronics. The fabrication complexities and limited power output of these nano/micro generators have hindered these advancements thus far. This thesis presents a fabrication technique with electrospinning using a grounded cylinder as the collector. This method addresses the difficulties with the production and scalability of the nanogenerators. The non-aligned nanofibers are woven into a textile form onto the cylindrical drum that can be easily removed. The electrical poling and mechanical stretching induced by the electric field and the drum rotation increase the concentration of the piezoelectric beta phase in the PVDF nanofabric. The nanofabric is placed between two layers of polyethylene terephthalate (PET) that have interdigitated electrodes painted on them with silver paint. Applying continuous load onto the flexible PVDF nanofabric at 35Hz produces a peak voltage of 320 mV and maximum power of 2200 pW/(cm2) .

  19. Power Consideration in a Piezoelectric Generator

    Directory of Open Access Journals (Sweden)

    Rémi Tardiveau

    2013-01-01

    Full Text Available A piezoelectric generator converts mechanical energy into electricity and is used in energy harvesting devices. In this paper, synchronisation conditions in regard to the excitation vibration are studied. We show that a phase shift of ninety degrees between the vibration excitation and the bender’s displacement provides the maximum power from the mechanical excitation. However, the piezoelectric material is prone to power losses; hence the bender’s displacement amplitude is optimised in order to increase the amount of power which is converted into electricity. In the paper, we use active energy harvesting to control the power flow, and all the results are achieved at a frequency of 200 Hz which is well below the generator’s resonant frequency.

  20. Torque for an Inertial Piezoelectric Rotary Motor

    Directory of Open Access Journals (Sweden)

    Jichun Xing

    2013-01-01

    Full Text Available For a novel inertial piezoelectric rotary motor, the equation of the strain energy in the piezoceramic bimorph and the equations of the strain energy and the kinetic energy in the rotor are given. Based on them, the dynamic equation of the motor is obtained. Using these equations, the inertial driving torque of the motor is investigated. The results show that the impulsive driving torque changes with changing peak voltage of the excitation signal, the piezoelectric stress constant, the thickness of the piezoceramic bimorph, and the rotor radius obviously. Tests about the motor torque are completed which verifies the theory analysis here in. The results can be used to design the operating performance of the motor.