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Sample records for bioceramic si zn-modified

  1. Resorption Rate Tunable Bioceramic: Si, Zn-Modified Tricalcium Phosphate

    Energy Technology Data Exchange (ETDEWEB)

    Wei, Xiang [Iowa State Univ., Ames, IA (United States)

    2006-01-01

    ''Resorption rate tunable bioceramic: Si and Zn-modified tricalcium phosphate'' was published in Ceramic Engineering and Science Proceedings (the 29th International Conference on Advanced Ceramics and Composites - Advances in Bioceramics and Biocomposites) [5].

  2. Bacterial adherence to SiO2-based multifunctional bioceramics.

    Science.gov (United States)

    Kinnari, Teemu J; Esteban, Jaime; Gomez-Barrena, Enrique; Zamora, Nieves; Fernandez-Roblas, Ricardo; Nieto, Alejandra; Doadrio, Juan C; López-Noriega, Adolfo; Ruiz-Hernández, Eduardo; Arcos, Daniel; Vallet-Regí, María

    2009-04-01

    The bacterial adherence onto different multifunctional silica-based bioceramics has been evaluated. Staphylococcus aureus and Staphylococcus epidermidis were chosen, as they cause the majority of the implant-related infections in this field. Two SiO2 mesoporous materials (MCM-41, SBA-15), an ordered SiO2-CaO-P2O5 mesoporous glass (OMG), and a biphasic magnetic bioceramic (BMB), were incubated with S. aureus and S. epidermidis for 90 min, and subsequently sonicated to quantify the number of adhered bacteria on each material. It was found that S. aureus and S. epidermidis (10(8) CFU/mL) adhered significantly less to BMB samples when compared to MCM-41, SBA-15, or OMG. However, when the material pores accessible for bacteria in each material were taken into account, the lowest bacterial adherence was found in MCM-41, and the highest in SBA-15. The results show that bacterial adherence is higher on mesoporous bioceramics, although this higher microbial attachment is mainly due to the intergranular porosity and grain size morphology rather than to the mesoporous structure.

  3. Bioceramics of Ca phosphate and SiO{sub 2} composites

    Energy Technology Data Exchange (ETDEWEB)

    Berzina, L.; Knets, I. [Riga Technical Univ. (Latvia). Biomaterials R and D Lab.; Cimdins, R.; Vempere, D.

    2002-07-01

    The present work is devoted to the development of new bioceramics composite materials on purpose to replace damaged tissues and organ in human organism. Composite materials have been synthesized from RTU Biomaterials R and D Laboratory produced hydroxyapatite (HAp), tricalcium phosphate (TCP) and commercial SiO{sub 2} by powder technology method. The ratio of mass (HAp/SiO{sub 2} or TCP/SiO{sub 2}) in synthesised bioceramics changes from 5/95 to 40/60 with the step of 5 mass units. The structure and properties such as thermal shrinkage, water uptake, volume mass, porosity, mechanical strength etc. of crystalline phases of ceramics composites are investigated in this work depending on the ratio of raw materials concentration and sintering at temperatures 1050 C or 1100 C. The non-linear changes with serious extreme of numerical values of investigated properties of bioceramics composites were established with concentrations 15 and 35 mass % of SiO{sub 2}. It can be concluded from the structural changes in the synthesized materials. (orig.)

  4. Stimulatory effects of the ionic products from Ca-Mg-Si bioceramics on both osteogenesis and angiogenesis in vitro.

    Science.gov (United States)

    Zhai, Wanyin; Lu, Hongxu; Wu, Chengtie; Chen, Lei; Lin, Xiaoting; Naoki, Kawazoe; Chen, Guoping; Chang, Jiang

    2013-08-01

    Ideal biomaterials for bone tissue engineering should have the capability to guide the osteogenic differentiation of mesenchymal stem cells and, at the same time, to stimulate angiogenesis of endothelia cells. In this study it was found that three Ca-Mg-Si-containing bioceramics (bredigite Ca7MgSi4O16, akermanite Ca2MgSi2O7 and diopside CaMgSi2O6) had osteogenic and angiogenic potential. The effects of three silicate ceramics on the osteogenic differentiation of human bone marrow mesenchymal stem cells (hBMSCs) and the angiogenesis of human aortic endothelial cells (HAECs) were explored in comparison with β-tricalcium phosphate (β-TCP) bioceramics. The proliferation, alkaline phosphatase (ALPase) activity and bone-related gene expression (COL1, ALPase, OP, BSP and OC) of hBMSCs were significantly enhanced upon stimulation with ionic extracts of these silicate bioceramics. In addition, the results showed that extracts from the three silicate bioceramics also stimulated HAEC proliferation and in vitro angiogenesis with improved NO synthesis and angiogenic gene expression (KDR, FGFR1, ACVRL1 and NOS3). Among the three silicate ceramics bredigite showed the highest osteogenic and angiogenic potential and with the highest extract Si (possibly Si(OH)3O(-)) concentration, while diopside had the lowest osteogenic and angiogenic potential with the lowest extract Si concentration. Furthermore, it was found that the concentration of Si ions in extracts of the three silicate bioceramics was obviously higher than that of β-TCP ceramics, indicating an important role of Si ions in stimulating cell proliferation, osteogenic differentiation and angiogenesis. The results suggest that the silicate-based akermanite and bredigite ceramics might be good scaffold biomaterials for bone tissue engineering applications due to their distinctive dual functions of osteogenesis/angiogenesis stimulation.

  5. Investigation on Mechanical Properties and Microstructure of Hydroxyapatite-SiCw Composite Bioceramics

    Institute of Scientific and Technical Information of China (English)

    2005-01-01

    Hydroxyapatite-SiCw composite micropowder was synthesized using in-situ composite method,and hydroxyapatite-SiCw composite bioceramics with different content of SiCw were produced by hot pressing sintering method. The microstructures of the materials were analyzed by SEM, and the relative density, bending strength and fracture toughness of the materials were tested. The results show that the mechanical properties of composite material are best when the whisker content is 20-23.7% . The mechanical properties of the material are the best when the tensile stress acted on the composite material is parallel with the hot pressing plane, and they are the worst when the tensile stress acted on the composite material is normal to the hot pressing plane.

  6. Investigation of silicon complexes in Si-doped calcium phosphate bioceramics

    Science.gov (United States)

    Gillespie, P.; Stott, M. J.; Sayer, M.; Wu, G.

    2007-03-01

    Silicon doped calcium phosphate materials have drawn great interest as bioceramics for bone repair due to their enhanced bioactivity. However, the low level of doping in these materials, generally ˜1 wt.%, makes it difficult to determine the effects the silicon has on the structure of these materials. In this study, silicon substituted hydroxyapatite (Si-HA), silicon stabilized alpha tricalcium phosphate (Si-TCP), and a multi-phase mixture consisting of approximately 75% Si-TCP with the remainder being mainly Si-HA have been synthesized using isotopically enriched silica containing ^29Si. ^29Si magic-angle spinning nuclear magnetic resonance spectroscopy (MAS-NMR) has been used to examine the silicon complexes within these materials resulting from the substitution of SiO4^4- for PO4^3- and the required charge compensation mechanism needed to achieve this. Previous ab initio studies on these materials have investigated charge compensation mechanisms to suggest possible silicon complexes and these serve as a basis for interpreting the NMR results.

  7. Biological responses of human bone marrow mesenchymal stem cells to Sr-M-Si (M = Zn, Mg) silicate bioceramics.

    Science.gov (United States)

    Zhang, Meili; Wu, Chengtie; Lin, Kaili; Fan, Wei; Chen, Lei; Xiao, Yin; Chang, Jiang

    2012-11-01

    Strontium (Sr), Zinc (Zn), magnesium (Mg), and silicon (Si) are reported to be essential trace elements for the growth and mineralization of bone. We speculated that the combination of these bioactive elements in bioceramics may be effective to regulate the osteogenic property of bone-forming cells. In this study, two Sr-containing silicate bioceramics, Sr(2)ZnSi(2)O(7) (SZS) and Sr(2)MgSi(2)O(7) (SMS), were prepared. The biological response of human bone marrow mesenchymal stem cells (BMSCs) to the two bioceramics (in the forms of powders and dense ceramic bulks) was systematically studied. In powder form, the effect of powder extracts on the viability and alkaline phosphatase (ALP) activity of BMSCs was investigated. In ceramic disc form, both direct and indirect coculture of BMSCs with ceramic discs were used to investigate their biological response, including attachment, proliferation, ALP activity, and bone-related genes expression. Beta-tricalcium phosphate (β-TCP) and akermanite (Ca(2)MgSi(2)O(7), CMS) were used as control materials. The results showed that the Sr, Zn, and Si (or Sr, Mg, and Si)-containing ionic products from SZS and SMS powders enhanced ALP activity of BMSCs, compared to those from β-TCP. Both SZS and SMS ceramic discs supported the growth of BMSCs, and most importantly, significantly enhanced the ALP activity and bone-related genes expression of BMSCs as compared to β-TCP. The results suggest that the specific combination of bioactive ions (Sr, Zn, Si, e.g.) in bioceramics is a viable way to improve the biological performance of biomaterials, and the form of materials and surface properties were nonnegligible factors to influence cell response.

  8. Effects of h-BN addition on microstructures and mechanical properties of β-CaSiO3 bioceramics.

    Science.gov (United States)

    Pan, Ying; Yao, Dongxu; Zuo, Kaihui; Xia, Yongfeng; Yin, Jinwei; Liang, Hanqin; Zeng, Yuping

    2016-09-01

    The main purpose of this study consists in investigating the effects of h-BN addition on the sinterability of β-CaSiO3 (β-CS) bioceramics. β-CS bioceramics with different contents of h-BN were prepared at the sintering temperature ranging from 800°C to 1100°C. The results showed that h-BN can be successfully used as sintering additive by being oxidized to form low melting point B2O3 related glassy phase and enhanced the flexural strength by the formation of rod-like β-CS grains. β-CS bioceramics with 1wt% h-BN sintered at 1000°C revealed flexural strength and fracture toughness of 182.2MPa and 2.4MPam(1/2) respectively, which were much higher than that of pure β-CS bioceramics (30.2MPa, 0.53MPam(1/2)) fabricated in the same processing condition.

  9. Influence of design on bioactivity of novel CaSiO3-CaMg(SiO3)2 bioceramics: in vitro simulated body fluid test and thermodynamic simulation.

    Science.gov (United States)

    Sainz, M A; Pena, P; Serena, S; Caballero, A

    2010-07-01

    A new type of bioactive ceramic has been designed and obtained from high-temperature phase information from the wollastonite (CaSiO(3))-diopside (CaMg(SiO(3))(2)) phase equilibrium diagram. The selected composition was that corresponding to the eutectic point of the pseudobinary CaSiO(3)-CaMg(SiO(3))(2) system. The sintering behaviour, phase evolution, microstructural changes and in vitro bioactivity of CaSiO(3)-CaMg(SiO(3))(2) eutectic bioceramics were analysed by differential thermal analysis, X-ray diffraction, field emission scanning electron microscopy (FE-SEM) and image analysis. A simulation of the dissolution properties of the different materials studied, in water as well as in simulated body fluid (SBF), was also carried out by thermodynamic calculations, with the purpose of understanding the in vitro results obtained. The results demonstrate that the CaMg(SiO(3))(2) is significantly less soluble than CaSiO(3), developing an in situ porous structure (biomimetic porous bone material) with adequate biodegradation rate and stability strength when immersed in SBF. The influence of the microstructure (porosity, grain size and phase composition) on the in vitro bioactivity of the obtained bioceramics was also examined.

  10. The improved mechanical properties of β-CaSiO3 bioceramics with Si3N4 addition.

    Science.gov (United States)

    Pan, Ying; Zuo, Kaihui; Yao, Dongxu; Yin, Jinwei; Xin, Yunchuan; Xia, Yongfeng; Liang, Hanqin; Zeng, Yuping

    2015-03-01

    The motivation of this study is to investigate the effect of Si3N4 addition on the sinterability of β-CaSiO3 ceramics. β-CaSiO3 ceramics with different content of Si3N4 were prepared at the sintering temperature ranging from 1000°C to 1150°C. The results showed that Si3N4 can be successfully used as sintering additive by being oxidized to form SiO2. The β-CaSiO3 ceramics with 3wt% Si3N4 sintered at 1100°C revealed flexural strength, hardness and fracture toughness of 157.2MPa, 4.4GPa and 2.3MPam(1/2) respectively, which was much higher than that of pure β-CaSiO3 ceramics (41.1MPa, 1.0GPa, 1.1MPam(1/2)). XRD analysis and SEM observation indicated that the main phase maintained to be β-phase after sintering.

  11. Effect of MgO contents on the mechanical properties and biological performances of bioceramics in the MgO-CaO-SiO2 system.

    Science.gov (United States)

    Chen, Xianchun; Ou, Jun; Wei, Yan; Huang, Zhongbing; Kang, Yunqing; Yin, Guangfu

    2010-05-01

    The aim of this research was to investigate the effect of the chemical composition on the mechanical properties, bioactivity, and cytocompatibility in vitro of bioceramics in the MgO-CaO-SiO(2) system. Three single-phase ceramics (merwinite, akermanite and monticellite ceramics) with different MgO contents were fabricated. The mechanical properties were tested by an electronic universal machine, while the bioactivity in vitro of the ceramics was detected by investigating the bone-like apatite-formation ability in simulated body fluid (SBF), and the cytocompatibility was evaluated through osteoblast proliferation and adhesion assay. The results showed that their mechanical properties were improved from merwinite to akermanite and monticellite ceramics with the increase of MgO contents, whereas the apatite-formation ability in SBF and cell proliferation decreased. Furthermore, osteoblasts could adhere, spread and proliferate on these ceramic wafers. Finally, the elongated appearance and minor filopodia of cells on merwinite ceramic were more obvious than the other two ceramics.

  12. Effects of silica sol on the microstructure and mechanical properties of CaSiO3 bioceramics.

    Science.gov (United States)

    Pan, Ying; Yin, Jinwei; Yao, Dongxu; Zuo, Kaihui; Xia, Yongfeng; Liang, Hanqin; Zeng, YuPing

    2016-07-01

    CaSiO3 ceramics were fabricated with silica sol addition by pressureless sintering. The effects of silica sol on phase composition, microstructure and mechanical properties of CaSiO3 ceramics were investigated. The silica sol additive was found to be effective in speeding up pore elimination, improving the grain growth, decreasing the sintering temperature and shortening the sintering time. When the amount of SiO2 was 5wt%, a flexural strength of 186.2MPa was achieved with an open porosity of 3.9%. The main crystal phase was β-CaSiO3 below sintering temperature of 1150°C.

  13. Bioceramics of calcium orthophosphates.

    Science.gov (United States)

    Dorozhkin, Sergey V

    2010-03-01

    A strong interest in use of ceramics for biomedical applications appeared in the late 1960's. Used initially as alternatives to metals in order to increase a biocompatibility of implants, bioceramics have become a diverse class of biomaterials, presently including three basic types: relatively bioinert ceramics, bioactive (or surface reactive) and bioresorbable ones. Furthermore, any type of bioceramics could be porous to provide tissue ingrowth. This review is devoted to bioceramics prepared from calcium orthophosphates, which belong to the categories of bioresorbable and bioactive compounds. During the past 30-40 years, there have been a number of major advances in this field. Namely, after the initial work on development of bioceramics that was tolerated in the physiological environment, emphasis was shifted towards the use of bioceramics that interacted with bones by forming a direct chemical bond. By the structural and compositional control, it became possible to choose whether the bioceramics of calcium orthophosphates was biologically stable once incorporated within the skeletal structure or whether it was resorbed over time. At the turn of the millennium, a new concept of calcium orthophosphate bioceramics, which is able to regenerate bone tissues, has been developed. Current biomedical applications of calcium orthophosphate bioceramics include replacements for hips, knees, teeth, tendons and ligaments, as well as repair for periodontal disease, maxillofacial reconstruction, augmentation and stabilization of the jawbone, spinal fusion and bone fillers after tumor surgery. Potential future applications of calcium orthophosphate bioceramics will include drug-delivery systems, as well as they will become effective carriers of growth factors, bioactive peptides and/or various types of cells for tissue engineering purposes.

  14. Si-modified BHA bioceramics as a drug delivery system: Effect of modification method on structure and Rifampicin release

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    Olena Sych

    2015-09-01

    Full Text Available The work is devoted to the investigation of two different methods for introduction of silicon into ceramics, based on biogenic hydroxyapatite (BHA, on the structure and properties. Thus, porous samples of Si-modified BHA-based ceramics containing 2 or 5 wt.% Si were prepared by using two different precursors, i.e. polymethylsiloxane polyhydrate and fine silica (Aerosil® 200 powder. After the modification with silicon a marked change in the structure of material was observed. The use of Aerosil® 200 permits preparation of a more uniform structure as compared to that obtained by using polymethylsiloxane polyhydrate. However, the latter promotes an increase in both the porosity of samples (from 43 to 62.3% and their solubility in saline (from 0.18 to 1.20 wt.%/day as compared to the results obtained after the modification with Aerosil® 200, where maximal porosity and solubility were 48.5% and 0.23 wt.%/day, respectively. At the same time, the modification of hydroxyapatite ceramics with silicon using silica makes it possible to prolong release of a drug (e.g. Rifampicin out of sample pores for the first 24 h as compared to the ceramics modified with polymethylsiloxane polyhydrate.

  15. BONES WITH BIOCERAMICS

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    Wijianto Wijianto

    2017-01-01

    Full Text Available This paper discuss about ceramics in application as bone implant. Bioceramics for instance Hydroxyapatite, usually is abbreviated with HA or HAp, is a mineral that is very good physical properties as bone replacement in human body. To produce Hydroxyapatite, coating process is used which have good potential as they can exploit the biocompatible and bone bonding properties of the ceramic. There are many advantages and disadvantages of bioceramics as bone implant. Advantages of hydroxyapatite as bone implant are rapidly integrated into the human body, and is most interesting property that will bond to bone forming indistinguishable unions. On contrary, disadvantages of hydroxyapatite as bone implant are poor mechanical properties (in particular fatigue properties mean that hydroxyapatite cannot be used in bulk form for load bearing applications such as orthopaedics and poor adhesion between the calcium phosphate coating and the material implant will occur.

  16. An introduction to bioceramics

    CERN Document Server

    Hench, Larry L

    1993-01-01

    Ceramic materials that are specially developed for use as medical and dental implants are termed bioceramics. They include alumina and zirconia, bioactive glasses, glass-ceramics, coatings and composites, hydroxyapatite and resorbable calcium phosphates, and radiotherapy glasses. This is the first textbook in a field which is growing rapidly in clinical applications including orthopedics, otolaryngology, maxillo-facial and plastic surgery, oral surgery, periodontology, and tumor therapy. Fourteen chapters, written by world experts, describe the processing, compositions, properties, surface che

  17. Bioceramics in ophthalmology.

    Science.gov (United States)

    Baino, Francesco; Vitale-Brovarone, Chiara

    2014-08-01

    The benefits of ceramics in biomedical applications have been universally appreciated as they exhibit an extraordinarily broad set of physico-chemical, mechanical and biological properties which can be properly tailored by acting on their composition, porosity and surface texture to increase their versatility and suitability for targeted healthcare applications. Bioceramics have traditionally been used for the repair of hard tissues, such as bone and teeth, mainly due to their suitable strength for load-bearing applications, wear resistance (especially alumina, zirconia and composites thereof) and, in some cases, bone-bonding ability (calcium orthophosphates and bioactive glasses). Bioceramics have been also applied in other medical areas, like ophthalmic surgery; although their use in such a context has been scientifically documented since the late 1700s, the potential and importance of ceramic ocular implants still seem to be underestimated and an exhaustive, critical assessment is currently lacking in the relevant literature. The present review aims to fill this gap by giving a comprehensive picture of the ceramic-based materials and implants that are currently used in ophthalmology and pointing out the strengths and weaknesses of the existing devices. A prospect for future research is also provided, highlighting the potential of new, smart bioceramics able to carry specific added values which could have a significant impact on the treatment of ocular diseases.

  18. Bioceramics for implant coatings

    Directory of Open Access Journals (Sweden)

    Allison A Campbell

    2003-11-01

    Early research in this field focused on understanding the biomechanical properties of metal implants, but recent work has turned toward improving the biological properties of these devices. This has led to the introduction of calcium phosphate (CaP bioceramics as a bioactive interface between the bulk metal impart and the surrounding tissue. The first CaP coatings were produced via vapor phase processes, but more recently solution-based and biomimetic methods have emerged. While each approach has its own intrinsic materials and biological properties, in general CaP coatings promise to improve implant biocompatibility and ultimately implant longevity.

  19. Bioceramic Nanofibres by Electrospinning

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    Rajkamal Balu

    2014-08-01

    Full Text Available Nanoscale three-dimensional (3D scaffolds offer great promise for improved tissue integration and regeneration by their physical and chemical property enhancements. Electrospinning is a versatile bottom-up technique for producing porous 3D nanofibrous scaffolds that could closely mimic the structure of extracellular matrix. Much work has been committed to the development of this process through the years, and the resultant nanostructures have been subjugated to a wide range of applications in the field of bioengineering. In particular, the application of ceramic nanofibres in hard tissue engineering, such as dental and bone regeneration, is of increased research interest. This mini-review provides a brief overview of the bioceramic nanofibre scaffolds fabricated by electrospinning and highlights some of the significant process developments over recent years with their probable future trends and potential applications as biomedical implants.

  20. The stimulation of proliferation and differentiation of periodontal ligament cells by the ionic products from Ca7Si2P2O16 bioceramics.

    Science.gov (United States)

    Zhou, Yinghong; Wu, Chengtie; Xiao, Yin

    2012-07-01

    The ultimate goal of periodontal tissue engineering is to produce predictable regeneration of alveolar bone, root cementum, and periodontal ligament, which are lost as a result of periodontal diseases. To achieve this goal, it is of great importance to develop novel bioactive materials which could stimulate the proliferation, differentiation and osteogenic/cementogenic gene expression of periodontal ligament cells (PDLCs) for periodontal regeneration. In this study, we synthesized novel Ca(7)Si(2)P(2)O(16) ceramic powders for the first time by the sol-gel method and investigated the biological performance of PDLCs after exposure to different concentrations of Ca(7)Si(2)P(2)O(16) extracts. The original extracts were prepared at 200 mg ml(-1) and further diluted with serum-free cell culture medium to obtain a series of diluted extracts (100, 50, 25, 12.5 and 6.25 mg ml(-1)). Proliferation, alkaline phosphatase (ALP) activity, Ca deposition, and osteogenesis/cementogenesis-related gene expression (ALP, Col I, Runx2 and CEMP1) were assayed for PDLCs on days 7 and 14. The results showed that the ionic products from Ca(7)Si(2)P(2)O(16) powders significantly stimulated the proliferation, ALP activity, Ca deposition and osteogenesis/cementogenesis-related gene expression of PDLCs. In addition, it was found that Ca(7)Si(2)P(2)O(16) powders had excellent apatite-mineralization ability in simulated body fluids. This study demonstrated that Ca(7)Si(2)P(2)O(16) powders with such a specific composition possess the ability to stimulate the PDLC proliferation and osteoblast/cemenoblast-like cell differentiation, indicating that they are a promising bioactive material for periodontal tissue regeneration application.

  1. Nanostructured bioceramics for maxillofacial applications.

    Science.gov (United States)

    Adamopoulos, Othon; Papadopoulos, Triantafillos

    2007-08-01

    Biomaterials science and technology have been expanding tremendously the recent years. The results of this evolution are obvious in maxillofacial applications especially with the contemporary development of Nanotechnology. Among biomaterials, bioceramics possess a specific field due to various interactions with the biological tissues. The combination of bioceramics and nanotechnology has resulted in enhanced skeletal interactions in maxillofacial applications. Nanotechnology secures better mechanical properties and more effective biological interactions with jaws. The main production methods for the synthesis of nanostructured materials include plasma arcing, chemical vapour deposition, sol-gel and precipitation. The bioceramics in Dentistry comprise inert, bioactive, resorbable and composite systems. The purpose of the present article is to describe the available nanotechnology methods and how these could be addressed to synthesise maxillofacial bioceramics with advanced properties for better biological applications. Additionally, it describes specific clinical applications in maxillofacial surgery of these biomaterials--either by themselves or in combination with others--that can be promising candidates for bone tissue engineering. Such applications include replacement of lost teeth, filling of jaws defects or reconstruction of mandible and temporomandibular joint.

  2. Surface modification of bioceramics

    Science.gov (United States)

    Monkawa, Akira

    Hydroxyapatite [Ca10(PO4)6(OH)2, HAp] is a major inorganic component of bone and teeth tissues and has the excellent biocompatibility and high osteoconductivity. The interactions between HAp and protein or cell have been studied. The HAp related bioceramics such as bone substitute, coating substance of metal implants, inorganic-polymer composites, and cell culture. We described two methods; (1) surface modification of HAp using organosilane; (2) fabrication of HAp ultra-thin layer on gold surface for protein adsorption analyzed with QCM-D technique. The interfacial interaction between collagen and HAp in a nano-region was controlled by depositing the organosilane of n-octadecyltrimethoxysilane (ODS: -CH3) or aminopropyltriethoxysilane (APTS: -NH2) with a chemical vapor deposition method. The morphologies of collagen adsorbed on the surfaces of HAp and HAp deposited with APTS were similar, however that of the surface with ODS was apparently different, due to the hydrophobic interaction between the organic head group of -CH3 and residual groups of collagen. We present a method for coating gold quartz crystal microbalance with dissipation (QCM-D) sensor with ultra-thin layer of hydroxyapatite nanocrystals evenly covering and tightly bound to the surface. The hydroxyapatite sensor operated in liquid with high stability and sensitivity. The in-situ adsorption mechanism and conformational change of fibrinogen on gold, titanium and hydroxyapatite surfaces were investigated by QCM-D technique and Fourier-transform infrared spectroscopy. The study indicates that the hydroxyapatite sensor is applicable for qualitative and conformational analysis of protein adsorption.

  3. Silicon Nitride Bioceramics Induce Chemically Driven Lysis in Porphyromonas gingivalis.

    Science.gov (United States)

    Pezzotti, Giuseppe; Bock, Ryan M; McEntire, Bryan J; Jones, Erin; Boffelli, Marco; Zhu, Wenliang; Baggio, Greta; Boschetto, Francesco; Puppulin, Leonardo; Adachi, Tetsuya; Yamamoto, Toshiro; Kanamura, Narisato; Marunaka, Yoshinori; Bal, B Sonny

    2016-03-29

    Organisms of Gram-negative phylum bacteroidetes, Porphyromonas gingivalis, underwent lysis on polished surfaces of silicon nitride (Si3N4) bioceramics. The antibacterial activity of Si3N4 was mainly the result of chemically driven principles. The lytic activity, although not osmotic in nature, was related to the peculiar pH-dependent surface chemistry of Si3N4. A buffering effect via the formation of ammonium ions (NH4(+)) (and their modifications) was experimentally observed by pH microscopy. Lysis was confirmed by conventional fluorescence spectroscopy, and the bacteria's metabolism was traced with the aid of in situ Raman microprobe spectroscopy. This latter technique revealed the formation of peroxynitrite within the bacterium itself. Degradation of the bacteria's nucleic acid, drastic reduction in phenilalanine, and reduction of lipid concentration were observed due to short-term exposure (6 days) to Si3N4. Altering the surface chemistry of Si3N4 by either chemical etching or thermal oxidation influenced peroxynitrite formation and affected bacteria metabolism in different ways. Exploiting the peculiar surface chemistry of Si3N4 bioceramics could be helpful in counteracting Porphyromonas gingivalis in an alkaline pH environment.

  4. Calcium Orthophosphate-Based Bioceramics

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    Sergey V. Dorozhkin

    2013-09-01

    Full Text Available Various types of grafts have been traditionally used to restore damaged bones. In the late 1960s, a strong interest was raised in studying ceramics as potential bone grafts due to their biomechanical properties. A bit later, such synthetic biomaterials were called bioceramics. In principle, bioceramics can be prepared from diverse materials but this review is limited to calcium orthophosphate-based formulations only, which possess the specific advantages due to the chemical similarity to mammalian bones and teeth. During the past 40 years, there have been a number of important achievements in this field. Namely, after the initial development of bioceramics that was just tolerated in the physiological environment, an emphasis was shifted towards the formulations able to form direct chemical bonds with the adjacent bones. Afterwards, by the structural and compositional controls, it became possible to choose whether the calcium orthophosphate-based implants remain biologically stable once incorporated into the skeletal structure or whether they were resorbed over time. At the turn of the millennium, a new concept of regenerative bioceramics was developed and such formulations became an integrated part of the tissue engineering approach. Now calcium orthophosphate scaffolds are designed to induce bone formation and vascularization. These scaffolds are often porous and harbor different biomolecules and/or cells. Therefore, current biomedical applications of calcium orthophosphate bioceramics include bone augmentations, artificial bone grafts, maxillofacial reconstruction, spinal fusion, periodontal disease repairs and bone fillers after tumor surgery. Perspective future applications comprise drug delivery and tissue engineering purposes because calcium orthophosphates appear to be promising carriers of growth factors, bioactive peptides and various types of cells.

  5. Bioceramic in dental implants: A review

    OpenAIRE

    Gaurav P Jayaswal; Dange, S. P.; Khalikar, A. N.

    2010-01-01

    Biomaterials are non-drug substance suitable for inclusion in system which augment or replace the function of bodily tissue or organ. Orthopedic and dental applications represent approximately 55% of the total biomaterials market. Changes in biologic responses and device design have been the direct result of advances in material science. Bioceramics fulfill a unique function as biomedical materials. Bioceramics are non-toxic and bioinert, bioactive or bioresorbable. Bioceramics continue to be...

  6. A review of protein adsorption on bioceramics

    OpenAIRE

    Wang, Kefeng; Zhou, Changchun; Hong, Youliang; Zhang, Xingdong

    2012-01-01

    Bioceramics, because of its excellent biocompatible and mechanical properties, has always been considered as the most promising materials for hard tissue repair. It is well know that an appropriate cellular response to bioceramics surfaces is essential for tissue regeneration and integration. As the in vivo implants, the implanted bioceramics are immediately coated with proteins from blood and body fluids, and it is through this coated layer that cells sense and respond to foreign implants. H...

  7. 3D Printing Bioceramic Porous Scaffolds with Good Mechanical Property and Cell Affinity.

    Directory of Open Access Journals (Sweden)

    Chih-Hao Chang

    Full Text Available Artificial bone grafting is widely used in current orthopedic surgery for bone defect problems. Unfortunately, surgeons remain unsatisfied with the current commercially available products. One of the major complaints is that these products cannot provide sufficient mechanical strength to support the human skeletal structure. In this study, we aimed to develop a bone scaffold with better mechanical property and good cell affinity by 3D printing (3DP techniques. A self-developed 3D printer with laser-aided gelling (LAG process was used to fabricate bioceramic scaffolds with inter-porous structures. To improve the mechanical property of the bioceramic parts after heating, CaCO3 was added to the silica ceramic slurry. CaCO3 was blended into a homogenous SiO2-sol dispersion at weight ratios varying from 0/100 to 5/95 to 9/91 (w/w. Bi-component CaCO3/SiO2-sol was prepared as a biocomposite for the 3DP scaffold. The well-mixed biocomposite was used to fabricate the bioceramic green part using the LAG method. The varied scaffolds were sintered at different temperatures ranging from 900 to 1500°C, and the mechanical property was subsequently analyzed. The scaffolds showed good property with the composite ratio of 5:95 CaCO3:SiO2 at a sintering temperature of 1300°C. The compressive strength was 47 MPa, and the porosity was 34%. The topography of the sintered 3DP bioceramic scaffold was examined by SEM, EDS and XRD. The silica bioceramic presented no cytotoxicity and good MG-63 osteoblast-like cell affinity, demonstrating good biocompatibility. Therefore, the new silica biocomposite is viable for fabricating 3DP bone bioceramics with improved mechanical property and good cell affinity.

  8. 3D Printing Bioceramic Porous Scaffolds with Good Mechanical Property and Cell Affinity.

    Science.gov (United States)

    Chang, Chih-Hao; Lin, Chih-Yang; Liu, Fwu-Hsing; Chen, Mark Hung-Chih; Lin, Chun-Pin; Ho, Hong-Nerng; Liao, Yunn-Shiuan

    2015-01-01

    Artificial bone grafting is widely used in current orthopedic surgery for bone defect problems. Unfortunately, surgeons remain unsatisfied with the current commercially available products. One of the major complaints is that these products cannot provide sufficient mechanical strength to support the human skeletal structure. In this study, we aimed to develop a bone scaffold with better mechanical property and good cell affinity by 3D printing (3DP) techniques. A self-developed 3D printer with laser-aided gelling (LAG) process was used to fabricate bioceramic scaffolds with inter-porous structures. To improve the mechanical property of the bioceramic parts after heating, CaCO3 was added to the silica ceramic slurry. CaCO3 was blended into a homogenous SiO2-sol dispersion at weight ratios varying from 0/100 to 5/95 to 9/91 (w/w). Bi-component CaCO3/SiO2-sol was prepared as a biocomposite for the 3DP scaffold. The well-mixed biocomposite was used to fabricate the bioceramic green part using the LAG method. The varied scaffolds were sintered at different temperatures ranging from 900 to 1500°C, and the mechanical property was subsequently analyzed. The scaffolds showed good property with the composite ratio of 5:95 CaCO3:SiO2 at a sintering temperature of 1300°C. The compressive strength was 47 MPa, and the porosity was 34%. The topography of the sintered 3DP bioceramic scaffold was examined by SEM, EDS and XRD. The silica bioceramic presented no cytotoxicity and good MG-63 osteoblast-like cell affinity, demonstrating good biocompatibility. Therefore, the new silica biocomposite is viable for fabricating 3DP bone bioceramics with improved mechanical property and good cell affinity.

  9. 3D Printing Bioceramic Porous Scaffolds with Good Mechanical Property and Cell Affinity

    Science.gov (United States)

    Chang, Chih-Hao; Lin, Chih-Yang; Liu, Fwu-Hsing; Chen, Mark Hung-Chih; Lin, Chun-Pin; Ho, Hong-Nerng; Liao, Yunn-Shiuan

    2015-01-01

    Artificial bone grafting is widely used in current orthopedic surgery for bone defect problems. Unfortunately, surgeons remain unsatisfied with the current commercially available products. One of the major complaints is that these products cannot provide sufficient mechanical strength to support the human skeletal structure. In this study, we aimed to develop a bone scaffold with better mechanical property and good cell affinity by 3D printing (3DP) techniques. A self-developed 3D printer with laser-aided gelling (LAG) process was used to fabricate bioceramic scaffolds with inter-porous structures. To improve the mechanical property of the bioceramic parts after heating, CaCO3 was added to the silica ceramic slurry. CaCO3 was blended into a homogenous SiO2-sol dispersion at weight ratios varying from 0/100 to 5/95 to 9/91 (w/w). Bi-component CaCO3/SiO2-sol was prepared as a biocomposite for the 3DP scaffold. The well-mixed biocomposite was used to fabricate the bioceramic green part using the LAG method. The varied scaffolds were sintered at different temperatures ranging from 900 to 1500°C, and the mechanical property was subsequently analyzed. The scaffolds showed good property with the composite ratio of 5:95 CaCO3:SiO2 at a sintering temperature of 1300°C. The compressive strength was 47 MPa, and the porosity was 34%. The topography of the sintered 3DP bioceramic scaffold was examined by SEM, EDS and XRD. The silica bioceramic presented no cytotoxicity and good MG-63 osteoblast-like cell affinity, demonstrating good biocompatibility. Therefore, the new silica biocomposite is viable for fabricating 3DP bone bioceramics with improved mechanical property and good cell affinity. PMID:26618362

  10. Surface characterization of silicate bioceramics.

    Science.gov (United States)

    Cerruti, Marta

    2012-03-28

    The success of an implanted prosthetic material is determined by the early events occurring at the interface between the material and the body. These events depend on many surface properties, with the main ones including the surface's composition, porosity, roughness, topography, charge, functional groups and exposed area. This review will portray how our understanding of the surface reactivity of silicate bioceramics has emerged and evolved in the past four decades, owing to the adoption of many complementary surface characterization tools. The review is organized in sections dedicated to a specific surface property, each describing how the property influences the body's response to the material, and the tools that have been adopted to analyse it. The final section introduces the techniques that have yet to be applied extensively to silicate bioceramics, and the information that they could provide.

  11. Surface toughness of silicon nitride bioceramics: I, Raman spectroscopy-assisted micromechanics.

    Science.gov (United States)

    Pezzotti, Giuseppe; Enomoto, Yuto; Zhu, Wenliang; Boffelli, Marco; Marin, Elia; McEntire, Bryan J

    2016-02-01

    Indentation micro-fracture is revisited as a tool for evaluating the surface toughness of silicon nitride (Si3N4) bioceramics for artificial joint applications. Despite being unique and practical from an experimental perspective, a quantitative assessment of surface fracture toughness using this method is challenging. An improved method has been developed, consisting of coupling indentation with confocal (spatially resolved) Raman piezo-spectroscopy. Empowered by the Raman microprobe, the indentation micro-fracture method was found to be capable of providing reliable surface toughness measurements in silicon nitride biomaterials. In designing the microstructures of bioceramic bearing couples for improved tribological performance, surface toughness must be considered as a fundamentally different and distinct parameter from bulk toughness. The coupling of indention crack opening displacements (COD) with local stress field assessments by spectroscopy paves the way to reliably compare the structural properties of bioceramics and to quantitatively monitor their evolution during environmental exposure.

  12. A review of protein adsorption on bioceramics.

    Science.gov (United States)

    Wang, Kefeng; Zhou, Changchun; Hong, Youliang; Zhang, Xingdong

    2012-06-06

    Bioceramics, because of its excellent biocompatible and mechanical properties, has always been considered as the most promising materials for hard tissue repair. It is well know that an appropriate cellular response to bioceramics surfaces is essential for tissue regeneration and integration. As the in vivo implants, the implanted bioceramics are immediately coated with proteins from blood and body fluids, and it is through this coated layer that cells sense and respond to foreign implants. Hence, the adsorption of proteins is critical within the sequence of biological activities. However, the biological mechanisms of the interactions of bioceramics and proteins are still not well understood. In this review, we will recapitulate the recent studies on the bioceramic-protein interactions.

  13. Synthesis and evaluation of bioceramics for orthopedics and tissue culture applications

    Science.gov (United States)

    Demirkiran, Hande

    Hydroxyapatite is the most well known phosphate in the biologically active phosphate ceramic family by virtue of its similarity to natural bone mineral. Among all bioglass compositions BioglassRTM45S5 is one of the most bioactive glasses. This study initially started by adding different amounts (1, 2.5, 5, 10, and 25 wt.%) of BioglassRTM45S5 to synthetic hydroxyapatite in order to improve the bioactivity of these bioceramics. The chemistries formed by sintering and their effect on different material properties including bioactivity were identified by using various techniques, such as powder and thin film x-ray diffraction, scanning electron microscopy coupled with energy dispersive X-ray spectroscopy, X-ray absorption near edge spectroscopy, compression test, and nano indentation. All the results demonstrated that 10 and 25 wt.% BioglassRTM45S5 addition to hydroxyapatite and sintering at 1200°C for 4 hours yield new compositions with main Ca 5(PO4)2SiO4 and Na3Ca 6(PO4)5 crystalline phases dispersed in silicate glassy matrices, respectively. In addition, in vitro bioactivity tests such as bone like apatite formation in simulated body fluid and bone marrow stromal cell culture have shown that the crystalline and amorphous phases have an important role on improving bioactivity of these bioceramic compositions. Besides, compression test and nano indentation has given important information on compression strength and nano structure properties of these newly composed bioceramic materials and the bone like apatite layers formed on them, respectively. Finally, the effect of silicate addition on both formation and bioactivity of Na3Ca6(PO4)5 bioceramics were shown. These findings and different techniques used assisted to develop a phenomenological approach to demonstrate how the novel bioceramic compositions were composed and aid improving bioactivity of known bioceramic materials.

  14. The use of bioceramics in endodontics - literature review

    OpenAIRE

    JITARU, STEFAN; HODISAN, IOANA; TIMIS, LUCIA; LUCIAN, ANAMARIA; BUD, MARIUS

    2016-01-01

    Background and aim Bioceramics are ceramic compounds obtained both in situ and in vivo, by various chemical processes. Bioceramics exhibit excellent biocompatibility due to their similarity with biological materials, like hydroxyapatite. Bioceramics and multi-substituted hydroxyapatite or similar compounds have the ability to induce a regenerative response in the organism. The aim of this paper is to make a literature review on the main bioceramic materials currently used in endodontics and o...

  15. 3D-printed silicate porous bioceramics using a non-sacrificial preceramic polymer binder.

    Science.gov (United States)

    Zocca, A; Elsayed, H; Bernardo, E; Gomes, C M; Lopez-Heredia, M A; Knabe, C; Colombo, P; Günster, J

    2015-05-22

    Silicate bioceramics possess an excellent bioactivity; however, shaping them into complex geometries is still challenging. Therefore, this paper aims to present a new strategy for the shaping of a bioglass-ceramic with controlled geometry and properties starting from a glass powder combined with a preceramic polymer, i.e. a silicon resin, and reactive fillers. The powder-based three-dimensional (3D)-printing of wollastonite (CaSiO3)-based silicate bioceramic parts was demonstrated in this work. The resin plays a dual role, as it not only acts as a non-sacrificial binder for the filler powders in the printing process but it also reacts with the fillers to generate the desired bioceramic phases. The mechanical and physical properties, i.e. ball-on-three-balls test, density, porosity and morphology, were evaluated in 3D-printed discs. These samples possessed a total porosity around 64 vol% and a biaxial flexural strength around 6 MPa. The raw materials used in this work also enabled the 3D-printing of scaffolds possessing a designed multi-scale porosity, suitable bioceramic phase assemblage and a compressive strength of 1 MPa (for cylindrical scaffolds with total porosity ~80 vol%). Solubility in TRIS/HCl and in vitro assays, i.e. viability, cytotoxicity and apoptosis assays, were also performed. In vitro tests indicated good cell viability and no cytotoxicity effect on the cells.

  16. A comparative study on the synthesis mechanism, bioactivity and mechanical properties of three silicate bioceramics.

    Science.gov (United States)

    Najafinezhad, Aliakbar; Abdellahi, Majid; Ghayour, Hamid; Soheily, Ali; Chami, Akbar; Khandan, Amirsalar

    2017-03-01

    In the present study three akermanite (Ca2MgSi2O7), diopside (CaMgSi2O6) and baghdadite (Ca3ZrSi2O9) applicable bioceramics were synthesized via a sol-gel based method. The combination of sol-gel method and the raw materials used in this study presents a new route for the synthesis of the mentioned bioceramics. By the use of thermal analysis, the mechanisms occurred during the synthesis of these bioceramics were investigated. The differences in the structural density and their relation with the degradation rate and mechanical properties of all three ceramics were studied. In vitro bioactivity and apatite formation mechanisms of the samples soaked in the simulated body fluid were considered. The results showed that baghdadite as a Zr-containing material has a more dense structure in comparison with the other ceramics, which leads to a lower degradation rate and also lower bioactivity. There were also main differences between akermanite and diopside as Mg-containing ceramics. Diopside showed a structure with lower porosity content compared to the akermanite samples which resulted in the lower degradation rate and higher compressive strength.

  17. Akermanite bioceramics promote osteogenesis, angiogenesis and suppress osteoclastogenesis for osteoporotic bone regeneration.

    Science.gov (United States)

    Xia, Lunguo; Yin, Zhilan; Mao, Lixia; Wang, Xiuhui; Liu, Jiaqiang; Jiang, Xinquan; Zhang, Zhiyuan; Lin, Kaili; Chang, Jiang; Fang, Bing

    2016-02-25

    It is a big challenge for bone healing under osteoporotic pathological condition with impaired angiogenesis, osteogenesis and remodeling. In the present study, the effect of Ca, Mg, Si containing akermanite bioceramics (Ca2MgSi2O7) extract on cell proliferation, osteogenic differentiation and angiogenic factor expression of BMSCs derived from ovariectomized rats (BMSCs-OVX) as well as the expression of osteoclastogenic factors was evaluated. The results showed that akermanite could enhance cell proliferation, ALP activity, expression of Runx2, BMP-2, BSP, OPN, OCN, OPG and angiogenic factors including VEGF and ANG-1. Meanwhile, akermanite could repress expression of osteoclastogenic factors including RANKL and TNF-α. Moreover, akermanite could activate ERK, P38, AKT and STAT3 signaling pathways, while crosstalk among these signaling pathways was evident. More importantly, the effect of akermanite extract on RANKL-induced osteoclastogenesis was evaluated by TRAP staining and real-time PCR assay. The results showed that akermanite could suppress osteoclast formation and expression of TRAP, cathepsin K and NFATc1. The in vivo experiments revealed that akermanite bioceramics dramatically stimulated osteogenesis and angiogenesis in an OVX rat critical-sized calvarial defect model. All these results suggest that akermanite bioceramics with the effects of Mg and Si ions on osteogenesis, angiogenesis and osteoclastogenesis are promising biomaterials for osteoporotic bone regeneration.

  18. Development of calcium phosphate based bioceramics

    Indian Academy of Sciences (India)

    Amit Sinha; A Ingle; K R Munim; S N Vaidya; B P Sharma; A N Bhisey

    2001-12-01

    Two bioceramics (Ca–P–O glass and A–W glass ceramic) were produced using conventional methods of ceramic technology. X-ray powder diffraction patterns were used for identifying the phases and 3-point bend test was carried out for the determination of fracture strength of the bioceramics. Biocompatibility of both ceramics was evaluated using animal model experiments. Histological studies showed that A–W glass ceramic implanted in the tibia of rat formed an intimate contact with newly grown bone and provided enough strength to the bone to bear the animal weight. Implants made of Ca–P–O glass was almost fully resorbed and was replaced by new bone. The implants made of both the bioceramics were biocompatible and did not exhibit any kind of adverse effect to the surrounding tissues.

  19. Bioceramic Coatings for Orthopaedic Implants

    Energy Technology Data Exchange (ETDEWEB)

    Campbell, Allison A.

    2003-11-02

    During the past century, man-made materials and devices have been developed to the point at which they have been used successfully to replace and/or restore function to diseased or damaged tissues. In the field of orthopaedics, the use of metal implants has significantly improved the quality of life for countless individuals. Critical factors for implant success include proper design, material selection, and biocompatibility. While early research focused on the understanding biomechanical properties of the metal device, recent work has turned toward improving the biological properties of these devices. This has lead to the introduction of calcium phosphate (CaP) bioceramics as a bioactive interface between the bulk metal impart and the surrounding tissue. The first calcium phosphate coatings where produced via vapor phase routes but more recently, there has been the emergence of solution based and biomimetic methods. While each approach has its own intrinsic materials and biological properties, in general CaP coatings have the promise to improve implant biocompatibility and ultimately implant longevity.

  20. Engineering bioceramic microstructure for customized drug delivery

    Science.gov (United States)

    Pacheco Gomez, Hernando Jose

    One of the most efficient approaches to treat cancer and infection is to use biomaterials as a drug delivery system (DDS). The goal is for the material to provide a sustained release of therapeutic drug dose locally to target the ill tissue without affecting other organs. Silica Calcium Phosphate nano composite (SCPC) is a drug delivery platform that successfully demonstrated the ability to bind and release several therapeutics including antibiotics, anticancer drugs, and growth factors. The aim of the present work is to analyze the role of SCPC microstructure on drug binding and release kinetics. The main crystalline phases of SCPC are alpha-cristobalite (SiO2, Cris) and beta-rhenanite (NaCaPO4, Rhe); therefore, these two phases were prepared and characterized separately. Structural and compositional features of Cris, Rhe and SCPC bioceramics demonstrated a significant influence on the loading capacity and release kinetics profile of Vancomycin (Vanc) and Cisplatin (Cis). Fourier Transform Infrared (FTIR) spectroscopy analyses demonstrated that the P-O functional group in Rhe and SCPC has high affinity to the (C=O and N-H) of Vanc and (N-H and O-H) of Cis. By contrast, a weak chemical interaction between the Si-O functional group in Cris and SCPC and the two drugs was observed. Vanc loading per unit surface area increased in the order 8.00 microg Vanc/m2 for Rhe > 4.49 microg Vanc /m2 for SCPC>3.01 microg Vanc /m2 for Cris (ptherapeutic effects of the SCPC-Cis hybrid were evaluated using a rat model of hepatocellular carcinoma (HCC). Animals were treated by either systemic cisplatin injection (sCis), or with SCPC-Cis hybrid placed adjacent (ADJ) to, or within (IT), the tumor. Five days after implantation 50-55% of the total cisplatin loaded was released from the SCPC-Cis hybrids resulting in an approximately 50% decrease in tumor volume compared to sCis treatment. Severe side effects were observed in animals treated with sCis including rapid weight loss and

  1. Bioceramics: from bone regeneration to cancer nanomedicine.

    Science.gov (United States)

    Vallet-Regí, María; Ruiz-Hernández, Eduardo

    2011-11-23

    Research on biomaterials has been growing in the last few years due to the clinical needs in organs and tissues replacement and regeneration. In addition, cancer nanomedicine has recently appeared as an effective means to combine nanotechnology developments towards a clinical application. Ceramic materials are suitable candidates to be used in the manufacturing of bone-like scaffolds. Bioceramic materials may also be designed to deliver biologically active substances aimed at repairing, maintaining, restoring or improving the function of organs and tissues in the organism. Several materials such as calcium phosphates, glasses and glass ceramics able to load and subsequently release in a controlled fashion drugs, hormones, growth factors, peptides or nucleic acids have been developed. In particular, to prevent post surgical infections bioceramics may be surface modified and loaded with certain antibiotics, thus preventing the formation of bacterial biofilms. Remarkably, mesoporous bioactive glasses have shown excellent characteristics as drug carrying bone regeneration materials. These bioceramics are not only osteoconductive and osteoproductive, but also osteoinductive, and have therefore been proposed as ideal components for the fabrication of scaffolds for bone tissue engineering. A recent promising development of bioceramic materials is related to the design of magnetic mediators against tumors. Magnetic composites are suitable thermoseeds for cancer treatment by hyperthermia. Moreover, magnetic nanomaterials offer a wide range of possibilities for diagnosis and therapy. These nanoparticles may be conjugated with therapeutic agents and heat the surrounding tissue under the action of alternating magnetic fields, enabling hyperthermia of cancer as an effective adjunct to chemotherapy regimens.

  2. Template synthesis of ordered macroporous hydroxyapatite bioceramics.

    Science.gov (United States)

    Ji, Lijun; Jell, Gavin; Dong, Yixiang; Jones, Julian R; Stevens, Molly M

    2011-08-28

    Hydroxyapatite has found wide application in bone tissue engineering. Here we use a macroporous carbon template to generate highly ordered macroporous hydroxyapatite bioceramics composed of close-packed hollow spherical pores with interconnected channels. The template has advantages for the preparation of ordered materials.

  3. Sintering of calcium phosphate bioceramics.

    Science.gov (United States)

    Champion, E

    2013-04-01

    Calcium phosphate ceramics have become of prime importance for biological applications in the field of bone tissue engineering. This paper reviews the sintering behaviour of these bioceramics. Conventional pressureless sintering of hydroxyapatite, Ca10(PO4)6(OH)2, a reference compound, has been extensively studied. Its physico-chemistry is detailed. It can be seen as a competition between two thermally activated phenomena that proceed by solid-state diffusion of matter: densification and grain growth. Usually, the objective is to promote the first and prevent the second. Literature data are analysed from sintering maps (i.e. grain growth vs. densification). Sintering trajectories of hydroxyapatite produced by conventional pressureless sintering and non-conventional techniques, including two-step sintering, liquid phase sintering, hot pressing, hot isostatic pressing, ultrahigh pressure, microwave and spark plasma sintering, are presented. Whatever the sintering technique may be, grain growth occurs mainly during the last step of sintering, when the relative bulk density reaches 95% of the maximum value. Though often considered very advantageous, most assisted sintering techniques do not appear very superior to conventional pressureless sintering. Sintering of tricalcium phosphate or biphasic calcium phosphates is also discussed. The chemical composition of calcium phosphate influences the behaviour. Similarly, ionic substitutions in hydroxyapatite or in tricalcium phosphate create lattice defects that modify the sintering rate. Depending on their nature, they can either accelerate or slow down the sintering rate. The thermal stability of compounds at the sintering temperature must also be taken into account. Controlled atmospheres may be required to prevent thermal decomposition, and flash sintering techniques, which allow consolidation at low temperature, can be helpful.

  4. Bioceramic-Based Root Canal Sealers: A Review

    Science.gov (United States)

    Che Ab Aziz, Zeti A.

    2016-01-01

    Bioceramic-based root canal sealers are considered to be an advantageous technology in endodontics. The aim of this review was to consider laboratory experiments and clinical studies of these sealers. An extensive search of the endodontic literature was made to identify publications related to bioceramic-based root canal sealers. The outcome of laboratory and clinical studies on the biological and physical properties of bioceramic-based sealers along with comparative studies with other sealers was assessed. Several studies were evaluated covering different properties of bioceramic-based sealers including physical properties, biocompatibility, sealing ability, adhesion, solubility, and antibacterial efficacy. Bioceramic-based sealers were found to be biocompatible and comparable to other commercial sealers. The clinical outcomes associated with the use of bioceramic-based root canal sealers are not established in the literature. PMID:27242904

  5. Contraceptive Efficacy and Local Effects of Bioceramic IUD in Rat

    Institute of Scientific and Technical Information of China (English)

    WANG Yan; ZHANG Yuanzhen; YAN Yuhua; CHEN Weimin; LIU Wenhui; ZU Meiping

    2006-01-01

    The contraceptive efficacy and local effects of bioceramic IUD in rat were studied. The experiment was divided into four groups: bioceramic IUD group; stainless steel IUD group; operation control group; normal control group. All IUD samples were put into uterus of rats. The experimental results show that the alumina bioceramic has a strong contraceptive effect for those rats. In bioceramic IUD group the endometrial inflammation reaction was as mild as that in stainless IUD group during the early days (30 days ) and gradually abated with time during the late days (60 days ). The experiments show that the alumina bioceramic has a good biocompatibility and contraceptive effects and hint at the alumina bioceramic IUD may become a more safety reproduction family planning IUD.

  6. Antibacterial Activity of Silicate Bioceramics

    Institute of Scientific and Technical Information of China (English)

    HU Sheng; NING Congqin; ZHOU Yue; CHEN Lei; LIN Kaili; CHANG Jiang

    2011-01-01

    Four kinds of pure silicate ceramic particles, CaSiO3, Ca3SiO5, bredigite and akermanite were prepared and their bactericidal effects were systematically investigated. The phase compositions of these silicate ceramics were characterized by XRD. The ionic concentration meas urement revealed that the Calcium (Ca) ion concentration were relatively higher in Ca3SiO5 and bredigite, and much lower in CaSiO3 and akermanite. Accordingly, the pH values of the four silicate ceramics extracts showed a positive correlation with the particle concentrations. Meanwhile, by decreasing the particle size, higher Ca ion concentrations can be achieved, leading to the increase of aqueous pH value as well. In summary, all of the four silicate ceramics tested in our study showed antibacterial effect in a dose-dependent manner. Generally, the order of their antibacterial activity against E.coli from strong to weak is Ca3SiO5, bredigite, CaSiO3 and akermanite.

  7. Bioceramics for osteogenesis, molecular and cellular advances.

    Science.gov (United States)

    Demirkiran, Hande

    2012-01-01

    The remarkable need for bone tissue replacement in clinical situations, its limited availability and some major drawbacks of autologous (from the patient) and allogeneic (from a donor) bone grafts are driving researchers to search for alternative approaches for bone repair. In order to develop an appropriate bone substitute, one should understand bone structure and properties and its growth, which will guide researchers to select the optimal conditions for tissue culture and implantation. It's well accepted that bioceramics are excellent candidates as bone replacement with osteogenesis, osteoinduction and osteoconduction capacity. Therefore, the molecular and cellular interactions that take place at the surface of bioceramics and their relevance in osteogenesis excites many researchers to delve deeper into this line of research.

  8. Bioceramics and pharmaceuticals: A remarkable synergy

    Science.gov (United States)

    Vallet-Regí, María; Balas, Francisco; Colilla, Montserrat; Manzano, Miguel

    2007-09-01

    The research on controlled drug delivery systems using bioceramics as host matrices presents two distinct sides; one route aims at embedding pharmaceuticals in biomaterials designed for the reconstruction or regeneration of living tissues, in order to counteract inflammatory responses, infections, bone carcinomas and so forth, while the other route deals with the more traditional drug introduction systems, i.e. oral administration. The incorporation of pharmaceuticals to bioceramic matrices could be very interesting in clinical practice. It is rather common in these days for an orthopedic surgeon working in bone reconstruction to use bioceramics. An added value to the production of these ceramics would be the optional addition of pharmaceuticals such as antibiotics, anti-inflammatories, anti-carcinogens, etc. In this sense, if we take into account the infections statistics at hip joint prostheses, the incidence varies between 2 and 4%, reaching up to a 45% in bolts used as external fixation. One of the main problems in these situations is the access to the infected area of the bone, in order to deliver the adequate antibiotic. If the pharmaceutical could be included within the implant itself, the added value would be straightforward. And if the bioceramic is bioactive, and therefore precursor of new bone tissue, the capability to introduce peptides, proteins or growth factors at its pores could accelerate the bone regeneration processes. We are facing a fine example of multidisciplinary research, where the so-called transversal supply of knowledge from and between the domains of materials science, biology and medicine will empower the know-how and applications that shall, undoubtedly, give rise to new advances in science and technology.

  9. A Review of Bioceramics and Fibrin Sealant

    Directory of Open Access Journals (Sweden)

    Le Guéhennec L.

    2004-09-01

    Full Text Available This review focuses on bone substitute composites made by mixing ceramic biomaterials with fibrin sealants. Different biomaterials such as coral, bone-derived materials, bioactive glass ceramics, and synthetic calcium phosphate have been mixed with fibrin sealant, resulting in a combination of the biological properties of the two components. This type of association has not produced identical results in all studies. In the past for some, the addition of fibrin sealant to the biomaterial failed to produce any significant, positive effect on osteointegration, whereas others found a positive impact on bone colonization. Despite the negative biological effects reported previously, bioceramic-fibrin composites have been widely used in various types of bone surgery because they are easy to manipulate. In particular, the intra-operative preparation of these composites makes it possible to add bone growth factors or autologous osteoprogenitor cells prior to bone reconstruction. The bone growth factors and autologous osteoprogenitor cells associated with the bioceramic-fibrin composites should provide surgeons with tissue engineered grafts with enhanced osteointegrative properties. This review discusses both the advantages and disadvantages, as well as the future perspectives, of using bioceramic-fibrin composites in various clinical indications.

  10. The use of bioceramics in endodontics - literature review

    Science.gov (United States)

    JITARU, STEFAN; HODISAN, IOANA; TIMIS, LUCIA; LUCIAN, ANAMARIA; BUD, MARIUS

    2016-01-01

    Background and aim Bioceramics are ceramic compounds obtained both in situ and in vivo, by various chemical processes. Bioceramics exhibit excellent biocompatibility due to their similarity with biological materials, like hydroxyapatite. Bioceramics and multi-substituted hydroxyapatite or similar compounds have the ability to induce a regenerative response in the organism. The aim of this paper is to make a literature review on the main bioceramic materials currently used in endodontics and on their specific characteristics. Methods We conducted a search in the international databases (PubMed), to identify publications in the last 10 years, using the following key words: “bioceramics endodontics”, “bioceramic endodontic cement”, “bioceramic sealer” and “direct pulp capping bioceramic”. Results Commonly used endodontic sealers (e.g., containing zinc oxide, calcium hydroxide and a resin) have a long tradition in scientific research and clinical use in endodontics. For specific cases, like root resorptions, perforations, apexification, and retrograde fillings, new biocompatible materials were developed in order to improve the clinical outcome: ProRooT MTA (Dentsply Company, Germany); Biodentine (Septodont, France); Endosequence BC sealer (Brassler, SUA); Bioaggregate (IBC, Canada); Generex A (Dentsply Tulsa Dental Specialties, USA). Conclusion The studies are generally in favor of bioceramic materials even if there are not many products available on the market for endodontic use. As more products are launched and more research is performed regarding these materials, we will provide more reliable data on clinical outcome. PMID:27857514

  11. Bioactivity of calcium phosphate bioceramic coating fabricated by laser cladding

    Science.gov (United States)

    Zhu, Yizhi; Liu, Qibin; Xu, Peng; Li, Long; Jiang, Haibing; Bai, Yang

    2016-05-01

    There were always strong expectations for suitable biomaterials used for bone regeneration. In this study, to improve the biocompatiblity of titanium alloy, calcium phosphate bioceramic coating was obtained by laser cladding technology. The microstructure, phases, bioactivity, cell differentiation, morphology and resorption lacunae were investigated by optical microscope (OM), x-ray diffraction (XRD), methyl thiazolyl tetrazolium (MTT) assay, tartrate-resistant acid phosphatase (TRAP) staining and scanning electronic microscope (SEM), respectively. The results show that bioceramic coating consists of three layers, which are a substrate, an alloyed layer and a ceramic layer. Bioactive phases of β-tricalcium phosphate (β-TCP) and hydroxyapatite (HA) were found in ceramic coating. Osteoclast precursors have excellent proliferation on the bioceramic surface. The bioceramics coating could be digested by osteoclasts, which led to the resorption lacunae formed on its surface. It revealed that the gradient bioceramic coating has an excellent bioactivity.

  12. Preparation of laponite bioceramics for potential bone tissue engineering applications.

    Directory of Open Access Journals (Sweden)

    Chuanshun Wang

    Full Text Available We report a facile approach to preparing laponite (LAP bioceramics via sintering LAP powder compacts for bone tissue engineering applications. The sintering behavior and mechanical properties of LAP compacts under different temperatures, heating rates, and soaking times were investigated. We show that LAP bioceramic with a smooth and porous surface can be formed at 800°C with a heating rate of 5°C/h for 6 h under air. The formed LAP bioceramic was systematically characterized via different methods. Our results reveal that the LAP bioceramic possesses an excellent surface hydrophilicity and serum absorption capacity, and good cytocompatibility and hemocompatibility as demonstrated by resazurin reduction assay of rat mesenchymal stem cells (rMSCs and hemolytic assay of pig red blood cells, respectively. The potential bone tissue engineering applicability of LAP bioceramic was explored by studying the surface mineralization behavior via soaking in simulated body fluid (SBF, as well as the surface cellular response of rMSCs. Our results suggest that LAP bioceramic is able to induce hydroxyapatite deposition on its surface when soaked in SBF and rMSCs can proliferate well on the LAP bioceramic surface. Most strikingly, alkaline phosphatase activity together with alizarin red staining results reveal that the produced LAP bioceramic is able to induce osteoblast differentiation of rMSCs in growth medium without any inducing factors. Finally, in vivo animal implantation, acute systemic toxicity test and hematoxylin and eosin (H&E-staining data demonstrate that the prepared LAP bioceramic displays an excellent biosafety and is able to heal the bone defect. Findings from this study suggest that the developed LAP bioceramic holds a great promise for treating bone defects in bone tissue engineering.

  13. Preparation of laponite bioceramics for potential bone tissue engineering applications.

    Science.gov (United States)

    Wang, Chuanshun; Wang, Shige; Li, Kai; Ju, Yaping; Li, Jipeng; Zhang, Yongxing; Li, Jinhua; Liu, Xuanyong; Shi, Xiangyang; Zhao, Qinghua

    2014-01-01

    We report a facile approach to preparing laponite (LAP) bioceramics via sintering LAP powder compacts for bone tissue engineering applications. The sintering behavior and mechanical properties of LAP compacts under different temperatures, heating rates, and soaking times were investigated. We show that LAP bioceramic with a smooth and porous surface can be formed at 800°C with a heating rate of 5°C/h for 6 h under air. The formed LAP bioceramic was systematically characterized via different methods. Our results reveal that the LAP bioceramic possesses an excellent surface hydrophilicity and serum absorption capacity, and good cytocompatibility and hemocompatibility as demonstrated by resazurin reduction assay of rat mesenchymal stem cells (rMSCs) and hemolytic assay of pig red blood cells, respectively. The potential bone tissue engineering applicability of LAP bioceramic was explored by studying the surface mineralization behavior via soaking in simulated body fluid (SBF), as well as the surface cellular response of rMSCs. Our results suggest that LAP bioceramic is able to induce hydroxyapatite deposition on its surface when soaked in SBF and rMSCs can proliferate well on the LAP bioceramic surface. Most strikingly, alkaline phosphatase activity together with alizarin red staining results reveal that the produced LAP bioceramic is able to induce osteoblast differentiation of rMSCs in growth medium without any inducing factors. Finally, in vivo animal implantation, acute systemic toxicity test and hematoxylin and eosin (H&E)-staining data demonstrate that the prepared LAP bioceramic displays an excellent biosafety and is able to heal the bone defect. Findings from this study suggest that the developed LAP bioceramic holds a great promise for treating bone defects in bone tissue engineering.

  14. Surface toughness of silicon nitride bioceramics: II, Comparison with commercial oxide materials.

    Science.gov (United States)

    McEntire, Bryan J; Enomoto, Yuto; Zhu, Wenliang; Boffelli, Marco; Marin, Elia; Pezzotti, Giuseppe

    2016-02-01

    Raman microprobe-assisted indentation, a micromechanics method validated in a companion paper, was used to compare the surface toughening behaviors of silicon nitride (Si3N4) and alumina-based bioceramics employed in joint arthroplasty (i.e., monolithic alumina, Al2O3, and yttria-stabilized zirconia (ZrO2)-toughened alumina, ZTA). Quantitative assessments of microscopic stress fields both ahead and behind the tip of Vickers indentation cracks propagated under increasing indentation loads were systematically made using a Raman microprobe with spatial resolution on the order of a single micrometer. Concurrently, crack opening displacement (COD) profiles were monitored on the same microcracks screened by Raman spectroscopy. The Raman eye clearly visualized different mechanisms operative in toughening Si3N4 and ZTA bioceramics (i.e., crack-face bridging and ZrO2 polymorphic transformation, respectively) as compared to the brittle behavior of monolithic Al2O3. Moreover, emphasis was placed on assessing not only the effectiveness but also the durability of such toughening effects when the biomaterials were aged in a hydrothermal environment. A significant degree of embrittlement at the biomaterial surface was recorded in the transformation-toughened ZTA, with the surface toughness reduced by exposure to the hydrothermal environment. Conversely, the Si3N4 biomaterial experienced a surface toughness value independent of hydrothermal attack. Crack-face bridging thus appears to be a durable surface toughening mechanism for biomaterials in joint arthroplasty.

  15. Wettability and interfacial interactions in bioceramic-body-liquid systems.

    Science.gov (United States)

    Agathopoulos, S; Nikolopoulos, P

    1995-04-01

    Wetting experiments, by the sessile drop technique, were carried out at 37 degrees C in air to determine the surface and interfacial interactions that take place in various solid bioceramics based on Al2O3, ZrO2(YPZ), SiO2, and TiO2 in contact with water, Ringer solution, artificial synovial fluid, calf serum, human plasma, and whole blood (+ EDTA). The surface energy of the liquids was measured by the ring method. The calculated values of the energy of interaction (work of adhesion) reveal that intermolecular forces act across the solid-liquid interfaces. The contribution of the dispersion and polar interactions to the surface energy of the polar liquids and the pure or mixed oxides was determined assuming that in the system of Mn-steel-liquids only dispersion forces act at the interface. It was found that the contribution of the polar interactions to the energy of interaction at the solid-liquid interface increases with the glassy phase content of the oxide that causes reduction of the measured contact angle.

  16. Investigating the surface reactivity of SiO2-TiO2-CaO-Na2O/SrO bioceramics as a function of structure and incubation time in simulated body fluid.

    Science.gov (United States)

    Li, Y; Coughlan, A; Wren, Anthony W

    2014-08-01

    This study focuses on evaluating the biocompatibility of a SiO2-TiO2-CaO-Na2O/SrO glass and glass-ceramic series. Glass and ceramic samples were synthesized and characterized using X-ray diffraction. Each material was subject to maturation in simulated body fluid over 1, 7 and 30 days to describe any changes in surface morphology. Calcium phosphate (CaP) deposition was observed predominantly on the Na(+) containing amorphous and crystalline materials, with plate-like morphology. The precipitated surface layer was also observed to crystallize with respect to maturation, which was most evident in the amorphous Na(+) containing glasses, Ly-N and Ly-C. The addition of Sr(2+) greatly reduced the solubility of all samples, with limited CaP precipitation on the amorphous samples and no deposition on the crystalline materials. The morphology of the samples was also different, presenting irregular plate-like structures (Ly-N), needle-like deposits (Ly-C) and globular-like structures (Ly-S). Cell culture analysis presented a significant increase in cell viability with the Na(+) materials, 134%, while the Sr(2+) containing glasses, 60-80% and ceramics, 60-85% presented a general reduction in cell viability, however these reductions were not significant.

  17. Promising trends of bioceramics in the biomaterials field.

    Science.gov (United States)

    Arcos, D; Izquierdo-Barba, I; Vallet-Regí, M

    2009-02-01

    Biomedical scientific community is currently demanding new advances in the designing of 3rd generation bioceramics, which promote bone tissue regeneration. In the last years, the development of supramolecular chemistry and the application of organic-inorganic hybrid materials in the biomedical field have resulted in a new generation of advanced bioceramics, which exhibit fascinating properties for regenerative purposes together with the possibility of being used as carriers of biologically active molecules. This communication overviews the evolution occurred from the first silica based bioceramics to the last advances in the synthesis of bioceramics for bone tissue regeneration. A critical review concerning the first bioactive glasses as well as the newest hybrid bioactive materials and templated mesoporous bioactive systems, will be performed from the point of view of their potential applications as replacement materials in bone repair and regeneration.

  18. Calcium Orthophosphates as Bioceramics: State of the Art

    OpenAIRE

    Dorozhkin, Sergey V

    2010-01-01

    In the late 1960s, much interest was raised in regard to biomedical applications of various ceramic materials. A little bit later, such materials were named bioceramics. This review is limited to bioceramics prepared from calcium orthophosphates only, which belong to the categories of bioactive and bioresorbable compounds. There have been a number of important advances in this field during the past 30–40 years. Namely, by structural and compositional control, it became possible to choose whet...

  19. The Bisphosphonate Clodronate Modifying Hydroxyapatite Bioceramics for Bone Scaffold

    Institute of Scientific and Technical Information of China (English)

    2005-01-01

    To investigate the efficiency of clodronate modifying HA bioceramics , and to evaluate the effect of clodronate modifying HA bioceramies on the cells in vitro, clodronate modified the porous HA bioceramics for bone scaffold by chelation. The outermost layer of the specimens was analyzed by XPS and FI- IR. The depth profile was investigated by the argon-ion sputtering method. The cell culture test was conducted using MC3 T3-E1 osteoblastic cells. The cells were inoculated and cultured on the scaffolds. Morphological observation of the cells,MTT test and ALP activity test evaluated the cell attachment, proliferation and activity on the materials. Characteristic peaks in XPS and FT-IR spectra indicated clodronate being immobilized on the surface of the bioceramics.The cell culture test in cell quantity and morphology indicated active proliferation of the cells on the scaffolds. The ALP activity of the cells cultured for 3d and 7 d on clodronate- HA bioceramics was slightly higher than that on HA bioceramics, but the difference was not significant. This result indicated that clodronate- HA bioceramics had favorable cytocompatibility to be used as bone scaffold with potential ability to improve osteogenesis.

  20. Calcium orthophosphates as bioceramics: state of the art.

    Science.gov (United States)

    Dorozhkin, Sergey V

    2010-11-30

    In the late 1960s, much interest was raised in regard to biomedical applications of various ceramic materials. A little bit later, such materials were named bioceramics. This review is limited to bioceramics prepared from calcium orthophosphates only, which belong to the categories of bioactive and bioresorbable compounds. There have been a number of important advances in this field during the past 30-40 years. Namely, by structural and compositional control, it became possible to choose whether calcium orthophosphate bioceramics were biologically stable once incorporated within the skeletal structure or whether they were resorbed over time. At the turn of the millennium, a new concept of calcium orthophosphate bioceramics-which is able to promote regeneration of bones-was developed. Presently, calcium orthophosphate bioceramics are available in the form of particulates, blocks, cements, coatings, customized designs for specific applications and as injectable composites in a polymer carrier. Current biomedical applications include artificial replacements for hips, knees, teeth, tendons and ligaments, as well as repair for periodontal disease, maxillofacial reconstruction, augmentation and stabilization of the jawbone, spinal fusion and bone fillers after tumor surgery. Exploratory studies demonstrate potential applications of calcium orthophosphate bioceramics as scaffolds, drug delivery systems, as well as carriers of growth factors, bioactive peptides and/or various types of cells for tissue engineering purposes.

  1. Ion-Doped Silicate Bioceramic Coating of Ti-Based Implant

    Science.gov (United States)

    Mohammadi, Hossein; Sepantafar, Mohammadmajid

    2016-01-01

    Titanium and its alloy are known as important load-bearing biomaterials. The major drawbacks of these metals are fibrous formation and low corrosion rate after implantation. The surface modification of biomedical implants through various methods such as plasma spray improves their osseointegration and clinical lifetime. Different materials have been already used as coatings on biomedical implant, including calcium phosphates and bioglass. However, these materials have been reported to have limited clinical success. The excellent bioactivity of calcium silicate (Ca-Si) has been also regarded as coating material. However, their high degradation rate and low mechanical strength limit their further coating application. Trace element modification of (Ca-Si) bioceramics is a promising method, which improves their mechanical strength and chemical stability. In this review, the potential of trace element-modified silicate coatings on better bone formation of titanium implant is investigated. PMID:26979401

  2. Novel Bioceramic Urethral Bulking Agents Elicit Improved Host Tissue Responses in a Rat Model

    Directory of Open Access Journals (Sweden)

    Travis K. Mann-Gow

    2016-01-01

    Full Text Available Objectives. To test the physical properties and host response to the bioceramic particles, silica-calcium phosphate (SCPC10 and Cristobalite, in a rat animal model and compare their biocompatibility to the current clinically utilized urethral bulking materials. Material and Methods. The novel bulking materials, SCPC10 and Cristobalite, were suspended in hyaluronic acid sodium salt and injected into the mid urethra of a rat. Additional animals were injected with bulking materials currently in clinical use. Physiological response was assessed using voiding trials, and host tissue response was evaluated using hard tissue histology and immunohistochemical analysis. Distant organs were evaluated for the presence of particles or their components. Results. Histological analysis of the urethral tissue five months after injection showed that both SCPC10 and Cristobalite induced a more robust fibroblastic and histiocytic reaction, promoting integration and encapsulation of the particle aggregates, leading to a larger bulking effect. Concentrations of Ca, Na, Si, and P ions in the experimental groups were comparable to control animals. Conclusions. This side-by-side examination of urethral bulking agents using a rat animal model and hard tissue histology techniques compared two newly developed bioactive ceramic particles to three of the currently used bulking agents. The local host tissue response and bulking effects of bioceramic particles were superior while also possessing a comparable safety profile.

  3. Novel Bioceramic Urethral Bulking Agents Elicit Improved Host Tissue Responses in a Rat Model

    Science.gov (United States)

    Mann-Gow, Travis K.; King, Benjamin J.; El-Ghannam, Ahmed; Knabe-Ducheyne, Christine; Kida, Masatoshi; Dall, Ole M.; Krhut, Jan

    2016-01-01

    Objectives. To test the physical properties and host response to the bioceramic particles, silica-calcium phosphate (SCPC10) and Cristobalite, in a rat animal model and compare their biocompatibility to the current clinically utilized urethral bulking materials. Material and Methods. The novel bulking materials, SCPC10 and Cristobalite, were suspended in hyaluronic acid sodium salt and injected into the mid urethra of a rat. Additional animals were injected with bulking materials currently in clinical use. Physiological response was assessed using voiding trials, and host tissue response was evaluated using hard tissue histology and immunohistochemical analysis. Distant organs were evaluated for the presence of particles or their components. Results. Histological analysis of the urethral tissue five months after injection showed that both SCPC10 and Cristobalite induced a more robust fibroblastic and histiocytic reaction, promoting integration and encapsulation of the particle aggregates, leading to a larger bulking effect. Concentrations of Ca, Na, Si, and P ions in the experimental groups were comparable to control animals. Conclusions. This side-by-side examination of urethral bulking agents using a rat animal model and hard tissue histology techniques compared two newly developed bioactive ceramic particles to three of the currently used bulking agents. The local host tissue response and bulking effects of bioceramic particles were superior while also possessing a comparable safety profile. PMID:27688751

  4. Calcium Orthophosphates as Bioceramics: State of the Art

    Directory of Open Access Journals (Sweden)

    Sergey V. Dorozhkin

    2010-11-01

    Full Text Available In the late 1960s, much interest was raised in regard to biomedical applications of various ceramic materials. A little bit later, such materials were named bioceramics. This review is limited to bioceramics prepared from calcium orthophosphates only, which belong to the categories of bioactive and bioresorbable compounds. There have been a number of important advances in this field during the past 30–40 years. Namely, by structural and compositional control, it became possible to choose whether calcium orthophosphate bioceramics were biologically stable once incorporated within the skeletal structure or whether they were resorbed over time. At the turn of the millennium, a new concept of calcium orthophosphate bioceramics—which is able to promote regeneration of bones—was developed. Presently, calcium orthophosphate bioceramics are available in the form of particulates, blocks, cements, coatings, customized designs for specific applications and as injectable composites in a polymer carrier. Current biomedical applications include artificial replacements for hips, knees, teeth, tendons and ligaments, as well as repair for periodontal disease, maxillofacial reconstruction, augmentation and stabilization of the jawbone, spinal fusion and bone fillers after tumor surgery. Exploratory studies demonstrate potential applications of calcium orthophosphate bioceramics as scaffolds, drug delivery systems, as well as carriers of growth factors, bioactive peptides and/or various types of cells for tissue engineering purposes.

  5. Effect of bioceramic functional groups on drug binding and release kinetics

    Science.gov (United States)

    Trujillo, Christopher

    Bioceramics have been studied extensively as drug delivery systems (DDS). Those studies have aimed to tailor the drug binding and release kinetics to successfully treat infections and other diseases. This research suggests that the drug binding and release kinetics are predominantly driven by the functional groups available on the surface of a bioceramic. The goal of the present study is to explain the role of silicate and phosphate functional groups in drug binding to and release kinetics from bioceramics. alpha-cristobalite (Cris; SiO2) particles (90-150 microm) were prepared and doped with 0 microg (P-0), 39.1 microg (P-39.1), 78.2 microg (P-78.2), 165.5 microg (P-165.5) or 331 microg (P-331) of P 2O5 per gram Cris, using 85% orthophosphoric (H3PO 4) acid and thermal treatment. The material structure was analyzed using X-ray diffraction (XRD) with Rietveld Refinement and Fourier Transform Infrared (FTIR) spectroscopy with Gaussian fitting. XRD demonstrated an increase from sample P-0 (170.5373 A3) to P-331 (170.6466 A 3) in the unit cell volume as the P2O5 concentration increased in the material confirming phosphate silicate substitution in Cris. Moreover, FTIR showed the characteristic bands of phosphate functional groups of nu4 PO4/O-P-O bending, P-O-P stretching, P-O-P bending, P=O stretching, and P-O-H bending in doped Cris indicating phosphate incorporation in the silicate structure. Furthermore, FTIR showed that the nu4 PO4/O-P-O bending band around 557.6 cm-1 and P=O stretching band around 1343.9 cm-1 increased in area for samples P-39.1 to P-331 from 3.5 to 10.5 and from 10.1 to 22.4, respectively due to phosphate doping. In conjunction with the increase of the nu4 PO4/O-P-O bending band and P=O stretching band, a decrease in area of the O-Si-O bending bands around 488.1 and 629.8 cm-1 was noticed for samples P-39.1 to P-331 from 5 to 2 and from 11.8 to 5.4, respectively. Furthermore, Cris samples (200 mg, n=5 for each sample) were immersed separately in

  6. Fabrication of CTP/HAp novel gradient composite bioceramics

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    Calcium-titanium-phosphate(CaTi4(PO4)6, CTP)/hydroxyapatite(HAp) is a kind of novel gradient composite bioceramics,which has excellent biocompatibility and bioactivity. CTP ceramic film was synthesized one-step on the surface of titanium using micro-arc oxidation(MAO). The CTP/HAp composite bioceramics were prepared by soaking CTP film in HAp inducing solution for several days. XRD, SEM and EDX were used to characterize the bio-ceramic films phase and composition, morphology and component. The influence of electrolyte molar ratio of Ca to P and the current density to the synthesis of film was studied, and the optimized value of parameters above were 1/6 and 15A/dm2. The parameters of HAp inducing solution, such as component and pH value were also studied and the best pH value which is adjusted by NaOH is 6.4.

  7. Mesenchymal Stem Cells and Nano-Bioceramics for Bone Regeneration.

    Science.gov (United States)

    Kankilic, Berna; Köse, Sevil; Korkusuz, Petek; Timuçin, Muharrem; Korkusuz, Feza

    Orthopedic disorders and trauma usually result in bone loss. Bone grafts are widely used to replace this tissue. Bone grafts excluding autografts unfortunately have disadvantages like evoking immune response, contamination and rejection. Autografts are of limited sources and optimum biomaterials that can replace bone have been searched for several decades. Bioceramics, which have the similar inorganic structure of natural bone, are widely used to regenerate bone or coat metallic implants. As people continuously look for a higher life quality, there are developments in technology almost everyday to meet their expectations. Nanotechnology is one of such technologies and it attracts everyone's attention in biomaterial science. Nano scale biomaterials have many advantages like larger surface area and higher biocompatibility and these properties make them more preferable than micro scale. Also, stem cells are used for bone regeneration besides nano-bioceramics due to their differentiation characteristics. This review covers current research on nano-bioceramics and mesenchymal stem cells and their role in bone regeneration.

  8. Macroporous bioceramics: a remarkable material for bone regeneration.

    Science.gov (United States)

    Lew, Kien-Seng; Othman, Radzali; Ishikawa, Kunio; Yeoh, Fei-Yee

    2012-09-01

    This review summarises the major developments of macroporous bioceramics used mainly for repairing bone defects. Porous bioceramics have been receiving attention ever since their larger surface area was reported to be beneficial for the formation of more rigid bonds with host tissues. The study of porous bioceramics is important to overcome the less favourable bonds formed between dense bioceramics and host tissues, especially in healing bone defects. Macroporous bioceramics, which have been studied extensively, include hydroxyapatite, tricalcium phosphate, alumina, and zirconia. The pore size and interconnections both have significant effects on the growth rate of bone tissues. The optimum pore size of hydroxyapatite scaffolds for bone growth was found to be 300 µm. The existence of interconnections between pores is critical during the initial stage of tissue ingrowth on porous hydroxyapatite scaffolds. Furthermore, pore formation on β-tricalcium phosphate scaffolds also allowed the impregnation of growth factors and cells to improve bone tissues growth significantly. The formation of vascularised tissues was observed on macroporous alumina but did not take place in the case of dense alumina due to its bioinert nature. A macroporous alumina coating on scaffolds was able to improve the overall mechanical properties, and it enabled the impregnation of bioactive materials that could increase the bone growth rate. Despite the bioinertness of zirconia, porous zirconia was useful in designing scaffolds with superior mechanical properties after being coated with bioactive materials. The pores in zirconia were believed to improve the bone growth on the coated system. In summary, although the formation of pores in bioceramics may adversely affect mechanical properties, the advantages provided by the pores are crucial in repairing bone defects.

  9. Silicate Bioceramics for Bone Tissue Regeneration%硅酸盐生物活性陶瓷用于骨组织修复及再生的研究

    Institute of Scientific and Technical Information of China (English)

    吴成铁; 常江

    2013-01-01

    近年来,硅酸盐生物活性陶瓷越来越受到研究人员的重视,其主要原因在于硅酸盐生物陶瓷能够通过释放硅(Si)离子等生物活性离子,显著地促进骨组织细胞的增殖、分化及骨组织修复.硅酸盐生物活性陶瓷有望作为新的陶瓷体系广泛应用于骨缺损修复和再生.本文将结合本课题组在过去十年的研究,重点介绍目前硅酸盐生物活性陶瓷用于骨组织修复及再生的研究进展.同时,通过与传统磷酸钙类生物陶瓷进行比较,对硅酸盐生物活性陶瓷的优缺点进行分析和归纳,最后对硅酸盐陶瓷作为新的生物陶瓷体系用于骨组织修复的前景做了展望.%Silicate bioceramics have received significant attention in the past several years. The main reason is that silicate bioceramics can efficiently stimulate the proliferation, differentiation and gene expression of tissue cells as well as the regeneration of bone tissue by release of Si-containing ionic products. Due to this significant advantage, silicate bioceramics, as a novel bioceramic system, have great potential to be widely used for repairing and regenerating bone tissues. In this paper, our researches in the past ten years are combined and the research advancements of silicate bioceramics are reviewed. The advantages and disadvantages of silicate bioceramics are summarized by comparing with conventional calcium phosphate bioceramics. Finally, a forward-looking perspective for silicate bioceramics on the applications of bone regeneration is also discussed.

  10. Processing and Characterization of Novel Biomimetic Nanoporous Bioceramic Surface on β-Ti Implant by Powder Mixed Electric Discharge Machining

    Science.gov (United States)

    Prakash, Chander; Kansal, H. K.; Pabla, B. S.; Puri, Sanjeev

    2015-09-01

    Herein, a β-Ti-based implant was subjected to powder mixed electric discharge machining (PMEDM) for surface modification to produce a novel biomimetic nanoporous bioceramic surface. The microstructure, surface topography, and phase composition of the non-machined and machined (PMEDMed) surfaces were investigated using field-emission scanning electron microscopy, energy-dispersive x-ray spectroscopy, and x-ray diffraction. The microhardness of the surfaces was measured on a Vickers hardness tester. The corrosion resistance of the surfaces was evaluated via potentiodynamic polarization measurements in simulated body fluid. The application of PMEDM not only altered the surface chemistry, but also imparted the surface with a nanoporous topography or a natural bone-like surface structure. The characterization results confirmed that the alloyed layer mainly comprised bioceramic oxides and carbide phases (TiO2, Nb2O5, ZrO2, SiO2, TiC, NbC, SiC). The microhardness of PMEDMed surface was twofold higher than that of the base material (β-Ti alloy), primarily because of the formation of the hard carbide phases on the machined layer. Electrochemical analysis revealed that PMEDMed surface featured insulative and protective properties and thus displayed higher corrosion resistance ability when compared with the non-machined surface. This result was attributed to the formation of the bioceramic oxides on the machined surface. Additionally, the in vitro biocompatibility of the surfaces was evaluated using human osteoblastic cell line MG-63. PMEDMed surface with a micro-, sub-micro-, and nano-structured topography exhibited bioactivity and improved biocompatibility relative to β-Ti surface. Furthermore, PMEDMed surface enabled better adhesion and growth of MG-63 when compared with the non-machined substrate.

  11. Wear analysis and finishing of bioceramic implant surfaces.

    Science.gov (United States)

    Denkena, Berend; Reichstein, Martin; van der Meer, Marijke; Ostermeier, Sven; Hurschler, Christof

    2008-01-01

    A primary cause for revision operations of joint replacements is the implant loosening, due to immune reactions resulting from the agglomeration of polyethylene wear debris. Motivated by the successful application of bioceramic materials in hip joint prostheses, a trend towards the development of hard implant materials has occurred. Nonetheless in the area of total knee arthroplasty (TKA), modern efforts have still utilized polyethylene as the tibial-inlay joint component. The use of bioceramic hard-hard-pairings for total knee arthroplasty has been prevented by the complex kinematics and geometries required. Ceramics cannot cope with non-uniform loads, which suggests the need for new designs appropriate to the material. Furthermore, biomechanical requirements should be considered. A rolling-gliding wear simulator, which reproduces the movements and stresses of the knee joint on specimens of simplified geometry, has therefore been developed. High-precision machining processes for free formed bioceramic surfaces, with suitable grinding and polishing tools which adjust to constantly changing contact conditions, are essential. The goal is to put automated finishing in one clamping with five simultaneous controlled axes into practice. The developed manufacturing technologies will allow the advantageous bioceramic materials to be applied and accepted for more complex joint replacements such as knee prostheses.

  12. A comparative study of calcium phosphate formation on bioceramics in vitro and in vivo.

    Science.gov (United States)

    Xin, Renlong; Leng, Yang; Chen, Jiyong; Zhang, Qiyi

    2005-11-01

    Formation of calcium phosphate (Ca-P) on various bioceramic surfaces in simulated body fluid (SBF) and in rabbit muscle sites was investigated. The bioceramics were sintered porous solids, including bioglass, glass-ceramics, hydroxyapatite, alpha-tricalcium phosphate and beta-tricalcium phosphate. The ability of inducing Ca-P formation was compared among the bioceramics. The Ca-P crystal structures were identified using single-crystal diffraction patterns in transmission electron microscopy. The examination results show that ability of inducing Ca-P formation in SBF was similar among bioceramics, but considerably varied among bioceramics in vivo. Sintered beta-tricalcium phosphate exhibited a poor ability of inducing Ca-P formation both in vitro and in vivo. Octacalcium phosphate (OCP) formed on the surfaces of bioglass, A-W, hydroxyapatite and alpha-tricalcium phosphate in vitro and in vivo. Apatite formation in physiological environments cannot be confirmed as a common feature of bioceramics.

  13. Chemical functionalization of bioceramics to enhance endothelial cells adhesion for tissue engineering.

    Science.gov (United States)

    Borcard, Françoise; Staedler, Davide; Comas, Horacio; Juillerat, Franziska Krauss; Sturzenegger, Philip N; Heuberger, Roman; Gonzenbach, Urs T; Juillerat-Jeanneret, Lucienne; Gerber-Lemaire, Sandrine

    2012-09-27

    To control the selective adhesion of human endothelial cells and human serum proteins to bioceramics of different compositions, a multifunctional ligand containing a cyclic arginine-glycine-aspartate (RGD) peptide, a tetraethylene glycol spacer, and a gallate moiety was designed, synthesized, and characterized. The binding of this ligand to alumina-based, hydroxyapatite-based, and calcium phosphate-based bioceramics was demonstrated. The conjugation of this ligand to the bioceramics induced a decrease in the nonselective and integrin-selective binding of human serum proteins, whereas the binding and adhesion of human endothelial cells was enhanced, dependent on the particular bioceramics.

  14. Preparation and characterization of laser cladding wollastonite derived bioceramic coating on titanium alloy.

    Science.gov (United States)

    Li, Huan-cai; Wang, Dian-gang; Chen, Chuan-zhong; Weng, Fei; Shi, Hua

    2015-09-25

    The bioceramic coating is fabricated on titanium alloy (Ti6Al4V) by laser cladding the preplaced wollastonite (CaSiO3) powders. The coating on Ti6Al4V is characterized by x-ray diffraction, scanning electron microscopy coupled with energy dispersive spectroscopy, and attenuated total reflection Fourier-transform infrared. The interface bonding strength is measured using the stretching method using an RGD-5-type electronic tensile machine. The microhardness distribution of the cross-section is determined using an indentation test. The in vitro bioactivity of the coating on Ti6Al4V is evaluated using the in vitro simulated body fluid (SBF) immersion test. The microstructure of the laser cladding sample is affected by the process parameters. The coating surface is coarse, accidented, and microporous. The cross-section microstructure of the ceramic layer from the bottom to the top gradually changes from cellular crystal, fine cellular-dendrite structure to underdeveloped dendrite crystal. The coating on Ti6Al4V is composed of CaTiO3, CaO, α-Ca2SiO4, SiO2, and TiO2. After soaking in the SBF solution, the calcium phosphate layer is formed on the coating surface.

  15. Mechanical and Corrosion Properties of Magnesium-Bioceramic Nanocomposites

    Directory of Open Access Journals (Sweden)

    Kowalski K.

    2016-09-01

    Full Text Available Magnesium alloys have recently attracted much attention as a new generation of biodegradable metallic materials. In this work, Mg1Mn1Zn0.3Zr-bioceramic nanocomposites and their scaffolds were synthesized using a combination of mechanical alloying and a space-holder sintering process. The phase and microstructure analysis was carried out using X-ray diffraction, scanning electron microscopy and the properties were measured using hardness and corrosion testing equipment. Nanostructured Mg-bioceramic composites with a grain sizes below 73 nm were synthesized. The Vickers hardnesses for the bulk nanostructured Mg-based composites are two times greater than that of pure microcrystalline Mg metal (50 HV0.3. Produced Mg-based bionanomaterials can be applied in medicine.

  16. Bioceramics composed of octacalcium phosphate demonstrate enhanced biological behavior.

    Science.gov (United States)

    Komlev, Vladimir S; Barinov, Sergei M; Bozo, Ilya I; Deev, Roman V; Eremin, Ilya I; Fedotov, Alexander Yu; Gurin, Alex N; Khromova, Natalia V; Kopnin, Pavel B; Kuvshinova, Ekaterina A; Mamonov, Vasily E; Rybko, Vera A; Sergeeva, Natalia S; Teterina, Anastasia Yu; Zorin, Vadim L

    2014-10-08

    Bioceramics are used to treat bone defects but in general do not induce formation of new bone, which is essential for regeneration process. Many aspects related to bioceramics synthesis, properties and biological response that are still unknown and, there is a great need for further development. In the most recent research efforts were aimed on creation of materials from biological precursors of apatite formation in humans. One possible precursor is octacalcium phosphate (OCP), which is believed to not only exhibit osteoconductivity but possess osteoinductive quality, the ability to induce bone formation. Here we propose a relatively simple route for OCP ceramics preparation with a specifically designed microstructure. Comprehensive study for OCP ceramics including biodegradation, osteogenic properties in ortopic and heterotopic models and limited clinical trials were performed that demonstrated enhanced biological behavior. Our results provide a possible new concept for the clinical applications of OCP ceramics.

  17. MICROWAVE JOINING OF ALUMINA CERAMIC AND HYDROXYLAPATITE BIOCERAMIC

    Institute of Scientific and Technical Information of China (English)

    1999-01-01

    Microwave joining is a rapid developmental new techniqu e in recent years.This paper introduces a new microwave joining equipment which was made by our lab,succeeds in alumina ceramic-hydroxylapatite bioceramic j o in in the equipment, and analyzes the join situation of join boundary by using s canni ng electron microscope(SEM),this paper analyzes the mechanism of microwave joini ng also.

  18. Bioceramics and scaffolds: a winning combination for tissue engineering

    Directory of Open Access Journals (Sweden)

    Francesco eBaino

    2015-12-01

    Full Text Available In the last few decades we have assisted to a general increase of elder population worldwide with associated age-related pathologies. Therefore, there is the need for new biomaterials that can substitute damaged tissues, stimulate the body’s own regenerative mechanisms and promote tissue healing. Porous templates referred to as scaffolds are thought to be required for three-dimensional tissue growth. Bioceramics, a special set of fully, partially or non-crystalline ceramics (e.g. calcium phosphates, bioactive glasses and glass-ceramics that are designed for the repair and reconstruction of diseased parts of the body, have high potential as scaffold materials. Traditionally, bioceramics have been used to fill and restore bone and dental defects (repair of hard tissues. More recently, this category of biomaterials has also revealed promising applications in the field of soft tissue engineering. Starting with an overview of the fundamental requirements for tissue engineering scaffolds, this article provides a detailed picture on recent developments of porous bioceramics and composites, including a summary of common fabrication technologies and a critical analysis of structure-property and structure-function relationships. Areas of future research are highlighted at the end of this review, with special attention to the development of multifunctional scaffolds exploiting therapeutic ion/drug release and emerging applications beyond hard tissue repair.

  19. Preparation and properties of β-tricalcium phosphate porous bioceramic

    Institute of Scientific and Technical Information of China (English)

    张士华; 熊党生; 崔崇

    2004-01-01

    Porous β-tricalcium phosphate bioceramic (PTCP) has important roles in surgical implants because of good biocompatibility. But the low compressive strength of the ceramic limits its application. The preparation of PTCP was improved with the adjustment of the constituents and the sintering-process. A new type of PTCP material with high compressive strength was made. The compositions, microstructure and properties of PTCP were analyzed by TG-DSC, XRD, TEM, SEM and so on. The result indicates that stearic acid burns sufficiently and gives out carbon dioxide and water vapor when slowly heated between 200 ℃ and 400 ℃ so that the porous structure like coral in β-TCP bioceramic is formed. Through crystallization at 470 ℃ and 570 ℃, more CaO-P2O5 glass-cement is converted into crystallite-glass, which is beneficial for improving the compressive strength of β-TCP bioceramic.PTCP can form a support action in bone imperfect section with good solubility.

  20. Calcium phosphate bioceramics prepared from wet chemically precipitated powders

    Directory of Open Access Journals (Sweden)

    Kristine Salma

    2010-03-01

    Full Text Available In this work calcium phosphates were synthesized by modified wet chemical precipitation route. Contrary to the conventional chemical precipitation route calcium hydroxide was homogenized with planetary mill. Milling calcium oxide and water in planetary ball mill as a first step of synthesis provides a highly dispersed calcium hydroxide suspension. The aim of this work was to study the influence of main processing parameters of wet chemical precipitation synthesis product and to control the morphology, phase and functional group composition and, consequently, thermal stability and microstructure of calcium phosphate bioceramics after thermal treatment. The results showed that it is possible to obtain calcium phosphates with different and reproducible phase compositions after thermal processing (hydroxyapatite [HAp], β-tricalcium phosphate [β-TCP] and HAp/β-TCP by modified wet-chemical precipitation route. The β-TCP phase content in sintered bioceramics samples is found to be highly dependent on the changes in technological parameters and it can be controlled with ending pH, synthesis temperature and thermal treatment. Pure, crystalline and highly thermally stable (up to 1300°C HAp bioceramics with homogenous grainy microstructure, grain size up to 200–250 nm and high open porosity can be successfully obtained by powder synthesized at elevated synthesis temperature of 70°C and stabilizing ending pH at 9.

  1. Bioceramics and Scaffolds: A Winning Combination for Tissue Engineering.

    Science.gov (United States)

    Baino, Francesco; Novajra, Giorgia; Vitale-Brovarone, Chiara

    2015-01-01

    In the last few decades, we have assisted to a general increase of elder population worldwide associated with age-related pathologies. Therefore, there is the need for new biomaterials that can substitute damaged tissues, stimulate the body's own regenerative mechanisms, and promote tissue healing. Porous templates referred to as "scaffolds" are thought to be required for three-dimensional tissue growth. Bioceramics, a special set of fully, partially, or non-crystalline ceramics (e.g., calcium phosphates, bioactive glasses, and glass-ceramics) that are designed for the repair and reconstruction of diseased parts of the body, have high potential as scaffold materials. Traditionally, bioceramics have been used to fill and restore bone and dental defects (repair of hard tissues). More recently, this category of biomaterials has also revealed promising applications in the field of soft-tissue engineering. Starting with an overview of the fundamental requirements for tissue engineering scaffolds, this article provides a detailed picture on recent developments of porous bioceramics and composites, including a summary of common fabrication technologies and a critical analysis of structure-property and structure-function relationships. Areas of future research are highlighted at the end of this review, with special attention to the development of multifunctional scaffolds exploiting therapeutic ion/drug release and emerging applications beyond hard tissue repair.

  2. Effects of ions traces on the dissolution of bioceramics composed of hydroxyapatite and β-tricalcium phosphate

    Directory of Open Access Journals (Sweden)

    Mohamed Jamil

    2015-02-01

    Full Text Available The aim of this work is to study the effect of trace ions as Mg2+, Sr2+, (SiO44- and Al3+, brought by the raw material, on the dissolution of the calcium-phosphate bioceramics.  The precursor powders prepared by aqueous precipitation with molar ratio Ca / P = 1.630 ± 0.002, were calcined at 1100°C resulting in the formation of a mixture of hydroxyapatite (Ca10(PO46(OH2 and β-tricalcium phosphate (β-Ca3(PO42.  Two mixtures which differ by the content of trace ions were characterized for phase purity, chemical composition and morphology.  The dissolution tests were performed at 37 °C in acidic buffers solution at pH 4.8.  The results showed that the dissolution of calcium ions is more important in the presence of ions trace while the phosphor ions were not affected.  The dissolution and dissolution-reprecipitation observed of various ions trace can modify the surface properties of calcium phosphate bioceramics and therefore the properties of biological products, such as resorbtion and reactivity can be affected.

  3. Physiological effects of bioceramic material: harvard step, resting metabolic rate and treadmill running assessments.

    Science.gov (United States)

    Leung, Ting-Kai; Kuo, Chia-Hua; Lee, Chi-Ming; Kan, Nai-Wen; Hou, Chien-Wen

    2013-12-31

    Previous biomolecular and animal studies have shown that a room-temperature far-infrared-rayemitting ceramic material (bioceramic) demonstrates physical-biological effects, including the normalization of psychologically induced stress-conditioned elevated heart rate in animals. In this clinical study, the Harvard step test, the resting metabolic rate (RMR) assessment and the treadmill running test were conducted to evaluate possible physiological effects of the bioceramic material in human patients. The analysis of heart rate variability (HRV) during the Harvard step test indicated that the bioceramic material significantly increased the high-frequency (HF) power spectrum. In addition, the results of RMR analysis suggest that the bioceramic material reduced oxygen consumption (VO2). Our results demonstrate that the bioceramic material has the tendency to stimulate parasympathetic responses, which may reduce resting energy expenditure and improve cardiorespiratory recovery following exercise.

  4. Dynamics of Gradient Bioceramic Composite Coating on Surface of Titanium Alloy by Wide-Band Laser Cladding

    Institute of Scientific and Technical Information of China (English)

    LIU Qi-bin; ZOU Long-jiang; ZHU Wei-dong; LI Hai-tao; DONG Chuang

    2004-01-01

    The gradient bioceramic coating was prepared on the surface of titanium alloy using wide-band laser cladding. The dynamics of gradient bioceramic composite coating containing hydroxyapatite (HA) prepared with mixture of CaHPO4*2H2O and CaCO3 under the condition of wide-band laser was studied theoretically. The corresponding mathematical model and its numerical solution were presented. The examination experiment showed that HA bioceramic composite coatings can be obtained by appropriately choosing wide-band laser cladding parameters. The microstructure and surface morphology of HA bioceramic coating were observed by SEM and X-ray diffraction. The experimental results showed that the bioceramic coating is composed of HA, β-TCP, CaO, CaTiO3 and TiO2. The surface of bioceramic coating takes coral-shaped structure or short-rod piled structure, which helps osteoblast grow into bioceramic and improves the biocompatibility.

  5. XANES analysis of calcium and sodium phosphates and silicates and hydroxyapatite-Bioglass (registered) 45S5 co-sintered bioceramics

    Energy Technology Data Exchange (ETDEWEB)

    Demirkiran, Hande [Graduate Student, Materials Science and Engineering Department, University of Texas at Arlington, Arlington, TX (United States); Hu Yongfeng; Zuin, Lucia [Beamline Scientist, Canadian Light Source, Saskatoon, SK (Canada); Appathurai, Narayana [Beamline Scientist, Synchrotron Radiation Center, Madison, WI (United States); Aswath, Pranesh B., E-mail: aswath@uta.edu [Materials Science and Engineering Department, University of Texas at Arlington, Arlington, TX (United States)

    2011-03-12

    Bioglass (registered) 45S5 was co-sintered with hydroxyapatite at 1200 deg. C. When small amounts (< 5 wt.%) of Bioglass (registered) 45S5 was added it behaved as a sintering aid and also enhanced the decomposition of hydroxyapatite to {beta}-tricalcium phosphate. However when 10 wt.% and 25 wt.% Bioglass (registered) 45S5 was used it resulted in the formation of Ca{sub 5}(PO{sub 4}){sub 2}SiO{sub 4} and Na{sub 3}Ca{sub 6}(PO{sub 4}){sub 5} in an amorphous silicate matrix respectively. These chemistries show improved bioactivity compared to hydroxyapatite and are the subject of this study. The structure of several crystalline calcium and sodium phosphates and silicates as well as the co-sintered hydroxyapatite-Bioglass (registered) 45S5 bioceramics were examined using XANES spectroscopy. The nature of the crystalline and amorphous phases were studied using silicon (Si) and phosphorus (P) K- and L{sub 2,3}-edge and calcium (Ca) K-edge XANES. Si L{sub 2,3}-edge spectra of sintered bioceramic compositions indicates that the primary silicates present in these compositions are sodium silicates in the amorphous state. From Si K-edge spectra, it is shown that the silicates are in a similar structural environment in all the sintered bioceramic compositions with 4-fold coordination. Using P L{sub 2,3}-edge it is clearly shown that there is no evidence of sodium phosphate present in the sintered bioceramic compositions. In the P K-edge spectra, the post-edge shoulder peak at around 2155 eV indicates that this shoulder to be more defined for calcium phosphate compounds with decreasing solubility and increasing thermodynamic stability. This shoulder peak is more noticeable in hydroxyapatite and {beta}-TCP indicating greater stability of the phosphate phase. The only spectra that does not show a noticeable peak is the composition with Na{sub 3}Ca{sub 6}(PO{sub 4}){sub 5} in a silicate matrix indicating that it is more soluble compared to the other compositions.

  6. Influences of the steam sterilization on the properties of calcium phosphate porous bioceramics.

    Science.gov (United States)

    Li, Xiangfeng; Guo, Bo; Xiao, Yumei; Yuan, Tun; Fan, Yujiang; Zhang, Xingdong

    2016-01-01

    The influences of steam sterilization on the physicochemical properties of calcium phosphate (Ca-P) porous bioceramics, including β-tricalcium phosphate (β-TCP), biphasic calcium phosphate (BCP) and hydroxyapatite (HA) are investigated. After being steam sterilized in an autoclave (121 °C for 40 min), the porous bioceramics are dried and characterized. The steam sterilization has no obvious effects on the phase composition, thermal stability, pH value and dissolubility of β-TCP porous bioceramic, but changes its morphology and mechanical strength. Meanwhile, the steam sterilization leads to the significant changes of the morphology, phase composition, pH value and dissolubility of BCP porous bioceramic. The increase of dissolubility and mechanical strength, the decrease of pH value of the immersed solution and partial oriented growth of crystals are also observed in HA porous bioceramic after steam sterilization. These results indicate that the steam sterilization can result in different influences on the physicochemical properties of β-TCP, BCP and HA porous bioceramics, thus the application of the steam sterilization on the three kinds of Ca-P porous bioceramics should be considered carefully based on the above changed properties.

  7. Computational studies of bioceramic crystals and related materials

    Science.gov (United States)

    Rulis, Paul Michael

    Ongoing research to improve the foundations of knowledge concerning the human body requires a detailed understanding of the effects derived from atomic interactions. The details of these fundamental interactions will pave the way to the effective manipulation of macroscopic tissue. As a small step towards the realization of that goal the Orthogonalized Linear Combination of Atomic Orbitals (OLCAO) program suite has been applied to complex bioceramic crystals and other prototypes of hard tissue biological nanostructures. In addition, the OLCAO program suite has been further developed and extended in terms of efficiency, features, ease of use, and ease of maintenance such that even more complex systems and effects can be treated in the future. Through extensive OLCAO ab initio calculations on a collection of prototype bioceramic crystals the differences between them in terms of bonding, charge transfer, electronic structure, and spectroscopic properties have been detailed in an effort to lay the foundations of further research where interfaces, dopants, and defects are considered. In addition, inactive silicon defects that can be considered as prototypes for the complex environment in which bioceramic apatites exist have also been studied with the OLCAO program suite in an effort to expand the detection limit of small structures through spectroscopic means. With much effort, the OLCAO program suite has undergone a detailed conversion to a more modern programming language and programming style. A thorough review of the source code has accounted for many inaccuracies, corrected some programming errors, and removed various inefficient algorithmic bottlenecks. The generation of OLCAO input files, the execution of the components of the OLCAO suite, and the analysis of resultant data has been automated with numerous control scripts. Various external library packages have been instrumented for the benefit of profiling and resource efficiency in a high performance computing

  8. Successful commercialisation of locally fabricated bioceramics for clinical applications.

    Science.gov (United States)

    Fazan, F; Besar, I; Osman, A; Samsudin, A R; Khalid, K A

    2008-07-01

    This paper chronicled the development of a locally produced bone graft substitute based on calcium phosphate bioceramics called "GranuMaS--from concepts to clinics, and finally to its successful commercialization all within 5-year duration. It was a Prioritized Research (PR) collaborative project of 5 institutions namely SIRIM, ANM, USM, UKM and IIUM, funded by MOSTI to the amount of approximately RM2.5 millions under RM8. This paper also highlighted the requirements needed in terms of technical expertise/manpower, facilities and infrastructure, and government/institutional supports, as well as the challenge faced in developing and commercializing such product.

  9. LOW TEMPERATURE SINTERING OF ALUMINA BIOCERAMIC UNDER NORMAL PRESSURE

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    Superfine alumina powder with high purity (mean particle size is less than 0. 35μm) were used as main starting material for sintering alumina ceramic. A multiple additive MgO-ZrO2 (Y2O3) was homogeneously added into the batch by the chemical coprecipitation method. Sintering of alumina bioceramic at low tempera ture (<1600C) was achieved resulting in a dense and high strength alumina ceramic with the bending strength up to 382 MPa and an improved fracture toughness. Mechanism that the multiple additives promote the sintering of alumina ceramic is discussed on the base of XRD and SEM analysis.

  10. Bifunctional bioceramics stimulating osteogenic differentiation of a gingival fibroblast and inhibiting plaque biofilm formation.

    Science.gov (United States)

    Shen, Ya; Wang, Zhejun; Wang, Jiao; Zhou, Yinghong; Chen, Hui; Wu, Chengtie; Haapasalo, Markus

    2016-04-01

    Gingival recession is a common clinical problem that results in esthetic deficiencies and poor plaque control and predominantly occurs in aged patients. In order to restore the cervical region, ideal biomaterials should possess the ability to stimulate proliferation and osteogenesis/cementogenesis of human gingival fibroblasts (HGF) and have a strong antibiofilm effect. The aim of the present study was to investigate the interactions of HGF and oral multispecies biofilms with Ca, Mg and Si-containing bredigite (BRT, Ca7MgSi4O16) bioceramics. BRT extract induced osteogenic/cementogenic differentiation of HGF and its inhibition of plaque biofilm formation were systematically studied. BRT extract in concentrations lower than <200 mg mL(-1) presented high biocompatibility to HGF cells in 3 days. Ion extracts from BRT also stimulated a series of bone-related gene and protein expressions in HGF cells. Furthermore, BRT extract significantly inhibited oral multispecies plaque biofilm growth on its surface and contributed to over 30% bacterial cell death without additional antibacterial agents in two weeks. A planktonic killing test showed that BRT suppressed 98% plaque bacterial growth compared to blank control in 3 days. The results also revealed that BRT extract has an osteostimulation effect on HGF. The suppression effect on plaque biofilms suggested that BRT might be used as a bioactive material for cervical restoration and that the synergistic effect of bioactive ions, such as Ca, Mg and Si ions, played an important role in the design and construction of bifunctional biomaterials in combination with tissue regeneration and antibiofilm activity.

  11. Effect of silica on porosity, strength, and toughness of pressureless sintered calcium phosphate-zirconia bioceramics.

    Science.gov (United States)

    Schumacher, Thomas C; Treccani, Laura; Rezwan, Kurosch

    2015-08-12

    The preparation of dense, high-strength calcium phosphate-zirconia (CaP-ZrO2) composed bioceramics is realized via versatile pressureless sintering by adding silica nanoparticles. Two different weight ratios of HAp:ZrO2, 9:1 and 1:1, are used with varying silica contents from 5 to 20 wt%. After sintering at 1200 °C, the phase composition, microstructure, porosity, biaxial bending strength, and fracture toughness as well as SBF in vitro bioactivity are characterized. We show that the addition of silica altered the crystal phase composition, inhibiting the formation of non-favourable cubic ZrO2. Furthermore, SiO2 addition leads to an increase of the biaxial bending strength, and the fracture toughness of CaP-ZrO2-containing materials. With the addition of 20 wt% silica we find the highest characteristic strength (268 MPa) and toughness (2.3   ±   0.1 MPam(0.5)) at  <1% porosity. Both mechanical properties are 2 times higher than those of pure hydroxyapatite. At the same time we observe for the very same composition similar bioactivity to that of pure hydroxyapatite.

  12. Osseointegration of alumina bioceramic granules: A comparative experimental study

    Science.gov (United States)

    Rerikh, V. V.; Avetisyan, A. R.; Zaydman, A. M.; Anikin, K. A.; Bataev, V. A.; Nikulina, A. A.; Sadovoy, M. A.; Aronov, A. M.; Semantsova, E. S.

    2016-08-01

    To perform a comparative analysis of osseointegration of bioceramic alumina-based granules, hydroxyapatite-based granules, and deproteinized bone granules. The experiment was conducted on 52 adult male Kyoto-Wistar rats weighing 350 to 520 g. The animals were divided into five matched groups that differed only in the type of an implanted material. The granules were implanted in the lumbar vertebral bodies and in the distal right femur of each laboratory animal. Two months after surgery, the animals were euthanized, followed by tissue sampling for morphological studies. An examination of specimens from the groups with implanted alumina granules revealed the newly formed trabecular bone with remodeling signs. The bone tissue filled the intragranular space, tightly adhering to the granule surface. There was no connective tissue capsule on the border between bone tissue and alumina granules. Cylindrical bioceramic alumina-based granules with an open internal channel have a higher strength surpassing than that of analogs and the osseointegration ability close to that of hydroxyapatite and deproteinized bone granules.

  13. Calcium phosphate bioceramics induce mineralization modulated by proteins.

    Science.gov (United States)

    Wang, Kefeng; Leng, Yang; Lu, Xiong; Ren, Fuzeng

    2013-08-01

    Proteins play an important role in the process of biomineralization, which is considered the critical process of new bone formation. The calcium phosphate (Ca-P) mineralization happened on hydroxyapatite (HA), β-tricalcium phosphate (β-TCP) and biphasic calcium phosphate (BCP) when proteins presented were investigated systematically. The results reveal that the presence of protein in the revised simulated body fluid (RSBF) did not alter the shape and crystal structure of the precipitated micro-crystals in the Ca-P layer formed on the three types of bioceramics. However, the morphology of the Ca-P precipitates was regulated but the structure of Ca-P crystal was unchanged in vivo. The presence of proteins always inhibits Ca-P mineralization in RSBF and the degree of inhibitory effect is concentration dependent. Furthermore, Protein presence can increase the possibility of HA precipitation in vitro and in vivo. The results obtained in this study can be helpful for better understanding the mechanism of biomineralization induced by the Ca-P bioceramics.

  14. Medical applications of organic-inorganic hybrid materials within the field of silica-based bioceramics.

    Science.gov (United States)

    Vallet-Regí, María; Colilla, Montserrat; González, Blanca

    2011-02-01

    Research on bioceramics has evolved from the use of inert materials for mere substitution of living tissues towards the development of third-generation bioceramics aimed at inducing bone tissue regeneration. Within this context hybrid bioceramics have remarkable features resulting from the synergistic combination of both inorganic and organic components that make them suitable for a wide range of medical applications. Certain bioceramics, such as ordered mesoporous silicas, can exhibit different kind of interaction with organic molecules to develop different functions. The weak interaction of these host matrixes with drug molecules confined in the mesoporous channels allows these hybrid systems to be used as controlled delivery devices. Moreover, mesoporous silicas can be used to fabricate three (3D)-dimensional scaffolds for bone tissue engineering. In this last case, different osteoinductive agents (peptides, hormones and growth factors) can be strongly grafted to the bioceramic matrix to act as attracting signals for bone cells to promote bone regeneration process. Finally, recent research examples of organic-inorganic hybrid bioceramics, such as stimuli-responsive drug delivery systems and nanosystems for targeting of cancer cells and gene transfection, are also tackled in this tutorial review (64 references).

  15. [The effect of technological parameters of wide-band laser cladding on microstructure and sinterability of gradient bioceramics composite coating].

    Science.gov (United States)

    Liu, Qibin; Zhu, Weidong; Zou, Longjiang; Zheng, Min; Dong, Chuang

    2005-12-01

    The gradient bioceramics coating was prepared on the surface of Ti-6Al-4V alloy by using wide-band laser cladding. And the effect of technological parameters of wide-band laser cladding on microstructure and sinterability of gradient bioceramics composite coating was studied. The experimental results indicated that in the circumstances of size of laser doze D and scanning velocity V being fixed, with the increasement of power P, the density of microstructure in bioceramics coating gradually degraded; with the increasement of power P, the pore rate of bioceramics gradually became high. While P = 2.3 KW, the bioceramics coating with dense structure and lower pore rate (5.11%) was obtained; while P = 2.9 KW, the bioceramics coating with disappointing density was formed and its pore rate was up to 21.32%. The microhardness of bioceramics coating demonstrated that while P = 2.3 KW, the largest value of microhardness of bioceramics coating was 1100 HV. Under the condition of our research work, the optimum technological parameters for preparing gradient bioceramics coating by wide-band laser cladding are: P = 2.3 KW, V = 145 mm/min, D = 16 mm x 2 mm.

  16. New bio-ceramization processes applied to vegetable hierarchical structures for bone regeneration: an experimental model in sheep.

    Science.gov (United States)

    Filardo, Giuseppe; Kon, Elizaveta; Tampieri, Anna; Cabezas-Rodríguez, Rafael; Di Martino, Alessandro; Fini, Milena; Giavaresi, Gianluca; Lelli, Marco; Martínez-Fernández, Julian; Martini, Lucia; Ramírez-Rico, Joaquin; Salamanna, Francesca; Sandri, Monica; Sprio, Simone; Marcacci, Maurilio

    2014-02-01

    Bone loss is still a major problem in orthopedics. The purpose of this experimental study is to evaluate the safety and regenerative potential of a new scaffold based on a bio-ceramization process for bone regeneration in long diaphyseal defects in a sheep model. The scaffold was obtained by transformation of wood pieces into porous biomorphic silicon carbide (BioSiC®). The process enabled the maintenance of the original wood microstructure, thus exhibiting hierarchically organized porosity and high mechanical strength. To improve cell adhesion and osseointegration, the external surface of the hollow cylinder was made more bioactive by electrodeposition of a uniform layer of collagen fibers that were mineralized with biomimetic hydroxyapatite, whereas the internal part was filled with a bio-hybrid HA/collagen composite. The final scaffold was then implanted in the metatarsus of 15 crossbred (Merinos-Sarda) adult sheep, divided into 3 groups: scaffold alone, scaffold with platelet-rich plasma (PRP) augmentation, and scaffold with bone marrow stromal cells (BMSCs) added during implantation. Radiological analysis was performed at 4, 8, 12 weeks, and 4 months, when animals were sacrificed for the final radiological, histological, and histomorphometric evaluation. In all tested treatments, these analyses highlighted the presence of newly formed bone at the bone scaffolds' interface. Although a lack of substantial effect of PRP was demonstrated, the scaffold+BMSC augmentation showed the highest value of bone-to-implant contact and new bone growth inside the scaffold. The findings of this study suggest the potential of bio-ceramization processes applied to vegetable hierarchical structures for the production of wood-derived bone scaffolds, and document a suitable augmentation procedure in enhancing bone regeneration, particularly when combined with BMSCs.

  17. The Transformation of Calcium Phosphate Bioceramics in Vivo

    Institute of Scientific and Technical Information of China (English)

    DAI Hong-lian; CAO Xian-ying; LI Xiao-xi; YAN Yu-hua; LI Shi-pu

    2003-01-01

    To study the transformation process of calcium phosphate bioceramic in vivo,biodegradable porous β-tricalcium phosphate ceramics (β-TCP) were used in this experiment. The materials (φ5×8mm) were implanted in the tibia of rabbits. The β-TCP ceramics with bone tissue were retrieved and treated for histology, and then observed by using a scanning electron microscope (SEM) and an electron probe X-ray microanalyzer (EMPA) every month. The results show that β-TCP ceramics bond to bone directly,new bones are forming and maturing with materials continuous degrading,and the materials are nearly replaced by the formed bone finally.Parts of the materials were degraded,absorpted and recrystallized,the others dispersped on the cancellous bone and the Haversian lamella with an irregular arrangement incorporating in bone formation directly by remodeling structure.

  18. Three-dimensional laser-assisted processing of bioceramics

    Science.gov (United States)

    Comesaña, R.; Lusquiños, F.; del Val, J.; Malot, T.; Riveiro, A.; Quintero, F.; Boutinguiza, M.; Aubry, P.; Pou, J.

    The study of calcium phosphate bioceramics processing by rapid prototyping based on laser cladding was tackled in this work. This technique shows a great potential to provide a three-dimensional tailored implant adapted to the specific problem of each patient. Working window to produce stable geometrical features and repeatable microstructures was established by real time process monitoring and characterization of the processed material. The relationships between the processing parameters and the obtained properties are discussed, in addition to the biological behaviour of the produced parts. The obtained calcium phosphate phases (oxyapatite, tricalcium phosphate, tetracalcium phosphate and amorphous calcium phosphate) are found to favorably influence the degradability of the precursor hydroxyapatite in Tris-HCl buffer which is a good sign of the favorable behavior of this type of materials when implanted 'in vivo'.

  19. Bioceramics for Hip Joints: The Physical Chemistry Viewpoint

    Directory of Open Access Journals (Sweden)

    Giuseppe Pezzotti

    2014-06-01

    Full Text Available Which intrinsic biomaterial parameter governs and, if quantitatively monitored, could reveal to us the actual lifetime potential of advanced hip joint bearing materials? An answer to this crucial question is searched for in this paper, which identifies ceramic bearings as the most innovative biomaterials in hip arthroplasty. It is shown that, if in vivo exposures comparable to human lifetimes are actually searched for, then fundamental issues should lie in the physical chemistry aspects of biomaterial surfaces. Besides searching for improvements in the phenomenological response of biomaterials to engineering protocols, hip joint components should also be designed to satisfy precise stability requirements in the stoichiometric behavior of their surfaces when exposed to extreme chemical and micromechanical conditions. New spectroscopic protocols have enabled us to visualize surface stoichiometry at the molecular scale, which is shown to be the key for assessing bioceramics with elongated lifetimes with respect to the primitive alumina biomaterials used in the past.

  20. Thermoseeds for interstitial magnetic hyperthermia: from bioceramics to nanoparticles

    Science.gov (United States)

    Baeza, A.; Arcos, D.; Vallet-Regí, M.

    2013-12-01

    The development of magnetic materials for interstitial hyperthermia treatment of cancer is an ever evolving research field which provides new alternatives to antitumoral therapies. The development of biocompatible magnetic materials has resulted in new biomaterials with multifunctional properties, which are able to adapt to the complex scenario of tumoral processes. Once implanted or injected in the body, magnetic materials can behave as thermoseeds under the effect of AC magnetic fields. Magnetic bioceramics aimed to treat bone tumors and magnetic nanoparticles are among the most studied thermoseeds, and supply different solutions for the different scenarios in cancerous processes. This paper reviews some of the biomaterials used for bone cancer treatment and skeletal reinforcing, as well as the more complex topic of magnetic nanoparticles for intracellular targeting and hyperthermia.

  1. Nanofiber generation of hydroxyapatite and fluor-hydroxyapatite bioceramics.

    Science.gov (United States)

    Kim, Hae-Won; Kim, Hyoun-Ee

    2006-05-01

    In this study, we produced hydroxyapatite (HA) and fluor-hydroxyapatite (FHA) bioceramics as a novel geometrical form, the nanoscale fiber, for the biomedical applications. Based on the sol-gel precursors of the apatites, an electrospinning technique was introduced to generate nanoscale fibers. The diameter of the fibers was exploited in the range of a few micrometers to hundreds of nanometers (1.55 microm-240 nm) by means of adjusting the concentration of the sols. Through the fluoridation of apatite, the solubility of the fiber was tailored and the fluorine ions were well released from the FHA. The HA and FHA nanofibers produced in this study are considered to find potential applications in the biomaterials and tissue engineering fields.

  2. Effects of calcium phosphate bioceramics on skeletal muscle cells.

    Science.gov (United States)

    Sun, J S; Tsuang, Y H; Yao, C H; Liu, H C; Lin, F H; Hang, Y S

    1997-02-01

    With advances in ceramics technology, calcium phosphate bioceramics have been applied as bone substitutes. The effects of implants on bony tissue have been investigated. The effects upon adjacent skeletal muscles have not been determined. The focus of this work is to elucidate the biological effects of various calcium phosphate bioceramics on skeletal muscles. Four different kinds of powder of calcium phosphate biomaterials including beta-tricalcium phosphate (beta-TCP), hydroxyapatite (HA), beta-dicalcium pyrophosphate (beta-DCP) and sintered beta-dicalcium pyrophosphate (SDCP), were tested by myoblast cell cultures. The results were analyzed by cell count, cell morphology and concentration of transforming growth factor beta 1 (TGF-beta 1) in culture medium. The cell population and TGF-beta 1 concentration of the control sample increased persistently as the time of culture increased. The changes in cell population and TGF-beta 1 concentration in culture medium of the beta-TCP and HA were quite low in the first 3 days of culture, then increased gradually toward the seventh day. The changes in cell population and TGF-beta 1 concentration in culture medium of the silica, beta-DCP, and SDCP were quite similar. They were lower during the first day of culture but increased and reached that of the control medium after 7 days' culture. Most cells on B-TCP and HA diminished in size with radially spread, long pseudopods. We conclude that HA and beta-TCP are thought to have an inhibitory effect on growth of the myoblasts. The HA and beta-TCP may interfere with the repair and regeneration of injured skeletal muscle after orthopedic surgery.

  3. Preparation, characterization and in vitro dissolution behavior of porous biphasic α/β-tricalcium phosphate bioceramics.

    Science.gov (United States)

    Xie, Lu; Yu, Haiyang; Deng, Yi; Yang, Weizhong; Liao, Li; Long, Qin

    2016-02-01

    The ideal bone tissue engineering scaffolds are long-cherished with the properties of interconnected macroporous structures, adjustable degradation and excellent biocompatibility. Here, a series of porous α/β-tricalcium phosphate (α/β-TCP) biphasic bioceramics with different phase ratios of α-TCP and β-TCP were successfully synthesized by heating an amorphous calcium phosphate precursor. The chemical and morphological characterization showed that α- and β-TCP phases co-existed in the α/β-TCP bioceramics and they had interconnected pore structures with size between 200 and 500μm. The in vitro dissolution behavior and bioactivity of the dual α/β-TCP were also probed in static and dynamic SBF for the first time. The results revealed that α/β-TCP scaffolds had good in vitro bioactivity, as the formation of bone-like apatite layers was induced on the scaffolds after mineralization in SBF. Moreover, dissolution rate of α/β-TCP bioceramics in dynamic environment was higher than that under static condition. Compared with monophasic TCP ceramics, these porous α/β-TCP bioceramics displayed a tailored dissolution rate proportionate to the TCP content (α and β) in the materials. Further, the degradation profile of porous α/β-TCP was well-described by Avrami equation. The porous dual α/β-TCP bioceramics with controllable degradation behavior hold great potential to be applied in bone tissue engineering as bone substitutes.

  4. Bioinspired structure of bioceramics for bone regeneration in load-bearing sites.

    Science.gov (United States)

    Zhang, Faming; Chang, Jiang; Lu, Jianxi; Lin, Kaili; Ning, Congqin

    2007-11-01

    The major problem with the use of porous bioceramics as bone regeneration grafts is their weak mechanical strength, which has not been overcome to date. Here we described a novel way to solve this problem. Beta-tricalcium phosphate (beta-TCP) bioceramics with a bioinspired structure were designed and prepared with a porous cancellous core (porosity: 70-90%) inside and a dense compact shell (porosity: 5-10%) outside that mimics the characteristics of natural bone. They showed excellent mechanical properties, with a compressive strength of 10-80MPa and an elastic modulus of 180MPa-1.0GPa, which could be tailored by the dense/porous cross-sectional area ratio obeying the rule of exponential growth. The in vitro degradation of the bioinspired bioceramics was faster than that of dense bioceramics but slower than that of porous counterparts. The changes in mechanical properties of the bioinspired ceramics during in vitro degradation were also investigated. A concept of the bioinspired macrostructure design of natural bone was proposed which provided a simple but effective way to increase the mechanical properties of porous bioceramics for load-bearing bone regeneration applications. It should be readily applicable to other porous materials.

  5. Biocompatibility of a functionally graded bioceramic coating made by wide-band laser cladding.

    Science.gov (United States)

    Weidong, Zhu; Qibin, Liu; Min, Zheng; Xudong, Wang

    2008-11-01

    The application of plasma spray is the most popular method by which a metal-bioceramic surface composite can be prepared for the repair of biological hard-tissue, but this method has disadvantages. These disadvantages include poor coating-to-substrate adhesion, low mechanical strength, and brittleness of the coating. In the investigation described in this article, a gradient bioceramic coating was prepared on a Ti-6Al-4V titanium alloy surface using a gradient composite design and wide-band laser cladding techniques. Using a trilayer-structure composed of a substratum, an alloy and bioceramics, the coating was chemically and metallurgically bonded with the substratum. The coating, which contains beta-tricalcium phosphate and hydroxyapatite, showed favorable biocompatibility with the bone tissue and promoted in vivo osteogenesis.

  6. The Technology and Properties of Digital Double Pulse Electrodepositing Ni-HA Composite Coating of Bioceramics

    Institute of Scientific and Technical Information of China (English)

    DONG He-yan; WANG Zhou; SHI Gu-guizhi; FU Chuan-qi; CHEN Wei-rong; JIN Zhong-hong; LI Yan

    2004-01-01

    This article discusses and analyses the technology, the surface image, microstructure and ability of digital double pulse electrodepositing Ni-HA composite coatings of bioceramics made on 1Crl8Ni9Ti substrate by SEM ,XRD and so on. The results shows that ( 1 ) the HA particles exit in substrate uniformly; (2) XRD result shows that there are HA peaks at 78. 023 ° ,43. 246°and 73. 120°differently; (3) The microhardnees of the composite coatings is increased with the rise of content of HA particles, and on the same conditions the microhardnees value is greater than that of common non-pulse electrodepositing Ni-HA composite coatings of bioceramics. (4) The grain size of digital double pulse electrodepositing Ni-HA composite coatings of bioceramics is much thinner than that of common D. C.

  7. 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.

  8. Bioceramics of apatites: an option for bone regeneration; Bioceramica de apatitas: uma opcao para regeneracao ossea

    Energy Technology Data Exchange (ETDEWEB)

    Arxer, Eliana Alves; Almeida Filho, Edson de; Guastaldi, Antonio Carlos, E-mail: iarxer@iq.unesp.br [Universidade Estadual Paulista Julio de Mesquita Filho (UNESP), Araraquara, SP (Brazil). Instituto de Quimica

    2011-07-01

    The bioceramics of calcium phosphate called apatite, are widely used as material for bone replacement and regeneration, due to its similarity to the mineral component of bones and teeth. The apatites are biocompatible, bioactive and integrate with living tissue by the same active process of physiological bone remodeling. These bioceramics may be used in medical, dental and orthopedic applications. In this research, it was used the wet method for the synthesis of the powder and biomimetic method for coating the surface. The Solubility study was performed in the layer deposited, apatite, for possible application as a platform for inorganic drug delivery. The bioceramics were characterized by MEV, DRX, and EDS. The curves of solubility of apatite in coatings showed that the OCP phase had a higher rate of release in the short term (4 days) while the HA phase showed a gradual release throughout the experiment (16 days). (author)

  9. The Role of Bioceramics Coating in Dental Implant Reliability and Success

    Directory of Open Access Journals (Sweden)

    Mortazavi V

    2000-05-01

    Full Text Available Characterization of bioceramics coating and evaluation of the influence of kind of coating on"nthe implantation has been developed in recent years."nDifferent bioceramics coating like calcium phosphate, hydroxyapatite, fluorapatite and bioglass were"ncoated on dental and orthopedic implants. In-vitro and in-vivo experiments were done for evolution of"nimplant success and reliability and study of factors, which may influence the results."nResearches indicate that different bioceramic coating may affect the bone bonding mechanism."nBiodegredable calcium phosphate coating can be resorbed and be replaced with bone tissues."nHydroxyapatite cause earlier stabilization of dental implant in surrounding bone (biological fixation and"nreduce healing time. Bioglass can protect substrate and provide interfacial attachment to bone.

  10. Bioactivity and mineralization of hydroxyapatite with bioglass as sintering aid and bioceramics with Na{sub 3}Ca{sub 6}(PO{sub 4}){sub 5} and Ca{sub 5}(PO{sub 4}){sub 2}SiO{sub 4} in a silicate matrix

    Energy Technology Data Exchange (ETDEWEB)

    Demirkiran, Hande [Materials Science and Engineering Department, University of Texas at Arlington, Arlington, TX 76019 (United States); Mohandas, Arunesh; Dohi, Motokazi; Fuentes, Alonso; Nguyen, Kytai [Bioengineering Department, University of Texas at Arlington, Arlington, TX 76019 (United States); Aswath, Pranesh, E-mail: aswath@uta.edu [Materials Science and Engineering Department, University of Texas at Arlington, Arlington, TX 76019 (United States)

    2010-01-30

    Hydroxyapatite and Bioglass-45S5 were sintered together creating new ceramic compositions that yielded increased apatite deposition and osteoblast differentiation and proliferation in vitro compared to hydroxyapatite. The sintered products characterized by X-ray diffraction, revealed hydroxyapatite as the main phase when small quantities (1, 2.5 and 5 wt.%) of bioglass was added. Bioglass behaved as a sintering aid with {beta}-TCP (Ca{sub 3}(PO{sub 4}){sub 2}) being the minor phase. The amount of {beta}-TCP increased with the amount of bioglass added. In compositions with larger additions of bioglass (10 and 25 wt.%), new phases with compositions of calcium phosphate silicate (Ca{sub 5}(PO{sub 4}){sub 2}SiO{sub 4}) and sodium calcium phosphate (Na{sub 3}Ca{sub 6}(PO{sub 4}){sub 5}) were formed respectively within amorphous silicate matrices. In vitro cell culture studies of the ceramic compositions were examined using bone marrow stromal cell (BMSC). Cell proliferation and differentiation of bone marrow stromal cells into osteoblasts were determined by Pico Green DNA assays and alkaline phosphatase (ALP) activity, respectively. All hydroxyapatite-bioglass co-sintered ceramics exhibited larger cell proliferation compared to pure hydroxyapatite samples. After 6 days in cell culture, the ceramic with Ca{sub 5}(PO{sub 4}){sub 3}SiO{sub 4} in a silicate matrix formed by reacting hydroxyapatite with 10 wt.% bioglass exhibited the maximum proliferation of the BMSC's. The ALP activity was found to be largest in the ceramic with Na{sub 3}Ca{sub 6}(PO{sub 4}){sub 5} embedded in a silicate matrix synthesized by reacting hydroxyapatite with 25 wt.% bioglass.

  11. Novel Bioceramic Urethral Bulking Agents Elicit Improved Host Tissue Responses in a Rat Model

    DEFF Research Database (Denmark)

    Mann-Gow, Travis K; King, Benjamin J; El-Ghannam, Ahmed;

    2016-01-01

    Objectives. To test the physical properties and host response to the bioceramic particles, silica-calcium phosphate (SCPC10) and Cristobalite, in a rat animal model and compare their biocompatibility to the current clinically utilized urethral bulking materials. Material and Methods. The novel...... agents using a rat animal model and hard tissue histology techniques compared two newly developed bioactive ceramic particles to three of the currently used bulking agents. The local host tissue response and bulking effects of bioceramic particles were superior while also possessing a comparable safety...

  12. Sputter deposited bioceramic coatings: surface characterisation and initial protein adsorption studies using surface-MALDI-MS

    DEFF Research Database (Denmark)

    Boyd, A. R.; Burke, G. A.; Duffy, H.

    2011-01-01

    Protein adsorption onto calcium phosphate (Ca–P) bioceramics utilised in hard tissue implant applications has been highlighted as one of the key events that influences the subsequent biological response, in vivo. This work reports on the use of surface-matrix assisted laser desorption ionisation...... to a combination of growth factors and lipoproteins present in serum. From the data obtained here it is evident that surface-MALDI-MS has significant utility as a tool for studying the dynamic nature of protein adsorption onto the surfaces of bioceramic coatings, which most likely plays a significant role...

  13. [Study on hydrogen autotrophic denitrification of bio-ceramic reactor].

    Science.gov (United States)

    Chen, Dan; Wang, Hong-Yu; Song, Min; Yang, Kai; Liu, Chen

    2013-10-01

    Nitrate wastewater is processed in a bio-ceramic reactor based on hydrogen autotrophic denitrification. The implementation procedure of biological denitrification by hydrogen autotrophic denitrification was investigated. The effects of hydraulic retention time, influent nitrate load, influent pH, temperature and the amount of hydrogen were assessed throughout this trial. The results showed that the removal rate of NO-(3) -N was 94. 54% and 97. 47% when the hydraulic retention time was 24 h and 48 h, respectively. When the hydraulic retention time was in the range of 5-16 h, the removal rate gradually dropped with the shortening of the hydraulic retention time. When the influent NO-(3) -N concentration was low, with the increase in the influent NO-(3) -N concentration, the degradation rate also increased. The denitrification was inhibited when the NO-(3) -N concentration was higher than 110 mg.L-1. Neutral and alkaline environment was more suitable for the reactor. The reactor showed a wide range of temperature adaptation and the optimum temperature of the reactor was from 25 to 30 degrees C. When hydrogen was in short supply, the effect of denitrification was significantly reduced. These results indicated the specificity of hydrogen utilization by the denitrifying bacteria. The effluent nitrite nitrogen concentration was maintained at low levels during the operation.

  14. Fabrication of Bioceramic Bone Scaffolds for Tissue Engineering

    Science.gov (United States)

    Liu, Fwu-Hsing

    2014-10-01

    In this study, microhydroxyapatite and nanosilica sol were used as the raw materials for fabrication of bioceramic bone scaffold using selective laser sintering technology in a self-developed 3D Printing apparatus. When the fluidity of ceramic slurry is matched with suitable laser processing parameters, a controlled pore size of porous bone scaffold can be fabricated under a lower laser energy. Results shown that the fabricated scaffolds have a bending strength of 14.1 MPa, a compressive strength of 24 MPa, a surface roughness of 725 nm, a pore size of 750 μm, an apparent porosity of 32%, and a optical density of 1.8. Results indicate that the mechanical strength of the scaffold can be improved after heat treatment at 1200 °C for 2 h, while simultaneously increasing surface roughness conducive to osteoprogenitor cell adhesion. MTT method and SEM observations confirmed that bone scaffolds fabricated under the optimal manufacturing process possess suitable biocompatibility and mechanical properties, allowing smooth adhesion and proliferation of osteoblast-like cells. Therefore, they have great potential for development in the field of tissue engineering.

  15. Electrically active bioceramics: a review of interfacial responses.

    Science.gov (United States)

    Baxter, F R; Bowen, C R; Turner, I G; Dent, A C E

    2010-06-01

    Electrical potentials in mechanically loaded bone have been implicated as signals in the bone remodeling cycle. Recently, interest has grown in exploiting this phenomenon to develop electrically active ceramics for implantation in hard tissue which may induce improved biological responses. Both polarized hydroxyapatite (HA), whose surface charge is not dependent on loading, and piezoelectric ceramics, which produce electrical potentials under stress, have been studied in order to determine the possible benefits of using electrically active bioceramics as implant materials. The polarization of HA has a positive influence on interfacial responses to the ceramic. In vivo studies of polarized HA have shown polarized samples to induce improvements in bone ingrowth. The majority of piezoelectric ceramics proposed for implant use contain barium titanate (BaTiO(3)). In vivo and in vitro investigations have indicated that such ceramics are biocompatible and, under appropriate mechanical loading, induce improved bone formation around implants. The mechanism by which electrical activity influences biological responses is yet to be clearly defined, but is likely to result from preferential adsorption of proteins and ions onto the polarized surface. Further investigation is warranted into the use of electrically active ceramics as the indications are that they have benefits over existing implant materials.

  16. Kinetics of dissolution of calcium phosphate (Ca-P bioceramics

    Directory of Open Access Journals (Sweden)

    Lukas Brazda

    2008-06-01

    Full Text Available Hydroxyapatite (HAp and β-tricalcium phosphate (β-TCP are widely used bioceramics for surgical or dental applications. This paper is dealing with dissolution kinetics of synthetically prepared β-TCP and four types of HAp granules. Two groups of HAp, treated at different temperatures, each of them with two different granule sizes, were tested. Three corrosive solutions with different pH and simulated body fluid (SBF were used for immersing of the samples. Changes in concentrations of calcium and phosphate ions, pH level and weight changes of the samples were observed. It was found that presence of TRIS buffer enhanced dissolution rate of the β-TCP approximately two times. When exposed to SBF solution, calcium phosphate (most probably hydroxyapatite precipitation predominates over β-TCP dissolution. Results from HAp samples dissolution showed some unexpected findings. Neither heat treatment nor HAp particle size made any major differences in dissolution rate of the same mass of each HAp sample.

  17. [Research on the mechanical properties of bone scaffold reinforced by magnesium alloy/bioceramics composite with stereolithography double channels].

    Science.gov (United States)

    Li, Changhai; Lian, Qin; Zhuang, Pei; Wang, Junzhong; Li, Dichen

    2015-02-01

    Focusing on the poor mechanical strength of porous bioceramics bone scaffold, and taking into account of the good mechanical properties of biodegradable magnesium alloy, we proposed a novel method to fabricate magnesium alloy/bioceramics composite bone scaffold with stereolithography double channels. Firstly, a scaffold structure without mutually connected double channels was designed. Then, an optimized bioceramics scaffold was fabricated according to stereolithography and gel-casing. Molten AZ31 magnesium alloy was perfused into the secondary channel of scaffold by low-pressure casting, and magnesium alloy/bioceramics composite bone scaffold was obtained when magnesium alloy was solidified. The compression test showed that the strength of bioceramics scaffold with only one channel and without magnesium alloy was (9.76 ± 0.64) MPa, while the strength of magnesium alloy/bioceramics composite scaffold with double channels was (17.25 ± 0.88) MPa. It can be concluded that the magnesium alloy/bioceramics composite is obviously able to improve the scaffold strength.

  18. Synthesis of calcium-phosphate and chitosan bioceramics for bone regeneration

    Directory of Open Access Journals (Sweden)

    FINISIE MELLATIE R.

    2001-01-01

    Full Text Available Bioceramic composites were obtained from chitosan and hydroxyapatite pastes synthesized at physiological temperature according to two different syntheses approaches. Usual analytical techniques (X-ray diffraction analysis, Fourier transformed infrared spectroscopy, Thermo gravimetric analysis, Scanning electron microscopy, X-ray dispersive energy analysis and Porosimetry were employed to characterize the resulting material. The aim of this investigation was to study the bioceramic properties of the pastes with non-decaying behavior from chitosan-hydroxyapatite composites. Chitosan, which also forms a water-insoluble gel in the presence of calcium ions, and has been reported to have pharmacologically beneficial effects on osteoconductivity, was added to the solid phase of the hydroxyapatite powder. The properties exhibited by the chitosan-hydroxyapatite composites were characteristic of bioceramics applied as bone substitutes. Hydroxyapatite contents ranging from 85 to 98% (w/w resulted in suitable bioceramic composites for bone regeneration, since they showed a non-decaying behavior, good mechanical properties and suitable pore sizes.

  19. Comparative characteristics of porous bioceramics for an osteogenic response in vitro and in vivo.

    Science.gov (United States)

    Lee, Hye-Rim; Kim, Han-Jun; Ko, Ji-Seung; Choi, Yong-Suk; Ahn, Myun-Whan; Kim, Sukyoung; Do, Sun Hee

    2013-01-01

    Porous calcium phosphate ceramics are used in orthopedic and craniofacial applications to treat bone loss, or in dental applications to replace missing teeth. The implantation of these materials, however, does not induce stem cell differentiation, so suitable additional materials such as porous calcium phosphate discs are needed to influence physicochemical responses or structural changes. Rabbit adipose-derived stem cells (ADSC) and mouse osteoblastic cells (MC3T3-E1) were evaluated in vitro by the MTT assay, semi-quantitative RT-PCR, and immunoblotting using cells cultured in medium supplemented with extracts from bioceramics, including calcium metaphosphate (CMP), hydroxyapatite (HA) and collagen-grafted HA (HA-col). In vivo evaluation of the bone forming capacity of these bioceramics in rat models using femur defects and intramuscular implants for 12 weeks was performed. Histological analysis showed that newly formed stromal-rich tissues were observed in all the implanted regions and that the implants showed positive immunoreaction against type I collagen and alkaline phosphatase (ALP). The intramuscular implant region, in particular, showed strong positive immunoreactivity for both type I collagen and ALP, which was further confirmed by mRNA expression and immunoblotting results, indicating that each bioceramic material enhanced osteogenesis stimulation. These results support our hypothesis that smart bioceramics can induce osteoconduction and osteoinduction in vivo, although mature bone formation, including lacunae, osteocytes, and mineralization, was not prominent until 12 weeks after implantation.

  20. Functional hydroxyapatite bioceramics with excellent osteoconductivity and stern-interface induced antibacterial ability.

    Science.gov (United States)

    Shi, Chao; Gao, Jianyong; Wang, Ming; Shao, Yiran; Wang, Liping; Wang, Dalin; Zhu, Yingchun

    2016-04-01

    The biocompatibility and antibacterial properties of hydroxyapatite (HAp) bioceramics are crucial in medical applications. However, it is still a challenge to control HAp with antibacterial ability while maintaining other biological properties in the development of bioactive bone implants. Herein, we report functional silver ion substituted HAp bioceramics with excellent osteoconductivity and efficient antibacterial activity and propose a stern-interface induced antibacterial mechanism of such bioactive ceramics. In this antibacterial process, the concentration of Ag(+) at the stern-interface of Ag/HAp bioceramics is nearly 5 times higher than that in the bulk solution due to the trace dopant Ag(+) enrichment in the stern layer of the electric double layer at the negatively charged surface of Ag/HAp bioceramics. Trace Ag-doping in HAp induces a positive shift of zeta potential and increase of hydrophilicity, which may help inhibit bacterial proliferation. The positive osteoblast adhesion, proliferation and differentiation of ultra-trace doped Ag/HAp are also demonstrated through actin cytoskeleton staining, MTT and alkaline phosphatase (ALP) activity assays. This work may enlighten us on the artificial design of novel smart anti-infective bone grafts using ultra-trace functional elements and also suggest its potential applications in orthopedic surgery and bone osseointegration.

  1. Tailoring the nanostructured surfaces of hydroxyapatite bioceramics to promote protein adsorption, osteoblast growth, and osteogenic differentiation.

    Science.gov (United States)

    Lin, Kaili; Xia, Lunguo; Gan, Jingbo; Zhang, Zhiyuan; Chen, Hong; Jiang, Xinquan; Chang, Jiang

    2013-08-28

    To promote and understand the biological responses of the implant via nanostructured surface design is essential for the development of bioactive bone implants. However, the control of the surface topography of the bioceramics in nanoscale is a big challenge because of their brittle property. Herein, the hydroxyapatite (HAp) bioceramics with distinct nanostructured topographies were fabricated via hydrothermal treatment using α-tricalcium phosphate ceramic as hard-template under different reaction conditions. HAp bioceramics with nanosheet, nanorod and micro-nanohybrid structured surface in macroscopical size were obtained by controlling the composition of the reaction media. Comparing with the traditional sample with flat and dense surface, the fabricated HAp bioceramics with hierarchical 3D micro-nanotextured surfaces possessed higher specific surface area, which selectively enhanced adsorption of specific proteins including Fn and Vn in plasma, and stimulated osteoblast adhesion, growth, and osoteogenic differentiation. In particular, the biomimetic features of the hierarchical micro-nanohybrid surface resulted in the best ability for simultaneous enhancement of protein adsorption, osteoblast proliferation, and differentiation. The results suggest that the hierarchical micro-nanohybrid topography might be one of the critical factors to be considered in the design of functional bone grafts.

  2. Comparative characteristics of porous bioceramics for an osteogenic response in vitro and in vivo.

    Directory of Open Access Journals (Sweden)

    Hye-Rim Lee

    Full Text Available Porous calcium phosphate ceramics are used in orthopedic and craniofacial applications to treat bone loss, or in dental applications to replace missing teeth. The implantation of these materials, however, does not induce stem cell differentiation, so suitable additional materials such as porous calcium phosphate discs are needed to influence physicochemical responses or structural changes. Rabbit adipose-derived stem cells (ADSC and mouse osteoblastic cells (MC3T3-E1 were evaluated in vitro by the MTT assay, semi-quantitative RT-PCR, and immunoblotting using cells cultured in medium supplemented with extracts from bioceramics, including calcium metaphosphate (CMP, hydroxyapatite (HA and collagen-grafted HA (HA-col. In vivo evaluation of the bone forming capacity of these bioceramics in rat models using femur defects and intramuscular implants for 12 weeks was performed. Histological analysis showed that newly formed stromal-rich tissues were observed in all the implanted regions and that the implants showed positive immunoreaction against type I collagen and alkaline phosphatase (ALP. The intramuscular implant region, in particular, showed strong positive immunoreactivity for both type I collagen and ALP, which was further confirmed by mRNA expression and immunoblotting results, indicating that each bioceramic material enhanced osteogenesis stimulation. These results support our hypothesis that smart bioceramics can induce osteoconduction and osteoinduction in vivo, although mature bone formation, including lacunae, osteocytes, and mineralization, was not prominent until 12 weeks after implantation.

  3. In vitro and in vivo evaluation of akermanite bioceramics for bone regeneration.

    Science.gov (United States)

    Huang, Yan; Jin, Xiaogang; Zhang, Xiaoling; Sun, Hongli; Tu, Jinwen; Tang, Tingting; Chang, Jiang; Dai, Kerong

    2009-10-01

    This study investigated the effects of a calcium magnesium silicate bioceramic (akermanite) for bone regeneration in vitro and in vivo, with beta-tricalcium phosphate (beta-TCP) as a control. In vitro, the human bone marrow-derived mesenchymal stromal cells (hBMSCs) were cultured in an osteogenic medium supplemented with a certain concentration of two bioceramics' extracts for 20 days. An MTT assay showed that akermanite extract promoted proliferation of hBMSC significantly more than did beta-TCP extract. The results of alkaline phosphatase (ALP) activity test and the expression of osteogenic marker genes such as ALP, osteopontin (OPN), osteocalcin (OCN) and bone sialoprotein (BSP) demonstrated that the osteogenic differentiation of hBMSC was enhanced more by akermanite extract than by beta-TCP extract. In vivo, a histomorphology analysis and histomorphometry of the two porous bioceramics implants in rabbit femur defect models indicated that both in early- and late-stage implantations, akermanite promoted more osteogenesis and biodegradation than did beta-TCP; and in late-stage implantations, the rate of new bone formation was faster in akermanite than in beta-TCP. These results suggest that akermanite might be a potential and attractive bioceramic for tissue engineering.

  4. Current perspectives of bio-ceramic technology in endodontics: calcium enriched mixture cement - review of its composition, properties and applications

    OpenAIRE

    Utneja, Shivani; Nawal, Ruchika Roongta; Talwar, Sangeeta; Verma, Mahesh

    2014-01-01

    Advancements in bio-ceramic technology has revolutionised endodontic material science by enhancing the treatment outcome for patients. This class of dental materials conciliates excellent biocompatibility with high osseoconductivity that render them ideal for endodontic care. Few recently introduced bio-ceramic materials have shown considerable clinical success over their early generations in terms of good handling characteristics. Calcium enriched mixture (CEM) cement, Endosequence sealer, a...

  5. Oxide-bioceramic coatings obtained on titanium items by the induction heat treatment and modified with hydroxyapatite nanoparticles

    Science.gov (United States)

    Fomin, Aleksandr A.; Fomina, Marina A.; Rodionov, Igor V.; Koshuro, Vladimir A.; Petrova, Natalia V.; Skaptsov, Aleksandr A.; Atkin, Vsevolod S.

    2015-06-01

    Prospective composite bioceramic titania coatings were obtained on intraosseous implants fabricated from cp-titanium and medical titanium alloy VT16 (Ti-2.5Al-5Mo-5V). Consistency changes of morphological characteristics, mechanical properties and biocompatibility of experimental titanium implant coatings obtained by oxidation during induction heat treatment are defined. Technological recommendations for obtaining bioceramic coatings with extremely high strength on titanium items surface are given.

  6. Surface analysis applied to metal-ceramic and bioceramic interfacial bonding

    Energy Technology Data Exchange (ETDEWEB)

    Smart, R.St.C.; Arora, P.S.; Steveson, M.; Kawashima, N.; Cavallaro, G.P.; Ming, H.; Skinner, W.M. [University of South Australia, Mawson Lakes, Adelaide, SA (Australia). Ian Wark Research Institute

    1999-12-01

    Full text: Low temperature plasma reactions, combined with sol-gel coatings, have been used to produce a variety of ceramic surface layers on metal substrates and interfacial layers between metals and oxides or other ceramics. These layers can be designed to be compositionally and functionally graded from the metal to bulk ceramic material, eg. silica, alumina, hydroxyapatite. The graded layers are generally <50nm thick, continuous, fully bonded to the substrate and deformable without disbonding. The objectives in design of these layers have been to produce: metal surfaces protected from oxidation, corrosion and acid attack; improved metal-ceramic bonding; and bioceramic titanium-based interfaces to bioactive hydroxyapatite for improved dental and medical implants. Modified Auger parameter studies for Si in XPS spectra show that the structure on the metal surfaces grades from amorphous, dehydroxylated silica on the outer surface through layer silicates, chain silicates, pyrosilicates to orthosilicates close to the metal interface. At the metal interface, detached grains of the metal are imaged with interpenetration of the oxide and silicate species linking the layer to the oxidised metal surface. The {approx}30nm layer has a substantially increased frictional load compared with the untreated oxidised metal, i.e. behaviour consistent with either stronger adhesion of the coating to the substrate or a harder surface. The composition, structure and thickness of these layers can be controlled by the duration of each plasma reaction and the choice of the final reagent. The mechanisms of reaction in each process step have been elucidated with a combination of XPS, TOF-SIMS, TEM, SEM and FTIR. Similar, graded titanium/oxide/silicate/silica ceramic surface layers have been shown to form using the low temperature plasma reactions on titanium alloys used in medical and dental implants. Thicker (i.e. {mu}m) overlayers of ceramic materials can be added to the graded surface

  7. The Effects of Solid Phase Additives on Sintering Properties of Alumina Bioceramic

    Institute of Scientific and Technical Information of China (English)

    WANG Xin-yu; LI Shi-pu; HE Jian-hua; JIANG Xin; LI Jian-hua

    2003-01-01

    In order to reduce the sintering temperature and improve the preparing conditions of alumina bioceramics,the Mg-Zr-Y composite solid phase additives were added into high purity Al2O3 micro-powder by chemical coprecipitation method.The powder was shaped under 200MPa cold isostatic pressure,and then the biscuits were sintered at 1600℃ under normal pressure.The sintered alumina materials were tested and the sintering mechanism was discussed.The results show that physical properties of the material were improved comparatively.The Mg-Zr-Y composite solid additives could promote the sintering of alumina bioceramics and the mechanism is solid phase sintering.

  8. Trend report on international and Japanese standardization activities for bioceramics and tissue engineered medical products.

    Science.gov (United States)

    Tsutsumi, Sadami

    2010-02-01

    Since porous and injectable bioceramics have recently been utilized often as scaffolds for bone regenerative medicine, the need for their standardization has increased. One of the standard proposals in ISO/TC150 and JIS has been a draft for characterization of the porous bioceramic scaffolds in both micro- and macro-scopic aspects. ISO/TC150/SC7 (Tissue engineered medical products) has been co-chaired by Professor J E Lemons, Department of Surgery, University of Alabama at Birmingham and Dr R Nakaoka, Division of Medical Devices, National Institute of Health Sciences, Japan. The scope of SC7 has been specified as 'Standardization for the general requirements and performance of tissue engineered medical products with the exclusion of gene therapy, transplantation and transfusion'.

  9. Trend report on international and Japanese standardization activities for bioceramics and tissue engineered medical products

    Directory of Open Access Journals (Sweden)

    Sadami Tsutsumi

    2010-01-01

    Full Text Available Since porous and injectable bioceramics have recently been utilized often as scaffolds for bone regenerative medicine, the need for their standardization has increased. One of the standard proposals in ISO/TC150 and JIS has been a draft for characterization of the porous bioceramic scaffolds in both micro- and macro-scopic aspects. ISO/TC150/SC7 (Tissue engineered medical products has been co-chaired by Professor J E Lemons, Department of Surgery, University of Alabama at Birmingham and Dr R Nakaoka, Division of Medical Devices, National Institute of Health Sciences, Japan. The scope of SC7 has been specified as 'Standardization for the general requirements and performance of tissue engineered medical products with the exclusion of gene therapy, transplantation and transfusion'.

  10. Polyfunctional bioceramics modified by M-type hexagonal ferrite particles for medical applications

    Science.gov (United States)

    Tkachenko, M. V.; Ol'Khovik, L. P.; Kamzin, A. S.

    2011-06-01

    Magnetic bioceramics based on Ca5(PO4)3OH hydroxyapatite and M-type hexagonal ferrite (HF) microcrystals has been synthesized and characterized. The material consists of a biocompatible apatite matrix containing dispersed M-type HF particles. The latter component makes the magnetic characteristics of synthesized ceramics significantly higher as compared to those of iron-oxide-modified bioglass ceramics currently used in medicine. These properties increase the efficiency and prospects of using the new bioceramics in medicine, in particular, for the hyperthermal treatment of malignant tumors. Thus, a new class of materials is created, which combine the necessary biocompatibility and biological activity of Ca5(PO4)3OH hydroxyapatite and high magnetic characteristics of M-type HF microcrystals.

  11. Zinc-modified calcium silicate bioceramics coating and osteointegration%锌修饰硅酸钙陶瓷涂层与骨整合

    Institute of Scientific and Technical Information of China (English)

    徐立璋; 余将明; 叶晓健; 李恺; 郑学斌; 唐峰; 许鹏; 席焱海; 许国华; 侯春林

    2016-01-01

    BACKGROUND:Zinc-modified calcium silicate (CaSiO3) bioceramics coating on the titanium surface prepared in preliminary experiments has good chemical stability and antibacterial property. OBJECTIVE:To observe the effects of zinc-modified CaSiO3 bioceramics coating on osteointegration. METHODS:MC3T3-E1 cels were respectively cultured on the titanium with zinc-modified CaSiO3 bioceramics coating (experiment group), titanium with CaSiO3 bioceramics coating (control group) and pure titanium (blank control group). Then, cel adhesion, proliferation, calcification rate and the expression of type I colagen and osteocalcin were detected. The implant materials mentioned above were respectively inserted into the femurs of New Zealand white rabbits, and after 1.5 months, the osteoproliferation and osteointegration between the implants and the host were tested. RESULTS AND CONCLUSION:In vitro experiment: The number of adhesive cels at 12 hours after co-culture was significantly increased in the experimental group compared with the control group and blank control group (P < 0.05). At 14 days after co-culture, cel proliferation ability and ability of calcium nodule formation in the experiment group were significantly better than those in the other groups (P < 0.05). At 21 days after co-culture, there was no significant difference in the expression of type I colagen, but the expression of osteocalcin in the experiment group was higher than that in the control group and blank control group (P < 0.05).In vivo experiment: In the experiment group, a large amount of bone substances were detected, the coating materials directly contacted with the bone interface, new bone tissues and little fibrous tissues were observed at the interface. In contrast, there was a small amount of bone hyperplasia in the control group and almost no bone hyperplase in the blank control group. Moreover, a small part of the implant directly contacted with the bone interface and the most part was separated from

  12. Three-Dimensional Printing of Hollow-Struts-Packed Bioceramic Scaffolds for Bone Regeneration.

    Science.gov (United States)

    Luo, Yongxiang; Zhai, Dong; Huan, Zhiguang; Zhu, Haibo; Xia, Lunguo; Chang, Jiang; Wu, Chengtie

    2015-11-01

    Three-dimensional printing technologies have shown distinct advantages to create porous scaffolds with designed macropores for application in bone tissue engineering. However, until now, 3D-printed bioceramic scaffolds only possessing a single type of macropore have been reported. Generally, those scaffolds with a single type of macropore have relatively low porosity and pore surfaces, limited delivery of oxygen and nutrition to surviving cells, and new bone tissue formation in the center of the scaffolds. Therefore, in this work, we present a useful and facile method for preparing hollow-struts-packed (HSP) bioceramic scaffolds with designed macropores and multioriented hollow channels via a modified coaxial 3D printing strategy. The prepared HSP scaffolds combined high porosity and surface area with impressive mechanical strength. The unique hollow-struts structures of bioceramic scaffolds significantly improved cell attachment and proliferation and further promoted formation of new bone tissue in the center of the scaffolds, indicating that HSP ceramic scaffolds can be used for regeneration of large bone defects. In addition, the strategy can be used to prepare other HSP ceramic scaffolds, indicating a universal application for tissue engineering, mechanical engineering, catalysis, and environmental materials.

  13. A comparative biomechanical study of bone ingrowth in two porous hydroxyapatite bioceramics

    Science.gov (United States)

    Ren, Li-Mei; Todo, Mitsugu; Arahira, Takaaki; Yoshikawa, Hideki; Myoui, Akira

    2012-12-01

    Calcium phosphate-based bioceramics have been widely used as artificial bone substitute materials because of their superior biocompatibility and osteoconductivity. In the present study, mechanical properties changes of two hydroxyapatite (HA) ceramics induced by bone ingrowth were tested and evaluated in a rabbit model. Both materials (NEOBONE®, Apaceram-AX®) have highly interconnected pores with a porosity of 75-85%. The major structural difference between them lies in that Apaceram-AX® has micropores smaller than 10 micrometers in diameter, whereas NEOBONE® does not contain such micropores. Both materials were implanted into the femoral condyles of rabbits for the specified observation period (1, 5, 12, 24, and 48 weeks) and then evaluated by experimental approach in combination with finite element method (FEM). Results indicate that two porous bioceramics exhibit different degradability in vivo, and remarkably different variation of total stiffness, elastic modulus distribution, as well as strain energy density distribution calculated by FE simulation. These results demonstrate how the internal microstructures affect the progress of bone regeneration and mechanical properties with the duration of implantation, emphasizing the importance of biomaterial design tailored to various clinic applications. Additionally, this study showed a potential for applying the computational method to monitor the time-dependent biomechanical changes of implanted porous bioceramics.

  14. Poly-cyclodextrin functionalized porous bioceramics for local chemotherapy and anticancer bone reconstruction.

    Science.gov (United States)

    Chai, Feng; Abdelkarim, Mohamed; Laurent, Thomas; Tabary, Nicolas; Degoutin, Stephanie; Simon, Nicolas; Peters, Fabian; Blanchemain, Nicolas; Martel, Bernard; Hildebrand, Hartmut F

    2014-08-01

    The progress in bone cancer surgery and multimodal treatment concept achieve only modest improvement in the overall survival, due to failure in clearing out residual cancer cells at the surgical margin and extreme side-effects of adjuvant postoperative treatments. Our study aims to propose a new method based on cyclodextrin polymer (polyCD) functionalized hydroxyapatite (HA) for achieving a high local drug concentration with a sustained release profile and a better control of residual malignant cells via local drug delivery and promotion of the reconstruction of bone defects. PolyCD, a versatile carrier for therapeutic molecules, can be incorporated into HA (bone regeneration scaffold) through thermal treatment. The parameters of polyCD treatment on the macroporous HA (porosity 65%) were characterized via thermogravimetric analysis. Good cytocompatibility of polyCD functionalized bioceramics was demonstrated on osteoblast cells by cell vitality assay. An antibiotic (gentamicin) and an anticancer agent (cisplatin) were respectively loaded on polyCD functionalized bioceramics for drug release test. The results show that polyCD functionalization leads to significantly improved drug loading quantity (30% more concerning gentamicin and twice more for cisplatin) and drug release duration (7 days longer concerning gentamicin and 3 days longer for cisplatin). Conclusively, this study offers a safe and reliable drug delivery system for bioceramic matrices, which can load anticancer agents (or/and antibiotics) to reduce local recurrence (or/and infection).

  15. [The effect of a simulated inflammation procedure in simulated body fluid on bone-like apatite formation on porous HA/beta-TCP bioceramics].

    Science.gov (United States)

    Ji, Jingou; Ran, Junguo; Gou, Li; Wang, Fangfu; Sun, Luwei

    2004-08-01

    The formation of bone-like apatite on porous HA/beta-TCP bioceramics in dynamic simulated body fluid (SBF) undergoing a simulated inflammation procedure (pH = 6.5) was investigated in order to study the mechanism of osteoinduction and build a new method to choose biomaterials with better bioactivity. The results showed that the surface of porous HA/beta-TCP bioceramics which underwent a simulated inflammation procedure in dynamic SBF was more smooth. The light acidity in the simulated inflammation procedure would dissolve the fine grains and the parts possessing smaller curvature radius on the surface of porous HA/beta-TCP bioceramics, which would reduce the bioceramics solubility. Followed in normal SBF (pH = 7.4), the amount of bone-like apatite formed on the porous HA/beta-TCP bioceramics was less than that of porous HA/beta-TCP bioceramics incubation in normal SBF all along. The results also showed that the amount of bone-like apatite formed on the porous HA/beta-TCP bioceramics sintered by a microwave plasma was more than that of porous HA/beta-TCP bioceramics sintered by a conventional furnace.

  16. The effect of autoclaving on the physical and biological properties of dicalcium phosphate dihydrate bioceramics: brushite vs. monetite.

    Science.gov (United States)

    Tamimi, Faleh; Le Nihouannen, Damien; Eimar, Hazem; Sheikh, Zeeshan; Komarova, Svetlana; Barralet, Jake

    2012-08-01

    Dicalcium phosphate dihydrate (brushite) is an osteoconductive biomaterial with great potential as a bioresorbable cement for bone regeneration. Preset brushite cement can be dehydrated into dicalcium phosphate anhydrous (monetite) bioceramics by autoclaving. This heat treatment results in changes in the physical characteristics of the material, improving in vivo bioresorption. This property is a great advantage in bone regeneration; however, it is not known how autoclaving brushite preset cement might improve its capacity to regenerate bone. This study was designed to compare brushite bioceramics with monetite bioceramics in terms of physical characteristics in vitro, and in vivo performance upon bone implantation. In this study we observed that monetite bioceramics prepared by autoclaving preset brushite cements had higher porosity, interconnected porosity and specific surface area than their brushite precursors. In vitro cell culture experiments revealed that bone marrow cells expressed higher levels of osteogenic genes Runx2, Opn, and Alp when the cells were cultured on monetite ceramics rather than on brushite ones. In vivo experiments revealed that monetite bioceramics resorbed faster than brushite ones and were more infiltrated with newly formed bone. In summary, autoclaving preset brushite cements results in a material with improved properties for bone regeneration procedures.

  17. Three-Dimensional Molding Based on Microstereolithography Using Beta-Tricalcium Phosphate Slurry for the Production of Bioceramic Scaffolds

    Science.gov (United States)

    Torii, Takashi; Inada, Makoto; Maruo, Shoji

    2011-06-01

    We report on a three-dimensional (3D) molding technique of fabricating bioceramic scaffolds. In this method, ceramic slurry is cast into a 3D polymer master mold, which is fabricated via microstereolithography, by a centrifugal casting method. The polymer master mold is thermally decomposed, so that a complex 3D bioceramic scaffold can be produced. In experiments, the decomposition process of the polymer model was optimized by the master decomposition curve theory to reduce harmful cracks in a green body. As a result, we could produce not only precise lattice models but also a sophisticated porous scaffold using beta-tricalcium phosphate (β-TCP) slurry. This bioceramic 3D molding technique based on microstereolithography will be useful for tailor-made tissue engineering and regeneration medicine.

  18. Controlling E. coli adhesion on high-k dielectric bioceramics films using poly(amino acid) multilayers.

    Science.gov (United States)

    Lawrence, Neil J; Wells-Kingsbury, Jamie M; Ihrig, Marcella M; Fangman, Teresa E; Namavar, Fereydoon; Cheung, Chin Li

    2012-03-06

    The influence of high-k dielectric bioceramics with poly(amino acid) multilayer coatings on the adhesion behavior of Escherichia coli (E. coli) was studied by evaluating the density of bacteria coverage on the surfaces of these materials. A biofilm forming K-12 strain (PHL628), a wild-type strain (JM109), and an engineered strain (XL1-Blue) of E. coli were examined for their adherence to zirconium oxide (ZrO(2)) and tantalum oxide (Ta(2)O(5)) surfaces functionalized with single and multiple layers of poly(amino acid) polyelectrolytes made by the layer-by-layer (LBL) deposition. Two poly(amino acids), poly(l-arginine) (PARG) and poly(l-aspartic acid) (PASP), were chosen for the functionalization schemes. All three strains were found to grow and preferentially adhere to bare bioceramic film surfaces over bare glass slides. The bioceramic and glass surfaces functionalized with positively charged poly(amino acid) top layers were observed to enhance the adhesion of these bacteria by up to 4-fold in terms of bacteria surface coverage. Minimal bacteria coverage was detected on surfaces functionalized with negatively charged poly(amino acid) top layers. The effect of different poly(amino acid) coatings to promote or minimize bacterial adhesion was observed to be drastically enhanced with the bioceramic substrates than with glass. Such observed enhancements were postulated to be attributed to the formation of higher density of poly(amino acids) coatings enabled by the high dielectric strength (k) of these bioceramics. The multilayer poly(amino acid) functionalization scheme was successfully applied to utilize this finding for micropatterning E. coli on bioceramic thin films.

  19. Evaluation of the interface between bone and titanium surfaces being blasted by aluminium oxide or bioceramic particles.

    Science.gov (United States)

    Müeller, Wolf-Dieter; Gross, Ulrich; Fritz, Thomas; Voigt, Christian; Fischer, Peter; Berger, Georg; Rogaschewski, Sigfried; Lange, Klaus-Peter

    2003-06-01

    The surface structure, in particular the surface roughness, and the surface chemistry of titanium implants influence their anchoring in bone. The aim of this study was to analyse metal-bone contact (MBC) after modification of the implant surface, using different materials for blasting. The surface modification of titanium was produced by blasting it with particles made of Al2O3 or bioceramics. The biological effects were then investigated experimentally using 27 rabbits, analysed after 7, 28 and 84 days after the implantation of titanium cylinders treated accordingly. The MBC showed a tendency for more bone after bioceramics were used as a blasting material, compared to Al2O3.

  20. Ultrasonic Vibration Assisted Grinding of Bio-ceramic Materials: Modeling, Simulation, and Experimental Investigations on Edge Chipping

    Science.gov (United States)

    Tesfay, Hayelom D.

    Bio-ceramics are those engineered materials that find their applications in the field of biomedical engineering or medicine. They have been widely used in dental restorations, repairing bones, joint replacements, pacemakers, kidney dialysis machines, and respirators. etc. due to their physico-chemical properties, such as excellent corrosion resistance, good biocompatibility, high strength and high wear resistance. Because of their inherent brittleness and hardness nature they are difficult to machine to exact sizes and dimensions. Abrasive machining processes such as grinding is one of the most widely used manufacturing processes for bioceramics. However, the principal technical challenge resulted from these machining is edge chipping. Edge chipping is a common edge failure commonly observed during the machining of bio-ceramic materials. The presence of edge chipping on bio-ceramic products affects dimensional accuracy, increases manufacturing cost, hider their industrial applications and causes potential failure during service. To overcome these technological challenges, a new ultrasonic vibration-assisted grinding (UVAG) manufacturing method has been developed and employed in this research. The ultimate aim of this study is to develop a new cost-effective manufacturing process relevant to eliminate edge chippings in grinding of bio-ceramic materials. In this dissertation, comprehensive investigations will be carried out using experimental, theoretical, and numerical approaches to evaluate the effect of ultrasonic vibrations on edge chipping of bioceramics. Moreover, effects of nine input variables (static load, vibration frequency, grinding depth, spindle speed, grinding distance, tool speed, grain size, grain number, and vibration amplitude) on edge chipping will be studied based on the developed models. Following a description of previous research and existing approaches, a series of experimental tests on three bio-ceramic materials (Lava, partially fired Lava

  1. Effect of micro-nano-hybrid structured hydroxyapatite bioceramics on osteogenic and cementogenic differentiation of human periodontal ligament stem cell via Wnt signaling pathway.

    Science.gov (United States)

    Mao, Lixia; Liu, Jiaqiang; Zhao, Jinglei; Chang, Jiang; Xia, Lunguo; Jiang, Lingyong; Wang, Xiuhui; Lin, Kaili; Fang, Bing

    2015-01-01

    The surface structure of bioceramic scaffolds is crucial for its bioactivity and osteoinductive ability, and in recent years, human periodontal ligament stem cells have been certified to possess high osteogenic and cementogenic differential ability. In the present study, hydroxyapatite (HA) bioceramics with micro-nano-hybrid surface (mnHA [the hybrid of nanorods and microrods]) were fabricated via hydrothermal reaction of the α-tricalcium phosphate granules as precursors in aqueous solution, and the effects of mnHA on the attachment, proliferation, osteogenic and cementogenic differentiations of human periodontal ligament stem cells as well as the related mechanisms were systematically investigated. The results showed that mnHA bioceramics could promote cell adhesion, proliferation, alkaline phosphatase (ALP) activity, and expression of osteogenic/cementogenic-related markers including runt-related transcription factor 2 (Runx2), ALP, osteocalcin (OCN), cementum attachment protein (CAP), and cementum protein (CEMP) as compared to the HA bioceramics with flat and dense surface. Moreover, mnHA bioceramics stimulated gene expression of low-density lipoprotein receptor-related protein 5 (LRP5) and β-catenin, which are the key genes of canonical Wnt signaling. Moreover, the stimulatory effect on ALP activity and osteogenic and cementogenic gene expression, including that of ALP, OCN, CAP, CEMP, and Runx2 of mnHA bioceramics could be repressed by canonical Wnt signaling inhibitor dickkopf1 (Dkk1). The results suggested that the HA bioceramics with mnHA could act as promising grafts for periodontal tissue regeneration.

  2. Bioactivity evaluation of commercial calcium phosphate-based bioceramics for bone regeneration

    Energy Technology Data Exchange (ETDEWEB)

    Borrós, S.; Mas, A.

    2016-11-01

    Calcium phosphate-based bioceramics constitute a great promise for bone tissue engineering as they chemically resemble to mammalian bone and teeth. Their use is a viable alternative for bone regeneration as it avoids the use of autografts and allografts, which usually involves immunogenic reactions and patient’s discomfort. This work evolves around the study of the bioactivity potential of different commercially available bone substitutes based in calcium phosphate through the characterization of their ionic exchangeability when immersed in simulated body fluid (SBF). (Author)

  3. Analysis of radiopacity, pH and cytotoxicity of a new bioceramic material

    OpenAIRE

    2015-01-01

    AbstractObjective RetroMTA® is a new hydraulic bioceramic indicated for pulp capping, perforations or root resorption repair, apexification and apical surgery. The aim of this study was to compare the radiopacity, pH variation and cytotoxicity of this material to ProRoot® MTA.Material and Methods Mixed cements were exposed to a digital x-ray along with an aluminum stepwedge for the radiopacity assay. pH values were verified after incubation period of 3, 24, 48, 72 and 168 hours. The cytotoxic...

  4. Fascinating properties of bioactive templated glasses: A new generation of nanostructured bioceramics

    Science.gov (United States)

    Izquierdo-Barba, Isabel; Vallet-Regí, María

    2011-04-01

    This review article, dedicated to Prof. Osamu Terasaki, is focused on current trends in nanostructured bioceramics in the field of bone repair and regeneration. This communication overviews the main characteristics of so called "templated glasses" recently described which exhibit an outstanding bioactive behavior compared with conventional bioactive glasses. A deep study regarding the control of textural, structural and compositional properties in the nanometric scale in relation to the charming bioactivity properties described for these nanostructured materials is herein discussed. The possibility to tailor such properties offers a wide range of reactivity/bioactivity depending on the medical application requested.

  5. The Effect of Photoluminescence of Bioceramic Irradiation on Middle Cerebral Arterial Occlusion in Rats

    Directory of Open Access Journals (Sweden)

    Lei Zhang

    2016-01-01

    Full Text Available The purpose of this study is to determine the possible effect of photoluminescence of bioceramic (PLB on ischemic cerebral infarction (stroke, by using an animal model of transient middle cerebral artery occlusion (MCAO. Sprague-Dawley rats were used to induce MCAO to block the origin of the left MCAO; three months later, the positive chronic stroke rats were selected by running tunnel maze; the MCAO rats with significant chronic stroke and neurological defects were used for treadmill experiments with varying speed settings to test their capability for restoration after muscular fatigue under conditions of with and without PLB irradiation. As a result, PLB irradiation could improve exercise completion rate and average running speed during slow and fast treadmill settings. After PLB irradiation, the selected MCAO rats successfully completed all the second-round treadmill exercises at the maximum speed setting, and they had better restoration from muscular fatigue. An in vitro cell study on astrocytes of rats by bioceramic irradiation further demonstrated increased intracellular nitric oxide. To explain these results, we suggest that cortical brain stimulation of microcirculation and enhancement of peripheral muscular activity are the main causes of the improved exercise performance in MCAO rats by PLB.

  6. Preparation and analysis of chemically gradient functional bioceramic coating formed by pulsed laser deposition.

    Science.gov (United States)

    Rajesh, P; Muraleedharan, C V; Sureshbabu, S; Komath, Manoj; Varma, Harikrishna

    2012-02-01

    Bioactive ceramic coatings based on calcium phosphates yield better functionality in the human body for a variety of metallic implant devices including orthopaedic and dental prostheses. In the present study chemically and hence functionally gradient bioceramic coating was obtained by pulsed laser deposition method. Calcium phosphate bioactive ceramic coatings based on hydroxyapatite (HA) and tricalcium phosphate (TCP) were deposited over titanium substrate to produce gradation in physico-chemical characteristics and in vitro dissolution behaviour. Sintered targets of HA and α-TCP were deposited in a multi target laser deposition system. The obtained deposits were characterized by X-ray diffraction, fourier transform infrared spectroscopy, scanning electron microscopy and energy dispersive X-ray analysis. Inductively coupled plasma spectroscopy was used to estimate the in vitro dissolution behaviour of coatings. The variation in mechanical property of the gradient layer was evaluated through scratch test and micro-indentation hardness. The bioactivity was examined in vitro with respect to the ability of HA layer to form on the surface as a result of contact with simulated body fluid. It could be inferred that chemically gradient functional bioceramic coating can be produced by laser deposition of multiple sintered targets with variable chemical composition.

  7. Improvement of organics removal by bio-ceramic filtration of raw water with addition of phosphorus.

    Science.gov (United States)

    Sang, Junqiang; Zhang, Xihui; Li, Lingzhi; Wang, Zhansheng

    2003-11-01

    The purpose of this study was to investigate the effect of phosphorus addition on biological pretreatment of raw water. Experiments were conducted in pilot-scale bio-ceramic filters with raw water from a reservoir located in Beijing, China. The results demonstrated that phosphorus was the limiting nutrient for bacterial growth in the raw water investigated in this study. The measured values of bacterial regrowth potential (BRP) and biodegradable dissolved organic carbon (BDOC) of the raw water increased by 50-65% and 30-40% with addition of 50 microg of PO4(3-)-PL(-1), respectively. Addition of 25 microg of PO4(3-)-PL(-1) to the influent of bio-ceramic filter enhanced the percent removal of organics by 4.6, 5.7 and 15 percentage points in terms of COD(Mn), TOC and BDOC, respectively. Biomass in terms of phospholipid content increased by 13-22% and oxygen uptake rate (OUR) increased by 35-45%. The ratio of C:P for bacteria growth was 100:1.6 for the raw water used in this study. Since change of phosphorus concentrations can influence the performance of biological pretreatment and the biological stability of drinking water, this study is of substantial significance for waterworks in China. The role of phosphorus in biological processes of drinking water should deserve more attention.

  8. Sterilization can change properties of bioceramics; Ein Sterilisationsprozess kann die Eigenschaften von Biokeramik veraendern

    Energy Technology Data Exchange (ETDEWEB)

    Willmann, G. [CeramTec AG, Postfach 1149, D-73201 Plochingen (Germany)

    2003-02-01

    Bioceramics made of bioinert alumina or zirconia and bioactive hydroxyapatite are well established implant materials. Implants have to be cleaned and sterilized. When sterilized some bioceramics change their color. This may effect their properties. No decrease of mechanical strength is observed when sterilizing alumina and the novel ceramic biocomposite AMC (Alumina Matrix Composite) with steam or Co{sup 60} Gamma irradiation. When sterilizing Y-TZP zirconia with steam a decrease of strength is observed. (Abstract Copyright [2003], Wiley Periodicals, Inc.) [German] Biokeramik auf Basis von bioinertem Aluminium- und Zirkonoxid, so wie bioaktivem Hydroxylapatit sind etablierte Werkstoffe fuer Implantate. Implantate muessen gereinigt und sterilisiert werden. Bei einigen Biokeramiken koennen beim Sterilisieren Veraenderungen ihrer Farbe auftreten, die aber keinen unguenstigen Einfluss auf die Gebrauchseigenschaften haben. Das Sterilisieren mit Dampf im Autoklaven und mit Co{sup 60} Gamma Strahlung verursacht keinen Festigkeitsabfall bei Aluminiumoxidkeramik und bei dem neuen, keramischen Biokomposit AMC (Alumina Matrix Composite). Bei Y-TZP Zirkonoxidkeramik dagegen wurde beim Sterilisieren mit Dampf ein Festigkeitsabfall gefunden. (Abstract Copyright [2003], Wiley Periodicals, Inc.)

  9. Toward smart implant synthesis: bonding bioceramics of different resorbability to match bone growth rates.

    Science.gov (United States)

    Comesaña, Rafael; Lusquiños, Fernando; Del Val, Jesús; Quintero, Félix; Riveiro, Antonio; Boutinguiza, Mohamed; Jones, Julian R; Hill, Robert G; Pou, Juan

    2015-06-02

    Craniofacial reconstructive surgery requires a bioactive bone implant capable to provide a gradual resorbability and to adjust to the kinetics of new bone formation during healing. Biomaterials made of calcium phosphate or bioactive glasses are currently available, mainly as bone defect fillers, but it is still required a versatile processing technique to fabricate composition-gradient bioceramics for application as controlled resorption implants. Here it is reported the application of rapid prototyping based on laser cladding to produce three-dimensional bioceramic implants comprising of a calcium phosphate inner core, with moderate in vitro degradation at physiological pH, surrounded by a bioactive glass outer layer of higher degradability. Each component of the implant is validated in terms of chemical and physical properties, and absence of toxicity. Pre-osteoblastic cell adhesion and proliferation assays reveal the adherence and growth of new bone cells on the material. This technique affords implants with gradual-resorbability for restoration of low-load-bearing bone.

  10. 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.

  11. Physicochemical Properties of Epoxy Resin-Based and Bioceramic-Based Root Canal Sealers

    Science.gov (United States)

    Lee, Ju Kyung; Kwak, Sang Won; Ha, Jung-Hong; Lee, WooCheol

    2017-01-01

    Three bioceramic sealers (EndoSequence BC sealer, EndoSeal MTA, and MTA Fillapex) and three epoxy resin-based sealers (AH-Plus, AD Seal, and Radic-Sealer) were tested to evaluate the physicochemical properties: flow, final setting time, radiopacity, dimensional stability, and pH change. The one-way ANOVA and Tukey's post hoc test were used to analyze the data (P = 0.05). The MTA Fillapex sealer had a highest flow and the BC Sealer presented a flow significantly lower than the others (P MTA Fillapex samples were not set in humid incubator condition even after one month. EndoSeal MTA had the longest setting time among the measurable materials and Radic-Sealer and AD Seal showed shorter setting time than the AH-Plus (P MTA showed statistically higher values and MTA Fillapex showed statistically lower radiopacity (P MTA presented a significant increase of pH over experimental time for 4 weeks. In conclusion, the bioceramic sealer and epoxy resin-based sealers showed clinical acceptable physicochemical properties, but BC Sealer and MTA Fillapex were not set completely. PMID:28210204

  12. Biocerâmicas: tendências e perspectivas de uma área interdisciplinar Bioceramics: tendencies and perspectives of an interdisciplinary area

    Directory of Open Access Journals (Sweden)

    Elizabete Y. Kawachi

    2000-08-01

    Full Text Available The need for new materials to substitute injured or damaged parts of the human body has led scientists of different areas to the investigation of bioceramics since the 70's, when other materials in use started to show implantation problems. Bioceramics show some advantages like being the material that best mimics the bone tissue but also, present low mechanical strength due to its ceramic nature. This paper presents a general view about the topic.

  13. Quantification of bone mass gain in response to the application of biphasic bioceramics and platelet concentrate in critical-size bone defects.

    Science.gov (United States)

    Lobo, Sonja Ellen; Wykrota, Francisco Henrique Lanna; Oliveira, Ana Carolina Marques Barbosa; Kerkis, Irina; Mahecha, Germán Bohorquez; Alves, Humberto José

    2009-05-01

    Biphasic bioceramics have been widely indicated for bone reconstruction; however, the real gain in bone mass due to the presence of such biomaterials has not been established yet nor the advantages of its association with platelet concentrate. This study aims at quantifying the volume of bone matrix, osteoblasts, osteocytes, blood vessels and adipose tissue after the application of a biphasic bioceramics composed of 65% hydroxyapatite and 35% beta-tricalcium phosphate. Critical-size bone defects were produced in rabbit femora and reconstructed with bioceramics only, with bioceramics combined with platelet concentrate, with platelet concentrate alone, and with no treatment (blood clot). The quantitative evaluation was performed on histological sections using histomorphometry. Our data provide original evidence that consolidates the indication of bioceramics for clinical bone loss reconstruction. The application of biphasic bioceramics alone led to major bone mass gain and was followed by its association with platelet concentrate. On the other hand, platelet concentrate can contribute to the augmentation and maintenance of the adipose tissue, representing a new field for future applications in plastic surgery.

  14. Micro-configuration Observation of Porous Bioceramic for Sliding on Intestinal Mucus Film

    Institute of Scientific and Technical Information of China (English)

    2005-01-01

    The microstructure of the prepared porous bioceramic material, including surface porosity and apparent contact area with the artificial mucus film are computed and analyzed. The surface micro-configurations of the porous material before and after sliding on the mucus ftlm are observed in 2D and 3 D by digital microscopy. We describe how much mucus enters and stays within different pores, and how the porous material with rough/porous surface contacts with the mucus film ( elastic surface/gel). The presented results illustrate that the material with different porous structure can lead to different mucus suction, surface scraping and changes of contact area and condition during sliding, which will be active for high friction of robotic endoscope with the intestinal wall for intestinal locomotion.

  15. The affect of densification and dehydroxylation on the mechanical properties of stoichiometric hydroxyapatite bioceramics

    Energy Technology Data Exchange (ETDEWEB)

    Laasri, S.; Taha, M. [Laboratoire de Thermodynamique Metallurgie et Rheologie des Materiaux, Universite Ibn Zohr, Faculte des sciences, BP8106 Cite Dakhla, Agadir (Morocco); Laghzizil, A., E-mail: laghzizi@fsr.ac.ma [Laboratoire de Chimie Physique Generale, Universite Mohammed V Rabat BP1014 (Morocco); Hlil, E.K. [Institut Neel MCMF, CNRS, BP 166, 38042 Grenoble Cedex 9 (France); Chevalier, J. [Universite de Lyon, INSA-Lyon, MATEIS UMR CNRS 5510, 20 Avenue Albert Einstein, 69621 Villeurbanne Cedex (France)

    2010-10-15

    This paper reports the effects of processing densification on the mechanical properties of hydroxyapatite bioceramics. Densification of synthetic hydroxyapatite is conducted in the range 1000-1300 {sup o}C. X-ray diffraction and SEM microscopy are used to check the microstructure transformations. Vickers hardness, toughness and Young's modulus are analyzed versus the density and grain size. The sintering temperature and the particle size influence strongly the densification and the resulting mechanical properties. In addition, the critical sintering temperature appears around 1200 {sup o}C and the declined strength at the temperature up to 1200 {sup o}C is found sensitive to the dehydroxylation process of hydroxyapatite.

  16. Synthesis of bioactive β-TCP coatings with tailored physico-chemical properties on zirconia bioceramics.

    Science.gov (United States)

    Stefanic, Martin; Milacic, Radmila; Drazic, Goran; Škarabot, Miha; Budič, Bojan; Krnel, Kristoffer; Kosmač, Tomaž

    2014-10-01

    The objective of this work was to develop a synthesis procedure for the deposition of β-TCP coatings with tailored physico-chemical properties on zirconia bioceramics. The synthesis procedure involved two steps: (i) a rapid wet-chemical deposition of a biomimetic CaP coating and (ii) a subsequent post-deposition processing of the biomimetic CaP coating, which included a heat treatment between 800 and 1200 °C, followed by a short sonication in a water bath. By regulating the heating temperature the topography of the β-TCP coatings could be controlled. The average surface roughness (Ra) ranged from 42 nm for the coating that was heated at 900 °C (TCP-900) to 630 nm for the TCP-1200 coating. Moreover, the heating temperature also affected the dissolution rate of the coatings in a physiological solution, their protein-adsorption capacity and their bioactivity in a simulated body fluid.

  17. Degradation and drug release in calcium polyphosphate bioceramics: an MRI-based characterization.

    Science.gov (United States)

    Bray, J M; Filiaggi, M J; Bowen, C V; Beyea, S D

    2012-10-01

    Degradable, bioceramic bone implants made of calcium polyphosphate (CPP) hold potential for controlled release of therapeutic agents in the treatment of localized bone disease. Magnetic resonance imaging techniques for non-invasively mapping fluid distribution, T(1) and T(2) relaxation times and the apparent diffusion coefficient were performed in conjunction with a drug elution protocol to resolve free and bound water components within the material microstructure in two CPP formulations (G1 and G2). The T(2) maps provided the most accurate estimates of free and bound water, and showed that G1 disks contained a detectable free water component at all times, with drug release dominated by a Fickian diffusion mechanism. Drug release from G2 disks was characterized by a combined diffusional/structural relaxation mechanism, which may be related to the gradual infiltration of a free water component associated with swelling and/or chemical degradation.

  18. Standard Enucleation with Aluminium Oxide Implant (Bioceramic Covered with Patient's Sclera

    Directory of Open Access Journals (Sweden)

    Gian Luigi Zigiotti

    2012-01-01

    Full Text Available Purpose. We describe in our study a modified standard enucleation, using sclera harvested from the enucleated eye to cover the prosthesis in order to insert a large porous implant and to reduce postoperative complication rates in a phthisis globe. Methods. We perform initially a standard enucleation. The porous implant (Bioceramic is then covered only partially by the patient's sclera. The implant is inserted in the posterior Tenon's space with the scleral covering looking at front. All patients were followed at least for twelve months (average followup 16 months. Results. We performed nineteen primary procedures (19 patients, 19 eyes, M; F and secondary, to fill the orbital cavity in patients already operated by standard evisceration (7 patients, 7 eyes. There were no cases of implant extrusion. The orbital volume was well reintegrated. Conclusion. Our procedure was safe and effective. All patients had a good cosmetic result after final prosthetic fitting and we also achieved good prothesis mobility.

  19. Mechanochemical synthesis evaluation of nanocrystalline bone-derived bioceramic powder using for bone tissue engineering

    Directory of Open Access Journals (Sweden)

    Amirsalar Khandan

    2014-01-01

    Full Text Available Introduction: Bone tissue engineering proposes a suitable way to regenerate lost bones. Different materials have been considered for use in bone tissue engineering. Hydroxyapatite (HA is a significant success of bioceramics as a bone tissue repairing biomaterial. Among different bioceramic materials, recent interest has been risen on fluorinated hydroxyapatites, (FHA, Ca 10 (PO 4 6 F x (OH 2−x . Fluorine ions can promote apatite formation and improve the stability of HA in the biological environments. Therefore, they have been developed for bone tissue engineering. The aim of this study was to synthesize and characterize the FHA nanopowder via mechanochemical (MC methods. Materials and Methods: Natural hydroxyapatite (NHA 95.7 wt.% and calcium fluoride (CaF 2 powder 4.3 wt.% were used for synthesis of FHA. MC reaction was performed in the planetary milling balls using a porcelain cup and alumina balls. Ratio of balls to reactant materials was 15:1 at 400 rpm rotation speed. The structures of the powdered particles formed at different milling times were evaluated by X-ray diffraction (XRD, scanning electron microscopy (SEM and transmission electron microscopy (TEM. Results: Fabrication of FHA from natural sources like bovine bone achieved after 8 h ball milling with pure nanopowder. Conclusion: F− ion enhances the crystallization and mechanical properties of HA in formation of bone. The produced FHA was in nano-scale, and its crystal size was about 80-90 nm with sphere distribution in shape and size. FHA powder is a suitable biomaterial for bone tissue engineering.

  20. Niobium-Doped Hydroxyapatite Bioceramics: Synthesis, Characterization and In Vitro Cytocompatibility

    Directory of Open Access Journals (Sweden)

    Nádia S. V. Capanema

    2015-07-01

    Full Text Available Doping calcium phosphates with ionic species can play an important role in biological responses promoting alkaline phosphatase activity, and, therefore inducing the generation of new bone. Thus, in this study, the synthesis of niobium-doped hydroxyapatite (Nb-HA nanosize particles obtained by the precipitation process in aqueous media followed by thermal treatment is presented. The bioceramics were extensively characterized by X-ray diffraction, wavelength dispersive X-ray fluorescence spectrometry, Fourier transform infrared spectroscopy, scanning electron microscopy/energy dispersive X-ray spectroscopy analysis, transmission electron microscopy, atomic force microscopy and thermal analysis regarding their chemical composition, structure and morphology. The results showed that the precipitate dried at 110 °C was composed of amorphous calcium phosphate and HA, with polidisperse particles ranging from micro to nano dimensions. After the thermal treatment at 900 °C, the bioceramic system evolved predominantly to HA crystalline phase, with evident features of particle sintering and reduction of surface area. Moreover, the addition of 10 mol% of niobium salt precursor during the synthesis indicated the complete incorporation of the Nb(V species in the HA crystals with detectable changes in the original lattice parameters. Furthermore, the incorporation of Nb ions caused a significant refinement on the average particle size of HA. Finally, the preliminary cytocompatibility response of the biomaterials was accessed by human osteoblast cell culture using MTT and resazurin assays, which demonstrated no cytotoxicity of the Nb-alloyed hydroxyapatite. Thus, these findings seem promising for developing innovative Nb-doped calcium phosphates as artificial biomaterials for potential use in bone replacements and repair.

  1. Atomic scale modeling of iron-doped biphasic calcium phosphate bioceramics.

    Science.gov (United States)

    Gomes, Sandrine; Kaur, Amandeep; Grenèche, Jean-Marc; Nedelec, Jean-Marie; Renaudin, Guillaume

    2017-03-01

    Biphasic calcium phosphates (BCPs) are bioceramics composed of hydroxyapatite (HAp, Ca10(PO4)6(OH)2) and beta-Tricalcium Phosphate (β-TCP, Ca3(PO4)2). Because their chemical and mineral composition closely resembles that of the mineral component of bone, they are potentially interesting candidates for bone repair surgery, and doping can advantageously be used to improve their biological behavior. However, it is important to describe the doping mechanism of BCP thoroughly in order to be able to master its synthesis and then to fully appraise the benefit of the doping process. In the present paper we describe the ferric doping mechanism: the crystallographic description of our samples, sintered at between 500°C and 1100°C, was provided by Rietveld analyses on X-ray powder diffraction, and the results were confirmed using X-ray absorption spectroscopy and (57)Fe Mössbauer spectrometry. The mechanism is temperature-dependent, like the previously reported zinc doping mechanism. Doping was performed on the HAp phase, at high temperature only, by an insertion mechanism. The Fe(3+) interstitial site is located in the HAp hexagonal channel, shifted from its centre to form a triangular three-fold coordination. At lower temperatures, the Fe(3+) are located at the centre of the channel, forming linear two-fold coordinated O-Fe-O entities. The knowledge of the doping mechanism is a prerequisite for a correct synthesis of the targeted bioceramic with the adapted (Ca+Fe)/P ratio, and so to be able to correctly predict its potential iron release or magnetic properties.

  2. Response of stem cells from different origins to biphasic calcium phosphate bioceramics.

    Science.gov (United States)

    Lobo, Sonja E; Glickman, Robert; da Silva, Wagner N; Arinzeh, Treena L; Kerkis, Irina

    2015-08-01

    Biphasic calcium phosphate (BCP) bioceramics have been successfully applied in a broad variety of presentation forms and with different ratios of hydroxyapatite (HA) and β-tricalcium phosphate (β-TCP). BCPs have been loaded with stem cells from different origins for bone tissue engineering purposes, but evidence of stem cell behavior on different compositions (various HA/β-TCP ratios) and physical features of BCPs is limited. We compared the adhesion, proliferation, viability and osteogenic potential of human mesenchymal stem cells (MSCs) on granular BCPs with equal HA/β-TCP ratio of diverse particle sizes and on porous blocks which had different chemical compositions. In addition, the osteogenic differentiation of MSCs was compared to adipose-derived (ADSC) and dental pulp (DPSC) stem cells, as well as to pre-osteoblasts on a particulate BCP. MSCs growing on granular BCPs demonstrated increased number as compared to MSCs growing on blocks. Cells proliferated to a greater extent on small granular BCPs, while large granular BCPs and blocks promoted cell differentiation. Surprisingly, the expression of genes involved in osteogenesis was upregulated in MSCs on bioceramics in basal medium which indicates that BCPs may have osteoinductive potential. This was confirmed with the upregulation of osteochondrogenic markers, at different time points, when stem cells from various tissues were grown on the BCP. This study demonstrates that BCPs, depending on their physical features and chemical composition, modulate stem cell behavior, and that stem cells from different origins are inherently distinct in their gene expression profile and can be triggered toward osteochondrogenic fate by BCPs.

  3. Sputter deposited bioceramic coatings: surface characterisation and initial protein adsorption studies using surface-MALDI-MS.

    Science.gov (United States)

    Boyd, A R; Burke, G A; Duffy, H; Holmberg, M; O' Kane, C; Meenan, B J; Kingshott, P

    2011-01-01

    Protein adsorption onto calcium phosphate (Ca-P) bioceramics utilised in hard tissue implant applications has been highlighted as one of the key events that influences the subsequent biological response, in vivo. This work reports on the use of surface-matrix assisted laser desorption ionisation mass spectrometry (Surface-MALDI-MS) as a technique for the direct detection of foetal bovine serum (FBS) proteins adsorbed to hybrid calcium phosphate/titanium dioxide surfaces produced by a novel radio frequency (RF) magnetron sputtering method incorporating in situ annealing between 500°C and 700°C during deposition. XRD and XPS analysis indicated that the coatings produced at 700°C were hybrid in nature, with the presence of Ca-P and titanium dioxide clearly observed in the outer surface layer. In addition to this, the Ca/P ratio was seen to increase with increasing annealing temperature, with values of between 2.0 and 2.26 obtained for the 700°C samples. After exposure to FBS solution, surface-MALDI-MS indicated that there were significant differences in the protein patterns as shown by unique peaks detected at masses below 23.1 kDa for the different surfaces. These adsorbates were assigned to a combination of growth factors and lipoproteins present in serum. From the data obtained here it is evident that surface-MALDI-MS has significant utility as a tool for studying the dynamic nature of protein adsorption onto the surfaces of bioceramic coatings, which most likely plays a significant role in subsequent bioactivity of the materials.

  4. TOPICAL REVIEW: Trend report on international and Japanese standardization activities for bioceramics and tissue engineered medical products

    Science.gov (United States)

    Tsutsumi, Sadami

    2010-02-01

    Since porous and injectable bioceramics have recently been utilized often as scaffolds for bone regenerative medicine, the need for their standardization has increased. One of the standard proposals in ISO/TC150 and JIS has been a draft for characterization of the porous bioceramic scaffolds in both micro- and macro-scopic aspects. ISO/TC150/SC7 (Tissue engineered medical products) has been co-chaired by Professor J E Lemons, Department of Surgery, University of Alabama at Birmingham and Dr R Nakaoka, Division of Medical Devices, National Institute of Health Sciences, Japan. The scope of SC7 has been specified as 'Standardization for the general requirements and performance of tissue engineered medical products with the exclusion of gene therapy, transplantation and transfusion'.

  5. Current perspectives of bio-ceramic technology in endodontics: calcium enriched mixture cement - review of its composition, properties and applications.

    Science.gov (United States)

    Utneja, Shivani; Nawal, Ruchika Roongta; Talwar, Sangeeta; Verma, Mahesh

    2015-02-01

    Advancements in bio-ceramic technology has revolutionised endodontic material science by enhancing the treatment outcome for patients. This class of dental materials conciliates excellent biocompatibility with high osseoconductivity that render them ideal for endodontic care. Few recently introduced bio-ceramic materials have shown considerable clinical success over their early generations in terms of good handling characteristics. Calcium enriched mixture (CEM) cement, Endosequence sealer, and root repair materials, Biodentine and BioAggregate are the new classes of bio-ceramic materials. The aim of this literature review is to present investigations regarding properties and applications of CEM cement in endodontics. A review of the existing literature was performed by using electronic and hand searching methods for CEM cement from January 2006 to December 2013. CEM cement has a different chemical composition from that of mineral trioxide aggregate (MTA) but has similar clinical applications. It combines the biocompatibility of MTA with more efficient characteristics, such as significantly shorter setting time, good handling characteristics, no staining of tooth and effective seal against bacterial leakage.

  6. The effect of grain size on the biocompatibility, cell-materials interface, and mechanical properties of microwave-sintered bioceramics.

    Science.gov (United States)

    Veljović, Djordje; Colić, Miodrag; Kojić, Vesna; Bogdanović, Gordana; Kojić, Zvezdana; Banjac, Andrijana; Palcevskis, Eriks; Petrović, Rada; Janaćković, Djordje

    2012-11-01

    The effect of decreasing the grain size on the biocompatibility, cell-material interface, and mechanical properties of microwave-sintered monophase hydroxyapatite bioceramics was investigated in this study. A nanosized stoichiometric hydroxyapatite powder was isostatically pressed at high pressure and sintered in a microwave furnace in order to obtain fine grained dense bioceramics. The samples sintered at 1200°C, with a density near the theoretical one, were composed of micron-sized grains, while the grain size decreased to 130 nm on decreasing the sintering temperature to 900°C. This decrease in the grain size certainly led to increases in the fracture toughness by much as 54%. An in vitro investigation of biocompatibility with L929 and human MRC-5 fibroblast cells showed noncytotoxic effects for both types of bioceramics, while the relative cell proliferation rate, cell attachment and metabolic activity of the fibroblasts were improved with decreasing of grain size. An initial in vivo investigation of biocompatibility by the primary cutaneous irritation test showed that both materials exhibited no irritation properties.

  7. Osteogenic differentiation of osteoblasts induced by calcium silicate and calcium silicate/β-tricalcium phosphate composite bioceramics.

    Science.gov (United States)

    Fei, Lisha; Wang, Chen; Xue, Yang; Lin, Kaili; Chang, Jiang; Sun, Jiao

    2012-07-01

    In this study, calcium silicate (CS) and CS/β-tricalcium phosphate (CS/β-TCP) composites were investigated on their mechanism of osteogenic proliferation and differentiation through regulating osteogenic-related gene and proteins. Osteoblast-like cells were cultured in the extracts of these CS-based bioceramics and pure β-TCP, respectively. The main ionic content in extracts was analyzed by inductively coupled plasma-atomic emission spectroscopy. The cell viability, mineralization, and differentiation were evaluated by MTT assay, Alizarin Red-S staining and alkaline phosphatase (ALP) activity assay. The expressions of BMP-2, transforming growth factor-β (TGF-β), Runx2, ALP, and osteocalcin (OCN) at both gene and protein level were detected by real-time polymerase chain reaction analysis and Western blot. The result showed that the extracts of CS-based bioceramics promoted cells proliferation, differentiation, and mineralization when compared with pure β-TCP. Accordingly, pure CS and CS/β-TCP composites stimulated osteoblast-like cells to express BMP-2/TGF-β gene and proteins, and further regulate the expression of Runx2 gene and protein, and ultimately affect the ALP activity and OCN deposition. This study suggested that the CS-based bioceramics could not only promote the expression of osteogenic-related genes but also enhance the genes to encode the corresponding proteins, which could finally control osteoblast-like cells proliferation and differentiation.

  8. The effect of powder properties on sintering, microstructure, mechanical strength and degradability of beta-tricalcium phosphate/calcium silicate composite bioceramics

    Energy Technology Data Exchange (ETDEWEB)

    Lin Kaili; Chang Jiang; Shen Ruxiang, E-mail: jchang@mail.sic.ac.c [State Key Laboratory of High Performance Ceramics and Superfine Microstructure, Shanghai Institute of Ceramics, Chinese Academy of Sciences, 1295 Dingxi Road, Shanghai 200050 (China)

    2009-12-15

    The effect of powder properties on sintering, microstructure, mechanical strength and degradability of beta-tricalcium phosphate/Calcium silicate (beta-Ca{sub 3}(PO{sub 4}){sub 2}/CaSiO{sub 3}, beta-TCP/CS) composite bioceramics was investigated. beta-TCP/CS composite powders with a weight ratio of 50:50 were prepared by three different methods: mechanical milling method (TW-A), two-step chemical precipitation method (TW-B) and in situ chemical co-precipitation method (TW-C), and then the three composite powders were uniaxially compacted at 30 MPa, followed by cold isostatic pressing into rectangular-prism-shaped specimens under a pressure of 200 MPa for 15 min, and then sintered at 1150 deg. C for 5 h. The TW-B powders with less agglomerative morphologies and uniform nano-size particles attained 96.14% relative density (RD). A uniform microstructure with about 120 nm grains was observed. Whereas, the samples obtained from TW-A and TW-C powders only reached a RD of 63.08% and 78.86%, respectively. The bending strength of the samples fabricated from TW-B reached 125 MPa, which was more than 3.7 and 1.5 times higher as compared with that of samples obtained from TW-A and TW-C powders, respectively. Furthermore, the degradability of the samples fabricated from TW-B powders was obviously lower than that of the samples fabricated from TW-A and TW-C powders.

  9. Effect of Y2O3 Content on Microstructure of Gradient Bioceramic Composite Coating Produced by Wide-Band Laser Cladding

    Institute of Scientific and Technical Information of China (English)

    Liu Qibin; Zou Jianglong; Zheng Min; Dong Chuang

    2005-01-01

    To eliminate thermal stress and cracks in the process of laser cladding, a kind of bioceramic coating with gradient compositional design was prepared on the surface of Ti alloy by using wide-band laser cladding. And effect of Y2O3 content on gradient bioceramic composite coating was studied. The experimental results indicate that adding rare earth can refine grain. Different rare earth contents affect formation of HA and β-TCP in bioceramic coating. When the content of rare earth ranges from 0.4% to 0.6%, the active extent of rare earth in synthesizing HA and β-TCP is the best, which indicates that "monosodium glutamate" effect of rare earth plays a dominant role. However, when rare earth content is up to 0.8%, the amount of synthesizing HA and β-TCP in coating conversely goes down, which demonstrates that rare earth gradually losts its catalysis in manufacturing HA and β-TCP.

  10. Effect of sputter deposited YSZ thin films on the fracture behavior of dental bioceramics

    Science.gov (United States)

    Teixeira, Erica Cappelletto Nogueira

    The fracture behavior of dental bioceramic materials was evaluated under physiologic conditions when modified by yttria stabilized zirconia (YSZ) thin film deposition. It was hypothesized that changing the YSZ thin film properties will produce a significant enhancement in the strength of bioceramic materials, ultimately promoting a more fatigue resistant construct. Porcelain, alumina, and zirconia were evaluated in terms of dynamic fatigue for an initial characterization of their fracture behavior. Data showed that strength degradation occurred in all three materials, most drastically in porcelain. Initial strength measurements, focused on depositing YSZ thin films on three unique substrates; porcelain, alumina, and zirconia, were carried out. A significant increase in strength was observed for alumina and porcelain. Since strength alone is not enough to characterize the fracture behavior of brittle materials, coated specimens of porcelain and zirconia were subjected to dynamic fatigue and Weibull analysis. Coated YSZ porcelain specimens showed a significant increase in strength at all tested stressing rates. YSZ coated zirconia specimens showed similar strength values at all stressing rates. The effect of film thickness on porcelain was also evaluated. Data demonstrated that film thickness alone does not appear to control increases in the flexural strength of a modified substrate. It is expected that deposition induced stress in YSZ sputtered films does not change with film thickness. However, a thicker film will generate a larger force at the film/substrate interface, contributing to delamination of the film. It was clear that in order to have a significant improvement in the fracture behavior of porcelain, changing the thickness of the film is not enough. The columnar structure of the YSZ films developed seems to favor an easy path for crack propagation limiting the benefits expected by the coating. The effect of a multilayered film, composed by brittle

  11. Preparation of porous bioceramics using reverse thermo-responsive hydrogels in combination with rhBMP-2 carriers: in vitro and in vivo evaluation.

    Science.gov (United States)

    Fu, Yin-Chih; Chen, Chung-Hwan; Wang, Chau-Zen; Wang, Yan-Hsiung; Chang, Je-Ken; Wang, Gwo-Jaw; Ho, Mei-Ling; Wang, Chih-Kuang

    2013-11-01

    Porous biphasic calcium phosphates (BCP) were fabricated using reverse thermo-responsive hydrogels with hydroxyapatite (HAp) and β-tricalcium (β-TCP) powder and planetary centrifugal mixer. This hydrogel mixture slurry will shrink and compress the HAp powder during the sintering process. The porous bioceramics are expected to have good mechanical properties after sintering at 1200°C. Reverse thermo-responsive hydrogels of poly[(N-isopropylacrylamide)-co-(methacrylic acid)] p(NiPAAm-MAA) were synthesized by free-radical cross-linking copolymerization, and their chemical properties were evaluated by nuclear magnetic resonance spectroscopy, infrared spectroscopy, and electrospray-ionization mass spectrometry. The lower critical solution temperature (LCST) of the hydrogel was determined using turbidity measurements. A thermogravimetric analysis was used to examine the thermal properties. The porous bioceramic properties were analyzed by X-ray diffraction, scanning electron microscopy, bulk density, compressive strength testing and cytotoxicity. The compressive strength and average porosity of the porous bioceramics were examined at approximately 6.8MPa and 66% under 10wt% p(NiPAAm-MAA)=99:1 condition. The ratio of HAp/β-TCP can adjust two different compositional behaviors during the 1200°C sintering process without resulting in cell toxicity. The (rhBMP-2)-HAp-PLGA carriers were fabricated as in our previous study of the double emulsion and drop-coating technique. Results of animal study included histological micrographs of the 1-mm defect in the femurs, with the rhBMP-2 carrier group, the bioceramic spacer group and the bioceramic spacer with rhBMP-2 carriers group showing better callus formation around the femur defect site than the control group. The optimal dual effects of the bone growth factors from osteoconductive bioceramics and osteoinductive rhBMP-2 carriers produced better bone formation.

  12. Effect of micro-nano-hybrid structured hydroxyapatite bioceramics on osteogenic and cementogenic differentiation of human periodontal ligament stem cell via Wnt signaling pathway

    Directory of Open Access Journals (Sweden)

    Mao LX

    2015-11-01

    Full Text Available Lixia Mao,1,* Jiaqiang Liu,1,* Jinglei Zhao,1 Jiang Chang,2 Lunguo Xia,1 Lingyong Jiang,1 Xiuhui Wang,2 Kaili Lin,2,3 Bing Fang11Center of Craniofacial Orthodontics, Department of Oral and Cranio-maxillofacial Science, Top Priority Clinical Medical Center of Shanghai Municipal Commission of Health and Family Planning, Ninth People’s Hospital Affiliated to Shanghai Jiao Tong University, School of Medicine, Shanghai Jiao Tong University, 2State Key Laboratory of High Performance Ceramics and Superfine Microstructure, Shanghai Institute of Ceramics, Chinese Academy of Sciences, 3Shanghai Engineering Research Center of Tooth Restoration and Regeneration, School of Stomatology, Tongji University, Shanghai, People’s Republic of China*These authors contributed equally to this workAbstract: The surface structure of bioceramic scaffolds is crucial for its bioactivity and osteoinductive ability, and in recent years, human periodontal ligament stem cells have been certified to possess high osteogenic and cementogenic differential ability. In the present study, hydroxyapatite (HA bioceramics with micro-nano-hybrid surface (mnHA [the hybrid of nanorods and microrods] were fabricated via hydrothermal reaction of the α-tricalcium phosphate granules as precursors in aqueous solution, and the effects of mnHA on the attachment, proliferation, osteogenic and cementogenic differentiations of human periodontal ligament stem cells as well as the related mechanisms were systematically investigated. The results showed that mnHA bioceramics could promote cell adhesion, proliferation, alkaline phosphatase (ALP activity, and expression of osteogenic/cementogenic-related markers including runt-related transcription factor 2 (Runx2, ALP, osteocalcin (OCN, cementum attachment protein (CAP, and cementum protein (CEMP as compared to the HA bioceramics with flat and dense surface. Moreover, mnHA bioceramics stimulated gene expression of low-density lipoprotein receptor

  13. 生物陶瓷材料在牙髓病治疗中的应用%Application of bioceramic material in endodontic therapy

    Institute of Scientific and Technical Information of China (English)

    刘佳

    2012-01-01

    生物陶瓷材料在牙髓病学领域的广泛研发和临床应用,被誉为牙髓病学材料不断更新发展的里程碑性象征.本文就生物陶瓷材料的分类、研究进展及其在牙髓病治疗中的临床应用作一综述.%Bioceramic materials have developed rapidly and been widely applied in endodontic treatment. This article reviews the classification, characteristics and endodontic application of bioceramic materials.

  14. Nanocrystalline Powders of Alkaline-Earth Phosphates as Precursors for Bioceramics

    Directory of Open Access Journals (Sweden)

    Parhi Purnendu

    2006-01-01

    Full Text Available Bone is a nanocomposite made of calcium phosphates and collagen. Collagen has a typical fibrous structure, with diameter ranging from 100 nm to 2 µm. It is suggested that calcium hydroxyapatite, Ca10(PO46(OH2 in the size range 5-50 nm embedded in the collagen framework provides mechanical strength to bone. Among calcium phosphates, apatites are found to be the most suitable for bone regeneration due to its biocompatibility. A contemporary theme is to prepare nanocrystallites of alkaline-earth phosphates that can be employed as precursors for making novel bioceramics. In this paper, we present our attempts to prepare nano-sized particles of alkaline-earth hydroxyapatites, A10(PO46(OH2 where A= Ca, Sr and Ba through a metathetical route. Our work involved the use of same reactants treated under different reaction conditions. While hydrothermal route yielded well-crystalline nanorods, microwave resulted in agglomerated hydroxyapatites and reverse micellear route gave low crystalline apatites with less agglomeration.

  15. Low temperature direct 3D printed bioceramics and biocomposites as drug release matrices.

    Science.gov (United States)

    Gbureck, Uwe; Vorndran, Elke; Müller, Frank A; Barralet, Jake E

    2007-09-26

    The aim of this study was to investigate the adsorption and desorption kinetics of antibiotics to microporous bioceramics fabricated by a novel low temperature 3D powder direct printing process. The adsorption of vancomycin, ofloxacin and tetracycline onto hydroxyapatite, brushite and monetite showed a linear correlation with the drug concentration in the immersion solution, whereas a non-linear relationship was found between the immersion time and the amount of adsorbed drug. Differences in the total amount of adsorbed drugs were correlated to the specific surface areas of the matrices, which varied between 2.4-13.1 m(2)/g. Normalised drug loadings were found to be in the range of 1.5-1.8 mg/m(2) for vancomycin and ofloxacin, whereas higher loads of up to 5-7 mg/m(2) were obtained for tetracycline. Vancomycin and ofloxacin were rapidly released into PBS buffer within 1-2 days, while tetracycline showed a much slower release rate of approximately 25% after 5 days of immersion. Additional polymer impregnation of the drug loaded matrix with PLA/PGA polymer solutions enabled the release kinetics to be delayed such that sustained release was achieved in polymer ceramic biocomposites.

  16. Simultaneous mechanical property and biodegradation improvement of wollastonite bioceramic through magnesium dilute doping.

    Science.gov (United States)

    Xie, Jiajun; Yang, Xianyan; Shao, Huifeng; Ye, Juan; He, Yong; Fu, Jianzhong; Gao, Changyou; Gou, Zhongru

    2016-02-01

    The large-area bone defects in head (including calvarial, orbital, and maxillofacial bone) and segmental bone are attracting increased attention in a wide range of clinical departments. A key requirement for the clinical success of the bioactive ceramics is the match of the mechanical behavior of the implants with the specific bone tissue to be filled. This raises the question as to what design strategy might be the best indicators for the balance between mechanical properties and biological performances. Here we go beyond the traditional approaches that use phase conversion or biphasic hybrid; instead, we achieved a simultaneous enhancement of several mechanical parameters and optimalization of biodegradability by using a dilute doping of Mg in a single-phase wollastonite bioceramic. We show that the wollastonite ceramic can be rationally tuned in phase (α or β), mechanical strength (in compression and bending mode), elastic modulus (18-23GPa), and fracture toughness (>3.2MPam(1/2)) through the usage of Mg dopant introduced at precisely defined dilute concentrations (Mg/Ca molar ratio: 1.2-2.1%). Meanwhile, the dilute Mg-doped wollastonite ceramics are shown to exhibit good bioactivity in vitro in SBF but biodegradation in Tris is inversely proportional to Mg content. Consequently, such new highly bioactive ceramics with appreciable strength and toughness are promising for making specific porous scaffolds for enhancing large segmental bone defect and thin-wall bone defect repair.

  17. Processing and characterization of multi-cellular monolithic bioceramics for bone regenerative scaffolds

    Science.gov (United States)

    Ari-Wahjoedi, Bambang; Ginta, Turnad Lenggo; Parman, Setyamartana; Abustaman, Mohd Zikri Ahmad

    2014-10-01

    Multicellular monolithic ceramic body is a ceramic material which has many gas or liquid passages partitioned by thin walls throughout the bulk material. There are many currently known advanced industrial applications of multicellular ceramics structures i.e. as supports for various catalysts, electrode support structure for solid oxide fuel cells, refractories, electric/electronic materials, aerospace vehicle re-entry heat shields and biomaterials for dental as well as orthopaedic implants by naming only a few. Multicellular ceramic bodies are usually made of ceramic phases such as mullite, cordierite, aluminum titanate or pure oxides such as silica, zirconia and alumina. What make alumina ceramics is excellent for the above functions are the intrinsic properties of alumina which are hard, wear resistant, excellent dielectric properties, resists strong acid and alkali attacks at elevated temperatures, good thermal conductivities, high strength and stiffness as well as biocompatible. In this work the processing technology leading to truly multicellular monolithic alumina ceramic bodies and their characterization are reported. Ceramic slip with 66 wt.% solid loading was found to be optimum as impregnant to the polyurethane foam template. Mullitic ceramic composite of alumina-sodium alumino disilicate-Leucite-like phases with bulk and true densities of 0.852 and 1.241 g cm-3 respectively, pore linear density of ±35 cm-1, linear and bulk volume shrinkages of 7-16% and 32 vol.% were obtained. The compressive strength and elastic modulus of the bioceramics are ≈0.5-1.0 and ≈20 MPa respectively.

  18. Evaluation of the apical sealing ability of bioceramic sealer, AH plus & epiphany: An in vitro study

    Directory of Open Access Journals (Sweden)

    Suprit Sudhir Pawar

    2014-01-01

    Full Text Available Objective: This in vitro study evaluated and compared the microleakage of three sealers; Endosequence bioceramic (BC sealer, AH Plus and Epiphany. Materials and Methods: Study was done on 75 extracted human single rooted permanent teeth, which were decoronated and the root canals were instrumented. The specimens were randomly divided into three groups (n = 25 and obturated by continuous wave condensation technique. Group A: using Endosequence BC, Group B: using AH Plus sealer, Group C: using Resilon Epiphany system. Microleakage was evaluated using dye penetration method. Teeth were split longitudinally and then horizontally markings were made at 2, 4 and 6 mm from the apex. Dye penetration evaluation was done under stereomicroscope (30X magnification. Results: The dye penetration in Group B was more than in Group A and C in both vertical and horizontal directions, suggesting that newly introduced BC sealer and Epiphany sealer sealed the root canal better compared to AH Plus Sealer. Conclusion: Newer root canal sealers seal the root canal better but cannot totally eliminate leakage.

  19. In vitro bioactivity of 3D Ti-mesh with bioceramic coatings in simulated body fluid

    Directory of Open Access Journals (Sweden)

    Wei Yi

    2014-09-01

    Full Text Available 3D Ti-mesh has been coated with bioceramics under different coating conditions, such as material compositions and micro-porosity, using a dip casting method. Hydroxyapatite (HA, micro-HA particles (HAp, a bioglass (BG and their different mixtures together with polymer additives were used to control HA-coating microstructures. Layered composites with the following coating-to-substrate designs, such as BG/Ti, HA + BG/BG/Ti and HAp + BG/BG/Ti, were fabricated. The bioactivity of these coated composites and the uncoated Ti-mesh substrate was then investigated in a simulated body fluid (SBF. The Ti-mesh substrate and BG/Ti composite did not induce biomimetic apatite deposition when they were immersed in SBF for the selected BG, a pressable dental ceramic, used in this study. After seven days in SBF, an apatite layer was formed on both HA + BG/BG/Ti and HAp + BG/BG/Ti composites. The difference is the apatite layer on the HAp + BG/BG/Ti composite was rougher and contained more micro-pores, while the apatite layer on the HA + BG/BG/Ti composite was dense and smooth. The formation of biomimetic apatite, being more bioresorbable, is favored for bone regeneration.

  20. Contrasting the beam interaction characteristics of selected lasers with a partially stabilized zirconia bio-ceramic

    Science.gov (United States)

    Lawrence, J.

    2002-08-01

    Differences in the beam interaction characteristics of a CO2 laser, a Nd : YAG laser, a high power diode laser (HPDL) and an excimer laser with a partially stabilized zirconia bio-ceramic have been studied. A derivative of Beer-Lambert's law was applied and the laser beam absorption lengths of the four lasers were calculated as 33.55×10-3 cm for the CO2 laser, 18.22×10-3 cm for the Nd : YAG laser, 17.17×10-3 cm for the HPDL and 8.41×10-6 cm for the excimer laser. It was determined graphically that the fluence threshold values at which significant material removal was effected by the CO2 laser, the Nd : YAG laser, the HPDL and the excimer laser were 52 J cm-2, 97 J cm-2, 115 J cm-2 and 0.48 J cm-2, respectively. The thermal loading value for the CO2 laser, the Nd : YAG laser, the HPDL and the excimer laser were calculated as being 1.55 kJ cm-3, 5.32 kJ cm3, 6.69 kJ cm-3 and 57.04 kJ cm-3, respectively.

  1. Bioceramic dip-coating on Ti-6Al-4V and 316L SS implant materials.

    Science.gov (United States)

    Aksakal, Bunyamin; Hanyaloglu, C

    2008-05-01

    The focus of the present study is based on more economical and rapid bioceramic coating on the most common implant substrates such as Ti-6Al-4V and 316L SS used often in orthopedics. For ceramic dip coating of implant substrates, Hydroxyapatite (HA) powder, Ca10(PO4)6(OH)2, P2O5, Na2CO3 and KH2PO4 are used to provide the gel. Ceramic films on sandblasted substrates have been deposited by using a newly manufactured dip-coating apparatus. Sample characterization is evaluated by SEM and XRD analysis. A smooth and homogeneous coating films have been obtained and average of 20 MPa bonding strength has been achieved for both Ti-6Al-4V and 316L SS alloys after sintering at 750 degrees C under flowing argon. The level of importance of the process parameters on coating was determined by using analysis of variance (ANOVA). The current process appears to be cheap, easy, and flexible to shape variations and high production rates for orthopedic applications.

  2. Effect of sintering time on the microstructure and properties of inorganic polyphosphate bioceramics

    Directory of Open Access Journals (Sweden)

    Wang Q.B.

    2010-01-01

    Full Text Available Sintering is an important step in the fabrication process of ceramic bodies, which can significantly affect the microstructure and properties of materials. In this article, calcium based inorganic polyphosphate (CPP bioceramics were synthesized by gravity sintering. Effects of the sintering time (30 minutes, 1 hour, 3 hours and 5 hours on the microstructure, physicochemical degradation and mechanical property were investigated. It was found that all prepared CPP samples for various sintering times showed a β-CPP phase at the temperature of 800ºC. The sample morphology changed to more compact with extending the sintering time from 30 minutes to 5 hours. Moreover, the grain size increased with the increase of sintering time, from 1.59 μm for 30 minutes to 3.40 μm for 5 hours. The in vitro degradation test revealed that the degradation velocity had an inverse relationship with the sintering time. The CPP samples sintering for 30 minutes showed the fastest degradation, while CPP sintering for 5 hours was the slowest one. Compression test results showed that longer sintering times led to improved mechanical properties.

  3. Stem cell technology using bioceramics: hard tissue regeneration towards clinical application.

    Science.gov (United States)

    Ohnishi, Hiroe; Oda, Yasuaki; Ohgushi, Hajime

    2010-02-01

    Mesenchymal stem cells (MSCs) are adult stem cells which show differentiation capabilities toward various cell lineages. We have already used MSCs for treatments of osteoarthritis, bone necrosis and bone tumor. For this purpose, culture expanded MSCs were combined with various ceramics and then implanted. Because of rejection response to allogeneic MSC implantation, we have utilized patients' own MSCs for the treatment. Bone marrow is a good cell source of MSCs, although the MSCs also exist in adipose tissue. When comparing osteogenic differentiation of these MSCs, bone marrow MSCs show more extensive bone forming capability than adipose MSCs. Thus, the bone marrow MSCs are useful for bone tissue regeneration. However, the MSCs show limited proliferation and differentiation capabilities that hindered clinical applications in some cases. Recent advances reveal that transduction of plural transcription factors into human adult cells results in generation of new type of stem cells called induced pluripotent stem cells (iPS cells). A drawback of the iPS cells for clinical applications is tumor formation after their in vivo implantation; therefore it is difficult to use iPS cells for the treatment. To circumvent the problem, we transduced a single factor of either SOX2 or NANOG into the MSCs and found high proliferation as well as osteogenic differentiation capabilities of the MSCs. The stem cells could be combined with bioceramics for clinical applications. Here, we summarize our recent technologies using adult stem cells in viewpoints of bone tissue regeneration.

  4. Elaboration de biocéramiques phosphocalciques Processing of calcium phosphate bioceramics

    Directory of Open Access Journals (Sweden)

    Champion Eric

    2013-11-01

    Full Text Available Les céramiques phosphocalciques (hydroxyapatite, phosphate tricalcique sont couramment utilisées comme implants synthétiques en substitution osseuse. Le développement de nouveaux implants céramiques aux performances accrues nécessite la maîtrise de nombreux paramètres chimiques et physiques intervenant dans leurs procédés d'élaboration : synthèse de poudres spécifiques, mise en forme d'architectures complexes contrôlées, frittage et fonctionnalisation. Cette contribution illustre à travers quelques exemples les travaux menés dans le domaine des procédés d'élaboration de ces biocéramiques phosphocalciques pour des applications en ingénierie des tissus osseux. Calcium phosphate ceramics (hydroxyapatite, tricalcium phosphate are commonly used as synthetic bone graft substitutes. The development of new ceramic implants with improved performances requires the mastering of many chemical and physical parameters involved in their processing: synthesis of specific powders, shaping of complex architectures, sintering and functionalization. This paper illustrates a few examples of the work in the field of processes of these calcium phosphate bioceramics for applications in bone tissue engineering.

  5. TOPICAL REVIEW: Stem cell technology using bioceramics: hard tissue regeneration towards clinical application

    Science.gov (United States)

    Ohnishi, Hiroe; Oda, Yasuaki; Ohgushi, Hajime

    2010-02-01

    Mesenchymal stem cells (MSCs) are adult stem cells which show differentiation capabilities toward various cell lineages. We have already used MSCs for treatments of osteoarthritis, bone necrosis and bone tumor. For this purpose, culture expanded MSCs were combined with various ceramics and then implanted. Because of rejection response to allogeneic MSC implantation, we have utilized patients' own MSCs for the treatment. Bone marrow is a good cell source of MSCs, although the MSCs also exist in adipose tissue. When comparing osteogenic differentiation of these MSCs, bone marrow MSCs show more extensive bone forming capability than adipose MSCs. Thus, the bone marrow MSCs are useful for bone tissue regeneration. However, the MSCs show limited proliferation and differentiation capabilities that hindered clinical applications in some cases. Recent advances reveal that transduction of plural transcription factors into human adult cells results in generation of new type of stem cells called induced pluripotent stem cells (iPS cells). A drawback of the iPS cells for clinical applications is tumor formation after their in vivo implantation; therefore it is difficult to use iPS cells for the treatment. To circumvent the problem, we transduced a single factor of either SOX2 or NANOG into the MSCs and found high proliferation as well as osteogenic differentiation capabilities of the MSCs. The stem cells could be combined with bioceramics for clinical applications. Here, we summarize our recent technologies using adult stem cells in viewpoints of bone tissue regeneration.

  6. Structure and functionalization of mesoporous bioceramics for bone tissue regeneration and local drug delivery.

    Science.gov (United States)

    Vallet-Regí, María; Izquierdo-Barba, Isabel; Colilla, Montserrat

    2012-03-28

    This review article describes the importance of structure and functionalization in the performance of mesoporous silica bioceramics for bone tissue regeneration and local drug delivery purposes. Herein, we summarize the pivotal features of mesoporous bioactive glasses, also known as 'templated glasses' (TGs), which present chemical compositions similar to those of conventional bioactive sol-gel glasses and the added value of an ordered mesopore arrangement. An in-depth study concerning the possibility of tailoring the structural and textural characteristics of TGs at the nanometric scale and their influence on bioactive behaviour is discussed. The highly ordered mesoporous arrangement of cavities allows these materials to confine drugs to be subsequently released, acting as drug delivery devices. The functionalization of mesoporous silica walls has been revealed as the cornerstone in the performance of these materials as controlled release systems. The synergy between the improved bioactive behaviour and local sustained drug release capability of mesostructured materials makes them suitable to manufacture three-dimensional macroporous scaffolds for bone tissue engineering. Finally, this review tackles the possibility of covalently grafting different osteoinductive agents to the scaffold surface that act as attracting signals for bone cells to promote the bone regeneration process.

  7. Bioceramic coating of hydroxyapatite on titanium substrate with Nd-YAG laser

    Energy Technology Data Exchange (ETDEWEB)

    Cheng, Gary J. [School of Mechanical and Materials Engineering Washington State University, Pullman, WA 99164 (United States)]. E-mail: cheng1@wsu.edu; Pirzada, Daniel [School of Mechanical and Materials Engineering Washington State University, Pullman, WA 99164 (United States); Cai, M. [Physics Department Washington State University, Pullman, WA 99164-2814 (United States); Mohanty, Pravansu [Department of Mechanical Engineering, University of Michigan - Dearborn, Dearborn, MI (United States); Bandyopadhyay, Amit [School of Mechanical and Materials Engineering Washington State University, Pullman, WA 99164 (United States)

    2005-06-15

    The ability to bond to bone tissue is a unique property of bioactive ceramics. Hydroxyapatite (HAp) is one of the potential bioceramics candidates due to its superior bio-compatibility. Significant effort has been devoted to coat HAp ceramics on metallic substrates. Most of these processes, such as ion-beam sputter coating, thermal spraying, and flame spraying, are high temperature line of sight processes, which suffer from undesirable phase formation and weak metal/HAP bonding strength. This paper presents a unique process to coat HAp powders on titanium substrates at low temperature and enhance the coating/substrate interface by laser surface engineering. Nd-YAG laser transmits HAp powders and the laser power is absorbed by titanium substrate to produce a thin layer of molten region. During coating process, HAp powders are kept at low temperature before they are entrapped in metallic layer. Scanning electron microscope (SEM) was used to investigate the microstructure of coating; the chemical composition of the coating is determined by energy dispersive spectrometry (EDS). Mechanical properties of the interface between coating and Ti substrate were investigated by nanoindentation.

  8. Evaluation of host inflammatory responses of β-tricalcium phosphate bioceramics caused by calcium pyrophosphate impurity using a subcutaneous model.

    Science.gov (United States)

    Lin, Kaili; Yuan, Wei; Wang, Lu; Lu, Jianxi; Chen, Lei; Wang, Zhen; Chang, Jiang

    2011-11-01

    Implantation of synthetic materials into body elicits inflammatory host responses that limit medical device integration and biological performance. Since the effective use of biomaterials in vivo requires good biocompatibility and bio-functionality, it is vital that we assess the inflammatory reactions provoked by various implanted biomaterials. In chemical precipitation of β-tricalcium phosphate [β-Ca₃(PO₄)₂, β-TCP], the impurity of calcium pyrophosphate (Ca₂P₂O₇, CPP) will easily appear if the preparation conditions are not well controlled. To test the influences of CCP-impurity on the biocompatibility of the material, four groups of β-TCP ceramic samples doped with 0.5-10 wt % of CCP impurity, and pure β-TCP and CCP samples were fabricated and implanted in rat subcutaneous site for one, two, and four weeks. The host tissue responses to the ceramics were evaluated by histomorphometric analysis, and the results were compared with pure β-TCPbioceramics. The results show that the CPP impurity can elicit and stimulate the inflammatory responses at the tissue/implant interface. Moreover, with the increase of CPP doping amount, the inflammation increases apparently. However, the pure β-TCP bioceramics only present slight post-implantation inflammatory responses. The influence of the CPP doping on the inflammatory responses is mainly related to a microparticles release because of an insufficient sintering of β-TCP by CPP doping. The microparticle release could be at the origin of local inflammation and cell/tissue damages. Therefore, to obtain perfect biocompatibility and high quality β-TCP bioceramics, it is important to avoid and control the CPP impurity in the preparation of β-TCP powders and bioceramics.

  9. Confocal Raman and electronic microscopy studies on the topotactic conversion of calcium carbonate from Pomacea lineate shells into hydroxyapatite bioceramic materials in phosphate media.

    Science.gov (United States)

    dePaula, S M; Huila, M F G; Araki, K; Toma, H E

    2010-12-01

    Conversion of Pomacea lineate shells into hydroxyapatite (HA) bioceramic materials was investigated by their in vitro treatment with phosphate solutions, at room temperature. Confocal Raman microscopy revealed that the conversion proceeds at distinct rates through the nacreous or periostracum sides of the shell. The conversion can be accelerated using powdered samples, yielding biocompatible materials of great interest in biomedicine.

  10. Processing and characterization of multi-cellular monolithic bioceramics for bone regenerative scaffolds

    Energy Technology Data Exchange (ETDEWEB)

    Ari-Wahjoedi, Bambang, E-mail: bambang-ariwahjoedi@petronas.com.my [Department of Fundamental and Applied Sciences, Universiti Teknologi PETRONAS, Bandar Seri Iskandar, 31750 Tronoh, Perak Darul Ridzuan (Malaysia); Centre for Intelligent Signal and Imaging Research, Universiti Teknologi PETRONAS, Bandar Seri Iskandar (Malaysia); Ginta, Turnad Lenggo [Department of Mechanical Engineering, Universiti Teknologi PETRONAS, Bandar Seri Iskandar, 31750 Tronoh, Perak Darul Ridzuan (Malaysia); Centre for Intelligent Signal and Imaging Research, Universiti Teknologi PETRONAS, Bandar Seri Iskandar, 31750 Tro (Malaysia); Parman, Setyamartana [Department of Mechanical Engineering, Universiti Teknologi PETRONAS, Bandar Seri Iskandar, 31750 Tronoh, Perak Darul Ridzuan (Malaysia); Abustaman, Mohd Zikri Ahmad [Kebabangan Petroleum Operating Company Sdn Bhd, Lvl. 52, Tower 2, PETRONAS Twin Towers, KLCC, 50088 Kuala Lumpur (Malaysia)

    2014-10-24

    Multicellular monolithic ceramic body is a ceramic material which has many gas or liquid passages partitioned by thin walls throughout the bulk material. There are many currently known advanced industrial applications of multicellular ceramics structures i.e. as supports for various catalysts, electrode support structure for solid oxide fuel cells, refractories, electric/electronic materials, aerospace vehicle re-entry heat shields and biomaterials for dental as well as orthopaedic implants by naming only a few. Multicellular ceramic bodies are usually made of ceramic phases such as mullite, cordierite, aluminum titanate or pure oxides such as silica, zirconia and alumina. What make alumina ceramics is excellent for the above functions are the intrinsic properties of alumina which are hard, wear resistant, excellent dielectric properties, resists strong acid and alkali attacks at elevated temperatures, good thermal conductivities, high strength and stiffness as well as biocompatible. In this work the processing technology leading to truly multicellular monolithic alumina ceramic bodies and their characterization are reported. Ceramic slip with 66 wt.% solid loading was found to be optimum as impregnant to the polyurethane foam template. Mullitic ceramic composite of alumina-sodium alumino disilicate-Leucite-like phases with bulk and true densities of 0.852 and 1.241 g cm{sup −3} respectively, pore linear density of ±35 cm{sup −1}, linear and bulk volume shrinkages of 7-16% and 32 vol.% were obtained. The compressive strength and elastic modulus of the bioceramics are ≈0.5-1.0 and ≈20 MPa respectively.

  11. Analysis of radiopacity, pH and cytotoxicity of a new bioceramic material

    Directory of Open Access Journals (Sweden)

    Letícia Chaves de SOUZA

    2015-08-01

    Full Text Available AbstractObjective RetroMTA® is a new hydraulic bioceramic indicated for pulp capping, perforations or root resorption repair, apexification and apical surgery. The aim of this study was to compare the radiopacity, pH variation and cytotoxicity of this material to ProRoot® MTA.Material and Methods Mixed cements were exposed to a digital x-ray along with an aluminum stepwedge for the radiopacity assay. pH values were verified after incubation period of 3, 24, 48, 72 and 168 hours. The cytotoxicity of each cement was tested on human periodontal ligament fibroblasts using a multiparametric assay. Data analysis was performed using ANOVA and Tukey’spost hoc in GraphPad Prism.Results ProRoot® MTA had higher radiopacity than RetroMTA®(p0.05 although pH levels of both materials reduced over time. Both ProRoot® MTA and RetroMTA® allowed for significantly higher cell viability when compared with the positive control (p<0.001. No statistical difference was observed between ProRoot® MTA and RetroMTA® cytotoxicity level in all test parameters, except for the ProRoot® MTA 48-hour extract media in the NR assay (p<0.05.Conclusion The current study provides new data about the physicochemical and biological properties of Retro® MTA concerning radiopacity, pH and cytotoxic effects on human periodontal ligaments cells. Based on our findings, RetroMTA® meets the radiopacity requirements standardized by ANSI/ADA number 572, and similar pH values and biocompatibility to ProRoot® MTA. Further studies should be performed to evaluate additional properties of this new material.

  12. First-Row Transition Metal Doping in Calcium Phosphate Bioceramics: A Detailed Crystallographic Study

    Directory of Open Access Journals (Sweden)

    Guillaume Renaudin

    2017-01-01

    Full Text Available Doped calcium phosphate bioceramics are promising materials for bone repair surgery because of their chemical resemblance to the mineral constituent of bone. Among these materials, BCP samples composed of hydroxyapatite (Ca10(PO46(OH2 and β-TCP (Ca3(PO42 present a mineral analogy with the nano-multi-substituted hydroxyapatite bio-mineral part of bones. At the same time, doping can be used to tune the biological properties of these ceramics. This paper presents a general overview of the doping mechanisms of BCP samples using cations from the first-row transition metals (from manganese to zinc, with respect to the applied sintering temperature. The results enable the preparation of doped synthetic BCP that can be used to tailor biological properties, in particular by tuning the release amounts upon interaction with biological fluids. Intermediate sintering temperatures stabilize the doping elements in the more soluble β-TCP phase, which favors quick and easy release upon integration in the biological environment, whereas higher sintering temperatures locate the doping elements in the weakly soluble HAp phase, enabling a slow and continuous supply of the bio-inspired properties. An interstitial doping mechanism in the HAp hexagonal channel is observed for the six investigated cations (Mn2+, Fe3+, Co2+, Ni2+, Cu2+ and Zn2+ with specific characteristics involving a shift away from the center of the hexagonal channel (Fe3+, Co2+, cationic oxidation (Mn3+, Co3+, and also cationic reduction (Cu+. The complete crystallochemical study highlights a complex HAp doping mechanism, mainly realized by an interstitial process combined with calcium substitution for the larger cations of the series leading to potentially calcium deficient HAp.

  13. Partial Pulpotomy of Immature Teeth with Apical Periodontitis using Bioceramics and Mineral Trioxide Aggregate: A Report of Three Cases.

    Science.gov (United States)

    Jiang, Shan; Wu, Hao; Zhang, Cheng Fei

    2016-06-01

    Pulpal necrosis of an immature permanent tooth with an open apex poses a challenge for the clinician. The conventional apexification technique using calcium hydroxide has yielded short-term success, but this technique has inevitable shortcomings. Hence, this case series aimed to evaluate the effectiveness of using bioceramics (iRoot BP) or mineral trioxide aggregate (MTA) for partial pulpotomies. Three boys aged 9 to 11 years old presented with partial pulp necrosis and symptomatic apical periodontitis of the mandibular right and left second premolar. The involved teeth were treated with a partial pulpotomy using either iRoot BP (case 1 and 2) or MTA (case 3). At the 8-month follow-up, no abnormal clinical signs or symptoms were observed. Periapical radiographs revealed a significant reduction in periapical radiolucency, a marked increase in the root canal wall thickness and ongoing closure of the apical opening. The bioceramic material (iRoot BP) and MTA both produced successful outcomes in the partial pulpotomy of immature teeth with partial pulp necrosis and apical periodontitis. However, iRoot BP was superior in terms of ease of clinical application, and would therefore be a better treatment alternative than MTA.

  14. Promotion of Dental Pulp Cell Migration and Pulp Repair by a Bioceramic Putty Involving FGFR-mediated Signaling Pathways.

    Science.gov (United States)

    Zhang, J; Zhu, L X; Cheng, X; Lin, Y; Yan, P; Peng, B

    2015-06-01

    Mineral trioxide aggregate is the currently recommended material of choice for clinical pulp repair despite several disadvantages, including handling inconvenience. Little is known about the signaling mechanisms involved in bioceramic-mediated dental pulp repair-particularly, dental pulp cell (DPC) migration. This study evaluated the effects of iRoot BP Plus, a novel ready-to-use nanoparticulate bioceramic putty, on DPC migration in vitro and pulp repair in vivo, focusing on possible involvement of fibroblast growth factor receptor (FGFR)-related signaling, including mitogen-activated protein kinase and Akt pathways. Treatment with iRoot BP Plus extracts enhanced horizontal and vertical migration of DPCs, which was comparable with the effects induced by mineral trioxide aggregate extracts. The DPCs exposed to iRoot BP Plus extracts demonstrated no evident apoptosis. Importantly, treatment with iRoot BP Plus extracts resulted in rapid activation of FGFR, p38 mitogen-activated protein kinase, extracellular signal-regulated kinase (ERK) 1/2, c-Jun-N-terminal kinase (JNK), and Akt signaling in DPCs. Confocal immunofluorescence staining revealed that iRoot BP Plus stimulated focal adhesion formation and stress fiber assembly in DPCs, in addition to upregulating the expression of focal adhesion molecules, including p-focal adhesion kinase, p-paxillin, and vinculin. Moreover, activation of FGFR, ERK, JNK, and Akt were found to mediate the upregulated expression of focal adhesion molecules, stress fiber assembly, and enhanced DPC migration induced by iRoot BP Plus. Consistent with the in vitro results, we observed induction of homogeneous dentin bridge formation and expression of p-focal adhesion kinase, p-FGFR, p-ERK 1/2, p-JNK, and p-Akt near injury sites by iRoot BP Plus in an in vivo pulp repair model. These data demonstrate that iRoot BP Plus can promote DPC migration and pulp repair involving the FGFR-mediated ERK 1/2, JNK, and Akt pathways. These findings provide

  15. Contrasting the beam interaction characteristics of selected lasers with a partially stabilised zirconia (PSZ) bio-ceramic

    OpenAIRE

    Lawrence, Jonathan

    2002-01-01

    Differences in the beam interaction characteristics of a CO2 laser, a Nd:YAG laser, a high power diode laser (HPDL) and an excimer laser with a partially stabilised zirconia (PSZ) bio-ceramic have been studied. A derivative of Beer-Lambert’s law was applied and the laser beam absorption lengths of the four lasers were calculated as 33.55 x 10-3 cm for the CO2 laser, 18.22 x 10-3 cm for the Nd:YAG laser, 17.17 x 10-3 cm for the HPDL and 8.41 x 10-6 cm for the excimer laser. It was determined g...

  16. Mechanical and biological properties of the micro-/nano-grain functionally graded hydroxyapatite bioceramics for bone tissue engineering.

    Science.gov (United States)

    Zhou, Changchun; Deng, Congying; Chen, Xuening; Zhao, Xiufen; Chen, Ying; Fan, Yujiang; Zhang, Xingdong

    2015-08-01

    Functionally graded materials (FGM) open the promising approach for bone tissue repair. In this study, a novel functionally graded hydroxyapatite (HA) bioceramic with micrograin and nanograin structure was fabricated. Its mechanical properties were tailored by composition of micrograin and nanograin. The dynamic mechanical analysis (DMA) indicated that the graded HA ceramics had similar mechanical property compared to natural bones. Their cytocompatibility was evaluated via fluorescent microscopy and MTT colorimetric assay. The viability and proliferation of rabbit bone marrow mesenchymal stem cells (BMSCs) on ceramics indicated that this functionally graded HA ceramic had better cytocompatibility than conventional HA ceramic. This study demonstrated that functionally graded HA ceramics create suitable structures to satisfy both the mechanical and biological requirements of bone tissues.

  17. The effect of pore size on tissue ingrowth and neovascularization in porous bioceramics of controlled architecture in vivo

    Energy Technology Data Exchange (ETDEWEB)

    Bai Feng; Zhang Jinkang; Wang Zhen; Liu Jian; Meng Guolin; Dong Xin [Institute of Orthopedic Surgery, Xijing Hospital, Fourth Military Medical University, Xi' an 710032 (China); Lu Jianxi; Chang Jiang, E-mail: baifeng_fmmu@126.com [Shanghai Institute of Ceramics, Chinese Academy of Sciences, Shanghai 200050 (China)

    2011-02-15

    The purpose of this study was to investigate the role of pore size on tissue ingrowth and neovascularization in porous bioceramics under the accurate control of the pore parameters. For that purpose, {beta}-tricalcium phosphate ({beta}-TCP) cylinders with four different macropore sizes (300-400, 400-500, 500-600 and 600-700 {mu}m) but the same interconnection size (120 {mu}m) and unchangeable porosity were implanted into fascia lumbodorsalis in rabbits. The fibrous tissues and blood vessels formed in scaffolds were observed histologically and histomorphometrically. The vascularization of the porous bioceramics was analyzed by single-photon emission computed tomography (SPECT). It is found that pore size as an important parameter of a porous structure plays an important role in tissue infiltration into porous biomaterial scaffolds. The amount of fibrous tissue ingrowth increases with the decrease of the pore size. In four kinds of scaffolds with different macropore sizes (300-400, 400-500, 500-600 and 600-700 {mu}m) and a constant interconnection size of 120 {mu}m, the areas of fibrous tissue (%) were 60.5%, 52.2%, 41.3% and 37.3%, respectively, representing a significant decrease at 4 weeks (P < 0.01). The pore size of a scaffold is closely related to neovascularization of macroporous biomaterials implanted in vivo. A large pore size is beneficial for the growth of blood vessels, and the diameter of a pore smaller than 400 {mu}m limits the growth of blood vessels and results in a smaller blood vessel diameter.

  18. Silicate bioceramics enhanced vascularization and osteogenesis through stimulating interactions between endothelia cells and bone marrow stromal cells.

    Science.gov (United States)

    Li, Haiyan; Xue, Ke; Kong, Ni; Liu, Kai; Chang, Jiang

    2014-04-01

    The facts that biomaterials affect the behavior of single type of cells have been widely accepted. However, the effects of biomaterials on cell-cell interactions have rarely been reported. Bone tissue engineering involves osteoblastic cells (OCs), endothelial cells (ECs) and the interactions between OCs and ECs. It has been reported that silicate biomaterials can stimulate osteogenic differentiation of OCs and vascularization of ECs. However, the effects of silicate biomaterials on the interactions between ECs and OCs during vascularization and osteogenesis have not been reported, which are critical for bone tissue regeneration in vivo. Therefore, this study aimed to investigate the effects of calcium silicate (CS) bioceramics on interactions between human umbilical vein endothelial cells (HUVECs) and human bone marrow stromal cells (HBMSCs) and on stimulation of vascularization and osteogenesis in vivo through combining co-cultures with CS containing scaffolds. Specifically, the effects of CS on the angiogenic growth factor VEGF, osteogenic growth factor BMP-2 and the cross-talks between VEGF and BMP-2 in the co-culture system were elucidated. Results showed that CS stimulated co-cultured HBMSCs (co-HBMSCs) to express VEGF and the VEGF activated its receptor KDR on co-cultured HUVECs (co-HUVECs), which was also up-regulated by CS. Then, BMP-2 and nitric oxide expression from the co-HUVECs were stimulated by CS and the former stimulated osteogenic differentiation of co-HBMSCs while the latter stimulated vascularization of co-HVUECs. Finally, the poly(lactic-co-glycolic acid)/CS composite scaffolds with the co-cultured HBMSCs and HUVECs significantly enhanced vascularization and osteogenic differentiation in vitro and in vivo, which indicates that it is a promising way to enhance bone regeneration by combining scaffolds containing silicate bioceramics and co-cultures of ECs and OCs.

  19. The effect of pore size on tissue ingrowth and neovascularization in porous bioceramics of controlled architecture in vivo.

    Science.gov (United States)

    Feng, Bai; Jinkang, Zhang; Zhen, Wang; Jianxi, Lu; Jiang, Chang; Jian, Liu; Guolin, Meng; Xin, Dong

    2011-02-01

    The purpose of this study was to investigate the role of pore size on tissue ingrowth and neovascularization in porous bioceramics under the accurate control of the pore parameters. For that purpose, β-tricalcium phosphate (β-TCP) cylinders with four different macropore sizes (300-400, 400-500, 500-600 and 600-700 µm) but the same interconnection size (120 µm) and unchangeable porosity were implanted into fascia lumbodorsalis in rabbits. The fibrous tissues and blood vessels formed in scaffolds were observed histologically and histomorphometrically. The vascularization of the porous bioceramics was analyzed by single-photon emission computed tomography (SPECT). It is found that pore size as an important parameter of a porous structure plays an important role in tissue infiltration into porous biomaterial scaffolds. The amount of fibrous tissue ingrowth increases with the decrease of the pore size. In four kinds of scaffolds with different macropore sizes (300-400, 400-500, 500-600 and 600-700 µm) and a constant interconnection size of 120 µm, the areas of fibrous tissue (%) were 60.5%, 52.2%, 41.3% and 37.3%, respectively, representing a significant decrease at 4 weeks (P < 0.01). The pore size of a scaffold is closely related to neovascularization of macroporous biomaterials implanted in vivo. A large pore size is beneficial for the growth of blood vessels, and the diameter of a pore smaller than 400 µm limits the growth of blood vessels and results in a smaller blood vessel diameter.

  20. Influence of surface porosity and pH on bacterial adherence to hydroxyapatite and biphasic calcium phosphate bioceramics.

    Science.gov (United States)

    Kinnari, Teemu J; Esteban, Jaime; Martin-de-Hijas, Nieves Z; Sánchez-Muñoz, Orlando; Sánchez-Salcedo, Sandra; Colilla, Montserrat; Vallet-Regí, María; Gomez-Barrena, Enrique

    2009-01-01

    Hydroxyapatite (HA) and biphasic calcium phosphate (BCP) ceramic materials are widely employed as bone substitutes due to their porous and osteoconductive structure. Their porosity and the lowering of surrounding pH as a result of surgical trauma may, however, predispose these materials to bacterial infections. For this reason, the influence of porosity and pH on the adherence of common Gram-positive bacteria to the surfaces of these materials requires investigation. Mercury intrusion porosimetry measurements revealed that the pore size distribution of both bioceramics had, on a logarithmic scale, a sinusoidal frequency distribution ranging from 50 to 300 nm, with a mean pore diameter of 200 nm. Moreover, total porosity was 20 % for HA and 50 % for BCP. Adherence of Staphylococcus aureus and Staphylococcus epidermidis was studied at a physiological pH of 7.4 and at a pH simulating bone infection of 6.8. Moreover, the effect of pH on the zeta potential of HA, BCP and of both staphylococci was evaluated. Results showed that when pH decreased from 7.4 to 6.8, the adherence of both staphylococci to HA and BCP surfaces decreased significantly, although at the same time the negative zeta-potential values of the ceramic surfaces and both bacteria diminished. At both pH values, the number of S. aureus adhered to the HA surface appeared to be lower than that for BCP. A decrease in pH to 6.8 reduced the adherence of both bacterial species (mean 57 %). This study provides evidence that HA and BCP ceramics do not have pores sufficiently large to allow the internalization of staphylococci. Their anti-adherent properties seemed to improve when pH value decreased, suggesting that HA and BCP bioceramics are not compromised upon orthopaedic use.

  1. Hierarchical bioceramic scaffolds with 3D-plotted macropores and mussel-inspired surface nanolayers for stimulating osteogenesis

    Science.gov (United States)

    Xu, Mengchi; Zhai, Dong; Xia, Lunguo; Li, Hong; Chen, Shiyi; Fang, Bing; Chang, Jiang; Wu, Chengtie

    2016-07-01

    The hierarchical structure of biomaterials plays an important role in the process of tissue reconstruction and regeneration. 3D-plotted scaffolds have been widely used for bone tissue engineering due to their controlled macropore structure and mechanical properties. However, the lack of micro- or nano-structures on the strut surface of 3D-plotted scaffolds, especially for bioceramic scaffolds, limits their biological activity. Inspired by the adhesive versatility of mussels and the active ion-chelating capacity of polydopamine, we set out to prepare a hierarchical bioceramic scaffold with controlled macropores and mussel-inspired surface nanolayers by combining the 3D-plotting technique with the polydopamine/apatite hybrid strategy in order to synergistically accelerate the osteogenesis and angiogenesis. β-Tricalcium phosphate (TCP) scaffolds were firstly 3D-plotted and then treated in dopamine-Tris/HCl and dopamine-SBF solutions to obtain TCP-DOPA-Tris and TCP-DOPA-SBF scaffolds, respectively. It was found that polydopamine/apatite hybrid nanolayers were formed on the surface of both TCP-DOPA-Tris and TCP-DOPA-SBF scaffolds and TCP-DOPA-SBF scaffolds induced apatite mineralization for the second time during the cell culture. As compared to TCP scaffolds, both TCP-DOPA-Tris and TCP-DOPA-SBF scaffolds significantly promoted the osteogenesis of bone marrow stromal cells (BMSCs) as well as the angiogenesis of human umbilical vein endothelial cells (HUVECs), and the TCP-DOPA-SBF group presented the highest in vitro osteogenic/angiogenic activity among the three groups. Furthermore, both TCP-DOPA-Tris and TCP-DOPA-SBF scaffolds significantly improved the formation of new bone in vivo as compared to TCP scaffolds without a nanostructured surface. Our results suggest that the utilization of a mussel-inspired Ca, P-chelated polydopamine nanolayer on 3D-plotted bioceramic scaffolds is a viable and effective strategy to construct a hierarchical structure for synergistically

  2. The effect of calcium silicate on in vitro physiochemical properties and in vivo osteogenesis, degradability and bioactivity of porous β-tricalcium phosphate bioceramics.

    Science.gov (United States)

    Liu, Shen; Jin, Fangchun; Lin, Kaili; Lu, Jianxi; Sun, Jiao; Chang, Jiang; Dai, Kerong; Fan, Cunyi

    2013-04-01

    Porous β-tricalcium phosphate(TCP)/calcium silicate(CS) composite bioceramics with different weight proportions were prepared to investigate the in vitro effects of CS on the physiochemical properties of TCP and the in vivo effects of CS on the degradability, osteogenesis and bioactivity of TCP. The physiochemical results showed that the addition of CS to porous TCP resulted in a looser and rougher surface and a lower solid density, compressive strength and Young's modulus and a lower pH value as compared to pure CS without any chemical interaction between the TCP and the CS. The in vivo study showed that the material degradation of porous TCP/CS composite bioceramics was slower than that of pure CS, although the osteogenesis, degradability and bioactivity were significantly increased in the long term. Thereafter, the introduction of CS into porous TCP bioceramics is an effective way to prepare bioactive bone grafting scaffolds for clinical use and to control properties such as in vivo degradability and osteoinduction of TCP.

  3. Osteoblast interaction with laser cladded HA and SiO{sub 2}-HA coatings on Ti-6Al-4V

    Energy Technology Data Exchange (ETDEWEB)

    Yang Yuling [Department of Physics, Northeastern University, Shenyang 110004 (China); Department of Materials Science and Engineering, University of Tennessee, Knoxville, TN 37996 (United States); Serpersu, Kaan [Department of Materials Science and Engineering, University of Tennessee, Knoxville, TN 37996 (United States); He Wei, E-mail: whe5@utk.edu [Department of Materials Science and Engineering, University of Tennessee, Knoxville, TN 37996 (United States); Department of Mechanical, Aerospace and Biomedical Engineering, University of Tennessee, Knoxville, TN 37996 (United States); Paital, Sameer R. [Department of Materials Science and Engineering, University of Tennessee, Knoxville, TN 37996 (United States); Dahotre, Narendra B. [Department of Materials Science and Engineering, University of North Texas, Denton, TX 76207 (United States)

    2011-12-01

    In order to improve the bioactivity and biocompatibility of titanium endosseous implants, the morphology and composition of the surfaces were modified. Polished Ti-6Al-4V substrates were coated by a laser cladding process with different precursors: 100 wt.% HA and 25 wt.% SiO{sub 2}-HA. X-ray diffraction of the laser processed samples showed the presence of CaTiO{sub 3}, Ca{sub 3}(PO{sub 4}){sub 2}, and Ca{sub 2}SiO{sub 4} phases within the coatings. From in vitro studies, it was observed that compared to the unmodified substrate all laser cladded samples presented improved cellular interactions and bioactivity. The samples processed with 25 wt.% SiO{sub 2}-HA precursor showed a significantly higher HA precipitation after immersion in simulated body fluid than 100 wt.% HA precursor and titanium substrates. The in vitro biocompatibility of the laser cladded coatings and titanium substrate was investigated by culturing of mouse MC3T3-E1 pre-osteoblast cell line and analyzing the cell viability, cell proliferation, and cell morphology. A significantly higher cell attachment and proliferation rate were observed for both laser cladded 100 wt.% HA and 25 wt.% SiO{sub 2}-HA samples. Compared to 100 wt.% HA sample, 25 wt.% SiO{sub 2}-HA samples presented a slightly improved cellular interaction due to the addition of SiO{sub 2}. The staining of the actin filaments showed that the laser cladded samples induced a normal cytoskeleton and well-developed focal adhesion contacts. Scanning electron microscopic image of the cell cultured samples revealed better cell attachment and spreading for 25 wt.% SiO{sub 2}-HA and 100 wt.% HA coatings than titanium substrate. These results suggest that the laser cladding process improves the bioactivity and biocompatibility of titanium. The observed biological improvements are mainly due to the coating induced changes in surface chemistry and surface morphology. Highlights: {yields} Laser cladding of Ti alloys with bioceramics creates new

  4. Surface microhardness of different thicknesses of a premixed bioceramic material with or without the application of a moist cotton pellet

    Directory of Open Access Journals (Sweden)

    Noushin Shokouhinejad

    2016-01-01

    Full Text Available Background: This study was conducted to assess the effect of thickness and hydration condition on the surface microhardness of Endosequence Root Repair Material putty (ERRM; Brasseler USA, Savannah, GA, a premixed bioceramic material. Materials and Methods: Polymethyl methacrylate cylindrical molds with an internal diameter of 4 mm and three heights of 2, 4, and 6 mm were fabricated. In Group 1 (dry condition, the molds with heights of 2, 4, and 6 mm (10 molds of each were filled with ERRM. In Groups 2 and 3 (wet condition, a distilled water- or phosphate-buffered saline (PBS-moistened cotton pellet was placed directly on the upper surface of ERRM, respectively. The lower surface of ERRM was in contact with floral foams soaked with human blood. After 4 days, Vickers microhardness of the upper surface of ERRM was tested. The data were analyzed using two-way analysis of variance. Significance level was set at P 0.05. Conclusion: Based on the results of this study, it could be concluded that placing a moistened cotton pellet on ERRM putty up to 6 mm thick might be unnecessary to improve its surface microhardness and hydration characteristics.

  5. Bioceramic-collagen scaffolds loaded with human adipose-tissue derived stem cells for bone tissue engineering.

    Science.gov (United States)

    Daei-Farshbaf, Neda; Ardeshirylajimi, Abdolreza; Seyedjafari, Ehsan; Piryaei, Abbas; Fadaei Fathabady, Fatemeh; Hedayati, Mehdi; Salehi, Mohammad; Soleimani, Masoud; Nazarian, Hamid; Moradi, Sadegh-Lotfalah; Norouzian, Mohsen

    2014-02-01

    The combination of bioceramics and stem cells has attracted the interest of research community for bone tissue engineering applications. In the present study, a combination of Bio-Oss(®) and type 1 collagen gel as scaffold were loaded with human adipose-tissue derived mesenchymal stem cells (AT-MSCs) after isolation and characterization, and the capacity of them for bone regeneration was investigated in rat critical size defects using digital mammography, multi-slice spiral computed tomography imaging and histological analysis. 8 weeks after implantation, no mortality or sign of inflammation was observed in the site of defect. According to the results of imaging analysis, a higher level of bone regeneration was observed in the rats receiving Bio-Oss(®)-Gel compared to untreated group. In addition, MSC-seeded Bio-Oss-Gel induced the highest bone reconstruction among all groups. Histological staining confirmed these findings and impressive osseointegration was observed in MSC-seeded Bio-Oss-Gel compared with Bio-Oss-Gel. On the whole, it was demonstrated that combination of AT-MSCs, Bio-Oss and Gel synergistically enhanced bone regeneration and reconstruction and also could serve as an appropriate structure to bone regenerative medicine and tissue engineering application.

  6. Bioceramic/Poly (glycolic-poly (lactic acid composite induces mineralized barrier after direct capping of rat tooth pulp tissue

    Directory of Open Access Journals (Sweden)

    Alfonso Gala-Garcia

    2010-03-01

    Full Text Available The aim of this study was to observe the histopathological pulp response following direct pulp capping of mechanically exposed teeth in rats with a composite of beta-tricalcium phosphate-hydroxyapatite bioceramic (BC and poly (glycolic-poly (lactic acid (PLGA material or a calcium hydroxide [Ca(OH2] material, compared to BC alone and a negative control of water. Pulp of the maxillary molars was exposed, followed by capping with the experimental material. The pulpal tissue response was assessed post-operatively at 1, 7, 14 and 30 d, followed by histological analysis. The Ca(OH2 group exhibited severe acute inflammatory cell infiltration at day 14. However after 30 d, a new hard tissue with macro porous obliteration of the pulp chamber and a characteristic necrotic area had appeared. BC and Ca(OH2 capping were associated with moderate inflammation and dentinal bridge similar. Meanwhile, in the BC/PLGA composite group, there was moderate inflammatory infiltrate and formation of a dense and complete dentinal bridge. In conclusion, the BC/PLGA composite material showed a large zone of tertiary dentin, and effectively reorganized the dentin-pulp complex.

  7. Microstructure and Mechanical Properties of Microwave Sintered ZrO2 Bioceramics with TiO2 Addition.

    Science.gov (United States)

    Kuo, Hsien-Nan; Chou, Jyh-Horng; Liu, Tung-Kuan

    2016-01-01

    The microwave sintered zirconia ceramics with 0, 1, 3, and 5 wt% TiO2 addition at a low sintering temperature of 1300°C and a short holding time of 1 hour were investigated. Effect of contents of TiO2 addition on microstructure and mechanical properties of microwave sintered zirconia bioceramics was reported. In the sintered samples, the main phase is monoclinic zirconia (m-ZrO2) phase and minor phase is tetragonal zirconia (t-ZrO2) phase. The grain sizes increased with increasing the TiO2 contents under the sintering temperature of 1300°C. Although the TiO2 phase was not detected in the XRD pattern, Ti and O elements were detected in the EDS analysis. The presence of TiO2 effectively improved grain growth of the ZrO2 ceramics. The Vickers hardness was in the range of 125 to 300 Hv and increased with the increase of TiO2 contents. Sintering temperature dependence on the Vickers hardness was also investigated from 1150°C to 1300°C, showing the increase of Vickers hardness with the increase of the sintering temperature as well as TiO2 addition.

  8. Microstructure and Mechanical Properties of Microwave Sintered ZrO2 Bioceramics with TiO2 Addition

    Directory of Open Access Journals (Sweden)

    Hsien-Nan Kuo

    2016-01-01

    Full Text Available The microwave sintered zirconia ceramics with 0, 1, 3, and 5 wt% TiO2 addition at a low sintering temperature of 1300°C and a short holding time of 1 hour were investigated. Effect of contents of TiO2 addition on microstructure and mechanical properties of microwave sintered zirconia bioceramics was reported. In the sintered samples, the main phase is monoclinic zirconia (m-ZrO2 phase and minor phase is tetragonal zirconia (t-ZrO2 phase. The grain sizes increased with increasing the TiO2 contents under the sintering temperature of 1300°C. Although the TiO2 phase was not detected in the XRD pattern, Ti and O elements were detected in the EDS analysis. The presence of TiO2 effectively improved grain growth of the ZrO2 ceramics. The Vickers hardness was in the range of 125 to 300 Hv and increased with the increase of TiO2 contents. Sintering temperature dependence on the Vickers hardness was also investigated from 1150°C to 1300°C, showing the increase of Vickers hardness with the increase of the sintering temperature as well as TiO2 addition.

  9. Si/SiGe MMIC's

    Science.gov (United States)

    Luy, Johann-Friedrich; Strohm, Karl M.; Sasse, Hans-Eckard; Schueppen, Andreas; Buechler, Josef; Wollitzer, Michael; Gruhle, Andreas; Schaeffler, Friedrich; Guettich, Ulrich; Klaassen, Andreas

    1995-04-01

    Silicon-based millimeter-wave integrated circuits (SIMMWIC's) can provide new solutions for near range sensor and communication applications in the frequency range above 50 GHz. This paper gives a survey on the state-of-the-art performance of this technology and on first applications. The key devices are IMPATT diodes for mm-wave power generation and detection in the self-oscillating mixer mode, p-i-n diodes for use in switches and phase shifters, and Schottky diodes in detector and mixer circuits. The silicon/silicon germanium heterobipolar transistor (SiGe HBT) with f(sub max) values of more than 90 GHz is now used for low-noise oscillators at Ka-band frequencies. First system applications are discussed.

  10. Preparation and performance of fosfomycin-impregnated bioceramic%复合磷霉素多孔生物陶瓷的制备及其理化性能

    Institute of Scientific and Technical Information of China (English)

    陈文钧; 许耀; 卢建熙; 周则红; 马晓生; 姜建元

    2011-01-01

    Objective To prepare fosfomycin-impregnated bioceramic as a new kind of bone graft.Methods The fosfomycin-impregnated bioceramic was prepared by means of impregnation. After irrigation sterilization, the physical and mechanical properties of fosfomycin-impregnated bioceramic was investigated. Results The physical and mechanical property test showed that the compressive strength was in the normal range after fosfomycin loaded. Conclusions There was no significant differents after the fosfomycin-impregnated bioceramic was prepared.%目的 研制磷霉素多孔生物陶瓷复合体,为临床植骨并减少感染发生提供更好的选择.方法 将磷霉素溶液与多孔生物陶瓷浸泡,风干.测定生物陶瓷吸附磷霉素能力以及测定吸附后多孔生物陶瓷理化性能上的变化.结果 生物陶瓷吸附一定量的磷霉素后,理化性能测试提示其钙磷比和压缩强度仍在正常范围内.结论 生物陶瓷能吸附磷霉素,其理化性质吸附前后没有明显的变化.

  11. Surface phenomena on gel-derived bioceramics - chemical and clinical aspects

    Energy Technology Data Exchange (ETDEWEB)

    Cholewa-Kowalska, K.; Laczka, M. [Univ. of Mining and Metallurgy, Cracow (Poland). Dept. of Glass and Enamels; Osyczka, A. [Jagiellonian Univ., Cracow (Poland). Dept. of Animal Biochemistry

    2002-07-01

    Two gel-derived glass-ceramic biomaterials S2, and A2 were obtained in the form of dense sinters. Chemical compositions of these materials were as follows (mole%): S2: 16CaO, 4P{sub 2}O{sub 5}, 80SiO{sub 2}; A2: 54CaO, 6P{sub 2}O{sub 5}, 40SiO{sub 2}. Biomaterials were produced from gel-derived powders by the hot-pressing process. The A2 material sintered at the temperature 800 C, while the S2 material required higher temperature of sintering (above 1000 C). The obtained biomaterials were tested with respect to the ability of apatite-like layer forming on the surface of these materials. The ability of formation of an apatite-like layer was examined in cell-free ''in vitro'' conditions (contact of materials with simulated body fluid SBF) as well as by the examination of mineral deposits formed on the surface of these materials as a result of bone marrow cell culture. FTIR and EDAX methods were used for the identification of layers forming on the surface of biomaterials. It has been found that only A2 material is able to form an apatite-like layer during immersion in SBF. On the other hand, the mineralised nodules identified as calcium phosphates, formed as a result of bone marrow cell culture, were found on no-bioactive S2 material as well as on A2 sinters. Hence, it may be postulated that the bone-forming behaviour of osteoblastic cells on the biomaterials is not strictly related to their bioactivity. (orig.)

  12. Proliferation and osteogenic differentiation of human periodontal ligament cells on akermanite and β-TCP bioceramics

    Directory of Open Access Journals (Sweden)

    L Xia

    2011-07-01

    Full Text Available The purpose of this study was to investigate the effects of akermanite as compared to β-TCP on attachment, proliferation, and osteogenic differentiation of human periodontal ligament cells (hPDLCs. Scanning electron microscopy (SEM and actin filament labeling were used to reveal attachment and growth of hPDLCs seeded on β-TCP and akermanite ceramic. Cell proliferation was tested by lactic acid production and MTT analysis, while osteogenic differentiation was assayed by alkaline phosphatase (ALP expression and real-time polymerase chain reaction (PCR analysis on markers of osteopontin (OPN, dentin matrix acidic phosphoprotein-1 (DMP-1, and osteocalcin (OCN, and further detected by enzyme-linked immunosorbent analysis (ELISA analysis for OCN expression. Besides, the ions released from akermanite and their effect on hPDLCs was also measured by inductively coupled plasma atomic emission spectroscopy (ICP-AES, MTT analysis, ALP expression and real-time PCR analysis. hPDLCs attached well on both ceramics, but showed better spreading on akermanite. hPDLCs proliferated more rapidly on akermanite than β-TCP. Importantly, osteogenic differentiation of hPDLCs was enhanced on akermanite compared to β-TCP. Besides, Ca, Mg and Si ions were released from akermanite, while only Ca ions were released from β-TCP. Moreover, more pronounced proliferation and higher osteogenic gene expression for hPDLCs cultured with akermanite extract were detected as compared to cells cultured on akermanite. Therefore, akermanite ceramic showed an enhanced effect on proliferation and osteogenic differentiation of hPDLCs, which might be attributed to the release of ions containing Ca, Mg and Si from the material. It is suggested that akermanite ceramics may serve as a potential material for periodontal bone regeneration.

  13. The combined effect of alumina and silica co-doping on the ageing resistance of 3Y-TZP bioceramics.

    Science.gov (United States)

    Samodurova, Anastasia; Kocjan, Andraž; Swain, Michael V; Kosmač, Tomaž

    2015-01-01

    The combined effect of alumina and silica co-doping on the ageing resistance of 3Y-TZP bioceramics was investigated. In order to differentiate between the distinct contributions of two dopants to the overall resistance to low-temperature degradation (LTD), specimens were prepared by infiltration of silica sol into pre-sintered 3Y-TZP pellets, produced from commercially available powders, which were alumina-free or contained 0.05 and 0.25 wt.%. After sintering, specimens were exposed to accelerated ageing in distilled water at 134°C for 6-48 h. X-ray diffraction was applied to quantify the tetragonal-to-monoclinic (t-m) phase transformation associated with the LTD, while a focused ion beam-scanning electron microscopy technique was employed to study the microstructural features in the transformed layer. The results showed that the minor alumina and/or silica additions did not drastically change the densities, grain sizes or mechanical properties of 3Y-TZP, but they did significantly reduce LTD. The addition of either alumina or silica has the potential to influence both the nucleation and the propagation of moisture-induced transformation, but in different ways and to different extents. The co-doped ceramics exhibited predominantly transgranular fracture, reflecting strong grain boundaries (limiting microcracking of the transformed layer), for alumina doping, and rounded grains with a glassy phase at multiple grain junctions (reducing internal stresses) for silica-doped material. These two additives evidently have different dominant mechanisms associated with the deceleration of LTD of 3Y-TZP, but their combination increases resistance to ageing, importantly, without reducing the fracture toughness of this popular biomaterial.

  14. Improvement of the mechanical properties of spark plasma sintered hap bioceramics by decreasing the grain size and by adding multi-walled carbon nanotubes

    Directory of Open Access Journals (Sweden)

    Veljović Đ.

    2013-01-01

    Full Text Available Composites based on HAP and oxidized multi-walled carbon nanotubes (o-MWCNT and monophase HAP materials were processed by spark plasma sintering. Starting from stoichiometric nano-sized HAP powder, monophase bioceramics were obtained with a density close to the theoretical one and with an average grain size of several hundred nanometers to micron dimensions. It was shown that decreasing the sintering temperature resulted in a decrease of the grain size, which affected an increase in the fracture toughness and hardness. The fracture toughness of an HAP/ o-MWCNT bioceramic processed at 900°C for only 5 min was 30 % higher than that of monophase HAP materials obtained under the same conditions. The addition of MWCNT during SPS processing of HAP materials caused a decrease in the grain size to the nano-dimension, which was one of the reasons for the improved mechanical properties. [Projekat Ministarstva nauke Republike Srbije, br. III45019 i FP7-REGPOT-2009-1 NANOTECH FTM, Grant Agreement Number: 245916

  15. Push-out bond strength of gutta-percha with a new bioceramic sealer in the presence or absence of smear layer.

    Science.gov (United States)

    Shokouhinejad, Noushin; Gorjestani, Hedayat; Nasseh, Allen Ali; Hoseini, Atefeh; Mohammadi, Maryam; Shamshiri, Ahmad Reza

    2013-12-01

    The purpose of this study was to compare the bond strength of a new bioceramic sealer (EndoSequence BC Sealer) and AH Plus in the presence or absence of smear layer. Extracted single-rooted human teeth were prepared and randomly divided into four groups. In groups 1 and 3, the root canals were finally irrigated with 5.25% NaOCl and smear layer was not removed, but in groups 2 and 4, the root canals were finally irrigated with 17% EDTA followed by 5.25% NaOCl in order to remove the smear layer. In groups 1 and 2, the root canals were obturated with gutta-percha/AH Plus, but in groups 3 and 4, obturation was performed with gutta-percha/EndoSequence BC Sealer. Push-out bond strength and failure modes were evaluated. The bond strength of gutta-percha/AH Plus and gutta-percha/EndoSequence BC Sealer was not significantly different (P = 0.89). The presence or absence of smear layer did not significantly affect the bond strength of filling materials (P = 0.69). The mode of bond failure was mainly cohesive for all groups. In conclusion, the bond strength of the new bioceramic sealer was equal to that of AH Plus with or without the smear layer.

  16. 生物陶瓷在口腔医学领域的研究进展%The Research Progress of Bioceramic in Stomatology

    Institute of Scientific and Technical Information of China (English)

    孙昌; 孙康宁

    2011-01-01

    Because of its good biocompatibility,bony conduction ability,cell affinity, corrosive resistance, thermal stability and mechanical properties, Bioceramic has a broad prospect of application in stomatology. This paper reviewed the research progress of hydroxyapatite ceramic, zirconia ceramic, alumina ceramic, silicon carbide ceramic, bioglass and related application technology in stomatology, and points out the development trend of bioceramic in stomatology.%生物陶瓷由于具有良好的生物相容性、骨传导特性、与细胞的亲和性、耐腐蚀性、热稳定性及机械性能,在口腔医学领域具有广泛的应用前景。本文对羟基磷灰石生物陶瓷、氧化锆生物陶瓷、氧化铝生物陶瓷、碳化硅陶瓷、生物玻璃及其相关应用技术在口腔医学领域的最新研究进展进行了综述,并给出了生物陶瓷在口腔医学领域的发展趋势。

  17. A novel porous bioceramics scaffold by accumulating hydroxyapatite spherulites for large bone tissue engineering in vivo. II. Construct large volume of bone grafts.

    Science.gov (United States)

    Zhi, Wei; Zhang, Cong; Duan, Ke; Li, Xiaohong; Qu, Shuxin; Wang, Jianxin; Zhu, Zhuoli; Huang, Peng; Xia, Tian; Liao, Ga; Weng, Jie

    2014-08-01

    In vivo engineering of bone autografts using bioceramic scaffolds with appropriate porous structures is a potential approach to prepare autologous bone grafts for the repair of critical-sized bone defects. This study investigated the evolutionary process of osteogenesis, angiogenesis, and compressive strength of bioceramic scaffolds implanted in two non-osseous sites of dogs: the abdominal cavity and the dorsal muscle. Hydroxyapatite (HA) sphere-accumulated scaffolds with controlled porous structures were prepared and placed in the two sites for up to 6 months. Analyses of retrieved scaffolds found that osteogenesis and angiogenesis were faster in scaffolds implanted in dorsal muscles compared with those placed in abdominal cavities. The abdominal cavity, however, can accommodate larger bone grafts with designed shape. Analyses of scaffolds implanted in abdominal cavities [an environment of a low mesenchymal stem cell (MSC) density] further demonstrated that angiogenesis play critical roles during osteogenesis in the scaffolds, presumably by supplying progenitor cells and/or MSCs as seed cells. This study also examined the relationship between the volume of bone grafts and the physiological environment of in vivo bioreactor. These results provide basic information for the selection of appropriate implanting sites and culture time required to engineer autologous bone grafts for the clinical bone defect repair. Based on these positive results, a pilot study has applied the grafts constructed in canine abdominal cavity to repair segmental bone defect in load-bearing sites (limbs).

  18. Human urine-derived stem cells can be induced into osteogenic lineage by silicate bioceramics via activation of the Wnt/β-catenin signaling pathway.

    Science.gov (United States)

    Guan, Junjie; Zhang, Jieyuan; Guo, Shangchun; Zhu, Hongyi; Zhu, Zhenzhong; Li, Haiyan; Wang, Yang; Zhang, Changqing; Chang, Jiang

    2015-07-01

    Human urine-derived stem cells (USCs) have great application potential for cytotherapy as they can be obtained by non-invasive and simple methods. Silicate bioceramics, including calcium silicate (CS), can stimulate osteogenic differentiation of stem cells. However, the effects of silicate bioceramics on osteogenic differentiation of USCs have not been reported. In this study, at first, we investigated the effects of CS ion extracts on proliferation and osteogenic differentiation of USCs, as well as the related mechanism. CS particles were incorporated into poly (lactic-co-glycolic acid) (PLGA) to obtain PLGA/CS composite scaffolds. USCs were then seeded onto these scaffolds, which were subsequently transplanted into nude mice to analyze the osteogenic differentiation of USCs and mineralization of extracellular matrix formed by USCs in vivo. The results showed that CS ion extracts significantly enhanced cell proliferation, alkaline phosphatase (ALP) activity, calcium deposition, and expression of certain osteoblast-related genes and proteins. In addition, cardamonin, a Wnt/β-catenin signaling inhibitor, reduced the stimulatory effects of CS ion extracts on osteogenic differentiation of USCs, indicating that the observed osteogenic differentiation of USCs induced by CS ion extracts involves Wnt/β-catenin signaling pathway. Furthermore, histological analysis showed that PLGA/CS composite scaffolds significantly enhanced the osteogenic differentiation of USCs in vivo. Taken together, these results suggest the therapeutic potential of combining USCs and PLGA/CS scaffolds in bone tissue regeneration.

  19. 与Si工艺兼容的Si/SiGe/Si HBT研究%The Study of Si/SiGe/Si HBT and Its Compatibility with Si Process

    Institute of Scientific and Technical Information of China (English)

    廖小平

    2001-01-01

    我们对Si/SiGe/Si HBT及其Si兼容工艺进行了研究,在研究了一些关键的单项工艺的基础上,提出了五个高速Si/SiGe/Si HBT结构和一个低噪声Si/SiGe/Si HBT结构,并已研制成功台面结构Si/SiGe/Si HBT和低噪声Si/SiGe/Si HBT,为进一步高指标的Si/SiGe/Si HBT的研究建立了基础.

  20. Magnetism and thermal induced characteristics of Fe2O3 content bioceramics

    Science.gov (United States)

    Wu, Chun-Shiang; Hsi, Chi-Shiung; Hsu, Fang-Chi; Wang, Moo-Chin; Chen, Yung-Sheng

    2012-11-01

    Magnetic properties of Li2O-MnO2-CaO-P2O5-SiO2 (LMCPS) glasses doped with various amounts of Fe2O3 were investigated. There is a dramatic change in the magnetic property of pristine LMCPS after the addition of Fe2O3 and crystallized at 850 °C for 4 h. Both the electron paramagnetic resonance and magnetic susceptibility measurements showed that the glass ceramic with 4 at% Fe2O3 exhibited the coexistence of superparamagnetism and ferromagnetism at room temperature. When the Fe2O3 content was higher than 8 at%, the LMCPS glasses showed ferromagnetism behavior. The complex magnetic behavior is due to the distribution of (Li, Mn)ferrite particle sizes driven by the Fe2O3 content. The thermal induced hysteresis loss of the crystallized LMCPS glass ceramics was characterized under an alternating magnetic field. The energy dissipations of the crystallized LMCPS glass ceramics were determined by the concentration and Mn/Fe ratios of Li(Mn, Fe)ferrite phase formed in the glass ceramics.

  1. Magnetism and thermal induced characteristics of Fe{sub 2}O{sub 3} content bioceramics

    Energy Technology Data Exchange (ETDEWEB)

    Wu, Chun-Shiang; Hsi, Chi-Shiung [Department of Materials Science and Engineering, National United University, Miaoli 36003, Taiwan (China); Hsu, Fang-Chi, E-mail: fangchi@nuu.edu.tw [Department of Materials Science and Engineering, National United University, Miaoli 36003, Taiwan (China); Wang, Moo-Chin [Department of Fragrance and Cosmetics, Kaohsiung Medical University, Kaohsiung 807, Taiwan (China); Chen, Yung-Sheng [Department of Materials Science and Engineering, I-Shou University, Kaohsiung 803, Taiwan (China)

    2012-11-15

    Magnetic properties of Li{sub 2}O-MnO{sub 2}-CaO-P{sub 2}O{sub 5}-SiO{sub 2} (LMCPS) glasses doped with various amounts of Fe{sub 2}O{sub 3} were investigated. There is a dramatic change in the magnetic property of pristine LMCPS after the addition of Fe{sub 2}O{sub 3} and crystallized at 850 Degree-Sign C for 4 h. Both the electron paramagnetic resonance and magnetic susceptibility measurements showed that the glass ceramic with 4 at% Fe{sub 2}O{sub 3} exhibited the coexistence of superparamagnetism and ferromagnetism at room temperature. When the Fe{sub 2}O{sub 3} content was higher than 8 at%, the LMCPS glasses showed ferromagnetism behavior. The complex magnetic behavior is due to the distribution of (Li, Mn)ferrite particle sizes driven by the Fe{sub 2}O{sub 3} content. The thermal induced hysteresis loss of the crystallized LMCPS glass ceramics was characterized under an alternating magnetic field. The energy dissipations of the crystallized LMCPS glass ceramics were determined by the concentration and Mn/Fe ratios of Li(Mn, Fe)ferrite phase formed in the glass ceramics. - Highlights: Black-Right-Pointing-Pointer Presence of Fe{sub 2}O{sub 3} in LMCPS glass ceramic promotes the growth of (Li, Mn)ferrite. Black-Right-Pointing-Pointer The amount of Fe{sub 2}O{sub 3} determines the size of (Li,Mn)ferrite particles. Black-Right-Pointing-Pointer Room temperature superparamagnetism was obtained at 4 at% of Fe{sub 2}O{sub 3} addition. Black-Right-Pointing-Pointer In addition, Li(Mn, Fe)ferrite phase contributes to the magnetic energy loss. Black-Right-Pointing-Pointer The largest energy loss is the trade-off between the ferrite content and Mn/Fe ratio.

  2. Bioactivity of Gradient Rare Earths Bioceramic Coating Produced by Wide-Band Laser Cladding%宽带激光熔覆梯度稀土生物陶瓷涂层的生物活性

    Institute of Scientific and Technical Information of China (English)

    李明; 汪震

    2012-01-01

    To decrease thermal crack and to raise bonding strength between substrate and bioceramic coating during laser cladding, a kind of gradient rare earths bioceramics coating is designed. And the rare earth active gradient bioceramic coating with HA and β-TCP on Ti allloy was prepared by using wide-band laser cladding technique. The surface morphologies and microstructure were analyzed by OM, SEM and XRD; the bioceramic coating was immersed in SBF to examine its bioactivity ; and the corrosion resistance of bioceramic was examed by the Electrochemical Analyzer. Results show that the rare earth active bioceramic gradient coatings which have excellent chemical metallurgy bonding at the interface consists of substrate, alloying layer and bioceramic coating. When content of Nd2O3 is up to 0.6wt.%, the amount of HA+β — TCP catalyzed during wide-band laser cladding becomes largest. Bioactivity and corrosion resistance of bioceramic coating is dependent on the amount of HA + β—TCP catalyzed. The largest amount of apatite formed on the surface of gradient bioceramic coating is complied with 0.6wt.% Nd2O3. At the same time, the corrosion resistence is best.%为了减少激光熔覆过程中基材与生物陶瓷涂层之间的热裂纹,提高涂层与基材的结合强度,设计了一种梯度稀土生物陶瓷涂层,采用宽带激光熔覆技术,在TC4钛合金表面制备了含HA+β-TCP活性相的稀土活性梯度生物陶瓷复合涂层.利用SEM、XRD分析手段对涂层形貌、相组成进行了研究;通过模拟体液(SBF)浸泡实验(浸泡7、14 d)考察了生物陶瓷涂层的生物活性;利用电化学分析仪测试了生物活性陶瓷涂层的耐腐蚀性.结果表明,当稀土氧化物Nd2O3添加量为w(Nd2O3) =0.6%时,宽带激光熔覆过程中催化合成HA +3-TCP活性相的数量最多,具有优异的表面形貌;当稀土氧化物Nd2O3添加量为w(Nd2O3)=0.6%时,梯度稀土生物陶瓷涂层在SBF中浸泡不同时间点后表面沉

  3. Preparation and characterization of porous bioceramic layers on pure titanium surfaces obtained by micro-arc oxidation process

    Science.gov (United States)

    Chien, Chi-Sheng; Hung, Yu-Chien; Hong, Ting-Fu; Wu, Chung-Chun; Kuo, Tsung-Yuan; Lee, Tzer-Min; Liao, Tze-Yuan; Lin, Huan-Chang; Chuang, Cheng-Hsin

    2017-03-01

    Fluorapatite (FA) has better chemical and thermal stability than hydroxyapatite (HA), and has thus attracted significant interest for biomaterial applications in recent years. In this study, porous bioceramic layers were prepared on pure titanium surfaces using a micro-arc oxidation (MAO) technique with an applied voltage of 450 V and an oxidation time of 5 min. The MAO process was performed using three different electrolyte solutions containing calcium fluoride (CaF2), calcium acetate monohydrate (Ca(CH3COO)2·H2O), and sodium phosphate monobasic dihydrate (NaH2PO4·2H2O) mixed in ratios of 0:2:1, 1:1:1, and 2:0:1, respectively. The surface morphology, composition, micro-hardness, porosity, and biological properties of the various MAO coatings were examined and compared. The results showed that as the CaF2/Ca(CH3COO)2·H2O ratio increased, the elemental composition of the MAO coating transformed from HA, A-TiO2 (Anatase) and R-TiO2 (Rutile); to A-TiO2, R-TiO2, and a small amount of HA; and finally A-TiO2, R-TiO2, CaF2, TiP2O5, and FA. The change in elemental composition was accompanied by a higher micro-hardness and a lower porosity. The coatings exhibited a similar in vitro bioactivity performance during immersion in simulated body fluid for 7-28 days. Furthermore, for in initial in vitro biocompatibility tests performed for 24 h using Dulbecco's Modified Eagle Medium (DMEM) supplement containing 10%Fetal bovine serum, the attachment and spreading of osteoblast-like osteosarcoma MG63 cells were found to increase slightly with an increasing CaF2/Ca(CH3COO)2·H2O ratio. In general, the results presented in this study show that all three MAO coatings possess a certain degree of in vitro bioactivity and biocompatibility.

  4. Interface structure between epitaxial NiSi2 and Si

    Institute of Scientific and Technical Information of China (English)

    Wei-Long Liu; Wen-Jauh Chen; Ting-Kan Tsai; Hsun-Heng Tsai; Shu-Huei Hsieh

    2006-01-01

    The interface structure between the Si and NiSi2 epitaxially grown on the ((-1)12) Si substrate was studied using high resolution transmission electron microscopy and computer image simulation. The results showed that the interface between Si and NiSi2 epitaxially grown on the ((-1)12) Si substrate has six different types: type A NiSi2 ((-1)11 )/( (-1)11 ) Si, type A NiSi2 (001)/(001) Si, type B NiSi2 (1(-1)(-1))/(1(-1)1) Si, type B NiSi2 ((-1)12)/(1(-1)2) Si, type B NiSi2 (2(-2)1)/(001) Si, and type B NiSi2 (1(-1)(4))/( 1(-1)0 ) Si. And there are one or more different atomic structures for one type of interface.

  5. 射频 Si/SiGe/Si HBT的研究%Studies on RF Si/SiGe/Si HBT

    Institute of Scientific and Technical Information of China (English)

    廖小平; 殷刚毅

    2003-01-01

    Si/SiGe/Si HBT与Si工艺兼容的研究基础上,对射频Si/SiGe/Si HBT的射频特性和制备工艺进行了研究,分析了与器件结构有关的关键参数寄生电容和寄生电阻与Si/SiGe/Si HBT的特征频率fT和最高振荡频率fmax的关系,成功地制备了fT为2.5 GHz、fmax为2.3 GHz的射频Si/SiGe/Si HBT,为具有更好的射频性能的Si/SiGe/Si HBT的研究建立了基础.

  6. Degradation behaviour of a new bioceramic: Ca2P2O7 with addition of Na4P2O7.10H2O.

    Science.gov (United States)

    Lin, F H; Liao, C J; Chen, K S; Sun, J S; Liu, H C

    1997-07-01

    A newly produced bioceramic, beta-Ca2P2O7 with addition of Na4P2O7.10H2O (SDCP), has been implanted into the femoral condyle of rabbits. Within 6 weeks after implantation, most of the bioceramic is replaced by new woven bone. On the contrary, block from hydroxyapatite (HA) and beta-tricalcium phosphate (beta-TCP), which are osteoconductible, do not resorb within a short period of time. We believe that the biodegradable behaviour of SDCP may occur in two steps. The first and most important step is the digestion of particles and migration of the particles by phagocytosis. The object of this study is to examine the change in morphologies, chemical compositions and crystal structure of SDCP after soaking in distilled water for a certain period of time. The SDCP ceramic was also co-cultured with leucocytes to observe how the SDCP particles were digested by the leucocytes, so that the mechanism of biodegradable behaviour of SDCP ceramic in vivo might be clarified. Four types of sintered calcium phosphate ceramics were tested in the experiment: SDCP, pure beta-Ca2P2O7 (DCP), HA and beta-TCP. They wee soaked in distilled water at 37 degrees C for up to 30 days. The microstructure and morphology of crystals deposited on the surface were observed using scanning electron microscopy. Sodium, calcium and phosphorus ion contents in the supernatant solution were detected by atomic absorption analysis and ion coupled plasma. In summary, HA and DCP showed no significant evidence of dissolution in distilled water. In static distilled water, calcium ions may be released from beta-TCP into solution during the initial 7 days and then converted into HA by reprecipitation. The results showed that the SDCP was firstly dissolved into small grains or fragments by the solution. The small fragments should be so small as to be digested by the phagocytes in a physiological environment.

  7. Privacy and Yin Si

    Institute of Scientific and Technical Information of China (English)

    胡迪

    2007-01-01

    <正>“Privacy” is translated as yin si in Chinese.Traditionally,in the Chinese mind,yin si is associated with something that is closed or unfair.If someone is said to have yin si,meddlers(好事者) will be attracted to pry(打探) into his or her affairs.So people always state that they don’t have yin si.

  8. Electroluminescence of Si Nanocrystal-Doped SiO2

    Institute of Scientific and Technical Information of China (English)

    CHEN Dan; XIE Zhi-Qiang; WU Qian; ZHAO You-Yuan; LU Ming

    2007-01-01

    @@ We perform a comparative study on the electroluminescence (EL) and photoluminescence (PL) of Si nanocrystaldoped SiO2 (nc-Si:SiO2) and SiO2, and clarify whether the contribution from Si nanocrystals in the EL of nc-Si:SiO2 truly exists. The results unambiguously indicate the presence of EL of Si nanocrystals. The difference of peak positions between the EL and PL spectra are discussed. It is found that the normal method of passivation to enhance the PL of Si nanocrystals is not equally effective for the EL, hence new methods need to be explored to promote the EL of Si nanocrystals.

  9. Si/SiO2和Si/SiNx/SiO2超晶格的能带结构%Band structure of Si/SiO2 and Si/SiNx/SiO2 superlattices

    Institute of Scientific and Technical Information of China (English)

    魏屹; 董成军; 徐明

    2010-01-01

    利用Kronig-Penney模型从理论上计算了Si/SiO2和Si/Si/SiNx/SiO2多层膜结构中量子阱的能带结构,进一步分析了各亚层薄膜厚度对能带结构和有效质量的影响.结果发现,适当减少亚层的厚度都能使得纳米Si薄膜的带隙发生明显宽化.在Si/SiO2超晶格中,Si量子阱层带隙能量随着Si层厚度的变化符合EPLL(eV)=1.6+0.7/d2关系,与我们的计算结果十分吻合.在Si/SiNdSiO2超晶格系统中,可以通过控制各亚层厚度,尤其是Si和SiNx层厚度,均能够有效地控制发光.

  10. Aperiodic SiSn/Si multilayers for thermoelectric applications

    Science.gov (United States)

    Tonkikh, A. A.; Zakharov, N. D.; Eisenschmidt, C.; Leipner, H. S.; Werner, P.

    2014-04-01

    We report on novel defect-free SiSn/Si heterostructures grown pseudomorphically on Si(001) substrates using temperature-modulated molecular beam epitaxy. This approach results in a sustainable epitaxial growth for SiSn/Si multilayers. Transmission electron microscopy and electron diffraction manifest that SiSn layers possess a diamond lattice structure. X-ray diffraction reveals up to 9.5 at% Sn in the crystal lattice of SiSn layers.

  11. The experimental study on the magnetic bioceramic implant body cage%磁性生物陶瓷椎体间融合器的研究

    Institute of Scientific and Technical Information of China (English)

    娄朝晖; 陈安民; 李峰; 郭风劲; 李建军; 孙淑珍

    2008-01-01

    目的 检测由磁性生物陶瓷制作椎体间融合器生物愈合的可行性与稳定性.方法 应用磁性生物陶瓷制作椎体间融合器后,选健康2~4岁山羊9只,平均体重27.8kg,经氯胺酮诱导,气管插管,安氟醚吸入麻醉后,取右下腹腹膜外斜切口,暴露L3与L4椎间隙后,保留前纵韧带,从椎间隙外侧切开纤维环,摘除髓核后,牵引及撑开椎间隙,刮除软骨终板,凿去大部分椎骨表面皮质骨,植入"楔形"磁性生物陶瓷椎体间融合器.结果 9只山羊均成活,术后约8h即可恢复站立,行走;24h后恢复正常行走,进食,但是活动较少,大多数时间处于卧位,休息;3周后情况明显好转,活动恢复至正常.术后6个月,腹部彩色B超检查未见血拴形成,腹部大血管血供正常.定期X线检查,肉眼大体标本观察,光境观察,扫描电镜(SEM)观察,材料与骨实现牢固的"生物愈合".结论 采用磁性生物陶瓷制作椎体间融合器植入体内是可行的.%Objective To study the effect and stability of the magnetic bioceramic implant body cage in sheep.Methods After the L4/5 intervertebral disc of sheep was removed and replaced with the magnetic bioceramic implant body cage,the recovery of the 9 sheep was observed.The animals were killed at intervals from 1st,3nd and 5th month after operation,and the interface between the prosthesis and bone was examined by naked eye inspection,roentgenography,light and scanning electron microphotography.Results The function of the sheep was recovered rapidly,and bone bonding with the prosthesis was found,but the activity of the sheep could resume normally 3 weeks after the operation.Conclusion The replacement with the magnetic bioceramic implant body cage after removal of the intervertebral disc is effective and stable,and the biological fixation could be achieved with the bone ingrowth.

  12. Mussel-inspired bioceramics with self-assembled Ca-P/polydopamine composite nanolayer: preparation, formation mechanism, improved cellular bioactivity and osteogenic differentiation of bone marrow stromal cells.

    Science.gov (United States)

    Wu, Chengtie; Han, Pingping; Liu, Xiaoguo; Xu, Mengchi; Tian, Tian; Chang, Jiang; Xiao, Yin

    2014-01-01

    The nanostructured surface of biomaterials plays an important role in improving their in vitro cellular bioactivity as well as stimulating in vivo tissue regeneration. Inspired by the mussel's adhesive versatility, which is thought to be due to the plaque-substrate interface being rich in 3,4-dihydroxy-l-phenylalamine (DOPA) and lysine amino acids, in this study we developed a self-assembly method to prepare a uniform calcium phosphate (Ca-P)/polydopamine composite nanolayer on the surface of β-tricalcium phosphate (β-TCP) bioceramics by soaking β-TCP bioceramics in Tris-dopamine solution. It was found that the addition of dopamine, reaction temperature and reaction time are three key factors inducing the formation of a uniform Ca-P/polydopamine composite nanolayer. The formation mechanism of a Ca-P/polydopamine composite nanolayer involved two important steps: (i) the addition of dopamine to Tris-HCl solution decreases the pH value and accelerates Ca and P ionic dissolution from the crystal boundaries of β-TCP ceramics; (ii) dopamine is polymerized to form self-assembled polydopamine film and, at the same time, nanosized Ca-P particles are mineralized with the assistance of polydopamine, in which the formation of polydopamine occurs simultaneously with Ca-P mineralization (formation of nanosized microparticles composed of calcium phosphate-based materials), and finally a self-assembled Ca-P/polydopamine composite nanolayer forms on the surface of the β-TCP ceramics. Furthermore, the formed self-assembled Ca-P/polydopamine composite nanolayer significantly enhances the surface roughness and hydrophilicity of β-TCP ceramics, and stimulates the attachment, proliferation, alkaline phosphate (ALP) activity and bone-related gene expression (ALP, OCN, COL1 and Runx2) of human bone marrow stromal cells. Our results suggest that the preparation of self-assembled Ca-P/polydopamine composite nanolayers is a viable method to modify the surface of biomaterials by

  13. Prose Writer Si Yu

    Institute of Scientific and Technical Information of China (English)

    1996-01-01

    SI Yu, pen name of Zhan Shaojuan, is well known through her prose works. During the recent more than ten years, Chinese prose writing has developed rapidly, from its previous level to the present flourishing conditions. Si Yu is a distinguished woman writer, whose creative prose alternately displays either

  14. In vitro remineralization of acid-etched human enamel with Ca 3SiO 5

    Science.gov (United States)

    Dong, Zhihong; Chang, Jiang; Deng, Yan; Joiner, Andrew

    2010-02-01

    Bioactive and inductive silicate-based bioceramics play an important role in hard tissue prosthetics such as bone and teeth. In the present study, a model was established to study the acid-etched enamel remineralization with tricalcium silicate (Ca 3SiO 5, C 3S) paste in vitro. After soaking in simulated oral fluid (SOF), Ca-P precipitation layer was formed on the enamel surface, with the prolonged soaking time, apatite layer turned into density and uniformity and thickness increasingly from 250 to 350 nm for 1 day to 1.7-1.9 μm for 7 days. Structure of apatite crystals was similar to that of hydroxyapatite (HAp). At the same time, surface smoothness of the remineralized layer is favorable for the oral hygiene. These results suggested that C 3S treated the acid-etched enamel can induce apatite formation, indicating the biomimic mineralization ability, and C 3S could be used as an agent of inductive biomineralization for the enamel prosthesis and protection.

  15. Comparative study on the biodegradation and biocompatibility of silicate bioceramic coatings on biodegradable magnesium alloy as biodegradable biomaterial

    Science.gov (United States)

    Razavi, M.; Fathi, M. H.; Savabi, O.; Razavi, S. M.; Hashemibeni, B.; Yazdimamaghani, M.; Vashaee, D.; Tayebi, L.

    2014-03-01

    Many clinical cases as well as in vivo and in vitro assessments have demonstrated that magnesium alloys possess good biocompatibility. Unfortunately, magnesium and its alloys degrade too quickly in physiological media. In order to improve the biodegradation resistance and biocompatibility of a biodegradable magnesium alloy, we have prepared three types of coating include diopside (CaMgSi2O6), akermanite (Ca2MgSi2O6) and bredigite (Ca7MgSi4O16) coating on AZ91 magnesium alloy through a micro-arc oxidation (MAO) and electrophoretic deposition (EPD) method. In this research, the biodegradation and biocompatibility behavior of samples were evaluated in vitro and in vivo. The in vitro analysis was performed by cytocompatibility and MTT-assay and the in vivo test was conducted on the implantation of samples in the greater trochanter of adult rabbits. The results showed that diopside coating has the best bone regeneration and bredigite has the best biodegradation resistance compared to others.

  16. Electroluminescence from Si/SiO2 films deposited on p-Si substrates

    Institute of Scientific and Technical Information of China (English)

    马书懿; 萧勇; 陈辉

    2002-01-01

    The structure of Au/Si/SiO2/p-Si has been fabricated using the magnetron sputtering technique. It has a verygood rectifying behaviour. Visible electroluminescence (EL) has been observed from the Au/Si/SiO2/p-Si structureat a forward bias of 5V or larger. A broad band with one peak around 650-660 nm appears in all the EL spectra ofthe structure. The effects of the thickness of the Si layer in the Si/SiO2 films and of the input electrical power on ELspectra are studied systematically.

  17. Influence of Si on Interfacial Combination of SiCp/Al-Mg-Si Composite

    Institute of Scientific and Technical Information of China (English)

    Han Jianmin; Li Ronghua; Li Mingwei; Cui Shihai; Li Weijing; Wang Jinhua

    2004-01-01

    The scanning electron microscopy (SEM) analysis results of Si distribution in the interface between SiC reinforcements and aluminum matrix of a stir casting SiCp/Al-Mg-Si composite were presented. Results show that there is Si precipitation deposit on the interface of the composite and Si connects with SiC reinforcements in one side and connects with aluminum matrix in the other side. Si phase plays as a connecting bridge, which contributes to the interfacial combination of SiCp/Al composite.

  18. Effect of metal-ion-to-fuel ratio on the phase formation of bioceramic phosphates synthesized by self-propagating combustion

    Directory of Open Access Journals (Sweden)

    Swamiappan Sasikumar and Rajagopalan Vijayaraghavan

    2008-01-01

    Full Text Available Synthetic calcium hydroxyapatite (HAP, Ca10 (PO46 (OH2 is a well-known bioceramic material used in orthopedic and dental applications because of its excellent biocompatibility and bone-bonding ability due to its structural and compositional similarity to human bone. Here we report, for the first time, the synthesis of HAP by combustion employing tartaric acid as a fuel. Calcium nitrate is used as the source of calcium and diammonium hydrogen phosphate serves as the source of phosphate ions. Reaction processing parameters such as the pH, fuel-oxidant ratio and autoignition temperature are controlled and monitored. The products were characterized by powder x-ray diffraction, which revealed the formation of a hexagonal hydroxyapatite phase. Fourier transform infrared spectroscopy (FT-IR spectra showed that the substitution of a carbonate ion occurs at the phosphate site. The morphology of the particles was imaged by scanning electron microscopy, which also revealed that the particles are of submicron size. Thermal analysis showed that the phase formation takes place at the time of combustion. Surface area and porosity analysis showed that the surface area is high and that the pores are of nanometer size. The mean grain size of the HAP powder, determined by the Debye–Scherrer formula, is in the range 20–30 nm. Chemical analyses to determine the Ca : P atomic ratio in synthesized ceramics were performed, and it was found to be 1 : 1.66.

  19. Influence of saline solution on hydration behavior of β-dicalcium silicate in comparison with biphasic calcium phosphate/hydroxyapatite bio-ceramics.

    Science.gov (United States)

    Radwan, M M; Abd El-Hamid, H K; Mohamed, A F

    2015-12-01

    The influence of using saline solution as mixing and curing liquid on some characteristics of β-dicalcium silicate (β-C2S) and biphasic compound tri-calcium phosphate/hydroxyapatite (TCP/HAp) bio-ceramics was investigated. β-C2S (27-30 nm) was prepared by solid state reaction at 1450°C, while biphasic compound TCP/HAp (7-15 nm) was synthesized from an aqueous solution of Ca(NO3)2·4H2O and (NH4)2HPO4·12H2O by chemical precipitation method. Setting times, compressive strength, pH values, X-ray diffraction analysis, infrared spectroscopy, scanning electron microscopy (SEM) were investigated. The evaluation of cytotoxicity of both calcium silicate and biphasic compounds to human gingival fibroblasts was carried out. The use of saline solution as mixing and immersing liquid shortened the setting time for the two bio-cements. TCP/HAp did not show any mechanical strength but β-C2S showed good strength values. Both synthesized compounds showed a moderate cytotoxicity and both materials were effective in a no significant way.

  20. Biphasic calcium phosphates bioceramics (HA/TCP): Concept, physicochemical properties and the impact of standardization of study protocols in biomaterials research.

    Science.gov (United States)

    Ebrahimi, Mehdi; Botelho, Michael G; Dorozhkin, Sergey V

    2017-02-01

    Biphasic calcium phosphates (BCP) bioceramics have become the materials of choice in various orthopedic and maxillofacial bone repair procedures. One of their main advantages is their biodegradation rate that can be modified by changing the proportional ratio of the composition phases. For enhanced bone tissue regeneration, the bioactivity of BCP should be increased by optimizing their physicochemical properties. To date, the ideal physicochemical properties of BCP for bone applications have not been defined. This is mostly related to lack of standard study protocols in biomaterial science especially with regards to their characterizations and clinical applications. In this paper we provided a review on BCP and their physicochemical properties relevant to clinical applications. In addition, we summarized the available literature on their use in animal models and evaluated the influences of different composition ratios on bone healing. Controversies in literature with regards to ideal composition ratio of BCP have also been discussed in detail. We illustrated the discrepancies in study protocols among researchers in animal studies and emphasized the need to develop and follow a set of generally accepted standardized guidelines. Finally; we provided general recommendations for future pre-clinical studies that allow better standardization of study protocols. This will allow better comparison and contrast of newly developed bone substitute biomaterials that help further progress in the field of biomaterial science.

  1. Zn改性纳米ZSM-5分子筛的制备及其催化己烯-1芳构化反应性能%Preparation of Zn-modified nano-ZSM-5 zeolite and its catalytic performance in aromatization of 1-hexene

    Institute of Scientific and Technical Information of China (English)

    王高亮; 吴伟; 昝望; 白雪峰; 王文静; 戚鑫; O.V.KIKHTYANIN

    2015-01-01

    研究以浸渍法和同晶置换法引入Zn对纳米ZSM-5分子筛催化己烯-1芳构化反应性能的促进作用.采用无模板剂的晶种引导法合成具有纳米尺度的ZSM-5分子筛.分别以传统浸渍法和同晶置换法制备Zn改性的纳米ZSM-5分子筛催化剂xZn/HNZ5和yZn/Al-HNZ5.采用XRD、XRF、N2物理吸附、SEM、NH3-TPD和Py-IR等分析手段对所制备样品的结构、化学组成以及酸性进行表征,并在480 °C和质量空速为2.0 h-1的条件下对其催化己烯-1芳构化性能进行考察.与xZn/HNZ5相比,yZn/Al-HNZ5表现出更小的粒径尺寸和更高的Zn物种分散度,使其具有更大的晶间介孔和更均匀的酸中心分布.催化性能评价结果表明,Zn 同晶置换改性的纳米 ZSM-5 分子筛具有更好的Br-nsted和 Lewis酸中心协同作用,能够显著地提高纳米ZSM-5分子筛的催化己烯-1芳构化反应收率和稳定性.%The promoting effect of introducing Zn into nano-ZSM-5 zeolites by conventional impregnation method and isomorphous substitution on the performance of 1-hexene aromatization was investigated. The nano-ZSM-5 zeolite was synthesized by a seed-induced method without organic templates. The Zn-modified nano-ZSM-5 zeolite catalysts,xZn/HNZ5 andyZn/Al-HNZ5, were prepared by the conventional impregnation method and isomorphous substitution, respectively. The structure, chemical composition and acidity of the catalysts were characterized by XRD, XRF, N2 adsorption, SEM, NH3-TPD and Py-IR, while the catalytic properties were evaluated at 480 °C and a weight hourly space velocity (WHSV) of 2.0 h-1 in the aromatization procedure of 1-hexene. Compared withxZn/HNZ5,yZn/Al-HNZ5 exhibited smaller particles and higher dispersion of Zn species, which led to greater intergranular mesopore and homogeneous acidity distribution. Experimental results indicated that the synergy effect between the Br-nsted and Lewis acid sites of the isomorphously substituted nano-ZSM-5 zeolites could

  2. Bioactivity analysis of the Ta (V) doped SiO2-CaO-Na2O-P2O5 ceramics prepared by solid state sintering method

    Institute of Scientific and Technical Information of China (English)

    Rehana Zia; Madeeha Riaz; Nida ul nasir; Farhat Saleemi; Zora Kayani; Safia Anjum; Farooq Bashir; Tousif Hussain

    2016-01-01

    The main objective of the study was to control the degradation rate of material at a higher degradation rate improving the chemical stability of the material. Ta is known to have good chemical resistance, biocompatibility and show no adverse biological response. In the present study, SiO2–Na2O–CaO–P2O5 bioceramics with different Ta2O5 contents was prepared by solid state sintering method at 1000 °C. The as-sintered ceramics were subjected to immersion studies in stimulated body fluid (SBF) for 21 days under static condition and characterized by XRD, FTIR, SEM, and AAS. The findings of the research indicate that the addition of Ta2O5 controlled degradability, and all samples showed sufficient bioactivity.

  3. 生物活性稀土梯度涂层在碱液环境中的电极化后处理%Electric polarized post treatment of rare earth active bioceramic gradient coating in alkaline solution

    Institute of Scientific and Technical Information of China (English)

    汪震; 刘其斌; 肖明; 杨邦成

    2011-01-01

    To improve the quality of rare earth active bioceramic gradient coatings,a method of electric polarized treatment(PAS) was used to post-process the gradient coatings fabricated by wide band laser cladding in alkali liquid.The phases and corrosion resistance of the bioceramic coatings were analyzed by XRD and an electrochemical analyzer.The bioceramic coatings were immersed in simulated body fluid(SBF) to examine its bioactivity and its electrical charge.The experimental results indicate that PAS treatment not only improves the crystallinity of the coatings,but also is favourable to transform additional phases into hydroxyapatite.PAS treatment exhibits a little effect on corrosion resistance of the bioceramic coatings.Compared with as-received coatings,the coatings treated by PAS are of better bioactivity and more negative charge.%为了改善活性生物稀土梯度涂层的质量,在碱液环境中采用电极化处理法(PAS)对宽带激光熔覆生物活性稀土梯度涂层进行后处理。利用XRD和电化学分析仪对涂层的相组成和耐腐蚀性进行了研究,通过模拟体液浸泡试验考察了生物陶瓷涂层的生物活性和涂层表面的电荷分布情况。结果表明,碱液环境中电极化处理法(PAS)能够提高涂层的结晶度,使涂层中的非晶相、杂相向羟基磷灰石转化。PAS对涂层的耐腐蚀性影响不大。与未处理涂层相比,PAS处理后的涂层生物活性更好,且涂层表面产生了更多的负电荷。

  4. Introduction of atomic H into Si3N4/SiO2/Si stacks

    Institute of Scientific and Technical Information of China (English)

    JIN Hao; WEBER K.J.; LI Weitang; BLAKERS A.W.

    2006-01-01

    Atomic H generated by a plasma NH3 source at 400 ℃ was demonstrated to passivate dehydrogenated Si3N4/SiO2/Si stacks effectively by bonding with defectsin the Si3N4 film and at the Si-SiO2 interface. A subsequent anneal in N2 after atomic H reintroduction was demonstrated to further improve passivation of the Si-SiO2 interface. Isothermal and isochronal anneals in N2 were carried out in order to determine the optimized annealing conditions.

  5. Photoelectric properties of n-SiC/n-Si heterojunctions

    Directory of Open Access Journals (Sweden)

    Semenov A. V.

    2012-10-01

    Full Text Available Photovoltaic effect in isotype heterotructure formed by nanocrystalline silicon carbide films on single crystal n-Si substrates (n-SiC/n-Si heterojunction was studied. The films were produced by direct ionic deposition method. The model that takes into account the quantum wells and potential barriers caused by band offsets was proposed to explain the current-voltage characteristics and photovoltaic properties of the heterostructure n-SiC/n-Si.

  6. Electronic Structure of Si1-xIVx/Si Superlattices on Si(001)

    Institute of Scientific and Technical Information of China (English)

    CHEN Jie; L(U) Tie-Yu; HUANG Mei-Chun

    2007-01-01

    We have preformed systematical ab initio studies of the structural and electronic properties of short-period Si1-xIVx/Si (x = 0.125, 0.25, 0.5,IV=Ge, Sn) superlattices (SLs) grown along the [001] direction on bulk Si. The present calculations reveal that the Si0.875 Ge0.125/Si, Si0.75 Ge0.25/Si and Si0.875Sn0.125/Si axe the Γ-point direct bandgap semiconductors. The technological importance lies in the expectation that the direct gap Si1-xIVx/Si SLs may be used as components in integrated optoelectronic devices, in conjunction with the already well-established and highly advanced silicon technology.

  7. Interfacial reaction of eutectic AuSi solder with Si (100) and Si (111) surfaces

    Science.gov (United States)

    Jang, Jin-Wook; Hayes, Scott; Lin, Jong-Kai; Frear, Darrel R.

    2004-06-01

    The dissolution behavior of Si (100) and (111) dies by eutectic AuSi solder was investigated. On the Si (100) surface, the dissolution primarily occurred by the formation of craters resulting in a rough surface. The dissolution of the Si (111) resulted in a relatively smooth surface. The morphology of the Si (100) surface during a AuSi soldering reaction exhibited more time-dependent behavior and the etching craters on a Si (100) surface grew larger with time whereas Si (111) did not significantly change. This difference was ascribed to the surface energy differences between Si (111) and (100) surfaces that resulted in the two- and three-dimensional dissolution behaviors, respectively. This difference plays an important role in the formation of voids during the AuSi die bonding. The etching craters on Si (100) act as a AuSi solder sink and the regions surrounded by etch pits tend to become voids. For Si (111), flat surfaces were observed in the voided regions. Cross section analysis showed that no solder reaction occurred in the voided region of the Si (111) surface. This suggests the possibility of the formation of a thin inert layer in a potentially voided region prior to assembly. To achieve void-free die bonding, different parameters must be adjusted to the Si (100) and Si (111) surfaces with the AuSi alloy.

  8. Correlation between Light Emissions from Amorphous-Si:H/SiO2 and nc-Si/SiO2 Multilayers

    Institute of Scientific and Technical Information of China (English)

    MA Zhong-Yuan; HUANG Xin-Fan; CHEN Kun-Ji; FENG Duan; HAN Pei-Gao; LI Wei; CHEN De-Yuan; WEI De-Yuan; QIAN Bo; LI Wei; XU Jun; XU Ling

    2007-01-01

    We investigate the properties of light emission from amorphous-Si:H/SiO2 and nc-Si/SiO2 multilayers (MLs). The size dependence of light emission is well exhibited when the a-Si:H sublayer thickness is thinner than 4nm and the interface states are well passivated by hydrogen. For the nc-Si/SiO2 MLs, the oxygen modified interface states and nanocrystalline silicon play a predominant role in the properties of light emission. It is found that the light emission from nc-Si/SiO2 is in agreement with the model of interface state combining with quantum confinement when the size of nc-Si is smaller than 4 nm. The role of hydrogen and oxygen is discussed in detail.

  9. a-Si/c-Si heterojunction solar cells on SiSiC ceramic substrates

    Institute of Scientific and Technical Information of China (English)

    LI Xudong; XU Ying; CHE Xiaoqi

    2006-01-01

    Silicon thin-film solar cells are considered to be one of the most promising cells in the future for their potential advantages, such as low cost, high efficiency, great stability, simple processing, and none-pollution. In this paper, latest progress on poly-crystalline silicon solar cells on ceramic substrates achieved by our group was reported. Rapid thermal chemical vapor deposition (RTCVD) was used to deposited poly-crystalline silicon thin films, and the grains of as-grown film were enlarged by Zone-melting Recrystallization (ZMR). As a great changein cell's structure, traditional diffused pn homojunction was replaced by a-Si/c-Si heterojunction, which lead is to distinct improvement in cell's efficiency.A conversion efficiency of 3.42% has been achieved on 1cm2 a-Si/c-Si heterojunction solar cell ( Isc =16.93 mA, Voc =310.9 mV, FF =06493, AM =1.5 G,24 ℃), while the cell with diffused homojunction only gotan efficiency of 0.6%. It indicates that a-Si emitter formed at low temperature might be more suitable for thin film cell on ceramics.

  10. A comparative study of electroluminescence from Ge/SiO2 and Si/SiO2 films

    Institute of Scientific and Technical Information of China (English)

    Ma Shu-Yi; Chen Hui; Xiao Yong; Ma Zi-Jun; Sun Ai-Min

    2004-01-01

    Ge/SiO2 and Si/SiO2 films were deposited using the two-target alternation magnetron sputtering technique. The Au/Ge/SiO2/p-Si and Au/Si/SiO2/p-Si structures were fabricated and their electroluminescence (EL) characteristics were comparatively studied. Both Au/Ge/SiO2/p-Si and Au/Si/SiO2/p-Si structures have rectifying property. All the EL spectra from the two types of the structure have peak positions around 650-660 nm. The EL mechanisms of the structures are discussed.

  11. Evaluation of a Novel HA/ZrO2-Based Porous Bioceramic Artificial Vertebral Body Combined with a rhBMP-2/Chitosan Slow-Release Hydrogel

    Science.gov (United States)

    Shi, Yihui; Quan, Renfu; Xie, Shangju; Li, Qiang; Cao, Guoping; Zhuang, Wei; Zhang, Liang; Shao, Rongxue; Yang, Disheng

    2016-01-01

    A new HA/ZrO2-based porous bioceramic artificial vertebral body (AVB), carried a recombinant human bone morphogenetic protein-2 (rhBMP-2)/chitosan slow-release hydrogel was prepared to repair vertebral bone defect in beagles. An ionic cross-linking was used to prepare the chitosan hydrogel (CS gel) as the rhBMP-2 slow-release carrier. The vertebral body defects were implanted with the rhBMP-2-loaded AVB in group A, or a non-drug-loaded AVB in group B, or autologous iliac in group C. The encapsulation rate of rhBMP-2 in rhBMP-2-loaded CS gel was 91.88±1.53%, with a drug load of 39.84±2.34 ng/mg. At 6, 12, 24 weeks postoperatively, radiography showed that the bone calluses gradually increased with time in group A, where the artificial vertebral body had completely fused with host-bone at 24 weeks after surgery. In group C, an apparent bone remodeling was occurred in the early stages, and the graft-bone and host-bone had also fused completely at 24 weeks postoperatively. In group B, fusion occurred less than in groups A and C. At 24 weeks after surgery, micro-computed tomography (Micro-CT) revealed that the volume of newly-formed bone in group A was significantly more than in group B (pbioceramic AVB carried the rhBMP-2-loaded CS gel can promote the repair of bony defect, and induce bone tissue to grow into the pores, which may replace iliac bone grafts as commonly applied in clinical practice. PMID:27400197

  12. 生物陶瓷表面蛋白吸附的研究进展%Research progress of protein adsorption on surface of bioceramics

    Institute of Scientific and Technical Information of China (English)

    王传勇

    2012-01-01

    Bioactive ceramics have been widely used in replacing defected hard tissues caused by trauma or disease. When biomaterials are placed in bio-enviroments, various protein molecules will immediately accumulate on material surfaces forming a bioactive layer. Moreover, this protein layer plays an important role in determining the biocompatibility of materials. So this paper briefly reviews the protein adsorption on bioceramics surfaces, including the type of proteins absorbed, methods being used, factors effecting adsorption capacity and methods improving it, providing reference for the surface biological modification of bioactive ceramic materials.%近年来,生物陶瓷材料在替代因外伤或疾病而导致缺损的硬组织方面已获得广泛的应用,当材料被植入生物体内后,其表面立即会发生多种蛋白质分子的堆积,这一蛋白质层对于改变材料的表面性质起着重要的作用.因此,对生物材料表面蛋白吸附的考察已经成为评价材料生物相容性和生物活性的重要内容.本文就生物陶瓷表面蛋白吸附的主要种类、研究方法、影响因素及其改进研究等相关内容作一综述,以期为生物陶瓷表面生物学改性的研究提供基础理论参考.

  13. Frittage micro-ondes en cavité monomode de biocéramiques Microwaves sintering of bioceramics in a single mode cavity

    Directory of Open Access Journals (Sweden)

    Savary Etienne

    2013-11-01

    Full Text Available Le but premier de cette étude est de montrer la faisabilité du frittage direct en cavité micro-ondes monomode de deux biomatériaux céramiques : l'hydroxyapatite et le phosphate tri-calcique. Ainsi, cette étude montre que ce procédé a permis d'obtenir, en des temps très courts, inférieurs à 20 minutes, des échantillons denses présentant des microstructures fines. Les caractérisations mécaniques sur les échantillons frittés par micro-ondes ont révélé des valeurs de module d'élasticité et de dureté supérieures à celles généralement obtenues sur des échantillons frittés de manière conventionnelle. Ces résultats sont discutés en fonction de la microstructure obtenue et des différents paramètres expérimentaux : granulométrie des poudres, température de frittage, temps d'irradiation micro-ondes. The main purpose of this study consists in investigating the direct microwaves sintering in a single mode cavity of two bioceramics: hydroxyapatite and tri-calcium phosphate. Thus, dense samples presenting fine microstructures are successfully obtained in less than 20 minutes of irradiation. The resulting mechanical characterizations on microwaves sintered samples evidence higher Young's modulus and hardness values than those usually reported on conventionally sintered samples. Those results are discussed according to the microstructures observed and the experimental parameters such as powders granulometries, sintering temperatures, microwaves irradiation times.

  14. Influence of saline solution on hydration behavior of β-dicalcium silicate in comparison with biphasic calcium phosphate/hydroxyapatite bio-ceramics

    Energy Technology Data Exchange (ETDEWEB)

    Radwan, M.M., E-mail: mmahmoudradwan@yahoo.com [Ceramics Dept, National Research Centre, Cairo (Egypt); Abd El-Hamid, H.K. [Ceramics Dept, National Research Centre, Cairo (Egypt); Mohamed, A.F. [The Holding Company for Production of Vaccines, Sera and Drugs (EGYVAC) (Egypt)

    2015-12-01

    The influence of using saline solution as mixing and curing liquid on some characteristics of β-dicalcium silicate (β-C{sub 2}S) and biphasic compound tri-calcium phosphate/hydroxyapatite (TCP/HAp) bio-ceramics was investigated. β-C{sub 2}S (27–30 nm) was prepared by solid state reaction at 1450 °C, while biphasic compound TCP/HAp (7–15 nm) was synthesized from an aqueous solution of Ca(NO{sub 3}){sub 2}·4H{sub 2}O and (NH{sub 4}){sub 2}HPO{sub 4}·12H{sub 2}O by chemical precipitation method. Setting times, compressive strength, pH values, X-ray diffraction analysis, infrared spectroscopy, scanning electron microscopy (SEM) were investigated. The evaluation of cytotoxicity of both calcium silicate and biphasic compounds to human gingival fibroblasts was carried out. The use of saline solution as mixing and immersing liquid shortened the setting time for the two bio-cements. TCP/HAp did not show any mechanical strength but β-C{sub 2}S showed good strength values. Both synthesized compounds showed a moderate cytotoxicity and both materials were effective in a no significant way. - Highlights: • The dissolution and hydration of β-C{sub 2}S and TCP/HAp in distilled water and saline solution were studied. • TCP/HAp did not show mechanical strength, while β-C{sub 2}S showed good mechanical strength. • The use of saline solution did enhances the dissolution & hydration rate. • An increase in pH values was detected when using saline solution. • Both materials showed a moderate cytotoxicity in no significant way.

  15. Transport and electroluminescence mechanism in Au/(Si/SiO2)/P-Si film

    Institute of Scientific and Technical Information of China (English)

    ZHANG Kai-biao; MA Shu-yi; MA Zi-jun; CHEN Hai-xia

    2006-01-01

    The samples of Au/(Si/SiO2)/p-Si structure were fabricated by using the R.F magnetron sputtering technique.Its carrier transport and electroluminescence mechanism were studied from the I-V curves and EL spectra by using the Configuration Coordinate as a theoretical model.The result indicates that there are two defect centers in SiO2 films.The electron in Au and the hole in p-Si went into SiO2 film by the Fowler-Nordheim tunneling model at a high bias voltage and recombined through these defect centers in SiO2 film.

  16. Photoreflectance Spectroscopy for Study of Si/SiGe/Si Heterostructure

    Institute of Scientific and Technical Information of China (English)

    Liu Zhihong; Chen Changchun; Lin Huiwang; Xiong Xiaoyi; Dou Weizhi; Tsien Pei-Hsin

    2004-01-01

    UHVCVD-grown Si/Si1- xGex/Si heterostructure was investigated by Photoreflectance spectroscopy (PR). The principle of PR used in semiconductor film was thoroughly described. According to the E1 transition energy in the Si1- xGex alloy, the Ge content in SiGe film with constant composition can be accurately characterized. In this study, determine the composition uniformity of larger diameter SiGe epiwafer by PR mapping technique was determined. These results show PR is very promising for Si1- xGex epilayer characterization with constant Ge content and can provide film measurements for production-worthy line monitor.

  17. Features of Mg2Si Layer Growth in Si/Mg2Si Multilayers

    Directory of Open Access Journals (Sweden)

    L.E. Konotopskyi

    2016-06-01

    Full Text Available Features of magnesium siliced layer growth in Si/Mg2Si multilayers in initial state and after thermal annealing were studied by methods of transmission electron microscopy and X-Ray scattering. As-deposited magnesium silicide layers are amorphous with nanocrystal inclusions of metastable h-Mg2Si. Formation of Mg2Si in hexagonal modification occurs under the influence of stress produced by silicon layers. At T = 723 К Mg2Si layers finished crystallizes in hexagonal modification, with some coarsening of grains. That is accompanied with 7.3 % reduction in period of the Si/Mg2Si multilayer.

  18. The property of Si/SiGe/Si heterostructure during thermal budget characterized by HRXRD

    Institute of Scientific and Technical Information of China (English)

    CHEN Chang-Chun; LIU Zhi-Hong; HUANG Wen-Tao; DOU Wei-Zhi; ZHANG Wei; TSIEN Pei-Hsin; ZHU De-Zhang

    2003-01-01

    Si/SiGe/Si heterostructures grown by ultra-high-vacuum chemical vapor deposition (UHVCVD) werecharacterized by Rutherford backscattering/Channeling (RBS/C) together with high resolution X ray diffraction(HRXRD). High quality SiGe base layer was obtained. The Si/SiGe/Si heterostructures were subject to conventionalfurnace annealing and rapid thermal annealing with temperature between 750 ℃ and 910 ℃. Both strain and its re-laxation degree in SiGe layer are calculated by HRXRD combined with elastic theory, which are never reported inother literatures. The rapid thermal annealing at elevated temperature between 880 ℃ and 910 ℃ for very short timehad almost no influence on the strain in Si0.84Ge0. 16 epilayer. However, high temperature (900℃) furnace annealingfor 1h prompted the strain in Si0.84Ge0.16 layer to relax.

  19. Si/SiGe/Si HBT的直流特性和低频噪声%Si/SiGe/Si HBT's DC Characterization and Its Low-frequency Noise

    Institute of Scientific and Technical Information of China (English)

    廖小平; 张中平

    2003-01-01

    在对Si/SiGe/Si HBT及其Si兼容工艺的研究基础上,研制成功低噪声Si/SiGe/Si HBT,测试和分析了它的直流特性和低频噪声特性,为具有更好的低噪声性能的Si/SiGe/Si HBT的研究建立了基础.

  20. Effect of Si/Si1-yCy/Si Barriers on the Characteristics of Si1-xGex/Si Resonant Tunneling Structures

    Institute of Scientific and Technical Information of China (English)

    HAN Ping; CHENG Xue-Mei; Masao Sakuraba; YoungCheon Jeong; Takashi Matsuura; Junichi Murota

    2000-01-01

    P-type double barrier resonant tunneling diodes (RTD) with the single Si0.6Ge0.4 quantum well and double Si0.6 Ge0.4 spacer have been realized by using an ultra clean low-pressure chemical vapor deposition system. The effect of Si1-yCy layer on the characteristics of the devices was shown by comparing the current-voltage (Ⅰ-Ⅴ) characteristics of RTD's of the barriers of Si layers with that of Si/Si1-yCy/Si structures. The peak voltage was gradually increased and the resonant current decreased obviously with increasing C content in the Si/Si1-yCy/Si barriers. The origin of the phenomena above can be attributed to the C related deep acceptor levels in the Si/Si1-yCy/Si barriers. The possible mechanism for the observed Ⅰ-Ⅴcharacteristics was shown more clearly by increasing C content to 3% and changing the thicknesses of Si and Si1-yCy layers in the Si/Si1-yCy/Si barriers.

  1. Relaxed SiGe-on-insulator fabricated by dry oxidation of sandwiched Si/SiGe/Si structure

    Energy Technology Data Exchange (ETDEWEB)

    Di Zengfeng [Research Center of Semiconductor Functional Film Engineering Technology and State Key Laboratory of Functional Materials for Informatics, Shanghai Institute of Microsystem and Information Technology (SIMIT), Chinese Academy of Sciences (CAS), Shanghai 200050 (China); Department of Physics and Material Science, City University of Hong Kong, Tat Chee Avenue, Kowloon, Hong Kong (China); Zhang Miao [Research Center of Semiconductor Functional Film Engineering Technology and State Key Laboratory of Functional Materials for Informatics, Shanghai Institute of Microsystem and Information Technology (SIMIT), Chinese Academy of Sciences (CAS), Shanghai 200050 (China); Liu Weili [Research Center of Semiconductor Functional Film Engineering Technology and State Key Laboratory of Functional Materials for Informatics, Shanghai Institute of Microsystem and Information Technology (SIMIT), Chinese Academy of Sciences (CAS), Shanghai 200050 (China); Zhu Ming [Research Center of Semiconductor Functional Film Engineering Technology and State Key Laboratory of Functional Materials for Informatics, Shanghai Institute of Microsystem and Information Technology (SIMIT), Chinese Academy of Sciences (CAS), Shanghai 200050 (China); Department of Physics and Material Science, City University of Hong Kong, Tat Chee Avenue, Kowloon, Hong Kong (China); Lin Chenglu [Research Center of Semiconductor Functional Film Engineering Technology and State Key Laboratory of Functional Materials for Informatics, Shanghai Institute of Microsystem and Information Technology (SIMIT), Chinese Academy of Sciences (CAS), Shanghai 200050 (China); Chu, Paul K. [Department of Physics and Material Science, City University of Hong Kong, Tat Chee Avenue, Kowloon, Hong Kong (China)]. E-mail: paul.chu@cityu.edu.hk

    2005-12-05

    An improved technique is demonstrated to fabricate silicon-germanium on insulator (SGOI) starting with a sandwiched structure of Si/SiGe/Si. After oxidation of the sandwiched structure and successive annealing, a relaxed SiGe-on-insulator (SGOI) structure is produced. Our results indicate that the added Si cap layer is advantageous in suppressing Ge loss at the initial stage of SiGe oxidation and the subsequent annealing process homogenizes the Ge fraction. Raman measurements reveal that the strain in the SiGe layer is fully relaxed at high oxidation temperature ({approx}1150 deg. C) without generating any threading dislocations and crosshatch patterns, which generally exist in the relaxed SiGe layer on bulk Si substrate.

  2. Endotaxial Si nanolines in Si(001):H

    Science.gov (United States)

    Bianco, F.; Owen, J. H. G.; Köster, S. A.; Mazur, D.; Renner, Ch.; Bowler, D. R.

    2011-07-01

    We present a detailed study of the structural and electronic properties of a self-assembled silicon nanoline embedded in the H-terminated silicon (001) surface, known as the Haiku stripe. The nanoline is a perfectly straight and defect-free endotaxial structure of huge aspect ratio; it can grow micrometer long at a constant width of exactly four Si dimers (1.54 nm). Another remarkable property is its capacity to be exposed to air without suffering any degradation. The nanoline grows independently of any step edges at tunable densities from isolated nanolines to a dense array of nanolines. In addition to these unique structural characteristics, scanning tunneling microscopy and density functional theory reveal a one-dimensional state confined along the Haiku core. This nanoline is a promising candidate for the long-sought-after electronic solid-state one-dimensional model system to explore the fascinating quantum properties emerging in such reduced dimensionality.

  3. Annealing Behavior of Si1-xGex/Si Heterostructures

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    The behavior of Si1-xGex/Si heterostructures under different annealing conditions has been studied. It is found that while RTA treatment diminishes the point defects, it introduces the misfit dislocations into Si1-xGex layers at same time. Higher annealing temperature will result in the propagation of misfit dislocations and then the total destruction of the crystal quality.

  4. Si-to-Si wafer bonding using evaporated glass

    DEFF Research Database (Denmark)

    Reus, Roger De; Lindahl, M.

    1997-01-01

    Anodic bonding of Si to Si four inch wafers using evaporated glass was performed in air at temperatures ranging from 300°C to 450°C. Although annealing of Si/glass structures around 340°C for 15 minutes eliminates stress, the bonded wafer pairs exhibit compressive stress. Pull testing revealed...

  5. Si nanoparticle interfaces in Si/SiO solar cell materials

    DEFF Research Database (Denmark)

    Kilpeläinen, S.; Kujala, J.; Tuomisto, F.;

    2013-01-01

    Novel solar cell materials consisting of Si nanoparticles embedded in SiO2 layers have been studied using positron annihilation spectroscopy in Doppler broadening mode and photoluminescence. Two positron-trapping interface states are observed after high temperature annealing at 1100 °C. One...... of the states is attributed to the (SiO2/Si bulk) interface and the other to the interface between the Si nanoparticles and SiO2. A small reduction in positron trapping into these states is observed after annealing the samples in N2 atmosphere with 5% H2. Enhanced photoluminescence is also observed from...

  6. Resonant Tunnelling and Storage of Electrons in Si Nanocrystals within a-SiNx/nc-Si/a-SiNx Structures

    Institute of Scientific and Technical Information of China (English)

    WANG Xiang; HUANG Jian; ZHANG Xian-Gao; DING Hong-Lin; YU Lin-Wei; HUANG Xin-Fan; LI Wei; XU Jun; CHEN Kun-Ji

    2008-01-01

    @@ The a-SiNx/nanocrystalline silicon (nc-Si)/a-SiNx sandwiched structures with asymmetric double-barrier are fabricated in a plasma enhanced chemical vapour deposition (PECVD) system on p-type Si substrates. The nc-Si layer in thickness 5nm is fabricated from a hydrogen-diluted silane gas by the layer-by-layer deposition technique. The thicknesses of tunnel and control SiNx layers are 3nm and 20nm,respectively. Frequency-dependent capacitance spectroscopy is used to study the electron tunnelling and the storage in the sandwiched structures.Distinct frequency-dependent capacitance peaks due to electrons tunnelling into the nc-Si dots and capacitance-voltage (C- V) hysteresis characteristic due to electrons storage in the nc-Si dots are observed with the same sample.

  7. Helimagnetic order in bulk MnSi and CoSi/MnSi superlattices

    Science.gov (United States)

    Loh, G. C.; Khoo, K. H.; Gan, C. K.

    2017-01-01

    Skyrmions are nanoscopic whirls of spins that reside in chiral magnets. It is only fairly recent that a plethora of applications for these quasiparticles emerges, especially in data storage. On the other hand, spin spirals are the periodic analogs of skyrmions, and are equally imperative in the course of exploration to enhance our understanding of helimagnetism. In this study, a new infrastructure based on the B20 compound, MnSi is propounded as a hosting material for spin spirals; alternating thin layers of CoSi and MnSi in the superlattice form provides a facile way of varying the properties of the spin spirals across a continuum. Using first-principles calculations based on full-potential linearized augmented plane-wave (FLAPW)-based density functional theory (DFT), the spin order of bulk MnSi, MnSi film, and the CoSi/MnSi superlattice is investigated. Spin dispersion plots as a function of propagation vectors show that the spiral size changes in the presence of CoSi - we find that the size of the spiral is reduced in the superlattice with thin CoSi layers (CoSi:MnSi=1:1 thickness ratio), whilst at a larger CoSi:MnSi=2:1 thickness ratio, the material behaves as a ferromagnet. In a similar fashion, the spin moment and orbital occupancy depend significantly on the thickness of the CoSi layers. However, the exchange interaction between Mn atoms appears to be generally impervious to the presence of CoSi. Succinctly, the CoSi/MnSi superlattice could be an excellent functional material in data storage applications.

  8. Photoluminescence from SiO sub 2 /Si/SiO sub 2 structures

    CERN Document Server

    Photopoulos, P

    2003-01-01

    Si layers were developed on pre-oxidized Si wafers by decomposition of silane in a low pressure chemical vapour deposition reactor. By keeping the deposition time constant (2 min) three sets of samples were fabricated at deposition temperatures equal to 580, 610 and 625 deg C. The deposited Si layers were thinned by high temperature dry oxidation thus forming SiO sub 2 /Si/SiO sub 2 structures. Room temperature photoluminescence (PL) measurements showed that for those samples in which the thickness of the remaining Si layer was greater than approx 6 nm, the spectra exhibited a peak at approx 650 nm. Prolonged oxidations led to the formation of SiO sub 2 /nanocrystalline-Si/SiO sub 2 structures in which the thickness of the remaining nanocrystalline Si (nc-Si) layer was smaller than 3 nm. The PL spectra obtained from these structures were at least ten times stronger compared to the previous ones. The PL peak wavelength exhibited a weak dependence on the nc-Si layer thickness shifting from 800 to 720 nm for nc-...

  9. Strained Si/SiGe MOS transistor model

    Directory of Open Access Journals (Sweden)

    Tatjana Pešić-Brđanin

    2009-06-01

    Full Text Available In this paper we describe a new model of surfacechannel strained-Si/SiGe MOSFET based on the extension of non-quasi-static (NQS circuit model previously derived for bulk-Si devices. Basic equations of the NQS model have been modified to account for the new physical parameters of strained-Si and relaxed-SiGe layers. From the comparisons with measurements, it is shown that a modified NQS MOS including steady-state self heating can accurately predict DC characteristics of Strained Silicon MOSFETs.

  10. Quantum devices using SiGe/Si heterostructures

    Energy Technology Data Exchange (ETDEWEB)

    Karunasiri, R.P.G.; Wang, K.L. (Univ. of California, Los Angeles (United States))

    Strained-layer Si{sub 1-x}Ge{sub x}/Si heterostructures have created a great deal of interest due to the potential of integration with the conventional silicon very large scale integrated technology. With the current advances in silicon molecular beam epitaxy (Si-MBE) and other low-temperature epitaxial techniques, many Si{sub 1-x}Ge{sub x}/Si heterojunction devices have been realized. For example, among those realized are avalanche photodiodes, modulation-doped field-effect transistors, heterojunction bipolar transistors, and more recently, resonant tunneling structures, hot-carrier transistors, and quantum well metal-oxide-semiconductor field-effect transistors. In this paper several quantum size effects in strained Si{sub 1-x}Ge{sub x} layers and their potential in device applications will be reviewed. Among those to be discussed are resonant tunneling, miniband transport, and intersubband absorption in Si{sub 1-x}Ge{sub x}/Si superlattice structures, optical properties of monolayer Si{sub m}Ge{sub n} superlattices, and observation of large Stark effect associated with interband transition between quantized states in Si{sub 1-x}Ge{sub x}/Si quantum well structures.

  11. Preparation and study of odontogenic and porous biphasic bioceramics%牙源性多孔双相生物陶瓷的制备和性能研究

    Institute of Scientific and Technical Information of China (English)

    康林; 吴海珍; 王鑫; 陆钰; 甘朝兵; 王生杰; 杨晓勇

    2014-01-01

    收集临床上离体牙,经高温煅烧去除有机成分,将其与( NH4)2 HPO4溶液混合后再次煅烧,制得以羟基磷灰石( HA)和β-磷酸三钙(β-TCP)为主要成分的双相陶瓷,磨碎过200目筛,用有机泡沫浸渍法制备多孔生物陶瓷,对材料进行物相分析、扫描电镜、孔隙率、元素分析和抗压强度检测。牙源性多孔陶瓷材料呈白色,主要物相为 HA 和β-TCP,为大孔/微孔多孔网状结构,孔隙率为74.85%,Ca/P为1.62,抗压强度应为(3.483±0.321)MPa。%The detachment teeth were calcinated first time in order to remove the organic principle,and second cal-cinated with the aqua of (NH4)2HPO4,then get biphasic bioceramics composed with Hydroxyapatite(HA)and β-tricalcium phosphate(β-TCP) . After grinding through 200 mesh screen,the porous bioceramics was prepared by im-mersion method using organic foam. At the same time,a series of examinations were carried out including energy dispersion analysis of X-ray,scanning electron microscope,the porosity of scaffolds,elemental analysis and compres-sive strength. It showed that the ceramic was white and the main phase was HA/β-TCP,which presented reticular structure with macropore and micropore. The porosity of scaffolds was 74. 85 percent and the calcium to phosphorus ratio of bioceramics was 1. 62. The compressive strength could attain(3.483±0.321)MPa.

  12. Highly sensitive NIR PtSi/Si-nanostructure detectors

    Science.gov (United States)

    Li, Hua-gao; Guo, Pei; Yuan, An-bo; Long, Fei; Li, Rui-zhi; Li, Ping; Li, Yi

    2016-10-01

    We report a high external quantum efficiency (EQE) photodiode detector with PtSi/Si-nanostructures. Black silicon nanostructures were fabricated by metal-assist chemical etching (MCE), a 2 nm Pt layer was subsequently deposited on black silicon surface by DC magnetron sputtering system, and PtSi/Si-nanostructures were formed in vacuum annealing at 450 oC for 5 min. As the PtSi/Si-nanostructures presented a spiky shape, the absorption of incident light was remarkably enhanced for the repeat reflection and absorption. The breakdown voltage, dark current, threshold voltage and responsivity of the device were investigated to evaluate the performance of the PtSi/Si-nanostructures detector. The threshold voltage and dark currents of the PtSi/Si-nanostructure photodiode tends to be slightly higher than those of the standard diodes. The breakdown voltage remarkably was reduced because of existing avalanche breakdown in PtSi/Si-nanostructures. However, the photodiodes had high response at room temperature in near infrared region. At -5 V reverse bias voltage, the responsivity was 0.72 A/W in 1064 nm wavelength, and the EQE was 83.9%. By increasing the reverse bias voltage, the responsivity increased. At -60 V reverse bias voltage, the responsivity was 3.5 A/W, and the EQE was 407.5%, which means the quantum efficiency of PtSi/Si-nanostructure photodiodes was about 10 times higher than that of a standard diode. Future research includes how to apply this technology to enhance the NIR sensitivity of image sensors, such as Charge Coupled Devices (CCD).

  13. SiC-Si interfacial thermal and mechanical properties of reaction bonded SiC/Si ceramic composites

    Science.gov (United States)

    Hsu, Chun-Yen; Deng, Fei; Karandikar, Prashant; Ni, Chaoying

    Reaction bonded SiC/Si (RBSC) ceramic composites are broadly utilized in military, semiconductor and aerospace industries. RBSC affords advanced specific stiffness, hardness and thermal. Interface is a key region that has to be considered when working with any composites. Both thermal and mechanical behaviors of the RBSC are highly dependent on the SiC-Si interface. The SiC-Si interface had been found to act as a thermal barrier in restricting heat transferring at room temperature and to govern the energy absorption ability of the RBSC. However, up to present, the role of the SiC-Si interface to transport heat at higher temperatures and the interfacial properties in the nanoscale have not been established. This study focuses on these critically important subjects to explore scientific phenomena and underlying mechanisms. The RBSC thermal conductivity with volume percentages of SiC at 80 and 90 vol% was measured up to 1,200 °C, and was found to decrease for both samples with increasing environmental temperature. The RBSC with 90 vol% SiC has a higher thermal conductivity than that of the 80 vol%; however, is still significantly lower than that of the SiC. The interfacial thermal barrier effect was found to decrease at higher temperatures close 1200 °C. A custom-made in-situ tensile testing device which can be accommodated inside a ZEISS Auriga 60 FIB/SEM has been setup successfully. The SiC-Si interfacial bonding strength was measured at 98 MPa. The observation and analysis of crack propagation along the SiC-Si interface was achieved with in-situ TEM.

  14. Radiation-induced plasmons in Si-SiO2

    Institute of Scientific and Technical Information of China (English)

    1999-01-01

    The first level plasmons of Si in the pure Si state (corresponding to bonding energy (BE) of 116.95 eV) and in the SiO2 state (corresponding to BE of 122.0 eV) of Si-SiO2 prepared by irradiation hard and soft processing were studied with XPS before and after 60Co radiation.The experimental results indicate thatthere was an interface consisting of the two plasmons,this interface was extended by 60Co radiation, the fractions of the plasmon for Si in the Si-SiO2 werechanged with the variation of radiation dosage,the difference of the change in fraction of plasmonsfor the two kinds of samples was that the soft variedfaster than hard, the change of concentrations inplasmons for both hard and soft Si-SiO2 irradiatedin positive bias field were greater than that in bias-free field.The experimental results are explained from the view point of energy absorbed in form of quantization.

  15. Comparison of thermoelectric properties of nanostructured Mg2Si, FeSi2, SiGe, and nanocomposites of SiGe–Mg2Si, SiGe–FeSi2

    Directory of Open Access Journals (Sweden)

    Amin Nozariasbmarz

    2016-10-01

    Full Text Available Thermoelectric properties of nanostructured FeSi2, Mg2Si, and SiGe are compared with their nanocomposites of SiGe–Mg2Si and SiGe–FeSi2. It was found that the addition of silicide nanoinclusions to SiGe alloy maintained or increased the power factor while further reduced the thermal conductivity compared to the nanostructured single-phase SiGe alloy. This resulted in ZT enhancement of Si0.88Ge0.12–FeSi2 by ∼30% over the broad temperature range of 500-950 °C compared to the conventional Si0.80Ge0.20 alloy. The Si0.88Ge0.12–Mg2Si nanocomposite showed constantly increasing ZT versus temperature up to 950 °C (highest measured temperature reaching ZT ∼ 1.3. These results confirm the concept of silicide nanoparticle-in-SiGe-alloy proposed earlier by Mingo et al. [Nano Lett. 9, 711–715 (2009].

  16. Thermal conductivity/diffusivity of SiC-Mullite and SiC-SiC composites

    OpenAIRE

    1987-01-01

    The purposes of this study were to determine as a function of temperature the thermal diffusivity and/or thermal conductivity of SiC-Mullite and SiC-SiC, and to explain the observed behavior in terms of changes in temperature, microstructure, composition, and/or orientation. Materials used in the SiC-Mullite study consisted of single crystal SiC whiskers (prepared from rice hulls or by the vapor-liquid-solid process) dispersed within a polycrystalline mullite matrix. Dur...

  17. 针对组织工程多孔生物陶瓷的组织学技术优化探讨%Technique improvement of hard tissue slicing of bioceramic scaffold materials applied in bone tissue engineering

    Institute of Scientific and Technical Information of China (English)

    李林; 智伟; 桑力; 张成栋; 李金雨; 张聪; 娄延举; 夏天; 翁杰

    2013-01-01

    目的 改进硬组织切片技术以适应生物陶瓷材料在骨组织工程中的研究.方法 探索硬组织切片的厚度、漂片温度、裱片方法、烤片温度和时间的最佳组合,针对阳离子防脱载玻片的使用条件进行反复比较,通过改进操作流程中的关键技术和需避免的问题,摸索出阳离子载玻片在硬组织切片裱片中的最佳应用条件,克服了硬组织切片制作技术中标本易破碎、切片易脱落及染色时染料容易吸附的缺点.结果 通过技术探索与改进,生物陶瓷支架材料体内植入后的类骨修复体标本的硬组织切片能保持其杂化后的组织结构与比较完整的材料结构,可进行Masson三色染色、苏木精-伊红(HE)及甲苯胺蓝染色.染色后镜下观察显示支架内杂化生长的组织结构完整、细胞形态清晰、切片质量好、生物陶瓷支架脱片少.荧光显微镜可观察到类骨修复体钙沉积现象完整.结论 改善了传统硬组织切片技术处理生物陶瓷材料时易于破坏组织-材料结构的缺点.改进的硬组织切片技术适应生物陶瓷材料在骨组织工程领域研究.%Objective Purpose To improve the hard tissue slicing technology to adapt to the study of the bioceramic materials in bone tissue engineering.Methods Purpose To improve the hard tissue slicing technology to adapt to the study of the bioceramic materials in bone tissue engineering.Results The improved techniques in hard tissue slicing could keep the morphosis and structure of hybrid tissues,and easily stain with Masson,HE and toluidine blue.The stained hard tissue slicing had an intact tissue structure,clear cell form,good slicing quality,little shedding.Fluorescence microscope showed an intact calcium deposition of homologous bone restoration.Conclusion The method overcome the shortcomings of easy to destroy the tissue-material structure happened in the traditional hard tissue slicing of bioceramic materials

  18. DESIGN AND FABRICATION OF Si/SiGe PMOSFETs

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    Based on theoretical analysis and computer-aided simulation, optimized design prin-ciples for Si/SiGe PMOSFET are given in this paper, which include choice of gate materials, determination of germanium percentage and profile in SiGe channel, optimization of thickness of dioxide and silicon cap layer, and adjustment of threshold voltage.In the light of these principles, a SiGe PMOSFET is designed and fabricated successfully.Measurement indicates that the SiGe PMOSFET's(L=2μ同洒45 mS/mm(300K) and 92 mS/mm(77K) ,while that is 33mS/mm (300K) and 39mS/mm (77K) in Si PMOSFET with the same structure.

  19. DESIGN AND FABRICATION OF Si/SiGe PMOSFETs

    Institute of Scientific and Technical Information of China (English)

    Yang Peifeng; Zhang Jing; Yi Qiang; Fan Zerui; Li Jingchun; Yu Qi; Wang Xiangzhan; Yang Mohua; He Lin; Li Kaicheng; Tan Kaizhou; Liu Daoguang

    2002-01-01

    Based on theoretical analysis and computer-aided simulation, optimized design principles for Si/SiGe PMOSFET are given in this paper, which include choice of gate materials,determination of germanium percentage and profile in SiGe channel, optimization of thickness of dioxide and silicon cap layer, and adjustment of threshold voltage. In the light of these principles,a SiGe PMOSFET is designed and fabricated successfully. Measurement indicates that the SiGe PMOSFET's (L=2μm) transconductance is 45 mS/mm (300K) and 92mS/mm (77K), while that is 33 mS/mm (300K) and 39mS/mm (77K) in Si PMOSFET with the same structure.

  20. Synthesis and characterization of laminated Si/SiC composites

    Directory of Open Access Journals (Sweden)

    Salma M. Naga

    2013-01-01

    Full Text Available Laminated Si/SiC ceramics were synthesized from porous preforms of biogenous carbon impregnated with Si slurry at a temperature of 1500 °C for 2 h. Due to the capillarity infiltration with Si, both intrinsic micro- and macrostructure in the carbon preform were retained within the final ceramics. The SEM micrographs indicate that the final material exhibits a distinguished laminar structure with successive Si/SiC layers. The produced composites show weight gain of ≈5% after heat treatment in air at 1300 °C for 50 h. The produced bodies could be used as high temperature gas filters as indicated from the permeability results.

  1. 牛骨原料多孔生物陶瓷的制备及性能表征%PREPARATION AND PROPERTIES OF POROUS BIOCERAMICS MADE OF BOVINE BONE

    Institute of Scientific and Technical Information of China (English)

    丁云飞; 张学斌; 王松林

    2009-01-01

    以煅烧后的牛骨粉体(羟基磷灰石)为原料,以尿素为造孔剂,模压后烧结.制备出多孔生物陶瓷.考察了球磨时间对牛骨粉体粒径的影响,研究了尿素添加量的对多孔陶瓷微结构和力学性能的影响.多孔生物陶瓷的孔隙率约为34%~60%,平均孔径约为110 μm,抗弯强度,压缩强度和弹性模量分别位于40.15MPa~64.72MPa,7.05MPa~10.48MPa,5.98~9.72GPa;微结构和力学性能均能满足人工骨替代材料要求.%The porous hydroxyapatite (HAP) bioceramics was prepared using HAP powder from calcined bovine bone and urea as pore-creating agent. The influence of milling time on the particle size, and the influences of urea content on the micostrcuture and mechanical properties were researched. The average pore size is about 110μm. The porosities distribute from 34%-60%. And the flexural strength, compressive strength and Young's modulus of the porous bioceramics were 40.15MPa~64.72MPa, 7.05MPa~10.48MPa and 5.98~9.72GPa, respectively. All the results can meet the requirements of the human bone substitute.

  2. An efficient Si light-emitting diode based on an n- ZnO/SiO2-Si nanocrystals-SiO2/p-Si heterostructure.

    Science.gov (United States)

    Sun, Edward; Su, Fu-Hsiang; Shih, Ying-Tsang; Tsai, Hung-Ling; Chen, Ching-Huang; Wu, Mong-Kai; Yang, Jer-Ren; Chen, Miin-Jang

    2009-11-04

    Si nanocrystals embedded in a SiO2 matrix and an n-type Al-doped ZnO (ZnO:Al) layer were applied to improve the external quantum efficiency from Si in n- ZnO/SiO2-Si nanocrystals-SiO2/p-Si heterojunction light-emitting diodes (LEDs). The Si nanocrystals were grown by low pressure chemical vapor deposition and the ZnO:Al layer was prepared by atomic layer deposition. The n-type ZnO:Al layer acts as an electron injection layer, a transparent conductive window, and an anti-reflection coating to increase the light extraction efficiency. Owing to the spatial confinement of carriers and surface passivation by the surrounding SiO2, the Si nanocrystals embedded in the SiO2 matrix lead to a significant enhancement of the light emission efficiency from Si. An external quantum efficiency up to 4.3 x 10(-4) at the wavelength corresponding to the indirect bandgap of Si was achieved at room temperature.

  3. 钛合金微弧氧化羟基磷灰石生物活性涂层的摩擦磨损性能研究%Research on Friction and Wear Properties of Micro-arc Oxidation Bioceramic Coating Containing Hydroxyapatite on Ti Alloy

    Institute of Scientific and Technical Information of China (English)

    杨喜臻

    2013-01-01

    Took micro-arc oxidation welding technology, bioceramic coating containing hydroxyapatite (HA) was in-situ synthesized on Ti alloy, the friction and wear properties of the bioceramic coating were studied. The affecting discipline such as wearing time and electric current density and their laws were obtained in the experiment. The results showed that the friction coefficient of bioceramic coating containing hydroxyapatite was first increased and then decreased with the friction time, while the friction coefficient was first decreased and then increased when electricity density increased.%采用微弧氧化技术,在钛合金表面原位合成含有羟基磷灰石的生物活性陶瓷涂层,研究了陶瓷涂层的摩擦磨损性能,得出了不同磨损时间和不同微弧氧化电流密度对陶瓷涂层耐磨性的影响规律.结果表明,含有羟基磷灰石的陶瓷涂层,其摩擦因数随摩擦磨损时间的增加而先增大后减小,其耐磨性随微弧氧化电流密度的增加而先减小后增大.

  4. Al versus Si competition in FeSiAl alloys

    Energy Technology Data Exchange (ETDEWEB)

    Legarra, E. [Dpto. Electricidad y Electronica, Facultad de Ciencia y Tecnologia, Universidad del Pais Vasco (UPV/EHU), CP 644, 48080 Bilbao (Spain)], E-mail: estibaliz.legarra@ehu.es; Apinaniz, E. [Dpto. Fisica Aplicada I, Escuela de Ingenieria Tecnica Superior, Universidad del Pais Vasco, Alameda de Urquijo s/n 48013 Bilbao (Spain); Plazaola, F. [Dpto. Electricidad y Electronica, Facultad de Ciencia y Tecnologia, Universidad del Pais Vasco (UPV/EHU), CP 644, 48080 Bilbao (Spain); Jimenez, J.A. [Centro Nacional de Investigaciones Metalurgicas (CENIM), Avda. Gregorio del amo 8, 28040 Madrid (Spain); Pierna, A.R. [Chemical Engineering and Environmental Department, UPV/EHU, Box 1379, 20008 San Sebastian (Spain)

    2008-10-15

    In FeSiAl alloys, when Si substitutes for Al, important changes take place in the magnetism as well as in the structural properties. Alloys in the two composition series Fe{sub 75}Al{sub 25-x}Si{sub x} (x=0, 7.5, 12.5, 17.5, 25) and Fe{sub 70}Al{sub 30-x}Si{sub x} (x=0, 9, 15, 21, 30) were prepared by induction melting; afterwards they were crushed and then annealed in order to recover the DO{sub 3} stable phase. The deformed FeAl samples show larger lattice parameters than the ordered ones; however, this difference ({delta}a) decreases when Si substitutes for Al until it becomes zero (i.e. until the ordered samples and the deformed ones have the same lattice parameters). This trend is the same for both sample series and does not depend on the Fe content of the alloy. However, the magnetization has a different behaviour depending on the Fe content. For deformed Fe{sub 75}Al{sub 25-x}Si{sub x} alloys the saturation magnetization decreases with increasing Si content while for Fe{sub 70}Al{sub 30-x}Si{sub x} deformed alloys the saturation magnetization has a plateau in which the saturation magnetization values do not vary.

  5. Joining of SiC ceramics and SiC/SiC composites

    Energy Technology Data Exchange (ETDEWEB)

    Rabin, B.H. [Idaho National Engineering Lab., Idaho Falls, ID (United States)

    1995-08-01

    This project has successfully developed a practical and reliable method for fabricating SiC ceramic-ceramic joints. This joining method has the potential to facilitate the use of SiC-based ceramics in a variety of elevated temperature fossil energy applications. The technique is based on a reaction bonding approach that provides joint interlayers compatible with SiC, and excellent joint mechanical properties at temperatures exceeding 1000{degrees}C. Recent efforts have focused on transferring the joining technology to industry. Several industrial partners have been identified and collaborative research projects are in progress. Investigations are focusing on applying the joining method to sintered a-SiC and fiber-reinforced SiC/SiC composites for use in applications such as heat exchangers, radiant burners and gas turbine components.

  6. Joining of SiC ceramics and SiC/SiC composites

    Energy Technology Data Exchange (ETDEWEB)

    Rabin, B.H. [Idaho National Engineering Lab., Idaho Falls, ID (United States)

    1996-08-01

    This project has successfully developed a practical and reliable method for fabricating SiC ceramic-ceramic joints. This joining method will permit the use of SiC-based ceramics in a variety of elevated temperature fossil energy applications. The technique is based on a reaction bonding approach that provides joint interlayers compatible with SiC, and excellent joint mechanical properties at temperatures exceeding 1000{degrees}C. Recent emphasis has been given to technology transfer activities, and several collaborative research efforts are in progress. Investigations are focusing on applying the joining method to sintered {alpha}-SiC and fiber-reinforced SiC/SiC composites for use in applications such as heat exchangers, radiant burners and gas turbine components.

  7. Methods of radiation effects evaluation of SiC/SiC composite and SiC fibers

    Energy Technology Data Exchange (ETDEWEB)

    Youngblood, G.E.; Jones, R.H. [Pacific Northwest National Lab., Richland, WA (United States)

    1998-03-01

    This report covers material presented at the IEA/Jupiter Joint International Workshop on SiC/SiC Composites for Fusion structural Applications held in conjunction with ICFRM-8, Sendai, Japan, Oct. 23--24, 1997. Several methods for radiation effects evaluation of SiC fibers and fiber-reinforced SiC/SiC composite are presented.

  8. Porous bioceramic beta-tricalcium phosphate for treatment of osteonecrosis of the femoral head%磷酸三钙多孔生物陶瓷修复股骨头坏死

    Institute of Scientific and Technical Information of China (English)

    孙伟; 李子荣; 高福强; 史振才; 王佰亮; 郭万首

    2014-01-01

    BACKGROUND:It is a clinical difficult in the treatment of osteonecrosis with joint preservation, and to solve this problem, a variety of bone graft substitutes are at the exploration stage. OBJECTIVE:To evaluate the clinical outcome of lightbulb operation with porous bioceramic β-tricalcium phosphate in a consecutive series of patients with osteonecrosis of the femoral head. METHODS:From January to December 2008, 58 patients (88 hips) who had undergone lightbulb operation with porous bioceramic β-tricalcium phosphate were involved in this study. Al patients were evaluated both clinicaly and radiographicaly at postoperative 3, 6, 12 months and annualy. Functional improvement was assessed with the Harris hip score. RESULTS AND CONCLUSION: Among these patients, 56 patients (85 hips) were folowed up for 2-5 years. According to the ARCO staging system, there were 27 hips of stage II, 40 hips of stage IIIa, 18 hips of IIIb. According to the hospital’s classification, type C was in 4 hips, L1 in 15 hips, L2 in 28 hips, and L3 in 38 hips. According to the Harris hip score system, excelent outcome was in 55 hips, good in 12 hips, fair in 5 hips and poor in 13 hips. Nine of 11 patients who failed to preserve their own joints were subjected to hip replacement. The  mean preoperative and postoperative Harris scores were 61.2 and 85.3, respectively, with a mean improvement of 24.1 points (P < 0.001). All hips were radiologically stable, with no progress of osteonecrosis, and bone density in the bone graft area increased obviously. The replacement time of porous bioceramic β-tricalcium phosphate was 1-1.5 years. These findings suggest that the porous bioceramic β-tricalcium phosphate provides an option to treat osteonecrosis of the femoral head with satisfactory clinical outcomes, and profits the repair and reconstruction of femoral head osteonecrosis. When in the lateral column of femoral head, the porous bioceramic β-tricalcium phosphate can play a supporting role

  9. Improvement of parameters in a-Si(p)/c-Si(n)/a-Si(n) solar cells

    Science.gov (United States)

    Moustafa Bouzaki, Mohammed; Aillerie, Michel; Ould Saad Hamady, Sidi; Chadel, Meriem; Benyoucef, Boumediene

    2016-10-01

    We analyzed and discussed the influence of thickness and doping concentration of the different layers in a-Si(p)/c-Si(n)/a-Si(n) photovoltaic (PV) cells with the aim of increasing its efficiency while decreasing its global cost. Compared to the efficiency of a standard marketed PV cell, elaborated with a ZnO transparent conductive oxide (TCO) layer but without Back Surface Field (BSF) layer, an optimization of the thickness and dopant concentration of both the emitter a-Si(p) and absorber c-Si(n) layers will gain about 3% in the global efficiency of the cell. The results also reveal that with introduction of the third layer, i.e. the BSF layer, the efficiency always achieves values above 20% and all other parameters of the cell, such as the open-circuit voltage, the short-circuit current and the fill-factor, are strongly affected by the thickness and dopant concentration of the layers. The values of all parameters are given and discussed in the paper. Thereby, the simulation results give for an optimized a-Si(p)/c-Si(n)/a-Si(n) PV cells the possibility to decrease the thickness of the absorber layer down to 50 μm which is lower than in the state-of-the-art. This structure of the cell achieves suitable properties for high efficiency, cost-effectiveness and reliable heterojunction (HJ) solar cell applications.

  10. Biomorphous SiSiC/Al-Si ceramic composites manufactured by squeeze casting: microstructure and mechanical properties

    Energy Technology Data Exchange (ETDEWEB)

    Zollfrank, C.; Travitzky, N.; Sieber, H.; Greil, P. [Department of Materials Science, Glass and Ceramics, University of Erlangen-Nuernberg (Germany); Selchert, T. [Advanced Ceramics Group, Technical University of Hamburg-Harburg (Germany)

    2005-08-01

    SiSiC/Al-Si composites were fabricated by pressure-assisted infiltration of an Al-Si alloy into porous biocarbon preforms derived from the rattan palm. Al-Si alloy was found in the pore channels of the biomorphous SiSiC preform, whereas SiC and carbon were present in the struts. The formation of a detrimental Al{sub 4}C{sub 3}-phase was not observed in the composites. A bending strength of 200 MPa was measured. The fractured surfaces showed pull-out of the Al-alloy. (Abstract Copyright [2005], Wiley Periodicals, Inc.)

  11. Fabrication and Mechanical Properties of SiCw(p/SiC-Si Composites by Liquid Si Infiltration using Pyrolysed Rice Husks and SiC Powders as Precursors

    Directory of Open Access Journals (Sweden)

    Dan Zhu

    2014-03-01

    Full Text Available Dense silicon carbide (SiC matrix composites with SiC whiskers and particles as reinforcement were prepared by infiltrating molten Si at 1550 °C into porous preforms composed of pyrolysed rice husks (RHs and extra added SiC powder in different ratios. The Vickers hardness of the composites showed an increase from 18.6 to 21.3 GPa when the amount of SiC added in the preforms was 20% (w/w, and then decreased to 17.3 GPa with the increase of SiC added in the preforms up to 80% (w/w. The values of flexural strength of the composites initially decreased when 20% (w/w SiC was added in the preform and then increased to 587 MPa when the SiC concentration reached 80% (w/w. The refinement of SiC particle sizes and the improvement of the microstructure in particle distribution of the composites due to the addition of external SiC played an effective role in improving the mechanical properties of the composites.

  12. Shock compaction of bioceramic composites

    NARCIS (Netherlands)

    Stuivinga, M.E.C.; Carton, E.P.; Wijn, J.R. de

    2000-01-01

    A method was developed for making dense hydroxyapatite-polymer composites. Hydroxyapatite (HA) is a type of calcium phosphate, which is a bioactive material. The polymer used in this work was Polyactive™ 60/40, a block copolymer from polyethylene oxide (PEO) and polybutylene terephtalate (PBT) in a

  13. Fabrication and evaluation of propagation loss of Si/SiGe/Si photonic-wire waveguides for Si based optical modulator

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Younghyun, E-mail: yhkim@mosfet.t.u-tokyo.ac.jp [Department of Electrical Engineering and Information Systems, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-8656 (Japan); Takenaka, Mitsuru [Department of Electrical Engineering and Information Systems, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-8656 (Japan); Osada, Takenori; Hata, Masahiko [Sumitomo Chemical Co. Ltd., 6 Kitahara, Tsukuba, Ibaraki 300-3294 (Japan); Takagi, Shinichi [Department of Electrical Engineering and Information Systems, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-8656 (Japan)

    2014-04-30

    We have characterized photonic-wire waveguides with Si/SiGe/Si heterostructure ribs for Si-based optical modulators. The Si (80 nm)/Si{sub 0.72}Ge{sub 0.28} (40 nm) layers grown on Si-on-insulator by molecular beam epitaxy for optical modulators were evaluated by in-situ reflection high-energy electron diffraction, atomic force microscope, X-ray diffraction and Raman spectroscopy, exhibiting that the fully-strained highly-crystalline SiGe layer was obtained. We have evaluated the propagation loss of the Si/strained SiGe/Si photonic-wire waveguides. The wavelength dependence of the propagation loss exhibits the bandgap narrowing of the strained Si{sub 0.72}Ge{sub 0.28}, while the optical absorption of the strained Si{sub 0.72}Ge{sub 0.28} is not significant for the optical modulator application at 1.55-μm wavelength. - Highlights: • We have characterized photonic-wire waveguides with Si/SiGe/Si heterostructure ribs. • The Si/Si{sub 0.72}Ge{sub 0.28} grown on Si-on-insulator were evaluated to be fully strained. • We have fabricated and evaluated the Si/strained SiGe/Si photonic-wire waveguides. • The wavelength dependence exhibits bandgap narrowing of the strained Si{sub 0.72}Ge{sub 0.28}. • Optical absorption of the SiGe is not significant for optical modulators at 1.55 μm.

  14. Si Isotopes of Brownleeite

    Science.gov (United States)

    Nakamura-Messenger, K.; Messenger, Scott R.; Ito, M.; Keller, L. P.; Clemett, S. J.; Jones, J. H.; Tatsuoka, H.; Zolensky, M. E.; Tatsuoka, H.

    2010-01-01

    Brownleeite is a manganese silicide, ideally stoichiometric MnSi, not previously observed in nature until its discovery within an interplanetary dust particle (IDP) that likely originated from a comet [1]. Three discrete brownleeite grains in the IDP L2055 I3 (4 microns in size, hereafter IDP I3) were identified with maximum dimensions of 100, 250 and 600 nm and fully analyzed using scanning-transmission electron microscopy (STEM) [1]. One of the grains (100 nm in size) was poikilitically enclosed by low-Fe, Mn-enriched (LIME) olivine. LIME olivine is epitaxial to the brownleeite with the brownleeite (200) parallel to the olivine c* [1]. LIME olivine is an enigmatic phase first reported from chondritic porous IDPs and some unequilibrated ordinary chondrites [ 2], that is commonly observed in chondritic-porous IDPs. Recently, LIME olivine has been also found in comet Wild-2 (Stardust) samples [3], indicating that LIME olivine is a common mineral component of comets. LIME olivine has been proposed to form as a high temperature condensate in the protosolar nebula [2]. Brownleeite grains also likely formed as high-temperature condensates either in the early Solar System or in the outflow of an evolved star or supernova explosion [1]. The isotopic composition of the brownleeite grains may strongly constrain their ultimate source. To test this hypothesis, we performed isotopic analyses of the brownleeite and the associated LIME olivine, using the NASA/JSC NanoSIMS 50L ion microprobe.

  15. Organic thin film transistors with a SiO2/SiNx/SiO2 composite insulator layer

    Institute of Scientific and Technical Information of China (English)

    Liu Xiang; Liu Hui

    2011-01-01

    We have investigated a SiO2/SiNx/SiO2 composite insulation layer structured gate dielectric for an organic thin film transistor (OTFT) with the purpose of improving the performance of the SiO2 gate insulator.The SiO2/SiNx/SiO2 composite insulation layer was prepared by magnetron sputtering.Compared with the same thickness of a SiO2 insulation layer device,the SiO2/SiNx/SiO2 composite insulation layer is an effective method of fabricating OTFT with improved electric characteristics and decreased leakage current.Electrical parameters such as carrier mobility by field effect measurement have been calculated.The performances of different insulating layer devices have been studied,and the results demonstrate that when the insulation layer thickness increases,the off-state current decreases.

  16. Study of New Way about Si/Si Bonding

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    A new set of technique was adopted in bonding Si-Si by using Ge (Ⅳ element),which is used as the substitute for the common hydrophilic method. The bond layer has no holes, and the edge bond-rate amounts to above 98%, and the bond strength is above 2156 Pa. By doping the same kind of dopant with low-resistance in Ge, the stress compensation was realized.

  17. Formation of microtubes from strained SiGe/Si heterostructures

    Energy Technology Data Exchange (ETDEWEB)

    Qin, H [Laboratory of Molecular-scale Engineering, Department of Electrical and Computer Engineering, University of Wisconsin-Madison, 1415 Engineering Drive, Madison, WI 53706 (United States); Shaji, N [Laboratory of Molecular-scale Engineering, Department of Electrical and Computer Engineering, University of Wisconsin-Madison, 1415 Engineering Drive, Madison, WI 53706 (United States); Merrill, N E [Laboratory of Molecular-scale Engineering, Department of Electrical and Computer Engineering, University of Wisconsin-Madison, 1415 Engineering Drive, Madison, WI 53706 (United States); Kim, H S [Laboratory of Molecular-scale Engineering, Department of Electrical and Computer Engineering, University of Wisconsin-Madison, 1415 Engineering Drive, Madison, WI 53706 (United States); Toonen, R C [Laboratory of Molecular-scale Engineering, Department of Electrical and Computer Engineering, University of Wisconsin-Madison, 1415 Engineering Drive, Madison, WI 53706 (United States); Blick, R H [Laboratory of Molecular-scale Engineering, Department of Electrical and Computer Engineering, University of Wisconsin-Madison, 1415 Engineering Drive, Madison, WI 53706 (United States); Roberts, M M [Department of Materials Science and Engineering, University of Wisconsin-Madison, 1500 Engineering Drive, Madison, WI 53706 (United States); Savage, D E [Department of Materials Science and Engineering, University of Wisconsin-Madison, 1500 Engineering Drive, Madison, WI 53706 (United States); Lagally, M G [Department of Materials Science and Engineering, University of Wisconsin-Madison, 1500 Engineering Drive, Madison, WI 53706 (United States); Celler, G [SOITEC USA Inc., 2 Centennial Drive, Peabody, MA 01960 (United States)

    2005-11-15

    We report the formation of micrometre-sized SiGe/Si tubes by releasing strained SiGe/Si bilayers from substrates in a wet chemical-etching process. In order to explore statistical studies of dynamic formation of microtubes, we fabricated arrays of square bilayers. Due to the dynamic change in curvature of the bilayers, and hence the underlying etch channels, the etching process deviates from a transport-controlled regime to one of kinetic controlled. We identified two distinct modes of etching. A slow etching mode is associated with symmetric surface deformation in which the bilayers mostly retain their initial pattern. In the fast mode, bilayers are asymmetrically deformed while large etch channels are induced and etching becomes kinetically controlled. Etch rate dispersion is directly related to the degree of asymmetry in surface deformation. When the dimensions of the bilayers become significantly larger than the curvature radius, kinetic etching dominates. During the formation of tubes, SiGe/Si bilayers strongly interact with the liquid environment of etchant and solvent. Assisted by the surface tension of evaporating liquids, the tubes are drawn near the substrate and eventually fixed to it because of van der Waals forces. Our study illuminates the dynamic etching and curling processes involved with and provides insight on how a uniform etch rate and consistent curling directions can be maintained.

  18. Formation of microtubes from strained SiGe/Si heterostructures

    Science.gov (United States)

    Qin, H.; Shaji, N.; Merrill, N. E.; Kim, H. S.; Toonen, R. C.; Blick, R. H.; Roberts, M. M.; Savage, D. E.; Lagally, M. G.; Celler, G.

    2005-11-01

    We report the formation of micrometre-sized SiGe/Si tubes by releasing strained SiGe/Si bilayers from substrates in a wet chemical-etching process. In order to explore statistical studies of dynamic formation of microtubes, we fabricated arrays of square bilayers. Due to the dynamic change in curvature of the bilayers, and hence the underlying etch channels, the etching process deviates from a transport-controlled regime to one of kinetic controlled. We identified two distinct modes of etching. A slow etching mode is associated with symmetric surface deformation in which the bilayers mostly retain their initial pattern. In the fast mode, bilayers are asymmetrically deformed while large etch channels are induced and etching becomes kinetically controlled. Etch rate dispersion is directly related to the degree of asymmetry in surface deformation. When the dimensions of the bilayers become significantly larger than the curvature radius, kinetic etching dominates. During the formation of tubes, SiGe/Si bilayers strongly interact with the liquid environment of etchant and solvent. Assisted by the surface tension of evaporating liquids, the tubes are drawn near the substrate and eventually fixed to it because of van der Waals forces. Our study illuminates the dynamic etching and curling processes involved with and provides insight on how a uniform etch rate and consistent curling directions can be maintained.

  19. The origin of blue photoluminescence from nc-Si/SiO2 multilayers

    Institute of Scientific and Technical Information of China (English)

    Ma Zhong-Yuan; Xu Ling; Huang Xin-Fan; Chen Kun-Ji; Feng Duan; Guo Si-Hua; Chen De-Yuan; Wei De-Yuan; Yao Yao; Zhou Jiang; Huang Rui; Li Wei; Xu Jun

    2008-01-01

    Intensive blue photoluminescence (PL) was observed at room temperature from the nanocrystalline-Si/SiO2 (ncSi/SiO2) multilayers (MLs) obtained by thermal annealing of SiO/SiO2 MLs for the first time.By controlling the size of nc-Si formed in SiO sublayer from 3.5 to 1.5 nm,the PL peak blueshifts from 457 to 411 nm.Combining the analysis of TEM,Raman and absorption measurement,this paper attributes the blue PL to multiple luminescent centres at the interface of nc-Si and SiO2.

  20. SiC/Si's CRYSTALLOGRAPHIC ORIENTATION RELATIONSHIP IN SiCp/Al-Si COMPOSITES%SiCp/Al-Si复合材料中SiC/Si的晶体学位向关系

    Institute of Scientific and Technical Information of China (English)

    隋贤栋; 罗承萍; 欧阳柳章; 骆灼旋

    2000-01-01

    用TEM研究了离心铸造和挤压铸造的SiCp/ZL109复合材料,发现Si优先在SiC表面上形核、长大,并形成大量"界面Si"及SiC/Si界面.SiC与Si之间不存在固定的晶体学位向关系,但存在(1101)sic//(111)si,[1120]sic∥[112]si优先出现的位向关系,而(0001)sic∥(111)si不是优先出现的位向关系.

  1. 钛基植人物生物陶瓷涂层的研究进展%Research of bio-ceramic coatings on Ti-based implants in biomedical application

    Institute of Scientific and Technical Information of China (English)

    余将明; 叶晓健; 万俊明; 宋玉林

    2011-01-01

    Titanium alloy has been used widely in fields of hard tissue replacement and repair,despite its characteristics of bio-inert material.Bio-ceramic coating deposited on Ti-based implants surface using surface modification technique can improve the bioactivity and biocompatibility of Ti-alloy material.The hydroxyapatite coating has been applied in clinic treatment,but this type of coating is still plagued with low crystallinity and poor bonding strength.In order to obtain an implant with excellent integrated properties,some novel bio-ceramic coating materials have been prepared.These materials having excellent bioactivity and biocompatibility and can directly bond with the Ti-based implants and the bone tissue.This review will present research status of the application of bio-ceramic coating on titanium alloy surface in biomedical fields%医用钛合金材料属于生物惰性材料,广泛应用于硬组织的替换与修复领域.采用表面改性技术在钛基材料表面制成生物陶瓷涂层可改善钛基材料的生物活性和生物相容性.羟基磷灰石涂层已在临床上获得应用,但使用效果仍然受其较低的结合强度和结晶度所制约.为了获得综合性能更好的植入材料,制备了多种新型生物陶瓷涂层,其具有良好的生物活性、较好的结合强度及与骨组织能有效结合的能力.综述了钛及钛合金材料表面的生物陶瓷涂层在生物医学领域应用的研究进展.

  2. 低含量污染物下悬浮填料移动床耐冲击负荷试验研究%INFLUENCE OF AERATION RATE ON REMOVAL EFFICIENCY IN BIO-CERAMIC MOVING BED BIOFILM REACTOR

    Institute of Scientific and Technical Information of China (English)

    周艾文; 金腊华; 魏臻

    2011-01-01

    Using bio-ceramic as a filler in MBBR reactor to purify southen town's low-concentration domestic sewage, the effects of the influential factors by different hydraulic load and organic load on a MBBR reactor had been studied, and further explored the boundary conditions of system operation.The results revealed that: the bio-ceramic MBBR could affordable 0.9 m3·m-2·h-1 of the hydraulic loading, the removal rate of COD, NH4+-N, TN reached to 64.71%, 58.12%, 37.54%; HRT was 6 h,the system could withstand less than 1.0 kg·m-3·d-1 of organic loading shock, the effluent of COD,NH4+-N, TN could meet l-class criteria of urban wastewater treatment plant emission standards (GB 18918-2002).%利用生物陶粒作为悬浮填料移动床(MBBR)的填料处理南方城镇低含量污染物生活污水,考察了水力负荷、有机负荷对反应器运行性能的影响,进一步探究系统运行边界条件.结果表明,生物陶粒MBBR最高可承受0.9m3·m-2·h-1的水力负荷,COD、NH4+-N、TN去除率分别为64.71%、58.12%、37.54%;HRT为6 h条件下,系统可承受低于1.0kg·m-3·d-1的有机负荷冲击,出水COD和NN4+-N、TN的质量浓度均可达到GB 18918-2002一级标准.

  3. Dimensionless Units in the SI

    CERN Document Server

    Mohr, Peter J

    2014-01-01

    The International System of Units (SI) is supposed to be coherent. That is, when a combination of units is replaced by an equivalent unit, there is no additional numerical factor. Here we consider dimensionless units as defined in the SI, {\\it e.g.} angular units like radians or steradians and counting units like radioactive decays or molecules. We show that an incoherence may arise when different units of this type are replaced by a single dimensionless unit, the unit "one", and suggest how to properly include such units into the SI in order to remove the incoherence. In particular, we argue that the radian is the appropriate coherent unit for angles and that hertz is not a coherent unit in the SI. We also discuss how including angular and counting units affects the fundamental constants.

  4. SiC-SiC and C-SiC Honeycomb for Advanced Flight Structures Project

    Data.gov (United States)

    National Aeronautics and Space Administration — The proposed project builds upon the work done in Phase I with the development of a C-SiC CMC honeycomb material that was successfully tested for mechanical...

  5. SEMICONDUCTOR MATERIALS Photoelectric conversion characteristics of ZnO/SiC/Si heterojunctions

    Science.gov (United States)

    Xiaopeng, Wu; Xiaoqing, Chen; Lijie, Sun; Shun, Mao; Zhuxi, Fu

    2010-10-01

    A series of n-ZnO/n-SiC/p-Si and n-ZnO/p-Si heterojunctions were prepared by DC sputtering. Their structural properties, I—V curves, photovoltaic effects and photo-response spectra were studied. The photoelectric conversion characteristics of n-ZnO/n-SiC/p-Si and n-ZnO/p-Si heterojunctions were investigated. It is found that the photoelectric conversion efficiency of the n-ZnO/n-SiC/p-Si heterojunction is about four times higher than that of the n-ZnO/p-Si heterojunction. The photovoltaic response spectrum indicated that the photoresponse curve of n-ZnO/n-SiC/p-Si increased more strongly than that of n-ZnO/p-Si with the wavelength increasing. It shows that the photoresponse of n-ZnO/p-Si can be enhanced when inserting a 3C-SiC layer between ZnO and Si. There is one inflexion in the photocurrent response curve of the n-ZnO/p-Si heterojunction and two inflexions in that of the n-ZnO/n-SiC/p-Si heterojunction. It is clear that the 3C-SiC plays an important role in the photoelectric conversion of the n-ZnO/n-SiC/p-Si heterojunction.

  6. THE STRUCTURE OF LIQUID LI-SI ALLOYS

    NARCIS (Netherlands)

    DEJONG, PHK; VERKERK, P; VANDERLUGT, W; DEGRAAF, LA

    1993-01-01

    The reverse Monte Carlo method is used to analyse neutron diffraction data on liquid Li65Si35. A well defined Si-Si partial pair correlation function is obtained with strong indications for covalent Si-Si bonds. It is also clear that most of the Si4 stars and Si5 rings occurring in solid Li12Si7 hav

  7. Ionic S(N)i-Si Nucleophilic Substitution in N-Methylaniline-Induced Si-Si Bond Cleavages of Si2Cl6.

    Science.gov (United States)

    Zhang, Jie; Xie, Ju; Lee, Myong Euy; Zhang, Lin; Zuo, Yujing; Feng, Shengyu

    2016-03-24

    N-Methylaniline-induced Si-Si bond cleavage of Si2Cl6 has been theoretically studied. All calculations were performed by using DFT at the MPWB1K/6-311++G(3df,2p)//MPWB1K/6-31+G(d,p) levels. An ionic SN i-Si nucleophilic substitution mechanism, which is a newly found nucleophilic substitution in silicon-containing compounds, is proposed in the N-methylaniline-induced Si-Si bond cleavage in Si2Cl6. Unlike general S(N)i-Si nucleophilic substitutions that go through a pentacoordinated silicon transition state, ionic nucleophilic substitution goes through a tetracoordinated silicon transition state, in which the Si-Si bond is broken and siliconium ions are formed. Special cleavage of the Si-Si bond is presumably due to the good bonding strength between Si and N atoms, which leads to polarization of the Si-Si bond and eventually to heterolytic cleavage. Calculation results show that, in excess N-methylaniline, the final products of the reaction, including (NMePh)(3-n) SiHCl(n) (n=0-2) and (NMePh)(4-n) SiCl(n) (n=2-3), are the Si-Si cleavage products of Si2Cl6 and the corresponding amination products of the former. The ionic S(N)i-Si nucleophilic substitution mechanism can also be employed to describe the amination of chlorosilane by N-methylaniline. The suggested mechanisms are consistent with experimental data.

  8. An Introduction to the New SI

    Science.gov (United States)

    Knotts, Sandra; Mohr, Peter J.; Phillips, William D.

    2017-01-01

    Plans are under way to redefine the International System of Units (SI) around 2018. The new SI specifies the values of certain physical constants to define units. This article explains the new SI in order to provide a resource for high school teachers as well as for advanced students already familiar with the pre-2018 SI.

  9. Revealing heterogeneous nucleation of primary Si and eutectic Si by AlP in hypereutectic Al-Si alloys.

    Science.gov (United States)

    Li, Jiehua; Hage, Fredrik S; Liu, Xiangfa; Ramasse, Quentin; Schumacher, Peter

    2016-04-28

    The heterogeneous nucleation of primary Si and eutectic Si can be attributed to the presence of AlP. Although P, in the form of AlP particles, is usually observed in the centre of primary Si, there is still a lack of detailed investigations on the distribution of P within primary Si and eutectic Si in hypereutectic Al-Si alloys at the atomic scale. Here, we report an atomic-scale experimental investigation on the distribution of P in hypereutectic Al-Si alloys. P, in the form of AlP particles, was observed in the centre of primary Si. However, no significant amount of P was detected within primary Si, eutectic Si and the Al matrix. Instead, P was observed at the interface between the Al matrix and eutectic Si, strongly indicating that P, in the form of AlP particles (or AlP 'patch' dependent on the P concentration), may have nucleated on the surface of the Al matrix and thereby enhanced the heterogeneous nucleation of eutectic Si. The present investigation reveals some novel insights into heterogeneous nucleation of primary Si and eutectic Si by AlP in hypereutectic Al-Si alloys and can be used to further develop heterogeneous nucleation mechanisms based on adsorption.

  10. Si/SiGe/Si HBT直流特性的可靠性%Reliability of DC characteristics in mesa Si/SiGe/Si HBT

    Institute of Scientific and Technical Information of China (English)

    崔福现; 张万荣

    2003-01-01

    对单台面SiGe HBT在E-B结反偏应力下直流特性的可靠性进行了研究.研究结果表明,随应力时间的增加,开启电压增加,直流电流增益下降,特别是在低E-B正偏电压时下降明显;而交流电流增益退化缓慢.

  11. Quantum wells based on Si/SiO{sub x} stacks for nanostructured absorbers

    Energy Technology Data Exchange (ETDEWEB)

    Berghoff, B.; Suckow, S.; Roelver, R.; Spangenberg, B.; Kurz, H. [Institute of Semiconductor Electronics, RWTH Aachen University, Sommerfeldstr. 24, 52074 Aachen (Germany); Sologubenko, A.; Mayer, J. [Central Facility for Electron Microscopy, RWTH Aachen University, Ahornstr. 55, 52074 Aachen (Germany); Ernst Ruska Centre for Microscopy and Spectroscopy with Electrons, Research Centre Juelich, 52426 Juelich (Germany)

    2010-11-15

    We report on electrical transport and quantum confinement in thermally annealed Si/SiO{sub x} multiple quantum well (QW) stacks. Results are correlated with the morphology of the stacks. High temperature annealing of Si/SiO{sub x} stacks leads to precipitation of excess Si from the SiO{sub x} layers, which enhances the degree of crystallization and increases the grain sizes in the Si QWs compared to the conventional Si/SiO{sub 2} system. Moreover, the excess Si forms highly conductive pathways between adjacent Si QWs that are separated by ultrathin silicon oxide barriers. This results in an increase of conductivity by up to 10 orders of magnitude compared to the tunneling dominated transport in Si/SiO{sub 2} stacks. The stacks exhibit a distinct quantum confinement as confirmed by photoluminescence measurements. (author)

  12. Bone Tissue Response to Nano-HA-ZrO2 Compound Bioceramics%纳米增韧HA-ZrO2生物陶瓷与骨缺损断面的结合性能观察

    Institute of Scientific and Technical Information of China (English)

    孟志兵; 唐月军; 郭军; 吕春堂; 周中华

    2013-01-01

    目的:观察纳米增韧HA-ZrO2生物陶瓷植入体与骨断面的结合情况.方法:12只健康成年新西兰大白兔,双侧下颌骨制备洞穿性骨缺损,一侧植入纳米增韧HA-ZrO2生物陶瓷,对侧植入HA(羟基磷灰石)材料,4、8、12周时取材,进行X线摄片观察、材料顶出实验、硬组织切片,比较观察2组骨与材料界面结合情况.结果:X线片和硬组织切片观察结果显示4、8周时HA-ZrO2、HA和骨断面结合不良,12周时发现两种材料均和骨断面结合良好,少部分区域有纤维组织包绕.4、8、12周纳米增韧HA-ZrO2组抗剪切强度分别为(2.36±1.04)、(10.65±1.48)和(30.95±3.67)MPa,不同时间段的组内差异有统计学意义;4、8、12周HA组抗剪切强度分别为(2.27±1.12)、(12.33±1.57)和(31.05±3.44)MPa,不同时间段组内比较差异有统计学意义(P<0.01);但同时间段的结果组间比较,差异无统计学意义(P>0.05).结论:初步认为纳米增韧HA-ZrO2生物陶瓷和骨断面,可以取得与HA类似的较好结合,但是如何在尽量短的时间内使其与骨断面完全结合,还需要进一步的研究.%Objective:The purpose of the present study was to observe the combination of the interface between nanoHA-ZrO2 compound bioceramics and bone tissue.Methods:12 healthy adult New Zealand rabbits were used in the study.Nano-HA-ZrO2 compound bioceramics were placed in one side of the mandible.On the other side,HA were placed as control.Animals were sacrificed at 4、8、12 weeks after operation,histological sections and the interface shear strength were evaluated.X-ray examination were also performed to observe the interface between the bone,nano-HA-ZrO2,and HA bioceramics materials.Results:Hard tissue section and X-rays examination showed a good interface osseointegration appeared at 12 weeks in nano-HA-ZrO2 ceramic group,as well as in HA group.Fibrous tissue manifested in some areas of the interface.Incomplete osseointegration were shown in the

  13. Construction and characterization of spherical Si solar cells combined with SiC electric power inverter

    Science.gov (United States)

    Oku, Takeo; Matsumoto, Taisuke; Hiramatsu, Kouichi; Yasuda, Masashi; Shimono, Akio; Takeda, Yoshikazu; Murozono, Mikio

    2015-02-01

    Spherical silicon (Si) photovoltaic solar cell systems combined with an electric power inverter using silicon carbide (SiC) field-effect transistor (FET) were constructed and characterized, which were compared with an ordinary Si-based converter. The SiC-FET devices were introduced in the direct current-alternating current (DC-AC) converter, which was connected with the solar panels. The spherical Si solar cells were used as the power sources, and the spherical Si panels are lighter and more flexible compared with the ordinary flat Si solar panels. Conversion efficiencies of the spherical Si solar cells were improved by using the SiC-FET.

  14. Si{endash}N linkage in ultrabright, ultrasmall Si nanoparticles

    Energy Technology Data Exchange (ETDEWEB)

    Rogozhina, E.; Belomoin, G.; Smith, A.; Abuhassan, L.; Barry, N.; Akcakir, O.; Braun, P. V.; Nayfeh, M. H.

    2001-06-04

    Ultrabright ultrasmall ({similar_to}1 nm) blue luminescent Si{sub 29} nanoparticles are chlorinated by reaction with Cl{sub 2} gas. A Si{endash}N linkage is formed by the reaction of the chlorinated particles with the functional amine group in butylamine. Fourier transform infrared spectroscopy and x-ray photospectroscopy measurements confirm the N linkage and the presence of the butyl group, while emission, excitation, and autocorrelation femtosecond optical spectroscopy show that, after the linkage formation, the particles with the ultrabright blue luminescent remain, but with a redshift of 40 nm. {copyright} 2001 American Institute of Physics.

  15. Reactive diffusion bonding of SiCp/Al composites by insert layers of mixed Al-Si and Al-Si-SiC powders

    Institute of Scientific and Technical Information of China (English)

    Jihua Huang; Yueling Dong; Yun Wan; Jiangang Zhang; Hua Zhang

    2005-01-01

    Mixed Al-Si and Al-Si-SiC powders were employed as insert layers to reactive diffusion bond SiCp/6063 MMC (metal matrix composites). The results show that SiCp/6063 MMC joints bonded by the insert layer of the mixed Al-Si powder have a dense joining layer with a typical hypoeutectic microstructure. Using the mixed Al-Si-SiC powder as the insert layer, SiCp/6063 MMC can be reactive diffusion bonded by a composite joint. Because of the SiC segregation, however, there are a number of porous zones in the joining layer, which results in the bad shear strength of the joints reactive diffusion bonded by the insert layer of the mixed Al-SiSiC powder, even lower than that of the joints reactive diffusion bonded by the insert layer of the mixed Al-Si powder. Ti and Mg added in the insert layers obviously improve the strength of the joints reactive diffusion bonded by the insert layer of the mixed AlSi-SiC powder, especially, Mg has a more obvious effect.

  16. Effect of Different Nd2O3 Contents on Performances of Rare Earth Active Bioceramic Gradient Coating Produced by Wide-Band Laser Cladding%Nd2O3含量对宽带激光熔覆生物活性稀土梯度涂层性能的影响

    Institute of Scientific and Technical Information of China (English)

    汪震; 刘其斌; 肖明; 杨邦成

    2011-01-01

    为了减少激光熔覆过程中基材与生物陶瓷涂层之间的热应力,提高涂层与基材的结合强度,设计了一种稀土活性生物梯度陶瓷涂层,采用宽带激光熔覆技术,在TC4合金上制备了含HA+β-TCP稀土活性梯度生物陶瓷复合涂层.利用扫描电镜(SEM)、X射线衍射(XRD)、模拟体液(SBF)以及电化学分析仪等手段对涂层组织结构、生物活性及耐腐蚀性进行了研究.结果表明,生物活性稀土梯度涂层分为基材、合金化层以及生物陶瓷层3个层次,且各梯度层之间均为良好的化学冶金结合;稀土氧化物Nd2 O3在宽带激光熔覆生物陶瓷的过程中具有催化合成HA+β-TCP的作用,且当Nd2 O3质量分数为0.6% 时,催化合成HA+β-TCP的量最多;当Nd2 O3质量分数为0.4% ~0.6% 时,涂层的耐腐蚀性最好且涂层表面沉积的磷灰石相的量最多,具有最佳的生物活性.%To decrease the thermal stress and raise the bonding strength between substrate and bioceramic coating during laser cladding, a rare earth active bioceramic gradient coating is designed. The rare earth active gradient bioceramic coating with HA and β-TCP on TC4 allloy is prepared by using wide-band laser cladding technique. The microstructure, bioactivity and corrosion resistance of bioceramic coating are analyzed by scanning electron microscope (SEM), X-ray diffraction (XRD), simulated body fluid (SBF), and electrochemical analyzer. The experimental results show that the bioactive rare earth gradient coating which has excellent chemical metallurgy bonding at the interface consists of substrate, alloying layer and bioceramic coating. Nd2O3 plays an important role in synthesizing HA and β-TCP during wide-band laser cladding. When the mass fraction of Nd2O3 is up to 0.6%, the amount of HA+β-TCP catalyzed during wide-band laser cladding becomes the largest. When the mass fraction of Nd2O3 is 0.4 % ~ 0.6 %, the corrosion resistance of bioceramic coating is

  17. 复合头孢曲松钠和BMP的壳聚糖抗菌成骨生物陶瓷的制备实验研究%Antimicrobiai bioceramic combined with chitosan and ceftriaxone sodium:Preparation and its in vitro and in vivo study

    Institute of Scientific and Technical Information of China (English)

    夏睿; 方诗元; 徐玮; 张亮; 董行; 赵伟亮; 方月娥

    2009-01-01

    Objective To synthesize antimicrobial bioceramic using chitosan and calcium phosphate cements mixed with ceftriaxone sodium. Methods The bioceramic was synthesized through the hardening of chitosan liquid combined with calcium phosphate cements and cefiriaxone sodium.The released ceftriaxone sodium was studied according to the linear equation between UV-VIS absorbance to concentration.The in vitro bactefiostatic effect of the chosen bioceramic was investigated via the microbiological method.The model of rats'contaminated bone defect were deployed to study the antimicrobial performance of the bioceramic. Results The best synthesis condition was chosen at:0.1g calcium phosphate cements and 10.4 mg ceftriaxone sodium combined with 2.4 ml hardening liquid C.then keeping the mixture at 60℃ and 100%humidity for 24 h.In vitro release of the resulting antimicrobial bioceramic remained stable,while that of ceftriaxone sodium lasted for a week,higher than the minimal inhibitory concentration(MIC) of Staphylococcus aureus.As proved by the WBC number and tissue sectioning,a lighter inflammatory response of treatment group was observed as compared with the control group. Conclusion The antimicrobial bioceramic combined with chitosan and ceftriaxone sodium shows promising antimicrobial performance.%目的 使用壳聚糖和磷酸钙骨水泥(CPC)复合头孢曲松钠和BMP,制备出一种具有成骨和抗感染作用的植骨材料.方法 使用不同成分和比例的壳聚糖固化液将磷酸钙骨水泥、头孢曲松钠和BMP共混制备抗菌成骨生物陶瓷,绘制头孢曲松钠的紫外吸光度-浓度标准直线,测定生物陶瓷中头孢曲松钠体外释放浓度.微生物法测定生物陶瓷体外抑菌效果.生物陶瓷埋于大鼠腿部肌袋研究其成骨性能.将生物陶瓷填充大鼠污染骨缺损模型,研究其抑菌和成骨作用.结果 生物陶瓷的优化制备方案为0.1 g磷酸钙骨水泥复合10.4 mg头孢曲松钠和0.5 mg BMP与2

  18. Room-temperature formation of Pt$_3$Si/Pt$_2$Si films on poly-Si substrates

    CERN Document Server

    Dubkov, V P; Chizh, K V; Yuryev, V A

    2016-01-01

    We propose a way of formation of thin bilayer Pt$_3$Si/Pt$_2$Si films at room temperature on poly-Si substrates by Pt magnetron sputtering and wet etching, obtain such film, investigate its structure and phase composition and estimate the thickness of its layers. We verify by direct x-ray photoelectron-spectroscopic measurements our previous observation of the Pt$_2$Si layer formaton between Pt and poly-Si films as a result of Pt magnetron sputtering at room temperature. This layer likely appears due to high enough temperature of Pt ions in the magnetron plasma sufficient for chemical reaction of the silicide film formation on the Si surface. The Pt$_3$Si layer likely forms from the Pt--Pt$_3$Si layer (Pt$_{95}$Si$_5$), which arises under Pt film during the magnetron sputtering, as a result of Pt removal by wet etching.

  19. Analyses of the As doping of SiO{sub 2}/Si/SiO{sub 2} nanostructures

    Energy Technology Data Exchange (ETDEWEB)

    Ruffino, Francesco; Miritello, Maria [CNR-IMM MATIS, via S. Sofia 64, 95123 Catania (Italy); Tomasello, Mario Vincenzo [Scuola Superiore di Catania, via San Nullo 5/i, 95123 Catania (Italy); De Bastiani, Riccardo; Grimaldi, Maria Grazia [Dipartimento di Fisica ed Astronomia, Universita di Catania, via S. Sofia 64, 95123 Catania (Italy); CNR-IMM MATIS, via S. Sofia 64, 95123 Catania (Italy); Nicotra, Giuseppe; Spinella, Corrado [Consiglio Nazionale delle Ricerche-Istituto per la Microelettronica e Microsistemi (CNR-IMM), VIII Strada 5, 95121 Catania (Italy)

    2011-03-15

    We illustrate the behaviour of As when it is confined, by the implantation technique, in a SiO{sub 2}(70nm)/Si(30nm)/SiO{sub 2}(70nm) multilayer and its spatial redistribution when annealing processes are performed. By Rutherford backscattering spectrometry and Z-contrast transmission electron microscopy we found an As accumulation at the Si/SiO{sub 2} interfaces and at the Si grain boundaries with no segregation of the As in the Si layer. Such an effect is in agreement with a model that assumes a traps distribution in the Si in the first 2-3 nm above the SiO{sub 2}/Si interfaces and along the Si grain boundaries. The traps concentration at the Si/SiO{sub 2} interfaces was estimated in 10{sup 14} traps/cm{sup 2}. The outlined results can open perspectives on the doping properties of As in Si nanocrystals, whose applications in nanoelectronics and optoelectronics are widely investigated (copyright 2011 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  20. Thickness effect on the formation of SiC nanoparticles in sandwiched Si/C/Si and C/Si multilayers

    Energy Technology Data Exchange (ETDEWEB)

    Chung, C.K., E-mail: ckchung@mail.ncku.edu.t [Department of Mechanical Engineering, Center for Micro/Nano Science and Technology, National Cheng Kung University, Tainan, 701, Taiwan (China); Wu, B.H.; Chen, T.S.; Peng, C.C.; Lai, C.W. [Department of Mechanical Engineering, Center for Micro/Nano Science and Technology, National Cheng Kung University, Tainan, 701, Taiwan (China)

    2009-08-31

    The effect of carbon (C) and amorphous silicon (a-Si) thicknesses on the formation of SiC nanoparticles (np-SiC) in sandwiched Si/C/Si and C/Si multilayers on Si(100) substrates were investigated using ultra-high-vacuum ion beam sputtering system and vacuum thermal annealing at 500, 700, 900 {sup o}C for 1.0 h. Three-layer a-Si/C/a-Si structures with thicknesses of 50/200/50 nm and 75/150/75 nm and a two-layer C/a-Si structure of 200/50 nm were examined in this study. The size and density of np-SiC were strongly influenced by the annealing temperature, a-Si thickness and layer number. Many np-SiC appeared at 900 {sup o}C at a density order about 10{sup 8} cm{sup -2} in both three-layer structures while no particles formed in the two-layer structure. The thick a-Si structure (75/150/75 nm) produces a particle density approximately 1.8 times higher than thin structure (50/200/50 nm). This implies that thick a-Si structure had a lower activation energy of SiC formation compared to the thin a-Si structure. Few particles were found at 700 {sup o}C and no particles at 500 {sup o}C in both three-layer structures. The np-SiC formation is a thermally activated reaction. The higher temperature leads to higher particle density. A mechanism of np-SiC formation in thermodynamic and kinetic viewpoints is proposed.

  1. Mo-Si alloy development

    Energy Technology Data Exchange (ETDEWEB)

    Liu, C.T.; Heatherly, L.; Wright, J.L. [Oak Ridge National Lab., TN (United States)

    1996-06-01

    The objective of this task is to develop new-generation corrosion-resistant Mo-Si intermetallic alloys as hot components in advanced fossil energy conversion and combustion systems. The initial effort is devoted to Mo{sub 5}-Si{sub 3}-base (MSB) alloys containing boron additions. Three MSB alloys based on Mo-10.5Si-1.1B (wt %), weighing 1500 g were prepared by hot pressing of elemental and alloy powders at temperatures to 1600{degrees}C in vacuum. Microporosities and glassy-phase (probably silicate phases) formations are identified as the major concerns for preparation of MSB alloys by powder metallurgy. Suggestions are made to alleviate the problems of material processing.

  2. HV/CVD Grown Relaxed SiGe Buffer Layers for SiGe HMOSFETs

    Institute of Scientific and Technical Information of China (English)

    黄文韬; 罗广礼; 史进; 邓宁; 陈培毅; 钱佩信

    2003-01-01

    High-vacuum/chemical-vapor deposition (HV/CVD) system was used to grow relaxed SiGe buffer layers on Si substrates. Several methods were then used to analyze the quality of the SiGe films. X-ray diffraction and Raman spectroscopy showed that the upper layer was almost fully relaxed. Second ion mass spectroscopy showed that the Ge compositions were step-graded. Transmission electron microscopy showed that the misfit dislocations were restrained to the graded SiGe layers. Tests of the electrical properties of tensile-strained Si on relaxed SiGe buffer layers showed that their transconductances were higher than that of Si devices. These results verify the high quality of the relaxed SiGe buffer layer. The calculated critical layer thicknesses of the graded Si1-xGex layer on Si substrate and a Si layer on the relaxed SiGe buffer layer agree well with experimental results.

  3. High thermal conductivity SiC/SiC composites for fusion applications -- 2

    Energy Technology Data Exchange (ETDEWEB)

    Kowbel, W.; Tsou, K.T.; Withers, J.C. [MER Corp., Tucson, AZ (United States); Youngblood, G.E. [Pacific Northwest National Lab., Richland, WA (United States)

    1998-03-01

    This report covers material presented at the IEA/Jupiter Joint International Workshop on SiC/SiC Composites for Fusion Structural Applications held in conjunction with ICFRM-8, Sendai, Japan, Oct. 23--24, 1997. An unirradiated SiC/SiC composite made with MER-developed CVR SiC fiber and a hybrid PIP/CVI SiC matrix exhibited room temperature transverse thermal conductivity of 45 W/mK. An unirradiated SiC/SiC composite made from C/C composite totally CVR-converted to a SiC/SiC composite exhibited transverse thermal conductivity values of 75 and 35 W/mK at 25 and 1000 C, respectively. Both types of SiC/SiC composites exhibited non-brittle failure in flexure testing.

  4. Honda Civic Mugen Si Sedan

    Institute of Scientific and Technical Information of China (English)

    Prometheus

    2007-01-01

    美国本田汽车公司宣布08款本田Civic Mugen,SiSedan将于10月中旬正式亮相。这辆Civic Mugen Si Sedan配备有一个高性能的悬挂系统、锻造的铝质车轮、空气动力挠流体的设计式样和一个跑车化调校排气系统,新车搭载1998cc i-VTEC直四自然吸气引擎,

  5. Analysis of Si/SiGe Heterostructure Solar Cell

    Directory of Open Access Journals (Sweden)

    Ashish Kumar Singh

    2014-01-01

    Full Text Available Sunlight is the largest source of carbon-neutral energy. Large amount of energy, about 4.3 × 1020 J/hr (Lewis, 2005, is radiated because of nuclear fusion reaction by sun, but it is unfortunate that it is not exploited to its maximum level. Various photovoltaic researches are ongoing to find low cost, and highly efficient solar cell to fulfil looming energy crisis around the globe. Thin film solar cell along with enhanced absorption property will be the best, so combination of SiGe alloy is considered. The paper presented here consists of a numerical model of Si/Si1-xGex heterostructure solar cell. The research has investigated characteristics such as short circuit current density (Jsc, generation rate (G, absorption coefficient (α, and open circuit voltage (Voc with optimal Ge concentration. The addition of Ge content to Si layer will affect the property of material and can be calculated with the use of Vegard’s law. Due to this, short circuit current density increases.

  6. Progress of Si-based Optoelectronic Devices

    Institute of Scientific and Technical Information of China (English)

    PENG Ying-cai; FU Guang-sheng; WANG Ying-long; SHANG Yong

    2004-01-01

    Si-based optoelectronics is becoming a very active research area due to its potential applications to optical communications. One of the major goals of this study is to realize ali-Si optoelectronic integrated circuit. This is due to the fact that Si- based optoelectronic technology can be compatible with Si microelectronic technology. If Si-based optoelectronic devices and integrated circuits can be achieved,it will lead to a new informational technological revolution. In the article, the current developments of this exciting field are mainly reviewed in the recent years. The involved contents are the realization of various Si-based optoelectronic devices, such as light-emitting diodes,optical waveguides devices, Si photonic bandgap crystals,and Si laser,etc. Finally, the developed tendency of all-Si optoelectronic integrated technology are predicted in the near future.

  7. Laser annealing of sputter-deposited -SiC and -SiCN films

    Indian Academy of Sciences (India)

    M A Fraga; M Massi; I C Oliveira; F D Origo; W Miyakawa

    2011-12-01

    This work describes the laser annealing of -SiC and -SiCN films deposited on (100) Si and quartz substrates by RF magnetron sputtering. Two samples of -SiCN thin films were produced under different N2/Ar flow ratios. Rutherford backscattering spectroscopy (RBS), Raman analysis and Fourier transform infrared spectrometry (FTIR) techniques were used to investigate the composition and bonding structure of as-deposited and laser annealed SiC and SiCN films.

  8. Investigation of an a-Si/c-Si interface on a c-Si(P) substrate by simulation

    Institute of Scientific and Technical Information of China (English)

    Wang Jianqiang; Gao Hua; Zhang Jian; Meng Fanying; Ye Qinghao

    2012-01-01

    We investigate the recombination mechanism in an a-Si/c-Si interface,and analyze the key factors that influence the interface passivation quality,such as Qs,δp/δn and Dit.The polarity of the dielectric film is very important to the illustration level dependent passivation quality; when nδn =pδp and the defect level Et equal to Ei (c-Si),the defect states are the most effective recombination center,AFORS-HET simulation and analysis indicate that emitter doping and a-Si/c-Si band offset modulation are effective in depleting or accumulating one charged carrier.Interface states (Dit) severely deteriorate Voc compared with Jsc for a-Si/c-Si HJ cell performance when Dit is over 1 × 1010 cm-2.eV-1.For a c-Si(P)/a-Si(P+) structure,ΦBSF in c-Si and Φo in a-Si have different performances in optimization contact resistance and c-Si(P)/a-Si(P+) interface recombination.

  9. Microwave joining of SiC

    Energy Technology Data Exchange (ETDEWEB)

    Silberglitt, R.; Ahmad, I.; Tian, Y.L. [FM Technologies, Inc., Fairfax, VA (United States)] [and others

    1997-04-01

    The purpose of this work is to optimize the properties of SiC-SiC joints made using microwave energy. The current focus is on identification of the most effective joining methods for scale-up to large tube assemblies, including joining using SiC produced in situ from chemical precursors. During FY 1996, a new microwave applicator was designed, fabricated and tested that provides the capability for vacuum baking of the specimens and insulation and for processing under inert environment. This applicator was used to join continuous fiber-reinforced (CFCC) SiC/SiC composites using a polymer precursor to form a SiC interlayer in situ.

  10. Three carbon pairs in Si

    Energy Technology Data Exchange (ETDEWEB)

    Docaj, A. [Physics Department, Texas Tech University, Lubbock, TX 79409-1051 (United States); Estreicher, S.K., E-mail: Stefan.Estreicher@ttu.edu [Physics Department, Texas Tech University, Lubbock, TX 79409-1051 (United States)

    2012-08-01

    Carbon impurities in Si are common in floating-zone and cast-Si materials. The simplest and most discussed carbon complex is the interstitial-substitutional C{sub i}C{sub s} pair, which readily forms when self-interstitials are present in the material. This pair has three possible configurations, each of which is electrically active. The less common C{sub s}C{sub s} pair has been studied in irradiated material but has also recently been seen in as-grown C-rich cast-Si, which is commonly used to fabricate solar cells. The third pair consists of two interstitial C atoms: C{sub i}C{sub i}. Although its formation probability is low for several reasons, the C{sub i}C{sub i} pair is very stable and electrically inactive. In this contribution, we report preliminary results of first-principles calculations of these three C pairs in Si. The structures, binding energies, vibrational spectra, and electrical activity are predicted.

  11. Microscopic and macroscopic characterization of the charging effects in SiC/Si nanocrystals/SiC sandwiched structures.

    Science.gov (United States)

    Xu, Jie; Xu, Jun; Wang, Yuefei; Cao, Yunqing; Li, Wei; Yu, Linwei; Chen, Kunji

    2014-02-07

    Microscopic charge injection into the SiC/Si nanocrystals/SiC sandwiched structures through a biased conductive AFM tip is subsequently characterized by both electrostatic force microscopy and Kelvin probe force microscopy (KPFM). The charge injection and retention characteristics are found to be affected by not only the band offset at the Si nanocrystals/SiC interface but also the doping type of the Si substrate. On the other hand, capacitance-voltage (C-V) measurements investigate the macroscopic charging effect of the sandwiched structures with a thicker SiC capping layer, where the charges are injected from the Si substrates. The calculated macroscopic charging density is 3-4 times that of the microscopic one, and the possible reason is the underestimation of the microscopic charging density caused by the averaging effect and detection delay in the KPFM measurements.

  12. The impact resistance of SiC and other mechanical properties of SiC and Si3N4

    Science.gov (United States)

    Bradt, R. C.

    1984-01-01

    Studies focused on the impact and mechanical behavior of SiC and Si3N4 at high temperatures are summarized. Instrumented Charpy impact testing is analyzed by a compliance method and related to strength; slow crack growth is related to processing, and creep is discussed. The transient nature of flaw populations during oxidation under load is emphasized for both SiC and Si3N4.

  13. The HFIR 14J irradiation SiC/SiC composite and SiC fiber collaboration

    Energy Technology Data Exchange (ETDEWEB)

    Youngblood, G.E.; Jones, R.H. [Pacific Northwest National Lab., Richland, WA (United States); Kohyama, Akira; Katoh, Yutai [Kyoto Univ., Uji, Kyoto (Japan); Hasegawa, Akira [Tohoku Univ., Aramaki, Sendai (Japan); Snead, L. [Oak Ridge National Lab., TN (United States); Scholz, R.

    1998-09-01

    A short introduction with references establishes the current status of research and development of SiC{sub f}/SiC composites for fusion energy systems with respect to several key issues. The SiC fiber and composite specimen types selected for the JUPITER 14J irradiation experiment are presented together with the rationale for their selection.

  14. Effect of Ti and Si interlayer materials on the joining of SiC ceramics

    Energy Technology Data Exchange (ETDEWEB)

    Jung, Yang Il; Park, Jung Hwan; Kim, Hyun Gil; Park, Dong Jun; Park, Jeong Yong; Kim, Weon Ju [LWR Fuel Technology Division, Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of)

    2016-08-15

    SiC-based ceramic composites are currently being considered for use in fuel cladding tubes in light-water reactors. The joining of SiC ceramics in a hermetic seal is required for the development of ceramic-based fuel cladding tubes. In this study, SiC monoliths were diffusion bonded using a Ti foil interlayer and additional Si powder. In the joining process, a very low uniaxial pressure of ∼0.1 MPa was applied, so the process is applicable for joining thin-walled long tubes. The joining strength depended strongly on the type of SiC material. Reaction-bonded SiC (RB-SiC) showed a higher joining strength than sintered SiC because the diffusion reaction of Si was promoted in the former. The joining strength of sintered SiC was increased by the addition of Si at the Ti interlayer to play the role of the free Si in RB-SiC. The maximum joint strength obtained under torsional stress was ∼100 MPa. The joint interface consisted of TiSi{sub 2}, Ti{sub 3}SiC{sub 2}, and SiC phases formed by a diffusion reaction of Ti and Si.

  15. Effective passivation of Si surfaces by plasma deposited SiOx/a-SiNx:H stacks

    Science.gov (United States)

    Dingemans, G.; Mandoc, M. M.; Bordihn, S.; van de Sanden, M. C. M.; Kessels, W. M. M.

    2011-05-01

    Very low surface recombination velocities field-effect passivation was absent for a reference stack comprising thermally grown SiO2. The results indicate that hydrogenation of interface states played a key role in the passivation and remained effective up to annealing temperatures >800 °C.

  16. 口腔修复材料氧化锆生物陶瓷的制备方法及应用进展%Preparation of zirconia bioceramics and its application in prosthodontics

    Institute of Scientific and Technical Information of China (English)

    王强; 尹娇娇; 杨华哲

    2016-01-01

    背景:在众多口腔修复材料之中,氧化锆陶瓷具有高的强度、硬度和耐磨、耐腐蚀性等优良性能,然而远期临床观察中常出现基冠机械性能下降和饰瓷崩裂等稳定性问题,成为阻碍其进一步发展的瓶颈。  目的:归纳总结口腔修复氧化锆生物陶瓷材料的制备方法及应用进展。  方法:结合文献和课题组的研究,对氧化锆生物陶瓷的性质、晶体结构、制备方法及其在口腔修复领域应用的进展进行论述,指出影响其稳定性问题的原因,并对其发展方向做出预测。  结果与结论:氧化锆陶瓷的研制包括粉体合成、素坯成型、陶瓷烧结等几个方面。针对氧化锆基全瓷冠修复体的不稳定等问题,不仅需要从工艺上对氧化锆基粉体的制备进行优化,提高原料纯度、机械性能、生物性能和稳定性,而且需从晶体学角度研究晶体成核、生长、第二相及晶粒尺寸对晶体结构稳定性及基冠生物力学性能的影响,以及基冠与饰瓷晶格匹配对界面的影响等问题进行深入理论分析。%BACKGROUND:Zirconia is considered to be one ofthe promising prosthodontics materials because of its high strength, high hardness, excelent wear resistance and excelent corrosion resistance. However, the development of zirconia is hindered owing to the uncertainty in long-term stability of zirconiaal-ceramic crowns such as the cracking (chipping) of veneering porcelain and deterioration of mechanical properties of zirconia dental crowns under intraoral conditions. OBJECTIVE:To summarize the preparation of zirconia bioceramic and its application progress in the field of prosthodontics. METHODS:The properties, crystal structure, preparation and use of zirconia in prosthodontics were reviewed. Reasons that affected the stability of zirconia were also discussed. The future development of zirconia was forecasted. RESULTS AND CONCLUSION

  17. Niobium (V) doped bioceramics: evaluation of the hydrothermal route modified with citric acid and urea to obtain modified hydroxyapatite; Bioceramicas aditivadas com niobio (V): avaliacao da rota hidrotermica modificada com acido citrico e ureia para obtencao de hidroxiapatitas modificadas

    Energy Technology Data Exchange (ETDEWEB)

    Simomukay, E.; Souza, E.C.F. de; Antunes, S.R.M.; Borges, C.P.F.; Michel, M.D.; Antunes, A.C. [Universidade Estadual de Ponta Grossa (UEPG), Ponta Grossa, PR (Brazil)

    2016-01-15

    Synthetic hydroxyapatite (Ca{sub 10}(PO{sub 4}){sub 6}(OH){sub 2}; HA) has become a widely used ceramic material for bone reconstruction due to its biocompatibility with the bone tissue. This biocompatibility as well as other physical and chemical properties of the hydroxyapatite can be modified by the addition of different ions to its structure. Niobium (V) ion has not been commonly used in the hydroxyapatite synthesis. The objective of this study was to evaluate the use of hydrothermal route in the niobium (V) doped hydroxyapatite synthesis. The route used the niobium ammonium oxalate (NH{sub 4}H{sub 2}[NbO(C{sub 2}O{sub 4}){sub 3}].3H{sub 2}O) complex as a niobium (V) ion precursor. The addition of citric acid and urea in the hydrothermal route is used for the control of synthesis pH and precipitation rate. Pure sample and sample added with 5.3 ppm of niobium (V) ion were prepared. The coexistence of other phases besides the hydroxyapatite was not observed in any of the samples through the use of X-ray diffraction and infrared spectroscopy (FTIR) techniques. The FTIR technique revealed the presence of hydroxyapatite characteristic functional groups. The scanning electron microscopy analysis showed the formation of agglomerates composed of round particles, confirmed by the transmission electron microscopy technique. The X-ray fluorescence spectroscopic analysis detected the presence of niobium in the doped sample. The results showed that niobium (V) doped hydroxyapatite can be synthesized by means of hydrothermal route, which may be considered as huge potential for future application in bioceramics. (author)

  18. Study on the Properties of Fluorine Doped β-Calcium Polyphosphate Porous Bioceramics%氟掺杂β-聚磷酸钙多孔生物陶瓷特性研究

    Institute of Scientific and Technical Information of China (English)

    艾佳楠; 张垠; 王坤; 徐哲哲; 李文惠

    2013-01-01

    The amorphous and beta crystalline form of calcium polyphosphate (CPP) powder were fabricated by solid-state reaction method,porous calcium polyphosphate bioceramics prepared by impregnation with organic foam polyurethane foam as a template.In this study,using ammonium fluoride as introducing agent to introduce fluorine ion,by adjusting the amount of dilferent doping,investigating the influence of fluoride ion on the physical properties of the porous body,such as flexural strength,porosity,morphology,etc.The study shows that the introduction of ammonium fluoride can be significantly changing the β-CPP slurry' s viscosity and rheology,and to promote the sintering of the porous body to reduce porosity,and to make it more compact,and to improve the strength of the porous body.%采用固相烧结法制备了无定形和β晶型的聚磷酸钙(CPP)粉体,以β-CPP为基础粉料掺入氟化铵,并以聚氨酯泡沫为模板,采用有机泡沫浸渍法制备了掺氟多孔β-CPP生物陶瓷.本研究以氟化铵为导入剂引进氟离子,通过调节不同的掺杂量,研究了氟离子对多孔体物理性能的影响,如抗折强度、气孔率、微观形貌等.研究表明,氟化铵的引入可以显著地改变β-CPP浆料粘度和流变性,并促进多孔体的烧结,降低气孔率,使其更加致密化,提高多孔体强度.

  19. An introduction to the New SI

    CERN Document Server

    Knotts, Sandra; Phillips, William D

    2015-01-01

    Plans are underway to redefine the International System of Units (SI) around 2018. The New SI specifies the values of certain physical constants to define units. This article explains the New SI in a way that could be used to present it to high-school physics classes.

  20. Microwave joining of SiC

    Energy Technology Data Exchange (ETDEWEB)

    Silberglitt, R.; Ahmad, I. [FM Technologies, Inc., Fairfax, VA (United States); Black, W.M. [George Mason Univ., Fairfax, VA (United States)] [and others

    1995-05-01

    The purpose of this work is to optimize the properties of SiC-SiC joints made using microwave energy. The current focus is on optimization of time-temperature profiles, production of SiC from chemical precursors, and design of new applicators for joining of long tubes.

  1. 五种多孔生物陶瓷支架的肌肉植入实验研究%In vivo study of five porous bioceramic scaffolds implanted in animal muscle

    Institute of Scientific and Technical Information of China (English)

    许宋锋; 王臻; 于秀淳; 王林; 林开利; 常江

    2012-01-01

    目的 观察多孔生物玻璃(Bioglass)、β-磷酸三钙(β-tricalcium phosphate,β-TCP)、羟基磷灰石(hydroxyapatite,HA)、β-硅酸钙(β-calcium silicate,β-CS)、α-硅酸钙(α-CS)五种生物陶瓷支架植入家兔肌肉的生物学表现.方法 应用添加造孔剂工艺烧结制备得到多孔Bioglass、β-TCP、HA、β-CS 和α-CS支架,通过X线衍射、孔隙率测定、生物力学测定进行特征分析.将五种支架植入家兔背部肌肉中,4、8、12、16周取材,通过X线、Micro-CT、组织学、扫描电镜和能谱分析进行观察分析,并取材与支架接触肌肉进行聚合酶链式反应(polymerase chain reaction,PCR)分析骨形态发生蛋白-2 (bone morpho-genetic protein-2,BMP-2)和BMP-7含量.结果 五种支架特征分析表明,抗压强度:Bioglass>α-CS>β-CS>β-TCP>HA;弹性模量:α-CS<β-TCP<HA<ββ-CS<Bioglass;降解性:β-CS>α-CS>β-TCP> Bioglass> HA.组织学观察五种支架中均未出现新生骨组织.Bioglass、α-CS、β-CS表面有钙磷层形成,说明具有体内生物活性.16周时,只有β-CS出现BMP-2和BMP-7表达.结论 多孔硅酸钙支架具有良好体内生物活性、可降解性,但无体内骨诱导性.%Objective To investigate the in vivo biological performance of 5 porous bioceramic scaffolds,which were bioglass,β-tricalcium phosphate (β-TCP),hydroxyapatite (HA),β-calcium silicate (β-CS) and α-CS,implanted in rabbit dorsal muscle.Methods The 5 porous bioceramic scaffolds were fabricated by adding pore-forming materials and sintering,and then were investigated by X-ray diffraction,porosity mensuration and biomechanics test.The scaffolds were implanted into rabbit dorsal muscle for 4,8,12,16 weeks,respectively.The samples were analyzed by X-ray,Micro-CT,histological analysis,scanning electron microscope (SEM) and energy dispersive spectrometer (EDS).The expression of bone morphogenetic protein (BMP-2) and BMP-7 in the muscle in touch with bioceramic

  2. 3C-SiC nanocrystal growth on 10° miscut Si(001) surface

    Energy Technology Data Exchange (ETDEWEB)

    Deokar, Geetanjali, E-mail: gitudeo@gmail.com [INSP, UPMC, CNRS UMR 7588, 4 place Jussieu, Paris F-75005 (France); D' Angelo, Marie; Demaille, Dominique [INSP, UPMC, CNRS UMR 7588, 4 place Jussieu, Paris F-75005 (France); Cavellin, Catherine Deville [INSP, UPMC, CNRS UMR 7588, 4 place Jussieu, Paris F-75005 (France); Faculté des Sciences et Technologie UPEC, 61 av. De Gaulle, Créteil F-94010 (France)

    2014-04-01

    The growth of 3C-SiC nano-crystal (NC) on 10° miscut Si(001) substrate by CO{sub 2} thermal treatment is investigated by scanning and high resolution transmission electron microscopies. The vicinal Si(001) surface was thermally oxidized prior to the annealing at 1100 °C under CO{sub 2} atmosphere. The influence of the atomic steps at the vicinal SiO{sub 2}/Si interface on the SiC NC growth is studied by comparison with the results obtained for fundamental Si(001) substrates in the same conditions. For Si miscut substrate, a substantial enhancement in the density of the SiC NCs and a tendency of preferential alignment of them along the atomic step edges is observed. The SiC/Si interface is abrupt, without any steps and epitaxial growth with full relaxation of 3C-SiC occurs by domain matching epitaxy. The CO{sub 2} pressure and annealing time effect on NC growth is analyzed. The as-prepared SiC NCs can be engineered further for potential application in optoelectronic devices and/or as a seed for homoepitaxial SiC or heteroepitaxial GaN film growth. - Highlights: • Synthesis of 3C-SiC nanocrystals epitaxied on miscut-Si using a simple technique • Evidence of domain matching epitaxy at the SiC/Si interface • SiC growth proceeds along the (001) plane of host Si. • Substantial enhancement of the SiC nanocrystal density due to the miscut • Effect of the process parameters (CO{sub 2} pressure and annealing duration)

  3. Ultrasound assisted siRNA delivery using PEG-siPlex loaded microbubbles.

    Science.gov (United States)

    Vandenbroucke, Roosmarijn E; Lentacker, Ine; Demeester, Joseph; De Smedt, Stefaan C; Sanders, Niek N

    2008-03-20

    Short interfering RNA (siRNA) attracts much attention for the treatment of various diseases. However, its delivery, especially via systemic routes, remains a challenge. Indeed, naked siRNAs are rapidly degraded, while complexed siRNAs massively aggregate in the blood or are captured by macrophages. Although this can be circumvented by PEGylation, we found that PEGylation had a strong negative effect on the gene silencing efficiency of siRNA-liposome complexes (siPlexes). Recently, ultrasound combined with microbubbles has been used to deliver naked siRNA but the gene silencing efficiency is rather low and very high amounts of siRNA are required. To overcome the negative effects of PEGylation and to enhance the efficiency of ultrasound assisted siRNA delivery, we coupled PEGylated siPlexes (PEG-siPlexes) to microbubbles. Ultrasound radiation of these microbubbles resulted in massive release of unaltered PEG-siPlexes. Interestingly, PEG-siPlexes loaded on microbubbles were able to enter cells after exposure to ultrasound, in contrast to free PEG-siPlexes, which were not able to enter cells rapidly. Furthermore, these PEG-siPlex loaded microbubbles induced, in the presence of ultrasound, much higher gene silencing than free PEG-siPlexes. Additionally, the PEG-siPlex loaded microbubbles only silenced the expression of genes in the presence of ultrasound, which allows space and time controlled gene silencing.

  4. SiO adsorption on a p(2 × 2) reconstructed Si(1 0 0) surface

    NARCIS (Netherlands)

    Violanda, M.; Rudolph, H.

    2009-01-01

    We have investigated the adsorption mechanism of SiO molecule incident on a clean Si(1 0 0) p(2 × 2) reconstructed surface using density functional theory based methods. Stable adsorption geometries of SiO on Si surface, as well as their corresponding activation and adsorption energies are identifie

  5. Microstructure and wear studies of laser clad Al-Si/SiC(p) composite coatings

    NARCIS (Netherlands)

    Anandkumar, R.; Almeida, A.; Colaco, R.; Vilar, R.; Ocelik, V.; De Hosson, J. Th. M.

    2007-01-01

    Coatings of a composite material consisting of an Al-Si matrix reinforced with SiC particles were produced by laser cladding on UNS A03560 cast Al-alloy substrates from mixtures of powders of Al-12 wt.% Si alloy and SiC. The influence of the processing parameters on the microstructure and abrasive w

  6. Laser cladding of Al-Si/SiC composite coatings : Microstructure and abrasive wear behavior

    NARCIS (Netherlands)

    Anandkumar, R.; Almeida, A.; Vilar, R.; Ocelik, V.; De Hosson, J.Th.M.

    2007-01-01

    Surface coatings of an Al-Si-SiC composite were produced on UNS A03560 cast Al-alloy substrates by laser cladding using a mixture of powders of Al-12 wt.% Si alloy and SiC. The microstructure of the coatings depends considerably on the processing parameters. For a specific energy of 26 MJ/m2 the mic

  7. MoSi2 oxidation resistance coatings for Mo5Si3/MoSi2 composites

    Institute of Scientific and Technical Information of China (English)

    YAN Jianhui; XU Hongmei; ZHANG Houan; TANG Siwen

    2009-01-01

    In order to improve the oxidation resistance properties of 30 at.% Mo5Si3/MoSi2 composite at high temperature in air, a molybdenum disili-tide coating was prepared on its surface by a molten salt technology. XRD and SEM analysis showed that only tetragonal MoSi2 phase ex-isted in the coating after being siliconized for 5 h at 900℃. The oxidation film formed on the uncoated sample was not dense, so that oxygen diffused easily through it. The volatilization of MoO3 resulted in the oxidation film separating from the substrate. The MoSi2coating was proved to be an effective method to prevent 30 at.% MosSi3/MoSi2 composites from being oxidized at 1200℃. A dense glassy SiO2 film was formed on the MoSi2 coating surface, which acted as a barrier layer for the diffusion of oxygen atoms to the substrate. The 30at.% Mo5Si3/MoSi2 composites with a MoSi2 coating showed much better oxidation resistance at high temperature.

  8. In vitro prominent bone regeneration by release zinc ion from Zn-modified implant

    Energy Technology Data Exchange (ETDEWEB)

    Yusa, Kazuyuki [Department of Biochemistry, Akita University Graduate School of Medicine, Akita (Japan); Yamamoto, Osamu [Department of Bio-System Engineering, Graduate School of Science and Engineering, Yamagata University, Yonezawa (Japan); Fukuda, Masayuki [Division of Dentistry and Oral Surgery, Akita University Hospital, Akita (Japan); Koyota, Souichi; Koizumi, Yukio [Department of Biochemistry, Akita University Graduate School of Medicine, Akita (Japan); Sugiyama, Toshihiro, E-mail: sugiyama@med.akita-u.ac.jp [Department of Biochemistry, Akita University Graduate School of Medicine, Akita (Japan)

    2011-08-26

    Highlights: {yields} We isolated the Zn{sup 2+} ions (eluted Zn{sup 2+} ion; EZ) from zinc-incorporated titanium implant. {yields} The EZ promoted the cell viability in hBMCs. {yields} The EZ stimulated preosteoblast and osteoblast marker gene expression in hBMCs. {yields} The hBMCs supplemented with EZ showed typically cell morphology when osteoblast maturing. {yields} It is revealed that the EZ also stimulates the calcium deposition of hBMCs. -- Abstract: Zinc is one of the trace elements which induce the proliferation and the differentiation of the osteoblast. In the previous study, we found that zinc ions (Zn{sup 2+} ion)-releasing titanium implants had excellent bone fixation using a rabbit femurs model. In this study, we isolated the Zn{sup 2+} ions (eluted Zn{sup 2+} ion; EZ) released from the implant surface, and evaluated the effect of EZ on the osteogenesis of human bone marrow-derived mesenchymal cells (hBMCs). In the result, it was found that the EZ stimulated cell viability, osteoblast marker gene (type I collagen, osteocalcin (OC), alkaline phosphatase (ALP) and bone sialoprotein (BSP)) expressions and calcium deposition in hBMCs.

  9. Removing Trypan blue dye using nano-Zn modified Luffa sponge

    Science.gov (United States)

    Nadaroglu, Hayrunnisa; Cicek, Semra; Gungor, Azize Alayli

    2017-02-01

    This study has presented specific features that are examined to remove the Trypan blue dye from the waste using Luffa sponge (LS) and modified Luffa sponge with zinc nanoparticles (ZnNPs). Peroxidase enzyme was obtained from Euphorbia amygdaloides plant and it was used with the green synthesis of Zn nanoparticles. Luffa sponge was used to be a support material for immobilized nanoparticles and it also used in remediation work. The obtained membrane forms, fibrous materials, (LS, ZnNPs-LS) were characterized with SEM and XRD. LS and ZnNPs-LS were employed as adsorbent to be used for the removal of Trypan blue dye from aqueous via batch studies. Measurements were made for the equilibrium, pH, temperature, concentration of dye with UV-visible spectrometer (590 nm; for Trypan blue dye). The optimum removal of Trypan blue dye was found at pH 7, the equilibrium was attained within 30 min. The thermodynamic properties ΔG0, ΔH0, and ΔS0 showed that adsorption of Trypan blue dye onto LS and ZnNPs-LS were spontaneous and endothermic. The equilibrium isotherm data were analyzed using Langmuir and Freundlich models and the sorption process was described by the Langmuir isotherm with maximum monolayer adsorption capacity of 45.32 and 47.3 mg/g for LS and LS-ZnNPs at 303 ± 1 °K, respectively.

  10. Si Scott溜冰鞋

    Institute of Scientific and Technical Information of China (English)

    2010-01-01

    Vauxhall Ice Skate公司特别邀请Si Scott为Vauxhall Ice Skate event活动设计了一款造型奇特的溜冰鞋:鞋身以轿车模样出现下面则是冰刀,再加上设计师的非凡创意涂鸦,令溜冰鞋充满童趣。

  11. Nanoporosity of Si (100) bars

    Science.gov (United States)

    Novikov, S. N.; Timoshenkov, S. P.; Minaev, V. S.; Goryunova, E. P.; Gerasimenko, N. N.; Smirnov, D. I.

    2016-09-01

    Si(100) samples cut from a typical bar (100 mm in diameter) prepared using industrial technology are studied. Measurements of the electron work function (EWF) show that the size effects in these samples (a reduction in thickness along with a sample's area and the EWF) detected earlier were due to nanostructure porosity that was buried by the technological treatment of a bar's surface. This hidden nanoporosity is assumed to be a manifestation of the secondary crystal structure.

  12. Columnar growth of CoSi2 on Si(111), Si(100) and Si(110) by molecular beam epitaxy

    Science.gov (United States)

    Fathauer, R. W.; Nieh, C. W.; Xiao, Q. F.; Hashimoto, Shin

    1990-01-01

    Codeposition of silicon and cobalt on heated silicon substrates in ratios several times the silicide stoichiometry is found to result in epitaxial columns of CoSi2 surrounded by a matrix of epitaxial silicon. For (111)-oriented wafers, nearly cylindrical columns are formed, where both columns and surrounding silicon are defect free, as deduced from transmission electron microscopy. Independent control of the column diameter and separation is possible, and diameters of 27-135 nm have been demonstrated.

  13. Abrupt GaP/Si hetero-interface using bistepped Si buffer

    Energy Technology Data Exchange (ETDEWEB)

    Ping Wang, Y., E-mail: yanping.wang@insa-rennes.fr; Kuyyalil, J.; Nguyen Thanh, T.; Almosni, S.; Bernard, R.; Tremblay, R.; Da Silva, M.; Létoublon, A.; Rohel, T.; Tavernier, K.; Le Corre, A.; Cornet, C.; Durand, O. [UMR FOTON, CNRS, INSA Rennes, Rennes F-35708 (France); Stodolna, J.; Ponchet, A. [CEMES-CNRS, Université de Toulouse, 29 rue Jeanne Marvig, BP 94347, 31055 Toulouse Cedex 04 (France); Bahri, M.; Largeau, L.; Patriarche, G. [Laboratoire de Photonique et Nanostructures, CNRS UPR 20, Route de Nozay, Marcoussis 91460 (France); Magen, C. [LMA, INA-ARAID, and Departamento de Física de la Materia Condensada, Universidad de Zaragoza, 50018 Zaragoza (Spain)

    2015-11-09

    We evidence the influence of the quality of the starting Si surface on the III-V/Si interface abruptness and on the formation of defects during the growth of III-V/Si heterogeneous crystal, using high resolution transmission electron microscopy and scanning transmission electron microscopy. GaP layers were grown by molecular beam epitaxy on vicinal Si (001). The strong effect of the Si substrate chemical preparation is first demonstrated by studying structural properties of both Si homoepitaxial layer and GaP/Si heterostructure. It is then shown that choosing adequate chemical preparation conditions and subsequent III-V regrowth conditions enables the quasi-suppression of micro-twins in the epilayer. Finally, the abruptness of GaP/Si interface is found to be very sensitive to the Si chemical preparation and is improved by the use of a bistepped Si buffer prior to III-V overgrowth.

  14. The Effect of Different Nd2O3 Contents on Biocompatibility of Rare Earths Active Bioceramic Gradient Coating Produced by Wide-Band Laser Cladding%Nd2O3含量对宽带激光熔覆生物活性稀土梯度涂层生物相容性的影响

    Institute of Scientific and Technical Information of China (English)

    王永福; 王毅; 汪震

    2012-01-01

    In this paper, as to problem on bioceramic coating at present, a kind of gradient bioceramic coating is designed, the rare earths active gradient bioceramic coating with HA and β-TCP on TC4 titanium alloy was prepared by using wide-band laser cladding technique, the microstructure of gradient bioceramic coating was studied with the help of XRD、SEM. The method was to culture osteoblast on gradient bioceramic coating in vitro. Nd2O3 plays an important role in inducing to synthesize HA and β-TCP during laser cladding . When the content of Nd2O3 reaches to 0.6wt.%, the amount of synthesizing HA and β-TCP is the most; At the same time, Nd2O3 plays an important role to Coating morpholgies; the coating containing Nd2O3 has no toxic effect.%针对目前生物活性陶瓷涂层存在的问题,设计了一种梯度涂层,采用宽带激光熔覆技术,通过加入不同含量的稀土氧化物Nd2O3来提高激光熔覆生物陶瓷涂层的生物相容性,在Ti-6Al-4V合金表面制备了含HA+β-TCP的稀土活性梯度陶瓷涂层.利用SEM、XRD对活性涂层组织结构进行了研究.采用体外人成骨细胞与材料共培养的方法,对梯度活性陶瓷涂层进行了细胞形态实验.结果表明:Nd2O3含量的不同,对涂层催化效果不一样,使得复合涂层呈现形态各异的表面特征,但涂层表面都具有一定的粗糙度,将增加生物陶瓷涂层与骨组织的生物相容性;稀土氧化物Nd2O3在激光熔覆生物陶瓷过程中具有催化合成HA+β-TCP的作用,当w(Nd2O3)=0.6%时,诱导合成HA+β-TCP的数量最多;含稀土氧化物Nd2O3的涂层对成骨细胞无毒副作用,当w(Nd2O3=0.6%时染色呈正常梭形状态的细胞数目最多,具有最佳的生物相容性.

  15. Lattice dislocation in Si nanowires

    Energy Technology Data Exchange (ETDEWEB)

    Omar, M.S., E-mail: dr_m_s_omar@yahoo.co [Department of Physics, College of Science, University of Salahaddin, Arbil, Iraqi Kurdistan (Iraq); Taha, H.T. [Department of Physics, College of Science, University of Salahaddin, Arbil, Iraqi Kurdistan (Iraq)

    2009-12-15

    Modified formulas were used to calculate lattice thermal expansion, specific heat and Bulk modulus for Si nanowires with diameters of 115, 56, 37 and 22 nm. From these values and Gruneisen parameter taken from reference, mean lattice volumes were found to be as 20.03 A{sup 3} for the bulk and 23.63, 29.91, 34.69 and 40.46 A{sup 3} for Si nanowire diameters mentioned above, respectively. Their mean bonding length was calculated to be as 0.235 nm for the bulk and 0.248, 0.269, 0.282 and 0.297 nm for the nanowires diameter mentioned above, respectively. By dividing the nanowires diameter on the mean bonding length, number of layers per each nanowire size was found to be as 230, 104, 65 and 37 for the diameters mentioned above, respectively. Lattice dislocations in 22 nm diameter wire were found to be from 0.00324 nm for the 1st central lattice to 0.2579 nm for the last surface lattice. Such dislocation was smaller for larger wire diameters. Dislocation concentration found to change in Si nanowires according to the proportionalities of surface thickness to nanowire radius ratios.

  16. Effect of Si interface surface roughness to the tunneling current of the Si/Si{sub 1-x}Ge{sub x}/Si heterojunction bipolar transistor

    Energy Technology Data Exchange (ETDEWEB)

    Hasanah, Lilik, E-mail: lilikhasanah@upi.edu; Suhendi, Endi; Tayubi, Yuyu Rahmat; Yuwono, Heru [Department of Physics Education, Universitas Pendidikan Indonesia, Jl. Setiabudhi 229 Bandung 40154 (Indonesia); Nandiyanto, Asep Bayu Dani [Department Kimia, Universitas Pendidikan Indonesia, Jl. Setiabudhi 229 Bandung 40154 (Indonesia); Murakami, Hideki [Graduate School of Advanced Sciences of Matter, Hiroshima University, Higashi-Hiroshima 739-8527 (Japan); Khairrurijal [Physics of Electronic Materials Research Division, Institut Teknologi Bandung, Bandung 40132 (Indonesia)

    2016-02-08

    In this work we discuss the surface roughness of Si interface impact to the tunneling current of the Si/Si{sub 1-x}Ge{sub x}/Si heterojunction bipolar transistor. The Si interface surface roughness can be analyzed from electrical characteristics through the transversal electron velocity obtained as fitting parameter factor. The results showed that surface roughness increase as Ge content of virtual substrate increase This model can be used to investigate the effect of Ge content of the virtual substrate to the interface surface condition through current-voltage characteristic.

  17. Active Oxidation of SiC

    Science.gov (United States)

    Jacobson, Nathan S.; Myers,Dwight L.; Harder, Bryan J.

    2011-01-01

    The high temperature oxidation of silicon carbide occurs in either a passive or active mode, depending on temperature and oxygen potential. Passive oxidation forms a protective oxide film which limits attack of the SiC:SiC(s) + 3/2 O2(g) = SiO2(s) + CO(g.) Active oxidation forms a volatile oxide and leads to extensive attack of the SiC: SiC(s) + O2(g) = SiO(g) + CO(g). The transition points and rates of active oxidation are a major issue. Previous studies are reviewed and the leading theories of passive/active transitions summarized. Comparisons are made to the active/passive transitions in pure Si, which are relatively well-understood. Critical questions remain about the difference between the active-to-passive transition and passive-to-active transition. For Si, Wagner [2] points out that the active-to-passive transition is governed by the criterion for a stable Si/SiO2 equilibria and the passive-to-active transition is governed by the decomposition of the SiO2 film. This suggests a significant oxygen potential difference between these two transitions and our experiments confirm this. For Si, the initial stages of active oxidation are characterized by the formation of SiO(g) and further oxidation to SiO2(s) as micron-sized rods, with a distinctive morphology. SiC shows significant differences. The active-to-passive and the passive-to-active transitions are close. The SiO2 rods only appear as the passive film breaks down. These differences are explained in terms of the reactions at the SiC/SiO2 interface. In order to understand the breakdown of the passive film, pre-oxidation experiments are conducted. These involve forming dense protective scales of 0.5, 1, and 2 microns and then subjecting the samples with these scales to a known active oxidation environment. Microstructural studies show that SiC/SiO2 interfacial reactions lead to a breakdown of the scale with a distinct morphology.

  18. Current–voltage studies on -FeSi2/Si heterojunction

    Indian Academy of Sciences (India)

    A Datta; S Kal; S Basu

    2000-08-01

    – characteristics of both -FeSi2/n-Si and -FeSi2/p-Si were studied at room temperature. The junctions were formed by depositing Fe on Si selectively followed by thermal annealing and some samples were later treated by pulsed laser. Temperature of thermal annealing and diode area were also varied. – studies on all these samples were done and ideality factors were computed. Results obtained were interpreted.

  19. Complexation of Si in Hydrothermal Systems

    Institute of Scientific and Technical Information of China (English)

    樊文苓; 王声远; 田弋夫; 陈紫新

    2001-01-01

    The Au-SiO2 and Sn-SiO2 complexes have been experimentally calibrated at varying temperature, silica concentration and pH:Au+ + H3SiO4-=AuH3SiO4 lgK = - 1. 65436 + 9611.21/TSn4 + + 4H3SiO4-=Sn(H3SiO4)4 lgK200℃ = 42.73Compared with Au-Cl, Au-HS and Sn-OH complexes, AuH3SiO4 and Sn(H3SiO4)4 complexes can be recognized as the dominant transport forms in Si-bearing solutions under pH and Eh con ditions of general interest. The decrease of SiO2 concentration and oxygen fugacity would re verse the direction of dissolution-complexing reactions, resulting in the precipitation of gold and silica, as well as cassiterite and silica. This study illustrates the significance of SiO2-complexa tion in hydrothermal solutions for gold, tin and other metallizations.

  20. Comparison of the thermal stabilities of NiSi films in Ni/Si, Ni/Pd/Si and Ni/Pt/Si systems

    CERN Document Server

    Wang, R N

    2003-01-01

    The effects of different interlayer materials (Pd and Pt) deposited between Ni films and Si substrates on the NiSi thermal stability are discussed. Ni sub 0 sub . sub 9 sub 4 sub 3 Pd sub 0 sub . sub 0 sub 5 sub 7 Si and Ni sub 0 sub . sub 9 sub 4 sub 5 Pt sub 0 sub . sub 0 sub 5 sub 5 Si solid solutions were formed when the samples were annealed at high temperatures and the lattice parameters of Ni sub 0 sub . sub 9 sub 4 sub 3 Pd sub 0 sub . sub 0 sub 5 sub 7 Si were calculated according to Vegard's law. The NiSi thermal stability was enhanced by interposing a Pd or Pt interlayer, and the sample with the Pt interlayer had the highest NiSi thermal stability among all the samples studied. This is attributed to the reduction of the interface energy between NiSi and Si substrates and the decrease of the driving force for the nucleation of NiSi sub 2 , induced by formation of the NiSi(200) preferred orientation and the solid solution respectively.

  1. Hierarchical Cd4SiS6/SiO2 Heterostructure Nanowire Arrays

    Directory of Open Access Journals (Sweden)

    Liu Jian

    2009-01-01

    Full Text Available Abstract Novel hierarchical Cd4SiS6/SiO2 based heterostructure nanowire arrays were fabricated on silicon substrates by a one-step thermal evaporation of CdS powder. The as-grown products were characterized using scanning electron microscopy, X-ray diffraction, and transmission electron microscopy. Studies reveal that a typical hierarchical Cd4SiS6/SiO2 heterostructure nanowire is composed of a single crystalline Cd4SiS6 nanowire core sheathed with amorphous SiO2 sheath. Furthermore, secondary nanostructures of SiO2 nanowires are highly dense grown on the primary Cd4SiS6 core-SiO2 sheath nanowires and formed hierarchical Cd4SiS6/SiO2 based heterostructure nanowire arrays which stand vertically on silicon substrates. The possible growth mechanism of hierarchical Cd4SiS6/SiO2 heterostructure nanowire arrays is proposed. The optical properties of hierarchical Cd4SiS6/SiO2 heterostructure nanowire arrays are investigated using Raman and Photoluminescence spectroscopy.

  2. Differential cross sections measurement of 28Si(p,p/γ)28Si and 29Si(p,p/γ)29Si reactions for PIGE applications

    Science.gov (United States)

    Jokar, A.; Kakuee, O.; Lamehi-Rachti, M.

    2016-03-01

    Differential cross sections for gamma-ray emission from the 28Si(p,p/γ)28Si (Eγ = 1779 keV) and the 29Si(p,p/γ)29Si (Eγ = 1273 keV) nuclear reactions were measured in the energy range of 2.0-3.2 MeV and 2.0-3.0 MeV, respectively. The thin Si targets were prepared by evaporating natural SiO onto self-supporting Ag films. The gamma-rays and backscattered protons were detected simultaneously. An HPGe detector placed at an angle of 90° with respect to beam direction was employed to collect gamma-rays while an ion implanted Si detector placed at a scattering angle of 165° was used to detect backscattered protons. The great advantage of this work is that differential cross sections were obtained with a procedure irrespective of absolute value of the collected beam charge.

  3. Theoretic Study on Band Structure of Si/SiNx Multilayer Film%Si/SiNx多层膜能带结构的理论研究

    Institute of Scientific and Technical Information of China (English)

    徐明; 魏屹; 何贤模; 芦伟

    2010-01-01

    利用Kronig-Penney模型计算了Si/SiNx多层膜结构中Si亚层的能带结构.结果表明,无论是减少Si或Si/SiNx亚层的厚度都将导致Si层的带隙发生宽化,计算结果与实验值符合较好.进而还发现,当Si层厚度减小时,Si/SiNx多层膜结构中载流子(电子和空穴)的有效质量均减小,有利于对载流子复合发光的控制.计算结果对实验上研究发光可控的Si/SiNx多层膜结构有重要指导意义.

  4. Deformation effects in the 28Si + 12C and 28Si + 28Si reactions

    Indian Academy of Sciences (India)

    C Bhattacharya; M Rousseau; C Beck; V Rauch; R M Freeman; R Nouicer; F Haas; O Dorvaux; K Eddahbi; P Papka; O Stezwski; S Szilner; D Mahboub; A Szanto De Toledo; A Hachem; E Martin; S J Sanders

    2001-07-01

    The possible occurrence of highly deformed configurations is investigated in the 40Ca and 56Ni di-nuclear systems as formed in the 28Si + 12C, 28Si reactions by using the properties of emitted light charged particles. Inclusive as well as exclusive data of the heavy fragments and their associated light charged particles have been collected by using the ICARE charged particle multidetector array. The data are analysed by Monte Carlo CASCADE statistical-model calculations using a consistent set of parameters with spin-dependent level densities. Significant deformation effects at high spin are observed as well as an unexpected large 8Be cluster emission of a binary nature.

  5. WET SYNTHESIS AND STRUCTURAL CHARACTERIZATION OF BIO-CERAMICS WITH SILICON-SUBSTITUTED HYDROXYAPATITE%含硅羟基磷灰石生物陶瓷的湿法合成及结构特征

    Institute of Scientific and Technical Information of China (English)

    肖凤娟; 常虹; 韩玉芳; 庞敏

    2007-01-01

    The incorporation of silicon into the hydroxyapatite (HA) lattice can improve the bioactivity of HA. Silicon-substituted HAs (Si-HA) have been prepared by incorporating a small amount of silicon into a HA lattice via an aqueous precipitation reaction.The crystalline phase, microstructure, chemical composition and morphology of the Si-HA and the interaction between Si-HA and BSA were characterized by X-ray fluorescence spectroscopy, X-ray diffraction and fluorescence. The results show that the proposed substitution of the silicon (or silicate) ions for the phosphorus (or phosphate) ion in the HA. Analysis of the Si-HA by Fourier transform infrared spectroscopy (FTIR) indicates that the silicon substitution affect the FTIR of the HA in the P-O and O-H vibrational bands, and the intensity of the absorption peak of the O-H and P-O in the Si-HA is lower than that in the HA. The intensity of the absorption peak of PO43- in the Si-HA decreases, and the fluorescence intensity in the BSA is quenched. With the substitution of SiO44- for PO43-, and the absorption peak of the amide group (-CONH2) in BSA is observed in the silicon-substituted HA substrate by FTIR. It is suggested that the Si-HA-BSA complexes have been formed by positive Ca2+ in Si-HA binding negative -COOH- in the BSA and SiO44-, and the PO43- in the Si-HA binding to -NH2 in the BSA. On the basis of these results, the better bioactivity mechanism of Si-HA than that of HA is discussed.%将硅(Si)掺入羟基磷灰石(hydroxyapatite,HA)的晶格中能有效提高HA的生物活性.用湿法合成了含硅的羟基磷灰石微粉(Si-HA).用X射线荧光光谱、X射线衍射、红外光谱(Fourier transform infrared spectroscopy,FTIR)、扫描电镜和荧光光谱等对Si-HA的晶相、结构、化学组成、形貌及其与牛血清白蛋白(Bovine serum albumin,BSA)的相互作用进行了表征和分析.结果表明:Si元素溶入HA晶格中,使HA晶胞参数和结构发生变化.

  6. Corrosion properties of amorphous Mo-Si-N and nanolayered Mo-Si-Nn/SiC coatings

    Energy Technology Data Exchange (ETDEWEB)

    Torri, P.; Mahiout, A.; Koskinen, J.; Hirvonen, J.P.; Johansson, L.S.

    2000-02-01

    Corrosion properties of sputter deposited MoSi{sub 2}, SiC, Mo-Si-N (MoSi{sub 2.2}N{sub 2.5}) and nanolayered Mo-Si-N/SiC coatings on Fe37 low carbon steel have been studied using electrochemical polarization measurements in 1 N H{sub 2}SO{sub 4} solution. A decrease in both critical current density for passivation and minimum current in passive state was observed in annealed nanolayered Mo-Si-N/SiC coating compared to each of its constituents alone as single layer coating. On contrary to MoSi{sub 2} coating, only slight increase in critical current density was observed in Mo-Si-N coated sample after annealing. Molybdenum disilicide source material has good thermal and electrical conductivity, which allows effective dc-magnetron sputter deposition. Therefore this is a relatively simple method to produce amorphous coatings which have a high crystallization temperature and promising properties for corrosion applications.

  7. Fiber/matrix interfaces for SiC/SiC composites: Multilayer SiC coatings

    Energy Technology Data Exchange (ETDEWEB)

    Halverson, H.; Curtin, W.A. [Virginia Polytechnic Institute and State Univ., Blacksburg, VA (United States)

    1996-08-01

    Tensile tests have been performed on composites of CVI SiC matrix reinforced with 2-d Nicalon fiber cloth, with either pyrolitic carbon or multilayer CVD SiC coatings [Hypertherm High-Temperature Composites Inc., Huntington Beach, CA.] on the fibers. To investigate the role played by the different interfaces, several types of measurements are made on each sample: (i) unload-reload hysteresis loops, and (ii) acoustic emission. The pyrolitic carbon and multilayer SiC coated materials are remarkably similar in overall mechanical responses. These results demonstrate that low-modulus, or compliant, interface coatings are not necessary for good composite performance, and that complex, hierarchical coating structures may possibly yield enhanced high-temperature performance. Analysis of the unload/reload hysteresis loops also indicates that the usual {open_quotes}proportional limit{close_quotes} stress is actually slightly below the stress at which the 0{degrees} load-bearing fibers/matrix interfaces slide and are exposed to atmosphere.

  8. Preparation of the fast setting and degrading Ca-Si-Mg cement with both odontogenesis and angiogenesis differentiation of human periodontal ligament cells.

    Science.gov (United States)

    Chen, Yi-Wen; Hsu, Tuan-Ti; Wang, Kan; Shie, Ming-You

    2016-03-01

    Develop a fast setting and controllable degrading magnesium-calcium silicate cement (Mg-CS) by sol-gel, and establish a mechanism using Mg ions to stimulate human periodontal ligament cells (hPDLs) are two purposes of this study. We have used the diametral tensile strength measurement to obtain the mechanical strength and stability of Mg-CS cement; in addition, the cement degradation properties is realized by measuring the releasing amount of Si and Mg ions in the simulated body fluid. The other cell characteristics of hPDLs, such as proliferation, differentiation and mineralization were examined while hPDLs were cultured on specimen surfaces. This study found out the degradation rate of Mg-CS cements depends on the Mg content in CS. Regarding in vitro bioactivity; the CS cements were covered with abundant clusters of apatite spherulites after immersion of 24h, while less apatite spherulites were formatted on the Mg-rich cement surfaces. In addition, the authors also explored the effects of Mg ions on the odontogenesis and angiogenesis differentiation of hPDLs in comparison with CS cement. The proliferation, alkaline phosphatase, odontogenesis-related genes (DSPP and DMP-1), and angiogenesis-related protein (vWF and ang-1) secretion of hPDLs were significantly stimulated when the Mg content of the specimen was increased. The results in this study suggest that Mg-CS materials with this modified composition could stimulate hPDLs behavior and can be good bioceramics for bone substitutes and hard tissue regeneration applications as they stimulate odontogenesis/angiogenesis.

  9. Synthesis, Characterization, In Vitro Bioactivity and Biocompatibility Evaluation of Hydroxyapatite/Bredigite (Ca7MgSi4O16) Composite Nanoparticles

    Science.gov (United States)

    Kouhi, Monireh; Shamanian, Morteza; Fathi, Mohammadhossein; Samadikuchaksaraei, Ali; Mehdipour, Ahmad

    2016-04-01

    Silicate-based bioceramics have been found to possess excellent apatite-forming ability, and they can stimulate cell proliferation and osteogenic differentiation. In this study, bredigite (Ca7MgSi4O16) nanoparticles were synthesized and incorporated into a hydroxyapatite (HA)-based matrix to produce composite nanoparticles with improved bioactivity and biocompatibility. HA/bredigite nanoparticles containing 25% and 50% bredigite were synthesized by using the sol-gel method. X-ray diffraction, transmission electron microscopy, scanning electron microscopy, energy-dispersive x-ray spectroscopy, and Fourier transform infrared techniques were used to study the phase structure, morphology, and structural properties of prepared nanoparticles. Results indicated that HA/bredigite nanoparticles with an average particle size of less than 50 nm and homogeneous distribution of bredigite were successfully synthesized. Obtained results also revealed that the presence of bredigite led to a small increase in HA lattice parameters and to a decrease in the agglomeration of composite nanoparticles. The in vitro bioactivity studies performed in the simulated body fluid showed that composite nanoparticles had higher apatite-forming ability than pure HA. The results of a cell proliferation assay revealed that the proliferation of mesenchymal stem cells in the extract of HA/bredigite was significantly higher than those in the extract of the initial HA and control group after 72 h. As the properties of HA/bredigite nanoparticles were highly improved, compared with pure HA, it is concluded that these composite nanoparticles could potentially be good candidates for use as effective bioactive materials in bone regeneration applications.

  10. High-efficiency si/polymer hybrid solar cells based on synergistic surface texturing of Si nanowires on pyramids.

    Science.gov (United States)

    He, Lining; Lai, Donny; Wang, Hao; Jiang, Changyun; Rusli

    2012-06-11

    An efficient Si/PEDOT:PSS hybrid solar cell using synergistic surface texturing of Si nanowires (SiNWs) on pyramids is demonstrated. A power conversion efficiency (PCE) of 9.9% is achieved from the cells using the SiNW/pyramid binary structure, which is much higher than similar cells based on planar Si, pyramid-textured Si, and SiNWs. The PCE is the highest reported to-date for hybrid cells based on Si nanostructures and PEDOT.

  11. Simulation analysis of the effects of a back surface field on a p-a-Si:H/n-c-Si/n+-a-Si:H heterojunction solar cell

    Institute of Scientific and Technical Information of China (English)

    Hu Yuehui; Zhang Xiangwen; Qu Minghao; Wang Lifu; Zeng Tao; Xie Yaojiang

    2009-01-01

    In order to investigate the effects of a back surface field (BSF) on the performance of a p-doped amorphous silicon (p-a-Si:H)/n-doped crystalline silicon (n-c-Si) solar cell, a heterojunction solar cell with a p-a-Si:H/nc-Si/n+-a-Si:H structure was designed. An n+-a-Si:H film was deposited on the back of an n-c-Si wafer as the BSF.The photovoltaic performance of p-a-Si:H/n-c-Si/n+-a-Si:H solar cells were simulated. It was shown that the BSF of the p-a-Si:H/n-c-Si/n+-a-Si:H solar cells could effectively inhibit the decrease of the cell performance caused by interface states.

  12. Fusion of Si28+Si28,30: Different trends at sub-barrier energies

    Science.gov (United States)

    Montagnoli, G.; Stefanini, A. M.; Esbensen, H.; Jiang, C. L.; Corradi, L.; Courtin, S.; Fioretto, E.; Grebosz, J.; Haas, F.; Jia, H. M.; Mazzocco, M.; Michelagnoli, C.; Mijatović, T.; Montanari, D.; Parascandolo, C.; Scarlassara, F.; Strano, E.; Szilner, S.; Torresi, D.

    2014-10-01

    Background: The fusion excitation function of the system Si28+Si28 at energies near and below the Coulomb barrier is known only down to ≃15 mb. This precludes any information on both coupling effects on sub-barrier cross sections and the possible appearance of hindrance. For Si28+Si30 even if the fusion cross section is measured down to ≃50 μb, the evidence of hindrance is marginal. Both systems have positive fusion Q values. While Si28 has a deformed oblate shape, Si30 is spherical. Purpose: We investigate 1. the possible influence of the different structure of the two Si isotopes on the fusion excitation functions in the deep sub-barrier region and 2. whether hindrance exists in the Si+Si systems and whether it is strong enough to generate an S-factor maximum, thus allowing a comparison with lighter heavy-ion systems of astrophysical interest. Methods: Si28 beams from the XTU Tandem accelerator of the INFN Laboratori Nazionali di Legnaro were used. The setup was based on an electrostatic beam separator, and fusion evaporation residues (ER) were detected at very forward angles. Angular distributions of ER were measured. Results: Fusion cross sections of Si28+Si28 have been obtained down to ≃600 nb. The slope of the excitation function has a clear irregularity below the barrier, but no indication of a S-factor maximum is found. For Si28+Si30 the previous data have been confirmed and two smaller cross sections have been measured down to ≃4 μb. The trend of the S-factor reinforces the previous weak evidence of hindrance. Conclusions: The sub-barrier cross sections for Si28+Si28 are overestimated by coupled-channels calculations based on a standard Woods-Saxon potential, except for the lowest energies. Calculations using the M3Y+repulsion potential are adjusted to fit the Si28+Si28 and the existing Si30+Si30 data. An additional weak imaginary potential (probably simulating the effect of the oblate Si28 deformation) is required to fit the low-energy trend of

  13. Electrical Performance of Electron Irradiated SiGe HBT and Si BJT

    Institute of Scientific and Technical Information of China (English)

    Wentao HUANG; Jilin WANG; Zhinong LIU; Peiyi CHEN; Peihsin TSIEN; Xiangti MENG

    2004-01-01

    The change of electrical performances of 1 MeV electron irradiated silicon-germanium (SiGe) heterojunction bipolar transistor (HBT) and Si bipolar junction transistor (BJT) was studied. After electron irradiation, both the collector current IC and the base current IB changed a little, and the current gainβ decreased a little for SiGe HBT. The higher the electron irradiation fluence was, the lower the IC decreased. For conventional Si BJT, IC and IB increased as well asβ decreased much larger than SiGe HBT under the same fluence. The contribution of IB was more important to the degradation ofβ for both SiGeHBT and Si BJT. It was shown that SiGe HBT had a larger anti-radiation threshold and better anti-radiation performance than Si BJT. The mechanism of electrical performance changes induced by irradiation was preliminarily discussed.

  14. Propagation of misfit dislocations from buffer/Si interface into Si

    Science.gov (United States)

    Liliental-Weber, Zuzanna; Maltez, Rogerio Luis; Morkoc, Hadis; Xie, Jinqiao

    2011-08-30

    Misfit dislocations are redirected from the buffer/Si interface and propagated to the Si substrate due to the formation of bubbles in the substrate. The buffer layer growth process is generally a thermal process that also accomplishes annealing of the Si substrate so that bubbles of the implanted ion species are formed in the Si at an appropriate distance from the buffer/Si interface so that the bubbles will not migrate to the Si surface during annealing, but are close enough to the interface so that a strain field around the bubbles will be sensed by dislocations at the buffer/Si interface and dislocations are attracted by the strain field caused by the bubbles and move into the Si substrate instead of into the buffer epi-layer. Fabrication of improved integrated devices based on GaN and Si, such as continuous wave (CW) lasers and light emitting diodes, at reduced cost is thereby enabled.

  15. Microstructures and Properties of Ti-Coated SiCp Reinforced Al-Si Alloy Composites

    Science.gov (United States)

    Feng, Yan; Ren, Junpeng; Dong, Cuige; Wang, Richu

    2016-12-01

    A double-layer structure of Ti coating was plated on the surface of SiC particles using a diffusion method in a vacuum reactor, which is a new method to fabricate a Ti-coating layer on the SiC particles. The phase structure of Ti coating on the surface of SiC particles was composed inside of Ti5Si3 and outside of TiC investigated by x-ray diffraction. The Ti5Si3 and TiC double-layer structure realizes the tight chemical bonding between SiC particles and the Ti coating, and significantly promotes the wettability between the aluminum matrix and the Ti-coated SiC particles. The Ti-coated SiCp-reinforced Al-Si composites are prepared by a powder metallurgy method, and express excellent relative densities, desirable mechanical properties and frictional wear resistance.

  16. Study of indentation induced cracks in MoSi2-reaction bonded SiC ceramics

    Indian Academy of Sciences (India)

    O P Chakrabarti; P K Das; S Mondal

    2001-04-01

    MoSi2–RBSC composite samples were prepared by infiltration of Si–2 at.% Mo melt into a preform of commercial SiC and petroleum coke powder. The infiltrated sample had a density > 92% of the theoretical density (TD) and microstructurally contained SiC, MoSi2, residual Si and unreacted C. The material was tested for indentation fracture toughness at room temperature with a Vicker’s indenter and KIC was found to be 4.42 MPa√m which is around 39% higher than the conventional RBSC material. Enhancement in indentation fracture toughness is explained in terms of bowing of propagating cracks through MoSi2/SiC interface which is under high thermal stress arising from the thermal expansion mismatch between MoSi2 and SiC.

  17. Phase transformation in SiOx/SiO₂ multilayers for optoelectronics and microelectronics applications.

    Science.gov (United States)

    Roussel, M; Talbot, E; Pratibha Nalini, R; Gourbilleau, F; Pareige, P

    2013-09-01

    Due to the quantum confinement, silicon nanoclusters (Si-ncs) embedded in a dielectric matrix are of prime interest for new optoelectronics and microelectronics applications. In this context, SiO(x)/SiO₂ multilayers have been prepared by magnetron sputtering and subsequently annealed to induce phase separation and Si clusters growth. The aim of this paper is to study phase separation processes and formation of nanoclusters in SiO(x)/SiO₂ multilayers by atom probe tomography. Influences of the silicon supersaturation, annealing temperature and SiO(x) and SiO₂ layer thicknesses on the final microstructure have been investigated. It is shown that supersaturation directly determines phase separation regime between nucleation/classical growth and spinodal decomposition. Annealing temperature controls size of the particles and interface with the surrounding matrix. Layer thicknesses directly control Si-nc shapes from spherical to spinodal-like structures.

  18. High-performance a -Si/c-Si heterojunction photoelectrodes for photoelectrochemical oxygen and hydrogen evolution

    KAUST Repository

    Wang, Hsin Ping

    2015-05-13

    Amorphous Si (a-Si)/crystalline Si (c-Si) heterojunction (SiHJ) can serve as highly efficient and robust photoelectrodes for solar fuel generation. Low carrier recombination in the photoelectrodes leads to high photocurrents and photovoltages. The SiHJ was designed and fabricated into both photoanode and photocathode with high oxygen and hydrogen evolution efficiency, respectively, by simply coating of a thin layer of catalytic materials. The SiHJ photoanode with sol-gel NiOx as the catalyst shows a current density of 21.48 mA/cm2 at the equilibrium water oxidation potential. The SiHJ photocathode with 2 nm sputter-coated Pt catalyst displays excellent hydrogen evolution performance with an onset potential of 0.640 V and a solar to hydrogen conversion efficiency of 13.26%, which is the highest ever reported for Si-based photocathodes. © 2015 American Chemical Society.

  19. Si3N4/SiC nanocomposite powder from a preceramic polymeric network based on poly(methylsilane as the SiC precursor

    Directory of Open Access Journals (Sweden)

    Maurício F. Gozzi

    2001-01-01

    Full Text Available Si3N4/SiC nanocomposite powders were obtained from a preceramic polymeric network based on poly(methylsilane as the in situ quasi-stoichiometric SiC source. These powders were constituted of nanosized SiC particles homogeneously distributed in the Si3N4 particulate matrix. beta-SiC whiskers were grown at 1400 °C in the pores of the matrix. At 1600 °C, the alpha -> beta Si3N4 phase transition took place, but no elemental silicon from Si3N4 decomposition was detected, evidencing the protective effect of the SiC phase.

  20. Fabrication and characterization of Ti3SiC2–SiC nanocomposite by in situ reaction synthesis of TiC/Si/Al powders

    Indian Academy of Sciences (India)

    Baoyan Liang; Mingzhi Wang; Xiaopu Li; Yunchao Mu

    2011-12-01

    The microstructure and mechanical properties of Ti3SiC2–SiC nanocomposite fabricated by in situ hot pressing (HP) synthesis process were studied. The results show that dense Ti3SiC2–SiC composite contained minor TiSi2 obtained by hot sintering at 1350°C for 1 h. The average grain size of Ti3SiC2 was 4 m in length, and the size of SiC grains is about 100 nm. With its fine microstructure, the Ti3SiC2–SiC nanocomposite shows good mechanical properties.

  1. Switching Performance Evaluation of Commercial SiC Power Devices (SiC JFET and SiC MOSFET) in Relation to the Gate Driver Complexity

    DEFF Research Database (Denmark)

    Pittini, Riccardo; Zhang, Zhe; Andersen, Michael A. E.

    2013-01-01

    and JFETs. The recent introduction of SiC MOSFET has proved that it is possible to have highly performing SiC devices with a minimum gate driver complexity; this made SiC power devices even more attractive despite their device cost. This paper presents an analysis based on experimental results...... of the switching losses of various commercially available Si and SiC power devices rated at 1200 V (Si IGBTs, SiC JFETs and SiC MOSFETs). The comparison evaluates the reduction of the switching losses which is achievable with the introduction of SiC power devices; this includes analysis and considerations...

  2. Photoluminescence and structural properties of Si/SiC core–shell nanowires growth by HWCVD

    Energy Technology Data Exchange (ETDEWEB)

    Nazarudin, Nur Fatin Farhanah Binti; Mohd Noor, Nurul Jannah Binti; Rahman, Saadah Abdul; Goh, Boon Tong, E-mail: boontong77@yahoo.com

    2015-01-15

    Si/SiC core–shell nanowires grown by hot-wire chemical vapor deposition were studied. Ni nanoparticles act as metal nano-templates to catalyze the growth of these core–shell nanowires. These nanowires were grown at different deposition pressures of 0.5 and 1 mbar. The nanowires showed a tapered-like morphology at deposition pressure 0.5 mbar. Increase in pressure to 1 mbar leads to a formation of agglomerated grains at the root of the nanowires. The results show that these nanowires consisted of crystalline Si core and amorphous SiC shell nanowires. Increase in pressure enhanced the formation of SiC phase in the shell of the nanowires. On the other hand, the formation of the agglomerated grains attributed to an increasing of the SiC phase at higher deposition pressure. The presence of Si and SiC nano-crystallites embedded within an amorphous matrix exhibited a room temperature PL emission in the range of 400–1000 nm. The effects of the deposition pressure on the optical and structural properties of the nanowires are also discussed. - Highlights: • Growth of Si/SiC core–shell nanowires by HWCVD. • The nanowires consisted of crystalline Si core and amorphous SiC shell. • Metal nano-templates catalyzed the growth of Si core nanowires. • Increase in deposition pressure enhanced the SiC phase. • The presence of nano-crystallites exhibited a room temperature PL.

  3. Interfacial stability of CoSi2/Si structures grown by molecular beam epitaxy

    Science.gov (United States)

    George, T.; Fathauer, R. W.

    1992-01-01

    The stability of CoSi2/Si interfaces was examined in this study using columnar silicide structures grown on (111) Si substrates. In the first set of experiments, Co and Si were codeposited using MBE at 800 C and the resulting columnar silicide layer was capped by epitaxial Si. Deposition of Co on the surface of the Si capping layer at 800 C results in the growth of the buried silicide columns. The buried columns grow by subsurface diffusion of the deposited Co, suppressing the formation of surface islands of CoSi2. The column sidewalls appear to be less stable than the top and bottom interfaces, resulting in preferential lateral growth and ultimately in the coalescence of the columns to form a continuous buried CoSi2 layer. In the second set of experiments, annealing of a 250 nm-thick buried columnar layer at 1000 C under a 100 nm-thick Si capping layer results in the formation of a surface layer of CoSi2 with a reduction in the sizes of the CoSi2 columns. For a sample having a thicker Si capping layer the annealing leads to Ostwald ripening producing buried equiaxed columns. The high CoSi2/Si interfacial strain could provide the driving force for the observed behavior of the buried columns under high-temperature annealing.

  4. Airborne Emissions from Si/FeSi Production

    Science.gov (United States)

    Kero, Ida; Grådahl, Svend; Tranell, Gabriella

    2016-10-01

    The management of airborne emissions from silicon and ferrosilicon production is, in many ways, similar to the management of airborne emissions from other metallurgical industries, but certain challenges are highly branch-specific, for example the dust types generated and the management of NO X emissions by furnace design and operation. A major difficulty in the mission to reduce emissions is that information about emission types and sources as well as abatement and measurement methods is often scarce, incomplete and scattered. The sheer diversity and complexity of the subject presents a hurdle, especially for new professionals in the field. This article focuses on the airborne emissions from Si and FeSi production, including greenhouse gases, nitrogen oxides, airborne particulate matter also known as dust, polyaromatic hydrocarbons and heavy metals. The aim is to summarize current knowledge in a state-of-the-art overview intended to introduce fresh industry engineers and academic researchers to the technological aspects relevant to the reduction of airborne emissions.

  5. Airborne Emissions from Si/FeSi Production

    Science.gov (United States)

    Kero, Ida; Grådahl, Svend; Tranell, Gabriella

    2017-02-01

    The management of airborne emissions from silicon and ferrosilicon production is, in many ways, similar to the management of airborne emissions from other metallurgical industries, but certain challenges are highly branch-specific, for example the dust types generated and the management of NO X emissions by furnace design and operation. A major difficulty in the mission to reduce emissions is that information about emission types and sources as well as abatement and measurement methods is often scarce, incomplete and scattered. The sheer diversity and complexity of the subject presents a hurdle, especially for new professionals in the field. This article focuses on the airborne emissions from Si and FeSi production, including greenhouse gases, nitrogen oxides, airborne particulate matter also known as dust, polyaromatic hydrocarbons and heavy metals. The aim is to summarize current knowledge in a state-of-the-art overview intended to introduce fresh industry engineers and academic researchers to the technological aspects relevant to the reduction of airborne emissions.

  6. Impact Resistance of Uncoated SiC/SiC Composites

    Science.gov (United States)

    Bhatt, Ramakrishna T.; Choi, Sung R.; Cosgriff, Laura M.; Fox, Dennis S.; Lee, Kang N.

    2008-01-01

    Two-dimensional woven SiC/SiC composites fabricated by melt infiltration method were impact tested at room temperature and at 1316 C in air using 1.59-mm diameter steel-ball projectiles at velocities ranging from 115 to 400 m/s. The extent of substrate damage with increasing projectile velocity was imaged and analyzed using optical and scanning electron microscopy, and non-destructive evaluation (NDE) methods such as pulsed thermography, and computed tomography. The impacted specimens were tensile tested at room temperature to determine their residual mechanical properties. Results indicate that at 115 m/s projectile velocity, the composite showed no noticeable surface or internal damage and retained its as-fabricated mechanical properties. As the projectile velocity increased above this value, the internal damage increased and mechanical properties degraded: At velocities >300 m/s, the projectile penetrated through the composite, but the composite retained approx.50% of the ultimate tensile strength of the as-fabricated composite and exhibited non-brittle failure. Predominant internal damages are delamination of fiber plies, fiber fracture and matrix shearing.

  7. Resonance Raman mapping as a tool to monitor and manipulate Si nanocrystals in Si-SiO{sub 2} nanocomposite

    Energy Technology Data Exchange (ETDEWEB)

    Rani, Ekta; Ingale, Alka A., E-mail: alka@rrcat.gov.in [Laser Physics Applications Section, Raja Ramanna Centre for Advanced Technology, Indore-452013 (India); Homi Bhabha National Institute, Raja Ramanna Centre for Advanced Technology, Indore-452013 (India); Chaturvedi, A. [Laser Material Processing Division, Raja Ramanna Centre for Advanced Technology, Indore-452013 (India); Joshi, M. P.; Kukreja, L. M. [Homi Bhabha National Institute, Raja Ramanna Centre for Advanced Technology, Indore-452013 (India); Laser Material Processing Division, Raja Ramanna Centre for Advanced Technology, Indore-452013 (India)

    2015-10-19

    Specially designed laser heating experiment along with Raman mapping on Si-SiO{sub 2} nanocomposites elucidates the contribution of core and surface/interface in the intermediate frequency range (511–514 cm{sup −1}) Si phonons. The contribution of core to surface/interface increases with the size of Si nanocrystal, which itself increases on laser irradiation. Further, it is found that resonance Raman is crucial to the observance of surface/interface phonons and wavelength dependent Raman mapping can be corroborated with band edges observed in absorption spectra. This understanding can be gainfully used to manipulate and characterize Si-SiO{sub 2} nanocomposite, simultaneously for photovoltaic device applications.

  8. Evaluation of photovoltaic properties of nanocrystalline-FeSi2/Si heterojunctions

    Science.gov (United States)

    Shaban, Mahmoud; Bayoumi, Amr M.; Farouk, Doaa; Saleh, Mohamed B.; Yoshitake, Tsuyoshi

    2016-09-01

    In this paper, an application of nanocrystalline iron disilicide (NC-FeSi2) combined with nanocrystalline-Si (NC-Si) in a heterostructured solar cell is introduced and numerically evaluated in detail. The proposed cell structure is studied based on an experimental investigation of photovoltaic properties of NC-FeSi2/crystalline-Si heterojunctions, composed of unintentionally-doped NC-FeSi2 thin film grown on Si substrate. Photoresponse measurement of NC-FeSi2/crystalline-Si heterojunction confirmed ability of NC-FeSi2 to absorb NIR light and to generate photocarriers. However, collection of these carriers was not so efficient and a radical improvement in design of the device is required. Therefore, a modified device structure, comprising of NC-FeSi2 layer sandwiched between two heavily-doped p- and n-type NC-Si, is suggested and numerically evaluated. Simulation results showed that the proposed structure would exhibit a relatively high conversion efficiency of 25%, due to an improvement in collection efficiency of photogenerated carriers in the NC-FeSi2 and NC-Si layers. To attain such efficiency, defect densities in NC-FeSi2 and NC-Si layers should be kept less than 1014 and 1016 cm-3 eV-1, respectively. Remarkable optical and electrical properties of NC-FeSi2, employed in the proposed structure, facilitate improving device quantum efficiency spectrum providing significant spectrum extension into the near-infrared region beyond Si bandgap.

  9. Hydrogen Passivation Effect on Enhanced Luminescence from Nanocrystalline Si/SiO2 Multilayers

    Institute of Scientific and Technical Information of China (English)

    XIA Zheng-Yue; HAN Pei-Gao; XU Jun; CHEN De-Yuan; WEI De-Yuan; MA Zhong-Yuan; CHEN Kun-Ji; XU Ling; HUANG Xin-Fan

    2007-01-01

    Nanocrystalline Si/SiO2 multilayers are prepared by thermally annealing amorphous Si/SiO2 stacked structures.The photoluminescence intensity is obviously enhanced after hydrogen passivation at various temperatures. It is suggested that the hydrogen trapping and detrapping processes at different temperatures strongly influence the passivation effect. Direct experimental evidence is given by electron spin resonance spectra that hydrogen effectively reduces the nonradiative defect states existing in the Si nanocrystas/SiO2 system which enhances the radiative recombination probability. The luminescence characteristic shows its stability after hydrogen passivation even after aging eight months.

  10. In-Plane Si Nanowire Growth Mechanism in Absence of External Si Flux.

    Science.gov (United States)

    Curiotto, Stefano; Leroy, Frédéric; Cheynis, Fabien; Müller, Pierre

    2015-07-01

    We report on a new mechanism of nanowire formation: during Au deposition on Si(110) substrates, Au-Si droplets grow, move spontaneously, and fabricate a Si nanowire behind them in the absence of Si external flux. Nanowires are formed by Si dissolved from the substrate at the advancing front of the droplets and transported backward to the crystallization front. The droplet shape is determined by the Si etching anisotropy. The nanowire formation can be tuned by changing experimental parameters like substrate temperature and Au deposition rate.

  11. Si/SiO2/p-Si结构的电学特性

    Institute of Scientific and Technical Information of China (English)

    马自军; 马书懿

    2008-01-01

    用射频磁控溅射法在p-Si衬底上制备了Si/SiO2薄膜,利用Au/(Si/SiO2)/p-Si结构的I-V特性曲线对其电学特性进行了分析.结果表明,样品具有很好的整流作用,起整流作用的势垒存在于(Si/SiO2)/p-Si界面附近.

  12. 非晶硅/晶体硅(a-Si/c-Si)异质结%Property Investigation of a-Si/c-Si Hetero-Junction Structure

    Institute of Scientific and Technical Information of China (English)

    汪建强; 高华; 张剑; 张松; 李晨; 叶庆好; 孟凡英

    2011-01-01

    通过对非晶硅/晶体硅(a-Si/c-Si)异质结能带不连续、发射结掺杂以及界面态密度进行分析,研究它们对a-Si/c-Si异质结的界面特性,以及a-Si(N+)/c-Si(P)结构电池性能的影响.研究发现,能带不连续以及a-Si发射结高掺杂有利于实现界面复合机制由以悬挂键复合主导的复合机制向由少数载流子复合占主导的SRH(Shockly-Read-Hall)复合机制转变,有效降低界面复合速率.AFORS-HET软件模拟显示:在c-Si(P)衬底掺杂浓度为1.6×1016cm-3时,a-Si(N+)发射结掺杂浓度大于1.5×1020cm-3是获得高电池效率的必要条件;与短路电流密度相比,开路电压受a-Si/c-Si界面态密度影响更明显.%T his paper investigated the influence ot a-hi/c-bi band ottset, amorphous silicon emitter doping concentration and interface defects density on interface property of a-Si/c-Si structure. Band offset in a-Si(N+ )/c-Si(P) hetero-junction and a-Si emitter high level doping is very useful for the transformation of recombination mechanism from dangling bond to SRH (Shockly-Read-Hall). AFORS-HET simulation indicates that a-Si(N+ ) emitter doping level of over 1. 5X1020 cm~3 on c-Si(P) is an indispensable condition for achieving high efficiency. Comparing with density of short circuit current, open circuit voltage of a-Si/c-Si structure cell is much more susceptible to interface defect density.

  13. SiC nanowires: material and devices

    Science.gov (United States)

    Zekentes, K.; Rogdakis, K.

    2011-04-01

    SiC nanowires are of high interest since they combine the physical properties of SiC with those induced by their low dimensionality. For this reason, a large number of scientific studies have been dedicated to their fabrication and characterization as well as to their application in devices. SiC nanowires' growth involving different growth mechanisms and configurations was the main theme for the large majority of these studies. Various physical characterization methods have been employed for evaluating SiC nanowire quality. SiC nanowires with narrow-diameter (channel material. On the other hand, the grown nanowires are suitable for field-emission applications and to be used as reinforcing material in composite structures as well as for increasing the hydrophobicity of Si surfaces. All these aspects are examined in detail in different sections of this paper.

  14. SiLix-C Nanocomposites

    Science.gov (United States)

    Henry, Francois

    2015-01-01

    For this Phase II project, Superior Graphite Co., in collaboration with the Georgia Institute of Technology and Streamline Nanotechnologies, Inc., developed, explored the properties of, and demonstrated the enhanced capabilities of novel nanostructured SiLix-C anodes. These anodes can retain high capacity at a rapid 2-hour discharge rate and at 0 C when used in Li-ion batteries. In Phase I, these advanced anode materials had specific capacity in excess of 1,000 mAh/g, minimal irreversible capacity losses, and stable performance for 20 cycles at C/1. The goals in Phase II were to develop and apply a variety of novel nanomaterials, fine-tune the properties of composite particles at the nanoscale, optimize the composition of the anodes, and select appropriate binder and electrolytes. In order to achieve a breakthrough in power characteristics of Li-ion batteries, the team developed new nanostructured SiLix-C anode materials to offer up to 1,200 mAh/g at C/2 at 0 C.

  15. siRNA的应用

    Institute of Scientific and Technical Information of China (English)

    孟立根; 马清河; 王安忠; 秦俊文

    2004-01-01

    RNAi(RNA interference,RNA阻断)当初是在研究绦虫C elegans时观测到的一种现象。当将双链的RNA(double stranded RNA;dsRNA)导人体内后,与这种双链RNA相同性较高的mRNA将被特异性地抑制或者消除。除了绦虫之外,RNAi已被作为一种研究基因功能的有效工具,广泛运用于植物、真菌、线虫、果蝇以及哺乳动物,并获得了好的效果。近来使用短链(21~23碱基对)siRNA(short interfering RNA)也获得了同样的效果。siRNA与传统RNA干涉技术相比具有极大的优越

  16. Magnetron-sputter epitaxy of {beta}-FeSi{sub 2}(220)/Si(111) and {beta}-FeSi{sub 2}(431)/Si(001) thin films at elevated temperatures

    Energy Technology Data Exchange (ETDEWEB)

    Liu Hongfei; Tan Chengcheh; Chi Dongzhi [Institute of Materials Research and Engineering (IMRE), A-STAR (Agency for Science, Technology and Research), 3 Research Link, Singapore 117602 (Singapore)

    2012-07-15

    {beta}-FeSi{sub 2} thin films have been grown on Si(111) and Si(001) substrates by magnetron-sputter epitaxy at 700 Degree-Sign C. On Si(111), the growth is consistent with the commonly observed orientation of [001]{beta}-FeSi{sub 2}(220)//[1-10]Si(111) having three variants, in-plane rotated 120 Degree-Sign with respect to one another. However, on Si(001), under the same growth conditions, the growth is dominated by [-111]{beta}-FeSi{sub 2}(431)//[110]Si(001) with four variants, which is hitherto unknown for growing {beta}-FeSi{sub 2}. Photoelectron spectra reveal negligible differences in the valance-band and Fe2p core-level between {beta}-FeSi{sub 2} grown on Si(111) and Si(001) but an apparent increased Si-oxidization on the surface of {beta}-FeSi{sub 2}/Si(001). This phenomenon is discussed and attributed to the Si-surface termination effect, which also suggests that the Si/Fe ratio on the surface of {beta}-FeSi{sub 2}(431)/Si(001) is larger than that on the surface of {beta}-FeSi{sub 2}(220)/Si(111).

  17. Polarization memory effect in the photoluminescence of nc-Si-SiOx light-emitting structures

    Science.gov (United States)

    Michailovska, Katerina; Indutnyi, Ivan; Shepeliavyi, Petro; Sopinskyy, Mykola

    2016-06-01

    The polarization memory (PM) effect in the photoluminescence (PL) of the porous nc-Si-SiOx light-emitting structures, containing nanoparticles of silicon (nc-Si) in the oxide matrix and passivated in a solution of hydrofluoric acid (HF), has been investigated. The studied nc-Si-SiOx structures were produced by evaporation of Si monoxide (SiO) powder in vacuum and oblique deposition on Si wafer, and then the deposited silicon oxide (SiOx) films were annealed in the vacuum at 975 °C to grow nc-Si. It was found that the PM effect in the PL is observed only after passivation of nanostructures: during etching in HF solution, the initial symmetric nc-Si becomes asymmetric elongated. It was also found that in investigated nanostructures, there is a defined orientational dependence of the PL polarization degree ( ρ) in the sample plane which correlates with the orientation of SiOx nanocolumns, forming the structure of the porous layer. The increase of the ρ values in the long-wavelength spectral range with time of HF treatment can be associated with increasing of the anisotropy of large Si nanoparticles. The PM effect for this spectral interval can be described by the dielectric model. In the short-wavelength spectral range, the dependence of the ρ values agrees qualitatively with the quantum confinement effect.

  18. Polarization memory effect in the photoluminescence of nc-Si-SiOx light-emitting structures.

    Science.gov (United States)

    Michailovska, Katerina; Indutnyi, Ivan; Shepeliavyi, Petro; Sopinskyy, Mykola

    2016-12-01

    The polarization memory (PM) effect in the photoluminescence (PL) of the porous nc-Si-SiOx light-emitting structures, containing nanoparticles of silicon (nc-Si) in the oxide matrix and passivated in a solution of hydrofluoric acid (HF), has been investigated. The studied nc-Si-SiOx structures were produced by evaporation of Si monoxide (SiO) powder in vacuum and oblique deposition on Si wafer, and then the deposited silicon oxide (SiOx) films were annealed in the vacuum at 975 °C to grow nc-Si. It was found that the PM effect in the PL is observed only after passivation of nanostructures: during etching in HF solution, the initial symmetric nc-Si becomes asymmetric elongated. It was also found that in investigated nanostructures, there is a defined orientational dependence of the PL polarization degree (ρ) in the sample plane which correlates with the orientation of SiOx nanocolumns, forming the structure of the porous layer. The increase of the ρ values in the long-wavelength spectral range with time of HF treatment can be associated with increasing of the anisotropy of large Si nanoparticles. The PM effect for this spectral interval can be described by the dielectric model. In the short-wavelength spectral range, the dependence of the ρ values agrees qualitatively with the quantum confinement effect.

  19. Study on in-situ Mg2Si/Al-Si composites with different compositions

    Institute of Scientific and Technical Information of China (English)

    Jing Qingxiu; Zhang Caixia; Huang Xiaodong

    2009-01-01

    Effects of chemical composition and heat treatment on microstructures and mechanical properties of in-situ Mg2Si/Al-Si composites were investigated. It was found that, in the microstructure of an Al-5.7wt% Mg2Si composite with 8.2wt% extra Si, the binary eutectic Mg2Si locates at the grain boundaries with an undeveloped Chinese script-like morphology, and the primary α-Al is formed into a cell structure due to the selective modification effect of the modifiers of mischmetal and Strontium salt; whereas in the composite with a near Al-Mg2Si eutectic composition and little extra Si content, the intercrescence eutectic Mg2Si formed with the binary eutectic a-Al grows into integrated Chinese script-like shape. As Si content increases, the eutectic Mg2Si dendrite becomes coarser in morphology but less in volum e fraction. Hardness and tensile strength of the cast Mg2Si/Al-Si composites do not increase with increasing of Mg content, but they are related to the size and morphology of the eutectic and primary Mg2Si phases. Heat treatment with optimal parameters is an effective way to improve the properties of the in-situ composites.

  20. Chemical compatibility issues associated with use of SiC/SiC in advanced reactor concepts

    Energy Technology Data Exchange (ETDEWEB)

    Wilson, Dane F. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)

    2015-09-01

    Silicon carbide/silicon carbide (SiC/SiC) composites are of interest for components that will experience high radiation fields in the High Temperature Gas Cooled Reactor (HTGR), the Very High Temperature Reactor (VHTR), the Sodium Fast Reactor (SFR), or the Fluoride-cooled High-temperature Reactor (FHR). In all of the reactor systems considered, reactions of SiC/SiC composites with the constituents of the coolant determine suitability of materials of construction. The material of interest is nuclear grade SiC/SiC composites, which consist of a SiC matrix [high-purity, chemical vapor deposition (CVD) SiC or liquid phase-sintered SiC that is crystalline beta-phase SiC containing small amounts of alumina-yttria impurity], a pyrolytic carbon interphase, and somewhat impure yet crystalline beta-phase SiC fibers. The interphase and fiber components may or may not be exposed, at least initially, to the reactor coolant. The chemical compatibility of SiC/SiC composites in the three reactor environments is highly dependent on thermodynamic stability with the pure coolant, and on reactions with impurities present in the environment including any ingress of oxygen and moisture. In general, there is a dearth of information on the performance of SiC in these environments. While there is little to no excess Si present in the new SiC/SiC composites, the reaction of Si with O2 cannot be ignored, especially for the FHR, in which environment the product, SiO2, can be readily removed by the fluoride salt. In all systems, reaction of the carbon interphase layer with oxygen is possible especially under abnormal conditions such as loss of coolant (resulting in increased temperature), and air and/ or steam ingress. A global outline of an approach to resolving SiC/SiC chemical compatibility concerns with the environments of the three reactors is presented along with ideas to quickly determine the baseline compatibility performance of SiC/SiC.

  1. Applications of Laser Technologies in Synthesis and Surface Modification of Bioceramic Composite Coatings%激光技术制备生物陶瓷涂层的研究现状与展望

    Institute of Scientific and Technical Information of China (English)

    王迎春; 邓崎林; 朱登洁; 李永祥; 耿铁; 吕翔飞

    2016-01-01

    The applications of laser technologies in synthesis and surface-modification of bio-ceramics compos-ite coating materials,especially hydroxyapatite (HAP)on substrate of biomedical Ti-alloys,were tentatively re-viewed.The discussions focused on i)the laser technologies in growth and surface modification of HAP thick films deposited by plasma-jet spray coating,including but not limited to the laser surface melting of HAP and Ti-alloy substrate,laser-assisted laser ablationdeposition (LALA),pulsed laser deposition (PLD)and laser cladding;ii)the growth mechanisms,optimized growth conditions and characterization of surface and interface properties,particularly biocompatibility,of the HAP grown by PLD;iii)the existing problems of the plasma-jet spray coated HAP thin films in clinic applications,including its poor mechanical behavior.In addition,the development trends and possible solu-tions to the limitations of HAP materials,such as laser melting/rapid solidification and strengthening with carbon nano-tubes(CNTs),were also discussedin a thought provoking way.%羟基磷灰石等生物陶瓷材料具有优良的生物相容性和生物活性,但其强度较低的力学性能限制了其广泛应用.在综合力学性能优良,生物活性有限的医用钛合金表面制备生物陶瓷涂层,能够扬长避短,充分发挥二者的优点,具有巨大的市场与应用价值,是国内外的研究热点.利用激光技术改性或制备生物陶瓷涂层,主要有以下几个领域的应用与研究:激光表面熔凝与其他涂层技术相结合;脉冲激光沉积法;激光熔覆等方法.本文全面阐述了国内外激光表面改性生物陶瓷涂层的研究现状与研究进展,并对其工艺与理论发展进行了展望.

  2. 生物陶瓷热敷结合辩证食疗对脾胃虚寒型胃脘痛患者疗效观察研究%Study the therapy effect on bioceramic compress combined with dialectical spleen-stomach deficiency-cold stomachache patients

    Institute of Scientific and Technical Information of China (English)

    郑芳; 徐静; 陈淑清; 陈艳; 王建

    2013-01-01

    目的:观察生物陶瓷热敷结合辩证食疗治疗脾胃虚寒型胃脘痛的临床疗效.方法:将120例脾胃虚寒性胃脘痛患者随机分为两组,两组在中西医常规治疗基础上,实验组60例,采用生物陶瓷热敷结合辨证食疗,对照组60例仅采用一般中西医常规护理方法.结果:实验组总有效率为86.7%;对照组总有效率为60.0%.两组疗效比较,差异有统计学意义(P<0.05).结论:采用生物陶瓷热敷结合辩证食疗对脾胃虚寒型胃脘痛患者治疗疗效优于中西医常规治疗.%Objective:To observe the clinical curative effect of bioceramic compress dialectical therapeutic treatment of Spleen - stomach deficiency - cold stomachache. Methods A total of 120 patients with spleen deficiency of epigastric pain were randomly divided into two groups, two groups in the routine treatment of Western medicine foundation, experimental group 60 cases, using bioceramic compress combined with syndrome differentiation therapy, 60 cases in control group only with general western medicine routine nursing care. Results : The total effective rate was 86.7% ; the control group in the total efficiency of 60.0% . Comparison of the two groups, the difference was statistically significant ( P < 0. 05). Conclusion The therapy effect of bioceramic compress combined with dialectical therapy of Spleen - stomach deficiency - cold stomachache patients is better than that of treated with integrated traditional Chinese and Western medicine conventional treatment.

  3. One-dimensional Si nanolines in hydrogenated Si(001)

    Science.gov (United States)

    François, Bianco; Köster, Sigrun A.; Owen, James G. H.; Renner, Christoph; Bowler, David R.

    2012-02-01

    We present a detailed study of the structural and electronic properties of a self-assembled silicon nanoline embedded in the H-terminated silicon (001) surface, known as the Haiku stripe. The nanoline is a perfectly straight and defect free endotaxial structure of huge aspect ratio; it can grow micrometre long at a constant width of exactly four Si dimers (1.54 nm). Another remarkable property is its capacity to be exposed to air without suffering any degradation. The nanoline grows independently of any step edges at tunable densities, from isolated nanolines to a dense array of nanolines. In addition to these unique structural characteristics, scanning tunnelling microscopy and density functional theory reveal a one-dimensional state confined along the Haiku core. This nanoline is a promising candidate for the long sought after electronic solid-state one-dimensional model system to explore the fascinating quantum properties emerging in such reduced dimensionality. Phys. Rev. B, 84, 035328 (2011)

  4. The Si/Si_3N4 Interface and Si/Si_3N4 Submicron Mesa: A Multi-million Atom Molecular Dynamics Study

    Science.gov (United States)

    Bachlechner, Martina E.; Omeltchenko, Andrey; Nakano, Aiichiro; Kalia, Rajiv K.; Vashishta, Priya; Ebbsjö, Ingvar; Madhukar, Anupam

    1998-03-01

    Using molecular dynamics simulations on parallel computers, the interface structure, stress distribution, crack propagation and fracture in a Si_3N4 film on Si substrate are studied. Bulk Si is described by Stillinger-Weber potential and Si_3N4 is represented by a combination of two- and three-body covalent interactions. At the interface, the charge transfer is taken from LCAO electronic structure calculations (G.-L. Zhao and M.E. Bachlechner, Europhys. Lett. 36, 287 (1997)). Results for structural correlations at the interface and 3D stress distribution for the submicron mesa are presented.

  5. Graphene/Si-nanowire heterostructure molecular sensors

    Science.gov (United States)

    Kim, Jungkil; Oh, Si Duk; Kim, Ju Hwan; Shin, Dong Hee; Kim, Sung; Choi, Suk-Ho

    2014-06-01

    Wafer-scale graphene/Si-nanowire (Si-NW) array heterostructures for molecular sensing have been fabricated by vertically contacting single-layer graphene with high-density Si NWs. Graphene is grown in large scale by chemical vapour deposition and Si NWs are vertically aligned by metal-assisted chemical etching of Si wafer. Graphene plays a key role in preventing tips of vertical Si NWs from being bundled, thereby making Si NWs stand on Si wafer separately from each other under graphene, a critical structural feature for the uniform Schottky-type junction between Si NWs and graphene. The molecular sensors respond very sensitively to gas molecules by showing 37 and 1280% resistance changes within 3.5/0.15 and 12/0.15 s response/recovery times under O2 and H2 exposures in air, respectively, highest performances ever reported. These results together with the sensor responses in vacuum are discussed based on the surface-transfer doping mechanism.

  6. Si3N4-SiC材料的氧化性能研究%Study on Oxidation Performance of Si3N4-SiC

    Institute of Scientific and Technical Information of China (English)

    李杰

    2009-01-01

    通过对不同Si3N4含量、不同温度下Si3N4-SiC材料的氧化实验,分析氧化后的氧化增重率,得出Si3N4含量越高,材料氧化越严重;氧化温度越高,材料氧化越严重;且氧化增重率与氧化时间呈直线-抛物线规律.

  7. Si isotope homogeneity of the solar nebula

    Energy Technology Data Exchange (ETDEWEB)

    Pringle, Emily A.; Savage, Paul S.; Moynier, Frédéric [Department of Earth and Planetary Sciences and McDonnell Center for the Space Sciences, Washington University in St. Louis, One Brookings Drive, St. Louis, MO 63130 (United States); Jackson, Matthew G. [Department of Earth Science, University of California, Santa Barbara, CA 93109 (United States); Barrat, Jean-Alix, E-mail: eapringle@wustl.edu, E-mail: savage@levee.wustl.edu, E-mail: pringle@ipgp.fr, E-mail: moynier@ipgp.fr, E-mail: jackson@geol.ucsb.edu, E-mail: Jean-Alix.Barrat@univ-brest.fr [Université Européenne de Bretagne, Université de Brest, CNRS UMR 6538 (Domaines Océaniques), I.U.E.M., Place Nicolas Copernic, F-29280 Plouzané Cedex (France)

    2013-12-20

    The presence or absence of variations in the mass-independent abundances of Si isotopes in bulk meteorites provides important clues concerning the evolution of the early solar system. No Si isotopic anomalies have been found within the level of analytical precision of 15 ppm in {sup 29}Si/{sup 28}Si across a wide range of inner solar system materials, including terrestrial basalts, chondrites, and achondrites. A possible exception is the angrites, which may exhibit small excesses of {sup 29}Si. However, the general absence of anomalies suggests that primitive meteorites and differentiated planetesimals formed in a reservoir that was isotopically homogenous with respect to Si. Furthermore, the lack of resolvable anomalies in the calcium-aluminum-rich inclusion measured here suggests that any nucleosynthetic anomalies in Si isotopes were erased through mixing in the solar nebula prior to the formation of refractory solids. The homogeneity exhibited by Si isotopes may have implications for the distribution of Mg isotopes in the solar nebula. Based on supernova nucleosynthetic yield calculations, the expected magnitude of heavy-isotope overabundance is larger for Si than for Mg, suggesting that any potential Mg heterogeneity, if present, exists below the 15 ppm level.

  8. SiD Letter of Intent

    Energy Technology Data Exchange (ETDEWEB)

    Aihara, H., (Ed.); Burrows, P., (Ed.); Oreglia, M., (Ed.); Berger, E.L.; Guarino, V.; Repond, J.; Weerts, H.; Xia, L.; Zhang, J.; /Argonne, HEP; Zhang, Q.; /Argonne, HEP /Beijing, Inst. High Energy Phys.; Srivastava, A.; /Birla Inst. Tech. Sci.; Butler, J.M.; /Boston U.; Goldstein, Joel; Velthuis, J.; /Bristol U.; Radeka, V.; /Brookhaven; Zhu, R.-Y.; /Caltech.; Lutz, P.; /DAPNIA, Saclay; de Roeck, A.; Elsener, K.; Gaddi, A.; Gerwig, H.; /CERN /Cornell U., LNS /Ewha Women' s U., Seoul /Fermilab /Gent U. /Darmstadt, GSI /Imperial Coll., London /Barcelona, Inst. Microelectron. /KLTE-ATOMKI /Valencia U., IFIC /Cantabria Inst. of Phys. /Louis Pasteur U., Strasbourg I /Durham U., IPPP /Kansas State U. /Kyungpook Natl. U. /Annecy, LAPP /LLNL, Livermore /Louisiana Tech. U. /Paris U., VI-VII /Paris U., VI-VII /Munich, Max Planck Inst. /MIT, LNS /Chicago, CBC /Moscow State U. /Nanjing U. /Northern Illinois U. /Obninsk State Nucl. Eng. U. /Paris U., VI-VII /Strasbourg, IPHC /Prague, Inst. Phys. /Princeton U. /Purdue U. /Rutherford /SLAC /SUNY, Stony Brook /Barcelona U. /Bonn U. /UC, Davis /UC, Santa Cruz /Chicago U. /Colorado U. /Delhi U. /Hawaii U. /Helsinki U. /Indiana U. /Iowa U. /Massachusetts U., Amherst /Melbourne U. /Michigan U. /Minnesota U. /Mississippi U. /Montenegro U. /New Mexico U. /Notre Dame U. /Oregon U. /Oxford U. /Ramon Llull U., Barcelona /Rochester U. /Santiago de Compostela U., IGFAE /Hefei, CUST /Texas U., Arlington /Texas U., Dallas /Tokyo U. /Washington U., Seattle /Wisconsin U., Madison /Wayne State U. /Yale U. /Yonsei U.

    2012-04-11

    This document presents the current status of the Silicon Detector (SiD) effort to develop an optimized design for an experiment at the International Linear Collider. It presents detailed discussions of each of SiD's various subsystems, an overview of the full GEANT4 description of SiD, the status of newly developed tracking and calorimeter reconstruction algorithms, studies of subsystem performance based on these tools, results of physics benchmarking analyses, an estimate of the cost of the detector, and an assessment of the detector R and D needed to provide the technical basis for an optimised SiD.

  9. Fabrication and characteristics of the nc-Si/c-Si heterojunction MAGFET

    Institute of Scientific and Technical Information of China (English)

    Zhao Xiaofeng; Wen Dianzhong

    2009-01-01

    A MAGFET using an nc-Si/c-Si heterojunction as source and drain was fabricated by CMOS technology, using two ohm-contact electrodes as Hall outputs on double sides of the channel situated 0.7L from the source. The experimental results show that when V_(DS) = -7.0 V, the magnetic sensitivity of the single nc-Si/c-Si heterojunction magnetic metal oxide semiconductor field effect transistor (MAGFET) with an L : W ratio of 2 : 1 is 21.26 mV/T,and that with an L : W ratio of 4 : 1 is 13.88 mV/T. When the outputs of double nc-Si/c-Si heterojunction MAGFETs with an L : W ratio of 4 : 1 are in series, their magnetic sensitivity is 22.74 mV/T, which is an improvement of about 64% compared with that of a single nc-Si/c-Si heterojunction MAGFET.

  10. 26Si Excited States via One-Neutron Removal from 27Si Using Radioactive Beam

    Science.gov (United States)

    Chen, J.; Chen, A. A.; Amthor, A. M.; Bazin, D.; Becerril, A. D.; Gade, A.; Galaviz, D.; Glasmacher, T.; Kahl, D.; Lorusso, G.; Matos, M.; Ouellet, C. V.; Pereira, J.; Schatz, H.; Smith, K. M.; Wales, B.; Weisshaar, D.; Zegers, R. G. T.

    2013-03-01

    A measurement of the p(27Si, d)26Si reaction has been performed to study levels of 26Si, with connections to the stellar 25Al(p, γ)26Si reaction rate. A beam of adioactive 27Si of energy 84.3 MeV/A was impinged on a polypropylene foil (CH2) of 180 mg/cm2 in thickness. De-excitation γ-rays were detected with a highly-segmented germanium detector array, in coincidence with the 26Si recoils. Our results are an independent measurement of states used in the energy calibration of other experiments on 26Si structure. They also suggest that the spin-parity of the Ex(26Si) = 6454 keV (Er = 940 keV) state should be 4+ instead of the previously adopted assignment of 0+.

  11. W-Mo-Si/SiC Oxidation Protective Coating for Carbon/Carbon Composites

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    A W-Mo-Si/SiC double-layer oxidation protective coating for carbon/carbon (C/C) composites was prepared by a two-step pack cementation technique. XRD (X-ray diffraction) and SEM (scanning electron microscopy)results show that the coating obtained by the first step pack cementation was a thin inner buffer layer of SiC with some cracks and pores, and a new phase of (WxMo1-x)Si2 appeared after the second step pack cementation. Oxidation test shows that, after oxidation in air at 1773 K for 175 h and thermal cycling between 1773 K and room temperature for 18 times, the weight loss of the W-Mo-Si/SiC coated C/C composites was only 2.06%. The oxidation protective failure of the W-Mo-Si/SiC coating was attributed to the formation of some penetrable cracks in the coating.

  12. Nature of visible luminescence of co-sputtered Si-SiO{sub x} systems

    Energy Technology Data Exchange (ETDEWEB)

    Torchynska, T.; Becerril Espinoza, F.G.; Goldstein, Y.; Savir, E.; Jedrzejewski, J.; Khomenkova, L.; Korsunska, N.; Yukhimchuk, V

    2003-12-31

    Photoluminescence (PL) spectra and Raman scattering spectra of Si-SiO{sub x} systems, prepared by radio frequency magnetron sputtering method and thermal annealed at 1150 deg. C for creation of Si nano-crystallites, were investigated as a function of Si content and Si nano-crystallite sizes. It was shown that the PL spectrum of such systems consists of several bands with peak positions at 1.32-1.34, 1.42-1.58, 1.77, 2.05 and 2.30 eV. The dependencies of these PL band parameters on concentration and size of Si nano-crystallites in the Si-SiO{sub x} system have been investigated and analyzed. The nature of radiative optical transitions for all PL bands is discussed.

  13. Optimization of Waveguide Structure for Tunable Optical Switch in Si/SiGe System

    Institute of Scientific and Technical Information of China (English)

    Seongjae Boo; Won-Taek Han

    2003-01-01

    A new electro-optical device using Si/SiGe-system with two parallel ridge waveguides is proposed for optical switching and the optimization of the structure for a single mode operation is investigated.

  14. Characterization of ultrathin SiO 2/Si interface grown by low temperature plasma oxidation

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    Ultrathin SiO 2 layers on Si (100) wafers were prepared by plasma oxidation at a low temperature (250℃). The analyses of X-ray photoelectron spectroscopy (XPS) and TEM reveal that the chemical composition of the oxide layer is stoichiometric SiO 2 and the SiO 2/Si interface is abrupt. The thickness of the ultrathin oxide layer obtained from XPS, capacitance-voltage (C-V) and ellipsometry measurements indicate a nonlinear time dependence. The high frequency C-V characterization of MOS structure shows that the fixed charge density in SiO 2 film is about 10 11 cm -2 . It is also shown that the strength of breakdown electrical field of SiO 2 film with 6 nm thickness is of the order of 10 6 Vcm -1 . These properties of the ultrathin SiO 2 layer ensure its application in silicon quantum devices.

  15. Behaviour of Oxygen-Implanted and Hydrogen-Implanted SiGe/Si Heterostructures

    Institute of Scientific and Technical Information of China (English)

    安正华; 张苗; 门传玲; 沈勤我; 林梓鑫; 李开成; 林成鲁

    2002-01-01

    For SiGe-on-insulator fabrication, a l00nm SiGe tilm with uniform germanium composition was grown on a Si(l00) substrate using a molecular beam epitaxy system without a graded SiGe buffer layer. The samples were implanted by oxygen ions at an energy of 45kev and a dose of 3 × 1017 cm-2, and annealed for five hours at 1250°C in flowing (Ar + 5% 02) atmosphere with a l00nm oxide protective layer. The result indicates that a buried oxide layer was successfully formed at the interface of SiGe and Si on the substrate. Furthermore,hydrogen was implanted into SiGe at the energy of 62keV and the dose of 6 × 1016 cm-2 to perform a blistering study, which confirmed the feasibility of H-induced layer splitting in SiGe layer.

  16. Recycling of Al-Si die casting scraps for solar Si feedstock

    Science.gov (United States)

    Seo, Kum-Hee; Jeon, Je-Beom; Youn, Ji-Won; Kim, Suk Jun; Kim, Ki-Young

    2016-05-01

    Recycling of aluminum die-casting scraps for solar-grade silicon (SOG-Si) feedstock was performed successfully. 3 N purity Si was extracted from A383 die-casting scrap by using the combined process of solvent refining and an advanced centrifugal separation technique. The efficiency of separating Si from scrap alloys depended on both impurity level of scraps and the starting temperature of centrifugation. Impurities in melt and processing temperature governed the microstructure of the primary Si. The purity of Si extracted from the scrap melt was 99.963%, which was comparable to that of Si extracted from a commercial Al-30 wt% Si alloy, 99.980%. The initial purity of the scrap was 2.2% lower than that of the commercial alloy. This result confirmed that die-casting scrap is a potential source of high-purity Si for solar cells.

  17. Thermogravimetric and microscopic analysis of SiC/SiC materials with advanced interfaces

    Energy Technology Data Exchange (ETDEWEB)

    Windisch, C.F. Jr.; Jones, R.H. [Pacific Northwest National Lab., Richland, WA (United States); Snead, L.L. [Oak Ridge National Lab., TN (United States)

    1997-04-01

    The chemical stability of SiC/SiC composites with fiber/matrix interfaces consisting of multilayers of SiC/SiC and porous SiC have been evaluated using a thermal gravimetric analyzer (TGA). Previous evaluations of SiC/SiC composites with carbon interfacial layers demonstrated the layers are not chemically stable at goal use temperatures of 800-1100{degrees}C and O{sub 2} concentrations greater than about 1 ppm. No measureable mass change was observed for multilayer and porous SiC interfaces at 800-1100{degrees}C and O{sub 2} concentrations of 100 ppm to air; however, the total amount of oxidizable carbon is on the order of the sensitivity of the TGA. Further studies are in progress to evaluate the stability of these materials.

  18. Minimum bar size for flexure testing of irradiated SiC/SiC composite

    Energy Technology Data Exchange (ETDEWEB)

    Youngblood, G.E.; Jones, R.H. [Pacific Northwest National Lab., Richland, WA (United States)

    1998-03-01

    This report covers material presented at the IEA/Jupiter Joint International Workshop on SiC/SiC Composites for Fusion structural Applications held in conjunction with ICFRM-8, Sendai, Japan, Oct. 23-24, 1997. The minimum bar size for 4-point flexure testing of SiC/SiC composite recommended by PNNL for irradiation effects studies is 30 {times} 6 {times} 2 mm{sup 3} with a span-to-depth ratio of 10/1.

  19. Passivation of surface-nanostructured f-SiC and porous SiC

    DEFF Research Database (Denmark)

    Ou, Haiyan; Lu, Weifang; Ou, Yiyu;

    The further enhancement of photoluminescence from nanostructured fluorescent silicon carbide (f-SiC) and porous SiC by using atomic layer deposited (ALD) Al2O3 is studied in this paper.......The further enhancement of photoluminescence from nanostructured fluorescent silicon carbide (f-SiC) and porous SiC by using atomic layer deposited (ALD) Al2O3 is studied in this paper....

  20. Fabrication and Properties of Ti3SiC2/SiC Composites

    Institute of Scientific and Technical Information of China (English)

    YIN Hongfeng; FAN Qiang; REN Yun; ZHANG Junzhan

    2008-01-01

    Ti3SiC2/SiC composites were fabricated by reactive hot pressing method. Effects of hot pressing temperature, the content and panicle size of SiC on phase composition, densification, mechanical properties and behavior of stress-strain of the composites were investigated. The results showed that:(1)Hot-pressing temperature influenced the phase composition of Ti3SiC2/SiC composites. The flexural strength and fracture toughness of composites increased with hot pressing temperature.(2)It became more difficult for the composites to densify when the content of SiC in composites increased. It need be sintered at higher temperature to get denser composite. The flexural strength and fracture toughness of composites increased when the content of SiC added in composites increased. However, when the content of SiC reached 50 wt%, the flexural strength and fracture toughness of composites decreased due to high content of pore in composites.(3)When the content of SiC was same, Ti3SiC2/SiC composites were denser while the particle size of SiC added in composites is 12.8μm compared with the composites that the particle size of SiC added is 3μm.The flexural strength and fracture toughness of composites increased with the increase of particle size of SiC added in composites.(4)Ti3SiC2/SiC composites were non-brittle fracture at room temperature.

  1. C-V and DLTS studies of radiation induced Si-SiO2 interface defects

    Science.gov (United States)

    Capan, I.; Janicki, V.; Jacimovic, R.; Pivac, B.

    2012-07-01

    Interface traps at the Si-SiO2 interface have been and will be an important performance limit in many (future) semiconductor devices. In this paper, we present a study of fast neutron radiation induced changes in the density of Si-SiO2 interface-related defects. Interface related defects (Pb centers) are detected before and upon the irradiation. The density of interface-related defects is increasing with the fast neutron fluence.

  2. Electroluminescence and Photoluminescence from Scored Si-Rich SiO2 Film/p-Si Structure

    Institute of Scientific and Technical Information of China (English)

    冉广照; 孙永科; 陈源; 戴伦; 崔晓明; 张伯蕊; 乔永平; 马振昌; 宗婉华; 秦国刚

    2003-01-01

    Electroluminescence (EL) is observed from the Au/Si-rich SiO2 film/p-Si diodes, in which the Si-rich SiO2 films are scored deliberately by a diamond tip. The EL intensity of the scored diode annealed at 800°C is about 6times of that of the unscored counterpart. The EL spectrum of the unscored diode could be decomposed into two Gaussian luminescence bands with peaks at about 1.83 and 2.23 eV, while for the EL spectrum of the scored diode, an additional Gaussian band at about 3.0eV appears, and the 1.83-eV peak increases significantly in intensity. The photoluminescence (PL) spectrum of an unscored Si-rich SiO2 film has only one band peaking at about 1.48eV, whereas the PL spectrum of the scored one has two bands at about 1.48 and 1.97eV. We consider that the high-density defect regions produced by the scoring provide new luminescence centres and become some types of nonradiative centres in the Si oxide layer, which thus result in changes of the EL and PL spectra.

  3. Electroluminescence and Photoluminescence from Scored Si-Rich SiO2 Film/p-Si Structure

    Science.gov (United States)

    Ran, Guang-Zhao; Sun, Yong-Ke; Chen, Yuan; Dai, Lun; Cui, Xiao-Ming; Zhang, Bo-Rui; Qiao, Yong-Ping; Ma, Zhen-Chang; Zong, Wan-Hua; Qin, Guo-Gang

    2003-02-01

    Electroluminescence (EL) is observed from the Au/Si-rich SiO2 film/p-Si diodes, in which the Si-rich SiO2 films are scored deliberately by a diamond tip. The EL intensity of the scored diode annealed at 800°C is about 6 times of that of the unscored counterpart. The EL spectrum of the unscored diode could be decomposed into two Gaussian luminescence bands with peaks at about 1.83 and 2.23 eV, while for the EL spectrum of the scored diode, an additional Gaussian band at about 3.0 eV appears, and the 1.83-eV peak increases significantly in intensity. The photoluminescence (PL) spectrum of an unscored Si-rich SiO2 film has only one band peaking at about 1.48 eV, whereas the PL spectrum of the scored one has two bands at about 1.48 and 1.97 eV. We consider that the high-density defect regions produced by the scoring provide new luminescence centres and become some types of nonradiative centres in the Si oxide layer, which thus result in changes of the EL and PL spectra.

  4. Microwave Sintering of MoSi2 and SiC/MoSi2 Nanocomposite Ceramics%微波烧结制备MoSi2及SiC/MoSi纳米复合陶瓷

    Institute of Scientific and Technical Information of China (English)

    刘长虹; 艾云龙; 何文

    2012-01-01

    MoSi2 and SiC/MoSi2 nanocomposite ceramics were prepared by microwave sintering. Hybrid heating using SiC as preheating material and reasonable design of heat preservation system realized the fast elevation of temperature of MoSi2 on the low temperature stage, and enhanced the temperature uniformity of MoSi2. The density and mechanical properties tests showed that under the sintering parameters of 1 400℃ and holding 60 min, the properties of pure MoSi2 sample achieved relative density of 93.4% , fracture toughness 4.5 MPa·m1/2, Vickers hardness 10.53 GPa, and bending strength 186 MPa. All the mechanical properties of 10vol. % SiC -MoSi2 were superior to that of pure MoSi2, though the relative density decreased to 90.3%. The temperature of microwave sintering MoSi2 and SiC/ MoSi2 samples decreased 200℃ lower than hot-pressing sintering temperature (1 650℃ ) , but the mechanical properties are actually enhanced greatly, in particular MoSi2sample. Fracture surfaces indicated that compared to hot-pressing sintered samples,the microwave sintered samples presented refined grain size, fine and uniform pore. However the effect of grain refinement of microwave sintering to SiC/MoSi2 is weaken compared to pure MoSi2 sample.%采用微波烧结法制备了MoSi2和10vol% SiC/MoSi2纳米复合陶瓷.通过SiC预加热体的混合式加热法和合理的保温结构设计,实现了MoSi2低温阶段的快速升温,提高了温度均匀性.密度和力学性能测试结果表明,1450℃保温60 min烧结工艺下,MoSi2试样的相对密度达到93.4%,断裂韧度4.5 MPa·ml/2,维氏硬度为10.53 GPa,弯曲强度为186 MPa.10vol% SiC/MoSi2试样尽管相对密度下降为90.3%,但各项力学性能均优于MoSi2试样.相比1650℃热压烧结,微波烧结温度降低了200℃,MoSi2和SiC/MoSi2试样致密性有所下降,但力学性能有较大提高,尤其是MoSi2试样.断口扫描分析表明,微波烧结试样相对热压烧结试样基体晶粒更细,孔隙细

  5. The effect of biaxial strain on impurity diffusion in Si and SiGe

    DEFF Research Database (Denmark)

    Larsen, Arne Nylandsted; Zangenberg, Nikolaj; Fage-Pedersen, Jacob

    2005-01-01

    Results from diffusion studies of different impurities in biaxially strained Si and Si"1"-"xGe"x for low x-values will be presented. The structures are all molecular-beam epitaxy (MBE) grown on strain-relaxed Si"1"-"xGe"x layers, and the impurity profiles are introduced during growth. We have...

  6. Enhanced electroluminescence from nanocrystallite Si based MOSLED by interfacial Si nanopyramids

    Institute of Scientific and Technical Information of China (English)

    Gong-Ru Lin

    2007-01-01

    The interfacial Si nano-pyramid-enhanced electroluminescence (EL) of an ITO/SiOx/p-Si/Al metal-oxidesemiconductor (MOS) diode with turn-on voltage of 50 V, threshold current of 1.23 mA/cm2, output power of 16 nW, and lifetime of 10 h is reported.

  7. About the International System of Units (SI) Part III. SI Table

    Science.gov (United States)

    Aubrecht, Gordon J., II; French, Anthony P.; Iona, Mario

    2012-01-01

    Before discussing more details of SI, we will summarize the essentials in a few tables that can serve as ready references. If a unit isn't listed in Tables I-IV, it is not part of SI or specifically allowed for use with SI. The units and symbols that are sufficient for most everyday applications are given in bold.

  8. Preparation of Si3N4–SiC composites by microwave route

    Indian Academy of Sciences (India)

    M Panneerselvam; K J Rao

    2002-12-01

    Si3N4–SiC composites have been microwave sintered using -Si3N4 and -SiC as starting materials. Si3N4 rich compositions (95 and 90 vol.% Si3N4) have been sintered above 96% of theoretical density without using any sintering additives in 40 min. A monotonic decrease in relative density is observed with increase in SiC proportion in the composite. Decrease in relative density has manifested in the reduction of fracture toughness and microhardness values of the composite with increase in SiC content although the good sintering of matrix Si3N4 limits the decrease of fracture toughness. Highest value of fracture toughness of 6.1 MPa m1/2 is observed in 10 vol.% SiC composite. Crack propagation appears to be transgranular in the Si3N4 matrix and the toughening of the composites is through crack deflection around hard SiC particles in addition to its debonding from the matrix.

  9. Microstructure and abrasive wear studies of laser clad Al-Si/SiC composite coatings

    NARCIS (Netherlands)

    Anandkumar, R.; Colaco, R.; Ocelik, V.; De Hosson, J. Th. M.; Vilar, R.; Gyulai, J; Szabo, PJ

    2007-01-01

    Surface coatings of Al-Si/SiC metal-matrix composites were deposited on Al-7 wt. % Si alloy substrates by laser cladding. The microstructure of the coatings was characterized by optical microscopy, scanning electron microscopy (SEM) and X-ray diffraction (XRD). The microstructure of the coating mate

  10. Polycrystalline SiC as source material for the growth of fluorescent SiC layers

    DEFF Research Database (Denmark)

    Kaiser, M.; Hupfer, T.; Jokubavicus, V.;

    2013-01-01

    Polycrystalline doped SiC act as source for fluorescent SiC. We have studied the growth of individual grains with different polytypes in the source material. We show an evolution and orientation of grains of different polytypes in polycrystalline SiC ingots grown by the Physical Vapor Transport...

  11. Silane photoabsorption spectra near the Si 2p thresholds: the geometry of Si 2p excited SiH4

    Institute of Scientific and Technical Information of China (English)

    张卫华; 许如清; 李家明

    2003-01-01

    Based on the multiple-scattering self-consistent-field method, we have studied the photoabsorption spectra near the Si 2p thresholds of silane. According to our calculations, the clear assignments of the inner-shell photoabsorption spectra are provided. In comparison with the high-resolution experimental spectra, the geometric structure of the Si 2p-excited SiH4** is recommended to be of a C2v symmetry. More specifically, the Si 2p-excited Si4** have two bond lengths of 2.50 a.u. and another two bond lengths of 2.77 a.u., and the corresponding two bond angles are 104.0° and 112.5° respectively.

  12. Thermochemical instability effects in SiC-based fibers and SiC{sub f}/SiC composites

    Energy Technology Data Exchange (ETDEWEB)

    Youngblood, G.E.; Henager, C.H.; Jones, R.H. [Pacific Northwest National Laboratory, Richland, WA (United States)

    1997-08-01

    Thermochemical instability in irradiated SiC-based fibers with an amorphous silicon oxycarbide phase leads to shrinkage and mass loss. SiC{sub f}/SiC composites made with these fibers also exhibit mass loss as well as severe mechanical property degradation when irradiated at 800{degrees}C, a temperature much below the generally accepted 1100{degrees}C threshold for thermomechanical degradation alone. The mass loss is due to an internal oxidation mechanism within these fibers which likely degrades the carbon interphase as well as the fibers in SiC{sub f}/SiC composites even in so-called {open_quotes}inert{close_quotes} gas environments. Furthermore, the mechanism must be accelerated by the irradiation environment.

  13. Tunneling magnetoresistance in Si nanowires

    Science.gov (United States)

    Montes, E.; Rungger, I.; Sanvito, S.; Schwingenschlögl, U.

    2016-11-01

    We investigate the tunneling magnetoresistance of small diameter semiconducting Si nanowires attached to ferromagnetic Fe electrodes, using first principles density functional theory combined with the non-equilibrium Green’s functions method for quantum transport. Silicon nanowires represent an interesting platform for spin devices. They are compatible with mature silicon technology and their intrinsic electronic properties can be controlled by modifying the diameter and length. Here we systematically study the spin transport properties for neutral nanowires and both n and p doping conditions. We find a substantial low bias magnetoresistance for the neutral case, which halves for an applied voltage of about 0.35 V and persists up to 1 V. Doping in general decreases the magnetoresistance, as soon as the conductance is no longer dominated by tunneling.

  14. Tunneling magnetoresistance in Si nanowires

    KAUST Repository

    Montes Muñoz, Enrique

    2016-11-09

    We investigate the tunneling magnetoresistance of small diameter semiconducting Si nanowires attached to ferromagnetic Fe electrodes, using first principles density functional theory combined with the non-equilibrium Green\\'s functions method for quantum transport. Silicon nanowires represent an interesting platform for spin devices. They are compatible with mature silicon technology and their intrinsic electronic properties can be controlled by modifying the diameter and length. Here we systematically study the spin transport properties for neutral nanowires and both n and p doping conditions. We find a substantial low bias magnetoresistance for the neutral case, which halves for an applied voltage of about 0.35 V and persists up to 1 V. Doping in general decreases the magnetoresistance, as soon as the conductance is no longer dominated by tunneling.

  15. Experimental PDT: studies on new Si-phthalocyanines and Si-naphthalocyanines in Cremophor emulsions

    Science.gov (United States)

    Shopova, Maria; Mantareva, Vanya; Woehrle, Dieter; Mueller, Silke

    1996-12-01

    In the present work the following silicon (IV) - phthalocyanines and -naphthalocyanines bearing methoxyethylene glycol or methoxypolyethylene glycol covalently bound at the silicon are investigated: SiPc[OCH2CH2OCH3]2 (SiPc1), SiNc[OCH2CH2OCH3]2 (SiNc), SiPc[(OCH2CH2)nOCH3] with n approximately 115 (SiPc2). The phototherapeutic effect was shown at Lewis lung carcinoma implanted in mice. SiPc2 is monomeric soluble in water whereas the other two compounds aggregated in this solvent. Therefore these compounds were dissolved monomer in in aqueous Cremophor solution before in vivo administration. Laser irradiation was applied 7 days after implantation and 24 h after drug administration at the following wavelength (eta) ext: 672 nm for SiPc1 and SiPc2, 782 nm for SiNc. In all cases a fluence rate of 370 mW/cm2 at fluence of 360 J/cm2 was used. The assessment criteria for the tumor response were the changes in the mean tumor diameter with time, regrowth delay and average survival time (AST). According to the first parameter the most promising result was obtained after treatment with SiPc1. For example the mean tumor diameter increases as follows: SiPc1 less than SiPc2 less than SiNc very much less than control group without photosensitizer. The regrowth delay showed the same trend. however, for AST another dependence was observed. AST was the longest for SiPc2 (26 days) and shortest for SiNc (22 days). Compared to the control group (without sensitizer and irradiation) the AST was 9 days longer after SiPc2 treatment. Comparing SiPc1 and SiPc2 the chain length of the substituents does not influence the phototherapeutic properties. The detected therapeutic results probably are connected with the long wavelength absorption of the photosensitizers. The relatively lower affectivity of SiNc may be due to a lower degree of tumor accumulation as it was observed in our preliminary pharmacokinetic studies. It is also possible that the shorter AST after treatment with SiNc is

  16. Metastability of a-SiOx:H thin films for c-Si surface passivation

    Science.gov (United States)

    Serenelli, L.; Martini, L.; Imbimbo, L.; Asquini, R.; Menchini, F.; Izzi, M.; Tucci, M.

    2017-01-01

    The adoption of a-SiOx:H films obtained by PECVD in heterojunction solar cells is a key to further increase their efficiency, because of its transparency in the UV with respect to the commonly used a-Si:H. At the same time this layer must guarantee high surface passivation of the c-Si to be suitable in high efficiency solar cell manufacturing. On the other hand the application of amorphous materials like a-Si:H and SiNx on the cell frontside expose them to the mostly energetic part of the sun spectrum, leading to a metastability of their passivation properties. Moreover as for amorphous silicon, thermal annealing procedures are considered as valuable steps to enhance and stabilize thin film properties, when performed at opportune temperature. In this work we explored the reliability of a-SiOx:H thin film layers surface passivation on c-Si substrates under UV exposition, in combination with thermal annealing steps. Both p- and n-type doped c-Si substrates were considered. To understand the effect of UV light soaking we monitored the minority carriers lifetime and Sisbnd H and Sisbnd O bonding, by FTIR spectra, after different exposure times to light coming from a deuterium lamp, filtered to UV-A region, and focused on the sample to obtain a power density of 50 μW/cm2. We found a certain lifetime decrease after UV light soaking in both p- and n-type c-Si passivated wafers according to a a-SiOx:H/c-Si/a-SiOx:H structure. The role of a thermal annealing, which usually enhances the as-deposited SiOx passivation properties, was furthermore considered. In particular we monitored the UV light soaking effect on c-Si wafers after a-SiOx:H coating by PECVD and after a thermal annealing treatment at 300 °C for 30 min, having selected these conditions on the basis of the study of the effect due to different temperatures and durations. We correlated the lifetime evolution and the metastability effect of thermal annealing to the a-SiOx:H/c-Si interface considering the evolution

  17. Preparation and characterization of porous bioceramic scaffold based on additive manufacturing and gel-casting technology%基于增材制造和凝胶注模成型技术的多孔生物陶瓷支架制备与表征

    Institute of Scientific and Technical Information of China (English)

    2013-01-01

    Objective To investigate a novel method for the preparation of porous bioceramic scaffold ofβ-tricalcium phosphate (TCP) based on additive manufacturing and gel-casting technology. Methods Internal porous structures of scaffold were designed by computer aided design (CAD) software, resin molds were produced by stereolithography, then the bioceramic slurry were cast into the molds, and were sintered to remove the resin mold after hardening. As a result, the porous bioceramic scaffolds of β-TCP were obtained. Characteristics of microcosmic pore structures, mechanical properties and cell compatibility of the scaffolds were examined subsequently. Results Porous structures of β-TCP scaffold were consistent with the original design, with the interval porosity of 45.1% ± 1.2%. and the pore size of 300 to 500 μm; The average compressive strength was 5.3 ± 0.8 MPa;The results of in vitro test showed that osteoblasts were well attached and spread on scaffold, which indicated that the porous scaffold had good biocompatibility. Conclusion A novel method based on additive manufacturing and gel-casting technology has been proposed to produce porous bioceramic scaffold, which can provide scaffolds with complex shape and controlled internal porous structures.%  目的探讨基于增材制造和凝胶注模成型技术的多孔β-磷酸三钙(TCP)生物陶瓷支架的制备方法及其表征。方法利用计算机辅助设计(CAD)软件设计支架内部孔隙结构,通过光固化快速成型技术制造相应的树脂模具,在模具中填充生物材料,待其固化后通过热分解去除树脂模具,然后对所形成的多孔β-TCP支架的微观孔隙结构特征、力学性能以及体外细胞相容性进行检测。结果多孔β-TCP支架孔隙结构与设计结构一致,孔隙率为45.1%±1.2%,孔的尺寸为300~500μm;力学性能测试表明,支架的平均抗压强度为5.3±0.8 MPa;成骨细胞能够在支架上黏附生长

  18. Lateral boron distribution in polycrystalline SiC source materials

    DEFF Research Database (Denmark)

    Linnarsson, M. K.; Kaiser, M.; Liljedahl, R.

    2013-01-01

    Polycrystalline SiC containing boron and nitrogen are used in growth of fluorescent SiC for white LEDs. Two types of doped polycrystalline SiC have been studied in detail with secondary ion mass spectrometry: sintered SiC and poly-SiC prepared by sublimation in a physical vapor transport setup...

  19. Advances in wide bandgap SiC for optoelectronics

    DEFF Research Database (Denmark)

    Ou, Haiyan; Ou, Yiyu; Argyraki, Aikaterini

    2014-01-01

    . This paper will review the advances in fluorescent SiC for white light-emitting diodes, covering the poly-crystalline doped SiC source material growth, single crystalline epitaxy growth of fluorescent SiC, and nanofabrication of SiC to enhance the extraction efficiency for fluorescent SiC based white LEDs....

  20. Monolithic integration of Si-MOSFET and GaN-LED using Si/SiO2/GaN-LED wafer

    Science.gov (United States)

    Tsuchiyama, Kazuaki; Yamane, Keisuke; Utsunomiya, Shu; Sekiguchi, Hiroto; Okada, Hiroshi; Wakahara, Akihiro

    2016-10-01

    In this report, we present a monolithic integration method for a Si-MOSFET and a GaN-LED onto a Si/SiO2/GaN-LED wafer as an elemental technology for monolithic optoelectronic integrated circuits. To enable a Si-MOSFET device process, we investigated the thermal tolerance of a thin top-Si and GaN-LED layer on a Si/SiO2/GaN-LED wafer. The high thermal tolerance of the Si/SiO2/GaN-LED structure allowed for the monolithic integration of a Si n-MOSFET and a GaN-µLED without degrading the performance of either device. A GaN-µLED driver circuit was fabricated using a Si n-MOSFET and a µLED of 30 × 30 µm2, with the modulation bandwidth of the circuit estimated to be over 10 MHz.

  1. Optical properties of passivated Si nanocrystals and SiO{sub {ital x}} nanostructures

    Energy Technology Data Exchange (ETDEWEB)

    Dinh, L.N. [Department of Applied Science, University of California, Davis/Livermore, California (United States)]|[Chemistry and Materials Science Department, University of California, Lawrence Livermore National Laboratory, Livermore, California 94550 (United States); Chase, L.L.; Balooch, M.; Siekhaus, W.J. [Chemistry and Materials Science Department, University of California, Lawrence Livermore National Laboratory, Livermore, California 94550 (United States); Wooten, F. [Department of Applied Science, University of California, Davis/Livermore, California 94550 (United States)

    1996-08-01

    Thin films of Si nanoclusters passivated with oxygen or hydrogen, with an average size of a few nanometers, have been synthesized by thermal vaporization of Si in an Ar buffer gas, followed by subsequent exposure to oxygen or atomic hydrogen. High-resolution transmission electron microscopy and x-ray diffraction revealed that these nanoclusters were crystalline. However, during synthesis, if oxygen was the buffer gas, a network of amorphous Si oxide nanostructures (an-SiO{sub {ital x}}) with occasional embedded Si dots was formed. All samples showed strong infrared and/or visible photoluminescence (PL) with varying decay times from nanoseconds to microseconds depending on synthesis conditions. Absorption in the Si cores for surface passivated Si nano- crystals (nc-Si), but mainly in oxygen related defect centers for an-SiO{sub {ital x}}, was observed by photoluminescence excitation spectroscopy. The visible components of PL spectra were noted to blueshift and broaden as the size of the nc-Si was reduced. There were differences in PL spectra for hydrogen and oxygen passivated nc-Si. Many common PL properties between oxygen passivated nc-Si and an-SiO{sub {ital x}} were observed. Our data can be explained by a model involving absorption between quantum confined states in the Si cores and emission for which the decay times are very sensitive to surface and/or interface states. The emission could involve a simple band-to-band recombination mechanism within the Si cores. The combined evidence of all of our experimental results suggests, however, that emission between surface or interface states is a more likely mechanism. {copyright} {ital 1996 The American Physical Society.}

  2. Optical properties of passivated Si nanocrystals and SiOx nanostructures

    Science.gov (United States)

    Dinh, L. N.; Chase, L. L.; Balooch, M.; Siekhaus, W. J.; Wooten, F.

    1996-08-01

    Thin films of Si nanoclusters passivated with oxygen or hydrogen, with an average size of a few nanometers, have been synthesized by thermal vaporization of Si in an Ar buffer gas, followed by subsequent exposure to oxygen or atomic hydrogen. High-resolution transmission electron microscopy and x-ray diffraction revealed that these nanoclusters were crystalline. However, during synthesis, if oxygen was the buffer gas, a network of amorphous Si oxide nanostructures (an-SiOx) with occasional embedded Si dots was formed. All samples showed strong infrared and/or visible photoluminescence (PL) with varying decay times from nanoseconds to microseconds depending on synthesis conditions. Absorption in the Si cores for surface passivated Si nano- crystals (nc-Si), but mainly in oxygen related defect centers for an-SiOx, was observed by photoluminescence excitation spectroscopy. The visible components of PL spectra were noted to blueshift and broaden as the size of the nc-Si was reduced. There were differences in PL spectra for hydrogen and oxygen passivated nc-Si. Many common PL properties between oxygen passivated nc-Si and an-SiOx were observed. Our data can be explained by a model involving absorption between quantum confined states in the Si cores and emission for which the decay times are very sensitive to surface and/or interface states. The emission could involve a simple band-to-band recombination mechanism within the Si cores. The combined evidence of all of our experimental results suggests, however, that emission between surface or interface states is a more likely mechanism.

  3. Synthesis of Hybrid SiC/SiO2 Nanoparticles and Their Polymer Nanocomposites

    Science.gov (United States)

    Hassan, Tarig A.; Rangari, Vijaya K.; Baker, Fredric; Jeelani, Shaik

    2013-04-01

    In the present investigation, silicon carbide (β-SiC) nanoparticles ( 30 nm) were coated on silicon dioxide (SiO2) nanoparticles ( 200 nm) using sonochemical method. The resultant hybrid nanoparticles were then infused into SC-15 epoxy resin to enhance the thermal and mechanical properties of SC-15 epoxy for structural application. To fabricate an epoxy-based nanocomposite containing SiC/SiO2 hybrid nanoparticles, we have opted a two-step process. In the first step, the silica nanoparticles were coated with SiC nanoparticles using high intensity ultrasonic irradiation. In a second step, 1 wt.% of as-prepared SiC/SiO2 particles were dispersed in epoxy part-A (diglycidylether of bisphenol A) using a high intensity ultrasound for 30 min at 5°C. The part-B (cycloaliphatic amine hardener) of the epoxy was then mixed with part-A-SiC/SiO2 mixture using a high-speed mechanical stirrer for 10 min. The SiC/SiO2/epoxy resin mixture was cured at room temperature for 24 h. The SiC nanoparticles coating on SiO2 was characterized using X-ray diffraction (XRD) and high resolution transmission electron microscope (TEM). The as-prepared nanocomposite samples were characterized using thermo gravimetric analysis (TGA) and differential scanning calorimeter (DSC). Compression tests have been carried out for both nanocomposite and neat epoxy systems. The results indicated that 1 wt.% (SiC) + (SiO2) loading derived improvements in both thermal and mechanical properties when compared to the neat epoxy system.

  4. Effects of the use of MIG3 bioceramics fabrics use - long infrared emitter - in pain, intolerance to cold and periodic limb movements in post-polio syndrome Efeitos do uso de tecidos com biocerâmica MIG3 - emissora de infravermelho longo - na dor, intolerância ao frio e movimentos periódicos dos membros na síndrome pós-poliomielite

    Directory of Open Access Journals (Sweden)

    Tatiana Mesquita e Silva

    2009-12-01

    Full Text Available The main post-polio syndrome (PPS symptoms are new-onset weakness, new-onset atrophy, fatigue, cold intolerance, and pain associated with sleep disturbances. The polysomnographic study is the gold pattern to analyze sleep disorders. OBJECTIVE: To assess pain, intolerance to cold and periodic limb movements (PLM index before and after the use of MIG3 bioceramic fabrics over 4 weeks. METHOD: 12 patients with PPS from UNIFESP/EPM. All patients were submitted to polysomnography and infra-red examinations with answered scales of pain and intolerance to cold before and after the use of MIG3 bioceramics fabrics. RESULTS: There were significant decreases in pain and PLM index. CONCLUSION: MIG3 bioceramic fabrics can help in the treatment of pain and PLM in PPS patients.Dentre as manifestações clínicas da SPP destacam-se nova fraqueza, fadiga, dor, intolerância ao frio, nova atrofia e transtornos do sono. A polissonografia de noite inteira permanece sendo padrão ouro para análise do sono e diagnóstico de transtornos do sono. OBJETIVO: Avaliar o comportamento da dor, intolerância ao frio (IF e índice de movimentos periódicos de membros (PLMs após uso de colchonete e roupas com biocerâmica MIG3 por 4 semanas. MÉTODO: 12 pacientes com SPP, da UNIFESP/EPM. Todos realizaram exames de polissonografia e infravermelho e responderam a questionários de dor e IF antes e após o uso dos materiais. RESULTADOS: Houve diminuição significativa da dor e dos PLMs. CONCLUSÃO: Os tecidos com biocerâmica MIG3 podem ser um coadjuvante ao tratamento da dor e dos PLMs nos pacientes com SPP.

  5. DLC-Si protective coatings for polycarbonates

    Directory of Open Access Journals (Sweden)

    Damasceno J.C.

    2003-01-01

    Full Text Available In this work, a-C:H:Si (DLC-Si films were produced onto crystalline silicon and polycarbonate substrates by the rf-PACVD technique from gaseous mixtures of CH4 + SiH4 and C2H2 + SiH4. The effects of self-bias and gas composition upon mechanical and optical properties of the films were investigated. Micro-hardness, residual stress, surface roughness and refractive index measurements were employed for characterization. By incorporating low concentrations of silicon and by exploring the more favorable conditions for the rf-PACVD deposition technique, highly adherent DLC-Si thin films were produced with reduced internal stresses (lower than 1 GPa, high hardness (around 20 GPa and high deposition rates (up to 10 µm/h. Results that show the technological viability of this material for application as protective coatings for polycarbonates are also discussed.

  6. Biomorphic SiC from lotus root

    Institute of Scientific and Technical Information of China (English)

    Qing Wang; Donghua Wang; Guoqiang Jin; Yingyong Wang; Xiangyun

    2009-01-01

    Biomorphic silicon carbide (bioSiC) with macro-channels and alveolate micropores was prepared by spon-taneous infiltration of melted silicon into a carbon template derived from lotus root at 1600 ℃. The carbon template and purified bioSiC samples were characterized by X-ray diffraction, scanning electron microscopy, camera and mercury intrusion. The results suggest that the bioSiC mainly consists of β-SiC and perfectly replicates the shape and microstructure of the carbon template. The bioSiC has a mean pore diameter of 91.1 μm and a porosity of 50.1%, both similar to those of the carbon template, 92.3 μm and 50.7%, respectively.

  7. High Efficiency Hybrid Solar Cells Using Nanocrystalline Si Quantum Dots and Si Nanowires.

    Science.gov (United States)

    Dutta, Mrinal; Thirugnanam, Lavanya; Trinh, Pham Van; Fukata, Naoki

    2015-07-28

    We report on an efficient hybrid Si nanocrystal quantum dot modified radial p-n junction thinner Si solar cell that utilizes the advantages of effective exciton collection by energy transfer from nanocrystal-Si (nc-Si) quantum dots to underlying radial p-n junction Si nanowire arrays with excellent carrier separation and propagation via the built-in electric fields of radial p-n junctions. Minimization of recombination, optical, and spectrum losses in this hybrid structure led to a high cell efficiency of 12.9%.

  8. Deep levels, transport and THz emission properties of SiGe/Si quantum-well structures

    Institute of Scientific and Technical Information of China (English)

    I.; V.; ANTONOVA; M.; S.; KAGAN; E.; P.; NEUSTROEV; S.; A.; SMAGULOVA

    2009-01-01

    Recharging of quantum confinement levels in SiGe quantum wells (QW) was studied by charge deep-level transient spectroscopy (Q-DLTS) for Si/SiGe/Si structures with different Ge contents in the SiGe layer. A peak with activation energy varying in the range from 0 to 100 meV in different tempera-ture intervals was observed in Q-DLTS spectra. Activation energies extracted from Q-DLTS measure-mens are in good agreement with energies of quantum confinement levels in the QW.

  9. Next Generation, Si-Compatible Materials and Devices in the Si-Ge-Sn System

    Science.gov (United States)

    2015-10-09

    performed extensive growth studies aimed to create entire new families of Ge1-x-ySixSny materials on industrially compatible group IV platforms ( Si , Ge and...AFRL-AFOSR-VA-TR-2016-0044 Next generation, Si -compatible materials and devices in the Si -Ge-Sn system John Kouvetakis ARIZONA STATE UNIVERSITY Final...4. TITLE AND SUBTITLE Next generation, Si -compatible materials and devices in the Si -Ge-Sn system 5a. CONTRACT NUMBER FA9550-12-1-0208 5b. GRANT

  10. Influence of Si content and heat treatment on microstructure of Al-Fe-Si alloys

    Institute of Scientific and Technical Information of China (English)

    Zhao Yuhua; Wang Xiubin; Liu Yulin; Wang Chao

    2014-01-01

    The effect of Si addition and heat treatment on the Al-5wt.%Fe al oy has been investigated by OM, SEM-EDS and XRD. The results show that the Si plays a significant role in refining the primary Al3Fe phase. It was found that the addition of 3.0wt.% Si made the al oy present the finest and wel -distributed primary Al3Fe phase, but the Al3Fe phase almost disappeared when 5wt.% Si was added. With further increase in the Si content, some Fe-rich phases appeared in the inter-grains and coarsened. In addition, the heat treatments exert a significant impact on the microstructural evolution of the Al-5wt.%Fe-5wt.%Si al oy. After heat treatment for 28 hours at 590 ºC, the coarse platelet or blocky Fe-rich phase in Al-5wt.%Fe-5wt.%Si al oys was granulated; the phase transformation from metastable platelet Al3FeSi and blocky Al8Fe2Si to stable Al5FeSi had occurred. With the extension of heat treatment, the Si phase coarsened gradual y.

  11. Investigation on The Properties of Fe-Si3N4 Bonded SiC Composite

    Institute of Scientific and Technical Information of China (English)

    ZHANG Yong; FENG Di; PENG Dayan

    2005-01-01

    The mechanical properties of pressureless sintering Fe-Si3N4 bonded SiC and Si3 N4 bonded SiC with same manufacture process have been compared in this paper.The oxidizing mechanism of Fe-Si3 N4 bonded SiC ceramic matrix composite has been investigated especially through TG-DSC (thermo gravimetric analysis-differential scanning calorimeter) experiment. During oxidation procedure the main reaction is the oxidation of SiC and Si3N4, SiO2 which form protecting film to prevent further oxidizing. And residual iron in the samples become Fe2 O3 and Fe3O4, the oxidation kinetics at 1100 ~ 1300℃ of re-Si3 N4 bonded SiC has been studied especially. The weight gain per unit area at initial stage changes according to beeline rule, in the middle according to conic, and in the last oxidation period follows parabola rule.

  12. Effects of SiC on Properties of Cu-SiC Metal Matrix Composites

    Science.gov (United States)

    Efe, G. Celebi; Altinsoy, I.; Ipek, M.; Zeytin, S.; Bindal, C.

    2011-12-01

    This paper was focused on the effects of particle size and distribution on some properties of the SiC particle reinforced Cu composites. Copper powder produced by cementation method was reinforced with SiC particles having 1 and 30 μm particle size and sintered at 700 °C. SEM studies showed that SiC particles dispersed in copper matrix homogenously. The presence of Cu and SiC components in composites were verified by XRD analysis technique. The relative densities of Cu-SiC composites determined by Archimedes' principle are ranged from 96.2% to 90.9% for SiC with 1 μm particle size, 97.0 to 95.0 for SiC with 30 μm particle size. Measured hardness of sintered compacts varied from 130 to 155 HVN for SiC having 1 μm particle size, 188 to 229 HVN for SiC having 1 μm particle size. Maximum electrical conductivity of test materials was obtained as 80.0% IACS (International annealed copper standard) for SiC with 1 μm particle size and 83.0% IACS for SiC with 30 μm particle size.

  13. Fabrication and measurement of devices in Si/SiGe nanomembranes

    Science.gov (United States)

    Mohr, Robert

    Silicon/silicon-germanium (Si/SiGe) heterostructures are useful as hosts for gated quantum dots. The quality of the as-grown Si/SiGe heterostructure has a large impact on the final quality of the quantum dot as a qubit host. For many years, quantum dots have been fab- ricated on strain-graded heterostructures. Commonly used strain-graded heterostructures inevitably develop plastic defects that lead to interface roughness, crosshatch, and mosaic tilt. All of these factors are sources of disorder in Si/SiGe quantum electronics. In this dissertation, I report the fabrication of Hall bars and gated quantum dots on heterostructures grown on fully elastically relaxed SiGe nanomembranes, rather than strain-graded heterostructures. I report measurements of Hall bars demonstrating the creation of two-dimensional electron gases in these structures. I report the fabrication procedures used to create pairs of Hall bars and quantum dots on individual membranes. In addition, I explain a general process flow for the creation of Si/SiGe quantum devices. I focus especially on an ion-implantation technique I implemented for the fabrication of Hall bars and quantum dots in Si/SiGe heterostructures without modulation doping layers.

  14. Quantitative analysis of hydrogen in SiO2/SiN/SiO2 stacks using atom probe tomography

    Directory of Open Access Journals (Sweden)

    Yorinobu Kunimune

    2016-04-01

    Full Text Available We have demonstrated that it is possible to reproducibly quantify hydrogen concentration in the SiN layer of a SiO2/SiN/SiO2 (ONO stack structure using ultraviolet laser-assisted atom probe tomography (APT. The concentration of hydrogen atoms detected using APT increased gradually during the analysis, which could be explained by the effect of hydrogen adsorption from residual gas in the vacuum chamber onto the specimen surface. The amount of adsorbed hydrogen in the SiN layer was estimated by analyzing another SiN layer with an extremely low hydrogen concentration (<0.2 at. %. Thus, by subtracting the concentration of adsorbed hydrogen, the actual hydrogen concentration in the SiN layer was quantified as approximately 1.0 at. %. This result was consistent with that obtained by elastic recoil detection analysis (ERDA, which confirmed the accuracy of the APT quantification. The present results indicate that APT enables the imaging of the three-dimensional distribution of hydrogen atoms in actual devices at a sub-nanometer scale.

  15. Transport properties of double-gate SiO{sub 2}-Si-SiO{sub 2} quantum well

    Energy Technology Data Exchange (ETDEWEB)

    Prunnila, Mika; Ahopelto, Jouni [VTT Information Technology, Microelectronics, P.O. Box 1208, 02044 VTT (Finland); Sakaki, Hiroyuki [University of Tokyo, Institute of Industrial Science, 4-6-1 Komaba, Meguro-ku, Tokyo 153-8503 (Japan)

    2005-05-01

    We report on fabrication and low temperature transport properties of double-gate SiO{sub 2}-Si-SiO{sub 2} quantum well with a 16.5 nm thick Si layer. The device is fabricated on a silicon-on-insulator substrate utilizing wafer bonding, which enables us to use heavily doped back gate. Transport properties of the device are characterized by low field Hall and high field magnetotransport measurements at 4.2 K and at 0.38 K, respectively. Top (back) Si-SiO{sub 2} interface peak mobility of 1.9 m{sup 2}/Vs (1.0 m{sup 2}/Vs) is measured at 4.2 K. When both gates have a (large) positive bias the Hall carrier density is observed to fall below the value of the expected total carrier density, which is interpreted to arise from the occupancy of the second sub-band in the Si well. This is confirmed by the high field magnetotransport measurements. In quantizing magnetic fields the longitudinal resistivity minima show Landau level filling factor behavior which is typical for weakly coupled bi-layers. (copyright 2005 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  16. Effects of SiC amount on phase compositions and properties of Ti3SiC2-based composites

    Institute of Scientific and Technical Information of China (English)

    蔡艳芝; 殷小玮; 尹洪峰

    2015-01-01

    The phase compositions and properties of Ti3SiC2-based composites with SiC addition of 5%−30% in mass fraction fabricated by in-situ reaction and hot pressing sintering were studied. SiC addition effectively prevented TiC synthesis but facilitated SiC synthesis. The Ti3SiC2/TiC−SiC composite had better oxidation resistance when SiC added quantity reached 20% but poorer oxidation resistance with SiC addition under 15%than Ti3SiC2/TiC composite at higher temperatures. There were more than half of the original SiC and a few Ti3SiC2 remaining in Ti3SiC2/TiC−SiC with 20% SiC addition, but all constituents in Ti3Si2/TiC composite were oxidized after 12 h in air at 1500 °C. The oxidation scale thickness of TS30, 1505.78μm, was near a half of that of T, 2715μm, at 1500 °C for 20 h. Ti3SiC2/TiC composite had a flexural strength of 474 MPa, which was surpassed by Ti3SiC2/TiC−SiC composites when SiC added amount reached 15%. The strength reached the peak of 518 MPa at 20%SiC added amount.

  17. Ge nanocrystals embedded in ultrathin Si3N4 multilayers with SiO2 barriers

    Science.gov (United States)

    Bahariqushchi, R.; Gundogdu, Sinan; Aydinli, A.

    2017-04-01

    Multilayers of germanium nanocrystals (NCs) embedded in thin films of silicon nitride matrix separated with SiO2 barriers have been fabricated using plasma enhanced chemical vapor deposition (PECVD). SiGeN/SiO2 alternating bilayers have been grown on quartz and Si substrates followed by post annealing in Ar ambient from 600 to 900 °C. High resolution transmission electron microscopy (HRTEM) as well as Raman spectroscopy show good crystallinity of Ge confined to SiGeN layers in samples annealed at 900 °C. Strong compressive stress for SiGeN/SiO2 structures were observed through Raman spectroscopy. Size, as well as NC-NC distance were controlled along the growth direction for multilayer samples by varying the thickness of bilayers. Visible photoluminescence (PL) at 2.3 and 3.1 eV with NC size dependent intensity is observed and possible origin of PL is discussed.

  18. Synthesis of nickel catalyzed Si/SiC core-shell nanowires by HWCVD

    Science.gov (United States)

    Tong Goh, Boon; Abdul Rahman, Saadah

    2014-12-01

    Si/SiC core-shell nanowires grown on glass substrates by hot-wire chemical vapor deposition were studied. Nickel was used as a catalyst to initiate the growth of these core-shell nanowires and the nanowires were grown at different deposition pressures of 0.5 and 1 mbar. The core of the nanowire was found to be a single crystalline Si. The shell of the nanowire consisted of Si nano-crystallites embedded within an amorphous SiC matrix which was attributed to a radial growth of columnar structures. The Si and SiC nano-crystallites embedded within an amorphous matrix exhibited room-temperature photoluminescence emissions in the range of 400 nm-1 μm. A vapor-solid-solid growth mechanism of these core-shell nanowires is proposed. The effects of the deposition pressure on the properties of the core-shell nanowires are also discussed.

  19. Quantum Confinement Effects in Strained SiGe/Si Multiple Quantum Wells

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    Strained SiGe/Si multiple quantum wells (MQWs) were grown by cold-wall ultrahigh vacuum chemical vapor deposition (UHV/CVD). Photoluminescence measurement was performed to study the exciton energies of strained Si0.84 Ge0.16/Si MQWs with SiGe well widths ranging from 4.2nm to 25.4nm. The confinement energy of 43meV is found in the Si0.84Ge0.16/Si MQWs with well width of 4.2nm. The confinement energy was calculated by solving the problem of a particle confined in a single finite rectangular poteintial well using one band effect mass model. Experimental and theoretical confinement energies are in good agreement

  20. A low temperature processed Si-quantum-dot poly-Si TFT nonvolatile memory device

    Institute of Scientific and Technical Information of China (English)

    Sun Wei

    2013-01-01

    This paper reports on a successful demonstration of poly-Si TFT nonvolatile memory with a much reduced thermal-budget.The TFT uses uniform Si quantum-dots (size ~10 nm and density ~1011 cm-2) asstorage media,obtained via LPCVD by flashing SiH4/H2 at 580 ℃ for 15 s on a Si3N4 surface.The poly-Si grain-enlargement step was shifted after source/drain formation.The NiSix-silicided source/drain enables a fast lateral-recrystallization,and thus grain-enlargement can be accomplished by a much reduced thermal-cycle (i.e.,550 ℃/4 h).The excellent memory characteristics suggest that the proposed poly-Si TFT Si quantum-dot memory and associated processes are promising for use in wider TFT applications,such as system-on-glass.

  1. 2D SiC/SiC composite for flow channel insert (FCI) application

    Energy Technology Data Exchange (ETDEWEB)

    Yu Haijiao [Key Laboratory of Advanced Ceramic Fibers and Composites, College of Aerospace and Materials Engineering, National University of Defense Technology, 47 Yanwachi Street, Changsha 410073 (China); Zhou Xingui, E-mail: zhouxinguilmy@163.com [Key Laboratory of Advanced Ceramic Fibers and Composites, College of Aerospace and Materials Engineering, National University of Defense Technology, 47 Yanwachi Street, Changsha 410073 (China); Wang Honglei; Zhao Shuang [Key Laboratory of Advanced Ceramic Fibers and Composites, College of Aerospace and Materials Engineering, National University of Defense Technology, 47 Yanwachi Street, Changsha 410073 (China); Wu Yican; Huang Qunying; Zhu Zhiqiang [Institute of Plasma Physics, Chinese Academy of Sciences, Hefei 230031 (China); Huang Zelan [Chongyi Zhangyuan Tungsten Co. Ltd., Chongyi 341300 (China)

    2010-12-15

    Two-dimensional (2D) silicon carbide fiber reinforced silicon carbide matrix (SiC/SiC) composite suiting for flow channel insert (FCI) application was successfully fabricated by stacking molding-precursor impregnation and pyrolysis (PIP) process. Plain-woven KD-I SiC fiber fabric was used as the reinforcement. SiC coating was deposited as the fiber/matrix interphase layer by chemical vapor deposition (CVD) technique. Mechanical, thermal and electrical properties of the 2D SiC/SiC composite were investigated. The results show that mechanical properties and through thickness thermal conductivity of the 2D KD-I/PIP SiC composite well meet the FCI application requirements; meanwhile, it seems that the electrical conductivity requirement will also be satisfied with a series of improvements.

  2. Effect of PECVD SiNx/SiOyNx-Si interface property on surface passivation of silicon wafer

    Science.gov (United States)

    Jia, Xiao-Jie; Zhou, Chun-Lan; Zhu, Jun-Jie; Zhou, Su; Wang, Wen-Jing

    2016-12-01

    It is studied in this paper that the electrical characteristics of the interface between SiOyNx/SiNx stack and silicon wafer affect silicon surface passivation. The effects of precursor flow ratio and deposition temperature of the SiOyNx layer on interface parameters, such as interface state density Dit and fixed charge Qf, and the surface passivation quality of silicon are observed. Capacitance-voltage measurements reveal that inserting a thin SiOyNx layer between the SiNx and the silicon wafer can suppress Qf in the film and Dit at the interface. The positive Qf and Dit and a high surface recombination velocity in stacks are observed to increase with the introduced oxygen and minimal hydrogen in the SiOyNx film increasing. Prepared by deposition at a low temperature and a low ratio of N2O/SiH4 flow rate, the SiOyNx/SiNx stacks result in a low effective surface recombination velocity (Seff) of 6 cm/s on a p-type 1 Ω·cm-5 Ω·cm FZ silicon wafer. The positive relationship between Seff and Dit suggests that the saturation of the interface defect is the main passivation mechanism although the field-effect passivation provided by the fixed charges also make a contribution to it. Project supported by the National High Technology Research and Development Program of China (Grant No. 2015AA050302) and the National Natural Science Foundation of China (Grant No. 61306076).

  3. p-n Junction Diodes Fabricated on Si-Si/Ge Heteroepitaxial Films

    Science.gov (United States)

    Das, K.; Mazumder, M. D. A.; Hall, H.; Alterovitz, Samuel A. (Technical Monitor)

    2000-01-01

    A set of photolithographic masks was designed for the fabrication of diodes in the Si-Si/Ge material system. Fabrication was performed on samples obtained from two different wafers: (1) a complete HBT structure with an n (Si emitter), p (Si/Ge base), and an n/n+ (Si collector/sub-collector) deposited epitaxially (MBE) on a high resistivity p-Si substrate, (2) an HBT structure where epitaxial growth was terminated after the p-type base (Si/Ge) layer deposition. Two different process runs were attempted for the fabrication of Si-Si/Ge (n-p) and Si/Ge-Si (p-n) junction diodes formed between the emitter-base and base-collector layers, respectively, of the Si-Si/Ge-Si HBT structure. One of the processes employed a plasma etching step to expose the p-layer in the structure (1) and to expose the e-layer in structure (2). The Contact metallization used for these diodes was a Cu-based metallization scheme that was developed during the first year of the grant. The plasma-etched base-collector diodes on structure (2) exhibited well-behaved diode-like characteristics. However, the plasma-etched emitter-base diodes demonstrated back-to-back diode characteristics. These back-to back characteristics were probably due to complete etching of the base-layer, yielding a p-n-p diode. The deep implantation process yielded rectifying diodes with asymmetric forward and reverse characteristics. The ideality factor of these diodes were between 1.6 -2.1, indicating that the quality of the MBE grown epitaxial films was not sufficiently high, and also incomplete annealing of the implantation damage. Further study will be conducted on CVD grown films, which are expected to have higher epitaxial quality.

  4. Abiologic silicon isotope fractionation between aqueous Si and Fe(III)-Si gel in simulated Archean seawater: Implications for Si isotope records in Precambrian sedimentary rocks

    Science.gov (United States)

    Zheng, Xin-Yuan; Beard, Brian L.; Reddy, Thiruchelvi R.; Roden, Eric E.; Johnson, Clark M.

    2016-08-01

    Precambrian Si-rich sedimentary rocks, including cherts and banded iron formations (BIFs), record a >7‰ spread in 30Si/28Si ratios (δ30Si values), yet interpretation of this large variability has been hindered by the paucity of data on Si isotope exchange kinetics and equilibrium fractionation factors in systems that are pertinent to Precambrian marine conditions. Using the three-isotope method and an enriched 29Si tracer, a series of experiments were conducted to constrain Si isotope exchange kinetics and fractionation factors between amorphous Fe(III)-Si gel, a likely precursor to Precambrian jaspers and BIFs, and aqueous Si in artificial Archean seawater under anoxic conditions. Experiments were conducted at room temperature, and in the presence and absence of aqueous Fe(II) (Fe(II)aq). Results of this study demonstrate that Si solubility is significantly lower for Fe-Si gel than that of amorphous Si, indicating that seawater Si concentrations in the Precambrian may have been lower than previous estimates. The experiments reached ˜70-90% Si isotope exchange after a period of 53-126 days, and the highest extents of exchange were obtained where Fe(II)aq was present, suggesting that Fe(II)-Fe(III) electron-transfer and atom-exchange reactions catalyze Si isotope exchange through breakage of Fe-Si bonds. All experiments except one showed little change in the instantaneous solid-aqueous Si isotope fractionation factor with time, allowing extraction of equilibrium Si isotope fractionation factors through extrapolation to 100% isotope exchange. The equilibrium 30Si/28Si fractionation between Fe(III)-Si gel and aqueous Si (Δ30Sigel-aqueous) is -2.30 ± 0.25‰ (2σ) in the absence of Fe(II)aq. In the case where Fe(II)aq was present, which resulted in addition of ˜10% Fe(II) in the final solid, creating a mixed Fe(II)-Fe(III) Si gel, the equilibrium fractionation between Fe(II)-Fe(III)-Si gel and aqueous Si (Δ30Sigel-aqueous) is -3.23 ± 0.37‰ (2σ). Equilibrium

  5. X-Ray Photoelectron Spectroscopy and Reflection High Energy Electron Diffraction of Epitaxial Growth SiC on Si(100) Using C60 and Si

    Institute of Scientific and Technical Information of China (English)

    LIU Yan-Fang; LIU Jin-Feng; XU Peng-Shou; PAN Hai-Bin

    2007-01-01

    The formation of silicon carbide upon deposition of C60 and Si on Si(100) surface at 850 ℃ is studied via x-ray photoelectron spectroscopy and reflection high energy electron diffraction (RHEED). The C 1s, O 1s and Si 2p core-level spectra and the RHEED patterns indicate the formation of 3C-SiC.

  6. Rapid synthesis of MoSi2-Si3N4 nanocomposite via reaction milling of Si and Mo powder mixture

    Institute of Scientific and Technical Information of China (English)

    Majid Abdellahi; Alireza Amereh; Hamed Bahmanpou; and Behzad Sharafati

    2013-01-01

    The nanocomposite of MoSi2-Si3N4 (molybdenum disilicide-silicon nitride) was synthesized by reaction milling of the Mo and Si powder mixture. Changing the processing parameters led to the formation of diff erent products such asα-andβ-MoSi2, Si3N4, Mo2N, and Mo5Si3 at various milling times. A thermodynamic appraisal showed that the milling of Mo32Si68 powder mixture was associated with highly exothermic mechanically induced self-sustaining reaction (MSR) between Mo and Si. The MSR took place around 5 h of milling led to the formation ofα-MoSi2 and the reaction between Si and N2 to produce Si3N4 under a nitrogen pressure of 1 MPa. By increasing the nitrogen pressure to 5 MPa, more heat is released, resulting in the dissociation of Si3N4 and the transformation ofα-MoSi2 toβ-MoSi2. Heat treatment was also performed on the milled samples and led to the formation of Mo2N and the transformation ofα-MoSi2 toβ-MoSi2 at the milling times of 10 and 40 h, respectively.

  7. The modification behaviour for Si implanted PET

    Institute of Scientific and Technical Information of China (English)

    吴瑜光; 张通和; 刘安东; 张旭; 周固

    2003-01-01

    Polyethylene terephthalate (PET) has been modified by Si ion implantation with a dose ranging from 1 × 1016 to 2 × 1017 ions /cm2 using a metal vapor vacuum arc(MEVVA)source. The surface morphology was observed by atomic force microscopy (AFM). The change in the microstructure of Si implanted PET was observed with a transmission electron microscope (TEM). It is believed that the change would improve the conductive properties and wear resistance. The electrical properties of PET have been improved via Si ion implantation. The resistivity of implanted PET decreased obviously with an increase in ion dose. When Si ion dose was 2 × 1017 cm?2, the resistivity of PET could be less than 7.9 Ω@m. The surface hardness and modulus increased obviously. The mechanical property of the implanted PET has been modified greatly. The hardness and modulus of Si implanted PET with a dose of 2 × 1017/cm2 are 12.5 and 2.45 times greater than those of pristine PET, respectively. The area of cutting groove for Si implanted PET is narrower and shallower than those of the unimplanted PET. So the wear resistance is greatly raised. In comparison with metal ion implantation, the improvement of mechanical properties is obvious in ion implantation into PET. Si ion beam modification mechanism of PET is discussed.

  8. Effect of hydrogen on passivation quality of SiN{sub x}/Si-rich SiN{sub x} stacked layers deposited by catalytic chemical vapor deposition on c-Si wafers

    Energy Technology Data Exchange (ETDEWEB)

    Thi, Trinh Cham, E-mail: s1240009@jaist.ac.jp; Koyama, Koichi; Ohdaira, Keisuke; Matsumura, Hideki

    2015-01-30

    We investigate the role of hydrogen content and fixed charges of catalytic chemical vapor deposited (Cat-CVD) SiN{sub x}/Si-rich SiN{sub x} stacked layers on the quality of crystalline silicon (c-Si) surface passivation. Calculated density of fixed charges is on the order of 10{sup 12} cm{sup −2}, which is high enough for effective field effect passivation. Hydrogen content in the films is also found to contribute significantly to improvement in passivation quality of the stacked layers. Furthermore, Si-rich SiN{sub x} films deposited with H{sub 2} dilution show better passivation quality of SiN{sub x}/Si-rich SiN{sub x} stacked layers than those prepared without H{sub 2} dilution. Effective minority carrier lifetime (τ{sub eff}) in c-Si passivated by SiN{sub x}/Si-rich SiN{sub x} stacked layers is as high as 5.1 ms when H{sub 2} is added during Si-rich SiN{sub x} deposition, which is much higher than the case of using Si-rich SiN{sub x} films prepared without H{sub 2} dilution showing τ{sub eff} of 3.3 ms. - Highlights: • Passivation mechanism of Si-rich SiN{sub x}/SiN{sub x} stacked layers is investigated. • H atoms play important role in passivation quality of the stacked layer. • Addition of H{sub 2} gas during Si-rich SiN{sub x} film deposition greatly enhances effective minority carrier lifetime (τ{sub eff}). • For a Si-rich SiN{sub x} film with refractive index of 2.92, τ{sub eff} improves from 3.3 to 5.1 ms by H{sub 2} addition.

  9. p-Cu2O/SiO x /n-SiC/n-Si memory diode fabricated with room-temperature-sputtered n-SiC and SiO x

    Science.gov (United States)

    Yamashita, Atsushi; Tsukamoto, Takahiro; Suda, Yoshiyuki

    2016-12-01

    We investigated low-temperature fabrication processes for our previously proposed pn memory diode with a p-Cu2O/SiC x O y /n-SiC/n-Si structure having resistive nonvolatile memory and rectifying behaviors suitable for a cross-point memory array with the highest theoretical density. In previous fabrication processes, n-SiC was formed by sputtering at 1113 K, and SiC x O y and p-Cu2O were formed by the thermal oxidation of n-SiC and Cu at 1073 and 473 K, respectively. In this study, we propose a pn memory diode with a p-Cu2O/SiO x /n-SiC/n-Si structure, where n-SiC and SiO x layers are deposited by sputtering at room temperature. The proposed processes enable the fabrication of the pn memory diode at temperatures of not more than 473 K, which is used for the formation of p-Cu2O. This memory diode exhibits good nonvolatile memory and rectifying characteristics. These proposed low-temperature fabrication processes are expected to expand the range of fabrication processes applicable to current LSI fabrication processes.

  10. Interstitial Functionalization in elemental Si

    Science.gov (United States)

    Kiefer, Boris; Fohtung, Edwin

    Societies in the 21st century will face many challenges. Materials science and materials design will be essential to address and master some if not all of these challenges. Semiconductors are among the most important technological material classes. Properties such as electrical transport are strongly affected by defects and a central goal continues to be the reduction of defect densities as much as possible in these compounds. Here we present results of interstitial Fe doping in elemental Si using first-principles DFT calculations. The preliminary results show that Fe will only occupy octahedral interstitial sites. The analysis of the electronic structure shows that the compounds are ferromagnetic and that a bandgap opens as interstitial Fe concentrations decrease, with a possible intermittent semi-metallic phase. The formation energy for interstitial Fe is unfavorable, as expected, by ~1.5 eV but becomes favorable as the chemical potential of Fe increases. Therefore, we expect that biasing the system with an external electrical field will lead to the formation of these materials. Thus, our results show that interstitial defects can be beneficial for the design of functionalities that differ significantly from those of the host material.

  11. Molecular Structures of Al/Si and Fe/Si Coprecipitates and the Implication for Selenite Removal.

    Science.gov (United States)

    Chan, Ya-Ting; Kuan, Wen-Hui; Tzou, Yu-Min; Chen, Tsan-Yao; Liu, Yu-Ting; Wang, Ming-Kuang; Teah, Heng-Yi

    2016-04-20

    Aluminum and iron oxides have been often used in the coagulation processes during water purification due to their unique surface properties toward anions. In the presence of silica, the coprecipitation of Al/Si or Fe/Si might decrease the efficiency of wastewater purification and reuse. In this study, surface properties and molecular structures of Al/Si and Fe/Si coprecipitates were characterized using spectroscopic techniques. Also, the selenite removal efficiency of Al/Si and Fe/Si coprecipitates in relation to their surface and structural properties was investigated. While dissolved silicate increased with increasing pH from Fe/Si coprecipitates, less than 7% of silicate was discernible from Al/Si samples over the range from acidic to alkaline conditions. Our spectroscopic results showed that the associations between Al and Si were relatively stronger than that between Fe and Si in coprecipitates. In Al/Si coprecipitates, core-shell structures were developed with AlO6/AlO4 domains as the shells and Si frameworks polymerized from the SiO2 as the cores. However, Si framework remained relatively unchanged upon coprecipitation with Fe hydroxides in Fe/Si samples. The Si core with Al shell structure of Al/Si coprecipitates shielded the negative charges from SiO2 and thereby resulted in a higher adsorption capacity of selenite than Fe/Si coprecipitates.

  12. Molecular Structures of Al/Si and Fe/Si Coprecipitates and the Implication for Selenite Removal

    Science.gov (United States)

    Chan, Ya-Ting; Kuan, Wen-Hui; Tzou, Yu-Min; Chen, Tsan-Yao; Liu, Yu-Ting; Wang, Ming-Kuang; Teah, Heng-Yi

    2016-04-01

    Aluminum and iron oxides have been often used in the coagulation processes during water purification due to their unique surface properties toward anions. In the presence of silica, the coprecipitation of Al/Si or Fe/Si might decrease the efficiency of wastewater purification and reuse. In this study, surface properties and molecular structures of Al/Si and Fe/Si coprecipitates were characterized using spectroscopic techniques. Also, the selenite removal efficiency of Al/Si and Fe/Si coprecipitates in relation to their surface and structural properties was investigated. While dissolved silicate increased with increasing pH from Fe/Si coprecipitates, less than 7% of silicate was discernible from Al/Si samples over the range from acidic to alkaline conditions. Our spectroscopic results showed that the associations between Al and Si were relatively stronger than that between Fe and Si in coprecipitates. In Al/Si coprecipitates, core-shell structures were developed with AlO6/AlO4 domains as the shells and Si frameworks polymerized from the SiO2 as the cores. However, Si framework remained relatively unchanged upon coprecipitation with Fe hydroxides in Fe/Si samples. The Si core with Al shell structure of Al/Si coprecipitates shielded the negative charges from SiO2 and thereby resulted in a higher adsorption capacity of selenite than Fe/Si coprecipitates.

  13. Electronic structure, charge distribution, and charge transfer in α- and β-Si3N4 and at the Si(111)/Si3N4(001) interface

    Science.gov (United States)

    Zhao, G. L.; Bachlechner, M. E.

    1997-02-01

    The electronic structure, charge distribution, and charge transfer in α- and β- Si3N4 and at the Si(111)/Si3N4(001) interface have been studied using a self-consistent first-principles LCAO method. The calculated charge transfer suggests that both in α- and β-phases, the ionic formula may be written as Si3+1.24N4-0.93. For the Si(111)/Si3N4(001) interface, the silicon atoms from the Si(111) side give some electrons to the N atoms of Si3N4 forming the Si-N bonds at the interface. One Si-N bond is associated with a charge transfer of about 0.31 electrons.

  14. Retrovirus-delivered siRNA

    Directory of Open Access Journals (Sweden)

    Devroe Eric

    2002-08-01

    Full Text Available Abstract Background The ability of transfected synthetic small interfering (si RNAs to suppress the expression of specific transcripts has proved a useful technique to probe gene function in mammalian cells. However, high production costs limit this technology's utility for many laboratories and experimental situations. Recently, several DNA-based plasmid vectors have been developed that direct transcription of small hairpin RNAs, which are processed into functional siRNAs by cellular enzymes. Although these vectors provide certain advantages over chemically synthesized siRNAs, numerous disadvantages remain including merely transient siRNA expression and low and variable transfection efficiency. Results To overcome several limitations of plasmid-based siRNA, a retroviral siRNA delivery system was developed based on commerically available vectors. As a pilot study, a vector was designed to target the human Nuclear Dbf2-Related (NDR kinase. Cells infected with the anti-NDR siRNA virus dramatically downregulate NDR expression, whereas control viruses have no effect on total NDR levels. To confirm and extend these findings, an additional virus was constructed to target a second gene, transcriptional coactivator p75. Conclusion The experiments presented here demonstrate that retroviruses are efficient vectors for delivery of siRNA into mammalian cells. Retrovirus-delivered siRNA provides significant advancement over previously available methods by providing efficient, uniform delivery and immediate selection of stable "knock-down" cells. This development should provide a method to rapidly assess gene function in established cell lines, primary cells, or animals.

  15. Influence of the permeability of networked primary Si on the ejection of hypereutectic Al-Si melts by centrifugation

    Science.gov (United States)

    Youn, Ji Won; Jeon, Je-Beom; Park, Jin Man; Seo, Seok Yong; Lim, Jeon Taik; Kim, Suk Jun; Kim, Ki Young

    2017-02-01

    The separation of high purity Si for solar cells from Al-Si alloy melt in the mushy zone was investigated using an advanced centrifugal technique. The efficiency of separating Si, based on the weight ratio of separated Si to Si in alloy melt, was maximized by optimizing the permeability of a porous structure of Si (Si foam.) For the optimization of the permeability, two fundamental microstructure variables, size and the solid fraction of primary Si platelets, were controlled by adjusting the Si content in the melts and the rotation start temperature, respectively. The best separation efficiency (48.3% with 3N purity) was achieved when Si content in melt was 24% and the solid fraction was 8.7%. The melt with 23% Si led to a higher separation efficiency (69.8%) for a solid fraction of 10.4%, but Al sandwiched between the Si platelets resulted in a decrease in the purity to 2N.

  16. Microstructures in Centrifugal Casting of SiCp/AlSi9Mg Composites with Different Mould Rotation Speeds

    Institute of Scientific and Technical Information of China (English)

    WANG Kai; SUN Wenju; LI Bo; XUIE Hansong; LIU Changming

    2011-01-01

    Two ingots were produced by centrifugal casting at mould rotational speeds of 600 rpm and 800 rpm using 20 vol% SiCp/AlSi9Mg composite melt, respectively. The microstructure along the radial direction of cross-sectional sample of ingots was presented. SiC particles migrated towards the external circumference of the tube, and the distribution of SiC particles became uniform under centrifugal force. Voids in 20 vol% SiCp/AlSi9Mg composite melt migrated towards the inner circumference of the tube. The quantitative analysis results indicated that not only SiC particles but also primary a phases segregated greatly in centrifugal casting resulting from the transportation behavior of constitutions with different densities in the SiCp/AlSi9Mg composite melt. In addition, the eutectic Si was broken owing to the motion of SiCp/AlSi9Mg composite melt during centrifugal casting.

  17. Wear mechanism for spray deposited Al-Si/SiCp composites under dry sliding condition

    Institute of Scientific and Technical Information of China (English)

    滕杰; 李华培; 陈刚

    2015-01-01

    Al-Si/15%SiCp (volume fraction) composites with different silicon contents were fabricated by spray deposition technique, and typical microstructures of these composites were studied by optical microscopy (OM). Dry sliding wear tests were carried out using a block-on-ring wear machine to investigate the effect of applied load range of 10−220 N on the wear and friction behavior of these composites sliding against SAE 52100 grade bearing steel. Scanning electron microscopy (SEM) and energy-dispersive X-ray microanalysis (EDAX) were utilized to examine the morphologies of the worn surfaces in order to observe the wear characteristics and investigate the wear mechanism. The results show that the wear behavior of these composites is dependent on the silicon content in the matrix alloy and the applied load. Al-Si/15%SiCp composites with higher silicon content exhibit better wear resistance in the applied load range. Under lower loads, the major wear mechanisms are oxidation wear and abrasive wear for all tested composites. Under higher loads, severe adhesive wear becomes the main wear mechanisms for Al-7Si/15%SiCp and Al-13Si/15%SiCp composites, while Al-20Si/15%SiCp presents a compound wear mechanism, consisting of oxidation, abrasive wear and adhesion wear.

  18. Completely CMOS compatible SiN-waveguide-based fiber coupling structure for Si wire waveguides.

    Science.gov (United States)

    Maegami, Yuriko; Okano, Makoto; Cong, Guangwei; Ohno, Morifumi; Yamada, Koji

    2016-07-25

    For Si wire waveguides, we designed a highly efficient fiber coupling structure consisting of a Si inverted taper waveguide and a CMOS-compatible thin SiN waveguide with an SiO2 spacer inserted between them. By using a small SiN waveguide with a 310 nm-square core, the optical field can be expanded to correspond to a fiber with a 4.0-μm mode field diameter. A coupled waveguide system with the SiN waveguide and Si taper waveguide can provide low-loss and low-polarization-dependent mode conversion. Both losses in fiber-SiN waveguide coupling and SiN-Si waveguide mode conversion are no more than 1 dB in a wide wavelength bandwidth from 1.36 μm to 1.65 μm. Through a detailed analysis of the effective refractive indices in the coupled waveguide system, we can understand mode conversion accurately and also derive guidelines for reducing the polarization dependence and for shortening device length.

  19. HREM study on stacking structure of SiGe/Si infrared detector

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    Stacking structure and defects in SiGe/P-Si infrared detector were studied by using localization high resolutionelectron microscopy (HREM). The photosensitive region in the detector consists of 3 P+-Si0.65 Ge0.35 layers and 2 UD-Si(undoped Si) layers. The interface between Si0.65 Ge0.35 and UD-Si is not sharp and has a transition zone with non-uniform contrast. The misfit stress of interface is distributed gradiently along the normal direction of the interface. Thereforethe crystal defects and serious lattice deformations on the interface have not been found. A defect area with a shape of in-verted triangle exists in the edge of photosensitive region. The main types of the defects in the area are stacking faults andmicrotwins. The stacking faults are on ( 1 11), and the thickness of the most microtwins is less than 4 interplanar spacingand the twin plane is (111). The Si0.65Ge0.35 and UD-Si layers on amorphous SiO2 layer consist of polycrystals grown byrandom nueleation, and are in wave

  20. Formation of light-emitting Si nanostructures in SiO(2) by pulsed anneals.

    Science.gov (United States)

    Kachurin, G A; Cherkova, S G; Marin, D V; Yankov, R A; Deutschmann, M

    2008-09-03

    Intense excimer laser pulses, flash lamp annealing and rapid thermal annealing were used to form Si nanocrystals in thin SiO(2) layers implanted with high doses of Si ions. The pulse durations were 20 ns, 20 ms and 1 s, respectively. Laser annealing produced light sources luminescing in the wavelength range of 400-600 nm. They were attributed to the Si clusters formed as a result of the fast segregation of Si atoms from the SiO(2) network. There were no indications of nanocrystal formation in the as-implanted layers after 20 ns laser pulses; however, nanocrystals formed when, before the laser annealing, the amorphous Si nanoprecipitates were prepared in the oxide layers. Evaluations show that the crystallization may proceed via melting. A photoluminescence band near 800 nm, typical of Si nanocrystals, was found after 20 ms and 1 s anneals. Calculations revealed that the annealing times in both cases were too short to provide the diffusion-limited crystal growth if one uses the values of stationary Si diffusivity in SiO(2). This points toward the existence of a transient rapid growth process at the very beginning of the anneals.

  1. Formation of light-emitting Si nanostructures in SiO{sub 2} by pulsed anneals

    Energy Technology Data Exchange (ETDEWEB)

    Kachurin, G A; Cherkova, S G; Marin, D V [Institute of Semiconductor Physics SO RAN, 630090 Novosibirsk (Russian Federation); Yankov, R A [Forschungszentrum Rossendorf, 01314 Dresden (Germany); Deutschmann, M [Laser Zentrum Hannover, 30419 Hannover (Germany)

    2008-09-03

    Intense excimer laser pulses, flash lamp annealing and rapid thermal annealing were used to form Si nanocrystals in thin SiO{sub 2} layers implanted with high doses of Si ions. The pulse durations were 20 ns, 20 ms and 1 s, respectively. Laser annealing produced light sources luminescing in the wavelength range of 400-600 nm. They were attributed to the Si clusters formed as a result of the fast segregation of Si atoms from the SiO{sub 2} network. There were no indications of nanocrystal formation in the as-implanted layers after 20 ns laser pulses; however, nanocrystals formed when, before the laser annealing, the amorphous Si nanoprecipitates were prepared in the oxide layers. Evaluations show that the crystallization may proceed via melting. A photoluminescence band near 800 nm, typical of Si nanocrystals, was found after 20 ms and 1 s anneals. Calculations revealed that the annealing times in both cases were too short to provide the diffusion-limited crystal growth if one uses the values of stationary Si diffusivity in SiO{sub 2}. This points toward the existence of a transient rapid growth process at the very beginning of the anneals.

  2. Formation of light-emitting Si nanostructures in SiO2 by pulsed anneals

    Science.gov (United States)

    Kachurin, G. A.; Cherkova, S. G.; Marin, D. V.; Yankov, R. A.; Deutschmann, M.

    2008-09-01

    Intense excimer laser pulses, flash lamp annealing and rapid thermal annealing were used to form Si nanocrystals in thin SiO2 layers implanted with high doses of Si ions. The pulse durations were 20 ns, 20 ms and 1 s, respectively. Laser annealing produced light sources luminescing in the wavelength range of 400-600 nm. They were attributed to the Si clusters formed as a result of the fast segregation of Si atoms from the SiO2 network. There were no indications of nanocrystal formation in the as-implanted layers after 20 ns laser pulses; however, nanocrystals formed when, before the laser annealing, the amorphous Si nanoprecipitates were prepared in the oxide layers. Evaluations show that the crystallization may proceed via melting. A photoluminescence band near 800 nm, typical of Si nanocrystals, was found after 20 ms and 1 s anneals. Calculations revealed that the annealing times in both cases were too short to provide the diffusion-limited crystal growth if one uses the values of stationary Si diffusivity in SiO2. This points toward the existence of a transient rapid growth process at the very beginning of the anneals.

  3. Microstructural characteristics of in situ Mg2Si/Al-Si composite by low superheat pouring

    Directory of Open Access Journals (Sweden)

    Wu Xiaofeng

    2013-09-01

    Full Text Available To control the morphology and size of the primary and eutectic Mg2Si phases in in situ Mg2Si/Al-Si composite and achieve a feasible and reliable technique to produce appropriate feedstock for the thixo-casting and rheo-casting of this type of material, three Al-Si matrix composites reinforced by 5wt.%, 9wt.% and 17wt.% Mg2Si with hypoeutectic, eutectic and hypereutectic compositions were prepared by the low superheat pouring (LSP process. The effects of the pouring temperature (superheat on the morphology and size distribution of primary phases (primary α-Al and Mg2Si, binary (α-Al + Mg2Si eutectic cell and eutectic Mg2Si were investigated. The experimental results show that low pouring temperature (superheat not only refines the grain structure of the primary α-Al and binary (α-Al + Mg2Si eutectic cell in three composites and promotes the formation of more non-dendritic structural semi-solid metal (SSM slurry of these phases; but also refines the primary and eutectic Mg2Si phases, which seems to be attributed to the creation of an ideal condition for the nucleation and the acquisition of a high survival of nuclei caused by the LSP process.

  4. Oxidation of TaSi2 thin films on polycrystalline Si

    Science.gov (United States)

    Nguyen Tan, T. A.; Guerfi, N.; Veuillen, J. Y.; Derrien, J.

    1990-01-01

    XPS and UPS have been used for studying the oxidation of TaSi2 films formed by annealing, under ultrahigh-vacuum, of Ta deposits (≈70Å) on polycrystalline Si. Oxidation has been carried out at room-temperature and at 700°C with an oxygen pressure of 2×10-5 mbar. Both Ta and Si react with oxygen. At room-temperature, O chemisorbs on the surface giving a mixed phase of Si suboxides and Ta oxides (TaO, TaO2 and Ta2O5). At 700°C, a very thin Ta2O5 layer (<0.1 monolayer) is formed on top of the growing SiO2 layer. In comparison with Si(111), the oxidation kinetics of TaSi2 begins with a higher transitory rate and follows afterwards the same parabolic dependence of the SiO2 thickness as a function of oxidation time. UPS spectra indicate a higher density of interface states, in comparison with that of SiO2 on Si. The XPS valence band testifies that the electronic structure of the underlying TaSi2 is preserved after oxidation. Subsequent heating of the sample leads to the progressive decomposition of SiO2, at T ≳ 750°C, while the upper Ta2O5 layer is not affected. The results are discussed in relation to thermodynamic properties of Si and Ta oxides, and compared with existing results given by macroscopic methods.

  5. Growth and photoluminescence of Si-SiOx nanowires by catalyst-free chemical vapor deposition technique

    Energy Technology Data Exchange (ETDEWEB)

    Yu, Yue [School of Physics and Nuclear Energy Engineering, Beihang University, Beijing 100191 (China); Luo, Ruiying, E-mail: ryluo@buaa.edu.cn [School of Physics and Nuclear Energy Engineering, Beihang University, Beijing 100191 (China); School of Materials Science and Engineering, Shanxi University of Technology, Hanzhong 723000 (China); Shang, Haidong [School of Physics and Nuclear Energy Engineering, Beihang University, Beijing 100191 (China)

    2016-04-15

    Graphical abstract: - Highlights: • The Si-SiOx NWs were successfully synthesized via a one-step catalyst-free CVD method using TEOS as the precursor. • The Si-SiOx NWs had a core–shell structure with Si as the inner crystalline cores and SiOx as the outer amorphous layer. • The formation of Si-SiOx NWs was implemented by the non-classical crystallization mechanism. • The Si-SiOx NWs spontaneously self-assembled from the building block of charged nanoparticles. • The Si-SiOx NWs showed their potential applications in UV emission and visible light emission devices. - Abstract: We developed a one-step catalyst-free chemical vapor deposition process to synthesize Si-SiOx nanowires using tetraethoxysilane as the precursor. Observations using scanning electron microscopy showed that the Si-SiOx nanowires were 20–50 nm in diameter and tens of microns in length. The high-resolution transmission electron microscope analysis and X-ray diffraction demonstrated that the nanowires consisted of crystal silicon and amorphous SiOx. The Si and O with an atomic ratio of the Si-SiOx NWs were 1:1.2 according to the energy dispersion X-ray spectroscope. A systematic study on the effect of the growth conditions, such as reaction temperature, the reaction time, and the TEOS vapor flow rate was performed. The formation of Si-SiOx nanowires was implemented by the non-classical crystallization mechanism. The charged nanoparticles acting as building blocks self-assembled into nanowires. The photoluminescence measurements were carried out and showed that the Si-SiOx nanowires emitted stable ultraviolet and green luminescence excited by ultraviolet light.

  6. Removal of C and SiC from Si and FeSi during ladle refining and solidification

    Energy Technology Data Exchange (ETDEWEB)

    Klevan, Ole Svein

    1997-12-31

    The utilization of solar energy by means of solar cells requires the Si to be very pure. The purity of Si is important for other applications as well. This thesis mainly studies the total removal of carbon from silicon and ferrosilicon. The decarburization includes removal of SiC particles by stirring and during casting in addition to reduction of dissolved carbon by gas purging. It was found that for three commercial qualities of FeSi75, Refined, Gransil, and Standard lumpy, the refined quality is lowest in carbon, followed by Gransil and Standard. A decarburization model was developed that shows the carbon removal by oxidation of dissolved carbon to be a slow process at atmospheric pressure. Gas stirring experiments have shown that silicon carbide particles are removed by transfer to the ladle wall. The casting method of ferrosilicon has a strong influence on the final total carbon content in the commercial alloy. Shipped refined FeSi contains about 100 ppm total carbon, while the molten alloy contains roughly 200 ppm. The total carbon out of the FeSi-furnace is about 1000 ppm. It is suggested that low values of carbon could be obtained on an industrial scale by injection of silica combined with the use of vacuum. Also, the casting system could be designed to give low carbon in part of the product. 122 refs., 50 figs., 24 tabs.

  7. Large area and depth-profiling dislocation imaging and strain analysis in Si/SiGe/Si heterostructures.

    Science.gov (United States)

    Chen, Xin; Zuo, Daniel; Kim, Seongwon; Mabon, James; Sardela, Mauro; Wen, Jianguo; Zuo, Jian-Min

    2014-10-01

    We demonstrate the combined use of large area depth-profiling dislocation imaging and quantitative composition and strain measurement for a strained Si/SiGe/Si sample based on nondestructive techniques of electron beam-induced current (EBIC) and X-ray diffraction reciprocal space mapping (XRD RSM). Depth and improved spatial resolution is achieved for dislocation imaging in EBIC by using different electron beam energies at a low temperature of ~7 K. Images recorded clearly show dislocations distributed in three regions of the sample: deep dislocation networks concentrated in the "strained" SiGe region, shallow misfit dislocations at the top Si/SiGe interface, and threading dislocations connecting the two regions. Dislocation densities at the top of the sample can be measured directly from the EBIC results. XRD RSM reveals separated peaks, allowing a quantitative measurement of composition and strain corresponding to different layers of different composition ratios. High-resolution scanning transmission electron microscopy cross-section analysis clearly shows the individual composition layers and the dislocation lines in the layers, which supports the EBIC and XRD RSM results.

  8. Preparation and Characterization of Novel Porous Fe-Si Alloys

    Institute of Scientific and Technical Information of China (English)

    WANG Jiefeng; HE Yuehui; JIANG Yao; GAO Hanyan; YANG Junsheng; GAO Lin

    2016-01-01

    Porous Fe-Si alloys with different nominal compositions ranging from Fe-10wt% Si to Fe-50wt% Si were fabricated through a reactive synthesis of Fe and Si elemental powder mixtures. The effects of Si contents on the pore structure of porous Fe-Si alloy were investigated in detail. The results showed that the open porosity, gas permeability and maximum pore size of the porous Fe-Si alloys increased with increasing Si contents, indicating that the porosity and pore size can be tailored by changing the Si contents. The pore structure parameter including the open porosity, gas permeability, maximum pore size obeyed the Hagen-Poiseuille formula with the constant G=0.035 m-1Pa-1s-1 for the reactively synthesized porous Fe-Si alloys. The mechanical property of the porous Fe-Si alloys showed applicability in the ifltration industries.

  9. Chemisorption of Au on Si(001) surface

    Institute of Scientific and Technical Information of China (English)

    Wei Shu-Yi; Wang Jian-Guang; Ma Li

    2004-01-01

    @@ The chemisorption of one monolayer of Au atoms on an ideal Si(001) surface is studied by using the self-consistent tight binding linear muffin-tin orbital method. Energies of the adsorption system of a Au atom on different sites are calculated. It is found that the most stable position is A site (top site) for the adsorbed Au atoms above the Si(001)surface. It is possible for the adsorbed Au atoms to sit below the Si(001) surface at the B1 site(bridge site), resulting in a Au-Si mixed layer. This is in agreement with the experiment results. The layer projected density of states is calculated and compared with that of the clean surface. The charge transfer is also investigated.

  10. Straight SiO_x nanorod Yjunctions

    Institute of Scientific and Technical Information of China (English)

    2009-01-01

    Novel straight silicon oxide [SiOx (1Si plate by thermal evaporation of mixed powders of silica and carbon nanofibers at 1300℃ and condensation on a Si substrate without assistance of any catalyst. The synthesized samples were characterized by means of scanning electron microscopy, transmission electron microscopy, high resolution transmission electron microscopy, and energy dispersive X-ray spectroscopy. The results suggested that the straight nanorod Y junctions are amorphous and consist only of elements Si and O, and these rods with diameters about 50―200 nm have a neat smooth surface. The growth of such silicon oxide nanorods may be a result of the second nucleation on the surface of rods causing a change in the growth direc- tion of silicon oxide nanorods developed.

  11. Half-life of 31Si

    CERN Document Server

    D'Agostino, Giancarlo; Mana, Giovanni; Oddone, Massimo

    2016-01-01

    Half-life values are widely used in nuclear chemistry to model the exponential decay of the quantified radionuclides. The analysis of existing data reveals a general lack of information on the performed experiments and an almost complete absence of uncertainty budgets. This is the situation for 31Si, the radionuclide produced via neutron capture reaction recently used to quantify trace amounts of 30Si in a sample of the silicon material highly enriched in 28Si and used for the determination of the Avogadro constant. In order to improve the quality of the now recommended 157.36(26) min value, we carried out repeated observations of the 31Si decay rate via gamma-ray spectrometry measurements. This paper reports the result we obtained, including details of the experiment and the evaluation of the uncertainty.

  12. Cu2ZnSiS4

    Directory of Open Access Journals (Sweden)

    Kimberly A. Rosmus

    2011-04-01

    Full Text Available Single crystals of Cu2ZnSiS4, dicopper(I zinc silicon tetrasulfide, have been prepared via high-temperature solid-state synthesis. Cu2ZnSiS4 was found to have the wurtz-stannite structure type, like that of Li2CdGeS4, Li2CdSnS4, and Cu2CdSiS4. Each sulfur anion is tetrahedrally coordinated by two Cu cations, one Si cation, and one Zn cation, forming a three-dimensional honeycomb structure. When viewed along the c axis, the atoms are aligned in rows in which each cation alternates with the sulfur anions.

  13. Refractive index spectral dependence, Raman and transmission spectra of high-purity $^{28}$Si, $^{29}$Si, $^{30}$Si, and $^{nat}$Si single crystals

    CERN Document Server

    Plotnichenko, V G; Kryukova, E B; Koltashev, V V; Sokolov, V O; Dianov, E M; Gusev, A V; Gavva, V A; Kotereva, T V; Churbanov, M F

    2011-01-01

    Precise measurement of the refractive index of stable silicon isotopes $^{28}$Si, $^{29}$Si, $^{30}$Si single crystals with enrichments above 99.9 at.% and a silicon single crystal $^{nat}$Si of natural isotopic composition is performed with the Fourier-transform interference refractometry method from 1.06 to more than 80 mkm with 0.1 cm$^{-1}$ resolution and accuracy of $2 \\times 10^{-5} ... 1 \\times 10^{-4}$. The oxygen and carbon concentrations in all crystals are within $5 \\times 10^{15}$ cm$^{-3}$ and the content of metal impurities is $10^{-5} ... 10^{-6}$ at.%. The peculiar changes of the refractive index in the phonon absorption region of all silicon single crystals are shown. The coefficients of generalized Cauchy dispersion function approximating the experimental refractive index values all over the measuring range are given. The transmission and Raman spectra are also studied.

  14. Si-based Nanoparticles: a biocompatibility study

    Science.gov (United States)

    Rivolta, I.; Lettiero, B.; Panariti, A.; D'Amato, R.; Maurice, V.; Falconieri, M.; Herlein, N.; Borsella, E.; Miserocchi, G.

    2010-10-01

    Exposure to silicon nanoparticles (Si-NPs) may occur in professional working conditions or for people undergoing a diagnostic screening test. Despite the fact that silicon is known as a non-toxic material, in the first case the risk is mostly related to the inhalation of nanoparticles, thus the most likely route of entry is across the lung alveolar epithelium. In the case of diagnostic imaging, nanoparticles are usually injected intravenously and Si-NPs could impact on the endothelial wall. In our study we investigated the interaction between selected Si-based NPs and an epithelial lung cell line. Our data showed that, despite the overall silicon biocompatibility, however accurate studies of the potential toxicity induced by the nanostructure and engineered surface characteristics need to be accurately investigated before Si nanoparticles can be safely used for in vivo applications as bio-imaging, cell staining and drug delivery.

  15. Si3N4-SiC材料的腐蚀性能研究

    Institute of Scientific and Technical Information of China (English)

    李杰

    2009-01-01

    利用Si3N4-SiC材料在冰晶石静态融盐电解质中的腐蚀实验研究材料的腐蚀性能,对腐蚀增重率进行记录分析,Si3N4的含量以及腐蚀时间都是影响Si3N4-SiC材料腐蚀性能的重要因素,腐蚀过程主要发生在25h前,并且随着Si3N4的含量增加,腐蚀程度越严重.

  16. The Effect of Si Morphology on Machinability of Al-Si Alloys

    Directory of Open Access Journals (Sweden)

    Muhammet Uludağ

    2015-12-01

    Full Text Available Many of the cast parts require some sort of machining like milling, drilling to be used as a finished product. In order to improve the wear properties of Al alloys, Si is added. The solubility of Si in Al is quite low and it has a crystallite type structure. It behaves as particulate metal matrix composite which makes it an attractive element. Thus, the wear and machinability properties of these type of alloys depend on the morphology of Si in the matrix. In this work, Sr was added to alter the morphology of Si in Al-7Si and Al-12Si. Cylindrical shaped samples were cast and machinability characteristics of Sr addition was studied. The relationship between microstructure and machinability was evaluated.

  17. Modification effect of lanthanum on primary phase Mg2Si in Mg-Si alloys

    Institute of Scientific and Technical Information of China (English)

    WANG Liping; GUO Erjun; MA Baoxia

    2008-01-01

    The modifying effect of La addition on primary phase Mg2Si in Mg-5Si alloys was investigated. The results showed that a proper amount of La could effectively modify the primary phase Mg2Si. Based on the present experiment, the optimal modification effect was obtained with an addition of about 0.5 wt.% La. The size of the primary phase Mg2Si was considerably reduced to 25 μm or less and the morphology was modified from a coarse dendritic shape to a polyhedral shape. However, when the addition of La increased to 0.8 wt.% or higher, the primary Mg2Si grew into a coarse dendritic morphology again. Moreover, it was found that some LaSi2 compounds were formed during solidification and the amount of the compounds appeared to increase gradually with increasing La content.

  18. Ferroelectric modulation of terahertz waves with graphene/ultrathin-Si:HfO2/Si structures

    Science.gov (United States)

    Jiang, Ran; Han, Zuyin; Sun, Weideng; Du, Xianghao; Wu, Zhengran; Jung, Hyung-Suk

    2015-10-01

    Ferroelectric-field-effect-tunable modulation of terahertz waves in graphene/Si:HfO2/Si stack structure was observed. The modulation shows distinct behaviors when the samples under different gate polarities. At a negative voltage, a transmission modulation depth up to ˜74% was present without depending on the photo illumination power, whereas, at a positive voltage, the modulation of Thz wave shows dependence on the illumination power, which is ascribed to the creation/elimination of an extra barrier in Si layer in response to the polarization in the ferroelectric Si:HfO2 layer. Considering the good compatibility of HfO2 on Si-based semiconductor process, the ferroelectricity layer of Si:HfO2 may open up an avenue for the tunable modulation of Thz wave.

  19. Light absorption mechanism in single c-Si (core)/a-Si (shell) coaxial nanowires.

    Science.gov (United States)

    Liu, W F; Oh, J I; Shen, W Z

    2011-03-25

    We have carried out detailed investigations on the light absorption mechanism in single crystalline silicon (c-Si) (core)/amorphous Si (a-Si) (shell) coaxial nanowires (NWs). Based on the Lorenz-Mie light scattering theory, we have found that the light absorption in the coaxial NWs relies on the leaky mode resonances and that the light absorption can be optimized towards photovoltaic applications when the a-Si shell thickness is about twice the c-Si core radius. The photocurrent has been found to be enhanced up to ∼ 560% compared to c-Si NWs, and to be further enhanced up to ∼ 60% by coating the nonabsorbing dielectric shells.

  20. Advanced Environmental Barrier Coatings Developed for SiC/SiC Composite Vanes

    Science.gov (United States)

    Lee, Kang N.; Fox, Dennis S.; Eldridge, Jeffrey I.; Zhu, Dongming; Bansal, Narottam P.; Miller, Robert A.

    2003-01-01

    Ceramic components exhibit superior high-temperature strength and durability over conventional component materials in use today, signifying the potential to revolutionize gas turbine engine component technology. Silicon-carbide fiber-reinforced silicon carbide ceramic matrix composites (SiC/SiC CMCs) are prime candidates for the ceramic hotsection components of next-generation gas turbine engines. A key barrier to the realization of SiC/SiC CMC hot-section components is the environmental degradation of SiC/SiC CMCs in combustion environments. This is in the form of surface recession due to the volatilization of silica scale by water vapor. An external environmental barrier coating (EBC) is a logical approach to achieve protection and long-term durability.