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Sample records for hydroxyapatite ceramic burr-hole

  1. Integration of Rabbit Adipose Derived Mesenchymal Stem Cells to Hydroxyapatite Burr Hole Button Device for Bone Interface Regeneration

    PubMed Central

    Gayathri, Viswanathan; Harikrishnan, Varma; Mohanan, Parayanthala Valappil

    2016-01-01

    Adipose Derived Mesenchymal Stem Cells, multipotent stem cells isolated from adipose tissue, present close resemblance to the natural in vivo milieu and microenvironment of bone tissue and hence widely used for in bone tissue engineering applications. The present study evaluates the compatibility of tissue engineered hydroxyapatite burr hole button device (HAP-BHB) seeded with Rabbit Adipose Derived Mesenchymal Stem Cells (ADMSCs). Cytotoxicity, oxidative stress response, apoptotic behavior, attachment, and adherence of adipose MSC seeded on the device were evaluated by scanning electron and confocal microscopy. The results of the MTT (3-(4,5-dimethylthiazol)-2,5-diphenyl tetrazolium bromide) assay indicated that powdered device material was noncytotoxic up to 0.5 g/mL on cultured cells. It was also observed that oxidative stress related reactive oxygen species production and apoptosis on cell seeded device were similar to those of control (cells alone) except in 3-day period which showed increased reactive oxygen species generation. Further scanning electron and confocal microscopy indicated a uniform attachment of cells and viability up to 200 μm deep inside the device, respectively. Based on the results, it can be concluded that the in-house developed HAP-BHB device seeded with ADMSCs is nontoxic/safe compatible device for biomedical application and an attractive tissue engineered device for calvarial defect regeneration. PMID:26880922

  2. 21 CFR 882.5250 - Burr hole cover.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ...) Identification. A burr hole cover is a plastic or metal device used to cover or plug holes drilled into the skull during surgery and to reattach cranial bone removed during surgery. (b) Classification. Class...

  3. 21 CFR 882.5250 - Burr hole cover.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ...) Identification. A burr hole cover is a plastic or metal device used to cover or plug holes drilled into the skull during surgery and to reattach cranial bone removed during surgery. (b) Classification. Class...

  4. 21 CFR 882.5250 - Burr hole cover.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ...) Identification. A burr hole cover is a plastic or metal device used to cover or plug holes drilled into the skull during surgery and to reattach cranial bone removed during surgery. (b) Classification. Class...

  5. 21 CFR 882.5250 - Burr hole cover.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ...) Identification. A burr hole cover is a plastic or metal device used to cover or plug holes drilled into the skull during surgery and to reattach cranial bone removed during surgery. (b) Classification. Class...

  6. 21 CFR 882.5250 - Burr hole cover.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ...) Identification. A burr hole cover is a plastic or metal device used to cover or plug holes drilled into the skull during surgery and to reattach cranial bone removed during surgery. (b) Classification. Class...

  7. Hydroxyapatite ceramics from hydrothermally prepared powders

    SciTech Connect

    Lin, C.H.; Huang, C.W.; Chang, S.C.

    1994-12-31

    Hydroxyapatite (Ca{sub 5}(PO{sub 4}){sub 3}(OH)) is an effective material for artificial human bone production. Hydroxyapatite powders were hydrothermally produced in this work by reacting Ca(OH){sub 2} with Na{sub 3}PO{sub 4}{center_dot}12H{sub 2}O in an autoclave at various temperature and for various times. The particle size of hydroxyapatite was observed to be very fine, uniform, around 50 nm, as well as independent of reaction time. The hydroxyapatite powders were compacted and sintered at various temperatures for 2 hrs. The density, grain size, and hardness of the hydroxyapatite ceramics were measured and compared with those of the hydroxyapatite ceramics produced by the powders from the commercial source. The hydroxyapatite ceramics from the hydrothermal powders were found to have a higher density, smaller grain size, and higher hardness. After the hydroxyapatite ceramics were dipped in a simulated biological body liquid for 10 days, the density and hardness of the hydroxyapatite ceramics from the hydrothermal powders were less deteriorated than those of the hydroxyapatite ceramics from the commercial powder.

  8. Comparative study between cortical bone graft versus bone dust for reconstruction of cranial burr holes

    PubMed Central

    Worm, Paulo V.; Ferreira, Nelson P.; Faria, Mario B.; Ferreira, Marcelo P.; Kraemer, Jorge L.; Collares, Marcus V. M.

    2010-01-01

    Background: As a consequence of the progressive evolution of neurosurgical techniques, there has been increasing concern with the esthetic aspects of burr holes. Therefore, the objective of this study was to compare the use of cortical bone graft and bone dust for correcting cranial deformities caused by neurosurgical trephines. Methods: Twenty-three patients were enrolled for cranial burr hole reconstruction with a 1-year follow-up. A total of 108 burr holes were treated; 36 burr holes were reconstructed with autogenous cortical bone discs (33.3%), and the remaining 72 with autogenous wet bone powder (66.6%). A trephine was specifically designed to produce this coin-shaped bone plug of 14 mm in diameter, which fit perfectly over the burr holes. The reconstructions were studied 12 months after the surgical procedure, using three-dimensional quantitative computed tomography. Additionally, general and plastic surgeons blinded for the study evaluated the cosmetic results of those areas, attributing scores from 0 to 10. Results: The mean bone densities were 987.95 ± 186.83 Hounsfield units (HU) for bone fragment and 473.55 ± 220.34 HU for bone dust (P < 0.001); the mean cosmetic scores were 9.5 for bone fragment and 5.7 for bone dust (P < 0.001). Conclusions: The use of autologous bone discs showed better results than bone dust for the reconstruction of cranial burr holes because of their lower degree of bone resorption and, consequently, better cosmetic results. The lack of donor site morbidity associated with procedural low cost qualifies the cortical autograft as the first choice for correcting cranial defects created by neurosurgical trephines. PMID:21206899

  9. Remote Cerebellar Haemorrhage after Burr Hole Drainage of Chronic Subdural Haematoma: A Case Report

    PubMed Central

    Karaarslan, Numan; Gök, Sevki; Soyalp, Celaleddin

    2016-01-01

    Remote cerebellar haemorrhage (RCH) is an unusual complication of supratentorial neurosurgical procedures. Even the rarer is cerebellar haemorrhage occurring after supratentorial burr hole drainage of Chronic Subdural Haematoma (CSDH). The exact mechanism is still unclear despite some possible causative factors such as rapid evacuation of haematoma and overdrainage of CSF (Cerebrospinal Fluid). We report a 80-year-old male patient who developed cerebellar haemorrhage after burr hole drainage of left frontoparietal chronic subdural haematoma and discuss the possible aetiological mechanisms through the review of the current literature. PMID:27437296

  10. Comparison of the Outcomes and Recurrence with Three Surgical Techniques for Chronic Subdural Hematoma: Single, Double Burr Hole, and Double Burr Hole Drainage with Irrigation

    PubMed Central

    Jang, Kyoung-Min; Hwang, Sung-Nam; Park, Yong-Sook; Nam, Taek-Kyun

    2015-01-01

    Objective Chronic subdural hematoma (CSDH), a disease commonly encountered by neurosurgeons, is treated by burr hole drainage (BHD). However, the optimal surgical technique among the three types of BHD has not been determined. Methods We conducted a retrospective study on BHD performed on 93 patients who were diagnosed with CSDH. The subjects were divided into three groups based on the surgical technique performed: single BHD without irrigation (Group A, n=31), double BHD without irrigation (Group B, n=32), and double BHD with irrigation (Group C, n=30). The clinical factors, radiological factors and recurrences were compared between the three groups. Moreover, independent factors affecting the recurrence were analyzed. Results The change in hematoma thickness was 29.77±7.94%, 49.73±12.87%, and 75.29±4.32% for Group A, B, and C, respectively, while the change in midline shift was 40.81±15.47%, 51.78±10.94%, and 56.16±16.16%, respectively. Thus, Group C showed the most effective for resolution of hematoma and midline shift (p<0.05). Group A, B, and C had 12 cases (38.7%), 8 cases (25.0%), and 3 cases (10.0%) of recurrences, respectively. Group C had a statistically significantly fewer recurrence rate than Group A (p<0.05). Double burr hole, irrigation, and coagulopathy were each identified as independent factors that reduce recurrence (p<0.05). Conclusion Among the three techniques, the double BHD with saline irrigation resulted in the fewest recurrences. It is probably the most effective technique for preventing the recurrence of CSDH. PMID:27169069

  11. Tiger hide appearance: Impaction and prolapse of brain parenchyma through burr holes after evacuation of bilateral chronic subdural hematoma: A rare case report

    PubMed Central

    Jaiswal, Manish; Gandhi, Ashok; Purohit, Devendra; Mittal, R. S.

    2016-01-01

    Burr hole evacuation of chronic subdural hematoma (SDH) with or without drainage system is the most common surgical method among various techniques. There are various complications of burr hole drainage evacuation of chronic SDH, but there is no case report regarding impaction and prolapse of brain parenchyma through burr hole as a complication. Herewith, we are reporting a case of bilateral chronic SDH with prolapse of brain parenchyma through burr holes. Magnetic resonance imaging (MRI) of brain showed a characteristic look and we named it “Tiger hide appearance”. We failed to find such characteristic appearance in MRI brain on reviewing the available literature. PMID:27366284

  12. Tiger hide appearance: Impaction and prolapse of brain parenchyma through burr holes after evacuation of bilateral chronic subdural hematoma: A rare case report.

    PubMed

    Jaiswal, Manish; Gandhi, Ashok; Purohit, Devendra; Mittal, R S

    2016-01-01

    Burr hole evacuation of chronic subdural hematoma (SDH) with or without drainage system is the most common surgical method among various techniques. There are various complications of burr hole drainage evacuation of chronic SDH, but there is no case report regarding impaction and prolapse of brain parenchyma through burr hole as a complication. Herewith, we are reporting a case of bilateral chronic SDH with prolapse of brain parenchyma through burr holes. Magnetic resonance imaging (MRI) of brain showed a characteristic look and we named it "Tiger hide appearance". We failed to find such characteristic appearance in MRI brain on reviewing the available literature. PMID:27366284

  13. "Rabbit Ear" scalp deformity caused by massive subdural effusion in infant following bilateral burr-hole drainage.

    PubMed

    Satyarthee, Guru Dutta; Pankaj, Dawar; Sharma, B S

    2013-09-01

    Subdural effusion (SDE) in an infant is a rare clinical scenario, which may be secondary to a variety of etiologies. Massive SDE is an extremely rare complication of head injury. It usually runs a self-limiting course. Though neurosurgical intervention is occasionally needed, different methods of surgical procedure for management includes burr-hole alone, burr-holes with subdural drain placement, twist drill craniotomy with drain and even craniotomy. The authors report a rare case of progressive massive SDE, which despite bilateral burr-hole placement and drainage failed and presented with visual deterioration and massive bulge of scalp at burr-hole sites producing rabbit ear sign in a 10 month old infant. Ultimately cystoperitoneal shunt was carried out in a desperate attempt to prevent impending rupture of scalp sutures at sites of previous burr-hole placement. Astonishingly not only complete resolution of hygroma, but visual recovery also took place. Patient is doing well at 6 months following shunt with regaining normal vision and appropriate developmental milestones. A magnetic resonance imaging scan of brain at last follow-up revealed mild ventriculomegaly with subduro-peritoneal shunt in situ and rest of brain was unremarkable. Such cases have not been reported in literature until date. PMID:24470822

  14. Recurrence of the Chronic Subdural Hematoma after Burr-Hole Drainage with or without Intraoperative Saline Irrigation

    PubMed Central

    Kim, Dong Hwan; Kim, Hwan Soo; Choi, Hyuk Jin; Han, In Ho; Cho, Won Ho

    2014-01-01

    Objective Although standard method has not been established for the chronic subdural hematoma (CSDH), burr-hole trephination and closed system drainage with or without irrigation has been widely accepted as the treatment of choice. The aim of this study is to analysis the post-operative recurrence rates after burr-hole trephination of the CSDH according to the conduction of irrigation. Methods We retrospectively reviewed 184 patients with CSDH who underwent surgical treatment between January 2009 and December 2013. And 152 patients fulfilled the inclusion criteria as follows: 1) CSDH diagnosed on computed tomography (CT), 2) unilateral hematoma, 3) burr-hole trephination with closed system drainage, and 4) follow-up CT for at least 3 months. Those patients were divided into two groups. Group A (n=38) underwent burr-hole trephination without irrigation, and Group B (n=114), burr-hole trephination with saline irrigation. Results The overall post-operative recurrence rate was 19.1% (n=29) in this study. The majority of recurrence showed in Group B. Twenty-eight patients (24.6%) of Group B had recurrence and only 1 patient (2.6%) of Group A showed recurrence. The recurrence rate was significantly higher in Group B compared with Group A (p=0.003). Another affecting factor for the recurrence was the amount of postoperative pneumocephalus (p=0.02). No catastrophic complications were found in postoperative course. Conclusion Although there was no difference of clinical outcome in both groups, the recurrence rate was higher in saline irrigation group compared with no irrigation group. We suggest that saline irrigation procedure be reserved only for selected cases in CSDH burr-hole surgery. PMID:27169042

  15. Comparison of Irrigation versus No Irrigation during Burr Hole Evacuation of Chronic Subdural Hematoma.

    PubMed

    Iftikhar, Muzna; Siddiqui, Usman Tariq; Rauf, Mohammad Yaseen; Malik, Ali Osama; Javed, Gohar

    2016-09-01

    Objective To compare the results of the use of irrigation versus no irrigation during burr hole evacuation of chronic subdural hematoma (CSDH). Methodology The study was a retrospective chart review of those patients who underwent burr hole evacuation of CSDH during a period of 5 years. Cases were divided into two groups based on the use of irrigation during surgery. A subdural drain was placed in all patients (i.e., in both the irrigation and no-irrigation groups) and removed 24 to 48 hours postoperatively. Results The total sample size was 56, of which 34 patients were in the irrigation group and 22 in the no-irrigation group. Recurrence rate was 17.6% in the irrigation group and 9.1% in the no-irrigation group (p = 0.46). Systemic complications were predominantly cardiac related in the no-irrigation group compared with respiratory complications in the irrigation group. The irrigation group had a mortality rate of 5.9% compared with 4.5% in the no-irrigation group (p = 0.66). Conclusion No statistically significant difference was found between the two groups in terms of recurrence or mortality. PMID:27123748

  16. Gradient porous hydroxyapatite ceramics fabricated by freeze casting method

    NASA Astrophysics Data System (ADS)

    Zuo, Kai-hui; zhang, Yuan; Jiang, Dongliang; Zeng, Yu-Ping

    2011-04-01

    By controlling the cooling rates and the composition of slurries, the gradient porous hydroxyapatite ceramics are fabricated by the freeze casting method. According to the different cooling rate, the pores of HAP ceramics fabricated by gradient freeze casting are divided into three parts: one is lamellar pores, another is column pore and the last one is fine round pores. The laminated freeze casting is in favour of obtaining the gradient porous ceramics composed of different materials and the ceramics have unclear interfaces.

  17. [A Case of Organizing Chronic Subdural Hematoma Treated with Endoscopic Burr-Hole Surgery Using a Curettage and Suction Technique].

    PubMed

    Miki, Koichi; Oshiro, Shinya; Koga, Takaomi; Inoue, Tooru

    2016-09-01

    A 70-year-old man presented to our hospital because of difficulty with discrete movement of the right upper limb and dysarthria. Computed tomography(CT)of the head revealed a chronic subdural hematoma(CSDH)on the left side. The patient underwent single burr-hole irrigation and drainage on the same day. In addition to the burr hole, a cross-shaped dural incision was made which revealed a thick outer membrane and solidified hematoma. We removed as much of the clotted hematoma as possible using a curved suction tube under neuroendoscopy. The postoperative CT revealed that the hematoma was partially removed and the mass effect was reduced. As a result, the patient's neurological deficits improved. We reached a diagnosis of organizing CSDH following histologic examination of the removed hematoma that showed inflammatory cell infiltration and multiplication of fibroblasts. Neuroendoscopic hematoma evacuation via a burr hole is minimally invasive and may be a useful procedure in the treatment of some cases of organizing CSDH. PMID:27605476

  18. Dissolution studies of hydroxyapatite and glass-reinforced hydroxyapatite ceramics

    SciTech Connect

    Queiroz, A.C.; Santos, J.D.; Monteiro, F.J.; Prado da Silva, M.H

    2003-03-15

    In the continuous agitation assays, glass-reinforced hydroxyapatite (GR-HA) was shown to form a calcium phosphate (CaP) layer, but hydroxyapatite (HA) only formed dispersed precipitates. The formation of this layer was first detected on the GR-HA with a 7.5% glass addition (7.5 GR-HA) after only 3 days of immersion in simulated body fluid (SBF). The time required for layer formation decreased as the amount of glass added to the HA increased. The dissolution rate of the materials followed a similar pattern, i.e. the dissolution rate for GR-HA was higher than for HA, and increased with the addition of glass. The immersion of 7.5 GR-HA in water showed almost linear dissolution kinetics over the immersion periods (3, 7, 15, 30 and 60 days). The concentration of calcium ions in solution and the scanning electron microscopy (SEM) analysis of the 7.5 GR-HA specimens immersed in water and in SBF revealed a clear competition between the material dissolution and the precipitation of a CaP phase. Fourier transformed infrared spectroscopy with alternated total reflectance (FTIR-ATR) analysis indicated that the CaP phase that formed during longer immersion times (30 and 60 days) could be a carbonate-substituted CaP precipitate. As expected from previous work, the GR-HA behavior in terms of its in vitro bioactivity is higher than HA because a homogeneous CaP layer is formed and the precipitation occurs faster. From the dissolution test and in accordance with the chemical composition of the samples, GR-HA was more soluble than HA.

  19. Fracture toughness of hydroxyapatite/mica composite, packed hydroxyapatite, alumina ceramics, silicon nitride and -carbide.

    PubMed

    Nordström, E G; Yokobori, A T; Yokobori, T; Aizawa, Y

    1998-01-01

    By using the fracture toughness estimation method based on two-dimensional map, it was found that the ductility of the high porosity hydroxyapatite/mice composite was comparable with silicon carbide. It was measured to be higher than that of packed hydroxyapatite. Alumina ceramics with more than 96% aluminium oxide showed a higher fracture toughness than the composite material. When bending strength was compared, the strength of the composite was two or three times lower than that of packed hydroxyapatite and much lower than the other studied materials. The composite material showed high porosity, which in turn gives it a lower bending strength. However, the high porosity is more favourable for biocompatibility. PMID:9713684

  20. Influence of Barium Hexaferrite on Magnetic Properties of Hydroxyapatite Ceramics.

    PubMed

    Jarupoom, P; Jaita, P

    2015-11-01

    Hydroxyapatite (HA) powders was derived from natural bovine bone by sequence of thermal processes. The barium hexaferrite (BF) find magnetic powders were added into HA powders in ratio of 1-3 vol.%. The HA-BF ceramics were prepared by a solid state reaction method and sintered at 1250 degrees C for 2 h. Effects of BF additive on structural, physical and magnetic properties of HA ceramics were investigated. X-ray diffraction revealed that all HA-BF samples showed a main phase of high purity hydroxyapatite [Ca10(PO4)6(OH)2] with calcium and phosphate molar ratio of 1.67. The addition of BF into HA inhibited grain growth and caused an improvement of mechanical properties. The M-H hysteresis loops also showed an improvement in magnetic behavior for higher content of BF. Moreover, in vitro bioactivity test indicated that the 2-3 vol.% sample may be suitable for biological applications. PMID:26726671

  1. Burr-hole Irrigation with Closed-system Drainage for the Treatment of Chronic Subdural Hematoma: A Meta-analysis

    PubMed Central

    XU, Chen; CHEN, Shiwen; YUAN, Lutao; JING, Yao

    2016-01-01

    There is controversy among neurosurgeons regarding whether irrigation or drainage is necessary for achieving a lower revision rate for the treatment of chronic subdural hematoma (CSDH) using burr-hole craniostomy (BHC). Therefore, we performed a meta-analysis of all available published reports. Multiple electronic health databases were searched to identify all studies published between 1989 and June 2012 that compared irrigation and drainage. Data were processed by using Review Manager 5.1.6. Effect sizes are expressed as pooled odds ratio (OR) estimates. Due to heterogeneity between studies, we used the random effect of the inverse variance weighted method to perform the meta-analysis. Thirteen published reports were selected for this meta-analysis. The comprehensive results indicated that there were no statistically significant differences in mortality or complication rates between drainage and no drainage (P > 0.05). Additionally, there were no differences in recurrence between irrigation and no irrigation (P > 0.05). However, the difference between drainage and no drainage in recurrence rate reached statistical significance (P < 0.01). The results from this meta-analysis suggest that burr-hole surgery with closed-system drainage can reduce the recurrence of CSDH; however, irrigation is not necessary for every patient. PMID:26377830

  2. A single burr hole approach for direct transverse sinus cannulation for the treatment of a dural arteriovenous fistula

    PubMed Central

    Caplan, Justin M; Kaminsky, Ian; Gailloud, Philippe; Huang, Judy

    2014-01-01

    A 55-year-old woman with a symptomatic Borden II/Cognard IIa+b transverse sinus dural arteriovenous fistula underwent an attempted percutaneous transvenous embolization which was ultimately not possible given the fistula anatomy. She then underwent a partial percutaneous transarterial embolization but the fistula recurred. Given the failed percutaneous interventions, the patient underwent a combined open surgical/transvenous embolization using neuronavigation and a single burr hole craniectomy. She has remained symptom free for 3 months. This case report illustrates the feasibility of combining minimally invasive open surgical access to allow for direct venous cannulation for endovascular embolization of a dural arteriovenous fistula when traditional percutaneous methods are not an option. PMID:24398868

  3. Continuous delivery of azidothymidine by hydroxyapatite or tricalcium phosphate ceramics.

    PubMed

    Cannon, M R; Bajpai, P K

    1995-01-01

    A ceramic drug delivery system was developed for continuous release of azidothymidine (AZT). Tricalcium phosphate (TCP) and hydroxyapatite (HA) ceramics were used to fabricate ceramic devices. Each group of devices consisted of three replicates. Ceramic and AZT mixtures were compressed at a load of 3000 lbs in a 10 mm diameter die using a hydraulic press. For in vitro studies, vitamin E oil was incorporated in six different ratios in devices containing HA (500 mg) and AZT (250 mg). Each device was suspended in phosphate buffered saline (pH 7.4). Devices containing oil released AZT in significantly lower amounts than devices containing no oil. In vivo studies were conducted with devices composed of homogeneous mixtures of 250 mg AZT and 500 mg TCP with and without vitamin E oil in the following combinations: AZT and TCP (Group I), Oil saturated TCP and AZT (Group II), and AZT pellet inserted in an oil saturated TCP shell (Group III). These devices were implanted subcutaneously in Sprague Dawley rats for two weeks. Group II and III devices delivered AZT at a significantly lower rate than Group I devices. Results of both studies suggest that treatment of ceramic devices with oil decreases the release rate and prolongs the delivery of AZT. PMID:7654955

  4. Use of Subperiosteal Drain Versus Subdural Drain in Chronic Subdural Hematomas Treated With Burr-Hole Trepanation: Study Protocol for a Randomized Controlled Trial

    PubMed Central

    Lutz, Katharina; Schaedelin, Sabine; Mariani, Luigi; Fandino, Javier

    2016-01-01

    Background Chronic subdural hematoma (cSDH) is one of the most frequent neurosurgical conditions affecting elderly people and is associated with substantial morbidity and mortality. The use of a subdural drain (SDD) after burr-hole trepanation for cSDH was proven to reduce recurrence and mortality at 6 months. To date in neurosurgery practice, evidence-based guidelines on whether an SDD or subperiosteal drain (SPD) should be used do not exist. Currently both methods are being practiced depending on the institute and/or the practicing neurosurgeon. Objective The aim of this study is to compare the reoperation rates after burr-hole trepanation and insertion of an SPD or SDD in patients with cSDH. Methods This is a prospective, noninferiority, multicenter, randomized controlled trial designed to include 220 patients over the age of 18 years presenting with a symptomatic cSDH verified on cranial computed tomography or magnetic resonance imaging who are to undergo surgical evacuation with burr-hole trepanation. After informed consent is obtained, patients are randomly allocated to an SPD or SDD group. The primary endpoint is recurrence indicating a reoperation within 12 months. Results This research is investigator-initiated and has received ethics approval. Patient recruitment started in April 2013, and we expect all study-related activities to be completed by the end of 2016 or beginning of 2017. Conclusions To date, evidence-based recommendations concerning the operative treatment of cSDH are sparse. Results of this research are expected to have applications in evidence-based practice for the increasing number of patients suffering from cSDH and possibly lead to more efficient treatment of this disease with fewer postoperative complications. Trial Registration ClinicalTrials.gov NCT01869855; https://clinicaltrials.gov/ct2/show/NCT01869855 (Archived by WebCite at http://www.webcitation.org/6fNK4Jlxk) PMID:27059872

  5. Which should be appropriate surgical treatment for subtentorial epidural empyema? Burr-hole evacuation versus decompressive craniectomy: Review of the literature with a case report

    PubMed Central

    Köksal, Vaner; Özgür, Abdulkadir; Terzi, Suat

    2016-01-01

    Subtentorial empyema is a rare intracranial complication of chronic otitis media. Moreover, if not correctly treated, it is a life-threatening infection. Epidural and subdural empyemas on subtentorial space have different effects. This difference is not mentioned in literature. If the distinction can be made, surgical treatment method will be different, and the desired surgical treatment may be less minimal invasive. A 26-year-old male patient was found to have developed epidural empyema in the subtentorial space. We performed a burr-hole evacuation in this case because there was low cerebellar edema, Also, the general condition of the patient was good, the empyema was a convex image on the lower surface of tentorium on magnetic resonance images, and when the dura mater base is reached during mastoidectomy for chronic otitis media, we were observed to drain a purulent material through the epidural space. After 10 days from surgery increased posterior fossa edema caused hydrocephalus. Therefore, ventriculoperitoneal shunt insertion was performed. The patient fully recovered and was discharged after 6 weeks. Complete correction in the posterior fossa was observed by postoperative magnetic resonance imaging. Burr-hole evacuation from inside of the mastoidectomy cavity for subtentorial epidural empyema is an effective and minimal invasive surgical treatment. PMID:27057210

  6. In situ hydroxyapatite nanofiber growth on calcium borate silicate ceramics in SBF and its structural characteristics.

    PubMed

    Pu, Yinfu; Huang, Yanlin; Qi, Shuyun; Chen, Cuili; Seo, Hyo Jin

    2015-10-01

    A novel calcium silicate borate Ca11Si4B2O22 ceramic was firstly prepared by the conventional solid-state reaction. In vitro hydroxyapatite mineralization was investigated by soaking the ceramics in simulated body fluid (SBF) solutions at body temperature (37 °C) for various time periods. Scanning electron microscopy (SEM) and X-ray diffraction analysis (XRD) measurements were applied to investigate the samples before and after the immersion of ceramics in SBF solution. The elemental compositions of a hydroxyapatite layer on the ceramics during the mineralization were confirmed by X-ray energy-dispersive spectra (EDS). Meanwhile, the bending strength and elastic modulus of Ca11Si4B2O22 ceramics were also measured, which indicate that the biomaterials based on Ca11Si4B2O22 ceramics possess bioactivity and might be a potential candidate as biomaterials for hard tissue repair. The bioactive mineralization ability was evaluated on the base of its crystal structural characteristics, i.e., silanol (Si-OH) and B-OH groups can be easily induced on the surface of Ca11Si4B2O22 ceramics soaked in SBF solutions. PMID:26117746

  7. Effects of rheological properties on ice-templated porous hydroxyapatite ceramics.

    PubMed

    Zhang, Yan; Zhou, Kechao; Bao, Yinxiang; Zhang, Dou

    2013-01-01

    Freeze casting of aqueous suspension was investigated as a method for fabricating hydroxyapatite (HA) porous ceramics with lamellar structures. The rheological properties of HA suspensions employed in the ice-templated process were investigated systematically. Well aligned lamellar pores and dense ceramic walls were obtained successfully in HA porous ceramics with the porosity of 68-81% and compressive strength of 0.9-2.4 MPa. The results exhibited a strong correlation between the rheological properties of the employed suspensions and the morphology and mechanical properties of ice-templated porous HA ceramics, in terms of lamellar pore characteristics, porosities and compressive strengths. The ability to produce aligned pores and achieve the manipulation of porous HA microstructures by controlling the rheological parameters were demonstrated, revealing the potential of the ice-templated method for the fabrication of HA scaffolds in biomedical applications. PMID:25428079

  8. Study on the neotype zirconia's implant coated nanometer hydroxyapatite ceramics

    NASA Astrophysics Data System (ADS)

    Zhu, J. W.; Yang, D. W.

    2007-07-01

    In recent years, biologic ceramics is a popular material of implants and bioactive surface modification of dental implant became a research emphasis, which aims to improve bioactivity of implants materials and acquire firmer implants-bone interface. The zirconia ceramic has excellent mechanical properties and nanometer HA ceramics is a bioceramic well known for its bioactivity, therefore, nanometer HA ceramics coating on zirconia, allows combining the excellent mechanical properties of zirconia substrates with its bioactivity. This paper shows a new method for implant shape design and bioactive modification of dental implants surface. Zirconia's implant substrate was prepared by sintered method, central and lateral tunnels were drilled in the zirconia hollow porous cylindrical implants by laser processing. The HA powders and needle-like HA crystals were made by a wet precipitation and calcining method. Its surface was coated with nanometer HA ceramics which was used brush HA slurry and vacuum sintering. Mechanical testing results revealed that the attachment strength of nanometer HA ceramics coated zirconia samples is high. SEM and interface observation after inserted experiment indicated that calcium and phosphor content increased and symmetrically around coated implant-bone tissue interface. A significantly higher affinity index was demonstrated in vivo by histomorphometric evaluation in coated versus uncoated implants. SEM analysis demonstrated better bone adhesion to the material in coated implant at any situation. In addition, the hollow porous cylindrical implant coated with nanometer HA ceramics increase the interaction of bone and implant, the new bone induced into the surface of hollow porous cylindrical implant and through the most tunnels filled into central hole. The branch-like structure makes the implant and bone a body, which increased the contact area and decreased elastic ratio. Therefore, the macroscopical and microcosmic nested structure of

  9. Densification Process of OH Controlled Hydroxyapatite Ceramics by Spark Plasma Sintering

    SciTech Connect

    Kawagoe, D.; Koga, Y.; Ishida, E. H.; Ioku, K.

    2006-05-15

    Calcium hydroxyapatite, Ca10(PO4)6(OH)2:HA, is the inorganic principle component of natural bones and teeth. It has been already suggested that the amount of OH ion in the crystal structure of HA is closely related to the biocompatibility. The amount of OH ion in current HA, however, has not been controlled. In order to prepare more functional HA ceramics, the amount of OH ion must be controlled. In this study, HA ceramics with different OH amount were prepared from fine HA crystals by spark plasma sintering (SPS). In order to reveal the ideal sintering conditions for preparation of transparent ceramics, densification process on SPS was investigated. The samples were pressed uniaxialy under 60 MPa, and then they were heated by SPS at 800 deg. C, 900 deg. C and 1000 deg. C for 10 min with the heating rate of 25 deg. C{center_dot}min-1. The quantity of OH ion in HA ceramics sintered by SPS was decreased with increasing temperature of sintering. Transparent HA ceramics were prepared by SPS at 900 deg. C and 1000 deg. C. In analysis of the densification behavior during sintering of HA by SPS, dominant sintering mechanism was plastic flow of densification. Transparent ceramics should be the most suitable materials to investigate the interface between human cells and ceramics.

  10. Design of Natural Hydroxyapatite as bio-composite ceramics (HAP): Experimental and Numerical Study

    NASA Astrophysics Data System (ADS)

    Belghazi, Z.; Katundi, D.; Ayari, F.; Bayraktar, E.

    2011-01-01

    Hydroxyapatite (HAP—Ca10(PO4)6 (OH)2), which exhibits excellent biocompatibility in the body, is one of the most widely used bioactive ceramics for biomedical applications. Along with the ability to carry the load, one of the most important properties of materials used for bone replacement is biocompatibility. In fact, HAP is a bioactive material and it can incorporate into bone structures, supporting bone in-growth without breaking down or dissolving, and it interacts with the living tissue due to the presence of free calcium and phosphate compounds. Generally, Al2O3 powder is added to HAP powder in order to obtain high fracture toughness. Al2O3 has good mechanical properties as compared with HAP, and exhibits extremely high stability with human tissues [1-6]. In this paper, the effect of microwave sintering temperature on the relative density, hardness, and phase purity of compacted bovine Hydroxyapatite (BHA) powder was reported. This research is a comprehensive attempt to develop Hydroxyapatite bio composite ceramics reinforced with alumina—Al2O3, pure titanium and pure pulverised boron powder. A Finite Element (FEM) analysis is also used for modelling to simulate the macroscopic behaviour of this material, taking into account the relevant microscopic scales.

  11. Polarization-induced surface charges in hydroxyapatite ceramics

    NASA Astrophysics Data System (ADS)

    Horiuchi, N.; Nakaguki, S.; Wada, N.; Nozaki, K.; Nakamura, M.; Nagai, A.; Katayama, K.; Yamashita, K.

    2014-07-01

    Calcium hydroxyapatite (HAp; Ca10(PO4)6(OH)2) is a well-known biomaterial that is the main inorganic component of bones and teeth. Control over the surface charge on HAp would be a key advance in the development of the material for tissue engineering. We demonstrate here that surface charge can be induced by an electrical poling process using the Kelvin method. Positive and negative charges were induced on the HAp surface in response to the applied electric field in the poling process. The surface charging is attributed to dipole polarization that is homogeneously distributed in HAp. Additionally, the surface charging is considered to originate from the organization of OH- ions into a polar phase in the structure.

  12. Porous biomorphic silicon carbide ceramics coated with hydroxyapatite as prospective materials for bone implants.

    PubMed

    Gryshkov, Oleksandr; Klyui, Nickolai I; Temchenko, Volodymyr P; Kyselov, Vitalii S; Chatterjee, Anamika; Belyaev, Alexander E; Lauterboeck, Lothar; Iarmolenko, Dmytro; Glasmacher, Birgit

    2016-11-01

    Porous and cytocompatible silicon carbide (SiC) ceramics derived from wood precursors and coated with bioactive hydroxyapatite (HA) and HA-zirconium dioxide (HA/ZrO2) composite are materials with promising application in engineering of bone implants due to their excellent mechanical and structural properties. Biomorphic SiC ceramics have been synthesized from wood (Hornbeam, Sapele, Tilia and Pear) using a forced impregnation method. The SiC ceramics have been coated with bioactive HA and HA/ZrO2 using effective gas detonation deposition approach (GDD). The surface morphology and cytotoxicity of SiC ceramics as well as phase composition and crystallinity of deposited coatings were analyzed. It has been shown that the porosity and pore size of SiC ceramics depend on initial wood source. The XRD and FTIR studies revealed the preservation of crystal structure and phase composition of in the HA coating, while addition of ZrO2 to the initial HA powder resulted in significant decomposition of the final HA/ZrO2 coating and formation of other calcium phosphate phases. In turn, NIH 3T3 cells cultured in medium exposed to coated and uncoated SiC ceramics showed high re-cultivation efficiency as well as metabolic activity. The recultivation efficiency of cells was the highest for HA-coated ceramics, whereas HA/ZrO2 coating improved the recultivation efficiency of cells as compared to uncoated SiC ceramics. The GDD method allowed generating homogeneous HA coatings with no change in calcium to phosphorus ratio. In summary, porous and cytocompatible bio-SiC ceramics with bioactive coatings show a great promise in construction of light, robust, inexpensive and patient-specific bone implants for clinical application. PMID:27524006

  13. Bioactivity of thermal plasma synthesized bovine hydroxyapatite/glass ceramic composites

    NASA Astrophysics Data System (ADS)

    Yoganand, C. P.; Selvarajan, V.; Rouabhia, Mahmoud; Cannillo, Valeria; Sola, Antonella

    2010-02-01

    Bone injuries and failures often require the inception of implant biomaterials. Research in this area is receiving increasing attention worldwide. A variety of artificial bone materials, such as metals, polymeric materials, composites and ceramics, are being explored to replace diseased bones. Calcium phosphate ceramics are currently used as biomaterials for many applications in both dentistry and orthopedics. Bioactive silicate-based glasses show a higher bioactive behaviour than calcium phosphate materials. It is very interesting to study the mixtures of HA and silicate-based glasses. In the present study; natural bovine hydroxyapatite / SiO2-CaO-MgO glass composites were produced using the Transferred arc plasma (TAP) melting method. TAP melting route is a brisk process of preparation of glass-ceramics in which the raw materials are melted in the plasma and crystallization of the melt occurs while cooling down at a much faster rate in relatively short processing times compared to the conventional methods of manufacture of glass ceramics/composites. It is well known that; one essential step to the understanding of the biological events occurring at the bone tissue/material interface is the biological investigation by in vitro tests. Cell lines are commonly used for biocompatibility tests, and are very efficient because of their reproducibility and culture facility. In this study, we report the results of a study on the response of primary cultures of human fibroblast cells to TAP melted bioactive glass ceramics.

  14. Chemical and physicochemical characterization of porous hydroxyapatite ceramics made of natural bone.

    PubMed

    Joschek, S; Nies, B; Krotz, R; Göferich, A

    2000-08-01

    The properties of a porous hydroxyapatite ceramic produced by sintering of bovine bone were investigated by using a number of physicochemical methods such as scanning electron microscopy (SEM), SEM in combination with energy dispersive X-ray spectroscopy (SEM-EDX), mercury intrusion porosimetry, krypton-adsorption, contact angle measurements, wide angle X-ray diffraction. Fourier transform infrared spectroscopy, thermal analysis, inductively coupled plasma optical atom emissions spectroscopy and flame atomic absorption spectroscopy. The results indicate that there are considerable differences between the ceramic and native bone. However, the most important properties with respect to the use of such ceramics as a biomaterial for filling bone defects namely the high porosity (> or = 57 +/- 2%) and the interconnecting pore system are maintained. While macropores with an average diameter of approx. 300 microm contribute 97% to porosity, micropores with an average diameter of 1.3 microm account for only 3% of the total porosity. The surface area was found to be approx. 0.1 m2/g. The contact angles of water (44.6 +/- 15.4 degrees, n = 5) and tetrahydrofurane (10 degrees) allow the processing of the ceramic to a drug carrier by incubation with aqueous or organic drug solutions. The ceramic is highly crystalline with crystal sizes of 1-7 microm and contains crystal bridges. The investigation of its chemical composition revealed small amounts of other inorganic compounds such as Ca4O(PO4)2, NaCaPO4, Ca3(PO4)2, CaO, and MgO. Besides trace amounts of aluminum, iron, magnesium, potassium, silica, sodium, vanadium and zinc it contains probably carbonated apatite. PMID:10905406

  15. In vitro osteoclast formation and resorption of silicon-substituted hydroxyapatite ceramics.

    PubMed

    Friederichs, Robert J; Brooks, Roger A; Ueda, Masato; Best, Serena M

    2015-10-01

    Materials that participate in bone remodeling at the implant/tissue interface represent a modern tissue engineering approach with the aim of balancing implant resorption and nascent tissue formation. Silicon-substituted hydroxyapatite (SiHA) ceramics are capable of stimulating new bone formation, but little is known about their interaction with osteoclasts (OC). The effects of soluble silicate and SiHA on OCs were investigated in this study. Soluble silicate below 500 μM did not stimulate cell metabolism at 4 days or alter resorption area at 7 days on calcium phosphate discs. On sintered ceramics, OC numbers were similar on HA, Si0.3 HA (0.5 wt % Si) and Si0.5 HA (1.2 wt % Si) after 21 days in vitro, but actin ring sealing zone morphology on SiHA resembled that commonly found on bone or on carbonate-substituted hydroxyapatite (CHA). Smaller and thicker actin rings on SiHA as compared to HA were probably the result of altered surface chemistry and solubility differences. The more stable sealing zones and increased lattice solubility likely contributed to increased individual pit volumes observed on Si0.5 HA. The delayed formation of OCs on Si0.5 HA (lower numbers at day 14) excludes earlier differentiation as a possible mechanism of increased individual OC pit volumes at later times (day 21). Materials characterization of Si containing biomaterials remains paramount as the Si type and amounts can subsequently impact downstream OC behaviour in a complex manner. PMID:25847383

  16. Processing of an apatite-mullite glass-ceramic and an hydroxyapatite/phosphate glass composite by selective laser sintering.

    PubMed

    Lorrison, J C; Dalgarno, K W; Wood, D J

    2005-08-01

    The work presented details the results of an investigation into the feasibility of using Selective Laser Sintering (SLS) to directly produce customised bioceramic implants. The materials used were bioactive in nature and included a glass-ceramic and a combination of hydroxyapatite and phosphate glass. The glass-ceramic was selected from the range of apatite-mullite materials in the SiO2.Al2O3.CaO.CaF2.P2O5 series, due to their potentially suitable biological and mechanical properties. The hydroxyapatite and phosphate glass combination was chosen to allow an alternative production approach to be investigated. The viability of using both these materials with the SLS process was assessed and the process route and resulting material properties characterised using a variety of techniques including Differential Thermal Analysis (DTA), X-ray Diffraction (XRD) and Scanning Electron Microscopy (SEM). The results obtained indicate that it was possible to produce multiple layer components from both materials using the SLS process. The glass-ceramic materials could only be processed at very low scan speeds and powers, yielding relatively brittle components. It was though possible to produce parts from the hydroxyapatite and phosphate glass combination across a much wider range of parameters, producing parts which had a greater potential for possible implant production. PMID:15965749

  17. Effect of nano-hydroxyapatite coating on the osteoinductivity of porous biphasic calcium phosphate ceramics

    PubMed Central

    2014-01-01

    Background Porous biphasic calcium phosphate (BCP) ceramics exhibit good biocompatibility and bone conduction but are not inherently osteoinductive. To overcome this disadvantage, we coated conventional porous BCP ceramics with nano-hydroxyapatite (nHA). nHA was chosen as a coating material due to its high osteoinductive potential. Methods We used a hydrothermal deposition method to coat conventional porous BCP ceramics with nHA and assessed the effects of the coating on the physical and mechanical properties of the underlying BCP. Next, its effects on mesenchymal stem cell (MSC) attachment, proliferation, viability, and osteogenic differentiation were investigated. Results nHA formed a deposited layer on the BCP surface, and synthesized nHA had a rod-like shape with lengths ranging from ~50–200 nm and diameters from ~15–30 mm. The nHA coating did not significantly affect the density, porosity, flexural strength, or compressive strength of the underlying BCP (P > 0.1). Scanning electron microscopy showed MSC attachment to the scaffolds, with a healthy morphology and anchorage to nHA crystals via cytoplasmic processes. The densities of MSCs attached on BCP and nHA-coated BCP scaffolds were 62 ± 26 cells/mm2 and 63 ± 27 cells/mm2 (P > 0.1), respectively, after 1 day and 415 ± 62 cells/mm2 and 541 ± 35 cells/mm2 (P < 0.05) respectively, after 14 days. According to an MTT assay, MSC viability was higher on nHA-coated BCP scaffolds than on BCP scaffolds (P < 0.05). In addition, MSCs on nHA-coated BCP scaffolds produced more alkaline phosphatase, collagen type I, and osteocalcin than MSCs on BCP scaffolds (P < 0.05). Conclusions Our results demonstrate that BCP scaffolds coated with nHA were more conducive for MSC adhesion, proliferation, and osteogenic differentiation than conventional, uncoated BCP scaffolds, indicating that nHA coating can enhance the osteoinductive potential of BCP ceramics, making this material more

  18. Thermal and ultrasonic influence in the formation of nanometer scale hydroxyapatite bio-ceramic

    PubMed Central

    Poinern, GJE; Brundavanam, R; Le, X Thi; Djordjevic, S; Prokic, M; Fawcett, D

    2011-01-01

    Hydroxyapatite (HAP) is a widely used biocompatible ceramic in many biomedical applications and devices. Currently nanometer-scale forms of HAP are being intensely investigated due to their close similarity to the inorganic mineral component of the natural bone matrix. In this study nano-HAP was prepared via a wet precipitation method using Ca(NO3)2 and KH2PO4 as the main reactants and NH4OH as the precipitator under ultrasonic irradiation. The Ca/P ratio was set at 1.67 and the pH was maintained at 9 during the synthesis process. The influence of the thermal treatment was investigated by using two thermal treatment processes to produce ultrafine nano-HAP powders. In the first heat treatment, a conventional radiant tube furnace was used to produce nano-particles with an average size of approximately 30 nm in diameter, while the second thermal treatment used a microwave-based technique to produce particles with an average diameter of 36 nm. The crystalline structure and morphology of all nanoparticle powders produced were investigated using X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), transmission electron microscopy (TEM), and Fourier transform infrared spectroscopy (FT-IR). Both thermal techniques effectively produced ultrafine powders with similar crystalline structure, morphology and particle sizes. PMID:22114473

  19. Fine structure analysis of biocompatible ceramic materials based hydroxyapatite and metallic biomaterials 316L

    NASA Astrophysics Data System (ADS)

    Anghelina, F. V.; Ungureanu, D. N.; Bratu, V.; Popescu, I. N.; Rusanescu, C. O.

    2013-11-01

    The aim of this paper was to obtain and characterize (surface morphology and fine structure) two types of materials: Ca10(PO4)6(OH)2 hydroxyapatite powder (HAp) as biocompatible ceramic materials and AISI 316L austenitic stainless steels as metallic biomaterials, which are the components of the metal-ceramic composites used for medical implants in reconstructive surgery and prosthetic treatment. The HAp was synthesized by coprecipitation method, heat treated at 200 °C, 800 °C and 1200 °C for 4 h, analyzed by X-ray diffraction (XRD) and scanning electron microscope (SEM). The stainless steel 316L type was made by casting, annealing and machined with a low speed (100 mm/s) in order to obtain a smooth surface and after that has been studied from residual stresses point of view in three polishing regimes conditions: at low speed polishing (150 rpm), at high speed polishing (1500 rpm) and high speed-vibration contact polishing (1500 rpm) using wide angle X-ray diffractions (WAXD). The chemical compositions of AISI 316 steel samples were measured using a Foundry Master Spectrometer equipped with CCD detector for spectral lines and the sparking spots of AISI 316L samples were analyzed using SEM. By XRD the phases of HAp powders have been identified and also the degree of crystallinity and average size of crystallites, and with SEM, we studied the morphology of the HAp. It has been found from XRD analysis that we obtained HAp with a high degree of crystallinity at 800 °C and 1200 °C, no presence of impurity and from SEM analysis we noticed the influence of heat treatment on the ceramic particles morphology. From the study of residual stress profiles of 316L samples were observed that it differs substantially for different machining regimes and from the SEM analysis of sparking spots we revealed the rough surfaces of stainless steel rods necessary for a better adhesion of HAp on it.

  20. Mechanical and in vitro performance of apatite-wollastonite glass ceramic reinforced hydroxyapatite composite fabricated by 3D-printing.

    PubMed

    Suwanprateeb, J; Sanngam, R; Suvannapruk, W; Panyathanmaporn, T

    2009-06-01

    In situ hydroxyapatite/apatite-wollastonite glass ceramic composite was fabricated by a three dimensional printing (3DP) technique and characterized. It was found that the as-fabricated mean green strength of the composite was 1.27 MPa which was sufficient for general handling. After varying sintering temperatures (1050-1300 degrees C) and times (1-10 h), it was found that sintering at 1300 degrees C for 3 h gave the greatest flexural modulus and strength, 34.10 GPa and 76.82 MPa respectively. This was associated with a decrease in porosity and increase in densification ability of the composite resulting from liquid phase sintering. Bioactivity tested by soaking in simulated body fluid (SBF) and In Vitro toxicity studies showed that 3DP hydroxyapatite/A-W glass ceramic composite was non-toxic and bioactive. A new calcium phosphate layer was observed on the surface of the composite after soaking in SBF for only 1 day while osteoblast cells were able to attach and attain normal morphology on the surface of the composite. PMID:19225870

  1. Structural and Magnetic Characterizations of Nano Sized Grain Zinc Ferrite/Hydroxyapatite Ceramic Prepared by Solid State Reaction Route.

    PubMed

    Pankaew, Piyapong; Klumdoung, Pattarinee

    2015-11-01

    A promising composite of bioactive hydroxyapatite (HAp) and zinc ferrite (ZnFe2O4) has potentials for future bone reinforcing formation. In present study, HAp and ZnFe2O4 composite ceramic was prepared by solid state reaction route for easier control of structural and magnetic characteristics and with low cost. HAp powder was synthesized by precipitation method from chicken eggshell. Mixed powders with varying ZnFe2O4/HAp weight ratios from 2-10 wt% were milled together and uniaxially pressed and then sintered at 1200 degrees C for 3 hours. The XRD results showing no other phases of composite ceramics with only HAp and ZnFe2O4 phases were identified, indicating high stability of HAp property. Phase fractions of ZnFe2O4 were found to increase from 10.8 to 18.73 wt% with increasing content of ZnFe2O4. FT-IR results were only revealed vibration bands of standard HAp phase. SEM results revealed primary grains sizes of the prepared ceramics in nano scale. The BET surface area and pore volume increased with increasing content of ZnFe2O4 in composite ceramics. The VSM results of composites with increasing ZnFe2O4 content had been shown with increasing magnetization from 0.05 to 1.85 emu/g while their coercivities were decreased from 44 to 24 Oe. Higher magnetization as well as higher super paramagnetic behavior could be achieved with increasing the studied ZnFe2O4 weight ratios in ZnFe2O4/HAp composite ceramics, which can be tailored for specific applications. PMID:26726683

  2. Calcium silicate ceramic scaffolds toughened with hydroxyapatite whiskers for bone tissue engineering

    SciTech Connect

    Feng, Pei; Wei, Pingpin; Li, Pengjian; Gao, Chengde; Shuai, Cijun; Peng, Shuping

    2014-11-15

    Calcium silicate possessed excellent biocompatibility, bioactivity and degradability, while the high brittleness limited its application in load-bearing sites. Hydroxyapatite whiskers ranging from 0 to 30 wt.% were incorporated into the calcium silicate matrix to improve the strength and fracture resistance. Porous scaffolds were fabricated by selective laser sintering. The effects of hydroxyapatite whiskers on the mechanical properties and toughening mechanisms were investigated. The results showed that the scaffolds had a uniform and continuous inner network with the pore size ranging between 0.5 mm and 0.8 mm. The mechanical properties were enhanced with increasing hydroxyapatite whiskers, reached a maximum at 20 wt.% (compressive strength: 27.28 MPa, compressive Young's modulus: 156.2 MPa, flexural strength: 15.64 MPa and fracture toughness: 1.43 MPa·m{sup 1/2}) and then decreased by addition of more hydroxyapatite whiskers. The improvement of mechanical properties was due to whisker pull-out, crack deflection and crack bridging. Moreover, the degradation rate decreased with the increase of hydroxyapatite whisker content. A layer of bone-like apatite was formed on the scaffold surfaces after being soaked in simulated body fluid. Human osteoblast-like MG-63 cells spread well on the scaffolds and proliferated with increasing culture time. These findings suggested that the calcium silicate scaffolds reinforced with hydroxyapatite whiskers showed great potential for bone regeneration and tissue engineering applications. - Highlights: • HA whiskers were incorporated into CS to improve the properties. • The scaffolds were successfully fabricated by SLS. • Toughening mechanisms was whisker pull-out, crack deflection and bridging. • The scaffolds showed excellent apatite forming ability.

  3. Porous biphasic calcium phosphate ceramics coated with nano-hydroxyapatite and seeded with mesenchymal stem cells for reconstruction of radius segmental defects in rabbits.

    PubMed

    Hu, Jianzhong; Yang, Zhiming; Zhou, Yongchun; Liu, Yong; Li, Kaiyang; Lu, Hongbin

    2015-11-01

    The osteoconduction of porous biphasic calcium phosphate (BCP) ceramics has been widely reported. In a previous study, we demonstrated that applying a nano-hydroxyapatite (nHA) coating enhances the osteoinductive potential of BCP ceramics, making these scaffolds more suitable for bone tissue engineering applications. The aim of the present study was to determine the effects of reconstructing radius defects in rabbits using nHA-coated BCP ceramics seeded with mesenchymal stem cells (MSCs) and to compare the bone regeneration induced by different scaffolds. Radius defects were created in 20 New Zealand rabbits, which were divided into four groups by treatment: porous BCP ceramics (Group A), nHA-coated porous BCP ceramics (Group B), porous BCP ceramics seeded with rabbit MSCs (Group C), and nHA-coated porous BCP ceramics seeded with rabbit MSCs (Group D). After in vitro incubation, the cell/scaffold complexes were implanted into the defects. Twelve weeks after implantation, the specimens were examined macroscopically and histologically. Both the nHA coating and seeding with MSCs enhanced the formation of new bone tissue in the BCP ceramics, though the osteoinductive potential of the scaffolds with MSCs was greater than that of the nHA-coated scaffolds. Notably, the combination of nHA coating and MSCs significantly improved the bone regeneration capability of the BCP ceramics. Thus, MSCs seeded into porous BCP ceramics coated with nHA may be an effective bone substitute to reconstruct bone defects in the clinic. PMID:26449447

  4. Applicability assessment of ceramic microbeads coated with hydroxyapatite-binding silver/titanium dioxide ceramic composite earthplus™ to the eradication of Legionella in rainwater storage tanks for household use.

    PubMed

    Oana, Kozue; Kobayashi, Michiko; Yamaki, Dai; Sakurada, Tsukasa; Nagano, Noriyuki; Kawakami, Yoshiyuki

    2015-01-01

    Water environments appear to be the habitats of Legionella species. Legionellosis is considered as a preventable illness because bacterial reservoirs can be controlled and removed. Roof-harvested rainwater has attracted significant attention not only as a groundwater recharge but also as a potential alternative source of nonpotable water. We successfully developed ceramic microbeads coated with hydroxyapatite-binding silver/titanium dioxide ceramic composite earthplus™ using the thermal spraying method. The ceramic microbeads were demonstrated to have bactericidal activities against not only Legionella but also coliform and heterotrophic bacteria. Immersing the ceramic microbeads in household rainwater storage tanks was demonstrated to yield the favorable eradication of Legionella organisms. Not only rapid-acting but also long-lasting bactericidal activities of the ceramic microbead were exhibited against Legionella pneumophila. However, time-dependent attenuation of the bactericidal activities against Legionella were also noted in the sustainability appraisal experiment. Therefore, the problems to be overcome surely remain in constantly managing the Legionella-pollution by means of immersing the ceramic microbeads. The results of our investigation apparently indicate that the earthplus™-coated ceramic microbeads would become the favorable tool for Legionella measures in household rainwater storage tanks, which may become the natural reservoir for Legionella species. Our investigation would justify further research and data collection to obtain more reliable procedures to microbiologically regulate the Legionella in rainwater storage tanks. PMID:26346201

  5. Applicability assessment of ceramic microbeads coated with hydroxyapatite-binding silver/titanium dioxide ceramic composite earthplus™ to the eradication of Legionella in rainwater storage tanks for household use

    PubMed Central

    Oana, Kozue; Kobayashi, Michiko; Yamaki, Dai; Sakurada, Tsukasa; Nagano, Noriyuki; Kawakami, Yoshiyuki

    2015-01-01

    Water environments appear to be the habitats of Legionella species. Legionellosis is considered as a preventable illness because bacterial reservoirs can be controlled and removed. Roof-harvested rainwater has attracted significant attention not only as a groundwater recharge but also as a potential alternative source of nonpotable water. We successfully developed ceramic microbeads coated with hydroxyapatite-binding silver/titanium dioxide ceramic composite earthplus™ using the thermal spraying method. The ceramic microbeads were demonstrated to have bactericidal activities against not only Legionella but also coliform and heterotrophic bacteria. Immersing the ceramic microbeads in household rainwater storage tanks was demonstrated to yield the favorable eradication of Legionella organisms. Not only rapid-acting but also long-lasting bactericidal activities of the ceramic microbead were exhibited against Legionella pneumophila. However, time-dependent attenuation of the bactericidal activities against Legionella were also noted in the sustainability appraisal experiment. Therefore, the problems to be overcome surely remain in constantly managing the Legionella-pollution by means of immersing the ceramic microbeads. The results of our investigation apparently indicate that the earthplus™-coated ceramic microbeads would become the favorable tool for Legionella measures in household rainwater storage tanks, which may become the natural reservoir for Legionella species. Our investigation would justify further research and data collection to obtain more reliable procedures to microbiologically regulate the Legionella in rainwater storage tanks. PMID:26346201

  6. Characterization of ceramic hydroxyapatite surface by inverse liquid chromatography in aquatic systems.

    PubMed

    Kadlec, Karol; Adamska, Katarzyna; Voelkel, Adam

    2016-01-15

    The novel approach for hydroxyapatite (HA) surface characterization was proposed. The main aim of this investigation was to estimate surface properties of HA as a biomaterial in real system i.e. in simulated body fluid (SBF). One of the method, which might be used to reflect the influence of liquid environment on sorption properties of material being surrounded by this liquid, is called inverse liquid chromatography (ILC). The lowercase letters of LFER equation (e, s, a, b, v) served for this characterization. The sorption abilities of examined material were also estimated for two different aqueous mobile phases: deionized water and water solution of 0.1M Na2HPO4. It enabled to observe the change in physiochemical properties of surface, considered in Abraham model, dependence on ions concentration in the mobile phase. Moreover pH of every aquatic solution, normally about 7, was adjusted to 5.5 and 9 to observe the influence of hydrogen and hydroxyl ions concentration on HA sorption properties. PMID:26592574

  7. Structure-property relationships of iron-hydroxyapatite ceramic matrix nanocomposite fabricated using mechanosynthesis method.

    PubMed

    Nordin, Jamillah Amer; Prajitno, Djoko Hadi; Saidin, Syafiqah; Nur, Hadi; Hermawan, Hendra

    2015-06-01

    Hydroxyapatite (HAp) is an attractive bioceramics due to its similar composition to bone mineral and its ability to promote bone-implant interaction. However, its low strength has limited its application as load bearing implants. This paper presented a work focusing on the improvement of HAp mechanical property by synthesizing iron (Fe)-reinforced bovine HAp nanocomposite powders via mechanosynthesis method. The synthesis process was performed using high energy milling at varied milling time (3, 6, 9, and 12h). The samples were characterized by X-ray diffraction (XRD), Fourier transform infrared (FT-IR), and scanning electron microscopy (SEM). Its mechanical properties were investigated by micro-Vicker's hardness and compression tests. Results showed that milling time directly influenced the characteristics of the nanocomposite powders. Amorphous BHAp was formed after 9 and 12h milling in the presence of HPO4(2-) ions. Continuous milling has improved the crystallinity of Fe without changing the HAp lattice structure. The nanocomposite powders were found in spherical shape, agglomerated and dense after longer milling time. The hardness and Young's modulus of the nanocomposites were also increased at 69% and 66%, respectively, as the milling time was prolonged from 3 to 12h. Therefore, the improvement of the mechanical properties of nanocomposite was attributed to high Fe crystallinity and homogenous, dense structure produced by mechanosynthesis. PMID:25842138

  8. Combined effects of melatonin and FGF-2 on mouse preosteoblast behavior within interconnected porous hydroxyapatite ceramics - in vitro analysis.

    PubMed

    Rahman, Mohammad Zeshaan; Shigeishi, Hideo; Sasaki, Kazuki; Ota, Akira; Ohta, Kouji; Takechi, Masaaki

    2016-04-01

    Objective Biocompatible materials such as interconnected porous hydroxyapatite ceramics (IP-CHA) loaded with osteogenic cells and bioactive agents are part of an evolving concept for overcoming craniofacial defects by use of artificial bone tissue regeneration. Amongst the bioactive agents, melatonin (MEL) and basic fibroblast growth factor (FGF-2) have been independently reported to induce osteoblastic activity. The present in vitro study was undertaken to examine the relationship between these two bioactive agents and their combinatory effects on osteoblastic activity and mineralization in vitro. Material and Methods Mouse preosteoblast cells (MC3T3-E1) were seeded and cultured within cylindrical type of IP-CHA block (ø 4x7 mm) by vacuum-assisted method. The IP-CHA/MC3T3 composites were subjected to FGF-2 and/or MEL. The proliferation assay, alkaline phosphatase enzyme activity (ALP), mRNA expressions of late bone markers, namely Osteocalcin (OCN) and Osteopontin (OPN), and Alizarin Red staining were examined over a period of 7 days. Results FGF-2 mainly enhanced the proliferation of MC3T3-E1 cells within the IP-CHA constructs. MEL mainly induced the mRNA expression of late bone markers (OCN and OPN) and showed increased ALP activity of MC3T3 cells cultured within IP-CHA construct. Moreover, the combination of FGF-2 and MEL showed increased osteogenic activity within the IP-CHA construct in terms of cell proliferation, upregulated expressions of OCN and OPN, increased ALP activity and mineralization with Alizarin Red. The synergy of the proliferative potential of FGF-2 and the differentiation potential of MEL showed increased osteogenic activity in MC3T3-E1 cells cultured within IP-CHA constructs. Conclusion These findings indicate that the combination of FGF-2 and MEL may be utilized with biocompatible materials to attain augmented osteogenic activity and mineralization. PMID:27119764

  9. CaO--P2O5--Na2O-based sintering additives for hydroxyapatite (HAp) ceramics.

    PubMed

    Kalita, S J; Bose, S; Hosick, H L; Bandyopadhyay, A

    2004-05-01

    We have assessed the effect of CaO--P2O5--Na2O-based sintering additives on mechanical and biological properties of hydroxyapatite (HAp) ceramics. Five different compositions of sintering additives were selected and prepared by mixing of CaO, P2O5, and Na2CO3 powders. 2.5 wt% of each additive was combined with commercial HAp powder, separately, followed by ball milling, and sintering at 1250 degrees C and 1300 degrees C in a muffle furnace. Green and sintered densities of the compacts were analyzed for the influence of additives on densification of HAp. Phase analyses were carried out using an X-ray diffractometer. Vickers microhardness testing was used to evaluate hardness of sintered compacts of different compositions. A maximum microhardness of 4.6 (+/- 0.28) GPa was attained for a composition with 2.5 wt% addition of CaO:P2O5:Na2O in the ratio of 3:3:4. Results from mechanical property evaluation showed that some of these sintering additives improved failure strength of HAp under compressive loading. Maximum compressive strength was observed for samples with 2.5 wt% addition of CaO. Average failure strength for this set of samples was calculated to be 220 (+/- 50) MPa. Cytotoxicity, and cell attachment studies were carried out using a modified human osteoblast cell line called OPC-1. In vitro results showed that these compositions were non-toxic. Some sintering aids enhanced cell attachment and proliferation, which was revealed from SEM examination of the scaffolds seeded with OPC-1 cells. PMID:14741598

  10. Combined effects of melatonin and FGF-2 on mouse preosteoblast behavior within interconnected porous hydroxyapatite ceramics - in vitro analysis

    PubMed Central

    RAHMAN, Mohammad Zeshaan; SHIGEISHI, Hideo; SASAKI, Kazuki; OTA, Akira; OHTA, Kouji; TAKECHI, Masaaki

    2016-01-01

    ABSTRACT Objective Biocompatible materials such as interconnected porous hydroxyapatite ceramics (IP-CHA) loaded with osteogenic cells and bioactive agents are part of an evolving concept for overcoming craniofacial defects by use of artificial bone tissue regeneration. Amongst the bioactive agents, melatonin (MEL) and basic fibroblast growth factor (FGF-2) have been independently reported to induce osteoblastic activity. The present in vitro study was undertaken to examine the relationship between these two bioactive agents and their combinatory effects on osteoblastic activity and mineralization in vitro. Material and Methods Mouse preosteoblast cells (MC3T3-E1) were seeded and cultured within cylindrical type of IP-CHA block (ø 4x7 mm) by vacuum-assisted method. The IP-CHA/MC3T3 composites were subjected to FGF-2 and/or MEL. The proliferation assay, alkaline phosphatase enzyme activity (ALP), mRNA expressions of late bone markers, namely Osteocalcin (OCN) and Osteopontin (OPN), and Alizarin Red staining were examined over a period of 7 days. Results FGF-2 mainly enhanced the proliferation of MC3T3-E1 cells within the IP-CHA constructs. MEL mainly induced the mRNA expression of late bone markers (OCN and OPN) and showed increased ALP activity of MC3T3 cells cultured within IP-CHA construct. Moreover, the combination of FGF-2 and MEL showed increased osteogenic activity within the IP-CHA construct in terms of cell proliferation, upregulated expressions of OCN and OPN, increased ALP activity and mineralization with Alizarin Red. The synergy of the proliferative potential of FGF-2 and the differentiation potential of MEL showed increased osteogenic activity in MC3T3-E1 cells cultured within IP-CHA constructs. Conclusion These findings indicate that the combination of FGF-2 and MEL may be utilized with biocompatible materials to attain augmented osteogenic activity and mineralization. PMID:27119764

  11. Polymer-ceramic spiral structured scaffolds for bone tissue engineering: effect of hydroxyapatite composition on human fetal osteoblasts.

    PubMed

    Zhang, Xiaojun; Chang, Wei; Lee, Paul; Wang, Yuhao; Yang, Min; Li, Jun; Kumbar, Sangamesh G; Yu, Xiaojun

    2014-01-01

    For successful bone tissue engineering, a scaffold needs to be osteoconductive, porous, and biodegradable, thus able to support attachment and proliferation of bone cells and guide bone formation. Recently, hydroxyapatites (HA), a major inorganic component of natural bone, and biodegrade polymers have drawn much attention as bone scaffolds. The present study was designed to investigate whether the bone regenerative properties of nano-HA/polycaprolactone (PCL) spiral scaffolds are augmented in an HA dose dependent manner, thereby establishing a suitable composition as a bone formation material. Nano-HA/PCL spiral scaffolds were prepared with different weight ratios of HA and PCL, while porosity was introduced by a modified salt leaching technique. Human fetal osteoblasts (hFOBs) were cultured on the nano-HA/PCL spiral scaffolds up to 14 days. Cellular responses in terms of cell adhesion, viability, proliferation, differentiation, and the expression of bone-related genes were investigated. These scaffolds supported hFOBs adhesion, viability and proliferation. Cell proliferation trend was quite similar on polymer-ceramic and neat polymer spiral scaffolds on days 1, 7, and 14. However, the significantly increased amount of alkaline phosphatase (ALP) activity and mineralized matrix synthesis was evident on the nano-HA/PCL spiral scaffolds. The HA composition in the scaffolds showed a significant effect on ALP and mineralization. Bone phenotypic markers such as bone sialoprotein (BSP), osteonectin (ON), osteocalcin (OC), and type I collagen (Col-1) were semi-quantitatively estimated by reverse transcriptase polymerase chain reaction analysis. All of these results suggested the osteoconductive characteristics of HA/PCL nanocomposite and cell maturation were HA dose dependent. For instance, HA∶PCL = 1∶4 group showed significantly higher ALP mineralization and elevated levels of BSP, ON, OC and Col-I expression as compared other lower or higher ceramic ratios

  12. Polymer-Ceramic Spiral Structured Scaffolds for Bone Tissue Engineering: Effect of Hydroxyapatite Composition on Human Fetal Osteoblasts

    PubMed Central

    Zhang, Xiaojun; Chang, Wei; Lee, Paul; Wang, Yuhao; Yang, Min; Li, Jun; Kumbar, Sangamesh G.; Yu, Xiaojun

    2014-01-01

    For successful bone tissue engineering, a scaffold needs to be osteoconductive, porous, and biodegradable, thus able to support attachment and proliferation of bone cells and guide bone formation. Recently, hydroxyapatites (HA), a major inorganic component of natural bone, and biodegrade polymers have drawn much attention as bone scaffolds. The present study was designed to investigate whether the bone regenerative properties of nano-HA/polycaprolactone (PCL) spiral scaffolds are augmented in an HA dose dependent manner, thereby establishing a suitable composition as a bone formation material. Nano-HA/PCL spiral scaffolds were prepared with different weight ratios of HA and PCL, while porosity was introduced by a modified salt leaching technique. Human fetal osteoblasts (hFOBs) were cultured on the nano-HA/PCL spiral scaffolds up to 14 days. Cellular responses in terms of cell adhesion, viability, proliferation, differentiation, and the expression of bone-related genes were investigated. These scaffolds supported hFOBs adhesion, viability and proliferation. Cell proliferation trend was quite similar on polymer-ceramic and neat polymer spiral scaffolds on days 1, 7, and 14. However, the significantly increased amount of alkaline phosphatase (ALP) activity and mineralized matrix synthesis was evident on the nano-HA/PCL spiral scaffolds. The HA composition in the scaffolds showed a significant effect on ALP and mineralization. Bone phenotypic markers such as bone sialoprotein (BSP), osteonectin (ON), osteocalcin (OC), and type I collagen (Col-1) were semi-quantitatively estimated by reverse transcriptase polymerase chain reaction analysis. All of these results suggested the osteoconductive characteristics of HA/PCL nanocomposite and cell maturation were HA dose dependent. For instance, HA∶PCL = 1∶4 group showed significantly higher ALP mineralization and elevated levels of BSP, ON, OC and Col-I expression as compared other lower or higher ceramic ratios

  13. Calcium-ion-modulated ceramic hydroxyapatite resin for the scalable purification of recombinant Adeno-Associated Virus serotype 9.

    PubMed

    Qu, Weihong; Wang, Mingxi; Wu, Yaqing; Lv, Yinghui; Wang, Qizhao; Xu, Ruian

    2015-05-15

    Column chromatography has been widely used as a scalable purification strategy for recombinant adeno-associated virus (rAAV) vectors. The rAAV1, 2, 4, 5, 6, 8 and 9 serotypes could be separated using affinity resins, ion exchange resins or other types of resins. Apatite resin has displayed outstanding performance in protein purification in the past 10 years, and ceramic hydroxyapatite (CHT) chromatography resin with a polyethylene glycol (PEG) modulation has recently been used for rAAV1 and rAAV9 vectors. This study reports the use of CHT chromatography modulated by calcium ions instead of PEG for rAAV9 purification. Calcium-ion-containing buffers effectively improve the inclusion of CHT as a capture resin, the resin-binding capacity and the yield. The optimum calcium ion concentration is 30ppm, and the optimum pH is 7.0. A frontal analysis indicated that the binding capacity of CHT at 2ml/min reaches 65.1mg total protein per ml of resin. A previously developed purification strategy consists of CHT followed by ANX anion exchange chromatography. The vector yield of this approach is approximately 70%, and a software analysis indicated a vector purity exceeding 98%. The residual host cell (HEK293) protein contents are 24.75±2.32ng and 67.21±2.10ng, and the Benzonase residue contents are 1.55±0.10pg and 1.95±0.16ng per 10(13) vector genome copies (G.C.) separated by CHT/ANX and CsCl. In addition, CHT/ANX yields 798.44±50.10pg of plasmid DNA and 2.17±0.11ng of HEK293 DNA, while CsCl purification yields 840.27±76.14pg of plasmid DNA and 2.43±0.19 of HEK293 DNA. The two methods produce vectors with similar in vitro and in vivo potencies. The results indicated that the CHT/ANX method is suitable for the scalable purification of the rAAV9 vector. PMID:25841202

  14. "False" cytotoxicity of ions-adsorbing hydroxyapatite - Corrected method of cytotoxicity evaluation for ceramics of high specific surface area.

    PubMed

    Klimek, Katarzyna; Belcarz, Anna; Pazik, Robert; Sobierajska, Paulina; Han, Tomasz; Wiglusz, Rafal J; Ginalska, Grazyna

    2016-08-01

    An assessment of biomaterial cytotoxicity is a prerequisite for evaluation of its clinical potential. A material is considered toxic while the cell viability decreases under 70% of the control. However, extracts of certain materials are likely to reduce the cell viability due to the intense ions adsorption from culture medium (e.g. highly bioactive ceramics of high surface area). Thus, the standard ISO 10993-5 procedure is inappropriate for cytotoxicity evaluation of ceramics of high specific surface area because biomaterial extract obtained in this method (ions-depleted medium) is not optimal for cell cultures per se. Therefore, a simple test was designed as an alternative to ISO 10993-5 standard for cytotoxicity evaluation of the biomaterials of high surface area and high ions absorption capacity. The method, presented in this paper, included the evaluation of ceramics extract prepared according to corrected procedure. The corrected extract was found not cytotoxic (cell viability above 70%), suggesting that modified method for cytotoxicity evaluation of ions-adsorbing ceramics is more appropriate than ISO 10993-5 standard. For such biomaterials, the term "false" cytotoxicity is more suitable. Moreover, it was noted that NRU assay and microscopic observations should be recommended for cytotoxicity evaluation of ceramics of high surface area. PMID:27157729

  15. Electron microscopy of biomaterials based on hydroxyapatite

    SciTech Connect

    Suvorova, E. I. Klechkovskaya, V. V.; Komarov, V. F.; Severin, A. V.; Melikhov, I. V.; Buffat, P. A.

    2006-10-15

    Three types of biomaterials based on hydroxyapatite are synthesized and investigated. Hydroxyapatite nanocrystals or microcrystals precipitated from low-temperature aqueous solutions serve as the initial material used for preparing spherical porous granules approximately 300-500 {mu}m in diameter. Sintering of hydroxyapatite crystals at a temperature of 870 deg. C for 2 h or at 1000 deg. C (for 3 h) + 1200 deg. C (for 2 h) brings about the formation of solid ceramics with different internal structures. According to the electron microscopic data, the ceramic material prepared at 870 deg. C is formed by agglomerated hydroxyapatite nanocrystals, whereas the ceramics sintered at 1200 deg. C (with a bending strength of the order of 100 MPa) are composed of crystal blocks as large as 2 {mu}m. It is established that all the biomaterials have a single-phase composition and consist of the hydroxyapatite with a structure retained up to a temperature of 1200 deg. C.

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

    PubMed

    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. PMID:26354276

  17. Functionally Gradient Material Ceramics of Hydroxyapatite and Yttria Partially Stabilized Zirconia Prepared by Spark Plasma Sintering for Biocompatibility and Mechanical Strength

    NASA Astrophysics Data System (ADS)

    Kawagoe, Daisuke; Eda, Hokuto; Shinohara, Akiko; Nakata, Satoshi

    2013-01-01

    Hydroxyapatite, Ca10(PO4)6(OH)2: HA, is biocompatible with human hard tissue. Zirconia has mechanical strength and toughness. Spark plasma sintering (SPS) is a processing technique that makes it possible to prepare materials at low temperatures. Therefore, the objective of this study is to use the SPS method to prepare functionally gradient material (FGM) ceramics with the biocompatibility of HA and the strength of yttria partially stabilized zirconia (Y-PSZ). Fine powders of HA and Y-PSZ (ZrO2 + 3 mol % Y2O3) were poured into the graphite mold and then subjected to SPS at 1100 °C for 10 min. The outer layer has a mixing ratio of 70 wt % HA : 30 wt % Y-PSZ and the other layers are deposited by gradually changing the mixing ratio of HA and Y-PAZ. Each layer in the obtained composite (1.5 mmφ × 1.7 mm) was approximately 0.25 mm thick. The measured compressive strength of the composite prepared by SPS at 1100 °C for 10 min was 950 MPa.

  18. In vitro studies of composite bone filler based on poly(propylene fumarate) and biphasic α-tricalcium phosphate/hydroxyapatite ceramic powder.

    PubMed

    Wu, Chang-Chin; Yang, Kai-Chiang; Yang, Shu-Hua; Lin, Min-Huei; Kuo, Tzong-Fu; Lin, Feng-Huei

    2012-04-01

    While many different filler materials have been applied in vertebral augmentation procedures, none is perfect in all biomechanical and biological characteristics. To minimize possible shortages, we synthesized a new biodegradable, injectable, and premixed composite made from poly(propylene fumarate) (PPF) and biphasic α-tricalcium phosphate (α-TCP)/hydroxyapatite (HAP) ceramics powder and evaluated the material properties of the compound in vitro. We mixed the PPF cross-linked by N-vinyl pyrrolidinone and biphasic α-TCP/HAP powder in different ratios with benzoyl peroxide as an initiator. The setting time and temperature were recorded, although they could be manipulated by modulating the concentrations of hydroquinone and N,N-dimethyl-p-toluidine. Degradation, cytocompatibility, mechanical properties, and radiopacity were analyzed after the composites were cured by a cylindrical shape. We also compared the study materials with poly(methyl methacrylate) (PMMA) and PPF with pure HAP particles. Results showed that lower temperature during curing process (38-44°C), sufficient initial mechanical compressive fracture strength (61.1±3.7MPa), and gradual degradation were observed in the newly developed bone filler. Radiopacity in Hounsfield units was similar to PMMA as determined by computed tomography scan. Both pH value variation and cytotoxicity were within biological tolerable limits based on the biocompatibility tests. Mixtures with 70% α-TCP/HAP powder were superior to other groups. This study indicated that a composite of PPF and biphasic α-TCP/HAP powder is a promising, premixed, injectable biodegradable filler and that a mixture containing 70% α-TCP/HAP exhibits the best properties. PMID:22145803

  19. Electro-thermally polarized bulk and coated hydroxyapatite (HAp) ceramics---Understanding the role of surface charge, wettability and dopants on physical, mechanical and biological properties

    NASA Astrophysics Data System (ADS)

    Bodhak, Subhadip

    2010-11-01

    The objective of this study was to investigate the role of surface charge, wettability, and dopants on physical, mechanical and in vitro biological properties of bulk and coated electrothermally polarized hydroxyapatite (HAp) ceramics. For this purpose, bulk pure HAp compacts were prepared by sintering at 1200°C for 2h and HAp coating was fabricated on Ti substrate. Thermally stimulated depolarization current (TSDC) analysis revealed that a maximum surface charge of 4.05+/-0.33 microC/cm2 can be stored in bulk sintered HAp compacts while HAp coating samples exhibited a stored surface charge of 1.41+/-0.30 microC/cm2. It has been observed that increasing the surface potential led to decreasing of hydrophobicity of HAp surface without introducing any other volumetric effects in the material. In vitro bioactivity and bone cell-materials interaction results proved that increasing surface energy and wettability on negatively charged HAp surface significantly accelerated the apatite mineralization process by selectively adsorbing Ca2+ ions which promoted better hFOB cell attachment, proliferation and faster cells differentiation, especially at early time points, over unpoled HAp surface. In contrast, positively poled HAp surface exhibited inhibited hFOB cell proliferation and growth. Furthermore, dopants were incorporated into pure HAp in different single, binary and ternary composition to achieve combined benefits of matching bone chemistry and polarization effect. Small addition of Mg2+ and combined addition of Mg 2+-Sr2+ were found most optimal in enhancing density, mechanical properties as well as polarizability and charge storage ability of pure HAp. In vitro cell materials interaction study showed that presence of Mg2+ and Sr2+ can also significantly improved osteoblast activities on negatively charged surface. Finally, the interaction cell adhesive fibronectin protein on polarized doped and undoped HAp surfaces was investigated to get comprehensive understanding

  20. Tissue regeneration and repair of goat segmental femur defect with bioactive triphasic ceramic-coated hydroxyapatite scaffold.

    PubMed

    Nair, Manitha B; Varma, H K; Menon, K V; Shenoy, Sachin J; John, Annie

    2009-12-01

    Bone tissue engineering which is a developing and challenging field of science, is expected to enhance the regeneration and repair of bone lost from injury or disease and ultimately to gain its aesthetic contour. The objective of this study was to fabricate a tissue-engineered construct in vitro using a triphasic ceramic-coated hydroxypatite (HASi) in combination with stem cells and to investigate its potential in healing segmental defect in goat model. To accomplish this attempt, mesenchymal stem cells isolated from goat bone marrow were seeded onto HASi scaffolds and induced to differentiate into the osteogenic lineage in vitro. Scanning electron microscopy and light microscopy revealed adhesion and spread-out cells, which eventually formed a cell-sheet like canopy over the scaffold. Cells migrated and distributed themselves within the internal voids of the porous ceramic. Concurrently, the neo-osteogenesis of the tissue-engineered construct was validated in vivo in comparison with bare HASi (without cells) in goat femoral diaphyseal segmental defect (2 cm) at 4 months postimplantation through radiography, computed tomography, histology, histomorphometry, scanning electron microscopy and inductively coupled plasma spectrometry. Good osteointegration and osteoconduction was observed in bare and tissue-engineered HASi. The performance of tissue-engineered HASi was better and faster which was evident by the lamellar bone organization of newly formed bone throughout the defect together with the degradation of the material. On the contrary with bare HASi, immature woven bony bridges still intermingled with scattered small remnants of the material was observed in the mid region of the defect at 4 months. Encouraging results from this preclinical study has proved the capability of the tissue-engineered HASi as a promising candidate for the reconstruction of similar bony defects in humans. PMID:19065569

  1. Ceramics

    NASA Astrophysics Data System (ADS)

    Yao, Lichun; Yang, Jian; Qiu, Tai

    2014-09-01

    The effects of CuO addition on phase composition, microstructure, sintering behavior, and microwave dielectric properties of 0.80Sm(Mg0.5Ti0.5)O3-0.20 Ca0.8Sr0.2TiO3(8SMT-2CST) ceramics prepared by a conventional solid-state ceramic route have been studied. CuO addition shows no obvious influence on the phase of the 8SMT-2CST ceramics and all the samples exhibit pure perovskite structure. Appropriate CuO addition can effectively promote sintering and grain growth, and consequently improve the dielectric properties of the ceramics. The sintering temperature of the ceramics decreases by 50°C by adding 1.00 wt.%CuO. Superior microwave dielectric properties with a ɛ r of 29.8, Q × f of 85,500 GHz, and τ f of 2.4 ppm/°C are obtained for 1.00 wt.%CuO doped 8SMT-2CST ceramics sintered at 1500°C, which shows dense and uniform microstructure as well as well-developed grain growth.

  2. A histological study of non-ceramic hydroxyapatite as a bone graft substitute material in the vertical bone augmentation of the posterior mandible using an interpositional inlay technique: A split mouth evaluation.

    PubMed

    Bechara, Karen; Dottore, Alexandre M; Kawakami, Paulo Y; Gehrke, Sergio A; Coelho, Paulo G; Piattelli, Adriano; Iezzi, Giovanna; Shibli, Jamil Awad

    2015-11-01

    The aim of this study was to compare the influence of graft material (non-ceramic hydroxyapatite versus autologous bone) on bone behaviour and perform a resonance frequency analysis of implants placed in augmented sites to evaluate stability. For this study, 11 patients with bilateral edentulous areas in the mandibular posterior region were selected. Alveolar augmentation osteotomies were bilaterally (split mouth design) performed. In one hemiarch, the space generated by the osteotomy was grafted with an interpositional intra-oral autologous bone graft (control group). In the other hemiarch, the space generated by the osteotomy was grafted with an interpositional non-ceramic hydroxyapatite (ncHA) (test group). The groups were randomized. After 6 months of healing, a bone sample was retrieved from each side for histological evaluation using a trephine drill that was 2-mm in internal diameter. The implant stability quotient (ISQ) was measured by the resonance frequency immediately following implant placement at baseline and after 6 months of follow-up. Good incorporation of the graft was observed in both groups; however, in the test group, a residual-grafted material was observed. Bone density and marrow spaces were similar between groups. Correlations between the ISQ values and the histometric variables were not observed (p>0.05). The results of this trial suggest that both intra-oral autologous bone and ncHA may be elected as interpositional grafting materials to vertically augment posterior atrophic mandibles. PMID:26325427

  3. Ceramics

    NASA Astrophysics Data System (ADS)

    Chen, Song; Zhu, De-Gui; Cai, Xu-Sheng

    2014-08-01

    The dense monoclinic-SrAl2Si2O8 ceramics have been prepared by a two-step sintering process at a sintering temperature of 1173 K (900 °C). Firstly, the pre-sintered monoclinic-SrAl2Si2O8 powders containing small SiO2·Al2O3 crystal phases were obtained by continuously sintering a powder mixture of SrCO3 and kaolin at 1223 K (950 °C) for 6 hours and 1673 K (1400 °C) for 4 hours, respectively. Subsequently, by the combination of the pre-sintered ceramic powders with the composite flux agents, which are composed of a SrO·3B2O3 flux agent and α-Al2O3, the low-temperature densification sintering of the monoclinic-SrAl2Si2O8 ceramics was accomplished at 1173 K (900 °C). The low-temperature sintering behavior and microstructure evolvement of the monoclinic-SrAl2Si2O8 ceramics have been investigated in terms of Al2O3 in addition to the composite flux agents. It shows that due to the low-meting characteristics, the SrO·3B2O3 flux agent can urge the dense microstructure formation of the monoclinic-SrAl2Si2O8 ceramics and the re-crystallization of the grains via a liquid-phase sintering. The introduction of α-Al2O3 to the SrO·3B2O3 flux agent can apparently lead to more dense microstructures for the monoclinic-SrAl2Si2O8 ceramics but also cause the re-precipitation of SiO2·Al2O3 compounds because of an excessive Al2O3 content in the SrO·3B2O3 flux agent.

  4. Cementless Hydroxyapatite Coated Hip Prostheses

    PubMed Central

    Herrera, Antonio; Mateo, Jesús; Gil-Albarova, Jorge; Lobo-Escolar, Antonio; Ibarz, Elena; Gabarre, Sergio; Más, Yolanda

    2015-01-01

    More than twenty years ago, hydroxyapatite (HA), calcium phosphate ceramics, was introduced as a coating for cementless hip prostheses. The choice of this ceramic is due to its composition being similar to organic apatite bone crystals. This ceramic is biocompatible, bioactive, and osteoconductive. These qualities facilitate the primary stability and osseointegration of implants. Our surgical experience includes the implantation of more than 4,000 cementless hydroxyapatite coated hip prostheses since 1990. The models implanted are coated with HA in the acetabulum and in the metaphyseal area of the stem. The results corresponding to survival and stability of implants were very satisfactory in the long-term. From our experience, HA-coated hip implants are a reliable alternative which can achieve long term survival, provided that certain requirements are met: good design selection, sound choice of bearing surfaces based on patient life expectancy, meticulous surgical technique, and indications based on adequate bone quality. PMID:25802848

  5. Ceramics

    NASA Astrophysics Data System (ADS)

    Bin, Tang; Feng, Si; Ying-xiang, Li; He-tuo, Chen; Xiao, Zhang; Shu-ren, Zhang

    2014-11-01

    The effects of Ta2O5/Y2O3 codoping on the microstructure and microwave dielectric properties of Ba(Co0.56Zn0.40)1/3Nb2/3O3- xA- xB (A = 0.045 wt.% Ta2O5; B = 0.113 wt.% Y2O3) ceramics ( x = 0, 1, 2, 4, 8, 16, 32) prepared according to the conventional solid-state reaction technique were investigated. The x-ray diffraction (XRD) results showed that the main crystal phase in the sintered ceramics was BaZn0.33Nb0.67O3-Ba3CoNb2O9. The additional surface phase of Ba8CoNb6O24 and trace amounts of Ba5Nb4O15 second phase were present when Ta2O5/Y2O3 was added to the ceramics. The 1:2 B-site cation ordering was affected by the substitution of Ta5+ and Y3+ in the crystal lattice, especially for x = 4. Scanning electron microscopy (SEM) images of the optimally doped ceramics sintered at 1340°C for 20 h showed a compact microstructure with crystal grains in dense contact. Though the dielectric constant increased with the x value, appropriate addition would result in a tremendous modification of the Q × f and τ f values. Excellent microwave dielectric properties ( ɛ r = 35.4, Q × f = 62,993 GHz, and τ f = 2.6 ppm/°C) were obtained for the ceramic with x = 0.4 sintered in air at 1340°C for 20 h.

  6. Ceramics

    NASA Astrophysics Data System (ADS)

    Li, Enzhu; Zou, Mengying; Duan, Shuxin; Xu, Ning; Yuan, Ying; Zhou, Xiaohua

    2014-11-01

    The effects of excess Li content on the phase structure and microwave dielectric properties, especially on the temperature coefficient, of LiNb0.6 Ti0.5O3 (LNT) ceramics were studied. The results show that small amounts of Li effectively enhanced the sintering process due to the compensation of high volatility of Li, leading to a densification and homogenous microstructure, and therefore enhanced the dielectric properties. However, too much Li leads to a secondary phase and cause abnormal grain growth. The LNT + 5 wt.% Li ceramic sintered at 1075°C in the air shows the best properties of ɛ r = 69.73, Q × f = 5543 GHz, and τ f = -4.4 ppm/°C.

  7. Characterization of porous hydroxyapatite.

    PubMed

    Hing, K A; Best, S M; Bonfield, W

    1999-03-01

    Hydroxyapatite has been considered for use in the repair of osseous defects for the last 20 years. Recent developments have led to interest in the potential of porous hydroxyapatite as a synthetic bone graft. However, despite considerable activity in this field, regarding assessment of the biological response to such materials, the basic materials characterization is often inadequate. This paper documents the characterization of the chemical composition, mechanical integrity, macro- and microstructure of a porous hydroxyapatite, Endobon (E. Merck GmbH), intended for the bone-graft market. Specimens possesed a range of apparent densities from 0.35 to 1.44 g cm(-3). Chemical analysis demonstrated that the natural apatite precursor of Endobon was not converted to pure hydroxyapatite, but retained many of the ionic substituents found in bone mineral, notably carbonate, sodium and magnesium ions. Investigation of the microstructure illustrated that the struts of the material were not fully dense, but had retained some traces of the network of osteocyte lacunae. Macrostructural analysis demonstrated the complex inter-relationship between the structural features of an open pore structure. Both pore size and connectivity were found to be inversely dependent on apparent density. Furthermore, measurement of pore aspect ratio and orientation demonstrated a relationship between apparent density and the degree of macrostructural anisotropy within the specimens, while, it was also noted that pore connectivity was sensitive to anisotropy. Compression testing demonstrated the effect of apparent density and macrostructural anisotropy on the mechanical properties. An increase in apparent density from 0.38 to 1.25 g cm(-3) resulted in increases in ultimate compressive stress and compressive modulus of 1 to 11 MPa and 0.2 to 3.1 GPa, respectively. Furthermore, anisotropic high density (> 0.9 g cm(-3)) specimens were found to possess lower compressive moduli than isotropic specimens

  8. Nano-hydroxyapatite-coated metal-ceramic composite of iron-tricalcium phosphate: Improving the surface wettability, adhesion and proliferation of mesenchymal stem cells in vitro.

    PubMed

    Surmeneva, Maria A; Kleinhans, Claudia; Vacun, Gabriele; Kluger, Petra Juliane; Schönhaar, Veronika; Müller, Michaela; Hein, Sebastian Boris; Wittmar, Alexandra; Ulbricht, Mathias; Prymak, Oleg; Oehr, Christian; Surmenev, Roman A

    2015-11-01

    Thin radio-frequency magnetron sputter deposited nano-hydroxyapatite (HA) films were prepared on the surface of a Fe-tricalcium phosphate (Fe-TCP) bioceramic composite, which was obtained using a conventional powder injection moulding technique. The obtained nano-hydroxyapatite coated Fe-TCP biocomposites (nano-HA-Fe-TCP) were studied with respect to their chemical and phase composition, surface morphology, water contact angle, surface free energy and hysteresis. The deposition process resulted in a homogeneous, single-phase HA coating. The ability of the surface to support adhesion and the proliferation of human mesenchymal stem cells (hMSCs) was studied using biological short-term tests in vitro. The surface of the uncoated Fe-TCP bioceramic composite showed an initial cell attachment after 24h of seeding, but adhesion, proliferation and growth did not persist during 14 days of culture. However, the HA-Fe-TCP surfaces allowed cell adhesion, and proliferation during 14 days. The deposition of the nano-HA films on the Fe-TCP surface resulted in higher surface energy, improved hydrophilicity and biocompatibility compared with the surface of the uncoated Fe-TCP. Furthermore, it is suggested that an increase in the polar component of the surface energy was responsible for the enhanced cell adhesion and proliferation in the case of the nano-HA-Fe-TCP biocomposites. PMID:26277713

  9. Fabrication, Properties and Applications of Dense Hydroxyapatite: A Review

    PubMed Central

    Prakasam, Mythili; Locs, Janis; Salma-Ancane, Kristine; Loca, Dagnija; Largeteau, Alain; Berzina-Cimdina, Liga

    2015-01-01

    In the last five decades, there have been vast advances in the field of biomaterials, including ceramics, glasses, glass-ceramics and metal alloys. Dense and porous ceramics have been widely used for various biomedical applications. Current applications of bioceramics include bone grafts, spinal fusion, bone repairs, bone fillers, maxillofacial reconstruction, etc. Amongst the various calcium phosphate compositions, hydroxyapatite, which has a composition similar to human bone, has attracted wide interest. Much emphasis is given to tissue engineering, both in porous and dense ceramic forms. The current review focusses on the various applications of dense hydroxyapatite and other dense biomaterials on the aspects of transparency and the mechanical and electrical behavior. Prospective future applications, established along the aforesaid applications of hydroxyapatite, appear to be promising regarding bone bonding, advanced medical treatment methods, improvement of the mechanical strength of artificial bone grafts and better in vitro/in vivo methodologies to afford more particular outcomes. PMID:26703750

  10. Fabrication, Properties and Applications of Dense Hydroxyapatite: A Review.

    PubMed

    Prakasam, Mythili; Locs, Janis; Salma-Ancane, Kristine; Loca, Dagnija; Largeteau, Alain; Berzina-Cimdina, Liga

    2015-01-01

    In the last five decades, there have been vast advances in the field of biomaterials, including ceramics, glasses, glass-ceramics and metal alloys. Dense and porous ceramics have been widely used for various biomedical applications. Current applications of bioceramics include bone grafts, spinal fusion, bone repairs, bone fillers, maxillofacial reconstruction, etc. Amongst the various calcium phosphate compositions, hydroxyapatite, which has a composition similar to human bone, has attracted wide interest. Much emphasis is given to tissue engineering, both in porous and dense ceramic forms. The current review focusses on the various applications of dense hydroxyapatite and other dense biomaterials on the aspects of transparency and the mechanical and electrical behavior. Prospective future applications, established along the aforesaid applications of hydroxyapatite, appear to be promising regarding bone bonding, advanced medical treatment methods, improvement of the mechanical strength of artificial bone grafts and better in vitro/in vivo methodologies to afford more particular outcomes. PMID:26703750

  11. Aesthetic recovery of alveolar atrophy following autogenous onlay bone grafting using interconnected porous hydroxyapatite ceramics (IP-CHA) and resorbable poly-L-lactic/polyglycolic acid screws: case report

    PubMed Central

    2014-01-01

    Background Onlay bone grafting techniques have some problems related to the limited volume of autogenous grafted bone and need for surgery to remove bone fixing screws. Here, we report a case of horizontal alveolar ridge atrophy following resection of a maxillary bone cyst, in which autogenous onlay bone grafting with interconnected porous hydroxyapatite ceramics (IP-CHA) and bioresorbable poly-L-lactic/polyglycolic acid (PLLA-PGA) screws was utilized. Case presentation A 51-year-old man had aesthetic complications related to alveolar atrophy following maxillary bone cyst extraction. We performed onlay grafting for aesthetic alveolar bone recovery using IP-CHA to provide adequate horizontal bone volume and PLLA-PGA screws for bone fixing to avoid later damage to host bone during surgical removal. During the operation, an autogenous cortical bone block was collected from the ramus mandibular and fixed to the alveolar ridge with PLLA-PGA screws, then the gap between the bone block and recipient bone was filled with a granular type of IP-CHA. Post-surgery orthopantomograph and CT scan findings showed no abnormal resorption of the grafted bone, and increased radiopacity, which indicated new bone formation in the area implanted with IP-CHA. Conclusion Our results show that IP-CHA and resorbable PLLA-PGA screws are useful materials for autogenous onlay bone grafting. PMID:24889647

  12. Si-substituted hydroxyapatite nanopowders: Synthesis, thermal stability and sinterability

    SciTech Connect

    Bianco, Alessandra Cacciotti, Ilaria; Lombardi, Mariangela Montanaro, Laura

    2009-02-04

    Synthetic hydroxyapatites incorporating small amounts of Si have shown improved biological performances in terms of enhanced bone apposition, bone in-growth and cell-mediated degradation. This paper reports a systematic investigation on Si-substituted hydroxyapatite (Si 1.40 wt%) nanopowders produced following two different conventional wet methodologies: (a) precipitation of Ca(NO{sub 3}){sub 2}.4H{sub 2}O and (b) titration of Ca(OH){sub 2}. The influence of the synthesis process on composition, thermal behaviour and sinterability of the resulting nanopowders is studied. Samples were characterised by electron microscopy, induced coupled plasma atomic emission spectroscopy, thermal analysis, infrared spectroscopy, N{sub 2} adsorption measurements, X-ray diffraction and dilatometry. Semicrystalline Si-substituted hydroxyapatite powders made up of needle-like nanoparticles were obtained, the specific surface area ranged between 84 and 110 m{sup 2}/g. Pure and Si-substituted hydroxyapatite nanopowders derived from Ca(NO{sub 3}){sub 2}.4H{sub 2}O decomposed around 1000 deg. C. Si-substituted hydroxyapatite nanopowders obtained from Ca(OH){sub 2} were thermally stable up to 1200 deg. C and showed a distinct decreased thermal stability with respect to the homologous pure sample. Si-substituted hydroxyapatites exhibited higher sintering temperature and increased total shrinkage with respect to pure powders. Nanostructured dense ceramics were obtained by sintering at 1100 deg. C Si-substituted hydroxyapatites derived from Ca(OH){sub 2}.

  13. Substituted Hydroxyapatites with Antibacterial Properties

    PubMed Central

    Kolmas, Joanna; Groszyk, Ewa; Kwiatkowska-Różycka, Dagmara

    2014-01-01

    Reconstructive surgery is presently struggling with the problem of infections located within implantation biomaterials. Of course, the best antibacterial protection is antibiotic therapy. However, oral antibiotic therapy is sometimes ineffective, while administering an antibiotic at the location of infection is often associated with an unfavourable ratio of dosage efficiency and toxic effect. Thus, the present study aims to find a new factor which may improve antibacterial activity while also presenting low toxicity to the human cells. Such factors are usually implemented along with the implant itself and may be an integral part of it. Many recent studies have focused on inorganic factors, such as metal nanoparticles, salts, and metal oxides. The advantages of inorganic factors include the ease with which they can be combined with ceramic and polymeric biomaterials. The following review focuses on hydroxyapatites substituted with ions with antibacterial properties. It considers materials that have already been applied in regenerative medicine (e.g., hydroxyapatites with silver ions) and those that are only at the preliminary stage of research and which could potentially be used in implantology or dentistry. We present methods for the synthesis of modified apatites and the antibacterial mechanisms of various ions as well as their antibacterial efficiency. PMID:24949423

  14. Recent advances in ceramics for dentistry.

    PubMed

    Deany, I L

    1996-01-01

    For the last ten years, the application of high-technology processes to dental ceramics allowed for the development of new materials such as heat-pressed, injection-molded, and slip-cast ceramics and glass-ceramics. The purpose of the present paper is to review advances in new materials and processes available for making all-ceramic dental restorations. Concepts on the structure and strengthening mechanisms of dental ceramics are provided. Major developments in materials for all-ceramic restorations are addressed. These advances include improved processing techniques and greater mechanical properties. An overview of the processing techniques available for all-ceramic materials is given, including sintering, casting, machining, slip-casting, and heat-pressing. The most recent ceramic materials are reviewed with respect to their principal crystalline phases, including leucite, alumina, forsterite, zirconia, mica, hydroxyapatite, lithium disilicate, sanidine, and spinel. Finally, a summary of flexural strength data available for all-ceramic materials is included. PMID:8875028

  15. Dissolution of human teeth-derived hydroxyapatite.

    PubMed

    Seo, Dong Seok; Lee, Jong Kook

    2008-01-01

    We have been interested in human teeth which consist of hydroxyapatite (HA), but do not degrade for a long time. In order to overcome dissolution and mechanical degradation of man-made HA, biologically derived hydroxyapatite (BHA) ceramics were prepared from human teeth and their dissolving behavior was investigated in distilled water for 3-14 days and compared with an artificial HA made of synthetic HA powder. BHA ceramics were prepared by calcining freshly extracted human teeth at 900 degrees C and followed by sintering at 1200 degrees C for 2 h. All detectable peaks in the artificial HA are identical to HA lattice planes, whereas BHA consisted of a mixture of HA and beta-tricalcium phosphate (TCP). Although the artificial HA was expected to be stable in water, the surface dissolution initiated at grain boundaries followed by generated many separated grains and their associated pores. On the other hand, BHA showed that definite grains considered as beta-TCP were predominantly dissolved and the grains were separated from the matrix leaving pores. In the mean time, the rest region, mainly consisting of HA, did not show any evidence of dissolution. It indicates that BHA showed rather stable grain boundaries and lack of excessive dissolution in liquid environment. PMID:17943445

  16. Nanostructured nickel-free austenitic stainless steel/hydroxyapatite composites.

    PubMed

    Tulinski, Maciej; Jurczyk, Mieczyslaw

    2012-11-01

    In this work Ni-free austenitic stainless steels with nanostructure and their nanocomposites with hydroxyapatite are presented and characterized by means of X-ray diffraction and optical profiling. The samples were synthesized by mechanical alloying, heat treatment and nitriding of elemental microcrystalline powders with addition of hydroxyapatite (HA). In our work we wanted to introduce into stainless steel hydroxyapatite ceramics that have been intensively studied for bone repair and replacement applications. Such applications were chosen because of their high biocompatibility and ability to bond to bone. Since nickel-free austenitic stainless steels seem to have better mechanical properties, corrosion resistance and biocompatibility compared to 316L stainless steels, it is possible that composite made of this steel and HA could improve properties, as well. Mechanical alloying and nitriding are very effective technologies to improve the corrosion resistance of stainless steel. Similar process in case of nanocomposites of stainless steel with hydroxyapatite helps achieve even better mechanical properties and corrosion resistance. Hence nanocrystalline nickel-free stainless steels and nickel-free stainless steel/hydroxyapatite nanocomposites could be promising bionanomaterials for use as a hard tissue replacement implants, e.g., orthopedic implants. In such application, the surface roughness and more specifically the surface topography influences the proliferation of cells (e.g., osteoblasts). PMID:23421285

  17. A process for the development of strontium hydroxyapatite

    NASA Astrophysics Data System (ADS)

    Zahra, N.; Fayyaz, M.; Iqbal, W.; Irfan, M.; Alam, S.

    2014-06-01

    A procedure for the preparation of Strontium Hydroxyapatite is adapted to produce high purity and better homogeneity ceramic with good Crystallinity. The strontium substituted bone cement has potential for use in orthopedic surgeries. Ionic Strontium (Sr) in humans shares the same physiological pathway as calcium and can be deposited in the mineral structure of the bone. In the present study, a novel concept of preparing Sr-contained Hydroxyapatite bone cement by using a precipitation method is proposed to get an ideal biomaterial that possesses potential degradability and more excellent pharmacological effect. Chemical analysis, Fourier Transform Infra Red analysis and Thermogravimetric/ Differential Scanning Calorimetric studies were conducted on prepared Strontium Hydroxyapatite sample to characterize the incorporation of 15% Sr2+ into the crystal lattice of Hydroxyapatite. Strontium was quantitatively incorporated into Hydroxyapatite where its substitution for calcium provoked a linear shift of the infrared absorption bands of the hydroxyl and phosphate groups. Thus, the formation of Sr-HAp was confirmed by Chemical Analysis, FT-IR and TGA/DSC results.

  18. Hydroxyapatite with environmental applications

    SciTech Connect

    Popa, C. L.; Ciobanu, C. S.; Predoi, D.; Petre, C. C.; Jiga, G.; Motelica-Heino, M.; Iconaru, S. L.

    2014-05-15

    The aim of this study was to synthetize new nanoparticles based on methyltrimethoxysilane coated hydroxyapatite (MTHAp) for lead removal in aqueous solutions. The morphological and compositional analysis of MTHAp was investigated by scanning electron microscopy (SEM) equipped with an energy dispersive X-ray spectrometer (EDS). Removal experiments of Pb{sup 2+} ions were carried out in aqueous solutions with controlled concentration of Pb{sup 2+} and at fixed pH of 5. After the removal experiment of Pb{sup 2+} ions from solutions, porous hydroxyapatite nanoparticles were transformed into PbMTHAp-5 via the adsorption of Pb{sup 2+} ions followed by a cation exchange reaction. Our results demonstrate that the porous hydroxyapatite nanoparticles can be used as an adsorbent for removing Pb{sup 2+} ions from aqueous solution.

  19. Monoclonal antibody purification with hydroxyapatite.

    PubMed

    Gagnon, Pete

    2009-06-01

    Hydroxyapatite (HA) has been used for IgG purification since its introduction in the 1950s. Applications expanded to include IgA and IgM in the 1980s, along with elucidation of its primary binding mechanisms and the development of ceramic HA media. With the advent of recombinant monoclonal antibodies, HA was demonstrated to be effective for removal of antibody aggregates, as well as host cell proteins and leached protein A. HA's inherent abilities have been enhanced by the development of elution strategies that permit differential control of its primary binding mechanisms: calcium metal affinity and phosphoryl cation exchange. These strategies support reduction of antibody aggregate content from greater than 60% to less than 0.1%, in conjunction with enhanced removal of DNA, endotoxin, and virus. HA also has a history of discriminating various immunological constructs on the basis of differences in their variable regions, or discriminating Fab fragments from Fc contaminants in papain digests of purified monoclonal IgG. Continuing development of novel elution strategies, alternative forms of HA, and application of robotic high throughput screening systems promise to expand HA's utility in the field. PMID:19491046

  20. Preparation and characterization of hydroxyapatite/sodium alginate biocomposites for bone implant application

    NASA Astrophysics Data System (ADS)

    Kanasan, Nanthini; Adzila, Sharifah; Suid, Mohd Syafiq; Gurubaran, P.

    2016-07-01

    In biomedical fields, synthetic scaffolds are being improved by using the ceramics, polymers and composites materials to avoid the limitations of allograft. Ceramic-polymer composites are appearing to be the most successful bone graft substitute in human body. The natural bones itself are well-known as composite of collagen and hydroxyapatite. In this research, precipitation method was used to synthesis hydroxyapatite (HA)/sodium alginate (SA) in various parameters. This paper describes the hydroxyapatite/sodium alginate biocomposite which suitable for use in bone defects or regeneration of bone through the characterizations which include FTIR, FESEM, EDS and DTA. In FTIR, the characteristi peaks of PO4-3 and OH- groups which corresponding to hydroxyapatite are existed in the mixing powders. The needle-size particle of hydroxyapatite/ alginate (HA/SA) are observed in FESEM in the range of 15.8nm-38.2nm.EDS confirmed the existence of HA/SA composition in the mixing powders. There is an endothermic peak which corresponds to the dehydration and the loss of physically adsorbed water molecules of the hydroxyapatite (HA)/sodium alginate (SA) powder which are described in DTA.

  1. Synthesis and properties of hybrid hydroxyapatite-ferrite (Fe3O4) particles for hyperthermia applications

    NASA Astrophysics Data System (ADS)

    Tkachenko, M. V.; Kamzin, A. S.

    2016-04-01

    Hybrid ceramics consisting of hydroxyapatite Ca10(PO4)6(OH)2 and ferrite Fe3O4 were synthesized using a two-stage procedure. The first stage included the synthesis of Fe3O4 ferrite particles by co-precipitation and the synthesis of hydroxyapatite. In the second stage, the magnetic hybrid hydroxyapatite-ferrite bioceramics were synthesized by a thorough mixing of the obtained powders of carbonated hydroxyapatite and Fe3O4 ferrite taken in a certain proportion, pressing into tablets, and annealing in a carbon dioxide atmosphere for 30 min at a temperature of 1200°C. The properties of the components and hybrid particles were investigated using X-ray diffraction, scanning electron microscopy, transmission electron microscopy, and Mössbauer spectroscopy. The saturation magnetization of the hybrid ceramic composite containing 20 wt % Fe3O4 was found to be 12 emu/g. The hybrid hydroxyapatite (Ca10(PO4)6(OH)2)-ferrite Fe3O4 ceramics, which are promising for the use in magnetotransport and hyperthermia treatment, were synthesized and investigated for the first time.

  2. Bio resorbability of the modified hydroxyapatite in Tris-HCL buffer

    NASA Astrophysics Data System (ADS)

    Golovanova, O. A.; Izmailov, R. R.; Ghyngazov, S. A.

    2016-02-01

    The solubility of carbonated hydroxyapatite powders and granulated carbonated hydroxyapatite produced from the synovial biofluid model solution has been studied. The kinetic characteristics of dissolution were determined. It was found that the solubility of carbonated hydroxyapatite is higher as compared to that of hydroxyapatite. The impact of the organic matrix on the rate of sample dissolution was revealed. For HA-gelatin composites, as the gelatin concentration grows, the dissolution rate becomes greater, and a sample of 6.0 g / L concentration has higher resorbability. The results of the research can be used to study the kinetics of dissolution and the biocompatibility of ceramic materials for medicine, namely for reconstructive surgery, dentistry, and development of drug delivery systems.

  3. Fractography of glasses and ceramics II

    SciTech Connect

    Frechette, V.D.; Varner, J.R.

    1991-01-01

    Topics addressed include finite element stress analysis and crack path prediction of imploding CRT; fractography and fracture mechanics of combustion growth diamond thin films; the fracture behavior of machineable hydroxyapatite; a fractal approach to crack branching (bifurcation) in glass; the fracture of glass-ionomer cements; the effect of quartz particle size on the strength and toughness of whitewares; and a proposed standard practice for fractographic analysis of monolithic advanced ceramics. Also treated are thermal exposure effects on ceramic matrix composites, fractography applied to rock core analysis, fractography of flexurally fractured glass rods, the fractographic determination of K(IC) and effects of microstructural effects in ceramics.

  4. Biological reactivity of zirconia-hydroxyapatite composites.

    PubMed

    Silva, Viviane V; Lameiras, Fernando S; Lobato, Zélia I P

    2002-01-01

    Materials and devices intended for end-use applications as implants and medical devices must be evaluated to determine their biocompatibility potential in contact with physiological systems. The use of standard practices of biological testing provides a reasonable level of confidence concerning the response of a living organism to a given material or device, as well as guidance in selecting the proper procedures to be carried out for the screening of new or modified materials. This article presents results from cytotoxicity assays of cell culture, skin irritation, and acute toxicity by systemic and intracutaneous injections for powders, ceramic bodies, and extract liquids of hydroxyapatite (HA), calcia partially stabilized zirconia (ZO), and two types of zirconia-hydroxyapatite composites (Z4H6 and Z6H4) with potential for future use as orthopedic and dental implants. They indicate that these materials present potential for this type of application because they meet the requirements of the standard practices recommended for evaluating the biological reactivity of ATCC cell cultures (CCL1 NCTC clone 929 of mouse connective tissue and CCL 81 of monkey connective tissue) and animals (rabbit and mouse) with direct or indirect patient contact, or by the injection of specific extracts prepared from the material under test. In addition, studies involving short-term intramuscular and long-term implantation assays to estimate the reaction of living tissue to the composites studied, and investigations on long-term effects that these materials can cause on the cellular metabolism, are already in progress. PMID:12209904

  5. Portfolio: Ceramics.

    ERIC Educational Resources Information Center

    Hardy, Jane; And Others

    1982-01-01

    Describes eight art activities using ceramics. Elementary students created ceramic tiles to depict ancient Egyptian and medieval European art, made ceramic cookie stamps, traced bisque plates on sketch paper, constructed clay room-tableaus, and designed clay relief masks. Secondary students pit-fired ceramic pots and designed ceramic Victorian…

  6. Scratch and wear behaviour of plasma sprayed nano ceramics bilayer Al2O3-13 wt%TiO2/hydroxyapatite coated on medical grade titanium substrates in SBF environment

    NASA Astrophysics Data System (ADS)

    Palanivelu, R.; Ruban Kumar, A.

    2014-10-01

    Among the various coating techniques, plasma spray coating is an efficient technique to protect the metal surface from the various surface problems like wear and corrosion. The aim of this present work is to design and produce a bilayer coating on the non- toxic commercially pure titanium (denoted as CP-Ti) implant substrate in order to improve the biocompatibility and surface properties. To achieve that, Al2O3-13 wt%TiO2 (AT13) and hydroxyapatite (HAP) were coated on CP-Ti implant substrate using plasma spray coating technique. Further, the coated substrates were subjected to various characterization techniques. The crystallite size of coated HAP and its morphological studies were carried out using X-ray diffractometer (XRD) and scanning electron microscopy (SEM) respectively. The wear test on the bilayer (AT13/HAP) coated CP-Ti implant surface was conducted using ball-on-disc tester under SBF environment at 37 °C, in order to determine the wear rate and the coefficient of friction. The adhesion strength of the bilayer coated surface was evaluated by micro scratch tester under the ramp load conditions with load range of 14-20 N. The above said studies were repeated on the single layer coated HAP and AT13 implant surfaces. The results reveal that the bilayer (AT13/HAP) coated CP-Ti surface has the improved wear rate, coefficient of friction in compared to single layer coated HAP and AT13 surfaces.

  7. Characterisations of collagen-silver-hydroxyapatite nanocomposites

    NASA Astrophysics Data System (ADS)

    Ciobanu, C. S.; Popa, C. L.; Petre, C. C.; Jiga, G.; Trusca, R.; Predoi, D.

    2016-05-01

    The XRD analysis were performed to confirm the formation of hydroxyapatite structure in collagen-silver-hydroxyapatite nanocomposites. The molecular interaction in collagen-hydroxyapatite nanocomposites was highlighted by Fourier transform infrared spectroscopy (FTIR) analysis. The SEM showed a nanostructure of collagen-silverhydroxyapatite nanocomposites composed of nano needle-like particles in a veil with collagen texture. The presence of vibrational groups characteristics to the hydroxyapatite structure in collagen-silver-hydroxyapatite (AgHApColl) nanocomposites was investigated by FTIR.

  8. Accurate Fabrication of Hydroxyapatite Bone Models with Porous Scaffold Structures by Using Stereolithography

    NASA Astrophysics Data System (ADS)

    Maeda, Chiaki; Tasaki, Satoko; Kirihara, Soshu

    2011-05-01

    Computer graphic models of bioscaffolds with four-coordinate lattice structures of solid rods in artificial bones were designed by using a computer aided design. The scaffold models composed of acryl resin with hydroxyapatite particles at 45vol. % were fabricated by using stereolithography of a computer aided manufacturing. After dewaxing and sintering heat treatment processes, the ceramics scaffold models with four-coordinate lattices and fine hydroxyapatite microstructures were obtained successfully. By using a computer aided analysis, it was found that bio-fluids could flow extensively inside the sintered scaffolds. This result shows that the lattice structures will realize appropriate bio-fluid circulations and promote regenerations of new bones.

  9. Hydroxyapatite for Keratoprosthesis Biointegration

    PubMed Central

    Wang, Liqiang; Jeong, Kyung Jae; Chiang, Homer H.; Zurakowski, David; Behlau, Irmgard; Chodosh, James; Dohlman, Claes H.; Langer, Robert

    2011-01-01

    Purpose. Integration of keratoprosthesis with the surrounding cornea is very important in preventing bacterial invasion, which may cause ocular injury. Here the authors investigated whether hydroxyapatite (HAp) coating can improve keratoprosthesis (KPro) biointegration, using polymethyl methacrylate (PMMA)—the principal component of the Boston KPro—as a model polymer. Methods. HAp coatings were induced on PMMA discs after treatment with concentrated NaOH and coating with poly-dopamine (PDA) or polydopamine and then with 11-mercaptoundecanoic acid (11-MUA). Coatings were characterized chemically (Fourier transform infrared spectroscopy [FTIR], energy dispersive X-ray spectroscopy [EDX]) and morphologically (SEM) and were used as substrates for keratocyte growth in vitro. Cylinders of coated PMMA were implanted in porcine corneas ex vivo for 2 weeks, and the force required to pull them out was measured. The inflammatory reaction to coated discs was assessed in the rabbit cornea in vivo. Results. FTIR of the coatings showed absorption bands characteristic of phosphate groups, and EDX showed that the Ca/P ratios were close to those of HAp. By SEM, each method resulted in morphologically distinct HAp films; the 11-MUA group had the most uniform coating. The hydroxyapatite coatings caused comparable enhancement of keratocyte proliferation compared with unmodified PMMA surfaces. HAp coating significantly increased the force and work required to pull PMMA cylinders out of porcine corneas ex vivo. HAp coating of implants reduced the inflammatory response around the PMMA implants in vivo. Conclusions. These results are encouraging for the potential of HAp-coated surfaces for use in keratoprostheses. PMID:21849419

  10. Deposition of titanium nitride and hydroxyapatite-based biocompatible composite by reactive plasma spraying

    NASA Astrophysics Data System (ADS)

    Roşu, Radu Alexandru; Şerban, Viorel-Aurel; Bucur, Alexandra Ioana; Dragoş, Uţu

    2012-02-01

    Titanium nitride is a bioceramic material successfully used for covering medical implants due to the high hardness meaning good wear resistance. Hydroxyapatite is a bioactive ceramic that contributes to the restoration of bone tissue, which together with titanium nitride may contribute to obtaining a superior composite in terms of mechanical and bone tissue interaction matters. The paper presents the experimental results in obtaining composite layers of titanium nitride and hydroxyapatite by reactive plasma spraying in ambient atmosphere. X-ray diffraction analysis shows that in both cases of powders mixtures used (10% HA + 90% Ti; 25% HA + 75% Ti), hydroxyapatite decomposition occurred; in variant 1 the decomposition is higher compared with the second variant. Microstructure of the deposited layers was investigated using scanning electron microscope, the surfaces presenting a lamellar morphology without defects such as cracks or microcracks. Surface roughness values obtained vary as function of the spraying distance, presenting higher values at lower thermal spraying distances.

  11. Recent advances in synthesis, characterization of hydroxyapatite/polyurethane composites and study of their biocompatible properties.

    PubMed

    Popescu, L M; Piticescu, R M; Antonelli, A; Rusti, C F; Carboni, E; Sfara, C; Magnani, M; Badilita, V; Vasile, E; Trusca, R; Buruiana, T

    2013-11-01

    The development of engineered biomaterials that mimic bone tissues is a promising research area that benefits from a growing interest. Polymers and polymer-ceramic composites are the principle materials investigated for the development of synthetic bone scaffolds thanks to their proven biocompatibility and biostability. Several polymers have been combined with calcium phosphates (mainly hydroxyapatite) to prepare nanocomposites with improved biocompatible and mechanical properties. Here, we report the hydrothermal synthesis in high pressure conditions of nanostructured composites based on hydroxyapatite and polyurethane functionalized with carboxyl and thiol groups. Cell-material interactions were investigated for potential applications of these new types of composites as coating for orthopedic implants. Physical-chemical and morphological characteristics of hydroxyapatite/polyurethane composites were evaluated for different compositions, showing their dependence on synthesis parameters (pressure, temperature). In vitro experiments, performed to verify if these composites are biocompatible cell culture substrates, showed that they are not toxic and do not affect cell viability. PMID:23877879

  12. Development of graded hydroxyapatite/CaCO(3) composite structures for bone ingrowth.

    PubMed

    Heilmann, F; Standard, O C; Müller, F A; Hoffman, M

    2007-09-01

    Ceramic composites composed of constituents with different bone cell reactions present an interesting consideration for a new bone replacement material. The first component of the composite used in this study, hydroxyapatite, is known to be replaced by natural tissue significantly slower than the second, calcium carbonate, which has limited structural stability. A graded hydroxyapatite/calcium carbonate composite with bimodal component distribution was developed using a combined slip infiltration and dip-coating technique from a porous polyurethane sponge replica. A graded hydroxyapatite scaffold with porosities from 5 to 90% was produced and then infiltrated with a calcium carbonate slip and sintered. The resultant composite had improved mechanical properties compared with the monolith as measured by crushing and moduli tests. PMID:17483903

  13. On Ceramics.

    ERIC Educational Resources Information Center

    School Arts, 1982

    1982-01-01

    Presents four ceramics activities for secondary-level art classes. Included are directions for primitive kiln construction and glaze making. Two ceramics design activities are described in which students make bizarrely-shaped lidded jars, feet, and footwear. (AM)

  14. Structural Ceramics

    NASA Technical Reports Server (NTRS)

    1986-01-01

    This publication is a compilation of abstracts and slides of papers presented at the NASA Lewis Structural Ceramics Workshop. Collectively, these papers depict the scope of NASA Lewis' structural ceramics program. The technical areas include monolithic SiC and Si3N4 development, ceramic matrix composites, tribology, design methodology, nondestructive evaluation (NDE), fracture mechanics, and corrosion.

  15. Effect of Hydrothermal Treatment on Sinterability of Hydroxyapatite

    SciTech Connect

    Kawagoe, D.; Fujimori, H.; Goto, S.; Yamasaki, N.; Ioku, K.

    2006-05-15

    Calcium hydroxyapatite, Ca10(PO4)6(OH)2:HA, is the inorganic principle component of natural bones and teeth. It has been already suggested that the amount of OH ion in the crystal structure of HA is closely related to the biocompatibility. The amount of OH ion in current HA, however, has not been controlled. In order to prepare more functional HA ceramics, the amount of OH ion must be controlled. In this study, HA ceramics with different OH amount were prepared from fine HA crystals by spark plasma sintering (SPS). Fine powder of HA was treated hydrothermally at 200 deg. C for 24 h with pH 10 NH3 aqueous solution. The samples were pressed uniaxialy under 60 MPa, and then they were SPS at 800 deg. C, 900 deg. C and 1000 deg. C for 10 min with the heating rate of 25 deg. C{center_dot}min-1. No phases other than HA were revealed by XRD for the starting samples after hydrothermal treatment and samples after sintering by SPS at 800 deg. C, 900 deg. C and 1000 deg. C for 10 min. The quantity of OH ion in HA ceramics sintered by SPS was decreased with increasing temperature of sintering. Transparent HA ceramics were prepared by SPS at 900 deg. C and 1000 deg. C.

  16. Biomimetic hydroxyapatite coating on pore walls improves osteointegration of poly(L-lactic acid) scaffolds.

    PubMed

    Deplaine, H; Lebourg, M; Ripalda, P; Vidaurre, A; Sanz-Ramos, P; Mora, G; Prósper, F; Ochoa, I; Doblaré, M; Gómez Ribelles, J L; Izal-Azcárate, I; Gallego Ferrer, G

    2013-01-01

    Polymer-ceramic composites obtained as the result of a mineralization process hold great promise for the future of tissue engineering. Simulated body fluids (SBFs) are widely used for the mineralization of polymer scaffolds. In this work an exhaustive study with the aim of optimizing the mineralization process on a poly(L-lactic acid) (PLLA) macroporous scaffold has been performed. We observed that when an air plasma treatment is applied to the PLLA scaffold its hydroxyapatite nucleation ability is considerably improved. However, plasma treatment only allows apatite deposition on the surface of the scaffold but not in its interior. When a 5 wt % of synthetic hydroxyapatite (HAp) nanoparticles is mixed with PLLA a more abundant biomimetic hydroxyapatite layer grows inside the scaffold in SBF. The morphology, amount, and composition of the generated biomimetic hydroxyapatite layer on the pores' surface have been analyzed. Large mineralization times are harmful to pure PLLA as it rapidly degrades and its elastic compression modulus significantly decreases. Degradation is retarded in the composite scaffolds because of the faster and extensive biomimetic apatite deposition and the role of HAp to control the pH. Mineralized scaffolds, covered by an apatite layer in SBF, were implanted in osteochondral lesions performed in the medial femoral condyle of healthy sheep. We observed that the presence of biomimetic hydroxyapatite on the pore's surface of the composite scaffold produces a better integration in the subchondral bone, in comparison to bare PLLA scaffolds. PMID:23152082

  17. Laser surface alloying of 316L stainless steel coated with a bioactive hydroxyapatite-titanium oxide composite.

    PubMed

    Ghaith, El-Sayed; Hodgson, Simon; Sharp, Martin

    2015-02-01

    Laser surface alloying is a powerful technique for improving the mechanical and chemical properties of engineering components. In this study, laser surface irradiation process employed in the surface modification off 316L stainless steel substrate using hydroxyapatite-titanium oxide to provide a composite ceramic layer for the suitability of applying this technology to improve the biocompatibility of medical alloys and implants. Fusion of the metal surface incorporating hydroxyapatite-titania ceramic particles using a 30 W Nd:YAG laser at different laser powers, 40, 50 and 70% power and a scan speed of 40 mm s(-1) was observed to adopt the optimum condition of ceramic deposition. Coatings were evaluated in terms of microstructure, surface morphology, composition biocompatibility using XRD, ATR-FTIR, SEM and EDS. Evaluation of the in vitro bioactivity by soaking the treated metal in SBF for 10 days showed the deposition of biomimetic apatite. PMID:25636972

  18. Synthesis and sintering of nanocrystalline hydroxyapatite powders by citric acid sol-gel combustion method

    SciTech Connect

    Han Yingchao; Li Shipu; Wang Xinyu; Chen Xiaoming

    2004-01-03

    The citric acid sol-gel combustion method has been used for the synthesis of nanocrystalline hydroxyapatite (HAP) powder from calcium nitrate, diammonium hydrogen phosphate and citric acid. The phase composition of HAP powder was characterized by X-ray powder diffraction analysis (XRD). The morphology of HAP powder was observed by transmission electron microscope (TEM). The HAP powder has been sintered into microporous ceramic in air at 1200 deg. C with 3 h soaking time. The microstructure and phase composition of the resulting HAP ceramic were characterized by scanning electron microscope (SEM) and XRD, respectively. The physical characterization of open porosity and flexural strength have also been carried out.

  19. Magnesium incorporation into hydroxyapatite.

    PubMed

    Laurencin, Danielle; Almora-Barrios, Neyvis; de Leeuw, Nora H; Gervais, Christel; Bonhomme, Christian; Mauri, Francesco; Chrzanowski, Wojciech; Knowles, Jonathan C; Newport, Robert J; Wong, Alan; Gan, Zhehong; Smith, Mark E

    2011-03-01

    The incorporation of Mg in hydroxyapatite (HA) was investigated using multinuclear solid state NMR, X-ray absorption spectroscopy (XAS) and computational modeling. High magnetic field (43)Ca solid state NMR and Ca K-edge XAS studies of a ∼10% Mg-substituted HA were performed, bringing direct evidence of the preferential substitution of Mg in the Ca(II) position. (1)H and (31)P solid state NMR show that the environment of the anions is disordered in this substituted apatite phase. Both Density Functional Theory (DFT) and interatomic potential computations of Mg-substituted HA structures are in agreement with these observations. Indeed, the incorporation of low levels of Mg in the Ca(II) site is found to be more favourable energetically, and the NMR parameters calculated from these optimized structures are consistent with the experimental data. Calculations provide direct insight in the structural modifications of the HA lattice, due to the strong contraction of the M⋯O distances around Mg. Finally, extensive interatomic potential calculations also suggest that a local clustering of Mg within the HA lattice is likely to occur. Such structural characterizations of Mg environments in apatites will favour a better understanding of the biological role of this cation. PMID:21144581

  20. Cements from nanocrystalline hydroxyapatite.

    PubMed

    Barralet, J E; Lilley, K J; Grover, L M; Farrar, D F; Ansell, C; Gbureck, U

    2004-04-01

    Calcium phosphate cements are used as bone substitute materials because they may be moulded to fill a void or defect in bone and are osteoconductive. Although apatite cements are stronger than brushite cements, they are potentially less resorbable in vivo. Brushite cements are three-component systems whereby phosphate ions and water react with a soluble calcium phosphate to form brushite (CaHPO4 x 2H2O). Previously reported brushite cement formulations set following the mixture of a calcium phosphate, such as beta-tricalcium phosphate (beta-TCP), with an acidic component such as H3PO4 or monocalcium phosphate monohydrate (MCPM). Due to its low solubility, hydroxyapatite (HA) is yet to be reported as a reactive component in calcium phosphate cement systems. Here we report a new cement system setting to form a matrix consisting predominantly of brushite following the mixture of phosphoric acid with nanocrystalline HA. As a result of the relative ease with which ionic substitutions may be made in apatite this route may offer a novel way to control cement composition or setting characteristics. Since kinetic solubility is dependent on particle size and precipitation temperature is known to affect precipitated HA crystal size, the phase composition and mechanical properties of cements made from HA precipitated at temperatures between 4 and 60 degrees C were investigated. PMID:15332608

  1. Hydroxyapatite in Physiological Environment

    NASA Astrophysics Data System (ADS)

    Slepko, Alexander; Demkov, Alexander A.

    2011-03-01

    A carbonated form of hydroxyapatite (HA) [ Ca 10 (PO4)6 (OH)2 ] is one of the most abundant materials in mammal bone. It crystallizes within the spaces between tropocollagen protein chains in an aqueous solution and strengthens the bone tissue. An emerging application of synthetic HA is bone repair and replacement. Bulk electronic and chemical properties of HA were studied theoretically recently. However, the absorption of H2 O molecules and amino acids of the tropocollagen chains at HA surfaces remains an area of active research. Using density functional theory we analyze the electronic properties and surface energetics of HA for different orientations and terminations and generate a theoretical surface phase diagram of HA. The reactivity of these surface models is analyzed using the frontier orbital approach. We find two dominant surfaces which are most stable over the widest chemical range. However, we expect them to show little surface reactivity. Using a HA slab with a highly reactive surface we build atomistic models of HA covered with up to one monolayer of water and analyze interactions between this surface and the water molecules.

  2. Development and study of cement and a phosphocalciques ceramic as medical use

    NASA Astrophysics Data System (ADS)

    Abbaoui, E.; Essaddek, A.; Mejdoubi, E.; Elansari, L. L.; Elgadi, M.; Hammouti, B.

    2005-03-01

    The hydroxyapatite (Ca{10}(PO{4})6(OH){2}) has a structure and a chemical composition very close to those of the mineral phase of calcified tissues. It is thus used for a long time in orthopedic and odontological surgery. In the past few years, cements which evolve toward the hydroxyapatite have been the object of several studies. This communication reports the synthesis and the study of new phosphocalcic cement, which evolves after hardening, towards a hydroxyapatite. The cement is composed of tricalcium phosphate a type (α -Ca{3}(PO{4})2), calcium hydroxide (Ca(OH){2}) and phosphoric acid (H{3}PO{4}). The sintering of hardened cement, leads to ceramics having a structure and chemical composition close to those of the bone's mineral phase. The trisodium phosphate is used as melting agent to increase the hardness of ceramics and to decrease the sintering temperature, without affecting the physicochemical properties of ceramics.

  3. Hydroxyapatite-titanium interface reaction induced by keV electron irradiation

    NASA Astrophysics Data System (ADS)

    Torrisi, L.; Foti, G.

    1992-03-01

    Thin films of hydroxyapatite bioceramic, 5-50 Å in thickness, have been deposited on ion cleaned titanium surfaces to study the chemical-physical adhesion of metal-ceramic interfaces of biomedical devices (orthopaedic and dentistry prosthesis). Film deposition was performed in ultrahigh vacuum condition (10 -10 mbar) using 5 keV argon sputtering of hydroxyapatite matrix; the film thickness was measured in situ with Auger electron spectroscopy. The hydroxyapatite-titanium interface was irradiated with an electron beam of 0.5-5 keV energy and 0.2-2 A/cm 2 current density. During electron irradiation, Auger spectra show chemical shifts of phosphorus, titanium and oxygen peaks. The released electron energy induces modifications in the tetraedric phosphorus-oxygen groups with production of new chemical bonds between phosphorus, oxygen and titanium. Oxygen, for example, diffuses into the titanium interface forming titanium oxide. Chemical reactions induced by electron irradiation are driven by the metal-ceramic interface. Near the interface a strong and fast effect is observed while far from the interface a weak and slow effect occurs. Chemical reactions depend on the electron irradiation dose showing an inhibition threshold at about 10 19 e/cm 2 and, near the interface, a saturation condition at about 5 × 10 20 e/cm 2. Titanium-ceramic chemical reactions are inhibited if the substrate titanium surface is rich in oxide.

  4. Ceramic burner

    SciTech Connect

    Laux, W.; Hebel, R.; Artelt, P.; Esfeld, G.; Jacob, A.

    1981-03-31

    Improvements in the mixing body and supporting structure of a molded-ceramic-brick burner enable the burner to withstand the vibrations induced during its operation. Designed for the combustion chambers of air heaters, the burner has a mixing body composed of layers of shaped ceramic bricks that interlock and are held together vertically by a ceramic holding bar. The mixing body is shaped like a mushroom - the upper layers have a larger radius than the lower ones.

  5. Ceramic Processing

    SciTech Connect

    EWSUK,KEVIN G.

    1999-11-24

    Ceramics represent a unique class of materials that are distinguished from common metals and plastics by their: (1) high hardness, stiffness, and good wear properties (i.e., abrasion resistance); (2) ability to withstand high temperatures (i.e., refractoriness); (3) chemical durability; and (4) electrical properties that allow them to be electrical insulators, semiconductors, or ionic conductors. Ceramics can be broken down into two general categories, traditional and advanced ceramics. Traditional ceramics include common household products such as clay pots, tiles, pipe, and bricks, porcelain china, sinks, and electrical insulators, and thermally insulating refractory bricks for ovens and fireplaces. Advanced ceramics, also referred to as ''high-tech'' ceramics, include products such as spark plug bodies, piston rings, catalyst supports, and water pump seals for automobiles, thermally insulating tiles for the space shuttle, sodium vapor lamp tubes in streetlights, and the capacitors, resistors, transducers, and varistors in the solid-state electronics we use daily. The major differences between traditional and advanced ceramics are in the processing tolerances and cost. Traditional ceramics are manufactured with inexpensive raw materials, are relatively tolerant of minor process deviations, and are relatively inexpensive. Advanced ceramics are typically made with more refined raw materials and processing to optimize a given property or combination of properties (e.g., mechanical, electrical, dielectric, optical, thermal, physical, and/or magnetic) for a given application. Advanced ceramics generally have improved performance and reliability over traditional ceramics, but are typically more expensive. Additionally, advanced ceramics are typically more sensitive to the chemical and physical defects present in the starting raw materials, or those that are introduced during manufacturing.

  6. Ceramic joining

    SciTech Connect

    Loehman, R.E.

    1996-04-01

    This paper describes the relation between reactions at ceramic-metal interfaces and the development of strong interfacial bonds in ceramic joining. Studies on a number of systems are described, including silicon nitrides, aluminium nitrides, mullite, and aluminium oxides. Joints can be weakened by stresses such as thermal expansion mismatch. Ceramic joining is used in a variety of applications such as solid oxide fuel cells.

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

    PubMed

    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. PMID:25910818

  8. Ceramic filters

    SciTech Connect

    Holmes, B.L.; Janney, M.A.

    1995-12-31

    Filters were formed from ceramic fibers, organic fibers, and a ceramic bond phase using a papermaking technique. The distribution of particulate ceramic bond phase was determined using a model silicon carbide system. As the ceramic fiber increased in length and diameter the distance between particles decreased. The calculated number of particles per area showed good agreement with the observed value. After firing, the papers were characterized using a biaxial load test. The strength of papers was proportional to the amount of bond phase included in the paper. All samples exhibited strain-tolerant behavior.

  9. Polymer-ceramic Monolithic In-Needle Extraction (MINE) device: Preparation and examination of drug affinity.

    PubMed

    Pietrzyńska, Monika; Tomczak, Rafał; Jezierska, Katarzyna; Voelkel, Adam; Jampílek, Josef

    2016-11-01

    Polymer-ceramic materials were placed in the in-needle device. Polymer-ceramic Monolithic In-Needle Extraction (MINE) device is an extraction device used in sample preparation step but, on the other hand, it can be a tool for examination of interactions between potential antiresorptive drugs and bones. MINE device was used as tool for determination of bisphosphonate affinity to hydroxyapatite. Spectra of prepared materials containing different proportion of the ceramic part were performed with the use of Fourier transform infrared spectroscopy. The extraction of sodium risedronate as standard compound from simulated body fluids was carried out by pumping liquid samples through the MINE device. The amount of sodium risedronate in solutions was examined using UV-VIS spectroscopy. The sorption results of sodium risedronate obtained for monolithic materials containing different amount of hydroxyapatite were compared to the values determined for pure (bulk) hydroxyapatite. Sorption capacity for polymer-ceramic materials placed in the in-needle extraction device was about 0.39mg of sodium risedronate. The complete desorption process was carried out at the level over 95% using various eluents. The results of sorption-desorption experiments allow to deduce on the affinity of sodium risedronate to the ceramic part of sorbent (hydroxyapatite). PMID:27523998

  10. Coralline hydroxyapatite in complex acetabular reconstruction.

    PubMed

    Wasielewski, Ray C; Sheridan, Kate C; Lubbers, Melissa A

    2008-04-01

    This retrospective study examined whether a coralline hydroxyapatite bone graft substitute adequately repaired bone defects during complex acetabular reconstructions. Seventeen patients who underwent acetabular revision using Pro Osteon 500 were assessed to determine whether any cups required re-revision, whether bone had incorporated into the coralline hydroxyapatite grafts, and whether the coralline hydroxyapatite grafts resorbed with time. At latest follow-up, no cups required re-revision, but 1 had failed. Radiographic evidence of bone incorporation was observed in every coralline hydroxyapatite graft. Graft resorption was not observed. PMID:19292282

  11. Crystallization of modified hydroxyapatite on titanium implants

    NASA Astrophysics Data System (ADS)

    Golovanova, O. A.; Izmailov, R. R.; Ghyngazov, S. A.; Zaits, A. V.

    2016-02-01

    Carbonated-hydroxyapatite (CHA) and Si-hydroxyapatite (Si-HA) precipitation have been synthesized from the model bioliquid solutions (synovial fluid and SBF). It is found that all the samples synthesized from the model solutions are single-phase and represent hydroxyapatite. The crystallization of the modified hydroxyapatite on alloys of different composition, roughness and subjected to different treatment techniques was investigated. Irradiation of the titanium substrates with the deposited biomimetic coating can facilitate further growth of the crystal and regeneration of the surface.

  12. Synthesis and characterization of porous hydroxyapatite and hydroxyapatite coatings

    SciTech Connect

    Nieh, T G; Choi, B W; Jankowski, A F

    2000-10-25

    A technique is developed to construct bulk hydroxyapatite (HAp) with different cellular structures. The technique involves the initial synthesis of nanocrystalline hydroxyapatite powder from an aqueous solution using water-soluble compounds and then followed by spray drying into agglomerated granules. The granules were further cold pressed and sintered into bulks at elevated temperatures. The sintering behavior of the HAp granules was characterized and compared with those previously reported. Resulting from the fact that the starting HAp powders were extremely fine, a relatively low activation energy for sintering was obtained. In the present study, both porous and dense structures were produced by varying powder morphology and sintering parameters. Porous structures consisting of open cells were constructed. Sintered structures were characterized using scanning electron microscopy and x-ray tomography. In the present paper, hydroxyapatite coatings produced by magnetron sputtering on silicon and titanium substrates will also be presented. The mechanical properties of the coatings were measured using nanoindentation techniques and microstructures examined using transmission electron microscopy.

  13. Guided bone augmentation using ceramic space-maintaining devices: the impact of chemistry

    PubMed Central

    Anderud, Jonas; Abrahamsson, Peter; Jimbo, Ryo; Isaksson, Sten; Adolfsson, Erik; Malmström, Johan; Naito, Yoshihito; Wennerberg, Ann

    2015-01-01

    The purpose of the study was to evaluate histologically, whether vertical bone augmentation can be achieved using a hollow ceramic space maintaining device in a rabbit calvaria model. Furthermore, the chemistry of microporous hydroxyapatite and zirconia were tested to determine which of these two ceramics are most suitable for guided bone generation. 24 hollow domes in two different ceramic materials were placed subperiosteal on rabbit skull bone. The rabbits were sacrificed after 12 weeks and the histology results were analyzed regarding bone-to-material contact and volume of newly formed bone. The results suggest that the effect of the microporous structure of hydroxyapatite seems to facilitate for the bone cells to adhere to the material and that zirconia enhance a slightly larger volume of newly formed bone. In conclusion, the results of the current study demonstrated that ceramic space maintaining devices permits new bone formation and osteoconduction within the dome. PMID:25792855

  14. Osteoconductive composite graft based on bacterial synthesized hydroxyapatite nanoparticles doped with different ions: From synthesis to in vivo studies.

    PubMed

    Ahmadzadeh, Elham; Talebnia, Farid; Tabatabaei, Meisam; Ahmadzadeh, Hossein; Mostaghaci, Babak

    2016-07-01

    To repair damaged bone tissues, osteoconductive bone graft substitutes are required for enhancement of the regenerative potential of osteoblast cells. Nanostructured hydroxyapatite is a bioactive ceramic used for bone tissue engineering purposes. In this study, carbonate hydroxyapatite (cHA) and zinc-magnesium substituted hydroxyapatite (Zn-Mg-HA) nanoparticles were synthesized via biomineralization method using Enterobacter aerogenes. The structural phase composition and the morphology of the samples were analyzed using appropriate powder characterization methods. Next, a composite graft was fabricated by using polyvinyl alcohol and both cHA and Zn-Mg-HA samples. In vivo osteogenic potential of the graft was then investigated in a rabbit tibial osteotomy model. Histological, radiological and morphological studies showed that the graft was mineralized by the newly formed bone tissue without signs of inflammation or infection after 4 weeks of implantation. These histomorphometric results suggest that the fabricated graft can function as a potent osteoconductive bone tissue substitute. PMID:26956413

  15. Materials processing and in-vivo animal studies of nitrided hydroxyapatite bioceramics

    NASA Astrophysics Data System (ADS)

    Rashid, Nancy Elizabeth

    2000-10-01

    Calcium phosphate bioceramics are currently being used in medicine and dentistry, for reconstruction or repair of diseased or injured bone, but with limited success. Incorporating nitrogen into phosphate glasses has resulted in improved properties, and it is proposed that similar benefits may be gained from nitriding calcium phosphate bioceramics for bone implants as well. This work focuses on processing of hydroxyapatite and tricalcium phosphate bioceramics nitrided by using solid, liquid, gas and ion sources. These materials were characterized by chemical, structural, mechanical, and biological methods to determine both the material structure and their suitability as implant materials. Calcium nitride and NaPON glass were unsatisfactory sources of nitrogen for hydroxyapatite (HA) and/or tricalcium phosphate (TCP) ceramics. Calcium nitride, Ca3N2, is reacts with water vapor in the air, releasing ammonia, and leaving behind crystals of calcium oxide, CaO. The calcium oxide byproduct decreases the chemical stability of hydroxyapatite and HA/TCP composites in simulated body fluid. Sodium phosphorus oxynitride (NaPON) glass, in the form of a liquid sintering aid for HA, produces an inhomogeneous, composite as well. Hydroxyapatite heated at 800C in an ammonia atmosphere produces a homogeneous material with up to 2 wt% N. Infrared spectroscopy indicates cyanamide ions, CN22-, are formed by the incorporated nitrogen and impurity carbon. The use of 15N-doped ammonia results in an 15N NMR peak at 83.2 ppm, indicating P--N bonding. Raman spectroscopy may also indicate P--N bonding, but it is inconclusive. In a limited study, nitrogen may decrease the hardness and fracture toughness of the phosphate ceramic, hydroxyapatite, contrary to results expected for nitrogen in phosphate glasses. Nitrogen ions are incorporated in hydroxyapatite by ion implantation, with lower energies producing higher nitrogen contents. The highest concentration achieved was 3.55 wt% N, as determined

  16. Intrinsic magnetism and hyperthermia in bioactive Fe-doped hydroxyapatite.

    PubMed

    Tampieri, Anna; D'Alessandro, Teresa; Sandri, Monica; Sprio, Simone; Landi, Elena; Bertinetti, Luca; Panseri, Silvia; Pepponi, Giancarlo; Goettlicher, Joerg; Bañobre-López, Manuel; Rivas, Jose

    2012-02-01

    The use of magnetic activation has been proposed to answer the growing need for assisted bone and vascular remodeling during template/scaffold regeneration. With this in mind, a synthesis procedure was developed to prepare bioactive (Fe2+/Fe3+)-doped hydroxyapatite (Fe-HA), endowed with superparamagnetic-like properties. This new class of magnetic hydroxyapatites can be potentially employed to develop new magnetic ceramic scaffolds with enhanced regenerative properties for bone surgery; in addition, magnetic Fe-HA can find application in anticancer therapies, to replace the widely used magnetic iron oxide nanoparticles, whose long-term cytotoxicity was recently found to reach harmful levels. An extensive physicochemical, microstructural and magnetic characterization was performed on the obtained Fe-HA powders, and demonstrated that the simultaneous addition of Fe2+ and Fe3+ ions during apatite nucleation under controlled synthesis conditions induces intrinsic magnetization in the final product, minimizing the formation of magnetite as secondary phase. This result potentially opens new perspectives for biodevices aimed at bone regeneration and for anti-cancer therapies based on hyperthermia. PMID:22005331

  17. Alkoxide route for preparing hydroxyapatite and its coatings.

    PubMed

    Weng, W; Baptista, J L

    1998-01-01

    The preparation of hydroxyapatite using n-butanol or ethanol solutions of P2O5 and Ca glycoxide as precursors of P and Ca was investigated by nuclear magnetic resonance (NMR), X-Ray Diffraction (XRD) and Scanning Electron Microscopy (SEM). Stable mixed solutions of the precursors could be obtained in the presence of acetic acid (HOAC). For the mixed solution of Ca glycoxide with the ethanol solution of P2O5, a lower HOAC/Ca ratio was needed since the ethanol solution of P2O5 contained a lower concentration of H3PO4, a species that easily forms precipitates in the presence of the Ca containing species. An amorphous powder was obtained by heating the stable solution of Ca glycoxide and PO(OH)x(OEt)3-x with an HOAC/Ca ratio of 4 in a hot plate at approximately 150 degrees C. Hydroxyapatite (HAP) was directly formed after calcining the amorphous powder at 500 degrees C. The stable mixed solutions of Ca glycoxide and the alcoholic solutions of P2O5 were used to prepare HAP coatings on alumina substrates using a dip-coating method. The resulting ceramic coatings have a rough surface and an adhesion strength of about 10 MPa. The morphology of the coatings is dependent on the preparation chemistry. PMID:9678859

  18. Dielectric relaxation in monoclinic hydroxyapatite: Observation of hydroxide ion dipoles

    NASA Astrophysics Data System (ADS)

    Horiuchi, N.; Wada, N.; Nozaki, K.; Nakamura, M.; Nagai, A.; Yamashita, K.

    2016-02-01

    We prepared monoclinic hydroxyapatite (HAp) ceramics and measured their dielectric properties. The dielectric dispersion that was observed in the monoclinic HAp consisted of two different relaxations and could be expressed by a summation of two Debye-like relaxations. One relaxation was ascribed to the reorientational motions of OH- ions. The temperature dependence of the relaxation time obeyed the Arrhenius equation. The relaxation time decreased with temperature but decreased discontinuously at 483 K, the monoclinic-hexagonal phase transition temperature of HAp. Correspondingly, the activation energy changed from 0.74 eV for the monoclinic phase to 0.43 eV for the hexagonal phase. The results suggest that the mobility of the OH- ions increases discontinuously with the phase transition to hexagonal HAp. However, critical phenomena, such as critical slowing down, were not observed.

  19. Hydroxyapatite/metal composite coatings formed by electrocodeposition.

    PubMed

    Dasarathy, H; Riley, C; Coble, H D; Lacefield, W R; Maybee, G

    1996-05-01

    Early bone infusion by cementless fixation of composite orthopedic and dental implants consisting of metallic substrates and bioceramics is well documented. Calcium phosphate ceramics in general and hydroxyapatite (HA) in particular have been the most popular of the bioceramics used for coating metals. Here, a non-line of sight coating procedure by electrocodeposition is reported for mechanically fixing HA particles in a metal matrix. Analyses of the coating showed excellent adhesion to the substrate and no structural transformation in either crystallinity or stoichiometry. Adhesion and surface coverage of HA depended upon the particle size. As a demonstration of the coating procedure's non-line of sight applicability, it was successfully used to coat titanium rods sintered with small titanium spheres. PMID:8731152

  20. Heat treatment's effects on hydroxyapatite powders in water vapor and air atmosphere

    NASA Astrophysics Data System (ADS)

    Karabulut, A.; Baştan, F. E.; Erdoǧan, G.; Üstel, F.

    2015-03-01

    Hydroxyapatite (HA; Ca10(PO4)6(OH)2) is the main chemical constituent of bone tissue (~70%) as well as HA which is a calcium phosphate based ceramic material forms inorganic tissue of bone and tooth as hard tissues is used in production of prosthesis for synthetic bone, fractured and broken bone restoration, coating of metallic biomaterials and dental applications because of its bio compatibility. It is known that Hydroxyapatite decomposes with high heat energy after heat treatment. Therefore hydroxyapatite powders that heated in water vapor will less decomposed phases and lower amorphous phase content than in air atmosphere. In this study high purity hydroxyapatite powders were heat treated with open atmosphere furnace and water vapor atmosphere with 900, 1000, 1200 °C. Morphology of same powder size used in this process by SEM analyzed. Chemical structures of synthesized coatings have been examined by XRD. The determination of particle size and morphological structure of has been characterized by Particle Sizer, and SEM analysis, respectively. Weight change of sample was recorded by thermogravimetric analysis (TGA) during heating and cooling.

  1. High-solid-content hydroxyapatite slurry for the production of bone substitute scaffolds.

    PubMed

    Cunningham, E; Dunne, N; Walker, G; Buchanan, F

    2009-08-01

    Key to various bone substitute scaffold production techniques is the development of free-flowing ceramic slurry with optimum theological properties. The aim is to achieve a colloidal suspension with as high a solid content as possible while maintaining a low viscosity which easily penetrates the pores of relevant sacrificial templates. The following investigation describes the optimization of a hydroxyapatite slip and demonstrates its potential application in scaffold production. Using predominantly spherical particles of hydroxyapatite of between 0.82 microm and 16.2 microm, coupled with a 2 wt % addition of the anionic polyelectrolyte, ammonium polyacrylate, an 80 wt % (55.9 vol%) hydroxyapatite solid loaded slip with a viscosity of approximately 126mPas has been developed. Its ability to infiltrate and replicate porous preforms has been shown using polyurethane foam. The enhanced particle packing achieved has allowed for the production of scaffolds with highly dense and uniform grain structures. The results represent a significant improvement in current slurry production techniques and can be utilized to develop high-density ceramic bone substitute scaffolds. PMID:19743638

  2. Ceramic Powders

    NASA Technical Reports Server (NTRS)

    1984-01-01

    In developing its product line of specialty ceramic powders and related products for government and industrial customers, including companies in the oil, automotive, electronics and nuclear industries, Advanced Refractory Technologies sought technical assistance from NERAC, Inc. in specific areas of ceramic materials and silicon technology, and for assistance in identifying possible applications of these materials in government programs and in the automotive and electronics industry. NERAC conducted a computerized search of several data bases and provided extensive information in the subject areas requested. NERAC's assistance resulted in transfer of technologies that helped ART staff develop a unique method for manufacture of ceramic materials to precise customer specifications.

  3. Joining of ceramics of different biofunction by hot isostatic pressing

    SciTech Connect

    Li, Jianguo . Center for Dental Technology and Biomaterials); Harmansson, L. ); Soeremark, R. . Dept. of Prosthodontics)

    1993-10-01

    Monolithic zirconia (Z) and zirconia-hydroxyapatite (Z/HA) composites were joined by cold isostatic pressing (CIP at 300 MPa) and subsequently by glass-encapsulated hot isostatic pressing (HIP at 1225 C, 1 h and 200 MPa). The physical and mechanical properties of the materials were measured. The fracture surface was studied using a light microscope. The results indicate a strength level of the joint similar to that of the corresponding composite material (Z/HA), 845 and 860 MPa, respectively. Similar experiments with monolithic alumina (A) and alumina-hydroxyapatite (A/HA) were carried out without success. Cracking occurred in the joint area during the cold isostatic pressing process. It seems that ceramics with high green strength and similar green density are essential when joining ceramics by combined CIP and HIP processes.

  4. Calcining influence on the powder properties of hydroxyapatite.

    PubMed

    Patel, N; Gibson, I R; Ke, S; Best, S M; Bonfield, W

    2001-02-01

    The effect of different calcination temperatures on the powder characteristics and the sintered density of synthetic hydroxyapatite (HA) powders, produced using two different processing routes, was examined. Powders were produced by either drying, milling and sieving an as-precipitated HA or by spray-drying a slurry of precipitated HA. Calcining the two powders at temperatures between 400 and 1000 degrees C did not significantly affect the powder particle size. The specific surface areas of the two powders, however, were reduced from 70-80 m2/g for a calcination temperature of 400 degrees C to approximately 5-7 m2/g for 1000 degrees C. Analysis of the surfaces of the HA powders using scanning electron microscopy (SEM) illustrated the coarsening and subsequent sintering of the sub-micron crystallites that constitute a powder particle as the calcination temperature increased, corresponding to the decrease in surface area of the powders. The sintered densities of the final ceramics were not significantly affected by calcining the powders. Microhardness measurements of ceramics prepared from powders calcined at different temperatures showed no significant variations with calcination temperature or powder processing method. The results of this study have illustrated that for applications where HA may be used in powder form, for example in plasma-spraying and for the production of HA-polymer composites, calcining the HA will significantly affect the powder properties, namely the surface area and morphology of the powders. For applications requiring HA in a dense ceramic form, for example as granules or blocks, calcining the powders does not significantly affect the properties of the final ceramic. PMID:15348326

  5. Processing ceramics

    NASA Technical Reports Server (NTRS)

    Moritoki, M.; Fujikawa, T.; Miyanaga, J.

    1984-01-01

    A method of hot hydrostatic pressing of ceramics is described. A detailed description of the invention is given. The invention is explained through an example, and a figure illustrates the temperature and pressure during the hot hydrostatic pressing treatment.

  6. Influence of Fe3O4 Nanoparticles in Hydroxyapatite Scaffolds on Proliferation of Primary Human Fibroblast Cells

    NASA Astrophysics Data System (ADS)

    Maleki-Ghaleh, H.; Aghaie, E.; Nadernezhad, A.; Zargarzadeh, M.; Khakzad, A.; Shakeri, M. S.; Beygi Khosrowshahi, Y.; Siadati, M. H.

    2016-05-01

    Modern techniques for expanding stem cells play a substantial role in tissue engineering: the raw material that facilitates regeneration of damaged tissues and treats diseases. The environmental conditions and bioprocessing methods are the primary determinants of the rate of cultured stem cell proliferation. Bioceramic scaffolds made of calcium phosphate are effective substrates for optimal cell proliferation. The present study investigates the effects of two bioceramic scaffolds on proliferating cells in culture media. One scaffold was made of hydroxyapatite and the other was a mixture of hydroxyapatite and ferromagnetic material (Fe3O4 nanoparticles). Disk-shaped (10 mm × 2 mm) samples of the two scaffolds were prepared. Primary human fibroblast proliferation was 1.8- and 2.5-fold faster, respectively, when cultured in the presence of hydroxyapatite or ferrous nanoparticle/hydroxyapatite mixtures. Optical microscopy images revealed that the increased proliferation was due to enhanced cell-cell contact. The presence of magnetic Fe3O4 nanoparticles in the ceramic scaffolds significantly increased cell proliferation compared to hydroxyapatite scaffolds and tissue culture polystyrene.

  7. Influence of Fe3O4 Nanoparticles in Hydroxyapatite Scaffolds on Proliferation of Primary Human Fibroblast Cells

    NASA Astrophysics Data System (ADS)

    Maleki-Ghaleh, H.; Aghaie, E.; Nadernezhad, A.; Zargarzadeh, M.; Khakzad, A.; Shakeri, M. S.; Beygi Khosrowshahi, Y.; Siadati, M. H.

    2016-06-01

    Modern techniques for expanding stem cells play a substantial role in tissue engineering: the raw material that facilitates regeneration of damaged tissues and treats diseases. The environmental conditions and bioprocessing methods are the primary determinants of the rate of cultured stem cell proliferation. Bioceramic scaffolds made of calcium phosphate are effective substrates for optimal cell proliferation. The present study investigates the effects of two bioceramic scaffolds on proliferating cells in culture media. One scaffold was made of hydroxyapatite and the other was a mixture of hydroxyapatite and ferromagnetic material (Fe3O4 nanoparticles). Disk-shaped (10 mm × 2 mm) samples of the two scaffolds were prepared. Primary human fibroblast proliferation was 1.8- and 2.5-fold faster, respectively, when cultured in the presence of hydroxyapatite or ferrous nanoparticle/hydroxyapatite mixtures. Optical microscopy images revealed that the increased proliferation was due to enhanced cell-cell contact. The presence of magnetic Fe3O4 nanoparticles in the ceramic scaffolds significantly increased cell proliferation compared to hydroxyapatite scaffolds and tissue culture polystyrene.

  8. Bioinspired Hydroxyapatite/Poly(methyl methacrylate) Composite with a Nacre-Mimetic Architecture by a Bidirectional Freezing Method.

    PubMed

    Bai, Hao; Walsh, Flynn; Gludovatz, Bernd; Delattre, Benjamin; Huang, Caili; Chen, Yuan; Tomsia, Antoni P; Ritchie, Robert O

    2016-01-01

    Using a bidirectional freezing technique, combined with uniaxial pressing and in situ polymerization, "nacre-mimetic" hydroxyapatite/poly(methyl methacrylate) (PMMA) composites are developed by processing large-scale aligned lamellar ceramic scaffolds. Structural and mechanical characterization shows "brick-and-mortar" structures, akin to nacre, with interesting combinations of strength, stiffness, and work of fracture, which provide a pathway to making strong and tough lightweight materials. PMID:26554760

  9. Dissolution of synthetic and bovine bone-derived hydroxyapatites fabricated by hot-pressing

    NASA Astrophysics Data System (ADS)

    Kim, Young Gook; Seo, Dong Seok; Lee, Jong Kook

    2008-11-01

    Dissolving behavior of hydroxyapatite (HA) ceramics prepared from bovine bone (BHA) was investigated and compared with synthetic HA. BHA power was obtained by calcining at 800 °C for 1 h to remove organics and then attritor-milling for 24 h. Synthetic HA and BHA powders were prepared by hot-pressing at 1000 °C for 0.5 h under the pressure of 30 MPa in Ar atmosphere. Sintered densities of the synthetic HA and the BHA were about 96% and 95%, respectively. The BHA consisted of mainly HA and small amount of magnesium oxide. Immersion test revealed that there was no clear evidence of dissolution for the BHA, whereas extensive dissolution on the surface of the synthetic HA occurred in buffered water. Accordingly, dense hydroxyapatite from bovine bone was more stable than synthetic HA in liquid environment.

  10. Analysis of the deposition of biocompatible hydroxyapatite coatings enriched with AgNO3

    NASA Astrophysics Data System (ADS)

    Studený, Zbyněk

    2011-12-01

    Armies of NATO countries are involved in foreign operations, where there are great risks of injuries during combat operations. In addition to other injuries soldiers may suffer infraction or destruction of bones or their parts. Research in the use of biocompatible materials finds solutions to successfully restore this harm. This article deals with the evaluation methods that are typical of hydroxyapatite biocompatible coating. This coating with its poor mechanical properties must be deposited on the base, which also must be biocompatible. In order to get perfect bonding with the natural bone, it is necessary to have the titanium implant surface covered by bio-ceramics coating, which is similar to human bone - hydroxyapatite-like coating.

  11. Structural Ceramics Database

    National Institute of Standards and Technology Data Gateway

    SRD 30 NIST Structural Ceramics Database (Web, free access)   The NIST Structural Ceramics Database (WebSCD) provides evaluated materials property data for a wide range of advanced ceramics known variously as structural ceramics, engineering ceramics, and fine ceramics.

  12. Effect of sintered silicate-substituted hydroxyapatite on remodelling processes at the bone-implant interface.

    PubMed

    Porter, Alexandra E; Patel, Nelesh; Skepper, Jeremy N; Best, Serena M; Bonfield, William

    2004-07-01

    Phase pure, sintered granules of hydroxyapatite (HA) and silicon-substituted hydroxyapatite (Si-HA) were implanted for 6 and 12 weeks in an ovine model. Samples containing the bone-implant interface were prepared for ultramicrotomy and transmission electron microscopy (TEM) using an anhydrous sample preparation procedure. The results demonstrate that the morphology of apatite deposits and the sequence of events at the interfaces of bone with pure HA and with Si-HA implants, were different. Organised collagen fibrils were first found at the bone/Si-HA interface after 6 weeks, whereas they were found only after 12 weeks around the pure HA implant. Many more nodular aggregates comprised of plate-like apatite crystallites were observed in the vicinity of Si-HA than around the pure HA after 12 weeks in vivo. These findings suggest that the incorporation of silicate ions into HA promotes processes of bone remodelling at the bone/HA interface. TEM observations suggested that the trabecular bone weaves over the Si-HA and that the collagen fibrils form a mechanical interlock with the Si-HA ceramic implants. High-resolution lattice imaging illustrated apatite crystallites contiguous with the Si-HA ceramic and revealed a direct relationship between the bone mineral and the Si-HA ceramic. PMID:14980425

  13. New experience with alumina-on-alumina ceramic bearings for total hip arthroplasty.

    PubMed

    D'Antonio, James; Capello, William; Manley, Michael; Bierbaum, Benjamin

    2002-06-01

    A major challenge for total hip arthroplasty is to minimize wear and osteolysis in young, active patients. Alumina ceramic bearings have shown superior wear resistance and lubrication and do not carry the risk of ion release. In a prospective randomized study, 514 hips were implanted. All patients (average age, 53 years) received the same press-fit hydroxyapatite coated femoral stem; two thirds (345 hips) received alumina ceramic bearings, and one third (169 hips) received a cobalt-chrome-on-polyethylene bearing. At a mean follow-up of 35.2 months (range, 24-48 months), there was no significant difference in clinical performance between the patient cohorts. No ceramic fracture or alumina ceramic bearing failure occurred. This new experience involves the use of improved ceramic materials and new design considerations that eliminate the risks and complications of past experiences with ceramic implants and provides a safe bearing option for young patients. PMID:12066265

  14. Effects of ethanol on the osteogenesis around porous hydroxyapatite implants.

    PubMed

    Lima, C C; Silva, T D; Santos, L; Nakagaki, W R; Loyola, Y C S; Resck, M C C; Camilli, J A; Soares, E A; Garcia, J A D

    2011-02-01

    Alcohol consumption compromises bone tissue, and thus may either impair or stop the fixation and maintenance of osseointegrated implants. To evaluate the effects of 5% and 15% ethanol on bone neoformation around porous hydroxiapatite implants. Fifteen rats were separated into 3 groups of 5 animals each: control (CT); 5% alcohol (A); and 15% alcohol (AA). After four weeks of ethanol consumption, the rats received porous hydroxiapatite implants into surgically made cavities in the femur. After surgery, the animals continued to consume ethanol until day 90 of the experiment, when they were euthanised and their femurs removed for histological processing. Bone tissue was found around the ceramic specimens of all the animals. The largest volume of neoformed bone around ceramic specimens occurred in the CT group, and the smallest in the AA group, followed by the A group. It was concluded that ethanol consumption produced a negative effect on osteogenesis around hydroxyapatite implants. Even small doses, such as the 5% ethanol dilution can interfere with bone repair. PMID:21437407

  15. Interfacial stress transfer in a graphene nanosheet toughened hydroxyapatite composite

    NASA Astrophysics Data System (ADS)

    Zhang, L.; Zhang, X. G.; Chen, Y.; Su, J. N.; Liu, W. W.; Zhang, T. H.; Qi, F.; Wang, Y. G.

    2014-10-01

    In recent years, graphene has emerged as potential reinforcing nanofiller in the composites for structural engineering due to its extraordinary high elastic modulus and mechanical strength. As recognized, the transfer of stress from a low modulus matrix to a high-modulus reinforcing graphene and the interfacial behavior at a graphene-matrix interface is the fundamental issue in these composites. In the case of graphene nanosheet (GNS) reinforced hydroxyapatite (HA) composite, this research presented analytical models and simulated that the number of graphene layers of GNSs has little effect on the maximum axial stress (˜0.35 GPa) and the maximum shear stress (˜0.14 GPa) at a GNS-HA interface, and the energy dissipation by GNS pull-out decreases with increasing the number of graphene layers due to weak bonding between them. Also, GNS-HA interfacial delamination and/or GNS rupture were also indentified to be the two key failure mechanisms. The computed results are expected to facilitate a better understanding of the interfacial behavior at a GNS-ceramic interface and to achieve tough ceramics reinforced with GNSs.

  16. Formation of Solution-derived Hydroxyapatite Coatings on Titanium Alloy in the Presence of Magnetron-sputtered Alumina Bond Coats

    PubMed Central

    Zykova, Anna; Safonov, Vladimir; Yanovska, Anna; Sukhodub, Leonid; Rogovskaya, Renata; Smolik, Jerzy; Yakovin, Stas

    2015-01-01

    Hydroxyapatite Ca10(PO4)6(OH)2 (HAp) and calcium phosphate ceramic materials and coatings are widely used in medicine and dentistry because of their ability to enhance the tissue response to implant surfaces and promote bone ingrowth and osseoconduction processes. The deposition conditions have a great influence on the structure and biofunctionality of calcium phosphate coatings. Corrosion processes and poor adhesion to substrate material reduce the lifetime of implants with calcium phosphate coatings. The research has focused on the development of advanced methods to deposit double-layered ceramic oxide/calcium phosphate coatings by a hybrid technique of magnetron sputtering and thermal methods. The thermal method can promote the crystallization and the formation of HAp coatings on titanium alloy Ti6Al4V substrates at low temperature, based on the principle that the solubility of HAp in aqueous solutions decreases with increasing substrate temperature. By this method, hydroxyapatite directly coated the substrate without precipitation in the initial solution. Using a thermal substrate method, calcium phosphate coatings were prepared at substrate temperatures of 100-105 oC. The coated metallic implant surfaces with ceramic bond coats and calcium phosphate layers combine the excellent mechanical properties of metals with the chemical stability of ceramic materials. The corrosion test results show that the ceramic oxide (alumina) coatings and the double-layered alumina-calcium phosphate coatings improve the corrosion resistance compared with uncoated Ti6Al4V and single-layered Ti6Al4V/calcium phosphate substrates. In addition, the double-layered alumina/hydroxyapatite coatings demonstrate the best biocompatibility during in vitro tests. PMID:25893018

  17. Formation of Solution-derived Hydroxyapatite Coatings on Titanium Alloy in the Presence of Magnetron-sputtered Alumina Bond Coats.

    PubMed

    Zykova, Anna; Safonov, Vladimir; Yanovska, Anna; Sukhodub, Leonid; Rogovskaya, Renata; Smolik, Jerzy; Yakovin, Stas

    2015-01-01

    Hydroxyapatite Ca10(PO4)6(OH)2 (HAp) and calcium phosphate ceramic materials and coatings are widely used in medicine and dentistry because of their ability to enhance the tissue response to implant surfaces and promote bone ingrowth and osseoconduction processes. The deposition conditions have a great influence on the structure and biofunctionality of calcium phosphate coatings. Corrosion processes and poor adhesion to substrate material reduce the lifetime of implants with calcium phosphate coatings. The research has focused on the development of advanced methods to deposit double-layered ceramic oxide/calcium phosphate coatings by a hybrid technique of magnetron sputtering and thermal methods. The thermal method can promote the crystallization and the formation of HAp coatings on titanium alloy Ti6Al4V substrates at low temperature, based on the principle that the solubility of HAp in aqueous solutions decreases with increasing substrate temperature. By this method, hydroxyapatite directly coated the substrate without precipitation in the initial solution. Using a thermal substrate method, calcium phosphate coatings were prepared at substrate temperatures of 100-105 (o)C. The coated metallic implant surfaces with ceramic bond coats and calcium phosphate layers combine the excellent mechanical properties of metals with the chemical stability of ceramic materials. The corrosion test results show that the ceramic oxide (alumina) coatings and the double-layered alumina-calcium phosphate coatings improve the corrosion resistance compared with uncoated Ti6Al4V and single-layered Ti6Al4V/calcium phosphate substrates. In addition, the double-layered alumina/hydroxyapatite coatings demonstrate the best biocompatibility during in vitro tests. PMID:25893018

  18. Ceramics Analysis

    NASA Technical Reports Server (NTRS)

    1996-01-01

    Lewis Research Center developed the CARES/LIFE software, which predicts the performance of brittle structures over time, such as ceramic compounds. Over 300 companies have used a version of the code, including Philips Display Components Company, AlliedSignal, Solar Turbines Incorporated, and TRW, Inc. for everything from engines to television tubes. The software enables a designer to test a variety of configurations for probability of failure and to adjust the structure's geometry to minimize the predicted failure or maximize durability for the lifetime of the ceramic component.

  19. Design of novel plasma sprayed hydroxyapatite-bond coat bioceramic systems

    NASA Astrophysics Data System (ADS)

    Heimann, R. B.

    1999-12-01

    Bond coats based on bioinert ceramic materials such as titania and zirconia were developed to increase the adhesion strength of the coating system hydroxyapatite-bond coat to Ti-6Al-4V alloy surfaces used for hip endoprostheses and dental root implants. The bond coats improved the adhesion strength, measured by a modified ASTM D 3167-76 peel test, by up to 100% and also the resorption resistance as determined by in vitro leaching in simulated protein-free body fluid for up to 28 days.

  20. Microwave systems for the processing of advanced ceramics

    SciTech Connect

    Wilson, O. Jr.; Carmel, Y.; Lloyd, I.

    1999-07-01

    Microwave processing systems are continually evolving to incorporate more unique capabilities and design features. These new developments are instrumental in expanding the scope of microwave systems for studying complex phenomena in materials synthesis and processing. On a more fundamental level, questions concerning the nature of interactions between microwaves and ceramic materials systems can be addressed to provide direct impact on processing strategies for advanced ceramic materials. A novel microwave processing system is being developed to study fundamental issues in the sintering of advanced ceramic materials with enhanced dielectric, thermal, optical, and mechanical properties for applications in microelectronics, biomaterials, and structural applications. The system consists of a single and dual frequency microwave furnace that operates at 2.45 and 28 GHz, an optical pyrometric temperature measuring system, and an optical, non-invasive, non-contact, extensometer for measuring sintering shrinkage and kinetics. The additional ability to process at 28 GHz provides opportunities to sinter a wider range of ceramic materials by direct coupling. An even more exciting benefit of the dual frequency system is the potential to process ceramics at two frequencies simultaneously. This capability can provide a unique way to tailor the microstructure of advanced ceramics by controlling the extent of both volumetric and surface heating. Experimental results for microwave sintering studies involving ZnO, hydroxyapatite, AlN-SiC composites, and alumina composites will be presented, with an emphasis on the processing of nanograin ceramics. In particular, the role of surface modification and microwave field intensification effects will be discussed.

  1. On the anisotropic elastic properties of hydroxyapatite.

    NASA Technical Reports Server (NTRS)

    Katz, J. L.; Ukraincik, K.

    1971-01-01

    Experimental measurements of the isotropic elastic moduli on polycrystalline specimens of hydroxyapatite and fluorapatite are compared with elastic constants measured directly from single crystals of fluorapatite in order to derive a set of pseudo single crystal elastic constants for hydroxyapatite. The stiffness coefficients thus derived are given. The anisotropic and isotropic elastic properties are then computed and compared with similar properties derived from experimental observations of the anisotropic behavior of bone.

  2. Detection of Hydroxyapatite in Calcified Cardiovascular Tissues

    PubMed Central

    Lee, Jae Sam; Morrisett, Joel D.; Tung, Ching-Hsuan

    2012-01-01

    Objective The objective of this study is to develop a method for selective detection of the calcific (hydroxyapatite) component in human aortic smooth muscle cells in vitro and in calcified cardiovascular tissues ex vivo. This method uses a novel optical molecular imaging contrast dye, Cy-HABP-19, to target calcified cells and tissues. Methods A peptide that mimics the binding affinity of osteocalcin was used to label hydroxyapatite in vitro and ex vivo. Morphological changes in vascular smooth muscle cells were evaluated at an early stage of the mineralization process induced by extrinsic stimuli, osteogenic factors and a magnetic suspension cell culture. Hydroxyapatite components were detected in monolayers of these cells in the presence of osteogenic factors and a magnetic suspension environment. Results Atherosclerotic plaque contains multiple components including lipidic, fibrotic, thrombotic, and calcific materials. Using optical imaging and the Cy-HABP-19 molecular imaging probe, we demonstrated that hydroxyapatite components could be selectively distinguished from various calcium salts in human aortic smooth muscle cells in vitro and in calcified cardiovascular tissues, carotid endarterectomy samples and aortic valves, ex vivo. Conclusion Hydroxyapatite deposits in cardiovascular tissues were selectively detected in the early stage of the calcification process using our Cy-HABP-19 probe. This new probe makes it possible to study the earliest events associated with vascular hydroxyapatite deposition at the cellular and molecular levels. This target-selective molecular imaging probe approach holds high potential for revealing early pathophysiological changes, leading to progression, regression, or stabilization of cardiovascular diseases. PMID:22877867

  3. A new approach to enhancement of bone formation by electrically polarized hydroxyapatite.

    PubMed

    Teng, N C; Nakamura, S; Takagi, Y; Yamashita, Y; Ohgaki, M; Yamashita, K

    2001-10-01

    An electrical field may affect osteogenesis. Since we found that hydroxyapatite (HA) ceramics may be polarizable, we hypothesized that electrically polarized HA may foster production of new bone in vivo. Both polarized and non-polarized HA ceramics were inserted into the subperiosteum spaces at the parietal bone area of rats. After 2, 4, and 8 weeks, the implant sites were examined histologically. Morphometric analysis revealed that new bone formation was accelerated on the negatively charged surface of the polarized HA (N-surface) at 2 weeks. The newly formed bone approached maturation at 4 weeks and was thicker on the N-surface than in the controls. By 8 weeks, newly formed bone in the controls was almost the same as that on the N-surface. These findings suggest that polarized HA is biocompatible and that bone formation on the N-surface is enhanced in the early stage of bone healing. PMID:11706953

  4. Influence of pentavalent dopant addition to polarization and bioactivity of hydroxyapatite.

    PubMed

    Dhal, Jharana; Bose, Susmita; Bandyopadhyay, Amit

    2013-07-01

    Influence of pentavalent tantalum doping in bulk hydroxyapatite (HAp) ceramics has been investigated for polarizability and bioactivity. Phase analysis from X-ray diffraction measurement indicates that increasing dopant concentration decreased the amount of HAp phase and increased β-TCP and/or α-TCP phases during sintering at 1250 °C in a muffle furnace. Results from thermally stimulated depolarization current (TSDC) measurements showed that doping hindered charge storage ability in HAp ceramics, and doped samples stored fewer charge compared to pure HAp. However, doping enhanced wettability of HAp samples, which was improved further due to polarization. In vitro human osteoblast cell-material interaction study revealed an increase in bioactivity due to dopant addition and polarization compared to pure HAp. This increase in bioactivity was attributed to the increase in wettability due to surface charge and dopant addition. PMID:23623133

  5. Synthesis, mechanical and biological characterization of ionic doped carbonated hydroxyapatite/β-tricalcium phosphate mixtures.

    PubMed

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

    2011-04-01

    The influence of ionic substituents in calcium phosphates intended for bone and tooth replacement biomedical applications is an important research topic, owing to the essential roles played by trace elements in biological processes. The present study investigates the mechanical and biological evaluation of ionic doped hydroxyapatite/β-tricalcium phosphate mixtures which have been prepared by a simple aqueous precipitation method. Heat treating the resultant calcium phosphates in a carbonated atmosphere led to the formation of ionic doped carbonated hydroxyapatite/β-tricalcium phosphate mixtures containing the essential ions of biological apatite. The structural analysis determined by Rietveld refinement confirmed the presence of hydroxyapatite as the main phase, together with a considerable amount of β-tricalcium phosphate. Such phase assemblage is essentially due to the influence of substituted ions during synthesis. The results from mechanical tests proved that carbonate substitutions are detrimental for the mechanical properties of apatite-based ceramics. In vitro proliferation assays of osteoblastic-like cells (MC3T3-E1 cell line) to powders revealed that carbonate incorporation can either delay or accelerate MC3T3 proliferation, although reaching the same proliferation levels as control cells after 2 weeks in culture. Further, the powders enable pre-osteoblastic differentiation in a similar manner to control cells, as indirectly measured by ALP activity and Type-I collagen medium secretion. PMID:21146640

  6. Preparation and characterization of magnesium/carbonate co-substituted hydroxyapatites.

    PubMed

    Gibson, I R; Bonfield, W

    2002-07-01

    A new synthesis/processing method has been devised to produce magnesium/carbonate co-substituted hydroxyapatite ceramics that do not decompose to tricalcium phosphate (TCP) on sintering. Using this method, a series of magnesium/carbonate co-substituted hydroxyapatite (Mg/CO(3)-HA) compositions, containing between 0 and 0.35 wt % Mg and approximately 0.9 wt % CO(3) were prepared. Sintering the Mg/CO(3)-HA compositions in a CO(2)/H(2)O atmosphere yields a single crystalline phase that appears to be identical to stoichiometric HA. In contrast, when the compositions were prepared in the absence of carbonate and were sintered in air, the phase composition was a biphasic mixture of HA and TCP e.g. for 0.25 wt % Mg substitution the phase composition was approximately 60%HA/40% TCP. Clearly, both the synthesis route and the processing (i.e. sintering) route are of importance in the production of a single-phase Mg/CO(3)-HA ceramic. Fourier transform infrared (FTIR) spectroscopy has indicated that the Mg/CO(3)-HA ceramics still contained carbonate groups after sintering at 1200 degrees C. Chemical analysis by X-ray fluorescence spectroscopy (XRF) and C-H-N analysis has shown that the cation/anion molar ratio (i.e. [Ca+Mg]/[P+C/2]) of the different compositions were 1.68(+/-0.01), which is equivalent to the Ca/P molar ratio of stoichiometric HA. Although the magnesium/carbonate co-substitution had a positive effect in preventing phase decomposition during sintering, it appeared to have a negative effect on the densification of the MgCO(3)-HA ceramics, compared to stoichiometric HA. PMID:15348578

  7. Microwave processing of ceramics

    SciTech Connect

    Katz, J.D.

    1989-01-01

    This paper discusses the following topics on microwave processing of ceramics: Microwave-material interactions; anticipated advantage of microwave sintering; ceramic sintering; and ceramic joining. 24 refs., 4 figs. (LSP)

  8. Chemical characterization of a potassium hydroxyapatite prepared by soaking in potassium chloride and carbonate solutions.

    PubMed

    Nordström, E G; Karlsson, K H

    1992-01-01

    A potassium-doped synthetic apatite was prepared by soaking hydroxyapatite in potassium carbonate and potassium chloride solutions. The hydroxyapatite was prepared by firing slip cast ceramic bodies in vacuum at 1100 degrees C. The conical ceramic samples and a crushed material of this were soaked in carbonate and chloride solutions for 2, 4, 6, and 8 weeks. Potassium, calcium, and phosphate were determined by direct current plasma emission spectroscopy. The carbonate content was determined by thermogravimetric analysis and chloride titrimetrically. After 2 weeks, one potassium ion substituted one calcium ion when soaked in a carbonate solution. When soaked in the chloride solution substitution occurred to the same extent. At phosphate sites the substitution of phosphate for carbonate occurred at one sixth of the sites after 2 weeks. Chloride incorporated one half of the OH-sites after 2 weeks. After 4 weeks about one chloride ion was found in the apatite, and after 6 weeks one and a half of the OH-sites were occupied by chloride ions. PMID:1483120

  9. Pulsed laser deposition of hydroxyapatite on titanium substrate with titania interlayer.

    PubMed

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

    2011-03-01

    Pulsed laser deposition (PLD) has been used to deposit hydroxyapatite (HA) ceramic over titanium substrate with an interlayer of titania. PLD has been identified as a potential candidate for bioceramic coatings over metallic substrates to be used as orthopedic and dental implants because of better process control and preservation of phase identity of the coating component. However, direct deposition of hydroxyapatite on titanium at elevated temperature results in the formation of natural oxide layer along with some perovskites like calcium titanate at the interface. This leads to easy debonding of ceramic layer from the metal and thereby affecting the adhesion strength. In the present study, adherent and stable HA coating over Ti6Al4V was achieved with the help of an interlayer of titania. The interlayer was made to a submicron level and HA was deposited consecutively to a thickness of around one micron by exposing to laser ablation at a substrate temperature of 400°C. The deposited phase was identified to be phase pure HA by X-ray diffraction, scanning electron microscopy, energy dispersive X-ray analysis, and inductively coupled plasma spectrometry. The mechanical behavior of coating evaluated by scratch test indicates that the adhesion strength of HA coating was improved with the presence of titania interlayer. PMID:21234791

  10. Formation of a sodium bicarbonate cluster in the structure of sodium-substituted hydroxyapatite

    NASA Astrophysics Data System (ADS)

    Tkachenko, M. V.; Kamzin, A. S.

    2015-02-01

    Ceramic sodium-substituted carbonated hydroxyapatite has been synthesized using the method of the solid-phase reaction in the temperature range of 640-820°C in water vapor. It has been established that substitutions of Ca2+ ions in the cation and anion subsystems with Na+ ions and the PO{4/3-} and OH- groups with CO{3/2-} ions lead to a considerable acceleration of the shrinkage and synthesis of dense ceramics at substantially lower temperatures than in the case of unsubstituted hydroxyapatite. Sintering in water vapor leads to densification of carbonate groups in channel positions, which induces the appearance of orderings of A2 and B2 types (bands with wave numbers 867 and 865 cm-1 in IR spectra, respectively) as well as the protonation of carbonate groups both in A and B sites and the formation of sodium bicarbonate clusters (856 and 859 cm-1) in addition to carbonate ordering of A1 and B1 types (879 and 872 cm-1).

  11. Characterisation of Suspension Precipitated Nanocrystalline Hydroxyapatite Powders

    NASA Astrophysics Data System (ADS)

    Mallik, P. K.; Swain, P. K.; Patnaik, S. C.

    2016-02-01

    Hydroxyapatite (HA) is a well-known biomaterial for coating on femoral implants, filling of dental cavity and scaffold for tissue replacement. Hydroxyapatite possess limited load bearing capacity due to their brittleness. In this paper, the synthesis of nanocrystalline hydroxyapatite powders was prepared by dissolving calcium oxide in phosphoric acid, followed by addition of ammonia liquor in a beaker. The prepared solution was stirred by using magnetic stirrer operated at temperature of 80°C for an hour. This leads to the formation of hydroxyapatite precipitate. The precipitate was dried in oven for overnight at 100°C. The dried agglomerated precipitate was calcined at 800°C in conventional furnace for an hour. The influence of calcium oxide concentration and pH on the resulting precipitates was studied using BET, XRD and SEM. As result, a well-defined sub-rounded morphology of powders size of ∼41 nm was obtained with a salt concentration of 0.02 M. Finally, it can be concluded that small changes in the reaction conditions led to large changes in final size, shape and degree of aggregation of the hydroxyapatite particles.

  12. Growth of hydroxyapatite nanoparticles on silica gels.

    PubMed

    Rivera-Muñoz, E M; Huirache-Acuña, R; Velázquez, R; Alonso-Núñez, G; Eguía-Eguía, S

    2011-06-01

    Synthetic, hydroxyapatite nanoparticles were grown on the surface of silica gels. The synthesis of those nanoparticles was obtained by immersing silica gels in a simulated body fluid (SBF) at 37 degrees C. The SBF was replaced every week to keep constant the Ca and P ion concentration and subsequent growth of hydroxyapatite was evaluated after 1-6 weeks of total soaking time in SBF. Hydroxyapatite nanoparticles were observed by scanning electron microscopy (SEM) on the surface of silica gel samples and confirmed by energy dispersive X-ray spectroscopy (EDS), Fourier Transform Infra Red Spectroscopy (FTIR) and powder X-ray Diffractometry (XRD) analysis. These particles show a regular shape and uniform size every week, keeping within the nanoscale always. Both the size and morphology of hydroxyapatite nanoparticles obtained are the result of the use of different chemical additives in the synthesis of silica gels, since they affect the liquid-to-solid interface, and the growth could correspond to a diffusion limited aggregation (DLA) process. A more detailed analysis, with higher magnifications, showed that hydroxyapatite nanoparticles are not solid spheres, showing a branched texture and their size depends on the scale and resolution of the measure instrument. PMID:21770224

  13. Investigating the addition of SiO₂-CaO-ZnO-Na₂O-TiO₂ bioactive glass to hydroxyapatite: Characterization, mechanical properties and bioactivity.

    PubMed

    Yatongchai, Chokchai; Placek, Lana M; Curran, Declan J; Towler, Mark R; Wren, Anthony W

    2015-11-01

    Hydroxyapatite (Ca10(PO4)6(OH)2) is widely investigated as an implantable material for hard tissue restoration due to its osteoconductive properties. However, hydroxyapatite in bulk form is limited as its mechanical properties are insufficient for load-bearing orthopedic applications. Attempts have been made to improve the mechanical properties of hydroxyapatite, by incorporating ceramic fillers, but the resultant composite materials require high sintering temperatures to facilitate densification, leading to the decomposition of hydroxyapatite into tricalcium phosphate, tetra-calcium phosphate and CaO phases. One method of improving the properties of hydroxyapatite is to incorporate bioactive glass particles as a second phase. These typically have lower softening points which could possibly facilitate sintering at lower temperatures. In this work, a bioactive glass (SiO2-CaO-ZnO-Na2O-TiO2) is incorporated (10, 20 and 30 wt%) into hydroxyapatite as a reinforcing phase. X-ray diffraction confirmed that no additional phases (other than hydroxyapatite) were formed at a sintering temperature of 560 ℃ with up to 30 wt% glass addition. The addition of the glass phase increased the % crystallinity and the relative density of the composites. The biaxial flexural strength increased to 36 MPa with glass addition, and there was no significant change in hardness as a function of maturation. The pH of the incubation media increased to pH 10 or 11 through glass addition, and ion release profiles determined that Si, Na and P were released from the composites. Calcium phosphate precipitation was encouraged in simulated body fluid with the incorporation of the bioactive glass phase, and cell culture testing in MC-3T3 osteoblasts determined that the composite materials did not significantly reduce cell viability. PMID:26116020

  14. PREFACE: Symposium 13: Ceramics for Medicine, Biotechnology and Biomimetics

    NASA Astrophysics Data System (ADS)

    Ohtsuki, Chikara

    2011-10-01

    Preface to Symposium 13 (Ceramics for Medicine, Biotechnology and Biomimetics) of the International Congress on Ceramics III, 14-18 November 2010, Osaka, Japan Ceramic materials are now widely used in biomedical fields, such as applications of artificial bones, joints and teeth. The high potential of ceramics to exhibit biological functionality is expected to produce novel materials supporting biotechnology. These applications are governed by the interactions of materials and biological molecules. So far, 'bioceramics' is a type of biomaterial used for repairing damaged tissues. The orthopaedic application of bioceramics has advanced rapidly since the invention of Bioglass® that was found to encourage direct bonding with living bone. Hydroxyapatite and calcium phosphate ceramics are now popular bioceramics for use in artificial bones. While the bone-bonding behavior of materials was understood phenomenologically, very little has been known about the mechanism of either hard or soft tissue attachment or tissue growth on ceramic-based materials, such as glasses, glass-ceramics, ceramic composites and organic-inorganic hybrids. This symposium discussed the scientific understanding of the interface between biomedical materials and soft/hard tissues, and the design and construction of nanoscopic interfaces. It also involved establishment of biomimetic structures, characterization of natural life-related hard and soft tissues, and their formation mechanisms for a wide range of applications in biotechnology through 45 oral presentations including 5 invited lectures and 45 posters. I wish to express my sincere appreciation to the organizers of this symposium in the ICC3 conference. I am also grateful to the invited speakers, all the participants and organizing committee of the ICC3. It is my great pleasure that this proceedings could be published as the fruit of this symposium's achievement, which includes the contributions in all aspect of scientific understanding and

  15. Ceramic stove

    SciTech Connect

    Goetz, M.

    1984-12-24

    A ceramic stove that may be supplied in kit form includes a base frame, a cast iron firebox secured on the base frame, a top frame attached to and surrounding the top of the firebox, and ceramic panels extending between and held by the frames in spaced relation from the firebox. The ceramic panels are ''ship-lapped'' relative to each other and are not cemented or otherwise positively attached to each other. Logs may be fed as fuel into the fire box door from one side of the stove allowing longer logs to be burned. The logs rest on a grate which includes a ''shakable'' portion for shaking ashes onto an ash pan located below the grate. A separate, small door into the firebox is provided for starting the fire and that door is covered by another, safety door which also closes the scape through whic the ash pan is removed for emptying. An outer screen gate is provided to overlie the firebox doors and the entire side of the firebos. Products of combustion rise in the firebox and are guided by a baffle in a desired serpentine path prolonging their containment, until they reach an outlet at the top of the fire box where they are then carried downwardly by a flue formed in part by a portion of the back wall of the firebox. A heat shield covers the back wall of the firebox including the flue whose outlet extends through the heat shield at mid elevation. Other features and advantages are also disclosed.

  16. Bioactive Surface Modification of Hydroxyapatite

    PubMed Central

    Okazaki, Yohei; Hiasa, Kyou; Yasuda, Keisuke; Nogami, Keisuke; Mizumachi, Wataru; Hirata, Isao

    2013-01-01

    The purpose of this study was to establish an acid-etching procedure for altering the Ca/P ratio of the nanostructured surface of hydroxyapatite (HAP) by using surface chemical and morphological analyses (XPS, XRD, SEM, surface roughness, and wettability) and to evaluate the in vitro response of osteoblast-like cells (MC3T3-E1 cells) to the modified surfaces. This study utilized HAP and HAP treated with 10%, 20%, 30%, 40%, 50%, or 60% phosphoric acid solution for 10 minutes at 25°C, followed by rinsing 3 times with ultrapure water. The 30% phosphoric acid etching process that provided a Ca/P ratio of 1.50, without destruction of the grain boundary of HAP, was selected as a surface-modification procedure. Additionally, HAP treated by the 30% phosphoric acid etching process was stored under dry conditions at 25°C for 12 hours, and the Ca/P ratio approximated to 1.00 accidentally. The initial adhesion, proliferation, and differentiation (alkaline phosphatase (ALP) activity and relative mRNA level for ALP) of MC3T3-E1 cells on the modified surfaces were significantly promoted (P < 0.05 and 0.01). These findings show that the 30% phosphoric acid etching process for the nanostructured HAP surface can alter the Ca/P ratio effectively and may accelerate the initial adhesion, proliferation, and differentiation of MC3T3-E1 cells. PMID:23862150

  17. Monolithic ceramics

    NASA Technical Reports Server (NTRS)

    Herbell, Thomas P.; Sanders, William A.

    1992-01-01

    A development history and current development status evaluation are presented for SiC and Si3N4 monolithic ceramics. In the absence of widely sought improvements in these materials' toughness, and associated reliability in structural applications, uses will remain restricted to components in noncritical, nonman-rated aerospace applications such as cruise missile and drone gas turbine engine components. In such high temperature engine-section components, projected costs lie below those associated with superalloy-based short-life/expendable engines. Advancements are required in processing technology for the sake of fewer and smaller microstructural flaws.

  18. Finite Element Simulation of Diametral Strength Test of Hydroxyapatite

    SciTech Connect

    Ozturk, Fahrettin; Toros, Serkan; Evis, Zafer

    2011-01-17

    In this study, the diametral strength test of sintered hydroxyapatite was simulated by the finite element software, ABAQUS/Standard. Stress distributions on diametral test sample were determined. The effect of sintering temperature on stress distribution of hydroxyapatite was studied. It was concluded that high sintering temperatures did not reduce the stress on hydroxyapatite. It had a negative effect on stress distribution of hydroxyapatite after 1300 deg. C. In addition to the porosity, other factors (sintering temperature, presence of phases and the degree of crystallinity) affect the diametral strength of the hydroxyapatite.

  19. Bonding behavior between two bioactive ceramics in vivo.

    PubMed

    Kitsugi, T; Yamamuro, T; Nakamura, T; Kokubo, T; Takagi, M; Shibuya, T; Takeuchi, H; Ono, M

    1987-09-01

    The purpose of this study is to examine the chemical bonding mechanism between bioactive ceramics in vivo. Two experiments were performed. In the first experiment, rectangular specimens (5 mm X 5 mm X 25 mm) of apatite-wollastonite containing glass-ceramics (designated A.W-GC) were used. In the second experiment, plates (15 mm X 10 mm X 2 mm) of A.W-GC and three types of hydroxyapatite (designated HA) were used. The sintering temperature and porosity (%) of the three types of HA were 1200 degrees C (0.4%), 1000 degrees C (4.8%), and 800 degrees C (45%), respectively. In each experiment, two pairs of specimens of identical material, one bound with silk thread, the other not bound, were implanted subcutaneously into rats. In the first experiment, bonding of only bound specimens was observed at 3 and 6 months after implantation. The observation of interface by SEM-EPMA showed that a Ca-P-rich layer formed between the two specimens. In the second experiment, bonding of both bound and nonbound A.W-GC produced identical results 1 month after implantation. For HA sintered at 800 degrees C and 1000 degrees C, bonding was observed in every specimen. This phenomenon might be caused by the chemical change of hydroxyapatite occurring at different sintering temperatures. The Ca-P-rich layer was observed between two plates. These results suggest that self-repair of bioactive ceramic is possible under certain conditions. PMID:3667637

  20. Biomedical nanocomposites of hydroxyapatite/polycaprolactone obtained by surfactant mediation.

    PubMed

    Kim, Hae-Won

    2007-10-01

    The composite approach to combining bioactive ceramic and degradable polymer is a promising strategy in the development of bone regenerative matrices. Moreover, in the fabrication of composites, the nanoscale organization of each component should improve the level of structural integration as well as the resultant mechanical and biological properties. The aim of this study was to develop a novel nanocomposite system consisting of hydroxyapatite (HA) and poly(epsilon-caprolactone) (PCL), wherein the HA nanoparticles were uniformly dispersed within the PCL matrix. The strategy was based on applying an amphiphilic surfactant, oleic acid in this case, between the HA and PCL. Oleic acid, which belongs to the fatty acid family and is generally noncytotoxic at the levels used in this study, is believed to mediate the interaction between the hydrophilic HA and hydrophobic PCL. With the mediation of oleic acid, the HA nanoparticles were distributed uniformly within the PCL matrix on the nanoscale (distributed particle size of less than 1 microm), which is in marked contrast to the conventionally mixed HA-PCL composite, in which the HA particles were severely agglomerated. The developed nanocomposite had significantly higher mechanical strength than did the conventional composite and the pure PCL. Moreover, the osteoblastic cells showed a better proliferation behavior on the nanocomposite than on the conventional composite. This HA-PCL nanocomposite mediated by oleic acid is expected to be useful in the bone regeneration field. Moreover, this methodology is applicable to the nanocomposite processing of other biomedical materials. PMID:17390319

  1. Synthesis and characterisation of copper doped Ca-Li hydroxyapatite

    NASA Astrophysics Data System (ADS)

    Pogosova, M. A.; Kazin, P. E.; Tretyakov, Y. D.

    2012-08-01

    Hydroxyapapites M10(PO4)6(OH)2 (MHAP), where M is an alkaline earth metal, colored by incorporation of copper ions substituting protons, were discovered recently [1]. Now this kind of apatite-type materials can be used as inorganic pigments. Until now blue (BaHAP), violet (SrHAP) and wine-red (CaHAP) colors were achieved by the copper ions introduction [2]. The task of the present work was to study possibility of further M-ion substitution to affect the color and shift it toward the red-orange tint. Polycrystalline hydroxyapatites Ca10-xLix+yCuz(PO4)6O2H2-y-z-σ (Ca-LiHAP) were synthesized by solid state reaction at 1150 °C (ceramic method) and studied by X-ray powder diffraction (XRD), infrared absorption and diffuse-reflectance spectroscopy. Refinement of the X-ray diffraction patterns by the Rietveld method shows that CaHAP unit cell parameters are a little bigger, than Ca-LiHAP ones. Small difference between unit cell parameters could be caused by two ways of the Li+ ions introduction: (1) at the Ca2+ sites (Ca-Li substitution); (2) into hexagonal channels (H-Li substitution). The Li ions doping changes the color of the copper doped CaHAP from wine-red to pink and red.

  2. Development and Characterization of Biphasic Hydroxyapatite/β-TCP Cements

    PubMed Central

    Gallinetti, Sara; Canal, Cristina; Ginebra, Maria-Pau; Ferreira, J

    2014-01-01

    Biphasic calcium phosphate bioceramics composed of hydroxyapatite (HA) and β-tricalcium phosphate (β-TCP) have relevant properties as synthetic bone grafts, such as tunable resorption, bioactivity, and intrinsic osteoinduction. However, they have some limitations associated to their condition of high-temperature ceramics. In this work self-setting Biphasic Calcium Phosphate Cements (BCPCs) with different HA/β-TCP ratios were obtained from self-setting α-TCP/β-TCP pastes. The strategy used allowed synthesizing BCPCs with modulated composition, compressive strength, and specific surface area. Due to its higher solubility, α-TCP was fully hydrolyzed to a calcium-deficient HA (CDHA), whereas β-TCP remained unreacted and completely embedded in the CDHA matrix. Increasing amounts of the non-reacting β-TCP phase resulted in a linear decrease of the compressive strength, in association to the decreasing amount of precipitated HA crystals, which are responsible for the mechanical consolidation of apatitic cements. Ca2+ release and degradation in acidic medium was similar in all the BCPCs within the timeframe studied, although differences might be expected in longer term studies once β-TCP, the more soluble phase was exposed to the surrounding media. PMID:25866411

  3. Ceramic fiber ceramic matrix filter development

    SciTech Connect

    Judkins, R.R.; Stinton, D.P.; Smith, R.G.; Fischer, E.M.

    1994-09-01

    The objectives of this project were to develop a novel type of candle filter based on a ceramic fiber-ceramic matrix composite material, and to extend the development to full-size, 60-mm OD by 1-meter-long candle filters. The goal is to develop a ceramic filter suitable for use in a variety of fossil energy system environments such as integrated coal gasification combined cycles (IGCC), pressurized fluidized-bed combustion (PFBC), and other advanced coal combustion environments. Further, the ceramic fiber ceramic matrix composite filter, hereinafter referred to as the ceramic composite filter, was to be inherently crack resistant, a property not found in conventional monolithic ceramic candle filters, such as those fabricated from clay-bonded silicon carbide. Finally, the adequacy of the filters in the fossil energy system environments is to be proven through simulated and in-plant tests.

  4. Environmental durability of ceramics and ceramic composites

    NASA Technical Reports Server (NTRS)

    Fox, Dennis S.

    1992-01-01

    An account is given of the current understanding of the environmental durability of both monolithic ceramics and ceramic-matrix composites, with a view to the prospective development of methods for the characterization, prediction, and improvement of ceramics' environmental durability. Attention is given to the environmental degradation behaviors of SiC, Si3N4, Al2O3, and glass-ceramic matrix compositions. The focus of corrosion prevention in Si-based ceramics such as SiC and Si3N4 is on the high and low sulfur fuel combustion-product effects encountered in heat engine applications of these ceramics; sintering additives and raw material impurities are noted to play a decisive role in ceramics' high temperature environmental response.

  5. Preparation of irregular mesoporous hydroxyapatite

    SciTech Connect

    Wang Hualin Zhai Linfeng; Li Yanhong; Shi Tiejun

    2008-06-03

    An irregular mesoporous hydroxyapatite (meso-HA), Ca{sub 10}(PO{sub 4}){sub 6}(OH){sub 2}, is successfully prepared from Ca(NO{sub 3}){sub 2}.4H{sub 2}O and NH{sub 4}H{sub 2}PO{sub 4} using surfactant cetyltrimethyl ammonium bromide (CTAB) as template. Fourier transform infrared spectroscopy (FTIR) and differential scanning calorimetry (DSC) results reveal that the positive head of CTAB is assembled on the surface precipitated HA and much NH{sub 4}{sup +} is enclosed in precipitated HA before calcination. Field scanning electron microscope (FSEM) reveals that there exist many interconnected pores throughout the HA reticular skeleton. Nitrogen adsorption-desorption experiment exhibits a mesoporous material type IV curve, and pore size distribution calculated from the desorption branch of the isotherms based on Barrett-Joyner-Halenda (BJH) model shows that most pores throughout the HA reticular skeleton are sized at about 40 nm, but the pores are not uniform on the whole, owning to decomposition of the 'organic' CTAB templating structures and ammonium salt enclosed in the precipitated HA. The specific surface area of irregular meso-HA is calculated to be 37.6 m{sup 2}/g according to the Brunauer-Emmett-Teller (BET) equation. Moreover, after polylactic acid/meso-HA (PLA/meso-HA) composites degraded 12 weeks in normal saline at 37 deg. C, the interconnected pores throughout the HA skeleton were enlarged and sized in micron degree, which resemble trabecular bone structure very much.

  6. Development of hydroxyapatite/calcium silicate composites addressed to the design of load-bearing bone scaffolds.

    PubMed

    Sprio, Simone; Tampieri, Anna; Celotti, Giancarlo; Landi, Elena

    2009-04-01

    This work deals with the preparation of bioactive ceramic composites to be employed for the development of load-bearing bone substitutes, made of hydroxyapatite (Ca(10)(PO(4))(6)(OH)(2), HA) and bioactive dicalcium silicate (Ca(2)SiO(4), C(2)S) as a reinforcing phase. The composite materials were prepared by Fast Hot-Pressing (FHP), which allowed the rapid sintering of monolithic ceramics at temperatures up to 1500 degrees C, well above the commonly adopted temperatures for the consolidation of hydroxyapatite (1200-1300 degrees C). The purpose was to achieve the grain coalescence of both HA and the strengthening phase, so that to obtain a homogeneous ceramic material characterized by controlled phase composition and improved mechanical strength; the dwell time was reduced as much as possible to prevent HA decomposition and excessive grain growth. The most remarkable result, in terms of phase composition, was the absence of any secondary phases in the final ceramics other than HA and C(2)S, even after sintering at 1500 degrees C. The flexure strength of the composite materials was found to be much higher than that of HA alone. Further mechanical characterization was also carried out on HA and composites, sintered in different conditions, to evaluate the elastic properties and fracture toughness, and properties close to those of mineral bone were found. These preliminary results confirmed that composites of HA and Ca(2)SiO(4) are promising for the development of bioactive load-bearing ceramic bone substitutes with controlled phase composition. PMID:19627818

  7. Thickness of hydroxyapatite nanocrystal controls mechanical properties of the collagen-hydroxyapatite interface.

    PubMed

    Qin, Zhao; Gautieri, Alfonso; Nair, Arun K; Inbar, Hadass; Buehler, Markus J

    2012-01-31

    Collagen-hydroxyapatite interfaces compose an important building block of bone structures. While it is known that the nanoscale structure of this elementary building block can affect the mechanical properties of bone, a systematic understanding of the effect of the geometry on the mechanical properties of this interface between protein and mineral is lacking. Here we study the effect of geometry, different crystal surfaces, and hydration on the mechanical properties of collagen-hydroxyapatite interfaces from an atomistic perspective, and discuss underlying deformation mechanisms. We find that the presence of hydroxyapatite significantly enhances the tensile modulus and strength compared with a tropocollagen molecule alone. The stiffening effect is strongly dependent on the thickness of the mineral crystal until a plateau is reached at 2 nm crystal thickness. We observe no significant differences due to the mineral surface (Ca surface vs OH surface) or due to the presence of water. Our result shows that the hydroxyapatite crystal with its thickness confined to the nanometer size efficiently increases the tensile modulus and strength of the collagen-hydroxyapatite composite, agreeing well with experimental observations that consistently show the existence of extremely thin mineral flakes in various types of bones. We also show that the collagen-hydroxyapatite interface can be modeled with an elastic network model which, based on the results of atomistic simulations, provides a good estimate of the surface energy and other mechanical features. PMID:22208454

  8. [Adsorption of Congo red from aqueous solution on hydroxyapatite].

    PubMed

    Zhan, Yan-Hui; Lin, Jian-Wei

    2013-08-01

    The adsorption of Congo red (CR) from aqueous solution on hydroxyapatite was investigated using batch experiments. The hydroxyapatite was effective for CR removal from aqueous solution. The adsorption kinetics of CR on hydroxyapatite well followed a pseudo-second-order model. The equilibrium adsorption data of CR on hydroxyapatite could be described by the Langmuir, Freundlich and Dubinin-Radushkevich (D-R) isotherm models. Thermodynamic parameters such as Gibbs free energy change, enthalpy change and entropy change were calculated and showed that the adsorption of CR on hydroxyapatite was spontaneous and exothermic in nature. The CR adsorption capacity for hydroxyapatite decreased significantly with increasing pH from 8 to 10. Thermal regeneration showed that hydroxyapatite could be used for six desorption-adsorption cycles with high removal efficiency for CR in each cycle. The mechanisms for CR adsorption on hydroxyapatite with pH value below the pH at point of zero charge (pH(PZC)) include electrostatic attraction, hydrogen bonding and Lewis acid-base interaction. The mechanisms for CR adsorption on hydroxyapatite with pH value above its pH(PZC) include hydrogen bonding and Lewis acid-base interaction. Results of this work indicate that hydroxyapatite is a promising adsorbent for CR removal from aqueous solution. PMID:24191561

  9. Nutrient-substituted hydroxyapatites: synthesis and characterization

    NASA Technical Reports Server (NTRS)

    Golden, D. C.; Ming, D. W.

    1999-01-01

    Incorporation of Mg, S, and plant-essential micronutrients into the structure of synthetic hydroxyapatite (HA) may be advantageous for closed-loop systems, such as will be required on Lunar and Martian outposts, because these apatites can be used as slow-release fertilizers. Our objective was to synthesize HA with Ca, P, Mg, S, Fe, Cu, Mn, Zn, Mo, B, and Cl incorporated into the structure, i.e., nutrient-substituted apatites. Hydroxyapatite, carbonate hydroxyapatite (CHA), nutrient-substituted hydroxyapatite (NHA), and nutrient-substituted carbonate hydroxyapatite (NCHA) were synthesized by precipitating from solution. Chemical and mineralogical analysis of precipitated samples indicated a considerable fraction of the added cations were incorporated into HA, without mineral impurities. Particle size of the HA was in the 1 to 40 nm range, and decreased with increased substitution of nutrient elements. The particle shape of HA was elongated in the c-direction in unsubstituted HA and NHA but more spherical in CHA and NCHA. The substitution of cations and anions in the HA structure was confirmed by the decrease of the d[002] spacing of HA with substitution of ions with an ionic radius less than that of Ca or P. The DTPA-extractable Cu ranged from 8 to 8429 mg kg-1, Zn ranged from 57 to 1279 mg kg-1, Fe from 211 to 2573 mg kg-1, and Mn from 190 to 1719 mg kg-1, depending on the substitution level of each element in HA. Nutrient-substituted HA has the potential to be used as a slow-release fertilizer to supply micronutrients, S, and Mg in addition to Ca and P.

  10. Superplastic ceramics and intermetallics and their potential applications

    SciTech Connect

    Wadsworth, J.; Nieh, T.G.

    1994-11-01

    Recent advances in the basic understanding of superplasticity and superplastic forming of ceramics and intermetallics are reviewed. Fine-grained superplastic ceramics, including yttria-stabilized tetragonal zirconia polycrystal, Y- or MgO-doped Al{sub 2}O{sub 3} Hydroxyapatite, {beta}-spodumene glass ceramics, Al{sub 2}0{sub 3}-YTZP two-phase composites, SiC-Si{sub 3}N{sub 4} and Fe-Fe{sub 3}C composites, are discussed. Superplasticity in the nickel-base (e.g., Ni{sub 3}Al and Ni{sub 3}Si) and titanium-base intermetallics (TiAl and T1{sub 3}Al), is described. Deformation mechanisms as well as microstructural requirements and effects such as grain size, grain growth, and grain-boundary phases, on the superplastic deformation behavior am addressed. Factors that control the superplastic tensile elongation of ceramics are discussed. Superplastic forming, and particularly biaxial gas-pressure forming, of several ceramics and intermetallics are presented with comments on the likelihood of commercial application.

  11. Dental ceramics: An update

    PubMed Central

    Shenoy, Arvind; Shenoy, Nina

    2010-01-01

    In the last few decades, there have been tremendous advances in the mechanical properties and methods of fabrication of ceramic materials. While porcelain-based materials are still a major component of the market, there have been moves to replace metal ceramics systems with all ceramic systems. Advances in bonding techniques have increased the range and scope for use of ceramics in dentistry. In this brief review, we will discuss advances in ceramic materials and fabrication techniques. Examples of the microstructure property relationships for these ceramic materials will also be addressed. PMID:21217946

  12. Ceramic inspection system

    DOEpatents

    Werve, Michael E.

    2006-05-16

    A system for inspecting a ceramic component. The ceramic component is positioned on a first rotary table. The first rotary table rotates the ceramic component. Light is directed toward the first rotary table and the rotating ceramic component. A detector is located on a second rotary table. The second rotary table is operably connected to the first rotary table and the rotating ceramic component. The second rotary table is used to move the detector at an angle to the first rotary table and the rotating ceramic component.

  13. Irradiation conditions for fiber laser bonding of HAp-glass ceramics with bovine cortical bone.

    PubMed

    Tadano, Shigeru; Yamada, Satoshi; Kanaoka, Masaru

    2014-01-01

    Orthopedic implants are widely used to repair bones and to replace articulating joint surfaces. It is important to develop an instantaneous technique for the direct bonding of bone and implant materials. The aim of this study was to develop a technique for the laser bonding of bone with an implant material like ceramics. Ceramic specimens (10 mm diameter and 1 mm thickness) were sintered with hydroxyapatite and MgO-Al2O3-SiO2 glass powders mixed in 40:60 wt% proportions. A small hole was bored at the center of a ceramic specimen. The ceramic specimen was positioned onto a bovine bone specimen and a 5 mm diameter area of the ceramic specimen was irradiated using a fiber laser beam (1070-1080 nm wavelength). As a result, the bone and the ceramic specimens bonded strongly under the irradiation conditions of a 400 W laser power and a 1.0 s exposure time. The maximum shear strength was 5.3 ± 2.3 N. A bonding substance that penetrated deeply into the bone specimen was generated around the hole in the ceramic specimen. On using the fiber laser, the ceramic specimen instantaneously bonded to the bone specimen. Further, the irradiation conditions required for the bonding were investigated. PMID:24840194

  14. Ferroelectric polarization in nanocrystalline hydroxyapatite thin films on silicon.

    PubMed

    Lang, S B; Tofail, S A M; Kholkin, A L; Wojtaś, M; Gregor, M; Gandhi, A A; Wang, Y; Bauer, S; Krause, M; Plecenik, A

    2013-01-01

    Hydroxyapatite nanocrystals in natural form are a major component of bone--a known piezoelectric material. Synthetic hydroxyapatite is widely used in bone grafts and prosthetic pyroelectric coatings as it binds strongly with natural bone. Nanocrystalline synthetic hydroxyapatite films have recently been found to exhibit strong piezoelectricity and pyroelectricity. While a spontaneous polarization in hydroxyapatite has been predicted since 2005, the reversibility of this polarization (i.e. ferroelectricity) requires experimental evidence. Here we use piezoresponse force microscopy to demonstrate that nanocrystalline hydroxyapatite indeed exhibits ferroelectricity: a reversal of polarization under an electrical field. This finding will strengthen investigations on the role of electrical polarization in biomineralization and bone-density related diseases. As hydroxyapatite is one of the most common biocompatible materials, our findings will also stimulate systematic exploration of lead and rare-metal free ferroelectric devices for potential applications in areas as diverse as in vivo and ex vivo energy harvesting, biosensing and electronics. PMID:23884324

  15. Synthesis of Si, Mg substituted hydroxyapatites and their sintering behaviors.

    PubMed

    Kim, S R; Lee, J H; Kim, Y T; Riu, D H; Jung, S J; Lee, Y J; Chung, S C; Kim, Y H

    2003-04-01

    Si, Mg-substituted hydroxyapatites, alone and co-substituted, have been prepared to obtain biomaterials having an improved biocompatibility. From FT-IR, XRD and ICP analyses, it was confirmed that single phases of hydroxyapatite substituted by Si alone or co-substituted by Si, Mg. The XRD data indicated the absence of extra phases related to silicon and magnesium oxide or other calcium phosphate species. Si-substituted hydroxyapatite of up to 2 wt% for Si and Si, Mg co-substituted hydroxyapatite of 1 wt% for the each ion keep their original structures intact for the sintering temperatures of up to 1200 degrees C. However, it is observed that ion substitutions by an amount higher than the above ratios for each hydroxyapatite lead to destabilization of original structures of the hydroxyapatite and to the production of tricalcium phosphate and calcium phosphate silicate phases when the samples were sintered at 1100 degrees C or higher. PMID:12527280

  16. Ferroelectric Polarization in Nanocrystalline Hydroxyapatite Thin Films on Silicon

    NASA Astrophysics Data System (ADS)

    Lang, S. B.; Tofail, S. A. M.; Kholkin, A. L.; Wojtaś, M.; Gregor, M.; Gandhi, A. A.; Wang, Y.; Bauer, S.; Krause, M.; Plecenik, A.

    2013-07-01

    Hydroxyapatite nanocrystals in natural form are a major component of bone- a known piezoelectric material. Synthetic hydroxyapatite is widely used in bone grafts and prosthetic pyroelectric coatings as it binds strongly with natural bone. Nanocrystalline synthetic hydroxyapatite films have recently been found to exhibit strong piezoelectricity and pyroelectricity. While a spontaneous polarization in hydroxyapatite has been predicted since 2005, the reversibility of this polarization (i.e. ferroelectricity) requires experimental evidence. Here we use piezoresponse force microscopy to demonstrate that nanocrystalline hydroxyapatite indeed exhibits ferroelectricity: a reversal of polarization under an electrical field. This finding will strengthen investigations on the role of electrical polarization in biomineralization and bone-density related diseases. As hydroxyapatite is one of the most common biocompatible materials, our findings will also stimulate systematic exploration of lead and rare-metal free ferroelectric devices for potential applications in areas as diverse as in vivo and ex vivo energy harvesting, biosensing and electronics.

  17. Ferroelectric Polarization in Nanocrystalline Hydroxyapatite Thin Films on Silicon

    PubMed Central

    Lang, S. B.; Tofail, S. A. M.; Kholkin, A. L.; Wojtaś, M.; Gregor, M.; Gandhi, A. A.; Wang, Y.; Bauer, S.; Krause, M.; Plecenik, A.

    2013-01-01

    Hydroxyapatite nanocrystals in natural form are a major component of bone- a known piezoelectric material. Synthetic hydroxyapatite is widely used in bone grafts and prosthetic pyroelectric coatings as it binds strongly with natural bone. Nanocrystalline synthetic hydroxyapatite films have recently been found to exhibit strong piezoelectricity and pyroelectricity. While a spontaneous polarization in hydroxyapatite has been predicted since 2005, the reversibility of this polarization (i.e. ferroelectricity) requires experimental evidence. Here we use piezoresponse force microscopy to demonstrate that nanocrystalline hydroxyapatite indeed exhibits ferroelectricity: a reversal of polarization under an electrical field. This finding will strengthen investigations on the role of electrical polarization in biomineralization and bone-density related diseases. As hydroxyapatite is one of the most common biocompatible materials, our findings will also stimulate systematic exploration of lead and rare-metal free ferroelectric devices for potential applications in areas as diverse as in vivo and ex vivo energy harvesting, biosensing and electronics. PMID:23884324

  18. Simple route for nano-hydroxyapatite properties expansion.

    PubMed

    Rojas, L; Olmedo, H; García-Piñeres, A J; Silveira, C; Tasic, L; Fraga, F; Montero, M L

    2015-09-01

    Simple surface modification of nano-hydroxyapatite, through acid-basic reactions, allows expanding the properties of this material. Introduction of organic groups such as hydrophobic alkyl chains, carboxylic acid, and amide or amine basic groups on the hydroxyapatite surface systematically change the polarity, surface area, and reactivity of hydroxyapatite without modifying its phase. Physical and chemical properties of the new derivative particles were analyzed. The biocompatibility of modified Nano-Hap on Raw 264.7 cells was also assessed. PMID:26481455

  19. Joining Ceramics By Brazing

    NASA Technical Reports Server (NTRS)

    Chiaramonte, Francis P.; Sudsina, Michael W.

    1992-01-01

    Certain ceramic materials tightly bond together by brazing with suitable alloys. Enables fabrication of parts of wide variety of shapes from smaller initial pieces of ceramics produced directly in only limited variety of shapes.

  20. Porous hydroxyapatite and gelatin/hydroxyapatite microspheres obtained by calcium phosphate cement emulsion.

    PubMed

    Perez, Roman A; Del Valle, Sergio; Altankov, George; Ginebra, Maria-Pau

    2011-04-01

    Hydroxyapatite and hybrid gelatine/hydroxyapatite microspheres were obtained through a water in oil emulsion of a calcium phosphate cement (CPC). The setting reaction of the CPC, in this case the hydrolysis of α-tricalcium phosphate, was responsible for the consolidation of the microspheres. After the setting reaction, the microspheres consisted of an entangled network of hydroxyapatite crystals, with a high porosity and pore sizes ranging between 0.5 and 5 μm. The size of the microspheres was tailored by controlling the viscosity of the hydrophobic phase, the rotation speed, and the initial powder size of the CPC. The incorporation of gelatin increased the sphericity of the microspheres, as well as their size and size dispersion. To assess the feasibility of using the microspheres as cell microcarriers, Saos-2 cells were cultured on the microspheres. Fluorescent staining, SEM studies, and LDH quantification showed that the microspheres were able to sustain cell growth. Cell adhesion and proliferation was significantly improved in the hybrid gelatin/hydroxyapatite microspheres as compared to the hydroxyapatite ones. PMID:21290594

  1. Mechanical properties and biocompatibility of the sputtered Ti doped hydroxyapatite.

    PubMed

    Vladescu, A; Padmanabhan, S C; Ak Azem, F; Braic, M; Titorencu, I; Birlik, I; Morris, M A; Braic, V

    2016-10-01

    The hydroxyapatite enriched with Ti were prepared as possible candidates for biomedical applications especially for implantable devices that are in direct contact to the bone. The hydroxyapatites with different Ti content were prepared by RF magnetron sputtering on Ti-6Al-4V alloy using pure hydroxyapatite and TiO2 targets. The content of Ti was modified by changing the RF power fed on TiO2 target. The XPS and FTIR analyses revealed the presence of hydroxyapatite structure. The hardness and elastic modulus of the hydroxyapatite were increased by Ti addition. After 5 days of culture, the cell viability of the Ti-6Al-4V was enhanced by depositing with undoped or doped hydroxyapatite. The Ti additions led to an increase in cell viability of hydroxyapatite, after 5 days of culture. The electron microscopy showed the presence of more cells on the surface of Ti-enriched hydroxyapatite than those observed on the surface of the uncoated alloys or undoped hydroxyapatite. PMID:27450034

  2. Morphology and electronic structure of nanoscale powders of calcium hydroxyapatite

    NASA Astrophysics Data System (ADS)

    Kurgan, Nataly; Karbivskyy, Volodymyr; Kasyanenko, Vasyl

    2015-02-01

    Atomic force microscopy, infrared spectroscopy and NMR studied morphological and physicochemical properties of calcium hydroxyapatite powders produced by changing the temperature parameters of synthesis. Features of morphology formation of calcium hydroxyapatite nanoparticles with an annealing temperature within 200°C to 1,100°C were determined. It is shown that the particle size of the apatite obtained that annealed 700°C is 40 nm corresponding to the particle size of apatite in native bone. The effect of dimension factor on structural parameters of calcium hydroxyapatite is manifested in a more local symmetry of the PO4 3- tetrahedra at nanodispersed calcium hydroxyapatite.

  3. Ceramic electrolyte coating methods

    DOEpatents

    Seabaugh, Matthew M.; Swartz, Scott L.; Dawson, William J.; McCormick, Buddy E.

    2004-10-12

    Processes for preparing aqueous suspensions of a nanoscale ceramic electrolyte material such as yttrium-stabilized zirconia. The invention also includes a process for preparing an aqueous coating slurry of a nanoscale ceramic electrolyte material. The invention further includes a process for depositing an aqueous spray coating slurry including a ceramic electrolyte material on pre-sintered, partially sintered, and unsintered ceramic substrates and products made by this process.

  4. Nanocrystalline spin coated sol-gel hydroxyapatite thin films on Ti substrate: Towards potential applications for implants

    NASA Astrophysics Data System (ADS)

    Carradò, Adele; Viart, Nathalie

    2010-07-01

    Sol-gel spin coating is a promising process to obtain hydroxyapatite (HA) thin films. It is an alternative route to the hydroxyapatite deposition techniques usually employed to cover orthopaedic or dental titanium implant surfaces. The sol-gel (SG) parameters leading to a pure and crystalline HA coatings on Ti substrate were determined. They allow to reach a stoichiometric hydroxyapatite composition (ideal Ca/P atomic ratio 1.67) and a control of the growth of the crystalline phases. The samples, when observed by Scanning Electron Microscopy (SEM), exhibit grains of ca. 200 nm, well adapted for cell proliferation. The crystallisation of the HA films was thoroughly studied by X-Ray diffraction (XRD). The aim of this paper is to validate the sol-gel method as a processing method allowing the control of the mechanical state of the films and, in particular, of the residual stresses (RS) at metal-ceramic interfaces. These stresses were determined on titanium substrates. While the uncoated Ti substrates were in a compressive residual state, the coated ones were in a low tensile state. These results suggest that the sol-gel process is indeed a processing route to obtain HA coated Ti implants.

  5. Brittleness of ceramics

    NASA Technical Reports Server (NTRS)

    Kroupa, F.

    1984-01-01

    The main characteristics of mechanical properties of ceramics are summarized and the causes of their brittleness, especially the limited mobility of dislocations, are discussed. The possibility of improving the fracture toughness of ceramics and the basic research needs relating to technology, structure and mechanical properties of ceramics are stressed in connection with their possible applications in engineering at high temperature.

  6. Ceramic to metal seal

    DOEpatents

    Snow, Gary S.; Wilcox, Paul D.

    1976-01-01

    Providing a high strength, hermetic ceramic to metal seal by essentially heating a wire-like metal gasket and a ceramic member, which have been chemically cleaned, while simultaneously deforming from about 50 to 95 percent the metal gasket against the ceramic member at a temperature of about 30 to 75 percent of the melting temperature of the metal gasket.

  7. Reactive hydroxyapatite fillers for pectin biocomposites.

    PubMed

    Munarin, Fabiola; Petrini, Paola; Barcellona, Giulia; Roversi, Tommaso; Piazza, Laura; Visai, Livia; Tanzi, Maria Cristina

    2014-12-01

    In this work, a novel injectable biocomposite hydrogel is produced by internal gelation, using pectin as organic matrix and hydroxyapatite either as crosslinking agent and inorganic reinforcement. Tunable gelling kinetics and rheological properties are obtained varying the hydrogels' composition, with the final aim of developing systems for cell immobilization. The reversibility by dissolution of pectin-hydroxyapatite hydrogels is achieved with saline solutions, to possibly accelerate the release of the cells or active agents immobilized. Texture analysis confirms the possibility of extruding the biocomposites from needles with diameters from 20 G to 30 G, indicating that they can be implanted with minimally-invasive approaches, minimizing the pain during injection and the side effects of the open surgery. L929 fibroblasts entrapped in the hydrogels survive to the immobilization procedure and exhibit high cell viability. On the overall, these systems result to be suitable supports for the immobilization of cells for tissue regeneration applications. PMID:25491814

  8. Biomineralization of nanoscale single crystal hydroxyapatite.

    PubMed

    Omokanwaye, Tiffany; Wilson, Otto C; Gugssa, Ayelle; Anderson, Winston

    2015-11-01

    The chemical and physical characteristics of nanocrystalline hydroxyapatite particles which formed during the subcutaneous implantation of crab shell in Sprague-Dawley rats were studied using selected area electron diffraction (SAED) and high resolution transmission electron microscopy (HRTEM). The initial SAED characterization evidence indicated the presence of an amorphous calcium phosphate phase. The electron dense nanophase particles which formed in the wound healing zone displayed broad diffuse rings which usually indicate a low crystalline order or amorphous phase. High resolution transmission electron microscopy (HRTEM) revealed that these mineralized regions contained discrete single crystal particles less than 5nm in size. Micrographs taken at successively higher magnifications revealed very small nanoparticles with a hexagonal arrangement of ion channels with characteristic spacing of 0.54nm and 0.23nm. This study revealed that single crystal hydroxyapatite nanoparticles consisting of only a few unit cells formed via a biomineralization directed process. PMID:26249568

  9. Mechanical properties of hydroxyapatite/mica composite.

    PubMed

    Nordström, E G; Herø, H; Jørgensen, R B

    1994-01-01

    Bend specimens of the inorganic synthetic materials hydroxyapatite (HA) and a composite of hydroxyapatite/muscovite mica have been prepared and tested mechanically. Sintering followed by hot isostatic pressing (HIP) without encapsulation gave an increased strength for HA alone, but no significant increase in strength compared with sintering alone for HA/mica composites. The bend strength of the HA/mica composite was inferior to that of HA alone, the reason being inadequate bonding between HA and mica. HIP in glass capsules and an increased cold compaction pressure tended to improve the bend strength of the composite. Corrosion in tris for 7 d did not affect the bend strength of the investigated materials significantly. PMID:7950878

  10. [Structural features of ectopic bone-like tissue in porous hydroxyapatite blocks].

    PubMed

    Hattori, Shigetaka

    2008-06-01

    Calcium phosphate ceramics are widely used as bone substitutes because of their favorable biocompatibility and osteoconductivity. Some studies have reported that porous hydroxyapatite (HA), with its special structure, implanted at ectopic (non-bone) sites, exhibits osteoinductive activity. However, few studies have examined the detailed ultrastructure of mineralized tissue formed in biomaterials like HA. Therefore, it is important to examine whether the mineralized tissue exhibits structural characteristics of normal bone tissue. Thus, in this study, we subcutaneously implanted hydroxyapatite blocks (5 x 5 x 7 mm) into the backs of adult dogs, and performed detailed morphological examination of the bone-like tissue formed, which showed a lamellar structure. Immunohistochemical staining revealed that the matrix fibers of the bone-like tissue were mainly composed of type I collagen. The pattern of crystal deposition in matrix fibers and the structure of osteoblast-, osteocyte-, bone-lining-, and osteoclast-like cells were similar to those of normal bone tissue and osteogenic cells, respectively. These results indicate that cellular events observed in normal bone formation and remodeling occur in bone-like tissue as well, and suggest that bone-like tissue in HA blocks is very similar to bone tissue. PMID:18634458

  11. Adsorption and conformational modification of fibronectin and fibrinogen adsorbed on hydroxyapatite. A QCM-D study.

    PubMed

    Fernández-Montes Moraleda, Belén; San Román, Julio; Rodríguez-Lorenzo, Luís M

    2016-10-01

    Hydroxyapatite is a bioactive ceramic frequently used for bone engineering/replacement. One of the parameters that influence the biological response to implanted materials is the conformation of the first adsorbed protein layer. In this work, the adsorption and conformational changes of two fibroid serum proteins; fibronectin and fibrinogen adsorbed onto four different hydroxyapatite powders are studied with a Quartz Crystal Microbalance with Dissipation (QCM-D). Each of the calcined apatites adsorbs less protein than their corresponding synthesized samples. Adsorption on synthesized samples yields always an extended conformation whereas a reorganization of the layer is observed for the calcined samples. Fg acquires a "Side on" conformation in all the samples at the beginning of the experiment except for one of the synthesized samples where an "End-on" conformation is obtained during the whole experiment. The Extended conformation is the active conformation for Fn. This conformation is favored by apatites with large specific surface area (SSA) and on highly concentrated media. Apatite surface features should be considered in the selection or design of materials for bone regeneration, since it is possible to control the conformation mode of attachment of Fn and Fg by an appropriate selection of them. © 2016 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 104A: 2585-2594, 2016. PMID:27254464

  12. Surface modification of yttria stabilized zirconia via polydopamine inspired coating for hydroxyapatite biomineralization

    NASA Astrophysics Data System (ADS)

    Zain, Norhidayu Muhamad; Hussain, Rafaqat; Kadir, Mohammed Rafiq Abdul

    2014-12-01

    Yttria stabilized zirconia (YSZ) has been widely used as biomedical implant due to its high strength and enhanced toughening characteristics. However, YSZ is a bioinert material which constrains the formation of chemical bonds with bone tissue following implantation. Inspired by the property of mussels, the surface of YSZ ceramics was functionalized by quinone-rich polydopamine to facilitate the biomineralization of hydroxyapatite. YSZ discs were first immersed in 2 mg/mL of stirred or unstirred dopamine solution at either 25 or 37 °C. The samples were then incubated in 1.5 simulated body fluid (SBF) for 7d. The effect of coating temperature for stirred and unstirred dopamine solutions during substrate grafting was investigated on the basis of chemical compositions, wettability and biomineralization of hydroxyapatite on the YSZ functionalized surface. The results revealed that the YSZ substrate grafted at 37 °C in stirred solution of dopamine possessed significantly improved hydrophilicity (water contact angle of 44.0 ± 2.3) and apatite-mineralization ability (apatite ratio of 1.78). In summary, the coating temperature and stirring condition during grafting procedure affected the chemical compositions of the films and thus influenced the formation of apatite layer on the substrate during the biomineralization process.

  13. Properties of carbon nanotube-dispersed Sr-hydroxyapatite injectable material for bone defects

    PubMed Central

    Raucci, M. G.; Alvarez-Perez, M.; Giugliano, D.; Zeppetelli, S.; Ambrosio, L.

    2016-01-01

    This study concerns the synthesis of gel materials based on carbon nanotubes dispersed strontium-modified hydroxyapatite (Sr-HA) at different compositions obtained by sol–gel technology and their influence on human-bone-marrow-derived mesenchymal stem cells. Furthermore, an evaluation of the influence of nanotubes and Strontium on physico-chemical, morphological, rheological and biological properties of hydroxyapatite gel was also performed. Morphological analysis (scanning electron microscopy) shows a homogeneous distribution of modified nanotubes in the ceramic matrix improving the bioactive properties of materials. The biological investigations proved that Sr-HA/carbon nanotube gel containing 0–20 mol (%) of Sr showed no toxic effect and promote the expression of early and late markers of osteogenic differentiation in cell culture performed in basal medium without osteogenic factors. Finally, the SrHA/carbon nanotube gels could have a good potential application as filler in bone repair and regeneration and may be used in the osteoporotic disease treatment. PMID:26816652

  14. Obtaining of biodegradable polylactide films and fibers filled hydroxyapatite for medical purposes

    SciTech Connect

    Lytkina, D. N. Shapovalova, Y. G. Rasskazova, L. A. Kurzina, I. A. Filimoshkin, A. G.

    2015-11-17

    Relevance of the work is due to the need for new materials that are used in medicine (orthopedics, surgery, dentistry, and others) as a substitute for natural bone tissue injuries, fractures, etc. The aim of presented work is developing of a method of producing biocompatible materials based on polyesters of hydroxycarboxylic acids and calcium phosphate ceramic (hydroxyapatite, HA) with homogeneous distribution of the inorganic component. Bioactive composites based on poly-L-lactide (PL) and hydroxyapatite with homogeneous distribution were prepared. The results of scanning electron microscopy confirm homogeneous distribution of the inorganic filler in the polymer matrix. The positive effect of ultrasound on the homogeneity of the composites was determined. The rate of hydrolysis of composites was evaluated. The rate of hydrolysis of polylactide as an individual substance is 7 times lower than the rate of hydrolysis of the polylactide as a part of the composite. It was found that materials submarines HA composite and do not cause a negative response in the cells of the immune system, while contributing to anti-inflammatory cytokines released by cells.

  15. Properties of carbon nanotube-dispersed Sr-hydroxyapatite injectable material for bone defects.

    PubMed

    Raucci, M G; Alvarez-Perez, M; Giugliano, D; Zeppetelli, S; Ambrosio, L

    2016-03-01

    This study concerns the synthesis of gel materials based on carbon nanotubes dispersed strontium-modified hydroxyapatite (Sr-HA) at different compositions obtained by sol-gel technology and their influence on human-bone-marrow-derived mesenchymal stem cells. Furthermore, an evaluation of the influence of nanotubes and Strontium on physico-chemical, morphological, rheological and biological properties of hydroxyapatite gel was also performed. Morphological analysis (scanning electron microscopy) shows a homogeneous distribution of modified nanotubes in the ceramic matrix improving the bioactive properties of materials. The biological investigations proved that Sr-HA/carbon nanotube gel containing 0-20 mol (%) of Sr showed no toxic effect and promote the expression of early and late markers of osteogenic differentiation in cell culture performed in basal medium without osteogenic factors. Finally, the SrHA/carbon nanotube gels could have a good potential application as filler in bone repair and regeneration and may be used in the osteoporotic disease treatment. PMID:26816652

  16. Obtaining of biodegradable polylactide films and fibers filled hydroxyapatite for medical purposes

    NASA Astrophysics Data System (ADS)

    Lytkina, D. N.; Shapovalova, Y. G.; Rasskazova, L. A.; Kurzina, I. A.; Filimoshkin, A. G.

    2015-11-01

    Relevance of the work is due to the need for new materials that are used in medicine (orthopedics, surgery, dentistry, and others) as a substitute for natural bone tissue injuries, fractures, etc. The aim of presented work is developing of a method of producing biocompatible materials based on polyesters of hydroxycarboxylic acids and calcium phosphate ceramic (hydroxyapatite, HA) with homogeneous distribution of the inorganic component. Bioactive composites based on poly-L-lactide (PL) and hydroxyapatite with homogeneous distribution were prepared. The results of scanning electron microscopy confirm homogeneous distribution of the inorganic filler in the polymer matrix. The positive effect of ultrasound on the homogeneity of the composites was determined. The rate of hydrolysis of composites was evaluated. The rate of hydrolysis of polylactide as an individual substance is 7 times lower than the rate of hydrolysis of the polylactide as a part of the composite. It was found that materials submarines HA composite and do not cause a negative response in the cells of the immune system, while contributing to anti-inflammatory cytokines released by cells.

  17. Hydrothermal synthesis of hydroxyapatite plates prepared using low molecular weight heparin (LMWH).

    PubMed

    Rajeswari, A; Kumar, V Ganesh; Karthick, V; Dhas, T Stalin; Potluri, Sri Lakshmi

    2013-11-01

    Materials with enhanced physical and biological properties have been used for biomedical applications and can be developed by functionalizing them using various components. Hydroxyapatite (HAP), among other available synthetic material, serves as one of the best tools in orthopaedics and ceramic coatings. The porous structure of HAP helps in bone cell regeneration, chemical integration of bone and also favours the interaction between bone and tissues. Herein, we have demonstrated a simple procedure for the synthesis of HAP using low molecular weight heparin (LMWH), a structural analogue of bone heparan sulphate proteoglycan. The presence of small sized HAP plates with well-defined structures was revealed using electron microscopic analysis. The phase purity of the synthesized HAP was evaluated using X-ray diffraction pattern obtained before and after immersion in simulated body fluid (SBF). PMID:23871522

  18. Nano-hydroxyapatite composite biomaterials for bone tissue engineering--a review.

    PubMed

    Venkatesan, Jayachandran; Kim, Se-Kwon

    2014-10-01

    In recent years, significant development has been achieved in the construction of artificial bone with ceramics, polymers and metals. Nano-hydroxyapatite (nHA) is widely used bioceramic material for bone graft substitute owing to its biocompatibility and osteoconductive properties. nHA with chitin, chitosan, collagen, gelatin, fibrin, polylactic acid, polycaprolactone, poly(lactic-co-glycolic) acid, polyamide, polyvinyl alcohol, polyurethane and polyhydroxybutyrate based composite scaffolds have been explored in the present review for bone graft substitute. This article further reviews the preparative methods, chemical interaction, biocompatibiity, biodegradation, alkaline phosphatase activity, mineralization effect, mechanical properties and delivery of nHA-based nanocomposites for bone tissue regeneration. The nHA based composite biomaterials proved to be promising biomaterials for bone tissue engineering. PMID:25992432

  19. Chemical characterization of silicon-substituted hydroxyapatite.

    PubMed

    Gibson, I R; Best, S M; Bonfield, W

    1999-03-15

    Bioceramic specimens have been prepared by incorporating a small amount of silicon (0.4 wt %) into the structure of hydroxyapatite [Ca10(PO4)6(OH)2, HA] via an aqueous precipitation reaction to produce a silicon-substituted hydroxyapatite (Si-HA). The results of chemical analysis confirmed the proposed substitution of the silicon (or silicate) ion for the phosphorus (or phosphate) ion in hydroxyapatite. The Si-HA was produced by first preparing a silicon-substituted apatite (Si-Ap) by a precipitation process. A single-phase Si-HA was obtained by heating/calcining the as-prepared Si-Ap to temperatures above 700 degrees C; no secondary phases, such as tricalcium phosphate (TCP), tetracalcium phosphate (TeCP), or calcium oxide (CaO), were observed by X-ray diffraction analysis. Although the X-ray diffraction patterns of Si-HA and stoichiometric HA appeared to be identical, refinement of the diffraction data revealed some small structural differences between the two materials. The silicon substitution in the HA lattice resulted in a small decrease in the a axis and an increase in the c axis of the unit cell. This substitution also caused a decrease in the number of hydroxyl (OH) groups in the unit cell, which was expected from the proposed substitution mechanism. The incorporation of silicon in the HA lattice resulted in an increase in the distortion of the PO4 tetrahedra, indicated by an increase in the distortion index. Analysis of the Si-HA by Fourier transform infrared (FTIR) spectroscopy indicated that although the amount of silicon incorporated into the HA lattice was small, silicon substitution appeared to affect the FTIR spectra of HA, in particular the P-O vibrational bands. The results demonstrate that phase-pure silicon-substituted hydroxyapatite may be prepared using a simple precipitation technique. PMID:10397946

  20. Identification of hydroxyapatite crystals in synovial fluid.

    PubMed

    Halverson, P B; McCarty, D J

    1979-04-01

    A semiquantitative technique employing (14C) ethane-1-hydroxy 1, -1-diphosphonate (EHDP) binding has been used to detect crystals, presumably hydroxyapatite, in human synovial fluid samples which were handled to prevent the formation of artifactual mineral phase. Binding material was found in 29% of non-inflammatory and in none of inflammatory joint fluids. Nuclide binding material was strongly correlated with the presence of CPPD crystals and with radiographic evidence of cartilaginous degeneration. PMID:106859

  1. Thin film ceramic thermocouples

    NASA Technical Reports Server (NTRS)

    Gregory, Otto (Inventor); Fralick, Gustave (Inventor); Wrbanek, John (Inventor); You, Tao (Inventor)

    2011-01-01

    A thin film ceramic thermocouple (10) having two ceramic thermocouple (12, 14) that are in contact with each other in at least on point to form a junction, and wherein each element was prepared in a different oxygen/nitrogen/argon plasma. Since each element is prepared under different plasma conditions, they have different electrical conductivity and different charge carrier concentration. The thin film thermocouple (10) can be transparent. A versatile ceramic sensor system having an RTD heat flux sensor can be combined with a thermocouple and a strain sensor to yield a multifunctional ceramic sensor array. The transparent ceramic temperature sensor that could ultimately be used for calibration of optical sensors.

  2. Ceramic gas turbine shroud

    DOEpatents

    Shi, Jun; Green, Kevin E.

    2014-07-22

    An example gas turbine engine shroud includes a first annular ceramic wall having an inner side for resisting high temperature turbine engine gasses and an outer side with a plurality of radial slots. A second annular metallic wall is positioned radially outwardly of and enclosing the first annular ceramic wall and has a plurality of tabs in communication with the slot of the first annular ceramic wall. The tabs of the second annular metallic wall and slots of the first annular ceramic wall are in communication such that the first annular ceramic wall and second annular metallic wall are affixed.

  3. Electrophoretic deposition of composite hydroxyapatite-chitosan coatings

    SciTech Connect

    Pang Xin; Zhitomirsky, Igor . E-mail: zhitom@mcmaster.ca

    2007-04-15

    Cathodic electrophoretic deposition has been utilized for the fabrication of composite hydroxyapatite-chitosan coatings on 316L stainless steel substrates. The addition of chitosan to the hydroxyapatite suspensions promoted the electrophoretic deposition of the hydroxyapatite nanoparticles and resulted in the formation of composite coatings. The obtained coatings were investigated by X-ray diffraction, thermogravimetric and differential thermal analysis, scanning and transmission electron microscopy, potentiodynamic polarization measurements, and electrochemical impedance spectroscopy. It was shown that the deposit composition can be changed by a variation of the chitosan or hydroxyapatite concentration in the solutions. Experimental conditions were developed for the fabrication of hydroxyapatite-chitosan nanocomposites containing 40.9-89.8 wt.% hydroxyapatite. The method enabled the formation of adherent and uniform coatings of thicknesses up to 60 {mu}m. X-ray studies revealed that the preferred orientation of the hydroxyapatite nanoparticles in the chitosan matrix increases with decreasing hydroxyapatite content in the composite coatings. The obtained coatings provided the corrosion protection for the 316L stainless steel substrates00.

  4. Adhesion to and decalcification of hydroxyapatite by carboxylic acids.

    PubMed

    Yoshida, Y; Van Meerbeek, B; Nakayama, Y; Yoshioka, M; Snauwaert, J; Abe, Y; Lambrechts, P; Vanherle, G; Okazaki, M

    2001-06-01

    Fundamental to the processes of decalcification of or adhesion to mineralized tissues is the molecular interaction of acids with hydroxyapatite. This study was undertaken to chemically analyze the interaction of 1 mono-, 2 di-, 1 tri-, and 2 polycarboxylic acids with hydroxyapatite in an attempt to elucidate the underlying mechanism. Maleic, citric, and lactic acid decalcified hydroxyapatite, in contrast to oxalic acid and the two polycarboxylic acids that were chemically bonded to hydroxyapatite. Solubility tests showed that the calcium salts of the former were very soluble, whereas those of the latter could hardly be dissolved in the respective acid solutions. Based on these data, an adhesion/decalcification concept was advanced that predicts that carboxylic acids, regardless of concentration/pH, either adhere to or decalcify hydroxyapatite, depending on the dissolution rate of the respective calcium salts in the acid solution. This contrasting behavior of organic acids most likely results from their differential structural conformations. PMID:11499514

  5. Methods of synthesizing hydroxyapatite powders and bulk materials

    DOEpatents

    Luo, P.

    1999-01-12

    Methods are provided for producing non-porous controlled morphology hydroxyapatite granules of less than 8 {micro}m by a spray-drying process. Solid or hollow spheres or doughnuts can be formed by controlling the volume fraction and viscosity of the slurry as well as the spray-drying conditions. Methods of providing for homogeneous cellular structure hydroxyapatite granules are also provided. Pores or channels or varying size and number can be formed by varying the temperature at which a hydroxyapatite slurry formed in basic, saturated ammonium hydroxide is spray-dried. Methods of providing non-porous controlled morphology hydroxyapatite granules in ammonium hydroxide are also provided. The hydroxyapatite granules and bulk materials formed by these methods are also provided. 26 figs.

  6. Methods of synthesizing hydroxyapatite powders and bulk materials

    DOEpatents

    Luo, Ping

    1999-01-12

    Methods are provided for producing non-porous controlled morphology hydroxyapatite granules of less than 8 .mu.m by a spray-drying process. Solid or hollow spheres or doughnuts can be formed by controlling the volume fraction and viscosity of the slurry as well as the spray-drying conditions. Methods of providing for homogenous cellular structure hydroxyapatite granules are also provided. Pores or channels or varying size and number can be formed by varying the temperature at which a hydroxyapatite slurry formed in basic, saturated ammonium hydroxide is spray-dried. Methods of providing non-porous controlled morphology hydroxyapatite granules in ammonium hydroxide are also provided. The hydroxyapatite granules and bulk materials formed by these methods are also provided.

  7. Effect of zeta potentials on bovine serum albumin adsorption to hydroxyapatite surfaces.

    PubMed

    Miyake, Nahoko; Sato, Toru; Maki, Yoshinobu

    2013-01-01

    The aim of the present study was to examine the adsorption of bovine serum albumin (BSA) to hydroxyapatite surfaces by means of zeta potential. The electrophoretic mobility of both hydroxyapatite and BSA were negative, with BSA itself less negative than hydroxyapatite. The zeta potential of the surface of BSA-adsorbed hydroxyapatite was significantly more negative than that of hydroxyapatite alone (p<0.0001). The BSA histogram indicated two negative peaks, and the zeta potential of BSA-adsorbed hydroxyapatite also showed two similar negative peaks. These results suggest that BSA adsorption to hydroxyapatite surfaces is related to electrostatic interaction. PMID:23903580

  8. Effects of ceramic component on cephalexin release from bioactive bone cement consisting of Bis-GMA/TEGDMA resin and bioactive glass ceramics.

    PubMed

    Otsuka, M; Fujita, H; Nakamura, T; Kokubo, T

    2001-01-01

    The purpose of this study was to elucidate the effect of amount of ceramic cement powder on drug release from bioactive bone cement. The associated bone-bonding strength was also investigated. The bioactive bone cement under investigation consisted of bisphenol-alpha-glycidyl methacrylate (Bis-GMA), triethylene-glycol dimethacrylate (TEGDMA) resin and a combination of apatite- and wollastonite-containing glass-ceramic (A-W GC) powder. A-W GC powder (50%, 70% and 80% w/w) containing 5% cephalexin (CEX) powder hardened within 5 min after mixing with Bis-GMA/TEGDMA resin. The compressive strength of the cement with or without drug increased with increasing the amount of ceramic powder. The compressive strength of the 80% ceramic cement without the incorporation of cephalexin was 194 MPa. This compressive strength was about 3 times higher than that for polymethylmethacrylate cement. After the cement was implanted in the proximal metaphysis of the tibiae of male rabbits, the failure load for the cement was found to increase with increasing of the amount of ceramic powder. This finding suggested that the cement formed a bonding with bone. In vitro CEX release from bioactive bone cement pellets in a simulated body fluid at pH 7.25 and 37 degrees C continued for more than 2 weeks. Drug release profile followed the Higuchi equation initially, but not at later stages. The drug release rate increased with increasing amount of ceramic powder in the mixture. Since the pore volume of the cement increased with increasing of amount of ceramic powder, the drug diffused in the pores between the ceramics particle and polymer matrix. As hydroxyapatite precipitated on the cement surface, the drug release rate decreased, as observed at the later release stage. These results suggest that varying the amount of ceramic powder in the cement system could control the drug release rate from bioactive bone cement. PMID:11281575

  9. The friction and wear of ceramic/ceramic and ceramic/metal combinations in sliding contact

    NASA Technical Reports Server (NTRS)

    Sliney, Harold E.; Dellacorte, Christopher

    1994-01-01

    The tribological characteristics of ceramics sliding on ceramics are compared to those of ceramics sliding on a nickel-based turbine alloy. The friction and wear of oxide ceramics and silicon-based ceramics in air at temperatures from room ambient to 900 C (in a few cases to 1200 C) were measured for a hemispherically-tipped pin on a flat sliding contact geometry. In general, especially at high temperature, friction and wear were lower for ceramic/metal combinations than for ceramic/ceramic combinations. The better tribological performance for ceramic/metal combinations is attributed primarily to the lubricious nature of the oxidized surface of the metal.

  10. The friction and wear of ceramic/ceramic and ceramic/metal combinations in sliding contact

    NASA Technical Reports Server (NTRS)

    Sliney, Harold E.; Dellacorte, Christopher

    1993-01-01

    The tribological characteristics of ceramics sliding on ceramics are compared to those of ceramics sliding on a nickel based turbine alloy. The friction and wear of oxide ceramics and silicon-based ceramics in air at temperatures from room ambient to 900 C (in a few cases to 1200 C) were measured for a hemispherically-tipped pin on a flat sliding contact geometry. In general, especially at high temperature, friction and wear were lower for ceramic/metal combinations than for ceramic/ceramic combinations. The better tribological performance for ceramic/metal combinations is attributed primarily to the lubricious nature of the oxidized surface of the metal.

  11. Study of hydroxyl carbonate apatite formation on bioactive glass coated dental ceramics by confocal laser scanning microscopy (CLSM)

    NASA Astrophysics Data System (ADS)

    Stanciu, G. A.; Savu, B.; Sandulescu, I.; Paraskevopoulos, K.; Koidis, P.

    2007-03-01

    Some dental ceramics were coated with a bioactive glass and resulted the formation of a stable and well bonded with the ceramic substrate thin layer. After immersion in a solution with ion concentrations similar to those of human blood plasma the development of hydroxy carbonate apatite layer on the surface of bioactive glass may be observed. The objective of this study was to investigate structural surface changes of bioactive glass, after exposure in a simulated body fluid for a different number of days. The roughness and topography of the hydroxyapatite surface were investigated by Confocal Scanning Laser Microscopy. The chemical composition was analyzed by Energy Dispersive Spectroscopy measurements.

  12. Ultrastructure of regenerated bone mineral surrounding hydroxyapatite-alginate composite and sintered hydroxyapatite.

    PubMed

    Rossi, Andre L; Barreto, Isabela C; Maciel, William Q; Rosa, Fabiana P; Rocha-Leão, Maria H; Werckmann, Jacques; Rossi, Alexandre M; Borojevic, Radovan; Farina, Marcos

    2012-01-01

    We report the ultrastructure of regenerated bone surrounding two types of biomaterials: hydroxyapatite-alginate composite and sintered hydroxyapatite. Critical defects in the calvaria of Wistar rats were filled with micrometer-sized spherical biomaterials and analyzed after 90 and 120 days of implantation by high-resolution transmission electron microscopy and Fourier transform infrared attenuated total reflectance microscopy, respectively. Infrared spectroscopy showed that hydroxyapatite of both biomaterials became more disordered after implantation in the rat calvaria, indicating that the biological environment induced modifications in biomaterials structure. We observed that the regenerated bone surrounding both biomaterials had a lamellar structure with type I collagen fibers alternating in adjacent lamella with angles of approximately 90°. In each lamella, plate-like apatite crystals were aligned in the c-axis direction, although a rotation around the c-axis could be present. Bone plate-like crystal dimensions were similar in regenerated bone around biomaterials and pre-existing bone in the rat calvaria. No epitaxial growth was observed around any of the biomaterials. A distinct mineralized layer was observed between new bone and hydroxyapatite-alginate biomaterial. This region presented a particular ultrastructure with crystallites smaller than those of the bulk of the biomaterial, and was possibly formed during the synthesis of alginate-containing composite or in the biological environment after implantation. Round nanoparticles were observed in regions of newly formed bone. The findings of this work contribute to a better understanding of the role of hydroxyapatite based biomaterials in bone regeneration processes at the nanoscale. PMID:22057083

  13. Properties of magnesium-substituted hydroxyapatite and the plasma coatings based on it

    NASA Astrophysics Data System (ADS)

    Lyasnikova, A. V.; Pichkhidze, S. Ya.; Dudareva, O. A.; Markelova, O. A.

    2015-11-01

    Magnesium-substituted hydroxyapatite is synthesized and deposited by plasma spraying, and the coating and the products of hydroxyapatite decomposition are analyzed. The phase composition of magnesium- substituted hydroxyapatite deposited by plasma spraying undergoes changes. The coating consisting of molten magnesium-substituted hydroxyapatite powder particles with pores between them has a homogeneous structure over the surface and throughout the internal structure and adhesion characteristics that exceed those of hydroxyapatite coatings.

  14. Role of SrO on the bioactivity behavior of some ternary borate glasses and their glass ceramic derivatives.

    PubMed

    Abdelghany, A M; Ouis, M A; Azooz, M A; ElBatal, H A; El-Bassyouni, G T

    2016-01-01

    Borate glasses containing SrO substituting both CaO and NaO were prepared and characterized for their bioactivity or bone bonding ability. Glass ceramic derivatives were prepared by thermal heat treatment process. FTIR, XRD and SEM measurements for the prepared glass and glass-ceramics before and after immersion in sodium phosphate solution for one and two weeks were carried out. The appearance of two IR peaks within the range 550-680cm(-1) after immersion in phosphate solution indicates the formation of hydroxyapatite or equivalent Sr phosphate layer. X-ray diffraction data agree with the FTIR spectral analysis. The solubility test was carried out for both glasses and glass ceramics derivatives in the same phosphate solution. The introduction of SrO increases the solubility for both glasses and glass ceramics and this is assumed to be due to the formation of Sr phosphate which is more soluble than calcium phosphate (hydroxyapatite). SEM images reveal varying changes in the surfaces of glass ceramics after immersion according to the SrO content. PMID:26204506

  15. Role of SrO on the bioactivity behavior of some ternary borate glasses and their glass ceramic derivatives

    NASA Astrophysics Data System (ADS)

    Abdelghany, A. M.; Ouis, M. A.; Azooz, M. A.; ElBatal, H. A.; El-Bassyouni, G. T.

    2016-01-01

    Borate glasses containing SrO substituting both CaO and NaO were prepared and characterized for their bioactivity or bone bonding ability. Glass ceramic derivatives were prepared by thermal heat treatment process. FTIR, XRD and SEM measurements for the prepared glass and glass-ceramics before and after immersion in sodium phosphate solution for one and two weeks were carried out. The appearance of two IR peaks within the range 550-680 cm-1 after immersion in phosphate solution indicates the formation of hydroxyapatite or equivalent Sr phosphate layer. X-ray diffraction data agree with the FTIR spectral analysis. The solubility test was carried out for both glasses and glass ceramics derivatives in the same phosphate solution. The introduction of SrO increases the solubility for both glasses and glass ceramics and this is assumed to be due to the formation of Sr phosphate which is more soluble than calcium phosphate (hydroxyapatite). SEM images reveal varying changes in the surfaces of glass ceramics after immersion according to the SrO content.

  16. Ceramic tamper-revealing seals

    DOEpatents

    Kupperman, David S.; Raptis, Apostolos C.; Sheen, Shuh-Haw

    1992-01-01

    A flexible metal or ceramic cable with composite ceramic ends, or a u-shaped ceramic connecting element attached to a binding element plate or block cast from alumina or zirconium, and connected to the connecting element by shrink fitting.

  17. Analyses of fine paste ceramics

    SciTech Connect

    Sabloff, J A

    1980-01-01

    Four chapters are included: history of Brookhaven fine paste ceramics project, chemical and mathematical procedures employed in Mayan fine paste ceramics project, and compositional and archaeological perspectives on the Mayan fine paste ceramics. (DLC)

  18. Superconductive ceramic oxide combination

    SciTech Connect

    Chatterjee, D.K.; Mehrotra, A.K.; Mir, J.M.

    1991-03-05

    This patent describes the combination of a superconductive ceramic oxide which degrades in conductivity upon contact of ambient air with its surface and, interposed between the ceramic oxide surface and ambient air in the amount of at least 1 mg per square meter of surface area of the superconductive ceramic oxide, a passivant polymer selected from the group consisting of a polyester ionomer and an alkyl cellulose.

  19. Ceramic Electron Multiplier

    DOE PAGESBeta

    Comby, G.

    1996-10-01

    The Ceramic Electron Multipliers (CEM) is a compact, robust, linear and fast multi-channel electron multiplier. The Multi Layer Ceramic Technique (MLCT) allows to build metallic dynodes inside a compact ceramic block. The activation of the metallic dynodes enhances their secondary electron emission (SEE). The CEM can be used in multi-channel photomultipliers, multi-channel light intensifiers, ion detection, spectroscopy, analysis of time of flight events, particle detection or Cherenkov imaging detectors. (auth)

  20. Continuous Fiber Ceramic Composites

    SciTech Connect

    2002-09-01

    Fiber-reinforced ceramic composites demonstrate the high-temperature stability of ceramics--with an increased fracture toughness resulting from the fiber reinforcement of the composite. The material optimization performed under the continuous fiber ceramic composites (CFCC) included a series of systematic optimizations. The overall goals were to define the processing window, to increase the robustinous of the process, to increase process yield while reducing costs, and to define the complexity of parts that could be fabricated.

  1. Electric field-assisted sintering of nanocrystalline hydroxyapatite for biomedical applications

    NASA Astrophysics Data System (ADS)

    Tran, Tien Bich

    As the main inorganic component of bone, hydroxyapatite (HA, Ca 10(PO4)6(OH)2) should be an ideal candidate in biomaterials selection. When grain sizes are in the nanometric regime, protein adsorption and cell adhesion are enhanced, while strength, hardness, and wear resistance are improved. Unfortunately, low phase stability, poor sinterability, and a tendency towards exaggerated grain coarsening challenge full densification of nanocrystalline hydroxyapatite by conventional sintering methods. The field-assisted sintering technique (FAST) has successfully consolidated a variety of nanocrystalline metals and ceramics in dramatically reduced times. The sintering enhancements observed during FAST can be attributed to thermal and athermal effects. The rapid heating rates (up to ˜1000ºC/min) afforded by FAST contribute a significant thermal effect. Since fast heating rates reduce powder exposure to sub-sintering temperatures, non-densifying surface diffusion is limited. The athermal effects of FAST are less well understood and can include plasma generation, dielectric breakdown, particle surface cleaning, grain boundary pinning, and space charge effects. Applying the field-assisted sintering technique to nanocrystalline hydroxyapatite yielded surprising results. Deviations from conventional densification behavior were observed, with dehydroxylation identified as the most deleterious process to densification as well as mechanical and biological performance. Since hydroxyapatite is not a stable phase at high temperatures and low water partial pressure atmospheres, desintering due to dehydroxylation-related pore formation became apparent during Stage III sintering. In fact, the degree of desintering and pore formation increased with the extent of Stage III sintering and grain growth. The atomic rearrangements taking place during grain boundary migration are believed to favor the formation of more-stable oxyapatite through hydroxyapatite dehydroxylation. This behavior was

  2. Alumina-based ceramic composite

    DOEpatents

    Alexander, Kathleen B.; Tiegs, Terry N.; Becher, Paul F.; Waters, Shirley B.

    1996-01-01

    An improved ceramic composite comprising oxide ceramic particulates, nonoxide ceramic particulates selected from the group consisting of carbides, borides, nitrides of silicon and transition metals and mixtures thereof, and a ductile binder selected from the group consisting of metallic, intermetallic alloys and mixtures thereof is described. The ceramic composite is made by blending powders of the ceramic particulates and the ductile to form a mixture and consolidating the mixture of under conditions of temperature and pressure sufficient to produce a densified ceramic composite.

  3. Method of sintering ceramic materials

    DOEpatents

    Holcombe, Cressie E.; Dykes, Norman L.

    1992-01-01

    A method for sintering ceramic materials is described. A ceramic article is coated with layers of protective coatings such as boron nitride, graphite foil, and niobium. The coated ceramic article is embedded in a container containing refractory metal oxide granules and placed within a microwave oven. The ceramic article is heated by microwave energy to a temperature sufficient to sinter the ceramic article to form a densified ceramic article having a density equal to or greater than 90% of theoretical density.

  4. Method of sintering ceramic materials

    DOEpatents

    Holcombe, C.E.; Dykes, N.L.

    1992-11-17

    A method for sintering ceramic materials is described. A ceramic article is coated with layers of protective coatings such as boron nitride, graphite foil, and niobium. The coated ceramic article is embedded in a container containing refractory metal oxide granules and placed within a microwave oven. The ceramic article is heated by microwave energy to a temperature sufficient to sinter the ceramic article to form a densified ceramic article having a density equal to or greater than 90% of theoretical density. 2 figs.

  5. Measuring Fracture Times Of Ceramics

    NASA Technical Reports Server (NTRS)

    Shlichta, Paul J.; Bister, Leo; Bickler, Donald G.

    1989-01-01

    Electrical measurements complement or replace fast cinematography. Electronic system measures microsecond time intervals between impacts of projectiles on ceramic tiles and fracture tiles. Used in research on ceramics and ceramic-based composite materials such as armor. Hardness and low density of ceramics enable them to disintegrate projectiles more efficiently than metals. Projectile approaches ceramic tile specimen. Penetrating foil squares of triggering device activate display and recording instruments. As ceramic and resistive film break oscilloscope plots increase in electrical resistance of film.

  6. Ceramic brush seals development

    NASA Technical Reports Server (NTRS)

    Howe, Harold

    1994-01-01

    The following topics are discussed in this viewgraph presentation: ceramic brush seals, research and development, manufacturing, brazed assembly development, controlling braze flow, fiber selection, and braze results.

  7. Corrosion of Ceramic Materials

    NASA Technical Reports Server (NTRS)

    Opila, Elizabeth J.; Jacobson, Nathan S.

    1999-01-01

    Non-oxide ceramics are promising materials for a range of high temperature applications. Selected current and future applications are listed. In all such applications, the ceramics are exposed to high temperature gases. Therefore it is critical to understand the response of these materials to their environment. The variables to be considered here include both the type of ceramic and the environment to which it is exposed. Non-oxide ceramics include borides, nitrides, and carbides. Most high temperature corrosion environments contain oxygen and hence the emphasis of this chapter will be on oxidation processes.

  8. Dry pressing technical ceramics

    SciTech Connect

    Lewis, W.A. Jr.

    1996-04-01

    Dry pressing of technical ceramics is a fundamental method of producing high-quality ceramic components. The goals of dry pressing technical ceramics are uniform compact size and green density, consistent part-to-part green density and defect-free compact. Dry pressing is the axial compaction of loosely granulated dry ceramic powders (< 3% free moisture) within a die/punch arrangement. The powder, under pressure, conforms to the specific shape of the punch faces and die. Powder compaction occurs within a rigid-walled die and usually between a top and bottom punch. Press configurations include anvil, rotary, multiple-punch and multiple-action.

  9. Defect production in ceramics

    SciTech Connect

    Zinkle, S.J.; Kinoshita, C.

    1997-08-01

    A review is given of several important defect production and accumulation parameters for irradiated ceramics. Materials covered in this review include alumina, magnesia, spinel silicon carbide, silicon nitride, aluminum nitride and diamond. Whereas threshold displacement energies for many ceramics are known within a reasonable level of uncertainty (with notable exceptions being AIN and Si{sub 3}N{sub 4}), relatively little information exists on the equally important parameters of surviving defect fraction (defect production efficiency) and point defect migration energies for most ceramics. Very little fundamental displacement damage information is available for nitride ceramics. The role of subthreshold irradiation on defect migration and microstructural evolution is also briefly discussed.

  10. Similar healthy osteoclast and osteoblast activity on nanocrystalline hydroxyapatite and nanoparticles of tri-calcium phosphate compared to natural bone

    PubMed Central

    MacMillan, Adam K; Lamberti, Francis V; Moulton, Julia N; Geilich, Benjamin M; Webster, Thomas J

    2014-01-01

    While there have been numerous studies to determine osteoblast (bone forming cell) functions on nanocrystalline compared to micron crystalline ceramics, there have been few studies which have examined osteoclast activity (including tartrate-resistant acid phosphatase, formation of resorption pits, size of resorption pits, and receptor activator of nuclear factor κB [RANK]). This is despite the fact that osteoclasts are an important part of maintaining healthy bone since they resorb bone during the bone remodeling process. Moreover, while it is now well documented that bone formation is enhanced on nanoceramics compared to micron ceramics, some have pondered whether osteoblast functions (such as osteoprotegerin and RANK ligand [RANKL]) are normal (ie, non-diseased) on such materials compared to natural bone. For these reasons, the objective of the present in vitro study was to determine various functions of osteoclasts and osteoblasts on nanocrystalline and micron crystalline hydroxyapatite as well as tri-calcium phosphate materials and compare such results to cortical and cancellous bone. Results showed for the first time similar osteoclast activity (including tartrate-resistant acid phosphatase, formation of resorption pits, size of resorption pits, and RANK) and osteoblast activity (osteoprotegerin and RANKL) on nanocrystalline hydroxyapatite compared to natural bone, whereas osteoclast and osteoblast functions on micron crystalline versions of these ceramics were much different than natural bone. In this manner, this study provides additional evidence that nanocrystalline calcium phosphates can serve as suitable synthetic analogs to natural bone to improve numerous orthopedic applications. It also provides the first data of healthy osteoclast and osteoblast functions on nanocrystalline calcium phosphates compared to natural bone. PMID:25506216

  11. Silk as a biocohesive sacrificial binder in the fabrication of hydroxyapatite load bearing scaffolds

    PubMed Central

    McNamara, Stephanie L.; Rnjak-Kovacina, Jelena; Schmidt, Daniel; Lo, Tim J.; Kaplan, David L.

    2014-01-01

    Limitations of current clinical methods for bone repair continue to fuel the demand for a high strength, bioactive bone replacement material. Recent attempts to produce porous scaffolds for bone regeneration have been limited by the intrinsic weakness associated with high porosity materials. In this study, ceramic scaffold fabrication techniques for potential use in load-bearing bone repairs have been developed using naturally derived silk from Bombyx mori. Silk was first employed for ceramic grain consolidation during green body formation, and later as a sacrificial polymer to impart porosity during sintering. These techniques allowed preparation of hydroxyapatite (HA) scaffolds that exhibited a wide range of mechanical and porosity profiles, with some displaying unusually high compressive strength up to 152.4 ± 9.1 MPa. Results showed that the scaffolds exhibited a wide range of compressive strengths and moduli (8.7 ± 2.7 MPa to 152.4 ± 9.1 MPa and 0.3 ± 0.1 GPa to 8.6 ± 0.3 GPa) with total porosities of up to 62.9 ± 2.7% depending on the parameters used for fabrication. Moreover, HA-silk scaffolds could be molded into large, complex shapes, and further machined post-sinter to generate specific three-dimensional geometries. Scaffolds supported bone marrow-derived mesenchymal stem cell attachment and proliferation, with no signs of cytotoxicity. Therefore, silk-fabricated HA scaffolds show promise for load bearing bone repair and regeneration needs. PMID:24881027

  12. Functionalizing Ti-surfaces through the EPD of hydroxyapatite/nanoY2O3.

    PubMed

    Parente, P; Sanchez-Herencia, A J; Mesa-Galan, M J; Ferrari, B

    2013-02-14

    Ceramic materials for skeletal repair and reconstruction are expanding to a number of different applications. Present research is addressing new compositions and performances to promote osseo-integration through metal coatings. Nanotechnology plays a key role in this research because nanostructures can be introduced into implants to functionalize them and/or to enhance their properties, such as the thermal or mechanical response. In this work, the insertion of Y(2)O(3) nanoparticles into a hydroxyapatite (HA) coating of Ti using colloidal processing technology was developed. The suspensions of HA and Y(2)O(3) nanoparticles were formulated with a focus on zeta potential, particle size distribution, and viscosity for the codeposition of both phases by electrophoresis. The microstructure of the nanocomposite coating was optimized by adjusting the main parameters of the electrophoretic deposition process. A threshold value of the applied electric field for the composite shaping was identified. The results demonstrate that the Y(2)O(3) nanoparticles are homogeneously distributed in the coating and decrease in concentration as the distance from the substrate increases. As a consequence of the presence of the Y(2)O(3), delays in the HA thermal decomposition and the improvement of metal-ceramic joining were observed. PMID:23140173

  13. Interaction of hydroxyapatite-titanium at elevated temperature in vacuum environment.

    PubMed

    Yang, Yunzhi; Kim, Kyo-Han; Agrawal, C Mauli; Ong, Joo L

    2004-07-01

    In this study, the interaction between hydroxyapatite (HA) and titanium (Ti) at elevated temperature in vacuum environment was investigated. The 80 wt% HA-20 wt% Ti powder mixtures and 90 wt% HA-10 wt% Ti powder mixtures were dry pressed and heat-treated at 1100 degrees C in vacuum environment. HA powders and the commercially pure Ti powders were used as controls. The heat-treated samples were characterized using X-ray diffraction (XRD), Fourier transform infrared spectroscopy, scanning electron microscope (SEM) and energy disperse spectra. XRD and SEM indicated densification of metallic Ti specimens during the in-vacuum heat treatment. Heat treatment of HA specimens in vacuum resulted in the loss of hydroxyl groups as well the formation of a secondary beta-tricalcium phosphate phase. Metallic Ti was not observed in the in-vacuum heat-treated HA-Ti specimens. However, alpha-tricalcium phosphate, tetracalcium phosphate and calcium titanium oxide were observed for the in-vacuum heat-treated HA-Ti specimens. It was concluded that the in-vacuum heat-treatment process completely converted the metal-ceramics composites to ceramic composites. PMID:14967524

  14. Development and characterization of hydroxyapatite/β-TCP/chitosan composites for tissue engineering applications.

    PubMed

    Shavandi, Amin; Bekhit, Alaa El-Din A; Ali, M Azam; Sun, Zhifa; Gould, Maree

    2015-11-01

    Calcium phosphate ceramics that mimic bone composition provide interesting possibilities for the advancement in bone tissue engineering. The present study reports on a chitosan composite reinforced by hydroxyapatite (HA) and β-tricalcium phosphate (β-TCP) obtained from waste mussel shells and cross-linked using tripolyphosphate (TPP). The ratios of the ceramic components in composites were 20/10/70, 30/20/50 and 40/30/30 (HA/β-TCP/CH, w/w %). Biodegradation rate, structural properties and in-vitro degradation of the bone-like composite scaffolds were investigated. The optimum amount of TPP required for composite was 2.5% and glycerol was used as plasticizer at an optimized concentration of 1%. Tripolyphosphate cross-linked chitosan composites were developed by freezing and lyophilisation. The Young's modulus of the scaffolds was increased from 4kPa to 17kPa and the porosity of composites dropped from 85 to 68% by increasing the HA/β-TCP ratio. After 28days in physiological solution, bone-like composite scaffolds with a higher ratio of HA/β-TCP (e.g. 40/30/30) showed about 2% lower biodegradation in comparison to scaffolds with a lower ratio of HA/β-TCP (i.e. 20/10/70). The obtained data suggest that the chitosan based bone-like composites could be potential candidates for biomedical applications. PMID:26249618

  15. Hydroxyapatite-silver nanoparticles coatings on porous polyurethane scaffold.

    PubMed

    Ciobanu, Gabriela; Ilisei, Simona; Luca, Constantin

    2014-02-01

    The present paper is focused on a study regarding the possibility of obtaining hydroxyapatite-silver nanoparticle coatings on porous polyurethane scaffold. The method applied is based on a combined strategy involving hydroxyapatite biomimetic deposition on polyurethane surface using a Supersaturated Calcification Solution (SCS), combined with silver ions reduction and in-situ crystallization processes on hydroxyapatite-polyurethane surface by sample immersing in AgNO3 solution. The morphology, composition and phase structure of the prepared samples were characterized by scanning electron microscopy coupled with energy dispersive X-ray spectroscopy (SEM-EDX), X-ray diffraction (XRD), UV-Vis spectroscopy and X-ray photoelectron spectroscopy (XPS) measurements. The data obtained show that a layer of hydroxyapatite was deposited on porous polyurethane support and the silver nanoparticles (average size 34.71 nm) were dispersed among and even on the hydroxyapatite crystals. Hydroxyapatite/polyurethane surface acts as a reducer and a stabilizing agent for silver ions. The surface plasmon resonance peak in UV-Vis absorption spectra showed an absorption maximum at 415 nm, indicating formation of silver nanoparticles. The hydroxyapatite-silver polyurethane scaffolds were tested against Staphylococcus aureus and Escherichia coli and the obtained data were indicative of good antibacterial properties of the materials. PMID:24411349

  16. Ceramic Technology Project

    SciTech Connect

    Not Available

    1992-03-01

    The Ceramic Technology Project was developed by the USDOE Office of Transportation Systems (OTS) in Conservation and Renewable Energy. This project, part of the OTS's Materials Development Program, was developed to meet the ceramic technology requirements of the OTS's automotive technology programs. Significant accomplishments in fabricating ceramic components for the USDOE and NASA advanced heat engine programs have provided evidence that the operation of ceramic parts in high-temperature engine environments is feasible. These programs have also demonstrated that additional research is needed in materials and processing development, design methodology, and data base and life prediction before industry will have a sufficient technology base from which to produce reliable cost-effective ceramic engine components commercially. A five-year project plan was developed with extensive input from private industry. In July 1990 the original plan was updated through the estimated completion of development in 1993. The objective is to develop the industrial technology base required for reliable ceramics for application in advanced automotive heat engines. The project approach includes determining the mechanisms controlling reliability, improving processes for fabricating existing ceramics, developing new materials with increased reliability, and testing these materials in simulated engine environments to confirm reliability. Although this is a generic materials project, the focus is on the structural ceramics for advanced gas turbine and diesel engines, ceramic bearings and attachments, and ceramic coatings for thermal barrier and wear applications in these engines. To facilitate the rapid transfer of this technology to US industry, the major portion of the work is being done in the ceramic industry, with technological support from government laboratories, other industrial laboratories, and universities.

  17. Hydroxyapatite Reinforced Coatings with Incorporated Detonationally Generated Nanodiamonds

    SciTech Connect

    Pramatarova, L.; Pecheva, E.; Hikov, T.; Fingarova, D.; Dimitrova, R.; Spassov, T.; Krasteva, N.; Mitev, D.

    2010-01-21

    We studied the effect of the substrate chemistry on the morphology of hydroxyapatite-detonational nanodiamond composite coatings grown by a biomimetic approach (immersion in a supersaturated simulated body fluid). When detonational nanodiamond particles were added to the solution, the morphology of the grown for 2 h composite particles was porous but more compact then that of pure hydroxyapatite particles. The nanodiamond particles stimulated the hydroxyapatite growth with different morphology on the various substrates (Ti, Ti alloys, glasses, Si, opal). Biocompatibility assay with MG63 osteoblast cells revealed that the detonational nanodiamond water suspension with low and average concentration of the detonational nanodiamond powder is not toxic to living cells.

  18. In-situ deposition of hydroxyapatite on graphene nanosheets

    PubMed Central

    Neelgund, Gururaj M.; Oki, Aderemi; Luo, Zhiping

    2014-01-01

    Graphene nanosheets were effectively functionalized by in-situ deposition of hydroxyaptite through a facile chemical precipitation method. Prior to grafting of hydroxyapatite, chemically modified graphene nanosheets were obtained by the reduction of graphene oxide in presence of ethylenediamine. The resulting hydroxyapatite functionalized graphene nanosheets were characterized by attenuated total reflection IR spectroscopy, X-ray diffraction, field emission scanning electron microscopy, transmission electron microscopy, X-ray energy dispersive spectroscopy, Raman spectroscopy and thermogravimetric analysis. These characterization techniques revealed the successful grafting of hydroxyapatite over well exfoliated graphene nanosheets without destroying their structure. PMID:25110359

  19. Hydroxyapatite Reinforced Coatings with Incorporated Detonationally Generated Nanodiamonds

    NASA Astrophysics Data System (ADS)

    Pramatarova, L.; Pecheva, E.; Dimitrova, R.; Spassov, T.; Krasteva, N.; Hikov, T.; Fingarova, D.; Mitev, D.

    2010-01-01

    We studied the effect of the substrate chemistry on the morphology of hydroxyapatite-detonational nanodiamond composite coatings grown by a biomimetic approach (immersion in a supersaturated simulated body fluid). When detonational nanodiamond particles were added to the solution, the morphology of the grown for 2 h composite particles was porous but more compact then that of pure hydroxyapatite particles. The nanodiamond particles stimulated the hydroxyapatite growth with different morphology on the various substrates (Ti, Ti alloys, glasses, Si, opal). Biocompatibility assay with MG63 osteoblast cells revealed that the detonational nanodiamond water suspension with low and average concentration of the detonational nanodiamond powder is not toxic to living cells.

  20. EXAFS study of structural disorder in carbonate-containing hydroxyapatites.

    PubMed

    Harries, J E; Hasnain, S S; Shah, J S

    1987-12-01

    A structural characterization of pure hydroxyapatite and partially carbonated hydroxyapatites has been performed using EXAFS spectroscopy, X-ray diffraction, and infrared spectroscopy. Our findings show that marked structural changes within the hydroxyapatite unit cell accompany the substitution of the phosphate anion. Extended X-ray Absorption Fine Structure (EXAFS) spectroscopy has shown that the incorporation of carbonate into the phosphate site alters the structural geometry beyond the nearest neighbor oxygen coordination to calcium in a manner consistent with an increase in structural disorder. The nearest neighbor coordination to calcium is not detectably affected by the presence of carbonate. PMID:2830003

  1. An X-ray electron study of nanodisperse hydroxyapatite

    NASA Astrophysics Data System (ADS)

    Melikhov, I. V.; Teterin, Yu. A.; Rudin, V. N.; Teterin, A. Yu.; Maslakov, K. I.; Severin, A. V.

    2009-01-01

    Two states of surface valence electrons localized on faces with different molecular reliefs were observed for nanodisperse hydroxyapatite. Thermal treatment of nanocrystals caused a shift Δ E b = 0.5 eV of the spectrum of valence electrons on molecularly rough faces and a shift of 0.8 eV of the spectrum from smooth faces. Similar electron spectrum shifts were observed for sorption, in particular, of sodium succinate. These results are of importance for the diagnostics of various hydroxyapatite kinds, since hydroxyapatite is a constituent mineral component of living organisms, and for the synthesis of medicines with enhanced biological activity used in treatment of various bone diseases.

  2. Evolving application of biomimetic nanostructured hydroxyapatite

    PubMed Central

    Roveri, Norberto; Iafisco, Michele

    2010-01-01

    By mimicking Nature, we can design and synthesize inorganic smart materials that are reactive to biological tissues. These smart materials can be utilized to design innovative third-generation biomaterials, which are able to not only optimize their interaction with biological tissues and environment, but also mimic biogenic materials in their functionalities. The biomedical applications involve increasing the biomimetic levels from chemical composition, structural organization, morphology, mechanical behavior, nanostructure, and bulk and surface chemical–physical properties until the surface becomes bioreactive and stimulates cellular materials. The chemical–physical characteristics of biogenic hydroxyapatites from bone and tooth have been described, in order to point out the elective sides, which are important to reproduce the design of a new biomimetic synthetic hydroxyapatite. This review outlines the evolving applications of biomimetic synthetic calcium phosphates, details the main characteristics of bone and tooth, where the calcium phosphates are present, and discusses the chemical–physical characteristics of biomimetic calcium phosphates, methods of synthesizing them, and some of their biomedical applications. PMID:24198477

  3. Ceramics for engines

    NASA Technical Reports Server (NTRS)

    Kiser, James D.; Levine, Stanley R.; Dicarlo, James A.

    1990-01-01

    The NASA Lewis Research Center's Ceramic Technology Program is focused on aerospace propulsion and power needs. Thus, emphasis is on high-temperature ceramics and their structural and environmental durability and reliability. The program is interdisciplinary in nature with major emphasis on materials and processing, but with significant efforts in design methodology and life prediction.

  4. Fabrication Of Ceramic Mats

    NASA Technical Reports Server (NTRS)

    Collins, Earl R., Jr.

    1991-01-01

    Process to make mats of fine zirconia filaments proposed. Ceramic mats formed by sintering mats of partially dried filaments extruded from slurry of ceramic powder, binder, and solvent. Mats of fine zirconia fibers easier to ball-mill than commercially available zirconia powder.

  5. Industrial Ceramics: Secondary Schools.

    ERIC Educational Resources Information Center

    New York City Board of Education, Brooklyn, NY. Bureau of Curriculum Development.

    The expanding use of ceramic products in today's world can be seen in the areas of communications, construction, aerospace, textiles, metallurgy, atomic energy, and electronics. The demands of science have brought ceramics from an art to an industry using mass production and automated processes which requires the services of great numbers as the…

  6. Improved mechanical properties of hydroxyapatite/poly(ɛ-caprolactone) scaffolds by surface modification of hydroxyapatite

    NASA Astrophysics Data System (ADS)

    Wang, Yan; Dai, Jing; Zhang, Qingchun; Xiao, Yan; Lang, Meidong

    2010-08-01

    Scaffolds comprising hydroxyapatite (HAP) or poly(ɛ-caprolactone)-grafted hydroxyapatite (g-HAP) and poly(ɛ-caprolactone) (PCL) were prepared using the thermally induced phase separation/salt leaching technique. The g-HAP nanoparticles were evaluated by Fourier Transformation Infrared Spectroscopy (FTIR) and thermal gravimetric analysis (TGA). Power X-ray Diffraction (XRD) patterns confirmed the successful grafting on the surface of HAP. The effects on mechanical strength, porosity and thermal property of scaffolds by the introduction of nanoparticles were extensively investigated. The compressive modulus of the scaffold was greatly improved by the addition of g-HAP nanoparticles. Especially the compressive modulus of the g-HAP/PCL scaffold containing 20 wt% of g-HAP was 59.4% higher than that of the corresponding HAP/PCL scaffold.

  7. Method of making a modified ceramic-ceramic composite

    DOEpatents

    Weaver, Billy L.; McLaughlin, Jerry C.; Stinton, David P.

    1995-01-01

    The present invention provides a method of making a shaped ceramic-ceramic composite articles, such as gas-fired radiant heat burner tubes, heat exchangers, flame dispersers, and other furnace elements, having a formed-on ceramic-ceramic composite thereon.

  8. Ceramic heat exchanger

    DOEpatents

    LaHaye, P.G.; Rahman, F.H.; Lebeau, T.P.; Severin, B.K.

    1998-06-16

    A tube containment system is disclosed. The tube containment system does not significantly reduce heat transfer through the tube wall. The contained tube is internally pressurized, and is formed from a ceramic material having high strength, high thermal conductivity, and good thermal shock resistance. The tube containment system includes at least one ceramic fiber braid material disposed about the internally pressurized tube. The material is disposed about the tube in a predetermined axial spacing arrangement. The ceramic fiber braid is present in an amount sufficient to contain the tube if the tube becomes fractured. The tube containment system can also include a plurality of ceramic ring-shaped structures, in contact with the outer surface of the tube, and positioned between the tube and the ceramic fiber braid material, and/or at least one transducer positioned within tube for reducing the internal volume and, therefore, the energy of any shrapnel resulting from a tube fracture. 6 figs.

  9. Ceramic heat exchanger

    DOEpatents

    LaHaye, Paul G.; Rahman, Faress H.; Lebeau, Thomas P. E.; Severin, Barbara K.

    1998-01-01

    A tube containment system. The tube containment system does not significantly reduce heat transfer through the tube wall. The contained tube is internally pressurized, and is formed from a ceramic material having high strength, high thermal conductivity, and good thermal shock resistance. The tube containment system includes at least one ceramic fiber braid material disposed about the internally pressurized tube. The material is disposed about the tube in a predetermined axial spacing arrangement. The ceramic fiber braid is present in an amount sufficient to contain the tube if the tube becomes fractured. The tube containment system can also include a plurality of ceramic ring-shaped structures, in contact with the outer surface of the tube, and positioned between the tube and the ceramic fiber braid material, and/or at least one transducer positioned within tube for reducing the internal volume and, therefore, the energy of any shrapnel resulting from a tube fracture.

  10. Mounting for ceramic scroll

    DOEpatents

    Petty, Jack D.

    1993-01-01

    A mounting for a ceramic scroll on a metal engine block of a gas turbine engine includes a first ceramic ring and a pair of cross key connections between the first ceramic ring, the ceramic scroll, and the engine block. The cross key connections support the scroll on the engine block independent of relative radial thermal growth and for bodily movement toward an annular mounting shoulder on the engine. The scroll has an uninterrupted annular shoulder facing the mounting shoulder on the engine block. A second ceramic ring is captured between mounting shoulder and the uninterrupted shoulder on the scroll when the latter is bodily shifted toward the mouting shoulder to define a gas seal between the scroll and the engine block.

  11. Strain isolated ceramic coatings

    NASA Technical Reports Server (NTRS)

    Tolokan, R. P.; Brady, J. B.; Jarrabet, G. P.

    1985-01-01

    Plasma sprayed ceramic coatings are used in gas turbine engines to improve component temperature capability and cooling air efficiency. A compliant metal fiber strain isolator between a plasma sprayed ceramic coating and a metal substrate improves ceramic durability while allowing thicker coatings for better insulation. Development of strain isolated coatings has concentrated on design and fabrication of coatings and coating evaluation via thermal shock testing. In thermal shock testing, five types of failure are possible: buckling failure im compression on heat up, bimetal type failure, isothermal expansion mismatch failure, mudflat cracking during cool down, and long term fatigue. A primary failure mode for thermally cycled coatings is designated bimetal type failure. Bimetal failure is tensile failure in the ceramic near the ceramic-metal interface. One of the significant benefits of the strain isolator is an insulating layer protecting the metal substrate from heat deformation and thereby preventing bimetal type failure.

  12. Synthesis of porous hydroxyapatites by combination of gelcasting and foams burn out methods.

    PubMed

    Padilla, S; Román, J; Vallet-Regí, M

    2002-12-01

    The biocompatibility and the osteoconductive behavior of hydroxyapatite (OHAp) ceramics are well established. Bioceramics made of OHAp are available in dense and porous form. Recently it has been proved that the volume of bone ingrowth at early times is primarily interconnectivity dependent. A new method for the obtention of porous OHAp ceramics that combine the in situ polymerization (gel casting method) and the foams burn out is proposed. Four polyurethane foams with different cells/cm were used. The foams were fully filled of an OHAp polymerizable suspension that after gelled produced very homogeneous and strong green bodies. After different thermal treatments the green bodies yield porous OHAp ceramics that were a replica of the foams used. Materials used in this work were studied by X-ray diffraction (XRD), X-ray fluorescence (XRF), scanning electron microscopy (SEM), N(2) adsorption isotherm, particle size distribution, and Hg porosimetry. Porous pieces of OHAp obtained are constituted by polyhedral-like particles (0.45-1.0 microm) that are surrounded by an interconnected network of pores. A bimodal distribution of the pores size between 30.8-58.6 and 1.0-1.2 microm has been observed. The size of the interconnected pores (30.8-58.6 microm) was controlled as a function of the cells/cm of the foam while the volume of the small pores was modified as a function of the sintering time. The presence of pores could promote the bone ingrowth and also could be used to insert different drugs, which makes these porous pieces a potential candidate to be used as non-load-bearing bone implants and as drug delivery systems. PMID:15348665

  13. Nano-particle doped hydroxyapatite material evaluation using spectroscopic polarization sensitive optical coherence tomography

    NASA Astrophysics Data System (ADS)

    Strąkowska, Paulina; Trojanowski, Michał; Gardas, Mateusz; Głowacki, Maciej J.; Kraszewski, Maciej; Strąkowski, Marcin R.

    2015-03-01

    Bio-ceramics such as hydroxyapatite (HAp) are widely used materials in medical applications, especially as an interface between implants and living tissues. There are many ways of creating structures from HAp like electrochemical assisted deposition, biomimetic, electrophoresis, pulsed laser deposition or sol-gel processing. Our research is based on analyzing the parameters of the sol-gel method for creating thin layers of HAp. In order to achieve this, we propose to use Optical Coherence Tomography (OCT) for non-destructive and non-invasive evaluation. Our system works in the IR spectrum range, which is helpful due to the wide range of nanocomposites being opaque in the VIS range. In order to use our method we need to measure two samples, one which is a reference HAp solution and second: a similar HAp solution with nanoparticles introduced inside. We use silver nanoparticles below 300 nm. The aim of this research is to analyze the concentration and dispersion of nanodopants in the bio-ceramic matrix. Furthermore, the quality of the HAp coating and deposition process repetition have been monitored. For this purpose the polarization sensitive OCT with additional spectroscopic analysis is being investigated. Despite the other methods, which are suitable for nanocomposite materials evaluation, the OCT with additional features seems to be one of the few which belong to the NDE/NDT group. Here we are presenting the OCT system for evaluation of the HAp with nano-particles, as well as HAp manufacturing process. A brief discussion on the usefulness of OCT for bio-ceramics materials examination is also being presented.

  14. Carbonate Hydroxyapatite and Silicon-Substituted Carbonate Hydroxyapatite: Synthesis, Mechanical Properties, and Solubility Evaluations

    PubMed Central

    Bang, L. T.; Long, B. D.; Othman, R.

    2014-01-01

    The present study investigates the chemical composition, solubility, and physical and mechanical properties of carbonate hydroxyapatite (CO3Ap) and silicon-substituted carbonate hydroxyapatite (Si-CO3Ap) which have been prepared by a simple precipitation method. X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), X-ray fluorescence (XRF) spectroscopy, and inductively coupled plasma (ICP) techniques were used to characterize the formation of CO3Ap and Si-CO3Ap. The results revealed that the silicate (SiO44−) and carbonate (CO32−) ions competed to occupy the phosphate (PO43−) site and also entered simultaneously into the hydroxyapatite structure. The Si-substituted CO3Ap reduced the powder crystallinity and promoted ion release which resulted in a better solubility compared to that of Si-free CO3Ap. The mean particle size of Si-CO3Ap was much finer than that of CO3Ap. At 750°C heat-treatment temperature, the diametral tensile strengths (DTS) of Si-CO3Ap and CO3Ap were about 10.8 ± 0.3 and 11.8 ± 0.4 MPa, respectively. PMID:24723840

  15. Topography, wetting, and corrosion responses of electrodeposited hydroxyapatite and fluoridated hydroxyapatite on magnesium.

    PubMed

    Assadian, Mahtab; Jafari, Hassan; Ghaffari Shahri, Seyed Morteza; Idris, Mohd Hasbullah; Almasi, Davood

    2016-08-12

    In this study, different types of calcium-phosphate phases were coated on NaOH pre-treated pure magnesium. The coating was applied by electrodeposition method in order to provide higher corrosion resistance and improve biocompatibility for magnesium. Thickness, surface morphology and topography of the coatings were analyzed using optical, scanning electron and atomic-force microscopies, respectively. Composition and chemical bonding, crystalline structures and wettability of the coatings were characterized using energy-dispersive and attenuated total reflectance-Fourier transform infrared spectroscopies, grazing incidence X-ray diffraction and contact angle measurement, respectively. Degradation behavior of the coated specimens was also investigated by potentiodynamic polarization and immersion tests. The experiments proved the presence of a porous coating dominated by dicalcium-phosphate dehydrate on the specimens. It was also verified that the developed hydroxyapatite was crystallized by alkali post-treatment. Addition of supplemental fluoride to the coating electrolyte resulted in stable and highly crystallized structures of fluoridated hydroxyapatite. The coatings were found effective to improve biocompatibility combined with corrosion resistance of the specimens. Noticeably, the fluoride supplemented layer was efficient in lowering corrosion rate and increasing surface roughness of the specimens compared to hydroxyapatite and dicalcium-phosphate dehydrates layers. PMID:27567782

  16. [Study on an injectable biomimetic hydroxyapatite--atelocollagen composite].

    PubMed

    Maier, S S; Pelin, Irina; Bulacovschi, V

    2007-01-01

    The paper presents a procedure for preparing mineralized collagen nanofibrils, mixed with deficient nanoparticulate calcium hydroxyapatite in a ratio close to that found in living bone structures. Such a composition might represent an injectable osteoconductive constituent, used in surgical kits for bone reconstruction. The FT-IR spectra of the prepared composite reveals a weak absorption at 871.82 cm(-1), indicating the nucleation of hydroxy-apatite at the acidic atelocollagen functions. More than that, a 45 cm(-1) ipsochromic shift of carboxylic band suggest a strong ionic interaction with hydroxyapatite. The X-Ray spectra show a high resemblance between the synthetic composite and the Fluka hydroxyapatite, but only for 2theta angles higher than 30 degrees. Below that value the protein presence induce crystalline disorders. PMID:18389809

  17. Formation of pyrophosphate on hydroxyapatite with thioesters as condensing agents

    NASA Technical Reports Server (NTRS)

    Weber, A. L.

    1982-01-01

    'Energy-rich' thioesters are shown to act as condensing agents in the formation of pyrophosphate on hydroxyapatite in the presence of water at ambient temperature. The yield of pyrophosphate based on thioester ranges from 2.5% to 11.4% and depends upon the pH and concentration of reactants. Reaction of 0.130 M hydroxyapatite suspended in a solution of 0.08 M sodium phosphate and 0.20 M imidazole hydrochloride (pH 7.0) with 0.10 M N,S-diacetylcysteamine for 6 days gives the highest yield of pyrophosphate (11.4%). Pyrophosphate formation requires the presence of hydroxyapatite, sodium phosphate and the thioester, N,S-diacetylcysteamine. The related thioester, N,S-diacetylcysteine, also yields pyrophosphate in reactions on hydroxyapatite.

  18. Synthesis of mesoporous nano-hydroxyapatite by using zwitterions surfactant

    EPA Science Inventory

    Mesoporous nano-hydroxyapatite (mn-HAP) was successfully synthesized via a novel micelle-templating method using lauryl dimethylaminoacetic acid as zwitterionic surfactant. The systematic use of such a surfactant in combination with microwave energy inputenables the precise contr...

  19. Preparation and characterization of collagen-hydroxyapatite/pectin composite.

    PubMed

    Wenpo, Feng; Gaofeng, Liang; Shuying, Feng; Yuanming, Qi; Keyong, Tang

    2015-03-01

    Pectin, a kind of plant polysaccharide, was introduced into collagen-hydroxyapatite composite system, and prepared collagen-hydroxyapatite/pectin (Col-HA/pectin) composite in situ. The structure of the composite was investigated by XRD, SEM, and FT-IR. The mechanical properties, water absorption, enzyme degradation, and cytotoxicity of the composite were investigated as well. The results show that the inorganic substance in the composite materials is hydroxyapatite in relatively low crystallinity. A new interface appeared by the interaction among hydroxyapatite and collagen-pectin, and formed smooth fine particles. The mechanical properties, water absorption, enzyme degradation, and cytotoxicity indicate a potential use in bone replacement for the new composite. PMID:25485944

  20. Formation of hydroxyapatite in various aqueous solutions

    NASA Astrophysics Data System (ADS)

    Sturgeon, Jacqueline Lee

    Hydroxyapatite (HAp), Ca10(PO4)6(OH) 2, is important in the field of biomaterials as it is the mineral component of bones and teeth. Biological apatites do not maintain an exact composition and are usually calcium-deficient, represented as Ca(10- x)(HPO 4)x(PO4)(6-x)(OH)(2-x), where x ranges from 0 to 1, with various ion substitutions. Formation of calcium-deficient hydroxyapatites (CDHAp) from solid calcium phosphate precursor materials was performed at physiologic temperature (37°C) in a variety of aqueous solutions. Two cement systems were utilized in these experiments: tetralcium phosphate (TetCP) with dicalcium phosphate anhydrous (DCPA) and beta-tricalcium phosphate (beta-TCP). The kinetics, solution chemistry, phase evolution, and microstructure of the developed apatites were analyzed as appropriate. Reaction of beta-TCP in ammonium fluoride solutions formed HAp substituted with fluoride and calculated to be deficient in calcium. A new ratio of TetCP to DCPA was used with solutions of sodium bicarbonate to form a calcium-deficient carbonate hydroxyapatite. The capacity for sodium dihydrogen phosphate to buffer pH increases and enhance reaction kinetics in this system was also explored. Formation of a highly crystalline CDHAp was achieved by hydrolyzing beta-TCP in water for extended time periods. Lattice parameters were among the features characterized for this apatite. The hydrolysis of beta-TCP in phosphate buffered saline (PBS) and simulated body fluids (SBF) was also investigated; use of SBF was found to completely inhibit formation of HAp in this system while reaction in PBS was slow in comparison to water. The effects of filler materials on the mechanical properties of a calcium phosphate cement were examined using the TetCP/DCPA system. Dense aggregates were not found to decrease compressive strength in comparison to the cement alone. The use of aggregates was found to improve the compressive strength of cement formed using NaHCO3 solution as a

  1. Experimental maxillary sinus augmentation using a highly bioactive glass ceramic.

    PubMed

    Vivan, Rodrigo Ricci; Mecca, Carlos Eduardo; Biguetti, Claudia Cristina; Rennó, Ana Claudia Muniz; Okamoto, Roberta; Cavenago, Bruno Cavalini; Duarte, Marco Húngaro; Matsumoto, Mariza Akemi

    2016-02-01

    Physicochemical characteristics of a biomaterial directly influence its biological behavior and fate. However, anatomical and physiological particularities of the recipient site also seem to contribute with this process. The present study aimed to evaluate bone healing of maxillary sinus augmentation using a novel bioactive glass ceramic in comparison with a bovine hydroxyapatite. Bilateral sinus augmentation was performed in adult male rabbits, divided into 4 groups according to the biomaterial used: BO-particulate bovine HA Bio-Oss(®) (BO), BO+G-particulate bovine HA + particulate autogenous bone graft (G), BS-particulate glass ceramic (180-212 μm) Biosilicate(®) (BS), and BS+G-particulate glass ceramic + G. After 45 and 90 days, animals were euthanized and the specimens prepared to be analyzed under light and polarized microscopy, immunohistochemistry, scanning electron microscopy (SEM), and micro-computed tomography (μCT). Results revealed different degradation pattern between both biomaterials, despite the association with bone graft. BS caused a more intense chronic inflammation with foreign body reaction, which led to a difficulty in bone formation. Besides this evidence, SEM and μCT confirmed direct contact between newly formed bone and biomaterial, along with osteopontin and osteocalcin immunolabeling. Bone matrix mineralization was late in BS group but became similar to BO at day 90. These results clearly indicate that further studies about Biosilicate(®) are necessary to identify the factors that resulted in an unfavorable healing response when used in maxillary sinus augmentation. PMID:26712707

  2. Mechanical characterization of hydroxyapatite, thermoelectric materials and doped ceria

    NASA Astrophysics Data System (ADS)

    Fan, Xiaofeng

    For a variety of applications of brittle ceramic materials, porosity plays a critical role structurally and/or functionally, such as in engineered bone scaffolds, thermoelectric materials and in solid oxide fuel cells. The presence of porosity will affect the mechanical properties, which are essential to the design and application of porous brittle materials. In this study, the mechanical property versus microstructure relations for bioceramics, thermoelectric (TE) materials and solid oxide fuel cells were investigated. For the bioceramic material hydroxyapatite (HA), the Young's modulus was measured using resonant ultrasound spectroscopy (RUS) as a function of (i) porosity and (ii) microcracking damage state. The fracture strength was measured as a function of porosity using biaxial flexure testing, and the distribution of the fracture strength was studied by Weibull analysis. For the natural mineral tetrahedrite based solid solution thermoelectric material (Cu10Zn2As4S13 - Cu 12Sb4S13), the elastic moduli, hardness and fracture toughness were studied as a function of (i) composition and (ii) ball milling time. For ZiNiSn, a thermoelectric half-Heusler compound, the elastic modulus---porosity and hardness---porosity relations were examined. For the solid oxide fuel cell material, gadolina doped ceria (GDC), the elastic moduli including Young's modulus, shear modulus, bulk modulus and Poisson's ratio were measured by RUS as a function of porosity. The hardness was evaluated by Vickers indentation technique as a function of porosity. The results of the mechanical property versus microstructure relations obtained in this study are of great importance for the design and fabrication of reliable components with service life and a safety factor. The Weibull modulus, which is a measure of the scatter in fracture strength, is the gauge of the mechanical reliability. The elastic moduli and Poisson's ratio are needed in analytical or numerical models of the thermal and

  3. Synthesis and characterization of TEP-EDTA-regulated bioactive hydroxyapatite

    NASA Astrophysics Data System (ADS)

    Haders, Daniel Joseph, II

    Hydroxyapatite (HA), Ca10(PO4)6(OH) 2, the stoichiometric equivalent of the ceramic phase of bone, is the preferred material for hard tissue replacement due to its bioactivity. However, bioinert metals are utilized in load-bearing orthopedic applications due to the poor mechanical properties of HA. Consequently, attention has been given to HA coatings for metallic orthopedic implants to take advantage of the bioactivity of HA and the mechanical properties of metals. Commercially, the plasma spray process (PS-HA) is the method most often used to deposit HA films on metallic implants. Since its introduction in the 1980's, however, concerns have been raised about the consequences of PS-HA's low crystallinity, lack of phase purity, lack of film-substrate chemical adhesion, passivation properties, and difficulty in coating complex geometries. Thus, there is a need to develop inexpensive reproducible next-generation HA film deposition techniques, which deposit high crystallinity, phase pure, adhesive, passivating, conformal HA films on clinical metallic substrates. The aim of this dissertation was to intelligently synthesize and characterize the material and biological properties of HA films on metallic substrates synthesized by hydrothermal crystallization, using thermodynamic phase diagrams as the starting point. In three overlapping interdisciplinary studies the potential of using ethylenediamine-tetraacetic acid/triethyl phosphate (EDTA/TEP) doubly regulated hydrothermal crystallization to deposit HA films, the TEP-regulated, time-and-temperature-dependent process by which films were deposited, and the bioactivity of crystallographically engineered films were investigated. Films were crystallized in a 0.232 molal Ca(NO3)2-0.232 molal EDTA-0.187 molal TEP-1.852 molal KOH-H2O chemical system at 200°C. Thermodynamic phase diagrams demonstrated that the chosen conditions were expected to produce Ca-P phase pure HA, which was experimentally confirmed. EDTA regulation of

  4. Novel doped hydroxyapatite thin films obtained by pulsed laser deposition

    NASA Astrophysics Data System (ADS)

    Duta, L.; Oktar, F. N.; Stan, G. E.; Popescu-Pelin, G.; Serban, N.; Luculescu, C.; Mihailescu, I. N.

    2013-01-01

    We report on the synthesis of novel ovine and bovine derived hydroxyapatite thin films on titanium substrates by pulsed laser deposition for a new generation of implants. The calcination treatment applied to produce the hydroxyapatite powders from ovine/bovine bones was intended to induce crystallization and to prohibit the transmission of diseases. The deposited films were characterized by scanning electron microscopy, X-ray diffraction, Fourier transform infrared spectroscopy, and energy dispersive X-ray spectroscopy. Pull-off adherence and profilometry measurements were also carried out. X-ray diffraction ascertained the polycrystalline hydroxyapatite nature of the powders and films. Fourier transform infrared spectroscopy evidenced the vibrational bands characteristic to a hydroxyapatite material slightly carbonated. The micrographs of the films showed a uniform distribution of spheroidal particulates with a mean diameter of ∼2 μm. Pull-off measurements demonstrated excellent bonding strength values between the hydroxyapatite films and the titanium substrates. Because of their physical-chemical properties and low cost fabrication from renewable resources, we think that these new coating materials could be considered as a prospective competitor to synthetic hydroxyapatite used for implantology applications.

  5. In situ deposition of hydroxyapatite on graphene nanosheets

    SciTech Connect

    Neelgund, Gururaj M.; Oki, Aderemi; Luo, Zhiping

    2013-02-15

    Graphical abstract: A facile chemical precipitation method is reported for effective in situ deposition of hydroxyapatite on graphene nanosheets. Prior to grafting of hydroxyapatite, chemically modified graphene nanosheets were obtained by the reduction of graphene oxide in presence of ethylenediamine. Display Omitted Highlights: ► It is a facile and effective method for deposition of HA on GR nanosheets. ► It avoids the use of harmful reducing agents like hydrazine, NaBH{sub 4} etc. ► GR nanosheets were produced using bio-compatible, ethylenediamine. ► The graphitic structure of synthesized GR nanosheets was high ordered. ► The ratio of Ca to P in HA was 1.64, which is close to ratio in natural bone. -- Abstract: Graphene nanosheets were effectively functionalized by in situ deposition of hydroxyapatite through a facile chemical precipitation method. Prior to grafting of hydroxyapatite, chemically modified graphene nanosheets were obtained by the reduction of graphene oxide in presence of ethylenediamine. The resulting hydroxyapatite functionalized graphene nanosheets were characterized by attenuated total reflection IR spectroscopy, X-ray diffraction, field emission scanning electron microscopy, transmission electron microscopy, X-ray energy dispersive spectroscopy, Raman spectroscopy and thermogravimetric analysis. These characterization techniques revealed the successful grafting of hydroxyapatite over well exfoliated graphene nanosheets without destroying their structure.

  6. Suspension thermal spraying of hydroxyapatite: microstructure and in vitro behaviour.

    PubMed

    Bolelli, Giovanni; Bellucci, Devis; Cannillo, Valeria; Lusvarghi, Luca; Sola, Antonella; Stiegler, Nico; Müller, Philipp; Killinger, Andreas; Gadow, Rainer; Altomare, Lina; De Nardo, Luigi

    2014-01-01

    In cementless fixation of metallic prostheses, bony ingrowth onto the implant surface is often promoted by osteoconductive plasma-sprayed hydroxyapatite coatings. The present work explores the use of the innovative High Velocity Suspension Flame Spraying (HVSFS) process to coat Ti substrates with thin homogeneous hydroxyapatite coatings. The HVSFS hydroxyapatite coatings studied were dense, 27-37μm thick, with some transverse microcracks. Lamellae were sintered together and nearly unidentifiable, unlike conventional plasma-sprayed hydroxyapatite. Crystallinities of 10%-70% were obtained, depending on the deposition parameters and the use of a TiO2 bond coat. The average hardness of layers with low (<24%) and high (70%) crystallinity was ≈3.5GPa and ≈4.5GPa respectively. The distributions of hardness values, all characterised by Weibull modulus in the 5-7 range, were narrower than that of conventional plasma-sprayed hydroxyapatite, with a Weibull modulus of ≈3.3. During soaking in simulated body fluid, glassy coatings were progressively resorbed and replaced by a new, precipitated hydroxyapatite layer, whereas coatings with 70% crystallinity were stable up to 14days of immersion. The interpretation of the precipitation behaviour was also assisted by surface charge assessments, performed through Z-potential measurements. During in vitro tests, HA coatings showed no cytotoxicity towards the SAOS-2 osteoblast cell line, and surface cell proliferation was comparable with proliferation on reference polystyrene culture plates. PMID:24268261

  7. High pressure ceramic joint

    DOEpatents

    Ward, M.E.; Harkins, B.D.

    1993-11-30

    Many recuperators have components which react to corrosive gases and are used in applications where the donor fluid includes highly corrosive gases. These recuperators have suffered reduced life, increased service or maintenance, and resulted in increased cost. The present joint when used with recuperators increases the use of ceramic components which do not react to highly corrosive gases. Thus, the present joint used with the present recuperator increases the life, reduces the service and maintenance, and reduces the increased cost associated with corrosive action of components used to manufacture recuperators. The present joint is comprised of a first ceramic member, a second ceramic member, a mechanical locking device having a groove defined in one of the first ceramic member and the second ceramic member. The joint and the mechanical locking device is further comprised of a refractory material disposed in the groove and contacting the first ceramic member and the second ceramic member. The present joint mechanically provides a high strength load bearing joint having good thermal cycling characteristics, good resistance to a corrosive environment and good steady state strength at elevated temperatures. 4 figures.

  8. High pressure ceramic joint

    DOEpatents

    Ward, Michael E.; Harkins, Bruce D.

    1993-01-01

    Many recuperators have components which react to corrosive gases and are used in applications where the donor fluid includes highly corrosive gases. These recuperators have suffered reduced life, increased service or maintenance, and resulted in increased cost. The present joint when used with recuperators increases the use of ceramic components which do not react to highly corrosive gases. Thus, the present joint used with the present recuperator increases the life, reduces the service and maintenance, and reduces the increased cost associated with corrosive action of components used to manufacture recuperators. The present joint is comprised of a first ceramic member, a second ceramic member, a mechanical locking device having a groove defined in one of the first ceramic member and the second ceramic member. The joint and the mechanical locking device is further comprised of a refractory material disposed in the groove and contacting the first ceramic member and the second ceramic member. The present joint mechanically provides a high strength load bearing joint having good thermal cycling characteristics, good resistance to a corrosive environment and good steady state strength at elevated temperatures.

  9. All-ceramic crowns.

    PubMed

    Lehner, C R; Schärer, P

    1992-06-01

    Despite the good appearance and biocompatibility of dental porcelains, failures are still of considerable concern because of some limited properties common to all-ceramic crown systems. As in the years before, pertinent scientific articles published between November 1990 and December 1991 focused on strengthening mechanisms and compared fracture toughness for different ceramic systems by using various test methods. Some evaluated the clinical implications thereon for seating and loading crowns and measured wear against different ceramic surface conditions. Recently introduced with pleasing aesthetic qualities, IPS-Empress (Ivoclar, Schaan, Liechtenstein), a new European leucite-reinforced glass-ceramic, has finally drawn attention in some journals and has been reviewed with promising in vitro test results. Using a simple press-molding technique, well-fitting crowns, inlays, and veneers can be fabricated without an additional ceramming procedure. Again, only long-term clinical trials will validate achievements compared with other all-ceramic systems and with well-established metal ceramics. PMID:1325848

  10. Ceramic-silicide composites

    SciTech Connect

    Petrovic, J.J.

    1998-12-01

    The area of ceramic-silicide composites represents a merging of structural ceramics and structural silicides. Such ceramic-silicide composites can possess the desirable characteristics of both classes of compounds. Important structural ceramics are materials such as Si{sub 3}N{sub 4}, SiC, Al{sub 2}O{sub 3}, and ZrO{sub 2}, which possess covalent, ionic, or mixed covalent-ionic atomic bonding. An important structural silicide is MoSi{sub 2}, which possesses mixed covalent-metallic bonding. The arena of ceramic-silicide composites encompasses both composites where the structural silicide is the matrix and the structural ceramic is the reinforcement, and composites where the structural ceramic is the matrix and the structural silicide is the reinforcement. In the former area, MoSi{sub 2}-SiC, MoSi{sub 2}-ZrO{sub 2}, and MoSi{sub 2}-Al{sub 2}O{sub 3} composites are discussed. In the latter area, Si{sub 3}N{sub 4}-MoSi{sub 2} composites are described.

  11. Adhesion behaviors of Escherichia coli on hydroxyapatite.

    PubMed

    Kamitakahara, Masanobu; Takahashi, Shohei; Yokoi, Taishi; Inoue, Chihiro; Ioku, Koji

    2016-04-01

    Optimum design of support materials for microorganisms is required for the construction of bioreactors. However, the effects of support materials on microorganisms are still unclear. In this study, we investigated the adhesion behavior of Escherichia coli (E. coli) on hydroxyapatite (HA), polyurethane (PU), poly(vinyl chloride) (PVC), and carbon (Carbon) to obtain basic knowledge for the design of support materials. The total metabolic activity and number of E. coli adhering on the samples followed the order of HA ≈ Carbon>PVC>PU. On the other hand, the water contact angle of the pellet surfaces followed the order of HA

  12. First principles study of hydroxyapatite surface.

    PubMed

    Slepko, Alexander; Demkov, Alexander A

    2013-07-28

    The biomineral hydroxyapatite (HA) [Ca10(PO4)6(OH)2] is the main mineral constituent of mammal bone. We report a theoretical investigation of the HA surface. We identify the low energy surface orientations and stoichiometry under a variety of chemical environments. The surface most stable in the physiologically relevant OH-rich environment is the OH-terminated (1000) surface. We calculate the work function of HA and relate it to the surface composition. For the lowest energy OH-terminated surface we find the work function of 5.1 eV, in close agreement with the experimentally reported range of 4.7 eV-5.1 eV [V. S. Bystrov, E. Paramonova, Y. Dekhtyar, A. Katashev, A. Karlov, N. Polyaka, A. V. Bystrova, A. Patmalnieks, and A. L. Kholkin, J. Phys.: Condens. Matter 23, 065302 (2011)]. PMID:23902010

  13. Novel method of preparing hydroxyapatite foams.

    PubMed

    Muthutantri, Anushini; Huang, Jie; Edirisinghe, Mohan

    2008-04-01

    Porous scaffolds are considered a key strategy in the concept of bone tissue engineering. Hydroxyapatite, which is a bioceramic has been used as a popular scaffold material due to its bioactive and osteoconductive properties. A combination of slurry-dipping and electrospraying has been used as a new foam fabrication method to produce porous and interconnected foam structures. The combined method has shown to overcome the shortcomings of the individual methods and it has produced open pores in the desired range of 100-350 microm. The porosity which was determined by calculation and microtomography was between 84% and 88%. Reduced cracks and thicker struts were observed in the microstructure, pointing to improved mechanical properties. PMID:18214644

  14. Hydroxyapatite deposition disease of the joint.

    PubMed

    Molloy, Eamonn S; McCarthy, Geraldine M

    2003-06-01

    Basic calcium phosphate (BCP) crystals include partially carbonate-substituted hydroxyapatite, octacalcium phosphate, and tricalcium phosphate. They may form deposits, which are frequently asymptomatic but may give rise to a number of clinical syndromes including calcific periarthritis, Milwaukee shoulder syndrome, and osteoarthritis, in and around joints. Recent data suggest that magnesium whitlockite, another form of BCP, may play a pathologic role in arthritis. Data from the past year have provided further understanding of the mechanisms by which BCP crystals induce inflammation and degeneration. There remains no specific treatment to modify the effects of BCP crystals. Although potential drugs are being identified as the complex pathophysiology of BCP crystals is unraveled, much work remains to be done in order to translate research advances to date into tangible clinical benefits. PMID:12744814

  15. Mechanism of incorporation of zinc into hydroxyapatite.

    PubMed

    Matsunaga, Katsuyuki; Murata, Hidenobu; Mizoguchi, Teruyasu; Nakahira, Atsushi

    2010-06-01

    The atomic level mechanism of incorporation of Zn(2+) into hydroxyapatite (HAp), which is a potential dopant to promote bone formation, was investigated, based on first principles total energy calculations and experimental X-ray absorption near edge structure (XANES) analyses. It was found that Zn(2+)-doped HAp tends to have a Ca-deficient chemical composition and substitutional Zn(2+) ions are associated with a defect complex with a Ca(2+) vacancy and two charge compensating protons. Moreover, first principles calculations demonstrated that Zn(2+) incorporation into HAp can take place by occupying the Ca(2+) vacancy of the defect complex. The Ca(2+) vacancy complex is not only the origin of the calcium deficiency in HAp, but also plays a key role in the uptake of trace elements during mineralization. PMID:19944784

  16. Effect of hydroxyapatite microcrystals on macrophage activity.

    PubMed

    Fukuchi, N; Akao, M; Sato, A

    1995-01-01

    Hydroxyapatite (HAp) microcrystals were synthesized by a neutralization reaction of Ca(OH)2 suspension and H3PO4 solution using an ultrasonic homogenizer. The in vitro interaction of HAp microcrystals with rat peritoneal macrophages was investigated by measuring the viability, acid phosphatase (ACP) activity, lactate dehydrogenase (LDH) activity and intracellular calcium content. HAp calcined at 800 degrees C and alpha-alumina particles (alumina) were used as comparative materials. Macrophages actively phagocytosed HAp microcrystals by dissolving them. However, no damage in macrophages exposed to HAp microcrystals was observed by transmission electron microscopy. Macrophages in the presence of HAp microcrystals showed less ACP and LDH activity and higher intracellular calcium content than those in the presence of calcined HAp and alumina. HAp microcrystals had excellent biocompatibility to macrophages as well as sintered HAp. PMID:8785507

  17. Thermal Diffusivity in Bone and Hydroxyapatite

    NASA Astrophysics Data System (ADS)

    Calderón, A.; Peña Rodríguez, G.; Muñoz Hernández, R. A.; Díaz Gongora, J. A. I.; Mejia Barradas, C. M.

    2004-09-01

    We report thermal diffusivity measurements in bull bone and commercial hydroxyapatite (HA), both in powder form, in order to determinate the thermal compatibility between these materials. Besides this, we report a comparison between these measured values and those of metallic samples frequently used in implants, as high purity titanium and stainless steel. Our results show a good thermal compatibility (74%) between HA and bone, both in powder form. Finally, it was obtained a one order of magnitude difference between the thermal diffusivity values of metallic samples and those corresponding values to bone and HA being this difference greater in titanium than in stainless steel, which is important to consider in some biomedical and dental applications.

  18. The Adsorption of Polyelectrolytes on Hydroxyapatite Crystals.

    PubMed

    Tsortos; Nancollas

    1999-01-01

    The adsorption of two polyelectrolytes, poly-L-Glutamate and poly-L-Aspartate, on hydroxyapatite (HAP) crystals was studied both experimentally and theoretically. Langmuir adsorption isotherms were obtained for both these molecules, with binding constants K = 6 x 10(6) and 3 x 10(6) M-1, respectively, at 37.0 degreesC, pH 7.4, and 0.15 M ionic strength. A theoretical analysis of the data, based on a model proposed by Hesselink, suggested a "train-loop" type of adsorption with non-electrostatic energy terms 3.51 and 4.76 (kT) for poly-L-Glu and poly-L-Asp, respectively. Copyright 1999 Academic Press. PMID:9878142

  19. Poly(vinyl alcohol) hydrogel coatings with tunable surface exposure of hydroxyapatite

    PubMed Central

    Moreau, David; Villain, Arthur; Ku, David N; Corté, Laurent

    2014-01-01

    Insufficient bone anchoring is a major limitation of artificial substitutes for connective osteoarticular tissues. The use of coatings containing osseoconductive ceramic particles is one of the actively explored strategies to improve osseointegration and strengthen the bone-implant interface for general tissue engineering. Our hypothesis is that hydroxyapatite (HA) particles can be coated robustly on specific assemblies of PVA hydrogel fibers for the potential anchoring of ligament replacements. A simple dip-coating method is described to produce composite coatings made of microscopic hydroxyapatite (HA) particles dispersed in a poly(vinyl alcohol) (PVA) matrix. The materials are compatible with the requirements for implant Good Manufacturing Practices. They are applied to coat bundles of PVA hydrogel fibers used for the development of ligament implants. By means of optical and electronic microscopy, we show that the coating thickness and surface state can be adjusted by varying the composition of the dipping solution. Quantitative analysis based on backscattered electron microscopy show that the exposure of HA at the coating surface can be tuned from 0 to over 55% by decreasing the weight ratio of PVA over HA from 0.4 to 0.1. Abrasion experiments simulating bone-implant contact illustrate how the coating cohesion and wear resistance increase by increasing the content of PVA relative to HA. Using pullout experiments, we find that these coatings adhere well to the fiber bundles and detach by propagation of a crack inside the coating. These results provide a guide to select coated implants for anchoring artificial ligaments. PMID:25482413

  20. Poly(vinyl alcohol) hydrogel coatings with tunable surface exposure of hydroxyapatite.

    PubMed

    Moreau, David; Villain, Arthur; Ku, David N; Corté, Laurent

    2014-01-01

    Insufficient bone anchoring is a major limitation of artificial substitutes for connective osteoarticular tissues. The use of coatings containing osseoconductive ceramic particles is one of the actively explored strategies to improve osseointegration and strengthen the bone-implant interface for general tissue engineering. Our hypothesis is that hydroxyapatite (HA) particles can be coated robustly on specific assemblies of PVA hydrogel fibers for the potential anchoring of ligament replacements. A simple dip-coating method is described to produce composite coatings made of microscopic hydroxyapatite (HA) particles dispersed in a poly(vinyl alcohol) (PVA) matrix. The materials are compatible with the requirements for implant Good Manufacturing Practices. They are applied to coat bundles of PVA hydrogel fibers used for the development of ligament implants. By means of optical and electronic microscopy, we show that the coating thickness and surface state can be adjusted by varying the composition of the dipping solution. Quantitative analysis based on backscattered electron microscopy show that the exposure of HA at the coating surface can be tuned from 0 to over 55% by decreasing the weight ratio of PVA over HA from 0.4 to 0.1. Abrasion experiments simulating bone-implant contact illustrate how the coating cohesion and wear resistance increase by increasing the content of PVA relative to HA. Using pullout experiments, we find that these coatings adhere well to the fiber bundles and detach by propagation of a crack inside the coating. These results provide a guide to select coated implants for anchoring artificial ligaments. PMID:25482413

  1. Fluoride removal performance of glass derived hydroxyapatite

    SciTech Connect

    Liang, Wen; Zhan, Lei; Piao, Longhua; Russel, Christian

    2011-02-15

    Research highlights: {yields} Novel sodium calcium borate glass derived hydroxyapatite (G-HAP) is prepared. {yields} Micro-G-HAP adsorbs F{sup -} ions in solutions more effectively than commercial nano-HAP. {yields} The adsorption kinetics and isotherms are well fitted by a second order kinetic model and Freundlich isotherm model. -- Abstract: A novel sodium calcium borate glass derived hydroxyapatite (G-HAP) with different ranges of particle size was prepared by immersion sodium calcium borate glass in 0.1 M K{sub 2}HPO{sub 4} solution by the ratio of 50 g L{sup -1} for 7 days. The unique advantage of G-HAP for the adsorption of fluoride ions in solutions was studied. The effects of size and quantity of particles, pH value and adsorption time on adsorption performance were investigated. The maximum adsorption capacity was 17.34 mg g{sup -1} if 5 g L{sup -1}, <100 {mu}m G-HAP was added to a solution with an initial pH value of 6.72 and the adsorption time was 12 h. The results showed that the micro-G-HAP could immobilize F{sup -} in solution more effectively than commercial nano-HAP, which makes potential application of the G-HAP in removing the fluoride ions from wastewater. The adsorption kinetics and isotherms for F{sup -} could be well fitted by a second order kinetic model and Freundlich isotherm model respectively, which could be used to describe the adsorption behavior. The mechanism of G-HAP in immobilizing F{sup -} from aqueous solutions was investigated by the X-ray diffraction (XRD), infrared spectra (IR) and scanning electron microscopy (SEM).

  2. Spacecraft ceramic protective shield

    NASA Technical Reports Server (NTRS)

    Larriva, Rene F. (Inventor); Nelson, Anne (M.); Czechanski, James G. (Inventor); Poff, Ray E. (Inventor)

    1995-01-01

    A low areal density protective shield apparatus, and method for making same, for protecting spacecraft structures from impact with hypervelocity objects, including a bumper member comprising a bumper ceramic layer, a bumper shock attenuator layer, and a bumper confining layer. The bumper ceramic layer can be SiC or B.sub.4 C; the bumper shock attenuator layer can be zirconia felt; and the bumper confining layer can be aluminum. A base armor member can be spaced from the bumper member and a ceramic fiber-based curtain can be positioned between the bumper and base armor members.

  3. Effects of chronic passive smoking on the regeneration of rat femoral defects filled with hydroxyapatite and stimulated by laser therapy.

    PubMed

    Franco, G R; Laraia, I O; Maciel, A A W; Miguel, N M; Dos Santos, G R; Fabrega-Carvalho, C A; Pinto, C A L; Pettian, M S; Cunha, M R

    2013-07-01

    Defects associated with bone mass loss are frequently treated by autogenous bone grafting. However, synthetic biomaterials such as calcium phosphate ceramics can substitute autologous grafts as long as they are biocompatible with bone tissue. In addition, low-level laser therapy (LLLT) is used to enhance bone regeneration by stimulating the local microcirculation and increasing the synthesis of collagen by bone cells. However, bone health is fundamental for osseointegration of the graft and bone repair. In this respect, excessive tobacco consumption can compromise expected outcomes because of its deleterious effects on bone metabolism that predispose to the development of osteoporosis. The objective of this study was to evaluate the regeneration of bone defects implanted with biomaterial and stimulated by LLLT in rats submitted to passive cigarette smoking. Porous hydroxyapatite granules were implanted into critical-size defects induced experimentally in the distal epiphysis of the right femur of 20 female Wistar rats submitted to passive smoking for 8 months in a smoking box. The defect site was irradiated with a gallium-arsenide laser at an intensity of 5.0 J/cm2. The animals were divided into four groups: control (non-smoking) rates submitted (G2) or not (G1) to laser irradiation, and smoking rats submitted (G4) or not (G3) to laser irradiation. The animals were sacrificed 8 weeks after biomaterial implantation. The right femurs were removed for photodocumentation, radiographed, and processed for routine histology. The results showed good radiopacity of the implant site and of the hydroxyapatite granules. Histologically, formation of new trabecular bone was observed adjacent to the hydroxyapatite granules in G1 and G2. In G3 and G4, the granules were surrounded mainly by connective tissue. In conclusion, passive smoking compromised bone neoformation in the defects and the LLLT protocol was not adequate to stimulate local osteogenesis. PMID:23340234

  4. Bioactive ceramic-reinforced composites for bone augmentation

    PubMed Central

    Tanner, K. E.

    2010-01-01

    Biomaterials have been used to repair the human body for millennia, but it is only since the 1970s that man-made composites have been used. Hydroxyapatite (HA)-reinforced polyethylene (PE) is the first of the ‘second-generation’ biomaterials that have been developed to be bioactive rather than bioinert. The mechanical properties have been characterized using quasi-static, fatigue, creep and fracture toughness testing, and these studies have allowed optimization of the production method. The in vitro and in vivo biological properties have been investigated with a range of filler content and have shown that the presence of sufficient bioactive filler leads to a bioactive composite. Finally, the material has been applied clinically, initially in the orbital floor and later in the middle ear. From this initial combination of HA in PE other bioactive ceramic polymer composites have been developed. PMID:20591846

  5. Ceramic Solar Receiver

    NASA Technical Reports Server (NTRS)

    Robertson, C., Jr.

    1984-01-01

    Solar receiver uses ceramic honeycomb matrix to absorb heat from Sun and transfer it to working fluid at temperatures of 1,095 degrees and 1,650 degrees C. Drives gas turbine engine or provides heat for industrial processes.

  6. Light emitting ceramic device

    DOEpatents

    Valentine, Paul; Edwards, Doreen D.; Walker, Jr., William John; Slack, Lyle H.; Brown, Wayne Douglas; Osborne, Cathy; Norton, Michael; Begley, Richard

    2010-05-18

    A light-emitting ceramic based panel, hereafter termed "electroceramescent" panel, is herein claimed. The electroceramescent panel is formed on a substrate providing mechanical support as well as serving as the base electrode for the device. One or more semiconductive ceramic layers directly overlay the substrate, and electrical conductivity and ionic diffusion are controlled. Light emitting regions overlay the semiconductive ceramic layers, and said regions consist sequentially of a layer of a ceramic insulation layer and an electroluminescent layer, comprised of doped phosphors or the equivalent. One or more conductive top electrode layers having optically transmissive areas overlay the light emitting regions, and a multi-layered top barrier cover comprising one or more optically transmissive non-combustible insulation layers overlay said top electrode regions.

  7. Ceramic breeder materials

    SciTech Connect

    Johnson, C.E.

    1990-01-01

    The breeding blanket is a key component of the fusion reactor because it directly involves tritium breeding and energy extraction, both of which are critical to development of fusion power. The lithium ceramics continue to show promise as candidate breeder materials. This promise was recognized by the International Thermonuclear Reactor (ITER) design team in its selection of ceramics as the first option for the ITER breeder material. Blanket design studies have indicated properties in the candidate materials data base that need further investigation. Current studies are focusing on tritium release behavior at high burnup, changes in thermophysical properties with burnup, compatibility between the ceramic breeder and beryllium multiplier, and phase changes with burnup. Laboratory and in-reactor tests, some as part of an international collaboration for development of ceramic breeder materials, are underway. 32 refs., 1 fig., 1 tab.

  8. Corrosion resistant ceramic materials

    DOEpatents

    Kaun, Thomas D.

    1995-01-01

    Ceramic materials which exhibit stability in severely-corrosive environments having high alkali-metal activity, high sulfur/sulfide activity and/or molten halides at temperatures of 200.degree.-550.degree. C. or organic salt (including SO.sub.2 and SO.sub.2 Cl.sub.2) at temperatures of 25.degree.-200.degree. C. These sulfide ceramics form stoichiometric (single-phase) compounds with sulfides of Ca, Li, Na, K, Al, Mg, Si, Y, La, Ce, Ga, Ba, Zr and Sr and show melting-points that are sufficiently low and have excellent wettability with many metals (Fe, Ni, Mo) to easily form metal/ceramic seals. Ceramic compositions are also formulated to adequately match thermal expansion coefficient of adjacent metal components.

  9. Corrosion resistant ceramic materials

    DOEpatents

    Kaun, T.D.

    1996-07-23

    Ceramic materials are disclosed which exhibit stability in severely-corrosive environments having high alkali-metal activity, high sulfur/sulfide activity and/or molten halides at temperatures of 200--550 C or organic salt (including SO{sub 2} and SO{sub 2}Cl{sub 2}) at temperatures of 25--200 C. These sulfide ceramics form stoichiometric (single-phase) compounds with sulfides of Ca, Li, Na, K, Al, Mg, Si, Y, La, Ce, Ga, Ba, Zr and Sr and show melting-points that are sufficiently low and have excellent wettability with many metals (Fe, Ni, Mo) to easily form metal/ceramic seals. Ceramic compositions are also formulated to adequately match thermal expansion coefficient of adjacent metal components. 1 fig.

  10. Corrosion resistant ceramic materials

    DOEpatents

    Kaun, Thomas D.

    1996-01-01

    Ceramic materials which exhibit stability in severely-corrosive environments having high alkali-metal activity, high sulfur/sulfide activity and/or molten halides at temperatures of 200.degree.-550.degree. C. or organic salt (including SO.sub.2 and SO.sub.2 Cl.sub.2) at temperatures of 25.degree.-200.degree. C. These sulfide ceramics form stoichiometric (single-phase) compounds with sulfides of Ca, Li, Na, K, Al, Mg, Si, Y, La, Ce, Ga, Ba, Zr and Sr and show melting-points that are sufficiently low and have excellent wettability with many metals (Fe, Ni, Mo) to easily form metal/ceramic seals. Ceramic compositions are also formulated to adequately match thermal expansion coefficient of adjacent metal components.

  11. Ceramic fiber filter technology

    SciTech Connect

    Holmes, B.L.; Janney, M.A.

    1996-06-01

    Fibrous filters have been used for centuries to protect individuals from dust, disease, smoke, and other gases or particulates. In the 1970s and 1980s ceramic filters were developed for filtration of hot exhaust gases from diesel engines. Tubular, or candle, filters have been made to remove particles from gases in pressurized fluidized-bed combustion and gasification-combined-cycle power plants. Very efficient filtration is necessary in power plants to protect the turbine blades. The limited lifespan of ceramic candle filters has been a major obstacle in their development. The present work is focused on forming fibrous ceramic filters using a papermaking technique. These filters are highly porous and therefore very lightweight. The papermaking process consists of filtering a slurry of ceramic fibers through a steel screen to form paper. Papermaking and the selection of materials will be discussed, as well as preliminary results describing the geometry of papers and relative strengths.

  12. Super Thin Ceramic Coatings

    NASA Video Gallery

    New technology being developed at NASA's Glenn Research Center creates super thin ceramic coatings on engine components. The Plasma Spray – Physical Vapor Deposition (PS-PVD) rig uses a powerful ...

  13. Advanced Ceramics Property Measurements

    NASA Technical Reports Server (NTRS)

    Salem, Jonathan; Helfinstine, John; Quinn, George; Gonczy, Stephen

    2013-01-01

    Mechanical and physical properties of ceramic bodies can be difficult to measure correctly unless the proper techniques are used. The Advanced Ceramics Committee of ASTM, C-28, has developed dozens of consensus test standards and practices to measure various properties of a ceramic monolith, composite, or coating. The standards give the "what, how, how not, and why" for measurement of many mechanical, physical, thermal, and performance properties. Using these standards will provide accurate, reliable, and complete data for rigorous comparisons with other test results from your test lab, or another. The C-28 Committee has involved academics, producers, and users of ceramics to write and continually update more than 45 standards since the committee's inception in 1986. Included in this poster is a pictogram of the C-28 standards and information on how to obtain individual copies with full details or the complete collection of standards in one volume.

  14. Making Ceramic Cameras

    ERIC Educational Resources Information Center

    Squibb, Matt

    2009-01-01

    This article describes how to make a clay camera. This idea of creating functional cameras from clay allows students to experience ceramics, photography, and painting all in one unit. (Contains 1 resource and 3 online resources.)

  15. OXYGEN TRANSPORT CERAMIC MEMBRANES

    SciTech Connect

    Dr. Sukumar Bandopadhyay; Dr. Nagendra Nagabhushana

    2002-04-01

    This report covers the following tasks: Task 1--Design, fabricate and evaluate ceramic to metal seals based on graded ceramic powder/metal braze joints; Task 2--Evaluate the effect of defect configuration on ceramic membrane conductivity and long term chemical and structural stability; Task 3--Determine materials mechanical properties under conditions of high temperatures and reactive atmospheres; Task 4--Evaluate phase stability and thermal expansion of candidate perovskite membranes and develop techniques to support these materials on porous metal structures; Task 5--Assess the microstructure of membrane materials to evaluate the effects of vacancy-impurity association, defect clusters, and vacancy-dopant association on the membrane performance and stability; and Task 6--Measure kinetics of oxygen uptake and transport in ceramic membrane materials under commercially relevant conditions using isotope labeling techniques.

  16. OXYGEN TRANSPORT CERAMIC MEMBRANES

    SciTech Connect

    Dr. Sukumar Bandopadhyay; Dr. Nagendra Nagabhushana

    2000-07-01

    This is the fourth quarterly report on a new study to develop a ceramic membrane/metal joint. The first experiments using the La-Sr-Fe-O ceramic are reported. Some of the analysis performed on the samples obtained are commented upon. A set of experiments to characterize the mechanical strength and thermal fatigue properties of the joints has been designed and begun. Finite element models of joints used to model residual stresses are described.

  17. Battery utilizing ceramic membranes

    DOEpatents

    Yahnke, Mark S.; Shlomo, Golan; Anderson, Marc A.

    1994-01-01

    A thin film battery is disclosed based on the use of ceramic membrane technology. The battery includes a pair of conductive collectors on which the materials for the anode and the cathode may be spin coated. The separator is formed of a porous metal oxide ceramic membrane impregnated with electrolyte so that electrical separation is maintained while ion mobility is also maintained. The entire battery can be made less than 10 microns thick while generating a potential in the 1 volt range.

  18. Dry mechanochemical synthesis of hydroxyapatites from dicalcium phosphate dihydrate and calcium oxide: a kinetic study.

    PubMed

    El Briak-BenAbdeslam, Hassane; Mochales, Carolina; Ginebra, Maria Pau; Nurit, Josiane; Planell, Josep A; Boudeville, Philippe

    2003-12-01

    Calcium phosphate ceramics have been used successfully as synthetic bone substitutes in orthopedics, dentistry, and maxillofacial surgery. One way of preparing these ceramics is the sintering of a calcium-deficient hydroxyapatite (CDHA), which can be obtained in different ways. Mechanochemistry is one possible means of synthesizing CDHA, with an expected molar calcium-to-phosphate (Ca/P) ratio +/- 0.005. The grinding can be carried out under dry or wet conditions. To optimize the experimental conditions of CDHA preparation by dry mechanosynthesis and for a better understanding of the DCPD/CaO mechanochemical reaction, we performed a kinetic study in which some of the experimental parameters were varied. Carried out with two different vertical rotating ball mills, this kinetic study showed that (1) experiments are reproducible and give as a final product a hydroxyapatite powder, formed of nano-sized crystals of around 20 nm, with a controlled Ca/P ratio; (2) the time for complete disappearance of DCPD and the time for complete reaction are in direct proportion to the mass of the ground powder; but (3) the time for complete disappearance of DCPD is independent of the Ca/P ratio while the time for complete reaction increases exponentially with the Ca/P ratio; and (4) the time for complete disappearance of DCPD corresponds to the time for complete reaction solely for Ca/P = 1.5. These observations suggest a reaction mechanism in two well differentiated stages: (First stage) CaO reacts with DCPD to give first an amorphous calcium phosphate (ACP) with a low Ca/P ratio that transforms into CDHA when its Ca/P ratio reaches 1.5. At the same time, CaO is hydrated into Ca(OH)(2) by the water produced by the reaction. (Second stage) If the Ca/P > 1.5 in the initial mixture, the excess Ca(OH)(2) is added to CDHA 1.5 by reacting with the HPO(4) group of CDHA until its Ca/P ratio reaches the expected value. The slower the reaction, the higher the Ca/P in the initial mixture. PMID

  19. NANOSTRUCTURED CERAMICS AND COMPOSITES FOR REFRACTORY APPLICATIONS IN COAL GASIFICATION

    SciTech Connect

    Paul Brown

    2005-01-31

    A class of ceramics, capable of exhibiting low coefficients of thermal expansion and catalytic properties was investigated. Investigations were directed towards nanoengineering of NZP ceramics and NZP-based composites by chemical means by controlling their compositions and processing variables. NaZr{sub 2}(PO{sub 4}){sub 3} (NZP) was synthesized by combining water-soluble precursors leading to the precipitation of a gel that was dried, calcined, pressed into pellets, then fired at 850 C. Without chemical additives, the resulting ceramic comprised pores ranging in size from approximately 25 to 50 nm and a surface area of about 30m{sup 2}/g. Hydroxyapatite, which has a needle-like morphology, was mechanically mixed with the calcined gel to template NZP crystallization. What resulted was a coarsening of the pore structure and a decrease in surface area. When copper nitrate was added to the solution during synthesis, the resulting ceramic underwent shrinkage upon firing as well as an increase in strength. HAp and copper additions combined resulted in 40% volume shrinkage and a doubling of the tensile strength to 16MPa. A very different type of porosity was achieved when silica was partly substituted for phosphorous in the NZP structure. Na{sub 3}Zr{sub 2}(Si{sub 2}P)O{sub 12} (NASCION) was synthesized in the same manner as NZP, but the fired ceramic possessed a reticulated pore structure comprising large cavities ranging in size from 5 to 50 {micro}m. The NASCION ceramic either shrank or expanded upon firing depending on when the silica was added during synthesis. When the silica precursor (amorphous, precipitated silica) was added before the calcining step, the pressed pellets expanded during firing, whereas they shrank when the silica was added after the gel was calcined. The observed dilation increased with increasing calcining temperature and particle size, up to 26%. The contraction of the ceramic when fired increased with increasing calcining temperature and a

  20. Study of an anisotropic ferrimagnetic bioactive glass ceramic for cancer treatment

    NASA Astrophysics Data System (ADS)

    Shah, Saqlain A.; Hashmi, M. U.; Shamim, A.; Alam, S.

    2010-07-01

    For the hyperthermia therapy of cancer, ferrimagnetic glass ceramics are a potential candidate. Ferrimagnetic zinc-ferrite-containing bioactive glass ceramics were prepared by quenching the glass ceramics from sintering temperature. Then the samples were heated to 600°C and cooled in an aligning magnetic field of 1 Tesla to cause anisotropy. The magnetically aligned samples were compared with non-aligned samples. Vibrating sample magnetometry measurements at 10 kOe showed that the magnetic properties were enhanced by the aligning magnetic field and it led to an enhancement of the magnetic heat generation under a magnetic induction furnace operating at 500 Oe and 400 kHz for 2 min. Data showed that the maximum specific power loss and temperature increase after 2 min were 31.5 W/g and 45°C, respectively, for the aligned sample of maximum zinc-ferrite crystalline content. The glass ceramics were immersed in simulated body fluid for 3 weeks. X-ray diffraction and Fourier transform infrared and atomic absorption spectroscopy results indicated the growth of precipitated hydroxyapatite, suggesting that the ferrimagnetic glass ceramics were bioactive and could bond to living tissues in physiological environment.

  1. Preparation of Porous Hydroxyapatite Tablets and Porous Hydroxyapatite Coatings for Orthopaedic Use

    NASA Astrophysics Data System (ADS)

    Méndez-González, M.

    2004-09-01

    Porous hydroxyapatite tablets and coatings on metal substrates were obtained by the addition of polymeric additives and liofilization. Both tablets and coatings were characterized by scanning electron microscopy and x-ray diffraction. Coatings obtained by plasma spraying also exhibited interconnected porous of 100 μm while coatings obtained by laser ablation did not show any porosity. The diffraction patterns of the deposited HA were similar to that of the powder obtained by the precipitation method suggesting that no significant changes occurred during the coating procedure.

  2. Alumina-based ceramic composite

    DOEpatents

    Alexander, K.B.; Tiegs, T.N.; Becher, P.F.; Waters, S.B.

    1996-07-23

    An improved ceramic composite comprising oxide ceramic particulates, nonoxide ceramic particulates selected from the group consisting of carbides, borides, nitrides of silicon and transition metals and mixtures thereof, and a ductile binder selected from the group consisting of metallic, intermetallic alloys and mixtures thereof is described. The ceramic composite is made by blending powders of the ceramic particulates and the ductile to form a mixture and consolidating the mixture of under conditions of temperature and pressure sufficient to produce a densified ceramic composite. 5 figs.

  3. Ceramic electrolyte coating and methods

    DOEpatents

    Seabaugh, Matthew M.; Swartz, Scott L.; Dawson, William J.; McCormick, Buddy E.

    2007-08-28

    Aqueous coating slurries useful in depositing a dense coating of a ceramic electrolyte material (e.g., yttrium-stabilized zirconia) onto a porous substrate of a ceramic electrode material (e.g., lanthanum strontium manganite or nickel/zirconia) and processes for preparing an aqueous suspension of a ceramic electrolyte material and an aqueous spray coating slurry including a ceramic electrolyte material. The invention also includes processes for depositing an aqueous spray coating slurry including a ceramic electrolyte material onto pre-sintered, partially sintered, and unsintered ceramic substrates and products made by this process.

  4. Clinical application of bio ceramics

    NASA Astrophysics Data System (ADS)

    Anu, Sharma; Gayatri, Sharma

    2016-05-01

    Ceramics are the inorganic crystalline material. These are used in various field such as biomedical, electrical, electronics, aerospace, automotive and optical etc. Bio ceramics are the one of the most active areas of research. Bio ceramics are the ceramics which are biocompatible. The unique properties of bio ceramics make them an attractive option for medical applications and offer some potential advantages over other materials. During the past three decades, a number of major advances have been made in the field of bio ceramics. This review focuses on the use of these materials in variety of clinical scenarios.

  5. Electrokinetic properties of hydroxyapatite under flotation conditions.

    PubMed

    Vucinić, Dusica R; Radulović, Dragan S; Deusić, Slaven D

    2010-03-01

    The effect of calcite supernatant, calcium, and carbonate ions on the hydroxyapatite (HA) zeta potential without and in the presence of sodium oleate (1x10(-4) mol L(-1)) was examined within the pH range from 4 to 12. The interpretation of results was based on the HA surface and oleate solution chemistry, and on some floatability tests. HA, with different positive and negative surface sites formed depending on its solubility and pH, had a negative zeta potential over the whole pH range. This mineral is not naturally floatable (flotation recovery, 5%9.3. The HA surface is less negatively charged in calcite supernatant than in water from pH 6.6 to 9.2 due to the adsorption on HA negative surface active centers ([triple bond]HPO(4)(-) and [triple bond]PO(4)(2-)) of the Ca(2+), and CaOH(+) ions (present in the calcite supernatant), producing more surface sites [triple bond]HPO(4)Ca(+), [triple bond]PO(4)Ca, [triple bond]HPO(4)CaOH, and [triple bond]PO(4)(-) CaOH, and new centers [triple bond]HPO(4)CaHCO(3) and [triple bond]PO(4)(-) CaHCO(3). In the presence of 1x10(-3) mol L(-1) CaCl(2), the HA sample has positive zeta potential, the same as calcite from the same deposit, up to IEP at pH 11.25. Carbonate ions (1x10(-3) mol L(-1) Na(2)CO(3)) do not affect the HA zeta potential. However, a possible process can be the ion-exchange reaction between

  6. Osteoinductive hydroxyapatite-coated titanium implants.

    PubMed

    Ripamonti, Ugo; Roden, Laura C; Renton, Louise F

    2012-05-01

    Previous studies have shown that heterotopic induction of bone formation by calcium phosphate-based macroporous constructs is set into motion by the geometry of the implanted substrata, i.e. a sequence of repetitive concavities assembled within the macroporous spaces. The aim of this study was to construct osteoinductive titanium implants that per se, and without the exogenous application of the osteogenic soluble molecular signals of the transforming growth factor-β supergene family, would initiate the induction of bone formation. To generate intrinsically osteoinductive titanium implants for translation in clinical contexts, titanium grade Ti-6A1-4V cylinders of 15 mm in length and 3.85 mm in diameter, with or without concavities, were plasma sprayed with crystalline hydroxyapatite resulting in a uniform layer of 30 μm in thickness. Before coating, experimental titanium implants were prepared with a sequence of 36 repetitive concavities 1600 μm in diameter and 800 μm in depth, spaced a distance of 1000 μm apart. Mandibular molars and premolars were extracted to prepare edentulous mandibular ridges for later implantation. Planar and geometric hydroxyapatite-coated titanium constructs were implanted in the left and right edentulized hemi-mandibles, respectively, after a healing period of 7-8 months, 3 per hemi-mandible. Three planar and three geometric implants were implanted in the left and right tibiae, respectively; additionally, planar and geometric constructs were also inserted in the rectus abdominis muscle. Six animals were euthanized at 30 and 90 days after implantation; one animal had to be euthanized 5 days after surgery and the remaining animal was euthanized 31 months after implantation. Undecalcified longitudinal sections were precision-sawed, ground and polished to 40-60 μm; all sections were stained with a modified Goldner's trichrome. Undecalcified specimen block preparation was performed using the EXAKT precision cutting and grinding system

  7. Ectopic bone formation cannot occur by hydroxyapatite/β-tricalcium phosphate bioceramics in green fluorescent protein chimeric mice

    NASA Astrophysics Data System (ADS)

    Cheng, Lijia; Duan, Xin; Xiang, Zhou; Shi, Yujun; Lu, Xiaofeng; Ye, Feng; Bu, Hong

    2012-12-01

    Many studies have shown that calcium phosphate ceramics (CP) have osteoconductive and osteoinductive properties; however, the exact mechanism of bone induction has not yet been reported. This study was performed to investigate if destroying immunological function will influence osteogenesis, to explain the mechanism which is unclear. In this study, twenty C57BL/6 mice were divided into two groups (n = 10), in group 1, a hydroxyapatite/β-tricalcium phosphate (HA/β-TCP) ceramic was implanted into both the left and right leg muscles of each mouse; in group 2, ten mice experienced lethal irradiation, then were injected bone marrow (BM) cells from green fluorescent protein (GFP) transgenic mice by tail veil, after bone marrow transplantation (BMT), heart, liver, spleen, lung, kidney, and muscle were harvested for biological analysis, after the GFP chimera model was established successfully, the same HA/β-TCP ceramic was implanted into both leg muscles of each mouse immediately after irradiation. 45 and 90 days after implantation, the ceramics of the two groups were harvested to perform with hematoxylin and eosin (HE) and immunohistochemistry (IHC) staining; the results showed that there was no bone formation in group 2, while new bone tissues were detected in group 1. Our findings suggest that the BM cell from GFP transgenic mice is a good biomarker and it could set a good platform for chimera model; it also shows that BM cell is one of cell resources of bone induction, and destruction of immune function will impede osteoinduction by CP. Overall, our results may shed light on clear mechanism study of bone induction in the future.

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

    NASA Astrophysics Data System (ADS)

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

    2015-11-01

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

  9. Cobalt doped proangiogenic hydroxyapatite for bone tissue engineering application.

    PubMed

    Kulanthaivel, Senthilguru; Roy, Bibhas; Agarwal, Tarun; Giri, Supratim; Pramanik, Krishna; Pal, Kunal; Ray, Sirsendu S; Maiti, Tapas K; Banerjee, Indranil

    2016-01-01

    The present study delineates the synthesis and characterization of cobalt doped proangiogenic-osteogenic hydroxyapatite. Hydroxyapatite samples, doped with varying concentrations of bivalent cobalt (Co(2+)) were prepared by the ammoniacal precipitation method and the extent of doping was measured by ICP-OES. The crystalline structure of the doped hydroxyapatite samples was confirmed by XRD and FTIR studies. Analysis pertaining to the effect of doped hydroxyapatite on cell cycle progression and proliferation of MG-63 cells revealed that the doping of cobalt supported the cell viability and proliferation up to a threshold limit. Furthermore, such level of doping also induced differentiation of the bone cells, which was evident from the higher expression of differentiation markers (Runx2 and Osterix) and better nodule formation (SEM study). Western blot analysis in conjugation with ELISA study confirmed that the doped HAp samples significantly increased the expression of HIF-1α and VEGF in MG-63 cells. The analysis described here confirms the proangiogenic-osteogenic properties of the cobalt doped hydroxyapatite and indicates its potential application in bone tissue engineering. PMID:26478356

  10. [Ceramic-on-ceramic bearings in total hip arthroplasty (THA)].

    PubMed

    Sentürk, U; Perka, C

    2015-04-01

    The main reason for total hip arthroplasty (THA) revision is the wear-related aseptic loosening. Younger and active patients after total joint replacement create high demands, in particular, on the bearings. The progress, especially for alumina ceramic-on-ceramic bearings and mixed ceramics have solved many problems of the past and lead to good in vitro results. Modern ceramics (alumina or mixed ceramics containing alumina) are extremely hard, scratch-resistant, biocompatible, offer a low coefficient of friction, superior lubrication and have the lowest wear rates in comparison to all other bearings in THA. The disadvantage of ceramic is the risk of material failure, i.e., of ceramic fracture. The new generation of mixed ceramics (delta ceramic), has reduced the risk of head fractures to 0.03-0.05 %, but the risk for liner fractures remains unchanged at about 0.02 %. Assuming a non-impinging component implantation, ceramic-on-ceramic bearings have substantial advantages over all other bearings in THA. Due to the superior hardness, ceramic bearings produce less third body wear and are virtually impervious to damage from instruments during the implantation process. A specific complication for ceramic-on-ceramic bearings is "squeaking". The high rate of reported squeaking (0.45 to 10.7 %) highlights the importance of precise implant positioning and the stem and patient selection. With precise implant positioning this problem is rare with many implant designs and without clinical relevance. The improved tribology and the presumable resulting implant longevity make ceramic-on-ceramic the bearing of choice for young and active patients. PMID:25874400

  11. Structural and Magnetic Studies on Nano-crystalline Biocompatible Glass/Glass-ceramic

    NASA Astrophysics Data System (ADS)

    Kothiyal, G. P.; Sharma, K.; Dixit, A.; Srinivasan, A.

    2010-12-01

    Ferrimagnetic glass-ceramics have been derived from bulk CaO-P2O5-SiO2-Fe2O3 glass system containing different additives like MgO, ZnO etc. by controlled crystallization. Phase formation and magnetic behaviour of glass-ceramics samples have been studied using XRD and SQUID magnetometer. The microstructure as seen by scanning electron microscopy exhibits nano sized particles. Nanocrystalline hematite and magnetite along with bone mineral phases constitute the major crystalline phases. Saturation magnetization increases with increase in amount of iron oxide since the volume fraction of magnetite has also increased. Addition of ZnO leads to increase in the saturation magnetization. In vitro response in simulated body fluid shows the formation of hydroxyapatite like layer implying the bioactive nature of the samples.

  12. Piezoelectric Ceramics and Their Applications

    ERIC Educational Resources Information Center

    Flinn, I.

    1975-01-01

    Describes the piezoelectric effect in ceramics and presents a quantitative representation of this effect. Explains the processes involved in the manufacture of piezoelectric ceramics, the materials used, and the situations in which they are applied. (GS)

  13. Fundamental tribological properties of ceramics

    NASA Technical Reports Server (NTRS)

    Buckley, D. H.; Miyoshi, K.

    1985-01-01

    When a ceramic is brought into contact with itself, another ceramic, or a metal, strong bond forces can develop between the materials. Adhesion between a ceramic and itself or another solid are discussed from a theoretical consideration of the nature of the surfaces and experimentally by relating bond forces to the interface resulting from solid state contact. Elastic, plastic, and fracture behavior of ceramics in solid-state contact are discussed as they relate to friction and wear. The contact load necessary to initiate fracture in ceramics is shown to be appreciably reduced with tangential motion. Both friction and wear of ceramics are anisotropic and relate to crystal structure as with metals. Both free energy of oxide formation and the d valence bond character of metals are related to the friction and wear characteristics for metals in contact with ceramics. Lubrication is found to increase the critical load necessary to initiate fracture of ceramics with sliding or rubbing contact.

  14. Microstructure and properties of ceramics

    NASA Technical Reports Server (NTRS)

    Hamano, K.

    1984-01-01

    The history of research into the microstructure and properties of ceramic ware is discussed; methods of producing ceramics with particular characteristics are investigated. Bubbles, sintering, cracks, and electron microscopy are discussed.

  15. Nano-Hydroxyapatite Thick Film Gas Sensors

    NASA Astrophysics Data System (ADS)

    Khairnar, Rajendra S.; Mene, Ravindra U.; Munde, Shivaji G.; Mahabole, Megha P.

    2011-12-01

    In the present work pure and metal ions (Co and Fe) doped hydroxyapatite (HAp) thick films have been successfully utilized to improve the structural, morphological and gas sensing properties. Nanocrystalline HAp powder is synthesized by wet chemical precipitation route, and ion exchange process is employed for addition of Co and Fe ions in HAp matrix. Moreover, swift heavy ion irradiation (SHI) technique is used to modify the surface of pure and metal ion exchanged HAp with various ion fluence. The structural investigation of pure and metal ion exchanged HAp thick films are carried out using X-ray diffraction and the presence of functional group is observed by means FTIR spectroscopy. Furthermore, surface morphology is visualized by means of SEM and AFM analysis. CO gas sensing study is carried out for, pure and metal ions doped, HAp thick films with detail investigation on operating temperature, response/recovery time and gas uptake capacity. The surface modifications of sensor matrix by SHI enhance the gas response, response/recovery and gas uptake capacity. The significant observation is here to note that, addition of Co and Fe in HAp matrix and surface modification by SHI improves the sensing properties of HAp films drastically resulting in gas sensing at relatively lower temperatures.

  16. Dual functional selenium-substituted hydroxyapatite.

    PubMed

    Wang, Yanhua; Ma, Jun; Zhou, Lei; Chen, Jin; Liu, Yonghui; Qiu, Zhiye; Zhang, Shengmin

    2012-06-01

    Hydroxyapatite (HA) doped with trace elements has attracted much attention recently owing to its excellent biological functions. Herein, we use a facile co-precipitation method to incorporate selenium into HA by adding sodium selenite during synthesis. The obtained selenium-substituted HA products are needle-like nanoparticles which have  size and crystallinity that are similar to those of the pure HA nanoparticles (HANs) when the selenium content is low. HANs are found to have the ability to induce the apoptosis of osteosarcoma cells, and the anti-tumour effects are enhanced after incorporation of selenium. Meanwhile, the nanoparticles can also support the growth of bone marrow stem cells. Furthermore, the flow cytometric results indicate that the apoptosis induction of osteosarcoma cells is caused by the increased reactive oxygen species and decreased mitochondrial membrane potential. These results show that the selenium-substituted HANs are potentially promising bone graft materials in osteosarcoma treatment due to their dual functions of supporting normal cell growth and inducing tumour cell apoptosis. PMID:23741613

  17. Nano-Hydroxyapatite Thick Film Gas Sensors

    SciTech Connect

    Khairnar, Rajendra S.; Mene, Ravindra U.; Munde, Shivaji G.; Mahabole, Megha P.

    2011-12-10

    In the present work pure and metal ions (Co and Fe) doped hydroxyapatite (HAp) thick films have been successfully utilized to improve the structural, morphological and gas sensing properties. Nanocrystalline HAp powder is synthesized by wet chemical precipitation route, and ion exchange process is employed for addition of Co and Fe ions in HAp matrix. Moreover, swift heavy ion irradiation (SHI) technique is used to modify the surface of pure and metal ion exchanged HAp with various ion fluence. The structural investigation of pure and metal ion exchanged HAp thick films are carried out using X-ray diffraction and the presence of functional group is observed by means FTIR spectroscopy. Furthermore, surface morphology is visualized by means of SEM and AFM analysis. CO gas sensing study is carried out for, pure and metal ions doped, HAp thick films with detail investigation on operating temperature, response/recovery time and gas uptake capacity. The surface modifications of sensor matrix by SHI enhance the gas response, response/recovery and gas uptake capacity. The significant observation is here to note that, addition of Co and Fe in HAp matrix and surface modification by SHI improves the sensing properties of HAp films drastically resulting in gas sensing at relatively lower temperatures.

  18. Dip coated silicon-substituted hydroxyapatite films.

    PubMed

    Hijón, Natalia; Victoria Cabañas, M; Peña, Juan; Vallet-Regí, María

    2006-09-01

    Silicon-substituted hydroxyapatites have been deposited onto Ti6Al4V substrates by sol-gel technology. The Ca(10)(PO(4))(6-x-y)(SiO(4))(x)(CO(3))(y)(OH)(2-x+y) coatings obtained, with silicon contents up to x=1 (2.8 wt.%), show a homogeneous and crack-free surface composed of particles smaller than 20 nm. The silicon enters into the apatite structure in the form of SiO(4)(4-) groups that partially substitute the PO(4)(3-) groups. The Si content and the Ca/P molar ratio of the coatings agree with those originally introduced in the sols. Layers with thicknesses around 600 nm show adhesion strengths superior to 20 MPa as determined by a pull-out test. The formation of an apatite layer onto these coatings after immersion in a simulated body fluid is enhanced by the presence of silicon. PMID:16828579

  19. Chemical characterization of some substituted hydroxyapatites

    PubMed Central

    2011-01-01

    Synthetic multi-substituted hydroxyapatite nano powders containing silicon and or carbonate prepared by a wet chemical method. The process parameters are set up to allow the simultaneous substitution of carbonate and silicon ions in the place of phosphorus. The chemical and structural characterizations of the prepared powders are determined with the aid of; XRF, ICP, XRD and FTIR. The results show that, the ion substitution in the crystal lattice of HA caused a change in the unit cell dimensions and affected the degree of crystallization of the produced powders. The apatite formation abilityy of the prepared discs from the synthesized powders is determined by immersing in SBF solution for different periods. The degree of ion release was determined in the obtained solutions. The examined surface of the immersed discs under SEM and analyzed by CDS showed a more dense HA layer than those of un-substituted ones. The HA with the substituted silicon and carbonate ions, showed the highest solubility with greater rate of ion release, compared with carbonate-free powder. All prepared powders took sodium ion from the SBF solution during immersion, which was not recorded before. PMID:22122971

  20. Elastin-like polypeptide based hydroxyapatite bionanocomposites.

    PubMed

    Wang, Eddie; Lee, Sang-Hyuk; Lee, Seung-Wuk

    2011-03-14

    In nature, organic matrix macromolecules play a critical role in enhancing the mechanical properties of biomineralized composites such as bone and teeth. Designing artificial matrix analogues is promising but challenging because relatively little is known about how natural matrix components function. Therefore, in lieu of using natural components, we created biomimetic matrices using genetically engineered elastin-like polypeptides (ELPs) and then used them to construct mechanically robust ELP-hydroxyapatite (HAP) composites. ELPs were engineered with well-defined backbone charge distributions by periodic incorporation of negative, positive, or neutral side chains or with HAP-binding octaglutamic acid motifs at one or both protein termini. ELPs exhibited sequence-specific capacities to interact with ions, bind HAP, and disperse HAP nanoparticles. HAP-binding ELPs were incorporated into calcium phosphate cements, resulting in materials with improved mechanical strength, injectability, and antiwashout properties. The results demonstrate that rational design of genetically engineered polymers is a powerful system for determining sequence-property relationships and for improving the properties of organic-inorganic composites. Our approach may be used to further develop novel, multifunctional bone cements and expanded to the design of other advanced composites. PMID:21218767

  1. Synthesis of carbonated hydroxyapatite nanospheres through nanoemulsion.

    PubMed

    Zhou, W Y; Wang, M; Cheung, W L; Guo, B C; Jia, D M

    2008-01-01

    This study investigated the nanoemulsion technique as a means to synthesize carbonated hydroxyapatite (CHAp) nanospheres which could be used to produce composite tissue engineering scaffolds. CHAp nanospheres were successfully synthesized by mixing an acetone solution of Ca(NO(3))(2).4H(2)O with an aqueous solution of (NH(4))(2)HPO(4) and NH(4)HCO(3). Four reaction temperatures, namely, 4, 25, 37 and 55 degrees C, were investigated and no surfactant was added in all nanoemulsion processes. Wet slurries of CHAp from the nanoemulsions were freeze-dried to obtain dry powders. X-ray diffraction (XRD) results showed that the as-synthesized CHAp nanoparticles were mainly in an amorphous state. After calcination at 900 degrees C, the apatite became well crystallized. Fourier transform infrared (FTIR) spectroscopy showed that the CHAp was B-type substitution. Both scanning electron microscopy (SEM) and transmission electron microscopy (TEM) revealed that the CHAp particles were spherical in shape and that their sizes were in the nanometer range. The successful synthesis of CHAp nanospheres is a critical step forward in our efforts to fabricate bone tissue engineering scaffolds using the selective laser sintering technology. PMID:17577636

  2. Osteoclasts in the interface with electrospun hydroxyapatite.

    PubMed

    Pasuri, Jenni; Holopainen, Jani; Kokkonen, Hanna; Persson, Maria; Kauppinen, Kyösti; Lehenkari, Petri; Santala, Eero; Ritala, Mikko; Tuukkanen, Juha

    2015-11-01

    Electrospinning is a method to produce lightweight, resorbable and bioinspired scaffolds for tissue engineering. Here we investigated the influence of electrospun hydroxyapatite fibers (HA) on macrophages and osteoclasts. A mouse macrophage cell line (RAW 264.7) and human bone marrow derived primary osteoclasts (hOC) were cultured with electrospun HA fibers embedded in Matrigel. Cell morphology and the secretion of pro-inflammatory cytokines (IL-6 and TNF-α) were analyzed using macrophages. Both fluorescent microscopy and scanning electron microscopy indicated that the cell morphology differed on the various materials (HA fibers on Matrigel, pure Matrigel and a glass control). Control macrophages were activated with bacterial lipopolysaccharide (LPS) but electrospun HA did not provoke an inflammatory response. Cytokine secretion detected with enzyme-linked immunosorbent assay (ELISA) also supported this observation. LPS, but not HA fibers, stimulated TNF-α and IL-6 secretion by macrophages at the 2 day time point. After 4 days in culture there was an increasing trend in cytokine secretion in the HA fiber samples. Human bone marrow myeloid precursor cells were able to fuse and differentiate on the fibrous mineral scaffold to form functional multinuclear osteoclasts that were able to resorb the HA nanofibers. This indicates that osteoclasts do not necessarily need a continuous bone surface but osteoclast ruffled border membranes can form a resorption interface with a fibrous mineral scaffold. PMID:26342323

  3. Ceramic microstructure and adhesion

    NASA Technical Reports Server (NTRS)

    Buckley, D. H.

    1984-01-01

    When a ceramic is brought into contact with a ceramic, a polymer, or a metal, strong bond forces can develop between the materials. The bonding forces will depend upon the state of the surfaces, cleanliness and the fundamental properties of the two solids, both surface and bulk. Adhesion between a ceramic and another solid are discussed from a theoretical consideration of the nature of the surfaces and experimentally by relating bond forces to interface resulting from solid state contact. Surface properties of ceramics correlated with adhesion include, orientation, reconstruction and diffusion as well as the chemistry of the surface specie. Where a ceramic is in contact with a metal their interactive chemistry and bond strength is considered. Bulk properties examined include elastic and plastic behavior in the surficial regions, cohesive binding energies, crystal structures and crystallographic orientation. Materials examined with respect to interfacial adhesive interactions include silicon carbide, nickel zinc ferrite, manganese zinc ferrite, and aluminum oxide. The surfaces of the contacting solids are studied both in the atomic or molecularly clean state and in the presence of selected surface contaminants.

  4. Ceramic impregnated superabrasives

    DOEpatents

    Radtke, Robert P.; Sherman, Andrew

    2009-02-10

    A superabrasive fracture resistant compact is formed by depositing successive layers of ceramic throughout the network of open pores in a thermally stable self-bonded polycrystalline diamond or cubic boron nitride preform. The void volume in the preform is from approximately 2 to 10 percent of the volume of the preform, and the average pore size is below approximately 3000 nanometers. The preform is evacuated and infiltrated under at least about 1500 pounds per square inch pressure with a liquid pre-ceramic polymerizable precursor. The precursor is infiltrated into the preform at or below the boiling point of the precursor. The precursor is polymerized into a solid phase material. The excess is removed from the outside of the preform, and the polymer is pyrolized to form a ceramic. The process is repeated at least once more so as to achieve upwards of 90 percent filling of the original void volume. When the remaining void volume drops below about 1 percent the physical properties of the compact, such as fracture resistance, improve substantially. Multiple infiltration cycles result in the deposition of sufficient ceramic to reduce the void volume to below 0.5 percent. The fracture resistance of the compacts in which the pores are lined with formed in situ ceramic is generally at least one and one-half times that of the starting preforms.

  5. Ceramic combustor mounting

    DOEpatents

    Hoffman, Melvin G.; Janneck, Frank W.

    1982-01-01

    A combustor for a gas turbine engine includes a metal engine block including a wall portion defining a housing for a combustor having ceramic liner components. A ceramic outlet duct is supported by a compliant seal on the metal block and a reaction chamber liner is stacked thereon and partly closed at one end by a ceramic bypass swirl plate which is spring loaded by a plurality of circumferentially spaced, spring loaded guide rods and wherein each of the guide rods has one end thereof directed exteriorly of a metal cover plate on the engine block to react against externally located biasing springs cooled by ambient air and wherein the rod spring support arrangement maintains the stacked ceramic components together so that a normal force is maintained on the seal between the outlet duct and the engine block under all operating conditions. The support arrangement also is operative to accommodate a substantial difference in thermal expansion between the ceramic liner components of the combustor and the metal material of the engine block.

  6. FATIGUE OF DENTAL CERAMICS

    PubMed Central

    Zhang, Yu; Sailer, Irena; Lawn, Brian R

    2013-01-01

    Objectives Clinical data on survival rates reveal that all-ceramic dental prostheses are susceptible to fracture from repetitive occlusal loading. The objective of this review is to examine the underlying mechanisms of fatigue in current and future dental ceramics. Data/sources The nature of various fatigue modes is elucidated using fracture test data on ceramic layer specimens from the dental and biomechanics literature. Conclusions Failure modes can change over a lifetime, depending on restoration geometry, loading conditions and material properties. Modes that operate in single-cycle loading may be dominated by alternative modes in multi-cycle loading. While post-mortem examination of failed prostheses can determine the sources of certain fractures, the evolution of these fractures en route to failure remains poorly understood. Whereas it is commonly held that loss of load-bearing capacity of dental ceramics in repetitive loading is attributable to chemically-assisted 'slow crack growth' in the presence of water, we demonstrate the existence of more deleterious fatigue mechanisms, mechanical rather than chemical in nature. Neglecting to account for mechanical fatigue can lead to gross overestimates in predicted survival rates. Clinical significance Strategies for prolonging the clinical lifetimes of ceramic restorations are proposed based on a crack-containment philosophy. PMID:24135295

  7. OXYGEN TRANSPORT CERAMIC MEMBRANES

    SciTech Connect

    Dr. Sukumar Bandopadhyay; Dr. Nagendra Nagabhushana

    2000-10-01

    This is the third quarterly report on oxygen Transport Ceramic Membranes. In the following, the report describes the progress made by our university partners in Tasks 1 through 6, experimental apparatus that was designed and built for various tasks of this project, thermodynamic calculations, where applicable and work planned for the future. (Task 1) Design, fabricate and evaluate ceramic to metal seals based on graded ceramic powder/metal braze joints. (Task 2) Evaluate the effect of defect configuration on ceramic membrane conductivity and long term chemical and structural stability. (Task 3) Determine materials mechanical properties under conditions of high temperatures and reactive atmospheres. (Task 4) Evaluate phase stability and thermal expansion of candidate perovskite membranes and develop techniques to support these materials on porous metal structures. (Task 5) Assess the microstructure of membrane materials to evaluate the effects of vacancy-impurity association, defect clusters, and vacancy-dopant association on the membrane performance and stability. (Task 6) Measure kinetics of oxygen uptake and transport in ceramic membrane materials under commercially relevant conditions using isotope labeling techniques.

  8. Microsphere-based scaffolds encapsulating tricalcium phosphate and hydroxyapatite for bone regeneration.

    PubMed

    Gupta, Vineet; Lyne, Dina V; Barragan, Marilyn; Berkland, Cory J; Detamore, Michael S

    2016-07-01

    Bioceramic mixtures of tricalcium phosphate (TCP) and hydroxyapatite (HAp) are widely used for bone regeneration because of their excellent cytocompatibility, osteoconduction, and osteoinduction. Therefore, we hypothesized that incorporation of a mixture of TCP and HAp in microsphere-based scaffolds would enhance osteogenesis of rat bone marrow stromal cells (rBMSCs) compared to a positive control of scaffolds with encapsulated bone-morphogenic protein-2 (BMP-2). Poly(D,L-lactic-co-glycolic acid) (PLGA) microsphere-based scaffolds encapsulating TCP and HAp mixtures in two different ratios (7:3 and 1:1) were fabricated with the same net ceramic content (30 wt%) to evaluate how incorporation of these ceramic mixtures would affect the osteogenesis in rBMSCs. Encapsulation of TCP/HAp mixtures impacted microsphere morphologies and the compressive moduli of the scaffolds. Additionally, TCP/HAp mixtures enhanced the end-point secretion of extracellular matrix components relevant to bone tissue compared to the "blank" (PLGA-only) microsphere-based scaffolds as evidenced by the biochemical, gene expression, histology, and immunohistochemical characterization. Moreover, the TCP/HAp mixture groups even surpassed the BMP-2 positive control group in some instances in terms of matrix synthesis and gene expression. Lastly, gene expression data suggested that the rBMSCs responded differently to different TCP/HAp ratios presented to them. Altogether, it can be concluded that TCP/HAp mixtures stimulated the differentiation of rBMSCs toward an osteoblastic phenotype, and therefore may be beneficial in gradient microsphere-based scaffolds for osteochondral regeneration. PMID:27272903

  9. An Investigation of Siloxane Cross-linked Hydroxyapatite-Gelatin/Copolymer Composites for Potential Orthopedic Applications().

    PubMed

    Dyke, Jason Christopher; Knight, Kelly Jane; Zhou, Huaxing; Chiu, Chi-Kai; Ko, Ching-Chang; You, Wei

    2012-01-01

    Causes of bone deficiency are numerous, but biomimetic alloplastic grafts provide an alternative to repair tissue naturally. Previously, a hydroxyapatite-gelatin modified siloxane (HAp-Gemosil) composite was prepared by cross-linking (N, N'-bis[(3-trimethoxysilyl)propyl]ethylene diamine (enTMOS) around the HAp-Gel nanocomposite particles, to mimic the natural composition and properties of bone. However, the tensile strength remained too low for many orthopedic applications. It was hypothesized that incorporating a polymer chain into the composite could help improve long range interaction. Furthermore, designing this polymer to interact with the enTMOS siloxane cross-linked matrix would provide improved adhesion between the polymer and the ceramic composite, and improve mechanical properties. To this end, copolymers of L-Lactide (LLA), and a novel alkyne derivatized trimethylene carbonate, propargyl carbonate (PC), were synthesized. Incorporation of PC during copolymerization affects properties of copolymers such as molecular weight, T(g), and % PC incorporation. More importantly, PC monomers bear a synthetic handle, allowing copolymers to undergo post-polymerization functionalization with graft monomers to specifically tailor the properties of the final composite. For our investigation, P(LLA-co-PC) copolymers were functionalized by an azido-silane (AS) via copper catalyzed azide-alkyne cycloaddition (CuAAC) through terminal alkyne on PC monomers. The new functionalized polymer, P(LLA-co-PC)(AS) was blended with HAp-Gemosil, with the azido-silane linking the copolymer to the silsesquioxane matrix within the final composite.These HAp-Gemosil/P(LLA-co-PC)(AS) composites were subjected to mechanical and biological testing, and the results were compared with those from the HAp-Gemosil composites. This study revealed that incorporating a cross-linkable polymer served to increase the flexural strength of the composite by 50%, while maintaining the biocompatibility of HAp

  10. An Investigation of Siloxane Cross-linked Hydroxyapatite-Gelatin/Copolymer Composites for Potential Orthopedic Applications†

    PubMed Central

    Dyke, Jason Christopher; Knight, Kelly Jane; Zhou, Huaxing; Chiu, Chi-Kai; Ko, Ching-Chang; You, Wei

    2012-01-01

    Causes of bone deficiency are numerous, but biomimetic alloplastic grafts provide an alternative to repair tissue naturally. Previously, a hydroxyapatite-gelatin modified siloxane (HAp-Gemosil) composite was prepared by cross-linking (N, N′-bis[(3-trimethoxysilyl)propyl]ethylene diamine (enTMOS) around the HAp-Gel nanocomposite particles, to mimic the natural composition and properties of bone. However, the tensile strength remained too low for many orthopedic applications. It was hypothesized that incorporating a polymer chain into the composite could help improve long range interaction. Furthermore, designing this polymer to interact with the enTMOS siloxane cross-linked matrix would provide improved adhesion between the polymer and the ceramic composite, and improve mechanical properties. To this end, copolymers of L-Lactide (LLA), and a novel alkyne derivatized trimethylene carbonate, propargyl carbonate (PC), were synthesized. Incorporation of PC during copolymerization affects properties of copolymers such as molecular weight, Tg, and % PC incorporation. More importantly, PC monomers bear a synthetic handle, allowing copolymers to undergo post-polymerization functionalization with graft monomers to specifically tailor the properties of the final composite. For our investigation, P(LLA-co-PC) copolymers were functionalized by an azido-silane (AS) via copper catalyzed azide-alkyne cycloaddition (CuAAC) through terminal alkyne on PC monomers. The new functionalized polymer, P(LLA-co-PC)(AS) was blended with HAp-Gemosil, with the azido-silane linking the copolymer to the silsesquioxane matrix within the final composite. These HAp-Gemosil/P(LLA-co-PC)(AS) composites were subjected to mechanical and biological testing, and the results were compared with those from the HAp-Gemosil composites. This study revealed that incorporating a cross-linkable polymer served to increase the flexural strength of the composite by 50%, while maintaining the biocompatibility of

  11. Study of thermal effects of silicate-containing hydroxyapatites

    NASA Astrophysics Data System (ADS)

    Golovanova, O. A.; Zaits, A. V.; Berdinskaya, N. V.; Mylnikova, T. S.

    2016-02-01

    The possibility of modifications of hydroxyapatite silicate ions, from the extracellular fluid prototype solution under near-physiological conditions has been studied. Formation of silicon-structured hydroxyapatite with different extent of substitution of phosphate groups in the silicate group has been established through chemical and X-ray diffraction analyses, FTIR spectroscopy and optical microscopy. The results obtained are in agreement and suggest the possibility of substitution of phosphate groups for silicate groups in the hydroxyapatite structure when introducing different sources of silica, tetraethoxysilane and sodium silicate, in the reaction mixture. Growth in the amount of silicon in Si-HA results in the increase in the thermal stability of the samples. The greatest mass loss occurs at temperatures in the range of 25-400 0C that is caused by the removal of the crystallization and adsorption water and volatile impurities. It is shown that the modified apatites are of imperfect structure and crystallize in a nanocrystalline state.

  12. Recent Advances in Hydroxyapatite Scaffolds Containing Mesenchymal Stem Cells

    PubMed Central

    Michel, John; Penna, Matthew; Kochen, Juan; Cheung, Herman

    2015-01-01

    Modern day tissue engineering and cellular therapies have gravitated toward using stem cells with scaffolds as a dynamic modality to aid in differentiation and tissue regeneration. Mesenchymal stem cells (MSCs) are one of the most studied stem cells used in combination with scaffolds. These cells differentiate along the osteogenic lineage when seeded on hydroxyapatite containing scaffolds and can be used as a therapeutic option to regenerate various tissues. In recent years, the combination of hydroxyapatite and natural or synthetic polymers has been studied extensively. Due to the interest in these scaffolds, this review will cover the wide range of hydroxyapatite containing scaffolds used with MSCs for in vitro and in vivo experiments. Further, in order to maintain a progressive scope of the field this review article will only focus on literature utilizing adult human derived MSCs (hMSCs) published in the last three years. PMID:26106425

  13. Synthesis and Antimicrobial Activity of Silver-Doped Hydroxyapatite Nanoparticles

    PubMed Central

    Ciobanu, Carmen Steluta; Iconaru, Simona Liliana; Chifiriuc, Mariana Carmen; Costescu, Adrian; Le Coustumer, Philippe; Predoi, Daniela

    2013-01-01

    The synthesis of nanosized particles of Ag-doped hydroxyapatite with antibacterial properties is of great interest for the development of new biomedical applications. The aim of this study was the evaluation of Ca10−xAgx(PO4)6(OH)2 nanoparticles (Ag:HAp-NPs) for their antibacterial and antifungal activity. Resistance to antimicrobial agents by pathogenic bacteria has emerged in the recent years and became a major health problem. Here, we report a method for synthesizing Ag doped nanocrystalline hydroxyapatite. A silver-doped nanocrystalline hydroxyapatite was synthesized at 100°C in deionised water. Also, in this paper Ag:HAp-NPs are evaluated for their antimicrobial activity against Gram-positive and Gram-negative bacteria and fungal strains. The specific antimicrobial activity revealed by the qualitative assay is demonstrating that our compounds are interacting differently with the microbial targets, probably due to the differences in the microbial wall structures. PMID:23509801

  14. Investigations on hydroxyapatite powder obtained by wet precipitation

    NASA Astrophysics Data System (ADS)

    Poinescu, Aurora Anca; Ion, Rodica Mariana; van Staden, Raluca-Ioana; van Staden, Jacobus Frederick; Ghiurea, Marius

    2010-11-01

    It is well-known that hydroxyapatite have multiple applications in tissue engineering due to compositional similarities with bone tissue. In this work, hydroxyapatite powders obtained by modified chemical precipitation route, has been investigated by AMF and SEM analysis grain size, X-ray diffraction and infra-red spectroscopy. The particle size of hydroxyapatite was observed to be very fine, uniform, around 50 -60 nm. SEM observation of the HA coatings showed the presence of nano-sized needles, with a significant level of agglomeration. The infrared analysis show the characteristic peaks of absorbed water, hydroxyl, phosphate and carbonate species. The XRD pattern clearly indicated the crystallites responsible for the Bragg reflection of the (002) and (003) planes are useful for size determination by Sherrer relationship (around 68 nm).

  15. Lightweight ceramic insulation and method

    NASA Technical Reports Server (NTRS)

    Green, David J. (Inventor)

    1990-01-01

    A process is disclosed for manufacturing a low density ceramic powder which can be formed to make a lightweight material for insulation or other construction. The ceramic product made from the process has a final density of less than 25 to about 1 percent of the theoretical weight of the ceramic powder. The ceramic product is lightweight and can be made to withstand high temperatures greater than 1400 C.

  16. Nondestructive evaluation of advanced ceramics

    NASA Technical Reports Server (NTRS)

    Klima, Stanley J.; Kautz, Harold E.

    1988-01-01

    A review is presented of Lewis Research Center efforts to develop nondestructive evaluation techniques for characterizing advanced ceramic materials. Various approaches involved the use of analytical ultrasonics to characterize monolythic ceramic microstructures, acousto-ultrasonics for characterizing ceramic matrix composites, damage monitoring in impact specimens by microfocus X-ray radiography and scanning ultrasonics, and high resolution computed X-ray tomography to identify structural features in fiber reinforced ceramics.

  17. Ceramic Automotive Stirling Engine Program

    SciTech Connect

    Not Available

    1986-08-01

    The Ceramic Automotive Stirling Engine Program evaluated the application of advanced ceramic materials to an automotive Stirling engine. The objective of the program was to evaluate the technical feasibility of utilizing advanced ceramics to increase peak engine operating temperature, and to evaluate the performance benefits of such an increase. Manufacturing cost estimates were also developed for various ceramic engine components and compared with conventional metallic engine component costs.

  18. Ceramic automotive Stirling engine program

    NASA Technical Reports Server (NTRS)

    1986-01-01

    The Ceramic Automotive Stirling Engine Program evaluated the application of advanced ceramic materials to an automotive Stirling engine. The objective of the program was to evaluate the technical feasibility of utilizing advanced ceramics to increase peak engine operating temperature, and to evaluate the performance benefits of such an increase. Manufacturing cost estimates were also developed for various ceramic engine components and compared with conventional metallic engine component costs.

  19. Dental ceramics coated with bioactive glass: Surface changes after exposure in a simulated body fluid under static and dynamic conditions

    NASA Astrophysics Data System (ADS)

    Papadopoulou, L.; Kontonasaki, E.; Zorba, T.; Chatzistavrou, X.; Pavlidou, E.; Paraskevopoulos, K.; Sklavounos, S.; Koidis, P.

    2003-07-01

    Bioactive materials develop a strong bond with living tissues through a carbonate-containing hydroxyapatite layer, similar to that of bone. The fabrication of a thin bioactive glass coating on dental ceramics used in metal-ceramic restorations, could provide a bioactive surface, which in combination with a tissue regenerative technique could lead to periodontal tissues attachment. The aim of this study was the in vitro investigation of the surface structure changes of dental ceramics used in metal-ceramic restorations, coated with a bioactive glass heat-treated at 950 °C, after exposure in a simulated body fluid (SBF) under two different soaking conditions. Coating of dental ceramics with a bioactive glass resulted in the formation of a stable and well bonded with the ceramic substrate thin layer. The growth of a well-attached carbonate apatite layer on their surface after immersion in a simulated body fluid is well evidenced under both experimental conditions, although in static environment the rate of apatite growth is constant and the grown layers seem to be more dense and compact compared with the respective layers observed on specimens under dynamic conditions.

  20. Hydroxyapatite Growth Inhibition Effect of Pellicle Statherin Peptides.

    PubMed

    Xiao, Y; Karttunen, M; Jalkanen, J; Mussi, M C M; Liao, Y; Grohe, B; Lagugné-Labarthet, F; Siqueira, W L

    2015-08-01

    In our recent studies, we have shown that in vivo-acquired enamel pellicle is a sophisticated biological structure containing a significant portion of naturally occurring salivary peptides. From a functional aspect, the identification of peptides in the acquired enamel pellicle is of interest because many salivary proteins exhibit functional domains that maintain the activities of the native protein. Among the in vivo-acquired enamel pellicle peptides that have been newly identified, 5 peptides are derived from statherin. Here, we assessed the ability of these statherin pellicle peptides to inhibit hydroxyapatite crystal growth. In addition, atomistic molecular dynamics (MD) simulations were performed to better understand the underlying physical mechanisms of hydroxyapatite growth inhibition. A microplate colorimetric assay was used to quantify hydroxyapatite growth. Statherin protein, 5 statherin-derived peptides, and a peptide lacking phosphate at residues 2 and 3 were analyzed. Statherin peptide phosphorylated on residues 2 and 3 indicated a significant inhibitory effect when compared with the 5 other peptides (P < 0.05). MD simulations showed a strong affinity and fast adsorption to hydroxyapatite for phosphopeptides, whereas unphosphorylated peptides interacted weakly with the hydroxyapatite. Our data suggest that the presence of a covalently linked phosphate group (at residues 2 and 3) in statherin peptides modulates the effect of hydroxyapatite growth inhibition. This study provides a mechanism to account for the composition and function of acquired enamel pellicle statherin peptides that will contribute as a base for the development of biologically stable and functional synthetic peptides for therapeutic use against dental caries and/or periodontal disease. PMID:26116492

  1. Ceramic tamper-revealing seals

    DOEpatents

    Kupperman, D.S.; Raptis, A.C.; Sheen, S.H.

    1992-12-08

    A flexible metal or ceramic cable is described with composite ceramic ends, or a U-shaped ceramic connecting element attached to a binding element plate or block cast from alumina or zirconium, and connected to the connecting element by shrink fitting. 7 figs.

  2. Assessment of ceramic membrane filters

    SciTech Connect

    Ahluwalia, R.K.; Geyer, H.K.; Im, K.H.

    1995-08-01

    The objectives of this project include the development of analytical models for evaluating the fluid mechanics of membrane coated, dead-end ceramic filters, and to determine the effects of thermal and thermo-chemical aging on the material properties of emerging ceramic hot gas filters. A honeycomb cordierite monolith with a thin ceramic coating and a rigid candle filter were evaluated.

  3. Ceramic coatings on smooth surfaces

    NASA Technical Reports Server (NTRS)

    Miller, R. A. (Inventor); Brindley, W. J. (Inventor); Rouge, C. J. (Inventor)

    1991-01-01

    A metallic coating is plasma sprayed onto a smooth surface of a metal alloy substitute or on a bond coating. An initial thin ceramic layer is low pressure sprayed onto the smooth surface of the substrate or bond coating. Another ceramic layer is atmospheric plasma sprayed onto the initial ceramic layer.

  4. Ceramic regenerator program

    NASA Technical Reports Server (NTRS)

    Franklin, Jerrold E.

    1991-01-01

    The feasibility of fabricating an Air Turbo Ramjet (ATR) regenerator containing intricate hydraulic passages from a ceramic material in order to allow operation with high temperature combustion gas and to reduce weight as compared with metallic materials was demonstrated. Platelet technology, ceramic tape casting, and multilayer ceramic packaging techniques were used in this fabrication of subscale silicon nitride components. Proof-of-concept demonstrations were performed to simulate a methane cooled regenerator for an ATR engine. The regenerator vane was designed to operate at realistic service conditions, i.e., 600 psi in a 3500 R (3040 F), 500 fps combustion gas environment. A total of six regenerators were fabricated and tested. The regenerators were shown to be able to withstand internal pressurization to 1575 psi. They were subjected to testing in 500 fps, 3560 R (3100 F) air/propane combustion products and were operated satisfactorily for an excess of 100 hr and 40 thermal cycles which exceeded 2460 R (2000 F).

  5. Whisker reinforced glass ceramic

    SciTech Connect

    Hirschfeld, D.A.; Brown, J.J. Jr.

    1996-06-03

    The process for making an in-situ whisker reinforced glass-ceramic that is up to 1.5 times as strong as conventional glass-ceramics was developed at Virginia Tech and patented in 1993. This technology has been identified as having commercial potential for use in high temperature heat exchanger applications for the electric power generation field by the National Center for Appropriate Technology (NCAT). This technology was licensed by MATVA, Inc., a small Virginia business, for further development. In particular, the goal of this project was to develop a property database and conduct initial testing of heat exchanger prototypes to demonstrate its potential application. This final report describes how the glass precursor was formed, physical properties of the glass-ceramic, techniques for making heat exchanger prototypes.

  6. Erosion of composite ceramics

    SciTech Connect

    Routbort, J.L.

    1992-08-01

    The theoretical basis to describe solid-particle erosion of monolithic ceramics is well developed. In many cases, the models can account for the impact velocity, impact angle and erodent-size dependencies of the steady-state erosion rate. In addition, the models account for effects of materials parameters such as fracture toughness and hardness. Steady-state erosion measurements on a wide variety of composite ceramics, including SiC whisker-reinforced Al{sub 2}O{sub 3}, Si{sub 3}N{sub 4} containing Si{sub 3}N{sub 4} or SiC whiskers, Y{sub 2}O{sub 3}-stabilized ZrO{sub 2} reinforced with SiC whiskers, and duplex-microstructure Si{sub 3}N{sub 4} have been reported. The theories developed for monolithic ceramics are, however, less successful in describing the results for composites.

  7. Erosion of composite ceramics

    SciTech Connect

    Routbort, J.L.

    1992-08-01

    The theoretical basis to describe solid-particle erosion of monolithic ceramics is well developed. In many cases, the models can account for the impact velocity, impact angle and erodent-size dependencies of the steady-state erosion rate. In addition, the models account for effects of materials parameters such as fracture toughness and hardness. Steady-state erosion measurements on a wide variety of composite ceramics, including SiC whisker-reinforced Al[sub 2]O[sub 3], Si[sub 3]N[sub 4] containing Si[sub 3]N[sub 4] or SiC whiskers, Y[sub 2]O[sub 3]-stabilized ZrO[sub 2] reinforced with SiC whiskers, and duplex-microstructure Si[sub 3]N[sub 4] have been reported. The theories developed for monolithic ceramics are, however, less successful in describing the results for composites.

  8. Ceramic vane drive joint

    DOEpatents

    Smale, Charles H.

    1981-01-01

    A variable geometry gas turbine has an array of ceramic composition vanes positioned by an actuating ring coupled through a plurality of circumferentially spaced turbine vane levers to the outer end of a metallic vane drive shaft at each of the ceramic vanes. Each of the ceramic vanes has an end slot of bow tie configuration including flared end segments and a center slot therebetween. Each of the vane drive shafts has a cross head with ends thereof spaced with respect to the sides of the end slot to define clearance for free expansion of the cross head with respect to the vane and the cross head being configured to uniformly distribute drive loads across bearing surfaces of the vane slot.

  9. Enhanced osteoblast and osteoclast responses to a thin film sputtered hydroxyapatite coating.

    PubMed

    Hao, J; Kuroda, S; Ohya, K; Bartakova, S; Aoki, H; Kasugai, S

    2011-06-01

    A sputtering technique followed by a low temperature hydrothermal treatment has been demonstrated to produce a dense-and-bioactive hydroxyapatite thin film coating. The purpose of the present study was to investigate osteoblast and osteoclast responses to the hydroxyapatite coated plates and titanium plates with similar roughness. Rat bone marrow stromal cells were cultured on these plates to induce osteoblasts. The cells showed a significantly enhanced proliferation on the hydroxyapatite surface, accompanied by increase of osteoblastic phenotypes. The co-cultured osteoclasts exhibited the significantly different cell number and morphology between the hydroxyapatite and the titanium surfaces. A series of osteoclast marker genes were more stimulated on the hydroxyapatite and thirty two percent of the hydroxyapatite surface area could be resorbed by osteoclasts. The thin film sputtered hydroxyapatite could provide a favorable surface for both osteoblast and osteoclast formation and their function, indicating its good osteoconductivity and biodegradability. PMID:21567286

  10. Aminosilane as an effective binder for hydroxyapatite-gelatin nanocomposites.

    PubMed

    Luo, Tzy-Jiun M; Ko, Ching-Chang; Chiu, Chi-Kai; Llyod, Jacob; Huh, Uk

    2010-02-01

    Aminosilane has been explored as an alternative chemical linker to facilitate the binding and solidification of hydroxyapatite-gelatin nanocomposite at room temperature, which was synthesized using co-precipitation method in the presence of gelatin. This aminosilane treatment was found effective at low concentration (~25 μL/mL) and the solidification and dehydration of hydroxyapatite-gelatin slurry completes within hours depending on the amount of aminosilane. The resulting sample exhibits compressive strength of 133 MPa, about 40% higher than glutaraldehyde treated samples, and shows good biocompatibility based on cell adhesion, proliferation, alkaline phosphate synthesis, and mineralization studies. PMID:23833395

  11. Aminosilane as an effective binder for hydroxyapatite-gelatin nanocomposites

    PubMed Central

    Luo, Tzy-Jiun M.; Ko, Ching-Chang; Chiu, Chi-Kai; Llyod, Jacob; Huh, Uk

    2013-01-01

    Aminosilane has been explored as an alternative chemical linker to facilitate the binding and solidification of hydroxyapatite-gelatin nanocomposite at room temperature, which was synthesized using co-precipitation method in the presence of gelatin. This aminosilane treatment was found effective at low concentration (~25 μL/mL) and the solidification and dehydration of hydroxyapatite-gelatin slurry completes within hours depending on the amount of aminosilane. The resulting sample exhibits compressive strength of 133 MPa, about 40% higher than glutaraldehyde treated samples, and shows good biocompatibility based on cell adhesion, proliferation, alkaline phosphate synthesis, and mineralization studies. PMID:23833395

  12. In vivo study on hydroxyapatite scaffolds with trabecular architecture for bone repair.

    PubMed

    Appleford, Mark R; Oh, Sunho; Oh, Namsik; Ong, Joo L

    2009-06-15

    The objective of this research was to investigate the bone formation and angio-conductive potential of hydroxyapatite (HA) scaffolds closely matched to trabecular bone in a canine segmental defect after 3 and 12 weeks post implantation. Histomorphometric comparisons were made between naturally forming trabecular bone (control) and defects implanted with scaffolds fabricated with micro-size (M-HA) and nano-size HA (N-HA) ceramic surfaces. Scaffold architecture was similar to trabecular bone formed in control defects at 3 weeks. No significant differences were identified between the two HA scaffolds; however, significant bone in-growth was observed by 12 weeks with 43.9 +/- 4.1% and 50.4 +/- 8.8% of the cross-sectional area filled with mineralized bone in M-HA and N-HA scaffolds, respectively. Partially organized, lamellar collagen fibrils were identified by birefringence under cross-polarized light at both 3 and 12 weeks post implantation. Substantial blood vessel infiltration was identified in the scaffolds and compared with the distribution and diameter of vessels in the surrounding cortical bone. Vessels were less numerous but significantly larger than native cortical Haversian and Volkmann canals reflecting the scaffold architecture where open spaces allowed interconnected channels of bone to form. This study demonstrated the potential of trabecular bone modeled, highly porous and interconnected, HA scaffolds for regenerative orthopedics. PMID:18478555

  13. Structural and mechanical study of the sintering effect in hydroxyapatite doped with iron oxide

    NASA Astrophysics Data System (ADS)

    Filho, F. P.; Nogueira, R. E. F. Q.; Graça, M. P. F.; Valente, M. A.; Sombra, A. S. B.; Silva, C. C.

    2008-10-01

    Calcium phosphates are very important for applications in medicine due to their properties such as biocompatibility and bioactivity. In order to improve their properties, substitution of calcium with other ions has been proposed. Partial substitution of calcium by different ions has been made as a way to improve the properties of the calcium phosphates and also to allow new applications of apatites in medicine. In this work, hydroxyapatite [Ca 10(PO 4) 6(OH) 2-HAP], prepared by high-energy dry milling (20 h), was mixed with different amounts of iron oxide (0.5, 1, 2.5 and 5 wt%). The mixtures were calcinated at 900 °C for 5 h with a heating rate of 3 °C/min in an attempt to introduce the iron oxide in the HAP structure. Small discs (12.5 mm ∅) were uniaxially pressed under a load of 2 t for 2 min. The pellets were sintered at 1000, 1200 and 1300 °C for 5 h in air. The main purpose of this work is to study why the iron oxide concentration and the heat treatment of the samples change the microhardness of the obtained ceramics. The sintered samples were characterized by X-ray diffraction (XRD), Vickers Microhardness and scanning electron microscopy (SEM).

  14. The RIVET: a novel technique involving absorbable fixation for hydroxyapatite osteosynthesis.

    PubMed

    Shido, Hirokazu; Sakamoto, Yoshiaki; Miwa, Tomoru; Ohira, Takayuki; Yoshida, Kazunari; Kishi, Kazuo

    2013-05-01

    Cranioplasty using custom-made hydroxyapatite (HAP) ceramic implants is a common procedure for the repair of skull defects. The advantages of using HAP are that it is nonmetallic, unlike titanium; biocompatible; and osteoconductive. Furthermore, it can be molded to any complex shape that may be needed. A disadvantage is that titanium screws and plates are in development for its fixation. We developed a technique for implant fixation using bioabsorbable screws and plates, and named this technique RIVET: resorbable immobilization for vacuolar en bloc technique.Before each operation, the implant was customized for the patient in question on the basis of models prepared using computed tomography data. The bioabsorbable plates were attached to the implant by drilling, tapping, and screwing, as shown in the video (http://links.lww.com/SCS/A43). The interior portion of the screw was then melted to flatten it against the internal surface of the implant, forming a rivet to join the plate and HAP implant.We used this technique for cranial reconstruction in 2 patients, with satisfying and functional results. We did not encounter any complications.In conclusion, the technique described here allows surgeons to fix implants and plates together more rigidly, giving a better result than possible with previous methods. PMID:23714917

  15. Effect of the deposition temperature on corrosion resistance and biocompatibility of the hydroxyapatite coatings

    NASA Astrophysics Data System (ADS)

    Vladescu, A.; Braic, M.; Azem, F. Ak; Titorencu, I.; Braic, V.; Pruna, V.; Kiss, A.; Parau, A. C.; Birlik, I.

    2015-11-01

    Hydroxyapatite (HAP) ceramics belong to a class of calcium phosphate-based materials, which have been widely used as coatings on titanium medical implants in order to improve bone fixation and thus to increase the lifetime of the implant. In this study, HAP coatings were deposited from pure HAP targets on Ti6Al4V substrates using the radio-frequency magnetron sputtering technique at substrate temperatures ranging from 400 to 800 °C. The surface morphology and the crystallographic structure of the films were investigated by atomic force microscopy (AFM), scanning electron microscopy (SEM) and X-ray diffraction (XRD). The corrosion resistance of the coatings in saliva solution at 37 °C was evaluated by potentiodynamic polarization. Additionally, the human osteosarcoma cell line (MG-63) was used to test the biocompatibility of the coatings. The results showed that all of the coatings grown uniformly and that the increasing substrate temperature induced an increase in their crystallinity. Corrosion performance of the coatings was improved with the increase of the substrate temperature from 400 °C to 800 °C. Furthermore, all the coatings support the attachment and growth of the osteosarcoma cells with regard to the in vitro test findings.

  16. A novel squid pen chitosan/hydroxyapatite/β-tricalcium phosphate composite for bone tissue engineering.

    PubMed

    Shavandi, Amin; Bekhit, Alaa El-Din A; Sun, Zhifa; Ali, Azam; Gould, Maree

    2015-10-01

    Squid pen chitosan was used in the fabrication of biocomposite scaffolds for bone tissue engineering. Hydroxyapatite (HA) and beta-tricalcium phosphate (β-TCP) obtained from waste mussel shells were used as the calcium phosphate source. The composite was prepared using 2.5% tripolyphosphate (TPP) and 1% glycerol as a cross-linker and plasticizer, respectively. The weight percent (wt.%) ratios of the ceramic components in the composite were 20/10/70, 30/20/50 and 40/30/30 (HA/β-TCP/Chi). The biodegradation rate and structural properties of the scaffolds were investigated. Scanning electron microscopy (SEM) and microCT(μCT) results indicated that the composites have a well defined lamellar structure with an average pore size of 200 μm. The porosity of the composites decreased from 88 to 56% by increasing the ratio of HA/β-TCP from 30 to 70%. After 28 days of incubation in a physiological solution, the scaffolds were degraded by approximately 30%. In vitro investigations showed that the composites were cytocompatible and supported the growth of L929 and Saos-2 cells. The obtained data suggests that the squid pen chitosan composites are potential candidates for bone regeneration. PMID:26117768

  17. Lamellar Spacing in Cuboid Hydroxyapatite Scaffolds Regulates Bone Formation by Human Bone Marrow Stromal Cells

    PubMed Central

    Afghani, Shahrzad; Franco, Jaime; Launey, Max; Marshall, Sally; Marshall, Grayson W.; Nissenson, Robert; Lee, Janice; Tomsia, Antoni P.; Saiz, Eduardo

    2011-01-01

    Background A major goal in bone engineering is the creation of large volume constructs (scaffolds and stem cells) that bear load. The scaffolds must satisfy two competing requirements—they need be sufficiently porous to allow nutrient flow to maintain cell viability, yet sufficiently dense to bear load. We studied the effect of scaffold macroporosity on bone formation and scaffold strength, for bone formed by human bone marrow stromal cells. Methods Rigid cubical hydroxyapatite/tricalcium phosphate scaffolds were produced by robo-casting. The ceramic line thickness was held constant, but the distance between adjacent lines was either 50, 100, 200, 500, or 1000 μm. Cultured human bone marrow stromal cells were combined with the scaffolds in vitro; transplants were placed into the subcutis of immunodeficient mice. Transplants were harvested 9, 18, 23, 38, or 50 weeks later. Bone formation and scaffold strength were analyzed using histology and compression testing. Results Sixty transplants were evaluated. Cortical bone increased with transplant age, and was greatest among 500 μm transplants. In contrast, maximum transplant strength was greatest among 200 μm transplants. Conclusions Lamellar spacing within scaffolds regulates the extent of bone formation; 500 μm yields the most new bone, whereas 200 μm yields the strongest transplants. PMID:21294634

  18. Engineering nanocages with polyglutamate domains for coupling to hydroxyapatite biomaterials and allograft bone.

    PubMed

    Culpepper, Bonnie K; Morris, David S; Prevelige, Peter E; Bellis, Susan L

    2013-03-01

    Hydroxyapatite (HA) is the principal constituent of bone mineral, and synthetic HA is widely used as a biomaterial for bone repair. Previous work has shown that polyglutamate domains bind selectively to HA and that these domains can be utilized to couple bioactive peptides onto many different HA-containing materials. In the current study we have adapted this technology to engineer polyglutamate domains into cargo-loaded nanocage structures derived from the P22 bacteriophage. P22 nanocages have demonstrated significant potential as a drug delivery system due to their stability, large capacity for loading with a diversity of proteins and other types of cargo, and ability to resist degradation by proteases. Site-directed mutagenesis was used to modify the primary coding sequence of the P22 coat protein to incorporate glutamate-rich regions. Relative to wild-type P22, the polyglutamate-modified nanocages (E2-P22) exhibited increased binding to ceramic HA disks, particulate HA and allograft bone. Furthermore, E2-P22 binding was HA selective, as evidenced by negligible binding of the nanocages to non-HA materials including polystyrene, agarose, and polycaprolactone (PCL). Taken together these results establish a new mechanism for the directed coupling of nanocage drug delivery systems to a variety of HA-containing materials commonly used in diverse bone therapies. PMID:23312905

  19. Characterization of gas tunnel type plasma sprayed hydroxyapatite-nanostructure titania composite coatings

    NASA Astrophysics Data System (ADS)

    Yugeswaran, S.; Kobayashi, A.; Ucisik, A. Hikmet; Subramanian, B.

    2015-08-01

    Hydroxyapatite (HA) can be coated onto metal implants as a ceramic biocompatible coating to bridge the growth between implants and human tissue. Meanwhile many efforts have been made to improve the mechanical properties of the HA coatings without affecting its bioactivity. In the present study, nanostructure titania (TiO2) was mixed with HA powder and HA-nanostructure TiO2 composite coatings were produced by gas tunnel type plasma spraying torch under optimized spraying conditions. For this purpose, composition of 10 wt% TiO2 + 90 wt% HA, 20 wt% TiO2 + 80 wt% HA and 30 wt% TiO2 + 70 wt% HA were selected as the feedstock materials. The phase, microstructure and mechanical properties of the coatings were characterized. The obtained results validated that the increase in weight percentage of nanostructure TiO2 in HA coating significantly increased the microhardness, adhesive strength and wear resistance of the coatings. Analysis of the in vitro bioactivity and cytocompatibility of the coatings were done using conventional simulated body fluid (c-SBF) solution and cultured green fluorescent protein (GFP) labeled marrow stromal cells (MSCs) respectively. The bioactivity results revealed that the composite coating has bio-active surface with good cytocompatibility.

  20. X-ray diffraction characterization of crystallinity and phase composition in plasma-sprayed hydroxyapatite coatings

    NASA Astrophysics Data System (ADS)

    Prevéy, Paul S.

    2000-09-01

    Orthopedic and dental implants consisting of a metallic substrate plasma spray coated with hydroxyapatite (HA) are currently used in reconstructive surgery. The crystalline phases present in the calcium phosphate ceramic and the degree of crystallinity must be controlled for medical applications. X-ray diffraction (XRD) is routinely employed to characterize the phase composition and percent crystallinity in both biological and sintered HA. However, application of the same XRD methods to plasma-sprayed coatings is complicated by the potential presence of several crystalline contaminant phases and an amorphous component. To overcome the complexities of characterizing plasma-sprayed HA coatings, an external standard method of XRD quantitative analysis has been developed that can be applied nondestructively. Data collection and reduction strategies allowing separation of intensity diffracted from commonly occurring phases and the amorphous fraction are presented. The method is applied to coating samples, and detection limits and sources of error are discussed. Repeability and accuracy are demonstrated with powder mixtures of known composition.

  1. Low-Energy Plasma Spray (LEPS) Deposition of Hydroxyapatite/Poly-ɛ-Caprolactone Biocomposite Coatings

    NASA Astrophysics Data System (ADS)

    Garcia-Alonso, Diana; Parco, Maria; Stokes, Joseph; Looney, Lisa

    2012-01-01

    Thermal spraying is widely employed to deposit hydroxyapatite (HA) and HA-based biocomposites on hip and dental implants. For thick HA coatings (>150 μm), problems are generally associated with the build-up of residual stresses and lack of control of coating crystallinity. HA/polymer composite coatings are especially interesting to improve the pure HA coatings' mechanical properties. For instance, the polymer may help in releasing the residual stresses in the thick HA coatings. In addition, the selection of a bioresorbable polymer may enhance the coatings' biological behavior. However, there are major challenges associated with spraying ceramic and polymeric materials together because of their very different thermal properties. In this study, pure HA and HA/poly-ɛ-caprolactone (PCL) thick coatings were deposited without significant thermal degradation by low-energy plasma spraying (LEPS). PCL has never been processed by thermal spraying, and its processing is a major achievement of this study. The influence of selected process parameters on microstructure, composition, and mechanical properties of HA and HA/PCL coatings was studied using statistical design of experiments (DOE). The HA deposition rate was significantly increased by the addition of PCL. The average porosity of biocomposite coatings was slightly increased, while retaining or even improving in some cases their fracture toughness and microhardness. Surface roughness of biocomposites was enhanced compared with HA pure coatings. Cell culture experiments showed that murine osteoblast-like cells attach and proliferate well on HA/PCL biocomposite deposits.

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

    NASA Astrophysics Data System (ADS)

    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.

  3. Engineering nanocages with polyglutamate domains for coupling to hydroxyapatite biomaterials and allograft bone

    PubMed Central

    Culpepper, Bonnie K.; Morris, David S.; Prevelige, Peter E.; Bellis, Susan L.

    2013-01-01

    Hydroxyapatite (HA) is the principal constituent of bone mineral, and synthetic HA is widely used as a biomaterial for bone repair. Previous work has shown that polyglutamate domains bind selectively to HA and that these domains can be utilized to couple bioactive peptides onto many different HA-containing materials. In the current study we have adapted this technology to engineer polyglutamate domains into cargo-loaded nanocage structures derived from the P22 bacteriophage. P22 nanocages have demonstrated significant potential as a drug delivery system due to their stability, large capacity for loading with a diversity of proteins and other types of cargo, and ability to resist degradation by proteases. Site-directed mutagenesis was used to modify the primary coding sequence of the P22 coat protein to incorporate glutamate-rich regions. Relative to wild-type P22, the polyglutamate-modified nanocages (E2-P22) exhibited increased binding to ceramic HA disks, particulate HA and allograft bone. Furthermore, E2-P22 binding was HA selective, as evidenced by negligible binding of the nanocages to non-HA materials including polystyrene, agarose, and polycaprolactone (PCL). Taken together these results establish a new mechanism for the directed coupling of nanocage drug delivery systems to a variety of HA-containing materials commonly used in diverse bone therapies. PMID:23312905

  4. Suspension Rheology, Porosity and Mechanical Strength of Porous Hydroxyapatite Obtained by Gel-casting and Infiltration

    NASA Astrophysics Data System (ADS)

    González Ocampo, Jazmín; Escobar Jaramillo, Mateo; Escobar Sierra, Diana; Ossa Orozco, Claudia

    2016-02-01

    The gel-casting technique (GC) and infiltration of polymer foam combined with gel-casting (IG) were used to produce hydroxyapatite porous bodies. Due to the fact that the process begins with the preparation of the suspensions, it is necessary to know the rheological properties of the ceramic slurry. This is a critical factor needed to optimize the mechanical strength of the porous body obtained. Therefore, the rheological behavior of various HA slurries was assessed. 40 and 50% solids and three different monomers were evaluated. Subsequently, the compressive strength and porosity of the porous bodies obtained were evaluated. The results revealed that the chemical composition of each monomer can affect the dispersion and rheological properties of the suspension, which directly affects the mechanical properties of the porous bodies. The porous bodies obtained by the GC technique showed strengths higher than those obtained by IG compression. The control executed over the rheology of the suspension was more effective in bodies produced by GC, because IG pyrolysis of polyurethane foam also influenced the mechanical properties of the final product.

  5. Microwave processed nanocrystalline hydroxyapatite: Simultaneous enhancement of mechanical and biological properties

    PubMed Central

    Bose, Susmita; Dasgupta, Sudip; Tarafder, Solaiman; Bandyopadhyay, Amit

    2010-01-01

    Despite excellent bioactivity of hydroxyapatite (HA) ceramics, poor mechanical strength has limited its applications primarily to coatings and other non-load bearing areas as bone grafts. Using synthesized HA nanopowder, dense compacts with grain sizes in nanometers to micrometers were processed via microwave sintering between 1000 and 1150 °C for 20 minutes. Here we demonstrate that mechanical properties, such as compressive strength, hardness and indentation fracture toughness of HA compacts increased with a decrease in grain size. HA with 168± 86 nm grain size showed the highest compressive strength of 395±42 MPa, hardness of 8.4±0.4 GPa and indentation fracture toughness of 1.9 ±0.2 MPam1/2. To study the in vitro biological properties, HA compacts with grain size between 168 nm and 1.16 µm were assessed for in vitro bone cell-materials interactions with human osteoblast cell line. Vinculin protein expression for cell attachment and bone cell proliferation using MTT assay showed surfaces with finer grains provided better bone cell-materials interactions than coarse grained samples. Our results indicate simultaneous improvements in mechanical and biological properties in microwave sintered HA compacts with nanoscale grain size. PMID:20230922

  6. Development of metal/hydroxyapatite composite surface coatings. Ph.D. Thesis

    SciTech Connect

    Dasarathy, H.

    1992-01-01

    Metal/ceramic composites containing calcium phosphates have shown considerable success in enhancing bone growth into implants, thereby providing cementless fixation. Calcium phosphate occurs in various phases. The extent of compatibility of the composites to the hosts depend upon the phase of the calcium phosphate. A crystalline phase known as hydroxyapatite (HA) which naturally occurs in bones and teeth of animals has proved to enhance bone growth. This work involved development of a composite that will retain both the biological properties of HA and the mechanical properties of the metal. In this method, HA was codeposited electrolytically on a metal substrate in a metal matrix to provide adequate adhesion to the substrate. Codeposited HA on the surface was characterized using FTIR and Raman spectroscopy to ensure that HA structure remained unaltered throughout the conditions employed during the process. The development of the composite was carried out in two phases. Phase 1 consisted of codeposition of HA in a single metal matrix, characterization of HA and testing the viability of the process to all substrate geometry. In the second phase, a process was developed to electrolytically deposit cobalt, chromium, molybdenum alloy (vitallium) and then codeposit HA in that alloy matrix on substrates. The plated alloy was characterized by x-ray photoelectron spectroscopy, x-ray diffraction, energy dispersive spectroscopy and compared with similar analyses for cast vitallium alloy. The deposited alloy was also tested for corrosion and substrate adhesion.

  7. Poly (D,L-lactide)/nano-hydroxyapatite composite scaffolds for bone tissue engineering and biocompatibility evaluation.

    PubMed

    Ren, Jie; Zhao, Peng; Ren, Tianbin; Gu, Shuying; Pan, Kefeng

    2008-03-01

    Biodegradable polymer/bioceramic composite scaffolds can overcome the limitations of conventional ceramic bone substitutes such as brittleness and difficulty in shaping. However, conventional methods for fabricating polymer/bioceramic composite scaffolds often use organic solvents (e.g., the solvent casting and particulate leaching (SC/PL) method), which might be harmful to cells or tissues. In this study, Poly (D,L-lactide)/nano-hydroxyapatite (PDLLA/NHA) composites were prepared by in-situ polymerization, and highly porous scaffolds were fabricated using a novel method, supercritical CO2/salt-leaching method (SC CO2/SL). The materials and scaffolds were investigated by scanning electronic microscopy (SEM), transmission electronic microscopy (TEM) and gel permeation chromatography (GPC). GPC showed that the molecular weight of composites decreased with increase of NHA content. However, the water absorption and compressive strength increased dramatically. The SEM micrographs showed that the scaffolds with pore size about 250 microm were obtained by controlling parameters of SC CO2/SL. The biocompatibility of PDLLA/NHA porous scaffolds were evaluated in vitro and in vivo. The evaluation on the cytotoxicity were carried out by cell relative growth rate (RGR) method and cell direct contact method. The cytotoxicity of these scaffolds was in grade I according to ISO 10993-1. There was no toxicosis and death cases observed in acute systemic toxicity test. And histological observation of the tissue response (1 and 9 weeks after the implantation) showed that there are still some slight inflammation responses. PMID:17701303

  8. Characterization of Multiwalled Carbon Nanotube-Reinforced Hydroxyapatite Composites Consolidated by Spark Plasma Sintering

    PubMed Central

    Kim, Duk-Yeon; Han, Young-Hwan; Lee, Jun Hee; Kang, Inn-Kyu; Jang, Byung-Koog; Kim, Sukyoung

    2014-01-01

    Pure HA and 1, 3, 5, and 10 vol% multiwalled carbon nanotube- (MWNT-) reinforced hydroxyapatite (HA) were consolidated using a spark plasma sintering (SPS) technique. The relative density of pure HA increased with increasing sintering temperature, but that of the MWNT/HA composite reached almost full density at 900°C, and then decreased with further increases in sintering temperature. The relative density of the MWNT/HA composites increased with increasing MWNT content due to the excellent thermal conductivity of MWNTs. The grain size of MWNT/HA composites decreased with increasing MWNT content and increased with increasing sintering temperature. Pull-out toughening of the MWNTs of the MWNT/HA composites was observed in the fractured surface, which can be used to predict the improvement of the mechanical properties. On the other hand, the existence of undispersed or agglomerate MWNTs in the MWNT/HA composites accompanied large pores. The formation of large pores increased with increasing sintering temperature and MWNT content. The addition of MWNT in HA increased the hardness and fracture toughness by approximately 3~4 times, despite the presence of large pores produced by un-dispersed MWNTs. This provides strong evidence as to why the MWNTs are good candidates as reinforcements for strengthening the ceramic matrix. The MWNT/HA composites did not decompose during SPS sintering. The MWNT-reinforced HA composites were non-toxic and showed a good cell affinity and morphology in vitro for 1 day. PMID:24724100

  9. Biologic Response to Carbonated Hydroxyapatite Associated with Orthopedic Device: Experimental Study in a Rabbit Model

    PubMed Central

    Saoudi, Mongi; Badraoui, Riadh; Rebai, Tarek; Oudadesse, Hassane; Ellouz, Zoubaier; Keskese, Hassib; El Feki, Abdelfattah; El Feki, Hafed

    2012-01-01

    Background Carbonated hydroxyapatite (CHA) and related calcium phosphates have been studied for many years as implant materials due to their similarity with the mineral phase of bone. The main limitation of CHA ceramics as well as other bioactive materials is that they have poor mechanical proprieties. It is thought that the mechanical device can cause an increase in metabolic activity and bone healing. In this study we investigated the reactivity and tissue behaviour of implanted CHA biomaterial reinforced by mini external fixator. Methods The evaluation of biomaterial biocompatibility and osteogenesis was performed on a rabbit model over a period of 6 weeks by radiological, histological and scanning electron microscopy (SEM) coupled with energy dispersive X-ray SEM-energy-dispersive X-ray (EDX) analysis. Results While rabbits treated with CHA exhibited more bone formation, and fibrous tissue was observed when empty bone defects were observed. EDX analysis detected little calcium and phosphorus on the surface of the bone that was not implanted, while high content of calcium (62.7%) and phosphorus (38%) was found on the interface bone cement. Conclusions Bone repairing showed that the mini external fixator stimulated the ossification which was pushed when grafted by CHA. This effect may play an important role in the prevention of implant loosening. PMID:23109978

  10. Supported microporous ceramic membranes

    DOEpatents

    Webster, E.; Anderson, M.

    1993-12-14

    A method for the formation of microporous ceramic membranes onto a porous support includes placing a colloidal suspension of metal or metal oxide particles on one side of the porous support and exposing the other side of the porous support to a drying stream of gas or a reactive gas stream so that the particles are deposited on the drying side of the support as a gel. The gel so deposited can be sintered to form a supported ceramic membrane useful for ultrafiltration, reverse osmosis, or molecular sieving having mean pore sizes less than 100 Angstroms. 4 figures.

  11. Supported microporous ceramic membranes

    DOEpatents

    Webster, Elizabeth; Anderson, Marc

    1993-01-01

    A method for permformation of microporous ceramic membranes onto a porous support includes placing a colloidal suspension of metal or metal oxide particles on one side of the porous support and exposing the other side of the porous support to a drying stream of gas or a reactive gas stream so that the particles are deposited on the drying side of the support as a gel. The gel so deposited can be sintered to form a supported ceramic membrane useful for ultrafiltration, reverse osmosis, or molecular sieving having mean pore sizes less than 100 Angstroms.

  12. Performance of Dental Ceramics

    PubMed Central

    Rekow, E.D.; Silva, N.R.F.A.; Coelho, P.G.; Zhang, Y.; Guess, P.; Thompson, V.P.

    2011-01-01

    The clinical success of modern dental ceramics depends on an array of factors, ranging from initial physical properties of the material itself, to the fabrication and clinical procedures that inevitably damage these brittle materials, and the oral environment. Understanding the influence of these factors on clinical performance has engaged the dental, ceramics, and engineering communities alike. The objective of this review is to first summarize clinical, experimental, and analytic results reported in the recent literature. Additionally, it seeks to address how this new information adds insight into predictive test procedures and reveals challenges for future improvements. PMID:21224408

  13. Environment Conscious Ceramics (Ecoceramics)

    NASA Technical Reports Server (NTRS)

    Singh, Mrityunjay; Levine, Stanley R. (Technical Monitor)

    2000-01-01

    Environment conscious ceramics (Ecoceramics) are a new class of materials, which can be produced with renewable natural resources (wood) or wood wastes (wood sawdust). Silicon carbide-based ecoceramics have been fabricated by reactive infiltration of carbonaceous preforms by molten silicon or silicon-refractory metal alloys. These carbonaceous preforms have been fabricated by pyrolysis of solid wood bodies at 1000 C. The fabrication approach, microstructure, and mechanical properties of SiC-based ecoceramics are presented. Ecoceramics have tailorable properties and behave like ceramic materials manufactured by conventional approaches.

  14. Ceramic component for electrodes

    DOEpatents

    Marchant, David D.

    1979-01-01

    A ceramic component suitable for preparing MHD generator electrodes consists of HfO.sub.2 and sufficient Tb.sub.4 O.sub.7 to stabilize at least 60 volume percent of the HfO.sub.2 into the cubic structure. The ceramic component may also contain a small amount of PrO.sub.2, Yb.sub.2 O.sub.3 or a mixture of both to improve stability and electronic conductivity of the electrode. The component is highly resistant to corrosion by molten potassium seed and molten coal slag in the MHD fluid and exhibits both ionic and electronic conductivity.

  15. Ceramic powder compaction

    SciTech Connect

    Glass, S.J.; Ewsuk, K.G.; Mahoney, F.M.

    1995-12-31

    With the objective of developing a predictive model for ceramic powder compaction we have investigated methods for characterizing density gradients in ceramic powder compacts, reviewed and compared existing compaction models, conducted compaction experiments on a spray dried alumina powder, and conducted mechanical tests and compaction experiments on model granular materials. Die filling and particle packing, and the behavior of individual granules play an important role in determining compaction behavior and should be incorporated into realistic compaction models. These results support the use of discrete element modeling techniques and statistical mechanics principals to develop a comprehensive model for compaction, something that should be achievable with computers with parallel processing capabilities.

  16. Ceramic breeder materials

    SciTech Connect

    Johnson, C.E.; Kummerer, K.R.; Roth, E.

    1987-01-01

    Ceramic materials are under investigation as potential breeder material in fusion reactors. This paper will review candidate materials with respect to fabrication routes and characterization, properties in as-fabricated and irradiated condition, and experimental results from laboratory and inpile investigations on tritium transport and release. Also discussed are the resources of beryllium, which is being considered as a neutron multiplier. The comparison of ceramic properties that is attempted here aims at the identification of the most-promising material for use in a tritium breeding blanket. 82 refs., 12 figs., 5 tabs.

  17. Battery utilizing ceramic membranes

    DOEpatents

    Yahnke, M.S.; Shlomo, G.; Anderson, M.A.

    1994-08-30

    A thin film battery is disclosed based on the use of ceramic membrane technology. The battery includes a pair of conductive collectors on which the materials for the anode and the cathode may be spin coated. The separator is formed of a porous metal oxide ceramic membrane impregnated with electrolyte so that electrical separation is maintained while ion mobility is also maintained. The entire battery can be made less than 10 microns thick while generating a potential in the 1 volt range. 2 figs.

  18. Microwave sintering of ceramics

    SciTech Connect

    Snyder, W.B.

    1989-01-01

    Successful adaptation of microwave heating to the densification of ceramic materials require a marriage of microwave and materials technologies. Using an interdisciplinary team of microwave and materials engineers, we have successfully demonstrated the ability to density ceramic materials over a wide range of temperatures. Microstructural evolution during microwave sintering has been found to be significantly different from that observed in conventional sintering. Our results and those of others indicate that microwave sintering has the potential to fabricate components to near net shape with mechanical properties equivalent to hot pressed or hot isostatically pressed material. 6 refs., 11 figs.

  19. Femur bone repair in ovariectomized rats under the local action of alendronate, hydroxyapatite and the association of alendronate and hydroxyapatite

    PubMed Central

    Canettieri, Antonio Carlos Victor; Colombo, Carlos Eduardo Dias; Chin, Chung Man; Faig-Leite, Horácio

    2009-01-01

    An evaluation was made of the local action of alendronate sodium (A), hydroxyapatite (HA) and the association of both substances (A + HA), in different molar concentrations, on the femur bone repair of ovariectomized rats. Ninety-eight animals were divided into seven groups: control (C), starch (S), alendronate 1 mol (A1), alendronate 2 mols (A2), hydroxyapatite 1 mol (HA1), hydroxyapatite 2 mols (HA2) and the association of alendronate + hydroxyapatite (A + HA). Rats weighing about 250 g were ovariectomized and 2.5-mm diameter bone defects were made on the left femur 30 days later. Each experimental group had defects filled with appropriate material, except for group C (control). The animals were killed 7 and 21 days after surgery. Histological, histomorphometric and statistical analyses of bone neoformation in the bone defect site were performed. From the histological standpoint, the major differences occurred after 21 days. All specimens in groups C, S, HA1 and HA2 presented linear closure of the bone defect, and most animals in groups A1, A2 and A + HA showed no bone neoformation in the central area of the defect. No statistically significant difference was found among the experimental groups after 7 days; after 21 days, group HA2 presented the highest amount of neoformed bone. There was no significant difference among groups A1, A2 and A + HA in the two study periods. It was concluded that alendronate, either isolated or in association with hydroxyapatite, had an adverse effect on bone repair in this experimental model. Moreover, the hydroxyapatite used here proved to be biocompatible and osteoconductive, with group HA2 showing the best results. PMID:19765106

  20. Nanostructured glass–ceramic coatings for orthopaedic applications

    PubMed Central

    Wang, Guocheng; Lu, Zufu; Liu, Xuanyong; Zhou, Xiaming; Ding, Chuanxian; Zreiqat, Hala

    2011-01-01

    Glass–ceramics have attracted much attention in the biomedical field, as they provide great possibilities to manipulate their properties by post-treatments, including strength, degradation rate and coefficient of thermal expansion. In this work, hardystonite (HT; Ca2ZnSi2O7) and sphene (SP; CaTiSiO5) glass–ceramic coatings with nanostructures were prepared by a plasma spray technique using conventional powders. The bonding strength and Vickers hardness for HT and SP coatings are higher than the reported values for plasma-sprayed hydroxyapatite coatings. Both types of coatings release bioactive calcium (Ca) and silicon (Si) ions into the surrounding environment. Mineralization test in cell-free culture medium showed that many mushroom-like Ca and phosphorus compounds formed on the HT coatings after 5 h, suggesting its high acellular mineralization ability. Primary human osteoblasts attach, spread and proliferate well on both types of coatings. Higher proliferation rate was observed on the HT coatings compared with the SP coatings and uncoated Ti-6Al-4V alloy, probably due to the zinc ions released from the HT coatings. Higher expression levels of Runx2, osteopontin and type I collagen were observed on both types of coatings compared with Ti-6Al-4V alloy, possibly due to the Ca and Si released from the coatings. Results of this study point to the potential use of HT and SP coatings for orthopaedic applications. PMID:21292725

  1. Short-term studies using ceramic scaffolds in lapine model for osteochondral defect amelioration.

    PubMed

    Fernandez, F B; Shenoy, Sachin; Suresh Babu, S; Varma, H K; John, Annie

    2012-06-01

    This study was undertaken to glean preliminary information on the role of triphasic ceramic coated hydroxyapatite (HASi) and biphasic (alpha-tricalcium phosphate and hydroxyapatite based) calcium phosphate (BCP) for the development of osteochondral constructs. The proposed constructs were tested for performance in vitro with rabbit adipose-derived mesenchymal stem cells (RADMSCs) and further analysed in vivo in a lapine model for osteochondral defect amelioration. Desirable scaffolding architecture ensuring favourable conditions for cell attachment, nutrient exchange and neo-tissue organization was achieved by the synthesis of porous ceramic blocks and characterizations were carried out using x-ray diffraction and Fourier transform infrared spectroscopy. The cytocompatibility of the scaffold-cell combination product was evaluated using microscopy techniques that proved the scaffold to be non-cytotoxic and favourable for cell growth and proliferation. Short-term implantation studies were conducted with bare cylindrical HASi and BCP scaffolds, press fit deep into the bony bed of the median femoral condyles of the rabbit, which resulted in favourable specific in vivo response of de novo cartilage-like cells on the surface and sub-surface bony trabeculae. The generated pilot data will help to assess the severity of proposed procedures before embarking on scaled-up efforts. PMID:22406527

  2. Inhibition of hydroxyapatite formation by osteopontin phosphopeptides.

    PubMed Central

    Pampena, David A; Robertson, Karen A; Litvinova, Olga; Lajoie, Gilles; Goldberg, Harvey A; Hunter, Graeme K

    2004-01-01

    Osteopontin (OPN) is an acidic phosphoglycoprotein that is believed to function in the prevention of soft tissue calcification. In vitro studies have shown that OPN can inhibit the formation of hydroxyapatite (HA) and other biologically relevant crystal phases, and that this inhibitory activity requires phosphorylation of the protein; however, it is not known which phosphorylated residues are involved. We have synthesized peptides corresponding to four phosphoserine-containing sequences in rat OPN: OPN7-17, containing phosphoserines 10 and 11; OPN41-52, containing phosphoserines 46 and 47; OPN248-264, containing phosphoserines 250, 257 and 262; and OPN290-301, containing phosphoserines 295-297. The abilities of these peptides to inhibit de novo HA formation were determined using a constant-composition autotitration assay. All four OPN phosphopeptides caused a dose-dependent increase in nucleation lag time, but did not significantly affect subsequent formation of the crystals. However, OPN41-52 (inhibitory constant 73.5 min/microM) and OPN290-301 (72.2 min/microM) were approx. 4 times more potent inhibitors than OPN7-17 (19.7 min/microM) and OPN247-264 (16.3 min/microM). 'Scrambling' the amino acid sequence of OPN290-301 resulted in decreased potency (45.6 min/microM), whereas omission of the phosphate groups from this peptide caused a greater decrease (5.20 min/microM). These findings have identified phosphorylated sequences that are important for the ability of rat bone OPN to inhibit HA crystal formation, and suggest that negative-charge density is an important factor in this activity. PMID:14678013

  3. Biomechanical analysis of hydroxyapatite cement cranioplasty.

    PubMed

    Matic, Damir B; Manson, Paul N

    2004-05-01

    A recent review of the authors' experience with hydroxyapatite (HA) cement cranioplasties revealed a high infection rate. During removal of these implants, all were loose and fractured. Forty percent of these patients had a history of minor trauma at the site of cranioplasty before experiencing infection. Minor trauma may fracture HA cranioplasties and result in infection. The purpose of this study is to determine the force to fracture full- and partial-thickness cranial defects reconstructed with HA cement and to compare peak loads of differing HA cement cranioplasty techniques. Standardized craniotomy defects were created in five fresh cadaver heads. Full-thickness defects were reconstructed with either rigid or flexible titanium mesh and then covered with HA cement. Partial-thickness defects were reconstructed with HA alone. After setting, a uniaxial impact was delivered to each of the defects. Peak loads were recorded, and defects were examined for evidence of fracture.Predictable fractures of the HA cranioplasties occurred at 1200 N in all full-thickness defects reconstructed with mesh and a thin layer of HA. Implant loosening and chipping was similar to what was seen clinically in the authors' patients with infections. Full-thickness defects in which titanium mesh was shaped like a cup and filled with a thick layer of HA resist fracture at 1200 N. Partial-thickness defects reconstructed with HA alone also do not fracture at this peak load. Patient selection, defect characteristics, and reconstructive techniques are factors that need to be considered before using HA cement for cranioplasty purposes. PMID:15111799

  4. Osteoconductivity and osteoinductivity of porous hydroxyapatite coatings deposited by liquid precursor plasma spraying: in vivo biological response study.

    PubMed

    Huang, Yi; He, Jing; Gan, Lu; Liu, Xiaoguang; Wu, Yao; Wu, Fang; Gu, Zhong-wei

    2014-12-01

    The beneficial effect of a porous structure on the biological functions of calcium phosphate bulk ceramic or scaffold has been well documented. Nevertheless, the effect of a porous structure on the in vivo performance of hydroxyapatite (HA) coatings has been rarely reported, partly due to the difficulty in synthesizing porous HA coatings suitable for commercial applications. In this study, we have carried out a systematic in vivo study of porous HA-coated Ti implants (with and without surface modification) prepared by the liquid precursor plasma spraying process, in terms of its osteoconductivity and osteoinductivity. The results suggest the clear advantage of the porous structure over the dense structure, despite the pore structure (about 48% porosity and less than 100 μm average pore size) being far from the ideal pore structure reported for bulk ceramic. The porous HA-coated implant significantly promotes early bone ingrowth at the pre-generated defective region, and early fixation at the bone-implant interface, especially at early implantation time (one month), showing about 120% and 40% increases respectively over those of the dense HA-coated implants prepared by the conventional atmospheric plasma spraying process. Moreover, the porous structure can be readily used to incorporate collagen/rh-BMP2, which demonstrates clear ectopic bone formation. Overall, the results suggest the augmentation of bone ingrowth is significant for HA coatings with a porous structure, which is critical for the early fixation and long-term stability of medical implants. PMID:25384201

  5. Hydroxyapatite and tricalcium phosphate-coated cups with and without screw fixation: a randomized study of 64 hips.

    PubMed

    Thanner, J; Kärrholm, J; Herberts, P; Malchau, H

    2000-06-01

    Sixty-two patients (64 hips) were provided with porous press-fit cups (Trilogy), plasma-sprayed with a coating consisting of 70% hydroxyapatite and 30% tricalcium phosphate. The patients were randomized to a cup with cluster holes for adjunctive screw fixation (n = 30) or to a cup without holes (n = 34). Radiostereometry was used to study migration and wear. Up to 2 years median translations and rotations <0.2 mm and <0.2 degrees were recorded in the 2 groups, without any difference. The median annual proximal wear (0.11 and 0.12 mm) was within the expected range despite the use of a ceramic coating, and it did not differ between the 2 designs. Radiolucent lines were frequently seen postoperatively but diminished during the follow-up without any sign of migration into the gaps. At 2 years, the median Harris scores were 99 points (range, 51-100 points) in the group with and 98 points (range, 69-100 points) in the group without screws. The results indicate that early fixation can be achieved for ceramic-coated press-fit cups without using additional screw fixation. PMID:10884197

  6. Ceramic/ceramic total hip arthroplasty.

    PubMed

    Bizot, P; Nizard, R; Lerouge, S; Prudhommeaux, F; Sedel, L

    2000-01-01

    Alumina-on-alumina total hip arthroplasty has been used for 30 years, mainly in Europe. The theoretical advantages of this combination are represented by its remarkable sliding characteristics, its very low wear debris generation, and its sufficient fracture toughness. These advantages are achieved if the material is properly controlled with high density, high purity, and small grains. The authors summarize the results obtained with ceramic/ceramic total hip arthroplasty. Information is provided about in vivo behavior regarding wear debris characterization and quantification, and histological tissue examinations for inflammatory reactions, which were not encountered except when alumina debris was mixed with metal or cement. Modification of socket fixation resulted in improved clinical outcomes. With a press-fit metal shell and an alumina liner utilized for 10 years, the results are excellent especially in a young and active population. Alumina-on-alumina seems at the moment to be one of the best choices when a total hip arthroplasty has to be performed in young and active patients. PMID:11180930

  7. Tribological properties of structural ceramics

    NASA Technical Reports Server (NTRS)

    Buckley, Donald H.; Miyoshi, Kazuhisa

    1989-01-01

    The tribological and lubricated behavior of both oxide and nonoxide ceramics are reviewed in this chapter. Ceramics are examined in contact with themselves, other harder materials and metals. Elastic, plastic and fracture behavior of ceramics in solid state contact is discussed. The contact load necessary to initiate fracture in ceramics is shown to be appreciably reduced with tangential motion. Both friction and wear of ceramics are anisotropic and relate to crystal structure as has been observed with metals. Grit size effects in two and three body abrasive wear are observed for ceramics. Both free energy of oxide formation and the d valence bond character of metals are related to the friction and wear characteristics for metals in contact with ceramics. Surface contaminants affect friction and adhesive wear. For example, carbon on silicon carbide and chlorine on aluminum oxide reduce friction while oxygen on metal surfaces in contact with ceramics increases friction. Lubrication increases the critical load necessary to initiate fracture of ceramics both in indentation and with sliding or rubbing. Ceramics compositions both as coatings and in composites are described for the high temperature lubrication of both alloys and ceramics.

  8. Tribological properties of structural ceramics

    NASA Technical Reports Server (NTRS)

    Buckley, D. H.; Miyoshi, K.

    1985-01-01

    The tribological and lubricated behavior of both oxide and nonoxide ceramics are reviewed in this chapter. Ceramics are examined in contact with themselves, other harder materials and metals. Elastic, plastic and fracture behavior of ceramics in solid state contact is discussed. The contact load necessary to initiate fracture in ceramics is shown to be appreciably reduced with tangential motion. Both friction and wear of ceramics are anisotropic and relate to crystal structure as has been observed with metals. Grit size effects in two and three body abrasive wear are observed for ceramics. Both free energy of oxide formation and the d valence bond character of metals are related to the friction and wear characteristics for metals in contact with ceramics. Surface contaminants affect friction and adhesive wear. For example, carbon on silicon carbide and chlorine on aluminum oxide reduce friction while oxygen on metal surfaces in contact with ceramics increases friction. Lubrication increases the critical load necessary to initiate fracture of ceramics both in indentation and with sliding or rubbing. Ceramics compositions both as coatings and in composites are described for the high temperature lubrication of both alloys and ceramics.

  9. Light-weight ceramic insulation

    NASA Technical Reports Server (NTRS)

    Hsu, Ming-Ta S. (Inventor); Chen, Timothy S. (Inventor)

    2002-01-01

    Ultra-high temperature, light-weight, ceramic insulation such as ceramic tile is obtained by pyrolyzing a siloxane gel derived from the reaction of at least one organo dialkoxy silane and at least one tetralkoxy silane in an acid or base liquid medium. The reaction mixture of the tetra- and dialkoxy silanes may contain also an effective amount of a mono- or trialkoxy silane to obtain the siloxane gel. The siloxane gel is dried at ambient pressures to form a siloxane ceramic precursor without significant shrinkage. The siloxane ceramic precursor is subsequently pyrolyzed, in an inert atmosphere, to form the black ceramic insulation comprising atoms of silicon, carbon and oxygen. The ceramic insulation, can be characterized as a porous, uniform ceramic tile resistant to oxidation at temperatures ranging as high as 1700.degree. C. and is particularly useful as lightweight tiles for spacecraft and other high-temperature insulation applications.

  10. Metal to ceramic sealed joint

    DOEpatents

    Lasecki, J.V.; Novak, R.F.; McBride, J.R.

    1991-08-27

    A metal to ceramic sealed joint which can withstand wide variations in temperature and maintain a good seal is provided for use in a device adapted to withstand thermal cycling from about 20 to about 1000 degrees C. The sealed joint includes a metal member, a ceramic member having an end portion, and an active metal braze forming a joint to seal the metal member to the ceramic member. The joint is positioned remote from the end portion of the ceramic member to avoid stresses at the ends or edges of the ceramic member. The sealed joint is particularly suited for use to form sealed metal to ceramic joints in a thermoelectric generator such as a sodium heat engine where a solid ceramic electrolyte is joined to metal parts in the system. 11 figures.

  11. Metal to ceramic sealed joint

    DOEpatents

    Lasecki, John V.; Novak, Robert F.; McBride, James R.

    1991-01-01

    A metal to ceramic sealed joint which can withstand wide variations in temperature and maintain a good seal is provided for use in a device adapted to withstand thermal cycling from about 20 to about 1000 degrees C. The sealed joint includes a metal member, a ceramic member having an end portion, and an active metal braze forming a joint to seal the metal member to the ceramic member. The joint is positioned remote from the end portion of the ceramic member to avoid stresses at the ends or edges of the ceramic member. The sealed joint is particularly suited for use to form sealed metal to ceramic joints in a thermoelectric generator such as a sodium heat engine where a solid ceramic electrolyte is joined to metal parts in the system.

  12. Coated ceramic breeder materials

    DOEpatents

    Tam, Shiu-Wing; Johnson, Carl E.

    1987-04-07

    A breeder material for use in a breeder blanket of a nuclear reactor is disclosed. The breeder material comprises a core material of lithium containing ceramic particles which has been coated with a neutron multiplier such as Be or BeO, which coating has a higher thermal conductivity than the core material.

  13. OXYGEN TRANSPORT CERAMIC MEMBRANES

    SciTech Connect

    Dr. Sukumar Bandopadhyay; Dr. Nagendra Nagabhushana

    2001-05-01

    The mechanical properties of model systems were analyzed. A reasonably accurate finite element model was implemented and a rational metric to predict the strength of ceramic/metal concentrical joints was developed. The mode of failure of the ceramic/metal joints was determined and the importance of the mechanical properties of the braze material was assessed. Thermal cycling experiments were performed on the model systems and the results were discussed. Additionally, experiments using the concept of placing diffusion barriers on the ceramic surface to limit the extent of the reaction with the braze were performed. It was also observed that the nature and morphology of the reaction zone depends greatly on the nature of the perovskite structure being used. From the experiments, it is observed that the presence of Cr in the Fe-occupied sites decreases the tendency of Fe to segregate and to precipitate out of the lattice. In these new experiments, Ni was observed to play a major role in the decomposition of the ceramic substrate.

  14. Refractory ceramic fibers

    Integrated Risk Information System (IRIS)

    Refractory ceramic fibers ; CASRN Not found Human health assessment information on a chemical substance is included in the IRIS database only after a comprehensive review of toxicity data , as outlined in the IRIS assessment development process . Sections I ( Health Hazard Assessments for Noncarcino

  15. Microwave processing of ceramics

    SciTech Connect

    Katz, J.D.

    1993-01-01

    Recent work in the areas of microwave processing and joining of ceramics is briefly reviewed. Advantages and disadvantages of microwave processing as well as some of the current issues in the field are discussed. Current state and potential for future commercialization of this technology is also addressed.

  16. Microwave processing of ceramics

    SciTech Connect

    Katz, J.D.

    1993-04-01

    Recent work in the areas of microwave processing and joining of ceramics is briefly reviewed. Advantages and disadvantages of microwave processing as well as some of the current issues in the field are discussed. Current state and potential for future commercialization of this technology is also addressed.

  17. Microporous alumina ceramic membranes

    DOEpatents

    Anderson, M.A.; Guangyao Sheng.

    1993-05-04

    Several methods are disclosed for the preparation microporous alumina ceramic membranes. For the first time, porous alumina membranes are made which have mean pore sizes less than 100 Angstroms and substantially no pores larger than that size. The methods are based on improved sol-gel techniques.

  18. Microporous alumina ceramic membranes

    DOEpatents

    Anderson, Marc A.; Sheng, Guangyao

    1993-01-01

    Several methods are disclosed for the preparation microporous alumina ceramic membranes. For the first time, porous alumina membranes are made which have mean pore sizes less than 100 Angstroms and substantially no pores larger than that size. The methods are based on improved sol-gel techniques.

  19. OXYGEN TRANSPORT CERAMIC MEMBRANES

    SciTech Connect

    Dr. Sukumar Bandopadhyay; Dr. Nagendfra Nagabhushana

    2001-07-01

    The mechanical properties of model systems were analyzed. A reasonably accurate finite element model was implemented and a rational metric to predict the strength of ceramic/metal concentrical joints was developed. The mode of failure of the ceramic/metal joints was determined and the importance of the mechanical properties of the braze material was assessed. Thermal cycling experiments were performed on the model systems and the results were discussed. Additionally, experiments using the concept of placing diffusion barriers on the ceramic surface to limit the extent of the reaction with the braze were performed. It was also observed that the nature and morphology of the reaction zone depends greatly on the nature of the perovskite structure being used. From the experiments, it is observed that the presence of Cr in the Fe-occupied sites decreases the tendency of Fe to segregate and to precipitate out of the lattice. In these new experiments, Ni was observed to play a major role in the decomposition of the ceramic substrate.

  20. Silicon carbide ceramic production

    NASA Technical Reports Server (NTRS)

    Suzuki, K.; Shinohara, N.

    1984-01-01

    A method to produce sintered silicon carbide ceramics in which powdery carbonaceous components with a dispersant are mixed with silicon carbide powder, shaped as required with or without drying, and fired in nonoxidation atmosphere is described. Carbon black is used as the carbonaceous component.

  1. Facilitated transport of copper with hydroxyapatite nanoparticles in saturated sand

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Saturated packed column experiments were conducted to investigate the facilitated transport of Cu with hydroxyapatite nanoparticles (nHAP) at different pore water velocities (0.22-2.2 cm min–1), solution pH (6.2-9.0), and fraction of Fe oxide coating on grain surfaces (', 0-0.36). The facilitated tr...

  2. Peculiarities of hydroxyapatite/nanodiamond composites as novel implants

    NASA Astrophysics Data System (ADS)

    Pramatarova, L.; Dimitrova, R.; Pecheva, E.; Spassov, T.; Dimitrova, M.

    2007-12-01

    Hydroxyapatite/detonation nanodiamond composites are created on silica glass and cover glass by simple soaking process in an open deposition type set-up. The supersaturated solution (simulated body fluid, SBF) is prepared in a way to resemble the composition of human blood plasma. The composite growth is carried out through the addition of detonation nanodiamond particles to the SBF. Scanning electron microscopy, X-ray diffraction and FTIR spectroscopy are used to determine the surface morphology and the structure of the hydroxyapatite /detonation nanodiamond composite layers. The applied methods provide evidence that the nanodiamond surface functional groups interact strongly with the biological solution. The detonation nanodiamond surface is chemically multifunctional (surface OH, C-O-H, C = C, C-O-C and C = O groups exist), so that the hydroxyapatite is grown both by physical adsorption and chemical interaction. The OH- groups are regarded to play an important role in the hydroxyapatite growth on a diamond's surface from SBF, as they charge it negatively and attract Ca2+ ions, which in turn attract PO43- ions, thus forming apatite nuclei.

  3. Electrophoretic deposition of zinc-substituted hydroxyapatite coatings.

    PubMed

    Sun, Guangfei; Ma, Jun; Zhang, Shengmin

    2014-06-01

    Zinc-substituted hydroxyapatite nanoparticles synthesized by the co-precipitation method were used to coat stainless steel plates by electrophoretic deposition in n-butanol with triethanolamine as a dispersant. The effect of zinc concentration in the synthesis on the morphology and microstructure of coatings was investigated. It is found that the deposition current densities significantly increase with the increasing zinc concentration. The zinc-substituted hydroxyapatite coatings were analyzed by X-ray diffraction, scanning electron microscopy and Fourier transform infrared spectroscopy. It is inferred that hydroxyapatite and triethanolamine predominate in the chemical composition of coatings. With the increasing Zn/Ca ratios, the contents of triethanolamine decrease in the final products. The triethanolamine can be burnt out by heat treatment. The tests of adhesive strength have confirmed good adhesion between the coatings and substrates. The formation of new apatite layer on the coatings has been observed after 7days of immersion in a simulated body fluid. In summary, the results show that dense, uniform zinc-substituted hydroxyapatite coatings are obtained by electrophoretic deposition when the Zn/Ca ratio reaches 5%. PMID:24863199

  4. Accelerated Nucleation of Hydroxyapatite Using an Engineered Hydrophobin Fusion Protein.

    PubMed

    Melcher, Melanie; Facey, Sandra J; Henkes, Thorsten M; Subkowski, Thomas; Hauer, Bernhard

    2016-05-01

    Calcium phosphate mineralization is of particular interest in dental repair. A biomimetic approach using proteins or peptides is a highly promising way to reconstruct eroded teeth. In this study, the screening of several proteins is described for their binding and nucleating activities toward hydroxyapatite. Out of 27 tested candidates, only two hydrophobin fusion proteins showed binding abilities to hydroxyapatite in a mouthwash formulation and an increased nucleation in artificial saliva. Using a semirational approach, one of the two candidates (DEWA_5), a fusion protein consisting of a truncated section of the Bacillus subtilis synthase YaaD, the Aspergillus nidulans hydrophobin DEWA, and the rationally designed peptide P11-4 described in the literature, could be further engineered toward a faster mineral formation. The variants DEWA_5a (40aaYaaD-SDSDSD-DEWA) and DEWA_5b (40aaYaaD-RDRDRD-DEWA) were able to enhance the nucleation activity without losing the ability to form hydroxyapatite. In the case of variant DEWA_5b, an additional increase in the binding toward hydroxyapatite could be achieved. Especially with the variant DEWA_5a, the protein engineering of the rationally designed peptide sequence resulted in a resemblance of an amino acid motif that is found in nature. The engineered peptide resembles the amino acid motif in dentin phosphoprotein, one of the major proteins involved in dentinogenesis. PMID:27010648

  5. Periodontal regeneration with stem cells-seeded collagen-hydroxyapatite scaffold.

    PubMed

    Liu, Zeping; Yin, Xing; Ye, Qingsong; He, Wulin; Ge, Mengke; Zhou, Xiaofu; Hu, Jing; Zou, Shujuan

    2016-07-01

    Re-establishing compromised periodontium to its original structure, properties and function is demanding, but also challenging, for successful orthodontic treatment. In this study, the periodontal regeneration capability of collagen-hydroxyapatite scaffolds, seeded with bone marrow stem cells, was investigated in a canine labial alveolar bone defect model. Bone marrow stem cells were isolated, expanded and characterized. Porous collagen-hydroxyapatite scaffold and cross-linked collagen-hydroxyapatite scaffold were prepared. Attachment, migration, proliferation and morphology of bone marrow stem cells, co-cultured with porous collagen-hydroxyapatite or cross-linked collagen-hydroxyapatite, were evaluated in vitro. The periodontal regeneration capability of collagen-hydroxyapatite scaffold with or without bone marrow stem cells was tested in six beagle dogs, with each dog carrying one sham-operated site as healthy control, and three labial alveolar bone defects untreated to allow natural healing, treated with bone marrow stem cells - collagen-hydroxyapatite scaffold implant or collagen-hydroxyapatite scaffold implant, respectively. Animals were euthanized at 3 and 6 months (3 animals per group) after implantation and the resected maxillary and mandibular segments were examined using micro-computed tomography scan, H&E staining, Masson's staining and histometric evaluation. Bone marrow stem cells were successfully isolated and demonstrated self-renewal and multi-potency in vitro. The porous collagen-hydroxyapatite and cross-linked collagen-hydroxyapatite had average pore sizes of 415 ± 20 µm and 203 ± 18 µm and porosity of 69 ± 0.5% and 50 ± 0.2%, respectively. The attachment, proliferation and migration of bone marrow stem cells were satisfactory on both porous collagen-hydroxyapatite and cross-linked collagen-hydroxyapatite scaffolds. Implantation of bone marrow stem cells - collagen-hydroxyapatite or collagen-hydroxyapatite scaffold in

  6. Ceramic Laser Materials

    SciTech Connect

    Soules, T F; Clapsaddle, B J; Landingham, R L; Schaffers, K I

    2005-02-15

    Transparent ceramic materials have several major advantages over single crystals in laser applications, not the least of which is the ability to make large aperture parts in a robust manufacturing process. After more than a decade of working on making transparent YAG:Nd, Japanese workers have recently succeeded in demonstrating samples that performed as laser gain media as well as their single crystal counterparts. Since then several laser materials have been made and evaluated. For these reasons, developing ceramic laser materials is the most exciting and futuristic materials topic in today's major solid-state laser conferences. We have established a good working relationship with Konoshima Ltd., the Japanese producer of the best ceramic laser materials, and have procured and evaluated slabs designed by us for use in our high-powered SSHCL. Our measurements indicate that these materials will work in the SSHCL, and we have nearly completed retrofitting the SSHCL with four of the largest transparent ceramic YAG:Nd slabs in existence. We have also begun our own effort to make this material and have produced samples with various degrees of transparency/translucency. We are in the process of carrying out an extensive design-of-experiments to establish the significant process variables for making transparent YAG. Finally because transparent ceramics afford much greater flexibility in the design of lasers, we have been exploring the potential for much larger apertures, new materials, for example for the Mercury laser, other designs for SSHL, such as, edge pumping designs, slabs with built in ASE suppression, etc. This work has just beginning.

  7. Ceramic tubesheet design analysis

    SciTech Connect

    Mallett, R.H.; Swindeman, R.W.

    1996-06-01

    A transport combustor is being commissioned at the Southern Services facility in Wilsonville, Alabama to provide a gaseous product for the assessment of hot-gas filtering systems. One of the barrier filters incorporates a ceramic tubesheet to support candle filters. The ceramic tubesheet, designed and manufactured by Industrial Filter and Pump Manufacturing Company (EF&PM), is unique and offers distinct advantages over metallic systems in terms of density, resistance to corrosion, and resistance to creep at operating temperatures above 815{degrees}C (1500{degrees}F). Nevertheless, the operational requirements of the ceramic tubesheet are severe. The tubesheet is almost 1.5 m in (55 in.) in diameter, has many penetrations, and must support the weight of the ceramic filters, coal ash accumulation, and a pressure drop (one atmosphere). Further, thermal stresses related to steady state and transient conditions will occur. To gain a better understanding of the structural performance limitations, a contract was placed with Mallett Technology, Inc. to perform a thermal and structural analysis of the tubesheet design. The design analysis specification and a preliminary design analysis were completed in the early part of 1995. The analyses indicated that modifications to the design were necessary to reduce thermal stress, and it was necessary to complete the redesign before the final thermal/mechanical analysis could be undertaken. The preliminary analysis identified the need to confirm that the physical and mechanical properties data used in the design were representative of the material in the tubesheet. Subsequently, few exploratory tests were performed at ORNL to evaluate the ceramic structural material.

  8. Ceramic oxide powders and the formation thereof

    DOEpatents

    Katz, J.L.; Chenghung Hung.

    1993-12-07

    Ceramic oxide powders and a method for their preparation. Ceramic oxide powders are obtained using a flame process whereby two or more precursors of ceramic oxides are introduced into a counterflow diffusion flame burner wherein said precursors are converted into ceramic oxide powders. The morphology, particle size, and crystalline form of the ceramic oxide powders are determined by process conditions. 14 figures.

  9. Ceramic oxide powders and the formation thereof

    DOEpatents

    Katz, Joseph L.; Hung, Cheng-Hung

    1993-01-01

    Ceramic oxide powders and a method for their preparation. Ceramic oxide powders are obtained using a flame process whereby two or more precursors of ceramic oxides are introduced into a counterflow diffusion flame burner wherein said precursors are converted into ceramic oxide powders. The morphology, particle size, and crystalline form of the ceramic oxide powders are determined by process conditions.

  10. The inhibition of lamellar hydroxyapatite and lamellar magnetic hydroxyapatite on the migration and adhesion of breast cancer cells.

    PubMed

    Jin, Jun; Zuo, Guifu; Xiong, Guangyao; Luo, Honglin; Li, Qiuping; Ma, Chunying; Li, Deying; Gu, Feng; Ma, Yongjie; Wan, Yizao

    2014-04-01

    Hydroxyapatite nanoparticles have been reported to exhibit potent anti-tumor effects in some cancer cells. In our previous study, we have successfully synthesized two types of hydroxyapatite nanoparticles, laminated hydroxyapatite (L-HAp) and laminated magnetic hydroxyapatite (LM-HAp). In this study, we wanted to investigate the effects of L-HAp and LM-HAp with various concentrations on human breast cancer MDA-MB-231 cells. Cell proliferation was assessed with a MTT colorimetric assay. Scratch and adhesion assays were used to detect the effects of these two materials on migration and adhesion. The expressions of integrin β1 and Akt were measured by Western blotting. Our results showed that L-HAp and LM-HAp had little cell cytotoxicity and significantly reduced cell mobility and adhesion. LM-HAp showed greater inhibitor ability on migration and adhesion of MDA-MB-231 cells. Moreover, results from western blotting showed that L-HAp and LM-HAp impacted the phosphorylation of integrin β1, but showed no regular impact on Akt. This study suggests that L-HAp and LM-HAp may be potential anti-tumor and delivery system for breast cancer therapy. PMID:24363068

  11. Oxidation and Corrosion of Ceramics and Ceramic Matrix Composites

    NASA Technical Reports Server (NTRS)

    Jacobson, Nathan S.; Opila, Elizabeth J.; Lee, Kang N.

    2000-01-01

    Ceramics and ceramic matrix composites are candidates for numerous applications in high temperature environments with aggressive gases and possible corrosive deposits. There is a growing realization that high temperature oxidation and corrosion issues must be considered. There are many facets to these studies, which have been extensively covered in some recent reviews. The focus of this paper is on current research, over the past two years. In the authors' view, the most important oxidation and corrosion studies have focused on four major areas during this time frame. These are; (I) Oxidation of precursor-based ceramics; (II) Studies of the interphase material in ceramic matrix composites; (III) Water vapor interactions with ceramics, particularly in combustion environments; and (IV) Development of refractory oxide coatings for silicon-based ceramics. In this paper, we shall explore the most current work in each of these areas.

  12. Ceramic Stereolithography: Additive Manufacturing for Ceramics by Photopolymerization

    NASA Astrophysics Data System (ADS)

    Halloran, John W.

    2016-07-01

    Ceramic stereolithography and related additive manufacturing methods involving photopolymerization of ceramic powder suspensions are reviewed in terms of the capabilities of current devices. The practical fundamentals of the cure depth, cure width, and cure profile are related to the optical properties of the monomer, ceramic, and photo-active components. Postpolymerization steps, including harvesting and cleaning the objects, binder burnout, and sintering, are discussed and compared with conventional methods. The prospects for practical manufacturing are discussed.

  13. Integrally cored ceramic investment casting mold fabricated by ceramic stereolithography

    NASA Astrophysics Data System (ADS)

    Bae, Chang-Jun

    Superalloy airfoils are produced by investment casting (IC), which uses ceramic cores and wax patterns with ceramic shell molds. Hollow cored superalloy airfoils in a gas turbine engine are an example of complex IC parts. The complex internal hollow cavities of the airfoil are designed to conduct cooling air through one or more passageways. These complex internal passageways have been fabricated by a lost wax process requiring several processing steps; core preparation, injection molding for wax pattern, and dipping process for ceramic shell molds. Several steps generate problems such as high cost and decreased accuracy of the ceramic mold. For example, costly tooling and production delay are required to produce mold dies for complex cores and wax patterns used in injection molding, resulting in a big obstacle for prototypes and smaller production runs. Rather than using separate cores, patterns, and shell molds, it would be advantageous to directly produce a mold that has the casting cavity and the ceramic core by one process. Ceramic stereolithography (CerSLA) can be used to directly fabricate the integrally cored ceramic casting mold (ICCM). CerSLA builds ceramic green objects from CAD files from many thin liquid layers of powder in monomer, which are solidified by polymerization with a UV laser, thereby "writing" the design for each slice. This dissertation addresses the integrally cored casting ceramic mold (ICCM), the ceramic core with a ceramic mold shell in a single patternless construction, fabricated by ceramic stereolithography (CerSLA). CerSLA is considered as an alternative method to replace lost wax processes, for small production runs or designs too complex for conventional cores and patterns. The main topic is the development of methods to successfully fabricate an ICCM by CerSLA from refractory silica, as well as related issues. The related issues are the segregation of coarse fused silica powders in a layer, the degree of segregation parameter to

  14. Synthesis of nano-bioactive glass-ceramic powders and its in vitro bioactivity study in bovine serum albumin protein

    NASA Astrophysics Data System (ADS)

    Nabian, Nima; Jahanshahi, Mohsen; Rabiee, Sayed Mahmood

    2011-07-01

    Bioactive glasses and ceramics have proved to be able to chemically bond to living bone due to the formation of an apatite-like layer on its surface. The aim of this work was preparation and characterization of bioactive glass-ceramic by sol-gel method. Nano-bioglass-ceramic material was crushed into powder and its bioactivity was examined in vitro with respect to the ability of hydroxyapatite layer to form on the surface as a result of contact with bovine serum albumin (BSA) protein. The obtained nano-bioactive glass-ceramic was analyzed before and after contact with BSA solution. This study used scanning electron microscope (SEM), transmission electron microscope (TEM), X-ray powder diffraction (XRD) and Fourier transform infrared spectroscopy (FTIR) analysis to examine its morphology, crystallinity and composition. The TEM images showed that the NBG particles size were 10-40 nm. Bioactivity of nanopowder was confirmed by SEM and XRD due to the presence of a rich bone-like apatite layer. Therefore, this nano-BSA-bioglass-ceramic composite material is promising for medical applications such as bone substitutes and drug carriers.

  15. Positron annihilation in transparent ceramics

    NASA Astrophysics Data System (ADS)

    Husband, P.; Bartošová, I.; Slugeň, V.; Selim, F. A.

    2016-01-01

    Transparent ceramics are emerging as excellent candidates for many photonic applications including laser, scintillation and illumination. However achieving perfect transparency is essential in these applications and requires high technology processing and complete understanding for the ceramic microstructure and its effect on the optical properties. Positron annihilation spectroscopy (PAS) is the perfect tool to study porosity and defects. It has been applied to investigate many ceramic structures; and transparent ceramics field may be greatly advanced by applying PAS. In this work positron lifetime (PLT) measurements were carried out in parallel with optical studies on yttrium aluminum garnet transparent ceramics in order to gain an understanding for their structure at the atomic level and its effect on the transparency and light scattering. The study confirmed that PAS can provide useful information on their microstructure and guide the technology of manufacturing and advancing transparent ceramics.

  16. Ceramic hot-gas filter

    DOEpatents

    Connolly, E.S.; Forsythe, G.D.; Domanski, D.M.; Chambers, J.A.; Rajendran, G.P.

    1999-05-11

    A ceramic hot-gas candle filter is described having a porous support of filament-wound oxide ceramic yarn at least partially surrounded by a porous refractory oxide ceramic matrix, and a membrane layer on at least one surface thereof. The membrane layer may be on the outer surface, the inner surface, or both the outer and inner surface of the porous support. The membrane layer may be formed of an ordered arrangement of circularly wound, continuous filament oxide ceramic yarn, a ceramic filler material which is less permeable than the filament-wound support structure, or some combination of continuous filament and filler material. A particularly effective membrane layer features circularly wound filament with gaps intentionally placed between adjacent windings, and a filler material of ceramic particulates uniformly distributed throughout the gap region. The filter can withstand thermal cycling during back pulse cleaning and is resistant to chemical degradation at high temperatures.

  17. Ceramic hot-gas filter

    DOEpatents

    Connolly, Elizabeth Sokolinski; Forsythe, George Daniel; Domanski, Daniel Matthew; Chambers, Jeffrey Allen; Rajendran, Govindasamy Paramasivam

    1999-01-01

    A ceramic hot-gas candle filter having a porous support of filament-wound oxide ceramic yarn at least partially surrounded by a porous refractory oxide ceramic matrix, and a membrane layer on at least one surface thereof. The membrane layer may be on the outer surface, the inner surface, or both the outer and inner surface of the porous support. The membrane layer may be formed of an ordered arrangement of circularly wound, continuous filament oxide ceramic yarn, a ceramic filler material which is less permeable than the filament-wound support structure, or some combination of continuous filament and filler material. A particularly effective membrane layer features circularly wound filament with gaps intentionally placed between adjacent windings, and a filler material of ceramic particulates uniformly distributed throughout the gap region. The filter can withstand thermal cycling during backpulse cleaning and is resistant to chemical degradation at high temperatures.

  18. Laser machining of ceramic

    SciTech Connect

    Laudel, A.

    1980-01-01

    The Kansas City Division of The Bendix Corporation manufactures hybrid microcircuits (HMCs) using both thin film and thick film technologies. Laser machining is used to contour the ceramic substrates and to drill holes in the ceramic for frontside-backside interconnections (vias) and holes for mounting components. A 1000 W CO/sub 2/ type laser is used. The laser machining process, and methods used for removing protruding debris and debris from holes, for cleaning the machined surfaces, and for refiring are described. The laser machining process described consistently produces vias, component holes and contours with acceptable surface quality, hole locations, diameter, flatness and metallization adhesion. There are no cracks indicated by dipping in fluorescent dye penetrant and the substances are resistant to repeated thermal shock.

  19. Ceramic composite coating

    DOEpatents

    Wicks, George G.

    1997-01-01

    A thin, room-temperature-curing, ceramic composite for coating and patching etal substrates comprises a sol gel silica glass matrix filled with finely ground particles or fibers, preferably alumina. The sol gel glass is made by adding ethanol to water to form a first mixture, then separately adding ethanol to tetraethyl orthosilicate to form a second mixture, then slowly adding the first to the second mixture to make a third mixture, and making a slurry by adding the finely ground particles or fibers to the third mixture. The composite can be applied by spraying, brushing or trowelling. If applied to patch fine cracks, densification of the ceramic composite may be obtained to enhance sealing by applying heat during curing.

  20. Ceramic composite coating

    DOEpatents

    Wicks, G.G.

    1997-01-21

    A thin, room-temperature-curing, ceramic composite for coating and patching metal substrates comprises a sol gel silica glass matrix filled with finely ground particles or fibers, preferably alumina. The sol gel glass is made by adding ethanol to water to form a first mixture, then separately adding ethanol to tetraethyl orthosilicate to form a second mixture, then slowly adding the first to the second mixture to make a third mixture, and making a slurry by adding the finely ground particles or fibers to the third mixture. The composite can be applied by spraying, brushing or trowelling. If applied to patch fine cracks, densification of the ceramic composite may be obtained to enhance sealing by applying heat during curing.

  1. Laser in Ceramics Processing

    NASA Astrophysics Data System (ADS)

    Lal, Bajrang; Jain, Pankaj

    LASER, an acronym for Light Amplification by Stimulated Emission of Radiation have unique properties, Which make it differ from ordinary light such as it is highly coherent, monochromatic, negligible divergence and scattering loss and a intense beam of electromagnetic radiation or light. It also occur in a wide range of wavelength/frequency (from Ultraviolet to Infrared), energy/power and beam-mode/configurations ; Due to these unique properties, it have use in wide application of ceramic processing for industrial manufacturing, fabrication of electronic circuit such as marking, serializing, engraving, cutting, micro-structuring because laser only produces localized heating, without any contact and thermal stress on the any part during processing. So there is no risk of fracturing that occurs during mechanical sawing and also reduce Cost of processing. The discussion in this paper highlight the application of laser in ceramics processing.

  2. Ceramics for fusion applications

    SciTech Connect

    Clinard, F.W. Jr.

    1986-01-01

    Ceramics are required for a variety of uses in both near-term fusion devices and in commercial powerplants. These materials must retain adequate structural and electrical properties under conditions of neutron, particle, and ionizing irradiation; thermal and applied stresses; and physical and chemical sputtering. Ceramics such as Al/sub 2/O/sub 3/, MgAl/sub 2/O/sub 4/, BeO, Si/sub 3/N/sub 4/ and SiC are currently under study for fusion applications, and results to date show widely-varying response to the fusion environment. Materials can be identified today which will meet initial operating requirements, but improvements in physical properties are needed to achieve satisfactory lifetimes for critical applications.

  3. Ceramic Composite Thin Films

    NASA Technical Reports Server (NTRS)

    Ruoff, Rodney S. (Inventor); Stankovich, Sasha (Inventor); Dikin, Dmitriy A. (Inventor); Nguyen, SonBinh T. (Inventor)

    2013-01-01

    A ceramic composite thin film or layer includes individual graphene oxide and/or electrically conductive graphene sheets dispersed in a ceramic (e.g. silica) matrix. The thin film or layer can be electrically conductive film or layer depending the amount of graphene sheets present. The composite films or layers are transparent, chemically inert and compatible with both glass and hydrophilic SiOx/silicon substrates. The composite film or layer can be produced by making a suspension of graphene oxide sheet fragments, introducing a silica-precursor or silica to the suspension to form a sol, depositing the sol on a substrate as thin film or layer, at least partially reducing the graphene oxide sheets to conductive graphene sheets, and thermally consolidating the thin film or layer to form a silica matrix in which the graphene oxide and/or graphene sheets are dispersed.

  4. Seal between metal and ceramic conduits

    DOEpatents

    Underwood, Richard Paul; Tentarelli, Stephen Clyde

    2015-02-03

    A seal between a ceramic conduit and a metal conduit of an ion transport membrane device consisting of a sealing surface of ceramic conduit, a sealing surface of ceramic conduit, a single gasket body, and a single compliant interlayer.

  5. Multifracture of ceramic composites

    SciTech Connect

    Weitsman, Y.J.; Zhu, H.

    1992-03-01

    This work presents a mechanistic model for the multifracture process of uniaxially reinforced fibrous ceramic composites under monotonically increasing tension parallel to the fiber direction. The model employs an energy criterion to account for the progression of matrix cracks, bridged by intact fibers, and Weibull failure statistics to relate the failure of the fibers. Consideration is given to the interactions between the foregoing failure processes as well as to the effects of various material parameters on the response of the composite.

  6. Microprobes aluminosilicate ceramic membranes

    DOEpatents

    Anderson, Marc A.; Sheng, Guangyao

    1993-01-01

    Methods have been developed to make mixed alumina-silicate and aluminosilicate particulate microporous ceramic membranes. One method involves the making of separate alumina and silica sols which are then mixed. Another method involves the creation of a combined sol with aluminosilicate particles. The resulting combined alumina and silica membranes have high surface area, a very small pore size, and a very good temperature stability.

  7. Miniature ceramic fuel cell

    DOEpatents

    Lessing, Paul A.; Zuppero, Anthony C.

    1997-06-24

    A miniature power source assembly capable of providing portable electricity is provided. A preferred embodiment of the power source assembly employing a fuel tank, fuel pump and control, air pump, heat management system, power chamber, power conditioning and power storage. The power chamber utilizes a ceramic fuel cell to produce the electricity. Incoming hydro carbon fuel is automatically reformed within the power chamber. Electrochemical combustion of hydrogen then produces electricity.

  8. Joined ceramic product

    DOEpatents

    Henager, Jr., Charles W [Kennewick, WA; Brimhall, John L [West Richland, WA

    2001-08-21

    According to the present invention, a joined product is at least two ceramic parts, specifically bi-element carbide parts with a bond joint therebetween, wherein the bond joint has a metal silicon phase. The bi-element carbide refers to compounds of MC, M.sub.2 C, M.sub.4 C and combinations thereof, where M is a first element and C is carbon. The metal silicon phase may be a metal silicon carbide ternary phase, or a metal silicide.

  9. Superplastic forging nitride ceramics

    DOEpatents

    Panda, Prakash C.; Seydel, Edgar R.; Raj, Rishi

    1988-03-22

    The invention relates to producing relatively flaw free silicon nitride ceramic shapes requiring little or no machining by superplastic forging This invention herein was made in part under Department of Energy Grant DE-AC01-84ER80167, creating certain rights in the United States Government. The invention was also made in part under New York State Science and Technology Grant SB1R 1985-10.

  10. OXYGEN TRANSPORT CERAMIC MEMBRANES

    SciTech Connect

    Dr. Sukumar Bandopadhyay; Dr. Nagendra Nagabhushana

    2001-12-01

    Conversion of natural gas to liquid fuels and chemicals is a major goal for the Nation as it enters the 21st Century. Technically robust and economically viable processes are needed to capture the value of the vast reserves of natural gas on Alaska's North Slope, and wean the Nation from dependence on foreign petroleum sources. Technologies that are emerging to fulfill this need are all based syngas as an intermediate. Syngas (a mixture of hydrogen and carbon monoxide) is a fundamental building block from which chemicals and fuels can be derived. Lower cost syngas translates directly into more cost-competitive fuels and chemicals. The currently practiced commercial technology for making syngas is either steam methane reforming (SMR) or a two-step process involving cryogenic oxygen separation followed by natural gas partial oxidation (POX). These high-energy, capital-intensive processes do not always produce syngas at a cost that makes its derivatives competitive with current petroleum-based fuels and chemicals. This project has the following 6 main tasks: Task 1--Design, fabricate and evaluate ceramic to metal seals based on graded ceramic powder/metal braze joints. Task 2--Evaluate the effect of defect configuration on ceramic membrane conductivity and long term chemical and structural stability. Task 3--Determine materials mechanical properties under conditions of high temperatures and reactive atmospheres. Task 4--Evaluate phase stability and thermal expansion of candidate perovskite membranes and develop techniques to support these materials on porous metal structures. Task 5--Assess the microstructure of membrane materials to evaluate the effects of vacancy-impurity association, defect clusters, and vacancy-dopant association on the membrane performance and stability. Task 6--Measure kinetics of oxygen uptake and transport in ceramic membrane materials under commercially relevant conditions using isotope labeling techniques.

  11. Tailored Ceramics for Laser Applications

    SciTech Connect

    Hollingsworth, Joel

    2007-12-10

    Transparent ceramics match or exceed the performance of single-crystal materials in laser applications, with a more-robust fabrication process. Controlling the distribution of optical dopants in transparent ceramics would allow qualitative improvements in amplifier slab design by allowing gain and loss to be varied within the material. My work aims to achieve a controlled pattern or gradient of dopant prior to sintering, in order to produce tailored ceramics.

  12. Testing Ceramics for Diesel Engines

    NASA Technical Reports Server (NTRS)

    Schneider, H. W.

    1985-01-01

    Adaptation of diesel engine allows prestressed ceramic materials evaluated under realistic pressure, temperature, and stress without introducing extraneous stress. Ceramic specimen part of prechamber of research engine. Specimen held in place by clamp, introduces required axial compressive stress. Specimen -- cylindrical shell -- surrounded by chamber vented or pressurized to introduce requisite radial stress in ceramic. Pressure chamber also serves as safety shield in case speimen disintegrates. Materials under consideration as cylinder liners for diesel engines.

  13. Processing method for superconducting ceramics

    DOEpatents

    Bloom, Ira D.; Poeppel, Roger B.; Flandermeyer, Brian K.

    1993-01-01

    A process for preparing a superconducting ceramic and particularly YBa.sub.2 Cu.sub.3 O.sub.7-.delta., where .delta. is in the order of about 0.1-0.4, is carried out using a polymeric binder which decomposes below its ignition point to reduce carbon residue between the grains of the sintered ceramic and a nonhydroxylic organic solvent to limit the problems with water or certain alcohols on the ceramic composition.

  14. Processing method for superconducting ceramics

    DOEpatents

    Bloom, Ira D.; Poeppel, Roger B.; Flandermeyer, Brian K.

    1993-02-02

    A process for preparing a superconducting ceramic and particularly YBa.sub.2 Cu.sub.3 O.sub.7-.delta., where .delta. is in the order of about 0.1-0.4, is carried out using a polymeric binder which decomposes below its ignition point to reduce carbon residue between the grains of the sintered ceramic and a nonhydroxylic organic solvent to limit the problems with water or certain alcohols on the ceramic composition.

  15. Ceramic stationary gas turbine

    SciTech Connect

    Roode, M. van

    1995-10-01

    The performance of current industrial gas turbines is limited by the temperature and strength capabilities of the metallic structural materials in the engine hot section. Because of their superior high-temperature strength and durability, ceramics can be used as structural materials for hot section components (blades, nozzles, combustor liners) in innovative designs at increased turbine firing temperatures. The benefits include the ability to increase the turbine inlet temperature (TIT) to about 1200{degrees}C ({approx}2200{degrees}F) or more with uncooled ceramics. It has been projected that fully optimized stationary gas turbines would have a {approx}20 percent gain in thermal efficiency and {approx}40 percent gain in output power in simple cycle compared to all metal-engines with air-cooled components. Annual fuel savings in cogeneration in the U.S. would be on the order of 0.2 Quad by 2010. Emissions reductions to under 10 ppmv NO{sub x} are also forecast. This paper describes the progress on a three-phase, 6-year program sponsored by the U.S. Department of Energy, Office of Industrial Technologies, to achieve significant performance improvements and emissions reductions in stationary gas turbines by replacing metallic hot section components with ceramic parts. Progress is being reported for the period September 1, 1994, through September 30, 1995.

  16. Ceramic stationary gas turbine

    SciTech Connect

    Roode, M. van

    1995-12-31

    The performance of current industrial gas turbines is limited by the temperature and strength capabilities of the metallic structural materials in the engine hot section. Because of their superior high-temperature strength and durability, ceramics can be used as structural materials for hot section components (blades, nozzles, combustor liners) in innovative designs at increased turbine firing temperatures. The benefits include the ability to increase the turbine inlet temperature (TIT) to about 1200{degrees}C ({approx}2200{degrees}F) or more with uncooled ceramics. It has been projected that fully optimized stationary gas turbines would have a {approx}20 percent gain in thermal efficiency and {approx}40 percent gain in output power in simple cycle compared to all metal-engines with air-cooled components. Annual fuel savings in cogeneration in the U.S. would be on the order of 0.2 Quad by 2010. Emissions reductions to under 10 ppmv NO{sub x} are also forecast. This paper describes the progress on a three-phase, 6-year program sponsored by the U.S. Department of Energy, Office of Industrial Technologies, to achieve significant performance improvements and emissions reductions in stationary gas turbines by replacing metallic hot section components with ceramic parts. Progress is being reported for the period September 1, 1994, through September 30, 1995.

  17. Outcomes following ossicular chain reconstruction with composite prostheses: hydroxyapatite-polyethylene vs. hydroxyapatite-titanium.

    PubMed

    Hahn, Yoav; Bojrab, Dennis I

    2013-06-01

    We conducted a retrospective study to compare the results of ossicular chain reconstruction (OCR) with two types of composite prosthesis: a hydroxyapatite-polyethylene (HAPEX) implant and a hydroxyapatite-titanium (HATi) prosthesis. We reviewed the records of 222 patients-104 males and 118 females, aged 8 to 79 years (mean: 39.7)-who had undergone OCR for ossicular chain dysfunction and who met our eligibility criteria. In addition to demographic data and the type of prosthesis, we compiled information on pre- and postoperative audiometric findings, the underlying diagnosis, the timing of surgery (primary, planned, or revision), the type of surgery (tympanoplasty alone, tympanoplasty with antrotomy, intact-canal-wall tympanomastoidectomy, or canal-wall-down tympanomastoidectomy), the extent of reconstruction (partial or total), the use of the malleus, the use of a tragal cartilage graft, and evidence of extrusion. Of the 222 patients, 46 had undergone insertion of either a partial (n = 36) or total (n = 10) ossicular replacement prosthesis (PORP and TORP, respectively) made with HAPEX, and 176 had received a PORP (n = 101) or TORP (n = 75) made with HATi. Postoperatively, the mean air-bone gap (ABG) was 14.0 dB in the HAPEX group and 14.7 dB in the HATi group, which was not a significant difference (p = 0.61). Postoperative success (ABG ≤20 dB) with PORP was obtained in 30 of the 36 patients in the HAPEX group (83.3%) and in 87 of the 101 patients in the HATi group (86.1%), while success with TORP was achieved in 7 of 10 HAPEX patients (70.0%) and 56 of 75 HATi patients (74.7%); there was no significant difference in either PORP or TORP success rates between the HAPEX and HATi groups (p = 0.32). A significantly better hearing result was obtained when the malleus was used in reconstruction (p = 0.035), but the use of tragal cartilage led to a significantly worse outcome (p = 0.026). Revision surgery was associated with a significantly worse postoperative result (p

  18. Polymer precursors for ceramic composites

    NASA Technical Reports Server (NTRS)

    Hurwitz, Frances I.

    1986-01-01

    The fiber composite approach to reinforced ceramics provides the possibility of achieving ceramics with high fracture toughness relative to monolithics. Fabrication of ceramic composites, however, demands low processing temperatures to avoid fiber degradation. Formation of complex shapes further requires small diameter fibers as well as techniques for infiltrating the matrix between fibers. Polymers offer low temperature processability, control of rheology not available with ceramic powders, and should serve as precursors to matrix fibers. In recent years, a number of polysilanes and polysilezanes were investigated as potential presursors. A review of candidate polymers is presented, including recent studies of silsesquioxanes.

  19. Production and thermal stability of pure and Cr3+ -doped hydroxyapatite

    NASA Astrophysics Data System (ADS)

    de Araujo, T. S.; de Souza, S. O.; de Sousa, E. M. B.; Araújo, M. S.

    2010-11-01

    Hydroxyapatite (HAP) have been used as starting material for biomedical applications. The pure and Cr3+ -doped hydroxyapatite were prepared by chemical precipitation reactions at 100, 500 e 800 °C in order to investigate the thermal stability of these materials. The characterization of the thermal behavior of this phosphate, especially on the structural changes with heating, is very important for production of sunscreens The powders were characterized using chemical analysis: X-ray diffraction (XRD) and thermal analysis. The present study was successful in the preparation of pure hydroxyapatite and chromium substituted hydroxyapatites with good thermal stability and nanoparticles formation.

  20. Structure of Biocompatible Coatings Produced from Hydroxyapatite Nanoparticles by Detonation Spraying

    NASA Astrophysics Data System (ADS)

    Nosenko, Valentyna; Strutynska, Nataliia; Vorona, Igor; Zatovsky, Igor; Dzhagan, Volodymyr; Lemishko, Sergiy; Epple, Matthias; Prymak, Oleg; Baran, Nikolai; Ishchenko, Stanislav; Slobodyanik, Nikolai; Prylutskyy, Yuriy; Klyui, Nickolai; Temchenko, Volodymyr

    2015-12-01

    Detonation-produced hydroxyapatite coatings were studied by scanning electron microscopy (SEM), X-ray powder diffraction (XRD), Raman spectroscopy, and electron paramagnetic resonance (EPR) spectroscopy. The source material for detonation spraying was a B-type carbonated hydroxyapatite powder. The coatings consisted of tetracalcium phosphate and apatite. The ratio depended slightly on the degree of crystallinity of the initial powder and processing parameters of the coating preparation. The tetracalcium phosphate phase was homogeneous; the apatite phase contained defects localized on the sixfold axis and consisted of hydroxyapatite and oxyapatite. Technological factors contributing to the transformation of hydroxyapatite powder structure during coating formation by detonation spraying are discussed.

  1. Development of lattice-inserted 5-Fluorouracil-hydroxyapatite nanoparticles as a chemotherapeutic delivery system.

    PubMed

    Tseng, Ching-Li; Chen, Jung-Chih; Wu, Yu-Chun; Fang, Hsu-Wei; Lin, Feng-Huei; Tang, Tzu-Piao

    2015-10-01

    Developing an effective vehicle for cancer treatment, hydroxyapatite nanoparticles were fabricated for drug delivery. When 5-Fluorouracil, a major chemoagent, is combined with hydroxyapatite nanocarriers by interclay insertion, the modified hydroxyapatite nanoparticles have superior lysosomal degradation profiles, which could be leveraged as controlled drug release. The decomposition of the hydroxyapatite nanocarriers facilitates the release of 5-Fluorouracil into the cytoplasm causing cell death. Hydroxyapatite nanoparticles with/without 5-Fluorouracil were synthesized and analyzed in this study. Their crystallization properties and chemical composition were examined by X-ray diffraction and Fourier transforms infrared spectroscopy. The 5-Fluorouracil release rate was determined by UV spectroscopy. The biocompatibility of hydroxyapatite-5-Fluorouracil extraction solution was assessed using 3T3 cells via a WST-8 assay. The effect of hydroxyapatite-5-Fluorouracil particles which directly work on the human lung adenocarcinoma (A549) cells was evaluated by a lactate dehydrogenase assay via contact cultivation. A 5-Fluorouracil-absorbed hydroxyapatite particles were also tested. Overall, hydroxyapatite-5-Fluorouracils were prepared using a co-precipitation method wherein 5-Fluorouracil was intercalated in the hydroxyapatite lattice as determined by X-ray diffraction. Energy dispersive scanning examination showed the 5-Fluorouracil content was higher in hydroxyapatite-5-Fluorouracil than in a prepared absorption formulation. With 5-Fluorouracil insertion in the lattice, the widths of the a and c axial constants of the hydroxyapatite crystal increased. The extraction solution of hydroxyapatite-5-Fluorouracil was nontoxic to 3T3 cells, in which 5-Fluorouracil was not released in a neutral phosphate buffer solution. In contrast, at a lower pH value (2.5), 5-Fluorouracil was released by the acidic decomposition of hydroxyapatite. Finally, the results of the lactate

  2. Structure of Biocompatible Coatings Produced from Hydroxyapatite Nanoparticles by Detonation Spraying.

    PubMed

    Nosenko, Valentyna; Strutynska, Nataliia; Vorona, Igor; Zatovsky, Igor; Dzhagan, Volodymyr; Lemishko, Sergiy; Epple, Matthias; Prymak, Oleg; Baran, Nikolai; Ishchenko, Stanislav; Slobodyanik, Nikolai; Prylutskyy, Yuriy; Klyui, Nickolai; Temchenko, Volodymyr

    2015-12-01

    Detonation-produced hydroxyapatite coatings were studied by scanning electron microscopy (SEM), X-ray powder diffraction (XRD), Raman spectroscopy, and electron paramagnetic resonance (EPR) spectroscopy. The source material for detonation spraying was a B-type carbonated hydroxyapatite powder. The coatings consisted of tetracalcium phosphate and apatite. The ratio depended slightly on the degree of crystallinity of the initial powder and processing parameters of the coating preparation. The tetracalcium phosphate phase was homogeneous; the apatite phase contained defects localized on the sixfold axis and consisted of hydroxyapatite and oxyapatite. Technological factors contributing to the transformation of hydroxyapatite powder structure during coating formation by detonation spraying are discussed. PMID:26625888

  3. On the assessment of hydroxyapatite fluoridation by means of Raman scattering

    SciTech Connect

    Campillo, M.; Valiente, M.; Lacharmoise, P. D.; Reparaz, J. S.; Goni, A. R.

    2010-06-28

    Hydroxyapatite is the main mineral component of bones and teeth. Fluorapatite, a bioceramic that can be obtained from hydroxyapatite by chemical substitution of the hydroxide ions with fluoride, exhibits lower mineral solubility and larger mechanical strength. Despite the widespread use of fluoride against caries, a reliable technique for unambiguous assessment of fluoridation in in vitro tests is still lacking. Here we present a method to probe fluorapatite formation in fluoridated hydroxyapatite by combining Raman scattering with thermal annealing. In synthetic minerals, we found that effectively fluoride substituted hydroxyapatite transforms into fluorapatite only after heat treatment, due to the high activation energy for this first order phase transition.

  4. Hydroxyapatite/poly(epsilon-caprolactone) double coating on magnesium for enhanced corrosion resistance and coating flexibility.

    PubMed

    Jo, Ji-Hoon; Li, Yuanlong; Kim, Sae-Mi; Kim, Hyoun-Ee; Koh, Young-Hag

    2013-11-01

    Hydroxyapatite was deposited on pure magnesium (Mg) with a flexible poly(ε-caprolactone) interlayer to reduce the corrosion rate of Mg and enhance coating flexibility. The poly(ε-caprolactone) interlayer was uniformly coated on Mg by a spraying method, followed by hydroxyapatite deposition on the poly(ε-caprolactone) using an aerosol deposition method. In scanning electron microscopy observations, inorganic/organic composite-like structure was observed between the hydroxyapatite and poly(ε-caprolactone) layers, resulting from the collisions of hydroxyapatite particles into the poly(ε-caprolactone) matrix at the initial stage of the aerosol deposition. The corrosion resistance of the coated Mg was examined using potentiodynamic polarization tests. The hydroxyapatite/poly(ε-caprolactone) double coating remarkably improved the corrosion resistance of Mg in Hank's solution. In the in vitro cell tests, the coated Mg showed better cell adhesion compared with the bare Mg due to the reduced corrosion rate and enhanced biocompatibility. The stability and flexibility of hydroxyapatite/poly(ε-caprolactone) double coating was investigated by scanning electron microscopy inspections after the coated Mg was deformed. The hydroxyapatite coating on the poly(ε-caprolactone) interlayer revealed enhanced coating stability and flexibility without cracking or delamination during bending and stretching compared with the hydroxyapatite single coating. These results demonstrated that the hydroxyapatite/poly(ε-caprolactone) double coating significantly improved the surface corrosion resistance of Mg and enhanced coating flexibility for use of Mg as a biodegradable implant. PMID:23241964

  5. On the assessment of hydroxyapatite fluoridation by means of Raman scattering

    NASA Astrophysics Data System (ADS)

    Campillo, M.; Lacharmoise, P. D.; Reparaz, J. S.; Goñi, A. R.; Valiente, M.

    2010-06-01

    Hydroxyapatite is the main mineral component of bones and teeth. Fluorapatite, a bioceramic that can be obtained from hydroxyapatite by chemical substitution of the hydroxide ions with fluoride, exhibits lower mineral solubility and larger mechanical strength. Despite the widespread use of fluoride against caries, a reliable technique for unambiguous assessment of fluoridation in in vitro tests is still lacking. Here we present a method to probe fluorapatite formation in fluoridated hydroxyapatite by combining Raman scattering with thermal annealing. In synthetic minerals, we found that effectively fluoride substituted hydroxyapatite transforms into fluorapatite only after heat treatment, due to the high activation energy for this first order phase transition.

  6. [FTIR and XRD analysis of hydroxyapatite from fossil human and animal teeth in Jinsha Relict, Chengdu].

    PubMed

    Huang, Cheng-min; Zhang, Qing; Bai, Song; Wang, Cheng-shan

    2007-12-01

    Diagenetic effect during burial on the hydroxyapatite in enamel and dentin from fossil human and animal teeth was examined, using X-ray diffraction (XRD) and Fourier transform infrared spectroscopy (FTIR). For the enamel and dentin of all fossil teeth, XRD patterns exhibit bulge line and overlap between major reflections of hydroxyapatite, and the crystallinity of hydroxyapatite is low. For each infrared spectrum, H2O and OH(-) have distinct peaks of absorbance, and PO4(3-) and CO3(2-) ions have intensive infrared vibration modes at the fundamental wave numbers. The component of hydroxyapatite of all fossil teeth is similar to the modern biological hydroxyapatite. Furthermore, the index (PCI) which reflects the hydroxyapatite crystallinity of each sample ranges from 2.4 to 4.0 while the index (BPI) reflecting the amount of type B carbonate to phosphate indicates that the values of CO3(2-) content in hydroxyapatite are rather high, accordingly the crystallinity of all fossil hydroxyapatites are poor. It could be concluded that little alteration of hydroxyapatites from fossil human and animal teeth occurred in the process of diagenesis in Jinsha Relict, Chengdu, China. PMID:18330282

  7. Sintering Effects on Morphology, Thermal Stability and Surface Area of Sol-Gel Derived Nano-Hydroxyapatite Powder

    NASA Astrophysics Data System (ADS)

    Kapoor, Seema; Batra, Uma; Kohli, Suchita

    2011-12-01

    Hydroxyapatite (HAP) ceramics have been recognized as substitute materials for bone and teeth in orthopedic and dentistry field due to their chemical and biological similarity to human hard tissue. The nanosized and nanocrystalline forms of HAP have great potential to revolutionize the hard tissue-engineering field, starting from bone repair and augmentation to controlled drug delivery systems. This paper reports the synthesis of biomimetic nano-hydroxyapatite (HAP) by sol-gel method using calcium nitrate tetrahydrate (CNT) and potassium dihydrogen phosphate (KDP) as calcium and phosphorus precursors, respectively to obtain a desired Ca/P ratio of 1.67. Deionized water was used as a diluting media for HAP sol preparation and ammonia was used to adjust the pH to 11. After aging, the HAP gel was dried at 55 °C and sintered to different temperatures (200 °C, 400 °C, 600 °C, 800 °C, 1000 °C and 1200 °C). The dried and sintered powders were characterized for phase composition using Fourier transform infrared (FTIR) spectroscopy and X-ray diffraction (XRD). The particle size and morphology was studied using transmission electron microscopy (TEM). The thermal behavior of the dried HAP nanopowder was studied in the temperature range of 55 °C to 1000 °C using thermal gravimetric analyser (TGA). The BET surface area of absorbance was determined by Nitrogen adsorption using Brunauer-Emmett-Teller (BET) method. The presence of characteristic peaks of the phosphate and OH groups in FTIR spectrums confirmed the formation of pure HAP in dried as well as sintered powders. XRD results also confirmed the formation of stoichiometric nano-HAP. Sintering revealed that with increase in temperature, both the crystallinity and crystallite size of nano-HAP particles increased. The synthesized nano-HAP powder was found to be stable upto 1000 °C without any additional phase other than HAP, whereas peak of β-TCP (tricalcium phosphate) was observed at 1200 °C. Photomicrograph of

  8. Sintering Effects on Morphology, Thermal Stability and Surface Area of Sol-Gel Derived Nano-Hydroxyapatite Powder

    SciTech Connect

    Kapoor, Seema; Batra, Uma; Kohli, Suchita

    2011-12-12

    Hydroxyapatite (HAP) ceramics have been recognized as substitute materials for bone and teeth in orthopedic and dentistry field due to their chemical and biological similarity to human hard tissue. The nanosized and nanocrystalline forms of HAP have great potential to revolutionize the hard tissue-engineering field, starting from bone repair and augmentation to controlled drug delivery systems. This paper reports the synthesis of biomimetic nano-hydroxyapatite (HAP) by sol-gel method using calcium nitrate tetrahydrate (CNT) and potassium dihydrogen phosphate (KDP) as calcium and phosphorus precursors, respectively to obtain a desired Ca/P ratio of 1.67. Deionized water was used as a diluting media for HAP sol preparation and ammonia was used to adjust the pH to 11. After aging, the HAP gel was dried at 55 deg. C and sintered to different temperatures (200 deg. C, 400 deg. C, 600 deg. C, 800 deg. C, 1000 deg. C and 1200 deg. C). The dried and sintered powders were characterized for phase composition using Fourier transform infrared (FTIR) spectroscopy and X-ray diffraction (XRD). The particle size and morphology was studied using transmission electron microscopy (TEM). The thermal behavior of the dried HAP nanopowder was studied in the temperature range of 55 deg. C to 1000 deg. C using thermal gravimetric analyser (TGA). The BET surface area of absorbance was determined by Nitrogen adsorption using Brunauer-Emmett-Teller (BET) method. The presence of characteristic peaks of the phosphate and OH groups in FTIR spectrums confirmed the formation of pure HAP in dried as well as sintered powders. XRD results also confirmed the formation of stoichiometric nano-HAP. Sintering revealed that with increase in temperature, both the crystallinity and crystallite size of nano-HAP particles increased. The synthesized nano-HAP powder was found to be stable upto 1000 deg. C without any additional phase other than HAP, whereas peak of {beta}-TCP (tricalcium phosphate) was observed

  9. Braze material for joining ceramic to metal and ceramic to ceramic surfaces and joined ceramic to metal and ceramic to ceramic article

    DOEpatents

    Hunt, T.K.; Novak, R.F.

    1991-05-07

    An improved active metal braze filler material is provided in which the coefficient of thermal expansion of the braze filler is more closely matched with that of the ceramic and metal, or two ceramics, to provide ceramic to metal, or ceramic to ceramic, sealed joints and articles which can withstand both high temperatures and repeated thermal cycling without failing. The braze filler material comprises a mixture of a material, preferably in the form of a powder, selected from the group consisting of molybdenum, tungsten, silicon carbide and mixtures thereof, and an active metal filler material selected from the group consisting of alloys or mixtures of nickel and titanium, alloys or mixtures of nickel and zirconium, alloys or mixtures of nickel, titanium, and copper, alloys or mixtures of nickel, titanium, and zirconium, alloys or mixtures of niobium and nickel, alloys or mixtures of niobium and zirconium, alloys or mixtures of niobium and titanium, alloys or mixtures of niobium, titanium, and nickel, alloys or mixtures of niobium, zirconium, and nickel, and alloys or mixtures of niobium, titanium, zirconium, and nickel. The powder component is selected such that its coefficient of thermal expansion will effect the overall coefficient of thermal expansion of the braze material so that it more closely matches the coefficients of thermal expansion of the ceramic and metal parts to be joined. 3 figures.

  10. Braze material for joining ceramic to metal and ceramic to ceramic surfaces and joined ceramic to metal and ceramic to ceramic article

    DOEpatents

    Hunt, Thomas K.; Novak, Robert F.

    1991-01-01

    An improved active metal braze filler material is provided in which the coefficient of thermal expansion of the braze filler is more closely matched with that of the ceramic and metal, or two ceramics, to provide ceramic to metal, or ceramic to ceramic, sealed joints and articles which can withstand both high temperatures and repeated thermal cycling without failing. The braze filler material comprises a mixture of a material, preferably in the form of a powder, selected from the group consisting of molybdenum, tungsten, silicon carbide and mixtures thereof, and an active metal filler material selected from the group consisting of alloys or mixtures of nickel and titanium, alloys or mixtures of nickel and zirconium, alloys or mixtures of nickel, titanium, and copper, alloys or mixtures of nickel, titanium, and zirconium, alloys or mixtures of niobium and nickel, alloys or mixtures of niobium and zirconium, alloys or mixtures of niobium and titanium, alloys or mixtures of niobium, titanium, and nickel, alloys or mixtures of niobium, zirconium, and nickel, and alloys or mixtures of niobium, titanium, zirconium, and nickel. The powder component is selected such that its coefficient of thermal expansion will effect the overall coefficient of thermal expansion of the braze material so that it more closely matches the coefficients of thermal expansion of the ceramic and metal parts to be joined.

  11. Osteogenesis with hematopoiesis simulating infection in a hydroxyapatite orbital implant.

    PubMed

    Jordan, David R; Belliveau, Michel J; Brownstein, Seymour; Padmore, Ruth F

    2009-01-01

    A 28-year-old woman underwent secondary orbital implant surgery with placement of a hydroxyapatite implant. Over the next 7 years she underwent 3 drilling procedures. She began having copious discharge 1 year after the last drilling procedure. She was seen on numerous occasions with socket discharge, unresponsive to a variety of topical and oral antibiotics. Clinically, with the conjunctiva diffusely inflamed, the implant tender to touch, and the presence of a pyogenic granuloma, implant infection was suspected and the implant subsequently removed. Histopathologic assessment revealed widespread lamellar bone formation, including focal areas of marrow with active extramedullary hematopoiesis. There was no evidence of an inflammatory process or infection. Postoperatively the patient's symptoms and signs resolved. Extramedullary hematopoiesis within hydroxyapatite implants is rare. Porous orbital implant infection is also rare. Osteogenesis with extramedullary hematopoiesis simulating implant infection has not previously been reported. PMID:19273939

  12. Nanocrystalline hydroxyapatite prepared under various pH conditions

    NASA Astrophysics Data System (ADS)

    Palanivelu, R.; Mary Saral, A.; Ruban Kumar, A.

    2014-10-01

    Hydroxyapatite (HAP) has sovereign biomedical application due to its excellent biocompatibility, chemical and crystallographic similitude with natural human bone. In this present work, we discussed about the role of pH in the synthesis of calcium phosphate compound using calcium nitrate tetrahydrate and di-ammonium hydrogen phosphate as starting materials by chemical precipitation method assisted with ultrasonic irradiation technique. 5% polyethylene glycol (PEG600) is added along with the precursors under various pH condition of 7, 9 and 11 respectively. The functional group analysis, crystallized size and fraction of crystallized size are confirmed using Fourier Transformation Infra-Red spectroscopy and X-ray diffraction pattern. Morphological observations are done by scanning electron microscope. The results revealed the presence of nanocrystalline hydroxyapatite at pH above 9.

  13. Dissolution rates of carbonated hydroxyapatite in hydrochloric acid.

    PubMed

    Hankermeyer, Christine R; Ohashi, Kevin L; Delaney, David C; Ross, John; Constantz, Brent R

    2002-02-01

    Osteoclasts have been shown to dissolve efficiently and effectively the mineral phase of bone by locally controlling the environment surrounding the cell. Although this mineral phase has been identified and well characterized as carbonated hydroxyapatite, there is little understanding of the factors that affect the dissolution properties of this mineral phase. Mimicking the mechanism by which osteoclasts dissolve the mineral phase of bone may provide insight into methods for the decalcification of atherosclerotic mineral deposits in the vascular system. Accordingly, a detailed characterization of the effects of various chemical and mechanical parameters on the dissolution of carbonated hydroxyapatite mineral was investigated in this study. Increases in the mineral dissolution rate (2-10 times) were associated with increases in dissolving solution [H+], osmolality, temperature, and flow rate. Mineral dissolution rate increases (5-8 times) were associated with greater surface area of the mineral and mechanical agitation of the dissolving solution. PMID:11771694

  14. Antimicrobial and cytotoxicity evaluation of aliovalent substituted hydroxyapatite

    NASA Astrophysics Data System (ADS)

    Shanmugam, Sumathi; Gopal, Buvaneswari

    2014-06-01

    Aliovalent ion substituted hydroxyapatite of formulae BiNaCa3(PO4)3OH, Bi0.5M0.5Ca4(PO4)3OH (M = K, Ag) were synthesized and characterized. Antimicrobial properties of these synthesized materials were studied quantitatively by spread plate method against the microorganisms Escherichia coli (gram negative bacteria), Staphylococcus aureus (gram positive bacteria) and Candida albicans (yeast). Among the substituted hydroxyapatite compounds bismuth and silver substituted compound of formula Bi0.5Ag0.5Ca4(PO4)3OH shown excellent activity against all the three organisms. Cytotoxicity study was carried out against mouse fibroblast NIH-3T3 cell line in two different concentrations 10 μg/mL and 20 μg/mL by MTT assay method.

  15. Electrohydrodynamic coating of metal with nano-sized hydroxyapatite.

    PubMed

    Li, Xiang; Huang, Jie; Ahmad, Zeeshan; Edirisinghe, Mohan

    2007-01-01

    Electrohydrodynamic spray deposition of a hydroxyapatite (HA) suspension consisting of nano-particles has been used to create a hydroxyapatite coating comprising of nanostructured surface topography. Preliminary coating experiments were carried out on an Al substrate and 30 s was found to be the most appropriate coating time. HA coating on titanium for this duration was found to be well-bonded to the substrate after heat-treatment. A thickness of 2 mum was achieved in 30 s and formation of a bone-like apatite on the surface was detected after incubation of the heat-treated coated Ti in simulated body fluid. Therefore, we have uncovered a new procedure by which nano-biomaterials can be deposited on real orthopedic substrates to prepare bioactive thin coatings in a simple and easy manner. PMID:18032815

  16. Hydroxyapatite: Vibrational spectra and monoclinic to hexagonal phase transition

    NASA Astrophysics Data System (ADS)

    Slepko, Alexander; Demkov, Alexander A.

    2015-02-01

    Fundamental studies of biomaterials are necessary to deepen our understanding of their degradation and to develop cure for related illnesses. Biomineral hydroxyapatite Ca10(PO4)6(OH)2 is the main mineral constituent of mammal bone, and its synthetic analogues are used in biomedical applications. The mineral can be found in either hexagonal or monoclinic form. The transformation between these two phases is poorly understood, but knowing its mechanism may be critical to reversing processes in bone related to aging. Using density functional theory, we investigate the mechanisms of the phase transformation and estimate the transition temperature to be 680 K in fair agreement with the experimental temperature of 470 K. We also report the heat capacity of hydroxyapatite and a peculiarity in its phonon dispersion that might allow for non-destructive measurements of the crystal composition with applications in preventive medical screening for bone mineral loss.

  17. Improving the degradation behavior and in vitro biological property of nano-hydroxyapatite surface- grafted with the assist of citric acid.

    PubMed

    Jiang, Liuyun; Jiang, Lixin; Xiong, Chengdong; Su, Shengpei

    2016-10-01

    To obtain ideal nano-hydroxyapatite(n-HA) filler for poly(lactide-co-glycolide) (PLGA), a new surface-grafting with the assist of citric acid for nano-hydroxyapatite (n-HA) was designed, and the effect of n-HA surface-grafted with or without citric acid on in vitro degradation behavior and cells viability was studied by the experiments of soaking in simulated body fluid (SBF) and incubating with human osteoblast-like cells (MG-63). The change of pH value, tensile strength reduction, the surface deposits, cells attachment and proliferation of samples during the soaking and incubation were investigated by means of pH meter, electromechanical universal tester, scanning electron microscope (SEM) coupled with energy-dispersive spectro-scopy (EDS), fluorescence microscope and MTT method. The results showed that the introduction of citric acid not only delayed the strength reduction during the degradation by inhibiting the detachment of n-HA from PLGA, but also endowed it better cell attachment and proliferation, suggesting that the n-HA surface-grafted with the assist of citric acid was an important bioactive ceramic fillers for PLGA used as bone materials. PMID:27343845

  18. A preclinical study of stem subsidence and graft incorporation after femoral impaction grafting using porous hydroxyapatite as a bone graft extender.

    PubMed

    Howie, Donald W; McGee, Margaret A; Callary, Stuart A; Carbone, Angelo; Stamenkov, Roumen B; Bruce, Warrick J; Findlay, David M

    2011-10-01

    This preclinical in vivo screening study compared bone graft incorporation and stem subsidence in cemented hemiarthroplasty after femoral impaction bone grafting with either morselized allograft bone (n = 5, control group) or a 1:1 mix of allograft and porous hydroxyapatite ceramics (HA) granules (n = 5, HA group). At 14 weeks, there was excellent bone graft incorporation by bone, and the stems were well fixed in both groups. The median subsidence at the cement-bone interface, measured using radiostereometric analysis, was 0.14 and 0.93 mm in the control and HA groups, respectively. The comparable histologic results between groups and good stem fixation in this study support the conduct of a larger scale investigation of the use of porous HA in femoral impaction bone grafting at revision hip arthroplasty. PMID:21802252

  19. Pulsed laser deposition of hydroxyapatite thin films on Ti-5Al-2.5Fe substrates with and without buffer layers

    NASA Astrophysics Data System (ADS)

    Nelea, V.; Ristoscu, C.; Chiritescu, C.; Ghica, C.; Mihailescu, I. N.; Pelletier, H.; Mille, P.; Cornet, A.

    2000-12-01

    We present a method for processing hydroxyapatite (HA) thin films on Ti-5Al-2.5Fe substrates. The films were grown by pulsed laser deposition (PLD) in vacuum at room temperature, using a KrF∗ excimer laser. The amorphous as-deposited HA films were recrystallized in ambient air by a thermal treatment at 550°C. The best results have been obtained when inserting a buffer layer of ceramic materials (TiN, ZrO2 or Al2O3). The films were characterized by complementary techniques: grazing incidence X-ray diffraction (GIXRD), scanning electron microscopy (SEM), cross-section transmission electron microscopy (XTEM), SAED, energy dispersive X-ray spectroscopy (EDS) and nanoindentation. The samples with buffer interlayer preserve the stoichiometry are completely recrystallized and present better mechanical characteristics as compared with that without buffer interlayer.

  20. Growth of one-dimensional single-crystalline hydroxyapatite nanorods

    NASA Astrophysics Data System (ADS)

    Ren, Fuzeng; Ding, Yonghui; Ge, Xiang; Lu, Xiong; Wang, Kefeng; Leng, Yang

    2012-06-01

    A facile, effective and template/surfactant-free hydrothermal route in the presence of sodium bicarbonate was developed to synthesize highly uniform single-crystalline hydroxyapatite (HA) nanorods with the lengths of several hundred nanometers and aspect ratio up to ˜20. One dimensional (1-D) growth and aspect ratio could be controlled by hydrothermal reaction time and temperature. The longitudinal axis, also the growth direction of the nanorods, is parallel to the [001] direction of HA hexagonal crystal structure.

  1. Advanced Microstructural Study of Suspension Plasma Sprayed Hydroxyapatite Coatings

    NASA Astrophysics Data System (ADS)

    Podlesak, Harry; Pawlowski, Lech; D'Haese, Romain; Laureyns, Jacky; Lampke, Thomas; Bellayer, Severine

    2010-03-01

    Fine, home-synthesized, hydroxyapatite powder was formulated with water and alcohol to obtain a suspension used to plasma spray coatings onto a titanium substrate. The deposition process was optimized using statistical design of 2 n experiments with two variables: spray distance and electric power input to plasma. X-ray diffraction (XRD) was used to determine quantitatively the phase composition of obtained deposits. Raman microscopy and electron probe microanalysis (EPMA) enabled localization of the phases in different positions of the coating cross sections. Transmission electron microscopic (TEM) study associated with energy-dispersive x-ray spectroscopy (EDS) enabled visualization and analysis of a two-zone microstructure. One zone contained crystals of hydroxyapatite, tetracalcium phosphate, and a phase rich in calcium oxide. This zone included lamellas, usually observed in thermally sprayed coatings. The other zone contained fine hydroxyapatite grains that correspond to nanometric and submicrometric solids from the suspension that were agglomerated and sintered in the cold regions of plasma jet and on the substrate.

  2. XANES Data on Trace Quantities of Iron in Hydroxyapatite Structures

    NASA Astrophysics Data System (ADS)

    Tabor-Morris, A.; Schaefer, B.

    2003-03-01

    Trace elements such as iron are of interest in both biologically and geologically formed apatites. They are thought to occupy substitutional sites at the concentration of about 200 ppm. Most likely metal atoms replace the calcium atom in one of two non-equivalent calcium sites. The inorganic mineral structure hydroxyapatite (which comprises 30% of human and animal bone) consists of Ca_5(OH)(PO_4)3 in a hexagonal crystal structure designated in Herman-Maugin crystallography notation as P63/m or as Number 176 in the International Tables of Crystallography (ITC). Hydroxyapatite formed under geological conditions has the same crystal structure. Hydroxyapatite can also be fabricated synthetically, but has limitations in terms of crystal growth size. The experimental technique of X-ray Absorption Near Edge Structure (XANES) and X-ray Absorption Fine-structure Spectroscopy (XAFS) were used to evaluate the oxidation state of iron. Data was taken at the X-9B line at the National Synchrotron Light Source at Brookhaven National Laboratory.

  3. XANES Data on Metal Ions in Hydroxyapatite Structures

    NASA Astrophysics Data System (ADS)

    Schaefer, Beth; Tabor-Morris, Anne; Simons, Adrian

    2004-03-01

    The experimental technique of X-ray Absorption Near Edge Structure (XANES) was used to compare the absorption edges of different oxidation states of iron, strontium, lead, copper and zinc in the inorganic mineral structure hydroxyapatite and fluoroapatite. Trace elements such as iron, copper, zinc, lead and strontium are of interest in both biologically and geologically formed apatites. They are thought to occupy substitutional sites at the concentration of about 200 ppm. These metal atoms replace the calcium atom in one of two non-equivalent calcium sites. Hydroxyapatite consists of Ca _5 (OH)(PO_4)3 in a hexagonal crystal structure. Hydroxyapatite formed under geological conditions has the same crystal structure. Data was taken at the X-9B line at the National Synchrotron Light Source at Brookhaven National Laboratory. Samples were obtained from Dr. Susan G. Sheridan, at the University of Notre Dame, Dr. Catherine Skinner from Yale University, Dr. John Rakovan at Miami University in Ohio, Dr. Richard Riman at Rutgers University.

  4. Calcium Deficient Hydroxyapatite for Medical Application Prepared by Hydrothermal Method

    NASA Astrophysics Data System (ADS)

    Ioku, Koji; Kamitakahara, Masanobu; Ikeda, Tohru

    2010-11-01

    Hydrothermal processing plays a key role in the synthesis of biomaterials with excellent biocompatibility in the physiological environment. Especially, calcium phosphates are paid to much attention for the regenerative medicine. Two kinds of porous materials of hydroxyapatite with 70% porosity were prepared. One of them is a newly developed calcium-deficient hydroxyapatite composed of rod-shaped particles of about 20 μm in length synthesized hydrothermally (HHA) and the other one is the stoichiometric hydroxyapatite (SHA) prepared by the conventional sintering method. These materials were used for animal implantation tests to compare these biological responses. In the rabbit femur, implanted HHA was slowly resorbed and then most of the implanted HHA was resorbed after 72 weeks. The implanted SHA was unresorbed throughout the experimental period. The volume of newly formed bone and the number of osteoclasts in the implanted region were significantly larger in HHA than in SHA after 24 weeks. Results in the present research suggested that the activity of osteoclasts correlated to the bone forming activity of osteoblasts. The method to synthesize biodegradable pure calcium-deficient HA is expected to provide adequate biodegradability and bone replaceability.

  5. Multifunctional hydroxyapatite nanofibers and microbelts as drug carriers.

    PubMed

    Hou, Zhiyao; Yang, Piaoping; Lian, Hongzhou; Wang, Lili; Zhang, Cuimiao; Li, Chunxia; Chai, Ruitao; Cheng, Ziyong; Lin, Jun

    2009-07-13

    Luminescent, mesoporous, and bioactive europium-doped hydroxyapatite (HAp:Eu(3+)) nanofibers and microbelts have been prepared by a combination of sol-gel and electrospinning processes with a cationic surfactant as template. The obtained multifunctional hydroxyapatite nanofibers and microbelts, which have mesoporous structure and red luminescence, were tested as drug carriers by investigating their drug-storage/release properties with ibuprofen (IBU) as model drug. X-ray diffraction, scanning electron microscopy (SEM), transmission electron microscopy (TEM), high-resolution (HR) TEM, FTIR spectroscopy, N(2) adsorption/desorption, photoluminescence (PL) spectra, and UV/Vis spectroscopy were used to characterize the structural, morphological, textural, and optical properties of the resulting samples. The results reveal that the multifunctional hydroxyapatites exhibit irregular mesostructure, and have fiberlike and beltlike morphologies with sizes of several hundred nanometers in width and several millimeters in length. The IBU-loaded HAp:Eu(3+) system shows red luminescence of Eu(3+) ((5)D(0)-(7)F(0,1,2)) under UV irradiation and controlled release of IBU. In addition, the emission intensity of Eu(3+) in the drug carrier system varies with the released amount of IBU, and thus drug release can be easily tracked and monitored by the change in luminescence intensity. PMID:19496099

  6. Controlled synthesis and thermal stability of hydroxyapatite hierarchical microstructures

    SciTech Connect

    Sun, Ruixue; Chen, Kezheng; Liao, Zhongmiao; Meng, Nan

    2013-03-15

    Highlights: ► Hydroxyapatite hierarchical microstructures have been synthesized by a facile method. ► The morphology and size of the building units of 3D structures can be controlled. ► The hydroxyapatite with 3D structure is morphologically and structurally stable up to 800 °C. - Abstract: Hydroxyapatite (HAp) hierarchical microstructures with novel 3D morphology were prepared through a template- and surfactant-free hydrothermal homogeneous precipitation method. Field emission scanning electron microscopy (FESEM), high-resolution transmission electron microscopy (HRTEM), and X-ray diffraction (XRD) were used to characterize the morphology and composition of the synthesized products. Interestingly, the obtained HAp with 3D structure is composed of one-dimensional (1D) nanorods or two-dimensional (2D) nanoribbons, and the length and morphology of these building blocks can be controlled through controlling the pH of the reaction. The building blocks are single crystalline and have different preferential orientation growth under different pH conditions. At low pH values, octacalcium phosphate (OCP) phase formed first and then transformed into HAp phase due to the increased pH value caused by the decomposition of urea. The investigation on the thermal stability reveals that the prepared HAp hierarchical microstructures are morphologically and structurally stable up to 800 °C.

  7. Synthesis of fluorapatite–hydroxyapatite nanoparticles and toxicity investigations

    PubMed Central

    Montazeri, N; Jahandideh, R; Biazar, Esmaeil

    2011-01-01

    In this study, calcium phosphate nanoparticles with two phases, fluorapatite (FA; Ca10(PO4)6F2) and hydroxyapatite (HA; Ca10(PO4)6(OH)2), were prepared using the solgel method. Ethyl phosphate, hydrated calcium nitrate, and ammonium fluoride were used, respectively, as P, Ca, and F precursors with a Ca:P ratio of 1:72. Powders obtained from the sol-gel process were studied after they were dried at 80°C and heat treated at 550°C. The degree of crystallinity, particle and crystallite size, powder morphology, chemical structure, and phase analysis were investigated by scanning electron microscopy (SEM), X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), and Zetasizer experiments. The results of XRD analysis and FTIR showed the presence of hydroxyapatite and fluorapatite phases. The sizes of the crystallites estimated from XRD patterns using the Scherrer equation and the crystallinity of the hydroxyapatite phase were about 20 nm and 70%, respectively. Transmission electron microscope and SEM images and Zetasizer experiments showed an average size of 100 nm. The in vitro behavior of powder was investigated with mouse fibroblast cells. The results of these experiments indicated that the powders were biocompatibile and would not cause toxic reactions. These compounds could be applied for hard-tissue engineering. PMID:21499417

  8. Synthesis of fluorapatite-hydroxyapatite nanoparticles and toxicity investigations.

    PubMed

    Montazeri, N; Jahandideh, R; Biazar, Esmaeil

    2011-01-01

    In this study, calcium phosphate nanoparticles with two phases, fluorapatite (FA; Ca(10)(PO(4))(6)F(2)) and hydroxyapatite (HA; Ca(10)(PO(4))(6)(OH)(2)), were prepared using the solgel method. Ethyl phosphate, hydrated calcium nitrate, and ammonium fluoride were used, respectively, as P, Ca, and F precursors with a Ca:P ratio of 1:72. Powders obtained from the sol-gel process were studied after they were dried at 80°C and heat treated at 550°C. The degree of crystallinity, particle and crystallite size, powder morphology, chemical structure, and phase analysis were investigated by scanning electron microscopy (SEM), X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), and Zetasizer experiments. The results of XRD analysis and FTIR showed the presence of hydroxyapatite and fluorapatite phases. The sizes of the crystallites estimated from XRD patterns using the Scherrer equation and the crystallinity of the hydroxyapatite phase were about 20 nm and 70%, respectively. Transmission electron microscope and SEM images and Zetasizer experiments showed an average size of 100 nm. The in vitro behavior of powder was investigated with mouse fibroblast cells. The results of these experiments indicated that the powders were biocompatible and would not cause toxic reactions. These compounds could be applied for hard-tissue engineering. PMID:21499417

  9. Modification of the structure and composition of Ca10(PO4)6(OH)2 ceramic coatings by changing the deposition conditions in O2 and Ar

    NASA Astrophysics Data System (ADS)

    Donkov, N.; Zykova, A.; Safonov, V.; Kolesnikov, D.; Goncharov, I.; Yakovin, S.; Georgieva, V.

    2014-05-01

    Hydroxyapatite Ca10(PO4)6(OH)2 (HAp) is a material considered to be used to form structural matrices in the mineral phase of bone, dentin and enamel. HAp ceramic materials and coatings are widely applied in medicine and dentistry because of their ability to increase the tissue response to the implant surface and promote bone ingrowth and osseoconduction processes. The deposition conditions affect considerably the structure and bio-functionality of the HAp coatings. We focused our research on developing deposition methods allowing a precise control of the structure and stoichiometric composition of HAp thin films. We found that the use of O2 as a reactive gas improves the quality of the sputtered hydroxyapatite coatings by resulting in the formation of films of better stoichiometry with a fine crystalline structure.

  10. Current Classification of Ceramic Materials

    NASA Astrophysics Data System (ADS)

    Reh, Hubertus

    Materials are grouped into three large families (Fig 3.2). Ceramic materials are part of the group of non-metallic and inorganic materials, which also includes glass, natural stone and inorganic binders (cement, lime, gypsum). But what defines ceramic materials? In Continental Europe the following definition has been agreed.

  11. Lightweight high performance ceramic material

    DOEpatents

    Nunn, Stephen D [Knoxville, TN

    2008-09-02

    A sintered ceramic composition includes at least 50 wt. % boron carbide and at least 0.01 wt. % of at least one element selected from the group consisting of Y, La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy Ho, Er, Tm, Yb, and Lu, the sintered ceramic composition being characterized by a density of at least 90% of theoretical density.

  12. Improved Tensile Test for Ceramics

    NASA Technical Reports Server (NTRS)

    Osiecki, R. A.

    1982-01-01

    For almost-nondestructive tensile testing of ceramics, steel rod is bonded to sample of ceramic. Assembly is then pulled apart in conventional tensile-test machine. Test destroys only shallow surface layer which can be machined away making specimen ready for other uses. Method should be useful as manufacturing inspection procedure for low-strength brittle materials.

  13. Method of forming ceramic bricks

    DOEpatents

    Poeppel, Roger B.; Claar, Terry D.; Silkowski, Peter

    1988-01-01

    A method for forming free standing ceramic bricks for use as tritium breeder material is disclosed. Aqueous solutions of sodium carbonate and potassium carbonate are mixed with an organic hydrocolloid dispersion and powdered lithium carbonate, spray dried, and ceramic bricks formed by molding in a die and firing.

  14. Method of forming ceramic bricks

    DOEpatents

    Poeppel, Roger B.; Claar, Terry D.; Silkowski, Peter

    1988-09-06

    A method for forming free standing ceramic bricks for use as tritium breeder material is disclosed. Aqueous solutions of sodium carbonate and potassium carbonate are mixed with an organic hydrocolloid dispersion and powdered lithium carbonate, spray dried, and ceramic bricks formed by molding in a die and firing.

  15. Ceramic applications in turbine engines

    NASA Technical Reports Server (NTRS)

    Byrd, J. A.; Janovicz, M. A.; Thrasher, S. R.

    1981-01-01

    Development testing activities on the 1900 F-configuration ceramic parts were completed, 2070 F-configuration ceramic component rig and engine testing was initiated, and the conceptual design for the 2265 F-configuration engine was identified. Fabrication of the 2070 F-configuration ceramic parts continued, along with burner rig development testing of the 2070 F-configuration metal combustor in preparation for 1132 C (2070 F) qualification test conditions. Shakedown testing of the hot engine simulator (HES) rig was also completed in preparation for testing of a spin rig-qualified ceramic-bladed rotor assembly at 1132 C (2070 F) test conditions. Concurrently, ceramics from new sources and alternate materials continued to be evaluated, and fabrication of 2070 F-configuration ceramic component from these new sources continued. Cold spin testing of the critical 2070 F-configuration blade continued in the spin test rig to qualify a set of ceramic blades at 117% engine speed for the gasifier turbine rotor. Rig testing of the ceramic-bladed gasifier turbine rotor assembly at 108% engine speed was also performed, which resulted in the failure of one blade. The new three-piece hot seal with the nickel oxide/calcium fluoride wearface composition was qualified in the regenerator rig and introduced to engine operation wiwth marginal success.

  16. Method of forming ceramic bricks

    DOEpatents

    Poeppel, R.B.; Claar, T.D.; Silkowski, P.

    1987-04-22

    A method for forming free standing ceramic bricks for use as tritium breeder material is disclosed. Aqueous solutions of sodium carbonate and potassium carbonate are mixed with an organic hydrocolloid dispersion and powdered lithium carbonate, spray dried, and ceramic bricks formed by molding in a die and firing.

  17. Ceramic applications in turbine engines

    NASA Technical Reports Server (NTRS)

    Helms, H. E.; Heitman, P. W.; Lindgren, L. C.; Thrasher, S. R.

    1984-01-01

    The application of ceramic components to demonstrate improved cycle efficiency by raising the operating temperature of the existing Allison IGI 404 vehicular gas turbine engine is discussed. This effort was called the Ceramic Applications in Turbine Engines (CATE) program and has successfully demonstrated ceramic components. Among these components are two design configurations featuring stationary and rotating caramic components in the IGT 404 engine. A complete discussion of all phases of the program, design, materials development, fabrication of ceramic components, and testing-including rig, engine, and vehicle demonstation test are presented. During the CATE program, a ceramic technology base was established that is now being applied to automotive and other gas turbine engine programs. This technology base is outlined and also provides a description of the CATE program accomplishments.

  18. Protective coating for ceramic materials

    NASA Technical Reports Server (NTRS)

    Kourtides, Demetrius A. (Inventor); Churchward, Rex A. (Inventor); Lowe, David M. (Inventor)

    1994-01-01

    A protective coating for ceramic materials such as those made of silicon carbide, aluminum oxide, zirconium oxide, aluminoborosilicate and silicon dioxide, and a thermal control structure comprising a ceramic material having coated thereon the protective coating. The protective coating contains, in admixture, silicon dioxide powder, colloidal silicon dioxide, water, and one or more emittance agents selected from silicon tetraboride, silicon hexaboride, silicon carbide, molybdenum disilicide, tungsten disilicide and zirconium diboride. In another aspect, the protective coating is coated on a flexible ceramic fabric which is the outer cover of a composite insulation. In yet another aspect, a metallic foil is bonded to the outer surface of a ceramic fabric outer cover of a composite insulation via the protective coating. A primary application of this invention is as a protective coating for ceramic materials used in a heat shield for space vehicles subjected to very high aero-convective heating environments.

  19. Ceramic membrane development in NGK

    NASA Astrophysics Data System (ADS)

    Araki, Kiyoshi; Sakai, Hitoshi

    2011-05-01

    NGK Insulators, Ltd. was established in 1919 to manufacture the electric porcelain insulators for power transmission lines. Since then, our business has grown as one of the world-leading ceramics manufacturing companies and currently supply with the various environmentally-benign ceramic products to worldwide. In this paper, ceramic membrane development in NGK is described in detail. We have been selling ceramic microfiltration (MF) membranes and ultra-filtration (UF) membranes for many years to be used for solid/liquid separation in various fields such as pharmaceutical, chemical, food and semiconductor industries. In Corporate R&D, new ceramic membranes with sub-nanometer sized pores, which are fabricated on top of the membrane filters as support, are under development for gas and liquid/liquid separation processes.

  20. Bone Regeneration Using Hydroxyapatite Sponge Scaffolds with In Vivo Deposited Extracellular Matrix.

    PubMed

    Ventura, Reiza Dolendo; Padalhin, Andrew Reyes; Min, Young-Ki; Lee, Byong-Taek

    2015-11-01

    There is currently an increased interest in studying the extracellular matrix (ECM) and its potential applications for tissue engineering and regenerative medicine. The ECM plays an important role by providing adhesive substrates to cells during migration, morphogenesis, differentiation, and homeostasis by signaling biochemical and biomechanical cues to cells. In this study, the ECM was incorporated into hydroxyapatite by implanting sponge replica scaffolds in subcutaneous pockets in rats, and the implants were tested for bone regeneration potential. The resulting scaffolds were characterized using scanning electron microscopy, confocal microscopy, DNA and RNA quantification, tissue staining, energy dispersive X-ray spectroscopy analysis, compressive strength testing, porosity, and pore size distribution analysis using bare scaffolds as a control reference. Biocompatibility was assessed using MC3T3-E1 preosteoblast cells and in vivo studies were carried out by implanting decellularized scaffolds in 11 mm radial defects in New Zealand rabbits for 4 and 8 weeks to determine the effect of the in vivo deposited ECM. Material characterization indicated that a 2-week decellularized scaffold was the best among the samples, with an evenly distributed ECM visible on hematoxylin and eosin-stained tissue sections, a compressive strength of 2.53 ± 0.68 MPa, a porosity of 58.08 ± 3.32% and a pore size distribution range of 10-150 μm. In vivo results showed no severe inflammation, with increased cell infiltration followed by dense matrix deposition after 4 weeks and new bone formation at 8 weeks. The results indicate that incorporation of an in vivo deposited ECM into ceramic scaffolds can potentially improve bone regeneration. PMID:26228909

  1. Treatment of a Simple Bone Cyst Using a Cannulated Hydroxyapatite Pin.

    PubMed

    Shirai, Toshiharu; Tsuchiya, Hiroyuki; Terauchi, Ryu; Tsuchida, Shinji; Mizoshiri, Naoki; Ikoma, Kazuya; Fujiwara, Hiroyoshi; Miwa, Shinji; Kimura, Hiroaki; Takeuchi, Akihiko; Hayashi, Katsuhiro; Yamamoto, Norio; Kubo, Toshikazu

    2015-06-01

    Simple bone cysts (SBCs) are benign bone tumors. However, the treatment of SBCs remains controversial because of their healing rate and the invasiveness of surgery. The purpose of the present study was to evaluate the treatment of SBCs using a cannulated hydroxyapatite (HA) pin.A total of 43 patients (35 males, 8 females; mean age 12.1 years; age range, 5-22 years) with SBCs were treated with continuous decompression by inserting ceramic HA pins between 1989 and 2014. The SBCs were located in the calcaneus in 23, the humerus in 15, the femur in 3, and the pelvis in 2 cases. In all patients, minimal fenestration of the cyst wall and curettage and multiple drilling in the cyst wall were performed, followed by insertion of the HA pin. The mean follow-up period was 26.6 months. Operating time, healing period, risk factors for recurrence, and the cure rate were evaluated.Healing was achieved without intervention in 38 patients after a mean of 6.4 months. Two patients had persistent small residual cysts, which had no changes after 1 year at the latest follow-up. There were 5 patients with recurrences (humerus 4, femur 1), who were cured by curettage and artificial bone grafting. The final healing rate by cannulation only using an HA pin was 88.2%. On Fisher exact test, age, site of SBCs, and distance from the physis were found to be significantly associated with SBC recurrence (P < 0.05).In the present study, cannulation using an HA pin for SBCs was found to be a useful technique, particularly for calcaneal cysts, because it is a minimally invasive procedure with a high cure rate. In patients <10 years, involvement of the humerus and contact with the growth plate were significant risk factors for SBC recurrence. PMID:26107670

  2. Treatment of a Simple Bone Cyst Using a Cannulated Hydroxyapatite Pin

    PubMed Central

    Shirai, Toshiharu; Tsuchiya, Hiroyuki; Terauchi, Ryu; Tsuchida, Shinji; Mizoshiri, Naoki; Ikoma, Kazuya; Fujiwara, Hiroyoshi; Miwa, Shinji; Kimura, Hiroaki; Takeuchi, Akihiko; Hayashi, Katsuhiro; Yamamoto, Norio; Kubo, Toshikazu

    2015-01-01

    Abstract Simple bone cysts (SBCs) are benign bone tumors. However, the treatment of SBCs remains controversial because of their healing rate and the invasiveness of surgery. The purpose of the present study was to evaluate the treatment of SBCs using a cannulated hydroxyapatite (HA) pin. A total of 43 patients (35 males, 8 females; mean age 12.1 years; age range, 5–22 years) with SBCs were treated with continuous decompression by inserting ceramic HA pins between 1989 and 2014. The SBCs were located in the calcaneus in 23, the humerus in 15, the femur in 3, and the pelvis in 2 cases. In all patients, minimal fenestration of the cyst wall and curettage and multiple drilling in the cyst wall were performed, followed by insertion of the HA pin. The mean follow-up period was 26.6 months. Operating time, healing period, risk factors for recurrence, and the cure rate were evaluated. Healing was achieved without intervention in 38 patients after a mean of 6.4 months. Two patients had persistent small residual cysts, which had no changes after 1 year at the latest follow-up. There were 5 patients with recurrences (humerus 4, femur 1), who were cured by curettage and artificial bone grafting. The final healing rate by cannulation only using an HA pin was 88.2%. On Fisher exact test, age, site of SBCs, and distance from the physis were found to be significantly associated with SBC recurrence (P < 0.05). In the present study, cannulation using an HA pin for SBCs was found to be a useful technique, particularly for calcaneal cysts, because it is a minimally invasive procedure with a high cure rate. In patients <10 years, involvement of the humerus and contact with the growth plate were significant risk factors for SBC recurrence. PMID:26107670

  3. Synthesis and structural characterization of nano-hydroxyapatite biomaterials prepared by microwave processing

    NASA Astrophysics Data System (ADS)

    Ramli, Rosmamuhamadani; Arawi, Ainaa Zafirah Omar; Talari, Mahesh Kumar; Mahat, Mohd Muzamir; Jais, Umi Sarah

    2012-07-01

    Synthetic hydroxyapatite, (HA, Ca10(PO4)6(OH)2), is an attractive and widely utilized bio-ceramic material for orthopedic and dental implants because of its close resemblance of native tooth and bone crystal structure. Synthetic HA exhibits excellent osteoconductive properties. Osteoconductivity means the ability to provide the appropriate scaffold or template for bone formation. Calcium phosphate biomaterials [(HA), tri-calcium phosphate (TCP) and biphasic calcium phosphate (HA/TCP)] with appropriate three-dimensional geometry are able to bind and concentrate endogenous bone morphogenetic proteins in circulation, and may become osteoinductive and can be effective carriers of bone cell seeds. This HA can be used in bio-implants as well as drug delivery application due to the unique properties of HA. Biomaterials synthesized from the natural species like mussel shells have additional benefits such as high purity, less expensive and high bio compatibility. In this project, HA-nanoparticles of different crystallite size were prepared by microwave synthesis of precursors. High purity CaO was extracted from the natural mussel shells for the synthesis of nano HA. Dried nano HA powders were analyzed using X-Ray Diffraction (XRD) technique for the determination of crystal structure and impurity content. Scanning Electron Microscopic (SEM) investigation was employed for the morphological investigation of nano HA powders. From the results obtained, it was concluded that by altering the irradiation time, nano HA powders of different crystallite sizes and morphologies could be produced. Crystallite sizes calculated from the XRD patterns are found to be in the range of 10-55 nm depending on the irradiation time.

  4. Osteogenic cell response to 3-D hydroxyapatite scaffolds developed via replication of natural marine sponges.

    PubMed

    Clarke, S A; Choi, S Y; McKechnie, Melanie; Burke, G; Dunne, N; Walker, G; Cunningham, E; Buchanan, F

    2016-02-01

    Bone tissue engineering may provide an alternative to autograft, however scaffold optimisation is required to maximize bone ingrowth. In designing scaffolds, pore architecture is important and there is evidence that cells prefer a degree of non-uniformity. The aim of this study was to compare scaffolds derived from a natural porous marine sponge (Spongia agaricina) with unique architecture to those derived from a synthetic polyurethane foam. Hydroxyapatite scaffolds of 1 cm(3) were prepared via ceramic infiltration of a marine sponge and a polyurethane (PU) foam. Human foetal osteoblasts (hFOB) were seeded at 1 × 10(5) cells/scaffold for up to 14 days. Cytotoxicity, cell number, morphology and differentiation were investigated. PU-derived scaffolds had 84-91% porosity and 99.99% pore interconnectivity. In comparison marine sponge-derived scaffolds had 56-61% porosity and 99.9% pore interconnectivity. hFOB studies showed that a greater number of cells were found on marine sponge-derived scaffolds at than on the PU scaffold but there was no significant difference in cell differentiation. X-ray diffraction and inductively coupled plasma mass spectrometry showed that Si ions were released from the marine-derived scaffold. In summary, three dimensional porous constructs have been manufactured that support cell attachment, proliferation and differentiation but significantly more cells were seen on marine-derived scaffolds. This could be due both to the chemistry and pore architecture of the scaffolds with an additional biological stimulus from presence of Si ions. Further in vivo tests in orthotopic models are required but this marine-derived scaffold shows promise for applications in bone tissue engineering. PMID:26704539

  5. Processing of nanocrystalline ceramics

    SciTech Connect

    Ciftcioglu, M. . Center for Micro-Engineered Ceramics); Mayo, M.J. )

    1990-01-01

    Methods of preparing non-agglomerated powders for three systems -- yttria, titania, and yttria-stabilized zirconia -- are reviewed. The non-agglomerated nature of these powders should make it possible to sinter them into dense ceramic bodies with nanocrystalline grain sizes. Experiments with yttria-stabilized zirconia have shown that this is indeed the case, with mean linear intercept grain sizes of 60 nm resulting from original powder particle diameters of 13 nm. This ultrafine-grained zirconia is shown, in turn, to have superplastic forming rates 34 times faster than a 0.3 {mu}m-grained commercial zirconia of the same composition. 7 refs., 9 figs.

  6. Ceramic heat pipe wick

    NASA Technical Reports Server (NTRS)

    Seidenberg, Benjamin (Inventor); Swanson, Theodore (Inventor)

    1989-01-01

    A wick for use in a capillary loop pump heat pipe is disclosed. The wick material is an essentially uniformly porous, permeable, open-cell, silicon dioxide/aluminum oxide inorganic ceramic foam having a silica fiber ratio, by weight, of about 78 to 22, respectively, a density of 6 lbs/cu ft, and an average pore size of less than 5 microns. A representative material having these characteristics is Lockheed Missile and Space Company, Inc.'s HTP 6-22. This material is fully compatible with the freons and anhydrous ammonia and allows for the use of these very efficient working fluids, and others, in capillary loops.

  7. Ceramic oxide fibers

    SciTech Connect

    Sowman, H.G.; Johnson, D.D.

    1985-10-01

    Polycrystalline ceramic fibers now available from commercial sources include those of Al/sub 2/O/sub 3/, Al/sub 2/O/sub 3/-SiO/sub 2/O/sub 3/, Al/sub 2/O/sub 3/-B/sub 2/O/sub 3/-SiO/sub 2/, and ZrO/sub 2/-SiO/sub 2/. Continuous filaments in roving, yarn, chopped, bulk, fabric or mat forms can be supplied. Properties and uses of these fibers are discussed. 18 references.

  8. Ceramic component for electrodes

    DOEpatents

    Marchant, David D.; Bates, J. Lambert

    1980-01-01

    A ceramic component suitable for preparing MHD generator electrodes having the compositional formula: Y.sub.x (Mg.sub.y Cr.sub.z).sub.w Al.sub.(1-w) O.sub.3 where x=0.9 to 1.05, y=0.02 to 0.2, z=0.8 to 1.05 and w=1.0 to 0.5. The component is resistant to the formation of hydration products in an MHD environment, has good electrical conductivity and exhibits a lower electrochemical corrosion rate than do comparable compositions of lanthanum chromite.

  9. Effect of silicon, tantalum, and tungsten doping and polarization on bioactivity of hydroxyapatite

    NASA Astrophysics Data System (ADS)

    Dhal, Jharana

    Hydroxyapatite (HAp) ceramics has important applications as bone graft because of the structural and compositional similarities with bone tissue. However, inferior osteogenic capacity to bone and poor mechanical properties have been identified to be major disadvantages of synthetic HAp compared to the living bone tissue. The objective of the current study is to evaluate the effect of doping with higher valent cations (Tungsten, tantalum, and silicon) and polarization or combination of both on change in property of doped HAp and subsequent impact its bioactivity. In vitro study with human osteoblast cells was used to investigate the influences of doping and polarization on bone cell-materials interactions. The bioactivity of doped HAp was compared with pure HAp. Effect of doping and polarization on the change in HAp was investigated by monitoring change in mineral phases, stored charge, and activation energy of HAp. Activation energy of depolarization was used to explain the possible mechanism of polarization in doped samples. Bioactivity of HAp increased when doped with tantalum and tungsten. Polarization further increased the bioactivity of tungsten- and tantalum-doped samples. Increase in bioactivity on polarized and doped samples was attributed to increase in surface energy and increase in surface wettability. Whereas, an increase in bioactivity on doped unpolarized surface was attributed to change in microstructure. Polarized charge calculated from TSDC indicates that polarized charge decreases on tantalum- and tungsten-doped HAp. The decrease in polarized charge was attributed to the presence of significant amount of different phases that may hinder the ionic motion in doped samples. However, for silicon-doped HAp, TSDC study showed no difference in the mechanism of polarization between doped and undoped samples. Increase in silicon doping decreased the grain size though mechanism is not affected by grain size. Total stored charge decreased with increase in

  10. High-temperature corrosion resistance of ceramics and ceramic coatings

    SciTech Connect

    Tortorelli, P.F.

    1996-06-01

    Ceramics and ceramic composites offer the potential to operate fossil energy systems at the higher temperatures necessary for improved energy efficiency and better environmental control. However, because many fossil fuel-derived processes contain sulfur, chlorine, and carbon, as well as oxygen, degradation from high-temperature corrosion and environmental effects arising from reactions of solids with gases and condensable products is a common life-determining factor in operating systems. Ceramic-based products are not immune to such degradation; adequate corrosion resistance must be assured to exploit the technical and economic potential of such materials. This is normally accomplished by using stable, sound oxides that exist in their bulk form, that naturally grow as surface layers upon exposure to an oxidizing environment, or that are deposited as a coating on a susceptible material. It is therefore important to examine the critical issues with respect to more environmental stability of ceramics that have the potential to be corrosion resistant in particular fossil environments. Key aspects include not only chemical compatibility, but the influence of the environment on the mechanical behavior of the ceramic materials. In addition, for coatings, the mechanical reliability of the ceramic is a key issue in that an otherwise corrosion-resistant surface layer must remain sound and adherent in order to provide protection to the underlying substrate. The purpose of this work is to support the development of advanced ceramics and ceramic composites for applications in fossil environments by examining critical issues related to high-temperature corrosion resistance. More specifically, the overall objective of this task is to examine the chemical compatibility and reliability of potentially corrosion-resistant ceramics being developed as protective overcoats and/or structural materials as parts of other work elements funded by the AR&TD Program.

  11. Fast Measurements Of Thermal Diffusivities Of Ceramics

    NASA Technical Reports Server (NTRS)

    Smith, Marnell; Goldstein, Howard E.

    1988-01-01

    Temperature rises of samples compared with reference sample. Apparatus quickly measures thermal diffusivities of ceramics at high temperatures. Produces data on relative thermal diffusivities of as many as six ceramic specimens per hour. Thermal-diffusivity tester makes it easy to determine thermal diffusivities of ceramics. Pronounced effects of processing parameters on thermal properties of ceramics evaluated quickly.

  12. Comparison of the Weibull characteristics of hydroxyapatite and strontium doped hydroxyapatite.

    PubMed

    Yatongchai, Chokchai; Wren, Anthony W; Curran, Declan J; Hornez, Jean-Christophe; Mark R, Towler

    2013-05-01

    The effects of two strontium (Sr) additions, 5% and 10% of the total calcium (Ca) content, on the phase assemblage and Weibull statistics of hydroxyapatite (HA) are investigated and compared to those of undoped HA. Sintering was carried out in the range of 900-1200 °C in steps of 1000 °C in a conventional furnace. Sr content had little effect on the mean particulate size. Decomposition of the HA phase occurred with Sr incorporation, while β-TCP stabilization was shown to occur with 10% Sr additions. Porosity in both sets of doped samples was at a comparable level to porosity in the undoped HA samples, however the 5% Sr-HA samples displayed the greatest reduction in porosity with increasing temperature while the porosity of the 10% Sr-HA samples remain relatively constant over the full sintering temperature range. The undoped HA samples displayed the greatest Weibull strengths and the porosity was determined to be the major controlling factor. However, with the introduction of decompositional phases in the Sr-HA samples, the dependence of strength on porosity is reduced and the phase assemblage becomes the more dominant factor for Weibull strength. The Weibull modulus is relatively independent of the porosity in the undoped HA samples. The 5% Sr-HA samples experience a slight increase in Weibull modulus with porosity, indicating a possible relationship between the parameters. However the 10% Sr-HA samples show the highest Weibull modulus with a value of approximately 15 across all sintering temperatures. It is postulated that this is due to the increased amount of surface and lattice diffusion that these samples undergo, which effectively smooths out flaws in the microstructure, due to a saturation of Sr content occurring in grain boundary movement. PMID:23524073

  13. KrF excimer laser precision machining of hard and brittle ceramic biomaterials.

    PubMed

    Huang, Yao-Xiong; Lu, Jian-Yi; Huang, Jin-Xia

    2014-06-01

    KrF excimer laser precision machining of porous hard-brittle ceramic biomaterials was studied to find a suitable way of machining the materials into various desired shapes and sizes without distorting their intrinsic structure and porosity. Calcium phosphate glass ceramics (CPGs) and hydroxyapatite (HA) were chosen for the study. It was found that KrF excimer laser can cut both CPGs and HA with high efficiency and precision. The ablation rates of CPGs and HA are respectively 0.081 µm/(pulse J cm(-2)) and 0.048 µm/(pulse  J cm(-2)), while their threshold fluences are individually 0.72 and 1.5 J cm(-2). The cutting quality (smoothness of the cut surface) is a function of laser repetition rate and cutting speed. The higher the repetition rate and lower the cutting speed, the better the cutting quality. A comparison between the cross sections of CPGs and HA cut using the excimer laser and using a conventional diamond cutting blade indicates that those cut by the excimer laser could retain their intrinsic porosity and geometry without distortion. In contrast, those cut by conventional machining had distorted geometry and most of their surface porosities were lost. Therefore, when cutting hard-brittle ceramic biomaterials to prepare scaffold and implant or when sectioning them for porosity evaluation, it is better to choose KrF excimer laser machining. PMID:24784833

  14. Characterization and inhibitive study of gel-grown hydroxyapatite crystals at physiological temperature

    NASA Astrophysics Data System (ADS)

    Parekh, Bharat; Joshi, Mihir; Vaidya, Ashok

    2008-04-01

    Hydroxyapatite is very useful for various biomedical applications, due to its chemical similarity with mineralized bone of human. Hydroxyapatite is also responsible for arthropathy (joint disease). In the present study, the growth of hydroxyapatite crystals was carried out by using single-diffusion gel growth technique in silica hydro gel media, at physiological temperature. The growth of hydroxyapatite crystals under slow and controlled environment in gel medium can be simulated in a simple manner to the growth in human body. The crystals, formed in the Liesegang rings, were characterized by powder XRD, FTIR and dielectric study. The diffusion study is also carried out for the hydroxyapatite crystals using the moving boundary model. The inhibitive influence of various Ayurvedic medicinal plant extracts such as Boswellia serrata gum resin , Tribulus terrestris fruits, Rotula aquatica roots, Boerhaavia diffusa roots and Commiphora wightii, on the growth of hydroxyapatite was studied. Roots of R. aquatica and B. diffusa show some inhibition of the hydroxyapatite crystals in vitro. This preclinical study will be helpful to design the therapy for prevention of hydroxyapatite-based ailments.

  15. Containment of uranium in the proposed Egyptian geologic repository for radioactive waste using hydroxyapatite.

    SciTech Connect

    Moore, Robert Charles; Hasan, Ahmed Ali Mohamed; Headley, Thomas Jeffrey; Sanchez, Charles Anthony; Zhao, Hongting; Salas, Fred Manuel; Hasan, Mahmoud A.; Holt, Kathleen Caroline

    2003-08-01

    Currently, the Egyptian Atomic Energy Authority is designing a shallow-land disposal facility for low-level radioactive waste. To insure containment and prevent migration of radionuclides from the site, the use of a reactive backfill material is being considered. One material under consideration is hydroxyapatite, Ca{sub 10}(PO{sub 4}){sub 6}(OH){sub 2}, which has a high affinity for the sorption of many radionuclides. Hydroxyapatite has many properties that make it an ideal material for use as a backfill including low water solubility (K{sub sp} > 10{sup -40}), high stability under reducing and oxidizing conditions over a wide temperature range, availability, and low cost. However, there is often considerable variation in the properties of apatites depending on source and method of preparation. In this work, we characterized and compared a synthetic hydroxyapatite with hydroxyapatites prepared from cattle bone calcined at 500 C, 700 C, 900 C and 1100 C. The analysis indicated the synthetic hydroxyapatite was similar in morphology to 500 C prepared cattle hydroxyapatite. With increasing calcination temperature the crystallinity and crystal size of the hydroxyapatites increased and the BET surface area and carbonate concentration decreased. Batch sorption experiments were performed to determine the effectiveness of each material to sorb uranium. Sorption of U was strong regardless of apatite type indicating all apatite materials evaluated. Sixty day desorption experiments indicated desorption of uranium for each hydroxyapatite was negligible.

  16. Containment of uranium in the proposed Egyptian geologic repository for radioactive waste using hydroxyapatite.

    SciTech Connect

    Moore, Robert Charles; Hasan, Ahmed Ali Mohamed; Headley, Thomas Jeffrey; Sanchez, Charles Anthony; Zhao, Hongting; Salas, Fred Manuel; Hasan, Mahmoud A.; Holt, Kathleen Caroline

    2004-04-01

    Currently, the Egyptian Atomic Energy Authority is designing a shallow-land disposal facility for low-level radioactive waste. To insure containment and prevent migration of radionuclides from the site, the use of a reactive backfill material is being considered. One material under consideration is hydroxyapatite, Ca{sub 10}(PO{sub 4}){sub 6}(OH){sub 2}, which has a high affinity for the sorption of many radionuclides. Hydroxyapatite has many properties that make it an ideal material for use as a backfill including low water solubility (K{sub sp}>10{sup -40}), high stability under reducing and oxidizing conditions over a wide temperature range, availability, and low cost. However, there is often considerable variation in the properties of apatites depending on source and method of preparation. In this work, we characterized and compared a synthetic hydroxyapatite with hydroxyapatites prepared from cattle bone calcined at 500 C, 700 C, 900 C and 1100 C. The analysis indicated the synthetic hydroxyapatite was similar in morphology to 500 C prepared cattle hydroxyapatite. With increasing calcination temperature the crystallinity and crystal size of the hydroxyapatites increased and the BET surface area and carbonate concentration decreased. Batch sorption experiments were performed to determine the effectiveness of each material to sorb uranium. Sorption of U was strong regardless of apatite type indicating all apatite materials evaluated. Sixty day desorption experiments indicated desorption of uranium for each hydroxyapatite was negligible.

  17. FORMATION OF CHLOROPYROMORPHITE IN A LEAD-CONTAMINATED SOIL AMENDED WITH HYDROXYAPATITE

    EPA Science Inventory

    To evaluate conversion of soil Pb to pyromorphite, a Pb contaminated soil collected adjacent to a historical smelter was reacted with hydroxyapatite in a traditional incubation experiment and in a dialysis system in which the soil and hydroxyapatite solids were separated by a dia...

  18. Synthesis and release of trace elements from hollow and porous hydroxyapatite spheres

    NASA Astrophysics Data System (ADS)

    Xia, Wei; Grandfield, Kathryn; Schwenke, Almut; Engqvist, Håkan

    2011-07-01

    It is known that organic species regulate fabrication of hierarchical biological forms via solution methods. However, in this study, we observed that the presence of inorganic ions plays an important role in the formation and regulation of biological spherical hydroxyapatite formation. We present a mineralization method to prepare ion-doped hydroxyapatite spheres with a hierarchical structure that is free of organic surfactants and biological additives. Porous and hollow strontium-doped hydroxyapatite spheres were synthesized via controlling the concentration of strontium ions in a calcium and phosphate buffer solution. Similarly, fluoride and silicon-doped hydroxyapatite spheres were synthesized. While spherical particle formation was attainable at low and high temperature for Sr-doped hydroxyapatite, it was only possible at high temperature in the F/Si-doped system. The presence of inorganic ions not only plays an important role in the formation and regulation of biological spherical hydroxyapatite, but also could introduce pharmaceutical effects as a result of trace element release. Such ion release results showed a sustained release with pH responsive behavior, and significantly influenced the hydroxyapatite re-precipitation. These ion-doped hydroxyapatite spheres with hollow and porous structure could have promising applications as bone/tooth materials, drug delivery systems, and chromatography supports.

  19. Effect of silicon content on the sintering and biological behaviour of Ca10(PO4)(6-x)(SiO4)x(OH)(2-x) ceramics.

    PubMed

    Palard, Mickaël; Combes, Julien; Champion, Eric; Foucaud, Sylvie; Rattner, Aline; Bernache-Assollant, Didier

    2009-05-01

    Silicated hydroxyapatite powders (Ca10(PO4)(6-x)(SiO4)x(OH)(2-x); Si(x)HA) were synthesized using a wet precipitation method. The sintering of Si(x)HA ceramics with 0 < or = x < or = 1 was investigated. For 0 < or = x < or = 0.5, the sintering rate and grain growth decreased slightly with the amount of silicate. For larger amounts, the sintering behaviour differed with the formation of secondary phases before total densification. Sintering parameters (temperature and time) were adjusted to each composition to produce dense materials having similar microstructure without formation of these secondary phases. Dense ceramics made of pure hydroxyapatite and Si(x)HA containing various amounts of silicate (up to x = 0.6) were biologically tested in vitro with human osteoblast-like cells. The proliferation of cells on the surface of the ceramics increased up to 5 days of culture, indicating that the materials were biocompatible. However, the silicon content did not influence the cell proliferation. PMID:19036652

  20. OXYGEN TRANSPORT CERAMIC MEMBRANES

    SciTech Connect

    Dr. Sukumar Bandopadhyay; Dr. Nagendra Nagabhushana

    2003-01-01

    In the present quarter, the possibility of using a more complex interfacial engineering approach to the development of reliable and stable oxygen transport perovskite ceramic membranes/metal seals is discussed. Experiments are presented and ceramic/metal interactions are characterized. Crack growth and fracture toughness of the membrane in the reducing conditions are also discussed. Future work regarding this approach is proposed are evaluated for strength and fracture in oxygen gradient conditions. Oxygen gradients are created in tubular membranes by insulating the inner surface from the reducing environment by platinum foils. Fracture in these test conditions is observed to have a gradient in trans and inter-granular fracture as opposed to pure trans-granular fracture observed in homogeneous conditions. Fracture gradients are reasoned to be due to oxygen gradient set up in the membrane, variation in stoichiometry across the thickness and due to varying decomposition of the parent perovskite. The studies are useful in predicting fracture criterion in actual reactor conditions and in understanding the initial evolution of fracture processes.