• Clinics in Shoulder and Elbow
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• v.27 no.1
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• pp.117-125
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• 2024

While shoulder hemiarthroplasty is still used to treat young patients with shoulder pathology, the use of this procedure has substantially declined in recent years due to its significant complication profile. Glenoid wear with arthrosis is one of the major postoperative complications following shoulder hemiarthroplasty, and efforts to prevent this complication led many scientists to explore alternative weight-bearing surfaces on arthroplasty implants to decrease joint wear and improve patient outcomes. Pyrolytic carbon, or pyrocarbon, is a material that has better biocompatibility, survivorship, strength, and wear resistance compared to the materials used in traditional shoulder hemiarthroplasty. Pyrocarbon implants have been used in orthopedics for over 50 years; recently, their utility in shoulder hemiarthroplasty has garnered much interest. The purpose behind the use of pyrocarbon in shoulder hemiarthroplasty is to decrease the risk of progressive glenoid wear, especially in young active patients in whom joint preservation is important. Promising survivorship and outcomes have been demonstrated by recent studies, including limited glenoid wear following pyrocarbon hemiarthroplasty. Nevertheless, these clinical studies have been limited to relatively small case series with limited long-term follow-up. Accordingly, additional research and comparative studies need to be conducted in order to properly assess the therapeutic efficacy and value of pyrocarbon hemiarthroplasty.

• Nuclear Engineering and Technology
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• v.41 no.5
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• pp.715-722
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• 2009

A model to predict failure of designed-to-fail (dtf) fuel particles is discussed. The dtf fuel under study consisted of a uranium oxycarbide kernel coated with a single pyrocarbon seal coat. Coating failure was assumed to be due to fission gas recoil and knockout mechanisms and direct diffusive release of fission gas from the kernel, which acted to increase pressure and stress in the pyrocarbon layer until it ruptured. Predictions of dtf fuel failure using General Atomics' particle fuel performance code for HRB-17/18 and HFR-B1 irradiation tests were reasonably accurate; however, the model could not predict the failure for COMEDIE BD-1. This was most likely due to insufficient information on reported particle fuel failure at the beginning.

• Transactions of the Korean hydrogen and new energy society
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• v.13 no.2
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• pp.101-109
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• 2002

This work was focused on the thermal decomposition of methane into hydrogen and carbon black without emitting carbon dioxide. Extensive experimental investigation on the thermal decomposition of methane has been carried out using a continuous flow reaction system with tubular reactor. The experiments were conducted at the atmospheric pressure condition in the wide range of temperature ($950-1150^{\circ}C$) and flow rate (250 - 1500 ml/min) in order to study their dependency on hydrogen yield. During the experiments the carbon black was successfully recovered as an useful product. Undesirable pyrocarbon was also formed as solid film, which was deposited on the inside surface of tubular reactor. The film of pyrocarbon in the reactor wall became thicker and thicker, finally blocking the reactor. The design of an efficient reactor which can effectively suppress the formation of pyrocarbon was thought to be one of the most important subjects in the thermal cracking of methane.

• Carbon letters
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• v.6 no.2
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• pp.101-105
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• 2005

Like bamboo-sprouts after rains, numerous sub${\mu}m$-sized pyrocarbon whiskers growth on the Mullite ($3Al_2O_3{\cdot}2H_2O$) substrate could be observed through a looking glass during methane pyrolysis at the temperature of $1050^{\circ}C$ in this study. If the surface of substrate would be scrubbed strongly with iron metals, then finely sticked iron particles were more effective catalytic for nm-sized whisker growth. Numerous fine flakes of pyrolytic carbon were hanging by invisible nm-whiskers as like as small spiders hanging by a spiderweb. This is the identification of nm-sized whisker growth. Therefore if the pyrolysis would be stopped at the initial stage of the whisker growth, the primary lengthening growth was nm-sized whisker. So could we vary arbitrarily sizes of whisker from nm- to ${\mu}m$-sizes. But ${\mu}m$- and nm-whiskers grown with the different growth mechanism; the former was straight and the latter has twigs, The lengthening growth of whisker was depended on the flow pattern pyrolysis species on the active sites of substrate and on the growth duration. We could obtained straight whisker length of 10~20 ${\mu}m$/min during the primary growth and laboratory spiral whisker of 30~40 ${\mu}m$-diameter/hr during the secondary growth.

• Clean Technology
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• v.10 no.4
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• pp.203-213
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• 2004

Natural gas thermal decomposition method is the technology of converting natural gas (methane) into hydrogen and carbon at high temperature. The most advantage of thermal decomposition method is that hydrogen and carbon can be produced without emitting carbon dioxide. In this study, the generation of hydrogen and carbon was investigated by this natural gas (methane) thermal decomposition method. We found that pyrocarbon was created on the surface of reactor, carbon black was deposited on the pyrocarbon and final plugging phenomenon took place. To solve this problem, we tried several attempts such as introduction of double pipe reactor instead of single pipe reactor or oxidization of carbon black using $O_2$ or $CO_2$ at regular intervals of reaction. Therefore, some plugging phenomenon was resolved by this methods. Also, carbon particle size was measured by SEM (Scanning Electron Microscope) image and the size was about 200 nm.

• Korean Chemical Engineering Research
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• v.46 no.6
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• pp.1025-1028
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• 2008

With the assistance of thermal pyrolysis process for hydrocarbon gases, the formation and growth of particulate carbon was systematically investigated as a function of temperature in the gas phase. The yield and average size of pyrocarbon particles were found to increase with increasing pyrolysis temperature. The difference in the yield of carbon particles generated by pyrolizing acetylene and ethylene gas posed a question about the role of hydrogen in the pyrolysis of hydrocarbon gases. In order to reveal the role of hydrogen, controlled amount of hydrogen was added to the acetylene pyrolysis, and then hydrogen addition was observed to suppress the formation and growth of carbon particles. One can control the size of pyrocarbon particles by controlling the hydrogen gas addition.

• Transactions of the Korean hydrogen and new energy society
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• v.14 no.2
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• pp.105-113
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• 2003

The pyrolysis for production of hydrogen and high quality carbon black from natural gas were studied. The reactivities in tubular reactor and FVR(free volume reactor) for the methane pyrolysis were compared, in order to prevent the formation of undesirable carbon product such as pyrocarbon, the FVR was designed. The hydrogen yield and the formation of carbon black from methane pyrolysis in this reactor were investigated at temperature range between 1443 and 1576K. From the result of TEM (transmission electron microscopy) analysis, it was confirmed that the CFC(catalytic filamentous carbon) was formed without pyrocarbon.

• Journal of the Korean Ceramic Society
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• v.33 no.8
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• pp.935-941
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• 1996

Two-dimensional carbon/carbon preforms made of PAN-based carbon yarn and phenolic resin were densified with pyrolysis of propane by pulse chemical vapor infiltration where repeated the cycle of gas introduction residence and evacuation. Maximim density increment was 14% when infiltration temperature and time were 100$0^{\circ}C$ and 21.25 hrs respectively. The distribution of deposits of pyrocarbon by this process has been occurred uniformly in the bottom middle and top of carbon/carbon composite preform Pulse CVI with residence is most effective in increasing density and shortening infiltration time among isothermal CVI and pulse CVI with and without residence.

• Nuclear Engineering and Technology
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• v.39 no.5
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• pp.603-616
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• 2007

Roy Huddle, having invented the coated particle in Harwell 1957, stated in the early 1970s that we know now everything about particles and coatings and should be going over to deal with other problems. This was on the occasion of the Dragon fuel performance information meeting London 1973: How wrong a genius be! It took until 1978 that really good particles were made in Germany, then during the Japanese HTTR production in the 1990s and finally the Chinese 2000-2001 campaign for HTR-10. Here, we present a review of history and present status. Today, good fuel is measured by different standards from the seventies: where $9*10^{-4}$ initial free heavy metal fraction was typical for early AVR carbide fuel and $3*10^{-4}$ initial free heavy metal fraction was acceptable for oxide fuel in THTR, we insist on values more than an order of magnitude below this value today. Half a percent of particle failure at the end-of-irradiation, another ancient standard, is not even acceptable today, even for the most severe accidents. While legislation and licensing has not changed, one of the reasons we insist on these improvements is the preference for passive systems rather than active controls of earlier times. After renewed HTGR interest, we are reporting about the start of new or reactivated coated particle work in several parts of the world, considering the aspects of designs/ traditional and new materials, manufacturing technologies/ quality control quality assurance, irradiation and accident performance, modeling and performance predictions, and fuel cycle aspects and spent fuel treatment. In very general terms, the coated particle should be strong, reliable, retentive, and affordable. These properties have to be quantified and will be eventually optimized for a specific application system. Results obtained so far indicate that the same particle can be used for steam cycle applications with $700-750^{\circ}C$ helium coolant gas exit, for gas turbine applications at $850-900^{\circ}C$ and for process heat/hydrogen generation applications with $950^{\circ}C$ outlet temperatures. There is a clear set of standards for modem high quality fuel in terms of low levels of heavy metal contamination, manufacture-induced particle defects during fuel body and fuel element making, irradiation/accident induced particle failures and limits on fission product release from intact particles. While gas-cooled reactor design is still open-ended with blocks for the prismatic and spherical fuel elements for the pebble-bed design, there is near worldwide agreement on high quality fuel: a $500{\mu}m$ diameter $UO_2$ kernel of 10% enrichment is surrounded by a $100{\mu}m$ thick sacrificial buffer layer to be followed by a dense inner pyrocarbon layer, a high quality silicon carbide layer of $35{\mu}m$ thickness and theoretical density and another outer pyrocarbon layer. Good performance has been demonstrated both under operational and under accident conditions, i.e. to 10% FIMA and maximum $1600^{\circ}C$ afterwards. And it is the wide-ranging demonstration experience that makes this particle superior. Recommendations are made for further work: 1. Generation of data for presently manufactured materials, e.g. SiC strength and strength distribution, PyC creep and shrinkage and many more material data sets. 2. Renewed start of irradiation and accident testing of modem coated particle fuel. 3. Analysis of existing and newly created data with a view to demonstrate satisfactory performance at burnups beyond 10% FIMA and complete fission product retention even in accidents that go beyond $1600^{\circ}C$ for a short period of time. This work should proceed at both national and international level.

• Maxillofacial Plastic and Reconstructive Surgery
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• v.37
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• pp.34.1-34.14
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• 2015

Background: Over the past 30-40 years, various carbon implant materials have become more interesting, because they are well accepted by the biological environment. The traditional carbon-based polymers give rise to many complications. The polymer complication may be eliminated through carbon fibres bound by pyrocarbon (carbon/carbon). The aim of this study is to present the long-term clinical results of carbon/carbon implants, and the results of the scanning electron microscope and energy dispersive spectrometer investigation of an implant retrieved from the human body after 8 years. Methods: Mandibular reconstruction (8-10 years ago) was performed with pure (99.99 %) carbon implants in 16 patients (10 malignant tumours, 4 large cystic lesions and 2 augmentative processes). The long-term effect of the human body on the carbon/carbon implant was investigated by comparing the structure, the surface morphology and the composition of an implant retrieved after 8 years to a sterilized, but not implanted one. Results: Of the 16 patients, the implants had to be removed earlier in 5 patients because of the defect that arose on the oral mucosa above the carbon plates. During the long-term follow-up, plate fracture, loosening of the screws, infection or inflammations around the carbon/carbon implants were not observed. The thickness of the carbon fibres constituting the implants did not change during the 8-year period, the surface of the implant retrieved was covered with a thin surface layer not present on the unimplanted implant. The composition of this layer is identical to the composition of the underlying carbon fibres. Residual soft tissue penetrating the bulk material between the carbon fibre bunches was found on the retrieved implant indicating the importance of the surface morphology in tissue growth and adhering implants. Conclusions: The surface morphology and the structure were not changed after 8 years. The two main components of the implant retrieved from the human body are still carbon and oxygen, but the amount of oxygen is 3-4 times higher than on the surface of the reference implant, which can be attributed to the oxidative effect of the human body, consequently in the integration and biocompatibility of the implant. The clinical conclusion is that if the soft part cover is appropriate, the carbon implants are cosmetically and functionally more suitable than titanium plates.