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41.
BACKGROUND: Defects in the skull have presented difficult reconstructive problems. Recently glass-ionomer cement and preformed. implants have been used to repair bony defects in the skull base and in cranio-facial surgery. Three patients are reported to illustrate possible applications for this new material. METHODS: Ionocap cement and Ionoroc-skull standardized implants have been used. The cement is available as a two component blister pack. When mixed and blended a gel is produced which can be worked for approximately 5 min before hardening. It can then be contoured and drilled to the required shape. The resultant material is biocompatible and biostable, is non-toxic and permanently bonds to bone with no increase in temperature or shrinkage. RESULTS: The material has been used to fill the temporal defect left by transplantation of the temporalis muscle for oral reconstruction, the anterior and lateral walls of the maxilla and following craniofacial resection, the posterior wall of the frontal sinus and anterior skull base. CONCLUSIONS: Three patients with different reconstructive problems have been presented to illustrate the use of an alloplastic material that has a tensile strength similar to bone and firmly adheres to it. The material was found to be safe and easy to use. All three patients have now been followed for 12 months with no adverse affects. 相似文献
42.
介绍了高温超导红外探测器电极材料的选择和制备。选用先蒸、后蒸金,再合金化的电极工艺。芯片装配成器件后,器件性能稳定,膜层牢固,接触电阻小。 相似文献
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PO Freskgard LC Petersen DA Gabriel X Li E Persson 《Canadian Metallurgical Quarterly》1998,37(20):7203-7212
The binding of the multidomain protein factor VIIa (fVIIa) to tissue factor provides the interprotein communication necessary to make fVIIa an efficient catalyst of the initial event in the extrinsic pathway of blood coagulation. We have investigated the stability of individual domains in fVIIa and the influence of Ca2+ and an irreversible active-site inhibitor (FFR-chloromethyl ketone). Equilibrium guanidine hydrochloride (GuHCl)-induced unfolding monitored by tryptophan fluorescence and far-UV circular dichroism (CD) demonstrated that the gamma-carboxyglutamic acid (Gla) domain unfolds at 0.3 M GuHCl and the serine protease (SP) domain at 3 M GuHCl and that Ca2+ is a prerequisite for the formation of an ordered, compact structure in the Gla domain. The loss of amidolytic activity coincides with the first transition, which is stabilized by the active-site inhibitor, and a change in the environment of the active site is demonstrated using a fluorescent inhibitor (DEGR-chloromethyl ketone). Thermal unfolding monitored by differential scanning calorimetry (DSC) reveals that Ca2+ stabilizes the SP domain slightly, increasing the unfolding temperature by 2.7 degrees C. In addition, Ca2+ is required for a large enthalpy change concomitant with unfolding of the Gla domain, and this unfolding enthalpy is only detectable in the presence of the SP domain, indicating some kind of interaction between these domains. Thermal unfolding measured by CD indicates secondary structural changes at the same temperature as the heat absorption in the DSC but only when both the Gla domain and the SP domain are present together with Ca2+ ions. Taken together, these results indicate a Ca2+-dependent interaction between the Gla domain and the SP domain, implying a high degree of flexibility of the domains in free fVIIa. It is also shown that the epidermal growth factor-like domains are stable at elevated temperatures and high GuHCl concentrations. Moreover, already at physiological temperature, subtle structural changes take place which influence the overall shape of fVIIa and are detrimental to its enzymatic activity. 相似文献
44.
In this paper,we address the need for better hands-on learning materials in computing education and the need for integrating mobile computing education into computing curricular.We propose an innovative learning approach that uses state-of-the-art mobile computing technologies and devices to design a highly accessible and real-world relevant hands-on labware for computing education.The labware employs a modular design such that the learning materials can both be combined together into a single course of mobile program development and be integrated into the related computing courses as building blocks.The labware will help students understand the concepts,improve their problem solving skills,and prepare them for the mobile computing industrial workforce.The pilot modules of the labware have been presented to undergraduate students and have received positive feedbacks. 相似文献
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针对初学者在学习Access数据库中遇到的困难,设计了三个教学案例,介绍报表中计算控件的使用、if语句的语法格式和通配符“?”和“’,的使用.对于提高Access数据库的教学效果有一定的参考价值。 相似文献
48.
Lyndsay A. Cartwright Sue Hayes Douglas C. Tozer Dan Clayton Mary-Ann Burns Dena Lewis Noah Gaetz Namrata Shrestha 《Journal of Great Lakes research》2021,47(2):273-282
Beneficial use impairments (BUIs) under the Great Lakes Water Quality Agreement identify environmental issues requiring remedial action within the Great Lakes Areas of Concern (AOCs). We conducted this study to support the assessment of the wildlife component of BUI 3: degradation of fish and wildlife populations. We compared bird and amphibian (frogs and toads) data from the Toronto and Region Conservation Authority’s Terrestrial Long-term Monitoring Program in the Toronto and Region AOC to an adjacent, but otherwise similar, reference watershed, Duffins Creek. Twelve of 13 targets were met within the AOC for forest bird, wetland bird, meadow bird and amphibian populations based on averages of mean annual values at sites within the AOC that were within two standard deviations of averages at sites in the Duffins Creek reference watershed between 2008 and 2017. Even though wildlife populations within the AOC were within the normal range of variability expected from a reference watershed, they were often at lower levels than within the Duffins Creek reference watershed. In addition, forest bird and amphibian populations were negatively affected by urbanization within the AOC and meadow bird indices declined. We conclude that while wildlife populations within the AOC currently meet targets for BUI 3, they continue to be negatively impacted by numerous stressors that are primarily related to past and ongoing urbanization. Thus, continued restoration of wildlife habitat and protection of existing habitat within the AOC is highly recommended. 相似文献
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