HDPE／PS／HDPE－g－PS合金的相容性和力学性能研究

用自制接枝共聚物ＧＲ－Ⅰ、ＧＲ－Ⅱ相容剂研究其对ＨＤＰＥ／ＰＳ共混物相容性和力学性能的影响。通过ＳＥＭ、ＤＭＡ、ＤＳＣ和力学性能测试表征，表明在ＨＤＰＥ／ＰＳ共混中加入这些相容剂其相容性和力学性能有一定提高     

HDPE／PS／HDPE—g—PS合金的相容性和力学性能研究

用自制接枝共聚物ＧＲ－Ｉ、ＧＲ－Ⅱ相容剂研究其对ＨＤＰＥ／ＰＳ共混物相容性和力学性能的影响。通过ＳＥＭ、ＤＭＡ和力学性能测试表征，表明在ＨＤＰＥ／ＰＳ共混中加入这些相容剂其相容性和力学性能有一定提高。     

RPS/PE反应性共混研究

用ＩＲ、ＤＳＣ、ＧＰＣ研究了侧基含有过氧键的活性聚苯乙烯与聚乙烯之间的反频，用ＳＥＭ观察了共混物的断面形态。结果表明，ＲＰＳ／ＰＥ共混反应中生成ＰＳ－ｇ－ＰＥ，对ＰＥ／ＰＳ共混物具有增容作用，提高了共混物的力学性能。     

Si3N4薄膜的DC—PCVD沉积工艺及结构

用不附加另外电源的ＤＣ－ＰＣＶＤ装置沉积Ｓｉ３Ｎ４薄膜，，ＸＲＤ ＴＥＭ检查出这种Ｓｉ３Ｎ４是非晶态、ＩＲ，ＡＥＳ验证这种薄膜的主要成分是Ｓｉ３Ｎ４、ＴＥＭ与ＯＭ研究 薄膜组织结构。     

助烧剂对热压Si3N4基陶瓷组织结构的影响

用ＸＲＤ，ＳＥＭ，ＴＥＭ分析了用Ｙ２Ｏ３＋Ａｌ２Ｏ３及Ｙ２Ｏ３＋ＡｌＮ做助烧剂的两种热压Ｓｉ３Ｎ４基陶瓷的组织结构，用ＥＤＸＡ分析了Ｓｉ，Ａｌ，Ｙ等元素的含量。结果表明，两种Ｓｉ３Ｎ４都是由长柱状β相组成；     

超高韧半晶聚合物PP多相体系的结构及脆韧转变的研究

通过严格控制工艺条件，得到了不同分散相含量和不同粒径的ＰＰ／ＥＰＤＭ／ＨＤＰＥ和ＰＰ／ＥＰＤＭ共混体。利用ＳＥＭ分析了ＰＰ／ＥＰＤＭ／ＨＤＰＥ的结构特点，通过测量Ｉｚｏｄ缺口冲击强度，得到了ＰＰ／ＥＰＤＭ／ＨＤＰＥ的脆韧转变主曲线，证明其符合脆韧性转变规律；同时利用ＳＥＭ照片，分析了主曲线不同区域的增韧机理。     

溶胶-凝胶法有机-无机精细复合材料P(VDF/TeFE)-SiO_2的制备与显微结构

用溶胶－凝胶法制备了有机－无机精细复合材料Ｐ（ＶＤＦ／ＴｅＦＥ）－ＳｉＯ２。利用水解－聚合反应由正硅酸乙脂（ＴＥＯＳ）合成ＳｉＯ２溶胶，乙醇作溶剂，盐酸作催化剂。将Ｐ（ＶＤＦ／ＴｅＦＥ）溶于丙酮，并与ＳｉＯ２溶胶均匀混合。凝胶后经干燥和热处理得到有机－无机精细复合材料Ｐ（ＶＤＦ／ＴｅＦＥ）－ＳｉＯ２。用红外光谱分析、扫描电镜分析、差示扫描热分析和热失重分析对有机－无机精细复合材料Ｐ（ＶＤＦ／ＴｅＦＥ）－ＳｉＯ２进行了显微结构表征。     

PP/EPDM/DDCP共混体系的流变性能-亚微形态-力学性能研究

采用ＥＰＤＭ作为增韧剂，ＤＤＣＰ作为流动改性剂，通过双螺杆挤出机共混制成ＰＰ／ＥＰＤＭ／ＤＤＣＰ高分子合金，并测试其力学性能；研究其共混组成对流变性能的影响；用ＳＥＭ对所制备的合金的亚微形态进行了观察。结果表明，合金的缺口冲击强度和力学性能得到显著提高，其冲击样条断裂面上呈现明显韧性断裂特征；ＤＤＣＰ的加入明显地改善了流动性；填料可使合金的刚性得到加强。     

沉淀法合成高比表面积超细SiO2

以水玻璃和盐酸为原料，采用化学沉淀法制备出多孔型、高比表面积、超细ＳｉＯ２，用ＢＥＴ、ＸＲＤ、ＳＥＭ、ＤＴＡ－ＴＧＡ等手段对其性能进行了表征，结果表明，所制得的多孔型ＳｉＯ２经表面积可达１０００ｍ＾２／ｇ以上，孔分布均匀，粒径小，具有许多特殊的性能。     

不同组份PbO2-MnO2催化层钛基阳极的研究

本文用热分解方法制备了ＰｂＯ２－ＭｎＯ２混合金属氧化物阳极，对电极进行了ＥＤＳ、ＳＥＭ、ＸＲＤ研究，测定了电极在１ｍｏｌ／ＬＨ２ＳＯ４溶液中的使用寿命和动力学参数，结果表明：所制备电极具有优良的电催化活性和电化学稳定性。     

Stress distribution in dental implant with elastomeric stress barrier

Dental implant has been used and studied for the replacement of missing teeth for many years. It has been well known that the success of dental implant is heavily dependent on initial stability and long-term Osseointegration due to optimal stress distribution in the surrounding bones. For this reason, the search of the rational solutions to reduce these stresses has become an important issue in this field. Alternatives to reduce the forces transmitted to implants have been studied, including variations in implant positioning, implant design, prosthesis shape, occlusal requirements, prosthetic components and prosthetic materials. Thus, a new concept of adding a bio-elastomer to the prosthetic components of implant system was interposed between the abutment and the framework crown in order to damp the occlusive shocks and to attenuate the stress concentrated at the implant/bone interface. The new implant system design was assessed by the three dimensional finite element techniques using ABAQUS program to study the effect of elastomer material under an occlusal load on the induced equivalent von Mises interface stresses. These stresses were compared with those provoked by the standardized implant. The von Mises stress distribution indicated that stress was maximal around the top of the implant with varying intensities in the different loading cases. The stress was highest in the cortical bone at the neck of implant and lowest in the cancellous bone. Overall, the novel implant provoked lower interface stresses only in the cortical bone due to the stress shielding effect of the elastomeric stress barrier.     

Fabrication and characterization of porous hydroxyapatite ocular implant followed by an<Emphasis Type="Italic">in vivo</Emphasis> study in dogs

Porous hydroxyapatite ocular implant was fabricated by a novel and simple method using hydroxyapatite powder synthesized in the laboratory. The porosity and pore size of the implant were controlled to make it light in weight as well as suitable for rapid vascularization after implantation. The implant was characterized by X-ray diffraction studies, infrared spectra and chemical analysis for phase purity and chemical composition. The pore morphology and pore size distribution of the samples were investigated by scanning electron microscope (SEM). Thereafter, efficacy of the implant was examined byin vivo study in dogs. Clinical, haematological and radiological studies indicated the suitability of the implant for replacement of the lost eye of human patients.     

No biological advantage with a low temperature curing versus a conventional bone cement: an experimental, mechanical and histomorphometrical study in the rabbit tibia

Both tibial marrow cavities of 12 rabbits were evacuated and filled with curing bone cement. In one of the tibias conventional curing bone cement (Simplex P®) was injected, while the other tibia of the same animal was filled with a low temperature curing bone cement (Boneloc®). Three titanium implants were inserted along the proximal metaphysis of each tibia. Eight weeks after insertion the most distal implant in each tibia was removed while recording the removal torque. The implant was then once again screwed home into its bone bed. The animals were sacrificed 16 weeks after implant insertion. The previously removed implant and another implant in each tibia were then both removed while recording the removal torque. The third implant in each tibia was cut out en bloc with surrounding tissue and processed for ground section. We found no statistical differences in the mechanical or the histomorphometric evaluation of implant integration between the two cements, indicating that the low temperature curing bone cement does not result in a significantly different bone response from that of a conventional acrylic cement. ©©1999©Kluwer Academic Publishers     

Finite element analysis of femoral components paper III – hip joints

Finite element analysis of the hip implant is conducted in this paper for representative femoral cross-section geometries and development of stress in the presence of bone cement is elucidated. Differences in cement stresses generated by varying implant cross-sections were compared with conventional features derived from representative implants. The analysis was performed under idealized implant assemblies by constraining the implant movement in the assembly. The cross-sections and implant geometries used are generic and intended to be representative of available geometries. This paper is a part of student research projects, prepared from a series of activities in biomedical implant research currently underway at Ohio Northern and Arkansas Tech Universities.     

Preparation of an electrodeposited hydroxyapatite coating on titanium substrate suitable for in-vivo applications

In this paper the porous hydroxyapatite coating on Ti implant materials was prepared by the process of electrodeposition, hydrothermal and sinter. The surface morphology, bond strength and thickness of HA coatings were investigated by SEM, AFM, and its biocompatibility was evaluated by cytotoxicity experiments and implant experiments, respectively. Results showed that (1) The HA coatings was 50 μm thickness and adhered on the Ti substrate strongly, which bond strength reached 38MPa. AFM analysis showed that the HA coating was porous structure, in which the mean pore size was 236.5 μm, (2) Cytotoxicity experiments and implant experiments showed that HA-coated Ti implant materials has little cytotoxicity in vitro and little inflammatory reaction in vivo, and there were no statistically disparity between HA-coated Ti implant and titanium implant materials of clinical application (p > 0.05), which demonstrated that HA-coated Ti has a good biocompatibility.     

Electron microscopic investigation on the osteogenesis at titanium implant/bone marrow interface under masticatory loading

Electron microscopic investigation on osteogenetic process at the implant surface of threadless rod-type titanium implants with different surface roughness of Ra 0.4 ± 0.01 μm, Sm 2.6 ± 0.3 μm and Ra 2.0 ± 0.12 μm, Sm 36 ± 9.1 μm was performed at the early stage of 21 and 42 days post implantation into the jawbones of four beagles under the load bearing condition of functional mastication. The implant surfaces were covered with a blood clot and haematopoietic stem cells (HSC) including phagocytic monocytes immediately after the implantation. Successively, osteogenic stem cells (OSC) migrated from cortical and/or trabecular endosteum to the HSC-layer on the implant surface. The new bone formation at the implant/bone marrow interface was developed by collaboration of osteomediator cells (OMC) differentiated from monocytes of HSC and osteoblast phenotype cells of OSC derived from endosteum of cortical bone and/or trabecular. The new bone layer at the implant surface consisted of two layers, solution-mediated calcification layer of pseudo bone and cell (osteoblast) -mediated calcification layer of true bone. The pseudo bone was produced by solution-mediated calcification of OMC- and HSC-remnants near by the implant surface. The bone healing process at the implant/bone marrow interface depended upon two factors; the migration of OSC from cortical and/or trabecular endosteum to the implant surface and the healing potentiality. Topographic dependency upon the bone healing potential at implant/bone marrow interface was not confirmed in this experiment under the load bearing condition of functional mastication.     

SEM and EDS investigation of a pyrolytic carbon covered C/C composite maxillofacial implant retrieved from the human body after 8 years

The long term effect of the human body on a pyrolytic carbon covered C/C composite maxillofacial implant (CarBulat^Tm) was investigated by comparing the structure, the surface morphology and composition of an implant retrieved after 8 years to a sterilized, but not implanted one. Although 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. Calcium can only be detected on the surface as a trace element implying that the new layer is not formed by bone tissue. 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 to implants.     

In vivo response of strontium and zinc-based ionomeric cement implants in bone

In this study the osteoconductive properties of strontium based ionomeric cements (ICs) named, LG125 and LG119, as well as zinc-based ICs, designated by LG130 and LG132, were compared. Wet ICs were surgically implanted into the femora of weaned Wistar rats for 4 weeks. To assess the percentage osseointegration the perimeter of the implant and the perimeter of bone in contact with the implant were measured using a pointer (the length of bone/implant interfacial contact). Osteoconduction was determined by taking six points at random around the perimeter of each ionomeric rod measuring the thickness of newly formed bone. The degree of osteoconduction was taken as the average thickness of new bone produced on the implant surface. It was found that osteoconduction was greatest in the strontium based IC implant LG125. From these studies it can be concluded that the composition LG125 might provide a useful purpose as a bone cement.     

耳蜗植入术后X线摄影位置的探讨

目的:为评价耳蜗植入术后电极的形态、所处的空间位置和插入耳蜗的深度,设计符合临床诊断要求的最佳X线摄影方法。方法:随机选取20例人工耳蜗植入术后患儿,分别拍摄耳蜗正、侧位CR片,经测量、分析及临床选择,最终确定耳蜗正、侧位片摄影位置及角度。结果:20例图像均能显示耳蜗内植入的电极,其中2例显示电极略有重合,位置及角度欠佳,其余18例均能清晰显示电极数目及排列顺序。结论:耳蜗正、侧位可充分满足耳蜗植入术后检查的临床需要,而且具有摆位简单、快速和经济、辐射剂量小等优点,为临床术后评估手术质量的重要标准。     

Replacing the nucleus pulposus of the intervertebral disk: prediction of suitable properties of a replacement material using finite element analysis

An axisymmetric finite element model of a human lumbar disk was developed to investigate the properties required of an implant to replace the nucleus pulposus. In the intact disk, the nucleus was modeled as a fluid, and the annulus as an elastic solid. The Young's modulus of the annulus was determined empirically by matching model predictions to experimental results. The model was checked for sensitivity to the input parameter values and found to give reasonable behavior. The model predicted that removal of the nucleus would change the response of the annulus to compression. This prediction was consistent with experimental results, thus validating the model. Implants to fill the cavity produced by nucleus removal were modeled as elastic solids. The Poisson's ratio was fixed at 0.49, and the Young's modulus was varied from 0.5 to 100 MPa. Two sizes of implant were considered: full size (filling the cavity) and small size (smaller than the cavity). The model predicted that a full size implant would reverse the changes to annulus behavior, but a smaller implant would not. By comparing the stress distribution in the annulus, the ideal Young's modulus was predicted to be approximately 3 MPa. These predictions have implications for current nucleus implant designs. © 2001 Kluwer Academic Publishers