针状硅灰石对磷酸盐骨水泥性能的影响

以磷酸氢二钾和磷酸二氢钾为固化液,以磷酸四钙、α-磷酸三钙、磷酸氢钙、焦磷酸钙、羟基磷灰石和碳酸钙为原料合成骨水泥,向其添加针状硅灰石,研究了针状硅灰石对其性能的影响。结果表明,在磷酸钙骨水泥中添加针状硅灰石可以缩短凝结时间,提高抗压强度。当针状硅灰石的添加量为3%,骨水泥性能达到最佳;其初凝时间、终凝时间分别为14和28 min,样品在Ringer’s模拟液溶液中浸泡2周后抗压强度达49.23 MPa,浸泡液的pH值变化幅度小(7.1~7.8),在安全范围之内。     

以α-磷酸三钙和磷酸四钙为主要原料的磷酸盐骨水泥的制备及其性能比较

分别以α 磷酸三钙和磷酸四钙为基本原料,添加羟基磷灰石、磷酸氢钙、碳酸钙等其他辅助原料,钙磷比均为1.50,制备了2种类型的骨水泥。对固化骨水泥样品进行了Ringer's模拟液浸泡实验。测定浸泡液pH值、样品的抗压强度和样品的断面显微形貌随浸泡时间的变化。结果表明:2种骨水泥的凝结时间基本相同,初凝时间为5min左右,终凝时间为19.5min;但两者浸泡液的pH值变化和抗压强度等性能有较大的差别,以α 磷酸三钙为主要原料的骨水泥的主要性能明显优于以磷酸四钙为主要原料的骨水泥。     

碳纤维增强磷酸钙骨水泥

以碳纤维为增强相,Na2HPO4/柠檬酸为调和液,α-磷酸三钙、磷酸四钙、磷酸二氢钙、羟基磷灰石和碳酸钙为原料制备骨水泥,研究不同掺杂比例的短碳纤维对其性能的影响。在磷酸钙骨水泥中掺杂碳纤维能够提高样品的致密性,缩短固化时间,提高抗压强度。当掺杂质量分数0.5%的碳纤维时,骨水泥的初凝、终凝时间分别为9.3和24.9min,模拟体液中浸泡28d后抗压强度最大为38.24MPa。掺杂的碳纤维对浸泡液pH影响不大,pH在小范围内浮动,均在人体安全范围内。     

Preparation of a Novel Calcium Phosphate Cement Using N-methylene Phosphonic Chitosan as a Gelling Agent

1Introduction Self hardeningcalciumphosphatecements(CPC)consistingoftetracalciumphosphate(TTCP)anddicalci umphosphate(DCPAorDCPD)havebeendeveloped since1986.ThereactionbetweenDCPAandTTCPis[1]:2CaHPO4 2Ca4(PO4)2OH2OCa10(PO4)6(OH)2.CPC isreadilyosseointegra…     

Microstructure and mechanical properties of calcium phosphate cement/gelatine composite scaffold with oriented pore structure for bone tissue engineering

The macroporous calcium phosphate(CPC) cement with oriented pore structure was prepared by freeze casting. SEM observation showed that the macropores in the porous calcium phosphate cement were interconnected aligned along the ice growth direction. The porosity of the as-prepared porous CPC was measured to be 87.6% by Archimede’s principle. XRD patterns of specimens showed that poorly crystallized hydroxyapatite was the main phase present in the hydrated porous calcium phosphate cement. To improve the mechanical properties of the CPC scaffold, the 15% gelatine solution was infiltrated into the pores under vacuum and then the samples were freeze dried to form the CPC/gelatine composite scaffolds. After reinforced with gelatine, the compressive strength of CPC/gelatine composite increased to 5.12 MPa, around fifty times greater than that of the unreinforced macroporous CPC scaffold, which was only 0.1 MPa. And the toughness of the scaffold has been greatly improved via the gelatine reinforcement with a much greater fracture strain. SEM examination of the specimens indicated good bonding between the cement and gelatine. Participating the external load by the deformable gelatine, patching the defects of the CPC pores wall, and crack deflection were supposed to be the reinforcement mechanisms. In conclusion, the calcium phosphate cement/gelatine composite with oriented pore structure prepared in this work might be a potential scaffold for bone tissue engineering.     

Preparation and Compressive Strength of Calcium Phosphate Bone Cement Containing N,O-carboxymethyl Chitosan

1Introduction Calciumphosphatebonecement(CPC)hasbeen preparedbyBrownandChowin1985[1].Thematerial consistsofcementpowderandbuffersolution.Thepow dercontainsteracalciumphosphate(TetCP)anddicalci umphosphate(DCPA).Thebuffersolutionismadeupof phosphateandwate…     

粉煤灰掺量对磷酸镁水泥基复合材料力学性能影响

研究了粉煤灰掺量对磷酸镁水泥基材料的抗压强度、抗折强度、耐磨性和膨胀性能的影响。实验结果表明,随着粉煤灰掺量的增加,磷酸镁水泥净浆的抗压强度先增大后下降,粉煤灰掺量为胶凝材料质量的10%时,抗压强度最大;而材料的抗折强度和耐磨性能随着粉煤灰掺量的增加而下降。其膨     

熟料粒度对骨粉/磷酸钙生物骨水泥结构与性能的影响

采用新方法首次将动物骨中的鱼骨引入到磷酸三钙和磷酸氢钙等原料体系中通过高温烧结制备磷酸钙基生物骨水泥（CPC）,以柠檬酸和柠檬酸钠的缓冲液为固化液、按一定的液固比制备固化试样,通过扫描电子显微分析（SEM）和力学性能测试等方法,研究了熟料粒度对其固化试样结构与抗压强度的影响.结果表明：制备过程中骨水泥粉末的粒度对其固化试样的微观结构及其抗压强度有着较为显著的影响,通过调整骨水泥粉末的粒度可达到优化其固化试样的微观结构和改善其力学性能的目的.     

Preparation, Fundamental Characteristics and Biosafety Evalution of Compound rhBMP-2/CPC

1Introduction Calciumphosphatecement(CPC)isanewtypeof bonesubstituteinrecentyearswithagoodboneconduc tion,absorbability,biologicalcompatibilityandetc.The mechanicalfixationcangraduallyturnintobiologicalfixa tioninitsanaphase[1].Atthesametime,calciumphos phatecementhasbeenprovedtobeagoodcarrierofthe bonemorphogeneticprotein(BMP)[2],whichcanover cometheshortagesthatsimplexBMPwillbedilutedby enchymaanddecomposedbyproteaseafteritsimplanta tionintothehumanbody,anditseffectiveconcentration insom…     

Biological Evaluation of α—TCP／TTCP Composite Bone Cement

α-tricalcium phosphate(α-TCP)/tetracalcium phosphate(TTCP) composite bone cement had good hydration characterstic.In our system,α-TCP/TTCP powder mixture was mixed with water at a powder/liquid(P/L) ratio of 1.50g.mL^-1.The setting time could be adjusted.the maximum compressive strength was 45.36MPa,and the hydration product was hydroxyapatite(HAP),In vitro biological simulated experiments indicate that α-TCP/TTCP bone cement has α certain dissolubility.The hardened product is mainly HAP after soaking in simulated body fluid(SBF) for 10 weeks.The results of in vitro test and animal experiments and SEM analyses show that no local or general toxicity response,no muscle stimulation,no haemolysis,no cruor,no inflammatory reaction and no exclusion response are caused by α-TCP/TTCP cement,which can be contributed to bone tissue spreading and impinging,α-TCP/TTCP cement hydrated and hardened continually in vivo.The materials fused with host bone together with implanting time prolonging.Therefore,it is beliened that α-TCP/TTCP composite bone cement has a high biocompatibility and bioactivity,a certain biodegradation and good osteogenesis as well.     

Influence of Calcium Sulfate State and Fineness of Cement on Hydration of Portland Cements Using Electrical Measurement

1 IntroductionThe calcium sulfate state includes gypsum, hemi-hydrate and anhydrite .Inthe modern Portland cement in-dustry,the gypsumis used as a setting retarder for reac-tion with C3A[1]. With the presence of gypsumin theformof CaSO4·2H2O,the gypsum dissolves and reactsprimarily with C3A and C4AF to form ettringite . Thisettringite isinitiallyformed with a veryfine-needle crystalstructure ,whichforms a diffusion barrier onthe surface ofthe cement . This coating avoids the unwanted fl…     

Augmentation of pedicle screw fixation with calcium phosphate cement

To determine whether a biodegradable calcium phosphate cement (CPC) provides significant augmentation of pedide screw fixation or not, an in vitro biomechanical study was carried out to evalwate the biomechanical effea of CPC in the restoration and angmentation of pedide screw.fixation. Axial pullout and cyclic beruding resistance test were employed in the experiment, and polymethylmethacrylate (PMMA) was chosen as control. The results demonstrate that the pullout strengths following CPC restoration and augmentation are 74% greater on an average than those of the control group, but less than those of PMMA restoration group ard aygmentation group respectively ( increased by 126% versus control). In cyclic bending resistance test, the CPC augmented screws are found to withstand a greater number of cycles or greater loading with less displacement before loosening,but the augmentation effect of PMMA is greater than that of CPC.     

Tribological Properties of PVA-H Composites Reinforced by Nano-HA Particles

The friction and wear behaviors of tribological mechanical components were studied on a four-ball tester under dry conditions, and the wear mechanism was analyzed by observed worn surface using a scanning electron microscope （SEM）. It was found that the friction and wear properties were improved by the addition ofnano HA particles. The composite containing 1 wt% nano HA had the optimum friction coefficient. It is also found that the addition of nano HA increases the wear resistance of oure PVA-H and PVA-H composites.     

Solid State Reaction Synthesis and Thermoelectric Properties of Mg2Si doped with Sb and Te

Doped with Sb and Te, Mg₂ Si based compounds were prepared respectively by solid state reaction at 823K for 8h. Effects of dopants of Sb and Te on the structure and thermoelectric properties of the compounds were investigated. By calculating the values of the electrical conductivity for Sb-doped sample, the mechanism of electric conduction at 625 K is different. The figure of merit for sample doped with 0.4wt% Te at 500K is 2.4×10⁻³W/mK², and it reaches 3.3×10⁻³ W/mK² at 650K for the sample doped with 0.5wt% Sb. The values are more than 1.4 times and 2.3 times of the pure Mg₂Si sample. JIANG Hong-yi : Born in 1961     

Porosity and pore size distribution measurement of cement/carbon nanofiber composites by 1H low field nuclear magnetic resonance

The dispersion effect of carbon nanofibers （CNFs） in aqueous solution and the mechanical properties, porosity, pore size distribution and microstructure of CNFs reinforced cement-based composites were investigated in this paper. To achieve effective dispersion of CNFs, a method utilizing ultrasonic processing and a commercially surfactant were employed. CNFs were incorporated to cementitious materials with the addition of 0.1 wt% and 0.2 wt% of cement with a water/cement ratio of 0.35. The mechanical properties of CNFs/ cement composites were analyzed, the porosity and pore size distribution were characterized by ^1H low field nuclear magnetic resonance （NMR）, and the microstructure was observed by scanning electron microscopy （SEM）. The results indicate that the optimum concentration ratio of MC to CNFs is 2：1 for dispersing in aqueous solution. Moreover, in the field of mechanical properties, CNFs can improve the flexural strength and compressive strength. The increased mechanical properties and the decreased porosity of the matrices correspond to the increasing CNFs content and CNFs act as bridges and networks across cracks and voids.     

Preparation of new tissue engineering bone-CPC/PLGA composite and its application in animal bone defects

To investigate the feasibility of implanting the biocomposite of calcium phosphate cement (CPC)/polylactic acid-polyglycolic acid (PLGA) into animals for bone defects repairing, the biocomposite of CPC/PLGA was prepared and its setting time, compressive strength, elastic modulus, pH values, phase composition of the samples, degradability and biocompatibility in vitro were tested. The above-mentioned composite implanted with bone marrow stromal cells was used to repair defects of the radius in rabbits. Osteogenesis was histomorphologically observed by using an electron-microscope. The results show that compared with the CPC, the physical and chemical properties of CPC/PLGA composite have some differences in which CPC/PLGA composite has better biological properties. The CPC/PLGA composite combined with seed cells is superior to the control in terms of the amount of new bones formed after CPC/PLGA composite is implanted into the rabbits, as well as the speed of repairing bone defects. The results suggest that the constructed CPC/PLGA composite basically meets the requirements of tissue engineering scaffold materials and that the CPC/PLGA composite implanted with bone marrow stromal cells may be a new artificial bone material for repairing bone defects because it can promote the growth of bone tissues.     

Strength and chloride resistance of blended Portland cement mortar containing palm oil fuel ash and fly ash

This paper presented a study on the strength and chloride resistance of mortars made with ternary blends of ordinary Portland cement (OPC), ground palm oil fuel ash (POA), and classified fly ash (FA). The mortar mixtures were made with Portland cement type I containing 0-40wt% FA and POA. FA and POA with 1wt%-3wt% retained on a sieve No.325 were used. The compressive strength and rapid chloride penetration depth of mortars were determined. The results reveal that the use of ternary blended cements produces ...     

高游离氧化钙水泥的显微结构与膨胀机理研究

运用扫描电子显微镜（SEM）研究了高游离氧化钙（f-CaO）水泥的 经及其在水泥石中氢氧化钙的分布和显微结构特征。讨论了水化早期和后期Ca(OH）2晶体的结晶特性及界面结合关系,指出了熟料中成大堆分布的f－CaO晶体缓慢水化导致Ca（OH）2晶体不断长大是造成水泥安定性不合格的主要原因。     

Strength development and microstructure of hardened cement paste blended with red mud

Red mud was activated to be a mineral admixture for Portland cement by means of heating at different elevated temperatures from 400 °C to 700 °C. Results show that heating was effective, among which thermal activation of red mud at 600 °C was most effective. Chemical analysis suggested that cement added with 600 °C thermally activated red mud yielded more calcium ion during the early stage of hydration and less at later stage in liquid phase of cement water suspension system, more combined water and less calcium hydroxide in its hardened cement paste. MIP measurement and SEM observation proved that the hardened cement paste had a similar total porosity and a less portion of large size pores hence a denser microstructure compared with that added with original red mud. Funded by the National 973 Program of China (No. 2001CB610703)     

Tribological Properties of Polyvinyl Mcohol Hydrogel Reinforced with Nanometer Hydroxy Apatite

As a potential artificial cartilage material,the friction and wear properties of nano-hydroxy apatite(HA)particles filled poly(vinyl alcohol)hydrogel(PVA-H)composites sliding against stainless steel disk under water lubrication condition were studied by using a four ball tester.The worn surfaces were investigated by using a scanning electron microscope(SEM)to determine the wear mechanisms.Experimental results show that filling HA to PVA-H will slightly increase the friction coefficient of composites with the increasing of HA content under water lubrication condition.Meanwhile,HA particles can greatly reduce the wear mass loss of the PVA-H composites and enhance the load carrying capacity,the wear loss of the 1 wt% HA reinforced PVA-H composites can be decreased by 30 percent under 2.0 MPa to 50 percent under 0.5 MPa contact pressure.We also found that 2 wt% HA content of composites increase the wear mass loss under the same condition.SEM examination shows that the worn surface of low HA containing(1 wt%)composites are much smoother than that of pure PVA-H or high HA containing(2 wt%)composites under 1.5 MPa contact pressure.It is also found that there are big hole and big reunited HA particles in the surface of 2 wt% HA containing composites,which leads to deterioration of the surface of samples under higher loads in water lubrication.These results may be useful in the tribological design of artificial articular cartilage material.