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.     

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。     

Osteogenesis Capacity of a Novel BMP／a-TCP Bioactive Composite Bone Cement

To improve the osteogenesis ability of α-trkalcium phosphate (a-TCP ) bone cement, a novel BMP/ a- TCP composite bone cement was prepared. By measuring the setting time and compressive strength, the hydration characteristic of bone cemtwnt icts eralnated. Animal experiments including histological observation, radiographic investigation as well as digital image analyses reveal the difference of osteogenesis ability among BMP, a TCP bone cetnent and BMPI a-TCP composite bone cement, Results show that a-TCP bone cement possesses excellent hydration and setting properties as well as high mechanical property, Comparison experiments show that BMPI a-TCP composite bonc cement has a stronger osteogenesis obility. The gross observation of the implant site does not exhibit any inflammation or necrosis. Histohwcal analyses reveal that the material has good osteointegration with host bone, and new bone formntion is detected within the materials, which are degrading. Strong osteogenesis ability of the composite is due to not only the excellent osteoconductive potential but also the osteoinductive potential contributed by attire BMP releasing and the material degradation . Large skull defect could be well-healed ty filling BMPl a-TCP composite bone cement. This novel material proves itself to be an absorbable and bioaetive bonecement with an osteogenesi ability.     

聚合磷酸钙骨水泥的制备和性能研究

采用丙烯酸和衣康酸的共聚物与自制磷酸钙粉末反应制备骨水泥。用自凝牙托水对类磷酸四钙（TTCP）粉末进行表面改性后所制备的骨水泥,初凝时间为4．5min,终凝时间为8.5min,抗压强度可达４２MPa。采用类TTCPα－磷酸三钙的混合粉料制备的骨水泥,初凝时间为５．５min,终凝时间为１１．０min,抗压强度可达４３MPa。     

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。     

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 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…     

Effect of substitutional Sr ion on mechanical properties of calcium phosphate bone cement

A novel calcium phosphate cement was developed by adding different amount of SrO to tetracalcium phosphate during the fabrication process. The experimental results show that compressive strength of cements based on tetracalcium phosphate doped with SrO significantly increases with the increase of SrO content, approximately 60 MPa, whilst the mechanical behavior of CPC slightly decreases if 0.7wt% SrO is added. X-ray diffraction measurement confirms the setting reaction of doped cements is similar to that of pure calcium phosphate cement (CPC). Low crystalline hydroxyapatite (HA) is found to be the main constituent of set cement. A mechanical reinforcement effect is resulted from the substitution of Sr ion to Ca²⁺ in tetracalcium phosphate (TTCP), accelerating HA crystal formation and a more cross-linked cement structure. In vitro bioactivity tests showed that CPC added with 0.5wt% SrO had a more rapid degradation compared with pure CPC.     

水玻璃激发碱-矿渣水泥的水化放热和凝结性能

水玻璃模数和碱当量对碱-矿渣水泥的水化放热和凝结性能有重要影响。该文系统地探讨了水玻璃模数和碱当量对碱-矿渣水泥水化放热和浆体凝结时间及抗压强度的影响规律。结果表明：随模数的增加,水化热降低,凝结时间延长,抗压强度先增加,随后降低;随碱当量的增加,水化热增加,凝结时间稍有延长,强度增加。比较合理的水玻璃模数Ms在1.0~2.0,碱当量为矿渣质量的3%~6%。     

水泥-粉煤灰复合胶凝体系的早期水化性能

为了研究粉煤灰掺量和温度对水泥水化的影响,测试了粉煤灰掺量0～60%的水泥-粉煤灰水化体系,在温度20、24和28 ℃下的凝结时间及2d内的电阻率发展及抗压强度,发现凝结时间与电阻率发展速率曲线的第一峰值点对应时间遵循线性关系. 在同一温度下,2d的抗压强度和电阻率值显示出良好的正相关线性关系——温度越高,斜率越小,表明电阻率比强度对温度变化更加敏感. 扫描电镜结果论证了粉煤灰在2d内尚未参与水化反应,主要起填充和稀释作用. 因此,可借助电测法估算和预测变温条件下水泥-粉煤灰水化体系的抗压强度及凝结时间.     

AW玻璃基骨水泥的制备及其结构性能表征

以AW生物玻璃与柠檬酸/磷酸氢钾复合固化液混合制得玻璃基生物骨水泥(GBC),利用XRD、FTIR和SEM对GBC的产物晶相、化学组成和显微结构进行了分析,并对其力学性能进行了测试。结果表明,GBC在固化反应后就已经有羟基磷灰石(HA)晶相生成;随着GBC在SBF中浸泡时间的延长,又生成了少量碳酸钙晶体,且HA晶相数量增多,抗压强度在7 d时达到最大值,骨水泥呈现多孔结构。     

多元复合超早强灌浆料试验

目的研究铝酸盐水泥、普通硅酸盐水泥、石膏和硅灰四元复合体系超早强灌浆料的流动度、凝结时间和力学性能,找出超早强灌浆料的最佳配比．方法采用行星式搅拌机将原材料搅拌均匀,利用跳桌测试流动度,贯入阻力法测定凝结时间,水泥压力试验机测试力学强度,混凝土收缩膨胀仪测试膨胀性能,分析砂胶比为1．0的微观结构．结果该体系辅以多种外加剂,采用高胶砂比可以保证初始流动度大于325mm,30min流动度大于280mm,2h抗压强度达34．80MPa,24h抗折达13．82MPa,28d抗压强度大于99．90MPa,56d抗压强度大于28d抗压强度．早期SEM微观结构显示晶形生长良好,结构致密．结论铝酸盐水泥、普通硅酸盐水泥、石膏和硅灰按一定的比例复配,具有良好的施工和易性和力学性能．     

盾构隧道同步注浆浆液配合比优化设计

盾构法施工过程中,盾尾同步注浆对控制隧道轴线上浮和地面沉降起着至关重要的作用.为使盾构隧道同步注浆浆液具有较好的工作性能,选用水泥、粉煤灰、膨润土、砂、水作为原材料,采用正交设计的方法进行试验,探讨了浆液各原材料对浆液稠度、凝结时间、泌水率、7d抗强度等指标的影响规律及同步注浆浆液配比的优化方向.试验表明:水泥是影响凝结时间和抗压强度的主要因素,水泥的加入能够缩短凝结时间、增大抗压强度和降低泌水率;粉煤灰能改善浆液和易性;膨润土有增稠、保水的作用,能提高浆液稳定性,但掺量要控制在一定范围内;砂作为浆液骨料起填充作用,主要影响浆液稠度,砂的用量与浆液稠度大小呈反比趋势;水是影响泌水率的主要因素,用水量增加导致浆液泌水率、稠度增大,凝结时间变长.最优的配合比为:水泥∶粉煤灰∶膨润土∶砂∶水为160∶400∶50∶830∶360,制备的浆液稠度为11~12cm,凝结时间为10~13h,泌水率不高于3%,7d抗压强度不低于2MPa.     

Experimental research on inorganic solidified foam for sealing air leakage in coal mines

In order to efficiently seal air leakages and control spontaneous combustion of coal, solidified foam was developed by adding a certain compound additive to fly coal ash and cement as the main materials. It was prepared basing on the foaming characteristic through physical and mechanical system. We studied the effects of the different types of foaming agents, the mass ratio of cement to fly ash, and the mass ratio of solid to water and content of cellulose on the performance of solidified foam. The results show that when adding the composite protein, surfactant and cellulose foaming agents. The cement-fly ash ratio of 0.75:1, the water solid ratio as large as 2:1, and the solidified foam with high properties and density of only 516 kg/m³ and compressive strength of up to 12.68 MPa were prepared. But the initial setting time, identity and compressive strength may be changed by varying the water solid ratio and/or the additives. We theoretically analyzed the influence mechanism of foam density, compressive strength and water solid ratio. The solidified foam is especially suitable for sealing surface leakage channels and filling the goaf with a wide application prospects.     

矿粉对水泥和混凝土性能的影响

为了探寻矿粉细度及掺入量对水泥和混凝土性能的影响,通过试验测试方法,分析了矿粉和水泥的基本性质,研究了超细矿粉和普通矿粉的掺量对水泥基材料标准稠度、凝结时间、流动度和力学性能的影响.结果表明：普通矿粉使水泥净浆标准稠度需水量下降,而超细矿粉则增加标准稠度需水量,两种矿粉都使水泥净浆凝结时间略微延长.普通矿粉可以改善水泥净浆的流动度,超细矿粉的加入则降低了水泥净浆的流动度.普通矿粉和超细矿粉降低水泥净浆早期（7 d）抗压强度,提高后期（28 d）抗压强度,掺10％～50％的普通矿粉的水泥净浆28 d抗压强度提高2.9％～9.7％,掺入超细矿粉28 d抗压强度提高3.9％～20.1％,普通矿粉和超细矿粉的最佳掺量为10％～30％;两种矿粉替代10％～50％水泥所配制的混凝土的强度得到了明显的提高.     

石灰石粉细度对水泥混凝土性能的影响研究

通过对比试验研究了不同细度的石灰石粉对水泥混凝土性能的影响。结果表明,磨细石灰石粉减少了水泥的标准稠度用水量,但效果甚微,缩短了水泥的初、终凝时间;并且使混凝土拌合物的塌落度增大,提高了拌合物的流动性和可塑性;通过对不同龄期混凝土试块抗压强度的测定表明,磨细石灰石粉提高了混凝土的抗压强度,并且随着石灰石粉细度的增加,混凝土的抗压强度增大。     

早强剂复配和砂的级配对超早强灌浆料性能影响

目的探讨硫酸钠、三乙醇胺和早强组分A复合对超早强灌浆料终凝时间、抗折强度和抗压强度等性能与结构的影响.为实际工程中的应用提供理论依据.方法对石英砂的级配进行了较系统的研究.采用行星式搅拌机将原材料搅拌均匀,用贯入阻力法测定凝结时间,用水泥压力试验机测试力学强度,用电子显微镜分析砂胶比1.0的微观结构.结果单掺0.05%三乙醇胺,0.8%硫酸钠或0.1%早强组分A,超早强灌浆料的各项指标基本满足要求.将硫酸钠、三乙醇胺和早强组分A按合理比例复合;石英砂的最佳质量级配为5∶5∶2,且砂率范围1.0~1.5;超早强灌浆料的终凝时间为50~60 min,初始流动度大于320 mm,0.5 h流动度大于280 mm,2 h抗压强度达35.6 MPa,1 d抗折大于12 MPa,28 d抗压强度大于90 MPa.结论采用砂的最佳级配,将硫酸钠、三乙醇胺和早强组分A复合掺入后,胶凝材料的水化早期的水化程度的增幅最大,后期保持稳定增长.提出复合早强剂最佳配比和砂的最佳级配.     

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.     

AW玻璃基骨水泥的制备及其结构性能表征

以AW生物玻璃与柠檬酸／磷酸氢钾复合固化液混合制得玻璃基生物骨水泥（GBC）,利用XRD、FTIR和SEM对GBC的产物晶相、化学组成和显微结构进行了分析,并对其力学性能进行了测试。结果表明,GBC在固化反应后就已经有羟基磷灰石（HA）晶相生成;随着GBC在SBF中浸泡时间的延长,又生成了少量碳酸钙晶体,且HA晶相数量增多,抗压强度在7d时达到最大值,骨水泥呈现多孔结构。     

矿渣粉的活性和流动度研究

对6个细度水平的矿渣粉活性和流动度研究，矿渣粉的抗折活性指数比抗压活性指数高．它在28d内是龄期和细度的单调增函数．矿渣粉的抗压活性指数在7d内是龄期和细度的单调增函数．28d的抗压活性指数采用不同品质的硅酸盐水泥表现存在差异．矿渣粉比表面积在350-650m^2／kg范围内．流动度比都大于110．而矿渣水泥的标准稠度用水量却比硅酸盐水泥高．采用不同细度硅酸盐水泥作为对比样时，矿渣粉流动度比偏差在14％以内．