Synthesis of novel Meerschaum (Sepiolite) derived bioceramics versus hydroxyapatite based bone grafts

Meerschaum Sepiolite derived bioceramics have been synthesised via the sol–gel method and were compared with nano (N) and micro (M) scale-hydroxyapatite (HA) based bone grafts. The newly fabricated Meerschaum (Sepiolite) bioceramic bone grafts were characterised by Scanning Electron Microscopy (SEM), Fourier Transform Infrared Spectroscopy (FTIR) and X-ray Diffraction (XRD). The mechanical properties were determined through the Compression and Vickers hardness tests. Significant differences were observed in the FTIR spectrography of the samples as Meerschaum (Sepiolite) addition increased in HA-based biografts. In the nano-scale-HA-based biografts and increase in Sepiolite ratio increased the porosity, In the micro-scale-HA based biografts, porosity decreased with increased Sepiolite ratio. However, compression strength was not found to deteriorate with Sepiolite additions. Overall, the results confirm the suitability of such graft materials for biomedical applications.     

泛文化现象盛行背景下的园林文化诉求——第八届中国(重庆)国际园林花卉博览会安阳园设计

安阳展园位于第八届重庆园博会南部大中华展区的北方园林展园中,占地面积为2900 m2。在对当今泛文化现象盛行进行反思后,展园设计择取安阳当地历史悠久的"甲骨文字"为主题,以自然原型为基础筛选造园要素,借鉴"安阳园"三个字的甲骨文书法形体组合形成布局结构。设计以水为脉,串连起各个园林要素来强化布局,把平面的文字形象转化为有致的立体化园林空间。     

Verbundverhalten von Vollgewindeschrauben in Brettschichtholzbauteilen

Bond behaviour of self‐tapping screws being used as reinforcement in glue‐laminated timber elements – Part 2: Analytical and numerical investigations as well bond model derivation for the calculation of anchorage length In favor of the investigation of bond behaviour, force transfer and anchorage length of self‐tapping screws, several tests have been realized at the Chair of Structures and Structural Design in cooperation with the Institute for Building Material Research of the RWTH Aachen University. The experimental investigations comprise more than 160 pull‐out tests of screws with long embedment length and over 84 load distributions tests. Additionally, several tests displaying the effect of longitudinal cracks in the surrounding wood as well as the effect of the screw tip have been conducted. Through various analyses of the bond behaviour, the experimental investigations form the basis for the calibration and evaluation of the numerical models and allow a prediction of the force transfer of the screws in glue‐laminated elements. Design rules that enable the application of the self‐tapping screws as reinforcement in timber elements have been derived from the knowledge obtained in the experimental and numerical investigations. This paper, which results from a research project funded by the German Research Foundation [1], presents the results of investigations on the bond behavior of self‐tapping screws in glue‐laminated timber elements. Part 1 elaborates on the experimental investigations [2] whereas part 2 illustrates the numerical analyses and presents a bond model, which enables the design of the anchorage length and the safe application of the screws as reinforcement in timber elements.     

戊二醛接枝共聚改性骨胶粘合剂的研究

以戊二醛作为接枝改性剂制备改性骨胶粘合剂。研究了醛胶比、接枝温度和接枝时间等对改性骨胶粘合剂性能的影响,并采用红外光谱(FT-IR)和热失重分析(TGA)法对产物的结构与热稳定性进行了表征。结果表明:当醛胶比为0.2∶100、接枝温度为30℃和接枝时间为60 min时,所得改性骨胶粘合剂的剪切强度为10.7 MPa、凝胶温度为-2℃;此时产物的接枝效果明显,并具有良好的热稳定性能。     

转化生长因子-β在骨髓间充质干细胞治疗实验性自身免疫性重症肌无力机制中的作用

目的探讨转化生长因子-β(TGF-β)在骨髓间充质干细胞(BMSCs)治疗实验性自身免疫性重症肌无力(EAMG)机制中的作用。方法分离培养健康Lewis大鼠BMSCs,并进行大量体外扩增;以大鼠来源的乙酰胆碱受体(R-AChR)2次免疫Lewis大鼠,建立EAMG模型;第2次免疫的同时,经尾静脉移植BMSCs,1×107个/只,依据Lennon评分标准,进行体重测量和临床体征评定。并通过体外实验进一步探讨TGF-β在治疗EAMG过程中的具体机制。结果BMSCs移植明显缓解了EAMG的临床症状,临床评分及体重变化差异均有统计学意义,表明治疗有效;体外实验结果显示,BMSCs能通过TGF-β的分泌影响AChR特异性Th17/Treg细胞亚群的分布及其相关因子的分泌,以anti-TGF-β抗体封闭后,这种调节作用在一定程度上被抑制。结论BMSCs通过细胞因子TGF-β,能在一定程度上调节AChR特异性Th17/Treg细胞亚群的平衡,从而起到治疗EAMG的作用。     

骨髓间充质干细胞向视网膜神经节样细胞的分化

目的探讨乳鼠视网膜细胞条件分化液诱导骨髓间充质干细胞(BMSCs)的神经分化情况,以期为视网膜退行性疾病提供治疗方案。方法体外分离培养Wistar大鼠乳鼠BMSCs,观察BMSCs的增殖情况并进行鉴定;制备乳鼠视网膜细胞条件分化液,以其诱导BMSCs,观察BMSCs的神经分化情况,并行免疫组化鉴定。结果体外培养获得了较纯的BMSCs;在乳鼠视网膜细胞条件分化液的环境中,诱导后72h,BMSCs胞体收缩成锥形或球形,细胞突起变细、变长,呈神经细胞的典型形态;免疫组化结果显示,部分细胞呈神经元特异性烯醇化酶(NSE)、巢蛋白(nestin)和Thy1.1阳性反应。结论乳鼠视网膜细胞条件分化液可诱导BMSCs分化成视网膜神经节样细胞。     

浅谈建筑改造与加固（植筋及粘钢）施工

介绍了建筑结构改造加固施工工艺流程及其施工技术,并对该工艺的特点、工艺流程、质量检查要求及冬季施工的监控等方面进行了分析,以完善结构改造加固施工工艺,从而促进建筑改造加固工艺的发展。     

Osteosclerosis due to endemic fluorosis

Endemic water borne fluorosis is a public health problem in Isparta, a city located in southern Turkey. In order to investigate the association between osteosclerosis and fluorosis, we retrospectively screened the results of lumbar spine and femur neck bone mineral density (BMD) of 1500 patients who were examined before, for any reason in between 2001-2003. Sixty nine patients (67 females and 2 males, mean age 52.6+/-10.2) with vertebra T-scores>or=+2 were found only except a patient with osteoid osteoma in the femur neck (femur T-score+6.64). Thirty-four of the patients could be reexamined with lateral vertebra BMD and investigated for fluorosis and the other etiologic causes of osteosclerosis. Of 34 patients, 14 had either mottled tooth enamel or urine fluoride level greater than 1.5 mg/l. Other etiologic causes were hypothyroidism (2), hypoparathyroidism (1), history of lumbar fracture (1), use of retinoids (1), vitamin D (7), oral calcium preparations (9), and bisphosphanates (3). Lateral lumbar vertebral T-score was greater than+2 in 12 patients (35.3%). Femur T-score was greater than+2 in 7 patients (20.6%). Fourteen patients (41.2%) had lateral vertebral or femur T-score>or=+2. Five (35.7%) of these patients had signs of fluorosis, as discussed before. Mean body mass index of individuals with fluorosis was 36.4+/-7.9 and this result was significantly higher than other osteosclerotic subjects (31.6+/-4.4). In conclusion we believe that approximately one third of the osteosclerosis in our region was due to endemic skeletal fluorosis and obesity may enhance this osteosclerotic type bone changes in endemic fluorosis.     

Preparation and characterization of zinc modified calcium silicate/polycaprolactone with graphene oxide composite coating for bone repair applications

The goal of biomaterial interest is the ease of the bone tissue regeneration process or the replacement of damaged bone and other tissues with recently generated bone tissue. Calcium silicate (CaSi) bioceramic is a vital material for bone tissue engineering, predominantly for bone repair. Though, the low toughness of calcium silicate imitates its load-bearing applications. The electrophoretic deposition technique was used to coat various concentrations of Zn²⁺ substituted CaSi on TNT. In this work, a novel as-obtained an appropriate orthopedic implant hybrid material by charged calcium ions of mineralized calcium silicate united with PCL-negatively charged graphene oxide [Zn-CaSi (S₁-S₃)/PCL (P₁-P₃)/GO]. Hence, the effectively as-obtained [Zn-CaSi (S₁-S₃)/PCL (P₁-P₃)/GO] bone-like apatite on the ternary composite coatings on the surface was proven via XRD, FT-IR, FESEM with EDAX spectra, HR-TEM and BET analyses etc., Moreover, the TNT/S₂/P₂@GO ternary composite coatings exhibit better mechanical properties and antibacterial activity. The metal ions released from the coatings were calculated via ICP-AES studies. Moreover, the cell viability and also the live/dead staining of MG63 human osteoblasts cells on the subsequent composite coating material for better cell growth in orthopedic applications.     

Physicochemical and biological properties of composite bone cement based on octacalcium phosphate and tricalcium silicate

Biocompatible tricalcium silicate (C₃S) bone cement is widely used as dental and bone repair material; however, its long setting time, poor injectability and low initial mechanical properties limit clinical applications. In order to improve C₃S silicate bone cement and its derivatives to play a more important role in tooth restoration, bone defect repair, implant coating and tissue engineering scaffolds, a novel C₃S and octacalcium phosphate (OCP) composite bone cement (OCP/C₃S) was prepared and evaluated for setting time, injectability, anti-flocculation, pH, microstructure, bioactivity and cytotoxicity. The setting time of the OCP/C₃S composite bone cement was controlled within the clinically operable time range (8.3–13.7 min); the cement exhibited good compressive strength, injectability (93.54%), and anti-collapse performance. The 20% OCP/C₃S composite bone cement had a compressive strength of 28.94 MPa, 93% stronger than pure C₃S (14.98 MPa). An in vitro immersion test showed that the composite bone cement had excellent hydroxyapatite forming ability, proper degradation rate, and a low pH value. Cellular experiments confirmed the low cytotoxicity of the composite bone cement and its great capacity for cell proliferation. These results indicate that 20% OCP/C₃S composite bone cement is a promising biomaterial.