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1.5-mm thick Al–Mg-Li alloy plates were successfully lap welded using refill friction stir spot welding (RFSSW), and the microstructure and mechanical properties of the joints were investigated. The results show that dynamic recrystallization (DRX) has occurred in the stir zone (SZ) of the joint, forming fine equiaxed grains with an average size of 10 μm. There is a strong texture in the base material, while no obvious texture in the SZ. The void defect at the horizontal surface and the lack of mixing defect at the vertical interface are the most important factor influencing the lap shear strength and the cross tension strength, respectively. The maximum lap shear strength is 6.2 kN, and the maximum cross tension strength is 2.7 kN. In addition, there are three fracture modes that can be observed after the tensile-shear tests, i.e., parent sheet fracture, plug type fracture, and interface fracture, while only plug type fracture mode presents after the cross tension tests.

Non-enzymatic glycosylation reaction, which proceeded at an accelerated rate in diabetes, directly caused sharp diminution of total haemoglobin due to glycosylated proteins including haemoglobin digested by macrophages. The diminution contributed to hypoxia of tissue that repressed the enzymatic activities in the respiratory chain as well as in the tri-carboxylic acid cycle (TCA) and Embden-Meyerhof-Parnas (EMP) pathways. It was postulated that non-enzymatic glycosylation reaction accelerated the rise of blood glucose. The theory was further proven by the hypoglycaemic activities of the extract from Tremella aurantialba broth (TBE). TBE inhibited the formation of advanced glycosylation end-products (AGEs) in vitro (IC50 =1.7 mg/ml) and in vivo. TBE, when given in vitro, increased the concentration of total haemoglobin and supply of oxygen, enhanced respiration of tissue, decreased the levels of NADH, speeded up catabolism of glucose and finally generated significant anti-hyperglycaemic and hypoglycaemic effect on alloxan-induced diabetic rats. In addition it elevated plasma insulin level. Oral administration of TBE (100 mg/Kg bw) once a day for 4 weeks resulted in significant reduction in the plasma levels of glucose, fructosamine and the ratio of glycosylated haemoglobin to total haemoglobin. Moreover, oral administration of TBE increased the total haemoglobin and plasma insulin levels and enhanced some key enzymatic activities of EMP, TCA pathways and respiratory chain in the blood of diabetic rats compared with control. (Int J Diabetes Metab 15: 52-59, 2007)

Abstract Triple shape memory polymers (TSMPs) can be programed to remember and switch between three distinct shapes with the use of external stimuli, typically an increase in temperature. In this work, constitutive equations have been developed to model the thermo-mechanical behavior of crystallizable TSMPs. In these materials the transient shapes are fixed by the formation of crystalline phases, whereas the switching between the temporary and permanent shapes is due to the melting of the crystalline phases. The model is developed using a framework based on the theory of multiple natural configurations. Constitutive equations have been formulated for the original amorphous phase, the intermediate semi-crystalline phases, and transition of the crystalline phases, during the shape fixation and recovery cycles of TSMPs. These models have been developed within a full thermodynamic framework, extending our previous work in which the models were developed within a mechanical setting (Moon, Cui, & Rao, 2015; Moon, Rao, & Chester, 2016). The model has been applied to solve for the problems of inflation and extension of a hollow cylinder and uniaxial extension. The results are consistent with experimental observations. [ABSTRACT FROM AUTHOR]

Plants with deficiency in Gibberellins (GAs) biosynthesis pathway are sensitive to exogenous GA3, while those with deficiency in GAs signaling pathway are insensitive to exogenous GA3. Thus, exogenous GA3 test is often used to verify whether the reduced height (Rht) gene is involved in GAs biosynthesis or signaling pathway. In the present study, we identified the genetic factors responsive to exogenous GA3 at the seedling stage of common wheat and analyzed the response of the plant height related quantitative trait loci (QTL) to GA3 to understand the GAs pathways the Rhtparticipated in. Recombinant inbred lines derived from a cross between KN9204 and J411 with different response to exogenous GA3 were used to screen QTL for the sensitivity of coleoptile length (SCL) and the sensitivity of seedling plant height (SSPH) to exogenous GA3. Two additive QTL and two pairs of epistatic QTL for SCL were identified, meanwhile, two additive QTL and three pairs of epistatic QTL for SSPH were detected. For the adult plant height (PH) investigated in two environments, six additive QTL were identified. Three QTL qScl-4B, qSsph-4Band qPh-4Bwere mapped in one cluster near the functional marker Rht-B1b. When PH were conditional on SSPH, the absolute additive effect value of qPh-4Band qPh-6Bwere reduced, suggesting that the Rhtsin both two QTL were insensitive to exogenous GA3, while the additive effect values of qPh-2B, qPh-3A, qPh-3Dand qPh-5Awere not significantly changed, indicating that the Rhtsin these QTL were sensitive to exogenous GA3, or they were not expressed at the seedling stage.

Shape memory polymers (SMPs) are smart materials that alter their shape in response to external stimuli. Dual-shape SMPs are widely recognized and are characterized by two shapes involved in a typical shape memory cycle. Recently, triple-shape memory polymers (TSMPs) have been introduced that have the ability to remember three shapes. Thermo-sensitive TSMPs can perform two sequential shape changes in response to heat, which were programed previously in a triple-shape creation process (TSCP). TSMPs are technologically significant as their development of has led to emergence of many complex potential applications that cannot be achieved by dual-shape polymers (Zhao et al., 2013). Crystallizable TSMPs are a class of thermo-sensitive TSMPs, where the shape creation is due to formation of crystalline phases. Different TSCPs have been reported which enable to control the triple shape capability of these materials. In this work the mechanical behavior of TSMPs has been modeled using a framework that has been developed recently for studying crystallization in polymers (Rao, 2003; Rao and Rajagopal, 2001, 2002, 2004). The framework has been used successfully to model SMPs (Barot and Rao, 2006; Barot et al., 2008), light activated SMPs (Sodhi and Rao, 2010) and is based upon the theory of multiple natural configurations. The model has been used to simulate a uni-axial deformation cycle for different types of TSCPs and the results have been compared with experimental data. [ABSTRACT FROM AUTHOR]

Under partial discharge (PD), a gas-insulated switchgear (GIS) will produce SF6decomposition products. If the concentrations of these products are higher than the standard values, this indicates that the GIS equipment is faulty. Photoacoustic spectroscopy techniques show a high sensitivity and good stability and, furthermore, they can enable on-line monitoring, making them widely used in the detection of SF6decomposition products in GIS equipment. The basic principles of photoacoustic spectroscopy were introduced and a set of devices for the online detection of SF6decomposition based on non-resonant photoacoustics was designed and realized. According to the infrared spectral characteristics of the target gases, the appropriate narrowband filters and infrared radiation light source were selected. This detection system is able to continuously detect CO, SO2and CF4. Calibration experiments with different concentrations of CO, SO2and CF4were carried out and the results show that the photoacoustic signal and concentration have a perfect linear relationship and the detection limits for CO, SO2and CF4are 5.9116, 8.2824 and 5.5226 ppm. Relative errors of the single measurements of CO, SO2and CF4are all less than 10% and the system exhibits excellent stability in a continuous 12 hour measurement.

Grain yield (GY) and yield components (YC) were investigated using two F8: 9 RILs, comprising 229 and 485 lines, respectively. A conditional analysis was conducted to generate conditional values for GY independent of each YC. Then both unconditional and conditional values were analyzed to map QTLs with additive effect. In both RILs, up to 23 unconditional and conditional QTLs were detected. However, only two QTLs were identified repeatedly among environments. All QTLs, except for 4 detected in unconditional mapping, were also identified as conditional QTLs, whereas a number of QTLs were additionally detected in conditional mapping. The number of QTLs detected that affected GY was different with respect to component-special influences. Our results revealed that the contributions of YC influencing QTL expression related to GY differed.

A recombinant inbred line (RIL) population with 302 lines derived from a cross of Weimai 8 × Luohan 2 was used to identify the quantitative trait loci (QTL) for plant height (PH) in wheat (Triticum aestivumL.). Possible genetic relationships between PH and PH components (PHC), including spike length (SL) and internode length from the first to the fourth node counted from the top, abbreviated as FIITL, SITL, TITL and FOITL, respectively, were evaluated at the QTL level. A QTL for PH was mapped using data on PH and on PH conditioned by PHC using the IciMapping V3.0 software. Conditional QTL mapping proved that, at the QTL level, SL contributed the least to PH, followed by FIITL and FOITL, while TITL had the strongest influence on PH, followed by SITL. These results indicate that the conditional QTL mapping method can be used to evaluate possible genetic relationships between PH and PHC, and that it can efficiently and precisely reveal counteracting QTL, which will enhance our understanding of the genetic basis of PH in wheat.

To comprehensively understand the genetic basis of plant height (PH), quantitative trait locus (QTL) analysis for internode lengths, internode component indices and plant height component index (PHCI) were firstly conducted in the present study. Two related F8:9recombinant inbred line (RIL) populations comprising 485 and 229 lines were used. Two hundred and nine putative additive QTL for the eight traits were identified, 35 of which showed significance in at least three trials. Of these, at least 11 pairwise QTL were common to the two populations. PH components at the QTL level had different effects on PH, confirming our previous multivariate conditional analysis (Cui et al. 2011). Eleven major QTL that showed consistency in expression across environments should be of great value in the genetic improvement of PH in wheat. The results above will enhance the understanding of the genetic basis of PH in wheat.

Friction stir butt barrier welding, an improved method based on the friction stir butt welding process, in which a barrier was configured on the butt plate, was applied to the Cu–Al combination. The resultant Cu–Al joints presented good appearance when Al was adopted as the barrier. The pin shifting towards the Al side could improve the interior quality of the weld. However, the effect was limited when the pin offset increased to a certain value. As the tool rotation rate increased, the amount and size of the voids decreased first and then increased. There were two types of joint depending on the interfacial morphology: the smooth interface and the chaotic interface. When the pin offset was zero, the interface was occupied by large Cu fragments. As the pin offset increased, the joint interface transited first to the smooth type and then to the chaotic type. As the rotation rate increased, the laminate density around the interface decreased, and the sublayers in the laminates thinned.

Globally, prostate cancer is the most common malignancy among men and there is no biomarker for defining tumour invasion and progression. Guanosine-5′-triphosphate (GTP)-binding RAS-like 3 (ARHI)is a tumour suppressor gene that has been found to be downregulated in the prostate cancer cell line PC-3. MicroRNA 221 and 222 have been shown to regulate ARHIexpression negatively. This study evaluated tissue samples from patients with prostate cancer (n= 35) that were designated as aggressive or non-aggressive according to their Gleason grade.Expression of ARHIand microRNA 221 and 222 was measured by real-time reverse transcription-polymerase chain reaction. The level of ARHI mRNA was significantly lower in aggressive compared with nonaggressive prostate cancer tissue samples.In contrast, microRNA 221 and 222 levels were significantly higher in aggressive compared with non-aggressive prostate cancer tissue samples. Whether ARHIand microRNA 221 and 222 could be considered as biomarkers for disease progression in prostate cancer requires further investigation.

In some microelectromechanical system device fabrication, using fuming sulphuric acid to remove crosslinked SU-8 mould from integrated thick metal structures is an inexpensive and effective wet etching technique. The fabrication of stator for a suspended rotational microgyroscope, which has surface-micromachined structures integrated, was investigated to study the removal process of 250-µm thick SU-8 plating mould. Immersion time in the acid was a critical factor for complete removal of SU-8 mould without detectable damage to the nickel structures. Variation of etch rate was investigated every 0.5 h in the range from 0.5 to 6 h; 5 h was found to be a suitable time setting to remove 250-µm thick SU-8 mould. During the process, etch rate was measured slowing down from 110 µm/h in the first 0.5 h to 18 µm/h in the last 0.5 h. It was better to finish the whole removal process in a consistent manner because although taking sample out of the acid, cleaning, and immersing it back into the acid again was able to accelerate subsequent etch rate, metal structures were likely to be etched black. The etch rate which slowed down with the increase of etch time based on continuous etching provided useful reference for time control during SU-8 application for ultra-thick integrated microstructure fabrication.

This study evaluated the clinical significance of traumatic anterior shoulder instability (TASI) classification using double-contrast computed tomography (CT) arthrography. Patient were randomly assigned to two groups: group 1 (n= 62); and group 2 (n= 63). TASI symptom severity in group 1 was assessed using physical signs of shoulder trauma and conventional X-ray, CT and magnetic resonance imaging; these patients received either conservative management (with physical rehabilitation) or standard surgery. Group 2 underwent double-contrast CT arthrography to classify TASI; its findings formed the basis of subsequent management. At 24 months post-therapy, significant improvements in clinical outcomes were observed in group 2: Constant scores were higher and Western Ontario Shoulder Instability Index scores were lower. At 24 months, recurrence rates were 21.0% (13/62) in group 1 and 7.9% (5/63) in group 2. Findings suggested that TASI classification using double-contrast CT arthrography provided meaningful information thereby improving treatment efficacy.

A new rapid casting process based on gelcasting and stereolithography (SL) has been developed to fabricate integral ceramic moulds for complex castings. An overview of the fabrication process is demonstrated. It is shown that preparation for ceramic slurry, design of the process system, pyrolysis of the resin prototype, and integrity of the ceramic mould all play a significant role in the whole process. A hollow turbine blade with complex internal and external structure was taken as the case study to verify the feasibility and effectiveness of the proposed process.

Abstract: In this paper, hyaluronic acid hydrogels with open porous structure have been developed for scaffold of brain tissue engineering. A short peptide sequence of arginine–glycine–aspartic acid (RGD) was immobilized on the backbone of the hydrogels. Both unmodified hydrogels and those modified with RGD were implanted into the defects of cortex in rats and evaluated for their ability to improve tissue reconstruction. After 6 and 12 weeks, sections of brains were processed for DAB and Glees staining. They were also labeled with GFAP and ED1 antibodies, and observed under the SEM for ultrastructral examination. After implanting into the lesion of cortex, the porous hydrogels functioned as a scaffold to support cells infiltration and angiogenesis, simultaneously inhibitting the formation of glial scar. In addition, HA hydrogels modified with RGD were able to promote neurites extension. Our experiments showed that the hyaluronic acid-RGD hydrogel provided a structural, three-dimensional continuity across the defect and favoured reorganization of local wound-repair cells, angiogenesis and axonal growth into the hydrogel scaffold, while there was little evidence of axons regeneration in unmodified hydrogel.

The influence of solvent evaporation rate, in the dry-casting process, on crystallinity and morphology of crystallizable polymeric membrane was studied. Poly-l-lactic acid (PLLA) was taken as an example. The membranes were characterized by scanning electron microscopy (SEM) and differential scanning calorimetry (DSC). By controlling the solvent evaporation rate, samples with various crystallinities were prepared. From higher to lower crystallinity the membranes exhibit three types of surface morphology in sequence: granule, stripe and smooth.

Presents an overview of the development and prospect of nanobiotechnology in China. Development of a technique for the synthesis of porous hollow silica nanoparticles; Combination of traditional Chinese medicine and nanotechnology; Electrochemical strategies for DNA detection.

In this paper we describe the combined use of surface‐initiated atom transfer radical polymerization (ATRP) and a gas/solid reaction in the direct preparation of CdS‐nanoparticle/block‐copolymer composite shells on silica nanospheres. The block copolymer, consisting of poly(cadmium dimethacrylate) (PCDMA) and poly(methyl methacrylate) (PMMA), is obtained by repeatedly performing the surface‐initiated ATRP procedures in N,N‐dimethylformamide (DMF) solution at room temperature, using cadmium dimethacrylate (CDMA) and methyl methacrylate (MMA) as the monomers. CdS nanoparticles with an average size of about 3 nm are generated in situ by exposing the silica nanospheres coated with block‐copolymer shells to H2S gas. These synthetic core–shell nanospheres were characterized using transmission electron microscopy (TEM), dynamic light scattering (DLS), thermogravimetric analysis (TGA), diffuse reflectance UV‐vis spectroscopy, X‐ray photoelectron spectroscopy (XPS), and powder X‐ray diffraction (XRD). These composite nanospheres exhibit strong red photoluminescence in the solid state at room temperature.

A designed hierarchical structure was made by self-assembly of nano-fibrils of mineralized collagen resembling extracellular matrix. The collagen fibrils were formed by self-assembly of collagen triple helices. Hydroxyapatite (HA) crystals grew on the surface of these fibrils in such a way that their c-axes were oriented along the longitudinal axes of the fibrils. The mineralized collagen fibrils aligned parallel to each other to form mineralized collagen fibers. For the first time, the new hierarchical self-assembly structure of collagen−hydroxyapatite composite was verified by conventional and high-resolution transmission electron microscopy.

Porous nano-hydroxyapatite/collagen/alginate (nHAC/Alginate) composite containing nHAC and Ca-crosslinked alginate is synthesized biomimetically. This composite shows a significant improvement in mechanical properties over nHAC material. Mechanical test results show that the compressive modulus and yield strength of this composite are in direct proportion to the percentage of Ca-crosslinked alginate in the composite. Primary biocompatibility experiments in vitro including fibroblasts and osteoblasts co-culture with nHAC/alginate composite indicated the high biocompatibility of this composite. Therefore the composite can be a promising candidate of scaffold material for bone tissue engineering.

Precalcification of Polyactive® 10007030 with a biomimetic calcium phosphate coating is expected to enhance the bioactivity of this biodegradable polymer for the application as bone filler or scaffold of bone tissue engineering. This study presents a 1day onestep incubation method to obtain either amorphous or bonelike apatitic calcium phosphate coating on Polyactive® 10007030. Either dense plates or threedimensional porous blocks of the polymer were incubated in a simplified but concentrated simulated body fluidderived solution at 37°C. By bubbling CO2gas, a solution was prepared with calcium and phosphate ion concentrations five times of that of regular simulated body fluid. With controlled stirring, the CO2was released out of the solution and exchanged by air. The pH of the solution increased to induce coating formation. Adjusting stirring rate and CO2air exchange rate controlled the process kinetics. The reaction kinetics had little influence on the crystallographic structure of the final coating mineral for a given solution composition as shown by Fourier transform infrared spectroscopy and Xray diffraction. However, the interface structure between the coating and substrate was kineticsdependent. A fast precipitation condition resulted in a uniform but superficial calcification pattern at the surface of polymer. A slow process by selecting either a slow stirring or a slow CO2air exchange, on the contrary, induced a localized but deep inside calcification pattern. A tensile test showed no statistically significant difference in the mechanical properties among uncoated and coated polymers. The cracking behavior of coatings from different kinetics, however, exhibited different manners, as can be attributed to different interface structures and interfacial strengths. © 2001 Wiley Periodicals, Inc. J Biomed Mater Res 59: 535–546, 2002

MCM-41 silica particles with several morphologies have been controllably synthesized with a basic medium. Nanospherical MCM-41 silica with an average size of 110 nm was produced through reaction of extremely low surfactant concentrations of CTAB with TEOS in the sodium hydroxide medium at 353 K, while a submicrometer-sized silica rod, 0.3−0.6 μm in diameter and 1 μm in length, and micrometer-sized oblate silica with nominal diameter around 1 μm were synthesized in aqueous ammonia, where the size and the morphology were controlled by varing the content of the solvent. A morphogenetic mechanism that is based on the deposition of self-assembled silicate surfactant rodlike micelles is proposed and explains well the controllability of the morphology.

To investigate the mechanism of inhibition of silver ions on microorganisms, two strains of bacteria, namely Gramnegative Escherichia coli E. coliand Grampositive Staphylococcus aureus S. aureus,were treated with AgNO3and studied using combined electron microscopy and Xray microanalysis. Similar morphological changes occurred in both E. coliand S. aureuscells after Agtreatment. The cytoplasm membrane detached from the cell wall. A remarkable electronlight region appeared in the center of the cells, which contained condensed deoxyribonucleic acid DNA molecules. There are many small electrondense granules either surrounding the cell wall or depositing inside the cells. The existence of elements of silver and sulfur in the electrondense granules and cytoplasm detected by Xray microanalysis suggested the antibacterial mechanism of silver: DNA lost its replication ability and the protein became inactivated after Agtreatment. The slighter morphological changes of S. aureuscompared with E. colirecommendeda defense system of S. aureusagainst the inhibitory effects of Agions. © 2000 John Wiley & Sons, Inc. J Biomed Mater Res, 52, 662–668, 2000.

An atomic intermixing layer, 25 nm in width, has been identified by highresolution transmission electron microscopy HRTEM and energydispersive Xray spectroscopy EDS analysis at the ceramicmetal interface of a hydroxyapatite HA coatingtitanium implant prepared by an ionbeamassisted deposition IBAD technique and post–heattreatment process. The detailed interfacial microstructure revealed a gradient evolution of both the structure and composition of the interfacial phases from the titanium substrate to HA coatings. An enhancement of the tensile bond strength was found and was attributed to the possible chemical bonding at the ceramicmetal interface. © 2000 John Wiley & Sons, Inc. J Biomed Mater Res, 52, 115–118, 2000.

Several types of calcium phosphatecollagen composites, including noncrystalline calcium phosphatecollagen, poorly crystalline carbonateapatite PCCAcollagen, and PCCA tetracalcium phosphatecollagen composites, were prepared through the mineralization of collagen matrix. The type I collagen was presoaked with a PO3−4containing solution and then immersed in a Ca2containing solution to allow mineral deposition. The solution of 0.56Msodium dibasic phosphate Na2HPO4 with a pH of nearly 14 was metastable and its crystallization produced Na2HPO4and sodium tripolyphosphate hexahydrate Na5P3O10· 6H2O, leading to a controlled release of orthophosphate ions during the subsequent mineral precipitation. The development of the composites was investigated in detail. The mineral contributed up to 60–70 of the weight of the final composites. The strength and Youngs modulus of the composites in tensile tests overlapped the lower range of values reported for bone. When implanted in muscle tissue, the composite showed biodegradability that was partly through a multinucleated giant cell mediated process. In a bone explant culture model it was observed that bonederived cells deposited mineralizing collagenous matrix on the composite. © 2000 John Wiley & Sons, Inc. J Biomed Mater Res, 50, 518–527, 2000.

The tissue response to a nano-hydroxyapatite/collagen composite implanted in a marrow cavity was investigated by histology and scanning electron microscopy. A Knoop microhardness test was performed to compare the mechanical behavior of the composite and bone. The ultrastructural features of the composite, especially the carbonate-substituted hydroxyapatite with low crystallinity and nanometer size, made it a bone-resembling material. It was bioactive, as well as biodegradable. At the interface of the implant and marrow tissue, solution-mediated dissolution and giant cell mediated resorption led to the degradation of the composite. Interfacial bone formation by osteoblasts was also evident. The process of implant degradation and bone substitution was reminiscent of bone remodeling. The composite can be incorporated into bone metabolism instead of being a permanent implant. For lack of the hierarchical organization similar to that of bone, the composite exhibited an isotropic mechanical behavior. However, the resistance of the composite to localized pressure could reach the lower limit of that of the femur compacta.© 1998 John Wiley & Sons, Inc. J Biomed Mater Res, 42, 540–548, 1998.

Crystallization temperature of the amorphous calcium phosphate coating synthesized by ionbeamassisted deposition successfully was decreased to 400°C for the making of orthopedic implants with better qualities. Transmission electron microscopy TEM and Xray diffraction XRD were used to investigate the morphological and structural evolution of the crystals in the coating during postheat treatment. The crystallization of calcium phosphate coating is a hydroxyldiffusioncontrolled process, which is thought to be the mechanism responsible for the decrease of the crystallization temperature. In addition, the detailed crystallization process of calcium phosphate coating is elaborated in the present paper. The results show that the crystallinity of the hydroxyapatite coating can be well controlled by adjusting the postheattreatment time. © 1999 John Wiley & Sons, Inc. J Biomed Mater Res, 46, 80–86, 1999.

Transplantation of osteogenic cells with a suitable matrix is one strategy for engineering bone tissue. Threedimensional distribution and growth of cells within the porous scaffold are of clinical significance for the repair of large bony defects. A nanoHApcollagen nHAC composite that mimics the natural bone both in composition and microstructure to some extent was employed as a matrix for the tissue engineering of bone. A porous nHAC composite was produced in sheet form and convolved to be a threedimensional scaffold. Using organ culture techniques and the convolving method, we have developed threedimensional osteogenic cellsnHAC constructs in vitro. Scanning electron microscopic and histological examination has demonstrated the development of the cellsmaterial complex. Spindleshaped cells migrating out of bone fragments continuously proliferated and migrated throughout the network of the coil. The porous nHAC scaffold provided a microenvironment resembling that seen in vivo, and cells within the composite eventually acquired a tridimensional polygonal shape. In addition, new bone matrix was synthesized at the interface of bone fragments and the composite. © 1999 John Wiley & Sons, Inc. J Biomed Mater Res, 44, 407–415, 1999.

Si+and N+ion implantation into medical poly(methyl methacrylate) (PMMA) were performed at an energy of 80 keV with fluences ranging from 5×1012to 5×1015ions/cm2at room temperature to improve blood compatibility. The results of the blood contacting measurementsin vitroshowed that the anticoagulability and anticalcific behaviour on the surface morphology were enhanced after ion implantation. No appreciable change in the surface morphology was detected by scanning electron microscopy (SEM). X-ray photoelectron spectroscopy (XPS) analysis indicated that ion implantation broke some original chemical bonds on the surface to form some new Si- and N-containing groups. These results were considered responsible for the enhancement in the blood compatibility of PMMA.

The microstructure, composition and the micromechanical properties across the thickness of femoral mid-diaphyses from 14 to 26 week human fetuses have been investigated. Scanning electron microscopy and transmission electron microscopy were employed to examine structural changes with maturation. The fetal bones consist of layers of woven bone. From young to old fetuses and from outer to inner bone layers, the collagen fibrils become more cross-linked, densely packed and change from disordered to an ordered arrangement. The collagen fibril bundles are also more preferentially oriented and change from a chiefly circumferential to longitudinal direction. The sizes of the apatite crystals also increase with age. The Ca/P ratio remains constant around 1.55 for all the bone layers except the outmost layer which is lower than 1.2. An nano-indenter was used to evaluate the microhardness and elastic modulus of each bone layer. The increase of microhardness and elastic modulus correlates with the maturation of bone. The mechanical properties of the mid-diaphyses of human fetal femurs are anisotropic, which is due to the preferential orientation of collagen fibrils

The deformation, fracture and toughening mechanisms of nacre from a kind of fresh-water bivalve mollusc (Cristaria plicata) were studied by SEM, TEM and microindentation tests. Experimental results revealed a strong anisotropy of the damage behaviour reflecting the microstructural character of nacre. The fractured surface parallel to the cross-sectional surface of nacre was much more tortuous than that parallel to the platelet surface. The crack line on the cross-sectional surface was step-like, while that on the platelet surface was polygonal. Sliding of aragonite layer combined with the plastic deformation of organic matrix is the main plastic deformation mechanism of nacre. Three main toughening mechanisms have been found acting in concert: crack deflection, fibre pull-out and organic matrix bridging.