In-vitro heat-generating and apatite-forming abilities of PMMA bone cement containing TiO2 and Fe3O4

Poly (methyl methacrylate) (PMMA) bone cement is widely used as a filler for repairing bone defects. To improve the effectiveness of the treatment for bone defects caused by metastatic bone tumours, we propose the formulation of PMMA cement containing titania (TiO₂) and magnetite (Fe₃O₄) that offers high bone affinity, making the cement suitable for use in magnetic hyperthermia. The TiO₂ and Fe₃O₄ contents of the PMMA cement varied from 20 to 45 mass%. The various cement samples were evaluated for their apatite-forming ability and heat-generation characteristics. The samples containing TiO₂ in concentrations of 15 mass% or higher formed apatite on their surfaces within 14 days in a simulated body fluid. The heat-generation characteristics of the samples were evaluated by applying an alternating current (AC) magnetic field under the following conditions: |H| = 40 Oe and f = 600 kHz, or |H| = 100 Oe and f = 100 kHz. The surface temperatures of the samples containing 25 and 30 mass% Fe₃O₄ reached 42.3 and 44.8 °C, respectively, at |H| = 40 Oe and f = 600 kHz. During hyperthermia treatment, cancer cells die at temperatures higher than 42 °C, and the cement samples fabricated in this study could reach this temperature. However, since some degree of heat loss will occur in vivo, it is necessary to ensure that the temperature is higher than 42 °C by varying the AC magnetic field. Nevertheless, the fact that the samples containing Fe₃O₄ concentrations of 25 mass% or higher generated enough heat under the AC magnetic field makes them suitable for clinical use in hyperthermia. Thus, PMMA cement containing 15 mass% or more of TiO₂ and 25 mass% or more of Fe₃O₄ should be investigated as a bioactive bone cement with a strong hyperthermia effect.     

Report on Microgravity Experiments of Dynamic Surface Deformation Effects on Marangoni Instability in High-Prandtl-Number Liquid Bridges

This paper reports an overview and some important results of microgravity experiments called Dynamic Surf, which have been conducted on board the International Space Station from 2013 to 2016. The present project mainly focuses on the relations between the Marangoni instability in a high-Prandtl-number (Pr=?67 and 112) liquid bridge and the dynamic free surface deformation (DSD) as well as the interfacial heat transfer. The dynamic free surface deformations of large-scale liquid bridges (say, for diameters greater than 10 mm) are measured with good accuracy by an optical imaging technique. It is found that there are two causes of the dynamic free surface deformation in the present study: the first is the time-dependent flow behavior inside the liquid bridge due to the Marangoni instability, and the second is the external disturbance due to the residual acceleration of gravity, i.e., g-jitter. The axial distributions of DSD along the free surface are measured for several conditions. The critical parameters for the onset of oscillatory Marangoni convection are also measured for various aspect ratios (i.e., relative height to the diameter) of the liquid bridge and various thermal boundary conditions. The characteristics of DSD and the onset conditions of instability are discussed in this paper.     

Effect of silicate incorporation on in vivo responses of α-tricalcium phosphate ceramics

In addition to calcium phosphate-based ceramics, glass-based materials have been utilized as bone substitutes, and silicate in these materials has been suggested to contribute to their ability to stimulate bone repair. In this study, a silicate-containing α-tricalcium phosphate (α-TCP) ceramic was prepared using a wet chemical process. Porous granules composed of silicate-containing α-TCP, for which the starting composition had a molar ratio of 0.05 for Si/(P + Si), and silicate-free α-TCP were prepared and evaluated in vivo. When implanted into bone defects that were created in rat femurs, α-TCP ceramics either with or without silicate were biodegraded, generating a hybrid tissue composed of residual ceramic granules and newly formed bone, which had a tissue architecture similar to physiological trabecular structures, and aided regeneration of the bone defects. Supplementation with silicate significantly promoted osteogenesis and delayed biodegradation of α-TCP. These results suggest that silicate-containing α-TCP is advantageous for initial skeletal fixation and wound regeneration in bone repair.     

Nanohybrid polymer prepared by successive polymerization of methacrylate monomer containing silver nanoparticles in situ prepared under microwave irradiation

The well-dispersed silver nanoparticles were prepared in reactive methacrylate monomers under microwave irradiation without polymerization. In contrast to conventional heating, the synthesis of Ag nanoparticles proceeded uniformly throughout the reaction vessel only under microwave irradiation, reaching the completion of the reaction simultaneously in the whole reaction solution. Successive polymerization of the monomer containing the resulting nanoparticles has successfully produced a monohybrid of the silver nanoparticles dispersed in polymer matrix.     

Crosslinking structure of keratin: III. Rubberlike elasticity originating from non-uniform structures of the swollen hair and wool fibers

Hair and wool fibers treated with an 11 M LiBr solution containing N-ethylmaleimide showed typical rubberlike elasticity in a solution composed of equal volumes of 8 M LiBr and diethylene glycol monobutyl ether. Stress–strain relations of the swollen fibers were treated with a two-phase structural model: a mechanically stable phase of higher crosslinked domains and a rubbery phase with lower crosslink density. Stress–strain curves were analyzed by applying non-Gaussian chain statistics to the swollen keratin network, including microdomains, which act as reinforcing filler particles in rubber. Swollen hair showed about 2.3 times higher modulus than wool. It has been suggested that: (1) the difference in the modulus between the two keratins is attributable to the difference in the volume fraction of domains, and (2) the crosslink density of rubbery phase in hair is virtually identical to that in wool.     

Thermodynamic model for Zr solubility in the presence of gluconic acid and isosaccharinic acid

Zr solubility in the presence of gluconic acid (GLU) and isosaccharinic acid (ISA) was investigated as a function of hydrogen ion concentration (pH_c) and the total concentration of GLU or ISA. The dependence of the increase in Zr solubility on the pH_c and GLU concentration suggested the existence of Zr(OH)₄(GLU)₂^2? in the neutral pH region and Zr(OH)₄(GLU)(GLU_-H)^3? in the alkaline pH region above pH_c 10 as the dominant species in the presence of 10^?3–10^?1 mol/dm³ (M) GLU. In the presence of ISA, the dominant species Zr(OH)₄(ISA)₂^2? and Zr(OH)₄(ISA)(ISA_-H)^3? were proposed to occur in the neutral and alkaline pH regions, similar to those found in the presence of GLU. From X-ray diffraction analysis, the solubility-limiting solid phase in the presence of GLU and ISA was considered to be Zr(OH)₄(am). The formation constants of the Zr gluconate and isosaccharinate complexes were determined by least-squares fitting analysis of the solubility data, and the obtained values were discussed in comparison with those of tetravalent actinides.     

矿井废水资源化(饮用级)新技术现场试验

以郑煤集团告成煤矿矿井废水处理为例,分析了以重力式可拆洗中空纤维超滤膜组件为核心、联用GAC滤料吸附与二氧化氯消毒处理矿井废水的工艺,此工艺的实施,有利于缓解我国水资源危机。     

High strength poly(vinyl alcohol) films obtained by drying and then stretching freeze/thaw cycled gel

The mechanical properties of stretched poly(vinyl alcohol) (PVA), which is formed by stretching a film prepared from a freeze/thaw cycled gel, were investigated as a function of the stretching ratio. The tensile strength and Young's modulus of 800% stretched PVA annealed at 130°C were 3.4 and 119 GPa, respectively. These values were much higher than those for a PVA film prepared without freeze/thaw cycling. For a film stretched more than 600% before annealing, two melting peaks, assignable to folded and extended chain crystals, were observed around 220°C and 230°C, respectively. This indicates that a shish‐kebab structure is formed as the stretching ratio increases. After annealing at 130°C, the folded‐chain crystal transformed to an extended‐chain crystal if an extended‐chain crystal was present in the stretched film before annealing. High tensile strength and Young's modulus after annealing were due to the formation of extended‐chain crystal. Therefore, the presence of extended‐chain crystal for annealing is important to provide good mechanical properties. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 41318.     

All-fiber broadband supercontinuum source with high efficiency in a step-index high nonlinear silica fiber

We demonstrate an all-fiber broadband supercontinuum (SC) source with high efficiency in a step-index high nonlinear silica fiber, which was pumped by a 1557 nm subpicosecond-pulse laser in the normal dispersion region. The broad SC spectrum covers the spectral range from 840 to 2390 nm, and the 10 dB bandwidth from 1120 nm to 2245 nm of the SC covers one octave, assuming the peaks near 1550 nm were filtered. The SC source system is constructed by all-fiber components, which can be fusion-spliced together directly with low loss, less than 0.1 dB. Thus the SC source has high energy transfer efficiency from the pump source. The maximum SC average power of 332 mW is obtained, including the peaks near 1550 nm. The spectral density for the 10 dB bandwidth is in the range from -17.3 to -7.3 dBm/nm.