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Abstract: This study investigated the bone regeneration properties of titanium fibre mesh as a tissue engineering material. A thin hydroxyapatite (HA) coating on the titanium fibre web was created using the developed molecular precursor method without losing the complex interior structure. HA-coated titanium fibre mesh showed apatite crystal formation in vitro in a human osteoblast culture. Titanium fibre mesh discs with or without a thin HA coating were implanted into rat cranial bone defects, and the animals were killed at 2 and 4 weeks. The in vivo experience revealed that the amount of newly formed bone was significantly higher in the HA-coated titanium fibre mesh than in the non-coated titanium fibre mesh 2 weeks after implantation. These results suggest that thin HA coating enhances osteoblast activity and bone regeneration in the titanium fibre mesh scaffold. Thin HA-coating improved the ability of titanium fibre mesh to act as a bone regeneration scaffold. [Copyright &y& Elsevier]

Abstract: This paper presents experimental results of lightning surges incoming into a customer due to lightning to an antenna of the customer, a pole and a ground nearby the customer, and briefly discusses lightning current distribution in the customer, a distribution line and a telephone line. Based on experimental results, modeling of each component is explained, and EMTP simulations are carried out. The ground voltage rise is represented by a mutual resistance between grounding electrodes. EMTP simulation results have been observed to agree qualitatively with the measured results, and it becomes possible to investigate lightning surges and current distribution in a customer by an EMTP simulation. [Copyright &y& Elsevier]

• This paper briefly summarizes various frequency-dependent (FD) soil models. • Wave propagations on underground cables are calculated by the FD soil models. • Surge simulations of cross-bonded cable using the FD soil models are studied. This paper investigates the influence of frequency-dependent (FD) soil parameters in comparison to the constant soil (CS) parameters on wave propagations and transient characteristics of underground cables. Various FD soil models are summarized, and the calculated results of the FD soil parameters are compared with independent measured FD soil data. Longmire / Smith (LS) model is found to show the best agreement with the measured results. The frequency responses of wave propagations on underground cables are studied by the recently proposed extended transmission line (TL) approach together with the CS and the LS FD soil models. Calculated transient responses show more attenuation with a large soil resistivity at 100 Hz in comparison with those with a small soil resistivity at 100 Hz. Further, the transient voltage responses of a cross-bonded cable are compared with the transients solved by the Cable Constants and the existing FD soil routine in an EMT-type simulation tool, and a significant difference is observed. [ABSTRACT FROM AUTHOR]

Coating biomaterials with a thin hydroxyapatite (HA) was proven effective in enhancing bone compatibility. Segmental bone defects are considered as the most difficult defect to repair in bone regeneration therapy. We developed submicron-thin HA-coated titanium fiber mesh scaffolds to reconstruct immediately loaded segmental mandibular defects and evaluated their bone compatibility in vitro and in vivo . Human osteoblasts attachment, proliferation, and osteocalcin expression in non- and HA-coated scaffolds were evaluated. A 10-mm long segmental bone defect in a rabbit mandibular bone was reconstructed with non- or HA-coated scaffolds, which were removed at 9 and 21 weeks, to evaluate the mechanical strength of the bone-scaffold connection and the bone formation around the scaffold. Expression of osteocalcin was greater in HA-coated scaffolds. In vivo bone formation in HA-coated scaffolds was greater than that in non-coated scaffolds at 21 weeks. Newly formed bone in HA-coated scaffolds mostly restored bone continuity. Scanning electron microscopy identified strong integration of the bone and HA-coated scaffolds. The mechanical strength of the bone-scaffold connection was 3-fold greater in HA-coated scaffolds than that in non-coated scaffolds. These results suggest that a thin HA-coated titanium fiber mesh scaffold is a bone-compatible mandibular reconstruction device in immediately loaded segmental defects. [ABSTRACT FROM AUTHOR]

We compared osteoblast and osteoclast differentiation when using beta-tricalcium phosphate (βTCP) and titanium scaffolds by investigating human mesenchymal stem cells (hMSCs) and osteoclast progenitor cell activities. hMSCs were cultured for 7, 14, and 21 days on titanium scaffolds with 60%, 73%, and 87% porosity and on βTCP scaffolds with 60% and 75% porosity. Human osteoclast progenitor cells were cultured with osteoblast for 14 and 21 days on 87% titanium and 75% βTCP scaffolds. Viable cell numbers with 60% and 73% titanium were higher than with 87% titanium and βTCP scaffolds ( P < 0.05). An 87% titanium scaffold resulted in the highest osteocalcin production with calcification on day 14 ( P < 0.01) in titanium scaffolds. All titanium scaffolds resulted in higher osteocalcin production on days 7 and 14 compared to βTCP scaffolds ( P < 0.01). Osteoblasts cultured on 87% titanium scaffolds suppressed osteoclast differentiation on day 7 but enhanced osteoclast differentiation on day 14 compared to 75% βTCP scaffolds ( P < 0.01). These findings concluded that high porosity titanium scaffolds could enhance progression of hMSC/osteoblast differentiation and regulated osteoclast differentiation cooperating with osteoblast differentiation for calcification as compared with lower porous βTCP. [ABSTRACT FROM AUTHOR]

• This research presents a simplified corona discharge model adopted with a PEEC method for simulation of lightning over-voltage surge. • The effect on the voltage measuring system to the induced voltage on its nearby parallel wire is presented and discussed. • Undesired oscillations of the computed voltage and current waveforms found in the results of the previous authors' paper have been discarded. • The PEEC method with the corona model is an attractive candidate for simulations of lightning surges propagating along overhead wires. In this paper, a simplified corona discharge model is adopted with a partial element equivalent circuit (PEEC) method in the time domain for simulation of lightning over-voltage surge. Effects of corona discharge to the voltage distortion and the electromagnetic coupling of the overhead wires are presented. In addition, the effect on the voltage measuring system to the induced voltage on its nearby parallel wire is presented and discussed. The corona progression from an overhead wire, to which a high voltage impulse is applied, is represented by the radial expansion of the conducting region. Undesired oscillations of the computed waveforms found in the authors' previous paper have been discarded by iteration process for calculation of the corona radius and the voltage of each PEEC element at each calculated time step. To confirm the validity of the presented model with the PEEC method, the calculated results are compared with experimental results. The calculated results agree well with the corresponding experimental ones. This shows that the PEEC method in the time domain with the corona model is of use in simulations of lightning surges propagating along overhead wires. [ABSTRACT FROM AUTHOR]