Optical properties of liquid pure copper by density functional theory.

The optical properties of pure liquid copper were investigated using density functional theory with the Quantum ESPRESSO package. The effects of structural changes were investigated by comparing the electron density of states and imaginary part of the dielectric function between the crystalline and liquid states with densities near the melting point. The results indicated that the effect of interband transitions remains in the structural changes near the melting point.

Uniformity evaluation of laser-induced periodic surface structures formed by two-color double-pulse femtosecond laser irradiation.

The Perpendicular Period and Phase Scanning (PS) method can evaluate the uniformity of a laser-induced periodic surface structure (LIPSS). PS assesses the uniformity of LIPSS using the standard deviation of the peak period and the average of the phase difference in the direction perpendicular to LIPSS. The PS method demonstrates that LIPSS formed by two-color double-pulse irradiation is reduced to a quarter of the period dispersion, and the average phase difference of LIPSS is also reduced compared to the single-pulse irradiation.

Meniscus surface texture is associated with degenerative changes in biological and biomechanical properties.

Meniscal degeneration is defined by semi-quantitative assessment of multiple histological findings and has been implicated in biomechanical dysfunction, yet little is known about its relationship with biological properties. This paper aimed to quantitatively evaluate degenerative findings in human meniscus to examine their relationship with gene expression and biomechanical properties, and to extract histological findings that reflect biological properties like gene expression and cytokine secretion. This study included lateral menisci of 29 patients who underwent total knee arthroplasty.

Articular surface integrity assessed by ultrasound is associated with biological characteristics of articular cartilage in early-stage degeneration.

Early diagnosis of articular cartilage damage and repeated evaluation of treatment efficacy are essential for osteoarthritis treatment. In this study, we established a simple ultrasound grading system for early degenerative articular cartilage and investigated its relationship with cartilage biological characteristics. The ultrasound grading system were based on surface integrity (S1a: continuous high-echo lines, S1b: discontinuous or weak high-echo lines, S2: surface irregular) and cartilage echogenicity (E1: with > 50%, E2: < 50% hypoechoic area of total cartilage layer) and verified by surface roughness (Ra; μm) and histological staining.

Directionally-Dependent Mechanical Properties of Ti6Al4V Manufactured by Electron Beam Melting (EBM) and Selective Laser Melting (SLM).

An investigation of mechanical properties of Ti6Al4V produced by additive manufacturing (AM) in the as-printed condition have been conducted and compared with wrought alloys. The AM samples were built by Selective Laser Melting (SLM) and Electron Beam Melting (EBM) in 0°, 45° and 90°-relative to horizontal direction. Similarly, the wrought samples were also cut and tested in the same directions relative to the plate rolling direction.

X-ray phase contrast observation of solidification and hot crack propagation in laser spot welding of aluminum alloy.

The inner characteristics of solidification and crack propagation in laser spot welding of four representative aluminum alloys, A1050, A2024, A5083 and A6061, were firstly observed with the X-ray phase contrast method. Keyhole disappeared within 1 ms after the laser was shut down. The solidification process finished in 2 ms for A1050, 3 ms for A2024, 5 ms for A5083, and 3 ms for A6061, respectively.

Response of preosteoblasts to titanium with periodic micro/nanometer scale grooves produced by femtosecond laser irradiation.

To investigate the cellular response to designed topography in vitro, we studied the adhesion, proliferation, osteogenic differentiation, and calcification of mouse preosteoblasts (MC3T3-E1) cultured on titanium (Ti) surfaces with periodic micrometer scale grooves containing nanometer scale ripples in the vertical direction fabricated by single-shot, femtosecond laser irradiation (fsTi). The surface composition and chemical state of fsTi were almost the same as those of mirror-polished Ti without femtosecond laser irradiation (mTi). Cells cultured on fsTi were highly aligned, whereas the cell proliferation rate on fsTi was less than that on mTi.

Hierarchical periodic micro/nano-structures on nitinol and their influence on oriented endothelialization and anti-thrombosis.

The applications of hierarchical micro/nano-structures, which possess properties of two-scale roughness, have been studied in various fields. In this study, hierarchical periodic micro/nano-structures were fabricated on nitinol, an equiatomic Ni-Ti alloy, using a femtosecond laser for the surface modification of intravascular stents. By controlling the laser fluence, two types of surfaces were developed: periodic nano- and micro/nano-structures.

Periodic nanostructures on titanium dioxide film produced using femtosecond laser with wavelengths of 388 nm and 775 nm.

Titanium dioxide (TiO2) film is an important biomaterial used to improve the biocompatibility of titanium (Ti). We have used a film coating method with an aerosol beam and femtosecond laser irradiation to form periodic structures on biomaterials for control of the cell spreading. The control of cell spreading on biomaterials is important for the development of advanced biomaterials.

Bioactive titanate nanomesh layer on the Ti-based bulk metallic glass by hydrothermal-electrochemical technique.

Titanate nanomesh layers were fabricated on Ti-based bulk metallic glass (BMG) to induce bioactivity in the form of apatite-forming ability. Titanate nanomesh layers were prepared by hydrothermal-electrochemical treatment at 90 degrees C for 2 h, with an aqueous solution of NaOH as an electrolyte. A constant electric current of 0.