Control of crystalline phase and morphology of calcium carbonate by electrolysis: Effects of current and temperature

Calcium carbonate (CaCO3) can show various properties related to its different crystalline phases and is therefore a useful material for various applications. Wet processes are known to be suitable for preparing metastable CaCO3 polymorphs. Electrolysis has been proposed as a preparation method at ambient conditions. Although several electrolytic approaches have been reported, the effects of the applied current and temperature of the electrolyte on the crystalline phase and morphology of CaCO3 remain unclear. In the present study, we attempted the electrochemical preparation of CaCO3 particles under various electrolysis conditions and discuss the mechanism of CaCO3 particle formation. The crystalline phases and morphologies of the CaCO3 precipitates markedly changed depending on the applied current and method of cooling the electrolyte. We assume that these factors were governed by the degree of change in temperature, supersaturation, and pH of the electrolyte that were induced by differences in the electrolysis current

Effect of metallographic structure and machining process on the apatite-forming ability of sodium hydroxide- and heat-treated titanium

Although titanium (Ti) is clinically used for hard tissue reconstruction, it has low bone-bonding ability, i.e. bioactivity. Materials able to deposit apatite on their surfaces within the body is considered to exhibit bioactivity. Effects of the metallographic structure and machining process of Ti on its apatite-forming ability remains unclear. In this study, Ti substrates subjected to various preheating and machining processes were then subjected to NaOH and heat treatments. The apatite-forming abilities of resulting Ti were examined in simulated body fluid (SBF). Preheating of the Ti decreased its reactivity with NaOH solution. When quenched or annealed Ti was subjected to NaOH and heat treatments, the induction period for apatite formation in SBF slightly increased. This was attributed to a decrease in sodium titanate and increase in rutile on the Ti surface after the treatments. Substrates subjected to wire-electrical-discharge machining did not form apatite. This was attributed to the inhibition of PO43− adsorption on their surfaces following Ca2+ adsorption, which is an essential process for apatite nucleation. Contamination of Ti surface by components of the brass wire used in the machining contributed to the inhibition. The bioactivity of surface-modified Ti was therefore significantly affected by its thermal treatment and machining process

A characterization of collections of two-point sets with the uniqueness property

We give a sufficient condition for a collection of two-point sets to have the uniqueness property for meromorphic functions

A concept to facilitate musical expression

In this paper, we propose a concept for helping performers to freely demonstrate their musical expression. This approach divides all of the musical elements into non-expressive elements and expressive elements and allows the performer to directly manipulate the performance with the expressive elements. We illustrate three prototype systems based on the concept and evaluate their effectiveness through the systems’ subjective experiments. The results of the experiments suggest the possibility of our concept as well as effectiveness. In addition, we discuss an essential feature of musical performance and the role of a facilitating system for musical performance