Magnesium: properties and rich chemistry for new material synthesis and energy applications.

Magnesium (Mg) has many unique properties suitable for applications in the fields of energy conversion and storage. These fields presently rely on noble metals for efficient performance. However, among other challenges, noble metals have low natural abundance, which undermines their sustainability. Mg has a high negative standard reduction potential and a unique crystal structure, and its low melting point at 650 °C makes it a good candidate to replace or supplement numerous other metals in various energy applications. These attractive features are particularly helpful for improving the properties and limits of materials in energy systems. However, knowledge of Mg and its practical uses is still limited, despite recent studies which have reported Mg's key roles in synthesizing new structures and modifying the chemical properties of materials. At present, information about Mg chemistry has been rather scattered without any organized report. The present review highlights the chemistry of Mg and its uses in energy applications such as electrocatalysis, photocatalysis, and secondary batteries, among others. Future perspectives on the development of Mg-based materials are further discussed to identify the challenges that need to be addressed.

Dispersion Polymerization of Polystyrene Particles Using Alcohol as Reaction Medium.

In this study, monodisperse polystyrene nanospheres were prepared by dispersion polymerization using alcohol as reaction medium to prepare colloidal clusters of the latex beads. Polyvinylpyrrolidone (PVP) and 2-(methacryloyloxy)ethyltrimethylammonium chloride (MTC) were used as dispersion stabilizer and comonomer, respectively. The particle size could be controlled by adjusting the reactant compositions such as the amount of stabilizer, comonomer, and water in the reactant mixture. The size and monodispersity of the polymeric particles could be also controlled by changing the reaction medium with different alcohols other than ethanol or adjusting the polymerization temperature. The synthesized particles could be self-organized inside water-in-oil emulsion droplets by evaporation-driven self-assembly to produce colloidal clusters of the polymeric nanospheres.

Long-term evaluation of sealants applied with an invasive technique.

PURPOSE: To study the retention of sealants applied to the permanent molars using an invasive technique. METHODS: Sealants containing fillers were applied to 739 first permanent molars using an invasive technique. After a minimum period of 6 months (mean time lapse after treatment, 63.5 months; range 6 - 121 months), the overall retention, marginal integrity, and marginal discolouration were evaluated according to the period after treatment, the operator's experience, and the location of the tooth (maxillary or mandibular). RESULTS: The overall retention was 93.78%. The sealants and marginal integrity deteriorated with time and with less clinical experience. However, there was no significant difference between the maxillary and the mandibular teeth. Marginal discolouration occurred more frequently in the maxilla with time but there was no significant difference with the operator's experience. CONCLUSIONS: The retention rate and marginal integrity of sealants decreased with time and with less clinical experience of the operator, and more marginal discolouration developed in the maxillary teeth with time in comparison to the mandibular teeth.