Precious metal-free Fe-N-C catalysts efficiently electrocatalyze the oxygen reduction reaction both in acid and alkaline electrolyte. Their stability is however limited acidic medium, but generally accepted to be much higher Herein, by combining advanced electron X-ray based techniques, we provide comprehensive evidence of a Fe dissolution/reprecipitation mechanism, which partially transforms s...

Abstract Pyrite geochemistry has proven useful for tracking changes in the composition and physico-chemical conditions of hydrothermal fluids ore-forming environments. Here, we investigated microtextural features chemical pyrite, a main Au-bearing phase Akeshi Kasuga deposits (Southern Kyushu, Japan), to better constrain processes these high-sulfidation epithermal Au deposits. Despite widesprea...

Статья посвящена химической модификации природного полимера хитозана с целью повышения его качества и пригодности для дальнейшего синтеза наночастиц пленок. Были синтезированы образцы хитозана, очищенные гидроксидом натрия последующим переосаждением, обладающие повышенной степенью деацетилирования сниженной молекулярной массой. Также обработкой янтарной кислотой, цистеином, соляной кислотой пол...

Abstract Recent studies have identified gold nanoparticles in ores a range of deposit types, but little is known about their formation processes. In this contribution, gold-bearing magnetite from the well-documented, world-class Beiya Au deposit, China, was investigated terms microstructure and crystallography at nanoscale. We present first three-dimensional (3D) focused ion beam/scanning elect...

Abstract This work shows that the titanium dioxide coatings obtained by low-pressure cold gas spraying with use of sol–gel amorphous TiO 2 powder are characterized photocatalytic activity despite their partial content. Moreover, research outcome suggests decomposition rate organic pollutants is enhanced after long-term exposure to moisture. The condensation humidity test not detrimental continu...

manganese ore deposits occurred in various types of syngenetic, diagenetic and epigenetic mineralization in association with radiolarian cherts in colored melange of neyriz ophiolite in abadeh tashk area, eastern fars province. microscopic study and xrd analyses show a simple mineralogy for manganese compounds in all types. psylomelane and braunite are the primary manganese compounds in syngene...

The exchange of Ca2+ ions in hydroxyapatite (HAp) with Zn2+ into Zn-HAp is interest for applications ranging from bone tissue engineering to the use as a precursor subsequent ion-exchange reactions. Previous studies, using direct synthesis, showed that ~ 20 mol% can be incorporated HAp, before byproducts are observed. However, this realized at cost loss crystallinity and control over crystal si...

In part I of this study we aim to evaluate and control the characteristics of the powders constituting the solid phase of a vaterite CaCO(3)-dicalcium phosphate dihydrate cement using a co-grinding process and to determine their impact on cement setting ability. An original methodology involving complementary analytical techniques was implemented to thoroughly investigate the grinding mechanism...