Core/Shell Nanoparticles: Classes, Properties, Synthesis Mechanisms, Characterization, and Applications

The hydrothermal synthesis of zeolites: precursors, intermediates and reaction mechanism

2.3. Amorphous Minerals 4354 3. Biological Routes to Controlling Morphology 4354 3.1. General Mechanisms 4356 3.1.1. Soluble and Insoluble Organic Molecules 4356 3.1.2. Control over Crystal Polymorph 4357 3.1.3. Control over Crystal Orientation 4359 3.2. Single-Crystal Biominerals 4359 3.2.1. Organic and Inorganic Soluble Additives 4360 3.2.2. Templating of Single-Crystal Morphologies 4361 3.3. Polycrystalline Biominerals 4366 3.3.1. Nacre Formation in Mollusks 4366 3.3.2. ForaminiferasA Biogenic Mesocrystal 4368 3.4. Amorphous Biominerals 4370 3.4.1. Silicification in Diatoms 4370 3.4.2. In Vitro Studies of Silicification in Diatoms 4371 4. Bioinspired Routes to Controlling Crystal Morphologies 4371

Controlling Mineral Morphologies and Structures in Biological and Synthetic Systems

Novel insights into actions of bisphosphonates on bone: Differences in interactions with hydroxyapatite

This work studies the activity of activated CaO as a catalyst in the production of biodiesel by transesterification of triglycerides with methanol. Three basic aspects were investigated: the role of H 2 O and CO 2 in the deterioration of the catalytic performance by contact with room air, the stability of the catalyst by reutilization in successive runs and the heterogeneous character of the catalytic reaction. The characterization by X-ray diffraction (XRD), evolved gas analysis by mass spectrometry (EGA-MS) during heating the sample under programmed temperature, X-ray photoelectron (XPS) and Fourier transform-infrared (FT-IR) spectroscopies allowed to concluding that CaO is rapidly hydrated and carbonated by contact with room air. Few minutes are enough to chemisorb significant amount of H 2 O and CO 2 . It is demonstrated that the CO 2 is the main deactivating agent whereas the negative effect water is less important. As a matter of fact the surface of the activated catalyst is better described as an inner core of CaO particles covered by very few layers of Ca(OH) 2 . The activation by outgassing at temperatures ≥973 K are required to revert the CO 2 poisoning. The catalyst can be reused for several runs without significant deactivation. The catalytic reaction is the result of the heterogeneous and homogeneous contributions. Part of the reaction takes place on basic sites at the surface of the catalyst, the rest is due to the dissolution of the activated CaO in methanol that creates homogeneous leached active species.

Biodiesel from sunflower oil by using activated calcium oxide

Vaterite growth and dissolution in aqueous solution. I, Kinetics of crystal growth

Vaterite growth and dissolution in aqueous solution III. Kinetics of transformation

Phase transformation of calcium carbonate polymorphs

Appearance of a solid phase from aqueous solution, known as precipitation, is responsible for the formation of numerous natural materials and technological products. Therefore, the knowledge on mechanisms of elementary processes involved in precipitation should be considered in the areas such as geology, oceanology, biomineralization, medicine, basic chemical and pharmaceutical industries, analytical and materials chemistry in particular. Calcium carbonates are a very suitable model system for investigations of these processes. Owing to their low solubility, a wide range of initial supersaturations can be achieved that direct to different conditions under which a particular process dominates. Calcium carbonates can precipitate in the form of six modifications (polymorphic or hydrated). In the Laboratory for Precipitation Processes, systematic investigations of the conditions for formation, crystal growth and transformation of amorphous calcium carbonate, calcium carbonate hexahydrate, calcium carbonate monohydrate, vaterite and calcite have been performed during the last nearly twenty years. An overview of these studies is presented.

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Damir Kralj

Papers

Vaterite growth and dissolution in aqueous solution. I, Kinetics of crystal growth

Vaterite growth and dissolution in aqueous solution III. Kinetics of transformation

Phase transformation of calcium carbonate polymorphs

On calcium carbonates: from fundamental research to application

On Calcium Carbonates: From Fundamental Research to Application