Search results for "CARBONATE"

Process parameters of microsphere preparation based on propylene carbonate emulsion-precursors.

2020

This study aimed for a detailed understanding of the impact of different process parameters involved during celecoxib-loaded microsphere preparation based on propylene carbonate emulsion-precursors.Microspheres were prepared by a modified emulsification-solvent extraction method. Performed investigations included polymer solubility and viscosity, microsphere size, morphology and stability, propylene carbonate content as well as celecoxib solid state, content and release.Rough-walled round microspheres with sizes between 21 µm and 122 µm and an internal sponge-like structure filled with residual propylene carbonate (content between 1.9 ± 0.1% and 6.7 ± 0.5% w/w) were obtained. Encapsulation …

Self-Healing Properties of Bioinspired Amorphous CaCO3/Polyphosphate-Supplemented Cement

2020

There is a strong interest in cement additives that are able to prevent or mitigate the adverse effects of cracks in concrete that cause corrosion of the reinforcement. Inorganic polyphosphate (polyP), a natural polymer that is synthesized by bacteria, even those on cement/concrete, can increase the resistance of concrete to progressive damage from micro-cracking. Here we use a novel bioinspired strategy based on polyP-stabilized amorphous calcium carbonate (ACC) to give this material self-healing properties. Portland cement was supplemented with ACC nanoparticles which were stabilized with 10% (w/w) Na&ndash

Multistep Crystallization Pathways in the Ambient‐Temperature Synthesis of a New Alkali‐Activated Binder

2021

CO2: from waste to resource for methanol-based processes

2009

This paper reports on research aiming at developing sustainable processes for the production of methanol (CH3OH) and dimethyl carbonate (DMC, (CH3)2CO3) using carbon dioxide (CO2) as a raw material. Using carbon dioxide as a raw material has several advantages; it is non-toxic, in abundant supply, and promises innovative routes to the production of commodity chemicals. Methanol and dimethyl carbonate are important products and feedstocks of the chemical industry. Methanol is produced commercially from synthesis gas, but it is also possible to use carbon dioxide as a feedstock. Conventional production of dimethyl carbonate involves the use of toxic phosgene or carbon monoxide, while the met…

Insights into the In Vitro Formation of Apatite from Mg‐Stabilized Amorphous Calcium Carbonate

2020

On the mechanism of fibril growth in polycarbonate and poly(methyl methacrylate) crazes

1982

Effect of annealing below the glass transition on the loss peak of glassy polycarbonate

1980

Carbonate precipitation in the alkaline lake Specchio di Venere (Pantelleria Island, Italy) and the possible role of microbial mats

2016

Abstract Alkaline lakes like the hydrothermally affected lake Specchio di Venere (Pantelleria Island, Central Mediterranean) are typical geological settings harbouring calcified microbial mats. The present work is focused on the discrimination between biotic and abiotic processes driving carbonate precipitation in this lake, using hydrochemical, mineralogical and isotopic data. Hydrochemical analyses demonstrate that the lake is nearly 10−fold supersaturated with regard to aragonite and seasonally reaches hydromagnesite supersaturation. Microscopic observations depict organosedimentary laminated structures consisting of microbial communities and aragonitic precipitates, which are rather dis…

Paleoclimatic control of biogeographic and sedimentary events in Tethyan and peri-Tethyan areas during the Oxfordian (Late Jurassic)

2005

International audience; The paleobiogeographical distribution of Oxfordian ammonites and coral reefs in northern and Central Europe, the Mediterranean area, North and East Africa, and the Middle East and Central Asia is compared with the distribution in time and space of the most important lithofacies. Interest in the Oxfordian is focused on changes in facies and in biogeographical patterns that can be interpreted as the results of climatic events. Paleotemperature trends inferred from oxygen isotopes and paleoclimatic simulations are tested against fossil and facies data. A Late Callovian–Early Oxfordian crisis in carbonate production is indicated by the widespread absence of Lower Oxfordi…

Pedogenic carbonates and carbon pools in gypsiferous soils of a semiarid Mediterranean environment in south Italy

2013

Abstract Soil carbonates are key features in soils of arid and semiarid environment, playing an important role from pedogenetic, landscape history, paleoclimatic and environmental points of view. The objectives of this work were (i) to study pathways of pedogenic carbonate (PC) formation, (ii) to distinguish between lithogenic and pedogenic inorganic C by using the natural C isotope abundance, and (iii) to estimate the soil C pools in a gypsiferous semiarid Mediterranean environment (Sicily, Italy). Five soil pedons developed on calcareous and non-calcareous parent materials from Holocene (10,000 years BP) to Upper Tortonian (7.2–5.3 Ma BP) in age were surveyed. During field soil descriptio…