نتایج جستجو برای: carbonates

تعداد نتایج: 9055  

Journal: :Science 2012
Estelle Couradeau Karim Benzerara Emmanuelle Gérard David Moreira Sylvain Bernard Gordon E Brown Purificación López-García

Cyanobacteria have affected major geochemical cycles (carbon, nitrogen, and oxygen) on Earth for billions of years. In particular, they have played a major role in the formation of calcium carbonates (i.e., calcification), which has been considered to be an extracellular process. We identified a cyanobacterium in modern microbialites in Lake Alchichica (Mexico) that forms intracellular amorphou...

2009
Liang-Nian He Jin-Quan Wang Jing-Lun Wang

The development of catalytic methods for chemical transformation of CO2 into useful compounds is of paramount importance from a standpoint of C1 chemistry and so-called green chemistry. The kinetic and thermodynamic stability of CO2 molecule presents significant challenges in designing efficient chemical transformations based on this potential feedstock. In this context, efforts to convert CO2 ...

2009
Pietro Tundo Fabio Aricò Anthony E. Rosamilia Maurizio Rigo Andrea Maranzana Glauco Tonachini

A series of dialkyl and methyl alkyl carbonates has been synthesized and their reactivity investigated. The behavior of preferential leaving and entering groups for the newly synthesized carbonates has been accurately investigated. Both experimental and computational studies agreed that the scale of leaving groups follows the trend: PhCH2O –, MeO– ≥ EtO–, CH3(CH2)2O –, CH3(CH2)7O – > (CH3)2CHO ...

2010
Christopher M. Gribble Peter Matthews Daniel Gantenbein

“Stickies” are tacky species, present in recycled paper and coated broke, derived from coating formulations, adhesives etc. They impact negatively on paper quality and cause web runnability problems by deposit build-up. To sustain recycling, stickies are controlled by adsorbing them onto minerals added to the recycled stock. We report isotherms for a fatty acid ester defoamer and an acrylic aci...

2013
Elizabeth Foran Steve Weiner Maoz Fine

The main source of calcium carbonate (CaCO₃) in the ocean comes from the shells of calcifying planktonic organisms, but substantial amounts of CaCO₃ are also produced in fish intestines. The precipitation of CaCO₃ assists fish in intestinal water absorption and aids in whole body Ca²⁺ homeostasis. Here we report that the product formed in the intestinal lumen of the gilt-head seabream, Sparus a...

Journal: :Nature communications 2013
Wei Chen Vadim S Kamenetsky Antonio Simonetti

The Earth's sole active carbonatite volcano, Oldoinyo Lengai (Tanzania), is presently erupting unique natrocarbonatite lavas that are characterized by Na- and K-bearing magmatic carbonates of nyerereite [Na2Ca(CO3)2] and gregoryite [(Na2,K2,Ca)CO3]. Contrarily, the vast majority of older, plutonic carbonatite occurrences worldwide are dominated by Ca-(calcite) or Mg-(dolomite)-rich magmatic car...

2018
Engel Kondrat

Cyclic carbonates are valuable chemicals for the chemical industry and thus, their efficient synthesis is essential. Commonly, cyclic carbonates are synthesised in a two-step process involving the epoxidation of an alkene and a subsequent carboxylation to the cyclic carbonate. To couple both steps into a direct oxidative carboxylation reaction would be desired from an economical view point sinc...

Journal: :Nature communications 2016
Ming-Yu Zhao Yong-Fei Zheng Yan-Yan Zhao

Authigenic carbonate was recently invoked as a third major global carbon sink in addition to primary marine carbonate and organic carbon. Distinguishing the two carbonate sinks is fundamental to our understanding of Earth's carbon cycle and its role in regulating the evolution of atmospheric oxygen. Here, using microscale geochemical measurements of carbonates in Early Triassic strata, we show ...

2016
Tobias Himmler Germain Bayon David Wangner Frieder Enzmann Jörn Peckmann Gerhard Bohrmann

Authigenic carbonate build-ups develop at seafloor methane-seeps, where microbially mediated sulphate-dependent anaerobic oxidation of methane facilitates carbonate precipitation. Despite being valuable recorders of past methane seepage events, their role as archives of atmospheric processes has not been examined. Here we show that cyclic sedimentation pulses related to the Indian monsoon in co...

Journal: :Physical chemistry chemical physics : PCCP 2012
Yannick Jeanvoine Pere Miró Fausto Martelli Christopher J Cramer Riccardo Spezia

Quantum chemical calculations were employed to elucidate the structural and bonding properties of La(III) and Lu(III) carbonates. These elements are found at the beginning and end of the lanthanoid series, respectively, and we investigate two possible metal-carbonate stoichiometries (tri- and tetracarbonates) considering all possible carbonate binding motifs, i.e., combinations of mono- and bid...

نمودار تعداد نتایج جستجو در هر سال

با کلیک روی نمودار نتایج را به سال انتشار فیلتر کنید