Search results for "Catalysis"

Enantiomerization of an inherently chiral resorcarene derivative: determination of the interconversion barrier by computer simulation of the dynamic …

2001

Abstract The inherently chiral tetrabenzoxazine resorcarene derivative 1 shows characteristic plateau-formation during enantioselective HPLC separation on the chiral stationary phase Chiralpak AD. By computer assisted peak form analysis of the elution profiles, obtained from temperature dependent dynamic HPLC (DHPLC) experiments, with ChromWin, the enantiomerization barrier Δ G # (298 K)=92±2 kJ mol −1 and the activation parameters Δ H # =53.0±1.8 kJ mol −1 and Δ S # =−131±14 J (K mol) −1 were determined.

Toxicity of vanadium during development of sea urchin embryos: bioaccumulation, calcium depletion, ERK modulation and cell-selective apoptosis

2022

Vanadium toxicology is a topic of considerable importance as this metal is widely used in industrial and biomedical fields. However, it represents a potential emerging environmental pollutant because wastewater treatment plants do not adequately remove metal compounds that are subsequently released into the environment. Vanadium applications are limited due to its toxicity, so it is urgent to define this aspect. This metal is associated with sea urchin embryo toxicity as it perturbs embryogenesis and skeletogenesis, triggering several stress responses. Here we investigated its bioaccumulation and the correlation with cellular and molecular developmental pathways. We used cytotoxic concentra…

Metal-free polymerization of phenylsilane: tris(pentafluorophenyl)borane-catalyzed synthesis of branched polysilanes at elevated temperatures.

2013

The strong organoborane Lewis acid B(C6F5)3 catalyzes the polymerization of phenylsilane at elevated temperatures forming benzene and SiH4 as side-products. The resulting polymer is a branched polysilane with an irregular substitution pattern, as revealed by 2D NMR spectroscopy. Having explored the mechanism of this novel metal-free polymerization by computational chemistry methods at the DFT level, we have suggested that unusual cationic active species, namely monomer-stabilized silyl cations, propagate the polymerization. Hydride abstraction of SiH3 moiety by the catalyst in the initiation step was found to be kinetically preferred by around 9 kcal mol(-1) over activation by coordination …

Molecular Endocrinology and Metabolism in 2021: What’s New

2021

The last two years, despite the very serious COronaVIrus Disease-2019 (COVID-19) pandemic, have been quite productive in the field of molecular endocrinology and metabolism and our journal section has contributed extensively on that [...]

Synthesis and characterization of zinc carboxy–porphyrin complexes for dye sensitized solar cells

2018

Two zinc porphyrins, 2 and 8, have been synthesized. Porphyrin 8 displays better electronic communication between the dye and the TiO2 electrode. Photophysical measurements and electrochemistry experiments suggest that both porphyrins are very promising sensitizers for dye-sensitized solar cells (DSSCs). It was found that their molecular orbital energy levels favor electron injection and dye regeneration in DSSCs. Solar cells sensitized by 2 and 8 were fabricated, and it was found that they show power conversion efficiencies (PCEs) of 5.27% and 7.13%, respectively. Photovoltaic measurements (J–V curves) together with the incident photon-to-electron conversion efficiency spectra of the two c…

Book Review: Catalysis and Zeolites. Fundamentals and Applications. Edited by Jens Weitkamp and Lothar Puppe.

2001

Industrial Microreactor Process Development up to Production

2008

This chapter is about industrial applications of microprocess technology. Industry is not very active in publishing not only because of confidentiality reasons but also because of the absence of direct need for a corresponding profile. Thus, one cannot expect that the ongoing developments can be shown with a similar degree of completeness, clarity and detailedness, as this is possible for reviewing scientific contributions from academy with a wealth of peer-reviewed papers. Especially, the information of major interest of what has been transferred to production and how do the companies make profit with the new technology is usually kept secret. Thus, it has to be accepted that some informat…

REWAQUA: an advanced technology for water purification in sustainable aquaculture based on photocatalytic ozonation

2017

The present study has been undertaken in order to test the real potential of photocatalytic ozonation in a bench-scale recirculating aquaculture system working on a 180 L reef coral aquarium. Notably, this choice may be considered representative. In fact, (i) the system is virtually closed so that fresh water turnover is practically negligible, (ii) the presence of living organisms is highly diversified (corals, fishes, molluscs, echinoderms and crustaceans) and some of them are particularly sensitive to water quality, (iii) high salinity strongly puts a strain on the purification system. The hereby presented purification method has been named REWAQUA, which stands for REcycling Water for A…

Editorial overview: Green analytical chemistry

2019

International audience

Preparation of photocatalysts by chemical methodologies

2021

Abstract The synthesis of photocatalytic materials is an important task for obtaining better results in terms of activity and/or selectivity in photocatalysis. This chapter reports an overview of the main methodologies using physical techniques to obtain bulky, supported powders or films and coatings to be used as heterogeneous photocatalysts. The classical chemical methodologies for the preparation of photocatalytic materials are presented in the previous chapter, so the information presented here complements the aforementioned one. Materials scientists and engineers have made significant progresses in the improvement of methods of synthesis of nanomaterial solids by developing different a…