Oxygen and nitrogen enriched pectin-derived micro-meso porous carbon for CO2 uptake

Oxygen and nitrogen enriched micro–meso porous carbon powders have been prepared from pectin and melamine as oxygen and nitrogen containing organic precursors, respectively.

Support–Activity Relationship in Heterogeneous Catalysis for Biomass Valorization and Fine-Chemicals Production

Heterogeneous catalysts are progressively expanding their field of application, from high-throughput reactions for traditional industrial chemistry with production volumes reaching millions of tons per year, a sector in which they are key players, to more niche applications for the production of fine chemicals. These novel applications require a progressive utilization reduction of fossil feedstocks, in favor of renewable ones. Biomasses are the most accessible source of organic precursors, having as advantage their low cost and even distribution across the globe. Unfortunately, they are intrinsically inhomogeneous in nature and their efficient exploitation requires novel catalysts. In this process, an accurate design of the active phase performing the reaction is important; nevertheless, we are often neglecting the importance of the support in guaranteeing stable performances and improving catalytic activity. This review has the goal of gathering and highlighting the cases in which the supports (either derived or not from biomass wastes) share the worth of performing the catalysis with the active phase, for those reactions involving the synthesis of fine chemicals starting from biomasses as feedstocks.

From the Formation of the Earth to the Establishment of Luka

The article discusses successive stages in the evolution of life up to the establishment of the prokaryotic cell emphasizing the transitions from pre-biotic environment to organic precursors, pre-RNA-RNA, RNA-proteins-DNA, DNA-LUCA. They are paired with the development of pre-biotic structural progenitors of a cell - micelles, vesicles, protocells, prokaryotic ancestor, two prokaryotic branches – Eubacteria and Archaebacteria. The driving force is the natural selection (chemical, biochemical and biological), maintaining the correspondence between the emerging structures and their environment.

Surface Properties and Morphology of Boron Carbide Nanopowders Obtained by Lyophilization of Saccharide Precursors

The powders of boron carbide are usually synthesized by the carbothermal reduction of boron oxide. As an alternative to high-temperature reactions, the development of the carbothermal reduction of organic precursors to produce B4C is receiving considerable interest. The aim of this work was to compare two methods of preparing different saccharide precursors mixed with boric acid with a molar ratio of boron to carbon of 1:9 for the synthesis of B4C. In the first method, aqueous solutions of saccharides and boric acid were dried overnight at 90 °C and pyrolyzed at 850 °C for 1 h under argon flow. In the second method, aqueous solutions of different saccharides and boric acid were freeze-dried and prepared in the same way as in the first method. Precursors from both methods were heat-treated at temperatures of 1300 to 1700 °C. The amount of boron carbide in the powders depends on the saccharides, the temperature of synthesis, and the method of precursor preparation.

In-Situ Photo-Dissociation and Polymerization of Carbon Disulfide with Vacuum Ultraviolet Microplasma Flat Lamp for Organic Thin Films

Vacuum UV (VUV) photo-dissociation for a liquid phase organic compound, carbon disulfide (CS2), has been investigated. 172 nm (7.2 eV) VUV photons from Xe2* excimers in a microcavity plasma lamp irradiated free-standing liquid droplets on Si substrate in each a nitrogen environment and an atmospheric air environment. Selective and rapid dissociation of CS2 into C-C, C-S or C-O-S based fragments was observed in the different gas environments during the reaction. Thin-layered polymeric microdeposites have been identified by characterization with a Scanning electron microscope (SEM), Energy dispersive x-ray spectroscopy (EDX), Raman spectroscopy and X-ray photoelectron spectroscopy (XPS). This novel photo-process from the flat VUV microplasma lamp introduces another pathway of low-temperature organic (or synthetic) conversion for large area deposition. The in-situ, selective conversion of various organic precursors can be potentially used in optoelectronics and nanotechnology applications.

Molecular Insights of Carbon Nanodot Formation and Their Two-Photon Emission Properties

The structure formation of carbon nanodots (C-dots) prepared from three different organic precursors is discussed at the molecular level. During microwave synthesis, organic chromophores associated with C-dot structures are formed that exhibit distinct optical features. We have elucidated the molecular structure of these fluorophores and investigated their optical properties with and without the C-dots. The emergence of two-photon emission was observed and correlated with the hybridization state of the carbon atoms within the C-dot as well as the formation of the fluorophores. Varying contents of sp2 and sp3 hybridization in different C-dots also affects their one-photon and two-photon emission characteristics. Understanding the molecular structure of the <br>carbon nanocore and the organic fluorophores formed in C-dots would enable rational design of C-dots with improved optical features, which would be of great relevance for their applications, for example, in bioimaging. <br>

Molecular Insights of Carbon Nanodot Formation and Their Two-Photon Emission Properties

The structure formation of carbon nanodots (C-dots) prepared from three different organic precursors is discussed at the molecular level. During microwave synthesis, organic chromophores associated with C-dot structures are formed that exhibit distinct optical features. We have elucidated the molecular structure of these fluorophores and investigated their optical properties with and without the C-dots. The emergence of two-photon emission was observed and correlated with the hybridization state of the carbon atoms within the C-dot as well as the formation of the fluorophores. Varying contents of sp2 and sp3 hybridization in different C-dots also affects their one-photon and two-photon emission characteristics. Understanding the molecular structure of the <br>carbon nanocore and the organic fluorophores formed in C-dots would enable rational design of C-dots with improved optical features, which would be of great relevance for their applications, for example, in bioimaging. <br>

Environmentally Persistent Free Radicals as Sources of POPs

Environmentally persistent free radicals (EPFRs) are a new class organic pollutant sharing some of the attributes of persistent organic pollutants (POPs). This opinion/short review aims to describe the properties of EPFRs that merit their recognition as an additional and potentially significant source of POPs. EPFRs are ubiquitous in diverse environments because of multiple factors: (1) organic precursors from anthropogenic, biogenic, and other natural emission sources are abundant; multiple mechanisms in PM and soils form (2) EPFRs; and (3) EPFRs are stable and persist for a long time, thereby, accumulate in the environment and potentially transported long range. The hazards of EPFRs arise from their ability to induce oxidative stress and the formation of hazardous byproducts. EPFRs are ultimately deactivated by reactive processes, yielding molecular recombination byproducts that are structurally similar to those classified as POPs. It is plausible that EPFRs may form POPs in vivo in organisms; therefore, they are potential additional sources of exogenous POPs. Understanding the formation of EPFRs and extensive investigation of the pollutants generated from their recombination will add to the growing body of knowledge on their environmental and health hazards.