Characterisation of alumina-supported vanadium oxide catalysts by kinetic analysis of H2-TPR data

Alumina-supported vanadium oxide catalysts with vanadium contents of 2, 5 and 11 wt.% were prepared by incipient wetness impregnation and characterised by XRD, Raman spectroscopy and H₂-TPR. The catalysts with the low vanadium contents contained vanadium mainly in the well-dispersed phase, but the catalyst with the highest vanadium content contained also some crystalline AlVO₄ according to XRD and Raman spectroscopic results. The reduction kinetics of the vanadium catalysts was modelled based on the hydrogen consumption during the TPR. The reduction kinetics could be described with a single-reducible-site random nucleation model for the catalyst containing the lowest amount of vanadium. The reduction kinetic models for the other catalysts required a combination of multiple processes to describe the experiments properly. In the catalyst with 5 wt.% V, a part of vanadium species possibly reduces as a homogeneous random nucleation process, but topochemical reduction by nuclei growth also takes place. In the catalyst with 11 wt.% V, reduction by nuclei growth seems to be the predominant reduction mechanism. The characterisation of the reduced catalysts by XRD and during reduction by Raman spectroscopy enabled the identification of the features of the TPR profiles.     

Organic Solvent Tolerance of Retro-Friedel–Crafts Hydrolases

Retro-Friedel–Crafts hydrolases are co-factor independent enzymes with unusual reactivity and selectivity. These unique hydrolases are scarcely studied for biocatalytical applications in organic chemistry yet, although many other hydrolytic enzymes (e.g. lipases) are commonly applied as catalysts. Two Friedel–Crafts hydrolases were selected, namely 2,6-diacetylphloroglucinol hydrolase (PhlG) from Pseudomonas fluorescens and phloretin hydrolase from Eubacterium ramulus (Phy), to test the suitability of these enzymes in synthetic applications. The activity and stability of PhlG and Phy as lyophilized cells or lyophilized crude extracts were investigated in the presence of organic co-solvents. It was shown, that by careful selection of the co-solvent the enzymes catalyse C–C hydrolysis in a buffer solvent mixture with improved conversions at 50 mM substrate concentration. However, attempts to catalyze C–C-bond formation in organic solvents were unsuccessful.     

Systematic Structure–Activity Study on Potential Chaperone Lead Compounds for Acid α‐Glucosidase

Acid α‐glucosidase (GAA) is a lysosomal enzyme and a pharmacological target for Pompe disease, an inherited lysosomal storage disorder (LSD). An emerging treatment for LSDs is the use of pharmacological chaperones, small molecules that enhance total cellular activity of the target lysosomal protein. We have systematically studied thirteen inhibitors, which provide good lead compounds for the development of GAA chaperones. We have verified binding on GAA at low and neutral pH, mapping the range of pH during transport to lysosomes. These ligands inhibit GAA competitively and reversibly, and a few of the compounds show higher molecular stabilisation capacity than would be expected from their binding affinity. These molecules also increase lysosomal localisation of GAA variants in cells. In order to understand the specific molecular mechanism of the interactions, we docked the compounds to a homology model of the human GAA. Three factors contribute to the tightness of binding. Firstly, well‐positioned hydroxy groups are essential to orient the ligand and make the binding specific. Secondly, the open nature of the GAA active site allows both large and small ligands to bind. The third and most important binding determinant is the positive charge on the ligand, which is neutralised by Asp 518 or Asp 616 on GAA. Our study creates a firm basis for the design of drugs to treat Pompe disease, as it provides a comparable study of the ligand properties. Our analysis suggests a useful drug design framework for specific pharmacological chaperones for human GAA.     

Rice husk ash as an adsorbent for purifying biodiesel from waste frying oil

The goal of this work is to study the purification of biodiesel from waste frying oil (WFO) using rice husk ash (RHA) at concentrations of 1%, 2%, 3%, 4% and 5% (w/w) and compare it with two other different purification methods, the traditional acid solution (1% aqueous H₃PO₄) and with the commercial adsorbent Magnesol® 1% (w/w). The structure and composition of the RHA were studied to better understand its properties as an adsorbent. In a concentration of 4%, the RHA showed excellent results for removal impurities from biodiesel. The high concentration of silica in its composition and the presence of meso and macropores can explain its high capacity of adsorption. Thus, the RHA, that is a byproduct of the rice processing, can appear as an alternative material for biodiesel purification.     

Novel two-step synthesis of gold nanoparticles capped with bile acid conjugates

Bile acids and their conjugates are physiologically important molecules. Syntheses and structure elucidation combined with investigation of properties and applications of bile acids and their derivatives are of academic interest. The concept of using bile acids and their conjugates in nanoscience is a novel idea, which opens up fascinating prospects. In this article, an easy and simple route for obtaining N-lithocholyl-l-(cysteine ethyl ester) (3), capable of effectively capping and stabilizing metal nanoparticles, is described. The whole synthetic route needs only two steps giving a moderate to good yield. The gold NPs are characterized by elemental analysis, UV spectroscopy, and TEM. Additionally, ¹³C CP/MAS NMR studies for different ligand/Au ratios have been performed.     

Correction to: 6G and the UN SDGs: Where is the Connection?

Wireless Personal Communications - With the evolution of smart grid system (SGS), many issues associated with traditional grid network, i.e., power system security, monitoring and control, energy...     

Distribution of microbes in supercritical CO2 extraction of sea buckthorn (Hippophaë rhamnoides) oils

The distribution of vegetative microbial cells and their spores in a supercritical CO₂ extraction process was studied. The seed and flesh/skin fractions of the press residue of sea buckthorn berries (Hippophaë rhamnoides) from a juice factory were used as raw materials. A pilot-scale extraction plant was operated at 30?MPa at temperatures of 40 and 60°C. The number of yeasts, moulds and bacteria in the pulp/skin fraction, in the extraction residues, in the extracted oils as well as in the water phases separated from the extracted oils was estimated by the spread plate technique. The microbial content of the flesh/skin material was increased in some extractions by the addition of bacterial spores. In general, the extraction process led to a decrease in the bacterial count of the extracted material, whereas no microbial growth was detected in the oils extracted or in the water phases separated from them. Neither yeasts nor moulds were found in any samples after the extraction process. The microbial status of seed oil and flesh/skin oil obtained by industrial-scale CO₂ extraction at 40°C and at 30?MPa before and after gelatine encapsulation remained unchanged. This proves that supercritical CO₂ can be used to manufacture edible oil products free of living micro-organisms and their spores.