Systematic optimization of the analysis of wine bouquet components by solid-phase microextraction

The extraction, identification, and quantification of wine aroma compounds are preliminary steps required for further investigation of wine quality, i.e. determination of the varieties of grapes used, the production process, and the origin and age of the wine. This paper deals with the optimization of solid-phase microextraction for the determination of compounds which produce wine bouquet. Optimum operating conditions have been determined to obtain high reproducibility at low cost and with low time-consumption. Several factors influencing the equilibrium of the aroma compounds between the sample and the fiber must be taken into account, including length of contact time between the two phases involved, speed of agitation of the sample, the matrix in which the process takes place, and, furthermore, the place, duration, and temperature of desorption in the injector of the chromatograph.     

Bacterial production of PHA from lactose and cheese whey permeate

Due to the large availability of agro-industry wastes containing potentially exploitable substrates, such as whey from dairy industry, a study on the bacterial conversion of lactose and whey permeate to poly(β-hydroxyalkanoate) (PHA) was undertaken. A first approach was carried out on culture collection strains. Among a number of strains tested, Hydrogenophaga pseudoflava DSM 1034 and Sinorhizobium meliloti 41 were found to grow on lactose and produce PHA. These findings suggested to investigate among a wider range of microorganisms by directly isolating new strains from soil. A number of soil bacteria were first isolated on a minimal medium containing lactose as unique carbon source and PHA-accumulating traits were then investigated. Three isolates, identified by 16S rDNA sequence analysis as Sinorhizobium sp., Bacillus megaterium and Bacillus sp., were selected for their efficient growth and PHA production using lactose as carbon source. The same strains were also tested for their ability to accumulate PHA by direct fermentation of whey and whey permeate. Our results suggest that production of the polymer from cheese whey or whey permeate may be possible, although further research is needed to determine whether these microorganisms have the potential for commercial production of such biodegradable polymers.     

29Si and 27Al MAS NMR assessment of the C-(A-) S–H nanomolecular structure of Ultra-High-Performance Concrete (UHPC) modified with pyrogenic oxides

Ultra-High Performance Concrete (UHPC) that contains pyrogenic oxides (Pox) and has been heat-cured with microwave energy reaches as high as 420 MPa after 1 day. The influence of microwave curing on the strength gain is much more pronounced in UHPC than in normal concrete. ²⁹Si and ²⁷Al MAS NMR nanomolecular structure investigation of Ultra-High-Performance Concrete (UHPC) modified with nanoscale pozzolans (pyrogenic oxides) reveals significant differences from other concrete types that may explain such high early strength. There is an increase in polymerization degree of C-(A) S–H (C–S–H containing Al) phase of the UHPC modified with pyrogenic oxides, followed by a trend of substitution of silicon atoms on the Q? sites of C–S–H (calcium-silicate-hydrates) through aluminum atoms. The mean chain length (MCL) and degree of connectivity (Dc) are the highest for pyrogenic oxides containing UHPC that have been cured with microwave energy. The increase of polymerization degree is more pronounced for alumina-based pyrogenic oxide containing UHPC.     

Changes in the spectroelectrochemical properties of copper(II) hexacyanoferrate(III) during electrochemical insertion of alkaline ions

Journal of Solid State Electrochemistry - In this work, the influence of the electrochemical insertion of different alkali ions, e.g., lithium, sodium, and potassium, on the electrochromic...     

Exploding Chemical Gardens: A Phase‐Change Clock Reaction

Chemical gardens and clock reactions are two of the best‐known demonstration reactions in chemistry. Until now these have been separate categories. We have discovered that a chemical garden confined to two dimensions is a clock reaction involving a phase change, so that after a reproducible and controllable induction period it explodes.     

Groups whose subgroups have small automizers

IfH is a subgroup of a groupG, theautomizer ofH inG is the group of all automorphisms ofH induced by elements of its normalizerN _G (H). the subgroupH is said to havesmall automizer ifAut _G (H)=Inn(H), i.e. ifN _G (H)=HC _G (H). This article is devoted to the study of groups for which many subgroups have small automizer. In Memoriam Valeria Fedri R. Brandl wishes to express his sincerest thanks for the warm hospitality offered by the Department of Mathematics of the University of Napoli “Federico II” for the time of writing this paper.     

Bioprospecting the Antibiofilm and Antimicrobial Activity of Soil and Insect Gut Bacteria

Antimicrobial resistance is a growing concern in public health and current research shows an important role for bacterial biofilms in recurrent or chronic infections. New strategies, therefore, are necessary to overcome antimicrobial resistance, through the development of new therapies that could alter or inhibit biofilm formation. In this sense, antibiofilm natural products are very promising. In this work, a bioprospection of antimicrobial and antibiofilm extracts from Uruguayan soil bacteria and insect gut bacteria was carried out. Extracts from extracellular broths were tested for their ability to inhibit planktonic cell growth and biofilm formation. Genomic analysis of Bacillus cereus ILBB55 was carried out. All extracts were able to inhibit the growth of, at least, one microorganism and several extracts showed MICs lower than 500 µg mL⁻¹ against microorganisms of clinical relevance (Staphylococcus aureus, Pseudomonas aeruginosa, and Enterobacter cloacae). Among the extracts evaluated for biofilm inhibition only ILBB55, from B. cereus, was able to inhibit, S. aureus (99%) and P. aeruginosa (62%) biofilms. Genomic analysis of this strain showed gene clusters similar to other clusters that code for known antimicrobial compounds. Our study revealed that extracts from soil bacteria and insect gut bacteria, especially from B. cereus ILBB55, could be potential candidates for drug discovery to treat infectious diseases and inhibit S. aureus and P. aeruginosa biofilms.     

The Photochemistry of (Diene)(hydro)[tris(3,5-dimethylpyrazolyl)borato]rhodium Complexes,Preliminary Communication

The photochemical rearrangement of [Rh(η⁴-1,5-cod)Tp^Me2](Tp^Me2=hydrotris(3,5-dimethylpyrazolyl)borato, 1,5-cod=cycloocta-1,5-diene) to the new compound [Rh(η⁴-1,3-cod)Tp^Me2] ( 2 ) is described. The characterization of 2 was carried out using ¹H-, ¹³C-, and ¹⁰³Rh-HMQC-NMR spectroscopy. Photolysis of 2 is a versatile entry point into the organometallic chemistry of the {RhTp^Me2} fragment as it can be used to produce a) hydrido-carbonyl ([Rh(CO)H₂Tp^Me2]), b) hydrido-phenyl-phosphite ([RhH(Ph)(P(OMe)₃)Tp^Me2]), and c) ethoxide-hydrido-phosphite ([RhH(OEt)(P(OMe)₃)Tp^Me2]) complexes.