Rapid screening for anthocyanins and anthocyanin dimers in crude grape extracts by high performance liquid chromatography coupled with diode array detection and tandem mass spectrometry

A rapid and efficient method using high performance liquid chromatography coupled with diode array detection and tandem mass spectrometry (HPLC-DAD–MS/MS) for fast screening large numbers of anthocyanins and anthocyanin dimers in different grape skin extracts, without further sample clean-up procedures, was developed. A good separation of most detected anthocyanins was achieved in a run time of 15 min. Identification of anthocyanin pigments required a combination of several information: UV–vis spectra, MS and MS/MS spectra, and elution pattern. Many compounds have been here detected for the first time and their structures tentatively elucidated.     

A new silicon lewis acid for highly enantioselective mannich reactions of aliphatic ketone-derived hydrazones

The first general method for the highly enantioselective Mannich reaction of aliphatic ketimines is reported. A new, second generation chiral silane Lewis acid has been developed that promotes the reaction between ketone-derived hydrazones and silyl ketene acetals, providing the beta,beta-disubstituted beta-amino esters with good enantioselectivity even for the hydrazone derived from 2-butanone (methyl vs ethyl, 91% ee). Several examples are provided, including a reaction with a substituted (propanoate-derived) silyl ketene acetal.     

Working towards the development of innovative ultrasound equipment for the extraction of virgin olive oil

Malaxation has been recognized as one of the most critical points in the mechanical extraction process for virgin olive oil (VOO). It is a low and continuous kneading of olive paste at a carefully monitored temperature. Through this essential technological operation the small droplets of the oil formed during the milling merge into large drops that can be easily separated with a decanter centrifuge. During this technological phase, a complex and necessary bioprocess takes place in order to determine the quality and composition of the final product. The malaxer is a heat exchanger characterized by a low overall heat transfer coefficient because the ratio of surface area to volume is disadvantageous, so it is important to find an innovative technology to improve heat-exchange. As matter of fact, the malaxing step is the only discontinuous phase in a continuous extraction process. In the next future, the essential challenge of VOO industrial plant manufacturing sector is to design and build advanced machines in order to transform the discontinuous malaxing step in a continuous phase and improve the working capacity of the industrial plants. In order to reduce the malaxing time enhancing the quality of the product, two ultrasound-assisted virgin olive oil extraction processes were tested against the traditional method. The sonication treatment was applied on olives submerged in a water bath (before the crushing) and on olive paste (after the crushing). The ultrasound technology provides a reduction of the malaxing duration improving VOO yields and its minor compounds content. Better extractibility and higher minor compounds contents were obtained by sonicating the olives submerged in a water bath than olive paste. After experimental trials the results were employed to suggest innovative scaling up solutions of the process and new applications of ultrasounds in the VOO industry.     

Dirac wave equation in the de Sitter universe

We present and discuss the Dirac wave equation in the de Sitter universe. This equation is obtained by factoring the second-order Casimir invariant operator associated to the Fantappié-de Sitter group.     

Stable aqueous nanoparticle film assemblies with covalent and charged polymer linking networks

The construction of highly stable and efficiently assembled multilayer films of purely water soluble gold nanoparticles is reported. Citrate-stabilized nanoparticles (CS-NPs) of average core diameter of 10 nm are used as templates for stabilization-based exchange reactions with thioctic acid to form more robust aqueous NPs that can be assembled into multilayer films. The thioctic acid stabilized nanoparticles (TAS-NPs) are networked via covalent and electrostatic linking systems, employing dithiols and the cationic polymer poly(L-lysine), respectively. Multilayer films of up to 150 nm in thickness are successfully grown at biological pH with no observable degradation of the NPs within the film. The characteristic surface plasmon band, an optical feature of certain NP film assemblies that can be used to report the local environment and core spacing within the film, is preserved. Growth dynamics and film stability in solution and in the air are examined, with poly(L-lysine) linked films showing no evidence of aggregation for at least 50 days. We believe these films represent a pivotal step toward exploring the potential of aqueous NP film assemblies as a sensing apparatus.     

Kinetic resolution of protected alpha-amino acid derivatives by a chiral O-nucleophilic acyl transfer catalyst

The kinetic resolution of alpha-trifluoroacetamido N-acyl oxazolidinethiones using 5-10% of the chiral, nonracemic O-nucleophilic acyl transfer catalyst 2 is described. A variety of substrates participate in this reaction in excellent yields, with s-factors ranging from 20 to 86.