UNUSUAL SULFUR AND SELENIUM AMINO ACIDS

Presentation of synthetic methods for novel, unnatural sulfur and selenium containing amino acid

Quantification of gliadin levels to the picogram level by flow cytometry

Celiac disease is a widely prevalent enteropathy caused by intolerance to gliadin, one of the gluten proteins. We developed two methods for the analysis of gliadin levels. Both methods use flow cytometry and rat antibodies against a 16-residue peptide of gliadin. The peptide is common to the alpha-, beta-, gamma-, and omega-gliadins

Novel sulfur and selenium containing bis-α-amino acids from 4-hydroxyproline

The synthesis of new substituted prolines carrying at C-4 a second α-amino acid residue is reported. The amino acid, l-cysteine or l-selenocysteine, is linked to the proline ring through the sulfur or the selenium atom, respectively. The products were prepared with different stereochemistry at C-4, in few and clean high-yielding steps, with suitable protections for solid phase applications. The introduction of both sulfur and selenium atoms at C-4 of the proline ring seems to enhance significantly the cis geometry at the prolyl amide bond

A practical route to β 2,3 -amino acids with alkyl side chains

Enantiopure N(Boc)-β 3 -amino nitriles, valuable synthetic intermediates in the multistep homologation of α-amino acids, were alkylated using n-BuLi as base. Alkylations afforded easily separable, almost equimolecular mixtures of diastereomeric N(Boc)-protected syn and anti β 2,3 -amino nitriles. Suitable manipulations of both cyano and amino groups eventually led to enantiopure N- and/or C-protected β 2,3 -amino acids. For example, methanolysis using conc. HCl gas in MeOH, provides C-protected β 2,3 amino acids in excellent yields. This methodology is applied to the synthesis of a series N(Boc)-β 2,3 -dialkyl amino nitriles derived from L-phenylalanine, D-phenylalanine, L-valine and one C-protected β 2,3 amino acid. We demonstrate an efficient procedure for the preparation of anti and syn β 2,3 -amino acids with alkyl side chains, from α-amino acids in reasonable yields

Optical and electrical characterizations of graphene nanoplatelet coatings on low density polyethylene

Coatings of graphene nanoplatelets (GNPs) were deposited on a low density polyethylene (LDPE) substrate by a micromechanical method based on rubbing graphite platelets against the surface of the polymer. Transmission electron microscopy measurements reveal that the coatings were composed of nanoplatelets containing 13–30 graphene layers. Thermal gravimetric analysis shows that the investigated GNP coatings on LDPE (GNP/LDPE) samples are thermally stable up to 250C. Optical spectra of these samples, compared to those of pristine LDPE in the ultraviolet- visible-near-infrared range, indicate an increase in both reflectance and absorptance. On the other hand, the coating is able to markedly improve the surface conductivity of the polymeric substrate, indeed in the case of electrical contacts in the coplanar configuration (1 cm long and spaced 1 mm), the resistance of LDPE is 1015X, while that of GNP/LDPE is 670X. Electrical measurements under white light illumination point out a decrease in the conductance and a linear behavior of the photoconductance as a function of the optical power density. GNP/LDPE materials can be used for their optical, electrical, thermal, and flexibility properties in large area plastic electronics and optoelectronics. Published by the AV

The Comet Interceptor Mission

Here we describe the novel, multi-point Comet Interceptor mission. It is dedicated to the exploration of a little-processed long-period comet, possibly entering the inner Solar System for the first time, or to encounter an interstellar object originating at another star. The objectives of the mission are to address the following questions: What are the surface composition, shape, morphology, and structure of the target object? What is the composition of the gas and dust in the coma, its connection to the nucleus, and the nature of its interaction with the solar wind? The mission was proposed to the European Space Agency in 2018, and formally adopted by the agency in June 2022, for launch in 2029 together with the Ariel mission. Comet Interceptor will take advantage of the opportunity presented by ESA's F-Class call for fast, flexible, low-cost missions to which it was proposed. The call required a launch to a halo orbit around the Sun-Earth L2 point. The mission can take advantage of this placement to wait for the discovery of a suitable comet reachable with its minimum ΔV capability of 600 ms-1. Comet Interceptor will be unique in encountering and studying, at a nominal closest approach distance of 1000 km, a comet that represents a near-pristine sample of material from the formation of the Solar System. It will also add a capability that no previous cometary mission has had, which is to deploy two sub-probes - B1, provided by the Japanese space agency, JAXA, and B2 - that will follow different trajectories through the coma. While the main probe passes at a nominal 1000 km distance, probes B1 and B2 will follow different chords through the coma at distances of 850 km and 400 km, respectively. The result will be unique, simultaneous, spatially resolved information of the 3-dimensional properties of the target comet and its interaction with the space environment. We present the mission's science background leading to these objectives, as well as an overview of the scientific instruments, mission design, and schedule

The Comet Interceptor Mission

Here we describe the novel, multi-point Comet Interceptor mission. It is dedicated to the exploration of a little-processed long-period comet, possibly entering the inner Solar System for the first time, or to encounter an interstellar object originating at another star. The objectives of the mission are to address the following questions: What are the surface composition, shape, morphology, and structure of the target object? What is the composition of the gas and dust in the coma, its connection to the nucleus, and the nature of its interaction with the solar wind? The mission was proposed to the European Space Agency in 2018, and formally adopted by the agency in June 2022, for launch in 2029 together with the Ariel mission. Comet Interceptor will take advantage of the opportunity presented by ESA’s F-Class call for fast, flexible, low-cost missions to which it was proposed. The call required a launch to a halo orbit around the Sun-Earth L2 point. The mission can take advantage of this placement to wait for the discovery of a suitable comet reachable with its minimum ΔV capability of 600 ms−1. Comet Interceptor will be unique in encountering and studying, at a nominal closest approach distance of 1000 km, a comet that represents a near-pristine sample of material from the formation of the Solar System. It will also add a capability that no previous cometary mission has had, which is to deploy two sub-probes – B1, provided by the Japanese space agency, JAXA, and B2 – that will follow different trajectories through the coma. While the main probe passes at a nominal 1000 km distance, probes B1 and B2 will follow different chords through the coma at distances of 850 km and 400 km, respectively. The result will be unique, simultaneous, spatially resolved information of the 3-dimensional properties of the target comet and its interaction with the space environment. We present the mission’s science background leading to these objectives, as well as an overview of the scientific instruments, mission design, and schedule

Teorie e pratiche della conservazione museale del secondo dopoguerra - un caso campano: Ezio Bruno De Felice

Teorie e pratiche della conservazione museale del secondo dopoguerra - un caso campano: Ezio Bruno De Felic

Enantiopure b3-amino acids-2,2-d2 via homologation of proteinogenic a-amino acids

A procedure for the synthesis of enantiopure β3-amino acids from proteinogenic α-amino acids, developed by our group a few years ago, has been modified to enable the production of C-2 fully deuterated, C-protected β3-amino acids and, even more important, the synthesis of valuable deuterium labelled N(Boc)-protected chiral synthons, such as 2-aminoalcohols, 2-aminoiodides, and β3-amino nitriles

Protection and Activation of Hydroxycinnamic Acids in Water

Hydroxycinnamic acids such as p-coumaric, ferulic, sinapic and caffeic acids were protected as carbonates and activated as mixed carbonic anhydrides in water at RT by adding a base and isobutyl chloroformate. These anhydrides were used for amine and C-protected α-amino acid acylation to give O-carbonate protected phenolic amides. Acylation of free α-amino acids was performed in acetone-water in high yields producing the O- carbonate protected N-hydroxycinnamoyl-α-amino acids. Pure derivatives were obtained in many cases directly by crystallization. Free phenolic compounds were rapidly obtained by carbonate deprotection with piperidine. The method offers a novel route for amide bond formation in water and the direct functionalization of hydroxycinnamic acid families with free α- amino acids, providing a facile preparation of precious natural bioactive derivatives