On the normal subgroup lattice of a hypercentral p-group

We describe all hypercentral p-groups G whose lattice of normal subgroups n(G) is isomorphic to n(H) for a group H with hypercenwal derived subgroup and H not a pgroup.     

The Vatican museum and the organic natural products. The Raphael’s frescoes and the “Last Judgment” by Nicolò and Giovanni

Abstract

In the second half of the 90s, alongside the restoration works of the Quattrocentisti (fifteenth century painters) in the Sistine Chapel, it also carried out the restoration of the frescoes of the Stanze di Raffaello. The results of scientific investigations conducted by the Scientific Research Laboratory of the Vatican Museums, previously presented in some assays of study, are summarised and presented in this letter to the Editor for the special issue of Natural Product Research: Natural Products in Cultural Heritage.     

L-tryptophan transport through a hydrophobic liquid membrane using AOT micelles: dynamics of the process as revealed by small angle X-ray scattering

Hydrophobic liquid membranes have a high technological potential in many fields of separation science. The dynamics of these systems is very complex and still not fully understood. In this work we studied the effect of the incorporation of cationic and anionic L-tryptophan at pH 1.8 and 10.0, respectively, in Aerosol-OT reverse micelles performing small angle X-ray scattering experiments. The use of a synchrotron radiation source allowed efficient in situ data acquisition. Several insights on L-tryptophan transport dynamics through hydrophobic membranes containing AOT could be obtained from these SAXS experiments, such as amino acid site localization and changes in the reverse micelle sizes.     

Computational DFT investigation of vicinal amide group anchimeric assistance in ether cleavage

Density functional theory (DFT) computations in solvent have been used to investigate the mechanism of anchimeric assistance (by a vicinal amide group) in the acid-induced ether cleavage. The calculations were carried out at the B3LYP/6-31G* level of theory via full geometry optimizations within the IEF-PCM continuum solvent model. Two different mechanisms have been investigated here that were previously hypothesized for the rate-determining step of this process: the first (mechanism A1) involves a protonated amide and an ethereal oxygen as the nucleophile, while the second (mechanism A2) involves protonation of the ethereal oxygen followed by a nucleophilic attack of the amide. Computations clearly show that the second (involving protonation of the less basic site) is the most favorite route and leads to the formation of an oxazolidinic intermediate that triggers ether hydrolysis. Results are produced that are in excellent agreement with the experiments, and a rationale for them is provided, which represents a general interpretative basis for similar anchimerically assisted processes, such as the ones characterizing the glycosidic activity of two very important classes of enzymes: beta-hexosaminidases and O-GlcNAcases.     

Synthesis of 2-diphenylphosphinoyl-3,5-(diaryl)-3,4-dihydro-2H-thiopyrans by the reaction of a bis[(diphenylphosphinoyl)methyl]sulfide with chalcones

The NaH-promoted tandem Michael addition/intramolecular Horner-Wittig reaction of bis(diphenylphosphinoylmethyl)sulfide with chalcones afforded 3,4-dihydro-2H-thiopyrans 3a-l in 78-88% yield.     

XPS and AFM characterization of the enzyme glucose oxidase immobilized on SiO(2) surfaces

A process to immobilize the enzyme glucose oxidase on SiO2 surfaces for the realization of integrated microbiosensors was developed. The sample characterization was performed by monitoring, step by step, oxide activation, silanization, linker molecule (glutaraldehyde) deposition, and enzyme immobilization by means of XPS, AFM, and contact angle measurements. The control of the environment during the procedure, to prevent silane polymerization, and the use of oxide activation to obtain a uniform enzyme layer are issues of crucial importance. The correct protocol application gives a uniform layer of the linker molecule and the maximum sample surface coverage. This result is fundamental for maximizing the enzyme bonding sites on the sample surface and achieving the maximum surface coverage. Thin SiO2 layers thermally grown on a Si substrate were used. The XPS Si 2p signal of the substrate was monitored during immobilization. Such a signal is not completely shielded by the thin oxide layer and it is fully suppressed after the completion of the whole protocol. A power spectral density analysis on the AFM measurements showed the crucial role of both the oxide activation and the intermediate steps (silanization and linker molecule deposition) to obtain uniform immobilized enzyme coverage. Finally, enzymatic activity measurements confirmed the suitability of the optimized protocol.     

Uncertainty evaluation for the quantification of low masses of benzo[a]pyrene: Comparison between the Law of Propagation of Uncertainty and the Monte Carlo method

A proper evaluation of the uncertainty associated to the quantification of micropollutants in the environment, like Polycyclic Aromatic Hydrocarbons (PAHs), is crucial for the reliability of the measurement results. The present work describes a comparison between the uncertainty evaluation carried out according to the GUM uncertainty framework and the Monte Carlo (MC) method. This comparison was carried out starting from real data sets obtained from the quantification of benzo[a]pyrene (BaP), spiked on filters commonly used for airborne particulate matter sampling. BaP was chosen as target analyte as it is listed in the current European legislation as marker of the carcinogenic risk for the whole class of PAHs.     

High-throughput mutational screening for beta-thalassemia by single-nucleotide extension

In this work a high-throughput method based on the single-nucleotide extension (SNE) reaction and multicolour detection in a DNA sequencer was developed to screen for eight mutations in the human beta-globin gene: IVSI.110, cd39, IVSI.1, IVSI.6, IVSII.745, HbC, HbS and cd6. The method has been validated on a large number of samples for the two most common mutations causing beta-thalassemia in the Mediterranean area (IVSI.110 and cd39). The development of a high-throughput, fast and reliable method to assay beta-thalassemia mutations represents a significant improvement in molecular diagnosis of this disease. The multicolour detection and the use of multiple injections further enhances the throughput of mutational screening by the DNA sequencer and facilitates automated genotyping for routine molecular diagnostics.