On peptide bond formation from protonated glycine dimers in the gas phase: computational insight into the role of protonation.

Peptide bond formation from the pure protonated glycine dimer, H(Gly), and from the mixed protonated glycine-diglycine dimer, HGly(Gly), was recently found experimentally to occur in gas-phase experiments in the absence of any catalyst and especially under anhydrous conditions [, 2023, , 775]. In this contribution we further examine the conditions of such unimolecular reactions by means of density-functional theory calculations at the DFT/M06 2X/6-311G++(2df,p) level, focusing in particular on the role played by the protonation site. Two pathways, stepwise and concerted, are identified for the pure protonated dimer, and six pathways are examined for the mixed dimer.

Reasons for cigarette and tobacco product use, dual use, and poly use among university students.

Introduction: Tobacco use remains a significant public health issue worldwide, causing over 7 million deaths annually. Polytobacco use has become a common phenomenon. This study aims to analyze reasons for cigarette and tobacco product use, dual use and poly use among university students by sex, in China and Cyprus, selected owing to their still high consumption rates.

FLIP: a novel method for patient-specific dose quantification in circulating blood in large vessels during proton or photon external beam radiotherapy treatments.

To provide a novel and personalized method (and Irradiation Personalized) using patient-specific circulating blood flows and individualized time-dependent irradiation distributions, to quantify the dose delivered to blood in large vessels during proton or photon external beam radiotherapy.Patient-specific data were obtained from ten cancer patients undergoing radiotherapy, including the blood velocity field in large vessels and the temporal irradiation scheme using photons or protons. The large vessels and the corresponding blood flow velocities are obtained from phase-contrast MRI sequences.