An asymptomatic detachment of the appendix evolved to giant abscess and complete colliquative necrosis: pivotal role of computed tomography in patient management

Acute appendicitis (AA) is one of the most common causes of acute abdominal pain and it generally affects young males in the second or third decade of their life. Due to its often insidious presentations, the diagnosis is challenging and, if delayed, can lead to life-threatening complications. This report describes a rare case of an almost asymptomatic complicated appendicitis caused by an appendicolith followed by spontaneous detachment of the vermiform appendix and its complete colliquative necrosis with abscess formation. Thus far this is the first case of spontaneous appendix avulsion in an adult where the appendix is entirely colliquated into an abscess

Electron and ion spectroscopy of Azobenzene in the valence and core shells

Azobenzene is a prototype and building block of a class of molecules of extreme technological interest as molecularphoto-switches. We present a joint experimental and theoretical study of its response to irradiation with light across theUV to X-ray spectrum. The study of valence and inner shell photo-ionization and excitation processes, combined withmeasurement of valence photoelectron-photoion coincidence (PEPICO) and of mass spectra across the core thresholdsprovides a detailed insight onto the site- and state-selected photo-induced processes. Photo-ionization and excita-tion measurements are interpreted via the multi-configurational restricted active space self-consistent field (RASSCF)method corrected by second order perturbation theory (RASPT2). Using static modelling, we demonstrate that thecarbon and nitrogen K edges of Azobenzene are suitable candidates for exploring its photoinduced dynamics thanks tothe transient signals appearing in background-free regions of the NEXAFS and XP

Radiation Damage Mechanisms of Chemotherapeutically Active Nitroimidazole Derived Compounds

Photoionization mass spectrometry, photoelectron-photoion coincidence spectroscopic technique, and computational methods have been combined to investigate the fragmentation of two nitroimidazole derived compounds: the metronidazole and misonidazole. These molecules are used in radiotherapy thanks to their capability to sensitize hypoxic tumor cells to radiation by “mimicking” the effects of the presence of oxygen as a damaging agent. Previous investigations of the fragmentation patterns of the nitroimidazole isomers (Bolognesi et al., 2016; Cartoni et al., 2018) have shown their capacity to produce reactive molecular species such as nitric oxide, carbon monoxide or hydrogen cyanide, and their potential impact on the biological system. The results of the present work suggest that different mechanisms are active for the more complex metronidazole and misonidazole molecules. The release of nitric oxide is hampered by the efficient formation of nitrous acid or nitrogen dioxide. Although both metronidazole and misonidazole contain imidazole ring in the backbone, the side branches of these molecules lead to very different bonding mechanisms and properties

VUV Photofragmentation of CH2I2: The [CH2I–I]•+ iso-diiodomethane intermediate in the I-loss channel from [CH2I2]•+

Diiodomethane is an important halocarbon responsible for several atmospheric processes like ozone depletion and aerosol particle formation. Despite this, the thermochemical data and a detailed analysis of the pathways for the decomposition of this halomethane and its molecular ion [CH2I2]•+ are scarce. In this paper an investigation of the photodissociation dynamics of the CH2I2 molecule focused on the I-loss channel by the photoelectron–photoion coincidence (PEPICO) technique and computational methods is reported. The experimental results show that upon VUV irradiation the dissociation of the lower electronic ionic states of diiodomethane leads only to the CH2I+ ion and the I atom. The theoretical calculations point out that isomerization of [CH2I2]•+ into iso-diiodomethane [CH2I–I]•+ may play an important role in the emission of iodine atom as compared to direct C–I bond breaking

Modeling Laser-Induced Plasma Expansion Under Equilibrium Conditions

A theoretical investigation of the expansion of the plasma, produced by a nanosecond laser pulse hitting a titanium metallic target, has been carried out. The study is oriented to understand the interaction of the plasma plume with the surrounding gas (air) not only from the fluid dynamic point of view, but also considering the effects of chemical reactions. To this purpose, a 2-D solver of the Euler equations has been developed and self-consistently coupled with the local thermodynamic equilibrium calculation. The results show the plasma confinement due to the ambient gas and the appearance of metallic oxides in proximity of the plume border

A joint theoretical and experimental study on diiodomethane: Ions and neutrals in the gas phase

The chemical physics of halomethanes is an important and challenging topic in several areas of chemistry in particular in the chemistry of the atmosphere. Among the class of halomethanes, the diiodomethane molecule has attracted some interest in the last years, but despite this, the information on its radical cation[CH2I2]·+is still limited. In this work, we measured and calculated the appearance energy (AE) of the ionic fragments I2·+and CH2·+and correlated the different fragmentation channels to the electronic states of the cation via photoelectron-photoion coincidence (PEPICO) experiments.In the case of the CH2/I2·+ channel, the experimentally determined AE is in excellent agreementwith the adiabatic theoretical value while a discrepancy is observed for the CH2·+/I2channel.This discrepancy can be understood accounting for a fragmentation involving the formation oftwo I atoms (CH2·+/2I channel), which, as explained by time dependent density functional theory(TD-DFT) calculations, occurs when[CH2I2]·+ excited states are involve

Perspectives of Gas Phase Ion Chemistry: Spectroscopy and Modeling

The study of ions in the gas phase has a long history and has involved both chemists and physicists. The interplay of their competences with the use of very sophisticated commercial and/or homemade instrumentations and theoretical models has improved the knowledge of thermodynamics and kinetics of many chemical reactions, even if still many stages of these processes need to be fully understood. The new technologies and the novel free-electron laser facilities based on plasma acceleration open new opportunities to investigate the chemical reactions in some unrevealed fundamental aspects. The synchrotron light source can be put beside the FELs, and by mass spectrometric techniques and spectroscopies coupled with versatile ion sources it is possible to really change the state of the art of the ion chemistry in different areas such as atmospheric and astro chemistry, plasma chemistry, biophysics, and interstellar medium (ISM). In this manuscript we review the works performed by a joint combination of the experimental studies of ion–molecule reactions with synchrotron radiation and theoretical models adapted and developed to the experimental evidence. The review concludes with the perspectives of ion–molecule reactions by using FEL instrumentations as well as pump probe measurements and the initial attempt in the development of more realistic theoretical models for the prospective improvement of our predictive capability

VUV Photofragmentation of Chloroiodomethane: The Iso-CH2I–Cl and Iso-CH2Cl–I Radical Cation Formation

Dihalomethanes XCH2Y (X and Y= F, Cl, Br and I) are a class of compounds involved in several processes leading to the release of halogen atoms, ozone consumption and aerosol particle formation. Neutral dihalomethanes have been largely studied, but chemical physics properties and processes involving their radical ions, like the pathways of their decomposition, have not been completely investigated. In this work the photodissociation dynamics of the ClCH2I molecule has been explored in the photon energy range 9-21 eV using both VUV rare gas discharge lamps and synchrotron radiation. The experiments show that among the different fragment ions, CH2I+ and CH2Cl+, which correspond to the Cl- and I-losses, respectively, play a dominant role. The experimental ionization energy of ClCH2I and the appearance energies of the CH2I+ and CH2Cl+ ions are in agreement with the theoretical results obtained at the MP2/CCSD(T) level of theory. Computational investigations have been also performed to study the isomerization of geminal [ClCH2I].+ into the iso-chloroiodomethane isomers: [CH2I-Cl].+ and [CH2Cl-I].+

Ionization of 2- and 4(5)-Nitroimidazoles Radiosensitizers: a "Kinetic Competition" Between NO2 and NO Losses

Nitroimidazoles are a class of chemicals with a remarkable broad spectrum of applications from the production of explosives to the use as radiosensitizers in radiotherapy. The understanding of thedynamics of their fragmentation induced by ionizing sources is of fundamental interest. The goal of this work is to theoretically investigate the kinetic competition between the two most important decomposition channels of 2, 4 and 5-Nitroimidazole cations: the NO and NO2 losses. The calculated rate constants of the two processes are in very good agreement with the experimental Photoelectron-Photoion Coincidence (PEPICO) branching ratio. This study solves the intriguing and theoretically unexplained experimental observation that 2-Nitroimidazole, at variance with the other two regio-isomers is a source for only NO at low energies (<12.76 eV). This is a key point for biomedical application of the nitroimidazoles, because NO is the vasodilator that favors the reoxigenation of hypoxic tumor tissues

Inner shell photofragmentation of 2Cl-pyrimidine studied by mass spectrometry and electron–ion coincidence experiments

Photoelectron spectroscopy, mass spectrometry and electron–ion coincidence experiments combined with tunable synchrotron radiation have been used to study the decay and fragmentation of 2Cl-pyrimidine after Cl(2p), C(1s) and N(1s) excitations. The goal is to investigate how the state- and site-selected excitation and the chemical environment affect the fragmentation paths of the molecule and to make a comparison with fragmentation induced by direct valence ionization. It has been found that the site-selective inner shell excitation affects the branching ratio of the fragments, while the particular fragmentation channels of the cation are determined by the final state populated in the resonant decay of the core excited states. Effects of nuclear motion in the core excited states and the possible ultrafast molecular dissociation following the Cl(2p → σ*) core excitation are discussed