University of Mons

About: University of Mons is a education organization based out in Mons, Belgium. It is known for research contribution in the topics: Large Hadron Collider & Standard Model. The organization has 3073 authors who have published 9465 publications receiving 294776 citations.

Theoretical investigation of the geometric and optical properties of neutral and charged oligophenylenes

Abstract: We have investigated the geometry and the nature of optically allowed transitions in neutral and charged phenylene-based oligomers by means of Hartree-Fock calculations. Geometry optimizations are performed using the semiempirical Austin Model 1 (AM1) method for oligomers containing from two $(2P)$ to twelve $(12P)$ benzene rings. The transition energies and related intensities of the optical-absorption spectra are calculated by means of the intermediate neglect of differential overlap Hamiltonian that is combined with a single configuration interaction technique in order to include electron correlation effects in the description of the excited states. The calculations show that two subgap absorption features appear in short oligomers carrying a single charge (polaron), whereas a single intense peak is observed in the presence of two charges (bipolaron). These results are consistent with a wide range of experimental and theoretical data obtained for various conjugated oligomers. Interestingly, the appearance of a second subgap feature is predicted in the spectra of long doubly oxidized chains as well as for chains supporting interacting bipolarons.

Antioxidant properties of phenolic Schiff bases: structure-activity relationship and mechanism of action

Abstract: Phenolic Schiff bases are known for their diverse biological activities and ability to scavenge free radicals. To elucidate (1) the structure-antioxidant activity relationship of a series of thirty synthetic derivatives of 2-methoxybezohydrazide phenolic Schiff bases and (2) to determine the major mechanism involved in free radical scavenging, we used density functional theory calculations (B3P86/6-31+(d,p)) within polarizable continuum model. The results showed the importance of the bond dissociation enthalpies (BDEs) related to the first and second (BDEd) hydrogen atom transfer (intrinsic parameters) for rationalizing the antioxidant activity. In addition to the number of OH groups, the presence of a bromine substituent plays an interesting role in modulating the antioxidant activity. Theoretical thermodynamic and kinetic studies demonstrated that the free radical scavenging by these Schiff bases mainly proceeds through proton-coupled electron transfer rather than sequential proton loss electron transfer, the latter mechanism being only feasible at relatively high pH.

High incidence of high-risk HPV in benign and malignant lesions of the larynx

Abstract: The aim of this study was to determine the prevalence of human papillomavirus (HPV) in patients with laryngeal benign lesions (LBLs) and laryngeal squamous cell carcinomas (LSCCs) using a sensitive E6/E7 type-specific PCR. Paraffin-embedded samples from LBL (n=39) and LSCC patients (n=67) were evaluated for the presence of HPV DNA by GP5+/GP6+ consensus PCR and E6/E7 type-specific PCR for HPV types 6, 11, 16, 18, 31, 33, 35, 39, 45, 51, 52, 53, 56, 58, 59, 66 and 68. In LSCCs, immunohistochemical staining of p16, p53 and EGFR was also assessed. The E6/E7 type-specific PCR showed that 44 out of 59 LSCC patients (i.e., 75%) had high-risk (hr) HPV types and that 27 out of 35 LBL patients (i.e., 77%) had hrHPV types. HPV-16 viral load was significantly higher in LSCC than in LBL patients (p<10-6). The presence of hrHPV DNA did not correlate with the proportion of disease-free patients. Comparable levels of p16, p53 and EGFR expression were observed in the hrHPV+ tumor group (100% p16+, 56% p53+ and 97% EGFR+) and in the HPV- or low-risk (lr) HPV+ tumor group (92% p16+, 66% p53+ and 100% EGFR+). A very high prevalence of oncogenic HPV-16 was found in a series of benign and malignant laryngeal lesions. LSCC appears to be characterized by an active hrHPV infection. In LSCCs, the hrHPV+ subgroup had a similar prognosis (in terms of risk of recurrence) as the HPV- subgroup.