Can neutral and ionized PAHs be carriers of the UV extinction bump and the diffuse interstellar bands?

Up to now, no laboratory-based study has investigated polycyclic aromatic hydrocarbon (PAH) species as potential carriers of both the diffuse interstellar bands (DIBs) and the 2175 A UV bump. We examined the proposed correlation between these two features by applying experimental and theoretical techniques on two specific medium-sized/large PAHs (dibenzorubicene C30H14 and hexabenzocoronene C42H18) in their neutral and cationic states. It was already shown that mixtures of sufficiently large, neutral PAHs can partly or even completely account for the UV bump. We investigated how the absorption bands are altered upon ionization of these molecules by interstellar UV photons. The experimental studies presented here were realized by performing matrix isolation spectroscopy with subsequent far-UV irradiation. The main effects were found to be a broadening of the absorption bands in the UV combined with slight red shifts. The position of the complete pi - pi* absorption structure around 217.5 nm, however, remains more or less unchanged which could explain the observed position invariance of the interstellar bump for different lines of sight. This favors the assignment of this feature to the interstellar PAH population. As far as the DIBs are concerned, neither our investigations nor the laboratory studies carried out by other research groups support a possible connection with this class of molecules. Instead, there are reasonable arguments that neutral and singly ionized cationic PAHs cannot be made responsible for the DIBs.Comment: 11 pages, 7 figures, 1 tabl

Treatment options for proximal periprosthetic femoral fractures in Total Hip Arthroplasty: a single center experience

objective: proximal periprosthetic femoral fractures (PPFFs) are gradually increasing and surgical management is often associated with high risk of complications, due to elderly population and associated comorbidities. patients and methods: we retrospectively assessed 39 patients at least at 2-years follow-up. we identified two study groups, similar for demographic data. group a included patients surgically treated without involving prosthetic implants, whereas group B included patients in which an implant revision was performed. results: data were recorded from January 2017 to february 2020, and 39 patients were included: 30 females (76.9%) and 9 males (23.1%), with a confirmed diagnosis of periprosthetic fracture of the proximal femur. 23 (58.9%) patients were treated with open reduction and Internal fixation (ORIF), 12 (30.7%) with revision surgery and 4 (10.3%) were treated by modular megaprosthesis. conclusions: the treatment options considered in the study, revision arthroplasty and internal fixation had shown no significant differences as a matter of clinical outcomes and postoperative complications

Evaluating Treatment Outcomes for Pelvic Insufficiency Fractures: A Systematic Review

background: pelvic insufficiency fractures (PIF) are typical in geriatric populations with reduced bone quality, most commonly in elderly postmenopausal women. these fractures are usually caused by low-energy forces over the bones during ordinary life and cause disabling pain. treatment options range from conservative to operative. the aim of this study is to assess the outcomes of treatments for pelvic insufficiency fractures, determining optimal approaches between surgical intervention and conservative management. methods: this literature review systematically examines articles focusing on patients with PIF, following the peferred reporting Items for systematic reviews and meta-analyses guidelines, and using pubmed, medline, and the cochrane library database. we took into account only full-text articles in indexed journals with available english abstracts, considering data about patient demographics, surgery, and outcomes. results: after screening 128 articles, this study reviewed 20 manuscripts involving 1499 patients, mostly elderly females and focusing on sacrum fractures. common treatments included conservative methods and sacroplasty, with a few complications reported. osteoporosis was the prevalent comorbidity, and the survival rate post-treatment was high at 92.3%. mobility outcomes varied, with some patients experiencing significant autonomy loss. the average follow-up period was over 17 months. conclusions: this study found a cautious approach to surgery (timing of three weeks), which is reserved only for specific patterns, and it leads to increased autonomy and a lower risk of mortality. due to the lack of pre- and postoperative scores as well as conflicting results, it is imperative to undertake further studies and research to be able to compare the alternative treatments efficiently

Effectiveness of cardiac resynchronization therapy in heart failure patients with valvular heart disease: comparison with patients affected by ischaemic heart disease or dilated cardiomyopathy. The InSync/InSync ICD Italian Registry

AimsTo analyse the effectiveness of cardiac resynchronization therapy (CRT) in patients with valvular heart disease (a subset not specifically investigated in randomized controlled trials) in comparison with ischaemic heart disease or dilated cardiomyopathy patients.Methods and resultsPatients enrolled in a national registry were evaluated during a median follow-up of 16 months after CRT implant. Patients with valvular heart disease treated with CRT (n = 108) in comparison with ischaemic heart disease (n = 737) and dilated cardiomyopathy (n = 635) patients presented: (i) a higher prevalence of chronic atrial fibrillation, with atrioventricular node ablation performed in around half of the cases; (ii) a similar clinical and echocardiographic profile at baseline; (iii) a similar improvement of LVEF and a similar reduction in ventricular volumes at 6-12 months; (iv) a favourable clinical response at 12 months with an improvement of the clinical composite score similar to that occurring in patients with dilated cardiomyopathy and more pronounced than that observed in patients with ischaemic heart disease; (v) a long-term outcome, in term of freedom from death or heart transplantation, similar to patients affected by ischaemic heart disease and basically more severe than that of patients affected by dilated cardiomyopathy.ConclusionIn 'real world' clinical practice, CRT appears to be effective also in patients with valvular heart disease. However, in this group of patients the outcome after CRT does not precisely overlap any of the two other groups of patients, for which much more data are currently available

Matrix isolation spectroscopy of C70 - vibrational analysis and assignment of the lowest excited states

Highly structured fluorescence and fluorescence excitation spectra of C70 in Ne matrixes are reported. Fluorescence from both S1 and S2 states is obsd., and these are identified as being of A2' and E1' and have energies of 15,524 cm-1 and 15,691 cm-1, resp. A 3rd singlet state is identified in the excitation spectrum and probably is of A2 symmetry with an energy of 15,966 cm-1. [on SciFinder (R)]LS

ASSIGNMENT OF THE LOWEST EXCITED STATES OF C70C_{70} AND EVIDENCE FOR FLUORESCENCE FROM THE SINGLET S2S_{2} STATE

Author Institution: Institut de Physique Exp\'{e}rimenta***e, Universit\'{e} de LausanneHighly structured fluorescence, phosphorescence and fluorescence-excitation spectra of $C_{70}$ in neon matrices are reported. Fluorescence from both $S_{1}$ and $S_{2}$ states is observed and these are identified as being of $A^{\prime}_{2}$ and $E^{\prime}_{1}$ symmetry and have gas phase energies estimated at 15560 and $15725 cm^{-1}$, respectively. A third singlet state is identified in the excitation spectrum and is proposed to be of $A^{\prime \prime}_{2}$ symmetry with an estimated gas phase energy of $16000 cm^{-1}$. Finally, the phosphorescence is dominated by vibrational bands of $e^{\prime}_{1}$ symmetry pointing to a lowest triplet state of $A^{\prime}_{2}$ symmetry. Its energy lies at $12588 cm^{-1}$ above that of the ground state in the neon matrix. From a comparison with data from the literature, the existence of a second triplet state of $E^{\prime}_{1}$ character is inferred, which lies about $165 cm^{-1}$ above the lowest triplet state, i.e. with the same energy separation as the lowest two singlet states