Reactions of C5H5M+ (M=Fe, Ni) with substituted thiophenes.

The ion molecule reactions between C5H5M+ (M =Fe, Ni) with some substituted thiophenes have been studied in an ion trap mass spectrometer. The reactions of halogen substituted thiophenes lead to the formation of a new C\u2013C bond between the cyclopentadiene ring and the thiophene with the loss of a neutral HX. The reaction mechanism has been investigated by means of DFT calculations

Mechanism of the gas phase reactions of the C5H5Ni+ and C5H5Co+ ions with substituted pyridines. A combined experimental and theoretical study

Different products have been observed in the reactions ofC5H5Co+ andC5H5Ni+ ions with halogen-substituted pyridines (XPy) that have been studied by ion trap mass spectrometry (ITMS) techniques.In particular,an addition product C5H5M(XPy)+and a product ion C5H4M(Py)+ corresponding to a loss of a HX molecule(X =F,Cl,Br)havebeen detected. Acomputational study at the DFT level on model-systems formed by 2-fluoro and 2-bromopyridine reacting either with the C5H5Ni+ or the C5H5Co+ ion has been carried out. This study shows the existence of a general mechanistic pattern. The rate-determining step of this mechanism is the migration of the halogen from the pyridine ring to the metal. A final hydrogen abstraction step carried out by the halogen leads to the expulsion of a HX molecule

Is it better to use the radial artery as a composite graft? Clinical and angiographic results of aorto-coronary versus Y-graft

OBJECTIVE: We sought to evaluate whether the radial artery (RA) provides the same clinical and angiographic results when proximally anastomosed to the aorta or to the left internal thoracic artery (ITA) as a composite Y-graft. METHODS: From February 1999 to December 2002, 512 patients underwent myocardial revascularization using the RA, the left ITA and, when required, the saphenous vein. According to the surgeons' preference the RA was proximally anastomosed to the aorta [336 patients (65.6%), Ao-Cor group] or to the left ITA as a composite Y-graft [176 patients (34.4%), Y-graft group]. There was a significant prevalence of three-vessel disease (86.8 versus 73.2%, (P = 0.000) and elderly age (60+/-9 versus 58+/-8 years, (P = 0.014) in the Y-graft group. RESULTS: Patients in Y-graft group had longer aortic cross clamp time (P = 0.001), more bypass grafts per patient (P < or = 0.001) more arterial bypass grafts per patient (P < or = 0.001) and more bypass grafts per patient with the RA (P < or = 0.001). There were no differences in terms of perioperative outcome. Mean follow-up time was 27.1+/-11.7 months in 322/333 (96.7%) patients of the Ao-Cor group and 14.9+/-10.2 in 165/172 (95.9%) patients of the Y-graft group. There was no difference in terms of overall survival (P = 0.75) cardiac event-free survival (P = 0.65) RA patency rate at postoperative angiography (P = 0.59) and during follow-up (P = 0.93). A preoperative coronary artery stenosis < or = 70% was related with competitive flow (P = 0.000) at postoperative angiography and with RA occlusion (P = 0.001) at follow-up angiography. CONCLUSIONS: The RA provides the same clinical and angiographic results both as aorto-coronary and composite Y-graft with the left ITA. When the RA is used as Y-graft the procedure is more technically demanding and a greater number of distal coronary anastomoses is possible. RA grafts to targets with stenosis < or = 70% appear to be at risk of failur

Analysis of Y-graft blood flow and flow reserve in conditions of increased myocardial oxygen consumption

Background: It is not well established whether early following surgery the blood flow of arterial composite Y-grafts may efficiently meet the flow demand of the coronary system. The aim of this study was to evaluate whether early after surgery arterial composite Y-grafts may increase the blood flow in response to an increase in myocardial oxygen consumption (MVO2). Methods: Twenty-seven patients who received complete arterial myocardial revascularization using the left internal thoracic artery (LITA) and the radial artery (RA) as composite Y-graft gave their consent to a pre-discharge coronary angiography and intravascular flow velocity measurements using a Doppler guidewire. Flow measurements were performed in the LITA main stem, the distal LITA and the RA, both at rest and during atrial pacing at 85% of the patient age-predicted maximum heart rate. The heart rate-systolic blood pressure product was considered as an indirect index of MVO2. Hyperemic flow was determined after injection of adenosine. The flow reserve was defined as the ratio of blood flow during maximal hyperemia (Qmax) to baseline flow (Qbasal). Results: Atrial pacing significantly increased MVO2 (p < 0.000). None of the patients developed ischemic ST-segment modifications or complained of chest pain. Qbasal increased significantly in the LITA main stem (p = 0.001), distal LITA (p = 0.041) and RA (p = 0.004) while Qmax did not change significantly. As a consequence the flow reserve decreased in the LITA main stem (p = 0.002), distal LITA (p = 0.000) and RA (p = 0.000) but was not completely exhausted. Conclusions: Early after surgery arterial composite Y-grafts may significantly increase blood flow in response to conditions of increased MVO2 and maintain a normal myocardial oxygen supply-to-demand ratio

Solid acid chemohydrolysis of untreated lignocellulose: comparing the reaction kinetics with various catalyts

none7noneG. Gliozzi; A. Innorta; A. Mancini; F. Cavani; R. Bortolo; M. Ricci; C. PeregoG. Gliozzi; A. Innorta; A. Mancini; F. Cavani; R. Bortolo; M. Ricci; C. Pereg