131,180 research outputs found
Surgical treatment for intrahepatic cholangiocarcinoma
No full textIntrahepatic cholangiocarcinoma is an aggressive tumor usually discovered at an advanced stage. Surgical resection is the treatment of choice but less than 50% of patients may receive curative resection. In almost 70% of patients, extended hepatectomy with vascular resection and/or bile duct resection are required to achieve a negative margin. Overall 5-year survival is around 30%. Prognosis is mainly based on tumor factors such as size, number, lymph node or vascular invasion and surgical margin. The main sites of recurrence are the liver, peritoneum and lymph nodes. In patients with liver-only recurrence, re-resection should always be considered.Intrahepatic cholangiocarcinoma is an aggressive tumor usually discovered at an advanced stage. Surgical resection is the treatment of choice but less than 50% of patients may receive curative resection. In almost 70% of patients, extended hepatectomy with vascular resection and/or bile duct resection are required to achieve a negative margin. Overall 5-year survival is around 30%. Prognosis is mainly based on tumor factors such as size, number, lymph node or vascular invasion and surgical margin. The main sites of recurrence are the liver, peritoneum and lymph nodes. In patients with liver-only recurrence, re-resection should always be considered
Aeternitas e il crescente lunare in età repubblicana, ovvero la riabilitazione di Tarpeia,
No full textPhysical basis of self-assembly. Part 2. A theoretical and experimental study of the self-assembly of a zinc meso-pyridyl porphyrin
No full textA previously reported theoretical treatment for self-assembly macrocyclisations occurring under thermodynamic control has been tested experimentally. The fundamental quantities on which the treatment is based are the effective molarity (EM) of the self-assembling cyclic n-mer and the equilibrium constant for the intermolecular model reaction between monofunctional reactants (Kinter). Provided that estimates of EM and Kinter are available, this treatment can be used to predict not only whether the self-assembly process is more or less favoured, but also the distribution of all the species present in solution. Since Kinter values are approximately known from the literature, we have proposed a method, based on molecular modelling techniques, to estimate the EM. The method has been applied to the self-assembly of Zn(PyP3P), where PyP3P is 5-(4-pyridyl)-10,15,20-triphenylporphyrinato dianion. An EM greater than 0.1 mol L-1 has been estimated for its cyclotetramerisation by PM3 calculations, suggesting that self-assembly should be favoured in solvents like toluene and chloroform. Self-assembly of Zn(PyP3P) has been studied in these solvents by UV/visible spectroscopy. The data are consistent with the formation of the cyclotetramer, and at variance with the model of linear polymerisation. The experimental values of the EM were little affected by the nature of the solvent (EM values were 20 mol L-1 in toluene and 15 mol L-1 in chloroform), indicating that the solvent affects the process of self-assembly mainly through the value of Kinter
Catenation equilibria between ring oligomers and their relation to effective molarities: Models from theories and simulations
No full textFive models are discussed giving the equilibrium constant for the catenation of two ring oligomers as a function of their Effective Molarity (EM), the physico-chemical parameter expressing the ease of cyclization of a chain. The first three models (A–C) are derived from the revision of previous theories of catenation, that neglect excluded volume effects. A fourth model (D) is obtained from the results of Monte Carlo simulations by Deguchi and co, that can also account for excluded volume effects. Finally, a fifth model (E) is introduced which has the same functional form of models A, B, D, but is parameterized using the available experimental catenation constant
The use of calf bone in young patients treated with acetabulum osteotomy
No full textThe use of calf bone in young patients treated with acetabulum osteotom
Experimental analysis of solid sediment behaviour in sloping pipes for solid-liquid mixtures.
No full text
Role of face-to-face and edge-to-face aromatic interactions in the inclusion complexation of cyclobis(paraquat-p-phenylene): A theoretical study
No full textA B3LYP/6-31G(d,p) and MP2/6-31G(d,p)//B3LYP/6-31G(d,p) computational study of the gas-phase complexation of cyclobis(paraquat-p-phenylene) (14+) with four typical aromatic guests, namely, 1,4-dimethoxybenzene (2), 1,5-dimethoxynaphthalene (3), benzidine (4), and tetrathiafulvalene (5), has been carried out. The structure of the host has been successively split into two responsible substructures, respectively, for the face-to-face and edge-to-face interactions with the guests. The sum of the two interactions calculated at the B3LYP/6-31G(d,p) and MP2/6-31G(d,p)//B3LYP/6-31G(d,p) levels for each guest proved to be in good agreement with the overall binding energy of the host calculated at the corresponding level of theory. The results show that the binding of the complexes is primarily due to London dispersion interactions which require wave function-based correlation methods for an adequate description. Face-to-face interactions are about I order of magnitude more important than edge-to-face interactions in determining the overall binding energy. While edge-to-face interactions essentially depend on London dispersion forces, face-to-face interactions depend about one-half on electrostatic and frontier orbital contributions (the latter being more important) and the other half on London dispersion forces
Physical basis of self-assembly. Part 2. A theoretical and experimental study of the self-assembly of a zinc meso-pyridyl porphyrin
No full textA previously reported theoretical treatment for self-assembly macrocyclisations occurring under thermodynamic control has been tested experimentally. The fundamental quantities on which the treatment is based are the effective molarity (EM) of the self-assembling cyclic n-mer and the equilibrium constant for the intermolecular model reaction between monofunctional reactants (K-inter). Provided that estimates of EM and K-inter are available, this treatment can be used to predict not only whether the self-assembly process is more or less favoured, but also the distribution of all the species present in solution. Since K-inter values are approximately known from the literature, we have proposed a method, based on molecular modelling techniques, to estimate the EM. The method has been applied to the self-assembly of Zn(PyP3P), where PyP3P is 5-(4-pyridyl)-10,15,20-triphenylporphyrinato dianion. An EM greater than 0.1 mol L-1 has been estimated for its cyclotetramerisation by PM3 calculations, suggesting that self-assembly should be favoured in solvents like toluene and chloroform. Self-assembly of Zn(PyP3P) has been studied in these solvents by UV/visible spectroscopy. The data are consistent with the formation of the cyclotetramer, and at variance with the model of linear polymerisation. The experimental values of the EM were little affected by the nature of the solvent (EM values were 20 mol L-1 in toluene and 15 mol L-1 in chloroform), indicating that the solvent affects the process of self-assembly mainly through the value of K-inter
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