170,639 research outputs found
Tris(pyrazol-1-yl)borate and Tris(pyrazol-1-yl)methane: A DFT Study of Their Different Binding Capability Toward Ag(I) and Cu(I) Cations
No full textDensity functional theory has been used to study the electronic structure of [M(tp)] and [M(tpm)]+ conformers (M = Cu, Ag; tp = tris(pyrazol-1-yl)borate anion, tpm = tris(pyrazol-1-yl)methane) and the energetics of their interconversions. Results for the free tp ligand are similar to those of tpm [M. Casarin, D. Forrer, F. Garau, L. Pandolfo, C. Pettinari, A. Vittadini, J. Phys. Chem. A 112 (2008) 6723], indicating an intrinsic instability of the tripodal conformation (k3-like). This points out that, though frequently observed, the k3-coordinative mode is unlikely to be directly achieved through the interaction of M(I) with the k3-like tp/tpm conformer. Analogously to the [M(tpm)]+ molecular ions, the energy barrier for the k2-[M(tp)] → k3-[M(tp)] conversion is computed to be negligible. Though kn-[M(tp)] and kn-[M(tpm)]+ (n = 1, 2, 3) have similar metal–ligand covalent interactions, the negative charge associated to the tp ligand makes the M-tp bonding stronger
A discussion on: Approximate Bayesian inference for latent Gaussian models by using integrated nested Laplace approximations by Rue, H. Martino, S. and Chopin, N.
No full textThis is a discussion of the work Rue et al. (2009).
In order to evaluate the impact of their Gaussian approximation on the marginal posterior we consider here a slightly different albeit standard stochastic volatility model. We propose a pluggin approximation that is readily available, contrary to the mode of the full conditional suggested in Rue et al. (2009). We obtain a straightforward recurrence relations
L'etude marketing du comportament du touriste. Problemes theoriques et enjeux operationnels
No full textLong-term follow-up of non-A, non-B (type C) post-transfusion hepatitis.
No full textOne hundred and thirty-five patients who developed non-A, non-B post-transfusion hepatitis mostly after cardiac surgery, were followed for a mean (+/- S.D.) of 90 +/- 41 months (range: 13-180) to evaluate clinical and histological outcome. Thirty-one cases resolved within 12 months, while 104 (77%) progressed to chronicity. Twenty-one of 65 (32%) biopsied patients developed cirrhosis at the end of the follow-up, and one further progressed to hepatocellular carcinoma. One patient had a complete histological remission (1%). The remaining cases had chronic active (37%), chronic persistent (27%) or chronic lobular hepatitis (3%). About half of the cases with cirrhosis developed portal hypertension, and three of these died due to esophageal varices hemorrhage, one due to liver failure, and one due to hepatocellular carcinoma. Out of 26 patients with the initial histologic diagnosis of chronic hepatitis that were rebiopsied during follow-up, 13 (50%) progressed to cirrhosis. These patients were significantly older than patients who did not develop cirrhosis (mean age 57 and 45 years respectively; p < 0.01). During acute hepatitis anti-HCV was positive in all but one of the 114 patients tested. Percentages were similar for patients who recovered (95%) and those who developed chronic hepatitis (100%). However, during follow-up, 71% of the 1st generation and 21% of the 2nd generation ELISA test patients with acute resolved hepatitis became anti-HCV negative, while the same figures in chronic cases were only 8.5% (p < 0.0001) and 1.4% (p = 0.012). This suggests a correlation between anti-HCV antibody activity, hepatitis C virus replication, and the development of chronic liver disease
A Quasi-Relativistic Density Functional Study of Structural and Electronic Properties of the Bis-Ketene Cis-[Pt{η3-C3H5}{η1-C(PPh3)CO}2]+
No full textQuasi-relativistic density functional calculations have been used to look into the molecular and electronic properties of cis-[Pt(η3-C3H5){η1-C(PPh3)(CO)}2]BF4. Numerical experiments have been run for both isomers compatible with IR and NMR outcomes. Binding energies and computed CCO stretching frequencies are very similar for both species, thus indicating their possible coexistence in solution. The comparison with homogeneous theoretical data pertaining to cis/trans-[Pt(η3-C3H5)2] and trans-[PtCl2{η1-C(PPh3)(CO)}2] provides a rationale of the [Pt(η3-C3H5){η1-C(PPh3)(CO)}2]BF4 low stability
Solution Manual for Selected Problems, The Bayesian Choice, 2nd Ed. and Paperback Ed., C. P. Robert.Springer Verlag
No full textRegioselectivity in reactions between bis(2-benzothiazolyl)ketone and vinyl grignard reagents: C- versus o-alkylation—Part III
No full textThe reaction between bis(2-benzothiazolyl)ketone and vinyl Grignard reagents bearing different substituents on the vinyl moiety gave the product derived from attack on the carbonylic carbon- and/or oxygen-atom. The regioselectivity of the attack depends on the kind of substituents bound to the vinylic carbon atoms and on their relative position. The reaction between vinylmagnesium bromide and 2-methyl-1-propenylmagnesium bromide was carried out under different experimental conditions and in the presence of radical scavengers. The results indicate a plausible mechanistic pathway involving radical intermediates in the case of O-alkylation, but a polar ones in the case of classic C-alkylation. This agrees with our previous reports indicating a key role played by the delocalization ability of the substituents bound to the carbonyl group in driving the regioselectivity of the vinylmagnesium bromide attack towards O-alkylation. Further support of this was obtained by diffractometric analysis of four distinct bis(heteroaryl)ketones
Tris(pyrazol-1-yl)borate and tris(pyrazol-1-yl)methane: A DFT study of their different binding capability toward Ag(I) and Cu(I) cations
No full text@Unicam(opens in a new window)|@Unicam(opens in a new window)|Order document via Nilde(opens in a new window)|View at Publisher|
Export
| Download | Add to List | More...
Inorganica Chimica Acta
Volume 362, Issue 12, 15 September 2009, Pages 4358-4364
Tris(pyrazol-1-yl)borate and tris(pyrazol-1-yl)methane: A DFT study of their different binding capability toward Ag(I) and Cu(I) cations (Article)
Casarin, M.acd , Forrer, D.ad, Garau, F.a, Pandolfo, L.ad, Pettinari, C.b, Vittadini, A.cd
a Dipartimento di Scienze Chimiche, Università degli Studi di Padova, Via Marzolo 1, 35131 Padova, Italy
b Dipartimento di Scienze Chimiche, Camerino, Italy
c Istituto di Scienze Molecolari, CNR, Padova, Italy
View additional affiliations
View references (62)
Abstract
Density functional theory has been used to study the electronic structure of [M(tp)] and [M(tpm)]+ conformers (M = Cu, Ag; tp = tris(pyrazol-1-yl)borate anion, tpm = tris(pyrazol-1-yl)methane) and the energetics of their interconversions. Results for the free tp ligand are similar to those of tpm [M. Casarin, D. Forrer, F. Garau, L. Pandolfo, C. Pettinari, A. Vittadini, J. Phys. Chem. A 112 (2008) 6723], indicating an intrinsic instability of the tripodal conformation (κ3-like). This points out that, though frequently observed, the κ3-coordinative mode is unlikely to be directly achieved through the interaction of M(I) with the κ3-like tp/tpm conformer. Analogously to the [M(tpm)]+ molecular ions, the energy barrier for the κ2-[M(tp)] → κ3-[M(tp)] conversion is computed to be negligible. Though κn-[M(tp)] and κn-[M(tpm)]+ (n = 1, 2, 3) have similar metal-ligand covalent interactions, the negative charge associated to the tp ligand makes the M-tp bonding stronger
PREDICTORS OF SUSTAINED RESPONSE, RELAPSE AND NO RESPONSE IN PATIENTS WITH CHRONIC HEPATITIS C TREATED WITH INTERFERON ALPHA
No full textThree main patterns of response are seen when interferon-alpha (IFN-alpha) is used for the treatment of chronic hepatitis C: 1 sustained response with alanine-aminotransferase (ALT) normalization that is maintained after cessation of therapy, with or without clearance of serum hepatitis C virus (HCV) RNA; 2 transient response with ALT normalization during therapy followed by relapse after its withdrawal, and 3 no response with no or only partial reduction in ALT levels. In order to define variables that could predict each of these three types of response we studied 321 cases of chronic hepatitis C treated with IFN-alpha in two consecutive trials conducted in our Unit. By univariate analysis, age 45 years (P < 0.01), body weight (P = 0.05), cirrhosis (P < 0.01) and elevated gamma GT levels (P < 0.01) were associated with no response. By multivariate analysis sustained response was predicted by HCV genotype 2 (P < 0.01) and HCV genotype 3 (P < 0.01), known disease duration (P < 0.01), patient's age (P < 0.05) and associated with the use of a more aggressive treatment schedule (P < 0.05). Transient response with relapse was predicted by known duration of disease (P < 0.05), HCV genotype 1 (P < 0.05) and female sex (P < 0.05). No response was statistically associated with elevated gamma GT levels (P < 0.01), higher body weight (P < 0.05) and with the less aggressive regimen of 3 MU of natural IFN-alpha given three times weekly for 6 months (P < 0.05). These results indicate that the HCV genotype as well as the schedule of treatment greatly affect the pattern of response to IFN in chronic hepatitis C and allow us to define criteria to predict which type of response is more likely in individual patients
- …
