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1.
Phys Chem Chem Phys ; 14(43): 15145-57, 2012 Nov 21.
Artigo em Inglês | MEDLINE | ID: mdl-23042085

RESUMO

Calcite-water interactions are important not only in carbon sequestration and the global carbon cycle, but also in contaminant behaviour in calcite-bearing host rock and in many industrial applications. Here we quantify the effect of variations in surface structure on calcite surface reactivity. Firstly, we employ classical Molecular Dynamics simulations of calcite surfaces containing an etch pit and a growth terrace, to show that the local environment in water around structurally different surface sites is distinct. In addition to observing the expected formation of more calcium-water interactions and hydrogen-bonds at lower-coordinated sites, we also observed subtle differences in hydrogen bonding around acute versus obtuse edges and corners. We subsequently used this information to refine the protonation constants for the calcite surface sites, according to the Charge Distribution MUltiSite Ion Complexation (CD-MUSIC) approach. The subtle differences in hydrogen bonding translate into markedly different charging behaviour versus pH, in particular for acute versus obtuse corner sites. The results show quantitatively that calcite surface reactivity is directly related to surface topography. The information obtained in this study is not only crucial for the improvement of existing macroscopic surface models of the reactivity of calcite towards contaminants, but also improves our atomic-level understanding of mineral-water interactions.

2.
Int J Impot Res ; 17(3): 224-6, 2005.
Artigo em Inglês | MEDLINE | ID: mdl-15716979

RESUMO

Female sexual dysfunction (FSD) is a significant public health problem. We assessed the prevalence of FSD in premenopausal women with the metabolic syndrome as compared to the general female population. Compared with the control group (N = 80), women with the metabolic syndrome (N = 120) had reduced mean full Female Sexual Function Index (FSFI) score (23.2+/-5.4 vs 30.1+/-4.7, P < 0.001), reduced satisfaction rate (3.5+/-1.1 vs 4.7+/-1.2, P < 0.01), and higher circulating levels of C-reactive protein (CRP: 2.2 (0.6/4.9) vs 0.8 (0.2/2.9) mg/l, median (interquartile range), P = 0.01). There was an inverse relation between CRP levels and FSFI score (r = -0.32, P=0.02). Investigation of female sexuality is suggested for patients with the metabolic syndrome.


Assuntos
Síndrome Metabólica/complicações , Disfunções Sexuais Fisiológicas/etiologia , Adulto , Glicemia/análise , Proteína C-Reativa/análise , HDL-Colesterol/sangue , Jejum , Feminino , Humanos , Pessoa de Meia-Idade , Orgasmo , Comportamento Sexual/fisiologia , Triglicerídeos/sangue
3.
Br J Pharmacol ; 127(3): 747-55, 1999 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-10401566

RESUMO

1. The effects of ethyl alcohol and wine (red and white) on haemostatic parameters and experimental thrombosis were studied in rats; NO was evaluated as a possible mediator of these effects. 2. We found that red wine (12% alcohol) supplementation (8.4 +/- 0.4 ml d-1 in drinking water, for 10 days) induced a marked prolongation of 'template' bleeding time (BT) (258 +/- 13 vs 132 +/- 13 s in controls; P < 0.001), a decrease in platelet adhesion to fibrillar collagen (11.6 +/- 1.0 vs 32.2 +/- 1.3%; P < 0.01) and a reduction in thrombus weight (1.45 +/- 0.33 vs 3.27 +/- 0.39 mg; P < 0.01). 3. Alcohol-free red wine showed an effect similar to red wine. In contrast, neither ethyl alcohol (12%) nor white wine (12% alcohol) affected these systems. 4. All these effects were also observed after red wine i.v. injection (1 ml kg-1 of 1:4 dilution) 15 min before the experiments. 5. The effects of red wine were prevented by the NO inhibitor, N omega nitro-L-arginine-methyl ester (L-NAME). L-arginine, not D-arginine, reversed the effect of L-NAME on red wine infusion. 6. Red wine injection induced a 3 fold increase in total radical-trapping antioxidant parameter values of rat plasma with respect to controls, while white wine and alcohol did not show any effect. 7. Our study provides evidence that red wine modulates primary haemostasis and prevents experimental thrombosis in rats, independently of its alcohol content, by a NO-mediated mechanism.


Assuntos
Hemostasia/fisiologia , Óxido Nítrico/biossíntese , Trombose/sangue , Trombose/prevenção & controle , Vinho , Administração Oral , Animais , Antioxidantes/metabolismo , Tempo de Sangramento , Modelos Animais de Doenças , Etanol/sangue , Radicais Livres/sangue , Injeções Intravenosas , Masculino , Óxido Nítrico/sangue , Óxido Nítrico/fisiologia , Prostaglandina-Endoperóxido Sintases/metabolismo , Ratos , Ratos Sprague-Dawley , Trombose/metabolismo
4.
J Chem Phys ; 127(14): 144312, 2007 Oct 14.
Artigo em Inglês | MEDLINE | ID: mdl-17935400

RESUMO

Valence band and C 1s core-level photoelectron spectra of S-(+)-2-amino-1-propanol (alaninol) and S-(+)-1-amino-2-propanol (isopropanolamine) have been studied by means of synchrotron radiation photoelectron spectroscopy in gas phase. The alaninol, the reduced derivative of the alanine, is a good test system of amino acid-like structures. The isopropanolamine, presenting the inversion of the two functional groups of the alaninol at the chiral carbon, offers the opportunity to study the effect of -OH and -NH(2) structural position on the photoelectron spectra. The influence of the conformational contribution on the electronic structure and the photoelectron spectra has been interpreted using density functional and ab initio theoretical calculations. Agreement has been achieved by taking into account the presence, in gas phase, of two conformers with different population ratios in both chiral systems. The C 1s core-level spectra of alaninol and isopropanolamine are reported and the peak positions of the three carbon atoms of the molecules are assigned.


Assuntos
Aminoácidos/química , Carbono/química , Propanolaminas/química , Análise Espectral/métodos , Algoritmos , Elétrons , Isomerismo , Conformação Molecular , Fotoquímica , Termodinâmica
5.
J Chem Phys ; 124(2): 024326, 2006 Jan 14.
Artigo em Inglês | MEDLINE | ID: mdl-16422602

RESUMO

In the present work the photoelectron circular dichroism of camphor has been theoretically studied using B-spline and continuum multiple scattering-Xalpha methods, and comparisons are made with available experimental data. In general, rather large dichroism effects have been found for both valence and core (O 1s, C 1s) photoionizations. The agreement between the two calculations reported here and previous experimental measurements for core C 1s data is essentially quantitative. For valence ionization satisfactory agreement between theory and experiment has been obtained and the discrepancies have been attributed to both exchange-correlation potential limitations and the absence of response effects in the adopted formalism. The calculations predict, moreover, important features in the cross-section profiles, which have been discussed in terms of dipole-prepared continuum orbitals.


Assuntos
Cânfora/química , Físico-Química/métodos , Carbono/química , Dicroísmo Circular , Elétrons , Íons , Cinética , Modelos Químicos , Modelos Estatísticos , Modelos Teóricos , Oxigênio/química , Espalhamento de Radiação , Software , Estereoisomerismo
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