Surface energy and surface proton order of ice Ih.

Ice Ih is comprised of orientationally disordered water molecules giving rise to positional disorder of the hydrogen atoms in the hydrogen bonded network of the lattice. Here we arrive at a first principles determination of the surface energy of ice Ih and suggest that the surface of ice is significantly more proton ordered than the bulk. We predict that the proton order-disorder transition, which occurs in the bulk at approximately 72 K, will not occur at the surface at any temperature below surface melting.

Correlation of modification of heart rate recovery with adaptation to myocardial ischemia in a model of sequential exercise testings.

Background: Heart rate recovery (HRR) has been identified as a reliable predictor of cardiac mortality, correlated with autonomic tone. In a model of sequential exercise testings, we investigated the reproducibility of HRR and the association between HRR modification and myocardial adaptation to ischemia.

Methods: We studied 128 patients (mean age 62 +/- 9 years, 83% males) with angiographically documented coronary artery disease (CAD) and a first positive exercise testing, who agreed to undergo a second exercise testing after 24 hours.

Manipulation and control of hydrogen bond dynamics in absorbed ice nanoclusters.

Inelastic electron tunneling is used to explore the dynamics of ice nanoclusters adsorbed on Ag(111). The diffusion of entire nanoclusters or internal hydrogen bond rearrangement can be selectively controlled by injecting electrons either directly into the clusters themselves or indirectly ("indirect inelastic electron tunneling") into the substrate at distances of up to 20 nm from them; a reaction probability that oscillates with the tip-cluster lateral distance presents evidence that surface state electrons mediate the excitation. Density functional theory calculations reveal a strong sensitivity of the computed activation energies of the individual processes to the applied electrical field.

Engineering of the membrane of fibroblast cells with virus-specific antibodies: A novel biosensor tool for virus detection.

A novel concept for the assay of viral antigens is described. The methodological approach is based on a membrane-engineering process involving the electroinsertion of virus-specific antibodies in the membranes of fibroblast cells. As a representative example, Vero fibroblasts were engineered with antibodies against Cucumber mosaic virus (CMV) and used for the construction of an ultra-sensitive miniature cell biosensor system.

Density oscillations in a nanoscale water film on salt: insight from ab initio molecular dynamics.

The salt-water interface is one of the most important and common on earth, playing a prominent role in disciplines such as atmospheric science and biology. Despite the apparent simplicity of such interfaces, arguably the most fundamental question of what the nature and structure of the liquid water/salt interface is under ambient conditions remains unclear. Here we address this issue with an ab initio molecular dynamics simulation of a nanoscale liquid water film on NaCl.

Assessment of Organophosphate and Carbamate Pesticide Residues in Cigarette Tobacco with a Novel Cell Biosensor.

The conventional analysis of pesticide residues in analytical commodities, such as tobacco and tobacco products is a labor intensive procedure, since it is necessary to cover a wide range of different chemicals, using a single procedure. Standard analysis methods include extensive sample pretreatment (with solvent extraction and partitioning phases) and determination by GC and HPLC to achieve the necessary selectivity and sensitivity for the different classes of compounds under detection. As a consequence, current methods of analysis provide a limited sample capacity.

On the accuracy of density-functional theory exchange-correlation functionals for H bonds in small water clusters: benchmarks approaching the complete basis set limit.

The ability of several density-functional theory (DFT) exchange-correlation functionals to describe hydrogen bonds in small water clusters (dimer to pentamer) in their global minimum energy structures is evaluated with reference to second order Moller-Plesset perturbation theory (MP2). Errors from basis set incompleteness have been minimized in both the MP2 reference data and the DFT calculations, thus enabling a consistent systematic evaluation of the true performance of the tested functionals. Among all the functionals considered, the hybrid X3LYP and PBE0 functionals offer the best performance and among the nonhybrid generalized gradient approximation functionals, mPWLYP and PBE1W perform best.

Simulating ice nucleation, one molecule at a time, with the 'DFT microscope'.

Few physical processes are as ubiquitous as the nucleation of water into ice. However, ice nucleation and, in particular, heterogeneously catalyzed nucleation remains poorly understood at the atomic level. Here, we report an initial series of density functional theory (DFT) calculations aimed at putting our understanding of ice nucleation and water clustering at metallic surfaces on a firmer footing.

Tautomeric equilibria in phenolic A-ring derivatives of prodigiosin natural products.

The prodigiosin natural products contain a common 4-methoxy-pyrromethene chromophore that is attached to a pyrrole A-ring that has its lone-pair nitrogen electrons in conjugation with the pyrromethene entity. This feature is known to play a key role in the biological activities (anticancer, antimicrobial, and immunosuppressive) of the prodigiosins. In an attempt to alter or improve upon the therapeutic potential of the prodigiosins, we have synthesized two new isomeric analogues that contain phenolic A-ring systems (a para (p)-phenol; an ortho (o)-phenol with respect to the pyrromethene) with lone-pair oxygen electrons in conjugation with the pyrromethene chromophore of the natural product.

Ice nanoclusters at hydrophobic metal surfaces.

Studies of the structure of supported water clusters provide a means for obtaining a rigorous molecular-scale description of the initial stages of heterogeneous ice nucleation: a process of importance to fields as diverse as atmospheric chemistry, astrophysics and biology. Here, we report the observation and characterization of metal-supported water hexamers and a family of hydrated nanoclusters--heptamers, octamers and nonamers--through a combination of low-temperature scanning tunnelling microscopy experiments and first-principles electronic-structure calculations. Aside from achieving unprecedented resolution of the cyclic water hexamer--the so-called smallest piece of ice--we identify and explain a hitherto unknown competition between the ability of water molecules to simultaneously bond to a substrate and to accept hydrogen bonds.

QRS score improves diagnostic ability of treadmill exercise testing in women.

Objective: The accuracy of treadmill exercise testing to detect coronary artery disease is limited in women. This study was undertaken to evaluate whether QRS score can improve the accuracy of treadmill exercise testing in women.

Methods: The study population consisted of 114 women with angina-like symptoms, who underwent both treadmill exercise testing and coronary angiography.

"Textbook" adsorption at "nontextbook" adsorption sites: halogen atoms on alkali halide surfaces.

Density-functional theory and second order Møller-Plesset perturbation theory calculations indicate that halogen atoms bond preferentially to halide substrate atoms on a series of alkali halide surfaces, rather than to the alkali atoms as might be anticipated. An analysis of the electronic structures in each system reveals that this novel adsorption mode is stabilized by the formation of textbook two-center three-electron covalent bonds. The implications of these findings to, for example, nanostructure crystal growth, are briefly discussed.

Hypertensive patients with false-positive thallium-201 scintigraphic results in the infero-posterior wall are in high risk for coronary artery disease development.

Background: It has been previously postulated that Thallium-201 (Tl201) scintigraphy is characterized by relatively low specificity in hypertensive patients. This study was undertaken to assess any possible influence of false-positive scintigraphic results on the prognosis of hypertensive patients.

Methods: The study group comprised 179 consecutive hypertensive patients (128 men and 51 women), aged 50+/-7 years, who underwent exercise Tl(201) scintigraphy and coronary angiography (patients with normal scintigraphic results underwent coronary angiography due to persistent angina-like symptoms).

Significance of QRS duration changes in the evaluation of ST-segment depression presenting exclusively during the postexercise recovery period.

Background: The aim of this study was to evaluate the contribution of QRS prolongation in the diagnosis of coronary artery disease (CAD) in patients with exercise-induced ST-segment depression exclusively during the recovery period.

Methods: The study population consisted of 107 patients (90 males and 17 females) aged 39-70 (mean 59 +/- 7) years who underwent a treadmill exercise test using Bruce protocol and presented ST-segment depression limited to the recovery period. Angiographic data were available for all studied patients.

The aortic distensibility alteration is an index of influence of ischemic preconditioning to myocardial performance.

Background: Ischemic preconditioning (IP) is a cardioprotective phenomenon, induced by brief episodes of myocardial ischemia, which is supposed to affect not only the myocardium, but also the entire cardiovascular system. Considering that patients with coronary artery disease (CAD) have also been described to present impaired aortic mechanical properties, we tried to investigate the possible influence of the late phase of IP on aortic distensibility in patients with CAD.

Methods: Fifty patients, aged 48 to 72 (mean, 57+/-6 years), with angiographically confirmed CAD and exercise-induced myocardial ischemia, underwent two treadmill exercise testings (ETs).

Revisiting the structure of the p(4 x 4) surface oxide on Ag(111).

Scanning tunneling microscopy (STM) and density-functional theory are used to reexamine the structure of the renowned p(4 x 4)-O/Ag(111) surface oxide. The accepted structural model [C. I.

Role of right-sided chest leads in the detection of multivessel coronary artery disease in patients with extended Q-wave anterior myocardial infarction.

Objective: To evaluate the improvement of diagnostic ability of exercise testing to detect multivessel coronary artery disease in patients with extended Q-wave anterior myocardial infarction, using additional right-sided chest leads.

Methods: Fifty-two consecutive patients with Q-wave anterior myocardial infarction underwent exercise testing, using the standard 12 and the additional right-sided (V3R, V4R, V5R) chest leads, thallium-201 scintigraphy and coronary arteriography.

Results: Twenty-one (40%) patients had one-vessel disease, 18 (35%) had two-vessel disease and 13 (25%) had three-vessel disease.

Prevalence of asymptomatic coronary artery disease in men with vasculogenic erectile dysfunction: a prospective angiographic study.

Objectives: Erectile dysfunction (ED) shares common risk factors with coronary artery disease (CAD). It has been suggested that ED may be considered a clinical manifestation of a generalized vascular disease affecting also the penile arteries. The aim of this prospective study was to evaluate angiographically the incidence of asymptomatic CAD in men with ED of vascular origin.

The prognostic value of a QRS score during exercise testing.

Background: Values of a QRS score have been positively related to the number of narrowed coronary arteries and to the extent of myocardial ischemia in radionuclide imaging techniques.

Hypothesis: This study was conducted to evaluate the potential prognostic information of abnormal values of this QRS score during treadmill exercise testing in patients with established coronary artery disease (CAD).

Methods: In all, 309 patients (258 men, 51 women, mean age 56.

Effect of donor selection on the early outcome of heart transplant recipients.

Recipients receiving heart transplants from 83 donors from 1995 to 2002 were analyzed to evaluate the effect of various donor factors on recipient outcomes. The 83 donors (13 women and 70 men; 2-51 years old) had cold ischemic times ranging between 55 and 287 minutes. Donor age, cause of death, inotropic support, and cold ischemic times of the hearts were compared to 1-year left ventricular ejection fraction, permanent pacemaker dependency, 30-day mortality, and 1-year survival in the recipients.

QRS score versus ST-segment changes in patients undergoing Tl-201 scintigraphy using dipyridamole infusion.

Background: ST-segment changes after dipyridamole infusion followed by handgrip isometric stress lack diagnostic value, because of the low sensitivity for the detection of coronary artery disease (CAD). In addition, an abnormal QRS score during exercise had a greater diagnostic ability than ST-segment changes to detect CAD. This study was undertaken to compare QRS score values with ST-segment changes during thallium 201 scintigraphy via dipyridamole infusion.

Exercise testing in asymptomatic patients with heterozygous familial hypercholesterolaemia.

Objective: Familial hypercholesterolaemia (FH) is a frequent genetic disorder in Europe, affecting one in 500 people in its heterozygous form. Both homozygous and heterozygous forms are correlated with increased incidence of cardiovascular events.

Methods: We investigated clinical and biochemical parameters possibly associated with the results of exercise testing (ET) in asymptomatic patients with heterozygous FH.