Stereoselective Synthesis and Antiallodynic Activity of 3-Hydroxylated Paroxetines

The design, stereoselective synthesis and in vivo antiallodynic activity of four novel paroxetine analogs, named 3-hydroxy paroxetines (3HPXs), is reported herein. Among the novel synthesized compounds, three showed an antiallodynic effect, while (R,R)-3HPX was found to be 2.5 times more bioactive than (-)-paroxetine itself in neuropathic rats. Consequently, the current investigation not only discloses a novel promising analgesic drug, but also reveals that functionalization at the C3 position of paroxetine could be as effective as the common functionalization at either C4 or within the sesamol group.     

The isothermal section of the La–Si–Mg system at 500 C

The isothermal section of the La–Si–Mg system at 500 ^°C was constructed in the whole concentration range by means of the SEM-EDXS and XRPD characterization of about forty alloys prepared by induction melting and then annealed. Phase equilibria are characterized by the following ternary phases: τ₁-La_2+xSi₂Mg_1−x (0≤x≤0.35,tP10-Mo₂FeB₂), τ₂-LaSi₂Mg₂ (tP5-CeSi₂Mg₂), τ₃-LaSi₂Mg (structure still unknown) and τ₄-La₆SiMg₂₃ (cF120-Zr₆SiZn₂₃). The high temperature binary phase LaMg₂ (cF24-MgCu₂) has been found to be stabilized at 500 ^°C probably by a small amount of Si. Phases in binary subsystems do not generally form extended ternary solid solutions except for (La_1−xMg_x)₃Si₂ (0≤x≤0.167,tP10-U₃Si₂). Crystal structures of phases τ₁-La_2+xSi₂Mg_1−x and (La_1−xMg_x)₃Si₂ are correlated, the former being a substitution derivative of the latter.     

Stability of the passive state of Zr–Nb crystalline alloys

Stability of the passive state was assessed for pure Zr and four Zr–Nb alloys (2.5, 5.0, 10.0, 25.0 at.% Nb) after 24 h exposure to naturally aerated 3.5% NaCl solution (pH = 6). Open circuit potential values indicated that all the Zr–Nb alloys studied and the pure Zr undergo spontaneous passivation due to spontaneously formed oxide film passivating the metallic surface. It also indicated that the addition of increasing Nb contents to pure Zr seems to improve the protection characteristics of its spontaneous oxides. Potentiodynamic polarization curves showed an increase of the breakdown potential and the extent of the passive range following an increased niobium amount in the alloy. This leads to the conclusion that a progressive increase of niobium content positively affects the localized corrosion behaviour of the Zr–Nb alloys by enhancing the electrochemical stability of the passive film. Electrochemical impedance spectroscopy (EIS) studies showed high impedance values for all the samples, and its increase on increased niobium content in the alloy indicated an improvement in the corrosion resistance of the spontaneous oxide film. The fit obtained suggests a single passive film present on the metal surface, with resistance improving with the increase of niobium amount in the alloy. All these electrochemical results show the beneficial effect of increasing niobium contents on the passive state stability of the Zr–Nb alloys.     

Coding procedures to analyse interaction patterns in educational web forums

Analysis of interaction patterns is one of the most important indicators of quality of learning in educational web forums. Social network analysis (SNA) is gradually assuming importance in the study of interaction patterns as it focuses on the analysis of the interrelationships between individuals, thus providing a holistic perspective on group performance. However, most of the studies that use SNA in computer-supported collaborative learning scenarios derive their data from server log files, on the assumption that this data source reflects the way people really interacted online. This study, the purpose of which is to better understand the communication flows that really occur among users, challenges these assumptions through an experimental study that makes a comparison between the structural method normally used to detect the posting addressees and an approach enriched with semantic coding. Results show that this new coding schema, if compared with traditional structural coding, detected a greater number of addressees, thus allowing a greater number of postings to be included in an SNA adjacency matrix.     

Lightning return stroke current identification via field measurements

 An inverse procedure is presented for identifying and reconstructing the waveform of the lightning return stroke current. It is based only on the acquisition of the electromagnetic field radiated by the discharge channel in various locations on the ground and at various frequencies, and requires no information about the channel base current. The fundamental idea is shown to come from an electrostatic problem in which the linear charge density of a vertical thin wire is determined starting from the measured field. Three versions of this procedure have been developed: in the first, the identification is carried out by means of the measurement of the electric field at various distances from the lightning channel at a given frequency; in the second, only two sensors for the electric field are necessary, but various sampling frequencies; in the third, only one observation point is needed, for the measurement of both the electric and the magnetic field. A simulated validation of all the approaches is provided as well as a detailed analysis of their numerical accuracy. Received: 4 April 2001/Accepted: 30 April 2001     

Angiotensin-converting enzyme gene polymorphism and reversibility of uremic left ventricular hypertrophy following long-term antihypertensive therapy

BACKGROUND: Prolonged antihypertensive therapy might be less effective in reversing the left ventricular hypertrophy (LVH) in uremics bearing the deleted (DD) allele of the angiotensin converting enzyme (ACE) gene than in patients with the inserted (II) allele or in those heterozygous (ID) for the gene. METHODS: Thirteen DD and 17 II + ID hemodialyzed uremics were followed-up with yearly echocardiography and 24-hour blood pressure (BP) monitoring over five years while on an antihypertensive therapy that included ACE inhibitors as first line drugs. RESULTS: In the II + ID group there were significant decreases of the left ventricular mass index (LVMi) and of both systolic and diastolic BPs. These changes were less pronounced in the DD group, but the difference was not statistically significant given the wide overlap between the two groups. Further analysis of the data revealed that the only factor associated to a decreased LVMi was the decrease of the systolic BP irrespective of the ACE gene genotype of each individual patient. CONCLUSIONS: The ACE-gene genotype does not necessarily predict the extent to which LVMi will be lowered by ACE-inhibitors therapy. The LVH of hypertensive uremics is amenable by long-term antihypertensive therapy provided that it results in significantly decreased systolic blood pressure.     

Theoretical study of work function of conducting single-walled carbon nanotubes by a non-relativistic field theory approach

We study a non-relativistic many-fermion system on a small cylindrical surface. The interaction between the fermions is modeled as an attractive two-body contact effective potential, which allows binding of fermions on the cylinder surface. The N-fermion model is solved in a self-consistent Hartree-Fock (HF) approximation, and is applied to study the electronic properties of metallic single-walled carbon nanotubes (SWCNT). The many-fermion HF approach with contact interactions is known to mimic a first order density functional theory. We derive an analytic form of the SWCNT work function (WF), that is parameterized by the Fermi kinetic energy, and reproduces the graphene work function for large radius (R). This model allows us to understand theoretically the small experimental WF fluctuations and the non-trivial left-right asymmetry of the graphene WF distribution found experimentally in a large set of SWCNT with radius above 5 Å. By extending our model for SWCNT with very small radius, we found a WF that increases linearly with 1/R.     

Smoking and moods in adolescents with depressive and aggressive dispositions: Evidence from surveys and electronic diaries.

Surveys and electronic diaries were used to examine depressive and externalizing dispositions as they relate to smoking and moods in 170 early adolescents. Negative moods were prevalent, with anger and anxiety reported on 26%–60% and sadness on 16%–40% of occasions. The risk of smoking, urges to smoke, and alcohol intake were elevated in teens with aggressive and depressive dispositions, as were diary reports of feeling hassled, angry, and sad. Girls high in depression and aggression also reported more anxiety, stress, and fatigue and less happiness and well-being than did their peers. For boys, depression seemed to dampen the elevated smoking risks associated with externalizing behaviors. Discussion focuses on gender differences in personality–smoking linkages, adolescent negative affectivity, the unique contributions of survey and diary methods, and the promise of targeted preventive interventions such as affect regulation training. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Nucleation Processes Close to the Spinodal

Using an analytical equation of state (EOS) which describes a system that can exist in a liquid or vapor phase, a generalized Landau free-energy expansion around any spinodal point is constructed. For this simple model, the critical exponents associated with the spinodal line are obtained, and the model reduces to the usual expansion around the critical point as a particular case. The approach may become an interesting starting point to study phase separation mechanisms, such as nucleation and spinodal decomposition, far from the critical point. The decay of deeply quenched metastable states close to the spinodal through a nucleation process is analyzed and their mean lifetime is obtained. The results are compared with those obtained through the use of the usual Landau free-energy expansion around the critical point.