Chemical composition, mineral content and antioxidant activity of Verbena officinalis L.

Aqueous and hydroalcoholic extracts from Verbena officinalis L. were obtained and characterised. The analysis by HPLC-DAD and LC-MS allowed the detection and identification of three iridoids, fifteen flavonoids and four phenolic acid derivatives. Four flavonoids, scutellarein 7-diglucuronide (9), scutellarein 7-glucuronide (13), pedalitin 6-galactoside (15) and scutellarein 7-glucoside (19) are reported for the first time from this plant. In addition, three new flavonoids have been isolated: scutellarein 7-O-(2-O-feruloyl)-diglucuronide (5), pedalitin 6-O-diglucuronide (6) and pedalitin 6-O-(2-O-feruloyl)-diglucuronide (13). To our knowledge, these flavonoids have not been reported as natural products. Both extracts showed significant antioxidant activity using three in vitro model systems and the results have been correlated with total phenolic and total flavonoid contents. The results have allowed establishing an important relation structure-activity and significant correlations have also been found between the mineral content and the flavonoids present in both extracts.     

Nafion/polyaniline/silica composite membranes for direct methanol fuel cell application

This work investigates the characterization and performance of polyaniline and silica modified Nafion membranes. The aniline monomers are synthesized in situ to form a polyaniline film, whilst silica is embedded into the Nafion matrix by the polycondensation of tetraethylorthosilicate. The physicochemical properties are studied by means of X-ray diffraction and Fourier transform infrared techniques and show that the polyaniline layer is formed on the Nafion surface and improves the structural properties of Nafion in methanol solution. Nafion loses its crystallinity once exposed to water and ethanol, whilst the polyaniline modification allows crystallinity to be maintained under similar conditions. By contrast, the proton conductivities of polyaniline modified membranes are 3–5-fold lower than that of Nafion. On a positive note, methanol crossover is reduced by over two orders of magnitude, as verified by crossover limiting current analysis. The polyaniline modification allows the membrane to become less hydrophilic, which explains the lower proton conductivity. No major advantages are observed by embedding silica into the Nafion matrix. The performance of a membrane electrode assembly (MEA) using commercial catalysts and polyaniline modified membranes in a cell gives a peak power of 8 mW cm⁻² at 20 °C with 2 M methanol and air feeding. This performance correlates to half that of MEAs using Nafion, though the membrane modification leads to a robust material that may allow operation at high methanol concentration.     

Cyclic oxidation of copper doped Ti-48Al-2Cr-2Nb

The widespread use of titanium aluminide alloys will require effective joining techniques for primary fabrication and repair. One such technique is Transient Liquid Phase (TLP) bonding, which has been used to join titanium aluminide alloys. A successful TLP bonding process uses a copper-containing composite interlayer and thus introduces a small amount of copper into the alloy. Although even relatively small alloying additions can be detrimental to the oxidation resistance of titanium aluminide alloys, the amount of copper added to the alloy during the TLP bonding process has previously been shown to be neutral or beneficial to the isothermal oxidation resistance of the alloy. In this paper, a small amount of copper introduced during TLP bonding is shown to have no detrimental effect on the cyclic oxidation of Ti-48 at% Al-2 at% Cr-2 at% Nb.     

Infrared thermography (IRT) and ultraviolet fluorescence (UVF) for the nondestructive evaluation of ballast tanks’ coated surfaces

This paper quantifies the detectability limits of infrared thermography (IRT) and ultraviolet fluorescence (UVF) techniques in the thickness measurements of the naval protective coatings applied on ship ballast tanks. The change in signal per unit thickness (25 μm) is used to describe each technique resolution, when using a pulsed-thermographic procedure and a UVF spectroscopic analysis. Furthermore, Tanimoto criterion in addition to a local signal-to-noise ratio (SNR) computation measure the revealability of pinholes, the IRT technique provides an 83% revealability while the UVF imaging has a 66% value. The goal of this work is to benchmark the novel UVF approach against that of the IRT procedures.     

Follow-up of partial seizure progression in an infant

OBJECTIVE AND MATERIAL: We are carried out a retrospective study of 43 patients, 21 males and 22 women entered during the period of infancy in the Service of Neurology of our hospital and with diagnostic of any type of partial seizure, in an intent to correlate a series of clinical parameters, electroneurophysiologics and initial therapeutics with their factors follow-up periods. RESULTS: They are a half age of 7.11 months (1-19), consecutive being controlled for a period of time of 40 months (6-96). We have settled down a relationship between the drugs utilized in the first seizure and that other that they remained in their last revision, the current state of the critical manifestations, and the existence or not of an agreement between the e diagnosis emitted to the discharge and the development of the illness. CONCLUSION: After the present study, we thought that the current classification of the epileptic seizures is insufficient in the age of the infant, with presages much more complexes.     

Electrochemically promoted olefin isomerization reactions at polymer electrolyte fuel␣cell membrane electrode assemblies

The isomerization of 2-3-dimethyl-1-butene was enhanced over a thousand fold (vs the open circuit value) by spillover protons generated by low currents (electrochemical promotion) on carbon supported Pd catalysts in a polymer electrolyte fuel cell. There was substantial proton spillover catalyzed shift of the double bond of 2-3-dimethyl-1-butene. With 3-3-dimethyl-1-butene, the proton spillover catalyzed methyl shift occurred at low levels and 2-2-dimethyl-butane was the primary product from the simple reduction reaction. Although the substantial non-Faradaic electrochemical modification of catalysis (NEMCA) of the double bond isomerization of an olefin was further demonstrated, the more challenging electrochemical promotion of an olefin methyl shift at the polymer electrolyte Pd/C cathode was less pronounced.     

The role of endoscopic third ventriculostomy in the management of shunt malfunction

OBJECTIVE: To evaluate the effectiveness of third ventriculostomy as an alternative to shunt revision in the management of shunt malfunction and infection in obstructive hydrocephalus. METHODS: All of the clinical notes of 30 patients treated with third ventriculostomy for malfunctioning or infected shunts between January 1, 1974, and December 31, 1996, were retrospectively reviewed. Third ventriculostomy was performed under fluoroscopic control in the first seven patients and endoscopically in the remainder. A successful outcome was achieved if further shunt revision surgery was avoided. The median follow-up duration was 8.7 years RESULTS: Twenty-three patients (76.7%) experienced successful outcomes, resulting in shunt independence. Of the seven failures, three were technical failures at the time of surgery and the remaining four were manifest within a median of 10 days, resulting in shunt revision. There have been no delayed failures. CONCLUSION: Third ventriculostomy is a valuable alternative to shunt revision in patients affected by obstructive hydrocephalus presenting with shunt malfunction or infection. It should be considered in all suitable cases as the first-line treatment for obstructive hydrocephalus of all causes. Because all failures were manifest within a short time, it is likely that these successes will be durable.     

Hemodynamic evaluation in acute myocardial infarct. Application to the treatment of contractile insufficiency syndromes of the left ventricle

Even though the coronary care units have reduced to a minimum the mortality due to arrhythmias, the syndromes of left ventricular failure are responsible for the greatest part of hospital deaths in patients with acute myocardial infarction. The poor results depend upon the extensive destruction of left ventricular mass. The management in these cases should be directed to improve the performance of viable muscle as well as to preserve thejeopardized ischemic myocardium that is potentially viable. These goals may be adequately pursued by continuous hemodynamic characterization of left ventricular function. The experience of the Coronary Care Unit of the Instituto Nacional de Cardiología de México in the study of 30 of these patients is presented. Hemodynamic evaluations were performed by means of a Swan-Ganz catheter and cardiac output determinations by the thermodilution technique. The studies may be performed with a minimum of risk. Central venous pressure measurements do not adequately indicate the status of the left ventricle. Its function may be evaluated by the use of end diastolic pulmonary artery pressure which reflects, quite accurately, the left ventricular filling pressure in these patients. Continuous hemodynamic monitorization facilitates the proper manipulation of the determinants of ventricular performance (preload, afterload, cardiac rate and contractility) and permits an attempt to improve the balance between available oxygen and myocardial oxygen requirements. Hemodynamic studies and ventricular function curves are presented in selected patients with acute myocardial infarction. The mortality due to left ventricular failure and cardiogenic shock in patients with acute myocardial infarction remains extremely high. However, it is only through the early recognition by continuous hemodynamic monitorization and the aggressive management of the patient with incipient left ventricular failure that the number of survivors may be increased.     

Statistical Methods for Testing Quality of Communication Channels

The reliable transmission of information over communication channels depends greatly on the adequacy of the maintenance program provided for the transmission medium. An integral part of such a program is the procedure used for determining the quality of a communication link. In this concise paper, we discuss several statistical methods for ascertaining those impairments-and their respective levels-which reveal the most information about the fidelity of the channel in signal transmission. For the purpose of illustration, an example is presented which demonstrates how a testing program could implement each particular statistical method.     

Solid-state transformations during diffusion bonding of copper to iron

Solid-state bonding between dissimilar metals, produced at elevated temperatures with the application of a bonding pressure, causes structural changes in the microstructure of the zones nearest to the bond interface. These metallurgical transformations, produced by interdiffusion in the vicinity of the bond, decide the final properties of the joint. In the present paper, such diffusional transformations have been investigated for diffusion-bonded joints of Armco iron and copper with different oxygen contents (ETPC and OFLPC). The formation of iron oxide (wustite) has been observed in the ETPC-Armco iron joints. This oxide did not appear in OFLPC-Armco iron diffusion-bonded joints. This suggests that iron oxide forms by reaction of iron with oxygen dissolved in the ETPC base metal. The formation of copper particles in the iron base matrix, near the bond interface, has been observed. This may be due to two different processes: the solid-state precipitation of copper into iron and the eutectoid reaction (γ →ε +α) at bonding temperatures above 900° C.