Reversible intercalation of aluminium into vanadium pentoxide xerogel for aqueous rechargeable batteries

Rechargeable batteries based on the intercalation of aluminium ions may be competitive against lithium-ion batteries, but their development and comprehension are full of difficulties.

Electrochemical and chemical insertion/deinsertion of magnesium in spinel-type MgMn2O4 and lambda-MnO2 for both aqueous and non-aqueous magnesium-ion batteries

A veritable magnesium-ion battery is described. Magnesium-ion can be reversibly extracted from MgMn₂O₄ and reversibly inserted into lambda-MnO₂.

On-line thermal dependence study of the main solar cell electrical photoconversion parameters using low thermal emission lamps

This paper presents a non-conventional methodology and an instrumental system to measure the effect of temperature on the photovoltaic properties of solar cells. The system enables the direct measurement of the evolution of open-circuit voltage and short-circuit current intensity in relation to a continuously decreasing temperature. The system uses a high-intensity white light-emitting diode light source with low emissions of radiation in the infrared region of the electromagnetic spectrum, resulting in a reduced heating of the photovoltaic devices by the irradiation source itself. To check the goodness of the system and the methodology designed, several measurements were performed with monocrystalline silicon solar cells, dye-sensitized solar cells, and thin-film amorphous silicon solar cells, showing similar tendencies to those reported in the literature.

Experimental analysis and computer simulation of a methodology for laser focusing in the solar cell characterization by laser beam induced current

This paper presents a quick methodology for focusing a laser beam on a photoactive surface based on performing a single line scan while simultaneously modifying the laser's position over the surface and the distance between the focusing lens and the active surface. The methodology was tested using the computer simulation technique. Several configurations were computer simulated by programming different experimental situations to discover the situations in which this focusing methodology would provide optimum results. The conclusions obtained from computer simulation methodology were checked by means of experimental tests using several solar cells, such as a thin-film amorphous silicon solar cell, a monocrystalline silicon solar cell, and a polycrystalline silicon solar cell. From the tests performed, we concluded that optimum focusing is achieved in systems in which the laser beam induced current signal generated by the photoactive surface has no large heterogeneities (e.g., fingers or grain boundaries), artefacts, or defects. Thus, the best results are achieved in systems where the surface of the photovoltaic device has a certain degree of homogeneity.

High resolution laser beam induced current images under trichromatic laser radiation: approximation to the solar irradiation

A laser beam induced current (LBIC) map of a photoactive surface is a very useful tool when it is necessary to study the spatial variability of properties such as photoconverter efficiency or factors connected with the recombination of carriers. Obtaining high spatial resolution LBIC maps involves irradiating the photoactive surface with a photonic beam with Gaussian power distribution and with a low dispersion coefficient. Laser emission fulfils these characteristics, but against it is the fact that it is highly monochromatic and therefore has a spectral distribution different to solar emissions. This work presents an instrumental system and procedure to obtain high spatial resolution LBIC maps in conditions approximating solar irradiation. The methodology developed consists of a trichromatic irradiation system based on three sources of laser excitation with emission in the red, green, and blue zones of the electromagnetic spectrum. The relative irradiation powers are determined by either solar spectrum distribution or Planck's emission formula which provides information approximate to the behavior of the system if it were under solar irradiation. In turn, an algorithm and a procedure have been developed to be able to form images based on the scans performed by the three lasers, providing information about the photoconverter efficiency of photovoltaic devices under the irradiation conditions used. This system has been checked with three photosensitive devices based on three different technologies: a commercial silicon photodiode, a commercial photoresistor, and a dye-sensitized solar cell. These devices make it possible to check how the superficial quantum efficiency has areas dependent upon the excitation wavelength while it has been possible to measure global incident photon-to-current efficiency values approximating those that would be obtained under irradiation conditions with sunlight.

Cation order/disorder in lithium transition-metal oxides as insertion electrodes for lithium-ion batteries

Results on the local cation ordering in layered lithium-nickel/cobalt oxides and metal-substituted lithium-manganese spinels are presented. It is shown that electron spin resonance of Ni3+ and Mn4+ and magnetic susceptibility measurements are powerful tools to monitor the short-range cation ordering in these compounds, which is not accessible by diffraction techniques. Thus, owing to the different strength of the 90° and 180° Ni3+–O–Ni3+/2+ exchange interactions, the distribution of Ni3+/Ni2+ between the lithium and nickel layers in Li1–xNi1+xO2 with 0 < x < 0.4 can be determined. For layered LiNi1–yCoyO2 and spinel LiMn2–xCoxO4 solid solutions, analysis of the temperature-independent EPR line width in terms of dipole–dipole and exchange interactions has been used to examine the local Ni3+/Co3+ and Mn4+/Co3+ ordering. The results obtained are correlated with the electrochemical intercalation of lithium in these compounds.

Theoretical study of the morphologically originated noise associated with the transmittance of a precipitation system

In this paper we present the results of a computational study that analyses the relationship between the noise associated with the optical transmittance of a system of particles and the morphology of such particles. Computational algorithms have been developed in order to represent the different morphologies within a wide range of sizes. By using this methodology, it has been possible to study the morphology of particles in a virtual system, therefore avoiding the distortions that would inevitably be present in a real system. As a consequence of this study, a classification of the morphologies observed has been made according to the amount of noise they would add to the transmittance of a system of particles. The theoretical results obtained are in good agreement with the available experimental data obtained in real systems.

[Acute hepatitis due to ticlopidine. A report of 12 cases and review of the literature]

OBJECTIVE

To analyze the characteristics of hepatotoxicity due to ticlopidine.

PATIENTS AND METHODS

We describe all the case of hepatotoxicity attributed to ticlopidine and reported to the Register of drug associated hepatopathies. We also obtained data from MEDLINE and the Spanish Medical Index regarding cases reported during the period 1982 2001.

RESULTS

We reported twelve cases of hepatopathy related to the use of ticlopidine. These made up 5% of all the cases notified to the Register. Eighty three percent of the patients were male, and of an average age of 68 years. Sixty six percent required hospital admission. The latent period varied between 2 and 13 weeks. The liver lesion was of cholestatic type in 75% of the cases, hepatocellular in 16.6% and mixed in 8.3%. Twenty five percent of the patients had received sub therapeutic doses.

CONCLUSIONS

Ticlopidine is often related to hepatotoxicity. This seems to be due to an idiosyncratic mechanism and is mainly cholestatic. The use of lower dosage than that recommended means that the desired therapeutic effect is not attained but does not protect against the development of hepatotoxicity. Doctors who use this drug should be aware of this so as to establish the true risk benefit relation.

Analysis and localization of epileptic events using wavelet packets

This article compares results obtained in previous studies using time-frequency representations (Wigner-Ville, Choi-Williams and Parametric) and the wavelet transform with those obtained with wavelet packet functions to show new findings about their quality in the analysis of ECoG recordings in human intractable epilepsy: data from 21 patients have been analyzed and processed with four types of wavelet functions, including Orthogonal, Biorthogonal and Non-Orthogonal basis. These functions were compared in order to test their quality to represent spikes in the ECoG. The energy based on the wavelet coefficients to different scales was also calculated. The best results were found with the biorthogonal-6.8 wavelet on 5-7 scales, which gave 0.92 sensitivity, but with a high percentage of false positives; this representation was highly correlated with spike events on time and duration. To improve these results we have studied the wavelet packet coefficients energy. We found that reconstruction wavelet packet coefficients at 4 and 9 nodes contain significant information to characterize the spike event. These nodes' reconstruction coefficients were multiplied and this product was highly correlated with spikes events on time and duration. With this procedure we improved the sensitivity up to 0.96 with the same biorthogonal-6.8 wavelet at four levels. With this technique we do not sacrifice computation time: 896 samples are processed at only 0.16 s, so that it is possible to show the spike scattering path on line, because 896 samples (7 s)/16 channels are processed at 3.13 s.

Experimental study of precipitating systems; computerised analysis of the optical transmittance and associated noise

The change of the transmittance in a precipitant system has been measured by using a focused laser beam into a precipitation cell in which the precipitate was generated by an injection technique. We have monitored the evolution of the transmittance on several precipitation processes with different chemicals (PbI2, PbSO4, BaSO4 and BaC2O4) and quantities of precipitated mass (20.0, 17.5, 15.0, 12.5 and 10.0 mg). The noise associated to the transmittance signal has been obtained by a numerical procedure based on computer analysis, finding that it provides information about particle shape features and nucleation kinetics.

Study of precipitant systems by computerised simulation. Influence of optical elements on the noise associated with the transmittance

The transmittance signal of a precipitant system measured with a focused laser beam carries associated noise coming from several sources. In this work, we have studied the influence of the focal parameters (wavelength, focal length and prefocused radius of the beam) on the maximum noise reached in equivalent nucleation processes. For this purpose, a simulation program of precipitating systems, designed in FORTRAN 90, has been developed. The program generates simulated transmittances, which are processed by another computer program to extract associated noise. Wide ranges of values of the focal parameters have been analysed, finding relationships between the maximum noise and the focal parameters. They have been justified in connection with the changes observed in the radial parameters, which define the size and shape of the focused path.

Flutamide-induced hepatotoxicity: report of a case series

OBJECTIVE

To evaluate the characteristics of flutamide induced hepatotoxicity.

MATERIAL AND METHODS

In this retrospective study we have analyzed all cases of flutamide hepatotoxicity submitted to the Andalucian Registry of drug-induced liver disease. Data were collected using a structured reporting form. Causality assessment was performed using two clinical scales: the standard CIOMS scale and the recently developed María and Victorino scale.

RESULTS

Nine of 185 patients (4.9%) were identified. In 8 male patients, mean age 75 years (range 65-83), flutamide was indicated for palliative therapy of disseminated prostatic carcinoma, and in one young female (14 years) was given for the treatment of facial hirsutism. The mean duration of the flutamide therapy was 151 days (range 4-443). All patients presented with overt liver injury, the most frequent features being asthenia, anorexia, weight loss, nausea, vomiting and jaundice. No patient showed hypersensitivity features. In two patients (22%) the hepatic damage evolved to fulminant liver failure, one of them undergoing a liver transplantation and the other subsequently died. An additional patient died of a non-hepatic related cause when his liver function was improving. Causality assessment by the two clinical scales did not exclude any case, but the two patients who died where classified as unlikely by the María and Victorino scale.

CONCLUSIONS

Flutamide can induce severe acute hepatitis, probably due to an idiosyncratic metabolic mechanism. Liver tests monitoring should probably be mandatory during the first months of flutamide therapy and the drug withdrawn if transaminases began to increase.

Chronic liver injury related to use of bentazepam: an unusual instance of benzodiazepine hepatotoxicity

Liver injury induced by benzodiazepines is rare and is classified as an unpredictable or idiosyncratic hepatotoxic reaction. Early reports indicated that in most cases the pattern of liver injury was cholestatic. We describe three patients with persistent increases in liver transaminase levels after several weeks of treatment with bentazepam, a benzodiazepine marketed in Spain for anxiety disorders. In all cases withdrawal of the drug was followed by resolution of transaminase level abnormalities. A liver biopsy (done in one patient only) showed histological evidence of severe chronic active hepatitis. In conclusion, these findings, together with two previously published case reports, suggest that a benzodiazepine can cause chronic hepatitis and argue in favor of using liver function tests to monitor all patients taking bentazepam.

Effects of interferon-beta on plasma lipid and lipoprotein composition and post-heparin lipase activities in patients with chronic hepatitis C

BACKGROUND

Interferon therapy has been shown to induce lipid abnormalities.

AIM

We assessed the effects of interferon-beta on the lipoprotein profile and post-heparin lipase activities in 26 normolipaemic patients with chronic hepatitis C.

METHODS

Interferon-beta was administered subcutaneously at doses of 6 x 106 U (units) three times a week, over 6 months, and lipoproteins and post-heparin lipases were measured at baseline and at the end of therapy.

RESULTS

Plasma triglycerides increased by 21% due to preferential enrichment in those contained in the very low density lipoprotein (VLDL) and low density lipoprotein (LDL) fractions. The concentration of cholesterol decreased slightly in the high density lipoprotein (HDL) subfractions. Lipoprotein lipase, but not hepatic lipase activity decreased by a 36%, and this change showed a significant negative correlation with changes in plasma triglycerides. Five patients (19.5%) responded to interferon-beta therapy. The lipoprotein profile was no different between responders and non-responders to therapy.

CONCLUSIONS

Interferon-beta treatment in normolipaemic patients with chronic hepatitis C induced moderate disturbances in plasma lipoproteins, associated with inhibition of lipoprotein lipase activity.

[HELLP syndrome. Analysis of 2 cases]

HELLP syndrome (Hemolysis, Elevated Liver Enzymes, Low Platelets), one of the gestational diseases of the third trimester of pregnancy associated to eclampsia or preeclampsia, has a varied clinical expression, that include poor symptomatic patterns with malaise and/or dyspepsia, even several patterns with fatal outcome. We show two cases with clinical and laboratory criterion of HELLP syndrome, but with different clinical presentations. It's analyzed the pathogenicity, clinical-pathological expression, course and therapeutics options in HELLP syndrome.

[Chronic cholestasis as a presentation form of portal cavernoma]

A 37 year-old-woman was evaluated in 1993 for a chronic asymptomatic cholestasis. An endoscopic retrograde cholangiopancreatography showed the biliary tract compressed, and a mesenteric angiogram disclosed that the cause of biliary obstruction was a portal cavernoma. In addition, large esophageal varices with "red spots" were observed at endoscopy. Propranolol and ursodeoxicolic acid were started and the patient has remained asymptomatic to date. The biliary features of portal cavernoma are reviewed, as well as its pathogenesis, diagnosis and management. Portal cavernoma should be considered in the differential diagnosis of chronic cholestasis.

[Chronic asymptomatic intrahepatic cholestasis associated with Turner's syndrome]

Turner syndrome or the gonadal dysgenesis syndrome which is monosomic because of the lack of an X chromosome (45 X) is associated to a greater incidence of autoimmune, particularly thyroidal, disorders and inflammatory intestinal disease, but is rarely associated to hepatic disorders. A female patient with chronic asymptomatic intrahepatic cholestasis which, to our knowledge, is the first reported in Spain, is herein presented. The 40-year old patient with a 45 X karyotype, feminine phenotype was accidently found to have a chronic alteration in the hepatic profile. Hepatic biochemical tests revealed AST 59 U/L, ALT 90 U/L, GGT 201 U/L and alkaline phosphatase 320 U/L. Hepatic echography was normal. Percutaneous liver biopsy was performed demonstrating minimum changes consisting of sinusoidal dilatation and pigment accumulation in the hepatocyte biliary pole. Treatment with ursodeoxycholic acid 15 mg/kg/day was administered showing a marked decrease in the laboratory parameters during follow up. Different hypothesis which may explain the association between chronic asymptomatic intrahepatic cholestasis and Turner syndrome are discussed.

Hydrodynamic properties and immunological identification of the sodium- and chloride-coupled glycine transporter

We have recently reported the purification of the native sodium- and chloride-coupled glycine transporter from pig brain stem (López-Corcuera, B. Vázquez, J., and Aragón, C. (1991) J. Biol. Chem. 266, 24809-24814). This preparation is essentially homogeneous and contains a unique 100-kDa polypeptide based on electrophoretic migration under denaturing conditions. In this paper we report the hydrodynamic characterization of the native transporter, solubilized in two different detergents, as well as the immunological identification of the protein. On the basis of results obtained from size-exclusion chromatography, we calculated the Stokes radii of transporter 3-[(3-cholamidopropyl)dimethylammonio]-1-propanesulfonic acid (CHAPS) and transporter-cholate complexes to be 5.5 and 6.0 nm, respectively. In addition, from H2O/D2O sucrose density gradient sedimentation analysis, we calculated the molecular weight of protein-detergent complexes to be 115,000 and 160,000 in CHAPS and cholate, respectively, and the molecular weight of the protein moiety as 86,000. Finally, polyclonal antibodies raised against the 100-kDa polypeptide were found to immunoprecipitate specifically glycine transport activity. Taken together, the results reported herein corroborate the identity of the 100-kDa band as the sodium- and chloride-coupled glycine transporter and also suggest that in its native state the transporter is a monomeric protein.

L-glutamate transporter derived from mRNAs of primary glial cultures: expression in Xenopus laevis oocytes

A high-affinity sodium-dependent L-glutamate transporter was expressed in Xenopus oocytes after microinjection of poly(A)+ RNA from primary astrocyte cultures from rat brain cortex. mRNA-induced L-glutamate transport was saturable by substrate and shows kinetic features similar to those found in intact glial cell preparations. L-Glutamate accumulation was prevented by rising the external K+ concentration or by coincubation with L-, D-aspartate or D-glutamate. After fractionation by sucrose density gradient, the mRNA encoding for the expressed L-glutamate transporter from glial cells was found in fractions containing messages of 2.05-2.9 kilobases (kb) in length.

Group-selective reagent modification of the sodium- and chloride-coupled glycine transporter under native and reconstituted conditions

Glycine transporter from rat brain stem and spinal cord is inactivated by specific sulfhydryl reagents. Modification of lysine residues also promotes a decrease of the transporter activity but in a lesser extent than that promoted by thiol group reagents. Mercurials showed a more marked inhibitory effect than maleimide derivatives. SH groups display a similar reactivity for p-chloromercuribenzenesulfonate (pCMBS) and mersalyl in synaptosomal membrane vesicles and proteoliposomes reconstituted with the solubilized transporter. However, different reactivity is observed with N-ethylmaleimide (MalNEt), the greatest effect being attained in membrane vesicles. The rate of inactivation by pCMBS and MalNEt is pseudo-first-order showing time- and concentration-dependence. pCMBS and MalNEt decrease the Vmax for glycine transport and to a lesser extent act on the apparent Km. Treatment with dithiothreitol (DTT) of the transporter modified by pCMBS results in a complete restoration of transporter activity indicating that the effect exercised by the reagent is specific for cysteine residues on the protein. It is concluded that SH groups are involved in the glycine transporter function and that these critical residues are mostly located in a relatively hydrophilic environment of the protein.