Very-high-frequency oscillations in the main peak of a magnetar giant flare.

Magnetars are strongly magnetized, isolated neutron stars1-3 with magnetic fields up to around 1015 gauss, luminosities of approximately 1031-1036 ergs per second and rotation periods of about 0.3-12.0 s. Very energetic giant flares from galactic magnetars (peak luminosities of 1044-1047 ergs per second, lasting approximately 0.1 s) have been detected in hard X-rays and soft γ-rays4, and only one has been detected from outside our galaxy5. During such giant flares, quasi-periodic oscillations (QPOs) with low (less than 150 hertz) and high (greater than 500 hertz) frequencies have been observed6-9, but their statistical significance has been questioned10. High-frequency QPOs have been seen only during the tail phase of the flare9. Here we report the observation of two broad QPOs at approximately 2,132 hertz and 4,250 hertz in the main peak of a giant γ-ray flare11 in the direction of the NGC 253 galaxy12-17, disappearing after 3.5 milliseconds. The flare was detected on 15 April 2020 by the Atmosphere-Space Interactions Monitor instrument18,19 aboard the International Space Station, which was the only instrument that recorded the main burst phase (0.8-3.2 milliseconds) in the full energy range (50 × 103 to 40 × 106 electronvolts) without suffering from saturation effects such as deadtime and pile-up. Along with sudden spectral variations, these extremely high-frequency oscillations in the burst peak are a crucial component that will aid our understanding of magnetar giant flares.

Determination of selenium urinary metabolites by high temperature liquid chromatography-inductively coupled plasma mass spectrometry.

The coupling of high temperature liquid chromatography (HTLC) and inductively coupled plasma mass spectrometry (ICPMS) for the determination of selenium metabolites in urine samples is reported for the first time. In order to achieve "ICPMS-friendly" chromatographic conditions, the retention on a graphite stationary phase of the major selenium urinary metabolites using only plain water with 2% methanol as the mobile phase was investigated. Under the optimal conditions (T=80°C, Ql=1.2 mL min(-1)), methyl 2-acetamido-2-deoxy-1-seleno-ß-d-galactopyranoside (selenosugar 1), methyl 2-acetamido-2-deoxy-1-seleno-ß-d-glucosopyranoside (selenosugar 2) and trimethylselenonium ion were efficiently separated in less than 7 min, without any interferences due to other common selenium species (selenite, selenate, selenocystine and selenomethionine) or detectable effect of the urine matrix. The limits of detection were 0.3-0.5 ng Se mL(-1), and the precision of the analytical procedure was better than 3% (RSD%, n=5). The HTLC-ICPMS method was applied to the analysis of urine samples from two volunteers before and after ingestion of Brazil nuts or selenium supplements. The developed procedure proved to be adequate for the analytical task, providing results consistent with previous studies.

Simple and rapid analytical method for the simultaneous determination of cetrimonium chloride and alkyl alcohols in hair conditioners.

A simple method for the simultaneous determination of a cationic surfactant (cetrimonium chloride) and four non-ionic surfactants (1-tetradecanol, 1-hexadecanol, 1-octadecanol and 1-eicosanol) has been developed. Direct extraction of the analytes from the sample with methanol and a subsequent separation using reversed-phase high-performance liquid chromatography with refractive index detection are the steps followed in the procedure. The column used was a Luna C18 and the mobile phase consisted of a 0.1 M KClO(4) solution prepared on a 95:5 mixture of methanol and water. This solution was adjusted to pH 2.8 with phosphoric acid. Recoveries close to 100% were obtained in spiked commercial hair conditioner samples for the surfactants assayed using this method. Limits of detection were 10.4, 16.7 and 22.9 mg kg(-1) of cetrimonium chloride, 1-hexadecanol, 1-hexadecanol and 1-1-octadecanol respectively. The methodology was successfully applied to nine commercial hair conditioners of several types and different brands. All hair conditioners but one contained at least two of the surfactants included in this study.

[Quality of interaction database management systems]. / Calidad estructural de las bases de datos de interacciones.

OBJECTIVE: To identify drug interaction databases (DID) and assess the quality of their structures. METHOD: A search was made of the literature for DID and a series of exclusion and structural quality criteria were defined (at least four quality criteria: Classification according to severity, classification according to level of evidence, bibliographical reference data, description of clinical management and 11 criteria used for weighting). The level of compliance of every DID with the criteria defined was analysed, together with the level of compliance of each criteria in each DID. RESULTS: A total of 54 DID were identified, 30 of which complied with exclusion criteria and 15 of which did not meet the minimum criteria. The rest of the criteria were evaluated in nine DID: Bot-plus and Medinteract (100 %), SEFH Guide, Lexi-interact and Medscape (89 %), Hansten (83 %), Micromedex and Stockley (78 %), Drug Interactions Facts (68 %). Ninety-two per cent of the DID describe the mechanism of action, 87 % classify the information according to the active ingredient, 75 % do not state they have any conflict of interest, classify according to level of severity, have electronic format and are easy to search. A total of 67 % are specific DID, 62 % are classified according to level of evidence, contain bibliographical references and describe clinical management. CONCLUSIONS: A third of the DID comply with the minimum criteria. Differences were observed in the level and compliance criteria among Spanish and foreign DID. Some of the main DID used as references in the bibliography have significant structural defects: no web presentation, no multi-check function and others.

Calidad estructural de las bases de datos de interacciones / Quality of interaction database management systems

Objetivo: Identificar bases de datos de interacciones medicamentosas (BDIM) y valorar su calidad estructural. Método: Se realizó una búsqueda bibliográfica de BDIM y una definición de criterios de exclusión y calidad estructural (4 criterios de calidad mínima: estratificación según grado de gravedad, clasificación según nivel de evidencia, referencia bibliográfica de datos, descripción del manejo clínico, y 11 criterios que aportaban peso ponderal). Se analizó el grado de cumplimiento en cada BDIM de los criterios definidos y el grado de cumplimiento de cada criterio en todas las BDIM. Resultados: Se identificaron 54 BDIM de las que 30 cumplían criterios de exclusión y 15 no reunían criterios mínimos. Se valoró el resto de los criterios en 9 BSM: Bot-plus y Medinteract (100 %), Guía de la SEFH, Lexi-interact y Medscape (89 %), Hansten (83 %), Micromedex y Stockley (78 %), Drug Interactions Facts (68 %). El 92 % de las BDIM describen mecanismo de acción, el 87 % estructura la información por principio activo, el 75 % no declara tener conflicto de intereses, estratifica según grado de gravedad, tiene soporte informático y la búsqueda es ágil. El 67 % son BDIM específicas, el 62 % clasifica según nivel de evidencia, contiene referencias bibliográficas y describe el manejo clínico. Conclusiones: Un tercio de las BDIM cumplen criterios mínimos. Se encontraron diferencias en el grado y el criterio de cumplimiento entre las BDIM españolas y las de otros países. Algunas de las principales BDIM utilizadas como referentes en la bibliografía presentan importantes deficiencias estructurales: la falta de presentación web y de función multi-check y otras (AU)

Objective: To identify drug interaction databases (DID) and assess the quality of their structures. Method: A search was made of the literature for DID and a series of exclusion and structural quality criteria were defined (at least four quality criteria: Classification according to severity, classification according to level of evidence, bibliographical reference data, description of clinical management and 11 criteria used for weighting). The level of compliance of every DID with the criteria defined was analysed, together with the level of compliance of each criteria in each DID. Results: A total of 54 DID were identified, 30 of which complied with exclusion criteria and 15 of which did not meet the minimum criteria. The rest of the criteria were evaluated in nine DID: Bot-plus and Medinteract (100 %), SEFH Guide, Lexi-interact and Medscape (89 %), Hansten (83 %), Micromedex and Stockley (78 %), Drug Interactions Facts (68 %). Ninety-two per cent of the DID describe the mechanism of action, 87 % classify the information according to the active ingredient, 75 % do not state they have any conflict of interest, classify according to level of severity, have electronic format and are easy to search. A total of 67 % are specific DID, 62 % are classified according to level of evidence, contain bibliographical references and describe clinical management. Conclusions: A third of the DID comply with the minimum criteria. Differences were observed in the level and compliance criteria among Spanish and foreign DID. Some of the main DID used as references in the bibliography have significant structural defects: no web presentation, no multi-check function and others (AU)

Effect on composition of dry mechanical grinding of calcium phosphate mixtures.

For diverse reasons, calcium phosphates used to prepare hydraulic calcium phosphate cements can be ground mixed. The grinding with a rotating micromill of monocalcium phosphate monohydrate or anhydrous, dicalcium phosphate dihydrate or anhydrous with calcium oxide, calcium hydroxide, calcium carbonate, tetracalcium phosphate, or alpha- or beta-tricalcium phosphate was studied for different calcium to phosphate (Ca/P) ratios, rotating rates, masses of balls, and environmental conditions. During dry grinding by ball milling, anhydrous or hydrated acid calcium phosphates can mechanochemically react with anhydrous or hydrated basic calcium salts to form dicalcium phosphate dihydrate or anhydrous, noncrystalline calcium phosphate, and/or calcium deficient or stoichiometric hydroxyapatite, depending on the Ca/P ratio in the mixture and the time of grinding. The reaction rate is a function of the rotation rate and the mass of the balls. Water is not necessary to initiate the reaction but facilitates it because hydrated salts react faster than the corresponding anhydrous salts. Neither carbon dioxide nor carbonate ions seem to have any influence on the transformation kinetics. The transformations that occur during grinding influence the final mechanical properties of hydraulic calcium phosphate cements prepared from these materials. Thus, if a grinding step of the starting materials is planed, the grinding conditions will have to be particularly well defined to obtain reproducible results.

Effect of mechanical grinding of MCPM and CaO mixtures on their composition and on the mechanical properties of the resulting self-setting hydraulic calcium phosphate cements.

Calcium bis-dihydrogenophosphate monohydrate (or monocalcium phosphate monohydrate, MCPM) is often used as the acid calcium phosphate in hydraulic calcium phosphate cement formulations. But commercial MCPM is not pure; it contains a small amount of orthophosphoric acid and moisture. Consequently, MCPM is difficult to mill and the powder is sticky and presents aggregates. Because granularity influences the mechanical properties of the hardened cements, a possible way to get around this difficulty that has been proposed is to premix it with other materials before grinding. We therefore ground commercial MCPM with CaO. A rapid decrease in the amount of MCPM was observed during mechanical grinding by a solid-solid reaction with calcium oxide. The final products were anhydrous or dihydrate dicalcium phosphate and/or hydroxyapatite or calcium-deficient hydroxyapatite depending on the initial calcium-to-phosphate (Ca/P) ratio. The mechanical properties (compressive strength and setting time) of cements made from MCPM and CaO were affected whatever the Ca/P ratio as a consequence of the change in composition of the starting materials. Storage at different temperatures of MCPM and CaO mixtures manually ground in a mortar for only 2 min and without mechanical grinding did not affect their composition, but a decrease was observed in the compressive strength of cements made from these mixtures.

Physical properties and self-setting mechanism of calcium phosphate cements from calcium bis-dihydrogenophosphate monohydrate and calcium oxide.

An apatitic calcium phosphate cement was developed from calcium bis-dihydro-genophosphate monohydrate (or monocalcium phosphate monohydrate, MCPM) and calcium oxide (CaO). The powder had a Ca/P molar ratio of 1.67, and the liquid was either pure water or 0.25 M-1 M sodium phosphate buffer, pH 7.4. The influence of the powder-to-liquid (P/L) ratio on the setting time and the mechanical strength were studied. The best results were obtained for the 1 M phosphate buffer with a P/L ratio of 1.53; the setting time was 7 min and the compressive strength was 25 MPa after 24 h and 33 MPa after 11 d. The mechanism and kinetics of the setting reaction were investigated by X-ray diffraction, differential scanning calorimetry, 31P magic angle spinning-nuclear magnetic resonance and infrared spectrometry. The setting reaction was found to be biphasic: in the first step, during the mixing time, MCPM reacted with CaO immediately to give calcium hydrogenophosphate dihydrate (or dicalcium phosphate dihydrate, DCPD) which, in the second step, reacted more slowly with the remaining CaO to give hydroxyapatite. The conversion of the starting materials to hydroxyapatite was complete within 24 h when the liquid was water, but was slower and incomplete with the phosphate buffers. Of the starting materials, 30% remained after 3 d.

Chemical characterization of in vivo aged zinc polycarboxylate dental cements.

The chemical composition of zinc polycarboxylate dental cements aged in vivo was studied. Thirty samples aged from one to 17 years were investigated using X-ray diffraction, infrared spectroscopy, thermogravimetric analysis and differential scanning calorimetry. Evidence for the presence of zinc oxide, amorphous zinc polycarboxylate and water of hydration was found. No correlation with age concerning either the chemical structure of the components or their relative amounts was found. Zinc polycarboxylate dental cements show very good chemical stability on long-term use.

Chemical and structural changes in zinc polycarboxylate cements after immersion in dilute organic acid solutions.

The behaviour of zinc polycarboxylate cements in contact with dilute aqueous solutions of organic acids at concentrations close to those existing in buccal medium, was studied. The organic acids were acetic, citric, tartaric and lactic acids, at 0.01 M and 0.001 M. The elution of zinc and magnesium was 10-1000 times greater in acid than in pure water, and correlated with the concentrations and the dissociation constants, pK1, of the acids tested. In all cases, important water losses were observed. In the 0.01 M acids, the cement structure collapsed to form a viscous, compact and homogeneous layer on the cement surface. In this layer, the polymeric carboxylic chains were regenerated from the zinc and magnesium polycarboxylate cement. Comparison with pure water showed that even the smallest concentration of the weak acids greatly modified the cement behaviour. This could explain the well-known differences in erosion processes between theoretical erosion predicted by standard specification tests and the in vivo situation.

Infrared, raman, and 13C NMR spectra of two crystalline forms of (1R,3S)-3-(p-thioanisoyl)-1,2,2-trimethylcyclopentanecarboxylic acid.

A comparative structural analysis of the two polymorphic forms of (1R,3S)-3-(p-thioanisoyl)-1,2,2-trimethylcyclopentanecarboxylic acid has been performed with infrared, Raman, and 13C NMR spectroscopy. The results are compared with those of the crystallographic and thermal studies on the two forms published in previous papers. The enantiotropism of the polymorphs as well as the differences in the conformation of the carboxyl group and the resulting intermolecular hydrogen bonds were confirmed by the infrared and Raman studies.

Comparative study of the two polymorphic forms of p-(1R,3S) 3-thioanisoyl-1,2,2-trimethylcyclopentane carboxylic acid.

The crystal structure of polymorph I of p-(1R,3S)3-thioanisoyl-1,2,2-trimethylcyclopentane carboxylic acid has been determined and is compared with that of polymorph II that was previously described. Polymorph I is very different at the level of the carboxyl group. It does not present disorder and the values found for the C-O bonds correspond exactly to single and double bond lengths. In addition, the carboxyl groups of the two molecules in the cell packing are involved in symmetric hydrogen bonds [2.662(6) A] leading to the formation of a dimer around the twofold axis following x with a shift on z. The different conformations on the carboxylic group between the two polymorphs are in good agreement with the thermodynamic study.

[Study of preventive activity and health promotion in a primary care center]. / Estudio de la actividad de prevención y promoción de la salud en un centro de atención primaria.

The present study was undertaken in our center to investigate the application level of the criteria from the Program of Preventive Activities and Health Promotion (PAPPS) for the adult population of the SEMFYC, before the implementation of any specific activity. We carried out a simple random sampling (310 clinical records) and we registered their application for risk subpopulations. The most relevant results were as follows: screening for hypercholesterolemia 41.4%, for hypertension 27.2%, for smoking habits 45.8%, for chronic alcohol abuse 35.2%, and for obesity 13.6%. Those corresponding to women program and vaccinations were poor, except for influenza vaccination (39.7%). We evaluate the small preventive activity and its low effectiveness, which is related to the lack of protocols, of an adequate population ranging and of integrated approach. We conclude that there is a need for protocol approach and a population-oriented program of preventive activity, with an adequate recording system. We expect to achieve these goals by the adscription of the EAP to PAPPS.

[Quality control and optimization of therapeutic activity with the use of thermoanalytic methods]. / Contrôle de qualité et optimisation de l'activité thérapeutique à l'aide de méthodes thermoanalytiques.

Thermogravimetry, differential scanning calorimetry, thermomicroscopy, transparency measure permit drug quality control: knowledge of solvated or unsolvated mole, thermal stability, identification of crystalline form (polymorphism) quick determination of total impurity with graphs. These methods can be used for therapeutic activity optimization of very weakly soluble drugs: research of the polymorph showing the best kinetic dissolution, establishment of phase diagram drug/inert substance by example for determination invariant composition particularly eutectic for which the drug solubility is increased.

[Use of a volatile substrate to explore oxidative metabolism of xenobiotics in the rabbit lung]. / Utilisation d'un substrat volatil pour explorer le métabolisme oxydatif des xénobiotiques par le poumon chez le lapin.

A demethylation breath test was modeled in rabbits receiving 14C-anisole either by the intravenous route or by inhalation. The exhalation rate of 14CO2 was measured in a metabolic cage. The modeling hypothesis involved two metabolic compartments: a "central" compartment receiving the infusion, and a "pulmonary" compartment receiving the inhalation. The modeling succeeded in identifying a highly significant metabolic contribution of the lungs following inhalation of the substrate.