Molecular structure of uranium carbides: isomers of UC3.

In this article, the most relevant isomers of uranium tricarbide are studied through quantum chemical methods. It is found that the most stable isomer has a fan geometry in which the uranium atom is bonded to a quasilinear C3 unit. Both, a rhombic and a ring CU(C2) structures are found about 104-125 kJ/mol higher in energy. Other possible isomers including linear geometries are located even higher. For each structure, we provide predictions for those molecular properties (vibrational frequencies, IR intensities, dipole moments) that could eventually help in their experimental detection. We also discuss the possible routes for the formation of the different UC3 isomers as well as the bonding situation by means of a topological analysis of the electron density.

Quartz crystal Microbalance with dissipation monitoring for biomedical applications: Open source and low cost prototype with active temperature control.

Advances in sensors have revolutionized the biomedical engineering field, having an extreme affinity for specific analytes also providing an effective, real-time, point-of-care testing for an accurate diagnosis. Quartz Crystal Microbalance (QCM) is a well-established sensor that has been successfully applied in a broad range of applications to monitor and explore various surface interactions, in situ thin-film formations, and layer properties. This technology has gained interest in biomedical applications since novel QCM systems are able to work in liquid media. QCM with dissipation monitoring (QCM-D) is an expanded version of a QCM that measures changes in damping properties of adsorbed layers thus providing information on its viscoelastic nature. In this article, an open source and low cost QCM-D prototype for biomedical applications was developed. In addition, the system was validated using different Polyethylene Glycol (PEG) concentrations due to its importance for many medical applications. The statistics show a bigger dissipation of the system as the fluid becomes more viscous, also having a very acceptable sensibility when temperature is controlled.

On the molecular structure of uranium dicarbide: T-shape versus linear isomers.

A theoretical study of the molecular structure of uranium dicarbide has been carried out employing DFT, coupled cluster, and multiconfigurational methods. A triangular species, corresponding to a (5)A(2) electronic state, has been found to be the most stable UC(2) species. A triplet linear CUC species, which has been observed in recent infrared spectroscopy experiments, lies much higher in energy. A topological analysis of the electronic density has also been carried out. The triangular species is shown to be in fact a T-shape structure with a U-C interaction which can be considered to be a closed-shell interaction.

Adsorption of alkenes on acidic zeolites. Theoretical study based on the electron charge density.

In the present work, experiments on electron density changes in the adsorption process of alkenes on acidic zeolites, in the framework of atoms in molecules theory (AIM), were carried out. Electron densities were obtained at MP2 and B3LYP levels using a 6-31++G(d,p) basis set. This study explores the energetic and the electron density redistributions associated with O-H...pi interactions. The main purpose of this work is to provide an answer to the following questions: (a) Which and how large are the changes induced on the molecular electron distribution by the formation of adsorbed alkenes? (b) Can a reasonable estimate of the adsorption energy of alkenes on the active site of zeolite be solely calculated from an analysis of the electron densities? We have used topological parameters to determine the strength and nature of the interactions in the active site of the zeolite. All the results derived from the electron density analysis show that the stabilization of the adsorbed alkenes follows the order isobutene > trans-2-butene congruent with 1-butene congruent with propene > ethene, reflecting the order of basicity of C=C bonds, i.e., (C(ter)=C(prim)) > (C(sec)=C(sec)) congruent with (C(prim)=C(sec)) > (C(prim)=C(prim)). In addition, we have found a useful set of topological parameters that are good for estimating the adsorption energy in adsorbed alkenes.

Theoretical analysis of the electronic properties of the sex pheromone and its analogue derivatives in the female processionary moth Thaumetopoea pytiocampa.

In the present work, the distribution of the electronic charge density of the natural sex pheromone, the (Z)-13-hexadecen-11-ynyl acetate, in the female processionary moth, Thaumetopoea pytiocampa, and its nine analogue derivatives was studied within the framework of the Density Functional Theory and the Atoms in Molecules (AIM) Theory at B3LYP/6-31G *//B3LYP/6-31++G * * level. Additionally, molecular electrostatic potential (MEP) maps of the previously mentioned compounds were computed and compared. Furthermore, the substitution of hydrogen atoms from the methyl group in the acetate group by electron withdrawing substituents (i.e., halogen atoms) as well as the replacement effect of hydrogen by electron donor substituents (+I effect) as methyl group, were explored. The key feature of the topological distribution of the charge density in analogue compounds, such as the variations of the topological properties encountered in the region formed by neighbouring atoms from the substitution site were presented and discussed. Using topological parameters, such as electronic charge density, Laplacian, kinetic energy density, and potential energy density evaluated at bond critical points (BCP), we provide here a detailed analysis of the nature of the chemical bonding of these molecules. In addition, the atomic properties (population, charge, energy, volume, and dipole moment) were determined on selected atoms. These properties were analyzed at the substitution site (with respect to the natural sex pheromone) and related to the biological activity and to the possible binding site with the pheromone binding protein, (PBP). Moreover, the Laplacian function of the electronic density was used to locate electrophilic regions susceptible to be attacked (by deficient electron atoms or donor hydrogen). Our results indicate that the change in the atomic properties, such as electronic population and atomic volume, are sensitive indicators of the loss of the biological activity in the analogues studied here. The crucial interaction between the acetate group of the natural sex pheromone and the PBP is most likely to be a hydrogen bonding and the substitution of hydrogen atoms by electronegative atoms in the pheromone molecule reduces the hydrogen acceptor capacity. This situation is mirrored by the diminish of the electronic population on carbon and oxygen atoms at the carbonylic group in the halo-acetate group. Additionally, the modified acetate group (with electronegative atoms) shows new charge concentration critical points or regions of concentration of charge density in which an electrophilic attack can also occur. Finally, the use of the topological analysis based in the charge density distribution and its Laplacian function, in conjunction with MEP maps provides valuable information about the steric volume and electronic requirement of the sex pheromone for binding to the PBP.

Serie de casos clínicos de pacientes con Miopatía inflamatoria idiopática y Enfermedad pulmonar intersticial del registro de Miopatías inflamatorias idiopáticas de la Sociedad Argentina de Reumatología / Series of clinical cases of patients with idiopathic inflammatory myopathy and interstitial lung disease from the registry of idiopathic inflammatory myopathies of the Argentine Society of Rheumatology

Las Miopatías Inflamatorias Idiopáticas (MII) son un grupo heterogéneo de enfermedades que se caracterizan por debilidad muscular e inflamación subyacente en la biopsia muscular. Los principales órganos afectados son el músculo, la piel y también puede afectarse el pulmón. Se distinguen dentro de los subtipos clínicos como Polimiositis (PM), Dermatomiositis (DM), DM con la variante Dermatomiositis Clínicamente Amiopática (DMCA), el Síndrome Antisintetasa (SAS), la Miositis Necrotizante Inmunomediada, la Miositis por Cuerpos de Inclusión (MCI) y la Miositis Asociada a Neoplasia. La presencia de ciertos anticuerpos específicos y asociados predispone al desarrollo de manifestaciones clínicas, determinando el pronóstico de la enfermedad. Se presentan 4 pacientes del Registro de MII de la Sociedad Argentina de Reumatología (SAR) con estas características: un paciente con PM y anti Jo-1 positivo y tres pacientes con DM (uno con DMCA y anti- RO 52 y dos pacientes con anti-PL7 y anti-TIF1γ respectivamente).

Idiopathic Inflammatory Myopathies (MII) are a heterogeneous group of diseases characterized by muscle weakness and inflammation underlying muscle biopsy. The main organs affected are muscle, skin and the lung can also be affected. They are distinguished within clinical subtypes such as Polymyositis (PM), Dermatomyositis (DM), DM with the variant Clinically Amiopathic Dermatomyositis (DMCA), the Syndrome Antisynthetase (SAS), Immune-mediated Necrotizing Myositis, Body Myositis Inclusion (MCI) and Neoplasia-Associated Myositis. The presence of certain specific and associated antibodies predisposes to the development of clinical manifestations, determining the disease prognosis. 4 patients from the Registry of MII of the Argentine Society of Rheumatology (SAR) are presented with these characteristics: one patient with PM and anti Jo-1 positive and three patients with DM (one with DMCA and anti-RO 52 and two patients with anti-PL7 and anti-TIF1γ respectively).

Serie de casos clínicos de pacientes con Miopatía inflamatoria idiopática y Enfermedad pulmonar intersticial del registro de Miopatías inflamatorias idiopáticas de la Sociedad Argentina de Reumatología / Clinical case series of patients with idiopathic inflammatory myopathy and interstitial lung disease from the SAR's Registry of Idiopathic Inflammatory Myopathies

Las Miopatías Inflamatorias Idiopáticas (MII) son un grupo heterogéneo de enfermedades que se caracterizan por debilidad muscular e inflamación subyacente en la biopsia muscular. Los principales órganos afectados son el músculo, la piel y también puede afectarse el pulmón. Se distinguen dentro de los subtipos clínicos como Polimiositis (PM), Dermatomiositis (DM), DM con la variante Dermatomiositis Clínicamente Amiopática (DMCA), el Síndrome Antisintetasa (SAS), la Miositis Necrotizante Inmunomediada, la Miositis por Cuerpos de Inclusión (MCI) y la Miositis Asociada a Neoplasia. La presencia de ciertos anticuerpos específicos y asociados predispone al desarrollo de manifestaciones clínicas, determinando el pronóstico de la enfermedad. Se presentan 4 pacientes del Registro de MII de la Sociedad Argentina de Reumatología (SAR) con estas características: un paciente con PM y anti Jo-1 positivo y tres pacientes con DM (uno con DMCA y anti-RO 52 y dos pacientes con anti-PL7 y anti-TIF1γ respectivamente).

Idiopathic Inflammatory Myopathies (MII) are a heterogeneous group of diseases characterized by muscle weakness and inflammation underlying muscle biopsy. The main organs affected are muscle, skin and the lung can also be affected. They are distinguished within clinical subtypes such as Polymyositis (PM), Dermatomyositis (DM), DM with the variant Clinically Amiopathic Dermatomyositis (DMCA), the Syndrome Antisynthetase (SAS), Immune-mediated Necrotizing Myositis, Body Myositis Inclusion (MCI) and Neoplasia-Associated Myositis. The presence of certain specific and associated antibodies predisposes to the development of clinical manifestations, determining the disease prognosis. 4 patients from the Registry of MII of the Argentine Society of Rheumatology (SAR) are presented with these characteristics: one patient with PM and anti Jo-1 positive and three patients with DM (one with DMCA and anti-RO 52 and two patients with anti-PL7 and anti-TIF1γ respectively).

Actividad física y factores de riesgo cardiovascular: evidencia de su interrelación a nivel nacional / Physical activity and cardiovascular risk factors: evidence of their interrelation nationwide

RESUMEN Antecedentes: En nuestro país la prevalencia de diabetes tipo 2 (DT2) y de factores de riesgo cardiovascular (FRCV) aumenta continuamente. Aunque el fenómeno se acompaña de adopción de estilos de vida no saludable que facilitan dicho crecimiento, es escasa la implementación de estrategias que puedan modificar la situación. Objetivo: Revisar la evidencia disponible sobre la magnitud del problema de la diabetes y los FRCV en nuestro país, su posible relación con la práctica de actividad física y potencial mecanismo de acción. Metodología: Evaluación de datos de la tercera Encuesta Nacional de Factores de Riesgo (ENFR) e información referida a factores que contribuyen al crecimiento de la prevalencia de DT2. Igualmente estrategias exitosas utilizadas a nivel mundial para su prevención. Resultados: El índice de masa corporal registrado en la población estudiada muestra un aumento del porcentaje de personas con sobrepeso/obesidad inverso a la práctica de actividad física. Igualmente los resultados de las pruebas de tolerancia a la glucosa oral muestran que sus alteraciones (prediabetes/diabetes) son menores entre quienes realizaban actividad física. El porcentaje de personas con valores de presión arterial dentro del rango normal al igual que de colesterol circulante (según valores meta de guías internacionales), es también significativamente menor entre quienes practicaban actividad física. Conclusión: La evidencia presentada demuestra objetivamente la necesidad/ventajas de implementar un programa de prevención primaria de diabetes a gran escala a nivel nacional para disminuir su crecimiento y la pertinencia de incluir la práctica de actividad física como estrategia de prevención tal como propone el PPDBA.

ABSTRACT Background: In our country, the prevalence of type 2 diabetes (DT2) and cardiovascular risk factors (CVRF) increases continuously. Although the phenomenon is accompanied by the adoption of unhealthy lifestyles that facilitate such growth, there is little implementation of strategies that can modify the situation. Objective: To review the available evidence on the magnitude of the problem of diabetes and CVRF in our country, its possible relationship with the practice of physical activity and potential mechanism of action. Methodology: Evaluation of data from the Third National Survey of Risk Factors (ENFR) and information referred to factors that promote the prevalence growth of T2D. Additionally, successful strategies have been used worldwide for its prevention. Results: The body mass index registered in the studied population shows an increase in the percentage of people with overweight/obesity inverse to the practice of physical activity. Likewise, the results of the oral glucose tolerance tests show that their alterations (prediabetes/ diabetes) are lower among those who performed physical activity. The percentage of people with blood pressure values within the normal range as well as circulating cholesterol (according to target values of international guidelines), is also significantly lower among those who practiced physical activity. Conclusion: The presented evidence objectively demonstrates the need/advantages of implementing a large-scale diabetes primary prevention program at the national level to.

Topological analysis of the electronic charge density in the ethene protonation reaction catalyzed by acidic zeolite.

In the present work, the distribution of the electronic charge density in the ethene protonation reaction by a zeolite acid site is studied within the framework of the density functional theory and the atoms in molecules (AIM) theory. The key electronic effects such as topological distribution of the charge density involved in the reaction are presented and discussed. The results are obtained at B3LYP/6-31G(**) level theory. Attention is focused on topological parameters such as electron density, its Laplacian, kinetic energy density, potential energy density, and electronic energy density at the bond critical points (BCP) in all bonds involved in the interaction zone, in the reactants, pi-complex, transition state, and alkoxy product. In addition, the topological atomic properties are determined on the selected atoms in the course of the reaction (average electron population, N(Omega), atomic net charge, q(Omega), atomic energy, E(Omega), atomic volume, v(Omega), and first moment of the atomic charge distribution, M(Omega)) and their changes are analyzed exhaustively. The topological study clearly shows that the ethene interaction with the acid site of the zeolite cluster, T5-OH, in the ethene adsorbed, is dominated by a strong O-H...pi interaction with some degree of covalence. AIM analysis based on DFT calculation for the transition state (TS) shows that the hydrogen atom from the acid site in the zeolitic fragment is connected to the carbon atom by a covalent bond with some contribution of electrostatic interaction and to the oxygen atom by closed shell interaction with some contribution of covalent character. The C-O bond formed in the alkoxy product can be defined as a weaker shared interaction. Our results show that in the transition state, the dominant interactions are partially electrostatic and partially covalent in nature, in which the covalent contribution increases as the concentration and accumulation of the charge density along the bond path between the nuclei linked increases.

Patterns of drug, alcohol and tobacco use among high school students in Santiago, Chile.

A survey using a self-administered questionnaire, based on a sample of 1,240 students from four public schools in Santiago, showed that 70.1 per cent of the students used alcohol, 56.3 per cent tobacco, 7.3 per cent cannabis, 2.5 per cent tranquillizers, 1.9 per cent stimulants and 0.7 per cent tranquillizers together with stimulants. Frequent alcohol consumption was found among 14.5 per cent of the students, 11.1 per cent of them smoked more than six cigarettes a day and 1.4 per cent smoked cannabis more than once a week. Consumption of these substances were more frequent among students who came from presumably more affluent residential neighbourhoods. Easy access to drugs played an important role in the occurrence of drug abuse.

Long-term follow-up of contralateral lobe in patients hemithyroidectomized for solitary follicular adenoma.

OBJECTIVES: Since there are no available conclusive studies on the long-term evolution of remnant thyroid tissue after hemithyroidectomy in patients who undergo surgery for solitary follicular adenomas, we searched for such cases in our records to elucidate this issue. DESIGN: Search criteria were as follows: (i) presence of a single palpable thyroid nodule with the remainder of the gland normal on palpation; (ii) clinically euthyroid status at the time of surgery; (iii) histological diagnosis of nodule as follicular adenoma; (iv) a hemithyroidectomy operation, sparing the contralateral lobe; (v) normal macroscopic aspect of the contralateral lobe at the time of surgery; and (vi) at least 4 years of postoperative follow-up. PATIENTS: Only 47 female cases were found to meet above criteria, with a mean age of 45.9 years (range: 23-79) at the time of surgery and a mean follow-up of 7.2 years (range: 4-32). Besides evaluating the presence or absence of antithyroid antibodies and the extranodular histology of tissue removed during surgery, a preoperative TRH test also allowed patients to be classified into two groups: normal extranodular thyroid (NET) (n = 32) and abnormal extranodular thyroid (AET) (n = 15). RESULTS: Eleven of the 15 patients with AET had thyroid autoimmunity, with or without overt histological thyroiditis, and the remaining four had subclinical hypothyroidism with negative antithyroid antibody titres. In the entire study population, only 28 patients received treatment with L-T4 immediately after surgery, none of whom had any alterations in the contralateral lobe. However, six of the nineteen patients not treated with T4 (31.6%) developed overt abnormalities in the contralateral lobe, including the only three with AET who had not received L-T4 treatment. The remaining three were two patients with NET, who showed postoperative TSH hyper-responsiveness to TRH (peak TSH > 25 mU/l), and one who developed a new follicular adenoma 32 years later. To date, none of the patients with NET, who had a normal TRH test after surgery, have developed any kind of alterations in the contralateral lobe, even those who received no L-T4 prophylactic treatment. CONCLUSIONS: The findings of this study suggest that: (i) there is a higher risk of follicular adenomas developing in a gland affected by thyroid autoimmunity than in a previously normal gland; (ii) L-T4 therapy may prevent the formation of new nodules or the development of goitre in the contralateral lobe; and (iii) in the absence of prophylactic treatment after surgery, the contralateral lobe of subjects with thyroid autoimmunity and/or previous subclinical hypothyroidism develops morphological abnormalities.

Evaluacion de la madurez pulmonar fetal por medio del examen ultrasonico de la placenta. / Evaluation of the pulmonary fetal maturing by ultrasonic test of the placenta

Partiendo de un conocimiento ya consolidado, el de los grados de maduracion de las placenta examinada con ultrasonidos, los autores relacionan los mismos, con parametros de liquido amniotico (L.A.) en especial fosfatidiglicerol (F.G.). En su serie todas las placentas grado 3, se asociaron a la presencia del F.G. en el liquido amniotico. Considerando que la sola presencia de este fosfolipido en el L.A. indica madurez del surfactante pulmonar, permite afirmar que en las gestaciones cuyas placentas ofrecem madurez ecografica grado 3, el feto tendra tambien maduro el surfactante pulmonar y en consecuencia no es necesario, en esas circunstancias efectuar amniocentesis para estudiar el L.A