Thermal Stability of Cu-Al-Ni Shape Memory Alloy Thin Films Obtained by Nanometer Multilayer Deposition.

Cu-Al-Ni is a high-temperature shape memory alloy (HTSMA) with exceptional thermomechanical properties, making it an ideal active material for engineering new technologies able to operate at temperatures up to 200 °C. Recent studies revealed that these alloys exhibit a robust superelastic behavior at the nanometer scale, making them excellent candidates for developing a new generation of micro-/nano-electromechanical systems (MEMS/NEMS). The very large-scale integration (VLSI) technologies used in microelectronics are based on thin films. In the present work, 1 µm thickness thin films of 84.1Cu-12.4 Al-3.5Ni (wt.%) were obtained by solid-state diffusion from a multilayer system deposited on SiNx (200 nm)/Si substrates by e-beam evaporation. With the aim of evaluating the thermal stability of such HTSMA thin films, heating experiments were performed in situ inside the transmission electron microscope to identify the temperature at which the material was decomposed by precipitation. Their microstructure, compositional analysis, and phase identification were characterized by scanning and transmission electron microscopy equipped with energy dispersive X-ray spectrometers. The nucleation and growth of two stable phases, Cu-Al-rich alpha phase and Ni-Al-rich intermetallic, were identified during in situ heating TEM experiments between 280 and 450 °C. These findings show that the used production method produces an HTSMA with high thermal stability and paves the road for developing high-temperature MEMS/NEMS using shape memory and superelastic technologies.

Size effect and scaling power-law for superelasticity in shape-memory alloys at the nanoscale.

Shape-memory alloys capable of a superelastic stress-induced phase transformation and a high displacement actuation have promise for applications in micro-electromechanical systems for wearable healthcare and flexible electronic technologies. However, some of the fundamental aspects of their nanoscale behaviour remain unclear, including the question of whether the critical stress for the stress-induced martensitic transformation exhibits a size effect similar to that observed in confined plasticity. Here we provide evidence of a strong size effect on the critical stress that induces such a transformation with a threefold increase in the trigger stress in pillars milled on [001] L21 single crystals from a Cu-Al-Ni shape-memory alloy from 2 µm to 260 nm in diameter. A power-law size dependence of n = -2 is observed for the nanoscale superelasticity. Our observation is supported by the atomic lattice shearing and an elastic model for homogeneous martensite nucleation.

Relationship of dropout and psychopathology in a high school sample in Mexico.

School dropout has significant consequences for both individuals and societies. Only 21% of adults in Mexico achieve the equivalent of a high school education. We examined the relationship between school dropout and self-reported psychiatric symptoms in a middle school in a suburb of Mexico City. We used binomial logistic regression to examine the odds ratio (OR) of school dropout associated with students' self-reported psychopathology. Two-hundred thirty-seven students participated in the study. Psychosis [OR = 8.0 (95% confidence interval, CI: 1.7-37.2)], depression [OR = 4.7 (95% CI: 2.2-9.7)], tic disorders [OR = 3.7 (95% CI: 1.4-9.5)], ADHD [OR = 3.2 (95% CI: 1.5-6.4)], and social phobia [OR = 2.6 (95% CI: 1.2-5.8)] were associated with increased risk of school dropout after controlling for age and gender as covariates. Our study suggested that students' self-reported psychopathology is associated with increased school dropout in Mexico. ADHD and depression may be particularly useful childhood psychiatric disorders to target with public health interventions because they explain the greatest amount of the variance in school dropout of child psychiatric disorders.

Effect of magnesium oxide (MgO) addition in diets for lactating holstein cows / Efecto de la adición de óxido de magnesio (MgO) en dietas para vacas holstein en lactación

It was evaluated the effect of magnesium oxide (MgO) addition in diets for Holstein cows on milk production and quality. Nineteen Holstein cows in second third of lactation were assigned to two treatments (T), with 9 and 10 animals. Both treatments were similar for days in lactation and milk yield. Cows were assigned at random to two treatments (T) groups: T1 received 0.2% and T2 received 0.4% of MgO. The MgO (alkalinizing agent) was mixed with a commercial concentrate and offered in feed bunk with total diet, which consisted of 9 kg/d of concentrate plus alfalfa hay fed ad libitum. Total diet was offered three times a day (0600; 1200 and 1700 h). The experimental period was of 30 d, with other 30 for adaptation. Milk production (kg/d) and milk quality (fat, protein, and total solids) were evaluated. Data were analyzed using the statistical package SAS through of a randomized block design. Animals on T2 (0.40% MgO) produced 2.85 kg/d more milk (P<0.50) than those on T1 (0.20% MgO). The fat, protein and total solids content in milk were higher (P<0.05) in T1 than in T2. It is concluded that the addition of 0.4% MgO in diets for lactating dairy cows resulted in milk production increased, although there was a small reduction in milk quality, compared with 0.2% MgO supplementation.

Se evaluó el efecto de adición de óxido de magnesio (MgO) en dietas para vacas Holstein sobre la producción y calidad de la leche. Diecinueve vacas Holstein en el segundo tercio de lactancia fueron asignadas a dos tratamientos (T), con 9 y 10 animales. Ambos tratamientos fueron similares para días de lactancia y producción de leche. Las vacas fueron asignadas al azar a dos grupos o tratamientos (T): T1 recibió 0,2%, y T2 recibió 0,4% de MgO. El MgO (agente alcalinizante) se mezcló con un concentrado comercial y se ofreció en el comedero junto con la dieta total, la cual consistió de 9 kg/d del concentrado mas heno de alfalfa ad libitum. La dieta total se ofreció 3 veces al día (06000, 1200 and 1700 h). El periodo experimental fue de 30 d, con otros 30 d de adaptación. Se evaluó la producción de leche (kg/d) y la calidad de la leche (grasa, proteína, y sólidos totales). Los datos se analizaron por medio del paquete estadístico SAS en un diseño de bloques al azar. Los animales en T2 (0,4% MgO) produjeron más leche (2,5 kg/d; P<0,05) que aquellos en T1 (0,20% MgO). El contenido de grasa, proteína, y sólidos totales en leche fue más alto (P<0,05) en T1 que en T2. Se concluye que la adición de 0,40% de MgO en dietas para vacas lactantes incrementa la producción de leche, sin embargo puede haber una pequeña reducción en la calidad de la leche, comparado con la suplementación de 0,20% de MgO.

Treatment preference and attitude toward pharmacotherapy and psychotherapy in Latin America. ULAD Task Force

Abstract: The development of psychopharmacolgy has reached a considerable progress in the treatment of mental illnesses, although patients have an ambivalent opinion regarding its use. It is generally believed that psychoactive drugs produce secondary effects, such as the potential capacity to create addiction. Little is known about the health professionals' attitude towards the risks or benefits of psychopharmacology in the treatment of mental illnesses. Objective To determine the preferences towards the type of treatment (psychopharmacology vs. psychotherapy) and the attitudes in regard to the specific use of psychodrugs that prevail among health professionals in 13 countries of Latin America. Method A total of l868 surveys was applied to psychiatrists, non-psychiatric doctors, and psychologists in l3 countries of Latin America. The survey covered the following items: a) questionnaire on the preferences regarding the treatment of mental illnesses, including personality disorders; b) attitude scale on the use of psychodrugs, and c) patient's attitude perceived by doctors while prescribing psychotherapeutical drugs. Results Pharmacotherapy was preferred by non-psychiatric doctors; psychologists had a negative attitude towards its use pointing out its secondary effects and the risk of addiction; psychiatrists and non-psychiatric doctors held a more favorable opinion. Doctors' opinion as to the patients' attitude towards psychotherapeutical drugs indicates that the latter accept taking them when they are properly informed regarding its use. Conclusión There is no doubt that psychiatrists and non-psychiatric doctors have a better knowledge about the benefits offered by psychoactive drugs and their potential secondary effects. Psychologists postulate psychotherapy as basic treatment because their knowledge about the benefits of pharmacological treatment is limited. Nonpsychiatric doctors have a medical education that permits them to know more deeply the therapeutical action of psychotherapeutical drugs despite knowing less about the psychotherapeutical process.

Resumen: Aunque el desarrollo de la psicofarmacología ha presentado considerables avances en el tratamiento de las enfermedades mentales, los pacientes tienen una opinión ambivalente acerca de su uso. En general, se piensa que los fármacos psicoactivos presentan efectos secundarios como su potencial capacidad para generar adicción. Se conoce poco acerca de la actitud que tienen los profesionales de la salud sobre el riesgo-beneficio del uso de la psicofarmacología en el tratamiento de las enfermedades mentales. Objetivo Determinar las preferencias hacia el tratamiento (psicofarmacología vs. psicoterapia) y la actitud hacia el uso específico de los psicofármacos en profesionistas de la salud de 13 países latinoamericanos. Método Se aplicaron 1868 encuestas a psiquiatras, médicos no psiquiatras y psicólogos de 13 países latinoamericanos. La encuesta desarrollada contó con los siguientes apartados: a) Cuestionario sobre las preferencias de tratamiento en 11 enfermedades mentales, incluidos trastornos de la personalidad; b) escala de actitud sobre el uso de psicofármacos, c) actitud del paciente percibida por los médicos cuando prescriben psicofármacos. Resultados En la preferencia por el tratamiento, entre los médicos no psiquiatras predominó la farmacoterapia. Los psicólogos manifiestan una actitud negativa, indicando sus efectos secundarios y el riesgo de adicción. Los médicos psiquiatras y no psiquiatras opinaron más favorablemente. La actitud del paciente hacia los psicofármacos, en opinión de los médicos, indica que aceptan su uso cuando son informados adecuadamente. Conclusiones Es indudable que los médicos psiquiatras y no psiquiatras tienen un mayor conocimiento sobre los beneficios que proporcionaron los fármacos psicoactivos; también poseen un mejor conocimiento de los efectos secundarios potenciales. Los psicólogos postulan como tratamiento primordial la psicoterapia por su limitado conocimiento de los beneficios del tratamiento psicofármacológico. Los psiquiatras tienen una formación médica que les permite conocer con mayor profundidad las acciones terapéuticas de los psicofármacos y tienen menos conocimiento del proceso psicoterapéutico.

Cell lines derived from hippocampal neurons of the normal and trisomy 16 mouse fetus (a model for Down syndrome) exhibit neuronal markers, cholinergic function, and functional neurotransmitter receptors.

We have established hippocampal cell lines from normal and trisomy 16 fetal mice, a model of human trisomy 21. Both cell lines, named H1b (derived from a normal animal) and HTk (trisomic) possess neuronal markers by immunohistochemistry (enolase, synaptophysin, microtubule associated protein-2, and choline acetyltransferase) and lack glial markers (glial fibrillary acidic protein and S-100). Also, we evaluated intracellular Ca(2+) levels ([Ca(2+)](i)) in response to neurotransmitter agonists, in cells loaded with the fluorescent Ca(2+) indicators Indo-1 and Fluo-3. Both cell lines responded to glutamatergic stimuli induced by glutamate, N-methyl-D-aspartate, I-amino-2,3-dihydro-5-methyl-3-oxo-4-isoxazole propanoic acid or kainate. Glutamate responses were only partially prevented by addition of 5 mM EGTA and the metabotropic glutamate receptor agonist, trans-(1S,3R)-1-amino-1,3-cyclopentanedicarboxylic acid (ACPD), increased [Ca(2+)](i) in both cell types. These results confirm the presence of glutamatergic metabotropic receptors. In glutamate-induced responses, HTk cells exhibited slower time-dependent decay kinetics than H1b cells. Cholinergic agonists (nicotine and muscarine) induced a rapid, transient increase in [Ca(2+)](i) in both cell types. Furthermore, some cells were sensitive to histamine and norepinephrine. All responses to the aforementioned agonists were prevented by addition of specific antagonists. We also studied incorporation and release of [(3)H]choline in the cells, and observed no differences in uptake parameters. However, release induced by K(+) and nicotine depolarization was greatly reduced in HTk cells. The results show that H1b and HTk cells retain neuronal characteristics and respond to specific neurotransmitter stimuli. The HTk differences could be related to neuronal pathophysiology in Down syndrome.

Análisis neuropsicológico de las características cognoscitivas de un grupo de adolescentes con trastorno por déficit de atención / Neuropsychological analysis of the cognitive characteristics of a group of teenagers with attention deficit disorder

De acuerdo con la literatura, es poco lo que se sabe sobre las características neuropsicológicas de los pacientes con trastorno por déficit de atención (TDA). La tendencia actual de la investigación se ha centrado en el estudio del funcionamiento ejecutivo, sin tomar en cuenta otros aspectos de la cognición. En este estudio se evaluaron, en un sentido más amplio, las habilidades cognoscitivas de un grupo de 30 pacientes adolescentes con TDA (media de edad = 17.1; DE = 2.1) por medio de la Escala de Inteligencia para Adultos de Wechsler (WAIS) y de la Figura Compleja de Rey. Se buscó analizar comparativamente las distintas funciones implicadas en la solución de problemas y generar un modelo que explicara las interrelaciones de las características cognoscitivas del grupo. Los pacientes obtuvieron un C.I. total promedio dentro del rango normal(media = 102.3, DE = 7.5), sin discrepancias significativas entre los valores de C.I. verbal y de ejecución. El análisis factorial de las 11 subescalas del WAIS generó 4 factores que explican el 74.1 por ciento de la varianza total, dos de los cuales correlacionaron significativamente con el valor del C.I. total. También se efectuó una análisis de trayectorias por medio de regresión lineal múltiple para establecer el modelo hipotético que se deseaba comprobar y un análisis estructural con el programa AMOS. El modelo obtenido presentó un buen porcentaje de ajuste con los datos empíricos (78.9 por ciento; con un error de 0.067). En la Figura Compleja de Rey, tanto el puntaje del ensayo de copia, como el del ensayo de memoria, se ubicó significativamente por debajo de los parámetros establecidos para la media de la población. Se concluye que el valor del C.I. del WAIS no discrimina al grupo de pacientes, pero sí las interrelaciones que guardan entre sí las distintas subescalas. También se encontraron defectos significativos en la habilidad gráfica que, al igual que los trastornos en el funcionamiento ejecutivo, pueden ser característicos de este tipo de pacientes, apoyando, a la vez, la hipótesis del compromiso en el funcionamiento del hemisferio cerebral derecho en el TDA.