Effect of strontium and cooling rate upon eutectic temperatures of A319 aluminum alloy

DTA analysis was used to investigate the solidification reactions of alloy A319 with either 12 or 136 ppm of Sr added. Strontium does not affect primary solidification of (Al) dendrites but modifies the kinetics of the (Al)–Si eutectic. The effects of Sr level and of cooling rate on the characteristic temperatures for the (Al)–Si and other eutectic reactions are described

Hydrogen sulfide pathway and skeletal muscle: an introductory review.

The presence of the H2 S pathway in skeletal muscle (SKM) has recently been established. SKM expresses the three constitutive H2 S-generating enzymes in animals and humans, and it actively produces H2 S. The main, recognized molecular targets of H2 S, that is, potassium channels and PDEs, have been evaluated in SKM physiology in order to hypothesize a role for H2 S signalling. SKM dysfunctions, including muscular dystrophy and malignant hyperthermia, have also been evaluated as conditions in which the H2 S and transsulfuration pathways have been suggested to be involved. The intrinsic complexity of the molecular mechanisms involved in excitation-contraction (E-C) coupling together with the scarcity of preclinical models of SKM-related disorders have hampered any advances in the knowledge of SKM function. Here, we have addressed the role of the H2 S pathway in E-C coupling and the relative importance of cystathionine β-synthase, cistathionine γ-lyase and 3-mercaptopyruvate sulfurtransferase in SKM diseases

Baccharis funkiae (Compositae: Astereae), a New Narrow Endemic Species from Uruguay.

Baccharis funkiae, a new species endemic to Uruguay, is described and illustrated here. We also provide field work pictures, etymology, distribution and habitat, and preliminary conservation status information. Comments on how to differentiate it from the morphologically similar B. subopposita, highlighting differences setting the new species apart are discussed. Additionally, a key to the identification of the Uruguayan species belonging to Baccharis subgen. Baccharis sect. Cylindricae is presented

Baccharis rectialata (Compositae: Astereae): a new species of carqueja from Uruguay.

Se describe Baccharis rectialata (Compositae: Astereae), una nueva especie perteneciente a B. sect. Caulopterae, característica de los pastizales del noreste del Uruguay. La nueva especie es morfológicamente similar a B. crispa, de la que se diferencia en sus alas no sinuosas y sus involucros y papus más cortos en los capítulos estaminados. Este trabajo incluye la descripción morfológica detallada de la nueva especie, la distribución geográfica, datos del hábitat en que se desarrolla, la fenología y el estatus de conservación. Adicionalmente se examinan los principales caracteres que permiten diferenciar a B. rectialata de las especies morfológicamente más similares y se presenta una clave para la identificación de las especies de subarbustos que pertenecen a B. sect. Caulopterae presentes en Uruguay, junto con ilustraciones, imágenes, y el mapa de distribución de la nueva especie

Effect of Solidification Rate and Rare Earth Metal Addition on the Microstructural Characteristics and Porosity Formation in A356 Alloy

The present study was performed on A356 alloy with the main aim of investigating the effects of La and Ce additions to 356 alloys (with and without 100 ppm Sr) on the microstructure and porosity formation in these alloys. Measured amounts of La, Ce, and Sr were added to the molten alloy. The results showed that, in the absence of Sr, addition of La and Ce leads to an increase in the nucleation temperature of the α-Al dendritic network with a decrease in the temperature of the eutectic Si precipitation, resulting in increasing the freezing range. Addition of 100 ppm Sr results in neutralizing these effects. The presence of La or Ce in the casting has a minor effect on eutectic Si modification, in spite of the observed depression in the eutectic temperature. It should be noted that Ce is more effective than La as an alternate modifying agent. According to the atomic radius ratio, rLa/rSi is 1.604 and rCe/rSi is 1.559, theoretically, which shows that Ce is relatively more effective than La. The present findings confirm that Sr is the most dominating modification agent. Interaction between rare earth (RE) metals and Sr would reduce the effectiveness of Sr. Although modification with Sr causes the formation of shrinkage porosity, it also reacts with RE-rich intermetallics, resulting in their fragmentation

Revisiting the reaction of dicarbonyls in aerosol proxy solutions containing ammonia: the case of butenedial

Reactions in aqueous solutions containing dicarbonyls (especially the α-dicarbonyls methylglyoxal, glyoxal, and biacetyl) and reduced nitrogen (NHx) have been studied extensively. It has been proposed that accretion reactions from dicarbonyls and NHx could be a source of particulate matter and brown carbon in the atmosphere and therefore have direct implications for human health and climate. Other dicarbonyls, such as the 1,4-unsaturated dialdehyde butenedial, are also produced from the atmospheric oxidation of volatile organic compounds, especially aromatics and furans, but their aqueous-phase reactions with NHx have not been characterized. In this work, we determine a pH-dependent mechanism of butenedial reactions in aqueous solutions with NHx that is compared to α-dicarbonyls, in particular the dialdehyde glyoxal. Similar to glyoxal, butenedial is strongly hydrated in aqueous solutions. Butenedial reaction with NHx also produces nitrogen-containing rings and leads to accretion reactions that form brown carbon. Despite glyoxal and butenedial both being dialdehydes, butenedial is observed to have three significant differences in its chemical behavior: (1) as previously shown, butenedial does not substantially form acetal oligomers, (2) the butenedial/OH− reaction leads to light-absorbing compounds, and (3) the butenedial/NHx reaction is fast and first order in the dialdehyde. Building off of a complementary study on butenedial gas-particle partitioning, we suggest that the behavior of other reactive dialdehydes and dicarbonyls may not always be adequately predicted by α-dicarbonyls, even though their dominant functionalities are closely related. The carbon skeleton (e.g., its hydrophobicity, length, and bond structure) also governs the fate and climate-relevant properties of dicarbonyls in the atmosphere. If other dicarbonyls behave like butenedial, their reaction with NHx could constitute a regional source of brown carbon to the atmosphere.</p

A experiência vivida das mulheres numa zona rural de Asientos, Aguascalientes durante o período climatérico

Introduction: Nursing care seeks the integrity of the person in all spheres of development and thus improves quality of life. Objective: To know the experience of women who are in the climacteric stage and who live in a rural area of the municipality of Asientos, Aguascalientes. Methodology: Qualitative study with Heiddeger's hermeneutic phenomenological approach. Seven women participated. Seven phenomenological interviews were conducted for the collection of information to guarantee the quality of the study. Results: The interviews lasted approximately 40 minutes. Nine units of meaning were obtained, which were divided into two groups: ontic and ontological. The ontic meaning units included: ignorance of climacteric as a stage of life, distress in climacteric and medical care during climacteric. The other group includes the ontological meaning units: sexual desire in darkness, absence of a partner, the family world and the climacteric period, transcendence in the climacteric period, and suffering in the climacteric period. Conclusion: Climacteric women have an influence on the sociocultural environment, repetitive patterns and scarce knowledge of the subject.Introducción: El cuidado de enfermería busca la integridad de la persona en todas sus esferas de desarrollo y con ello mejora calidad de vida. Objetivo: Conocer la experiencia que tienen las mujeres que cursan la etapa del climaterio y que viven en zona rural del municipio de Asientos, Aguascalientes. Metodología: Estudio cualitativo con enfoque fenomenológico hermenéutico de Heiddeger. Participaron 7 mujeres. Para la recolección de la información se realizaron siete entrevistas fenomenológicas, para garantizar la calidad del estudio. Resultados: Las entrevistas tuvieron una duración aproximada de 40 minutos. Se obtuvo 9 unidades de significado, las cuales se dividieron en dos grupos: óntico y ontológico. En las unidades de significado óntico se incluyó: desconocimiento del climaterio como etapa de la vida, angustia en el climaterio y atención medica durante el climaterio. El otro grupo abarca las unidades de significado ontológico integrado por: el deseo sexual en tinieblas, ausencia de compañero, el mundo familiar y el climaterio, trascendencia en el climaterio, sufrimiento en el climaterio. Conclusión: Las mujeres climatéricas tienen una influencia sobre el entorno sociocultural, patrones repetitivos y conocimientos escasos del tema.Resumo: Introdução: Os cuidados de enfermagem procuram a integridade da pessoa em todas as esferas de desenvolvimento e assim melhorar a qualidade de vida. Objectivo: Descobrir a experiência das mulheres na fase climatérica da vida que vivem numa zona rural do município de Asientos, Aguascalientes. Metodologia: Estudo qualitativo com a abordagem fenomenológica hermenêutica de Heiddeger. Sete mulheres participaram. Foram realizadas sete entrevistas fenomenológicas para recolher a informação, a fim de garantir a qualidade do estudo. Resultados: As entrevistas duraram aproximadamente 40 minutos. Foram obtidas nove unidades de significado, que foram divididas em dois grupos: ontico e ontológico. As unidades de significado ôntico incluíam: ignorância do climatério como fase da vida, angústia no climatério e cuidados médicos durante o climatério. O outro grupo compreende as unidades de significado ontológico: desejo sexual na escuridão, ausência de parceiro, o mundo familiar e o climatério, transcendência no climatério, sofrimento no climatério. Conclusão: As mulheres climatéricas são influenciadas pelo ambiente sócio-cultural, padrões repetitivos e fraco conhecimento do assunto