Vacancy-assisted domain-growth in asymmetric binary alloys: A Monte Carlo Study

A Monte Carlo simulation study of the vacancy-assisted domain growth in asymmetric binary alloys is presented. The system is modeled using a three-state ABV Hamiltonian which includes an asymmetry term. Our simulated system is a stoichiometric two-dimensional binary alloy with a single vacancy which evolves according to the vacancy-atom exchange mechanism. We obtain that, compared to the symmetric case, the ordering process slows down dramatically. Concerning the asymptotic behavior it is algebraic and characterized by the Allen-Cahn growth exponent x51/2. The late stages of the evolution are preceded by a transient regime strongly affected by both the temperature and the degree of asymmetry of the alloy. The results are discussed and compared to those obtained for the symmetric case

Wheat lines, suffering structural rearrangements between wheat-1BS and rye-1RS chromosomes, display differential patterns of magnesium accumulation

Poster no. 238Two near isogenic lines, designated as 1RS and 1RW, resulting from the recombination of the rye (Secale cereale) chromosome 1RS with chromosome 1BS of bread wheat (Triticum aestivum), differ in a relatively small region of that short chromosome arm. We have recently reported that chromosome rearrangements in this region imply modifications in the dosage of some genes (including OPRIII codifying an enzyme involved in jasmonic acid (JA) biosynthesis pathway). This dosage difference confer differential drought resistance in a way primarily associated to the capacity of roots for soil exploration. An emerging question is whether or not those rearrangements also differentially influence plant mineral nutrition. In the present study we analyzed the ionome of 1RS and 1RW, which unveiled the existence of relevant differences in the distribution of magnesium (Mg) between the shoot and the root of these lines. Following this observation, we explored the physiological and molecular determinants of differential magnesium accumulation observed.Instituto de Recursos BiológicosFil: Gualano, L.D. Consejo Nacional de Investigaciones Científicas y Técnicas. Instituto Tecnológico Chascomús; Argentina. Universidad Nacional de San Martín; ArgentinaFil: Moriconi, Jorge. Consejo Nacional de Investigaciones Científicas y Técnicas. Instituto Tecnológico Chascomús; Argentina. Universidad Nacional de San Martín; ArgentinaFil: Tranquilli, Gabriela. Instituto Nacional de Tecnología Agropecuaria (INTA). Instituto de Recursos Biológicos; ArgentinaFil: Santa-María, Guillermo E. Consejo Nacional de Investigaciones Científicas y Técnicas. Instituto Tecnológico Chascomús; Argentina. Universidad Nacional de San Martín; Argentin

Heat Sensing Receptor TRPV1 Is a Mediator of Thermotaxis in Human Spermatozoa

The molecular bases of sperm thermotaxis, the temperature-oriented cell motility, are currently under investigation. Thermal perception relies on a subclass of the transient receptor potential [TRP] channels, whose member TRPV1 is acknowledged as the heat sensing receptor. Here we investigated the involvement of TRPV1 in human sperm thermotaxis. We obtained semen samples from 16 normozoospermic subjects attending an infertility survey programme, testis biopsies from 6 patients with testicular germ cell cancer and testis fine needle aspirates from 6 patients with obstructive azoospermia undergoing assisted reproductive technologies. Expression of TRPV1 mRNA was assessed by RT-PCR. Protein expression of TRPV1 was determined by western blot, flow cytometry and immunofluorescence. Sperm motility was assessed by Sperm Class Analyser. Acrosome reaction, apoptosis and intracellular-Ca2+ content were assessed by flow cytometry. We found that TRPV1 mRNA and protein were highly expressed in the testis, in both Sertoli cells and germ-line cells. Moreover, compared to no-gradient controls at 31°C or 37°C (Ctrl 31°C and Ctrl 37°C respectively), sperm migration towards a temperature gradient of 31-37°C (T gradient) in non-capacitated conditions selected a higher number of cells (14,9 ± 4,2×106 cells T gradient vs 5,1± 0,3×106 cells Ctrl 31°C and 5,71±0,74×106 cells Ctrl 37°C; P = 0,039). Capacitation amplified the migrating capability towards the T gradient. Sperms migrated towards the T gradient showed enriched levels of both TRPV1 protein and mRNA. In addition, sperm cells were able to migrate toward a gradient of capsaicin, a specific agonist of TRPV1, whilst capsazepine, a specific agonist of TRPV1, blocked this effect. Finally, capsazepine severely blunted migration towards T gradient without abolishing. These results suggest that TRPV1 may represent a facilitating mediator of sperm thermotaxis

Elastocaloric effect in vulcanized natural rubber and natural/wastes rubber blends

Vulcanized natural/wastes rubber blends were prepared and their elastocaloric properties were analysed. A thermodynamic frame was used to discriminate the contributions of thermoelastic effects and strain induced crystallization/melting. The substitution of 20 wt% of the natural rubber matrix by waste rubber particles resulted in a maintain and even a slight improvement of heat exchanges (+10%), that we ascribed to a (i) high thermoelastic effect and a (ii) a high ability of the natural rubber matrix to crystallize due to a nucleation ability of the waste particles, both resulting from a strain amplification in the rubber phase due to undeformable carbon black aggregates in the waste particles. The materials coefficient of performance, COPmat, was estimated equal to 4.4 for the neat natural rubber and 3.8 for the blend containing 20 wt% of wastes due to larger mechanical energy originated from reinforcing effect of waste particles. Nonetheless, the elastocaloric (eC) abilities of these materials, especially their wide temperature spans (similar to those in films or polycrystals using rare earth elements) make these natural/waste rubber blends good candidates for application such as heating/cooling machines. Moreover, the partial replacement of natural rubber, a bio-source material showing risks of shortage, by industrial wastes rubber, place these blends as promising eco-friendly materials with high added value

Contributo para a recuperação e integração museológica do Laboratório e Amphitheatro de Chimica da Escola Politécnica de Lisboa

0 Museu de Ciência da Universidade de Lisboa (MCUL) foi criado oficialmente em 1985 pelo Decreto-lei n 146/85, de 8 de Maio, tendo o edifíco da antiga Escola Politécnica sido atribuídos às suas instalações, conjuntamente com o Museu Nacional de História Natural. Já desde 1978 fora proposta por Fernando Bragança Gil a reconstrução do edifíco destruído pelo incêndio do mesmo ano, para instalação do Museu de Ciência, nas áreas onde funcionavam os grupos de Matemática, Física e Química, a par da reinstalação do Museu Nacional de História Natural na ala oriental do mesmo edifcio. Far-se-ia assim "a cobertura, de um ponto de vista museológico, das ciências ditas fundamentais, cujo ensino e investigação se processou na Faculdade de Ciências" (Bragança Gil, 1994: 28). Era, assim, naturalmente incluído no MCUL o Laboratório Chimico e Amphitheatro, que dele faziam parte integrante (fig. 1). Contudo, a morosidade da construção das novas instalações para a Faculdade de Ciências da Universidade de Lisboa, fez com que o Museu só dispusesse de facto do Laboratório em Outubro de 1999

A wheat/rye polymorphism affects seminal root length and yield across different irrigation regimes

The introgression of a small segment of wheat (Triticumaestivum L.) chromosome arm 1BS in the distal region of rye (Secalecereale L.) 1RS.1BL arm translocation in wheat (henceforth 1RSRW) was previously associated with reduced grain yield, carbon isotope discrimination and stomatal conductance, suggesting reduced access to soil moisture. Here we show that lines with the normal 1RS arm have longer roots than lines with the 1RSRW arm in both field and hydroponic experiments. In the 1RSRW lines, differences in seminal root length were associated with a developmentally regulated arrest of the root apical meristem (RAM). Approximately 10 days after germination, the seminal roots of the 1RSRW plants showed a gradual reduction in elongation rate, and stopped growing a week later. Seventeen days after germination, the roots of the 1RSRW plants showed altered gradients of reactive oxygen species and emergence of lateral roots close to the RAM, suggesting changes in the root meristem. The 1RSRW lines also showed reduced biomass (estimated by Normalized Differences Vegetation Index) and grain yield relative to the 1RS lines, with larger differences under reduced or excessive irrigation than under normal irrigation. These results suggest that this genetic variation could be useful to modulate root architecture.Fil: Howell, Tyson. University of California; Estados UnidosFil: Moriconi, Jorge Ignacio. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Instituto de Investigaciones Biotecnológicas. Instituto de Investigaciones Biotecnológicas "Dr. Raúl Alfonsín" (sede Chascomús). Universidad Nacional de San Martín. Instituto de Investigaciones Biotecnológicas. Instituto de Investigaciones Biotecnológicas "Dr. Raúl Alfonsín" (sede Chascomús); ArgentinaFil: Zhao, Xueqiang. Chinese Academy of Sciences; República de ChinaFil: Joshua Hegarty. University of California; Estados UnidosFil: Fahima, Tzion. University of Haifa; IsraelFil: Santa Maria, Guillermo Esteban. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Instituto de Investigaciones Biotecnológicas. Instituto de Investigaciones Biotecnológicas "Dr. Raúl Alfonsín" (sede Chascomús). Universidad Nacional de San Martín. Instituto de Investigaciones Biotecnológicas. Instituto de Investigaciones Biotecnológicas "Dr. Raúl Alfonsín" (sede Chascomús); Argentin

Modelización de un sistema territorial “urbano-rural” para la evaluación de su sostenibilidad. Aplicación a una zona representativa del País Vasco

El desarrollo de una base de conocimiento común y sólida que permita la máxima objetividad y transparencia en la evaluación de la sostenibilidad dentro del proceso de toma de decisiones, constituye uno de los pilares básicos para su implementación en el planeamiento estratégico y la gestión del territorio. La caracterización del sistema ecológico-ambiental, económico, social e institucional que es objeto de gestión constituye un paso clave en el conocimiento de la red de relaciones que subyace al funcionamiento del sistema y de las interacciones responsables de potenciales sinergias. La traducción de esta información en modelos conceptuales y matemáticos constituye una herramienta útil en el desarrollo de indicadores de sostenibilidad eficaces y relevantes, enfocados desde las necesidades de gestión. En este trabajo se presenta el modelo conceptual que define los componentes e interacciones de un sistema urbano-rural representativo del País Vasco, así como su marco de evaluación.One of the most important factors in introducing the concept of sustainability into strategic planning and territorial management is the development of a shared, solid knowledge base. This knowledge base should ensure maximum objectivity and transparency in sustainability assessment within the decision-making process. A description of the ecological-environmental, economic, social and institutional system that is to be managed is needed in order to develop knowledge about the network of relations that underlie the functioning of the system and the interactions that are responsible for potential synergies. The transformation of this information into conceptual and mathematical models is a useful tool for developing effective and relevant sustainability indicators that are oriented towards management needs. This paper presents a conceptual model that defines the components and interactions of a representative urban-rural system in the Basque Country. It also discusses the assessment frame for this model

Linking Oxidative Events to Inflammatory and Adaptive Gene Expression Induced by Exposure to an Organic Particulate Matter Component

Background: Toxicological studies have correlated inflammatory effects of diesel exhaust particles (DEP) with its organic constituents, such as the organic electrophile 1,2-naphthoquinone (1,2-NQ)

PAC1 receptor-mediated clearance of tau in postsynaptic compartments attenuates tau pathology in mouse brain

Accumulation of pathological tau in synapses has been identified as an early event in Alzheimer's disease (AD) and correlates with cognitive decline in patients with AD. Tau is a cytosolic axonal protein, but under disease conditions, tau accumulates in postsynaptic compartments and presynaptic terminals, due to missorting within neurons, transsynaptic transfer between neurons, or a failure of clearance pathways. Using subcellular fractionation of brain tissue from rTg4510 tau transgenic mice with tauopathy and human postmortem brain tissue from patients with AD, we found accumulation of seed-competent tau predominantly in postsynaptic compartments. Tau-mediated toxicity in postsynaptic compartments was exacerbated by impaired proteasome activity detected by measuring lysine-48 polyubiquitination of proteins targeted for proteasomal degradation. To combat the accumulation of tau and proteasome impairment in the postsynaptic compartments of rTg4510 mouse brain, we stimulated the pituitary adenylate cyclase-activating polypeptide (PACAP) type 1 receptor (PAC1R) with its ligand PACAP administered intracerebroventricularly to rTg4510 mice. We observed enhanced synaptic proteasome activity and reduced total tau in postsynaptic compartments in mouse brain after PACAP treatment. The clearance of tau from postsynaptic compartments correlated with attenuated tauopathy and improved cognitive performance of rTg4510 transgenic mice on two behavioral tests. These results suggest that activating PAC1R could prevent accumulation of aggregate-prone tau and indicate a potential therapeutic approach for AD and other tauopathies