Novel approach to plasma facing materials in nuclear fusion reactors

A novel material design in nuclear fusion reactors is proposed based on W-nDiamond nanostructured composites. Generally, a microstructure refined to the nanometer scale improves the mechanical strength due to modification of plasticity mechanisms. Moreover, highly specific grainboundary area raises the number of sites for annihilation of radiation induced defects. However, the low thermal stability of fine-grained and nanostructured materials demands the presence of particles at the grain boundaries that can delay coarsening by a pinning effect. As a result, the concept of a composite is promising in the field of nanostructured materials. The hardness of diamond renders nanodiamond dispersions excellent reinforcing and stabilization candidates and, in addition, diamond has extremely high thermal conductivity. Consequently, W-nDiamond nanocomposites are promising candidates for thermally stable first-wall materials. The proposed design involves the production of WAV-nDiamondAV-Cu/Cu layered castellations. The W, W-nDiamond and W-Cu layers are produced by mechanical alloying followed by a consolidation route that combines hot rolling with spark plasma sintering (SPS). Layer welding is achieved by spark plasma sintering. The present work describes the mechanical alloying processsing and consolidation route used to produce W-nDiamond composites, as well as microstructural features and mechanical properties of the material produced Long term plasma exposure experiments are planned at ISTTOK and at FTU (Frascati)

Virtual Environment, Digital Hypertext, Reading and Writing in Foreign Language

This work intends to analyze - in an activity carried out with students from the third period of the Language (Spanish) undergraduate course of a college located in Itaperuna, a town in the State of Rio de Janeiro, Brazil - how the digital hyper textual reading can facilitate the selection of information in order to facilitate the writing process of texts in Spanish that can be broadcasted in the virtual environment, verifying how this may happen, so that these productions are shared, also allowing the interaction of the subjects with the language and with their peers. For this objective, we used the qualitative methodology (Erickson, 1986) with action research, seeking foundation in what theorists such as Lévy (1996, 1999), Coscarelli (2006, 2009), Gomes et al. (2015), Bannell et al. (2016), among others, investigate. As results, we emphasize that the subjects of the research actively participated in the construction of their own learning regarding the aspects covered in the foreign language class, and with this they were able to practice reading, writing, and the USAge of the vocabulary and grammar studied. Finally, we conclude that the hypertext worked here as an inclusive device, facilitator of reading and propitiator of writing, making the participant students authors of digital texts that provided them with learning throughout all the process they have been through

Real-time intracellular temperature imaging using lanthanide-bearing polymeric micelles

Measurement of thermogenesis in individual cells is a remarkable challenge due to the complexity of the biochemical environment (such as pH and ionic strength) and to the rapid and yet not well-understood heat transfer mechanisms throughout the cell. Here, we present a unique system for intracellular temperature mapping in a fluorescence microscope (uncertainty of 0.2 K) using rationally designed luminescent Ln3+-bearing polymeric micellar probes (Ln = Sm, Eu) incubated in breast cancer MDA-MB468 cells. Two-dimensional (2D) thermal images recorded increasing the temperature of the cells culture medium between 296 and 304 K shows inhomogeneous intracellular temperature progressions up to ∼20 degrees and subcellular gradients of ∼5 degrees between the nucleolus and the rest of the cell, illustrating the thermogenic activity of the different organelles and highlighting the potential of this tool to study intracellular processes.publishe

Do Riparian Buffers Protect Stream Invertebrate Communities in South American Atlantic Forest Agricultural Areas?

We investigated the influence and relative importance of insecticides and other agricultural stressors in determining variability in invertebrate communities in small streams in intensive soy-production regions of Brazil and Paraguay. In Paraguay we sampled 17 sites on tributaries of the Pirapó River in the state of Itapúa and in Brazil we sampled 18 sites on tributaries of the San Francisco River in the state of Paraná. The riparian buffer zones generally contained native Atlantic forest remnants and/or introduced tree species at various stages of growth. In Brazil the stream buffer width was negatively correlated with sediment insecticide concentrations and buffer width was found to have moderate importance in mitigating effects on some sensitive taxa such as mayflies. However, in both regions insecticides had low relative importance in explaining variability in invertebrate communities, while various habitat parameters were more important. In Brazil, the percent coverage of soft depositional sediment in streams was the most important agriculture-related explanatory variable, and the overall stream-habitat score was the most important variable in Paraguay streams. Paraguay and Brazil both have laws requiring forested riparian buffers. The ample forested riparian buffer zones typical of streams in these regions are likely to have mitigated the effects of pesticides on stream invertebrate communities. This study provides evidence that riparian buffer regulations in the Atlantic Forest region are protecting stream ecosystems from pesticides and other agricultural stressors. Further studies are needed to determine the minimum buffer widths necessary to achieve optimal protection.Instituto de Limnología "Dr. Raúl A. Ringuelet

Exciton bimolecular annihilation dynamics in supramolecular nanostructures of conjugated oligomers

We present femtosecond transient absorption measurements on $\pi$-conjugated supramolecular assemblies in a high pump fluence regime. Oligo(\emph{p}-phenylenevinylene) monofunctionalized with ureido-\emph{s}-triazine (MOPV) self-assembles into chiral stacks in dodecane solution below 75$^{\circ}$C at a concentration of $4\times 10^{-4}$ M. We observe exciton bimolecular annihilation in MOPV stacks at high excitation fluence, indicated by the fluence-dependent decay of $1^1$B$_{u}$-exciton spectral signatures, and by the sub-linear fluence dependence of time- and wavelength-integrated photoluminescence (PL) intensity. These two characteristics are much less pronounced in MOPV solution where the phase equilibrium is shifted significantly away from supramolecular assembly, slightly below the transition temperature. A mesoscopic rate-equation model is applied to extract the bimolecular annihilation rate constant from the excitation fluence dependence of transient absorption and PL signals. The results demonstrate that the bimolecular annihilation rate is very high with a square-root dependence in time. The exciton annihilation results from a combination of fast exciton diffusion and resonance energy transfer. The supramolecular nanostructures studied here have electronic properties that are intermediate between molecular aggregates and polymeric semiconductors

Detecting new physics contributions to the D0-D0bar mixing through their effects on B decays

New physics effects may yield a detectable mass difference in the D0-D0bar system, Delta m_D. Here we show that this has an important impact on some B --> D decays. The effect involves a new source of CP violation, which arises from the interference between the phases in the B --> D decays and those in the D0-D0bar system. This interference is naturally large. New physics may well manifest itself through Delta m_D contributions to these B decays.Comment: 10 pages, Revtex, no figures. To appear in PR

Cognitive Decline Associated with Longitudinal Changes in 24-h Ambulatory Blood Pressure Variability

Background: Cognitive decline has been associated with variability in blood pressure (BP). However, whether the increment of the BP variability during follow-up precedes cognitive decline remains undocumented. We aimed this study to investigate cognitive decline in relation to longitudinal changes in 24-h reading-to-reading BP variability. Methods: We conducted an observational longitudinal study that included 717 dementia-free participants from the Maracaibo Aging Study who underwent follow-up assessment in both 24-h ambulatory BP monitoring and cognitive tests between 1998 and 2015. Cognitive domains consisted of selective reminding tests (total, long-term, short-term, and recognition memory) and the Mini-Mental State Examination (MMSE). Cognitive decline was a longitudinal decrease in cognitive scores. Participants underwent 24-h ambulatory BP monitoring between 2-4 times – with at least one-year interval. Systolic and diastolic BP variability was studied during 24-h and divided into daytime (from 06h00 to 23h00), and nighttime (23h00 to 06h00) periods. To account for BP level, we used variability independent of the mean (VIM) to compute systolic and diastolic BP variability. Other measures of BP variability included the nocturnal BP drop in comparison to the daytime BP level, which was estimated as the night-to-day ratio. Statistics included multivariate linear regression mixed models. Results: Overall, the mean age was 65.6±7.36 years old and 66.5% (n=447) of the participants were women. In mixed models, a decline in all memory domains was associated with greater variability in the 24-h, daytime, and nighttime systolic BP during follow-up, with an estimated decline in cognitive scores ranging from -0.2 to -0.04 points per unit increase in VIM systolic BP during follow-up (P values ranged from 0.022 to 0.003). Decline in total, short-term, and MMSE memory domains was associated with greater 24-h and daytime diastolic BP variability (P≤0.015). A lower night-to-day dipping ratio during follow-up increased the risk of cognitive decline, with a -5.8 to -1.6 decline in long-term memory and MMSE scores; respectively (P≤0.037). Conclusions: Cognitive decline associates with greater reading-to-reading 24-h BP variability and lower falls in nocturnal BP over time. These findings might be indicative of deteriorated regulatory mechanisms to maintain steady BP levels as individuals age

Normal-tension glaucomatous optic neuropathy is related to blood pressure variability in the Maracaibo Aging Study

Hypoperfusion of the optic nerve might be involved in the pathogenesis of normal-tension glaucomatous optic neuropathy (GON). Mean arterial pressure (MAP) drives ocular perfusion, but no previous studies have addressed the risk of GON in relation to blood pressure (BP) variability, independent of BP level. In a cross-sectional study, 93 residents of Maracaibo, Venezuela, underwent optical coherence tomography, visual field assessments and 24-h ambulatory BP monitoring between 2011 and 2016. We investigated the association of normal-tension GON with or without visual field defects with reading-to reading variability of 24-h MAP, as captured by variability independent of the MAP level (VIMmap). Odds ratios (ORs) were adjusted for 24-h MAP level and for a propensity score of up to five risk factors. Among the 93 participants (87.1% women; mean age, 61.9 years), 26 had open-angle normal-tension GON at both eyes; 14 had visual field defects; and 19 did not have visual field defects. The OR ratios for normal-tension GON, expressed per 1-SD increment in VIMmap (2 mm Hg), were 2.17 (95% confidence interval, 1.33–3.53) unadjusted; 2.20 (1.35–3.61) adjusted for 24-h MAP level only; 1.93 (1.10–3.41) with additional adjustment for age, educational attainment, high-density lipoprotein (HDL) cholesterol and office hypertension; and 1.95 (1.10–3.45) in models including intraocular pressure. We confirmed our a priori hypothesis that BP variability, most likely operating via hypoperfusion of the optic nerve, is associated with normal-tension GON. 24-H ambulatory BP monitoring might therefore help stratify the risk of normal-tension GON