246 research outputs found
Antiferromagnetic structure and electronic properties of BaCr2As2 and BaCrFeAs2
The chromium arsenides BaCr2As2 and BaCrFeAs2 with ThCr2Si2 type structure
(space group I4/mmm; also adopted by '122' iron arsenide superconductors) have
been suggested as mother compounds for possible new superconductors. DFT-based
calculations of the electronic structure evidence metallic antiferromagnetic
ground states for both compounds. By powder neutron diffraction we confirm for
BaCr2As2 a robust ordering in the antiferromagnetic G-type structure at T_N =
580 K with mu_Cr = 1.9 mu_B at T = 2K. Anomalies in the lattice parameters
point to magneto-structural coupling effects. In BaCrFeAs2 the Cr and Fe atoms
randomly occupy the transition-metal site and G-type order is found below 265 K
with mu_Cr/Fe = 1.1 mu_B. 57Fe Moessbauer spectroscopy demonstrates that only a
small ordered moment is associated with the Fe atoms, in agreement with
electronic structure calculations with mu_Fe ~ 0. The temperature dependence of
the hyperfine field does not follow that of the total moments. Both compounds
are metallic but show large enhancements of the linear specific heat
coefficient gamma with respect to the band structure values. The metallic state
and the electrical transport in BaCrFeAs2 is dominated by the atomic disorder
of Cr and Fe and partial magnetic disorder of Fe. Our results indicate that
Neel-type order is unfavorable for the Fe moments and thus it is destabilized
with increasing iron content.Comment: 14 pages, 14 figures, submitted to Physical Review
Simulating the potential of swarm grids for pre-electrified communities - A case study from Yemen
Swarm grids are an emerging approach for electrification in the Global South that interconnects individual household generation and storage to a small electricity network for making full use of existing generation capacities. Using a simulation tool for demand, weather, and power flows, we analyse the potential of an AC swarm grid for a large preelectrified village in rural Yemen. Service quality and financial indicators are compared to the cases of individual supply and a centralised micro grid.
While the swarm grid would, in fact, improve supply security from currently 12.4 % (Tier 2) to 81.7 % (Tier 3) at lower levelised costs, it would be inferior to the micro grid in both service (Tier 4) and costs. This is mainly driven by the large pre-installed fossil-fuel generator and storage capacities in our case study. However, this situation may
be representative for other relevant locations. Under these conditions, a swarm grid poses the danger to create (possibly-undesired) incentives to invest in diesel generators, and it may fail to support prosumerism effectively.
Nevertheless, the swarm’s evolutionary nature with the possibility for staggered investments (e.g. in smaller yet complementary groups of consumers) poses a central advantage over micro grids in the short-term alleviation of energy poverty
Simulating the potential of swarm grids for pre-electrified communities - A case study from Yemen
Swarm grids are an emerging approach for electrification in the Global South that interconnects individual household generation and storage to a small electricity network for making full use of existing generation capacities. Using a simulation tool for demand, weather, and power flows, we analyse the potential of an AC swarm grid for a large preelectrified village in rural Yemen. Service quality and financial indicators are compared to the cases of individual supply and a centralised micro grid.
While the swarm grid would, in fact, improve supply security from currently 12.4 % (Tier 2) to 81.7 % (Tier 3) at lower levelised costs, it would be inferior to the micro grid in both service (Tier 4) and costs. This is mainly driven by the large pre-installed fossil-fuel generator and storage capacities in our case study. However, this situation may
be representative for other relevant locations. Under these conditions, a swarm grid poses the danger to create (possibly-undesired) incentives to invest in diesel generators, and it may fail to support prosumerism effectively.
Nevertheless, the swarm’s evolutionary nature with the possibility for staggered investments (e.g. in smaller yet complementary groups of consumers) poses a central advantage over micro grids in the short-term alleviation of energy poverty
The Diterpenoid 7-Keto-Sempervirol, Derived from Lycium chinense, Displays Anthelmintic Activity against both Schistosoma mansoni and Fasciola hepatica
BACKGROUND:Two platyhelminths of biomedical and commercial significance are Schistosoma mansoni (blood fluke) and Fasciola hepatica (liver fluke). These related trematodes are responsible for the chronic neglected tropical diseases schistosomiasis and fascioliasis, respectively. As no vaccine is currently available for anti-flukicidal immunoprophylaxis, current treatment is mediated by mono-chemical chemotherapy in the form of mass drug administration (MDA) (praziquantel for schistosomiasis) or drenching (triclabendazole for fascioliasis) programmes. This overreliance on single chemotherapeutic classes has dramatically limited the number of novel chemical entities entering anthelmintic drug discovery pipelines, raising significant concerns for the future of sustainable blood and liver fluke control. METHODOLOGY/ PRINCIPLE FINDINGS:Here we demonstrate that 7-keto-sempervirol, a diterpenoid isolated from Lycium chinense, has dual anthelmintic activity against related S. mansoni and F. hepatica trematodes. Using a microtiter plate-based helminth fluorescent bioassay (HFB), this activity is specific (Therapeutic index = 4.2, when compared to HepG2 cell lines) and moderately potent (LD50 = 19.1 μM) against S. mansoni schistosomula cultured in vitro. This anti-schistosomula effect translates into activity against both adult male and female schistosomes cultured in vitro where 7-keto-sempervirol negatively affects motility/behaviour, surface architecture (inducing tegumental holes, tubercle swelling and spine loss/shortening), oviposition rates and egg morphology. As assessed by the HFB and microscopic phenotypic scoring matrices, 7-keto-sempervirol also effectively kills in vitro cultured F. hepatica newly excysted juveniles (NEJs, LD50 = 17.7 μM). Scanning electron microscopy (SEM) evaluation of adult F. hepatica liver flukes co-cultured in vitro with 7-keto-sempervirol additionally demonstrates phenotypic abnormalities including breaches in tegumental integrity and spine loss. CONCLUSIONS/ SIGNIFICANCE:7-keto-sempervirol negatively affects the viability and phenotype of two related pathogenic trematodes responsible for significant human and animal infectious diseases. This plant-derived, natural product is also active against both larval and adult developmental forms. As such, the data collectively indicate that 7-keto-sempervirol is an important starting point for anthelmintic drug development. Medicinal chemistry optimisation of more potent 7-keto-sempervirol analogues could lead to the identification of novel chemical entities useful for future combinatorial or replacement anthelmintic control
Implementation of electrochemical, optical and denuder-based sensors and sampling techniques on UAV for volcanic gas measurements : examples from Masaya, Turrialba and Stromboli volcanoes
Volcanoes are a natural source of several reactive
gases (e.g., sulfur and halogen containing species) and nonreactive
gases (e.g., carbon dioxide) to the atmosphere. The
relative abundance of carbon and sulfur in volcanic gas as
well as the total sulfur dioxide emission rate from a volcanic
vent are established parameters in current volcanomonitoring
strategies, and they oftentimes allow insights into
subsurface processes. However, chemical reactions involving
halogens are thought to have local to regional impact on
the atmospheric chemistry around passively degassing volcanoes.
In this study we demonstrate the successful deployment
of a multirotor UAV (quadcopter) system with custom-made
lightweight payloads for the compositional analysis and gas
flux estimation of volcanic plumes. The various applications
and their potential are presented and discussed in example
studies at three volcanoes encompassing flight heights of 450
to 3300m and various states of volcanic activity. Field applications
were performed at Stromboli volcano (Italy), Turrialba
volcano (Costa Rica) and Masaya volcano (Nicaragua).
Two in situ gas-measuring systems adapted for autonomous
airborne measurements, based on electrochemical and optical
detection principles, as well as an airborne sampling
unit, are introduced. We show volcanic gas composition results
including abundances of CO2, SO2 and halogen species.
The new instrumental setups were compared with established
instruments during ground-based measurements at Masaya
volcano, which resulted in CO2 = SO2 ratios of 3.6 0.4. For
total SO2 flux estimations a small differential optical absorption
spectroscopy (DOAS) system measured SO2 column
amounts on transversal flights below the plume at Turrialba
volcano, giving 1776 1108 T d1 and 1616 1007 T d1
of SO2 during two traverses. At Stromboli volcano, elevated
CO2 = SO2 ratios were observed at spatial and temporal proximity
to explosions by airborne in situ measurements. Reactive
bromine to sulfur ratios of 0.19 104 to 9.8 104
were measured in situ in the plume of Stromboli volcano,
down wind of the vent.Published2441-24574V. Processi pre-eruttiviJCR Journa
Excreted/secreted Schistosoma mansoni venom allergen-like 9 (SmVAL9) modulates host extracellular matrix remodelling gene expression
AbstractThe Schistosoma mansoni venom allergen-like (SmVAL) protein family consists of 29 members, each possessing a conserved α-β-α sandwich tertiary feature called the Sperm-coating protein/Tpx-1/Ag5/PR-1/Sc7 (SCP/TAPS) domain. While the SmVALs have been found in both excretory/secretory (E/S) products and in intra/sub-tegumental (non-E/S) fractions, the role(s) of this family in host/parasite relationships or schistosome developmental processes remains poorly resolved. In order to begin quantifying SmVAL functional diversity or redundancy, dissecting the specific activity (ies) of individual family members is necessary. Towards this end, we present the characterisation of SmVAL9; a protein previously found enriched in both miracidia/sporocyst larval transformation proteins and in egg secretions. While our study confirms that SmVAL9 is indeed found in soluble egg products and miracidia/sporocyst larval transformation proteins, we find it to be maximally transcribed/translated in miracidia and subsequently down-regulated during in vitro sporocyst development. SmVAL9 localisation within sporocysts appears concentrated in parenchymal cells/vesicles as well as associated with larval germinal cells. Furthermore, we demonstrate that egg-derived SmVAL9 carries an N-linked glycan containing a schistosome-specific difucosyl element and is an immunogenic target during chronic murine schistosomiasis. Finally, we demonstrate that recombinant SmVAL9 affects the expression of extracellular matrix, remodelling matrix metalloproteinase (MMP) and tissue inhibitors of metalloproteinase (TIMP) gene products in both Biomphalaria glabrata embryonic cell (BgMMP1) and Mus musculus bone marrow-derived macrophage (MmMMP2, MmMMP9, MmMMP12, MmMMP13, MmMMP14, MmMMP28, TIMP1 and TIMP2) in vitro cultures. These findings importantly suggest that excreted/secreted SmVAL9 participates in tissue reorganisation/extracellular matrix remodelling during intra-mammalian egg translocation, miracidia infection and intra-molluscan sporocyst development/migration
Lessons learned for social and behavior change programming from the USAID Zika response
Breakthrough RESEARCH documented the strengths, weaknesses, gaps, and challenges in social and behavior change (SBC) efforts to combat the Zika outbreak to inform future public health emergency programming. What were the successes, challenges, and gaps in designing, implementing, and adapting SBC programming in the USAID Zika response? What were the successes, challenges, and gaps in generating and using data and evidence in SBC programming in the USAID Zika response? What do the successes, challenges, and gaps of the USAID Zika response’s SBC programming imply for future health emergency responses? Eight recommendations are offered as a reslt of these research queries
Utilización de un recinto de la Universidad Nacional de Luján como modelo experimental y demostrativo para la aplicación de técnicas de acondicionamiento natural de bajo costo
Un pequeño recinto dentro de la Universidad Nacional de Luján es utilizado por el equipo de trabajo desde hace diez años como modelo experimental y demostrativo para la aplicación de técnicas de acondicionamiento ambiental de bajo costo y mÃnimo consumo energético. Con anterioridad al inicio de esta experiencia, el recinto era conocido por su pésima respuesta ambiental, sobre todo en el perÃodo cálido. Sobre el mismo fueron aplicadas con el tiempo sucesivas mejoras siguiendo una metodologÃa que apuntaba tanto a lo experimental como a lo pedagógico y demostrativo, dada la similitud constructiva que el recinto mostraba con las viviendas precarias que autoconstruyen sectores de menores recursos. En el trabajo se muestran las sucesivas técnicas utilizadas, los resultados parciales medidos como consecuencia de las mismas, hasta llegar al momento actual en que se demuestra la muy satisfactoria respuesta alcanzada en relación con el confort ambiental interior para cualquier época del año.For ten years, a research team has been using a small room at the National University of Lujan as an experimental demonstration model for the application of low-cost environmental conditioning energy-efficient techniques. Before starting this experience, the building was characterized for its poor environmental conditions, especially during the warm season. Over time, successive improvements were applied upon it following not only an experimental methodology but also educational and demonstrative ones, since this room had been made with similar building materials to the ones used in poor-quality housing of low-income self-builders. This paper shows the consecutive techniques applied and the measurement of the partial results obtained from the application of these techniques till the present time, which demonstrates a very satisfactory response related to the indoor environmental quality at any time of the year.Asociación Argentina de EnergÃas Renovables y Medio Ambiente (ASADES
Long-term air pollution and traffic noise exposures and mild cognitive impairment in older adults : a cross-sectional analysis of the Heinz Nixdorf recall study
Background: Mild cognitive impairment (MCI) describes the intermediate state between normal cognitive aging and dementia. Adverse effects of air pollution (AP) on cognitive functions have been proposed, but investigations of simultaneous exposure to noise are scarce.
Objectives: We analyzed the cross-sectional associations of long-term exposure to AP and traffic noise with overall MCI and amnestic (aMCI) and nonamnestic (naMCI) MCI.
Methods: At the second examination of the population-based Heinz Nixdorf Recall study, cognitive assessment was completed in 4,086 participants who were 50–80 years old. Of these, 592 participants were diagnosed as having MCI (aMCI, n = 309; naMCI, n = 283) according to previously published criteria using five neuropsychological subtests. We assessed long-term residential concentrations for size-fractioned particulate matter (PM) and nitrogen oxides with land use regression, and for traffic noise [weighted 24-hr (LDEN) and night-time (LNIGHT) means]. Logistic regression models adjusted for individual risk factors were calculated to estimate the association of environmental exposures with MCI in single- and two-exposure models.
Results: Most air pollutants and traffic noise were associated with overall MCI and aMCI. For example, an interquartile range increase in PM2.5 and a 10 A-weighted decibel [dB(A)] increase in LDEN were associated with overall MCI as follows [odds ratio (95% confidence interval)]: 1.16 (1.05, 1.27) and 1.40 (1.03, 1.91), respectively, and with aMCI as follows: 1.22 (1.08, 1.38) and 1.53 (1.05, 2.24), respectively. In two-exposure models, AP and noise associations were attenuated [e.g., for aMCI, PM2.5 1.13 (0.98, 1.30) and LDEN 1.46 (1.11, 1.92)].
Conclusions: Long-term exposures to air pollution and traffic noise were positively associated with MCI, mainly with the amnestic subtype
Schistosoma mansoni venom allergen-like proteins:Phylogenetic relationships, stage-specific transcription and tissue localization as predictors of immunological cross-reactivity
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Previous issue date: 2019Welcome Trust
(UK) (WT084273/Z/07/Z) to KFH, Fundação Butantan, Fundação
de Amparo à Pesquisa do Estado de São Paulo (Brazil) to LPF and
LLC (2012/23124-4), Conselho Nacional de Desenvolvimento
CientÃfico e Tecnológico (CNPq) to LCCL and Coordenação de Aperfeiçoamento
de Pessoal de NÃvel Superior – Brasil (CAPES) –
Finance Code 001, and by fellowships from Fundação de Amparo
à Pesquisa do Estado de São Paulo (FAPESP, Brazil) to LPF
(2008/57946-5) and HKF (2007/07685-8) and from CNPq to MIK
(160861/2017-9). We thank Dra. Eliana Nakano and Ms. Patricia
A. Miyasato for supplying the parasite stages and to Alexsander
Seixas de Souza for confocal microscopy (FAPESP 00/11624-5)
imaging support, all from Instituto Butantan, Brazil.Instituto Butantan. Centro de Biotecnologia. São Paulo, SP, Brasil / Fundação Oswaldo Cruz. Centro de Pesquisas Gonçalo Moniz. Salvador, BA, Brasil.Aberystwyth University. Institute of Biological. Environmental and Rural Sciences. Aberystwyth, UK.Aberystwyth University. Institute of Biological. Environmental and Rural Sciences. Aberystwyth, UK.Instituto Butantan. Centro de Biotecnologia. São Paulo, SP, Brasil.Aberystwyth University. Institute of Biological. Environmental and Rural Sciences. Aberystwyth, UK.Aberystwyth University. Institute of Biological. Environmental and Rural Sciences. Aberystwyth, UK.Fundação Oswaldo Cruz. Centro de Pesquisas Gonçalo Moniz. Salvador, BA, Brasil.Instituto Butantan. Centro de Biotecnologia. São Paulo, SP, Brasil / Universidade de São Paulo. Pós-Graduação Interunidades em Biotecnologia. São Paulo, SP, Brasil.Leiden University Medical Centre. Center for Proteomics and Metabolomics. RC Leiden, The Netherlands.Leiden University Medical Centre. Department of Parasitology. RC Leiden, The Netherlands.Instituto Butantan. Centro de Biotecnologia. São Paulo, SP, Brasil.Aberystwyth University. Institute of Biological. Environmental and Rural Sciences. Aberystwyth, UK.Schistosoma mansoni venom allergen-like proteins (SmVALs) are part of a diverse protein superfamily partitioned into two groups (group 1 and group 2). Phylogenetic analyses of group 1 SmVALs revealed that members could be segregated into subclades (A-D); these subclades share similar gene expression patterns across the parasite lifecycle and immunological cross-reactivity. Furthermore, whole-mount in situ hybridization demonstrated that the phylogenetically, transcriptionally and immunologically-related SmVAL4, 10, 18 and 19 (subclade C) were all localized to the pre-acetabular glands of immature cercariae. Our results suggest that SmVAL group 1 phylogenetic relationships, stage-specific transcriptional profiles and tissue localization are predictive of immunological cross-reactivity
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