560 research outputs found
Environmental tipping points for sperm motility, fertilization, and embryonic development in the crown-of-thorns starfish
For broadcast spawning invertebrates such as the crown-of-thorns starfish, early life history stages (from spawning to settlement) may be exposed to a wide range of environmental conditions, and could have a major bearing on reproductive success and population replenishment. Arrested development in response to multiple environmental stressors at the earliest stages can be used to define lower and upper limits for normal development. Here, we compared sperm swimming speeds and proportion of motile sperm and rates of fertilization and early development under a range of environmental variables (temperature: 20–36 oC, salinity: 20–34 psu, and pH: 7.4–8.2) to identify environmental tipping points and thresholds for reproductive success. We also tested the effects of water-soluble compounds, derived from eggs, on sperm activity. Our results demonstrate that gametes, fertilization, and embryonic development are robust to a wide range of temperature, salinity, and pH levels that are outside the range found at the geographical limits of adult distribution and can tolerate environmental conditions that exceed expected anomalies as a result of climate change. Water-soluble compounds derived from eggs also enhanced sperm activity, particularly in environmental conditions where sperm motility was initially limited. These findings suggest that fertilization and embryonic development of crown-of-thorns starfish are tolerant to a wide range of environmental conditions, though environmental constraints on recruitment success may occur at later ontogenic stages
Food by-product valorization by using plant-based coagulants combined with AOPs for agro-industrial wastewater treatment
Re-using and adding value to by-products is one of the current focuses of the agri-food industry, following the Sustainable Development Goals of United Nations. In this work, the by-products of four plants, namely chestnut burr, acorn peel, olive leaf, and grape stem were used as coagulants to treat elderberry wastewater (EW), a problematic liquid effluent. EW pre-treatment using these natural coagulants showed promising results after pH and coagulant dosage optimization. However, the decrease in total organic carbon (TOC) was not significant, due to the addition of the plant-based natural coagulants which contain carbon content. After this pre-treatment, the photo-Fenton advanced oxidation process was selected, after preliminary assays, to improve the global performance of the EW treatment. Photo-Fenton was also optimized for the parameters of pH, H2O2, Fe2+, and irradiance power, and the best conditions were applied to the EW treatment. Under the best operational conditions defined in the parametric study, the combined results of coagulation–flocculation–decantation (CFD) and photo-Fenton for chestnut burr, acorn peel, olive leaf, and grape stem were, respectively, 90.2, 89.5, 91.5, and 88.7% for TOC removal; 88.7, 82.0, 90.2 and 93.1%, respectively, for turbidity removal; and finally, 40.6, 42.2, 45.3, and 39.1%, respectively, for TSS removal. As a final remark, it is possible to suggest that plant-based coagulants, combined with photo-Fenton, can be a promising strategy for EW treatment that simultaneously enables valorization by adding value back to food by-products.Fundação para a Ciência e a Tecnologia | Ref. PD/BD/135332/2017Fundação para a Ciência e a Tecnologia | Ref. UIDB/04033/2020Fundação para a Ciência e a Tecnologia | Ref. UIDB/00616/2020Fundação para a Ciência e a Tecnologia | Ref. UIDB/04129/202
Thermodynamic properties of binary HCP solution phases from special quasirandom structures
Three different special quasirandom structures (SQS) of the substitutional
hcp binary random solutions (, 0.5, and 0.75) are
presented. These structures are able to mimic the most important pair and
multi-site correlation functions corresponding to perfectly random hcp
solutions at those compositions. Due to the relatively small size of the
generated structures, they can be used to calculate the properties of random
hcp alloys via first-principles methods. The structures are relaxed in order to
find their lowest energy configurations at each composition. In some cases, it
was found that full relaxation resulted in complete loss of their parental
symmetry as hcp so geometry optimizations in which no local relaxations are
allowed were also performed. In general, the first-principles results for the
seven binary systems (Cd-Mg, Mg-Zr, Al-Mg, Mo-Ru, Hf-Ti, Hf-Zr, and Ti-Zr) show
good agreement with both formation enthalpy and lattice parameters measurements
from experiments. It is concluded that the SQS's presented in this work can be
widely used to study the behavior of random hcp solutions.Comment: 15 pages, 8 figure
Exantema após vacinação do sarampo: análise laboratorial de casos notificados em São Paulo
OBJECTIVE: The clinical differential diagnosis of rash due to viral infections is often difficult, and misdiagnosis is not rare, especially after the introduction of measles and rubella vaccination. A study to determine the etiological diagnosis of exanthema was carried out in a group of children after measles vaccination. METHODS: Sera collected from children with rash who received measles vaccine were reported in 1999. They were analyzed for IgM antibodies against measles virus, rubella virus, human parvovirus B19 (HPV B19) using ELISA commercial techniques, and human herpes virus 6 (HHV 6) using immunofluorescence commercial technique. Viremia for each of those viruses was tested using a polimerase chain reaction (PCR). RESULTS: A total of 17 cases of children with exanthema after measles immunization were reported in 1999. The children, aged 9 to 12 months (median 10 months), had a blood sample taken for laboratory analysis. The time between vaccination and the first rash signs varied from 1 to 60 days. The serological results of those 17 children suspected of measles or rubella infection showed the following etiological diagnosis: 17.6% (3 in 17) HPV B19 infection; 76.5% (13 in 17) HHV 6 infection; 5.9% (1 in 17) rash due to measles vaccine. CONCLUSIONS: The study data indicate that infection due to HPV B19 or HHV 6 can be misdiagnosed as exanthema due to measles vaccination. Therefore, it is important to better characterize the etiology of rash in order to avoid attributing it incorrectly to measles vaccine.OBJETIVO: O diagnóstico diferencial de doenças exantemáticas causadas por vírus é geralmente difícil, e equívocos não são raros, especialmente depois da introdução da vacina contra o sarampo e a rubéola. Um estudo laboratorial foi conduzido com o objetivo de estabelecer o diagnóstico etiológico de casos de exantema em crianças que receberam a vacina contra o sarampo. MÉTODOS: Soros de casos de exantema em crianças que receberam vacina contra o sarampo, em 1999, foram analisados para anticorpos IgM contra os vírus do sarampo, da rubéola e do parvovírus humano B19 (HPV B19), por técnicas comerciais de Elisa, e o herpes vírus humano tipo 6 (HHV 6), por técnica comercial de imunofluorecência. A viremia para cada um desses vírus foi testada pela reação em cadeia da polimerase (PCR). RESULTADOS: Foram notificados, em 1999, 17 casos de crianças com exantema pós-vacinal. A idade das crianças era de nove a 12 meses (mediana, dez meses). Uma amostra de sangue colhida para investigação laboratorial foi obtida para cada criança. O tempo decorrido entre a aplicação da vacina e o aparecimento do exantema variou de um a 60 dias. Os resultados da sorologia das 17 crianças sugeriram o seguinte diagnóstico etiológico para o exantema: 17,6% (três em 17) infecção pelo HPV B19; 76,5% (13 em 17) infecção pelo HHV 6; 5,9% (um em 17) exantema originado pela vacina do sarampo. CONCLUSÃO: Os resultados indicaram que a infecção pelo HPV B19 ou pelo HHV 6 pode ser diagnosticada como sarampo de origem vacinal. Portanto, é fundamental incluir esses vírus no diagnóstico laboratorial para corretamente apontar a etiologia das doenças exantemáticas, evitando, assim, atribuir à vacina do sarampo efeito colateral
HST/FOS Eclipse Observations of the Nova-like Cataclysmic Variable UX Ursae Majoris
[abridged abstract]
We present and analyze Hubble Space Telescope observations of the eclipsing
nova-like cataclysmic variable UX UMa obtained with the Faint Object
Spectrograph. Two eclipses each were observed with the G160L grating (covering
the ultraviolet waveband) in August of 1994 and with the PRISM (covering the
near-ultraviolet to near-infrared) in November of the same year. The system was
50% brighter in November than in August, which, if due to a change in the
accretion rate, indicates a fairly substantial increase in Mdot_acc by >~ 50%.
Model disk spectra constructed as ensembles of stellar atmospheres provide
poor descriptions of the observed post-eclipse spectra, despite the fact that
UX UMa's light should be dominated by the disk at this time. Suitably scaled
single temperature model stellar atmospheres with T_eff = 12,500-14,500 K
actually provide a better match to both the ultraviolet and optical
post-eclipse spectra. Evidently, great care must be taken in attempts to derive
accretion rates from comparisons of disk models to observations.
One way to reconcile disk models with the observed post-eclipse spectra is to
postulate the presence of a significant amount of optically thin material in
the system. Such an optically thin component might be associated with the
transition region (``chromosphere'') between the disk photosphere and the fast
wind from the system, whose presence has been suggested by Knigge & Drew
(1997).Comment: 35 pages, including 12 figures; to appear in the ApJ (Vol. 499
Ultrahigh Surface Area Three-Dimensional Porous Graphitic Carbon from Conjugated Polymeric Molecular Framework
Porous graphitic carbon is essential for many applications such as energy storage devices, catalysts, and sorbents. However, current graphitic carbons are limited by low conductivity, low surface area, and ineffective pore structure. Here we report a scalable synthesis of porous graphitic carbons using a conjugated polymeric molecular framework as precursor. The multivalent cross-linker and rigid conjugated framework help to maintain micro- and mesoporous structures, while promoting graphitization during carbonization and chemical activation. The above unique design results in a class of highly graphitic carbons at temperature as low as 800 ??C with record-high surface area (4073 m2 g-1), large pore volume (2.26 cm-3), and hierarchical pore architecture. Such carbons simultaneously exhibit electrical conductivity >3 times more than activated carbons, very high electrochemical activity at high mass loading, and high stability, as demonstrated by supercapacitors and lithium-sulfur batteries with excellent performance. Moreover, the synthesis can be readily tuned to make a broad range of graphitic carbons with desired structures and compositions for many applications.clos
Recovery of 29-s Oscillations in HST/FOS Eclipse Observations of the Cataclysmic Variable UX Ursae Majoris
[abridged abstract]
Low amplitude (~=0.5%) 29-s oscillations have been detected in HST/FOS
eclipse observations of the nova-like cataclysmic variable UX UMa. These are
the same dwarf nova-type oscillations that were originally discovered in this
system by Warner & Nather in 1972. The oscillations are sinusoidal to within
the small observational errors and undergo an approximately -360 degree phase
shift during eclipses. Their amplitudes are highest at pre-eclipse orbital
phases and exhibit a rather gradual eclipse whose shape is roughly similar to
UX~UMa's overall light curve. Oscillation spectra derived from pre-eclipse data
segments are extremely blue, whereas mid-eclipse oscillation spectra are much
redder.
We suggest that the ultimate source of the oscillations is a hot, compact
region near disk center, but that a significant fraction of the observed,
modulated flux is due to reprocessing of the light emitted by this source in
the accretion disk atmosphere. The compact source is occulted at orbital phases
near mid-eclipse, leaving only part of the more extended reprocessing region(s)
to produce the weak oscillations that persist even at conjunction.
The highly sinusoidal oscillation pulse shape does not permit the
identification of the compact component in this model with emission produced by
a rotating disturbance in the inner disk or in an equatorial boundary layer,
and a standard intermediate polar model can also be ruled out. A model invoking
magnetically controlled accretion onto differentially rotating WD surface
layers may be viable, but needs more theoretical work.Comment: 28 pages, including 9 figures; to appear in the ApJ (Vol. 499
Early Evidence of Cardiotoxicity and Tumor Response in Patients with Sarcomas after High Cumulative Dose Doxorubicin Given as a Continuous Infusion
Primer registro de Macrovalsaria megalospora (Dothideomycetes-Ascomycota) en Colombia
Antecedentes y Objetivos: Macrovalsaria es un género monotípico de Dothideomycetes, ampliamente citado de regiones tropicales y secas en África, Asia y Australia. En América solo se ha descrito de Guayana Francesa y México, por lo que en el presente estudio se tiene por objetivo reportar a Macrovalsaria megalospora por primera vez para Colombia.
Métodos: Los ejemplares se recolectaron en la región Caribe de Colombia; al mismo tiempo se registraron los hospederos en los cuales crecían, se describieron y determinaron de acuerdo con las técnicas tradicionales en micología. Adicionalmente, las esporas se observaron en el microscopio electrónico de barrido. El material está depositado en los herbarios ENCB y HEUS, de la Escuela Nacional de Ciencias Biológicas del Instituto Politécnico Nacional en México y de la Universidad de Sucre, Colombia, respectivamente.
Resultados clave: Se presenta la descripción de Macrovalsaria megalospora de Colombia, una especie que se caracteriza por formar pseudotecios errumpentes, gregarios en árboles recíen muertos de Ficus americana y Terminalia amazonia.
Conclusiones: Esta especie se distribuye ampliamente en diversas zonas de la región Paleotropical y recientemente se ha descubierto en la Neotropical; no obstante, es necesario realizar una revisión filogenética de los especímenes determinados como Macrovalsaria megalospora de todas las áreas tropicales del mundo, y corroborar tanto que se trata de un género monotípico, como la importancia que tiene como fitopatógena.Background and Aims: Macrovalsaria is a monotypic genus of Dothideomycetes, widely cited from tropical and dry regions in Africa, Asia and Australia. In America it has only been described from French Guiana and Mexico; therefore, this study aims to describe Macrovalsaria megalospora for the first time from Colombia.
Methods: The specimens were collected in the Caribbean region of Colombia; simultaneously, the hosts on which they grew were registered, and they were described and identified according to the traditional techniques in mycology. In addition, the spores were observed with the scanning electron microscope. The material is deposited in the fungus collection of the ENCB and HEUS herbaria, of the Escuela Nacional de Ciencias Biológicas of the Instituto Politécnico Nacional in Mexico and of the Universidad de Sucre in Colombia, respectively.
Key results: The description of Macrovalsaria megalospora from Colombia is presented, a species that is characterized by the formation of erumpent pseudothecia, gregarious on dead trees of Ficus americana and Terminalia amazonia.
Conclusions: This species is widely distributed in various zones of the Paleotropical region and recently it has been discovered in the Neotropics. However, it is necessary to conduct a phylogenetic revision of the specimens identified as Macrovalsaria megalospora of all tropical regions of the world and confirm that it is a monotypic genus, as well as its importance as a phytopathogen
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